Effects of some rare elements on nicotine content of the tobacco plant

Fifty-four rare elements were tested for their effects on the nicotine level of tobacco (Nicotiana tabacum L.) plants grown in solution culture. Be, Cu, Pd, Pt, and Sm definitely increased nicotine yield (over 25%), whereas Bi, Co, Ho, Pb, Ni, Rb, Ag, Tl, Sn, U. V. and Zr definitely decreased nicotine yield. Cs, Er, Li, Rh, Ru, Se, Sr, Ti, and Yb possibly increased (less than 25%) nicotine yield, whereas As, Ce, Cr, Dy, Gd, I, Mo, Nd, Re, Ta, and Th possibly decreased nicotine yield. Other elements including Al, Ge, Au, Hf, In, Ir, La, Lu, Hg, Os, Pr, Sc, Te, Tb, Tm, W, and Zn showed no significant effects.     

The Effect of Age and Gender on 59 Trace-Element Contents in Human Rib Bone Investigated by Inductively Coupled Plasma Mass Spectrometry

The effect of age and gender on 59 trace-element contents in rib bone of 80 apparently healthy 15–55-year-old women (n?=?38) and men (n?=?42) was investigated by inductively coupled plasma mass spectrometry. Mean values (M?±?SΕΜ) for the mass fraction (milligrams per kilogram, on dry-weight basis) of Ba, Bi, Cd, Ce, Cu, Dy, Er, Gd, La, Li, Mn, Mo, Nd, Pb, Pr, Rb, Sm, Sr, Tb, Tl, U, Yb, and Zn for both female and male taken together were: Ba 2.5?±?0.2, Bi 0.015?±?0.002, Cd 0.044?±?0.005, Ce 0.029?±?0.002, Cu 1.05?±?0.06, Dy 0.0020?±?0.0003, Er 0.0011?±?0.0002, Gd 0.0015?±?0.0001, La 0.020?±?0.002, Li 0.040?±?0.002, Mn 0.354?±?0.004, Mo 0.052?±?0.006, Nd 0.011?±?0.001, Pb 2.24?±?0.14, Pr 0.0032?±?0.0004, Rb 1.51?±?0.06, Sm 0.0014?±?0.0001, Sr 291?±?20, Tb 0.00041?±?0.00005, Tl 0.00050?±?0.00003, U 0.0013?±?0.0001, Yb 0.00072?±?0.00007, and Zn 92.8?±?1.5, respectively. The upper limit of mean contents of Ag, Al, B, Be, Br, Cr, Cs, Hg, Ho, Lu, Ni, Sb, Te, Th, Ti, Tm, and Y were: Ag?≤?0.011, Al?≤?7.2, B?≤?0.65, Be?≤?0.0032, Br?≤?3.9, Cr?≤?0.25, Cs?≤?0.0077, Hg?≤?0.018, Ho?≤?0.00053, Lu?≤?0.00024, Ni?≤?1.05, Sb?≤?0.0096, Te?≤?0.0057, Th?≤?0.0030, Ti?≤?2.8, Tm?≤?0.00006, and Y?≤?0.0047, respectively. In all bone samples, the contents of As, Au, Co, Eu, Ga, Hf, Ir, Nb, Pd, Pt, Re, Rh, Sc, Se, Sn, Ta, V, W, and Zr were under detection limits. The Ce, Dy, Er, Gd, La, Nd, Pr, Sm, Tb, and Yb contents increase with age. Higher Sr mass fraction is typical of female rib as compared to those in male bone.     

Determining the geographic origin of the brown planthopper,Nilaparvata lugens,using trace element content

Abstract A chemometric study using pattern recognition technology was carried out to characterize the geographic origins of the brown planthopper, Nilaparvata lugens. The concentrations of 23 trace elements (Mn, Mo, Cd, Ce, V, Th, Cs, Be, Tl, Fe, Nd, Pr, Se, Tm, Lu, Eu, Ho, Br, Dy, Gd, U, Sm and Er) in 53 samples from seven regions in southern China were determined using inductively coupled plasma mass spectrometry. The data obtained were successively evaluated using a multivariate statistical approach, namely, linear discriminant analysis, which allowed classification and discrimination of the N. lugens samples from Fuqing, Shaoguan, Hepu, Yongfu, Hengnan, Wan‐an and Yongkang with high accuracy and a clear separation among the seven regions. The results show that pattern identification on the basis of trace elements in the bodies of N. lugens is feasible for determining the geographic origins of individuals.     

