Identification of fucosylated glycoconjugates in Xenopus laevis testis by lectin histochemistry

Abstract

Glycoconjugates play roles in many physiological and pathological processes. Previous works have shown important functions mediated by glycans in spermatogenesis, and the carbohydrate composition of testis has been studied by several approaches, including lectin-histochemical methods. However, the testis of Xenopus laevis, an animal model extensively employed in biochemical, cell and developmental research, has not yet been analysed. The aim of this work was to carry out a histochemical study of the fucose (Fuc)-containing glycoconjugates of Xenopus testis by means of lectins, combined with deglycosylation pretreatments. Four Fuc-binding lectins were used: orange peel (Aleuria aurantia) lectin (AAL), gorse seed (Ulex europaeus) agglutinin-I (UEA-I), fresh water eel (Anguilla anguilla) agglutinin (AAA), and asparagus pea (Lotus tetragonolobus) agglutinin (LTA), each recognizing different forms of fucosylated glycans. Labelling with UEA-I, which preferably binds Fucalpha(1,2) containing oligosaccharides, did not show any appreciable staining. LTA, specific for Fucalpha(1,3), and AAA, which binds Fucalpha(1,2), labelled spermatocytes and spermatids, but no labelling was seen when the histochemical procedure was carried out after either beta-elimination (which removes O-linked oligosaccharides) or incubation with PNGase F (which removes N-linked oligosaccharides), suggesting that fucosylated glycans are of both N- and O-linked types. AAL, which has its highest affinity to Fucalpha(1,6), but also recognizes Fucalpha(1,2) and Fucalpha(1,3), labelled the whole testis, and the staining remained when the histochemical method was performed after either beta-elimination or incubation with PNGase F. Labelling with AAL could be explained by the fact that this lectin could be binding to diverse fucosylated glycans in N- and O-glycans, and even in glycolipids. The importance of these glycans is discussed.

Lectin Histochemistry as a Tool to Identify Apoptotic Cells in the Seminiferous Epithelium of Syrian Hamster (Mesocricetus auratus) Subjected to Short Photoperiod

“…Lectin histochemical techniques have been widely used to study the pattern of the glycoconjugates present in the cells of the seminiferous epithelium in many species of vertebrate, including amphibians (Valbuena et al. , ,b), fish (Liguoro et al. ; Desantis et al.…”

“…Lectin histochemical techniques have been widely used to study the pattern of the glycoconjugates present in the cells of the seminiferous epithelium in many species of vertebrate, including amphibians (Valbuena et al 2010(Valbuena et al , 2011a, fish (Liguoro et al 2004;Desantis et al 2010), birds (Ballesta et al 1991;Bakst et al 2007;Pel aez and Long 2008), mammals (Arya and Vanha-Perttula 1985;Calvo et al 2000;Pinart et al 2001;Morales et al 2002;Desantis et al 2006;Parillo et al 2012) and humans (Arenas et al 1998). This histochemical technique has recently been used to identify changes in the pattern of glycoconjugates of various cell types in apoptosis (Taatjes et al 2008), in particular lectins with affinity for a-D-mannose and b-D-galactose (Bilyy et al 2004).…”

Microvascular anatomy of testes in the adult pipid frog, Xenopus laevis Daudin: A scanning electron microscopic study of vascular corrosion casts

“…Xenopus laevis increasingly serves as an in-vitro and in-vivo model for the screening of Endocrine Disruptor Chemicals (EDCs) that affect hypophysis and thyroid glands as well as gonads, and as a model animal species to study reproductive toxicity of phytoestrogens (Cong et al, 2006). For these reasons, gonadal histomorphology (Cevasco et al, 2008;Kalt, 1976) and histochemistry (Valbuena et al, 2012(Valbuena et al, , 2010Valbuena, Alonso, Diaz Flores, et al, 2011;Valbuena, Alonso, Madrid, & Diaz Flores, and Saez, 2011b) are well documented in adult Xenopus. However, only one of the above-mentioned studies has paid attention to the testicular blood vessels (Cevasco et al, 2008).…”

“…Anatomy, morphology, fine structure, histochemistry and endocrine regulation of the anuran testes have been studied in great detail (e.g., Lofts, ; Duellman & Trueb, ; Valbuena, Madrid, Hernandez, & Saez, ; Valbuena, Alonso, Diaz Flores, Madrid, & Saez, ; Valbuena et al, ; Villagra, Ramos, Cisint, Crespo, & Fernandez, ). However, little is known on the vascular anatomy of the anuran testes.…”

Histochemistry and cell biology: the annual review 2010

“…That is why it was quite surprising that glycoconjugate research has not been conducted so far in Xenopus laevis (an extensively employed animal model). Using four diVerent Fuc-binding lectins, proteins containing deWned carbohydrate-recognition sites, Valbuena et al (2010) addressed this shortfall, characterizing distribution of such molecules in Xenopus testis. With labelling of spermatocytes and spermatids by the orange peel (Aleuria aurantia) lectin and the asparagus pea (Lotus tetragonolobus) agglutinin and the Wnding through deglycosylation pretreatments that such fucosylated glycans were of N-and O-linked types, Wrst steps towards gaining informations regarding the nature and involvement of glycoconjugates in testicular function have been made.…”