Atypical RNAs in the coelacanth transcriptome
Circular and apparently trans-spliced RNAs have recently been reported as abundant types of transcripts in mammalian transcriptome data. Both types of non-colinear RNAs are also abundant in RNA-seq of different tissue from both the African and the Indonesian coelacanth. We observe more than 8,000 lincRNAs with normal gene structure and several thousands of circularized and trans-spliced products, showing that such atypical RNAs form a substantial contribution to the transcriptome. Surprisingly, the majority of the circularizing and trans-connecting splice junctions are unique to atypical forms, that is, are not used in normal isoforms.