混合样品代表地衣元素积累的平均水平——来自元素含量不同的两种地衣的证据

地衣是大气元素沉降的良好监测生物,其元素积累能力具有物种间和个体间差异。地衣原位监测法常使用混合样品代表每个样点的地衣元素积累水平,但混合样品的代表性及其在不同地衣之间的差异尚需进一步研究。以电感耦合等离子体质谱法（inductively coupled plasma mass spectrometry,ICP-MS）测定了内蒙古多伦县的丽石黄衣Xanthoria elegans和皮果衣Dermatocarpon miniatum 52种元素的含量并比较了样点内变异和物种间差异。结果显示,丽石黄衣与相似生境中的地衣元素含量大致相似,证实了研究区域以沙尘沉降为主的大气沉降特点。两种地衣的元素排序基本一致,表明其元素来源相同。7种营养元素（Ca、K、Mo、P、Rb、S和Se）的含量在物种间差异不显著,与地衣的生理调节有关。Hg含量的物种间差异不显著,可能与Hg的挥发性有关。皮果衣中44种元素（Al、As、B、Ba、Be、Bi、Cd、Ce、Co、Cr、Cs、Cu、Dy、Er、Eu、Fe、Gd、Ge、Ho、La、Li、Lu、Mg、Mn、Na、Nb、Nd、Ni、Pb、Pr、Sb、Sc、Sm、Sr、Tb、Th、Ti、Tl、Tm、U、V、Y、Yb和Zn）的含量是丽石黄衣的1.32-2.05倍,表明皮果衣具有较高的、元素特异性的元素积累能力。样点内除Ca含量变异较大（CV>31%）之外,其他51种元素的含量样点内变异在皮果衣和丽石黄衣中均<27.5%,表明混合样品在两种地衣中均可较好地代表地衣元素积累的平均水平。     

Competitive inhibition and selectivity enhancement by Ca in the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, Hf) by carrot (Daucus carota cv. U.S. harumakigosun)

We investigated the uptake of inorganic elements (Be, Na, Mg, K, Ca, Sc, Mn, Co, Zn, Se, Rb, Sr, Y, Zr, Ce, Pm, Gd, and Hf) and the effect of Ca on their uptake in carrots (Daucus carota cv. U.S. harumakigosun) by the radioactive multitracer technique. The experimental results suggested that Na, Mg, K, and Rb competed for the functional groups outside the cells in roots with Ca but not for the transporter-binding sites on the plasma membrrane of the root cortex cells. In contrast, Y, Ce, Pm, and Gd competed with Ca for the transporters on the plasma membrane. The selectivity, which was defined as the value obtained by dividing the concentration ratio of an elemental pair, K/Na, Rb/Na, Be/Sr, and Mg/Sr, in the presence of 0.2 and 2 ppm Ca by that of the corresponding elemental pair in the absence of Ca in the solution was estimated. The selectivity of K and Rb in roots was increased in the presence of Ca. The selectivity of Be in roots was not affected, whereas the selectivity of Mg was increased by Ca. These observations suggest that the presence of Ca in the uptake solution enhances the selectivity in the uptake of metabolically important elements against unwanted elements.     

Plant uptake of major and minor mineral elements as influenced by soil acidity and liming

This study reports effects on soil solution chemistry and plant uptake of 55 elements (Ag, Al, As, B, Ba, Be, Bi, Br, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Gd, Ge, Hf, Hg, Ho, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, S, Sb, Sc, Se, Si, Sm, Sr, Tb, Th, Tl, U, V, W, Y, Yb, Zn, Zr) by raising the pH using addition of fine-grained precipitated calcium carbonate at 20 rates (yielding a soil solution pH range of 5.2 – 7.8) to A horizon samples of an acid Cambisol, cultivating a common grass (Agrostis capillaris L.) and determining the soil solution, root and shoot concentrations of these elements at the end of the experiment. For many of these elements, there is little or no previous information about concentrations in soil solutions, or in plant biomass, as related to soil pH/acidity or addition of calcium carbonate. Soil solutions were obtained by high speed centrifugation and ultrafiltration (0.2 m) of samples at 60% water-holding capacity. Concentrations of elements were determined by ICP-ES or (in most elements) ICP-MS, using isotopes specified. Soil solution pH, HCO₃ and organic C were also determined.Concentrations of elements in the biomass of A. capillaris were usually inversely related to soil solution pH. The most apparent (p<0.001) inverse, though often curvilinear, relationships between pH and concentrations in shoot biomass were measured for Ag, As, B, Ba, Eu, Ge, Li, Mn, Ni, P and Sr. Positive relationships (p<0.05) were only measured in Ca, Hg, Mg, Mo and S. For concentrations in root biomass, relationships were mostly, but not always, of the same sign and of a similar strength. Though soil solution pH and concentrations of elements were usually quite closely correlated, pH and/or HCO^– ₃ concentration more often accounted for a higher share of the variability in biomass concentration of elements than did soil solution concentration of the same element.     

