NASA Science News for Dec. 2, 2010
Astrobiologists have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. The microorganism, which lives in California's Mono Lake, substitutes arsenic for phosphorus in the backbone of its DNA.
FULL STORY at
http://science.nasa.gov/science-news/science-at-nasa/2010/02dec_monolake/