State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, China.
Ecotoxicol Environ Saf. 2012 Oct;84:104-11. doi: 10.1016/j.ecoenv.2012.06.028. Epub 2012 Jul 24.
Effects of arsenic on growth, pigments content, oxygen evolution and photosystem II (PSII) activity of Microcystis aeruginosa were investigated in the present study. Various concentrations of As(III) did not show significant effects on growth and total carotenoids content within 24 h of treatment. After 48 h of treatment, 10 mg L(-1) As(III) significantly inhibited the growth and synthesis of carotenoids of M. aeruginosa, while As(III) at concentrations ranging from 0 to 1 mg L(-1) showed no significant inhibition. Chlorophyll a synthesis, oxygen evolution and chlorophyll fluorescence were more sensitive to As(III) exposure than carotenoid synthesis and growth. Chlorophyll a content, fast fluorescence rise transients and fluorescence decay kinetics appeared to be affected after the cells were exposed to 1 and 10 mg L(-1) As(III) for more than 24 h. Treatment with 10 mg L(-1) As(III) for 24 h or longer led to flattening of the fluorescence transient and drastic decrease of amplitude of fast phase of QA- reoxidation kinetics. Exposure to As(III) mainly inhibited the quantum yield for primary photochemistry, density of reaction centers and photosynthesis performance index, and increased the dissipated energy. The decrease in amplitude of the fast and middle phases further revealed that once electron transfer from QA- to QB was inhibited by As(III), more QA- was reoxidized via S2(QAQB)- charge recombination. As(III) stress may result in an increased stability of the S2QB- and S2QA- recombination.
本研究探讨了砷对铜绿微囊藻生长、色素含量、氧气释放和光系统 II（PSII）活性的影响。在 24 小时的处理时间内，不同浓度的砷（III）对生长和总类胡萝卜素含量没有显著影响。处理 48 小时后，10mg/L 的砷（III）显著抑制铜绿微囊藻的生长和类胡萝卜素的合成，而浓度在 0 到 1mg/L 之间的砷（III）则没有表现出显著的抑制作用。与类胡萝卜素合成和生长相比，叶绿素 a 的合成、氧气释放和叶绿素荧光对砷（III）暴露更为敏感。叶绿素 a 含量、快速荧光上升瞬变和荧光衰减动力学在细胞暴露于 1 和 10mg/L 的砷（III）超过 24 小时后受到影响。用 10mg/L 的砷（III）处理 24 小时或更长时间会导致荧光瞬变变平，QA 再氧化动力学的快速相幅度急剧下降。砷（III）暴露主要抑制了初级光化学的量子产率、反应中心密度和光合作用性能指数，并增加了耗散能量。快速和中间相幅度的降低进一步表明，一旦 QA 到 QB 的电子转移被砷（III）抑制，更多的 QA-通过 S2(QAQB)-电荷复合而被重新氧化。砷（III）胁迫可能导致 S2QB-和 S2QA-复合的稳定性增加。
