Lectin binding sites in inner ear membranes: further observations.

Fluorescein isothiocyanate-conjugated or peroxidase-labelled lectins known to react with the hexose of glycoproteins were used to study the glycoconjugates composition of otolithic membranes and ampullar cupulae in embryos and adult specimens of reptiles (the lizard Podarcis s. sicula) and mammals (mouse and guinea pig). Each inner ear membrane has different lectin binding sites thus showing the presence of different types glycoconjugates. In fact in the ampullar cupulae are absent sites for Umulus Polyphemus lectin (sialic add) and for Lotus tetragonolobus lectin (L-fucose) which are present in the otolithic membranes. The membranes generally do not show differences between the species. Differences are instead observed in the same animal (Podarcis s. sicula) between calcite and aragonite otoliths. In fact only in the calcite matrix binding sites for the Lotus tetragonolobus agglutinin (L-fucose) are present. The results confirm the existence also in reptiles and mammals of differences in glycoconjugates components in the various structure: i.e. between otolithic membranes and ampullar cupulae and between calcite and aragonite otoliths.