摘要:

AbstractWe report the isolation of two retinoic acid receptor isoforms (RARγ), which differ only in the 5′ untranslated and putative N‐terminus A regions. The two isoforms appear to serve as early markers for the presumptive neural axis; however, their expression patterns differ.RARγ2, 1is first expressed at gastrulation at the dorsal lip and subsequently along the presumptive neural axis.RARγ2.2represents the full‐length sequence of a receptor cDNA already partially characterized and present as a maternal transcript [Ellinger‐Ziegelbauer and Dreyer (1991); Genes Dev 5:94‐104, (1993): Mech Dev 41:31‐46; Pfeffer and DeRobertis, (1994) Mech Dev: 45:147‐153]. UnlikeRARγ2.2, the2.1variant is not expressed either in pre‐somitic mesoderm or notochord.RARγ2.1is strongly expressed in branchial arches and to a lesser extent in the neural floor plate. The two isoforms also exhibit differential sensitivity to retinoic acid. Constitutive expression ofRARγ2.2following neurulation appears to be depressed by treatment with retinoic acid, but domains of highest expression, namely, the head and tail, remain relatively unaffected, as do patterns of expression prior to late neurulation. By contrast,RARγ2.1is not transcribed in retinoid‐inhibited structures. Using microinjection techniques, we show that changes ofRARγ2.1expression in presumptive head structures occur as an early and local consequence of retinoic acid administration. SinceRARγ2.1expression is inhibited by retinoic acid, we tested to see if other treatments that perturb axis formation had any effect. Surprisingly, UV irradiation did not suppress expression of theRARγ2.1transcript, suggesting that its inhibition by retinoic acid is not due solely to inhibition of anterior neural development. These experiments demonstrate a new subdivision of isoforms that undergo differential expression during development and that exhibit differential sensitivity to retinoic acid and to UV. This sensitivity and the presence of this isoform variant in regions that are known to exhibit polarizing activity strengthen the hypothesis that these receptors play a primar

ISSN:0192-253X    

DOI:10.1002/dvg.1020170402

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

年代:1995

数据来源: WILEY

摘要:

AbstractDevelopmental expression of the heat shock inducible non‐protein codinghsromegagene in several larval and adult tissues ofDrosophila melanogasterwas examined byin situhybridization to transcripts in intact organs and by X‐gal staining in the germline transformants carrying thelacZreporter gene under the control ofhsromegapromoter. This gene is expressed in a specific spatial pattern in all the larval and adult tissue types examined; however, its transcripts were specifically absent in certain gonadal cell types like the male as well as female gonial cells and in follicle cells and oocytes in ovary. All polytenised tissues like the prothoracic and salivary glands, certain regions of larval gut and the Malpighian tubules showed a greater abundance ofhsr‐omegatranscripts with a strong hybridization in nuclei. Our results with promoter deletion variant germline transformants suggest that a region between –346bp to –844bp upstream contains major regulatory element/s for developmental expression of this gene in most of the larval and adult tissues examined; however, this region is not sufficient for its normal expression in male and female reproductive systems. An analysis of the base sequence of thehsr‐omegapromoter (upto –844bp) reveals putative ecdysone receptor element half‐sites and two GAGA factor binding sites which may be involved in its developmental expression and its ready inducibility. The widespread expression in most tissue types and the known lethality associated with its homozygous deletion, suggest that the variety of non‐protein coding transcripts of thehsromegagene have vital “house

ISSN:0192-253X    

DOI:10.1002/dvg.1020170403

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

年代:1995

数据来源: WILEY

摘要:

AbstractLiver‐specific expression of the rat aldolase B (AldB) gene is conferred by proximal promoter region (‐200 bp to + 1 bp), which is centered on an origin region of DNA replication. Transcriptional activation of the gene in the liver occurs during the late one‐third of fetal stage. To know the mechanism involved in such activation, we studied developmental changes in chromatin structure and in the extent of CpG methylation in the promoter/origin region of the gene. At an early fetal stage, when the AldB gene in the liver is not yet activated, the gene chromatin had two DNase l‐hypersensitive sites in the promoter region. One corresponded to that typical of AldB‐expressing cells in the adult. The other, located ∼200 bp upstream of the above site, disappeared as the activation of transcription started. A CpG dinucleotide in the promoter/origin region was heavily methylated at an early stage of gestation, but progressively demethylated as the liver develops. This CpG site is located at the center of an important binding site for a transcription factor. These changes occurred early in the fetal stage, prior to the gene activation, and were thus thought to be associated with differentiation of the liver cell or with cessation of cell pr

ISSN:0192-253X    

DOI:10.1002/dvg.1020170404

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

年代:1995

数据来源: WILEY

摘要:

