Fig. 4.

AIBP deficiency induces mitochondrial fragmentation, outer membrane onion-like swirls, lower crista density, and reduces ATP production in Müller glia endfeet. (A) SBEM WT volume showing typical cytoplasmic structures; mitochondria (yellow trace) highlighted. (B) SBEM Apoa1bp^−/− volume showing mitochondria (yellow trace) with lower crista density (red arrowheads) and dark outer membrane onion-like swirls (blue trace). (C) WT surface rendering (Volume: 4830 μm³ 30μmx23 μmx7μm; voxel size: 3nm × 3nm × 50nm) highlighting long tubular mitochondria (yellow) (cytoplasmic membrane--blue). (D) Surface rendering (Volume: 4408 μm³, 29μmx19 μmx8μm; voxel size 3nm × 3nm × 50nm) showing short fragmented mitochondria (yellow) in Apoa1bp^−/−. (E-G) Expedited and accurate segmentation and analysis of mitochondria. (E-F) Cross image planes (a–d) showing the need for 3DEM. 357 electron micrographs (50-nm step) were serially collected to follow many mitochondria through the large volume. (G) Approach to determine mitochondrial length (red) and variable shapes. (H) Surface rendering showing long tubular forms of mitochondria in WT. (I) Surface rendering showing smaller, round forms of mitochondria in Apoa1bp^−/−. (J) The volume of mitochondria was not significantly different in the Apoa1bp^−/−. (K) The mitochondrial volume density in the Apoa1bp^−/− was almost identical to the WT. (L) No significant difference in the number of mitochondria between WT and Apoa1bp^−/−. (M) The form factor for Apoa1bp^−/− mitochondria was significantly lower, confirming less elongation. (N) The mitochondrial length was significantly lower in the Apoa1bp^−/−. (O) The crista density was significantly lower in the Apoa1bp^−/−. (P) The rate of ATP production per mitochondrial volume was lower in the Apoa1bp^−/−. (Q) The modeled rate of ATP production per mitochondrion was no different in the Apoa1bp^−/−. (R) There was a significant lowering of ATP availability per unit cellular volume in the Apoa1bp^−/−. N = 3 Müller glia from 2 mice per group. Scale bars: 1 μm (A and B), 50 nm (C–I). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)