title: RNA sequencing reveals a diverse and dynamic repertoire of the Xenopus tropicalis transcriptome over development.
abstract: The Xenopus embryo has provided key insights into fate specification, the cell cycle, and other fundamental developmental and cellular processes, yet a comprehensive understanding of its transcriptome is lacking. Here, we used paired end RNA sequencing (RNA-seq) to explore the transcriptome of Xenopus tropicalis in 23 distinct developmental stages. We determined expression levels of all genes annotated in RefSeq and Ensembl and showed for the first time on a genome-wide scale that, despite a general state of transcriptional silence in the earliest stages of development, approximately 150 genes are transcribed prior to the midblastula transition. In addition, our splicing analysis uncovered more than 10,000 novel splice junctions at each stage and revealed that many known genes have additional unannotated isoforms. Furthermore, we used Cufflinks to reconstruct transcripts from our RNA-seq data and found that ∼13.5% of the final contigs are derived from novel transcribed regions, both within introns and in intergenic regions. We then developed a filtering pipeline to separate protein-coding transcripts from noncoding RNAs and identified a confident set of 6686 noncoding transcripts in 3859 genomic loci. Since the current reference genome, XenTro3, consists of hundreds of scaffolds instead of full chromosomes, we also performed de novo reconstruction of the transcriptome using Trinity and uncovered hundreds of transcripts that are missing from the genome. Collectively, our data will not only aid in completing the assembly of the Xenopus tropicalis genome but will also serve as a valuable resource for gene discovery and for unraveling the fundamental mechanisms of vertebrate embryogenesis.
authors.affiliation: Department of Genetics, Stanford University School of Medicine, Stanford, California 94305, USA. menghow.tan@gmail.com
authors.forename: Meng How
authors.initials: MH
authors.lastname: Tan
authors.forename: Kin Fai
authors.initials: KF
authors.lastname: Au
authors.forename: Arielle L
authors.initials: AL
authors.lastname: Yablonovitch
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Wills
authors.forename: Jason
authors.initials: J
authors.lastname: Chuang
authors.forename: Julie C
authors.initials: JC
authors.lastname: Baker
authors.forename: Wing Hung
authors.initials: WH
authors.lastname: Wong
authors.forename: Jin Billy
authors.initials: JB
authors.lastname: Li
mesh_terms: D000818:Animals; D004474:Ecthyma, Contagious; D004625:Embryo, Nonmammalian / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007438:Introns; D007814:Larva / Q000235:genetics / Q000378:metabolism; D020161:Physical Chromosome Mapping; D012326:RNA Splicing; D022661:RNA, Untranslated; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA; D059467:Transcriptome; D014981:Xenopus / Q000235:genetics* / Q000254:growth & development
chemical_list: D022661:RNA, Untranslated