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ABSTRACT: Abstract The release of nanoparticles (NPs) to the environment poses an increasing potential threat to biological systems. This study investigated the phytotoxicity and accumulation of copper oxide (CuO) NPs to Elsholtzia splendens (a Cu-tolerant plant) under hydroponic conditions. The 50 % effective concentration (EC(50)) of CuO NPs to E. splendens was about 480 mg/L, implying the tolerance of E. splendens to CuO NPs. The Cu content in the shoots treated with 1000 mg/L CuO NPs was much higher than those exposed to the comparable 0.5 mg/L soluble Cu and CuO bulk particles (BPs). CuO NPs-like deposits were found in the root cells and leaf cells. Cu K-edge X-ray absorption near-edge structure (XANES) analysis further revealed that the accumulated Cu species dominated as CuO NPs in the plant tissues. All these results suggested that CuO NPs can be absorbed by the roots and translocated to the shoots in E. splendens.
Nanotoxicology 01/2013; · 5.76 Impact Factor
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ABSTRACT: PurposeContamination of heavy metals in soil and its subsequent accumulation along the food chain is a potential risk to human health.
Cu speciation in soil–plant system, particularly on the availability to plant roots, has obtained great attention. X-ray absorption
near-edge structure spectroscopy (XANES) provides information about the bonding of Cu soil components at the molecular scale.
In paddy soils, changes of redox conditions led to microbially mediated sulfur transformation, thus affecting heavy metal
behavior. The objective of this work was to investigate how sulfur transformation in a paddy soil affected Cu biogeochemical
processes.
Materials and methodsThe Cu and sulfur species and their relationship in rice–soil system were investigated under flooded condition. The speciation
of sulfur and copper in rice rhizosphere and bulk soil was investigated using integrated approaches including sequential extraction
and XANES.
Results and discussionCu speciation exhibited some differences in rhizosphere and bulk soil of rice. In flooded paddy soil, most Cu in the rhizosphere
existed as Cu (II), whereas part of Cu transformed to Cu (I) in the bulk soil. Sulfur XANES showed the presence of multiple
both oxidized and reduced forms of sulfur in studied soil samples, with more oxidized sulfur in the rhizosphere than in the
bulk soil. Copper and sulfur speciation changed depending on redox conditions. Changes in redox potential and microbial action
shifted the sulfur oxidation and reduction reaction and affected the Cu speciation. Combined action of organisms maintained
Cu homeostasis through cation binding to bioactive molecules. With higher Eh in rice rhizosphere, transformation of sulfur
and organic compounds together contributed to more soluble and exchangeable Cu. Cu bond to sulfur containing groups and biomineralization
by microorganisms could be defenses against toxic copper.
ConclusionsOur findings implied that Cu existed mainly as Cu (II) in rice rhizophere and part of Cu transformed to Cu (I) in anoxic bulk
soil. With higher Eh in rice rhizosphere, transformation of sulfur and organic compounds together contributed to more soluble
and exchangeable Cu. Combined action of organisms maintained Cu homeostasis through cation binding to bioactive molecules.
Our results indicated the important role of sulfur in the transformation of Cu. Due to the complicated processes in soil,
future work dedicating to the role of microbes is needed.
KeywordsBulk soil-Copper-Rice rhizosphere-Speciation-Sulfur-XANES
Journal of Soils and Sediments 04/2012; 10(5):907-914. · 1.86 Impact Factor
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ABSTRACT: Phytolacca acinosa Roxb. is a Mn hyperaccumulating plant. In the present study, the chemical forms of Mn in the leaves of P. acinosa were investigated using chemical analyses and X-ray absorption spectroscopy (XAS). P. acinosa plants were grown hydroponically with 2mM Mn for 28days. About 80% of the Mn in the leaves of P. acinosa was found in the supernatant fraction after centrifugation at 20,000g for 45min. The supernatant fraction was then used to identify the chemical forms of Mn. Gel filtration analysis (Sephadex
G-10) showed that oxalate and Mn appeared in the same fraction of the supernatant and the molar ratio of oxalic acid to Mn
was 1.12, indicating that there was sufficient oxalic acid in P. acinosa leaves to complex Mn. XAS was employed to investigate the chemical species of Mn in leaves of P. acinosa. Results showed that Mn in leaves was bivalent and almost 90% of the total Mn was Mn-oxalate. The oxalate concentration in
the leaves of P. acinosa was not affected by increasing Mn concentration in the solution, suggesting that oxalate biosynthesis was not induced by
Mn.
