Czarny N A, Mate K E, Rodger J C
Marsupial Research Laboratory, The University of Newcastle, Callaghan, NSW 2308, Australia.
Reprod Fertil Dev. 2008;20(2):295-302. doi: 10.1071/rd07178.
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.
大多数有袋类动物的精子缺乏在真兽类哺乳动物中发现的具有核稳定作用的二硫键结合鱼精蛋白。然而，在大袋鼠科（尤金袋鼠）和袋貂科（帚尾袋貂）有袋类动物的顶体中观察到了二硫键稳定作用。因此，这个在真兽类哺乳动物中通常很脆弱的细胞器，在这些有袋类动物中却很坚固，能够承受物理和化学挑战。本研究检测了三种袋鼬科有袋类动物精子的顶体特征；肥尾 Dunnart（粗尾袋鼬）、东部袋鼬和北部袋鼬。在所检测的所有物种中，布莱恩染色表明，在受到渗透应激的物理挑战、无冷冻保护剂的冷冻保存以及接触去污剂（曲拉通-X）后，顶体出现了显著损失。溴化双马来酰胺染色表明，袋鼬科动物的顶体缺乏稳定的二硫键。正如对沙袋鼠和负鼠的报道，钙离子载体（A23187）不会诱导袋鼬科动物精子发生类似顶体反应的胞吐作用，但用二酰基甘油（DiC8）处理会在与对其他有袋类动物有效的浓度相似的情况下导致显著的顶体损失。本研究发现，袋鼬科动物的精子比之前研究的有袋类动物对物理挑战更敏感，我们认为这是由于顶体缺乏稳定的二硫键所致。
