Analysis of a specific mutation in a gene in horses that affects the ability of horses to use alternate gaits is strongly related to racing performance and is advantageous for harness-racing horses. In domestic horses, the mutation has had a major impact on equine diversification, as the altered gait characteristics of a number of breeds apparently require this mutation, according to a study that includes a Texas A&M University researcher.
Gus Cothran, a professor in the Animal Genetic Lab of the College of Veterinary Medicine & Biomedical Sciences, is part of a team of researchers that examined motion in horses and also mice. Their findings are published in the current issue of Nature magazine.
Cothran and the team used a process called "whole genome SNP analysis" to study the genes of 70 Icelandic horses that had either four gaits or five, with the pace being the fifth gait. This pointed to a gene identified as DMRT3 that is critical for horse motion and limb movement.
They found that DMRT3 has a major impact on the movement of a horse, especially its gait. Horses have gaits classified in three descriptions of speed: walk, trot and gallop.
"'Gaitedness' is a trait that naturally occurs in all horses, but many breeds have been developed for a specific speed or gait," Cothran explains.
The team sequenced the DMRT3 gene of the test horses and found that in almost every case of gaited horses, there was mutation in the DMRT3 that caused a premature "stop codon" which causes the protein product of the gene to be terminated before the whole protein is completed. This alters the function of the protein, which leads to the differences associated with the gait.
Cothran and the team also examined the same gene and its effect on mice.
"We specifically looked at the gene and its effect on the movement of mice, such as its swimming ability," he explained."The motion ability of mice seemed suppressed and was similar, though not identical to that of gaited horses."
Cothran says with more research, the findings could have critical importance to horse breeding and horse racing. Many horses are specifically bred for certain types of gait, such as harness racing.
"We need to examine the DMRT3 on certain breeds and see if it can directly affect the speed and movement of horses," he adds. "We think it's an exciting step in looking at motion, speed and limb movement, and it's possible it could have implications in other species, too."
The project was funded by grants from the Swedish Brain Foundation and computer resources were supplied by the Royal Swedish Academy of Sciences Research.