Fig. 4.

Arachidonic acid is involved in autophagy at low temperature. a LC-MS profiling of fatty acids in wild-type (WT) worms at 15, 20, and 25 °C. Relative content of individual fatty acid was expressed as percentage of total measured fatty acid. These results are means ± SD (n = 3). *P < 0.05, 15 °C versus 20 °C. b A mutation in fat-7(wa36) reduced the levels of γ-linolenic acid (GLA, C18:3n6) and arachidonic acid (AA, C20:4n6) in worms at 15 °C. These results are means ± SD (n = 3). **P < 0.01 versus WT. c, d Supplementation with AA (10 µM) significantly restored autophagy in both seam cells (c) and intestinal cells (d) in paqr-2(tm3410), nhr-49(nr2041), and fat-7(wa36) mutants at 15 °C. These results are means ± SD of three independent experiments (n = 30–35 worms per experiment). ***P < 0.001 versus vehicle. Scale bars: 100 μm. P-values (a–d) were calculated using a one-way ANOVA followed by a Student-Newman-Keuls test. e, f Supplementation with AA (10 µM) partially restored lifespan in paqr-2(tm3410) (e) and nhr-49(nr2041) (f) worms at 15 °C. P < 0.05, AA versus vehicle in paqr-2(tm3410) (e) and nhr-49(nr2041) (f) worms. Veh, vehicle. g Supplementation with AA (10 µM) fully rescued lifespan in fat-7(wa36) mutant worms at 15 °C. P < 0.01, AA versus vehicle in fat-7(wa36) worms. See Supplementary Data 1 for details. P-values (e–g) were calculated using log-rank test