abstracts of papers presented at the 1962 meetings - Genetics

ABSTRACTS OF PAPERS PRESENTED AT THE 1962
MEETINGS OF THE GENETICS SOCIETY OF AMERICA
CORVALLIS, OREGON, AUGUST 29 TO AUGUST 31, 1962
ADAMS, J. T., J. A. WEIR, and P. A. KITOS, University of Kansas, Lawrence, Kansas: Glucose
metabolism in PHH and PHL strains of Mus musculus.-Oxidation of glucose to CO, by male
PHH and PHL mice was measured continuously by use of a Roth metabolism chamber and flow
ion-chamber electrometer. Each mouse was injected by heart puncture with glucose 1-, 2-, 6-,
U-Cl4, or lactate 1-Cl4, at one, five, or nine hours after onset of the controlled light period.
-From earlier 24 hour gravimetric tests, both strains produced 5.8 ? 0.12 mg of CO,/gram/
animal/hour.-Maximum C140, production occurred ten to 40 minutes following injection.
Approximately U) percent of the CO, from glucose was derived from C-2 and 12 percent from
each of C-l and C-6. Urinary radioactivity was negligible. The glucose l-C14:glucose 6-C14 ratio
approximates unity in both strains, suggesting that glucose is oxidized as a symmetrical molecule.
Essentially all combusted blood glucose can be accounted for by glycolysis and subsequent TCA
cycle activity. Considering only data obtained from mice injected at the midday period, PHL
males seem better equipped to oxidize glucose to CO,. However, study of strain-time of daysubstrate
interactions suggest that mice differ in their peaks of metabolic activity and that strain
comparisons have meaning only when measured at several different times in a 24 hour period.
(Work supported by U. S. Public Health Service Research Grant RG-7786 and Research Training
Grant 2G-246.)
AHLOOWALIA, B. S., Laboratory of Genetics, Agricultural University, Wageningen, Netherlands:
Nonpreferential pairing of translocated chromosomes in tetraploid rye.-The diploid
translocation heterozygotes of Secale cereale L. obtained by crossing cytologically normal summer
( ? ) x winter homozygous for a large-sized reciprocal translocation had summer growth
habit. The colchicine induced tetrapliods of these heterozygotes showed a strong tendency for nonpreferential
pairing of translocated chromosomes. Whereas the normal chromosomes associated
in bivalents, trivalents and quadrivalents, the translocation complex formed multivalents up to
octavalent, present as rings and chains at metaphase I. All the latter multivalent associations
were characterized by their heteromorphic nature. The degree of nonpreferential pairing as indicated
by the percentage of the chromosomes involved in multivalents was far higher for the
interchanged chromosomes (72%) than that for the normal (38%). Abnormal chromosome
segregation leading to hypoploid and hyperploid diads and tetrads, univalent laggards which
divided precociously, and bridges were observed at anaphase I and 11. A high percentage of the
microspores showed univalents and micronuclei in their cytoplasm.-In view of the hypotheses by
other authors that the S. cereale genome originated through stabilization of translocated chromosomes,
it is conceivable that such a raw genome would survive better at a diploid than a polyploid
level. One reason for the absence of polyploidy in the genus Secale as against its widespread
occurrence in the related grass genera may thus be accounted on the basis of nonpreferential
pairing of the translocated chromosomes.
AKEY, ALICE, and HELEN GAY, Department of Biology, Adelphi College, Garden City, N.Y.,
and Department of Genetics, Carnegie Institution of Washington, Cold Spring Harbor, N.Y.:
Ribonucleic acid in heterochromatin.-Cytologically well-defined heterochromatic regions, such
as the “prochromosomes” of the interphase nucleus of the spring-flowering Scilla sibirica, were
analyzed cytochemically for RNA content by enzymatic hydrolysis, and by autoradiography
following incorporation of tritiated RNA precursors. Results of hydrolysis of fixed cells with
ribonuclease alone, deoxyribonuclease alone, or consecutive treatments with both nucleases, fol-
lowed by staining with methyl green-pyronin or azure B, show that RNA is present in hetero-
chromatin. The results also suggzst that there may be two RNA components in the hetero-
chromatic regions: one that is labile and more easily digested; and a second, more resistant, which
may be complexed with DNA since it requires pretreatment with deoxyribonuclease to render

938 ABSTRACTS
it easily hydrolyzable by ribonuclease.-Autoradiography of Scilla root-tip cells into which RNA
precursors (H3-cytidine or H3-uridine) had been incorporated confirmed the presence of RNA
in the heterochromatic “prochromosomes.” After digestion of the fixed tissue with deoxyribonu-
clease, the autoradiographs showed a heavy concentration of silver grains over the “prochromo-
somes.” This radioactivity was eliminated by ribonuclease treatment. It appears that, in Scilla,
H3-cytidine is initially incorporated into RNA exclusively for a very long period of time, since
the label first appears in DNA after eight or ten hours. The possibility is discussed that the length
of this period reflects the state of the nucleotide pool and is dependent on the presence of many
heterochromatic bodies. (Supported in part by a National Science Foundation Cooperative Grad-
uate Fellowship and by USPHS research grant RG-149.)
ALLEN, SALLY LYMAN, and MARGARET SEGUR MISCH, University of Michigan, Ann Arbor,
Mich.: Genetic and epigenetic factors affecting the acid phosphatases of Tetrahymena.-Among
the family of acid phosphatases separated electrophoretically in starch gels, alternative forms of
one of these enzymes occur within inbred strains of variety 1 of Tetrahymena pyriformis. A
single zone (P-1A) appears in strains A, AI, B1, D and DI; a group of two to three zones with
more basic charge (P-1B) appears in strains B, C, E and F. Within a strain, each type breeds
true. The hybrid (P-1AB) possesses a hybrid as well as parental enzymes. Genetic analysis indicates
that these phosphatases are controlled by alleles at a single locus. A cross of A x B resulted
in 18 P-IAB pairs. When intercrossed, the hybrids gave rise to 11 A, 19 AB and ten B pairs;
backcrossed to A, to ten A and ten AB pairs; backcrossed to B, to eight B and 12 AB pairs. The
progeny of all crosses were screened immediately following conjugation. At this time the enzymatic
patterns of heterozygotes from all crosses were similar, if not identical. However, the
patterns of F1 P-1AB caryonides at 150 fissions showed marked variation. Variations now occurred
at five electrophoretic positions. Subclonal analyses of selected caryonides showed a strong
hereditary influence within a clone in pattern. Some caryonides were P-1A or P-lB, the frequency
(14%) being lower than that (58%) of caryonides with parental H serotypes. The higher frequency
is expected as a consequence of subnuclear differentiation and random segregation of
subnuclei. The lower frequency, if repeatable, might arise if other genetic factors interacted
with the P-l alleles to stabilize the hybrid condition of the subnuclei. (Supported by grant
C-3545 from the National Cancer Institute, USPHS.)
ALTENBURG, EDGAR, and LUOLIN S. BROWNING, Texas Medical Center, Inc., Houston, Texas:
Evidence for the duplicational origin of reverse mutations at the forked locus in Drosophila.
-Among approximately 490,000 offspring of f3”+ females (nonforked) derived by reverse mutation
from f3w (a forked allele) in Drosophila, 30 spontaneous mutations occurred back to forked
(of varied phenotypes), or about one forked mutation in 16,300 chromosomes. This relatively
high mutation rate of the reverted allele (i.e., of f3H+ to f 3 9 is comparable to that of f3N to f38+
in diploid material as found by us (38 in approximately 400,000, or about one in 10,600) and
previously reported by G. LEFEVRE and M. GREEN. There is also a high rate of mosaicism among
f3y+ flies; 34 forked mosaics were found among the above 490,000 offspring, or about one mosaic
in 14,400. These observations suggest that the above mutations might be duplications and deleletions
within the forked locus. The reverse mutations (of fjv to f”+) would result from duplication
of the right subsegment of the forked locus. The duplication will be a suppressor of f3N,
which is located in the left subsegment. It would occur at early prophase in a mitotic division
(of a gonia1 cell in the case of the germ track) and would result from one split X receiving both
right segments of the forked locus, and the other neither. Mutations of f3p+ to f”” would result
from deletion of one or both elements of the duplicated right segment. In the case of the mosaics,
deletion would have occurred in a somatic cell during development. The suppressor of forked
(f+ih) which arose at the same time as a forked deletion (f”), as earlier reported by MULLER
and OSTER could also be interpreted as a duplication of the right segment of the forked locus.
(Research supported by Grant RG-8889 from the Division of General Medical Sciences, U. S.
Public Health Service.)

ABSTRACTS 939
ARAKAKI, DAVID T., (Introduced by JIMMIE B. SMITH), Genetics Department, University of
Hawaii, Honolulu 14, Hawaii: Chromosomal analysis of normal and mongoloid individuals of
uarious ethnic groups in Hawmi.-The chromosomal patterns of 32 normal persons were examined
by the leukocyte culture technique. Normal samples represented seven different ethnic
groups: Japanese, Chinese, Caucasian, Hawaiian, Korean, Filipino, and Negro. The modal number
of 46 was found to characterize the chromosomal complements of these seven ethnic groups,
of which, the Korean, Hawaiian, and Filipino groups represented original chromosomal analyses.
In addition, normal karyograms from the first four ethnic groups indicated that no significant
morphological difference existed among them.-Chromosomal patterns of 13 mongoloid idiots
were examined by the same technique. The modal number for each of these patients was 47, presumably
of the trisomic-21 type. Analyses of the chromosomal pattern in several Caucasian,
Japanese, and Hawaiian patients clearly indicated a chromosome number of 47 with trisomy for
chromosome 21.
BACON, D. F., Institute of Microbiology, Rutgers, The State University, New Brunswick,
N. J.: Sexual transfer of the Hfr property from the K-12 strain to the W strain of Escherichia
coli.-Matings of F+ cultures of strain K-12 with auxotrophs of strain W yield recombinants with
very low frequency. Several Hfr cultures of K-12, however, produce recombinants with W at
high frequency; in three such cases the Hfr property was transferred to the W recipient, and
could be recovered after repeated backcrossings into W. The system studied in greatest detail involved
culture 808 (K-12, Hfr), kindly supplied by DR. F. JACOB; this culture was crossed with
a proline auxotroph (pro-) of W and pro+ recombinants were screened for their ability to transfer
leucine independence (leu+) with high frequency. The kinetics of gene transfer were studied
with the aid of a blendor and with phage T6. In the cross, K-12, Hfr 808 x K-12, leu-, the
leucine marker entered at 6.5 minutes and the maximum number of recombinants was equivalent
to 10% of the Hfr cells; in the crosses, K-12, Hfr 808 x W, leu- and W, Hfr 808 X W,
leu-, the leucine marker also entered at 6.5 minutes, but the maximum recovery of recombinants
was 1-2% of the Hfr cells; in the cross W, Hfr 808 x K-12, leu-, recombinants occurred with
low frequency (less than 0.001% of Hfr cells). (Aided by the U. S. Public Health Service and
the Office of Naval Research.)
BAILEY, D. W., Cancer Research Institute, University of California Medical Center, San
Francisco, California: Histoincompatibility associated with the X chromosome in mice.-During
an experiment on induced mutations at the histocompatibility loci, evidence was fortuitously
obtained for the existence of an unanticipated source of histoincompatibility.--Grafts were exchanged
between hybrid types in like-sexed groups by means of a tail-skin grafting technique
(BAILEY and USAMA, Transplantation Bull. 7: 424, 1960). Out of 36 grafts transplanted in
males from (BALB/c 9 x C57BL/6 8 )F1 to (C57BL/6 9 x BALB/c 8 )F1 hybrids, 31 survived
to five weeks after grafting; 14 to nine weeks. Out of 34 grafts made in the opposite direction
in males, 16 survived to five weeks after grafting; none, to nine weeks. In contrast, all 80
grafts exchanged between reciprocal hybrids in females survived to nine weeks and beyond.-
Second-set grafts on five F, males were rejected in an average of ten days, suggesting that the
phenomenon under observation was immunological in nature. In order to determine the relative
roles played by the X and Y chromosomes, nine other sensitized F, males were challenged with
grafts from both parental strains. In all cases it was the skin of the paternal strain that was rejected.
Moreover, mean survival time of these paternal-strain grafts was similar to that of
second-set grafts. It is therefore concluded that the X chromosome is the bearer of one or more
histocompatibility determining factors. (Supported by U. S. Atomic Energy Commission, contract
AT(l1-1)-34, Proj. No. 41.)
BAKER, L. H., and N. J. BECK, Hy-Line Poultry Farms, Johnston, Iowa: Genetic sampling
uariation in tester female populations of poultry.-While a recurrent to tester selection program

940 ABSTRACTS
is popular in both corn and poultry breeding research, questions regarding bases for selection of
testers and the importance of sampling variation within tester populations are unanswered.-In
an attempt to answer these questions two groups of males from a relatively heterozygous popu-
lation of chickens were individually tested by mating each male of one group to two pens of
hens from a tested population of narrow genetic origin and each male of the other group to two
pens of hens from a tester population of broad genetic origin. Daily trapnesting permitted
division of the pullet cross progeny of dams within each pen into two replicates. Thus, four
cross progeny groups were produced for each male and each group was placed at the same three
test locations at two testing times (early and late). Performance data studied were hen day egg
production, livability, and egg size.-Extensive analyses showed the following interactions to be
significant for egg size: tester female x test time, tester female x location, location x males
within tester females, and test time x males within tester females. For egg production the fol-
lowing interactions were significant: location x males within tester females and test time x
pens within males within tester females. No significant interactions were demonstrated for
livability but the variation in livability between replicates was highly significant.-This study
demonstrates the need for careful selection of female testers and for adequate sampling of the
testers in a recurrent selection program.
BAKER, L. N., and E. ANDRESEN, Antigenic Laboratory, Animal Science Department, Iowa
State University, Ames, Iowa: The B blood groups in swine.-The B blood group system in
swine was discovered as a result of investigating the antiserum of a sow which had given birth
to pigs affected with hemolytic disease (ANDRESEN, Ann. N. Y. Acad. Sci. 1962). The agglutinin
anti-B, was the first isolated antibody of this system. A second agglutinin, anti-B,, was
produced by injecting blood from two Duroc sows into a Hampshire sow. The antiserum gave
the reactions expected of an antibody antithetical to anti-B,. The observed distribution of phenotypes
among 586 offspring from 65 Duroc matings and 702 offspring from 83 Hampshire matings
supports the theory that B, and B, are a pair of contrasting characters in a closed system
within these two breeds. Thus, the theory implies that the three known phenotypes B,, B,B,, and
B, correspond to the genotypes BaBa, BaBb, and BbBb. Five of the six possible mating types have
been encountered; the missing combination is B,, x Bb which is expected to have the lowest frequency.
Segregation results from several double backcross matings for each blood group system
studied have confirmed that the B antigens are not determined by alleles in any of the nine
previously well-established systems: A, E, F, G, H, I, J, K, or L. Likewise, segregation results
have indicated that the B alleles are not sex-linked. The gene frequencies estimated from the
above data are: Durocs, q,a = 0.66, qrrb = 0.34, SE = 0.04; Hampshires, qna = 0.93, qnb =
0.07, SE = 0.02. (This work received assistance from Contract AT [Il-I] 707 from the U. S.
Atomic Energy Commission.)
BALBINDER, ELIAS, University of California, San Diego, La Jolla, California: Tryptophan synlhetase
of Salmonella typhimurium and Serratia marcexens.- As indicated by the results of
earlier genetic experiments, the enzyme trytophan synthetase of Salmonella typhimurium’ has
been found to consist of two dissociable components, A and B, separable by chromatography on
DEAE cellulose. YANOFSKY and CRAWFORD had demonstrated the existence of two oomponents
for the tryptophan synthetase of E. coli. Serratia marcescens also appears to have a two compe
nent enzyme. A Serratia mutant which, on the basis of nutritional requirements and accumulation
products would presumably lack component B activity but possess normal component A
activity, can be shown to complement “in uitro” with mutants of E. coli and Salmonella which
lack component A activity but have normal component B. Mutants of E. coli and Salmonella also
show cross-complementation in “in uitro” tests. Immunological neutralization tests indicate that
the A components of each organism are structurally different. Differences in the extent of crosscomplementation
are also apparent.

ABSTRACTS 941
BAND, H. T., and P. T. IVES, University of British Columbia, Vancouver, Canada and Amherst
College, Amherst, Mass.: Correlation between heterozygote and homozygote viabilities and the
nature of the genetic load in a natural population of Drosophila me1anogaster.-Natura1 populations
of Drosophila species studied carry genetic loads consisting of lethal to mildly deleterious
recessive genetic variants, which are usually concealed within the population in a heterozygous
condition. To distinguish between primarily mutational versus largely balanced genetic loads
KRIMBAS (1959) used the correlation between the viabilities conferred by chromosomes in homozygous
and heterozygous condition. If the genetic load is chiefly mutational a positive correlation
is expected between the viabilities of heterozygotes and those homozygous for the respective
chromosomes; if the genetic load is primarily a balanced one, no correlation is expected or even a
negative one. In an investigation of the genetic load in second chromosomes from the S. Amherst
population of D. melanogaster, similar studies have been made. For the 136 comparisons from
the September 1960 sample a correlation of - 0.08 e 0.09 is observed between random heterozygote
viabilities and those of their corresponding homozygotes. For the 152 comparisons from
the September 1961 sample a correlation of 0.12 2 0.08 is observed. Neither correlation is significant,
nor do they differ significantly from one another; changes, however. may reflect other
differences observed between the two collections. These findings suggest that the genetic load
maintained in this population is largely balanced. The continuing dynamic relationship between
environment and the drastic (lethal f semilethal) component of the genetic load observed in
this population also supports this conclusion. (Supported by National Science Foundation Grant
G-14158 and National Research Council of Canada Grant A940.)
BARNETT, W. EDGAR, and F. J. DE SERRES, Biology Division, Oak Ridge National Laboratory,
Oak Ridge, Tenn.: Evidence for nitrous acid-induced nontransition mutation.-A number of
nitrous acid (NA) and ethyl methanesulfonate (EMS)-induced ad-3 mutants of Neurospora
crassa have been analyzed for reverse mutation induction by both NA and EMS. The NAinduced
mutants may be placed into three groups: (1) those highly revertible by both NA and
EMS (- 50 percent of the NA mutants tested), (2) those revertible only by NA (- U) percent),
and (3) those which either fail to respond or respond very weakly to NA and/or EMS (- 30
percent). No mutants were found which responded only to EMS. The results are consistent with
the concept that NA may induce both types of transition (base substitutions of the purine for
purine, pyrimidine for pyrimidine type) mutation and that EMS primarily induces only one
type of transition change. It appears that NA also induces mutational changes of a nontransition
type since about 30 percent of the NA mutants fail to revert in response to either NA or EMS.
It is possible, however, that failure to respond reflects an influence of neighboring nucleotides on
reactivity of a mutant base with these chemical mutagens. Several of the revertants have been
extensively analyzed genetically to determine whether they represent true reverse mutation
or suppressor mutation. The revertants were crossed with standard wild type and 4 x 105 to
2 X lo6 progeny scored. In no case was there evidence for suppressor mutations.
BARRATT, RAYMOND W., Dartmouth College, Hanover, N. H.: Altered proteins produced by
mutation at the amination (am) locus in Neurospora.-Mutants at the am locus in Neurospora
crassa lack a TPN specific glutamic acid dehydrogenase (GAD) capable of catalyzing the amination
of alpha ketoglutarate to glutamic acid. Antisera prepared against purified wild-type
GAD strain 74A shows the presence of neutralizing cross-reacting proteins (CRM) in am,,
am, and amg . armh, am5, am6, am7, amB, amg, and amll produce no cross-reacting material. am,,
am,, amg also complement in heterocaryons as shown by FINCHAM. GAD and CRM from wildtype
74A, am,, and partial reversions ampa and amJa were isolated and purified. Each of the
four proteins migrated as a single band electrophoretically, and all four had the same mobility.
Tryptic digests and tryptic plus chymotryptic digests of the four proteins were compared by the
fingerprint technique. Partial reversion amga was found to have a peptide absent when compared
with digests of the other three strains. No additional or displaced peptide was detected on

942 ABSTRACTS
the amSa fingerprints. Amino acid analyses of HC1 and performic acid hydrolyzates of these
proteins support the above data.
BARRY, E. G., Yale University, New Haven, Connecticut: Genetic and cytologic correlations
of some Neurospora crmsa chromosome rearrangements.-Three reciprocal translocation strains
have been examined genetically and cytologically. Interchange breakpoints for T (4637)
(albino-I phenotype) have been mapped in linkage groups I and I1 and in chromosomes 1 and
6. These results for T(4f337) are in agreement with the findings of previous investigators. The
second translocation strain T (1 7084) (thiamine-I phenotype) has breakpoints in linkage groups
I and VII. No involvement of linkage group I1 has been found. The third translocation strain
T (S1007) also has breakpoints mapped in linkage groups I and VII. These genetic data for
T(17084) and T(S1007) are also in agreement with the breakpoints mapped by other investigators.
Cytological examination of meiotic pachytene, diakinesis, and metaphase I figures from
crosses of T (17084) and T(S1007) by wild type indicate that five chromosomes are apparently
free of rearrangement involvement in each strain. These free chromosomes have been identified
as 2, 3, 4, 5, and probably 6. A perfectly clear example of interchange pairing between two
identifiable chromosomes has not yet been found, but the evidence from several pachytene and
metaphase I figures favors the conclusion that there is an involvement of chromosomes 1 and 7
in both translocations 17084 and S1007.-The fact that these three translocation strains have
only one rearranged linkage group (I) and chromosome (1) in common would specify the
following correlation of linkage groups and chromosomes: I = 1, I1 = 6, VI1 = 7. These correlations
differ from those previously proposed by ST. LAWRENCE (Ph.D. thesis, Columbia University,
1952) by reversing the association of I = 6, and I1 = 1 that she has described. (Supported
in part by Public Health Service research grant E1462 to DR. DAVID D. PERKINS, Stanford
University.)
BEATTY, A. V., and J. W. BEATTY, Emory University, Atlanta, Georgia: Chromosomal aberra:ion
gradient in sectioned anther material.-Inflorescences of Tradescantia paludosa were X-
irradiated for one minte at 400r/minute in atmospheres of helium, 100% oxygen, 5% oxygen
with 95% helium or with 95% CO and 20% oxygen with 80% helium or with 80% CO, fixed
96 hours later in Craf fixative, sectioned and strained in crystal violet. After the sections were
projected and traced, cells in metaphase of the first microspore division were identified, their
position in the cross section of the anther marked, examined subsequently under oil immersion for
chromosomal aberrations of the ring and dicentric type and recorded as aberrations occurring in
the outer or inner region of the tissue. Material irradiated in atmospheres of 5% and 20%
oxygen with helium as the accompanying gas had a much higher aberration yield in the outer
layer of tissue than in the central area. Material irradiated in the other gases or combination of
gases did not show such an aberration gradient.
BECK, SIDNEY L., The University ad Michigan, Ann Arbor, Michigan: Teratogenic demonstration
of subline differences among C57 Black mice.-Pregnant female mice, representing crosses
between the HL-ZRDCT-An anophthalmic line (BECK 1961, Am. Zool. 1:436) and C57BL subline
six or ten were stressed with injections of 0.25 cc of a 0.3% solution of Trypan Blue in 0.9%
saline during the seventh, eighth, and ninth days of gestation. Pure line C57BL females were
treated in the same way, and a small group of C57BL/6 x HL-ZRDCT-An and C57BL/10 x
HL-ZRDCT-An were stressed with 0.20 cc per injection.-These and other experimental crosses
were originally designed as an elaboration and repetition of the experiments of BARBER (Am. J.
Ophthalmol. 4494, 1957).-The two sublines of the same inbred strain, when crossed with HL-
ZRDCT-An, responded very differently to the stress both from the standpoint of mortality of
fetuses (P < ,0005) and the frequency of abnormal young (P < .W2) produced. Most of the
abnormalities were eye defects. In both cases the C57BL/6 were more susceptible. The C57BL/10
pure line crosses were more subject to mortality (P < .03) but not eye defects (P > .50) than

ABSTRACTS 943
were the C57BL/6 pure line crosses. In each case the pure line crosses were more prone to fetal
death than were the outcrosses; the C57BL/10 showed more heterosis in crosses than did the
C57BL/G.-Decreasing the quantity of the tetratogen eliminated the differences between the
sublines both with respect to mortality (P > .50) and abnormalities (P > .50). (Supported in
part by USPHS Post-doctoral Research Fellowship BE-10,004.)
BECKER, W. A., Washington State University, Pullman, Wash.: Heritability of a response to
an environmental change.-The relationship of a population in two environments was investi-
gated by weighing young chickens. Progeny of 40 sires and 600 dams were randomly allotted
at hatching to two diets. Males were weighed at four weeks of age while females were weighed
when eight weeks old. Means, heritabilities and variances among individuals within dams for
males on inferior diet were: 236 grams; htq 0.21 f 0.44; h; 0.05 f 0.20 and variance 1,339. Re-
sults on superior diet were: 283 grams; hi 0.29 f 0.63; h; 0.83 f 0.22; variance 875. Genetic
correlation between diets was 0.70 and heritability of the response measured as the difference
between means of progeny on the two diets within a dam family was hi 0.21. Results of females
on inferior diet were: 585 grams; h: 0.41 2 0.68; h: 0.76 f 0.25; variance 4,387. On superior
diet: 680 grams; hi 0.66 f 0.93; hi 0.63 f 0.23; variance 3,486. Genetic correlation between
environments was 0.81 and heritability of response was hs 0.25. Use of logarithmic transforma-
tion did not significantly alter the results.
Results obtained indicated that selecting a strain for a large response to an environmental
change is feasible. Thus, strains of laboratory animals sensitive to specific treatments could be
selected by measuring the response. Also, strains of animals could be selected for resistance to
environmental stresses.
BERG, CLAIRE M., and E. D. GARBER, IJniversity of Chicago, Chicago, Ill.: Color mutants in
Aspergillus fumigatus-Prototrophic-color and auxotrophic-color mutants were obtained by
ultraviolet irradiation of the uninucleate spores of the imperfect species Aspergillus fumigatus.
The former mutants presumably represent mutations involving direct precursors of the parental
dark green color and the latter, mutations resulting in a nutritional deficiency and coincidentally,
an alteration of the parental color. An accumulation of metabolites above normal levels in the
auxotrophic-color mutants may have inhibited pigment biosynthesis by a secondary block. One
group of color mutants was autonomous and the second group was nonautonomous, yielding
green spores at frontiers or in heterocaryons. Two different mechanisms for nonautonomy have
been proposed. Three of the four diploid strains which were studied had green spores and the
fourth, buff spores. Recombinant spores were obtained from diploid colonies grown on complex
medium and, with a higher frequency, from diploid colonies grown on this medium containing
DL-para-fluorophenylalanine. (Supported by funds from the U. S. Public Health Service and
the Abbott Memorial Fund, University of Chicago.)
BIANCHI, A., M. BUIATTI,
Institute of Genetics, University of Milan,
Italy: Recombination frequency in presence of B chromosomes in maize.-Plants heterozygous
for markers of chromosome 9 and differing for presence of B chromosomes us. their absence have
been selfed and/or backcrossed to and by a multiple tester stock homozygous for the appropriate
recessives. The frequencies of crossover in F, possessing no B chromosome were as follows in
the indicated regions: YgSh: 23.09 f 0.38; Sh-Wz: 20.78 f 0.37. When B chromosomes are
present (in numbers of 4-6 mainly, according to personal communication of DR. RANDOLPH
who provided this material) the corresponding values are: YgSh: 22.64 2 0.83; Sh-Wz: 20.04
f 0.75 (The standard error has been calculated making use of ALLARD'S formulas, since F, and
backcross data have been pooled.) The coincidence value is for the former case 0.19, while in the
latter one it turns out to be 0.30.-The data do not indicate that the presence of B chromosomes
and C. VAN DE WALLE,

944 ABSTRACTS
results in significant variation of recombination frequency in the tested regions, although further
experiments are needed to eliminate a possible influence of the genetic background which was
slightly different in the two F, differing as to the B-chromosomes presence-absence. (It is, however,
difficult to obtain really comparable genetic backgrounds when the two perspective stocks
have to differ as to B-chromosome endowment.) On the other hand, B chromosomes may play a
role in affecting A-chromosome mechanics, as has been already reported for their nondisjunction
(BIANCIII et al., Z. Vererb. 92:213, 1961) as well as for chromosomal interference as suggested
by HANSON (Maize Genetics Coop. News Letter 35: 61-62, 1961) with data similar to those
above mentioned.
BODMER, WALTF.R F., Department of Genetics, Stanford University School of Medicine, Palo
Alto, California: Znactiuation of linkage in Bacillus subtilis by deoxyribonucleases.-The DNA
isolated from a prototrophic B. subtilis was incubated with various endonucleases (enzymes
which attack DNA molecules at internal phosphodiester bonds). Samples withdrawn at different
times were added to an appropriate inhibitor of the relevant enzyme. Samples treated
for varying times were assayed for transforming activity on a strain which carries four linked
auxotrophic markers. The activity of the DNases was also followed by measuring the drop in
viscosity of the DNA. The rate of inactivation of transforming activity is generally higher than
the rate of loss of viscosity, the ratio between these rates depending on the enzyme used. In all
cases the quadruplet transfer, (designated 11 11 ) which encompasses all four markers from the
DNA, was the most rapidly inactivated. The rates of inactivation of singlet, doublet and triplet
transformants increased progressively. Following very mild enzyme treatment the drop in 11 11
transformants is partially compensated by a rise of the 01 IO genotype, which occurs only infrequently
when using untreated DNA. The inactivation curve for doublet and singlet genotypes
shows either an initial lag followed by an exponential decay or an initial exponential decay
followed by a shoulder, depending on the treatment conditions. The kinetics of inactivation are
complicated by the fact that breakdown products formed from the original molecule may give
rise to certain genotypes more frequently than did the original molecule, but almost certainly
have a lower transforming efficiency.
BRAYMER, H. D., and D. 0. WOODWARD, Bionucleonics Department, School of Aerospace Medicine,
Brooks AFB, Texas: Density gradient studies with adenylosuccinase from interalleh
heterocaryons in Neurospora.-Utilizing a sucrose density gradient (MARTIN and ARIES, J. Biol.
Chem. 236: 1372, 1960) adenylosuccinase sedimentation rates were measured in a swinging
bucket rotor in a model L Spinco ultracentrifuge. Adenylosuccinase was extracted from several
different interallelic heterocaryons and studied under varied conditions. Catalase and alcohol
dehydrogenase were used as standards. Based on these standards, approximate molecular weights
have been calculated for the different adenylosuccinase preparations. Adenylosuccinase from
wild-type Neurospora has a molecular weight of approximately 190,000. Most of the heterocaryon
adenylosuccinase extracts had the same sedimentation rate as wild-type adenylosuccinase.
Others, under certain conditions had sedimentation rates roughly corresponding to molecular
weights which are multiples of 190,000 (or multiples of 95,000). In some preparations more
than one form of adenylosuccinase was present thereby giving more than one sedimentation
peak. In all of the sedimentation studies with adenylosuccinase including the wild-type enzyme,
a significant amount of adenylosuccinase activity is lost during centrifugation (usually 50 percent
or more). The heterocaryon enzymes are less stable than the wild-type enzyme during
centrifugation; however, there is considerable variation depending on which pair of mutants is
used in the heterocaryon.-These results suggest that aggregation of some type is possible and
does occur under certain oonditions. However, in the majority of the interallelic heterocaryons
between ad-4 mutants aggregation involving adenylosuccinase has not been detected. Variation
in sedimentation rate has not been found for any wild-type adenylosuccinase preparation.

