单壁碳纳米管对太平洋牡蛎(Crassostrea gigas)的毒性效应及生物体防御机制研究

Study on Toxicity of Single-Walled Carbon Nanotubes (SWCNTs) to Pacific Oyster (Crassostrea gigas) and the Defense Mechanism Involved

碳纳米管的生态安全和健康风险日益受到人们的广泛关注。本文采用典型的海洋底栖生物——太平洋牡蛎(Crassostrea gigas,C.gigas)作为受试生物,研究了单壁碳纳米管(Single-Walled Carbon Nanotubes,SWCNTs)暴露对其造成的毒性效应及牡蛎自身的防御机制,以期为碳纳米管的海洋生态风险评价提供科学依据。在0.1~10mg·L^-1的SWCNTs暴露96h后,太平洋牡蛎鳃和消化腺中的丙二醛(malondialdehyde,MDA)含量显著增加(P≤0.05),总超氧化物歧化酶(superoxidedismutase,SOD)和过氧化氢酶(catalase,CAT)活性呈现显著的剂量依赖性升高(P≤0.05),cat、hsp70、aox及caspase-7等基因的相对表达量显著上调(P≤0.05)。相比于单独暴露,P-gp蛋白抑制剂Tariquidar与SWCNTs的复合暴露显著增加了鳃和消化腺中MDA含量,产生了更严重的氧化损伤。这些结果表明,SWCNTs暴露对太平洋牡蛎的鳃和消化腺造成了一定程度的氧化损伤,而牡蛎体内的抗氧化系统和多外源性物质抗性机制在防御SWCNTs的过程中起到了至关重要的作用。

The ecological and health risks of carbon nanotubes are receiving more attention.In this study,Pacific oyster ( Crassostrea gigas ),a kind of typical marine benthic organism,was exposed to single-walled carbon nanotubes (SWCNTs) to investigate the toxicity induced by SWCNTs and the defense mechanism of C.gigas.After 96-h exposure to 0.1 -10 mg L^-1 SWCNTs,the content of malondialdehyde (MDA) in gills and digestive glands increased significantly (P≤0.05),the activities of total superoxide dismutase (SOD) and catalase (CAT) showed the significant dose-dependent increase ( P≤0.05),and the relative expressions of genes,i.e.,cat,hsp70,aox and caspase-7,were significantly up-regulated ( P ≤0.05).The co-exposure of Tariquidar (P-gp protein inhibitor) and SWCNTs induced the significant increase of the MDA content in gills and digestive glands ( P ≤0.05),indicating that more serious oxidative damage were caused by the mixture.The results revealed that the antioxidant system and Multi-xenobiotic Resistance Mechanism played vital roles in the defense system of Pacific oyster against the SWCNTs exposure.