TogoID: an exploratory ID converter to bridge biological datasets.

MOTIVATION: Understanding life cannot be accomplished without making full use of biological data, which are scattered across databases of diverse categories in life sciences. To connect such data seamlessly, identifier (ID) conversion plays a key role. However, existing ID conversion services have disadvantages, such as covering only a limited range of biological categories of databases, not keeping up with the updates of the original databases and outputs being hard to interpret in the context of biological relations, especially when converting IDs in multiple steps. RESULTS: TogoID is an ID conversion service implementing unique features with an intuitive web interface and an application programming interface (API) for programmatic access. TogoID currently supports 65 datasets covering various biological categories. TogoID users can perform exploratory multistep conversions to find a path among IDs. To guide the interpretation of biological meanings in the conversions, we crafted an ontology that defines the semantics of the dataset relations. AVAILABILITY AND IMPLEMENTATION: The TogoID service is freely available on the TogoID website (https://togoid.dbcls.jp/) and the API is also provided to allow programmatic access. To encourage developers to add new dataset pairs, the system stores the configurations of pairs at the GitHub repository (https://github.com/togoid/togoid-config) and accepts the request of additional pairs. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

TogoGenome/TogoStanza: modularized Semantic Web genome database.

TogoGenome is a genome database that is purely based on the Semantic Web technology, which enables the integration of heterogeneous data and flexible semantic searches. All the information is stored as Resource Description Framework (RDF) data, and the reporting web pages are generated on the fly using SPARQL Protocol and RDF Query Language (SPARQL) queries. TogoGenome provides a semantic-faceted search system by gene functional annotation, taxonomy, phenotypes and environment based on the relevant ontologies. TogoGenome also serves as an interface to conduct semantic comparative genomics by which a user can observe pan-organism or organism-specific genes based on the functional aspect of gene annotations and the combinations of organisms from different taxa. The TogoGenome database exhibits a modularized structure, and each module in the report pages is separately served as TogoStanza, which is a generic framework for rendering an information block as IFRAME/Web Components, which can, unlike several other monolithic databases, also be reused to construct other databases. TogoGenome and TogoStanza have been under development since 2012 and are freely available along with their source codes on the GitHub repositories at https://github.com/togogenome/ and https://github.com/togostanza/, respectively, under the MIT license.

Implementation of linked data in the life sciences at BioHackathon 2011.

BACKGROUND: Linked Data has gained some attention recently in the life sciences as an effective way to provide and share data. As a part of the Semantic Web, data are linked so that a person or machine can explore the web of data. Resource Description Framework (RDF) is the standard means of implementing Linked Data. In the process of generating RDF data, not only are data simply linked to one another, the links themselves are characterized by ontologies, thereby allowing the types of links to be distinguished. Although there is a high labor cost to define an ontology for data providers, the merit lies in the higher level of interoperability with data analysis and visualization software. This increase in interoperability facilitates the multi-faceted retrieval of data, and the appropriate data can be quickly extracted and visualized. Such retrieval is usually performed using the SPARQL (SPARQL Protocol and RDF Query Language) query language, which is used to query RDF data stores. For the database provider, such interoperability will surely lead to an increase in the number of users. RESULTS: This manuscript describes the experiences and discussions shared among participants of the week-long BioHackathon 2011 who went through the development of RDF representations of their own data and developed specific RDF and SPARQL use cases. Advice regarding considerations to take when developing RDF representations of their data are provided for bioinformaticians considering making data available and interoperable. CONCLUSIONS: Participants of the BioHackathon 2011 were able to produce RDF representations of their data and gain a better understanding of the requirements for producing such data in a period of just five days. We summarize the work accomplished with the hope that it will be useful for researchers involved in developing laboratory databases or data analysis, and those who are considering such technologies as RDF and Linked Data.

Loss of cytochrome cM stimulates cyanobacterial heterotrophic growth in the dark.

