title: Induction of reactive oxygen species in marine phytoplankton under crude oil exposure.
abstract: Exposure of phytoplankton to the water-accommodated fraction of crude oil can elicit a number of stress responses, but the mechanisms that drive these responses are unclear. South Louisiana crude oil was selected to investigate its effects on population growth, chlorophyll a (Chl a) content, antioxidative defense, and lipid peroxidation, for the marine diatom, Ditylum brightwellii, and the dinoflagellate, Heterocapsa triquetra, in laboratory-based microcosm experiments. The transcript levels of several possible stress-responsive genes in D. brightwellii were also measured. The microalgae were exposed to crude oil for up to 96 h, and Chl a content, superoxide dismutase (SOD), the glutathione pool (GSH and GSSG), and lipid peroxidation content were analyzed. The cell growth of both phytoplankton species was inhibited with increasing crude oil concentrations. Crude oil exposure did not affect Chl a content significantly in cells. SOD activities showed similar responses in both species, being enhanced at 4- and 8-mg/L crude oil exposure. Only H. triquetra demonstrated enhanced activity in GSSG pool and lipid peroxidation at 8-mg/L crude oil exposure, suggesting that phytoplankton species have distinct physiological responses and tolerance levels to crude oil exposure. This study indicated the activation of reactive oxygen species (ROS) in phytoplankton under crude oil exposure; however, the progressive damage in cells is still unknown. Thus, ROS-related damage in nucleic acid, lipids, proteins, and DNA, due to crude oil exposure could be a worthwhile subject of study to better understand crude oil toxicity at the base of the food web.
authors.affiliation: Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, Baton Rouge, LA, USA. koray@ims.metu.edu.tr.|Department of Oceanography, Institute of Marine Sciences, Middle East Technical University, P.O.Box 28, 33731, Mersin, Erdemli, Turkey. koray@ims.metu.edu.tr.
authors.forename: Koray
authors.initials: K
authors.lastname: Ozhan
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: Sara
authors.initials: S
authors.lastname: Zahraeifard
authors.affiliation: Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: Aaron P
authors.initials: AP
authors.lastname: Smith
authors.affiliation: Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: Sibel
authors.initials: S
authors.lastname: Bargu
mesh_terms: D002734:Chlorophyll / Q000031:analogs & derivatives / Q000378:metabolism; D000077194:Chlorophyll A; D017377:Diatoms / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D004141:Dinoflagellida / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008145:Louisiana; D010578:Petroleum / Q000378:metabolism / Q000633:toxicity*; D010839:Phytoplankton / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010578:Petroleum; D017382:Reactive Oxygen Species; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; C085815:chlorophyll a'; D013482:Superoxide Dismutase; D005978:Glutathione; D000077194:Chlorophyll A
keywords: Crude oil; Phytoplankton; Reactive oxygen species; The deepwater horizon oil spill