Dietary crude oil exposure during sexual maturation induces hepatic mixed function oxygenase (CYP1A) activity at very low environmental temperatures in Polar cod Boreogadus saida

Abstract

Previous studies have indicated that hydrocarbon induction of the h e p a t ~c microsomal monooxygenase Cytochrome P450 1A (CYPlA) is attentuated in certain species of fish by low temperature and in sexually mature female fish by estradiol. This enzyme 1s used as a biomarker for petroleum hydrocarbon exposure, and with impending oil exploration of the Arctic, in particular the Barents Sea, the current studies were carried out to establish the nature of the response of hepatic CYPlA to dietary petroleum hydrocarbon injestion in Polar cod at their natural environmental temperatures during the breed~ng season Polar cod Boreogadus salda maintained at 0C contain a hepatic CYPlA which displays immunochernical and nucleotide homology with other piscine CYPlAs and displays typical transcnptional induction by R-napthoflavone or crude mineral oil. The enzyme is induced in both male and female fish fed artificial diets contaminated by crude oil during the period of sexual maturation despite an overall suppression of activity in female fish and a cessation of feeding for 3 wk immediately prior to spawning. The results Indicate that use of CYPlA measurements in this species for biomonitoring oil exploration and production in the Arctic environment is a valid procedure.