Arsenic Based Life, NASA

December 2, 2010 by USA Post 

Arsenic Based Life, In a study that could rewrite biology textbooks, the scientists found the first known living organism that incorporates arsenic into the functioning of its cells. Moreover, arsenic replaces phosphorus, an element long believed essential to life. The results, based on experiments at the Stanford Synchrotron Radiation Light Source, were published online today in Science Express.

“It seems that this particular strain of bacteria has actually changed in a way that it can use arsenic instead of phosphorus to grow and produce life,” said SSRL staff scientist Sam Webb, who led the research Department of Energy SLAC National Accelerator Laboratory. “Given that arsenic is generally toxic, this finding is particularly surprising.”

Phosphorus is part of the chemical backbone of DNA and RNA, the spiral structures that carry genetic instructions for life. There is also a central element of the ATP, which carries the chemical energy necessary for metabolism in cells. Scientists have for decades thought life could not survive without it.

But this was not the case for a strain of bacteria called Halomonadaceae GFAJ-1, discovered in a lake east of California. The colonies of these bacteria thrived, as expected, when given a steady supply of phosphorus and other necessities, yet when the researchers replaced the phosphorus with arsenic, the colony continued to grow.

This suggested Felisa Wolfe-Simon, a researcher at NASA and geobiologist in residence with the U.S. Geological Survey, the bacteria were using arsenic instead of phosphorus.

“We already knew that other microbes can ‘breathe arsenic, but it seemed these bacteria could be something new construction elements themselves to arsenic,” said Wolfe-Simon, author senior newspaper. “To see if this were the case, we brought samples of SSRL. I came armed with the knowledge that bacteria did something really strange and I knew SSRL beamline 2-3, in the hands of Sam, we could say more. ”

Wolfe-Simon general objective was to see whether arsenic has been closely associated with bacterial cells or simply attached to the outside. The team swept the SSRL beam X-ray thin hair through a sample of bacteria that were bathed in high concentrations of arsenic. The interaction between X-rays and the sample showed where and how arsenic wound inside bacterial cells.

“We saw similarities in the distribution of arsenic and the distribution of iron and zinc, two metals which show where cellular material of an organism is located, said Wolfe-Simon. However, the distribution of phosphorus did not match the distribution of other elements, suggesting that arsenic has taken the place of phosphorus in the cell material of the bacterium.

To confirm this suspicion, the team conducted another experiment with the SSRL beam, this time in a spectroscopic mode, which identifies the types and locations of specific atoms. Experience has shown that nearest neighbor arsenic atoms are oxygen and, at distances a little longer, carbon. This trend and the precise distances between the three types of atoms are a nearly perfect match with the phosphorus atoms and bind to other atoms of the DNA strands classic.

Wolfe-Simon said that these experiments strongly suggest that bacteria are not only absorb arsenic, but by integrating it into their beings as “organic arsenic.”

Further reinforce this point of view, arsenic has not taken the form that would be the case if, for example, one organization has been trying to remove the toxin from their system, and it was not surrounded by types of molecules that the body can use to make the inert arsenic, Webb said. The fact that he was attached to carbon and oxygen, he said, is “what we expect if he were actually used to create DNA, RNA or protein.” It would strain GFAJ-1 bacteria the first organism known to use arsenic instead of phosphorus for growth.

“In theory, this knowledge will rewrite biology textbooks,” said Wolfe-Simon. “Whenever you hear about” diversity “in biology, it is always the metabolic diversity of diversity in organizations that they oxidize or breathe how they earn their living. However, it is assumed that various agencies can be, they are all the same elements: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur this type of bacteria is not and that suggest that there may be a whole new world to explore organizations’…

Then, the team plans to study the specific ways these bacteria can use arsenic in proteins, lipids and nucleic acids like DNA.

“To do this, we need a larger sample,” said Webb. “Felisa and her team work to grow now, and we look forward to continue to study the details of this organization SSRL surprising.”

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This research was conducted by Felisa Wolfe-Simon (NASA Astrobiology Institute, U.S. Geological Survey), Jodi Blum Switzerland (USGS), Thomas R. Kulp (U.S. Geological Survey), Gwyneth W. Gordon (Arizona State University), Shelley E. Hoeft (U.S. Geological Survey), Jennifer Pett-Ridge (Lawrence Livermore National Laboratory), John F. Stolz (Duquesne University), Samuel M. Webb (SSRL and SLAC), Peter K. Weber (Lawrence Livermore National Laboratory), Paul CW Davies (Astrobiology Institute of NASA, Arizona State University), Ariel D. Anbar (Astrobiology Institute of NASA, Arizona State University) and Ronald S. Oremland (U.S. Geological Survey).

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