scholarly journals Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading

Science ◽  
2021 ◽  
Vol 372 (6547) ◽  
pp. eabe7500
Author(s):  
Lisa Rodermund ◽  
Heather Coker ◽  
Roel Oldenkamp ◽  
Guifeng Wei ◽  
Joseph Bowness ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Super Resolution ◽  
Feedback Mechanism ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Time Resolved ◽  
Rna Molecules ◽  
Fundamental Parameters ◽  
Xist Rna ◽  
Key Factor

X-inactive specific transcript (Xist) RNA directs the process of X chromosome inactivation in mammals by spreading in cis along the chromosome from which it is transcribed and recruiting chromatin modifiers to silence gene transcription. To elucidate mechanisms of Xist RNA cis-confinement, we established a sequential dual-color labeling, super-resolution imaging approach to trace individual Xist RNA molecules over time, which enabled us to define fundamental parameters of spreading. We demonstrate a feedback mechanism linking Xist RNA synthesis and degradation and an unexpected physical coupling between preceding and newly synthesized Xist RNA molecules. Additionally, we find that the protein SPEN, a key factor for Xist-mediated gene silencing, has a distinct function in Xist RNA localization, stability, and coupling behaviors. Our results provide insights toward understanding the distinct dynamic properties of Xist RNA.

scholarly journals Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading

2020 ◽  
Author(s):  
Lisa Rodermund ◽  
Heather Coker ◽  
Roel Oldenkamp ◽  
Guifeng Wei ◽  
Joseph Bowness ◽  
...  
Keyword(s):  
X Chromosome ◽  
Dynamic Properties ◽  
Single Cells ◽  
Super Resolution ◽  
X Chromosome Inactivation ◽  
Chromosome Inactivation ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Rna Molecules ◽  
Xist Rna

AbstractXist RNA directs the process of X-chromosome inactivation in mammals by spreading in cis along the chromosome from which it is transcribed and recruiting chromatin modifiers to silence gene transcription. To elucidate mechanisms of Xist RNA cis-confinement, we established a sequential dual color labeling, super-resolution imaging approach to trace individual Xist RNA molecules over time, enabling us to define fundamental parameters of spreading. We demonstrate a feedback mechanism linking Xist RNA synthesis and degradation, and an unexpected physical coupling between preceding and newly synthesized Xist RNA molecules. Additionally, we show that the protein SPEN, a key factor for Xist-mediated gene-silencing, has a distinct function in Xist RNA localization, stability and in coupling behavior. Our results provide important insights towards understanding the unique dynamic properties of Xist RNA.One Sentence SummaryVisualizing Xist RNA dynamics in single cells during X chromosome inactivation

scholarly journals Mitochondrial RNA granules are fluid condensates, positioned by membrane dynamics

2019 ◽  
Author(s):  
Timo Rey ◽  
Sofia Zaganelli ◽  
Emilie Cuillery ◽  
Jean-Claude Martinou ◽  
Suliana Manley
Keyword(s):  
Dynamic Properties ◽  
Mitochondrial Fission ◽  
Super Resolution ◽  
Membrane Dynamics ◽  
Cellular Respiration ◽  
Mitochondrial Rna ◽  
Structured Illumination ◽  
Inner Mitochondrial Membrane ◽  
Structured Illumination Microscopy ◽  
Rna Granules

Mitochondria contain the genetic information and expression machinery to produce proteins essential for cellular respiration. Within the mitochondrial matrix, newly synthesized RNA, RNA processing proteins, and mitoribosome assembly factors are known to form punctate subcompartments referred to as mitochondrial RNA granules (MRGs) 1–3. Despite their proposed role in regulating gene expression, little is known about the structural and dynamic properties of MRGs. We investigated the organization of MRGs using fluorescence super-resolution localization microscopy and correlative electron microscopy techniques, obtaining ultrastructural details of their internal architecture. We find that MRGs are organized into nanoscale RNA cores surrounded by a protein shell. Using live-cell super-resolution structured illumination microscopy and photobleaching perturbations, we reveal that MRGs undergo fusion and rapidly exchange components, consistent with liquid-liquid phase separation (LLPS). Furthermore, MRGs associate with the inner mitochondrial membrane and their fusion coincides with membrane remodeling. Inhibition of mitochondrial fission leads to an aberrant distribution of MRGs into concentrated pockets, where they remain as distinct individual units despite their close apposition. Together, our results reveal a role for LLPS in concentrating RNA and its processing proteins into MRGs, which are positioned along mitochondria by membrane dynamics.

scholarly journals Two-dimensional TIRF-SIM–traction force microscopy (2D TIRF-SIM-TFM)

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Liliana Barbieri ◽  
Huw Colin-York ◽  
Kseniya Korobchevskaya ◽  
Di Li ◽  
Deanna L. Wolfson ◽  
...  
Keyword(s):  
Resolution Enhancement ◽  
Traction Force ◽  
Super Resolution ◽  
Traction Force Microscopy ◽  
Two Dimensional ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Force Microscopy ◽  
Health And Disease ◽  
Spatio Temporal

AbstractQuantifying small, rapidly evolving forces generated by cells is a major challenge for the understanding of biomechanics and mechanobiology in health and disease. Traction force microscopy remains one of the most broadly applied force probing technologies but typically restricts itself to slow events over seconds and micron-scale displacements. Here, we improve >2-fold spatially and >10-fold temporally the resolution of planar cellular force probing compared to its related conventional modalities by combining fast two-dimensional total internal reflection fluorescence super-resolution structured illumination microscopy and traction force microscopy. This live-cell 2D TIRF-SIM-TFM methodology offers a combination of spatio-temporal resolution enhancement relevant to forces on the nano- and sub-second scales, opening up new aspects of mechanobiology to analysis.

