1
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Hunter A, Beck S, Cappelli E, Margot F, Straub M, Alexanian Y, Gatti G, Watson MD, Kim TK, Cacho C, Plumb NC, Shi M, Radović M, Sokolov DA, Mackenzie AP, Zingl M, Mravlje J, Georges A, Baumberger F, Tamai A. Fate of Quasiparticles at High Temperature in the Correlated Metal Sr_{2}RuO_{4}. Phys Rev Lett 2023; 131:236502. [PMID: 38134803 DOI: 10.1103/physrevlett.131.236502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 11/08/2023] [Indexed: 12/24/2023]
Abstract
We study the temperature evolution of quasiparticles in the correlated metal Sr_{2}RuO_{4}. Our angle resolved photoemission data show that quasiparticles persist up to temperatures above 200 K, far beyond the Fermi liquid regime. Extracting the quasiparticle self-energy, we demonstrate that the quasiparticle residue Z increases with increasing temperature. Quasiparticles eventually disappear on approaching the bad metal state of Sr_{2}RuO_{4} not by losing weight but via excessive broadening from super-Planckian scattering. We further show that the Fermi surface of Sr_{2}RuO_{4}-defined as the loci where the spectral function peaks-deflates with increasing temperature. These findings are in semiquantitative agreement with dynamical mean field theory calculations.
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Affiliation(s)
- A Hunter
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - S Beck
- Center for Computational Quantum Physics, Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
| | - E Cappelli
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - F Margot
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - M Straub
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Y Alexanian
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - G Gatti
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - M D Watson
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - C Cacho
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Radović
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - D A Sokolov
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
| | - A P Mackenzie
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St. Andrews, St. Andrews KY16 9SS, United Kingdom
| | - M Zingl
- Center for Computational Quantum Physics, Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
| | - J Mravlje
- Department of Theoretical Physics, Institute Jozef Stefan, Jamova 39, SI-1001 Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana
| | - A Georges
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
- Center for Computational Quantum Physics, Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
- Collège de France, 11 Place Marcelin Berthelot, 75005 Paris, France
- Centre de Physique Théorique, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris, 91128 Palaiseau Cedex, France
| | - F Baumberger
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - A Tamai
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
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2
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Gatti G, Issing J, Rademaker L, Margot F, de Jong TA, van der Molen SJ, Teyssier J, Kim TK, Watson MD, Cacho C, Dudin P, Avila J, Edwards KC, Paruch P, Ubrig N, Gutiérrez-Lezama I, Morpurgo AF, Tamai A, Baumberger F. Flat Γ Moiré Bands in Twisted Bilayer WSe_{2}. Phys Rev Lett 2023; 131:046401. [PMID: 37566843 DOI: 10.1103/physrevlett.131.046401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 06/26/2023] [Indexed: 08/13/2023]
Abstract
The recent observation of correlated phases in transition metal dichalcogenide moiré systems at integer and fractional filling promises new insight into metal-insulator transitions and the unusual states of matter that can emerge near such transitions. Here, we combine real- and momentum-space mapping techniques to study moiré superlattice effects in 57.4° twisted WSe_{2} (tWSe_{2}). Our data reveal a split-off flat band that derives from the monolayer Γ states. Using advanced data analysis, we directly quantify the moiré potential from our data. We further demonstrate that the global valence band maximum in tWSe_{2} is close in energy to this flat band but derives from the monolayer K states which show weaker superlattice effects. These results constrain theoretical models and open the perspective that Γ-valley flat bands might be involved in the correlated physics of twisted WSe_{2}.
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Affiliation(s)
- G Gatti
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - J Issing
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - L Rademaker
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
- Department of Theoretical Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - F Margot
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - T A de Jong
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - S J van der Molen
- Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Leiden, The Netherlands
| | - J Teyssier
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - M D Watson
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - C Cacho
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - P Dudin
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin-BP 48, 91192 Gif sur Yvette Cedex, France
| | - J Avila
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint Aubin-BP 48, 91192 Gif sur Yvette Cedex, France
| | - K Cordero Edwards
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - P Paruch
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - N Ubrig
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
| | - I Gutiérrez-Lezama
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
| | - A F Morpurgo
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
- Department of Applied Physics, University of Geneva, 24 Quai Ernest Ansermet, CH-1211 Geneva, Switzerland
| | - A Tamai
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - F Baumberger
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva, Switzerland
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
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3
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Marques CA, Bahramy MS, Trainer C, Marković I, Watson MD, Mazzola F, Rajan A, Raub TD, King PDC, Wahl P. Tomographic mapping of the hidden dimension in quasi-particle interference. Nat Commun 2021; 12:6739. [PMID: 34795276 PMCID: PMC8602440 DOI: 10.1038/s41467-021-27082-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 11/04/2021] [Indexed: 11/12/2022] Open
Abstract
Quasiparticle interference (QPI) imaging is well established to study the low-energy electronic structure in strongly correlated electron materials with unrivalled energy resolution. Yet, being a surface-sensitive technique, the interpretation of QPI only works well for anisotropic materials, where the dispersion in the direction perpendicular to the surface can be neglected and the quasiparticle interference is dominated by a quasi-2D electronic structure. Here, we explore QPI imaging of galena, a material with an electronic structure that does not exhibit pronounced anisotropy. We find that the quasiparticle interference signal is dominated by scattering vectors which are parallel to the surface plane however originate from bias-dependent cuts of the 3D electronic structure. We develop a formalism for the theoretical description of the QPI signal and demonstrate how this quasiparticle tomography can be used to obtain information about the 3D electronic structure and orbital character of the bands.
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Affiliation(s)
- C A Marques
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - M S Bahramy
- Department of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
| | - C Trainer
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - I Marković
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - M D Watson
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - F Mazzola
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - A Rajan
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - T D Raub
- School of Earth and Environmental Sciences, University of St Andrews, Irvine Building, St Andrews, KY16 9AL, UK
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK
| | - P Wahl
- SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK.
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4
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Noguchi R, Takahashi T, Kuroda K, Ochi M, Shirasawa T, Sakano M, Bareille C, Nakayama M, Watson MD, Yaji K, Harasawa A, Iwasawa H, Dudin P, Kim TK, Hoesch M, Kandyba V, Giampietri A, Barinov A, Shin S, Arita R, Sasagawa T, Kondo T. Publisher Correction: A weak topological insulator state in quasi-one-dimensional bismuth iodide. Nature 2020; 584:E4. [PMID: 32690939 DOI: 10.1038/s41586-020-2392-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Affiliation(s)
- Ryo Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - T Takahashi
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Japan
| | - K Kuroda
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - M Ochi
- Department of Physics, Osaka University, Toyonaka, Japan
| | - T Shirasawa
- National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - M Sakano
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan.,Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), The University of Tokyo, Tokyo, Japan
| | - C Bareille
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - M Nakayama
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - M D Watson
- Diamond Light Source, Harwell Campus, Didcot, UK
| | - K Yaji
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - A Harasawa
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - H Iwasawa
- Diamond Light Source, Harwell Campus, Didcot, UK.,Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - P Dudin
- Diamond Light Source, Harwell Campus, Didcot, UK
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot, UK.,DESY Photon Science, Deutsches Elektronen-Synchrotron, Hamburg, Germany
| | - V Kandyba
- Elettra - Sincrotrone Trieste, Basovizza, Italy
| | | | - A Barinov
- Elettra - Sincrotrone Trieste, Basovizza, Italy
| | - S Shin
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan
| | - R Arita
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
| | - T Sasagawa
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Japan.
| | - Takeshi Kondo
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan.
