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1.  Genomic and Phenotypic Characterization of a Wild Medaka Population: Towards the Establishment of an Isogenic Population Genetic Resource in Fish 
G3: Genes|Genomes|Genetics  2014;4(3):433-445.
Oryzias latipes (medaka) has been established as a vertebrate genetic model for more than a century and recently has been rediscovered outside its native Japan. The power of new sequencing methods now makes it possible to reinvigorate medaka genetics, in particular by establishing a near-isogenic panel derived from a single wild population. Here we characterize the genomes of wild medaka catches obtained from a single Southern Japanese population in Kiyosu as a precursor for the establishment of a near-isogenic panel of wild lines. The population is free of significant detrimental population structure and has advantageous linkage disequilibrium properties suitable for the establishment of the proposed panel. Analysis of morphometric traits in five representative inbred strains suggests phenotypic mapping will be feasible in the panel. In addition, high-throughput genome sequencing of these medaka strains confirms their evolutionary relationships on lines of geographic separation and provides further evidence that there has been little significant interbreeding between the Southern and Northern medaka population since the Southern/Northern population split. The sequence data suggest that the Southern Japanese medaka existed as a larger older population that went through a relatively recent bottleneck approximately 10,000 years ago. In addition, we detect patterns of recent positive selection in the Southern population. These data indicate that the genetic structure of the Kiyosu medaka samples is suitable for the establishment of a vertebrate near-isogenic panel and therefore inbreeding of 200 lines based on this population has commenced. Progress of this project can be tracked at http://www.ebi.ac.uk/birney-srv/medaka-ref-panel.
doi:10.1534/g3.113.008722
PMCID: PMC3962483  PMID: 24408034
Medaka; inbreeding; population genomics; strain specific features
2.  Ensembl 2014 
Nucleic Acids Research  2013;42(D1):D749-D755.
Ensembl (http://www.ensembl.org) creates tools and data resources to facilitate genomic analysis in chordate species with an emphasis on human, major vertebrate model organisms and farm animals. Over the past year we have increased the number of species that we support to 77 and expanded our genome browser with a new scrollable overview and improved variation and phenotype views. We also report updates to our core datasets and improvements to our gene homology relationships from the addition of new species. Our REST service has been extended with additional support for comparative genomics and ontology information. Finally, we provide updated information about our methods for data access and resources for user training.
doi:10.1093/nar/gkt1196
PMCID: PMC3964975  PMID: 24316576
3.  The European Bioinformatics Institute’s data resources 2014 
Nucleic Acids Research  2013;42(D1):D18-D25.
Molecular Biology has been at the heart of the ‘big data’ revolution from its very beginning, and the need for access to biological data is a common thread running from the 1965 publication of Dayhoff’s ‘Atlas of Protein Sequence and Structure’ through the Human Genome Project in the late 1990s and early 2000s to today’s population-scale sequencing initiatives. The European Bioinformatics Institute (EMBL-EBI; http://www.ebi.ac.uk) is one of three organizations worldwide that provides free access to comprehensive, integrated molecular data sets. Here, we summarize the principles underpinning the development of these public resources and provide an overview of EMBL-EBI’s database collection to complement the reviews of individual databases provided elsewhere in this issue.
doi:10.1093/nar/gkt1206
PMCID: PMC3964968  PMID: 24271396
4.  The Reactome pathway knowledgebase 
Nucleic Acids Research  2013;42(D1):D472-D477.
Reactome (http://www.reactome.org) is a manually curated open-source open-data resource of human pathways and reactions. The current version 46 describes 7088 human proteins (34% of the predicted human proteome), participating in 6744 reactions based on data extracted from 15 107 research publications with PubMed links. The Reactome Web site and analysis tool set have been completely redesigned to increase speed, flexibility and user friendliness. The data model has been extended to support annotation of disease processes due to infectious agents and to mutation.
doi:10.1093/nar/gkt1102
PMCID: PMC3965010  PMID: 24243840
5.  Toward practical high-capacity low-maintenance storage of digital information in synthesised DNA 
Nature  2013;494(7435):77-80.
