Fig. 7: Ultrastructure analysis of ER morphology.

a Correlated light and electron microscopy of shCLIMP-63 HeLa cells overexpressing RFP-CLIMP-63 WT, CC or C100S, or RFP-CLIMP-63 WT together with ZDHHC6-myc. Light microscopy images (top) with the boxed region (red) indicating the area imaged with TEM (middle) and zoomed region (bottom) (second red box). Scale bars: 1 μm. b FIBSEM was used to 3D image the ER in RFP-CLIMP-63 in control or upon overexpression of ZDHHC6 (detected by the presence of OSERs—yellow arrowheads). FIBSEM image stacks depict the convoluted branching pattern of the ER. Numerous closed loops of ER membrane can be seen in the two imaging planes upon ZDHHC6-myc expression (red arrows). Reconstruction of ER (green) with the reconstructed mitochondria (pink). Scale bars: 1 μm. c Quantification of ER-membrane loops by degree-1 persistent homology and d ER cavities by degree-2 persistent homology in control and ZDHHC6-myc overexpression.