title: Ameliorative role of nitric oxide on H2O2 toxicity to a chlorophycean alga Scenedesmus obliquus.
abstract: A concentration-dependent toxicity of hydrogen peroxide (H(2)O(2)) was observed on growth yield, chlorophyll a content and chlorophyll fluorescence characteristics of the green microalga Scenedesmus obliquus under laboratory batch culture conditions. The addition of sodium nitroprusside, a nitric oxide (NO) donor, in combination with H(2)O(2) prevented chlorophyll losses, and the inhibition level of growth yield, maximum quantum yield of photosystem II (PSII) and the light-adapted quantum yield of PSII were significantly reduced. The antioxidant compounds, penicillamine and thiourea also reduced the damage caused by H(2)O(2) exposure. The protective actions of sodium nitroprusside were, however, arrested in cultures where sodium nitroprusside was supplemented in combination with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), a specific scavenger of NO. The NO(3)(-)-grown Scenedesmus depicted less sensitivity to H(2)O(2) toxicity with respect to the quantum yields of PSII as compared to its NH(4)(1)-grown counterpart. The role of NO in providing protection against H(2)O(2) toxicity to the processes under study was discussed.
authors.affiliation: Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur 721 302, India. nm@agfe.iitkgp.ernet.in
authors.forename: Nirupama
authors.initials: N
authors.lastname: Mallick
authors.forename: Friedrich H
authors.initials: FH
authors.lastname: Mohn
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Soeder
authors.forename: Johan U
authors.initials: JU
authors.lastname: Grobbelaar
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002734:Chlorophyll / Q000096:biosynthesis; D000077194:Chlorophyll A; D000460:Chlorophyta / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000633:toxicity*; D007093:Imidazoles; D045342:Light-Harvesting Protein Complexes; D009569:Nitric Oxide / Q000502:physiology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010396:Penicillamine / Q000494:pharmacology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D045332:Photosystem II Protein Complex; D013890:Thiourea / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D007093:Imidazoles; D045342:Light-Harvesting Protein Complexes; D020030:Nitric Oxide Donors; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D009599:Nitroprusside; C079391:2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D010396:Penicillamine; D013890:Thiourea; D000077194:Chlorophyll A