More Arsenic for you
The news broke even before it was reported in all the major news channels. The usual science networks were already buzzing with impending announcement from NASA about some new, possibly revolutionary discovery on extraterrestrial life. Science nerds across the world buzzed with speculations on what the discovery actually was and people tuned into web-based NASA TV at the precise moment of its announcement as if it were the playoffs. And when the news finally broke, no one was really surprised. Perhaps some were a little disappointed.
The core of the new discovery is deceptively simple. The team led by Felisa Wolfe-Simon, a NASA astrobiology research fellow, found a new proteobacteria capable of integrating arsenic into its system, replacing all or many of its phosphorus constituents with its little brother on the table of elements. They did it by first sampling the bacterium at the arsenic-filled Lake Mono in California. They then gradually replaced phosphate in the medium with arsenic. Apparently, arsenic’s ability of to integrate easily into living systems not only lends to its toxicity, but allows the proteobacteria (now named GFAJ-1) to possibly use it as a replacement for phosphorus.
Understandably some people were disappointed with the nature of the announcement as a bacteria capable of living on arsenic doesn’t quite have the sci-fi edge of a new alien civilization hovering just outside the solar system. But, believe me, this might be one of the pivotal moments in a century of life sciences. That is, if they follow through on the research. These days, most educated people do not doubt that life as we know it exists as combination of well-known molecular components, coming together in an incredibly complex mesh of interlocked mechanisms. But the common understanding of life and its constituents may be an illusion.
The truth is, we still do not have a very clear understanding of what life is and how it works. We certainly don’t know whether it’s defined by set of parts (like carbon, phosphorus, nitrogen, etc.) or defined by a relationship between a set of parts–irrespective of the parts themselves. The recent paper might prove to be a first step toward a view of life based on systems and relationships rather than components. If life is about systems and the energy on which they run, what’s stopping us from thinking about systems formed from even weirder substitutes?
-comic via xkcd
It’s not all roses and arsenic at the party though. From what I’ve seen of the paper so far, the results are vague. There is a chance that the GFAJ-1 cultures might be cannibalizing phosphorus from dead cells within the culture to make up for its absence in the environment. There is also no definitive statement on whether arsenic had integrated into the DNA backbone and replaced the phosphate there. And then there’s the reduced 60% growth rate of the arsenic-integrated cell culture, which is expected, but lack clear numbers.
Whether you are a skeptic or a supporter of the new discovery, one thing is certain. We need to Give Felisa A Job so she can continue studying GFAJ-1. After all, she picked these initials for the new strain for that exact reason.
