FIG. 2.

(A) Southern blot analysis of DNA extracted from MK203 at timely intervals. The DNA was digested with ClaI and probed with a fragment of chromosome V carrying the URA3 gene (hatched box) and with LEU2 sequences that served as a loading standard. (B) Quantitative PCR measures the relative amounts of intact chromosome V. Pictured below is a quantitative control reaction with primers complementary to a region on chromosome VIII. (C) Quantitation of Southern blot analysis. “Percent of broken chr. V” refers to the levels of the 2.8 and 1.2 kb fragments resulting from DSB formation. “Ratio of chr. V/chr. III” refers to the ratio between the 4-kb fragment representing unbroken chr. V sequences and the LEU2 band. hs, hour(s).