Supplemental Materials
This article contains the following supporting material:
- Supplemental Materials
- Movie 5 - Video 5. DIC time-lapse movie of wild-type Dictyostelium cells moving on a collagen I-coated polyacrylamide substratum. Cells were pulsed for 8 h and time-lapse DIC sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Playback rate is 40× real time (10 frames/s) and scale bar is 10 μm long (corresponds to Figure 7).
- Movie 9 - Video 9. DIC time-lapse movie of tgrB1- cells moving on a collagen-coated polyacrylamide substratum. Cells were pulsed for 8 h and time-lapse DIC sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Playback rate is 40× real time (10 frames/s) and scale bar is 10 μm long (corresponds to Figure 7).
- Movie 7 - Video 7. DIC time-lapse movie and traction stresses exerted by a tandem wild-type Dictyostelium pair moving on a DiscI-coated polyacrylamide substratum. The contour of the pair is shown in black. The magnitude of the traction stresses that the pair exerts is indicated with the colormap shown on the upper right part of the movie Pa. The scale bar is 10 μm long. Time-lapse sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Calculation of the traction stresses and generation of the video images were performed using MATLAB (Mathworks Inc, Natick, MA). Playback rate is 40× real time (10 frames/s) (corresponds to Figure 7).
- Movie 1 - Video 1. DIC time-lapse movie and traction stresses exerted by a tandem wild-type Dictyostelium pair moving on a collagen-coated polyacrylamide substratum. The contour of the pair is shown in black. The magnitude of the traction stresses that the pair exerts is indicated with the blue colormap shown on the upper right part of the movie Pa. The scale bar is 10 μ m long. Time-lapse sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Calculation of the traction stresses and generation of the video images were performed using MATLAB (Mathworks Inc, Natick, MA). The video refers to the tandem pair shown in Figure 2 but includes additional time points. Playback rate is 40× real time (10 frames/s) (corresponds to Figure 1).
- Movie 8 - Video 8. DIC time-lapse movie and traction stresses exerted by a tandem wild-type Dictyostelium pair performing a turn while moving on a collagen-coated polyacrylamide substratum. The contour of the pair is shown in black. The magnitude of the traction stresses that the pair exerts is indicated with the colormap shown on the upper right part of the movie Pa. The scale bar is 10 μm long. Time-lapse sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Calculation of the traction stresses and generation of the video images were performed using MATLAB (Mathworks Inc, Natick, MA). Playback rate is 40× real time (10 frames/s) (corresponds to Figure 7).
- Movie 3 - Video 3. 3D shape changes, F-actin localization and traction stresses of a tandem wild-type pair implementing only Mode 1. Cells were transformed to generate lines expressing Lifeact (Abp140-GFP) to define the pair' s 3D shape. Z-stacks of each time-lapse sequence of the pair were acquired every 12 s on a spinning disk confocal microscope (Leica DMIRE2, Yokogawa CSU10) controlled by Slidebook software (3I, Denver). Calculation of the traction stresses was performed using MATLAB. The 3D pair's shape is shown in gray and the rendering of the shape as well as the generation of this video was performed using the IMARIS software (Bitplane, Z?rich, Switzerland)). The panel on the left side shows the 3D pair shape together with the traction stresses it exerts on its substratum. The panel on the right side shows the 3D pair' s shape together with the localization of F-actin. The pair moves from left to right. Note that the pair always actively adheres at 4 TAs, suggesting that it only implements Mode 1, moving as two contractile dipoles. The movie corresponds to Figure 3 and is accelerated 24× real time (corresponds to Figure 3).
- Movie 10 - Video 10. DIC time-lapse movie of tgrC1- cells moving on a collagen-coated polyacrylamide substratum. Cells were pulsed for 8 h and time-lapse DIC sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Playback rate is 40× real time (10 frames/s) and scale bar is 10 μμm long (corresponds to Figure 7).
- Movie 2 - Video 2. Time evolution of the axial traction stresses and corresponding progressive emergence of the axial tension kymograph for a streaming tandem wild-type Dictyostelium pair. The tension kymograph of a representative tandem pair, shown on the left, is progressively built by adding the traction tension Tx at each instant of time while the instantaneous pair contour (black) moves upward with the pair' s centroid velocity V. Red and black lines indicate the position of the front and back pair edge. Motility has been split into cycles comprised by four phases, based on the quasi-periodic oscillations of the total strain energy of the pair and by using phase statistics. All individual time points have been assigned to the four phases and are shown as colored dots superimposed on the red line showing the front cell edge (blue, protrusion; red, contraction; green, retraction; black, relaxation). The insert in the upper left corner shows the oscillations of the strain energy, Ux(t) (blue line) and the current value of Us(t) (red circle). The graph on the right shows the instantaneous axial traction stresses together with the instantaneous outline of the pair (black contour). Time-lapse sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Calculation of the traction stresses and tension and generation of the video images were performed using MATLAB (Mathworks Inc, Natick, MA). The video refers to the tandem cell pair shown in Figure 2 but includes additional time points. Playback rate is 40× real time (10 frames/s) (corresponds to Figure 2).
- Movie 6 - Video 6. DIC time-lapse movie of wild-type Dictyostelium cells moving on a DiscI-coated polyacrylamide substratum. Cells were pulsed for 8 h and time-lapse DIC sequences were acquired every 4 s on a Nikon TE300 inverted light microscope controlled by the MetaMorph software (Molecular Devices, Sunnyvale, CA). Playback rate is 40× real time (10 frames/s) and scale bar is 10 μm long (corresponds to Figure 7).
- Movie 4 - Video 4. 3D shape changes, F-actin localization and traction stresses of a tandem wild-type Dictyostelium pair implementing Modes 1 and 2. Same as Video 3 but for a tandem pair implementing Mode 2 (3 TAs, frames 1-5) and then Mode 1 (4 TAs, frames 6-19) and moving from left to right. The movie corresponds to Figure 3 and is accelerated 24× real time (corresponds to Figure 3).