title: Seminal plasma proteins protect flow-sorted ram spermatozoa from freeze-thaw damage.
abstract: Seminal plasma improves the functional integrity of compromised ram spermatozoa but has been reported to be toxic to sorted spermatozoa. The present study attempted to clarify this paradoxical effect and improve the functional integrity of spermatozoa following sorting and cryopreservation. The in vitro function of sorted spermatozoa (motility characteristics and membrane integrity) was examined after supplementation with differing concentrations and protein fractions of seminal plasma at various stages of the sorting and freezing process. For all experiments, spermatozoa (two males, n=four ejaculates per male) were processed through a high-speed flow cytometer before cryopreservation, thawing and incubation for 6 h (37 degrees C). Supplementation of crude seminal plasma (CP), its low molecular weight fraction (LP; <10 kDa) or protein-rich fraction (SPP; >10 kDa), immediately before freezing improved the functional integrity of sorted spermatozoa compared with no supplementation (control), whereas supplementation after thawing had no effect for CP and LP. The protective effect of seminal plasma was not altered by increasing the amount of protein supplementation. No toxic effect of CP, SPP or LP was evident even when supplemented at high protein concentrations. It is concluded that seminal plasma protein, if added to ram spermatozoa after sorting and before freezing, can improve post-thaw sperm quality and consequently the efficiency of sorting. This effect is most likely related to protection of the spermatozoa during freeze-thawing.
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Sydney, NSW 2006, Australia. tamaral@vetsci.usyd.edu.au
authors.forename: T
authors.initials: T
authors.lastname: Leahy
authors.forename: J I
authors.initials: JI
authors.lastname: Marti
authors.forename: G
authors.initials: G
authors.lastname: Evans
authors.forename: W M C
authors.initials: WM
authors.lastname: Maxwell
mesh_terms: D000818:Animals; D002469:Cell Separation / Q000662:veterinary*; D002470:Cell Survival / Q000187:drug effects; D015925:Cryopreservation / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry / Q000662:veterinary*; D008297:Male; D012099:Reproductive Techniques / Q000662:veterinary; D012662:Semen Preservation / Q000009:adverse effects / Q000662:veterinary*; D029589:Seminal Plasma Proteins / Q000494:pharmacology*; D012756:Sheep; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects* / Q000473:pathology
chemical_list: D003451:Cryoprotective Agents; D029589:Seminal Plasma Proteins