Mitochondria from different tissues were isolated using standard differential centrifugation methods reported by Hogeboom (61 ) with slight modifications described in SI Appendix, section S4. Mitochondria were isolated from tissues of 18-d mouse embryos as described previously (62 (link)). The respiratory activity of isolated mitochondria was measured polarographically with a Clark-type electrode as described previously (45 ). The mitochondrial membrane potential, Δψ, was analyzed in a mitochondrial suspension by monitoring changes in the fluorescence of the lipophilic cationic dye safranin O, using a previously described method (63 (link)). The protein concentrations of the samples were measured using the Lowry method. Western blot analyses of protein extracts of fractionated tissues were performed as described previously (64 (link)). Hydrogen peroxide production by the mitochondria was estimated using the method reported by Zhou et al. (65 (link)), with modifications described in our previous study (66 (link)). Total RNA was extracted using Extract RNA Reagent (Evrogen). RT-PCR was performed on individual cDNAs using 5× SYBR Green Mix (Evrogen) and a DT-96 thermocycler (DNA Technology). The hexokinase assay was based on the method reported by Scheer et al. (67 (link)). Catalase, SOD, GPx1, and GR activities; lipid peroxidation and protein carbonylation assays; and the levels of total glutathione and the ratio of reduced to oxidized glutathione were estimated using special kits according to protocols provided by Abcam. Primary cultures of hepatic fibroblasts and confocal microscopy were performed as described previously (68 (link)) and in SI Appendix, section S5. Data are presented as mean ± SD or SEM as applicable. All calculations were performed using GraphPad Prism 7.0. Detailed protocols are provided in SI Appendix, Materials and Methods.