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5
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Sunko V, Mazzola F, Kitamura S, Khim S, Kushwaha P, Clark OJ, Watson MD, Marković I, Biswas D, Pourovskii L, Kim TK, Lee TL, Thakur PK, Rosner H, Georges A, Moessner R, Oka T, Mackenzie AP, King PDC. Probing spin correlations using angle-resolved photoemission in a coupled metallic/Mott insulator system. Sci Adv 2020; 6:eaaz0611. [PMID: 32128385 PMCID: PMC7032925 DOI: 10.1126/sciadv.aaz0611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 10/29/2019] [Indexed: 06/10/2023]
Abstract
A nearly free electron metal and a Mott insulating state can be thought of as opposite ends of the spectrum of possibilities for the motion of electrons in a solid. Understanding their interaction lies at the heart of the correlated electron problem. In the magnetic oxide metal PdCrO2, nearly free and Mott-localized electrons exist in alternating layers, forming natural heterostructures. Using angle-resolved photoemission spectroscopy, quantitatively supported by a strong coupling analysis, we show that the coupling between these layers leads to an "intertwined" excitation that is a convolution of the charge spectrum of the metallic layer and the spin susceptibility of the Mott layer. Our findings establish PdCrO2 as a model system in which to probe Kondo lattice physics and also open new routes to use the a priori nonmagnetic probe of photoemission to gain insights into the spin susceptibility of correlated electron materials.
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Affiliation(s)
- V. Sunko
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - F. Mazzola
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - S. Kitamura
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany
| | - S. Khim
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - P. Kushwaha
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - O. J. Clark
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - M. D. Watson
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - I. Marković
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - D. Biswas
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - L. Pourovskii
- CPHT, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, F-91128 Palaiseau, France
- Institut de Physique, Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
| | - T. K. Kim
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - T.-L. Lee
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - P. K. Thakur
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - H. Rosner
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - A. Georges
- CPHT, CNRS, Ecole Polytechnique, Institut Polytechnique de Paris, F-91128 Palaiseau, France
- Institut de Physique, Collège de France, 11 place Marcelin Berthelot, 75005 Paris, France
- Center for Computational Quantum Physics, Flatiron Institute, New York, NY 10010, USA
- DQMP, Université de Genève, 24 quai Ernest Ansermet, CH-1211 Genève, Switzerland
| | - R. Moessner
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany
| | - T. Oka
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany
| | - A. P. Mackenzie
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - P. D. C. King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
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6
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Marković I, Hooley CA, Clark OJ, Mazzola F, Watson MD, Riley JM, Volckaert K, Underwood K, Dyer MS, Murgatroyd PAE, Murphy KJ, Fèvre PL, Bertran F, Fujii J, Vobornik I, Wu S, Okuda T, Alaria J, King PDC. Weyl-like points from band inversions of spin-polarised surface states in NbGeSb. Nat Commun 2019; 10:5485. [PMID: 31792208 PMCID: PMC6888910 DOI: 10.1038/s41467-019-13464-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/08/2019] [Indexed: 11/09/2022] Open
Abstract
Band inversions are key to stabilising a variety of novel electronic states in solids, from topological surface states to the formation of symmetry-protected three-dimensional Dirac and Weyl points and nodal-line semimetals. Here, we create a band inversion not of bulk states, but rather between manifolds of surface states. We realise this by aliovalent substitution of Nb for Zr and Sb for S in the ZrSiS family of nonsymmorphic semimetals. Using angle-resolved photoemission and density-functional theory, we show how two pairs of surface states, known from ZrSiS, are driven to intersect each other near the Fermi level in NbGeSb, and to develop pronounced spin splittings. We demonstrate how mirror symmetry leads to protected crossing points in the resulting spin-orbital entangled surface band structure, thereby stabilising surface state analogues of three-dimensional Weyl points. More generally, our observations suggest new opportunities for engineering topologically and symmetry-protected states via band inversions of surface states.
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Affiliation(s)
- I Marković
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom.,Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187, Dresden, Germany
| | - C A Hooley
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
| | - O J Clark
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
| | - F Mazzola
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
| | - M D Watson
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
| | - J M Riley
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
| | - K Volckaert
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
| | - K Underwood
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom
| | - M S Dyer
- Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD, United Kingdom
| | - P A E Murgatroyd
- Department of Physics, University of Liverpool, Liverpool, L69 7ZE, United Kingdom
| | - K J Murphy
- Department of Physics, University of Liverpool, Liverpool, L69 7ZE, United Kingdom
| | - P Le Fèvre
- Synchrotron SOLEIL, CNRS-CEA, L'Orme des Merisiers, Saint-Aubin-BP48, 91192, Gif-sur-Yvette, France
| | - F Bertran
- Synchrotron SOLEIL, CNRS-CEA, L'Orme des Merisiers, Saint-Aubin-BP48, 91192, Gif-sur-Yvette, France
| | - J Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S.14, Km 163.5, 34149, Trieste, Italy
| | - I Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, S.S.14, Km 163.5, 34149, Trieste, Italy
| | - S Wu
- Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, 739-8526, Japan
| | - T Okuda
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, 739-0046, Japan
| | - J Alaria
- Department of Physics, University of Liverpool, Liverpool, L69 7ZE, United Kingdom
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, United Kingdom.
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7
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Noguchi R, Takahashi T, Kuroda K, Ochi M, Shirasawa T, Sakano M, Bareille C, Nakayama M, Watson MD, Yaji K, Harasawa A, Iwasawa H, Dudin P, Kim TK, Hoesch M, Kandyba V, Giampietri A, Barinov A, Shin S, Arita R, Sasagawa T, Kondo T. A weak topological insulator state in quasi-one-dimensional bismuth iodide. Nature 2019; 566:518-522. [DOI: 10.1038/s41586-019-0927-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 11/24/2018] [Indexed: 11/09/2022]
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8
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Riley JM, Caruso F, Verdi C, Duffy LB, Watson MD, Bawden L, Volckaert K, van der Laan G, Hesjedal T, Hoesch M, Giustino F, King PDC. Crossover from lattice to plasmonic polarons of a spin-polarised electron gas in ferromagnetic EuO. Nat Commun 2018; 9:2305. [PMID: 29899336 PMCID: PMC5998015 DOI: 10.1038/s41467-018-04749-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 05/22/2018] [Indexed: 11/10/2022] Open
Abstract
Strong many-body interactions in solids yield a host of fascinating and potentially useful physical properties. Here, from angle-resolved photoemission experiments and ab initio many-body calculations, we demonstrate how a strong coupling of conduction electrons with collective plasmon excitations of their own Fermi sea leads to the formation of plasmonic polarons in the doped ferromagnetic semiconductor EuO. We observe how these exhibit a significant tunability with charge carrier doping, leading to a polaronic liquid that is qualitatively distinct from its more conventional lattice-dominated analogue. Our study thus suggests powerful opportunities for tailoring quantum many-body interactions in solids via dilute charge carrier doping.
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Affiliation(s)
- J M Riley
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - F Caruso
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, 12489, Germany
| | - C Verdi
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - L B Duffy
- Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
- ISIS, STFC, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK
| | - M D Watson
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - L Bawden
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
| | - K Volckaert
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK
| | - G van der Laan
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK
| | - T Hesjedal
- Department of Physics, University of Oxford, Oxford, OX1 3PU, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, UK.
