Spindle Heterogeneity, Microtubule Search and Capture, and Bulk Actin Waves
Mechanically Distinct Microtubule Arrays Determine the Length and Force Response of the Meiotic Spindle
Takagi et al. | Developmental Cell
The spindle is a remarkable macromolecular machine comprised of dynamic microtubules and associated factors. Given its critical job in driving chromosome segregation, the spindle is robust to mechanical perturbations, maintaining a near constant structure despite a barrage of internal and external forces. Previous works have delved into the architecture and dynamics that give rise to the steady-state spindle, but a map of how microtubules in various regions of the spindle respond to forces is needed. In this study, the Shimamoto lab locally deformed spindles in Xenopus egg extracts with force-calibrated microneedles while simultaneously imaging single microtubules labeled with fluorescent tubulin speckles. The mechanical responses of microtubules were observed to differ depending on their location within the spindle, with the middle of each spindle half being more compliant and fluid-like than than pole and equatorial regions. This mechanical heterogeneity was further demonstrated to emerge from the microtubule crosslinking activities of kinesin-5 and dynein, providing a link between spindle architecture and mechanics.
Discussion Point – The authors propose that the compliant region located in the middle of each spindle half acts as a buffer zone – allowing the spindle to make necessary adjustments in response to physical perturbations without disrupting activity at the pole and equatorial business ends.
Preview by Juraj Simunić and Iva Tolić
Designing A Rigorous Microscopy Experiment: Validating Methods And Avoiding Bias
Important considerations for one of the mostly widely used techniques in cell biology – from sample preparation to post-acquisition processing.
Jost and Waters | Journal of Cell Biology
Reviews and Perspectives
Microtubule Assembly From Single Flared Protofilaments – Forget The Cozy Corner?
Cooperative assembly of FtsZ, the bacterial tubulin homolog, may help explain new models of microtubule assembly characterized by the elongation of single protofilaments.
Erickson | Biophysical Journal
French Microtubule Network 2019
July 1-2, 2019
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Journal Club Picks
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