title: Microcystin-LR induced oxidative stress and ultrastructural alterations in mesophyll cells of submerged macrophyte Vallisneria natans (Lour.) Hara.
abstract: Microcystins produced by cyanobacteria in the aquatic environment are a potential risk to aquatic plants. In the present study, the uptake of microcystin-LR (MC-LR) and related physiological and biochemical effects on Vallisneria natans (Lour.) Hara were investigated at concentrations of 0.1-25.0 μg L(-1). Results showed that O(2)(-) intensity was significantly induced at 1.0 μg L(-1) and reached a maximum level at 5.0 μg L(-1). Superoxide dismutase (SOD) and peroxidase (POD) were induced with increasing MC-LR concentrations as an antioxidant response. Catalase (CAT) was significantly induced while GSH/GSSG (reduced/oxidized glutathione) ratio was significantly reduced at 0.1 μg L(-1). The induction of glutathione S-transferase (GST) and inhibition of GSH revealed that GSH was involved in the detoxification of MC-LR in plants. Oxidative damage was evidenced by the significant increase of malondialdehyde content at 1.0 μg L(-1). A pigment pattern change and a series of significant ultrastructural alterations were also observed due to MC-LR exposure. The lowest non-effect concentration of MC-LR for V. natans at the subcellular and molecular level is around 0.5 μg L(-1). These results imply that even at relatively low MC-LR concentrations the aquatic plants may still suffer a negative ecological impact.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 22 Hankou Road, Nanjing 210093, PR China.
authors.forename: Jinlin
authors.initials: J
authors.lastname: Jiang
authors.forename: Xueyuan
authors.initials: X
authors.lastname: Gu
authors.forename: Rui
authors.initials: R
authors.lastname: Song
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Wang
authors.forename: Liuyan
authors.initials: L
authors.lastname: Yang
mesh_terms: D002273:Carcinogens; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D058503:Mesophyll Cells / Q000378:metabolism / Q000648:ultrastructure*; D052998:Microcystins / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects*; D009195:Peroxidase / Q000378:metabolism; D059828:Plant Cells; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D002273:Carcinogens; D052998:Microcystins; D009195:Peroxidase; D013482:Superoxide Dismutase; D005982:Glutathione Transferase; D005978:Glutathione