1
|
Zhou L, Shi W, Fu S, Li M, Chen J, Fang K, Li Y. High Refractive Index Imaging Buffer for Dual-Color 3D SMLM Imaging of Thick Samples. Anal Chem 2024; 96:15648-15656. [PMID: 39298273 DOI: 10.1021/acs.analchem.4c02893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2024]
Abstract
The current limitations of single-molecule localization microscopy (SMLM) in deep tissue imaging, primarily due to depth-dependent aberrations caused by refractive index (RI) mismatch, present a significant challenge in achieving high-resolution images at greater depths. To extend the imaging depth, we optimized the imaging buffer of SMLM with the RI matched to that of the objective immersion medium and systematically evaluated five different RI-matched buffers, focusing on their impact on the blinking behavior of red-absorbing dyes and the quality of reconstructed super-resolution images. Particularly, we found that clear unobstructed brain imaging cocktails-based imaging buffer could match the RI of oil and was able to clear the tissue samples. With the help of the RI-matched imaging buffers, we showed high-quality dual-color 3D SMLM images with imaging depths ranging from a few micrometers to tens of micrometers in both cultured cells and sectioned tissue samples. This advancement offers a practical and accessible method for high-resolution imaging at greater depths without the need for specialized optical equipment or expertise.
Collapse
Affiliation(s)
- Lulu Zhou
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Wei Shi
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Shuang Fu
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Mengfan Li
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jianwei Chen
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Ke Fang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yiming Li
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
2
|
Vatan T, Minehart JA, Zhang C, Agarwal V, Yang J, Speer CM. Volumetric super-resolution imaging by serial ultrasectioning and stochastic optical reconstruction microscopy in mouse neural tissue. STAR Protoc 2021; 2:100971. [PMID: 34901889 PMCID: PMC8637648 DOI: 10.1016/j.xpro.2021.100971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Here, we present a protocol for collecting large-volume, four-color, single-molecule localization imaging data from neural tissue. We have applied this technique to map the location and identities of chemical synapses across whole cells in mouse retinae. Our sample preparation approach improves 3D STORM image quality by reducing tissue scattering, photobleaching, and optical distortions associated with deep imaging. This approach can be extended for use on other tissue types enabling life scientists to perform volumetric super-resolution imaging in diverse biological models. For complete details on the use and execution of this protocol, please refer to Sigal et al. (2015).
Collapse
Affiliation(s)
- Tarlan Vatan
- Department of Biology, University of Maryland, College Park, MD 20742, USA
- Neuroscience and Cognitive Science Graduate Program, University of Maryland, College Park, MD 20742, USA
| | - Jacqueline A. Minehart
- Department of Biology, University of Maryland, College Park, MD 20742, USA
- Neuroscience and Cognitive Science Graduate Program, University of Maryland, College Park, MD 20742, USA
| | - Chenghang Zhang
- Department of Biology, University of Maryland, College Park, MD 20742, USA
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742, USA
| | - Vatsal Agarwal
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Jerry Yang
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Colenso M. Speer
- Department of Biology, University of Maryland, College Park, MD 20742, USA
- Brain and Behavior Institute, University of Maryland, College Park, MD 20742, USA
| |
Collapse
|
3
|
Kempf N, Moutahir F, Goiffon I, Cantaloube S, Bystricky K, Lavigne AC. Analysis of Cellular EMT States Using Molecular Biology and High Resolution FISH Labeling. Methods Mol Biol 2021; 2179:353-383. [PMID: 32939733 DOI: 10.1007/978-1-0716-0779-4_27] [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: 01/10/2023]
Abstract
Metastasis results from the ability of cancer cells to grow and to spread beyond the primary tumor to distant organs. Epithelial-to-Mesenchymal Transition (EMT), a fundamental developmental process, is reactivated in cancer cells, and causes epithelial properties to evolve into mesenchymal and invasive ones. EMT changes cellular characteristics between two distinct states, yet, the process is not binary but rather reflects a broad spectrum of partial EMT states in which cells exhibit various degrees of intermediate epithelial and mesenchymal phenotypes. EMT is a complex multistep process that involves cellular reprogramming through numerous signaling pathways, alterations in gene expression, and changes in chromatin morphology. Therefore, expression of key proteins, including cadherins, occludin, or vimentin must be precisely regulated. A comprehensive understanding of how changes in nuclear organization, at the level of single genes clusters, correlates with these processes during formation of metastatic cells is still missing and yet may help personalized prognosis and treatment in the clinic. Here, we describe methods to correlate physiological and molecular states of cells undergoing an EMT process with chromatin rearrangements observed via FISH labeling of specific domains.
