Development of cytochrome P450 as a biomarker of organic pollution in Mytilus sp.: field studies in United Kingdom ('Sea Empress' oil spill) and the Mediterranean Sea

Abstract

Literature on the properties, forms and regulation of cytochrome P450 (CYP) in digestive gland of Mytilus sp., including studies indicating the existence of an organic contaminant-inducible CYP1A-like protein, are briefly reviewed. Laboratory and field studies show increases in digestive gland microsomal CYP1A-immunopositive protein levels and/or benzo[a]pyrene hydroxylase (BPH) activity (i.e. metabolism of benzo[a]pyrene to phenols) with exposure of Mytilus sp. to certain polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls. In order to examine further the relationship between these two parameters, M. edulis were collected 25 and 130 days after the release of oil following the grounding of the tanker 'Sea Empress' in South Wales, UK (15 February 1996); and M. galloprovincialis were sampled from sites in south-western France and south-eastern Spain during a cruise aboard the IFREMER Research Vessel 'L'Europe' (2-18 August 1996). In both studies, sites with higher levels of CYP1A-immunopositive protein showed higher levels of BPH activities. Positive correlations were observed between the two measurements - R=0.65 (M. edulis) and 0.68 (M. galloprovincialis), and both fitted linear regression models (P < 0.05). The CYP1A-immunopositive protein levels and BPH activities tended to be highest at sites with greatest PAH body burden for the Mediterranean study. It is concluded that development of the CYP1A-like protein into a robust biomarker of exposure to organic contaminants will depend upon sequencing of the gene/protein and the subsequent production of Mytilus-specific cDNA and antibody probes. Such probes will then allow a full characterization of the enzyme's properties and gene regulation.