Re: RC: Re: Breeding theories

[CMKSAGEHIL@aol.com]

Truman Prevatt wrote:

<< I understand that an older mare may not be a good as growing
 > the fetus as a younger one, but what physics explains the aging of the
 > genes? >>

In normal day-to-day life, chromosomes wad up into a kind of protected tangle 
where they are relatively safe from external insults from chemicals, free 
radicals, and other similar sorts of things that can cause damage to the DNA. 
 During division they unwind from this coiled wad and pair up.  In this 
state, they are extremely vulnerable to damage.  In regular cell division, 
they replicate and divide, forming new nuclei, and then wad back up in their 
"protected" state fairly quickly.  In the formation of haploid cells (eggs 
and spern), they pair up and then just separate without replicating so that 
you only have one chromosome from each pair.  That halved number of 
chromosomes then sits in this unwound vulnerable state for the entire 
reproductive live of the female mammal, since this all occurs before she is 
born.  The damage to the genetic material is random but significant.  There 
is also a certain amount of damage that seems to occur to all of them with 
aging.  The result is that the older mare (or woman, or any mammalian 
species) may have some ova that are relatively normal, some that have only 
small points of damage that will be adequately "covered" by a normal gene on 
the corresponding sperm cell (depends on what genes are damaged whether this 
will work), some that will produce a viable but abnormal offspring, and some 
that are so badly damaged or damaged in such important spots that the embryo 
will not develop past a certain point.  The older the female, the more of 
these occur.  Liken it to a sniper that sits on a water tower for several 
years and with some degree of regularity looses rounds into a small town.  
Furthermore, everything in the town is static--you can't repair the damage or 
replace dead people.  Sometimes he might hit people, and might even kill one. 
 Sometimes he might shoot a tiny hole in an attic window that really isn't 
very important or knock a chip off the corner of a cinderblock building, and 
sometimes he might hit nothing at all.  There is always the chance that the 
very first round will kill someone, which would be like the young female 
having a problem with a non-viable egg or a resultant abnormal offspring.  
Odds are low, but it can happen  But over time, the important damage will 
begin to mount up and the odds increase that you will encounter an individual 
ovum with significant genetic damage.  In the case of the female, this 
process begins to accelerate with age, as enzymes, etc. that are a byproduct 
of aging also begin to circulate.

Hope that helps.

Heidi


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