To gain knowledge on the immune response in Scylla paramamosain under low salinity challenge, S. paramamosain we investigated digital gene expression (DEG) in S. paramamosain hemocytes using the deep-sequencing platform Illumina Hiseq XTen. A total of 97,257 high quality unigenes with mean length 786.59 bp were found to be regulated by low salinity challenge, among which 93 unigenes were significantly up regulated, and 71 were significantly down regulated. Functional categorization and pathways analysis of differentially expressed genes revealed that immune signaling pathway including cAMP and cGMP signaling pathway were affected in low salinity stress. Cellular immunity-related genes including low-density lipoprotein receptor-related protein 6 (LRP6) and xanthine dehydrogenase (XDH) were down-regulated, indicating phagocytosis and oxygen dependent mechanism of phagocyte were suppressed in low salinity stress; Humoral immunity-related genes serine proteases and serpins 3 were up- and down-regulated, respectively, suggest that the proPO system was influenced by low salinity significantly; Moreover, processes related to immune response including carbohydrate metabolism, protein synthesis and lipid transport were found differentially regulated, implying the integrity of the immune response in low salinity stress. This study gained comprehensive insights on the immune mechanism of S. paramamosain at low salinity stress at the molecular level. The findings provide a theoretical basis for understanding immune mechanisms of S. paramamosain under low salinity stress, and technical reference for evaluating physiological adaptation in fresh water environment.

为了了解低盐度挑战下Sylla paramamosain中的免疫反应，S。paramamosain我们在研究数字基因表达（DEG）S. paramamosain血细胞使用深度测序平台Illumina Hiseq XTen。低盐度挑战共调控97257个平均长度786.59 bp的高质量单基因，其中93个单基因显着上调，71个显着下调。差异表达基因的功能分类和信号通路分析表明，在低盐度胁迫下，包括cAMP和cGMP信号通路在内的免疫信号通路受到影响。低密度脂蛋白受体相关蛋白6（LRP6）和黄嘌呤脱氢酶（XDH）等细胞免疫相关基因被下调，表明在低盐度胁迫下吞噬作用和吞噬细胞的氧依赖性机制受到抑制；体液免疫相关基因丝氨酸蛋白酶和丝氨酸蛋白酶抑制剂3分别上调和下调，提示proPO系统受到低盐度的显着影响；此外，发现与免疫反应有关的过程（包括碳水化合物代谢，蛋白质合成和脂质转运）被不同地调节，这暗示着在低盐度胁迫下免疫反应的完整性。这项研究获得了有关免疫机制的全面见解。S. paramamosain在分子水平上的低盐度胁迫下。这些发现为理解低盐胁迫下副链霉菌的免疫机制提供了理论基础，为评估淡水环境下的生理适应性提供了技术参考。