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Surprising Mono Lake discovery changes conceptions of life

December 7, 2010

A scanning electron micrograph (right) shows the GFAJ-1 strain grown with arsenic found in Mono Lake (above) by astrobiologists from NASA. The bacteria uses arsenic, not phosphorous, as a basic building block for its life. The discovery could change the entire understanding of how life is formed from its elemental properties as well as the search for extraterrestrial life. Photo by Ken Babione

The discovery of an arsenic-loving bacteria swimming in Mono Lake may change the basic understanding of how life is formed from its fundamental elements.
The National Aeronautics and Space Administration announced Thursday that astrobiologists have found a bacteria that uses otherwise poisonous arsenic instead of phosphorus as apart of its DNA. Until this recent discovery at the famous lake, phosphorous has been believed to be an essential component of DNA and life, and life would not be possible without the chemical element.
It has also been reported that the discovery will change the way scientists search for extraterrestrial life forms. The Mono Lake Committee hopes the discovery will revamp interest in scientific research in the area and serve as an example to the value of preservation of natural resources.
“The definition of life has just expanded,” said Ed Weiler, NASA’s associate administrator for the Science Mission Directorate on the agency’s website.
Astrobiologists, led by Felisa Wolfe-Simon, a NASA research fellow and geomicrobiologist, have named the bacteria, GFAJ-1.
“It is the first time in the history of biology that there’s been anything found that can use one of the different elements in the basic structure,” said Paul Davies, the director of BEYOND: Center for Fundamental Concepts in Science at Arizona State University in Tempe.
“If something here on Earth can do something so unexpected – that breaks the unity of biochemistry – what else can life do that we haven’t seen yet?” Wolfe-Simon said on the NASA website.
In a press conference hosted by NASA on Thursday, scientists reported this discovery does not necessarily prove a “second genesis” but it is promoting the theory of a “shadow biosphere,” meaning that life on Earth did not start twice, but there may be more than one way for life to exist. The science fiction-esque term “shadow biosphere” was coined in 2005 by University of Colorado philosopher and astrobiologist Carol Cleland, who defines it as “undiscovered alternative forms of microbial life.”
The idea of alternative life forms is not a new one, but evidently one that had not been followed. At a BEYOND seminar in 2004, Wolfe-Simon proposed the idea that Mono Lake, with its high arsenic and saline content, may hold potential for hosting a shadow biosphere. Arsenic, while poisonous to life, has a basal chemical structure very similar to phosphorous.
The abstract to Wolfe-Simon’s research article, “A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus,” printed in Science magazine, states, “Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. Although these six elements make up nucleic acids, proteins and lipids and thus the bulk of living matter, it is theoretically possible that some other elements in the periodic table could serve the same functions.”
Astrobiology, as defined by NASA, is the study of the origin, evolution, distribution, and future of life in the universe.
Mono Lake has played a prominent role in the field of astrobiology since the 1990s when the ancient, 700,000-year-old body of water with no outlet was found to be similar to lake beds on Mars – that is, in fact, if lakes existed on Mars, said Mono Lake Committee Information Specialist Greg Reis by phone Friday. The lake is fed by mineral-rich, mountain run-off only and has no outlet, so the lake slowly evaporates leaving behind dense mineral deposits, which are the famous other-worldly tufa towers at the lake.
Reis said that NASA’s interest in Mono Lake has been ongoing since the idea of a mission to Mars and rovers came to light in the 1990s. He said that as recently as October 2010, members of the Jet Propulsion Laboratory were testing tufa drilling rovers at the lake shore. Reis explained that tufa can trap bacteria and may contain bacteria fossils.
Reis said that the theory is that as Mars slowly dried out, the last places life would have existed would have been in the last places with water. These standing bodies of water would have dried up like Mono Lake is and leave tufa deposits with possible fossils – Martians.
Now, Mono Lake holds the key for the way new or other life forms, on this planet and beyond, will be searched for.
“One of the guiding principals in the search for life on other planets, and of our astrobiology program, is that we should ‘follow the elements,’” Ariel Anbar, professor and biogeochemist at ASU, told the college newspaper. “Felisa’s study teaches us that we ought to think harder about which elements to follow.”
Reis said the discovery has certainly caught the public’s attention, with the Mono Lake Committee’s website traffic tripling since the news of NASA’s discovery broke on Thursday. He said he expects to see a spike in tourism and, hopefully, a revival in scientific interest in the area and its unique properties.
Reis added the discovery is also a testament to the importance of saving natural resources. “This is a great lesson (in conservation). If the lake were allowed to dry up, the organism may never have been found.”

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