Rapid Analysis of Chromosome Aberrations in Mouse B Lymphocytes by PNA-FISH

Defective DNA repair leads to increased genomic instability, which is the root cause of mutations that lead to tumorigenesis. Analysis of the frequency and type of chromosome aberrations in different cell types allows defects in DNA repair pathways to be elucidated. Understanding mammalian DNA repair biology has been greatly helped by the production of mice with knockouts in specific genes. The goal of this protocol is to quantify genomic instability in mouse B lymphocytes. Labeling of the telomeres using PNA-FISH probes (peptide nucleic acid - fluorescent in situ hybridization) facilitates the rapid analysis of genomic instability in metaphase chromosome spreads. B cells have specific advantages relative to fibroblasts, because they have normal ploidy and a higher mitotic index. Short-term culture of B cells therefore enables precise measurement of genomic instability in a primary cell population which is likely to have fewer secondary genetic mutations than what is typically found in transformed fibroblasts or patient cell lines.     

Kinetochore stretching-mediated rapid silencing of the spindle-assembly checkpoint required for failsafe chromosome segregation

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Impact of sewage pollution on two species of sea urchins in the Mediterranean Sea (Cortiou,France): Radial asymmetry as a bioindicator of stress

BackgroundThe surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.MethodsWe used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs and primary tubercles.ResultsFor both species, the most polluted sampling site, Cortiou, displayed the highest level of FA, while the Maire and East Maire sampling sites displayed the lowest levels. A. lixula revealed systematic differences in FA among sampling sites for all characters and P. lividus showed differences in FA for the number of primary tubercles.ConclusionsStatistical analyses of FA show a concordance between the spatial patterns of FA among sampling sites and the spatial distribution of sewage discharge pollutants in the Cortiou area. High developmental stress in these sampling sites is associated with exposure to high concentrations of heavy metals and many harmful organic substances contained in wastewater. FA estimated from structures with complex symmetry appears to be a fast and reliable tool to detect subtle differences in FA. Its use in biomonitoring programs for inferring anthropogenic and natural environmental stress is suggested.