- DESY Photon Science, Deutsches Elektronen-Synchrotron, Hamburg, D-22603, Germany.
| | - F Giustino
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
- Department of Materials Science and Engineering, Cornell University, Ithaca, New York, 14853, USA.
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, KY16 9SS, UK.
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9
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Watson MD, Feng Y, Nicholson CW, Monney C, Riley JM, Iwasawa H, Refson K, Sacksteder V, Adroja DT, Zhao J, Hoesch M. Multiband One-Dimensional Electronic Structure and Spectroscopic Signature of Tomonaga-Luttinger Liquid Behavior in K_{2}Cr_{3}As_{3}. Phys Rev Lett 2017; 118:097002. [PMID: 28306267 DOI: 10.1103/physrevlett.118.097002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Indexed: 06/06/2023]
Abstract
We present angle-resolved photoemission spectroscopy measurements of the quasi-one-dimensional superconductor K_{2}Cr_{3}As_{3}. We find that the Fermi surface contains two Fermi surface sheets, with linearly dispersing bands not displaying any significant band renormalizations. The one-dimensional band dispersions display a suppression of spectral intensity approaching the Fermi level according to a linear power law, over an energy range of ∼200 meV. This is interpreted as a signature of Tomonoga-Luttinger liquid physics, which provides a new perspective on the possibly unconventional superconductivity in this family of compounds.
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Affiliation(s)
- M D Watson
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - Y Feng
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - C W Nicholson
- Department of Physical Chemistry, Fritz-Haber-Institut of the Max Planck Society, Faradayweg 4-6, Berlin 14915, Germany
| | - C Monney
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - J M Riley
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, United Kingdom
| | - H Iwasawa
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
| | - K Refson
- Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom
| | - V Sacksteder
- Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom
| | - D T Adroja
- ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX, United Kingdom
- Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa
| | - J Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot, OX11 0DE, United Kingdom
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10
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Watson MD, Yamashita T, Kasahara S, Knafo W, Nardone M, Béard J, Hardy F, McCollam A, Narayanan A, Blake SF, Wolf T, Haghighirad AA, Meingast C, Schofield AJ, V Löhneysen H, Matsuda Y, Coldea AI, Shibauchi T. Publisher's Note: Dichotomy between the Hole and Electron Behavior in Multiband Superconductor FeSe Probed by Ultrahigh Magnetic Fields [Phys. Rev. Lett. 115, 027006 (2015)]. Phys Rev Lett 2015; 115:219902. [PMID: 26636880 DOI: 10.1103/physrevlett.115.219902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Indexed: 06/05/2023]
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11
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Narayanan A, Watson MD, Blake SF, Bruyant N, Drigo L, Chen YL, Prabhakaran D, Yan B, Felser C, Kong T, Canfield PC, Coldea AI. Linear magnetoresistance caused by mobility fluctuations in n-doped Cd(3)As(2). Phys Rev Lett 2015; 114:117201. [PMID: 25839304 DOI: 10.1103/physrevlett.114.117201] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Indexed: 06/04/2023]
Abstract
Cd(3)As(2) is a candidate three-dimensional Dirac semimetal which has exceedingly high mobility and nonsaturating linear magnetoresistance that may be relevant for future practical applications. We report magnetotransport and tunnel diode oscillation measurements on Cd(3)As(2), in magnetic fields up to 65 T and temperatures between 1.5 and 300 K. We find that the nonsaturating linear magnetoresistance persists up to 65 T and it is likely caused by disorder effects, as it scales with the high mobility rather than directly linked to Fermi surface changes even when approaching the quantum limit. From the observed quantum oscillations, we determine the bulk three-dimensional Fermi surface having signatures of Dirac behavior with a nontrivial Berry phase shift, very light effective quasiparticle masses, and clear deviations from the band-structure predictions. In very high fields we also detect signatures of large Zeeman spin splitting (g∼16).
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Affiliation(s)
- A Narayanan
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - M D Watson
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - S F Blake
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - N Bruyant
- Laboratoire National des Champs Magnetiques Intenses (CNRS), 31077 Toulouse, France
| | - L Drigo
- Laboratoire National des Champs Magnetiques Intenses (CNRS), 31077 Toulouse, France
| | - Y L Chen
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - D Prabhakaran
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - B Yan
- Max-Planck-Institut fur Chemische Physik fester Stoffe, 01187 Dresden, Germany
| | - C Felser
- Laboratoire National des Champs Magnetiques Intenses (CNRS), 31077 Toulouse, France
| | - T Kong
- Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - P C Canfield
- Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - A I Coldea
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
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12
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Walmsley P, Putzke C, Malone L, Guillamón I, Vignolles D, Proust C, Badoux S, Coldea AI, Watson MD, Kasahara S, Mizukami Y, Shibauchi T, Matsuda Y, Carrington A. Quasiparticle mass enhancement close to the quantum critical point in BaFe2(As(1-x)P(x))2. Phys Rev Lett 2013; 110:257002. [PMID: 23829753 DOI: 10.1103/physrevlett.110.257002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 05/10/2013] [Indexed: 06/02/2023]
Abstract
We report a combined study of the specific heat and de Haas-van Alphen effect in the iron-pnictide superconductor BaFe2(As(1-x)P(x))2. Our data when combined with results for the magnetic penetration depth give compelling evidence for the existence of a quantum critical point close to x=0.30 which affects the majority of the Fermi surface by enhancing the quasiparticle mass. The results show that the sharp peak in the inverse superfluid density seen in this system results from a strong increase in the quasiparticle mass at the quantum critical point.
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Affiliation(s)
- P Walmsley
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
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13
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Putzke C, Coldea AI, Guillamón I, Vignolles D, McCollam A, Leboeuf D, Watson MD, Mazin II, Kasahara S, Terashima T, Shibauchi T, Matsuda Y, Carrington A. de Haas-van Alphen study of the Fermi surfaces of superconducting LiFeP and LiFeAs. Phys Rev Lett 2012; 108:047002. [PMID: 22400881 DOI: 10.1103/physrevlett.108.047002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Indexed: 05/31/2023]
Abstract
We report a de Haas-van Alphen oscillation study of the 111 iron pnictide superconductors LiFeAs with T(c) ≈ 18 K and LiFeP with T(c) ≈ 5 K. We find that for both compounds the Fermi surface topology is in good agreement with density functional band-structure calculations and has almost nested electron and hole bands. The effective masses generally show significant enhancement, up to ~3 for LiFeP and ~5 for LiFeAs. However, one hole Fermi surface in LiFeP shows a very small enhancement, as compared with its other sheets. This difference probably results from k-dependent coupling to spin fluctuations and may be the origin of the different nodal and nodeless superconducting gap structures in LiFeP and LiFeAs, respectively.
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Affiliation(s)
- C Putzke
- HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom
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14
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Jäckel F, Watson MD, Müllen K, Rabe JP. Prototypical single-molecule chemical-field-effect transistor with nanometer-sized gates. Phys Rev Lett 2004; 92:188303. [PMID: 15169538 DOI: 10.1103/physrevlett.92.188303] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2003] [Indexed: 05/24/2023]
Abstract
A prototypical single-molecule chemical-field-effect transistor is presented, in which the current through a hybrid-molecular diode is modified by nanometer-sized charge transfer complexes covalently linked to a molecule in an STM junction. The effect is attributed to an interface dipole which shifts the substrate work function by approximately 120 meV. It is induced by the complexes from electron acceptors covalently bound to the molecule in the gap and electron donors coming from the ambient fluid. This proof of principle is regarded as a major step towards monomolecular electronic devices.
