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1.
Abstract

Gel filtration chromatography (with Sephadex G25, G50 and G100) was used to separate the different forms of thallium (Tl) and cadmium (Cd) in the cytosol fraction of Lemna minor and to examine the influence of the duration of metal exposure on the speciation of the two elements. A major proportion of Cd in the soluble phase was found to be bound to three groups of proteinaceous and polypeptide fractions; two of these, the high molecular weight protein fraction (Mr > 150,000) and the low polypeptide sized moieties of about Mr 1,500 or less were constitutive entities, whereas the intermediate sized fraction (Mr 7,000 - 8,000) could only be detected in plants previously exposed to Cd. After 12 days of exposure to Cd this fraction accounted for the greatest part of the bound Cd in Lemna tissues. Extending the period of exposure from 18 hours to 12 days resulted in a shift in the distribution of Cd between the low and intermediate fractions. Evidence for Tl-protein binding was limited and confined to the high molecular weight fraction, and most of the Tl in the soluble phase was present in a form closely allied to the free ion. The contrasting behaviour between the two elements has been interpreted in terms of the differences in their physicochemical properties.  相似文献   

2.
Siegesbeckia orientalis L. is a promising species for cadmium (Cd) phytoextraction with large biomass and fast growth rate, while little information about their intracellular mechanisms involved in Cd tolerance and detoxification has been explored. A soil pot experiment with total target Cd concentrations of 0, 10, 50, 100, and 150 mg kg?1 were designed to investigate the subcellular distribution, chemical forms and thiol synthesis characteristics of Cd in S. orientalis. More than 90% of Cd was bound to the soluble fractions (48.4–76.5%) and cell walls (19.9–46.3%). Increasing soil Cd concentrations enhanced Cd sequestration into the cell walls. Most of the Cd (69.8–82.7%) in the plant organ was mainly in the forms of pectate and protein integrated Cd and undissolved Cd phosphate, while a minor portion (6.8–20.9%) was in the forms of the inorganic Cd and the water soluble Cd. Nonprotein thiols and phytochelatins significantly increased with increasing soil Cd treatment levels, while glutathione concentrations had no obvious change trends. Therefore, intracellular detoxification mechanisms of Cd in S. orientalis mainly rely on formation of less toxic Cd chemical forms, store of a large amount of Cd in cell wall and synthesis of thiol compounds.  相似文献   

3.
Although Platycodon grandiflorum (Jacq.) A.DC. is a renowned medicine food homology plant, reports of excessive cadmium (Cd) levels are common, which affects its safety for clinical use and food consumption. To enable its Cd levels to be regulated or reduced, it is necessary to first elucidate the mechanism of Cd uptake and accumulation in the plant, in addition to its detoxification mechanisms. This present study used inductively couple plasma-mass-spectrometry to analyze the subcellular distribution and chemical forms of Cd in different tissues of P. grandiflorum. The experimental results showed that Cd was mainly accumulated in the roots [predominantly in the cell wall (50.96%–61.42%)], and it was found primarily in hypomobile and hypotoxic forms. The proportion of Cd in the soluble fraction increased after Cd exposure, and the proportion of insoluble phosphate Cd and oxalate Cd increased in roots and leaves, with a higher increase in oxalate Cd. Therefore, it is likely that root retention mechanisms, cell wall deposition, vacuole sequestration, and the formation of low mobility and low toxicity forms are tolerance strategies for Cd detoxification used by P. grandiflorum. The results of this study provide a theoretical grounding for the study of Cd accumulation and detoxification mechanisms in P. grandiflorum, and they can be used as a reference for developing Cd limits and standards for other medicine food homology plants.  相似文献   

