Major Criticisms of The Telomeric Theory
james at nospam.com
Sat Sep 12 00:04:47 EST 1998
> Budding yeast (S. cerevisea), are an exception to this in that they go
> through assymetric mitotic division. The mother cell of the yeast then age
> much in the same manner as most other eukaryote cells. Austriaco NR Jr, at
> The Massachusetts Institute of Technology has demonstrated how the telomeres
> in the mother cell regulate the silencing machinery of the genes to control
> aging in these cells.
I don't know that I've read the stuff by Austriaco (what's the paper title?), but
I would like to point out that this statement you make as fact is far from
accepted by everyone. In fact, I would hope that Austriaco doesn't really put it
the way you did because we have no idea what aging *is* in yeast, so we can't
possibly know what is controlling it. In fact, some people would speculate that
it is a physical phenomenon, or at least partially physical (as oppsed to
genetic) so the whole idea of "genes to control aging" is inapplicable.
Yes, there is some correlation between age and loss of silencing at certain loci
(rDNA or mtDNA, I forget which at the moment), but we are far from knowing what
> Some multi-cellular organisms have developed a very effective way to maintain
> telomeric length without utilizing telomerase. The adult cells of the worm
> (C. Elegans), and the fly (Drosophila melanogaster), and many other similar
> organisms avoid telomeric shortening by not dividing at all.
Just a note here: All organisms (with linear chromosomes) maintain at least
their gamete telomeres somehow. Drosophila don't have telomerase, but they do
use homologous recombination to add repetetive sequences.
> Cells cannot survive without maintaining telomeric length but they can't
> survive without cell walls either so this may not relate to aging.
Tom - I can't believe you said that! Are you feeling OK??? Seriously though,
this is just the king of critical thinking that many people would benefit from,
and I applaud you making a very valid analogy here.
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