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View Full Version : Double-strand DNA break repair at -15 C



A.DIM
2013-Oct-13, 01:36 AM
More evidence showing how life adapts to the most extreme environments is published HERE.

From the Abstract: " ... Our results provide direct evidence for the repair of DNA lesions, extending the range of complex biochemical reactions known to occur in bacteria at frozen temperatures. Provided that sufficient energy and nutrient sources are available, a functional DNA repair mechanism would allow cells to maintain genome integrity and augment microbial survival in icy terrestrial or extraterrestrial environments."

And here's what The Daily Galaxy has to say about it (http://www.dailygalaxy.com/my_weblog/2013/10/subsurface-microbes-frozen-millions-of-years-may-exist-on-mars-dna-repair-mechanism-make-it-possible.html): “This isn’t a random process,” Christner said. “This tells us that the cells are repairing their DNA. This is important because we don’t typically think of these as being conditions under which complex biological processes are going on.”

Christner said that these findings make it reasonable to speculate that if life ever evolved on Mars and microbes are still frozen somewhere in the subsurface, those microbes might still be viable if given the right conditions.

“It just keeps looking better for conditions of habitability on Mars,” Christner said. “This is relevant in an astrobiological sense because if these DNA repair mechanisms operate in Earth’s cryosphere, extraterrestrial microbes might be using this survival mechanism to persist on other icy worlds in the solar system. We are very excited about these results.”


No doubt!
I can't help but wonder though, should we be surprised? Life's hardiness continues to astound us, and has for long, to where "zones" or "conditions" for habitability have been sufficiently blurred. For me it's simpler to think life is a cosmic phenomenon and adapts to the countless environments within this universe. Planets, moons, comets, solar systems, galaxies, etc. are not closed systems in my view, as if islands isolated within their own bubbles. No, these "islands," as it were, are in my mind open systems with plenty material washing ashore and falling from the sky. Life, it seems, will find a way.

Selfsim
2013-Oct-13, 04:33 AM
... Christner said that these findings make it reasonable to speculate that if life ever evolved on Mars and microbes are still frozen somewhere in the subsurface, those microbes might still be viable if given the right conditions. “It just keeps looking better for conditions of habitability on Mars,” Christner said... So what does it mean if no such microbes are found 'in the right conditions', somewhere below the subsurface of Mars'?

Is it then not reasonable to speculate that this finding means exactly 'zip' when it comes to Mars?


“This is relevant in an astrobiological sense because if these DNA repair mechanisms operate in Earth’s cryosphere, extraterrestrial microbes might be using this survival mechanism to persist on other icy worlds in the solar system. We are very excited about these results.”... And what does it mean if these mechanisms and microbes are not found on other icy worlds in the Solar System?
Is that then also relevant in an Astrobiological sense?

A.DIM
2013-Oct-13, 03:37 PM
.. So what does it mean if no such microbes are found 'in the right conditions', somewhere below the subsurface of Mars'?

Is it then not reasonable to speculate that this finding means exactly 'zip' when it comes to Mars?

So...
You're presupposing a null result to affirm "reasonable" speculation that this science, the findings reported, would mean "zip?"
And you want me to disagree?
Nope.


... And what does it mean if these mechanisms and microbes are not found on other icy worlds in the Solar System?
Is that then also relevant in an Astrobiological sense?

I'd say if we sufficiently explored our solar system and find no such things, then we might justifiably say we've discovered some limits of life. This would be astrobiologically significant. As it is, everything we've learned, and are learning, suggests that life is far more resilient than we tend to assume.

Selfsim
2013-Oct-14, 08:06 AM
So...
You're presupposing a null result to affirm "reasonable" speculation that this science, the findings reported, would mean "zip?"
And you want me to disagree?
Nope. All I'm asking is for you to consider the other side of the coin, (ie: the negative case), which as far as I can see, has equal speculative import as the affirmative case does. And now, it seems you've confirmed an unwillingness to do that, (which is Ok by me .. just recognise that this is an artifact of pursuing evidence which can support only one particular hypothesis ... that's all).


I'd say if we sufficiently explored our solar system and find no such things, then we might justifiably say we've discovered some limits of life. This would be astrobiologically significant. ... and 'sufficiently explored' is quantified, how?

As it is, everything we've learned, and are learning, suggests that life is far more resilient than we tend to assume.Well it might appear to be resilient within the environment it evolved in, (which may be somewhat of a surprise for some), but just how much of that resilience is attributed to its evolving and adapting along with that particular environment?

Did it do that on the surface of Mars?

