Interstrain comparison of glutathione-dependent reactions in susceptible and resistant houseflies

Glutathione S-alkyl- and S-aryltransferase activities and the glutathione-dependent reactions involved in the metabolism of diazinon, parathion, DDT and γ-BHC were determined in two susceptible and three resistant housefly strains. The relative rate of formation of desethyl diazinon and desethyl parathion and the degradation of γ-BHC paralleled the activities of the alkyl and aryltransferases in the various strains of houseflies suggesting that a single enzyme might be involved. DDT-dehydrochlorinase showed different relative rates among the strains indicating that the dechlorination was catalyzed by a different enzyme. The enzyme responsible for the conjugation of the pyrimidinyl moiety of diazinon appears to be different from the one which catalyzes the conjugation of the p-nitrophenyl moiety of parathion. The dearylation reactions were not mediated by the glutathione S-aryltransferase in the various housefly strains.