Fig. 4: Impact of obesity on fasting-feeding dynamics of ER, mitochondria, and their interactions in liver tissue.

A Number of mitochondria in individual hepatocytes from mice in fed and fasted state (n = 5 cells in each condition). B Left: SEM image (scale bar: 500 nm); Right: 3D segmentation and reconstruction of individual mitochondria in fed state (scale bar: 1 µm). C Left: SEM image (scale bar: 500 nm); Right: 3D segmentation and reconstruction of individual mitochondria in fasted state (scale bar: 1 µm). D Left: Mitochondria volume; Right: 95% of confidence interval for data in D. E Mitochondria volume frequency distribution. F Left: Mitochondria sphericity; Right: 95% of confidence interval for data in F. G Mitochondria sphericity frequency distribution. H 3D Reconstruction of mitochondria volumes marked by areas of interactions with the ER at 0–24 nm distance (red) lean fed, lean fasted, obese fed and obese fasted state conditions. Scale bars: 1 µm. I Quantification of the % of mitochondria surface covered by ER at 0–24 nm distance in the same conditions described in H. J Frequency distribution of % of mitochondria covered by ER at distances indicated in the graphs. K 3D Reconstruction of mitochondria volumes marked by areas of interactions with the ER at 24-56 nm distance (purple) lean fed, lean fasted, obese fed and obese fasted state conditions. Scale bars: 1 µm. L Quantification of the % of mitochondria surface covered by ER at 24-56 nm distance in the same conditions described in K. M Frequency distribution of % of mitochondria covered by ER at distances indicated in the graphs. For (D–G) number of mitochondria are fed, n = 17,721 mitochondria and fasted, n = 12,712 mitochondria. For (I, L), lean fed (n = 3173, 3000, 3109, 2787, 2787), lean fasted (n = 894, 1183, 1275, 1246, 757, 1323), obese fed (n = 2084, 5054, 3854, 3521, 3201) and obese fasted (n = 3250, 2781, 2607, 2065, 1999) states. For (J, M), lean fed (n = 2766), lean fasted (n = 1275), obese fed (n = 3851), obese fasted (n = 2586) states. Obese: leptin-deficient mice, ob/ob. Fasted state corresponds to 20 h (overnight) food withdrawal. For the bar graph in A, data is shown as mean ± s.e.m; For D and F, two-tailed, unpaired t-test ****p < 0.0001 and permutation test ****p < 0.0001.