Two parallel β-oxidation pathways shorten the side chains of the (ω-1)-ascarosides (a) and the ω-ascarosides (b). Each cycle shortens the side chains of the ascarosides by two carbons. The boxed structures are four of the five dauer pheromone components shown in Figure 1a. Figure is adapted.61 Note that in order to reflect their similarity to mammalian ACOX-1, C. elegans ACOX-1, -2, -3, -4, -5, and F59F4.1 have been officially renamed ACOX-1.1, -1.2, -1.3, -1.4, -1.5, and -1.6, respectively. To reflect its similarity to mammalian ACOX-3, C. elegans ACOX-6 has been renamed ACOX-3. There are no C. elegans homologs of mammalian ACOX-2.