1
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Mäntylä E, Verkade P. Some Guiding Principles for a "Simple" Correlative Light Electron Microscopy Experiment. Methods Mol Biol 2024; 2800:89-102. [PMID: 38709480 DOI: 10.1007/978-1-0716-3834-7_8] [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
In recent years, Correlative Multimodal Imaging (CMI) has become an "en vogue" technique and a bit of a buzzword. It entails combining information from different imaging modalities to extract more information from a sample that would otherwise not be possible from each individual technique. The best established CMI technology is correlative light and electron microscopy (CLEM), which applies light and electron microscopy on the exact same sample/structure. In general, it entails the detection of fluorescently tagged proteins or structures by light microscopy and subsequently their relative intracellular localization is determined with nanometer resolution using transmission electron microscopy (TEM). Here, we describe the different steps involved in a "simple" CLEM approach. We describe the overall workflow, instrumentation, and basic principles of sample preparation for a CLEM experiment exploiting stable expression of fluorescent proteins.
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Affiliation(s)
- Elina Mäntylä
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Paul Verkade
- School of Biochemistry, University of Bristol, Bristol, UK.
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2
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Heiligenstein X, Lucas MS. One for All, All for One: A Close Look at In-Resin Fluorescence Protocols for CLEM. Front Cell Dev Biol 2022; 10:866472. [PMID: 35846358 PMCID: PMC9280628 DOI: 10.3389/fcell.2022.866472] [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: 01/31/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
Sample preparation is the novel bottleneck for high throughput correlative light and electron microscopy (CLEM). Protocols suitable for both imaging methods must therefore balance the requirements of each technique. For fluorescence light microscopy, a structure of interest can be targeted using: 1) staining, which is often structure or tissue specific rather than protein specific, 2) dye-coupled proteins or antibodies, or 3) genetically encoded fluorescent proteins. Each of these three methods has its own advantages. For ultrastructural investigation by electron microscopy (EM) resin embedding remains a significant sample preparation approach, as it stabilizes the sample such that it withstands the vacuum conditions of the EM, and enables long-term storage. Traditionally, samples are treated with heavy metal salts prior to resin embedding, in order to increase imaging contrast for EM. This is particularly important for volume EM (vEM) techniques. Yet, commonly used contrasting agents (e.g., osmium tetroxide, uranyl acetate) tend to impair fluorescence. The discovery that fluorescence can be preserved in resin-embedded specimens after mild heavy metal staining was a game changer for CLEM. These so-called in-resin fluorescence protocols present a significant leap forward for CLEM approaches towards high precision localization of a fluorescent signal in (volume) EM data. Integrated microscopy approaches, combining LM and EM detection into a single instrument certainly require such an “all in one” sample preparation. Preserving, or adding, dedicated fluorescence prior to resin embedding requires a compromise, which often comes at the expense of EM imaging contrast and membrane visibility. Especially vEM can be strongly hampered by a lack of heavy metal contrasting. This review critically reflects upon the fundamental aspects of resin embedding with regard to 1) specimen fixation and the physics and chemistry underlying the preservation of protein structure with respect to fluorescence and antigenicity, 2) optimization of EM contrast for transmission or scanning EM, and 3) the choice of embedding resin. On this basis, various existing workflows employing in-resin fluorescence are described, highlighting their common features, discussing advantages and disadvantages of the respective approach, and finally concluding with promising future developments for in-resin CLEM.
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Affiliation(s)
| | - Miriam S. Lucas
- Scientific Center for Light and Electron Microscopy (ScopeM), ETH Zurich, Zurich, Switzerland
- *Correspondence: Miriam S. Lucas,
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3
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Tagliatti E, Cortese K. Imaging Endocytosis Dynamics in Health and Disease. MEMBRANES 2022; 12:membranes12040393. [PMID: 35448364 PMCID: PMC9028293 DOI: 10.3390/membranes12040393] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/16/2022] [Accepted: 03/29/2022] [Indexed: 02/06/2023]
Abstract
Endocytosis is a critical process for cell growth and viability. It mediates nutrient uptake, guarantees plasma membrane homeostasis, and generates intracellular signaling cascades. Moreover, it plays an important role in dead cell clearance and defense against external microbes. Finally, endocytosis is an important cellular route for the delivery of nanomedicines for therapeutic treatments. Thus, it is not surprising that both environmental and genetic perturbation of endocytosis have been associated with several human conditions such as cancer, neurological disorders, and virus infections, among others. Over the last decades, a lot of research has been focused on developing advanced imaging methods to monitor endocytosis events with high resolution in living cells and tissues. These include fluorescence imaging, electron microscopy, and correlative and super-resolution microscopy. In this review, we outline the major endocytic pathways and briefly discuss how defects in the molecular machinery of these pathways lead to disease. We then discuss the current imaging methodologies used to study endocytosis in different contexts, highlighting strengths and weaknesses.
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Affiliation(s)
- Erica Tagliatti
- Laboratory of Pharmacology and Brain Pathology, Humanitas Clinical and Research Center, Via Manzoni 56, 20089 Milano, Italy
- Department of Clinical and Experimental Epilepsy, UCL Queen Square Institute of Neurology, University College London, London WC1E 6BT, UK
- Correspondence: (E.T.); (K.C.)
| | - Katia Cortese
- Cellular Electron Microscopy Laboratory, Department of Experimental Medicine (DIMES), Human Anatomy, Università di Genova, Via Antonio de Toni 14, 16132 Genova, Italy
- Correspondence: (E.T.); (K.C.)
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4
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Baatsen P, Gabarre S, Vints K, Wouters R, Vandael D, Goodchild R, Munck S, Gounko NV. Preservation of Fluorescence Signal and Imaging Optimization for Integrated Light and Electron Microscopy. Front Cell Dev Biol 2022; 9:737621. [PMID: 34977003 PMCID: PMC8715528 DOI: 10.3389/fcell.2021.737621] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/25/2021] [Indexed: 11/13/2022] Open
Abstract
Life science research often needs to define where molecules are located within the complex environment of a cell or tissue. Genetically encoded fluorescent proteins and or fluorescence affinity-labeling are the go-to methods. Although recent fluorescent microscopy methods can provide localization of fluorescent molecules with relatively high resolution, an ultrastructural context is missing. This is solved by imaging a region of interest with correlative light and electron microscopy (CLEM). We have adopted a protocol that preserves both genetically-encoded and antibody-derived fluorescent signals in resin-embedded cell and tissue samples and provides high-resolution electron microscopy imaging of the same thin section. This method is particularly suitable for dedicated CLEM instruments that combine fluorescence and electron microscopy optics. In addition, we optimized scanning EM imaging parameters for samples of varying thicknesses. These protocols will enable rapid acquisition of CLEM information from samples and can be adapted for three-dimensional EM.
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Affiliation(s)
- Pieter Baatsen
- VIB-KU Leuven Center for Brain and Disease Research, Electron Microscopy Platform and VIB-Bioimaging Core, Leuven, Belgium.,KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium
| | - Sergio Gabarre
- VIB-KU Leuven Center for Brain and Disease Research, Electron Microscopy Platform and VIB-Bioimaging Core, Leuven, Belgium.,KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium.,VIB-KU Leuven Center for Brain and Disease Research, Light Microscopy Expertise Unit and VIB Bioimaging Core, Leuven, Belgium
| | - Katlijn Vints
- VIB-KU Leuven Center for Brain and Disease Research, Electron Microscopy Platform and VIB-Bioimaging Core, Leuven, Belgium.,KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium
| | - Rosanne Wouters
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium.,VIB-KU Leuven Center for Brain and Disease Research, Laboratory for Membrane Trafficking, Leuven, Belgium
| | - Dorien Vandael
- VIB-KU Leuven Center for Brain and Disease Research, Electron Microscopy Platform and VIB-Bioimaging Core, Leuven, Belgium.,KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium
| | - Rose Goodchild
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium.,VIB-KU Leuven Center for Brain and Disease Research, Laboratory for Dystonia Research, Leuven, Belgium
| | - Sebastian Munck
- KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium.,VIB-KU Leuven Center for Brain and Disease Research, Light Microscopy Expertise Unit and VIB Bioimaging Core, Leuven, Belgium
| | - Natalia V Gounko
- VIB-KU Leuven Center for Brain and Disease Research, Electron Microscopy Platform and VIB-Bioimaging Core, Leuven, Belgium.,KU Leuven Department of Neurosciences, Leuven Brain Institute, Leuven, Belgium
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5
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Maria Ranieri A, Vezzelli M, Leslie KG, Huang S, Stagni S, Jacquemin D, Jiang H, Hubbard A, Rigamonti L, Watkin ELJ, Ogden MI, New EJ, Massi M. Structure illumination microscopy imaging of lipid vesicles in live bacteria with naphthalimide-appended organometallic complexes. Analyst 2021; 146:3818-3822. [PMID: 34036982 DOI: 10.1039/d1an00363a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
There is a lack of molecular probes for imaging bacteria, in comparison to the array of such tools available for the imaging of mammalian cells. Here, organometallic molecular probes have been developed and assessed for bacterial imaging, designed to have the potential to support multiple imaging modalities. The chemical structure of the probes is designed around a metal-naphthalimide structure. The 4-amino-1,8-naphthalimide moiety, covalently appended through a pyridine ancillary ligand, acts as a luminescent probe for super-resolution microscopy. On the other hand, the metal centre, rhenium(i) or platinum(ii) in the current study, enables techniques such as nanoSIMS. While the rhenium(i) complex was not sufficiently stable to be used as a probe, the platinum(ii) analogue showed good chemical and biological stability. Structured illumination microscopy (SIM) imaging on live Bacillus cereus confirmed the suitability of the probe for super-resolution microscopy. NanoSIMS analysis was used to monitor the uptake of the platinum(ii) complex within the bacteria and demonstrate the potential of this chemical architecture to enable multimodal imaging. The successful combination of these two moieties introduces a platform that could lead to a versatile range of multi-functional probes for bacteria.
