Induction of cytochrome P450 activities in Drosophila melanogaster strainssusceptible or resistant, to insecticides

We analysed Drosophila melanogaster cytochrome P450's (P450) through the me asurements of four enzymatic activities: ethoxycoumarin-O-deethylase, ethox yresorufin-O-deethylase, lauric acid hydroxylation, and testosterone hydrox ylation. We did these measurements in two Drosophila strains: one is suscep tible to insecticides (Canton(S)) and the other is resistant to insecticide s by enhanced P450 activities (RDDTR). In addition, we also treated the fli es with eight chemicals (beta-naphtoflavone, benzo-alpha-pyrene, 3-methylch olanthrene, phenobarbital, aminopyrine, rifampicin, prochloraz, and clofibr ate) known to induce genes from the families CYP1, CYP2, CYP3, CYP4, and CY P6. Metabolisation of all the substrates by P450 from flies microsomes was observed. The chemicals had different effects on these activities, ranging from induction to inhibition. The effects of these chemicals varied with th e strains as most of them were ineffective on the RDDTR strain. The results showed that P450-dependent activities are numerous in Drosophila. Regulati on features of these activities are complex. The availability of mutant str ains as RDDTR should allow fundamental studies of P450 in insects. (C) 1998 Elsevier Science Inc. All rights reserved.