急性高温胁迫后二倍体和三倍体虹鳟抗氧化能力差异比较研究

Comparison Studies of Antioxidant Enzymes between Diploid and Triploid Rainbow Trout in Acute High Temperature Stress

摘要: 本文以二倍体(2n)和三倍体(3n)虹鳟幼鱼为实验材料，选取体长、体重相近，无病无伤，体格健壮的实验鱼，在15℃水温中暂养2周后，直接放到23℃ ± 0.5℃高温水中，观测急性温度胁迫对虹鳟幼鱼的总超氧化物歧化酶、过氧化氢酶的活性的影响，以及对总超氧化物歧化酶、过氧化氢酶基因相对表达量的影响。结果表明：在48 h高温胁迫过程中，实验鱼肌肉、内脏团组织的SOD、CAT活性均呈现先上升后下降趋势，三倍体虹鳟肌肉组织中SOD活性在24h显著高于其他时间点(P < 0.05)；二倍体虹鳟肌肉组织中CAT活性在24 h出现峰值(P < 0.05)，三倍体虹鳟其他时间点则显著低于0 h (P < 0.05)；在内脏团组织中，二倍体虹鳟在12 h出现峰值(P < 0.05)，三倍体虹鳟则呈现整体高水平，差异不显著(P > 0.05)；在肝脏组织中，SOD1、CAT的相对表达量呈现相似结果，但是二倍体虹鳟在6 h出现峰值(P < 0.05)，三倍体虹鳟则在24 h出现峰值(P < 0.05)，在SOD2的相对表达量方面，二倍体虹鳟与三倍体虹鳟结果一致，都在6 h处出现峰值。在48 h恢复常温15℃水温之后，实验鱼肌肉组织中SOD、CAT活性变化不显著(P > 0.05)，在肝脏组织中，SOD1、CAT的相对表达量结果相似，都是二倍体虹鳟变化不显著(P > 0.05)，三倍体虹鳟在72 h处有显著的升高，96 h降低至与48 h相同的相对表达量。本研究表明不同倍性的虹鳟在相同的温度胁迫下抗氧化能力存在差异。

Abstract: In this study, diploid (2n) and triploid (3n) rainbow trout juveniles with similar body length and weight, and healthy with no disease or injury were selected as experimental materials. After tem-porary rearing for 2 weeks at 15˚C water temperature, they were transferred directly to the water with high temperature of 23˚C ± 0.5˚C. The purpose was to investigate the effects of acute temper-ature stress on the survival rate, SOD, CAT enzyme activity and relative expression of SOD and CAT genes in juvenile rainbow trout. The results showed that the activity of SOD and CAT in the muscle and visceral tissues of the diploid and triploid rainbow trout increased firstly and then decreased during the 48 h high temperature challenging period. The activity of SOD in the muscle tissue of triploid rainbow trout was significantly higher than other time points at 24 h. (P < 0.05); CAT ac-tivity in diploid rainbow trout muscle tissue peaked at 24 h (P < 0.05). At other time points of triploid rainbow trout, the CAT enzyme activity is lower than that at 0 h. In the visceral mass, the CAT enzyme activity of diploid rainbow trout appeared peak at 12 h (P < 0.05). The triploid rainbow trout showed an overall high expression level, and the difference was not significant (P > 0.05). In liver tissue, the SOD1 and CAT exhibited similar expression pattern, but the peak of diploid rainbow trout appeared at 6 h (P < 0.05), and the peak of triploid rainbow trout appeared at 24 h (P < 0.05). In terms of the relative expression of SOD2, the diploid rainbow trout was consistent with the triploid rainbow trout, which peaked at 6 h. The activity of SOD and CAT in the muscle tissue of the diploid and triploid rainbow trout was not significantly changed when the water temperature recovered to 15˚C after 48 h (P > 0.05). In the liver tissue, the relative expression profile of SOD1 and CAT was similar, that there was no significant change for all diploid rainbow trout. For the triploid rainbow trout, the expression level increased significantly at 72 h, and at 96 h, it decreased to the same level as 48 h. This study shows that different ploidy rainbow trout has the different antioxidant capacity under the same temperature stress.