Est1 hybrids do not maintain telomeres ( est1Δ rad52Δ ) or interfere with wild-type Est1 ( rad52Δ ). Telomere DNA Southern blots. Genomic DNA isolated from est1Δ rad52Δ (A) and rad52Δ (B) cells at the indicated passages (P; represented in Figure 2) was digested with XhoI. Strains expressed empty vector (pRS426; vector), wild-type Est1-FLAG, or Est1-FLAG hybrid proteins, as indicated. Telomeres were analyzed by Southern blotting using a (CACACCCA)2CC DNA probe. Lanes 1-18 and 19-28 represent different blots, and data between lanes 25-26 was omitted.