微塑料和芘对菲律宾蛤仔的毒性效应研究

Toxic effects of polystyrene microplastics and pyrene on Ruditapes philippinarum

海洋环境中微塑料和多环芳烃(PAHs)污染日益严重,以滤食动物菲律宾蛤仔(Ruditapes philippinarum)为研究对象,探讨了聚苯乙烯微塑料和芘单一及联合暴露对菲律宾蛤仔的毒性效应。分别采用两个聚苯乙烯微塑料粒径(0.3μm和6μm,20μg/L)和两个芘浓度水平(10μg/L和100μg/L)单独和联合暴露21 d,测定其对菲律宾蛤仔生理活动(肥满度和摄食率)、免疫防御、氧化应激等相关生物标志物的影响。研究结果表明,除芘单一暴露组外,其余暴露组菲律宾蛤仔的摄食率与对照组相比都显著降低,但这两种污染物对菲律宾蛤仔的肥满度没有显著影响。微塑料和芘暴露均导致菲律宾蛤仔免疫功能受损,表现为血细胞凋亡率增加和吞噬活性被抑制;其中,在小粒径微塑料和高浓度芘存在的暴露组血细胞凋亡率均显著高于对照组,并且二者联合暴露组血细胞凋亡率最高;除大粒径微塑料暴露组外,各暴露组血细胞吞噬活性均显著低于对照组。菲律宾蛤仔抗氧化酶系统不能及时清除体内产生的自由基,导致机体出现氧化损伤现象,表现为抗氧化酶活性变化和丙二醛(MDA)含量升高。微塑料和芘联合暴露导致鳃组织谷胱甘肽巯基转移酶(GST)活性显著升高,消化腺组织过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性显著降低。综合生物标志物指数(IBR)结果显示,联合暴露对菲律宾蛤仔造成的胁迫压力高于单一暴露组。

The pollution of microplastics and polycyclic aromatic hydrocarbons(PAHs)in marine environment is increasingly serious.The toxic effects of polystyrene microplastics and pyrene on the clam Ruditapes philippinarum were investigated in this study.R.philippinarum was exposed to two polystyrene microplastics sizes(0.3μm and 6μm,20μg/L)and two pyrene concentrations(10μg/L and 100μg/L)for 21 days,respectively.For individuals in each treatment,physiological responses(condition index and clearance rate),immune defense and oxidative stress parameters were measured.It was found that except for the pyrene single exposure group,the clearance rate of R.philippinarum in the other exposure groups was significantly lower than that of the control group,but the two pollutants had no significant effect on the condition index of R.philippinarum.Exposure to microplastics and pyrene led to impaired immune function of R.philippinarum,manifested by increased hemocyte apoptosis and inhibited phagocytosis.The apoptosis rate of hemocytes in the exposure group with small size microplastics and high concentration pyrene was significantly higher than that in the control group,and the apoptosis rate of hemocytes in the combined exposure group was the highest.Except for the large size microplastic exposure group,the phagocytic activity of hemocytes in each exposure group was significantly lower than that of the control group.The antioxidant system of R.philippinarum could not remove the free radicals produced in the body in time,leading to oxidative damage in the body,which was manifested as the change of antioxidant enzyme activity and the increase of malonic dialdehyde(MDA)content.The combined exposure of microplastics and pyrene significantly increased the activities of glutathione S-transferase(GST)in gill tissues,and significantly decreased the activities of catalase(CAT)and superoxide dismutase(SOD)in digestive gland tissues.Integrated biomarker response(IBR)analysis showed that the stress caused by combined exposure on R.philippinarum was higher than that of the single exposure group.