Paul J. Janknegt

University of Groningen

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Anita G. J. Buma

University of Groningen

Willem H. van de Poll

University of Groningen

Ronald J. W. Visser

Wolters Kluwer (Netherlands)

J. W. Rijstenbil

Netherlands Institute of Ecology

E. Walter Helbling

Consejo Nacional de Investigaciones Científicas y Técnicas

Virginia E. Villafañe

Consejo Nacional de Investigaciones Científicas y Técnicas

Jan Roggeveld

University Medical Center Groningen

C. Marco de Graaff

University of Groningen

Tsanko Gechev

Center of Plant Systems Biology and Biotechnology

van Maria Leeuwe

Royal Netherlands Institute for Sea Research

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University of Groningen

Ecosystem Sciences

Royal Netherlands Institute for Sea Research

Rijksmuseum

Earth System Science Interdisciplinary Center

Stanford University

Foothill College

Netherlands Institute of Ecology

Wageningen University & Research

Consejo Nacional de Investigaciones Científicas y Técnicas

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Photoacclimation modulates excessive photosynthetically active and ultraviolet radiation effects in a temperate and an Antarctic marine diatom

Limnology and Oceanography (2006)

Willem H. van de Poll Anne‐Carlijn Alderkamp Paul J. Janknegt Jan Roggeveld Anita G. J. Buma

The influence of photoacclimation on the effects of excessive photosynthetically active (PAR; 400-700 nm) and ultraviolet (UVR; 280-400 nm) radiation was assessed for the marine diatoms Thalassiosira weissflogii (Grunow) Fryxell and Hasle and Thalassiosira antarctica (Comber). Low and high PAR acclimated cultures were subjected to simulated surface irradiance (SSI) that mimicked irradiance around noon, including UVR. PSII efficiency, xanthophyll conversion, superoxide dismutase (SOD) activity, carbohydrate buildup, and lipid peroxidation were investigated after 30 min SSI and during 120 min recovery in low irradiance. Furthermore, viability loss was measured during 4 h SSI. Prior to SSI, the diadino-diatoxanthin pool was increased in high irradiance acclimated cells, compared with cells grown under low irradiance. Thirty-minutes SSI caused a pronounced decline in PSII efficiency. This coincided with de-epoxidation of diadinoxanthin in high irradiance acclimated cells, which was completely reversed during recovery in low irradiance. De-epoxidation was lower for low irradiance acclimated cells, whereas PSII efficiency and carbohydrate buildup were lower during the recovery phase. Furthermore, clear UVR effects on PSII efficiency were observed in low irradiance but not in high irradiance acclimated cells. Although 30 min SSI did not increase cellular SOD activity and lipid peroxidation, prolonged (4 h) SSI caused viability loss in low irradiance acclimated cells, which was enhanced by UVR. Therefore, PAR and UVR-induced PSII inactivation and viability loss were reduced by high irradiance-mediated changes in light harvesting and the xanthophyll pigments. In addition to photoacclimation-modulated differences, minor sensitivity differences were found between species.

Photosynthetically active radiation

Photoprotection

Photoinhibition

10.4319/lo.2006.51.3.1239

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Citations (49)

OXIDATIVE STRESS RESPONSES IN THE MARINE ANTARCTIC DIATOM CHAETOCEROS BREVIS (BACILLARIOPHYCEAE) DURING PHOTOACCLIMATION¹

Journal of Phycology (2008)

Paul J. Janknegt Willem H. van de Poll Ronald J. W. Visser J. W. Rijstenbil Anita G. J. Buma

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.

Chaetoceros

Photoinhibition

10.1111/j.1529-8817.2008.00553.x

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Antioxidants, a radical solution?

Paul J. Janknegt

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Xanthophyll cycle activity and photosynthesis of Dunaliella tertiolecta (Chlorophyceae) and Thalassiosira weissflogii (Bacillariophyceae) during fluctuating solar radiation

Phycologia (2010)

Willem H. van de Poll Anita G. J. Buma Ronald J. W. Visser Paul J. Janknegt Virginia E. Villafañe

van de Poll W.H., Buma A.G.J., Visser R.J.W., Janknegt P.J., Villafañ V.E. and Helbling E.W. 2010. Xanthophyll cycle activity and photosynthesis of Dunaliella tertiolecta (Chlorophyceae) and Thalassiosira weissflogii (Bacillariophyceae) during fluctuating solar radiation. Phycologia 49: 249–259. DOI: 10.2216/08-83.1

Thalassiosira weissflogii

Chlorophyceae

Dunaliella

10.2216/ph-08-83.1

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Short-term antioxidative responses of 15 microalgae exposed to excessive irradiance including ultraviolet radiation

European Journal of Phycology (2009)

Paul J. Janknegt C. Marco de Graaff Willem H. van de Poll Ronald J. W. Visser J. W. Rijstenbil

