Re: mitochondrial DNA

["Tim Gwinn" <***>]

Hi Judith,

In my search tonite, I only found one paper online where they compared the
efficacy of using maternal donor cells versus "foreign" donor cells (which
would presumably have different mitochondrial DNA than from a maternal cell)
in cloning of cows. The paper notes that: "Consequences of constructing
clones in a ”foreign” egg cytoplasm remain unclear but may contribute to the
inefficiency of the cloning procedures for producing live, healthy
offspring."
The conclusion was: "Use of maternal egg cytoplasm for constructing cloned
embryos did not improve developmental competence of clones to establish or
maintain a pregnancy to term."
I cannot tell what year the paper was written (at least 1998+). It is a
short paper, from the Univ. of Tennessee, located at:
http://animalscience.ag.utk.edu/pdf/Reports/Edwards_LE%20departmental%20repo
rt%20maternal%20cytoplasm%202002.pdf


I also found the following item which states that sperm do have mitochondria
(they apparently do need them to produce energy) but these sperm
mitochondria may be chemically tagged for destruction once inside an egg:
http://www.findarticles.com/cf_dls/m1200/1_157/59021040/p1/article.jhtml


It would seem to make sense that mismatches of nuclear and mitochondrial DNA
ought to promote problems, diseases and death among such clones. But, if
this does not bear out, then perhaps the two are not that tightly coupled.
That might offer some evidence that is suggestive of the notion that the
mitochondrial components of cells were seperate organisms(?) at one point in
time, and at some later evolutionary time became endosymbiotes, and retain
some degree of independence of internal structures from its symbiotic
partner. As a symbiote, perhaps as long as the mitochondria serve their
functional role for the whole cell, variations in their internal structure
can be tolerated.

Regards,
Tim


> -----Original Message-----
> From: ROSEN Forum [mailto:*** Behalf Of Judith
> Rosen
> Sent: Monday, December 15, 2003 9:34 PM
> To: ***
> Subject: Re: mitochondrial DNA
>
>
> Off and on over the years, I've done a bit of research into mitochondrial
> DNA, because I was fascinated with the notion that not all of our "genetic
> blueprint" is contained in the nuclear DNA. I also found it
> interesting that
> all mitochondrial DNA is inherited through the mother (because
> the egg cell
> is large enough to contain mitochondria but the sperm cell is not). This
> doesn't get talked about very much, and I don't understand why that is. It
> seems to me that if certain inherited human metabolic diseases are being
> studied, for example, then they ought to be looking into mitochondrial
> DNA... but it has never gotten a single mention in any of the studies I've
> seen.
>
> With regards to Jeff's experiment idea, I think the mitochondria
> must play a
> large role in the genetic make up of any offspring resulting from an egg
> where the mitochondria are not from the same mother as the nucleus. Does
> anyone know of studies where this aspect of cloning is discussed? It seems
> to me that the premature aging that we've seen in cloned animals
> may be due
> to a mismatch in genetic proteins within cells or some other side-effect
> from this situation.
>
> Judith
>
> ----- Original Message -----
> From: "Jeff Pridaux" <***>
> To: <***>
> Sent: Monday, December 15, 2003 1:37 PM
> Subject: Re: [ROSEN] SciAm Dec. 2003 - DNA, Epigenetics, and Complexity
>
>
> > The following experiment might be interesting:
> >
> > As I understand it, for animals cloned so far, the DNA from a viable egg
> > cell is replaced with DNA from another cell (from the same
> animal) in such
> > a way to "trick" the egg to think it was fertilized.  It may be that the
> > whole nucleus is swapped out of the egg.  Then the animal (or a like
> > animal) carries the fertilized egg to term resulting in a clone of the
> > animal (who donated the DNA)
> >
> > An interesting alternative would be to have the donor egg and the
> replacing
> > DNA being from different animals.  And somehow just swap out the DNA
> > without swapping out the surrounding chemicals around the DNA in the
> > nucleus.  If that were possible and if an animal resulted that wasn't
> > exactly the same as the DNA donor, then that would demonstrate that the
> DNA
> > isn't EVERYTHING.
> >
> > I suspect, though, that this experiment may be very difficult (or maybe
> > impossible) to perform.
> >
> >
> >
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