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Figure 9
(A) Lateral images from the ventral spinal cord of living larvae labeled with sox10:eGFP-CAAX (in green) and one of the following: myrf:tagRFP, myrf:tagRFP-RAB5C, myrf:tagRFP-rab5CS36N (all in magenta); and time-lapsed for 15 hours from 2.5-3dpf. The first panel is an image taken immediately before starting the time-lapse experiment. The subsequent panels are the same cells at the peak of sheath accumulation, at 3dpf, and at 4dpf. The images and data for the control are the same as for the ventral group in Figure 6. (Scale bar = 5 μm). (B) Total ensheathment attempts per cell. (C) Peak sheath number per cell. (D) Sheath number at 3dpf per cell. (E) Final sheath number per cell at 4dpf. (F) Net sheaths lost from the peak to 4dpf. (G) Percent of sheaths stabilized during the accumulation phase (peak sheath number/total ensheathment attempts). (H) Percent of sheaths stabilized during the stabilization phase (final sheath number/peak sheath number). (I) Percent of total sheaths stabilized across both the accumulation and stabilization phases (final sheath number/total ensheathment attempts). (J) Simple linear regression comparing the total number of ensheathment attempts to the final sheath number at 4dpf for each cell. (control n=18 cells/18 larvae, wild-type Rab5 n=18 cells/18 larvae, Rab5DN n=18 cells/17 larvae). The dashed lines in each plot represent average values with all data points shown. The error bars are standard deviation. Significance was determined using global Kruskal-Wallis tests. These p-values are shown for B-D and G since they were not significant. Post hoc multiple comparisons tests were not performed for these analyses. Post hoc Dunn’s multiple comparisons tests were done for E, F, H, and I and the individual p-values are shown. (J’) The slopes of the Rab5WT and Rab5DN regression lines from J were compared to the control in Graphpad by (two-tailed) testing the null hypothesis that the slopes are identical (the lines are parallel). P-values are shown in the table. (See associated source data and supplementary video files).
Over-expression of the Rab5 dominant-negative mutant in oligodendrocytes reduced sheath stability in the stabilization phase.