scholarly journals Double moiré localized plasmon structured illumination microscopy

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ruslan Röhrich ◽  
A. Femius Koenderink
Keyword(s):  
Near Field ◽  
Super Resolution ◽  
Reconstruction Algorithm ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Experimental Realization ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Localized Plasmon ◽  
Plasmonic Grating

AbstractStructured illumination microscopy (SIM) is a well-established fluorescence imaging technique, which can increase spatial resolution by up to a factor of two. This article reports on a new way to extend the capabilities of structured illumination microscopy, by combining ideas from the fields of illumination engineering and nanophotonics. In this technique, plasmonic arrays of hexagonal symmetry are illuminated by two obliquely incident beams originating from a single laser. The resulting interference between the light grating and plasmonic grating creates a wide range of spatial frequencies above the microscope passband, while still preserving the spatial frequencies of regular SIM. To systematically investigate this technique and to contrast it with regular SIM and localized plasmon SIM, we implement a rigorous simulation procedure, which simulates the near-field illumination of the plasmonic grating and uses it in the subsequent forward imaging model. The inverse problem, of obtaining a super-resolution (SR) image from multiple low-resolution images, is solved using a numerical reconstruction algorithm while the obtained resolution is quantitatively assessed. The results point at the possibility of resolution enhancements beyond regular SIM, which rapidly vanishes with the height above the grating. In an initial experimental realization, the existence of the expected spatial frequencies is shown and the performance of compatible reconstruction approaches is compared. Finally, we discuss the obstacles of experimental implementations that would need to be overcome for artifact-free SR imaging.

scholarly journals High-fidelity structured illumination microscopy by point-spread-function engineering

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Gang Wen ◽  
Simin Li ◽  
Linbo Wang ◽  
Xiaohu Chen ◽  
Zhenglong Sun ◽  
...  
Keyword(s):  
Point Spread Function ◽  
Super Resolution ◽  
Reconstruction Algorithm ◽  
High Fidelity ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Imaging Tool ◽  
Point Spread ◽  
Spread Function ◽  
Point Spread Function Engineering

AbstractStructured illumination microscopy (SIM) has become a widely used tool for insight into biomedical challenges due to its rapid, long-term, and super-resolution (SR) imaging. However, artifacts that often appear in SIM images have long brought into question its fidelity, and might cause misinterpretation of biological structures. We present HiFi-SIM, a high-fidelity SIM reconstruction algorithm, by engineering the effective point spread function (PSF) into an ideal form. HiFi-SIM can effectively reduce commonly seen artifacts without loss of fine structures and improve the axial sectioning for samples with strong background. In particular, HiFi-SIM is not sensitive to the commonly used PSF and reconstruction parameters; hence, it lowers the requirements for dedicated PSF calibration and complicated parameter adjustment, thus promoting SIM as a daily imaging tool.

The FDTD Analysis of Near-Field Response for Microgroove Structure With Standing Wave Illumination for the Realization of Coherent Structured Illumination Microscopy

2021 ◽  
Author(s):  
Yizhao Guan ◽  
Hiromasa Kume ◽  
Shotaro Kadoya ◽  
Masaki Michihata ◽  
Satoru Takahashi
Keyword(s):  
Standing Wave ◽  
Incident Angle ◽  
Near Field ◽  
Super Resolution ◽  
Structured Illumination ◽  
Field Phase ◽  
Structured Illumination Microscopy ◽  
Depth Measurement ◽  
Field Response ◽  
Depth Dependency

Abstract Microstructures are widely used in the manufacture of functional surfaces. An optical-based super-resolution, non-invasive method is preferred for the inspection of surfaces with massive microstructures. The Structured Illumination Microscopy (SIM) uses standing-wave illumination to reach optical super-resolution. Recently, coherent SIM is being studied. It can obtain not only the super-resolved intensity distribution but also the phase and amplitude distribution of the sample surface beyond the diffraction limit. By analysis of the phase-depth dependency, the depth measurement for microgroove structures with coherent SIM is expected. FDTD analysis is applied for observing the near-field response of microgroove under the standing-wave illumination. The near-field phase shows depth dependency in this analysis. Moreover, the effects from microgroove width, the incident angle, and the relative position between the standing-wave peak and center of the microgroove are investigated. It is found the near-field phase change can measure depth until 200 nm (aspect ratio 1) with an error of up to 20.4 nm in the case that the microgroove width is smaller than half of the wavelength.

Super-Resolution Imaging in Fluid Mechanics Using New Illumination Approaches

2020 ◽  
Vol 52 (1) ◽  
pp. 369-393
Author(s):  
Minami Yoda
Keyword(s):  
Fluid Mechanics ◽  
Total Internal Reflection ◽  
Imaging Techniques ◽  
Super Resolution ◽  
Internal Reflection ◽  
Interfacial Flows ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Entire Volume ◽  
Resolution Imaging

Quantifying submillimeter flows using optical diagnostic techniques is often limited by a lack of spatial resolution and optical access. This review discusses two super-resolution imaging techniques, structured illumination microscopy and total internal reflection fluorescence or microscopy, which can visualize bulk and interfacial flows, respectively, at spatial resolutions below the classic diffraction limits. First, we discuss the theory and applications of structured illumination for optical sectioning, i.e., imaging a thin slice of a flow illuminated over its entire volume. Structured illumination can be used to visualize the interior of multiphase flows such as sprays by greatly reducing secondary scattering. Second, the theory underlying evanescent waves is introduced, followed by a review of how total internal reflection microscopy has been used to visualize interfacial flows over the last 15 years. Both techniques, which are starting to be used in fluid mechanics, could significantly improve quantitative imaging of microscale and macroscale flows.

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