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Affiliation(s)
- Anna Maria Ranieri
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, WA, Australia.
| | - Matteo Vezzelli
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
| | - Kathryn G Leslie
- School of Chemistry, The University of Sydney, 2006 NSW, Australia.
| | - Song Huang
- Centre for Microscopy, Characterisation and Analysis, Univsersity of Western Australia, 6009 Perth, WA, Australia
| | - Stefano Stagni
- Dipartimento di Chimica Industriale "Toso Montanari", Università degli Studi di Bologna, viale del Risorgimento 4, 40136 Bologna, Italy
| | - Denis Jacquemin
- Laboratoire CEISAM, UMR CNRS 6230, Universit8 de Nantes, 2 Rue de la HoussiniHre, BP 92208, 44322 Nantes Cedex 3, France
| | - Haibo Jiang
- Centre for Microscopy, Characterisation and Analysis, Univsersity of Western Australia, 6009 Perth, WA, Australia
| | - Alysia Hubbard
- Centre for Microscopy, Characterisation and Analysis, Univsersity of Western Australia, 6009 Perth, WA, Australia
| | - Luca Rigamonti
- Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Modena e Reggio Emilia, via G. Campi 103, 41125 Modena, Italy
| | - Elizabeth L J Watkin
- Curtin Medical School, Curtin University, Kent Street, Bentley 6102 WA, Australia
| | - Mark I Ogden
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, WA, Australia.
| | - Elizabeth J New
- School of Chemistry, The University of Sydney, 2006 NSW, Australia.
| | - Massimiliano Massi
- School of Molecular and Life Sciences, Curtin University, Bentley 6102, WA, Australia.
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6
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Wenzel M, Dekker MP, Wang B, Burggraaf MJ, Bitter W, van Weering JRT, Hamoen LW. A flat embedding method for transmission electron microscopy reveals an unknown mechanism of tetracycline. Commun Biol 2021; 4:306. [PMID: 33686188 PMCID: PMC7940657 DOI: 10.1038/s42003-021-01809-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 02/05/2021] [Indexed: 12/20/2022] Open
Abstract
Transmission electron microscopy of cell sample sections is a popular technique in microbiology. Currently, ultrathin sectioning is done on resin-embedded cell pellets, which consumes milli- to deciliters of culture and results in sections of randomly orientated cells. This is problematic for rod-shaped bacteria and often precludes large-scale quantification of morphological phenotypes due to the lack of sufficient numbers of longitudinally cut cells. Here we report a flat embedding method that enables observation of thousands of longitudinally cut cells per single section and only requires microliter culture volumes. We successfully applied this technique to Bacillus subtilis, Escherichia coli, Mycobacterium bovis, and Acholeplasma laidlawii. To assess the potential of the technique to quantify morphological phenotypes, we monitored antibiotic-induced changes in B. subtilis cells. Surprisingly, we found that the ribosome inhibitor tetracycline causes membrane deformations. Further investigations showed that tetracycline disturbs membrane organization and localization of the peripheral membrane proteins MinD, MinC, and MreB. These observations are not the result of ribosome inhibition but constitute a secondary antibacterial activity of tetracycline that so far has defied discovery.
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Affiliation(s)
- Michaela Wenzel
- Bacterial Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands.
- Department of Medical Microbiology and Infection Control, Amsterdam University Medical Centers - Location VUMC, 1081 HZ, Amsterdam, The Netherlands.
- Chemical Biology, Department for Biology and Biological Engineering, Chalmers University of Technology, 412 96, Gothenburg, Sweden.
| | - Marien P Dekker
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, Amsterdam University Medical Centers - Location VUMC, 1081 HZ, Amsterdam, The Netherlands
| | - Biwen Wang
- Bacterial Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Maroeska J Burggraaf
- Department of Medical Microbiology and Infection Control, Amsterdam University Medical Centers - Location VUMC, 1081 HZ, Amsterdam, The Netherlands
| | - Wilbert Bitter
- Department of Medical Microbiology and Infection Control, Amsterdam University Medical Centers - Location VUMC, 1081 HZ, Amsterdam, The Netherlands
- Department of Molecular Cell Biology, Amsterdam Institute for Molecules, Medicines, and Systems, Faculty of Science, Vrije Universiteit Amsterdam, 1081 HZ, Amsterdam, The Netherlands
| | - Jan R T van Weering
- Department of Clinical Genetics, Center for Neurogenomics and Cognitive Research (CNCR), Neuroscience Campus Amsterdam, Amsterdam University Medical Centers - Location VUMC, 1081 HZ, Amsterdam, The Netherlands.
| | - Leendert W Hamoen
- Bacterial Cell Biology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
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7
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An accelerated procedure for approaching and imaging of optically branded region of interest in tissue. Methods Cell Biol 2020; 162:205-221. [PMID: 33707013 DOI: 10.1016/bs.mcb.2020.08.002] [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] [Indexed: 01/04/2023]
Abstract
Many areas of biology have benefited from advances in light microscopy (LM). However, one limitation of the LM approach is that numerous critically important aspects of subcellular machineries are well beyond the resolution of conventional LM. For studying these, electron microscopy (EM) remains the technique of choice to visualize and identify macromolecules at the ultrastructural level. The most powerful approach is combining both techniques, LM and EM (i.e., to apply correlative light/electron microscopy, CLEM) to image exactly the same region of interest. This combination allows, for example, to immuno-localize proteins by LM and then to visualize the ultrastructural context of the same region of the sample. However, the identification and correlation of the regions of interest (ROIs) at the levels of LM and EM remains a major challenge, mostly due to the difficulties with correlation along the Z-axis for both modalities. In this chapter, we address this difficulty and describe an approach for performing CLEM in tissue samples using marks from near-infrared branding as indicators of a ROI, and then using serial block face-scanning electron microscopy (SBF-SEM) to identify and approach this ROI. Once a ROI has been approached, serial sections are collected on grids for high-resolution imaging by transmission EM, and subsequent correlation with LM images showing labeled proteins.
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8
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Fuest M, Schaffer M, Nocera GM, Galilea-Kleinsteuber RI, Messling JE, Heymann M, Plitzko JM, Burg TP. In situ Microfluidic Cryofixation for Cryo Focused Ion Beam Milling and Cryo Electron Tomography. Sci Rep 2019; 9:19133. [PMID: 31836773 PMCID: PMC6911106 DOI: 10.1038/s41598-019-55413-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 11/27/2019] [Indexed: 11/30/2022] Open
Abstract
We present a microfluidic platform for studying structure-function relationships at the cellular level by connecting video rate live cell imaging with in situ microfluidic cryofixation and cryo-electron tomography of near natively preserved, unstained specimens. Correlative light and electron microscopy (CLEM) has been limited by the time required to transfer live cells from the light microscope to dedicated cryofixation instruments, such as a plunge freezer or high-pressure freezer. We recently demonstrated a microfluidic based approach that enables sample cryofixation directly in the light microscope with millisecond time resolution, a speed improvement of up to three orders of magnitude. Here we show that this cryofixation method can be combined with cryo-electron tomography (cryo-ET) by using Focused Ion Beam milling at cryogenic temperatures (cryo-FIB) to prepare frozen hydrated electron transparent sections. To make cryo-FIB sectioning of rapidly frozen microfluidic channels achievable, we developed a sacrificial layer technique to fabricate microfluidic devices with a PDMS bottom wall <5 µm thick. We demonstrate the complete workflow by rapidly cryo-freezing Caenorhabditis elegans roundworms L1 larvae during live imaging in the light microscope, followed by cryo-FIB milling and lift out to produce thin, electron transparent sections for cryo-ET imaging. Cryo-ET analysis of initial results show that the structural preservation of the cryofixed C. elegans was suitable for high resolution cryo-ET work. The combination of cryofixation during live imaging enabled by microfluidic cryofixation with the molecular resolution capabilities of cryo-ET offers an exciting avenue to further advance space-time correlative light and electron microscopy (st-CLEM) for investigation of biological processes at high resolution in four dimensions.
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Affiliation(s)
- Marie Fuest
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Miroslava Schaffer
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Giovanni Marco Nocera
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | | | - Jan-Erik Messling
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Michael Heymann
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany.,Institute of Biomaterials and Biomolecular Systems, University of Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart, Germany
| | - Jürgen M Plitzko
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152, Martinsried, Germany
| | - Thomas P Burg
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany. .,Technische Universität Darmstadt, Merckstrasse 25, 64283, Darmstadt, Germany.
