title: Singlet oxygen production in Chlamydomonas reinhardtii under heat stress.
abstract: In the current study, singlet oxygen formation by lipid peroxidation induced by heat stress (40 °C) was studied in vivo in unicellular green alga Chlamydomonas reinhardtii. Primary and secondary oxidation products of lipid peroxidation, hydroperoxide and malondialdehyde, were generated under heat stress as detected using swallow-tailed perylene derivative fluorescence monitored by confocal laser scanning microscopy and high performance liquid chromatography, respectively. Lipid peroxidation was initiated by enzymatic reaction as inhibition of lipoxygenase by catechol and caffeic acid prevented hydroperoxide formation. Ultra-weak photon emission showed formation of electronically excited species such as triplet excited carbonyl, which, upon transfer of excitation energy, leads to the formation of either singlet excited chlorophyll or singlet oxygen. Alternatively, singlet oxygen is formed by direct decomposition of hydroperoxide via Russell mechanisms. Formation of singlet oxygen was evidenced by the nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl detected by electron paramagnetic resonance spin-trapping spectroscopy and the imaging of green fluorescence of singlet oxygen sensor green detected by confocal laser scanning microscopy. Suppression of singlet oxygen formation by lipoxygenase inhibitors indicates that singlet oxygen may be formed via enzymatic lipid peroxidation initiated by lipoxygenase.
authors.affiliation: Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Ankush
authors.initials: A
authors.lastname: Prasad
authors.affiliation: Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Ursula
authors.initials: U
authors.lastname: Ferretti
authors.affiliation: Department of Botany, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Michaela
authors.initials: M
authors.lastname: Sedlářová
authors.affiliation: Department of Biophysics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71 Olomouc, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Pospíšil
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000378:metabolism*; D018869:Heat-Shock Response / Q000502:physiology*; D015227:Lipid Peroxidation / Q000502:physiology*; D008084:Lipoxygenase / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D026082:Singlet Oxygen / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D026082:Singlet Oxygen; D008315:Malondialdehyde; D008084:Lipoxygenase
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