Although cyanobacteria are photoautotrophs, they have the capability for heterotrophic metabolism that enables them to survive in their natural habitat. However, cyanobacterial species that grow heterotrophically in the dark are rare. It remains largely unknown how cyanobacteria regulate heterotrophic activity. The cyanobacterium Leptolyngbya boryana grows heterotrophically with glucose in the dark. A dark-adapted variant dg5 isolated from the wild type (WT) exhibits enhanced heterotrophic growth in the dark. We sequenced the genomes of dg5 and the WT to identify the mutation(s) of dg5. The WT genome consists of a circular chromosome (6,176,364 bp), a circular plasmid pLBA (77,793 bp) and two linear plasmids pLBX (504,942 bp) and pLBY (44,369 bp). Genome comparison revealed three mutation sites. Phenotype analysis of mutants isolated from the WT by introducing these mutations individually revealed that the relevant mutation is a single adenine insertion causing a frameshift of cytM encoding Cyt c(M). The respiratory oxygen consumption of the cytM-lacking mutant grown in the dark was significantly higher than that of the WT. We isolated a cytM-lacking mutant, ΔcytM, from another cyanobacterium Synechocystis sp. PCC 6803, and ΔcytM grew in the dark with a doubling time of 33 h in contrast to no growth of the WT. The respiratory oxygen consumption of ΔcytM grown in the dark was about 2-fold higher than that of the WT. These results suggest a suppressive role(s) for Cyt cM in regulation of heterotrophic activity.

PIERO ontology for analysis of biochemical transformations: effective implementation of reaction information in the IUBMB enzyme list.

Genomics is faced with the issue of many partially annotated putative enzyme-encoding genes for which activities have not yet been verified, while metabolomics is faced with the issue of many putative enzyme reactions for which full equations have not been verified. Knowledge of enzymes has been collected by IUBMB, and has been made public as the Enzyme List. To date, however, the terminology of the Enzyme List has not been assessed comprehensively by bioinformatics studies. Instead, most of the bioinformatics studies simply use the identifiers of the enzymes, i.e. the Enzyme Commission (EC) numbers. We investigated the actual usage of terminology throughout the Enzyme List, and demonstrated that the partial characteristics of reactions cannot be retrieved by simply using EC numbers. Thus, we developed a novel ontology, named PIERO, for annotating biochemical transformations as follows. First, the terminology describing enzymatic reactions was retrieved from the Enzyme List, and was grouped into those related to overall reactions and biochemical transformations. Consequently, these terms were mapped onto the actual transformations taken from enzymatic reaction equations. This ontology was linked to Gene Ontology (GO) and EC numbers, allowing the extraction of common partial reaction characteristics from given sets of orthologous genes and the elucidation of possible enzymes from the given transformations. Further future development of the PIERO ontology should enhance the Enzyme List to promote the integration of genomics and metabolomics.

BioHackathon series in 2011 and 2012: penetration of ontology and linked data in life science domains.

The application of semantic technologies to the integration of biological data and the interoperability of bioinformatics analysis and visualization tools has been the common theme of a series of annual BioHackathons hosted in Japan for the past five years. Here we provide a review of the activities and outcomes from the BioHackathons held in 2011 in Kyoto and 2012 in Toyama. In order to efficiently implement semantic technologies in the life sciences, participants formed various sub-groups and worked on the following topics: Resource Description Framework (RDF) models for specific domains, text mining of the literature, ontology development, essential metadata for biological databases, platforms to enable efficient Semantic Web technology development and interoperability, and the development of applications for Semantic Web data. In this review, we briefly introduce the themes covered by these sub-groups. The observations made, conclusions drawn, and software development projects that emerged from these activities are discussed.

CyanoBase and RhizoBase: databases of manually curated annotations for cyanobacterial and rhizobial genomes.

