Concentrations Of Essential Metals Research Articles

Myelin Disturbances Produced by Sub-Toxic Concentration of Heavy Metals: The Role of Oligodendrocyte Dysfunction

Evidence has been accumulated demonstrating that heavy metals may accumulate in various organs, leading to tissue damage and toxic effects in mammals. In particular, the Central Nervous System (CNS) seems to be particularly vulnerable to cumulative concentrations of heavy metals, though the pathophysiological mechanisms is still to be clarified. In particular, the potential role of oligodendrocyte dysfunction and myelin production after exposure to subtoxic concentration I confirmed. It is ok of heavy metals is to be better assessed. Here we investigated on the effect of sub-toxic concentration of several essential (Cu2 +, Cr3 +, Ni2 +, Co2+) and non-essential (Pb2 +, Cd2+, Al3+) heavy metals on human oligodendrocyte MO3.13 and human neuronal SHSY5Y cell lines (grown individually or in co-culture). MO3.13 cells are an immortal human–human hybrid cell line with the phenotypic characteristics of primary oligodendrocytes but following the differentiation assume the morphological and biochemical features of mature oligodendrocytes. For this reason, we decided to use differentiated MO3.13 cell line. In particular, exposure of both cell lines to heavy metals produced a reduced cell viability of co-cultured cell lines compared to cells grown separately. This effect was more pronounced in neurons that were more sensitive to metals than oligodendrocytes when the cells were grown in co-culture. On the other hand, a significant reduction of lipid component in cells occurred after their exposure to heavy metals, an effect accompanied by substantial reduction of the main protein that makes up myelin (MBP) in co-cultured cells. Finally, the effect of heavy metals in oligodendrocytes were associated to imbalanced intracellular calcium ion concentration as measured through the fluorescent Rhod-2 probe, thus confirming that heavy metals, even used at subtoxic concentrations, lead to dysfunctional oligodendrocytes. In conclusion, our data show, for the first time, that sub-toxic concentrations of several heavy metals lead to dysfunctional oligodendrocytes, an effect highlighted when these cells are co-cultured with neurons. The pathophysiological mechanism(s) underlying this effect is to be better clarified. However, imbalanced intracellular calcium ion regulation, altered lipid formation and, finally, imbalanced myelin formation seem to play a major role in early stages of heavy metal-related oligodendrocyte dysfunction.

Mineral Content in Honeybee Wax Combs as a Measurement of the Impact of Environmental Factors.

Environmental pollution from metals needs to be constantly monitored due to their predominantly negative impacts on living organisms. As apian products stored in hives are considered useful bioindicators, the objective of this study was to: (a) investigate and compare the essential and toxic metal concentrations in freshly constructed combs (light combs, LC) and old combs (dark combs, DC) in use for two to three beekeeping seasons, and (b) compare the mineral content of beeswax combs from apiaries exposed to different levels of environmental pollution using the energy dispersive x-ray fluorescence method. Concentrations of ten elements (Cr, Pb, Cu, Ni, Fe, Zn, Mn, Sr, Rb, Ca) were determined in 18 honeybee wax comb samples from three apiaries in continental Croatia. The results showed that the influence of comb age and/or geographical origin (representing varying levels of environmental pollution exposure) on the elemental composition of beeswax was evident for the toxic elements Cr, Pb, Cu and Ni, and for the essential elements Fe, Zn, Mn and Sr, but not Rb. In addition to monitoring the environmental element content, wax combs can be used to determine contamination levels. Additionally, in-time analysis results can enable beekeepers to adjust management practices, such as moving apiaries to better positions. They can also be useful in the creation of policies on acceptable limits for toxic metal levels in particular geographical areas.

Autophagic elimination of Trypanosoma cruzi in the presence of metals.

