scholarly journals POLArIS, a versatile probe for molecular orientation, revealed actin filaments associated with microtubule asters in early embryos

2020 ◽  
Author(s):  
Ayana Sugizaki ◽  
Keisuke Sato ◽  
Kazuyoshi Chiba ◽  
Kenta Saito ◽  
Masahiko Kawagishi ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Molecular Orientation ◽  
Fluorescent Protein ◽  
Three Dimensional ◽  
Super Resolution ◽  
Living Cells ◽  
Test Case ◽  
Polarization Microscopy ◽  
Universal Method ◽  
Early Embryos

AbstractBiomolecular assemblies govern the physiology of cells. Their function often depends on the changes in molecular arrangements of constituents, both in the positions and orientations. While recent advancements of fluorescence microscopy including super-resolution microscopy have enabled us to determine the positions of fluorophores with unprecedented accuracy, monitoring orientation of fluorescently labeled molecules within living cells in real-time is challenging. Fluorescence polarization microscopy (FPM) reports the orientation of emission dipoles and is therefore a promising solution. For imaging with FPM, target proteins need labeling with fluorescent probes in a sterically constrained manner, but due to difficulties in the rational three-dimensional design of protein connection, universal method for constrained tagging with fluorophore was not available. Here we report POLArIS, a genetically encoded and versatile probe for molecular orientation imaging. Instead of using a direct tagging approach, we used a recombinant binder connected to a fluorescent protein in a sterically constrained manner and can target arbitrary biomolecules by combining with phage-display screening. As an initial test case of POLArIS, we developed POLArISact, which specifically binds to F-actin in living cells. We confirmed that the orientation of F-actin can be monitored by observing cells expressing POLArISact with FPM. In living starfish early embryos expressing POLArISact, we found actin filaments radially extending from centrosomes in association with microtubule asters during mitosis. By taking advantage of the genetically encoded nature, POLArIS can be used in a variety of living specimens including whole bodies of developing embryos and animals, and also expressed in a cell-type/tissue specific manner.

scholarly journals POLArIS, a versatile probe for molecular orientation, revealed actin filaments associated with microtubule asters in early embryos

2021 ◽  
Vol 118 (11) ◽  
pp. e2019071118
Author(s):  
Ayana Sugizaki ◽  
Keisuke Sato ◽  
Kazuyoshi Chiba ◽  
Kenta Saito ◽  
Masahiko Kawagishi ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Molecular Orientation ◽  
Fluorescent Protein ◽  
Three Dimensional ◽  
Super Resolution ◽  
Living Cells ◽  
Test Case ◽  
Polarization Microscopy ◽  
Universal Method ◽  
Early Embryos

Biomolecular assemblies govern the physiology of cells. Their function often depends on the changes in molecular arrangements of constituents, both in the positions and orientations. While recent advancements of fluorescence microscopy including super-resolution microscopy have enabled us to determine the positions of fluorophores with unprecedented accuracy, monitoring the orientation of fluorescently labeled molecules within living cells in real time is challenging. Fluorescence polarization microscopy (FPM) reports the orientation of emission dipoles and is therefore a promising solution. For imaging with FPM, target proteins need labeling with fluorescent probes in a sterically constrained manner, but because of difficulties in the rational three-dimensional design of protein connection, a universal method for constrained tagging with fluorophore was not available. Here, we report POLArIS, a genetically encoded and versatile probe for molecular orientation imaging. Instead of using a direct tagging approach, we used a recombinant binder connected to a fluorescent protein in a sterically constrained manner that can target specific biomolecules of interest by combining with phage display screening. As an initial test case, we developed POLArISact, which specifically binds to F-actin in living cells. We confirmed that the orientation of F-actin can be monitored by observing cells expressing POLArISact with FPM. In living starfish early embryos expressing POLArISact, we found actin filaments radially extending from centrosomes in association with microtubule asters during mitosis. By taking advantage of the genetically encoded nature, POLArIS can be used in a variety of living specimens, including whole bodies of developing embryos and animals, and also be expressed in a cell type/tissue specific manner.

