ISSN:0192-253X    

DOI:10.1002/dvg.1020040402

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

年代:1983

数据来源: WILEY

摘要:

AbstractGenetic analysis has suggested that neurogenesis in Dmelanogasteris under the control of a small number of genes. We have initiated a molecular study of the genes involved in this developmental event and started our analysis with theNotchlocus, which is one of the best characterized loci in Dmelanogasterin terms of its genetic structure and developmental effects. In this paper we report on the molecular characterization of theNotchlocus.We describe the molecular cloning ofNotchand present evidence that the entire locus is defined by approximately 40 kb of genomic DNA. The transcriptional activity of these sequences during development has been examined and the results indicate that an approximately 10.5‐kb‐long poly A+ RNA is essential for wild typeNotchactivity. Mapping of this RNA within the physical map ofNotchindicates that it is the processed product of an approximately 40‐kb primary transcription unit spanning the entireNotchlocus. More detailed analysis of the 10.5 kb RNA localizes several exons and identifies a small repetitive sequence that seems to be present in the matureNotchtranscript. Structural details of a selected number ofNotchlocus mutations are presented and discussed. Preliminary data on the molecular structure ofNotch‐homologous DNA sequences in closely related species are also pr

ISSN:0192-253X    

DOI:10.1002/dvg.1020040403

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe four small heat shock protein genes of Drosophila are tightly linked at the level of DNA, and are coordinately regulated. In cultured cell lines their expression is induced by high temprature shock and by physiological doses of ecdysterone.In vivo, small heat shock gene expression is developmentally regulated. Using recombinant DNA clones we have characterized and compared small hsp gene induction in response to the two independent stimuli.

ISSN:0192-253X    

DOI:10.1002/dvg.1020040404

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe manufacture of mammalian chimeras by aggregating embryos of different genetic constitutions makes possible the study of the genetic control of cellular interactions during embryonic development. Several different chimeric combinations have been made to study the role of the sex‐reversed mutation in gonadogenesis and in gametogenesis. Sex reversed directs the gonad to become a testis and thus renders a SxrXX mouse sterile since gonocytes with two X chromosomes cannot complete gametogenesis in a testis. However, SxrXX gonocytes in the ovary of a female chimera become normal oocytes. The competitive interactions of genetically different melanoblasts in populating hair follicles and of primordial germ cells in populating the gonad have been revealed in chimeras. Chimeras have also been used to rescue inviable teraploid embryos and to permit teteraploid cells to display their differentiative capacities in normal tissue environments. We conclude that the genotype affects the capacity of cells to elaborate and to respond to inductive stimuli at each step in differentiation. The fine tuning of cellular interactions becomes apparent in chimeras made from embryos of different genotyp

ISSN:0192-253X    

DOI:10.1002/dvg.1020040405

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe catalase (H2O2:H2O2oxidoreductase; E.C.1.11.1.6; CAT) gene‐enzyme system in Zea mays L (maize) represents an ideal model for studying the molecular basis of developmental gene regulation in higher eukaryotes. This system comprises a family of structural genes that are highly regulated, both temporally and spatially, during maize development.In maize, there are four distinct forms (isozymes) of catalase that are readily discernible by convetional separation procedures. Three of the catalases have been studied in detail from a genetic and biochemical viewpoint. The catalases CAT‐1, CAT‐2, and CAT‐3 are encoded by the distinct, unlinked genesCat1, Cat2, andCat3, respectively. Each of the structural genes is highly regulated both spatially and temporally in its expression.Cat1is expressed primarily in the endosperm, aleurone, pericarp, and scutellum of developing kernels, and in the root, shoot, and scutellum of very young seedlings.Cat2is expressed primarily in the scutellum and leaf during postgerminative sporophytic development.Cat3is expressed, for the most part, in the shoot and pericarp of young seedlings.A number of regulatory variants have been recovered that affect the developmental program of expression of the catalases. Analysis of one variant allowed for the identification of a temporal regulatory gene (Car1) that specifically alters the developmental program of theCat2structural gene by acting to regulate the rate of CAT‐2 protein synthesis.Cat1has been mapped on chromosome 1S, 37 map units (m.u.) from theCat2structural gene. Another variant line has been isolated which lacks expression of theCat2gene in its tissues at all stages of development. Isolated polysomes from this line (A16) were translatedin vitro, and the products were immunoprecipitated with CAT‐2‐specific antibodies. No CAT‐2 was detectable in the A16 labeled immunoprecipitates, whereas CAT‐2 was readily detected in the normal line, W64A, under similar conditions.The temporal and spatial expression of theCatstructural genes is not only influenced by genetic factors (as above), but is also responsive to exogenously applied environmental signals: light, hormones, and temperature. The mechanisms by which such signals specifically affect CAT‐2 expressio

ISSN:0192-253X    

DOI:10.1002/dvg.1020040406

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe gene coding for alcohol dehydrogenase (Adh) in Drosophila melanogaster maps to 2:50.1 on chromosome arm 2L. It is expressed in both larvae and adults, coding for an abundant enzyme that plays a role in the detoxification of primary and secondary alcohols. In larvae the gene is most abundantly expressed in the fat body and gut. We have recently shown [49] that the majorAdhtranscripts differ in larvae and adults, the major adult transcript being initiated from a promotor several hundred pairs 5′ to the promotor from which the major larval transcript is initiated. However the coding region of the “larval and adult” mRNA are identical. We discuss recent studies of the transcriptional organizationAdhand compare the structure of this gene in D. melanogaster with that in other species of Drosophila. The entireAdhgene and its surrounds has been sequenced from four species of Drosophila [45,48]. This data has been used not only for the study of phylogenetic relationships, but also of the types of sequence variation seen between species. The constraints on mutational change, especially with respect to codons, will be disc

