Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Comparative Validation of the D. melanogaster Encyclopedia of DNA Elements Transcript Models

ABSTRACT: The model organism Encyclopedia of DNA Elements project (modENCODE) has produced a comprehensive annotation of D. melanogaster transcript models based on an enormous amount of high-throughput experimental data. However, some transcribed elements may not be functional, and technical artifacts may lead to erroneous inference of transcription. Inter-species comparison provides confidence to predicted annotation, since transcriptional activity that has been evolutionarily conserved is likely to have an advantageous function. We have performed RNA-Seq and CAGE-Seq experiments on more than 80 samples from multiple tissues and stages of 15 Drosophila species, including 8 previously unsequenced genomes. We have found strikingly conserved sequence, expression, and splicing for the vast majority of transcript models in modENCODE annotation (e.g. 99% exons of coding sequences (CDS), 88% exons of untranslated regions (UTR), and 87% splicing events), indicating that the transcriptome annotation is of very high quality. We also describe dynamic transcriptome evolution within the Drosophila genus, including conserved promoter structure, labile positions of transcription start sites, and rapidly evolving RNA-editing events. We demonstrate how this phylogenetic approach to DNA element validation will prove useful in the annotation of other high priority genomes, especially for genomes that are less compact than Drosophila (e.g. the vast majority of vertebrate genomes). Refer to individual Series (listed below).

ORGANISM(S): Drosophila ficusphila

SUBMITTER: Brian Oliver

PROVIDER: E-GEOD-44612 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3b signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters.Upon withdrawal of 2i/LIF, naM-CM-/ve mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalency acquisition on lineage regulatory genes. The feasibility for establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in rodent ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation of cross-species chimaeric embryos that underwent organogenesis following microinjection of human naive iPS cells into mouse morulas. Collectively, our findings establish new avenues for regenerative medicine, patient-specific iPS cell disease modelling and the study of early human development in vitro and in vivo. Four chromatin marks H3K4me1, H3K4me3, H3K27ac and H3K27me3 were measured from 3 cell lines: C1 and WIBR3 (naM-CM-/ve and conventional/primed stem cells), and BGO1 (only naM-CM-/ve stem cells).

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Comparative Validation of the D. melanogaster Encyclopedia of DNA Elements Transcript Models

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