title: Selected proteins of "prostasome-like particles" from epididymal cauda fluid are transferred to epididymal caput spermatozoa in bull.
abstract: During epididymal transit, spermatozoa acquire selected proteins secreted by epithelial cells. We recently showed that P25b, a protein with predictive properties for bull fertility, is transferred from prostasome-like particles present in the cauda epididymal fluid (PLPCd) to the sperm surface. To further characterize the interactions between PLPCd and epididymal spermatozoa, PLPCd were prepared by ultracentrifugation of bull epididymal fluid, then surface-exposed proteins were biotinylated and coincubated in different conditions with caput epididymal spermatozoa. Western blot analysis revealed that only selected proteins are transferred from PLPCd to spermatozoa. MALDI-TOF analysis revealed that these transferred proteins are closely related. The pattern of distribution of the PLPCd transferred varied from one sperm cell to the other, with a bias toward the acrosomal cap. This transfer appeared to be temperature sensitive, being more efficient at 32-37 degrees C than at 22 degrees C. Transfer of PLPCd proteins to spermatozoa was also pH dependant, the optimal pH for transfer being 6.0-6.5. The effect of divalent cations on PLPCd protein transfer to caput spermatozoa was investigated. Whereas Mg(2+) and Ca(2+) have no effect on the amount of proteins remaining associated with spermatozoa following coincubation, Zn(2+) had a beneficial effect. These results are discussed with regard to the function of PLPCd in epididymal sperm maturation.
authors.affiliation: Centre de Recherche en Biologie de la Reproduction and Département d'Obstétrique-Gynécologie, Faculté de Médecine, Université Laval, 2705 Boulevard Laurier, Ste-Foy, Quebec, PQ, Canada G1V 4G2.
authors.forename: Gilles
authors.initials: G
authors.lastname: Frenette
authors.forename: Carl
authors.initials: C
authors.lastname: Lessard
authors.forename: Robert
authors.initials: R
authors.lastname: Sullivan
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000502:physiology; D002417:Cattle; D002469:Cell Separation; D003546:Cysteine Endopeptidases / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D003720:Densitometry; D004591:Electrophoresis, Polyacrylamide Gel; D004822:Epididymis / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008274:Magnesium / Q000502:physiology; D008297:Male; D008565:Membrane Proteins / Q000737:chemistry / Q000302:isolation & purification; D009097:Multienzyme Complexes / Q000032:analysis / Q000378:metabolism* / Q000502:physiology; D046988:Proteasome Endopeptidase Complex; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013079:Sperm Maturation / Q000502:physiology; D013094:Spermatozoa / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D015032:Zinc / Q000502:physiology
chemical_list: D008565:Membrane Proteins; D009097:Multienzyme Complexes; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D008274:Magnesium; D015032:Zinc; D002118:Calcium