Presence of a low molecular weight lectin in the coelomic fluid of the sea urchin Paracentrotus lividus

A low molecular weight (MW) lectin (Paracentrotus lividus small lectin, PlSL) has been found in the sea urchin, Paracentrotus lividus. After gel electrophoresis under denaturing conditions, PlSL exhibits a MW of 13 kDa, while its hemagglutinating activity is Ca2+-independent and inhibited by D-Glucose, L-Rhamnose, D-Arabinose, L-Fucose and N-Acetyl-D-glucosamine. Electrophoretic analysis of the coleomic fluid of P. lividus reveals that the presence of PlSL increases following immune challenge with bacteria, whereas it is annulled as a consequence of osmotic stress. Interestingly, two other putative inducible hemagglutinins of an approximate MW of 11 and 32 kDa were retrieved in concomitance with the stress-promoted disappearance of PlSL.