Fig. 4.

Many of the chromosomes in human Ku86 null cells lack telomeres. FISH analyses of metaphase chromosomes with a telomere-specific Cy3-(C₃TA₂)₃ protein–nucleic acid probe. Telomeres are seen as red dots, and metaphase chromosomes are stained blue. (A–D) Four independent metaphases observed in Ku86^flox/− cells treated with AdCre. The percentage of SFEs is shown for each metaphase. (E) An enlargement of 3 chromosomes observed in a metaphase derived from Ku86^flox/− cells treated with AdCre showing the apparent fusion of the sisters either with some residual telomere sequence (small red dots) or apparently lacking all telomeric sequence. Representative metaphases derived from: (F) Ku86^flox/− cells treated with AdCMV, (G) uninfected Ku86^flox/+ cells, or (H) Ku86^flox/+ cells treated with AdCre are also shown. (Magnification: 120×.)