Fig. 4.

Further elongation of the long Bcl telomere can occur, and these elongations are made up of Bcl repeats. (A) Southern blot showing an XhoI digest of several long Bcl telomeres that have undergone elongation events. A wild-type control, as described in the legend to Fig. 1, is shown on the left. Black arrows show the positions of elongated telomeres in the sample. (B) Southern blot showing cleavage of DNAs from two subclones that had undergone elongation events with XhoI, XhoI plus BclI, and BsrBI, as indicated. A wild-type control is shown on the left, and “C” represents a control long telomere that has not undergone TRD or elongation. Positions of elongated telomeres in samples 1 and 2 are shown with slanted black arrows, and positions of the elongated telomeres in samples 1 and 2 after cleavage with BsrBI are shown with white arrows. Note that subclones 1 and 2 are not the same subclones as those shown in panel A. Markers for both panels are shown in kilobases.