Formation of telomere fusions after introduction of a linear plasmid.
(A) A Southern blot hybridized with a telomeric probe of
EcoRI-digested DNA isolated from the first streak after
cells were transformed with the K. lactis linear plasmid
pHisLin1. The lower part of the gel is shown more darkly exposed. Both
telomeres of the linear plasmid run at the same position (≈0.5 kb) in
wild-type TER1 cells (lanes 7 and 8). Six independent
small colony transformants of pHisLin1 into ter1-AccSna
are shown in lanes 1–6. Arrow indicates the position of short, unfused
telomeres visible in some of the ter1-AccSna
transformants. (B) Southern blots of
ApaLI + NgoMIV-digested DNA from some of
the same clones after five serial restreaks hybridized with probes
unique to either the left or the right subtelomeric region of the
transformed linear vector. Numbers above lanes match clone designations
from A. Diagram above shows the inferred map of a
typical telomere fusion. White and gray boxes indicate wild-type and
mutant telomeric repeats, respectively. Arrows indicate the direction
of the telomeric ends before fusion. Hatched boxes indicate regions
used as probes and black bar indicates 200 bp. N, E, and A indicate
NgoMIV, EcoRI, and ApaLI
restriction sites.