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Affiliation(s)
- F Jäckel
- Department of Physics, Humboldt University Berlin, Newtonstrasse 15, 12489 Berlin, Germany
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15
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de la Torre JC, Pappas BA, Prevot V, Emmerling MR, Mantione K, Fortin T, Watson MD, Stefano GB. Hippocampal nitric oxide upregulation precedes memory loss and A beta 1-40 accumulation after chronic brain hypoperfusion in rats. Neurol Res 2003; 25:635-41. [PMID: 14503018 DOI: 10.1179/016164103101201931] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [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: 10/31/2022]
Abstract
Chronic brain hypoperfusion (CBH) using permanent occlusion of both common carotid arteries in an aging rat model, has been shown to mimic human mild cognitive impairment (MCI), an acknowledged high risk condition that often converts to Alzheimer's disease. An aging rat model was used to determine whether hippocampal nitric oxide (NO) is abnormally expressed following CBH for two or eight weeks. At each time point, spatial memory was measured with the Morris water maze and hippocampal A beta 1-40/1-42 concentrations were obtained using sandwich ELISA. Real-time amperometric measures of NO representing the constitutive isoforms of neuronal nitric oxide synthase (nNOS) and endothelial (e)NOS were also taken at each time point to ascertain whether NO levels changed as a result of CBH, and if so, whether such NO changes preceded or followed any memory or amyloid-beta pathology. We found that two weeks after CBH, NO hippocampal levels were upregulated nearly four-fold when compared to nonoccluded rats but no alteration in spatial memory of A beta products were observed at this time point. By contrast, NO concentration had declined to control levels by eight weeks but spatial memory was found significantly impaired and A beta 1-40 (but not A beta 1-42) had increased in the CBH group when compared to control rats. Since changes in shear stress are known to upregulate eNOS but generally not nNOS, these results suggest that shear stress induced by CBH hyperactivated vascular NO derived from eNOS in the first two weeks as a reaction by the capillary endothelium to maintain homeostasis of local cerebral blood flow. The return of vascular NO to basal levels after eight weeks of CBH may have triggered metabolic changes within hippocampal cells resulting in hippocampal dysfunction as reflected by spatial memory impairment and by accumulation of A beta 1-40 peptide. In conclusion, our study shows that CBH initiates spatial memory loss in aging rats thus mimicking human MCI and also increases A beta 1-40 in the hippocampus. The memory and amyloid changes are preceded by NO upregulation in the hippocampus. These preliminary findings may be important in understanding, at least in part, the molecular mechanisms that precede memory impairment during chronic brain ischemia and as such, the pre-clinical stage leading to Alzheimer's disease.
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Affiliation(s)
- J C de la Torre
- Department of Pathology, University of California, San Diego, CA.
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17
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Fleming AJ, Coleman JN, Dalton AB, Fechtenkötter A, Watson MD, Müllen K, Byrne HJ, Blau WJ. Optical Spectroscopy of Isolated and Aggregate Hexabenzocoronene Derivatives: A Study of Self-Assembling Molecular Nanowires. J Phys Chem B 2002. [DOI: 10.1021/jp0262618] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. J. Fleming
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
| | - J. N. Coleman
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
| | - A. B. Dalton
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
| | - A. Fechtenkötter
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
| | - M. D. Watson
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
| | - K. Müllen
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
| | - H. J. Byrne
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
| | - W. J. Blau
- Department of Physics, Trinity College Dublin, Dublin 2, Ireland, UTD Nanotech Institute, Richardson, Texas 75083-0688, Max-Plank-Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany, and FOCAS, School of Physics, Dublin Institute of Technology, Dublin 8, Ireland
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18
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Watson MD, Fechtenkötter A, Müllen K. Big is beautiful--"aromaticity" revisited from the viewpoint of macromolecular and supramolecular benzene chemistry. Chem Rev 2001; 101:1267-300. [PMID: 11710221 DOI: 10.1021/cr990322p] [Citation(s) in RCA: 1037] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M D Watson
- Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz, Germany
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19
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Abstract
Six open reading frames (ORFs) of unknown function from the right arm of Saccharomyces cerevisiae chromosome XII were deleted in two genetic backgrounds by disruption cassettes with regions of short flanking homology. This work was carried out within the framework of the EUROFAN consortium. The SFH disruption cassettes, obtained by PCR, were made by amplification of the kanMX marker module with oligonucleotides containing approximately 40 bp of homology to either the promoter or translation terminator regions of the relevant ORF. Transformants resistant to geneticin (G418) were selected. The SFH disruption cassettes were cloned into a bacterial vector. Each cognate gene was also cloned into a yeast centromeric plasmid. Sporulation and tetrad analysis of the disrupted heterozygous strains revealed that ORF YLR153c (now known as ACS2) is essential. Basic phenotypic analysis was performed on haploid deletants of both mating types of the five non-essential ORFs, YLR082c (now known as SRL2), YLR149c, YLR151c, YLR152c and YLR154c. Plate growth tests on different media at 15 degrees C, 30 degrees C and 37 degrees C did not reveal any significant differences between parental and mutant cells. Mating and sporulation efficiencies were not affected in any of the viable disruptants as compared to wild-type cells.
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Affiliation(s)
- M D Watson
- Department of Biological Sciences, University of Durham, South Road, Durham DH1 3LE, UK.
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Watson MD. Current awareness on yeast. Yeast 2001; 18:481-8. [PMID: 11255257] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
In order to keep subscribers up-to-date with the latest developments in their field, this current awareness service is provided by John Wiley & Sons and contains newly-published material on yeasts. Each bibliography is divided into 10 sections. 1 Books, Reviews & Symposia; 2 General; 3 Biochemistry; 4 Biotechnology; 5 Cell Biology; 6 Gene Expression; 7 Genetics; 8 Physiology; 9 Medical Mycology; 10 Recombinant DNA Technology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted. (4 weeks journals - search completed 3rd Jan. 2001)
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Affiliation(s)
- M D Watson
- Department of Biological Sciences, University of Durham, South Road, Durham DH1 3LE, UK
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21
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Abstract
Complement proteins are integral components of amyloid plaques and cerebral vascular amyloid in Alzheimer brains. They can be found at the earliest stages of amyloid deposition and their activation coincides with the clinical expression of Alzheimer's dementia. This review will examine the origins of complement in the brain and the role of beta-amyloid peptide (Abeta) in complement activation in Alzheimer's disease, an event that might serve as a nidus of chronic inflammation. Pharmacology therapies that may serve to inhibit Abeta-mediated complement activation will also be discussed.
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Affiliation(s)
- M R Emmerling
- Neuroscience Therapeutics, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, MI 48106, USA.
