1
|
El-Maarry MR, Groussin O, Thomas N, Pajola M, Auger AT, Davidsson B, Hu X, Hviid SF, Knollenberg J, Güttler C, Tubiana C, Fornasier S, Feller C, Hasselmann P, Vincent JB, Sierks H, Barbieri C, Lamy P, Rodrigo R, Koschny D, Keller HU, Rickman H, A’Hearn MF, Barucci MA, Bertaux JL, Bertini I, Besse S, Bodewits D, Cremonese G, Da Deppo V, Debei S, De Cecco M, Deller J, Deshapriya JDP, Fulle M, Gutierrez PJ, Hofmann M, Ip WH, Jorda L, Kovacs G, Kramm JR, Kührt E, Küppers M, Lara LM, Lazzarin M, Lin ZY, Lopez Moreno JJ, Marchi S, Marzari F, Mottola S, Naletto G, Oklay N, Pommerol A, Preusker F, Scholten F, Shi X. Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past. Science 2017; 355:1392-1395. [DOI: 10.1126/science.aak9384] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 03/06/2017] [Indexed: 11/02/2022]
Affiliation(s)
- M. Ramy El-Maarry
- Physikalisches Institut, Universität Bern, 3012 Bern, Switzerland
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80301, USA
| | - O. Groussin
- Aix Marseille Université, CNRS, Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - N. Thomas
- Physikalisches Institut, Universität Bern, 3012 Bern, Switzerland
| | - M. Pajola
- NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - A.-T. Auger
- Aix Marseille Université, CNRS, Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - B. Davidsson
- Jet Propulsion Laboratory, Pasadena, CA 91109, USA
| | - X. Hu
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - S. F. Hviid
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - J. Knollenberg
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - C. Güttler
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - C. Tubiana
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - S. Fornasier
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - C. Feller
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - P. Hasselmann
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - J.-B. Vincent
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - H. Sierks
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - C. Barbieri
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - P. Lamy
- Laboratoire d’Astrophysique de Marseille, UMR 7326 CNRS & Université Aix-Marseille, 13388 Marseille Cedex 13, France
| | - R. Rodrigo
- Centro de Astrobiología, Instituto Nacional de Técnica Aeroespacial, 28850 Torrejón de Ardoz, Madrid, Spain
- International Space Science Institute, 3012 Bern, Switzerland
| | - D. Koschny
- Operations Department, European Space Astronomy Centre/ESA, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
| | - H. U. Keller
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
- Institut für Geophysik und Extraterrestrische Physik, Technische Universität Braunschweig, 38106 Braunschweig, Germany
| | - H. Rickman
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
- Polish Academy of Sciences, Space Research Center, 00716 Warsaw, Poland
| | - M. F. A’Hearn
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - M. A. Barucci
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - J.-L. Bertaux
- Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), CNRS–Université de Versailles Saint-Quentin-en-Yvelines–Institut Pierre Simon Laplace, 78280 Guyancourt, France
| | - I. Bertini
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - S. Besse
- Operations Department, European Space Astronomy Centre/ESA, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
| | - D. Bodewits
- Department of Astronomy, University of Maryland, College Park, MD 20742, USA
| | - G. Cremonese
- Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, 35122 Padova, Italy
| | - V. Da Deppo
- Consiglio Nazionale delle Ricerche–Istituto di Fotonica e Nanotecnologie, Unità Organizzativa di Supporto, Padova Luxor, 35131 Padova, Italy
| | - S. Debei
- Department of Industrial Engineering, University of Padova, 35131 Padova, Italy
| | | | - J. Deller
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - J. D. P. Deshapriya
- LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Paris Diderot, Sorbonne Paris Cité, UPMC Université Paris 06, Sorbonne Universités, Meudon Principal Cedex 92195, France
| | - M. Fulle
- INAF, Osservatorio Astronomico di Trieste, 34014 Trieste, Italy
| | - P. J. Gutierrez
- Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - M. Hofmann
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - W.-H. Ip
- Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan
| | - L. Jorda
- Aix Marseille Université, CNRS, Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388 Marseille, France
| | - G. Kovacs
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - J.-R. Kramm
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| | - E. Kührt
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - M. Küppers
- Operations Department, European Space Astronomy Centre/ESA, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
| | - L. M. Lara
- Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - M. Lazzarin
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - Z.-Yi Lin
- Graduate Institute of Astronomy, National Central University, Chung-Li 32054, Taiwan
| | - J. J. Lopez Moreno
- Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomía s/n, 18008 Granada, Spain
| | - S. Marchi
- Solar System Exploration Research, Virtual Institute, Southwest Research Institute, Boulder, CO 80302, USA
| | - F. Marzari
- Department of Physics and Astronomy, University of Padova, 35122 Padova, Italy
| | - S. Mottola
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - G. Naletto
- Consiglio Nazionale delle Ricerche–Istituto di Fotonica e Nanotecnologie, Unità Organizzativa di Supporto, Padova Luxor, 35131 Padova, Italy
- Department of Information Engineering, University of Padova, 35131 Padova, Italy
- Centro di Ateneo di Studi ed Attivitá Spaziali “Giuseppe Colombo” (CISAS), University of Padova, 35131 Padova, Italy
| | - N. Oklay
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - A. Pommerol
- Physikalisches Institut, Universität Bern, 3012 Bern, Switzerland
| | - F. Preusker
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - F. Scholten
- Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, 12489 Berlin, Germany
| | - X. Shi
- Max-Planck-Institut für Sonnensystemforschung, 37077 Göttingen, Germany
| |
Collapse
|
2
|
Fornasier S, Mottola S, Keller HU, Barucci MA, Davidsson B, Feller C, Deshapriya JDP, Sierks H, Barbieri C, Lamy PL, Rodrigo R, Koschny D, Rickman H, A’Hearn M, Agarwal J, Bertaux JL, Bertini I, Besse S, Cremonese G, Da Deppo V, Debei S, De Cecco M, Deller J, El-Maarry MR, Fulle M, Groussin O, Gutierrez PJ, Güttler C, Hofmann M, Hviid SF, Ip WH, Jorda L, Knollenberg J, Kovacs G, Kramm R, Kührt E, Küppers M, Lara ML, Lazzarin M, Moreno JJL, Marzari F, Massironi M, Naletto G, Oklay N, Pajola M, Pommerol A, Preusker F, Scholten F, Shi X, Thomas N, Toth I, Tubiana C, Vincent JB. Rosetta’s comet 67P/Churyumov-Gerasimenko sheds its dusty mantle to reveal its icy nature. Science 2016; 354:1566-1570. [DOI: 10.1126/science.aag2671] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 10/27/2016] [Indexed: 11/03/2022]
|
3
|
|
4
|
Hässig M, Altwegg K, Balsiger H, Bar-Nun A, Berthelier JJ, Bieler A, Bochsler P, Briois C, Calmonte U, Combi M, De Keyser J, Eberhardt P, Fiethe B, Fuselier SA, Galand M, Gasc S, Gombosi TI, Hansen KC, Jäckel A, Keller HU, Kopp E, Korth A, Kührt E, Le Roy L, Mall U, Marty B, Mousis O, Neefs E, Owen T, Rème H, Rubin M, Sémon T, Tornow C, Tzou CY, Waite JH, Wurz P. Cometary science. Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko. Science 2015; 347:aaa0276. [PMID: 25613892 DOI: 10.1126/science.aaa0276] [Citation(s) in RCA: 204] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Comets contain the best-preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov-Gerasimenko with well-sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water, carbon monoxide, and carbon dioxide. These results indicate a complex coma-nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface.
