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1. Initial Results from the New Horizons Exploration of 2014 MU69, a Small Kuiper Belt Object

Author

S. A. Stern, H. A. Weaver, J. R. Spencer, C. B. Olkin, G. R. Gladstone, W. M. Grundy, J. M. Moore, D. P. Cruikshank, H. A. Elliott, W. B. McKinnon, J. Wm. Parker, A. J. Verbiscer, L. A. Young, D. A. Aguilar, J. M. Albers, T. Andert, J. P. Andrews, F. Bagenal, M. E. Banks, B. A. Bauer, J. A. Bauman, K. E. Bechtold, C. B. Beddingfield, N. Behrooz, K. B. Beisser, S. D. Benecchi, E. Bernardoni, R. A. Beyer, S. Bhaskaran, C. J. Bierson, R. P. Binzel, E. M. Birath, M. K. Bird, D. R. Boone, A. F. Bowman, V. J. Bray, D. T. Britt, L. E. Brown, M. R. Buckley, M. W. Buie, B. J. Buratti, L. M. Burke, S. S. Bushman, B. Carcich, A. L. Chaikin, C. L. Chavez, A. F. Cheng, E. J. Colwell, S. J. Conard, M. P. Conner, C. A. Conrad, J. C. Cook, S. B. Cooper, O. S. Custodio, C. M. Dalle Ore, C. C. DeBoy, P. Dharmavaram, R. D. Dhingra, G. F. Dunn, A. M. Earle, A. F. Egan, J. Eisig, M. R. El-Maarry, C. Engelbrecht, B. L. Enke, C. J. Ercol, E. D. Fattig, C. L. Ferrell, T. J. Finley, J. Firer, J. Fischetti, W. M. Folkner, M. N. Fosbury, G. H. Fountain, J. M. Freeze, L. Gabasova, L. S. Glaze, J. L. Green, G. A. Griffith, Y. Guo, M. Hahn, D. W. Hals, D. P. Hamilton, S. A. Hamilton, J. J. Hanley, A. Harch, K. A. Harmon, H. M. Hart, J. Hayes, C. B. Hersman, M. E. Hill, T. A. Hill, J. D. Hofgartner, M. E. Holdridge, M. Horanyi, A. Hosadurga, A. D. Howard, C. J. A. Howett, S. E. Jaskulek, D. E. Jennings, J. R. Jensen, M. R. Jones, H. K. Kang, D. J. Katz, D. E. Kaufmann, J. J. Kavelaars, J. T. Keane, G. P. Keleher, M. Kinczyk, M. C. Kochte, P. Kollmann, S. M. Krimigis, G. L. Kruizinga, D. Y. Kusnierkiewicz, M. S. Lahr, T. R. Lauer, G. B. Lawrence, J. E Lee, E. J. Lessac-Chenen, I. R. Linscott, C. M. Lisse, A. W. Lunsford, D. M. Mages, V. A. Mallder, N. P. Martin, B. H. May, D. J. McComas, R. L. McNutt, Jr, D. S. Mehoke, T. S. Mehoke, D. S. Nelson, H. D. Nguyen, J. I. Nunez, A. C. Ocampo, W. M. Owen, G. K. Oxton, A. H. Parker, M. Paetzold, J. Y. Pelgrift, F. J. Pelletier, J. P. Pineau, M. R. Piquette, S. B. Porter, S. Protopapa, E. Quirico, J. A. Redfern, A. L. Regiec, H. J. Reitsema, D. C. Reuter, D. C. Richardson, J. E. Riedel, M. A. Ritterbush, S. J. Robbins, D. J. Rodgers, G. D. Rogers, D. M. Rose, P. E. Rosendall, K. D. Runyon, M. G. Ryschkewitsch, M. M. Saina, M. J. Salinas, P. M. Schenk, J. R. Scherrer, W. R. Schlei, B. Schmitt, D. J. Schultz, D. C. Schurr, F. Scipioni, R. L. Sepan, R. G. Shelton, M. R. Showalter, M. Simon, K. N. Singer, E. W. Stahlheber, D. R. Stanbridge, J. A. Stansberry, A. J. Steffl, D. F. Strobel, M. M. Stothoff, T. Stryk, J. R. Stuart, M. E. Summers, M. B. Tapley, A. Taylor, H. W. Taylor, R. M. Tedford, H. B. Throop, L. S. Turner, O. M. Umurhan, J. Van Eck, D. Velez, M. H. Versteeg, M. A. Vincent, R. W. Webbert, S. E. Weidner, G. E. Weigle, II, J. R. Wendel, O. L. White, K. E. Whittenburg, B. G. Williams, K. E. Williams, S. P. Williams, H. L. Winters, A. M. Zangari, and T. H. Zurbuchen

