Cytochrome P450 expression is moult stage specific and regulated by ecdysteroids and xenobiotics in the crab Carcinus maenas

The shore crab Carcinus maenas has a high capacity for metabolizing polycyclic aromatic hydrocarbons (PAHs). Cytochrome P450 (CYP) enzymes are involved in this metabolism and also have a role in development and reproduction. This investigation is a systematic gene expression analysis of six CYPs in C. maenas. Expression of CYP2 and CYP3-like genes was predominant in hepatopancreas, while expression of CYP4-like genes was predominant in gills and epidermis. Expression of all six CYP genes fluctuated over the moult cycle in the hepatopancreas and structurally related genes were regulated coordinately. The study suggests that hepatopancreas is a major site of CYP gene expression in C. maenas confirming previous biochemical studies showing that this tissue is the major compartment for CYP mediated xenobiotic metabolism in crustaceans. In addition, the data show that CYP2 and CYP3 related genes respond to ecdysteroid and xenobiotic treatment, while those related to CYP4 genes do not and likely are involved in a more general physiological function such as fatty acid metabolism. The developmental variations of CYP expression suggest a molecular mechanism for the stage specific susceptibility of crabs exposed to environmental pollutants.