Collapse
Affiliation(s)
- M Hässig
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA.
| | - K Altwegg
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Center for Space and Habitability (CSH), University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - H Balsiger
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - A Bar-Nun
- Department of Geosciences, Tel-Aviv University, Ramat-Aviv, Tel-Aviv, Israel
| | - J J Berthelier
- Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Institute Pierre Simon Laplace (IPSL), Centre national de recherche scientifique (CNRS), Université Pierre et Marie Curie (UPMC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), BP 102, UPMC, 4 Place Jussieu, F-75252 Paris Cedex 05, France
| | - A Bieler
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland. Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - P Bochsler
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - C Briois
- Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), UMR 7328 CNRS - Université d'Orléans, France
| | - U Calmonte
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - M Combi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - J De Keyser
- Belgian Institute for Space Aeronomy (BIRA-IASB), Ringlaan 3, B-1180 Brussels, Belgium. Center for Plasma Astrophysics, KULeuven, Celestijnenlaan 200D, 3001 Heverlee, Belgium
| | - P Eberhardt
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - B Fiethe
- Institute of Computer and Network Engineering (IDA), TU Braunschweig, Hans-Sommer-Straße 66, D-38106 Braunschweig, Germany
| | - S A Fuselier
- Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA
| | - M Galand
- Department of Physics, Imperial College London, Prince Consort Road, London SW7 2AZ, UK
| | - S Gasc
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - T I Gombosi
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - K C Hansen
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109, USA
| | - A Jäckel
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - H U Keller
- Institute for Geophysics and Extraterrestrial Physics, Technische Universität (TU) Braunschweig, 38106 Braunschweig, Germany. German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstraße 2, 12489 Berlin, Germany
| | - E Kopp
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - A Korth
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - E Kührt
- German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstraße 2, 12489 Berlin, Germany
| | - L Le Roy
- Center for Space and Habitability (CSH), University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - U Mall
- Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - B Marty
- Centre de Recherches Pétrographiques et Géochimiques (CRPG), 15 Rue Notre Dame des Pauvres, BP 20, 54501 Vandoeuvre lès Nancy, France
| | - O Mousis
- Aix Marseille Université, CNRS, LAM (Laboratoire d'Astrophysique de Marseille), UMR 7326, 13388, Marseille, France
| | - E Neefs
- Engineering Division, BIRA-IASB, Ringlaan 3, B-1180 Brussels, Belgium
| | - T Owen
- Institute for Astronomy, University of Hawaii, Honolulu, HI 96822, USA
| | - H Rème
- Université de Toulouse, Université Paul Sabathier (UPS), Observatoire de Midi-Pyrénées (OMP), Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France. CNRS, IRAP, 9 Avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4, France
| | - M Rubin
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - T Sémon
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - C Tornow
- German Aerospace Center, Institute of Planetary Research, Asteroids and Comets, Rutherfordstraße 2, 12489 Berlin, Germany
| | - C-Y Tzou
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - J H Waite
- Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238, USA
| | - P Wurz
- Physikalisches Institut, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| |
Collapse
|
5
|
Russell CT, Raymond CA, Coradini A, McSween HY, Zuber MT, Nathues A, De Sanctis MC, Jaumann R, Konopliv AS, Preusker F, Asmar SW, Park RS, Gaskell R, Keller HU, Mottola S, Roatsch T, Scully JEC, Smith DE, Tricarico P, Toplis MJ, Christensen UR, Feldman WC, Lawrence DJ, McCoy TJ, Prettyman TH, Reedy RC, Sykes ME, Titus TN. Dawn at Vesta: testing the protoplanetary paradigm. Science 2012; 336:684-6. [PMID: 22582253 DOI: 10.1126/science.1219381] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Dawn spacecraft targeted 4 Vesta, believed to be a remnant intact protoplanet from the earliest epoch of solar system formation, based on analyses of howardite-eucrite-diogenite (HED) meteorites that indicate a differentiated parent body. Dawn observations reveal a giant basin at Vesta's south pole, whose excavation was sufficient to produce Vesta-family asteroids (Vestoids) and HED meteorites. The spatially resolved mineralogy of the surface reflects the composition of the HED meteorites, confirming the formation of Vesta's crust by melting of a chondritic parent body. Vesta's mass, volume, and gravitational field are consistent with a core having an average radius of 107 to 113 kilometers, indicating sufficient internal melting to segregate iron. Dawn's results confirm predictions that Vesta differentiated and support its identification as the parent body of the HEDs.
Collapse
Affiliation(s)
- C T Russell
- Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Jaumann R, Williams DA, Buczkowski DL, Yingst RA, Preusker F, Hiesinger H, Schmedemann N, Kneissl T, Vincent JB, Blewett DT, Buratti BJ, Carsenty U, Denevi BW, De Sanctis MC, Garry WB, Keller HU, Kersten E, Krohn K, Li JY, Marchi S, Matz KD, McCord TB, McSween HY, Mest SC, Mittlefehldt DW, Mottola S, Nathues A, Neukum G, O’Brien DP, Pieters CM, Prettyman TH, Raymond CA, Roatsch T, Russell CT, Schenk P, Schmidt BE, Scholten F, Stephan K, Sykes MV, Tricarico P, Wagner R, Zuber MT, Sierks H. Vesta’s Shape and Morphology. Science 2012; 336:687-90. [PMID: 22582254 DOI: 10.1126/science.1219122] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- R. Jaumann
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
- Freie Universität Berlin, Planetary Sciences, Germany
| | | | - D. L. Buczkowski
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
| | - R. A. Yingst
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - F. Preusker
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - H. Hiesinger
- Westfälische Wilhelms-Universität Münster, Germany
| | | | - T. Kneissl
- Freie Universität Berlin, Planetary Sciences, Germany
| | - J. B. Vincent
- Max Planck Institute for Solar System Research (MPS), Katlenburg-Lindau, Germany
| | - D. T. Blewett
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
| | - B. J. Buratti
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - U. Carsenty
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - B. W. Denevi
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
| | - M. C. De Sanctis
- Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica (INAF), Roma, Italy
| | - W. B. Garry
- Planetary Science Institute, Tucson, AZ 85719, USA
| | | | - E. Kersten
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - K. Krohn
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - J.-Y. Li
- University of Maryland, College Park, MD 20742, USA
| | - S. Marchi
- National Aeronautics and Space Administration (NASA) Lunar Science Institute, Boulder, CO 80309, USA
| | - K. D. Matz
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | | | - H. Y. McSween
- Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, USA
| | - S. C. Mest
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - D. W. Mittlefehldt
- Astromaterials Research Office, NASA Johnson Space Center, Houston, TX 77058, USA
| | - S. Mottola
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - A. Nathues
- Max Planck Institute for Solar System Research (MPS), Katlenburg-Lindau, Germany
| | - G. Neukum
- Freie Universität Berlin, Planetary Sciences, Germany
| | | | - C. M. Pieters
- Brown University, Planetary Geosciences Department, Providence, RI 02912, USA
| | | | - C. A. Raymond
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - T. Roatsch
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - C. T. Russell
- Institute of Geophysics and Planetary Physics, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - P. Schenk
- Lunar and Planetary Institute, Houston, TX 77058, USA
| | - B. E. Schmidt
- Institute for Geophysics, University of Texas, Austin, TX 78712, USA
| | - F. Scholten
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - K. Stephan
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - M. V. Sykes
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - P. Tricarico
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - R. Wagner
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - M. T. Zuber
- Massachusetts Institute of Technology, Cambridge, MA 02139,USA
| | - H. Sierks
- Max Planck Institute for Solar System Research (MPS), Katlenburg-Lindau, Germany
| |
Collapse
|
7
|
Sierks H, Lamy P, Barbieri C, Koschny D, Rickman H, Rodrigo R, A'Hearn MF, Angrilli F, Barucci MA, Bertaux JL, Bertini I, Besse S, Carry B, Cremonese G, Da Deppo V, Davidsson B, Debei S, De Cecco M, De Leon J, Ferri F, Fornasier S, Fulle M, Hviid SF, Gaskell RW, Groussin O, Gutierrez P, Ip W, Jorda L, Kaasalainen M, Keller HU, Knollenberg J, Kramm R, Kührt E, Küppers M, Lara L, Lazzarin M, Leyrat C, Lopez Moreno JJ, Magrin S, Marchi S, Marzari F, Massironi M, Michalik H, Moissl R, Naletto G, Preusker F, Sabau L, Sabolo W, Scholten F, Snodgrass C, Thomas N, Tubiana C, Vernazza P, Vincent JB, Wenzel KP, Andert T, Pätzold M, Weiss BP. Images of asteroid 21 Lutetia: a remnant planetesimal from the early Solar System. Science 2011; 334:487-90. [PMID: 22034428 DOI: 10.1126/science.1207325] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Images obtained by the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) cameras onboard the Rosetta spacecraft reveal that asteroid 21 Lutetia has a complex geology and one of the highest asteroid densities measured so far, 3.4 ± 0.3 grams per cubic centimeter. The north pole region is covered by a thick layer of regolith, which is seen to flow in major landslides associated with albedo variation. Its geologically complex surface, ancient surface age, and high density suggest that Lutetia is most likely a primordial planetesimal. This contrasts with smaller asteroids visited by previous spacecraft, which are probably shattered bodies, fragments of larger parents, or reaccumulated rubble piles.
