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6 Publications

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    11/15/18 | Visualizing intracellular organelle and cytoskeletal interactions at nanoscale resolution on millisecond timescales.
    Guo Y, Li D, Zhang S, Yang Y, Liu J, Wang X, Liu C, Milkie DE, Moore RP, Tulu US, Kiehart DP, Hu J, Lippincott-Schwartz J, Betzig E, Li D
    Cell. 2018 Nov 15;175(5):1430-42. doi: 10.1016/j.cell.2018.09.057

    In eukaryotic cells, organelles and the cytoskeleton undergo highly dynamic yet organized interactions capable of orchestrating complex cellular functions. Visualizing these interactions requires noninvasive, long-duration imaging of the intracellular environment at high spatiotemporal resolution and low background. To achieve these normally opposing goals, we developed grazing incidence structured illumination microscopy (GI-SIM) that is capable of imaging dynamic events near the basal cell cortex at 97-nm resolution and 266 frames/s over thousands of time points. We employed multi-color GI-SIM to characterize the fast dynamic interactions of diverse organelles and the cytoskeleton, shedding new light on the complex behaviors of these structures. Precise measurements of microtubule growth or shrinkage events helped distinguish among models of microtubule dynamic instability. Analysis of endoplasmic reticulum (ER) interactions with other organelles or microtubules uncovered new ER remodeling mechanisms, such as hitchhiking of the ER on motile organelles. Finally, ER-mitochondria contact sites were found to promote both mitochondrial fission and fusion.

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    09/06/18 | 4D cell biology: big data image analytics and lattice light-sheet imaging reveal dynamics of clathrin-mediated endocytosis in stem cell derived intestinal organoids.
    Schöneberg J, Dambournet D, Liu T, Forster R, Hockemeyer D, Betzig E, Drubin DG
    Molecular Biology of the Cell. 2018 Sep 06:mbcE18060375. doi: 10.1091/mbc.E18-06-0375

    New methods in stem cell 3D organoid tissue culture, advanced imaging and big data image analytics now allow tissue scale 4D cell biology, but currently available analytical pipelines are inadequate for handing and analyzing the resulting gigabytes and terabytes of high-content imaging data. We expressed fluorescent protein fusions of clathrin and dynamin2 at endogenous levels in genome-edited human embryonic stem cells, which were differentiated into hESC-derived intestinal epithelial organoids. Lattice Light-Sheet Imaging with adaptive optics (AO-LLSM) allowed us to image large volumes of these organoids (70µm x 60µm x 40µm xyz) at 5.7s/frame. We developed an open source data analysis package termed pyLattice to process the resulting large (∼60Gb) movie datasets and to track clathrin-mediated endocytosis (CME) events. CME tracks could be recorded from ∼35 cells at a time, resulting in ∼4000 processed tracks per movie. Based on their localization in the organoid, we classified CME tracks into apical, lateral and basal events and found that CME dynamics are similar for all three classes, despite reported differences in membrane tension. pyLattice coupled with AO-LLSM makes possible quantitative, high temporal and spatial resolution analysis of subcellular events within tissues. Movie S1 Movie S1 Thresholded 3D AO-LLSM data of an intestinal epithelial organoid showing clathrin (red) and dynamin2 (green) puncta in surface depiction. The movie zooms out from a single clathrin mediated endocytosis event that shows both clathrin and dynamin2 at the same location to eventually show the whole AO-LLSM field of view. Nuclear envelopes and the outer membranes of the tissue are depicted in transparent white. Movie S2 Movie S2 Thresholded 3D AO-LLSM data of an intestinal epithelial organoid showing clathrin (red) and dynamin2 (green) puncta in surface depiction. The movie rotates the AO-LLSM field of view. Nuclear envelopes and the outer membranes of the tissue are depicted in transparent white. Movie S3 Movie S3 Thresholded 3D AO-LLSM data of an intestinal epithelial organoid. The curved surface is of the spherical organoid is visible as the movie rotates. Clathrin puncta are visible throughout the tissue (white). Movie S4 Movie S4 The detection step in the data processing pipeline retrieves all clathrin puncta in the volume. Detected puncta are marked with a cube (blue). Movie S5 Movie S5 Zoom on one clathrin puncta in the thresholded 3D dataset. The punctum of interest is marked with a blue cube. Other puncta are also visible. Movie S6 Movie S6 Zoom on the same clathrin puncta as in M3 in non-thresholded 3D data. The surrounding fluorescence is visible as a transparent cloud.

