Figure 1. ETI Mother Cells Show a Non-progressive Cell Cycle Length Phenotype and Reduced Lifespan that is Rescued by SML1 Deletion.

Mother cell budding profiles for (A) WT, (B) tlc1Δ, (C) est2-D530A, (D) tlc1Δsml1Δ, showing cell cycle durations and heterogeneity (see exponential color scale, cell cycles with durations 1.4 hours or less were colored in purple). The x-axis displays individual mother cells shown as vertical bars with budding events indicated as horizontal white divisions. Mean lifespan for each genotype is presented in the upper left corner of the plot. (E) ETI mother cells showed reduced replicative lifespans compared to WT cells (number of cells (n): tlc1Δ, 354; est2-D530A, 117; WT, 234. p-value for difference between tlc1Δ and WT < 1e-37). (F) Deletion of Sml1 restores lifespan of ETI mother cells to WT levels (n: tlc1Δsml1Δ, 77; sml1Δ, 39). (G) The heterogeneity of cell cycle lengths in ETI cells did not progressively worsen relative to WT as mother cells aged. Fold increase in cell cycle variability from 1^st and 2^nd to 3^rd and 4^th last cell cycles compared for each genotype (shown below each set). The variance of 1^st and 2^nd cell cycles of tlc1Δ and est2530A is significantly greater than that of WT (F-test p-value < 1e-16 and 1e-13 respectively).