Fig. 6.

Human Ku86 null cells contain elevated levels of extrachromosomal t-circles. Two-dimensional neutral/neutral gel electrophoresis analyses of AluI-restriction enzyme-digested genomic DNA from the indicated cell lines. After electrophoresis, each gel was transferred to nitrocellulose and hybridized with a ³²P-(C₃TA₂)₃ telomere-specific probe. (A) A diagram showing the expected arced migration of linear genomic DNA (finger) and the elevated arc expected for open-circular (“t-circle”) DNA (arrow). (B–F) Autoradiograms of the gels produced by using AluI-digested genomic DNA from the indicated cell lines: (B) uninfected Ku86^flox/− cells; (C) Ku86^flox/− cells treated with AdCMV; (D) Ku86^flox/+ cells treated with AdCre; (E) Ku86^flox/− cells treated with AdCre; and (F) uninfected ALT WI-38 VA13 cells. (Magnification: 1×.)