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Biomedical subjects

H Benes

Publications and source records attributed to H Benes.

26 records · Page 2Linked to original sources
PubMed1995

Characterization of an EcR/USP heterodimer target site that mediates ecdysone responsiveness of the Drosophila Lsp-2 gene.

The Larval serum protein-2 gene (Lsp-2) of Drosophila melanogaster is uniquely expressed in the fat body tissue from the beginning of the third instar to the end of adult life. Accumulation of the larval Lsp-2 transcript is enhanced by 20-hydroxyecdysone. To study the molecular basis for ecdysone regulated Lsp-2 activity, deletion mutants of the Lsp-2 5'-flanking region were constructed by fusion to either the Escherichia coli chloramphenicol acetyltransferase (CAT) gene or to an hsp70-lacZ hybrid gene encoding beta-galactosidase. Constructs transfected into Drosophila S2/M3 cells were shown to confer transient ecdysone inducibility on the reporter genes. A single functional ecdysone response element (EcRE) was localized at position -75 relative to the Lsp-2 transcription initiation site. In gel mobility shift assays using fat body nuclear extracts or nuclear receptors synthesized in vitro, a 27-bp sequence harboring the EcRE bound both the Drosophila ecdysone receptor and the Drosophila retinoid-X homologue, Ultraspiracle, in a cooperative manner. Competition experiments indicate that the affinity of the Lsp-2 EcRE for the ecdysone receptor complex is comparable to that of the canonical EcRE of the hsp27 gene and is at least 4-fold greater than that of Fbp1, another fat body-specific Drosophila gene. Our results suggest that structural features of this EcRE determine its ability to induce ecdysone responsiveness at a lower ligand concentration and may form the basis for differential hormone responsiveness within the fat body.

Animals↗
PubMed1990

Adult expression of the Drosophila Lsp-2 gene.

Previous work has demonstrated expression of the larval serum protein-2 gene, Lsp-2, uniquely during the late larval and pupal stages of development in Drosophila melanogaster. Here we report that the LSP-2 polypeptide accumulates in the hemolymph throughout adult life as well. Western blot analysis using an LSP-2 antiserum reveals notable differences in the molecular weight of the larval and adult polypeptides. Lsp-2 transcription results in a unique mRNA of 2.3 kb, exhibiting the same 5' end in both larvae and adults. However, adult Lsp-2 mRNa is only expressed at 1% of the high level detectable in late third-instar larvae. Whereas Lsp-2 mRNA accumulates uniformly in all fat body cells of third-instar larvae, over 80% of the adult Lsp-2 transcript is expressed in the adipose tissue of the head. These results suggest a differential regulation for expression of the Drosophila Lsp-2 gene in adults and larvae.

Animals↗
PubMed1990

Fat-body-specific expression of the Drosophila Lsp-2 gene.

The larval serum protein-2 gene (Lsp-2) of Drosophila melanogaster is expressed at a very high level in the fat body of third-instar larvae. Here we report that Lsp-2 transcription in adult flies produces a unique mRNA localized in the adult adipose tissue of the head in both sexes. To identify regulatory regions of this Drosophila gene, Lsp-2 5'-flanking DNA sequences were fused to the E. coli beta-galactosidase gene (lacZ). Transient expression of the hybrid gene in third-instar larvae indicates that 230 bp just upstream from the 'TATA box' of the Lsp-2 gene are sufficient for larval fat body-specific expression.

Animals↗
PubMed1989

Studies on the molecular-genetic basis of replicative senescence in Werner syndrome and normal fibroblasts.

Based on evidence that human diploid fibroblasts (HDF) from the Werner syndrome (WS) of premature aging might overexpress an inhibitor of DNA synthesis (IDS), we prepared a eukaryotic cDNA expression library from WS mRNA and tested it for IDS activity in a transient assay. Two of six WS cDNA pools tested gave IDS activity, then on plus/minus screening revealed several differentially expressed cDNA clones. By slot blot and Northern analysis, one cDNA clone was found to be overexpressed in WS and normal senescent HDF, but not in quiescent normal HDF, indicating that it is senescence-specific. Further studies are needed to clarify: a) whether this cDNA truly acts as an IDS; b) if so, whether it acts alone or in concert with other cDNAs; and c) whether it is involved in the degenerative and malignant sequelae of WS and normal aging.

Aging↗
PubMed1987

Nucleotide sequence of two repeating units of the 5S rRNA gene from the house cricket Acheta domesticus.

The 5S rRNA genes of the house cricket, Acheta domesticus, are contained within two basic repeating units measuring 3.0 and 2.1 kb, that have been cloned. Nucleotide sequence analysis was done on a 528-bp and a 541-bp EcoRI-HinfI DNA fragment from each cloned repeating unit which contains the 5S rRNA coding region. The nucleotide sequences of the 5S rRNA coding region from the two repeating units are identical.

Animals↗
PubMed1986

Hormonal and developmental specificities of transcription lie within a 1.5 kb region 5' to the ecdysone inducible Drosophila P1 gene.

P-element-mediated transformation was used to investigate 5' cis-acting regulatory sequences flanking the P1 gene of Drosophila melanogaster, which is selectively expressed in the fat body of late third instar larvae under the positive control of ecdysone. A hybrid gene was constructed by fusing a 1.5 kb DNA fragment directly adjacent to and including the first 25 transcribed bases of the P1 gene to the Escherichia coli xanthine guanine phosphoribosyltransferase (Ecogpt) gene itself linked at its 3' end to the SV40 t antigen splicing and polyadenylation sequences. Five transformed lines of D. melanogaster containing only one copy of the hybrid gene were established. In each of these lines the gpt sequence is transcribed with the same spatial, temporal and hormonal specificities as those of the P1 gene. This provides evidence that control elements essential for the ecdysone and developmentally regulated expression of P1 are located within a 1.5 kb region 5' to this gene.

Journal Article↗
PubMed1985

Analysis of genes for 5S rRNA from the cricket, Acheta domesticus: two classes of repeating units.

To examine the modulation of 5S rRNA gene activity during development in the cricket, Acheta domesticus, 5S X DNA was isolated from a lambda Charon 4 genomic library and characterized. Southern blot analysis of cloned A. domesticus genomic DNA revealed that restriction fragments of 3.0 and 2.1 kb represent two size classes of 5S X DNA repeating units; over 90% of the repeats measure 3.0 kb. Restriction analysis of two 5S X DNA clones suggests that the 2.1-kb repeats are not randomly interspersed within clusters of the larger 3.0-kb repeating units. Heteroduplex and restriction mapping of several clones indicate that the spacers of both repeating units account for their unusual length. The major difference between the two classes of repeats may lie in 0.9-kb spacer sequences to the 3.0-kb repeats.

Animals↗