CNN: Did E.T. Finally Phone Home? (NASA press conference today)

[Ellis]

The truth is out there.

NASA is planning to hold a news conference Thursday "to discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life."

The Web is abuzz with speculation about what that cryptic phrase might mean.

"Our guess is that this astrobiological discovery will have something to do with water, evolutionary biology, and aquatic bacteria," the Geek Tech bloggers at PCWorld say.

Gaming and fantasy site Kotaku thinks it could mean life-friendly conditions - or even living organisms - have been found on Saturn's moon Rhea.

"There's only one thing this could mean: NASA has aliens. Now let's just hope they're the friendly, ET-kind of visitors, and not the warlike Klingon types," Stephen Losey wrote (tongue-in-cheek) on FederalTimes.com.

Blogger Jason Kottke analyzed the lineup of scientists slated to appear at the press conference and came up with his own conclusion:

"If I had to guess at what NASA is going to reveal on Thursday, I'd say that they've discovered arsenic on Titan and maybe even detected chemical evidence of bacteria utilizing it for photosynthesis (by following the elements). Or something like that."

Leave it to Discover.com's level-headed Phil Plait to throw a wet space blanket on the hype over the possible discover of extraterrestrial life:

"It seems really unlikely; I don't think they would announce it in this way," he writes. "It would've been under tighter wraps, for one thing. It's more likely they've found a new way life can exist and that evidence for these conditions exists on other worlds. But without more info, I won't speculate any farther than that."

Hmfph. Party pooper.

http://news.blogs.cnn.com/2010/12/01/did-e-t-finally-phone-home/?hpt=C2

[JMS]

How is it astro biological since they found the bacteria on earth?

Discovered in the poisonous Mono Lake, California, this bacteria is made of arsenic, something that was thought to be completely impossible.

http://gizmodo.com/5704158/nasa-finds-new-life

[Larry]

How is it astro biological since they found the bacteria on earth?

It's life, Jim. But not as we know it.

[#98QBKiller]

Interesting...maybe they're announcing a trip in the near future to Europa? However, I thought there was already one scheduled in the next 5-10 years.

[JMS]

It's life, Jim. But not as we know it.

It's the silicon based bacteria you've got to watch out for. Dr Flox thinks he knows the cure for that, but we know he really doesn't. If they announce silicon based bacteria found and hold it up in an open petry dish;; then run for the hills. and bury yourself under one.

[Hubbs]

Can someone please explain this in plain English?

[Vilandil Tasardur]

Can someone please explain this in plain English?

The discovery?

Basically all life is composed of 6 elements; Oxygen, Hydrogen, Phosphorus, Sulfur, Nitrogen, and Carbon. No matter how diverse life is, from the simplest prokaryote to the most complex Elephant or Human or whatever, everything has to have those 6 elements.

These bacteria found in some lake in Cali don't follow the rule. They appear to have no Phosphorus, and instead have lots of arsenic. Arsenic is right below phosphorus on the periodic table, meaning that they have quite similar properties. In this case, it appears that these organisms are living devoid of the element phosphorus by using arsenic in its place. The finding, if it proves to be accurate, is revolutionary because it redefines the parameters believed necessary for life.

[PeterMP]

Actually, it appears they need a little P. They weren't able to grow them on no P.

Presumably, we'd still see PLP.

http://en.wikipedia.org/wiki/Pyridoxal_phosphate

But it appears to be little enough P that they aren't using it for ATP, which is interesting.

[HailYeah]

Is this new? I saw a show a while back where they were studying these bacteria in that lake in Cali. Must be that they were just published so now its official.

The way I understand it, these new bacteria don't have DNA as we think of it. Therefore they most have evolved along a completely different evolutionary path than anything we have known as life up to this point. So, yeah. It could be a pretty big deal.

Correct me if I'm wrong.

[Ellis]

Actually, it appears they need a little P. They weren't able to grow them on no P.

Presumably, we'd still see PLP.

http://en.wikipedia.org/wiki/Pyridoxal_phosphate

But it appears to be little enough P that they aren't using it for ATP, which is interesting.

:pfft:

[Hubbs]

Is this new? I saw a show a while back where they were studying these bacteria in that lake in Cali. Must be that they were just published so now its official.

The way I understand it, these new bacteria don't have DNA as we think of it. Therefore they most have evolved along a completely different evolutionary path than anything we have known as life up to this point. So, yeah. It could be a pretty big deal.

Correct me if I'm wrong.

Hold on. They don't have DNA? Really? Now I'm at least starting to understand why this is news.

[PeterMP]

Is this new? I saw a show a while back where they were studying these bacteria in that lake in Cali. Must be that they were just published so now its official.

The way I understand it, these new bacteria don't have DNA as we think of it. Therefore they most have evolved along a completely different evolutionary path than anything we have known as life up to this point. So, yeah. It could be a pretty big deal.

Correct me if I'm wrong.

(I actually heard from somebody else on this so this is actually new. I'm actually becoming less impressed with this the more I learn.)

It CAN use As and not P in its DNA. It CAN use As and not P in many biological processes, but it WILL use P. P even seems to be preferred.

It only uses As if you starve it for P (as far as we know).

Based on some of its DNA sequence, it can be clearly placed on the evolutionary tree in an "odd" group of "normal" bacteria that there is no reason to believe they were particularly early in the evolutionary game or different. Just an evolutionary off shot evolving to live in a particular environment.

It isn't even clear if other organisms could add As to their DNA IF the As didn't kill us/them.

The big thing is it appears this organism has found away to not be killed by As, and then when starved for P, its enzymes (and other biological processes) are "sloppy" enough to use As, but that last part might be true for essentially every organism they just get killed by the As before it would get to a concentration that they could use it.

