title: Milk proteins interact with goat Binder of SPerm (BSP) proteins and decrease their binding to sperm.
abstract: Seminal plasma Binder of SPerm (BSP) proteins bind to sperm at ejaculation and promote capacitation. When in excess, however, BSP proteins damage the sperm membrane. It has been suggested that milk components of semen extenders associate with BSP proteins, potentially protecting sperm. Thus, this study was conducted to investigate if milk proteins interact with BSP proteins and reduce BSP binding to goat sperm. Using gel filtration chromatography, milk was incubated with goat seminal plasma proteins and loaded onto columns with and without calcium. Milk was also fractionated into parts containing mostly whey proteins or mostly caseins, incubated with seminal plasma proteins and subjected to gel filtration. Eluted fractions were evaluated by immunoblot using anti-goat BSP antibodies, confirming milk protein-BSP protein interactions. As determined by ELISA, milk proteins coated on polystyrene wells bound to increasing of goat BSP proteins. Far-western dot blots confirmed that BSP proteins bound to caseins and β-lactoglobulin in a concentration-dependent manner. Then, cauda epididymal sperm from five goats was incubated with seminal plasma; seminal plasma followed by milk; and milk followed by seminal plasma. Sperm membrane proteins were extracted and evaluated by immunoblotting. The pattern of BSP binding to sperm membrane proteins was reduced by 59.3 % when epididymal sperm were incubated with seminal plasma and then with skimmed milk (p < 0.05). When epididymal sperm were treated with milk followed by seminal plasma, coating of sperm with BSP proteins was not significantly reduced (57.6 %; p > 0.05). In conclusion, goat BSP proteins have an affinity for caseins and whey proteins. Milk reduces BSP binding to goat sperm, depending whether or not sperm had been previously exposed to seminal plasma. Such events may explain the protective effect of milk during goat sperm preservation.
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center and Faculty of Medicine, University of Montreal, Centre Ville, Montréal, Québec, Canada, H3C 3J7.|Department of Animal Science, Federal University of Ceara, Av. Mister Hull S/N, Campus Pici, Bloco 808, Fortaleza, CE, Brazil, 60021-970.
authors.forename: Erika Bezerra
authors.initials: EB
authors.lastname: de Menezes
authors.affiliation: Department of Animal Science, Federal University of Ceara, Av. Mister Hull S/N, Campus Pici, Bloco 808, Fortaleza, CE, Brazil, 60021-970.
authors.forename: Mauricio
authors.initials: M
authors.lastname: van Tilburg
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center and Faculty of Medicine, University of Montreal, Centre Ville, Montréal, Québec, Canada, H3C 3J7.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Plante
authors.affiliation: Department of Animal Science, Federal University of Ceara, Av. Mister Hull S/N, Campus Pici, Bloco 808, Fortaleza, CE, Brazil, 60021-970.
authors.forename: Rodrigo V
authors.initials: RV
authors.lastname: de Oliveira
authors.affiliation: Department of Animal Science, Federal University of Ceara, Av. Mister Hull S/N, Campus Pici, Bloco 808, Fortaleza, CE, Brazil, 60021-970. amoura@ufc.br.
authors.forename: Arlindo A
authors.initials: AA
authors.lastname: Moura
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center and Faculty of Medicine, University of Montreal, Centre Ville, Montréal, Québec, Canada, H3C 3J7.
authors.forename: Puttaswamy
authors.initials: P
authors.lastname: Manjunath
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000494:pharmacology; D002850:Chromatography, Gel; D004797:Enzyme-Linked Immunosorbent Assay; D004822:Epididymis / Q000378:metabolism; D006041:Goats / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008894:Milk Proteins / Q000378:metabolism*; D008954:Models, Biological; D066329:Protein Aggregates / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D029607:Seminal Vesicle Secretory Proteins / Q000378:metabolism*; D013094:Spermatozoa / Q000187:drug effects / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D008894:Milk Proteins; D066329:Protein Aggregates; D029607:Seminal Vesicle Secretory Proteins; D002118:Calcium
keywords: Binder of SPerm proteins; Goat seminal plasma; Milk proteins; Protein–protein interaction; Sperm protection