4.
镉和锌在皖景天细胞内的分布及化学形态   总被引:11,自引:0,他引:11  
运用差速离心法和化学试剂逐步提取法,分析了Cd和Zn在皖景天根、茎和叶的亚细胞分布及其化学形态.结果表明:10 μmol·L-1 Cd处理下,Cd在皖景天细胞内的主要分布位点是其可溶部分;在100 μmol·L-1 Cd处理下,Cd在根中主要分布在细胞壁、茎中主要分布在细胞壁和可溶部分、叶中超过90%的Cd分布在可溶部分.高Cd浓度处理时,皖景天根、茎和叶的细胞壁中Cd分布比例增加,而可溶部分Cd分布比例相对减少.在1和800 μmol·L-1 Zn处理条件下,Zn在皖景天根、茎和叶的主要分布位点是可溶部分;高Zn浓度处理时,皖景天叶、茎和根的可溶部分和细胞壁中Zn的分布比例无明显变化.细胞器中Zn和Cd分布都很少.Cd在皖景天根、茎和叶内主要以氯化钠提取态和水提取态存在,Zn在皖景天根、茎和叶内以多种化学形态存在.  相似文献   

5.
Abstract

Concentrations of surface soil Zn and Cd from agricultural areas of the Henan Province were measured. About 234 soil samples were collected. Total metal analyses, sequential chemical fractionation which were divided into seven fractions according to the method of the Geological Survey Technical Standard (DD2005-03) set by the China Geological Survey were carried out on the samples. Total Cd and Zn concentrations of the topsoil were 0.1909 (0.1–0.549) and 63.07 (33.3–344.3) mg kg?1 respectively. Compared with the values permitted in China’s control standards for soil (GB 15618–1995) and background value in Henan Province, the soil samples showed high levels of Cd. The soil organic carbon has a significantly positive correlation with Cd and Zn concentration in the soil. Significant positive correlation between pH and Cd, Zn concentration was observed. On average, the order of Cd in each fraction was exchangeable, (27.3%)>weakly bound to organic matter; (22.7%)>strongly bound to organic matter; (16.4%)>residual; (15.1%)>carbonate; (12.1%)>Fe/Mn oxide bound; (4.5%)>water soluble; (2.0%), Zn was residual; (66.3%)>Fe/Mn oxide bound; (10.9%)> weakly bound to organic matter; (9.4%)> exchangeable; (6.0%)> strongly bound to organic matter; (3.9%)> carbonate (2.9%)> water soluble (0.6%). The accuracy of the sequential extraction was judged by the relative error (RE). RE for Cd ranged from 0 to 45% with a mean of 16.3%. RE for Zn ranged from 0.1 to 11.4% with a mean of 3.4%. On average, bioavailability index (BI) for Cd and Zn was 39.1% and 9.0% respectively. The mobility of the elements in the order Cd> Zn corresponds with the plant-availability of individual elements. Comparisons between activities of Cd2+ and Zn2+ calculated by Sauve semi-mechanistic equations and that of the water soluble fractions were demonstrated. The activities of Cd2+ and Zn2+ calculated by the semi-empirical equation are lower than its water soluble fraction.  相似文献   

6.
This study investigated the subcellular distribution and chemical forms of cadmium (Cd) in Hydrilla verticillata and the physiological mechanism underlying H. verticillata responses to Cd stress. Hydrilla verticillata was grown in a hydroponic system and was treated with various Cd concentrations (0, 10, 50, 100, 125, and 150?µM) for 7?days. Cadmium analysis of the leaves at the subcellular level showed that Cd was mainly stored in the soluble fraction (77.98–83.62%) and in smaller quantities in the cell wall fraction (11.99–17.30%) and the cell organelles (4.30–4.88%). The Cd taken up by H. verticillata was in different chemical forms. In the leaves and stems, the Cd was mostly extracted using 1?M NaCl and smaller amounts of Cd were extracted using 2% acetic acid. The malondialdehyde content significantly increased at all Cd concentrations, which indicated oxidative stress. The superoxide dismutase, guaiacol peroxidase, and catalase activities were enhanced. The proline, ascorbate, and glutathione contents increased at lower Cd concentrations, but decreased consistently as the Cd concentration rose. These results suggest that H. verticillata can be successfully used in the phytoremediation of Cd-contaminated water.  相似文献   

