title: Toxic effects of heavy metal terbium ion on the composition and functions of cell membrane in horseradish roots.
abstract: The environmental safety of rare earth elements (REEs), especially the toxic effect of REEs on plants, has attracted increasing attention. However, the cellular mechanism of this toxic effect remains largely unknown. Here, the toxic effects of heavy REE terbium ion [Tb(III)] on the cell membrane of horseradish roots were investigated by using electron microscope autoradiography (EMARG) and histochemical methods. The results indicated that Tb(III) was distributed in the extracellular and intracellular spaces of the roots after horseradish was treated with Tb(III). Moreover, the percentage contents of the unsaturated fatty acids in the membrane lipids, the current of the outward K(+) channel and the average diameter of membrane proteins in the roots of horseradish treated with Tb(III) were decreased; on the contrary, the percentage contents of the saturated fatty acids and malondialdehyde in the roots of horseradish treated with Tb(III) were increased. Furthermore, the contents of intracellular N, P, Mg and Fe in the roots of horseradish treated with Tb(III) were decreased, while the contents of intracellular K and Ca in the roots of horseradish treated with Tb(III) were increased. Finally, the effects of Tb(III) on horseradish roots were increased with increasing concentration or duration of Tb(III) treatment. In conclusion, after horseradish was treated with Tb(III), Tb(III) could enter the cells of horseradish roots and lead to the toxic effects on horseradish, which caused the oxidation of the unsaturated fatty acids in the membrane lipids, the changes in the membrane proteins (including the outward K(+) channel), the decrease in the membrane fluidity, and then the inhibition of the intracellular/extracellular-ion exchange in horseradish roots.
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
authors.forename: Lihong
authors.initials: L
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Food Science and Technology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China. Electronic address: qingzhou510@yahoo.com.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China. Electronic address: huangxiaohuanjnu@yahoo.com.
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Huang
mesh_terms: D031215:Armoracia / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects; D004785:Environmental Pollutants / Q000032:analysis / Q000633:toxicity*; D005227:Fatty Acids / Q000032:analysis; D008563:Membrane Lipids / Q000737:chemistry; D008565:Membrane Proteins / Q000032:analysis; D019216:Metals, Heavy / Q000032:analysis / Q000633:toxicity; D010940:Plant Proteins / Q000032:analysis; D018517:Plant Roots / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D013725:Terbium / Q000032:analysis / Q000633:toxicity*
chemical_list: D004785:Environmental Pollutants; D005227:Fatty Acids; D008563:Membrane Lipids; D008565:Membrane Proteins; D019216:Metals, Heavy; D010940:Plant Proteins; D013725:Terbium
keywords: Cell membrane; Fatty acid; Horseradish; Membrane lipid peroxidation; Terbium; Toxic effect