Figure 7. Mitotic waves are kinematic phase waves.

(A) Schematic of the difference between trigger waves and phase waves. Trigger waves involve the transport or diffusion (red line) of material from one neighboring region to another, and depend on positive feedback loops (black circular arrow), which ensure the rapid production of the diffusing species. Phase waves are kinematic phase waves that reflect a delay in timing between neighboring regions (bottom panel). (B) The difference between a trigger wave and a phase wave becomes evident when an impermeable barrier is introduced. A trigger wave is blocked when a barrier is present (top panel), whereas a phase wave is unaffected (bottom panel). (C) Schematic of our prediction that synchronization of mitosis should be disrupted if an impermeable barrier is introduced during S-phase (prior to the S-phase Cdk1 trigger wave) and be unaffected if a barrier is introduced during M-phase. (D-E) Heat-map of Cdk1 activity through time and across the anterior-posterior (AP)-axis of an embryo ligated during S-phase (D) or M-phase (E), respectively. Gray box, ligation barrier; dotted line, prophase wave front; solid line, anaphase wave front. The continuity in (E) of the lines on the two sides of the barrier demonstrates that mitotic waves are indeed phase waves. (F) Anaphase delay (computed as the difference in anaphase time on the two sides of the barrier) caused by the introduction of a barrier in S-phase or M-phase. Error bars, s.e.m. See also Figure S6 and Movies S5 and S6.