Fig. 5.

Dose-response analysis of iridoptin-induced apoptosis in budworm and boll weevil cells. (A) Budworm cells (CF) were treated with dilutions of iridoptin starting at 20 μg/ml (final concentration) and incubated at 28°C for 24 h. Cells were observed for apoptotic blebs with a phase-contrast microscope. Percent blebbing was determined from approximately 250 cells per field. Linear regression line and R² value were generated using Microsoft Excel 2003. The linear regression line was generated with the following equation: y = 24x + 75, where x is the log of final iridoptin concentration in μg/ml and y is the percentage of cell population with blebs. The R² value for the fitted line was 0.95. The highest dilution of toxin-produced blebbing in 50% of the cell population was approximately 0.1 μg/ml. (B) Boll weevil (AG) cells. The line was generated by the following equation: y = 17.5x + 55, where x is the log of final iridoptin concentration in μg/ml and y is the percentage of cell population with blebs. The R² value for the fitted line was 0.94. The final concentration of iridoptin required to induce blebbing in 50% of the cell population was 0.5 μg/ml. Assays for both cell lines were performed in triplicate.