A COMPARATIVE-STUDY OF EFFECTS OF ATRAZINE ON XENOBIOTIC-METABOLIZING ENZYMES IN FISH AND INSECT, AND OF THE IN-VITRO PHASE-II ATRAZINE METABOLISM IN SOME FISH, INSECTS, MAMMALS AND ONE PLANT-SPECIES

1. Atrazine (3 daily i.p. doses of 0.20 mg/kg or 10 ppb in the water for 14 days) did not change the xenobiotic metabolizing enzyme activities (XME) towards the substrates aldrin epoxidase (AE), NADPH-cytochrome c reductase (NCCR), 7-ethoxyresorufin O-deethylase (EROD), 1-chloro-2,4-dinitro-benzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB) in trout liver (Oncorhynchus mykiss) compared to the controls. 2. Various treatment regimens of atrazine in a semisynthetic diet changed the XME activities towards AE, NCCR, CDNB and DCNB in the cabbage moth (Mamestra brassica L.) soft tissues and midgut compared to the controls. 3. A fife-long cabbage diet induced the XME activity towards CDNB in the cabbage moth soft tissues and midgut, whereas no differences in the activities towards AE, NCCR and DCNB were observed compared to controls on a semi-synthetic diet. 4. The cabbage moth GSTs bound poorly to a glutathione (GSH)-linked epoxy-activated Sepharose 6-B; however, based on the CDNB activity recovered by a GSH elution, there were no differences in the molecular weights of the partly purified subunits (27, 26 and 25 kDa) or the pIs (5.4, 4.8, and 4.1) of the molecules in the soft tissues or midguts from respectively atrazine treated and control cabbage moth. 5. The presence of GST isozymes that metabolize atrazine has been demonstrated in all the 10 species studied (liver of the rainbow trout, starry flounder (Platichthys stellatus), English sole (Pleuronectes vetulus), rat (Rattus norvegicus, Sprague-Dawley), mouse (Mus musculus, CD-1), leaves of common groundsel (Seneco vulgaris) and midgut and soft tissues without gut of the cabbage moth and the Hebrew character moth (Orthosia gothica L.). 6. With the exception of common groundsel, the GST isozyme(s) with atrazine and ethacrynic acid (ETHA) activities are similarly distributed between the species.