短期低盐度胁迫对驼背鲈(♀)×鞍带石斑鱼(♂)杂交子代幼鱼抗氧化及消化生理的影响

Effects of short-term salinity stress on antioxidant and digestive physiology of hybrid progeny(Cromilepptes altivelis ♀ × Epinephelus lanceolatus ♂)

为探讨在不同程度的盐度降低下对驼背鲈(Cromilepptes altivelis♀)与鞍带石斑鱼(Epinephelus lanceolatus♂)的杂交品种(鼠龙斑幼鱼)摄食、抗氧化和消化生理的影响,本实验设置盐度突变组:5×10^(–3)、10×10^(–3)、15×10^(–3)、20×10^(–3)、25×10^(–3)、30×10^(–3)(对照组);盐度渐变组(每天盐度降低5×10^(–3))。在第0、3、7天时分别取样,测定血清和肝脏中的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、丙二醛(MDA)活力;胃组织中的胃蛋白酶、肠道中的脂肪酶、淀粉酶活性。结果表明:盐度突变组中,盐度降低幅度越大对酶活性的影响越大,尤其5×10^(–3)~15×10^(–3),3种抗氧化性酶活性在肝脏中的变化趋势相似,均呈显著升高再降低的趋势,血清中的SOD、CAT在第3、7天活性相似,均显著高于其他同时期各组,MDA在第7天显著升高;3种消化酶活性均显著下降,盐度越低,下降幅度越显著;其他各组的抗氧化性酶和消化酶活性与对照组相比无明显差异。盐度突变组各组的摄食量均呈下降趋势,尤其5×10^(–3)组最低。盐度渐变组SOD、CAT活性呈持续上升趋势,MDA先上升再下降,胃蛋白酶与脂肪酶活性均是呈先上升再下降的趋势,淀粉酶持续下降;其摄食量下降后又恢复至胁迫前。综上,鼠龙斑对盐度的适应范围较广,当盐度突变为较低的水平(<15×10^(–3))时,对鼠龙斑的抗氧化性及消化生理的影响较大,随着胁迫时间延长可能对鱼体肝脏抗氧化系统具有损害作用,从而影响其生长,因此在实际过程中可通过逐渐降低盐度的方式对鼠龙斑进行驯养,以达到降低应激伤害的作用。

This study investigated the effects of different salinities on the feeding, antioxidant, and digestive physi-ology of the hybrid cultivars Cromilepptes altivelis♀ and Epinephelus lanceolatus♂. Five salinity mutation groups, 5×10^-3, 10×10^-3, 15×10^-3, 20×10^-3, 25×10^-3, 30×10^-3, and a salinity gradient group （salinity decrease by 5×10^-3 per day） were set up. A salinity of 30×10^-3 was used as the control group. The activities of superoxide dismutase （SOD）, catalase （CAT）, and malondialdehyde （MDA） in serum and liver; those of lipase and amylase in the intestinal canal; and the pepsin activity in the stomach tissue were measured at 0, 3, and 7 d, respectively. The results showed that the effects of salinity on the enzyme activities increased with decreasing salinity in the salinity mutation groups, especially in the 5×10^-3 to 15×10^-3 group. The levels of the three antioxidant enzymes in the liver showed similar changes, i.e., they were first increased and then decreased. The activities of SOD and CAT in the serum were sig-nificantly higher than those in other groups on the 3rd and 7th day, and the activity of MDA was significantly in-creased on the 7th day. The activities of the three digestive enzymes were significantly decreased, with a lower sa-linity causing a more significant decrease. There was no significant change in the activities of the antioxidant and digestive enzymes between other groups and the control group. A decreasing trend in food intake was observed in the salinity mutation groups, with the lowest food intake level being observed in the 5×10^-3 group. The activities of SOD and CAT increased gradually, while the activity of MDA increased at first and then decreased in the salinity gradient group. The activities of pepsin and lipase increased initially, whereas the activity of amylase decreased continuously. The food intake decreased initially and then returned to the level of the control group. In summary, juvenile mussaurus spot can adapt to a wide range of salinity. However, a low salinity level （〈15×10^-3） was found to have a significant effect on the antioxidant activity and the digestive physiology of juvenile mussaurus spot. In addition, there may be a damaging effect on the antioxidant system of the liver, including the growth of the fish. Therefore, decreasing the salinity gradually can help in achieving the required conditions, which can reduce the adverse stress response during salinity acclimation.