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Jalali-Mola Z, Grass T, Kasper V, Lewenstein M, Bhattacharya U. Topological Bogoliubov Quasiparticles from Bose-Einstein Condensate in a Flat Band System. Phys Rev Lett 2023; 131:226601. [PMID: 38101336 DOI: 10.1103/physrevlett.131.226601] [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: 03/09/2023] [Revised: 09/07/2023] [Accepted: 10/23/2023] [Indexed: 12/17/2023]
Abstract
For bosons with flat energy dispersion, condensation can occur in different symmetry sectors. Here, we consider bosons in a kagome lattice with π-flux hopping, which, in the presence of mean-field interactions, exhibit degenerate condensates in the Γ and the K point. We analyze the excitation above both condensates and find strikingly different properties: For the K-point condensate, the Bogoliubov-de Gennes (BdG) Hamiltonian has broken particle-hole symmetry and exhibits a topologically trivial quasiparticle band structure. However, band flatness plays a key role in breaking the time-reversal symmetry of the BdG Hamiltonian for a Γ-point condensate. Consequently, its quasiparticle band structure exhibits nontrivial topology, characterized by nonzero Chern numbers and by the presence of edge states. Although quantum fluctuations energetically favor the K-point condensate, the interesting properties of the Γ-point condensate become relevant for anisotropic hopping. The topological properties of the Γ-point condensate get even richer in the presence of extended Bose-Hubbard interactions. We find a topological phase transition into a topological condensate characterized by high Chern number and also comment on the realization and detection of such excitations.
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Affiliation(s)
- Zahra Jalali-Mola
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Tobias Grass
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- DIPC-Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
- Ikerbasque-Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain
| | - Valentin Kasper
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- Nord Quantique, 3000 boulevard de l'Université (P1-ACET), Sherbrooke J1K 0A5, Quebec, Canada
| | - Maciej Lewenstein
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA, Passeig de Lluís Companys 23, 08010 Barcelona, Spain
| | - Utso Bhattacharya
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
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Buchner F, Dokuzluoglu Z, Grass T, Rodriguez-Muela N. Spinal Cord Organoids to Study Motor Neuron Development and Disease. Life (Basel) 2023; 13:1254. [PMID: 37374039 DOI: 10.3390/life13061254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 05/18/2023] [Indexed: 06/29/2023] Open
Abstract
Motor neuron diseases (MNDs) are a heterogeneous group of disorders that affect the cranial and/or spinal motor neurons (spMNs), spinal sensory neurons and the muscular system. Although they have been investigated for decades, we still lack a comprehensive understanding of the underlying molecular mechanisms; and therefore, efficacious therapies are scarce. Model organisms and relatively simple two-dimensional cell culture systems have been instrumental in our current knowledge of neuromuscular disease pathology; however, in the recent years, human 3D in vitro models have transformed the disease-modeling landscape. While cerebral organoids have been pursued the most, interest in spinal cord organoids (SCOs) is now also increasing. Pluripotent stem cell (PSC)-based protocols to generate SpC-like structures, sometimes including the adjacent mesoderm and derived skeletal muscle, are constantly being refined and applied to study early human neuromuscular development and disease. In this review, we outline the evolution of human PSC-derived models for generating spMN and recapitulating SpC development. We also discuss how these models have been applied to exploring the basis of human neurodevelopmental and neurodegenerative diseases. Finally, we provide an overview of the main challenges to overcome in order to generate more physiologically relevant human SpC models and propose some exciting new perspectives.
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Affiliation(s)
- Felix Buchner
- German Center for Neurodegenerative Diseases, 01307 Dresden, Germany
| | | | - Tobias Grass
- German Center for Neurodegenerative Diseases, 01307 Dresden, Germany
| | - Natalia Rodriguez-Muela
- German Center for Neurodegenerative Diseases, 01307 Dresden, Germany
- Center for Regenerative Therapies Dresden, Technische Universität Dresden, 01307 Dresden, Germany
- Max Planck Institute for Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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3
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Cao B, Grass T, Gazzano O, Patel KA, Hu J, Müller M, Huber-Loyola T, Anzi L, Watanabe K, Taniguchi T, Newell DB, Gullans M, Sordan R, Hafezi M, Solomon GS. Chiral Transport of Hot Carriers in Graphene in the Quantum Hall Regime. ACS Nano 2022; 16:18200-18209. [PMID: 36326218 PMCID: PMC9706666 DOI: 10.1021/acsnano.2c05502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 09/26/2022] [Indexed: 06/16/2023]
Abstract
Photocurrent (PC) measurements can reveal the relaxation dynamics of photoexcited hot carriers beyond the linear response of conventional transport experiments, a regime important for carrier multiplication. Here, we study the relaxation of carriers in graphene in the quantum Hall regime by accurately measuring the PC signal and modeling the data using optical Bloch equations. Our results lead to a unified understanding of the relaxation processes in graphene over different magnetic field strength regimes, which is governed by the interplay of Coulomb interactions and interactions with acoustic and optical phonons. Our data provide clear indications of a sizable carrier multiplication. Moreover, the oscillation pattern and the saturation behavior of PC are manifestations of not only the chiral transport properties of carriers in the quantum Hall regime but also the chirality change at the Dirac point, a characteristic feature of a relativistic quantum Hall effect.
