title: Spermatozoa in the sperm-peak-fraction of the boar ejaculate show a lower flow of Ca(2+) under capacitation conditions post-thaw which might account for their higher membrane stability after cryopreservation.
abstract: Boar spermatozoa collected in the ejaculate sperm peak-portion (P1, first 10 mL of the sperm-rich fraction, SRF), had shown a higher resilience to freezing and thawing compared to spermatozoa from the rest of the ejaculate (2nd portion of the SRF plus the post-sperm-rich fraction, PSRF), even when using a simplified freezing technique, as long as spermatozoa were incubated in their own seminal plasma (SP). This experiment studied the stability of P1- and SRF-P1 boar spermatozoa frozen in MiniFlatPacks (MFP), post-thaw, using flow cytometry. Since spermatozoa from either portion showed similar cryosurvival and low proportions of unstable membranes (<3%, annexin-V/propidium iodide staining), and only a tendency for SRF-P1 live spermatozoa to depict acrosome exocytosis (FITC-PNA/PI/H33342); they were explored for Ca(2+) contents using a Fluo-4 probe under in vitro capacitating conditions (mBO+ medium), as well they were tested for their ability to sustain a short Ca(2+)-ionophore (A23187) in vitro challenge. The proportions of live spermatozoa depicting high Ca(2+)-levels were initially <2% but increased over incubation time, particularly in SRF-P1(P<0.05), while proportions of live spermatozoa with low Ca(2+)-levels were basically constant over incubation time (~11-14%), for either portion. Incubation in capacitation medium did not modify the proportions of low-Ca(2+) but dramatically increased the proportions of high-Ca(2+) spermatozoa (P<0.001) already after 15 min exposure, highest for SRF-P1 spermatozoa. While the proportion of live spermatozoa with intact acrosome was significantly decreased among SRF-P1 (P<0.001), that of P1-spermatozoa remained unchanged, probably owing to the lowest relative content of cytosolic Ca(2+). The results suggest that spermatozoa in the P1-portion are more resilient to express acrosome exocytosis post-thaw compared to those bathing in the rest of the SRF-fraction when cryopreserved using a simplified technique, in MFPs.
authors.affiliation: Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Md Sharoare
authors.initials: MS
authors.lastname: Hossain
authors.forename: Anders
authors.initials: A
authors.lastname: Johannisson
authors.forename: Amanda Pimenta
authors.initials: AP
authors.lastname: Siqueira
authors.forename: Margareta
authors.initials: M
authors.lastname: Wallgren
authors.forename: Heriberto
authors.initials: H
authors.lastname: Rodriguez-Martinez
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000502:physiology*; D015925:Cryopreservation / Q000662:veterinary*; D004542:Ejaculation / Q000502:physiology; D005615:Freezing; D008297:Male; D012662:Semen Preservation / Q000379:methods; D013075:Sperm Capacitation / Q000502:physiology*; D013076:Sperm Count; D013094:Spermatozoa / Q000502:physiology*; D013552:Swine / Q000502:physiology*
chemical_list: D002118:Calcium