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Abstract：
Macrobrachium nipponense is an important commercial freshwater species in China. However, the ability of alkali tolerance of M. nipponense is insufficient to culture in the major saline-alkali water source in China. Thus, it is urgently needed to perform the genetic improvement of alkali tolerance in this species. In the present study, we aimed to analyse the effects of alkali treatment on gills in this species after 96 h alkalinity exposure under the alkali concentrations of 0 mmol/L, 4 mmol/L, 8 mmol/L, and 12 mmol/L through performing the histological observations, measurement of antioxidant enzymes, metabolic profiling analysis, and transcriptome profiling analysis. The results of the present study revealed that alkali treatment stimulated the contents of malondialdehyde, glutathione, glutathione peroxidase in gills, indicating these antioxidant enzymes plays essential roles in the protection of body from the damage, caused by the alkali treatment. In addition, high concentration of alkali treatment (> 8 mmol/L) resulted in the damage of gill membrane and haemolymph vessel, affecting the normal respiratory function of gill. Metabolic profiling analysis revealed that Metabolic pathways, Biosynthesis of secondary metabolites, Biosynthesis of plant secondary metabolites, Microbial metabolism in diverse environments, Biosynthesis of amino acids were identified as the main enriched metabolic pathways of differentially expressed metabolites, which are consistent with the previous publications, treated by the various environmental factors. Transcriptome profiling analyses revealed that the alkali concentration of 12 mmol/L has more regulatory effects on the changes of gene expression than the other alkali concentrations. KEGG analysis revealed that Phagosome, Lysosome, Glycolysis/Gluconeogenesis, Purine Metabolism, Amino sugar and nucleotide sugar metabolism, and Endocytosis were identified as the main enriched metabolic pathways in the present study, predicting these metabolic pathways may be involved in the adaption of alkali treatment in M. nipponense. Phagosome, Lysosome, Purine Metabolism, and Endocytosis are immune-related metabolic pathways, while Glycolysis/Gluconeogenesis, and Amino sugar and nucleotide sugar metabolism are energy metabolism-related metabolic pathways. Quantitative PCR analyses of differentially expressed genes (DEGs) verified the accuracy of the RNA-Seq. Alkali treatment significantly stimulated the expressions of DEGs from the metabolic pathways of Phagosome and Lysosome, suggesting Phagosome and Lysosome play essential roles in the regulation of alkali tolerance in this species, as well as the genes from these metabolic pathways. The present study identified the effects of alkali treatment on gills, providing valuable evidences for the genetic improvement of alkali tolerance in M. nipponense.
摘要：
日本沼虾是中国重要的商业淡水物种。然而,在中国主要的盐碱水源中培养，日本M.nipponense的耐碱能力不足。因此，迫切需要在该物种中进行耐碱性的遗传改良。在本研究中,我们旨在分析在碱浓度为0mmol/L的情况下，碱处理在96h碱度暴露后对该物种的ill的影响，4mmol/L，8mmol/L,和12mmol/L通过进行组织学观察，抗氧化酶的测量，代谢谱分析，和转录组谱分析。本研究的结果表明，碱处理刺激了丙二醛的含量，谷胱甘肽,谷胱甘肽过氧化物酶，表明这些抗氧化酶在保护身体免受损害中起着至关重要的作用，碱处理引起的。此外,高浓度的碱处理(>8mmol/L)导致了g膜和血淋巴血管的损伤,影响了ill的正常呼吸功能。代谢谱分析表明，代谢途径，次级代谢产物的生物合成，植物次生代谢产物的生物合成,不同环境中的微生物代谢，氨基酸的生物合成被确定为差异表达代谢产物的主要富集代谢途径。这与以前的出版物一致，受各种环境因素的影响。转录组谱分析表明，12mmol/L的碱浓度比其他碱浓度对基因表达的变化具有更大的调节作用。KEGG分析显示吞噬体，溶酶体,糖酵解/糖异生，嘌呤代谢,氨基糖和核苷酸糖代谢，在本研究中，内吞被确定为主要的富集代谢途径，预测这些代谢途径可能与日本M.碱处理的适应有关。吞噬体,溶酶体,嘌呤代谢,和内吞作用是免疫相关的代谢途径，而糖酵解/糖异生，氨基糖和核苷酸糖代谢是能量代谢相关的代谢途径。差异表达基因（DEGs）的定量PCR分析验证了RNA-Seq的准确性。碱处理显著刺激吞噬体和溶酶体代谢途径中DEGs的表达,表明吞噬体和溶酶体在该物种的耐碱调节中起着至关重要的作用，以及这些代谢途径的基因。本研究确定了碱处理对ill的影响，为日本M.耐碱性的遗传改良提供了有价值的证据。
