Figure 7A-C. Immunofluorescence images of midgut section from the R4 region in 40-day flies (A), 40-day flies with spermidine administration started at 26th day after fly eclosion (B), 40-day flies with spermidine and ALA administration started at 26th day after fly eclosion (C). esg-GFP (green) indicates ISCs and their differentiating cells. Dl (red) staining was used to visualize ISCs. Data information: DAPI stained nuclei are shown in blue. Scale bars represent 10 μm D. Quantification of the number of esg-GFP+ cells, Dl+ cells, pH3+ cells in experiments (A-C). n is indicated. The numbers of quantified guts from left to right are: 15, 18, 17, 15, 18, 17, 15, 18, and 17. 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. E. Quantification of luciferase activity of midguts indicated genotypes and manipulations. Error bars show the SD of six 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. F-I. Representative images of the midgut section from the R4 region of Drosophila carrying esgts-GAL4-driven expression of lacZ cDNA (F, control), Las RNAi (G), Las RNAi and Atg5 cDNA (H), or Las RNAi with spermidine administration (I). GFP (green) and Dl staining (red) was used to visualize ISCs. Data information: DAPI stained nuclei are shown in blue. Scale bars represent 10 μm J. Quantification of the number of esg-GFP+ cells, Dl+ cells, and pH3+ cells in experiments (F-I). n is indicated. The numbers of quantified guts from left to right are 16, 17, 19, 20, 16, 17, 19, 20, 16, 17, 19, and 20. 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. K. Quantification of luciferase activity of midguts with indicated genotypes. Error bars show the SD of six 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. L. 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, 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. M. Quantification of excretion numbers of Drosophila with indicated genotypes. Excretions are quantified in 30 fields for each group of 12 Drosophila. Tests were repeated as 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. N. Survival (percentage) of female Drosophila with indicated genotypes. The numbers of quantified Drosophila: 100 (UAS-lacZ), 100 (Las RNAi), 100 (Las RNAi + UAS-Atg5), and 100 (Las RNAi + UAS-Atg8a). Three independent experiments were conducted. 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. 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. P. Quantification of excretion numbers of Drosophila with indicated genotypes. Excretions are quantified in 30 fields for each group of 12 Drosophila. Tests were repeated as 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.