| In the process of fish breeding in saline alkali water,when the seedlings cultivated in fresh water are fed in separate ponds,if they are directly put into medium and high saline alkali water,the seedlings often can not adapt to the new environment,resulting in high mortality.However,after a certain adaptive domestication of medium and low salinity,it can effectively enhance the stress resistance of seedlings and improve the survival rate.The adult fish weight of Lucio Barbus capito can reach 5～10kg.The fish has excellent breeding characteristics such as wide feeding habits,fast growth speed,delicious meat and strong stress resistance.It was introduced into China from Uzbekistan in 2003.So far,relevant research has been carried out on artificial breeding technology,breeding biology,breeding technology and salt alkali tolerance of Lucio Barbus capito.However,the relevant research on the saline alkali domestication of Spinibarbus has not been reported.In this study,the single factor acclimation experiment of salinity（Na Cl）and alkalinity（Na HCO3）and salt alkali interaction acclimation experiment were set up.By exploring the histological level（structural changes of gill,liver and intestine tissues）of the Juvenile Lucio Barbus capito after 7 days of low concentration salt alkali acclimation and non acclimation Physiological and biochemical levels（white blood cells/WBC,lymphocytes/lymph,monocytes/mon,neutrophils/Gran,red blood cells/RBC,hemoglobin/HGB content,plasma urea/urea concentration,blood glucose/glu-g content,albumin ALB content,plasma osmotic pressure,aspartate aminotransferase/AST,alanine aminotransferase/ALT,acid phosphatase/ACP,alkaline phosphatase/AKP,lactate dehydrogenase/LDH in gill tissue,superoxide dismutase/SOD,total antioxidant enzyme/T-AOC,catalase/CAT,glutathione peroxidase/GSH-PX,malondialdehyde/MDA in liver tissue）,molecular levels（Hsp70 and Hsp90 gene expression in gill and liver tissues）and their differences in gut microbial diversity,compare the magnitude of changes in these indicators,peak size,peak occurrence time and recovery time,analyze the differences in changes in adaptive mechanisms between domesticated and undomesticated,further elucidate the response mechanisms of Juvenile Lucio Barbus capito to saline stress,and provide a theoretical basis for the culture technology of Juvenile Lucio Barbus capito in medium to high saline waters This study will provide a theoretical basis for the establishment of culture technology for Lucio Barbus capito in medium and high saline waters.1.Effects of salinity acclimation on physiological function and intestinal microbiome of of juvenile Luciobarbus capitoIn order to explore the physiological adaptation changes in tissue structure,immune stress and gut microbial diversity after salinity domestication,three groups were set up in this study.The salinity of 4g/L was acclimated for 7 days and then put into the water of8g/L salinity.The un-acclimated group was directly put into the water of 8g/L salinity.Changes in indicators related to differences in immune stress,tissue structure and gut microbial diversity in juveniles at 0h,6h,12h,24h,48h,96h,and 7d.The experimental results showed that:the molecular,physiological,biochemical and genetic indicators of the juveniles in the domesticated group and the non-domesticated group increased first and then decreased of phenomenon with the extension of the stress time in the water body with a salinity of 8g/L.In the early stage of stress,although the peak time of each index in the domesticated group and the non-acclimated group was the same,the physiological and biochemical indicators（WBC,Lymph,Gran,Mon,UREA,GLU-G,ALB,osmotic pressure）in the plasma of juvenile fish in the domesticated group,and transaminases（AST,ALT）,antioxidant enzymes（SOD,CAT,GSH-PX,MDA）and heat stress protein gene expression（Hsp70,Hsp90）in liver tissue,phosphatases（AKP,ACP）in gill tissue)and metabolic enzymes（LDH）and heat stress protein gene expression（Hsp70,Hsp90）,the increase amplitude and peak size were significantly smaller than those in the unaccustomed group（P<0.05）,indicating that the juveniles of the domesticated group experienced Under high salinity stress,it showed less stress response in terms of stress level.In addition,after 7 days of 8 g/L Na Cl salinity stress,both the acclimated group and the non-acclimated group were able to recover to the level of the control group,indicating that the juvenile carp has better self-regulation and recovery ability to the 8 g/L salinity environment However,the plasma osmotic pressure,plasma ALB content,and Hsp70 and Hsp90 gene expression in gill tissue of juveniles in the domesticated group all recovered to the level of the control group earlier than that in the non-acclimated group.There was no significant difference between the gut microbes of the acclimated group and the non-acclimated group and the control group,indicating that the 7-day low-salinity acclimation measure did not have a great impact on the composition of the intestinal flora.In terms of the magnitude of increase,peak magnitude and recovery time of the physiological function indices of juvenile Luciobarbus capito,when juvenile Luciobarbus capito were subjected to 8 g/L Na Cl salinity after salinity domestication,the physiological level reflected that the stress intensity of the organism was reduced and showed better self-regulation and recovery ability,and some of the physiological