ABSTRACTS 945
BROWN, RUSSELL V., and A. W. NORDSKCG, Iowa State University, Ames, Iowa: Correlated
responses in blood group gene frequencies with selection for body weight and egg weight in
the fowl.-Four generations of selection have been completed in four single trait lines of White
Leghorns. These are, respectively, B and C (large and small body), and D and E (large and
small egg). Adult body weights average 6.1, 3.2, 4.7 and 3.7 pounds, respectively, for B, C, D,
and E. Corresponding average egg weights are 66, 53, 67 and 50g. These results demonstrate a
strong correlated response in egg weight when selection is for body weight.-Blood group
studies have been completed on breeders selected to produce the sixth generation. Test reagents
developed from isoimmunization and heteroimmunization (rabbits) have differentiated at least
28 B alleles, five E alleles, and two each of D, X and 2 alleles. Line differences in gene frequency
estimates based on reactions to 11 test reagents are greater than random drift expectation.
Also, the gene frequency arrays from the same 11 test reagents are strongly correlated for
lines B with D and C with E but otherwise not. This s’iggests that blood group gene frequency
equilibria have changed as a correlated response to selection for body weght and egg weight.
(This work was supported in part by Grant No. G-8887 of the National Science Foundation.)
BROWNING, LUOLIN S., and EDGAR ALTENBURG, Texas Medical Center, Inc., Houston, Texas:
Thc relatively high rate of mosaicism among the mutations induced in the X chromosome of
Drorophila by monofunctional quinacrine mustard.-Mosaics comprise a very high proportion
of the mutations induced by monofunctional aukacrin- mustard in the X chromosome of
Drosophila, as follows. Among approximately 58,000 F, females derived from P, males intraabdominally
injected with the quinacrine mustard and examined for visible mutations at 13
selected loci in the X chromosome by Muller’s Maxy technique, 60 visibles were detected, and
all but five of these (or 92%) were mosaics (making 1 mosaic in approximately 1,050 F,
females us. 1 wholebody in 11,600). The proportion of mosaics among the lethal mutations was
correspondingly high; namely, 16% lethal mosaics (five among 30 F, females tested for gonadal
lethal mosaicism) versus 3.8% wholebody lethals (115 in 3.037 F, females). In the case of the
visible mosaics, the mutant tissue sometimes comprised only a relatively small part of the body
(such as a part of one eye), an event indicative of a rather long-delayed effect of the agent.
The great majority of the visible mosaics (51 of the 55 above mentioned) were not transmitted,
from which fact it follows that the mutant areas often were not extensive enough to include
the gonads. The visibles were fairly well distributed among the 13 loci under study (the loci of
the nontransmissible were judged by their mutant phenotypes). The high rate of mosaicism in
the present experiments is comparable to that induced at the dumpy locus, as reported by
CARLSON and OSTER, but the total mutation rate recovered at all 13 of the Maxy visible loci is
less than that at the dumpy locus alone. (Research supported by Grant C-5961 from the NationaI
Cancer Institute, U. S. Public Health Service.)
BURDICK,
A. B., Purdue University, Lafayette, Indiana: The recombinational array of mu-
tant elements at the m-dy locus in Drosophila me1anogaster.-Five recombinationally separable
mutant elements are known for the m-dy locus. The order of these elements is an unequivocal
sequence, but probably not linear. One aspect of nonlinearity can be removed if we assume that
the three “inside” elements in the sequence of five are deficiencies, or losses of lO-ZO% of the
locus. Several other elements are known which behave recombinationally as if they were 4.0-
60% losses. In fact, all elements for which recombination difference calculations can be made
(i.e., all “inside” elements) are deficiencies in this sense. Another aspect of nonlinearity-the
fact that the “outside” elements do not recombine nearly so frequently (in some cases not at
all) as some of the “inside” elements-can not be removed by mutually consistent assumptions
about the deficiency size of the elements. A directionally oriented polygon or circle can be used
to express these relationships.-Nine different transheterozygous combinations of elements have
yielded one or more nonclassical recombination types-types in which the outside markers .v
and g are not recombined at the same time that the m-dy elements are. These can be accounted
for as a loss or change in directional orientation of the polygon. (Supported by NSF G-18104.)

946 ABSTRACTS
BUTLER, L., University of Toronto, Toronto, Canada: The effect on fruit size of the genes on
chromosome 2 of the tomato.-This chromosome contains genes with a pleiotropic effect on
fruit size as well as genes whose major effect is on fruit size. In these preliminary crosses an
attempt is made to partition the fruit size differences attributable to each of these causes. From
a physiological viewpoint it was expected that any pleiotropic effects of the genes suf, dil, and
s, would reduce fruit size, but only s shows such a reduction. The gene p increases fruit weight
by five percent and d decreases it by five percent. Pear shape (0) has a major influence since
it decreases fruit weight by 30%. It is suggested that the ovary of an o plant contains the same
number of cells as an ovary of an 0 plant with similar genetic background, but the cells in o
are arranged with a greater number on the polar axis than on the equatorial one. Since for a
given number of cells the sphere gives a maximum volume and weight, then the effect of shape
itself decreases the weight of o segregates. Locule number (Lc) also has a major influence on
fruit size but the data do not prove conclusively whether this is a gene which is closely linked
with 0, or whether it is a pleiotropic effect of 0. The data suggest that there are fruit size genes
between aw and 0, and also between s and the centromere.
CARSON, H. L., Washington University, St. Louis, MO.: Selection for parthenogenesis in
Drosophila mercatorum.-The capacity of this species to reproduce by thelytokous parthenogenesis
was measured by determining the number of unfertilized eggs capable of developing into
viable imagoes. Impaternate flies are mostly 2n 0 0; no 311’s have been recognized. Between
one and two percent sterile XO 8 8 are produced, depending on the strain. Rates (imagoes/106
unfertilized eggs) were: El Salvador 967; Rochester 38; Rochester x Salvador 21; Lima, Peru
0; Guatemala 0. Following six cycles of alternate parthenogenetic and sexual reproduction,
taking about nine months, rates are: Salvador 8000; Rochester 923; Rochester X Salvador 974.
Lines maintained without sexual reproduction showed even greater increases, the most striking
being an impaternate Salvador line (S-1-Im) isolated after one cycle of parthenogenetic and
sexual reproduction and another line, Rochester x Salvador (RS-3-Im), isolated after three
such cycles. The rates in these lines, when tested after approximately 12 generations of parthenogenetic
reproduction, were 32,776 and 33,000, respectively, that is, roughly 3.3%. This is approximately
a 34-fold increase over the highest rate in unselected strains.
CASE, MARY E., Yale University, New Haven, Conn.: Forward and reuerse mutational studies
with ethyl methanesulfonate and nitrous acid in Neurospora crassa.-Two mutagens, ethyl
methanesulfonate (EMS) and nitrous acid (NA) have been used to induce mutations by the
filtration concentration procedure at four different loci in Neurospora: ad-4 and ad-8 (adeninerequiring
mutants), hist-I (histidine-requiring) and pan-2 (pantothenic acid-requiring) . Two
criteria were then utilized to investigate the nature of the forward mutational events leading to
auxotrophy: (1) the relative reverse mutability of such mutants with EMS and NA and (2) the
level of activity for the enzyme adenylosuccinase (as compared with wild type) in revertants at
the ad-4 locus. The results of the reverse mutation tests indicate that EMS-induced and NAinduced
mutants can be classified in four different ways: (1) those that revert with neither
mutagen although they can, in general, revert spontaneously, (2) those that revert with both
EMS and NA, (3) those that revert with EMS only, and (4) those that revert with NA only.
Comparable tests were also made with ad-4 and pan-2 mutants derived from ultraviolet and
X-ray treatment. Assays for adenylosuccinase activity in EMS-induced and NA-induced revertants
indicate that the level of enzyme activity in most such revertants is not equivalent to
that in wild type. The results of these experiments suggest that in Neurospora many mutational
changes to auxotrophy induced by EMS and NA are more complex than simple single base
pair changes in DNA. (Supported in part under a contract AT (30-1)-872 with the U. S.
Atomic Energy Commission.)
CASPAR, A. L., and W. R. SINGLETON, Blandy Experimental Farm, University of Virginia,
Boyce, Virginia: Mutations induced during maize microsporogenesis.-Different stages in the

ABSTRACTS 94 7
development of corn pollen show large differences in the number and type of endosperm muta-
tions recovered. The most sensitive stage for induced loss of endosperm markers is five days
before the pollen is shed. This probably corresponds to the prophase of the second pollen mitosis.
One thousand roentgens of gamma radiation given at the rate of 46r/hr at this stage produces
twice as many losses of marker genes (120 x 10-4) as that delivered at either four or six days
before pollen shedding. This five day rate is ten times that of mature pollen (radiated 0, 1, 2, or
3 days before shedding). The genes CZ Sh Bz and Wz in chromosome 9 were studied. Most of
the losses induced involve large rearrangements of chromosomes. Only six percent of the mu-
tations involve the loss of but one gene in chromosome 9, one percent the loss of two genes,
20% the loss of three genes, and 73% the loss of all four genes being studied. The chromosomal
type losses begin increasing at about 15 days before pollination. Chromosomal losses from radi-
ation given earlier than 15 days before pollination are about twice the control rate and at five
days are about 100 times the control. Eleven mutations for single genes which showed no
evidence of sterility have been recovered from radiation given between 19 and 13 days before
mature pollen. These were most likely induced after meiosis and before the first pollen mitosis.
We have also recovered four “gene” type mutations from material radiated before meiosis. One
thousand roentgens of gamma radiation given at the rate of Mr/hr during these stages produced
shrunken “gene” type mutants at the rate of 53 x 10-6. The control rate is about 2 x 10-6.
CENTER, E. M., Stanford University School of Medicine, Stanford, California: A comparison
of some teratogenic effects in mice.-Since finding that nitrogen mustard (HN, form) is
effective as a teratogenic agent (DANFORTH and CENTER, Proc. Soc. Exptl. Biol. Med. 86:
705, 1954) other chemicals have been investigated in this regard. Beyond a few vascular
changes, it is doubtful that any definite morphological abnormalities occurred among a
limited number of embryos treated in utero with Feulgen solution. Following propyl-thiouracil
treatment of 35 pregnant females, it was also difficult except in five litters to estimate whether
any definite effects were resultant. In comparison with HN, this is seemingly a relatively ineffective
agent.-Recently, experiments were begun with nitrosoguanidine, this chemical is, like
HN,, reasonably efficient at inducing abnormalities. Perhaps this can be best indicated by comparkg
the results of these two agents. Although it should be emphasized that strain differences
in response and variations in severity of treatment may call for some qualification of comparative
statements, it seems evident that nitrosoguanidine has a more pronounced effect on the
earlier embryonic stages of seven, eight, and nine days than HN,. On the other hand, of the two,
HN, has an apparently greater effect on developing embryos on days 13, 14, and 15. While
effects resulting from both chemicals include edema, vascular changes, eye defects, abnormal
tails, and digital abnormalities, nitrosoguanidine tends to reduce in size all elements of the foot
whereas HN, tends to suppress completely the development of one or more individual digits.
CHAPIN, MARGARET,
and G. R. DUBES, University of Kansas School of Medicine, Kansas City,
Kansas: Adenine-resistant mutant of poliovirus.-In 1957 and 1961 we reported cystine-response
(CT) mutants and tryptophan-requiring (tr) mutant of poliovirus, respectively. Now we report
an adenine-resistant (ad) mutant, which was selected by 14 passages, starting with wild-type
Brooks virus, on monkey kidney tissue cultures under medium containing 3 miv adenine, a
concentration strongly inhibiting wild-type virus but not markedly cytotoxic.-Plaque produc-
tion by mutant is slightly inhibited and rate of appearance of progeny virus from it is dimin-
ished slightly by 3 miv adenine; by both these criteria wild type is strongly inhibited. Adeno-
sine (5 mix) and adenosine-5’-phosphoric acid (4 miv) similarly differentiate between mutant
and wild type, though they are less inhibitory than adenine. Neither wild type nor mutant is
inhibited by high concentrations of guanine (1 miv), cytosine (12 miv), uracil (6 mix), or
thymine (9 miv) . Surprisingly, mutant is cystine-nonrequiring, in contrast to cystine-requiring
wild type. That an adenine-resistant virus need not necessarily be cystine-nonrequiring was
shown by selection of a cystine-requiring mutant (still adenine-resistant) by eight passages,
starting with ad mutant, on 30” cultures under medium with 1 mM L-cystine and,3 mM

948 ABSTRACTS
adenine.-Progenies in 24 plaques initiated by intact ad virus and developed under medium
without adenine were adenine-resistant; of the progenies in 33 plaques initiated by infective
ribonucleic acid prepared from mutant and similarly developed, 30 were adenine-resistant and
three were genetically partially reverted in adenine-response. (Aided by a grant from the Na-
tional Foundation.)
CHORAZY, M. R., A. BENDICH, and D. J. HUTCHISON, Sloan-Kettering Division, Graduate
School of Medicine Sciences, Cornel1 University Medical College, New York, N.Y.: Zsolation of
chromosomes from mouse leukemia cells.-Physicochemical studies on the structure and function
of nucleic acids and proteins in chromosomes have been hampered by the inaccessibility of
intact chromosomes. A method has been developed for the isolation of chromosomes from ascitic
L1210 mouse leukemia cells. For isolation, cell division was arrested at metaphase by administration
of colchicine to leukemic mice on the fourth day of neoplastic growth, six or 15 hours
before cell harvest. Washed leukemic cells were suspended in 0.003 M CaC1, for seven minutes,
and one volume of 0.003 M CaC1, in 0.1 M acetate buffer, pH 5.6 was added. After five minutes,
formamide was added (10% final concentration) and the suspension shaken gently with glass
beads for two minutes. Most of the metaphase cells were ruptured dispersing their chromosomes,
without damage to nuclei of resting cells. Separation of the unbroken cells and nuclei was
achieved by underlayering the “homogenate” with 0.8 M sucrose in CaC1,-acetate buffer and
centrifugation for 5-7 minutes at 100 x g. Chromosomes were sedimented from the supernatant
by underlayering with 0.8 M sucrose and centrifugation for ten minutes at 1500 x g. The pellet
was examined microscopically and when necessary these steps were repeated. Isolation was
performed at 0-4°C. The chromosome pellet was resuspended in 0.25 M sucrose in the CaC1,acetate
buffer and stored at -18°C. The microscopic appearance of the chromosomes did not
change after three weeks of storage.-The isolated chromosomes showed the same characteristic
shapes and sizes as those obtained by cytological “squash” techniques.
CHU, ERNEST H. Y., Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.:
Photoreactiuation and action spectrum of ultrauiolet-induced mammalian chromosome aberra-
tions-A clonal embryonic cell line (CH24) from the Chinese hamster was used. More than
95% of the cells had an identical quasidiploid karyotype (22 chromosomes). Autoradiography
using H3-thymidine indicated that the average cell generation time was 24 hours (G, plus
mitosis, 12-14 hr; S, 8 hr; G,, 2 4 hr). Monochromatic ultraviolet (UV) surface exposures,
ranging from 25 to 200 ergs/“*, were administered at a uniform intensity. All metaphases
accumulated up to 24 hours after UV irradiation exhibited aberrations of the chromatid type.
Both chromatid and chromosome types appeared at 30 hours; at 42 hours, only the latter was
found. In both categories, the UV-induced aberrations were qualitatively indistinguishable
from those induced by X rays in both plant and mammalian materials. Aberration frequencies
increased with dose and seemed to follow the kinetics expected from the number of breaks
involved. The UV action spectrum for production of chromosome aberrations reached a peak
frequency at 2652A. At 2804A, although the scorable aberrations showed a slightly lower
frequency than at 2652A, there were additional chromosomal abnormalities, such as fuzziness,
extreme fragmentation and shattering. The total aberrations might well be the highest at this
wavelength.-When a posttreatment of visible light (3300-4400 A) was given to cells immedi-
ately after UV irradiation, the final appearance of aberrations was reduced by 50-70%.-These
results suggest that UV damages both DNA and perhaps protein moieties of chromosomes. Addi-
tionally, it impairs the repair mechanisms for broken chromosomes. For a certain proportion of
aberrations, DNA is probably the site of primary damage and this damage is reparable by pho-
toreactivation of enzyme(s) already present in the cell.
CLANCY,
C. W., Department of Biology, University of Oregon, Eugene, Oregon: A specific (?)
modifier of white-satsuma (,sat) in Drosophila.-A recessive factor located in the third chromo-

ABSTRACTS 949
some closely linked to scarlet (st) is under study with respect to its action on the eye pigment
phenes in the white series of “alleles.” Its action in relation to wsat is readily detected in the
compounds, wsat, U and wsat;st, but not in wsat alone. When homozygous in compounds of
wSat with the genetic blocks to ommochrome formation indicated, the modifier suppresses the
residual pteridine components normally found in the eyes of these and similar compounds with
other dark members of the white series. However, when appropriately comparable compounds
involving st were prepared with the following members of the white series: apricot (wa), blood
(wal), cherry (wch), coral (wco), colored (wcol), eosin (we), and spotted-2 white (sp2-w) no
readily visible effect was observed. Other white mutants are being tested.-Preliminary work
utilizing paper chromatographic methods of HADORN and MITCHELL (1951) and HADORN and
KUHN (1955) confirm and quantify in a different way earlier results derived by colorimetry.
In wsatu; z males, the drosopterines from the heads are almost completely suppressed, and certain
other components of the pteridine inventory are significantly reduced, especially isoxanthopterin.
(Some of this work was done at the Zoological Institute of the University of Zurich
under Special Research Fellowship No. GF 12,237, USPHS.)
COMSTOCH, R. E., and LAURENCE H. BAKER, Institute of Agriculture, University of Minnesota,
St. Paul, Minn.: Monte Carlo studies of linkage effects in population genetics.-An electronic
computor was employed to simulate the genetic and nongenetic factors involved in
reproduction, phenotype expression, and selection. The net effect of procedure was as if gene
frequencies and effects on total genotypic value and genetic variances could be determined in
full detail for a sample of loci in a natural population. Information relative to 35 “genes” was
obtained.-Variables in the study were number of parents per generation, number of offspring
per parent, linkage relations among the “genes,” degree of dominance and amount of nongenetic
variance.-It had been predicted from mathematical analysis that linkage disequilibrium
generated by finite population size could lead, in the presence of selection, to: (1) reduction in
the rate of “drift loss” of alleles, (2) seeming advantage (at the locus level) of the heterozygote
over homozygotes in the absence of overdominance, (3) decrease in additive genetic variance,
and (4) inflation of dominance variance and total genotypic variance. All of these were
demonstrated.-Studies were designed to simulate artificial selection for a single quantitative
trait. Conditions were vaned to simulate heritability over the range from 15 to 50% when
linkage was absent. Rate of “drift loss” of alleles was reduced as much as 50% by linkage
depending on the combination of variables. Heritability was sometimes reduced to near zero
at the same time that total genetic variance increased because of inflation of dominance
variance.-These results suggest that the full impact of linkage in pulation genetics may be
much greater than generally realized.
DAVIS, R. H., and VAL W. WOODWARD,
University of Michigan, Ann Arbor, Mich., and Rice
University, Houston, Tex.: Euidence for the dual function of the pyr-3 locus of Neurospora.-A
survey of 30 pyr-3 mutants of Neurospora was undertaken in regard to the activity of the en-
zyme asparate transcarbamylase (ATC), and the response of each mutant to a nonallelic sup-
pressor mutation, s. The ATC reaction yields the pyrimidine precursor, ureidosuccinic acid
from carbamyl phosphate (CAP) and aspartate. The suppressor mutation depresses the orni-
thine transcarbamylase reaction, which utilizes CAP and ornithine to yield citrulline. It was
found that 23 pyr-3 mutants displayed no activity for ATC and were unsuppressible by s; the
remaining seven mutants displayed normal ATC activity and were suppressible. Because the s
gene had its effect on one mode of CAP utilization, it is felt that its suppressor action in regard
to pyr-3 mutants containing ATC lies in compensating for a deficiency in a pyrimidine-specific
CAP. This implies that pyr-3 mutants may affect CAP synthesis as well as the ATC reaction.
Complementation among the pyr-3 mutants studied supports the view that two functions are
controlled by the pyr-3 gene. The distribution of the two types of pyr-3 mutations on the genetic
map of the locus suggests that if two reactions are involved, they are catalyzed by a single

950 ABSTRACTS
protein. (Supported by grants from the American Cancer Society, The National Science Founda-
tion, and The National Institutes of Health.)
DAWSON, PETER S., University of California, Berkeley, California: Aberrant segregation ratios
in Tribolium castaneum.-Recent studies on the mapping of a sex-linked lethal (I,) in this
species of flour beetles have led to the discovery of some aberrant segregation phenomena. The
first of these involves sex ratios. A female later shown to be of the genotype +/l, produced a
progeny of three fema1es:one male (240:84) instead of the expected 2:l. Females from this
progeny were mated to several types of males with the following results: nine, 3:l ratios;
nine, 2:l ratios and eight, 1:l ratios. Females taken from the second series of 3:l ratios have
continued to segregate for all three types, while females from the 2:l series have produced
progenies of only 2:l or 1:l.-Further indication of abnormal segregation comes from two
series of matings of +r/Z2 + 9 x +r/- 3. In both cases the females used came from 3:l
progenies. From linkage tests red (r) is known to be approximately 25 units from I,. In some
matings, 2: 1 sex ratios were obtained, but the expected segregation for red did not occur. Male
offspring had higher frequencies of wild type than expected, and female off spring had higher
frequencies of red.-A final striking result was found in two sets of matings involving the
lethal and three sex-linked genes. The females used were expected to be i/z +/12, % +/f.
In all ten matings from one set and 20 from the other, the females segregated for the lethal.
Further work is in progress on all three of these phenomena.
DEFRIES, J. C., and R. W. TOUCHBERRY, University of Illinois, Urbana, Ill.: Genetic effects
of radiation on egg production of Drosophila meZanogaster.-Although important human characteristics
and most of the productive traits of domestic plants and animals are biometrical in
nature and are probably controlled by polygenic systems, little evidence is available concerning
polygenic mutations. The present report describes one of a series of studies initiated by the
authors to assess the genetic effects of radiation on biometrical traits.-Both newly emerged
males and females from Luce’s wild-type strain were subjected to various dosages of y-irradiation
(0, 500, 1000 and 1500r) and mated in all passible combinations, resulting in a four X
four factorial arrangement of treatments. Three mating pairs were included in each subclass of
two identical experiments, requiring a total of 48 mating pairs per generation. Mean daily egg
production over a ten-day period of the treated females (generation one), their progeny (generation
two), and offspring (generation three) resulting from a full-sib mating of generation
two was obtained in both experiments. Somatic effects would be expressed in generation one,
whereas genetic effects would be expressed in generations two and three. The significance of the
linear and quadratic main effects of treatment on males and females, as well as the various
interactions, were determined by orthogonal comparisons. In general, the results support previous
evidence found by the authors (TOUCHBERRY, VERLEY and DEFRIES, Genetics 47: In Press,
1962) that radiation induced polygenic damage in surviving offspring is not large. Similar data
regarding the genetic effects of radiation on other biometrical traits of Drosophila observed in
these experiments will also be presented. (This investigation was supported in part by research
grant RG-7951 from the Public Health Service.)
DE SERRES, FREDERICK J., Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.:
Factors influencing wcombination and chromosome interference in Neurospora-Previous
studies (DE SERRES, Cold Spring Harbor Symposia Quant. Biol. 23:111, 1958) have shown that
both the map distances and the type of chromosome interference obtained in crosses of ad-3
mutants depended on whether strains were of identical or diverse origin. Since the ad-3 mutants
induced in unrelated wild-type strains were crossed into a 74A background, the variation observed
was attributed primarily to localized differences in the structure of homologous chromosomes.
To extend these findings, an experiment was designed to test the effect of systematic alteration
of the structure of homologous chromosomes between other linked but nonallelic markers.