Subjects
Astrophysics
Abstract

The Kuiper Belt is a broad, torus-shaped region in the outer Solar System beyond Neptune’s orbit. It contains primordial planetary building blocks and dwarf planets. NASA’s New Horizons spacecraft conducted a flyby of Pluto and its system of moons on 14 July 2015. New Horizons then continued farther into the Kuiper Belt, adjusting its trajectory to fly close to the small Kuiper Belt object (486958) 2014 MU69 (henceforth MU69; also informally known as Ultima Thule). Stellar occultation observations in 2017 showed that MU69 was ~25 to 35 km in diameter, and therefore smaller than the diameter of Pluto (2375 km) by a factor of ~100 and less massive than Pluto by a factor of ~106. MU69 is located about 1.6 billion kilometers farther from the Sun than Pluto was at the time of the New Horizons flyby. MU69’s orbit indicates that it is a “cold classical” Kuiper Belt object, thought to be the least dynamically evolved population in the Solar System. A major goal of flying past this target is to investigate accretion processes in the outer Solar System and how those processes led to the formation of the planets. Because no small Kuiper Belt object had previously been explored by spacecraft, we also sought to provide a close-up look at such a body’s geology and composition, and to search for satellites, rings, and evidence of present or past atmosphere. We report initial scientific results and interpretations from that flyby.

Published
2019
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2. Initial results from the New Horizons exploration of 2014 MU 69 , a small Kuiper Belt object

