Assessment of Antenna Heterogeneity and the Activity of the Oxygen-Evolving Complex of Photosystem II Using Mathematical Methods

Photosystem II is one of the main pigment–protein complexes of photosynthesis, which is highly sensitive to adverse environmental factors. The heterogeneity of photosystem II properties is necessary for the resistance of autotrophic organisms to stress factors. The assessment of photosystem II heterogeneity can be used in environmental monitoring for the rapid detection of environmental pollution. A comprehensive approach to the assessment of photosystem II heterogeneity is proposed; it is based on a mathematical analysis of the shape of the chlorophyll a fluorescence induction curve of samples treated with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea using a mathematical model and JIP test parameters. Fluorescence induction curves obtained for treated samples of Chlorella, Scenedesmus, Ankistrodesmus, Pleurochloris, and Stichococcus cell cultures were analyzed that grew in light with an intensity of 8 and 16 W/m^–2. For all cases, the ratio of reaction centers with different antenna sizes (alpha and beta centers) was estimated and the proportion of active and inactive oxygen-evolving complexes was determined.