Julien Dumont (Institut Jacques Monod). Biophysics seminar ESPCI-ENS

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13 April 13:00 » 14:00 — Conf IV, École Normale Supérieure,

Control of microtubule dynamics in early embryos to adapt spindle size
to cell volume

Successive cell divisions during embryonic cleavage create
increasingly smaller cells, so intracellular structures must adapt
their size to remain functional. Mitotic spindle size correlates with
cell size, but the mechanisms for this scaling remain unclear. Using
live cell imaging, we analyzed spindle scaling during embryo cleavage
in the nematode Caenorhabditis elegans and sea urchin Paracentrotus
lividus. We reveal a conserved scaling mechanism, where the growth
rate of spindle microtubules scales with cell volume, which explains
spindle shortening. Spindle assembly timing is however constant
throughout successive divisions. Analyses in silico suggest that
controlling the microtubule growth rate is sufficient to scale spindle
length and maintain a constant assembly timing. We tested our in
silico predictions to demonstrate that modulating cell volume or
microtubule growth rate in vivo induces a proportional spindle size
change. Our results suggest that scalability of the microtubule growth
rate when cell size varies adapts spindle length to cell volume





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