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9
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Pre-embedding labeling for subcellular detection of molecules with electron microscopy. Tissue Cell 2019; 57:103-110. [DOI: 10.1016/j.tice.2018.11.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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10
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Publisher Note. Tissue Cell 2018. [DOI: 10.1016/j.tice.2018.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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11
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Saarinen J, Gütter F, Lindman M, Agopov M, Fraser-Miller SJ, Scherließ R, Jokitalo E, Santos HA, Peltonen L, Isomäki A, Strachan CJ. Cell-Nanoparticle Interactions at (Sub)-Nanometer Resolution Analyzed by Electron Microscopy and Correlative Coherent Anti-Stokes Raman Scattering. Biotechnol J 2018; 14:e1800413. [PMID: 30350922 DOI: 10.1002/biot.201800413] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/25/2018] [Indexed: 01/15/2023]
Abstract
A wide variety of nanoparticles are playing an increasingly important role in drug delivery. Label-free imaging techniques are especially desirable to follow the cellular uptake and intracellular fate of nanoparticles. The combined correlative use of different techniques, each with unique advantages, facilitates more detailed investigation about such interactions. The synergistic use of correlative coherent anti-Stokes Raman scattering and electron microscopy (C-CARS-EM) imaging offers label-free, chemically-specific, and (sub)-nanometer spatial resolution for studying nanoparticle uptake into cells as demonstrated in the current study. Coherent anti-Stokes Raman scattering (CARS) microscopy offers chemically-specific (sub)micron spatial resolution imaging without fluorescent labels while transmission electron microscopy (TEM) offers (sub)-nanometer scale spatial resolution and thus visualization of precise nanoparticle localization at the sub-cellular level. This proof-of-concept imaging platform with unlabeled drug nanocrystals and macrophage cells revealed good colocalization between the CARS signal and electron dense nanocrystals in TEM images. The correlative TEM images revealed subcellular localization of nanocrystals inside membrane bound vesicles, showing multivesicular body (MVB)-like morphology typical for late endosomes (LEs), endolysosomes, and phagolysosomes. C-CARS-EM imaging has much potential to study the interactions between a wide range of nanoparticles and cells with high precision and confidence.
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Affiliation(s)
- Jukka Saarinen
- Drug Research Program, Division of Pharmaceutical Chemistry and , University of Helsinki, Viikinkaari 5 E (PO Box 56), 00014 Helsinki, Finland
| | - Friederike Gütter
- Pharmaceutical Institute Department of Pharmaceutics and Biopharmaceutics, Faculty of Mathematics and Natural Sciences, Kiel University, Grasweg 9a, 24118 Kiel, Germany
| | - Mervi Lindman
- Institute of Biotechnology, Electron Microscopy Unit, University of Helsinki, Viikinkaari 9 (PO Box 56), 00014 Helsinki, Finland
| | - Mikael Agopov
- Drug Research Program, Division of Pharmaceutical Chemistry and , University of Helsinki, Viikinkaari 5 E (PO Box 56), 00014 Helsinki, Finland
| | - Sara J Fraser-Miller
- Drug Research Program, Division of Pharmaceutical Chemistry and , University of Helsinki, Viikinkaari 5 E (PO Box 56), 00014 Helsinki, Finland.,Dodd-Walls Centre, Department of Chemistry, University of Otago, PO Box 56, 9056 Dunedin, New Zealand
| | - Regina Scherließ
- Pharmaceutical Institute Department of Pharmaceutics and Biopharmaceutics, Faculty of Mathematics and Natural Sciences, Kiel University, Grasweg 9a, 24118 Kiel, Germany
| | - Eija Jokitalo
- Institute of Biotechnology, Electron Microscopy Unit, University of Helsinki, Viikinkaari 9 (PO Box 56), 00014 Helsinki, Finland
| | - Hélder A Santos
- Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Viikinkaari 5 E (PO Box 56), 00014 Helsinki, Finland
| | - Leena Peltonen
- Drug Research Program, Division of Pharmaceutical Chemistry and , University of Helsinki, Viikinkaari 5 E (PO Box 56), 00014 Helsinki, Finland
| | - Antti Isomäki
- Biomedicum Imaging Unit, Faculty of Medicine, University of Helsinki, Haartmaninkatu 8 (PO Box 63), 00014 Helsinki, Finland
| | - Clare J Strachan
- Drug Research Program, Division of Pharmaceutical Chemistry and , University of Helsinki, Viikinkaari 5 E (PO Box 56), 00014 Helsinki, Finland
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12
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Santarella-Mellwig R, Haselmann U, Schieber NL, Walther P, Schwab Y, Antony C, Bartenschlager R, Romero-Brey I. Correlative Light Electron Microscopy (CLEM) for Tracking and Imaging Viral Protein Associated Structures in Cryo-immobilized Cells. J Vis Exp 2018. [PMID: 30247481 PMCID: PMC6235138 DOI: 10.3791/58154] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Due to its high resolution, electron microscopy (EM) is an indispensable tool for virologists. However, one of the main difficulties when analyzing virus-infected or transfected cells via EM are the low efficiencies of infection or transfection, hindering the examination of these cells. In order to overcome this difficulty, light microscopy (LM) can be performed first to allocate the subpopulation of infected or transfected cells. Thus, taking advantage of the use of fluorescent proteins (FPs) fused to viral proteins, LM is used here to record the positions of the "positive-transfected" cells, expressing a FP and growing on a support with an alphanumeric pattern. Subsequently, cells are further processed for EM via high pressure freezing (HPF), freeze substitution (FS) and resin embedding. The ultra-rapid freezing step ensures excellent membrane preservation of the selected cells that can then be analyzed at the ultrastructural level by transmission electron microscopy (TEM). Here, a step-by-step correlative light electron microscopy (CLEM) workflow is provided, describing sample preparation, imaging and correlation in detail. The experimental design can be also applied to address many cell biology questions.
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Affiliation(s)
| | - Uta Haselmann
- Department of Infectious Diseases, Molecular Virology, Heidelberg University
| | | | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University
| | | | | | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University; Heidelberg Partner Site, German Center for Infection Research;
| | - Inés Romero-Brey
- Department of Infectious Diseases, Molecular Virology, Heidelberg University;
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13
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Fuest M, Nocera GM, Modena MM, Riedel D, Mejia YX, Burg TP. Cryofixation during live-imaging enables millisecond time-correlated light and electron microscopy. J Microsc 2018; 272:87-95. [PMID: 30088278 DOI: 10.1111/jmi.12747] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/29/2018] [Accepted: 07/13/2018] [Indexed: 01/13/2023]
Abstract
Correlating live-cell imaging with electron microscopy is among the most promising approaches to relate dynamic functions of cells or small organisms to their underlying ultrastructure. The time correlation between light and electron micrographs, however, is limited by the sample handling and fixation required for electron microscopy. Current cryofixation methods require a sample transfer step from the light microscope to a dedicated instrument for cryofixation. This transfer step introduces a time lapse of one second or more between live imaging and the fixed state, which is studied by electron microscopy. In this work, we cryofix Caenorhabditis elegans directly within the light microscope field of view, enabling millisecond time-correlated live imaging and electron microscopy. With our approach, the time-correlation is limited only by the sample cooling rate. C. elegans was used as a model system to establish compatibility of in situ cryofixation and subsequent transmission electron microscopy (TEM). TEM images of in situ cryofixed C. elegans show that the ultrastructure of the sample was well preserved with this method. We expect that the ability to correlate live imaging and electron microscopy at the millisecond scale will enable new paradigms to study biological processes across length scales based on real-time selection and arrest of a desired state. LAY DESCRIPTION Researchers seek to link cellular functions to their smallest structural components. Currently this requires correlation of two imaging techniques, live imaging and electron microscopy. Current correlative methods, however, have limited time resolution due to the sample preparation procedures for electron microscopy. Following live imaging, samples are transferred from the light microscope to a cryofixation, or ultra-fast freezing, instrument. The biological process progresses until the sample freezes, 1 second or more after the last live image. In this work, samples are cryofixed directly within the light microscope field of view. By eliminating the transfer step, time correlation between light and electron microscopy images of our samples is limited only by the freezing rate to the order of milliseconds rather than seconds.
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Affiliation(s)
- M Fuest
- Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - G M Nocera
- Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - M M Modena
- Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - D Riedel
- Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - Y X Mejia
- Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
| | - T P Burg
- Max Planck Institute for Biophysical Chemistry, Goettingen, Germany
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14
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Clarke NI, Royle SJ. FerriTag is a new genetically-encoded inducible tag for correlative light-electron microscopy. Nat Commun 2018; 9:2604. [PMID: 29973588 PMCID: PMC6031641 DOI: 10.1038/s41467-018-04993-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 05/24/2018] [Indexed: 01/20/2023] Open
Abstract
A current challenge is to develop tags to precisely visualize proteins in cells by light and electron microscopy. Here, we introduce FerriTag, a genetically-encoded chemically-inducible tag for correlative light-electron microscopy. FerriTag is a fluorescent recombinant electron-dense ferritin particle that can be attached to a protein-of-interest using rapamycin-induced heterodimerization. We demonstrate the utility of FerriTag for correlative light-electron microscopy by labeling proteins associated with various intracellular structures including mitochondria, plasma membrane, and clathrin-coated pits and vesicles. FerriTagging has a good signal-to-noise ratio and a labeling resolution of approximately 10 nm. We demonstrate how FerriTagging allows nanoscale mapping of protein location relative to a subcellular structure, and use it to detail the distribution and conformation of huntingtin-interacting protein 1 related (HIP1R) in and around clathrin-coated pits.
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Affiliation(s)
- Nicholas I Clarke
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Stephen J Royle
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Gibbet Hill Road, Coventry, CV4 7AL, UK.
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15
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Tsang TK, Bushong EA, Boassa D, Hu J, Romoli B, Phan S, Dulcis D, Su CY, Ellisman MH. High-quality ultrastructural preservation using cryofixation for 3D electron microscopy of genetically labeled tissues. eLife 2018; 7:35524. [PMID: 29749931 PMCID: PMC5988420 DOI: 10.7554/elife.35524] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/09/2018] [Indexed: 02/06/2023] Open
Abstract
Electron microscopy (EM) offers unparalleled power to study cell substructures at the nanoscale. Cryofixation by high-pressure freezing offers optimal morphological preservation, as it captures cellular structures instantaneously in their near-native state. However, the applicability of cryofixation is limited by its incompatibility with diaminobenzidine labeling using genetic EM tags and the high-contrast en bloc staining required for serial block-face scanning electron microscopy (SBEM). In addition, it is challenging to perform correlated light and electron microscopy (CLEM) with cryofixed samples. Consequently, these powerful methods cannot be applied to address questions requiring optimal morphological preservation. Here, we developed an approach that overcomes these limitations; it enables genetically labeled, cryofixed samples to be characterized with SBEM and 3D CLEM. Our approach is broadly applicable, as demonstrated in cultured cells, Drosophila olfactory organ and mouse brain. This optimization exploits the potential of cryofixation, allowing for quality ultrastructural preservation for diverse EM applications.
