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Cadmium Accumulation (cadmium + accumulation)
Selected AbstractsCompetition among zinc, manganese, and cadmium uptake in the freshwater alga Scenedesmus vacuolatusENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2007Stefanie Töpperwien Abstract In the present study, Zn and Mn competition with Cd uptake was investigated in the freshwater alga Scenedesmus vacuolatus. Scenedesmus vacuolatus was exposed to experimental media with Cd and either Zn or Mn in short-term experiments; long-term experiments were undertaken to investigate the effect of growth on Cd accumulation. Cadmium accumulation in S. vacuolatus could be detected at very low exposure concentrations (free Cd2+, 2 × 10,14 to 1 × 10,11 M), and uptake was proportional to the free-Cd2+ concentration. Zinc was an effective competitive inhibitor of Cd uptake when the Zn2+ to Cd2+ ratio was greater than 14 in the exposure medium, whereas Mn competed with Cd for uptake above a Mn2+ to Cd2+ ratio of greater than 10,000. Binding constants for Cd and Zn affinity to the transport sites were determined (KZn and KCd). Values for KZn were slightly higher (log K = 9.4,9.8) than values for KCd (log K = 8.9,9.8). In contrast, Cd seemed not to compete with the Mn-binding sites for uptake over the Mn concentration range from 1 × 10,10 to 1 × 10,8 M. Determined values for the binding constants of Zn and Cd show that a simple model can be applied to predict Cd uptake at known Zn and Cd concentrations. The environmental implications of these results are discussed with respect to potential Cd toxicity for aquatic organisms. [source] Cadmium accumulation by invertebrates living at the sediment,water interfaceENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2001Landis Hare Abstract Benthic animals can take up trace metals both from the sediment compartment in which they burrow and from the water column compartment above their burrows (we define both compartments as containing water and particles). If criteria for the protection of benthic animals are based on metal concentrations in one of these two compartments, then it should first be demonstrated that the majority of the metal taken up by these animals comes from the given compartment. To determine whether benthic animals take up the majority of their cadmium (Cd) from the sediment compartment, we created a Cd gradient in lake sediment and compared Cd accumulation by the invertebrates colonizing these sediments with Cd concentrations in the sediment compartment. On the basis of this relationship and using a bioaccumulation model, we estimate that indigenous benthic invertebrates take up the majority of their Cd from the water column compartment. The results of our experiment are similar to those from a previous study conducted on a different benthic community in a larger lake. Taxa common to both lakes obtained similar proportions of their Cd from the water column compartment, suggesting that Cd accumulation by the same species will be constant across lakes of differing size and chemistry. Our results strengthen the argument that the protection of benthic communities from metal pollution should consider metal in both the water column and sediment compartments. In this regard, the AVS model, which considers only sedimentary metals, was more effective in predicting Cd concentrations in pore waters than those in most animal taxa. We suggest that measurements of vertical chemical heterogeneity in sediments and of animal behavior would aid in predicting the bioaccumulation and effects of sedimentary pollutants. [source] Cadmium accumulation and binding characteristics in intact Sertoli/germ cell units, and associated effects on stage-specific functions in vitro: insights from a shark testis modelJOURNAL OF APPLIED TOXICOLOGY, Issue 2 2008Leon M. McClusky Abstract The increased human use of cadmium (Cd) and its increased occurrence in the environment is of concern. The testis is sensitive to Cd because of the steroid-mediated regulation of spermatogenesis, high levels of DNA synthesis and gene transcription, all of which varies in a stage-related manner. Validated techniques (acridine orange vital staining to detect apoptosis and dextran-rhodamine exclusion to assess blood,testis barrier function) were recently developed and the shark testis was proposed as an alternative model for assessing stage-specific functions in living testicular tissue and to study toxicant actions on spermatogenesis. The present paper shows that 109Cd accumulation and binding in vitro was stage-dependent (premeiotic, PrM > meiotic, M > postmeiotic, PoM), rapid and persisted in spermatocysts (intact germ cell/Sertoli cell units) 49 h after washout. In competitive binding analyses of all three spermatocyst stages, Hg, but not Zn, could replace bound 109Cd, suggesting that Cd binding was specific. These findings were associated with a biphasic apoptotic response in the PrM spermatocysts, which was maximal at 10 µm CdCl2 and 1 µm CdCl2 after 2 and 4 days in culture, respectively. Although Cd uptake in PoM cysts was more than 2-fold less than uptake in PrM cysts, the percentage dextran-rhodamine permeant PoM cysts