Comments on: Extremophilia

By: D.radio

D.radio — Thu, 11 May 2006 09:59:01 +0000

Anybody knows what time need Deinococcus for have their mitosis? and what type of grow table it have?
I’m a student of Biotechnology and I needed for a work.

By: Deinococcus

Deinococcus — Tue, 21 Feb 2006 05:12:30 +0000

The debate about ALH84001 continues, but scientific consensus after a decade does not support the original paper published by McKay. That said, the decision by Science to publish the report was good since it forced the community to think carefully about the topic of biosignatures and what to look for in the future. Unfortunately, a Mars sample return mission seems very far away.

By: Plato

Plato — Fri, 17 Feb 2006 05:38:03 +0000

Probability 1, by Amir D. Aczel, page 99,

In 1994 Allan Hills 84001 was handed over to David Mckay of Nasa's Johnson Space Center. Mckay asembled a nine-memebr team including scientists at NASA, Stanford University, the Universty of Georgia, and McGill University in Montreal. The team endeavored to determine whether there were any signs of life on the meteorite

Well?

By: Deinococcus

Deinococcus — Fri, 17 Feb 2006 00:31:30 +0000

For the latest on Deinococcus, see http://www.usuhs.mil/pat/deinococcus/index_20.htm.

Stay tuned for astrobiology-relevant work on radiation-driven microbial ecosystems and how manganese protects proteins, not DNA, during irradiation. Curious about what all of you are being taught on why ionizing radiation kills cells.

Mike

By: Dumb Biologist

Dumb Biologist — Fri, 27 Jan 2006 04:12:32 +0000

P. aeroginosa can even grow in distilled water, but if it was sterilized water, it isn't aseptic any longer if something is growing in it. Anway, the reason it can grow in distilled water is because even that has some traces of shmutz in it that microbes with very simple nutritional needs can thrive in (sort of). Actually, I think most examples of the genus Pseudomonas (maybe I should use "pseudomonads") do well in a huge range of conditions, and they're not picky eaters at all.

By: Paul Orwin

Paul Orwin — Fri, 27 Jan 2006 03:57:53 +0000

Something I didn’t expect to see at CV! Some loose use of the word “sterile” over here. I think you mean “sterilized”. Lots of things get sterilized, very few things are sterile (in the sense of abiotic). Bacteria are remarkably good at being where they ought not to be (by our standards). BTW, Deinococcus was recently found in the human stomach (a pretty extreme place as wellk, but apparently not as bad as we thought).

By: Dumb Biologist

Dumb Biologist — Fri, 27 Jan 2006 01:57:23 +0000

I don’t know that much about D. rad. molecular biology, but there’s repair, and then there’s repair+complete genomic redundancy at all times. When bacteria suffer a lot of DNA damage (as I’m sure D. rad. does in extreme environments), they typically resort to something called an “SOS response”. Repairing double-strand lesions requires replication of DNA, but when damage piles up too quickly for careful error-correction, the SOS response allows for quick-and-dirty replication that sacrifices accuracy for efficiency. If bacteria constantly have to SOS, the mutations will pile up to lethal proportions.

I’m guessling D. rad. can just say “Screw that, I got a handy, carefully synthesized extra copy right here. And a few more where that came from.”

That’s a pretty good trick, to be able to carry around multiple extra genomes for repair whenever you need it, and cope with it all the while. Look at what happens to us when we get even one extra chromosome.

By: Philip Downey

Philip Downey — Thu, 26 Jan 2006 20:32:30 +0000

I didn’t like that APOD very much, because they made the ability to repair DNA sound very exotic. Except for viruses, every organism can repair its DNA. Bacteria, us, and everything in between, can all do it.

Uncle Al: there’s also Pseudomonas aeruginosa, which grows pretty much anywhere, even sterile water containers.

By: Sean

Sean — Thu, 26 Jan 2006 20:21:11 +0000

I don’t think that even D. rad could survive if, say, the neutron were lighter than the proton, or the vacuum energy were at the Planck scale. But I do agree that many anthropic arguments rely to heavily on extrapolations about our local forms of life.

By: Elliot

Elliot — Thu, 26 Jan 2006 19:10:26 +0000

Doesn’t the existence of more extreme forms of life tend to “relax” any anthropic constraints on fundamental parameters making the anthropic principle less predictive. In particular if complex information processing was “discovered” in a non-dna based/non-hydrocarbon environment it would seem to me that the Anthropeople would have some “splaning to do”.

