| The oriental river prawn,scientific name Macrobrachium nipponense,has an important economic position in China’s aquaculture industry.The high temperature environment will affect the life activities of M.nipponense metabolism,feeding behavior and respiratory rate.Excessive reactive oxygen species substances are produced in the body of M.nipponense to cause oxidative stress and damage the immune system,and even cause stopping eating and death.High temperature will also affect the quality of aquaculture water environment,cause the dissolved oxygen concentration to drop sharply,exacerbate the death of M.nipponense due to hypoxia,and cause serious impact on the M.nipponense breeding industry.Therefore,exploring the response mechanism to high temperature is of great significance to the healthy development of M.nipponense aquaculture industry.This study explored the effects of high temperature on the tissue structure of the hepatopancreas and gill,the changes in antioxidant enzyme activity,and the response of heat shock protein genes of M.nipponense.Analyzed the effects of high temperature stress on M.nipponense from the tissue levels,physiological and biochemical,provide a theoretical basis for the healthy cultivation of M.nipponense.1.The effects of high temperature stress on the structure of the hepatopancreas and gill tissue of M.nipponenseThe volume of secretory cells and transport vesicles increased significantly when hepatopancreatic tissue of M.nipponense was under high temperature stress for 12 h and 24 h,while the storage cells did not change significantly,and they were still distributed in dots.When the stress was 36 h and 48 h,the basement membrane boundary was fused.During the high temperature stress,the storage cells in the hepatopancreas tissue did not change significantly.The gill filaments deformed,the lamellar epithelium was bent,disordered arrangement of columnar epithelial cells and the blood cell arrangement was disordered when gill tissue of M.nipponense was under heat stress for 12 h.When the stress was24 h,the arrangement of blood cells was disordered and the number increased,and the epithelial cells had obvious hyperemia.At 36 h of stress,the gill filaments were severely deformed,and the blood cells were messy.After 48 h of stress,the gill filament structure was bent,and there were still blood cell disorder and hyperemia.2.The effect of high temperature stress on antioxidant capacity of M.nipponense.The activity of superoxide dismutase(SOD)in the hepatopancreas tissue of prawns was obviously higher than that in the control group at 12 h and 36 h of high temperature stress(P<0.05).The activity of glutathione transferase(GST)was obviously higher than that of the control group at all time points during high temperature stress(P<0.05).The activity of glutathione peroxidase(GPX)increased slightly at 24 h,which was not significantly different from the control group(P>0.05),and was obviously lower than the control group at 48 h(P<0.05).Catalase(CAT)activity was obviously higher than the control group at 36 h(P<0.05).In the gill,the SOD activity showed a downward trend after high temperature stress for 12 h,and was significantly lower than that of the control group at 24 h,36 h and 48 h(P<0.05).Compared with the control group,GST activity was obviously higher at24 h and 36 h under high temperature stress(P<0.05),and it fell back at 48 h,which was not obviously different from the control group(P>0.05).CAT activity increased first and then decreased during high temperature stress,and the activity was higher than that of the control group.In the hepatopancreas,the content of malondialdehyde(MDA)within 0-24 h was obviously lower than that of the control group.At 36 h,its content was obviously higher than that of the control group,and then decreased with the stress time(P<0.05).In the gill,the MDA content was obviously higher than that of the control group at 12 h and24 h,and then decreased with the time of high temperature stress(P<0.05).3.The effect of high temperature stress on the heat shock proteins of M.nipponense.The HSP21 and HSP70 cognate 3(HSC70-3)genes were cloned in full length using RACE technology.The c DNA sequence of the Mn HSP21 gene is 3,465 bp long.Mn HSP21 gene has a conserved α-crystallin domain(ACD)that is unique to small heat shock proteins.Mn HSP21 was clustered with Macrobrachium rosenbergii HSP21.The c DNA sequence of Mn HSC70-3 gene is 2,175 bp in length.Mn HSC70-3 gene contains three HSP70 family tag sequences.Mn HSC70-3 was clustered with Eriocheir sinensis HSC70-3.The gene expression patterns of heat shock protein in the hepatopancreas and gill tissues of M.nipponense under heat stress were detected by q PCR.The results showed that the expressions of four heat shock protein genes in hepatopancreas and gill tissues were induced to increase under high temperature stress,and the increasing trends of gene expression in the hepatopancreas tissues was more obvious than that in the gill tissues.Mn HSP21 significantly increased in the hepatopancreas under high temperature stress at 12 h(P<0.05),reached the maximum value at 36 h of stress of all experimental time points,and decreased to the control group level at 48 h of stress(P>0.05).In the gill tissues,Mn HSP21 gene increased significantly at 12 h(P<0.05),but decreased at24 h.The expression of Mn HSP60 in the hepatopancreas tissue showed a continuous upward trend(P<0.05),and decreased to the control group level at 48 h in gill tissue(P>0.05).The expression of Mn HSC70-3 in the hepatopancreas and gill tissues was significantly higher than that in the control group(P<0.05).The expression of Mn HSP90 in the hepatopancreas kept increasing,and in the gill tissue,it showed increasedat 36 h. |
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