Trypanosoma cruzi is an obligate intracellular parasite transmitted to vertebrate hosts by blood-sucking insects. Molecules present in parasites and mammalian cells allow the recognition and parasite internalization. Metallic ions play an essential role in the establishment and maintenance of host-parasite interaction. However, little is known about how parasites handle with essential and nonessential metal quotas. This study aimed to investigate the influence of metal ions on the biological processes of T. cruzi infected cells. Infected cells were incubated with ZnCl2, CdCl2, and HgCl2 for 12 h and labeled with different specific dyes to investigate the cellular events related to intracellular parasite death and elimination. Infected host cells and parasite's mitochondria underwent functional and structural disorders, in addition to parasite's DNA condensation and pH decrease on host cells, which led to parasite death. Further investigations suggested that lysosomes were involved in pH decrease and the double membrane of the endoplasmic reticulum formed vacuoles surrounding damaged parasites, which indicate the occurrence of autophagy for parasite elimination. In conclusion, low concentrations of nonessential and essential metals cause a series of damage to Trypanosoma cruzi organelles, leading to its loss of viability, death, and elimination, with no removal of the host cells.

Levels of Essential and Non-essential Metals in Garlic (Allium sativum L.) Samples Collected from Different Locations of East Gojjam Zone, Ethiopia

The concentrations of essential metals (Na, K, Ca, Mg, Fe, Zn, Mn, Cu, Co and Ni) and non-essential metals (Cd and Pb) in garlic samples were determined using flame photometer for Na and K, and flame atomic absorption spectrometry (FAAS) for the rest of the metals. The samples were collected from four agricultural areas (Debre Markos, Dejen, Bichena and Debre Werk), East Gojjam Zone, Ethiopia. Wet digestion method using a mixture of 4 ml HNO 3 and 1 ml HClO 4 was used for digestion of the samples. The results obtained revealed that the concentrations of metals in the garlic samples in mg/kg dry weight were in the range of: Na (244–306), K (6514–8592), Ca (3142–4004), Mg (798–1322), Fe (136–172), Zn (57.6–83.6), Mn (27.2–27.5), Cu (8.15–13.4), Co (11.4–28.3), Ni (14.1–19.6), Cd (0.10–0.14) and Pb (0.68–1.43), respectively. In general, the levels of metals in Allium sativum collected from all sampling site was found to be decreased in the order of: K > Ca > Mg > Na > Fe > Zn > Mn > Co > Ni > Cu > Pb > Cd. The levels of metals determined in the analyzed garlic samples were found below the WHO maximum permissible limit; hence they are safe for human consumption and can be considered as good sources of essential nutrients

Advantages and disadvantages of different pre-cooking and cooking methods in removal of essential and toxic metals from various rice types- human health risk assessment in Tehran households, Iran

The aim of present study was to evaluate the effects of different pre-cooking and cooking methods on the concentration of toxic (As, Cd and Pb) and essential (Fe, Cu, Co and Zn) metals in widely consumed rice types by Tehran households, Iran. In this regard, a total of 90 samples were obtained from Iranian, Pakistani and Indian rice brands (30 samples from each brand), and were examined in order to determine the concentration of toxic metals including As, Cd, Pb, Fe, Zn, Co and Cu using ICP-OES. Among these rice brands, the most contaminated one was selected in order to evaluate the effects of washing and soaking processes in different time points (1, 5 and 12 h), as well as different cooking methods (Rinsing and Kateh) in reducing the concentration of subjected metals. Nine samples were analyzed for each process, which were 54 samples in total. Our results show that the preparation and cooking methods applied for all rice brands (except for Indian rice) could effectively reduce the non-carcinogenic risk associated with these metals to the acceptable level; however, this is not true about the carcinogenic risk associated with arsenic. Finally, according to our findings it can be concluded that all cooking methods can lead to considerable removal of rice toxic metals (this is partially true about all available rice brands in Iran), however, a large amount of essential metals were also eliminated by these methods. Moreover, after cooking of different rice types in Iran, this food has still carcinogenic risk associated with arsenic.