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    07/12/18 | A complete electron microscopy volume of the brain of adult Drosophila melanogaster.
    Zheng Z, Lauritzen JS, Perlman E, Robinson CG, Nichols M, Milkie DE, Torrens O, Price J, Fisher CB, Sharifi N, Calle-Schuler SA, Kmecova L, Ali IJ, Karsh B, Trautman ET, Bogovic JA, Hanslovsky P, Jefferis GS, Kazhdan M, Khairy K
    Cell. 2018 Jul 12;174(3):730-43. doi: 10.1016/j.cell.2018.06.019

    Drosophila melanogaster has a rich repertoire of innate and learned behaviors. Its 100,000-neuron brain is a large but tractable target for comprehensive neural circuit mapping. Only electron microscopy (EM) enables complete, unbiased mapping of synaptic connectivity; however, the fly brain is too large for conventional EM. We developed a custom high-throughput EM platform and imaged the entire brain of an adult female fly at synaptic resolution. To validate the dataset, we traced brain-spanning circuitry involving the mushroom body (MB), which has been extensively studied for its role in learning. All inputs to Kenyon cells (KCs), the intrinsic neurons of the MB, were mapped, revealing a previously unknown cell type, postsynaptic partners of KC dendrites, and unexpected clustering of olfactory projection neurons. These reconstructions show that this freely available EM volume supports mapping of brain-spanning circuits, which will significantly accelerate Drosophila neuroscience..

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    06/19/18 | Lamellar junctions in the endolymphatic sac act as a relief valve to regulate inner ear pressure.
    Ian A. Swinburne , Kishore R. Mosaliganti , Srigokul Upadhyayula , Tsung-Li Liu , David G. C. Hildebrand , Tony Y.-C. Tsai , Anzhi Chen , Ebaa Al-Obeidi , Anna K. Fass , Samir Malhotra , Florian Engert , Jeff W. Lichtman , Tom Kirchhausen , Sean G. Megason , Eric Betzig
    eLife. 2018 Jun 19:. doi: 10.7554/eLife.37131
    06/19/18 | Lamellar projections in the endolymphatic sac act as a relief valve to regulate inner ear pressure.
    Swinburne IA, Mosaliganti KR, Upadhyayula S, Liu T, Hildebrand DG, Tsai TY, Chen A, Al-Obeidi E, Fass AK, Malhotra S, Engert F, Lichtman JW, Kirchausen T, Betzig E, Megason SG
    eLife. 2018 Jun 19;7:. doi: 10.7554/eLife.37131

    The inner ear is a fluid-filled closed-epithelial structure whose function requires maintenance of an internal hydrostatic pressure and fluid composition. The endolymphatic sac (ES) is a dead-end epithelial tube connected to the inner ear whose function is unclear. ES defects can cause distended ear tissue, a pathology often seen in hearing and balance disorders. Using live imaging of zebrafish larvae, we reveal that the ES undergoes cycles of slow pressure-driven inflation followed by rapid deflation. Absence of these cycles in mutants leads to distended ear tissue. Using serial-section electron microscopy and adaptive optics lattice light-sheet microscopy, we find a pressure relief valve in the ES comprised of partially separated apical junctions and dynamic overlapping basal lamellae that separate under pressure to release fluid. We propose that this lmx1-dependent pressure relief valve is required to maintain fluid homeostasis in the inner ear and other fluid-filled cavities.

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    04/20/18 | Observing the cell in its native state: Imaging subcellular dynamics in multicellular organisms.
    Liu T, Upadhyayula S, Milkie DE, Singh V, Wang K, Swinburne IA, Mosaliganti KR, Collins ZM, Hiscock TW, Shea J, Kohrman AQ, Medwig TN, Dambournet D, Forster R, Cunniff B, Ruan Y, Yashiro H, Scholpp S, Meyerowitz EM, Hockemeyer D, Drubin DG, Martin BL, Matus DQ, Koyama M, Megason SG, Kirchhausen T, Betzig E
    Science (New York, N.Y.). 2018 Apr 20;360(6386):. doi: 10.1126/science.aaq1392

    True physiological imaging of subcellular dynamics requires studying cells within their parent organisms, where all the environmental cues that drive gene expression, and hence the phenotypes that we actually observe, are present. A complete understanding also requires volumetric imaging of the cell and its surroundings at high spatiotemporal resolution, without inducing undue stress on either. We combined lattice light-sheet microscopy with adaptive optics to achieve, across large multicellular volumes, noninvasive aberration-free imaging of subcellular processes, including endocytosis, organelle remodeling during mitosis, and the migration of axons, immune cells, and metastatic cancer cells in vivo. The technology reveals the phenotypic diversity within cells across different organisms and developmental stages and may offer insights into how cells harness their intrinsic variability to adapt to different physiological environments.

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