纳米氧化镍颗粒对长牡蛎(Crassostreagigas)抗氧化防御体系的影响

纳米氧化镍(nNiO)作为一种广泛使用的纳米颗粒,其水生毒理效应研究还很有限。为探索n Ni O对海洋贝类的毒性机制,本研究将长牡蛎(Crassostrea gigas)置于不同浓度(0、1、10、100 mg·L~(-1))的n Ni O中暴露96 h,分别测定鳃和消化腺组织的丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化物酶(POD)以及过氧化氢酶(CAT)活性,并通过实时荧光定量PCR技术测定了鳃和消化腺中应激蛋白HSP70和AOX基因的表达变化。结果显示:在100 mg·L~(-1)n Ni O处理下,2种组织中MDA含量均显著性升高(P0.01),显示纳米颗粒造成了长牡蛎的脂质过氧化,并可能引起相应的氧化损伤。同时,n Ni O暴露也诱导了长牡蛎抗氧化酶(SOD、CAT和POD)活性的改变。其中,SOD和CAT活性在10 mg·L~(-1)浓度处理组达到最高,而POD活性在1 mg·L~(-1)浓度组即达最高值。在高浓度n Ni O(100 mg·L~(-1))胁迫下,3种抗氧化酶的活性均比低浓度(1和10 mg·L~(-1))处理组降低,表明抗氧化酶的保护作用在较低浓度暴露下更有效;而热激蛋白(hsp70)和交替氧化酶(aox)基因却分别在长牡蛎消化腺和鳃组织中上调表达(P0.01),并表现出一定的组织差异。说明高浓度纳米颗粒暴露中主要是应激蛋白发挥了作用。本文结果为纳米氧化镍对海洋双壳贝类的毒性机制研究及生态风险评估提供了基础数据。

Effects of Nickel Oxide Nanoparticles on Antioxidant Defense System of Crassostrea gigas

Nano-nickel oxide (nNiO) is a widely used nanoparticle, and the research on aquatic toxicological effects of nNiO was limited, especially for marine organisms. To explore the mechanism of toxicity of nNiO to marine bivalve molluscs, the Pacific oysters (Crassostrea gigas) were exposed to nNiO at different concentrations (0, 1, 10, 100 mg L^-1) for 96 h in the present study. The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and malondialdehyde (MDA) content in gill and digestive glands were measured. The expression changes of the shock protein HSP70 and AOX gene in gill and digestive gland were also determined by real-time fluorescence quantitative PCR. The results showed that the content of the MDA in both tissues increased significantly (P<0.01) in the 100 mg L^-1 treatment group, suggesting that the nanoparticles caused lipid peroxidation of oysters and may cause oxidative damage. Meanwhile, nNiO exposure also induced changes in the antioxidant enzymes (SOD, CAT, and POD) activities of oysters. The SOD and CAT activities reached the maximum in the 10 mg L^-1 treatment group, while the POD activity reached the highest in the 1 mg L^-1 concentration group. At high concentrations of nNiO (100 mg L^-1) group, the activities of the three antioxidant enzymes were lower than those in lower concentrations (1 and 10 mg L^-1), indicating that the activities of antioxidant enzymes were repressed by higher concentrations of nNiO exposure. However, heat shock protein (hsp70) and alternative oxidase (aox) genes were up-regulated in digestive glands and gills, respectively (P<0.01). It is indicated that the stress protein (HSP70 and AOX) played a key role with higher nNiO exposure concentration. The results provided basic data for the study on the toxicity mechanism of nano-nickel oxides to marine bivalve molluscs.