Meytal B. Higgins, Felisa Wolfe‐Simon, Rebecca S. Robinson, Yelun Qin, Mak A. Saito, Ann Pearson,
Tópico(s): Geology and Paleoclimatology Research
2011 - Elsevier BV | Geochimica et Cosmochimica Acta
Felisa Wolfe‐Simon, Jodi Switzer Blum, Thomas R. Kulp, Gwyneth W. Gordon, Shelley E. Hoeft, Jennifer Pett‐Ridge, John F. Stolz, Samuel M. Webb, Peter Weber, Paul Davies, Ariel D. Anbar, Ronald S. Oremland,
Concerns have been raised about our recent study suggesting that arsenic (As) substitutes for phosphorus in major biomolecules of a bacterium that tolerates extreme As concentrations. We welcome the opportunity to better explain our methods and results and to consider alternative interpretations. We maintain that our interpretation of As substitution, based on multiple congruent lines of evidence, is viable.
Tópico(s): Porphyrin Metabolism and Disorders
2011 - American Association for the Advancement of Science | Science
Jennifer B. Glass, Felisa Wolfe‐Simon, James J. Elser, Ariel D. Anbar,
Molybdenum (Mo) is essential for the biological assimilation of inorganic nitrogen (N). We compared Mo requirements for N 2 ‐fixation in two species of filamentous heterocystous cyanobacteria (HC) to test the hypothesis that coastal HC require higher Mo concentrations than freshwater HC. This expectation follows from the fact that Mo is more concentrated in seawater (~ 105 nmol L −1 ) than in most freshwaters (< 20 nmol L −1 ). Contrary to this hypothesis, we found that both strains maintained N 2 ‐fixation for 30 ...
Tópico(s): Marine and coastal ecosystems
2010 - Wiley | Limnology and Oceanography
Devendra Kumar Chauhan, I. Mihaela Folea, Craig C. Jolley, Roman Kouřil, Carolyn E. Lubner, Su Lin, Dorota Kolber, Felisa Wolfe‐Simon, John H. Golbeck, Egbert J. Boekema, Petra Fromme,
Iron (Fe) availability is a major limiting factor for primary production in aquatic environments. Cyanobacteria respond to Fe deficiency by derepressing the isiAB operon, which encodes the antenna protein IsiA and flavodoxin. At nanomolar Fe concentrations, a PSI-IsiA supercomplex forms, comprising a PSI trimer encircled by two complete IsiA rings. This PSI-IsiA supercomplex is the largest photosynthetic membrane protein complex yet isolated. This study presents a detailed characterization of this ...
Tópico(s): Geochemistry and Elemental Analysis
2010 - American Chemical Society | Biochemistry
Jennifer B. Glass, Felisa Wolfe‐Simon, James J. Elser, Ariel D. Anbar,
Tópico(s): Aquatic Ecosystems and Phytoplankton Dynamics
2010 - Wiley | Limnology and Oceanography
Felisa Wolfe‐Simon, Jodi Switzer Blum, Thomas R. Kulp, Gwyneth W. Gordon, Shelley E. Hoeft, Jennifer Pett‐Ridge, John F. Stolz, Samuel M. Webb, Peter Weber, Paul Davies, Ariel D. Anbar, Ronald S. Oremland,
Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur, and phosphorus. Although these six elements make up nucleic acids, proteins, and lipids and thus the bulk of living matter, it is theoretically possible that some other elements in the periodic table could serve the same functions. Here, we describe a bacterium, strain GFAJ-1 of the Halomonadaceae, isolated from Mono Lake, California, that is able to substitute arsenic for phosphorus to sustain its growth. Our data ...
