Fluorescence responsiveness of unicellular marine algae Dunaliella to stressors under laboratory conditions.

We examined the responsiveness of unicellular green alga Dunalliela tertiolecta to selected stressors employing confocal- and time-resolved imaging of endogenous fluorescence. Our aim was to monitor cell endogenous fluorescence changes under exposure to heavy metal Cd, acidification, as well as light by laser-induced photobleaching. The accumulation of Cd in algae cells was confirmed by the secondary ion mass spectroscopy technique. For the first time, custom-made computational techniques were employed to evaluate separately the fluorescence in the flagella vs. the body region. In the presence of Cd, we recorded increase in the green fluorescence in the flagella region in the form of opacities, without change in the fluorescence lifetimes, suggesting higher availability of the fluorescent molecules. Under acidification, we noted significant rise in the green fluorescence in the flagella region, but associated with longer fluorescence lifetimes, pointing to changes in the algae environment. Photobleaching experiments corroborated gathered observations. Obtained data support a differential responsiveness of the flagella vs. the body region to stressors and enable us to better understand the pathophysiological changes of algal cells in culture under stress conditions.