Figure 6.

Electron microscopy of changes in ER and mitochondrial distribution and morphology in DLP1-defective cells. Selected transmission electron microscopic images from control uninjected cells, cells fixed for 16–24 h after nuclear injection with GFP-DLP1-K38A, or cells injected with inhibitory DLP1 antibodies. In control cells, the cytoplasm is filled with long strands of interconnected rough ER (A, arrows) interspersed with mitochondria of uniform size (A, arrowheads). A higher magnification resolves the normal morphology of these prevalent organelles (B, arrows and arrowheads). In contrast, cells injected with GFP-DLP1-K38A (C and D) or inhibitory DLP1 antibodies (E and F) show mitochondria collapsed to a perinuclear region (C and E, arrowheads). These cells possessed shortened, ill-defined ER profiles close to the nuclear envelope (C and E, arrows) and large cytoplasmic expanses completely devoid of ER (compare A, C, and E). At higher magnification, the ER cisternae appear less defined and in close proximity to mitochondria, and the mitochondria appear swollen, elongated, and branched with highly resolved cristae (D and F, arrowheads). Bars, 1 μm.