Molecular Characterization Of Complement Component 3 In Mytilus Coruscus Under The Stress Of Lipopolysaccharide And Copper

The complement system is a major humoral system of innate immunity,playing an significant role in host defense against pathogen.Complement component 3 is a vital molecule in the complement system,whose functions focus on immune regulation,immune defense and immune pathology.Several invertebrates C3 genes have been characterized but few in mollusk.The thick shell mussel,Mytilus coruscus,which is widely distributedin Yellow Sea,Korean Peninsula,and Hokkaido waters of Japan,represents one of the most economically important mussel species in China.In recent years,this mussel is suffering from increasing sicknesses triggered by multiple environmental changes containing a wide range of biotic?bacterial and viral?and abiotic?heat or cold shock,hyperosmotic stress,food-deprivation,reduced oxygen level,heavy metal concentrations and organic or inorganic chemical substances?stresses,and resulted in a remarkable economic loss.Based on the current cultivation status of Mytilus coruscus,in this paper,the Complement Component C3 was cloned.At the same time,the expression of Complement Component C3 in the Mytilus coruscus under lipopolysaccharide and copper ion stress was analyzed so as to replenish the gaps of Complement Component C3 in the Mytilus coruscus.Meanwhile,these will provide pratical instruction for the improvement of aquaculture technology in the face of bacteria attacking and marine pollution.Specific research results are as follows:In this study,the complete cDNA of C3 gene was firstly isolated from the Mytilus coruscus using RACE technique.Following,functional domains,phylogenetic status,tissue distribution and expression profiles response to lipopolysaccharide and Cu2+challenge of Mc-C3 were analyzed.The deduced Mc-C3 protein possessed the characteristic structure features present in its homologs and contained the A2M_N2,ANATO,A2 M,A2M_comp,A2M_recep,and C345 C domains,as well as the C3 convertase cleavage site,thioester motif,and conserved Cys,His,and Glu residues.Mc-C3 was widely expressed in all seven healthy tissues whereas predominantly expressed in gill.After lipopolysaccharide and Cu2+ exposure,the expressions of corresponding transcripts were significantly up-regulated in the early stage and decreased to normal level as induction time went by.These results indicated that the C3 played the acute-phase effect in thick shell mussel during the challenge of outer stimuli,suggesting that this complement molecule might function as a pattern recognition molecule in innate immunity of mussels.Moreover,these results contributes to the breeding selection and production of Mytilus coruscus.