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Simple Summary: Salinity has great influences on ion homeostasis and the physiological activities of crustaceans in aquatic environment. Transcriptome analysis of Macrobrachium nipponense showed that differentially expressed genes were mainly related to ion homeostasis, glucose metabolism and lipid metabolism. In addition, the morphological structure of M. nipponense gill tissue under high salinity stress showed significant changes in gill filaments, gill cavities and mucosal structures. Our study showed that salinity stress activates the ion transport channel of M. nipponense and promotes the up-regulation of glucose metabolism, and that high salinity causes damage to the gill tissue structure of M. nipponense. Salinity is an important factor in the aquatic environment and affects the ion homeostasis and physiological activities of crustaceans. Macrobrachium nipponense is a shrimp that mainly lives in fresh and low-salt waters and plays a huge economic role in China's shrimp market. Currently, there are only a few studies on the effects of salinity on M. nipponense. Therefore, it is of particular importance to study the molecular responses of M. nipponense to salinity fluctuations. In this study, M. nipponense was set at salinities of 0, 8, 14 and 22‰ for 6 weeks. The gills from the control (0‰) and isotonic groups (14‰) were used for RNA extraction and transcriptome analysis. In total, 593 differentially expressed genes (DEGs) were identified, of which 282 were up-regulated and 311 were down-regulated. The most abundant gill transcripts responding to different salinity levels based on GO classification were organelle membrane (cellular component), creatine transmembrane transporter activity (molecular function) and creatine transmembrane transport (biological function). KEGG analysis showed that the most enriched and significantly affected pathways included AMPK signaling, lysosome and cytochrome P450. In addition, 15 DEGs were selected for qRT-PCR verification, which were mainly related to ion homeostasis, glucose metabolism and lipid metabolism. The results showed that the expression patterns of these genes were similar to the high-throughput data. Compared with the control group, high salinity caused obvious injury to gill tissue, mainly manifested as contraction and relaxation of gill filament, cavity vacuolation and severe epithelial disintegration. Glucose-metabolism-related enzyme activities (e.g., pyruvate kinase, hexokinase, 6-phosphate fructose kinase) and related-gene expression (e.g., hexokinase, pyruvate kinase, 6-phosphate fructose kinase) in the gills were significantly higher at a salinity of 14‰. This study showed that salinity stress activated ion transport channels and promoted an up-regulated level of glucose metabolism. High salinity levels caused damage to the gill tissue of M. nipponense. Overall, these results improved our understanding of the salt tolerance mechanism of M. nipponense. [ABSTRACT FROM AUTHOR]

Salinity is an important factor in the aquatic environment and affects the ion homeostasis and physiological activities of crustaceans. Macrobrachium nipponense is a shrimp that mainly lives in fresh and low-salt waters and plays a huge economic role in China’s shrimp market. Currently, there are only a few studies on the effects of salinity on M. nipponense. Therefore, it is of particular importance to study the molecular responses of M. nipponense to salinity fluctuations. In this study, M. nipponense was set at salinities of 0, 8, 14 and 22‰ for 6 weeks. The gills from the control (0‰) and isotonic groups (14‰) were used for RNA extraction and transcriptome analysis. In total, 593 differentially expressed genes (DEGs) were identified, of which 282 were up-regulated and 311 were down-regulated. The most abundant gill transcripts responding to different salinity levels based on GO classification were organelle membrane (cellular component), creatine transmembrane transporter activity (molecular function) and creatine transmembrane transport (biological function). KEGG analysis showed that the most enriched and significantly affected pathways included AMPK signaling, lysosome and cytochrome P450. In addition, 15 DEGs were selected for qRT-PCR verification, which were mainly related to ion homeostasis, glucose metabolism and lipid metabolism. The results showed that the expression patterns of these genes were similar to the high-throughput data. Compared with the control group, high salinity caused obvious injury to gill tissue, mainly manifested as contraction and relaxation of gill filament, cavity vacuolation and severe epithelial disintegration. Glucose-metabolism-related enzyme activities (e.g., pyruvate kinase, hexokinase, 6-phosphate fructose kinase) and related-gene expression (e.g., hexokinase, pyruvate kinase, 6-phosphate fructose kinase) in the gills were significantly higher at a salinity of 14‰. This study showed that salinity stress activated ion transport channels and promoted an up-regulated level of glucose metabolism. High salinity levels caused damage to the gill tissue of M. nipponense. Overall, these results improved our understanding of the salt tolerance mechanism of M. nipponense.