Collapse
Affiliation(s)
- Noémie Kempf
- Center for Integrative Biology (CBI), Laboratoire de Biologie Moléculaire des Eucaryotes (LBME), University of Toulouse, UPS, CNRS, F-31062 Toulouse, France
| | - Fatima Moutahir
- Center for Integrative Biology (CBI), Laboratoire de Biologie Moléculaire des Eucaryotes (LBME), University of Toulouse, UPS, CNRS, F-31062 Toulouse, France
| | - Isabelle Goiffon
- Center for Integrative Biology (CBI), Laboratoire de Biologie Moléculaire des Eucaryotes (LBME), University of Toulouse, UPS, CNRS, F-31062 Toulouse, France
| | - Sylvain Cantaloube
- Center for Integrative Biology (CBI), Laboratoire de Biologie Moléculaire des Eucaryotes (LBME), University of Toulouse, UPS, CNRS, F-31062 Toulouse, France
| | - Kerstin Bystricky
- Center for Integrative Biology (CBI), Laboratoire de Biologie Moléculaire des Eucaryotes (LBME), University of Toulouse, UPS, CNRS, F-31062 Toulouse, France
| | - Anne-Claire Lavigne
- Center for Integrative Biology (CBI), Laboratoire de Biologie Moléculaire des Eucaryotes (LBME), University of Toulouse, UPS, CNRS, F-31062 Toulouse, France.
| |
Collapse
|
4
|
Su JH, Zheng P, Kinrot SS, Bintu B, Zhuang X. Genome-Scale Imaging of the 3D Organization and Transcriptional Activity of Chromatin. Cell 2020; 182:1641-1659.e26. [PMID: 32822575 PMCID: PMC7851072 DOI: 10.1016/j.cell.2020.07.032] [Citation(s) in RCA: 276] [Impact Index Per Article: 69.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 06/19/2020] [Accepted: 07/21/2020] [Indexed: 12/30/2022]
Abstract
The 3D organization of chromatin regulates many genome functions. Our understanding of 3D genome organization requires tools to directly visualize chromatin conformation in its native context. Here we report an imaging technology for visualizing chromatin organization across multiple scales in single cells with high genomic throughput. First we demonstrate multiplexed imaging of hundreds of genomic loci by sequential hybridization, which allows high-resolution conformation tracing of whole chromosomes. Next we report a multiplexed error-robust fluorescence in situ hybridization (MERFISH)-based method for genome-scale chromatin tracing and demonstrate simultaneous imaging of more than 1,000 genomic loci and nascent transcripts of more than 1,000 genes together with landmark nuclear structures. Using this technology, we characterize chromatin domains, compartments, and trans-chromosomal interactions and their relationship to transcription in single cells. We envision broad application of this high-throughput, multi-scale, and multi-modal imaging technology, which provides an integrated view of chromatin organization in its native structural and functional context.
Collapse
Affiliation(s)
- Jun-Han Su
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, and Department of Physics, Harvard University, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Pu Zheng
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, and Department of Physics, Harvard University, Cambridge, MA 02138, USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | - Seon S Kinrot
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, and Department of Physics, Harvard University, Cambridge, MA 02138, USA; Graduate Program in Biophysics, Harvard University, Cambridge, MA 02138, USA
| | - Bogdan Bintu
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, and Department of Physics, Harvard University, Cambridge, MA 02138, USA.
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, and Department of Physics, Harvard University, Cambridge, MA 02138, USA.
| |
Collapse
|
5
|
Abstract
Recent advances in super-resolution (sub-diffraction limited) microscopy have yielded remarkable insights into the nanoscale architecture and behavior of cells. In addition to the capacity to provide sub 100 nm resolution, these technologies offer unique quantitative opportunities with particular relevance to platelet and megakaryocyte biology. In this review, we provide a short introduction to modern super-resolution microscopy, its applications in the field of platelet and megakaryocyte biology, and emerging quantitative approaches which will allow for unprecedented insights into the biology of these unique cell types.