ISSN:0192-253X    

DOI:10.1002/dvg.1020040407

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

年代:1983

数据来源: WILEY

摘要:

AbstractA method is described for the experimental determination of the secondary structure of RNA using enzymatic cleavage data coupled with computer analysis. The structure‐specific enzymes S1 nuclease and cobra venom ribonuclease are used to locate nonpaired and basepaired nucleotides, respectively. Computer techniques that utilize the enzymatic susceptibility information to generate a minimum free‐energy structure are used to obtain secondary structure models. A second method, using acrylamide‐agarose gel electrophoresis, is described for the determination of the relative protein synthesis initiation rates of endlabeled eukaryotic mRNAs. These methods are applied to the rabbit globin mRNAs as an example of a general approach for relating mRNA structure and function. A discussion of the role of messenger RNA structure in the regulation of translation is included with an emphasis on studies of develo

ISSN:0192-253X    

DOI:10.1002/dvg.1020040408

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

年代:1983

数据来源: WILEY

摘要:

AbstractA 315 kb walk in the genetically well characterizedrosyregion of theDrosophilachromosomes permits a molecular analysis of chromosome organization. Polytene chromosome bands in this region range from less than 7 kb to about 160 kb and the level of DNA replication is constant within bands and among bands and interbands. A good numerical and topographical correspondence is found between chromomeric units and genetic units.

ISSN:0192-253X    

DOI:10.1002/dvg.1020040409

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

年代:1983

数据来源: WILEY

摘要:

AbstractA combination of technical advances (most notably heterologous cell fusion, high resolution G‐banding, and molecular cloning) has contributed to an accelerated advance in genetic analysis in mammals. The present human genetic map contains over 400 gene assignments and the map is growing rapidly as each new molecular clone or immunological reagent is developed. In our laboratory, we have developed a panel of rodent X human somatic cell hybrids that have been utilized in chromosome assignment of several classes of genes including oncogenes (ras, raf) and endogenous human retroviral sequences (ERVL, 2, etc). Using similar techniques, a biochemical genetic map of the domestic cat has been derived. The cat has 19 chromosome pairs and, to date, 40 genes have been mapped to 16 linkage or syntenic groups. Comparison of linkage relationships between homologous enzymes has revealed a striking conversation of chromosomal linkage association between cat and man. A comparison of syntenically homologous, highly extended high resoultion G‐banded chromosomes between the two mammalian families revealed that 20–25%, by length, of the human karyotype can be precisely aligned (chromomere to chromomere) between cats and man despite the evolutionary divergence of the species nearly 80 million years ago.Moderately repetitive families of retrovirus‐related DNAs exist within the feline and the human genomes. We have isolated molecular clones of several members of the feline RD‐114 retrovirus family from a genomic library of normal cat cellular DNA. The endogenous sequences analyzed were similar to each other in that they were colinear with RD‐114 proviral DNA, were bounded by long terminal redundancies, and conserved many restriction sites in thegagandpolregions. Several sequences were apparently deleted, relative to the previously characterized inducible RD‐114 genome. Theenvregions of a number of endogenous RD‐114 sequences examined were substantially deleted or diverged; a subset of these sequences contained information at the position of theenvregion that was not homologous to inducible RD‐114. The RD‐114 virogenes were dispersed to several cat chrosomes that were localized using a panel of rodent x cat somatic cell hybrids. A comparison of the genetic properties of endogenous human retroviral sequences revealed several similarities between the human and feline status of endo

ISSN:0192-253X    

DOI:10.1002/dvg.1020040410

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

年代:1983

数据来源: WILEY

摘要:

AbstractReproductive behavior in Drosophila involves a complex series of actions which is perturbed by many different kinds of mutations. Some of the most interesting courtship variants are those originally isolated with respect to disruptions of general learning and memory. Several types of genetically abnormal males have their “conditioned courtship” blocked or attenuated by the learning and memory mutations, some of which, in turn, are known to cause abnormal levels of specific monoamines or cyclic nucleotides. Recent studies of the defective courtship performed by the conditioning mutants involve “mosaic focusing” of the neural tissues affected by the behavioral/biochemical mutations. These experiments address the question of whether there are localized influences of the relevant genetic loci in their control of conditioned courtship, in spite of the fact that the protein products of the genes have a broad tissue distribution. Female responses to courting Drosophila males can also be dependent on the former's prior experiences. This pertains to enhancing aftereffects of prestimulation by the courtship song that is produced by a male; and the same learning and memory mutations, expressed in females, impinge on the normal aftereffects. One element of acoustical communication in courtship is a rhythmic oscillation in a particular component of the song. This short‐term behavioral rhythm is altered in males expressing circadian rhythm mutations. To investigate the neural and cellular mechanisms by which these genes act, a mosaic analysis has been initiated on the ganglia affected by a clock mutation in its disruption of the courtship rhythm and of circadian cycles. A molecular isolation and identification of the normal form of this genecalledperiod—has also begun, in order to probe the locus's structure and function in detail. Such an investigation will include a comparison of the mosaic results with a direct determination of the various tissues in which the gene's product is expressed. In addition, interspecific transfers of the purifiedperiodgene will augment the current studies of species‐specific features of the rhythmic co

ISSN:0192-253X    

DOI:10.1002/dvg.1020040411

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

年代:1983

数据来源: WILEY