Collapse
Affiliation(s)
- H Sierks
- Max-Planck-Institut für Sonnensystemforschung, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Goetz W, Pike WT, Hviid SF, Madsen MB, Morris RV, Hecht MH, Staufer U, Leer K, Sykulska H, Hemmig E, Marshall J, Morookian JM, Parrat D, Vijendran S, Bos BJ, El Maarry MR, Keller HU, Kramm R, Markiewicz WJ, Drube L, Blaney D, Arvidson RE, Bell JF, Reynolds R, Smith PH, Woida P, Woida R, Tanner R. Microscopy analysis of soils at the Phoenix landing site, Mars: Classification of soil particles and description of their optical and magnetic properties. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003437] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
9
|
Sizemore HG, Mellon MT, Searls ML, Lemmon MT, Zent AP, Heet TL, Arvidson RE, Blaney DL, Keller HU. In situ analysis of ice table depth variations in the vicinity of small rocks at the Phoenix landing site. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003414] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
10
|
Keller HU, Barbieri C, Koschny D, Lamy P, Rickman H, Rodrigo R, Sierks H, A’Hearn MF, Angrilli F, Barucci MA, Bertaux JL, Cremonese G, Da Deppo V, Davidsson B, De Cecco M, Debei S, Fornasier S, Fulle M, Groussin O, Gutierrez PJ, Hviid SF, Ip WH, Jorda L, Knollenberg J, Kramm JR, Kührt E, Küppers M, Lara LM, Lazzarin M, Moreno JL, Marzari F, Michalik H, Naletto G, Sabau L, Thomas N, Wenzel KP, Bertini I, Besse S, Ferri F, Kaasalainen M, Lowry S, Marchi S, Mottola S, Sabolo W, Schröder SE, Spjuth S, Vernazza P. E-Type Asteroid (2867) Steins as Imaged by OSIRIS on Board Rosetta. Science 2010; 327:190-3. [DOI: 10.1126/science.1179559] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- H. U. Keller
- Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
| | | | - D. Koschny
- European Space and Technology Centre, Noordwijk, Netherlands
| | - P. Lamy
- Laboratoire d'Astrophysique de Marseille, Université de Provence, Marseille, France
| | - H. Rickman
- Institute för Astronomi och Rymdfysik, Uppsala, Sweden
- Polish Academy of Sciences Space Research Center, Warsaw, Poland
| | - R. Rodrigo
- Instituto de Astrofísica de Andalucía–Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - H. Sierks
- Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
| | | | | | | | - J.-L. Bertaux
- Services d’Aéronomie de CNRS, Verrières le Buisson, France
| | | | - V. Da Deppo
- Consiglio Nazionale delle Ricerche-Istituto Nazionale per la Fisica della Materia, Luxor, Padova, Italy
| | - B. Davidsson
- Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden
| | | | - S. Debei
- University of Padova, Padova, Italy
| | | | - M. Fulle
- International School for Advanced Studies, Trieste, Italy
| | - O. Groussin
- Laboratoire d'Astrophysique de Marseille, Université de Provence, Marseille, France
| | - P. J. Gutierrez
- Instituto de Astrofísica de Andalucía–Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - S. F. Hviid
- Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
| | - W.-H. Ip
- National Central University, Jhongli City, Taiwan
| | - L. Jorda
- Laboratoire d'Astrophysique de Marseille, Université de Provence, Marseille, France
| | | | - J. R. Kramm
- Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
| | - E. Kührt
- German Aerospace Center, Berlin, Germany
| | - M. Küppers
- European Space Astronomy Centre (ESAC), Madrid, Spain
| | - L.-M. Lara
- Instituto de Astrofísica de Andalucía–Consejo Superior de Investigaciones Científicas, Granada, Spain
| | | | - J. Lopez Moreno
- Instituto de Astrofísica de Andalucía–Consejo Superior de Investigaciones Científicas, Granada, Spain
| | | | - H. Michalik
- Institute of Computer and Network Engineering, Braunschweig, Germany
| | | | - L. Sabau
- Instituto Nacional de Técnica Aérospacial, Torrejon de Ardoz, Spain
| | - N. Thomas
- Physikalisches Institut der Universität Bern, Switzerland
| | - K.-P. Wenzel
- European Space and Technology Centre, Noordwijk, Netherlands
| | - I. Bertini
- Instituto de Astrofísica de Andalucía–Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - S. Besse
- Laboratoire d'Astrophysique de Marseille, Université de Provence, Marseille, France
| | - F. Ferri
- University of Padova, Padova, Italy
| | | | - S. Lowry
- University of Kent, Canterbury, UK
| | | | - S. Mottola
- German Aerospace Center, Berlin, Germany
| | - W. Sabolo
- Instituto de Astrofísica de Andalucía–Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - S. E. Schröder
- Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
| | - S. Spjuth
- Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany
| | - P. Vernazza
- European Space and Technology Centre, Noordwijk, Netherlands
| |
Collapse
|
11
|
Arvidson RE, Bonitz RG, Robinson ML, Carsten JL, Volpe RA, Trebi-Ollennu A, Mellon MT, Chu PC, Davis KR, Wilson JJ, Shaw AS, Greenberger RN, Siebach KL, Stein TC, Cull SC, Goetz W, Morris RV, Ming DW, Keller HU, Lemmon MT, Sizemore HG, Mehta M. Results from the Mars Phoenix Lander Robotic Arm experiment. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2009je003408] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
12
|
Smith PH, Tamppari LK, Arvidson RE, Bass D, Blaney D, Boynton WV, Carswell A, Catling DC, Clark BC, Duck T, Dejong E, Fisher D, Goetz W, Gunnlaugsson HP, Hecht MH, Hipkin V, Hoffman J, Hviid SF, Keller HU, Kounaves SP, Lange CF, Lemmon MT, Madsen MB, Markiewicz WJ, Marshall J, McKay CP, Mellon MT, Ming DW, Morris RV, Pike WT, Renno N, Staufer U, Stoker C, Taylor P, Whiteway JA, Zent AP. H2O at the Phoenix landing site. Science 2009; 325:58-61. [PMID: 19574383 DOI: 10.1126/science.1172339] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Phoenix mission investigated patterned ground and weather in the northern arctic region of Mars for 5 months starting 25 May 2008 (solar longitude between 76.5 degrees and 148 degrees ). A shallow ice table was uncovered by the robotic arm in the center and edge of a nearby polygon at depths of 5 to 18 centimeters. In late summer, snowfall and frost blanketed the surface at night; H(2)O ice and vapor constantly interacted with the soil. The soil was alkaline (pH = 7.7) and contained CaCO(3), aqueous minerals, and salts up to several weight percent in the indurated surface soil. Their formation likely required the presence of water.
