Apparently there’s more than one way to build a DNA molecule. And here I shout, “I knew it!” and smile broadly.
Arsenic, would you believe?
It’s from Mono Lake.
One of my unguessable career bits was on the RNA thing—nothing too elevated; but some work was being done in French, which I could translate for my roommate Linda, who was working as lab assistant to a professor who was working on the whole DNA/RNA business. Her job was flipping planaria (flatworms) to see whether they righted themselves to the left or the right, then chopping up worms of the lefthanded religion and feeding them to righthanded flippers, then flipping those worms and seeing whether they converted. This meant a basement full of white enamel pans, bubblers, pumps, etc, and I got drafted preparing slides, washing pans, adjusting bubblers (my fishtank hobby) reading French, grammar-checking the resulting papers and notes, and otherwise being Jill of all trades. I also did some of the observing and recording, which of course would be crosschecked!—so I was sort of in the background of what appeared in—I think it was Science, not Scientific American.
Anyway—shall we say I absorbed a lot of really esoteric stuff, and became better acquainted with flatworms than I would ever have envisioned, not to mention the RNA/DNA thing when it was new. So I did some daydreaming, while scrubbing white enamel pans, on how I would build a helix if I had to build one, and whether the helix we have would be the only possible construction, and didn’t think so, but here we are! It was living in California, all this time!
Not exactly. On reading the paper, it is clear that she selected the beast by gradually increasing the concentration of arsenic in the medium. The beastie grows better without arsenic. From the actual paper in Science Express:
Our data show arsenic-dependent growth by GFAJ-1 (Fig.
1). Growth was accompanied by arsenate uptake and
assimilation into biomolecules including nucleic acids,
proteins and metabolites (Table 1 and 2, Figs. 2 and 3). In
some organisms, arsenic induces specific resistance genes to
cope with its toxicity (7); while some dissimilatory arsenic utilizing microbes can conserve energy for growth from the
oxidation of reduced arsenic species, or ”breathe” AsO4
3-, as a terminal electron acceptor (18). Our study differs because we used arsenic as a selective agent and excluded phosphorus, a
major requirement in all hitherto known organisms. However,
GFAJ-1 is not an obligate arsenophile and it grew
considerably better when provided with P (Fig. 1A, B).
The mystery in all of this is how the beast maintains the integrity of the As-O backbone in the nucleic acid. Why doesn’t it fall apart? She hypothesizes that the poly-β-hydroxybutyrate in the vacuoles disrupts the hydration shell thus protecting the fragile ester bond.
And I should credit you, sainteyebeat, for finding that article! Very interesting stuff. I confess to a flash on the battle saltwater hobbyists fight with cyanobacteria, which are incredibly adaptive, living on just about anything… and having starred in the time of the Permian extinction. Hobbyists get creeped out when they hear that some variations on this semi-animal, semi-plant can crawl…
This little microbe seems to be a case of life finding a niche anywhichway it can, and being quite adaptive, which argues for good opportunities for life developing in many places in a given solar system, but maybe a little trouble devising the means to distinguish it. The adaptability bit would mean capability to develop multi-sided responses to the environment, not inevitably leading to more and more complex organization—until challenged. And planetary geology has ways of challenging organisms into creativity as well as extinction.
“Hobbyists get creeped out when they hear that some variations on this semi-animal, semi-plant can crawl…”
Like slime molds? Always thought those were fascinating things…
Even though this announcement may not have been as exciting as having a bunch of alien humanoids in silver suits landing on the White House lawn, if it makes us conceive of new ways of looking for alien lifeforms, that’s all to the good. And it highlights the fact that there are still new things to be found on Earth.
Did you ever hear of the Wormrunner’s Digest? John Caylor helped me set up a planaria experiment perhaps 50 years ago.
Lord, that rings a bell. This was in about 1963-4, maybe 62-3, somewhere in there, and I can’t remember which prof Linda was working for—could have been Brown: I remember wading through drainage pipes on campus collecting tubifex for that fellow. Linda and I went off to Hopkins together—she studied under McKendrick, who died and orphaned her genetics program—I think he had a heart attack getting off the plane in London.
I’m presently working my way through Precursor and am wondering about how much arsenic is present in atevi DNA-equivalents, considering a substantial amount of their biochemistry is arsenide-based. This plays right into that…
I was excited all day about this news conference thing based on media hype and exciting quotes coming out. This picture sums up my final reaction. Scientist are such a tease. If Cameron were involved at least they’d make them look like tiny tiny blue cat arsenics somehow and it would be in 3D and I could relate to it and stuff. Not in the budget I guess.
