The term Ògene jockeysÓ originally referred to molecular biologists. Now it has taken on a new meaning in an international collaboration to map the genome of the horse.
The Horse Genome Project, launched in 1995, is off and running. ÒIn just a few years, we have made enormous progress in gene mapping in horses, and that progress continues at a terrific rate,Ó says Doug Antczak, director of the James A. Baker Institute for Animal Health at Cornell's College of Veterinary Medicine, who works on the project.
Although the mapping of human genes is way ahead of comparable efforts in horses, a stunning discovery in Sweden two years ago gave the Horse Genome Project a boost: Whereas patterns of gene order on human Ð and primate Ð chromosomes tend to be very different from those of most other species, the patterns between humans and horses are very close.
ÒIn other words, there is a very strong conservation of gene order on the chromosomes between the two species,Ó explains Antczak, the Dorothy Havemeyer McConville Professor of Equine Medicine at Cornell. ÒThat means that much of the progress that has been made in mapping human genes can be Ð and is being Ð applied to horses. This is a huge boon for equine researchers, saving millions of dollars in time and energy and allowing equine research to forge ahead at an unprecedented rate.Ó
Gene mapping is the decoding of the thousands of genes that line up on the 32 pairs of rod-shaped chromosomes within the nucleus of each equine body cell. The genes determine all the traits and characteristics that are passed down from parents to offspring, such as coat color, running ability, conformation (structure), courage or genetic defects.
By having a good comparative map between humans and horses, researchers now know, for example, that many of the genes located on human chromosome 6 are on horse chromosome 20. By knowing which genes on which chromosome are linked to muscular or immune diseases in humans, equine researchers can go directly to the corresponding chromosome in horses to look for the disease-causing gene in question.
CornellÕs focus, supported primarily by the Zweig Memorial Fund, has been to pinpoint particular regions on a chromosome that carry genes for particular traits, such as running speed or disease susceptibility.
In just a few years of gene mapping, researchers have been able to use their new information to develop genetic tests to prevent stallion-mare pairings that would result in inherited diseases in the offspring. Soon, scientists hope to be able to select the genes for such traits as conformation, fertility and performance, and in doing so to avoid genetic defects.