Figure 3.

Schematic representation of the experimental design at the level of (a) the device and (b) the microchamber and analysis of the impact of 2-deoxy-d-glucose (2DG) on trypanosome propulsion (c,d). (a,b): The device consists of microchambers along a main channel that connects the cell side with the drug side. Both sides have an inlet and an outlet at the end of the respective Y-split. Panels (I-VI) illustrate individual operational steps in (a) and the resulting relative concentrations of solutions in (b). (I) Channels and microchambers are filled with culture medium, (II) in the absence of applied flow, individual cells are trapped by optical tweezers and moved into a microchamber. (III) Cell movements in a drug-free confinement are recorded while the drug side is flushed with drug-containing solution (Drug) to remove culture medium. (IV) Drug is pumped through the main channel and drug molecules diffuse into the chambers while cell movements are recorded. (V) At maximum drug concentration, the cell side is flushed with culture medium. (VI) Culture medium is pumped from the inlet on the cell-side through the main channel and recording can be stopped. (c) Mean squared displacement (MSD) of trypanosomes in identical chambers but at different concentrations of 2DG in the medium (bright green: drug-free culture medium, dark green: C_2DG = 4 mM, blue: C_2DG = 40 mM, black: C_2DG = 300 mM, magenta: fixed with glutaraldehyde (GA), red: paralyzed; C_2DG = 700 mM). Thin lines are MSD of individual cells; bold lines are averages of a number of cells at the same 2DG concentration. (d) The motility factor $\widetilde{ϵ}$ plotted against the concentration of 2DG in the medium. The dashed black line represents a motility factor $\widetilde{ϵ}$ = 1, which means that the propulsion energy of a trypanosome equals the thermal energy, k_BT. The area shaded in red corresponds to the concentration range of reversible cell paralysis. Dashed blue line serves as a guide to the eye. Adapted from [67].