饲料中添加纳米氧化铈对氨氮与嗜水气单胞菌胁迫下中华绒螯蟹的保护效应

Protective effects of addition of nano cerium oxide in diets on Eriocheir sinensis under ammonia-nitrogen and Aeromonas hydrophila stresses

为探索中华绒螯蟹(Eriocheir sinensis)应对不良水环境胁迫的作用机制,该研究通过在饲料中添加纳米氧化铈(nCeO_(2)),探究其对氨氮(NH_(3)-N)与嗜水气单胞菌(Aeromonas hydrophila)胁迫下中华绒螯蟹免疫力和抗氧化能力的影响。用含不同剂量nCeO_(2)(0、0.2、0.4、0.8、1.6、3.2、6.4和12.8 mg·kg^(−1))的饲料连续饲喂中华绒螯蟹90 d后进行NH_(3)-N与嗜水气单胞菌胁迫实验。结果显示:1)NH_(3)-N单胁迫和NH_(3)-N与嗜水气单胞菌双胁迫(下文简称“双胁迫”)均显著降低了中华绒螯蟹的成活率(P<0.01),酸性磷酸酶(ACP)、碱性磷酸酶(AKP)和溶菌酶(LZM)活性均显著上升(P<0.01或P<0.05),超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性均显著下降(P<0.01),丙二醛(MDA)显著上升(P<0.01或P<0.05);2)适量的nCeO_(2)可显著提升NH_(3)-N单胁迫和双胁迫下中华绒螯蟹的成活率(P<0.01或P<0.05),增强其SOD和CAT活性(P<0.01),降低MDA浓度(P<0.01或P<0.05),进一步提升LZM活性(P<0.01),但ACP和AKP活性仅在双胁迫下进一步增强(P<0.01)。综上,适量添加nCeO_(2)可改善NH_(3)-N单胁迫和双胁迫所造成的中华绒螯蟹成活率和抗氧化能力下降,提高其免疫酶活性,且添加0.8、1.6 mg·kg^(−1)nCeO_(2)分别对单胁迫和双胁迫下的蟹体保护作用最明显。

To explore the mechanism of Chinese mitten crabs(Eriocheir sinensis)dealing with adverse water environmental stresses,we studied the effects of nano cerium oxide(nCeO_(2))on the immunity and antioxidant capacity of the crabs under ammonia-nitrogen and Aeromonas hydrophila stresses.The crabs were continuously fed with diets supplemented with different doses of nCeO_(2)(0,0.2,0.4,0.8,1.6,3.2,6.4 and 12.8 mg·kg^(−1))for 90 d,then the ammonia-nitrogen and A.hydrophila stress tests were conducted.The results show that:1)Both the single ammonia-nitrogen stress and dual stresses of ammonia-nitrogen and A.hydrophila(henceforth called"dual stress")decreased the survival rates of the crabs significantly(P<0.01);the activities of acid phosphatase(ACP),alkaline phosphatase(AKP)and lysosome(LZM)increased(P<0.01 or P<0.05);the activities of superoxide dismutase(SOD)and catalase(CAT)decreased significantly(P<0.01),while the concentration of malondialdehyde(MDA)increased(P<0.01 or P<0.05);2)Suitable nCeO_(2)dose could enhance the survival rates of crabs under the single ammonia-nitrogen stress and dual stress(P<0.01 or P<0.05),increase the activities of SOD and CAT significantly(P<0.01),decrease the concentration of MDA(P<0.01 or P<0.05),further increase the activity of LZM(P<0.01),but the activities of ACP and AKP only increased under dual stress(P<0.01).Above all,suitable supplementation of nCeO_(2)can ameliorate the decline of survival rates and antioxidant capacity of E.sinensis under the the single ammonia-nitrogen stress and dual stress,and increase the im-munity enzyme activities.The suitable nCeO_(2)supplementation doses for protecting crabs are 0.8 and 1.6 mg·kg^(−1) under single and dual stress,respectively.