In vivo metabolism of benzo(a)pyrene in the mussel Mytilus galloprovincialis

Abstract

The use of cytochrome P4501A (CYP1A) and other measurements as biomarkers was investigated in liver of goby (Z. ophiocephalus) and digestive gland of mussel (M. galloprovincialis) from several sites in the Venice lagoon as part of the UNESCO-MURST Venice Lagoon Ecosystem Project. Most tissue contaminants (PAHs, PCBs, DDTs) and biochemical measurements varied seasonally. Elevated 7-ethoxyresorufin O-deethylase activity and CYP1A-protein levels in goby were correlated with high tissue contaminant levels at the industrial Porto Marghera site. On occasions, activities of the antioxidant enzymes catalase and putative DT-diaphorase (resorufin reductase activity) in male but not female goby were also higher at Porto Marghera than other sites, but no differences were seen in Superoxide dismutase (SOD) activity. A range of measurements (SOD, catalase, NADPH-cytochrome c reductase and glutathione S-transferase activities, P450 and ‘418-peak’ contents) in mussel showed little difference between sites. However, indications were obtained of elevated levels of CYP1A1-like mRNA, CYP1A-like protein and metabolism of benzo[a]pyrene to free metabolites in mussels from the Venice lagoon compared to a site in the Adriatic Sea. The studies demonstrate the usefulness of CYP1A as a biomarker for organic pollution in fish and indicate some potential for its application in molluscs.