AW: [ RadSafe ] Bacterium can survive doses of ionising radiationthousands of times stronger than would kill a human

[John Jacobus]

Rainer,
Thank you for the pointing of the article by Dr.
Michael Daly about the suspected role of Mn in the
survivability of Deinococcus radiodurans.  Of course,
that has nothing to do with the LNT.  Nevertheless, I
am sure that you felt the need to interject this
irrelevant comment.  The doses we are discussing are
significantly beyond those associated with low level
radiation dose, and the organism is not a eukaryotic.
As I mentioned there are many basis life forms that
are able to withstand high doses or radiation, heat,
toxic chemicals, etc.  

Yet, another mechancism that protects the DNA of
cells, from bacteria to humans, are heat shock
proteins. 
http://en.wikipedia.org/wiki/Heat_shock_protein
It is possible that D. radiodurans may possess as yet
unidentified HSPs.

--- Rainer.Facius at dlr.de wrote:

> From WIKIPEDIA: "Michael Daly of the Uniformed
> Services University of the Health Sciences suggests
> that the bacterium uses manganese to protect itself
> against radiation damage."
> 
> John, 
> 
> thank you for this additional pointer. In the
> meantime Daly et al (2007) corroborated the above
> conjecture by showing that Mn protects the repair
> enzymes(!) from being degraded by high doses.
> 
> <quote>We present the case that protein, rather than
> DNA, is the principal target of the biological
> action of IR in sensitive bacteria, and extreme
> resistance in Mn-accumulating bacteria is based on
> protein protection. <endquote>
> 
> 
> Once more you see the by now common place finding
> that - contrary to still most text-books and to the
> credo of LNT proponents - not the primary DNA damage
> determines the fate of the irradiated organism but
> the sophistications of its repair systems. Therefore
> I also thank Fred Dawson for his pointer which led
> me to the PLoS article.
> 
> Kind regards, Rainer 
> 
> 
> Daly MJ, Gaidamakova EK, Matrosova VY, Vasilenko A,
> Zhai M, et al. Protein oxidation implicated as the
> primary determinant of bacterial radioresistance.
> PLoS Biol 5#4 (2007)e92.
> 
> Dr. Rainer Facius
> German Aerospace Center
> Institute of Aerospace Medicine
> Linder Hoehe
> 51147 Koeln
> GERMANY
> Voice: +49 2203 601 3147 or 3150
> FAX:   +49 2203 61970
> 
>  
> 
> 
> ________________________________
> 
> Von: radsafe-bounces at radlab.nl im Auftrag von John
> Jacobus
> Gesendet: Fr 13.04.2007 18:59
> An: Dawson, Fred Mr; radsafe at radlab.nl;
> srp-uk at yahoogroups.com
> Betreff: Re: [ RadSafe ] Bacterium can survive doses
> of ionising radiationthousands of times stronger
> than would kill a human
> 
> 
> 
> Fred,
> I would look at
> http://en.wikipedia.org/wiki/Deinococcus_radiodurans
> 

+++++++++++++++++++
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-- John F. Kennedy 

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com

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