1
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Scharrig E, Sanmillan ML, Giraudo CG. Analysis of immune synapses by τau-STED imaging and 3D-quantitative colocalization of lytic granule markers. Methods Cell Biol 2023. [DOI: 10.1016/bs.mcb.2023.01.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
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2
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Pu R, Liu S, Wang B, Zhan Q. Photoswitching the injected energy flux via core-sensitized energy migration upconversion for emission-varying STED microscopy. OPTICS LETTERS 2022; 47:4746-4749. [PMID: 36107080 DOI: 10.1364/ol.464515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
Stimulated emission depletion (STED) microscopy achieved with lanthanide-doped upconversion nanoparticles (UCNPs) exhibits many outstanding advantages such as low-power illumination, near-infrared (NIR) excitation, and high photostability. However, the available types of UCNP-STED probes are very limited and rely greatly on the specific depletion mechanism. Here, by combining the STED and the energy migration upconversion processes, emissions of Tb3+, Eu3+, Dy3+, and Sm3+ distributed in the shell can all be depleted by interrupting the injected energy flux from the Tm3+-doped core nanoparticles. With the merit of the proposed strategy, new types of UCNP-STED probes are demonstrated to perform emission-varying STED imaging with one single, fixed pair of low-power NIR continuous wave lasers.
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3
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Wang W, Chan YH, Kwon S, Tandukar J, Gao R. Nanoscale fluorescence imaging of biological ultrastructure via molecular anchoring and physical expansion. NANO CONVERGENCE 2022; 9:30. [PMID: 35810234 PMCID: PMC9271151 DOI: 10.1186/s40580-022-00318-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 05/26/2022] [Indexed: 05/25/2023]
Abstract
Nanoscale imaging of biological samples can provide rich morphological and mechanistic information about biological functions and dysfunctions at the subcellular and molecular level. Expansion microscopy (ExM) is a recently developed nanoscale fluorescence imaging method that takes advantage of physical enlargement of biological samples. In ExM, preserved cells and tissues are embedded in a swellable hydrogel, to which the molecules and fluorescent tags in the samples are anchored. When the hydrogel swells several-fold, the effective resolution of the sample images can be improved accordingly via physical separation of the retained molecules and fluorescent tags. In this review, we focus on the early conception and development of ExM from a biochemical and materials perspective. We first examine the general workflow as well as the numerous variations of ExM developed to retain and visualize a broad range of biomolecules, such as proteins, nucleic acids, and membranous structures. We then describe a number of inherent challenges facing ExM, including those associated with expansion isotropy and labeling density, as well as the ongoing effort to address these limitations. Finally, we discuss the prospect and possibility of pushing the resolution and accuracy of ExM to the single-molecule scale and beyond.
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Affiliation(s)
- Wei Wang
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, USA
| | - Yat Ho Chan
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, USA
| | - SoYoung Kwon
- Department of Biomedical and Health Information Sciences, College of Applied Health Sciences, University of Illinois Chicago, Chicago, IL, USA
| | - Jamuna Tandukar
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, USA
| | - Ruixuan Gao
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, USA.
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, USA.
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4
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Liu Y, Peng Z, Peng X, Yan W, Yang Z, Qu J. Shedding New Lights Into STED Microscopy: Emerging Nanoprobes for Imaging. Front Chem 2021; 9:641330. [PMID: 33959587 PMCID: PMC8093789 DOI: 10.3389/fchem.2021.641330] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/15/2021] [Indexed: 12/29/2022] Open
Abstract
First reported in 1994, stimulated emission depletion (STED) microscopy has long been regarded as a powerful tool for real-time superresolved bioimaging . However, high STED light power (101∼3 MW/cm2) is often required to achieve significant resolution improvement, which inevitably introduces phototoxicity and severe photobleaching, damaging the imaging quality, especially for long-term cases. Recently, the employment of nanoprobes (quantum dots, upconversion nanoparticles, carbon dots, polymer dots, AIE dots, etc.) in STED imaging has brought opportunities to overcoming such long-existing issues. These nanomaterials designed for STED imaging show not only lower STED power requirements but also more efficient photoluminescence (PL) and enhanced photostability than organic molecular probes. Herein, we review the recent progress in the development of nanoprobes for STED imaging, to highlight their potential in improving the long-term imaging quality of STED microscopy and broadening its application scope. We also discuss the pros and cons for specific classes of nanoprobes for STED bioimaging in detail to provide practical references for biological researchers seeking suitable imaging kits, promoting the development of relative research field.
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Affiliation(s)
| | | | - Xiao Peng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Wei Yan
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen, China
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5
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He Z, Wang P, Ye X. Novel endoscopic optical diagnostic technologies in medical trial research: recent advancements and future prospects. Biomed Eng Online 2021; 20:5. [PMID: 33407477 PMCID: PMC7789310 DOI: 10.1186/s12938-020-00845-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 12/23/2020] [Indexed: 12/20/2022] Open
Abstract
Novel endoscopic biophotonic diagnostic technologies have the potential to non-invasively detect the interior of a hollow organ or cavity of the human body with subcellular resolution or to obtain biochemical information about tissue in real time. With the capability to visualize or analyze the diagnostic target in vivo, these techniques gradually developed as potential candidates to challenge histopathology which remains the gold standard for diagnosis. Consequently, many innovative endoscopic diagnostic techniques have succeeded in detection, characterization, and confirmation: the three critical steps for routine endoscopic diagnosis. In this review, we mainly summarize researches on emerging endoscopic optical diagnostic techniques, with emphasis on recent advances. We also introduce the fundamental principles and the development of those techniques and compare their characteristics. Especially, we shed light on the merit of novel endoscopic imaging technologies in medical research. For example, hyperspectral imaging and Raman spectroscopy provide direct molecular information, while optical coherence tomography and multi-photo endomicroscopy offer a more extensive detection range and excellent spatial-temporal resolution. Furthermore, we summarize the unexplored application fields of these endoscopic optical techniques in major hospital departments for biomedical researchers. Finally, we provide a brief overview of the future perspectives, as well as bottlenecks of those endoscopic optical diagnostic technologies. We believe all these efforts will enrich the diagnostic toolbox for endoscopists, enhance diagnostic efficiency, and reduce the rate of missed diagnosis and misdiagnosis.
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Affiliation(s)
- Zhongyu He
- Biosensor National Special Laboratory, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, People's Republic of China
| | - Peng Wang
- Biosensor National Special Laboratory, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, People's Republic of China
| | - Xuesong Ye
- Biosensor National Special Laboratory, College of Biomedical Engineering and Instrument Science, Zhejiang University, Hangzhou, 310027, People's Republic of China.
- State Key Laboratory of CAD and CG, Zhejiang University, Hangzhou, 310058, People's Republic of China.
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6
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Smitten KL, Fairbanks SD, Robertson CC, Bernardino de la Serna J, Foster SJ, Thomas JA. Ruthenium based antimicrobial theranostics - using nanoscopy to identify therapeutic targets and resistance mechanisms in Staphylococcus aureus. Chem Sci 2020; 11:70-79. [PMID: 32110358 PMCID: PMC7012045 DOI: 10.1039/c9sc04710g] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/28/2019] [Indexed: 12/13/2022] Open
Abstract
In previous studies we reported that specific dinuclear RuII complexes are particularly active against pathogenic Gram-negative bacteria and, unusually for this class of compounds, appeared to display lowered activity against Gram-positive bacteria. With the aim of identifying resistance mechanisms specific to Gram-positive bacteria, the uptake and antimicrobial activity of the lead complex against Staphylococcus aureus SH1000 and other isolates, including MRSA was investigated. This revealed differential, strain specific, sensitivity to the complex. Exploiting the inherent luminescent properties of the RuII complex, super-resolution STED nanoscopy was used to image its initial interaction with S. aureus and confirm its cellular internalization. Membrane damage assays and transmission electron microscopy confirm that the complex disrupts the bacterial membrane structure before internalization, which ultimately results in a small amount of DNA damage. A known resistance mechanism against cationic antimicrobials in Gram-positive bacteria involves increased expression of the mprF gene as this results in an accumulation of positively charged lysyl-phosphatidylglycerol on the outer leaflet of the cytoplasmic membrane that electrostatically repel cationic species. Consistent with this model, it was found that an mprF deficient strain was particularly susceptible to treatment with the lead complex. More detailed co-staining studies also revealed that the complex was more active in S. aureus strains missing, or with altered, wall teichoic acids.
