Igor Antoshechkin

Landscape of transcription in human cells

Eukaryotic cells make many types of primary and processed RNAs that are found either in specific subcellular compartments or throughout the cells. A complete catalogue of these RNAs is not yet available and their characteristic subcellular localizations are also poorly understood. Because RNA represents the direct output of the genetic information encoded by genomes and a significant proportion of a cell’s regulatory capabilities are focused on its synthesis, processing, transport, modification and translation, the generation of such a catalogue is crucial for understanding genome function. Here we report evidence that three-quarters of the human genome is capable of being transcribed, as well as observations about the range and levels of expression, localization, processing fates, regulatory regions and modifications of almost all currently annotated and thousands of previously unannotated RNAs. These observations, taken together, prompt a redefinition of the concept of a gene.

WormBase: a multi-species resource for nematode biology and genomics.

WormBase (http://www.wormbase.org/) is the central data repository for information about Caenorhabditis elegans and related nematodes. As a model organism database, WormBase extends beyond the genomic sequence, integrating experimental results with extensively annotated views of the genome. The WormBase Consortium continues to expand the biological scope and utility of WormBase with the inclusion of large-scale genomic analyses, through active data and literature curation, through new analysis and visualization tools, and through refinement of the user interface. Over the past year, the nearly complete genomic sequence and comparative analyses of the closely related species Caenorhabditis briggsae have been integrated into WormBase, including gene predictions, ortholog assignments and a new synteny viewer to display the relationships between the two species. Extensive site-wide refinement of the user interface now provides quick access to the most frequently accessed resources and a consistent browsing experience across the site. Unified single-page views now provide complete summaries of commonly accessed entries like genes. These advances continue to increase the utility of WormBase for C.elegans researchers, as well as for those researchers exploring problems in functional and comparative genomics in the context of a powerful genetic system.

WormBase: a comprehensive resource for nematode research

WormBase (http://www.wormbase.org) is a central data repository for nematode biology. Initially created as a service to the Caenorhabditis elegans research field, WormBase has evolved into a powerful research tool in its own right. In the past 2 years, we expanded WormBase to include the complete genomic sequence, gene predictions and orthology assignments from a range of related nematodes. This comparative data enrich the C. elegans data with improved gene predictions and a better understanding of gene function. In turn, they bring the wealth of experimental knowledge of C. elegans to other systems of medical and agricultural importance. Here, we describe new species and data types now available at WormBase. In addition, we detail enhancements to our curatorial pipeline and website infrastructure to accommodate new genomes and an extensive user base.

WormBase: a comprehensive data resource for Caenorhabditis biology and genomics

WormBase (http://www.wormbase.org), the model organism database for information about Caenorhabditis elegans and related nematodes, continues to expand in breadth and depth. Over the past year, WormBase has added multiple large-scale datasets including SAGE, interactome, 3D protein structure datasets and NCBI KOGs. To accommodate this growth, the International WormBase Consortium has improved the user interface by adding new features to aid in navigation, visualization of large-scale datasets, advanced searching and data mining. Internally, we have restructured the database models to rationalize the representation of genes and to prepare the system to accept the genome sequences of three additional Caenorhabditis species over the coming year.

The genome and developmental transcriptome of the strongylid nematode Haemonchus contortus

BackgroundThe barbers pole worm, Haemonchus contortus, is one of the most economically important parasites of small ruminants worldwide. Although this parasite can be controlled using anthelmintic drugs, resistance against most drugs in common use has become a widespread problem. We provide a draft of the genome and the transcriptomes of all key developmental stages of H. contortus to support biological and biotechnological research areas of this and related parasites.ResultsThe draft genome of H. contortus is 320 Mb in size and encodes 23,610 protein-coding genes. On a fundamental level, we elucidate transcriptional alterations taking place throughout the life cycle, characterize the parasites gene silencing machinery, and explore molecules involved in development, reproduction, host-parasite interactions, immunity, and disease. The secretome of H. contortus is particularly rich in peptidases linked to blood-feeding activity and interactions with host tissues, and a diverse array of molecules is involved in complex immune responses. On an applied level, we predict drug targets and identify vaccine molecules.ConclusionsThe draft genome and developmental transcriptome of H. contortus provide a major resource to the scientific community for a wide range of genomic, genetic, proteomic, metabolomic, evolutionary, biological, ecological, and epidemiological investigations, and a solid foundation for biotechnological outcomes, including new anthelmintics, vaccines and diagnostic tests. This first draft genome of any strongylid nematode paves the way for a rapid acceleration in our understanding of a wide range of socioeconomically important parasites of one of the largest nematode orders.

