Figure 3. The pharyngeal nervous system does not influence EPG parameters during optogenetically paced pumping.

(a) Pump duration during 1 Hz pacing compared in wild type (wt) and unc-13(s69) mutant (n = 7 pharynxes). (b) Schematic depicting transgenic pharynxes used in experiments in (c,d). The pharynx expresses ChR2 in PMCs and cholinergic pharyngeal neurons express halorhodopsin (NpHR). While ChR2 is activated by 470 nm light pulses (blue tick marks) to induce pumping, cholinergic neurons are hyperpolarized by continuous illumination (1 min) with 590 nm light (yellow bar) (c) Spontaneous pump rate in presence of bacteria, in pharynxes as described in B, from animals raised in the absence or presence of ATR, as indicated. Yellow-light induced hyperpolarization of cholinergic neurons affects spontaneous pump rate (t-test with Bonferroni correction, ***P < 0.001). (d) Mean pump rate, visually counted for 30 s during 4 Hz optical pacing (35 ms, 470 nm) is not impaired by hyperpolarization of cholinergic neurons using yellow light (middle). Compared is frequency before (left) or after yellow light (right).