氧化石墨烯对双壳类动物文蛤的亚致死毒性研究

The sublethal toxicity of graphene oxide to bivalve Meretrix meretrix

为全面评价纳米材料对海洋生物的毒性效应,将文蛤暴露于含氧化石墨烯(GO,5mg/L)的人工海水,测定其内脏中的还原型谷胱甘肽(GSH)、氧化型谷胱甘肽(GSSG)、丙二醛(MDA)、乙酰胆碱酯酶(AChE)、金属硫蛋白(MTs)以及血细胞的微核率(MNF)和溶酶体膜稳定性(LMS)等7种生物标志物的变化,分析GO对双壳类的亚致死毒性机制.结果表明,GO能够诱导文蛤内脏的氧化逆境,表现为GSH含量降低、GSSG含量增加和MDA含量增加;GO产生的神经毒性较小,AChE活性仅在暴露初期与结束时短暂受抑;GO对MTs无诱导作用;GO暴露4d后即产生显著的遗传毒性和溶酶体膜失稳,MNF达到对照组的6.1~9.0倍,中性红保留时间(NRRT)降幅达到24.2%~49.2%.除AChE、MTs外,其它生化指标均适于作为指示GO亚致死毒性的敏感生物标志物.

In the present study,the experimental clams Meretrix meretrix were exposed to GO in artificial seawater(5mg/L)in order to comprehensively evaluate the toxicity of graphene nanomaterials to marine organisms.Mechanism of the sublethal toxicity caused by GO to clams was explored by monitoring of seven biomarkers including the reduced glutathione(GSH),oxidized glutathione(GSSG),malondialdehyde(MDA),acetylcholinesterase(AChE)and metallothioneins(MTs)in the digestive gland,as well as micronucleus frequency(MNF)and lysosomal membrane stability(LMS)of hemolymph.Results demonstrated that the oxidative stress was induced by GO in the digestive gland of clams,while the content of GSH decreased and both of GSSG and MDA increased.Weak neurotoxicity was caused by GO,which was indicated by the temporary inhibition of AChE activity at the initial and end of exposure stages.No obvious induction of MTs was observed in the whole period of exposure.However,significant genotoxicity and lysosomal membrane instability occurred after4-d exposure.The MNF of experimental groups reached to6.1~9.0times of the blank control levels,but the neutral red retention time(NRRT)decrease of the positive treatments was about24.2%~49.2%of the blank control group.Except for the biomarkers AChE and MTs,other parameters were testified as suitable and sensitive indicators to assess the sublethal toxicity of GO in this study.