Fig. 2: Cell survival is correlated.
a Labeling scheme of relationship. The first number in the square bracket is the number of generations to go up to a common ancestor, and the second is the number to go down to get to the related cell. The sum of these two numbers is equal to the conventional degree of separation. b, c Pearson correlation of the survival parameter, X, for wild-type (WT, red) and ΔtolC (green) strains. The lines are from the model fit; see Fig. 4 for the model. In WT, the correlation was the highest between sibling cells and decreased for distant relationships. The decrease was more gradual in the ΔtolC strain. Three biological repeats were conducted. Small open circles indicate data from each replicate. The horizontal bars indicate their weighted means. The number of cells with known fates (used to calculate the correlation) differed between the replicates; the three biological replicates yielded 2529, 5737, and 4246 cells with known fates for WT, and 2535, 2261, and 10070 cells for ΔtolC. The brackets indicate the relationship with equal degrees of connection. To statistically assess whether the obtained correlation coefficients are significantly greater than zero (i.e., no correlation), we performed linear regression analyses on the survival parameters (X) between related cells and calculated corresponding p-values; see Supplementary Text 3.1. d We sorted cells according to cell age, Z, and calculated the survival <X > Z for different ages. The population-mean survival <X> was subtracted: <X > = 0.66 for WT and 0.64 for ΔtolC. Small open circles indicate <X > Z − < X> for each biological replicate. Solid red circles or green squares indicate the mean of these replicates (for WT and ΔtolC, respectively). To calculate the error bar, we compared the standard deviation of data from three biological replicates and the standard error for a binomial distribution with the number of cell pairs used and plotted whichever was larger. The plot shows that <X > Z − < X> increases with increasing Z. The slope of this increase was found to be 0.0168 ± 0.0035 for WT, and 0.0118 ± 0.0033 for the ΔtolC strain. See Supplementary Text 3.2 for statistical analysis.
