CYTOCHROME-P450 OBSERVATIONS IN GULF FISH

Samples from nine fish species caught at different sites in the Gulf during leg IV of the Mt Mitchell cruise in the spring of 1992 were analysed for levels of cytochrome P450 1A enzymes. P450 monooxygenases catalyse the first step in the biotransformation of lipophilic xenobiotics. The P450 1A enzyme subfamily is induced by planar, organic compounds, and is used as a biomarker for exposure to oil compounds and PAH-type xenobiotics. The P450 1A analyses of the samples included both a catalytic method (EROD activity measurements) and immunochemical methods (Western blotting and an indirect ELISA). Polyclonal antibodies against P450 1A1 from cod (Gadus morhua) were used in the immunochemical assays. The Western blotting results demonstrated strong cross-reaction between polyclonal anti-cod P450 1A1 IgG and a single protein band with an M(r) of approximately 58 kDa in eight species examined. Elevated EROD levels were found in fish caught at the northern stations compared to individuals of the same species caught further south. The results from the P450 1A1 ELISA analyses supported these findings, although with some differences between species. Overall, conclusive statements about the P450 1A status in fish from the survey area are difficult to make from this investigation. This is mainly due to diverse species composition and the small size of the catches at the different fishing locations.