7.
芦竹(Arundo donax)对多种重金属都有较好的耐受性,是植物修复技术较理想的选择,而关于芦竹对Cd和Tl胁迫生理反应的相关研究却较少,为了有效治理Cd和Tl的污染,本研究以芦竹为材料,通过添加不同浓度重金属Tl(4,10和20 mg·kg~(-1))、Cd(50,100和200 mg·kg~(-1))进行芦竹盆栽试验,测定芦竹的株高、分蘖数、叶绿素含量、光合生理指标以及Tl和Cd在芦竹中的累积量,探讨芦竹对Tl和Cd胁迫的响应机制。结果表明:Tl(4~20 mg·kg~(-1))和Cd(50~200 mg·kg~(-1))对芦竹株高、分蘖数以及叶绿素含量均无显著影响(P0.05);芦竹体内Tl和Cd含量随着Tl和Cd浓度的升高呈上升趋势,芦竹体内Tl含量的分布规律为根茎叶,Cd含量的分布规律:Cd浓度50 mg·kg~(-1)时为茎叶根,Cd浓度100和200 mg·kg~(-1)时为根茎叶,表明Tl和Cd主要分布在根部,芦竹对Tl、Cd有一定的富集能力。Cd和Tl处理均显著降低芦竹叶片的胞间CO2浓度,在Tl浓度为10 mg·kg~(-1)时,净光合速率、气孔导度和蒸腾速率得到显著提高,当Cd浓度为50 mg·kg~(-1)时,净光合速率、气孔导度和蒸腾速率得到显著提高。这表明芦竹对重金属Cd和Tl有较强的耐受性,可为Cd和Tl污染土壤的治理和修复提供参考。  相似文献   

8.
Subcellular distribution and chemical forms of cadmium in Morus alba L.   总被引:1,自引:0,他引:1  
Morus alba L. (mulberry) is a perennial woody tree and a species with great potential for Cd phyremediation owing to its large biomass and extensive root system. The mechanisms involved in Cd detoxification were investigated by analyzing the subcellular distribution and chemical forms of Cd in mulberry in the present study. These results indicated that 53.27–70.17% of Cd mulberry accumulated was stored in the root and only about 10% were in the leaves. Lots of the Cd was located in the cell wall of the mulberry root and in soluble fraction of the mulberry leaf. Moreover, in roots, the largest amount of Cd was in the form of undissolved Cd-phosphate. While in mulberry leaves and stems, most of the Cd was extracted by 2% Acetic acid and 0.6 M HCl, representing Cd-phosphate and Cd-oxalate. It could be concluded that the Cd combination with peptides and organo-ligands in vacuole of leaf or complexed with proteins or cellulose in the cell wall of root might be contributed to the tolerance of mulberry to Cd stress. The mulberry could be used to remediate the Cd polluted farmland soils.  相似文献   

9.
不同类型镉积累水稻细胞镉化学形态及亚细胞和分子分布   总被引:14,自引:0,他引:14  
利用水培试验结合亚细胞组分分级分离和凝胶过滤等技术,研究了水稻根和叶中镉的化学结合形态及其亚细胞和分子分布,比较了低镉积累品种“广源占No.3”和高镉积累品种 “珍桂矮”的差异.结果表明:随着营养液中镉浓度的升高,根和叶亚细胞镉含量显著上升,大部分镉积累在细胞壁(F)和细胞可溶部分(F).高镉积累品种“珍桂矮”根和叶中可溶部分镉含量显著高于低镉积累品种“广源占No.3”.根和叶各种形态镉中,以氯化钠提取态占优势,其次是醋酸提取态,盐酸提取态镉含量最低.与“广源占No.3”相比,“珍桂矮”中迁移性较强的去离子水和乙醇提取态镉比例较高.凝胶过滤结果表明,两种类型的水稻可溶部分镉的出峰位置与样品流份中可溶性蛋白的出峰位置大致相同.可溶部分中的镉大多与分子量为3kD的物质结合,属于植物鳌合肽(PCs)或低分子量物质.“广源占No.3” 根系中镉与PCs配合的组分(Cd-PCs)含量远小于“珍桂矮”.“广源占No.3”细胞可溶部分较低的镉含量以及根系中较少的Cd-PCs形成量,降低了镉的移动及其向地上部转运的可能性.  相似文献   

