Two CYP3A-like genes in the marine mussel Mytilus edulis: mRNA expression modulation following short-term exposure to endocrine disruptors

Members of the vertebrate CYP3A subfamily are involved in the metabolism of steroids and a wide range of xenobiotics. In this study two CYP3A-like mRNAs have been isolated from the mussel (Mytilus edulis), and their seasonal expression profile and modulation by estrogens examined. Sexual dimorphism of CYP3A-like mRNA expression was not observed in mussel gonads of individuals collected throughout a year. Nevertheless, natural variation in gonadal CYP3A-like mRNA expression was observed, with highest levels of CYP3A isoform1 and lowest levels of CYP3A isoform2 mRNA during the maturation and spawning season. Exposure to a 10% sewage treatment works extract did not result in any significant changes in mRNA expression of CYP3A-like. In contrast, exposure to E2 (200 ng/L) and TBT (100 ng/L) significantly down-regulated the expression of CYP3A-like isoform1 but not CYP3A-like isoform2 suggesting differential regulation.