1
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Galli R, Uckermann O. Vibrational spectroscopy and multiphoton microscopy for label-free visualization of nervous system degeneration and regeneration. Biophys Rev 2024; 16:219-235. [PMID: 38737209 PMCID: PMC11078905 DOI: 10.1007/s12551-023-01158-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 09/22/2023] [Indexed: 05/14/2024] Open
Abstract
Neurological disorders, including spinal cord injury, peripheral nerve injury, traumatic brain injury, and neurodegenerative diseases, pose significant challenges in terms of diagnosis, treatment, and understanding the underlying pathophysiological processes. Label-free multiphoton microscopy techniques, such as coherent Raman scattering, two-photon excited autofluorescence, and second and third harmonic generation microscopy, have emerged as powerful tools for visualizing nervous tissue with high resolution and without the need for exogenous labels. Coherent Raman scattering processes as well as third harmonic generation enable label-free visualization of myelin sheaths, while their combination with two-photon excited autofluorescence and second harmonic generation allows for a more comprehensive tissue visualization. They have shown promise in assessing the efficacy of therapeutic interventions and may have future applications in clinical diagnostics. In addition to multiphoton microscopy, vibrational spectroscopy methods such as infrared and Raman spectroscopy offer insights into the molecular signatures of injured nervous tissues and hold potential as diagnostic markers. This review summarizes the application of these label-free optical techniques in preclinical models and illustrates their potential in the diagnosis and treatment of neurological disorders with a special focus on injury, degeneration, and regeneration. Furthermore, it addresses current advancements and challenges for bridging the gap between research findings and their practical applications in a clinical setting.
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Affiliation(s)
- Roberta Galli
- Medical Physics and Biomedical Engineering, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
| | - Ortrud Uckermann
- Department of Neurosurgery, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Division of Medical Biology, Department of Psychiatry and Psychotherapy, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
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2
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Shen YJ, Liao EY, Tai TM, Liao YH, Sun CK, Lee CK, See S, Chen HW. Deep learning-based photodamage reduction on harmonic generation microscope at low-level optical power. J Biophotonics 2024; 17:e202300285. [PMID: 37738103 DOI: 10.1002/jbio.202300285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 09/10/2023] [Accepted: 09/19/2023] [Indexed: 09/24/2023]
Abstract
The trade-off between high-quality images and cellular health in optical bioimaging is a crucial problem. We demonstrated a deep-learning-based power-enhancement (PE) model in a harmonic generation microscope (HGM), including second harmonic generation (SHG) and third harmonic generation (THG). Our model can predict high-power HGM images from low-power images, greatly reducing the risk of phototoxicity and photodamage. Furthermore, the PE model trained only on normal skin data can also be used to predict abnormal skin data, enabling the dermatopathologist to successfully identify and label cancer cells. The PE model shows potential for in-vivo and ex-vivo HGM imaging.
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Affiliation(s)
- Yi-Jiun Shen
- International Intercollegiate Ph.D. Program, National Tsing Hua University, Hsinchu, Taiwan
| | - En-Yu Liao
- Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan
| | | | - Yi-Hua Liao
- Department of Dermatology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Chi-Kuang Sun
- Department of Electrical Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei, Taiwan
| | | | - Simon See
- NVIDIA AI Technology Center, NVIDIA, Taipei, Taiwan
| | - Hung-Wen Chen
- International Intercollegiate Ph.D. Program, National Tsing Hua University, Hsinchu, Taiwan
- Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan
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3
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Soha SA, Santhireswaran A, Huq S, Casimir-Powell J, Jenkins N, Hodgson GK, Sugiyama M, Antonescu CN, Impellizzeri S, Botelho RJ. Improved imaging and preservation of lysosome dynamics using silver nanoparticle-enhanced fluorescence. Mol Biol Cell 2023; 34:ar96. [PMID: 37405751 PMCID: PMC10551705 DOI: 10.1091/mbc.e22-06-0200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/06/2023] Open
Abstract
The dynamics of living cells can be studied by live-cell fluorescence microscopy. However, this requires the use of excessive light energy to obtain good signal-to-noise ratio, which can then photobleach fluorochromes, and more worrisomely, lead to phototoxicity. Upon light excitation, noble metal nanoparticles such as silver nanoparticles (AgNPs) generate plasmons, which can then amplify excitation in direct proximity of the nanoparticle's surface and couple to the oscillating dipole of nearby radiating fluorophores, modifying their rate of emission and thus, enhancing their fluorescence. Here, we show that AgNPs fed to cells to accumulate within lysosomes enhanced the fluorescence of lysosome-targeted Alexa488-conjugated dextran, BODIPY-cholesterol, and DQ-BSA. Moreover, AgNP increased the fluorescence of GFP fused to the cytosolic tail of LAMP1, showing that metal enhanced fluorescence can occur across the lysosomal membrane. The inclusion of AgNPs in lysosomes did not disturb lysosomal properties such as lysosomal pH, degradative capacity, autophagy and autophagic flux, and membrane integrity, though AgNP seemed to increase basal lysosome tubulation. Importantly, by using AgNP, we could track lysosome motility with reduced laser power without damaging and altering lysosome dynamics. Overall, AgNP-enhanced fluorescence may be a useful tool to study the dynamics of the endo-lysosomal pathway while minimizing phototoxicity.
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Affiliation(s)
- Sumaiya A. Soha
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Araniy Santhireswaran
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Saaimatul Huq
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Jayde Casimir-Powell
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Nicala Jenkins
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Gregory K. Hodgson
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Michael Sugiyama
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Costin N. Antonescu
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Stefania Impellizzeri
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
| | - Roberto J. Botelho
- Molecular Science Graduate Program, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, Ontario, Canada, M5B 2K3
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Hirotsu A, Kikuchi H, Yamada H, Ozaki Y, Haneda R, Kawata S, Murakami T, Matsumoto T, Hiramatsu Y, Kamiya K, Yamashita D, Fujimori Y, Ueda Y, Okazaki S, Kitagawa M, Konno H, Takeuchi H. Artificial intelligence-based classification of peripheral blood nucleated cells using label-free imaging flow cytometry. Lab Chip 2022; 22:3464-3474. [PMID: 35942978 DOI: 10.1039/d2lc00166g] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Label-free image identification of circulating rare cells, such as circulating tumor cells within peripheral blood nucleated cells (PBNCs), the vast majority of which are white blood cells (WBCs), remains challenging. We previously described developing label-free image cytometry for classifying live cells using computer vision technology for pattern recognition, based on the subcellular structure of the quantitative phase microscopy images. We applied our image recognition methods to cells flowing in a flow cytometer microfluidic channel, and differentiated WBCs from cancer cell lines (area under receiver operating characteristic curve = 0.957). We then applied this method to healthy volunteers' and advanced cancer patients' blood samples and found that the non-WBC fraction rates (NWBC-FRs), defined as the percentage of cells classified as non-WBCs of the total PBNCs, were significantly higher in cancer patients than in healthy volunteers. Furthermore, we monitored NWBC-FRs over the therapeutic courses in cancer patients, which revealed the potential ability in monitoring the clinical status during therapy. Our image recognition system has the potential to provide a morphological diagnostic tool for circulating rare cells as non-WBC fractions.
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Affiliation(s)
- Amane Hirotsu
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Hirotoshi Kikuchi
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Hidenao Yamada
- Central Research Laboratory, Hamamatsu Photonics K.K, Hamamatsu, Shizuoka, Japan
| | - Yusuke Ozaki
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Ryoma Haneda
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Sanshiro Kawata
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Tomohiro Murakami
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Tomohiro Matsumoto
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Yoshihiro Hiramatsu
- Department Perioperative Functioning Care and Support, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Kinji Kamiya
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
| | - Daisuke Yamashita
- Central Research Laboratory, Hamamatsu Photonics K.K, Hamamatsu, Shizuoka, Japan
| | - Yuki Fujimori
- Central Research Laboratory, Hamamatsu Photonics K.K, Hamamatsu, Shizuoka, Japan
| | - Yukio Ueda
- Central Research Laboratory, Hamamatsu Photonics K.K, Hamamatsu, Shizuoka, Japan
| | - Shigetoshi Okazaki
- HAMAMATSU BioPhotonics Innovation Chair, Institute for Medical Photonics Research, Preeminent Medical Photonics Education and Research Centre, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Masatoshi Kitagawa
- Department of Molecular Biology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
- Laboratory Animal Facilities and Services, Preeminent Medical Photonics Education and Research Centre, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Hiroyuki Konno
- Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan
| | - Hiroya Takeuchi
- Department of Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu 431-3192, Japan.
