Figure 1.

Competition between human partially deleted mtDNA and primate wild-type mtDNA. (A) Southern analysis of mtDNA in homoplasmic deleted cells. Cell lines homoplasmic for a 7.5-kb deletion were obtained by treating a heteroplasmic transmitochondrial cybrid with ethidium bromide. Shown is a Southern analysis of mtDNA from selected clones after digestion of total DNA with PvuII and probing with an mtDNA rRNA region probe (positions 1462–2463). (B) The cell lines Δ16.10.40 (bottom) and 206ρ° (top) were used as mitochondrial recipients in cybrid fusions with gorilla (left) and human (right) cytoplasts. Fifteen days after fusion, plates were stained with toluidine blue to identify colonies of growing cells. (C) Southern blot analyses of respiration-competent cybrids between Δ16.10.40 and pigmy chimpanzee cytoplasts. DNA from the only two identified clones (ΔHP5 and ΔHP6) and from a control cybrid produced at the same time but with human cytoplasts (ΔHH6) was prepared after 5 wk (left lane) and 10 wk (right lane) after fusion and digested with PvuII before the Southern analyses with a human mtDNA probe (positions 1462–2463). DNA from a normal human cell line (H control), pigmy chimpanzee fibroblasts (PC control), and Δ16.10.40 was analyzed in the same manner.