Modulated polarization microscopy displays the dynamics of cytoskeletal structures in living, motile cells

1995 ◽  
Vol 53 ◽  
pp. 902-903
Author(s):  
J. R. Kuhn ◽  
M. Poenie
Keyword(s):  
Mitotic Spindle ◽  
Actin Filaments ◽  
Cell Shape ◽  
Dynamic Structure ◽  
Living Cells ◽  
Cytoskeletal Proteins ◽  
Polarization Microscopy ◽  
Video Enhancement ◽  
Ultrastructural Studies ◽  
Motile Cells

Cell shape and movement are controlled by elements of the cytoskeleton including actin filaments an microtubules. Unfortunately, it is difficult to visualize the cytoskeleton in living cells and hence follow it dynamics. Immunofluorescence and ultrastructural studies of fixed cells while providing clear images of the cytoskeleton, give only a static picture of this dynamic structure. Microinjection of fluorescently Is beled cytoskeletal proteins has proved useful as a way to follow some cytoskeletal events, but long terry studies are generally limited by the bleaching of fluorophores and presence of unassembled monomers.Polarization microscopy has the potential for visualizing the cytoskeleton. Although at present, it ha mainly been used for visualizing the mitotic spindle. Polarization microscopy is attractive in that it pro vides a way to selectively image structures such as cytoskeletal filaments that are birefringent. By combing ing standard polarization microscopy with video enhancement techniques it has been possible to image single filaments. In this case, however, filament intensity depends on the orientation of the polarizer and analyzer with respect to the specimen.

scholarly journals Super-resolution imaging of fluorescent dipoles via polarized structured illumination microscopy

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Karl Zhanghao ◽  
Xingye Chen ◽  
Wenhui Liu ◽  
Meiqi Li ◽  
Yiqiong Liu ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Fluorescent Protein ◽  
Imaging Modality ◽  
Super Resolution ◽  
Vital Role ◽  
Molecular Structures ◽  
Polarization Microscopy ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Resolution Imaging

Abstract Fluorescence polarization microscopy images both the intensity and orientation of fluorescent dipoles and plays a vital role in studying molecular structures and dynamics of bio-complexes. However, current techniques remain difficult to resolve the dipole assemblies on subcellular structures and their dynamics in living cells at super-resolution level. Here we report polarized structured illumination microscopy (pSIM), which achieves super-resolution imaging of dipoles by interpreting the dipoles in spatio-angular hyperspace. We demonstrate the application of pSIM on a series of biological filamentous systems, such as cytoskeleton networks and λ-DNA, and report the dynamics of short actin sliding across a myosin-coated surface. Further, pSIM reveals the side-by-side organization of the actin ring structures in the membrane-associated periodic skeleton of hippocampal neurons and images the dipole dynamics of green fluorescent protein-labeled microtubules in live U2OS cells. pSIM applies directly to a large variety of commercial and home-built SIM systems with various imaging modality.

scholarly journals Super-Resolution Imaging by Dual Iterative Structured Illumination Microscopy

2021 ◽  
Author(s):  
Anna Loeschberger ◽  
Yauheni Novikau ◽  
Ralf Netz ◽  
Marie-Christin Spindler ◽  
Ricardo Benavente ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Brain Slices ◽  
Super Resolution ◽  
Reconstruction Algorithm ◽  
Living Cells ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Spatiotemporal Resolution ◽  
Coated Pits ◽  
Resolution Imaging

Three-dimensional (3D) multicolor super-resolution imaging in the 50-100 nm range in fixed and living cells remains challenging. We extend the resolution of structured illumination microscopy (SIM) by an improved nonlinear iterative reconstruction algorithm that enables 3D multicolor imaging with improved spatiotemporal resolution at low illumination intensities. We demonstrate the performance of dual iterative SIM (diSIM) imaging cellular structures in fixed cells including synaptonemal complexes, clathrin coated pits and the actin cytoskeleton with lateral resolutions of 60-100 nm with standard fluorophores. Furthermore, we visualize dendritic spines in 70 micrometer thick brain slices with an axial resolution < 200 nm. Finally, we image dynamics of the endoplasmatic reticulum and microtubules in living cells with up to 255 frames/s.

scholarly journals Adaptive optics allows 3D STED-FCS measurements in the cytoplasm of living cells

2019 ◽  
Author(s):  
Aurélien Barbotin ◽  
Silvia Galiani ◽  
Iztok Urbančič ◽  
Christian Eggeling ◽  
Martin Booth
Keyword(s):  
Adaptive Optics ◽  
Molecular Diffusion ◽  
Three Dimensional ◽  
Super Resolution ◽  
Correction Method ◽  
Living Cells ◽  
Correlation Spectroscopy ◽  
Stimulated Emission ◽  
Optical Aberrations ◽  
Extreme Sensitivity

