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. 2019 Nov 12;8:e50778. doi: 10.7554/eLife.50778

Figure 4. Disruption of homologous repair by deletion of RAD52 causes constant high rate of GLMs during aging.

(A) Rad52∆ mutants have a constant high rate of GLMs but do not show a significant age-related increase in GLMs (p>0.05 cochran q test). Lifespan only shown 0–15 divisions due to reduced lifespan of rad52∆ mutants. (B) Survival curve showing the significant increase in GLM rates in individual rad52∆ mother cells. Each row is a separate mother cell, and the color indicates whether a cell experienced a normal cell cycle, GLM or terminal missegregation (n = 100 randomly selected cells). (C) Rad52∆ cells are more likely than wild-type to experience a terminal GLM, but any individual GLM is not more likely to result a terminal missegregation. This suggests Rad52 is important for preventing GLMs, but not for ensuring genomic content is properly segregated. (D) Cells lacking RAD52 have a statistically significant increase in the length of time a GLM lasts relative to wild-type cells (n is the number of cell cycles quantified, p<0.01 Students t-test).

Figure 4.

Figure 4—figure supplement 1. Cdc14 single cell traces showing terminal and corrected GLM events.

Figure 4—figure supplement 1.

(A) Schematic showing cell cycle dynamics. Cdc14 is localized to the nucleolus during the majority of the cell cycle and exits it in two stages during mitosis to initiate anaphase. Cdc14 re-enters the nucleolus at the end of mitosis. (B) A representative trace of a single cell expressing Htb2:mCherry and Cdc14:GFP showing normal divisions and GLMs that are corrected. Histone levels (pink) increase, and then fall during mitosis. Arrows indicate the timepoints where Cdc14 is at a minima in the nucleolus. In normal divisions this coincides with the Htb2 minima. (*) indicate raw Htb2 and Cdc14 measurements, which were smoothed using a moving average and Savitzky-Golay smoothing respectively for legibility (solid lines). In the last two divisions, GLMs can be observed. (C) Representative trace of a single cell expressing Htb2:mCherry and Cdc14:GFP showing a terminal GLM. Cdc14 exits the nucleolus nearly eight hours after the GLM. (D) Representative trace of a single cell expressing Htb2:mCherry and Cdc14:GFP showing a GLM that is corrected (4 hr) and then a terminal GLM (9 hr).