Fig. 3.

Chromatid-derived cues are insufficient to induce Myosin relocalization in fly neuroblasts. a Representative image sequence showing a rod mutant neuroblast expressing Sqh::GFP (Myosin, top row; white, bottom row; green) and His2A::mRFP (DNA, bottom row; red) exposed to colcemid. Cortical Myosin intensity was measured at the apical and basal cortex, respectively (dark and light green dashed boxes) and plotted in (b). c Graph showing the mean and standard deviation of basal Myosin clearing in relation to apical depletion (timepoint “0”) for wild-type and rod mutant, colcemid-treated neuroblasts. Kymographs obtained from wild-type (d) and rod mutant neuroblasts exposed to colcemid (e) showing Myosin (green) and DNA (red). The white dashed line indicates the region represented in the kymograph. Kymographs were used to measure the distance between the chromosomes and the apical (yellow arrows) or basal cortex (white arrows). f Scatter plot representing the distance between chromosomes and the basal cortex at the onset of apical Myosin depletion (0 s), at the onset of basal Myosin clearing (60 s) and once basal Myosin depletion is completed (120 s). g Representative rod mutant, colcemid-treated neuroblast expressing Sqh::GFP (white; top panel, green; merge) and His2A::mRFP (red). Myosin and His2A intensity are shown in the 3D graph, corresponding to the ROI represented by the white dashed box. Radar graphs show the distance of the neuroblast’s chromatid to the cortex (h) and Myosin intensity (i) for each of the 16 represented sectors. Yellow sectors represent areas with high DNA-cortex proximity. j Bar graph showing the percentage of rod mutant, colcemid treated neuroblasts displaying cortical Myosin depletion when the proximity of the DNA with the cortex is <2 µm. Center values and error bars represent the mean and standard deviation (s.d), respectively. Asterisks denote statistical significance, derived from unpaired t tests: *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001. Each measured cell (n) is represented with a dot in the scatter plots. For other graphs, the number of measured cells is indicated in the corresponding panels. For each experiment, the data were collected from at least 3 independent experiments. For each independent experiment, at least 5 larvae were dissected. Time: seconds (s). Scale bar: 5 µm. Time scale bars (open white box): 57 s in (d) and 60 s in (e), respectively. n.s. not significant