盐度骤降对点篮子鱼存活率及肝脏抗氧化酶活性的影响

The Effects of Ambient Salinity Decrement on Survival and the Activity of Antioxidant Enzymes in Livers of Siganus Guttatus

水体盐度是影响鱼类生长的重要环境因素之一,为了解急性盐度胁迫对点篮子鱼(Siganus guttatus)存活率及肝脏超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-PX)活性的影响,设定盐度30(对照)、盐度20、盐度10、盐度5和淡水5个盐度梯度进行试验.结果表明:96 h内各组死亡率均为0%,182 h淡水组死亡率为100%,其余4组死亡率为0%.酶活性检测结果显示:将点篮子鱼直接放入盐度10和盐度20的水体中,SOD、CAT和GSH-PX活性虽有一定程度的升高,但与对照组无显著性差异(P>0.05).直接放入盐度5的水体中,SOD酶活性与对照组无显著性差异,而CAT和GSH-PX活性与对照组有显著性差异,但在24 h时均恢复到对照组水平.直接放入淡水中,3种酶活性均在3 h时达到最高,与对照组有显著性差异,SOD活性在12 h时恢复到对照组水平,CAT活性在48 h时恢复到对照组水平,GSH-PX活性在48 h时与对照组仍有显著性差异(P<0.05),96 h时仍高于对照组,但无显著性差异(P>0.05).结果表明:点篮子鱼对低盐的耐受力比较强,在盐度突然改变时能通过调节自身的抗氧化酶活力来清除体内多余的自由基,但对淡水环境耐受力比较差.

Effects of ambient salinity decrement on survival and the activity of three antioxidant enzymes（SOD,CAT,GSH-PX） in livers of Siganus guttatus were studied.The rabbitfish（（39.41±12.80）g） were reared in different salinity of 30（the control group）,20,10,5and the fresh water.The mortality of each group during 96h was 0%.But the mortality of the rabbitfish reared in the fresh water was 100% after 186h while the others were 0%.In group of salinity 10 and 20,the activity of the three antioxidant enzymes was higher than that in control group,but there was no significant difference（P〉0.05）.In group of salinity 5,there was no significant difference with the control group of the activity of SOD.But the activities of CAT and GSH-PX was significant higher than that in the control group after 3h,then decreased and tended to be stable after 24h.In group of the fresh water,the activity of the three enzymes peaked at 3h,and it was significant higher than that in the control group.The activity of SOD tended to stable after 12h while CAT was after 48h.But the activity of GSH-PX was still significant higher than that in the control group until 96h.It was still higher than that in the control group in 96h,but there was no significant difference.The results showed that the rabbitfish had high resistance against changes of salinity,and could regulate the activity of the antioxidant enzymes remove the excessive free radial.But they had low resistance against the fresh water.