Fig. 1.

Global resection of telomeres detected by PFGE-shift and protection provided by Cdc13 and Yku70. (A) Cells in the CG379 strain background grown to late log at 20 °C (YPDA+SRB) were diluted to fresh medium and shifted to 37 °C. Chromosomal DNA was examined using the PFGE protocols described in the Material and Methods. The PFGE-shift was detected as bands above the main chromosomal bands obtained with cells that were not raised to the higher temperature. (B) Southerns of Chr9 and Chr11 from the gel of 1A probed with respective ³²P labeled probes. The line diagrams correspond to the relative positions of the bands. For example, the lowest band for the double mutant is unresected DNA, the next band up is for molecules with one or the other ends resected, and the upper band corresponds to molecules with both telomeres resected. (C) and (D) comparable experiments except with cells with the W303 background. Note the absence of PFGE-shifted chromosomes in the WT and yku70Δ single mutant.