ABSTRACTS 95 1
An approach to this problem has been made possible in Neurospora by accumulation of markers
induced both in wild-type 74A and other unrelated wild-type strains at the ragged, hist-3,
ad-3A, and nic-2 loci. Crosses involving markers at the ad-3A and nic-2 loci have shown that
a systematic increase in the homogeneity of homologous chromosomes in the ad-3A-nic-2 region
was correlated with a decrease in the frequency of recombination. In other crosses, the lowest
map distances between markers at all four loci were obtained when homologous chromosomes
were derived from the same wild-type strain and the highest map distances when homologs were
of diverse origin. Furthermore, double exchange events in the ragged-hist-3 and hist-3-ad-3A
regions showed negative interference when homologous chromosomes were derived from the
same wild-type strain and positive chromosome interference when of diverse origin. An expla-
nation of these observations in terms of the “effective pairing” concept (R. H. PRITCHARD,
Heredity 9:343, 1955) will be presented.
EBERHART, BRUCE M., P. R. MAHADEVAN, and METTIE B. WHIPPLE, Princeton University,
Princeton, N. J.: Genetic control of the P-glucosidases of Neurospora crassa.-A mutant (gluc-I)
of Neurospora has been obtained that is low in P-glucosidase activity. Three enzymes that attack
p-glucosidic linkages have been compared in gluc-i and wild-type (SY7A) strains. The gluc-1
mutation expresses itself as a reduction in aryl-P-glucosidase, while cellulase and cellobiase are
unaffected by this mutation.-Any attempt to obtain mutations affecting these other enzymes is
made difficult by the overlap in their substrate specificities. The P-glucosidases of Neurospora
have been separated by gradient elution from a DEAE cellulose column. They differ in thermostability,
substrate specificity, affinity for similar substrates, pH optima, and other properties.
Changes in growth conditions cause great changes in the ratios of P-glucosidases in wild-type
mycelia. At temperatures above 30°C cellobiase is greatly reduced. All P-glucosidases are induced
by addition of p-glucosides to the growth media.--Two screening procedures to obtain specific
mutations concerning cellobiase and cellulase have been designed. These procedures (based on the
DE SERRES method) use the optimum growth induction condition for each enzyme in order to
diminish interference by related P-glucosidases.
EDWARDS, JAMES W., and ELDON J. GARDNER, Utah State University, Logan, Utah: Genetic
analysis of a Drosophila melanogaster mutant phenotypically similar to the fourth chromosome
eyeless mutants.-TuRNm and GARDNER (Genetics 45: 915-924) reported the occurrence of flies
with a wide range of morphological abnormalities of the eyes. Because of its phenotypic resemblance
to the fourth chromosome eyeless mutants, the new stock, which was developed by inbreeding,
was designated tentatively as eyeless-prime (&). Genetic analysis has shown that the
major gene associated with the phenotype is located at 97 t 3 crossover units from the left end of
the third chromosome. The new descriptive name eyes-reduced with symbol eyr has been chosen
to replace eyeless-prime. In crosses between eyes-reduced and a wild-type stock, Cockaponsett,
64.8 percent of the F, flies exhibited an eye abnormality. To study the presumed genetic modifiers
of eyr, five homozygous lines were developed using crossover suppressors. These lines possessed
different combinations of eyes-reduced and wild-type chromosomes. By intercrossing,
significant differences were noted with respect to percent of F, flies exhibiting structural eye
abnormalities. Apparently, recessive modifier (s) were carried on the second chromosome of the
eyes-reduced stock. When this stock is homozygous, the F, or heterozygotic expression is decreased.
Preliminary data suggesting a possible interaction between eyes-reduced and ey, eyz, or
ey4 by means of an interaction of modifiers have been obtained. Experiments are being designed
to investigate the action of modifiers in these stocks. (Aided by Damon Runyon Memorial Fund,
Grant DRG-l78F, and by the American Cancer Society, Grant P22-C.)
ERK, FRANK C., and NANCY A. NEVOLE, State University of New York, Long Island Center,
Oyster Bay, N.Y.: The Occurrence of heritable melanotic tumors in Drosophila after larval feeding
OR extracts of tumorous fZies.-When saline extracts of Drosophila melanogaster adults,

952 ABSTRACTS
characterized by free-floating abdominal melanotic tumors (tu bw), were applied to a food
surface upon which eggs were laid by nontumorous, wild-type flies, some of the eggs developed
into F, adults having melanotic tumors similar in form and distribution to those of the original
tumor strain. Tumorous offspring appeared with a low initial frequency of less than three
per cent, but when bred together produced subsequent generations of flies with similar tumors.
The proportion of tumorous flies in a given generation is quite variable, and up to 70% of flies
may be tumorous after several generations of selection. In some strains the tumors appeared in
early larval stages, becoming very large before or during pupation and preventing eclosion in
numerous cases, Strains showing early and extreme tumor expression were inevitably lost be-
cause of lethality.-The proportion of tumorous flies in a culture tended to decrease from a
first-day high to zero over a period of five days, suggesting that some essential factor, possibly
an infective agent, was being either exhausted or inactivated with time. Males appear to be
more susceptible to the tumors than females, and this difference persists throughout successive
generations. The modes of infectivity and transmissibility of the tumor-causing agent remain
obscure. A tentative hypothesis is suggested that a viral agent becomes localized in the larval
gonads, and subsequently is transmitted by way of the gametes. The agent is apparently species
specific, for attempts to induce tumors in D. simulans by similar techniques were unsuccessful.
FLORY. W. S., and W. R. SINGLETON, Blandy Experimental Farm, Boyce, Virginia: Effects of
gamma radiation on woody plants.-Nursery plants of 34 kinds of woody trees and shrubs were
given a series of treatments with gamma rays (Cobalt-60) in 1958, and 23 kinds were radiated
in 1959. Dosages used in 1958, ranging up to 20.000r units, were either lethal or injurious to
the 15 coniferous taxa, but initially resulted in little apparent effect on any of the 19 angiospermous
varieties. The much lighter dosages of 400, 800, 1200 and 1600r units were used in
1959. In 1959 there were 14 nonconiferous plants in each treatment, and numbers of surviving
plants from the several dosages, after one year, were 14, 14, 12. and 12, respectively. Survivors
from each lot of 32 coniferous plants in comparable treatments were 24, 22, 18, and 4, respectively.
Thus with conifers, but not with woody angiosperms, the 1600r dosage resulted in a
high percentage of, and even the 4.00 to 1200r treatments in considerable, lethality. In Dwarf
Korean boxwood 20,000r killed the plants, while 10,000r resulted in elongated shoots. Similarly,
Arnold’s Dwarf Forsythia after 20,000r produced “giant” shoots. These longer internoded
shoots only appeared two and three years, respectively, following treatment.-Little is known
about inheritance in woody plants, and cause for the change from the dwarf condition is uncertain.
Possibilities include induction of (1) a sudden change in plants that were already
periclinal chimaeras; (2) polyploid sectors; and (3) the release of restraint on a factor inhibiting
internode growth and length.
FOLSOME,
C. E., Boston University, Boston, Mass.: Fine structure genetic analysis of recom-
binational topography in the phage T4 rll region.-Twenty-three sequentially arranged areas
of the rII region bounded by 27 rII mutants have been located relative to four UV mutational
hot spots so that some areas encompass and others do not encompass the UV mutational hot
spots. UV stimulated recombination over all areas at a constant UV dose was examined. Recom-
bination frequencies were elevated for all UV crosses. About UV hot spots recombination fre-
quencies were increased by a factor of two, while at the same UV dose recombination frequen-
cies about some UV mutationally silent areas were increased by a factor of 0.50. Other muta-
tionally silent areas showed higher UV stimulation of recombination. No correlation was ob-
served between map distance (0.01 to 1.00 units) and extent of UV stimulation of recombina-
tion. These results indicate that a topography of recombination in many facets reflects a topog-
raphy of mutation. The results are interpreted to indicate that recombinational events at the
fine structure level of analysis may originate by the same molecular mechanism as some
mutational events, tautomeric shifts of nucleic acid bases.

ABSTRACTS 953
Fox, A. S., I. L. MUNYON, I. P. SINGH, and E. A. SWEENEY, Michigan State University, East
Lansing, Michigan: Genetic determination, amino acid composition, and synthesis of the sez
peptide of males in Drosophila me1anogaster.-The peptide characteristic of adult males has
been purified by paper and column chromatography. Acid hydrolysis yields ten ninhydrinpositive
products. Nine of these have been identified: a-alanine, aspartic acid, ethanolamine,
glutamic acid, glycine, leucine, methionine, serine, and valine. The tenth remains unidentified.
Ethanolamine must occupy what would otherwise be the C-terminal position of the peptide
chain, or constitute a side branch through peptide linkage with one of the dicarboxylic amino
acids or through phosphate linkage with serine. Preliminary results suggest that the unidentified
residue is N-terminal.-The sex peptide first appears in males two hours after emergence. Phosphoethanolamine
is present in male third instar larvae and pupae, but not in females. This
disappears just prior to the appearance of the sex peptide, suggesting that it represents the
source of the ethanolamine in the peptide, which is synthesized during this period.-Sex peptide
is present in all 1X/2A genotypes (males) and absent in 2X/2A genotypes (females) regardless
of the presence of an intact Y, or YS or YL. Females (2X/2A) transformed into intersexual
males by the recessive third chromosome mutant transformer exhibit the peptide in the same
concentration relative to the total free amino acid and peptide pool as do normal males. Therefore,
the presence or absence of the sex peptide does not depend on the presence or absence of
one or more genes, but on the balance of sex determiners and modifiers. This conclusion will be
discussed in terms of regulatory mechanisms in protein synthesis. (Supported by grants from
the National Institutes of Health (C-2440) and the Rackham Research Endowment.)
FRYE, SARA H., 701 Atwater, Bloomington, Ind.: Concerning the X-ray dose-frequency relation
for minute chromosome changes in the yellow region in Drosophila me1anogaster.-Totals of
yellow mutants, X-ray-induced in y+ scute-8 chromosomes of mature and nearly mature sperm
ejaculated 0-2 and %4 days after irradiation), were found to exhibit approximately a linear
dose-frequency relation. The presence or absence (inactivation) of markers closely linked to
yellow was determined by genetic analyses of 98% of the 558 yellows that were able to breed
and were transmitted. Intergenic or “breakage” yellows accounted for 96-98% of the transmissible
yellows and these were roughly classified into “only minute” and “gross” chromosome
changes.-The induced frequencies of “only minutes” varied significantly below linearity with
dose, whereas those of “gross changes” varied significantly above linearity. Hence, the linear
dose-frequency relation of total yellow mutants is complex and consist of at least three presumptive
components: sublinear, linear, and supralinear. Dose frequencies of the “only minutes” did
not disagree significantly with that expected were they proportional to the 0.8 dose power. However,
dose frequencies of total minutes accorded satisfactorily with the theoretical expectation of
linearity if the total minutes included those gross yellows “capped” by a translocated autosomal
end piece and other simultaneous gross and minute yellow changes lost by aneucentricity.
Availability of a more accurate criterion of minute versus gross than the determination of which
side of bb’ the right-hand break lay on would have yielded more homogeneous classes and
sharper dose-frequency relations.-The dose-frequency criterion is more likely to be meaningful
where heterogeneities, such as germ cell treated, structure of the mutants, and others (to be
discussed) are minimal. (A.E.C. grants AT (11-1)-195 to H. J. MULLER and associates and
AT (11-1)-133 to I. H. HERSKOWITZ and associates.)
FUERST, R., and LI-CHUN LI, Texas Woman’s University, Denton, Texas.: Biosyntheses of
pantothenate homoIogs.-WAc” and GUIRARD (1948) demonstrated that mycelium of wildtype
Neurospora crassa Em5256A was able to synthesize pantothenic acid from beta alanine
and pantoyl lactone.-Extending this synthesis to possible homologs of pantothenic acid, it was
found that acetone-dried mycelium of wild-type and some pantothenicless mutants was able to
synthesize gamma pantothenate from pantoyl lactone and gamma-amino butyric acid. Under
some conditions delta pantothenate was also synthesized from delta-amino valeric acid and

954 ABSTRACTS
pantoyl lactone, but only by wild type. Other amino acids tested failed to give active compounds
when tested for growth of Lactobacillus arabinosus 17-5. Centrifuged enzyme extracts fmm
wild-type Neurospora was also active in synthesizing pantothenate and its homologs from their
precursors. The Neurospora crassa pantothenicless mutant 553 1A was able to synthesize panto-
thenate, gamma pantothenate and delta pantothenate in uitro from their precursors. Under the
same conditions the Neurospora mutant pan-ZA-74A-Y 153-M66 synthesized pantothenate,
gamma pantothenate and delta pantothenate in vivo and in uitro. The syntheses of pantothenate
and gamma pantothenate required both enzyme and coenzyme to catalyze the coupling reactions
from their precursors.-The chromatography and bioautograph investigations of gamma pantc-
thenate will be discussed.
GARBER, E. D., and T. S. DHILLON, University of Chicago, Chicago, Ill.: Aneuploidy in collinsia
heterophyl1a.-Primary trisomes of Collinsia heterophylla (n = 7) obtained from plants
treated with colchicine and from a spontaneous autotriploid were compared by (a) chromosome
associations at metaphase I, (b) transmissibility through male and female gametes, (c) fertility,
and (d) effect on vegetative and floral morphology. Trisomes from colchicine treatment were
indistinguishable and behaved as “pseudo-supernumerary’’ chromosomes; trisomes from the
triploid were distinguishable and behaved in orthodox fashion. Although the former trisomes
appeared to be replicates of the same chromosome, the latter trisomes included members of the
remaining six chromosomes. (Supported by the National Science Foundation.)
GLASSMAN, E., University of North Carolina Medical School, Chapel Hill, North Carolina:
Unexpected presence of xanthine dehydrogenase in combined extracts of maroon-like and rosy
eye color mutants of Drosophila melanogaster; a case of in vitro complementation between
nonallelic genes.-Both the maroon-like (ma-I) eye color mutant (located on the X chromosome)
and the rosy (ry) eye color mutant (located on the third chromosome) are deficient in the enzyme,
xanthine dehydrogenase. Since these genes obviously have different functions, combined
extracts of ma-1 flies and ry flies might be expected to complement each other. This has proven
to be correct; low levels of xanthine dehydrogenase activity can be detected in the combined mutant
extracts, whereas the individual mutant extracts have no detectable activity under the same
conditions. Boiled extracts have no activity. If the mutant extracts are subjected to ammonium
sulphate fractionation, then an absolute requirement is found for a heat-stable factor in the crude
homogenate. One explanation for these results is that peptide chains or enzyme polymers are
undergoing rearrangement. However, another possible explanation is that ma-1 controls the activation
of xanthine dehydrogenase while ry controls other processes (structure ?). Thus, ry extracts
provide the activating system, while ma-l provides an inactive “pro-enzyme.’’ Work is in
progress to elucidate the mechanism further in hopes of eventually understanding the basic defects
in the ma-l and ry mutants. (This work was supported by a Senior Research Fellowship
[GSF-14,911] and a research grant [RG-82021 from the National Institutes of Health.)
GLASSMAN, E.,* and J. D. KARAM,? (Introduced by MAURICE WHITTINGHILL), University of
North Carolina Medical School, Chapel Hill, N. C.: Gene dosage experiments inuolving mutants
of Drosophila melanogaster deficient in xanthine dehydrogenase.-Assays of xanthine dehydrogenase
in flies heterozygous for ry indicate that these heterozygotes have about 40-60% of
the activity of normal. Thus, the ry mutants appear to be similar to other genes in which the
heterozygote has lower enzyme activity than the wild type. On the other hand, the data obtained
from ma-l+/ma-1 heterozygotes indicate no dosage response of ma-1. This is substantiated
by the insertion of ma-1’-bearing chromosomal fragments into various diploid combinations
of ma-1’ and ma-Z. The results demonstrate that one dose of ma-1‘ produces an amount of
xanthine dehydrogenase activity which is equal to three doses of mad+, even in the presence
of ma-1.-One might conclude from this that ry might be a structural gene for xanthine
dehydrogenase while ma-l is a regulator gene. However, the fact that the ma-Z locus does have

ABSTRACTS 955
mutants which form a CRM, and which show in uiuo complementation, is not consistent with a
repressor hypothesis. A more likely possibility is that the ma-1 locus controls the activation d
the already formed xanthine dehydrogenase molecule. Thus, the CRM found in ma-1 could
represent a prmenzyme of xanthine dehydrogenase awaiting activation. The possibility that ry
is a structural gene must await further verification. (Supported by a research grant (RG-8202)
of the National Institutes of Health.) 1Senior Research Fellow (GSF-14,911) of the National
Institutes of Health. 2Predoctoral Trainee of Genetics Training Grant (2G485) of the National
Institutes of Health.
GOODMAN, HAROLD O., C. NASH HERNDON, HUGH B. LOFLAND, THOMAS B. CLARKSON, and
ROBERT W. PRICHARD, Bowman Gray School of Medicine, Winston-Salem, N.C.: Thiamine deficiency
in two breeds of pigeons.-Inbred White Carneau pigeons on the same synthetic rations
as Show Racers develop signs of thiamine deficiency (opisthotonus). Further study of the phenomenon
has shown that mean days to opisthotonus on a force-fed thiamine-free diet are 13.4
for White Carneaux and 22.2 for Show Racers. The greater genetic variability in Show Racers
is evidenced by their significantly greater variance in days to sign. F, and F2 birds are intermediate
to the parental strains. Work with liver and brain homogenates indicates that breed
differences in days to opisthotonus are not due primarily to differences in the metabolism of pyruvic
acid, alpha ketoglutaric acid, or to transketolase activity. Other thiamine-requiring metabolic
pathways are being investigated. (Supported by research grants H-5277 and H4352 from
the National Institutes of Health.)
GOWEN, JOHN W., and JANICE STADLER, Iowa State University, Ames, Iowa: Effects of acute
irradiation on number of young and litters born for mice of different strains.-Average lifetime
productivities of males and females, receiving only spontaneous irradiations and mated singly
throughout their life-spans, were 45 and 41 young, respectively. The average young for the
males increased but not appreciably as the dosages of whole body 250 pkv X rays received, advanced
from 0 to 20, to 80 to 16Or. 2Or caused an appreciable decrease, 33 percent in the progeny
for the females. Productivity was down to 87 percent at 80r and approached zero young by 320r.
Males irradiated at 320r had only a 15 percent reduction in their progeny and approached zero
young only after receiving 6Mr. Males have sired 24 litters. Again males receiving 160r or less
whole body irradiation had comparable numbers of litters. Litters decreased beyond 160r. With
480r the sire treated group litters were generally reduced to two with a slow decline ih litter
frequency thereafter to 12 litters. 640r limited the productivity tco a few first litters. Profound
differences were again noted between the sexes. Irradiated females showed reductions in late
breeding life when exposed to 20r and extreme litter decreases when exposed to 80r. Potential
egg cells in mice 40 days old were as susceptible to X rays as almost any cells known. Decrease
in fertility was accompanied by both a reduction in average numbers of litters and numbers of
young per litter. Strain differences and transmission of radiation susceptibilities will be discussed.
(This work has received assistance from Contract AT(11-1) from the Atomic Energy Commission.
Journal Paper No. 54363 of the Iowa Agricultural and Home Economics Experiment Station,
Ames, Iowa. Project No. 1180, 1187.)
GRAHN, D., KATHERINE F. HAMILTON,
and W. P. LESLIE, Argonne National Laboratory, Ar-
gonne, Ill.: Analysis of linkage between qualitatiue and quantitative traits in mice.-A previous
report (GRAHN, Genetics 43:835-843, 1958) demonstrated an association between the albino
locus and acute radiosensitivity in the F, generation of the BALB/c:C57BL/G cross and both
the F, and F, showed clear evidence of dominance for radioresistance. Six generations of recurrent
backcrossing to the low parent, BALB/c (P,), have been accomplished and the LD50,30 values
for whole-body exposure to 200 kvp X rays were determined. Interallelic additivity combined
with intra-allelic dominance of resistance for genes controlling radiosensitivity are indicated by
the data.-Starting with the second backcross generation, nonalbino and albino families werp

956 ABSTRACTS
separately backcrossed and tested. LD,, values for the albino family are expected to fit the rela
aP b
tion: LD,, = P, + - + - , where a is the linked portion of the difference F, - PI, b is the
2n-1 2n
independent portion, n is generation number and p is recombination frequency. LD,, values for
b
nonalbino segregants of the nonalbino family equal P, + a(l-p)n + -. Solution of the two
2n
equations to minimize the residual variance gives a value of 0.21 for p, when a and b are, respectively,
31% and 69% of F, -PI.-An alternative solution for p involves observed differences
between LD,, values for the albino and nonalbino families of any two backcross generations and
does not require estimates of a and b. The equation is:
P(23-1-2e-lk) $2-2 [k(l-p)S- (l-p)T] =o,
where k is the ratio of family differences for the rth and sth generations. The method is im-
precise since the solution is extremely susceptible to sampling fluctuations of k, but may be useful
if well-determined data of only two or three backcross generations are available. (Work supported
by the U. S. Atomic Energy Commission.)
GRELL, E. H., Oak Ridge National Laboratory, Oak Ridge, Tenn.: The dose efieci of mad'
and ry+ on xanthine dehydrogenase actiuity in Drosophila me1anogaster.-That mutations at two
loci, ma-l and ry, cause an absence of xanthine dehydrogenase activity has been known for
several years (FORREST, GLASSMAN and MITCHELL 1956). Studies of gene dosage from comparisons
of +/+ with ry/+ or +/+ with mu-I/+ indicate that xanthine dehydrogenase activity
is greater in the +/+ for both the ry locus (GLASSMAN and MITCHELL 1959; HUBBY and FOR-
REST 1960) and for the ma-l locus (HUBBY and FORREST 1960).-The study reported here utilizes
chromosome duplications and deficiencies produced for the purpose by X-irradiation. For
the sex-linked locus, mad+, xanthine dehydrogenase activity of ma-l+/ma-P, ma-l+/deficiency
and ma-l'/ma-l'/duplication ma-l' females and mad' and ma-l+/duplication mad' males
were measured using the methods described by HUBBY and FORREST (1960). No significant differences
in enzymatic activity per milligram of protein were detected among the yarious doses
of ma-1'. The difference between +/+ and +/mad (HUBBY and FORREST 1960) was not present
in the material that was tested. The dosage of mad' does not appear to be a limiting factor
in the quantity of enzyme activity as one dose is sufficient to give maximum activity.-On the
other hand, varying the dose of ry+ does effect xanthine dehydrogenase activity. Flies with one
dose of rf (ry+/deficiency) have much less and those with three doses (ry+/ry+/duplication
ry') have more xanthine dehydrogenase than normal.-These results can be interpreted on the
basis of several models of interaction between ry+ and mud'. Perhaps the most straightforward
hypothesis is one that proposes that each locus contributes a product toward the formation of
xanthine dehydrogenase. The ma-I' gene produces a larger amount of product than the ry+ gene
so that the product of a single dose of ma-1' is sufficient for interaction with the product of at
least three ry+ genes. Since the amount of ry+ product is limiting, enzyme concentration
increases with doses of ry'.
GRELL,
R. F., Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.: The rolr
of distribuiiue pairing in secondary nondisiunciion.-Any model for secondary nondisjunction
that postulates that the exceptional progeny arise as a consequence of heterosynapsis prior to
exchange requires a decrease in X crossover frequency that is positively correlated with the
frequency of secondary nondisjunction. The effect of an unmarked, Canton-S Y chromosome on
crossing-over and disjunction has been studied in sisters with two isosequential X's and with
the following heterozygous X-inversions, sc7/+, BM'/+, 65/+, AB/+, dl49/+, and XI/+.
The normal X's show a significant distal increase, a significant proximal decrease (car to sp-a)
and a net increase in crossing-over from 67.2 to 70.1 with a Y. Tetrad analysis reveals no change
in En's (ca. 5%) but an increase in E,'s at the expense of El's. The incidence of nondisjunction
(where primary nondisjunction is < 1% in all cases) and the percentage change in recombina-

ABSTRACTS 95 7
tion, respectively, produced by the addition of a Y chromosome to the various inversion hetero-
zygotes is as follows: sc7/+ (26.3, -16.2), BM'/+ (18.5, +10.8), 65/+ (25.9, -9.7), AB/+
(29.3, +M.5), dl-M/+ (50.6, -25.3), scS/+ (19.2, f37.3). Since the effect of the Y on cross-
ing-over is not correlated with its effect on disjunction, but depends on the location of the X-in-
version, it is proposed that associations between the X and Y, that lead to exceptions, occur sub-
sequent to exchange at distributiue pairing, and that they involve only those X chromosomes
that have not participated in exchange with each other.
HARDON, JAAP J., University of California, Davis, California: Self-incompatibility and selfcompatibility
in Solanum pennellii Cor. in relation to its unilateral compatibility with Lycopersicon
esculentum Mill.-Self-incompatibility (SI) controlled gametophytically by S alleles at one
locus has been discovered in two accessions (hereafter designated as SI S.P.) of Solanum pennellii.
The original living accession (SF S.P.) is completely self-fertile (SF). Pollen tubes of
incompatible matings cease growth in the uppermost 3 mm of styles. All three collections can be
hybridized with Lycopersicon esculentum but only with the latter as female parent. All individuals
of F, and F, L. esculentum x SI S.p. exhibit the strict SI of the pennellii parent. Each
F, consists of two intercompatible classes. In all preceding aspects the behavior is the same as
that of hybrids between L. esculentum and SI species of Lycopersicon. F, L. esculentum x SF
S.p. is self-fertile and a backcross to SI S.p. segregated approximately 1 SI: 1 SF. These and other
results support LEWIS and CROWE'S (1958) model of stepwise mutation leading from SI (as in
SI S.P.) via intermediate SF (as in SF S.P.) to SF (as in L. esculentum).-The following facts
bear on the relationship with unilateral crossing behavior. No plants of F, or F, L. esculentum x
SI S.p. were compatible as staminate parents with any SI S.p. nor as pistillate parents with L.
esculentum. The first backcross (30 plants) of the same hybrid to SI S.p. behaved in the same
fashion. The results suggest that the unilateral barrier is regulated to some extent by SI but also
by additional, perhaps polygenic, control. (Support by grant G-10704 of the National Science
Foundation is acknowledged.)
HAWTHORNE, D. C., University of Washington, Seattle, Wash.: Supersuppressors in yeast.-
Cases are known in Drosophila, Neurospora, and bacteria in which the effects of mutant genes
at two or more loci are suppressed by a single suppressor gene. In yeast, Saccharomyces cereuisiae,
several supersuppressors have been found, each with a nearly identical action spectrum
which includes mutants for adenine, arginine, histidine, isoleucine, leucine, lysine, tryptophane,
tyrosine, and uracil requirements and a genetic petite condition. Although not locus specific,
therefore, the suppressors are specific in that they will restore to normal or near-normal the
mutant character associated with only a fraction of the different heteroalleles at a given locus.
Altogether the super-suppressors suppress the phenotypic expression of about one fourth of all
the genes examined. Because of the frequency as well as the diversity of the suppressible mutants
it is thought that these mutants might well represent a class of enzyme aberrations which
would respond to some slight change in the physiology of the cell caused by the suppressor gene.
HECHT,
A., Washington State University, Pullman, Wash.: Znactiuation of an incompatibility
substance by means of high temperature treatments.-Under normal field growing conditions
as well as under similar conditions in the laboratory it has been observed that pollen tubes of
Oenothera organensis do not even enter the tissues of stigmas which have been self-pollinated.
Pollination with genetically compatible pollen results in the germination of many more of the
pollen grains and their easy penetration into the tissues of the stigma and style. Earlier experi-
ments involving stylar grafts have indicated that the inhibition of the incompatible pollen oc-
curs both in stigma and style, but that the reaction is strongest in the stigma.-If styles are ex-
cised at their junction with the ovary, and are then treated at temperatures just below what will
kill their sells (5Oo-57"C), some change occurs reducing the intensity of the incompatibility
reaction: after approximately five minutes at this temperature, whether the styles are immersed

958 ABSTRACTS
in warm water or in moist air at these temperatures, it has been found that a number of the
otherwise incompatible pollen grains will germinate and grow through the stigma and well into
the style. These treatments have not resulted in as much growth as occurs in compatible pollina-
tions, but further experiments are projected in an effort toward improving their effectiveness. A
marked difference in the effectiveness of warm tap water as compared to warm distilled water
suggests a possible influence of dissolved substances. (Supported by a grant from the National
Science Foundation.)
HENNEN, SALLY, (Introduced by ROBERT BRIGGS), Indiana University, Bloomington, Ind.: The
transfer of diploid nuclei between Rana pipiens and Rana pa1ustris.-Diploid hybrids resulting
from crosses between Rana pipiens and Rana palustris form normal viable larvae. However, the
development of the androgenetic haploid hybrids is considerably more deficient than that of
androgenetic haploids of either species. In order to determine whether this deficient development
is the result of a nucleocytoplasmic incompatibility which is not expressed in the ordinary diploid
hybrids, diploid nuclei from normal pipiens blastulae were transplanted into enucleated
palustris eggs. The resulting artificially produced hybrids expressed a greater degree of differentiation
than that observed for the comparable androgenetic haploid hybrids but nevertheless
developed abnormally. Although some formed feeding larvae, none were viable.-Having established
the fact that diploid pipiens nuclei and palustris cytoplasm are incompatible in the sense
that they cannot interact to produce normal viable larvae, the question arose as to whether this
incompatibility leads to stable changes in the developmental properties of the nuclei. This point
was tested by sacrificing some of the artificially produced diploid hybrids at blastula stages for
transfers of their nuclei back into enucleated pipiens eggs. The majority of these “back-transfer’’
embryos developed normally. Several were raised through metamorphosis at which time they had
the appearance of typical pipiens froglets. Thus, the incompatibility between pipiens nuclei and
palustris cytoplasm does not lead to irreversible changes in the capacity of diploid pipiens nuclei
to promote normal development when returned to their own type of cytoplasm following several
divisions in palustris cytoplasm. (This investigation was supported by research grant RG5850
awarded to Indiana University by the Research Grants Division of the U.S. Public Health
Service.)
HERNDON, C. NASH, HAROLD 0. GOODMAN, THOMAS B. CLARKSON, HUGH B. LOFLAND and
ROBERT W. PRICHARD, Bowman Gray School of Medicine of Wake Forest College, Winston-
Salem, N.C.: Atherosclerosis resistance and susceptibility in two breeds of pigeons.-Inbred
White Carneau pigeons used for squab production have been found to have spontaneous
atherosclerosis that closely resembles human atherosclerosis histologically, pathologically and
biochemically. In older pigeons, lesions are complicated by ulceration and thrombus formation
resulting in myocardial infarction as in the human disease. Show Racers raised on the same
rations have a low prevalence of atherosclerosis. Preliminary observations of the prevalence
and severity of lesions in F, and backcross offspring of the two breeds suggest a polygenic
mechanism with dominance of factors for resistance. The effects of dietary alterations in fat,
protein, carbohydrate and cholesterol on atherosclerosis differ in the two breeds. Resistance to
thiamine deficiency parallels atherosclerosis resistance in the two breeds, but available evidence
suggests the two traits are independent. (Supported by grants H-5277 and H-4352 of the
National Institutes of Health.)
HILDRETH, P. E., and J. C. LUCCHESI, Lawrence Radiation Laboratory and Department of
Zoology, University of California, Berkeley, Calif.: Low incidence of polyspermy in Drosophila
melanogaster and Drosophila uiri1is.-Contrary to the widespread belief that polyspermy is a
normal characteristic of fertilization in Drosophila, evidence was obtained indicating that, as a
rule, only one sperm is present per fertilized egg in the two species investigated. Feulgenstained
whole mounts of freshly laid eggs were examined. In D. nelanogaster, 96 eggs were

