1
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Pepe A, Groen J, Zurzolo C, Sartori-Rupp A. Correlative cryo-microscopy pipelines for in situ cellular studies. Methods Cell Biol 2024; 187:175-203. [PMID: 38705624 DOI: 10.1016/bs.mcb.2024.02.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
Correlative cryo-microscopy pipelines combining light and electron microscopy and tomography in cryogenic conditions (cryoCLEM) on the same sample are powerful methods for investigating the structure of specific cellular targets identified by a fluorescent tag within their unperturbed cellular environment. CryoCLEM approaches circumvent one of the inherent limitations of cryo EM, and specifically cryo electron tomography (cryoET), of identifying the imaged structures in the crowded 3D environment of cells. Whereas several cryoCLEM approaches are based on thinning the sample by cryo FIB milling, here we present detailed protocols of two alternative cryoCLEM approaches for in situ studies of adherent cells at the single-cell level without the need for such cryo-thinning. The first approach is a complete cryogenic pipeline in which both fluorescence and electronic imaging are performed on frozen-hydrated samples, the second is a hybrid cryoCLEM approach in which fluorescence imaging is performed at room temperature, followed by rapid freezing and subsequent cryoEM imaging. We provide a detailed description of the two methods we have employed for imaging fluorescently labeled cellular structures with thickness below 350-500nm, such as cell protrusions and organelles located in the peripheral areas of the cells.
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Affiliation(s)
- Anna Pepe
- Membrane Traffic and Pathogenesis, Institut Pasteur, Paris, France
| | - Johannes Groen
- NanoImaging Core Facility, Institut Pasteur, Paris, France; Dynamics of Host-Pathogen Interactions, Institut Pasteur, Paris, France
| | - Chiara Zurzolo
- Membrane Traffic and Pathogenesis, Institut Pasteur, Paris, France
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2
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Engel L, Zaoralová M, Zhou M, Dunn AR, Oliver SL. Extracellular filaments revealed by affinity capture cryo-electron tomography of lymphocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.05.552110. [PMID: 37577490 PMCID: PMC10418515 DOI: 10.1101/2023.08.05.552110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Cryogenic-electron tomography (cryo-ET) has provided an un-precedented glimpse into the nanoscale architecture of cells by combining cryogenic preservation of biological structures with electron tomography. Micropatterning of extracellular matrix proteins is increasingly used as a method to prepare adherent cell types for cryo-ET as it promotes optimal positioning of cells and subcellular regions of interest for vitrification, cryo-focused ion beam (cryo-FIB) milling, and data acquisition. Here we demonstrate a micropatterning workflow for capturing minimally adherent cell types, human T-cells and Jurkat cells, for cryo-FIB and cryo-ET. Our affinity capture system facilitated the nanoscale imaging of Jurkat cells, revealing extracellular filamentous structures. It improved workflow efficiency by consistently producing grids with a sufficient number of well-positioned cells for an entire cryo-FIB session. Affinity capture can be extended to facilitate high resolution imaging of other adherent and non-adherent cell types with cryo-ET.
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3
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Zimmermann L, Chlanda P. Cryo-electron tomography of viral infection - from applications to biosafety. Curr Opin Virol 2023; 61:101338. [PMID: 37348443 DOI: 10.1016/j.coviro.2023.101338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 04/25/2023] [Accepted: 05/28/2023] [Indexed: 06/24/2023]
Abstract
Cellular cryo-electron tomography (cryo-ET) offers 3D snapshots at molecular resolution capturing pivotal steps during viral infection. However, tomogram quality depends on the vitrification level of the sample and its thickness. In addition, mandatory inactivation protocols to assure biosafety when handling highly pathogenic viruses during cryo-ET can compromise sample preservation. Here, we focus on different strategies applied in cryo-ET and discuss their advantages and limitations with reference to severe acute respiratory syndrome coronavirus 2 studies. We highlight the importance of virus-like particle (VLP) and replicon systems to study virus assembly and replication in a cellular context without inactivation protocols. We discuss the application of chemical fixation and different irradiation methods in cryo-ET sample preparation and acquisition workflows.
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Affiliation(s)
- Liv Zimmermann
- Schaller Research Groups, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany
| | - Petr Chlanda
- Schaller Research Groups, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany.
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4
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Rickard BP, Overchuk M, Chappell VA, Kemal Ruhi M, Sinawang PD, Nguyen Hoang TT, Akin D, Demirci U, Franco W, Fenton SE, Santos JH, Rizvi I. Methods to Evaluate Changes in Mitochondrial Structure and Function in Cancer. Cancers (Basel) 2023; 15:2564. [PMID: 37174030 PMCID: PMC10177605 DOI: 10.3390/cancers15092564] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 05/15/2023] Open
Abstract
Mitochondria are regulators of key cellular processes, including energy production and redox homeostasis. Mitochondrial dysfunction is associated with various human diseases, including cancer. Importantly, both structural and functional changes can alter mitochondrial function. Morphologic and quantifiable changes in mitochondria can affect their function and contribute to disease. Structural mitochondrial changes include alterations in cristae morphology, mitochondrial DNA integrity and quantity, and dynamics, such as fission and fusion. Functional parameters related to mitochondrial biology include the production of reactive oxygen species, bioenergetic capacity, calcium retention, and membrane potential. Although these parameters can occur independently of one another, changes in mitochondrial structure and function are often interrelated. Thus, evaluating changes in both mitochondrial structure and function is crucial to understanding the molecular events involved in disease onset and progression. This review focuses on the relationship between alterations in mitochondrial structure and function and cancer, with a particular emphasis on gynecologic malignancies. Selecting methods with tractable parameters may be critical to identifying and targeting mitochondria-related therapeutic options. Methods to measure changes in mitochondrial structure and function, with the associated benefits and limitations, are summarized.
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Affiliation(s)
- Brittany P. Rickard
- Curriculum in Toxicology & Environmental Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Marta Overchuk
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, and North Carolina State University, Raleigh, NC 27695, USA
| | - Vesna A. Chappell
- Mechanistic Toxicology Branch, Division of Translational Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Mustafa Kemal Ruhi
- Institute of Biomedical Engineering, Boğaziçi University, Istanbul 34684, Turkey
| | - Prima Dewi Sinawang
- Canary Center at Stanford for Cancer Early Detection, Department of Radiology, School of Medicine, Palo Alto, CA 94304, USA
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Tina Thuy Nguyen Hoang
- Department of Biomedical Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Demir Akin
- Canary Center at Stanford for Cancer Early Detection, Department of Radiology, School of Medicine, Palo Alto, CA 94304, USA
- Center for Cancer Nanotechnology Excellence for Translational Diagnostics (CCNE-TD), School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Utkan Demirci
- Canary Center at Stanford for Cancer Early Detection, Department of Radiology, School of Medicine, Palo Alto, CA 94304, USA
| | - Walfre Franco
- Department of Biomedical Engineering, University of Massachusetts Lowell, Lowell, MA 01854, USA
| | - Suzanne E. Fenton
- Mechanistic Toxicology Branch, Division of Translational Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Janine H. Santos
- Mechanistic Toxicology Branch, Division of Translational Toxicology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Imran Rizvi
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, and North Carolina State University, Raleigh, NC 27695, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
- Center for Environmental Health and Susceptibility, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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5
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Zeng X, Kahng A, Xue L, Mahamid J, Chang YW, Xu M. High-throughput cryo-ET structural pattern mining by unsupervised deep iterative subtomogram clustering. Proc Natl Acad Sci U S A 2023; 120:e2213149120. [PMID: 37027429 PMCID: PMC10104553 DOI: 10.1073/pnas.2213149120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 02/24/2023] [Indexed: 04/08/2023] Open
Abstract
Cryoelectron tomography directly visualizes heterogeneous macromolecular structures in their native and complex cellular environments. However, existing computer-assisted structure sorting approaches are low throughput or inherently limited due to their dependency on available templates and manual labels. Here, we introduce a high-throughput template-and-label-free deep learning approach, Deep Iterative Subtomogram Clustering Approach (DISCA), that automatically detects subsets of homogeneous structures by learning and modeling 3D structural features and their distributions. Evaluation on five experimental cryo-ET datasets shows that an unsupervised deep learning based method can detect diverse structures with a wide range of molecular sizes. This unsupervised detection paves the way for systematic unbiased recognition of macromolecular complexes in situ.
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Affiliation(s)
- Xiangrui Zeng
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA15213
| | - Anson Kahng
- Computer Science Department, University of Rochester, Rochester, NY14620
| | - Liang Xue
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg69117, Germany
- Faculty of Biosciences, Collaboration for joint PhD degree between European Molecular Biology Laboratory and Heidelberg University, Heidelberg69117, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg69117, Germany
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104
| | - Min Xu
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA15213
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6
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Electron tomography unravels new insights into fiber cell wall nanostructure; exploring 3D macromolecular biopolymeric nano-architecture of spruce fiber secondary walls. Sci Rep 2023; 13:2350. [PMID: 36759530 PMCID: PMC9911387 DOI: 10.1038/s41598-023-29113-x] [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: 12/01/2022] [Accepted: 01/31/2023] [Indexed: 02/11/2023] Open
Abstract
Lignocellulose biomass has a tremendous potential as renewable biomaterials for fostering the "bio-based society" and circular bioeconomy paradigm. It requires efficient use and breakdown of fiber cell walls containing mainly cellulose, hemicellulose and lignin biopolymers. Despite their great importance, there is an extensive debate on the true structure of fiber walls and knowledge on the macromolecular nano-organization is limited and remains elusive in 3D. We employed dual-axis electron tomography that allows visualization of previously unseen 3D macromolecular organization/biopolymeric nano-architecture of the secondary S2 layer of Norway spruce fiber wall. Unprecedented 3D nano-structural details with novel insights into cellulose microfibrils (~ 2 nm diameter), macrofibrils, nano-pore network and cell wall chemistry (volume %) across the S2 were explored and quantified including simulation of structure related permeability. Matrix polymer association with cellulose varied between microfibrils and macrofibrils with lignin directly associated with MFs. Simulated bio-nano-mechanical properties revealed stress distribution within the S2 and showed similar properties between the idealized 3D model and the native S2 (actual tomogram). Present work has great potential for significant advancements in lignocellulose research on nano-scale understanding of cell wall assembly/disassembly processes leading to more efficient industrial processes of functionalization, valorization and target modification technologies.
