Re: RC: DNA testing update

[CMKSAGEHIL@aol.com]

In a message dated 2/8/00 4:57:26 PM Pacific Standard Time, woa@stormnet.com 
writes:

<< I'll let you know if Boyd has any information to add about the DNA
 marker research, which it appears has been abandoned. Too bad; it would
 have been nice to differentiate between"ringers" and purebreds. >>

Thanks, Bette--that was a pretty good summation.  I would comment on the 
above, though (NOT a flame, NOT an insult) as it is not so much that research 
has been "abandoned" but rather that it simply does not apply to the question 
that breeders wished to have answered, which was to have some way to tell 
breeds apart by DNA.  The following was sent to me by geneticist Michael 
Bowling (and shared with his permission) in response to earlier discussions 
of this subject, and is in part a quote on the subject with a few notes and 
some emphasis from him:

<<Actual quote (From the current Journal of Heredity):

"[H]ighly polymorphic microsatellites [the technique that was to be
employed in that business Bette refers to] are likely one of a few
molecular marker types that have sufficient information to resolve
diagnosis among _recently_diverged_ populations such as the global
radiation of Drosophila melanogaster, which is estimated to have occurred
within the last _10,000-15,000_ years [italics mine]."

The current estimate is that the horse was domesticated 5-6000 years ago,
and the oldest breed records we have go back to about 300 years ago. Horse
breeds are not "diverged populations" in the terms of this technique.>>

In other words, breeds simply are not sufficiently dissimilar genetically for 
us to be able to tell them apart by available DNA techniques.

Heidi