(A) Effect of the rad54∆ and rad52∆ mutations in spontaneous and UV-induced uSCE. The frequency of spontaneous and UV-induced recombinants was determined by irradiating or not cells plated onto solid medium after the corresponding dilutions (SMM and SMM without histidine to calculate total and recombinant cells, respectively). The mean and SEM of 3-5 independent fluctuation tests are shown. Asterisks indicate statistically significant differences according to an unpaired two-tailed Student's t-test. Two and three asterisks represent p-values <0.01 and <0.001, respectively. 