Collapse
Affiliation(s)
- Abdullah O Khan
- Institute of Cardiovascular Sciences, College of Medical and Dental Science, University of Birmingham , Birmingham, UK
| | - Jeremy A Pike
- Institute of Cardiovascular Sciences, College of Medical and Dental Science, University of Birmingham , Birmingham, UK.,Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham , UK
| |
Collapse
|
6
|
Schmider AB, Bauer NC, Sunwoo H, Godin MD, Ellis GE, Lee JT, Nigrovic PA, Soberman RJ. Two- and three-color STORM analysis reveals higher-order assembly of leukotriene synthetic complexes on the nuclear envelope of murine neutrophils. J Biol Chem 2020; 295:5761-5770. [PMID: 32152223 PMCID: PMC7186161 DOI: 10.1074/jbc.ra119.012069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 02/24/2020] [Indexed: 11/06/2022] Open
Abstract
Over the last several years it has become clear that higher order assemblies on membranes, exemplified by signalosomes, are a paradigm for the regulation of many membrane signaling processes. We have recently combined two-color direct stochastic optical reconstruction microscopy (dSTORM) with the (Clus-DoC) algorithm that combines cluster detection and colocalization analysis to observe the organization of 5-lipoxygenase (5-LO) and 5-lipoxygenase-activating protein (FLAP) into higher order assemblies on the nuclear envelope of mast cells; these assemblies were linked to leukotriene (LT) C4 production. In this study we investigated whether higher order assemblies of 5-LO and FLAP included cytosolic phospholipase A2 (cPLA2) and were linked to LTB4 production in murine neutrophils. Using two- and three-color dSTORM supported by fluorescence lifetime imaging microscopy we identified higher order assemblies containing 40 molecules (median) (IQR: 23, 87) of 5-LO, and 53 molecules (62, 156) of FLAP monomer. 98 (18, 154) molecules of cPLA2 were clustered with 5-LO, and 77 (33, 114) molecules of cPLA2 were associated with FLAP. These assemblies were tightly linked to LTB4 formation. The activation-dependent close associations of cPLA2, FLAP, and 5-LO in higher order assemblies on the nuclear envelope support a model in which arachidonic acid is generated by cPLA2 in apposition to FLAP, facilitating its transfer to 5-LO to initiate LT synthesis.
Collapse
Affiliation(s)
- Angela B Schmider
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Nicholas C Bauer
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Hongjae Sunwoo
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114
| | - Matthew D Godin
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Giorgianna E Ellis
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Peter A Nigrovic
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Roy J Soberman
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129.
| |
Collapse
|
7
|
Fu Y, Jing Y, Gao J, Li Z, Wang H, Cai M, Tong T. Variation of Trop2 on non-small-cell lung cancer and normal cell membranes revealed by super-resolution fluorescence imaging. Talanta 2019; 207:120312. [PMID: 31594569 DOI: 10.1016/j.talanta.2019.120312] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 08/24/2019] [Accepted: 09/02/2019] [Indexed: 12/27/2022]
Abstract
Transmembrane glycoprotein Trop2 is related to many epithelial carcinomas. It not only plays roles in promoting fetal lung growth but also participates in tumor genesis, malignant transformation, and tumor dissemination. However, the detailed distribution of Trop2 at the molecular level remains unknown. Herein, we used direct stochastic optical reconstruction microscopy to reveal the spatial organization of Trop2 on the membranes of cultured and primary lung cancer cells and normal cells. All types of cancer cells presented more localizations of Trop2 than normal cells. By SR-Teseller cluster analysis, we found that Trop2 existed in the form of clusters on all the membranes; however, cancer cells generated more and larger clusters consisting of more molecules than normal cells. Our findings shed light on the heterogeneous distribution of membrane Trop2 and highlighted the significant differences of its clustering characteristics between lung cancer cells and normal cells, which laid the basis for further studying the mechanism and functions of Trop2 clustering in lung cancer.
Collapse
Affiliation(s)
- Yilin Fu
- The Second Hospital of Jilin University, Changchun, Jilin 130041, China
| | - Yingying Jing
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China; University of Science and Technology of China, Hefei, Anhui, 230027, China
| | - Jing Gao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Zihao Li
- The Second Hospital of Jilin University, Changchun, Jilin 130041, China
| | - Hongda Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Mingjun Cai
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China
| | - Ti Tong
- The Second Hospital of Jilin University, Changchun, Jilin 130041, China.
| |
Collapse
|
8
|
Schmider AB, Vaught M, Bauer NC, Elliott HL, Godin MD, Ellis GE, Nigrovic PA, Soberman RJ. The organization of leukotriene biosynthesis on the nuclear envelope revealed by single molecule localization microscopy and computational analyses. PLoS One 2019; 14:e0211943. [PMID: 30735559 PMCID: PMC6368329 DOI: 10.1371/journal.pone.0211943] [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: 07/10/2018] [Accepted: 01/24/2019] [Indexed: 12/21/2022] Open
Abstract
The initial steps in the synthesis of leukotrienes are the translocation of 5-lipoxygenase (5-LO) to the nuclear envelope and its subsequent association with its scaffold protein 5-lipoxygenase-activating protein (FLAP). A major gap in our understanding of this process is the knowledge of how the organization of 5-LO and FLAP on the nuclear envelope regulates leukotriene synthesis. We combined single molecule localization microscopy with Clus-DoC cluster analysis, and also a novel unbiased cluster analysis to analyze changes in the relationships between 5-LO and FLAP in response to activation of RBL-2H3 cells to generate leukotriene C4. We identified the time-dependent reorganization of both 5-LO and FLAP into higher-order assemblies or clusters in response to cell activation via the IgE receptor. Clus-DoC analysis identified a subset of these clusters with a high degree of interaction between 5-LO and FLAP that specifically correlates with the time course of LTC4 synthesis, strongly suggesting their role in the initiation of leukotriene biosynthesis.
