Figure 2.

Telomere shortening caused by Trt1p mutations. (A) Diagram of hybridization with telomeric probe. In wild-type S. pombe telomeres, EcoRI cuts ≈1 kb from the telomere end. With shortening telomeres, shorter EcoRI-fragments and weaker hybridization signals are expected up to the point at which the whole telomeric repeat sequence is lost. (B) Telomere blot of EcoRI-cut DNA from S. pombe strains CF199 (wild-type), CF797 (starting strain for plasmid shuffle), and frozen cultures of days 1, 3, and 5 from growth curves of strains carrying pKAN1-trt1⁺ (wt) or pKAN1-trt1^mut. To test for equal loading, the blot was also hybridized with a probe to the single-copy gene encoding DNA polymerase α (pol1⁺), which lies on a 5.6-kb EcoRI-fragment.