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5
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Robitaille MC, Byers JM, Christodoulides JA, Raphael MP. Robust optical flow algorithm for general single cell segmentation. PLoS One 2022; 17:e0261763. [PMID: 35030184 PMCID: PMC8759635 DOI: 10.1371/journal.pone.0261763] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 12/09/2021] [Indexed: 11/19/2022] Open
Abstract
Cell segmentation is crucial to the field of cell biology, as the accurate extraction of single-cell morphology, migration, and ultimately behavior from time-lapse live cell imagery are of paramount importance to elucidate and understand basic cellular processes. In an effort to increase available segmentation tools that can perform across research groups and platforms, we introduce a novel segmentation approach centered around optical flow and show that it achieves robust segmentation of single cells by validating it on multiple cell types, phenotypes, optical modalities, and in-vitro environments with or without labels. By leveraging cell movement in time-lapse imagery as a means to distinguish cells from their background and augmenting the output with machine vision operations, our algorithm reduces the number of adjustable parameters needed for manual optimization to two. We show that this approach offers the advantage of quicker processing times compared to contemporary machine learning based methods that require manual labeling for training, and in most cases achieves higher quality segmentation as well. This algorithm is packaged within MATLAB, offering an accessible means for general cell segmentation in a time-efficient manner.
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Alghamdi RA, Exposito-Rodriguez M, Mullineaux PM, Brooke GN, Laissue PP. Assessing Phototoxicity in a Mammalian Cell Line: How Low Levels of Blue Light Affect Motility in PC3 Cells. Front Cell Dev Biol 2021; 9:738786. [PMID: 34977004 PMCID: PMC8718804 DOI: 10.3389/fcell.2021.738786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 11/16/2021] [Indexed: 11/24/2022] Open
Abstract
Phototoxicity is a significant constraint for live cell fluorescence microscopy. Excessive excitation light intensities change the homeostasis of the observed cells. Erroneous and misleading conclusions may be the problematic consequence of observing such light-induced pathophysiology. In this study, we assess the effect of blue light, as commonly used for GFP and YFP excitation, on a motile mammalian cell line. Tracking PC3 cells at different light doses and intensities, we show how motility can be used to reliably assess subtle positive and negative effects of illumination. We further show that the effects are a factor of intensity rather than light dose. Mitotic delay was not a sensitive indicator of phototoxicity. For early detection of the effect of blue light, we analysed the expression of genes involved in oxidative stress. This study addresses the need for relatively simple and sensitive methods to establish a dose-response curve for phototoxicity in mammalian cell line models. We conclude with a working model for phototoxicity and recommendations for its assessment.
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Affiliation(s)
- Rana A. Alghamdi
- Department of Chemistry, Science and Arts College, Rabigh Campus, King Abdulaziz University, Jeddah, Saudi Arabia
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Marino Exposito-Rodriguez
- School of Life Sciences, University of Essex, Colchester, United Kingdom
- Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom
| | | | - Greg N. Brooke
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Philippe P. Laissue
- School of Life Sciences, University of Essex, Colchester, United Kingdom
- *Correspondence: Philippe P. Laissue,
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7
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Hobson CM, Aaron JS, Heddleston JM, Chew TL. Visualizing the Invisible: Advanced Optical Microscopy as a Tool to Measure Biomechanical Forces. Front Cell Dev Biol 2021; 9:706126. [PMID: 34552926 PMCID: PMC8450411 DOI: 10.3389/fcell.2021.706126] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 08/09/2021] [Indexed: 01/28/2023] Open
Abstract
The importance of mechanical force in biology is evident across diverse length scales, ranging from tissue morphogenesis during embryo development to mechanotransduction across single adhesion proteins at the cell surface. Consequently, many force measurement techniques rely on optical microscopy to measure forces being applied by cells on their environment, to visualize specimen deformations due to external forces, or even to directly apply a physical perturbation to the sample via photoablation or optogenetic tools. Recent developments in advanced microscopy offer improved approaches to enhance spatiotemporal resolution, imaging depth, and sample viability. These advances can be coupled with already existing force measurement methods to improve sensitivity, duration and speed, amongst other parameters. However, gaining access to advanced microscopy instrumentation and the expertise necessary to extract meaningful insights from these techniques is an unavoidable hurdle. In this Live Cell Imaging special issue Review, we survey common microscopy-based force measurement techniques and examine how they can be bolstered by emerging microscopy methods. We further explore challenges related to the accompanying data analysis in biomechanical studies and discuss the various resources available to tackle the global issue of technology dissemination, an important avenue for biologists to gain access to pre-commercial instruments that can be leveraged for biomechanical studies.
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Affiliation(s)
- Chad M. Hobson
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - Jesse S. Aaron
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
| | - John M. Heddleston
- Cleveland Clinic Florida Research and Innovation Center, Port St. Lucie, FL, United States
| | - Teng-Leong Chew
- Advanced Imaging Center, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, United States
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9
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Emon MAB, Knoll S, Doha U, Ladehoff L, Lalonde L, Baietto D, Sivaguru M, Bhargava R, Saif MTA. Dose- independent threshold illumination for non-invasive time-lapse fluorescence imaging of live cells. Extreme Mech Lett 2021; 46:101249. [PMID: 34095408 PMCID: PMC8171180 DOI: 10.1016/j.eml.2021.101249] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Fluorescent microscopy employs monochromatic light for excitation, which can adversely affect the cells being observed. We reported earlier that fibroblasts relax their contractile force in response to green light of typical intensity. Here we show that such effects are independent of extracellular matrix and cell lines. In addition, we establish a threshold intensity that elicits minimal or no adverse effect on cell contractility even for long-time exposure. This threshold intensity is wavelength dependent. We cultured fibroblasts on soft 2D elastic hydrogels embedded with fluorescent beads to trace substrate deformation and cell forces. The beads move towards cell center when cells contract, but they move away when cells relax. We use relaxation/contraction ratio (λ r), in addition to traction force, as measures of cell response to red (wavelength, λ=635-650 nm), green (λ=545-580 nm) and blue (λ=455-490 nm) lights with varying intensities. Our results suggest that intensities below 57, 31 and 3.5 W/m2 for red, green and blue lights, respectively, do not perturb force homeostasis. To our knowledge, these intensities are the lowest reported safe thresholds, implying that cell traction is a highly sensitive readout of the effect of light on cells. Most importantly, we find these threshold intensities to be dose-independent; i.e., safe regardless of the energy dosage or time of exposure. Conversely, higher intensities result in widespread force-relaxation in cells with λ r > 1. Furthermore, we present a photo-reaction based model that simulates photo-toxicity and predicts threshold intensity for different wavelengths within the visible spectra. In conclusion, we recommend employing illumination intensities below aforementioned wavelength-specific thresholds for time-lapse imaging of cells and tissues in order to avoid light-induced artifacts in experimental observations.
