Figure 3. High copy expression of RNR1 extends chronological lifespan. (A) CLS determined by measuring colony-forming units (cfus) of wild-type (W303) cells transformed with a high copy plasmid expressing RNR1 or the empty vector. (B) DNA content of wild-type cells transformed with the plasmid expressing RNR1 or the empty vector after 5 d of medium depletion. (C) CLS of wild-type and mec1-21 cells transformed with the plasmid expressing RNR1 or the empty vector. (D) % visibly budded cells in the cultures described in panel (C). Data in panels (A–C) are representative of results from two or more independent experiments.