In article <393A5866.30BAA342 at mindspring.com>, Iuval Clejan
<clejan at mindspring.com> wrote:
> Aubrey de Grey wrote:
> >
> > > Is there less mtDNA damage in post-ovulatory eggs than in other cells
> > > in the same organism?
> >
> > I don't know of any study of this. Getting enough such eggs to measure
> > mtDNA mutations is probably difficult.
> >
>> I guess one should do this with mice. By "other cells" I now mean
> pre-ovulatory oocytes.
>
There is some clinical work on human oocyte health and age in relation to
oocyte mitodchondrial function. If you're interested E mail me - I've got
a couple of reviews coming out shortly. Basically the stringent genetic
bottleneck that egg mitochondria go through in early embryogenesis is
*supposed* to maximise homoplasmy and perhaps limit Muller's ratchet for
mtDNA but the evidence so far is indirect. While apoptosis in
spermatogenesis is known to eliminate sperm with DNA breakage and meiotic
errors, no one as yet has been able to demonstrate such a selective filter
for oocytes, whether one is talking about nuclear or mitochondrial DNA.
However, there are some intriguing possibilities including "testing" for
OXPHOS capacity during the exponential phase of late oogenesis and
follicular recruitment.
Liu, L. and Keefe, D.L. (2000) Cytoplasm Mediates Both Development and
Oxidation-Induced Apoptotic Cell Death in Mouse Zygotes. Biol. Reprod.,
62, 1828-1834.
Liu, L., Trimarchi, J.R. and Keefe, D.L. (1999) Thiol oxidation-induced
embryonic cell death in mice is prevented by the antioxidant
dithiothreitol. Biol. Reprod., 61, 1162-1169.
Liu, L., Trimarchi, J.R. and Keefe, D.L. (2000) Involvement of
Mitochondria in Oxidative Stress-Induced Cell Death in Mouse Zygotes.
Biol. Reprod., 62, 1745-1753.
Rinaudo, P., Niven-Fairchild, T., Buradagunta, S. et al. (1999)
Microinjection of mitochondria into zygotes creates a model for studying
the inheritance of mitochondrial DNA during preimplantation development.
Fertil. Steril., 71, 912-918.
--
Jim Cummins
Murdoch University
<cummins at central.murdoch.edu.au>
