title: Effect of insect hormones on RNA polymerases of mass-isolated imaginal discs of Drosophila melanogaster cultured in vitro.
abstract: Four chromatographically separable DNA-dependent RNA polymerases (nucleosidetriphosphate:RNA nucleotidyltransferase; EC 2.7.7.6) were partially purified from imaginal discs of Drosophila melanogaster. Their properties are similar to those described for RNA polymerases I and II isolated from other eukaryotes. In vitro incubation of discs with beta-ecdysone, juvenile hormone, or cycloheximide resulted in increased activity of RNA polymerase I. The increase was irreversible with beta-ecdysone incubation and removal but reversible with juvenile hormone incubation and removal. With beta-ecdysone, the rate of the increase in polymerase I activity paralleled the kinetics of ecdysone binding to discs and increases in the rate of precursor incorporation into RNA. A model to explain the increased acticity of RNA polymerase I is presented.
mesh_terms: D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D003513:Cycloheximide / Q000494:pharmacology; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000187:drug effects / Q000201:enzymology*; D004440:Ecdysone / Q000494:pharmacology*; D007527:Isoenzymes / Q000378:metabolism; D007605:Juvenile Hormones / Q000494:pharmacology*; D007700:Kinetics
chemical_list: D000546:Amanitins; D007527:Isoenzymes; D007605:Juvenile Hormones; D004440:Ecdysone; D003513:Cycloheximide; D012321:DNA-Directed RNA Polymerases