mtDNA replication is indispensable for selective inheritance. (A and B) mtDNA replication labeled by EdU staining in germarium. The Hts-1B1 antibody was used to stain the fusome, which indicates the developmental stages of germ cells. Region 2B is outlined in white and enlarged (right panels). Note that the mtDNA replication was specifically disrupted at region 2B in mt:CoI^T300I ovary at 29°C but was restored by overexpression of AOX driven by nanos-gal4 (A). Knocking down mtSSB using nanos-gal4 diminished mtDNA replication at region 2B, but not in egg chambers (B). Arrows point to EdU puncta. Scale bars, 10 µm; enlarged images, 5 µm. (C) Quantification of mtDNA replication indicated by numbers of EdU puncta in regions 1 and 2B in genetic backgrounds shown in A and B (1, n = 11; 2, n = 18; 3, n = 17; 4, n = 20). Data presented are means ± SD. ***, P < 0.001. (D and E) Selection against ts mtDNA at 29°C was compromised by ectopic expression of AOX (D) and knockdown of mtSSB (E; n = 10 for each genotype). Both lines were driven by nanos-gal4. Data presented are means ± SD. P < 0.001.