Fig. 4.
Distribution of deformation, speed, and size across a population of motile vesicles. (A) Distribution of instantaneous deformations. Deformation was measured for each video frame (separated at 5-s intervals) for 121 vesicles. The mean measured deformation for this population was 0.29 ± 0.16. (B) Distribution of speeds. Speed was measured for the interval between each adjacent pair of video images. Most vesicles exhibited large changes in speed over the course of each time-lapse movie. The mean speed was 0.05 ± 0.04 μm/s. (C) Scatterplot of vesicle deformation and size. There is no correlation between the average D for each individual vesicle and its size (R = average unstressed spherical radius in micrometers). (D) Scatterplot of vesicle deformation and speed. There is no correlation between the average D for each individual vesicle and its average speed. (E) Distribution of intratrack cross-correlation coefficients. Crosscorrelation coefficients for deformation and speed (Rds, white bars) and deformation and tail fluorescence (Rdf, gray bars) are symmetric around zero (mean values 0.07 and –0.03, respectively). In contrast, crosscorrelation coefficients for speed and tail fluorescence (Rsf, black bars) are mostly negative (mean = –0.39). See Supporting Text for further details on statistical analysis of individual vesicle behavior.