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Affiliation(s)
- M A Bashar Emon
- Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign
| | - Samantha Knoll
- Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign
| | - Umnia Doha
- Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign
| | - Lauren Ladehoff
- Dept. of Bioengineering, University of Illinois at Urbana-Champaign
| | - Luke Lalonde
- Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign
| | - Danielle Baietto
- Dept. of Bioengineering, University of Illinois at Urbana-Champaign
| | - Mayandi Sivaguru
- Carle Woese Institute of Genomic Biology, University of Illinois at Urbana-Champaign
| | - Rohit Bhargava
- Dept. of Bioengineering, University of Illinois at Urbana-Champaign
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign
| | - M Taher A Saif
- Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign
- Dept. of Bioengineering, University of Illinois at Urbana-Champaign
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign
- Corresponding author: M Taher A Saif, Gutgsell Professor, Associate Head for Graduate Programs and Research, Mechanical Science and Engineering, Research Professor, Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, 2101D Mechanical Engineering Laboratory, 105 S. Mathews Avenue, Urbana, IL 61801, USA, , Tel: 217-333-8552, Fax: 217-244-6534, http://saif.mechse.illinois.edu/
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10
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Bouvrais H, Chesneau L, Le Cunff Y, Fairbrass D, Soler N, Pastezeur S, Pécot T, Kervrann C, Pécréaux J. The coordination of spindle-positioning forces during the asymmetric division of the Caenorhabditis elegans zygote. EMBO Rep 2021; 22:e50770. [PMID: 33900015 DOI: 10.15252/embr.202050770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 02/22/2021] [Accepted: 03/03/2021] [Indexed: 12/28/2022] Open
Abstract
In Caenorhabditis elegans zygote, astral microtubules generate forces essential to position the mitotic spindle, by pushing against and pulling from the cortex. Measuring microtubule dynamics there, we revealed the presence of two populations, corresponding to pulling and pushing events. It offers a unique opportunity to study, under physiological conditions, the variations of both spindle-positioning forces along space and time. We propose a threefold control of pulling force, by polarity, spindle position and mitotic progression. We showed that the sole anteroposterior asymmetry in dynein on-rate, encoding pulling force imbalance, is sufficient to cause posterior spindle displacement. The positional regulation, reflecting the number of microtubule contacts in the posterior-most region, reinforces this imbalance only in late anaphase. Furthermore, we exhibited the first direct proof that dynein processivity increases along mitosis. It reflects the temporal control of pulling forces, which strengthens at anaphase onset following mitotic progression and independently from chromatid separation. In contrast, the pushing force remains constant and symmetric and contributes to maintaining the spindle at the cell centre during metaphase.
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Affiliation(s)
| | | | - Yann Le Cunff
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Nina Soler
- CNRS, IGDR - UMR 6290, University of Rennes, Rennes, France
| | | | - Thierry Pécot
- INRIA, Centre Rennes - Bretagne Atlantique, Rennes, France
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11
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Belotti Y, Jokhun DS, Ponnambalam JS, Valerio VLM, Lim CT. Machine learning based approach to pH imaging and classification of single cancer cells. APL Bioeng 2021; 5:016105. [PMID: 33758789 PMCID: PMC7968934 DOI: 10.1063/5.0031615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/03/2021] [Indexed: 12/14/2022] Open
Abstract
The ability to identify different cell populations in a noninvasive manner and without the use of fluorescence labeling remains an important goal in biomedical research. Various techniques have been developed over the last decade, which mainly rely on fluorescent probes or nanoparticles. On the other hand, their applications to single-cell studies have been limited by the lengthy preparation and labeling protocols, as well as issues relating to reproducibility and sensitivity. Furthermore, some of these techniques require the cells to be fixed. Interestingly, it has been shown that different cell types exhibit a unique intracellular environment characterized by specific acidity conditions as a consequence of their distinct functions and metabolism. Here, we leverage a recently developed pH imaging modality and machine learning-based single-cell segmentation and classification to identify different cancer cell lines based on their characteristic intracellular pH. This simple method opens up the potential to perform rapid noninvasive identification of living cancer cells for early cancer diagnosis and further downstream analyses.
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Affiliation(s)
- Y Belotti
- Institute for Health Innovation and Technology, National University of Singapore, 117599 Singapore, Singapore
| | - D S Jokhun
- Department of Biomedical Engineering, National University of Singapore, 117583 Singapore, Singapore
| | - J S Ponnambalam
- Department of Biomedical Engineering, National University of Singapore, 117583 Singapore, Singapore
| | - V L M Valerio
- Department of Biomedical Engineering, National University of Singapore, 117583 Singapore, Singapore
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12
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Schmidt GW, Cuny AP, Rudolf F. Preventing Photomorbidity in Long-Term Multi-color Fluorescence Imaging of Saccharomyces cerevisiae and S. pombe. G3 (Bethesda) 2020; 10:4373-4385. [PMID: 33023973 PMCID: PMC7718758 DOI: 10.1534/g3.120.401465] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/06/2020] [Indexed: 12/16/2022]
Abstract
Time-lapse imaging of live cells using multiple fluorescent reporters is an essential tool to study molecular processes in single cells. However, exposure to even moderate doses of visible excitation light can disturb cellular physiology and alter the quantitative behavior of the cells under study. Here, we set out to develop guidelines to avoid the confounding effects of excitation light in multi-color long-term imaging. We use widefield fluorescence microscopy to measure the effect of the administered excitation light on growth rate (here called photomorbidity) in yeast. We find that photomorbidity is determined by the cumulative light dose at each wavelength, but independent of the way excitation light is applied. Importantly, photomorbidity possesses a threshold light dose below which no effect is detectable (NOEL). We found, that the suitability of fluorescent proteins for live-cell imaging at the respective excitation light NOEL is equally determined by the cellular autofluorescence and the fluorescent protein brightness. Last, we show that photomorbidity of multiple wavelengths is additive and imaging conditions absent of photomorbidity can be predicted. Our findings enable researchers to find imaging conditions with minimal impact on physiology and can provide framework for how to approach photomorbidity in other organisms.
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Affiliation(s)
- Gregor W Schmidt
- ETH Zurich, Department of Biosystems Science and Engineering, Mattenstrasse 26, 4058 Basel, Switzerland and
| | - Andreas P Cuny
- ETH Zurich, Department of Biosystems Science and Engineering, Mattenstrasse 26, 4058 Basel, Switzerland and
- SIB Swiss Institute of Bioinformatics, 4058 Basel, Switzerland
| | - Fabian Rudolf
- ETH Zurich, Department of Biosystems Science and Engineering, Mattenstrasse 26, 4058 Basel, Switzerland and
- SIB Swiss Institute of Bioinformatics, 4058 Basel, Switzerland
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13
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Abstract
The light (or optical) microscope is the icon of science. The aphorism "seeing is believing" is often quoted in scientific papers involving microscopy. Unlike many scientific instruments, the light microscope will deliver an image however badly it is set up. Fluorescence microscopy is a widely used research tool across all disciplines of biological and biomedical science. Most universities and research institutions have microscopes, including confocal microscopes. This introductory paper in a series detailing advanced light microscopy techniques explains the foundations of both electron and light microscopy for biologists and life scientists working with the mouse. An explanation is given of how an image is formed. A description is given of how to set up a light microscope, whether it be a brightfield light microscope on the laboratory bench, a widefield fluorescence microscope, or a confocal microscope. These explanations are accompanied by operational protocols. A full explanation on how to set up and adjust a microscope according to the principles of Köhler illumination is given. The importance of Nyquist sampling is discussed. Guidelines are given on how to choose the best microscope to image the particular sample or slide preparation that you are working with. These are the basic principles of microscopy that a researcher must have an understanding of when operating core bioimaging facility instruments, in order to collect high-quality images. © 2020 The Authors. Basic Protocol 1: Setting up Köhler illumination for a brightfield microscope Basic Protocol 2: Aligning the fluorescence bulb and setting up Köhler illumination for a widefield fluorescence microscope Basic Protocol 3: Generic protocol for operating a confocal microscope.