Abstract In the present study, an acute toxic test was performed to assess the oxidative stress and genotoxic effects of the herbicide on the freshwater shrimp Macrobrachium nipponensis. The results showed that the 48-h and 96-h LC 50 values of Roundup to M. nipponensis were 57.684 mg/L and 11.237 mg/L, respectively. For further investigation, the shrimps were exposed to sublethal concentrations of 0.35, 0.70, 1.40, 2.80 and 5.60 mg/L for 96 h. A significant decrease in total haemocytes count (THC) was observed at concentration of 5.60 mg/L throughout the experiment. The level of superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) in all the treatments decreased in a dose- and time-dependent manner except for the concentration group of 0.35 mg/L. The malondialdehyde (MDA), hydrogen peroxide (H 2 O 2) and protein carbonyl in serum increased significantly at concentrations of 2.80 mg/L and 5.60 mg/L. A significant decrease in acetylcholinesterase (AChE) activity was observed at each concentration (P ＜0.05). In addition, the micronucleus (MN) frequency of haemocytes significantly increased (P ＜0.05) at concentrations of 1.40, 2.80 and 5.60 mg/L, whereas the comet ratio and %DNA in the tails exhibited a clear time- and dose-dependent response during the exposure. The analysis of the integrated biomarker response (IBR) showed the induction of oxidative stress biomarkers and the inhibition of antioxidants, and this dose-dependent relation suggests the sensitivity and availability of all the biomarkers. These results revealed that Roundup had a prominent toxic effect on M. nipponensis based on the antioxidative response inhibition and genotoxicity. Highlights • An acute toxic test was conducted to evaluate the effect of Roundup on oxidative stress and genotoxicity from Macrobrachium nipponensis. • Roundup could induce significant oxidative stress and genotoxic effect by sublethal concentration exposure. • All biomarkers except CAT were considered sensitive for toxicity assessment of Roundup exposure. [ABSTRACT FROM AUTHOR]

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The biotoxicity of heavy metals in water has always been the focus of ecological health research. In this study, the oxidative stress-associated toxicity of cadmium (Cd) and lead (Pb) at environmentally relevant concentrations on the hepatopancreas of Macrobrachium nipponensis was investigated based on multiple biomarker responses in a 28-day indoor exposure study. Changes in integrated biomarker responses (IBR) and their interactivity were subsequently analyzed. No dead individuals were found across any of the tested conditions. The chronic toxicity of heavy metals depended on their type and exposure time at the same concentration. At low concentrations, organisms have a regulatory capacity to cope with the excess reactive oxygen species (ROS) induced by Pb stress over time. In detail, the activity of superoxide dismutase (SOD) was inhibited by Pb stress at a high concentration as time passed. The sensitivity of metallothionein (MT) to Cd was stronger than Pb, and the potential for Cd to cause lipid peroxidation damage was higher than Pb. At the same time, Pb had a greater disturbance effect on the nervous system than Cd, especially in the early exposure stage. The contribution of Cd and Pb to the interaction effect varied dynamically with time and concentration of exposure, but mostly showed antagonism. The results of this study have important significance for guiding the diagnosis of ecological water health, the amendment of water quality criteria, and the management of wastewater discharge.

Trophic patterns of omnivorous freshwater shrimps, Exopalaemon modestus and Macrobrachium nipponensis, were investigated in two shallow eutrophic lakes by using stable isotope analysis. δ15N and δ13C of M. nipponensis and E. modestus increased with increasing body weight, which might be attributed to larger individuals ingesting organisms that feed higher up the food chain and/or increased assimilation of benthic food items with enriched isotopic signatures. Of the freshwater shrimps occurring in the studied lakes, those from Lake Taihu had significantly elevated δ15N and δ13C values (4.3‰ and 1.8‰, respectively) compared with those from the less eutrophic Lake Chaohu, indicating that the isotopic signature might partially reflect the trophic states of their habitats. Mixing model results suggested that the benthic food web provides the primary carbon source for both shrimp species, and that E. modestus assimilated relatively more pelagic food sources than M. nipponensis in these lakes. [ABSTRACT FROM AUTHOR]