ABSTRACTS 959
found in meiotic stages; among these, 91 had a single sperm, two had two sperms, and three
had no visible sperm. Among 127 eggs of D. virilis, 87 eggs had a single sperm, no sperm was
visible in 40 eggs, and no case of polyspermy was observed. The possibility was investigated
that soon after their alleged entry into the egg, the supernumerary sperms undergo some
degenerative change which prevents their detection with the Feulgen technique. Drosophila
melanogaster eggs, fertilized by H3-thymidine labeled sperms, were collected; these eggs were
sectioned, stained with Feulgen or Azur-eosin Giemsa, and processed for autoradiography. At
the time of writing of the abstract, 40 eggs have been examined; the autoradiographic data
also indicate that polyspermy is a rare event in D. melanogaster. (Research performed under
the auspices of the U.S. Atomic Energy Commission.)
HINTON, C. W., University of Georgia, Athens, Georgia: Another interchromosomal effect
on crossing-over in Drosophila meLanogaster.-The mutant c3G, when homozygous, virtually
eliminates crossing-over. It has been found that the third chromosome bearing this mutant
exerts, when heterozygous, an interchromosomal effect on crossing-over comparable in magni-
tude to that of the multiply inverted chromosomes Ubx and SM5. Analysis of T-point X
chromosome testcross data (N = 10676) from females of the genotypes +/+, +/c3G, +/Ubx
and c3G/Ubx shows that while regional responses to +/c3G and +/Ubx are quantitatively
different, their combined effects are approximately additive for five of the six regions. Tetrad
analysis suggests no significant differences between the effects of the c3G and Ubx chromosomes;
double and triple exchange frequencies are increased in both cases. Similar relations are indi-
cated for c3G and SM5 in less extensive data.-That this effect of the c3G chromosome is not
itself due to a rearrangement is shown by its presence intrachromosomally and by apparently
normal salivaries. Whether the effect is a property of the c3G mutant remains to be determined.
(Supported by grant C-3000 from the National Institutes of Health.)
HOCHMAN, B., University of Utah, Salt Lake City, Utah: Further investigation of fourth
chromosomes from natural populations of Drosophila m1anogaster.-An earlier analysis of 104
fourth chromosomes removed in October, 1960, from a wild population of D. melanogaster in
Tennessee, revealed three containing recessive lethal genes. These microchromosomal lethals,
the first detected outside the laboratory, proved nonallelic inter se but two were identical to
two different lethals of X-ray origin and the third interacted lethally with bent-Dominant, a
chromosome IV dominant visible-recessive lethal.-Sampling on an enlarged scale the following
year (at sites in Tennessee, Utah and Massachusetts) has uncovered six additional lethalbearing
fourth chromosomes out of some MO examined. Two of these six are allelic. The results
of attempts to localize all of the lethals, as well as the classification of the nonlethal chromosomes
with respect to viability will be reported.-The following tentative conclusions seem warranted:
(1) Microchromosomally based lethals may be carried in gene pools of wild populations at
frequencies higher than expected considering the paucity of loci in this autosome. (2) Different
populations may be characterized by rather dissimilar frequencies of these lethals (2-3 percent
in two Tennessee populations as compared to 0.5 percent at the Utah site). (3) In contrast to
what is found in the larger autosomes, very few (< 10%) of the lethal-free fourth chromosomes
carry factors which depress the viability of homozygotes below the normal range.
HORIUCHI, T., S. HORIUCHI, and A. NOMCK, University of Oregon, Eugene, Ore.: A heatsensitive
regulatory system.-A variant of the K-12 strain of E. coli called E103 has been
obtained which to a first approximation behaves like an inducible strain for P-galactosidaseformation
at lower temperatures of incubation, and like a constitutive strain at higher temperatures
(HORIUCHI, HORIUCHI and NOVICK, J. Mol. Biol. 3: 703, 1961). p-galactosidase extracted
from E103 is similar in Michaelis Constant and heat sensitivity to the enzyme of normal strains.
The operator gene (JACOB and MONOD, J. Mol. Biol. 3:318, 1961) of this strain is normal, showing
repressibility in heterogenic cells containing a normal regulator gene. The result of an

960 ABSTRACTS
experiment using p-galactosidase formation in newly formed heteromerozygotes (PARDEE,
JACOB and MONOD, J. Mol. Biol. 1:165, 1959) was consistent with the expectation that a heatsensitive
repressor was present in the strain E103. Some characteristics of the heat-sensitive
repressor will he discussed.
HOROWITZ, N. H., HELEN MACLEOD, MARGUERITE FLING, and C. RONALD SCOTT, California
Institute of Technology, Pasadena, Calif.: Tyrosinase synthesis in resting mycelium of Neuro-
spora crassa.-Wild-type Neurospora makes little or no tyrosinase while growing in minimal
medium, but forms the enzyme abundantly when grown under conditions of semistarvation. The
enzyme is also formed on crossing media during perithecial development and is believed respon-
sible for the melanization of perithecia and ascospores. Maximal synthesis of the enzyme occurs
when mycelium grown in minimal medium is dissimilated in phosphate buffer at pH 6. Such
cultures contain no tyrosinase initially, but after standing 48 hours in buffer, up to five percent
of their extractable proteins can he accounted for as tyrosinase. The enzyme has been isolated in
crystalline form from such cultures (Cold Spring Harbor Symposia Quant. Biol. 26:233, 1961).
-The resting mycelial system is convenient for studying the synthesis of tyrosinase. The syn-
thesis requires oxygen and is inhibited by divalent cations at 0.01 M, glucose, actinomycin D,
and by a nucleic acid preparation from Neurospora. It is not affected by chloramphenicol or
puromycin. It shows an optimum at pH 6. At pH 8.2, no tyrosinase synthesis occurs,
even after the mycelium is transferred to fresh buffer at pH 6. This effect is caused by the ex-
traction, at pH 8 and higher, of substances essential for synthesis of the enzyme. If the extract
is adjusted to pH 6 and added back to the extracted mycelium at the same pH, enzyme produc-
tion is restored. The extract can he largely replaced by a mixture containing amino acids and
copper, hut such a mixture cannot account for the activity of the extract. The nature of the
active material is under investigation.
HOUSE, VERL L., and VIRGINIA YEATTS, Ohio State University, Columbus, Ohio: Selection for
modified expression of the cubitus interruptus gem in Drosophila me1anogaster.-Eight generations
of selection for increased and decreased interruption of the fourth longitudinal vein (L,)
in a stock of Drosophila melanogaster homozygous for the recessive gene cubitus interruptus
(ci) resulted in the formation of High and Low lines having significantly different degrees of
penetrance and expressivity. Penetrance in the High line averages between 95% and 100%
and has remained fairly constant from approximately the sixth generation of selection. The
Low line. however, was still characterized in the ninth generation by variations in penetrance
from 38% to 82% in a series of single-pair replications. Continued selection in the Low line
through the 20th generation resulted in the formation of additional lines having penetrance
values intermediate to those characterizing the Low and High lines. Some of these intermediate
lines were unstable and give rise to stable Low lines similar to the parental Low line. The
rapidity with which the original High line was established and the one-generation formation
of Low lines from unstable intermediate lines suggest that the difference between the High and
Low lines may involve segregation at a single major modifying locus. The truncated frequency
distributions characteristic of the High and Low lines are assumed to be the result of the interruption
of normal curves of vein-forming potentiality by thresholds for minimal and maximal
fourth vein formation. The results for females at 26°C of interline, F, and backcross matings are
compatible with the hypothesis of additive action on the transformed scale of the gene difference
or differences distinguishing the two lines.
HOWE, H. BRANCH, JR., Department of Bacteriology, University of Georgia, Athens, Georgia:
A gene decreasing ascospore yield in Neurospora tetrasperma.-During an inbreeding experiment
to develop isogenic strains, eight lines were established from random single ascospore cultures
isolated from the Dodge secondarily homothallic 16387 wild-type strain. Four of the lines
were selected for high fertility and four for low fertility based on ascospore yields. Twelve suc-

ABSTRACTS 961
cessive generations of single ascospore isolations were made in each line with concurrent selection
maintained. Since each ascospore is usually heterokaryotic for mating type, the method provided
as easy means of making repetitive intra-ascus crosses.-One of the low fertility lines showed
in the fifth and successive generations a very marked decrease in the number of ascospores
ejected. After 12 generations of inbreeding, the two mating types of this low yielding strain and
those of a high yielding strain were isolated by conidial plating.-Tetrad and backcross analyses
were made on these two high and two low yielding strains with yields being measured by
spectrophotometric readings of ascospore suspensions. Strict quantitative inheritance was not
found but rather a locus segregating independently of the mating type factors. This locus does
not prevent production of viable progeny as do the d, E and I lethals of Dodge but instead lowers
the yield, the few ascospores that are ejected being capable of germination. (Supported by Na-
tional Science Foundation Grant G-13267.)
Hsu, K. S., Stanford University, Stanford, California: Genetic basis of drug-resistant mutants
in Neurospora.-Strains resistant to acriflavine, actidione, and caffeine have been obtained which
arose by mutation of chromosomal genes. These provide a useful new class of markers in Neuro-
spora.-Among the acriflavine-resistant mutants, one allele has been recovered at the acr-I locus
in the left arm of linkage group I. This confers resistance to 2 pg per ml of the dye. Mutants
resistant to 10 pg and 50 pg per ml have been obtained at the acr-2 locus, which is the first
marker to be located in the left arm of group 111. Actidione-resistant mutants have been assigned
to two loci: act-I near al-2 in IR, and act-2 in VR. All are resistant to 10 pg per ml of the anti-
biotic. Resistance to 0.25% caffeine is conferred by gene caf-1 in linkage group V.-With the
exception of two acriflavine-resistant mutants, which were picked up during serial subculture on
acriflavine-containing minimal medium, all of the mutants were recovered by plating conidia
from conidiating colonial strains (cr cot, cr cot ylo, cr rg, or cr bal) on Vogel's minimal medium
plus the drug, at concentrations such that no growth was observable when 106 to 10' conidia
from the sensitive strain were plated. UV-irradiation giving 50-75% killing was applied in some
cases. Scoring for resistant us. sensitive is clear-cut for all of the three categories of mutants.
(Supported by Public Health Service research training grant 26-158.)
HUANG, P. C., S. EMERSON, and MARY R. EMERSON, California Institute of Technology, Pasadena,
Calif .: Synthesis of heterokaryons involving a plasmodioid (slime) variant of Neurospora
crassa, and isolation of their nuclear components.-The UV-induced plasmodioid variant, slime,
of N. crassa is characterized by a Physarum-like morphology and is deficient in the cell wall.
Its presumptive parent, Stanford 1207-1A, had five markers in the mating type chromosome:
A, arg-2, cr, aur and os. The slime isolate retained the specific requirement for arginine and,
though outcrosses to wild type were highly infertile, the five marker genes of 1207-1A segregated
in the expected combinations and proportions. Three genes, os and two new mutants, are
necessary but not in themselves sufficient for the production of the slime phenotype. Heterokaryons
were used in the present study to detect a possible cytoplasmic factor. A heterokaryon
was established between slime and Stanford strain 1413-2A carrying A, lys-3, nic-I, al-2 and OS
in the mating type chromosome. Under these heterokaryotic conditions the wild-type alleles of
al-2 and aur complement in the production of carotenoid pigments and those of lys-3 and nic-1
with arg-2 for growth. The inhibition of lys-3 mutants by arginine and of arg-I mutants by
lysine was made use of in observations on the heterokaryons and their isolates under a variety of
conditions. The results support the inference that the slime character is determined solely by the
nucleus. Special techniques will be discussed and observations will be exemplified with slides.
HUBBY,
J. L., University of Chicago, Chicago, Illinois: Protein differences in DrosophiZa.-
Analyses of ammonium sulfate fractions of the soluble protein in Drosophila have been made
utilizing acrylamide gels as a supporting medium for zone electrophoresis. Several differences in
migratory rates of proteins in strains of Drosophila melanogaster carrying genetic markers have

962 ABSTRACTS
been demonstrated. Genetic and biochemical studies of these differences will be presented. Utili-
zation of this technique for physiological and developmental genetic analysis will be discussed.
(Work supported by a grant from the National Science Foundation.)
HUFF, SALLY D., Roscoe B. Jackson Memorial Laboratory. Bar Harbor, Maine: A genetically
controlled response to the drug chlorpromazine.-Establishment of genetic bases for differences
in behavioral and physiological sensitivity to drugs provides an excellent opportunity to investigate
the biochemical mechanisms involved in specific responses. At the same time, information
regarding physiological gene action can be obtained. This approach has been taken in a study
of the psychoactive phenothiazine derivative, chlorpromazine. Subjects were adult mice of both
sexes from C57BL/6J, DBA/2J, IVHeJ, and C3HeB/FeJ inbred strains and all possible hybrids.
Doses of 0, .5, 1, 2, and 4 mg CPZ/kg body weight were administered intraperitoneally one hour
before a 200-second test in a photoelectric activity apparatus. Results show differential sensitivity
of genotypes superimposed on a general depressant effect. With 4 mg/kg, 90% of C57BL/6J
animals failed to respond in the activity test, whereas only seven percent of C3HeB/FeJ mice
exhibited no activity. A/HeJ and DBA/2J mice showed complete depression in 62% and 67%
of the individuals, respectively. Results from the hybrids indicate that a simple genetic mechanism,
possibly involving no more than two loci, could be responsible. Preliminary experiments
to determine dose dependency and physiological characteristics of the response indicate: (1) the
difference between C57BL/6J and C3HeB/FeJ mice is clearly observable over a wide range of
doses; (9) following one injection, C57BW6J mice are partially refractory to additional doses for
periods up to one week; and (3) the degree of ataxia produced by 4 mghg is similar in C57BL/6J
and C3HeB/FeJ mice, suggesting a sensory or motivational basis for the difference in spontaneous
activity. Further genetic studies and biochemical investigations are in progress. (Supported in
part by PHS grant MY-1775 from the National Institute of Mental Health.)
HUGHES, R. D., and W. J. GEERAETS, Medical College of Virginia, Richmond, Va.: Extreme
microphthalmia in the Syrian hamster.-This mutant of spontaneous origin was obtained from
a local hamster fancier. It behaves as an autosomal recessive with complete penetrance and with
minor variation in expression in adult animals. Preliminary histological studies seem to indicate
that this ocular anomaly becomes apparent shortly before, or at term (16 days) with normal
development up to that time. First notable changes appear as slightly reduced size of the globe
compared with normal animals of the same age. During the first two to four weeks after term,
lenticular and retinal changes become manifest and progressively more severe with time. Extreme
microphthalmia, or in some instances only remnants of tissue faintly resembling ocular
structures could be observed in sexually mature or older animals. A white coat (albinotic?) is
always found in association with “blind.” Other observable pleiotropic effects of this mutant are
(1) a disturbance in the reproductive system of the female resulting in marked hemorrhaging
during parturition, and (2) extreme nervousness. Both affected males and females are fertile
and offspring can be obtained, although with some difficulty.
HURST, D. D., and S. FOGEL, Brooklyn College, Brooklyn, N.Y.: Meiotic and mitotic recombination
among centromere-linked genes in Saccharomyces.-A red diploid of Saccharomyces,
homozygous for ad-I, and containing seven heterozygous centromere-linked markers and two
heterozygous noncentromere-linked markers including ad-6 was constructed. Meiotic map distances
for these markers have been reported by HAWTHORNE and MORTIMER (1960). In effect,
the ad-l/ad-I, Ad-6/ad-6 genotype provides a visible means for the detection of any mitotic
recombinational event proximal to the ad-6 locus. The meiotic map distances as ascertained by
ascus dissection of untreated material were compared to meiotic and mitotic distances obtained
from an ultraviolet irradiation series. In general, the observed meiotic map distances in both
treated and untreated material were in accord with the published maps. To a first approximation,
the frequencies of mitotic recombination were proportional to the meiotic gene-centromere dis-

ABSTRACTS 963
tances. For genes more than 25 map units from the centromere, mitotic recombination rates rise
linearly with UV dosage. However, for markers less than 15 units from the centromere homo-
zygosis frequencies via mitotic recombination attain saturation at low UV doses. (This work has
been supported by NIH grant #RG-6979.)
HWANG, Y. L., E. SHULT, G. LINDEGREN, and C. C. LINDEGREN, Southern Illinois University,
Carbondale, Ill.: The chromosome maps of Saccharomyces.-The chromosome maps of Saccharomyces
have been recently extended and new relationships of centromeres, sites of affinity and
gene loci have been demonstrated by hybridizing cultures from a variety of sources including
mutants from Japan, Italy, and California.-The map of Saccharomyces shows ten centromeres,
four sites of affinity and four linkage groups not assigned to known centromeres or affinity sites.
One of the ten centromeres specified by the centromere marker met3 is newly identified. Three
of the affinity sites exhibit preferential segregation with chromosome V, and the fourth affinity
site shows nonrandom assortment with chromosome VIII. Twentytwo gene loci have been
newly located. The data previously reported by LINDEGREN, et al., by HAWTHORNE and MORTI-
MER, and by OSHIMA comprise a total of 57 gene loci.
IVES, P. T., and G. R. FINK, Amherst College, Amherst, Mass.: Comparison of translocation
and crossover chromosomes produced by y irradiation of Drosophila males.-Translocations
(Ts) of chromosomes 2 and 3 were derived from days 5 and 6 sperm of Oregon-R/rucuca males
and crossovers from days 9 and 10 sperm, using an exhaustive mating schedule at 25°C after
two kr. Tests showed homozygous lethality in 84 of 102 Ts and in 24 of 105 non-T second
chromosomes also derived from days 5 and 6 sperm. The estimated lethality due to a T is .35
of a lethal for each of its two chromosomes, with 2.7 T lethals to one non-T lethal per chromosome.
In contrast 11 of 141 crossover chromosomes appearing in males and ten of 172 noncmssover
sibling third chromosomes from days 9 and 10 sperm were recessive lethals, the
difference in these two frequencies being nonsignificant (P = .6) .-The lower lethality in
crossovers us. Ts and the absence of a comparable increase in proportion of lethals in crossover
chromosomes support the views that induced crossovers and Ts are genetically different at their
exchange sites (PATTERSON and STONE 1934) and that if both result from induced chromosome
breakage then lethality arises not from this breakage but probably from a position effect of genes
not themselves affected by the irradiation. (Earlier comparable studies were rendered uncritical
by the later discovery of widely divergent induced mutation frequencies at different spermatogenic
stages.) A difference between induced male and normal female crossingover is still ap parent in their very different proportionate chromosomal distributions. (Supported by Contract
No. AT(30-1)2467 from the U.S.A.E.C.)
IYENGAR, SHANTA V., and RACHEL M. BAKER, Louisiana State University, Baton Rouge, La.:
The influence of temperature on the pattern of insemination by Drosophila melanogaster males9
-Three groups of 20 young Drosophila males from each of two different stocks were treated as
follows: group 1, untreated controls; group 2 and 3 males subjected to 36°C and -8°C respectively
for 15 minutes immediately prior to mating. Each male of the first type was placed
with three virgin females for a day and replaced by the second type male for the next 24 hours
after which the females were individualized and transferred to fresh vials daily for ten days.
The total offspring for groups 1, 2, and 3 were respectively 2578, 3419, and 849 indicating
about a 30 percent increase in group 2 and about a 66 percent decrease in group 3. None of
the females in groups 1 or 3 were fertilized by both males, while in group 2, 10.9% were. The
percentage of unfertilized females in groups 1, 2, and 3 were respectively 27.11%, 7.27%, and
71.4%. While a cold “shock” impairs the physical activity and therefore the fertility of the male,
a mild heat “shock” seems to enhance, rather than impair, the fertility of the male due to one
or several of the following: (1) accelerated spermatogenesis, (2) larger number of sperm per
ejaculate, (3) increased motility of the sperm in the male, as well as in the recipient female as

964 ABSTRACTS
is indicated by the F, counts for the first two-day period: 11.5% for group 1, 46.4% for group
2, and 10.8% for group 3. (This work was supported by a research grant from the Graduate
Research Council of Louisiana State University to the senior author and an undergraduate
research grant from the Louisiana Heart Research Fund to the junior author.) 1The initial
phase of this work was presented at the 1961 Meeting of the Louisiana Academy of Sciences.
KAMRA, OM P., and SAROJA K. KAMRA, Department of Plant Science, The University of Manitoba,
Winnipeg, Man., Canada: Some cytogenetic, biochemical and radiobiological investigations
in Haplopappus gracilis.-Individual chromosomes of Haplopappus gracilis (n = 2) can be
easily recognized in most stages of mitosis and meiosis. The two larger chromosomes are metacentric,
each about 8 p in length. The other two are acrocentric, each about 6.3 p long, possessing
one nucleolar organizing region. H. gracilis is therefore an interesting organism for studying
chromosome breakage and reunion following a physical or chemical mutagenic treatment.
Radiation-induced translocations between the nonhomologous as well as the homologous chromosomes
can be easily recognized at mitosis. However, the different translocation heterozygotes
behave in an identical manner at meiosis in forming only one ring of four chromosomes involving
the entire genome regardless of the sites of the translocations. Currently available H. gracilis
populations are extremely heterozygous, thus restricting its use in mutation research.-Interspecific
and intraspecific crosses can be made readily, and individual plants are capable of
vegetative propagation through cuttings. Leaf, stem and root tissues have been cultured successfully
on nutrient-agar media. Seed germination requires exposure to light. The diurnal opening
and closing of inflorescences show a complex photoresponse depending upon, among other factors,
light intensity and photoperiod.-Seeds of H. gracilis contain 15 percent oil rich in the unsaturated
fatty acids, linoleic (63%), oleic (14%) and palmitoleic (8%) acids. It also has a
fair amount of palmitic acid (1 1 %) . H. gracilis possesses several nuclear characteristics which
are generally associated in many species with sensitivity to ionizing radiations. H. gracilis,
however, was found to be fairly tolerant to acute X-ray exposures up to 44,000r.
KAPULER, ALAN M., (Introduced by NORMAN H. GILES), and HARRIS BERNSTEIN, Yale University,
New Haven, Conn.: The relationship of genetic and complementation maps.-Initially
in this work intragenic complementation between albino mutants of Neurospora crmsa was
studied. From the matrix of pairwise tests obtained with 25 mutants of independent origin, it was
possible to construct an eight unit linear complementation map. On this linear map it was necessary
to represent some of the mutants by two discontinuous line segments; that is, these mutants
were exceptions to a linear representation. However, it was found that each of the mutants could
be represented by a single continuous line if the map was made circular. It was then discovered
that the circular representation could also explain exceptional mutants at other loci. Circular
complementation maps were constructed from preexisting data for the adenine-8 locus ( ISHI-
RAWA, PhD Thesis, 1961, Yale University) and the isoleucine-valine-3 locus (BERNSTEIN and
MILLER, Genetics 46: 1039, 1961). When the genetic map of the adenine-8 locus was applied to
the circular complementation map, the two were found to be cocircular, if the genetic map was
carried through a two-turn spiral. A similar spiral was produced when the genetic map and the
complementation map of the pyrimidine-3 locus (WOODWARD, Proc. Natl. Acad. Sci. U.S. 48:348,
1962) were correlated. On the hypothesis that complementation results from the aggregation of
identical polypeptide monomers produced by a locus, it follows that the two-turn spiral formed
in the cocircular plot of the genetic and complementation maps may give a two-dimensional
representation of the polypeptide as it exists in uiuo. In addition, when the genetic map is
drawn exactly to scale, it is possible to limit further the shape of the spiral and hence, presumably,
the configuration of the polypeptide.
KELLER,
E. C., JR., Department of Botany and Plant Pathology, Pennsylvania State Univer-
sity, University Park, Pennsylvania: 1 Some components of fitness which memure genotype-

ABSTRACTS 965
environment interrelationships in Drosophila me1anogaster.-Six highly inbred wild-type lines
(two each from lines derived at 18”C, 22”C, and 26°C) were reciprocally crossed. Two types of
F, hybrids are distinguished, those from lines derived at different temperatures (intertemperature
F,’s) and those obtained from matings of inbreds derived at the same temperature (intratem-
perature F,’s). The 18 genotypes were tested along with the six parental lines at the three tem-
peratures. Egg productivity, larval survival, percent fertile males, percent fecund females, sex
ratio, and male-female developmental period were scored. True statistical interaction was
obtained in egg productivity and larval survival. In addition, from a combined index of
reproductive capacity, it appears that total reproductivity “fitness” tends to follow the pattern
of egg production. Reciprocal differences were noted in many cases, but no pattern could be
delineated for a given genotype. The most interesting finding was that no adaptive response to
the temperature selection (for at least 55 generations) was obtained in the inbreds; however, the
intratemperature F,’s were significantly superior in over-all reproductivity to the intertempera-
ture hybrids, thus indicating a certain amount of selective response which was manifest only in
the heterozygotic condition. (This work was supported by a USPHS Predoctoral Fellowship and
a USPHS Research Grant, #RG-#7-(c) .)1 Present address: Department of Biochemistry, Uni-
versity of North Carolina Medical School, Chapel Hill, North Carolina.
KELLER, E. C., JR.~, J. MCLEAN (Introduced by K. Koiima) and EDWARD GLASS MAN^, Biochemistry
Department, University of North Carolina Medical School, Chapel Hill, North
Carolina: Additional loci in Drosophila melanogaster affecting xanthine dehydrogenase.-Previous
work has demonstrated that the eye-color mutants, rosy (ry) and maroon-like (ma-1) of
Drosophila melanogaster, are deficient in xanthine dehydrogenase. A strain has recently been
discovered which has 1/10 the usual amounts of xanthine dehydrogenase. When reciprocal outcrosses
are made to wild-type, ma-1, or ry, the progeny have normal activity. This indicates
that the factor(s) for low activity is probably not allelic to ma-1 or ry. When low line females
are crossed to Pm; Sb/Xa males, and the F, males are backcrossed to low line females, preliminary
analysis of the data from assays of xanthine dehydrogenase in single flies of the four
resulting F, genotypes indicate a multigenic typ:: of inheritance involving probably the second,
third, and fourth chromosomes. (Supported by a research grant (RG-8202) from the National
Institutes of Health.) Postdoctoral Trainee under Genetics Training Grant (2G-685) of the
National Institutes of Health. Senior Research Fellow of the National Institutes of Health
(GSF-14,911).
KODANI, MASUO, Institute of Microbiology, Rutgers University, New Brunswick, N.J.: Long
term in uitro maintenance of mammalian spermatogenesis.-A method has been developed
whereby spermatogonial cells isolated from mammalian seminiferous tubules and cultured in
vitro undergo continuously for a number of months division and differentiation through spermatocyte
and spermatid stages to matured sperms. The method consists of procedures almost entirely
different from those of somatic cell cultures and the use of a specially formulated culture medium.
By this method oomplete spermatogenesis has been maintained with testicular cells of rats now
for over six months. The use of the method for cytological, biochemical and endocrinological
studies of phenomena unique to division and differentiation of mammalian germ cells and its
practical application to some problems of medicine and agriculture are briefly discussed.
KRIEG, D. R., Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.: Ethyl
methanesulfonate-induced reversion of bacteriophage T4rII mutants.-Two fairly distinct levels
of ethyl methanesulfonate (EMS) -induced revertant frequencies have been found from a group
of rII mutants. Four base analog-induced mutants gave 25-1 60 EMS-induced revertants per mil-
lion phage, while nine other base analog-induced mutants and nine EMS-induced mutants gave
only one or less EMS-induced revertants per million. These results could be expected if one
kind of purine-pyrimidine nucleotide pair transition is highly inducible by EMS and the other
kind is weakly inducible. However, not all the induced revertants represent true back-mutations

966 ABSTRACTS
to wild type; two of the highly revertible mutants each gave two kinds of revertants with dis-
tinguishable plaque morphologies. Of nine proflavine-induced mutants tested, only one was highly
EMS-revertible, and the induced revertants were not true back-mutants. The induced revertant
frequencies were measured by selective assays of progeny phage after giving extracellular phage
a standard exposure to the mutagen and allowing one cycle of reproduction in a nonselective host.
When revertible mutants were tested by selective assays of exposed phage without first allowing
nonselective reproduction, a variable fraction of the potential induced revertants was detected.
The simplified technique detected all of the revertants induced from some mutants but only 0.2
or 0.02 of the induced revertants from other mutants.
LA BAR, MARTIN, (Introduced by W. H. STONE), and M. R. IRWIN, University of Wisconsin,
Madison, Wisconsin: New interaction products in pigeon-dous hybrids.-"Hybrid substances"
are antigens which appear on the red blood cells of an individual, but not on those of its parents.
The hybrid substance of F,-Columba liuidStreptopelia risoria is presumably the interaction
product of the gene(s) for the CJ (formerly C') character of liuia (W. J. MILLER, Genetics 41:
700, 1956) and for a hypothetical contrasting entity of risoria.-Ch-8, from St. chinensis,
(formerly d-11) has been isolated by repeated backcrosses to risoria, which possesses the contrasting
character, ri-8. Similarly, 0, of C. guinea, which contrasts to CJ, has been transferred to
liuia. Reagents specific for the F,-liuidrisoria hybrid substance are crossreactive with the
ch-8/ri-8 hybrid substance.-Three new types of liuidrisoria-like hybrids, CJ/ch-8, CQ/ri-S, and
CQ/ch-8, were obtained for comparison with F,-liuidrisoria (C1/ri-8). Appropriate absorptions
of antisera to each type, with subsequent agglutination tests, show that the cells of each type
possess a hybrid substance. The four hybrid substances are serologically related, but not identical.
Reagents to each type of hybrid substance, absorbed by and tested with the cells of other types,
show that each of the four is unique.-These results indicate that the genes responsible for the
production of CQ, ch-8, and ri-8, as well as Cl, respectively, (or linked genes) interact to produce
different hybrid substances in the different combinations.
LACY, ANN MATTHEWS, Goucher College, Towson, Baltimore, Md.: Complementation and biochemical
relationships between Td mutants in Neurospora crassa.-The Td locus controls formation
of the enzyme tryptophan synthetase (TSase) which catalyzes the reaction of indole glycerol
phosphate (IGP) and serine to form tryptophan (reaction 1). TSase can also catalyze the
formation to tryptophan from indole and serine (reaction 2) and indole from IGP (reaction 3).
Over 150 Td mutants have been isolated and shown to be deficient in reaction 1. Certain mutants
complement each other in a heterocaryon to form active TSase. The results of experiments with
those mutants indicated a strong correlation between complementation groups and those groups
basnd on such differences as temperature sensitivity, ability to carry out reaction 2, or 3, and
response to suppressor genes (LACY and BONNER, Proc. Natl. Acad. Sci. U.S. 47:72-77, 1961).
-Studies of additional mutants indicate that this correlation may be more subtle than originally
postulated. For example, several new mutants accumulate indole under specific growth conditions,
yet some of these mutants do not belong to the same complementation group as the
original indole accumulators. None accumulate as much indole as the original accumulators.
Temperature-sensitive mutants belong to a complementation group distinct from those of the
above mutants. It now appears that some of these temperature-sensitive mutants also accumulate
small amounts of indole. Consequently, it would appear that the property of indole accumulation
is not characteristic of any single complementation group. Relationships between these mutants
will be discussed in terms of the structure and function of the Td locus. (Supported by a grant
from the National Science Foundation.)
LENG, EARL R., R. H. HAGEMAN,
and JOHN F. ZIESERL, University of Illinois, Urbana, 111.:
Hereditary control of nitrate-reductuse activity in mm'ze.-Highly significant differences in levels
of specific activity of the enzyme nitrate-reductase (NR) were found in a group of 12 established

