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Toxic effects and mechanism of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) on Lemna minor

Qiu, Nianwei, Wang, Renjun, Sun, Yuan, Wang, Xiushun, Jiang, Dacheng, Meng, Yuting, Zhou, Feng
Chemosphere 2018 v.193 pp. 711-719
Lemna minor, aquatic plants, chlorophyll, fronds, malate dehydrogenase, malondialdehyde, membrane permeability, peroxidase, photosynthesis, plasma membrane, protein content, superoxide anion, thylakoids, toxicity
To investigate the toxic effect and mechanism of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in aquatic plants, in vivo and in vitro exposure to BDE-47 were conducted. After 14-d exposure to 5–20 μg/L BDE-47, the growth of Lemna minor plants was significantly suppressed, and the chlorophyll and soluble protein contents in fronds markedly decreased. Accordingly, the photosynthetic efficiency (Fv/Fm, PI) decreased. When the thylakoid membranes isolated from healthy fronds was exposed to 5–20 mg/L BDE-47 directly in vitro for 1 h, the photosynthetic efficiency also decreased significantly. In both the in vitro (5–20 μg/L) and in vivo (5–20 mg/L) experiments, BDE-47 led to an increased plasma membrane permeability. Hence, we concluded that BDE-47 had a direct toxicity to photosynthetic membranes and plasma membranes. However, direct effects on the activities of peroxidase (POD), malate dehydrogenase (MDH) and nitroreductase (NR) were not observed by adding 5–20 mg/L BDE-47 into crude enzyme extracts. The malondialdehyde (MDA) and superoxide anion radical (O2−) contents in the BDE-47 treated fronds were higher than those in the control fronds, suggesting that L. minor can not effectively relieve reactive oxygen species (ROS). The data above indicates that BDE-47 is toxic to L. minor through acting directly on biomembranes, which induces the production of ROS and thus causes remarkable oxidative damage to cells.