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Affiliation(s)
- Bin Cao
- Joint
Quantum Institute, NIST/University of Maryland, College Park, Maryland20742, United States
| | - Tobias Grass
- Joint
Quantum Institute, NIST/University of Maryland, College Park, Maryland20742, United States
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, Castelldefels
(Barcelona) 08860, Spain
- DIPC—Donostia
International Physics Center, San
Sebastian20018, Spain
- Ikerbasque—Basque Foundation for Science, Bilbao48013, Spain
| | - Olivier Gazzano
- Joint
Quantum Institute, NIST/University of Maryland, College Park, Maryland20742, United States
| | | | - Jiuning Hu
- National
Institute of Standards and Technology, Gaithersburg, Maryland20878, United States
| | - Markus Müller
- Joint
Quantum Institute, NIST/University of Maryland, College Park, Maryland20742, United States
| | - Tobias Huber-Loyola
- Joint
Quantum Institute, NIST/University of Maryland, College Park, Maryland20742, United States
| | - Luca Anzi
- L-NESS,
Department of Physics, Politecnico di Milano, Via Anzani 42, 22100Como, Italy
| | - Kenji Watanabe
- National
Institute for Materials Science, 1-1 Namiki, 305-0044Tsukuba, Japan
| | - Takashi Taniguchi
- National
Institute for Materials Science, 1-1 Namiki, 305-0044Tsukuba, Japan
| | - David B. Newell
- National
Institute of Standards and Technology, Gaithersburg, Maryland20878, United States
| | - Michael Gullans
- Joint
Center for Quantum Information and Computer Science, NIST/University of Maryland, College
Park, Maryland20742, United States
| | - Roman Sordan
- L-NESS,
Department of Physics, Politecnico di Milano, Via Anzani 42, 22100Como, Italy
| | - Mohammad Hafezi
- Joint
Quantum Institute, NIST/University of Maryland, College Park, Maryland20742, United States
- IREAP, University
of Maryland, College Park, Maryland20742, United States
| | - Glenn S. Solomon
- Joint
Quantum Institute, NIST/University of Maryland, College Park, Maryland20742, United States
- Department
of Physics and IPAS, University of Adelaide, Adelaide, South Australia5005, Australia
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Lansing F, Mukhametzyanova L, Rojo-Romanos T, Iwasawa K, Kimura M, Paszkowski-Rogacz M, Karpinski J, Grass T, Sonntag J, Schneider PM, Günes C, Hoersten J, Schmitt LT, Rodriguez-Muela N, Knöfler R, Takebe T, Buchholz F. Correction of a Factor VIII genomic inversion with designer-recombinases. Nat Commun 2022; 13:422. [PMID: 35058465 PMCID: PMC8776779 DOI: 10.1038/s41467-022-28080-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 12/22/2021] [Indexed: 01/16/2023] Open
Abstract
Despite advances in nuclease-based genome editing technologies, correcting human disease-causing genomic inversions remains a challenge. Here, we describe the potential use of a recombinase-based system to correct the 140 kb inversion of the F8 gene frequently found in patients diagnosed with severe Hemophilia A. Employing substrate-linked directed molecular evolution, we develop a coupled heterodimeric recombinase system (RecF8) achieving 30% inversion of the target sequence in human tissue culture cells. Transient RecF8 treatment of endothelial cells, differentiated from patient-derived induced pluripotent stem cells (iPSCs) of a hemophilic donor, results in 12% correction of the inversion and restores Factor VIII mRNA expression. In this work, we present designer-recombinases as an efficient and specific means towards treatment of monogenic diseases caused by large gene inversions. Correction of disease-causing large genomic inversions remains challenging. Here, the authors developed a dual designer-recombinase system (RecF8) that efficiently corrects a 140 kb inversion frequently found in patients with severe Hemophilia A.