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Affiliation(s)
- Tin Ki Tsang
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Eric A Bushong
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Daniela Boassa
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Junru Hu
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Benedetto Romoli
- Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla, United States
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States
| | - Davide Dulcis
- Department of Psychiatry, School of Medicine, University of California, San Diego, La Jolla, United States
| | - Chih-Ying Su
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California, San Diego, La Jolla, United States.,Department of Neurosciences, School of Medicine, University of California, San Diego, La Jolla, United States
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16
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Inducing fluorescence of uranyl acetate as a dual-purpose contrast agent for correlative light-electron microscopy with nanometre precision. Sci Rep 2017; 7:10442. [PMID: 28874723 PMCID: PMC5585351 DOI: 10.1038/s41598-017-10905-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 08/16/2017] [Indexed: 01/24/2023] Open
Abstract
Correlative light-electron microscopy (CLEM) combines the high spatial resolution of transmission electron microscopy (TEM) with the capability of fluorescence light microscopy (FLM) to locate rare or transient cellular events within a large field of view. CLEM is therefore a powerful technique to study cellular processes. Aligning images derived from both imaging modalities is a prerequisite to correlate the two microscopy data sets, and poor alignment can limit interpretability of the data. Here, we describe how uranyl acetate, a commonly-used contrast agent for TEM, can be induced to fluoresce brightly at cryogenic temperatures (−195 °C) and imaged by cryoFLM using standard filter sets. This dual-purpose contrast agent can be used as a general tool for CLEM, whereby the equivalent staining allows direct correlation between fluorescence and TEM images. We demonstrate the potential of this approach by performing multi-colour CLEM of cells containing equine arteritis virus proteins tagged with either green- or red-fluorescent protein, and achieve high-precision localization of virus-induced intracellular membrane modifications. Using uranyl acetate as a dual-purpose contrast agent, we achieve an image alignment precision of ~30 nm, twice as accurate as when using fiducial beads, which will be essential for combining TEM with the evolving field of super-resolution light microscopy.
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17
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Marion J, Le Bars R, Satiat-Jeunemaitre B, Boulogne C. Optimizing CLEM protocols for plants cells: GMA embedding and cryosections as alternatives for preservation of GFP fluorescence in Arabidopsis roots. J Struct Biol 2017; 198:196-202. [DOI: 10.1016/j.jsb.2017.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/23/2017] [Indexed: 12/21/2022]
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18
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Müller A, Neukam M, Ivanova A, Sönmez A, Münster C, Kretschmar S, Kalaidzidis Y, Kurth T, Verbavatz JM, Solimena M. A Global Approach for Quantitative Super Resolution and Electron Microscopy on Cryo and Epoxy Sections Using Self-labeling Protein Tags. Sci Rep 2017; 7:23. [PMID: 28154417 PMCID: PMC5428382 DOI: 10.1038/s41598-017-00033-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 12/20/2016] [Indexed: 01/19/2023] Open
Abstract
Correlative light and electron microscopy (CLEM) is a powerful approach to investigate the molecular ultrastructure of labeled cell compartments. However, quantitative CLEM studies are rare, mainly due to small sample sizes and the sensitivity of fluorescent proteins to strong fixatives and contrasting reagents for EM. Here, we show that fusion of a self-labeling protein to insulin allows for the quantification of age-distinct insulin granule pools in pancreatic beta cells by a combination of super resolution and transmission electron microscopy on Tokuyasu cryosections. In contrast to fluorescent proteins like GFP organic dyes covalently bound to self-labeling proteins retain their fluorescence also in epoxy resin following high pressure freezing and freeze substitution, or remarkably even after strong chemical fixation. This enables for the assessment of age-defined granule morphology and degradation. Finally, we demonstrate that this CLEM protocol is highly versatile, being suitable for single and dual fluorescent labeling and detection of different proteins with optimal ultrastructure preservation and contrast.
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Affiliation(s)
- Andreas Müller
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany.,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany
| | - Martin Neukam
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany.,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany
| | - Anna Ivanova
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany.,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany
| | - Anke Sönmez
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany.,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany
| | - Carla Münster
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany.,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany
| | - Susanne Kretschmar
- Center for Regenerative Therapies Dresden (CRTD), TU Dresden, Dresden, Germany.,Biotechnology Center of the TU Dresden (BIOTEC), Dresden, Germany
| | - Yannis Kalaidzidis
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany.,Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
| | - Thomas Kurth
- Center for Regenerative Therapies Dresden (CRTD), TU Dresden, Dresden, Germany.,Biotechnology Center of the TU Dresden (BIOTEC), Dresden, Germany
| | - Jean-Marc Verbavatz
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany.,Institut Jacques Monod, Université Paris Diderot, Paris, France
| | - Michele Solimena
- Molecular Diabetology, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany. .,Paul Langerhans Institute Dresden (PLID) of the Helmholtz Center Munich at the University Hospital Carl Gustav Carus and Faculty of Medicine of the TU Dresden, Dresden, Germany. .,Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Dresden, Germany.
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19
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Vancová M, Nebesářová J. Correlative Fluorescence and Scanning Electron Microscopy of Labelled Core Fucosylated Glycans Using Cryosections Mounted on Carbon-Patterned Glass Slides. PLoS One 2015; 10:e0145034. [PMID: 26690057 PMCID: PMC4699470 DOI: 10.1371/journal.pone.0145034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 11/30/2015] [Indexed: 01/05/2023] Open
Abstract
The aim of the study is co-localization of N-glycans with fucose attached to N-acetylglucosamine in α1,3 linkage, that belong to immunogenic carbohydrate epitopes in humans, and N-glycans with α1,6-core fucose typical for mammalian type of N-linked glycosylation. Both glycan epitopes were labelled in cryosections of salivary glands isolated from the tick Ixodes ricinus. Salivary glands secrete during feeding many bioactive molecules and influence both successful feeding and transmission of tick-borne pathogens. For accurate and reliable localization of labelled glycans in both fluorescence and scanning electron microscopes, we used carbon imprints of finder or indexed EM grids on glass slides. We discuss if the topographical images can provide information about labelled structures, the working setting of the field-emission scanning electron microscope and the influence of the detector selection (a below-the-lens Autrata improved YAG detector of back-scattered electrons; in-lens and conventional Everhart-Thornley detectors of secondary electrons) on the imaging of gold nanoparticles, quantum dots and osmium-stained membranes.
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Affiliation(s)
- Marie Vancová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, v.v.i, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- * E-mail:
| | - Jana Nebesářová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, v.v.i, České Budějovice, Czech Republic
- Faculty of Science, Charles University in Prague, Prague, Czech Republic
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20
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Visualization of adherent cell monolayers by cryo-electron microscopy: A snapshot of endothelial adherens junctions. J Struct Biol 2015; 192:470-477. [DOI: 10.1016/j.jsb.2015.10.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 10/08/2015] [Accepted: 10/09/2015] [Indexed: 01/05/2023]
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21
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Kourtesis I, Kasparov S, Verkade P, Teschemacher AG. Ultrastructural Correlates of Enhanced Norepinephrine and Neuropeptide Y Cotransmission in the Spontaneously Hypertensive Rat Brain. ASN Neuro 2015; 7:7/5/1759091415610115. [PMID: 26514659 PMCID: PMC4641560 DOI: 10.1177/1759091415610115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The spontaneously hypertensive rat (SHR) replicates many clinically relevant features of human essential hypertension and also exhibits behavioral symptoms of attention-deficit/hyperactivity disorder and dementia. The SHR phenotype is highly complex and cannot be explained by a single genetic or physiological mechanism. Nevertheless, numerous studies including our own work have revealed striking differences in central catecholaminergic transmission in SHR such as increased vesicular catecholamine content in the ventral brainstem. Here, we used immunolabeling followed by confocal microscopy and electron microscopy to quantify vesicle sizes and populations across three catecholaminergic brain areas—nucleus tractus solitarius and rostral ventrolateral medulla, both key regions for cardiovascular control, and the locus coeruleus. We also studied colocalization of neuropeptide Y (NPY) in norepinephrine and epinephrine-containing neurons as NPY is a common cotransmitter with central and peripheral catecholamines. We found significantly increased expression and coexpression of NPY in norepinephrine and epinephrine-positive neurons of locus coeruleus in SHR compared with Wistar rats. Ultrastructural analysis revealed immunolabeled vesicles of 150 to 650 nm in diameter (means ranging from 250 to 300 nm), which is much larger than previously reported. In locus coeruleus and rostral ventrolateral medulla, but not in nucleus tractus solitarius, of SHR, noradrenergic and adrenergic vesicles were significantly larger and showed increased NPY colocalization when compared with Wistar rats. Our morphological evidence underpins the hypothesis of hyperactivity of the noradrenergic and adrenergic system and increased norepinephrine and epinephrine and NPY cotransmission in specific brain areas in SHR. It further strengthens the argument for a prohypertensive role of C1 neurons in the rostral ventrolateral medulla as a potential causative factor for essential hypertension.
