A novel approach for investigating glycan involvement in embryonic cellular interactions. II. lectin studies

Abstract

Here we investigate the effects of 5 lectins at concentrations ranging from 0.0005 mg lectin ‐ 0.5 mg lectin per ml low calcium sea water on specific cellular interactions in the NIH model sea urchin embryo Lytechinus pictus using a microplate assay. 3 separate experiments were conducted with 12 microwells in each experiment at each lectin concentration, yielding a total of 36 wells with hundreds of embryos assessed for each lectin concentration. Lectins(or no lectin controls) were added at 24 hrs of development and the effects on archenteron/elongation/binding to the blastocoel roof were recorded after an additional 24 hrs. Phytolacca americana (specific for N‐acetyl‐beta‐D‐glucosamine residues) inhibited archenteron elongation/attachment to the blastocoel roof in a concentration dependent manner when controls and treated embryos were compared (p less than 0.0001 comparing complete archenterons in controls versus experimentals). Pisum sativum (specific for alpha‐D‐glucose and alpha‐D‐mannose) and Ulex europaeus UEA 1 (specific for L‐fucose) lectins both caused exogastrulation, where not only does the archenteron not attach but it everts from the embryo proper (p value of less than 0.0001 comparing exogastrulation in controls versus experimentals). Helix pomata (specific for N‐acetyl‐alpha‐D‐galactosamine) and Glycine max (specific for N‐acetyl‐alpha‐D‐galactosamine and D‐galactose) had no effects on the embryos, like the controls.The results indicate that specific lectins that bind to specific saccharides influence a model cellular interaction. Most important, however, is that the microplate approach used here is able to quantitatively assess specific probed events in living embryos (Supported by NIH NIGMS SCORE (S0648680), RISE, MARC , the Joseph Drown Foundation and the Sidney Stern Memorial Trust).