Author

J. Fischetti, S. Bhaskaran, Matthias Hahn, Karl Whittenburg, Derek S. Nelson, G. A. Griffith, Amanda M. Zangari, B. J. Buratti, James T. Keane, E. J. Lessac-Chenen, Ralph L. McNutt, Tiffany J. Finley, J. Scherrer, M. A. Ritterbush, M. M. Saina, G. Dunn, T. A. Hill, J. Van Eck, T. Stryk, J. M. Albers, D. C. Reuter, C. M. Dalle Ore, H. A. Elliott, D. J. Schultz, J. Andrews, Douglas P. Hamilton, M. H. Versteeg, Orkan M. Umurhan, Matthew E. Hill, Hai Nguyen, M. Simon, L. Gabasova, D. E. Jennings, D. J. Katz, J. E. Riedel, N. Behrooz, M. N. Fosbury, Henry B. Throop, A. J. Verbiscer, E. Bernardoni, Ross A. Beyer, C. Engelbrecht, Francesca Scipioni, H. L. Winters, Thomas H. Zurbuchen, Carey M. Lisse, Veronica J. Bray, M. G. Ryschkewitsch, Stuart J. Robbins, S. E. Jaskulek, M. C. Kochte, Thomas Mehoke, M. S. Lahr, M. J. Salinas, V. A. Mallder, S. P. Williams, B. H. May, D. M. Mages, C. C. Deboy, Simon B. Porter, Gerhard Kruizinga, Marc W. Buie, Jorge I. Nunez, John Hayes, Peter Kollmann, P. Dharmavaram, J. M. Moore, Darrell F. Strobel, John Stansberry, R. P. Binzel, H. M. Hart, Jillian Redfern, E. W. Stahlheber, H. K. Kang, James L. Green, Anthony F. Egan, Carly Howett, Fran Bagenal, Dale Stanbridge, Chris B. Hersman, C. L. Chavez, Debi Rose, J. Y. Pelgrift, Maria E. Banks, D. C. Schurr, Matthew R. Buckley, L. S. Turner, Ivan Linscott, Kaj E. Williams, J. Eisig, Mihaly Horanyi, Matthew Jones, Mark R. Showalter, William B. McKinnon, Leslie A. Young, E. J. Colwell, Daniel T. Britt, Kirby Runyon, David J. McComas, G. Weigle, Bernard Schmitt, Susan D. Benecchi, Alissa M. Earle, M. J. Kinczyk, Tod R. Lauer, M. R. Piquette, Lori S. Glaze, Carver J. Bierson, L. M. Burke, Brian Carcich, O. S. Custodio, A. Harch, Harold A. Weaver, Dale P. Cruikshank, Oliver L. White, L. E. Brown, William M. Grundy, G. K. Oxton, Chelsea L. Ferrell, David E. Kaufmann, Mohamed Ramy El-Maarry, K. A. Harmon, W. R. Schlei, Eric Quirico, Derek C. Richardson, J. M. Freeze, Jennifer Hanley, R. G. Shelton, Andrew J. Steffl, Mike Bird, H. W. Taylor, Harold J. Reitsema, Stamatios M. Krimigis, D. R. Boone, E. D. Fattig, A. L. Regiec, D. J. Rodgers, Jason D. Hofgartner, D. Velez, Catherine B. Olkin, Kelsi N. Singer, Brian Bauer, Carl J. Ercol, Martin Pätzold, Nicole Martin, Stewart Bushman, J. Firer, Allen W. Lunsford, R. W. Webbert, A. L. Chaikin, Alex Parker, C. A. Conrad, M. P. Conner, S. B. Cooper, Chloe B. Beddingfield, William M. Folkner, J. E. Lee, M. B. Tapley, G. R. Gladstone, D. A. Aguilar, Glen H. Fountain, Emma Birath, Rebecca Sepan, Jeremy Bauman, J. Wm. Parker, S. Weidner, J. R. Jensen, Jason C. Cook, Alan D. Howard, William M. Owen, Andrew F. Cheng, B. L. Enke, Sarah A. Hamilton, Tom Andert, K. B. Beisser, K. E. Bechtold, J. R. Wendel, Rajani D. Dhingra, Paul M. Schenk, Michael E. Summers, J. R. Spencer, D. W. Hals, Silvia Protopapa, A. C. Ocampo, Mark E. Holdridge, S. A. Stern, A. Taylor, R. M. Tedford, G. P. Keleher, Gabe Rogers, Frederic Pelletier, Jj Kavelaars, Yanping Guo, Jon Pineau, Steven J. Conard, Alice Bowman, A. Hosadurga, B. G. Williams, Michael Vincent, David Y. Kusnierkiewicz, Paul E. Rosendall, G. B. Lawrence, J. R. Stuart, M. M. Stothoff, Jr. D. S. Mehoke, Southwest Research Institute [Boulder] (SwRI), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Lowell Observatory [Flagstaff], Space Physics Research Laboratory [Ann Arbor] (SPRL), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, SwRI Planetary Science Directorate [Boulder], Universitat de Lleida, Institut für Raumfahrttechnik, Universität der Bundeswehr München [Neubiberg], Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Department of Space Studies [Boulder], Rheinische Friedrich-Wilhelms-Universität Bonn, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institute of Hydrology, NASA Goddard Space Flight Center (GSFC), Department of Physics, Chemistry and Biology [Linköping] (IFM), Linköping University (LIU), Africa Rice Center [Bénin] (AfricaRice), Africa Rice Center [Côte d'Ivoire] (AfricaRice), Consultative Group on International Agricultural Research [CGIAR] (CGIAR)-Consultative Group on International Agricultural Research [CGIAR] (CGIAR), Yonsei University, Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre International de Hautes Etudes Agronomiques Méditerranéennes - Institut Agronomique Méditerranéen de Montpellier (CIHEAM-IAMM), Centre International de Hautes Études Agronomiques Méditerranéennes (CIHEAM), Princeton University, Reed College, Hanoi National University of Education (HNUE), Rhenish Institute for Environmental Research (RIU), University of Cologne, School of Earth, Atmospheric and Environmental Sciences [Manchester] (SEAES), University of Manchester [Manchester], ESA, Southwest Research Institute [San Antonio] (SwRI), NASA Ames Research Center (ARC), Laboratoire pour l'utilisation du rayonnement électromagnétique (LURE), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-MENRT-Centre National de la Recherche Scientifique (CNRS), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Johns Hopkins University (JHU), Institute of Physics of the Czech Academy of Sciences (FZU / CAS), Czech Academy of Sciences [Prague] (CAS), Laboratoire de Chimie Analytique Bio-Inorganique et Environnement (LCABIE), Université de Pau et des Pays de l'Adour (UPPA)-Centre National de la Recherche Scientifique (CNRS), Department of Biochemistry, Faculty of Biology, University of Warmia and Mazury [Olsztyn], California Institute of Technology (CALTECH)-NASA, Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), University of Warmia and Mazury, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), inconnu temporaire UPEMLV, Inconnu, INGENIERIE (INGENIERIE), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Génie des Procédés Plasmas et Traitement de Surface (ENSCP), PARIS, Africa Rice Center, Africa Rice Center (AfricaRice), Institut de pharmacologie moléculaire et cellulaire (IPMC), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015 - 2019) (COMUE UCA)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Institute of Physics of Academy of Sciences of Czech Republic, and Czech Academy of Sciences [Prague] (ASCR)

