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 _________________________________________________________________ Be one of the first to try Windows Live Mail. http://ideas.live.com/programpage.aspx?versionId=5d21c51a-b161-4314-9b0e-4911fb2b2e6d --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~----------~----~----~----~------~----~------~--~---
