慢性氨氮胁迫对史氏鲟幼鱼生长及其肝脏抗氧化、免疫指标的影响

该研究以史氏鲟(Acipenser schrenckii)幼鱼为实验对象,在实验室内营造了0.01 mg·L^?1(对照组)、0.50 mg·L^?1(低浓度组)、1.00 mg·L^?1(中浓度组)、2.00 mg·L^?1(中高浓度组)和4.00 mg·L^?1(高浓度组)5个氨氮浓度组,对史氏鲟胁迫养殖60 d后取样测定其生长、抗氧化和免疫功能的相关指标,初步揭示史氏鲟幼鱼对慢性氨氮胁迫的生理响应。结果显示,随氨氮浓度升高,史氏鲟幼鱼的增重率(WGR)、特定生长率(SGR)、脏体比(VSI)和肝体比(HSI)均显著下降(P<0.05),但肥满度(CF)无显著变化。在抗氧化指标中,随着氨氮浓度的增加,肝脏超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、总抗氧化能力(T-AOC)活性和谷胱甘肽(GSH)含量呈下降趋势,丙二醛(MDA)含量呈上升趋势。免疫指标中,肝脏溶菌酶(LZM)活性和免疫球蛋白M(IgM)含量受氨氮胁迫影响显著(P<0.05)。结果表明,慢性氨氮胁迫显著抑制了史氏鲟幼鱼的生长,降低了鱼体的抗氧化能力和免疫能力。建议在史氏鲟实际养殖过程中,养殖水体中氨氮质量浓度应控制在≤0.5 mg·L^?1,以避免其对史氏鲟造成损伤。

Effects of chronic ammonia stress on growth,antioxidative and immunity indices in liver of juvenile Acipenser schrenckii

To preliminarily reveal the physiological response of juvenile Acipenser schrenckii to chronic ammonia-nitrogen stress,we exposed the juveniles to different ammonia nitrogen concentrations(0.01,0.5,1.0,2.0 and 4.0 mg·L^?1)for 60 d,and investigated their growth,antioxidative and immunity indices.The results show that the weight gain rate(WGR),specific growth rate(SGR),viserosomatic index(VSI)and hepatosomatic index(HSI)of the juveniles decreased significantly with the increase of ammonia concentration(P<0.05).However,there was no significant change in condition factor(CF).Among the antioxidative indexes,the superoxide dismutase(SOD),catalase(CAT),total antioxidant capacity(T-AOC)activity and glutathione(GSH)content in liver decreased gradually with the increase of ammonia concentration,while malondialdehyde(MDA)content increased gradually.Among the immune indices,lysozyme(LZM)activity and immunoglobulin M(IgM)content in the liver decreased significantly(P<0.05).The results suggest that the chronic ammonia stress inhibits the growth,antioxidative and immunity capacity of the juveniles significantly.Thus,in the actual breeding process of A.schrenckii,the ammonia concentration in water should be controlled at≤0.5 mg·L^?1 to avoid the adverse effects of ammonia stress.