FIG 5.

Telomerase-null cells form stable telomeres without elongation after induction of chromosome breakage. (A) Two independent telomerase-null (TER1Δ) mutants were separately induced with ahTET and analyzed as for Fig. 3A. The ura4⁺ and hph⁺ ScaI bands are indicated by partial ideograms of the uncut prototelomere diagram. (B) Efficiency of prototelomere cleavage, determined as for Fig. 3C. Results from TER1Δ and wild-type (WT) strains are shown. The error bars show SEM from duplicate assays for the TER1Δ strain and triplicate assays for the WT strain. (C) The modal TRF sizes of the newly formed telomere after induction were measured as for Fig. 4C. Band sizes on these blots vary by approximately ±0.03 kb. (D) Doubling times of wild-type or TER1Δ cells bearing the 48-bp prototelomere and I-SceI expression cassette prior to ahTET induction (uninduced), 0 to 8 h postinduction, and 8 to 20 h postinduction (as determined by the OD₆₀₀).