Somatic mutation frequency and percentage of genome rearrangements increases in blm mutants with age. (a) Somatic mutation frequencies grouped by sex and age. Each bar represents five to seven independent measurements. Error bars represent standard deviations. *P < 0.05 compared to wild type, **P < 0.01, ***P < 0.001 (one-way ANOVA). (b) Somatic mutation frequencies in various body regions. Samples of head, thorax, and abdominal tissue were collected from 35-day-old male and female flies and somatic mutation frequencies were determined. Each bar represents three to six independent measurements. Error bars represent standard deviations. **P ≤ 0.01 compared to wild type (two-tailed unpaired t-test). (c) Somatic mutation frequencies that involved either a size change or no size change, grouped by sex and age. Size change mutations correspond to genome rearrangements or lacZ internal deletions, while no size change mutations are usually point mutations.