Felisa Lauren Wolfe-Simon | |
---|---|
Born | Felisa Lauren Wolfe |
Alma mater | Rutgers University Institute of Marine and Coastal Sciences (Ph.D.) Oberlin College (B.A.) Oberlin Conservatory of Music (B.M.) |
Known for | GFAJ-1 bacterium |
Scientific career | |
Fields | Biochemistry Microbiology Astrobiology Geochemistry Geomicrobiology Oceanography |
Institutions | Lawrence Berkeley National Laboratory NASA Astrobiology Institute US Geological Survey Rutgers University |
Felisa Wolfe-Simon is an American microbial geobiologist and biogeochemist. In 2010, Wolfe-Simon led a team that discovered GFAJ-1, an extremophile bacterium that they claimed was capable of substituting arsenic for a small percentage of its phosphorus to sustain its growth, thus advancing the remarkable possibility of non-RNA/DNA-based genetics. [1] However, these conclusions were immediately debated and criticized in correspondence to the original journal of publication, [2] and have since come to be widely disbelieved, though they have never been disputed by any legitimate scientific studies. [3] In 2012, two reports refuting the most significant aspects of the original results were published in the same journal in which the original findings had been previously published. [4] [5]
Wolfe-Simon did her undergraduate studies at Oberlin College and completed a Bachelor of Arts in Biology and Chemistry and a Bachelor of Music in Oboe Performance and Ethnomusicology at the Oberlin Conservatory of Music. [6] She received her Doctor of Philosophy in oceanography from the Institute of Marine and Coastal Sciences at Rutgers University in 2006 with a dissertation titled The Role and Evolution of Superoxide Dismutases in Algae. [7] Later Wolfe-Simon was a NASA research fellow in residence at the US Geological Survey and a member of the NASA Astrobiology Institute.
Wolfe-Simon's research focuses on evolutionary microbiology and exotic metabolic pathways. At a conference in 2008 and subsequent 2009 paper, Wolfe-Simon, Paul Davies and Ariel Anbar proposed that arsenate (AsO3−
4) could serve as a substitute for phosphate (PO3−
4) in various forms of biochemistry. [8] [9] According to Paul Davies, Wolfe-Simon was the one who had the "critical insight" that arsenic might be able to substitute for phosphorus. [10] As late as March 2010, she had been hinting of some shadow biosphere results to the press. [11] [12]
Wolfe-Simon then led a search for such an organism by targeting the naturally occurring arsenic-rich Mono Lake, California. This search led to the discovery of the bacterium GFAJ-1, which her team claimed in a Science on-line article in December 2010 was able to incorporate arsenate as a substitute for a small percentage of the typical phosphate in its DNA and other essential biomolecules. [1] If correct, this would be the only known organism to be capable of replacing phosphorus in its DNA and other vital biochemical functions. [13] [14] [15] The Science publication and an hour-long December 2, 2010 NASA news conference were publicized and led to "wild speculations on the Web about extraterrestrial life". [16] Wolfe-Simon was the only one of the paper's authors at that news conference. [17] The news conference was promptly met with criticism by scientists and journalists. [18] In the following month, Wolfe-Simon (and her co-authors and NASA) responded to criticisms through an online FAQ and an exclusive interview with a Science reporter, but also announced they would not respond further outside scientific peer-review. [19] [20] Wolfe-Simon left USGS in May 2011. [21] Wolfe-Simon maintains she did not leave voluntarily, but was "effectively evicted" from the USGS group. [22]
The Science article "A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus" appeared in the June 3, 2011 print version of Science; [1] it had remained on the "Publication ahead of print" ScienceXpress page for six months after acceptance for publication.
However, Rosemary Redfield and other researchers from the University of British Columbia and Princeton University performed studies in which they used a variety of different techniques to investigate the presence of arsenic in the DNA of GFAJ-1 and published their results in early 2012. The group found no detectable arsenic in the DNA of the bacterium. In addition, they found that arsenate did not help the strain grow when phosphate was limited, further suggesting that arsenate does not replace the role of phosphate. [23] [24]
Following the publication of the articles challenging the conclusions of the original Science article first describing GFAJ-1, the website Retraction Watch argued that the original article should be retracted because of misrepresentation of critical data. [25] [26] As of May 2022, no retraction can be found.