The shift to digital systems for the creation, transmission and storage of information has led to increasing complexity in archiving, requiring active, ongoing maintenance of the digital media. DNA is an attractive target for information storage1 because of its capacity for high density information encoding, longevity under easily-achieved conditions2–4 and proven track record as an information bearer. Previous DNA-based information storage approaches have encoded only trivial amounts of information5–7 or were not amenable to scaling-up8, and used no robust error-correction and lacked examination of their cost-efficiency for large-scale information archival9. Here we describe a scalable method that can reliably store more information than has been handled before. We encoded computer files totalling 739 kB of hard disk storage and with an estimated Shannon information10 of 5.2 × 106 bits into a DNA code, synthesised this DNA, sequenced it and reconstructed the original files with 100% accuracy. Theoretical analysis indicates that our DNA-storage scheme scales far beyond current global information volumes. These results demonstrate DNA-storage to be a realistic technology for large-scale digital archiving that may already be cost-effective for low access, multi-century-long archiving tasks. Within a decade, as costs fall rapidly under realistic scenarios for technological advances, it may be cost-effective for sub-50-year archival.
doi:10.1038/nature11875
PMCID: PMC3672958  PMID: 23354052
6.  Highly conserved elements discovered in vertebrates are present in non-syntenic loci of tunicates, act as enhancers and can be transcribed during development 
Nucleic Acids Research  2013;41(6):3600-3618.
Co-option of cis-regulatory modules has been suggested as a mechanism for the evolution of expression sites during development. However, the extent and mechanisms involved in mobilization of cis-regulatory modules remains elusive. To trace the history of non-coding elements, which may represent candidate ancestral cis-regulatory modules affirmed during chordate evolution, we have searched for conserved elements in tunicate and vertebrate (Olfactores) genomes. We identified, for the first time, 183 non-coding sequences that are highly conserved between the two groups. Our results show that all but one element are conserved in non-syntenic regions between vertebrate and tunicate genomes, while being syntenic among vertebrates. Nevertheless, in all the groups, they are significantly associated with transcription factors showing specific functions fundamental to animal development, such as multicellular organism development and sequence-specific DNA binding. The majority of these regions map onto ultraconserved elements and we demonstrate that they can act as functional enhancers within the organism of origin, as well as in cross-transgenesis experiments, and that they are transcribed in extant species of Olfactores. We refer to the elements as ‘Olfactores conserved non-coding elements’.
doi:10.1093/nar/gkt030
PMCID: PMC3616699  PMID: 23393190
7.  Integrative annotation of chromatin elements from ENCODE data 
Nucleic Acids Research  2012;41(2):827-841.
The ENCODE Project has generated a wealth of experimental information mapping diverse chromatin properties in several human cell lines. Although each such data track is independently informative toward the annotation of regulatory elements, their interrelations contain much richer information for the systematic annotation of regulatory elements. To uncover these interrelations and to generate an interpretable summary of the massive datasets of the ENCODE Project, we apply unsupervised learning methodologies, converting dozens of chromatin datasets into discrete annotation maps of regulatory regions and other chromatin elements across the human genome. These methods rediscover and summarize diverse aspects of chromatin architecture, elucidate the interplay between chromatin activity and RNA transcription, and reveal that a large proportion of the genome lies in a quiescent state, even across multiple cell types. The resulting annotation of non-coding regulatory elements correlate strongly with mammalian evolutionary constraint, and provide an unbiased approach for evaluating metrics of evolutionary constraint in human. Lastly, we use the regulatory annotations to revisit previously uncharacterized disease-associated loci, resulting in focused, testable hypotheses through the lens of the chromatin landscape.
doi:10.1093/nar/gks1284
PMCID: PMC3553955  PMID: 23221638
8.  Ensembl 2013 
Nucleic Acids Research  2012;41(D1):D48-D55.
The Ensembl project (http://www.ensembl.org) provides genome information for sequenced chordate genomes with a particular focus on human, mouse, zebrafish and rat. Our resources include evidenced-based gene sets for all supported species; large-scale whole genome multiple species alignments across vertebrates and clade-specific alignments for eutherian mammals, primates, birds and fish; variation data resources for 17 species and regulation annotations based on ENCODE and other data sets. Ensembl data are accessible through the genome browser at http://www.ensembl.org and through other tools and programmatic interfaces.
doi:10.1093/nar/gks1236
PMCID: PMC3531136  PMID: 23203987
9.  Factorbook.org: a Wiki-based database for transcription factor-binding data generated by the ENCODE consortium 
Nucleic Acids Research  2012;41(D1):D171-D176.
