1
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Sachs S, Reinhard S, Eilts J, Sauer M, Werner C. Visualizing the trans-synaptic arrangement of synaptic proteins by expansion microscopy. Front Cell Neurosci 2024; 18:1328726. [PMID: 38486709 PMCID: PMC10937466 DOI: 10.3389/fncel.2024.1328726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 02/13/2024] [Indexed: 03/17/2024] Open
Abstract
High fidelity synaptic neurotransmission in the millisecond range is provided by a defined structural arrangement of synaptic proteins. At the presynapse multi-epitope scaffolding proteins are organized spatially at release sites to guarantee optimal binding of neurotransmitters at receptor clusters. The organization of pre- and postsynaptic proteins in trans-synaptic nanocolumns would thus intuitively support efficient information transfer at the synapse. Visualization of these protein-dense regions as well as the minute size of protein-packed synaptic clefts remains, however, challenging. To enable efficient labeling of these protein complexes, we developed post-gelation immunolabeling expansion microscopy combined with Airyscan super-resolution microscopy. Using ~8-fold expanded samples, Airyscan enables multicolor fluorescence imaging with 20-40 nm spatial resolution. Post-immunolabeling of decrowded (expanded) samples provides increased labeling efficiency and allows the visualization of trans-synaptic nanocolumns. Our approach is ideally suited to investigate the pathological impact on nanocolumn arrangement e.g., in limbic encephalitis with autoantibodies targeting trans-synaptic leucine-rich glioma inactivated 1 protein (LGI1).
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Affiliation(s)
| | | | | | | | - Christian Werner
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, Würzburg, Germany
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2
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Laine RF, Heil HS, Coelho S, Nixon-Abell J, Jimenez A, Wiesner T, Martínez D, Galgani T, Régnier L, Stubb A, Follain G, Webster S, Goyette J, Dauphin A, Salles A, Culley S, Jacquemet G, Hajj B, Leterrier C, Henriques R. High-fidelity 3D live-cell nanoscopy through data-driven enhanced super-resolution radial fluctuation. Nat Methods 2023; 20:1949-1956. [PMID: 37957430 PMCID: PMC10703683 DOI: 10.1038/s41592-023-02057-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 09/29/2023] [Indexed: 11/15/2023]
Abstract
Live-cell super-resolution microscopy enables the imaging of biological structure dynamics below the diffraction limit. Here we present enhanced super-resolution radial fluctuations (eSRRF), substantially improving image fidelity and resolution compared to the original SRRF method. eSRRF incorporates automated parameter optimization based on the data itself, giving insight into the trade-off between resolution and fidelity. We demonstrate eSRRF across a range of imaging modalities and biological systems. Notably, we extend eSRRF to three dimensions by combining it with multifocus microscopy. This realizes live-cell volumetric super-resolution imaging with an acquisition speed of ~1 volume per second. eSRRF provides an accessible super-resolution approach, maximizing information extraction across varied experimental conditions while minimizing artifacts. Its optimal parameter prediction strategy is generalizable, moving toward unbiased and optimized analyses in super-resolution microscopy.
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Affiliation(s)
- Romain F Laine
- Laboratory for Molecular Cell Biology, University College London, London, UK
- The Francis Crick Institute, London, UK
- Micrographia Bio, Translation and Innovation Hub, London, UK
| | - Hannah S Heil
- Optical Cell Biology, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Simao Coelho
- Optical Cell Biology, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Jonathon Nixon-Abell
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Cambridge Institute for Medical Research, Cambridge Univeristy, Cambridge, UK
| | - Angélique Jimenez
- Aix-Marseille Université, CNRS, INP UMR7051, NeuroCyto, Marseille, France
| | - Theresa Wiesner
- Aix-Marseille Université, CNRS, INP UMR7051, NeuroCyto, Marseille, France
| | - Damián Martínez
- Optical Cell Biology, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Tommaso Galgani
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Paris, France
- Revvity Signals, Tres Cantos, Madrid, Spain
| | - Louise Régnier
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Paris, France
| | - Aki Stubb
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Department of Cell and Tissue Dynamics, Max Planck Institute for Molecular Biomedicine, Munster, Germany
| | - Gautier Follain
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, Turku, Finland
| | - Samantha Webster
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Jesse Goyette
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Aurelien Dauphin
- Unite Genetique et Biologie du Développement U934, PICT-IBiSA, Institut Curie, INSERM, CNRS, PSL Research University, Paris, France
| | - Audrey Salles
- Institut Pasteur, Université Paris Cité, Unit of Technology and Service Photonic BioImaging (UTechS PBI), C2RT, Paris, France
| | - Siân Culley
- Laboratory for Molecular Cell Biology, University College London, London, UK
- Randall Centre for Cell and Molecular Biophysics, King's College London, Guy's Campus, London, UK
| | - Guillaume Jacquemet
- Turku Bioscience Centre, University of Turku and Åbo Akademi University, Turku, Finland
- Faculty of Science and Engineering, Cell Biology, Åbo Akademi University, Turku, Finland
- Turku Bioimaging, University of Turku and Åbo Akademi University, Turku, Finland
- InFLAMES Research Flagship Center, Åbo Akademi University, Turku, Finland
| | - Bassam Hajj
- Laboratoire Physico-Chimie Curie, Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR168, Paris, France.
| | | | - Ricardo Henriques
- Laboratory for Molecular Cell Biology, University College London, London, UK.