To understand newly sequenced genomes of closely related species, comprehensively curated reference genome databases are becoming increasingly important. We have extended CyanoBase (http://genome.microbedb.jp/cyanobase), a genome database for cyanobacteria, and newly developed RhizoBase (http://genome.microbedb.jp/rhizobase), a genome database for rhizobia, nitrogen-fixing bacteria associated with leguminous plants. Both databases focus on the representation and reusability of reference genome annotations, which are continuously updated by manual curation. Domain experts have extracted names, products and functions of each gene reported in the literature. To ensure effectiveness of this procedure, we developed the TogoAnnotation system offering a web-based user interface and a uniform storage of annotations for the curators of the CyanoBase and RhizoBase databases. The number of references investigated for CyanoBase increased from 2260 in our previous report to 5285, and for RhizoBase, we perused 1216 references. The results of these intensive annotations are displayed on the GeneView pages of each database. Advanced users can also retrieve this information through the representational state transfer-based web application programming interface in an automated manner.

The 3rd DBCLS BioHackathon: improving life science data integration with Semantic Web technologies.

BACKGROUND: BioHackathon 2010 was the third in a series of meetings hosted by the Database Center for Life Sciences (DBCLS) in Tokyo, Japan. The overall goal of the BioHackathon series is to improve the quality and accessibility of life science research data on the Web by bringing together representatives from public databases, analytical tool providers, and cyber-infrastructure researchers to jointly tackle important challenges in the area of in silico biological research. RESULTS: The theme of BioHackathon 2010 was the 'Semantic Web', and all attendees gathered with the shared goal of producing Semantic Web data from their respective resources, and/or consuming or interacting those data using their tools and interfaces. We discussed on topics including guidelines for designing semantic data and interoperability of resources. We consequently developed tools and clients for analysis and visualization. CONCLUSION: We provide a meeting report from BioHackathon 2010, in which we describe the discussions, decisions, and breakthroughs made as we moved towards compliance with Semantic Web technologies - from source provider, through middleware, to the end-consumer.

Complete genome sequence of Bradyrhizobium sp. S23321: insights into symbiosis evolution in soil oligotrophs.

Bradyrhizobium sp. S23321 is an oligotrophic bacterium isolated from paddy field soil. Although S23321 is phylogenetically close to Bradyrhizobium japonicum USDA110, a legume symbiont, it is unable to induce root nodules in siratro, a legume often used for testing Nod factor-dependent nodulation. The genome of S23321 is a single circular chromosome, 7,231,841 bp in length, with an average GC content of 64.3%. The genome contains 6,898 potential protein-encoding genes, one set of rRNA genes, and 45 tRNA genes. Comparison of the genome structure between S23321 and USDA110 showed strong colinearity; however, the symbiosis islands present in USDA110 were absent in S23321, whose genome lacked a chaperonin gene cluster (groELS3) for symbiosis regulation found in USDA110. A comparison of sequences around the tRNA-Val gene strongly suggested that S23321 contains an ancestral-type genome that precedes the acquisition of a symbiosis island by horizontal gene transfer. Although S23321 contains a nif (nitrogen fixation) gene cluster, the organization, homology, and phylogeny of the genes in this cluster were more similar to those of photosynthetic bradyrhizobia ORS278 and BTAi1 than to those on the symbiosis island of USDA110. In addition, we found genes encoding a complete photosynthetic system, many ABC transporters for amino acids and oligopeptides, two types (polar and lateral) of flagella, multiple respiratory chains, and a system for lignin monomer catabolism in the S23321 genome. These features suggest that S23321 is able to adapt to a wide range of environments, probably including low-nutrient conditions, with multiple survival strategies in soil and rhizosphere.

The 2nd DBCLS BioHackathon: interoperable bioinformatics Web services for integrated applications.