Plant and Soil 04/2012; 318(1):197-204. · 2.73 Impact Factor
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ABSTRACT: The rhizosphere, enriched in organic matter, is the bottleneck of metal transfer in the soil–plant system. However, the transformation
of metal fractions in the rhizosphere and the mechanisms that are involved, notably the role of organic matter, are poorly
known. In this study, the solid-phase fractionation of lead (Pb) in the rhizosphere and non-rhizosphere soil of Elsholtzia splendens in a Pb-contaminated soil was investigated using a nine-step selective sequential extraction method in a pot experiment.
Compared to the non-rhizosphere soil, there were measurable increases in Pb-fulvic complexes, Pb-humic complexes, organic
Pb, and amorphous Pb but no significant changes in other forms of Pb in the rhizosphere soil. Pb-fulvic complexes and organic
Pb, increasing from 397 to 438mg kg−1 and 229 to 258mg kg−1, respectively, showed a stronger accumulating trend than Pb-humic complexes and amorphous Pb, with an increase from 15.9
to 17.3mg kg−1 and 6.04 to 7.80mg kg−1 respectively, in the rhizosphere soil relative to non rhizosphere soil. These results may be mainly due to the enrichment
of organic matter in the rhizosphere soil, resulting from root exudation and the enhanced turnover of microorganisms. The
accumulation of Pb-fulvic complexes in the rhizosphere soil increases the potential phytoavailable pool, thus likely facilitating
the phytoextraction of Pb in metal-contaminated soil.
Water Air and Soil Pollution 04/2012; 205(1):333-342. · 1.63 Impact Factor
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ABSTRACT: Elsholtzia splendens is a Cu-tolerant plant growing in copper mine areas in the south of China. In this study, X-ray absorption spectroscopy (XAS)
was used to investigate the Cu speciation and biotransformation in E. splendens with 300μM Cu treatment from 10days to 60days. The results showed that 300μM Cu was phytotoxic to E. spendens. The Cu K-edge X-ray absorption near edge structure (XANES) revealed that most copper in roots, stems and leaves exists as
divalent Cu. Cu speciation changed depending on the treatment time, but there was no unidirectional trend in roots, stems,
and leaves. The percentages of potential Cu ligands in all samples were estimated by fitting the XANES spectra with linear
combinations. Most Cu in roots, stems and leaves was bound with cell wall and histidine (His)-like ligands, while a minor
proportion of the Cu was bound to oxalate and glutathione-like ligands. The fitting results of Cu K-edge extended X-ray absorption
fine structure (EAXFS) showed that nitrogen/oxygen (N/O) ligands were dominant in roots, stems and leaves of the plant, while
S ligands were rare. All these results suggest that Cu bound by N/O ligands plays a key role in Cu detoxification of E. splendens, and a role for classical metal-detoxifying S ligands, such as metallothioneins and phytochelatins, in Cu detoxification
of E. splendens is not supported in the present study. Due to the phytotoxicity of 300μM Cu to E. splendens, the question of whether S ligands play a significant role in Cu detoxification in E. splendens exposed to lower levels of Cu should be further studied.
