Figure 1

Growth kinetics (A) and plating efficiency (B) of SAEC cells and SAEC-A0.5 cells in SAGM medium. Data are the mean of triplicates. Bars represent ± SD, P < 0.01. C. Colony numbers in soft-agar: 1 × 10³ cells in 1 mL 0.35% agarose were overlaid on a 0.7% agar base in a 24-well culture plate. Cultures were fed every three days, and colonies with >50 cells were scored after four weeks in cultures under a dissecting microscope. The experiment was carried out in triplicate. Bars represent ± SD. PALA-resistant colonies: Frequency determined at a concentration of 180 µM PALA that corresponds to nine times the LD₅₀ of SAEC-A0.5 (data not shown): data are pooled from three independent experiments (D). Bars represent ± SD. Micronuclei (MN) formation: cells were incubated with cytochalasin-B (3 µg mL/L) for 24 h. After a hypotonic shock in 0.075 M KCl, cells were stained with acridine orange and examined with a fluorescence microscope under UV light. Cells with MN were counted in three independent experiments involving 1000 cells. Bars represent ± SD, P < 0.01 (E). Micronuclei can be observed in representative images of SAEC and SAEC-A0.5 cells (F).