a, Representative expression of Lysosensor, Lysotracker, Lamp1-mCherry and hodor-Gal4-driven p62-GFP in the copper cell region of control larvae, larvae in which the V-ATPase subunit Vha44 has been downregulated in interstitial cells (using hodor-Gal4) or hodor mutant larvae. Vha44 knockdown and, to a lesser extent, hodor mutation result in an increase in the number of punctae positive for these markers. b, Quantifications of the number of punctae positive for the above mentioned markers in all three types of larvae shown in a. c, hodor mutants expressing the dual autophagosome/autolysosome marker UAS-GFP-mCherry-Atg8a in all enterocytes (using mex1-Gal4) show regional enrichment of autophagy in both the copper cell (#) and iron cell (*) regions when compared to an anterior portion of the gut (^). Note the appearance of GFP-positive punctae in the copper cell region (#), suggestive of defective autolysosomes unable to quench the GFP signal. d, hodor-Gal4-driven expression of GFP-mCherry-Atg8a in interstitial cells of starved hodor mutants. Large subcellular compartments positive for both GFP and mCherry are apparent. e, Quantification of GFP- and/or mCherry-positive Atg8a-expressing autophagosomes/autolysosomes in the copper cell region of fed or starved controls, and fed or starved hodor mutants (left graph, Atg8a reporter expressed from hodor-Gal4; right graph, Atg8a reporter expressed from mex1-Gal4 in fed hodor mutants). See Supplementary information for sample sizes and full genotypes. Scale bars: a, 30μm; c, 500μm; d, 45μm. Where more than two groups were compared, an ordinary one-way ANOVA test was performed with a Tukey post-hoc test. Significance values are denoted as follows: p< 0.05 *, p< 0.01 **, p< 0.001 ***. Box plots: line, median; box, 75th–25th percentiles; whiskers, minimum to maximum.