O. Quantification of three categories of midguts treated with the pH indicator Bromophenol Blue in Drosophila with indicated genotypes. The numbers of quantified guts from left to right are 90, 90, 90, and 90. Error bars show the SD of three independent experiments. Data information: Error bars represent SDs. p-values for lifespan curves (N) were calculated by the log-rank test. The statistical tests used in other panels were student's t-tests. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, and non-significant (NS) represents p > 0.05. 