(A, B) Confocal microscopy of TRN neurons expressing mec-4::mcherry and unc-7a::gfp. (A) Example images of PLM, and composite of the two channels, showing colocalisation in white. (B) Percentage of particles colocalising with particles of the other colour, based on centres of mass coincidence (N = 11, 11, 8, 8; total number of puncta = 161, 141, 156, 92). (C, D) Behavioural response to anterior gentle touch, for genotypes indicated. Animals were stimulated either at the back of the terminal bulb (a3) or approximately 50 µm anterior of the cell body of ALM (a1). Error bars are SE. TRN expression of unc-7 cysless significantly rescued the behavioural defect of mec-4(u253), including when mec-10 was also defective, when stimulated at a3 (p<0.0001 for both); but not when stimulated at a1 (p=0.3423; p=1.0) (N = 40 for each genotype). unc-7(e5) animals are significantly defective in the behavioural response to gentle touch at a3 (p=0.0003) and a1 (p<0.0001), and TRN expression of mec-4 significantly rescued this, at a3 (p=0.0303) and a1 (p=0.0292) (N = 30 for each genotype). (E,F,G) Ca2+ responses to gentle touch recorded in ALM, for wild type, unc-7(e5), and unc-7(e5) animals expressing Pmec-4::mec-4. (E) Average traces of % ratio change. Light gray indicates SEM. (F) Scatter plot showing individual ratio changes (diamonds). Bars indicate mean ± SEM. (G) Graph showing proportion exhibiting a Ca2+ response. Error bars indicate SE. Expression of mec-4 significantly rescued the Ca2+ response defect of unc-7(e5), whether stimulated at a3 (p=0.0064) or a1 (p=0.0033), Fisher’s exact test (N = 21, 17, 13, 32, 16, 16 in the order shown on graphs).