AbstractDegenerate oligonucleotides were designed on the basis of conserved amino acid sequences in the DNA and ligand‐binding regions of the members of the steroid hormone receptor superfamily. Using these oligonucleotides in RNA‐PCR, a cDNA fragment was isolated from the spruce budworm,Choristoneura fumiferana.Comparison of the deduced amino acid sequence of this cDNA fragment with the members of the steroid hormone receptor superfamily suggested that this PCR fragment is a region of the ecdysone receptor fromC. fumiferana.Using this cDNA fragment as a probe, 10 clones were isolated from a cDNA library that was constructed using the RNA from 4‐ and 5‐day old embryos ofC. fumiferana.Two cDNA clones (1.3 and 3 kb) that overlap and show amino acid identity withDrosophila melanogasterecdysone receptor B‐1 isoform (DmEcR) were characterized and sequenced. The longest open reading frame had 539 codons and covered the complete EcR coding region. The deduced amino acid sequence of this open reading frame had all five of the regions typical for a steroid hormone nuclear receptor. The C domain or DNA binding region showed the highest identity with EcR proteins fromD. melanogaster, Chironomus tentans, Aedes aegypti, Manduca sextaandBombyx mori.The A/B region, D domain or hinge region, E domain, or ligand binding region also showed significant amino acid similarity with the EcR proteins from the five insects mentioned above. The C.fumiferanaecdysteroid receptor (CfEcR) cDNA probe detected a 6.0‐kb mRNA that was present throughout the development ofC. fumiferana.The CfEcR mRNA increases in abundance at the time of the ecdysteroid peak during the molting phase in the embryonic, larval and pupal stages but remains low during the intermolt period. In the 6th instar larvae, the 6‐kb CfEcR mRNA was detected in the epidermis, fat body, and midgut and maximum expression was observed during the prepupal peak of ecdysteroids in the hemolymph. CfEcR mRNA was induced in ecdysone treated CF‐203 cells as well as in the epidermis and midgut of larvae that were fed the nonsteroidal ecdysteroid agonist, RH‐5992. The induction occurred within an hour and reached maximum levels around 3 hr, after which it decreased to the basal level by 6 hr. In vitro transcription and translation of the CfEcR cDNA yielded a 67‐Kda protein that bound to the ecdysone response element (EcRE) as a heterodimer, along with theu

ISSN:0192-253X    

DOI:10.1002/dvg.1020170405

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn the present study we have characterized the synthesis of members of the HSP30 family duringXenopus laevisdevelopment using a polyclonal antipeptide antibody derived from the carboxyl end of HSP30C. Two‐dimensional PAGE/immunoblot analysis was unable to detect any heat‐inducible small HSPs in cleavage, blastula, gastrula, or neurula stage embryos. However, heat‐inducible accumulation of a single protein was first detectable in early tailbud embryos with an additional 5 HSPs at the late tailbud stage and a total of 13 small HSPs at the early tadpole stage. In theXenopusA6 kidney epithelial cell line, a total of eight heat‐inducible small HSPs were detected by this antibody. Comparison of the pattern of protein synthesis in embryos and somatic cells revealed a number of common and unique heat inducible proteins inXenopusembryos and cultured kidney epithelial cells. To specifically identify the protein product of the HSP30C gene, we made a chimeric gene construct with theXenopusHSP30C coding sequence under the control of a constitutive promoter. This construct was microinjected into fertilized eggs and resulted in the premature and constitutive synthesis of the HSP30C protein in gastrula stage embryos. Through a series of mixing experiments, we were able to specifically identify the protein encoded by the HSP30C gene in embryos and somatic cells and to conclude that HSP30C synthesis was first heat‐inducible at the early tailbud stage of development. The differential pattern of heat‐inducible accumulation of members of the HSP30 family duringXenopusdevelopment suggests that these proteins may have distinct functions at specific embryonic stages during a stre

ISSN:0192-253X    

DOI:10.1002/dvg.1020170406

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe have performed a comparative analysis of the effects of age of reproduction on the biochemical (protein, lipid, and glycogen content) and stress resistance (ability to survive starvation, desiccation, and exogenous paraquat) parameters on 10 sister lines of five differentDrosophilastrains. Four pairs of these sister lines were selected under different regimens for either early or delayed reproduction; the fifth pair was maintained in a nonselected state and served as the baseline strain to which all others were compared. It is generally accepted that the early regimens give rise to short‐lived phenotypes, whereas the delayed regimens give rise to long‐lived phenotypes. Our results suggest that a mechanism involving lipid and starvation resistance is not operative in our long‐lived strains. In addition, a mechanism involving glycogen content and desiccation resistance is only weakly supported. Finally, there is strong support for a mechanism that gives rise to enhanced paraquat resistance and therefore may involve regulatory changes in the pattern of ADS gene expression. In addition, the 15‐day early age at reproduction regimen (M type) shows qualitatively similar responses to that of the late age at reproduction regimen (L type). These results suggest that correlations between biochemical traits and longevity must be interpreted with caution. We discuss possible reasons for these results, including the possibility of multiple mechanisms, each leading to a different extended longevity ph

ISSN:0192-253X    

DOI:10.1002/dvg.1020170407

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

年代:1995

数据来源: WILEY

摘要:

AbstractThis paper analyzes the interaction between resistance to free radicals, development under starvation conditions, sex, and its consequences to the lifespan ofDrosophila mela‐nogasterpopulations selected for developmental time and longevity. Our data suggest that the interaction between these physiological and environmental parameters is modulated largely by the pre‐imaginal developmental time, since the response to selection for longevity extremes depends strongly on the previous selection for developmental time extre

ISSN:0192-253X    

DOI:10.1002/dvg.1020170408

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

年代:1995

数据来源: WILEY

ISSN:0192-253X    

DOI:10.1002/dvg.1020170401

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

年代:1995

数据来源: WILEY