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RESEARCH ARTICLE

Swim-up of tammar wallaby (Macropus eugenii) spermatozoa in Biggers, Whitter and Whittingham (BWW) medium: maximisation of sperm motility, minimisation of impairment of sperm metabolism and induction of sperm hyperactivation

Minjie Lin A B , Xiyi Zhang A , Ray N. Murdoch A and R. John Aitken A
+ Author Affiliations
- Author Affiliations

A Discipline of Biological Sciences, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia.

B Corresponding author. Email: minjie.lin@newcastle.edu.au

Reproduction, Fertility and Development 29(2) 345-356 https://doi.org/10.1071/RD15152
Submitted: 15 April 2015  Accepted: 13 July 2015   Published: 27 August 2015

Abstract

A variety of media were compared for their ability to sustain the motility of tammar wallaby spermatozoa over an 8-h period following swim–up from coagulated semen. The study demonstrated that a modified Tyrode’s solution, Biggers, Whitter and Whittingham medium (BWW) was significantly better than any of the other assessed media in supporting wallaby sperm motility. After 8 h of incubation in BWW, motility was maintained at 79.3 ± 9.3%, with 77.0 ± 10.4% rapid and 65.7 ± 8.7% progressively motile spermatozoa. By contrast, motility was <10% at the same 8-h time point in all of the other media assessed. After 2 h of incubation in BWW, tammar spermatozoa consumed more oxygen than their counterparts in PBS (52.0 ± 2.7 vs 75.0 ± 6.6 μL per 108 spermatozoa per 2 h; P < 0.001). Motility was not enhanced in any of these media by the addition of 5 mM N-acetyl-D-glucosamine, the major energy substrate in wallaby semen. However, addition of dibutyryl cAMP and pentoxifylline in BWW resulted in the extremely rapid induction of hyperactivated motility in the entire sperm population. This burst of hyperactivated motility was entirely dependent on calcium in BWW and significantly inhibited by calmidazolium, a calmodulin inhibitor. A set of computer-assisted sperm analysis parameters were identified that permitted the accurate quantification of hyperactivation rates in this species. This is the first comparative analysis of media for harvesting and incubating marsupial spermatozoa and the first record of hyperactivated motility in any marsupial species.

Additional keywords: cAMP, marsupial spermatozoa, N-acetyl-D-glucosamine, sperm capacitation.


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