The Encyclopedia of DNA Elements (ENCODE) consortium aims to identify all functional elements in the human genome including transcripts, transcriptional regulatory regions, along with their chromatin states and DNA methylation patterns. The ENCODE project generates data utilizing a variety of techniques that can enrich for regulatory regions, such as chromatin immunoprecipitation (ChIP), micrococcal nuclease (MNase) digestion and DNase I digestion, followed by deeply sequencing the resulting DNA. As part of the ENCODE project, we have developed a Web-accessible repository accessible at http://factorbook.org. In Wiki format, factorbook is a transcription factor (TF)-centric repository of all ENCODE ChIP-seq datasets on TF-binding regions, as well as the rich analysis results of these data. In the first release, factorbook contains 457 ChIP-seq datasets on 119 TFs in a number of human cell lines, the average profiles of histone modifications and nucleosome positioning around the TF-binding regions, sequence motifs enriched in the regions and the distance and orientation preferences between motif sites.
doi:10.1093/nar/gks1221
PMCID: PMC3531197  PMID: 23203885
10.  The genomic basis of adaptive evolution in threespine sticklebacks 
Nature  2012;484(7392):55-61.
Summary
Marine stickleback fish have colonized and adapted to innumerable streams and lakes formed since the last ice age, providing an exceptional opportunity to characterize genomic mechanisms underlying repeated ecological adaptation in nature. Here we develop a high quality reference genome assembly for threespine sticklebacks. By sequencing the genomes of 20 additional individuals from a global set of marine and freshwater populations, we identify a genome-wide set of loci that are consistently associated with marine-freshwater divergence. Our results suggest that reuse of globally-shared standing genetic variation, including chromosomal inversions, plays an important role in repeated evolution of distinct marine and freshwater sticklebacks, and in the maintenance of divergent ecotypes during early stages of reproductive isolation. Both coding and regulatory changes occur in the set of loci underlying marine-freshwater evolution, with regulatory changes likely predominating in this classic example of repeated adaptive evolution in nature.
doi:10.1038/nature10944
PMCID: PMC3322419  PMID: 22481358
11.  Classification of human genomic regions based on experimentally determined binding sites of more than 100 transcription-related factors 
Genome Biology  2012;13(9):R48.
Background
Transcription factors function by binding different classes of regulatory elements. The Encyclopedia of DNA Elements (ENCODE) project has recently produced binding data for more than 100 transcription factors from about 500 ChIP-seq experiments in multiple cell types. While this large amount of data creates a valuable resource, it is nonetheless overwhelmingly complex and simultaneously incomplete since it covers only a small fraction of all human transcription factors.
Results
As part of the consortium effort in providing a concise abstraction of the data for facilitating various types of downstream analyses, we constructed statistical models that capture the genomic features of three paired types of regions by machine-learning methods: firstly, regions with active or inactive binding; secondly, those with extremely high or low degrees of co-binding, termed HOT and LOT regions; and finally, regulatory modules proximal or distal to genes. From the distal regulatory modules, we developed computational pipelines to identify potential enhancers, many of which were validated experimentally. We further associated the predicted enhancers with potential target transcripts and the transcription factors involved. For HOT regions, we found a significant fraction of transcription factor binding without clear sequence motifs and showed that this observation could be related to strong DNA accessibility of these regions.
Conclusions
Overall, the three pairs of regions exhibit intricate differences in chromosomal locations, chromatin features, factors that bind them, and cell-type specificity. Our machine learning approach enables us to identify features potentially general to all transcription factors, including those not included in the data.
doi:10.1186/gb-2012-13-9-r48
PMCID: PMC3491392  PMID: 22950945
12.  Analysis of variation at transcription factor binding sites in Drosophila and humans 
Genome Biology  2012;13(9):R49.
