FIGURE 2.

Identification of alternative splicing events in B. mori. The alternative splicing events in the silkworm are classified as (A) skipped exons, (B) retained introns, (C) alternative 5′SS, (D) alternative 3′SS, or (E) mutually exclusive exons. The numbers of each type of event are indicated, and there were 1923 events in total. (F) As a subtype of alternative 3′SS, events of tandem 3′ splice site separated by 3 nt were specifically analyzed. Supporting RNA-seq reads and RT-PCR amplifications are shown for randomly selected events from each type. The positions of all primers used for PCR are indicated, and the amplified products were confirmed by sequencing. Specifically for the case of tandem 3′SS in panel F, the two alternative splicing products are 3 nt different in length, and were detected as 2:2 after sequencing of four clones. This is reasonable with the abundance of RNA-seq reads that support the prediction of the two isoforms, which was 105 to 59.