Fig. 7.

Rearrangements resulting from a DSB near a telomere in the TERT knockout 10PTKO-A ES cell line. (A) Southern blot analysis of genomic DNA from I-SceI-induced gan^r/puro^r subclones digested with XbaI and hybridized with the pNPTΔ plasmid probe. The limit of resolution (LOR) and position of control bands for endogenous pgk sequences (pgk) are shown. Subclones that were positive (+) or negative (−) by PCR for chromosome healing are indicated. (B, C) Identification of terminal restriction fragments containing telomeres by Southern blot analysis of DNA digested with BAL31 nuclease. Genomic DNA from the A-5, A-23, and A-37 gan^r/puro^r subclones was digested with BAL31 nuclease for 0, 15, 30, 60 and 120 minutes, followed by digestion with XbaI. The DNA was then separated by conventional agarose gel electrophoresis (B), or PFGE (C), and hybridization was performed with the pNPTΔ plasmid probe.