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Affiliation(s)
- Ioannis Kourtesis
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK Sars International Centre for Marine Molecular Biology, University of Bergen, Norway
| | - Sergey Kasparov
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK
| | - Paul Verkade
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK School of Biochemistry, University of Bristol, UK Wolfson Bioimaging Facility, University of Bristol, UK
| | - Anja G Teschemacher
- School of Physiology & Pharmacology, University of Bristol, UK Bristol Heart Institute, University of Bristol, UK
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22
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Nikolova LS, Metzstein MM. Intracellular lumen formation in Drosophila proceeds via a novel subcellular compartment. Development 2015; 142:3964-73. [PMID: 26428009 DOI: 10.1242/dev.127902] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 09/17/2015] [Indexed: 12/28/2022]
Abstract
Cellular tubes have diverse morphologies, including multicellular, unicellular and subcellular architectures. Subcellular tubes are found prominently within the vertebrate vasculature, the insect breathing system and the nematode excretory apparatus, but how such tubes form is poorly understood. To characterize the cellular mechanisms of subcellular tube formation, we have refined methods of high pressure freezing/freeze substitution to prepare Drosophila larvae for transmission electron microscopic (TEM) analysis. Using our methods, we have found that subcellular tube formation may proceed through a previously undescribed multimembrane intermediate composed of vesicles bound within a novel subcellular compartment. We have also developed correlative light/TEM procedures to identify labeled cells in TEM-fixed larval samples. Using this technique, we have found that Vacuolar ATPase (V-ATPase) and the V-ATPase regulator Rabconnectin-3 are required for subcellular tube formation, probably in a step resolving the intermediate compartment into a mature lumen. In general, our ultrastructural analysis methods could be useful for a wide range of cellular investigations in Drosophila larvae.
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Affiliation(s)
- Linda S Nikolova
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
| | - Mark M Metzstein
- Department of Human Genetics, University of Utah, Salt Lake City, UT 84112, USA
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23
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Smith SE, White RA, Grant DA, Grant SA. Fluorescence imaging preparation methods for tissue scaffolds implanted into a green fluorescent protein porcine model. Transgenic Res 2015; 24:911-9. [PMID: 26109094 DOI: 10.1007/s11248-015-9891-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 06/19/2015] [Indexed: 11/29/2022]
Abstract
Green fluorescent protein (GFP) animal models have become increasingly popular due to their potential to enhance in vivo imaging and their application to many fields of study. We have developed a technique to observe host tissue integration into scaffolds using GFP expressing swine and fluorescence imaging. Current fluorescence imaging preparation methods cannot be translated to a full GFP animal model due to several challenges and limitations that are investigated here. We have implanted tissue scaffolds into GFP expressing swine and have prepared explanted scaffolds for fluorescence imaging using four different methods including formalin fixation and paraffin embedding, vapor fixation, freshly prepared paraformaldehyde fixation, and fresh frozen tissue. Explanted scaffolds and tissue were imaged using confocal microscopy with spectral separation to evaluate the GFP animal model for visualization of host tissue integration into explanted scaffolds. All methods except fresh frozen tissue induced autofluorescence of the scaffold, preventing visualization of detail between host tissue and scaffold fibers. Fresh frozen tissue preparation allowed for the most reliable visualization of fluorescent host tissue integration into non-fluorescent scaffolds. It was concluded that fresh frozen tissue preparation is the best method for fluorescence imaging preparation when using scaffolds implanted into GFP whole animal models.
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Affiliation(s)
- Sarah E Smith
- Department of Bioengineering, University of Missouri, 250 Agricultural Engineering Building, Columbia, MO, 65211, USA
| | - Richard A White
- Department of Bioengineering, University of Missouri, 250 Agricultural Engineering Building, Columbia, MO, 65211, USA.,Department of Orthopaedic Surgery, University of Missouri, Columbia, MO, 65212, USA
| | - David A Grant
- Department of Bioengineering, University of Missouri, 250 Agricultural Engineering Building, Columbia, MO, 65211, USA
| | - Sheila A Grant
- Department of Bioengineering, University of Missouri, 250 Agricultural Engineering Building, Columbia, MO, 65211, USA.
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24
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Lobo J, See EYS, Biggs M, Pandit A. An insight into morphometric descriptors of cell shape that pertain to regenerative medicine. J Tissue Eng Regen Med 2015; 10:539-53. [DOI: 10.1002/term.1994] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 08/25/2014] [Accepted: 12/09/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Joana Lobo
- Network of Excellence for Functional Biomaterials (NFB); National University of Ireland; Galway Ireland
| | - Eugene Yong-Shun See
- Network of Excellence for Functional Biomaterials (NFB); National University of Ireland; Galway Ireland
| | - Manus Biggs
- Network of Excellence for Functional Biomaterials (NFB); National University of Ireland; Galway Ireland
| | - Abhay Pandit
- Network of Excellence for Functional Biomaterials (NFB); National University of Ireland; Galway Ireland
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25
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Kremer A, Lippens S, Bartunkova S, Asselbergh B, Blanpain C, Fendrych M, Goossens A, Holt M, Janssens S, Krols M, Larsimont JC, Mc Guire C, Nowack MK, Saelens X, Schertel A, Schepens B, Slezak M, Timmerman V, Theunis C, VAN Brempt R, Visser Y, Guérin CJ. Developing 3D SEM in a broad biological context. J Microsc 2015; 259:80-96. [PMID: 25623622 PMCID: PMC4670703 DOI: 10.1111/jmi.12211] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 11/28/2014] [Indexed: 12/25/2022]
Abstract
When electron microscopy (EM) was introduced in the 1930s it gave scientists their first look into the nanoworld of cells. Over the last 80 years EM has vastly increased our understanding of the complex cellular structures that underlie the diverse functions that cells need to maintain life. One drawback that has been difficult to overcome was the inherent lack of volume information, mainly due to the limit on the thickness of sections that could be viewed in a transmission electron microscope (TEM). For many years scientists struggled to achieve three-dimensional (3D) EM using serial section reconstructions, TEM tomography, and scanning EM (SEM) techniques such as freeze-fracture. Although each technique yielded some special information, they required a significant amount of time and specialist expertise to obtain even a very small 3D EM dataset. Almost 20 years ago scientists began to exploit SEMs to image blocks of embedded tissues and perform serial sectioning of these tissues inside the SEM chamber. Using first focused ion beams (FIB) and subsequently robotic ultramicrotomes (serial block-face, SBF-SEM) microscopists were able to collect large volumes of 3D EM information at resolutions that could address many important biological questions, and do so in an efficient manner. We present here some examples of 3D EM taken from the many diverse specimens that have been imaged in our core facility. We propose that the next major step forward will be to efficiently correlate functional information obtained using light microscopy (LM) with 3D EM datasets to more completely investigate the important links between cell structures and their functions.
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Affiliation(s)
- A Kremer
- VIB Bio Imaging Core, Gent, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - S Lippens
- VIB Bio Imaging Core, Gent, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - S Bartunkova
- VIB Bio Imaging Core, Gent, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - B Asselbergh
- VIB Department of Molecular Genetics, Antwerp University, Antwerpen 2020, Belgium
| | - C Blanpain
- IRIBHM, Université Libre de Bruxelles, Brussels, B-1070, Belgium
| | - M Fendrych
- Department of Plant Systems Biology, VIB, Ghent, 9052, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.,Institute of Science and Technology (IST) Austria, Klosterneuburg, 3400, Austria
| | - A Goossens
- Department of Plant Systems Biology, VIB, Ghent, 9052, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium
| | - M Holt
- Center for the Biology of Disease, VIB, Leuven, Belgium.,Institute for Biology/Genetics, Freie Universität Berlin, Berlin, Germany
| | - S Janssens
- Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Respiratory Medicine, Ghent University, Ghent, Belgium.,GROUP-ID Consortium, Ghent University and University Hospital, Ghent, Belgium
| | - M Krols
- Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,VIB Department of Molecular Genetics, Antwerp University, Antwerpen 2020, Belgium
| | - J-C Larsimont
- IRIBHM, Université Libre de Bruxelles, Brussels, B-1070, Belgium
| | - C Mc Guire
- Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - M K Nowack
- Department of Plant Systems Biology, VIB, Ghent, 9052, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium
| | - X Saelens
- Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - A Schertel
- Carl Zeiss Microscopy, GmbH, Oberkochen, Germany
| | - B Schepens
- Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - M Slezak
- Center for the Biology of Disease, VIB, Leuven, Belgium
| | - V Timmerman
- VIB Department of Molecular Genetics, Antwerp University, Antwerpen 2020, Belgium
| | - C Theunis
- Department of Intensive Care, Leiden University Medical Center, Leiden, The Netherlands.,Johnson and Johnson Pharmaceutical Research and Development, Beerse, Belgium
| | - R VAN Brempt
- Department of Intensive Care, Leiden University Medical Center, Leiden, The Netherlands.,Johnson and Johnson Pharmaceutical Research and Development, Beerse, Belgium
| | - Y Visser
- Department of Intensive Care, Leiden University Medical Center, Leiden, The Netherlands.,Johnson and Johnson Pharmaceutical Research and Development, Beerse, Belgium
| | - C J Guérin
- VIB Bio Imaging Core, Gent, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Inflammation Research Center, VIB, Technologiepark 927, Gent, B-9052, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
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The Use of a Green Fluorescent Protein Porcine Model to Evaluate Host Tissue Integration into Extracellular Matrix Derived Bionanocomposite Scaffolds. ACTA ACUST UNITED AC 2015. [DOI: 10.1155/2015/586493] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
When using heterogeneous extracellular matrix (ECM) derived scaffolds for soft tissue repair, current methods of in vivo evaluation can fail to provide a clear distinction between host collagen and implanted scaffolds making it difficult to assess host tissue integration and remodeling. The purpose of this study is both to evaluate novel scaffolds conjugated with nanoparticles for host tissue integration and biocompatibility and to assess green fluorescent protein (GFP) expressing swine as a new animal model to evaluate soft tissue repair materials. Human-derived graft materials conjugated with nanoparticles were subcutaneously implanted into GFP expressing swine to be evaluated for biocompatibility and tissue integration through histological scoring and confocal imaging. Histological scoring indicates biocompatibility and remodeling of the scaffolds with and without nanoparticles at 1, 3, and 6 months. Confocal microscope images display host tissue integration into scaffolds although nonspecificity of GFP does not allow for quantification of integration. However, the confocal images do allow for spatial observation of host tissue migration into the scaffolds at different depths of penetration. The study concludes that the nanoparticle scaffolds are biocompatible and promote integration and that the use of GFP expressing swine can aid in visualizing the scaffold/host interface and host cell/tissue migration.