Collapse
Affiliation(s)
- Angela B. Schmider
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Melissa Vaught
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Nicholas C. Bauer
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Hunter L. Elliott
- Image and Data Analysis Core, Department of Cell Biology, Harvard Medical School, Boston, MA, United States of America
| | - Matthew D. Godin
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Giorgianna E. Ellis
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Peter A. Nigrovic
- Division of Rheumatology, Immunology and Allergy, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, United States of America
| | - Roy J. Soberman
- Nephrology Division, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States of America
- * E-mail:
| |
Collapse
|
9
|
Bintu B, Mateo LJ, Su JH, Sinnott-Armstrong NA, Parker M, Kinrot S, Yamaya K, Boettiger AN, Zhuang X. Super-resolution chromatin tracing reveals domains and cooperative interactions in single cells. Science 2018; 362:eaau1783. [PMID: 30361340 PMCID: PMC6535145 DOI: 10.1126/science.aau1783] [Citation(s) in RCA: 532] [Impact Index Per Article: 88.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/04/2018] [Indexed: 12/15/2022]
Abstract
The spatial organization of chromatin is pivotal for regulating genome functions. We report an imaging method for tracing chromatin organization with kilobase- and nanometer-scale resolution, unveiling chromatin conformation across topologically associating domains (TADs) in thousands of individual cells. Our imaging data revealed TAD-like structures with globular conformation and sharp domain boundaries in single cells. The boundaries varied from cell to cell, occurring with nonzero probabilities at all genomic positions but preferentially at CCCTC-binding factor (CTCF)- and cohesin-binding sites. Notably, cohesin depletion, which abolished TADs at the population-average level, did not diminish TAD-like structures in single cells but eliminated preferential domain boundary positions. Moreover, we observed widespread, cooperative, multiway chromatin interactions, which remained after cohesin depletion. These results provide critical insight into the mechanisms underlying chromatin domain and hub formation.
Collapse
Affiliation(s)
- Bogdan Bintu
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology and Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Leslie J Mateo
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Jun-Han Su
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology and Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | | | - Mirae Parker
- Department of Physics, Stanford University, Stanford, CA 94305, USA
| | - Seon Kinrot
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology and Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Kei Yamaya
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA
| | - Alistair N Boettiger
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology and Department of Physics, Harvard University, Cambridge, MA 02138, USA.
| |
Collapse
|
10
|
Abstract
The past decade has witnessed an explosion in the use of super-resolution fluorescence microscopy methods in biology and other fields. Single-molecule localization microscopy (SMLM) is one of the most widespread of these methods and owes its success in large part to the ability to control the on-off state of fluorophores through various chemical, photochemical, or binding-unbinding mechanisms. We provide here a comprehensive overview of switchable fluorophores in SMLM including a detailed review of all major classes of SMLM fluorophores, and we also address strategies for labeling specimens, considerations for multichannel and live-cell imaging, potential pitfalls, and areas for future development.
Collapse
Affiliation(s)
- Honglin Li
- Department of Chemistry, University of Washington, Seattle, Washington, USA, 98195
| | - Joshua C. Vaughan
- Department of Chemistry, University of Washington, Seattle, Washington, USA, 98195
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA, 98195
| |
Collapse
|
11
|
Leduc C, Salles A, Shorte SL, Etienne-Manneville S. Imaging Intermediate Filaments and Microtubules with 2-dimensional Direct Stochastic Optical Reconstruction Microscopy. J Vis Exp 2018. [PMID: 29578510 DOI: 10.3791/57087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The cytoskeleton, composed of actin microfilaments, microtubules, and intermediate filaments (IF), plays a key role in the control of cell shape, polarity, and motility. The organization of the actin and microtubule networks has been extensively studied but that of IFs is not yet fully characterized. IFs have an average diameter of 10 nm and form a network extending throughout the cell cytoplasm. They are physically associated with actin and microtubules through molecular motors and cytoskeletal linkers. This tight association is at the heart of the regulatory mechanisms that ensure the coordinated regulation of the three cytoskeletal networks required for most cell functions. It is therefore crucial to visualize IFs alone and also together with each of the other cytoskeletal networks. However, IF networks are extremely dense in most cell types, especially in glial cells, which makes its resolution very difficult to achieve with standard fluorescence microscopy (lateral resolution of ~250 nm). Direct STochastic Optical Reconstruction Microscopy (dSTORM) is a technique allowing a gain in lateral resolution of one order of magnitude. Here, we show that lateral dSTORM resolution is sufficient to resolve the dense organization of the IF networks and, in particular, of IF bundles surrounding microtubules. Such tight association is likely to participate in the coordinated regulation of these two networks and may, explain how vimentin IFs template and stabilize microtubule organization as well as could influence microtubule dependent vesicular trafficking. More generally, we show how the observation of two cytoskeletal components with dual-color dSTORM technique brings new insight into their mutual interaction.
