Characterization of olfactory receptor organs in Xenopus laevis Daudin

Xenopus laevis is highly suitable for studying the mechanisms of olfactory reception for water-soluble odorants and for airborne odorants. However, the functional differences of cells and component protein molecules in the olfactory receptors of Xenopus have remained obscure. In recent studies, the patterns of sugar residues expressed on the cell surface have been utilized to analyze the characteristics of neurons, because the sugar chains in neurons play very important roles in targeting and cell-to-cell communication. In this study, we have determined the distribution of sugar residues and glycoproteins in the olfactory receptor organs of Xenopus using lectins as labeling agents, and characterized the receptors of water-soluble odorants and of airborne odorants. The results of lectin histochemical analysis show distributional differences of GlcNAc, GalNAc and mannose between the middle chamber and the lateral chamber of the main nasal cavity. Furthermore, a 65 kDa glycoprotein containing mannose, GlcNAc and GalNAc was specifically detected in the medial chamber of the main cavity epithelium in receptor organs of airborne odorants by SDS-PAGE and lectin blotting. The characteristics of the epithelia demonstrated in this study should further our understanding of the functional differences between the receptors of water-soluble odorants and of airborne odorants at the molecular level.