Identification of novel exons and transcribed regions by chimpanzee transcriptome sequencing.
BACKGROUND
We profile the chimpanzee transcriptome by using deep sequencing of cDNA from brain and liver, aiming to quantify expression of known genes and to identify novel transcribed regions.


RESULTS
Using stringent criteria for transcription, we identify 12,843 expressed genes, with a majority being found in both tissues. We further identify 9,826 novel transcribed regions that are not overlapping with annotated exons, mRNAs or ESTs. Over 80% of the novel transcribed regions map within or in the vicinity of known genes, and by combining sequencing data with de novo splice predictions we predict several of the novel transcribed regions to be new exons or 3' UTRs. For approximately 350 novel transcribed regions, the corresponding DNA sequence is absent in the human reference genome. The presence of novel transcribed regions in five genes and in one intergenic region is further validated with RT-PCR. Finally, we describe and experimentally validate a putative novel multi-exon gene that belongs to the ATP-cassette transporter gene family. This gene does not appear to be functional in human since one exon is absent from the human genome. In addition to novel exons and UTRs, novel transcribed regions may also stem from different types of noncoding transcripts. We note that expressed repeats and introns from unspliced mRNAs are especially common in our data.


CONCLUSIONS
Our results extend the chimpanzee gene catalogue with a large number of novel exons and 3' UTRs and thus support the view that mammalian gene annotations are not yet complete.
Wetterbom
Anna
A
Department of Genetics and Pathology, Rudbeck laboratory, Uppsala University, SE-751 85 Uppsala, Sweden.
Ameur
Adam
A
Feuk
Lars
L
Gyllensten
Ulf
U
Cavelier
Lucia
L
D000818:Animals; D002540:Cerebral Cortex / Q000378:metabolism; D021901:DNA, Intergenic / Q000235:genetics; D005091:Exons / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015894:Genome, Human / Q000235:genetics; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D009928:Organ Specificity / Q000235:genetics; D002679:Pan troglodytes / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA / Q000379:methods*; D012727:Sex Characteristics; D014158:Transcription, Genetic; D020506:Untranslated Regions / Q000235:genetics
D021901:DNA, Intergenic; D012333:RNA, Messenger; D020506:Untranslated Regions