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Affiliation(s)
- Kirsty L Smitten
- Department of Chemistry , University of Sheffield , Sheffield S10 2TN , UK . ;
- The Florey Institute and Department of Molecular Biology and Biotechnology , University of Sheffield , S10 2TN , UK
| | - Simon D Fairbanks
- Department of Chemistry , University of Sheffield , Sheffield S10 2TN , UK . ;
| | - Craig C Robertson
- Department of Chemistry , University of Sheffield , Sheffield S10 2TN , UK . ;
| | - Jorge Bernardino de la Serna
- National Heart and Lung Institute , Faculty of Medicine , Imperial College London , South Kensington Campus , London SW7 2AZ , UK
- Research Complex at Harwell , Rutherford Appleton Laboratory , Central Laser Facility , United Kingdom Research and Innovation , OX11 0FA , UK
| | - Simon J Foster
- The Florey Institute and Department of Molecular Biology and Biotechnology , University of Sheffield , S10 2TN , UK
| | - Jim A Thomas
- Department of Chemistry , University of Sheffield , Sheffield S10 2TN , UK . ;
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7
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Luo H, Wang G, Yuan L. A special three-layer step-index fiber for building compact STED systems. Sci Rep 2019; 9:8455. [PMID: 31186490 PMCID: PMC6560122 DOI: 10.1038/s41598-019-44905-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 05/23/2019] [Indexed: 11/09/2022] Open
Abstract
Up to now, most of stimulated-emission-depletion (STED) systems were lens-based bulky systems. Exchanging some spatial light paths with optical fiber components will make the systems more flexible and will benefit various fields. A big problem to achieve this goal is that the STED beam generated by the traditional method of bulky systems cannot be maintained in an optical fiber due to its birefringence. In this article, we will introduce a type of special optical fiber. With the special fiber, a dark hollow beam with doughnut-shaped focal spot and a concentric beam with Gaussian-shaped focal spot can be generated at the same time. Parameters of a sample and a compact STED system based on it are demonstrated.
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Affiliation(s)
- Hao Luo
- Key Laboratory of In-Fiber Integrated Optics, Ministry of Education, College of Science, Harbin Engineering University, Harbin, 150001, People's Republic of China
| | - Guiren Wang
- Department of Mechanical Engineering and Biomedical Engineering Program, University of South Carolina, Columbia, SC, 29208, USA
| | - Libo Yuan
- Photonics Research Center, Guilin University of Electronics Technology, Guilin, 541004, People's Republic of China.
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8
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Sepúlveda-Ramírez SP, Toledo-Jacobo L, Garno C, Pal D, Ross C, Ellis A, Shuster CB. Live-cell fluorescence imaging of echinoderm embryos. Methods Cell Biol 2019; 151:379-397. [PMID: 30948020 DOI: 10.1016/bs.mcb.2018.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The rapid development, simplicity and optical clarity of the sea urchin embryo make it an excellent model system for studying the dynamic events of early development. An ever-growing palette of fluorescent proteins and biosensors can now be applied to studying sea urchin development, and there are now a wide variety of imaging modes that can be employed to image sea urchin embryogenesis. However, when performing live-cell imaging, one must take into consideration the sensitivity of embryos (and fluorescent probes) to the intense light associated with confocal microscopes. Here, we discuss general considerations for keeping embryos viable on the microscope stage, as well as probes for imaging cellular membranes and the cytoskeleton. We compare the relative merits of different confocal microscopes for live imaging of embryos and describe the potential for live-cell super-resolution microscopy.
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Affiliation(s)
| | - Leslie Toledo-Jacobo
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Chelsea Garno
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Debadrita Pal
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Clara Ross
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Andrea Ellis
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Charles B Shuster
- Department of Biology, New Mexico State University, Las Cruces, NM, United States.
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9
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Tropomodulin Isoform-Specific Regulation of Dendrite Development and Synapse Formation. J Neurosci 2018; 38:10271-10285. [PMID: 30301754 DOI: 10.1523/jneurosci.3325-17.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 09/25/2018] [Accepted: 10/02/2018] [Indexed: 11/21/2022] Open
Abstract
Neurons of the CNS elaborate highly branched dendritic arbors that host numerous dendritic spines, which serve as the postsynaptic platform for most excitatory synapses. The actin cytoskeleton plays an important role in dendrite development and spine formation, but the underlying mechanisms remain incompletely understood. Tropomodulins (Tmods) are a family of actin-binding proteins that cap the slow-growing (pointed) end of actin filaments, thereby regulating the stability, length, and architecture of complex actin networks in diverse cell types. Three members of the Tmod family, Tmod1, Tmod2, and Tmod3 are expressed in the vertebrate CNS, but their function in neuronal development is largely unknown. In this study, we present evidence that Tmod1 and Tmod2 exhibit distinct roles in regulating spine development and dendritic arborization, respectively. Using rat hippocampal tissues from both sexes, we find that Tmod1 and Tmod2 are expressed with distinct developmental profiles: Tmod2 is expressed early during hippocampal development, whereas Tmod1 expression coincides with synaptogenesis. We then show that knockdown of Tmod2, but not Tmod1, severely impairs dendritic branching. Both Tmod1 and Tmod2 are localized to a distinct subspine region where they regulate local F-actin stability. However, the knockdown of Tmod1, but not Tmod2, disrupts spine morphogenesis and impairs synapse formation. Collectively, these findings demonstrate that regulation of the actin cytoskeleton by different members of the Tmod family plays an important role in distinct aspects of dendrite and spine development.SIGNIFICANCE STATEMENT The Tropomodulin family of molecules is best known for controlling the length and stability of actin myofilaments in skeletal muscles. While several Tropomodulin members are expressed in the brain, fundamental knowledge about their role in neuronal function is limited. In this study, we show the unique expression profile and subcellular distribution of Tmod1 and Tmod2 in hippocampal neurons. While both Tmod1 and Tmod2 regulate F-actin stability, we find that they exhibit isoform-specific roles in dendrite development and synapse formation: Tmod2 regulates dendritic arborization, whereas Tmod1 is required for spine development and synapse formation. These findings provide novel insight into the actin regulatory mechanisms underlying neuronal development, thereby shedding light on potential pathways disrupted in a number of neurological disorders.
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10
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Barentine AE, Schroeder LK, Graff M, Baddeley D, Bewersdorf J. Simultaneously Measuring Image Features and Resolution in Live-Cell STED Images. Biophys J 2018; 115:951-956. [PMID: 30139523 PMCID: PMC6139878 DOI: 10.1016/j.bpj.2018.07.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 06/27/2018] [Accepted: 07/24/2018] [Indexed: 11/26/2022] Open
Abstract
Reliable interpretation and quantification of cellular features in fluorescence microscopy requires an accurate estimate of microscope resolution. This is typically obtained by measuring the image of a nonbiological proxy for a point-like object, such as a fluorescent bead. Although appropriate for confocal microscopy, bead-based measurements are problematic for stimulated emission depletion microscopy and similar techniques where the resolution depends critically on the choice of fluorophore and acquisition parameters. In this article, we demonstrate that for a known geometry (e.g., tubules), the resolution can be measured in situ by fitting a model that accounts for both the point spread function (PSF) and the fluorophore distribution. To address the problem of coupling between tubule diameter and PSF width, we developed a technique called nested-loop ensemble PSF fitting. This approach enables extraction of the size of cellular features and the PSF width in fixed-cell and live-cell images without relying on beads or precalibration. Nested-loop ensemble PSF fitting accurately recapitulates microtubule diameter from stimulated emission depletion images and can measure the diameter of endoplasmic reticulum tubules in live COS-7 cells. Our algorithm has been implemented as a plugin for the PYthon Microscopy Environment, a freely available and open-source software.
