A Conserved Dopamine-Cholecystokinin Signaling Pathway Shapes Context–Dependent Caenorhabditis elegans Behavior
(A) Frequency of high angled reorientations for wild type and nlp-12(ok335) animals quantified for 5 minutes after transfer to food free plates in the presence (+) or absence (−) of dopamine (DA). Bars represent mean (±SEM) for at least 12 animals. Dopamine mechanosensory signaling is strongly enhanced at low osmotic strength . Therefore, these assays were conducted following transfer of the animals to low osmotic-strength assay plates as described previously . We observed a modest increase in basal reorientation frequency across all genotypes under these conditions. (B, C) Representative images (B) and quantification (C) of NLP-12::VenusYFP fluorescence in the ventral cord region of the DVA process of wild type, dop-1(vs100), and dop-1(vs100) Ex DVA::dop-1 animals before (−) and after (+) 10 minutes dopamine (DA) treatment (wild type: n = 12 for (−) and (+) DA; dop-1(vs100): n = 12 for (−) and 9 for (+) DA). Ex DVA::dop-1 refers to specific rescue of dop-1 expression in DVA using the nlp-12 promoter (−DA, n = 12; +DA, n = 11). Bars represent mean ±SEM. ***, p<0.0005; *, p<0.05 student's t-test. (D) Single slice confocal images of the DVA neuron in a transgenic animal expressing nlp-12::SL2::mCherry (upper panel) together with Pdop-1::GFP (middle panel). White arrow denotes the DVA interneuron in all cases. Asterix denotes a ventral cord motor neuron expressing the dop-1 reporter. Scale bars in B and D, 20 µm. (E) Total directional reorientations measured during 0–5 and 30–35 minute intervals following removal from food for the genotypes as indicated. WT: n = 10; dop-1(vs101): n = 12, dop-1(vs100): n = 14, dop-1(vs100) Ex DVA::dop-1: n = 12 and dop-3(vs106): n = 8. Bars represent mean (±SEM). For (A) and (E) ***, p<0.0005, **, p<0.005 by ANOVA with Sidak's post-hoc test.