Figure 4.

FZO1 is required for mitochondrial fusion during mating. fzo1-1 cells of opposite mating type (JSY2802 and JSY2804) were labeled with mito-GFP or Mitotracker red and mated at 25° (A–D) and 37°C (E–H and I–L). Confocal microscopy was used to score the distribution of mito-GFP (green in B, F, and J) and Mitotracker (red in C, G, and K) in serial optical sections (representative single optical section are shown). Fusion and mixing of mitochondrial contents (yellow in D) was evaluated in merged mito-GFP and Mitotracker red images (D, H, and L). Zygote morphology was visualized by phase-contrast microscopy (A, E, and I). The zygote bud is on the right in A and on the top in I. White arrows, regions where parental mitochondrial membranes have intermixed. Bar, 5 μm.