Cytochrome P450s (CYPs) are present in almost all organisms and play critical roles in metabolism of endogenous substrates and detoxification of xenobiotic compounds. Oysters are a group of bivalves that are important in marine ecosystem and aquaculture program, adapting to the harsh environment in intertidal zones. The studies on CYPs and their potential involvement in dealing with toxic xenobiotics in oysters were limited. In the present study, we performed a multiple omics analyses and identified a full-set of 123 CYP genes in the Pacific oyster, Crassostrea gigas. These CYP genes were classified into 5 clans and 16 families. The phylogenetic tree constructed with other species showed extensive gene expansion of CYPs in the clan 2 and mitochondrial clan in the C. gigas. The amino acid sequence analysis showed conserved typical motifs of CYP genes. The expression profiles of CYPs quantified across different tissues (gill and digestive gland) at various time points (0d, 0.5d, 7d, 14d, 28d) revealed their roles in response to Cd exposure. Notably, CYP17A1-like_6 and CYP2C50 were expressed at significantly higher levels compared with other CYP genes, suggesting their crucial roles in the detoxification of Cd in the C. gigas. This work provides valuable information toward understanding of CYP-mediated detoxification of cadmium in mollusks, and will be important for surveillance of marine environment pollution and seafood safety.

细胞色素P450（CYP）几乎存在于所有生物中，并且在内源性底物的代谢和异源化合物的解毒中起关键作用。牡蛎是一组双壳类动物，在海洋生态系统和水产养殖计划中很重要，能适应潮间带的恶劣环境。CYP及其在处理牡蛎中毒性异种生物中的潜在作用的研究是有限的。在本研究中，我们进行了多个组学分析，并在太平洋牡蛎Crassostrea gigas中鉴定出123个完整的CYP基因。这些CYP基因被分为5个家族和16个家族。用其他物种构建的系统树表明CYPs在氏族2和线粒体在C. gigas中广泛扩展。氨基酸序列分析显示CYP基因的保守典型基序。在不同时间点（0d，0.5d，7d，14d，28d）在不同组织（g和消化腺）中定量的CYPs表达谱揭示了它们对Cd暴露的响应。值得注意的是，与其他CYP基因相比，CYP17A1-like_6和CYP2C50的表达水平明显更高，表明它们在C. gigas中Cd排毒中的关键作用。这项工作为了解CYP介导的软体动物中的镉排毒提供了有价值的信息，对于监测海洋环境污染和海产品安全将具有重要意义。