abstracts of papers presented at the 1962 meetings - Genetics

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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 tissues 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 encephalitis 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
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Page 3 and 4: ABSTRACTS 939 ARAKAKI, DAVID T., (I
Page 5 and 6: ABSTRACTS 941 BAND, H. T., and P. T
Page 7 and 8: ABSTRACTS 943 were the C57BL/6 pure
Page 9 and 10: ABSTRACTS 945 BROWN, RUSSELL V., an
Page 11 and 12: ABSTRACTS 94 7 development of corn
Page 13 and 14: ABSTRACTS 949 some closely linked t
Page 15 and 16: ABSTRACTS 95 1 An approach to this
Page 17 and 18: ABSTRACTS 953 Fox, A. S., I. L. MUN
Page 19 and 20: ABSTRACTS 955 mutants which form a
Page 21 and 22: ABSTRACTS 95 7 tion, respectively,
Page 23 and 24: ABSTRACTS 959 found in meiotic stag
Page 25 and 26: ABSTRACTS 961 cessive generations o
Page 27 and 28: ABSTRACTS 963 tances. For genes mor
Page 29 and 30: ABSTRACTS 965 environment interrela
Page 31 and 32: ABSTRACTS 967 dent maize inbred lin
Page 33 and 34: ABSTRACTS 969 procedure leaves much
Page 35 and 36: ABSTRACTS 971 63.1%. These results
Page 37 and 38: ABSTRACTS 973 hours to several week
Page 39 and 40: ABSTRACTS 975 to mutagen-induced li
Page 41: ABSTRACTS 977 the course of the exp
Page 45 and 46: ABSTRACTS 981 of the mutant alleles
Page 47 and 48: ABSTRACTS 983 enzyme synthesis.-Fiv
Page 49 and 50: ABSTRACTS 985 infected. Because vir
Page 51 and 52: ABSTRACTS 987 +/Su-V and Su-V/Su-V
Page 53 and 54: ABSTRACTS 989 sulfate concentration
Page 55 and 56: ABSTRACTS 991 XI1I.-These observati
Page 57 and 58: ABSTRACTS 993 body” is observed i
Page 59 and 60: ABSTRACTS 995 possibly third) mitot
Page 61: ABSTRACTS 997 indole requirement si

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