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A 2010 paper in [[Science (journal)|Science]] <ref name="Wolfe-Simon">{{cite journal |last=Wolfe-Simon |first=Felisa |last2=Blum |first2=Jodi Switzer |last3=Kulp |first3=Thomas R. |last4=Gordon |first4=Gwyneth W. |last5=Hoeft |first4=Shelley E. |last6=Pett-Ridge |first6=Jennifer |last7=Stolz |first7=John F. |last8=Webb |first8=Samuel M. |last9=Weber |first9=Peter K. |last10=Davis |first10=Paul C. W. |last11=Anbar |first11=Ariel D. |last13=Oremland |first13=Ronald S. |title=A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus |journal=[[Science (journal)|Science]] |date=2 December 2010 |doi=10.1126/science.1197258 |pmid=21127214 |url=http://www.sciencemag.org/content/early/2010/12/01/science.1197258 |accessdate=2010-12-06}}</ref> reports that [[GFAJ-1]] is facultatively capable of incorporating [[arsenate]] into its DNA under conditions of phosphorus starvation. [[NASA]] announced at a [[press conference]] on 2 December 2010 the discovery of an [[organism]] dubbed GFAJ-1 [[Felisa Wolfe-Simon]] by a team lead by that has been proposed to utilize arsenic in its cellular structure. GFAJ stands for "Give Felisa A Job". During the press conference, the implications to [[astrobiology]] were emphasized. If this proposal is verified, it would constitute the first discovery of a [[life form]] capable of replacing one of the primary six chemical elements in its makeup, namely: [[carbon]], [[hydrogen]], [[oxygen]], [[nitrogen]], [[phosphorus]] and [[sulfur]] (or "[[CHONPS]]" for short).<ref>{{cite news |title=Arsenic-loving bacteria may help in hunt for alien life |last=Palmer |first=Jason |publisher=[[BBC News]] |date=2 December 2010 |accessdate=2010-12-02 |url=http://www.bbc.co.uk/news/science-environment-11886943 }}</ref><ref>{{cite web |title=NASA news conference participants |last=Kottke |first=Jason |publisher=[[Kottke.org]] |date=29 November 2010 |accessdate=2010-12-02 |url=http://kottke.org/10/11/has-nasa-discovered-extraterrestrial-life }}</ref><ref name="nature">{{cite web |title=Arsenic-eating microbe may redefine chemistry of life |first=Alla |last=Katsnelson |publisher=[[Nature News]] |date=2 December 2010 |accessdate=2010-12-02 |url=http://www.nature.com/news/2010/101202/full/news.2010.645.html |doi=10.1038/news.2010.645}}</ref><ref>[http://www.astrobio.net/index.php?option=com_expedition&task=detail&id=3259 NASA - Astrobiology Magazine: "Searching for Alien Life, on Earth"] October 2009</ref><ref name="nasa">{{cite web |title=Searching for Alien Life, on Earth |last=Bortman |first=Henry |publisher=Astrobiology Magazine (NASA) |date=5 October 2009 |accessdate=2010-12-02 |url=http://www.astrobio.net/index.php?option=com_expedition&task=detail&id=3259}}</ref><ref>{{cite news |title=Could the Mono Lake arsenic prove there is a shadow biosphere? |first=Mike |last=Harvey |publisher=[[The Times]] |location=UK |date=4 March 2010 |accessdate=2010-12-02 |url=http://www.timesonline.co.uk/tol/news/science/eureka/article7040864.ece }}</ref>
A 2010 paper in [[Science (journal)|Science]] <ref name="Wolfe-Simon">{{cite journal |last=Wolfe-Simon |first=Felisa |last2=Blum |first2=Jodi Switzer |last3=Kulp |first3=Thomas R. |last4=Gordon |first4=Gwyneth W. |last5=Hoeft |first4=Shelley E. |last6=Pett-Ridge |first6=Jennifer |last7=Stolz |first7=John F. |last8=Webb |first8=Samuel M. |last9=Weber |first9=Peter K. |last10=Davis |first10=Paul C. W. |last11=Anbar |first11=Ariel D. |last13=Oremland |first13=Ronald S. |title=A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus |journal=[[Science (journal)|Science]] |date=2 December 2010 |doi=10.1126/science.1197258 |pmid=21127214 |url=http://www.sciencemag.org/content/early/2010/12/01/science.1197258 |accessdate=2010-12-06}}</ref> reports that [[GFAJ-1]] is facultatively capable of incorporating [[arsenate]] into its DNA under conditions of phosphorus starvation. [[NASA]] announced at a [[press conference]] on 2 December 2010 the discovery of an [[organism]] dubbed GFAJ-1 [[Felisa Wolfe-Simon]] by a team lead by that has been proposed to utilize arsenic in its cellular structure. GFAJ stands for "Give Felisa A Job". During the press conference, the implications to [[astrobiology]] were emphasized. If this proposal is verified, it would constitute the first discovery of a [[life form]] capable of replacing one of the primary six chemical elements in its makeup, namely: [[carbon]], [[hydrogen]], [[oxygen]], [[nitrogen]], [[phosphorus]] and [[sulfur]] (or "[[CHONPS]]" for short).<ref>{{cite news |title=Arsenic-loving bacteria may help in hunt for alien life |last=Palmer |first=Jason |publisher=[[BBC News]] |date=2 December 2010 |accessdate=2010-12-02 |url=http://www.bbc.co.uk/news/science-environment-11886943 }}</ref><ref>{{cite web |title=NASA news conference participants |last=Kottke |first=Jason |publisher=[[Kottke.org]] |date=29 November 2010 |accessdate=2010-12-02 |url=http://kottke.org/10/11/has-nasa-discovered-extraterrestrial-life }}</ref><ref name="nature">{{cite web |title=Arsenic-eating microbe may redefine chemistry of life |first=Alla |last=Katsnelson |publisher=[[Nature News]] |date=2 December 2010 |accessdate=2010-12-02 |url=http://www.nature.com/news/2010/101202/full/news.2010.645.html |doi=10.1038/news.2010.645}}</ref><ref>[http://www.astrobio.net/index.php?option=com_expedition&task=detail&id=3259 NASA - Astrobiology Magazine: "Searching for Alien Life, on Earth"] October 2009</ref><ref name="nasa">{{cite web |title=Searching for Alien Life, on Earth |last=Bortman |first=Henry |publisher=Astrobiology Magazine (NASA) |date=5 October 2009 |accessdate=2010-12-02 |url=http://www.astrobio.net/index.php?option=com_expedition&task=detail&id=3259}}</ref><ref>{{cite news |title=Could the Mono Lake arsenic prove there is a shadow biosphere? |first=Mike |last=Harvey |publisher=[[The Times]] |location=UK |date=4 March 2010 |accessdate=2010-12-02 |url=http://www.timesonline.co.uk/tol/news/science/eureka/article7040864.ece }}</ref>


