Hyperactivation of DNA-PK by double-strand break mimicking molecules disorganizes DNA damage response.

Cellular response to DNA damage involves the coordinated activation of cell cycle checkpoints and DNA repair. The early steps of DNA damage recognition and signaling in mammalian cells are not yet fully understood. To investigate the regulation of the DNA damage response (DDR), we designed short and stabilized double stranded DNA molecules (Dbait) mimicking double-strand breaks.

The Dogfish Scyliorhinus canicula: A Reference in Jawed Vertebrates.

INTRODUCTIONDue to their large size and long generation times, chondrichthyans have been largely ignored by geneticists. However, their key phylogenetic position makes them ideal subjects to study the molecular bases of the important morphological and physiological innovations that characterize jawed vertebrates. Such analyses are crucial to understanding the origin of the complex genetic mechanisms unraveled in osteichthyans.

Quantitative fluorescence imaging approach for the study of polyploidization in hepatocytes.

We applied automatic quantitative fluorescence imaging of nuclear DNA to rat liver cells obtained from animals at various times after birth up to 3 months of age. We show that, in conditions best preserving the native cellular structures, DNA content measurements, performed on whole single cells in situ after Hoechst staining, were precise and accurate. Cells in the various ploidy and nuclearity classes could thus be identified correctly and their percentages were estimated on a total of 300 cells or more.

DNA content by in situ fluorescence imaging and S-phase detection, with chromatin structure preserved.

Objective: To test the feasibility of in situ DNA quantitation of adherent cells' nuclei by fluorescence imaging, preserving chromatin structure and to follow-up S phase, in relation to DNA content, in order to assess the precision of DNA measurements.

Study Design: Double labeling experiments involved total DNA staining with Hoechst 33342 and BrdU immunostaining (after either Br photolysis and DNA strand break labeling by terminal transferase or acid denaturation) to detect replicating DNA. An epifluorescence microscope was used, images captured with a CCD camera and quantitative total DNA measurements done in 12 bits with IPLab software.

SIAH-1 inhibits cell growth by altering the mitotic process.

SIAH-1, the human homologue of the drosophila seven in absentia gene, is a p53-p21Waf-1 inducible gene. We report that stable transfection with SIAH-1 of the epithelial breast cancer cell line MCF-7 blocks its growth process. The transfectants show a redistribution of SIAH-1 protein within the nucleus, more specifically to the nuclear matrix, associated to dramatic changes in cell morphology and defective mitosis.