Identification And Expression Of CYP3A Gene And Antioxidant Defense Exposed To Benzo[a]Pyrene And Cadmium In Thick Shell Mussel Mytilus Coruscus

In recent years,China's coastal waters environment has gradually deteriorated,heavy metals,organic and inorganic pollution is becoming more and more serious.Mytilus coruscus is an important characteristic economic shellfish in Zhoushan sea area of Zhejiang Province,which has high economic value and nutritional value.As a filter-feeding organism,mussels have a strong bioconcentration effect on pollutants in the marine environment.On the one hand,the heavy metals and persistent organic matter enriched in shellfish can be transmitted through the food chain,and then cause harm to human body;on the other hand,when the enrichment of pollutants exceeds the standard,it will also cause damage to the mussel itself,resulting in reduced disease resistance and frequent diseases.Understanding the stress mechanism of mussel in response to external environmental stimuli and screening the molecular targets of stress resistance can provide theoretical support for stress resistance breeding of mussel,which is of great significance for sustainable development of mussel industry.In view of the fact that cytochrome P450(CYP)superfamily is heme-thiolate protein,which plays a key role in the biosynthesis of endogenous compounds and metabolic transformation of exogenous substances,CYP3 A,as an important member of CYP450 family,its two subtypes McCYP3A1 and McCYP3A2,were cloned from Mytilus coruscus in this study.The molecular characteristics were identified,and temporal expression of McCYP3A1 and MCYP3A2 were analyzed in gills and digestive glands of mussel under single and combined exposure to cadmium and benzo(a)pyrene.Besides,in this study,lipid peroxidation(by measuring malondialdehyde MDA contents)and antioxidant enzymes including superoxide dismutase(SOD)and catalase(CAT)in mussels exposed to cadmium and benzo(a)pyrene were studied.The main results are as follows.The results showed that two CYP3 A isoforms gene were significantly induced under single and combined exposure to cadmium and benzo(a)pyrene,but displayed different expression patterns.The expression of McCYP3A2 gene was higher than that of McCYP3A1,and the expression of CYP3 A gene in digestive gland was higher than that ofgill,moreover,CYP3 A gene was more significantly induced under combined exposure than that under single exposure.Generally,These results showed that CYP3 A gene was significantly induced under the stress of exogenous substances and participated in the detoxification and metabolism of heavy metal cadmium and organic pollutant benzopyrene;the induction of antioxidant enzymes SOD and CAT activities,and the increase of MDA contents indicated that the body suffered oxidative damage and made protection,the results also showed that the oxidative damage of digestive glands was greater than that of gills,and the oxidative damage under combined pollution is greater than that of single pollution.