Domestic horse genome sequenced

Washington, Nov 6 : The genome of a domestic horse has been successfully sequenced by an international team of researchers.

According to scientists, findings have important implications for improved breeding of horses and for studies of human health.

"This very high-quality genome sequence of the horse is important because it gives us access to specific sequence information that we can now apply to identify the genes for specific traits in the horse," said co-author Cecilia Penedo of University of California, Davis.

Penedo contributed to the genome sequencing effort by supplying DNA from Arabian horses and quarter horses and by working on a horse linkage map, which identified genetic markers for various traits across the horse chromosomes.

In reporting the horse genome sequence, the researchers noted that there are more than 90 hereditary conditions that affect both humans and horses.

Because horses share these conditions, which include infertility, inflammatory diseases and muscle disorders, the horse is an important model for improving the understanding of human diseases.

The sequencing project revealed that the horse genome is somewhat larger than the dog genome and smaller than the human and cow genomes.

In comparing the horse and human chromosomes, the researchers discovered that 17 out of 32 -- or 53 percent of -- horse chromosome pairs are composed of material from a single human chromosome, while only 29 percent of dog chromosomes are composed of material from a single human chromosome.

This indicates that fewer chromosome rearrangements separate humans from horses than separate humans from dogs.

The researchers were also surprised to find on horse chromosome 11 the existence of an evolutionarily new centromere.

Centromeres are key structural features of chromosomes that are necessary for the movement of chromosomes when cells divide, a function that ensures normal distribution of all genetic material to each daughter cell.

The functional but evolutionarily immature centromere in the horse may provide a model to study factors responsible for how centromeres function.

Penedo noted that the completion of the high-quality horse genome sequence has provided researchers around the world with ready access to specific gene sequences that can be applied to mapping various traits of the horse.

The study has been reported in the Nov. 6 issue of the journal Science.

--ANI