- The Francis Crick Institute, London, UK.
- Optical Cell Biology, Instituto Gulbenkian de Ciência, Oeiras, Portugal.
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3
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Alva A, Brito-Alarcón E, Linares A, Torres-García E, Hernández HO, Pinto-Cámara R, Martínez D, Hernández-Herrera P, D'Antuono R, Wood C, Guerrero A. Fluorescence fluctuation based super resolution microscopy, basic concepts for an easy start. J Microsc 2022; 288:218-241. [PMID: 35896096 PMCID: PMC10087389 DOI: 10.1111/jmi.13135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 07/15/2022] [Accepted: 07/20/2022] [Indexed: 11/27/2022]
Abstract
Due to the wave nature of light, optical microscopy has a lower-bound lateral resolution limit of approximately half of the wavelength of visible light, i.e., within the range of 200 to 350 nm. Fluorescence Fluctuation based Super Resolution Microscopy (FF-SRM) is a term used to encompass a collection of image analysis techniques which rely on the statistical processing of temporal variations of the fluorescence signal. FF-SRM aims to reduce the uncertainty of the location of fluorophores within an image, often improving spatial resolution to several tens of nanometers. FF-SRM is suitable for live-cell imaging due to its compatibility with most fluorescent probes and relatively simple instrumental and experimental requirements, which are mostly camera-based epifluorescence instruments. Each FF-SRM approach has strengths and weaknesses, which depend directly on the underlying statistical principles through which enhanced spatial resolution is achieved. In this review, the basic concepts and principles behind a range of FF-SRM methods published to date are described. Their operational parameters are explained and guidance for its selection is provided. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Alma Alva
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Eduardo Brito-Alarcón
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Alejandro Linares
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Esley Torres-García
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.,Centro de Investigación en Ciencias, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Haydee O Hernández
- Posgrado en Ciencia e Ingeniería de la Computación, Universidad Nacional Autónoma de México, México City, México
| | - Raúl Pinto-Cámara
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.,Centro de Investigación en Ciencias, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
| | - Damián Martínez
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Paul Hernández-Herrera
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Rocco D'Antuono
- Crick Advanced Light Microscopy Science and Technology Platform, The Francis Crick Institute, London, UK
| | - Christopher Wood
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Adán Guerrero
- Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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4
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Maddox AL, Brehove MS, Eliato KR, Saftics A, Romano E, Press MF, Mortimer J, Jones V, Schmolze D, Seewaldt VL, Jovanovic-Talisman T. Molecular Assessment of HER2 to Identify Signatures Associated with Therapy Response in HER2-Positive Breast Cancer. Cancers (Basel) 2022; 14:2795. [PMID: 35681773 PMCID: PMC9179327 DOI: 10.3390/cancers14112795] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 05/29/2022] [Accepted: 06/01/2022] [Indexed: 11/16/2022] Open
Abstract
Trastuzumab, the prototype HER2-directed therapy, has markedly improved survival for women with HER2-positive breast cancers. However, only 40-60% of women with HER2-positive breast cancers achieve a complete pathological response to chemotherapy combined with HER2-directed therapy. The current diagnostic assays have poor positive-predictive accuracy in identifying therapy-responsive breast cancers. Here, we deployed quantitative single molecule localization microscopy to assess the molecular features of HER2 in a therapy-responsive setting. Using fluorescently labeled trastuzumab as a probe, we first compared the molecular features of HER2 in trastuzumab-sensitive (BT-474 and SK-BR-3) and trastuzumab-resistant (BT-474R and JIMT-1) cultured cell lines. Trastuzumab-sensitive cells had significantly higher detected HER2 densities and clustering. We then evaluated HER2 in pre-treatment core biopsies from women with breast cancer undergoing neoadjuvant therapy. A complete pathological response was associated with a high detected HER2 density and significant HER2 clustering. These results established the nano-organization of HER2 as a potential signature of therapy-responsive disease.
