FIGURE 3:

Forced activation of the CPC induces ectopic furrows. Monospermic eggs were injected after first mitosis (60–70 min postfertilization) and time-lapse imaged to score cleavage (A, C, E), or fixed around the time of first cleavage and stained for tubulin and AurkB for CPC (B, D, F). (A, B) Injection with an activating anti-INCENP IgG. (A) Note multiple ectopic furrows. (B) Note ectopic microtubule assemblies with CPC strongly localized to their peripheries. Furrows initiated where CPC planes touched the cortex (white arrows). (C, D) Injection with inhibitory IgG to MCAK (Kif2C), the predominant microtubule catastrophe factor in frog eggs. (C) Note multiple ectopic furrows. (D) Note ectopic, CPC-positive microtubule assemblies and associated ectopic furrows (white arrows) as in B. (E, F) Injection with buffer only. A single cleavage furrow forms (E and white arrow in F).