Figure 4.

Intermolecular ligation deficiency of rad50Δ cells. (A) mtDNA insertion frequencies after cotransformation of exponentially growing wild-type (PN559), rad50Δ (KT120), and lig4Δ (AD459) cells with PCR-amplified ura4⁺ and mtDNA fragments (1:3 molar ratio). The number of ura4⁺ molecules analyzed is shown in parentheses. Data are the result of at least two independent yeast transformations. (B) Live observation of mitochondria morphology using the atp3-GFP fusion in wild-type cells grown either exponentially or to stationary phase in glucose medium. (C) Insertion frequency of mtDNA fragments in ura4⁺ circles recovered from wild-type and rad50Δ cells grown to either exponential or stationary phase. The number of ura4⁺ circular molecules analyzed is given at the top of each bar. (D) Number of mtDNA pieces ligated to a single ura4⁺ molecule in wild-type and rad50Δ cells grown under both conditions. WT, wild type.