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7
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Proteomic mapping and optogenetic manipulation of membrane contact sites. Biochem J 2022; 479:1857-1875. [PMID: 36111979 PMCID: PMC9555801 DOI: 10.1042/bcj20220382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/17/2022]
Abstract
Membrane contact sites (MCSs) mediate crucial physiological processes in eukaryotic cells, including ion signaling, lipid metabolism, and autophagy. Dysregulation of MCSs is closely related to various diseases, such as type 2 diabetes mellitus (T2DM), neurodegenerative diseases, and cancers. Visualization, proteomic mapping and manipulation of MCSs may help the dissection of the physiology and pathology MCSs. Recent technical advances have enabled better understanding of the dynamics and functions of MCSs. Here we present a summary of currently known functions of MCSs, with a focus on optical approaches to visualize and manipulate MCSs, as well as proteomic mapping within MCSs.
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8
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Gupta T, He X, Uddin MR, Zeng X, Zhou A, Zhang J, Freyberg Z, Xu M. Self-supervised learning for macromolecular structure classification based on cryo-electron tomograms. Front Physiol 2022; 13:957484. [PMID: 36111160 PMCID: PMC9468634 DOI: 10.3389/fphys.2022.957484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 08/02/2022] [Indexed: 11/21/2022] Open
Abstract
Macromolecular structure classification from cryo-electron tomography (cryo-ET) data is important for understanding macro-molecular dynamics. It has a wide range of applications and is essential in enhancing our knowledge of the sub-cellular environment. However, a major limitation has been insufficient labelled cryo-ET data. In this work, we use Contrastive Self-supervised Learning (CSSL) to improve the previous approaches for macromolecular structure classification from cryo-ET data with limited labels. We first pretrain an encoder with unlabelled data using CSSL and then fine-tune the pretrained weights on the downstream classification task. To this end, we design a cryo-ET domain-specific data-augmentation pipeline. The benefit of augmenting cryo-ET datasets is most prominent when the original dataset is limited in size. Overall, extensive experiments performed on real and simulated cryo-ET data in the semi-supervised learning setting demonstrate the effectiveness of our approach in macromolecular labeling and classification.
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Affiliation(s)
- Tarun Gupta
- Department of Computer Science and Engineering, Indian Institute of Technology, Indore, India
| | - Xuehai He
- Department of Electrical and Computer Engineering, University of California, San Diego, San Diego, CA, United States
| | - Mostofa Rafid Uddin
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Xiangrui Zeng
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA, United States
| | - Andrew Zhou
- Irvington High School, Irvington, NY, United States
| | - Jing Zhang
- Department of Computer Science, University of California, Irvine, Irvine, CA, United States
| | - Zachary Freyberg
- Departments of Psychiatry and Cell Biology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Min Xu
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA, United States
- *Correspondence: Min Xu,
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9
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Abstract
The three-dimensional organization of biomolecules important for the functioning of all living systems can be determined by cryo-electron tomography imaging under native biological contexts. Cryo-electron tomography is continually expanding and evolving, and the development of new methods that use the latest technology for sample thinning is enabling the visualization of ever larger and more complex biological systems, allowing imaging across scales. Quantitative cryo-electron tomography possesses the capability of visualizing the impact of molecular and environmental perturbations in subcellular structure and function to understand fundamental biological processes. This review provides an overview of current hardware and software developments that allow quantitative cryo-electron tomography studies and their limitations and how overcoming them may allow us to unleash the full power of cryo-electron tomography.
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Affiliation(s)
- Paula P Navarro
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, United States.,Department of Genetics, Harvard Medical School, Boston, MA, United States
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10
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Three-dimensional SEM, TEM, and STEM for analysis of large-scale biological systems. Histochem Cell Biol 2022; 158:203-211. [PMID: 35829815 PMCID: PMC9399040 DOI: 10.1007/s00418-022-02117-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2022] [Indexed: 12/12/2022]
Abstract
A major aim in structural cell biology is to analyze intact cells in three dimensions, visualize subcellular structures, and even localize proteins at the best possible resolution in three dimensions. Though recently developed electron microscopy tools such as electron tomography, or three-dimensional (3D) scanning electron microscopy, offer great resolution in three dimensions, the challenge is that, the better the resolution, usually the smaller the volume under investigation. Several different approaches to overcome this challenge were presented at the Microscopy Conference in Vienna in 2021. These tools include array tomography, batch tomography, or scanning transmission electron tomography, all of which can nowadays be extended toward correlative light and electron tomography, with greatly increased 3D information. Here, we review these tools, describe the underlying procedures, and discuss their advantages and limits.
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11
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Dickerson JL, Lu PH, Hristov D, Dunin-Borkowski RE, Russo CJ. Imaging biological macromolecules in thick specimens: The role of inelastic scattering in cryoEM. Ultramicroscopy 2022; 237:113510. [PMID: 35367900 PMCID: PMC9355893 DOI: 10.1016/j.ultramic.2022.113510] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/24/2022] [Accepted: 03/06/2022] [Indexed: 11/17/2022]
Abstract
We investigate potential improvements in using electron cryomicroscopy to image thick specimens with high-resolution phase contrast imaging. In particular, using model experiments, electron scattering theory, Monte Carlo and multislice simulations, we determine the potential for improving electron cryomicrographs of proteins within a cell using chromatic aberration (Cc) correction. We show that inelastically scattered electrons lose a quantifiable amount of spatial coherence as they transit the specimen, yet can be used to enhance the signal from thick biological specimens (in the 1000 to 5000 Å range) provided they are imaged close to focus with an achromatic lens. This loss of information quantified here, which we call "specimen induced decoherence", is a fundamental limit on imaging biological molecules in situ. We further show that with foreseeable advances in transmission electron microscope technology, it should be possible to directly locate and uniquely identify sub-100 kDa proteins without the need for labels, in a vitrified specimen taken from a cell.
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Affiliation(s)
- Joshua L Dickerson
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Peng-Han Lu
- Ernst Ruska-Centrum für Mikroskopie und Spektroskopie mit Elektronen, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Dilyan Hristov
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centrum für Mikroskopie und Spektroskopie mit Elektronen, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Christopher J Russo
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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12
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Parlanti P, Cappello V. Microscopes, tools, probes, and protocols: A guide in the route of correlative microscopy for biomedical investigation. Micron 2021; 152:103182. [PMID: 34801960 DOI: 10.1016/j.micron.2021.103182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 11/12/2021] [Accepted: 11/14/2021] [Indexed: 12/11/2022]
Abstract
In the last decades, the advancements of microscopes technology, together with the development of new imaging approaches, are trying to address some biological questions that have been unresolved in the past: the need to combine in the same analysis temporal, functional and morphological information on the biological sample has become pressing. For this reason, the use of correlative microscopy, in which two or more imaging techniques are combined in the same analysis, is getting increasingly widespread. In fact, correlative microscopy can overcome limitations of a single imaging method, giving access to a larger amount of information from the same specimen. However, correlative microscopy can be challenging, and appropriate protocols for sample preparation and imaging methods must be selected. Here we review the state of the art of correlating electron microscopy with different imaging methods, focusing on sample preparation, tools, and labeling methods, with the aim to provide a comprehensive guide for those scientists who are approaching the field of correlative methods.
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Affiliation(s)
- Paola Parlanti
- Istituto Italiano di Tecnologia, Center for Materials Interfaces, Electron Crystallography, Viale Rinaldo Piaggio 34, I-56025, Pontedera (PI), Italy.
| | - Valentina Cappello
- Istituto Italiano di Tecnologia, Center for Materials Interfaces, Electron Crystallography, Viale Rinaldo Piaggio 34, I-56025, Pontedera (PI), Italy.
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13
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Abstract
Cryo-electron tomography has stepped fully into the spotlight. Enthusiasm is high. Fortunately for us, this is an exciting time to be a cryotomographer, but there is still a way to go before declaring victory. Despite its potential, cryo-electron tomography possesses many inherent challenges. How do we image through thick cell samples, and possibly even tissue? How do we identify a protein of interest amidst the noisy, crowded environment of the cytoplasm? How do we target specific moments of a dynamic cellular process for tomographic imaging? In this review, we cover the history of cryo-electron tomography and how it came to be, roughly speaking, as well as the many approaches that have been developed to overcome its intrinsic limitations.