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Affiliation(s)
- Andrew E.S. Barentine
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut,Department of Biomedical Engineering, Yale University, New Haven, Connecticut
| | - Lena K. Schroeder
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
| | - Michael Graff
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut
| | - David Baddeley
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut; Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand.
| | - Joerg Bewersdorf
- Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut; Department of Biomedical Engineering, Yale University, New Haven, Connecticut.
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11
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Applications of STED fluorescence nanoscopy in unravelling nanoscale structure and dynamics of biological systems. J Biosci 2018. [DOI: 10.1007/s12038-018-9764-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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12
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Vangindertael J, Camacho R, Sempels W, Mizuno H, Dedecker P, Janssen KPF. An introduction to optical super-resolution microscopy for the adventurous biologist. Methods Appl Fluoresc 2018; 6:022003. [DOI: 10.1088/2050-6120/aaae0c] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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13
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Vicidomini G, Bianchini P, Diaspro A. STED super-resolved microscopy. Nat Methods 2018; 15:173-182. [DOI: 10.1038/nmeth.4593] [Citation(s) in RCA: 295] [Impact Index Per Article: 49.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 08/23/2017] [Indexed: 12/18/2022]
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14
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Wang Y, Bai Z, Wang Q, Wang G. Experimental Investigations on Fluorescence Excitation and Depletion of Carbon Dots. J Fluoresc 2017; 27:1435-1441. [PMID: 28421321 DOI: 10.1007/s10895-017-2082-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 04/04/2017] [Indexed: 01/15/2023]
Abstract
Carbon dots (CDs) can be readily synthesized and utilized as attractive fluorescent probes for a variety of applications. In this study, we have synthesized CDs using a previously published method and characterized their photo-physical properties. The resultant CDs possess prominent photo-stability and short emission wavelength in the violet region. Our study reveals that CDs, with weak photo-bleaching, enable them to be employed to achieve high spatial resolution in stimulated emission depletion (STED) microscopy. The depletion efficiency can reach 60%. More importantly, the shorter excitation wavelength of CDs contributes to further improvement of resolution for STED microscopy. An excellent candidate for fluorophores, these CDs have potential to be used in super-resolution imaging for STED microscopy.
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Affiliation(s)
- Yunxia Wang
- Biomedical Engineering Program & Department of Mechanical Engineering, University of South Carolina, Columbia, SC, 29208, USA
| | - Zhenhua Bai
- Biomedical Engineering Program & Department of Mechanical Engineering, University of South Carolina, Columbia, SC, 29208, USA
| | - Qian Wang
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, 29208, USA.
| | - Guiren Wang
- Biomedical Engineering Program & Department of Mechanical Engineering, University of South Carolina, Columbia, SC, 29208, USA.
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15
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Hebisch E, Wagner E, Westphal V, Sieber JJ, Lehnart SE. A protocol for registration and correction of multicolour STED superresolution images. J Microsc 2017; 267:160-175. [PMID: 28370211 DOI: 10.1111/jmi.12556] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 02/01/2017] [Accepted: 02/21/2017] [Indexed: 11/28/2022]
Abstract
Multicolour fluorescence imaging by STimulated Emission Depletion (STED) superresolution microscopy with doughnut-shaped STED laser beams based on different wavelengths for each colour channel requires precise image registration. This is especially important when STED imaging is used for co-localisation studies of two or more native proteins in biological specimens to analyse nanometric subcellular spatial arrangements. We developed a robust postprocessing image registration protocol, with the aim to verify and ultimately optimise multicolour STED image quality. Importantly, this protocol will support any subsequent quantitative localisation analysis at nanometric scales. Henceforth, using an approach that registers each colour channel present during STED imaging individually, this protocol reliably corrects for optical aberrations and inadvertent sample drift. To achieve the latter goal, the protocol combines the experimental sample information, from corresponding STED and confocal images using the same optical beam path and setup, with that of an independent calibration sample. As a result, image registration is based on a strategy that maximises the cross-correlation between sequentially acquired images of the experimental sample, which are strategically combined by the protocol. We demonstrate the general applicability of the image registration protocol by co-staining of the ryanodine receptor calcium release channel in primary mouse cardiomyocytes. To validate this new approach, we identify user-friendly criteria, which - if fulfilled - support optimal image registration. In summary, we introduce a new method for image registration and rationally based postprocessing steps through a highly standardised protocol for multicolour STED imaging, which directly supports the reproducibility of protein co-localisation analyses. Although the reference protocol is discussed exemplarily for two-colour STED imaging, it can be readily expanded to three or more colours and STED channels.
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Affiliation(s)
- E Hebisch
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - E Wagner
- Heart Research Center Göttingen, Department of Cardiology & Pulmonology, University Medical Center Göttingen, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK) site Göttingen, Göttingen, Germany
| | - V Westphal
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - J J Sieber
- Leica Microsystems CMS GmbH, Mannheim, Germany
| | - S E Lehnart
- Heart Research Center Göttingen, Department of Cardiology & Pulmonology, University Medical Center Göttingen, Göttingen, Germany.,German Center for Cardiovascular Research (DZHK) site Göttingen, Göttingen, Germany
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16
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Affiliation(s)
- Hans Blom
- Royal Institute of Technology (KTH), Dept Applied Physics, SciLifeLab, 17165 Solna, Sweden
| | - Jerker Widengren
- Royal Institute of Technology (KTH), Dept Applied Physics, Albanova Univ Center, 10691 Stockholm, Sweden
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17
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Lambert TJ, Waters JC. Navigating challenges in the application of superresolution microscopy. J Cell Biol 2017; 216:53-63. [PMID: 27920217 PMCID: PMC5223610 DOI: 10.1083/jcb.201610011] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 11/15/2016] [Accepted: 11/18/2016] [Indexed: 11/22/2022] Open
Abstract
In 2014, the Nobel Prize in Chemistry was awarded to three scientists who have made groundbreaking contributions to the field of superresolution (SR) microscopy (SRM). The first commercial SR microscope came to market a decade earlier, and many other commercial options have followed. As commercialization has lowered the barrier to using SRM and the awarding of the Nobel Prize has drawn attention to these methods, biologists have begun adopting SRM to address a wide range of questions in many types of specimens. There is no shortage of reviews on the fundamental principles of SRM and the remarkable achievements made with these methods. We approach SRM from another direction: we focus on the current practical limitations and compromises that must be made when designing an SRM experiment. We provide information and resources to help biologists navigate through common pitfalls in SRM specimen preparation and optimization of image acquisition as well as errors and artifacts that may compromise the reproducibility of SRM data.