Effects of rare earth elements on telomerase activity and apoptosis of human peripheral blood mononuclear cells

To study the effects of rare earth exposure on human telomerase and apoptosis of mononuclear cells from human peripheral blood (PBMNCs). The blood contents of 15 rare earth elements, including La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, were measured by inductively coupled plasma-mass spectrometry. Telomeric repeat amplification protocol assay and flow cytometer analysis were carried out to analyze the telomerase activity and apoptosis of PBMNCs, respectively. The total content of rare earth elements in the blood showed significant differences between the exposed group and the control group. The rare earth exposure increased the telomerase activity and the percentages of cells in the S-phase and the G₂/M phase in PBMNCs, but it had no effect on the apoptotic rate of PBMNCs. Under the exposure to lower concentrations of rare earth elements, the telomerase activity of PBMNCs in the exposed group was higher than that of the control group, and there was no effect on the apoptotic rate of PBMNCs, but promoted the diploid DNA replication and increased the percentages of G₂/M- and S-phase cells.     

Rare earth elements in soil and in soil-grown plants

Concentrations of the rare earth elements (REEs) La, Ce, Nd, Sm, Eu, Gd, Tb, Yb and Lu were determined in leaves of 6 plant species (Norway spruce, silver fir, maple, ivy, blackberry, and wood fern), and in pertinent soils and soil extracts, also taken from the same site. The distribution of the individual REEs in plants showed little or no agreement with that in the soil or the soil extracts. Ce had a negative anomaly with respect to the soil in all plants. The REE distribution patterns of fir and spruce were almost identical, but differed profoundly from that of the other species. In most cases, concentration ratios between species were a smooth function of the atomic number of the REE. Very similar results were obtained at 2 additional sites.     

Mass Fractions of 52 Trace Elements and Zinc/Trace Element Content Ratios in Intact Human Prostates Investigated by Inductively Coupled Plasma Mass Spectrometry

Contents of 52 trace elements in intact prostate of 64 apparently healthy 13?C60-year-old men (mean age 36.5?years) were investigated by inductively coupled plasma mass spectrometry. Mean values (M ± S????) for mass fraction (in milligrams per kilogram, on dry-weight basis) of trace elements were as follows: Ag 0.041?±?0.005, Al 36?±?4, Au 0.0039?±?0.0007, B 0.97?±?0.13, Be 0.00099?±?0.00006, Bi 0.021?±?0.008, Br 29?±?3, Cd 0.78?±?0.09, Ce 0.028?±?0.004, Co 0.035?±?0.003, Cs 0.034?±?0.003, Dy 0.0031?±?0.0005, Er 0.0018?±?0.0004, Gd 0.0030?±?0.0005, Hg 0.046?±?0.006, Ho 0.00056?±?0.00008, La 0.074?±?0.015, Li 0.040?±?0.004, Mn 1.53?±?0.09, Mo 0.30?±?0.03, Nb 0.0051?±?0.0009, Nd 0.013?±?0.002, Ni 4.3?±?0.7, Pb 1.8?±?0.4, Pr 0.0033?±?0.0004, Rb 15.9?±?0.6, Sb 0.040?±?0.005, Se 0.73?±?0.03, Sm 0.0027?±?0.0004, Sn 0.25?±?0.05, Tb 0.00043?±?0.00009, Th 0.0024?±?0.0005, Tl 0.0014?±?0.0001, Tm 0.00030?±?0.00006, U 0.0049?±?0.0014, Y 0.019?±?0.003, Yb 0.0015?±?0.0002, Zn 782?±?97, and Zr 0.044?±?0.009, respectively. The upper limit of mean contents of As, Cr, Eu, Ga, Hf, Ir, Lu, Pd, Pt, Re, Ta, and Ti were the following: As ??0.018, Cr ??0.64, Eu ??0.0006, Ga ??0.08, Hf ??0.02, Ir ??0.0004, Lu ??0.00028, Pd ??0.007, Pt ??0.0009, Re ??0.0015, Ta ??0.005, and Ti ??2.6. In all prostate samples, the content of Te was under detection limit (<0.003). Additionally, ratios of the Zn content to other trace element contents as well as correlations between Zn and trace elements were calculated. Our data indicate that the human prostate accumulates such trace elements as Al, Au, B, Br, Cd, Cr, Ga, Li, Mn, Ni, Pb, U, and Zn. No special relationship between Zn and other trace elements was found.     

