| Abstract [eng] |
Oxidative stress is a fundamental process in biological systems, such as autotrophs. Although there is still a lack of comparative studies investigating the effects of stressors of different origins on parameters recorded by non-invasive spectroscopic and microscopic methods. In the present work, the effects of different origins of stressors such as light, H2O2, Mg-chlorophyllin and nanoparticles quantum dots (QDs) on photosynthetic and autofluorescence parameters of the green unicellular freshwater alga Scenedesmus sp. were studied. It was found that different stressors, independent from their nature, caused a decrease in photosynthetic efficiency (Y(II) and ETR). During the initial phase of stress, the excess absorbed energy was quenched by NPQ – antioxidative defence systems, but as the stress intensified, NPQ decreased, and energy was lost through unregulated pathways (Y(NO)). The initial changes in the photosynthetic parameters induced by QDs coincided with the changes induced by the oxidative stressors, so it is likely that these QDs also induced oxidative stress. In the dark QDs effect on studied parameters was due to stable QDs, and in light conditions additionally due to ROS generated by QDs. Although Mg-chlorophyllin, a natural photosensitizer, did not induce oxidative stress in Scenedesmus sp. algae, it was found that this compound could temporarily slow down the H2O2-induced decrease in photosynthetic efficiency and induce the absorbed energy to be quenched by cellular regulated pathways. It is also shown for the first time in this work that Mg-chlorophyllin can slow down the QD-induced changes in photosynthetic parameters. |
