Ficolin在毛蚶抗弧菌感染中的作用OA北大核心CSTPCD

The FBG-domain constituting proteins(ficolins)play significant roles in immune defense in animals.In invertebrates,ficolins act as pattern recognition receptors and immune effectors in immune defense.In this study,a ficolin gene(designed as SsFic1)was cloned from the ark shell Scapharca subcrenata.The coding sequence of SsFic1 was 897 bp,encoding a peptide of 298 amino acids containing a typical FBG domain and coiled domain but lacking a collagen-like domain.SsFic1 mRNA was widely distributed in all tested tissues,with high relative ex-pression levels in the hepatopancreas and gills.The transcripts of SsFic1 were not detected in fertilized eggs or four-cell embryos,suggesting that it is not a maternal immune gene.SsFic1 expression could be induced at high levels by Vibrio parahaemolyticus,LPS,and Glu.Knockdown of SsFic1 by RNAi significantly inhibited the ex-pression of PAF,C1qDC,complement C3,SsFic3,and the enzyme activities of CAT,SOD,and PO,while the ex-pression of TEP,C1q2,and SsFic2 was upregulated.In addition,knocking down SsFic1 reduced the total number and phagocytosis rate of hemocytes when ark shells were challenged by V.parahaemolyticus,resulting in a lower survival rate and higher cell apoptotic levels in ark shells.In summary,SsFic1 may play crucial roles in immune defense against pathogen infection in ark shells by regulating the complement and proPO activating pathways,which is conducive to the immunology of shellfish and the breeding of disease-resistant strains.