“Alien” life form…
In California, naturally.
All joking aside, this is fascinating. It’s a bacteria that can incorporate arsenic rather than phosphorus into its DNA, expanding the possibilities for the basic building blocks of life.
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It’s thrilling. John Podhoretz at Contentions calls it the biggest news of the new century. But just watch — before you blink you’ll be seeing terms like “phosphorcentric” being tossed around.
I half expect to see Kirk and Spock beam down to this lake and take a sample forward into time to save the universe from apocalyptic disaster.
“Our findings are a reminder that life-as-we-know-it could be much more flexible than we generally assume or can imagine,” said Wolfe-Simon.”
… Except for global warming. Can’t have any flexibility there.
It’s life, but not as we know it.
Nancy,
This is OT, but related to your last comment. The climate conferences usually get lots of coverage here in Germany, but I didn’t see any tonight. Maybe the pictures of climate activists sipping tequilla on the beach would be a little unsettling to the Europeans who have been stranded by the snow. They did report a 500-km traffic jam around Brussels. Couldn’t happen to a nicer city.
It’s life, but not as we know it.
Exactly. This could dramatically increase the number of planets and moons where life might have evolved. Up till now, we’ve mainly been looking for worlds with Earth-like conditions, either today or in the distant past. Earth’s environment was very different a billion or more years ago. Human time travelers would have to wear spacesuits and bring their own oxygen supply. Life itself has sculpted the environment into what we know today.
Life has erased the scaffolding it used to create itself…
there were probably MANY less robust systems that at the beginning when competition was less, could function. eventually, almost all of them have been taken over, weeded out, or removed…
I have some remarkable math and simulation work in the organizational area, but not being approved its just a waste of my life and work..
“Attention everyone: in order to cut down on our carbon footprint, all lifeforms will now be silicon-based.”
I am offended for these poor bacteria that some people put a negative spin on the existence of arsenic. Lawsuit!!
Mono Lake, for those of you who don’t know the history, has an interesting story. Just to the north of the Owens Valley, its water was not a part of the first project to bring Owens Valley water to Los Angeles, an effort started in 1898 by L.A. Mayor Frederick Eaton and his Water Department Superintendant William Mulholland. That first project was a smashing success for the city of LA but is said to have killed the Owens Valley by taking all its water. Even that large source of water was insufficient to LA’s needs, though and a second aqueduct was completed in 1972 that would bring water to LA from Mono Lake.
This second project dropped the level of Mono Lake to such an extent that a land bridge was created from the shoreline to two islands in the lake, and coyotes were able to cross those land bridges and eat the eggs of birds nesting on the islands.
A biologist studying the danger to the nesting birds raised enough of an outcry to bring the issue before the CA courts in 1984, a suit that eventually found in favor of the nesting birds on the islands and required the level of the lake to be raised 20 feet by reducing flow of Mono Lake water through the LA aqueduct.
Lots of folks in the Owens Valley and around Mono Lake are still angry about LA having bought up all their water rights and take no little satisfaction in the reduced water flow to LA. The coyotes are not happy about the decision, though. F
Is composed of five words, is composed of five words.
And, how far can a dog run into the woods?
How do you pronounce the capital of Kentucky, is it “Lewyville” or “LouISville”?
Is it legal for a man to marry his widow’s sister?
Ah, life’s mysteries.
I thought Dennis Kucinich was from Ohio.
I haven’t read the original article, which may (and presumably does) address the following points, but I’m a little skeptical that this may be overblown. (Are these guys’ grants up for renewal, by any chance?)
1. While arsenic is a congener of phosphorus, and thus formally can replace it to produce analogous compounds, arsenate esters typically hydrolyze much more readily. Thus arsenic-based DNA would be more labile than that based on phosphorus. Maybe the peculiar environment of this bacterium somehow mitigates this effect.
2. Arsenate is toxic to (other) organisms because it uncouples oxidative phosphorylation and also (IIRC) binds covalently to thiols (e.g., cysteine, a critical amino acid). Thus an arsenic-based life form would entail massive changes in biochemistry, far beyond simple substitution of As for P in its DNA. Its entire metabolic machinery would need re-engineering. At a minimum, it would need to compartmentalize arsenic compounds to keep them away from thiols and the machinery of oxidative phosphorylation (arsenylation?), assuming it’s not an anaerobe (big assumption, and probably not warranted). Even if it uses anaerobic metabolism, however, if it produces arsenate triesters analogous to ATP, lability will pose a massive problem. Once again, the bacterium’s peculiar environment in Mono Lake may mitigate this problem.
Alternatively, perhaps the bacterium’s physiology bears at best a tenuous relationship to that of previously known organisms, in which case the considerations are moot. If the bacterium’s energy economy is based on completely different chemistry (i.e., not a simple As for P substitution in, e.g., ATP), then this is indeed a huge discovery. Offhand, this seems unlikely, since the bug can grow on either As or P.
My best guess, in the total absence of any substantive information: the bugs incorporated a small amount of As into their DNA when grown on As in the absence of P. That is an interesting observation, but not such a big deal. How many generations can grow in the absence of any phosphorus?
Occam’s Beard:
That’s beyond my pay grade. Maybe you ought to try to correspond with the authors of the article.
Me, I’m just chuckling over the fact that Dr. Felisa Wolfe-Simon is nicknamed “IronLisa”.