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Affiliation(s)
- Talley J Lambert
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
| | - Jennifer C Waters
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115
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18
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Byrne A, Burke CS, Keyes TE. Precision targeted ruthenium(ii) luminophores; highly effective probes for cell imaging by stimulated emission depletion (STED) microscopy. Chem Sci 2016; 7:6551-6562. [PMID: 28042459 PMCID: PMC5131359 DOI: 10.1039/c6sc02588a] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 06/29/2016] [Indexed: 12/18/2022] Open
Abstract
Fluorescence microscopy has undergone a dramatic evolution over the past two decades with development of super-resolution far-field microscopy methods that break the light diffraction limited resolution of conventional microscopy, offering unprecedented opportunity to interrogate cellular processes at the nanoscale. However, these methods make special demands of the luminescent agents used for contrast and development of probes suited to super-resolution fluorescent methods is still relatively in its infancy. In spite of their many photophysical advantages, metal complex luminophores have not yet been considered as probes in this regard, where to date, only organic fluorophores have been applied. Here, we report the first examples of metal complex luminophores applied as probes for use in stimulated emission depletion (STED) microscopy. Exemplified with endoplasmic reticulum and nuclear targeting complexes we demonstrate that luminescent Ru(ii) polypyridyl complexes can, through signal peptide targeting, be precisely and selectively delivered to key cell organelles without the need for membrane permeabilization, to give high quality STED images of these organelles. Detailed features of the tubular ER structure are revealed and in the case of the nuclear targeting probe we exploit the molecular light switch properties of a dipyrido[3,2-a:2',3'-c]phenazine containing complex which emits only on DNA/RNA binding to give outstanding STED contrast and resolution of the chromosomes within the nucleus. Comparing performance with a member of the AlexaFluor family commonly recommended for STED, we find that the performance of the ruthenium complexes is superior across both CW and gated STED microscopy methods in terms of image resolution and photostability. The large Stokes shifts of the Ru probes permit excellent matching of the stimulating depletion laser with their emission whilst avoiding anti-Stokes excitation. Their long lifetimes make them particularly amenable to gated STED, giving a much wider window for gating than traditional probes. Our findings indicate that ruthenium polypyridyl peptide targeted probes are a powerful new partner to STED microscopy, opening up new approaches to probe design for STED microscopy.
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Affiliation(s)
- Aisling Byrne
- School of Chemical Sciences , National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland . ; National Biophotonics and Imaging Platform , DCU , Ireland
| | - Christopher S Burke
- School of Chemical Sciences , National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland . ; National Biophotonics and Imaging Platform , DCU , Ireland
| | - Tia E Keyes
- School of Chemical Sciences , National Centre for Sensor Research , Dublin City University , Dublin 9 , Ireland . ; National Biophotonics and Imaging Platform , DCU , Ireland
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19
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Sergé A. The Molecular Architecture of Cell Adhesion: Dynamic Remodeling Revealed by Videonanoscopy. Front Cell Dev Biol 2016; 4:36. [PMID: 27200348 PMCID: PMC4854873 DOI: 10.3389/fcell.2016.00036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/18/2016] [Indexed: 12/20/2022] Open
Abstract
The plasma membrane delimits the cell, which is the basic unit of living organisms, and is also a privileged site for cell communication with the environment. Cell adhesion can occur through cell-cell and cell-matrix contacts. Adhesion proteins such as integrins and cadherins also constitute receptors for inside-out and outside-in signaling within proteolipidic platforms. Adhesion molecule targeting and stabilization relies on specific features such as preferential segregation by the sub-membrane cytoskeleton meshwork and within membrane proteolipidic microdomains. This review presents an overview of the recent insights brought by the latest developments in microscopy, to unravel the molecular remodeling occurring at cell contacts. The dynamic aspect of cell adhesion was recently highlighted by super-resolution videomicroscopy, also named videonanoscopy. By circumventing the diffraction limit of light, nanoscopy has allowed the monitoring of molecular localization and behavior at the single-molecule level, on fixed and living cells. Accessing molecular-resolution details such as quantitatively monitoring components entering and leaving cell contacts by lateral diffusion and reversible association has revealed an unexpected plasticity. Adhesion structures can be highly specialized, such as focal adhesion in motile cells, as well as immune and neuronal synapses. Spatiotemporal reorganization of adhesion molecules, receptors, and adaptors directly relates to structure/function modulation. Assembly of these supramolecular complexes is continuously balanced by dynamic events, remodeling adhesions on various timescales, notably by molecular conformation switches, lateral diffusion within the membrane and endo/exocytosis. Pathological alterations in cell adhesion are involved in cancer evolution, through cancer stem cell interaction with stromal niches, growth, extravasation, and metastasis.
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Affiliation(s)
- Arnauld Sergé
- Centre de Cancérologie de Marseille, Équipe "Interactions Leuco/Stromales", Institut Paoli-Calmettes, Institut National de la Santé et de la Recherche Médicale U1068, Centre National de la Recherche Scientifique UMR7258, Aix-Marseille Université UM105 Marseille, France
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20
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Abstract
The majority of studies of the living cell rely on capturing images using fluorescence microscopy. Unfortunately, for centuries, diffraction of light was limiting the spatial resolution in the optical microscope: structural and molecular details much finer than about half the wavelength of visible light (~200 nm) could not be visualized, imposing significant limitations on this otherwise so promising method. The surpassing of this resolution limit in far-field microscopy is currently one of the most momentous developments for studying the living cell, as the move from microscopy to super-resolution microscopy or 'nanoscopy' offers opportunities to study problems in biophysical and biomedical research at a new level of detail. This review describes the principles and modalities of present fluorescence nanoscopes, as well as their potential for biophysical and cellular experiments. All the existing nanoscopy variants separate neighboring features by transiently preparing their fluorescent molecules in states of different emission characteristics in order to make the features discernible. Usually these are fluorescent 'on' and 'off' states causing the adjacent molecules to emit sequentially in time. Each of the variants can in principle reach molecular spatial resolution and has its own advantages and disadvantages. Some require specific transitions and states that can be found only in certain fluorophore subfamilies, such as photoswitchable fluorophores, while other variants can be realized with standard fluorescent labels. Similar to conventional far-field microscopy, nanoscopy can be utilized for dynamical, multi-color and three-dimensional imaging of fixed and live cells, tissues or organisms. Lens-based fluorescence nanoscopy is poised for a high impact on future developments in the life sciences, with the potential to help solve long-standing quests in different areas of scientific research.
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21
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Niehörster T, Löschberger A, Gregor I, Krämer B, Rahn HJ, Patting M, Koberling F, Enderlein J, Sauer M. Multi-target spectrally resolved fluorescence lifetime imaging microscopy. Nat Methods 2016; 13:257-62. [PMID: 26808668 DOI: 10.1038/nmeth.3740] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/16/2015] [Indexed: 01/09/2023]
Abstract
We introduce a pattern-matching technique for efficient identification of fluorophore ratios in complex multidimensional fluorescence signals using reference fluorescence decay and spectral signature patterns of individual fluorescent probes. Alternating pulsed laser excitation at three different wavelengths and time-resolved detection on 32 spectrally separated detection channels ensures efficient excitation of fluorophores and a maximum gain of fluorescence information. Using spectrally resolved fluorescence lifetime imaging microscopy (sFLIM), we were able to visualize up to nine different target molecules simultaneously in mouse C2C12 cells. By exploiting the sensitivity of fluorescence emission spectra and the lifetime of organic fluorophores on environmental factors, we carried out fluorescence imaging of three different target molecules in human U2OS cells with the same fluorophore. Our results demonstrate that sFLIM can be used for super-resolution multi-target imaging by stimulated emission depletion (STED).
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Affiliation(s)
- Thomas Niehörster
- Department of Biotechnology &Biophysics, Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Anna Löschberger
- Department of Biotechnology &Biophysics, Julius Maximilian University of Würzburg, Würzburg, Germany
| | - Ingo Gregor
- Drittes Physikalisches Institut, Georg-August-Universität, Göttingen, Germany
| | | | | | | | | | - Jörg Enderlein
- Drittes Physikalisches Institut, Georg-August-Universität, Göttingen, Germany
| | - Markus Sauer
- Department of Biotechnology &Biophysics, Julius Maximilian University of Würzburg, Würzburg, Germany
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22
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Abstract
The characteristic lengths of molecular arrangement in primary cilia are below the diffraction limit of light, challenging structural and functional studies of ciliary proteins. Superresolution microscopy can reach up to a 20 nm resolution, significantly improving the ability to map molecules in primary cilia. Here we describe detailed experimental procedure of STED microscopy imaging and dSTORM imaging, two of the most powerful superresolution imaging techniques. Specifically, we emphasize the use of these two methods on imaging proteins in primary cilia.
