title: RNA metabolism in situ at the 93D heat shock locus in polytene nuclei of Drosophila melanogaster after various treatments.
abstract: Quantitative in situ hybridization to RNA on polytene chromosome spreads, using the 93D exon-, intron- and repeat-specific 35S-labeled antisense RNA probes, revealed treatment- (heat shock, benzamide, colchicine, heat shock followed by benzamide and heat shock in the presence of colchicine) specific differences in the metabolism (synthesis and/or accumulation at the puff site) of the various hsr-omega transcripts, namely hsr-omega-nuclear (omega-n), omega-pre-cytoplasmic (omega-pre-c) and omega-cytoplasmic (omega-c). While heat shock increased the levels of all the three transcripts at the 93D puff site in a coordinated manner, benzamide led to a significant increase in the levels of hsr-omega-n and pre-c; on the other hand, colchicine caused increased levels of the omega-n and omega-c RNA species at 93D. The results also suggested splicing of hsr-omega-pre-c RNA at the site of synthesis with the spliced-out 'free' intron (hsr-omega-fi) accumulating at the puff site. The rate of splicing and/or turnover of the hsr-omega-fi varied in a treatment-specific manner. Although a combined treatment to salivary glands with heat shock and benzamide or colchicine is known to inhibit puffing and [3H]uridine incorporation at 93D, the two treatments resulted in a treatment-specific increase in the in situ levels of different hsr-omega transcripts at the 93D site, suggesting a reduced turnover of specific transcripts from the site under these conditions. We suggest that the different 93D transcripts have roles in turnover and/or transport of RNA in nucleus as well as some role in cytoplasmic translation.
authors.affiliation: Department of Zoology, Banaras Hindu University, Varanasi, India.
authors.forename: S C
authors.initials: SC
authors.lastname: Lakhotia
authors.forename: A
authors.initials: A
authors.lastname: Sharma
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics*; D002875:Chromosomes; D004331:Drosophila melanogaster / Q000235:genetics*; D017344:Genes, Insect; D005809:Genes, Regulator; D006360:Heat-Shock Proteins / Q000235:genetics*; D006358:Hot Temperature; D017403:In Situ Hybridization; D012313:RNA / Q000378:metabolism*; D015347:RNA Probes / Q000235:genetics; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D006360:Heat-Shock Proteins; D015347:RNA Probes; D012313:RNA