摘要:

AbstractThis review summarizes information on accumulation profiles of individual gene transcripts in preimplantation development. Most of the information is from the mouse, but some data from other species are reviewed as well. The principal finding is that the transcription of most genes is not temporally linked with any of the three morphogenetic transitions (compaction, cavitation, and blastocoel expansion) that characterize this period. Most genes that are expressed during pre‐implantation development of the mouse are already being transcribed in the 4‐cell stage, and some clearly begin as early as the 2‐cell stage. Once activated, a gene continues to be transcribed at least into the blastocyst stage, resulting in continuous mRNA accumulation. Thus the pattern of gene transcription established at the time of genomic activation in the 2‐cell stage is perpetuated into the blastocyst, with a few additions along the way. This information is interpreted in light of previous findings concerning the sensitivity of morphogenetic transitions to inhibition of gene expression. The lack of a clear relationship between the timing of expression of most genes and the schedule of morphogenesis leads one to conclude that temporal regulation is imposed downstream of transcription and translation. This conclusion is substantiated by a consideration of factors controlling the events of compaction. © 1992 Wiley

ISSN:0192-253X    

DOI:10.1002/dvg.1020130502

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

年代:1992

数据来源: WILEY

摘要:

Abstractpolyhomeoticis a member of a group of genes, the Pc‐group responsible for the maintenance of gene expression during development. In particular, the Pc‐group of genes is involved in the correct expression of homeotic genes of thebithoraxandAntennapediacomplexes.Molecular analysis reveals that the Pc‐group genes function relatively late in development, once homeotic gene expression has been correctly initiated. This initiation of homeotic gene expression depends on interaction between genes in the segmentation gene hierarchy, the gap and pair‐rule genes.The in situ analysis presented here indicates thatpolyhomeotictranscripts are expressed in a spatially restricted fashion early in development. This blastoderm expression is under the control of genes in the segmentation hierarchy. Given these results, and the role ofpolyhomeoticin the correct maintenance of homeotic gene expression, I propose that polyhome otic expression may relay the initiation of homeotic gene expression with other mechanisms involved in the maintenance of this expression, involving the otherPc‐group genes. © 1992 Wiley

ISSN:0192-253X    

DOI:10.1002/dvg.1020130503

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

年代:1992

数据来源: WILEY

摘要:

AbstractDrosophilaimaginal discs are induced by the steroid hormone 20‐hydroxy‐ecdysone to initiate morphogenesis leading to formation of the adult appendages and thoracic epidermis at the end of the third larval instar. Ecdysone‐dependent transcriptional activation of a set of genes that encode imaginal disc transcripts found on membrane‐bound polysomes precedes and may be responsible for some aspects of the cellular changes that mediate epithelial morpho‐genesis in this system. A 1.35 kb transcript from one of these genes,IMP‐L1, is first observed in vivo at or just prior to pupariation, as ecdysone titers are peaking and beginning to decline. Expression is initiated in proximal areas of the antennal disc, later spreading to a more widespread but nonuniform distribution throughout other thoracic imaginal discs.IMP‐L1is not, however, expressed in other ecdysone target tissues such as salivary glands or fat body. TheIMP‐L1gene encodes a novel protein product containing a signal peptide, a possible transmembrane domain, two highly charged domains and a proline rich C‐terminal domain. We suggest that the delayed timing of expression of this secondary response gene is necessary for proper ordering of cellular events associated with disc morphogenesis. © 19

ISSN:0192-253X    

DOI:10.1002/dvg.1020130504

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

年代:1992

数据来源: WILEY

摘要:

