腹泻性贝毒是最常见的贝毒之一，人们误食其污染的贝类时，可造成腹泻性中毒，甚至可引致肿瘤发生。但贝类对其有一定的耐受性，且不同贝类对毒素的毒性响应存在很大差异。我们推测，生物转化中重要的I相酶细胞色素P450（CYP450）可能在DSP毒素的代谢解毒过程中发挥重要作用。本课题采取体外代谢实验和贝类整体动物实验相结合的手段，以翡翠贻贝等为实验对象，通过染毒后贝类的转录组研究，DSP毒素主要成分OA的体外代谢分析，细胞色素P450不同亚型基因的表达与毒素代谢的关系分析，以及不同贝类细胞色素P450亚型基因表达与毒素积累和对毒素毒性响应的比较分析等，研究毒素的代谢途径，探讨细胞色素P450在DSP毒素代谢解毒中的作用，为深入认识DSP毒素在贝体中的代谢解毒过程和耐受机制，明确不同贝类对毒素相应差异的原因奠定基础，为染毒贝类的净化与贝类的健康养殖提供理论基础。

Diarrhetic shellfish poisoning (DSP) toxins, one of the most important shellfish toxins, are found in the sea area all over the world. DSP toxins can lead to diarrhetic poisoning of humanity, and moreover, induce tumor. But bivalves have some tolerance to DSP toxins, and various bivalve species exhibit different sensibility to the toxicity of DSP toxins. Nevertheless, the metabolism and detoxification of DSP toxins in bivalve species remains unclear. Cytochrome P450 (CYP450) enzymes is a very important superfamily involved in detoxification and resistance, which mainly transform liposoluble toxic chemicals into hydrosoluble substances easily eliminated. In this study, in vitro metabolism experiment and integral animal experiment will be conducted to explore the roles of CYP450 in metabolism and detoxification of DSP toxins in bivalve. RNA sequencing and de novo assembly of the digestive gland and gill transcriptome in Perna viridis fed with toxic Prorocentrum lima will be firstly done, and expression profiles of CYP450 isoforms involved in detoxification of DSP toxins will be analyzed. Then, metabolism of okadaic acid (OA), a main component of DSP toxins will be performed in vitro, and metabolites of OA will be analyzed. Thirdly, some potential CYP450 isoforms involved in DSP toxin detoxification in bivalve will be silenced by RNAi technique, and effect of silencing genes on toxins metabolism and susceptibility of bivalve to OA will be investigated to distinguish which isozymes are responsible for DSP toxin detoxification. Finally, the responses, DSP content and CYP450 isoforms expression will be compared between different bivalve species after exposed to P. lima. Our project will provide new insights into the metabolism and detoxification of DSP toxins in bivalve species.