was ,8-fold greater than in controls in the presence of both 10 µm CdCl2 and 30 µm CdCl2 after 4 days culture, indicating that blood,testis barrier function in PoM spermatocysts was compromised. These findings demonstrate that this model has utility for use in screening assays of environmental toxicants. Copyright © 2007 John Wiley & Sons, Ltd. [source] Histopathological alterations in the edible snail, Babylonia areolata (spotted babylon), in acute and subchronic cadmium poisoningENVIRONMENTAL TOXICOLOGY, Issue 2 2005P. Tanhan Abstract Histopathological alterations in 6- to 8-month-old juvenile spotted babylon, Babylonia areolata, from acute and subchronic cadmium exposure were studied by light microscopy. The 96-h LC50 value of cadmium for B. areolata was found to be 3.35 mg/L, and the maximum acceptable toxicant concentration (MATC) was 1.6 mg/L. Snails were exposed to 3.35 and 0.08 mg/L (5% of MATC) of cadmium for 96 h and 90 days, respectively. After exposure the gill, the organs of the digestive system (proboscis, esophagus, stomach, digestive gland, and rectum), and the foot were analyzed for cadmium accumulation. The results showed that most digestive organs had a high affinity for cadmium. The main target organ was the stomach, which could accumulate on average 1192.18 ,g/g dry weight of cadmium. Cadmium was shown to accumulate to a lesser extent in the digestive gland, gill, rectum, esophagus, proboscis, and foot. Histopathological alterations were observed in the gill and digestive organs (proboscis, esophagus, stomach, and rectum). The study showed that the stomach and gill were the primary target organs of both acute and subchronic exposure. Gill alterations included increased size of mucous vacuoles, reduced length of cilia, dilation and pyknosis of nuclei, thickening of basal lamina, and accumulation of hemocytes. The epithelial lining of the digestive tract showed similar alterations such as increased size of mucous vacuoles, reduced length of cilia, and dilation of nuclei. In addition, fragmentation of the muscle sheath was observed. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 142,149, 2005. [source] Kinetics of cadmium accumulation in periphyton under freshwater conditions,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2009Philippe Bradac Abstract The aim of the present study was to investigate the kinetics of cadmium (Cd) accumulation (total and intracellular) in periphyton under freshwater conditions in a short-term microcosm experiment. Periphyton was precolonized in artificial flow-through channels supplied with natural freshwater and then exposed for 26.4 h to nominal Cd concentrations of 5 and 20 nM added to natural freshwater. Labile Cd in water determined with diffusion gradient in thin films was 60 to 69% of total dissolved Cd in the exposure channels and 11% in the control channel. Intracellular Cd concentrations in periphyton increased rapidly and linearly during the first 71 min. Initial intracellular uptake rates were 0.05 and 0.18 nmol of Cd/g of dry weight × min in the 5 nM and 20 nM exposures, respectively. The subsequent intracellular uptake was slower, approaching steady state at the end of Cd exposure. Uptake kinetics of Cd was slower when compared to experiments with planktonic algal cultures, probably due to diffusion limitations. Intracellular Cd uptake during the entire exposure was modeled with a nonlinear, one-compartment model from which uptake and clearance rate constants, as well as bioconcentration factors, were obtained. The release of Cd from periphyton after the end of Cd exposure was slow when compared to the initial uptake rates. [source] The role of ZIP8 down-regulation in cadmium-resistant metallothionein-null cellsJOURNAL OF APPLIED TOXICOLOGY, Issue 5 2009Hitomi Fujishiro Abstract The mechanisms of cellular cadmium uptake in mammalian cells remain obscure. To solve this problem, we established cadmium-resistant cells (A7 and B5) from metallothionein-null mouse cells, and found that cadmium accumulation was markedly suppressed in these cells. DNA microarray and real-time PCR analyses revealed that expressions of ZIP (Zrt-, Irt-related protein) 8 and ZIP14 were down-regulated in A7 and B5 cells. In particular, both mRNA and protein levels of ZIP8 were markedly suppressed in A7 and B5 cells. Introduction of short hairpin RNA (shRNA) of ZIP8 into parental cells reduced the accumulation of cadmium to about 35% of that of mock-transfected cells, whereas the introduction of shRNA of divalent metal transporter 1 hardly changed cadmium accumulation. Thus, the cadmium resistance in A7 and B5 cells may be conferred primarily by the down-regulation of ZIP8. In mouse tissues, high expression of ZIP8 was noted in the liver, kidney, lung and testis. These data suggest that ZIP8 plays an important role in cellular uptake of cadmium. Copyright © 2009 John Wiley & Sons, Ltd. [source] Influence of salinity on lead and cadmium accumulation by the salt cedar (Tamarix smyrnensis Bunge)JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2009Eleni Manousaki Abstract BACKGROUND: The removal of heavy metals from polluted soils through the use of suitable plants has attracted much