摘要:

AbstractThe (ovarian tumor)otugene resides at 23.2 on the genetic map of the X chromosome and near 7F1 on the cytological map. Thisgerm line‐expressed locus behaves as if it encodes a gene product which is required during certain steps in the transformation of oogonia into functional oocytes. On the basis of their ovarian morphologies 17 ethyl methane sulfonate (EMS)‐induced mutants have been distributed among three developmental classes as follows: quiescent (eight), oncogenic (four), and differentiated (five). Theotu13andotu14alleles interact to yield fertile females, and many other heteroallelic combinations show partial complementation. Since many mutant alleles interact beneficially, the functional product of theotugene may be a multimer. We conclude, from an analysis of heteroallelic interactions and dosage effects, that the abnormal phenotypes observed are graded consequences of reduced levels of functional gene product and that the minimum concentration required for development increases as oogenesis proce

ISSN:0192-253X    

DOI:10.1002/dvg.1020070102

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe distribution of the soluble form of NADP+‐dependent isocitrate dehydrogenase (ICDH) was examined inDrosophila melanogasterimaginal discs. Development of the enzyme patterns and the specific transformations of the patterns by homoeotic mutants were studied. ICDH pattern formation was followed in eye‐antennal discs and wing discs from the late 2nd instar stage through 3rd instar and 8 hours into prepupal development. The patterns formed gradually in both disc types. The most interesting pattern developed in the eye portion of the eye‐antennal disc complex. ICDH distribution as well as staining intensity correlated well with differentiation of the ommatidia. The spatial distribution of ICDH within the discs was under genetic control. The patterns reflected the state of determination of the disc. When the presumptive tissue type was transformed via mutant homoeotic genes to different determinative states, the ICDH pattern likewise transformed to the pattern characteristic of the newly acquired stru

ISSN:0192-253X    

DOI:10.1002/dvg.1020070103

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe defective kernel (dek) mutants of maize are altered in both their embryo and endosperm development. Earlier studies have indicated that some of thedekmutants are unable to form shoot apical meristems or leaf primoirda. We have examined three embryo lethaldekmutants of this type,ptd*‐1130,cp*‐1418, andbno*‐747B, to obtain a developmental profile for each. Allelism tests show that these three mutants are not allelic. Embryos were examined in early, mid‐, and late kernel development as well as at kernel maturity by dissection and sectioning procedures and also at kernel maturity by scanning electron microscopy. All three mutants lag behind normal embryos in their rate of development. Embryos ofptd*‐1130reached the transition stage by early kernel development and progressed no further but underwent cell enlargement and necrosis during late kernel development. Embryos ofcp*‐1418reached an early coleoptilar stage by midkernel development. They subsequently increased in size but did not form any leaf primordia. At kernel maturity, they no longer had a shoot apical meristem but often had a well formed root meristem. They appeared to remain healthy and did not become necrotic. Embryos ofbno*747Breached the early coleoptilar stage by early kernel development but progressed no further. By kernel maturity, they had grown into masses of irregularly shaped embryonic tissue that no longer resembled any normal embryo stage but were not necrotic. None of these three mutants responded to attempts to support continued embryo development when cultured, but all three mutants formed callus on N6 and MS media supplemented with 2,4‐D. These results indicate that these mutants are all uniformly blocked at specific stages early in embryonic development, have different subsequent developmental fates, and represent three different genes performing unique functions that are essential for

ISSN:0192-253X    

DOI:10.1002/dvg.1020070104

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

年代:1986

数据来源: WILEY

摘要:

AbstractA single system is presented, where both genetic and epigenetic control of tumor induction can be studied at the same time. This system is offered by the amphidiploid tumorous hybridNicotiana glauca × N. langsdorffii, a nontumorous mutant of it and the nontumorous parent speciesN. glaucaandN. langsdorffii.The aim of the present paper is to compare long‐termin vitrocultures of tumorous (genetic and habituated), and nontumorous strains, through the characterization of their genomes according to several physico‐chemical parameters. The data reported show that both qualitative and quantitative differences in DNA complexity are correlated with the tumorous transformation. Particularly, a high degree of mismatching between the DNAs of the tumorous and nontumorous hybrids and the lack, in the second genotype (nontumorous), of three DNA peaks in Ag+−Cs2SO4analytical ultracentrifugation profile seem to support the hypothesis, suggested in a previous paper, of the presence, in the nontumorous mutant, of a gross chromosomal rearrangement, probably a deletion. Amplification and underreplication of specific sequences also seemed to be correlated with changes from the normal to the tumorous state, highly repetitive sequences being present in higher amounts in the normal strains and in the habituatedN. glaucathan in the case of the tumorous hybrid.Finally, DNA bound ion contents were found to be strikingly higher in tumorous than in nontumorous tissues. The results are discussed in the frame of the general hypothesis of high somatic genomic plasticity in

ISSN:0192-253X    

DOI:10.1002/dvg.1020070105

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

年代:1986

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020070101

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

年代:1986

数据来源: WILEY