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Mari M, Geerts WJ, Reggiori F. Immuno- and Correlative Light Microscopy-Electron Tomography Methods for 3D Protein Localization in Yeast. Traffic 2014; 15:1164-78. [DOI: 10.1111/tra.12192] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/16/2014] [Accepted: 07/01/2014] [Indexed: 01/03/2023]
Affiliation(s)
- Muriel Mari
- Department of Cell Biology, Institute for Molecular Medicine; University Medical Centre Utrecht; Heidelberglaan 100 3584 CX Utrecht The Netherlands
| | - Willie J.C. Geerts
- Bijvoet Center, Faculty of Science; Utrecht University; Padualaan 8 3584 CH Utrecht The Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology, Institute for Molecular Medicine; University Medical Centre Utrecht; Heidelberglaan 100 3584 CX Utrecht The Netherlands
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28
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Duke EMH, Razi M, Weston A, Guttmann P, Werner S, Henzler K, Schneider G, Tooze SA, Collinson LM. Imaging endosomes and autophagosomes in whole mammalian cells using correlative cryo-fluorescence and cryo-soft X-ray microscopy (cryo-CLXM). Ultramicroscopy 2014; 143:77-87. [PMID: 24238600 PMCID: PMC4045213 DOI: 10.1016/j.ultramic.2013.10.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/01/2013] [Accepted: 10/07/2013] [Indexed: 12/20/2022]
Abstract
Cryo-soft X-ray tomography (cryo-SXT) is a powerful imaging technique that can extract ultrastructural information from whole, unstained mammalian cells as close to the living state as possible. Subcellular organelles including the nucleus, the Golgi apparatus and mitochondria have been identified by morphology alone, due to the similarity in contrast to transmission electron micrographs. In this study, we used cryo-SXT to image endosomes and autophagosomes, organelles that are particularly susceptible to chemical fixation artefacts during sample preparation for electron microscopy. We used two approaches to identify these compartments. For early and recycling endosomes, which are accessible to externally-loaded markers, we used an anti-transferrin receptor antibody conjugated to 10nm gold particles. For autophagosomes, which are not accessible to externally-applied markers, we developed a correlative cryo-fluorescence and cryo-SXT workflow (cryo-CLXM) to localise GFP-LC3 and RFP-Atg9. We used a stand-alone cryo-fluorescence stage in the home laboratory to localise the cloned fluorophores, followed by cryo-soft X-ray tomography at the synchrotron to analyse cellular ultrastructure. We mapped the 3D ultrastructure of the endocytic and autophagic structures, and discovered clusters of omegasomes arising from 'hotspots' on the ER. Thus, immunogold markers and cryo-CLXM can be used to analyse cellular processes that are inaccessible using other imaging modalities.
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Affiliation(s)
- Elizabeth M H Duke
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Minoo Razi
- Secretory Pathways Laboratory, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Anne Weston
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Peter Guttmann
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Soft Matter and Functional Materials, 12489 Berlin, Germany
| | - Stephan Werner
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Soft Matter and Functional Materials, 12489 Berlin, Germany
| | - Katja Henzler
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Soft Matter and Functional Materials, 12489 Berlin, Germany
| | - Gerd Schneider
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institute for Soft Matter and Functional Materials, 12489 Berlin, Germany
| | - Sharon A Tooze
- Secretory Pathways Laboratory, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Lucy M Collinson
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK.
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29
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Peddie CJ, Blight K, Wilson E, Melia C, Marrison J, Carzaniga R, Domart MC, O'Toole P, Larijani B, Collinson LM. Correlative and integrated light and electron microscopy of in-resin GFP fluorescence, used to localise diacylglycerol in mammalian cells. Ultramicroscopy 2014; 143:3-14. [PMID: 24637200 PMCID: PMC4045205 DOI: 10.1016/j.ultramic.2014.02.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/10/2014] [Accepted: 02/12/2014] [Indexed: 12/11/2022]
Abstract
Fluorescence microscopy of GFP-tagged proteins is a fundamental tool in cell biology, but without seeing the structure of the surrounding cellular space, functional information can be lost. Here we present a protocol that preserves GFP and mCherry fluorescence in mammalian cells embedded in resin with electron contrast to reveal cellular ultrastructure. Ultrathin in-resin fluorescence (IRF) sections were imaged simultaneously for fluorescence and electron signals in an integrated light and scanning electron microscope. We show, for the first time, that GFP is stable and active in resin sections in vacuo. We applied our protocol to study the subcellular localisation of diacylglycerol (DAG), a modulator of membrane morphology and membrane dynamics in nuclear envelope assembly. We show that DAG is localised to the nuclear envelope, nucleoplasmic reticulum and curved tips of the Golgi apparatus. With these developments, we demonstrate that integrated imaging is maturing into a powerful tool for accurate molecular localisation to structure.
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Affiliation(s)
- Christopher J Peddie
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Ken Blight
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Emma Wilson
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Charlotte Melia
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK; Cell Biophysics Laboratory, London Research Institute, Cancer Research UK, London WC2A 3LY, UK; Department of Molecular Cell Biology, Leiden University Medical Centre, 2300 RC Leiden, The Netherlands
| | - Jo Marrison
- Department of Biology, The University of York, Heslington, York, UK
| | - Raffaella Carzaniga
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Marie-Charlotte Domart
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK; Cell Biophysics Laboratory, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
| | - Peter O'Toole
- Department of Biology, The University of York, Heslington, York, UK
| | - Banafshe Larijani
- Cell Biophysics Laboratory, London Research Institute, Cancer Research UK, London WC2A 3LY, UK; Cell Biophysics Laboratory, Unidad de Biofísica (CSIC-UPV/EHU),Sarriena s/n, 48940 Leioa, Spain; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Lucy M Collinson
- Electron Microscopy Unit, London Research Institute, Cancer Research UK, London WC2A 3LY, UK
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30
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MAVIS: An integrated system for live microscopy and vitrification. Ultramicroscopy 2014; 143:67-76. [DOI: 10.1016/j.ultramic.2013.10.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/04/2013] [Accepted: 10/08/2013] [Indexed: 11/24/2022]
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31
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Correlative video-light–electron microscopy: development, impact and perspectives. Histochem Cell Biol 2014; 142:133-8. [DOI: 10.1007/s00418-014-1249-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2014] [Indexed: 11/25/2022]
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32
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Bos E, Hussaarts L, van Weering JRT, Ellisman MH, de Wit H, Koster AJ. Vitrification of Tokuyasu-style immuno-labelled sections for correlative cryo light microscopy and cryo electron tomography. J Struct Biol 2014; 186:273-82. [PMID: 24704216 DOI: 10.1016/j.jsb.2014.03.021] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 03/24/2014] [Accepted: 03/25/2014] [Indexed: 10/25/2022]
Abstract
We present an approach for the preparation of immuno-labelled ultrathin sections from cells or tissue that are compatible with both fluorescence and transmission electron microscopy. Our approach is inspired by a method of Sabanay et al. (1991) that is based on the Tokuyasu technique for immunogold labelling of sections from aldehyde-fixed samples. The difference of this method with the original Tokuyasu technique is that the immuno-labelled sections are stabilized in a thin layer of vitreous water by plunge-freezing prior to electron microscopical observation. The vitrification step allows for phase contrast-based imaging at cryogenic conditions. We show that this immuno-labelling method is well-suited for imaging cellular ultrastructure in three dimensions (tomography) at cryogenic conditions, and that fluorescence associated with the sections is retained. This method is a valuable tool for Correlative Light and Electron Microscopy (CLEM), and we refer to this method in combination with CLEM as VOS (vitrification of sections). We provide examples for the application of VOS using dendritic cells and neurons, and show specifically that this method enables the researcher to navigate to lysosomes and synapses.
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Affiliation(s)
- Erik Bos
- Department of Molecular Cell Biology, Section Electron Microscopy, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands
| | - Leonie Hussaarts
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan R T van Weering
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University and VU Medical Center, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research (NCMIR), Department of Neurosciences, University of California San Diego, 9500 Gilman Drive MC0608, La Jolla, CA 92093-0608, United States
| | - Heidi de Wit
- Department of Functional Genomics and Clinical Genetics, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University and VU Medical Center, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Abraham J Koster
- Department of Molecular Cell Biology, Section Electron Microscopy, Leiden University Medical Center, P.O. Box 9600, 2300 RC, Leiden, The Netherlands.