ABSTRACTS 967
dent maize inbred lines assayed both in 1960 and 1961. All assays were made on field-grown
plants. With only one exception, relative levels of NR activity were similar within this set of
lines in the two years, the between-years correlation being highly significant. F, hybrids showed
NR activity levels generally intermediate between those of the respective parental lines. Different
inbred lines showed widely dissimilar seasonal patterns of NR activity levels. Generally, the
inheritance of the control of NR activity level appears to be complex; no indications of “single
gene control” or “nitrate-reductase-less” mutant forms have been found. Since this enzyme has
been shown to play an important role in the nitrogen metabolic cycle of the maize plant, it ap-
pears likely that hereditary differences in NR activity could be important in the determination of
yield levels. Further studies are in progress.
LEVINTHAL, MARK, S. FOGEL, and D. D. HURST, Brooklyn College, Brooklyn, N.Y.: Genetic
and biochemical analysis of purine biosynthetic pathways in Saccharomyces.-Nine separate
genetic blocks of adenine synthesis are known in yeast. On completely specified media all mutants
produce white clones with the exception of ad-1 and ad-2. These produce a red, pink, or
buff pigment that is influenced by other loci, especially those affecting methionine, threonine or
histidine synthesis. Doubly blocked stocks containing ad-1 or ad-2 fail to accumulate pigment.
Extracts of all single mutants, ad-1 through ad-8, have been examined for the presence of
diazotizable amines via paper chromatography and the Bratton-Marshall reaction. On the basis
of the major product accumulated, the mutants fall into five classes as follows: ad-1-AIR; ad-2,
CAIR; ad-3 and ad4, AICAR; ad-5, ad-6, and ad-7, SAICAR; add, no diazotizable amine
found. The data indicate a purine biosynthesis pathway consistent with that of both pigeon
liver, Neurospora, and microbial systems. Accumulation studies concerning multiply blocked
stocks, suppressor action and effects of known genetic modifiers are in progress. (This work has
been supported by NIH Grant #RG-6979.)
LEWIS, H. W., and H. S. LEWIS, Michigan State University Oakland, Rochester, Mich.: Zdenti-
fication of a dominant second chromosome factor regulating dopa oxidase activity in Drosophila
me1anogaster.-A dominant gene (beta) has been identified on chromosome I1 which accounts
in large measure for the low dopa oxidase activity in 20-3, a line selected for low enzyme activity
from a Samarkand strain. Crosses between the 10-3 strain and a marker strain (b cn bw) yield
testcross classes whose activities in dopa oxidase units are as follows: b cn + bw/b cn + bw and
b cn + +/b cn + bw, activities >1000; + + /3 +/b cn f bw and -?- + /3 bw/b cn + bw, activi-
ties 1000. The hi-3 strain is therefore regarded as homozygous wild
type at the /3 locus. In progeny tests of individuals representing crossovers between b and cn,
b + individuals are associated with /3 activity and all + cn individuals with non+ activity.
These tests offer evidence that the /3 locus is several map units to the right of the putative struc-
tural locus, Alpha.
LIEB, M., University of Southern California Medical School, Los Angeles, Calif.: Effect of
substances that enhance UV mutation on UV induction and on photoreactivation in lysogenic
bacteria.-Methyl purines and acridine dyes will increase the frequency of mutation when
UV-irradiated bacteria are grown in their presence. No mutants are induced in unirradiated
bacteria under the same conditions. These substances have much less effect on bacterial killing.
It has been proposed that the LJV-enhancing substances prevent a “dark reactivation” process
that repairs certain UV-induced lesions, presumably in DNA.-We have studied the effect of
post-UV treatment with caffein, acriflavin or proflavin on a nonlysogenic straih of E. coli K-12
and on lambda-lysogenic derivatives. Killing of lysogenic strains was increased 5-1OX under
conditions which increased killing of nonlysogenic strains only slightly. UV-survival curves of

968 ABSTRACTS
lysogenic bacteria in early stationary phase have a shoulder, but after 30-60 minutes post-UV
incubation in the dyes or caffein the curves became “one hit.” There was little effect on latent
period or burst size. UV bacteria growing in the presence of a W-enhancing substance remained
sensitive to reactivation by visible light.-We will discuss the possible mode of action of UV-
enhancing substances, and also the possibility that UV killing and mutation or induction involve
different photoproducts.
LOBBECKE, E. A., and D. R. KRIEG, Biology Division, Oak Ridge National Laboratory, Oak
Ridge, Tenn.: Nitrogen mustard-induced mutation of bacteriophage.-The ability of nitrogen
mustard to induce gene mutations by reaction with genetic material was investigated with phage
T4. Induced reversion of three rII mutants was tested, using a technique similar to that previously
employed for these mutants with another alkylating agent, ethyl methanesulfonate (GREEN
and KRIEG 1961; KRIEG 1962). Extracellular phage were exposed to a solution of the mutagen, allowed
to reproduce, and the progeny tested by selected assays for induced revertants. This procedure
avoids problems that complicate the interpretation of an earlier test for nitrogen mustardinduced
mutation of phage (SILVESTRI 1949). Nitrogen mustard was found to give a fivefold
increase in revertant frequency for two mutants (AP72, AP275) that are highly revertible by
ethyl methanesulfonate, and no significant nitrogen mustard-induced reversion was found for a
third mutant (AP156) which is only very weakly revertible by ethyl methanesulfonate. Both
nitrogen mustard and ethyl methanesulfonate react with DNA by alkylation of guanine
(BROOKES and LAWLEY 1962). The results indicate that the two alkylating agents are qualitatively
similar in their mutagenicity for what are presumed to be GC to AT nucleotide pair transitions,
but that the extent of its mutagenicity, relative to its phage-killing effect, is lower for
nitrogen mustard.
MAGUIRE, MARJORIE P., University of Texas, Austin, Texas: Spontaneous chromosome fragmentation
and exchange in corn-Tripsacum hybrid derivatiues-In sporocyte samples from
plants carrying corn-Tripsacum reciprocal interchange chromosomes (as well as a normal corn
chromosome 2) cytologically demonstrable, rare exchanges between the corresponding corn and
Tripsacum segments have been found. These exchanges can be interpreted as premeiotic crossingover.
Occasional small fragments and an isochromosome composed of a duplicated Tripsacum
segment have also been found. Among the sporocytes of a plant carrying a secondary exchange
involving the Tripsacum segment, in addition to increased frequency of exchange and fragmentation
of the above type, occasional exchanges between the short arm of chromosome 9 and
the Tripsacum segment occurred. Several cells carrying short knob bearing fragments from
both chromosome 9 and the Tripsacum segment were also found. There was a nonrandom tendency
for association of the chromosome 9 and Tripsacum knobs, and occasional associations were
also seen between the knob of chromosome 9 and intercalary regions of the Tripsacum segment.
Since some of the fragments were acentric, it is thought that these were formed in the meiotic
cell generation, and since whole chromosomes seemed to be involved in all cases, the events
probably occurred before these were effectively divided into two chromatids. Events which involved
nondisjunctive distribution of knob-bearing chromatids, however, must have occurred in
a premeiotic cell generation. Aleurone variegation has appeared in the stocks described above
and pericarp variegation occurred in another corn-Tripsacum hybrid derivative. Neither of these
traits was apparent in any of the corn stocks utilized. Genetic analysis of the variegations is in
progress.
MARTIN, ALBERT, JR., RONALD J. DELANKO, and FREEMAN FLETCHER, JR., Veterans Administration
Hospital, Leech Farm Rd., Pittsburgh 6, Pa.: Modified technique for staining chromosomes.Aonventiona1
techniques for staining chromosomes of leukocytes cultured from human
peripheral blood, employ a routine staining dish passage of slide or cover slip preparations
through acetic orcein, a dehydration schedule, and mounting in Diaphane or Permount. This

ABSTRACTS 969
procedure leaves much to be desired both in the retention of stain by the chromosomes, and in
the time required to obtain a permanent mount. We suggest that better staining of chromosomes
may be obtained with a simple modification of the conventional Gram stain employed in bac-
teriology. Air dried chromosome preparations on slides or cover slips are stained for 75 seconds
with one percent crystal violet, washed thoroughly in tap water, mordant with Gram’s iodine
for two minutes, washed thoroughly, counterstained for five seconds with safranin, washed thor-
oughly and air dried. The essential modification here is that no decolorization with alcohol is
employed. The air dried stained slide preparations may be observed directly under oil without
cover slip, or may be coverslipped with a drop of Permount without a dehydration sequence. With
transmitted light the chromosomes are purple to blue. With a green No. 58 filter in the light
path the chromosomes are a clear full-bodied black with little or no background evident. With
phase optics the chromosomes are a brilliant light blue with a pink background. The density of
staining and the contrast obtained with this modified Gram stain is superior to that obtained with
acetic orcein. (This investigation was supported in part by Grant No. 261-1 from the National
Multiple Sclerosis Society.)
MCDONALD, D. J., Department of Biology, Dickinson College, Carlisle, Pa.: Characteristics of
Tribolium populations in equilibrium.-Different strains of Tribolium confusum were reared in
population cages from which weekly estimates of natality, mortality and adult population size
have been made. These populations, in contrast to others previously studied, attained an equilibrium
size which was different in the two strains observed. Four populations of one strain, derived
from a recently collected wild stock and a laboratory stock, attained average sizes of 2076, 1972,
1954, and 1860 adults, and natalities (number of pupae enclosing per week) of 221, 186, 183, and
204. From these data the mean longevities were calculated to be 9.4, 10.6, 10.7, and 9.1 weeks.
Two populations of a second strain, derived from the wild stock only, and containing the eyespot
(es) mutation and its wild allele, reached average sizes of 2539 and 2388 adults. The natalities
were found to be 391 in both cages and the mean longevities are 6.5 and 6.1 weeks. It is suggested
that the higher natality found in this strain leads to the formation of larger populations in which
more adverse conditions result in shorter life spans. Since all the populations are maintained in
similar environments, dissimilarities in population parameters probably reflect underlying genetic
differences in the two strains. The only visible genetic difference was the presence of es in
the populations of the one strain at a frequency of 0.67, and since there was little change in
frequency during 130 weeks it is possible that the es mutation and its wild allele are in genetic
equilibrium in these populations. (Supported by National Science Foundation Grant G-8888.)
MCGINNIS, R. C., (Introduced by I. A. UCHIDA), Department of Plant Science, The University
of Manitoba, Winnipeg, Man., Canada: The occurrence of spontaneous aneuploids in common
oats, Avena sativa.-In an attempt to produce an aneuploid series in common oats, Avena sativa,
seedlings of foundation lines of the variety Garry were examined for chromosome number by
squash preparations of Feulgen stained root tips. A total of 4,023 seedlings were examined and
24 spontaneous aneuploids were found comprised of two nullisomics, 17 monosomics and five trisomics.
From karyotype analysis it was determined that all five trisomics are different from one
another and there are at least six and possibly eight different monosomics. Fertility was markedly
reduced for all aneuploids. Three of the monosomics and the two nullisomics were completely
sterile and were never identified. It appears probable that a trisomic series will be more easily
maintained in this species than a monosomic series. Limited data on univalent transmission indicate
wide variations between different chromosome lines.
MCNARY,
H. W., and A. E. BELL, Purdue University, Lafayette, Indiana: The effect of en-
vironment on response to selection for body weight in Tribolium cmtaneum.-Two populations
of Tribolium cmtaneum originating from the same random mating base population were cul-
tured in different environments and selected during nine generations for increased body weight

9 70 ABSTRACTS
in a replicated experiment. Levels of relative humidity constituted the difference between en-
vironments. The high level, 70% RH, was known to increase body weight by about ten percent
over the low level, 40% RH. Genetic parameters needed for predicting the direct and correlated
responses from selection on either environment were estimated in the base population. While
selection was based on the ability to perform in only one environment, each population was
tested in the opposite environment each generation.-Good agreement between predicted and
observed direct response to selection was obtained for both environments. The observed indirect
responses or correlated responses to selection did not agree well with those predicted.-Heritability
of the selected trait was about the same in the two environments (55-60%), yet the phenotypic
variance on the low environment was nearly twice that on the high environment. These pa-
rameters plus a high positive genetic correlation for body weight on the two environments will
be discussed in terms of maximum genetic improvement. (Supported by a grant from the Na-
tional Science Foundation.)
MEAD, C. G., Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.: The re-
lationship of a DNA-associated RNA with euchromatic and heterochromatic derived DNA of
Drosophila me1anogaster.-In the process of isolating Drosophila DNA free of cytoplasmic
RNA, a small fraction of RNA consistently is found associated with the DNA. The nature of this
association between DNA and RNA and its relationship with euchromatic and heterochromatic
derived nucleic acids has been investigated. The molar nucleotide ratio of the DNA-associated
RNA is identical to that of the corresponding DNA (equating U with T) but different from
that of the microsomal RNA. The ratio of the DNA to its associated RNA is found to be 2:l.
The RNA is sensitive to both alkaline hydrolysis and ribonuclease digestion. A study of the rate
of incorporation of P32 orthophosphate into the nucleic acids of ’third instar larvae demonstrates
that the DNA-associated RNA incorporates phosphorus at a much higher rate than the micro-
somal RNA. Ultracentrifugal studies demonstrate a marked increase in the sedimentation ve-
locity of the associated DNA after removal of the RNA with ribonuclease. The melting tem-
perature (T,) of the associated DNA is increased as a result of ribonuclease digestion. These
data are interpreted as evidence of a DNA-RNA complex. The RNA of this complex exhibits
many of the properties of “messenger RNA.” Samples of these nucleic acid fractions derived
from adult males that were coisogenic except for the presence or absence of a Y chromosome
have also been examined. The DNA-associated RNA from XO and XY males exhibit molar
nucleotide ratios which are identical. The major difference resulting from the addition of the
Y chromosome to the genome appears to be that of a 5-10% increase in the amount of DNA as
compared to the associated RNA. The simplest interpretation of the data is that heterochromatic
DNA such as that derived from the Y chromosome of Drosophila does not contain an associated
RNA.
MEYER, HELEN U., and H. J. MULLER, Indiana University, Bloomington, Ind.: Mortality in.
duced by X-irradiation of early Drosophila embryos of structurally different genotypes.-Earlier
work (LAMY and MULLER 1939; MULLER and PONTFZORVO 1939-1942), utilizing offspring of
triploid females, has shown that most mortality induced by X-irradiation of early embryos of
Drosophila is caused by some process other than chromosome loss. We have recently reinvestigated
this problem, by determining the influence of a second-chromosome deficiency (ugB) on
this mortality. These experiments parallel those previously carried out in our laboratory by
OSTERTAG (Thesis, 1961, and in press), and confirmed by ourselves on the influence of this deficiency
on the mortality induced by X-irradiation of third-instar larvae. 8001- were delivered to
embryos in the polar-cap stage (extending from blastoderm formation to beginning gastrulation).
The following rates of survival to the imaginal stage were obtained for the four genotypic
classes of 2536 irradiated individuals, as expressed in terms of the frequencies of survivors
after irradiation relative to (divided by) the frequencies of the same classes of imagoes obtained
from 1094 nonirradiated (control) embryos derived from the same crosses: structurally normal
females 48.4%, deficient females 55.5%, structurally normal males 62.4%, deficient males

ABSTRACTS 971
63.1%. These results differ markedly from those obtained by OSTERTAG and by ourselves from
irradiation of third-instar larvae, which show much lower mortality among females than males
and among nondeficient than deficient individuals. We conclude that irradiation kills these
early embryos, unlike later stages, by a different process, for the most part, than chromosome
loss. Our data show, moreover, that this mortality, unlike that induced by later irradiation, is
concentrated within a relatively short postirradiation period. (Supported by U. S. Public Health
Service contract RG-5286, C4.)
MILKMAN, R., Syracuse University, Syracuse, New York: Crossveinless polygenes in 40 wild
lines of Drosophila me1anogaster.-Each of 40 wild inseminated females collected in three Syracuse
locales was allowed to produce progeny. From each F, 1000 flies were examined for posterior
crossvein defects. Of the 40 lines, only four contained no crossveinless (cue) flies. Among
the rest, 28 contained between one and seven per 1000; five contained between 11 and 19; and
three contained between 46 and 63.-The six highest strains have been subjected to selection for
the crossveinless phenotype. A polygenic basis for the trait is indicated in each case, and progress
has been quite rapid. These results confirm and extend conclusions about the genetic basis
of the cue phenotype in nature: it appears to result from the rare combination of fairly common
genes. Whether these genes in a local population are common as a class or common as
individual alleles remains to be determined from crosses. Indications from crosses of cue strains
of diverse origins are that for the species as a whole there are many different alleles which
produce the cue trait in some teams and not in others.
MITTLER, SIDNEY, and G. N. SAMPSON, Northern Illinois University, DeKalb, Illinois: Distorted
sex ratio in offspring of attached-X females in D. me1anogaster.-The sex ratio of the
stock B lua sCS In SSI (Muller-5) yf: = is 1 yellow forked female to 1.18 Bar eye male, however
when the attached-X females are mated to Canton-S males the ratio of the offspring is 1 attached-X
female to 1.98 Canton-S male. The sex ratio of the F, of this cross is 1 to 2.77. The
excess of males from matings to attached-X females was also found in the offspring of matings
with Oregon-R males. The F, ratio is 1 to 1.52; F,, 1 to 1.49; F,, 2,904 males to 1,974 females or
1 to 1.47. The females are always attached-X and the males Oregon-R. At first it was believed
that the excess of males was due to the Y chromosomes of the Canton-S and Oregon-R in that
this chromosome did not stimulate the development of the attached-X egg. The Y chromosomes
that fertilize the attached-X egg in the F, and even numbered F generations are from the
original M8/yf: = stock and excess males are also found in these generations. The M-5 male
may not be as viable as the Oregon-R or Canton-S males and if the viability of the attached-X
female is also reduced or the production of these eggs is less, this can account for the excess of
males in matings to attached-X. There may be also some factor or factors on the other chromosomes
introduced by mating with Oregon-R or Canton-S that may inhibit the production of
attached females.
MOH, C. C., Inter-American Institute of Agricultural Sciences, Turrialba, Costa Rica: The
effects of p-dichlorobenzene pretreatment and temperatures on the chromosome morphology of
Phaseolus vulgaris.-In studying the cytology of Phaseolus species, attempts were made to find
a suitable cytological technique to facilitate chromosome counting and the morphology study.
A satisfactory and relatively simple technique was to pretreat the germinating seeds (two-day old
with a radicle 0.5 to 1.0 cm long) with a saturated aqueous solution of p-dichlorobenzene as
described by MEYER (Stain Technol. 20: 121-125, 1945) but using low temperatures. The pretreated
radicles were then excised, fixed in cold Carnoy's fluid (4°C) for two to three days, and
stained with a mixture of ten parts aceto-orcein plus one part 1N HC1 before the smear was
made.-Pretreatment at high temperatures (e.g. 25 "C) usually caused chromosome stickiness
and little chromosome scattering, and thus made the observation difficult. The best results were
obtained by pretreating the cytological material at 4°C for 6 to 24 hours depending upon the

9 72 ABSTRACTS
purpose of the study. For chromosome counting, a 12- to 24-hour pretreatment was excellent
since the contraction of the chromosomes reached a maximum and the countable mitotic figures
were abundant. For the morphological study, a six-hour to 12-hour pretreatment appeared to be
the best since this duration of pretreatment did not obscure the detailed structure of the chromo-
somes. The chromosome morphology of Phaseolus uulgaris (n = 11) is also described. (This
work was supported by the U.S. Atomic Energy Commission contract AT(30-1)-2043.)
MOHLER, J. D., Oregon State University, Corvallis, Oregon: Gene action in polygenic systems
of Drosophila.-Two polygenic crossveinlesslike (cul) lines selected from different wild-type
sources are being used for a study of accumulative gene action. The genetics of each line includes
a major gene, chromosome I11 in cul-5 and the X chromosome in cul-6, with penetrance modifiers
on the other chromosomes. Each line has been separated into high and low penetrance sublines.
The patterns of wing vein development are strikingly different for the two sources: a delay
of four hours characterizes the wing development of cul-5; apparently the interruption of the
crossvein occurs in a manner similar to that described for mutants such as cu. In cul-6 the earliest
steps in vein formation eliminate the normal crossvein; any crossvein appears secondarily. These
differences in origin, genetics and development suggest a possible identification of specificity of
action for the individual genes in the polygenic systems.-The measure of penetrance in combinations
of chromosomes X, I1 and I11 from the various lines and sublines permits a recognition of
the contribution each chromosome makes to the cul effect. In those combinations that have been
studied there is no indication of specificity of action at the phenotypic level. The rank of the
second chromosomes as penetrance modifiers is the same for any genetic combination containing
either of the two major genes. These latter in combination also show accumulative effects on
penetrance. Whether the modifying effects of a given chromosome depend upon the same loci in
each of the two systems is not inferable. (Supported by grants from the National Science Foundation
and the General Research Fund, Oregon State University.)
MOREE, RAY, Washington State University, Pullman, Wash.: Data on relatiue fecundity in-
uoluing the mutant ebony" of Drosophila melanagaster.-To test fecundity relations of the car-
riers of genotypes +/+, +/ell and e"/e", males and females of each genotype were crossed in
all nine possible combinations. Within each sex, the above genotypes were in the respective pro-
portions 1:2: 1. Each cross was made in a separate bottle with five flies of each sex per bottle; thus
there were ten sets of 16 bottles each. The total numbers of progeny produced by each genotype,
in the order given above, were for the female parents 37452, 83476, 30222, and for the male
parents, 35141, 78600, 374.09. Thus the fecundity coefficients are: for females, 0.897, 1.0, 0.724; for
males, 0.894, 1.0, 0.952; and combined, 0.896, 1.0, 0.835. The deviations from expectations are
highly significant and indicate, obviously, that the heterozygotes are heterotic and that there is
some selection against e"/e". The frequencies of progeny genotypes were 0.248, 0.518 and 0.234,
for the order of genotypes given above. The numbers of parents per bottle were such as to mini-
mize preadult inviability; nevertheless, some inviability occurred. Correction for this changed the
results only very slightly. Since the experiment does not distinguish between mating propensity
and fecundity proper, the above coefficients may be said to measure general, rather than specific,
fecundity. Together with information on relative viability, they help to explain the well-known
fact that e alleles are maintained at low frequencies for long periods in experimental populations.
(Supported by funds from the State of Washington Initiative Measure No. 171 for the support of
biological and medical research and by grant RG-4174 of the National Institutes of Health, U. S.
Public Health Service.)
MORPURGO,~ GIORGIO, (Introduced by R. C. VON BORSTEL), and FREDERICK J. DES.ERRES,
Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.: Factors influencing allelic
complementation among ad-3B mutants of Neurospora.-Studies on ad-3B mutants have shown
that complementation (the initiation of growth) begins after a lag that is variable from 18-24

ABSTRACTS 973
hours to several weeks, and that this lag is dependent on the particular pair of allelic mutants
combined. Furthermore, the rate of growth of these heterokaryons is also dependent upon the
particular combination of mutants and is not strictly correlated with the lag time. Various ex-
perimental conditions have been studied that have no effect on the individual mutants but which
alter either the time of heterokaryon formation or the subsequent rate of growth or both. For
instance, supplementation of the minimal medium with both 0.1 mg/liter adenine and 200
mg/liter casamino acids brings about a fourfold to fivefold reduction in the lag times found in
most heterokaryon tests with unsupplemented minimal medium. The effect of the D- and L-forms
of various amino acids has also been studied on 26 different combinations of ten complementing
ad-3B mutants. Whereas the effect of D-cysteine was aspecific and resulted in a pronounced re-
duction in the lag time of all combinations, the effect of other amino acids (inhibition or stimu-
lation) on the lag time and growth rate was heterokaryon-specific and not limited to the L-forms
alone. Almost all possible relationships between the D- and L-forms on the lag time and growth
rate have been found. The significance of these findings in the term of the mechanism of allelic
complementation will be discussed. It appears, however, that allelic complementation is a complex
phenomenon with at least two separate and independent phases. (1 Permanent address: Istituto
Superiore di Sanita, Rome, Italy.)
NAYLOR, ALFRED F., McGill University, Montreal, P.Q., Canada: A new rigorously-proven
theorem on mating systems.-All of several actually known or hypothetical mating systems of
the negative assortative type have either of two features: (1) a characteristic equilibrium allelic
frequency which is independent of initial frequency; or, (2) special conditions which make the
actual mechanism of the “system” dependent on the gene frequency which is to be maintained
while heterozygosity increases in the population. This remark is extended to a theorem, which,
while not momentous, is biologically novel in that it is an absolutely provable generality. An intuitive
interpretation will accompany the elementary proof.
NORBY, D. E., H. C. THULINE, and J. H. PRIEST, Rainier School, Buckley, Washington: X
chromosome differentiation in relation to coat patterns in cats.-Application of LYON’S hypothesis
of differential sex chromosome inactivation to the expression of the genes producing black and
yellow mosaic coat color in female cats depends upon establishment of their sex linked pattern of
inheritance. The demonstration of an extra chromosome in males with these colors overcomes
many of the past obstacles to the acceptance of such a pattern.-The expression of these alleles
appears to be influenced by the autosomal gene which controls the presence of white spotting.
In the presence of the spotting gene the colored patches are large; if its recessive allele (solid
color) is homozygous the patches are very small. Assuming that inactivation of one of the two
X chromosomes is responsible for the mosaicism, the size of the patch will be related either to the
time of inactivation during embryogenesis or to the specification ,of the chromosome inactivated
in the cells of a given patch. Thus, the postulated X chromosome inactivation would be under
autosomal control in one or the other of these two aspects.
NUFFER, M. G., University of Missouri, Columbia, MO.: Consideration of the suppressor ele-
ment hypothesis for mutable loci.-The generally accepted hypothesis for induction of muta-
bility at a particular locus by the two unit mutator systems found in corn is that an undefined
element moves to a gene site (A, for example) under the influence of a second element (Dt) and
while there suppresses the action of the gene so that it expresses a recessive phenotype (a). This
phenotype continues until the element moves away at which time normal gene function is re-
stored producing sectors of A like tissue, hence the designation p. In the absence of Dt, am is
completely stable but when after many generations the two factors are again placed in the
same cells reversions to A occur. If am is A with a separable element suppressing it one would
expect that the element may be dislodged or destroyed (in the absence of Dt) by chemical muta-
gens, UV or perhaps even with X rays. Such a dislodging without loss of A should produce a

9 74 ABSTRACTS
full A phenotype. Cultures of am dt treated with effective doses of X rays, UV, and ethyl meth-
anesulfonate have failed to produce a single case of reversion to A. If am is A plus a suppressor
element then one may expect occasional errors in replication such that one or both are not
reproduced. Loss of A or of A plus element should give a null phenotype that is difficult to detect
but loss of the element alone should give A tissue which can easily be seen. Observation of am
dt material which would permit 84 x lo6 chances for reversion failed to give a single case of
loss of the suppressor element. As a result of these observations an alternative hypothesis will
be considered.
OAKBERG, E. F., and EVELYN CLARK, Biology Division, Oak Ridge National Laboratory, Oak
Ridge, Tenn.: Species differences in radiation response of the mammalian primary oocyte.-A
dose of 50r destroys almost all of the early oocyte stages of the adult mouse. As a result, permanent
sterility occurs after the more mature, radioresistant oocytes have been ovulated. In contrast,
early oocytes of guinea pigs (GENTHER 1934) and monkeys (VAN ECK-VERMANDE 1959)
have been reported to have high radiation resistance, and fertility appears normal after exposures
of 300r in dogs (ANDERSEN and SCHULTZ 1960) and after several hundred roentgens in
women (PECK et al. 1944)). We have observed 30% survival of early oocyte stages in the guinea
pig after 200r, but only 0.3% survival of early oocytes in the mouse after 50r. A species
difference in the opposite direction occurs in that older follicles are destroyed by 200r in
the guinea pig, but survive 500r in the mouse.-In mammals, the definitive number of
oocytes is formed before birth; oocyte development then is arrested until growth of the follicles
occurs. In the mouse, this arrest occurs at the dictyate stage, but in the guinea pig, nuclear
cytology after Bouin’s fixation suggests an arrest in zygotene or early pachytene. Thus, species
differences in the meiotic prophase stage at which oocyte development is arrested could be an
important factor in radiation response. This hypothesis also is in agreement with the known
effect of meiotic prophase stages on radiation sensitivity within species.
OSBORNE, T. S., A. 0. LUNDEN, and M. J. CONSTANTIN, University of Tennessee-AEC Laboratory,
Oak Ridge, Tenn.: Influence of preirradiation humidity on sensitivity of dormant seeds to
gamma rays.-Recent studies have shown dormant seeds (embryos) to become more sensitive to
ionizing radiation when drier than normal. Barley seeds were said to have a plateau of high
radioresistance when equilibrated prior to irradiation at relative humidities (RH) of about 50
to 90%, but no such plateau was found for seeds of tomato or oat.-We have studied dry weight
of seedlings from seeds of eight botanical families, each preconditioned in our forced-air, glycerol-moderated
systems (Plant Physiol. 36:309-312, 1961) at RH from ten to 85%, then given
one of seven acute doses of Coo0 gamma rays from 0 to 372kr. Results permitted the following
inferences.-(I ) Of the eight families tested, only one (Gramineae: barley and fescue) showed
anything like a plateau of radiosensitivity with changing RH.-(2) Maximum radioresistance
occurred at a RH varying with taxon.-(3) RH for maximum radioresistance shifted upward
with increasing radiation dose, thus could not be accurately determined by one or a few doses.-
(4) RH conferring maximum radioresistance to dormant seeds was usually lower, and sometimes
much lower, than the 60 to 70% RH heretofore generally considered optimum.
OSTER, I. I., and GLORIA BALABAN, (Introduced by E. A. Carlson), The Institute for Cancer
Research, Philadelphia, Pennsylvania: Cytological demonstrations of induced breakage in somatic
chromosomes of Drosophila.-X-rayed and chemical mutagen-treated larvae of Drosophila
have been shown to exhibit an increase in preimaginal mortality and a decrease in the life-span
of the surviving adults. This phenomenon, essentially akin to the premature ageing observed in
irradiated mammals, has been shown by several genetic tests to be based on chromosomal loss
(OSTER 1959; MULLER and OSTERTAG 1959). One of these involved the use of males containing a
ring-shaped X-chromosome. Since ring chromosomes are more prone to loss following breakage
than normally-constituted chromosomes, males hemizygous for the former are more susceptible

