Maybe another Makybe?

‘Makybe Diva’ is a racehorse held dearly in the hearts of all Australians. ‘The Diva’ made racing history by being the only mare to win the Melbourne Cup three times and was the highest stakes-earner in Australasian horseracing history, with winnings totalling $14,526,685 [Wikipedia, 2007]. On November 1st 2005, ‘The Diva’ retired from racing.

The Diva winning her third Melbourne Cup

Image sourced from: [ABC Sport Online, 2005]

But, cloning could allow ‘The Diva’ to continue her success! Cloning is an emerging technology which enables these valuable equine genetics to be preserved.

‘Cloning’ is defined as the process of creating an identical copy of an original [Hinrichs, 2006]. It is important to realise cloned horses will not be identical to their donor, but will be a new individual, due to environmental and physiological factors [Hinrichs, 2005]. Already, 13 cloned horse foals have successfully been produced from adult donor cells [Hinrichs, 2006]. However, it remains very unproductive, with less than three percent success [Vanderwall, et al. 2006].

Equine cloning works by a method called ‘somatic cell nuclear transfer’. This process involves removing the nucleus from a somatic cell (a body cell other than a sperm or egg cell) of the horse which is to be cloned [Vanderwall et al, 2006]. This nucleus is then inserted into an enucleated egg (an egg with the nucleus removed) [Wikipedia, 2007]. The cell is then activated to divide by an electrical impulse. A blastocyst (an early stage embryo) is formed with almost identical DNA to the original organism [Answers.com]. The embryos are then surgically transferred to the oviduct of recipient mares, which have ovulated within 24 hours prior to the transfer [Vanderwall et al, 2006].

It sounds so simple…but why such low success?

The low success rate of cloning has been attributed to the high incidence of embryonic abnormalities, which result in abortion, still birth or compromised neonatal health [Vanderwall et al. 2006]. These complications are known collectively as ‘cloned offspring syndrome’ [Cross, 2001]. Reasons for these complications are still unclear.

Despite this, there still remains hope for Makybe’s genes. All pregnancy losses in horses have been found to occur mainly during the early gestation stage [Vanderwall et al. 2006]. Of the cloned foals born unassisted, a large majority have gone on to develop normally [Hinrichs, 2006].

In the not too distant future, a duplicate diva may be racing her way into our hearts!

‘The Diva’ with her three Melbourne Cup’s

Image source: [Annie, 2005]

Written by: Camille Percival
Student Number: 41024858

For some further information check out the following links:

• ABC Sport Online (2005). ‘Diva bows out after historic victory.’ Accessed May, 2007 at: http://www.abc.net.au/sport/content/200511/s1495356.htm
• Newspaper article with general information and race statistics on 'The Diva'

• Dulay, C. (2005). 'Cloning Thoroughbreds?' Accessed May, 2007 at: http://horseracing.about.com/od/latestnews/a/aa080105.htm
• A good website discussing advantages of cloning racehorses, and rules and regulations regarding the practice

• U.S. Department of Energy and the National Institutes of Health (2006). 'Cloning fact sheet.' Accessed May, 2007 at: http://www.ornl.gov/sci/techresources/Human_Genome/elsi/cloning.shtml
• A good website which explains cloning and answers common questions about how it works.

References:

1. ABC Sport Online (2005). 'Diva bows out after historic victory'. Accessed May, 2007 at: http://www.abc.net.au/sport/content/200511/s1495356.htm
2. Annie, W. (2005). 'An Aussie Legend.' Accessed May, 2007 at: http://abby1141-ivil.tripod.com/id42.html
3. Answers.com (2007). ‘Somatic cell nuclear transfer.’ Accessed May, 2007 at: http://www.answers.com/topic/somatic-cell-nuclear-transfer
4. Cross, J. (2001). Factors affecting the developmental potential of cloned mammalian embryos. Proceedings of the National Academy of Sciences of the United States of America (PNAS). 98: 5949-5951.
5. Hinrichs, K. (2005). Update on equine Intracytoplasmic sperm injection (ICSI) and cloning. Theriogenology. 64:535-541.
6. Hinrichs, K. (2006). Equine cloning. Veterinary Clinics: Equine Practice. 22: 857-866.
7. Vanderwall, D., Woods, G., Roser, J., Schlafer, D., Sellon, D., Tester, D. & White, K. (2006). Equine cloning: applications and outcomes. Reproduction, fertility and development. 18: 91-98.
8. Wikipedia. (2007). ‘Maykbe Diva.’ Accessed May, 2007 at: http://en.wikipedia.org/wiki/Makybe_Diva
9. Wikipedia. (2007). 'Somatic Cell Transfer.' Accessed May, 2007 at: http://en.wikipedia.org/wiki/Somatic_cell_nuclear_transfer