[[Arsenic]], which is chemically similar to [[phosphorus]], while poisonous for most Earth life, is incorporated into the biochemistry of some organisms.<ref>{{cite web|url=http://umbbd.msi.umn.edu/periodic/elements/as.html |title=Biochemical Periodic Table - Arsenic |publisher=Umbbd.msi.umn.edu |date=2007-06-08 |accessdate=2010-05-29}}</ref> Some marine algae incorporate arsenic into complex organic molecules such as [[arsenosugar]]s and [[arsenobetaine]]s. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes (''[[Chrysiogenes arsenatis]]'').<ref>{{cite journal| journal= Appl Environ Microbiol| year= 2001| month= December| volume=67| issue=12| pages=5568–80| title= Isolation and characterization of a novel As(V)-reducing bacterium: implications for arsenic mobilization and the genus Desulfitobacterium| last= Niggemyer| first= A| coauthors= Spring S, Stackebrandt E, Rosenzweig RF| doi=10.1128/AEM.67.12.5568-5580.2001| pmid= 11722908| pmc= 93345}}</ref> Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy. In the context of of astrobiology, it has been speculated that the earliest life on Earth may have used arsenic in place of phosphorus in the backbone of its DNA.<ref>{{cite journal |url=http://www.newscientist.com/channel/life/mg19826533.600-early-life-could-have-relied-on-arsenic-dna.html |journal=New Scientist |title= Early life could have relied on 'arsenic DNA' |date=26 April 2008 |first=Michael |last=Reilly |issue=2653 |doi=10.1016/S0262-4079(08)61007-6 |volume=198 |page=10}}</ref> A [[geomicrobiology]] study released by NASA has revealed that a bacterium named [[GFAJ-1]], collected in the sediments of [[Mono Lake]] in eastern [[California]], appears to employ such '[[Arsenic#Arsenic reported substituting for phosphorus as a building block of life|arseno-DNA]]' when cultured in very low concentrations of phosphorus.<ref name="nasafund">{{cite web |title=NASA-Funded Research Discovers Life Built With Toxic Chemical |publisher=NASA.gov |date=2 December 2010 |accessdate=2010-12-02 |url=http://www.nasa.gov/topics/universe/features/astrobiology_toxic_chemical.html}}</ref><ref name="nature">{{cite web |title=Arsenic-eating microbe may redefine chemistry of life |first=Alla |last=Katsnelson |publisher=Nature News |date=2 December 2010 |accessdate=2010-12-02 |url=http://www.nature.com/news/2010/101202/full/news.2010.645.html |doi=10.1038/news.2010.645}}</ref><ref name="Thriving">{{cite news|title=Thriving on Arsenic, a Microbe May Redefine Life|newspaper=New York Times|date=December 2, 2010|author=Dennis Overbye|url=http://www.nytimes.com/2010/12/03/science/03arsenic.htm}}</ref>
[[Arsenic]], which is chemically similar to [[phosphorus]], while poisonous for most Earth life, is incorporated into the biochemistry of some organisms.<ref>{{cite web|url=http://umbbd.msi.umn.edu/periodic/elements/as.html |title=Biochemical Periodic Table - Arsenic |publisher=Umbbd.msi.umn.edu |date=2007-06-08 |accessdate=2010-05-29}}</ref> Some marine algae incorporate arsenic into complex organic molecules such as [[arsenosugar]]s and [[arsenobetaine]]s. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes (''[[Chrysiogenes arsenatis]]'').<ref>{{cite journal| journal= Appl Environ Microbiol| year= 2001| month= December| volume=67| issue=12| pages=5568–80| title= Isolation and characterization of a novel As(V)-reducing bacterium: implications for arsenic mobilization and the genus Desulfitobacterium| last= Niggemyer| first= A| coauthors= Spring S, Stackebrandt E, Rosenzweig RF| doi=10.1128/AEM.67.12.5568-5580.2001| pmid= 11722908| pmc= 93345}}</ref> Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy. In the context of of astrobiology, it has been speculated that the earliest life on Earth may have used arsenic in place of phosphorus in the backbone of its DNA.<ref>{{cite journal |url=http://www.newscientist.com/channel/life/mg19826533.600-early-life-could-have-relied-on-arsenic-dna.html |journal=New Scientist |title= Early life could have relied on 'arsenic DNA' |date=26 April 2008 |first=Michael |last=Reilly |issue=2653 |doi=10.1016/S0262-4079(08)61007-6 |volume=198 |page=10}}</ref><ref name="nasafund">{{cite web |title=NASA-Funded Research Discovers Life Built With Toxic Chemical |publisher=NASA.gov |date=2 December 2010 |accessdate=2010-12-02 |url=http://www.nasa.gov/topics/universe/features/astrobiology_toxic_chemical.html}}</ref><ref name="Thriving">{{cite news|title=Thriving on Arsenic, a Microbe May Redefine Life|newspaper=New York Times|date=December 2, 2010|author=Dennis Overbye|url=http://www.nytimes.com/2010/12/03/science/03arsenic.htm}}</ref>