ABSTRACTS 975
to mutagen-induced life-shortening.-Direct cytological observation of this damage would offer
additional confirmation for our interpretation based on the breeding results and a simple method
for testing other agents as possible mutagens.-By utilizing a combination of techniques recently
introduced by E. B. LEWIS (Drosophila Inform. Serv., 34) for demonstrating the mitotic
chromosomes of Drosophila larval ganglia and a lactic-acetic orcein-fast green stain developed
by RUDKIN and KAMRER (unpublished) we have been able to obtain preparations with 15-20
figures per ganglion in which the full complement of chromosomes can be clearly analyzed
(OSTER and BALABAN, Drosophila Inform. Serv., 37) .-Preliminary observations have yielded
results completely in agreement with the genetic tests, i.e., the relatively high susceptibility to
loss following irradiation of ring-shaped chromosomes as evidenced by their breakage and frequent
involvement in anaphase bridges. Such effects can also be observed following exposure to
relatively low doses of X rays.-Also this method has been successfully applied to the somatic
chromosomes of the housefly. (This work was supported by U. S. Atomic Energy Commission
Grant AT (30-1)-2618).
OSTER, I. I., EDNA POOLEY, and ROSE SCHWARZ, The Institute for Cancer Research, Philadelphia,
Pennsylvania: The frequency of mosaic mutations induced by gamma rays and neutrons.
-Following AUERBACH'S demonstration that mustard gas produces a relatively high frequency
of mosaic mutations in mature spermatozoa of Drosophila melanogaster (1945) several other
alkylating agents have been shown to behave similarly (in collaboration with E. CARLSON and L.
SNYDER). Since our understanding of the mechanisms(s) involved in chemical mutagenesis may
be broadened by comparisons with the spectrum induced by other types of agents, we have
treated homogeneous samples of mature spermatozoa (by using inseminated females) with
sparsely ionizing radiation (i.e., gamma rays from a Cobalt-60 source) and densely ionizing
radiation (i.e., fast neutrons) and analyzed the incidence and mode of expression of mutations induced
at the dumpy locus. We would like to thank DR. H. J. CURTIS and ROBERT WOODLEY for
arranging these irradiations for us at the Brookhaven National Laboratory.-A gamma ray
dose of 4000r (delivered at the rate of U)0,000r/hour) yielded 64 mutations at the dumpy locus
amongst 13,100 offspring (0.49%); 18 of these were mosaics (28%). A neutron dose of 750 rads
yielded 52 mutations at the dumpy locus amongst 22,960 offspring (0.23%); 16 of these were
mosaics (31%). These results resemble those obtained with X rays (CARLSON) but differ significantly
from the 80-90% incidence of mosaics following treatment with chemical mutagens.
Thus differences in LET do not result in different frequencies of induced mosaics, and unlike
chemicals, ionizing radiatifon tends more often than not to effect both DNA strands while traversing
the chromosome.-In addition, preliminary results with X-irradiated spermatocytes and
spermatids have indicated that although mosaics can be induced occasionally in these stages the
frequency of such mosaics is similar to that produced by irradiation of spermatozoa. (This work
was supported by the U. S. Atomic Energy Commission Grant AT (30-1)-2618.)
PALM,^ JOY, and M. R. IRWIN, University of Wisconsin, Madison, Wisconsin: Interaction of
nonallelic genes on c,dlular antigens in species hybrids of doves (Columbidae) .-Among the
backcross hybrids resulting from matings to Streptopelia risoria of the species hybrids and selected
backcross hybrids obtained by respective matings of chinensis, humilis, orientalis and senegalen-
sis to risoria, one related group of cellular antigens (group4, called ch-4, hu-4, or4 and se-l)
has been demonstrated. Three antigenic factors (a b c) have been assigned to the ch-4 character
in chinensis. Fractionation of antisera against the cells of the backcross hybrids crarying ch-4
revealed three additional antigenic factors (d e f ) not present in either parental species. How-
ever, these three factors are present as normal constituents of the cells of all individuals carrying
the group-4 antigen in humilis, orientalis and awegalensis.-Furthermore, backcross hybrids
carrying ch-4, hu-4, or4 or se4 also possessed additional factors (g h) of a hybrid substance
and one or the other, or both, of these, are carried normally on the cells of certain other species
of Co1umbidae.-All birds from inter se matings of backcross hybrids with any group4 char-
acter possessed the five antigenic factors (d e f g h) of the hybrid substance if they also carried

9 76 ABSTRACTS
the group-4 antigen. It appears that both homozygotes and heterozygotes carried the hybrid
substance, and that it was an interaction product of genes on nonhomolomgous chromosomes
(1 Present address: The Wistar Institute, 36th Street & Spruce, Philadelphia, Pennsylvania.)
PETERSON, PETER A., Iowa State University, Ames, Iowa.: The many forms of the components
of a mutable system in maize.-Mutable genes in maize (in this case a,, colorless, to A,, color),
showing varied rates of mutation, are under the influence of specific identifiable components. The
components of this mutable system include two element+Z, that controls the action of the gene
in question when intimately associated with it and En that controls the action of I by removing
or inactivating I. Both of these components have distinct and varied forms and are recognized by
the diverse patterns that they effect. Patterns of mutability are determined by the time (manifest
in size of mutant area) and frequency (manifest in number of mutant areas) of mutation events.
-The individuality of the distinct I types is demonstrated by the expression and maintenance of
specific pattern types. The range in pattern expression is from a very early mutation to a very
late change which is expressed by small-sized dots at the crown of the kernel. The individuality
of the distinct pattern expression is maintained until a mutation event occurs that results in a
changed expression. This same range of patterns expressed as a function of rate and timing of the
mutation events is also observed with the En factor. This is determined by testing a number of
En derivatives against a common I form which results in a wide range of pattern expressions.
In addition, somatic changes of one pattern type to another are frequently observed.-These results
indicate that both I and En have a wide range of forms and may readily change from one
to another. The final pattern is dependent on the particular En as well as the particular I and/or
the interactions between them. This is unlike the mutable pericarp locus where pattern differences
result from the varied number of tr-Mp present. Evidence thus far suggests that these
differences in the components represent a change in composition as opposed to a change in position
resulting from transposition.
PETRAS, M. L., and T. A. CHURCH, The University of Michigan, Ann Arbor, Michigan: The
inheritance of a serum esterase component in Mus musculus.-Zone electrophoretic studies with
starch gel as the supporting medium have revealed the presence of at least nine serum esterase
bands with the substrate a-naphthyl butyrate in the house mouse (HUNTER and STRACHAN, Ann.
N. Y. Acad. Sci. 94:861, 1961). A preliminary survey of a number of inbred strains showed that
the only interstrain differences appear as variation in intensity of some of the bands. In a pregnant
female obtained from a feral population a more obvious difference was observed. The
zymogram showed the absence of the fastest migrating (anodal) band, or “band one,” of HUNTER
and STRACKAN. The four offspring of this female included one animal with no first band and
three with a light first band. To determine whether or not this variation had a clear-cut genetic
basis a number of crosses were made. Classification of 113 offspring from 23 sibships, representing
five of the six possible types of matings revealed the presence of three phenotypes: no first band,
light first band and dark first band. The results of these matings are in agreement with the
hypothesis that the first esterase band in Mus musculus is inherited as if controlled by a pair of
autosomal alleles. (Supported in part by USPHS Genetics Traineeship 2G71C3, and USPHS
Research Grants C4305 and c5559.)
PIPKIN,
S. B., The Gorgas Memorial Laboratory, Panama, R. de P.: A monogenic polymor-
phism in Drosophila lebanonensis 1ebanonensis.-A monogenic mesonotum color trimorphism in
D. 1. lebanonensis was shifted to dimorphism and in the direction of monomorphism in laboratory
cage populations initially composed of homozygous dark (ss) and homozygous light (SS) strains
derived from originally trimorphic populations. SS homozygotes eventually had the highest
selective value in all cage populations except in a single population where approximately equal
selective values of SS hsomozygotes and Ss heterozygotes were opposed. The ss dark homozygotes
had the lowest selective value. Recombinational changes in selective values of SS and Ss during

ABSTRACTS 977
the course of the experiment were suggested. The trimorphism was prolonged in cage populations
begun with 80% ss (homozygous dark) and 20% SS (homozygous light) parents compared with
populations begun with equal numbers of SS and ss individuals, showing dependence upon the
frequencies of these genotypes in initial populations. The shift towards monomorphism was
strongest in cage populations begun with Ss parents, hybrids of a single homozygous light and a
single homozygous dark strain. The effect of strain heterosis on early generations of certain cage
populations was to prolong the period of trimorphism.-Modifiers both in the light and dark direc-
tion caused errors in scoring SS, Ss, and ss phenotypes so as to make necessary individual male
testing of samples of cage populations. These modifiers could be considered homeostatic since
they caused less drastic phenotypic changes compared with genotypic changes in certain popula-
tions. (Supported by Research Grant 6813, from the Division of General Medical Sciences,
Public Health Service, Bethesda 14, Md.)
PRENSKY, WOLF, Biology Department, Brookhaven National Laboratory, Upton, New York:
Uptake of thymine-methy6Ht by pachytene chromosomes of Lilium longiflorum-Anthers of
Lilium longiflorum were treated with tritiated compounds (thymidine-H3, thymine-HS, uridine-
H3, adenosine-Hs and leucine-H3) in various stages of prophase I. The isotopes were administered
by injection into buds, through cut ends of stems, agar blocks placed on cut ends of anthers
and agar culture of excised anthers. Anthers were fixed when they were expected to be in anaphase
11. All methods, except for injection into buds, most frequently resulted in the death of
the anthers Hefore the second meiotic division. For injected buds, treatment with 5 pc of thyminemethyl-Ha
(100 pc/ml, S.A. 1.0 C/mM) resulted in positive autoradiographs of second division
chromosomes. The isotope was applied during mid-pachytene (bud 19.9 mm long), and grains
were observed over limited areas of MI1 and AI1 chromosomes. Since DNA synthesis in pollen
mother cells has been shown, by autoradiographic as well as enzymatic studies, to occur mainly
in preleptotene, the distribution of grains in chromosomes labeled during pachytene suggests
the occurrence of DNA synthesis as a result of crossing-over.-Because of the extensive mortality
of treated material, and the uncertainty with respect to successful administration of tritiated
compounds to surviving pollen mother cells, negative autoradiographs preclude the interpretation
that the other compounds used cannot be incorporated. (Research carried out at
Brookhaven National Laboratory under the auspices of the U. S. Atomic Energy Commission.)
RAI, K. S., University of Notre Dame, Notre Dame, Ind.: X-ray-induced mitotic changes and
mortality in Aedes aegypti Linn.-Cytogenetic effects of X rays (500,l000,2000,4000r) on the
NIH strain of Aedes aegypti Linn. were studied. Larvae were reared under controlled conditions
and were irradiated six days after hatching at a time when most were in the early fourth instar.
Five to ten larvae were fixed at intervals of 0, l%, 6, 12, 18, 36 and 72 hours after irradiation.
Mitotic chromosomes were studied from squash preparations of larval brains stained with aceto-
lactic orcein. Mitotic activity was measured in terms of the total number of dividing cells per
brain.-Initially X rays inhibited cell division. Mitotic activity was almost completely sup-
pressed 1% hours after irradiation. After a time (depending on dose used), this effect was re-
placed by a great increase in mitotic activity. Twelve hours after irradiation, the larvae ex-
posed to 500 and 1000r showed about twice as many mitotic figures as did the unirradiated ma-
terial. The increase in mitotic activity at higher doses was less extreme and took longer to
occur.-Most of the cell divisions were aberrant. Among the chromosomal aberrations noted
were deletions, exchanges, rings, dicentrics and anaphase bridges. Very few chromatid aberra-
tions were observed.-A relationship existed between the dose received and the developmental
stage at which an individual died. The higher the dose, the earlier the death occurred. Further-
more 2000r or more resulted in almost complete mortality.-Adults from larvae receiving 500r
were normal with respect to number of eggs laid, percentage of egg hatch and subsequent devel-
opment of offsprings. (Supported in part by Atomic Energy Commission Research Contract AT
(11-1)-38 and NIH Grant No. E-2753.)

978 ABSTRACTS
RASMLJSSON, D. C., L. H. SMITH, and W. M. MYERS, University of Minnesota, St. Paul, Minn.:
Effect of genotype on accumulation of strontium in three plant species.-Large genotypic differences
for Srs9 accumulation have been found within species. Fifty genotypes of wheat and
soybeans and 48 of barley were studied to determine the degree of genotypic control of Sr89 accumulation
in the grain. The plants were grown in the greenhouse in pots containing soil to
which strontium was added prior to planting. Srs9 was applied with and without stable strontium.
The rate of application of Sr89 was 25 pc per pot and for stable strontium, Sr(NO,),, .5
m.e./100 g of soil. Soybeans accumulated about three times as much Sr*Q as barley and wheat.
The largest amount of intraspecific variation was found in wheats; certain genotypes accumulated
4.3 times as much as others. For barley and soybeans the ratio of highest to lowest accumulation
was 3.2 and 3.5, respectively. In different experiments the relative rank of genotypes for
Srs9 accumulation has been in good agreement. These results indicate that genetic differences
within species have an important influence on strontium accumulation.
RAUCH, HAROLD, University of Massachusetts, Amherst, Mass.: Effect of the D locus on phenylalanine-tyrosine
metabolism in mice.-In adults carrying recessive alleles d (dilute) or dl
(dilute-lethal) COLEMAN found decreased conversion of phenylalanine to tyrosine via inhibition
of the enzyme phenylalanine hydroxylase (Arch. Biochem. Biophys. 91 :300, 1960). Are other
enzymes involved in phenylalanine-tyrosine metabolism affected and what are their patterns of
development?-For various D genotypes phenylalanine hydroxylase, phenylalanine-pyruvate
transaminase and tyrosine-a-ketoglutarate transaminase activities were assayed from birth to
ten weeks of age. Pronounced differences develop during the second to fourth weeks and persist,
though less markedly, into adulthood. For hydroxylase, maximum inhibition occurs during the
third week such that dl/dl has least activity, d/d more and D/D most; heterozygotes are intermediate.
For phenylalanine transaminase, peak activity occurs at 14 days, D/D showing twice
that of dl/dl with d/d intermediate. For tyrosine transaminase, maximum activity appears at
2l-U days, D/D having one third that of dl/dl with d/d intermediate. Transaminase differences
are considerably less in adults.-The D-locus influences phenylalaninetyrosine metabolism, most
obviously during the early weeks following birth. That recessives can neither hydroxylate nor
transaminate phenylalanine so well as dominants, suggests excess circulating phenylalanine
while decreased hydroxylation plus increased tyrosine transamination suggests the possibility of
reduced available tyrosine. A possible causal relationship to neurological affects of this locus is
now being investigated. (Supported by U. S. Public Health Service Grant RG-5921.)
REDDY, G. M., and E. H. COE, University of Missouri and U.S. Department of Agriculture,
Columbia, MO.: Extension of the gene-action sequence in anthocyanin synthesis in maize by
some special tests.-The gene-action sequence for C,, R, A,, and A, in anthocyanin synthesis,
reported previously, was constructed through intertissue complementation between aleurone tis-
sues of singly-recessive testers. The position of bronze mutants in the sequence was inconclusive
and requires a special test, using double-recessive types.-Distinguishable pieces of fresh
“active” (20-25 day old) aleurone tissue of colorless double recessive bz, bz, were paired, in the
fashion described previously, with colorless a,, and colorless r bz, and r bz, were paired with
faintly pigmented bz, and bz, testers in the four possible combinations. The 0, tissue develops
pigment in az:bz,bz, pairs, indicating that A, action definitely precedes that of Bz, and Bz,. The
r bz, tissue develops pigment in r bz,:bz, pairs, indicating that R and Bz, precede Bz, in the
sequence. The r bz, and r bz, tissues remain colorless in the other pairs, however, showing that
there is no diffusion of pigment itself from brronze tissues into a pair mate. The sequence of action
thus can be extended as follows: (Cr), C,, R, (In), A,, A,, Bz,, Bz,. Parentheses indicate doubt
based on the possible lack of straight forward relation of C’ and In to the sequence.--These studies
with double recessive mutants, in general, can be extended in the placement of other modifier
genes, such as pr and in, in the sequential order of gene action in anthocyanin synthesis.

ABSTRACTS 9 79
RBDEI, G. P., University of Missouri, Columbia, MO.: Genetic block of “uitamin thiazole” synthesis
in Arabidopsis.-An X-ray-induced recessive mutation (tz) interferes with the synthesis
of the thiazole moiety of vitamin B,. The mutants germinate but die befare the appearance
of rosette leaves unless 4-methyl-5-P-hydroxyethylthiazole (TZ) is supplied in an aseptic agar
medium or into the soil. A supplement of 0.1 microgram TZ per five ml medium restores full
viability and normal growth. The paucity of TZ involves a special chlorophyll defect characteristic
for thiamin (TH) deficiency. TH substitutes well for TZ. The pyrimidine moiety of TH,
2,5-dimethyl-4-aminopyrimidine (PY) is completely inactive however. The antimetabolite oxythiamine
(4-NH2 group of PY is replaced by OH), which contains an appropriate TZ, also satisfies
the requirement though in an amount about a hundred times larger.-Another of our Arabidopsis
mutants (py) is blocked in PY synthesis (Genetics 45:1007), while LANGRIDGE reported
(Australian J. Biol. Sci. 11 : 58) a third which is involved in the coupling of PY to TZ and consequently
responds to added TH only. Thus the completeness of information about the genetic
control of vitamin B, synthesis in the higher plant Arabidopsis compares favorably with that of
Neurospora.
REMINGTON, CHARLES L., Yale University, New Haven, Conn.: Genetics of mimetic characters
in the genus Limenitis (Lepidoptera).-The butterfly genus Limenitis in North America includes
five closely related but phenotypically unlike species. Two (L. archippus and L. astyanaz) are
mimics of unrelated distasteful butterflies, and a third (L. lorquini) probably is also mimetic
in color and pattern. L. archippus has three distinctive races, each resembling a different model
species or race. The other two species resemble Old World relatives and probably have the color
and pattern formerly possessed by the presently mimetic species. By the technique d hand-pairing,
several of the possible F, hybrids and backcrosses have been made. The conspicuous mimetic
color characters prove to be under simple Mendelian control. An objection to the mimicry hypothesis
is based on the presumption that numerous small hereditary changes would have been
required in the evolution of the mimic, with the intermediate stages therefore having been nonmimetic
and not favored by selection. This does not apply in the case of Limenitis; in each
mimic a single genetic change produces a color form reasonably similar to the model, and one
additional change makes the mimetic resemblance extremely close.
RICHTER, A., Wistar Institute, Philadelphia, Pa.: Stages in the maturation of equine encepha-
litis virus.-These studies were undertaken in part as a prerequisite to the isolation of mutants
unable to complete maturation.-Equine encephalitis virus consists of a ribonucleoprotein core
and a lipoprotein outer coat. This outer coat renders the viral RNA nonextractable by cold
phenol and resistant to the action of ribonuclease. Upon removal of the coat by treatment with
deoxycholate, the viral RNA may be extracted in infectious form by mild salt treatment as well
as by cold phenol.-From the postmitochondrial fraction of chick embryo fibroblasts infected
with Western equine encephalitis (WEE) virus, a component can be isolated which contains
the viral RNA in a form extractable by cold phenol and susceptible to ribonuclease. After detach-
ment from cytoplasmic membranes by deoxycholate treatment, this component resembles the
virus core in all known properties including rate of sedimentation in the ultracentrifuge. The
most likely interpretation of these results is that the component found in infected cells repre-
sents the immediate precursor of the mature virus and is identical to the core. The biosynthesis
of the WEE core may thus be compared to the biosynthesis of the complete virus particle of
simple ribonucleoprotein viruses such as polio.
RICK, C. M., and G. S. KHUSH, University of California, Davis, Calif.: Preferential pairing in
tetraploid tomato smcies hybrids.-Seed fertility of 4N F, Lycopersicon esculentum x Solanum
pennellii is nearly normal and higher than that of the corresponding 2N hybrids. The mean
number of multivalents (mostly IV) per PMC varies from 3 to 3.5; whereas it ranges from 5 to
5.5 for the highly sterile autotetraploid L. esculentum. Chromosomes of the parental species

980 ABSTRACTS
pair regularly in meiosis of the 2N hybrids, and four of the I2 bivalents are consistently hetero-
morphic, the differences reflecting the size of chromatic zones flanking the centromeres. The
proportion of heteromorphic bivalents in the 4N hybrid meiosis can thereby provide an estimate
of the extent of allosyndesis. In samples of PMC from two such hybrids, 6.6% of the bivalents
were heteromorphic. Assuming random multivalent formation and a variable level of chromatid
association, the yield of recessive gametes in duplex hybrids is estimated at 9.4% to 13.0%.-A
genetic analysis of pairing associations can be made by testing segregation of 4N hybrids hetero-
zygous for recessive markers derived from the esculentum parent. Testcross matings of the type
a a a a x a a + + yielded from 7.4% to 15.4% (x= 10.5) multiple recessives for six markers
on four different chromosomes, corresponding to the segregation expected on cytological grounds.
The relatively low level of preferential pairing confirms the early findings of a close genetic
relationship between L. esculentum and S. pennellii. The polyploid hybrids of these species are
of more than ordinary interest for their remarkably high fertility in spite of a high level of allo-
syndesis. (This research was supported in part by grant G-10704 of the National Science Foun-
dation.)
ROBERTS, PAUL, University of Chicago, Ill.: Interchromosomal effects, crossing-over and non-
disjunction in Drosophila.-Simultaneous measurements of X chromosome crossing-over and
nondisjunction were made with combinations of ten different heterozygous X inversions and the
Curly and Payne autosomal inversions. The percentage of X nondisjunction of the different
inversions showed a statistically significant linear regression on percentage of noncrossover
tetrads. Increases in crossing-over were observed with either or both autosomal inversions present
but X nondisjunction rarely occurred with both Curly and Payne present. This is further evi-
dence that the increase in crossing-over with heterologous inversions in the genome is real and
not merely an artifact from elimination of noncrossovers involved in nonhomologous pairing.
The latter, however, also plays a minor role under certain circumstances but occurs at a different
point in meiosis.-If the older theory that chromosomes pair, cross over and disjoin is correct, a
high rate of nonhomologous pairing between the X and an autosome should decrease crossing-over
between the X’s. Though progeny-tested exceptional females carried only noncrossover X’s and
the percentage of nonhomologous pairing in inversion-translocation bearing females was almost
50%, total crossing-over was essentially the same as in controls.-It is concluded that there are
two interchromosomal effects: the primary one operating at the time of crossing-over when only
homologues are paired. Subsequently, in the second effect, only noncrossover chromosomes are
sufficiently affected by less specific attractive forces that they pair nonhomologously, thus dis-
joining anomalously as proposed by GRFLL (1962).
ROBERTSON,
D. S., Iowa State University, Ames, Iowa: Suppressor and allele studies bearing on
the nature of the white-albino loci of maize.-Twelve different loci of maize have been studied
where mutations have resulted in carotenoid deficiencies in both the endosperm and seedling.
All of these mutants have white or pale yellow endosperms and the seedlings of those with little
or no measurable amounts of colored carotenoids are also devoid of chlorophyll when grown in
the light and are, therefore, albino.-Suppressor studies involving the cl, locus have demon-
strated that the mutant phenotype of the seedling can be suppressed either partially or completely
by independent modifying genes that do not affect the phenotype of the endosperm. Allele studies
at the w3, upg and y, loci have demonstrated for these mutants alleles that have phenotypes
corresponding to those produced by suppressors at the cl, locus. These studies demonstrate that
in some white-albino mutants, the phenotype of the seedling can be altered independently of the
phenotype of the endosperm through the action of suppressors or by mutation.-The significance
of these observations with respect to the structure and function of these genes is not clear. At the
present time, the results can be explained at the level of gene structure by assuming a bipartite
locus consisting of an endosperm and seedling component that can be affected independently by
mutations and/or suppressors or at the level of gene action by assuming functional differences

ABSTRACTS 981
of the mutant alleles depending upon whether they are present in endosperm or seedling tissue.
(This work was supported in part by grant G19395 from The National Science Foundation.)
ROMAN, H., J. FRIIS, and N. R. EATON, University of Washington, Seattle, Washington: The
effect of monochromatic ultraviolet radiation on ncciprocal and nonreciprocal recombination in
yeast.-The wavelengths 248, 265, 280, and 313 mp have been used to treat a diploid yeast culture
in which reciprocal and nonreciprocal recombination can be detected simultaneously. The
diploid culture is heterozygous at an adenine locus and heteroallelic at an isoleucine locus. Reciprocal
recombination occurring between the centromere and the adenine locus leads to sectored
red-white colonies; nonreciprocal recombination at the isoleucine locus results in reversion to
isoleucine independence. The shorter wavelengths are each effective in enhancing the frequency
of both types of recombination to a comparable degree; A313 is ineffective. The present evidence
therefore does not enable us to separate reciprocal recombination from nonreciprocal recombination
spectrally.
RUDKIN, G. T., DAVID A. HUNGERFORD, and PETER C. NOWELL, The Institute for Cancer Research,
Philadelphia, and Department of Pathology, School of Medicine, University of Pennsylvania,
Philadelphia, Pa.: DNA measurements of chromosomes, including zhe Philadelphial
chromosome, in human chronic granulocytic leukemia.-Human chronic granulocytic leukemia
(CGL) is characterized by a deficiency within one chromosome of group 21-22, probably number
21 (J. Natl. Cancer Inst. 27:1013, 1961). The present work is aimed at: (1) distinguishing
between deletion and translocation in this abnormal karyotype, (2) the detection of possible
differences in DNA content of the deficient chromosome (the Philadelphia1 chromosome, symbol
Phl) in different cases of CGL, and (3) measuring the distribution of DNA within the human
karyotype. Leukocytes from peripheral blood were prepared by the method of MOORHEAD, et al.
(Exptl. Cell Research 20:613, 1960) on quartz slides. Following digestion of the preparations
with ribonuclease, total absorbence (A,) of chromosomes at 257 mp was measured by the photographic
method of CASPERSSON and SCHULTZ. Measurements have been made on one tetraploid
nucleus (having two Phl chromosomes). Preliminary results show that Phl (AT=0.093) is
deficient for 4.0 percent of the DNA in a group 21-29 chromosome (AT = 0.154). Were the deficient
portion of the original (normal) chromosome not lost from the nucleus, but translocated to
another chromosome, it should be detectable by the methods employed. Since the largest chromosome
in the complement (number 1) had an A, of 0.68, the translocated piece (A, = 0.06)
would add ten percent or more to any chromosome in the complement. Considering chromosome
arms separately, the minimum increase due to the translocated segment would be of the order of
15 to 20%. Since the error of the method is less than ten percent, we expect to be able to distinguish
between the alternatives of translocation and deletion in the CGL karyotype.
RUSSELL, LIANE BRAUCH, JEAN W. BANGHAM, and CLYDE L. SAYLORS, Biology Division, Oak
Ridge National Laboratory, Oak Ridge, Term.: Delimitation of chromosomal regions involved in
V-type position effects from X autosome translocations in the mouse.-Two new cases of V-type
position effect., both involving the c locus, have been discovered. In preliminary tests, they behave
in an analogous fashion to the three reported by us earlier, and they are therefore assumed to
result from X autosome translocations. One was derived from irradiation of spermatozoa; the
other was spontaneous.-Further tests with the three position effects reported earlier have shown
that the autosomal regions affected are limited. Translocation T(X;8), which produces b variegation,
has no effect on m+. The order is tentatively assumed to be: break pokt--(7?)-W'-
(6)-&(7)-m. It is doubtful whether variegation of wi (whirler) would be detectable and
none has been found to date. Translocation T(X;l)c, originally detected by c variegation,
also variegates p+. However, while the c regions usually occupy more than half the fur, p regions
are SO small and scattered as to be almost imperceptible. The order is assumed to be: break point-
(

