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From: peb@SUN.COM (Paul Baclaski)
Newsgroups: sci.nanotech
Subject: DNA mutation elimination
Summary: DNA mutation elimination by checksum
Message-ID: <8904260543.AA26866@athos.rutgers.edu>
Date: 24 Apr 89 20:05:15 GMT
References: <8903230413.AA09060@athos.rutgers.edu> <8904180627.AA19469@athos.rutgers.edu>
Sender: nanotech@aramis.rutgers.edu
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How to eliminate mutations of DNA in a Human:

It seems to me that the main problem (omitted detail) with the DNA
repair design that Drexler proposes is: how can it know how to repair a
cell without carrying around a good copy of DNA with it?  The good copy
would be very large and restricts mobility.  Below is a description of a
technique that avoids this problem.

The target DNA is read and a "checksum" is computed.  Then, a
population of nanorobots is bred to know this particular checksum
(which can be made arbitrarily detailed to avoid the possiblity of
wrong-target).  The nanorobots are released into the bloodstream of the
target individual.  Then, instead of repairing cells, cells could
either be destroyed outright or they could be tagged for later, heavy
weight robots that move more slowly, but can carry more capability for
repair (and can zero in to the tagged cells with external equipment in
the loop).  A further level of detailed design would choose between
these methods based on the type of cell.

A larger, but less interesting from the space-time trade off
perspective is avoiding the immune system, but that is a problem for
immunologists...


Paul E. Baclaski
Sun Microsystems
peb@sun.com

[I suspect the only mutations worth this much trouble to catch are
 cancers.  One might well be able to catch them with a set of heuristic 
 matching patterns, and not have to read the whole dna at all. 
 On the other hand, if you are trying to live for- absolutely -ever...
 --JoSH]