Hypoxia is an unfavorable environmental condition that produces diverse negative effects in fish. High-density cultures of Epinephelus coioides are more likely to experience hypoxic conditions than those in natural environments. To assess the effects of hypoxia on E. coioides, we examined the related enzyme activities and gene expression after 48 h of hypoxia and 24 h of dissolved oxygen (DO) recovery. Under hypoxic stress (DO: 1.2 ± 0.1 mg/L), the energy supply mode of fish changed from aerobic metabolism to anaerobic metabolism, and the serum glucose content and lactate dehydrogenase activity were significantly upregulated. Total protein, hepatic glycogen, and two key regulatory enzymes (i.e., hexokinase and pyruvate kinase) were differentially expressed in the liver, and mRNA expression of three genes (i.e., LDHA, GLUT1, and MCT2) also showed a high expression trend. In serum, three immune-related enzymes (i.e., alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase) were found to be involved in regulation by hypoxia and showed different levels of changing patterns. Expression of inflammatory genes (i.e., IL-8, IFNγ, MyD88, and NF-kB) were significantly regulated in liver. With prolongation of hypoxic stress, high expression of apoptotic genes (i.e., p53, Bax, Bcl-2, and Caspase-9) was closely related to the degree of apoptosis in the liver. Our investigation of the changes in energy metabolism, immune response, and apoptosis of E. coioides under hypoxia and reoxygenation (DO, 6.0 ± 0.1 mg/L) provides a theoretical bases for healthy aquaculture and selection of varieties with tolerance to hypoxia.

中文翻译：

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缺氧和复氧对橙斑石斑鱼 （Epinephelus coioides） 能量代谢、免疫反应和细胞凋亡的影响


缺氧是一种不利的环境条件，会对鱼类产生多种负面影响。与自然环境中的 Epinephelus coioides 相比，高密度培养物更容易经历缺氧条件。为了评估缺氧对 E. coioides 的影响，我们检查了缺氧 48 小时和溶解氧 （DO） 恢复 24 小时后的相关酶活性和基因表达。在低氧胁迫 （DO： 1.2 ± 0.1 mg/L） 下，鱼类的能量供应模式由有氧代谢转变为厌氧代谢，血清葡萄糖含量和乳酸脱氢酶活性显著上调。总蛋白、肝糖原和两种关键调节酶 （己糖激酶和丙酮酸激酶） 在肝脏中差异表达，三个基因 （即 LDHA 、 GLUT1 和 MCT2） 的 mRNA 表达也呈高表达趋势。在血清中，发现三种免疫相关酶 （即丙氨酸氨基转移酶、天冬氨酸氨基转移酶和碱性磷酸酶） 参与缺氧调节，并表现出不同程度的变化模式。炎症基因 （即 IL-8 、 IFNγ 、 MyD88 和 NF-kB） 的表达在肝脏中受到显著调节。随着缺氧应激的延长，凋亡基因 （即 p53 、 Bax 、 Bcl-2 和 Caspase-9） 的高表达与肝脏细胞凋亡程度密切相关。我们对缺氧和复氧 （DO， 6.0 ± 0.1 mg/L） 下 E. coioides 能量代谢、免疫反应和细胞凋亡变化的研究为健康水产养殖和选择耐缺氧品种提供了理论基础。