title: The spermatozoa of the dasyurid marsupial, Sminthopsis crassicaudata, are highly susceptible to cold shock.
abstract: Since the late 1970s research has suggested that marsupial spermatozoa did not suffer cold shock. We have re-examined cold shock to investigate problems with freezing of spermatozoa from a dasyurid marsupial, the fat-tailed dunnart (Sminthopsis crassicaudata). Epididymal spermatozoa were rapidly cooled to 0.5 degrees C in a pre-cooled tube held in an iced-water slurry. Upon re-warming all spermatozoa were immotile and the addition of 10% or 20% egg yolk to the sperm medium had no beneficial effect. Spermatozoa that were rapidly cooled to 4 degrees C maintained only 2% motility when re-warmed but the addition of at least 10% egg yolk was beneficial and upon re-warming greater than 65% of the initial motility was maintained. In order to achieve motile spermatozoa at 0 degrees C, controlled-rate cooling at 0.5 degrees C min(-1) was examined. In the absence of egg yolk there was a significant decline in the percentage of motile spermatozoa below 4 degrees C. However, the inclusion of at least 10% egg yolk resulted in no loss of motility in spermatozoa cooled to 0 degrees C. This is the first experimental study indicating that spermatozoa from a marsupial are highly susceptible to cold shock and that the impact of rapid chilling can be mitigated by the addition of 10% egg yolk. The ability to successfully cool the spermatozoa of S. crassicaudata to 0 degrees C may have an important role in future studies examining dasyurid sperm cryopreservation.
authors.affiliation: School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia. natashaczarny@hotmail.com
authors.forename: N A
authors.initials: NA
authors.lastname: Czarny
authors.forename: J C
authors.initials: JC
authors.lastname: Rodger
mesh_terms: D000818:Animals; D003080:Cold Temperature / Q000009:adverse effects*; D015925:Cryopreservation / Q000379:methods*; D008297:Male; D008394:Marsupialia; D012662:Semen Preservation / Q000379:methods*; D013094:Spermatozoa