Changes in the Morphology and State of Pigments of the Alga Scenedesmus quadricauda under the Effect of Pesticides

Abstract

Changes in the morphology and state of the cytoplasm of the unicellular alga Scenedesmus quadricauda cells in vitro, as well as the conformation of the chloroplast pigment (carotenoid) under the effect of the pesticide clothianidin, were studied using laser interference microscopy and Raman spectroscopy. It was found that the effect of clothianidin on algae causes changes in the morphology and state of the cytoplasm of cells, as well as the conformation of carotenoids, which correlate with changes in intracellular pH. The action of the pesticide and the protonophore similarly changes the conformation of the carotenoid molecule in the chloroplast due to the fact that in the presence of clothianidin, direct electron transfer from \({\text{Q}}_{{\text{A}}}^{ - }\) to Q_B slows down, the proportion of photosystem II centers with an unoccupied Q_B binding site increases, and the rate of oxidation of \({\text{Q}}_{{\text{A}}}^{{}}\) decreases, probably because of a decrease in the binding rate of plastoquinone with the Q_B site in photosystem II.