Figure 3.

Loss of 53BP1 leads to increased end resection. (A) Schematic representation of IgH^I-96k allele (top) with the PCR primers used to amplify a 336-nt recombination product, indicated as arrows (bottom). LoxP sites are indicated as red triangles, and I-SceI sites are indicated as blue circles. (B) Representative ethidium bromide–stained argarose gels showing PCR products obtained after I-SceI–induced recombination in IgH^I-96kAID^−/− and IgH^I-96kAID^−/−53BP1^−/− B cells. (C) Bar graphs showing frequency of I-SceI–induced recombination products running ≤300 nt for IgH^I-96kAID^−/− and IgH^I-96kAID^−/−53BP1^−/− B cells, determined by 12 independent PCR experiments. Error bars indicate standard deviation. The p-value was calculated using a two-tailed Student’s t test. (D) Dot plot showing total resection of I-SceI–infected IgH^I-96kAID^−/− and IgH^I-96kAID^−/−53BP1^−/− B cells. Each dot represents one sequence. The p-value was calculated using a two-tailed Student’s t test. The means are shown as horizontal lines. (E) Bar graph shows the frequency of perfect I-SceI joins in I-SceI–infected IgH^I-96kAID^−/− and IgH^I-96kAID^−/−53BP1^−/− B cells in five independent experiments. Error bars indicate standard deviation. The p-value was calculated using a two-tailed Student’s t test.