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Emmerling MR, Morganti-Kossmann MC, Kossmann T, Stahel PF, Watson MD, Evans LM, Mehta PD, Spiegel K, Kuo YM, Roher AE, Raby CA. Traumatic brain injury elevates the Alzheimer's amyloid peptide A beta 42 in human CSF. A possible role for nerve cell injury. Ann N Y Acad Sci 2000; 903:118-22. [PMID: 10818496 DOI: 10.1111/j.1749-6632.2000.tb06357.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [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: 11/29/2022]
Abstract
The increased risk for Alzheimer's Disease (AD) associated with traumatic brain injury (TBI) suggests that environmental insults may influence the development of this age-related dementia. Recently, we have shown that the levels of the beta-amyloid peptide (A beta 1-42) increase in the cerebrospinal fluid (CSF) of patients after severe brain injury and remain elevated for some time after the initial event. The relationships of elevated A beta with markers of blood-brain barrier (BBB) disruption, inflammation, and nerve cell or axonal injury were evaluated in CSF samples taken daily from TBI patients. This analysis reveals that the rise in A beta 1-42 is best correlated with possible markers of neuronal or axonal injury, the cytoskeletal protein tau, neuron-specific enolase (NSE), and apolipoprotein E (ApoE). Similar or better correlations were observed between A beta 1-40 and the three aforementioned markers. These results imply that the degree of brain injury may play a decisive role in determining the levels of A beta 1-42 and A beta 1-40 in the CSF of TBI patients. Inflammation and alterations in BBB may play lesser, but nonetheless significant, roles in determining the A beta level in CSF after brain injury.
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Affiliation(s)
- M R Emmerling
- Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, Michigan 48105, USA.
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Abstract
Early-thymectomized (Tx) Xenopus frogs, which are permanently deficient in T cells, are used as a model sytem for the characterization of novel monoclonal antibodies (mAb) which identify candidate NK cells at the amphibian level of evolution. Hybridomas, generated from mice immunized with splenocytes from Tx Xenopus following B cell and thrombocyte depletion, were screened by flow cytometry. Three mAb (1F8, 4D4 and 1G5) were identified that stained increased proportions of splenocytes from Tx compared with control frogs. These mAb identified lymphoid populations from Xenopus spleen, liver and gut which, after 48 h culture in growth factor-rich medium, exhibited spontanous killing of MHC-deficient allotumor targets. mAb-defined splenocytes also rapidly induced apoptosis of such tumor targets. Dual color analysis confirmed that NK cells are neither T nor B cells. Cytospins of splenocytes isolated with anti-NK mAb revealed large lymphoid cells with distinct pseudopodia. Immunohistology indicated each anti-NK mAb routinely labeled cells within the gut epithelium but NK cells were difficult to visualize in spleen sections. Western blotting of spleen, liver and intestinal lysates subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that 1G5 reacted strongly with protein bands of approximately 70 - 85 kDa, whereas mAb 1F8 and 4D4 stained less intensely, but identified similar protein bands.
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Affiliation(s)
- T L Horton
- Department of Biological Sciences, University of Durham, Durham, GB
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Kane MD, Schwarz RD, St Pierre L, Watson MD, Emmerling MR, Boxer PA, Walker GK. Inhibitors of V-type ATPases, bafilomycin A1 and concanamycin A, protect against beta-amyloid-mediated effects on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction. J Neurochem 1999; 72:1939-47. [PMID: 10217271 DOI: 10.1046/j.1471-4159.1999.0721939.x] [Citation(s) in RCA: 18] [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]
Abstract
The functional viability of cells can be evaluated using a number of different assay determinants. One common assay involves exposing cells to 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which is converted intracellularly to a colored formazan precipitate and often used to assess amyloid peptide-induced cytotoxic effects. The MTT assay was employed to evaluate the role of endosomal uptake and lysosomal acidification in amyloid peptide-treated differentiated PC12 cell cultures using selective vacuolar-type (V-type) ATPase inhibitors. The macrolides bafilomycin A1 (BAF) and concanamycin A (CON) block lysosomal acidification through selective inhibition of the V-type ATPase. Treating nerve growth factor-differentiated PC12 cells with nanomolar concentrations of BAF or CON provides complete protection against the effects of beta-amyloid peptides Abeta(1-42), Abeta(1-40), and Abeta(25-35) and of amylin on MTT dye conversion. These macrolides do not inhibit peptide aggregation, act as antioxidants, or inhibit Abeta uptake by cells. Measurements of lysosomal acidification reveal that the concentrations of BAF and CON effective in reversing Abeta-mediated MTT dye conversion also reverse lysosomal pH. These results suggest that lysosomal acidification is necessary for Abeta effects on MTT dye conversion.
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Affiliation(s)
- M D Kane
- Neuroscience Therapeutics, Parke-Davis Pharmaceutical Research, Warner-Lambert Company, Ann Arbor, Michigan 48105, USA
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Plummer JS, Cai C, Hays SJ, Gilmore JL, Emmerling MR, Michael W, Narasimhan LS, Watson MD, Wang K, Nath R, Evans LM, Jaen JC. Benzenesulfonamide derivatives of 2-substituted 4H-3,1-benzoxazin-4-ones and benzthiazin-4-ones as inhibitors of complement C1r protease. Bioorg Med Chem Lett 1999; 9:815-20. [PMID: 10206542 DOI: 10.1016/s0960-894x(99)00095-5] [Citation(s) in RCA: 16] [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
A series of 2-sulfonyl-4H-3,1-benzoxazinones was prepared that inhibit C1r protease in vitro. Several compounds were found to be selective for C1r verses the related serine protease trypsin. Selected compounds demonstrated functional activity in a hemolysis assay.
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Affiliation(s)
- J S Plummer
- Department of Chemistry, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, MI 48105, USA
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27
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Horton JD, Horton TL, Dzialo R, Gravenor I, Minter R, Ritchie P, Gartland L, Watson MD, Cooper MD. T-cell and natural killer cell development in thymectomized Xenopus. Immunol Rev 1998; 166:245-58. [PMID: 9914917 DOI: 10.1111/j.1600-065x.1998.tb01267.x] [Citation(s) in RCA: 28] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The Xenopus early-thymectomy model system is used to investigate the extent to which the thymus controls T-cell development and to probe the evolution of natural killer (NK) cells. Loss of T-cell function following thymectomy, together with the paucity of cells expressing monoclonal antibody-defined T-cell surface markers, and greatly reduced expression of T-cell receptor beta transcripts in spleen, liver and intestine, indicate that T-cell development in minimal in the absence of the thymus. Our findings therefore mitigate against the idea that a substantial extrathymic pathway of T-cell development exists in early vertebrate evolution. Rather, they suggest that in this amphibian representative T cells are predominately thymus dependent. In vitro studies with control and thymectomized Xenopus splenocytes reveal that a non-T/non-B population and also two T-cell subsets all display natural cytotoxicity towards allogeneic thymus lymphoid tumour cells (which are deficient in MHC antigen expression). Since Xenopus thymectomized early in larval development are permanently deficient in T cells, they may provide a useful phylogenetic model for the study of NK cells.
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Affiliation(s)
- J D Horton
- Department of Biological Sciences, University of Durham, UK.