Lol, sweetbo, the chance we’ll find *organized* life is not so high!
But honestly, the kitteh is more ‘organized’ than the slurpacious sandworm!
Did I mention that scientists after decades of searching have finally gotten a specimen of the giant Palouse earthworm (10 inches) from fields right near us?
Tiny, tiny blue cat arsenics? Hahaha! Well, except I’m not overly fond of arsenic and I’m fairly average sized. 🙂
That there should be a new (well, old and unknown) micro-critter-plant-whatsits that is at all capable of living in ways we’d thought impossible, and apparently with some uniquely odd DNA or RNA analogues (or alterations?) — that’s fascinating. Right here on Earth there are more possibilities for life than we’d guessed. Therefore, what might exist on some other planets could be very different, yet similar enough, and built from whatever workable variations.on chemistry could be workable.
What I’d gained from a recent rematch of Carl Sagan’s Cosmos, and a documentary or two on early Earth life, is that some very strange forms, unlike any current animals, were very popular for a very long time. So again, lots of other lifeforms are possible within plain old Earth DNA. — But if chemistry makes other structures that could be a viable biological “building platform” and biological “software” or “firmware,” then they probably have been tried by nature somewhere in the universe.
That increases the chances we could find some kind of life, and some kind of intelligent life out there. Whether we and they would be mutually recognizable and comprehensible, and whether there would be competition or cooperation or avoidance, will remain to be seen.
But wow, what exciting possibilities and news.
Do the new critters like old lace? 😉 …lol, “new” when they’re likely far older than our species…or even our phylum. Wow.
That’s all I had on short notice. xkcd did a much better summery of what could have been done differently and for very little cost. If furry blue cat arsenics couldn’t be pulled off that is. And that so totally could have happened. 0_0
Xkcd.com is great. Geeky, funny, sometimes sweet, sometimes slightly profane, but worth a look, always. — I’ll have to see what he posted, haven’t checked in a while. He’s also a scifi fan, so he might even bump into us all at times. For those who don’t knowthe guy is a math and physics postgrad. Recommended.
I was rather disappointed myself after reading some of the lighter, hype articles announcing that NASA planned to announce a major discovery that was about arsenic-based DNA to then read on the NYTs website that it was arsenic subbed in for phosphorus and the DNA still pretty much, sorta worked but not so well. Yes, still an important discovery, but I was hoping for a second, different genetic base for DNA rather than what sounds most plausibly as our standard, all earth-life known DNA set-up.
I’ve operated on the premise that we’ll find that most everything on a given planet will tend to work tolerably the same, because of plate tectonics on a warm planet—things tend to get together, and DNA structure is a pretty flexible, competitive system. It’s highly conceivable that, genetically speaking, nature’s not going to find a much better one, as it’s not found an improvement on the wing, for instance, and that the 5-digit limb structure, however modified to hooves, flippers, etc, tends to be pretty stubbornly in the design, because it works well—not that it’s chemically necessary. When certain basic chemicals get together as a structure, it’s going to compete well in a wide range of environments, and over the long haul of geology, in most environments where development of colonial cells into a cooperative system is at issue, it’s going to compete better and better—because environments where that can happen tend to be warm—(chemistry works faster in warmth)—and if a planet’s warm, it tends to have a molten core, if it has a molten core it has plate tectonics, and if it has that, the plates bump together, fuse and break up over millions of years, producing radical change in the environment and forcing life or semilife to change or lose. So adaptability is good, and the higher up the route to awareness you get, the more it is good. Not saying DNA-like stuff HAS to be everywhere—but it’s very efficient, and it’s got a good chance of winning out. In some senses you can look on microlife as particularly successful nanomachines, and they have to pursue food or energy, be it only seeking light, and they have to reproduce, because one immortal but non-reproducing microbe is just going to get scarfed down by something that is hungry and prevalent.
These are my random thoughts, at least.
having largely forgotten a fair chunk of my old high school biology — and having grown up in california — i actually find it rather prophetic that they find this off-kilter life form in poor over stressed mono lake.
It seems other scientists are irked and poking holes in the science paper on this.
http://news.yahoo.com/s/yblog_thelookout/20101208/sc_yblog_thelookout/scientists-poking-holes-in-nasas-arsenic-eating-microbe-discovery
If they truly have not found a lifeform that lives in a new, previously unguessed at way, then OK. If it still may be a game changer, then OK too. Let this get tested and reasoned out. That’s how science is supposed to work.