Background
Advances in sequencing technology have boosted population genomics and made it possible to map the positions of transcription factor binding sites (TFBSs) with high precision. Here we investigate TFBS variability by combining transcription factor binding maps generated by ENCODE, modENCODE, our previously published data and other sources with genomic variation data for human individuals and Drosophila isogenic lines.
Results
We introduce a metric of TFBS variability that takes into account changes in motif match associated with mutation and makes it possible to investigate TFBS functional constraints instance-by-instance as well as in sets that share common biological properties. We also take advantage of the emerging per-individual transcription factor binding data to show evidence that TFBS mutations, particularly at evolutionarily conserved sites, can be efficiently buffered to ensure coherent levels of transcription factor binding.
Conclusions
Our analyses provide insights into the relationship between individual and interspecies variation and show evidence for the functional buffering of TFBS mutations in both humans and flies. In a broad perspective, these results demonstrate the potential of combining functional genomics and population genetics approaches for understanding gene regulation.
doi:10.1186/gb-2012-13-9-r49
PMCID: PMC3491393  PMID: 22950968
13.  Modeling gene expression using chromatin features in various cellular contexts 
Genome Biology  2012;13(9):R53.
Background
Previous work has demonstrated that chromatin feature levels correlate with gene expression. The ENCODE project enables us to further explore this relationship using an unprecedented volume of data. Expression levels from more than 100,000 promoters were measured using a variety of high-throughput techniques applied to RNA extracted by different protocols from different cellular compartments of several human cell lines. ENCODE also generated the genome-wide mapping of eleven histone marks, one histone variant, and DNase I hypersensitivity sites in seven cell lines.
Results
We built a novel quantitative model to study the relationship between chromatin features and expression levels. Our study not only confirms that the general relationships found in previous studies hold across various cell lines, but also makes new suggestions about the relationship between chromatin features and gene expression levels. We found that expression status and expression levels can be predicted by different groups of chromatin features, both with high accuracy. We also found that expression levels measured by CAGE are better predicted than by RNA-PET or RNA-Seq, and different categories of chromatin features are the most predictive of expression for different RNA measurement methods. Additionally, PolyA+ RNA is overall more predictable than PolyA- RNA among different cell compartments, and PolyA+ cytosolic RNA measured with RNA-Seq is more predictable than PolyA+ nuclear RNA, while the opposite is true for PolyA- RNA.
Conclusions
Our study provides new insights into transcriptional regulation by analyzing chromatin features in different cellular contexts.
doi:10.1186/gb-2012-13-9-r53
PMCID: PMC3491397  PMID: 22950368
14.  The future of DNA sequence archiving 
GigaScience  2012;1:2.
Archives operating under the International Nucleotide Sequence Database Collaboration currently preserve all submitted sequences equally, but rapid increases in the rate of global sequence production will soon require differentiated treatment of DNA sequences submitted for archiving. Here, we propose a graded system in which the ease of reproduction of a sequencing-based experiment and the relative availability of a sample for resequencing define the level of lossy compression applied to stored data.
doi:10.1186/2047-217X-1-2
PMCID: PMC3617450  PMID: 23587147
DNA; Sequence; Archive; Compression; Storage; Image
15.  Mouse genomic variation and its effect on phenotypes and gene regulation 
Nature  2011;477(7364):289-294.
We report genome sequences of 17 inbred strains of laboratory mice and identify almost ten times more variants than previously known. We use these genomes to explore the phylogenetic history of the laboratory mouse and to examine the functional consequences of allele-specific variation on transcript abundance, revealing that at least 12% of transcripts show a significant tissue-specific expression bias. By identifying candidate functional variants at 718 quantitative trait loci we show that the molecular nature of functional variants and their position relative to genes vary according to the effect size of the locus. These sequences provide a starting point for a new era in the functional analysis of a key model organism.
doi:10.1038/nature10413
PMCID: PMC3276836  PMID: 21921910
16.  Oases: robust de novo RNA-seq assembly across the dynamic range of expression levels 
Bioinformatics  2012;28(8):1086-1092.
Motivation: High-throughput sequencing has made the analysis of new model organisms more affordable. Although assembling a new genome can still be costly and difficult, it is possible to use RNA-seq to sequence mRNA. In the absence of a known genome, it is necessary to assemble these sequences de novo, taking into account possible alternative isoforms and the dynamic range of expression values.
