Re: [isml] Re: Differences between clones baffles science

From: Michael M. Butler (
Date: Sun Jan 02 2000 - 08:50:12 MST

> Harvey Newstrom wrote:
> > This is not as much as a "Duh!" as you think. It is was currently believed
> > that DNA defines an animal's appearance and much of its personality. These
> > clones had identical DNA and different egg cells. The egg cells were
> > thought to be empty containers to hold the DNA. Now that the animals look
> > and act different, it appears that DNA is not the end-all blueprint that we
> > thought it was. Apparently, much of the animals definition comes from
> > non-DNA sources.

One should always be able to revisit hypotheses.

There are several things that I, far from an expert in this field, can
think of that don't require "non-DNA sources" (or more precisely, non-NA

1) Mitochondrial DNA. This has been handwaved about before. I had my
doubts long ago that one should call an organism a true clone if it
didn't have identical mitochondrial DNA. Not unlike calling Y2K the
Millennium, we appear to be stuck with the misnomer. I propose calling
what we have today "loose cloning", and getting *all* the genetic
material as right as possible, "tight cloning".

2) Increased mutation rate due to yet-undetermined factors in the
current procedures. There is nothing that says the DNA sampled is
error-free and 100% representative of the animal it was taken from.

3) Differences in expression of existing genes due to methylation and
other only-recently-discovered factors. See #2 above.

4) Retroviruses present in the ova.

5) Then there's the telomere-shortening problem. I can imagine different
clones aging at different rates.


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