Fig. 7

The MOD-1 5-HT-gated chloride channel is the primary mediator of abrupt slowdown upon encountering food. (a) The mean speeds of 5-HT receptor mutants deficient in 5-HT signaling encountering the edge of a bacterial lawn. Wild-type and tph-1 same day controls are shown for comparison. (b) Same as panel (a) for 5-HT receptor mutants that did not negatively affect the abrupt slowdown upon encounter. (c) The number of patches encountered and exploited during 2.5 hours of foraging on a 5 × 5 hexagonal lattice of food patches. Mutants lacking all five serotonin receptors (quintuple) and mod-1; ser-4 double mutants exhibited a strong defect that resembled tph-1 mutants. Single receptor mutants exhibited a mild (mod-1) or no (ser-4) defect. (d) The overall fraction of time spent exploiting food resources in the experiments described in panel (c). Likewise, this criterion suggests that tph-1, the quintuple mutant, and mod-1; ser-4 are mutants similarly deficient, while mod-1 and ser-4 mutants are similar to wild-type. Thick and thin lines or bars and error bars depict mean ± SEM, respectively. In panels (a, b), the number of animals assayed is noted in parentheses for each strain, mean velocities at t = 3–5 sec were compared to wild-type using an ANOVA test corrected post hoc for multiple comparisons using Tukey’s HSD test, and double asterisks denote a significant difference (P <0.01). Pairwise comparisons in panel (c) were performed using t-tests and the means in panel (d) were compared to wild-type using an ANOVA test corrected post hoc for multiple comparisons using Tukey’s HSD test. Single and double asterisks denote significant differences (P <0.05 and P <0.01, respectively). N (wild-type) = 19, N (tph-1) = 9, N (quintuple) = 7, N (mod-1; ser-4) = 8, N (mod-1) = 8, and N (ser-4) = 8