Jurassic park lecture

Anthonie Muller awjm at holyrood.ed.ac.uk
Tue Mar 11 10:07:23 EST 1997


On 4 Mar 1997, Ed Rybicki wrote:

> > From:          Anthonie Muller <awjm at holyrood.ed.ac.uk>
> > When I read all this talk about DNA conservation in amber, I must always
> > think about H.J.Dombrowski, who  claimed to have isolated bacteria from
> > old salt deposits (see for instance Umschau 23 (1965) 736-736). It seems
> > to me that a high salt concentration may very well protect against all
> > kind of degrading effects.
> > Why is his work ignored? Have I missed an obvious counterargument?
> 
> Strikes me as a lot of paradigms are getting overturned in the field
> of amplification of ancient DNA / reviving bacteria from ages
> past...Svante Paabo went on a crusade a while back against REALLY
> ancient DNA with the same arguments used in a previous post to this
> group; trouble is, people kept amplifying it despite the fact that 
> natural oxidative / degradative processes were supposed to have nuked 
> it beyond recognition after only a couple of thousand years!!!  New 
> Scientist has just run an article on brine shrimp which can survive 
> for years in a totally lifeless (as in: not metabolising ANYTHING) 
> state; why then should bacteria not be able to be dehydrated out of 
> sight, and still recover viability?  Even after a couple of million 
> years, if conditions are favourable?  While life may not be more 
> resilinet than we CAN imagine, it is probably more hardy than we DO 
> imagine.  Someone ought to repeat the salt work; sounds like a good 
> seam to mine (sorry)!
>                      Ed Rybicki, PhD  
>       Dept Microbiology     |   ed at molbiol.uct.ac.za   
>    University of Cape Town  | rybicki at uctvms.uct.ac.za


I had forgotten that I have read some other papers on this subject; in
fact I referred to these papers in a paper of mine!
According to the Science Citation Index these are the only recent
references to Dombrowski:

C.F. Norton
Archeal halophiles (halobacteria) from two British salt mines.
J. Gen. Microbiol. 139 (1993) 1077-1081

H Stan-Lotter
Comparison of membrane ATPases from extreme halophiles isolated from
ancient salt deposits.
Origins of Life Evol Biosph 23 (1993) 53-64

M J Kennedy
Preservation records of micro-organisms: evidence of the tenacity of life
Microbiology 140 (1994) 2513-2529

The question remains: why does one wants to consider that DNA is
conserved in amber, but not its conservation in salt? Or are bacteria not
interesting enough? 
If oxidation causes instability, anaerobic conditions might protect.

I can imagine that radioactivity (C14) of DNA constituent atoms may
destabilize a genome, but nevertheless self-repair mechanisms do exist.

Determination of the amount of radioactive isotopes in a bacterium by
massaspectroscopy might by the way be a method to proof an old age. 

In Scientific American of a few months (?) ago there was  an article about
bacteria deep underground, in natural water. The bacteria were
supposed to have been there since geological times, and the bacteria were 
supposed to be not very active. If their metabolic activity is very low,
the instability of their DNA should also be a problem. So, again, why
discriminate against salt bacteria?

Ton Muller
The Thermosynthesis Home Page
http://www.ed.ac.uk/~awjm





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