栉孔扇贝对8:2FTCA的代谢转化与氧化应激响应

Metabolic transformation and physiological response of Chlamys farreri to 8:2 fluorotelomer carboxylic acid(8:2FTCA)

以栉孔扇贝(Chlamys farreri)为受试生物,研究了栉孔扇贝对8:2氟调聚羧酸(8:2FTCA)的代谢转化特征以及代谢过程中靶器官的氧化应激响应.结果发现,栉孔扇贝可将8:2FTCA转化为8:2氟调聚不饱和酸(8:2FTUCA)、7:3氟调聚羧酸(7:3FTCA)、全氟辛酸(PFOA)、全氟壬酸(PFNA)和全氟庚酸(PFHpA)等代谢产物.栉孔扇贝鳃和肝脏中代谢产物总量最高,为8:2FTCA的主要代谢靶器官.与本课题组前期虾夷扇贝的相关研究相比,8:2FTCA在栉孔扇贝与虾夷扇贝体内的生物转化行为主要有3方面相似之处:检测到的代谢产物相同、代谢靶器官相同以及鳃是最终代谢产物PFOA生成和蓄积的主要场所;不同之处主要体现在栉孔扇贝中代谢产物以7:3FTCA占比较高,虾夷扇贝中则是PFOA占比较高.同时在8:2FTCA暴露过程中,栉孔扇贝靶器官的关键抗氧化酶出现了一定的应激效应.丙二醛(MDA)和谷胱甘肽(GSH)等氧化应激指标以及谷胱甘肽过氧化物酶(GSH-Px),超氧化物歧化酶(SOD)和过氧化氢酶(CAT)等抗氧化酶系出现不同程度变化:GSH-Px在整个代谢转化过程中呈现抑制效应;SOD,CAT活性在鳃中呈诱导效应,而在肝脏中呈现明显的剂量-效应关系,低剂量组中均呈抑制效应,高剂量组中大部分时间呈诱导效应.GSH和MDA含量不仅表现出剂量-效应关系,组织间也存在差异.暴露实验结束后,生理指标均有不同程度恢复.

The metabolic transformation characteristics and oxidative stress response of Chlamys farreri to 8:2 fluorotelomeric acid(8:2 FTCA)were studied.Five metabolites of 8:2 FTCA were identified in C.farreri,inclubng 8:2 fluorotelomer unsaturated carboxylic acid(8:2 FTUCA),7:3 fluorotelomer carboxylic acid(7:3 FTCA),perfluorooctanoic acid(PFOA),perfluorononanoic acid(PFNA)and perfluoroheptanoic acid(PFHpA).Gill and liver were the main metabolic target organs which the total concentration of metabolites were the highest.The biotransformation characteristics of 8:2 FTCA in C.farreri was similar with that in Patinopecten yessoensis,such as the detected metabolites,the metabolic target organs,and the main tissue for the accumulation and metabolism of PFOA(gill).The difference was the main metabolite of C.farreri is 7:3 FTCA while P.yessoensis is PFOA.The key antioxidant enzymes in gill and liver were activated significantly.Oxidative stress indicators such as malondialdehyde(MDA)and glutathione(GSH),antioxidant enzymes such as glutathione peroxidase(GSH-Px),superoxide dismutase(SOD)and catalase(CAT)changed in different degrees:GSH-Px was inhibited continuously during the entire experiment,SOD and CAT activities were induced in gill,and showed obvious dose-effect relationships in the liver:inhibited in the low-dose treated groups,and induced in high-dose treated groups.The content of GSH and MDA showed a dose-response relationship as well as tissue variability.In addition,physiological indicators recovered in various degrees at the end of the exposure experiment.