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Solar System, Multidisciplinary, 010504 meteorology & atmospheric sciences, Spacecraft, business.industry, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Astronomy, Coma (optics), Contact binary, Albedo, 01 natural sciences, Object (philosophy), Solar wind, 13. Climate action, 0103 physical sciences, Pebble, business, 010303 astronomy & astrophysics, Geology, ComputingMilieux_MISCELLANEOUS, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences
Abstract

The Kuiper Belt is a distant region of the Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU69, a Cold Classical Kuiper Belt Object, a class of objects that have never been heated by the Sun and are therefore well preserved since their formation. Here we describe initial results from these encounter observations. MU69 is a bi-lobed contact binary with a flattened shape, discrete geological units, and noticeable albedo heterogeneity. However, there is little surface color and compositional heterogeneity. No evidence for satellites, ring or dust structures, gas coma, or solar wind interactions was detected. By origin MU69 appears consistent with pebble cloud collapse followed by a low velocity merger of its two lobes., 43 pages, 8 figure

Published
2019

3. Initial results from the New Horizons exploration of 2014 MU

Author

S A, Stern, H A, Weaver, J R, Spencer, C B, Olkin, G R, Gladstone, W M, Grundy, J M, Moore, D P, Cruikshank, H A, Elliott, W B, McKinnon, J Wm, Parker, A J, Verbiscer, L A, Young, D A, Aguilar, J M, Albers, T, Andert, J P, Andrews, F, Bagenal, M E, Banks, B A, Bauer, J A, Bauman, K E, Bechtold, C B, Beddingfield, N, Behrooz, K B, Beisser, S D, Benecchi, E, Bernardoni, R A, Beyer, S, Bhaskaran, C J, Bierson, R P, Binzel, E M, Birath, M K, Bird, D R, Boone, A F, Bowman, V J, Bray, D T, Britt, L E, Brown, M R, Buckley, M W, Buie, B J, Buratti, L M, Burke, S S, Bushman, B, Carcich, A L, Chaikin, C L, Chavez, A F, Cheng, E J, Colwell, S J, Conard, M P, Conner, C A, Conrad, J C, Cook, S B, Cooper, O S, Custodio, C M, Dalle Ore, C C, Deboy, P, Dharmavaram, R D, Dhingra, G F, Dunn, A M, Earle, A F, Egan, J, Eisig, M R, El-Maarry, C, Engelbrecht, B L, Enke, C J, Ercol, E D, Fattig, C L, Ferrell, T J, Finley, J, Firer, J, Fischetti, W M, Folkner, M N, Fosbury, G H, Fountain, J M, Freeze, L, Gabasova, L S, Glaze, J L, Green, G A, Griffith, Y, Guo, M, Hahn, D W, Hals, D P, Hamilton, S A, Hamilton, J J, Hanley, A, Harch, K A, Harmon, H M, Hart, J, Hayes, C B, Hersman, M E, Hill, T A, Hill, J D, Hofgartner, M E, Holdridge, M, Horányi, A, Hosadurga, A D, Howard, C J A, Howett, S E, Jaskulek, D E, Jennings, J R, Jensen, M R, Jones, H K, Kang, D J, Katz, D E, Kaufmann, J J, Kavelaars, J T, Keane, G P, Keleher, M, Kinczyk, M C, Kochte, P, Kollmann, S M, Krimigis, G L, Kruizinga, D Y, Kusnierkiewicz, M S, Lahr, T R, Lauer, G B, Lawrence, J E, Lee, E J, Lessac-Chenen, I R, Linscott, C M, Lisse, A W, Lunsford, D M, Mages, V A, Mallder, N P, Martin, B H, May, D J, McComas, R L, McNutt, D S, Mehoke, T S, Mehoke, D S, Nelson, H D, Nguyen, J I, Núñez, A C, Ocampo, W M, Owen, G K, Oxton, A H, Parker, M, Pätzold, J Y, Pelgrift, F J, Pelletier, J P, Pineau, M R, Piquette, S B, Porter, S, Protopapa, E, Quirico, J A, Redfern, A L, Regiec, H J, Reitsema, D C, Reuter, D C, Richardson, J E, Riedel, M A, Ritterbush, S J, Robbins, D J, Rodgers, G D, Rogers, D M, Rose, P E, Rosendall, K D, Runyon, M G, Ryschkewitsch, M M, Saina, M J, Salinas, P M, Schenk, J R, Scherrer, W R, Schlei, B, Schmitt, D J, Schultz, D C, Schurr, F, Scipioni, R L, Sepan, R G, Shelton, M R, Showalter, M, Simon, K N, Singer, E W, Stahlheber, D R, Stanbridge, J A, Stansberry, A J, Steffl, D F, Strobel, M M, Stothoff, T, Stryk, J R, Stuart, M E, Summers, M B, Tapley, A, Taylor, H W, Taylor, R M, Tedford, H B, Throop, L S, Turner, O M, Umurhan, J, Van Eck, D, Velez, M H, Versteeg, M A, Vincent, R W, Webbert, S E, Weidner, G E, Weigle, J R, Wendel, O L, White, K E, Whittenburg, B G, Williams, K E, Williams, S P, Williams, H L, Winters, A M, Zangari, and T H, Zurbuchen

