MitOS is required for mitochondrial structure. (A) Wild-type and indicated deletion strains expressing matrix-targeted GFP were grown in SD-dextrose and visualized by fluorescent light microscopy. Representative images of each strain are shown. The graph represents quantification of the mitochondrial morphology in the indicated strains. Data are represented as the mean ± standard error (error bars) of three independent experiments characterizing the mitochondrial morphology of ≥75 cells in each replicate. (B) Wild-type and mutant cells were analyzed by thin-section electron microscopy, and representative images of mitochondria are shown. (C) Representative images of cristae junctions (arrows) observed in wild-type and Δfcj1 cells are shown. (D) Quantification of the widths of cristae junctions observed in electron tomograms of wild-type, Δaim5, and Δaim37 cells. Data are represented as the mean ± standard deviation of three independent measurements. Bars: (A) 2 µm; (B) 200 nm; (C) 20 nm.