World -First Sequencing of the Horse Genome

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2nd March 2010

Article taken from Roundhouse - Newsletter of the Veterinary Science Foundation of University of Sydney - Dec 09

 

The horse was only supposed to have a partial assembly of its genome.  But genome sequencing has developed so quickly and cost-effectively that a first complete sequence of the horse genome has now been published in the prestigious Science journal.  Roundhouse spoke with the leading author of the project, Professor Claire Wade.

 

A leading equine specialist in the Faculty, Professor Wade has led an international team of scientists from more than ten countries to produce the first complete genetic sequence of the horse. 

Sequencing the genome of the Equus caballus (the domestic horse which was represented by a Thoroughbred) is likely to increase our understanding of horse biology and horse-related genetic diseases.  It will also provide important models for human disorders with horses having over 90 hereditary conditions, many of which are also shared by humans. 

"There are important medical reasons for sequencing the horse genome.  We can now provide better tests for athletic performance as well as respiratory and allergic disorders like asthma and skin allergies which may have relevance to human medicine," said Professor Wade. 

A key research finding was the discovery of a newly formed centromere, the part of the chromosome that the spindle attaches to during cell division.  In the horse genome it has not had time to develop the characteristics of a normal mammalian centromere.  This finding promises to give some insight into the poorly understood biology of centromere formation.

 "It's kind of rare to see evolution in action in that way.  It gave us a novel insight into mammal genomic biology," said Professor Wade.

The project also made use of cutting edge sequencing technology to make mutation discoveries.  "We knew from our dog research that a lot of mutations are not in the coding region of the genes so we used the new technology to help us look in the non-coding regions," said Professor Wade.

The sequencing of the horse genome shows exciting prospects not only for further mutation discoveries but also for a wide variety of other horse related projects. 

"It's exciting to be involved in these types of projects.  We've enabled a new metabolic disorder to be mapped and we can also do new genetic testing that in the future will help us prevent certain diseases.  The process has also allowed us to learn more about muscle- biology which can benefit both horses and humans, and we've recently been able to map behavioural traits in horses.  The new genome sequence has allowed all of this to happen." 

The project also uncovered a finding which disputes the commonly held belief that the Mongolian wild horse (Przewalski's horse) is presumed to be the ancestor of the modern  domestic horse. 

"Our analysis showed there had been some mixing up between modern horses and the Mongolian horse, so really it was no different to any other domestic horse.  They're not really deserving of their own species status," said Professor Wade.  "You could easily presume that all the wild horses that ever existed were taken up by humans and used for domestic purposes." 

"Many people have a problem with this idea but the main reason humans caught wild horses was because they were tasty.  They weren't as dangerous as coyotes or bears so I think initially people just rounded them up to eat them."