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Affiliation(s)
- Ryan K. Hylton
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Matthew T. Swulius
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
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14
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Engel L, Vasquez CG, Montabana EA, Sow BM, Walkiewicz MP, Weis WI, Dunn AR. Lattice micropatterning for cryo-electron tomography studies of cell-cell contacts. J Struct Biol 2021; 213:107791. [PMID: 34520869 DOI: 10.1016/j.jsb.2021.107791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/14/2021] [Accepted: 08/28/2021] [Indexed: 01/24/2023]
Abstract
Cryo-electron tomography is the highest resolution tool available for structural analysis of macromolecular complexes within their native cellular environments. At present, data acquisition suffers from low throughput, in part due to the low probability of positioning a cell such that the subcellular structure of interest is on a region of the electron microscopy (EM) grid that is suitable for imaging. Here, we photo-micropatterned EM grids to optimally position endothelial cells so as to enable high-throughput imaging of cell-cell contacts. Lattice micropatterned grids increased the average distance between intercellular contacts and thicker cell nuclei such that the regions of interest were sufficiently thin for direct imaging. We observed a diverse array of membranous and cytoskeletal structures at intercellular contacts, demonstrating the utility of this technique in enhancing the rate of data acquisition for cellular cryo-electron tomography studies.
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Affiliation(s)
- Leeya Engel
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States
| | - Claudia G Vasquez
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States
| | | | - Belle M Sow
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States
| | - Marcin P Walkiewicz
- Cell Sciences Imaging Facility, Stanford University, Stanford, CA 94305, United States
| | - William I Weis
- Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, United States; Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Alexander R Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, United States.
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15
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Ortega E, Boothroyd C, de Jonge N. The influence of chromatic aberration on the dose-limited spatial resolution of transmission electron microscopy. Ultramicroscopy 2021; 230:113383. [PMID: 34450389 DOI: 10.1016/j.ultramic.2021.113383] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 08/11/2021] [Accepted: 08/15/2021] [Indexed: 11/15/2022]
Abstract
The effect of chromatic aberration (CC) on the spatial resolution in transmission electron microscopy (TEM) was studied in thick specimens in which the sample becomes the limiting factor in the resolution. The sample influences the energy spread of the electron beam, allows only a limited electron dose, and modulates electron scattering events. The experimental set-up consisted of a thin silicon nitride membrane and a silicon wedge containing gold nanoparticles. The resolution was measured as a function of electron dose and sample thickness for different sample configurations and for different microscopy modalities including regular TEM, energy filtered TEM (EFTEM) and CC-corrected TEM. Comparison with an analytical model aided the understanding of the experimental data applied over varied conditions. The general trend for all microscopy modalities was a transition from a noise-limited resolution at low electron dose to a CC-limited resolution at high-dose in the absence of beam blurring. EFTEM required an accurate energy slit offset and an optimal energy spread to energy-slit width ratio to surpass regular TEM. The key advantage of CC correction appeared to be the best possible resolution for larger sample thickness at low electron dose outperforming EFTEM by about fifty percent. Several hypothetical sample configurations relevant to liquid phase electron microscopy were evaluated as well to demonstrate the capabilities of the analytical model and to determine the most optimal microscopy modality for this type of experiment. The analytical model included an automated optimization of the EFTEM settings and may aid in optimizing the sample-limited resolution for experimental analysis and planning.
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Affiliation(s)
- Eduardo Ortega
- INM-Leibniz Institute for New Materials, Saarbrücken 66123, Germany
| | - Chris Boothroyd
- Facility for Analysis Characterisation Testing and Simulation and School of Materials Science and Engineering, Nanyang Technological University, 639798 Singapore
| | - Niels de Jonge
- INM-Leibniz Institute for New Materials, Saarbrücken 66123, Germany; Department of Physics, Saarland University, Saarbrücken 66123, Germany.
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16
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Baena V, Conrad R, Friday P, Fitzgerald E, Kim T, Bernbaum J, Berensmann H, Harned A, Nagashima K, Narayan K. FIB-SEM as a Volume Electron Microscopy Approach to Study Cellular Architectures in SARS-CoV-2 and Other Viral Infections: A Practical Primer for a Virologist. Viruses 2021; 13:v13040611. [PMID: 33918371 PMCID: PMC8066521 DOI: 10.3390/v13040611] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 01/06/2023] Open
Abstract
The visualization of cellular ultrastructure over a wide range of volumes is becoming possible by increasingly powerful techniques grouped under the rubric “volume electron microscopy” or volume EM (vEM). Focused ion beam scanning electron microscopy (FIB-SEM) occupies a “Goldilocks zone” in vEM: iterative and automated cycles of milling and imaging allow the interrogation of microns-thick specimens in 3-D at resolutions of tens of nanometers or less. This bestows on FIB-SEM the unique ability to aid the accurate and precise study of architectures of virus-cell interactions. Here we give the virologist or cell biologist a primer on FIB-SEM imaging in the context of vEM and discuss practical aspects of a room temperature FIB-SEM experiment. In an in vitro study of SARS-CoV-2 infection, we show that accurate quantitation of viral densities and surface curvatures enabled by FIB-SEM imaging reveals SARS-CoV-2 viruses preferentially located at areas of plasma membrane that have positive mean curvatures.
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Affiliation(s)
- Valentina Baena
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Ryan Conrad
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Patrick Friday
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Ella Fitzgerald
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Taeeun Kim
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - John Bernbaum
- National Institute of Allergy and Infectious Diseases, Division of Clinical Research, Integrated Research Facility at Fort Detrick (IRF-Frederick), Frederick, MD 21702, USA;
| | - Heather Berensmann
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Adam Harned
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Kunio Nagashima
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Kedar Narayan
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA; (V.B.); (R.C.); (P.F.); (E.F.); (T.K.); (H.B.); (A.H.); (K.N.)
- Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
- Correspondence:
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17
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Abstract
Since its entry into biomedical research in the first half of the twentieth century, electron microscopy has been a valuable tool for lung researchers to explore the lung's delicate ultrastructure. Among others, it proved the existence of a continuous alveolar epithelium and demonstrated the surfactant lining layer. With the establishment of serial sectioning transmission electron microscopy, as the first "volume electron microscopic" technique, electron microscopy entered the third dimension and investigations of the lung's three-dimensional ultrastructure became possible. Over the years, further techniques, ranging from electron tomography over serial block-face and focused ion beam scanning electron microscopy to array tomography became available. All techniques cover different volumes and resolutions, and, thus, different scientific questions. This review gives an overview of these techniques and their application in lung research, focusing on their fields of application and practical implementation. Furthermore, an introduction is given how the output raw data are processed and the final three-dimensional models can be generated.
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Affiliation(s)
- Jan Philipp Schneider
- Institute of Functional and Applied Anatomy, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), 30625 Hannover, Germany
| | - Jan Hegermann
- Institute of Functional and Applied Anatomy, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), 30625 Hannover, Germany
- Research Core Unit Electron Microscopy, Hannover Medical School, 30625 Hannover, Germany
| | - Christoph Wrede
- Institute of Functional and Applied Anatomy, Hannover Medical School, 30625 Hannover, Germany
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), 30625 Hannover, Germany
- Research Core Unit Electron Microscopy, Hannover Medical School, 30625 Hannover, Germany
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18
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Hylton RK, Seader VH, Swulius MT. Cryo-Electron Tomography and Automatic Segmentation of Cultured Hippocampal Neurons. Methods Mol Biol 2021; 2215:25-48. [PMID: 33367998 DOI: 10.1007/978-1-0716-0966-8_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cryo-electron tomography is fast becoming a preferred method for studying intracellular environments at the molecular scale. Increases in data collection throughput means that large numbers of tomograms can be generated at rates too fast for humans to easily explore quantitatively. Currently, there is a large effort to make data collection and segmentation tools more automated. Here, we describe a workflow for preparing cultured neurons on electron microscopy grids, batch tomographic data collection, reconstruction and automatic segmentation using freely and commercially available software.
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Affiliation(s)
- Ryan K Hylton
- Department of Biochemistry and Molecular Biology, The Penn State College of Medicine, Hershey, PA, USA
| | - Victoria H Seader
- Department of Biochemistry and Molecular Biology, The Penn State College of Medicine, Hershey, PA, USA
| | - Matthew T Swulius
- Department of Biochemistry and Molecular Biology, The Penn State College of Medicine, Hershey, PA, USA.
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19
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Yusuf M, Farooq S, Robinson I, Lalani EN. Cryo-nanoscale chromosome imaging-future prospects. Biophys Rev 2020; 12:1257-1263. [PMID: 33006727 PMCID: PMC7575669 DOI: 10.1007/s12551-020-00757-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/04/2020] [Indexed: 01/30/2023] Open
Abstract
The high-order structure of mitotic chromosomes remains to be fully elucidated. How nucleosomes compact at various structural levels into a condensed mitotic chromosome is unclear. Cryogenic preservation and imaging have been applied for over three decades, keeping biological structures close to the native in vivo state. Despite being extensively utilized, this field is still wide open for mitotic chromosome research. In this review, we focus specifically on cryogenic efforts for determining the mitotic nanoscale chromatin structures. We describe vitrification methods, current status, and applications of advanced cryo-microscopy including future tools required for resolving the native architecture of these fascinating structures that hold the instructions to life.
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Affiliation(s)
- Mohammed Yusuf
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK.