It is still just as exciting that there *could be* something which uses processes for life that we hadn’t thought were possible. So what else could be possible?
I scanned through a few of the comments. The usual outright lunacy and idiocy from people clearly not using their brains or not thinking beyond their preconceptions and pet peeves. The one that I thought was truly bad was the nitwit who thought science papers / reporting should be censored, that some things shouldn’t be worth researching, or scientists shouldn’t research on whatever they’d like to investigate. That was just…straight out of the Dark Ages and superstition and foolishness. Now, I’d agree that some things might not be the best subjects for study. Some things may be hurtful to people or animals. Some things may be on the trivial side. If you’re going to do a research study, then have some merit to it and use good judgment and some compassion. But then, some things truly are worth study. For that matter, observations of what really is out there, including in bad situations, can be used for benefit. — And entirely aside from that, sometimes the most basic questions or simplest experiments can lead to real discoveries, even nowadays. — I shouldn’t have been astonished at the person who thought censorship of science was a good idea. That person wasn’t just stirring the pot, either; it was a sincere opinion, just not a very sensible one.
I hope their science will be more careful next time. I hope they (and others) keep looking for what we don’t know is possible. It seems eminently worth it to find out there’s more to life (in whatever sense) than we knew. If we’re wrong and have to (gasp!) change our ways of thinking toward what is really there, then that’s fair enough.
I am not so much worried about hostile aliens wanting to eat me for breakfast, anyway. It seems there are more than enough humans who’d like to do that in a figurative sense as it is. If we can’t learn to get along down here on this little garden spot oasis in the vast star-desert, then I don’t think marauding aliens are really going to be an issue any time soon.
:: Climbing down from soapbox. Next, please. ::
BlueCatShip: I’m going to disagree with you a bit here. You said, “If you’re going to do a research study, then have some merit to it and use good judgment and some compassion.” I say, “Who gets to decide what has merit? What is good judgment? What does and does not count as compassion, and who gets to make that decision?”
Case in point: some years ago I was reading about a crusading Congresscritter whose main hobby appeared to be looking over research grants and pointing out the ones he thought were wastes of the taxpayers’ money. He’d make a list of ten or so of these each budget year. The one I recall was a study of tree girths in Costa Rica, a couple hundred thousand dollars to measure trees over the course of a year or so. He went on at length about how trivial it all was.
It isn’t trivial if you want to know about growth rates in that type of forest… especially if you’re part of the forest industry or the parks industry or a wildlife conservation industry or even the agricultural industry…
My point is that measuring the worth of science based on ‘triviality’ or ‘compassion’ or ‘merit’ is using yardsticks too subjective to provide decent data. Measuring the science on whether it adequately answers the question asked, however, is. How that answer is used may not be immediately obvious — after all, they were looking at Drosophila genetics for decades, before they discovered that about forty percent of their data would translate to human genomic studies. Nothing trivial about *that*.
Tell that to crusading Congresscritters, though.
I haven’t read a lot on the arsenic-using bacteria yet (they don’t eat arsenic, though. They use it in metabolic pathways the way other critters use phosporus. Or that’s what the original paper claimed. Why is that distinction so difficult for the public to grasp?) I do know that several scientists have ‘eviscerated’ the original paper; must follow up on their critiques. I am betting, however, that if there are major problems in methodology in the original experiments, as claimed, that someone out there will repeat said experiments with stricter controls.
I’m looking forward to those results!
uh-oh, flame wars started over the bacteria that can live in arsenic ..http://www.spacedaily.com/reports/NASAs_arsenic-eating_life_form_gets_a_second_look_999.html
Peer review is how science lumbers along—but it has to be peer review, not trial by blog. You get your facts together, run checks, and do another article, f’ gosh sakes, not dash off a blog entry and get into an internet spitting contest, though I’m sure even the scientist who did the blogging anticipated making the evening news with it, but ‘Rosie’ has somewhat exposed a certain unseemly bias of her own, and used some ad hominem arguments in the process. [Ad hominem—attacking the person, not actually engaging the argument itself, for those of you who didn’t have debate class: it’s a variety of logical flaw.]
Your randomly chosen political/legislative debate or talk show should provide numerous examples of ad hominem arguments. I’m not sure where one could look for contemporary examples of ad rem arguments. [Ad rem—to the matter, addressing the substance of the issue]. Required Philosophy courses may be the most important part of a liberal arts education. Rigorous thinking and intellectual honesty are amongst the most important collateral damage of our infotainment cycles.