(A) Loss of EFHC-1 or TRP-4 impairs activation of CEP neurons upon gentle mechanical stimulation (buzz), resulting in fewer animals responding to the stimulus compared to wild-type animals. In contrast, efhc-1 or trp-4 mutants can respond to stronger stimulation (press). In this panel, n represents the total number of animals assessed. Each bar represents the number of worms responding to mechanical stimulation over the total number of worms assessed per strain, and the error bars represent the binomial confidence intervals. Binomial logistic regression followed by Tukey’s HSD (honest significant difference) test was used to determine significance for each pair of strains. Differences between all strains subjected to the press stimulus are not significant, but differences between wild-type and efhc-1 (p < 0.01) or trp-4 (p < 0.05) mutants subjected to the buzz stimulus are significant. (B) The peak ratio change (%), representing the amplitude of the neuronal response, is similar between strains for animals responding to each stimulus. In this panel, n represents the number of animals responding to the stimulus over the total number of animals assessed. (C) The axonemal structure of CEP neurons by TEM cross-section (refer to schematic) is not abrogated in efhc-1 mutants. Scale bars, 100 nm. (D) The localization of the mechanosensory channel, TRP-4, which is comparable to that of EFHC-1, is unaffected in efhc-1 mutants. Lengths of CEP and OLQ cilia measured in trp-4 and trp-4;efhc-1 mutants are indistinguishable. Each dot represents one cilium. Kruskal-Wallis rank sum test (CEP cilia lengths) and Tukey's Honest Significant Differences (OLQ cilia lengths) were used for calculating the statistical significance. ns, not significant. Scale bar, 3 μm. For complete statistical comparisons (p values) see Supplementary file 2.