10.
Subcellular distribution and chemical form of cadmium in bean plants   总被引:30,自引:3,他引:27       下载免费PDF全文
The subcellular distribution and chemical form of Cd in bean plants grown in nutrient solutions containing Cd were investigated. Cd was accumulated mainly in roots and to a minor extent in leaves. Subcellular fractionation of Cd-containing tissues (pH 7.5) showed that more than 70% of the element was localized in the cytoplasmic fraction in roots as well as in leaves. Little Cd (8 to 14%) was bound either to the cell wall fraction or to the organelles. Gel filtration of the soluble fraction showed Cd to be associated mainly with 5,000 to 10,000 molecular weight components in roots, and 700 to 5,000 molecular weight components in leaves. Small amounts of Cd were found in the high molecular weight proteins (molecular weight 150,000). Only traces of Cd could be detected as a free ion. Chemical characterization of the low molecular weight components resulted in the identification of nine amino acids which were identical in roots and leaves. Cd in bean plants is assumed to be bound to peptides and/or proteins of low molecular weight.  相似文献   

11.
镉在旱柳中亚细胞分布及存在的化学形态   总被引:5,自引:1,他引:4  
以2个旱柳无性系幼苗为材料,通过营养液培养并结合差速离心与化学试剂提取法,分析了不同浓度Cd2+胁迫下旱柳叶和根中Cd的亚细胞分布及其存在的化学形态.结果显示,(1)随着培养介质Cd2+浓度升高,旱柳无性系幼苗叶和根中各亚细胞组分Cd含量随之增加.叶片的Cd主要富集于细胞壁、叶绿体和可溶性部分,它们的含量分别占65%~69%、14%~22%、6.8%~7.7%,仅少量Cd发现于膜部分;而根中Cd主要积累于细胞壁和可溶性部分,其中含量分别占59%~66%和14%~25%,Cd在根亚细胞组分中积累量依次为细胞壁>可溶性部分>质体>膜部分.(2)旱柳体内Cd以不同的化学形态存在,大部分为HCl(FHCl)、NaCl(FNaCl)、醋酸(HAC,FHAC)提取态,极少部分为乙醇(EtOH,FEtOH)和水提取态(Fwater),叶和根中5种Cd提取态含量依次为FHCl>FNaCl>FHAC>Fwater>FEtOH,而叶和根中HCl和NaCl提取态Cd占有比例大于30%以上.研究表明,旱柳无性系中Cd主要与蛋白质和有机酸螯合或以金属磷酸盐沉淀的形态存在,其根、叶的细胞壁和液泡在Cd忍耐与解毒中起到重要作用.  相似文献   

12.
Soybean (Glycine max L.) plants grown in nutrient solution were exposed to 1 mM Cd(NO3)2 for 24 h. Dynamics of distribution of cadmium among its different forms (water soluble, Ca-exchangeable and complexed) in the intercellular space and the ratio of the intercellular and intracellular cadmium in roots, stems and leaves were studied. In roots, in the beginning of treatment the largest portion of Cd was found in the intercellular space and 1 h later Cd content started to decrease, so that between 13- and 24-h treatment an equilibrium was reached in which about 70 % of Cd was found inside cells. In stems, already after 1-h treatment, the Cd concentrations in the cells and intercellular space were similar, the equilibrium being disturbed after 13 h, so that after 24-h treatment 80 % of Cd was found inside cells. In leaves, up to the 13 h Cd distribution showed fluctuation, after that equilibrium was reached, with 70 % of intracellular Cd. The highest contents of all Cd forms in the intercellular space was observed in roots.  相似文献   

13.
Impatiens walleriana plants accumulate sufficiently high concentrations of cadmium (Cd) for this species to be considered a potential Cd hyperaccumulator. Rooted cuttings were grown hydroponically for 25 and 50 days in solutions spiked with various Cd concentrations. The subcellular distribution and chemical forms of Cd in different organs were analyzed, and its upward translocation was also assessed. The plants accumulated large amounts of Cd; the Cd concentration in the roots and shoots reached 120–1900 and 60–1600 mg/kg, respectively. Regardless of the growth period, the Cd accumulated in the roots was primarily compartmentalized in the soluble fraction or ethanol and deionized water extractable chemical forms with high migration abilities. Translocation to the shoots was followed by an association of Cd mainly in the cell wall or with pectate and protein. The roots’ Cd showed a high migration capacity for predicting the shoots’ Cd concentrations. Different exposure periods significantly affected the subcellular distribution of Cd in the stems, and thus the upward translocation.  相似文献   