Fluorescence correlation spectroscopy in combination with super-resolution stimulated emission depletion microscopy (STED-FCS) is a powerful tool to investigate molecular diffusion with sub-diffraction resolution. It has been of particular use for investigations of two dimensional systems like cell membranes, but has so far seen very limited applications to studies of three-dimensional diffusion. One reason for this is the extreme sensitivity of the axial (3D) STED depletion pattern to optical aberrations. We present here an adaptive optics-based correction method that compensates for these aberrations and allows STED-FCS measurements in the cytoplasm of living cells.

scholarly journals Connexin-specific distribution within gap junctions revealed in living cells

2000 ◽  
Vol 113 (22) ◽  
pp. 4109-4120 ◽  
Author(s):  
M.M. Falk
Keyword(s):  
High Resolution ◽  
Gap Junctions ◽  
Gap Junction ◽  
Fluorescent Protein ◽  
Three Dimensional ◽  
Time Lapse ◽  
Living Cells ◽  
Dye Transfer ◽  
Channel Distribution ◽  
Specific Distribution

To study the organization of gap junctions in living cells, the connexin isotypes alpha(1)(Cx43), beta(1)(Cx32) and beta(2)(Cx26) were tagged with the autofluorescent tracer green fluorescent protein (GFP) and its cyan (CFP) and yellow (YFP) color variants. The cellular fate of the tagged connexins was followed by high-resolution fluorescence deconvolution microscopy and time-lapse imaging. Comprehensive analyses demonstrated that the tagged channels were functional as monitored by dye transfer, even under conditions where the channels were assembled solely from tagged connexins. High-resolution images revealed a detailed structural organization, and volume reconstructions provided a three-dimensional view of entire gap junction plaques. Specifically, deconvolved dual-color images of gap junction plaques assembled from CFP- and YFP-tagged connexins revealed that different connexin isotypes gathered within the same plaques. Connexins either codistributed homogeneously throughout the plaque, or each connexin isotype segregated into well-separated domains. The studies demonstrate that the mode of channel distribution strictly depends on the connexin isotypes. Based on previous studies on the synthesis and assembly of connexins I suggest that channel distribution is regulated by intrinsic connexin isotype specific signals.

scholarly journals Super-resolution microscopy reveals the three-dimensional organization of meiotic chromosome axes in intact C. elegans tissue

2017 ◽  
Author(s):  
Simone Köhler ◽  
Michal Wojcik ◽  
Ke Xu ◽  
Abby F. Dernburg
Keyword(s):  
Fluorescent Protein ◽  
Meiotic Chromosome ◽  
Three Dimensional ◽  
Super Resolution ◽  
Molecular Organization ◽  
Central Plane ◽  
Strand Breaks ◽  
Superresolution Imaging ◽  
C Elegans ◽  
Specific Proteins

AbstractWhen cells enter meiosis, their chromosomes reorganize as linear arrays of chromatin loops anchored to a central axis. Meiotic chromosome axes form a platform for the assembly of the synaptonemal complex (SC), and play central roles in other meiotic processes, including homologous pairing, recombination, and chromosome segregation. However, little is known about the three-dimensional organization of components within the axes, which consist of cohesin complexes and additional meiosis-specific proteins. Here we investigate the molecular organization of meiotic chromosome axes in C. elegans through STORM and PALM superresolution imaging of intact germline tissue. By tagging one axis protein (HIM-3) with a photoconvertible fluorescent protein, we established a spatial reference for other components, which were localized using antibodies against epitope tags inserted by CRISPR/Cas9 genome editing. Using three-dimensional averaging, we determined the 3D-organization of all known components within synapsed chromosome axes to a precision of 2-5 nanometers. We find that meiosis-specific HORMA-domain proteins span a gap between cohesin complexes and the central region of the SC, consistent with their essential roles in SC assembly. Our data further suggest that the two different meiotic cohesin complexes are distinctly arranged within the axes: Cohesin complexes containing COH-3 or -4 kleisins form a central core in the central plane of the axes, whereas complexes containing REC-8 kleisin protrude above and below the plane defined by the SC. This splayed organization may help to explain the role of the chromosome axes in promoting inter-homolog repair of meiotic double strand breaks by inhibiting inter-sister repair.