Risk assessment of heavy metals and salts for human and irrigation consumption of groundwater in Qambar city: a case study

ABSTRACTThe study investigated the water quality of groundwater for consumption of human beings and irrigation of taluka Qamber district Qamber-Shahdadkot, Sindh, Pakistan. A total of 21 representative groundwater samples were collected mostly used for human consumption. According to the research work, 81% samples were not suitable for drinking purpose with TDS above the maximum permissible limit of WHO (1000 mg/L). The pH, total phosphate-P, orth ophosphate-P, nitrate-N, nitrite-N, and arsenic were within WHO limits. The concentrations of essential metals more than half samples were higher than WHO guideline. The concentrations of trace metals like Mn, Fe, Co, and Cu of all samples were within WHO limits, but the values of Cr and Ni 52.38%, Cd 57.14%, and Pb 28.57% were above the WHO limits. The concentrations of fluoride in 81% were higher than permissible limits of WHO. The high consumption of water with concentration of salts and fluoride above the permissible limits may be a leading factor of a number of diseases in the area.The water quality determined for irrigation based on Kelly index (KI), sodium percentage (Na%), chloride–sulfate ratio, sodium adsorption ratio (SAR), permeability index (PI), chloro alkaline indices1 (CAI-1), residual sodium carbonate (RSC), and chloride bicarbonate ratio indicated that 25–90% samples were suitable for irrigation purposes.

English

This study is aimed at determination of concentration of essential (Ca, K, Na and Mg) and heavy (Cd, Cr, Pb, Hg, Cu and Zn) metals using Flame Atomic Absorption Spectroscopy (FAAS) of samples taken from fresh roots of Moringa stenopetala. A wet digestion method involving use of mixture of (HCl and HNO3, ratio 3:1) and 10 ml of 30% H2O2 at an optimum temperature and time duration was deployed during sample preparations. Results show that concentration of essential elements Mg, Ca, Na, and K range from 10.12 to 10.99 mg/kg, 2.6 to 5.64 mg/kg, 4.3 to 5.26 mg/kg, and 1.26 to 1.77 mg/kg, respectively. Among the heavy metals, concentration of Cu fall in the range of 0.81_1.44 mg/kg while that of zinc fall in the range of 0.37_2.34 mg/kg, both lying below toxic level. The levels of toxic metals (Cd, Cr, Pb and, and Hg) were not detected. The results of the study indicate that the concentration of the entire essential and heavy metals are below the range of WHO/FAO limits. Key words: Moringa stenopetala, essential metals, heavy metals, roots, flame atomic absorption spectroscopy (FAAS) &nbsp

Concentration of Heavy Metals in Some Animal Meats from Merowe–City–Sudan

This study was to determine the concentrations of essential metals such as namely Copper, Cobalt, Manganese, Iron and Zinc) and heavy metals such as Cadmium and Lead performed by atomic absorption spectrophotometer (AAS) in two sample of some animal meats of Mutton (sheep) and Beef (cow), collected from the district popularly in Merowe-city, north Sudan. The essential metals estimation in the investigated samples indicated the following range of concentration (0.19 -0.28mg/kg) for Cobalt, (0.36-0.31mg/kg) for Copper, (3.16-5.44mg/kg) for Iron, (0.12-0.15mg/kg) for Manganese, and (5.30 -7.6mg/kg) for Zinc respectively. These concentrations of essential metals are in the range of human necessities. The concentration of toxic metals (Cadmium and lead) in two samples is not mean detected. The results also showed that were significant differences of some essential elements concentrations (Mg/kg) in two samples. Generally meat of Beef was found to have to highest significant levels of metals and the meat of Mutton lowest levels. The concentration of Iron and Zinc concentration in all samples were within the tolerance limits.

Aberrant gene expression profiles in Mediterranean sea urchin reproductive tissues after metal exposures

Marine organisms are simultaneously exposed to numerous pollutants, among which metals probably represent the most abundant in marine environments.In order to evaluate the effects of metal exposure at molecular level in reproductive tissues, we profiled the sea urchin transcriptional response after non-lethal exposures using pathway-focused mRNA expression analyses.Herein, we show that exposures to relatively high concentrations of both essential and toxic metals hugely affected the gonadic expression of several genes involved in stress-response, detoxification, transcriptional and post-transcriptional regulation, without significant changes in gonadosomatic indices.Even though treatments did not result in reproductive tissues visible alterations, metal exposures negatively affected the main mechanisms of stress-response, detoxification and survival of adult P. lividus. Additionally, transcriptional changes observed in P. lividus gonads may cause altered gametogenesis and maintenance of heritable aberrant epigenetic effects.This study leads to the conclusion that exposures to metals, as usually occurs in polluted coastal areas, may affect sea urchin gametogenesis, thus supporting the hypothesis that parental exposure to environmental stressors affects the phenotype of the offspring.

