SL RNA genes of the ascidian tunicates Ciona intestinalis and Ciona savignyi.
We characterized by bioinformatics the trans-spliced leader donor RNA (SL RNA) genes of two ascidians, Ciona intestinalis and Ciona savignyi. The Ciona intestinalis genome contains approximately 670 copies of the SL RNA gene, principally on a 264-bp tandemly repeated element. Fluorescent in-situ hybridization mapped most of the repeats to a single site on the short arm of chromosome 8. The Ciona intestinalis genome also contains approximately 100 copies of a >3.6-kb element that carries 1) an SL RNA-related sequence (possible a pseudogene) and 2) genes for the U6 snRNA and a histone-like protein. The Ciona savignyi genome contains two SL RNA gene classes having the same SL sequence as Ciona intestinalis but differing in the intron-like segments. These reside in similar but distinct repeat units of 575 bp ( approximately 410 copies) and 552 bp ( approximately 250 copies) that are arranged as separate tandem repeats. In neither Ciona species is the 5S RNA gene present within the SL RNA gene repeat unit. Although the number of SL RNA genes is similar, there is little sequence similarity between the intestinalis and savignyi repeat units, apart from the region encoding the SL RNA itself. This suggests that cis-regulatory elements involved in transcription and 3'-end processing are likely to be present within the transcribed region. The genomes of both Ciona species also include > 100 dispersed short elements containing the 16-nt SL sequence and up to 6 additional nucleotides of the SL RNA sequence.
Montreal Neurological Institute and Department of Biology, McGill University, 3801 University Street, Montréal, Québec, Canada H3A 2B4.
Brendan
B
Yeats
Jun
J
Matsumoto
Sandra I
SI
Mortimer
Eiichi
E
Shoguchi
Nori
N
Satoh
Kenneth E M
KE
Hastings
D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D016678:Genome; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D020038:RNA, Spliced Leader / Q000235:genetics*; D014561:Urochordata / Q000235:genetics*
D020038:RNA, Spliced Leader