SULFATED POLYSACCHARIDES FROM THE EGG JELLY LAYER ARE SPECIES-SPECIFIC INDUCERS OF ACROSOMAL REACTION IN SPERMS OF SEA-URCHINS

We have characterized the fine structure of sulfated polysaccharides f rom the egg jelly layer of three species of sea urchins and tested the ability of these purified polysaccharides to induce the acrosome reac tion in spermatozoa. The sea urchin Echinometra lucunter contains a ho mopolymer of 2-sulfated, 3-linked alpha-L-galactan. The species Arbaci a lixula and Lytechinus variegatus contain linear sulfated alpha-L-fuc ans with regular tetrasaccharide repeating units. Each of these sulfat ed polysaccharides induces the acrosome reaction in conspecific but no t in heterospecific spermatozoa. These results demonstrate that specie s specificity of fertilization in sea urchins depends in part on the f ine structure of egg jelly sulfated polysaccharide.