Biomarkers of contaminant exposure in Chub (Leuciscus cephalus L.) -: Biomonitoring of major rivers in the Czech Republic

Biochemical analysis of organisms to assess exposure to environmental contaminants is of great potential use. Biochemical markers, specifically liver enzymes of the first and the second phase of xenobiotic transformation-cytochrome P-450 (CYP 450), ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and tripeptide reduced glutathione (GSH)-were used to assess contamination of the aquatic environment at 12 locations near the mouths of major rivers in the Czech Republic. These rivers were the Luznice, Otava, Sazava, Berounka, Vltava, Labe, Ohre, Svratka, Dyje, Morava and Odra. The indicator species selected was the Chub (Leuciscus cephalus L.). The highest levels of CYP 450 and EROD catalytic activity were found in livers of fish from the Labe (Obristvi) (0.32 +/- 0.10 nmol mg(-1) protein and 1061.38 +/- 545.51 pmol min(-1) mg(-1) protein, respectively). The highest levels of GST catalytic activity and GSH content were found in fish from the Otava (35.39 +/- 13.35 nmol min(-1) mg(-1) protein and 4.29 +/- 2.10 nmol GSH mg(-1) protein, respectively). They were compared with levels of specific inductors of these biochemical markers in muscle. The results confirmed contamination of some river locations (Labe Obristvi, Svratka).