Fig. 4

Expression of alternatively spliced transcripts in mbnl2 morphants. (A) RT-PCR analysis using primers tnnt2F and tnnt2R3 (arrows) yields two main bands of 318 bp and 282 bp in control embryos (‘C’), whereas the 282 bp product is not detectable in the morphants (MO). Boxes depict the exon content of each product after sequencing. Exons 4 (green) and 6 (yellow) are alternatively spliced. (B) The normal tnnt2 alternative splicing pattern is shown at different developmental stages. RT-PCR analysis of control embryos at the 18-somite stage (1) and 24 hpf (2) shows the expression of a 318 bp product. 51 hpf (3), 76 hpf (4) and adult (5) controls express both isoforms, 318 bp and 282 bp. (C) RT-PCR analysis of clcn1. Primers clcn1-134F and clcn1-87R (arrows) produce two bands, one of 588 bp (including exon 18a) and one of 555 bp (excluding exon 18a), which are expressed at a ratio of 1:1.2 in control embryos, whereas, in the mbnl2 morphants, the 555 bp product is the predominant form, shifting the ratio to 1:1.98. Differences in exon content are shown in the boxes. Exon 18a (red) is alternatively spliced and encodes amino acids FTKLSPAGGVK.