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Affiliation(s)
- Jeremy Sanderson
- Bioimaging Facility Manager, MRC Harwell Institute, Mammalian Genetics Unit, Harwell Campus, Oxfordshire, UK
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14
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Croft LV, Mulders JA, Richard DJ, O'Byrne K. Digital Holographic Imaging as a Method for Quantitative, Live Cell Imaging of Drug Response to Novel Targeted Cancer Therapies. Methods Mol Biol 2019; 2054:171-83. [PMID: 31482456 DOI: 10.1007/978-1-4939-9769-5_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Digital holographic imaging (DHI) is a noninvasive, live cell imaging technique that enables long-term quantitative visualization of cells in culture. DHI uses phase-shift imaging to monitor and quantify cellular events such as cell division, cell death, cell migration, and drug responses. In recent years, the application of DHI has expanded from its use in the laboratory to the clinical setting, and currently it is being developed for use in theranostics. Here, we describe the use of the DHI platform HoloMonitorM4 to evaluate the effects of novel, targeted cancer therapies on cell viability and proliferation using the HeLa cancer cell line as a model. We present single cell tracking and population-wide analysis of multiple cell morphology parameters.
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15
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Tosheva KL, Yuan Y, Matos Pereira P, Culley S, Henriques R. Between life and death: strategies to reduce phototoxicity in super-resolution microscopy. J Phys D Appl Phys 2020; 53:163001. [PMID: 33994582 PMCID: PMC8114953 DOI: 10.1088/1361-6463/ab6b95] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 11/01/2019] [Accepted: 01/14/2020] [Indexed: 05/23/2023]
Abstract
Super-resolution microscopy (SRM) enables non-invasive, molecule-specific imaging of the internal structure and dynamics of cells with sub-diffraction limit spatial resolution. One of its major limitations is the requirement for high-intensity illumination, generating considerable cellular phototoxicity. This factor considerably limits the capacity for live-cell observations, particularly for extended periods of time. Here, we give an overview of new developments in hardware, software and probe chemistry aiming to reduce phototoxicity. Additionally, we discuss how the choice of biological model and sample environment impacts the capacity for live-cell observations.
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Affiliation(s)
- Kalina L Tosheva
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Yue Yuan
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | | | - Siân Culley
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
| | - Ricardo Henriques
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
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16
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Abstract
What is the impact of cellular heterogeneity on process performance? How do individual cells contribute to averaged process productivity? Single-cell analysis is a key technology for answering such key questions of biotechnology, beyond bulky measurements with populations. The analysis of cellular individuality, its origins, and the dependency of process performance on cellular heterogeneity has tremendous potential for optimizing biotechnological processes in terms of metabolic, reaction, and process engineering. Microfluidics offer unmatched environmental control of the cellular environment and allow massively parallelized cultivation of single cells. However, the analytical accessibility to a cell's physiology is of crucial importance for obtaining the desired information on the single-cell production phenotype. Highly sensitive analytics are required to detect and quantify the minute amounts of target analytes and small physiological changes in a single cell. For their application to biotechnological questions, single-cell analytics must evolve toward the measurement of kinetics and specific rates of the smallest catalytic unit, the single cell. In this chapter, we focus on an introduction to the latest single-cell analytics and their application for obtaining physiological parameters in a biotechnological context from single cells. We present and discuss recent advancements in single-cell analytics that enable the analysis of cell-specific growth, uptake, and production kinetics, as well as the gene expression and regulatory mechanisms at a single-cell level.
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17
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Al-Gubory KH. Shedding light on fibered confocal fluorescence microscopy: Applications in biomedical imaging and therapies. J Biophotonics 2019; 12:e201900146. [PMID: 31343844 DOI: 10.1002/jbio.201900146] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 07/20/2019] [Accepted: 07/23/2019] [Indexed: 06/10/2023]
Abstract
Discoveries of major importance in life sciences and preclinical research are linked to the invention of microscopes that enable imaging of cells and their microstructures. Imaging technologies involving in vivo procedures using fluorescent dyes that permit labelling of cells have been developed over the last two decades. Fibered confocal fluorescence microscopy (FCFM) is an imaging technology equipped with fiber-optic probes to deliver light to organs and tissues of live animals. This enables not only in vivo detection of fluorescent signals and visualization of cells, but also the study of dynamic processes, such cell proliferation, apoptosis and angiogenesis, under physiological and pathological conditions. This will allow the diagnosis of diseased organs and tissues and the evaluation of the efficacy of new therapies in animal models of human diseases. The aim of this report is to shed light on FCFM and its potential medical applications and discusses some factors that compromise the reliability and reproducibility of monitoring biological processes by FCFM. This report also highlights the issues concerning animal experimentation and welfare, and the contributions of FCFM to the 3Rs principals, replacement, reduction and refinement.
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Affiliation(s)
- Kaïs H Al-Gubory
- National Institute for Agricultural Research, Department of Animal Physiology, Jouy-en-Josas, France
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18
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Yanakieva I, Matejčić M, Norden C. Choosing the right microscope to image mitosis in zebrafish embryos: A practical guide. Methods Cell Biol 2018; 145:107-27. [PMID: 29957200 DOI: 10.1016/bs.mcb.2018.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Tissue growth and organismal development require orchestrated cell proliferation. To understand how cell division guides development, it is important to explore mitosis at the tissue-wide, cellular, and subcellular scale. At the tissue level this includes determining a tissue's mitotic index, at the cellular level the tracing of cell lineages, and at the subcellular level the characterization of intracellular components. These different tasks can be addressed by different imaging approaches (e.g., laser-scanning confocal, spinning disk confocal, and light-sheet fluorescence microscopy). Here, we summarize three protocols for exploring different facets of mitosis in developing zebrafish embryos. Zebrafish embryos are transparent and their rapid external development greatly facilitates the study of cellular processes and developmental dynamics using microscopy. A critical step in all imaging studies of mitosis in development is to choose the most suitable microscope for each scientific question. This choice is important in order to ensure a balance between the required temporal and spatial resolution and minimal phototoxicity that could otherwise perturb the process of interest. The use of different microscopy techniques, best suited for the purpose of each experiment, thus permits to generate a comprehensive and unbiased view on how mitosis influences development.
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19
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Bouvrais H, Chesneau L, Pastezeur S, Fairbrass D, Delattre M, Pécréaux J. Microtubule Feedback and LET-99-Dependent Control of Pulling Forces Ensure Robust Spindle Position. Biophys J 2018; 115:2189-2205. [PMID: 30447992 PMCID: PMC6289040 DOI: 10.1016/j.bpj.2018.10.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 10/03/2018] [Accepted: 10/09/2018] [Indexed: 11/26/2022] Open
Abstract
During asymmetric division of the Caenorhabditis elegans zygote, to properly distribute cell fate determinants, the mitotic spindle is asymmetrically localized by a combination of centering and cortical-pulling microtubule-mediated forces, the dynamics of the latter being regulated by mitotic progression. Here, we show a, to our knowledge, novel and additional regulation of these forces by spindle position itself. For that, we observed the onset of transverse spindle oscillations, which reflects the burst of anaphase pulling forces. After delaying anaphase onset, we found that the position at which the spindle starts to oscillate was unchanged compared to control embryos and uncorrelated to anaphase onset. In mapping the cortical microtubule dynamics, we measured a steep increase in microtubule contact density after the posterior centrosome reached the critical position of 70% of embryo length, strongly suggesting the presence of a positional switch for spindle oscillations. Expanding a previous model based on a force-generator temporal control, we implemented this positional switch and observed that the large increase in microtubule density accounted for the pulling force burst. Thus, we propose that the spindle position influences the cortical availability of microtubules on which the active force generators, controlled by cell cycle progression, can pull. Importantly, we found that this positional control relies on the polarity-dependent LET-99 cortical band, the boundary of which could be probed by microtubules. This dual positional and temporal control well accounted for our observation that the oscillation onset position resists changes in cellular geometry and moderate variations in the active force generator number. Finally, our model suggests that spindle position at mitosis end is more sensitive to the polarity factor LET-99, which restricts the region of active force generators to a posterior-most region, than to microtubule number or force generator number/activity. Overall, we show that robustness in spindle positioning originates in cell mechanics rather than biochemical networks.
