CARBOHYDRATES OF THE ORGANIC SHELL MATRIX AND THE SHELL-FORMING TISSUE OF THE SNAIL BIOMPHALARIA-GLABRATA (SAY)

Sulfated carbohydrates may play a role in the biomineralization of the molluscan shell. The carbohydrates of the extracted water-insoluble o rganic shell matrix (LM) of the freshwater snail Biomphalaria glabrata were identified as glucose, mannose, galactose, and N-acetyl-glucosam ine, whereas the water-soluble organic matrix (SM) additionally contai ned N-acetyl-galactosamine. A specific lectin binding pattern of the m atrix was obtained. One prominent protein of the SM, with a size of 19 .6 kDa and a pI of 7.4, was shown to be a glycoprotein with terminal g lucosyl or mannosyl moieties. The acidic constitutents of the matrix s howed a variety of possible terminal sugars, indicating a heterogenous mixture of proteoglycans or glycosaminoglycans (GAGs) and glycoprotei ns. At the shell-forming mantle edge, an alcian-blue-positive material was observed in the periostracum groove (PG), the belt, and apically in the cells of the outer mantle epithelium (OME). With the help of le ctins, all sugars in question were detected in the PG and the belt, wh ereas the OME was bound by glucose/mannose- and GlcNac-specific lectin s only. Although the complete set of GAGs will be produced in the PG a nd the belt, a very acidic fraction of GAGs and the 19.6-kDa protein c an also be delivered by the OME.