ISfinder () is a dedicated database for bacterial insertion sequences (ISs). It has superseded the Stanford reference center. One of its functions is to assign IS names and to provide a focal point for a coherent nomenclature. It is also the repository for ISs. Each new IS is indexed together with information such as its DNA sequence and open reading frames or potential coding sequences, the sequence of the ends of the element and target sites, its origin and distribution together with a bibliography where available. Another objective is to continuously monitor ISs to provide updated comprehensive groupings or families and to provide some insight into their phylogenies. The site also contains extensive background information on ISs and transposons in general. Online tools are gradually being added. At present an online Blast facility against the entire bank is available. But additional features will include alignment capability, PsiBLAST and HMM profiles. ISfinder also includes a section on bacterial genomes and is involved in annotating the IS content of these genomes. Finally, this database is currently recommended by several microbiology journals for registration of new IS elements before their publication.

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Insertion sequences (ISs) are among the smallest and simplest autonomous transposable elements. ISfinder (http://www-is.biotoul.fr/) is a dedicated IS database which assigns names to individual ISs to maintain a coherent nomenclature, an IS repository including >3000 individual ISs from both bacteria and archaea and provides a basis for IS classification. Each IS is indexed in ISfinder with various associated pieces of information (the complete nucleotide sequence, the sequence of the ends and target sites, potential open reading frames, strain of origin, distribution in other strains and available bibliography) and classified into a group or family to provide some insight into its phylogeny. ISfinder also includes extensive background information on ISs and transposons in general. Online tools are gradually being added. At present, it is difficult to visualize the global distribution of ISs in a given bacterial genome. Such information would facilitate understanding of the impact of these small transposable elements on shaping their host genome. Here we describe ISbrowser (http://www-genome.biotoul.fr/ISbrowser.php), an extension to the ISfinder platform and a tool which permits visualization of the position, orientation and distribution of complete and partial ISs in individual prokaryotic genomes.