Lectin-binding glycoproteins in the developing and adult snail CNS

Glycoproteins are complex molecules of the cell surface and the extracellular matrix (ECM) playing a fundamental role in the migration, guidance and synapse formation of neurons. In the present study, the glycosylated protein composition and localization were investigated in the adult and developing CNS of an aquatic (Lymnaea stagnalis) and a terrestrial (Helix pomatia) snail species, applying lectin histochemistry and blotting. Lectin probes that are specific for N-acetyl-glucosamine (GlcNAc) oligomers frequently appeared in anatomically different regions of the adult ganglia of both species, such as, the periganglionic sheath, the interperikaryonal space and the neuropil. Different GlcNAc residues were found to intensively glycosylate five, high-molecular weight proteins characteristic for the ECM of Lymnaea CNS and localized mainly in the interperikaryonal space. N-acetyl-galactosamine oligomers were less pronounced in the adult snail ganglia, they were detected only in the periganglionic sheath and the attached basement lamina. Apart from some similarities, the glycosylation pattern of proteins and the distribution of glycoproteins in the neuropil displayed significant differences in Lymnaea and Helix. All continuous and increasing level of and also transient presence of glycoproteins were detected during Lymnaea CNS development. Our results indicate a rich glycosylated pattern of specific proteins in the snail CNS, displaying remarkable species- and age-dependent changes which suggest the wide importance of protein glycosylation in the CNS of invertebrates.