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DNA fragmentation was investigated in MCF7 and the MCF7TAX19 paclitaxel-resistant subline exposed to paclitaxel for 24 h. No nucleosome-sized DNA fragmentation was observed by DNA agarose gel electrophoresis in both cell lines. However, DNA fragmentation was detected by flow cytometry sub-G1 peak analysis in both cell lines immediately after paclitaxel exposure. Nuclear abnormalities were observed in both cell lines in the range of 35-40% of the total cell population. This value was reached immediately in MCF7 cells but was time-delayed in MCF7TAX19 cells. Significant morphologic differences were observed between sensitive and resistant cell lines, 24 h after exposure to 50 nmol/l paclitaxel. Although no difference in the sub-G1 cell population was observed between sensitive and resistant cells, a significantly higher rate of multinucleated cell features was observed in resistant cells.

International audienceExcept for blind methods, deconvolution of 3-D data sets acquired from a fluorescence microscope requires the knowledge of the point spread (PSF) of the instrument. Unsing the XCOSM package, we show first with simulations and then with recorded data that it is possible to recover from an experimental PSF some parameters, which are very difficult or impossible to measure during the acquisition, like the specimen depth or the immersion medium refractive index. Doing so, we can precise the acquisition protocol, which helps to use the instrument under optimal conditions. Furthermore, the knowledge of the actual acquisition condtions permits to use fo the deconvolution process a computed PSF, which is noiseless and as close as possible to the actual PSF. This helps to reduce errors in quantitative measurements after deconvolution, as shown with computations

3-D optical fluorescent microscopy becomes nowadays an efficient tool for volumic investigation of living biological samples. Using optical sectioning technique, a stack of 2-D images is obtained. However, due to the nature of the system optical transfer function and non-optimal experimental conditions, acquired raw data usually suffer from some distortions. In order to carry out biological analysis, raw data have to be restored by deconvolution. The system identification by the point-spread function is useful to obtain the knowledge of the actual system and experimental parameters, which is necessary to restore raw data. It is furthermore helpful to precise the experimental protocol. In order to facilitate the use of image processing techniques, a multi-platform-compatible software package called VIEW3D has been developed. It integrates a set of tools for the analysis of fluorescence images from 3-D wide-field or confocal microscopy. A number of regularisation parameters for data restoration are determined automatically. Common geometrical measurements and morphological descriptors of fluorescent sites are also implemented to facilitate the characterisation of biological samples. An example of this method concerning cytogenetics is presented.