石墨烯联合磷酸三苯酯(TPP)胁迫紫贻贝(Mytilus galloprovincialis)的生理生化响应

Physiological and biochemistry responses of graphene combined with triphenyl phosphate(TPP)to Mytilus galloprovincialis

石墨烯纳米材料具有优良的吸附性能,进入环境后容易与其他污染物发生相互作用,进而影响其环境行为和毒理学效应.磷酸三苯酯(triphenyl phosphate,TPP)在环渤海中具有广泛的分布,且分子中含有多个苯环,易与石墨烯发生相互作用.为了研究石墨烯和TPP对海洋贝类生理响应的影响,采用指示生物紫贻贝(Mytilus galloprovincialis)进行了单一及联合暴露实验.通过对滤水率、耗氧率和排氨率的检测,分析了暴露物对紫贻贝生理代谢的影响;制作石蜡切片观察鳃和肝胰腺组织的结构变化;采用酶活试剂盒对肝胰腺组织中的抗氧化酶活性进行检测.结果表明,石墨烯和TPP单独暴露,均可对紫贻贝产生氧化胁迫和组织损伤.石墨烯和TPP联合暴露对紫贻贝的氧化胁迫和组织损伤程度,低于石墨烯单独暴露组.石墨烯对紫贻贝的耗氧率和排氨率均有显著影响(P<0.05).与对照组相比,石墨烯显著抑制紫贻贝的呼吸,增加紫贻贝的排氨率.TPP暴露后显著增加紫贻贝的排氨率.联合暴露后可降低由石墨烯引起的呼吸抑制,且升高氧氮比(O:N),说明联合暴露对机体造成的压力低于石墨烯单独暴露.综合生物标志物指数(IBR)结果显示,联合暴露对紫贻贝产生的胁迫压力低于石墨烯和TPP分别单独暴露.本研究结果可为预测海洋环境污染对贝类以及海洋生态系统产生的影响提供参考.

After released into the environment,graphene nanomaterials can interact with other pollutants,due to their excellent adsorption properties.This brings changes to the environmental behavior and toxicological effects of graphene nanomaterials and other pollutants.Therefore,it is of great significance to further investigate the joint toxic effects of graphene and other pollutants.Triphenyl phosphate(TPP)is an organophosphate flame retardant and widely distributed in the Bohai sea.TPP can interact with graphene easily,as it contains three benzene rings in the molecule structure.Previous studies showed that graphene could increase the accumulation of TPP because of its hydrophobicity and durability.Due to the increasing applications of graphene and TPP,it is of great significance to study the combined toxicological effects of graphene and TPP.Marine bivalves are important model organisms to assess the effects of nanoparticles on aquatic biota,and may play a significant role in nanoparticles uptake,biotransformation and trophic transfer through food chains.The physiological response index can be used to evaluate the effects of environmental stressors on marine bivalves.These physiological parameters not only present the key processes related to energy budget,but also reflect the physiological plasticity of animals to stress environments.As a species with high tolerance and efficient accumulation of pollutants,mussel Mytilus galloprovincialis has been widely used as the bioindicator for environmental monitoring and ecotoxicological research.In this study,the physiological responses of graphene and TPP on M.galloprovincialis were explored based on the analyses of five groups,including seawater control,DMSO control,graphene(0.5 mg/L),TPP(0.5 mg/L)and graphene(0.5 mg/L)+TPP(0.5 mg/L).The antioxidant status,physiological responses and histological changes of gill and hepatopancreas tissues were measured after 14-d exposure to graphene and TPP.The oxidative stress effects of graphene and TPP on M.galloprovincialis were examined by obtaining a series of enzyme activity indicators,such as the activities of catalase(CAT),superoxide dismutase(SOD),glutathione-s-transferase(GST),glutathione peroxidase(GPx)and the content of glutathione(GSH).The key physiological parameters that characterized changes in physiological response were measured,including clearance rate(CR),ammonia excretion rate(NR),oxygen consumption rate(OR)and oxygen to nitrogen(O:N).In addition,the integrated biological response(IBR)index was also calculated to compare the toxic effects of graphene,TPP and graphene+TPP on M.galloprovincialis.The results showed that the exposure of graphene+TPP mitigated oxidative stress and tissue damage in mussels induced by graphene.Graphene had significant effects on the oxygen consumption and ammonia excretion(P<0.05).Compared with the control group,graphene could significantly inhibit the OR of mussels and increased the NR.The NR of M.galloprovincialis was increased significantly after TPP exposure.Compared with the single graphene exposure,respiratory inhibition induced by graphene decreased,while oxygen-nitrogen ratio(O:N)increased after the combined exposure.It was evidenced that the combined exposure resulted in less environmental pressure on mussels compared with graphene exposure.The M.galloprovincialis was in a sub-health state after graphene and TPP exposure,and long-term continuous exposure could pose a potential threat to its population maintenance.In addition,IBR index showed that the combined exposure of graphene and TPP exhibited significantly lower stress on mussels,compared with the exposure of graphene and TPP,respectively.