Placental concentrations of essential, toxic, and understudied metals and relationships with birth outcomes in Chattanooga, TN

BackgroundComprehensive examinations of placental metal concentrations and correlations with infant parameters are under-investigated. Chattanooga, Tennessee's consistently high incidence of low birth weight and potential for metal exposure provides an ideal opportunity to investigate potential correlations. ObjectivesTo investigate the associations between a wide variety of metals in placental tissue and multiple infant parameters. MethodsA total of 31 elements were screened via ICP-MS in 374 individual placental samples. Of those, 14 were quantifiable in > 86% of the samples. We examined correlations between metal concentrations and infant parameters (birth weight, gestational age, birth weight centile, placental weight, birth length and head circumference). We fit multivariable regression models to estimate the covariate-adjusted associations of birth weight with ln-transformed concentrations of each of the 14 metals and used generalized additive models to examine nonlinear relationships. ResultsSome of the strongest relationships with infant parameters came from several lesser-studied metals. Placental rhodium concentrations were negatively correlated with almost all infant parameters. In the fully adjusted regression model, birth weight was significantly associated with several metals. On an IQR (25th to the 75th percentile) basis, estimated changes in birthweight were: for cobalt (82.5 g, IQR=6.05 µg/kg, p = 0.006), iron (−51.5 g, IQR = 171800 µg/kg, p = 0.030), manganese (−27.2 g, IQR=152.1 µg/kg, p = 0.017), lead (−72.7 g, IQR=16.55 µg/kg, p = 0.004) and rhodium (−1365.5 g, IQR = 0.33 µg/kg, p < 0.001). Finally, a generalized additive model showed significant nonlinear relationships between birth weight and concentrations of Co and Rh. ConclusionsOur comprehensive examination of placental metals illustrate many strong associations between lesser-studied metals and infant parameters. These data, in combination with our correlations of well-studied metals, illustrate a need to consider in utero exposure to a broad array of metals when considering fetal development.

Determination of toxic and essential metals in rock and sea salts using pulsed nanosecond laser-induced breakdown spectroscopy.

A spectrometer based on pulsed nanosecond laser-induced breakdown spectroscopy (LIBS) was employed for the quantitative determination of heavy and essential metals in salts from various sources available in Pakistan. Six salt samples were collected from sea salt and rock salt. Toxic metals (Cu, Cd, and Ni) and other microessentials (Fe, Ca, Co, Mg, Mn, S, and Zn) were investigated from the recorded spectra. The detection system was calibrated using a parametric dependence study. The quantitative analyses were accomplished under the assumption of local thermodynamic equilibrium and optically thin plasma. The results by the LIBS technique were in agreement with the outcomes of the same samples studied using a more standard approach like inductively coupled plasma-atomic emission spectroscopy (ICP-AES). When the concentrations of heavy and essential metals were calculated using a calibration-free LIBS method that does not need a standard salt specimen and dilution, both LIBS and ICP-AES were also in good agreement. The limit of detection of the experimental set up was determined for the observed heavy metals in the studied samples.

Analysis of trace metal concentrations in raw cow's milk from three dairy farms in North Gondar, Ethiopia: chemometric approach.

