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Fig. 5. Quantitative analyses of maximum speed (A,D), effective distance traveled during a 98-second period (B,E), and average speed of movements inferred to occur on microtubules based on instant speeds of at least 0.78 µm/second (C,F), obtained by time-lapse fluorescence microscopy analyses of LAMP1-GFP-positive organelles in fibroblasts derived from wild-type (open bars in A-C, open circles in D-F) and pale ear (black bars in A-C, filled circles in D-F) murine strains. Three independent fibroblast lines were analyzed per strain. For each fibroblast line, 10 cells expressing low LAMP1-GFP levels were examined by time-lapse fluorescence microscopy, and the movement of 30 randomly selected, LAMP1-GFP-positive organelles per cell was tracked and analyzed quantitatively. (A-C) Aggregate distributions of values obtained for 900 LAMP1-GFP-positive organelles (30 organelles x 10 cells x 3 fibroblast lines) per strain. Numbers on the x-axis denote bin limits; the last bin on the right includes all values greater than the upper limit of the previous bin, and the first bin on the left of C includes all values smaller than 0.8 µm/second. For comparison, the distributions are also included of maximum speed (A) and effective distance (B) of 120 LAMP1-GFP positive organelles (30 organelles x 4 cells) from wild-type fibroblasts that had been treated with nocodazole to disrupt microtubules (gray bars). (D-F) Median values per cell were plotted as individual data points, where the position on the y-axis represents the median value per cell and the position on the x-axis is arbitrarily chosen to group the data of the 10 cells analyzed for each fibroblast line. Median values obtained for cells expressing the LAMP1-mGFP variant construct and corresponding to two independent fibroblast lines derived from wild-type (open diamonds) and pale ear (filled diamonds) strains are also represented. Horizontal lines represent median values per data group. Statistical analysis of the data represented in D-F was performed using an ANOVA model upon logarithmic transformation, as described under Materials and Methods. The indicated P values correspond to the significance of `genotype' (i.e. pale ear versus wild-type) as an explanatory variable. Exclusion of the data group highlighted by arrows in D and E from the ANOVA analysis did not modify the conclusion that the differences between wild-type and pale ear cells were statistically significant.
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