HEPATIC CYTOCHROME P4501A AND OTHER BIOTRANSFORMATION ACTIVITIES IN PERCH (PERCA-FLUVIATILIS) - THE EFFECTS OF UNBLEACHED PULP-MILL EFFLUENTS

The present study describes the use of enzyme based biomonitoring of t he unbleached biotreated pulp and paper mill effluent. The waste water s of a sulphite mill, producing unbleached semipulp and cellular board , were released into an inland water system. Cytochrome P450 related a s well as conjugation enzyme activities were analyzed from the livers of perch (Perca fluviatilis) during different seasons. Part of the mat erial was investigated by measuring the relative content of P4501A. pr otein. Further, physiological indices such as condition factor (CF), l iver somatic index (LSI), and gonado somatic index (GSI) were calculat ed. Exposure to the unbleached sulphite mill effluent elevated 7-ethox yresorufin O-deethylase (EROD) and 7-pentoxyresorufin O-dealkylase (PR OD) activities in feral perch in the contaminated area in summer, comp ared to fish caught from an upstream control site. EROD activity was r eflected in the enhanced amounts of P4501A (or CYP1A) protein found in fish downstream to the discharge sewer. Assay of the P4501A. protein content suggested that the effluent contained agents which, in additio n to causing enzyme induction, also suppressed catalytic EROD activiti es. Among conjugation enzyme activities, UDP-glucuronosyltransferase ( UDP-GT) showed a slight statistical significance in winter. The LSI an d CF were slightly increased in perch inhabiting the polluted waters. Based on the current findings it is suggested that unbleached sulphite effluents can cause some changes in xenobiotic metabolism and in phys iological parameters of perch.