Short-term photosensitivity and oxidative stress responses were compared for three groups of marine microalgae: Antarctic microalgae, temperate diatoms and temperate flagellates. In total, 15 low-light-acclimated species were exposed to simulated surface irradiance including ultraviolet radiation (SSI). Photosensitivity was assessed as the rate of recovery of Fv/Fm in the hours following SSI treatment. Before, during and after the SSI treatment, oxidative stress responses were assessed by following xanthophyll content and cycling, and activities of superoxide dismutase, ascorbate peroxidase and glutathione reductase, and glutathione redox status. When acclimated to low irradiance, antioxidant levels were not group specific. Superoxide dismutase activity was positively correlated with cell size, whereas in general, ascorbate peroxidase activity appeared to be lower and glutathione redox status appeared to be higher in the Antarctic than in the temperate species. After SSI exposure, the strong inhibition of PSII was followed by variable rates of recovery, although four species remained photosynthetically inactive. SSI tolerance appeared unrelated to geographic or taxonomic background, or to cell size. PSII recovery was enhanced in species with decreasing superoxide dismutase activity, glutathione redox status and increased xanthophyll cycle activity. We conclude that antioxidant responses are highly species specific and not related to the geographic or taxonomic background. Furthermore, xanthophyll cycling seems more important than antioxidants. Finally, it can be hypothesized that glutathione could function as a stress sensor and response regulator.

Glutathione reductase

Photoprotection

10.1080/09670260902943273

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Citations (49)

Excessive irradiance and antioxidant responses of an Antarctic marine diatom exposed to iron limitation and to dynamic irradiance

Journal of Photochemistry and Photobiology B Biology (2008)

Willem H. van de Poll Paul J. Janknegt Maria A. van Leeuwe Ronald J. W. Visser Anita G. J. Buma

APX

Glutathione reductase

Photosynthetic efficiency

10.1016/j.jphotobiol.2008.09.003

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Citations (37)

Antioxidants, a radical solution?: Antioxidant responses of marine microalgae to ultraviolet radiation

Paul J. Janknegt

Ultraviolet

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Citations (1)

Wavelength-dependent xanthophyll cycle activity in marine microalgae exposed to natural ultraviolet radiation

European Journal of Phycology (2009)

Anita G. J. Buma Ronald J. W. Visser Willem H. van de Poll Virginia E. Villafañe Paul J. Janknegt

The wavelength dependency of xanthophyll cycling in two marine microalgae (Thalassiosira weissflogii and Dunaliella tertiolecta) was studied by establishing biological weighting functions (BWFs) during exposure to natural ultraviolet radiation. High-(HL) and low-(LL) light-acclimated cultures of both species were exposed outdoors for up to 60 min under a series of UVR (280–400 nm) cut-off filters, after which the de-epoxidation state of xanthophyll cycle pigments, radiocarbon assimilation and photochemical quantum yield were measured. Exposures were repeated 4–8 times during the daily cycle to create exposure–response curves for each wavelength condition. UVR affected the three target processes significantly in both species and biological weights increased with decreasing wavelength, particularly in the UVBR region (280–315 nm). Minor wavelength dependency was observed between 315 and 360 nm. After BWF normalization to 300 nm, the LL cultures showed highly similar responses when comparing the three target processes, while the BWFs for the HL cultures differed significantly. The observed enhanced xanthophyll cycling activity in the UVR region implied that xanthophylls had an active role in diminishing UVR stress. However, this enhancement seems to be an indirect effect of damage within the dark reactions of photosynthesis. Hence, another vital target process further downstream in the photosynthetic process, possibly involved in the dark reactions, seems to be responsible for the high similarity in BWFs.

10.1080/09670260902971894

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Citations (22)

Inter- and Intraspecific Sod Responses to Irradiance in Antarctic Marine Microalgae

Phycologia (2005)

Paul J. Janknegt Willem H. van de Poll J. Roggeveld Tsanko Gechev Anita G. J. Buma

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Antioxidative Responses of Two Marine Microalgae During Acclimation to Static and Fluctuating Natural UV Radiation

Photochemistry and Photobiology (2009)

Paul J. Janknegt C. Marco de Graaff Willem H. van de Poll Ronald J. W. Visser E. Walter Helbling

Abstract Photoacclimation properties were investigated in two marine microalgae exposed to four ambient irradiance conditions: static photosynthetically active radiation (PAR: 400–700 nm), static PAR + UVR (280–700 nm), dynamic PAR and dynamic PAR + UVR. High light acclimated cultures of Thalassiosira weissflogii and Dunaliella tertiolecta were exposed outdoors for a maximum of 7 days. Dynamic irradiance was established by computer controlled vertical movement of 2 L bottles in a water filled basin. Immediate (<24 h), short‐term (1–3 days) and long‐term (4–7 days) photoacclimation was followed for antioxidants (superoxide dismutase, ascorbate peroxidase and glutathione cycling), growth and pigment pools. Changes in UVR sensitivity during photoacclimation were monitored by measuring UVR‐induced inhibition of carbon assimilation under standardized UV conditions using an indoor solar simulator. Both species showed immediate antioxidant responses due to their transfer to the outdoor conditions. Furthermore, upon outdoor exposure, carbon assimilation and growth rates were reduced in both species compared with initial conditions; however, these effects were most pronounced in D. tertiolecta . Outdoor UV exposure did not alter antioxidant levels when compared with PAR‐only controls in both species. In contrast, growth was significantly affected in the static UVR cultures, concurrent with significantly enhanced UVR resistance. We conclude that antioxidants play a minor role in the reinforcement of natural UVR resistance in T. weissflogii and D. tertiolecta .

Photosynthetically active radiation

Thalassiosira weissflogii

10.1111/j.1751-1097.2009.00603.x

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Citations (22)