AbstractWe have isolated and characterized genomic DNA clones for the human and chicken homologues of the mouseEn‐1andEn‐2genes and determined the genomic structure and predicted protein sequences of bothEngenes in all three species. Comparison of these vertebrateEnsequences with theXenopus En‐2(Hemmati‐Brivanlouet al., 1991) and invertebrateengrailed‐like genes showed that the two previously identified highly conserved regions within theEnprotein [reviewed in Joyner and Hanks, 1991] can be divided into five distinct subregions, designated EH1 to EH5. Sequences 5′ and 3′ to the predicted coding regions of the vertebrateEngenes were also analyzed in an attempt to identify cis‐acting DNA sequences important for the regulation ofEngene expression. Considerable sequence similarity was found between the mouse and human homologues both within the putative 5′ and 3′ untranslated as well as 5′ flanking regions. Between the mouse andXenopus En‐2genes, shorter stretches of sequence similarity were found within the 3′ untranslated region. The 5′ untranslated regions of the mouse, chicken andXenopus En‐2genes, however, showed no similarly conserved stretches. In a preliminary analysis of the expression pattern of the humanEngenes,En‐2protein and RNA were detected in the embryonic and adult cerebellum respectively and not in other tissues tested. These patterns are analogous to those seen in other vertebrates. Taken together these results further strengthen the suggestion thatEngene function and regulation has been conserved throughout vertebrate evolution and along with the five highly conserved regions within theEnprotein, raise an interesting question about the presence of conserved genetic p

ISSN:0192-253X    

DOI:10.1002/dvg.1020130505

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

年代:1992

数据来源: WILEY

摘要:

AbstractA female‐sterile mutation(fs(2) PM11‐19)was recovered in a screen for P‐M hybrid dysgenesis induced mutations uncovered by a deletion of region 21B and was identified as an allele of the gene encoding theDrosophilaglutamine synthetase I (GSI) mitochondrial isozyme.Molecular analysis has shown thatfs(2)PM11‐19contains a 5 kb insert within 500 bp upstream of the transcriptional start site of thegsIgene. Mutant flies have extremely low levels ofgsltranscription and GSI activity. A pre‐existing deficiency(Df(2L) netpm1) with a breakpoint near the transcription start site was also found to be a female‐sterile allele ofgsl.All eggs laid byPM11‐19homozygous females, as well as by females heterozygous for this mutation and a deletion or any of several recessive lethal alleles of thegslgene, fail to hatch. We conclude that an adequate level of maternally supplied GSI activity is necessary in the early stages ofDrosophilaembryonic development. © 1992 W

ISSN:0192-253X    

DOI:10.1002/dvg.1020130506

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

年代:1992

数据来源: WILEY

摘要:

AbstractAn efficient method for generating embryonic mosaics using a yeast site‐specific recombinase (FLP), under the control of a heat shock promoter, is described.FLP‐recombinase can promote mitotic exchange between homologous chromosomes that containFRT(FLPRecombination Target) sequences. To demonstrate the efficiency ofFLP‐recombinase to generate embryonic mosaics, clones of the recessive and cell autonomous mutationarmadillo(arm), detected by their ability to differentiate ectopic denticles in the naked cuticle of each abdominal segment, have been induced. We have analyzed the parameters ofFLP‐recombinase induced embryonic mitotic recombination and have demonstrated that clones can be efficiently induced during the postblastoderm mitotic divisions. We discuss applications of this technique for the analyses of the roles of various mutations during embryonic patterning. © 1992 Wiley

ISSN:0192-253X    

DOI:10.1002/dvg.1020130507

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

年代:1992

数据来源: WILEY

摘要:

AbstractThree characteristics of standardMutatorlines reflect developmental regulation: new mutants usually involve single gametes, somatic excision is restricted to terminal cell divisions during tissue development, and germinal excision is rare. By selection for earlier (larger) somatic sectors in the aleurone, aMutatorline was identified that exhibits a dramatic elevation in somatic excision frequency during the first three nuclear divisions of the endosperm and more than a 10‐fold increase in germinal reversion from thebzl::Mulreporter gene. The programming of early sectoring is dominant in crosses withMutatorlines containing diverse reporter alleles. Germinal reversion is biased 5‐ to 10‐fold for events through the pollen compared to the ear. The timing of germinal excision in the tassel is late because somatic excision sectors in the anthers are small; however, 98% of the germinal revertants are concordant. These observations indicate that in the early sectoring lineMuexcision usually occurs before the mitotic divisions that separate gametic nuclei and may be restricted to the early stages of microsporogenesis. © 1992 Wiley‐L

ISSN:0192-253X    

DOI:10.1002/dvg.1020130508

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

年代:1992

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020130501

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

年代:1992

数据来源: WILEY