SEASONAL-VARIATION IN THE MIXED-FUNCTION OXYGENASE SYSTEM AND ANTIOXIDANT ENZYMES OF THE MUSSEL MYTILUS-GALLOPROVINCIALIS

Seasonal variations in the mixed-function oxygenase (MFO) system components (cytochrome P450, ''418'' peak, and NADPH-cytochrome c[P450] reductase) and antioxidant enzymes (catalase, superoxide dismutase [SOD], glutathione peroxidase [GPX], and DT-diaphorase) of the mussel Mytilus galloprovincialis have been evaluated. Its relation with contaminant body burden (PAHs, PCBs, DDTs, and lindane) as well as environmental parameters (water temperature, salinity, oxygen concentrations, and suspended matter) was determined. As a general trend, low MFO and antioxidant enzyme activities were detected in February-March, a peak in late April, and a gradual decrease with a minimum in June. This pattern was similar to tissue concentrations of PAHs, PCBs, DDTs, and lindane normalized to lipid weight. Cytochrome P450 content, however, exhibited a steady decrease from February to June. The observed seasonal variations are presumably related to the metabolic status of the animal, itself dependent on such factors as gonadal ripening, food availability, and the hydrological cycle, which regulates productivity in the area.