Dear Matthias,
Your questions are very pertinent. I'll try to reply the best I can,
by trying to avoid confusion between "diversity" and "complexity".
Let's try to simplify.
Here is my modest understanding of the issue, bearing in mind I am by
no means an expert in biology and its development, neither I am
regarding the conditions in space that can provoke (or at least had
provoked in Murchison) a high molecular diversity.
Our spectra richness gives (experimental) evidence of intrinsic and
compositional diversity in space, within and across chemical classes,
which is an acknowledged feature of extraterrestrial chemistry (see
e.g. J. R. Cronin et al., Geochim. Cosmochim. Acta 57 (1993), 4745
Comparable but lesser diversity was also found in terrestrial organic
matter. Ref.: N. Hertkorn et al., Anal. Chem. 80 (2008), 9808 ;
Norbert Hertkorn, co-author of our paper, is expert, along with Phil
Schmitt-Kopplin, of NOM's (Natural Organic Matter, thus "humic acids"
& related, present in terrestrial aqueous systems ....)
To answer more specifically your 6 questions (that are related), I'd say:
No, the development of life does not depend (necessarily) on a kind of
reduction of chemical diversity.
In other words, life can develop (as it did on Earth) from a
relatively small (reduced or not) number of initial molecules,
provided some other parameters (than in space) act as driving force
(presence of oxygen, water (under ambient conditions), ambient (= not
extreme) temperature.....).
But this does not imply that it can't develop from a large number of
molecules as well.
This does certainly not mean that such a life did not develop
"somewhere in space" under different conditions.
As mentioned J. R. Beda in his comments on our paper in "C&EN" (Feb 16, 2010):
"The challenge now is to fish out molecules that may have some
important early biochemical role".
Would life be linked to a process of picking up elements out of the
construction kit and combine them ?
I defy anyone to answer that question.
Now regarding distinction between diversity and complexity, I don't
imagine that the complexity of terrestrial biochemical "space" is
necessarily a result of reduction of (initial) diversity.
I believe this can also most probably occur if a high diversity is maintained.
In other words, should the high diversity of molecules (such as we
found in Murchison) be also present on Earth at the time when the
conditions were conductive to the expansion of life, this expansion
would probably have occurred as readily as if that diversity was
somewhat restricted (this is an hypothesis that I'd be glad if someone
more expert than me could comment - but not necessarily confirm).
To conclude, we give in our paper a little more detailed picture than
what is summarized in one sentence of the abstract.
The DIVERSITY of extraterrestrial organics was driven (but also
possibly sometimes restricted) by "extreme" physical parameters such
as "temperature", radiation, various alterations....leading to a
selectivity of reaction pathways (entropy-driven continuous
distribution of molecular compositions and structural characteristics
of ABIOTIC syntheses).
Such thermodynamic and kinetic constraints might deviate from
terrestrial biogeochemistry, under our current mild conditions
(oxygen, ambient temperature etc).
In other words, these latter conditions could lead, from a restricted
number of initial molecules (but not necessarily restricted!) to a
high and EARTH-SPECIFIC COMPLEXITY, by inducing various favorable
transformations.
Just some thoughts from a non expert chemist. I encourage Phil
Schmitt-Kopplin, who is reading us, to possibly add his own comments.
I also stay flexible to any (constructive or destructive) remark from
any of you.
Matthias, I will forward you the full paper as attachment.
Unfortunately, for the list, I have no link to provide. Those
interested, feel fee to request a copy.
Kind regards to all,
Zelimir
Oh, I almost forgot:
YES, definitely Murchison smells (a quite strong smell, not really
unpleasent, especially when the sample was sealed in some jar for
years).
Matthias Bärmann <majbaerm...@web.de> a écrit :
Hello Zelimir & Murchisionados,
highly interesting indeed: thanks so much for informing us about
your and your colleagues scientific work and giving us so the
feeling of being privileged enough to sit in the very first row.
If I understand your approach correct, your non-targeted focus of
investigation leads directly to a highly diverse pattern.
The last sentence of the abstract reads: "This molecular complexity,
which provides hints on heteroatoms chronological assembly, suggests
that the extraterrestrial chemodiversity is high compared to
terrestrial relevant biological- and biogeochemical-driven chemical
space." The high level of extraterrestrial chemodiversity vs. the
less diverse terrestrial "chemical space" - could that mean that
development of life could depend on a kind of reduction of
diversity? Caused by selection (= "targetting"?)? Life would be
essentially linked to a process of picking up elements out of the
construction kit? But than it begins to play by combining them?
Wouldn't that point to the necessity to make a strong distinction
between diversity and complexity? Could that mean that the
complexity of terrestrial biological and biochemical "space" is a
result of reduction of (initial) diversity?
Perhaps six (crazy) questions too much from a non-natural scientist ...
Best regards,
Matthias B.
----- Original Message ----- From: <zelimir.gabel...@uha.fr>
To: <meteorite-list@meteoritecentral.com>
Sent: Tuesday, February 16, 2010 9:58 PM
Subject: [meteorite-list] organics in Muchison.....
Darren, list,
The media info Darren is speaking about refers to the research we (a
group of scientists) are being conducting since several months on
Murchison, namely a non targeted analysis of its extraterrestrial
organic contents.
In a post I sent by end of last September, I had notified the list of
that work by just mentioning the keywords "Murchison" and "organic
contant".
