Effect Of Dietary Vitamin E On Reproduction And Expression Of Reproduction Related Genes Of Macrobrachium Nipponense

Macrobrachium nipponense also known as river prawn,which belongs to Palaemonidae,is one of the most important freshwater aquaculture species in Southeast Asia.But in recent years,with the size of shrimp farming expanding,oriental river shrimp has exposed degradation phenomenon of germplasm resources,which leads to decrease of production performance of product shrimp and hinders the development of freshwater shrimp farming industry.Although,there are few nutrition researches on reproductive performance of freshwater shrimp and it also has not been found about the mechanism of reproductive performance degradation.In this study,we used Macrobrachium nipponenseas research objects and tried to understand the mechanism of dietary vitamin E on Macrobrachium nipponense reproductive performance based on nutrition,physiology,biochemistry,histology,electron microscope and molecular biology methods,which provided valuable references about Macrobrachium nipponense reproductive performance researches.1.Effect of dietary vitamin E on growth and reproductive performance inMacrobrachium nipponense female shrimpVitamin E plays an important role in promoting reproduction of aquatic creatures.We selected average weight(0.358±0.033)g female shrimps to do a 10-week feeding trial and set six diets with 0,40,80,160,320,640 mg/kg vitamin E levels to explore the influence on reproductive performance of female shrimps.The results showed that 80 mg/kg group had the highest weight gain rates,spawning rates and lowest feed conversion rates,while there were no significant differences in survival rates and hepatosomatic index.The highest activities of lysozyme,acid phosphatase,and alkaline phosphatase in hepatopancreas were obtained in the 160 mg/kg group.The activities of superoxide dismutase,catalase,and glutathione peroxidase showed a decreasing trend in the hepatopancreas.The lowest content of malondialdehyde was obtained from 80 to 160 mg/kg vitamin E diets.Histological results showed that the number of restzellen cells,transport vesicles and lipid droplets increased in hepatopancreas and ovaries in suitable vitamin E diets.However,excessive vitamin E levels would damageto organization structure.The highest vitellognin and vitellognin receptor gene expressions were observed in 160 mg/kg vitamin E diets.Our results suggest that the appropriate supplement of vitamin E(80-160mg/kg)diets has a positive impact on the reproduction of Macrobrachium nipponense female shrimps.2.Effect of dietary vitamin E on growth and reproductive performance inMacrobrachium nipponense male shrimpWe selected average weight(0.252±0.031)g male shrimps to do a 10-week feeding trial and selected rest of shrimps to do injection of aeromonas hydrophila toxicity test.Compared with female feeding trial,the experimental results showed thatmale shrimp weight gain rates were significant higher than female shrimp growth speed.The male feeding trial results showed that survival rates and hepatosomatic indexs had no significant differences.When dietary vitamin E level was in 80mg/kg,it would significantly promote weight gain rates,feeding utilization and reproduction performance of freshwater shrimp.From antioxidant and non-specific immune enzyme activity detection,we could find that male shrimp enzyme activity was higher than female shrimp,and it had optimal range from 80 to 160mg/kg vitamin E diets.It was obvious that different dietary vitamin E level had significant influence on freshwater shrimp hepatopancreas composition of fatty acid.With dietary vitamin E level increased,linoleic acid(C18:2n-6,LOA)?DPA(C22:5n-3)and total polyunsaturated fatty acids(?PUFAs)showed a downward trend,while contents of EPA(C20:5n-3)?DHA(C22:6n-3)and total saturated fatty acid(?SFAs)experienced an upward trend.Besides,the contents of linolenic acid(18:3n-3,LNA)and monounsaturated fatty acids(?MUFAs)had no significant differences.From aeromonas hydrophila toxicity test,the lowest cumulative mortality was observed in 40-160mg/kg vitamin diets.It could be observed from ultrastructure observation that appropriate dietary vitamin E level would make hepatopancreas and testis of male shrimp structural integrity and enhance immunity.But high levels of vitamin E would have a negative impact on cell structure.3.Molecular cloning,characterization and expression of MnCDK2 and effect ofvitamin E on its expression in Macrobrachium nipponenseThe CDK2 cDNA was isolated from the hepatopancreas of Macrobrachium nipponense using RACE-PCR methods.The full-length cDNA of MnCDK2 obtained from present study was 1303 bp in length wih an open reading frame of 918 bp,encoding a putative peptide of 305 amino acids.The tissue-specific expression pattern study indicated that the highest expression were observed in ovaries and testis,and then in hepatopancreas.After feeding by six levels of vitamin E diets,the highest mRNA expression of MnCDK2 was observed in 160mg/kg dietary vitamin E diets and significant higher than other groups.Our results showed that MnCDK2 played an important role in reproduction of Macrobrachium nipponense,and its gene expressions were also affected by dietary vitamin E levels.