FIGURE 4.

Trans- and alternative trans-splicing of mod(mdg4) in the silkworm. (A) Trans-spliced forms of mod(mdg4) in B. mori encode a common BTB domain at the N terminus from exon1 to exon4 of BGIBMGA006426 and variable FLYWCH domains at the C terminus from eight genes on the opposite DNA strand in the same scaffold (nscaf2853). RT-PCR analysis and sequencing confirmed all nine trans-splicing events with precise splice sites. (B) mRNA profiles of the nine opposite-strand trans-splicing events in different developmental stages and tissues. RT-PCR analysis from different B. mori samples indicated that some trans-splicing events were specific to one or several stages or tissues. Alternative trans-splicing was observed for one of the 3′-exon genes, BGIBMGA006451, which can be trans-spliced into two isoforms of mod(mdg4) to produce trans-P51.1 and P51.2.