(A) Schematic of the experiments showing the approximate stage of each
injection.
(B and C) Colchicine injection induced mitotic arrest in control, but not in
Cyclin A+B knockdown, embryos. Mitotic chromosomes were visualized by H2AvD-RFP
(red), and nuclear envelope was visualized by injection of fluorescently labeled
wheat germ agglutinin (WGA) (green). Compare based on indicated timing (min:s)
not alignment.
(D–F) Characterization of Cyclin B3 degradation under different
conditions. Cyclin B3-GFP (green) was stabilized by colchicine in wild-type, but
not in Cyclin A+B-depleted, embryos. APC/C inhibitor UbcH10C114S
blocked this destruction. Mitotic chromosomes were visualized by H2AvD-RFP
(red). Note that in (E) chromosomes exited from mitosis after Cyclin B3-GFP
degradation. Scale bar, 5 mμ.
(G) Quantitation of Cyclin B3-GFP fluorescent intensity after colchicine
injection. Total fluorescence of each frame was measured, normalized, and
plotted against time (minutes into mitosis). Cyclin B3-GFP was similarly
stabilized by injection of recombinant Cyclin B proteins and a known inhibitor
of the APC/C, UbcH10C114S.
See also Figures S1 and
S2 and Movie
S2.