Antimicrobial Function Research Of Fatty Acid Binding Protein In Chinese Mitten Crab(Eriocheir Sinensis)

Chinese Mitten Crab is a special species in aquaculture,and it has formed a unique crab culture,brought a remarkable social and economic benefits.From the aquaculture perspective,Chinese Mitten Crab has trembling disease and Triops disease.From the basic research perspective,the immune mechanism of crabs and other crustaceans research is still inadequate.therefore,the study of eriocheir sinensis immune response mechanism will not only make us a better understanding of crustaceans immune defense system,but also can have a profound impact on disease control and prevention.Like other invertebrates,eriocheir sinensis only rely on innate immune to detection and process the danger signal when exposed to pathogenic microorganism,while the Toll and IMD signaling pathways are the key signal transduction pathways known in invertebrates.Our preliminary study found fatty acid binding protein(FABP)can be combined with bacteria,restrain the growth of the bacteria,but whether it can deal with the invasion of germs by intracellular signaling pathways is still unclear.The antibacterial function of the EsFABP has been confirmed at present,however,their genetic structure information is still incomplete up to now,and also the spatiotemporal expression when responsed to pathogen invasion.In this study,the gene structure of two FABP isoforms in Chinese mitten crab were uncovered,and they were compared with another published EsFABP10(Gong,Li et al.2010).The result revealed that all the FABPs have four exons,which were separated by introns with various lengths.The mRNA expression profile of EsFABP3,EsFABP9,and ESFABP10 post Vibrio parahemolyticus(V.parahemolyticus)and Staphylococcus aureus(S.aureus)stimulation were analyzed,and it revealed that,all of EsFABPs in hemocytes could be induced with bacteria injection.The result has been confirmed again in the cultured hemocytes with bacteria in vitro.In Eriocheir sinensis,as an important immune effect factor,AMPs were secreted by hemocytes,and it can inhibit and kill pathogens directly.In order to have a further understanding of FABPs antibacterial function,in this study,we used RNAi to verify whether FABPs can affect the expression of AMPs.EsFABP3 was knockdown successfully in cultured hemocytes with or without bacteria stimulation.Moreover,the bacterial CFU in the cell culture medium of EsFABP3 knocked down hemocyte were significant increased,while the expression of AMPs decreased significantly,which predicted the potential regulation of EsFABP3.Furthermore,the translocation of Esdorsal were inhibited in hemocyte where EsFABP3 were knockdown.All in all,all these results suggest that FABP may participate in Toll signaling in Chinese mitten crab.This study further completed the structure information of Chinese mitten crab FABPs,and also the immune function of FABPs.It will provides a new way for FABP immune research of crustaceans,and also provides references for the immune mechanism of invertebrates FABP.