A putative role for carbohydrates in sea urchin gastrulation

Many studies have examined the effects of lectins on embryonic development. Recently, it has been shown that lectins actually enter the blastocoel of sea urchin embryos without microinjection and bind to specific cell types. The present study was performed to examine the effects of lectins on sea ur chin gastrulation. Strongylocentrotus purpuratus sea urchin embryos were in cubated with several lectins at concentrations from 0.01 mu g/ml to 100 mu g/ml at 15-28 h in the presence or absence of the preferential binding suga rs. The most interesting findings were that the mannose specific lectins Le ns culinaris agglutinin (LcH) which binds to secondary mesenchyme cells inv olved in archenteron anchoring and Pisum sativum (PSA) caused exogastrulati on. Wheat germ agglutinin (WGA) which binds to primary mesenchyme cells inv olved in skeletogenesis caused defective skeletogenesis. Our findings sugge st that D-mannose-like residues (LcH and PSA specific sugar) may function i n archenteron development and anchoring, while N-acetyl-D-glucosamine-like groups (WGA specific sugar) may contribute to control of primary mesenchyme positioning and function. Specific carbohydrate-containing receptors may, therefore, be of importance in specific gastrulation events.