Meng Xianliang, Jayasundara Nishad, Zhang Jingyan, Ren Xianyun, Gao Baoquan, Li Jian, Liu Ping
Key Laboratory of Aquatic Genomics, Ministry of Agriculture and Rural Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, People's Republic of China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, People's Republic of China.
Nicholas School of the Environment, Duke University, Durham, NC 27713, United States.
Ecotoxicol Environ Saf. 2021 Nov 25;228:113026. doi: 10.1016/j.ecoenv.2021.113026.
Ammonia is a common environmental pollutant in aquatic ecosystem and is also a significant concern in closed aquaculture systems. The threat of ammonia has been increasing with rising anthropogenic activities including intensified aquaculture. In this study, we aimed to investigate ammonia toxicity and metabolism mechanisms in the hepatopancreas, a major organ for Vitellogenin (Vtg) synthesis and defending against ammonia stress, of female swimming crab Portunus trituberculatus which is an important fishery and aquaculture species, by integrating physiological, transcriptome and metabolome analyses. The results revealed that ammonia exposure (10 mg/L, an environmentally relevant concentration) resulted in a remarkable reduction in vtg expression and depression of multiple signaling pathways for reproductive regulators including methyl farnesoate, ecdysone and neuroparsin, demonstrating for the first time that ammonia impairs swimming crab female reproduction. In addition, a number of important genes and metabolites in glycolysis, the Krebs cycle, fatty acid β-oxidation and synthesis were significantly downregulated, indicating that changes in ammonia levels lead to a general depression of energy metabolism in hepatopancreas. After ammonia exposure, an increased level of urea and a reduction of amino acid catabolism were observed in hepatopancreas, suggesting that urea cycle was utilized to biotransform ammonia, and amino acid catabolism was decreased to reduce endogenous ammonia generation. Furthermore, antioxidant systems were altered following ammonia exposure, which was accompanied by proteins and lipid oxidations, as well as cellular apoptosis. These results indicate that ammonia leads to metabolic suppression, oxidative stress and apoptosis in P. trituberculatus hepatopancreas. The findings improve the understanding for the mechanisms of ammonia toxicity and metabolism in P. trituberculatus, and provide valuable information for assessing potential ecological risk of environmental ammonia and improving aquaculture management.
氨是水生生态系统中常见的环境污染物，也是封闭水产养殖系统中的一个重大问题。随着包括集约化水产养殖在内的人为活动增加，氨的威胁一直在上升。在本研究中，我们旨在通过整合生理、转录组和代谢组分析，研究三疣梭子蟹（一种重要的渔业和水产养殖物种）雌蟹肝胰腺中氨的毒性和代谢机制，肝胰腺是卵黄蛋白原（Vtg）合成和抵御氨胁迫的主要器官。结果表明，氨暴露（10mg/L，一个与环境相关的浓度）导致vtg表达显著降低，以及包括法尼酸甲酯、蜕皮激素和神经肽在内的多种生殖调节因子信号通路受到抑制，首次证明氨会损害三疣梭子蟹雌蟹的繁殖能力。此外，糖酵解、三羧酸循环、脂肪酸β-氧化和合成中的一些重要基因和代谢物显著下调，表明氨水平的变化导致肝胰腺能量代谢普遍受到抑制。氨暴露后，肝胰腺中尿素水平升高，氨基酸分解代谢减少，表明利用尿素循环对氨进行生物转化，减少氨基酸分解代谢以减少内源性氨的产生。此外，氨暴露后抗氧化系统发生改变，同时伴有蛋白质和脂质氧化以及细胞凋亡。这些结果表明，氨会导致三疣梭子蟹肝胰腺发生代谢抑制、氧化应激和细胞凋亡。这些发现增进了对三疣梭子蟹氨毒性和代谢机制的理解，并为评估环境氨的潜在生态风险和改善水产养殖管理提供了有价值的信息。
