Clear Implications for Breeding Racing Sled
Link between Gene, Physical Endurance
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 --
youll 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
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
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
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
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
-- 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 breeders 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,
Read the BBC News Online article at the following URL: http://news.bbc.co.uk/low/english/sci/tech/newsid_97000/97590.stm
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