Telomere length and DNA damage foci in <i>Nth1^+/+Tert^−/−</i> and <i>Nth1^−/−Tert^−/−</i> mouse cells.

<p>(A) Q-FISH analysis of bone marrow cells derived from <i>Nth1^+/+ Tert^−/−</i> and <i>Nth1^−/−Tert^−/−</i> mice (n = 8). Representative quantitative measurement of telomere signal intensity is shown in jitter plot displaying complete distribution of telomeres with diverse signal intensity (left panel) and in a combined histogram displaying relative frequency of telomeres plotted against telomere signal intensity (right panel). Bars (in green) denote mean telomere signal intensity. (B) Representative metaphase spreads from indicated genotypes, showing enlarged chromosome ends with or without telomere signals (Normal and SFE, respectively). Arrows depict SFEs. (C) Quantification of SFEs in bone marrow cells with indicated genotypes (8 mice). At least 50 metaphases/sample are counted. Values depict mean values ± SD from each sample. P-values are calculated using a Student's <i>t</i>-test. * represents P = 0.01. (D–E) Percentage of <i>Nth1^+/+ Tert^−/−</i> and <i>Nth1^−/−Tert^−/−</i> cells with various numbers of γ-H2AX foci in the genome and telomeres by IF and IF-telomere FISH analysis, respectively. At least 100 cells/sample are counted. Error bars indicate standard deviation.