Solubilization of the binding protein from Ehrlich ascites cells and erythrocytes to Pseudomonas aeruginosa cytotoxin.

The binding protein for pore-forming Pseudomonas aeruginosa cytotoxin was solubilized from Ehrlich ascites cell plasma membranes and rabbit and bovine erythrocyte ghosts using nonionic and zwittergent detergents. Analysis of solubilized plasma membranes from Ehrlich cells by a ligand-blot technique after separation by SDS-PAGE/electrophoretic transfer to nitrocellulose or affinity chromatography showed a protein of 70 kDa molecular mass, which binds to cytotoxin. The binding protein solubilized from rabbit erythrocyte ghosts showed a molecular mass of 50 kDa and that from bovine ghosts 55 kDa according to the former test. The binding proteins could be characterized as acidic. They contain a glycan moiety which is, however, not involved in the interaction of cytotoxin with the binding site.     

Comparative study of methods for determining lanthanide elements in biological materials by using NAA,HPLC postcolumn reaction,and ICP-MS

Biological Trace Element Research - Mice were injected intravenously with one of the following elements: Y, La, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, or Yb, at a dose of 25 mg/kg body wt. After 20 h,...     

Accumulation of rare earth elements in human bone within the lifespan

For the first time, the contents of rare earth elements (REEs) in a rib bone of a healthy human were determined. The mean value of the contents of Ce, Dy, Er, Gd, La, Nd, Pr, Sm, Tb, and Yb (10 elements out of 17 total REEs), as well as the upper limit of means for Ho, Lu, Tm, and Y (4 elements) were measured in the rib bone tissue of 38 females and 42 males (15 to 55 years old) using inductively coupled plasma mass spectrometry (ICP-MS). We found age-related accumulation of REEs in the bone tissue of healthy individuals who lived in a non-industrial region. It was calculated that during a lifespan the content of REEs in a skeleton of non-industrial region residents may increase by one to two orders of magnitude. Using our results as indicative normal values and published data we estimated relative Gd accumulation in the bone tissue of patients according to magnetic resonance imaging with contrast agent and La accumulation in the bone tissue of patients receiving hemodialysis after treatment with lanthanum carbonate as a phosphate binder. It was shown that after such procedures contents of Gd and La in the bone tissue of patients are two to three orders of magnitude higher than normal levels. In our opinion, REEs incorporation may affect bone quality and health similar to other potentially toxic trace metals. The impact of elevated REEs content on bone physiology, biochemistry and morphology requires further investigation.     

Morphology and proliferation of B16 melanoma cells in the presence of lanthanoid and Al3+ ions

The effects of trivalent metal ions such as lanthanoid (La , Ce, Nd , Sm , Gd , Er , Yb , Lu ) and Al ions on the morphological change and proliferation of B16 melanoma cells in culture are discussed. These metal ions induced morphological transformations and decreased growth rates at doses of 1 mM. B16 melanoma cells treated with La , Ce , Nd , Sm , and Gd showed polyhedrical spreading. Elongation of axones was dependent on the metal ions. B16 melanoma cells treated with Er , Yb , Lu , and Al showed a long slender shape. Growth rates of melanoma cells in the presence of 1 mM of metal ions (La , Ce , Nd , Sm , Gd , Yb , Al ) were significantly lower than that of control cells. Measurements of cell cycle indicated that the metal ions arrested the transitions from G /G to S state. © Rapid Science 1998     

Study on air pollution in Beijing’s major industrial areas using multielements in biomonitors and NAA techniques

