Ablation of Sam68 rescues SMN assembly into nuclear gems in spinal cord motor neurons. (A) Immunodetection of SAM68 (blue) in ChAT-positive motor neurons (red) in the lumbar spinal cord (L1–L5) of 8-dpp non-SMA mice. DAPI was used for staining of nuclei. Motor neurons are indicated by arrows and surrounding cells by arrowheads. (B) Immunodetection of SMN gems (green) in ChAT-positive motor neurons (red) in the spinal cord (L1–L5) of 8-dpp non-SMA, SMAΔ7/Sam68^+/+, and SMAΔ7/Sam68^−/− (SMA) mice. DAPI was used for staining of nuclei. Nuclear gems are indicated by arrowheads. Bars: (A and B) 20 µm; (insets) 10 µm. (C) Quantitative analysis of SMN gems in spinal motor neurons. The bar graph (mean ± SD; n = 3) shows the number of gems per 100 nuclei analyzed per sample (top) and the percentage of gem-positive motor neurons (bottom). Statistical analysis was performed by one-way ANOVA test followed by Bonferroni’s multiple comparison posttest (*, P < 0.05; ***, P < 0.001).