Plant and Soil 04/2012; 302(1):163-174. · 2.73 Impact Factor
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ABSTRACT: It has become apparent that the threat of an organic pollutant in soil is directly related to its bioavailable fraction and that the use of total contaminant concentrations as a measure of potential contaminant exposure to plants or soil organisms is inappropriate. In light of this, non-exhaustive extraction techniques are being investigated to assess their appropriateness in determining bioavailability. To find a suitable and rapid extraction method to predict phenanthrene bioavailability, multiple extraction techniques (i.e., mild hydroxypropyl-β-cyclodextrin (HPCD) and organic solvents extraction) were investigated in soil spiked to a range of phenanthrene levels (i.e., 1.12, 8.52, 73, 136, and 335 μg g( - 1) dry soil). The bioaccumulation of phenanthrene in earthworm (Eisenia fetida) was used as the reference system for bioavailability. Correlation results for phenanthrene suggested that mild HPCD extraction was a better method to predict bioavailability of phenanthrene in soil compared with organic solvents extraction. Aged (i.e., 150 days) and fresh (i.e., 0 day) soil samples were used to evaluate the extraction efficiency and the effect of soil contact time on the availability of phenanthrene. The percentage of phenanthrene accumulated by earthworms and percent recoveries by mild extractants changed significantly with aging time. Thus, aging significantly reduced the earthworm uptake and chemical extractability of phenanthrene. In general, among organic extractants, methanol showed recoveries comparable to those of mild HPCD for both aged and unaged soil matrices. Hence, this extractant can be suitable after HPCD to evaluate risk of contaminated soils.
Environmental Monitoring and Assessment 08/2011; 184(1):549-59. · 1.40 Impact Factor
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ABSTRACT: Photoreduction is a major obstacle for using the X-ray absorption near-edge structure (XANES) fingerprint to perform metal speciation at the molecular level in biological and environmental samples, especially for metalloproteins. In this study, soft X-ray induced photoreduction was observed in organic Cu(II) compounds during XANES measurements in a third-generation synchrotron source. Next Cu L(3)-edge, O K-edge, and C K-edge XANES spectroscopy, together with the scanning transmission X-ray microscopy (STXM), were used to probe the specific radiation damage processes of Cu acetate with similar local structures to Cu metalloproteins. Breakup of the Cu-Cu bond was hypothesized for the initial photoreduction of Cu acetate. The following radiation damage of Cu acetate produced CuO and an organic Cu(I) compound with a C═C bond, and the further photoreduction of the resulting CuO to Cu metal was also demonstrated. Our results indicated the importance of consideration of photoreduction during soft XANES measurements for the solid state compounds with high valence metals. Reducing the radiation dose to ~0.1 MGy effectively prevented the photoreduction of organic Cu(II) compounds during these measurements. This proposed radiation damage mechanism in Cu acetate may be generally useful in explaining the photoreduction process in Cu metalloproteins.
Analytical Chemistry 08/2011; 83(20):7856-62. · 5.86 Impact Factor
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ABSTRACT: A new mesophilic and chemolithoautotrophic sulfur oxidizing bacterium (SOB) strain HT1 was isolated from a rice rhizosphere soil polluted by Pb using thiosulfate as electron donor at pH 7.0. The 16S rRNA gene sequence showed that the new isolate was a sulfur oxidizing obligate chemolithotroph belonging to Gammaproteobacteria, Halothiobacillus and utilizing different reduced sulfur compounds (sulfide, elemental sulfur, thiosulfate and sulfite) as chemolithotrophic substrates. Strain HT1 was able to use CO 2 as a carbon source responsible for the reduction of nitrate to nitrite, which represented a halophilic SOB capable of growth within a broad salinity range of 0 to 3 M NaCl and a heavy-metals-tolerant SOB. HT1 was Gram negative, motile and was proposed as the type strain of a novel species of sulfur oxidizing bacteria. The soxB gene could not be detected in strain HT1 during thiosulfate oxidation. The metabolism pathway of HT1 was 'S4 intermediate' (S4I) pathway. Sulfur globules accumulated in HT1 were mainly S 8 .
AFRICAN JOURNAL OF BIOTECHNOLOGY 04/2011; 1020:4121-4126. · 0.57 Impact Factor
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ABSTRACT: Phytolacca americana L. (pokeweed) is a promising species for Cd phytoextraction with large biomass and fast growth rate. To further understand the mechanisms involved in Cd tolerance and detoxification, the present study investigated subcellular distribution and chemical forms of Cd in pokeweed. Subcellular fractionation of Cd-containing tissues indicated that both in root and leaves, the majority of the element was located in soluble fraction and cell walls. Meanwhile, Cd taken up by pokeweed existed in different chemical forms. Results showed that the greatest amount of Cd was found in the extraction of 80% ethanol in roots, followed by 1 M NaCl, d-H(2)O and 2% HAc, while in leaves and stems, most of the Cd was extracted by 1 M NaCl, and the subdominant amount of Cd was extracted by 80% ethanol. It could be suggested that Cd compartmentation with organo-ligands in vacuole or integrated with pectates and proteins in cell wall might be responsible for the adaptation of pokeweed to Cd stress.