Concentrations of essential (Cu, Mn, and Zn) and toxic (Cr, Cd, and Pb) trace metals in 30 raw cow's milk samples were quantified using flame atomic absorption spectrometry. The samples were collected from the Nara-Awudarda, Tana-Abo, and Kosoye Amba-Rass sites in North Gondar, Ethiopia, preserved in a deep freezer (-20°C), and then digested by Kjeldahl apparatus with HNO3/H2O2 (5:2; v/v) at 300°C for 2.5h. The data were subject to principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA). Overall hazard quotient (HQ) and carcinogenic risk (CR) values were also estimated to assess metal-related health risks. The mean concentrations of Cr, Mn, Cu, Zn, Cd, and Pb in the milk samples ranged 0.468-0.828, 1.614-2.806, 0.840-1.532, 1.208-5.267, ND-0.330, and ND-0.186mg/kg, respectively. The lowest values were obtained for Kosoye Amba-Rass milk samples, while the highest were found for those collected from Nara-Awudarda milk samples, probably due to high mineral enrichment and metal leaching (especially Cd and Pb) from coal deposits. PCA revealed clustering of samples with respect to their geographic origin. Validation of PLS-DA model showed 100% classification efficiency using external validation samples and detected Cd and Cu as trace metal markers. The HQ and CR values were within the safe level; however, the former is close to the alert threshold level for Nara-Awudarda milk samples. Thus, further studies on common foodstuffs, constituting a higher proportion in the local diet, are required in this area to provide a complete risk assessment.

The Influence of Cookware on the Concentration of Trace Metals and Lipid Peroxidation in Pork Muscle

To assess cookware�s influence on the concentration of essential and non-essential trace metals and on the lipid peroxidation process in pork muscle during heat treatment, meat samples were cooked without the addition of oil, salt or spices, at a temperature of 200�C � 2�C for 50 minutes, in pans made of aluminium, ceramic-coated aluminium, brass and stainless steel. Fe, Cu, Zn, Mn, Sn, Ni, Cr, Ti, Al, Pb, Cd and U in samples were subsequently determined by optical emission spectrometry (OES). In order to assess the intensity of lipid peroxidation, peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) were determined by colorimetric methods.

Correlation of Low Birth Weight of Neonates to Placental Levels of Zinc, Copper, Iron, Lipid Peroxidation and Glutathione

This study was conducted to seek association between placental redox (antioxidant/oxidant) parameters and essential metals status (zinc, copper, iron) with birth weight. Placental tissue of pregnant women was collected and levels of zinc, copper and iron were analyzed by Inductively Coupled Plasma-Mass spectrometry. The level of glutathione (GSH) along with the metals was found to markedly decrease in study group, while MDA concentration was significantly higher as compared to control group. Glutathione was found to be positively associated with the levels of zinc and birth weight inspite of negative correlation being established between birth weight and MDA. Placental iron level was indicated to be constructive association with birth weight and was unlikely related with level of MDA. Our findings from the study group supports that damaged antioxidant defence mechanism status is well linked with elevated level of MDA and decreased concentrations of essential metals rendering lower birth weight in neonates.

Assessment of essential and non-essential metals in Ethiopian traditional fermented alcoholic beverages

Evaluation of the levels of essential and non-essential metal concentrations in Ethiopian traditional fermented alcoholic beverages (Tella, Tej, Birz, Korefe, Keribo and Borde) was conducted using atomic absorption spectrophotometer (AAS) after HNO3/H2O2 digestion process. A total of 10 bulk samples were collected randomly from vending houses at five different sub-cities of Addis Ababa, the capital city of Ethiopia (Lideta-Kolfe, Bole-Kirkose, Yeka-Gullele, Arada-Addis Ketema and Akaki-Kaliti-Lafto) and from five nearby towns (Sebeta, Dukem, Sululta, Sendafa, and Burayu) of Oromia Regional State. The considered metals include: Ca, Mg, Fe, Zn, Cd, Cr, Cu, Ni, Pb, Co and Mn to ascertain their levels. With 88–96% recovery Ca, Mg, Fe, Zn, Cu, Cd, Pb and Mn were detected at varying concentrations in the beverages, while Co, Ni and Cr were below detection limits. All the beverages were rich in Ca, Mg and Zn. Among the trace metals found Zn was the first. The levels of the trace metals were generally low, and within statutory safe limits set by World Health Organization (WHO). Mineral concentrations were found to be significantly different among the beverages studied (p &lt; 0.05). The levels of metals in the Ethiopian fermented beverages were found comparable with the reported ones. KEY WORDS: Ethiopian beverages, Traditional beverages, Fermented beverages, Essential elements, Non-essential elements Bull. Chem. Soc. Ethiop. 2017, 31(1), 17-30.DOI: http://dx.doi.org/10.4314/bcse.v31i1.2