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Affiliation(s)
- T Tony Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, No 1, Roosevelt Rd. Sec 4, Taipei, 10617, Taiwan
| | - Weng Man Chong
- Institute of Atomic and Molecular Sciences, Academia Sinica, No 1, Roosevelt Rd. Sec 4, Taipei, 10617, Taiwan
| | - Jung-Chi Liao
- Institute of Atomic and Molecular Sciences, Academia Sinica, No 1, Roosevelt Rd. Sec 4, Taipei, 10617, Taiwan.
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23
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Castro JB, Gould TJ. Neuro at the Nanoscale: Diffraction-Unlimited Imaging with STED Nanoscopy. J Histochem Cytochem 2015; 63:897-907. [PMID: 26392517 DOI: 10.1369/0022155415610169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/20/2015] [Indexed: 01/29/2023] Open
Abstract
Recent breakthroughs in fluorescence microscopy have pushed spatial resolution well beyond the classical limit imposed by diffraction. As a result, the field of nanoscopy has emerged, and diffraction-unlimited resolution is becoming increasingly common in biomedical imaging applications. In this review, we recap the principles behind STED nanoscopy that allow imaging beyond the diffraction limit, and highlight both historical and recent advances made in the field of neuroscience as a result of this technology.
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Affiliation(s)
- Jason B Castro
- Department of Psychology and Program in Neuroscience , Bates College, Lewiston, Maine.(JBC)
| | - Travis J Gould
- Department of Physics & Astronomy, Bates College, Lewiston, Maine. (TJG)
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24
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Abstract
The increasing interest in "seeing" the molecular environment in biological systems has led to the recent quest for breaking the diffraction barrier in far-field fluorescence microscopy. The first nanoscopy method successfully applied to conventional biological probes was stimulated emission depletion microscopy (STED). It is based on a physical principle that instantly delivers diffraction-unlimited images, with no need for further computational processing: the excitation laser beam is overlaid with a doughnut-shaped depleting beam that switches off previously excited fluorophores, thereby resulting in what is effectively a smaller imaging volume. In this chapter we give an overview of several applications of STED microscopy to biological questions. We explain technical aspects of sample preparation and image acquisition that will help in obtaining good diffraction-unlimited pictures. We also present embedding techniques adapted for ultrathin sectioning, which allow optimal 3D resolutions in virtually all biological preparations.
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Affiliation(s)
- Natalia H Revelo
- Department of Neuro- and Sensory Physiology, University Medical Center Göttingen, Humboldtallee 23, Göttingen, Germany,
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25
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Curthoys NM, Parent M, Mlodzianoski M, Nelson AJ, Lilieholm J, Butler MB, Valles M, Hess ST. Dances with Membranes: Breakthroughs from Super-resolution Imaging. CURRENT TOPICS IN MEMBRANES 2015; 75:59-123. [PMID: 26015281 PMCID: PMC5584789 DOI: 10.1016/bs.ctm.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Biological membrane organization mediates numerous cellular functions and has also been connected with an immense number of human diseases. However, until recently, experimental methodologies have been unable to directly visualize the nanoscale details of biological membranes, particularly in intact living cells. Numerous models explaining membrane organization have been proposed, but testing those models has required indirect methods; the desire to directly image proteins and lipids in living cell membranes is a strong motivation for the advancement of technology. The development of super-resolution microscopy has provided powerful tools for quantification of membrane organization at the level of individual proteins and lipids, and many of these tools are compatible with living cells. Previously inaccessible questions are now being addressed, and the field of membrane biology is developing rapidly. This chapter discusses how the development of super-resolution microscopy has led to fundamental advances in the field of biological membrane organization. We summarize the history and some models explaining how proteins are organized in cell membranes, and give an overview of various super-resolution techniques and methods of quantifying super-resolution data. We discuss the application of super-resolution techniques to membrane biology in general, and also with specific reference to the fields of actin and actin-binding proteins, virus infection, mitochondria, immune cell biology, and phosphoinositide signaling. Finally, we present our hopes and expectations for the future of super-resolution microscopy in the field of membrane biology.
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Affiliation(s)
- Nikki M. Curthoys
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Matthew Parent
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | | | - Andrew J. Nelson
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Jennifer Lilieholm
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Michael B. Butler
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Matthew Valles
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Samuel T. Hess
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
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26
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Bianchini P, Peres C, Oneto M, Galiani S, Vicidomini G, Diaspro A. STED nanoscopy: a glimpse into the future. Cell Tissue Res 2015; 360:143-50. [PMID: 25743695 PMCID: PMC4379395 DOI: 10.1007/s00441-015-2146-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 02/02/2015] [Indexed: 11/30/2022]
Abstract
The well-known saying of “Seeing is believing” became even more apt in biology when stimulated emission depletion (STED) nanoscopy was introduced in 1994 by the Nobel laureate S. Hell and coworkers. We presently stand at a juncture. Nanoscopy represented a revolution in fluorescence microscopy but now is a mature technique applied to many branches of biology, physics, chemistry, and materials science. We are currently looking ahead to the next generation of optical nanoscopes, to the new key player that will arise in the forthcoming years. This article gives an overview of the various cutting-edge implementations of STED nanoscopy and tries to shine a light into the future: imaging everything faster with unprecedented sensitivity and label-free.
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Affiliation(s)
- Paolo Bianchini
- Nanoscopy, Nanophysics, Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy,
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27
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Diffraction-unlimited imaging: from pretty pictures to hard numbers. Cell Tissue Res 2015; 360:151-78. [DOI: 10.1007/s00441-014-2109-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 12/22/2014] [Indexed: 10/23/2022]
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28
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Ehmann N, Sauer M, Kittel RJ. Super-resolution microscopy of the synaptic active zone. Front Cell Neurosci 2015; 9:7. [PMID: 25688186 PMCID: PMC4311638 DOI: 10.3389/fncel.2015.00007] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 01/07/2015] [Indexed: 12/31/2022] Open
Abstract
Brain function relies on accurate information transfer at chemical synapses. At the presynaptic active zone (AZ) a variety of specialized proteins are assembled to complex architectures, which set the basis for speed, precision and plasticity of synaptic transmission. Calcium channels are pivotal for the initiation of excitation-secretion coupling and, correspondingly, capture a central position at the AZ. Combining quantitative functional studies with modeling approaches has provided predictions of channel properties, numbers and even positions on the nanometer scale. However, elucidating the nanoscopic organization of the surrounding protein network requires direct ultrastructural access. Without this information, knowledge of molecular synaptic structure-function relationships remains incomplete. Recently, super-resolution microscopy (SRM) techniques have begun to enter the neurosciences. These approaches combine high spatial resolution with the molecular specificity of fluorescence microscopy. Here, we discuss how SRM can be used to obtain information on the organization of AZ proteins.
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Affiliation(s)
- Nadine Ehmann
- Department of Neurophysiology, Institute of Physiology, University of Würzburg Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, University of Würzburg Würzburg, Germany
| | - Robert J Kittel
- Department of Neurophysiology, Institute of Physiology, University of Würzburg Würzburg, Germany
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29
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Bijlard AC, Kaltbeitzel A, Avlasevich Y, Crespy D, Hamm M, Landfester K, Taden A. Dual-compartment nanofibres: separation of two highly reactive components in close vicinity. RSC Adv 2015. [DOI: 10.1039/c5ra17750b] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nanofibers based on polyvinyl alcohol encapsulating epoxy and amine colloids in close vicinity as reactive compartments are investigated. Their crosslinking can be initiated upon thermal or mechanical stimuli and enables self-healing applications.
