title: Combined albumin and bicarbonate induces head-to-head sperm agglutination which physically prevents equine sperm-oviduct binding.
abstract: In many species, sperm binding to oviduct epithelium is believed to be an essential step in generating a highly fertile capacitated sperm population primed for fertilization. In several mammalian species, this interaction is based on carbohydrate-lectin recognition. D-galactose has previously been characterized as a key molecule that facilitates sperm-oviduct binding in the horse. We used oviduct explant and oviduct apical plasma membrane (APM) assays to investigate the effects of various carbohydrates; glycosaminoglycans; lectins; S-S reductants; and the capacitating factors albumin, Ca(2+) and HCO3(-) on sperm-oviduct binding in the horse. Carbohydrate-specific lectin staining indicated that N-acetylgalactosamine, N-acetylneuraminic acid (sialic acid) and D-mannose or D-glucose were the most abundant carbohydrates on equine oviduct epithelia, whereas D-galactose moieties were not detected. However, in a competitive binding assay, sperm-oviduct binding density was not influenced by any tested carbohydrates, glycosaminoglycans, lectins or D-penicillamine, nor did the glycosaminoglycans induce sperm tail-associated protein tyrosine phosphorylation. Furthermore, N-glycosidase F (PNGase) pretreatment of oviduct explants and APM did not alter sperm-oviduct binding density. By contrast, a combination of the sperm-capacitating factors albumin and HCO3(-) severely reduced (>10-fold) equine sperm-oviduct binding density by inducing rapid head-to-head agglutination, both of which events were independent of Ca(2+) and an elevated pH (7.9). Conversely, neither albumin and HCO3(-) nor any other capacitating factor could induce release of oviduct-bound sperm. In conclusion, a combination of albumin and HCO3(-) markedly induced sperm head-to-head agglutination which physically prevented stallion sperm to bind to oviduct epithelium.
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands baleeman.leemans@ugent.be.
authors.forename: Bart
authors.initials: B
authors.lastname: Leemans
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Bart M
authors.initials: BM
authors.lastname: Gadella
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Tom A E
authors.initials: TA
authors.lastname: Stout
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Edita
authors.initials: E
authors.lastname: Sostaric
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Catharina
authors.initials: C
authors.lastname: De Schauwer
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Hilde
authors.initials: H
authors.lastname: Nelis
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: Hoogewijs
authors.affiliation: Department of ReproductionObstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, BelgiumDepartments of Farm Animal HealthBiochemistry and Cell BiologyEquine SciencesFaculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors.forename: Ann
authors.initials: A
authors.lastname: Van Soom
mesh_terms: D000418:Albumins / Q000494:pharmacology*; D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology*; D002021:Buffers; D005260:Female; D006736:Horses; D008297:Male; D010057:Oviducts / Q000187:drug effects / Q000378:metabolism*; D013073:Sperm Agglutination / Q000187:drug effects*; D013075:Sperm Capacitation / Q000187:drug effects*; D013077:Sperm Head / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000418:Albumins; D001639:Bicarbonates; D002021:Buffers