Summary: For metabolite annotation in metabolomics, variations in the registered states of compounds (charged molecules and multiple components, such as salts) and their redundancy among compound databases could be the cause of misannotations and hamper immediate recognition of the uniqueness of metabolites while searching by mass values measured using mass spectrometry. We developed a search system named UC2 (Unique Connectivity of Uncharged Compounds), where compounds are tentatively neutralized into uncharged states and stored on the basis of their unique connectivity of atoms after removing their stereochemical information using the first block in the hash of the IUPAC International Chemical Identifier, by which false-positive hits are remarkably reduced, both charged and uncharged compounds are properly searched in a single query and records having a unique connectivity are compiled in a single search result. Availability and implementation: The UC2 search tool is available free of charge as a REST web service (http://webs2.kazusa.or.jp/mfsearcher) and a Java-based GUI tool. Contact: [email protected]. Supplementary information: Supplementary data are available at Bioinformatics online.

SUMMARY: High-accuracy mass values detected by high-resolution mass spectrometry analysis enable prediction of elemental compositions, and thus are used for metabolite annotations in metabolomic studies. Here, we report an application of a relational database to significantly improve the rate of elemental composition predictions. By searching a database of pre-calculated elemental compositions with fixed kinds and numbers of atoms, the approach eliminates redundant evaluations of the same formula that occur in repeated calculations with other tools. When our approach is compared with HR2, which is one of the fastest tools available, our database search times were at least 109 times shorter than those of HR2. When a solid-state drive (SSD) was applied, the search time was 488 times shorter at 5 ppm mass tolerance and 1833 times at 0.1 ppm. Even if the search by HR2 was performed with 8 threads in a high-spec Windows 7 PC, the database search times were at least 26 and 115 times shorter without and with the SSD. These improvements were enhanced in a low spec Windows XP PC. We constructed a web service 'MFSearcher' to query the database in a RESTful manner. AVAILABILITY AND IMPLEMENTATION: Available for free at http://webs2.kazusa.or.jp/mfsearcher. The web service is implemented in Java, MySQL, Apache and Tomcat, with all major browsers supported. CONTACT: [email protected] SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

UNLABELLED: Using a large dataset (10 022 assays) obtained from public plant microarray databases, we developed the CoP database for associating co-expressed gene modules with biological information such as gene ontology terms and, if available, metabolic pathway names. The Confeito algorithm developed previously in our laboratory, which is suitable to calculate the interconnectivity between genes in co-expressed gene network, was applied to extract co-expressed gene modules. The database includes the gene modules for Arabidopsis thaliana (thale cress) and seven crops, Glycine max (soybean), Hordeum vulgare (barley), Oryza sativa (rice), Populus trichocarpa (poplar), Triticum aestivum (wheat), Vitis vinifera (grape) and Zea mays (maize). AVAILABILITY: The CoP database is available at: http://webs2.kazusa.or.jp/kagiana/cop0911/.