Figure 8

Localizations of myosin and Dynacortin in chemotaxing cells. Fluorescent images of a chemotaxing Dictyostelium cell expressing mCherry-dynacortin and GFP-myosin-II. A chemoattractant gradient was created using a micropipette needle on the left as previously described [34]. Small arrows placed near cell membrane point to the pseudopodial activities. The numbers at the right upper corners represent the time (in seconds) from the beginning of the movie. The scale bar represents 5 μm. B, D. Fluorescent intensity of mCherry-dynacortin (B) or GFP-myosin-II (D) as a function of time around the cell perimeter for the cell in panel A. The data is normalized between minimum (0) and maximum (1). C. Pseudopod activity as a function of time for the cell in panel A using the same color scheme as in Figure 5D-F. E. Cross-correlations between the two fluorescently-tagged proteins and protrusion or retraction activities as a function of time and angle. Left panels: averaged over 37 cells; right panels: averaged over 100 cells. F. Changes of local protrusion or retraction length in one frame as a function of the local intensity of GFP-myosin-II (100 cells, 4254 frames) or mCherry-dynacortin (37 cells, 1533 frames). Error bars represent standard errors.