The Effects Of PH On The Growth And Its Intervention With Nutritional Methods In Juvenile Chinese Mitten Crab Eriocheir Sinensis

In this study has shown the effects of growth performance,immune resistance,antioxidant capacity and metabolism of Eriocheir sinensis under chronic pH stress.With the traditional physiological and biochemical methods and transcriptome molecular analysis,the metabolic regulation mechanism of adaptation to environmental stress factors in juvenile crabs were explored.In addition,the efficient and reliable nutrition methods to relieve environmental stress response of juvenile crabs was explored.According to this study,the stress physiology data of E.sinensis was supplemented.Moreover,the mechanism for adaptation of aquatic animals to the environment and accumulates data on water quality regulation studies in the aquaculture industry were improved.It also provides valuable reference for the development of new functional feeds for aquaculture.1 Effects of chronic pH stress on growth performance and material metabolism of juvenile Eriocheir sinensis and transcriptome analysisThis study explored the nagative effects of E.sinensis juvenile crab?average weight 2.1±0.1g?under three pH conditions,and the adaptation mechanisms that may regulate environmental pH stress injuvenile crabs also explored.The three pH test groups including acidic pH stress group?pH 6.5?,alkaline pH stress group?pH 9.5?and control group?p H 8.0?were set,and the culture period was 8 weeks.The experimental results are as follows:Under acidic pH stress environment,the growth performance of juvenile crab was significantly inhibited compared with the control group.Oxygen consumption rate?OCR?of crabs was significantly higher than that of the control group under acidic pH stress.In addition,the ammonia excretion rate?AER?of juvenile crabs was significantly inhibited under acid-base stress.Moreover,the experimental results of the hepatopancreas transcriptome after 8 weeks of chronic pH stress were as follows:There were 775 significantly up-regulated genes and 870significantly down-regulated genes in the alkline pH group compared to the control group.There were 1344 significant up-regulated genes and 1115 significantly down-regulated genes in the acidic pH stress.The transcriptome differential gene pathway analysis showed that,under alkaline pH stress,the signaling pathways of sucrose uptake,gluconeogenesis and carbohydrates were significantly downregulated?p<0.01?.In addition,genes related to urea metabolism signaling pathway were significantly up-regulated?p<0.01?.Under acidic pH stress,the signaling pathways such as glycolysis,tricarboxylic acid cycle,and oxidative phosphorylation of juvenile crabs were significantly upregulated?p<0.01?.Results showed that:Chronic pH stress has a significant effect on the growth performance,material metabolism,and stress status of the juvenile crab E.sinensis.Acidic stress has a significant inhibitory effect on the growth of juvenile crabs.Under alkaline stress,juvenile crabs have a certain wide tolerance,but the emergency effect in vivo is significant.In addition,transcriptome data analysis showed that in adaptation to pH stress,juvenile crabs,the body or there is control of carbohydrate metabolism,and further control the way of urea metabolism,thereby changing the whole body's ammonia nitrogen concentration,in order to stabilize the body's acid-base balance.However,this conclusion still needs further research and verification.2 Effects of Dietary L-Glutamine on Growth,Antioxidant Capacity and Ammonia-Nitrogen Metabolism of Chinese Mitten Crab,Eriocheir sinensis,under Chronic pH StressIn this experiment,0.5%L-glutamine-containing feed and the control feed?without L-glutamine?were designed with glycine to balance the total protein contain in three pH environments?6.5,8.0 and 9.5 pH?.The experimental crabs each weighed 0.26±0.04g and the experimental feeds used a practical feed formulation?38%crude protein and 7%crude fat?for a period of eight weeks.Result are as follows:The addition of 0.5%L-Glutamine in feed significantly increased the growth performance of young crabs under acidic pH stress.In addition,the addition of L-glutamine to feed has a significant effect on the antioxidant properties of juvenile crabs.Under acidic pH stress environment,the content of glutathione?GSH?in the hepatopancreas of juvenile crabs increased significantly.Under alkaline pH stress environment,malondialdehyde?MDA?content in hepatopancreas of juvenile crabs increased significantly.In addition,the addition of additional L-glutamine to feed had a significant effect on haemolymph ammonia concentration and urea nitrogen concentration.In addition,the addition of additional L-glutamine to feed had a significant effect on the haemolymph ammonia concentration and urea nitrogen concentration.The experimental results showed that the addition of 0.5%L-glutamine to feed had a significant effect on the pH relief of juvenile crabs,E.sinensis.After 96 hours of short-term pH stress,the ammonia concentration of hemolymph and hepatopancreas urea nitrogen concentration in juvenile crabs were significantly changed in the group with additional 0.5%L-glutamine to feed.Also,conbined with transcriptome data analysis have shown that under environmental pH stress,the juvenile crab of the Chinese mitten crab?E.sinensis?regulates the balance of ammonia?NH₃?and ammonium?NH₄⁺?concentrations in the body through the glutamine metabolic pathway to stabilize the acid-base balance of the organism.And adapt to changes in the pH of the environment.3 Effects of Dietary Vitamin C and E Supplementation on pH Stress of Chinese Mitten Crab?Eriocheir sinensis?In this study,four feed treatment groups were designed in three pH environments?6.5,8.0,and 9.5 pH?:control feed group?50 mg kg-1 Vc,50 mg kg-1 Ve?,and additional vitamin C feed?500 mg kg-1 Vc?,50 mg kg-1Ve),additional vitamin E feed?50 mg kg-1 Vc,300 mg kg-1 Ve?and co-administration of vitamins C and E feed?250 mg kg-1 Vc,150 mg kg-1 Ve?.The experiment was designed 3×4experiments with the average weight of juvenile crabs was 2.19±0.81g,and the culture period was 8 weeks.The results as follows:Vitamin C and E in feed can effectively relieve the pH stress of juvenile crabs,E.sinensis.Addition of vitamin C alone has little effect on pH stress relief.Adding additional vitamin E alone can significantly increase the activity of superoxide dismutase?SOD?,acid phosphatase?ACP?and alkaline phosphatase?AKP??p<0.05?,but the addition of vitamin E alone had a significant inhibitory effect on the growth performance of juvenile crabs.The combination of vitamins C and E had a significant effect on relieved the effects of pH stress of juvenile crabs.The growth performance of juvenile crabs such as weight gain rate and whole body crude protein content increased significantly.In addition,the combination of vitamins C and E significantly affects the crab's immune resistance.Under alkaline p H stress,the total blood cell counts?THC?of juvenile crabs increased significantly.Under acidic pH stress,the acid phosphatase?ACP?of juvenile crab was significantly increased.And under the acid-base stress environment,the anti-oxidation ability of juvenile crab has a certain increase trend?p>0.05?.The results showed that under the condition of chronic pH stress,the combination of vitamin C and E?250mg kg-1Vc,150 mg kg-1Ve?could significantly relieve the growth performance,immunity resistance and antioxidant capacity of the crabs,E.sinensis.Separate addition of vitamin E alone has a certain mitigation effect on oxidative stress in juvenile crabs,but its growth performance has a significant inhibitory effect.In addition,the effect of adding vitamins C and E in feed was poor compared to the effect of adding L-glutamine to feeds in response to pH stress.