Fig. 1

Graphic representation of CRISPR-cas loci in R. anatipestifer strains. The black blocks represent CRISPR loci. AT-rich leader sequences (light grey blocks) are located upstream of CRISPR1. There are three cas genes (cas1, cas2 and cas9) which are closed to CRISPR1, shown as white boxed arrows. Upstream of cas9, there is a 16 nt-long anti-repeat sequence, which might be considered as a portion of the sequence that encodes for a putative tracrRNA (dark grey block). The distance between CRISPR1 and CRISPR2 is long and varies from strain to strain, thus the sequence between the two loci is omitted and is represented by a double-slash