Fig. 2: Gustatory responses to acid and other tastants in wild-type (wt), otopla¹ mutant, and rescue (otopla¹; otop-Gal4/UAS-otopla) flies.

a Genomic structures of wild-type and mutant otopla genes. * Represents stop codon. b Feeding responses to neutral foods vs. foods with varying HCl concentrations. Data are presented as mean ± SEM. n = 12 trials, *p = 0.007 (0.001 mM) and *p < 0.0001 (0.01, 0.1, 1, and 10 mM), one-way ANOVA tests. c PER responses to 30 mM sucrose with varying concentrations of HCl. Data are presented as mean ± SEM. n = 12 trials, *p = 0.0039 (0.001 mM) and *p < 0.0001 (0.01, 0.1, and 1 mM), one-way ANOVA tests. d Representative tip recording traces of L6 and S5 sensilla. Arrows indicate the onset of taste stimuli. e, f Dose–response curves showing spikes elicited by different concentrations of HCl in L6 sensilla (e; n = 10 animals, *p < 0.0001 (0.001–100 mM) and *p = 0.0004 (1000 mM), one-way ANOVA tests) and S5 sensilla (f; n = 10 animals). Data are presented as mean ± SEM. g Model of aberrant acid-taste coding in otopla¹. h, i Tip recordings responding to sucrose (50 mM; n = 9 animals), NaCl (50 mM; n = 10 animals), and caffeine (10 mM; n = 10 animals). Arrows in h indicate the onset of taste stimuli. Data in i are presented as mean ± SEM. n.s., not significant, unpaired two-tailed t-tests. j PER assays responding to sucrose (50 mM; n = 10 trials), NaCl (50 mM; n = 10 trials), and caffeine (10 mM; n = 10 trials). Data are presented as mean ± SEM. n.s., not significant, unpaired two-tailed t-tests.