- Centre for Regenerative Medicine and Stem Cell Research, Aga Khan University, P.O.Box 3500, Karachi, 74800, Pakistan.
| | - Safana Farooq
- Centre for Regenerative Medicine and Stem Cell Research, Aga Khan University, P.O.Box 3500, Karachi, 74800, Pakistan
| | - Ian Robinson
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
- Brookhaven National Lab, Upton, NY, 11973, USA
| | - El-Nasir Lalani
- Centre for Regenerative Medicine and Stem Cell Research, Aga Khan University, P.O.Box 3500, Karachi, 74800, Pakistan
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20
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Hayles MF, DE Winter DAM. An introduction to cryo-FIB-SEM cross-sectioning of frozen, hydrated Life Science samples. J Microsc 2020; 281:138-156. [PMID: 32737879 PMCID: PMC7891420 DOI: 10.1111/jmi.12951] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/21/2020] [Accepted: 07/28/2020] [Indexed: 12/31/2022]
Abstract
The introduction of cryo‐techniques to the focused ion‐beam scanning electron microscope (FIB‐SEM) has brought new opportunities to study frozen, hydrated samples from the field of Life Sciences. Cryo‐techniques have long been employed in electron microscopy. Thin electron transparent sections are produced by cryo‐ultramicrotomy for observation in a cryo‐transmission electron microscope (TEM). Cryo‐TEM is presently reaching the imaging of macromolecular structures. In parallel, cryo‐fractured surfaces from bulk materials have been investigated by cryo‐SEM. Both cryo‐TEM and cryo‐SEM have provided a wealth of information, despite being 2D techniques. Cryo‐TEM tomography does provide 3D information, but the thickness of the volume has a maximum of 200–300 nm, which limits the 3D information within the context of specific structures. FIB‐milling enables imaging additional planes by creating cross‐sections (e.g. cross‐sectioning or site‐specific X‐sectioning) perpendicular to the cryo‐fracture surface, thus adding a third imaging dimension to the cryo‐SEM. This paper discusses how to produce suitable cryo‐FIB‐SEM cross‐section results from frozen, hydrated Life Science samples with emphasis on ‘common knowledge’ and reoccurring observations. Lay Description Life Sciences studies life down to the smallest details. Visualising the smallest details requires electron microscopy, which utilises high‐vacuum chambers. One method to maintain the integrity of Life Sciences samples under vacuum conditions is freezing. Frozen samples can remain in a suspended state. As a result, research can be carried out without having to change the chemistry or internal physical structure of the samples. Two types of electron microscopes equipped with cryo‐sample handling facilities are used to investigate samples: The scanning electron microscope (SEM) which investigates surfaces and the transmission electron microscope (TEM) which investigates thin electron transparent sections (called lamellae). A third method of investigation combines a SEM with a focused ion beam (FIB) to form a cryo‐FIB‐SEM, which is the basis of this paper. The electron beam images the cryo‐sample surface while the ion beam mills into the surface to expose the interior of the sample. The latter is called cross‐sectioning and the result provides a way of investigating the 3rd dimension of the sample. This paper looks at the making of cross‐sections in this manner originating from knowledge and experience gained with this technique over many years. This information is meant for newcomers, and experienced researchers in cryo‐microscopy alike.
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Affiliation(s)
- M F Hayles
- Cryo-FIB-SEM Technologist, Eindhoven, the Netherlands
| | - D A M DE Winter
- Environmental Hydrogeology, Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, the Netherlands
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21
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Ultee E, van der Aart LT, Zhang L, van Dissel D, Diebolder CA, van Wezel GP, Claessen D, Briegel A. Teichoic acids anchor distinct cell wall lamellae in an apically growing bacterium. Commun Biol 2020; 3:314. [PMID: 32555532 PMCID: PMC7300013 DOI: 10.1038/s42003-020-1038-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 05/28/2020] [Indexed: 11/17/2022] Open
Abstract
The bacterial cell wall is a multicomponent structure that provides structural support and protection. In monoderm species, the cell wall is made up predominantly of peptidoglycan, teichoic acids and capsular glycans. Filamentous monoderm Actinobacteria incorporate new cell-wall material at their tips. Here we use cryo-electron tomography to reveal the architecture of the actinobacterial cell wall of Streptomyces coelicolor. Our data shows a density difference between the apex and subapical regions. Removal of teichoic acids results in a patchy cell wall and distinct lamellae. Knock-down of tagO expression using CRISPR-dCas9 interference leads to growth retardation, presumably because build-in of teichoic acids had become rate-limiting. Absence of extracellular glycans produced by MatAB and CslA proteins results in a thinner wall lacking lamellae and patches. We propose that the Streptomyces cell wall is composed of layers of peptidoglycan and extracellular polymers that are structurally supported by teichoic acids.
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Affiliation(s)
- Eveline Ultee
- Department of Molecular Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Lizah T van der Aart
- Department of Molecular Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Le Zhang
- Department of Molecular Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Dino van Dissel
- Department of Molecular Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Christoph A Diebolder
- Netherlands Centre for Electron Nanoscopy (NeCEN), Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Gilles P van Wezel
- Department of Molecular Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Dennis Claessen
- Department of Molecular Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - Ariane Briegel
- Department of Molecular Biotechnology, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE, Leiden, The Netherlands.
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands.
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22
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Engel L, Gaietta G, Dow LP, Swift MF, Pardon G, Volkmann N, Weis WI, Hanein D, Pruitt BL. Extracellular matrix micropatterning technology for whole cell cryogenic electron microscopy studies. JOURNAL OF MICROMECHANICS AND MICROENGINEERING : STRUCTURES, DEVICES, AND SYSTEMS 2019; 29:115018. [PMID: 32879557 PMCID: PMC7457726 DOI: 10.1088/1361-6439/ab419a] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Cryogenic electron tomography is the highest resolution tool available for structural analysis of macromolecular organization inside cells. Micropatterning of extracellular matrix (ECM) proteins is an established in vitro cell culture technique used to control cell shape. Recent traction force microscopy studies have shown correlation between cell morphology and the regulation of force transmission. However, it remains unknown how cells sustain increased strain energy states and localized stresses at the supramolecular level. Here, we report a technology to enable direct observation of mesoscale organization in epithelial cells under morphological modulation, using a maskless protein photopatterning method (PRIMO) to confine cells to ECM micropatterns on electron microscopy substrates. These micropatterned cell culture substrates can be used in mechanobiology research to correlate changes in nanometer-scale organization at cell-cell and cell-ECM contacts to strain energy states and traction stress distribution in the cell.
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Affiliation(s)
- Leeya Engel
- Department of Bioengineering, Stanford University, Stanford, California
- Correspondence:
| | - Guido Gaietta
- Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Liam P. Dow
- Department of Bioengineering, Stanford University, Stanford, California
- Biomolecular Science and Engineering Program, University of California, Santa Barbara
| | - Mark F. Swift
- Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Gaspard Pardon
- Department of Bioengineering, Stanford University, Stanford, California
| | - Niels Volkmann
- Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - William I. Weis
- Departments of Structural Biology and Molecular and Cellular Physiology, Stanford University School of Medicine
| | - Dorit Hanein
- Immunity and Pathogenesis Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Beth L. Pruitt
- Department of Bioengineering, Stanford University, Stanford, California
- Biomolecular Science and Engineering Program, University of California, Santa Barbara
- Departments of Mechanical Engineering and Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara
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23
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A. Abd El Samad A. Transmission Electron Tomography: Intracellular Insight for the Future of Medicine. ELECTRON MICROSCOPY - NOVEL MICROSCOPY TRENDS 2019. [DOI: 10.5772/intechopen.84977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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24
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Otegui MS, Pennington JG. Electron tomography in plant cell biology. Microscopy (Oxf) 2019; 68:69-79. [PMID: 30452668 DOI: 10.1093/jmicro/dfy133] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/15/2018] [Accepted: 10/31/2018] [Indexed: 12/11/2022] Open
Abstract
Electron tomography (ET) approaches are based on the imaging of a biological specimen at different tilt angles by transmission electron microscopy (TEM). ET can be applied to both plastic-embedded and frozen samples. Technological advancements in TEM, direct electron detection, automated image collection, and imaging processing algorithms allow for 2-7-nm scale axial resolution in tomographic reconstructions of cells and organelles. In this review, we discussed the application of ET in plant cell biology and new opportunities for imaging plant cells by cryo-ET and other 3D electron microscopy approaches.
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Affiliation(s)
- Marisa S Otegui
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison WI, USA.,Laboratory of Molecular and Cellular Biology, University of Wisconsin-Madison, 1525 Linden Drive, Madison WI, USA.,Department of Genetics, University of Wisconsin-Madison, 425 Henry Mall, Madison WI, USA
| | - Jannice G Pennington
- Institute for Molecular Virology, University of Wisconsin-Madison, 1525 Linden Drive, Madison WI, USA.,Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, USA
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25
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Tomographic Collection of Block-Based Sparse STEM Images: Practical Implementation and Impact on the Quality of the 3D Reconstructed Volume. MATERIALS 2019; 12:ma12142281. [PMID: 31315199 PMCID: PMC6679239 DOI: 10.3390/ma12142281] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 01/18/2023]
Abstract
The reduction of the electron dose in electron tomography of biological samples is of high significance to diminish radiation damages. Simulations have shown that sparse data collection can perform efficient electron dose reduction. Frameworks based on compressive-sensing or inpainting algorithms have been proposed to accurately reconstruct missing information in sparse data. The present work proposes a practical implementation to perform tomographic collection of block-based sparse images in scanning transmission electron microscopy. The method has been applied on sections of chemically-fixed and resin-embedded Trypanosoma brucei cells. There are 3D reconstructions obtained from various amounts of downsampling, which are compared and eventually the limits of electron dose reduction using this method are explored.