BACKGROUND: The interaction between biological researchers and the bioinformatics tools they use is still hampered by incomplete interoperability between such tools. To ensure interoperability initiatives are effectively deployed, end-user applications need to be aware of, and support, best practices and standards. Here, we report on an initiative in which software developers and genome biologists came together to explore and raise awareness of these issues: BioHackathon 2009. RESULTS: Developers in attendance came from diverse backgrounds, with experts in Web services, workflow tools, text mining and visualization. Genome biologists provided expertise and exemplar data from the domains of sequence and pathway analysis and glyco-informatics. One goal of the meeting was to evaluate the ability to address real world use cases in these domains using the tools that the developers represented. This resulted in i) a workflow to annotate 100,000 sequences from an invertebrate species; ii) an integrated system for analysis of the transcription factor binding sites (TFBSs) enriched based on differential gene expression data obtained from a microarray experiment; iii) a workflow to enumerate putative physical protein interactions among enzymes in a metabolic pathway using protein structure data; iv) a workflow to analyze glyco-gene-related diseases by searching for human homologs of glyco-genes in other species, such as fruit flies, and retrieving their phenotype-annotated SNPs. CONCLUSIONS: Beyond deriving prototype solutions for each use-case, a second major purpose of the BioHackathon was to highlight areas of insufficiency. We discuss the issues raised by our exploration of the problem/solution space, concluding that there are still problems with the way Web services are modeled and annotated, including: i) the absence of several useful data or analysis functions in the Web service "space"; ii) the lack of documentation of methods; iii) lack of compliance with the SOAP/WSDL specification among and between various programming-language libraries; and iv) incompatibility between various bioinformatics data formats. Although it was still difficult to solve real world problems posed to the developers by the biological researchers in attendance because of these problems, we note the promise of addressing these issues within a semantic framework.

The DBCLS BioHackathon: standardization and interoperability for bioinformatics web services and workflows. The DBCLS BioHackathon Consortium*.

Web services have become a key technology for bioinformatics, since life science databases are globally decentralized and the exponential increase in the amount of available data demands for efficient systems without the need to transfer entire databases for every step of an analysis. However, various incompatibilities among database resources and analysis services make it difficult to connect and integrate these into interoperable workflows. To resolve this situation, we invited domain specialists from web service providers, client software developers, Open Bio* projects, the BioMoby project and researchers of emerging areas where a standard exchange data format is not well established, for an intensive collaboration entitled the BioHackathon 2008. The meeting was hosted by the Database Center for Life Science (DBCLS) and Computational Biology Research Center (CBRC) and was held in Tokyo from February 11th to 15th, 2008. In this report we highlight the work accomplished and the common issues arisen from this event, including the standardization of data exchange formats and services in the emerging fields of glycoinformatics, biological interaction networks, text mining, and phyloinformatics. In addition, common shared object development based on BioSQL, as well as technical challenges in large data management, asynchronous services, and security are discussed. Consequently, we improved interoperability of web services in several fields, however, further cooperation among major database centers and continued collaborative efforts between service providers and software developers are still necessary for an effective advance in bioinformatics web service technologies.

Genomic structure of an economically important cyanobacterium, Arthrospira (Spirulina) platensis NIES-39.

A filamentous non-N(2)-fixing cyanobacterium, Arthrospira (Spirulina) platensis, is an important organism for industrial applications and as a food supply. Almost the complete genome of A. platensis NIES-39 was determined in this study. The genome structure of A. platensis is estimated to be a single, circular chromosome of 6.8 Mb, based on optical mapping. Annotation of this 6.7 Mb sequence yielded 6630 protein-coding genes as well as two sets of rRNA genes and 40 tRNA genes. Of the protein-coding genes, 78% are similar to those of other organisms; the remaining 22% are currently unknown. A total 612 kb of the genome comprise group II introns, insertion sequences and some repetitive elements. Group I introns are located in a protein-coding region. Abundant restriction-modification systems were determined. Unique features in the gene composition were noted, particularly in a large number of genes for adenylate cyclase and haemolysin-like Ca(2+)-binding proteins and in chemotaxis proteins. Filament-specific genes were highlighted by comparative genomic analysis.

CyanoBase: the cyanobacteria genome database update 2010.

CyanoBase (http://genome.kazusa.or.jp/cyanobase) is the genome database for cyanobacteria, which are model organisms for photosynthesis. The database houses cyanobacteria species information, complete genome sequences, genome-scale experiment data, gene information, gene annotations and mutant information. In this version, we updated these datasets and improved the navigation and the visual display of the data views. In addition, a web service API now enables users to retrieve the data in various formats with other tools, seamlessly.

Prediction of nitrogen metabolism-related genes in Anabaena by kernel-based network analysis.