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Affiliation(s)
| | | | | | | | - Marie Delattre
- Univ Lyon, ENS de Lyon, Univ Claude Bernard, Laboratory of Biology and Modelling of the Cell, Lyon University, Lyon, France
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20
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Rigler R, Widengren J. Fluorescence-based monitoring of electronic state and ion exchange kinetics with FCS and related techniques: from T-jump measurements to fluorescence fluctuations. Eur Biophys J 2018; 47:479-492. [PMID: 29260269 PMCID: PMC5982452 DOI: 10.1007/s00249-017-1271-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 10/30/2017] [Accepted: 12/03/2017] [Indexed: 11/01/2022]
Abstract
In this review, we give a historical view of how our research in the development and use of fluorescence correlation spectroscopy (FCS) and related techniques has its roots and how it originally evolved from the pioneering work of Manfred Eigen, his colleagues, and coworkers. Work on temperature-jump (T-jump) experiments, conducted almost 50 years ago, led on to the development of the FCS technique. The pioneering work in the 1970s, introducing and demonstrating the concept for FCS, in turn formed the basis for the breakthrough use of FCS more than 15 years later. FCS can be used for monitoring reaction kinetics, based on fluctuations at thermodynamic equilibrium, rather than on relaxation measurements following perturbations. In this review, we more specifically discuss FCS measurements on photodynamic, electronic state transitions in fluorophore molecules, and on proton exchange dynamics in solution and on biomembranes. In the latter case, FCS measurements have proven capable of casting new light on the mechanisms of proton exchange at biological membranes, of central importance to bioenergetics and signal transduction. Finally, we describe the transient-state (TRAST) spectroscopy/imaging technique, sharing features with both relaxation (T-jump) and equilibrium fluctuation (FCS) techniques. TRAST is broadly applicable for cellular and molecular studies, and we briefly outline how TRAST can provide unique information from fluorophore blinking kinetics, reflecting e.g., cellular metabolism, rare molecular encounters, and molecular stoichiometries.
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Affiliation(s)
- Rudolf Rigler
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Jerker Widengren
- Experimental Biomolecular Physics/ Department of Applied Physics, Royal Institute of Technology (KTH), Stockholm, Sweden.
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21
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Aulner N, Danckaert A, Fernandes J, Nicola MA, Roux P, Salles A, Tinevez JY, Shorte SL. Fluorescence imaging host pathogen interactions: fifteen years benefit of hindsight…. Curr Opin Microbiol 2018; 43:193-198. [PMID: 29567588 DOI: 10.1016/j.mib.2018.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 03/01/2018] [Accepted: 03/02/2018] [Indexed: 01/24/2023]
Abstract
We consider in review current state-of-the-art fluorescence microscopy for investigating the host-pathogen interface. Our perspective is honed from years with literally thousands of microbiologists using the variety of imaging technologies available within our dedicated BSL2/BSL3 optical imaging research service facilities at the Institut Pasteur Paris founded from scratch in 2001. During fifteen years learning from the success and failures of introducing different fluorescence imaging technologies, methods, and technical development strategies we provide here a synopsis review of our experience to date and a synthesis of how we see the future in perspective for fluorescence imaging at the host-pathogen interface.
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Affiliation(s)
- Nathalie Aulner
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Anne Danckaert
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Julien Fernandes
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Marie-Anne Nicola
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Pascal Roux
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Audrey Salles
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Jean-Yves Tinevez
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Spencer L Shorte
- Institut Pasteur, Citech, Imagopole-UTechS-PBI Photonic BioImaging, 25-28 rue du Dr Roux, 75015 Paris, France
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22
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Abstract
Microbial single cell analysis has led to discoveries that are beyond what can be resolved with population-based studies. It provides a pristine view of the mechanisms that organize cellular physiology, unbiased by population heterogeneity or uncontrollable environmental impacts. A holistic description of cellular functions at the single cell level requires analytical concepts beyond the miniaturization of existing technologies, defined but uncontrolled by the biological system itself. This review provides an overview of the latest advances in single cell technologies and demonstrates their potential. Opportunities and limitations of single cell microbiology are discussed using selected application-related examples.
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Affiliation(s)
- Katrin Rosenthal
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
- Laboratory of Chemical Biotechnology, Department of Biochemical & Chemical Engineering, TU Dortmund University, Dortmund, Germany
| | - Verena Oehling
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
- Laboratory of Chemical Biotechnology, Department of Biochemical & Chemical Engineering, TU Dortmund University, Dortmund, Germany
| | - Christian Dusny
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
| | - Andreas Schmid
- Department Solar Materials, Helmholtz Centre for Environmental Research (UFZ), Leipzig, Germany
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23
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24
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Gregor I, Spiecker M, Petrovsky R, Großhans J, Ros R, Enderlein J. Rapid nonlinear image scanning microscopy. Nat Methods 2017; 14:1087-1089. [DOI: 10.1038/nmeth.4467] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 09/21/2017] [Indexed: 12/20/2022]
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25
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Hejna M, Jorapur A, Song JS, Judson RL. High accuracy label-free classification of single-cell kinetic states from holographic cytometry of human melanoma cells. Sci Rep 2017; 7:11943. [PMID: 28931937 PMCID: PMC5607248 DOI: 10.1038/s41598-017-12165-1] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/31/2017] [Indexed: 02/07/2023] Open
Abstract
Digital holographic cytometry (DHC) permits label-free visualization of adherent cells. Dozens of cellular features can be derived from segmentation of hologram-derived images. However, the accuracy of single cell classification by these features remains limited for most applications, and lack of standardization metrics has hindered independent experimental comparison and validation. Here we identify twenty-six DHC-derived features that provide biologically independent information across a variety of mammalian cell state transitions. When trained on these features, machine-learning algorithms achieve blind single cell classification with up to 95% accuracy. Using classification accuracy to guide platform optimization, we develop methods to standardize holograms for the purpose of kinetic single cell cytometry. Applying our approach to human melanoma cells treated with a panel of cancer therapeutics, we track dynamic changes in cellular behavior and cell state over time. We provide the methods and computational tools for optimizing DHC for kinetic single adherent cell classification.
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Affiliation(s)
- Miroslav Hejna
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL, 61801, USA.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W Gregory Dr., Urbana, IL, 61801, USA
| | - Aparna Jorapur
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, 1450 3rd Street, Box# 3111, San Francisco, CA, 94158, USA.,Department of Dermatology, University of California, San Francisco, 1701 Divisadero Street, San Francisco, CA, 94115, USA
| | - Jun S Song
- Department of Physics, University of Illinois at Urbana-Champaign, 1110 W Green St, Urbana, IL, 61801, USA. .,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 W Gregory Dr., Urbana, IL, 61801, USA.
| | - Robert L Judson
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, 1450 3rd Street, Box# 3111, San Francisco, CA, 94158, USA. .,Department of Dermatology, University of California, San Francisco, 1701 Divisadero Street, San Francisco, CA, 94115, USA.
