Tuesday, December 07, 2010

Arsenic-based life forms: Fact or fiction?

The biggest science news of the past week probably has to be NASA's press release claiming to have isolated a bacterium that substitutes arsenic for phosphorus on its macromolecules and metabolites. (Wolfe-Simon et al. 2010, A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus.)

As things stand, many scientists are openly skeptical of the claims made in the paper.

That is understandable, given the potential impact on biology. If the results are shown to be right, this might open a whole new field of research on arsenic-based life forms (and possibly the Nobel Prize in the near future). E.g. The discoverers of graphene were awarded the 2010 Physics Nobel a mere six years after their publication in Science.

And the authors' response to the online critics?

"If we are wrong, then other scientists should be motivated to reproduce our findings. If we are right (and I am strongly convinced that we are) our competitors will agree and help to advance our understanding of this phenomenon. I am eager for them to do so." - Ronald Oremland, US Geological Survey.

Heh, the scientific method is at work here.

This whole episode reminded me of a question back in the days of my JC S-paper chemistry class where we were asked to suggest alternative elements that could potentially replace those currently in use by nature. Can we substitute carbon with silicon? Phosphorous with arsenic? Would there be any problems with these changes under earth's atmosphere and conditions?

Maybe I should revisit my old A level notes (if I still have them somewhere) to look for old theories to test. Maybe I can get something useful (like a Science publication) out of them. Like the SN2 reaction mechanism. Who could have thought there would be an unexpected 'roundabout' mechanism in addition to the traditional 'inverted umbrella' pathway?


Natasha Papousek said...

I like to think that there could be arsenic-based life forms...but as my husband, the astronomer said, "Either it's the greatest thing to happen in science....or it's not..."

He's not too bound to the conclusions of this paper. But I, the non-scientist, think it is so tantalizing. And if this is true, could there be life-forms based on other elements in different but extreme environments?

JeLiBe@nZ said...

Just a heads-up. The original scientific paper reported a gradual weaning of the bacteria from carbon to arsenic. The bacteria wasn't discovered intact with arsenic.

as for how long this "new" life form can survive without disruption to its metabolism, DNA replication , propagation and still maintain integrity as a bacterium remains to be seen.