Study On Growth And Activities Of Related Enzymes Of Lanthanum And Selenium For Centropristis Striata

This study considerd Centropristis striata as research object,demonstrated the effects of rare earth aqueous La³⁺on the growth,liver,kidney,serum antioxidant enzymes,and Na⁺-K⁺-ATPase activity of juveniles of Centropristis striata.In addition,Se-Met was added to the feed,the effects of growth performance,tissue selenium content,serum and liver antioxidant enzyme activity,and serum biochemical indicators were researched.Based on the quadratic curve model and broken line model,the selenium content of diets was analyzed for the weight gain rate of fronds,selenium content of liver,and lysozyme activity.The suitable dietary selenomethionine contents of Centropristis striata was analyzed.The results of study are as follows:1.Juvenile Centropristis striata with body weight of?68.19±4.0?g were reared in a170 L plastic tank at rate of 15 individuals per tank and exposed to lanthanum?La??prepared from Lanthanum chloride at a dose of 0,0.1,2,5,10,20,and 30 mg.L^-11 at water temperature of 17-26?for 90-day exposure in order to study the long-term effects of different concentrations of aqueous La on growth and activities of superoxide dismutase?SOD?,catalase?CAT?and Na⁺-K⁺-ATPase and MDA content in liver,kidney and gill tissues of Centropristis striata.It was found that the juveniles had the best growth at the La³⁺concentration of 5 mg.L^-1,with the maximal weight gain rate of74.29%and specific growth rate of 0.61%.La³⁺led to significantly inhibit the activities of SOD and CAT?P<0.05 and P<0.01?in liver and kidney.Nevertheless,it has an insignificant influence on the activities of SOD and CAT in gill at a low La³⁺concentration(0-2 mg.L^-1),but inhibited their activity at a high concentration(20mg.L^-1and 30 mg.L^-1).There was significantly lower MDA content in liver in the juveniles exposed to La³⁺?P<0.01?,whereas there was increase in MDA content in kidney and gill first and then decline in the juveniles exposed to La³⁺,the similar case in the activity of Na⁺-K⁺-ATPase in liver,kidney and gill,that is,Na⁺-K⁺-ATPase was activated at low-concentration of La³⁺exposure.Under the effect of high La³⁺concentration,however,there were no significant changes in the activity of Na⁺-K⁺-ATPase in gill,but the activity of such enzyme in liver and kidney?P<0.05 and P<0.01?was inhibited significantly.2.A total of 540 juvenile Centropristis striata with the initial body weight of?81.62±0.75?g were randomly divided into 6 groups with 3 replicates per group and 30fish per replicate.The fish in those groups were fed 6 experimental diets containing0.09?control group?,0.21,0.44,0.58,0.77 and 1.05 mg/kg selenium for 8 weeks,respectively.Results showed as follows:the weight gain rate?WGR?increased firstly and decreased subsequently with dietary selenium content increasing,and the highest value appeared at the 0.58 mg/kg selenium group,which was significantly higher than that other groups?P<0.05?.The feed conversion rate?FCR?reached the lowest when the dietary selenium content was 0.58 mg/kg,which was significantly lower than that of the control group?P<0.05?.No significant differences were found in the muscle moisture and crude protein content?P>0.05?.The muscle crude lipid content was highest when dietary selenium content was 0.77 mg/kg,which was significantly higher than that in the control group?P<0.05?.Muscle ash content was highest when dietary selenium content was 0.58 mg/kg,which was significantly higher than other groups?P<0.05?.The dietary selenium content did not significantly affected the selenium content in the muscle and kidney?P>0.05?.The selenium content in liver and serum increased firstly and decreased subsequently with dietary selenium content increasing,and the 0.58 and0.77mg/kg selenium group had the highest value,which was significantly higher than that in other groups and control group,respectively?P<0.05?.The serum glutathione peroxidase?GSH-Px?activity was increased significantly with increasing dietary selenium content?P<0.05?.The liver GSH-Px activity was increased first and then decreased with increasing dietary selenium content,and it was highest when dietary selenium content was 0.58 mg/kg,which was significantly higher than that in the control group?P<0.05?.The liver superoxide dismutase?SOD?activity was firstly increased and then decreased with increasing dietary selenium content.The serum glutathione reductase?GR?,catalase?CAT?,liver glutathione S-transferase?GST?,and SOD activity were firstly increased and then decreased with dietary selenium content.The lowest value appeared at the highest level?1.05 mg/kg?.The immunoglobulin M?IgM?and activity of lysozyme in the serum were increased with the dietary selenium level increasing.The highest values were appeared when the selenium content was 0.77mg/kg,which were significantly higher the control group?P<0.05?.Based on WG,liver GPX activity and lysozyme activity by quadratic curve and broken-line model,the dietary Se requirement of juvenile Centropristis striata are 0.62,0.82 and 0.67 mg/kg,respectively.