Prediction of molecular interaction networks from large-scale datasets in genomics and other omics experiments is an important task in terms of both developing bioinformatics methods and solving biological problems. We have applied a kernel-based network inference method for extracting functionally related genes to the response of nitrogen deprivation in cyanobacteria Anabaena sp. PCC 7120 integrating three heterogeneous datasets: microarray data, phylogenetic profiles, and gene orders on the chromosome. We obtained 1348 predicted genes that are somehow related to known genes in the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. While this dataset contained previously known genes related to the nitrogen deprivation condition, it also contained additional genes. Thus, we attempted to select any relevant genes using the constraints of Pfam domains and NtcA-binding sites. We found candidates of nitrogen metabolism-related genes, which are depicted as extensions of existing KEGG pathways. The prediction of functional relationships between proteins rather than functions of individual proteins will thus assist the discovery from the large-scale datasets.

Group 3 sigma factor gene, sigJ, a key regulator of desiccation tolerance, regulates the synthesis of extracellular polysaccharide in cyanobacterium Anabaena sp. strain PCC 7120.

The changes in the expression of sigma factor genes during dehydration in terrestrial Nostoc HK-01 and aquatic Anabaena PCC 7120 were determined. The expression of the sigJ gene in terrestrial Nostoc HK-01, which is homologous to sigJ (alr0277) in aquatic Anabaena PCC 7120, was significantly induced in the mid-stage of dehydration. We constructed a higher-expressing transformant of the sigJ gene (HE0277) in Anabaena PCC 7120, and the transformant acquired desiccation tolerance. The results of Anabaena oligonucleotide microarray experiments showed that a comparatively large number of genes relating to polysaccharide biosynthesis were upregulated in the HE0277 cells. The extracellular polysaccharide released into the culture medium of the HE0277 cells was as much as 3.2-fold more than that released by the control cells. This strongly suggests that the group 3 sigma factor gene sigJ is fundamental and conducive to desiccation tolerance in these cyanobacteria.

Identification of endocrine disruptor biodegradation by integration of structure-activity relationship with pathway analysis.

We present a SAR method that can predict estrogen-like endocrine disrupting chemical (EDC) activity as well as key biodegradation steps for detoxification. This method is based on a recent graph-mining algorithm developed by Kudo et al., which generates a set of descriptors from all potent chemical fragments (including rings). This method is novel in that it achieves chemical diversity in the training data set by sampling another data set of larger diversity. The model achieved an 83% accuracy prediction rate, and identified 1291 EDC candidates from the KEGG database. From this set of candidate compounds, bisphenol A was chosen for assay validation and biodegradation pathway analysis. Results showed that bisphenol A exhibited estrogen-like activity and was degraded in three distinct reactions. The prediction model provided information on the mechanism of the ligand-target binding, such as key functional groups involved. We focused on the enzyme commission number, which is useful for analyses of biodegradation pathways. Results identified oxygenases, ether hydrolases, and carbon-halide lyases as being important in the biodegradation pathway. This combined approach provided new information regarding the biodegradation of EDCs, and can potentially be extended to applications with transcriptomic, proteomic, and metabolomic data to provide a quick screen of biological activity and biodegradation pathway(s).

Complete genomic structure of the bloom-forming toxic cyanobacterium Microcystis aeruginosa NIES-843.

The nucleotide sequence of the complete genome of a cyanobacterium, Microcystis aeruginosa NIES-843, was determined. The genome of M. aeruginosa is a single, circular chromosome of 5,842,795 base pairs (bp) in length, with an average GC content of 42.3%. The chromosome comprises 6312 putative protein-encoding genes, two sets of rRNA genes, 42 tRNA genes representing 41 tRNA species, and genes for tmRNA, the B subunit of RNase P, SRP RNA, and 6Sa RNA. Forty-five percent of the putative protein-encoding sequences showed sequence similarity to genes of known function, 32% were similar to hypothetical genes, and the remaining 23% had no apparent similarity to reported genes. A total of 688 kb of the genome, equivalent to 11.8% of the entire genome, were composed of both insertion sequences and miniature inverted-repeat transposable elements. This is indicative of a plasticity of the M. aeruginosa genome, through a mechanism that involves homologous recombination mediated by repetitive DNA elements. In addition to known gene clusters related to the synthesis of microcystin and cyanopeptolin, novel gene clusters that may be involved in the synthesis and modification of toxic small polypeptides were identified. Compared with other cyanobacteria, a relatively small number of genes for two component systems and a large number of genes for restriction-modification systems were notable characteristics of the M. aeruginosa genome.

