title: Stress response in Drosophila subobscura: DNA-RNA hybrids and transcriptional activity.
abstract: Immunofluorescent techniques have been used in the analysis of DNA-RNA hybrids occurrence and its relationship to transcriptional events on polytene chromosomes of Drosophila subobscura. We have studied the distribution of these hybrids on uninduced/induced chromosomes. Two different indirect immunofluorescence methods for the detection of DNA-RNA hybrids were used. Our data confirm the positive correlation between localization of DNA-RNA hybrids and transcriptional activity by following the Büsen et al procedure (1982). Using the other protocol, which allows chromosomal DNA-RNA to denature and renature, makes DNA-RNA hybrids detectable not exclusively in active chromosomal regions. Taking Büsen as method of choice, this technique allowed to localize the exact transcriptional active sites on puffs: hybrid fluorescence was restricted to marginal or central puff areas. Moreover, no correlation between fluorescence and puffs size was found. However, our studies on induced chromosomes indicate that: 1) the 15DE puff, previously described as t-puff, was not really a heat shock puff, since no transcriptional activity was detected; 2) hybrid fluorescence at 2C and 31CD regions was observed. No labelling was found in these loci in the autoradiography data, reported by other authors.
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000737:chemistry / Q000648:ultrastructure; D004247:DNA / Q000032:analysis*; D004330:Drosophila / Q000235:genetics / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D009691:Nucleic Acid Denaturation; D009693:Nucleic Acid Hybridization; D012313:RNA / Q000032:analysis*; D012333:RNA, Messenger / Q000096:biosynthesis; D013312:Stress, Physiological / Q000235:genetics / Q000503:physiopathology*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D012313:RNA; D004247:DNA