Electric Pulses Can Influence Galvanotaxis of Dictyostelium discoideum

Figure 1

The schematic of the galvanotactic chamber and the electric stimulator, the composition of the electrical waveforms, and the analysis of cell motility in galvanotactic image sequence. (a) The galvanotactic chamber and the stimulator schematics consists of 8 items: (A) the 10-cm Petri dish, (B) the coverslip bridge to observe the cells and let the medium flow, (C) the silicon grease walls to build reservoir, (D) the reservoir to store medium, (E) a pair of agar bridges to connect buffer beakers to the chamber, (F) the buffer beakers to store Steinberg’s solution, (G) Ag/AgCl electrodes to apply electricity, and (H) the stimulator to generate DCEF, pDCEFs, and bpEFs. Inset: top view of the coverslip (B) bridge and agar bridges (E). (b) The variable composition of the electric waveforms: positive stimulation with amplitude of U (A), zero stimulation after positive stimulation (B), negative stimulation with amplitude of -V (C), and zero stimulation after negative stimulation (D). (c) The analysis of cell motility in image sequence: the original position of the cell is P₀ in the first frame, P₁ in the second frame, and the terminal position in the last frame. The EF vector is from anode pointing to the cathode under DCEFs and pDCEFs, or the “net anode” pointing to the “net cathode” under bpEFs. The displacement of the cell is from P₀ to , and its vector is P₀ pointing to . The angle of the cell θ is between the vectors of the EF and its displacement. The trajectory of the cell is algebraic sum of all the displacement between two successive frames.

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