PDMs from amino acid ligation of ascr#3-YNE. (a) MS/MS fragmentation of ascr#3-Ser-LNK (19). (b) EICs [M–H]− for ascaroside glycine conjugates 19–22 in acox-1.1, wildtype, and daf-22 exo-metabolomes. (c) Relative abundances for PDMs representing ascr#3-amino acid-LNK conjugates as detected by DIMEN (black) as well as for natural ascr#10-amino acid conjugates in acox-1.1 mutants and wild-type worms (purple and green, respectively), normalized to the abundance of the corresponding glycine conjugate. Absolute abundances of the ascaroside-glycine conjugates are shown in the inset. (d) EICs for ascr#10-Phe (23) in acox-1.1 exo-metabolome, synthetic ascr#10-Phe, and coinjection confirm its identification.