Tópico(s): Chromium effects and bioremediation
2010 - American Association for the Advancement of Science | Science
Ronald S. Oremland, Chad W. Saltikov, Felisa Wolfe‐Simon, John F. Stolz,
Abstract If you were asked to speculate about the form extra-terrestrial life on Mars might take, which geomicrobial phenomenon might you select as a model system, assuming that life on Mars would be 'primitive'? Give your reasons. At the end of my senior year at Rensselaer Polytechnic Institute in 1968, I took Professor Ehrlich's final for his Geomicrobiology course. The above question beckoned to me like the Sirens to Odysseus, for if I answered, it would take so much time and thought that I would ...
Tópico(s): Polar Research and Ecology
2009 - Taylor & Francis | Geomicrobiology Journal
David T. Johnston, Felisa Wolfe‐Simon, Ann Pearson, Andrew H. Knoll,
Molecular oxygen (O(2)) began to accumulate in the atmosphere and surface ocean ca. 2,400 million years ago (Ma), but the persistent oxygenation of water masses throughout the oceans developed much later, perhaps beginning as recently as 580-550 Ma. For much of the intervening interval, moderately oxic surface waters lay above an oxygen minimum zone (OMZ) that tended toward euxinia (anoxic and sulfidic). Here we illustrate how contributions to primary production by anoxygenic photoautotrophs (including ...
Tópico(s): Geochemistry and Elemental Analysis
2009 - National Academy of Sciences | Proceedings of the National Academy of Sciences
Paul Davies, Steven A. Benner, Carol E. Cleland, Charles H. Lineweaver, Christopher P. McKay, Felisa Wolfe‐Simon,
Astrobiologists are aware that extraterrestrial life might differ from known life, and considerable thought has been given to possible signatures associated with weird forms of life on other planets. So far, however, very little attention has been paid to the possibility that our own planet might also host communities of weird life. If life arises readily in Earth-like conditions, as many astrobiologists contend, then it may well have formed many times on Earth itself, which raises the question ...
Tópico(s): Methane Hydrates and Related Phenomena
2009 - Mary Ann Liebert, Inc. | Astrobiology
Jennifer B. Glass, Felisa Wolfe‐Simon, Ariel D. Anbar,
Abstract Marine primary producers adapted over eons to the changing chemistry of the oceans. Because a number of metalloenzymes are necessary for N assimilation, changes in the availability of transition metals posed a particular challenge to the supply of this critical nutrient that regulates marine biomass and productivity. Integrating recently developed geochemical, biochemical, and genetic evidence, we infer that the use of metals in N assimilation – particularly Fe and Mo – can be understood in ...
Tópico(s): Marine and coastal ecosystems
2009 - Wiley | Geobiology
Felisa Wolfe‐Simon, Paul Davies, Ariel D. Anbar,
Abstract All known life requires phosphorus (P) in the form of inorganic phosphate (PO 4 3− or P i ) and phosphate-containing organic molecules. P i serves as the backbone of the nucleic acids that constitute genetic material and as the major repository of chemical energy for metabolism in polyphosphate bonds. Arsenic (As) lies directly below P on the periodic table and so the two elements share many chemical properties, although their chemistries are sufficiently dissimilar that As cannot directly replace ...
Tópico(s): Environmental Toxicology and Ecotoxicology
2009 - Cambridge University Press | International Journal of Astrobiology
Felisa Wolfe‐Simon, Valentin Starovoytov, John R. Reinfelder, Oscar Schofield, Paul G. Falkowski,
Superoxide dismutase (SOD) catalyzes the transformation of superoxide to molecular oxygen and hydrogen peroxide. Of the four known SOD isoforms, distinguished by their metal cofactor (iron, manganese [Mn], copper/zinc, nickel), MnSOD is the dominant form in the diatom Thalassiosira pseudonana. We cloned the MnSOD gene, sodA, using the expression vector pBAD, overexpressed the product in Escherichia coli, and purified the mature protein (TpMnSOD). This recombinant enzyme was used to generate a polyclonal ...