Collapse
Affiliation(s)
- P H Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Hecht MH, Marshall J, Pike WT, Staufer U, Blaney D, Braendlin D, Gautsch S, Goetz W, Hidber HR, Keller HU, Markiewicz WJ, Mazer A, Meloy TP, Morookian JM, Mogensen C, Parrat D, Smith P, Sykulska H, Tanner RJ, Reynolds RO, Tonin A, Vijendran S, Weilert M, Woida PM. Microscopy capabilities of the Microscopy, Electrochemistry, and Conductivity Analyzer. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008je003077] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
14
|
Inada A, Garcia-Comas M, Altieri F, Gwinner K, Poulet F, Bellucci G, Keller HU, Markiewicz WJ, Richardson MI, Hoekzema N, Neukum G, Bibring JP. Dust haze in Valles Marineris observed by HRSC and OMEGA on board Mars Express. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007je002893] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
15
|
Markiewicz WJ, Titov DV, Limaye SS, Keller HU, Ignatiev N, Jaumann R, Thomas N, Michalik H, Moissl R, Russo P. Morphology and dynamics of the upper cloud layer of Venus. Nature 2007; 450:633-6. [DOI: 10.1038/nature06320] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 09/20/2007] [Indexed: 11/09/2022]
|
16
|
Tomasko MG, Archinal B, Becker T, Bézard B, Bushroe M, Combes M, Cook D, Coustenis A, de Bergh C, Dafoe LE, Doose L, Douté S, Eibl A, Engel S, Gliem F, Grieger B, Holso K, Howington-Kraus E, Karkoschka E, Keller HU, Kirk R, Kramm R, Küppers M, Lanagan P, Lellouch E, Lemmon M, Lunine J, McFarlane E, Moores J, Prout GM, Rizk B, Rosiek M, Rueffer P, Schröder SE, Schmitt B, See C, Smith P, Soderblom L, Thomas N, West R. Rain, winds and haze during the Huygens probe's descent to Titan's surface. Nature 2005; 438:765-78. [PMID: 16319829 DOI: 10.1038/nature04126] [Citation(s) in RCA: 466] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Accepted: 08/08/2005] [Indexed: 11/09/2022]
Abstract
The irreversible conversion of methane into higher hydrocarbons in Titan's stratosphere implies a surface or subsurface methane reservoir. Recent measurements from the cameras aboard the Cassini orbiter fail to see a global reservoir, but the methane and smog in Titan's atmosphere impedes the search for hydrocarbons on the surface. Here we report spectra and high-resolution images obtained by the Huygens Probe Descent Imager/Spectral Radiometer instrument in Titan's atmosphere. Although these images do not show liquid hydrocarbon pools on the surface, they do reveal the traces of once flowing liquid. Surprisingly like Earth, the brighter highland regions show complex systems draining into flat, dark lowlands. Images taken after landing are of a dry riverbed. The infrared reflectance spectrum measured for the surface is unlike any other in the Solar System; there is a red slope in the optical range that is consistent with an organic material such as tholins, and absorption from water ice is seen. However, a blue slope in the near-infrared suggests another, unknown constituent. The number density of haze particles increases by a factor of just a few from an altitude of 150 km to the surface, with no clear space below the tropopause. The methane relative humidity near the surface is 50 per cent.
Collapse
Affiliation(s)
- M G Tomasko
- Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd, Tucson, Arizona 85721-0092, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Dehghani Zadeh A, Seveau S, Halbwachs-Mecarelli L, Keller HU. Chemotactically-induced redistribution of CD43 as related to polarity and locomotion of human polymorphonuclear leucocytes. Biol Cell 2003; 95:265-73. [PMID: 12941524 DOI: 10.1016/s0248-4900(03)00053-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Leukocyte motility involves pseudopods extension at the leading edge and uropod contraction at the cell rear. Previous studies have shown that the glycoprotein CD43 redistributes to the uropod, when the cells develop polarity and locomotion. The present study addresses the question whether the accumulation of specific membrane molecules, such as CD43 at the contracted uropod precedes or follows development of polarity and locomotion. PMNs were labeled with fluorescent anti-CD43 antibodies and guided to polarize in the direction of a chemoattractant-containing micropipette or, once polarized, they were forced to reverse polarity and movement direction by placing the micropipette behind the uropod. This chemotactically-induced reversal of polarity was used as an efficient tool to analyse the sequence of events. CD43, but not another abundant surface glycoprotein CD45, was concentrated at the uropod. This documents that CD43 redistribution is a selective phenomenon. During reversal of polarity and of locomotion direction, the geometric center of the cell clearly changed direction earlier than the center of anti-CD43 fluorescence intensity. Thus, CD43 redistribution to the new uropod follows rather than precedes reversal of polarity, suggesting that CD43 redistribution is a consequence rather than a prerequisite for polarity and locomotion. PMNs making a U-turn maintained the pre-existing polarity and CD43 remained concentrated at the uropod, even when the front was moving in the opposite direction. Our data show that anterior pseudopod formation, rather than capping of CD43 at the uropod or the position of the uropod determines the direction of locomotion.
Collapse
Affiliation(s)
- A Dehghani Zadeh
- Institute of Pathology, University of Bern, 3010 Bern, Switzerland.
| | | | | | | |
Collapse
|
18
|
Sroka J, von Gunten M, Dunn GA, Keller HU. Phenotype modulation in non-adherent and adherent sublines of Walker carcinosarcoma cells: the role of cell-substratum contacts and microtubules in controlling cell shape, locomotion and cytoskeletal structure. Int J Biochem Cell Biol 2002; 34:882-99. [PMID: 11950602 DOI: 10.1016/s1357-2725(01)00178-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We characterised two sublines of Walker carcinosarcoma cells generated by epigenetic changes. Subline 1 cells were mostly polarised and made no or only non-adhesive cell-substratum contacts. Subline 2 cells were spread, adhesive and mainly non-polar. Subline 1 cells migrate in a non-adhesive mode which is very efficient but operates only in a 3D environment, whereas subline 2 cells migrate in an adhesive mode, which is less efficient but works on 2D and 3D substrata. Nocodazole had little or no effect on shape, polarity and locomotion of subline 1 cells. In glass-adherent subline 2 cells, 10(-6)M nocodazole increased the proportion of polarised cells migrating in an adhesive mode and decreased adhesion to the substratum, whereas 10(-5)M nocodazole further reduced the contacts and the cells reverted to a non-adhesive mode of locomotion. When non-polar subline 2 cells were detached mechanically or by nocodazole, they became polarised and morphologically indistinguishable from non-adherent subline 1 cells. On more adhesive plastic substrata, subline 2 cells produced heterogeneous responses to nocodazole including loss of polarity. The phenotypes of Walker carcinosarcoma sublines have similarities with a broad range of cell types ranging from leucocytes to fibroblast-like cells, suggesting that these phenotypic differences can be controlled by the adhesive and contractile state rather than the cell type. Adhesion modulates contractility (isometric or isotonic contraction) and vice versa and this determines morphology (shape, F-actin, myosin and alpha-actinin), locomotion and responses to microtubule-disassembly. The model may be applied to analyse the mechanisms controlling the phenotype of cells in general.
Collapse
Affiliation(s)
- J Sroka
- Institute of Pathology, University of Bern, Murtenstrasse 31, 3010, Bern, Switzerland
| | | | | | | |
Collapse
|
19
|
Smith PH, Reynolds R, Weinberg J, Friedman T, Lemmon MT, Tanner R, Reid RJ, Marcialis RL, Bos BJ, Oquest C, Keller HU, Markiewicz WJ, Kramm R, Gliem F, Rueffer P. The MVACS Surface Stereo Imager on Mars Polar Lander. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999je001116] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
20
|
Keller HU, Hartwig H, Kramm R, Koschny D, Markiewicz WJ, Thomas N, Fernades M, Smith PH, Reynolds R, Lemmon MT, Weinberg J, Marcialis R, Tanner R, Boss BJ, Oquest C, Paige DA. The MVACS Robotic Arm Camera. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/1999je001123] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
21
|
Urwyler N, Eggli P, Keller HU. Effects of the myosin inhibitor 2,3-butanedione monoxime (BDM) on cell shape, locomotion and fluid pinocytosis in human polymorphonuclear leucocytes. Cell Biol Int 2001; 24:863-70. [PMID: 11114235 DOI: 10.1006/cbir.2000.0579] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the role of myosin in polymorphonuclear leucocyte (PMN) shape changes, locomotion, and fluid pinocytosis using the myosin inhibitor 2,3 butanedione monoxime (BDM). Treatment of resting spherical PMNs with BDM produced spheroid cells showing small continuous shape changes (IC(50)=15.5 m m BDM) and occasionally small blebs. Cell polarity, as induced by the chemotactic peptide fNLPNTL or by colchicine, and locomotion were completely suppressed (IC(50)=8.4 to 10 m m). Suppression of fNLPNTL- or colchicine-induced cell polarity produced spheroid cells, suppression of PMA-induced shape changes and fluid pinocytosis produced non-motile spherical cells (IC(50)=25 to 30 m m BDM). BDM suppressed formation of lamellipodia but not formation of blebs. Suppression of microvilli by BDM as observed in resting spherical cells was partially antagonized by PMA. The results suggest that myosin is involved in stabilizing the shape of resting spherical cells, including microvilli, and that myosin is required for cell polarity, locomotion, fluid pinocytosis and for formation of lamellipodia, but not for formation of blebs.
