Genome-wide identification of 31 cytochrome P450 (CYP) genes in the freshwater rotifer Brachionus calyciflorus and analysis of their benzo[α]pyrene-induced expression patterns.

While marine invertebrate cytochrome P450 (CYP) genes and their roles in detoxification mechanisms have been studied, little information is available regarding freshwater rotifer CYPs and their functions. Here, we used genomic sequences and RNA-seq databases to identify 31 CYP genes in the freshwater rotifer Brachionus calyciflorus. The 31 Bc-CYP genes with a few tandem duplications were clustered into CYP 2, 3, 4, mitochondrial, and 46 clans with two marine rotifers Brachionus plicatilis and Brachionus koreanus. To understand the molecular responses of these 31 Bc-CYP genes, we also examined their expression patterns in response to benzo[α]pyrene (B[α]P). Three Bc-CYP genes (Bc-CYP3044B3, Bc-CYP3049B4, Bc-CYP3049B6) were significantly upregulated (P<0.05) in response to B[α]P, suggesting that these CYP genes can be involved in detoxification in response to B[α]P exposure. These genes might be useful as biomarkers of B[α]P exposure in B. calyciflorus. Overall, our findings expand the repertoire of known CYPs and shed light on their potential roles in xenobiotic detoxification in rotifers.