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26
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Kaplan M, Subramanian P, Ghosal D, Oikonomou CM, Pirbadian S, Starwalt‐Lee R, Mageswaran SK, Ortega DR, Gralnick JA, El‐Naggar MY, Jensen GJ. In situ imaging of the bacterial flagellar motor disassembly and assembly processes. EMBO J 2019; 38:e100957. [PMID: 31304634 PMCID: PMC6627242 DOI: 10.15252/embj.2018100957] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 04/11/2019] [Accepted: 04/18/2019] [Indexed: 11/09/2022] Open
Abstract
The self-assembly of cellular macromolecular machines such as the bacterial flagellar motor requires the spatio-temporal synchronization of gene expression with proper protein localization and association of dozens of protein components. In Salmonella and Escherichia coli, a sequential, outward assembly mechanism has been proposed for the flagellar motor starting from the inner membrane, with the addition of each new component stabilizing the previous one. However, very little is known about flagellar disassembly. Here, using electron cryo-tomography and sub-tomogram averaging of intact Legionella pneumophila, Pseudomonas aeruginosa, and Shewanella oneidensis cells, we study flagellar motor disassembly and assembly in situ. We first show that motor disassembly results in stable outer membrane-embedded sub-complexes. These sub-complexes consist of the periplasmic embellished P- and L-rings, and bend the membrane inward while it remains apparently sealed. Additionally, we also observe various intermediates of the assembly process including an inner-membrane sub-complex consisting of the C-ring, MS-ring, and export apparatus. Finally, we show that the L-ring is responsible for reshaping the outer membrane, a crucial step in the flagellar assembly process.
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Affiliation(s)
- Mohammed Kaplan
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Poorna Subramanian
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Debnath Ghosal
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Catherine M Oikonomou
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Sahand Pirbadian
- Department of Physics and Astronomy, Biological Sciences, and ChemistryUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Ruth Starwalt‐Lee
- BioTechnology InstituteUniversity of Minnesota – Twin CitiesSt. PaulMNUSA
| | | | - Davi R Ortega
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Jeffrey A Gralnick
- BioTechnology InstituteUniversity of Minnesota – Twin CitiesSt. PaulMNUSA
- Department of Plant and Microbial BiologyUniversity of Minnesota – Twin CitiesSt. PaulMNUSA
| | - Mohamed Y El‐Naggar
- Department of Physics and Astronomy, Biological Sciences, and ChemistryUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Grant J Jensen
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
- Howard Hughes Medical InstituteCalifornia Institute of TechnologyPasadenaCAUSA
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27
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Taraska JW. A primer on resolving the nanoscale structure of the plasma membrane with light and electron microscopy. J Gen Physiol 2019; 151:974-985. [PMID: 31253697 PMCID: PMC6683668 DOI: 10.1085/jgp.201812227] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 06/10/2019] [Indexed: 12/20/2022] Open
Abstract
Taraska reviews the imaging methods that are being used to understand the structure of the plasma membrane at the molecular level. The plasma membrane separates a cell from its external environment. All materials and signals that enter or leave the cell must cross this hydrophobic barrier. Understanding the architecture and dynamics of the plasma membrane has been a central focus of general cellular physiology. Both light and electron microscopy have been fundamental in this endeavor and have been used to reveal the dense, complex, and dynamic nanoscale landscape of the plasma membrane. Here, I review classic and recent developments in the methods used to image and study the structure of the plasma membrane, particularly light, electron, and correlative microscopies. I will discuss their history and use for mapping the plasma membrane and focus on how these tools have provided a structural framework for understanding the membrane at the scale of molecules. Finally, I will describe how these studies provide a roadmap for determining the nanoscale architecture of other organelles and entire cells in order to bridge the gap between cellular form and function.
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Affiliation(s)
- Justin W Taraska
- Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
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28
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Nguyen LT, Oikonomou CM, Ding HJ, Kaplan M, Yao Q, Chang YW, Beeby M, Jensen GJ. Simulations suggest a constrictive force is required for Gram-negative bacterial cell division. Nat Commun 2019; 10:1259. [PMID: 30890709 PMCID: PMC6425016 DOI: 10.1038/s41467-019-09264-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Accepted: 02/28/2019] [Indexed: 11/16/2022] Open
Abstract
To divide, Gram-negative bacterial cells must remodel cell wall at the division site. It remains debated, however, whether this cell wall remodeling alone can drive membrane constriction, or if a constrictive force from the tubulin homolog FtsZ is required. Previously, we constructed software (REMODELER 1) to simulate cell wall remodeling during growth. Here, we expanded this software to explore cell wall division (REMODELER 2). We found that simply organizing cell wall synthesis complexes at the midcell is not sufficient to cause invagination, even with the implementation of a make-before-break mechanism, in which new hoops of cell wall are made inside the existing hoops before bonds are cleaved. Division can occur, however, when a constrictive force brings the midcell into a compressed state before new hoops of relaxed cell wall are incorporated between existing hoops. Adding a make-before-break mechanism drives division with a smaller constrictive force sufficient to bring the midcell into a relaxed, but not necessarily compressed, state.
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Affiliation(s)
- Lam T Nguyen
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
| | - Catherine M Oikonomou
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
| | - H Jane Ding
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
| | - Mohammed Kaplan
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
| | - Qing Yao
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
| | - Yi-Wei Chang
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, 422 Curie Boulevard, Philadelphia, PA, 19104, USA
| | - Morgan Beeby
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA
- Department of Life Sciences, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Boulevard, Pasadena, CA, 91125, USA.
- Howard Hughes Medical Institute, 1200 E. California Boulevard, Pasadena, CA, 91125, USA.
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29
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Kaplan M, Ghosal D, Subramanian P, Oikonomou CM, Kjaer A, Pirbadian S, Ortega DR, Briegel A, El-Naggar MY, Jensen GJ. The presence and absence of periplasmic rings in bacterial flagellar motors correlates with stator type. eLife 2019; 8:43487. [PMID: 30648971 PMCID: PMC6375700 DOI: 10.7554/elife.43487] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 12/19/2018] [Indexed: 12/22/2022] Open
Abstract
The bacterial flagellar motor, a cell-envelope-embedded macromolecular machine that functions as a cellular propeller, exhibits significant structural variability between species. Different torque-generating stator modules allow motors to operate in different pH, salt or viscosity levels. How such diversity evolved is unknown. Here, we use electron cryo-tomography to determine the in situ macromolecular structures of three Gammaproteobacteria motors: Legionella pneumophila, Pseudomonas aeruginosa, and Shewanella oneidensis, providing the first views of intact motors with dual stator systems. Complementing our imaging with bioinformatics analysis, we find a correlation between the motor’s stator system and its structural elaboration. Motors with a single H+-driven stator have only the core periplasmic P- and L-rings; those with dual H+-driven stators have an elaborated P-ring; and motors with Na+ or Na+/H+-driven stators have both their P- and L-rings embellished. Our results suggest an evolution of structural elaboration that may have enabled pathogenic bacteria to colonize higher-viscosity environments in animal hosts. Bacteria are so small that for them, making their way through water is like swimming in roofing tar for us. In response, these organisms have evolved a molecular machine that helps them move in their environment. Named the bacterial flagellum, this complex assemblage of molecules is formed of three main parts: a motor that spans the inner and outer membranes of the cell, and then a ‘hook’ that connects to a long filament which extends outside the bacterium. More precisely, the motor is formed of the stator, an ion pump that stays still, and of a rotor that can spin. Different rings can also be present in the space between the inner and outer membranes (the periplasm) and surround these components. The stator uses ions to generate the energy that makes the rotor whirl. In turn, this movement sets the filament in motion, propelling the bacterium. Depending on where the bacteria live, the stator can use different types of ions. In addition, while many species have a single stator system per motor, some may have several stator systems for one motor: this may help the microorganisms move in different conditions. As microbes colonize environments with a different pH or viscosity, they constantly evolve new versions of the motor which are more suitable to their new surroundings. However, a part of the motor remains the same across species. Overall, it is still unclear how bacterial flagella evolve, but examining the structure of new motors can shed light upon this process. Here, Kaplan et al. combine a bioinformatics approach with an imaging technique known as electron cryo-tomography to dissect the structure of the flagellar motor of three species of bacteria with different stator systems, and compare these to known motors of the same class. The results reveal a correlation between the nature of the stator system and the presence of certain elements. Stators that use sodium ions, or both sodium and hydrogen ions, are associated with two periplasmic rings surrounding the conserved motor structure. These rings do not exist in motors with single hydrogen-driven stators. Motors with dual hydrogen-driven stators are, to some extent, an ‘intermediate state’, with only one of those rings present. As all the studied species currently exist, it is difficult to know which version of the motor is the most ancient, and which one has evolved more recently. Capturing the diversity of bacterial motors gives us insight into the evolutionary forces that shape complex molecular structures, which is essential to understand how life evolved on Earth. More practically, this knowledge may also help us design better nanomachines to power microscopic robots.
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Affiliation(s)
- Mohammed Kaplan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Debnath Ghosal
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Poorna Subramanian
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Catherine M Oikonomou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Andreas Kjaer
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Sahand Pirbadian
- Department of Physics and Astronomy, Biological Sciences, and Chemistry, University of Southern California, Los Angeles, United States
| | - Davi R Ortega
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Ariane Briegel
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Mohamed Y El-Naggar
- Department of Physics and Astronomy, Biological Sciences, and Chemistry, University of Southern California, Los Angeles, United States
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States.,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States
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High Rac1 activity is functionally translated into cytosolic structures with unique nanoscale cytoskeletal architecture. Proc Natl Acad Sci U S A 2019; 116:1267-1272. [PMID: 30630946 DOI: 10.1073/pnas.1808830116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Rac1 activation is at the core of signaling pathways regulating polarized cell migration. So far, it has not been possible to directly explore the structural changes triggered by Rac1 activation at the molecular level. Here, through a multiscale imaging workflow that combines biosensor imaging of Rac1 dynamics with electron cryotomography, we identified, within the crowded environment of eukaryotic cells, a unique nanoscale architecture of a flexible, signal-dependent actin structure. In cell regions with high Rac1 activity, we found a structural regime that spans from the ventral membrane up to a height of ∼60 nm above that membrane, composed of directionally unaligned, densely packed actin filaments, most shorter than 150 nm. This unique Rac1-induced morphology is markedly different from the dendritic network architecture in which relatively short filaments emanate from existing, longer actin filaments. These Rac1-mediated scaffold assemblies are devoid of large macromolecules such as ribosomes or other filament types, which are abundant at the periphery and within the remainder of the imaged volumes. Cessation of Rac1 activity induces a complete and rapid structural transition, leading to the absence of detectable remnants of such structures within 150 s, providing direct structural evidence for rapid actin filament network turnover induced by GTPase signaling events. It is tempting to speculate that this highly dynamical nanoscaffold system is sensitive to local spatial cues, thus serving to support the formation of more complex actin filament architectures-such as those mandated by epithelial-mesenchymal transition, for example-or resetting the region by completely dissipating.
