Concanavalin A-Binding Glycoconjugates In The Freshwater Sponge, Ephydatia mulleri

Abstract

This preliminary study investigated the distribution and role of cell surface carbohydrates which were suspected to affect proximal cell interactions such as recognition and adhesion. Recognition and adhesion play roles in the development of many organisms but are easily followed in freshwater sponges. The distribution of glycoconjugates in a freshwater sponge Ephydatia mulleri was investigated with the Periodic acid-Schiff (PAS) reaction and lectin histochemistry. PAS revealed the distribution of general carbohydrate in the sponge. Lectin histochemistry used Concanavalin A (ConA), a mannosebinding lectin, coupled through avidin and biotin to horseradish peroxidase enzyme (HRP) to reveal the location of mannose-containing glycoconjugates. PAS disclosed an abundance of carbohydrates in the extracellular matrix. Localization of ConA-binding glycoconjugates revealed their presence in the extracellular matrix, inside the cells, and on cell surface. The role of these glycoconjugates in sponge development from gemmules was assessed by ConA blockage of cell surface glycoproteins. Blocking the cell surface recognition glycoproteins with Concanavalin A showed no clear cut effect on cell adhesion and sponge fusion.