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26
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Douthwright S, Sluder G. Live Cell Imaging: Assessing the Phototoxicity of 488 and 546 nm Light and Methods to Alleviate it. J Cell Physiol 2017; 232:2461-2468. [PMID: 27608139 DOI: 10.1002/jcp.25588] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 09/06/2016] [Indexed: 01/11/2023]
Abstract
In live cell imaging of fluorescent proteins, phototoxicity of the excitation light can be problematical. Cell death is obvious, but reduced cell viability can make the interpretation of observations error prone. We characterized the phototoxic consequences of 488 and 546 nm light on untransformed human cells and tested methods that have or could be used to alleviate photodamage. Unlabeled RPE1 cells were given single 0.5-2.5 min irradiations in early G1 from a mercury arc lamp on a fluorescence microscope. Four hundred eighty-eight nanometer light produced a dose-dependent decrease in the percentage of cells that progressed to mitosis, slowing of the cell cycle for some of those entering mitosis, and a ∼12% incidence of cell death for the highest dose. For 546 nm light we found a 10-15% reduction in the percentage of cells entering mitosis, no strong dose dependency, and a ∼2% incidence of cell death for the longest irradiations. For cells expressing GFP-centrin1 or mCherry-centrin1, fewer entered mitosis for each dose than unlabeled cells. For constant total dose 488 nm light irradiations of unlabeled cells, reducing the intensity 10-fold or spreading the exposures out as a series of 10 sec pulses at 1 min intervals produced a minor and not consistent improvement in the percentage of cells entering mitosis. Reducing oxidative processes, by culturing at ∼3% oxygen or adding the reducing agent Trolox noticeably increased the fraction of cells entering mitosis. Thus, for long-term imaging there can be value to using RFP constructs and for GFP-tagged proteins reducing oxidative processes. J. Cell. Physiol. 232: 2461-2468, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Stephen Douthwright
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Greenfield Sluder
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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27
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Abstract
Are the answers to biological questions obtained via live fluorescence microscopy substantially affected by phototoxicity? Although a single set of standards for assessing phototoxicity cannot exist owing to the breadth of samples and experimental questions associated with biological imaging, we need quantitative, practical assessments and reporting standards to ensure that imaging has a minimal impact on observed biological processes and sample health. Here we discuss the problem of phototoxicity in biology and suggest guidelines to improve its reporting and assessment.
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28
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Affiliation(s)
- Jaroslav Icha
- Max Planck Institute of Molecular Cell Biology and Genetics; Dresden; Germany
| | - Michael Weber
- Department of Cell Biology; Harvard Medical School; Boston MA USA
| | | | - Caren Norden
- Max Planck Institute of Molecular Cell Biology and Genetics; Dresden; Germany
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29
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Woringer M, Darzacq X, Zimmer C, Mir M. Faster and less phototoxic 3D fluorescence microscopy using a versatile compressed sensing scheme. Opt Express 2017; 25:13668-13683. [PMID: 28788909 PMCID: PMC5499637 DOI: 10.1364/oe.25.013668] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 05/16/2017] [Accepted: 05/19/2017] [Indexed: 05/25/2023]
Abstract
Three-dimensional fluorescence microscopy based on Nyquist sampling of focal planes faces harsh trade-offs between acquisition time, light exposure, and signal-to-noise. We propose a 3D compressed sensing approach that uses temporal modulation of the excitation intensity during axial stage sweeping and can be adapted to fluorescence microscopes without hardware modification. We describe implementations on a lattice light sheet microscope and an epifluorescence microscope, and show that images of beads and biological samples can be reconstructed with a 5-10 fold reduction of light exposure and acquisition time. Our scheme opens a new door towards faster and less damaging 3D fluorescence microscopy.
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30
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Stockley JH, Evans K, Matthey M, Volbracht K, Agathou S, Mukanowa J, Burrone J, Káradóttir RT. Surpassing light-induced cell damage in vitro with novel cell culture media. Sci Rep 2017; 7:849. [PMID: 28405003 DOI: 10.1038/s41598-017-00829-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 03/14/2017] [Indexed: 01/08/2023] Open
Abstract
Light is extensively used to study cells in real time (live cell imaging), separate cells using fluorescence activated cell sorting (FACS) and control cellular functions with light sensitive proteins (Optogenetics). However, photo-sensitive molecules inside cells and in standard cell culture media generate toxic by-products that interfere with cellular functions and cell viability when exposed to light. Here we show that primary cells from the rat central nervous system respond differently to photo-toxicity, in that astrocytes and microglia undergo morphological changes, while in developing neurons and oligodendrocyte progenitor cells (OPCs) it induces cellular death. To prevent photo-toxicity and to allow for long-term photo-stimulation without causing cellular damage, we formulated new photo-inert media called MEMO and NEUMO, and an antioxidant rich and serum free supplement called SOS. These new media reduced the detrimental effects caused by light and allowed cells to endure up to twenty times more light exposure without adverse effects, thus bypassing the optical constraints previously limiting experiments.
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31
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Abstract
Genetically encoded fluorescent tags are protein sequences that can be fused to a protein of interest to render it fluorescent. These tags have revolutionized cell biology by allowing nearly any protein to be imaged by light microscopy at submicrometer spatial resolution and subsecond time resolution in a live cell or organism. They can also be used to measure protein abundance in thousands to millions of cells using flow cytometry. Here I provide an introduction to the different genetic tags available, including both intrinsically fluorescent proteins and proteins that derive their fluorescence from binding of either endogenous or exogenous fluorophores. I discuss their optical and biological properties and guidelines for choosing appropriate tags for an experiment. Tools for tagging nucleic acid sequences and reporter molecules that detect the presence of different biomolecules are also briefly discussed.
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Affiliation(s)
- Kurt Thorn
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158
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32
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Kasprowicz R, Suman R, O'Toole P. Characterising live cell behaviour: Traditional label-free and quantitative phase imaging approaches. Int J Biochem Cell Biol 2017; 84:89-95. [PMID: 28111333 DOI: 10.1016/j.biocel.2017.01.004] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 12/23/2016] [Accepted: 01/06/2017] [Indexed: 01/01/2023]
Abstract
Label-free imaging uses inherent contrast mechanisms within cells to create image contrast without introducing dyes/labels, which may confound results. Quantitative phase imaging is label-free and offers higher content and contrast compared to traditional techniques. High-contrast images facilitate generation of individual cell metrics via more robust segmentation and tracking, enabling formation of a label-free dynamic phenotype describing cell-to-cell heterogeneity and temporal changes. Compared to population-level averages, individual cell-level dynamic phenotypes have greater power to differentiate between cellular responses to treatments, which has clinical relevance e.g. in the treatment of cancer. Furthermore, as the data is obtained label-free, the same cells can be used for further assays or expansion, of potential benefit for the fields of regenerative and personalised medicine.
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33
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Arena ET, Rueden CT, Hiner MC, Wang S, Yuan M, Eliceiri KW. Quantitating the cell: turning images into numbers with ImageJ. Wiley Interdiscip Rev Dev Biol 2016; 6. [PMID: 27911038 DOI: 10.1002/wdev.260] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 10/06/2016] [Accepted: 10/15/2016] [Indexed: 01/14/2023]
Abstract
Modern biological research particularly in the fields of developmental and cell biology has been transformed by the rapid evolution of the light microscope. The light microscope, long a mainstay of the experimental biologist, is now used for a wide array of biological experimental scenarios and sample types. Much of the great developments in advanced biological imaging have been driven by the digital imaging revolution with powerful processors and algorithms. In particular, this combination of advanced imaging and computational analysis has resulted in the drive of the modern biologist to not only visually inspect dynamic phenomena, but to quantify the involved processes. This need to quantitate images has become a major thrust within the bioimaging community and requires extensible and accessible image processing routines with corresponding intuitive software packages. Novel algorithms both made specifically for light microscopy or adapted from other fields, such as astronomy, are available to biologists, but often in a form that is inaccessible for a number of reasons ranging from data input issues, usability and training concerns, and accessibility and output limitations. The biological community has responded to this need by developing open source software packages that are freely available and provide access to image processing routines. One of the most prominent is the open-source image package ImageJ. In this review, we give an overview of prominent imaging processing approaches in ImageJ that we think are of particular interest for biological imaging and that illustrate the functionality of ImageJ and other open source image analysis software. WIREs Dev Biol 2017, 6:e260. doi: 10.1002/wdev.260 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Ellen T Arena
- Morgridge Institute for Research, Madison, WI, USA.,Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
| | - Curtis T Rueden
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
| | - Mark C Hiner
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
| | - Shulei Wang
- Department of Statistics, University of Wisconsin at Madison, Madison, WI, USA
| | - Ming Yuan
- Morgridge Institute for Research, Madison, WI, USA.,Department of Statistics, University of Wisconsin at Madison, Madison, WI, USA
| | - Kevin W Eliceiri
- Morgridge Institute for Research, Madison, WI, USA.,Laboratory for Optical and Computational Instrumentation, University of Wisconsin at Madison, Madison, WI, USA
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Tinevez JY, Perry N, Schindelin J, Hoopes GM, Reynolds GD, Laplantine E, Bednarek SY, Shorte SL, Eliceiri KW. TrackMate: An open and extensible platform for single-particle tracking. Methods 2016; 115:80-90. [PMID: 27713081 DOI: 10.1016/j.ymeth.2016.09.016] [Citation(s) in RCA: 1605] [Impact Index Per Article: 200.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 09/29/2016] [Accepted: 09/30/2016] [Indexed: 01/12/2023] Open
Abstract
We present TrackMate, an open source Fiji plugin for the automated, semi-automated, and manual tracking of single-particles. It offers a versatile and modular solution that works out of the box for end users, through a simple and intuitive user interface. It is also easily scriptable and adaptable, operating equally well on 1D over time, 2D over time, 3D over time, or other single and multi-channel image variants. TrackMate provides several visualization and analysis tools that aid in assessing the relevance of results. The utility of TrackMate is further enhanced through its ability to be readily customized to meet specific tracking problems. TrackMate is an extensible platform where developers can easily write their own detection, particle linking, visualization or analysis algorithms within the TrackMate environment. This evolving framework provides researchers with the opportunity to quickly develop and optimize new algorithms based on existing TrackMate modules without the need of having to write de novo user interfaces, including visualization, analysis and exporting tools. The current capabilities of TrackMate are presented in the context of three different biological problems. First, we perform Caenorhabditis-elegans lineage analysis to assess how light-induced damage during imaging impairs its early development. Our TrackMate-based lineage analysis indicates the lack of a cell-specific light-sensitive mechanism. Second, we investigate the recruitment of NEMO (NF-κB essential modulator) clusters in fibroblasts after stimulation by the cytokine IL-1 and show that photodamage can generate artifacts in the shape of TrackMate characterized movements that confuse motility analysis. Finally, we validate the use of TrackMate for quantitative lifetime analysis of clathrin-mediated endocytosis in plant cells.