Felisa.
Those wacky biochemists crack me up.
I haven’t read the original article … but I’m a little skeptical…
Read the article, then decide whether you’re still skeptical. I did read it. They’re not grant-sucking morons; they did very good and careful work, and they’re not just overselling “small amount of As into their DNA”. The data in the paper show what looks to me like near-total replacement of phosphorus with arsenic, including in what’s likely to be the backbone of DNA.
It will need to be reproduced by another lab to be rock-solid, like every other major scientific finding needs to be; but the authors have put out a very strong case for an extraordinary replacement of one core element with a normally toxic one. That’s something I wouldn’t have predicted unless I’d seen this paper. And I’ve worked in molecular biology for 28 years.
Occam’s got it: not that big a deal, especially given the bizarre complexity of life all ready observable on earth. The real story here –which journos never report– is that periodically science institutions will gin up a story by dramatizing something fairly prosaic in order to draw attention at funding time. The real message is: we want more money. That so many geek out over transparent announcements like this –especially from NASA– is merely more evidence that in a post-religious culture people will try to find something –anything– to give them a substitute sense of transcendence.
The data in the paper show what looks to me like near-total replacement of phosphorus with arsenic, including in what’s likely to be the backbone of DNA.
Great. I’m glad the data appear to support their conclusions. I don’t have access to the original article; I’m a chemist, not a molecular biologist, and consequently don’t bother subscribing to Science (and am not willing to pay for the article).
“the near total replacement of P by As”
Throughout the bug’s biochemistry? Arsenate esters for the nucleotides, for energy transduction, arsenolipids, the works? Wow. If true, that is a big deal.
My skepticism arises from the physiological equivalent of a scaling-type problem. Doubling every body dimension entails quadrupling some things (e.g., skin) and multiplying others eightfold (e.g., blood supply). This changes relationships between things. Eightfold greater volume generates a greater cooling burden, necessitating a disproportionate increase in some organs (e.g., heart, ears, skin) to help dissipate heat.
Arsenic for phosphorus substitution throughout the bacterium affects some pathways and structures more than others, much like a gigantic physiological kinetic isotope effect.* (For non cognoscenti: if a bond to an element, say hydrogen, is broken in the rate-limiting step of a reaction, substitution of that element by a heavier isotope slows the reaction by an amount related to the ratio of the isotopes’ atomic weights. It is for this reason that bacteria cannot live in pure deuterium oxide; some reactions are slowed, others that don’t meet the criterion above are not. It’s like having the tires on a car rotating at different speeds.)
Here we don’t just have a modest tweak on rates of some reactions, but a relatively whacking great change in reactivity. Arsenate esters are considerably more labile than phosphate ones; this is not a subtle effect. Moreover, arsenic(V) can also undergo reduction to As(III), which covalently binds to thiols (e.g., cysteine esterases). No corresponding reaction exists for phosphorus under physiological conditions (AFAIK).
So, I look forward to learning more about this. As said above, if it’s true, it’s a big deal.
Fascinating and totally unperedictable, so much that I can hardly believe that this was true. DNA was seen as so uniform, basic and universal for all live forms that this means complete reassesment of fundamentals of molecular biology. I would also like very much to see mitochondrion of this creature: how does it produces energy from oxidation, and what it has instead of ATP? ATAs?
“I would also like very much to see mitochondrion of this creature: how does it produces energy from oxidation …”
I thought bacteria don’t have mitochondria.
O what is longer than the way, or what is deeper than the sea?
Or what is louder than a horn, or what is sharper than a thorn?
Or what is greener than the grass, or what is worse than a woman was?
Oh LOVE is longer than the way, and hell is deeper than the sea
Thunder is louder than the horn, and hunger is sharper than a thorn
and poyson is greener than the grass, and the devil is worse than woman was
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Occam, excellent stuff…
I can read the paper where i work, hadn’t taken the time though… while interesting its not going to be too explanatory about a lot. the bio guys are running up against basic problems in their incohesive and often contradictory overall model.
there are some problems you cant use statistics to gleen! in fact there are several things that they don’t work on, or cant bring you to.
“My skepticism arises from the physiological equivalent of a scaling-type problem.”
Yeah, I know — that’s why it’s flabbergasting that this worked at all. Anything like the level of replacement of P by As that they seem to have achieved is not something I would have thought possible, if I hadn’t seen the paper. (I’m familiar with the toxicity of heavy water; one biochemist who isolated heavy-water-sensitive mutants in yeast while at MIT is now a professor here at Caltech. Even 2% heavy water in medium has serious effects on yeast or mice.)
One thing the authors of this study noticed is that the bacteria grown on arsenic show extensive internal vacuolation. Clearly the physiology of these bugs in As-rich medium isn’t equivalent to that in P-rich medium. The authors speculate that lowering the intracellular water concentration by sequestering H20 into the vacuoles may be one way the bacteria survive the change.
Sigh. I should have known that somebody besides myself would do a better job spotting the hidden flaws in the NASA paper. Here’s a critical review of it, which I wish Science’s reviewers had either written (if they didn’t, in fact, write it or its equivalent) or forced NASA to follow up on (if they did write it):
http://rrresearch.blogspot.com/2010/12/arsenic-associated-bacteria-nasas.html