Brent Meeker writes:
> Russell Standish wrote:
> > The NS article is
> >
> > issue 2556 of New Scientist magazine, 19 June 2006, page 50
> >
> > the actual published work is
> >
> > Cell, vol 122, p 133
> >
> > What he measured was the age of carbon in DNA, which is only a tiny
> > fraction of the total number of atoms making up a cell. So I guess you
> > are right in your more restricted meaning of "same".
> >
> > Cheers
>
> I wonder what part of neuron remains over a long period time. I can well understand
> the electrolytes and other components that are part of the metabolic cycle turning
> over fairly quickly. But what about the structural protiens that give shape to the
> axons? What about the myline sheath? Do they really turn over quickly too?
All cellular components are continuously being repaired and replaced, including structural
ones. I am not sure of the actual figures for individual components in human brains but
probably protein turnover has a haf-life of days. For example, experiments with radiolabeled
tyrosine suggest that half the protein in a mouse brain turns over every ten days:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1164796
Jesse Mazer quoted a study a while ago suggesting that turnover of synaptic structures
was even more rapid, a matter of minutes, but I cannot find the reference.
Stathis Papaioannou
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Received on Sun Oct 08 2006 - 00:31:46 PDT