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Raby CA, Morganti-Kossmann MC, Kossmann T, Stahel PF, Watson MD, Evans LM, Mehta PD, Spiegel K, Kuo YM, Roher AE, Emmerling MR. Traumatic brain injury increases beta-amyloid peptide 1-42 in cerebrospinal fluid. J Neurochem 1998; 71:2505-9. [PMID: 9832149 DOI: 10.1046/j.1471-4159.1998.71062505.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.0] [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: 11/20/2022]
Abstract
The beta-amyloid peptides, A beta1-42 and A beta1-40, were quantified in ventricular CSF taken daily for up to 3 weeks from six individuals with severe traumatic brain injury (TBI). There was considerable interindividual variability in the levels of A beta peptides, but in general A beta1-42 levels equalled or exceeded those of A beta1-40. Averaging the daily totals of our trauma cohort revealed that the levels of A beta1-42 and A beta1-40 rose after injury, peaking in the first week and then declining toward control levels over the next 2 weeks. A beta1-42 levels were on average two to three times higher in the trauma cohort than in CSF from nontrauma samples. Compared with nontrauma samples, the A beta1-40/A beta1-42 ratio decreased about fivefold in the trauma patients, further indicative of increased A beta1-42 levels. The ratio remained low at all time points studied. No change was measured in the levels of beta-amyloid precursor protein during the same interval. These results suggest that A beta1-42 becomes elevated in the CSF after severe brain trauma.
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Affiliation(s)
- C A Raby
- Neuroscience Therapeutics, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, Michigan 48105, USA
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Horton TL, Ritchie P, Watson MD, Horton JD. Natural cytotoxicity towards allogeneic tumour targets in Xenopus mediated by diverse splenocyte populations. Dev Comp Immunol 1998; 22:217-230. [PMID: 9639091 DOI: 10.1016/s0145-305x(98)00003-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We have recently demonstrated NK-like activity in the spleen of the clawed frog, Xenopus laevis. This paper investigates the cellular basis of this natural cytotoxicity. Significant levels of cytotoxicity towards B3B7 allogeneic thymus tumour targets, that express neither class Ia nor class II MHC proteins, occurred after splenocytes from either control or early-thymectomized (Tx) year-old Xenopus were cultured for 48 hours. Killing by Tx cells required their culture in growth factor-rich medium (GFM) obtained from concanavalin A-stimulated cells. Immunomagnetic cell sorting revealed that cytotoxic effectors in both control and Tx frogs were found in the B cell-depleted population, but never in the B cell-enriched fraction. Splenocytes from control Xenopus, depleted of T cells by magnetic sorting and following culture in GFM, also developed natural cytotoxicity towards allotumour cells. Magnetic cell sorting also revealed that purified (CD5+) T cells cultured for 48 hours in GFM also became able to lyse the allogeneic tumour targets. Cytotoxicity mediated by T cells resided not only in the CD5+, CD8+ population, but also in the CD5+, CD8- (putative CD4+) T cell subset. Ontogenetic studies revealed that splenocytes from 6-7 week-old (stage 56-57) control larvae, even after 48 hr culture in GFM, were unable to spontaneously lyse the allotumour targets, whereas cultured splenocytes from 6 month old froglets were effective killers. Thymocytes from larvae or adults routinely failed to kill tumour cells. The work highlights the need to use Tx Xenopus to further explore non-T-cell-mediated, NK-like cytotoxicity at the amphibian level of evolution.
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Affiliation(s)
- T L Horton
- Department of Biological Sciences, University of Durham, UK
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Abstract
Amyloid plaques are the pathological hallmark of Alzheimer Disease (AD) brains, being found primarily in the hippocampus and neocortex, where AD pathology is most evident. Complement activation is associated with amyloid plaques which are made from fibrils of aggregated amyloid peptides, 39-42 amino acids long. In vitro studies show that aggregated amyloid peptides activate complement via the classical pathway, implying that amyloid plaques themselves cause complement activation in AD brains. In order to test this hypothesis, we sought to determine if a major peptide component of amyloid plaques, A beta 1-42, supports the formation of the classical pathway C3 convertase. Using normal human serum depleted of C3, we are able to detect C3 convertase activity on aggregated A beta 1-42 in vitro. The convertase activity is associated with the binding of C1q and activation of C4 on the aggregated peptide. Inhibitors of C1 esterase and the cation chelator EGTA both block the formation of the convertase activity. Congo red, a histochemical stain for amyloid deposits and an inhibitor of amyloid aggregation, reduces C3 convertase activity on aggregated A beta 1-42, indicated by decreased C3a production. Our results provide further evidence that aggregated A beta 1-42 alone is sufficient to serve as a nidus for complement activation, and thus may be involved directly in initiating the inflammation seen in AD brains.
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Affiliation(s)
- M R Emmerling
- Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Department of Pharmacology, Neuroscience Therapeutics, Ann Arbor, MI 48105, USA.
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Affiliation(s)
- T L Horton
- Department of Biological Sciences, University of Durham, U.K
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Horton TL, Ritchie P, Watson MD, Horton JD. NK-like activity against allogeneic tumour cells demonstrated in the spleen of control and thymectomized Xenopus. Immunol Cell Biol 1996; 74:365-73. [PMID: 8872188 DOI: 10.1038/icb.1996.64] [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: 02/02/2023]
Abstract
This paper addresses the issue of natural killer (NK) cell evolution by searching for NK-like activity in an amphibian representative, the immunologically well-characterized clawed frog, Xenopus laevis. Using in vitro 6 h 51chromium release assays, we have shown that splenocyte effectors from early thymectomized (Tx) year-old frogs, but not from control siblings, are able to spontaneously lyse allogeneic thymus tumour cell lines that lack MHC antigen expression. Such lytic capacity can be readily induced in control Xenopus and elevated in Tx frogs by a single injection of tumour cells, with maximal splenocyte cytotoxicity occurring 3 days postinjection, the amount of 51Cr-release correlating directly with effector: target ratios. Splenocytes, even those from tumour-injected frogs, are unable to lyse allogeneic splenic lymphoblasts or erythrocyte targets, even when the latter are coated with IgY (the Xenopus IgG equivalent); moreover, we were unable to demonstrate any splenocyte-induced lysis of the human NK cell target K562. Lymphokine-activated killing (LAK) in Xenopus is suggested, since Tx splenocytes cultured in cytokine-rich medium (from concanavalin A-stimulated control splenocytes) display significantly elevated killing of allogeneic tumour targets. Flow cytometric analysis highlights the loss of T cell markers from the spleen of Tx frogs and reveals a variable staining pattern of both control and Tx splenocytes when treated with a mAb that binds to both fish non-specific cytotoxic cells and human NK cells. Prospects for identifying the cellular basis of NK-like activity in Xenopus are discussed in the light of these experiments.
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Affiliation(s)
- T L Horton
- Department of Biological Sciences, University of Durham, UK
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Pöpping B, Gibbons T, Watson MD. The Pisum sativum MAP kinase homologue (PsMAPK) rescues the Saccharomyces cerevisiae hog1 deletion mutant under conditions of high osmotic stress. Plant Mol Biol 1996; 31:355-63. [PMID: 8756598 DOI: 10.1007/bf00021795] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Previous analysis of the MAP kinase homologue from Pisum sativum (PsMAPK) revealed a potential MAP kinase motif homologous to that found in eukaryotic cdc2 kinases. Sequence comparison showed a 47% identity on amino acid sequence basis to the Saccharomyces cerevisiae Hog1p MAP kinase involved in the osmoregulatory pathway. Under conditions of salt-stress aberrant morphology of a hog1 deletion mutant was completely restored and growth was partially restored by expression of the PsMAPK. This shows that PsMAPK is functionally active as a MAP kinase in S. cerevisiae. Comparison of PsMAPK with other kinases involved in osmosensitivity, showed a high degree of homology and implicates a possible role for PsMAPK in a P. sativum osmosensing signal transduction pathway.
