Purification And Characterization Of A New Form Of Vitellogenin From Amphioxus (Branchiostoma Belcheri Tsingtaunese) And Its Immune Function Study

An oocyte-yolk protein was purified by double-step chromatography from the ovaries of amphioxus Branchiostoma belcheri tsingtaunese. The purified protein appeared as a single band of approximately 500 kDa in native PAGE, which is larger than the amphioxus vitellogenin (Vg) reported previously, and was reduced to a single band of 150 kDa in SDS-PAGE. The protein was characterized as a phospholipoglycoprotein by native PAGE and staining of gels for carbohydrates with periodic acid/Schiff reagent, for lipid with Sudan black B and for phosphorus with methyl green. In addition, the protein could cross-react with mouse antiserum against amphioxus Vg. Thus, we conclude that the purified protein is a new form of vitellogenin, which consists of a homodimer of two identical subunit polypeptides plus lipid.In the hemagglutination assay, the purified Vg of amphioxus could agglutinate the chick, grass carp and toad erythrocytes with the hemagglutination(HA) titers of 210, 2s and 23 respectively. It was showed for the first time that the Vg of amphioxus had hemagglutinating activities. The hemagglutinating activities of Vg could be inhibited by D-Galactose and D-glucose in the experiment using chick erythrocyte. The D-glucose has the highest inhibitory activity with about 62.5 mmol/L of minimal inhibitory concentration against Vg.The antibacterial activities of Vg were analysed by using colony forming unit technique against Escherichia coli and Staphylococus aureu. Vg showed obvious antibacterial activity against Escherichia coli and the biggest growth inhibition rate couldreach 90%. Vg did not exhibite evidently growth inhibition against Staphylococus aureu. It is the first time reported that Vg has antibacterial activities.