title: Inhibitory effects and oxidative target site of dibutyl phthalate on Karenia brevis.
abstract: The inhibitory action and possible damage mechanism of dibutyl phthalate (DBP) on the red tide algae Karenia brevis were investigated. The results showed that the algae experienced oxidative stress after exposure to 5mgL(-1) DBP. Malondialdehyde (MDA) peaked after 72h, with a value approximately 2.3 times higher than that observed for untreated cells. The superoxide dismutase (SOD) and catalase (CAT) activities significantly increased as an adaptive reaction after 48h. DBP induced the overproduction of reactive oxygen species (ROS), the OH concentration showed a peak of 33UmL(-1) at 48h, and the highest H2O2 content was approximately 250nmol/10(7) cells at 72h; these latter two values were 2.5 and 4.4 times higher than observed for the control, respectively. TEM images showed that a number of small vacuoles or apical tubers were commonly found around the cell membrane, and the membrane structure was ultimately disintegrated. Further experiments were carried out to locate the original ROS production sites following DBP exposure. The activity of CuZn-SOD (a mainly cytosolic isoform, with some also found in chloroplasts) under DBP exposure was approximately 2.5 times higher than the control, whereas the Mn-SOD (mitochondrial isoform) activity was significantly inhibited. No significant difference was observed in the activity of Fe-SOD (chloroplastic isoform). In addition, dicumarol (an inhibitor of the electron transport chain in the plasma membrane) stimulated DBP-induced ROS production, whereas rotenone (an inhibitor of the mitochondria electron transport chain complex I) decreased DBP-induced ROS production. These results suggested that mitochondria could be the main target sites for DBP attack.
authors.affiliation: Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China. Electronic address: lifengmin@ouc.edu.cn.
authors.forename: Feng-min
authors.initials: FM
authors.lastname: Li
authors.affiliation: Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
authors.forename: Miao
authors.initials: M
authors.lastname: Wu
authors.affiliation: Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Yao
authors.affiliation: School of Environment and Natural Resources, Renmin University of China, Beijing 100872, China. Electronic address: zhengxiang7825@sina.com.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
authors.forename: Zhen-yu
authors.initials: ZY
authors.lastname: Wang
authors.affiliation: Key Lab of Marine Environmental Science and Ecology, Ministry of Education, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, USA. Electronic address: bx@pssci.umass.edu.
authors.forename: Bao-shan
authors.initials: BS
authors.lastname: Xing
mesh_terms: D003993:Dibutyl Phthalate / Q000378:metabolism*; D004141:Dinoflagellida / Q000187:drug effects*; D057097:Harmful Algal Bloom / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2
chemical_list: D003993:Dibutyl Phthalate; D006861:Hydrogen Peroxide; D008315:Malondialdehyde; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2
keywords: DBP; Karenia brevis; Oxidative stress; Toxicity mechanism