title: Toxicological effects involved in risk assessment of rare earth lanthanum on roots of Vicia faba L. seedlings.
abstract: Combined chemical analyses and biological measurements were utilized to investigate potential toxicological effects and possible mechanisms involved in risk assessment of rare earth elements (REEs) on Vicia faba L. seedlings, which were hydroponically cultivated and exposed to various concentrations of lanthanum (La) for 15 days. The results showed that La contents in both the solution and roots increased with the increase of extraneous La, contributing to hormetic dose responses of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) and endoprotease (EP) isozymes activities, and HSP 70 production enhanced at low doses but suppressed at higher doses of La. These physiological responses constituted antioxidant and detoxification systems against La-induced oxidative stress. The elevated La levels also contributed to oxidatively modified proteins, which were most responsible for subsequent cell death and growth retardation of the roots. By combination of hormetic and traditional threshold dose levels, the threshold dose range was deduced to be 108-195 microg La/g dry weight in the roots, corresponding to 0.90-3.12 mg/L of soluble La in the culture solution. It suggests that persistent applications of REEs may lead to potential ecological risk in the environment.
authors.affiliation: School of Life Science, Huainan Normal University, Huainan 232001, China. chengrunw66@yahoo.com.cn
authors.forename: Chengrun
authors.initials: C
authors.lastname: Wang
authors.forename: Mei
authors.initials: M
authors.lastname: He
authors.forename: Wen
authors.initials: W
authors.lastname: Shi
authors.forename: Jessie
authors.initials: J
authors.lastname: Wong
authors.forename: Tao
authors.initials: T
authors.lastname: Cheng
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Wang
authors.forename: Lingling
authors.initials: L
authors.lastname: Hu
authors.forename: Fenfen
authors.initials: F
authors.lastname: Chen
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism; D015153:Blotting, Western; D002374:Catalase / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D059165:Hormesis / Q000187:drug effects; D007811:Lanthanum / Q000493:pharmacokinetics / Q000633:toxicity*; D009195:Peroxidase / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D018570:Risk Assessment / Q000379:methods; D013482:Superoxide Dismutase / Q000378:metabolism; D018675:Toxicity Tests; D031307:Vicia faba / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism
chemical_list: D018840:HSP70 Heat-Shock Proteins; D007811:Lanthanum; C121048:guaiacol peroxidase; D060387:Ascorbate Peroxidases; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase