FIGURE 4.

A, targeting the endogenous UTE generates α2Δ9A mRNA, a potential non-stop decay substrate. Endogenous α7, α2, and 05 RNAs were analyzed by RT-PCR using a ³²P-labeled sense primer specific for exon 8 and reverse primers specific for exon 9′, 9B, and 9D, respectively. The PCR products were quantified by PhosphorImager analysis and normalized to EF1-α. The bar diagram shows the log₂ mean -fold change ± S.D. of the different α-tropomyosin isoforms in morpholino-injected embryos relative to uninjected embryos (n = 3 independent experiments). B, reduction of the α2Δ9A mRNA is translation-dependent. A morpholino complementary to the region encompassing the start codon of the muscle α-tropomyosin mRNAs (TM Mo) was injected alone or in combination with UTE-1 Mo. The steady-state level of muscle α-tropomyosin was studied by Western blot with the monoclonal anti-tropomyosin antibody (clone TM311). Non-muscle tropomyosin was used as a loading control. Endogenous α2 and α2Δ9A RNAs were analyzed by RT-PCR using primers specific for exon 7 and 9B. The PCR products were quantified by PhosphorImager analysis and normalized to EF1-α. Data were presented as mean -fold change ± S.D. of α2Δ9A RNA in morpholino-injected embryos relative to uninjected embryos (n = 3 independent experiments).