Huang Ming, Gao Qinfeng, Yang Xiaogang, Jiang Wenxin, Hao Lin, Yu Yining, Tian Yuan
Key Laboratory of Mariculture, Ministry of Education, Ocean University of China, No. 5 Yushan Road, Qingdao, 266003, Shandong Province, China.
Shandong Marine Group LTD., Jinan, Shandong, China.
Fish Physiol Biochem. 2023 Oct;49(5):1031-1042. doi: 10.1007/s10695-023-01244-y. Epub 2023 Oct 2.
Free amino acids (FAAs) are believed to play important roles in osmoregulation and buffer capacity in some aquatic animals, such as fishes. However, the potential roles of FAAs have not been systematically summarized and characterized until now. In the present study, the meta-analysis was conducted to investigate the relationships between FAAs and environmental salinities. Twenty published documents were included, accounting for 106 study cases. The effect sizes of total free amino acids (TFAAs), total essential amino acids (TEAAs), and total non-essential amino acids (TNEAAs) to salinity increase were calculated and determined by the restricted maximum likelihood (REML) method. It clearly showed that the elevated salinities significantly induced the contents of TFAAs, TEAAs, and TNEAAs at the ratio of 36%, 27%, and 29%, respectively. Faced to the salinity changes, the contents of FAAs in fishes under freshwater and seawater varied significantly, while the individuals under brackish water displayed relatively constant contents of FAAs. When salinity elevated, the contents of 17 amino acids in muscles significantly increased, suggesting the important roles of FAA metabolism in osmoregulation in fishes. The results also indicated that the effect sizes of TFAAs were positively related to the rates of salinity increases, and exhibited a significant quadratic linear relationship with temperatures. Additionally, the contents of FAAs also showed positive correlation with osmotic pressure, concentrations of plasma Na, Cl, and urea, implying their potential roles of FAAs in osmoregulation in fishes. These findings suggested that elevated salinities greatly induced the contents of FAAs in fishes, making a great contribution to maintaining the homeostasis of fishes in response to environmental salinity changes.
游离氨基酸（FAA）被认为在一些水生动物（如鱼类）的渗透调节和缓冲能力中发挥重要作用。然而，到目前为止，FAA的潜在作用尚未得到系统总结和表征。在本研究中，进行了荟萃分析以研究FAA与环境盐度之间的关系。纳入了20篇已发表的文献，共计106个研究案例。通过限制最大似然法（REML）计算并确定了总游离氨基酸（TFAA）、总必需氨基酸（TEAA）和总非必需氨基酸（TNAA）对盐度升高的效应大小。结果清楚地表明，盐度升高分别以36%、27%和29%的比例显著诱导了TFAA、TEAA和TNAA的含量。面对盐度变化，淡水和海水环境下鱼类体内FAA的含量差异显著，而半咸水环境下的个体FAA含量相对稳定。当盐度升高时，肌肉中17种氨基酸的含量显著增加，表明FAA代谢在鱼类渗透调节中发挥重要作用。结果还表明，TFAA的效应大小与盐度升高速率呈正相关，与温度呈显著的二次线性关系。此外，FAA的含量还与渗透压、血浆Na、Cl和尿素浓度呈正相关，这意味着FAA在鱼类渗透调节中具有潜在作用。这些发现表明，盐度升高极大地诱导了鱼类体内FAA的含量，为鱼类应对环境盐度变化维持体内平衡做出了重要贡献。
