Fig. 1.

A map of the regions of the T4 genome deleted in some of the den B mutations used for the construction of C-T4 strains. The mutation labeled Bruner’s “rIIH23” was used by Kiko etal. (1979), Rüger et al., (1979) and Marsh (1980). As discussed by Kutter et al. (1975), this deletion was confused with the original rIIH23. The C-T4 strain used here contains the rIINB5060 deletion. Carlson and Nicolaisen (1979) have used a strain carrying saΔ9 for restriction mapping