interest over recent decades. In this study Tamarix smyrnensis Bunge has been investigated for the characterization of its metal tolerance and ability to accumulate Pb and Cd, in order to evaluate its effectiveness as a cleanup tool for phytoextraction applications. For this purpose, two hydroponic experiments were performed, one with lead at concentration 100 ppm and a second with cadmium at concentration 5 ppm and at three different salt concentrations (0, 100, 200 mmol L,1 NaCl). RESULTS: The experimental results showed that Pb and Cd accumulation in shoots ranged from 150,270 ppm and 7.5,42 ppm, respectively, and salinity was found to increase metal accumulation in shoots. However, the presence of high metal and salt concentrations affected negatively the health and finally the survival of the plants. CONCLUSION:T. smyrnensis is neither a Pb nor a Cd hyperaccumulator; however, metal accumulation levels in shoots considered together with its high biomass production suggest that it could be used for phytoextraction applications. Furthermore, salinity has a positive influence on Pb and Cd accumulation in harvestable parts of the plant when it remains in low concentrations. Copyright © 2009 Society of Chemical Industry [source] Copper, zinc, and cadmium accumulation in two prairie soils and crops as influenced by repeated applications of manure,JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2007Sarah L. Lipoth Abstract A study was conducted to determine the effect of repeated (5,7 y) annual application of liquid swine or solid cattle manure on the plant availability of copper (Cu), zinc (Zn), and cadmium (Cd) at two field sites in the W-central and E-central agricultural regions of Saskatchewan, Canada. Soil samples, plant-straw and grain samples from the 2003 growing season were collected and analyzed for total Cu, Zn, and Cd concentrations using nitric acid microwave digestion followed by atomic-absorption spectroscopy. An ammonium bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA) extraction was performed on the soil samples as a measure of the plant-available fraction. Crop plants that were tested included wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). The results of this study indicated that long-term repeated applications of manure fertilizer sometimes resulted in increased plant availability of Cu, Zn, and Cd, as reflected in increased concentrations of the plant-available metal observed both in the soil and plant tissue. In the case of Cu and Zn, these increases were related to the rate of application, as the manure is a source of Cu and Zn. Changes in soil conditions from repeated manure application, including a decrease in pH and stimulated plant-root growth can explain the effect that both manure and urea-fertilizer application had on increasing the Cd concentration in the plant. Overall, there does not appear to be any concern about soil metal loading and plant accumulation in these soils after 5,7 y of manure application, as soil and plant concentrations were well below the allowable limits. [source] Role of mineral nutrition in minimizing cadmium accumulation by plantsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 6 2010Nadeem Sarwar Abstract Cadmium (Cd) is a highly toxic heavy metal for both plants and animals. The presence of Cd in agricultural soils is of great concern regarding its entry into the food chain. Cadmium enters into the soil,plant environment mainly through anthropogenic activities. Compounds of Cd are more soluble than other heavy metals, so it is more available and readily taken up by plants and accumulates in different edible plant parts through which it enters the food chain. A number of approaches are being used to minimize the entry of Cd into the food chain. Proper plant nutrition is one of the good strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain. Plant nutrients play a very important role in developing plant tolerance to Cd toxicity and thus, low Cd accumulation in different plant parts. In this report, the role of some macronutrients (nitrogen, phosphorus, sulfur and calcium), micronutrients (zinc, iron and manganese), and silicon (a beneficial nutrient) has been discussed in detail as to how these nutrients play their role in decreasing Cd uptake and accumulation in crop plants. Copyright © 2010 Society of Chemical Industry [source] Alternate wetting and moderate soil drying increases grain yield and reduces cadmium accumulation in rice grainsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2009Jianchang Yang Abstract BACKGROUND: Rice is the most important staple food in Asia but has also been identified as one of the major sources of cadmium (Cd) intakes for some Asian population. This study investigated whether grain yield could be maintained but Cd in grains be reduced through proper irrigation management when rice was grown in Cd-contaminated soil. RESULTS: Compared to the well watered treatment, the alternate wetting and moderate soil drying (MD, re-watered when soil water potential decreased to ,20 kPa) increased grain yield by 10,12% and improved milling and appearance quality of rice when grown in a soil containing a water-soluble Cd