Sciencemadness Discussion Board

Alien Invasion?

hissingnoise - 2-12-2010 at 13:21

They're already here!

http://www.huffingtonpost.com/2010/12/02/nasa-new-life-arsen...



Sedit - 2-12-2010 at 14:45

So do I understand correctly that these creatures can live with NO Phosphorus at all? Is there DNA arsenic based instead? That would indeed be a great discovery if you ask me.

chemoleo - 2-12-2010 at 16:22

Personally I think this is way overrated.
Clearly, the bacteria (extremophiles) have just evolved to tolerate As, and substitute it for P in places where it is harmless (to quote, 'they grew on a lean diet of P, but rich in As), despite the somewhat alternate chemistries with As. I'd doubt these bacteria would survive right away only on As , in the absence of P. It starts with energy metabolism (ATP), moving on to DNA nucleotides (phosphate backbone) - transcription (RNA)- all of the necessary proteins that work with these would have to adapt, alternate chemistries evolved etc. Takes millions of years to evolve.
So, evolution started with P, and adapted to As as far as possble. I bet, given enough time, bacteria could also be grown in pools containing selenium instead of sulfur. Indeed, even the E. coli, the microbiologist workhorse, happily incorporates selenomethionine into proteins instead of normal methionine!
Hmm... that might be an idea for a grant! :)

gutter_ca - 2-12-2010 at 16:33

Yeah, they have not managed to prove that this can occur in a complete abscence of phosphorus.

UnintentionalChaos - 2-12-2010 at 16:43

I have requested the original article from Science in references.

Sedit - 2-12-2010 at 17:17

Thanks UC that would be great to read the full artical instead of some fluff piece written by someone who dont know a bacteria from a virus...
Quote:
2:55 PM ET Experiment Conducted In A LabNASA explains how the experiment was conducted:


"The newly discovered microbe, strain GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria. In the laboratory, the researchers successfully grew microbes from the lake on a diet that was very lean on phosphorus, but included generous helpings of arsenic. When researchers removed the phosphorus and replaced it with arsenic the microbes continued to grow. Subsequent analyses indicated that the arsenic was being used to produce the building blocks of new GFAJ-1 cells."


I dunno chemleo Im as skeptical as you but it seems to suggest that they can survive in complete absence of P meaning in order to divide they are going to have to incorperate Arsneic into there DNA. If that proves to be true then, im sure as you know, it isn't over rated its the first step in many to understanding evolution of bacteria like you described.

Imagine first doing away with P and then slowly follow with doing away with S and replace that with Se. If that can be done it would create a bacteria the for all relative reasons it would be alien to our current understanding of life. What if it progressed to completely do away with Carbon replacing with Si, imagine the possibilitys... Yeh I know Im a dreamer but its just food for thought.

chemoleo - 2-12-2010 at 17:42

http://en.wikipedia.org/wiki/Felisa_Wolfe-Simon

She clearly thought, wow, 'I deserve a wiki entry'!
Quote:
Under arsenic growth conditions, the cells were found to reach 0.19 percent arsenic by dry weight rather than 0.001 percent in the controls.[5] One of the reasons this result is unexpected is because arsenate is generally unstable in water, with a half-life measured in minutes. If it is correct that bacterium GFAJ-1 uses arsenate in its DNA and other biomolecules, then it must have found a way to stabilize arsenate or otherwise work around this limitation. Wolfe-Simon speculates that this stability might be accomplished in part by isolating some arsenate containing molecules in large vacuole compartments rich in poly-β-hydroxybutyrate that GFAJ-1 develops when cultured in arsenic but not when cultured in phosphorus


Hmm, so arsenate is isolated in vacuole like compartments? I thought it was incorporated into the very structure of proteins, DNA, RNA, and metabolites?
I think tomorrow I'll check the original paper!

Sedit - 2-12-2010 at 18:12

Yeh without the full paper its hard to come to any sort of conclusion so until then I guess its a wait and see. I do like that they mention incorperation into DNA though its really got my noodle going as to how long it would take with a serogate species to develop a simular trait.

DDTea - 2-12-2010 at 20:57

Here's my little theory about life: the development of living macromolecules ("chemical evolution") does not simply obey the second law of thermodynamics, it is a consequence of the second law. From what we understand of our own solar system, the sun is the ultimate source of energy (or at least the most important one). With that being defined as the system, then entropy does increase with evolution (contrary to what creationists say).

So why not extend that to say that given enough time, complex macromolecules *will* form in order to increase entropy? In that light, arsenic bacteria doesn't surprise me much. Still awesome! Maybe we'll discover life forms made out of iron. I think that would be very ironic.

pneumatician - 26-11-2014 at 19:15

https://sites.google.com/site/asanthoshkumar70/what-s-new-in...

Little_Ghost_again - 17-12-2014 at 17:18

Yeah its interesting but nothing that special. anywhere you have a niche there will be an organism that uses it.
What is an alien? We have all kinds here on earth if you look at it with open eyes. Fungi, very very strange they sit between plant an animal but dont actually fit anyone single definition.
Viruses.
For me these are the real aliens, they are not alive in any accepted or true way and yet they are clearly not dead either.
Archea.
So old no real time of origin can be pinpointed.

WOMEN
needs no explanation

So do we define alien as not of this planet or as not meeting some normal parameters? On a universe type scale aliens cant exist, as we are part of the same universe then surely they are simply other forms of (life??).
Prions,
even now we have no real understanding how these simple amino acid chains can cause such massive damage.

Phages
Not alive or dead and only use bacteria, even stranger that most bacteria have a phage.
Because of this simple little fact I truly believe if you look long and hard enough you will find something using the niche available.