Three kinds of plant leaves, Chinese white aspen, arborvitae, and pine needles, have been sampled from the Yanshan Oil refinery complex, the Capital Iron and Steel Factory, and Badachu, a control area in Beijing, as biomonitors for air-pollution studies. Each sample was divided into two parts, washed, and unwashed. Thirty-one trace elements (As, Au, Br, Ca, Cd, K, La, Lu, Mo, Na, Sb, Sm, U, W, Yb, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, Rb, Sc, Se, Sr, Ta, Tb, Th, and Zn) have been determined by using the relative and the K₀ methods of instrumental neutron activation analysis (NAA) techniques. The results indicated the following: (1) The concentration of trace elements in unwashed samples are much higher than these in washed samples; (2) the area around Capital Iron and Steel Factory is heavily polluted, and the Yanshan Oil refinery complex area is moderately polluted; (3) Chinese white aspen is a good biomonitor in particular seasons and pine needles are better than arborvitae for yearly monitoring; (4) elements As, Cd, Hg, Co, Rb, Sb, W, and Zn are highly absorbed by Chinese white aspen. Pine needles are sensitive for the absorption the elements Br, Cr, Cd, Fe, Sc, Cs and rare earth elements, but arborvitae is very sensitive for the absorption of Sr.     

Criticality of the Rare Earth Elements

Recent constraints on supplies of the rare earth elements (REEs) have led to concerns about their long‐term availability as well as the consequences that shortages would pose for modern technology. To assess this situation, we apply a comprehensive “criticality” methodology to the REE: lanthanum (La); cerium (Ce); praseodymium (Pr); neodymium (Nd); samarium (Sm); europium (Eu); gadolinium (Gd); terbium (Tb); dysprosium (Dy); holmium (Ho); erbium (Er); thulium (Tm); ytterbium (Yb); lutetium (Lu); and yttrium (Y). Assessments are made on national (U.S. and China) and global levels for the year 2008. Evaluations of each indicator are presented and the results plotted in “criticality space” on a 0 to 100 scale. Over the medium term (5 to 10 years), supply risk (SR) for all REEs is moderate with minimal variation (62.8 to 65.1). Over the long term (10 to 100 years), SR is low (42.1 to 49.2). Environmental implications scores, reflecting the economic allocation of environmental burdens, range from 4.2 for La to 34.4 for Lu. Eu, Er, and Dy have the highest vulnerability to supply restriction (VSR) at the global level (50.6, 49.2, and 47.4, respectively), whereas Sm has the lowest (15.1). This is mainly a reflection of their substitution potential. Similarly, at the national level for the United States and China, Eu and Sm have the highest and lowest VSR scores, respectively, although there are notable differences in scores among the REEs and between countries. Although China's export restrictions render REE supplies inadequate to meet demand at present, our analysis indicates a lower criticality for REEs over the longer term than for a number of other industrially used metals.     

Multivariate analysis of elements in chinese brake fern as determined using neutron activation analysis

Pytoremediaton of arsenic (As) contamination using Chinese brake fern (Pteris vittata L.), an As hyperaccumulator has proven potential because of its cost-effectiveness and environmental harmonies. Aiming to investigate the elemental correlation in Chinese brake fern, 20 elements (As, Br, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, Na, Nd, K, Rb, Se, Sm, Sr, Th, Yb and Zn) were measured in the fronds and roots of the fern by neutron activation analysis. The ferns were sampled from two sites with high geogenic As levels: Zimudang (ZMD) and Lanmuchang (LMC) in Guizhou Province, China. Multivariate statistic analysis was performed to explore the interrelationship between these elements, especially between As and other elements. As was found to be positively related to K, Na, La, and Sm in both the roots and the fronds, suggesting that these four elements might operate as synergies to As during uptake and transportation processes. Se was positively related to most of the other cations measured, except in the fronds of the fern at ZMD, where Br replaced Se as positively related to the other cations. The difference of As and Se in correlation with other cationic elements suggested that the two anionic elements play different roles in elemental uptake processes. Our findings of elemental correlation highlight the importance of the anioncation balance in Chinese brake fern.     

Study on binding of REEs with water-soluble polysaccharides in fern

The binding of rare earth elements (REEs) with water-soluble polysaccharides of nondeproteinization and deproteinization in the leaves of the fernDicranopteris dichotoma was studied by molecular activation analysis (MAA). Two cold-water-soluble polysaccharides (extracted by 75% ethanol and 90% ethanol, respectively) and one hot-water-soluble polysaccharide (extracted by 90% ethanol) were separated using biochemical separation techniques. The eight rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu) in these polysaccharides were determined by instrumental neutron activation analysis. Our new results showed that the REEs were bound firmly with the water-soluble polysaccharides in the plant, regardless of whether nondeproteinization or deproteinization was used. The molecular-weight (MW) measurement demonstrated that REEs were mainly bound with low-MW (10,000–20,000) polysaccharides.     

