X-Message-Number: 7755
Date: Tue, 25 Feb 1997 15:21:07 -0800 (PST)
From: Joseph Strout <>
Subject: More on cloning

> Message #7747
> From: "Perry E. Metzger" <>
> The technology is not yet available. Presuming the Scottish sheep
> cloning experiment is real (probable, but the experiment hasn't been
> reproduced yet -- we have only one sheep)

The San Diego Union-Tribune reported that it's been repeated seven times.

> If in five years the technology is mature enough (a big if given all
> the hypotheticals) and if there are cryonics organizations with
> cloning only patients (a possible hypothetical -- I honestly don't
> know), then the cryonics organizations with such patients should
> quietly seek professionals and surrogates to perform the procedures,
> preferably out of the country and with all involved having signed
> confidentiality agreements.

Has anyone actually specified in their contract that they should be cloned
when such is possible?  I still fail to see the point of that...

> Message #7748
> From: 

> If the cloned sheep lives a normal life span then DNA damage or limited 
> cell division can not be the cause of aging. Goodbye Hayflick.

No, DNA damage still can be (and probably is) the cause of aging.  So can
limited cell division, or telomeres, or anything else.  They've simply
taken a differentiated mammary cell, and convinced it that it's a
pluripotential fertilized egg cell.  This says nothing about the cause of
aging that is not already said by the existince of normal reproduction.

Suppose it's DNA damage, as I suspect.  This is gradual and cumulative.
Probably most of the cells they try to clone fail, and DNA damage is a
likely significant factor in the failure.  You're automatically selecting
for the one cell here and there which is not damaged in significant ways.

Suppose it's telomeres (a probable reason for the Hayflick limit?).  Maybe
they convinced the cell to produce telomerase, in enough quantities to
fully rebuild the cell.

For that matter, this is not so different from cancer.  Cancer cells are
also born of adult, differentiated cells, yet they evade the Hayflick
limit and somehow overcome DNA damage (or in fact, thrive on it).

Great stuff, but really doesn't say much about aging as far as I can see.

-- Joe

|    Joseph J. Strout           Department of Neuroscience, UCSD   |
|               http://www-acs.ucsd.edu/~jstrout/  |

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