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Golfier S, Quail T, Brugués J. Single-Molecule Approaches to Study DNA Condensation. Methods Mol Biol 2024; 2740:1-19. [PMID: 38393466 DOI: 10.1007/978-1-0716-3557-5_1] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
Proteins drive genome compartmentalization across different length scales. While the identities of these proteins have been well-studied, the physical mechanisms that drive genome organization have remained largely elusive. Studying these mechanisms is challenging owing to a lack of methodologies to parametrize physical models in cellular contexts. Furthermore, because of the complex, entangled, and dense nature of chromatin, conventional live imaging approaches often lack the spatial resolution to dissect these principles. In this chapter, we will describe how to image the interactions of λ-DNA with proteins under purified and cytoplasmic conditions. First, we will outline how to prepare biotinylated DNA, functionalize coverslips with biotin-conjugated poly-ethylene glycol (PEG), and assemble DNA microchannels compatible for the imaging of protein-DNA interactions using total internal fluorescence microscopy. Then we will describe experimental methods to image protein-DNA interactions in vitro and DNA loop extrusion using Xenopus laevis egg extracts.
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Affiliation(s)
- Stefan Golfier
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
- Center for Systems Biology Dresden, Dresden, Germany
- B CUBE, Center for Molecular Bioengineering, TU Dresden, Dresden, Germany
| | - Thomas Quail
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
- Center for Systems Biology Dresden, Dresden, Germany
- EMBL Heidelberg, Cell Biology and Biophysics Unit, Heidelberg, Germany
| | - Jan Brugués
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
- Center for Systems Biology Dresden, Dresden, Germany.
- Physics of Life, TU Dresden, Dresden, Germany.
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2
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Siegel F, Siegel S, Graham K, Karsli-Uzunbas G, Korr D, Schroeder J, Boemer U, Hillig R, Mortier J, Niehues M, Golfier S, Schulze V, Menz S, Kamburov A, Hermsen M, Cherniak A, Eis K, Eheim A, Meyerson M, Greulich H. BAY 2927088: The first non-covalent, potent, and selective tyrosine kinase inhibitor targeting EGFR exon 20 insertions and C797S resistance mutations in NSCLC. Eur J Cancer 2022. [DOI: 10.1016/s0959-8049(22)00827-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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3
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Chang CY, Vila JCC, Bender M, Li R, Mankowski MC, Bassette M, Borden J, Golfier S, Sanchez PGL, Waymack R, Zhu X, Diaz-Colunga J, Estrela S, Rebolleda-Gomez M, Sanchez A. Engineering complex communities by directed evolution. Nat Ecol Evol 2021; 5:1011-1023. [PMID: 33986540 PMCID: PMC8263491 DOI: 10.1038/s41559-021-01457-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 03/28/2021] [Indexed: 02/03/2023]
Abstract
Directed evolution has been used for decades to engineer biological systems at or below the organismal level. Above the organismal level, a small number of studies have attempted to artificially select microbial ecosystems, with uneven and generally modest success. Our theoretical understanding of artificial ecosystem selection is limited, particularly for large assemblages of asexual organisms, and we know little about designing efficient methods to direct their evolution. Here, we have developed a flexible modelling framework that allows us to systematically probe any arbitrary selection strategy on any arbitrary set of communities and selected functions. By artificially selecting hundreds of in silico microbial metacommunities under identical conditions, we first show that the main breeding methods used to date, which do not necessarily let communities reach their ecological equilibrium, are outperformed by a simple screen of sufficiently mature communities. We then identify a range of alternative directed evolution strategies that, particularly when applied in combination, are well suited for the top-down engineering of large, diverse and stable microbial consortia. Our results emphasize that directed evolution allows an ecological structure-function landscape to be navigated in search of dynamically stable and ecologically resilient communities with desired quantitative attributes.