14.
Abstract

Total arsenic, inorganic arsenic (iAs), total cadmium concentrations and chemical forms of cadmium were analysed in Porphyra yezoensis collected monthly from January to April in 2011 and in Laminaria Japonica collected monthly from March to July in 2010. Results showed that total As concentrations in P. yezoensis were much lower than those in L. Japonica. The iAs concentrations in both macroalgae were all below the maximum limit according to the legislation in China, while total Cd concentrations in all samples of P. yezoensis exceeded the maximum limit. The percentage of iAs to total As decreased in both macroalgae with the time. The results provide important information showing that both macroalgae are able to metabolise inorganic arsenic to organic forms. Thus both macroalgae have evolved arsenic resistance which is linked to the capability of metabolising toxic inorganic arsenic. In addition, the results suggest that the transformation rate of arsenate to organic arsenic in both algae increases with the growth and metabolic rate that increase with elevated environmental temperature. Temperatures rise from January to April in Jiangsu province and from March to July in Liaoning Province. Most Cd was associated with pectates and protein (extractable by 1 M NaCl) in both algae, and only a small percentage of the Cd was inorganic (extractable by 80% ethanol). The Cd chemical forms have no obvious relationship with the time in both algae.  相似文献   

15.
Variation in Cd accumulation between Nicotiana species but not varieties has been observed in seedlings grown in solution culture with moderate-to-low levels of Cd. Nicotiana tabacum has been characterized as a leaf and root accumulator while Nicotiana rustica is shown to be primarily a root accumulator, having about half the leaf Cd per gram dry weight of N. tabacum. This phenotype is retained in the mature N. rustica plant. To characterize these two species which differ in their modes of Cd accumulation, tissue Cd distribution, partitioning of metal in soluble and insoluble fractions and the contribution of soluble Cd-binding proteins (peptides) to total plant Cd was assessed using mature solution cultured plants. Metal accumulation was highest in the most mature leaves and in young roots. The preponderance of young roots in N. rustica may, in part, account for low leaf/high root Cd accumulation in this species. While Cd-binding peptides appear to be a principal form of Cd in leaves and roots of seedlings and these also occur in mature leaves, Cd is equally distributed between soluble (about 80% as Cd-binding peptide) and uncharacterized insoluble forms in mature plant roots.  相似文献   

16.
Abstract

The speciation of aluminium in tea infusions and in vitro gastrointestinal digests of tea infusions has been investigated using size exclusion chromatography coupled to inductively coupled plasma mass spectrometry (SEC-ICP-MS). At pH 2.5, following simulated gastric treatment, Al from tea eluted at a similar retention volume to that obtained for an aqueous Al standard. At pH 5.5, an aqueous Al standard was eluted from an SEC column in Tris buffer (Al recovery ≈ 100%) only in the presence of a complexing agent (NaF), and at a retention volume corresponding to a molecular mass greater than that expected for an ionic species. Aluminium associated with a tea infusion eluted in two fractions: a higher molecular weight fraction corresponding to Al strongly bound to ligands in the tea, and a lower molecular weight fraction probably comprised of labile Al eluting as Al-F complexes. Simulated gastrointestinal digestion produced three Al-bearing fractions, of which the two at higher molecular mass represented ligand-bound Al. The molarity of the Tris buffer strongly influenced the retention volume of the Al fractions, particularly for the ligand-bound Al. After simulated gastrointestinal digestion, the soluble labile fraction (15% of the Al from the tea infusion) was considered to be potentially available for absorption. The actual proportion of the fraction that might be absorbed would depend upon a number of physiological and nutritional factors.  相似文献   