Abstract

The Kuiper Belt is a distant region of the outer Solar System. On 1 January 2019, the New Horizons spacecraft flew close to (486958) 2014 MU

Published
2019

4. Influence of pH on Ammonia Accumulation and Toxicity in Halophilic, Methylotrophic Methanogens

Author

P C Kadam and D R Boone

Subjects
Ecology, Alanine dehydrogenase, Intracellular pH, Glutamate dehydrogenase, Biology, Methanohalophilus, biology.organism_classification, Applied Microbiology and Biotechnology, chemistry.chemical_compound, Ammonia, chemistry, Biochemistry, Glutamine synthetase, Methanomicrobiales, Ammonium, Research Article, Food Science, Biotechnology, Nuclear chemistry
Abstract

We studied the effects of pH and ammonia concentration on the growth of three methanogens. These three halophilic, methylotrophic methanogens, Methanolobus bombayensis, Methanolobus taylorii, and Methanohalophilus zhilinaeae, grew at environmental pH ranges that overlapped with each other and spanned the pH range from 7.0 to 9.5. During growth they had reversed membrane pH gradients ((Delta)pH) at all pH values tested. The (Delta)pH was in the range of -0.4 to -0.9 pH units, with the cytosol being more acidic than the environmental pH. Methanohalophilus zhilinaeae had the most negative (Delta)pH (-0.9 pH units). These negative pH gradients resulted in the accumulation of ammonium (NH(inf4)(sup+)), and when grown at the highest external ammonia concentrations that allowed good growth, cells had cytosolic NH(inf4)(sup+) concentrations as high as 180 mM. The high concentrations of cytosolic NH(inf4)(sup+) were accompanied by greater (Delta)pH and lower concentrations of the major cytosolic cation K(sup+) (compared with cells grown in medium with only 5 mM ammonia). Methanolobus bombayensis and Methanolobus taylorii were more sensitive to total external ammonia at higher external pH values, but the inhibitory concentration of un-ionized ammonia that resulted in a 50% reduction of the growth rate was about 2 to 5 mM, regardless of the pH. This is consistent with growth inhibition by ammonia in other bacteria. However, Methanohalophilus zhilinaeae was more resistant to un-ionized ammonia than any other known organism. It had a 50% inhibitory concentration for un-ionized ammonia of 13 mM at pH 8.5 and 45 mM at pH 9.5. We examined the effects of pH on three ammonia-assimilating activities (glutamine synthetase, glutamate dehydrogenase, and alanine dehydrogenase) in cell lysates and found that the pH ranges were consistent with the observed ranges of intracellular pH.

