title: Histochemical identification of sialylated glycans in Xenopus laevis testis.
abstract: Carbohydrate chains of glycoprotein and glycosphingolipids are highly diverse molecules involved in many cell functions, including cell recognition, adhesion and signalling. Sialylated glycans are of special interest because the terminal position of sialic acid (NeuAc) in glycans linked by different ways to subterminal monosaccharides has been shown to be involved in several biological processes, as occurs with gangliosides, which have been reported as being essential in spermatogenesis in mammals. Some glycan-binding proteins, the lectins, which specifically recognize glycan sequences, have been extensively used to characterize tissue and cell carbohydrates by means of cytochemical techniques. The aim of the present work was to determine the presence of NeuAc by means of histochemical techniques in the testis of Xenopus laevis, an animal model widely used in cell and molecular biology research. However, considering that some NeuAc-binding lectins are capable of binding to N-acetylglucosamine (GlcNAc), other GlcNAc-binding lectins were also assayed. The results showed that NeuAc is mainly expressed in the interstitium, and only a weak labelling in the male germ cells was observed. Most NeuAc was located in O-linked oligosaccharides, but some masked NeuAc in N-glycans were identified in primary and secondary spermatogonia and spermatocytes. By contrast, GlcNAc was widely expressed in all germ cell types. Deglycosylative pre-treatments suggest that both N- and O-glycans and/or glycolipids could be responsible for this labelling. In addition, GlcNAc in O-linked oligosaccharides has been identified in spermatogonial cells. The acrosome of spermatids was always negative. Variations of glycan expression have been found in different cell types, suggesting that glycosylation is modified during spermatogenetic development.
authors.affiliation: Department of Cell Biology and Histology, UFI11/44, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, Leioa, Spain.
authors.forename: Galder
authors.initials: G
authors.lastname: Valbuena
authors.forename: Edurne
authors.initials: E
authors.lastname: Alonso
authors.forename: María Martínez
authors.initials: MM
authors.lastname: de Ubago
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Madrid
authors.forename: Lucio
authors.initials: L
authors.lastname: Díaz-Flores
authors.forename: Francisco José
authors.initials: FJ
authors.lastname: Sáez
mesh_terms: D000818:Animals; D006651:Histocytochemistry / Q000379:methods; D037102:Lectins; D008297:Male; D019158:N-Acetylneuraminic Acid / Q000032:analysis*; D011134:Polysaccharides / Q000032:analysis*; D013737:Testis / Q000737:chemistry*; D014982:Xenopus laevis
chemical_list: D037102:Lectins; D011134:Polysaccharides; D019158:N-Acetylneuraminic Acid