Correlations between area-gradients of sibling cells.

<p>The area gradient is computed by applying a median filter (size 12 measurements) over each track's size measurements, to reduce noise. A line was then fitted to the resultant points and the gradient of the line is reported. This measures the rate of growth rather than overall size attained. Regardless of generation, there are strong positive correlations between siblings when both siblings divide (A). When one sibling dies and another divides (B), the rates of growth are only weakly correlated. Since the gradient is computed throughout the life of the cell, this suggests that fate determines cell growth early in the life of the cell reducing growth of the dying cell compared to its sibling. In the case of both siblings dying (C), both siblings rates of growth are clustered around zero with a slight positive correlation, although as discussed in section 2.4 any apparent growth in the final generation may be an artefact of increased fluorescence intensity and automatic segmentation. Panel (D) shows correlations for all fate combinations, an intermediate correlation as expected because the division correlation is diluted.