Results: We present a software package named Oases designed to heuristically assemble RNA-seq reads in the absence of a reference genome, across a broad spectrum of expression values and in presence of alternative isoforms. It achieves this by using an array of hash lengths, a dynamic filtering of noise, a robust resolution of alternative splicing events and the efficient merging of multiple assemblies. It was tested on human and mouse RNA-seq data and is shown to improve significantly on the transABySS and Trinity de novo transcriptome assemblers.
Availability and implementation: Oases is freely available under the GPL license at www.ebi.ac.uk/~zerbino/oases/
Contact: dzerbino@ucsc.edu
Supplementary information: Supplementary data are available at Bioinformatics online.
doi:10.1093/bioinformatics/bts094
PMCID: PMC3324515  PMID: 22368243
17.  Considerations for the inclusion of 2x mammalian genomes in phylogenetic analyses 
Genome Biology  2011;12(2):401.
A response to 2x genomes - depth does matter by MC Milinkovitch, R Helaers, E Depiereux, AC Tzika and T Gabaldón. Genome Biol 2010, 11:R16.
doi:10.1186/gb-2011-12-2-401
PMCID: PMC3188792  PMID: 21320298
18.  Ensembl 2012 
Nucleic Acids Research  2011;40(D1):D84-D90.
The Ensembl project (http://www.ensembl.org) provides genome resources for chordate genomes with a particular focus on human genome data as well as data for key model organisms such as mouse, rat and zebrafish. Five additional species were added in the last year including gibbon (Nomascus leucogenys) and Tasmanian devil (Sarcophilus harrisii) bringing the total number of supported species to 61 as of Ensembl release 64 (September 2011). Of these, 55 species appear on the main Ensembl website and six species are provided on the Ensembl preview site (Pre!Ensembl; http://pre.ensembl.org) with preliminary support. The past year has also seen improvements across the project.
doi:10.1093/nar/gkr991
PMCID: PMC3245178  PMID: 22086963
19.  Major submissions tool developments at the European nucleotide archive 
Nucleic Acids Research  2011;40(D1):D43-D47.
The European Nucleotide Archive (ENA; http://www.ebi.ac.uk/ena), Europe's primary nucleotide sequence resource, captures and presents globally comprehensive nucleic acid sequence and associated information. Covering the spectrum from raw data to assembled and functionally annotated genomes, the ENA has witnessed a dramatic growth resulting from advances in sequencing technology and ever broadening application of the methodology. During 2011, we have continued to operate and extend the broad range of ENA services. In particular, we have released major new functionality in our interactive web submission system, Webin, through developments in template-based submissions for annotated sequences and support for raw next-generation sequence read submissions.
doi:10.1093/nar/gkr946
PMCID: PMC3245037  PMID: 22080548
20.  Ensembl Genomes: an integrative resource for genome-scale data from non-vertebrate species 
Nucleic Acids Research  2011;40(D1):D91-D97.
Ensembl Genomes (http://www.ensemblgenomes.org) is an integrative resource for genome-scale data from non-vertebrate species. The project exploits and extends technology (for genome annotation, analysis and dissemination) developed in the context of the (vertebrate-focused) Ensembl project and provides a complementary set of resources for non-vertebrate species through a consistent set of programmatic and interactive interfaces. These provide access to data including reference sequence, gene models, transcriptional data, polymorphisms and comparative analysis. Since its launch in 2009, Ensembl Genomes has undergone rapid expansion, with the goal of providing coverage of all major experimental organisms, and additionally including taxonomic reference points to provide the evolutionary context in which genes can be understood. Against the backdrop of a continuing increase in genome sequencing activities in all parts of the tree of life, we seek to work, wherever possible, with the communities actively generating and using data, and are participants in a growing range of collaborations involved in the annotation and analysis of genomes.
doi:10.1093/nar/gkr895
PMCID: PMC3245118  PMID: 22067447
21.  Allele-specific and heritable chromatin signatures in humans 
Human Molecular Genetics  2010;19(R2):R204-R209.
