Yu Haibo, Deng Wei, Zhang Dongdong, Gao Yao, Yang Zhou, Shi Xiaochen, Sun Jian, Zhou Jishu, Ji Hong
College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China.
School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn 36849, USA.
Fish Shellfish Immunol. 2017 Jul;66:50-61. doi: 10.1016/j.fsi.2017.04.027. Epub 2017 May 3.
Onychostoma macrolepis has becoming an endangered fish species in China, which population gradually declined in the past few decades due to the changing environment including elevated water temperature resulted from adverse weather events. The present study determined antioxidant defenses of O. macrolepis in response to thermal stress, aiming to understand the role of antioxidant system in adaptation of thermal stress for O. macrolepis. Experimental fish which were acclimated at 24 °C were stressed at 30 °C for 0 h, 1 h, 3 h, 6 h, 12 h, 24 h and 48 h, respectively. Change in mRNA expression of Cu/Zn superoxide dismutase (Cu/Zn-SOD) and catalase (CAT) and activity of SOD and CAT of the experimental fish with different stress time were determined. We cloned the full-length cDNA of Cu/Zn-SOD and CAT by means of RACE method, and analyzed their molecular characterization and tissue distribution. We discovered that the mRNA expression of the Cu/Zn-SOD in heart, liver, spleen, gill, intestine and the CAT in heart, liver, spleen, kidney, intestine and muscle of O. macrolepis significantly increased when water temperature increased from 24 °C to 30 °C, indicating a sensitive response of mRNA expression of Cu/Zn-SOD and CAT to the thermal stress. Moreover, the mRNA expression of the Cu/Zn-SOD and CAT were varied in different tissues, indicating different sensitivity of the tissues in response to thermal stress. Activity of the SOD in serum of O. macrolepis gradually increased from 1 h to 12 h sampling time, but significantly decreased at 24 h sampling time, compared to that of 0 h sampling time. And activity of the CAT in serum of O. macrolepis significantly decreased from 1 h to 12 h sampling time, and did not changed significantly at 24 h and 48 h sampling time, compared to that of 0 h sampling time. As such, MDA contents in the serum of O. macrolepis significantly decreased from 1 h to 6 h sampling time, but significantly increased at 12 h and 24 h sampling time, compared to that of 0 h sampling time. In summary, antioxidant system of the O. macrolepis can quickly response to short term thermal stress at 30 °C in form of both the mRNA expression of Cu/Zn-SOD and CAT and the activity of SOD and CAT, and consequently enhance the antioxidant defenses of O. macrolepis. However, thermal stress at 30 °C for 12 h-24 h seems to lead to oxidative damage of the O. macrolepis.
中华倒刺鲃已成为中国一种濒危鱼类，在过去几十年里，由于环境变化，包括恶劣天气事件导致水温升高，其种群数量逐渐减少。本研究测定了中华倒刺鲃在热应激下的抗氧化防御能力，旨在了解抗氧化系统在中华倒刺鲃适应热应激中的作用。将在24℃驯化的实验鱼分别在30℃下应激0小时、1小时、3小时、6小时、12小时、24小时和48小时。测定了不同应激时间下实验鱼铜/锌超氧化物歧化酶（Cu/Zn-SOD）和过氧化氢酶（CAT）的mRNA表达变化以及SOD和CAT的活性。我们通过RACE方法克隆了Cu/Zn-SOD和CAT的全长cDNA，并分析了它们的分子特征和组织分布。我们发现，当水温从24℃升高到30℃时，中华倒刺鲃心脏、肝脏、脾脏、鳃、肠道中的Cu/Zn-SOD以及心脏、肝脏、脾脏、肾脏、肠道和肌肉中的CAT的mRNA表达显著增加，表明Cu/Zn-SOD和CAT的mRNA表达对热应激反应敏感。此外，Cu/Zn-SOD和CAT的mRNA表达在不同组织中有所不同，表明各组织对热应激的敏感性不同。与0小时采样时间相比，中华倒刺鲃血清中SOD的活性在1小时至12小时采样时间逐渐增加，但在24小时采样时间显著下降。与0小时采样时间相比，中华倒刺鲃血清中CAT的活性在1小时至12小时采样时间显著下降，在24小时和48小时采样时间没有显著变化。因此，与0小时采样时间相比，中华倒刺鲃血清中MDA含量在1小时至6小时采样时间显著下降，但在12小时和24小时采样时间显著增加。综上所述，中华倒刺鲃的抗氧化系统可以通过Cu/Zn-SOD和CAT的mRNA表达以及SOD和CAT的活性，快速响应30℃的短期热应激，从而增强中华倒刺鲃的抗氧化防御能力。然而，30℃下12小时至24小时的热应激似乎会导致中华倒刺鲃的氧化损伤。
