Fig. 2

NBs are liquid organelles. a NBs are close to spherical. Distribution of axial ratios of NBs observed 12 h p.i. (20 cells and 100 NBs). The axial ratio (a/b) was determined by fitting the NB to an ellipse having the same second moments of area using the image toolbox of MatLab software (a, b: long and short axes of the ellipse). b NBs can fuse together. BSR cells infected by rCVSN2C-P-mCherry were imaged at the indicated time (lower left corner). The initial time corresponds to 15 h p.i (top row) and 18 h p.i. (bottom row). Images have been extracted from Supplementary Movies 1 and 2 and are shown at 10-sec intervals (top row) and 5-sec intervals (bottom row). Scale bars: 3 µm. c Spherical bubbles cross NBs. BSR cells infected by rCVSN2C-P-mCherry were imaged at the time indicated (lower left corner). The initial time corresponds to 16 h p.i. Images have been extracted from Supplementary Movie 3 and are shown at 5-s intervals. Scale bar: 3 µm. d NBs are sensitive to a hypotonic shock. BSR cells infected by rCVSN2C-P-mCherry were imaged. A hypotonic shock was applied at indicated t = 0 (corresponding to 18 h p.i.). Images are shown at 2-min intervals. Images have been extracted from Supplementary Movie 4. Scale bar: 15 µm. e–h Fluorescence recovery after photobleaching (FRAP) of P-mCherry in BSR cells at 37 °C. The diameter of the photobleached regions was 2.7 µm. e–g FRAP data were corrected for background, normalized to the minimum and maximum intensity. The mean is shown with error bars representing the SD. Experimental curves were fitted with a two-exponential model (in black). e Cytosolic P-mCherry expressed in BSR-T7/5 cells was photobleached 24 h after transfection of pTit-P-mCherry plasmid. Data were from 11 FRAP events (Supplementary Fig. 2). f Cytosolic P-mCherry expressed in BSR cells infected by rCVSN2CΔG-P-mCherry was photobleached 16 h p.i. Data were from 13 FRAP events (Supplementary Fig. 3). g P-mCherry localized in NBs in BSR cells infected by rCVSN2CΔG-P-mCherry was photobleached 16 h p.i. Data were from 12 FRAP events (Supplementary Fig. 4). h Fluorescence recovery profile along a diameter of a photobleached NB as in g