Fig. 9. Mitochondria restricted to the cell body are sufficient to induce synaptic degeneration. (A-L) Cross sections of the lamina neuropil in wild-type (A,E,I), SdhA¹¹¹⁰ mutant (B,F,J), Miro (C,G,K) and SdhA¹¹¹⁰; Miro double mutant eye-specific mosaic (D,H,L) animals, at 0 days after eclosion (A-D) or 5 days after eclosion (E-L). R cells (green) and CSP (magenta). (I-L) Single channel images stained for vesicles of 5-day laminas. (M) Schematic describing the logic of this experiment. Mitochondria are normally found in both cell bodies and axons. Thus, in SdhA mutants, excess ROS could be produced in both compartments. However, transport of mitochondria from cell bodies to axons is dependent upon Miro. To test whether synapse loss was induced by ROS locally in the terminal, we blocked axonal transport of SdhA mutant mitochondria using mutations in Miro, thereby restricting ROS production to the cell body. Retinas in control flies were made homozygous for two FRT chromosomes using two cell-lethal mutations. SdhA and Miro single homozygote retinas were also heterozygous for Miro and SdhA, respectively. Scale bar: 20 µm.