Fig. 7

Fig. 7 Efficient Front-Rear Coupling and Dynamic Myosin Localization in Migrating Neutrophils In Vivo (A) A 7-min trajectory of a migrating neutrophil in 3-day old zebrafish larvae with 12.5-s intervals. Newly protruded area (green) and newly retracted area (red) were calculated every 12.5 s. Only one third of the time points were colored with green or red for ease of visualization. (B) A 7-min trace of the protrusion speed (green), retraction speed (red) for the cell shown in (A). Total cell area over the same time frame is shown in blue. (C) Cross-correlation between the protrusion speed and the retraction speed for the same cell, showing maximal correlation at zero temporal offset. The magenta shaded region represents a correlation that is below the 95% confidence interval. (D) Maximal intensity projection of inverse fluorescent images of MRLC2-EGFP from migrating cells in (A). The red arrows highlight the spatial discontinuity of each myosin flash. Scale bars in (A) and (D) represent 10 μm. (E) Local edge velocity and local MRLC2-EGFP intensity along the cell boundary. In the edge velocity map, a positive velocity represents local protrusion and a negative velocity represents local retraction, with the unit of μm/min. In the local myosin intensity map, the fluorescence intensity is normalized to the lowest 10% of the cell. (F) Snapshots of MRLC2-EGFP fluorescent images during a flash. All the fluorescent images are inverted. The three time points correspond to the three vertical lines in (E). The number index along the cell contour corresponds to the number along the vertical axis in the heatmaps in (E). Scale bars are 10 μm. (G) Average dynamics of local edge retraction velocity and local myosin concentration. Error bars represent SEM. (H) Distribution of temporal offset between local myosin concentration and local retraction velocity. A positive value means myosin dynamics lags behind retraction velocity.