Phytotoxic activity of diclofenac: evaluation using a model green alga Chlamydomonas reinhardtii with atrazine as a reference substance

Monika Majewska , Darya Harshkova , Monika Guściora , Anna Aksmann

Abstract

Human activities have caused increasing inputs of pharmaceuticals to the environment and diclofenac (DF) is one of the most commonly detected in freshwater systems. The aim of this study was to determine the impact of DF on a freshwater green alga as a non-target organism. For DF toxicity evaluation, its effects on a model organism Chlamydomonas reinhardtii were compared with effects caused by the herbicide atrazine (AT). EC50 values were about 135 mg/L for DF and 78 mg/L for AT, respectively. Both toxicants enhanced H2O2 production by the cells (144% and 178% of control for AT and DF, respectively) and stimulated catalase activity (≈200% of control). Activity of ascorbate peroxidase was elevated in AT-cells but not in DF-treated cells. DF did not influence dark respiration of the cells, whereas AT inhibited this process by about 50% compared to the control. Both toxicants caused photosynthesis inhibition. Analysis of parameters of chlorophyll a fluorescence in vivo showed diminishment of a performance index (PI) in both DF- and AT-treated cells (≈50% of control), but the reasons for the changes detected were different. AT diminished the efficiency of electron transport between PS II and PS I without significant inhibition of PS II or PS I reaction centers (RCs). In contrast to AT, DF seemed to influence directly PS II RCs. The fraction of active PS II RCs was lowered in DF-treated cells, but energy flux per active RC increased. Our study indicates that DF phytotoxicity results mainly from photosynthesis inhibition due to “silencing” of a fraction of PS II RCs.
Author Monika Majewska (FB / DPPB)
Monika Majewska,,
- Department of Plant Physiology and Biotechnology
, Darya Harshkova (FB / DPPB)
Darya Harshkova,,
- Department of Plant Physiology and Biotechnology
, Monika Guściora (FB)
Monika Guściora,,
- Faculty of Biology
, Anna Aksmann (FB / DPPB)
Anna Aksmann,,
- Department of Plant Physiology and Biotechnology
Journal seriesChemosphere, ISSN 0045-6535, (A 35 pkt)
Issue year2018
Vol209
Pages989-997
Publication size in sheets0.5
Keywords in Englishdiclofenac, atrazine, phytotoxicity, Chlamydomonas, chlorophyll fluorescence in vivo, oxidative stress
DOIDOI:10.1016/j.chemosphere.2018.06.156
URL https://doi.org/10.1016/j.chemosphere.2018.06.156
Languageen angielski
Score (nominal)35
ScoreMinisterial score = 35.0, 10-09-2018, ArticleFromJournal
Ministerial score (2013-2016) = 35.0, 10-09-2018, ArticleFromJournal
Publication indicators WoS Impact Factor: 2016 = 4.208 (2) - 2016=4.506 (5)
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