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EntrezThe Entrez Global Query Cross-Database Search System or retrieval system is a powerful federated search engine, or web portal that allows users to search many discrete health sciences databases at the National Center for Biotechnology Information (NCBI) website.The NCBI is a part of the National Library of Medicine (NLM), which is itself a department of the National Institutes of Health (NIH), which in turn is a part of the United States Department of Health and Human Services.The name "Entrez" (a greeting meaning "Come in!" in French) was chosen to reflect the spirit of welcoming the public to search the content available from the NLM.

Less flexible from SRS as do not allow customization with institutions preferred databases.Entrez Global Query is an integrated search and retrieval system that provides access to all databases simultaneously with a single query string and user interface. Entrez can efficiently retrieve related sequences, structures, and references. The Entrez system can provide views of gene and protein sequences and chromosome maps. Some textbooks are also available online through the Entrez system.It allow related articles in different databases to be linked to each other.

The Entrez front page provides, by default, access to the global query. All databases indexed by Entrez can be searched via a single query string, supporting boolean operators and search term tags to limit parts of the search statement to particular fields.Search results can be saved temporarily in a Clipboard. Users with a MyNCBI account can save queries indefinitely and also choose to have updates with new search results e-mailed for saved queries of most databases. It is widely used in the field of biotechnology to enhance the knowledge of students worldwide.It is a Life science search engine and used in Bioinformatics

Although the Entrez interface supports many databases, the Entrez wrapper supports only PubMed and Nucleotide. How the Entrez wrapper works

Many elements of the Entrez wrapper are common to all of the databases. These elements include: Connectivity with NCBI through the Web and the Entrez ESearch and EFetch utilities Mapping of hierarchical XML data into relational tables Joins between related tables through the XML wrapper technology

Entrez searches the following databases:PubMedPubMed CentralSite Search: NCBI web and FTP web sitesBooks: online booksOnline Mendelian Inheritance in Man (OMIM)Online Mendelian Inheritance in Animals (OMIA)Nucleotide: sequence database (GenBank)Protein: sequence databaseGenome: whole genome sequences and mappingStructure: three-dimensional macromolecular structuresTaxonomy: organisms in GenBank TaxonomySNP: single nucleotide polymorphismGene: gene-centered informationHomoloGene: eukaryotic homology groupsPubChem Compound: unique small molecule chemical structuresPubChem Substance: deposited chemical substance recordsGenome Project: genome project informationUniGene: gene-oriented clusters of transcript sequencesCDD: conserved protein domain databaseUniSTS: markers and mapping dataPopSet: population study data sets (epidemiology)GEO Profiles: expression and molecular abundance profilesGEO DataSets: experimental sets of GEO dataSequence read archive: high-throughput sequencing dataCancer Chromosomes: cytogenetic databasesPubChem BioAssay: bioactivity screens of chemical substancesGENSAT: gene expression atlas of mouse central nervous system[2]Probe: sequence-specific reagentsNLM CatalogAccessIn addition to using the search engine forms to query the data in Entrez, NCBI provides the Entrez Programming Utilities (eUtils) for more direct access to query results. Search fields vary by databasesSome fields are common to all Entrez databases, such as accession number (or in PubMed, UID), author name, text word, journal name, publication date, volume, etc.Other fields are present in most of the Entrez databases, such as title word, which appears in all except Structures. Some fields that are particularly useful for searching the nucleotide and protein sequence databases include:Organism Properties Sequence Length Feature Key (nucleotides only) Molecular Weight (proteins only)Properties field allows you to limit searches by a number of different record attributes, includingmolecule typeGenBank divisiongene locationsource databaseThe most commonly used properties are shown on the Limits page as check boxes or in pop-up menus (see Entrez Help doc for more details).To see a complete list of properties, browse the index of that field in the database of interest. For example, select the Entrez Nucleotide database, follow the link for Preview/Index in the grey bar beneath the search box, select Properties from the Search Field pop-up menu, and press the Index button. Use the Up and Down buttons to scroll through the index. Step 1:Select "Limits" optionEnter: cystic fibrosisSelect "Title Word" as search fieldPress "Go"Step 2:Select "Limits" optionEnter: humanSelect "Organism" as search fieldPress "GoThe Entrez Programming Utilities (E-utilities) are a set of eight server-side programs that provide a stable interface into the Entrez query and database system at the National Center for Biotechnology Information (NCBI). The E-utilities use a fixed URL syntax that translates a standard set of input parameters into the values necessary for various NCBI software components to search for and retrieve the requested data. The E-utilities are therefore the structured interface to the Entrez system, which currently includes 38 databases covering a variety of biomedical data, including nucleotide and protein sequences, gene records, three-dimensional molecular structures, and the biomedical literature. documentation provides a brief description of each field and its corresponding abbreviation. SRS ( Sequence Retrieval System) Developed initially in the early 1990s as an academic project at the European Molecular Biology Laboratory (EMBL)In 1997 moved to EBI in Cambridge. Development work was supported by various grants amongst others from the EMBnet.

