Telomeric profile of genomic DNA from the ΔTER1 strain transformed with control pHIS3 and pTERBclI plasmids (A,B) or fully functional TER1 deletion mutants (C,D). Each pair of lanes contains DNA digested with EcoRI (R) and EcoRI plus BclI (R/B) enzymes, respectively. Each passage represents ∼25 doublings after the loss of the pTERWT plasmid. The DNAs in C and D were prepared from cells after five passages. The same filters were probed first with the BclI probe (B,D) and subsequently with the wild-type probe (A,C). The asterisk in B is a nonspecific band.