Published
1996

5. Clues from a halophilic methanogen about aromatic amino acid biosynthesis in archaebacteria

Author

D. R. Boone, Carol A. Bonner, R. S. Fischer, and Roy A. Jensen

Subjects
biology, Prephenate dehydrogenase, Prephenate dehydratase, General Medicine, biology.organism_classification, Biochemistry, Microbiology, Cofactor, chemistry.chemical_compound, chemistry, Genetics, Aromatic amino acids, biology.protein, Chorismate mutase, Methanomicrobiales, NAD+ kinase, Methanohalophilus mahii, Molecular Biology
Abstract

Extensive diversity in features of aromatic amino acid biosynthesis and regulation has become recognized in eubacteria, but almost nothing is known about the extent to which such diversity exists within the archaebacteria. Methanohalophilus mahii, a methylotrophic halophilic methanogen, was found to synthesize l-phenylalanine and l-tyrosine via phenylpyruvate and 4-hydroxyphenylpyruvate, respectively. Enzymes capable of using l-arogenate as substrate were not found. Prephenate dehydrogenase was highly sensitive to feedback inhibition by l-tyrosine and could utilize either NADP+ (preferred) or NAD+ as cosubstrate. Tyrosine-pathway dehydrogenases having the combination of narrow specificity for a cyclohexadienyl substrate but broad specificity for pyridine nucleotide cofactor have not been described before. The chorismate mutase enzyme found is a member of a class which is insensitive to allosteric control. The most noteworthy character state was prephenate dehydratase which proved to be subject to multimetabolite control by feedback inhibitor (l-phenylalanine) and allosteric activators (l-tyrosine, l-tryptophan, l-leucine, l-methionine and l-isoleucine). This interlock type of prephenate dehydratase, also known to be broadly distributed among the gram-positive lineage of the eubacteria, was previously shown to exist in the extreme halophile, Halobacterium vallismortis. The results are consistent with the conclusion based upon 16S rRNA analyses that Methanomicrobiales and the extreme halophiles cluster together.

Published
1993

6. Osmotic adaptation of moderately halophilic methanogenic Archaeobacteria, and detection of cytosolicN,N-dimethylglycine

Author

J. C. Duarte, J. A. G. F. Menaia, and D. R. Boone

Subjects
Pharmacology, Chromatography, Lysis, Osmotic concentration, Cell Biology, Biology, Methanohalophilus, biology.organism_classification, Cellular and Molecular Neuroscience, chemistry.chemical_compound, Chemically defined medium, Betaine, chemistry, Biochemistry, Osmolyte, Molecular Medicine, Osmoprotectant, Methanohalophilus mahii, Molecular Biology
Abstract

Methanohalophilus mahii SLP andMethanohalophilus halophilus Z-7982, two closely-related, moderately halophilic, methylotrophic methanogens, were tested for their adaptation to saline conditions. They grew in a wider range of salinities than previously reported, in a defined medium with as little as 0.1 M NaCl, and with a high as 4.0 M NaCl forM. halophilus and 4.5 M NaCl forM. mahii. Fastest growth occurred with 1.5 M NaCl forM. mahii and 1.0 M NaCl forM. halophilus. M. mahii also grew in media in which NaCl was replaced by sucrose or KCl as osmolytes up to the osmolal equivalent of 2 and 2.5 M NaCl (these media contained other sodium salts totaling about 0.1 M Na+). In media with either sucrose of KCl replacing NaCl,M. mahii grew fastest at osmolalities approximately equiosmolal to 1 M NaCl.M. mahii not only grew well at a wide range of osmosities, it also tolerated rapid shifts in osmolality. Cells subjected to a rapid 10-fold hypertonic shift resumed growth without a prolonged lag. When cells were subjected to a rapid 10-fold hypotonic shift, 90% of cells lysed, but the remaineder continued to swell with little further lysis during the next 45 min. Surviving cells resumed growth.Methanohalophilus strains grown in defined medium had low cytosolic Na+ concentrations; K+ concentrations were as high as 0.35 M. Organic osmotica in the cytosol include glycine betaine and larger amounts of N,N-dimethylglycine.

Published
1993

8. Occurrence of beta-glutamate, a novel osmolyte, in marine methanogenic bacteria

Author

Mary F. Roberts, N Belay, D. R. Boone, Diane E. Robertson, and K O Stetter

Subjects
inorganic chemicals, Methanococcus, Magnetic Resonance Spectroscopy, Ecology, biology, Methanogenium, Thermophile, Euryarchaeota, biology.organism_classification, Applied Microbiology and Biotechnology, Methanogen, Methanococci, Glutamates, Methanococcales, Biochemistry, Potassium, Seawater, Methanomicrobiales, Water Microbiology, Research Article, Food Science, Biotechnology
Abstract