Collapse
Affiliation(s)
- N Urwyler
- Institute of Pathology, University of Bern, Bern, Switzerland
| | | | | |
Collapse
|
22
|
Abstract
The role of protein kinase C (PKC) isoforms in the regulation of cell shape [switch between fibroblast-like and crescent shape (CS)] and of locomotion of human fibrosarcoma HT1080 cells has been investigated. The PKC activator phorbol myristate acetate (PMA) induced the transition of elongated fibroblast-like cells into CS cells and stimulated locomotion. Both responses to PMA were inhibited by the PKC inhibitor Ro 31-8220. Analysis of the time course showed that stimulation of shape changes (formation of CS cells) and locomotor activity (increase in the proportion and speed of locomoting cells) was maximal in the early phase of the response (up to 2.5 hr) and significantly decreased later (15 to 21 hr). CS formation and stimulated locomotion correlated closely with a marked redistribution from the cytosol to the membrane of PKC isoforms alpha, beta1 and gamma in the early phase (0.5 to 2 hr) following activation with PMA. The subsequent reduction of the proportion of CS cells and of cell locomotion correlated with down-regulation of these isoforms in the second phase (16 to 21 hr). In contrast, the total amount and distribution of PKC beta2 remained almost unchanged with 10(-8) M PMA up to 21 hr. Furthermore, changes in shape and locomotion did not correlate with the responses of PKC delta to PMA. Inhibition of PMA-stimulated locomotion by the more specific inhibitor Gö 6976 is consistent with a role of PKC alpha and beta1 in this response. Ro 31-8220 alone induced a moderate down-regulation of PKC isoforms alpha and delta, but it also inhibited the more pronounced down-regulation of these isoforms by PMA. Our results indicate that activation of PKC isoforms alpha, gamma and beta1, but not beta2 or delta, stimulates locomotion and formation of CS cells in human fibrosarcoma HT1080 cells.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Bern, Switzerland.
| | | | | | | | | |
Collapse
|
23
|
Blum J, Wurm G, Kempf S, Poppe T, Klahr H, Kozasa T, Rott M, Henning T, Dorschner J, Schräpler R, Keller HU, Markiewicz WJ, Mann I, Gustafson BA, Giovane F, Neuhaus D, Fechtig H, Grün E, Feuerbacher B, Kochan H, Ratke L, El Goresy A, Morfill G, Weidenschilling SJ, Schwehm G, Metzler K, Ip WH. Growth and form of planetary seedlings: results from a microgravity aggregation experiment. Phys Rev Lett 2000; 85:2426-2429. [PMID: 10978073 DOI: 10.1103/physrevlett.85.2426] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2000] [Indexed: 05/23/2023]
Abstract
The outcome of the first stage of planetary formation, which is characterized by ballistic agglomeration of preplanetary dust grains due to Brownian motion in the free molecular flow regime of the solar nebula, is still somewhat speculative. We performed a microgravity experiment flown onboard the space shuttle in which we simulated, for the first time, the onset of free preplanetary dust accumulation and revealed the structures and growth rates of the first dust agglomerates in the young solar system. We find that a thermally aggregating swarm of dust particles evolves very rapidly and forms unexpected open-structured agglomerates.
Collapse
Affiliation(s)
- J Blum
- Astrophysical Institute and University Observatory, University of Jena, Schillergässchen 2-3, 07745 Jena, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Abstract
Locomoting metazoan cells usually form lamellipodia at the leading front and it is widely accepted that lamellipodia are required for locomotion. In this case, suppression of lamellipodia must stop locomotion. However, the experiments show that lamellipodia are redundant for locomotion of Walker carcinosarcoma cells. Low latrunculin A concentrations (10(-7) M) transform polarised locomoting cells with lamellipodia into cells without morphologically recognisable protrusions showing an increased speed of locomotion and a reduced amount of cellular F-actin. Whereas untreated cells show a fairly linear distribution of F-actin along the plasma membrane, cells lacking morphologically recognizable protrusions at the front show modifications at the front consisting in an irregular distribution of F-actin with formation of small or large patches of F-actin alternating with small or large gaps in the F-actin layer. This is associated with a reduced resistance to deformation pressure at the front of the cell. High concentrations of latrunculin A (>10(-7) M) compromising contraction at the rear stop locomotion, suggesting that cortical contraction is important for locomotion to occur in these cells. The results are consistent with the view that actin polymerization is important for formation of lamellipodia but they are not compatible with the view that lamellipodia are essential for locomotion of Walker carcinosarcoma cells. A unifying hypothesis for the formation of different types of protrusions is proposed.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Bern, Switzerland.
| |
Collapse
|
25
|
Fedier A, Keller HU. Suppression of bleb formation, locomotion, and polarity of Walker carcinosarcoma cells by hypertonic media correlates with cell volume reduction but not with changes in the F-actin content. Cell Motil Cytoskeleton 2000; 37:326-37. [PMID: 9258505 DOI: 10.1002/(sici)1097-0169(1997)37:4<326::aid-cm4>3.0.co;2-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The putative role of cellular or solvent volume in protrusive activity and locomotion has been investigated in blebbing Walker carcinosarcoma cells using hypertonic media. Blebbing, locomotion, and cell polarity are completely suppressed by 0.2 M sorbitol. The response occurs in two steps. In a first step, i.e. within 10 sec after the addition of sorbitol, blebbing and locomotion are inhibited and this is associated with an average cell volume reduction by 17% (corresponding to a reduction in solvent volume by 38%). It clearly precedes suppression of cell polarity (pre-existing protrusions, tail) occurring in a second step within 5 to 10 min after addition of sorbitol without additional reduction in the cell or solvent volume. The relative amount of F-actin does not correlate with the decrease in cell volume, suppression of blebbing, locomotion, and cell polarity. A significant decrease in the relative amount of F-actin is found only at volume reductions which are higher than those required to completely suppress blebbing, locomotion, and cell polarity. F-actin staining occurs preferentially along the cell membrane in isotonic as well as in hypertonic media. The results are best compatible with the hypothesis that hydrostatic pressure rather than actin polymerization at the front is the direct force driving the membrane forward during bleb formation. Cells with lamellipodia show a similar response to hypertonic media, suggesting that basically similar mechanisms may operate in both forms of protrusions.
Collapse
Affiliation(s)
- A Fedier
- Institute of Pathology, University of Bern, Switzerland
| | | |
Collapse
|
26
|
Abstract
Capping in cells developing polarity has been reinterpreted on the basis of a quantitative analysis of Concanavalin A (Con A) redistribution and cell movement in Walker carcinosarcoma cells. Several new features emerged. Based on the developing asymmetry in the distribution of surface-bound Con A, the direction of cell movement and the prospective front-tail polarity can already be predicted when the cell is spherical. Development of polarity by an initially spherical cell is associated with formation of two parts. The concentrically contracting part (prospective uropod) characterized by surface-associated Con A decreases in size, while the other part is cleared from Con A and grows into formerly unoccupied space. Surface-bound Con A shows isotropic centripetal movement towards the initial position of the centroid of the spherical cell rather than rearward movement. Therefore, the centroid of fluorescence intensity remains either stationary or moves marginally forward with respect to the initial position of the spherical cell. The amount and direction of cell movement measured correlates closely with values predicted by a theoretical model that assumes a unidirectional transfer of volume from a stationary contracting compartment into a protruding compartment. The results suggest that isotropic (cortical) contraction of the initially spherical cells and one-sided relaxation rather than unidirectional retrograde movement of ligand-receptor complexes produces movement in cells developing polarity. Reversible accumulation of surface-bound Con A at the uropod occurring to a similar extent in untreated and colchicine-treated cells is partly due to membrane folding and partly to movement in the plane of the membrane.
