Fig. 4: The lack of Aub induces a switch in energy metabolism in GSCs.

a–b’ Transmission Electron Microscopy images of a wt (a) and an aub^QC42/HN2 mutant (b) GSC. The white arrow in wt and yellow arrow in aub mutant GSCs point to mitochondria that are shown enlarged in (a’) and (b’). c Measurement of mitochondrial length in wt and aub^QC42/HN2 mutant GSCs from the Transmission Electron micrographs. Percentages of mitochondria with a length above or below 0.25 μm are shown. The number of mitochondria (n) from at least ten GSCs per condition is indicated. *p-value <0.05 using the χ² test. p = 0.025. d Quantification of mitochondria with and without cristae in wt and aub^QC42/HN2 mutant GSCs from the Transmission Electron micrographs. Percentages of mitochondria with and without cristae are shown. The number of mitochondria (n) from at least ten GSCs per condition is indicated. ****p-value <0.0001 using the χ² test. p = 1.0e−5. e, e’ Confocal images of a mosaic germarium containing an aub^HN2 mutant clonal GSC stained with anti-GFP (green), anti-ATPsynα (red) and DAPI (blue). The non-clonal (GFP⁺) and aub mutant clonal (GFP^-) GSCs are indicated by dashed white and yellow lines, respectively. f Quantification of ATPsynα protein levels in control non-clonal aub^HN2/+ and clonal aub^HN2 mutant GSCs using fluorescence intensity measured in arbitrary units using the ImageJ software. Horizontal bars represent the mean and standard deviations. *p-value < 0.05 using the paired two-tailed Student’s t test. p = 0.026. g, h Quantification of mitochondrial membrane potential: ratiometric images of wt and aub^QC42/HN2 mutant germaria stained with TMRM to record mitochondrial membrane potential and Deep Red MitoTracker to record mitochondrial mass. The ratio of TMRM to MitoTracker intensity was calculated using ImageJ and a pseudo-colored image was generated using the rainbow RGB gradient. White and yellow arrows indicate wt and aub mutant GSCs, respectively. i Quantification of TMRM/MitoTracker ratios in wt and aub^QC42/HN2 mutant GSCs using ImageJ. Horizontal bars represent the mean and standard deviations. **p-value < 0.01 using the two-tailed Mann–Whitney test. p = 0.0019. Scale bars: 1 μm in (a, b); 10 μm in (e, g, h). Source data are provided as a Source Data file. Panel (a’) and (b’) were created with BioRender.com released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license (https://creativecommons.org/licenses/by-nc-nd/4.0/deed.en).