Fig. 7: Multiple mechanisms contribute to the cell volume asymmetry between daughter cells.

A The distribution of cell volume asymmetry between daughter cells without positional bias (\(\left|\frac{{V}_{{{{\rm{D}}}}1}\,-\,{V}_{{{{\rm{D}}}}2}}{{V}_{{{{\rm{D}}}}1}\,+\,{V}_{{{{\rm{D}}}}2}}\right|\)) in the wild-type and pop-1^- (pop-1 RNAi) embryos. The cell volume asymmetry between each pair of daughter cells is averaged over eight wild^-type replicates and over two pop-1^- replicates. Based on 257 pairs of daughter cells present in all wild-type and pop-1^- embryos, the statistical significance is obtained by the one-sided Wilcoxon rank-sum test and is listed in the top right corner, along with the data average (solid dot) and standard deviation (solid line) presented. B The negative correlation between the shift of cell volume asymmetry with (\({\delta }_{{{{\rm{U}}}}-{{{\rm{C}}}}}\left[\frac{{V}_{{{{\rm{D}}}}1}\,-\,{V}_{{{{\rm{D}}}}2}}{{V}_{{{{\rm{D}}}}1}\,+\,{V}_{{{{\rm{D}}}}2}}\right]\)) and without mechanical compression (\({\left[\frac{{V}_{{{{\rm{D}}}}1}-{V}_{{{{\rm{D}}}}2}}{{V}_{{{{\rm{D}}}}1}+{V}_{{{{\rm{D}}}}2}}\right]}_{{{{\rm{U}}}}}\)). The result of proportional fitting between \({\left[\frac{{V}_{{{{\rm{D}}}}1}-{V}_{{{{\rm{D}}}}2}}{{V}_{{{{\rm{D}}}}1}+{V}_{{{{\rm{D}}}}2}}\right]}_{{{{\rm{U}}}}}\) and \({\delta }_{{{{\rm{U}}}}-{{{\rm{C}}}}}\left[\frac{{V}_{{{{\rm{D}}}}1}\,-\,{V}_{{{{\rm{D}}}}2}}{{V}_{{{{\rm{D}}}}1}\,+\,{V}_{{{{\rm{D}}}}2}}\right]\) is shown with a solid line, with the proportional coefficient (\(K\)) and goodness of fit (\(G\)) listed in the top right corner. The cell volume asymmetry between each pair of daughter cells is averaged over eight wild-type uncompressed replicates and 17 wild-type compressed replicates. The statistical significance is obtained by the one-sided Wilcoxon rank-sum test and is listed in the bottom left corner. C The apoptotic cells (vertical) are mostly smaller in volume compared to their sisters (horizontal) upon their birth. Shown are average volumes of 93 non-apoptotic and apoptotic sister-cell pairs recorded in the eight wild-type embryos, 80 of which have a relatively smaller volume for the apoptotic cells. D The illustration for asymmetric divisions of three representative parents of apoptotic cells from the AB (left), MS (middle), and C (right) lineages. For each cell, only cellular morphology at the time points before and after cytokinesis is shown. Source data are provided as a Source Data file.