abstracts of papers presented at the 1962 meetings - Genetics

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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 pantothenate, 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
Page 1 and 2: ABSTRACTS OF PAPERS PRESENTED AT TH
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: ABSTRACTS 953 Fox, A. S., I. L. MUN
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 and 42: ABSTRACTS 977 the course of the exp
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

abstracts of papers presented at the 1962 meetings - Genetics

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