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33
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Yuan Y, Li M, Hong N, Hong Y. Correlative light and electron microscopic analyses of mitochondrial distribution in blastomeres of early fish embryos. FASEB J 2014; 28:577-585. [DOI: 10.1096/fj.13-233635] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Affiliation(s)
- Yongming Yuan
- Department of Biological SciencesNational University of SingaporeSingaporeSingapore
| | - Mingyou Li
- Department of Biological SciencesNational University of SingaporeSingaporeSingapore
- College of Fisheries and Life ScienceShanghai Ocean UniversityShanghaiChina
| | - Ni Hong
- Department of Biological SciencesNational University of SingaporeSingaporeSingapore
| | - Yunhan Hong
- Department of Biological SciencesNational University of SingaporeSingaporeSingapore
- College of Fisheries and Life ScienceShanghai Ocean UniversityShanghaiChina
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34
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Madela K, Banhart S, Zimmermann A, Piesker J, Bannert N, Laue M. A simple procedure to analyze positions of interest in infectious cell cultures by correlative light and electron microscopy. Methods Cell Biol 2014; 124:93-110. [PMID: 25287838 DOI: 10.1016/b978-0-12-801075-4.00005-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Plastic cell culture dishes that contain a thin bottom of highest optical quality including an imprinted finder grid (μ-Dish Grid-500) are optimally suited for routine correlative light and electron microscopy using chemical fixation. Such dishes allow high-resolution fluorescence and bright-field imaging using fixed and living cells and are compatible with standard protocols for scanning and transmission electron microscopy. Ease of use during cell culture and imaging, as well as a tight cover render the dishes particularly suitable for working with infectious organisms up to the highest biosafety level. Detailed protocols are provided and demonstrated by showing two examples: monitoring the production of virus-like particles of the Human Endogenous Retrovirus HERV-K(HML-2) by HeLa cells and investigation of Rab11-positive membrane-compartments of HeLa cells after infection with Chlamydia trachomatis.
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Affiliation(s)
- Kazimierz Madela
- Advanced Light and Electron Microscopy (ZBS 4), Robert Koch Institute, Berlin, Germany
| | - Sebastian Banhart
- Junior Research Group Sexually Transmitted Bacterial Pathogens (NG 5), Robert Koch Institute, Berlin, Germany
| | - Anja Zimmermann
- Centre for HIV and other Retroviruses (FG 18), Robert Koch Institute, Berlin, Germany
| | - Janett Piesker
- Advanced Light and Electron Microscopy (ZBS 4), Robert Koch Institute, Berlin, Germany
| | - Norbert Bannert
- Centre for HIV and other Retroviruses (FG 18), Robert Koch Institute, Berlin, Germany
| | - Michael Laue
- Advanced Light and Electron Microscopy (ZBS 4), Robert Koch Institute, Berlin, Germany
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35
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Correlative Light Microscopy and Electron Tomography to Study Von Willebrand Factor Exocytosis from Vascular Endothelial Cells. Methods Cell Biol 2014; 124:71-92. [DOI: 10.1016/b978-0-12-801075-4.00004-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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36
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37
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Schell C, Baumhakl L, Salou S, Conzelmann AC, Meyer C, Helmstädter M, Wrede C, Grahammer F, Eimer S, Kerjaschki D, Walz G, Snapper S, Huber TB. N-wasp is required for stabilization of podocyte foot processes. J Am Soc Nephrol 2013; 24:713-21. [PMID: 23471198 DOI: 10.1681/asn.2012080844] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Alteration of cortical actin structures is the common final pathway leading to podocyte foot process effacement and proteinuria. The molecular mechanisms that safeguard podocyte foot process architecture and maintain the three-dimensional actin network remain elusive. Here, we demonstrate that neuronal Wiskott-Aldrich syndrome protein (N-WASP), which promotes actin nucleation, is required to stabilize podocyte foot processes. Mice lacking N-WASP specifically in podocytes were born with normal kidney function but developed significant proteinuria 3 weeks after birth, suggesting an important role for N-WASP in maintaining foot processes. In addition, inducing deletion of N-WASP in adult mice resulted in severe proteinuria and kidney failure. Electron microscopy showed an accumulation of electron-dense patches of actin and strikingly altered morphology of podocyte foot processes. Although basic actin-based processes such as cell migration were not affected, primary cultures of N-WASP-deficient podocytes revealed significant impairment of dynamic actin reorganization events, including the formation of circular dorsal ruffles. Taken together, our findings suggest that N-WASP-mediated actin nucleation of branched microfilament networks is specifically required for the maintenance of foot processes, presumably sustaining the mechanical resistance of the filtration barrier.
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Affiliation(s)
- Christoph Schell
- Renal Division, University Hospital Freiburg, Breisacher Str. 66, 79106 Freiburg, Germany
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38
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Polishchuk EV, Polishchuk RS, Luini A. Correlative light-electron microscopy as a tool to study in vivo dynamics and ultrastructure of intracellular structures. Methods Mol Biol 2013; 931:413-22. [PMID: 23027014 DOI: 10.1007/978-1-62703-056-4_20] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Correlative light-electron microscopy (CLEM) is a very effective technique that combines live-cell imaging and immuno-electron microscopy for ultrastructural morphological characterization of dynamic intracellular organelles. The use of green fluorescent protein (GFP)-tagged chimeras allows the user to follow the movements and/or behavior of intracellular structures in a live cell and to fix it at the moment of interest. The subsequent immuno-electron microscopy processing can then reveal the three-dimensional architecture of the same structure, together with precise recognition of the GFP-labeled protein. The process resembles the taking of a high-resolution snapshot of an interesting live scene. Considering that CLEM is a very useful but technically demanding and time-consuming technique, accurate protocols will be helpful to simplify the work of scientists who are willing to apply this method for their own purposes. Here, we present a detailed protocol that describes all of the "tricks" and know-hows involved in carrying out the crucial steps of a CLEM experiment.
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39
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Tanaka H, Miyazaki N, Matoba K, Nogi T, Iwasaki K, Takagi J. Higher-Order Architecture of Cell Adhesion Mediated by Polymorphic Synaptic Adhesion Molecules Neurexin and Neuroligin. Cell Rep 2012; 2:101-10. [DOI: 10.1016/j.celrep.2012.06.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 05/07/2012] [Accepted: 06/11/2012] [Indexed: 11/24/2022] Open
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40
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Kobayashi K, Cheng D, Huynh M, Ratinac KR, Thordarson P, Braet F. Imaging fluorescently labeled complexes by means of multidimensional correlative light and transmission electron microscopy: practical considerations. Methods Cell Biol 2012; 111:1-20. [PMID: 22857920 DOI: 10.1016/b978-0-12-416026-2.00001-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
These days the common ground between structural biology and molecular biology continues to grow thanks to the biomolecular insights offered by correlative microscopy, even though the vision of combining insights from different imaging tools has been around for nearly four decades. The use of correlative imaging methods to dissect the cell's internal structure is progressing faster than ever as shown by the boom in the number of methodological approaches available for correlative microscopy studies, each designed to address a specific scientific question. In this chapter, we will present a relatively straightforward approach to combining information from fluorescence microscopy and electron microscopy at the supramolecular level. The method combines live-cell and/or confocal laser microscopy with classical sample preparation for transmission electron microscopy (TEM), thereby allowing the integration of dynamic details of subcellular processes with insights about the organelles and molecular machinery involved. We illustrate the applicability of this multidimensional correlative microscopy approach on cultured Caco-2 colorectal cancer cells exposed to fluorescently labeled cisplatin, and discuss how these methods can deepen our understanding of key cellular processes, such as drug uptake and cell fate.
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Affiliation(s)
- K Kobayashi
- Australian Centre for Microscopy & Microanalysis, The University of Sydney, NSW 2006, Australia
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41
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Brown E, Van Weering J, Sharp T, Mantell J, Verkade P. Capturing endocytic segregation events with HPF-CLEM. Methods Cell Biol 2012; 111:175-201. [PMID: 22857929 DOI: 10.1016/b978-0-12-416026-2.00010-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We have advocated the use of high-pressure freezing (HPF) in specific types of Correlative Light Electron Microscopy (CLEM) experiments because the intracellular components such as the cytoskeleton and membrane tubules can only be adequately preserved via cryofixation. To allow fast transfer from the light microscope into a cryofixation device, we have developed the Rapid Transfer System (RTS) for the EMPACT2 high-pressure freezer. In this chapter, we will describe how to prepare and perform a CLEM experiment using this device and will highlight the latest changes made to the original system to optimize the workflow.
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Affiliation(s)
- Edward Brown
- Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol, BS8 1TD, UK
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42
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Fabig G, Kretschmar S, Weiche S, Eberle D, Ader M, Kurth T. Labeling of ultrathin resin sections for correlative light and electron microscopy. Methods Cell Biol 2012; 111:75-93. [PMID: 22857924 DOI: 10.1016/b978-0-12-416026-2.00005-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Correlative microscopy combines the versatility of the light microscope with the excellent spatial resolution of the electron microscope. Here, we describe fast and simple methods for correlative immunofluorescence and immunogold labeling on the very same ultrathin section. The protocols are demonstrated on sections of tissue samples embedded in the methacrylate Lowicryl K4M. Ultrathin sections are mounted on electron microscopy (EM) grids and stained simultaneously with fluorescent and gold markers. For the detection of primary antibodies, we applied either protein A gold or immunoglobulin G (IgG) gold in combination with secondary antibodies coupled to Alexa488 or Alexa555. Alternatively, the correlative marker FluoroNanogold was used, followed by silver enhancement. The samples have to be analyzed first at the light microscope and then in the transmission electron microscope (TEM), because the fluorescence is bleached by the electron beam. Labeled structures selected at the fluorescence microscope can be identified in the TEM and analyzed at high resolution. This way, fluorescent signals can be directly correlated to the corresponding subcellular structures in the area of interest.
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Affiliation(s)
- Gunar Fabig
- Center for Regenerative Therapies, TU Dresden, Fetscherstraße 105, D-01307 Dresden, Saxony, Germany
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43
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Meisslitzer-Ruppitsch C, Röhrl C, Ranftler C, Stangl H, Neumüller J, Pavelka M, Ellinger A. Photooxidation technology for correlative light and electron microscopy. Methods Mol Biol 2012; 931:423-36. [PMID: 23027015 DOI: 10.1007/978-1-62703-056-4_21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Correlative microscopic approaches combine the advantages of both light and electron microscopy. Here we show a correlative approach that uses the photooxidation capacity of fluorescent dyes. Through illumination with high energetic light, the chromogen diaminobenzidine is oxidized and stable deposits are formed at the sites of the former fluorescent signals, which after osmification are then visible in the electron microscope. The potential of the method is illustrated by tracing the endocytic pathway of three different ligands: the lipid ceramide, high density lipoproteins, and the lectin wheat germ agglutinin. The ligands were labeled either with BODIPY or Alexa dyes. Following cell surface binding, uptake, and time-dependent intracellular progression, the route taken by these molecules together with the organelles that have been visited is characterized. Correlative microscopic data are recorded at various levels. First, by fluorescence and phase contrast illumination with the light microscope, followed by the analysis of semithin sections after photooxidation, and finally of thin sections at the ultrastructural level.
