Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 15: Postersession III

BP 15.26: Poster

Dienstag, 13. März 2018, 14:00–16:00, Poster B

X-ray Imaging of DNA Compaction During the Cell Cycle — •Andrew Wittmeier, Mareike Töpperwien, Clément Hémonnot, and Sarah Köster — Institute for X-ray Physics, Göttingen, Germany.

Imaging nanoscale structures within a cell presents several challenges. Visible light imaging techniques, such as phase contrast or fluorescence microscopy, can image living cells but they cannot access the nanoscale, with the exception of super-resolution techniques. Electron microscopy can access nanometer length scales but at the expense of detrimental sample preparation methods, e.g. staining and slicing the cell. To overcome these limitations, we combine complementary methods and employ imaging techniques involving X-rays: their high energies allow for high penetration depths without the need of disassembling the sample, and they can access the necessary length scales of nanostructures such as DNA. Although X-rays can be used to image living cells, the electron density contrast between the sample and aqueous environment is lower when compared to lyophilized cells. In order to follow the temporal evolution of the DNA compaction throughout the cell division process, we first record time-lapse phase contrast videos of the cells, thus ensuring their previous division history is known. After chemically fixing and lyophilizing the cells, measurements are taken of cells that are at different stages of the division process. The presented data includes analysis on the projected electron density, morphology, compactness, size and aggregation of the nuclear material, and was gathered by combining X-ray nano-diffraction, full-field holography and STED microscopy.