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Affiliation(s)
- Ann-Christin Bijlard
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
- Henkel AG & Co. KGaA
- 40589 Düsseldorf
| | | | | | - Daniel Crespy
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
| | - Marc Hamm
- Henkel AG & Co. KGaA
- 40589 Düsseldorf
- Germany
| | | | - Andreas Taden
- Max Planck Institute for Polymer Research
- 55128 Mainz
- Germany
- Henkel AG & Co. KGaA
- 40589 Düsseldorf
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30
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Abstract
Optical imaging is crucial for addressing fundamental problems in all areas of life science. With the use of confocal and two-photon fluorescence microscopy, complex dynamic structures and functions in a plethora of tissue and cell types have been visualized. However, the resolution of 'classical' optical imaging methods is poor due to the diffraction limit and does not allow resolution of the cellular microcosmos. On the other hand, the novel stimulated emission depletion (STED) microscopy technique, because of its targeted on/off-switching of fluorescence, is not hampered by a diffraction-limited resolution barrier. STED microscopy can therefore provide much sharper images, permitting nanoscale visualization by sequential imaging of individual-labelled biomolecules, which should allow previous findings to be reinvestigated and provide novel information. The aim of this review is to highlight promising developments in and applications of STED microscopy and their impact on unresolved issues in biomedical science.
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Affiliation(s)
- H Blom
- Science for Life Laboratory, Royal Institute of Technology, Stockholm, Sweden
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31
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Pi J, Jin H, Yang F, Chen ZW, Cai J. In situ single molecule imaging of cell membranes: linking basic nanotechniques to cell biology, immunology and medicine. NANOSCALE 2014; 6:12229-12249. [PMID: 25227707 DOI: 10.1039/c4nr04195j] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The cell membrane, which consists of a viscous phospholipid bilayer, different kinds of proteins and various nano/micrometer-sized domains, plays a very important role in ensuring the stability of the intracellular environment and the order of cellular signal transductions. Exploring the precise cell membrane structure and detailed functions of the biomolecules in a cell membrane would be helpful to understand the underlying mechanisms involved in cell membrane signal transductions, which could further benefit research into cell biology, immunology and medicine. The detection of membrane biomolecules at the single molecule level can provide some subtle information about the molecular structure and the functions of the cell membrane. In particular, information obtained about the molecular mechanisms and other information at the single molecule level are significantly different from that detected from a large amount of biomolecules at the large-scale through traditional techniques, and can thus provide a novel perspective for the study of cell membrane structures and functions. However, the precise investigations of membrane biomolecules prompts researchers to explore cell membranes at the single molecule level by the use of in situ imaging methods, as the exact conformation and functions of biomolecules are highly controlled by the native cellular environment. Recently, the in situ single molecule imaging of cell membranes has attracted increasing attention from cell biologists and immunologists. The size of biomolecules and their clusters on the cell surface are set at the nanoscale, which makes it mandatory to use high- and super-resolution imaging techniques to realize the in situ single molecule imaging of cell membranes. In the past few decades, some amazing imaging techniques and instruments with super resolution have been widely developed for molecule imaging, which can also be further employed for the in situ single molecule imaging of cell membranes. In this review, we attempt to summarize the characteristics of these advanced techniques for use in the in situ single molecule imaging of cell membranes. We believe that this work will help to promote the technological and methodological developments of super-resolution techniques for the single molecule imaging of cell membranes and help researchers better understand which technique is most suitable for their future exploring of membrane biomolecules; ultimately promoting further developments in cell biology, immunology and medicine.
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Affiliation(s)
- Jiang Pi
- State Key Laboratory of Quality Research in Chinese Medicines, Macau University of Science and Technique, Macau, China.
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32
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Wu X, Toro L, Stefani E, Wu Y. Ultrafast photon counting applied to resonant scanning STED microscopy. J Microsc 2014; 257:31-8. [PMID: 25227160 DOI: 10.1111/jmi.12183] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Accepted: 08/20/2014] [Indexed: 11/26/2022]
Abstract
To take full advantage of fast resonant scanning in super-resolution stimulated emission depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multigiga sample per second analogue-to-digital conversion chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (∼50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time-gated continuous wave STED technology to the usage of resonant scanning with hardware-based time-gating. The assembled system provides superb signal-to-noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant-scanning continuous wave STED microscopy with online time-gated detection.
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Affiliation(s)
- Xundong Wu
- Division of Molecular Medicine, Department of Anesthesiology, David Geffen School of Medicine, University of California, Los Angeles, California, U.S.A
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33
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Schreiner AE, Durry S, Aida T, Stock MC, Rüther U, Tanaka K, Rose CR, Kafitz KW. Laminar and subcellular heterogeneity of GLAST and GLT-1 immunoreactivity in the developing postnatal mouse hippocampus. J Comp Neurol 2014; 522:204-24. [PMID: 23939750 DOI: 10.1002/cne.23450] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 05/23/2013] [Accepted: 08/02/2013] [Indexed: 11/06/2022]
Abstract
Astrocytes express two sodium-coupled transporters, glutamate-aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1), which are essential for the maintenance of low extracellular glutamate levels. We performed a comparative analysis of the laminar and subcellular expression profile of GLAST and GLT-1 in the developing postnatal mouse hippocampus by using immunohistochemistry and western blotting and employing high-resolution fluorescence microscopy. Astrocytes were identified by costaining with glial fibrillary acidic protein (GFAP) or S100β. In CA1, the density of GFAP-positive cells and GFAP expression rose during the first 2 weeks after birth, paralleled by a steady increase in GLAST immunoreactivity and protein content. Upregulation of GLT-1 was completed only at postnatal days (P) P20-25 and was thus delayed by about 10 days. GLAST staining was highest along the stratum pyramidale and was especially prominent in astrocytes at P3-5. GLAST immunoreactivity indicated no preferential localization to a specific cellular compartment. GLT-1 exhibited a laminar expression pattern from P10-15 on, with the highest immunoreactivity in the stratum lacunosum-moleculare. At the cellular level, GLT-1 immunoreactivity did not entirely cover astrocyte somata and exhibited clusters at processes. In neonatal and juvenile animals, discrete clusters of GLT-1 were also detected at perivascular endfeet. From these results, we conclude there is a remarkable subcellular heterogeneity of GLAST and GLT-1 expression in the developing hippocampus. The clustering of GLT-1 at astrocyte endfeet indicates that it might serve a specialized functional role at the blood-brain barrier during formation of the hippocampal network.
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Affiliation(s)
- Alexandra E Schreiner
- Institute of Neurobiology, Heinrich Heine University Duesseldorf, 40225, Duesseldorf, Germany
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34
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Chozinski TJ, Gagnon LA, Vaughan JC. Twinkle, twinkle little star: photoswitchable fluorophores for super-resolution imaging. FEBS Lett 2014; 588:3603-12. [PMID: 25010263 DOI: 10.1016/j.febslet.2014.06.043] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 06/14/2014] [Accepted: 06/16/2014] [Indexed: 01/01/2023]
Abstract
Photoswitchable fluorescent probes are key elements of newly developed super-resolution fluorescence microscopy techniques that enable far-field interrogation of biological systems with a resolution of 50 nm or better. In contrast to most conventional fluorescence imaging techniques, the performance achievable by most super-resolution techniques is critically impacted by the photoswitching properties of the fluorophores. Here we review photoswitchable fluorophores for super-resolution imaging with discussion of the fundamental principles involved, a focus on practical implementation with available tools, and an outlook on future directions.
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Affiliation(s)
| | - Lauren A Gagnon
- Department of Chemistry, University of Washington, Seattle, WA, USA
| | - Joshua C Vaughan
- Department of Chemistry, University of Washington, Seattle, WA, USA; Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA.
