Fig. 9

Kif23 recruitment to the cleavage furrow is dependent on Ca²⁺ released via IP₃Rs. Panels A and B illustrate FRAP analysis of kif23-EGFP recruitment to the cleavage furrow of embryos at the 16–32 cell stage. Embryos transiently expressing kif23-EGFP (green label) and with microtubules labeled with rhodamine–tubulin (red label) were either untreated (see panels Ai to Av) or treated with a low concentration (i.e., 25 μM) of 2-APB (see panels Bi to Bv) for FRAP analysis. Kif23-EGFP was recruited to the rhodamine–tubulin labeled microtubules during anaphase, at which time photobleaching was performed in the area marked by white squares using a 50 mW argon–ion 488-nm laser source (for 20 consecutive scans with a scan speed of ~ 4 µs/pixel). Images were then captured until interphase to monitor the recovery of kif23-EGFP fluorescence in the photobleached area. (C) Schematic to indicate the orientation of the optical sections shown in panels A and B. (D) Time-course of the recovery of kif23-EGFP fluorescence following photobleaching in the marked region of the representative control and 2-APB-treated embryos shown in panels A and B, respectively. (E) Comparison of the recovery index (RI) of kif23-EGFP fluorescence at the cleavage furrow after photobleaching in control and 2-APB treated embryos. Data presented are averaged percentages of the RI ± S.E.M. where n = 4 or 5 in each group. The Student′s t-test was performed for statistical analysis. * indicates values that are significantly different from the control (at p < 0.001).