The unusual compound beta-aminoglutaric acid (beta-glutamate) has been identified by 13C nuclear magnetic resonance spectroscopy in soluble extracts of marine methanogenic bacteria. We examined several methanogen species representing nine genera and found that beta-glutamate occurred in methanococci and two methanogenium strains (Methanogenium cariaci JR1 and "Methanogenium anulus" AN9). The presence of this compound in the methanococci examined was further restricted to thermophilic members of the genus Methanococcus, including Methanococcus thermolithotrophicus strains, Methanococcus jannaschii, and "Methanococcus igneus." The two Methanogenium strains examined were mesophiles. Studies using Methanococcus thermolithotrophicus showed that levels of beta-glutamate in cells of that species were not affected by variation in growth temperature (40 to 65 degrees C), NH4+ (2 to 80 mM), Mg2+ (10 to 50 mM), or K+ (2 to 10 mM) in the medium. In contrast, soluble pools of beta-glutamate and L-alpha-glutamate (the other major free amino acid in all the methanococci) were proportional to NaCl levels in the growth medium. This dependence of beta-glutamate and L-alpha-glutamate concentrations on salt levels in the medium suggests that they function as osmolytes in these cells.

Published
1990

9. Detection of the osmoregulator betaine in methanogens

Author

Mary F. Roberts, D. R. Boone, J. A. G. F. Menaia, Diane E. Robertson, and D. Noll

Subjects
Magnetic Resonance Spectroscopy, Ecology, Methanogenium, biology, Chemistry, Stereochemistry, Euryarchaeota, Water-Electrolyte Balance, Membrane transport, biology.organism_classification, Applied Microbiology and Biotechnology, Culture Media, Betaine, chemistry.chemical_compound, Biochemistry, Glycine, Osmoregulation, Yeast extract, Methanohalophilus mahii, Research Article, Food Science, Biotechnology
Abstract

Trimethyl glycine (glycine betaine) was detected by 13C nuclear magnetic resonance spectroscopy at high intracellular concentrations in several methanogens (Methanogenium cariaci, "Methanogenium anulus" AN9, Methanohalophilus zhilinae, Methanohalophilus mahii, and Methanococcus voltae) grown on marine media containing yeast extract. 13C labeling studies with Methanogenium cariaci suggested that the betaine which accumulated inside the cells was not synthesized de novo but was transported in from the medium. Proof of such a transport system was provided by growing Methanogenium cariaci on yeast-free medium supplemented with betaine. Under these conditions, betaine was the dominant osmoregulator.

Published
1990

10. Potassium extrusion by the moderately halophilic and alkaliphilic methanogen methanolobus taylorii GS-16 and homeostasis of cytosolic pH

Author

D R Boone, S Ni, and J E Boone

Subjects
Antiporter, Potassium, Sodium, chemistry.chemical_element, Biology, Alkalies, Microbiology, Valinomycin, chemistry.chemical_compound, Cytosol, Homeostasis, Molecular Biology, Membrane potential, Dose-Response Relationship, Drug, Chemiosmosis, Biological Transport, Hydrogen-Ion Concentration, Archaea, Anti-Bacterial Agents, chemistry, Biochemistry, Salts, Protons, Methane, Cell Division, Nuclear chemistry, Research Article
Abstract

Methanolobus taylorii GS-16, a moderately halophilic and alkaliphilic methanogen, grows over a wide pH range, from 6.8 to 9.0. Cells suspended in medium with a pH above 8.2 reversed their transmembrane pH gradient (delta pH), making their cytosol more acidic than the medium. The decreased energy in the proton motive force due to the reversed delta pH was partly compensated by an increased electric membrane potential (delta psi). The cytosolic acidification by M. taylorii at alkaline pH values was accompanied by K+ extrusion. The cytosolic K+ concentration was 110 mM in cells suspended at pH 8.7, but it was 320 mM in cells suspended at neutral pH values. High external K+ concentrations (210 mM or higher) inhibited the growth of M. taylorii at alkaline pH values, perhaps by preventing K+ extrusion. Cells suspended at pH 8.5 and 300 mM external K+ failed to acidify their cytosol. The key observation indicative of the involvement of K+ transport in cytosolic acidification was that valinomycin (0.8 microM), a K+ uniporter, inhibited the growth of M. taylorii only at alkaline pH values. Experiments with resting cells indicated that at alkaline pH values valinomycin uncoupled catabolic reactions from ATP synthesis. Thus, K+/H+ antiport activity was proposed to account for the K+ extrusion and the uncoupling effect of valinomycin at alkaline pH values. Such antiport activity was demonstrated by the sharp drop in pH of the bulk medium of the cell suspension upon the addition of 0.1 M KCl. The antiporter appeared to be active only at alkaline pH values, which was in accordance with a possible role in pH homeostasis by M. taylorii growing at alkaline pH values.

