Fig 4. The strand annealing activity of Rad52 is important for preventing accelerated senescence and for the formation of type II survivors.
(A–C) Senescence rates were measured in liquid culture by serial passaging of haploid meiotic progeny of the indicated genotypes, derived from the sporulation of CCY114 (A), CCY126 (B), or CCY127 (C). Cell density was measured each day after 24 h of growth in liquid culture, followed by dilution to 2 x 105 cells/ml. Mean ± SE for each genotype is shown. At least eleven independent isolates for each genotype were followed in A, and at least four in B and C. (D) Telomere Southern blot of est2Δ and est2Δ rad52-R70A survivors obtained from the liquid culture senescence assay from A. est2Δ rad52-R70A survivors were analyzed on average 13.9 PDs after the point of maximum senescence. Type I survivors exhibit short telomeres and strong hybridization at 5.2 kb and 6.7 kb, which is due to amplification of the tandemly repeated Y′ short and Y′ long elements, respectively. The telomeres of type II survivor are extended and very heterogeneous in size.