Dec. 2, 2010:? NASA-supported researchers have discovered the first known micro-organism can Earth thrive and reproduce with the toxic chemical arsenic on the. Arsenic for phosphorus in the backbone of the micro-organisms, which Lake Mono lives in California, replaced its DNA and other cellular components.
"The definition of life only has expanded," said Ed Weiler, NASA associate administrator for the Science Mission Directorate of the Agency headquarters in Washington. "As we pursue our efforts, to seek signs of life in the solar system, must we think more on the whole, more differently and look at life as we know it not."
This statement of a make-up is alternative biochemistry biology textbooks change and expand the scope of the search for life beyond the Earth. The research is published in this week Science Express Edition.
Carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur are the six basic building blocks of all known forms of life on Earth. Phosphorus is part of the chemical backbone of DNA and RNA, the structures that carry genetic instructions for life, and is regarded as an essential element for all living cells.
Phosphorus is a central component of the energy-carrying molecule in all cells (adenosine triphosphate) and also the phospholipids which form all cell membranes. Arsenic, which is chemically similar to phosphorus is toxic for most life on Earth. Arsenic interferes with metabolic pathways, since it is chemically similar to phosphate.
"We know that some microbes can breathe arsenic, but what we found is a germ of new construction-parts of itself of arsenic, to do something", said Felisa Wolfe-Simon, NASA Astrobiology research fellow in residence at the U.S. Geological Survey in Menlo Park California, and scientists lead the research team. "If something here on earth so unexpected something can do, can what life do otherwise, that we haven't seen?"
The newly discovered germ, root GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria. In the lab, the researchers successfully grew microbes from the Lake on a diet, which was very lean on phosphorus, but generous servings of arsenic. If the phosphorus removed researchers and replaced with arsenic microbes continue to grow it. Later analysis showed that the arsenic was used to produce the building blocks of new GFAJ-1 cells.
The central question of the researchers was examined, as the germ was grown on arsenic arsenic has actually made it into the organisms important biochemical machines, such as DNA, proteins, and the cell membranes. A variety of sophisticated laboratory techniques used to determine where the arsenic was incorporated.
The team decided, because of its unusual chemistry, especially its high salinity, high alkalinity and high levels of arsenic to explore Mono Lake. This chemistry results partly from Mono Lake isolation from sources of fresh water for 50 years.
The results of this study will inform ongoing research in many areas, including the study of the Earth evolution, organic chemistry, biogeochemical cycles, disease mitigation and Earth system research. These results also opened new frontiers in microbiology and other areas of research.
"The idea of alternative nutritional analysis for the life in science fiction, joint", said Carl Pilcher, Director of the NASA Astrobiology Institute of agency Ames Research Center in Moffett field, California "until now was a way of life with arsenic as a building block that is only theoretischeaber now we so life knowledge in Mono Lake exists."
The research team included scientists from the United States Geological Survey, Arizona State University in Tempe, Arizona, Lawrence Livermore National Laboratory in Livermore, California, Duquesne University in Pittsburgh, Penn, and the Stanford synchrotron radiation Lightsource in Menlo Park, California.
NASA Astrobiology program in Washington contributed funds for the research on the exobiology and evolutionary biology program and the NASA Astrobiology Institute. NASA Astrobiology program supports research in the origin, development, distribution and future of life on Earth.
Editor: Dr. Tony Phillips | Credit: Science@NASA
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