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Splice Leaders in Bdelloids

Analysis of full-length cDNA libraries from bdelloid rotifers A. ricciae and Philodina sp. revealed a number of cDNAs with a common 23-nt sequence at their 5' ends.

The same DNA segment was found on cDNAs encoding a variety of proteins including structural proteins, metabolic enzymes and regulatory proteins in both bdelloid species. This is diagnostic of spliced leader (SL) RNA-mediated trans-splicing, whereby 5' ends of precursor mRNAs are replaced by a short exon from a small SL RNA (Fig. 1).

The description of SL-mediated trans-splicing in Rotifera extends its representation to at least five metazoan taxa, the others being nematodes, cnidarians, platyhelminths and primitive chordates, making it increasingly probable that this is a phylogenetically widespread and therefore ancient phenomenon.

Rotifer splice leader
Fig.1: Bdelloid spliced leader RNA, which donates the SL exon to mRNA precursors by trans-splicing


Bdelloid Rotifer Research Topics:


Pouchkina-Stantcheva, N. N. and Tunnacliffe, A. (2005) Spliced-leader RNA mediated trans-splicing in phylum Rotifera. Mol. Biol. Evol22: 1482-1489.