Cryopreservation in Different Concentrations of Glycerol Alters Boar Sperm and Their Membranes
2001; Wiley; Volume: 22; Issue: 6 Linguagem: Inglês
10.1002/j.1939-4640.2001.tb03436.x
ISSN2047-2927
AutoresM.M. Buhr, P.S. Fiser, Janice L. Bailey, E.F. Curtis,
Tópico(s)Reproductive biology and impacts on aquatic species
ResumoABSTRACT: To test the hypothesis that glycerol would concomitantly affect sperm membrane structure and the function of the intact cells, boar semen (4 ejaculates from 4 boars) was cryopreserved in an egg yolk extender with 0%, 2%, 4%, or 8% glycerol in 0.5‐mL straws using previously derived optimal cooling and thawing rates. Increasing glycerol concentrations increased spermatozoal progressive motility immediately after thawing and after 2 hours at 43°C, but decreased the percentage of sperm with normal acrosomal morphology. The mathematical products of the motility and acrosomal integrity scores (MOT x NAR index) were low in 0% and 8% glycerol, and significantly higher in 2% and 4% glycerol. The fluidity of sperm‐head plasma membranes, a measure of molecular interaction, was assessed with the lipid probes trans ‐parinaric acid and cis ‐parinaric acid (tPNA, cPNA), during a 2.5‐hour incubation with or without 1 mM Ca 2+ . Membrane fluidity detected by each probe differed significantly, indicating the presence of at least 2 domains whose constituent molecules had unique dynamics. Behavior of each domain was radically altered by cryopreservation. Increasing glycerol concentration caused a variably faster loss of fluidity in the cPNA domain, and had highly variable effects on fluidity change over time in the tPNA domain. Normal acrosomal ridge (NAR) and the MOT x NAR index correlated significantly with the fluidity of the more mobile cPNA domain (±1mM Ca 2+ ), supporting the hypothesis of an interrelationship of glycerol concentration during cryopreservation with sperm membrane structure and cell function. The MOT x NAR index may be a useful guide in choosing optimal cryoprotectant concentrations.
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