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Valbuena G, Madrid JF, Martínez de Ubago M, Gómez-Santos L, Alonso E, Díaz-Flores L, Sáez FJ. N-Glycans in Xenopus laevis testis characterised by lectin histochemistry. Reprod Fertil Dev 2014; 28:337-48. [PMID: 25482090 DOI: 10.1071/rd14077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 06/03/2014] [Indexed: 11/23/2022] Open
Abstract
Analysis of glycan chains of glycoconjugates is difficult because of their considerable variety. Despite this, several functional roles for these glycans have been reported. N-Glycans are oligosaccharides linked to asparagine residues of proteins. They are synthesised in the endoplasmic reticulum (ER) in a unique way, and later modified in both the ER and Golgi apparatus, developing different oligosaccharide chains. An essential role for complex N-glycans in mammalian spermatogenesis has been reported. The aim of the present study was to analyse the N-glycans of the Xenopus laevis testis by means of lectin histochemistry. Five lectins were used that specifically recognise mannose-containing and complex glycans, namely Galanthus nivalis agglutinin (GNA) from snowdrops, concanavalin A (Con A) from the Jack bean, Lens culinaris agglutinin (LCA) from lentils and Phaseolus vulgaris erythroagglutinin (PHA-E) and P. vulgaris leukoagglutinin (PHA-L) from the common bean. GNA and Con A labelled the interstitium and most of the germ cell types, whereas LCA and PHA-E showed affinity only for the interstitium. A granular cytoplasmic region was labelled in spermatogonia and spermatocytes by GNA and PHA-L, whereas GNA and LCA labelled a spermatid region that is probably associated with the centriolar basal body of the nascent flagellum. There was no specific labelling in the acrosome. Some unexpected results were found when deglycosylative pretreatments were used: pre-incubation of tissue sections with peptide N glycosidase F, which removes N-linked glycans, reduced or removed labelling with most lectins, as expected. However, after this pretreatment, the intensity of labelling remained or increased for Con A in the follicle (Sertoli) and post-meiotic germ cells. The β-elimination procedure, which removes O-linked glycans, revealed new labelling patterns with GNA, LCA and PHA-L, suggesting that some N-glycans were masked by O-glycans, and thus they became accessible to these lectins only after removal of the O-linked oligosaccharides. The functional role of the glycan chains identified could be related to the role of N-glycans involved in mammalian spermatogenesis reported previously.
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Affiliation(s)
- Galder Valbuena
- Department of Cell Biology and Histology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, B° Sarriena s/n, E-48940 Leioa, Vizcaya, Spain
| | - Juan Francisco Madrid
- Department of Cell Biology and Histology, School of Medicine, Regional Campus of International Excellence 'Campus Mare Nostrum', University of Murcia, E-30100 Espinardo, Murcia, Spain
| | - María Martínez de Ubago
- Department of Cell Biology and Histology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, B° Sarriena s/n, E-48940 Leioa, Vizcaya, Spain
| | - Laura Gómez-Santos
- Department of Cell Biology and Histology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, B° Sarriena s/n, E-48940 Leioa, Vizcaya, Spain
| | - Edurne Alonso
- Department of Cell Biology and Histology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, B° Sarriena s/n, E-48940 Leioa, Vizcaya, Spain
| | - Lucio Díaz-Flores
- Department of Anatomy, Pathology, Histology and Radiology, University of La Laguna, Ofra-La Cuesta s/n, La Laguna, E-38071 Tenerife, Spain
| | - Francisco J Sáez
- Department of Cell Biology and Histology, School of Medicine and Dentistry, University of the Basque Country UPV/EHU, B° Sarriena s/n, E-48940 Leioa, Vizcaya, Spain
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