scholarly journals Fluorescent Protein-Based Indicators for Functional Super-Resolution Imaging of Biomolecular Activities in Living Cells

2019 ◽  
Vol 20 (22) ◽  
pp. 5784 ◽  
Author(s):  
Kai Lu ◽  
Cong Quang Vu ◽  
Tomoki Matsuda ◽  
Takeharu Nagai
Keyword(s):  
Image Analysis ◽  
Light Microscopy ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Super Resolution ◽  
Living Cells ◽  
Bimolecular Fluorescence Complementation ◽  
Analysis Pipeline ◽  
Nanoscale Topography ◽  
Resolution Imaging

Super-resolution light microscopy (SRM) offers a unique opportunity for diffraction-unlimited imaging of biomolecular activities in living cells. To realize such potential, genetically encoded indicators were developed recently from fluorescent proteins (FPs) that exhibit phototransformation behaviors including photoactivation, photoconversion, and photoswitching, etc. Super-resolution observations of biomolecule interactions and biochemical activities have been demonstrated by exploiting the principles of bimolecular fluorescence complementation (BiFC), points accumulation for imaging nanoscale topography (PAINT), and fluorescence fluctuation increase by contact (FLINC), etc. To improve functional nanoscopy with the technology of genetically encoded indicators, it is essential to fully decipher the photo-induced chemistry of FPs and opt for innovative indicator designs that utilize not only fluorescence intensity but also multi-parametric readouts such as phototransformation kinetics. In parallel, technical improvements to both the microscopy optics and image analysis pipeline are promising avenues to increase the sensitivity and versatility of functional SRM.

Super-Resolution Three-Dimensional Imaging of Actin Filaments in Cultured Cells and the Brain via Expansion Microscopy

ACS Nano ◽  
2020 ◽  
Vol 14 (11) ◽  
pp. 14999-15010
Author(s):  
Chan E Park ◽  
Youngbin Cho ◽  
In Cho ◽  
Hyunsu Jung ◽  
Byeongyeon Kim ◽  
...  
Keyword(s):  
Actin Filaments ◽  
Cultured Cells ◽  
Three Dimensional ◽  
Super Resolution ◽  
Three Dimensional Imaging ◽  
The Brain

scholarly journals Single-molecule spectroscopy and imaging over the decades

2015 ◽  
Vol 184 ◽  
pp. 9-36 ◽  
Author(s):  
W. E. Moerner ◽  
Yoav Shechtman ◽  
Quan Wang
Keyword(s):  
Single Molecule ◽  
Optical Switching ◽  
Fluorescent Protein ◽  
Single Molecules ◽  
Three Dimensional ◽  
Super Resolution ◽  
Laser Frequency ◽  
High Resolution Spectroscopy ◽  
Focal Volume ◽  
Ensemble Averaging

As of 2015, it has been 26 years since the first optical detection and spectroscopy of single molecules in condensed matter. This area of science has expanded far beyond the early low temperature studies in crystals to include single molecules in cells, polymers, and in solution. The early steps relied upon high-resolution spectroscopy of inhomogeneously broadened optical absorption profiles of molecular impurities in solids at low temperatures. Spectral fine structure arising directly from the position-dependent fluctuations of the number of molecules in resonance led to the attainment of the single-molecule limit in 1989 using frequency-modulation laser spectroscopy. In the early 1990s, a variety of fascinating physical effects were observed for individual molecules, including imaging of the light from single molecules as well as observations of spectral diffusion, optical switching and the ability to select different single molecules in the same focal volume simply by tuning the pumping laser frequency. In the room temperature regime, researchers showed that bursts of light from single molecules could be detected in solution, leading to imaging and microscopy by a variety of methods. Studies of single copies of the green fluorescent protein also uncovered surprises, especially the blinking and photoinduced recovery of emitters, which stimulated further development of photoswitchable fluorescent protein labels. All of these early steps provided important fundamentals underpinning the development of super-resolution microscopy based on single-molecule localization and active control of emitting concentration. Current thrust areas include extensions to three-dimensional imaging with high precision, orientational analysis of single molecules, and direct measurements of photodynamics and transport properties for single molecules trapped in solution by suppression of Brownian motion. Without question, a huge variety of studies of single molecules performed by many talented scientists all over the world have extended our knowledge of the nanoscale and many microscopic mechanisms previously hidden by ensemble averaging.

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