摘要:

AbstractOnly a single locus(Tpl)is known in the Drosophila melanogaster genome that leads to early lethality when present as a heterozygous duplication (three doses) or deficiency (one dose). We report the recovery of third instar larvae (and of occasional adults) carrying a duplication for the triplo‐lethal locus,Dp(Tpl).Karyotype analysis of the larvae showed that the individuals surviving were almost entirely 3X;2A metafemales. We examined the question of whether the entire X or a single X locus was a major factor permitting survival. X‐Y translocations were used to produce females hyperploid for different portions of the X and carryingDp(Tpl). Analysis of metaphase chromosomes by quinacrine fluorescence pattern indicates that the X chromosome region between 6D and 7DE must be present in an extra copy to enhance the survival ofTplduplication‐bearing females. Another type of experiment suggests that it is the region between 7C and 7DE which is esse

ISSN:0192-253X    

DOI:10.1002/dvg.1020020202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe development of sexual maturity has been studied in Tetrahymena hegewischi. Progeny lines do not typically change from immaturity to mating with all different mating types during a single test interval, but about 30% do mature abruptly. Some testers are more likely than others to participate in the earliest mating reactions of progeny lines which do not mature abruptly. Subcaryonidal vegetative pedigrees of 10 pairs from 4 crosses revealed considerable intrapair variation in the time, measured in fissions, of maturity. The average intrapair coefficient of variation was 20%. A nested ANOVA revealed significant genomic effects on the immaturity interval, but no significant cytoplasmic or caryonidal effects; 56% of the total variation was non‐genomic. Growth in different environments had highly significant effects on the immaturity interval. Subclones grown at 27°C with alternate day transfers took on the average 2 to 3 times as many fissions to mature as sister subclones grown at 27°C with daily transfers. Subclones grown at 18°C or 34°C and transferred on alternate days had intermediate maturation times. The greatest range in the immaturity interval among lines of the same genotype was from 34 to 143 fissions. The development of maturity in this species involves genetic control of timing, but the genetic differences are obscured by a large amount of intraclonal variation and sensitivity to the enviro

ISSN:0192-253X    

DOI:10.1002/dvg.1020020203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe antigens defined by conventional syngeneic antiserum against F9 embryonal carcinoma cells were localized on mature sperm using immunolabeling and scanning electron microscopy. Labeling patterns were compared for normal (+ / +) mice and mice bearing recessive t‐haplotypes. The results showed that antigens detected by intact anti‐F9 antiserum are expressed similarly in all genotypes, except for sperm from mice bearing thet12‐haplotype where the frequency of labeled cells was reduced. Labeling with the IgM fraction of anti‐F9 antiserum was lower on sperm from all t‐genotypes examined, with sperm from + /t12males showing the most marked reduction. In all cases, the labeling patterns were similar, and included a labeling of the whole sperm head with complete anti‐F9 antiserum and a restriction of the label to the postacrosomal region when the IgM fracti

ISSN:0192-253X    

DOI:10.1002/dvg.1020020204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractExperimental data on mating type determination in T. thermophila, collected by Nanney, Allen, and their collaborators over a period of 25 years, are reinterpreted in the light of our current understanding of macronuclear genetics. A strong case is developed supporting the idea that mating type determination involves the developmental alteration of somatic DNA that occurs regularly in developing macronuclei in conjugating pairs. A. testable DNA deletion/splicing model is developed that although based on a few simple, plausible assumptions, explains the observations remarkably well. The model is in (at least) superficial analogy to the mechanism that must be involved to explain the somatic differentiation and alteration of DNA sequences that ultimately constitute an expressed vertebrate immunoglobulin gene. Because of the genetic, biochemical, and micromanipulative versatility of Tetrahymena, it may well turn out to be a uniquely suitable microbial eukaryotic experimental system for the study of developmental alterations of somatic DNA.

ISSN:0192-253X    

DOI:10.1002/dvg.1020020205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

摘要:

AbstractThe ethyl methane sulfonate‐induced mutation,fs(1)1621, resides at 11.7 on the genetic map and within segment 4F1‐5A1 of the cytological map of the X chromosome. When homozygous,fs(1)1621renders females semisterile but has no effect on their viability; nor does it affect the viability or fertility of hemizygous males. Heterozygous females are fertile and have cytologically normal ovaries. The ovaries of homozygous females first produce normal oocytes, which, if fertilized, can develop into adult males or females. After this period, ovarian chambers containing only pseudonurse cells are formed, and finally mutant germaria produce only tumors. These contain hundreds to thousands of cells that appear to be derived from germarial cystocytes, because they occasionally form clones of interconnected cells and also can differentiate into endopolyploid pseudonurse cells. Raising the temperature speeds the rate at which tumors form; lowering it increases the probability of pseudonurse cell differentiation.Df(1)C159includesfs(1)1621. The pattern of ovarian chamber production is more temperature sensitive in hemizygous females than in homozygous ones. The morphology of hemizygous tumors and the number of dividing cells within them also differ from homozygotes. These observations support the hypothesis thatfs(1)1621is producing a product, that less is produced by one gene than by two, and that the product plays a role in the mitosis and cytokinesis of ovarian cystocy

ISSN:0192-253X    

DOI:10.1002/dvg.1020020206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020020207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020020201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1981

数据来源: WILEY