Figure 3

Clonigenicity of UVC-treated Fhit-positive and -negative cells. (A) Dose–response clonigenicity for Fhit-positive and -negative A66 and E4 cells, respectively. MKN74E4 and A66 cells were seeded (3000 cells dish⁻¹) after no treatment, or 5, 10, 15 and 30 J m⁻² UVC. After 14 days, cells were fixed in methanol and stained with Giemsa. The values plotted are the averages from two separate experiments, containing three replica plates each. (B) MKN74E4 (Fhit negative) and MKN74A66 (Fhit positive) cells were exposed to 60 J m⁻² UVC, collected, counted and re-seeded (7500 per dish). After 18 days plates were fixed in 1 : 1 methanol : acetone, stained with Giemsa and colonies counted. E4 cells formed an average of 300 colonies/7500 cells and A66 an average of 30 colonies/7500 cells. The absence of Fhit confers an advantage in surviving the lethal dose of UVC. (C) Dose–response clonigenicity for Fhit +/+ and −/− mouse cells. The cells were seeded (3000 cells dish⁻¹) after no treatment or 5, 10, 15 or 30 J m⁻² UVC. After 14 days, the cells were fixed and stained. The averages from two separate experiments, containing three replica plates each, are shown. (D) Fhit +/+ and −/− cells were exposed to 60 J m⁻² UVC, collected, counted and re-seeded to dishes (5000 per dish). After 18 days, plates were fixed in 1 : 1 methanol : acetone, stained with Giemsa and colonies counted. Fhit −/− cells formed an average of 90 colonies/5000 cells and +/+ cells an average of 10 colonies/5000 cells.