Figure 7.
Null dnpc1a mutant neuron clones display cell-autonomous requirements in cholesterol trafficking and neuronal maintenance. A, Central brain labeled with MARCM UAS-CD8-GFP driven by elav-GAL4 and filipin staining for sterol aggregates. Top panels show wild-type control MARCM whole-brain clones, whereas bottom panels show randomly generated dnpc1a null mutant clones. Null dnpc1a clones are green fluorescent protein (GFP) positive (bottom left, white arrows) and colocalize with cholesterol-rich, filipin-positive aggregates (bottom right, white arrows). Whole-brain MARCM control neurons are all GFP positive (top left) and display a diffuse low level of filipin staining with no puncta (top right). All brains are aged to 30 d posteclosion. B, Panels show ultrathin (50–60 nm) electron microscopy sections of elav-GAL4 MARCM brains in control (left) and dnpc1 null (right). MARCM dnpc1a mutant clones accumulate numerous MLBs (black arrows) in neuronal cell soma, whereas adjacent cells show normal ultrastructure. MARCM controls display no MLBs in neuronal soma. All brains are aged to 30 d posteclosion. Scale bars: A, 50 μm.; B, 2 μm.