Figure 1.

(A) A map of mthe-124 from M. thermoautotrophicus showing the locations of duplicated spacer-repeat units, or groups of units, labeled 1–5. Each triangle represents a spacer-repeat unit. Duplicated spacer-repeat units are shaded in gray. (B) Schematic representation of the six clusters which occur in the genome of S. solfataricus P2B (She et al. 2001). Each triangle represents a spacer-repeat unit. The colored triangles are coded to indicate the archaeal viruses, plasmids or chromosomes (S. solfataricus or A. fulgidus) that yield good matches with the spacer sequence. (C) A corresponding scheme is presented for three of the six clusters (ssol-95, ssol-32 and ssol-7) that are present in the chromosome of the closely related strain S. solfataricus P1 (Accession numbers: DQ831675, DQ831676 and DQ831677). Open triangles denote those spacer-repeat units that differ in sequence between the strains P1 and P2A. Abbreviation: del. indicates the two sites where deletion of several spacer-repeat units has occurred in strain P1 (or where insertions have occurred in strain P2B).