Spliced-leader trans-splicing in freshwater planarians

Ricardo M. Zayas, Tyler D. Bold, Phillip A. Newmark

    Research output: Contribution to journalArticlepeer-review


    trans-Splicing, in which a spliced-leader (SL) RNA is appended to the most 5′ exon of independently transcribed pre-mRNAs, has been described in a wide range of eukaryotes, from protozoans to chordates. Here we describe trans-splicing in the freshwater planarian Schmidtea mediterranea, a free-living member of the phylum Platyhelminthes. Analysis of an expressed sequence tag (EST) collection from this organism showed that over 300 transcripts shared one of two ∼35-base sequences (Smed SL-1 and SL-2) at their 5′ ends. Examination of genomic sequences encoding representatives of these transcripts revealed that these shared sequences were transcribed elsewhere in the genome. RNA blot analysis, 5′ and 3′ rapid amplification of cDNA ends, as well as genomic sequence data showed that 42-nt SL sequences were derived from small RNAs of ∼110 nt. Similar sequences were also found at the 5′ ends of ESTs from the planarian Dugesia japonica. trans-Splicing has already been described in numerous representatives of the phylum Platyhelminthes (trematodes, cestodes, and polyclads); its presence in two representatives of the triclads supports the hypothesis that this mode of RNA processing is ancestral within this group. The upcoming complete genome sequence of S. mediterranea, combined with this animal's experimental accessibility and susceptibility to RNAi, provide another model organism in which to study the function of the still-enigmatic trans-splicing.

    Original languageEnglish (US)
    Pages (from-to)2048-2054
    Number of pages7
    JournalMolecular biology and evolution
    Issue number10
    StatePublished - Oct 2005


    • Dugesia japonica
    • Planarian
    • Platyhelminthes
    • Schmidtea mediterranea
    • Spliced-leader RNA
    • trans-splicing

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics
    • Molecular Biology
    • Genetics


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