The paper, that was submitted for publication in due time (right in
time for the 40th anniversary of Murchison fall), was just anounced
released out of press a couple of hours ago.
Here is the reference: PNAS, 107 (7), 2763 -2768 (2010).
Abstract can be read here:
http://www.pnas.org/content/107/7/2763
More discussions are available through various media press comments
(easily found by Googling with keys: "Murchison, Phillippe
Schmitt-Kopplin").
May I just insist that the incredible number of molecules we had found
originated from the fact that the screening was not targeted.
Also we never claimed that any of the hundreds of thousands of
molecules we detected had a pre-biotic origin, something that seems to
provoke debate in the media.
Our work just shows there's no shortage of molecules on meteorites in
general, and in Murchison, taken as reference in particular, that
origin-of-life researchers could investigate...
Those familtar with Ensisheim shows might remember that Philippe
(Phil) was our new enthroned Ensisheim meteorite guardian in 2008.
Phil is the head of the lab in Neuherberg (Munich) where all the
measurements (combined FTICR-MS,NMR & GC) were run.
We all, co-authors, are deeply indebted to him for his discern and
faith in initiating that challenging research and for his expertise
that caused its success beyond any of our initial expectations.
So far we have recorded tons of other data on "many more" other
meteorites. More exciting and weird results are coming continuously;
thay will be published in the months to come.
My best wishes,
Zelimir
Shawn Alan <photoph...@yahoo.com> a écrit :
Darren and List
Thank you for the read up on Murchison meteorite on how scientist
have identified over 14,000 compounds and counting. While we are on
the topic of Murchison meteorite, I came across an article on line
that points out these interesting facts and finds on the Murchison
as quoted from the article as follows....
"Presolar grains are the oldest materials in the solar system,"
says Philipp Heck of the University of Chicago.
"The ages of the grains clearly indicate that they are older than
the solar system."
But just how old?
Heck and his colleagues isolated 22 grains from the Murchison
meteorite, which is well-known for the
organic material it contains, and measured how long the grains
spent in interstellar space before winding up
in our nascent solar system. The implied grain ages, reported in a
recent paper of the Astrophysical Journal,
appear to support a hypothesis that our solar system formed after a
smaller satellite galaxy crashed into the
Milky Way around 6 billion years ago."......
"From the isotope abundances, the researchers estimate that the
majority of grains spent between 3
and 200 million years in interstellar space before falling into our
molecular cloud some 4.6 billion
years ago."
Here is the link to the article I found on line.
http://www.astrobio.net/pdffiles/news_3202.pdf
and if your up for a read, here is an article on the age of
presolar SiC grains found in Murchison meteorite.
http://presolar.wustl.edu/ref/Gyngard09b.pdf
Enjoy
Shawn Alan
[meteorite-list] Murchison-- chock full o' stuffDarren Garrison
cynapse at charter.net
Tue Feb 16 00:25:30 EST 2010
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http://news.discovery.com/space/meteorite-crammed-with-millions-of-organic-compounds.html
Meteorite Crammed with 'Millions' of Organic Compounds
By Ian O'Neill | Mon Feb 15, 2010 04:52 PM ET
A meteorite that hit the town of Murchison, Australia, hasn't quit
giving up its
secrets.
The Murchison meteorite is one of the most studied space rocks because many
pieces were recovered after it was seen breaking up as it fell through the
atmosphere in 1969. Approximately 100 kg of the carbonaceous chondrite was
recovered.
Carbonaceous chondrites are extremely important to scientists as they were
formed from material that existed in the solar system's
planet-forming disk of
gas and dust. They are, quite literally, time capsules holding onto
a 4 billion
year old record of the birth of our solar system.
In this case, the Murchison meteorite has given us another clue as to the
abundance of organic chemicals that existed before the Earth had formed. In
fact, this particular meteorite may have originated from material
older than our
sun.
"We are really excited. When I first studied it and saw the
complexity I was so
amazed," said Dr Phillipe Schmitt-Kopplin, of the Institute for Ecological
Chemistry in Neuherberg, Germany.
"Meteorites are like some kind of fossil. When you try to
understand them you
are looking back in time."
This new research made use of high resolution spectroscopic tools
to identify
the various compounds inside. Although this meteorite has provided
scientists
with vast amounts of information about specific carbon-based
organics before,
this was the first non-targeted study. In other words, the
researchers weren't
tracking down just one type of chemical, they did a broad analysis
for all the
chemicals it might contain.
And what they found came as a shock, it appears that the primordial
solar system
probably had a higher chemical diversity than present-day Earth.
In this study, 14,000 specific compounds including 70 amino acids were
identified. But this number appears to be the tip of the iceberg;
the meteorite
probably contains millions of different organic compounds. More detailed
analysis will now be carried out.
But why is this important? To understand the diversity of organic
chemicals that
were floating around a primordial solar system will help us
understand how life
may have appeared on Earth. This particular chunk of carbonaceous chondrite
drifted through the gas and dust of the early solar system,
collecting all the
basic organic chemistry from around that time, does that mean
diverse organic
chemistry is the "norm" for proto-planetary star systems?
These organic compounds are known to exist on comets, asteroids and other
planetary bodies, so what makes Earth the hothouse of life when
everywhere else
seems to be lifeless?
If organic chemistry is ubiquitous, perhaps planning to "seed" young star
systems with Earth-based life isn't such a good idea. The
conditions for life
may not be that rare after all.
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