title: Desialylation of core type 1 O-glycan in the equine embryonic capsule coincides with immobilization of the conceptus in the uterus.
abstract: During the second and third weeks of pregnancy, the equine conceptus expands rapidly while it is enclosed within a glycan capsule. Around day 16 of gestation, the conceptus loses its mobility in the uterus by a process termed 'fixation', coinciding with various changes in the capsule. Here, we compared the structure of the carbohydrate moieties expressed by the capsule during pre- and post-fixation periods. The glycan structures were studied by chemical analyses in combination with mass spectrometry. Capsule material from conceptuses collected before fixation (days 13-16) was observed to carry a sialylated core type 1 O-linked glycan, Neu5Ac-(2-->3)-Gal-(1-->3)-GalNAc-(1-->Ser/Thr. By comparison, analysis of post-fixation capsules (days 17-19) revealed a desialylated core type 1, Gal-(1-->3)-GalNAc-(1-->Ser/Thr. The equine embryonic capsule also furnished 4-substituted GlcNAc, 4-substituted Glc and 2,3,4,6-tetrasubstituted Glc residues, the concentrations of which did not change between pre- and post-fixation stages. The loss of sialic acid from the sialylated core type 1 in the capsule appears to be directly related to successful fixation of the conceptus, and thus critical to the continuance of pregnancy in horses.
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, ON, Canada N1G 2W1.
authors.forename: Sharif
authors.initials: S
authors.lastname: Arar
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Chan
authors.forename: Bette A
authors.initials: BA
authors.lastname: Quinn
authors.forename: Rudolf O
authors.initials: RO
authors.lastname: Waelchli
authors.forename: M Anthony
authors.initials: MA
authors.lastname: Hayes
authors.forename: Keith J
authors.initials: KJ
authors.lastname: Betteridge
authors.forename: Mario A
authors.initials: MA
authors.lastname: Monteiro
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002849:Chromatography, Gas; D005260:Female; D005306:Fertilization; D006023:Glycoproteins / Q000737:chemistry; D006736:Horses; D009005:Monosaccharides / Q000032:analysis; D011134:Polysaccharides / Q000032:analysis* / Q000737:chemistry*; D011247:Pregnancy; D014599:Uterus / Q000502:physiology*
chemical_list: D006023:Glycoproteins; D009005:Monosaccharides; D011134:Polysaccharides