Link between Gene, Physical Endurance


This article has been taken from Working Dog Web-Heritage North Press


Proven In Research by British Scientists

If you have ever advocated breeding Siberians specifically for working and racing traits -- but lacked hard evidence to support your argument -- you’ll be glad to know your chances of winning those arguments just improved dramatically. You can now demolish anyone's argument that Siberian Huskies, just by being purebred Siberians, will be great athletic sled dogs.

This May, British scientists published a paper in the May 21 edition of the influential journal, Nature, making a clear link between a specific gene and both muscular strength and endurance at high altitudes. The gene was found in human males. While similar work would have to be conducted in canines to be conclusive, parallels are likely.

The genetic pattern found by Dr. Hugh Montgomery, an intensive-care physician and lecturer in cardiovascular genetics at University College in London, is so vivid that it makes a clear case for the importance of breeding for working qualities such as endurance.

ACE Gene a Key in Endurance, Strength

Montgomery and fellow researchers at the Centre for Cardiovascular Genetics found two different varieties or alleles of the gene that directs the production of an enzyme known as ACE -- for "angiotensin-converting enzyme." Researchers have found that ACE is involved in blood pressure regulation and may influence the development of skeletal muscle. They also found that ACE appears to boost the intake of oxygen and nutrients to muscle cells. 

These two different varieties are known as I and D. Because our genes come in pairs -- one from each parent -- people can have three patterns for this gene -- II, DD or ID. In other words, we can have a pair of I alleles, a pair of D alleles, or one of each. What are the differences?

The British scientists looked at two groups of men. While the exercise the men were doing differed, the outcomes showed similarities.

Athletic Ability Tied to Patterns of Gene Alleles

One group included 78 "raw army recruits" who were put through an identical physical training program over a 10-week period. The men with the II pattern or the ID pattern showed improvements in repetitive weight training at a rate 11 times that of men with the DD pattern.

The second group included 33 British mountain climbers, with special attention focused on 15 men who had successfully climbed above 6,000 meters or 26,000 feet -- without oxygen. Among the group of 15, six carried the II pattern while nine carried the ID pattern. None carried the DD pattern for this gene.

"... a minor variation in the gene...results in quite significant performance differences...."

``What we found was a minor variation in the gene that results in quite significant performance differences,'' said Dr. Hugh Montgomery. 

In addition to the benefits during exercise, Montgomery sees benefits for victims of heart attach and stroke. He believes that the benefit "is in saving lives. If this gene does work by making cells more efficient, it might be able to stop cell death when fuel supply is reduced. 

Implications for Breeding Canine Athletes

To give a simple scenario for what this discovery means for breeding canine athletes -- if in fact dogs have a comparable mechanism -- consider these options:

-- breeders work their sled dogs intensively and identify the individual dogs that never seem overly tired at the end of a hard run. The breeders then determine to breed only those animals -- both sire and dam -- with such high endurance. The likelihood would be that the dogs are either II or ID for this gene. In turn, the pups would either be all II [if both parents were II] or approximately half would be II and half ID [if one parent were II, the other ID]. All would show the above average endurance.

-- breeders either work their Siberians lightly or not at all, and thus have no yardstick on endurance. Or, even when they know the relative endurance of each dog, they choose to breed for other traits. The likelihood in these scenarios will be that some of the dogs used for breeding would carry the DD pattern. Over several generations of breeding this way, more and more of the offspring would turn out to be DD, or less enduring.

This is just one gene, albeit an apparently quite influential one. One can easily see how, over time, a gene pool could contain an increasing percentage of the alleles for more or less athletic performance capability, depending on a breeder’s selection decisions. 

If the old adage "breeding best to best" seemed to you somehow unconvincing when arguing for the importance of breeding for athletic traits, you now have a better argument, and this is it: there exist two forms of the gene for the enzyme known as ACE, with the I form directly linked to greater physical endurance and muscle strength, the D form to lesser abilities. Breeding choices clearly influence athletic performance.

-- Barbara Petura, Editor, WorkingDogWeb

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