Figure 3.

RI and mass density distributions in HeLa-FUCCI (a–c) and RPE-FUCCI (d–f) cells as a function of the cell cycle. (a and d) Shown are cross-sectional slices of 3D RI tomograms of cells in the x-y, x-z, and y-z planes. The dashed lines indicate the corresponding x-z and y-z planes. The color scale quantifies the RI, n. Scale bars, 20 μm. (b–e) Shown are the corresponding FUCCI-fluorescence images of nuclei in different cell cycle phases. Red color identifies cells in the G1 phase of the cell cycle, yellow in early S, and green in S/G2. (c–f) Given is the ratio of the mass density between nucleoplasm/cytoplasm (ρ_np/ρ_c), nucleoplasm/perinuclear cytoplasm (ρ_np/ρ_pc), and nucleoli/nucleoplasm (ρ_nl/ρ_np). The dashed lines indicate equal mass density between compartments. The colors indicate cell cycle phases as in (b) and (e). The numbers of cells measured are N = 557, 505, and 483 for HeLa cells and N = 122, 92, and 128 for RPE cells in the G1, early S, and S/G2 phases, respectively. (g) Given is a schematic indicating the four segmented regions and how they scale in size to maintain the same relative mass densities throughout the cell cycle. To see this figure in color, go online.