TISSUE LOCALIZATION, INDUCTION, AND DEVELOPMENTAL EXPRESSION OF CYTOCHROME-P450 MONOOXYGENASES IN THE GERMAN-COCKROACH

Methods of microsome preparation were evaluated to determine their inf luence on the activity of cytochrome P450 monooxygenases in adult male s and final instar nymphs of the German cockroach, Blattella germanica (L.). Aldrin epoxidase activity was significantly improved when homog enization occurred in a protected buffer and when alimentary canal con tents were removed prior to homogenization. Apparently, a potent inhib itor of cytochrome P450 monooxygenases, but not of cytochrome c reduct ase, is present in the gut contents of German cockroaches. Aldrin epox idase and methoxyresorufin (MR) O-demethylase activities were measured in separate tissues (foregut, midgut, hindgut, Malpighian tubules, fa t body, and the remaining tissues of the carcass) from adult males and final instar nymphs. Adult male aldrin epoxidase activity was highest in midgut and Malpighian tubules, while no single tissue dominated in MR O-demethylase activity. In final instar nymphs, aldrin epoxidase s pecific activity was 9- to 11-fold higher in midgut than in fat body, while MR O-demethylase specific activity was 17- to 22-fold higher in fat body than in midgut. In the final instar, aldrin epoxidase, MR O-d emethylase, ethoxyresorufin (ER) O-deethylase, and cytochrome c reduct ase activities were lowest at the time of ecdysis and highest near the middle of the stadium. Dietary phenobarbital at the 0.2% level induce d various microsomal oxidases including aldrin epoxidase, MR O-demethy lase, ER O-deethylase, and cytochrome c reductase in final instar nymp hs and adults. (C) 1996 Academic Press, Inc.