Es each obtained using a different emission wavelength of fluorescence from a single image field. These two channel files show the cellular probes/organelles used as references: (i) anti-tubulin antibody as internal control and marker of microtubules and (ii) DAPI for the nucleus. Each 1379592 of the field images is of size 172861728 for the first three cell lines and 204862048 for the rest of eight, and the pixel size is 0.08 microns in the sample plane. The field images were then also downsampled for EPZ015666 site computational efficiency to 0.2 microns.Computational MethodsCell segmentation for cell size calculation and 3D morphology generation. The field images were segmentedMaterials and Methods Data Acquisition3D image data of HeLa cells. We used 3D images of HeLa cells previously obtained by three color confocal immunofluores-into single cell regions using a seeded watershed method on the tubulin channel with the nuclei in the nuclear channel as seeds. The 2D cell and nuclear boundaries were found by thresholding the single cell regions and the nuclei respectively. These were usedFigure 9. Scatter plot of the estimated total amount of polymerized tubulin versus the area of cytosolic space (sum of pixels) for real cells from eleven cell lines. The correlation coefficient for each cell line is shown in the legend. doi:10.1371/journal.pone.0050292.gComparison of Microtubule Distributionsfor cell size calculation and for 3D morphology generation (see below). Point Spread Function (PSF) estimation. The confocal PSF was generated computationally based on a theoretical model using the SVI PSF calculator for the Zeiss LSM 510 confocal microscope for the first three cell lines and the Leica SP5 for the other eight cell lines (http://www.svi.nl/NyquistCalculator). The pinhole size was set to 1 Airy Unit for the Zeiss and 285.16 nm for the Leica. The numerical aperture was 1.4 and the emissionexcitation data used to generate the PSF was for the Alexa555 dye (http://probes.invitrogen.com/handbook/boxes/0442.html). The PSF is used to convolve on the generated raw image of distribution of microtubules to account for the digital blurring from microscopy imaging. Centrosome location MedChemExpress Epoxomicin detection. The 3D coordinate of the centrosome was estimated by breaking the problem into two parts. First, the XY-coordinate was estimated and then the Z-coordinate. The XY-coordinate was chosen as the pixel with the maximum intensity value in the vicinity of the nucleus after smoothing with an averaging filter of size 25 pixels on the tubulin channel image (as for cell image). For the Z-coordinate, we used linear regression to estimate the location as a function of the following predictor variables: (i) Maximum intensity of the microtubule image, (ii) Mean intensity of the microtubule image, and (iii) pixel intensity of the XY coordinate in the microtubule image. The coefficients of the linear regression were estimated from the 3D HeLa images where the 3D centrosome as described previously [8]. The estimated centrosome is then used to act as an organizer for microtubules and all generated microtubules start from it. Estimation of single microtubule intensity. The single microtubule intensity for each cell line was estimated using the method described previously [9]. It is then used to scale the intensity of synthetic image up to that of the real image. 3D cell and nuclear morphology generation. In order to estimate the cell shape, we firstly required the following two estimates: (1) the.Es each obtained using a different emission wavelength of fluorescence from a single image field. These two channel files show the cellular probes/organelles used as references: (i) anti-tubulin antibody as internal control and marker of microtubules and (ii) DAPI for the nucleus. Each 1379592 of the field images is of size 172861728 for the first three cell lines and 204862048 for the rest of eight, and the pixel size is 0.08 microns in the sample plane. The field images were then also downsampled for computational efficiency to 0.2 microns.Computational MethodsCell segmentation for cell size calculation and 3D morphology generation. The field images were segmentedMaterials and Methods Data Acquisition3D image data of HeLa cells. We used 3D images of HeLa cells previously obtained by three color confocal immunofluores-into single cell regions using a seeded watershed method on the tubulin channel with the nuclei in the nuclear channel as seeds. The 2D cell and nuclear boundaries were found by thresholding the single cell regions and the nuclei respectively. These were usedFigure 9. Scatter plot of the estimated total amount of polymerized tubulin versus the area of cytosolic space (sum of pixels) for real cells from eleven cell lines. The correlation coefficient for each cell line is shown in the legend. doi:10.1371/journal.pone.0050292.gComparison of Microtubule Distributionsfor cell size calculation and for 3D morphology generation (see below). Point Spread Function (PSF) estimation. The confocal PSF was generated computationally based on a theoretical model using the SVI PSF calculator for the Zeiss LSM 510 confocal microscope for the first three cell lines and the Leica SP5 for the other eight cell lines (http://www.svi.nl/NyquistCalculator). The pinhole size was set to 1 Airy Unit for the Zeiss and 285.16 nm for the Leica. The numerical aperture was 1.4 and the emissionexcitation data used to generate the PSF was for the Alexa555 dye (http://probes.invitrogen.com/handbook/boxes/0442.html). The PSF is used to convolve on the generated raw image of distribution of microtubules to account for the digital blurring from microscopy imaging. Centrosome location detection. The 3D coordinate of the centrosome was estimated by breaking the problem into two parts. First, the XY-coordinate was estimated and then the Z-coordinate. The XY-coordinate was chosen as the pixel with the maximum intensity value in the vicinity of the nucleus after smoothing with an averaging filter of size 25 pixels on the tubulin channel image (as for cell image). For the Z-coordinate, we used linear regression to estimate the location as a function of the following predictor variables: (i) Maximum intensity of the microtubule image, (ii) Mean intensity of the microtubule image, and (iii) pixel intensity of the XY coordinate in the microtubule image. The coefficients of the linear regression were estimated from the 3D HeLa images where the 3D centrosome as described previously [8]. The estimated centrosome is then used to act as an organizer for microtubules and all generated microtubules start from it. Estimation of single microtubule intensity. The single microtubule intensity for each cell line was estimated using the method described previously [9]. It is then used to scale the intensity of synthetic image up to that of the real image. 3D cell and nuclear morphology generation. In order to estimate the cell shape, we firstly required the following two estimates: (1) the.