Lectin binding sites in the inner ear membranes. A dettailed analysis of the otolithic membranes.

FITC-labelled lectins with binding specificity to the hexose components of glycoconjugates were used to demonstrate structural difference in the glycoprotein composition of otolithic membranes and ampullar cupulae in chicken embryos, tadpoles and adult specimens of Rana esculenta. While the calcitic otolithic membranes and ampullar cupulae of frog and of chicken embryos showed the same lectin receptor patterns, different lectin binding sites are present, independently from the species, in the otolithic membranes and ampullar cupulae: in the ampullar cupulae binding sites for LPA and UEA I are absent. Differences are also found between calcite and aragonite otoliths, even in the same species (Rana esculenta): only the calcite otoliths contain binding sites for the UEA I. The results indicate the existence of heterogeneous glycoconjugates components, with variations in the degree of glycosilation of their oligosaccharide chains, in the different structures: between otolithic membranes and ampullar cupulae and between calcite and aragonite otoliths.