(A) Mitochondrial motility in dendrites of neurons transfected with Miro-Myc (left panels), or MiroKK-Myc (right panels), together with PSD95-YFP (to mark dendrites), and RFP-mito. Kymographs of RFP-mito were made before (upper) and after (lower) a 1 min exposure to glutamate. (B) From kymographs as in A, the percent of time mitochondria were in motion was determined and averaged (n=53-61 mitochondria from 6 axons and 3 separate transfections). Glutamate (Glu) arrested bidirectional mitochondrial movement in Miro-transfected, but not MiroKK-transfected dendrites. (C) Representative 25× magnification views of neurons transfected with GFP and Miro (left two panels), or GFP and MiroKK (right two panels). After incubation with 10μM NMDA for 5 min, the neurons were either imaged directly (acute) or cultured for 24 h and then imaged. Scale bars, 100 μm. (D) Quantification of surviving neurons. NMDA (0 to 30 μM) was incubated with the transfected neurons for 5 min, and GFP positive neurons were counted 24 h later under 25× along one diameter of the coverslip. Each data point was from 10 coverslips from 3 separate transfections. Significantly different pairs are marked. (E) Schematic model of the means by which Ca++ interacts with Miro to regulate the anterograde motility of mitochondria.