Collapse
Affiliation(s)
- Cécile Leduc
- Cell Polarity, Migration and Cancer Unit, UMR 3691, CNRS, Institut Pasteur;
| | - Audrey Salles
- UTechS Photonic BioImaging (Imagopole) Citech, Institut Pasteur
| | | | | |
Collapse
|
12
|
Bartle EI, Rao TC, Urner TM, Mattheyses AL. Bridging the gap: Super-resolution microscopy of epithelial cell junctions. Tissue Barriers 2018; 6:e1404189. [PMID: 29420122 PMCID: PMC5823550 DOI: 10.1080/21688370.2017.1404189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 02/02/2023] Open
Abstract
Cell junctions are critical for cell adhesion and communication in epithelial tissues. It is evident that the cellular distribution, size, and architecture of cell junctions play a vital role in regulating function. These details of junction architecture have been challenging to elucidate in part due to the complexity and size of cell junctions. A major challenge in understanding these features is attaining high resolution spatial information with molecular specificity. Fluorescence microscopy allows localization of specific proteins to junctions, but with a resolution on the same scale as junction size, rendering internal protein organization unobtainable. Super-resolution microscopy provides a bridge between fluorescence microscopy and nanoscale approaches, utilizing fluorescent tags to reveal protein organization below the resolution limit. Here we provide a brief introduction to super-resolution microscopy and discuss novel findings into the organization, structure and function of epithelial cell junctions.
Collapse
Affiliation(s)
- Emily I. Bartle
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tejeshwar C. Rao
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Tara M. Urner
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Alexa L. Mattheyses
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| |
Collapse
|
13
|
Nikić-Spiegel I. Genetic Code Expansion- and Click Chemistry-Based Site-Specific Protein Labeling for Intracellular DNA-PAINT Imaging. Methods Mol Biol 2018; 1728:279-295. [PMID: 29405005 DOI: 10.1007/978-1-4939-7574-7_18] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Super-resolution microscopy allows imaging of cellular structures at nanometer resolution. This comes with a demand for small labels which can be attached directly to the structures of interest. In the context of protein labeling, one way to achieve this is by using genetic code expansion (GCE) and click chemistry. With GCE, small labeling handles in the form of noncanonical amino acids (ncAAs) are site-specifically introduced into a target protein. In a subsequent step, these amino acids can be directly labeled with small organic dyes by click chemistry reactions. Click chemistry labeling can also be combined with other methods, such as DNA-PAINT in which a "clickable" oligonucleotide is first attached to the ncAA-bearing target protein and then labeled with complementary fluorescent oligonucleotides. This protocol will cover both aspects: I describe (1) how to encode ncAAs and perform intracellular click chemistry-based labeling with an improved GCE system for eukaryotic cells and (2) how to combine click chemistry-based labeling with DNA-PAINT super-resolution imaging. As an example, I show click-PAINT imaging of vimentin and low-abundance nuclear protein, nucleoporin 153.
Collapse
Affiliation(s)
- Ivana Nikić-Spiegel
- Werner Reichardt Centre for Integrative Neuroscience, The Eberhard Karls University of Tübingen, Tübingen, Germany.
| |
Collapse
|
14
|
Zhao Z, Xin B, Li L, Huang ZL. High-power homogeneous illumination for super-resolution localization microscopy with large field-of-view. OPTICS EXPRESS 2017; 25:13382-13395. [PMID: 28788875 DOI: 10.1364/oe.25.013382] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 05/27/2017] [Indexed: 06/07/2023]
Abstract
As a wide-field imaging technique, super-resolution localization microscopy (SRLM) is theoretically capable of increasing field-of-view (FOV) without sacrificing either imaging speed or spatial resolution. There are two key factors for realizing large FOV SRLM: one is high-power illumination over the whole FOV with sufficient illumination homogeneity and the other is large FOV signal detection by a camera that has large number of pixels and sufficient detection sensitivity. However nowadays, even though the state-of-art scientific complementary metal-oxide semiconductor (sCMOS) cameras provide single molecule fluorescence signal detection ability over an FOV of more than 200 μm × 200 μm, large FOV SRLM still has not been achieved due to the lack of high-power homogeneous illumination. In this paper, we report large FOV SRLM with a high-power homogeneous illumination system. We demonstrate experimentally that our illumination system, which is based on a newly designed multimode fiber combiner, is capable of providing sufficient illumination intensity (~4.7 kW/cm2 @ 640 nm) and excellent illumination homogeneity. Compared with the reported approaches, our illumination system is advantageous in laser power scaling and square-shape illumination without beam clipping. As a result, our system makes full use of the sensor of a representative Hamamatsu Flash 4.0 V2 sCMOS camera (2048 × 2048 active pixels) and achieves a FOV as large as 221 μm × 221 μm with homogeneous spatial resolution. The flexible solution for realizing large FOV SRLM reported in this paper pushes a significant step toward the development of SRLM.
