Figure 8
SmVAL6 exhibits developmentally-regulated alternative splicing . Sixty-seven individual SmVAL6 cDNA clones (spanning exons 4–38) were isolated and sequenced from parasite material: 32 clones were derived from 7-week mixed-sex adult worm cDNA and 35 clones from mixed-sex cercarial cDNA (see Methods). A) Thirty-five distinct SmVAL6 isoforms were identified from the sixty-seven clones sequenced. Columns represent exon number (as described in Fig. 5) and rows indicate the 35 detected isoforms. Filled, grey boxes represent presence of exon, whereas empty, white boxes represent absence of exon in each of the 35 isoforms. The presence of an asterisk indicates an exon encoding a premature stop codon. The diagonal lines in the exon 35 column indicate that this exon has been detected in previous studies but was not observed in any of the transcripts in this experiment. B) Presence of exons 20 and 26 is associated with adult cDNA clones. Frequency of exon 20 and 26 usage in adult (black bars) and cercariae clones (grey bars) is shown with the χ2 test p values indicated. The amino acids encoded by each exon are shown below, with amino acids spanning splice acceptor/donator sites indicated in parentheses.