The end result is in the presence of As and very low P, you see As in different biological molecules, like DNA, instead of P.

Except to hard core biochemists working on figuring out how they survive high As concentrations I don't think this is going to be very interesting to many people.

[G.A.C.O.L.B.]

Funny, E.T. is on HBO right now. I think the movie has aged pretty well but maybe that's just me.

And that is about all I can add to this discussion.

[Hubbs]

The big thing is it appears this organism has found away to not be killed by As, and then when starved for P, its enzymes (and other biological processes) are "sloppy" enough to use As, but that last part might be true for essentially every organism they just get killed by the As before it would get to a concentration that they could use it.

The end result is in the presence of As and very low P, you see As in different biological molecules, like DNA, instead of P.

Except to hard core biochemists working on figuring out how they survive high As concentrations I don't think this is going to be very interesting to many people.

That still seems like a big deal to me. :whoknows:

[PeterMP]

That still seems like a big deal to me. :whoknows:

Yes and no.

Arsenic is toxic because it likes to bind to your thiols.

http://en.wikipedia.org/wiki/Thiol

Which keeps them from functioning normally and kills you.

The best way to keep something from being toxic is to keep it out. This bacteria doesn't seem to be doing that or it wouldn't do things like put As in its DNA.

So it is either doing something to protect its thiols or doing something to the As to tie it up so it doesn't bind to your thiols. From a strict biochemistry sense, that's interesting.

From an ecological stand point, it might be interesting in terms of detoxifying As contamination.

Other than that it isn't that interesting. Biological systems frequently do things we don't "expect" because they haven't evolved to NOT do them.

A very basic enzyme, hexokinase, is a good example. ATP is your energy source, but can be broken down in a wasteful manner. Hexokinase uses ATP and another molecule. It does something only in the presence of the other molecule to "protect" the ATP so that you don't end up wasting all of your energy.

The hexokinase is "specific" for the other molecule that it also uses and so other biologically relevant molecules don't have the same affect and you don't waste your ATP.

However, it is very easy for us "trick" the enzyme by using molecules that it hasn't evolved to function with that aren't biologically relevant to get it break down ATP in a wasteful manner.

The hexokinase hasn't evolved NOT to do it because its never been an issue because living organisms never see those molecules.

Most likely the enzyme that makes DNA, DNA polymerase, (really not just this enzyme, but enzymes before it that make the things it uses for people that really care), put As in the DNA because it hasn't evolved NOT to do it because no organism (even this one) ever sees the conditions they are growing it under in the lab where it puts the As in instead of the P.

If I could survive the As levels that it does and was placed in similar conditions, I'd likely end up with As in my DNA because my enzymes have not evolved NOT to do it because they are conditions that they've never seen.

As far as we know, the enzymes in this organisms aren't specific for As vs. P. They are just sloppy enough to use both and might even favor P.

That might be true for essentially all organisms with respect to P using enzymes.

The interesting part isnt' the P vs. As related enzymes, but those that need thiols to work, and how are they different/replaced and/or how is this bacteria interacting with the As.

[DjTj]

The interesting part isnt' the P vs. As related enzymes, but those that need thiols to work, and how are they different/replaced and/or how is this bacteria interacting with the As.

That's probably the interesting part from the biochemistry perspective, but from the astrobiology perspective, this real-world proof that life can develop using an element outside of the typical carbon, oxygen, hydrogen, nitrogen, and phosphorous building blocks changes the equation for what they are looking for in a spectroscopic profile. Previously, any planet without those elements in some abundance would be immediately dismissed as a candidate for life, but now they don't need to rule out planets that have arsenic but no phosphorous, and it makes it more likely that silicon or sulfur or other elements may be able to substitute for the generally accepted building blocks of life.

At the very least, it should help some people get funding for experimenting with building DNA using those other elements.

[PeterMP]

That's probably the interesting part from the biochemistry perspective, but from the astrobiology perspective, this real-world proof that life can develop using an element outside of the typical carbon, oxygen, hydrogen, nitrogen, and phosphorous building blocks changes the equation for what they are looking for in a spectroscopic profile. Previously, any planet without those elements in some abundance would be immediately dismissed as a candidate for life, but now they don't need to rule out planets that have arsenic but no phosphorous, and it makes it more likely that silicon or sulfur or other elements may be able to substitute for the generally accepted building blocks of life.

At the very least, it should help some people get funding for experimenting with building DNA using those other elements.

No (well not really)

The difference is in the chemical similarity. Nobody NOW would tell you they'd have an issue with a more S based life in replace of O. We see a large amount of variability in terms of S in biochemistry and people already talk about non-water based solvents, which means minimal S and less O, potentially to the point of no O.

Si can't replace C because it doesn't have the same chemical flexibility in terms of making bonds.

There are REAL chemical limits to what some elements can do. A P/N life form (instead of C) is much more likely than an Si form.

And the idea of As instead of P isn't novel with this organism.

http://en.wikipedia.org/wiki/Hypothetical_types_of_biochemistry

"Arsenic, which is chemically similar to phosphorus, while poisonous for most Earth life, is incorporated into the biochemistry of some organisms.[9] Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes (Chrysiogenes arsenatis).[10] Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy. It has been speculated that the earliest life on Earth may have used arsenic in place of phosphorus in the backbone of its DNA.[11] A study released by NASA has revealed that a bacteria in Mono Lake, California may employ such 'arsenic DNA' when cultured without phosphorus.[12][13]"

The last sentence was added sometime today as I've already looked at that link today and it wasn't there before.

The people that think about this don't believe that life on Earth started using S and P. I doubt that anybody would rule out a planet for not having P as a place that might have life.