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…