==Criticism==
==Criticism==

Revision as of 10:46, 9 December 2010

Arseno-DNA refers to a hypothetical DNA analog in which arsenate partially or fully replaces phosphate present in its backbone. This analog has been proposed to be sustainable in vivo in GFAJ-1 bacteria.

Further information: GFAJ-1

A 2010 paper in Science [1] reports that GFAJ-1 is facultatively capable of incorporating arsenate into its DNA under conditions of phosphorus starvation. NASA announced at a press conference on 2 December 2010 the discovery of an organism dubbed GFAJ-1 Felisa Wolfe-Simon by a team lead by that has been proposed to utilize arsenic in its cellular structure. GFAJ stands for "Give Felisa A Job". During the press conference, the implications to astrobiology were emphasized. If this proposal is verified, it would constitute the first discovery of a life form capable of replacing one of the primary six chemical elements in its makeup, namely: carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur (or "CHONPS" for short).[2][3][4][5][6][7]

Arsenic, which is chemically similar to phosphorus, while poisonous for most Earth life, is incorporated into the biochemistry of some organisms.[8] Some marine algae incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines. Fungi and bacteria can produce volatile methylated arsenic compounds. Arsenate reduction and arsenite oxidation have been observed in microbes (Chrysiogenes arsenatis).[9] Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and some can utilize arsenite as an electron donor to generate energy. In the context of of astrobiology, it has been speculated that the earliest life on Earth may have used arsenic in place of phosphorus in the backbone of its DNA.[10][11][12]