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Affiliation(s)
- B Pöpping
- Department of Biological Sciences, University of Durham, UK
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Abstract
Compartment syndrome as a result of venous thrombosis is an uncommon occurrence. Generally, phlegmasia cerulea dolens or proximal venous thrombosis results in elevated compartment pressures. Distal venous occlusion rarely is reported as a cause of compartment syndrome. This is a case report of an otherwise healthy patient in whom popliteal vein thrombosis developed and resulted in elevation > 40 mm Hg of 3 leg muscle compartments requiring fasciotomies.
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Affiliation(s)
- T A VanFleet
- Division of Orthopaedics and Rehabilitation, Southern Illinois University School of Medicine, Springfield, USA
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Brown AP, Coleman J, Tommey AM, Watson MD, Slabas AR. Isolation and characterisation of a maize cDNA that complements a 1-acyl sn-glycerol-3-phosphate acyltransferase mutant of Escherichia coli and encodes a protein which has similarities to other acyltransferases. Plant Mol Biol 1994; 26:211-223. [PMID: 7948871 DOI: 10.1007/bf00039533] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We selected cDNA plasmid clones that corrected the temperature-sensitive phenotype of Escherichia coli strain JC201, which is deficient in 1-acyl-sn-glycerol-3-phosphate acyltransferase activity. A plasmid-based maize endosperm cDNA library was used for complementation and a plasmid that enabled the cells to grow at 44 degrees C on ampicillin was isolated. Addition of this plasmid (pMAT1) to JC201 restored 1-acyl-sn-glycerol-3-phosphate acyltransferase activity to the cells. Total phospholipid labelling showed that the substrate for the enzyme, lysophosphatidic acid, accumulated in JC201 and was further metabolised to phosphatidylethanolamine in complemented cells. Membranes isolated from such cells were able to convert lysophosphatidic acid to phosphatidic acid in acyltransferase assays. The cDNA insert of pMAT1 contains one long open reading frame of 374 amino acids which encodes a protein of relative molecular weight 42,543. The sequence of this protein is most similar to SLC1, which is thought to be able to acylate glycerol at the sn-2 position during synthesis of inositol-containing lipids. Homologies between the SLC1 protein, the 1-acyl-sn-glycerol-3-phosphate acyltransferase of E. coli (PlsC) and the maize ORF were found with blocks of conserved amino acids, whose spacing was conserved between the three proteins, identifiable.
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Affiliation(s)
- A P Brown
- Department of Biological Sciences, University of Durham, UK
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Cummins I, Hills MJ, Ross JH, Hobbs DH, Watson MD, Murphy DJ. Differential, temporal and spatial expression of genes involved in storage oil and oleosin accumulation in developing rapeseed embryos: implications for the role of oleosins and the mechanisms of oil-body formation. Plant Mol Biol 1993; 23:1015-27. [PMID: 8260622 DOI: 10.1007/bf00021816] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The temporal and spatial expression of oleosin and delta 9-stearoyl-ACP desaturase genes and their products has been examined in developing embryos of rapeseed, Brassica napus L. var. Topas. Expression of oleosin and stearate desaturase genes was measured by in situ hybridisation at five different stages of development ranging from the torpedo stage to a mature-desiccating embryo. The temporal pattern of gene expression varied dramatically between the two classes of gene. Stearate desaturase gene expression was relatively high, even at the torpedo stage, whereas oleosin gene expression was barely detectable at this stage. By the stage of maximum embryo fresh weight, stearate desaturase gene expression had declined considerably while oleosin gene expression was at its height. In contrast to their differential temporal expression, the in situ labelling of both classes of embryo-specific gene showed similar, relatively uniform patterns of spatial expression throughout the embryo sections. Immunogold labelling of ultra-thin sections from radicle tissue with anti-oleosin antibodies showed similar patterns to sections from cotyledon tissue. However, whereas at least three oleosin isoforms were detectable on western blots of homogenates from cotyledons, only one isoform was found in radicles. This suggests that some of the oleosin isoforms may be expressed differentially in the various types of embryo tissue. The differential timing of stearate desaturase and oleosin gene expression was mirrored by similar differences in the timing of the accumulation of their ultimate products, i.e. storage oil and oleosin proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- I Cummins
- Department of Brassica & Oilseeds Research, John Innes Centre, Norwich, UK
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37
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Abstract
Osmoadaptation in S. cerevisiae occurs through intracellular accumulation of glycerol in response to an increase in osmolarity of the surrounding environment. Analysis of ssv1-2, a strain carrying a mutation in a gene required for vacuole biogenesis, protein-sorting and osmohomeostasis, shows that the strain is terminally inactivated by 1.5 M NaCl within 10 seconds while the isogenic wild type maintains slow growth and accumulates glycerol within 18 hours. This study provides the first evidence that the vacuole participates in an immediate osmoregulatory process permitting survival until the osmoadaptive glycerol accumulation allows growth under osmotically unfavorable conditions.
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Affiliation(s)
- M Latterich
- Department of Biological Sciences, University of Durham, Great Britain
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Abstract
Oleosins of Brassica napus L. (oilseed rape) synthesized by in-vitro translation were found to be very efficiently targeted to microsomal membranes but only poorly translocated to oil bodies or emulsified oil. The use of other bilayer membranes as controls showed that this interaction was specific. The rate of oleosin synthesis in the presence of microsomes was enhanced about threefold, indicative of the involvement of the signal-recognition particle in the targeting process. There is no evidence for the cleavage of the protein during targeting and the protein sequence reveals no consensus cleavage site for the signal peptide. Protection experiments using Proteinase K revealed that about 6 kDa of the protein is exposed on the cytoplasmic side of the ER but the remainder is protected. Carbonate (pH 11) washing of microsomal membranes after in-vitro translation confirmed that oleosins have a domain which remains inserted in the ER rather than the protein being transported completely into the lumen of the ER. These results indicate that oleosins are transported via the ER prior to their accumulation on oil bodies.
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Affiliation(s)
- M J Hills
- Department of Brassica and Oilseeds Research, John Innes Centre, Norwich, UK
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Abstract
The yeast vacuole plays an important role in nitrogen metabolism, storage and intracellular macromolecular degradation. Evidence suggests that it is also involved in osmohomeostasis of the cell. We have taken a mutational approach for the analysis of vacuolar function and biogenesis by the isolation of 97 mutants unable to grow if high concentrations of salt are present in the medium. Phenotypic analysis was able to demonstrate that apart from osmosensitivity the mutations also conferred other properties such as altered vacuolar morphology and secretion of the vacuolar enzymes carboxypeptidase Y, proteinase A, proteinase B and alpha-mannosidase. The mutants fall into at least 17 complementation groups, termed ssv for salt-sensitive vacuolar mutants, of which two are identical to complementation groups isolated by others. We conclude that in Saccharomyces cerevisiae correct vacuolar biogenesis and protein targeting is required for osmotolerance as well as other important cellular processes.