A large-scale in vivo analysis reveals that TALENs are significantly more mutagenic than ZFNs generated using context-dependent assembly

Zinc-finger nucleases (ZFNs) and TAL effector nucleases (TALENs) have been shown to induce targeted mutations, but they have not been extensively tested in any animal model. Here, we describe a large-scale comparison of ZFN and TALEN mutagenicity in zebrafish. Using deep sequencing, we found that TALENs are significantly more likely to be mutagenic and induce an average of 10-fold more mutations than ZFNs. We observed a strong correlation between somatic and germ-line mutagenicity, and identified germ line mutations using ZFNs whose somatic mutations rates are well below the commonly used threshold of 1%. Guidelines that have previously been proposed to predict optimal ZFN and TALEN target sites did not predict mutagenicity in vivo. However, we observed a significant negative correlation between TALEN mutagenicity and the number of CpG repeats in TALEN target sites, suggesting that target site methylation may explain the poor mutagenicity of some TALENs in vivo. The higher mutation rates and ability to target essentially any sequence make TALENs the superior technology for targeted mutagenesis in zebrafish, and likely other animal models.

The versatile worm: genetic and genomic resources for Caenorhabditis elegans research

Since its establishment as a model organism, Caenorhabditis elegans has been an invaluable tool for biological research. An immense spectrum of questions can be addressed using this small nematode, making it one of the most versatile and exciting model organisms. Although the many tools and resources developed by the C. elegans community greatly facilitate new discoveries, they can also overwhelm newcomers to the field. This Review aims to familiarize new worm researchers with the main resources, and help them to select the tools that are best suited for their needs. We also hope that it will be helpful in identifying new research opportunities and will promote the development of additional resources.

WormBase: new content and better access

WormBase (), a model organism database for Caenorhabditis elegans and other related nematodes, continues to evolve and expand. Over the past year WormBase has added new data on C.elegans, including data on classical genetics, cell biology and functional genomics; expanded the annotation of closely related nematodes with a new genome browser for Caenorhabditis remanei; and deployed new hardware for stronger performance. Several existing datasets including phenotype descriptions and RNAi experiments have seen a large increase in new content. New datasets such as the C.remanei draft assembly and annotations, the Vancouver Fosmid library and TEC-RED 5′ end sites are now available as well. Access to and searching WormBase has become more dependable and flexible via multiple mirror sites and indexing through Google.

WormBase: better software, richer content

WormBase (), the public database for genomics and biology of Caenorhabditis elegans, has been restructured for stronger performance and expanded for richer biological content. Performance was improved by accelerating the loading of central data pages such as the omnibus Gene page, by rationalizing internal data structures and software for greater portability, and by making the Genome Browser highly customizable in how it views and exports genomic subsequences. Arbitrarily complex, user-specified queries are now possible through Textpresso (for all available literature) and through WormMart (for most genomic data). Biological content was enriched by reconciling all available cDNA and expressed sequence tag data with gene predictions, clarifying single nucleotide polymorphism and RNAi sites, and summarizing known functions for most genes studied in this organism.

Scaffolding a Caenorhabditis nematode genome with RNA-seq

Efficient sequencing of animal and plant genomes by next-generation technology should allow many neglected organisms of biological and medical importance to be better understood. As a test case, we have assembled a draft genome of Caenorhabditis sp. 3 PS1010 through a combination of direct sequencing and scaffolding with RNA-seq. We first sequenced genomic DNA and mixed-stage cDNA using paired 75-nt reads from an Illumina GAII. A set of 230 million genomic reads yielded an 80-Mb assembly, with a supercontig N50 of 5.0 kb, covering 90% of 429 kb from previously published genomic contigs. Mixed-stage poly(A)(+) cDNA gave 47.3 million mappable 75-mers (including 5.1 million spliced reads), which separately assembled into 17.8 Mb of cDNA, with an N50 of 1.06 kb. By further scaffolding our genomic supercontigs with cDNA, we increased their N50 to 9.4 kb, nearly double the average gene size in C. elegans. We predicted 22,851 protein-coding genes, and detected expression in 78% of them. Multigenome alignment and data filtering identified 2672 DNA elements conserved between PS1010 and C. elegans that are likely to encode regulatory sequences or previously unknown ncRNAs. Genomic and cDNA sequencing followed by joint assembly is a rapid and useful strategy for biological analysis.