Fig. 6

RNAi knockdown of other ATP synthase subunits in the testis. a-f bam-GAL4-driven UAS-RNAi testis knockdown of ATP synthase subunit paralogs that show either testis-enriched expression (left column) or broad expression across multiple tissues (right column). Two of the three testis-enriched paralogs of peripheral stalk subunits—F6 (a) and g (c), but not b (e)—show a similar knockdown phenotype to knon, with failure of mitochondrial elongation (arrows) in spermatid cysts that have nearly fully elongated, along with individualization failure, a common secondary effect of spermatid morphology defects [6]. Knockdown of broadly-expressed paralogs of subunits F6 (b) and b (f) results in aberrant mitochondrial elongation along with vacuolar inclusions (arrowheads), whereas knockdown of broadly-expressed subunit g (d) results in elongating spermatid cysts of wild-type appearance. g Testis knockdown of the sole ATP synthase α subunit ortholog (bellwether), part of the F₁ portion of ATP synthase, resulted in large vacuolar inclusions and degradation of elongating spermatid cysts. Two representative cysts are shown. Scale bar 20 μm for a-g. For each genotype, >80 spermatid cysts were visualized from >6 dissected males