Fig. 2 |. Identification of serotonin-derived MOGLs.

a, Schematic for comparative metabolomics using a low concentration of ¹³C-labeled NAS (5 μM). HPLC traces demonstrate ¹³C-labeling of new serotonin metabolite, sngl#4. b, ¹³C-enrichment of the four most abundant NAS-derived metabolites. c, ESI⁺ MS/MS spectrum and proposed fragmentation of sngl#4. d, Structures of identified serotonin-derived MOGLs and related MOGLs incorporating indole instead of serotonin. e, Synthetic scheme for sngl#1–4 (see Supplementary Information for details) and ESI⁺ ion chromatograms for sngl#3 in C. elegans, synthetic sngl#3 and for coinjection of natural and synthetic sample. f, Concentrations of free serotonin (5-HT), NAS, sngl#1, sngl#2, sngl#3 and sngl#4 in WT C. elegans. Data in b (n = 3) and f (n = 9, except for 5-HT measurement, where n = 12) represent biologically independent experiments, and bars indicate mean ± s.d., P values calculated by unpaired, two-tailed t-test with Welch correction; NS, not significant; rt, room temperature.