NATURAL MODULATION OF HEPATIC METALLOTHIONEIN AND CYTOCHROME P4501A IN FLOUNDER, PLATICHTHYS-FLESUS L

The use of biomarkers such as cytochrome P4501A (CYP1A) or metallothio nein (MT) for pollution monitoring is based on the assumption that an increased activity or concentration is primarily caused by exposure to contaminants. Previous studies have shown that the response of biomar kers may be affected by factors such as season, temperature, gender, n utritional status or size. The objective of the present study was to i dentify natural factors that affect the hepatic activity of CYP1A and hepatic concentration of MT in flounder (Platichthys flesus L.). Thirt y flounder were sampled at each of two sites in the Hvaler archipelago , southern Norway, monthly through one year. A set of variables were r ecorded for each sampling and individual including water temperature, salinity, external and internal lesions, intestinal content, sex, size and organ weights. Hepatic CYP1A activity (EROD), MT and metal concen trations were determined for each individual flounder. The influence o f environmental and endogenous factors on the response of these two bi omarkers was assessed in multiple regression models. For both biomarke rs, 50-60% of the total variability could be explained from factors di rectly related to season, gender and maturation. Season contributed si gnificantly in the model for EROD, as did external lesions. Size, cond ition and diet did nor contribute greatly when the above factors, were included. The results confirm previous findings that season, gender a nd maturation must be taken into account in biomarker monitoring, but also indicate that other factors such as external lesions should be co nsidered. (C) 1998 Elsevier Science Ltd. All rights reserved.