3D shape changes and traction stresses of a chemotaxing D. discoideum wild-type cell expressing lifeact-GFP. Cells were transformed to generate lines expressing Lifeact (Abp140-GFP) to define the cell’s 3D shape. Z stacks of each time-lapse sequence of the chemotaxing cell were acquired every 12 s on a spinning disk confocal microscope (DMIRE2 [Leica]; CSU10 [Yokogawa]) controlled by Slidebook software (3I). Calculation of the traction stresses was performed using MATLAB and an inverted light microscope (TE300; Nikon) controlled by MetaMorph software (Molecular Devices). The 3D cell shape is shown in gray and the rendering of the shape as well as the generation of this video were performed using the IMARIS software (Bitplane). The movie corresponds to Fig. S1 (E and F) and is accelerated 60× real time.
