Increased accumulation of enlarged Rab5-associated endosomes in ALS2-/- hippocampal neurons. A-B. Representative images of wild-type (WT; A) and ALS2-/- (KO; B) hippocampal neurons transfected with GFP-Rab5 (a, green) and counterstained with an antibody against MAP2 (b, red). Fragments of soma (inset), axon (middle panel) and dendrite (bottom panel) were enlarged to reveal the distribution and morphology of Rab5-positive vesicles. Panel 'c' is an overlay. Scale bar: 20 μm (main) and 5 μm (inset, middle and bottom panels). C. Histogram reveals the distribution of Rab5-associated vesicles within each size category in WT and KO neurons (n = 5). D. Histogram reveals the average size of Rab5-associated vesicles (n > 45) in wild-type (WT (Rab5)), ALS2-/- (KO (Rab5)), ALS2-transfected ALS2-/- (KO (Rab5+ALS2)) and DsRed-transfecetd ALS2-/- (KO (Rab5+vector)) neurons. Error bars represent SEM. *** P < 0.001.