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Affiliation(s)
- Chang-Yu Chang
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
| | - Jean C C Vila
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
| | - Madeline Bender
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
| | - Richard Li
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
| | - Madeleine C Mankowski
- Department of Immunobiology and Department of Laboratory Medicine, Yale University, New Haven, CT, USA
| | - Molly Bassette
- Biomedical Sciences Graduate Program, University of California San Francisco, San Francisco, CA, USA
| | - Julia Borden
- Department of Molecular & Cellular Biology, University of California Berkeley, Berkeley, CA, USA
| | - Stefan Golfier
- Max Planck Institute of Molecular Cell Biology and Genetics, and Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Paul Gerald L Sanchez
- European Molecular Biology Laboratory (EMBL), Developmental Biology Unit, Heidelberg, Germany
| | - Rachel Waymack
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, CA, USA
| | - Xinwen Zhu
- Department of Biomedical Engineering and the Biological Design Center, Boston University, Boston, MA, USA
| | - Juan Diaz-Colunga
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
| | - Sylvie Estrela
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
| | - Maria Rebolleda-Gomez
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA
- Microbial Sciences Institute, Yale University, New Haven, CT, USA
| | - Alvaro Sanchez
- Department of Ecology & Evolutionary Biology, Yale University, New Haven, CT, USA.
- Microbial Sciences Institute, Yale University, New Haven, CT, USA.
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Rieckhoff EM, Berndt F, Elsner M, Golfier S, Decker F, Ishihara K, Brugués J. Spindle Scaling Is Governed by Cell Boundary Regulation of Microtubule Nucleation. Curr Biol 2020; 30:4973-4983.e10. [DOI: 10.1016/j.cub.2020.10.093] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 10/11/2020] [Accepted: 10/29/2020] [Indexed: 02/08/2023]
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Abstract
Loop extrusion by structural maintenance of chromosomes (SMC) complexes has been proposed as a mechanism to organize chromatin in interphase and metaphase. However, the requirements for chromatin organization in these cell cycle phases are different, and it is unknown whether loop extrusion dynamics and the complexes that extrude DNA also differ. Here, we used Xenopus egg extracts to reconstitute and image loop extrusion of single DNA molecules during the cell cycle. We show that loops form in both metaphase and interphase, but with distinct dynamic properties. Condensin extrudes DNA loops non-symmetrically in metaphase, whereas cohesin extrudes loops symmetrically in interphase. Our data show that loop extrusion is a general mechanism underlying DNA organization, with dynamic and structural properties that are biochemically regulated during the cell cycle.
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Affiliation(s)
- Stefan Golfier
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Max Planck Institute for the Physics of Complex SystemsDresdenGermany
- Centre for Systems Biology DresdenDresdenGermany
- Cluster of Excellence Physics of Life, TU DresdenDresdenGermany
| | - Thomas Quail
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Max Planck Institute for the Physics of Complex SystemsDresdenGermany
- Centre for Systems Biology DresdenDresdenGermany
- Cluster of Excellence Physics of Life, TU DresdenDresdenGermany
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of TechnologyYokohamaJapan
| | - Jan Brugués
- Max Planck Institute of Molecular Cell Biology and GeneticsDresdenGermany
- Max Planck Institute for the Physics of Complex SystemsDresdenGermany
- Centre for Systems Biology DresdenDresdenGermany
- Cluster of Excellence Physics of Life, TU DresdenDresdenGermany
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6
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Rodenfels J, Sartori P, Golfier S, Nagendra K, Neugebauer KM, Howard J. Contribution of increasing plasma membrane to the energetic cost of early zebrafish embryogenesis. Mol Biol Cell 2020; 31:520-526. [PMID: 32049586 PMCID: PMC7202076 DOI: 10.1091/mbc.e19-09-0529] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 01/27/2020] [Accepted: 02/07/2020] [Indexed: 12/20/2022] Open
Abstract
How do early embryos allocate the resources stored in the sperm and egg? Recently, we established isothermal calorimetry to measure heat dissipation by living zebra-fish embryos and to estimate the energetics of specific developmental events. During the reductive cleavage divisions, the rate of heat dissipation increases from ∼60 nJ · s-1 at the two-cell stage to ∼90 nJ · s-1 at the 1024-cell stage. Here we ask which cellular process(es) drive this increasing energetic cost. We present evidence that the cost is due to the increase in the total surface area of all the cells of the embryo. First, embryo volume stays constant during the cleavage stage, indicating that the increase is not due to growth. Second, the heat increase is blocked by nocodazole, which inhibits DNA replication, mitosis, and cell division; this suggests some aspect of cell proliferation contributes to these costs. Third, the heat increases in proportion to the total cell surface area rather than total cell number. Fourth, the heat increase falls within the range of the estimated costs of maintaining and assembling plasma membranes and associated proteins. Thus, the increase in total plasma membrane associated with cell proliferation is likely to contribute appreciably to the total energy budget of the embryo.
