Organization of carbohydrate components in the egg-jelly layers of the newt, Cynops pyrrhogaster

Abstract

The egg-jelly of C. pyrrhogaster is composed of six layers: the J0, J1, J2, J3, J4 and sticky layers (from the innermost to outermost). In this study, we investigated the localizations of carbohydrate moieties in the egg-jelly using the FITC-conjugated N-acetylgalactosamine/galactose, glucose/mannose, N-acetylglucosamine and fucose group lectins. Eight of nine kinds of tested lectins belonging to every group were bound to the J1 and J3 layers, while Dolichos biforus agglutinine (DBA) were bound only to the J0 and the J2 layers. Though Triticum vulgaris agglutinine was bound to all the four layers, the binding was inhibited only in the J0 and J2 layers by N-acetylglucosamine. Five kinds of lectins belonging to every group except for the fucose group uniformly bound to the J4 layer, while DBA and Arachis hypogaea agglutinine did not. Ulex europaeus agglutinine and Glycine max agglutinine bound only to the inner portion of the layer. These results suggest that the inner four layers are composed of two types of layers and that the J4 layer has a unique carbohydrate composition. In the oviduct, most lectins bound to the regions where the egg-jelly layers bound by the lectins were added. However, DBA bound to the anteriormost portion of the regions where the layers next to those bound by DBA was added. These results suggest that carbohydrate components of egg-jelly layers are fundamentally added in the corresponding regions of the oviduct while some molecules may be added after the matrices of the layer have already been accumulated.