急性高盐胁迫对绿鳍马面鲀幼鱼存活、鳃组织及肝脏抗氧化能力的影响

Effects of acute high salinity stress on survival,gill tissue and hepatic antioxidant capacity of juvenile Thamnaconus septentrionalis

为探究绿鳍马面鲀(Thamnaconus septentrionalis)在高盐胁迫下的适应能力和生理生化调控机能,设置不同盐度条件,对绿鳍马面鲀幼鱼进行96 h的胁迫实验,比较研究绿鳍马面鲀幼鱼在不同盐度下的存活率、鳃组织结构、Na^(+)/K^(+)-ATP酶活性以及肝脏抗氧化能力。结果显示,在盐度30~35范围内,绿鳍马面鲀幼鱼的存活没有受到盐度变化影响,而盐度40以上对幼鱼存活具有显著性影响(P<0.05),幼鱼在胁迫24、48、72、96 h所对应的高盐半致死盐度LC50分别为47.062、46.279、45.886和45.736。高盐胁迫下,与对照组相比,盐度35组中绿鳍马面鲀幼鱼的鳃组织结构无显著变化,而盐度40和45组中幼鱼的鳃组织出现了不同程度的鳃小片弯曲变粗、萎缩变短、排列紊乱、基部增生、融合以及细胞空泡化等现象。除了丙二醛含量指标,3个盐度组的Na^(+)/K^(+)-ATP酶活性和肝脏抗氧化能力在各胁迫时间的值均显著高于对照组(P<0.05),且大多在胁迫时间48 h时达最大值,72 h降低。研究表明,在高盐胁迫下,绿鳍马面鲀幼鱼机体会产生一系列应激反应,其鳃组织结构会做出不同程度的适应性变化,且幼鱼存活率、鳃丝Na^(+)/K^(+)-ATP酶活性及肝脏抗氧化能力均有明显变化,绿鳍马面鲀幼鱼可适应的盐度为35,盐度40以上环境会对绿鳍马面鲀幼鱼的存活和生长产生负面影响。研究结果可为绿鳍马面鲀的人工海水养殖和耐盐品系的选育提供基础数据和理论依据。

To investigate the adaptive ability and physiological and biochemical regulation of Thamnaconus septentrionalis under high salinity stress,and to compare the survival,gill tissue structure,Na^(+)/K^(+)ATPase activity,and hepatic antioxidant capacity of juveniles in different salinity groups,salinity treatment groups were set up,and juveniles subjected to 96 h of highsalinity stress were studied.The study can provide basic data and theoretical basis for the production of artificial seawater aquaculture of Thamnaconus septentrionalis and the selection and breeding of salttolerant strains.There was no mortality of juvenile Thamnaconus septentrionalis in salinity group 35;juvenile mortality began to occur in salinity groups 40,45 and 50 at 24 h of stress;at 96 h,the mortality rates of salinity groups 40,45 and 50 were 10%,13.33%and 100%,respectively,and the mortality rates of salinity groups 45 and 50 were significantly higher than that of salinity group 40(P<0.05).The LC50 of juvenile Thamnaconus septentrionalis were 47.062,46.279,45.886,and 45.736 at 24,48,72,96 h,respectively,which showed a decreasing trend in LC50 with the increase of stress time.Changes in gill filament structure were not obvious in the salinity 35 group compared with the control group.In salinity group 40,the secondary lamellas were bent,the epithelial cells were severely edematous,the cytoplasm was hyaline and more ruptured,the cells appeared to be vacuolated,the number of mitochondriarich cells of gill filaments as a whole increased,the bases of the secondary lamellas were enlarged obviously,and the fusion phenomenon appeared in the neighboring secondary lamellas.In salinity group 45,secondary lamellas were significantly shortened,secondary lamellas flat epithelial cells were severely ruptured and detached,the outline was blurred,cell vacuolization increased,mitochondriarich cells filled the secondary lamellas,and the fusion of secondary lamellas increased gradually with the prolongation of the stress time.Except for the content of MDA,Na^(+)/K^(+)ATPase activity and hepatic antioxidant capacity of the three treatment groups were significantly higher than that of the control at all time points(P<0.05),and most reached the peak at 48 h,then decreased at 72 h.The results showed that high salinity stress had a significant effect on the survival,gill tissue structure,Na^(+)/K^(+)ATPase activity,and liver antioxidant capacity of juvenile Thamnaconus septentrionalis.The larvae of Thamnaconus septentrionalis have some selfregulation ability under high salinity stress,but excessive salinity will cause damage to the larval organism and reduce the resistance of the larvae,which will ultimately lead to the death of the larvae.The normal growth salinity of juvenile Thamnaconus septentrionalis can be up to 35,and salinities above 40 will significantly affect the survival and growth of juveniles.