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From: dd@beta.UUCP
Newsgroups: sci.med,sci.bio
Subject: Re: Dating age of humans
Message-ID: <9516@beta.UUCP>
Date: Mon, 31-Aug-87 01:29:11 EDT
Article-I.D.: beta.9516
Posted: Mon Aug 31 01:29:11 1987
Date-Received: Tue, 1-Sep-87 01:07:56 EDT
References: <26333@sun.uucp> <1960@kitty.UUCP> <3836@cit-vax.Caltech.Edu>
Organization: Los Alamos Natl Lab, Los Alamos, N.M.
Lines: 13
Keywords: Ageing Human Carbon
Xref: utgpu sci.med:2722 sci.bio:569
Summary: Turnover times; DNA not permanent

In article <3836@cit-vax.Caltech.Edu>, palmer@tybalt.caltech.edu (David Palmer) writes:
> Since neurons do not reproduce (much) after birth, the DNA does not
> change (does it?) so the same carbon atoms remain in the DNA as at birth.

Nope.  DNA is repaired even if the neuron does not divide.  Thus the turn-
over time, while long (I don't know the exact number, but I'd bet it's well
under a year) is finite.  If I remember correctly, the only compounds which
are not turned over are the collagen-containing tendons and ligaments.  I
suspect the latest version of Principles of Biochemistry (White et al.) will
have the details.

dan davison/theoretical biology/t-10 ms k710/Los Alamos National Lab/Los
Alamos, NM 87545.  "I'm a doctor, not an elevator" Dr. McCoy