Phages LLS and MD8 contain many Chi sites, which are concentrated near the right end. Dots are placed at the positions of Chi along the phage genome with equal vertical spacing reflecting their numerical order and showing a high concentration near the right end (vertical dashed line). Red dots are Chi sites in the orientation to activate RecBCD entering the DNA from the right end, as in bacteriophage λ (Kobayashi et al. 1982). (A) E. coli phage LLS. Note that the active Chi sites (5′-GCTGGTGG-3′ on the top strand) are about seven times more abundant than the inactive ones (20 vs. three). (B) P. aeruginosa phage MD8 (Evseev et al. 2021). Note that it has 32 Pseudomonas “Chi” sites (5′-GCTGGCGC-3′) in the presumably active orientation but none in the opposite orientation. For additional P. aeruginosa phages related to MD8, see Supplemental Fig. S5.