content of 18 g kg,1. An alternate wetting and severe soil drying (SD, re-watered when soil water potential decreased to ,40 kPa) showed an opposite effect. Both MD and SD significantly increased Cd content in roots while they reduced it in the straw. MD reduced Cd content by 19,21% in the grain and by 40% in milled rice. The SD significantly increased Cd content in the grain but reduced it in milled rice. CONCLUSION: An alternate wetting and moderate soil drying could increase rice yield and quality and also reduce Cd in the diet of rice. Copyright © 2009 Society of Chemical Industry [source] Variations in cadmium accumulation among rice cultivars and types and the selection of cultivars for reducing cadmium in the dietJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2005Jianguo Liu Abstract A pot trial was conducted with 52 rice cultivars of different types collected from different origins. The results showed that there were great differences in Cd concentrations in straw, brown rice and grain chaff among the rice cultivars grown in a soil containing a Cd concentration of 100 mg kg,1; the Cd concentrations in brown rice ranged from 0.22 to 2.86 mg kg,1. The great genotypic differences in Cd concentrations indicated that it is possible to lower the Cd content of rice through cultivar selection and breeding. Significant differences were found in the Cd concentrations of the rice types of Indica consanguinity and those of Japonica consanguinity, but not between their origins. There were significant correlations between straw and brown rice in Cd concentration and in the total amount of Cd accumulated. The distribution ratios of the Cd accumulated in brown rice to the total Cd accumulation in the above-ground rice plant varied greatly from 12.9 to 137.8 g kg,1, and there was significant correlation between the distribution ratios and Cd concentrations in brown rice. These indicated that Cd concentration in rice grain is governed by the transport of Cd from root to shoot and also from shoot to grain. Cd concentrations in brown rice also correlated significantly with some important agronomic traits, as well as with nitrogen concentrations, one of the most important criteria for rice quality. Copyright © 2004 Society of Chemical Industry [source] Characterization of cadmium uptake, translocation and storage in near-isogenic lines of durum wheat that differ in grain cadmium concentrationNEW PHYTOLOGIST, Issue 2 2006Jonathan J. Hart Summary ,,Here we examined several physiological properties of two near-isogenic lines of durum wheat (Triticum turgidum var. durum) that differ in grain cadmium accumulation, to identify the function of a gene locus that confers differential grain Cd concentrations. ,,Time- and concentration-dependent uptake and translocation studies using 109Cd were conducted on nutrient solution-grown seedlings. Root extracts were analysed by inductively coupled plasma emission spectrometry, gel filtration and capillary electrophoresis to determine the interaction between Cd and phytochelatins (PCs) in storage of Cd in roots. ,,The two isolines did not differ in time- or concentration-dependent root Cd uptake, but the low grain-Cd-accumulating isoline showed decreased movement of Cd from roots to shoots. All buffer-soluble Cd extracted from roots of both isolines was in the form of a low-molecular-weight PC-containing complex. ,,The data suggest that PC synthesis is not a limiting factor in the differential storage of Cd in roots, and that movement of Cd through the root and into the transpiration stream may be the cause of differential Cd partitioning in the two isolines. [source] Zinc effects on cadmium accumulation and partitioning in near-isogenic lines of durum wheat that differ in grain cadmium concentrationNEW PHYTOLOGIST, Issue 2 2005Jonathan J. Hart Summary ,,Here, we examined the effectiveness of two approaches for reducing cadmium (Cd) accumulation in durum wheat (Triticum turgidum L. var durum) grain: the application of supplemental zinc (Zn), and the use of cultivars exhibiting reduced grain Cd concentrations. ,,Two durum wheat near-isogenic lines (NIL) that differ in grain Cd accumulation were grown to maturity in solution culture containing a chelating agent to buffer the free activities of Zn and Cd at levels approximating those of field conditions. ,,The low Cd accumulating (L-Cd) isoline had Cd concentrations, in grains and shoot parts, which were 60,70% lower than those of the high Cd accumulating (H-Cd) isoline. Increasing the Zn activities in the nutrient solution from deficient to sufficient levels reduced the concentration of Cd in grains and vegetative shoot parts of both isolines. ,,The results suggest that supplemental Zn reduces Cd tissue concentrations by inhibiting Cd uptake into roots. Cd partitioning patterns between roots and shoots and between spike components suggest that the physiological basis for the low Cd trait is related to the compartmentation or symplasmic translocation of Cd. [source] Evaluation of Transgenic Poplars Over-Expressing Enzymes of Glutathione Synthesis for Phytoremediation of CadmiumPLANT BIOLOGY, Issue 6 2002A. Koprivova Abstract: Recently, phytoremediation of