peb@SUN.COM (Paul Baclaski) (04/25/89)
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]
brucec@demiurge.UUCP (Bruce Cohen) (05/02/89)
In article <8904260543.AA26866@athos.rutgers.edu> peb@SUN.COM (Paul Baclaski) writes: >How to eliminate mutations of DNA in a Human: ... ... Discussion of using nanbots with a DNA checksum to catch mutations ... > ... 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). ... While this sounds like it would work in principle, there's considerably more to it than this for two reasons: 1) There is more than 1 chromosome per human cell. I think you would have to keep a separate checksum for each chromosome. And germ cells (sperm and ova) would have to be treated specially, as would developing fetuses for that matter ... 2) The genetic material for the symbiotic cell organelles like mitochondria is not in the cell nucleus along with the chromosomes. The variety of genetic material to deal with makes the pattern recognition problem much harder. Wouldn't want to blast a cell because a nanobot spotted a strand of DNA for a mitochondrian and mistook it for a malformed gene. On the other hand, I believe there are occasional malfunctions in the transmission of organelle DNA. Bruce Cohen brucec@orca.wv.tek.com Interactive Technologies Division, Tektronix, Inc. M/S 61-028, P.O. Box 1000, Wilsonville, OR 97070