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35
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Abstract
The isotopic composition of different materials can be imaged by secondary ion mass spectrometry. In biology, this method is mainly used to study cellular metabolism and turnover, by pulsing the cells with marker molecules such as amino acids labelled with stable isotopes (15N, 13C). The incorporation of the markers is then imaged with a lateral resolution that can surpass 100 nm. However, secondary ion mass spectrometry cannot identify specific subcellular structures like organelles, and needs to be correlated with a second technique, such as fluorescence imaging. Here, we present a method based on stimulated emission depletion microscopy that provides correlated optical and isotopic nanoscopy (COIN) images. We use this approach to study the protein turnover in different organelles from cultured hippocampal neurons. Correlated optical and isotopic nanoscopy can be applied to a variety of biological samples, and should therefore enable the investigation of the isotopic composition of many organelles and subcellular structures. Secondary ion mass spectrometry is effective for imaging cellular turnover, but it cannot identify subcellular structures such as organelles. Here the authors show a method for correlating this technique with high-resolution fluorescence microscopy, enabling the measurement of turnover in cellular compartments.
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36
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Osseforth C, Moffitt JR, Schermelleh L, Michaelis J. Simultaneous dual-color 3D STED microscopy. OPTICS EXPRESS 2014; 22:7028-39. [PMID: 24664051 DOI: 10.1364/oe.22.007028] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We describe the design and implementation of a stimulated emission depletion (STED) microscope which allows simultaneous three-dimensional super-resolution imaging in two colors. A super-continuum laser source is used to provide all spectral bands necessary for excitation and efficient depletion to achieve a lateral and axial resolution of ~35 nm and ~90 nm respectively. We characterize the systems' performance by imaging colloidal particles and single fluorescent molecules. Its biological applicability is demonstrated by dual-color imaging of nuclear pore complexes and of DNA replication sites in mammalian cells.
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37
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Huang LL, Xie HY. Progress on the labeling and single-particle tracking technologies of viruses. Analyst 2014; 139:3336-46. [DOI: 10.1039/c4an00038b] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We review recent advances in virus labeling and the emerging fluorescence imaging technologies used in the imaging and tracking of viruses.
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Affiliation(s)
- Li-Li Huang
- School of Life Science
- Beijing Institute of Technology
- Beijing 100081, China
| | - Hai-Yan Xie
- School of Life Science
- Beijing Institute of Technology
- Beijing 100081, China
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38
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39
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Beater S, Raab M, Tinnefeld P. Toward quantitative fluorescence microscopy with DNA origami nanorulers. Methods Cell Biol 2014; 123:449-66. [DOI: 10.1016/b978-0-12-420138-5.00024-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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40
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Han R, Li Z, Fan Y, Jiang Y. Recent Advances in Super-Resolution Fluorescence Imaging and Its Applications in Biology. J Genet Genomics 2013; 40:583-95. [DOI: 10.1016/j.jgg.2013.11.003] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 11/11/2013] [Accepted: 11/11/2013] [Indexed: 11/16/2022]
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41
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Hou S, Liang L, Deng S, Chen J, Huang Q, Cheng Y, Fan C. Nanoprobes for super-resolution fluorescence imaging at the nanoscale. Sci China Chem 2013. [DOI: 10.1007/s11426-013-5014-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Seeing the forest tree by tree: super-resolution light microscopy meets the neurosciences. Nat Neurosci 2013; 16:790-7. [PMID: 23799471 DOI: 10.1038/nn.3403] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Accepted: 04/16/2013] [Indexed: 02/07/2023]
Abstract
Light microscopy can be applied in vivo and can sample large tissue volumes, features crucial for the study of single neurons and neural circuits. However, light microscopy per se is diffraction-limited in resolution, and the substructure of core signaling compartments of neuronal circuits--axons, presynaptic active zones, postsynaptic densities and dendritic spines-can be only insufficiently characterized by standard light microscopy. Recently, several forms of super-resolution light microscopy breaking the diffraction-imposed resolution limit have started to allow highly resolved, dynamic imaging in the cell-biologically highly relevant 10-100 nanometer range ('mesoscale'). New, sometimes surprising answers concerning how protein mobility and protein architectures shape neuronal communication have already emerged. Here we start by briefly introducing super-resolution microscopy techniques, before we describe their use in the analysis of neuronal compartments. We conclude with long-term prospects for super-resolution light microscopy in the molecular and cellular neurosciences.
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43
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Cox S, Jones GE. Imaging cells at the nanoscale. Int J Biochem Cell Biol 2013; 45:1669-78. [PMID: 23688552 DOI: 10.1016/j.biocel.2013.05.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 05/09/2013] [Accepted: 05/10/2013] [Indexed: 01/15/2023]
Abstract
Recently developed super-resolution techniques in optical microscopy have pushed the length scale at which cellular structure can be observed down to tens of nanometres. A wide array of methods have been described that fall under the umbrella term of super-resolution microscopy and each of these methods has different requirements for acquisition speed, experimental complexity, fluorophore requirements and post-processing of data. For example, experimental complexity can be decreased by using a standard widefield microscope for acquisition, but this requires substantial processing of the data to extract the super-resolution information. These powerful techniques are bringing new insights into the nanoscale structure of sub-cellular assemblies such as podosomes, which are an ideal system to observe with super-resolution microscopy as the structures are relatively thin and they form and dissociate over a period of several minutes. Here we discuss the major classes of super-resolution microscopy techniques, and demonstrate their relative performance by imaging podosomes.
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Affiliation(s)
- Susan Cox
- Randall Division of Cell & Molecular Biophysics, King's College London, London, UK.
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44
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Nanostructured surfaces and detection instrumentation for photonic crystal enhanced fluorescence. SENSORS 2013; 13:5561-84. [PMID: 23624689 PMCID: PMC3690015 DOI: 10.3390/s130505561] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 03/26/2013] [Accepted: 03/27/2013] [Indexed: 01/15/2023]
Abstract
Photonic crystal (PC) surfaces have been demonstrated as a compelling platform for improving the sensitivity of surface-based fluorescent assays used in disease diagnostics and life science research. PCs can be engineered to support optical resonances at specific wavelengths at which strong electromagnetic fields are utilized to enhance the intensity of surface-bound fluorophore excitation. Meanwhile, the leaky resonant modes of PCs can be used to direct emitted photons within a narrow range of angles for more efficient collection by a fluorescence detection system. The multiplicative effects of enhanced excitation combined with enhanced photon extraction combine to provide improved signal-to-noise ratios for detection of fluorescent emitters, which in turn can be used to reduce the limits of detection of low concentration analytes, such as disease biomarker proteins. Fabrication of PCs using inexpensive manufacturing methods and materials that include replica molding on plastic, nano-imprint lithography on quartz substrates result in devices that are practical for single-use disposable applications. In this review, we will describe the motivation for implementing high-sensitivity fluorescence detection in the context of molecular diagnosis and gene expression analysis though the use of PC surfaces. Recent efforts to improve the design and fabrication of PCs and their associated detection instrumentation are summarized, including the use of PCs coupled with Fabry-Perot cavities and external cavity lasers.
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45
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Chia PZC, Gleeson PA. Imaging and Quantitation Techniques for Tracking Cargo along Endosome-to-Golgi Transport Pathways. Cells 2013; 2:105-23. [PMID: 24709647 PMCID: PMC3972656 DOI: 10.3390/cells2010105] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 02/05/2013] [Accepted: 02/07/2013] [Indexed: 11/20/2022] Open
Abstract
Recent improvements in the resolution of light microscopy, coupled with the development of a range of fluorescent-based probes, have provided new approaches to dissecting membrane domains and the regulation of membrane trafficking. Here, we review these advances, as well as highlight developments in quantitative image analysis and novel unbiased analytical approaches to quantitate protein localization. The application of these approaches to endosomal sorting and endosome-to-Golgi transport is discussed.
