Figure 4.—

A novel recombinant is associated with the bypass of senescence. (A) Southern analysis of DNA isolated from subcultured tlc1Δ or an MRE11 TLC1 control strain after digestion with XhoI and hybridization, using poly d(GT)/d(CA) as the telomeric probe. The degree of subculturing (s0–s7) is shown above the relevant lanes of the gel. (B) Southern analysis of DNA isolated from a subcultured (s0–s7) mre11-A470T tlc1Δ spore colony or an MRE11 TLC1 control strain carried out as described above. A size ladder (in kilobases) is at the left of the gel. Drawing to the right of each gel depicts the distributions exhibited by type 1 (A) and type IA (B). The numbers below the blots reflect the ratio of Y′ repeat hybridization signal to a single-copy LEU2 probe normalized to a value of 1.0 for the first subculture. Arrows on the right in B indicate the positions of the subtelomeric Y′ repeats.