Collapse
Affiliation(s)
- A Fedier
- Institute of Pathology, University of Bern, Bern, Switzerland
| | | | | |
Collapse
|
27
|
Golombek MP, Anderson RC, Barnes JR, Bell JF, Bridges NT, Britt DT, Brückner J, Cook RA, Crisp D, Crisp JA, Economou T, Folkner WM, Greeley R, Haberle RM, Hargraves RB, Harris JA, Haldemann AFC, Herkenhoff KE, Hviid SF, Jaumann R, Johnson JR, Kallemeyn PH, Keller HU, Kirk RL, Knudsen JM, Larsen S, Lemmon MT, Madsen MB, Magalhães JA, Maki JN, Malin MC, Manning RM, Matijevic J, McSween HY, Moore HJ, Murchie SL, Murphy JR, Parker TJ, Rieder R, Rivellini TP, Schofield JT, Seiff A, Singer RB, Smith PH, Soderblom LA, Spencer DA, Stoker CR, Sullivan R, Thomas N, Thurman SW, Tomasko MG, Vaughan RM, Wänke H, Ward AW, Wilson GR. Overview of the Mars Pathfinder Mission: Launch through landing, surface operations, data sets, and science results. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/98je02554] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
28
|
Thomas N, Britt DT, Herkenhoff KE, Murchie SL, Semenov B, Keller HU, Smith PH. Observations of Phobos, Deimos, and bright stars with the Imager for Mars Pathfinder. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/98je02555] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
29
|
Basilevsky AT, Markiewicz WJ, Thomas N, Keller HU. Morphologies of rocks within and near the Rock Garden at the Mars Pathfinder landing site. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1998je900039] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
30
|
Thomas N, Markiewicz WJ, Sablotny RM, Wuttke MW, Keller HU, Johnson JR, Reid RJ, Smith PH. The color of the Martian sky and its influence on the illumination of the Martian surface. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/98je02556] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
31
|
Titov DV, Markiewicz WJ, Thomas N, Keller HU, Sablotny RM, Tomasko MG, Lemmon MT, Smith PH. Measurements of the atmospheric water vapor on Mars by the Imager for Mars Pathfinder. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1998je900046] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
32
|
Markiewicz WJ, Sablotny RM, Keller HU, Thomas N, Titov D, Smith PH. Optical properties of the Martian aerosols as derived from Imager for Mars Pathfinder midday sky brightness data. ACTA ACUST UNITED AC 1999. [DOI: 10.1029/1998je900033] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
33
|
Sims MR, Pillinger CT, Wright IP, Dowson J, Whitehead S, Wells A, Spragg JE, Fraser G, Richter L, Hamacher H, Johnstone A, Meredith NP, de la Nougerede C, Hancock B, Turner R, Peskett S, Brack A, Hobbs J, Newns M, Senior A, Humphries M, Keller HU, Thomas N, Lingard JS, Ng TC. Beagle 2: a proposed exobiology lander for ESA's 2003 Mars Express mission. Adv Space Res 1999; 23:1925-1928. [PMID: 11543221 DOI: 10.1016/s0273-1177(99)00280-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The aim of the proposed Beagle 2 small lander for ESA's 2003 Mars Express mission is to search for organic material on and below the surface of Mars and to study the inorganic chemistry and mineralogy of the landing site. The lander will have a total mass of 60kg including entry, descent, and landing system. Experiments will be deployed on the surface using a robotic arm. It will use a mechanical mole and grinder to obtain samples from below the surface, under rocks, and inside rocks. Sample analysis by a mass spectrometer will include isotopic analysis. An optical microscope, an X-ray spectrometer and a Mossbauer spectrometer will conduct in-situ rock studies.
Collapse
Affiliation(s)
- M R Sims
- Space Research Centre, University of Leicester, UK
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Smith PH, Bell JF, Bridges NT, Britt DT, Gaddis L, Greeley R, Keller HU, Herkenhoff KE, Jaumann R, Johnson JR, Kirk RL, Lemmon M, Maki JN, Malin MC, Murchie SL, Oberst J, Parker TJ, Reid RJ, Sablotny R, Soderblom LA, Stoker C, Sullivan R, Thomas N, Tomasko MG, Wegryn E. Results from the Mars Pathfinder camera. Science 1997; 278:1758-65. [PMID: 9388170 DOI: 10.1126/science.278.5344.1758] [Citation(s) in RCA: 204] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Images of the martian surface returned by the Imager for Mars Pathfinder (IMP) show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial, aeolian, and impact processes. Analysis of the spectral signatures in the scene (at 440- to 1000-nanometer wavelength) reveal three types of rock and four classes of soil. Upward-looking IMP images of the predawn sky show thin, bluish clouds that probably represent water ice forming on local atmospheric haze (opacity approximately 0.5). Haze particles are about 1 micrometer in radius and the water vapor column abundance is about 10 precipitable micrometers.
Collapse
Affiliation(s)
- P H Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Crovisier J, Leech K, Bockelée-Morvan D, Brooke TY, Hanner MS, Altieri B, Keller HU, Lellouch E. The spectrum of comet Hale-Bopp (C/1995 O1) observed with the Infrared Space Observatory at 2.9 astronomical units from the sun. Science 1997; 275:1904-7. [PMID: 9072960 DOI: 10.1126/science.275.5308.1904] [Citation(s) in RCA: 405] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Comet Hale-Bopp (C/1995 O1) was observed at wavelengths from 2.4 to 195 micrometers with the Infrared Space Observatory when the comet was about 2.9 astronomical units (AU) from the sun. The main observed volatiles that sublimated from the nucleus ices were water, carbon monoxide, and carbon dioxide in a ratio (by number) of 10:6:2. These species are also the main observed constituents of ices in dense interstellar molecular clouds; this observation strengthens the links between cometary and interstellar material. Several broad emission features observed in the 7- to 45-micrometer region suggest the presence of silicates, particularly magnesium-rich crystalline olivine. These features are similar to those observed in the dust envelopes of Vega-type stars.