Journal of hazardous materials 02/2011; 186(1):103-7. · 4.14 Impact Factor
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ABSTRACT: CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer-Emmett-Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L(-1) soluble copper or by 1.0 mg L(-1) CuO-NP that released only 0.16 mg L(-1) soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 mg L(-1) CuO-NP, but not in the comparable 0.2 mg L(-1) soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content.
Environmental pollution (Barking, Essex: 1987) 02/2011; 159(5):1277-82. · 3.43 Impact Factor
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ABSTRACT: The transformation of phosphorus (P) is a major factor of lake eutrophication, and phosphate releasing bacteria play an important role in the release process. Experiments were conducted to investigate P content and characterize phosphate solubilizing bacterial composition at the molecular level in a shallow eutrophic lake and a wetland. Results showed that P concentrations were relatively high and derived from agricultural runoff and domestic or industrial pollution. Enumeration and molecular identification of these strains indicated that these bacterial groups were abundant in the ecosystem and various kinds of bacteria participated in the phosphorus release process. Twelve phosphate solubilizing bacteria, including eight organic P-solubilizing bacteria (OPBs) and four inorganic P-solubilizing bacteria (IPBs), which belonged to three different families, were isolated and identified. Cupriavidus basilensis was found for the first time to have the ability to mineralize organic P (OP). Laboratory tests on P release ability revealed that IPBs were more effective at releasing P than OPBs. The most efficient IPB strain could accumulate over 170 mg·L-1 orthophosphate, while the equivalent OPB strain only liberated less than 4 mg·L-1 orthophosphate in liquid culture. The results obtained from this investigation should help clarify the roles of microorganisms in aquatic systems and the mechanisms of eutrophication.
Molecules 11/2010; 15(11):8518-33. · 2.39 Impact Factor
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ABSTRACT: There has been increasing concern in recent years about the concentration of lead (Pb) in tea. However, little research has been done to address questions concerning the distribution of Pb in different varieties of tea plant and the differences among tea plant varieties in their uptake and accumulation of Pb from the soil. Therefore the aim of this study was to investigate the accumulation of Pb in different tea plant varieties and the factors affecting Pb bioavailability.
Three patterns of Pb distribution could be observed in different plant parts among the eight tea varieties surveyed, as well as a linear relationship between the Pb concentration in fine roots and the exchangeable Pb fraction in the corresponding soil. The uptake of Pb by fine roots increased significantly as the soil pH decreased. The average ratios of Pb concentration in fine roots to those in young stems and young leaves were 5.18 and 31.80 respectively. In fine roots the Pb concentration varied from 22.7 to 61.6 mg kg(-1).
The results indicated that the uptake, transport and accumulation of Pb by tea plant organs were strongly governed by soil conditions and tea variety, thus providing tea producers with useful information on variety selection for the production of quality teas containing low levels of Pb.
Journal of the Science of Food and Agriculture 07/2010; 90(9):1501-7. · 1.44 Impact Factor
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ABSTRACT: To explore the copper uptake mechanisms by the Cu-tolerant plant Commelina communis, the contents of Cu and other metals (including Fe, Zn, and Mn) in roots were detected using atomic absorption spectrometer under transporter inhibitors, partial element deficiency, or Cu excess treatments, while distribution characters of Cu and other metals in root growth zones were investigated by synchrotron radiation X-ray fluorescence spectroscopy (SRXRF). Cu uptake was inhibited by the uncoupler DNP and P-type ATPase inhibitor Na(3)VO(4), not by the Ca(2+) ion channel inhibitor LaCl(3), suggesting that Cu could probably be assimilated actively by root and be related with P-type ATPase, but not through Ca(2+) ion channel. Fe or Zn deficiency could enhance Cu uptake, while 100 μM Cu inhibited Fe, Zn, and Mn accumulation in roots significantly. Metal distribution under 100 μM Cu treatment was investigated by SRXRF. High level of Cu was found in the root meristem, and higher Cu concentrations were observed in the vascular cylinder than those in the endodermis, further demonstrating the initiative Cu transport in the root of C. communis. Under excess Cu stress, most Fe was located in the epidermis, and Fe concentrations in the endodermis were higher than those in the vascular cylinder, suggesting Cu and Fe competition not only in the epidermal cells but also for the intercellular and intracellular transport in roots. Zn was present in the meristem and the vascular cylinder similar to Cu. Cu and Zn showed a similar pattern. Mn behaves as Zn does, but not like Fe.
