levels in fob1Δ cells were still ∼50% lower than wild type cells after aging replicatively for 50 hours, but by this age ERC levels in the fob1Δ strain had increased ∼17-fold above young wild type levels. These results indicate that ERC accumulation is an aging process that is not strictly dependent on Fob1 activity. The delayed accumulation of ERCs could reflect a reduction in the rate of formation of ERCs from the rDNA array in the fob1Δ strain, while amplification of ERCs by replication is unaffected [39].