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Che C, Lin R, Zeng X, Elmaaroufi K, Galeotti J, Xu M. Improved deep learning-based macromolecules structure classification from electron cryo-tomograms. MACHINE VISION AND APPLICATIONS 2018; 29:1227-1236. [PMID: 31511756 PMCID: PMC6738941 DOI: 10.1007/s00138-018-0949-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 01/16/2018] [Accepted: 05/18/2018] [Indexed: 05/30/2023]
Abstract
Cellular processes are governed by macromolecular complexes inside the cell. Study of the native structures of macromolecular complexes has been extremely difficult due to lack of data. With recent breakthroughs in Cellular Electron Cryo-Tomography (CECT) 3D imaging technology, it is now possible for researchers to gain accesses to fully study and understand the macro-molecular structures single cells. However, systematic recovery of macromolecular structures from CECT is very difficult due to high degree of structural complexity and practical imaging limitations. Specifically, we proposed a deep learning-based image classification approach for large-scale systematic macromolecular structure separation from CECT data. However, our previous work was only a very initial step toward exploration of the full potential of deep learning-based macromolecule separation. In this paper, we focus on improving classification performance by proposing three newly designed individual CNN models: an extended version of (Deep Small Receptive Field) DSRF3D, donated as DSRF3D-v2, a 3D residual block-based neural network, named as RB3D, and a convolutional 3D (C3D)-based model, CB3D. We compare them with our previously developed model (DSRF3D) on 12 datasets with different SNRs and tilt angle ranges. The experiments show that our new models achieved significantly higher classification accuracies. The accuracies are not only higher than 0.9 on normal datasets, but also demonstrate potentials to operate on datasets with high levels of noises and missing wedge effects presented.
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Affiliation(s)
- Chengqian Che
- The Robotics Institute, Carnegie Mellon University,Pittsburgh, USA
| | - Ruogu Lin
- Department of Automation, Tsinghua University, Beijing, China
| | - Xiangrui Zeng
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, USA
| | - Karim Elmaaroufi
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, USA
| | - John Galeotti
- The Robotics Institute, Carnegie Mellon University,Pittsburgh, USA
| | - Min Xu
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, USA
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32
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Cryo-ET reveals the macromolecular reorganization of S. pombe mitotic chromosomes in vivo. Proc Natl Acad Sci U S A 2018; 115:10977-10982. [PMID: 30297429 DOI: 10.1073/pnas.1720476115] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chromosomes condense during mitosis in most eukaryotes. This transformation involves rearrangements at the nucleosome level and has consequences for transcription. Here, we use cryo-electron tomography (cryo-ET) to determine the 3D arrangement of nuclear macromolecular complexes, including nucleosomes, in frozen-hydrated Schizosaccharomyces pombe cells. Using 3D classification analysis, we did not find evidence that nucleosomes resembling the crystal structure are abundant. This observation and those from other groups support the notion that a subset of fission yeast nucleosomes may be partially unwrapped in vivo. In both interphase and mitotic cells, there is also no evidence of monolithic structures the size of Hi-C domains. The chromatin is mingled with two features: pockets, which are positions free of macromolecular complexes; and "megacomplexes," which are multimegadalton globular complexes like preribosomes. Mitotic chromatin is more crowded than interphase chromatin in subtle ways. Nearest-neighbor distance analyses show that mitotic chromatin is more compacted at the oligonucleosome than the dinucleosome level. Like interphase, mitotic chromosomes contain megacomplexes and pockets. This uneven chromosome condensation helps explain a longstanding enigma of mitosis: a subset of genes is up-regulated.
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Liu C, Zeng X, Lin R, Liang X, Freyberg Z, Xing E, Xu M. DEEP LEARNING BASED SUPERVISED SEMANTIC SEGMENTATION OF ELECTRON CRYO-SUBTOMOGRAMS. PROCEEDINGS. INTERNATIONAL CONFERENCE ON IMAGE PROCESSING 2018; 2018:1578-1582. [PMID: 37799820 PMCID: PMC10552869 DOI: 10.1109/icip.2018.8451386] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/07/2023]
Abstract
Cellular Electron Cryo-Tomography (CECT) is a powerful imaging technique for the 3D visualization of cellular structure and organization at submolecular resolution. It enables analyzing the native structures of macromolecular complexes and their spatial organization inside single cells. However, due to the high degree of structural complexity and practical imaging limitations, systematic macromolecular structural recovery inside CECT images remains challenging. Particularly, the recovery of a macromolecule is likely to be biased by its neighbor structures due to the high molecular crowding. To reduce the bias, here we introduce a novel 3D convolutional neural network inspired by Fully Convolutional Network and Encoder-Decoder Architecture for the supervised segmentation of macromolecules of interest in subtomograms. The tests of our models on realistically simulated CECT data demonstrate that our new approach has significantly improved segmentation performance compared to our baseline approach. Also, we demonstrate that the proposed model has generalization ability to segment new structures that do not exist in training data.
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Affiliation(s)
- Chang Liu
- Electrical and Computer Engineering Department, Carnegie Mellon University, USA
| | - Xiangrui Zeng
- Computational Biology Department, Carnegie Mellon University, USA
| | - Ruogu Lin
- Department of Automation, Tsinghua University, China
| | - Xiaodan Liang
- Machine Learning Department, Carnegie Mellon University, USA
| | - Zachary Freyberg
- Departments of Psychiatry and Cell Biology, University of Pittsburgh, USA
| | - Eric Xing
- Machine Learning Department, Carnegie Mellon University, USA
| | - Min Xu
- Computational Biology Department, Carnegie Mellon University, USA
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Navarro PP, Stahlberg H, Castaño-Díez D. Protocols for Subtomogram Averaging of Membrane Proteins in the Dynamo Software Package. Front Mol Biosci 2018; 5:82. [PMID: 30234127 PMCID: PMC6131572 DOI: 10.3389/fmolb.2018.00082] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/13/2018] [Indexed: 11/13/2022] Open
Abstract
Cryo-electron tomography allows low-resolution three-dimensional (3D) viewing of cellular organelles and macromolecular complexes present as multiple copies within a tomogram. These structures are computationally extracted and averaged in order to obtain high-resolution 3D structures, and provide a map of their spatial distribution and interaction with their biological microenvironment. To do so, we apply the user-friendly Dynamo software package on a tomographic data set. Dynamo acts as a modular toolbox adaptable to different biological scenarios, allowing a custom designed pipeline for subtomogram averaging. Here, we use as a textbook example the mitochondrial docking site of the positive-strand RNA Flock house nodavirus (FHV) to describe how Dynamo coordinates several basic steps in the subtomogram averaging workflow. Our framework covers specific strategies to deal with additional issues in subtomogram averaging as tomographic data management, 3D surface visualization, automatic assignment of asymmetry and inherent loss of Fourier information in presence of preferential views.
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Affiliation(s)
- Paula P Navarro
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland
| | - Henning Stahlberg
- Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland
| | - Daniel Castaño-Díez
- BioEM Lab, Center for Cellular Imaging and NanoAnalytics, Biozentrum, University of Basel, Basel, Switzerland
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35
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Dai W, Chen M, Myers C, Ludtke SJ, Pettitt BM, King JA, Schmid MF, Chiu W. Visualizing Individual RuBisCO and Its Assembly into Carboxysomes in Marine Cyanobacteria by Cryo-Electron Tomography. J Mol Biol 2018; 430:4156-4167. [PMID: 30138616 DOI: 10.1016/j.jmb.2018.08.013] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 07/29/2018] [Accepted: 08/13/2018] [Indexed: 12/31/2022]
Abstract
Cyanobacteria are photosynthetic organisms responsible for ~25% of the organic carbon fixation on earth. A key step in carbon fixation is catalyzed by ribulose bisphosphate carboxylase/oxygenase (RuBisCO), the most abundant enzyme in the biosphere. Applying Zernike phase-contrast electron cryo-tomography and automated annotation, we identified individual RuBisCO molecules and their assembly intermediates leading to the formation of carboxysomes inside Syn5 cyanophage infected cyanobacteria Synechococcus sp. WH8109 cells. Surprisingly, more RuBisCO molecules were found to be present as cytosolic free-standing complexes or clusters than as packaged assemblies inside carboxysomes. Cytosolic RuBisCO clusters and partially assembled carboxysomes identified in the cell tomograms support a concurrent assembly model involving both the protein shell and the enclosed RuBisCO. In mature carboxysomes, RuBisCO is neither randomly nor strictly icosahedrally packed within protein shells of variable sizes. A time-averaged molecular dynamics simulation showed a semi-liquid probability distribution of the RuBisCO in carboxysomes and correlated well with carboxysome subtomogram averages. Our structural observations reveal the various stages of RuBisCO assemblies, which could be important for understanding cellular function.
