INDUCTION OF DIAPHORASE-1 BY DICOUMAROL IN DROSOPHILA-VIRILIS LARVAE

Drosophila diaphorase-1 (DIA-1) is an enzyme similar to mammalian DT-d iaphorase and is inhibited in vitro by dicoumarol. However, a ten-fold increase in DIA-1 activity was observed when third instar Drosophila virilis larvae were fed on a diet containing 0.1 M dicoumarol for 48 h . This induction was shown to be dose dependent and immunoprecipitatio n experiments with DIA-1 anti-serum demonstrated an increase in the DI A-1 protein level in dicoumarol-treated larvae. The induction of DIA1 by dicoumarol was found to be blocked by actinomycin D, which suggests a transcriptional mechanism of regulation. The opposite effect of dic oumarol on DIA-1 in vitro vs. in vivo suggests that a metabolic conver sion takes place after the ingestion of this compound by D. virilis la rvae. (C) 1995 Wiley-Liss, Inc.