Assessment the Exposure Level of Rare Earth Elements in Workers Producing Cerium,Lanthanum Oxide Ultrafine and Nanoparticles

In order to assess occupational exposure level of 15 rare earth elements (REEs) and identify the associated influence, we used inductively coupled plasma mass spectrometry (ICP-MS) based on closed-vessel microwave-assisted wet digestion procedure to determinate the concentration of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu in urinary samples obtained from workers producing ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggest that La and Ce were the primary component, together accounting for 97 % of total REEs in workers. The urinary levels of La, and Ce among the workers (6.36, 15.32 μg.g^?1 creatinine, respectively) were significantly enriched compared to those levels measured in the control subjects (1.52, 4.04 μg.g^?1 creatinine, respectively) (p < 0.05). This study simultaneously identified the associated individual factors, the results indicate that the concentrations in over 5 years group (11.64 ± 10.93 for La, 27.83 ± 24.38 for Ce) were significantly elevated compared to 1–5 years group (2.58 ± 1.51 for La, 6.87 ± 3.90 for Ce) (p < 0.05). Compared the urinary levels of La and Ce at the separation and packaging locations (9.10 ± 9.51 for La, 22.29 ± 21.01 for Ce) with the other locations (2.85 ± 0.98 for La, 6.37 ± 2.12 for Ce), the results show urinary concentrations were significantly higher in workers at separation and packaging locations (p < 0.01). Inter-individual variation in levels of La and Ce in urine is the result of multi-factorial comprehensive action. Further researches should focus on the multiple factors contributing to the REEs levels of the occupationally exposed workers.     

Rare earth elements in forest-floor herbs as related to soil conditions and mineral nutrition

Mixtures of rare earth elements (REEs) in fertilizers are widely used in Chinese agriculture to improve crop nutrition. REE concentrations in wild-growing plants, especially herbs, are little known. This study describes differences in the concentrations and proportions of REEs in eight forest-floor herbaceous plants and relates these differences to soil and mineral nutrient conditions. REEs studied were yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Leaf concentrations of sum REEs differed more than one order of magnitude between species, being highest in Anemone nemorosa (10.1 nmol/g dry mass) and lowest in Convallaria majalis (0.66 nmol/g) from the same site. Leaf concentrations of all REEs correlated positively (p<0.001), as did sum REE with calcium (Ca) and strontium (Sr) concentrations (p<0.001). A negative relationship (r=−0.83, (p<0.001) was measured between phosphorus (P) concentrations and sum REE concentrations in leaves. However, the proportions of the single REEs in the REE sum differed among species. In A. nemorosa, 57% of the molar REE sum was taken by Y+La, and only 21% by Ce. The other extreme was Maianthemum bifolium, with 37% La+Y and 41% Ce. These two species had 2.7–3.0% of the REE sum as heavier lanthanides, compared to 4.1–5.2% in the six other species. No clear relationship between soil properties or REE contents and leaf REE concentrations was detected. For La, however, an overrepresentation in leaves prevailed throughout all species compared to soils, whereas particularly Nd, Sm, and Tb had a lower proportion in the leaves of all species than in their soils. Possible uptake mechanisms of REEs in plants are discussed.     

Effects of fifteen rare-earth metals on Ca2+ influx in tobacco cells

Effects of naturally existing rare-earth metals (REMs; atomic numbers, 39, 57-60, 62-71; Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu), added as chloride salts, on Ca2+ influx induced by two different stimuli, namely hypoosmotic shock and hydrogen peroxide, were examined in a suspension-cultured transgenic cell line of BY-2 tobacco cells expressing aequorin, a Ca(2+)-sensitive luminescent protein in cytosol. Most REM salts used here showed inhibitory effect against Ca2+ influx. Especially NdCl3, SmCl3, EuCl3, GdCl3 and TbCl3 showed the most robust inhibitory action. In contrast, LuCl3, YbCl3, ErCl3 and YCl3 were shown to be poor inhibitors of Ca2+ influx. Since REMs tested here form a sequential range of ionic radii from 86.1 to 103.2 pm and the optimal range of ionic radii required for blocking the flux of Ca2+ was determined for each stimulus. The hydrogen peroxide-induced Ca2+ influx was optimally blocked by REMs with a broad range of ionic radii (93.8-101 pm) which is slightly smaller than or similar to that of Ca2+ (100 pm), while the hypoosmotically induced flux of Ca2+ was inhibited optimally by few REMs with a narrower range of relatively smaller ionic radii around that of Gd3+ (93.8 pm) a well known inhibitor of stretch-activated channels. Possible applications of such series of channel blockers in elucidation of plant signal transduction pathways are encouraged.