(A) Analysis of rRNA synthesis. Total RNA was extracted from spinal muscular atrophy (SMA) and control embryonic motor neurons. The levels of 45S pre-rRNA along with 18S, 5.8S, and 28S mature rRNAs were determined by quantitative reverse transcription PCR (qRT-PCR) and normalised to GAPDH levels. Data are presented as mean ± SEM (N = 3). *P < 0.05, **P < 0.01 paired two-tailed t test; P = 0.1512 (45S), P = 0.0284 (18S), P = 0.007 (5.8S), P = 0.4612 (28S). (B) Total RNA was extracted from SMA and control embryonic cortical neurons. The levels of 45S pre-rRNA along with 18S, 5.8S, and 28S mature rRNAs were determined by qRT-PCR and normalised to GAPDH levels. Data are presented as mean ± SEM. (N = 3). Paired two-tailed t test; P = 0.2148 (45S), P = 0.9570 (18S), P = 0.5376 (5.8S), P = 0.8083 (28S). (C) SMA and control embryonic motor neurons were stained to reveal overall morphology (beta-III-tubulin, magenta) and nuclear integrity (Hoechst, blue). Protein synthesis was visualized by labelling newly synthesized proteins with L-azidohomoalanine (AHA, green). SMA motor neurons were transduced with Ad-hSETX or lentiviral vector survival motor neuron (SMN) FL before staining. Scale bars represent 10 μm. (D) AHA fluorescence intensity values normalised to control samples. Bar graphs of mean ± SEM #P < 0.05 (comparing SMA cells treated with lentiviral vector-SMN and SMN untreated cells), ##P < 0.01 (comparing SMA cells treated with Ad-SETX and SMA untreated cells) and **P < 0.01 (comparing SMA and control untreated cells). One-way ANOVA analysis followed by Tukey’s multiple comparisons test; F (1.615, 3.229) = 13.79. P = 0.0273. The data were collected from N = 3 and were normally distributed.