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Affiliation(s)
| | - Nick Perry
- Imagopole, Citech, Institut Pasteur, 75724 Paris, France
| | - Johannes Schindelin
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Genevieve M Hoopes
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Gregory D Reynolds
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Emmanuel Laplantine
- Laboratory of Signaling and Pathogenesis, Centre National de la Recherche Scientifique, UMR 3691, Institut Pasteur, 75724 Paris, France
| | - Sebastian Y Bednarek
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | - Kevin W Eliceiri
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI 53706, USA; Morgridge Institute for Research, Madison, WI 53719, USA
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35
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Abstract
Many questions in developmental biology depend on measuring the position and movement of individual cells within developing embryos. Yet, tools that provide this data are often challenged by high cell density and their accuracy is difficult to measure. Here, we present a three-step procedure to address this problem. Step one is a novel segmentation algorithm based on image derivatives that, in combination with selective post-processing, reliably and automatically segments cell nuclei from images of densely packed tissue. Step two is a quantitative validation using synthetic images to ascertain the efficiency of the algorithm with respect to signal-to-noise ratio and object density. Finally, we propose an original method to generate reliable and experimentally faithful ground truth datasets: Sparse-dense dual-labeled embryo chimeras are used to unambiguously measure segmentation errors within experimental data. Together, the three steps outlined here establish a robust, iterative procedure to fine-tune image analysis algorithms and microscopy settings associated with embryonic 3D image data sets.
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Affiliation(s)
- Bhavna Rajasekaran
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Koichiro Uriu
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
- Theoretical Biology Laboratory, RIKEN, Saitama, Japan
| | - Guillaume Valentin
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- MRC-National Institute for Medical Research, London, United Kingdom
| | - Jean-Yves Tinevez
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Andrew C. Oates
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- MRC-National Institute for Medical Research, London, United Kingdom
- Department of Cell and Developmental Biology, University College, London, United Kingdom
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Abstract
Proximity enhancement is a central chemical tenet underpinning an exciting suite of small-molecule toolsets that have allowed us to unravel many biological complexities. The leitmotif of this opus is "tethering"-a strategy in which a multifunctional small molecule serves as a template to bring proteins/biomolecules together. Scaffolding approaches have been powerfully applied to control diverse biological outcomes such as protein-protein association, protein stability, activity, and improve imaging capabilities. A new twist on this strategy has recently appeared, in which the small-molecule probe is engineered to unleash controlled amounts of reactive chemical signals within the microenvironment of a target protein. Modification of a specific target elicits a precisely timed and spatially controlled gain-of-function (or dominant loss-of-function) signaling response. Presented herein is a unique personal outlook conceptualizing the powerful proximity-enhanced chemical biology toolsets into two paradigms: "multifunctional scaffolding" versus "on-demand targeting". By addressing the latest advances and challenges in the established yet constantly evolving multifunctional scaffolding strategies as well as in the emerging on-demand precision targeting (and related) systems, this Perspective is aimed at choosing when it is best to employ each of the two strategies, with an emphasis toward further promoting novel applications and discoveries stemming from these innovative chemical biology platforms.
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Affiliation(s)
- Marcus
J. C. Long
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
| | - Jesse R. Poganik
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
| | - Yimon Aye
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
- Department
of Biochemistry, Weill Cornell Medicine, New York, New York 10065, United States
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37
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Abstract
Live cell imaging is a valuable technique that allows the characterization of the dynamic processes of the HIV-1 life cycle. Here, we present a method of production and imaging of dual-labeled HIV viral particles that allows the visualization of two events. Varying release of the intravirion fluid phase marker reveals virion fusion and the loss of the integrity of HIV viral cores with the use of live wide-field fluorescent microscopy.
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Affiliation(s)
- João I Mamede
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E. Superior, Lurie 9-280, Chicago, IL, 60611, USA
| | - Thomas J Hope
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E. Superior, Lurie 9-280, Chicago, IL, 60611, USA.
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Caron J, Fallet C, Tinevez JY, Moisan L, Braitbart LPO, Sirat GY, Shorte SL. Conical diffraction illumination opens the way for low phototoxicity super-resolution imaging. Cell Adh Migr 2015; 8:430-9. [PMID: 25482642 PMCID: PMC4594584 DOI: 10.4161/cam.29358] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We present a new technology for super-resolution fluorescence imaging, based on conical diffraction. Conical diffraction is a linear, singular phenomenon, taking place when a laser beam is diffracted through a biaxial crystal. We use conical diffraction in a thin biaxial crystal to generate illumination patterns that are more compact than the classical Gaussian beam, and use them to generate a super-resolution imaging modality. While there already exist several super-resolution modalities, our technology (biaxial super-resolution: BSR) is distinguished by the unique combination of several performance features. Using BSR super-resolution data are achieved using low light illumination significantly less than required for classical confocal imaging, which makes BSR ideal for live-cell, long-term time-lapse super-resolution imaging. Furthermore, no specific sample preparation is required, and any fluorophore can be used. Perhaps most exciting, improved resolution BSR-imaging resolution enhancement can be achieved with any type of objective no matter the magnification, numerical aperture, working distance, or the absence or presence of immersion medium. In this article, we present the first implementation of BSR modality on a commercial confocal microscope. We acquire and analyze validation data, showing high quality super-resolved images of biological objects, and demonstrate the wide applicability of the technology. We report live-cell super-resolution imaging over a long period, and show that the light dose required for super-resolution imaging is far below the threshold likely to generate phototoxicity.