Criticism

At a NASA press conference to announce Wolfe-Simon's results, Steven A. Benner expressed some skepticism that arsenate was substituted in for phosphate in the DNA backbone of these organisms unless other new mechanisms were present in the organism to prevent hydrolysis of the arsenate ester chemical bonds.[13] If the proposal is correct that bacterium GFAJ-1 uses arsenate in its DNA and other biomolecules, then it must have found a way to stabilize arsenate esters or otherwise work around this limitation. Wolfe-Simon speculates that this stability might be accomplished in part by isolating some arsenate containing molecules in large vacuole compartments rich in poly-β-hydroxybutyrate that GFAJ-1 develops when cultured in arsenic but not when cultured in phosphorus.[14]

Other scientists have expressed their skepticism;[13] microbiologists Rosemary Redfield[15] and, separately, Athena Andreadis[16] have suggested the claims could potentially be based on errors in how the research studies were conducted. Several other chemists, including Nicholas Winograd, Keith Hodgson, Gerald Joyce, Ronald S. Oremland and John D. Sutherland have come out suggesting that the announcement was premature.[17][18]

See also

References

  1. ^ Wolfe-Simon, Felisa; Blum, Jodi Switzer; Kulp, Thomas R.; Gordon, Shelley E.; Hoeft; Pett-Ridge, Jennifer; Stolz, John F.; Webb, Samuel M.; Weber, Peter K.; Davis, Paul C. W.; Anbar, Ariel D.; Oremland, Ronald S. (2 December 2010). "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus". Science. doi:10.1126/science.1197258. PMID 21127214. Retrieved 2010-12-06. {{cite journal}}: Missing |author12= (help)
  2. ^ Palmer, Jason (2 December 2010). "Arsenic-loving bacteria may help in hunt for alien life". BBC News. Retrieved 2010-12-02.
  3. ^ Kottke, Jason (29 November 2010). "NASA news conference participants". Kottke.org. Retrieved 2010-12-02.
  4. ^ Katsnelson, Alla (2 December 2010). "Arsenic-eating microbe may redefine chemistry of life". Nature News. doi:10.1038/news.2010.645. Retrieved 2010-12-02.
  5. ^ NASA - Astrobiology Magazine: "Searching for Alien Life, on Earth" October 2009
  6. ^ Bortman, Henry (5 October 2009). "Searching for Alien Life, on Earth". Astrobiology Magazine (NASA). Retrieved 2010-12-02.
  7. ^ Harvey, Mike (4 March 2010). "Could the Mono Lake arsenic prove there is a shadow biosphere?". UK: The Times. Retrieved 2010-12-02.
  8. ^ "Biochemical Periodic Table - Arsenic". Umbbd.msi.umn.edu. 2007-06-08. Retrieved 2010-05-29.
  9. ^ Niggemyer, A (2001). "Isolation and characterization of a novel As(V)-reducing bacterium: implications for arsenic mobilization and the genus Desulfitobacterium". Appl Environ Microbiol. 67 (12): 5568–80. doi:10.1128/AEM.67.12.5568-5580.2001. PMC 93345. PMID 11722908. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  10. ^ Reilly, Michael (26 April 2008). "Early life could have relied on 'arsenic DNA'". New Scientist. 198 (2653): 10. doi:10.1016/S0262-4079(08)61007-6.
  11. ^ "NASA-Funded Research Discovers Life Built With Toxic Chemical". NASA.gov. 2 December 2010. Retrieved 2010-12-02.
  12. ^ Dennis Overbye (December 2, 2010). "Thriving on Arsenic, a Microbe May Redefine Life". New York Times.
  13. ^ a b Bortman, Henry (2010-12-02). "Arsenic-Eating Bacteria Opens New Possibilities for Alien Life". Space.Com web site. Retrieved 2010-12-02. {{cite web}}: External link in |work= (help) Alt URL Cite error: The named reference "Bortman" was defined multiple times with different content (see the help page).
  14. ^ Wolfe-Simon F; et al. (2010-12-02). "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus". Science. doi:10.1126/science.1197258. {{cite journal}}: Explicit use of et al. in: |author= (help)
  15. ^ Redfield, Rosemary J. (4 December 2010). "Arsenic-associated bacteria (NASA's claims)". RR Research blog. Retrieved 2010-12-06. {{cite web}}: External link in |work= (help)
  16. ^ Andreadis, Athena (3 December 2010). "Arsenic and Odd Lace". The Huffington Post. The Huffington Post. Retrieved 2010-12-08. {{cite web}}: External link in |work= (help)
  17. ^ Arsenic Bacteria Breed Backlash: Controversy: Claim that microbe weaves arsenic into its DNA comes under fire December 8, 2010
  18. ^ "This Paper Should Not Have Been Published": Scientists see fatal flaws in the NASA study of arsenic-based life. by Carl Zimmer, Slate.com, Dec. 7, 2010
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