abstracts of papers presented at the 1962 meetings - Genetics

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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 direction 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 populations. (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 material. 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 aberrations 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 development of offsprings. (Supported in part by Atomic Energy Commission Research Contract AT (11-1)-38 and NIH Grant No. E-2753.)
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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: ABSTRACTS 975 to mutagen-induced li
Page 43 and 44: ABSTRACTS 9 79 RBDEI, G. P., Univer
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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