THE INDUCTION OF CYTOCHROME-P-450 FORMS WITH BENZO[A]PYRENE IN 2 SPECIES OF DROSOPHILA - THE ROLE IN SUSCEPTIBILITY TO DDT AND BENZO[A]PYRENE

The DDT resistant 91R strain of D.melanogaster was shown to be essenti ally more sensitive to benzo[a]pyrene (BP) than the wild Oregon R stra in. The BP sensitive 364yv strain of D.simulans became relatively more resistant to DDT than the wild Turku strain after sublethal pretreatm ent with BP. The data of mixed-function oxidase activities measurement , SDS-PAGE of microsomal proteins and immunoblotting with MoAbs to D.m elanogaster cytochrome P-450 forms showed that the basal and (or) indu ced expression of P-450B forms with MW of 56.000 and 51.500 underlay i n the mechanisms of DDT resistance and BP susceptibility in 91R and 36 4yv. The inducibility of cytochrome P-450 by BP is higher in DDT resis tant and BP sensitive strains (91R and 364yv) comparing to the wild on es. However, the inducibility of microsomal monooxygenase activities b y BP in the wild strain Oregon R was shown to be increased by pretreat ment of the flies with phenobarbital. The possible mechanisms of the c ytochrome P-450 system induction by BP in Drosophila and the role of t his induction in the detection of chemicals carcinogenic preperties ha ve been discussed.