982 ABSTRACTS
(3?)-break point-(2?)-tp-(9)-p. Both p+ and tp+ variegate; however c+ does not. Since,
on the basis of four other independent cases c+ is known to be capable of variegation, it is con-
cluded that not all regions of the X chromosome can cause position effects in neighboring auto-
somal loci.-The results presented, and particularly the last one, argue against the hypothesis
that mammalian V-type position effects result from the circumstance that X-translocated auto-
somes share the inactivity of one X.
SAGER, RUTH, Columbia University, New York, N.Y.: A nonmapable unit factor in Chlamydomonas.-Wild-type
strains of Chlamydomonas reinhardi synthesize chlorophyll when grown in
the dark as well as in the light; a class of yellow mutants, yl-, like higher plants, make protochlorophyll
in the dark but require light for chlorophyll formation. In crosses of such yellow
mutants of spontaneous origin with wild type, only 2:2 segregations of green/yellow are observed
in tetrad analysis. These segregations occur only at the first meiotic division; therefore, if
chromosomal, y1 must be on or near a centromere. Crosses have been made between yI and each
of 11 centromere-linked markers (obtained from W. T. EBERSOLD), representing 11 linkage
groups of which six are one-armed (EBFXSOLD, et al., in press). No linkage whatever has been
found between y1 and any of the 11 tested markers. Evidence that these markers represent the
full chromosome complement comes from cytological studies of Feulgen-stained metaphase
chromosomes from colcemide-treated cells. Numerous figures were seen with eight chromosomes,
as well as many with 16 and intermediate numbers, resulting presumably from the action of the
drug. These results, confirm published reports by others of eight as the haploid number, and
suggest that with further analysis the 11 linkage groups will reduce to eight. On this basis, yI
is nonchromosomal, although segregating as a unit factor. Since there is but one chloroplast per
cell in this species, the chloroplast may be the carrier of this determinant; any other unit
organelle segregating regularly at meiosis may equally well be considered. Further evidence that
y1 is nonchromosomal derives from its susceptibility to the mutagenic action of streptomycin
(SAGER and TSUBO, Arch. Mikrobiol. 42:159, 1962). (Supported by the Public Health Service
and National Science Foundation).
SAND, SEAWARD A., Connecticut Agricultural Experiment Station, New Haven, Conn.: A
model for the cytogenetic partitioning of quantitatiue genetic expression.-Work previously summarized
(Genetics 46: 865, 1961 ) has been extended employing alien-chromosome-addition
plants derived from the interspecific hybrid of Nicotiana Zongiflora by N. Sanderae.-The genetic
system here open to study comprises the haploid complement of nine chromosomes (S) of
Sanderae added to the diploid background of ten pairs of chromosomes (LL) of longiflora. The
genetic expression of LLS, in comparison with LL control, can be accessed in terms of numerous
quantitative characters. Those initially chosen for study are specific dimensions of the floral
organs.-Successive backcrosses of LLS to LL have permitted isolation of a series of distinct
plant offtypes, which may include the nine single Sanderae chromosome additions (LL + Is).
Preliminary cytological, genetic, and biometric studies have been initiated using these off types.
-As a working hypothesis, the phenotypic expression of LLS is viewed as composed of six
major parts: (1) a component (N) proportional to chromosome number, (2) a pooled component
due to LL, (3) relatively autonomous expressions of each of the nine Sanderae chromosomes
(Is,-Iss), (4) interactions between the LL complement and each of the Sanderae chromosomes
(as LL X Isl), (5) interactions by pairs among the nine Sanderae chromosomes (as Isl x I,,!,
and (6) a residuum of higher-order interactions.-This theoretical model is employed in experimental
analysis of the plant material. The rationale for estimation has been considered in detail.
-The work possibly promises a contribution to knowledge about the topography of the genome,
with respect to the location of genes affecting quantitative characters.
SCHWARTZ,
DREW, Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.:
Analysis of mutations in the reguzatory system which alter the timing of gene action in esterase

ABSTRACTS 983
enzyme synthesis.-Five alleles of the E gene, E", EL, EN, ER, and ES, specify five electropho-
retically distinguishable forms of the pH 7.5 esterase enzyme in maize and teosinte. This en-
zyme is found in the developing endosperm as well as in the developing embryo, seedling and
plant tissue. Two new mutants designated E"' and Est are indistinguishable from EF and E" in
their behavior in the diploid tissue, but in the endosperm are characterized by a precocious sus-
pension of gene action. The activity of EF' is cut off earlier than ES'. In heterozygotes with a nor-
mal-acting allele, as for example EF'/EF'/EN, both alleles are equally active in the young endo-
sperm (14 days after pollination) and three enzyme bands are observed in zone electrophoresis,
intense FF and FN hybrid, and a weak NN. By 20 days after pollination the EF' allele is com-
pletely inactive while the EN allele still shows full activity and only a single esterase type, NN,
is present in the endosperm. These regulatory mutants involve alterations at or close to the site of
the structural gene since no recombinations have been found in more than 2500 endosperms
tested.
SEARS, E. R., U. S. Department of Agriculture and University of Missouri, Columbia, MO.:
The use of telocentric chromosomes in linkage mapping.-Telocentric chromosomes, which are
readily obtainable in common wheat through misdivision of monosomes, not only permit the assignment
of genes to particular chromosome arms but also make possible the determination of
gene-centromere distances. For example, the long arm of chromosome 6B carries the awn inhibitor
B,. To determine the distance of B, from the centromere, a telocentric carrying B, was
combined with a normal chromosome carrying b,. When the plants concerned were used as
males in a testcross, only six of 231 offspring had B,. Two of these six possessed the paternal
telocentric and were thus noncrossovers, and three had both paternal chromosomes and therefore
could not be scored. Thus crossing-over between B, and the centromere was only 1/228 or
O.M%. In the same experiment another gene on this arm, Sr,, (stem-rust resistance from the
variety Timstein), showed M.3 2 3.2% recombination with the centromere. In a second experiment
presence of a marker on the short (nucleolar) arm of the normal 6B allowed use of the
heterozygote as the female, and presence of a gene a few units proximal to Sr,, permitted
detection of some of the double crossovers. Here crossing-over between Sr,, and the centromere
was 49/98 or 50%. The gene proximal to Sr,,, pollen-killer (Ki), showed 9.2 *2.9% recombination
with Sr,,. In this and a third experiment not involving Sr,,, recombination between
Ki and the centromere was 43.1% 2 3,5%.-Neatby's virescent (U) on chromosome 3B showed
only 0.29% recombination with the centromere in 350 gametes tested.
SEECOF, R. L., Calif. Institute of Technology, Pasadena, Calif.: Treatment of eggs from carbon
dioxide sensitive Drosophila with X-rays and ultrauiolet radiation.-Eggs were collected from
females of a stabilized, carbon dioxide sensitive strain of Drosophila melanogaster, irradiated with
X-rays or ultraviolet light, and permitted to develop into adult flies. The titer of the virus-like
factor (sigma factor) causing the sensitivity was measured in these adults and compared to the
titer in adults that developed from untreated eggs. Ultraviolet radiation from a germicidal lamp
in doses of 2.00-600 ergs/mm2 (mortality 154%) caused 4-8-fold increases in titer. Higher
doses were not effective in raising titers. X-ray treatments in a range giving u)-70% mortality
failed to cause measurable changes in titer. The titer increases following ultraviolet light treatment
were significant in all of the three experiments done to date, but more elaborate control
experiments are needed to establish the effect. Experiments are now being done to confirm the
titer increases and to determine whether the titer increases represent an induction of infectious
sigma from a noninfectious stage in the sigma life cycle.
SHAMA RAO, H. K., and E. R. SEARS, Atomic Energy Estab., Trombay, India, and U.S. Department
of Agriculture, Columbia, MO.: EMS-induced mutations in hexaploid wheat.-Seeds of
normal Chinese Spring wheat and of monosomics 2B and 6B of this variety at 12% moisture
were soaked in 0.05 M ethyl methanesulfonate at 30°C for six hours, a treatment which permitted

984 ABSTRACTS
88% to 97% survival. Various types of sectors with chlorophyll deficiency, necrosis, and abnormal
growth were observed in the first generation of treated normals as well as monosomics. In ad-
dition, plants sectorial for nonsquarehead, subcompactoid, compactoid, and compactum-type
spikes occurred in MI. Most affected plants were meiotically normal, but others, and certain
phenotypically normal plants as well, had translocations, heteromorphic bivalents, and univalents.
-Although M, plants are still in the seedling stage, out of 117 plant progenies ten include me
or more chlorophyll defectives, five others include dwarfs of various distinctive types, and one
other progeny is segregating plants with necrosis between the veins of the leaves. The progenies
range in size from one to 31. Since ionizing radiations result in virtually no mutations of these
kinds, and since no such phenotypes are exhibited by nullisomics or tetrasomics for any of the 21
chromosomes of wheat, it appears that these EMS-induced mutations are not mere deficiencies
or duplications. This accords with results from experiments with microorganisms and biochemical
studies which indicate that EMS can cause gene changes through alkylation of the guanine
component of DNA. (This investigation is being carried out at the University of Missouri while
the senior author is an Exchange Visitor under the AID Program.)
SHAVER, DONALD L., Biology Department, Brookhaven National Laboratory, Upton, New
York: The effect of structural heterozygosity on the degree of preferential segregation in allotetraploids
of 2ea.-By mating appropriate stocks of 411 maize with 4n perennial teosinte, two
types of allotetraploids were produced, one carrying inversion 3a as a structually heterozygous
region, and the other without structural heterozygosity. The effects of the defined chromosome
rearrangement on preferential segregation was measured from testcross ratios of two genetic
markers contained in the inversion loop. In the structurally heterozygous allotetraploid, the
average segregation ratio for the contained markers is 25:1, compared to 10.3:l in the control
allotetraploid. The near absence of crossing-over and bridge formation indicates that structural
heterozygosity effectively eliminates interspecific gene flow in this region. It is concluded that
structural heterozygosity could be of major importance in the diploidization of new tetraploids in
nature (Research carried out at Brookhaven National Laboratory under the auspices of the U.S.
Atomic Energy Commission.)
SHAVER, DONALD L., and ARNOLD H. SPARROW, Biology Department, Brookhaven National
Laboratory, Upton, New York: The relationship between nuclear or chromosome volume and
rate of radiation-induced somatic mutation in higher plants.-A number of diploid species of
higher plants including Tulipa kaufmanniana, Tropaelum maius, Tradescantia ohiemis, Phaseolus
vulgaris, Antirrhinum maius, were selected to represent a wide range in nuclear volume (50-
1000 cubic microns) and chromosome size. Heterozygous lines were made for these species using
characters that would yield visible somatic mutations. Irradiations were performed under controlled
conditions, and rates of somatic mutation determined by means of scoring the frequency
and size of mutant sectors. Results to date indicate a close positive correlation between nuclear
volume or chromosome size and frequency of mutation or deletion of marker genes per roentgen.
This work supports the hypothesis that sensitivity to radiation injury is positively correlated with
nuclear or chromosome volume, and that induced somatic mutation rates in diploids can be
roughly predicted from their cytological characteristics. (Research carried out at Brookhaven National
Laboratory under the auspices of the U.S. Atomic Energy Commission.)
SIEGFL, ALBERT,
University of Arizona, Tucson.: Isolation of proteinless mutants of tobacco
mosaic virus.-Several workers have isolated mutants of tobacco mosaic virus which have altered
proteins following treatment with mutagenic agents. It seemed feasible that mutants might
also be induced which have a type of damage to genetic material which would preclude syn-
thesis of viral protein upon infection. Two such mutants have been isolated from a parent popu-
lation which had been treated with nitrous acid. The treated virus was inoculated directly to
tobacco seedlings at limit dilution so that at least half of the inoculated seedlings remained un-

ABSTRACTS 985
infected. Because virus nucleic acid, unprotected by virus protein, is known to be extremely
labile to the action of ribonucleases, the tobacco seedlings exhibiting symptoms were tested for
ease of transmission of the infection to local lesion hosts in the presence of a small amount of
pancreatic ribonuclease. Of 155 tobacco seedlings inoculated, 72 exhibited visible signs of virus
infection and of these two behaved peculiarly in that it was difficult to transfer the infection by
standard techniques. Phenol extracts of these two plants contained infectivity whereas buffer
extracts contained little or none. Extracts made by the technique of DIENER (Virology 16: 140,
1962) which is designed to yield both intact virus and free infectious ribonucleic acid, yielded
only ribonuclease-sensitive infectivity. The lack of ablity to induce the synthesis of virus protein
does not, apparently, limit the replicating ability of the virus nucleic acid in the host cell nor the
spread of the infectious principle from cell to cell.
SIMANTEL, G. M., J. G. Ross, C. C. HUANG, and H. D. HAENSEL, South Dakota State College,
Brookings, South Dakota: Somatic chromosome reduction in sorghum after colchicine treatment.
-Following treatment of sorghum seedlings of the variety “Experimental 3” with colchicine,
diploid mutant plants arise that breed true in subsequent generations. The production of diploid
mutants was found to be dependent upon the genotype as well as the presence of certain environmental
conditions after colchicine application. To explain the homozygosity of the mutants, it
has been proposed that a reduction of chromosomes to a haploid condition occurred with later
doubling to restore the diploid number. This was tested by treating seedlings heterozygous for
chromosome markers (reciprocal translocations) .-After treatment of 80 seedlings heterozygous
for the chromosome marker, three diploid mutants occurred. Since these mutant plants when
examined at diakinesis showed no configuration of four chromosomes, they must have been
homozygous at least for the two pairs of marked chromosomes. They had uniformly high seed
set in comparison to the semisterility noted in the other plants. The marked chromosomes of
two of these mutants were demonstrated to be same as the normal parent (male). The homozygosity,
therefore, could not have arisen as a result of se1fing.-The presence of homozygous
normal chromosomes identified in the mutants obtained after colchicine treatment demonstrates
the occurrence of somatic chromosome reduction followed by doubling, of at least the two marked
chromosomes followed in this study. It would be expected that the whole chromosome complement
would be involved in such a somatic reduction to explain the phenomenon of the appearance
of true-breeding mutants after colchicine treatment. (This investigation was supported in
part by research grants from the National Cancer Institute, U. S. Public Health Service (C2086)
and the National Science Foundation.)
SMITH, HAROLD H., Department of Biology, Brookhaven National Laboratory, Upton, L. I.,
N. Y.: Studies on the origin, inheritance and mutation of genic-cytoplasmic male sterility in
Nicotiana.-Second generation populations of the cross Nicotiana langsdorffii x N. sanderae
yield approximately ten percent male sterile segregants. None appear in the parental species,
reciprocal backcrosses of the F, to either parent, or in F, progeny of the reciprocal F, hybrid.
Experimental results were compatible with the hypothesis that male sterility is controlled in this
material by a cytoplasmic factor [ms], present only in N. langsdorffii; and two independent recessive
alleles, one contributed by each parent species. The dominant alleles, Rf, and Rf,, restore
pollen fertility. N. langsdorfii is [ms] Rf,Rf,rf,rf,; N. sanderae is [MF] rflrflRfeRfZ, and only
[ms] rf,rf,rf,rf, segregants are male sterile. The rf, allele is linked with approximately 13%
crossing-over to p, a gene from N. 1angsdorfiCii that inhibits anthocyanin pigmentation. Pollen
carrying the Rf, allele is at a disadvantage of about 1:4 in competition with rf, pollen. This
accounts for certain anomalous ratios observed as, e.g. ten percent than 6.25% male steriles in
the F,. Two genotypes were synthesized to study induced mutation of the cytoplasmic factor,
namely: male fertile [MF] rf,rf,rf,dz and male sterile [ms] rf,rf,rf,rf,. Plants of each were
exposed to chromic gamma irradiation of 100dday and seeds to 10,OOOr of acute gamma radiation.
Results of efforts to mutate [MF] rjlrflrferj, to [ms] rf,rj,rj,rj, and vice versa will be reported.

986 ABSTRACTS
(Research carried out at Brookhaven National Laboratory under the auspices of the U.S. Atomic
Energy Commission.)
SOKOLOFF, A., Department of Genetics, University of California, Berkeley, California: Linkage
groups in Tribolium castaneum.-Of the ten possible linkage groups in this species of flour beetle,
seven have been identified with the following genes: chromosome I (X) : lethal-1 (11), truncated
elytra (te), paddle (pd), red (r), miniature appendaged (ma), pygmy (py), divergent elytra
(due), spotted (sp) ; chromosome 11: pearl (p), pegleg (pg) ; chromosome 111: black (b) ; chromosome
IV: sooty (s), Bar eye (Be); chromosome V: jet (j), split (spl), microcephalic(mc);
chromosome VI: Microphthalmic (MO) ; chromosome VII: Distorted (Ds) .-The approximate
relative distances between the various genes are as follows: 1,-pd = 39; te-pd = 24; pd-r = 1;
pd-ma = 12; ma-py = 2; pd-sp = 46; due-py 6-36 units in various experiments at different
temperatures, the position of due being between py and sp. (te and ma are semilethal; te, due
and sp are incompletely recessive; py is a semidominant.)-In the autoYomes p-pg are about 30
units apart, pg being a semilethal; b is a semidominant; distance between s and Be = 25 units
(Be behaves as a dominant, recessive lethal) ; i and spl are 6-1 7 units apart; mc is 30 units away
from j but at present it is not known in which direction away from spl; MO and Ds are both
dominant, recessive lethals. (Supported by USPHS grants RG-7842 and RG-8942.)
SONDHI, K. C., Division of Genetics, New England Institute for Medical Research, Ridgefield,
Connecticut: Patterns of gene pleiotropy in morphogenetic processes of Drosophila.-Continued
selection for an increase and decrease in the number of bristles and ocelli in the ocelliless mutant
of Drosophila subobscura, which is variable for the number of bristles and ocelli on top of the
head, has revealed the pleiotropic nature of the mutant. Upward selection, after the wild-type
phenotype of bristles and ocelli had been reached, was effective in increasing the frequency of
(1) repeated bristles and ocelli, i.e., two or more structures lying close together at a site normally
occupied by one, (2) neomorphs, a novel pair of bristles normally absent in Drosophilidae but
present in a closely related family, Aulacigasteridae, and (3) of additional bristles and ocelli at
irregular sites, affecting in certain cases the positions of associated structures. In the downward
direction, selection was effective in eliminating central bristles and ocelli, after which little
progress was made. However, in the later generations of selection, additional marginal bristles
at irregular sites were seen, either interpolated between normal bristles or in positions involving
respacing of associated structures. The frequency of additional marginal bristles distorting the
positions of associated bristles was found to increase with an increase in the frequency of genes
for the lower number of structures.-A hypothesis is postulated to explain the nonhomeomorphic
distortion of structures in terms of primarily an unvarying “prepattern” which determines the
positions of these structures, and of a common “precurwr” of bristles and ocelli which must be
present in the required amount if structures are to be formed. It is suggested that flies having the
amount of precursor within a certain range produce phenotypic changes only by varying that
amount. Individuals with amounts of precursor outside this range produce nonhomeamorphic dis-
tortion of structures by changing the prepattern, i.e., by changing the number of shapes of the
peaks of the prepattern. Since such phenotypes were only seen at the two extremes of the mutant
expression, it is suggested that the primary effect of the ocelliless gene is to alter the amount of
precursor and that this in turn may change the prepattern.
SPOFFORD,
JANICE B., University of Chicago, Chicago, Ill.: Direct and parental phenotypic
effects of a euchromatic uariegation-suppressor locus in D. me1anogaster.-A IIIL locus (42%)
contmls the pigment intensity difference between two otherwise identical w“ stocks. The mutant,
Su-V, reduces variegation at other loci in the same wm rearrangement and also reduces variega-
tion, at least for white, in several other rearrangements, and hence may belong to the same cate-
gory of nonspecific influences on position-effect expression as extra Y heterochromatin.-Flies
genotypically +/+, +/Su-V, and Su-V/Su-V and also genotypically uniform offspring of +/+,

ABSTRACTS 987
+/Su-V and Su-V/Su-V parents were coppared in detail for frequency and intensity of eye
pigmentation, using y w/Y sons of YS w yYLy+/Y 8 8 x y w/y WO 0. Dp(z~F)*~4.~~~, a short
insertion from the X into IIIL proximal heterochromatin, provided an autosomally inherited wm
locus. Heads were squashed singly and chromatographed. Absorption by drosopterin was measured
with Densichron model 4-51-4, totaling 3384 measurements. In summary: (1) all three
genotypes are easily distinguishable, +/+ being the most variegated, Su-V/Su-V the least; (2)
father’s Su-V genotype is irrelevant to offspring phenotype; (3) offspring of Su-V/Su-V mothers
are less variegated than those of +/Su-V mothers, and the latter offspring are less variegated
than those of +/+ mothers; (4) a paternally-derived Dp variegates less than a maternallyderived
Dp. All three of the foregoing effective conditions jointly determine the phenotype of a
fly.-A previously reported anomaly in the parental-source-of-Dp effect, (4), in one Dp stock
(“Dpf”) is attributable to the presence of Su-V on its Dp chromosome. “Dpf” and recombinants
from Su-V +/+ Dp behave identically. (Supported by the U.S. Public Health Service.)
STADLER, JANICE, and JOHN W. GOWEN, Iowa State University, Ames, Iowa: Patterns of reproductivity
of different strains of mice under continuous irradiation.-Latent effects of acute
irradiations, dependent on genotype and dose, may not be manifest until the latter part of life.
Similar delayed effects are of concern should they accumulate in successive generations of mice
that are under frequent irradiations even though the daily exposure dosages may be small. Mice
from several inbred strains have been exposed to gama ray radiation from a CoGO source
throughout their lifetimes and the lifetimes of their descendants in each successive generation.
The gamma radiation has been given at eight different dose levels over exposure periods averaging
22 hours per day. Sterility resulted from dosages of over 3r per day. Adequate reproduction
to maintain the germ line is obtained from mice exposed to 0.6 to 2.0r per day. Up to 14 generations
have been reared under continous radiation. Following the original single pair nonbrother
by sister mating exposed, all successive generations have been bred within litter matings.
Four strains thus far have attained ten generations in this atmosphere of continuous radiation.
Samples of progeny of the tenth generation litters are under test for life-span, fertility, viability
of young, disease resistance, dominant and recessive visibles, and sterility. The performance of
these lines will be discussed. (This work has received assistance from Contract AT(11-1) from
the Atomic Energy Commission. Journal Paper No. 5-4362 of the Iowa Agricultural and Home
Economics Experiment Station, Ames, Iowa. Project No. 1180, 1187.)
STENIUS, CHRISTINA, LAWRENCE C. CHRISTIAN, and SUSUMU OHNO, City of Hope Medical
Center, Duarte, California: Chromosome complements of the turkey and the pheasant compared
with that of the chicken.-While the recovery of viable hydrids between two species indicates
their close taxonomical relationship, the sterility of the F, hybrids suggests, among other things,
structural differences between the chromosome complements. Indeed, a chromosome study on
horses, donkeys, and mules revealed a great number of morphological discrepancies between
the complements of horses and donkeys.-Since an intergeneric hybrid between Gallus domesticus
and Phasiunus colchicus and an interfamilial hybrid between Gallus domesticus and
Meleagris gallopauo have been reported, we undertook a study of the chromosome complements
of the pheasant and the turkey, comparing details with that of the domestic fowl of both sexes
at mitosis and meiosis. The autosomal complements of the three species have very little in common,
while the Z chromosomes are identical not only in size but in centromeric loci and pachytene
banding as well, as illustrated by the accompanying series of photomicrographs. (Supported
in part by a National Science Foundation grant C-17601.)
STRAUSS,
B. S., University of Chicago, Chicago, 111.: “Recouery” of DNA from the effects of
alkylation.-The transforming activity for linked histidine and indole loci of DNA extracted
from a methionine-requiring strain of B. subtilis is reduced about tenfold per unit of DNA by
treatment of cells, with 0.025 M methylmethanesulfonate (MMS) for 30 minutes at 37C. The

988 ABSTRACTS
treatment reduces the viable count of 0.1 of the original and induces a revertant frequency of
The amount of cold acid insoluble, diphenylamine reacting material (DNA) present in treated
and nontreated cultures is identical. Transforming activity of extracts prepared from MMS
treated cells is heat sensitive and about 85 percent of activity is lost after 1 '/e hours at 50C; DNA
from nontreated cells is unaffected and the activity of nontreated DNA is not sensitized to heat by
mixture with DNA from MMS treated cells.-Incubation of cells in amino acid supplemented
medium leads to an increase in extractable transforming activity. The increase in activity of
extracts from nontreated cells is accompanied by an increase in cellular and extractable DNA.
Transforming activity from MMS treated cells more than doubles on incubation with little or
no net DNA synthesis. The heat sensitivity of transforming DNA from MMS treated cells de-
creases after incubation of the cells.-Turnover of DNA in the absence of net DNA synthesis can
be demonstrated in MMS treated cells. C-I4 thymidine is incorporated by MMS treated cells in
an alkali stable, hot acid soluble form. Thymidine incorporation increases steadily in MMS
treated cultures without lag under conditions where the net DNA content remains constant or
drops slightly.-The experiments may be interpreted to mean that a small fraction of new DNA
of normal activity and heat sensitivity is synthesized by MMS treated cells using the alkylated
DNA as a template. (Work supported by a grant (RG 7816) from the National Institutes of
Health.)
STUTZ, HOWARD C., Brigham Young University, Provo, Utah: Asynchronous meiotic chromosome
rhythm as a cause of sterility in Triticale.-Very little chromosome affinity is evident in
meiotic prophase in the sterile hybrids Secale cereale x Triticum aestiuum and Secale africanum
x 2'. aestiuum. Good pairing occurs in the colchicine induced amphidiploids but fertility is low.
Precocious chromosomes in pachytene and diplotene, lagging chromosomes during anaphase I
and anaphase I1 and abundant micronuclei in microspores of the amphidiploids suggest asynchronous
meiotic rhythm of the parental chromosomes to be the principle factor contributing to
the resultant sterility.
SUNDER, J. H., A. H. Gibson Laboratory, Univ. of Pittsburgh, Pittsburgh, Pa.: Inheritance of
cholesterol metabolism in the rabbit.-Because of the high intrafamily correlation coefficient
and the direct response to selection on the total serum cholesterol value in rabbits, it is concluded
that cholesterol metabolism is under genetic control. As an inherited characteristic, it is probably
of the multifactorial or polygenic type.-Standard experimental procedures of feeding added
cholesterol to increase the total serum cholesterol and produce arteriosclerotic lesions as well
as injecting sodium heparin to lower the total serum cholesterol value elicits a variable response
when randomly selected rabbits from diverse sources are compared as a group. This variation
can be measured as maximum and minimum levels attainable on a standardized dosage, and
length of time to reach the extremes. While the latter is not as variable as the former, it is
significantly different. There was no correlation between the extreme indices and the time factor
in the animals tested.-Results of experiments now in progress will be reported testing the
intrafamilial and interfamilial correlation of the normal physiological value with the two
stressful conditions and their effect on the normal value.-Other contributory and related physiological
indices such as Ix31 retention, 1131 conversion ratios and total triglyccride levels will
also be compared in the normal and stressed animals.-It is hoped that investigation, such as
this, into more than one parameter of a metabolic sequence may help to clarify the variable
picture seen in some hereditary clinical syndromes.
SUYAMA.
Y., University of California. San Diego, La Jolla. California: Properties and apparent
homogeneity of a complementation enzyme in tryptophan synthetase system of Neurospora.-The
extract from a heterocaryon between two allelic td mutants (td-3 and td-104) can catalyze the
conversion of idole to tryptophan, whereas extracts from each mutant as well as mixture of the
two cannot. The activity in the extract from the heterocaryon precipitates at a higher ammonium

ABSTRACTS 989
sulfate concentration than the activity of the wild type. Further, the heterocaryon enzyme is
significantly more heat labile than wild-type enzyme, and Km’s for pyridoxal-phosphate and
indole in the reaction are tenfold higher in the complementation than in wild-type enzyme.-
The independent extracts of the above two mutants possess CRM, a protein serologically related
to tryptophan synthetase. The CRM’s however, differ in their ammonium sulfate fractionation
patterns and heat sensitivities. The two different ammonium sulfate fractions made from the
heterocaryon extracts contain different amounts of each CRM. No significant differences were
found between the two fractions in Km’s for serine, pyridoxal-phosphate and indole, and their
heat sensitivities. From these studies, it is concluded that the complementation enzyme is differ-
ent from wild type and perhaps a single species of the active complementation enzyme is
produced.
SUYAMA, Y., and D. M. BONNER, University of California, San Diego, La Jolla, California:
Complementation, mutation and enzyme alteration in the tryptophan synthetase system of
Neurospora.-Mutations at the locus which controls the formation of tryptophan synthetase
produce diverse alterations of the enzyme. It is known that extracts from some mutants possess
CRM (a protein serologically related to tryptophan synthetase), while others do not; these are
designated as CRM’ and CRM- mutants, respectively. Differences are also found among CRM’s
in terms of their ability to catalyze the three reactions which are catalyzed by wild-type tryptophan
synthetase.-It is of interest to relate the complementation properties of these various
mutants to the nature of their enzyme alterations and to the location of the mutational sites
within the locus.-The present studies demonstrated that complementation is not found between
mutants possessing catalytically similar CRM or between CRM- mutants and that three complementing
units can be assigned in terms of genetic segments and catalytically competent segments
of the enzyme. Further, the observation that the complementation map is not linear,
suggests that complementation is not a direct reflection of the primary structure of the protein
but rather a measure of complex interactions between functionally competent segments of the
polypeptide.
SUZUKI, D. T., Biology Division, Oak Ridge National Laboratory, Oak Ridge, Tenn.: A pos-
sible role of asynapsis in interchromosomal effects on crossing-over in Drosophila me1anogaster.-
Chromosomes having interchromosomal effects on crossing-over can be divided into two classes
based on their pairing configurations. The classic category is characterized by the formation of
synaptic loops or rings: inversion heterozygotes and homozygotes; ring X heterozygotes and
homozygotes; tandem metacentric and acrocentric compond Xs. The chromosomes in the second
class do not synapse as loops and have a reduced frequency of crossing-over: reversed acrocentric
(RA) compound X with no free Y; reversed metacentric with a Y; two rod X’s with a Y, a free
or attached proximal duplication (BS), or a free distal duplication (@). It is suggested that the
arms of these chromosomes fail to pair with a definite frequency owing to intrinsic chromosome
properties (RA/O) or competition with an extra homologous element.-Crossing-over in chromo-
some 3 was measured in females heterozygous for either FM-6, an X chromosome rearrange-
ment containing eight breakpoints, or SM-5, a second chromosome with 13 breakpoints. It is
assumed that these complex rearrangements fail to pair with their normal homologs because
of mechanical difficulties. Both rearrangements increase crossing-over in chromosome 3, the
magnitude of increase in the regions adjacent to the centromere being as great as in the centro-
mere region.-It is suggested that asynapsis of one chromosome pair is a sufficient condition
for causing an increased frequency of crossing-over in another pair. A critical test of this hy-
pothesis, measuring autosomal crossing-over in exchange (synapsed) and nonexchange (asyn-
apsed) reversed acrocentric progeny, will be reported.
SUZUKI, NORIO,
and I. L. KOSIN, Washington State University, Pullman, Wash.: The age of
RBC donors and the immunological differences in genetically isolated lines of domestic turkeys.-

