Acrosome stability in the spermatozoa of dasyurid marsupials
N. A. Czarny A B , K. E. Mate A and J. C. Rodger AA Marsupial Research Laboratory, The University of Newcastle, Callaghan, NSW 2308, Australia.
B Corresponding author. Email: natasha.czarny@studentmail.newcastle.edu.au
Reproduction, Fertility and Development 20(2) 295-302 https://doi.org/10.1071/RD07178
Submitted: 28 September 2007 Accepted: 11 November 2007 Published: 24 January 2008
Abstract
The spermatozoa of most marsupials lack nuclear stabilising disulfide-bonded protamines found in eutherian mammals. However, disulfide stabilisation has been observed in the acrosome of macropodid (Macropus eugenii) and phalangerid (Trichosurus vulpecula) marsupials. As a result this organelle, which is normally fragile in eutherian mammals, is robust and able to withstand physical and chemical challenge in these marsupials. The present study examined acrosomal characteristics of the spermatozoa of three dasyurid marsupials; the fat-tailed dunnart (Sminthopsis crassicaudata), eastern quoll (Dasyurus viverrinus) and northern quoll (Dasyurus hallucatus). In all species examined Bryan’s staining demonstrated that significant acrosomal loss occurred following physical challenge with osmotic stress, cryopreservation without cryoprotectant and exposure to detergent (Triton-X). Bromobimane staining indicated that the acrosomes of dasyurids lacked stabilising disulfide bonds. As reported for the wallaby and possum, calcium ionophore (A23187) did not induce the acrosome reaction-like exocytosis in dasyurid spermatozoa but treatment with diacylglycerol (DiC8) caused significant acrosome loss at concentrations similar to those effective for other marsupials. The present study found that the spermatozoa of dasyurids are more sensitive to physical challenge than the previously-studied marsupials and we suggest that this is due to the absence of acrosomal stabilising disulfide bonds.
Acknowledgements
We thank Australian Ecosystems Foundation, Remabi Park and Territory Wildlife Park for the supply of eastern and northern quolls. This research was supported by the University of Newcastle. Woolworths Ltd Jesmond store generously donated meat to feed the eastern quolls. NC was the recipient of a University of Newcastle Research Scholarship.
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