From: CurtAdams@aol.com
Date: Sat Nov 20 1999 - 15:20:17 MST
In a message dated 11/19/99 10:29:35 PM Pacific Standard Time, jr@shasta.com
writes:
> Thank you for the information. Apparently, modifying the genes of mice can
> extend their life span. If identical modification happened as a result of
> mutation rather than engineering, would the mutant individual have a
biological
> advantage?
Yes, provided there were no disadvantages. If the effect were small it could
still be
lost through drift (bad luck) but 30% is a lot, even late in life.
>Could such a mutation occur naturally in millions of years of mice
generations? --J. R.
There are billions of mice in the world, and each one carries
a few dozen point mutations from the previous generation. So
any 1-base mutation is happening several times a year. Since
this is a loss of function, dozens of mutations (loss of the start
codon, any splicing goof, most additional stop codons, a couple
of significant base changes, and deactivation of the promoter)
would produce the phenotype.
Of some relevance is work John Tower did on increasing antioxidant
activity in flies. Some lines got better, some got worse, and
some had no change. This kind of mutant won't necessarily have a
big advantage. On the other hand, you wouldn't want to take a
drug for this effect without screening - what if you're one of the
lines that loses?
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