990 ABSTRACTS
Four lines of genetically isolated turkeys (one random-bred, and three experimentals, each
selected for a single trait), six generations removed from a common base population, have
demonstrable differences for several blood factors. When tested at Serology Laboratory, Uni-
versity of California, Davis, lines 3 and 4 (selected for egg production and hatchability, re-
spectively) were found to be devoid of factor Q, common in lines 1 and 2 (random-bred and
large-body size, respectively). Tests at WSU have revealed quantitative differences between
lines 1 or 2 and lines 3 or 4 for F and M antigenic complexes: there is relatively more M and
less F in lines 1 and 2 than in lines 3 and 4. When antiturkey rabbit serum B, produced by
injecting RBC from 2 to 4 month old turkeys (I), was, first, incompletely absorbed with RBC
of (1) or of 10 to 12 month old turkeys (2), differences in RBC “absorption power” were re-
vealed: RBC of (2) showed lower values. Reverse was true for antiturkey rabbit serum W, ob-
tained by injecting (2) RBC and then partially absorbing the serum with (1) or (2) RBC. A
tentative explanation, supported by other related observations at this laboratory, is that (2) RBC
carry more M antigens and less F than (1 ) RBC. Thus, lines 1 and 2 are antigenically closer to
(2)-type RBC and lines 3 and 4 to (1)-type RBC. (Project 1600, supported, in part, by funds
provided for biological and medical research under State of Washington Initiative No. 171.)
TANO, S., and A. B. BURDICK, Purdue University, Lafayette, Ind.: Female fecundity of Drosophila
melanogaster second chromosome recessive lethal heterozygotes in homozygous and heterozygous
genetic background.-Eighteen spontaneous lethals were introduced separately to
homozygous S-2 genetic background by a system which allowed an average of 13.7% residual
heterozygosity from the original lethal stock, i.e., a section averaging 39.4 crossover units surrounding
the lethal remained unsubstituted by S-2. Fifty l/+ females, divided into five replications,
were observed for egg production during the third through sixth days after eclosion.
Heterozygous background was produced by crossing the S-2 background strains with W-109, an
unrelated homozygote.-In homozygous background where the female fecundity (f) of S-2
is taken at 1.000, the mean f of the 18 lethal heterozygotes was 1.475, all values being greater
than 1.19. When the f values were corrected for the 13.7% residual heterozygosity, the mean
f became 1.280 and only one of the 18 values fell below 1.0. Five of the corrected f values were
considered to be significantly greater than 1.000, while the group as a whole could be considered
to represent samples drawn from a population the over-all mean of which was greater than 1.000
since 17 of the 18 values fell above 1.000.-1n heterozygous background, where the hybrid
S-2/w-109 was taken as 1.000, the mean f value was 0.961, all values being less than 1.05, 11
of them less than 1.000. There was no rank order correlation between f values obtained from
homozygous and heterozygous background.-Larval, or preadult, viability has been the usual
means of estimating the consequences of heterozygosity for deleterious genes, whereas f is equally
important in over-all fitness. The present study indicates that the f consequences are relative to
the degree of heterozygosity of the genetic background. (Supported by NIH E-1428.)
TAUB, STEPHAN R., Harvard University, Cambridge, Mass.: The effect of nuclear genes on
nuclear differentiation in syngen 7, Paramecium aure1ia.-A mutant strain (m7-1) restricted
to mating type XI11 arose following ultraviolet irradiation of type XIV cells of a wild-type
strain (d7-1) capable of expressing either mating type XI11 or XIV. In the progeny of hybrids
formed between the mutant and wild-type strains the restriction to type XI11 is observed to
segregate in a 1 : 1 ratio from the ability to express either type. Thus a mutation at a single locus
is sufficient to account for the origin of m7-1. The mutant gene at this locus is designated n, its
wild-type allele, N. The progeny of crosses of heterozygotes (N/n) on mating type XIV to
stock 38, strain homozygous for mtxl11, a gene which, like n, restricts homozygotes to type
XIII, are capable of expressing either type XI11 or XIV. Breeding analyses of these progeny
reveal that the N and mt loci are unlinked.-As is the case with homozygotes for mtXIII (TAUB,
Genetics 44:541, 1959), progeny genically competent to express either mating type which derive
their cytoplasm from stock m7-1 (n/n) become type XIV. However, in contrast to the case at
the mt locus, genically competent cytoplasmic progeny of heterozygotes of type XI11 become

ABSTRACTS 991
XI1I.-These observations can be explained by a hypothesis which assumes that: (1) the mt and
N loci control separate steps in a sequence which results in the production of the XIV mating
type substance; (2) the ability of the macronucleus to differentiate to control only one of two
alternative mating type potentialities reflects the ability of the wild-type allele at the mt locus
(or, less likely, at the N locus) to be repressed when differentiation occurs in the presence of a
hypothetical substance, “R’; (3) “R” is a precursor of the XIV mating type substance. (Sup-
ported by a grant from the Natisonal Science Foundation.)
THOMPSON, PETER E., Iowa State University, Ames, Iowa: Synaptic modification of dominant
lethal frequencies after irradiation of the Drosophila testis.-Increases in the mutability of unpaired
chromosomes have led to the interpretation (THOMPSON, Genetics 47:337, 1962) that the
synapsis of homologous chromosomes is a major factor in the repair of radiation induced chromosomal
damage. This hypothesis is subtantiated by the present data on the production of dominant
lethals among males in which complex structural heterozygosity (presence of multiple inversion
SM5) has created almost total asynapsis of one major pair of chromosomes. Egg development
among one-day broods from such males after X-ray treatment gave evidence of an appreciable
increase in dominant lethals of meiotic origin, in comparison with males lacking structural heterozygosity.-The
brood pattern of dominant lethals from irradiated control males shows a
plateau of maximum frequency from early meiosis to spermatid stages, i.e., among sperm sampled
from the fifth to the eighth day after irradiation. Broods from irradiated SM5 males gave
similar frequencies for premeiotic and postmeiotic stages, including the fifth and tenth brood
periods, but during days 6-8 about twice as many dominant lethals were scored among these
lines. If dominant lethals may be equated with highly aberrant rearrangement or loss of chromosome
fragments, asynapsis appears to contribute markedly to gross genetic damage during
meiosis. (Supported by Grant RG-8912 from the National Institutes of Health.)
TUVESON, R. W., Department of Botany, University of Chicago, Chicago 37, Illinois: Hyphal
tip isolation as a criterion for heterocaryosis.-Specific heterocaryons between auxotrophic strains
of Cephalosporium mycophilum exhibit selection for the incorporation of one of the nuclear
types into the conidia produced by the heterocaryon. Growing the specific heterocaryons on
supplemented minimal medium resulted in altered nuclear proportions and recovery of the
minor nuclear component. Hyphal tip isolations from one of the heterocaryons exhibiting selection
when grown on minimal medium were incapable of continued growth on minimal medium
although tips transferred to complex medium grew vigorously. These results suggested that the
hyphal tips were homocaryotic for the dominant nuclear component. However, the heterocaryotic
nature of the mycelium had been previously established by the isolation of a somatic diploid
from which recombinants were subsequently recovered. Manipulating concentrations of supplements
in the minimal medium on which the heterocaryon was grown has resulted in the isolation
of hyphal tips able bo grow on minimal medium. Supplementation of the medium presumably
altered nuclear proportions, thus allowing for the isolation of hyphal tips capable of growth on
minimal medium. In species of Fusarium, isolation of hyphal tips from specific hetercaryons
exhibiting selective incorporation of nuclear types into conidia revealed that a high proportion
of these tips were capable of continued growth on minimal medium. These results suggest that
selection was not severe enough in these heterocaryons to preclude the isolation of heterocaryotic
hyphal tips. These experiments indicate that the inability to isolate hyphal tips capable of continued
growth on minimal is not conclusive evidence against heterocaryosis, but may reflect
severe selection resulting in a high proportion of homocaryotic tips. The results with Fusarium
indicate that selective incorporation of nuclei into conidia need not result in homocaryotic tips.
UNDERKOFLER, JUDITH, and M. R. IRWIN, University of Wisconsin, Madison, Wisconsin:
Inieraction products of new combinations of genes in species crosses of Co1umbidae.-A hybrid
substance is defined as an antigenic product of the erythrocytes of an individual (species hybrid

992 ABSTRACTS
or heterozygote) which is not present in either parent. It can be demonstrated by agglutination
of the cells of the hybrid following absorption of antisera against the hybrid with erythrocytes
of both parental types.-Repeated backcrosses to Streptopeia risoria of species hybrids and selected
backcross hybrids from respective matings of chinensis, orientalis, and senegalensis with risoria
have resulted in the establishment of individuals essentially identical to risoria with the exception
of their content of a gene or genes from one of the other species for the antigen number 8: ch-8
(formerly called d-If), or-8, or se-8. The contrasting character of risoria is designated ri-8. The
cells of each of the three kinds of heterozygotes (ch8/ri-8, or-8/ri8, and se-8/ri-8) invariably
carry a hybrid substance peculiar to itself, but the respective homozygotes produced by inter se
matings do not.-Matings among the three homozygotes have produced two new combinations,
ch-8/se-8, and ch-8/or-8. The cells of each of the three combinations, ch-8/ri-8, ch-8/se-8, and
ch-8/or-8, possess a hybrid substance which is related to the others; but each contains antigenic
specificities peculiar to itself. Thus, it appears that different combinations of the causative genes,
or of genes linked to them, produce different interaction products.
VARMA. BASUDEO, ALAN CASPAR, and W. RALPH SINGLETON, Blandy Experimental Farm, University
of Virginia, Boyce, Virginia: Effect of chronic gamma radiation on proembryos of corn.
-During the summer months of 1960, corn plants of inbred Pr line which are susceptible to the
leaf spot disease of Helminthosporium carbonum were grown in pails. Twenty-four hours after
self pollination, they were moved into the gamma field and were irradiated for one day giving
a total dose of 1000r. In a few cases, ears showed poor seed settings. In the summer of 1961, all
the seeds obtained from irradiating at the proembryo stage were planted in the field and selfpollinations
were made. Mature plants showed differences in their height, abnormal growth
showing signs of chromosomal losses, pollen sterility, etc. In this spring F, seeds have been
tested in the green house for any mutations produced. In a number of cases it seems that gene
mutation have been induced. Seedlings have segregated for green and yellow-green characters
in a 3:l ratio. Another mutant observed is dwarf plants, which also segregated in a 3:l ratio.
These dwarf mutants died after 20-25 days. Other than these, albino, luteus and japonica type
mutants have appeared. The great frequency in the mutation rate produced by semiacute gamma
radiation at the proembryonic stage is worthy of notice. Work is in progress to test these F, seeds
for any resistance induced to Helminthosporium carbonum disease. Results will be discussed.
Complete data will be presented and the fundamental importance of these findings to radiation
genetics and plant breeding will be discussed.
VOGEL, H. J., Institute of Microbiology, Rutgers University, New Brunswick, N.J.: Lysine
synthesis in some ‘‘algal fungi” and blue-green algae: phylogenetic implications.-Among a
number of phycomycetes tested, those having either anteriorly uniflagellate or biflagellate ZOOspores
synthesize lysine via 2,6-diaminopimelic acid (DAP), whereas those having either posteriorly
uniflagellate zoospores or aplanospores produce lysine via 2-aminoadipic acid, as do
higher fungi and euglenids (VOGEL, Symposium on Evolutionary Biochem., Fifth Intern. Congr.
Biochem., Moscow, 1961). These studies carried out with the aid of diagnostic radiocarbon
tracers (3- and &labeled aspartic acids and l-labeled alanine) have now been extended to the
following phycomycetes with anteriorly uniflagellate or biflagellate zoospores: Rhizidiomyces
sp. (Hyphochytriales) , Thraustotheca clavata (Saprolegniales) , Sapromyces elongatus (Leptomitales),
Sirolpidium zoophthorum (Lagenidiales), and Pythium ultimum (Peronosporales) .
All these organisms, in line with the above-mentioned generalization, use the DAP-lysine pathway,
and thus participate in an evolutionary continuum which includes green algae, as well as
bacteria and vascular plants (VOGEL, op. cif.). Similar experiments have now shown that the
DAP-lysine pathway is also employed by the blue-green algae, Nostoc sp. and Plectomma
boryanum. (Aided by the National Science Foundation and the Office of Naval Research.)
WALTERS, MARTA SHERMAN, Santa Barbara Botanic Garden and University of California, Santa
Barbara, Calif.: A nuclear body in meiosis of Bromus.-A structure tentatively called a “nuclear

ABSTRACTS 993
body” is observed in meiosis of 19 species of Bromus, representing five sections of this genus. The
nuclear body is first visible at pachytene, and remains visible for periods ranging from metaphase
I to the quartet, the duration varying from species to species. It decreases in size during later
stages of meiosis. The nuclear body is included in the prometaphase clump, is excluded from the
spindle, and is generally located near the pole at metpahase I; it does not divide, and is included
in only one cell of the dyad and one cell of the quartet. This structure varies markedly in size
among species of Bromus; there is some relationship, though not a precise one, between its size
and the chromosome number. The nuclear body appears to consist of numerous small, thin-
walled globules or of relatively few thick-walled globules, or a combination of the two. The
nuclear body is not associated with the nucleolus, nor with the nucleolar organizing regions of
chromosomes. It is sometimes in contact with a bivalent at pachytene, and this may involve a
terminal, subterminal or interstitial region, and sometimes bivalents with different chromomere
patterns. The nuclear body is more often in contact with bivalents in some species than in
others; thus the contacts may not be entirely fortuitous. The nuclear body has not to date been
observed in mitotic cells. Its chemical constitution is now being investigated.
WEILER, CONRAD P., City of Hope Medical Center, Duarte, Calif.: Sex chromosome behavior
of amphibians. I. Ram pipiens-Genetic studies and breeding experiments on fishes, amphibians,
and reptiles have shown the sex-determining mechanism to be either the XY-XX type
(male heterogamety) or the ZZ-ZW type (female heterogamety). Studies also showed many
similarities in genetic constitution between the X and the Y, or the Z and the W. Cytological
studies reported so far support the relatively undifferentiated state of the sex chromosomes of
lower vertebrates.-In order to elucidate the mechanism which prevents extensive crossing-over
between the female-determining X and the male-determining Y during meiosis of the heterogametic
sex, mitotic and meiotic figures of the leopard frog were studied.-Alignments of
metaphase chromosomes from Rana pipiens show that both sexes have 13 identical pairs; thus
the X and Y are morphologically identical. During spermatogenesis, no particular pair of
chromosomes exhibits positive heteropycnosis as does the mammalian sex pair, but chiasma frequency
for all bivalents is definitely lower in males than in females. Since isolation of factors
determining opposing sexes is crucial to the preservation of a genetic sex-determining mechanism,
it is proposed that in Rana pipiens the isolation is accomplished by the lower chiasma rate observed
during meiosis in the heterogametic male. (This work supported in part by PHS grant
CRT-5089.)
WEIR, J. A., and G. SCHLAGER,
University of Kansas, Lawrence, Kansas: Selection for total
leucocyte count in the house mouse.-A high leucocyte line (LCH) and a low line (LCL) were
selected from an outbred strain designated T. Selection was continuous for 25 generations and
was based on family and individual merit coupled with intensive inbreeding (mostly full-sib
matings). Selection was effective from the onset with a maximum difference of over 100 percent
of the original leucocyte number by generation 13 (LCH 17,500, LCL 4,000 cells per nun3).-
Although the selection differential was uniform in the two lines, the intensity of response was
greater in the LCH with the initial number of leucocytes doubled by generation 13. Response
in the LCL was more gradual but continued until the end of the experiment. The asymmetry
of response was statistically significant. Leucocyte counts in the T strain corresponding to gen-
erations 2, 5, 7, IO, and 16 remained relatively constant to generation 10 (mean 8590) but
dropped to 5105 in generation 16. The downward trend in the three lines after generation 13
may be due to environmental factors. Ninety-five percent confidence limits set to the estimate of
realized heritability for the first 13 generations were 14.7 and 22.7 percent. The selected lines
did not differ significantly in two components of fitness measured: numbers of progeny born or
weaned, and weaning weight.-Leucocyte numbers confer resistance to irradiation, but not to
artificial infection with mouse typhoid. The LCH and LCL strains were both more susceptible to

994 ABSTRACTS
mouse typhoid than the outbred T. (Work supported by U. S. Public Health Service Research
Training Grant 2G-246.)
WIJEWANTHA, RONALD T., and G. LEDYARD STEBBINS, University of California, Davis, California.:
Developmental genetics of the agropyroides mutant in barley.-A mutant affecting spike
morphology was recovered from a dalapon treated field of six-rowed barley, variety California
mariout. F, progeny from reciprocal crosses showed single factor inheritance with the mutant
behaving as a recessive.-The upper parts of mutant spikes bear nodes with a single spikelet and
with the glumes placed laterally rather than dorsally. This produces a morphological resemblance
to Agropyron (or Triticum). The name Agropyroides, and the gene symbols ag ag, are therefore
suggested for this mutant.-Agropyroides homozygotes show 100% penetrance and variable
expressivity. The ug gene inhibits development of lateral spikelet components during early differentiation.
At comparable nodes on a developing spike, the central spikelet primordium grows
much faster than that of the lateral spikelet, the growth ratio being 13:2, as compared to 7:2
for normal spikes.-When crossed reciprocally to the two-rowed barley variety, Atlas deficiens,
agropyroides, showed a modified dihybrid segregation in the F,, since two-rowed is incompletely
dominant over six-rowed.-On a six-rowed background, ag decreases the number of spikelets per
node in the upper half of the spike, but on a two-rowed deficiens background the opposite effect,
increase in spikelet number, is produced at some of these nodes.
WOLFF, G. L., The Institute for Cancer Research, Philadelphia, Pa.: Body and tail length
differences between yellow (A’a) and nonyellow (aa) mice in parabiosis.-The existence of
hormonal differences between (AYa) and nonyellow(aa) mice has long been suspected. If such
differences exist, they might be detectable in parabionts. Inbred yellow and nonyellow mice from
the YS/ChWf strain were joined parabiotically at four weeks of age with littermates of the
same sex in three combinations: AYa:AYa, AYa:aa, aa:aa.-By 27-31 weeks of age the bodies,
exclusive of the tails, of the yellow mice were longer (P

ABSTRACTS 995
possibly third) mitotic wave also appears, starting at about 28 hours. Thus, even in the slowly
proliferating forestomach, cells which have divided once have a certain tendency to divide again
within a very short time. (Research carried out at Brookhaven National Laboratory under the
auspices of the U.S. Atomic Energy Commission and supported by U.S. Public Health Service
Fellowship No. CF-14, 272 from the N.I.H.)
WUNDERLICH, JOHN R., and LEONARD A. HERZENBERG, Department of Genetics, Stanford
University School of Medicine, Palo Alto, California: A second gamma globulin isoantigen (allotype)
in the mouse.-A gamma globulin isoantigen was reported to be present in serum from
the inbred mouse strains “BALB/c,” C3H/He and “Champagne-Glaxo” but absent from the
serum of “C57BL” (KELUS, A., and J. K. MOOR-JANKOWSKI, Nature 191:1405, 1961). We have
found a second gamma globulin isoantigen demonstrable by immunoelectrophoresis on cellulose
acetate. Antiserum from BALB/c animals immunized with the globulin fraction of C57BL/6J
serum forms a single precipitin line in the gamma globulin region of the electrophoregram with
serum from C57BL/6J and also from C57BL/Ka, C57BWlO.l and B10.D2. It does not react detectably
with serum from BALB/c, or A/J, C3H/Sn, DBA/2J and CBA/J. The antigen is
present in all tested F, progeny from the mating of a positive by negative strain. Appropriate
backcrosses have been set up.-A sensitive test has shown this isoantigen to be associated with
antibody activity. When a C57BL/Ka antiserum to the collphage T2 is used as antigen in reaction
with the BALB/c antiglobulin serum, a specific loss of the phage-neutralizing activity
results, indicating that the isoantigen is on antibody molecules.
YAMADA, YUKIO, and A. E. BELL, Purdue University, Lafayette, Indiana: Selection for 13th
day larva weight in Tribolium under two nutritional 1euels.-Selection for large and small
13th-day larva weight in Tribolium castaneum has been investigated in order to evaluate the
effectiveness of various selection methods and the importance of genotype by environment interaction
under two different nutritional levels. In addition to an unselected control population,
there were eight experimental populations as follows: GL = selected large based on sib record
under the good level each generation; PL = selected large under poor level each generation;
-
GPL = selected large on average performance under both levels; GPL = selected large under
good and poor levels in alternating generations; and similar four populations for small direction.
Each population was reproduced by 4.0 single pair matings each generation under standard
wheat medium. Selection was made on the basis of full sibs reared either under good, poor, or
average of both levels, depending on the selection methods. After choosing the best eight
families out of 40, five males and five females from each selected family were taken from the
standard medium. They were mated at random with the restriction that full-sib matings are
avoided. Therefore, each family has full-sib records under both environments, and any specific
environmental carry-over effect through parents is completely removed by the use of sib selection
from the standard medium.-Heritability of the selected trait in the base population both
under good and poor levels of nutrition was estimated to be roughly 20-25% and the genetic correlation
was about 0.50 (HARDIN 1962).-Effectiveness of the selection methods and role of interaction
will be discussed. (Supported by a grant from the National Science Foundation.)
YANAGISAWA, KEIKO, (Introduced by FRANCIS J. RYAN), Columbia University, New York, New
York: The simultaneous accumulation of RNA and of a repressor of ,&galactosidase synthesis.-
The methionine-requiring mutant, 58-161, of E. coli, continues to synthesize RNA even after
being deprived of all exogenous methionine. The effect of methionine starvation on the formation
of P-galactosidase was studied using this strain. After methionine starvation, a long lag was
observed in /3-galactosidase formation, although total protein started to increase immediately
upon restoration of methionine. This delay was not observed in E. coli 15 hismet-, in which
RNA is not synthesized during methionine starvation. If the former strain was deprived of a
carbon source along with methionine, RNA did not increase during starvation and no delay was

996 ABSTRACTS
observed in p-galactosidase production. This characteristic lag was not observed in a constitutive
mutant of E. coli 58-161. Therefore, it seems that, in E. coli 58-161, a repressor of ,&galactosidase
accumulated concommitantly with RNA during methionine starvation. This repression is how-
ever, not reversible by an inducer of P-galactosidase.
YOON, C. H., and S. LIZIO, Boston College, Chestnut Hill, Mass.: Evidence of incorporation of
tagged DNA extracted from thymus glands into germ cells of recipient mice.-DNA of the
thymus glands of mice was tagged with P32 and was extracted. This extracted DNA was then
injected into gonads of recipient mice. Evidence that indicates that this tagged DNA was incor-
porated into DNA of germ cells of recipient mice was obtained.
YOSHIKAWA, HIROSHI, and NOEKIRU SUEOKA, University of Illinois, Urbana, Ill.: Mechanism
of chromosome replication in Bacillus subti1is.-A series of experiments were designed to test
two major alternative models of chromosome replication by using genetic transformation system
of B. subtilis. Model A (random-in-time replication) : replication of DNA in the chromosome
occurs simultaneously in the whole region of the chromosome without any oriented sequence
along the chromosome. Model B (oriented replication) : replication of DNA starts from one or
both ends of the chromosome and proceeds orderly. The principle of our experiment is to culture
a wild type strain in a heavy meclium containing deuterium and nitrogen-15, and transfer to a
light medium (H20, NI4). Cell samples are taken at 0, %, K and 1 generations after the transfer.
DNA from each sample is centrifuged in CsCl solution, and heavy and hybrid DNA molecules
are separated by collecting single drops from the bottom of the centrifuge tube. Measuring the
specific transforming activity (STA) of 12 different auxotrophic markers in heavy and hybrid
DNA molecules, it is predicted that if the random-in-time replication model is right, the STA's
of both heavy and hybrid DNA should he similar, while in the oriented replication model there
should be difference in STA's between heavy and hybrid DNA. Moreover, in the latter model,
each marker should give a distinct ratio of STA's in the two DNA, depending on the location of
the marker in the chromosome. The experimental results so far obtained are consistent with the
oriented replication model. Results of further experiments on this line will be presented. (This
work is supported by National Science Foundation grants G-15080 and G-18745.)
ZALOKAR, M., University of California, La Jolla, Calif.: The role of nucleolus in the production
of ribonucleic acid.-The incorporation of H3-uridine into RNA of oocyte nuclei of Blatella
germanica was studied by autoradiography. When oocytes were incubated in H3-uridine for
four to 16 minutes, the newly formed, labeled RNA appeared in both nucleoli and chromosomes.
Nucleolar RNA was first observed in several spots at the periphery of the nucleolus. After one
hour or longer incubation the nucleolus became uniformly labeled. These observations indicate
that nucleolar RNA was produced at the periphery of the nucleolus, where the presence of DNA
could be demonstrated. It is probably not the nucleolus itself which pnoduces nucleolar RNA,
hut this DNA belonging to the chromosomal regions adjacent to the nucleolus. Experiments
with Actinomycin D showed that this DNA is functionally different from DNA in the rest of
chromosomes. When oocytes were incubated in H3-uridine in the presence of 2 pg/ml of Actinomycin
D, nucleoli remained unlabeled, while chromosomes became labeled nearly as strongly
as in the absence of the drug. At higher concentrations (IO pg/ml) Actinomycin D inhibited
both nucleolar and chromosomal RNA production. In conclusion it appears that the nucleoli serve
as intermediate storage or processing place for a certain kind of RNA, produced by particular
regions of chromosomes. The problem of transfer of chromosomal and nucleolar RNA into the
cytoplasm is now being studied by inhibiting new RNA formation with Actinomycin D.
ZAMENHOF, S., and ROSALIE DE GIOVANNI-DONNELLY, Columbia University, New York, N.Y.:
Heat-induced "coupled" mutations in B. subtilis-Among nine histidine- mutants obtained by
heating spores of the originally indole- strain 168 of B. subtilis, three have lost or altered this

ABSTRACTS 997
indole requirement simultaneously with acquisition of a histidine requirement (EPHRATI-ELIZUR,
SRINNASAN and ZAMENHOF, Proc. Natl. Acad. Sci. U.S. 47:56, 1961). A similar phenomenon
was found in Serratia (KAPLAN, 2. Vererb. 92:21, 1961).-In the present study, DNA’s from
two such strains (12 and 21) were used to transform the parent histidine+ indole- (nonlinked)
strain. In both cases the transformation to indole+ was accomplished, and with usual yield; this
suggests that in strains 12 and 21 the mutation to histidine- by itself did not suppress indole-,
but was “coupled” with another mutation, which either produced true repair of indole-, or else
an unrelated suppressor of indolc. The nature of this coupling is not clear; it suggests that
various “nonlinked” segments of DNA miolecule may not be mutationally independent.
No reversions to indole+ were observed among IO5 survivors of heating that did not mutate to
histidine-, indicating that the phenomenon is not due to the accidental coincidence of two independent
mutations.
ZIMMERING, S., Indiana University, Bloomington, Ind.: Temperature effects and segregation
in Drosophila mazes.-The sc4-sc8 chromosome lacks most of the proximal heterochromatin including
pairing sites (“collochores” of COOPER) and leads to an appreciable frequency of nullo-Xnullo-Y,
and a higher than normal frequency of XY, gametes from males carrying this X chromosome
and a Y chromosome (GERSHENSON 1940; SANDLER and BRAVER 1954). When males of
the composition ysc4-sc*/sc8-Y are raised at 26°C and 18°C from egg to eclosion, and then tested
at 26”C, the relative frequencies of the four kinds of gametes produced (from large scale experiments)
are, for those raised at 26”C, Xz48.2; Yz21.4; XYz2.0; 0=28.5, and for those raised
at 18”C, X=48.3; Y=42.2; XY=3.5; 0=6.0. The question arises: is the more normal transmission
of the Y chromosome from the experiments at the cooler temperature simply the result
of a greater opportunity for the Y chromosome to pair with and disjoin from the X chromosome
or is its more regular behavior independent of pairing. That the latter interpretation may be
correct is suggested by the finding that from Bar-Stone males of the composition XD,XPYL.YS
and not carrying a free Y chromosome, the component XPYL.YS, which is present as a univalent,
is recovered with virtually normal frequency when such males are raised at 18°C (and tested
at 26°C) despite an approximate 5045% loss of this component when they are raised at 26°C.
The possibility that the latter results are related to the so-called A effect (ZIMMERING 1960;
ZIMMERING and BARBOUR 1961) has been ruled out experimentally. (Supported by N.S,.F. grant
G13568.)