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Affiliation(s)
- Wei Dai
- Department of Cell Biology and Neuroscience & Institute for Quantitative Biomedicine, Rutgers University, Piscataway, NJ 08854, USA.
| | - Muyuan Chen
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Christopher Myers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Steven J Ludtke
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - B Montgomery Pettitt
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA; Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555, USA; Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Jonathan A King
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Michael F Schmid
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
| | - Wah Chiu
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA; Departments of Bioengineering and of Microbiology and Immunoplogy, James H. Clark Center, Stanford University, Stanford, CA 94305, USA.
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36
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Robust workflow and instrumentation for cryo-focused ion beam milling of samples for electron cryotomography. Ultramicroscopy 2018; 190:1-11. [DOI: 10.1016/j.ultramic.2018.04.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 03/28/2018] [Accepted: 04/04/2018] [Indexed: 01/11/2023]
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37
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Xu M, Chai X, Muthakana H, Liang X, Yang G, Zeev-Ben-Mordehai T, Xing EP. Deep learning-based subdivision approach for large scale macromolecules structure recovery from electron cryo tomograms. Bioinformatics 2018; 33:i13-i22. [PMID: 28881965 PMCID: PMC5946875 DOI: 10.1093/bioinformatics/btx230] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Motivation Cellular Electron CryoTomography (CECT) enables 3D visualization of cellular organization at near-native state and in sub-molecular resolution, making it a powerful tool for analyzing structures of macromolecular complexes and their spatial organizations inside single cells. However, high degree of structural complexity together with practical imaging limitations makes the systematic de novo discovery of structures within cells challenging. It would likely require averaging and classifying millions of subtomograms potentially containing hundreds of highly heterogeneous structural classes. Although it is no longer difficult to acquire CECT data containing such amount of subtomograms due to advances in data acquisition automation, existing computational approaches have very limited scalability or discrimination ability, making them incapable of processing such amount of data. Results To complement existing approaches, in this article we propose a new approach for subdividing subtomograms into smaller but relatively homogeneous subsets. The structures in these subsets can then be separately recovered using existing computation intensive methods. Our approach is based on supervised structural feature extraction using deep learning, in combination with unsupervised clustering and reference-free classification. Our experiments show that, compared with existing unsupervised rotation invariant feature and pose-normalization based approaches, our new approach achieves significant improvements in both discrimination ability and scalability. More importantly, our new approach is able to discover new structural classes and recover structures that do not exist in training data. Availability and Implementation Source code freely available at http://www.cs.cmu.edu/∼mxu1/software. Supplementary information Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Min Xu
- Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Xiaoqi Chai
- Biomedical Engineering Department, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Hariank Muthakana
- Computer Science Department, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Xiaodan Liang
- Machine Learning Department, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Ge Yang
- Biomedical Engineering Department, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Tzviya Zeev-Ben-Mordehai
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Eric P Xing
- Machine Learning Department, Carnegie Mellon University, Pittsburgh, PA, USA
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Weiss GL, Medeiros JM, Pilhofer M. In Situ Imaging of Bacterial Secretion Systems by Electron Cryotomography. Methods Mol Biol 2018; 1615:353-375. [PMID: 28667625 DOI: 10.1007/978-1-4939-7033-9_27] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The unique property of electron cryotomography (ECT) is its capability to resolve the structure of macromolecular machines in their cellular context. The integration of ECT data with high-resolution structures of purified subcomplexes and live-cell fluorescence light microscopy can generate pseudo-atomic models that lead to a mechanistic understanding across size and time scales. Recent advances in electron detection, sample thinning, data acquisition, and data processing have significantly enhanced the applicability and performance of ECT. Here we describe a detailed workflow for an ECT experiment, including cell culture, vitrification, data acquisition, data reconstruction, tomogram analysis, and subtomogram averaging. This protocol provides an entry point to the technique for students and researchers and indicates the many possible variations arising from specific target properties and the available instrumentation.
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Affiliation(s)
- Gregor L Weiss
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - João M Medeiros
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, 8093, Zürich, Switzerland
| | - Martin Pilhofer
- Department of Biology, ETH Zürich, Institute of Molecular Biology and Biophysics, Otto-Stern-Weg 5, 8093, Zürich, Switzerland.
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39
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Ultrastructure of Shewanella oneidensis MR-1 nanowires revealed by electron cryotomography. Proc Natl Acad Sci U S A 2018; 115:E3246-E3255. [PMID: 29555764 DOI: 10.1073/pnas.1718810115] [Citation(s) in RCA: 107] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial nanowires have garnered recent interest as a proposed extracellular electron transfer (EET) pathway that links the bacterial electron transport chain to solid-phase electron acceptors away from the cell. Recent studies showed that Shewanella oneidensis MR-1 produces outer membrane (OM) and periplasmic extensions that contain EET components and hinted at their possible role as bacterial nanowires. However, their fine structure and distribution of cytochrome electron carriers under native conditions remained unclear, making it difficult to evaluate the potential electron transport (ET) mechanism along OM extensions. Here, we report high-resolution images of S. oneidensis OM extensions, using electron cryotomography (ECT). We developed a robust method for fluorescence light microscopy imaging of OM extension growth on electron microscopy grids and used correlative light and electron microscopy to identify and image the same structures by ECT. Our results reveal that S. oneidensis OM extensions are dynamic chains of interconnected outer membrane vesicles (OMVs) with variable dimensions, curvature, and extent of tubulation. Junction densities that potentially stabilize OMV chains are seen between neighboring vesicles in cryotomograms. By comparing wild type and a cytochrome gene deletion mutant, our ECT results provide the likely positions and packing of periplasmic and outer membrane proteins consistent with cytochromes. Based on the observed cytochrome packing density, we propose a plausible ET path along the OM extensions involving a combination of direct hopping and cytochrome diffusion. A mean-field calculation, informed by the observed ECT cytochrome density, supports this proposal by revealing ET rates on par with a fully packed cytochrome network.
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40
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Abstract
Cell division in many eukaryotes is driven by a ring containing actin and myosin. While much is known about the main proteins involved, the precise arrangement of actin filaments within the contractile machinery, and how force is transmitted to the membrane, remains unclear. Here we use cryosectioning and cryofocused ion beam milling to gain access to cryopreserved actomyosin rings in Schizosaccharomyces pombe for direct 3D imaging by electron cryotomography. Our results show that straight, overlapping actin filaments, running nearly parallel to each other and to the membrane, form a loose bundle of ∼150 nm in diameter that "saddles" the inward-bending membrane at the leading edge of the division septum. The filaments do not make direct contact with the membrane. Our analysis of the actin filaments reveals the variability in filament number, nearest-neighbor distances between filaments within the bundle, their distance from the membrane, and angular distribution with respect to the membrane.
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41
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Abstract
Cryo-electron microscopy (cryo-EM) allows the imaging of intact macromolecular complexes in the context of whole cells. The biological samples for cryo-EM are kept in a near-native state by flash freezing, without the need for any additional sample preparation or fixation steps. Since transmission electron microscopy only generates 2D projections of the samples, the specimen has to be tilted in order to recover its 3D structural information. This is done by collecting images of the sample with various tilt angles in respect to the electron beam. The acquired tilt series can then be computationally back-projected. This technique is called electron cryotomography (ECT), and has been instrumental in unraveling the architecture of chemoreceptor arrays. Here we describe the method of visualizing in vivo bacterial chemoreceptor arrays in three main steps: immobilization of bacterial cells on EM grids by plunge-freezing; 2D image acquisition in tilt series; and 3D tomogram reconstruction.
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Affiliation(s)
- Wen Yang
- Department of Biology, Leiden University, Leiden, The Netherlands
| | - Ariane Briegel
- Department of Biology, Leiden University, Leiden, The Netherlands.
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42
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Shimomura K, Hirose M, Takahashi Y. Multislice imaging of integrated circuits by precession X-ray ptychography. ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES 2018; 74:66-70. [PMID: 29269599 DOI: 10.1107/s205327331701525x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/19/2017] [Indexed: 11/10/2022]
Abstract
A method for nondestructively visualizing multisection nanostructures of integrated circuits by X-ray ptychography with a multislice approach is proposed. In this study, tilt-series ptychographic diffraction data sets of a two-layered circuit with a ∼1.4 µm gap at nine incident angles are collected in a wide Q range and then artifact-reduced phase images of each layer are successfully reconstructed at ∼10 nm resolution. The present method has great potential for the three-dimensional observation of flat specimens with thickness on the order of 100 µm, such as three-dimensional stacked integrated circuits based on through-silicon vias, without laborious sample preparation.
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Affiliation(s)
- Kei Shimomura
- Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Makoto Hirose
- Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yukio Takahashi
- Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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Wagner J, Schaffer M, Fernández-Busnadiego R. Cryo-electron tomography-the cell biology that came in from the cold. FEBS Lett 2017; 591:2520-2533. [PMID: 28726246 DOI: 10.1002/1873-3468.12757] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 06/26/2017] [Accepted: 07/14/2017] [Indexed: 12/27/2022]
Abstract
Cryo-electron tomography (cryo-ET) provides high-resolution 3D views into cells pristinely preserved by vitrification. Recent technical advances such as direct electron detectors, the Volta phase plate and cryo-focused ion beam milling have dramatically pushed image quality and expanded the range of cryo-ET applications. Cryo-ET not only allows mapping the positions and interactions of macromolecules within their intact cellular context, but can also reveal their in situ structure at increasing resolution. Here, we review how recent work using cutting-edge cryo-ET technologies is starting to provide fresh views into different aspects of cellular biology at an unprecedented level of detail. We anticipate that these developments will soon make cryo-ET a fundamental technique in cell biology.