Collapse
Affiliation(s)
- J Crovisier
- Observatoire de Paris-Meudon, F-92195 Meudon, France
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Smith PH, Tomasko MG, Britt D, Crowe DG, Reid R, Keller HU, Thomas N, Gliem F, Rueffer P, Sullivan R, Greeley R, Knudsen JM, Madsen MB, Gunnlaugsson HP, Hviid SF, Goetz W, Soderblom LA, Gaddis L, Kirk R. The imager for Mars Pathfinder experiment. ACTA ACUST UNITED AC 1997. [DOI: 10.1029/96je03568] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
37
|
Abstract
Locomoting blebbing cells have been used as a model to obtain novel insight into the mechanisms of cell locomotion. We tested the hypothesis that locomotion can be due to progressive one-sided protrusion of cellular volume into pseudopods. The hypothesis is supported by the finding that the rate and direction of locomotion of individual Walker carcinosarcoma cells can be predicted by sequential measurement of protrusive activity. Protrusive activity at the front is closely associated with forward movement of the rear part of the cell. During bleb formation the cell membrane of Walker carcinosarcoma cells is pushed forward faster (1.2-4.1 microns/sec) than known rates of actin elongation.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Switzerland
| | | |
Collapse
|
38
|
Keller HU, Fedier A, Rohner R. Relationship between light scattering in flow cytometry and changes in shape, volume, and actin polymerization in human polymorphonuclear leukocytes. J Leukoc Biol 1995; 58:519-25. [PMID: 7595052 DOI: 10.1002/jlb.58.5.519] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Using two different cytometers, an Epics Profile II and a FACScan, we determined the extent to which changes in forward and right angle scatter are a reliable measure for changes in polymorphonuclear leukocyte (PMN) shape, volume, and actin polymerization and whether distinct types of shape changes in PMNs can be recognized. PMN stimulation can substantially change the positions of PMNs in the scatter diagram of the FACScan but not of the Epics Profile II. Within the limits of the experiments, it has been possible to determine whether or not a shape change has taken place using the FACScan but not using the Epics Profile II. However, using either cytometer, it has not been possible to determine which type of shape change (e.g., spherical vs. polarized vs. nonpolar cells) has taken place. Furthermore, forward or right angle scatter changes are not a reliable measure for changes in cell volume or actin polymerization of human PMNs.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Switzerland
| | | | | |
Collapse
|
39
|
Trachsel S, Keller HU. Selective responses (actin polymerization, shape changes, locomotion, pinocytosis) to the PKC inhibitor Ro 31-8220 suggest that PKC discriminately regulates functions of human blood lymphocytes. J Leukoc Biol 1995; 57:587-91. [PMID: 7536787 DOI: 10.1002/jlb.57.4.587] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The results suggest that protein kinase C (PKC) plays a pivotal role in the control of F-actin levels, locomotion, pinocytosis, and cell shape in lymphocytes. The PKC inhibitor Ro 31-8220 elicits a high proportion of polarized (ED50 = 1.5 x 10(-6) M) and locomoting cells and reduces the relative amount of F-actin (by 29% at 10(-5) M) in initially resting cells. Phorbol myristate acetate (PMA) counterbalances the polarizing effect of Ro 31-8220. This indicates that the spherical shape and the F-actin content of resting cells are maintained by constitutive PKC activity. PMA-induced increases in fluid pinocytosis, F-actin content, and formation of nonpolar cells with surface protrusion are suppressed by Ro 31-8220 (IC50 = 2-4 x 10(-7) M). Spherical cells and, at higher concentrations (ED50 = 3.3 x 10(-6) M), polarized cells are formed instead. As a result, lymphocyte function switches from fluid pinocytosis to cell polarity and locomotion. The data indicate that PKC is instrumental in selectively switching lymphocyte function between resting state, locomotor activity, and fluid pinocytosis. Ro 31-8220 is extremely potent in stimulating lymphocyte polarity and locomotion (B and T cells). It acts faster and/or produces a higher proportion of polarized lymphocytes than other available agonists. It may thus be used as a tool in further experiments requiring locomoting lymphocytes.
Collapse
Affiliation(s)
- S Trachsel
- Institute of Pathology, University of Bern, Switzerland
| | | |
Collapse
|
40
|
Abstract
Using two newly synthesized inhibitors, Ro 31-8220 and CGP 41,251, of protein kinase C (PKC), we analysed: (1) how distinct PMN functions (shape changes, locomotion, pinocytosis) are regulated, and (2) the role of protein phosphorylation and PKC in this process. We were able to transform: (1) resting PMNs into locomoting cells using fNLPNTL, (2) locomoting cells into non-locomoting highly pinocytic cells using PMA, and (3) PMA-stimulated cells showing marked pinocytosis into locomoting or into resting cells using Ro 31-8220. It is thus possible to selectively manipulate PMN function (resting state, locomotion, marked pinocytosis), indicating that there are different regulatory pathways. It was not possible to induce locomotion and marked pinocytosis simultaneously, indicating crosstalk between pathways. Ro 31-8220 inhibited PMA-induced shape changes (nonpolar cells) and pinocytosis, but not fNLPNTL-induced shape changes (polarity) and pinocytosis. At higher concentrations, Ro 31-8220 alone elicited cell polarity and chemokinesis, indicating that a constitutively active protein kinase is involved in maintaining the spherical shape of resting PMNs. Functional effects of another PKC inhibitor, CGP 41,251, on neutrophil function were strikingly different. CGP 41,251 selectively inhibited fNLPNTL-induced polarity and locomotion (but not colchicine or Ro 31-8220-induced polarity), and it failed to inhibit PMA-induced, stimulated pinocytosis and shape changes. Although the effects of Ro 31-8220 vs. CGP 41,251 on PMN function were strikingly different, the inhibition of profiles for constitutive and for fNLPNTL- or PMA-induced protein phosphorylation in intact PMNs showed only small differences, which could not yet be conclusively related to cell function.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Switzerland
| | | |
Collapse
|
41
|
Keller HU, Niggli V. The PKC-inhibitor Ro 31-8220 selectively suppresses PMA- and diacylglycerol-induced fluid pinocytosis and actin polymerization in PMNs. Biochem Biophys Res Commun 1993; 194:1111-6. [PMID: 8352766 DOI: 10.1006/bbrc.1993.1936] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The PKC-inhibitor Ro 31-8220 inhibits stimulated fluid pinocytosis of human PMNs induced by the PKC-activators phorbol myristate acetate (PMA, IC50 = 1.35 x 10(-6) M) or diacylglycerols (OAG, diC8) by 95%, whereas Ro 31-8220 has no effect on D2O- or fNLPNTL-induced pinocytosis and enhances cytochalasin D- induced pinocytosis. Also formation of F-actin induced by PMA or diacylglycerols is selectively inhibited. The results indicate that a Ro 31-8220 -sensitive PKC is involved in signal transduction for enhanced pinocytosis and F-actin formation in response to one class of stimuli (classical activators of PKC) but not to others.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Switzerland
| | | |
Collapse
|
42
|
McDonnell JAM, McBride N, Beard R, Bussoletti E, Colangeli L, Eberhardt P, Firth JG, Grard R, Green SF, Greenberg JM, Grün E, Hughes DW, Keller HU, Kissel J, Lindblad BA, Mandeville JC, Perry CH, Rembor K, Rickman H, Schwehm GH, Turner RF, Wallis MK, Zarnecki JC. Dust particle impacts during the Giotto encounter with comet Grigg–Skjellerup. Nature 1993. [DOI: 10.1038/362732a0] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
43
|
Keller HU, Niggli V. Colchicine-induced stimulation of PMN motility related to cytoskeletal changes in actin, alpha-actinin, and myosin. Cell Motil Cytoskeleton 1993; 25:10-8. [PMID: 8519064 DOI: 10.1002/cm.970250103] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Colchicine-induced stimulation of polymorphonuclear leukocyte (PMN) locomotion is an interesting model because extension of blebs at the front occurs at a rate (about 2.4 microns/s) which is far above that reported for growth of actin filaments. The following cytoskeletal changes were observed in colchicine-treated PMNs: (1) a small increase in cytoskeleton-associated actin was noted, as well as a somewhat more pronounced increase in cytoskeleton-associated alpha-actinin, as compared with untreated or DMSO-treated controls. There was, however, no measurable increase in F-actin as determined by NBD-phallacidin binding; (2) the values for the ratio (alpha-actinin/actin) are lower in PMNs treated with colchicine for 30 min, as compared with PMNs stimulated with fNLPNTL for 1 minute (non-polar ruffling cells) or 30 min (polarized locomoting cells); thus, this ratio may depend on the type of PMN motility; (3) in polarized PMNs F-actin was mainly located linearly all along the cell membrane; there was more intense staining at the front of the cells; (4) alpha-actinin appeared to colocalize with F-actin at the leading front, but not with F-actin at the tail of polarized cells; (5) myosin was preferentially found at the rear part of polarized cells but not or only to a small extent at the front. Our data indicate a close functional correlation between microtubules and microfilaments. We speculate that F-actin in combination with alpha-actinin promotes expansion of pseudopods, whereas myosin combined with F-actin promotes contraction.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Switzerland
| | | |
Collapse
|
44
|
Riede UN, Zeck-Kapp G, Freudenberg N, Keller HU, Seubert B. Humate-induced activation of human granulocytes. Virchows Arch B Cell Pathol Incl Mol Pathol 1991; 60:27-34. [PMID: 1673274 DOI: 10.1007/bf02899524] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Naturally occurring humic substances are particular chemical compounds which are found in humus. They bind to carbohydrates, amino acids and steroids by means of hydrogen bonds, covalent bonds and epsilon donor-acceptor complexes. Three specimens of low-molecular humic substances were tested (two naturally occurring humates and one synthetically prepared humate). They were all capable of stimulating certain functions of human neutrophils (PMN), such as the respiratory burst which results in the production of toxic oxygen compounds. This PMN stimulation can be demonstrated with the help of chemiluminescence, as well as by cytochemistry and with the electron microscope. The main product of the humate-induced PMN response is H2O2. There was no activation of neutrophilic chemokinesis or chemotaxis. It is suggested that the low-molecular humic substances originating from decaying organic material contain chemical structures which can act as signals to change dormant PMN into activated cells.
