Simultaneous analysis of photosystem responses of Microcystis aeruginoga under chromium stress
Journal
Ecotoxicology and Environmental Safety
Journal Volume
88
Pages
163-168
Date Issued
2013
Author(s)
Abstract
Chromium (Cr) is a toxic metal that poses a great threat to aquatic ecosystems. Information is limited on coinstantaneous responses of photosystems I (PSI) and II (PSII) to Cr(VI) stress due to lack of instruments that can simultaneously measure PSI and PSII activities. In the present study, responses of quantum yields of energy conversion and electron transport rates of PSI and PSII in Microcystis aeruginosa cells to Cr(VI) stress were simultaneously analyzed by a DUAL-PAM-100 system. Quantum yield of cyclic electron flow (CEF) under Cr(VI) stress and its physiological role in alleviating toxicity of Cr(VI) were also analyzed. At 5mgL-1 Cr(VI), quantum yield and electron transport rate of PSII decreased significantly, and light-induced non-photochemical fluorescence quenching lost. Cr(VI) also inhibited efficiency of PSII to use energy under high light more than of PSI. PSII showed lower maximal electron transport rate and light adaptability than PSI. Electron transport rate of PSI was higher and decreased less than that of PSII, implying less sensitivity of PSI to high light and Cr(VI). Energy dissipation through non-light-induced non-photochemical fluorescence quenching increased with increasing Cr(VI) concentration. CEF was stimulated under Cr(VI) treatment and made a significant contribution to quantum yield and electron transport of PSI, which was essential for protection of PSI from stresses of Cr(VI) and high light. © 2012 Elsevier Inc.
Subjects
Cyclic electron flow; Electron transport rate; Freshwater algae; Heavy metals; Photosystem I; Photosystem II
Other Subjects
chromium; alga; aquatic ecosystem; chromium; concentration (composition); cyanobacterium; energy dissipation; heavy metal; article; concentration (parameters); controlled study; electron transport; energy conversion; light adaptation; Microcystis aeruginosa; nonhuman; nonphotochemical quenching; photosynthesis; photosystem I; photosystem II; phytotoxicity; plant cell; plant stress; quantum yield; Chlorophyll; Chromium; Electron Transport; Fluorescence; Light; Microcystis; Photosystem I Protein Complex; Photosystem II Protein Complex; Water Pollutants, Chemical; algae; Microcystis; Microcystis aeruginosa
Type
journal article