title: Genomic overview of mRNA 5'-leader trans-splicing in the ascidian Ciona intestinalis.
abstract: Although spliced leader (SL) trans-splicing in the chordates was discovered in the tunicate Ciona intestinalis there has been no genomic overview analysis of the extent of trans-splicing or the make-up of the trans-spliced and non-trans-spliced gene populations of this model organism. Here we report such an analysis for Ciona based on the oligo-capping full-length cDNA approach. We randomly sampled 2078 5'-full-length ESTs representing 668 genes, or 4.2% of the entire genome. Our results indicate that Ciona contains a single major SL, which is efficiently trans-spliced to mRNAs transcribed from a specific set of genes representing approximately 50% of the total number of expressed genes, and that individual trans-spliced mRNA species are, on average, 2-3-fold less abundant than non-trans-spliced mRNA species. Our results also identify a relationship between trans-splicing status and gene functional classification; ribosomal protein genes fall predominantly into the non-trans-spliced category. In addition, our data provide the first evidence for the occurrence of polycistronic transcription in Ciona. An interesting feature of the Ciona polycistronic transcription units is that the great majority entirely lack intercistronic sequences.
authors.affiliation: Department of Zoology, Graduate School of Science, Kyoto University Sakyo, Kyoto 606-8502, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Satou
authors.forename: Makoto
authors.initials: M
authors.lastname: Hamaguchi
authors.forename: Keisuke
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Kenneth E M
authors.initials: KE
authors.lastname: Hastings
authors.forename: Nori
authors.initials: N
authors.lastname: Satoh
mesh_terms: D000818:Animals; D001483:Base Sequence; D002938:Ciona intestinalis / Q000235:genetics* / Q000378:metabolism; D020224:Expressed Sequence Tags; D015723:Gene Library; D023281:Genomics; D008969:Molecular Sequence Data; D009876:Operon; D012333:RNA, Messenger / Q000378:metabolism; D020038:RNA, Spliced Leader / Q000737:chemistry / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics; D020040:Trans-Splicing; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D020038:RNA, Spliced Leader; D012269:Ribosomal Proteins