(A-B) Schematic illustrating behavioral sequence (top) and velocity traces (bottom) from wild type and npr-5 mutants aligned to reversal events, backward locomotion is negative. Dark lines represent mean velocity and shaded region represents standard error. Reversals were spontaneous (A) or induced by a tap stimulus (B). (C) Peak reversal velocity during the first second following the tap stimulus. (D) Mean locomotion velocity during the forward run phase (t = 7-10s). (E) Confocal images of animals expressing an NPR-5::GFP translational fusion protein: zfEx852 [Pnpr-5::NPR-5::GFP]. Upper panel: Z-projection shows strongest expression in head- and neck-muscles and muscle arms. NPR-5::GFP localizes to body-wall and vulval muscle. Body wall muscle arms are visible (arrow heads). Lower left panel: confocal slice showing NPR-5::GFP localization to dense bodies in head muscle. Lower right panel: Z-projection showing high expression in head- and neck- muscle arms and in the muscle plate in the nerve ring (asterisk). Neuronal cell bodies that express NPR-5::GFP are indicated by arrows. Scale bars represent 25 μm. (F-H) Behavioral analysis of NPR-5 overexpression, either from its endogenous promoter (Pnpr-5) or from a muscle specific promoter (Pmyo-3). Mean body curvature averaged over 5 seconds prior to (F), or immediately following (G), a tap stimulus. (H) Quantification of spontaneous reversal frequency. Graphs represent mean ± SEM, significance was calculated using ANOVA with Šidák’s multiple comparison correction (P>0.05 = ns, P<0.005 = **, P<0.0005 = ***, P<0.0001 = ****). Sample sizes: (A-C) (n = # of animals), wild type (n = 512), npr-5 (n = 258). (F-H) (n = # of experiments, 20 animals per experiment). wild type (n = 20), FLP-18(+++) (n = 13), Pnpr-5::NPR-5 (n = 12), Pmyo-3::NPR-5 (n = 14).