| There are a wide range of saline-alkali waters in the world,but due to the complex water composition in saline-alkali waters,many freshwater economic aquaculture varieties cannot survive,which greatly restricts the development and utilization of saline-alkali waters.The exposure of aquatic animals to high carbonate alkalinity will cause oxidative stress,which greatly affects the normal survival and reproduction of aquatic animals.In this study,we researched the stress mechanism of carbonate on Eriocheir sinensis,which provided a theoretical basis for the continuous development of Salt alkali water culture.In this experiment,Eriocheir sinensis were divided into five carbonate treatment groups,0 mmol/L,4.375 mmol/L,8.75 mmol/L,17.5mmol/L,35 mmol/L groups,three replicates for each group and 30 crabs each replicate,Hepatic-pancreatic tissues of Eriocheir sinensis were sampled at 24 h,48 h and 96 h.This study investigated the effects of carbonate stress on oxidative damage,microstructure,MAPK pathway,mTOR and autophagy related gene expression in the hepatopancreas of Eriocheir sinensis.The test results are shown as follows:1.Transmission electron microscopy in hepatopancreas of Eriocheir sinensis showed that,the control cell membrane was intact,the mitochondria and ER were abundant in the cytoplasm,the mitochondrial structure was clear,and the intercellular tight junctions were clearly visible.However,in the alkali stress group,the cell membrane was severely deformed,less mitochondria and mitochondria showed ridge breaks,more heterochromatin in the nucleus,more autolysosomes and autophagic vesicles.2.The results of the oxidative stress index enzyme showed that,when compared with the control group,at 24 h and 48 h,the activities of antioxidant enzymes SOD,GSH,GSH-Px and T-AOC all increased first and then decreased,MDA showed a trend of decreasing first and then increasing,and the CAT activity decreased with increasing concentration,which was significantly lower than that of the control group(P<0.05).At 96 h,the activities of SOD,GSH-Px,T-AOC,and CAT decreased with increasing base concentration and were significantly lower than those in the control group(P<0.05),however,the activities of GSH and MDA increased with increasing concentration and were significantly higher than the control groups(P<0.05).3.The MAPK pathway gene expression results are shown that the gene expression of MAPK and P38 was significantly increased at 24 h,48 h,and 96 h(P<0.05),With a gradual increase with concentration.However,JNK expression was significantly higher than control expression at 48 and 96 h and showed a trend to increase with increasing concentration at 96 h(P<0.05).4.The results of the mTOR gene expression levels showed that,the mTOR gene expression level were significantly lower at 24 h,48 h and 96 h compared with the control group(P<0.05).At24 h,there were no significant differences among the other carbonate stress groups except for the low expression in the 35 mmol/L group(P>0.05).The expression results were similar at 48 h and96 h,with no significant differences between the carbonate stress groups except for the 8.75mmol/L group(P>0.05).5.The results of the autophagy-related genes expression levels showed that,compared with the control group,the expression of autophagy-related genes(ATG5,ATG12,ATG7,and GABARAP)was significantly increased at 24 h,48 h,and 96 h(P<0.05),and it increased gradually with the increase of carbonate concentration.In conclusion,the above results showed that induced the activation of the P38/MAPK pathway and inhibited the expression of mTOR through oxidative stress when subjected to carbonate stress,thus causing autophagy in the hepatopancreas of Eriocheir sinensis.The research conducted in this experiment will improve the ecological environment of saline-alkali areas,and effectively use the resources of barren waters,so as to provide impetus for the sustainable development of China’s fishery. |
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