Krona multilayered pie-charts of taxonomy in PULDB. The top-left corner includes web-browser classical features (text search area and buttons for browsing back and forward), and display features (depth of the taxonomy, font and chart sizes). The bottom-left corner displays the color scale that represents the number of PULs per species (averaged in ancestral nodes). The top-right corner indicates the selected taxonomic level and its relative information: the number of species (with a link to the listing), a link to PULDB to visualize all PULs for this taxon, a link to the NCBI taxonomy, etc. (A) Initial display of the most general taxonomic level, labeled ALL at the center, with a search for the character string ‘frigo’ highlighting the taxa having a positive result. (B) Display of the Sphingobacteriaceae level, resulting from a zoom-in by double-clicking on the ‘Sphingobacteriaceae’ area in (A) chart. Going back to (A) or intermediary levels is possible through the lineage links at the center.