Tópico(s): Microbial Fuel Cells and Bioremediation
2006 - Oxford University Press | PLANT PHYSIOLOGY
Felisa Wolfe‐Simon, Daniel Grzebyk, Oscar Schofield, Paul G. Falkowski,
Superoxide dismutases (SOD) catalyze the disproportionation of the potentially destructive superoxide anion radical (O 2 •− , a byproduct of aerobic metabolism) to molecular oxygen and hydrogen peroxide: 2O 2 •− +2H + →H 2 O 2 +O 2 . Based on metal cofactors, four known metalloforms of SOD enzymes have been identified: they contain either Fe, Mn, Cu and Zn, or Ni. Orthologs of all metalloforms are present in oxygenic photoautotrophs. The expression of SOD is highly regulated, with specific metalloforms playing an ...
Tópico(s): Mitochondrial Function and Pathology
2005 - Wiley | Journal of Phycology
Three weeks ago, NASA astrobiology fellow Felisa Wolfe-Simon published a paper in Science about bacteria that can use arsenic instead of phosphorus in DNA and other biomolecules. Then came a ...
Tópico(s): Science, Research, and Medicine
2010 - American Association for the Advancement of Science | Science
Jennifer B. Glass, Amisha T. Poret‐Peterson, Felisa Wolfe‐Simon, Ariel D. Anbar,
We studied the effect of molybdenum (Mo) concentration on transcription and translation of a putative Mo-storage protein (Mop) in the freshwater heterocystous cyanobacterium, Nostoc sp. PCC 7120. Triplicate treatments were acclimated to 1, 150, and 3000 nM Mo over an 11-day period (three transfers) and then transferred into 3000 nM Mo media. Growth rates in 1 nM treatments declined throughout the acclimation period and increased significantly after the final transfer into media containing 3000 nM Mo. ...
Tópico(s): Metalloenzymes and iron-sulfur proteins
2013 - Scientific Research Publishing | Advances in Microbiology
Felisa Wolfe‐Simon, Paul Davies, Ariel D. Anbar,
Abstract All known life requires phosphorus (P) in the form of inorganic phosphate (PO<sub>4</sub><sup>-</sup> or P<sub>i</sub>) and phosphate-containing organic molecules. P<sub>i</sub> serves as the backbone of the nucleic acids that constitute genetic material and as the major repository of chemical energy for metabolism in polyphosphate bonds. Arsenic (As) lies directly below P on the periodic table and so the two elements share many chemical properties, ...
Tópico(s): Evolution and Genetic Dynamics
2008 - Nature Portfolio | Nature Precedings
... the manipulations of his student became known, or Felisa Wolfe-Simon, who called her arsenic-less strain of bacteria “GFAJ1″: give Felisa a job. As I remarked long ago, the ...
Tópico(s): Higher Education Governance and Development
2015 - Wiley | The Winnower
... from the implausibility of the claim made by Felisa Wolfe-Simon et al., numerous weaknesses in the experimental observations ...
Tópico(s): Space Science and Extraterrestrial Life
2011 - American Society for Microbiology | Microbe Magazine
... and for other areas of research on Earth. Felisa Wolfe‐Simon, a NASA Astrobiology Research Fellow in residence at ...
Tópico(s): Space Science and Extraterrestrial Life
2010 - Wiley | Eos
Petra Fromme, Devendra Kumar Chauhan, Mihaela Folea, Craig C. Jolley, Roman Kouřil, Carolyn E. Lubner, Su Lin, Dorota Kolber, Felisa Wolfe‐Simon, John H. Golbeck, Egbert J. Boekema,
Iron availability is a major limiting factor for photosynthesis and hence for life in most of the aquatic environments on earth. Cyanobacteria are important primary producers and prevail over Fe- deficiency by de-repressing the isiAB operon, which codes for the antenna protein IsiA and flavodoxin. We demonstrate that under nanomolar iron concentrations, a giant IsiA-Photosystem I supercomplex is formed, consisting of a Photosystem I trimer encircled by two complete IsiA rings with 18 and 25 copies ...
Tópico(s): Plant Micronutrient Interactions and Effects
2010 - Elsevier BV | Biophysical Journal