Handling the horse genome

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The Nov. 5 issue of Science reports that researchers have successfully sequenced the genome of a grey research horse named Twilight, and they say it sheds light on the domestication process and shows significant similarities to other sequenced placental mammals, like the bovine. Claire Wade, along with colleagues from around the world, report the first high-quality draft sequence of the Equus caballus genome, and they say one of the key findings is a region that appears to be in the process of forming a brand new centromere, the central region of a chromosome that plays a major role in cell division, on equine chromosome 11. The authors note that about 53 percent of horse genes appear on chromosomes in the same order as found on human chromosomes—a phenomenon known as conserved synteny between species—and they might serve as models for human disorders in the future. (The genome has already enabled genetic tests to be developed for some equine genetic disorders such as Polysaccharide Storage Myopathy, Hereditary Equine Regional Dermal Asthenia, and Hyperkalemic Periodic Paralysis.) However, despite the large degree of conserved synteny between humans and horses, the seemingly new centromere on chromosome 11 is not found in any other species, which suggests that it is evolutionarily new. The authors say this centromere is functional and stable, but too new to have acquired the typical marks of other mammalian centromeres. The horse genome also indicates that horses were originally domesticated from a relatively large number of females, but very few males.

Article #22: "Genome Sequence, Comparative Analysis, and Population Genetics of the Domestic Horse," by C.M. Wade at Broad Institute in Cambridge, MA; Massachusetts General Hospital in Boston, MA; University of Sydney in Sydney, NSW, Australia and colleagues. Please see article for the complete list of authors and affiliations.