In 2006 Wolfe-Simon was awarded a National Science Foundation Minority Postdoctoral Research Fellowship [27] to support work done at Harvard University and Arizona State University.
Arsenic is a chemical element; it has symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but only the grey form, which has a metallic appearance, is important to industry.
Astrobiology is a scientific field within the life and environmental sciences that studies the origins, early evolution, distribution, and future of life in the universe by investigating its deterministic conditions and contingent events. As a discipline, astrobiology is founded on the premise that life may exist beyond Earth.
Hypothetical types of biochemistry are forms of biochemistry agreed to be scientifically viable but not proven to exist at this time. The kinds of living organisms currently known on Earth all use carbon compounds for basic structural and metabolic functions, water as a solvent, and DNA or RNA to define and control their form. If life exists on other planets or moons it may be chemically similar, though it is also possible that there are organisms with quite different chemistries – for instance, involving other classes of carbon compounds, compounds of another element, or another solvent in place of water.
An extremophile is an organism that is able to live in extreme environments, i.e., environments with conditions approaching or expanding the limits of what known life can adapt to, such as extreme temperature, radiation, salinity, or pH level.
Paul Charles William Davies is an English physicist, writer and broadcaster, a professor in Arizona State University and director of BEYOND: Center for Fundamental Concepts in Science. He is affiliated with the Institute for Quantum Studies in Chapman University in California. He previously held academic appointments in the University of Cambridge, University College London, University of Newcastle upon Tyne, University of Adelaide and Macquarie University. His research interests are in the fields of cosmology, quantum field theory, and astrobiology.
A nanobe is a tiny filamental structure first found in some rocks and sediments. Some scientists hypothesize that nanobes are the smallest form of life, 1/ 10 the size of the smallest known bacteria.
Halomonadaceae is a family of halophilic Pseudomonadota.
The arsenate is an ion with the chemical formula AsO3−4. Bonding in arsenate consists of a central arsenic atom, with oxidation state +5, double bonded to one oxygen atom and single bonded to a further three oxygen atoms. The four oxygen atoms orient around the arsenic atom in a tetrahedral geometry. Resonance disperses the ion's −3 charge across all four oxygen atoms.
The PAH world hypothesis is a speculative hypothesis that proposes that polycyclic aromatic hydrocarbons (PAHs), known to be abundant in the universe, including in comets, and assumed to be abundant in the primordial soup of the early Earth, played a major role in the origin of life by mediating the synthesis of RNA molecules, leading into the RNA world. However, as yet, the hypothesis is untested.
A shadow biosphere is a hypothetical microbial biosphere of Earth that would use radically different biochemical and molecular processes from that of currently known life. Although life on Earth is relatively well studied, if a shadow biosphere exists, it may still remain unnoticed because the exploration of the microbial world targets primarily the biochemistry of the macro-organisms.
PLOS One is a peer-reviewed open access mega journal published by the Public Library of Science (PLOS) since 2006. The journal covers primary research from any discipline within science and medicine. The Public Library of Science began in 2000 with an online petition initiative by Nobel Prize winner Harold Varmus, formerly director of the National Institutes of Health and at that time director of Memorial Sloan–Kettering Cancer Center; Patrick O. Brown, a biochemist at Stanford University; and Michael Eisen, a computational biologist at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory.
Arsenic biochemistry refers to biochemical processes that can use arsenic or its compounds, such as arsenate. Arsenic is a moderately abundant element in Earth's crust, and although many arsenic compounds are often considered highly toxic to most life, a wide variety of organoarsenic compounds are produced biologically and various organic and inorganic arsenic compounds are metabolized by numerous organisms. This pattern is general for other related elements, including selenium, which can exhibit both beneficial and deleterious effects. Arsenic biochemistry has become topical since many toxic arsenic compounds are found in some aquifers, potentially affecting many millions of people via biochemical processes.