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Abstract
Electron cryotomography (ECT) provides three-dimensional views of macromolecular complexes inside cells in a native frozen-hydrated state. Over the last two decades, ECT has revealed the ultrastructure of cells in unprecedented detail. It has also allowed us to visualize the structures of macromolecular machines in their native context inside intact cells. In many cases, such machines cannot be purified intact for in vitro study. In other cases, the function of a structure is lost outside the cell, so that the mechanism can be understood only by observation in situ. In this review, we describe the technique and its history and provide examples of its power when applied to cell biology. We also discuss the integration of ECT with other techniques, including lower-resolution fluorescence imaging and higher-resolution atomic structure determination, to cover the full scale of cellular processes.
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Affiliation(s)
- Catherine M Oikonomou
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; ,
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; , .,Howard Hughes Medical Institute, Pasadena, California 91125
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Trépout S, Bastin P, Marco S. Preparation and Observation of Thick Biological Samples by Scanning Transmission Electron Tomography. J Vis Exp 2017. [PMID: 28362414 DOI: 10.3791/55215] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
This report describes a protocol for preparing thick biological specimens for further observation using a scanning transmission electron microscope. It also describes an imaging method for studying the 3D structure of thick biological specimens by scanning transmission electron tomography. The sample preparation protocol is based on conventional methods in which the sample is fixed using chemical agents, treated with a heavy atom salt contrasting agent, dehydrated in a series of ethanol baths, and embedded in resin. The specific imaging conditions for observing thick samples by scanning transmission electron microscopy are then described. Sections of the sample are observed using a through-focus method involving the collection of several images at various focal planes. This enables the recovery of in-focus information at various heights throughout the sample. This particular collection pattern is performed at each tilt angle during tomography data collection. A single image is then generated, merging the in-focus information from all the different focal planes. A classic tilt-series dataset is then generated. The advantage of the method is that the tilt-series alignment and reconstruction can be performed using standard tools. The collection of through-focal images allows the reconstruction of a 3D volume that contains all of the structural details of the sample in focus.
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Affiliation(s)
| | - Philippe Bastin
- Institut Pasteur, Trypanosome Cell Biology Unit, Department of Parasites & Insect Vectors, INSERM U1201
| | - Sergio Marco
- Institut Curie, INSERM U1196, Campus Universitaire d'Orsay
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Briegel A, Jensen G. Progress and Potential of Electron Cryotomography as Illustrated by Its Application to Bacterial Chemoreceptor Arrays. Annu Rev Biophys 2017; 46:1-21. [PMID: 28301773 DOI: 10.1146/annurev-biophys-070816-033555] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electron cryotomography (ECT) can produce three-dimensional images of biological samples such as intact cells in a near-native, frozen-hydrated state to macromolecular resolution (∼4 nm). Because one of its first and most common applications has been to bacterial chemoreceptor arrays, ECT's contributions to this field illustrate well its past, present, and future. While X-ray crystallography and nuclear magnetic resonance spectroscopy have revealed the structures of nearly all the individual components of chemoreceptor arrays, ECT has revealed the mesoscale information about how the components are arranged within cells. Receptors assemble into a universally conserved 12-nm hexagonal lattice linked by CheA/CheW rings. Membrane-bound arrays are single layered; cytoplasmic arrays are double layered. Images of in vitro reconstitutions have led to a model of how arrays assemble, and images of native arrays in different states have shown that the conformational changes associated with signal transduction are subtle, constraining models of activation and system cooperativity. Phase plates, better detectors, and more stable stages promise even higher resolution and broader application in the near future.
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Affiliation(s)
- Ariane Briegel
- Department of Biology, Leiden University, 2333 Leiden, Netherlands
| | - Grant Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125; .,Howard Hughes Medical Institute, Pasadena, California 91125
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48
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Cserti E, Rosskopf S, Chang YW, Eisheuer S, Selter L, Shi J, Regh C, Koert U, Jensen GJ, Thanbichler M. Dynamics of the peptidoglycan biosynthetic machinery in the stalked budding bacteriumHyphomonas neptunium. Mol Microbiol 2017; 103:875-895. [DOI: 10.1111/mmi.13593] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2016] [Indexed: 12/14/2022]
Affiliation(s)
- Emöke Cserti
- Faculty of Biology; Philipps-Universität; Marburg 35043 Germany
- Max Planck Institute for Terrestrial Microbiology; Marburg 35043 Germany
| | - Sabine Rosskopf
- Faculty of Biology; Philipps-Universität; Marburg 35043 Germany
| | - Yi-Wei Chang
- Division of Biology and Bioengineering; California Institute of Technology; Pasadena CA 91125 USA
| | - Sabrina Eisheuer
- Faculty of Biology; Philipps-Universität; Marburg 35043 Germany
- Max Planck Institute for Terrestrial Microbiology; Marburg 35043 Germany
| | - Lars Selter
- Faculty of Chemistry; Philipps-Universität; Marburg Germany
| | - Jian Shi
- Division of Biology and Bioengineering; California Institute of Technology; Pasadena CA 91125 USA
| | - Christina Regh
- Faculty of Biology; Philipps-Universität; Marburg 35043 Germany
| | - Ulrich Koert
- Faculty of Chemistry; Philipps-Universität; Marburg Germany
| | - Grant J. Jensen
- Division of Biology and Bioengineering; California Institute of Technology; Pasadena CA 91125 USA
- Howard Hughes Medical Institute, California Institute of Technology; Pasadena CA 91125 USA
| | - Martin Thanbichler
- Faculty of Biology; Philipps-Universität; Marburg 35043 Germany
- Max Planck Institute for Terrestrial Microbiology; Marburg 35043 Germany
- LOEWE Center for Synthetic Microbiology; Marburg 35043 Germany
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Shami GJ, Cheng D, Huynh M, Vreuls C, Wisse E, Braet F. 3-D EM exploration of the hepatic microarchitecture - lessons learned from large-volume in situ serial sectioning. Sci Rep 2016; 6:36744. [PMID: 27834401 PMCID: PMC5105151 DOI: 10.1038/srep36744] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/20/2016] [Indexed: 12/12/2022] Open
Abstract
To-date serial block-face scanning electron microscopy (SBF-SEM) dominates as the premier technique for generating three-dimensional (3-D) data of resin-embedded biological samples at an unprecedented depth volume. Given the infancy of the technique, limited literature is currently available regarding the applicability of SBF-SEM for the ultrastructural investigation of tissues. Herein, we provide a comprehensive and rigorous appraisal of five different SBF-SEM sample preparation protocols for the large-volume exploration of the hepatic microarchitecture at an unparalleled X, Y and Z resolution. In so doing, we qualitatively and quantitatively validate the use of a comprehensive SBF-SEM sample preparation protocol, based on the application of heavy metal fixatives, stains and mordanting agents. Employing the best-tested SBF-SEM approach, enabled us to assess large-volume morphometric data on murine parenchymal cells, sinusoids and bile canaliculi. Finally, we integrated the validated SBF-SEM protocol with a correlative light and electron microscopy (CLEM) approach. The combination of confocal scanning laser microscopy and SBF-SEM provided a novel way to picture subcellular detail. We appreciate that this multidimensional approach will aid the subsequent research of liver tissue under relevant experimental and disease conditions.
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Affiliation(s)
- Gerald John Shami
- School of Medical Sciences (Discipline of Anatomy and Histology) – The Bosch Institute, The University of Sydney, NSW 2006, Australia
| | - Delfine Cheng
- School of Medical Sciences (Discipline of Anatomy and Histology) – The Bosch Institute, The University of Sydney, NSW 2006, Australia
| | - Minh Huynh
- Australian Centre for Microscopy and Microanalysis (ACMM), The University of Sydney, NSW 2006, Australia
| | - Celien Vreuls
- Department of Pathology, Amphia Hospital, Breda, The Netherlands
| | - Eddie Wisse
- Australian Centre for Microscopy and Microanalysis (ACMM), The University of Sydney, NSW 2006, Australia
- Maastricht Multimodal Molecular Imaging Institute, Division of Nanoscopy, University of Maastricht, 6200 MD Maastricht, The Netherlands
- Department of Internal Medicine, University of Maastricht, 6200, MD Maastricht, The Netherlands
| | - Filip Braet
- School of Medical Sciences (Discipline of Anatomy and Histology) – The Bosch Institute, The University of Sydney, NSW 2006, Australia
- Australian Centre for Microscopy and Microanalysis (ACMM), The University of Sydney, NSW 2006, Australia
- Cellular Imaging Facility, Charles Perkins Centre, The University of Sydney, NSW 2006, Australia
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50
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Chemotaxis cluster 1 proteins form cytoplasmic arrays in Vibrio cholerae and are stabilized by a double signaling domain receptor DosM. Proc Natl Acad Sci U S A 2016; 113:10412-7. [PMID: 27573843 DOI: 10.1073/pnas.1604693113] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nearly all motile bacterial cells use a highly sensitive and adaptable sensory system to detect changes in nutrient concentrations in the environment and guide their movements toward attractants and away from repellents. The best-studied bacterial chemoreceptor arrays are membrane-bound. Many motile bacteria contain one or more additional, sometimes purely cytoplasmic, chemoreceptor systems. Vibrio cholerae contains three chemotaxis clusters (I, II, and III). Here, using electron cryotomography, we explore V. cholerae's cytoplasmic chemoreceptor array and establish that it is formed by proteins from cluster I. We further identify a chemoreceptor with an unusual domain architecture, DosM, which is essential for formation of the cytoplasmic arrays. DosM contains two signaling domains and spans the two-layered cytoplasmic arrays. Finally, we present evidence suggesting that this type of receptor is important for the structural stability of the cytoplasmic array.
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