Figure 6. The AWB sensory neuron mediates PA14 odor preference via neuropeptidergic signaling. A, B, Mutations in genes that encode peptide-processing enzymes, egl-3 and egl-21, disrupt food-odor preference of PA14 to OP50. C–F, Selective knockdown of egl-3 activity in AWB and AWC (C, D, Podr-1::egl-3RNAi) or in AWB alone (E, F, Pstr-1::egl-3RNAi) significantly reduces PA14 preference in wild-type animals. G, H, Deleting the AWB-expressing neuropeptide-encoding gene nlp-9 significantly reduces the olfactory preference of PA14 to OP50. I, J, Selective knockdown of the nlp-9 activity in AWB alone reduces the preference of the PA14 smell to OP50 smell. K, L, Deleting the AWC-expressing neuropeptide-encoding gene nlp-1 significantly reduces the food-odor preference of PA14 to OP50. M, N, Expressing the wild-type nlp-1 activity in AWC olfactory sensory neuron rescues the defect of the olfactory preference of PA14 in comparison with OP50 in nlp-1(ok1470) mutants. O, P, Loss of npr-18 or knocking down npr-18 activity decreases the food-odor preference of PA14 over OP50. Q, Mutations in nlp-9, npr-18, and egl-3 significantly disrupt the aversive response to the repulsive odorant 2-nonanone, a response mediated by AWB sensory neurons. For all, transgenic animals and their nontransgenic siblings, as well as mutants, were compared with the wild-type N2 animals tested in parallel, two-tailed Student's t test. ***p ≤ 0.001, **p ≤ 0.01, *p ≤ 0.05; no asterisk denotes no statistical difference (p > 0.05), n ≤ 3 assays (A–P) or n ≥ 2 separate days (Q), mean ± SEM.