Published
1994

11. Methanogenesis from Propionate in Sludge and Enrichment Systems

Author

Ann C. Wilkie, Paul H. Smith, L.-Y. Xun, D. R. Boone, Robert A. Mah, and B. Ahring

Subjects
chemistry.chemical_classification, animal structures, biology, Methanogenesis, Heterotroph, biology.organism_classification, Methane, chemistry.chemical_compound, chemistry, Environmental chemistry, Propionate, Organic matter, Fermentation, Formate, Bacteria
Abstract

The biological formation of methane from organic matter is a complex microbiological process involving many physiologically dependent relationships between and among a diversity of heterotrophic fermentative and methanogenic bacteria. The methanogenic metabolism of all organic matter leads to the formation of the same types of intermediates namely H2, C02, and formate, acetic, propionic, and butyric acids. These compounds are, in turn, converted directly or indirectly to methane by methanogenic bacteria alone or acting together with non-methanogenic heterotrophs. These latter organisms may be syntrophic partners of the methanogens or simply members of a broader food-chain. Estimates on the sum:total of the fermentative contributions by these few metabolic intermediates account for 100% of the methane formed in a typical digestor. The importance of acetate as a direct methanogenic intermediate is already well established (5,6). Evidence points to a more complicated role played by the metabolism of butyrate and propionate in this fermentation. The main focus of the present paper is to examine the role of propionate in methanogenesis not only to re-assess its importance as a source of methane or methanogenic precursors in digestors but also to examine the biochemical and physiological basis for its conversion to methane.

Published
1990

16. Language impairment in dementia

Author

K A, Bayles, D R, Boone, A W, Kaszniak, and L Z, Stern

Subjects
Language Disorders, Humans, Dementia, Cognition Disorders
Published
1982

17. Our profession--where is it?

Author

D R, Boone

Subjects
Hearing, Health Occupations, Humans, Speech Therapy, United States
Published
1976

18. Diffusion of the Interspecies Electron Carriers H(2) and Formate in Methanogenic Ecosystems and Its Implications in the Measurement of K(m) for H(2) or Formate Uptake

Author

D R, Boone, R L, Johnson, and Y, Liu

Subjects
education, General Microbial Ecology
Abstract

We calculated the potential H(2) and formate diffusion between microbes and found that at H(2) concentrations commonly found in nature, H(2) could not diffuse rapidly enough to dispersed methanogenic cells to account for the rate of methane synthesis but formate could. Our calculations were based on individual organisms dispersed in the medium, as supported by microscopic observations of butyrate-degrading cocultures. We isolated an axenic culture of Syntrophomonas wolfei and cultivated it on butyrate in syntrophic coculture with Methanobacterium formicicum; during growth the H(2) concentration was 63 nM (10.6 Pa). S. wolfei contained formate dehydrogenase activity (as does M. formicicum), which would allow interspecies formate transfer in that coculture. Thus, interspecies formate transfer may be the predominant mechanism of syntrophy. Our diffusion calculations also indicated that H(2) concentration at the cell surface of H(2)-consuming organisms was low but increased to approximately the bulk-fluid concentration at a distance of about 10 mum from the surface. Thus, routine estimation of kinetic parameters would greatly overestimate the K(m) for H(2) or formate.

Published
1989

19. ASHA: Why?

Author

D R, Boone

Subjects
Hearing, Health Occupations, Humans, Speech Therapy, Societies, United States
Published
1976

20. Communicative aspects of aging

Author

D R, Boone, K A, Bayles, and C F, Koopmann

Subjects
Aging, Apraxias, Memory, Communication, Dysarthria, Intelligence, Aphasia, Voice, Humans, Speech, Middle Aged, Hearing Disorders, Aged
Published
1982

21. LATERALITY, DOMINANCE, AND LANGUAGE

Author

D R, BOONE

Subjects
Brain, Humans, Nervous System Physiological Phenomena, Psychology, Child, Child, Functional Laterality, Language
Published
1965

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