á-N-acetylglucosamine-linked O-glycans of sialoglycoproteins (Tc-mucins) from Trypanosoma cruzi Colombiana strain

Trypanosoma cruzi sialoglycoproteins (Tc-mucins) are mucin-like molecules linked to a parasite membrane via a glycosylphosphatidylinositol anchor. We previously determined the structures of Tc-mucin O-glycan domains from several T. cruzi strains and observed significant differences among them. We now report the amino acid content and structure of Tc-mucin O-glycan chains from T. cruzi Colombiana, a strain resistant to common trypanocidal drugs. Amino acid analysis demonstrated the predominance of threonine residues (42%) and helped to identify the O-glycans as belonging to a Tc-mucin family that contain a ²-galactofuranose (²-Galf) residue attached to an á-N-acetylglucosamine (á-GlcNAc) O-4, with the most complex glycan, a pentasaccharide-GlcNAc-ol with a branched trigalactopyranose chain, on the GlcNAc O-6. The presence of ²-Galf on O-glycans from T. cruzi Colombiana mucins supports the use of glycosylation as a phylogenetic marker for the classification of Colombiana in the T. cruzi I group.

Recognition of n-acetylglucosamine (GLyNAc) and poly-i-acetyllactosamine residues in vessels of the rat pineal gland

Las lectinas son proteínas que contienen áreas singulares para el reconocimiento de secuencias de azúcares en los glicoconjugados. La lecitina del tomate Lycopersicon esculentum (LEL) es capaz de reconocer específicamente los residuos de N-acetil-glucosamina (Gly-Nac) y poli-N-acetil-lactosamina. Utilizamos la técnica histoquímica para LEL conjugada a la biotina con el propósito de investigar en la glándula pineal de ratones adultos y durante el desarrollo, las estructuras morfológicas capaces de unirse a esta lecitina. Nuestros resultados experimentales mostraron un material de coloración por la LEL, solamente en la superficie de las células endoteliales de todos los vasos sanguíneos y en todas las regiones de la glándula. La excepción ocurrió en los ratones con un día pos-natal (PN1), donde solamente los vasos de la región más periférica de la glándula presentaban coloración marrón amarillenta por la LEL, pero ninguno presentaba esta coloración en la región más central de la glándula. La reacción apareció especialmente en el espacio interno de las pseudo-rosetas, demostrando así que este espacio está, seguramente, representado por un vaso.

Histochemical detection of sugar residues in lizard teeth (Liolaemus gravenhorsti): a lectin-binding study

The structural diversity of the many oligosaccharide chains of surface glycoconjugates renders them likely candidates for modulators of cell-interactions, cellular movements, differentiation, and cellular recognition. A selection of different lectins was used to investigate the appearance of cellular distribution and changes in sugar residues during tooth development in the polyphyodont lizard, Liolaemus gravenhorsti. Lectins from three groups were used: (1) N-acetylgalactosamine specificity: BS-1, PNA, RCA-120; (2) N-acetylglucosamine specificity: ECA; and (3) fucose specificity: UEA 1 and LTA.. Digital images were processed using Scion Image. Grayscale graphics in each image were obtained. The lectins used showed a strong, wide distribution of the L-fucose and N-acetylgalactosamine at the cell surface and in the cytoplasm of multinucleate odontoclast cell, while mononuclear odontoclast cells showed no binding, suggesting some roles that the residues sugar might play in the resorption of dentine or with multinucleation of odontoclast after the attachment to the dentine surface in this polyphyodont species. Further studies must be planned to determine the specific identities of these glycoconjugates,and to elucidate the roles played by these sugar residues in the complex processes related to odontogenesis in polyphyodont species.