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Affiliation(s)
- Adam L. Maddox
- Department of Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA; (A.L.M.); (M.S.B.); (K.R.E.); (A.S.); (E.R.)
| | - Matthew S. Brehove
- Department of Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA; (A.L.M.); (M.S.B.); (K.R.E.); (A.S.); (E.R.)
| | - Kiarash R. Eliato
- Department of Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA; (A.L.M.); (M.S.B.); (K.R.E.); (A.S.); (E.R.)
| | - Andras Saftics
- Department of Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA; (A.L.M.); (M.S.B.); (K.R.E.); (A.S.); (E.R.)
| | - Eugenia Romano
- Department of Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA; (A.L.M.); (M.S.B.); (K.R.E.); (A.S.); (E.R.)
| | - Michael F. Press
- Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089, USA;
| | - Joanne Mortimer
- Department of Medical Oncology, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA;
| | - Veronica Jones
- Department of Surgery, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA;
| | - Daniel Schmolze
- Department of Pathology, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA;
| | - Victoria L. Seewaldt
- Department of Population Sciences, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA;
| | - Tijana Jovanovic-Talisman
- Department of Molecular Medicine, Beckman Research Institute, City of Hope Comprehensive Cancer Center, Duarte, CA 91010, USA; (A.L.M.); (M.S.B.); (K.R.E.); (A.S.); (E.R.)
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5
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Yao L, Zhang L, Chen L, Gong X, Zhong J, Wang B, Fei Y, Mi L, Ma J. Dynamic Structure of Yeast Septin by Fast Fluctuation-Enhanced Structured Illumination Microscopy. Microorganisms 2021; 9:microorganisms9112255. [PMID: 34835381 PMCID: PMC8620077 DOI: 10.3390/microorganisms9112255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/23/2021] [Accepted: 10/25/2021] [Indexed: 12/05/2022] Open
Abstract
When Saccharomyces cerevisiae divides, a structure composed of different septin proteins arranged according to a certain rule is formed at the cell division site. The structure undergoes multiple remodeling stages during the cell cycle, thus guiding the yeast cells to complete the entire division process. Although the higher-order structure of septins can be determined using electron microscopy, the septin’s dynamic processes are poorly understood because of limitations in living cell super-resolution imaging technology. Herein, we describe a high lateral resolution and temporal resolution technique, known as fast fluctuation-enhanced structured illumination microscopy (fFE-SIM), which more than doubles the SIM resolution at a frame rate of 38 Hz in living cells. This allows a highly dynamic and sparse septin structure to be observed in Saccharomyces cerevisiae.
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Affiliation(s)
- Longfang Yao
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, School of Information Science and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; (L.Y.); (L.C.); (X.G.); (Y.F.)
| | - Li Zhang
- Shanghai Engineering Research Center of Industrial Microorganisms, The Multiscale Research Institute of Complex Systems (MRICS), School of Life Sciences, Fudan University, 220 Handan Road, Shanghai 200433, China;
| | - Liwen Chen
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, School of Information Science and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; (L.Y.); (L.C.); (X.G.); (Y.F.)
| | - Xingyu Gong
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, School of Information Science and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; (L.Y.); (L.C.); (X.G.); (Y.F.)
| | - Jiahui Zhong
- Institute of Biomedical Engineering and Technology, Academy for Engineer and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China;
| | - Baoju Wang
- Centre for Optical and Electromagnetic Research, Guangdong Provincial Key Laboratory of Optical Information Materials and Technology, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou 510006, China;
| | - Yiyan Fei
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, School of Information Science and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; (L.Y.); (L.C.); (X.G.); (Y.F.)
| | - Lan Mi
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, School of Information Science and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; (L.Y.); (L.C.); (X.G.); (Y.F.)
- Institute of Biomedical Engineering and Technology, Academy for Engineer and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China;
- Correspondence: (L.M.); (J.M.)
| | - Jiong Ma
- Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Optical Science and Engineering, School of Information Science and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China; (L.Y.); (L.C.); (X.G.); (Y.F.)
- Shanghai Engineering Research Center of Industrial Microorganisms, The Multiscale Research Institute of Complex Systems (MRICS), School of Life Sciences, Fudan University, 220 Handan Road, Shanghai 200433, China;
- Institute of Biomedical Engineering and Technology, Academy for Engineer and Technology, Fudan University, 220 Handan Road, Shanghai 200433, China;
- Correspondence: (L.M.); (J.M.)
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6
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Yao L, Zhang L, Fei Y, Chen L, Mi L, Ma J. Application of SNAP-Tag in Expansion Super-Resolution Microscopy Using DNA Oligostrands. Front Chem 2021; 9:640519. [PMID: 33996746 PMCID: PMC8119759 DOI: 10.3389/fchem.2021.640519] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/12/2021] [Indexed: 11/13/2022] Open
Abstract
Expansion super-resolution technology is a new technology developed in recent years. It anchors the dye on the hydrogel and the dye expands with the expansion of the hydrogel so that a super-resolution map can be obtained under an ordinary microscope. However, by labeling the target protein with a first antibody and secondary antibody, the distance between the fluorescent group and the actual target protein is greatly increased. Although fluorescent proteins can also be used for expansion super-resolution to reduce this effect, the fluorescent protein is often destroyed during sample preparation. To solve this problem, we developed a novel label system for expansion microscopy, based on a DNA oligostrand linked with a fluorescent dye, acrylamide group (linker), and benzoylguanine (BG, a small substrate molecule for SNAP-tag). This protocol greatly reduced the error between the position of fluorescent group and the actual target protein, and also reduced loss of the fluorescent group during sample preparation.
