Re: Mars meteorites contain scars similar to bacterial etching.


"Aidan Karley" <doIlookDAFTenoughTOpost@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
wrote in message
news:VA.00000d7c.009ac179@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
In article <dvvvc8$l8j$1@xxxxxxxxxxxxxxxxxxxxxx>, Pete wrote:
In this case, though, I guess they can be excused on
the basis of the highly unlikely but not impossible theory that
earth life was seeded from Martian meteorites.
It's similarly credible that life on Mars might have been seeded
from life on Earth, in which case looking for DNA is not unreasonable.
(The transfer of impact ejecta from Earth to MArs is considerably less
likely, but not impossible. In fact, a week or two ago someone was
publishing modelling results that a small but non-zero proportion of
the ejecta from a large impact on Earth could make it out as far as
Titan.)

Still, I would have
hoped they would have more imagination.

You have a candidate genetic/ physiological system that's not
DNA based, and you've got the catalogue numbers for dyes that will make
the important parts of this system stick out like the proverbial sore
thumb under the microscope?
We do at least *know* that DNA/ peptides can do the job, and the
reagents for showing these components are well-known. So this test is
eminently do-able. (It's actually quite well known - here I am a humble
rock jock, but I know who I'd ask about how to do it, if I had an
interesting meteorite to work with. She's quite a looker too, which
doesn't hurt. Follow the link to the "team" from
http://www.microscopy-uk.org.uk/index.html?http://www.microscopy-uk.org
uk/nanobes/nanointro.html ) Whereas you've got pretty much any
chemistry you want to play with trying to stain up any other *possible*
life chemistry - we can't even be certain that it's impossible to have
a silicon-based biochemistry.

Imagination is important. But designing doable experiments is
important too. Absence of staining from reagents for DNA indicates the
absence of undegraded DNA ; it precisely does not indicate absence of
life. Similarly, the detection of DNA would indicate the presence of
DNA, but doesn't rule out that it might be environmental contamination.

--
Aidan Karley, FGS
Aberdeen, Scotland,
Location: 57°10'11" N, 02°08'43" W (sub-tropical Aberdeen), 0.021233

Aberdeen seems to be a good place to study geology.

Guess you have seen this info on Carbonaceous Chondrites before.
Murchison in particular has a lot of amino acids- they're different from
whats in DNA though..

<http://www.meteoritestudies.com/protected_ORGANICS.HTM>

David Weir has one of the best sites on meteorites

www.meteoritestudies.com




.

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