Saline-alkaline water aquaculture has become a key way to mitigate the reduction of freshwater aquaculture space and meet the increasing global demand for aquatic products. To enhance the comprehensive utilization capability of saline-alkaline water, it is necessary to understand the regulatory mechanisms of aquatic animals coping with saline-alkaline water. In this study, our objective was to elucidate the function of proline metabolism in the alkaline adaptation of Nile tilapia (Oreochromis niloticus). Expose Nile tilapia to alkaline water of different alkalinity for 2 weeks to observe changes in its growth performance and proline metabolism. Meanwhile, to further clarify the role of proline metabolism, RNA interference experiments were conducted to disrupt the normal operation of proline metabolic axis by knocking down pycr (pyrroline-5-carboxylate reductases), the final rate-limiting enzyme in proline synthesis. The results showed that both the synthesis and degradation of proline were enhanced under carbonate alkalinity stress, and the environmental alkalinity impaired the growth performance of tilapia, and the higher the alkalinity, the greater the impairment. Moreover, environmental alkalinity caused oxidative stress in tilapia, enhanced ion transport, ammonia metabolism, and altered the intensity and form of energy metabolism in tilapia. When the expression level of the pycr gene decreased, the proline metabolism could not operate normally, and the ion transport, antioxidant defense system, and energy metabolism were severely damaged, ultimately leading to liver damage and a decreased survival rate of tilapia under alkalinity stress. The results indicated that proline metabolism plays an important role in the alkaline adaptation of Nile tilapia and is a key regulatory process in various biochemical and physiological processes.

中文翻译：

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脯氨酸代谢对于尼罗罗非鱼 （Oreochromis niloticus） 的碱性适应至关重要


盐碱水养殖已成为缓解淡水养殖空间减少和满足全球对水产品日益增长的需求的关键途径。为了提高盐碱水的综合利用能力，有必要了解水生动物应对盐碱水的调控机制。在这项研究中，我们的目的是阐明脯氨酸代谢在尼罗罗非鱼 （Oreochromis niloticus） 碱性适应中的功能。将尼罗罗非鱼暴露于不同碱度的碱性水中 2 周，以观察其生长性能和脯氨酸代谢的变化。同时，为了进一步阐明脯氨酸代谢的作用，进行了 RNA 干扰实验，通过敲低脯氨酸合成中的最终限速酶 pycr （吡咯啉-5-羧酸还原酶） 来破坏脯氨酸代谢轴的正常运作。结果表明：碳酸盐岩碱度胁迫下脯氨酸的合成和降解均增强，环境碱度损害了罗非鱼的生长性能，碱度越高，损害越大。此外，环境碱度导致罗非鱼氧化应激，增强离子转运、氨代谢，并改变罗非鱼能量代谢的强度和形式。当 pycr 基因表达水平降低时，脯氨酸代谢不能正常运作，离子转运、抗氧化防御系统和能量代谢受到严重破坏，最终导致肝损伤，碱度胁迫下罗非鱼存活率下降。 结果表明，脯氨酸代谢在尼罗罗非鱼的碱性适应中起重要作用，是各种生化和生理过程中的关键调控过程。