Chromatin alterations at the XIL telomere in core X mutants. (A) Frequency of fluoroorotic acid (FOA) resistance in strains containing the URA3 marker adjacent to the core X element at the XIL telomere. The core Xmut and core Xmut, Δyku80::KanMX strains contain mutations of the ARS consensus sequence (ACS) and Abf1 binding sites at the XIL core X element. The mean and standard deviation of FOA resistance is given for each strain. (B & C) Chromatin structure analysis of the XIL subtelomere in the core Xmut and core Xmut, Δyku80::KanMX strains was performed as described for Figure 1B and 1C. A schematic of the XIL telomere is shown, with black bars indicating the core X ACS and Abf1 binding sites. MNase hypersensitive sites that are altered in the core Xmut strain are indicated by grey arrows.