02 December 2010

Life but not as we’ve known it


NASA scientists have discovered an alien kind of life but not in space….

According to National Geographic a new species of bacteria found in California's Mono Lake is the first known life-form that uses arsenic to make its DNA.

Dubbed the GFAJ-1 strain, the bacteria can substitute arsenic for phosphorus, one of the six main "building blocks" for most known life. (The others being carbon, hydrogen, oxygen, nitrogen, and calcium.)

Arsenic is toxic to most known organisms, in part because it can mimic the chemical properties of phosphorus, allowing the poison to disrupt cellular activity. But the newfound bacteria not only tolerates high concentrations of arsenic, it actually incorporates the chemical into its cells,


Astrobiologists found the arsenic-based bacteria while looking for a possible "second genesis" of life on Earth. The scientists were hoping to find evidence of a "shadow biosphere," sometimes called Life 2.0. Such a discovery would prove that, before life as we know it came to dominate the globe, the world had actually seen a separate, independent origin of life.

Despite their oddity, however, the bacteria are genetically too similar to ordinary life to truly be descendents of a second genesis.

Still, the GFAJ-1 strain might be called the most unusual of the extremophiles,

Extremophiles are no so unusual – No matter how tough the environment there is usually something that will adapt to live there. But substituting a key building block of life for a toxic element? Now that IS bloody remarkable!

Or perhaps it is only remarkable in being the first such organism to be discovered. I doubt that there are too many of its sort to be found on earth but in space? Who knows. It’s a shame we won’t live to see their discovery…

9 comments:

Chris H said...

http://news.bbc.co.uk/1/hi/7893414.stm

Give that man a gong!

jams o donnell said...

I agree wholeheartedly Chris

Pagan Sphinx said...

...and then something grows inside Sigourney Weaver, right?

jams o donnell said...

Well maybe not this one, but the angry big brother might!

susan said...

It's possible they're an outpost broadcasting news about our crazy species to their home civilization.

SnoopyTheGoon said...

"It’s a shame we won’t live to see their discovery…"

Who says so? Just start taking arsenic in small doses with breakfast and see how soon you can get used to it.

jams o donnell said...

I can imagine their transmissions - they're jerks don't come!

Hmm mon ami, tempting but I will stick to sugar on my cornflakes!

Ruth said...

There is still some scepticism about this. It is very difficult to prove that the arsenic is incorporated into the DNA in place of phosphorus, or just associated with it in some other way. It's possible there is enough phosphate contamination of the growth medium for normal DNA to be formed.

jams o donnell said...

That's a good point Ruth. I would be most interested to hear more about this