摘要:

AbstractThe apterous (ap) mutant in Drosophila melanogaster exhibits phenotypes of wing deficiency, precocious adult death, and nonvitellogenic oocyte development. The latter phenotype previously has been shown to result from juvenile hormone (JH) deficiency in the adult stage. To explore the relationship between the hormone deficiency and the other phenotypes, the expression of each phenotype was measured in five alleles ofap(including a new, chemically‐induced allele,ap77f) as wing length, survival five days after eclosion, and initiation and progress of vitellogenic oocyte development. No correlation could be found between severity of wing phenotype and that of precocious adult death or nonvitellogenesis. However, the latter phenotypes were correlated in bothaphomozygotes and allelic heterozygotes, since adults that survive have wild‐type vitellogenesis, and those fated for precocious death fail to develop vitellogenic oocytes. These results indicate that no relationship exists between wing and JH deficiencies, but that precocious adult death is related to hormone deficiency — probably through pleiotropy, rather than through caus

ISSN:0192-253X    

DOI:10.1002/dvg.1020010302

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

年代:1979

数据来源: WILEY

摘要:

AbstractGenomic exclusion is an aberrant form of conjugation of Tetrahymena thermophila in which the genome of a defective conjugant is excluded from the genotype of the exconjugant progeny. This paper is concerned with the cytogenetic and nucleocytoplasmic events of genomic exclusion in senescent clones A*III and C*. In crosses between A*III or C* and strain B, functional, haploid gametic nuclei are formed only in the strain B cell. In some instances one of the gametic nuclei divides prior to transfer of the migratory gametic nucleus, and both products then undergo DNA synthesis. Two alternative cytogenetic pathways are followed after transfer of the migratory nucleus. In the first, the conjugants separate without further micronuclear divisions. This pathway was most common in A*III genomic exclusion. In exconjugants the former gametic nuclei undergo both DNA synthesis and (presumably) intranuclear separation of centromeres to restore micronuclear diploidy. The old macronucleus of each exconjugant is retained without autolysis. This class of exconjugant survives and contributes genes to future sexual progeny. In the second cytogenetic pathway the gametic nuclei divide and macronuclear anlagen are formed, as in normal conjugation. This pathway was more common in C* genomic exclusion. The initial DNA content of the anlagen ranges from haploid to diploid. Following two to three rounds of DNA synthesis, further macronuclear development ceases and the anlagen appear to undergo autolysis. The old macronucleus condenses and also undergoes autolysis, as in normal conjugation. Except for rare C* exconjugants, in which macronuclear development is completed, anlagen‐bearing genomic exclusion exconjugants die. Death may be caused by aneuploidy, errors in the timing or receptivity to signals for autolysis, or the inability of anlagen‐bearing exconjugants to feed. Anlagenbearing conjugants are frequently abnormal with respect to the number of anlagen and micronuclei. Most of the anomalies can be explained by postulating errors in the timing of both developmental signals and nuclear divisions. Rare conjugants in which gametic nuclei divide but do not give rise to macronuclear anlagen are also observed. In these instances, the old macronuclei condense and undergo autolysis. Destruction of the old macronucleus therefore is independent of the presence of macronuclear anlagen and requires cell pairing in order to be initia

ISSN:0192-253X    

DOI:10.1002/dvg.1020010303

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

年代:1979

数据来源: WILEY

摘要:

AbstractDeletions of gene sequences in chromosome 7 of the mouse are known to interfere with biochemical and cellular development differentiation with lethal effects in homozygotes. The presence of the corresponding wild‐type alleles in Cattanach's translocation (chromosomes 7 to X) is able to “rescue” potentially lethal females if they are made heterozygous for the translocation‐carrying X chromosome. This holds true for those chromosome 7 deletions with perinatally lethal effects, whereas “rescue” is not readily accomplished with the deletions that cause early embryonic lethality. Females homozygous for the relevant deletion sequences and heterozygous for the translocation‐carrying X chromosome are mosaics of two cell types: those in which the wild‐type alleles included in the translocated piece complement the depleted sequences, resulting in a normal cellular phenotype, and those with the ordinary X chromosome expressing the lethal phenotype. The developmental interactions between the two cell types and their role in the mechanisms responsible for survival of females homozygous for lethal deletions are discussed. The failure of “rescue” of embryonic lethals reflects as yet unknown temporal and functional aspects of X‐inactivatio

