Danks GB, Raasholm M, Campsteijn C, Long AM, Manak JR, Lenhard B, Thompson EM.

Mol Biol Evol. 2015 Mar;32(3):585-99. doi:10.1093/molbev/msu336

Trans-Splicing and Operons in Metazoans: Translational Control in Maternally Regulated Development and Recovery from Growth Arrest.

“39% of annotated gene models are trans-spliced with the SL.” “42% of SL transcripts are monocistronic; in these cases SL trans-splicing has a function other than resolving polycistronic mRNA.” “A second wave of gene activation peaked at the metamorphic tailshift stage where 2,578 genes were switched on for the first time. Here, 80% of genes were non-trans-spliced nonoperon genes, only 4% were SL-trans-spliced operon genes, and 10% were SL-trans-spliced monocistronic genes.” “A Switch from Predominantly Trans-Spliced to Predominantly Non-trans-Spliced Transcripts Occurs at the Maternal to Zygotic Transition” Parallel study in O. dioica, C. elegans and C. intestinalis suggests that “trans-splicing itself, rather than the organization of genes into operons, is the common factor for maternal mRNA in these metazoans”. The TOP motif of ribosomal protein genes is provided by the SL in O. dioica. “We find that SL-trans-spliced mRNAs are enriched in the ovary and oocytes.”