Dr. Ronald Oremland (left) and Dr. Felisa Wolfe-Simon (right) are collecting samples in the field at Mono Lake, Calif. They wade out into the waters of the lake and use a plastic tube pushed into the soft silty sediments to extract a sample of the mud. Dr. Wolfe-Simon used these mud samples to inoculate cultures with the local microbes to test whether there were any microbes that could grow with no phosphorus and high doses of arsenic. (August 2009). Moonrise over Mono Lake. Mono Lake, located in eastern California, is bounded to the west by the Sierra Nevada Mountains. This ancient alkaline lake is known for unusual tufa formations rising from the water's surface (shown here) as well as for its hypersalinity and high concentrations of arsenic. (Sept 2010). This image relates to an article that appeared in the Dec. 2, 2010, issue of Science Express, published by AAAS. The study, by Dr. Felisa Wolfe-Simon at NASA Astrobiology Institute in Menlo Park, Calif., and colleagues was titled, "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus."