NASA-Funded Research Discovers Life Built With Toxic Chemical

[嵐月銀牙 10]

http://www.nasa.gov/topics/universe/features/astrobiology_toxic_chemical.html

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NASA-Funded Research Discovers Life Built With Toxic Chemical

NASA研究發現以有毒化學物質組成的生命

NASA-funded astrobiology research has changed the fundamental knowledge about what comprises all known life on Earth.

NASA的天體生物學家的研究改變了我們對地球上已知生物的基礎知識。

Researchers conducting tests in the harsh environment of Mono Lake in California have discovered the first known microorganism on Earth able to thrive and reproduce using the toxic chemical arsenic. The microorganism substitutes arsenic for phosphorus in its cell components.

研究人員在加州的Mono湖中發現了地球上已知最早能使用有毒化學物質"砷"的微生物，這些微生物利用砷來代替磷的功能。

"The definition of life has just expanded," said Ed Weiler, NASA's associate administrator for the Science Mission Directorate at the agency's Headquarters in Washington. "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."

"生命的定義才剛開始展開。"NASA在華盛頓的總部科學任務理事會的副管理員，Ed Weiler說道，“作為我們追求努力尋求太陽系中的生命跡象，我們必須考慮更廣泛，更多元化以及我們所不知道的生命形態。”

This finding of an alternative biochemistry makeup will alter biology textbooks and expand the scope of the search for life beyond Earth. The research is published in this week's edition of Science Express.

這另一種生物化學結構的發現將改變生物教科書的範圍，擴大了尋找地球以外生命的範圍。這項研究將在本週的版Science表達。

Carbon, hydrogen, nitrogen, oxygen, 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 considered an essential element for all living cells.

碳，氫，氮，氧，磷和硫是在地球上所有已知的生命形式的六個基本構成元素。磷是化學骨幹的一部分，DNA和RNA的結構進行遺傳指令，被認為是所有活細胞必不可少的元素。

Phosphorus is a central component of the energy-carrying molecule in all cells (adenosine triphosphate) and also the phospholipids that form all cell membranes. Arsenic, which is chemically similar to phosphorus, is poisonous for most life on Earth. Arsenic disrupts metabolic pathways because chemically it behaves similarly to phosphate.

磷是在所有細胞核心組成的一種能量攜帶分子(三磷酸腺苷)，也構成所有磷脂細胞膜。砷，這是化學性質類似於磷，大多數以有毒物質的方式存在在地球上。砷會擾亂代謝途徑，因為它的行為類似於化學磷肥。

"We know that some microbes can breathe arsenic, but what we've found is a microbe doing something new -- building parts of itself out of arsenic," said Felisa Wolfe-Simon, a NASA Astrobiology Research Fellow in residence at the U.S. Geological Survey in Menlo Park, Calif., and the research team's lead scientist. "If something here on Earth can do something so unexpected, what else can life do that we haven't seen yet?"

“我們知道，某些微生物能呼吸砷，但現在我們發現的只是一種微生物做新的東西 - 結構部分自行解決砷，”沃爾夫說Felisa Wolfe-Simon，一個居住在門洛帕克市的美國宇航局天體生物學研究員，美國地質調查局研究小組的首席科學家。 “如果對地球上生命可以做的一些事情感到如此意外，那那些生命可以做而我們還沒有看到怎麼辦？"

The newly discovered microbe, strain GFAJ-1, is a member of a common group of bacteria, the Gammaproteobacteria. In the laboratory, the researchers successfully grew microbes from the lake on a diet that was very lean on phosphorus, but included generous helpings of arsenic. When researchers removed the phosphorus and replaced it with arsenic the microbes continued to grow. Subsequent analyses indicated that the arsenic was being used to produce the building blocks of new GFAJ-1 cells.

新發現的微生物，GFAJ - 1品系，是一個常見的細菌界成員，Gammaproteobacteria。在實驗室裡，研究人員成功地讓湖中微生物生長在一個缺乏磷但是富含砷的環境中。當研究人員除去了磷，砷取代它的位置讓微生物繼續增長。隨後的分析表明，砷被用來生產新的GFAJ - 1細胞。

The key issue the researchers investigated was when the microbe was grown on arsenic did the arsenic actually became incorporated into the organisms' vital biochemical machinery, such as DNA, proteins and the cell membranes. A variety of sophisticated laboratory techniques was used to determine where the arsenic was incorporated.

問題的關鍵是，當研究人員調查了那些長在砒霜上的微生物，砷實際上納入生物的重要生化機械，如DNA，蛋白質和細胞膜。各種先進的實驗室技術被用來確定砷在何處併入。

The team chose to explore Mono Lake because of its unusual chemistry, especially its high salinity, high alkalinity, and high levels of arsenic. This chemistry is in part a result of Mono Lake's isolation from its sources of fresh water for 50 years.

研究小組選擇了探索Mono湖，因為它不尋常的化學成分。特別是它的高鹽度，高鹼度，高濃度的砷。這化學結果在很大程度上是因為Mono湖與淡水水源隔離了50年。

The results of this study will inform ongoing research in many areas, including the study of Earth's evolution, organic chemistry, biogeochemical cycles, disease mitigation and Earth system research. These findings also will open up new frontiers in microbiology and other areas of research.

這項研究結果將影響許多領域正在進行的研究，包括研究地球的演變，有機化工，生物地球化學循環，疾病緩解和地球系統的研究。這些結果也將開闢新領域和其他領域中的微生物學研究。

"The idea of alternative biochemistries for life is common in science fiction," said Carl Pilcher, director of the NASA Astrobiology Institute at the agency's Ames Research Center in Moffett Field, Calif. "Until now a life form using arsenic as a building block was only theoretical, but now we know such life exists in Mono Lake."

“我們認為不同於一般生物化學的生命體是科幻小說的情節。"Moffett Field的Ames研究中心在NASA天體生物學研究所主任，Carl Pilcher說道。“到現在為止的生命形式以砷作為構建塊只有理論，但現在我們知道這樣的生命存在Mono湖中“。

The research team included scientists from the U.S. Geological Survey, Arizona State University in Tempe, Ariz., Lawrence Livermore National Laboratory in Livermore, Calif., Duquesne University in Pittsburgh, Penn., and the Stanford Synchroton Radiation Lightsource in Menlo Park, Calif.

該研究小組的科學家包括來自美國地質調查局，亞利桑那州立大學 亞利桑那州 勞倫斯利弗莫爾國家實驗室的 Livermore，加利福尼亞州 匹茲堡的 杜肯大學，賓夕法尼亞大學，和加州的Menlo Park史丹佛大學Synchroton Radiation Lightsource。

NASA's Astrobiology Program in Washington contributed funding for the research through its Exobiology and Evolutionary Biology program and the NASA Astrobiology Institute. NASA's Astrobiology Program supports research into the origin, evolution, distribution, and future of life on Earth.

NASA天體生物學計劃在華盛頓通過捐助NASA天體生物學研究所資金供其研究其宇宙生物學和進化生物學計劃，NASA的天體生物學研究計劃支持的起源，演化，分佈和地球上生命的未來。

For more information about the finding and a complete list of researchers, visit:

http://astrobiology.nasa.gov/

Image of Mono Lake Research area

Felisa Wolfe-Simon processing mud from Mono Lake to inoculate media to grow microbes on arsenic.

Image of GFAJ-1 grown on arsenic.

Image Credit: Jodi Switzer Blum

Image Credit: Henry Bortman

Image of GFAJ-1 grown on phosphorus.

Image Credit: Jodi Switzer Blum