Collapse
|
15
|
Borrell KL, Cancglin C, Stinger BL, DeFrates KG, Caputo GA, Wu C, Vaden TD. An Experimental and Molecular Dynamics Study of Red Fluorescent Protein mCherry in Novel Aqueous Amino Acid Ionic Liquids. J Phys Chem B 2017; 121:4823-4832. [PMID: 28425717 DOI: 10.1021/acs.jpcb.7b03582] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The search for biocompatible ionic liquids (ILs) with novel biochemical and biomedical applications has recently gained greater attention. In this report, we characterize the effects of two novel amino acid-based aqueous ILs composed of tetramethylguanidinium (TMG) and amino acids on the structure and stability of a widely used red fluorescent protein (mCherry). Our experimental data shows that while the aspartic acid-based IL (TMGAsp) has effects similar to previously studied conventional ILs (BMIBF4, EMIAc, and TMGAc), the alanine-based IL (TMGAla) has a much stronger destabilization effect on the protein structure. Addition of 0.30 M TMGAla to mCherry decreases the unfolding temperature from 83 to 60 °C. Even at 25 °C, TMGAla results in a blue shift of the mCherry absorbance and fluorescence peaks and an increased Stokes shift. Molecular dynamics simulations show that the chromophore conformation and its interaction with mCherry with TMGAla are changed relative to those with TMGAsp or in the absence of ILs. Protein-ILs contact analysis indicates that the mCherry-Asp interactions are hydrophilic but the (fewer) mCherry-Ala interactions are more hydrophobic and may modulate the TMG interaction with the protein. Hence, the anion hydrophobicity may explain the special TMGAla destabilization of mCherry.
Collapse
Affiliation(s)
- Kelsey L Borrell
- Department of Chemistry and Biochemistry amd ‡Department of Biomedical and Translational Sciences, Rowan University , 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States
| | - Christine Cancglin
- Department of Chemistry and Biochemistry amd ‡Department of Biomedical and Translational Sciences, Rowan University , 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States
| | - Brittany L Stinger
- Department of Chemistry and Biochemistry amd ‡Department of Biomedical and Translational Sciences, Rowan University , 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States
| | - Kelsey G DeFrates
- Department of Chemistry and Biochemistry amd ‡Department of Biomedical and Translational Sciences, Rowan University , 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States
| | - Gregory A Caputo
- Department of Chemistry and Biochemistry amd ‡Department of Biomedical and Translational Sciences, Rowan University , 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States
| | - Chun Wu
- Department of Chemistry and Biochemistry amd ‡Department of Biomedical and Translational Sciences, Rowan University , 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States
| | - Timothy D Vaden
- Department of Chemistry and Biochemistry amd ‡Department of Biomedical and Translational Sciences, Rowan University , 201 Mullica Hill Road, Glassboro, New Jersey 08028, United States
| |
Collapse
|
16
|
Ye P, Yu H, Houshmandi M. Three/four-dimensional (3D/4D) microscopic imaging and processing in clinical dental research. BMC Oral Health 2016; 16:84. [PMID: 27586147 PMCID: PMC5009657 DOI: 10.1186/s12903-016-0282-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/20/2016] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Confocal laser scanning microscope (CLSM) has been widely employed in our laboratory for structural and functional analysis of clinical dental specimens and live cell imaging of cultured oral epithelial cells. METHODS In this vitro study, a Fluoview 1000 (Olympus) confocal system was utilised to study thick sections of carious lesions (40-100 μm) and periodontal disease tissue samples (20-40 μm) by 2D Z stacking imaging and 3-dimentional (3D) reconstruction. Four-dimensional (4D) imaging when including time or position points was used for live cells to assess penetration/localisation/co-localization of oral pathogen proteins and therapeutic drugs. RESULTS Three-dimensional (3D) reconstruction revealed latent features of carious hard tissues (strongly expressed amelogenin proteins in dentin tubules), and soft tissues (increased glial markers GFAP and S100B in pulp components). We also found the oral microbial specific pathogens, Porphyromonas gingivalis to be widely localised inside the periodontal pocket epithelial tissues as detected by 3D reconstruction from a series of 2D sections from periodontal disease tissue samples. 4D live cell imaging showed the diffusion patterns of fluorescent molecules in response to a bacterial virulence factor, the pathogen (gingipain haemagglutinin) domain that attacked epithelial integrity. This technology also showed uptake of a novel porphyrin-linked metronidazole antibiotic into epithelial cells to kill intracellular oral pathogen, P. gingivalis. CONCLUSIONS Three/four-dimensional (3D/4D) imaging and processing in confocal microscopy is of great interest and benefit to clinical dental researchers.
