2.5.2. Analysis of cell morphology by acridine orange/ethidium
bromide (AO/EB) fluorescence staining
Analysis of changes in cell morphology was evaluated using
acridine orange/ethidium bromide (AO/EB) fluorescence staining
according to the method described by Jimenez et al. (2008) with
slight modifications. Briefly 3
×
106 cells were plated into 24-well
tissue culture plates and incubated for 24 h in the absence or presence
of 10.0 g/ml extracts of P. watsonii. The cells were then
detached from the plate with a 1.0 ml accutase in PBS pH 7.4. The
cell pellet was obtained by centrifugation at 1000 rpm for 5 min and
resuspended in 25 l of PBS pH 7.4. To each sample, 1 l of AO/EB
solution (1 part of 100 g/ml of AO in PBS; 1 part of 100 g/ml of EB
in PBS) was added just prior to microscopic examination. The cell
suspension was placed on a 3-well teflon coated microscopic slide,
covered with a glass cover slip and was examined with a Nikon
Eclipse 80i microscope under fluorescence illumination using FITC,
Cy3 and DAPI filters. Images were analyzed by Nikon’s Imaging
Software, NIS-Elements.