Immunocompetence Of Hemolymph And Hemocyanin In Scylla Serrata

Scylla serrata is one of the most valuable and economic breeds of crabs in Chinese southeast coastal area. With the rapid development of livestock breeding industry, great economical losses caused by infectious diseases have appeared in this aquaculture. An understanding of the ability in its immune defense will be helpful to the control of infectious diseases of this crab.In the current study, 1-DE proteomics technology was applied for characterization of diffferential protein expression in hemolymph, hepatocirrhosis, muscle of Scylla serrata infected by Vibrio parahaemolyticus, and hemocyanin, cryptocyanin and several other immune related proteins were identified.Furhtermore, hemagglutinating, agglutinating, anti-bacteria activity of hemocyanin and hemolymph were determined. Our results showed that when Scylla serrata was infected by Vibrio parahaemolyticus , there was a distinctly differential protein (named as SP) in hemolymph, which was identified as cryptocyanin. Besides it, ion transport-like peptide, actin, and bacteria responsive protein 2 in Scylla serrata's muscle and hepatocirrhosis were identified as altered proteins.Based on the analysis of Scylla serrata's hemolymph and hepatocirrhosis samples by 1-DE and 1-D immunoblotting with rabbit anti-hemocyanin serum, hemocyanin with 75 kDa was determined in response to bacterial infection, showing that it went down at first and then recovered to the normal level. This indicated that hemocyanin was an important immune factor in Scylla serrata and its concentration variety reflected in part its anti-disease activity.To study further hemocyanin'immunocompetence, agglutinating and anti-bacterium experiments in vitro were performed. We interestingly found that hemocyanin and hemolymph of Scylla serrata could be bound to bacteria and erythrocytes. Furhtermore, the agglutination with E. coli was determined by six outer membrane proteins of Escherichia coli K12, FadL, YbjP, OmpG, Tsx, OmpF, and NlpB.Results from anti-bacterium experiment indicated that bacterial growth was inhibited directly, but this inhibition was dependent on different solutions of purified hemocyanin by chromatograph. This could be explained by the variety of hemocyanin's components and also reflected its close relation with Scylla serrata's immune prevention ability.This study provides evidence on the anti-diseases activity of hemocyanin in Scylla serrata and will help us understand the immune status of hemocyanin in shellfish such as shrimps and crabs and develop the knowledge of shellfish's immune system and immune prevention.