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Bhattacharya U, Grass T, Bachtold A, Lewenstein M, Pistolesi F. Phonon-Induced Pairing in Quantum Dot Quantum Simulator. Nano Lett 2021; 21:9661-9667. [PMID: 34757742 PMCID: PMC8631338 DOI: 10.1021/acs.nanolett.1c03457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 11/03/2021] [Indexed: 06/13/2023]
Abstract
Quantum simulations can provide new insights into the physics of strongly correlated electronic systems. A well-studied system, but still open in many regards, is the Hubbard-Holstein Hamiltonian, where electronic repulsion is in competition with attraction generated by the electron-phonon coupling. In this context, we study the behavior of four quantum dots in a suspended carbon nanotube and coupled to its flexural degrees of freedom. The system is described by a Hamiltonian of the Hubbard-Holstein class, where electrons on different sites interact with the same phonon. We find that the system presents a transition from the Mott insulating state to a polaronic state, with the appearance of pairing correlations and the breaking of the translational symmetry. These findings will motivate further theoretical and experimental efforts to employ nanoelectromechanical systems to simulate strongly correlated systems with electron-phonon interactions.
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Affiliation(s)
- Utso Bhattacharya
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, Castelldefels, Barcelona 08860, Spain
- Max-Planck-Institut
für Quantenoptik, D-85748 Garching, Germany
| | - Tobias Grass
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Adrian Bachtold
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, Castelldefels, Barcelona 08860, Spain
| | - Maciej Lewenstein
- ICFO-Institut
de Ciencies Fotoniques, The Barcelona Institute
of Science and Technology, Castelldefels, Barcelona 08860, Spain
- ICREA, Pg. Lluis Companys
23, 08010 Barcelona, Spain
| | - Fabio Pistolesi
- Univ.
Bordeaux, CNRS, LOMA, UMR 5798, F-33400 Talence, France
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Rodriguez-Muela N, Parkhitko A, Grass T, Gibbs RM, Norabuena EM, Perrimon N, Singh R, Rubin LL. Blocking p62-dependent SMN degradation ameliorates spinal muscular atrophy disease phenotypes. J Clin Invest 2018; 128:3008-3023. [PMID: 29672276 DOI: 10.1172/jci95231] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 04/12/2018] [Indexed: 12/13/2022] Open
Abstract
Spinal muscular atrophy (SMA), a degenerative motor neuron (MN) disease, caused by loss of functional survival of motor neuron (SMN) protein due to SMN1 gene mutations, is a leading cause of infant mortality. Increasing SMN levels ameliorates the disease phenotype and is unanimously accepted as a therapeutic approach for patients with SMA. The ubiquitin/proteasome system is known to regulate SMN protein levels; however, whether autophagy controls SMN levels remains poorly explored. Here, we show that SMN protein is degraded by autophagy. Pharmacological and genetic inhibition of autophagy increases SMN levels, while induction of autophagy decreases these levels. SMN degradation occurs via its interaction with the autophagy adapter p62 (also known as SQSTM1). We also show that SMA neurons display reduced autophagosome clearance, increased p62 and ubiquitinated proteins levels, and hyperactivated mTORC1 signaling. Importantly, reducing p62 levels markedly increases SMN and its binding partner gemin2, promotes MN survival, and extends lifespan in fly and mouse SMA models, revealing p62 as a potential new therapeutic target for the treatment of SMA.
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Affiliation(s)
- Natalia Rodriguez-Muela
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Andrey Parkhitko
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Tobias Grass
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Rebecca M Gibbs
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Erika M Norabuena
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA.,Howard Hughes Medical Institute, Boston, Massachusetts, USA
| | - Rajat Singh
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
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Grass T, Wahn U. [The allergy syndrome in childhood. Immunologic principles--risk factors--prevention]. Monatsschr Kinderheilkd 1991; 139:316-22. [PMID: 1832740] [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: 12/29/2022]
Abstract
The time of manifestation, severity and clinical course of atopic diseases are primarily determined by genetic factors. However, a number of environmental influences, like exposure to allergens and adjuvant trigger factors are modulating the clinical course. The risk for atopic disease can be predicted from cord blood IgE levels and the atopic family history of first degree relatives. Since no predictor is of sufficient sensitivity and specificity, there is a need for further predictors of atopy. Different prevention strategies, i.e. effect of early infant diet and maternal food avoidance during pregnancy or lactation are discussed.
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Affiliation(s)
- T Grass
- Kinderklinik, Freien Universität Berlin
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Affiliation(s)
- K E Bergmann
- Federal Health Office, Free University, Berlin, Germany
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