Acquisition of species‐specific O‐linked carbohydrate chains from oviducal mucins inRana arvalis

Abstract

The extracellular matrix surrounding amphibian eggs is composed of mucin-type glycoproteins, highly O-glycosylated and plays an important role in the fertilization process. Oligosaccharide-alditols were released from the oviducal mucins of the anuran Rana arvalis by alkali-borohydride treatment in reduced conditions. Neutral and acidic oligosaccharides were fractionated by ion-exchange chromatographies and purified by HPLC. Each compound was identified by matrix assisted laser desorption ionization-time of flight (MALDI-TOF) spectrometry, NMR spectroscopy, electrospray ionization-tandem mass spectroscopy (ESI-MS/MS) and permethylation analyses. This paper reports on the structures of 19 oligosaccharide-alditols, 12 of which have novel structures. These structures range in size from disaccharide to octasaccharide. Some of them are acidic, containing either a glucuronic acid or, more frequently, a sulfate group, located either at the 6 position of GlcNAc or the 3 or 4 positions of Gal. This latter sulfation is novel and has only been characterized in the species R. arvalis. This structural analysis led to the establishment of several novel carbohydrate structures, demonstrating the structural diversity and species-specificity of amphibian glycoconjugates.Keywords: sulfated-oligosaccharides; NMR; amphibian; oviducal mucin.The amphibian eggs are surrounded by oviducal jellies, which can be structurally and chemically distinct from between species [1]. The jelly coats are made up of several concentric layers composed of mucin-type glycoproteins, highly O-glycosylated. These glycoproteins have been shown to play important roles in fertilization [2,3]. Many functions have been assigned to the egg jelly components such as sperm binding, sperm capacitation, induction of the acrosome reaction, prevention of species cross-fertilization, the block of polyspermy (anurans) and provision of a protective ionic environment for the developing embryo [4±7].Previous studies have shown a species-specific structural diversity in carbohydrate chains of amphibian egg jelly coats [8±19]. Consequently, these carbohydrate chains represent new phenotypic markers of amphibian species and from a biological point of view, can be involved in species-specific interaction gametes or in the specific host±parasite interaction [20]. In the present study, we have isolated neutral and acidic carbohydrate chains from the oviducal mucins of Rana arvalis, and determined the structure of 19 of them. M A T E R I A L S A N D M E T H O D S Sampling of jelly coat mucusEggs from R. arvalis, collected in France and Russia, were obtained from natural spawns. The jelly coat material was lyophilized. Isolation of oligosaccharide-alditolsO-linked oligosaccharides were released from the crude material by alkaline degradation in reduced conditions (1 m NaBH 4 ) to obtain stable carbohydrate chains. Total material was submitted to a cationic exchange chromatography on Dowex 50 Â 2 (200±400 mesh, H + form) to remove residual peptides. Neutral oligosaccharide-alditols ...

Mechanistic basis of adaptive maternal effects: egg jelly water balance mediates embryonic adaptation to acidity in Rana arvalis

“…With regard to amphibians, a study on the salamander Ambystoma macrodactylum indicated that sialic acid may play a role in jelly water retention (Berner and Ingermann 1990). However, mass spectrometric studies found no evidence of sialic acid in jelly of R. arvalis (Coppin et al 1999), which we confirmed for our study populations using a sialic acid detection kit (data not shown). Thus, other mechanisms are needed for variation in R. arvalis water balance in relation to pH.…”

“…However, although glycans are often a key component of egg coats, and egg coats have fundamental biological functions from fertilization to protection from environmental hazards (Menkhorst and Selwood 2008;Shu 2014), to date next to nothing is known about intra-specific glycan variation of egg coats, or the functional and evolutionary consequences of this diversity. Most studies to date have focused on quantifying glycan compositional variation among taxa (e.g., Coppin et al 1999). In a rare study, intra-specific polymorphism, equivalent of human blood groups, was found in the macromolecular composition of the egg jelly in X. laevis-but the functional consequences remained unclear (Guerardel et al 2000).…”

Molecular Cloning and Characterization of a Novel Human Galactose 3-O-Sulfotransferase That Transfers Sulfate to Galβ1→3GalNAc Residue in O-Glycans

“…The SO 3 Ϫ 33Gal structure in O-linked and N-linked glycans has been found in various glycoproteins including thyroglobulin (4 -6), meconium glycoproteins (7), respiratory mucous glycoproteins from patients with cystic fibrosis (8 -10) and chronic bronchitis (11), an ovarian cystadenoma glycoprotein (12), LS174T-HM7 colon carcinoma mucin (13), Tamm-Horsfall glycoprotein (14), sulfomucins (15), and oviducal mucins (16). Sulfated residues in these glycoproteins are attached to C-3Ј of Gal␤133/4GlcNAc, Gal␤133GalNAc, or Gal␤133Gal structure.…”

β1,4-Galactosyltransferase (β4GalT)-IV Is Specific for GlcNAc 6-O-Sulfate

“…This result indicates that the 6-O-sulfated N-acetyllactosamine structure occurs extensively. In fact, this sulfated glycan moiety has been shown to be present in various glycoproteins including ovomucin (65), glycoproteins derived from several culture cells (66), thyroglobulin (67), zona pellucida glycoproteins (68,69), gp120 of human immunodeficiency virus type 1 (70), respiratory mucins (71,72), carcinoembryonic antigen (73), hyosophorin (74), and oviducal mucins (75). 6SGN-specific ␤4GalT-IV identified in this study may be useful to elucidate the biological roles of these sulfated moieties.…”