Figure 7: Maintenance of the central position of the metaphase plate is actin and microtubule independent.

(a) Control embryo expressing His–RFP (purple or black, Z-projection over 20 μm). One picture is shown every 15 min. Scale bar, 10 μm). (b) Left panel: Control embryo expressing His–RFP (purple, Z-projection over 20 μm) after chromosome merging. Scale bar, 10 μm. Right panel: graph showing the position of the centroid of the chromosomes in the referential of the embryo (0 being the centre) from metaphase to anaphase for representative control embryos. The scale is represented by the white box on the left panel. Each colour represents an embryo. The arrows point to the last position recorded before anaphase. One time point is shown every 15 or 20 min. (c) Left panel: control metaphase embryo (upper panel) and embryo treated with 1 μg ml⁻¹ Cytochalasin D (CCD) in metaphase (lower panel) expressing GFP–UtrCH (black, one Z-plane is shown) and His–RFP (purple, Z-projection over 20 μm). Scale bar, 10 μm. Right panel: Same as b for embryos treated with CCD in metaphase. (d) Bar graph showing the chromosome mass distance to the embryo centre in metaphase for controls (black bar) and embryos treated with CCD in metaphase (orange bar). Mean is shown of 23 controls and 18 CCD-treated embryos from 2 independent experiments. s.e.m. is plotted on each bar. Statistical significance of differences is assessed with a Mann–Whitney test (P value 0.204). (e) Left panel: control metaphase embryo (upper panel, same as in Fig. 4a) and embryo treated with 1 μM Nocodazole in metaphase (lower panel) expressing EB3–GFP (green, one Z-plane is shown) and His–RFP (purple, Z-projection over 20 μm). Scale bar, 10 μm. Right panel: Same as b for embryos treated with 1 μM Nocodazole in metaphase. (f) Bar graph showing the chromosome mass distance to the embryo centre in metaphase for controls (black bar) and embryos treated with Nocodazole in metaphase (green bar). Mean is shown of 23 controls and 12 Nocodazole-treated embryos from 2 independent experiments. s.e.m. is plotted on each bar. Statistical significance of differences is assessed with a Mann–Whitney test (P value 0.2203).