rDNA is the major regulator of replicative lifespan in the RM/BY cross.

<p>(A) Replicative lifespans (RLS) of the RM and BY parental strains and 88 segregant strains were determined by mother-daughter separation on YPD plates. The mean RLSs were determined by examining 20 cells of each strain. (B) A genome-wide scan to find loci that contribute to lifespan reveals a maximum LOD score centered on the rDNA locus on chromosome XII. RLS distributions of strains inheriting the BY or RM rDNA loci are shown in the inset. Average RLS for strains with BY rDNA was 23.5±4.6 and average RLS for strains with RM rDNA was of 33.1±7.0 (<i>P</i> = 9.5×10⁻¹², ν = 88). (C) RLS curves (n = 40 cells) for the BY parent and the backcrossed BY strain with RM rDNA (<i>P</i> = 10⁻³, ν = 2). (D) RLS curves (n = 40 cells) for the RM parent and backcrossed RM strain with BY rDNA (<i>P</i> = 5.0×10⁻³, ν = 2). Mean RLS for backcross strains are indicated in parentheses (C, D).