RESUMO
Small chromosomal deletions [Df(3R)eR-1 and Df(3R)eP] with intact hsromega transcription units but with variable deletions of the upstream region were used to map the upstream regions that regulate heat shock and amide responsivity of the 93D puff (hsromega locus) in salivary glands of late third instar larvae of Drosophila melanogaster. The Df(3R)eP deletion, generated by a P-element mobilization screen, removed the 93B6-7 to 93D3-5 cytogenetic region. [3H]uridine-labeled transcription autoradiograms revealed that normal developmental and heat shock-induced expression of the 93D puff remained unaffected in both the deficiency chromosomes. However, the amide responsivity of the 93D site was lost on the Df(3R)eP homolog while the Df(3R)eR-1 homolog responded normally to amides. Southern hybridizations with a series of upstream probes mapped the distal breakpoint of the Df(3R)eP deletion between -22 kb and -23 kb of the hsromega transcription unit. Since the distal breakpoint of Df(3R)eR-1 is at about -45 kb upstream of the hsromega gene it is inferred that the amide response element(s) that modulate the specific transcriptional activation of the 93D puff following treatment of salivary glands with a variety of amides is/are located in the -22 kb to about -45 kb upstream interval. The Df(3R)eP and Df(3R)eR-1 deletions also abolished dosage compensation at the 93D locus as well as the effect of beta-alanine levels on its heat shock inducibility.
Assuntos
Regiões 5' não Traduzidas/genética , Amidas/farmacologia , Mapeamento Cromossômico/métodos , Proteínas de Drosophila , Drosophila melanogaster/genética , Genes de Insetos , Resposta ao Choque Térmico/genética , Regiões 5' não Traduzidas/efeitos dos fármacos , Animais , Proteínas de Ligação a DNA/genética , Genes de Insetos/efeitos dos fármacos , Mutação , Transcrição Gênica , Translocação GenéticaRESUMO
We report here that 3-aminobenzamide and other amides, such as formamide, acetamide and nicotinamide, specifically induce a high rate of transcription at the 93D puff (the hsr omega heat shock gene) in polytene chromosomes of Drosophila melanogaster. Other chemicals, such as benzamide, colchicine, thiamphenicol and paracetamol, that are already known to specifically induce transcription at the hsr omega locus are also identified as amides. In view of the specific induction of the 93D puff by different amides and other data that demonstrate hsr omega transcription in response to benzamide and colchicine etc. to be independent of its heat shock induction, it appears likely that amides induce this locus through distinct regulatory elements that we propose to designate amide response elements (AREs).
