The sequence of the splice donor site is not a key determinant of minor intron retention in spinal cords of SMA mice. RT-PCR analysis of minor introns splicing in spinal cords of control (WT6, WT7) and SMA (KO6, KO9, KO10) mice. (A) Unaffected minor introns containing canonical 5′ splice site sequences. (B) Retained minor introns containing canonical 5′ splice site sequences. (C) Unaffected minor introns containing suboptimal 5′ splice site sequences. Nucleotides diverging from the consensus are underlined. (D) Retained minor introns containing suboptimal 5′ splice site sequences. Nucleotides diverging from the consensus are underlined. Gene names and size (in base pairs) of the amplified products are indicated on the left. The schematic structure of the amplified products is shown on the right. (E) Retention index of minor introns in spinal cords of control (WT, n = 2) and SMA (SMA, n = 3) mice determined as described in the Materials and Methods section. Mean and SEM are shown. Statistical significance was calculated using the Student t-test (ns: nonsignificant; (*) P < 0.05; (**) P < 0.01; (***) P < 0.005). Histograms for Mapk1 and Ncbp2 are not shown because retained introns are not or hardly detectable.
