Cell-autonomous survival of Purkinje neurons. A, Sagittal, midline sections of the cerebellum were stained with anti-D28K to mark remaining PNs and anti-GFP to locate NPC1-YFP expression. At age P65, in a G; N; Npc1−/− mouse, patterned loss of PNs (loss of D28K stain from lobules) can be seen. At age P80, significant loss of PNs is noticeable. At age P90, in a P; N; Npc1−/− mouse, PNs remain and NPC1-YFP is localized to the PN layer (boxed region and zoomed in inset). Note that lobule X was used as a landmark for section comparison since PNs in lobule X are unaffected. B, Representative immunoblot comparing the levels of D28K and MBP in whole cerebellum samples from P; N; Npc1−/− and G; N; Npc1−/− mice to Npc1+/− and Npc1−/− mice. MBP isoforms at 21.5, 18, and 17 kDa are shown. Notice the much larger amount of NPC1-YFP produced in a G; N; Npc1−/− mouse cerebellum compared to an age-matched P; N; Npc1−/− mouse; despite this, there is no obvious rescue of MBP and D28K level in a G; N; Npc1−/− mouse sample, but there is in a P; N; Npc1−/− mouse sample.