A.DIM
2013-Oct-14, 01:52 PM
All I'm asking is for you to consider the other side of the coin, (ie: the negative case), which as far as I can see, has equal speculative import as the affirmative case does. And now, it seems you've confirmed an unwillingness to do that, (which is Ok by me .. just recognise that this is an artifact of pursuing evidence which can support only one particular hypothesis ... that's all).

I think if you read closely you’ll see I acknowledged the flip side. You put forth a what-if scenario on which to base your reasonable speculation that these findings would, in retrospect, mean zip when it comes to Mars. And I don’t disagree. However, I don’t necessarily agree both sides are of equal speculative import.
The null hypothesis “Life can’t survive this that here there… etc” has been repeatedly disproven. It would seem then that “life adapts to this that here there …etc” is the safer bet, and of more speculative import.


... and 'sufficiently explored' is quantified, how?

Good question. Presently I’d say no less than 5 locales need be investigated.


Well it might appear to be resilient within the environment it evolved in, (which may be somewhat of a surprise for some), but just how much of that resilience is attributed to its evolving and adapting along with that particular environment?
Did it do that on the surface of Mars?

Maybe, maybe not. This is why we need a little less sniffing around in the atmosphere and looking in / under rocks; we must send another life detection package to Mars!
As I said earlier, I think life adapts to countless environments in its universe. These “islands” or niches, if you will, no doubt range from the micro to the macro, from hostile to conducive. More and more we have evidence to believe life could exist on Mars, has filled that niche; double break repair in DNA at these temps adds to that evidence.

R.A.F.
2013-Oct-16, 02:31 PM
...I’d say no less than 5 locales need be investigated.

Could you please list those locales for us?...or would that be "off topic"?

R.A.F.
2013-Oct-26, 02:14 PM
Could you please list those locales for us?...or would that be "off topic"?

Since I am interested in a conversation, not a monologue, and since there has been no response from A.DIM for the last 10 days, I am withdrawing this question...

Selfsim
2013-Oct-26, 09:43 PM
Not that it matters at all how I would answer the seemingly odd proposal of only 5 'locales, but I sort of guessed them to be along the lines of the traditional: Mars, Europa, Titan, Enceladus, Venus(?) ... (Y'know ... planet-wide environments that themselves, contain an almost infinite set of micro-environments .. so as to just provide enough leeway to accomodate uncertainties and provide sufficient contingency for supporting the rather odd original statement ...)

Maybe we could have a guessing competition as to what A.Dim meant?

(On second thoughts: "nah" ... :) )

A.DIM
2013-Oct-29, 01:44 AM
Since I am interested in a conversation, not a monologue, and since there has been no response from A.DIM for the last 10 days, I am withdrawing this question...

Why not start a thread if you’re really interested in a conversation? A discussion about potentially inhabited locales in our system is only tangentially on topic here.

“Withdrawing this question” seems an odd declaration.

A.DIM
2013-Oct-29, 01:45 AM
Not that it matters at all how I would answer the seemingly odd proposal of only 5 'locales, but I sort of guessed them to be along the lines of the traditional: Mars, Europa, Titan, Enceladus, Venus(?) ... (Y'know ... planet-wide environments that themselves, contain an almost infinite set of micro-environments .. so as to just provide enough leeway to accomodate uncertainties and provide sufficient contingency for supporting the rather odd original statement ...)

Maybe we could have a guessing competition as to what A.Dim meant?

(On second thoughts: "nah" ... :) )

You win, Selfsim, even before second thoughts!

Although, I didn’t suggest “only 5 locales” … I said no less than; That was a rather odd twist of my answer to your query.

Selfsim
2013-Oct-29, 02:02 AM
You win, Selfsim, even before second thoughts!

Although, I didn’t suggest “only 5 locales” … I said no less than; That was a rather odd twist of my answer to your query.Ok, A.DIM … I was just kidding around … :)

What would be your 'no less than 5 locales'? … (I'm curious).

Cheers

R.A.F.
2013-Oct-29, 01:05 PM
“Withdrawing this question” seems an odd declaration.

What can I say...I got tired of waiting for a response....

A.DIM
2013-Oct-29, 02:12 PM
Ok, A.DIM … I was just kidding around … :)

What would be your 'no less than 5 locales'? … (I'm curious).

Well, you already listed the usual suspects in the guessing game you didn't have (good guesses!), but I could add Luna, comets, asteroids and perhaps other moons to that list. We are after all, wanting to quantify "sufficiently explored," remember? That is the "rather odd original statement" what lead to your non competition of listing potentially inhabitable locales.

Cheers!