indices could recover to the initial level in a shorter period of time;salinity domestication did not have a significant effect on Salinity domestication did not have a significant effect on gut microbial diversity.2.Effects of alkalinity domestication on physiological function and intestinal microbiome of juvenile Luciobarbus capitoThe experiment of Na HCO3alkalinity adaptive acclimation was carried out on the juvenile Luciobarbus capito with a body mass of（13.66±1.26）g.the control group was cultured in fresh water all the time.The acclimated group was acclimated for 7 days with a alkalinity of 20 mmol/L and then put into a alkalinity water body of 40 mmol/L.the non acclimated group was directly put into a alkalinity water body of 40 mmol/L.The results were measured and compared at the 0h,6h,12h,24h,48h,96h and 7 day the changes of of blood physiological and biochemical indexes,immune antioxidant system,tissue structure and intestinal microbial diversity of juvenile fish after being put into 40 mmol/L alkaline water.The results showed that the gill filaments in the domesticated group and the non domesticated group contracted and became thinner,the gill flakes became thinner and extended outward,and the spacing increased.Blood osmotic pressure,immune cells（WBC,lymph,Gran,Mon）,hemoglobin（Hgb）,red blood cells（RBC）,platelets（PLT）,urea（urea）,albumin（ALB）,platelet hematocrit（PCT）,transaminase（AST,ALT）and other physiological and biochemical indexes of domesticated and non domesticated fish,as well as the expression of antioxidant enzymes in liver antioxidant system and heat stress protein genes in gills and liver tissue,In the process of alkalinity stress from 0h to7d,it showed the change trend of increasing first and then decreasing（P<0.05）,and the peak size and upward increase range of the domesticated group were significantly lower than those of the non domesticated group（P<0.05）,and the blank group did not show significant changes during this period（P>0.05）.The blood routine index parameters,SOD enzyme and cat enzyme in liver tissue and the peak expression of HSP70 and HSP90 genes in gill and liver tissue in domesticated group were later than those in non domesticated group.On the 7th day of high alkalinity stress,the urea concentration in blood,immune cells（lymph,Mon）,blood routine parameters,ALB content,transaminase activity,SOD,cat,GSH Px,MDA parameters and heat stress protein HSP70 and HSP90gene expression in domesticated group were significantly lower than those in non domesticated group（P<0.05）,but they were significantly higher than those in control group（P<0.05）.After a certain degree of alkalinity（20 mmol/L）domestication,juvenile Luciobarbus capito were subjected to a higher alkalinity（40 mmol/L）water stress within a 7-d stress time frame,reflecting a reduced intensity of stress on the physiological level,which could mitigate the damage caused by higher alkalinity stress;alkalinity domestication could significantly affect the intestinal microbial diversity of juvenile Luciobarbus capito.3.Effects of salinity acclimation on physiological function and intestinal microorganisms of juvenile Luciobarbus capito.The juvenile Luciobarbus capito with a body mass of（15.66±1.45）g was selected to carry out Na HCO3alkalinity adaptive domestication experiment.The white group was cultured in fresh water all the time.After 7 days of adaptive domestication with a alkalinity of 20 mmol/L and a salinity of 4 g/L,the domesticated group was put into a water body with a alkalinity of 20 mmol/L and a salinity of 8 g/L.the non domesticated group was directly put into a water body with a alkalinity of 20 mmol/L and a salinity of8 g/L.the alkalinity of 20 mmol/L was measured and compared Changes of blood physiological and biochemical indexes,immune antioxidant system,tissue structure and intestinal microbial diversity of juvenile fish at 0h,6h,12h,24h,48h,96h and 7d in water with salinity of 8 g/L.The results showed that the physiological and biochemical indexes such as blood osmotic pressure,blood routine parameters（RBC,HGB,PLT）,urea,leukocyte,albumin content and transaminase（AST,ALT）of domesticated and non domesticated fish,as well as the antioxidant indexes in liver tissue antioxidant system（T-AOC,cat,GSH-Px,MDA）,immune stress indexes in gill tissue（ACP,AKP,LDH）and the gene expression of heat stress proteins（HSP70,Hsp90）in gill and liver tissue,In the process of saline alkali stress from 0h to 7d,the change trend was first increased and then decreased（P<0.05）,but the peak value and increase range of domesticated group in the initial stage of stress were significantly higher than those of non domesticated group（P>0.05）;The contents of plasma TG and TC in domesticated group and non domesticated group decreased first and then increased,and the valley value and decline range of domesticated group were significantly smaller than those in non domesticated group.The indexes of the domestication group at 7d and 0h were significantly different from those of the control group,and the differences between the indexes at 7d and 0h were increased.After 7 d of domestication in water with an alkalinity of 20 mmol/L and a salinity of4 g/L,juvenile Luciobarbus capito were still in a strong state of stress when placed in a higher salinity water environment,reflecting that the intensity of stress to which the organism was subjected did not diminish. |
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