TY - JOUR
T1 - Okadaic acid inhibits cell growth and photosynthetic electron transport in the alga Dunaliella tertiolecta
AU - Perreault, François
AU - Matias, Marcelo Seleme
AU - Oukarroum, Abdallah
AU - Matias, William Gerson
AU - Popovic, Radovan
N1 - Funding Information:
This work was supported by research grants awarded to R. Popovic and W.G. Matias by the Fonds québécois de la recherche sur la nature et les technologies and the Conselho Nacional de Desenvolvimento Científico e Tecnológico , respectively. F. Perreault is supported by a Natural Sciences and Engineering Research Council Ph.D fellowship.
PY - 2012/1/1
Y1 - 2012/1/1
N2 - Okadaic acid (OA), which is produced by several dinoflagellate species, is a phycotoxin known to induce a decrease of biomass production in phytoplankton. However, the mechanisms of OA cytotoxicity are still unknown in microalgae. In this study, we exposed the green microalga Dunaliella tertiolecta to OA concentrations of 0.05 to 0.5μM in order to evaluate its effects on cell division, reactive oxygen species production and photosynthetic electron transport. After 72. h of treatment under continuous illumination, OA concentrations higher than 0.10μM decreased culture cell density, induced oxidative stress and inhibited photosystem II electron transport capacity. OA effect in D. tertiolecta was strongly light dependent since no oxidative stress was observed when D. tertiolecta was exposed to OA in the dark. In the absence of light, the effect of OA on culture cell density and photosystem II activity was also significantly reduced. Therefore, light appears to have a significant role in the toxicity of OA in microalgae. Our results indicate that the site of OA interaction on photosynthetic electron transport is likely to be at the level of the plastoquinone pool, which can lead to photo-oxidative stress when light absorbed by the light-harvesting complex of photosystem II cannot be dissipated via photochemical pathways. These findings allowed for a better understanding of the mechanisms of OA toxicity in microalgae.
AB - Okadaic acid (OA), which is produced by several dinoflagellate species, is a phycotoxin known to induce a decrease of biomass production in phytoplankton. However, the mechanisms of OA cytotoxicity are still unknown in microalgae. In this study, we exposed the green microalga Dunaliella tertiolecta to OA concentrations of 0.05 to 0.5μM in order to evaluate its effects on cell division, reactive oxygen species production and photosynthetic electron transport. After 72. h of treatment under continuous illumination, OA concentrations higher than 0.10μM decreased culture cell density, induced oxidative stress and inhibited photosystem II electron transport capacity. OA effect in D. tertiolecta was strongly light dependent since no oxidative stress was observed when D. tertiolecta was exposed to OA in the dark. In the absence of light, the effect of OA on culture cell density and photosystem II activity was also significantly reduced. Therefore, light appears to have a significant role in the toxicity of OA in microalgae. Our results indicate that the site of OA interaction on photosynthetic electron transport is likely to be at the level of the plastoquinone pool, which can lead to photo-oxidative stress when light absorbed by the light-harvesting complex of photosystem II cannot be dissipated via photochemical pathways. These findings allowed for a better understanding of the mechanisms of OA toxicity in microalgae.
KW - Cell growth
KW - Dunaliella tertiolecta
KW - Okadaic acid
KW - Oxidative stress
KW - Photosystem II
KW - Phycotoxin
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U2 - 10.1016/j.scitotenv.2011.10.045
DO - 10.1016/j.scitotenv.2011.10.045
M3 - Article
C2 - 22134032
AN - SCOPUS:84855532174
SN - 0048-9697
VL - 414
SP - 198
EP - 204
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -