title: OXIDATIVE STRESS RESPONSES IN THE MARINE ANTARCTIC DIATOM CHAETOCEROS BREVIS (BACILLARIOPHYCEAE) DURING PHOTOACCLIMATION(1).
abstract: The enzyme superoxide dismutase (SOD) holds a key position in the microalgal antioxidant network. The present research focused on oxidative stress responses in the Antarctic diatom Chaetoceros brevis F. Schütt during transition to excess (including ultraviolet radiation [UVR]) and limiting irradiance conditions. Over a 4 d period, cellular responses of thiobarbituric acid reactive substances (TBARS, a general oxidative stress indicator), SOD activity, photosynthetic and xanthophyll cycle pigments, PSII efficiency, and growth were determined. In addition, oxidative responses were measured during a daily cycle. Changing irradiance conditions significantly affected growth rates of C. brevis. PSII efficiency decreased significantly during periodic excess irradiance and increased under low irradiance conditions. Transition to excess irradiance increased the ratio of xanthophyll to light-harvesting pigments, whereas the opposite was observed for cultures transferred to low irradiance. This acclimation process was completed after 2 d in the new irradiance environment. SOD activity increased significantly after the first day regardless of the new irradiance environment but returned to preexposure values on the fourth day. We hypothesize that SOD activity may be temporarily elevated in C. brevis after irradiance shifts, thereby reducing oxidative stress when photoacclimation is in progress.
authors.affiliation: Department of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the NetherlandsAE3 Consultancy, Fuchsialaan 8, 4401 HV, Yerseke, the NetherlandsDepartment of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the Netherlands.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Janknegt
authors.affiliation: Department of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the NetherlandsAE3 Consultancy, Fuchsialaan 8, 4401 HV, Yerseke, the NetherlandsDepartment of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the Netherlands.
authors.forename: Willem H
authors.initials: WH
authors.lastname: Van De Poll
authors.affiliation: Department of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the NetherlandsAE3 Consultancy, Fuchsialaan 8, 4401 HV, Yerseke, the NetherlandsDepartment of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the Netherlands.
authors.forename: Ronald J W
authors.initials: RJ
authors.lastname: Visser
authors.affiliation: Department of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the NetherlandsAE3 Consultancy, Fuchsialaan 8, 4401 HV, Yerseke, the NetherlandsDepartment of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the Netherlands.
authors.forename: Jan W
authors.initials: JW
authors.lastname: Rijstenbil
authors.affiliation: Department of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the NetherlandsAE3 Consultancy, Fuchsialaan 8, 4401 HV, Yerseke, the NetherlandsDepartment of Ocean Ecosystems, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750 AA Haren, the Netherlands.
authors.forename: Anita G J
authors.initials: AG
authors.lastname: Buma
keywords: Antarctic microalgae; UV radiation; malondialdehyde; oxidative stress; photoacclimation; photosystem II efficiency; superoxide dismutase; xanthophyll cycle