Figure 4. The distance between mother and daughter centrioles increases during the cell cycle in a Plk1-dependent manner.

(a) Electron micrographs of duplicated centrioles with the daughter centrioles of various lengths. Daughter centrioles from cycling S and G2-phase-arrested cells and from cells arrested in the S phase by hydroxyurea (HU) are positioned closer to the walls of the mother centrioles than the daughter centrioles in prometaphase and metaphase cells. After inhibition of endogenous Plk1 for 4 h before mitotic entry, daughter centrioles remain close to the mother centrioles during prometaphase. The same is true for the centrioles in post-mitotic cells, if Plk1 is inhibited 7 h before mitotic entry. Scale bar, 200 nm. (b,c) Graph showing the correlation between mother–daughter centriole wall-to-wall distance and daughter centriole length. Wall-to-wall distance and the length of daughter centrioles were measured from electron micrographs. Points marked in yellow were measure from electron micrographs from refs 1, 18, 19, 20. Each dot on the graph represents one centriole pair. (c) Histogram represents average wall-to-wall centriole distance under various experimental conditions. Error bars are the s.d. The statistical significance between the data sets was determined by a two-tailed t-test using Microsoft excel. NS, not statistically different, ***P≤0.001.