Figure 1. Senescence of telomerase-negative strains in the presence and absence of Ctf18.
[A]: Senescence assay growth curve generated during 196 (11 rounds) of repetitive subculturing for wild type, mre11A470Ttlc1▵, ctf18▵ and mre11A470T ctf18▵ strains. Colonies from freshly dissected spores were incubated on YPD plates for 18 hours at 30°C and then inoculated into 5 ml YPD, grown at 30°C for 18 hours [36 hours after dissection], and counted using a hemocytometer. Each subsequent round of subculturing [hours 54–198] was initiated by inoculating fresh medium with 1×105 cells/ml from the previous subculturing at 30°C. [B]: Telomere lengths of the strains in [1A] after 36 and 54 hours of growth after dissection at 30°C. The samples shown on the gel were derived from the cells grown in [1A]. Telomere sizes were determined by digestion of genomic DNA with XhoI followed by Southern analysis using poly GT as a telomeric probe.