Distribution of Lxc and Lxx IS elements across the complete nucleotide sequence of Lxx genome. Mapping of Lxc elements was based on similarity of flanking sequences. Elements located less than 20 kbp apart are shown on different levels for ease of visualization. Elements sharing the same family assignment and possibly the same target site of insertion are represented by the same symbol in Lxc and Lxx: IS1237 and ISLxx6 (green circles); ISLxc2 and ISLxx4 (red circles); ISLxc3 and ISLxx5 (blue circles). The remaining IS elements are marked as "X". Arrows indicate insertions of IS1237 copies within other IS elements. Black boxes indicate four genomic islands described for Lxx genome.