Genome-wide identification of 52 cytochrome P450 (CYP) genes in the copepod Tigriopus japonicus and their B[α]P-induced expression patterns.

Cytochrome P450s (CYPs) are enzymes with a heme-binding domain that are found in all living organisms. CYP enzymes have important roles associated with detoxification of xenobiotics and endogenous compounds (e.g. steroids, fatty acids, and hormones). Although CYP enzymes have been reported in several invertebrates, including insects, little is known about copepod CYPs. Here, we identified the entire repertoire of CYP genes (n=52) from whole genome and transcriptome sequences of the benthic copepod Tigriopus japonicus, including a tandem duplication (CYP3026A3, CYP3026A4, CYP3026A5), and examined patterns of gene expression over various developmental stages and in response to benzo[α]pyrene (B[α]P) exposure. Through phylogenetic analysis, the 52 T. japonicus CYP genes were assigned to five distinct clans: CYP2 (22 genes), CYP3 (19 genes), CYP4 (two genes), CYP20 (one gene), and mitochondrial (eight genes). Developmental stage and gender-specific expression patterns of the 52 T. japonicus CYPs were analyzed. CYP3022A1 was constitutively expressed during all developmental stages. CYP genes in clans 2 and 3 were induced in response to B[α]P, suggesting that these differentially modulated CYP transcripts are likely involved in defense against exposure to B[α]P and other pollutants. This study enhances our understanding of the repertoire of CYP genes in copepods and of their potential role in development and detoxification in copepods.