Figure 4.

Folate deficiency confers increased mutant frequencies in MEFs but not in brains of Ung−/− mice. A, Mouse embryonic fibroblasts were cultured in folate-deficient medium for 6 d. Average mutant frequencies at the λ cII gene (left) and individual measurements (table) are shown. B, Ung−/−(BigBlue) and Ung+/+(BigBlue) mice were fed a normal or a folate-deficient diet. Average mutant frequencies in brain tissue were assessed after 3 months. Individual measurements are given in the table. pfu, Plaque-forming unit; MF, mutant frequency.