Figure 3. The effect of uric acid on extending life span depends on its activation of transcription factor SKN-1. (A) Life span analysis of the skn-1(zu67) mutant exposed to 2 mM uric acid and that of the untreated control. (B) Life span analysis of wild-type animals exposed to skn-1 RNAi treated with 2 mM uric acid and that of the untreated control. The P value was calculated by the log-rank test, and the life span values of the replicated tests are listed in Supplementary Table 1. (C) skn-1 RNA levels of animals after exposure to skn-1 RNAi E. coli compared with the control (means ± SD, n = 3, ** P < 0.01, Student’s t test). (D, E) Image and quantitation of GFP fluorescence in the transgenic strain CL2166 (gst-4p::GFP) (means ± SD, n ≥ 30, *** P < 0.001, Student’s t test).