Collapse
Affiliation(s)
- U N Riede
- Department of Pathology, University of Freiburg, Federal Republic of Germany
| | | | | | | | | |
Collapse
|
45
|
Eisele S, Lackie JM, Riedwyl H, Zimmermann A, Keller HU. Analysis of lymphocyte shape by visual classification, calculated measures of shape or light scattering. J Immunol Methods 1991; 138:103-9. [PMID: 2019739 DOI: 10.1016/0022-1759(91)90069-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Direct visual assays, calculated measures of shape (Dunn and Brown, 1986) and light scattering were applied to detect shape changes and to identify human peripheral blood lymphocytes displaying different shapes (e.g., spherical cells, polarized cells, non-polar cells with surface projections). Spherical cells could be distinguished from polarized cells and from non-polar cells with surface projections by means of calculated measures of shape obtained from outline drawings, the dispersion parameter being more efficient than extension or elongation parameters. Median values for elongation and extension of polarized cells vs. non-polar cells with surface projections differed significantly provided the cell populations consisted entirely of one particular morphological class. However, if the proportion of cells changing shape is small, this may not be detectable by a significant change in the median values. Therefore, we attempted to apply calculated shape factors to identify individual cells showing a particular type of shape change. Spherical cells could be distinguished relatively easily from non-spherical cells on the basis of the dispersion values. However, it was not possible to distinguish unequivocally between polarized cells and non-polar cells with surface projections because the values overlap to a great extent. For this purpose the visual classification was found to be more reliable. Preliminary experiments with light scattering showed that median values for right angle scatter or forward angle scatter are not sensitive enough to permit the detection of a small proportion of cells changing shape.
Collapse
Affiliation(s)
- S Eisele
- Institute of Pathology, University of Bern, Switzerland
| | | | | | | | | |
Collapse
|
46
|
Abstract
Diacylglycerols (OAG, diC8) and PMA were found to stimulate fluid pinocytosis (net uptake of FITC-dextran) to a far greater extent than other neutrophil activators, such as the chemotactic agents fNLPNTL and LTB4, the microtubule disassembling agents colchicine and nocodazole, the kinase inhibitor H-7, or D2O. OAG and diC8 produce a dose-dependent increase in the uptake of FITC-dextran, which is up to about 25- to 30-fold the control value of unstimulated neutrophils. The protein kinase inhibitor H-7 alone had a small stimulating effect on the net uptake, and it failed to inhibit stimulation of fluid pinocytosis by PMA, OAG, and diC8. Also, the protein kinase inhibitor staurosporine failed to inhibit fluid pinocytosis stimulated by OAG, diC8, and PMA. Stimulated fluid pinocytosis and vacuolization in response to PMA or diacylglycerols is associated with surface ruffling of neutrophils. Pinocytosis as well as surface ruffling stimulated by PMA, OAG, diC8, or diC10 are suppressed in the presence of cytochalasin D. The results suggest that diacylglycerols may be instrumental in transducing the signal for stimulated pinocytosis and that the surface movements induced by diacylglycerols, and PMA may be instrumental in fluid pinocytosis.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, Bern, Switzerland
| |
Collapse
|
47
|
Keller R, Keist R, Erb P, Aebischer T, De Libero G, Balzer M, Groscurth P, Keller HU. Expression of cellular effector functions and production of reactive nitrogen intermediates: a comparative study including T lymphocytes, T-like cells, neutrophil granulocytes, and mononuclear phagocytes. Cell Immunol 1990; 131:398-403. [PMID: 2242503 DOI: 10.1016/0008-8749(90)90264-r] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The ability of various cell types to secrete reactive nitrogen intermediates (RNI) upon functional activation was comparatively assessed. Neither in T lymphocyte clones mediating MHC class I or class II antigen-restricted killing via alpha/beta T cell receptor (TcR) or MHC-unrestricted killing via gamma/delta TcR, nor in peripheral blood mononuclear cells expressing natural killer or lymphokine-activated killer activity, target cell lysis was associated with detectable RNI production. Also, activated neutrophil granulocytes did not secrete RNI. In contrast, bone marrow-derived mononuclear phagocytes, activated to express tumoricidal activity, secreted marked RNI activity.
Collapse
Affiliation(s)
- R Keller
- Institute for Immunology and Virology, University of Zurich, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
48
|
Keller HU, Niggli V, Zimmermann A, Portmann R. The protein kinase C inhibitor H-7 activates human neutrophils: effect on shape, actin polymerization, fluid pinocytosis and locomotion. J Cell Sci 1990; 96 ( Pt 1):99-106. [PMID: 1695636 DOI: 10.1242/jcs.96.1.99] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The present study demonstrates new properties of H-7. The protein kinase inhibitor H-7 is a potent activator of several neutrophil functions. Stimulation of initially spherical nonmotile neutrophils elicits vigorous shape changes within a few seconds, increases in cytoskeletal actin, altered F-actin distribution, increased adhesiveness and a relatively small increase in pinocytic activity. H-7 has also chemokinetic activities. Depending on the experimental condition, H-7 may elicit or inhibit neutrophil locomotion. It failed to induce chemotaxis. Thus, the response pattern elicited by H-7 is different from that of other leukocyte activators such as chemotactic peptides, PMA or diacylglycerols. The finding that H-7 can elicit shape changes, actin polymerization and pinocytosis suggests that these events can occur without activation of protein kinase C (PKC). PMA-induced shape changes and stimulation of pinocytosis were not inhibited by H-7.
Collapse
Affiliation(s)
- H U Keller
- Institute of Pathology, University of Bern, Switzerland
| | | | | | | |
Collapse
|
49
|
Thomas N, Keller HU. Photometric calibration of the Halley Multicolour Camera. Appl Opt 1990; 29:1503-1519. [PMID: 20563034 DOI: 10.1364/ao.29.001503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The absolute (photometric) calibration of the Halley Multicolour Camera (HMC) is described. HMC, prior to its observations of comet Halley on 13-14 Mar. 1986, imaged several stars and planets. The fluxes from the objects and the observed signals in digital units (DU) have been computed. A spectrally independent measure of the response of the instrument has been determined. This value has been used to derive conversion factors from DU to mW m(-2) sr(-1) and reflectivities for all HMC configurations.
Collapse
|
50
|
Sarkar MR, Rahn BA, Pfister U, Keller HU, Perren SM. Induction of monocyte chemotaxis in devascularized rabbit bone. Arch Orthop Trauma Surg 1990; 109:97-101. [PMID: 2317134 DOI: 10.1007/bf00439387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Temporary impairment of blood supply has been suggested to cause bone remodeling. The degradation of cells and matrix and the attraction of resorbing cells were examined in this study. Bone specimens of rabbits were stored in vitro for 2-20 days. At the end of this aging process the probes were tested for their chemotactic activity toward autologous leukocytes in a diffusion chamber. Both supernatant from the aged bone specimens and ground bone particles exhibited significant chemotactic activity that was specifically attracting monocytes. It is suggested that soluble bone matrix proteins or degeneration products liberated during ischemic damage to cortical bone initiate the resorptive process.
Collapse
Affiliation(s)
- M R Sarkar
- Abteilung für Unfallchirurgie, Städtisches Klinikum, Karlsruhe, Federal Republic of Germany
| | | | | | | | | |
Collapse
|