溶氧水平对梭鱼幼鱼能量代谢与氧化应激的影响

为分析低氧胁迫对梭鱼（Liza haematocheila）幼鱼能量代谢与氧化应激的影响,选择体重为6～10g的梭鱼,在溶氧水平从7.18 mg/L降至0.60mg/L过程中测定其耗氧率和排氨率,计算幼鱼相对应的氧氮原子比（O∶ 2 N）;又在溶氧水平大于6.0mg/L、4.5 mg/L、3.0 mg/L、1.5 mg/L、0.5 mg/L时,分别测定幼鱼肌肉和肝脏组织中的乳酸（LD）含量、过氧化物歧化酶（SOD）活力、总抗氧化能力（T-AOC）、抗超氧阴离子活力（ASOR）、丙二醛（MDA）含量.结果显示,随着溶氧水平的下降,梭鱼的耗氧率和排氨率总体呈降低趋势,氧氮原子的比值在溶氧水平3.23～1.92 mg/L时达到最大,在溶氧水平1.03～1.60 mg/L时达到最小;溶氧水平为6.15mg/L时,肝脏中LD、SOD、T-AOC、ASOR、MDA均显著大于其它溶氧水平下的相应指标（P＜0.05）.溶氧水平下降过程中,肌肉组织中的SOD、MDA、TAOC差异不显著（P＞0.05）,溶氧水平在0.5 mg/L时,LD显著高于其它组（P＜0.05）.这表明,梭鱼能通过降低耗氧率和排氨率、改变代谢底物和提高肌肉、肝脏组织无氧代谢能力等方式,达到新陈代谢的平衡,以适应低氧生活.

Energy Metabolism and Oxidative Stress of Juvenile Liza haematocheila as Dissolved Oxygen Decline

To study the effect of hypoxia stress on the energy metabolism and oxidative metabolism of juvenile Liza haematocheila,the oxygen consumption rate and amonia excretion rate of experimental fish were determined and the oxygen-nitrogen ratio was calculated while the dissolved oxygen level ranged from 7.18 to 0.60 mg/L.The lactic acid（LD）,superoxide dismutase （SOD）,total antioxidant capability （T-A OC）,anti-superoxide anion （ASOR） and malondiadehyde （MDA） in the musler and liver were measured when the dissolved oxygen level were above 6.0 mg/L,4.5 mg/L,3.0 mg/L,1.5 mg/L and 0.5 mg/L,respectively.The results showed that the oxygen consumption rate and amonia excretion rate of juvenile fish presented a downward trend.The oxygen-nitrogen ratio reached the maximum when the dissolved oxygen level was 3.23～ 1.92 mg/L,and the minimum when the dissolved oxygen level was 1.03～1.60 mg/L.The LD,SOD,T-AOC,ASOR and MDA of liver were significantly greater at the dis solved oxygen level of 6.15 mg/L than that at other dissolved oxygen levels.The SOD,MDA and TAOC of muscle had no direct correlation with dissolved oxygen （P 〉0.05）,and LD significantly higher than other groups when the dissolved oxygen level was 0.5 mg/L.This study suggested that juvenile Liza haematocheila could adapt hypoxia environment by reducing oxygen consumption rate and amonia excretion rate,changing metabolic substrate and improving anaerobic metabolism capacity of muscle and liver.