Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510220, PR China.
Key Laboratory of South China Sea Fishery Resources Exploitation & Utilization, Ministry of Agriculture and Rural Affairs, South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, 510220, PR China; Shenzhen Base of South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shenzhen, 518000, PR China.
Aquat Toxicol. 2021 Jul;236:105841. doi: 10.1016/j.aquatox.2021.105841. Epub 2021 Apr 21.
Estuarine environmental have been reported to undergo significant fluctuations in oxygen concentrations with hypoxic conditions and subsequent re-oxygenation events being of significant concern for resident fish populations. In this study we assessed the toxicological effects of hypoxia and re-oxygenation on the liver of hypoxia-sensitive spotted sea bass (Lateolabrax maculatus) that were exposed to hypoxia (1.17 mg/L dissolved oxygen) for 12 h and then re-oxygenated for 12 h. The activities of glutamic-pyruvic transaminase and glutamic-oxalacetic transaminase in serum significantly increased under hypoxia (p < 0.05) and continued to increase during re-oxygenation (p < 0.05), indicating that normal liver function might be disrupted by hypoxia and might become worse during re-oxygenation for 12h. Total protein, albumin, and globulin levels in serum decreased under hypoxia but began to return to normal during re-oxygenation, showing that protein synthesis in the liver decreased during hypoxia but could be restored by re-oxygenation. We also used RNA-Seq technology to identify changes in gene expression in the liver during hypoxia and re-oxygenation. Transcriptome sequencing revealed that the hypoxia-inducible factor (HIF-1) signaling pathway, apoptosis, and purine metabolism transcripts were significantly enriched under hypoxia and re-oxygenation conditions. A total of 15 and 16 apoptosis-related genes were induced by hypoxia and re-oxygenation stress, respectively. The apoptosis index increased from the normal to the hypoxic condition and was highest under re-oxygenation. Additionally, 19 and 29 genes, that are involved in purine metabolism in the liver of L. maculatus during hypoxia and re-oxygenation, respectively, were dysregulated. Unexpectedly, the serum uric acid level significantly increased during hypoxia and significantly decreased under re-oxygenation, indicating the presence of purine metabolic disorder in the liver of L. maculatus. These results illustrate that hypoxia poses a pronounced threat to hepatocyte function in L. maculatus and that liver damage is difficult to reverse with 12 h of re-oxygenation, and it may actually become worse when re-oxygenation is established.
河口环境中的氧气浓度会发生显著波动，缺氧条件和随后的再氧合事件对当地鱼类种群构成重大关切。在这项研究中，我们评估了低氧和再氧合对易缺氧斑点鲈鱼（Lateolabrax maculatus）肝脏的毒理学影响，这些鱼在低氧（溶解氧 1.17 毫克/升）中暴露 12 小时，然后再氧合 12 小时。血清中谷氨酸-丙酮酸转氨酶和谷氨酸-草酰乙酸转氨酶的活性在低氧下显著升高（p<0.05），并在再氧合过程中持续升高（p<0.05），表明正常肝功能可能被低氧破坏，在 12 小时的再氧合过程中可能会恶化。血清中的总蛋白、白蛋白和球蛋白水平在低氧下降低，但在再氧合过程中开始恢复正常，表明肝脏中的蛋白质合成在低氧下减少，但可以通过再氧合恢复。我们还使用 RNA-Seq 技术来鉴定肝脏在低氧和再氧合过程中基因表达的变化。转录组测序显示，低氧诱导因子（HIF-1）信号通路、细胞凋亡和嘌呤代谢转录物在低氧和再氧合条件下显著富集。在低氧和再氧合应激下，分别有 15 个和 16 个与细胞凋亡相关的基因被诱导。细胞凋亡指数从正常条件到低氧条件增加，在再氧合条件下最高。此外，在低氧和再氧合期间，分别有 19 个和 29 个与鲈鱼肝脏嘌呤代谢相关的基因失调。出乎意料的是，血清尿酸水平在低氧时显著升高，在再氧合时显著降低，表明鲈鱼肝脏嘌呤代谢紊乱。这些结果表明，低氧对斑点鲈鱼肝细胞功能构成显著威胁，12 小时的再氧合难以逆转肝损伤，实际上再氧合建立后可能会恶化。
