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 the unbleached biotreated pulp and paper mill effluent. The waste waters of a sulphite mill, producing unbleached semipulp and cellular board, were released into an inland water system. Cytochrome P450 related as well as conjugation enzyme activities were analyzed from the livers of perch (Perca fluviatilis) during different seasons. Part of the material was investigated by measuring the relative content of P4501A. protein. Further, physiological indices such as condition factor (CF), liver somatic index (LSI), and gonado somatic index (GSI) were calculated. Exposure to the unbleached sulphite mill effluent elevated 7-ethoxyresorufin O-deethylase (EROD) and 7-pentoxyresorufin O-dealkylase (PROD) activities in feral perch in the contaminated area in summer, compared to fish caught from an upstream control site. EROD activity was reflected 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 addition to causing enzyme induction, also suppressed catalytic EROD activities. Among conjugation enzyme activities, UDP-glucuronosyltransferase (UDP-GT) showed a slight statistical significance in winter. The LSI and 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 physiological parameters of perch.