Giant panda (Ailuropoda melanoleuca) spermatozoon decondensation in vitro is not compromised by cryopreservation
Rebecca E. Spindler A C D , Huang Yan B , JoGayle Howard A , Wang PengYan B , Zhang Hemin B , Zhang Guiquan B and David E. Wildt AA Conservation and Research Center, Smithsonian’s National Zoological Park, 1500 Remount Road, Front Royal, VA 22630, USA.
B China Conservation and Research Center for the Giant Panda, Wolong, China.
C Present address: Reproductive Programs, Toronto Zoo, 361A Old Finch Avenue, Scarborough, ON M1B 5K7, Canada.
D Corresponding author. Email: spindler@uoguelph.ca
Reproduction, Fertility and Development 18(7) 767-775 https://doi.org/10.1071/RD06030
Submitted: 5 April 2006 Accepted: 21 May 2006 Published: 28 August 2006
Abstract
Natural breeding of giant pandas in captivity is compromised, making artificial insemination and spermatozoa cryopreservation essential for genetic management. This study examined the influence of freeze–thawing on traditional parameters such as motility and spermatozoon functionality, specifically decondensation in vitro. Giant panda spermatozoa were assessed before and after rapid cryopreservation (4°C to –130°C over 2 min) in liquid nitrogen vapour. Spermatozoa pre-incubated in medium for 6 h were co-incubated with cat zonae (2 zonae μL–1) for 30 min to effect capacitation and an acrosome reaction. Spermatozoa were then mixed with mature cat oocyte cytoplasm (2 cytoplasm μL–1) for 4 h and evaluated for decondensation. Frozen spermatozoa were less motile (P < 0.05) than fresh counterparts immediately post-thawing, but not after 6 h incubation. There were more (P < 0.05) spermatozoa with completely diffused chromatin post-thaw (10.4 ± 1.3%; mean ± s.e.m.) compared to fresh counterparts (5.1 ± 1.0%). However, there was no overall difference (P > 0.05) in the incidence of decondensation between fresh (4 h, 69.8 ± 5.9%) and thawed (4 h, 71.5 ± 4.9%) spermatozoa after exposure to cat oocyte cytoplasm. It is concluded that the ‘rapid’ method now used to cryopreserve giant panda spermatozoa has little impact on spermatozoon decondensation.
Acknowledgments
We thank Lena May Bush, Jonathan Aaltonen and Abby Matthewson for technical assistance and Dr Budhan Pukazhenthi for valuable advice. The China Wildlife Conservation Association is a cooperative partner in the Smithsonian’s National Zoological Park’s research and conservation program for the giant panda. This research was generously funded by Friends of the National Zoo, Morris Animal Foundation and a financial gift from Missy and Clinton Kelly.
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