From: Jeff Davis (jrd1415@yahoo.com)
Date: Sat Dec 07 2002 - 17:41:57 MST
--- "Robert J. Bradbury" <bradbury@aeiveos.com> wrote:
>
> And in some cases it has, e.g. Deinococcus
> radiodurans. I believe that
> D. radiodurans can repair up to 300 double strand
> breaks, most probably
> through homologous recombination repair pathways (my
> speculation).
Now, of course, most of us have heard of:
Super Survivor Deinococcus radiodurans
http://www.ornl.gov/hgmis/publicat/microbial/image3.html
But the above web piece is a real eye opener. (The
very first web site on the list when I googled D.
radiodurans.) It gives a bit more detail than I've
seen up till now, suggests that the genome has been
mapped, and generally gets one jazzed about the
possibilities.
I loved the graph comparing the radiation
survivability of humans, cockroaches, E. coli, and D.
radiodurans. At .5 kGy (whatever that means) of
radiation, humans, roaches, and E. coli are dead. D.
radiodurans doesn't even begin to notice until 6 kGy.
And then, check out this little note from the caption
of the graph:
"When older colonies of D. radiodurans are used, their
survival extends much farther, to around 17kGy (1.7
million rads)."
First, "Wow!" Then, "What's that all about?!!" Their
normal tolerance is upwards of twelve times that of
'regular' creatures, but in a pinch they can crank
that up by a factor of three to ~34 times the
resistance of 'regular' creatures.
And what role does the 'tetrad' structure play in
this? Might it somehow provide a fourfold redundancy
in informational, ie DNA, backup? Some sort of
bacterial "I'll show you mine if you show me yours"
kind of thing. Bacteria have long been known to share
DNA in a 'fast and loose' fashion not typically (as
far as I have heard) associated with eucaryotic cells.
What a sweet little bug this is, with mysteries and
treasures galore!
Best, Jeff Davis
"Everything's hard till you know how to do it."
Ray Charles
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