Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, Qinghai, China.
State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, Qinghai, China.
J Therm Biol. 2023 Aug;116:103650. doi: 10.1016/j.jtherbio.2023.103650. Epub 2023 Jul 13.
The Qinghai-Tibet Plateau is undergoing a wet-warming transition, which could affect the survival of the native fish. However, the tolerance and physiological response to thermal stress is rarely studied in Gymnocypris przewalskii, a rare native fish in the Tibetan plateau. In this study, first, we detected the thermal tolerance of five groups of six-month G. przewalskii which acclimated at 8, 12, 16, 20, and 24 °C for two weeks, respectively, by critical thermal methodology. Then, through heat challenge, we detected the metabolites, key enzyme activities, and gene expressions involved in metabolism and antioxidant in the hepatopancreas when the temperatures increased from 16 °C to 18, 20, 22, 24, 26, and 28 °C for 12 h, respectively. The results showed that although the fish are sensitive to high temperatures, the quick acclimation at mild high temperatures could significantly improve the tolerance to acute high-temperature stress in juvenile G. przewalskii. During the heat challenge study, blood glucose significantly increased at heat stress (P < 0.05). At the same time, total cholesterol (TC), triglyceride (TG), and free fatty acid (FFA) significantly decreased when the temperature rose continuously to 20 °C. Metabolic enzyme activities of carnitine palmityl transferase I (CPT-Ⅰ), acetyl-CoA carboxylase (ACC), and fatty acid synthase (FAS) significantly decreased at 20 °C (P < 0.05). Superoxide dismutase (SOD) and antioxidant capacity (T-AOC) significantly increased at 20 °C (P < 0.05). The relative transcript levels of genes involved in antioxidant and glycolysis/gluconeogenesis were markedly higher than the control at 20-26 °C (P < 0.05). The genes involved in fatty acid biosynthesis or metabolism showed different expression patterns under heat stress. Heat shock protein 70 (Hsp70) and Hsp90 were significantly higher than the control at 18 °C and 26 °C, respectively. These results confirmed the prediction that G. przewalskii is sensitive to high temperatures, so conservation efforts should pay more attention to the warming damage.
青藏高原正在经历暖湿化转变，这可能会影响到当地鱼类的生存。然而，对于青藏高原特有的珍稀鱼类普氏原羚（Gymnocypris przewalskii）来说，其对热应激的耐受能力和生理反应却鲜有人研究。在这项研究中，我们首先采用临界热方法检测了分别在 8、12、16、20 和 24°C 下适应两周的五组 6 个月大的普氏原羚的热耐受能力。然后，通过热激实验，我们检测了当温度从 16°C 升高到 18、20、22、24、26 和 28°C 并持续 12 小时时，普氏原羚肝胰腺中涉及代谢和抗氧化的代谢物、关键酶活性和基因表达情况。结果表明，尽管鱼类对高温敏感，但在温和的高温下快速适应可以显著提高幼体普氏原羚对急性高温胁迫的耐受能力。在热激实验中，血糖在热应激时显著升高（P<0.05）。同时，当温度连续升高到 20°C 时，总胆固醇（TC）、甘油三酯（TG）和游离脂肪酸（FFA）显著降低。肉碱棕榈酰转移酶 I（CPT-Ⅰ）、乙酰辅酶 A 羧化酶（ACC）和脂肪酸合酶（FAS）的代谢酶活性在 20°C 时显著降低（P<0.05）。超氧化物歧化酶（SOD）和抗氧化能力（T-AOC）在 20°C 时显著增加（P<0.05）。在 20-26°C 时，与抗氧化和糖异生/糖酵解相关的基因的相对转录水平明显高于对照（P<0.05）。脂肪酸生物合成或代谢相关基因表现出不同的表达模式。热休克蛋白 70（Hsp70）和 Hsp90 在 18°C 和 26°C 时均显著高于对照。这些结果证实了普氏原羚对高温敏感的预测，因此保护工作应更加关注升温造成的损害。