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Affiliation(s)
- M Latterich
- Department of Biological Sciences, Durham University, UK
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Munoz Aguilar JM, Ashby AM, Richards AJM, Loake GJ, Watson MD, Shaw CH. Chemotaxis of Rhizobium leguminosarum biovar phaseoli towards Flavonoid Inducers of the Symbiotic Nodulation Genes. Microbiology (Reading) 1988. [DOI: 10.1099/00221287-134-10-2741] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Ashby AM, Watson MD, Loake GJ, Shaw CH. Ti plasmid-specified chemotaxis of Agrobacterium tumefaciens C58C1 toward vir-inducing phenolic compounds and soluble factors from monocotyledonous and dicotyledonous plants. J Bacteriol 1988; 170:4181-7. [PMID: 3410827 PMCID: PMC211426 DOI: 10.1128/jb.170.9.4181-4187.1988] [Citation(s) in RCA: 98] [Impact Index Per Article: 2.7] [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: 01/05/2023] Open
Abstract
Twelve phenolic compounds with related structures were analyzed for their ability to act as chemoattractants for Agrobacterium tumefaciens C58C1 and as inducers of the Ti plasmid virulence operons. The results divided the phenolic compounds into three groups: compounds that act as strong vir inducers and are chemoattractants for A. tumefaciens C58C1 harboring the nopaline Ti plasmid pDUB1003 delta 31, but not the isogenic cured strain; compounds that are at best weak vir inducers and are weak chemoattractants for Ti plasmid-harboring and cured A. tumefaciens C58C1; and compounds that are vir noninducers and are also nonattractants. A strong correlation between vir-inducing ability and Ti plasmid requirement for chemotaxis is thus established. In addition, chemical structure rules for vir induction and chemotaxis are outlined. Positive chemotaxis toward root and shoot homogenates from monocotyledonous and dicotyledonous plants was observed. At low extract concentrations, chemotaxis was enhanced by the presence of Ti plasmid. The chemoattractants do not derive from intact cell walls. Lack of attraction is not responsible for the apparent block to monocot transformation by A. tumefaciens.
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Affiliation(s)
- A M Ashby
- Department of Botany, University of Durham, England
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42
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Watson MD, Kaye JJ. Traumatic venous aneurysm presenting as a ganglion cyst. A case report. J Bone Joint Surg Am 1988; 70:1248-50. [PMID: 3417711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- M D Watson
- Department of Orthopaedic Surgery, Ochsner Clinic, New Orleans, Louisiana 70121
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Watson MD, Lambert N, Delauney A, Yarwood JN, Croy RR, Gatehouse JA, Wright DJ, Boulter D. Isolation and expression of a pea vicilin cDNA in the yeast Saccharomyces cerevisiae. Biochem J 1988; 251:857-64. [PMID: 3046604 PMCID: PMC1149081 DOI: 10.1042/bj2510857] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [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: 01/03/2023]
Abstract
A cDNA clone containing the complete coding sequence for vicilin from pea (Pisum sativum L.) was isolated. It specifies a 50,000-Mr protein that in pea is neither post-translationally processed nor glycosylated. The cDNA clone was expressed in yeast from a 2 micron plasmid by using the yeast phosphoglycerate kinase promoter and initiator codon. The resultant fusion protein, which contains the first 16 amino acid residues of phosphoglycerate kinase in addition to the vicilin sequence, was purified and subsequently characterized. It has slightly slower mobility on SDS/polyacrylamide-gel electrophoresis than standard pea vicilin and forms a mixture of multimers, some of which resemble the native protein.
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Affiliation(s)
- M D Watson
- Department of Botany, University of Durham, U.K
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Abstract
Two hundred fifty-seven high school track athletes from 17 teams were observed prospectively for one complete season (77 days) to study the incidence and types of injuries and to establish the relationship among injuries, duration of training, and individual performance ability. One hundred seventy-four (68%) of the athletes were male and 83 (33%) were female. A total of 41 injuries was observed over this period of time. One injury occurred for every 5.8 males and every 7.5 females. On the average, an injury resulted in 8.1 days of missed practice, 8.7 days for males and 6.6 days for females. Sprinting events were responsible for 46% of all injuries. The majority (83%) of injuries involved the lower extremities. Management of these injuries varied greatly. A direct correlation was noted between performance level of the athlete and incidence of injuries. The average noninjured athlete ranked at the 57.4 percentile based on best seasonal performance while the average injured athlete ranked at the 75.4 percentile. This direct relationship was present for both sexes and within all events, although some variation was noted within these separate groups.
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Abstract
This paper describes the first functional map of a promoter expressed from the plant chromosome. We have constructed a series of overlapping deletion mutants within the region upstream of the Ti-plasmid encoded nopaline synthase (nos) gene. By monitoring nos expression in tumour tissue we have inferred a functional map of the nos promoter. The maximum length of sequence upstream of the transcription initiation point required to express wild type levels of nopaline synthase is 88 bp. Within this region, the "CAAT" box is essential for maximal activity; deletion of this sequence reduced apparent nos expression by over 80%. Presence of an intact or partial "TATA" box in the absence of the "CAAT" box supports a barely detectable level of nopaline synthase. Removal of all sequences upstream of the nos coding sequence results in no detectable activity.
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Shaw CH, Watson MD, Carter GH, Shaw CH. The right hand copy of the nopaline Ti-plasmid 25 bp repeat is required for tumour formation. Nucleic Acids Res 1984; 12:6031-41. [PMID: 6473100 PMCID: PMC320054 DOI: 10.1093/nar/12.15.6031] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
At either end of the nopaline Ti-plasmid T-region resides a copy of a 25 bp repeated element. The normal T-DNA endpoint is 1 bp internal of the right copy, with the transcription initiation site of the nopaline synthase (nos) gene being approximately 300 bp away in the same direction. Here we describe results which demonstrate that deletion of any combination of sequences between the nos initiation site and the right copy of the 25 bp repeat does not affect oncogenicity. Thus a mutant retaining the right copy and only 3 bp internal of it is indistinguishable from the wild type parent in its oncogenic properties. However deletion of a further 39 bp, including complete removal of the right copy abolishes crown gall tumour formation on Kalanchöe and tobacco. From these results we infer that unlike the left border, the right copy of the 25 bp repeat is required for T-DNA transfer and/or integration. This is the first conclusive demonstration of the involvement of a copy of the repeats in this process.
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Watson MD, Scaife JG. Integrative compatibility: stable coexistence of chromosomally integrated and autonomous derivatives of plasmid RP4. J Bacteriol 1980; 142:462-6. [PMID: 6991474 PMCID: PMC294003 DOI: 10.1128/jb.142.2.462-466.1980] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
P group plasmid RP4 lambda att has a novel feature. Its incompatibility function is phenotypically switched off when it integrates into the bacterial chromosome.
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Watson MD, Wild J, Umbarger HE. Positive control of ilvC expression in Escherichia coli K-12; identification and mapping of regulatory gene ilvY. J Bacteriol 1979; 139:1014-20. [PMID: 113381 PMCID: PMC218050 DOI: 10.1128/jb.139.3.1014-1020.1979] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The construction of a plasmid carrying the ilvC::lacZ fusion is described. This plasmid provides a convenient source of template deoxyribonucleic acid for use in an in vitro protein-synthesizing system. We screened strains deleted in regions of the ilv cluster for their ability to support ilvC-dependent beta-galactosidase synthesis. The fact that two deletions prevented beta-galactosidase production indicated that ilv-C expression is under positive control. By use of plasmids carrying the positive-control factor structural gene ilvY, we were able to restore protein-synthesizing ability to these strains. These plasmids also enabled us to map ilvY between ilvA and ilvC.
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