Growth And Development Of Juvenile Schizothorax Grahami And Its Acute Toxicity To Five Pesticides

In this study,Schizothorax grahami juvenile fish were used as experimental materials.on the one hand,the growth law,digestive enzyme activity and PepT1 gene expression of Schizothorax grahami juvenile fish were investigated by means of developmental biology,enzymology and molecular biology,on the other hand,the growth law,digestive enzyme activity and DNA gene expression of Schizothorax grahami fish juvenile were investigated.The acute toxic effect of pesticide on juvenile Schizothorax grahami split belly fish was discussed.on this basis,the chronic toxicity caused by dimethoate and the effect of vitamin C on it were studied.the main results were as follows:1.In order to understand the growth characteristics of juvenile Schizothorax grahami fish.The body length and weight of Schizothorax grahami fish larvae,juveniles and juveniles were measured,and the overall development trend was made.the growth characteristics of Schizothorax grahami fish larvae aged 168?210 days were studied emphatically.five growth models were used to simulate the growth process of body length and weight.The optimum growth equation was obtained by comparative analysis,and its growth characteristics were explored by fatness and growth index.The results showed that there was a power function relationship between body length and weight:W=0.013L^3.234?R²?0.970?,and the growth rate equation of body length was v_L=1.3092-0.1104t+0.0024t².The growth rate equation of body weight was v_W=8.8033-0.6592t+0.0126t².The results showed that the juvenile of Schizothorax grahami fish grew at an allometric rate,and the growth rate of body weight was faster than that of the body.2.The activity characteristics of digestive enzymes in juvenile Schizothorax grahami were studied.The results showed that:?1?the activity of LPS in different tissues was as follows:liver>intestine>muscle.the activity of LPS in intestine and liver was lower before 182 days of age,and increased significantly after 182 days of age.the activity of SOD in liver at 182 days of age was 5.7 times higher than that of intestinal tract.6.31 times as much as muscle;?2?the order of AMS activity in different tissues was intestinal tract>liver>muscle,which showed ascending trapezoidal changes in intestinal tract and muscle,but decreased after 210 days of age in liver;?3?the order of pepsin activity was intestinal tract>muscle>liver,which showed descending trapezoidal changes in intestinal tract and liver,while the activity of pepsin in muscle rose and floated wavy,and reached the maximum at 210 days of age,but it was still lower than that of intestinal tract.Higher than the liver.The results showed that:?1?the LPS activity of Schizothorax grahami fish changed in stages during the growth process,and?2?Schizothorax grahami fish secreted AMS and pepsin intermittently.3.The expression of PepT1 gene in juvenile Schizothorax grahami was studied.The results showed that the expression of PepT1 gene increased from 168 to 175 days of age,decreased gradually from 175 days to 203 days of age,and the expression of PepT1 gene increased significantly at 210 days of age compared with 203 days of age?P<0.05?.The results showed that the expression of PepT1 gene was regulated by nutrient demand and protein content.4.The acute toxic effects of glyphosate ammonium salt,glyphosate,dimethoate,fenpropathrin and abamectin on juvenile fish of Schizothorax grahami fish were studied and the safety of glyphosate ammonium salt,glyphosate,dimethoate,fenpropathrin and abamectin were evaluated.The results showed that the LC₅₀0 of glyphosate ammonium salt,glyphosate,dimethoate,fenpropathrin and abamectin were 5.755 mg/L,210.7 mg/L,39.598 mg/L,0.009 mg/L and 0.0122 mg/L,respectively.The safe concentrations were 1.223 mg/L,62.66 mg/L,10.182 mg/L,0.0018 mg/L,0.0031 mg/L.The results showed that the order of sensitivity of the five pesticides was fenpropathrin>abamectin>glyphosate ammonium salt>dimethoate>glyphosate.5.The toxic effect of dimethoate on juvenile Schizothorax grahami and the effect of Vc on it were studied.The results showed that:?1?the activities of EROD,CAT,MDA and AchE were significantly increased in the experimental group larger than SC,while the activities of EROD,CAT,MDA and AchE were lower in the SC group and the less than SC group,?2?after adding Vc,the activities of EROD,CAT,MDA and AchE were lower.The activity of EROD increased,while the activities of CAT,MDA and AchE decreased in different tissues.The results showed that:?1?when the damage was greater than SC,the damage to the body could not be repaired to a certain extent,but had no effect on the body when it was less than SC,?2?Vc could scavenge free radicals in organisms to a certain extent and enhance drug resistance,It has played an active role in protecting the body from oxidative damage caused by exogenous substances.6.The effect of dimethoate on HSP70 mRNA of juvenile Schizothorax grahami fish and the effect of Vc on it were studied.The results showed that the expression of HSP70 mRNA was significantly induced by different concentrations of dimethoate?P<0.05?.With the prolongation of stress time,the highest concentration group was excluded from 24 h to 96 h.There was no significant change in the other groups?P>0.05?.After 120 h of Vc addition,the expression level of HSP70 gene in each group decreased significantly?P<0.05?,and the expression level in the lower two concentration groups was close to that in the control group.The results showed that dimethoate could induce the expression of HSP70 gene in juvenile Schizothorax grahami fish,Vc could significantly reduce the expression of dimethoate gene,enhance the tolerance of juvenile Schizothorax grahami fish to dimethoate,and help the body to complete its self-regulatory function.