Yosemite Bacteria Use Toxic Chemical to Make Alien DNA - NBC Bay Area

Yosemite Bacteria Use Toxic Chemical to Make Alien DNA

"The definition of life has just expanded," says NASA expert



    Despite widespread rumors that NASA was unveiling proof of alien life this week, the truth is actually not so far off.

    Instead, NASA unveiled the discovery of an organism closer to home and just as strange. Astrobiologists studying organisms at Mono Lake in California's Yosemite National Park found bacteria that incorporate arsenic into their chemical composition.

    This shakes the very foundation of what scientists believe are the basic building blocks of life. Only a few essential elements are needed to create life: oxygen, hydrogen, carbon, nitrogen, sulfur and phosphorus.

    This strain of microbe, known as GFAJ-1, uses arsenic in the place of phosphorus, substituting the similarly structured element in internal components, including DNA and RNA, which are the blueprints for the organism.

    "The definition of life has just expanded," said Ed Weiler, NASA's associate administrator for the Science Mission Directorate in a statement. "As we pursue our efforts to seek signs of life in the solar system, we have to think more broadly, more diversely and consider life as we do not know it."

    Researchers had previously known that certain organisms could grow with the presence of arsenic, but the study, published in the current issue of Science, is the first to document that arsenic was actually taken up and incorporated by the microbe into its internal compositions. Arsenic would have replaced phosphorus internally for use in the organism's cell membranes and proteins as well as its DNA and RNA.

    The research focused on Mono Lake due to its extreme conditions, including high levels of salt too high for fish, high alkalinity and high levels of arsenic -- all are considered toxic conditions for life.

    "The idea of alternative biochemistries for life is common in science fiction," said Director of NASA Astrobiology Institute Carl Pilcher in a statement. "Until now a life form using arsenic as a building block was only theoretical, but now we know such life exists in Mono Lake."

    Researchers collaborated from the USGS, Arizona State University, the Lawrence Livermore National Laboratory, Duquesne University and the Stanford Synchroton Radiation Lightsource.

    "Our findings are a reminder that life-as-we-know-it could be much more flexible than we generally assume or can imagine," Felisa Wolfe-Simon, co-author of the study and researcher, told Arizona State University News. "Yet, this story isn't about arsenic or Mono Lake. If something here on Earth can do something so unexpected, what else can life do that we haven’t seen yet? Now is the time to find out."