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Affiliation(s)
- Longfang Yao
- Department of Optical Science and Engineering, Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Fudan University, Shanghai, China
| | - Li Zhang
- Shanghai Engineering Research Center of Industrial Microorganisms, The Multiscale Research Institute of Complex Systems, School of Life Sciences, Fudan University, Shanghai, China
| | - Yiyan Fei
- Department of Optical Science and Engineering, Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Fudan University, Shanghai, China
| | - Liwen Chen
- Department of Optical Science and Engineering, Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Fudan University, Shanghai, China
| | - Lan Mi
- Department of Optical Science and Engineering, Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Fudan University, Shanghai, China
| | - Jiong Ma
- Department of Optical Science and Engineering, Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Green Photoelectron Platform, Fudan University, Shanghai, China.,Shanghai Engineering Research Center of Industrial Microorganisms, The Multiscale Research Institute of Complex Systems, School of Life Sciences, Fudan University, Shanghai, China.,Insititute of Biomedical Engineering and Technology, Academy for Engineering and Technology, Fudan University, Shanghai, China
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7
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Rossman U, Dadosh T, Eldar YC, Oron D. cSPARCOM: Multi-detector reconstruction by confocal super-resolution correlation microscopy. OPTICS EXPRESS 2021; 29:12772-12786. [PMID: 33985027 DOI: 10.1364/oe.418422] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/26/2021] [Indexed: 06/12/2023]
Abstract
Image scanning microscopy (ISM), an upgraded successor of the ubiquitous confocal microscope, facilitates up to two-fold improvement in lateral resolution, and has become an indispensable element in the toolbox of the bio-imaging community. Recently, super-resolution optical fluctuation image scanning microscopy (SOFISM) integrated the analysis of intensity-fluctuations information into the basic ISM architecture, to enhance its resolving power. Both of these techniques typically rely on pixel-reassignment as a fundamental processing step, in which the parallax of different detector elements to the sample is compensated by laterally shifting the point spread function (PSF). Here, we propose an alternative analysis approach, based on the recent high-performing sparsity-based super-resolution correlation microscopy (SPARCOM) method. Through measurements of DNA origami nano-rulers and fixed cells labeled with organic dye, we experimentally show that confocal SPARCOM (cSPARCOM), which circumvents pixel-reassignment altogether, provides enhanced resolution compared to pixel-reassigned based analysis. Thus, cSPARCOM further promotes the effectiveness of ISM, and particularly that of correlation based ISM implementations such as SOFISM, where the PSF deviates significantly from spatial invariance.
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8
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Kubalová I, Schmidt Černohorská M, Huranová M, Weisshart K, Houben A, Schubert V. A protocol to expand plant nuclei. Methods Cell Biol 2020; 161:197-216. [PMID: 33478690 DOI: 10.1016/bs.mcb.2020.06.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The resolution achieved by conventional light microscopy is limited by light diffraction. This obstacle can be overcome either by optical super-resolution techniques or by the recently developed method to physically expand specimens, called expansion microscopy (ExM). The method utilizes polymer chemistry and the ability of a swellable polyelectrolyte hydrogel to absorb water, and thus to expand its size. The procedure was successfully applied to different species and tissue samples, mostly from the animal kingdom. Physically expanded nuclei and chromosomes in combination with specific protein labeling and super-resolution microscopy may provide new insight into the ultrastructure, dynamics, and function of plant chromatin. Here we provide a detailed protocol to expand isolated plant nuclei and visualize proteins by indirect immunolabeling. With the focus on chromatin structure, we expanded isolated barley nuclei from root tips and visualized the centromere-specific histone H3 variant CENH3. The achieved physical expansion of ~4.2 times allowed the detection of DAPI-labeled chromatin structures already by conventional wild-field (WF) microscopy with a maximal resolution of ~50-60nm. By applying structured illumination microscopy (SIM), doubling the WF resolution, chromatin structures at a resolution of ~25-35nm were observed. However, a certain distortion of the centromeric chromatin ultrastructure became obvious.
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Affiliation(s)
- Ivona Kubalová
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany
| | - Markéta Schmidt Černohorská
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martina Huranová
- Laboratory of Adaptive Immunity, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | | | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany.
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