17.
This article discusses the mineralogy and geochemical characteristics of the fresh copper-flotation waste samples. The mobility of As, Cd, Cr, Cu, Ni, Pb, Tl, Zn was investigated by leaching tests. The main mineral phases identified concerned dolomite, quartz, clay minerals, feldspars, and copper-bearing minerals. Chemically, CaO and silica were dominating, along with a significant concentration of precious (Cu), refractory (Cr, Ti, V, Zr), and toxic (As, Cd, Pb) metals. Elements were bound mainly to the residual fraction and sulphides in the following order: Pb > Cu ≈ Tl > As ≈ Zn > Ni ≈ Cr > Cd. The metal mobility patterns expressed as a percentage of total concentrations, were as follows: Cd (42%) > Cr (26%)> Ni (24%) > Zn (23%) > As (22%) > Tl (20%) > Cu (18%) > Pb (2%). Those constituents were released earlier in lower pH values, although Cu, Cr, and Pb were also released in higher alkaline pH values. However, Zn release was not dependent on pH. When L/S values decreased, elements like As, Cr, Cu, Pb, and Tl were released. That process caused decrease of Cd, Ni, and Zn release.  相似文献   

18.
Abstract

The water quality of the Czarna Przemsza River source in Zawiercie was investigated in four sampling campaigns in years 2016 and 2017. Values of 62 indicators (physico-chemical, inorganic, organic, and biological) were compared with permissible limits for drinking water according to Polish legal acts and EU, WHO, USEPA, and Canadian guidelines. The water quality was determined as below good because of EC values and As, Ca, Cd, Cr, Cu, Se, and Zn concentrations. Water was also determined as non-potable due to exceeded concentrations of Al, As, Cd, Cr, Fe, K, Ni, Pb, Sb, and Se. The Human Health Risk Assessment for Zawiercie’s inhabitants was carried out, while water from the source is consumed regardless of its quality. The mean estimated daily intake (EDI) values exceeded Minimal Risk Level values forCr, Cd, As, Se, and Cu. The hazard index (HI) values pointed very high total non-carcinogenic risk in residential exposure scenario generated mainly by As, Cr(VI), Tl, Pb, MCPA, Se, and Cd. Water intake scenario based on questionnaire surveys pointed that risk for inhabitants existed (HI >1). The total carcinogenic risk (Rt) values were at the unacceptable level and decreased in the following order: Cr(VI) > As?>?Pb.  相似文献   

19.
The effect of excessive Cd on the growth and metal uptake by leafy vegetables Brassica chinensis L. (cv. Wuyueman) and Brassica pekinensis (Lour.) Rupr. (cv. Qingyan 87-114) were studied in hydroponic solution culture. The Cd concentration higher than 10 μM significantly decreased the root elongation and leaf chlorophyll contents of both plant species. The shoots of B. pekinensis had significantly higher concentrations of total and water-soluble Cd than B. chinensis. The roots of both species accumulated more Cd than the shoots in all the Cd treatments. Most of the Cd in the roots was found in the cell walls. The shoot/root ratio of Cd concentrations in B. pekinensis was always greater than that in B. chinensis. But, the concentration and proportion of Cd in the cell walls in B. chinensis were higher than that in B. pekinensis. Cadmium treatments also increased the concentrations of total non-protein thiols (NPT) in the shoots of the both species. A significant correlation was found between the concentrations of soluble Cd and NPT in plant shoots.  相似文献   

20.
The effects of Cd stress on the growth and Cd accumulation of Bougainvillea spectabilis Willd. as an ornamental plant and the related mechanisms were investigated in the study. We studied the impact of Cd on the plant ultrastructure, examined the cellular distribution of Cd, explored the Cd chemical forms and transformation, and determined the organic acid secretion in the plants. The results showed that B. spectabilis could grow well in the Cd treatment groups, and the roots could accumulate high concentration of Cd. The soluble fraction (primarily in the vacuole) as the form of citrate in leaves of B. spectabilis was the major compartment for Cd storage. The citric acid secreted by B. spectabilis played an important role in the detoxification of Cd, as well as the growth of plants and Cd accumulation. As an ornamental plant, B. spectabilis has the potential to be used in the phytostabilization of Cd-contaminated soils and can beautify the environment at the same time.  相似文献   

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