Fig. 5: Identification of mitochondrial “cut-through crista”.

A Focused ion beam/scanning electron microscopy (FIB-SEM) image of mitochondria in HeLa cells. 3D reconstruction and segmentation of mitochondrion showing normal crista and cut-through crista from FIB-SEM were completed by using 3D-IMOD software. White, mitochondrial outer membrane; cyan, mitochondrial IBM and “cut-through crista”; purple red, lamellar crista. B Quantification of the “cut-through crista” in mitochondria of HeLa cells (n = 100 cristae). Error bars indicate the means ± SD of three independent experiments. C Live OPA1 KO MEFs were stained with MitoTrack Green and then imaged by Hessian-SIM. D The 70 nm section of specimen of HCT116 OPA1 KO cells was analyzed and imaged by Fei Tecnai Spirit Transmission Microscope. 3D reconstruction and segmentation of mitochondrion were completed using 3D-IMOD software. Blue, mitochondrial outer membrane; cyan, mitochondrial IBM and “cut-through crista”; green, onion-like crista; purple red, tubular crista. E Representative thin-section FIB-SEM images of mitochondrion showing cut-through crista with 2 crista junctions in HCT116 OPA1 KO cells. 3D tomographic reconstruction and segmentation of OPA1 KO mitochondrion from FIB-SEM were performed by using 3D-IMOD software. White, mitochondrial outer membrane; cyan, mitochondrial IBM and “cut-through crista”. F Quantification of the “cut-through crista” in mitochondria of control and OPA1 KO HCT116 cells (n = 100 cristae). “others” means “other types of crista except for cut-through crista”. Statistical significance was assessed from the student’s t-test; error bars indicate the means ± SD of three independent experiments, **p < 0.01 versus control. G The continuous 10 nm-thick sections (total 300 nm) from Mic10 KO HeLa cells were analyzed and imaged by FIB-SEM. 3D tomographic reconstruction and segmentation of mitochondrion from FIB-SEM were performed by 3D-IMOD software. White, mitochondrial outer membrane; cyan, mitochondrial IBM; purple red and yellow, lamellar crista without CJ. H Quantification of the “cut-through crista” in mitochondria of control and Mic10 KO HeLa cells. “others” means “other types of crista except for cut-through crista” (n = 100 cristae). Statistical significance was assessed from the student’s t-test; error bars indicate the means ± SD of three independent experiments, ***p < 0.001 versus control. I Mitochondria in COS-7 cells were stained with 250 nM MitoTracker Green for 15 min, then were tracked and imaged by time-lapse Hessian-SIM. The green arrowhead indicates the contact and fusion site of two different mitochondria, the red arrowhead indicates the newly formed crista. J Live OPA1 KO MEFs were stained with MitoTracker Green (250 nM, 15 min) and imaged by Hessian-SIM. The representative mitochondrial cristae were displayed. The green arrowhead indicates “cut-through crista”, the red arrowhead indicates “lamellar crista”.