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Affiliation(s)
- Jonathan Rodenfels
- Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511
- Marine Biological Laboratory, Woods Hole, MA 02543
| | - Pablo Sartori
- Marine Biological Laboratory, Woods Hole, MA 02543
- Simons Center for Systems Biology, School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540
- Center for Studies in Physics and Biology and Laboratory of Living Matter, Rockefeller University, New York, NY 10065
| | - Stefan Golfier
- Marine Biological Laboratory, Woods Hole, MA 02543
- Max Planck Institute Cell of Molecular Cell Biology and Genetics, Dresden, 01307 Germany
| | - Kartikeya Nagendra
- Marine Biological Laboratory, Woods Hole, MA 02543
- Center for Soft Matter Research, Department of Physics, New York University, New York, NY 10003
| | - Karla M. Neugebauer
- Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511
- Marine Biological Laboratory, Woods Hole, MA 02543
| | - Jonathon Howard
- Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511
- Marine Biological Laboratory, Woods Hole, MA 02543
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7
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Golfier S, Rosendahl P, Mietke A, Herbig M, Guck J, Otto O. High-throughput cell mechanical phenotyping for label-free titration assays of cytoskeletal modifications. Cytoskeleton (Hoboken) 2017; 74:283-296. [PMID: 28445605 PMCID: PMC5601209 DOI: 10.1002/cm.21369] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 04/12/2017] [Accepted: 04/20/2017] [Indexed: 01/29/2023]
Abstract
The mechanical fingerprint of cells is inherently linked to the structure of the cytoskeleton and can serve as a label‐free marker for cell homeostasis or pathologic states. How cytoskeletal composition affects the physical response of cells to external loads has been intensively studied with a spectrum of techniques, yet quantitative and statistically powerful investigations in the form of titration assays are hampered by the low throughput of most available methods. In this study, we employ real‐time deformability cytometry (RT‐DC), a novel microfluidic tool to examine the effects of biochemically modified F‐actin and microtubule stability and nuclear chromatin structure on cell deformation in a human leukemia cell line (HL60). The high throughput of our method facilitates extensive titration assays that allow for significance assessment of the observed effects and extraction of half‐maximal concentrations for most of the applied reagents. We quantitatively show that integrity of the F‐actin cortex and microtubule network dominate cell deformation on millisecond timescales probed with RT‐DC. Drug‐induced alterations in the nuclear chromatin structure were not found to consistently affect cell deformation. The sensitivity of the high‐throughput cell mechanical measurements to the cytoskeletal modifications we present in this study opens up new possibilities for label‐free dose‐response assays of cytoskeletal modifications.
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Affiliation(s)
- Stefan Golfier
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany.,Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max-Planck-Institute for Physics of Complex Systems, Dresden, Germany
| | - Philipp Rosendahl
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Alexander Mietke
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Max-Planck-Institute for Physics of Complex Systems, Dresden, Germany
| | - Maik Herbig
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Jochen Guck
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Oliver Otto
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany.,ZIK HIKE, Universität Greifswald, Greifswald, Germany
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Otto O, Rosendahl P, Golfier S, Mietke A, Herbig M, Jacobi A, Topfner N, Herold C, Klaue D, Girardo S, Winzi M, Fischer-Friedrich E, Guck J. Real-time deformability cytometry as a label-free indicator of cell function. Annu Int Conf IEEE Eng Med Biol Soc 2016; 2015:1861-4. [PMID: 26736644 DOI: 10.1109/embc.2015.7318744] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The mechanical properties of cells are known to be a label-free, inherent marker of biological function in health and disease. Wide-spread utilization has so far been impeded by the lack of a convenient measurement technique with sufficient throughput. To address this unmet need, we have recently introduced real-time deformability cytometry (RT-DC) for continuous mechanical single-cell classification of heterogeneous cell populations at rates of several hundred cells per second. Cells are driven through the constriction zone of a microfluidic chip leading to cell deformations due to hydrodynamic stresses only. Our custom-built image processing software performs image acquisition, image analysis and data storage on the fly. The ensuing deformations can be quantified and an analytical model enables the derivation of cell material properties. Performing RT-DC we highlight its potential to identify rare objects in heterogeneous suspensions and to track drug-induced changes in cells. In summary, RT-DC enables marker-free, quantitative phenotyping of heterogeneous cell populations with a throughput comparable to standard flow cytometry.
