BPCPPDYSOE21 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 11: Poster A: Single Molecule, Multicellular, Bioimaging, Focus Sessions, etc.
BP 11.16: Poster
Montag, 22. März 2021, 16:30–19:00, BPp
Cytoplasmic streaming enables inter-nuclear signaling in the giant syncytium Physarum polycephalum — •Nico Schramma1, Siyu Chen1,2, and Karen Alim1,2 — 1Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany — 2Technical University of Munich, Physics Department, Munich, Germany
The slime mold Physarum polycephalum is known for its optimized active transport network, which is utilized to spread signals and nutrients over its up to meter-sized cell-body. Intriguingly, this syncytium contains up to billions of nuclei, which are said to divide in a mitotic wave. However, direct experimental evidence of this finding is still missing and the possibility of inter-nuclear signaling remains elusive. Here, by observing fluorescent labeled nuclei with high-speed microscopy, we uncover that individual nuclei not only can be transported in the tubes of the network, but can also get immobilized in the porous, gel-like endoplasm wrapping the tubes. Then, using particle image velocimetry, we resolve the slow flow within the endoplasmic tube-walls. Furthermore, we use a simplified advection-diffusion-reaction model to show that inter-nuclear exchange of large molecules such as mRNA can only happen within physiological time scales between stuck nuclei in the endoplasm, rather than between transported nuclei. Our study provides evidence that immobilised nuclei may play a crucial role in the coordination of mitotic waves or gene-expression patterns in Physarum and may pave the way to use Physarum as a model syncytium to understand the interplay of fluid-driven transport and signaling of nuclei.