Collapse
Affiliation(s)
- Ping Ye
- Institute of Dental Research, Oral Health, Westmead Hospital, Westmead, Australia. .,Affiliation of Faculty of Dentistry, the University of Sydney, Sydney, Australia.
| | - Hong Yu
- Microscopy Laboratory, Westmead Institute for Medical Research, Westmead, Australia
| | - Mojgan Houshmandi
- Institute of Dental Research, Oral Health, Westmead Hospital, Westmead, Australia
| |
Collapse
|
17
|
Kaplan C, Yu C, Ewers H. Ashbya gossypii as a model system to study septin organization by single-molecule localization microscopy. Methods Cell Biol 2016; 136:161-82. [PMID: 27473909 DOI: 10.1016/bs.mcb.2016.04.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Heteromeric complexes of GTP-binding proteins from the septin family assemble into higher order structures that are essential for cell division in many organisms. The correct organization of the subunits into filaments, gauzes, and rings is the basis of septin function in this process. Electron microscopy and polarization fluorescence microscopy contributed greatly to the understanding of the dynamics and organization of such structures. However, both methods show technical limitations in resolution and specificity that do not allow the identification of individual septin complexes in assemblies in intact cells. Single-molecule localization-based fluorescence superresolution microscopy methods combine the resolution of cellular structures at the nanometer level with highest molecular specificity and excellent contrast. Here, we provide a protocol that enables the investigation of the organization of septin complexes in higher order structures in cells by combining advantageous features of the model organism Ashbya gossypii with single-molecule localization microscopy. Our assay is designed to investigate the general assembly mechanism of septin complexes in cells and is applicable to many cell types.
Collapse
Affiliation(s)
| | - C Yu
- ETH Zurich, Zurich, Switzerland
| | - H Ewers
- ETH Zurich, Zurich, Switzerland
| |
Collapse
|
18
|
Sydor AM, Czymmek KJ, Puchner EM, Mennella V. Super-Resolution Microscopy: From Single Molecules to Supramolecular Assemblies. Trends Cell Biol 2015; 25:730-748. [DOI: 10.1016/j.tcb.2015.10.004] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/03/2015] [Accepted: 10/05/2015] [Indexed: 11/25/2022]
|
19
|
Studying neuronal microtubule organization and microtubule-associated proteins using single molecule localization microscopy. Methods Cell Biol 2015; 131:127-49. [PMID: 26794511 DOI: 10.1016/bs.mcb.2015.06.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The formation and maintenance of highly polarized neurons critically depends on the proper organization of the microtubule (MT) cytoskeleton. In axons, MTs are uniformly oriented with their plus-end pointing outward whereas in mature dendrites MTs have mixed orientations. MT organization and dynamics can be regulated by MT-associated proteins (MAPs). Plus-end tracking proteins are specialized MAPs that decorate plus-ends of growing MTs and regulate neuronal polarity, neurite extension, and dendritic spine morphology. Conventional fluorescence microscopy enables observation of specific cellular components through molecule-specific labeling but provides limited resolution (∼250 nm). Therefore, electron microscopy has until now provided most of our knowledge about the precise MT organization in neurons. In the past decade, super-resolution fluorescence microscopy techniques have emerged that circumvent the diffraction limit of light and enable high-resolution reconstruction of the MT network combined with selective protein labeling. However, preserving MT ultrastructure, MAP binding, high labeling density, and antibody specificity after fixation protocols is still quite challenging. In this chapter, we provide an optimized protocol for two-color direct stochastic optical reconstruction microscopy imaging of neuronal MTs together with their growing plus-ends to probe MT architecture and polarity.
Collapse
|
20
|
Kaplan C, Ewers H. Optimized sample preparation for single-molecule localization-based superresolution microscopy in yeast. Nat Protoc 2015; 10:1007-21. [DOI: 10.1038/nprot.2015.060] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
21
|
Mennella V, Hanna R, Kim M. Subdiffraction resolution microscopy methods for analyzing centrosomes organization. Methods Cell Biol 2015; 129:129-152. [PMID: 26175437 DOI: 10.1016/bs.mcb.2015.03.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In this chapter, we describe the current methods of examining the structure of centrosomes by fluorescence subdiffraction microscopy. By using recently developed microscopy techniques, centrosomal proteins can now be examined in cells with a resolution of only a few nanometers, a level of molecular detail beyond the reach of traditional cell biology methods as confocal and widefield microscopy. We emphasize imaging by three-dimensional structured illumination microscopy, stochastic optical reconstruction microscopy, and quantitative approaches to image data analysis.