ISSN:0192-253X    

DOI:10.1002/dvg.1020010304

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

年代:1979

数据来源: WILEY

摘要:

AbstractDrosophila heteroneura and D differens are closely related, interfertile species of the Hawaiian picture‐winged group. They display marked qualitative and quantitative differences in the pattern of expression of alcohol dehydrogenase (ADH) and an aldehyde oxidase (AO‐1). These presumptive regulatory differences are revealed by comparisons of the relative levels of these enzymes in various tissues in larvae and adults. In hybrids produced between parents carrying different electrophoretic alleles at the structural loci for these two enzymes, each allele is expressed according to the developmental program characteristic of the parent from which it was derived. This result indicates control of the differences in pattern of expression by one or more cis‐acting sites associated with each structural locus. The distribution of activity among all the three forms of these dimeric enzymes produced in hybrids indicates that the pattern differences reflect differential accumulation of enzyme molecules, not altered catalytic properties. As expected, the regulatory differences segregate with the electrophoretic markers in backcr

ISSN:0192-253X    

DOI:10.1002/dvg.1020010305

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

年代:1979

数据来源: WILEY

摘要:

AbstractSeven mutations affecting β‐glucosidase activity in Dictyostelium discoideum were found to be non‐complementing, recessive to the wild‐type allele, and to occur in the gene locus, gluA. This gene, which is likely to be the structural gene for β‐glucosidase, since a mutation in it gives rise to thermolabile activity and other mutations in it result in no measurable activity, was mapped to linkage group VI. The expression of the β‐glucosidase gene is regulated such that the enzyme is synthesized during the growth phase and during culmination, but not during the first 18 hours following the initiation of development. If expression of the structural gene required the function of a positive regulatory protein coded for by a gene as mutable as the gluA gene, there was greater than 99% chance one of the mutations of this series would have affected the regulatory locus. The absence of a second complementing locus for β‐glucosidase suggests that this enzyme is regulated

ISSN:0192-253X    

DOI:10.1002/dvg.1020010306

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

年代:1979

数据来源: WILEY

摘要:

AbstractHomozygous Drosophila females bearing the ocelliless mutation are sterile and produce oocytes with abnormal chorions. It has been possible to determine in which tissues these defects reside by generating ovarian chimeras. Pole cells from ocelliless female embryos can give rise to functional oocytes surrounded by normal chorions when placed in a wild‐type environment. Conversely, when wild‐type pole cells are placed in homozygous ocelliless females, the oocytes that form from them have abnormal chorions and never give rise to progeny. Thus the chorion defect and sterility of the ocelliless mutation are not germ‐line autonomous. Homozygous ocelliless ovaries will attach to the uterus when placed in a wild‐type third instar larva, but few eggs are ever laid, and the chorions of stage 14 oocytes remain ocelliless in morphology. Wild‐type ovaries continue to produce oocytes with normal chorion morphology when placed into ocelliless hosts, indicating that the ocelliless chorion defect is ovary autonomous. Thus the chorion defect of the ocelliless mutation resides in the ovarian somatic tissue, presumably the folli

ISSN:0192-253X    

DOI:10.1002/dvg.1020010307

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

年代:1979

数据来源: WILEY

摘要:

AbstractA protein which has been shown to inhibit catalase in vitro appears to vary inversely with catalase activity in the maize scutellum during early sporophytic development when assayed using a catalase inhibition assay. This result suggested that the inhibitor protein may play a direct role in regulating catalase activity during this time period.Four experimental approaches were used to evaluate this putative regulatory role, including immunological quantitation of individual catalase isozymes during germination using rocket immunoelectrophoresis, perturbation of normal catalase expression with hydrogen peroxide or allylisopropylacetamide (AIA), examination of a mutant line with an altered catalase developmental program, and direct radioimmunoassay of the inhibitor protein during germination. The results of these experiments indicate that the quantitative changes in catalase activity during development are not mainly due to changes in the expression of the catalase inhibitor. Other possible roles of this protein in catalase regulation are discussed.

ISSN:0192-253X    

DOI:10.1002/dvg.1020010308

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

年代:1979

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020010301

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

年代:1979

数据来源: WILEY