Expression patterns of cytochrome P450 3B and 3C genes in model fish species.

Cytochrome P450 (CYP) 3 enzymes are highly expressed in detoxification organs and play an important role in xenobiotic metabolism. In fish, the CYP3 family is diversified and includes several subfamilies (CYP3B, CYP3C, and CYP3D) not found in mammals. The functional role and expression patterns of these novel genes are unknown. In this study, the expression patterns of novel teleost CYP3 genes were determined in medaka(Oryzias latipes; CYP3B4, CYP3B5, CYP3B6) and zebrafish (Danio rerio; CYP3C1, CYP3C2, CYP3C3, CYP3C4), two important model fish species. Expression was quantified with real time PCR in multiple internal organs from adult male and female fish. CYP3C gene expression was determined in zebrafish embryos. Expression in all organs was detected for all genes, except for CYP3B4 in male organs. CYP3C1, CYP3C3, CYP3B4, CYP3B5, and CYP3B6 were more highly expressed in liver and/or intestine from at least one gender, suggesting a role in xenobiotic metabolism. Expression of CYP3C1 and CYP3B5 in olfactory rosette was comparable to liver. CYP3C1, CYP3C4, CYP3B5 and CYP3B6 expression was higher in the female organs; CYP3C2 and CYP3B5 were higher in testis. Estrogen and androgen response elements were found upstream of the start site of many of these genes raising the hypothesis that they are under steroid regulation. CYP3C1-3 were expressed in all developmental stages examined and appear to be maternally deposited. The expression patterns suggest that some of these CYP genes are involved in xenobiotic metabolism.