soils polluted with heavy metals has received a lot of attention. Since glutathione (GSH) and its derivatives (e.g., phytochelatins) play a major role in plant defence against environmental pollutants, we tested the effects of over-expression of bacterial genes for GSH synthesis in poplar on cadmium accumulation. A pilot experiment with CdCl2 in hydroponics revealed that poplars over-expressing ,-glutamylcysteine synthetase (,-ECS) accumulated significantly more Cd in root tissue than wild type or glutathione synthetase over-expressing poplars. To test the partitioning of Cd in different organs, poplar lines over-expressing ,-ECS in the cytosol and in chloroplasts were treated with 0.2 mM CdCl2 in hydroponics. Significant amounts of Cd were translocated to leaves, but significant differences in Cd accumulation were not observed between transgenic and wild type plants. To evaluate these lines for large-scale phytoremediation of cadmium, plants were treated with 2 mM Cd in soil. Over a four-week period, the poplar plants were able to accumulate up to 5.3 mg Cd. Most remarkably, in young leaves of both transgenic lines, Cd was accumulated to concentrations 2.5 - 3 times higher than in the wild type. The increased allocation of cadmium to the young leaves represents a potentional advantage for the phytoremediation process using the same plants over several vegetation periods. The use of transgenic poplar lines with enhanced glutathione production capacity seems to be of particular advantage in highly polluted soils. [source] Increased cysteine availability is essential for cadmium tolerance and accumulation in Arabidopsis thalianaPLANT BIOTECHNOLOGY JOURNAL, Issue 6 2004José R. Domķnguez-Solķs Summary Employing genetic transformation using an Atcys-3A cDNA construct expressing the cytosolic O -acetylserine(thiol)lyase (OASTL), we obtained two Arabidopsis lines with different capabilities for supplying cysteine under metal stress conditions. Lines 1-2 and 10-10, grown under standard conditions, showed similar levels of cysteine and glutathione (GSH) to those of the wild-type. However, in the presence of cadmium, line 10-10 showed significantly higher levels. The increased thiol content allowed line 10-10 to survive under severe heavy metal stress conditions (up to 400 µm of cadmium in the growth medium), and resulted in an accumulation of cadmium in the leaves to a level similar to that of metal hyperaccumulator plants. Investigation of the epidermal leaf surface clearly showed that most of the cadmium had accumulated in the trichomes. Furthermore, line 10-10 was able to accumulate more cadmium in its trichomes than the wild-type, whereas line 1-2 showed a reduced capacity for cadmium accumulation. Our results suggest that an increased rate of cysteine biosynthesis is responsible for the enhanced cadmium tolerance and accumulation in trichome leaves. Thus, molecular engineering of the cysteine biosynthesis pathway, together with modification of the number of leaf trichomes, may have considerable potential in increasing heavy metal accumulation for phytoremediation purposes. [source] Effects of dietary squid viscera meal on growth and cadmium accumulation in tissues of Japanese seabass, Lateolabrax japonicus (Cuvier 1828)AQUACULTURE RESEARCH, Issue 11 2006Kangsen Mai Abstract Cadmium (Cd) is a toxic environmental pollutant with a long biological half-life and can produce both hepatic and renal injuries in mammals and fish. Squid viscera meal (SVM), an effective attractant for aquatic animals, is widely used as an ingredient in aquafeeds. However, SVM is rich in Cd and its complexes. A study was conducted to evaluate the effects of dietary SVM on the growth and Cd deposition in tissues of Japanese seabass, Lateolabrax japonicus. Three practical diets were formulated to contain 0, 50 and 100 g SVM kg,1 diet, respectively, containing 0.21, 7.26 and 12.08 mg Cd kg,1 diet. Each diet was randomly assigned to triplicate groups of 80 Japanese seabass (mean initial weight, 10.89±0.21 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Fish were fed twice daily (06:30 and 16:30 hours) to satiation for 8 weeks. The results showed that there were no significant differences in fish survival among three dietary treatments, but significant higher specific growth rates (SGR) were observed in the fish fed diets with 50 or 100 g SVM kg,1 diet than that from the control group (P<0.05). The Cd concentrations in the kidney, liver and gill were found in a decreasing order at each treatment, and positively correlated with dietary Cd levels. Fish fed diets with 50 and 100 g SVM kg,1 diet had significantly higher Cd accumulations in the kidney (3.25, 5.85 mg kg,1), liver (0.76, 1.26 mg kg,1) and gill (0.42, 0.58 mg kg,1) compared with the control group (0.82, 0.34 and 0.32 mg kg,1 respectively) (P<0.05). The Cd concentration in fish muscle; however, was undetectable in any treatment. Therefore, based on these results, accumulation of Cd in edible tissue (muscle) of farmed Japanese seabass is not a food safety issue. However, long-term feeding of diets with SVM may result in accumulation of Cd in the kidneys, liver and gills of fish. [source] | ||||||||||||||||