Figure 1.

Dynamic Reorganization of Cp-Actin Filaments during the Chloroplast Avoidance Response.

(A) Reorganization of cp-actin filaments during the blue light–induced chloroplast avoidance response. Time-lapse images were collected at 31-s intervals for 15 min 56 s. The region in the central portion (5 × 50 µm) indicated by the blue rectangle was irradiated by 458-nm laser scans during the intervals between the image acquisitions. The images are false-colored to indicate GFP (green) and chlorophyll (red) fluorescence. The time points (minutes:seconds) at image acquisition are shown in the top left corner of the pictures. See also Supplemental Movie 1 online for the full time-lapse series. Bar = 10 μm.

(B) The paths of individual chloroplasts. The centers of representative chloroplasts, 1 to 6 in (A), were traced. The image for chlorophyll fluorescence shows the start position before the 458-nm laser scans. Bar = 10 μm.

(C) Kymograph analysis of the asymmetric cp-actin filaments on a moving chloroplast (chloroplast 1 in [A] and [B]). Thirty-one data points obtained from frames 1 (f1) to f31, which corresponded to 00:00 to 15:56 (minutes:seconds), respectively, at the red band (a and b in top panel) were subjected to kymograph analysis (bottom panel). Bar = 5 μm.

(D) Changes in the total cp-actin filament fluorescence at the front (brown line) and rear (blue line) regions of the moving chloroplasts. The intensities of the GFP fluorescence were calculated from kymographs like that shown in (C). The data were obtained from five chloroplasts from three different cells and are presented as mean ± sd. The intensity difference between the front and the rear regions is also shown by the dotted purple line.

(E) Velocity changes during the avoidance movement. The distances between two sequential time-lapse images of the same chloroplasts used for the kymograph analyses in (D) were calculated from the paths. The data are presented as mean ± sd.