FIG. 3.

Morphological classification of cells following loss of the EcoRI RM gene complex. E. coli strains AB1157 (rec⁺) and JC5519 (recB21 recC22) carrying pIK172 (pSC101Ts, EcoRI r⁺ m⁺, Ap^r) or pIK173 (its r⁻ version) were treated as described in the legend to Fig. 2. The cells were classified into four types by visual inspection. A cell was judged to be a filament when it was larger than twice the unit size of the r⁻ cell before the temperature shift. The presence or absence of nuclei means that DAPI staining was positive or negative, respectively. The number at the top of each bar is the number of cells examined. Data for cell types I to IV are shown from top to bottom for each bar.