APPLICATION OF A SENSITIVE CHEMILUMINESCENT TECHNIQUE FOR COMPARISON OF CYTOCHROME P4501A INDUCTION IN HEPATIC AND INTESTINAL TISSUES OF FISH EXPOSED TO BLEACHED KRAFT MILL EFFLUENT

In conjunction with an environmental assessment of biologically-treate d bleached kraft mill effluent (BKME) in a Western Canadian river, dat a indicated that lipophilic compounds were transferred to the mountain whitefish Prosopium williamsoni through ingestion of filter-feeding b enthic caddisflies. P4501A induction was correlated with lipophilic bo dy burdens, not with indices of recent BKME exposure. P4501A contents in hepatic and intestinal tissues of BKME-exposed whitefish were compa red during a follow-up collection. Ethoxyresorufin O-deethylase (EROD) activity was not detectable in intestines; P-450 spectral analysis in dicated denaturation had occurred. Use of enhanced chemiluminescence ( ECL) immunoblotting achieved at least 10-fold greater sensitivity over colorimetric methods and indicated that some intestines did contain P 4501A protein. No correlation of intestinal P4501A with hepatic EROD a ctivity or P4501A content was found. Application of the ECL technique significantly improves the analytical detection limits of P4501A immun oblotting. Analysis of historical samples from this site will further probe water-borne versus dietary routes of uptake of BKME-related P450 1A inducers in this species.