GFAJ-1 is a strain of rod-shaped bacteria in the family Halomonadaceae. It is an extremophile that was isolated from the hypersaline and alkaline Mono Lake in eastern California by geobiologist Felisa Wolfe-Simon, a NASA research fellow in residence at the US Geological Survey. In a 2010 Science journal publication, the authors claimed that the microbe, when starved of phosphorus, is capable of substituting arsenic for a small percentage of its phosphorus to sustain its growth. Immediately after publication, other microbiologists and biochemists expressed doubt about this claim, which was robustly criticized in the scientific community. Subsequent independent studies published in 2012 found no detectable arsenate in the DNA of GFAJ-1, refuted the claim, and demonstrated that GFAJ-1 is simply an arsenate-resistant, phosphate-dependent organism.
Dr. Mary A. Voytek is the director of the National Aeronautics and Space Administration (NASA) Astrobiology Program at NASA Headquarters in Washington, D.C. In 2015, Voytek formed Nexus for Exoplanet System Science (NExSS), a systems science initiative by NASA, to search for life on exoplanets. Voytek came to NASA from the U.S. Geological Survey in Reston, VA, where she headed the USGS Microbiology and Molecular Ecology Laboratory from 1998 to 2009.
Arsenate-reducing bacteria are bacteria which reduce arsenates. Arsenate-reducing bacteria are ubiquitous in arsenic-contaminated groundwater (aqueous environment). Arsenates are salts or esters of arsenic acid (H3AsO4), consisting of the ion AsO43−. They are moderate oxidizers that can be reduced to arsenites and to arsine. Arsenate can serve as a respiratory electron acceptor for oxidation of organic substrates and H2S or H2. Arsenates occur naturally in minerals such as adamite, alarsite, legrandite, and erythrite, and as hydrated or anhydrous arsenates. Arsenates are similar to phosphates since arsenic (As) and phosphorus (P) occur in group 15 (or VA) of the periodic table. Unlike phosphates, arsenates are not readily lost from minerals due to weathering. They are the predominant form of inorganic arsenic in aqueous aerobic environments. On the other hand, arsenite is more common in anaerobic environments, more mobile, and more toxic than arsenate. Arsenite is 25–60 times more toxic and more mobile than arsenate under most environmental conditions. Arsenate can lead to poisoning, since it can replace inorganic phosphate in the glyceraldehyde-3-phosphate --> 1,3-biphosphoglycerate step of glycolysis, producing 1-arseno-3-phosphoglycerate instead. Although glycolysis continues, 1 ATP molecule is lost. Thus, arsenate is toxic due to its ability to uncouple glycolysis. Arsenate can also inhibit pyruvate conversion into acetyl-CoA, thereby blocking the TCA cycle, resulting in additional loss of ATP.
Julia A. Vorholt is a full professor of microbiology at ETH Zurich and an elected member of the German Academy of Sciences Leopoldina.
Rosemary Jeanne Redfield is a microbiologist associated with the University of British Columbia where she worked as a faculty member in the Department of Zoology from 1993 until retiring in 2021.
Hachimoji DNA is a synthetic nucleic acid analog that uses four synthetic nucleotides in addition to the four present in the natural nucleic acids, DNA and RNA. This leads to four allowed base pairs: two unnatural base pairs formed by the synthetic nucleobases in addition to the two normal pairs. Hachimoji bases have been demonstrated in both DNA and RNA analogs, using deoxyribose and ribose respectively as the backbone sugar.
Ariel Anbar is an isotope geochemist and President's Professor at Arizona State University. He has published over 180 refereed papers on topics ranging from the origins of Earth's atmosphere to detecting life on other worlds to diagnosing human disease.
Ronald Oremland was an American microbiologist, astrobiologist, and emeritus senior scientist at the United States Geological Survey. He authored over 200 papers on the microbiology of extreme habitats.