Figure 2.

Kinematics of freely swimming cells. (a) Overlaid image sequence from a typical observation. The time interval between the overlaid snapshots is 200 ms. The red line represents the position of the center of the tracked cell. The white arrows depict the heading angle θ of the cell. The inset shows the instantaneous velocity for the cell in the image with the maximum velocities highlighted by the triangles. (b–d) Comparison of (b) mean swimming speed, (c) beating frequency $f_0$, and (d) maximum swimming speed $U_{max}$ for mstg, cw15, and cc125 cells from left to right, respectively. (d) $U_{max}$ represents the median of the peak velocities depicted in the inset of (a) and is normalized by $U_0=L{f}_0$, where L is flagella length. In (c), ^∗∗ represents $p<0.01$ and ^∗∗∗ represents $p<0.001$. The distributions in (b–d) are compared using the Kruskal-Wallis one-way ANOVA statistical test. For (b–d), and all distributions in the subsequent figures, the red lines represent the medians and the bottom and top of the boxes the 25th and 75th interquartiles, respectively. The whiskers represent data between $q_1-1.5\left(q_3-q_1\right)$ to $q_3+1.5\left(q_3-q_1\right)$, where $q_1$ and $q_3$ are the 25th and 75th interquartiles, respectively. Any points outside of this range are marked as red crosses and considered outliers. To see this figure in color, go online.