Figure 6.

Effects of dnDrp1 expression on neurogenesis under basal conditions and in the context of voluntary exercise. A, Under basal conditions, control transduced 8 dpi neurons show polarized morphology and start to grow a primary dendrite toward the molecular cell layer (white arrow). dnDrp1-expressing cells (red arrowhead) showed stunted morphology and limited mitochondrial content (in green). Cells in the same animal, which were transduced only with the control RFP-encoding retrovirus (white arrowhead), grow a primary dendrite toward the molecular cell layer. Scale bar, 15 μm. B, Comparison of the ratio between all mitoGFP-positive cells (green + yellow) to RFP-only cells (red) under nonrunning conditions. Note that the ratio decreases between 8 and 16 dpi in dnDrp1 retrovirus-injected animals. C, Running conditions: control-transduced 16 dpi neurons express the immature neuronal marker DCX (in blue; white arrow). dnDrp1-expressing cells frequently fail to express DCX and extend processes parallel to the subgranular zone (red arrowhead). Note the long tubular mitochondrial morphology. dnDrp1-expressing cells, which are positive for DCX, only grow short dendrites toward the molecular cell layer (white arrowhead). Note that mitochondria are confined to the soma. Scale bar, 15 μm. D, Quantification of transduced cells expressing DCX at 16 dpi under running conditions. E, Quantification of transduced cells bearing a primary dendrite spanning the granule cell layer at 16 dpi under running conditions. Error bars represent the SEM.