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Georgantzoglou A, Merchant MJ, Jeynes JCG, Wéra AC, Kirkby KJ, Kirkby NF, Jena R. Automatic cell detection in bright-field microscopy for microbeam irradiation studies. Phys Med Biol 2015; 60:6289-303. [PMID: 26236995 DOI: 10.1088/0031-9155/60/16/6289] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Automatic cell detection in bright-field illumination microscopy is challenging due to cells' inherent optical properties. Applications including individual cell microbeam irradiation demand minimisation of additional cell stressing factors, so contrast-enhancing fluorescence microscopy should be avoided. Additionally, the use of optically non-homogeneous substrates amplifies the problem. This research focuses on the design of a method for automatic cell detection on polypropylene substrate, suitable for microbeam irradiation. In order to fulfil the relative requirements, the Harris corner detector was employed to detect apparent cellular features. These features-corners were clustered based on a dual-clustering technique according to the density of their distribution across the image. Weighted centroids were extracted from the clusters of corners and constituted the targets for irradiation. The proposed method identified more than 88% of the 1,738 V79 Chinese hamster cells examined. Moreover, a processing time of 2.6 s per image fulfilled the requirements for a near real-time cell detection-irradiation system.
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Affiliation(s)
- A Georgantzoglou
- Department of Oncology, Addenbrooke's Hospital, Hills Road, University of Cambridge, Cambridgeshire, CB2 0QQ, UK
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40
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Galli R, Uckermann O, Andresen EF, Geiger KD, Koch E, Schackert G, Steiner G, Kirsch M. Intrinsic indicator of photodamage during label-free multiphoton microscopy of cells and tissues. PLoS One 2014; 9:e110295. [PMID: 25343251 PMCID: PMC4208781 DOI: 10.1371/journal.pone.0110295] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 09/11/2014] [Indexed: 12/04/2022] Open
Abstract
Multiphoton imaging has evolved as an indispensable tool in cell biology and holds prospects for clinical applications. When addressing endogenous signals such as coherent anti-Stokes Raman scattering (CARS) or second harmonic generation, it requires intense laser irradiation that may cause photodamage. We report that increasing endogenous fluorescence signal upon multiphoton imaging constitutes a marker of photodamage. The effect was studied on mouse brain in vivo and ex vivo, on ex vivo human brain tissue samples, as well as on glioblastoma cells in vitro, demonstrating that this phenomenon is common to a variety of different systems, both ex vivo and in vivo. CARS microscopy and vibrational spectroscopy were used to analyze the photodamage. The development of a standard easy-to-use model that employs rehydrated cryosections allowed the characterization of the irradiation-induced fluorescence and related it to nonlinear photodamage. In conclusion, the monitoring of endogenous two-photon excited fluorescence during label-free multiphoton microscopy enables to estimate damage thresholds ex vivo as well as detect photodamage during in vivo experiments.
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Affiliation(s)
- Roberta Galli
- Clinical Sensoring and Monitoring, Anesthesiology and Intensive Care Medicine, Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Ortrud Uckermann
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
| | - Elisabeth F. Andresen
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
- CRTD/DFG-Center for Regenerative Therapies Dresden - Cluster of Excellence, Dresden, Germany
| | - Kathrin D. Geiger
- Neuropathology, Institute for Pathology, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
| | - Edmund Koch
- Clinical Sensoring and Monitoring, Anesthesiology and Intensive Care Medicine, Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Gabriele Schackert
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
| | - Gerald Steiner
- Clinical Sensoring and Monitoring, Anesthesiology and Intensive Care Medicine, Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Matthias Kirsch
- Neurosurgery, Carl Gustav Carus University Hospital, TU Dresden, Dresden, Germany
- CRTD/DFG-Center for Regenerative Therapies Dresden - Cluster of Excellence, Dresden, Germany
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41
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Stewart RS, Kiss IM, Wilkinson RS. Visualization of endosome dynamics in living nerve terminals with four-dimensional fluorescence imaging. J Vis Exp 2014. [PMID: 24799002 DOI: 10.3791/51477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Four-dimensional (4D) light imaging has been used to study behavior of small structures within motor nerve terminals of the thin transversus abdominis muscle of the garter snake. Raw data comprises time-lapse sequences of 3D z-stacks. Each stack contains 4-20 images acquired with epifluorescence optics at focal planes separated by 400-1,500 nm. Steps in the acquisition of image stacks, such as adjustment of focus, switching of excitation wavelengths, and operation of the digital camera, are automated as much as possible to maximize image rate and minimize tissue damage from light exposure. After acquisition, a set of image stacks is deconvolved to improve spatial resolution, converted to the desired 3D format, and used to create a 4D "movie" that is suitable for variety of computer-based analyses, depending upon the experimental data sought. One application is study of the dynamic behavior of two classes of endosomes found in nerve terminals-macroendosomes (MEs) and acidic endosomes (AEs)-whose sizes (200-800 nm for both types) are at or near the diffraction limit. Access to 3D information at each time point provides several advantages over conventional time-lapse imaging. In particular, size and velocity of movement of structures can be quantified over time without loss of sharp focus. Examples of data from 4D imaging reveal that MEs approach the plasma membrane and disappear, suggesting that they are exocytosed rather than simply moving vertically away from a single plane of focus. Also revealed is putative fusion of MEs and AEs, by visualization of overlap between the two dye-containing structures as viewed in each three orthogonal projections.
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Affiliation(s)
- Richard S Stewart
- Department of Cell Biology and Physiology, Washington University School of Medicine
| | - Ilona M Kiss
- Department of Cell Biology and Physiology, Washington University School of Medicine
| | - Robert S Wilkinson
- Department of Cell Biology and Physiology, Washington University School of Medicine;
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42
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Tournebize R, Dragavon J, Miller AD, Shorte S. Silencing the radicals improves Click Chemistry. Biotechnol J 2014; 9:595-6. [PMID: 24737539 DOI: 10.1002/biot.201400103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Modern fluorescence imaging microscopy in living and fixed material makes use of fluorescent probes to label targeted entities. Common labelling approaches include classical immunocytochemistry, expression of chimerically tagged fluorescent protein domains, and chemical affinity-binding or covalent labelling. Of these methods, the so-called "Click Chemistry", is emerging as one of the most influential labelling chemistries introduced in recent times, offering enormous utility for bio-orthoganol attachment of fluorescent probes to biological target entities. In this issue of Biotechnology Journal, Löschberger, Niehörster and Sauer report "ClickOx", a Click Chemistry protocol that uses an enzymatic oxygen scavenger system to reduce concurrent ROS-associated damage during Click labeling.
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Affiliation(s)
- Régis Tournebize
- Institut Pasteur, Imagopole, Plateforme d'imagerie dynamique, Paris, France; INSERM U786, Paris, France
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43
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Askjaer P, Galy V, Meister P. Modern Tools to Study Nuclear Pore Complexes and Nucleocytoplasmic Transport in Caenorhabditis elegans. Methods Cell Biol 2014; 122:277-310. [DOI: 10.1016/b978-0-12-417160-2.00013-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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44
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Abstract
Communication between cells and their environment, including other cells, is often mediated by cell surface receptors. Fluorescence methodologies are among the most important techniques used to study receptors and their interactions, and in the past decade, fluorescence fluctuation spectroscopy (FFS) approaches have been increasingly utilized. In this overview, we illustrate how diverse FFS approaches have been used to elucidate important aspects of receptor systems, including interactions of receptors with their ligands and receptor oligomerization and clustering. We also describe the most popular methods used to introduce fluorescent moieties into the biological systems. Finally, specific attention will be given to cell maintenance and transfection strategies especially as related to microscopy studies.
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Affiliation(s)
- David M Jameson
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
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45
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Guenot M, Racz P. Practical course on "imaging infection: from single molecules to animals". Microbes Infect 2012; 14:1475-82. [PMID: 23128379 DOI: 10.1016/j.micinf.2012.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 10/01/2012] [Accepted: 10/02/2012] [Indexed: 11/16/2022]
Abstract
A 2-week long theoretical and practical course on innovative microscopy in the field of microbial infection was organized in Pretoria, South Africa. Talks from lecturers from such fields as super-resolution microscopy, fluorescence and bioluminescence imaging, high throughput microscopy assays and image analysis were followed by practicals on cutting-edge microscopes.
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Affiliation(s)
- Marianne Guenot
- Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5164, 33000 Bordeaux, France.
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