Mathematical Biology Seminar
Friday, October 18, 2019, 1:30pm, 235 Physics
Stefano Di Talia (Duke University, Cell Biology)
Cell cycle synchronization in early Drosophila embryos

Abstract:

Early embryogenesis of most metazoans is characterized by rapid and synchronous cleavage divisions. While diffusion is too slow for synchronization of mitosis across large spatial scales, traveling waves represent a possible process of synchronization. I will discuss our recent work dissecting the molecular and physical mechanisms for the generation of traveling waves of activity of Cdk1, the master regulator of the cell cycle. I will show that the in vivo dynamics of Cdk1 are captured by a transiently bistable reaction-diffusion model, where time-dependent reaction terms account for the growing level of cyclins and Cdk1 activation across the cell cycle. I will discuss two distinct regimes. The first one is observed in mutants of the mitotic switch. There, waves are triggered by the classical mechanism of a stable state invading a metastable one. Conversely, waves in wild type reflect a transient phase that preserves the Cdk1 spatial gradients while the overall level of Cdk1 activity is swept upward by the time-dependent reaction terms. This unique mechanism generates a wave-like spreading (sweep-waves) that differs from bistable waves for its dependence on dynamic parameters and its faster speed. I will also discuss how the integration of biochemical and mechanical processes is required for the early establishment of synchronization of the cell cycle.

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