Collapse
Affiliation(s)
- Vito Mennella
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada; Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada; Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
| | - Rachel Hanna
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada; Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| | - Moshe Kim
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada; Cell Biology Program, The Hospital for Sick Children, Toronto, ON, Canada
| |
Collapse
|
22
|
Bittel AM, Saldivar IS, Dolman N, Nickerson A, Lin LJ, Nan X, Gibbs SL. Effect of Labeling Density and Time Post Labeling on Quality of Antibody-Based Super Resolution Microscopy Images. PROCEEDINGS OF SPIE--THE INTERNATIONAL SOCIETY FOR OPTICAL ENGINEERING 2015; 9331:93310M. [PMID: 32280156 PMCID: PMC7148159 DOI: 10.1117/12.2083209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Super resolution microscopy (SRM) has overcome the historic spatial resolution limit of light microscopy, enabling fluorescence visualization of intracellular structures and multi-protein complexes at the nanometer scale. Using single-molecule localization microscopy, the precise location of a stochastically activated population of photoswitchable fluorophores is determined during the collection of many images to form a single image with resolution of ~10-20 nm, an order of magnitude improvement over conventional microscopy. One of the key factors in achieving such resolution with single-molecule SRM is the ability to accurately locate each fluorophore while it emits photons. Image quality is also related to appropriate labeling density of the entity of interest within the sample. While ease of detection improves as entities are labeled with more fluorophores and have increased fluorescence signal, there is potential to reduce localization precision, and hence resolution, with an increased number of fluorophores that are on at the same time in the same relative vicinity. In the current work, fixed microtubules were antibody labeled using secondary antibodies prepared with a range of Alexa Fluor 647 conjugation ratios to compare image quality of microtubules to the fluorophore labeling density. It was found that image quality changed with both the fluorophore labeling density and time between completion of labeling and performance of imaging study, with certain fluorophore to protein ratios giving optimal imaging results.
Collapse
Affiliation(s)
- Amy M Bittel
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon 97201
| | - Isaac S Saldivar
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon 97201
| | - Nicholas Dolman
- Molecular Probes Labeling and Detection Technologies, Thermo Fisher Scientific, Eugene, Oregon 97402
| | - Andrew Nickerson
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon 97201
| | - Li-Jung Lin
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon 97201
| | - Xiaolin Nan
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon 97201
- Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon 97201
- Oregon Center for Spatial Systems Biology, Oregon Health and Science University, Portland, Oregon 97201
| | - Summer L Gibbs
- Department of Biomedical Engineering, Oregon Health and Science University, Portland, Oregon 97201
- Knight Cancer Institute, Oregon Health and Science University, Portland, Oregon 97201
- Oregon Center for Spatial Systems Biology, Oregon Health and Science University, Portland, Oregon 97201
| |
Collapse
|
23
|
Coltharp C, Yang X, Xiao J. Quantitative analysis of single-molecule superresolution images. Curr Opin Struct Biol 2014; 28:112-21. [PMID: 25179006 DOI: 10.1016/j.sbi.2014.08.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/14/2014] [Accepted: 08/14/2014] [Indexed: 10/24/2022]
Abstract
This review highlights the quantitative capabilities of single-molecule localization-based superresolution imaging methods. In addition to revealing fine structural details, the molecule coordinate lists generated by these methods provide the critical ability to quantify the number, clustering, and colocalization of molecules with 10-50 nm resolution. Here we describe typical workflows and precautions for quantitative analysis of single-molecule superresolution images. These guidelines include potential pitfalls and essential control experiments, allowing critical assessment and interpretation of superresolution images.
Collapse
Affiliation(s)
- Carla Coltharp
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xinxing Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| |
Collapse
|
24
|
Abstract
In recent years, there has been an enormous increase in the publication of spatial and temporal measurements made on fluorescence microscopy digital images. Quantitative fluorescence microscopy is a powerful and important tool in biological research but is also an error-prone technique that requires careful attention to detail. In this chapter, we focus on general concepts that are critical to performing accurate and precise quantitative fluorescence microscopy measurements.
Collapse
|
25
|
Abstract
Conventional light and fluorescence microscopy techniques have offered tremendous insight into cellular processes and structures. Their resolution is however intrinsically limited by diffraction. Superresolution techniques achieve an order of magnitude higher resolution. Among these, localization microscopy relies on the position determination of single emitters with nanometer accuracy, which allows the subsequent reconstruction of an image of the target structure. In this chapter, we provide general guidelines for localization microscopy with a focus on Saccharomyces cerevisiae. Its different cellular architecture complicates efforts to directly transfer protocols established in mammalian cells to yeast. We compare different methodologies to label structures of interest and provide protocols for the respective sample preparation, which are not limited to yeast. Using these guidelines, nanoscopic subcellular structures in yeast can be investigated by localization microscopy, which perfectly complements live-cell fluorescence and electron microscopy.
Collapse
Affiliation(s)
- Markus Mund
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany
| | | | - Jonas Ries
- European Molecular Biology Laboratory, Cell Biology and Biophysics Unit, Heidelberg, Germany
| |
Collapse
|