| Salinity is one of the most important factors of environmental,which directly affects the immune function of crustaceans.In recent years,the study on immunity mechanism of crustaceans under salinity stress has been a hot research field internationally.However,the molecular mechanism for innate immune response of Scylla paramamosain was unclear.In particular,there is a lack of information about the immunoregulation mechanism of S.paramamosain hemocytes under salinity stress.In this study,we focused on the mud crab S.paramamosain,dominant breeding species in Hainan.By means of Digital Gene Expression Profiling(DGE)to gain the differentially expressed gene(DEG)and analysis the underlying molecular mechanism of immune response to low salinity stress.The validation experimental was performed with real-time quantitative PCR(RT-QPCR)to examine the DEG.The effects of low salinity on the regulations pathways of intracellular and immune parameter were investigated in S.paramamosain.This study includes the following aspects:1.Construction and analysis on expression profile of immune-associated genes in hemocytes of S.paramamosain under low salinity stress.To gain the knowledge in the immune response of the mud crab Scylla paramamosain to low salinity challenge,a deep-sequencing platform Illumina Hiseq XTen was used to identify the genes responding to the challenge of low salinity 10‰ for 24 h in S.paramamosain with crabs under salinity 30‰ as the control.A total of 97,257 high quality unigenes with mean length 786.59 bp were found to be regulated by low salinity challenge,which 93 unigenes were significantly up regulated,and 71 were significantly down regulated.Functional categorization and pathways of differentially expressed genes revealed that immune signaling pathway,cellular immunity,humoral immunity and immune related-processes were the differentially regulated aspects occurring during low salinity stress.This study gained insights on the immune mechanism of S.paramamosain at low salinity stress at the molecular level.2.Study on the immune signaling pathway of hemocytes in S.paramamosain under low salinity stress.The effects of low salinity on the intracellular regulations pathways were investigated in S.paramamosain.The results shows that AC/c AMP/PKA pathway factors of all the pathway factors were significantly up-regulated under low salinity stress.Among them,AC,c AMP and PKA reached the maximum at 12 h.Expected that the PLC decreased and reached the minimum at 24h;the c GMP and protein kinase C reached their maximum value at 12 h.This suggests that PKA/PKC is regulated by two pathways to respond adaptively to low salinity stress.However,the PKC signaling pathway may not be regulated step by step by the PLC/c GMP/PKC pathway,and there may be other pathway factors that affect the c GMP and act as protein kinase C.However,it is certain that the low salinity stress affects the intracellular signal transmission of the hemocytes and the immune response process of the crabs.3.Low salinity stress affected the immune defense function of S.paramamosain.In this study,the immune parameters in the low-salinity group were determined,including total hemocytes count(THC),prophenoloxidase(pro PO)in hemocytes,plasma phenoloxidase(PO),phagocytic activity,antimicrobial activity,bacteriolytic activity and agglutination activity.In our study,except for the significant increase of PO activity at 12 h under low salt stress,other immune parameters significantly decreased under low salt stress.The parameters of cellular immunity including THC and phagocytic activity reached the minimum at 12 h.The pro PO activity,antibacterial activity,lysozyme activity,agglutination activity related to humoral immunity all reached the lowest value at 12 h.With the exception of THC,all parameters returned to the control group level 48 h after the experiment.The results showed that the immune defense function of S.paramamosain was affected and inhibited under low salinity stress. |
PDF Full Text Request