A phytochrome-like protein AphC triggers the cAMP signaling induced by far-red light in the cyanobacterium Anabaena sp. strain PCC7120.

In the filamentous, nitrogen-fixing cyanobacterium Anabaena sp. PCC7120, red light (630 nm) decreased, whereas far-red light (720 nm) increased cellular adenosine 3',5'-cyclic monophosphate (cAMP) content. To find a red and far-red light photoreceptor that triggers the cAMP signal cascade, we disrupted 10 open reading frame having putative chromophore-binding GAF domains. The response of the cellular cAMP concentration to red and far-red light in each open reading frame disruptant was determined. It was found that only the mutant of the gene all2699 failed to respond to far-red light. The open reading frame named as aphC encoded a protein with 920 amino acids including GAF domains similar to those involved in Cph2, a photoreceptor of Synechocystis sp. PCC6803. To determine which adenylate cyclase (AC) is responsible for far-red light signal, we disrupted all AC genes and found that CyaC was the candidate. The enzymatic activity of CyaC might be controlled by a far-red light photoreceptor through the phosphotransfer reaction. The site-specific mutant of the Asp59 residue of the receiver (R1) domain of CyaC lost its light-response capability. It was suggested that the far-red light signal was received by AphC and then transferred to the N-terminal response regulator domain of CyaC. Then its catalytic activity was stimulated, which increased the cellular cAMP concentration and drove the subsequent signal transduction cascade.

Molecular evolution of PAS domain-containing proteins of filamentous cyanobacteria through domain shuffling and domain duplication.

When the entire genome of a filamentous heterocyst-forming N2-fixing cyanobacterium, Anabaena sp. PCC 7120 (Anabaena) was determined in 2001, a large number of PAS domains were detected in signal-transducing proteins. The draft genome sequence is also available for the cyanobacterium, Nostoc punctiforme strain ATCC 29133 (Nostoc), that is closely related to Anabaena. In this study, we extracted all PAS domains from the Nostoc genome sequence and analyzed them together with those of Anabaena. Clustering analysis of all the PAS domains gave many specific pairings, indicative of evolutionary conservations. Ortholog analysis of PAS-containing proteins showed composite multidomain architecture in some cases of conserved domains and domains of disagreement between the two species. Further inspection of the domains of disagreement allowed us to trace them back in evolution. Thus, multidomain proteins could have been generated by duplication or shuffling in these cyanobacteria. The conserved PAS domains in the orthologous proteins were analyzed by structural fitting to the known PAS domains. We detected several subclasses with unique sequence features, which will be the target of experimental analysis.

Photoresponsive cAMP signal transduction in cyanobacteria.

The molecular mechanism of cAMP-mediated signal transduction from light reception to the physiological response via regulation of gene expression in cyanobacteria is described based on our recent works. Cyanobacteria are known as the organisms that acquired oxygen-evolving, higher plant type photosynthesis. We have found that the cellular cAMP level in the filamentous cyanobacteria Anabaena was oppositely regulated by red and far-red light, i.e., decreasing and increasing, respectively, suggesting that a phytochrome-like red/far-red photoreversible pigment regulates the activity of a certain adenylate cyclase. On the other hand, in the unicellular cyanobacterium Synechocystis cellular cAMP content was increased by blue light irradiation, which led to stimulation of cell motility. The cAMP signaling pathway is known to play an important role in the regulation of various biological activities by altering enzyme activities or controlling gene expression levels in both prokaryotes and eukaryotes. We have isolated genes for adenylate cyclases and cAMP receptor proteins and characterized their molecular properties. Disruption of these genes resulted in the loss of cell motility. It is concluded that the light signal was transmitted by cAMP signal cascade in cyanobacteria.