Figure 1.

The stage of the cell cycle determines whether taz1^- cells sustain telomere fusions. (A) Diagram of telomeric NotI restriction fragments on chromosome I and II (C, I, L, and M); chromosome III lacks NotI restriction sites. (B,C) Southern blot analysis of genomic DNA digested with NotI, separated by PFGE, and probed with a telomeric oligonucleotide. Telomeric restriction fragments are indicated. C^* comprises the C restriction fragment as well as the C + L, C + M, and C + I fusions that cannot be resolved under these conditions. (B) Inactivation of wee1⁺ extends early G1 and induces fusions of taz1^- telomeres during logarithmic growth. The most prominent fusion band (top arrow) corresponds to circularized chromosome I. Prolonged growth of wee1^ts cells at the semipermissive temperature typically distorts the FACS profile due to delayed cytokinesis in small cells. (C) rum1⁺ deletion prevents G1 arrest during nitrogen starvation, and prevents starvation from inducing fusion between taz1^- telomeres.