Salinity is a fundamental environmental factor in aquaculture, and arginine kinase (AK) plays imperative roles in innate immune feedback and stress resistance in invertebrates. In the current study, we cloned a full-length cDNA of arginine kinase 2 (MnAK2, GenBank number, MN149533) in Macrobrachium nipponense and analyzed its function through a salinity challenge using bioinformatic approaches. MnAK2 was expressed at the highest levels in hepatopancreas and muscle. Changes in the expression levels of MnAK2, enzymes involved in innate immunity, antioxidant enzymes, and antioxidant enzyme-related genes, and the glutathione and malondialdehyde contents were investigated after 6-week salinity treatment. The expression of MnAK2 gradually increased as salinity increased, and western blotting showed that MnAK2 was significantly upregulated in the 14 and 22 ppt salinity-treatment groups relative to the control group. The findings indicate that high salinity produces oxidative stress and that salinity below isotonic salinity might improve the antioxidant response in M. nipponense. MnAK2 may play a crucial role in the response to salinity stress in M. nipponense.

盐度是水产养殖中的基本环境因素，精氨酸激酶 (AK) 在无脊椎动物的先天免疫反馈和抗逆性中起着至关重要的作用。在目前的研究中，我们在日本沼虾中克隆了精氨酸激酶 2 的全长 cDNA（MnAK2，GenBank 编号，MN149533）并使用生物信息学方法通过盐度挑战分析其功能。MnAK2 在肝胰腺和肌肉中的表达水平最高。研究了 6 周盐度处理后 MnAK2、参与先天免疫的酶、抗氧化酶和抗氧化酶相关基因以及谷胱甘肽和丙二醛含量的表达水平的变化。MnAK2 的表达随着盐度的增加而逐渐增加，蛋白质印迹显示 MnAK2 在 14 和 22 ppt 盐度处理组中相对于对照组显着上调。研究结果表明，高盐度会产生氧化应激，而低于等渗盐度的盐度可能会改善日本M. nipponense的抗氧化反应. MnAK2 可能在M. nipponense对盐分胁迫的反应中起关键作用。