Dynamic localization of Endos-RFP and GFP-Tws in syncytial embryos. (A) Time-lapse imaging reveals that GFP-Tws is enriched in the cytoplasm in interphase and becomes enriched in the nuclear/spindle area simultaneously with Endos-RFP in prometaphase until anaphase. (B) The S68A mutation does not alter the localization dynamics of Endos-RFP. For A and B, images from multiple z-steps were combined in an average intensity projection. (C) Time-lapse imaging of an embryo expressing Endos-RFP and injected with 70 kD FITC-dextran to mark the time of NEBD. Endos-RFP is homogenously dispersed throughout the syncytial embryo in interphase until NEBD, when it becomes enriched in the nuclear/spindle area. Images shown are for a single focal plane. (D) The nuclear/cytoplasmic ratios of FITC-dextran and Endos-RFP fluorescence intensities from Video 2 in C were quantified through time relative to anaphase onset. Values are averages of 14 nuclei. Error bars: SD. Scale bars: 5 µm.