Strains carrying deletions in the trp-4 NOMPC channel gene differ in their response to ultrasound stimulation. A, Pressure-response curves of wild-type (blue), VC1141 trp-4(ok1605) (magenta) mutants used in a previous study (Ibsen et al., 2015). Smooth curve fit to the trp-4(ok1605) data yielded Fmax = 65%; P1/2 = 0.83 MPa, slope = 0.13, base = 8%. B, Pressure response curves of three other trp-4 deletion mutants were indistinguishable from wild-type. VC818 trp-4(gk341), TQ296 trp-4(sy695), and GN716 trp-4(ok1605) mutants, which was derived from VC1141 by outcrossing four times with wild-type (N2) animals. C, Response rate in four trp-4 mutant strains. Error bars indicate mean ± SEM reversal rate evoked by ultrasound stimulation with the following parameters: 1 kHz, 50% duty cycle, 200 ms pulse duration, 1.0 MPa. Dotted line indicates the average baseline response rate (see Materials and Methods). The number of animals analyzed across 10 trials is indicated in parentheses. We used PCR to verify that all strains harbored the expected deletions in the trp-4 locus (Materials and Methods). Wild-type data are from Figure 2C.