Fig. 4.

Turnover of Actin and Myosin II Filaments (A) A typical time course of fluorescence images of talin A/B null cells expressing GFP-lifeact after photobleaching. Fluorescence in three regions (anterior, middle, and posterior along the cell) was bleached (a, b, and c). Small “A” and “P” indicate anterior and posterior, respectively. (B-D) Time courses of fluorescence intensities at the bleached regions (a, b, and c). (E) Summary of half times of recovery. Data are presented as mean ± SD and analyzed by one-way ANOVA with Tukey’s multiple comparison test. ** p < 0.0001 (n = 10 for each). (F and G) Typical images of talin A/B null cells expressing GFP-lifeact (F) and GFP-myosin II (G) 15 min after applying 4 µM jasplakinolide. Arrows indicate aggregates at the posterior end. Similar results were obtained in at least 5 independent experiments. (H) Tracking of myosin II filaments after photobleaching the rear region. Upper two panels show confocal and phase-contrast images of a talin A/B null cell expressing GFP-myosin II. Lower panels show a kymograph of a white rectangle in the upper fluorescence image. When myosin II filaments reached around the posterior, they gradually decreased their fluorescence and finally disappeared (arrows). All microscopic images were taken by confocal microscopy. Bars, 10 μm