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Affiliation(s)
- Pei Zhi Cheryl Chia
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
| | - Paul A Gleeson
- The Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia.
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46
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Mace EM, Orange JS. New views of the human NK cell immunological synapse: recent advances enabled by super- and high-resolution imaging techniques. Front Immunol 2013; 3:421. [PMID: 23316204 PMCID: PMC3540402 DOI: 10.3389/fimmu.2012.00421] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Accepted: 12/20/2012] [Indexed: 12/31/2022] Open
Abstract
Imaging technology has undergone rapid growth with the development of super resolution microscopy, which enables resolution below the diffraction barrier of light (~200 nm). In addition, new techniques for single molecule imaging are being added to the cell biologist's arsenal. Immunologists have exploited these techniques to advance understanding of NK biology, particularly that of the immune synapse. The immune synapse's relatively small size and complex architecture combined with its exquisitely controlled signaling milieu have made it a challenge to visualize. In this review we highlight and discuss new insights into NK cell immune synapse formation and regulation revealed by cutting edge imaging techniques, including super-resolution microscopy, high-resolution total internal reflection microscopy, and Förster resonance energy transfer.
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Affiliation(s)
- Emily M. Mace
- Baylor College of MedicineHouston, TX, USA
- Texas Children’s Hospital Center for Human ImmunobiologyHouston, TX, USA
| | - Jordan S. Orange
- Baylor College of MedicineHouston, TX, USA
- Texas Children’s Hospital Center for Human ImmunobiologyHouston, TX, USA
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Kohl T, Westphal V, Hell SW, Lehnart SE. Superresolution microscopy in heart - cardiac nanoscopy. J Mol Cell Cardiol 2012; 58:13-21. [PMID: 23219451 DOI: 10.1016/j.yjmcc.2012.11.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 11/03/2012] [Accepted: 11/24/2012] [Indexed: 12/23/2022]
Abstract
Detailed understanding of the adaptive nature of cardiac cells in health and disease requires investigation of proteins and membranes in their native physiological environment, ideally by noninvasive optical methods. However, conventional light microscopy does not resolve the spatial characteristics of small fluorescently labeled protein or membrane structures in cells. Due to diffraction limiting resolution to half the wavelength of light, adjacent fluorescent molecules spaced at less than ~250 nm are not separately visualized. This fundamental problem has lead to a rapidly growing area of research, superresolution fluorescence microscopy, also called nanoscopy. We discuss pioneering applications of superresolution microscopy relevant to the heart, emphasizing different nanoscopy strategies toward new insight in cardiac cell biology. Here, we focus on molecular and structural readouts from subcellular nanodomains and organelles related to Ca(2+) signaling during excitation-contraction (EC) coupling, including live cell imaging strategies. Based on existing data and superresolution techniques, we suggest that an important future aim will be subcellular in situ structure-function analysis with nanometric resolving power in organotypic cells.
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Affiliation(s)
- Tobias Kohl
- Heart Research Center Goettingen, University Medicine Goettingen, Germany
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48
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Rönnlund D, Yang Y, Blom H, Auer G, Widengren J. Fluorescence nanoscopy of platelets resolves platelet-state specific storage, release and uptake of proteins, opening up future diagnostic applications. Adv Healthc Mater 2012. [PMID: 23184821 DOI: 10.1002/adhm.201200172] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Dysregulation of how platelets store, sequester and release specific proteins seems to be implicated in many disease states, including cancer. Dual-color immunofluorescence stimulated emission depletion (STED) microscopy with 40 nm resolution is used to map pro-angiogenic VEGF, anti-angiogenic PF-4 and fibrinogen in >300 individual platelets. This reveals that these proteins are stored in a segmented, zonal manner within regional clusters, significantly smaller than the size of an α-granule. No colocalization between the different proteins is observed. Upon platelet activation by thrombin or ADP, the proteins undergo significant spatial rearrangements, including alterations in the size and number of the protein clusters, and specific for a certain protein and the type of activation induced. Following these observations, a simple assignment procedure is used to show that the three distinct states of platelets (non-, ADP- and thrombin-activated) can be identified based on the average size, number and peripheral localization profiles of the regional protein clusters within the platelets. Thus, high-resolution spatial mapping of specific proteins is a useful procedure to detect and characterize deviations in the selective storage, release and uptake of these proteins in the platelets. Since these deviations seem to be specific for, and may even underlie, certain patophysiological states, these findings may have interesting diagnostic and therapeutic implications.
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Affiliation(s)
- Daniel Rönnlund
- Department of Applied Physics/Experimental Biomolecular Physics, Albanova University Center, Stockholm, Sweden
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Tønnesen J, Nägerl UV. Superresolution imaging for neuroscience. Exp Neurol 2012; 242:33-40. [PMID: 23063602 DOI: 10.1016/j.expneurol.2012.10.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 09/04/2012] [Accepted: 10/04/2012] [Indexed: 10/27/2022]
Abstract
The advent of superresolution fluorescence microscopy beyond the classic diffraction barrier of optical microscopy is poised to transform cell-biological research. A series of proof-of-principle studies have demonstrated its vast potential for a wide range of applications in neuroscience, including nanoscale imaging of neuronal morphology, cellular organelles, protein distributions and protein trafficking. This review introduces the main incarnations of these new methodologies, including STED, PALM/STORM and SIM, covering basic theoretical and practical aspects concerning their optical principles, technical implementation, scope and limitations. In addition, it highlights several discoveries relating to synapse biology that have been made using these novel approaches to illustrate their appeal for neuroscience research.
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Affiliation(s)
- Jan Tønnesen
- Université Bordeaux Segalen, Interdisciplinary Institute for Neuroscience, UMR 5297, 146 rue Léo Saignat, 33077 Bordeaux, France
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50
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Aaron JS, Carson BD, Timlin JA. Characterization of differential Toll-like receptor responses below the optical diffraction limit. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3041-9. [PMID: 22807232 PMCID: PMC3613986 DOI: 10.1002/smll.201200106] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Revised: 04/25/2012] [Indexed: 05/18/2023]
Abstract
Many membrane receptors are recruited to specific cell surface domains to form nanoscale clusters upon ligand activation. This step appears to be necessary to initiate cell signaling, including pathways in innate immune system activation. However, virulent pathogens such as Yersinia pestis (the causative agent of plague) are known to evade innate immune detection, in contrast to similar microbes (such as Escherichia coli) that elicit a robust response. This disparity has been partly attributed to the structure of lipopolysaccharides (LPS) on the bacterial cell wall, which are recognized by the innate immune receptor TLR4. It is hypothesized that nanoscale differences exist between the spatial clustering of TLR4 upon binding of LPS derived from Y. pestis and E. coli. Although optical imaging can provide exquisite details of the spatial organization of biomolecules, there is a mismatch between the scale at which receptor clustering occurs (<300 nm) and the optical diffraction limit (>400 nm). The last decade has seen the emergence of super-resolution imaging methods that effectively break the optical diffraction barrier to yield truly nanoscale information in intact biological samples. This study reports the first visualizations of TLR4 distributions on intact cells at image resolutions of <30 nm using a novel, dual-color stochastic optical reconstruction microscopy (STORM) technique. This methodology permits distinction between receptors containing bound LPS from those without at the nanoscale. Importantly, it is also shown that LPS derived from immunostimulatory bacteria result in significantly higher LPS-TLR4 cluster sizes and a nearly twofold greater ligand/receptor colocalization as compared to immunoevading LPS.
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Affiliation(s)
- Jesse S. Aaron
- Sandia National Laboratories PO Box 5800, MS-0895 Albuquerque, NM 87185
| | - Bryan D. Carson
- Sandia National Laboratories PO Box 5800, MS-0895 Albuquerque, NM 87185
| | - Jerilyn A. Timlin
- Sandia National Laboratories PO Box 5800, MS-0895 Albuquerque, NM 87185
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