Serological characterization of humoral lectins from the freshwater prawn Macrobrachium rosenbergii

We have detected and partially characterized multiple lectins present in the serum of the freshwater prawn Macrobrachium rosenbergii. Since agglutination of erythrocytes (RBC) is not abolished by treatment with Vibrio cholerae neuraminidase (VCN), Macrobrachium shows an agglutination pattern different from that of other sialic acid-specific lectins such as Limulus polyphemus lectin. However, after absorption with primate and bird VCN-treated RBC, Macrobrachium serum exhibits high titers with untreated and pronase-treated RBC and no agglutination of VCN-treated RBC, suggesting a typical sialic acid specific lectin agglutination profile. Hemagglutination-inhibition tests indicate that sialic acid containing compounds are the best inhibitors for Macrobrachium lectins. Subterminal sugars and type of linkage are probably important for the lectin binding since bovine submaxillary mucin (containing mainly terminal NANA-alpha-2 6-GalNAc-) is a better inhibitor than fetuin (containing mainly terminal NANA-alpha-2 leads to 3-Gal-) and colominic acid (-NANA-alpha-2 leads to 8-NANA-) is a weak inhibitor.