Elliot

By: Sean

Sean — Thu, 26 Jan 2006 17:07:58 +0000

Having been exposed to a wide variety of science-fiction disaster scenarios, I’d definitely be reluctant to bring new organisms to other planets unless we were absolutely sure what we were doing. In particular, we would want to avoid doing damage to any existing biological molecules, even if they hadn’t come together to form life. At least, this should be true until we’ve colonized a few hundred different star systems and have planets to waste.

By: Dumb Biologist

Dumb Biologist — Thu, 26 Jan 2006 16:52:40 +0000

I guess I’d worry that we don’t really understand what “life” is very well, because our typical “carbon chauvinism” and “cellular chauvinism”, a direct fuction of having an n of 1 for the existence of “life” in the universe, rather limits our perspective. That’s not to say it isn’t an entirely reasonable perspective, as carbon is the element that allows for the greatest diversity of compounds of the sort we think are needed to build the complex components of living systems, and you’d think that the smallest units of any form of life ought to be somehow discrete from the external environment in some kind of “cell”, for a variety of very practical reasons. Even then, it’s tough to say that water is the only solvent in which living systems could arise, maybe silicon could do the job, and so forth. Maybe we wouldn’t be able to recognize an alien life form even if it was sitting right in front of us. These are some pretty fringe ideas, but we can’t discount them out-of-hand, because we know so little about the nature of exobiology, if it exists at all. So, given that it’s hard to know for certain what an alien ecosystem ought to look like, I’d be hesitant to introduce organisms from our biosphere until we’ve devoted a great deal of study to the matter. D. rad. could be a biome-blasting pathogen if dumped on Ceres for all we really know. I personally consider that possibility remote in the extreme, but who can really say?

By: schnitzi

schnitzi — Thu, 26 Jan 2006 06:34:04 +0000

>I’d be pretty hesitant to introduce it to the Martian surface, myself.

Maybe not to Mars, but I’d like to see it sent to some other planet or asteroid. Not even as a prelude to or part of a human visit, but simply as a seed of life. We talk a lot about populating other planets as a way to preserve the human race, but there’s a decided lack of concern about preserving life in general.

By: Uncle Al

Uncle Al — Wed, 25 Jan 2006 21:32:45 +0000

D. radiodurans fouls nuclear reactor primary coolant loops and spent fuel pools, typically surviving 2 MRad acute dose and mostly ignoring integrated doses. 10^7 bacteria/ml at Hanford storage.

Science News 153(21) 325 (1998)
“Something’s Bugging Nuclear Fuel”

http://www.learner.org/channel/courses/biology/units/genom/experts/eisen.html

Lest we get all high and mighty about the brave scout, remember that Serratia marcescens thrives within “sterilized” saline breast implants. Lots of other bugs do too, but this but this bug is brilliant crimson.

Google
“Serratia marcescens” implants 821 hits

By: Dumb Biologist

Dumb Biologist — Wed, 25 Jan 2006 19:46:19 +0000

As it’s a bacterium, it’s likely its ancestor came from Earth, not someplace else, unless the common ancester of archaea and bacteria came from Mars (or elsewhere), eubacteria evolved independently on Earth and Mars, and then some D. radiodurans made the jump to Earth after, say, an impact. Not impossible, but damned unlikely.

I’d be pretty hesitant to introduce it to the Martian surface, myself.

By: spyder

spyder — Wed, 25 Jan 2006 18:36:45 +0000

Thanks for reminding me of the May 1991 issue of LIFE magazine. It was in that issue that i first read about the plan for terraforming Mars into a resource. D-Rad will be its progenitor? D-Rad as ID??

By: D. Rad

D. Rad — Wed, 25 Jan 2006 18:12:12 +0000

yes we survive very well evolution is nice that way personally i find your use of extreme to describe our home rather prejudicial sean we are just tolerant of a wide range of environments the only place we cannot survive is the comments on posts about women in science

By: Peter Behroozi

Peter Behroozi — Wed, 25 Jan 2006 18:04:57 +0000

From the listed qualities (extreme temperature variation, survival in vacuum, dehydration, etc.), it might even have come from Mars in the first place.