Lectin histochemistry shows fucosylated glycoconjugates in the primordial germ cells of Xenopus embryos. |
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Authors: | Edurne Alonso Francisco J Sáez Juan F Madrid Francisco Hernández |
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Affiliation: | Department of Cell Biology and Histology, University of the Basque Country, Leioa (Vizcaya), Spain. |
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Abstract: | Previous works have shown that glycoconjugates with terminal fucose (Fuc) are located in the primordial germ cells (PGCs) of some mammals and might play a role in the migration and adhesion processes during development. The aim of this work was to identify the terminal Fuc moieties of Xenopus PGCs by means of three Fuc-binding lectins: from asparagus pea (LTA), gorse seed (UEA-I), and orange peel fungus (AAA). The histochemical procedures were also carried out after deglycosylation pretreatments: beta-elimination with NaOH to remove O-linked oligosaccharides; incubation with PNGase F to remove N-linked carbohydrate chains; and incubation with alpha(1,2)- and alpha(1,6)-fucosidase. The PGCs were always negative for LTA and UEA-I, two lectins that have the highest affinity for Fuc alpha(1,2)-linked. However, the PGCs were strongly labeled with AAA, which preferentially binds to Fuc with alpha(1,3) or alpha(1,4) linkages and to Fuc alpha(1,6)-linked to the proximal N-acetylglucosamine. There was fainter labeling with AAA when the sections were preincubated with alpha(1,6)-fucosidase, but the labeling remained strong when the sections were pretreated with alpha(1,2)fucosidase. When the beta-elimination procedure was carried out, the PGC labeling with AAA was slight. If the PNGase F incubation was performed, the PGCs remained moderately positive for AAA. These data suggest that the Xenopus PGCs have Fuc moieties in O- and N-linked oligosaccharides, including Fuc alpha(1,6) linked to the innermost GlcNAc, and that the Fuc was not in alpha(1,2)-linkage. |
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