纳米硒对低氧胁迫下中华绒螯蟹免疫保护和抗氧化能力的影响

Effects of nanometer selenium on immune protection and antioxidant ability of Eriocheir sinensis under hypoxia stress

低氧胁迫会减弱中华绒螯蟹(Eriocheir sinensis)的免疫机能和抗氧化能力。为揭示纳米硒(nano-Se)对低氧胁迫下中华绒螯蟹的免疫保护作用及抗氧化调控机制,在基础饲料中添加不同水平(0、0.1、0.2、0.4、0.8和1.6 mg·kg^(−1))的纳米硒饲喂中华绒螯蟹90 d。饲喂实验结束后,进行低氧胁迫实验并注射嗜水气单胞菌(Aeromonas hydrophila)。结果表明:1)低氧胁迫24 h和低氧胁迫下感染嗜水气单胞菌24 h的蟹死亡率分别可达62.45%和100%,低氧胁迫12 h使血淋巴中血蓝蛋白浓度、血细胞数量、组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活性显著升高(P<0.05),胁迫至第24小时有下降趋势;乳酸(LD)和丙二醛(MDA)浓度在低氧胁迫12~24 h持续上升。2)饲料中添加适量(0.1~0.4 mg·kg^(−1))纳米硒可显著降低低氧胁迫下蟹死亡率和低氧胁迫下嗜水气单胞菌的致死率(P<0.05),显著提高低氧胁迫下血蓝蛋白浓度和血细胞数量以及抗氧化酶(SOD、CAT、GSH-Px)活性,降低LD和MDA浓度(P<0.05);添加0.8~1.6 mg·kg^(−1)纳米硒加剧了低氧胁迫损伤。结果表明饲料中添加适量纳米硒可改善低氧胁迫下中华绒螯蟹的免疫功能和抗氧化能力,且添加水平以0.2 mg·kg^(−1)为宜。

Hypoxia stress will weaken the immune function and antioxidant capacity of Eriocheir sinensis.In order to reveal the immune protection and anti-oxidation regulation mechanism of nanometer selenium(nano-Se)on E.sinensis under hypoxia stress,we had fed E.sinensis with different doses of nano-Se(0,0.1,0.2,0.4,0.8 and 1.6 mg·kg^(−1))in basic diets for 90 d.After the feeding,we conducted a hypoxia stress test and injected Aeromonas hydrophila under hypoxia stress.The results show that:1)The mortality of E.sinensis under hypoxia stress for 24 h and that infected with A.hydrophila under hypoxia stress reached 62.45%and 100%,respectively.The levels of hemocyanin and the hemocyte count in crab hemolymph,and the activities of superoxide dismutase(SOD),catalase(CAT),and glutathione peroxidase(GSH-Px)in crab tissues increased significantly under hypoxia stress for 12 h(P<0.05),as well as there was a decreasing trend under stress to 24 h.The contents of lactic acid(LD)and malondialdehyde(MDA)continued to rise from 12 to 24 h under hypoxia stress.2)Appropriate addition amount(0.1−0.4 mg·kg^(−1))of nano-Se reduced the mortality of E.sinensis significantly and the lethality of A.hydrophila under hypoxia stress(P<0.05),increasing the levels of hemocyanin,the hemocyte count and the activities of antioxidant enzymes(SOD,CAT,GSH-Px)under hypoxia stress significantly,but decreasing the contents of LD and MDA(P<0.05).The addition of 0.8−1.6 mg·kg^(−1)nano-Se had aggravated hypoxia stress injury.These results indicate that appropriate addition of nano-Se to the diets can improve the decrease of immune response and antioxidant ability of E.sinensis under hypoxia stress,and the optimal dose of nano-Se in basal diets is 0.2 mg·kg^(−1).