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RE: Single and double strand DNA breaks

Many anthropologists feel that natural radiation was the energy the drove
evolution.  It answers the questions posed by the geneticists as to why
there are deviations to the standard formulas of genetic probabilities.


Carl A. Brenner
Health Physicist
Battelle Memorial Institute
Columbus, OH

> -----Original Message-----
> From:	Andrew Karam [SMTP:karam.1@osu.edu]
> Sent:	Friday, April 03, 1998 8:29 AM
> To:	Multiple recipients of list
> Subject:	Single and double strand DNA breaks
> Dear RADSAFERs -
> One topic about which I am curious is that repair of double-strand DNA
> breaks is so much more "iffy" than repair of single-strand breaks.  I
> realize that SSBs are inherently easier to repair than are DSBs, but I am
> wondering if there might be any additional factors.
> For instance, it occurred to me that, until lungs and gills evolved (well
> into the history of life) life would only have been exposed to
> alpha-emitting atoms that happened to be within about a micron of the cell
> (or algal mat or whatever).  This was the state of things for the first 3
> billion years life existed.  After the evolution of gills and lungs, of
> course, animals could pump large volumes of water or air past tender
> internal tissues, increasing alpha exposure.  Could it be that alpha
> radiation is so damaging simply because life didn't have to worry about
> DSBs until relatively recently?
> This is all speculation, of course; I would welcome any comments from
> those
> of you who know more about this than I.
> Sincerely,
> Andy
> The opinions expressed above are well-reasoned and insightful.  Needless
> to
> say, they are not those of my employer. (with apologies to Michael
> Feldman)		
> Andrew Karam, MS, CHP					(614) 292-1284
> (phone)
> The Ohio State University 					(614)
> 292-7002 (fax)
> Office of Radiation Safety					"The mind is
> not a vessel to
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> but a fire to be
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> (Plutarch)	   
> (karam.1@osu.edu)