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9
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Mietke A, Otto O, Girardo S, Rosendahl P, Taubenberger A, Golfier S, Ulbricht E, Aland S, Guck J, Fischer-Friedrich E. Extracting Cell Stiffness from Real-Time Deformability Cytometry: Theory and Experiment. Biophys J 2016; 109:2023-36. [PMID: 26588562 PMCID: PMC4656812 DOI: 10.1016/j.bpj.2015.09.006] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [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: 04/27/2015] [Revised: 07/09/2015] [Accepted: 09/04/2015] [Indexed: 12/12/2022] Open
Abstract
Cell stiffness is a sensitive indicator of physiological and pathological changes in cells, with many potential applications in biology and medicine. A new method, real-time deformability cytometry, probes cell stiffness at high throughput by exposing cells to a shear flow in a microfluidic channel, allowing for mechanical phenotyping based on single-cell deformability. However, observed deformations of cells in the channel not only are determined by cell stiffness, but also depend on cell size relative to channel size. Here, we disentangle mutual contributions of cell size and cell stiffness to cell deformation by a theoretical analysis in terms of hydrodynamics and linear elasticity theory. Performing real-time deformability cytometry experiments on both model spheres of known elasticity and biological cells, we demonstrate that our analytical model not only predicts deformed shapes inside the channel but also allows for quantification of cell mechanical parameters. Thereby, fast and quantitative mechanical sampling of large cell populations becomes feasible.
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Affiliation(s)
- Alexander Mietke
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Oliver Otto
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Salvatore Girardo
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Philipp Rosendahl
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Anna Taubenberger
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Stefan Golfier
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Elke Ulbricht
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Sebastian Aland
- Institute of Scientific Computing, Technische Universität Dresden, Dresden, Germany
| | - Jochen Guck
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Elisabeth Fischer-Friedrich
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany; Max Planck Institute for the Physics of Complex Systems, Dresden, Germany.
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Chan CJ, Ekpenyong AE, Golfier S, Li W, Chalut KJ, Otto O, Elgeti J, Guck J, Lautenschläger F. Myosin II Activity Softens Cells in Suspension. Biophys J 2015; 108:1856-69. [PMID: 25902426 PMCID: PMC4407259 DOI: 10.1016/j.bpj.2015.03.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 02/26/2015] [Accepted: 03/04/2015] [Indexed: 01/08/2023] Open
Abstract
The cellular cytoskeleton is crucial for many cellular functions such as cell motility and wound healing, as well as other processes that require shape change or force generation. Actin is one cytoskeleton component that regulates cell mechanics. Important properties driving this regulation include the amount of actin, its level of cross-linking, and its coordination with the activity of specific molecular motors like myosin. While studies investigating the contribution of myosin activity to cell mechanics have been performed on cells attached to a substrate, we investigated mechanical properties of cells in suspension. To do this, we used multiple probes for cell mechanics including a microfluidic optical stretcher, a microfluidic microcirculation mimetic, and real-time deformability cytometry. We found that nonadherent blood cells, cells arrested in mitosis, and naturally adherent cells brought into suspension, stiffen and become more solidlike upon myosin inhibition across multiple timescales (milliseconds to minutes). Our results hold across several pharmacological and genetic perturbations targeting myosin. Our findings suggest that myosin II activity contributes to increased whole-cell compliance and fluidity. This finding is contrary to what has been reported for cells attached to a substrate, which stiffen via active myosin driven prestress. Our results establish the importance of myosin II as an active component in modulating suspended cell mechanics, with a functional role distinctly different from that for substrate-adhered cells.
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Affiliation(s)
- Chii J Chan
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Andrew E Ekpenyong
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Stefan Golfier
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Wenhong Li
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Kevin J Chalut
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Wellcome Trust/Medical Research Council Stem Cell Institute, Cambridge, United Kingdom
| | - Oliver Otto
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Jens Elgeti
- Institute of Complex Systems, Forschungszentrum Jülich, Jülich, Germany
| | - Jochen Guck
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Franziska Lautenschläger
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Department of Physics, Saarland University, Saarbrücken, Germany.
