Characterization of the dynamics of amoeboid motility with high spatiotemporal resolution. (A) Traction stresses (force/area) and tension (force/length) for a representative cell at a given instant of time. Color bars at the right side of each traction stress map indicate stress values in [Pa]. (1) Color contours mapping the instantaneous magnitude of the traction stresses, $|τ→|$⁠, in the laboratory reference frame (x_lab, y_lab). The black contour shows the cell outline. The axes (x, y) are aligned with the cell’s principal axes and their origin is located at the cell’s center of mass (x_c, y_c). V indicates the cell’s velocity and the black arrow shows the direction of motion. (2) $|τ→|$ in a reference frame rotated to coincide with (x, y). Green arrows show the intensity and direction of the stresses. (3) Axial traction stresses, τ_x. Stresses pointing toward the cell’s front are considered positive and are shown in red while negative stresses are shown in blue. (4) Integral of τ_x across the width of the cell (axial tension, T_x) as a function of the position along its length. The horizontal axis displays the T_x values in [nN/µm]. Positive and negative values are shown in red and blue, respectively. (5) Lateral traction stresses, τ_y. Stresses pointing toward the right of the cell are considered positive and are shown in red, whereas negative stresses are shown in blue. (6) Integral of τ_y across the width of the cell (lateral tension, T_y) as a function of the position along its length. (B) Spatiotemporal kymograph of T_x(x, t) as a function of the position along the cell trajectory, x, and time, t. At any given instant of time the centroid of the cell is displaced vertically according to its motion so that the cell is moving upward. The inclined red and black lines indicate the instantaneous position of the front and back cell edges. The black contours are cell outlines, shown every 20 s. The color map represents T_x in [pN/µm], plotted every 4 s. Red or blue patches represent positive or negative values of T_x and correspond to tensions aligned with the direction of cell motion or pointing in the opposite direction.