Fig. 4.

Effects of lifespan-extending mutations on rDNA silencing. (A) The rDNA silencing reporter parent strain, JS128, and isogenic deletion strains hxk2Δ and fob1Δ, were grown up in YPD. These were then diluted in H₂O and serially spotted out on synthetic complete media (SC), SC − ura media (−ura) and SC + FOA media (FOA) containing 2% glucose. Spots correspond to OD₆₀₀ = 1 (left) then serial 1 in 5 dilutions to the right. Plates were imaged after 2 days at 30 °C. Reduced growth on −ura compared with SC indicates increased silencing in this assay. (B) The JS122 control strain, where URA3 is integrated in a nonsilenced locus, and isogenic deletion strains comprising hxk2Δ and fob1Δ, were grown up in YPD and plated exactly as above. (C) The telomeric silencing reporter parent strain, AEY1017, and its isogenic deletion strains, hxk2Δ and fob1Δ, were grown up in YPD, plated as above and imaged after 3 days. Reduced growth on FOA is a readout of reduced silencing in this assay.