Extended Data Fig. 1: Theoretical XhoI digestion pattern of chromosome ends.

The X, STR, and Y′ elements in each subtelomeric regions are marked with black, grey and white boxes, respectively. The TG1–3 telomeric sequences are marked with arrow tips. The XhoI digestion sites in telomere regions are indicated, and the numbers in kb in parenthesis indicate the sizes of DNA fragments recognized by the TG1–3 probe in the Southern blot analysis.