Biological trace element research 05/2010; 141(1-3):294-304. · 1.92 Impact Factor
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ABSTRACT: To explore the differences of rhizo-bacterial diversity among different habits and the relationship between the quality of Fritillaria thunbergii and microbial diversity, the soil bacterial diversity was analyzed by denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) and the content of peimine and peiminine in F. thunbergii was detected by high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD). For the DGGE analysis, the genetic diversity based on Shannon index of rhizo-bacterial community was the highest in Nantong (NT), followed by Chunan (CA), Panan (PA) and Ningbo (NB). Furthermore, it was significantly higher in rhizosphere soil than in non-rhizosphere soil, which indicated that some kinds of bacteria related to the growth of F. thunbergii were accumulated in rhizoshpere. Bacterial diversity based on principal component analysis (PCA) showed significant differences among all samples obtained from different habits and are divided into three major taxa: NB, CA and PA. It was found that the highest content of peimine (0.1364%) and peiminine (0.0518%) in NT, while the lowest peimine in NB (0.0646%) and the lowest peiminine (0.0316%) in PA. Moreover, the rhizo-bacterial diversity was relatively high related to the alkaloid concentration of F. thunbergii.
Journal of Medicinal Plants Research. 04/2010; 4:465-470.
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ABSTRACT: Element fingerprints were deciphered for Fritillaria thunbergii from Chinese ten major fritillaria-producing regions for the purpose of examining differences in element composition with region of origin and identifying elements' importance to F. thunbergii. Analysis by inductively coupled plasma optical emission spectrometry allowed simultaneous determination of 18 elements in F. thunbergii (Al, B, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Na, Mn, Mo, S, Ni, P, Pb, and Zn), and patterns in element concentrations were deciphered by principle component analysis (PCA) and hierarchical cluster analysis (HCA). The element fingerprint was established which well reflected the element characteristics of F. thunbergii. Meanwhile, the ten regions were discriminated with 100% accuracy using HCA and PCA based on 18 of these elements. The element Mg, Ca, K, B, P, Mo, Na, Cd, Ni, and Al were viewed as the characteristic element of F. thunbergii, and the fingerprint of these elements could be used to distinguish the authenticity of F. thunbergii Miq.
