Figure 4. The effect of uric acid on extending life span depends on its regulation of the IIS signaling pathway. Survival analysis of (A) daf-16 (mu86), (B) daf-2 (e1370), (C) hsf-1 (sy441) mutant worms treated with 2 mM uric acid and of the untreated control (P value by log-rank test). The life span values of the repeat experiments are summarized in Supplementary Table 1. (D) QPCR analysis of the mRNA level of target genes daf-16 and hsf-1 when animals were exposed to 2 mM uric acid versus the control (means ± SD, n = 3, * P < 0.05, ** P < 0.01, Student’s t test). (E, F) Images and quantification of GFP fluorescence of transgenic strain CL2070 (hsp-16.2p::GFP). Data are the means ± SD, n ≥ 30, ** p < 0.01 (Student’s t test).