Figure 6.

Time-dependent development of O₃-induced cell death in Bel-W3 and Bel-B tobacco cells. Cell death in Bel-W3 cells (A) and Bel-B cells (B) were induced by exposing the 10 ml of cell suspensions to the pulse of ozonized air lasting for 0, 2, 4, and 8 min. O₃-treated and pretreated cell suspensions (0.2 ml) were sampled and transferred to a 1.5 ml tube at the end of O₃ exposure. Cells were totally incubated for up to 24 h (O₃ exposure plus following incubation total the time indicated up to 24 h in each treatment). After occasional sampling as indicated in the figure (at 0, 0.25, 0.5, 0.75, 1.5, 3, 6, 12, 24 h), cells were stained with Evans blue for 1h. Three randomly chosen digital images of different portion of each sample under microscopes were acquired and stained cells were counted. Thus, each data point reflects the mean and S.E. (vertical bars, n = 3). Typical data from triplicate experiments. As controls, 10 ml of Bel-W3 cells and Bel-B cells were exposed to the pulse of O₃-free air for 0, 2, 4, and 8 min and incubated for 24 h. The levels of cell death measured after 24 h of static incubation were within 15–22% in Bel-W3 cells, and 24.5-28% in Bel-B cells.