Biophysical Society Thematic Meeting| Lima 2019

Revisiting the Central Dogma of Molecular Biology at the Single-Molecule Level

Friday Speaker Abstracts

IMAGING SUBCELLULAR DYNAMICS FROM MOLECULES TO MULTICELLULAR ORGANISMS Tomas Kirchhausen ; 1 Harvard Medical School, Cell Biology, Boston, MA, USA

Frontier optical-imaging modalities exemplified by the lattice light-sheet microscope invented by Eric Betzig sets new visualization standards for analyzing and understanding sub-cellular processes in the complex and dynamic three-dimensional environment of living-cells in isolation and within tissues of an organism. By using ultra-thin sheets of light to rapidly illuminate biological samples with extremely low photon doses, 3D experiments previously limited to seconds or minutes by photo-bleaching or by photo- toxicity, can now be done at diffraction limited resolution and high-temporal precision with unprecedented duration of minutes or hours. We believe this ability to image with minimal perturbations is ideally suited to support hypothesis-generating research geared towards new discoveries. The talk will illustrate our use of lattice light-sheet microscopy to ‘see’ in three dimensions processes that mediate and regulate the biogenesis of organelles in living cells maintained in tissue culture conditions and will also describe our most recent efforts using lattice light sheet microscopy with adaptive optics to investigate with subcellular precision process in cells within tissues of a living zebrafish embryo.

SUPER-RESOLUTION IMAGING OF CHROMATIN ORGANIZATION Melike Lakadamyali ; 1 University of Pennsylvania, Physiology, Philadelphia, PA, USA

Nucleosomes help structure chromosomes by compacting DNA into fibers. Chromatin organization plays an important role for regulating gene expression; however, due to the nanometer length scales involved, it has been very difficult to visualize chromatin fibers in vivo. Using super-resolution microscopy, quantitative analysis and simulations, we have been gaining new insights into chromatin organization at nanometer length scales in intact nuclei. For example, we found that nucleosomes assemble into heterogeneous groups of varying sizes, which we named “clutches,” in analogy with “egg clutches”. Clutch organization is highly cell specific and i will give various examples of this specificity. Overall, our results reveal how the chromatin fiber is formed at nanoscale level and link chromatin fiber architecture to cell state.

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