SRS is a homogeneous interface to over 80 biological databases that had been developed at the European Bioinformatics Institute (EBI) at Hinxton, UK Or It is a network browser for databases in molecular biology or allows any flat file database to be indexed to any other. Or The Sequence Retrieval System (SRS) is the world's premier data integration, analysis and display tool for bioinformatics, genomics and related data

It is a powerful tool allowing the users to formulate queries across a range of different database types via a single interface.

the system has evolved into a commercial product and is currently sold under license as a stand-alone software product.

Computer Centre has recently set up the SRS on the BIOINFO server (http://bioinfo.hku.hk/srs) for supporting large-scale speedy access of the genetics sequence from HKU.

Latest Version of SRSWhile most of the other SRS servers around the world are still using the SRS version 6, we are pleased to inform our users that we have installed the latest SRS version 7 system on our BIOINFO server. The SRS system can provide speedy and efficient performance for the searching, query and linkage of sequences from the huge databases. SRS7 provides several enhancements in sequence parsing, sorting and logging, as well as supporting the XML database and EMBOSS applications.

New Genome Data LibrariesIn the meantime, there are a lot of new genome databanks installed in BIOINFO (with automatic update), for example, GenBank, Genpept, NCBI Reference Sequence, ENSEMBL, NRL3D, PFAM, PDB, IMGT, NCBI LocusLink, NCBI dbEST, NCBI dbGSS, NCBI dbSTS, KABATN, OMIM, PATHWAY, RHDB, UNIGENE, BLOCKS, DOMO, ENZYME, PRINTS, IPI, INTERPRO, DSSP, FSSP, HSSP, LCOMPOUND, LENZYME, etc. (detailed information of the databanks can be found at http://bioinfo.hku.hk/database). All these databanks have been integrated in the SRS and there are now around 80 genome data libraries available in the BIOINFO SRS. The web page listing all the databases contains a link to a description page about the database including the date on which it was last updated

Embedded Software toolsUsers can also enjoy using the genetics software embedded in SRS. One can directly launch several genetics software tools integrated in the SRS, such as BLAST, CLUSTALW, and most of the EMBOSS applications, after making their sequence queries or submitting their own sequences.Support ICARUSSRS supports programming with ICARUS (Interpreter of Commands And Recursive Syntax) which can be seen as a normal language interpreter like Perl or TCL, with the added capability of syntax specification. With reference to the Icarus User Guide, users can build their own customized programs to retrieve and manipulate customized structures of sequences from the BIOINFO databanks, as well as executing other different tools (such as BLAST, EMBOSS) inside the Icarus programs.

Online Help and TutorialSRS provides comprehensive online help on every page layout of the system, and there are also several online SRS reference guides accessible from the SRS interface. The SRS reference documents and step-by-step tutorials are available at the BIOINFO homepage (http://bioinfo.hku.hk/documents.html). Computer Centre will soon arrange SRS workshops for users to learn how to use the SRS.