Jiang Yuhan, Qi Ming, Zhang Jinpeng, Wen Yuanlin, Sun Jiamin, Liu Qigen
Centre for Research on Environmental Ecology and Fish Nutrition of the Ministry of Agriculture, Shanghai Ocean University, Shanghai, China.
Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China.
Front Physiol. 2022 May 20;13:853850. doi: 10.3389/fphys.2022.853850. eCollection 2022.
The Qingtian paddy field carp () is a local carp cultivated in the rice field of Qingtian county, Zhejiang province, China. The paddy field environment is distinct from the pond environment. Due to the inability to artificially increase oxygen, the dissolved oxygen greatly changes during the day. Therefore, investigating the physiological regulation to the changes of acute dissolved oxygen in Qingtian paddy field carp (PF-carp) will dramatically clarify how it adapts to the paddy breeding environment. The high tolerance of Qingtian paddy field carp to hypoxia makes it an ideal organism for studying molecular regulatory mechanisms during hypoxia process and reoxygenation following hypoxia in fish. In this study, we compared the changes of metabolites in the hepatopancreas during hypoxia stress and the following reoxygenation through comparative metabolomics. The results showed 131 differentially expressed metabolites between the hypoxic groups and control groups. Among them, 95 were up-regulated, and 36 were down-regulated. KEGG Pathway enrichment analysis showed that these differential metabolites were mainly involved in regulating lipid, protein, and purine metabolism PF-carps could require energy during hypoxia by enhancing the gluconeogenesis pathway with core glutamic acid and glutamine metabolism. A total of 63 differentially expressed metabolites were screened by a comparison between the reoxygenated groups and the hypoxic groups. Specifically, 15 were up-regulated, and 48 were down-regulated. The KEGG Pathway enrichment analysis supported that PF-carp could continue to gain energy by consuming glutamic acid and the glutamine accumulated during hypoxia and simultaneously weaken the ammonia-transferring effect of amino acids and the toxicity of ammonia. By consuming glycerophospholipids and maintaining the Prostaglandin E content, cell damage was improved, sphingosinol synthesis was reduced, and apoptosis was inhibited. Additionally, it could enhance the salvage synthesis and synthesis of purine, reduce purine accumulation, promote the synthesis of nucleotide and energy carriers, and assist in recovering physiological metabolism. Overall, results explained the physiological regulation mechanism of PF-carp adapting to the acute changes of dissolved oxygen at the metabolic level and also provided novel evidence for physiological regulation of other fish in an environment with acute changes in dissolved oxygen levels.
青田稻田鲤（）是中国浙江省青田县稻田养殖的本地鲤鱼品种。稻田环境与池塘环境不同。由于无法人工增氧，稻田中溶解氧在白天变化很大。因此，研究青田稻田鲤（PF-鲤）对急性溶解氧变化的生理调节机制，将极大地阐明其如何适应稻田养殖环境。青田稻田鲤对缺氧的高耐受性使其成为研究鱼类缺氧过程及缺氧后复氧期间分子调节机制的理想生物。在本研究中，我们通过比较代谢组学方法，比较了缺氧应激及随后复氧过程中青田稻田鲤肝胰腺中代谢物的变化。结果显示，缺氧组与对照组之间有131种差异表达代谢物。其中，95种上调，36种下调。KEGG通路富集分析表明，这些差异代谢物主要参与脂质、蛋白质和嘌呤代谢的调节。PF-鲤在缺氧期间可能通过增强以谷氨酸和谷氨酰胺代谢为核心的糖异生途径来获取能量。通过比较复氧组和缺氧组，共筛选出63种差异表达代谢物。具体而言，15种上调，48种下调。KEGG通路富集分析表明，PF-鲤可以通过消耗缺氧期间积累的谷氨酸和谷氨酰胺继续获取能量，同时减弱氨基酸的氨转运作用和氨的毒性。通过消耗甘油磷脂并维持前列腺素E含量，改善细胞损伤，减少鞘氨醇合成，抑制细胞凋亡。此外，它还可以增强嘌呤的补救合成和合成，减少嘌呤积累，促进核苷酸和能量载体的合成，并协助恢复生理代谢。总体而言，研究结果在代谢水平上解释了PF-鲤适应溶解氧急性变化的生理调节机制，也为其他鱼类在溶解氧水平急性变化环境中的生理调节提供了新证据。
