Unrooted distance matrix tree showing the phylogenetic relationships of known insertion elements belonging to the ISL3 family based on the corresponding transposases. The topology of the phylogenetic tree was evaluated by performing a bootstrap analysis with 1,000 replicates. The numbers at the nodes are bootstrap values based on 1,000 replicates. Scale bar = 0.1 Knuc. The accession numbers or source of information for the sequences used are as follows: IS1207, accession no. X96962; IS31831, accession no. D17429; ISBli3, http://www-is.biotoul.fr/is.html; ISPsp2, accession no. M57500; ISBli1, accession no. AF052055; IS13869, accession no. Z66534; IS1096, accession no. M76495; ISLdl1, accession no. AJ302652; IS1001, accession no. X66858; ISBma1, accession no. AF285635; ISRso15, accession no. NC_003295; ISPp2, accession no. U25434; ISPst2, accession no. AJ012352; IS1396, accession no. AF027768; IS466A, accession no. AB032065; IS469, accession no. AB032065; ISBlo6, accession no. NC_004307; ISAsp1, accession no. U13767; IS1181, accession no. L14544; IS1251, accession no. L34675; IS1167, accession no. M36180; IS1193, accession no. Y13713; IS1165, accession no. X62617; ISL3, accession no. X79114; IS651, accession no. NC_002570; and IS652, accession no. NC_002570.