Biological trace element research 02/2010; 135(1-3):304-13. · 1.92 Impact Factor
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ABSTRACT: BACKGROUND: Tea is an infusion made from dried leaves of tea (Camellia sinensis) and can be a good dietary source of essential trace metals for humans. Therefore, it is necessary to consider variations in element content of tea leaves among tea cultivars. Thus, elemental fingerprint techniques, based on elemental contents (Al, B, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, and Zn) determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and multivariate statistical analysis, have been used to differentiate eight tea cultivars.RESULTS: The ranges of element concentrations in leaves of the eight cultivars were in good agreement with those obtained in previous studies and the level of most elements in tea leaves was significantly different among cultivars. The classifications of eight tea cultivars were 100% accurate in total by principal component analysis (PCA), hierarchical cluster analysis (HCA), linear discriminant analysis (LDA), and back-propagation neural network (BPNN) analysis.CONCLUSION: Each cultivar presented a distinctive element fingerprint and the elements in tea leaves can be significant predictors in differentiating tea cultivars. Copyright © 2009 Society of Chemical Industry
Journal of the Science of Food and Agriculture 09/2009; 89(14):2350 - 2355. · 1.44 Impact Factor
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ABSTRACT: Elsholtzia splendens is generally considered as a Cu-tolerant and -accumulating plant species, and a candidate for phytoremediation of Cu-contaminated soils. To better understand the Cu tolerance/accumulation mechanisms in E. splendens, proteomic analysis was performed on E. splendens roots and leaves exposed to 100 muM CuSO(4) for 3 and 6 days. After 6 days of treatment, Cu accumulation in roots increased much more than that in leaves. SDS-PAGE analysis showed that the proteins changed more intensively in roots than did in leaves upon Cu stress. Two-dimensional gel electrophoresis (2-DE) and image analyses found that 45 protein spots were significantly changed in roots, but only six protein spots in leaves. The abundance of protein spots mostly showed temporal changes. MALDI-TOF MS and LTQ-ESI-MS/MS were used to identify the differently expressed protein spots. The identified root proteins were involved in various cellular processes such as signal transduction, regulation of transcription and translation, energy metabolism, regulation of redox homeostasis and cell defense. The leaf proteins were mainly degraded fragments of RuBisCo and antioxidative protein. The roles of these proteins in Cu tolerance/accumulation were discussed. The resulting differences in protein expression pattern suggested that redirection of root cellular metabolism and redox homeostasis might be important survival mechanisms of E. splendens upon Cu stress.
Plant Molecular Biology 08/2009; 71(3):251-63. · 4.15 Impact Factor
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ABSTRACT: Laser ablation coupled with inductively coupled plasma-mass spectrometry was used to find Cu and Zn concentration in surface tissue along a longitudinal developmental gradient with meristem, rapidly elongating tissue, and nongrowing tissue in a model system of seedling roots of Cucumis sativus L. (cucumber). Tissue metal accumulation was determined for roots of seedlings growing on cellulosic germination paper treated with nutrient solution (controls), and also treated with concentrations of Zn (40 ppm) and Cu (10 ppm) that reduced growth. Cu content of all roots is highest at the apex and falls sharply to lower values by 2 mm from the root tip. In contrast, at moderate Zn availability (0.07 ppm), Zn content rises from the apex to 2 mm then falls throughout the remainder of the growth zone. At high external Zn the spatial pattern resembles that of Cu. Cucumber root growth zones accumulate more of each metal with higher external availability. Metal deposition rates were calculated using a continuity equation with data on local metal content and growth velocity. Deposition rates of both metals are generally highest in the rapidly elongating region, 1.5-3.5 mm, even where metal concentration is decreasing with position and root age and even when the accumulation is inhibitory to growth.
Planta 02/2009; 229(4):945-54. · 3.00 Impact Factor
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ABSTRACT: The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II), Zn (II), Cd (II) and Cr (VI) on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves. A clear hormesis phenomenon was observed in all four testing metals at low concentrations under the condition of luminescence assays.
Biological research 01/2009; 42(2):183-7. · 1.03 Impact Factor
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ABSTRACT: The present study was conducted to determine the abilities of the living and nonliving Pseudomonas putida CZ1 cells, clays (goethite, kaolinite, smectite and manganite) and their composites to accumulate copper and zinc from a liquid medium, and elucidate the role of microbes on the mobility of heavy metals. Various mixtures of bacteria and clays were exposed to solutions of 0.025 mM or 0.5mM Cu(II) and Zn(II) in 0.01M KNO(3) to differentiate between so-called "high-affinity" sites and "low-affinity" sites. Clays associated in an edge-on orientation to the cells was observed by electron microscope (EM) examination of these metal-treated bacteria-clay aggregates. Adsorption experiments and desorption with 1.0M CH(3)COOK solution indicated that clays contain more high-affinity copper binding sites and less high-affinity zinc binding sites than that of bacteria, however, bacteria are involved in more low-affinity heavy-metal-binding sites. Carboxyl group activity is more important at weak-binding sites than at strong-binding sites. TEM-EDS analysis confirmed that most of Zn removed from solution was associated with P. putida CZ1 in the composites. These results suggest that bacteria play an important role in regulating the mobility of heavy metals in the soil environment.
Bioresource technology 06/2008; 100(1):330-7. · 4.25 Impact Factor