Next-generation sequencing-based assays to detect gene regulatory elements are enabling the analysis of individual-to-individual and allele-specific variation of chromatin status and transcription factor binding in humans. Recently, a number of studies have explored this area, using lymphoblastoid cell lines. Around 10% of chromatin sites show either individual-level differences or allele-specific behavior. Future studies are likely to be limited by cell line accessibility, meaning that white-bloodcell-based studies are likely to continue to be the main source of samples. A detailed understanding of the relationship between normal genetic variation and chromatin variation can shed light on how polymorphisms in non-coding regions in the human genome might underlie phenotypic variation and disease.
doi:10.1093/hmg/ddq404
PMCID: PMC2953746  PMID: 20846943
22.  Mapping Identifiers for the Integration of Genomic Datasets with the R/Bioconductor package biomaRt 
Nature protocols  2009;4(8):1184-1191.
Genomic experiments produce multiple views of biological systems, among them DNA sequence and copy number variation, mRNA and protein abundance. Understanding these systems requires integrated bioinformatic analysis. Public databases such as Ensembl provide relationships and mappings between the relevant sets of probe and target molecules. However, the relationships can be biologically complex and the content of the databases is dynamic. We demonstrate how to use the computational environment R to integrate and jointly analyse experimental datasets, employing BioMart web services to provide the molecule mappings. We also discuss typical problems that are encountered in making gene to transcript to protein mappings. The approach provides a flexible, programmable and reproducible basis for state-of-the-art bioinformatic data integration.
doi:10.1038/nprot.2009.97
PMCID: PMC3159387  PMID: 19617889
Data Integration; Mapping; Identifiers; Ensembl; BioMart; Bioconductor
23.  Genomic information infrastructure after the deluge 
Genome Biology  2010;11(7):402.
Maintaining up-to-date annotation on reference genomes is becoming more important, not less, as the ability to rapidly and cheaply resequence genomes expands.
doi:10.1186/gb-2010-11-7-402
PMCID: PMC2926780  PMID: 20670392
24.  Reactome: a database of reactions, pathways and biological processes 
Nucleic Acids Research  2010;39(Database issue):D691-D697.
Reactome (http://www.reactome.org) is a collaboration among groups at the Ontario Institute for Cancer Research, Cold Spring Harbor Laboratory, New York University School of Medicine and The European Bioinformatics Institute, to develop an open source curated bioinformatics database of human pathways and reactions. Recently, we developed a new web site with improved tools for pathway browsing and data analysis. The Pathway Browser is an Systems Biology Graphical Notation (SBGN)-based visualization system that supports zooming, scrolling and event highlighting. It exploits PSIQUIC web services to overlay our curated pathways with molecular interaction data from the Reactome Functional Interaction Network and external interaction databases such as IntAct, BioGRID, ChEMBL, iRefIndex, MINT and STRING. Our Pathway and Expression Analysis tools enable ID mapping, pathway assignment and overrepresentation analysis of user-supplied data sets. To support pathway annotation and analysis in other species, we continue to make orthology-based inferences of pathways in non-human species, applying Ensembl Compara to identify orthologs of curated human proteins in each of 20 other species. The resulting inferred pathway sets can be browsed and analyzed with our Species Comparison tool. Collaborations are also underway to create manually curated data sets on the Reactome framework for chicken, Drosophila and rice.
doi:10.1093/nar/gkq1018
PMCID: PMC3013646  PMID: 21067998
25.  Ensembl 2011 
Nucleic Acids Research  2010;39(Database issue):D800-D806.
The Ensembl project (http://www.ensembl.org) seeks to enable genomic science by providing high quality, integrated annotation on chordate and selected eukaryotic genomes within a consistent and accessible infrastructure. All supported species include comprehensive, evidence-based gene annotations and a selected set of genomes includes additional data focused on variation, comparative, evolutionary, functional and regulatory annotation. The most advanced resources are provided for key species including human, mouse, rat and zebrafish reflecting the popularity and importance of these species in biomedical research. As of Ensembl release 59 (August 2010), 56 species are supported of which 5 have been added in the past year. Since our previous report, we have substantially improved the presentation and integration of both data of disease relevance and the regulatory state of different cell types.
doi:10.1093/nar/gkq1064
PMCID: PMC3013672  PMID: 21045057

Results 1-25 (66)