FIG. 4.

Effect of Trolox on mitochondrial structure and mitochondrial membrane potential (Δψ) in wild-type (wt) and mitofusin knockout cells. (A) Typical examples of background-corrected and binarized microscopy images highlighting mitochondrial structure (white objects) in mouse embryonic fibroblasts (MEFs) stained with tetramethyl rhodamine methyl ester (TMRM). Wild-type (wt), mitofusin 1 and 2 double knockout (Mfn1^−/−Mfn2^−/−), mitofusin 1 knockout (Mfn1^−/−), and mitofusin 2 knockout (Mfn2^−/−) MEFs are shown. The upper and lower rows depict vehicle- and Trolox-treated cells, respectively. (B) Magnification of single cells in panel A for each condition. (C) Effect of Trolox treatment on mitochondrial length and degree of branching (reflected by the formfactor F). (D) Effect of Trolox treatment on the number of mitochondria per cell (Nc). (E) Effect of Trolox treatment on the average Δψ, as reflected by mitochondrial TMRM intensity. In this figure (C–E), significant differences with the indicated condition (a, b, c, d, e) are marked by **(p<0.01) and ***(p<0.001). The number of cells analyzed in two independent experiments equals: 96 (wt+vehicle), 104 (wt+Trolox), 127 (Mfn1^−/−Mfn2^−/−+vehicle), 95 (Mfn1^−/−Mfn2^−/−+Trolox), 103 (Mfn1^−/−+vehicle), 87 (Mfn1^−/−+Trolox), 112 (Mfn2^−/−+vehicle), and 80 (Mfn2^−/−+Trolox).