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Affiliation(s)
- Claudia Meisslitzer-Ruppitsch
- Department of Cell Biology and Ultrastructure Research, Center for Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
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44
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Polishchuk RS, Polishchuk EV, Luini A. Visualizing live dynamics and ultrastructure of intracellular organelles with preembedding correlative light-electron microscopy. Methods Cell Biol 2012; 111:21-35. [PMID: 22857921 DOI: 10.1016/b978-0-12-416026-2.00002-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
One of the very effective methods to perform correlative light-electron microscopy (CLEM) is to combine video imaging of live cells with immuno-electron microscopy. This technique can thus provide detailed, high-resolution characterization of dynamic intracellular organelles. The use of green fluorescent protein (GFP)-tagged chimeras allows the movements and/or behavior of intracellular structures in a live cell to be followed, which can then be fixed at the moment of interest. The subsequent immuno-electron microscopy analysis reveals the three-dimensional (3D) architecture of the same structure, together with the precise identification of the GFP-labeled protein pattern. The process resembles taking a high-resolution snapshot of an interesting and/or rare live event. Conceptually, it consists of a switch of wavelengths, from that of photons to that of electrons, with the associated huge gain in resolution. In this respect, CLEM can be considered as the first, and probably one of the most powerful, super-resolution microscopy techniques. This switch, however, requires complex manipulations of the sample. Considering that CLEM is a very valuable but technically challenging and time-consuming method, accurate protocols are needed to simplify the efforts of researchers who are willing to apply this method for their own purposes. Here, we present a detailed description of the preembedding CLEM procedures that explains the know-how and the "tricks of the trade" that are involved in carrying out the crucial steps of CLEM.
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45
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Jahn KA, Barton DA, Kobayashi K, Ratinac KR, Overall RL, Braet F. Correlative microscopy: providing new understanding in the biomedical and plant sciences. Micron 2011; 43:565-82. [PMID: 22244153 DOI: 10.1016/j.micron.2011.12.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 12/14/2011] [Accepted: 12/14/2011] [Indexed: 12/16/2022]
Abstract
Correlative microscopy is the application of two or more distinct microscopy techniques to the same region of a sample, generating complementary morphological, structural and chemical information that exceeds what is possible with any single technique. As a variety of complementary microscopy approaches rather than a specific type of instrument, correlative microscopy has blossomed in recent years as researchers have recognised that it is particularly suited to address the intricate questions of the modern biological sciences. Specialised technical developments in sample preparation, imaging methods, visualisation and data analysis have also accelerated the uptake of correlative approaches. In light of these advances, this critical review takes the reader on a journey through recent developments in, and applications of, correlative microscopy, examining its impact in biomedical research and in the field of plant science. This twin emphasis gives a unique perspective into use of correlative microscopy in fields that often advance independently, and highlights the lessons that can be learned from both fields for the future of this important area of research.
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Affiliation(s)
- K A Jahn
- Australian Centre for Microscopy & Microanalysis and The School of Biological Sciences, The University of Sydney, Sydney, NSW 2006, Australia.
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Murphy GE, Narayan K, Lowekamp BC, Hartnell LM, Heymann JAW, Fu J, Subramaniam S. Correlative 3D imaging of whole mammalian cells with light and electron microscopy. J Struct Biol 2011; 176:268-78. [PMID: 21907806 PMCID: PMC3210386 DOI: 10.1016/j.jsb.2011.08.013] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 08/22/2011] [Accepted: 08/25/2011] [Indexed: 01/19/2023]
Abstract
We report methodological advances that extend the current capabilities of ion-abrasion scanning electron microscopy (IA-SEM), also known as focused ion beam scanning electron microscopy, a newly emerging technology for high resolution imaging of large biological specimens in 3D. We establish protocols that enable the routine generation of 3D image stacks of entire plastic-embedded mammalian cells by IA-SEM at resolutions of ∼10-20nm at high contrast and with minimal artifacts from the focused ion beam. We build on these advances by describing a detailed approach for carrying out correlative live confocal microscopy and IA-SEM on the same cells. Finally, we demonstrate that by combining correlative imaging with newly developed tools for automated image processing, small 100nm-sized entities such as HIV-1 or gold beads can be localized in SEM image stacks of whole mammalian cells. We anticipate that these methods will add to the arsenal of tools available for investigating mechanisms underlying host-pathogen interactions, and more generally, the 3D subcellular architecture of mammalian cells and tissues.
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Affiliation(s)
- Gavin E. Murphy
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892 USA
| | - Kedar Narayan
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892 USA
| | - Bradley C. Lowekamp
- Office of High Performance Computing and Communications, National Library of Medicine, NIH, Bethesda, MD 20814 USA
| | - Lisa M. Hartnell
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892 USA
| | - Jurgen A. W. Heymann
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892 USA
| | - Jing Fu
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892 USA
| | - Sriram Subramaniam
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892 USA
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Caplan J, Niethammer M, Taylor RM, Czymmek KJ. The power of correlative microscopy: multi-modal, multi-scale, multi-dimensional. Curr Opin Struct Biol 2011; 21:686-93. [PMID: 21782417 DOI: 10.1016/j.sbi.2011.06.010] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 06/22/2011] [Indexed: 11/24/2022]
Abstract
Correlative microscopy is a sophisticated approach that combines the capabilities of typically separate, but powerful microscopy platforms: often including, but not limited, to conventional light, confocal and super-resolution microscopy, atomic force microscopy, transmission and scanning electron microscopy, magnetic resonance imaging and micro/nano CT (computed tomography). When targeting rare or specific events within large populations or tissues, correlative microscopy is increasingly being recognized as the method of choice. Furthermore, this multi-modal assimilation of technologies provides complementary and often unique information, such as internal and external spatial, structural, biochemical and biophysical details from the same targeted sample. The development of a continuous stream of cutting-edge applications, probes, preparation methodologies, hardware and software developments will enable realization of the full potential of correlative microscopy.
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Affiliation(s)
- Jeffrey Caplan
- Delaware Biotechnology Institute Bio-Imaging Center, University of Delaware, Newark, DE 19711, United States
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Imaging three-dimensional tissue architectures by focused ion beam scanning electron microscopy. Nat Protoc 2011; 6:845-58. [DOI: 10.1038/nprot.2011.332] [Citation(s) in RCA: 121] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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The ceramide-enriched trans-Golgi compartments reorganize together with other parts of the Golgi apparatus in response to ATP-depletion. Histochem Cell Biol 2011; 135:159-71. [PMID: 21225431 DOI: 10.1007/s00418-010-0773-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2010] [Indexed: 12/22/2022]
Abstract
In this study, the ceramide-enriched trans-Golgi compartments representing sites of synthesis of sphingomyelin and higher organized lipids were visualized in control and ATP-depleted hepatoma and endothelial cells using internalization of BODIPY-ceramide and the diaminobenzidine photooxidation method for combined light-electron microscopical exploration. Metabolic stress induced by lowering the cellular ATP-levels leads to reorganizations of the Golgi apparatus and the appearance of tubulo-glomerular bodies and networks. The results obtained with three different protocols, in which BODIPY-ceramide either was applied prior to, concomitantly with, or after ATP-depletion, revealed that the ceramide-enriched compartments reorganize together with other parts of the Golgi apparatus under these conditions. They were found closely associated with and integrated in the tubulo-glomerular bodies formed in response to ATP-depletion. This is in line with the changes of the staining patterns obtained with the Helix pomatia lectin and the GM130 and TGN46 immuno-reactions occurring in response to ATP-depletion and is confirmed by 3D electron tomography. The 3D reconstructions underlined the glomerular character of the reorganized Golgi apparatus and demonstrated continuities of ceramide positive and negative parts. Most interestingly, BODIPY-ceramide becomes concentrated in compartments of the tubulo-glomerular Golgi bodies, even though the reorganization took place before BODIPY-ceramide administration. This indicates maintained functionalities although the regular Golgi stack organization is abolished; the results provide novel insights into Golgi structure-function relationships, which might be relevant for cells affected by metabolic stress.
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Abstract
The myelin sheath is an essential component of the vertebrate nervous system, and its disruption causes numerous diseases, including multiple sclerosis (MS), and neurodegeneration. Although we understand a great deal about the early development of the glial cells that make myelin (Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system), we know much less about the cellular and molecular mechanisms that regulate the later stages of differentiation that orchestrate myelin formation. Over the past decade, the zebrafish has been employed as a model with which to dissect the development of myelinated axons. Forward genetic screens have revealed new genes essential for myelination, as well as new roles for genes previously implicated in myelinated axon formation in other systems. High-resolution in vivo imaging in zebrafish has also begun to illuminate novel cell behaviors during myelinating glial cell development. Here we review the contribution of zebrafish research to our understanding of myelinated axon formation to date. We also describe and discuss many of the methodologies used in these studies and preview future endeavors that will ensure that the zebrafish remains at the cutting edge of this important area of research.
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Affiliation(s)
- Tim Czopka
- Centre for Neuroregeneration, University of Edinburgh, Chancellor's Building, 49 Little France Crescent, Edinburgh, UK
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