低温胁迫对美洲鲥抗氧化状态及应激相关基因表达的影响

Influences of low temperature stress on antioxidant status and expression of stress-related genes of American shad, Alosa sapidissima

为了探究低温对美洲鲥(Alosa sapidissima)损伤的分子机制,本研究首先采用缓慢变温的方法诱导低温胁迫并检测了低温胁迫下肝脏抗氧化状态和肌肉组织应激相关基因的表达水平。结果表明,低温使肝脏SOD活性和总抗氧化能力(T-AOC)降低,GSH-PX活性表现为先升高(处理0h时)、后降低(处理24h、48h)的变化趋势,CAT活性和MDA含量并未出现显著变化;肌肉hsp70 mRNA表达量升高,hsp90 mRNA表达量具有先升高(处理0h时)、后恢复初始水平的趋势,ybx1 mRNA表达量下降(处理48h)。综上,低温胁迫降低了美洲鲥的抗氧化能力,进而导致内环境稳态失去原有平衡。抗氧化酶SOD和GSH-PX是美洲鲥抵抗低温损伤的关键分子,而热休克蛋白HSP70和HSP90在细胞防御过程中有重要作用。本研究通过探究低温条件下抗氧化状态和应激相关基因表达的变化,为美洲鲥的推广养殖和低温机体抗损伤调节机制研究提供参考。

The American shad(Alosa sapidissima) is an upstream amphihaline migratory fish species with high economic and ecologic values. As a substitution of Tenualosa reevesii, it was introduced into China at the beginning of the 21st century. With the enlargement of the cultivation scale in China, temperature-induced problems become more and more serious, which have resulted in mass mortality. However, we still do not know the molecular mechanisms of temperature-induced damage in American shad. To investigate the molecular mechanism of temperature-induced injury of American shad, in this study, the antioxidant status and stress-related genes expression under low temperature stress were analyzed by slowly changing the temperature. It turned out that low temperature stress reduced the activity of hepatic SOD and total antioxidant capacity(T-AOC). Under low temperature stress, GSH-PX activity first increased(0 h), but decreased with the extension of treatment time(24 h and 48 h). There was no significant change in hepatic CAT activity and MDA content. The muscular hsp70 mRNA abundance increased after low temperature treatment(12 h and 48 h) as well as hsp90 mRNA abundance increased first(0 h) and then recovered to the initial level. In American shad, ybx1 mRNA abundance decreased at 48 h. However, neither hepatic CAT activity nor MDA content had significant change under low temperature stress. In summary, low temperature stress caused homeostasis imbalance via reducing hepatic antioxidant ability of American shad. In American shad, antioxidant enzymes SOD and GSH-PX are key members that resist oxidative damage at low temperature, while HSP90 and HSP70 play important roles in cell defense one after the other. This study explored the changes of antioxidant system and stress-related genes expression under low temperature, and provided references for the promotion and the mechanism of anti-injury regulation of low temperature organisms.