Figure 3.

Uracil residues in V_H and V_κ regions from mouse germinal center B cells. (a) Rearranged mouse Igh and Igk loci. Primers were designed to amplify 500-bp fragments spanning introns downsteam of V-gene segments rearranged to J_H4 and J_κ2 gene segments, and genes encoding C_μ, and C_κ. Dotted ovals indicate the range of SHM on both loci. (b) Quantitative PCR analysis of intact DNA isolated from B220⁺GL7⁺ spleen cells of Ung^−/− and Ung^−/−Aicda^−/− mice (immunized with KLH in adjuvant), then treated with UNG and APE1; results are presented as the difference in amplification of treated versus untreated DNA, relative to Gapdh amplification. *P = 0.008 and **P = 0.001 (two-tailed t-test). Data are from six experiments (error bars, s.e.m.).