Experimentally verified introns in mlncRNA transcripts. The expression of the spliced transcript was tested in embryo (E), larva (L), pupa (P), male (♂), and female (♀) stages. Ethidium bromide–stained agarose gels show the RT-PCR results for D. melanogaster. Expression data of the orthologous transcripts in D. simulans (D.sim), D. erecta (D.ere), and D. pseudoobscura (D.pse) are shown below the D. melanogaster (D.mel) data. Genomic DNA (gen.) was used as a PCR control, and size was measured according to a 100-bp Ladder (M). PCR products were verified by sequencing. +/++, expressed; −, no band; n.o., no orthologous intron; n.t., not tested. Weaker and stronger expression in different stages are indicated by + and ++, respectively.