Figure 10. w1118/OreR heterozygous males carrying COII^G177S mutant mtDNA show rescued sperm development and COX activity.

Representative DAPI stained images of the late needle stage of sperm development from w1118/w1118 males carrying either wildtype mtDNA (A), or COII^G177S mtDNA (B) compared to heterozygous w1118/OreR males carrying COII^G177S mtDNA (C). Numbers of examined males with defects in sperm development are indicated. Arrow points to ‘clumped’ sperm. Note the presence of many individualized sperm (arrowheads) in A and C but few in B. Scale bar, 20 μm. We stained sperm from homozygous w1118/w1118 males (D) and w1118/OreR heterozygous males (E), both carrying COII^G177S mutant mtDNA with mitotracker Green (green) and mitotracker CMS Rox (magenta), which stain immotile and motile sperm respectively. All flies were raised at 29°C. Scale bar, 20 μm. (F) COX activity measured from young (3–4 day old) w1118/w1118 males and w1118/OreR heterozygous males both carrying COII^G177S mutant mtDNA. All flies were raised at 29°C. Data is normalized to flies with wildtype mtDNA in the corresponding nuclear background. Error bars represent standard error of the mean.

DOI: http://dx.doi.org/10.7554/eLife.16923.023

Figure 10—figure supplement 1. Seminal vesicle size is restored in aged 'suppressor' backgrounds in males containing COII^G177S mutant mtDNA raised at 25°C.

(A) Representative DAPI stained images of seminal vesicles (outlined in dotted line) from either w1118/w1118 or w1118/OregonR males containing either wildtype mtDNA or COII^G177S mutant mtDNA. All males were raised at 25°C and allowed to age before dissection. Note the much smaller seminal vesicle sizes in COII^G177S mutant mtDNA containing aged w1118/w1118 males are completely restored in the w1118/OregonR males. Scale bar, 100 μm. (B) Quantification of the seminal vesicle size, as measured by cross-sectional area, normalized to aged wildtype mtDNA males raised at 25°C (data from Figure 7—figure supplement 1 is reproduced here for easy comparison). Average calculated from 5–7 testes. Error bars represent standard error of the mean.

DOI: http://dx.doi.org/10.7554/eLife.16923.024

Figure 10—figure supplement 2. COX activity is specifically restored in ‘suppressor’ nuclear backgrounds.

We measured COX activity from young (3–4 day old) w1118/w1118 males carrying COII^G177S mutant mtDNA; the latter showed a 20% reduction in COX activity. We also measured COX activity in three heterozygous nuclear backgrounds (similar to Figure 10F) and found there was no reduction in COX activity in flies carrying COII^G177S mutant mtDNA. Instead, in one instance, in w1118/Congo26 males, we observed a significant enhancement of COX activity associated with the COII^G177S mutant mtDNA. All flies were raised at 29°C. Data is normalized to flies with wildtype mtDNA in the w1118/w1118 nuclear background.

DOI: http://dx.doi.org/10.7554/eLife.16923.025