Fig. 5. Effect of RA-induced differentiation on the mtDNA copy number/cell and expression of Polg, Polg2 and Tfam (days 1-7). (A) The number of mtDNA molecules/cell was determined using real-time PCR and normalised to the Gapdh gene. The x axis is as in B. (B) Polg, Polg2 and Tfam expression in undifferentiated (Und) and RA-induced D3 mESCs. RT-PCR relative quantification compared the expression of individual genes to their expression in undifferentiated D3 mESCs. Values for each gene were normalised to Gapdh expression. Bars represent mean ± s.e.m. Significant differences between undifferentiated and days 1, 3, 4 and 6 are indicated above the respective bar representing the stage of differentiation; the significant difference between days 3 and 7 is shown next to the connecting line (*P<0.05, **P<0.01, ***P<0.001).