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Otto O, Rosendahl P, Mietke A, Golfier S, Herold C, Klaue D, Girardo S, Pagliara S, Ekpenyong A, Jacobi A, Wobus M, Töpfner N, Keyser UF, Mansfeld J, Fischer-Friedrich E, Guck J. Real-time deformability cytometry: on-the-fly cell mechanical phenotyping. Nat Methods 2015; 12:199-202, 4 p following 202. [DOI: 10.1038/nmeth.3281] [Citation(s) in RCA: 442] [Impact Index Per Article: 49.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 12/23/2014] [Indexed: 12/22/2022]
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12
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Otto O, Rosendahl P, Mietke A, Golfier S, Jacobi A, Töpfner N, Herold C, Klaue D, Fischer-Friedrich E, Guck J. Real-Time Deformability Cytometry: High-Throughput Mechanical Phenotyping for Changes in Cell Function. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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13
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Jost G, Golfier S, Pietsch H, Lengsfeld P, Voth M, Schmid TE, Eckardt-Schupp F, Schmid E. The influence of x-ray contrast agents in computed tomography on the induction of dicentrics and gamma-H2AX foci in lymphocytes of human blood samples. Phys Med Biol 2009; 54:6029-39. [PMID: 19779223 DOI: 10.1088/0031-9155/54/20/001] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The aim of this study was to investigate and quantify two biomarkers for radiation exposure (dicentrics and gamma-H2AX foci) in human lymphocytes after CT scans in the presence of an iodinated contrast agent. Blood samples from a healthy donor were exposed to CT scans in the absence or presence of iotrolan 300 at iodine concentrations of 5 or 50 mg ml(-1) blood. The samples were exposed to 0.025, 0.05, 0.1 and 1 Gy in a tissue equivalent body phantom. Chromosome aberration scoring and automated microscopic analysis of gamma-H2AX foci were performed in parts of the same samples. The theoretical physical dose enhancement factor (DEF) was calculated on the basis of the mass energy-absorption coefficients of iodine and blood and the photon energy spectrum of the CT tube. No significant differences in the yields of dicentrics and gamma-H2AX foci were observed in the absence or presence of 5 mg iodine ml(-1) blood up to 0.1 Gy, whereas at 1 Gy the yields were elevated for both biomarkers. At an iodine concentration of 50 mg ml(-1) serving as a positive control, a biological DEF of 9.5 +/- 1.4 and 2.3 +/- 0.5 was determined for dicentrics and gamma-H2AX foci, respectively. A physical DEF of 1.56 and 6.30 was calculated for 5 and 50 mg iodine ml(-1), respectively. Thus, it can be concluded that in the diagnostic dose range (radiation and contrast dose), no relevant biological dose-enhancing effect could be detected, whereas a clear biological dose-enhancing effect could be found for a contrast dose well outside the diagnostic CT range for the complete radiation dose range with both methods.
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Affiliation(s)
- G Jost
- Bayer Schering Pharma AG, 13353 Berlin, Germany
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14
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Klein A, Miera O, Bauer O, Golfier S, Schriever F. Chemosensitivity of B cell chronic lymphocytic leukemia and correlated expression of proteins regulating apoptosis, cell cycle and DNA repair. Leukemia 2000; 14:40-6. [PMID: 10637475 DOI: 10.1038/sj.leu.2401636] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [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: 11/08/2022]
Abstract
B cell chronic lymphocytic leukemia (B-CLL) cannot be cured with conventional chemotherapy. This clinical enigma appears to be at least partially due to the fact that B-CLL cells are resistant to programmed cell death (apoptosis) and that they are arrested in G0/G1 phase of the cell cycle. The reasons for the dysregulation of these two key cellular events in B-CLL are unclear. The present study aimed at determining correlations between the expression levels of proteins regulating apoptosis, cell cycle and DNA repair in B-CLL cells and normal B cells. In addition, the differential sensitivity of B-CLL cells to drug-induced apoptosis was quantified. We show that in B-CLL cells levels of the death-suppressor Bcl-2 correlated positively with those of the pro-apoptotic protein Bax and of the cyclin-dependent kinase (cdk) inhibitor p27Kip1. In B-CLL cells levels of the anti-apoptotic Bcl-xL showed a positive correlation with levels of the 80 kDa regulatory component (Ku80) of the DNA-dependent protein kinase that is involved in DNA double-stranded break repair. These correlations were not detected in normal B cells. The sensitivity of leukemic cells to FLUD but not to ADM, CPM or to DEX was reduced in pre-treated patients. These data support the hypothesis that in B-CLL cells death-modulators and molecules modulating cell cycle and DNA repair are regulated in a coordinated manner. Leukemia (2000) 14, 40-46.
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Affiliation(s)
- A Klein
- Department of Internal Medicine, Hematology and Oncology, Charité, Campus Virchow-Klinikum, Humboldt University, Berlin, Germany
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