Induction of mixed-function oxygenase system and antioxidant enzymes in the coral Montastraea faveolata on acute exposure to benzo(a)pyrene.

Components of the cytochrome P(450) monooxygenase system (MFO) and antioxidant enzymes were investigated in the coral Montastraea faveolata exposed to the organic contaminant benzo(a)pyrene (B(a)P). For bioassays the corals were exposed to increasing concentrations of B(a)P (0.01 and 0.1 ppm) for 24 and 72 h, with water renewal every 24 h. Enzymatic activity of catalase (CAT), superoxide dismutase (SOD) and glutathione S-transferase (GST) were measured in host (polyp) and hosted (zooxanthellae) cells. NADPH cytochrome c reductase activity and contents of cytochrome P(450) and P(420) were only measured in the polyp. Antioxidant enzymes CAT and SOD in polyps and zooxanthellae and GST in polyps increased significantly at the highest concentration and maximum time of exposure. Cytochrome P(420) was found in all colonies, and the cytochrome P(450) content was greatest in the colonies from the highest concentrations of contaminant. NADPH cytochrome c reductase activity and the concentration of pigments did not vary between treatments. This is the first report of the induction of both detoxifying mechanisms, the MFO system and antioxidant enzymes on acute exposure to an organic contaminant in the reef-constructing coral species M. faveolata.