Existing super-resolution fluorescence microscopes compromise acquisition speed to provide subdiffractive sample information. We report an analog implementation of structured illumination microscopy ...that enables three-dimensional (3D) super-resolution imaging with a lateral resolution of 145 nm and an axial resolution of 350 nm at acquisition speeds up to 100 Hz. By using optical instead of digital image-processing operations, we removed the need to capture, store and combine multiple camera exposures, increasing data acquisition rates 10- to 100-fold over other super-resolution microscopes and acquiring and displaying super-resolution images in real time. Low excitation intensities allow imaging over hundreds of 2D sections, and combined physical and computational sectioning allow similar depth penetration to spinning-disk confocal microscopy. We demonstrate the capability of our system by imaging fine, rapidly moving structures including motor-driven organelles in human lung fibroblasts and the cytoskeleton of flowing blood cells within developing zebrafish embryos.
Multifocal structured illumination microscopy (MSIM) provides a twofold resolution enhancement beyond the diffraction limit at sample depths up to 50 µm, but scattered and out-of-focus light in thick ...samples degrades MSIM performance. Here we implement MSIM with a microlens array to enable efficient two-photon excitation. Two-photon MSIM gives resolution-doubled images with better sectioning and contrast in thick scattering samples such as Caenorhabditis elegans embryos, Drosophila melanogaster larval salivary glands, and mouse liver tissue.
We review two cases of adolescents with orbital cellulitis, sinusitis and SARS- CoV-2 infection presenting to emergency departments within a 24 hour period. SARS-CoV-2 samples obtained within ...24 hours were positive, supporting prior infection despite relatively limited early symptoms of COVID-19. Unusual clinical and radiographic characteristics included hemorrhagic abscess with blood of varying age in the first, intracranial epidural abscess in the second, radiographic signal consistent with hemorrhagic or thrombotic phenomena, retro-maxillary antral fat changes, and meningeal enhancement or extension in both cases. Radiographic findings thereby mimic fungal infection, although final cultures and ancillary investigation for allergic and invasive fungal disease have remained negative. These cases highlight two unusual orbital presentations of cellulitis occurring in the context of SARS-CoV-2 co-infection.
Reassortment of influenza viral RNA (vRNA) segments in co-infected cells can lead to the emergence of viruses with pandemic potential. Replication of influenza vRNA occurs in the nucleus of infected ...cells, while progeny virions bud from the plasma membrane. However, the intracellular mechanics of vRNA assembly into progeny virions is not well understood. Here we used recent advances in microscopy to explore vRNA assembly and transport during a productive infection. We visualized four distinct vRNA segments within a single cell using fluorescent in situ hybridization (FISH) and observed that foci containing more than one vRNA segment were found at the external nuclear periphery, suggesting that vRNA segments are not exported to the cytoplasm individually. Although many cytoplasmic foci contain multiple vRNA segments, not all vRNA species are present in every focus, indicating that assembly of all eight vRNA segments does not occur prior to export from the nucleus. To extend the observations made in fixed cells, we used a virus that encodes GFP fused to the viral polymerase acidic (PA) protein (WSN PA-GFP) to explore the dynamics of vRNA assembly in live cells during a productive infection. Since WSN PA-GFP colocalizes with viral nucleoprotein and influenza vRNA segments, we used it as a surrogate for visualizing vRNA transport in 3D and at high speed by inverted selective-plane illumination microscopy. We observed cytoplasmic PA-GFP foci colocalizing and traveling together en route to the plasma membrane. Our data strongly support a model in which vRNA segments are exported from the nucleus as complexes that assemble en route to the plasma membrane through dynamic colocalization events in the cytoplasm.
Sporulation in the bacterium Bacillus subtilis is a developmental program in which a progenitor cell differentiates into two different cell types, the smaller of which eventually becomes a dormant ...cell called a spore. The process begins with an asymmetric cell division event, followed by the activation of a transcription factor, σF, specifically in the smaller cell. Here, we show that the structural protein DivIVA localizes to the polar septum during sporulation and is required for asymmetric division and the compartment-specific activation of σF. Both events are known to require a protein called SpoIIE, which also localizes to the polar septum. We show that DivIVA copurifies with SpoIIE and that DivIVA may anchor SpoIIE briefly to the assembling polar septum before SpoIIE is subsequently released into the forespore membrane and recaptured at the polar septum. Finally, using super-resolution microscopy, we demonstrate that DivIVA and SpoIIE ultimately display a biased localization on the side of the polar septum that faces the smaller compartment in which σF is activated.
To report a novel case of unilateral peripheral facial nerve palsy manifesting as a complication of Herpes simplex keratitis.
A 51-year-old immunocompetent male presented with severe eye pain for 3 ...weeks. He was found to have Herpes simplex keratitis in the left eye and started on valacyclovir 3g per day for 10 days. At three weeks his pain and blurred vision resolved. He returned 2.5 months later with worsening of vision and five days of unilateral facial numbness and weakness. Ocular evaluation revealed a visual acuity of 20/25 in the left eye, which showed mid-stromal corneal edema bordered by several keratoprecipitates. Both the keratitis and Bell's palsy markedly improved with valacyclovir, topical prednisolone, and a 10-day course of oral prednisone.
This is the first reported case of Bell's palsy accompanying disciform keratitis. Both entities have been observed to be caused by Herpes simplex, however they have not been described together in one patient. Knowledge that these conditions may present simultaneously allows for earlier identification and treatment, resulting in decreased morbidity.
Optimal four-dimensional imaging requires high spatial resolution in all dimensions, high speed and minimal photobleaching and damage. We developed a dual-view, plane illumination microscope with ...improved spatiotemporal resolution by switching illumination and detection between two perpendicular objectives in an alternating duty cycle. Computationally fusing the resulting volumetric views provides an isotropic resolution of 330 nm. As the sample is stationary and only two views are required, we achieve an imaging speed of 200 images/s (i.e., 0.5 s for a 50-plane volume). Unlike spinning-disk confocal or Bessel beam methods, which illuminate the sample outside the focal plane, we maintain high spatiotemporal resolution over hundreds of volumes with negligible photobleaching. To illustrate the ability of our method to study biological systems that require high-speed volumetric visualization and/or low photobleaching, we describe microtubule tracking in live cells, nuclear imaging over 14 h during nematode embryogenesis and imaging of neural wiring during Caenorhabditis elegans brain development over 5 h.
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