The distribution of elements in the body of invasive Chinese mitten crabs (Eriocheir sinensis H. Milne-Edwards, 1853) from Lake Dąbie, Poland

The Chinese mitten crab (Eriocheir sinensis) is an invasive species in the Baltic Sea catchment area. Its numbers in fishery are steadily growing and can potentially become a considerable export product. However, the meat of these crustaceans is known to accumulate contaminants, such as trace elements. Therefore, in this study we examined the content of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, U, Zn in the claws, legs, and carapace of Chinese mitten crabs from Lake Dąbie (south-western catchment area of the Baltic Sea). Concentrations of Mo and U were within the sensitivity limit of the analytical method, and the average concentrations (inmgkg−1dw) of the remaining elements ranged from 0.016 (Cd, claw meat) to 191 (Fe, carapace). The meat had very high concentrations of essential metals (Fe>20, Cu>17, Zn>16, Mn>2, in mgkg−1 dw). The concentrations of Pb and Cd were 5 and 100 times lower than the threshold for foods established by the Commission Regulation (EC) No 1881/2006. The meat of crabs from Lake Dąbie should be safe for consumers and may be a source of elements playing important functions in metabolic processes.

Comparison on Different Qualities of Compost on Possible Efficiencies of Nutrient Accumulation, Heavy Metal Absorption and Growth by Chrysanthemum

Two composts; Compost A (CA) was immature compost and Compost B (CB) was commercial compost, were aim of this study to compare the appropriate of nutrient and heavy metal concentrations in soil, including of amount of heavy metal uptake by chrysanthemum, which were evaluated their characteristics on mixed with commercial soil at 10% and 25% (w/w), respectively. We found that, the highest of essential nutrients and beneficial heavy metal concentrations after combinations were increased in all rates on using of the favorable compost as soil amendment, along with significantly increasing of beneficial heavy metal uptake more than using of immature compost especially in Fe and Mn. Moreover, immature compost at 25% could be used as alternative fertilizer level for cultivation of chrysanthemum due to increased biomass as better than in applying at 10%, and the mature compost was the best improved to the chrysanthemum growth when was applied at 25% and 10% respectively, but found that high risk to develop root growth and to unbalance nutrient of applied immature compost. In my opinion should use at low rate of immature compost to avoid the effecting in the growing period of plant. Furthermore at low rate (10%) of mature compost could be also increased biomass as same as in high rate.

Use of low-calcium cultivars to reduce cadmium uptake and accumulation in edible amaranth (Amaranthus mangostanus L.)

This study aimed to investigate the mechanism of low Cd accumulation in crops using edible amaranth (Amaranthus mangostanus L.) as a model. Fifteen amaranth cultivars were grown in long-term contaminated soil, and the differences in soil Cd mobilization, root uptake, and root-shoot translocation between low- and high-Cd accumulating cultivars were examined. The transport pathways of Cd across the root were further identified in Hoagland nutrient solution using the Ca channel blocker La3+, the ATP inhibitor 2, 4-dinitrophenol (DNP), and a nutrition-deficient culture. Cd concentrations in amaranth cultivars varied about six-fold and showed an elevated trend as the concentration of Ca and Zn increased (p < 0.01), but did not exhibit any correlation with Mg and Fe. The concentrations of essential metals (Ca, Mg, Zn, and Fe) in the rhizosphere of low-Cd cultivars were significantly lower than those of high-Cd cultivars, and decreased with decreasing levels of soluble rhizosphere exudates. These findings indicated that low co-mobilization of Cd with essential metals mediated by root-induced exudates of low-Cd cultivars contributed to its low accumulation in amaranth. Uptake of Cd was inhibited along with Ca by La3+ and DNP, but was promoted by Ca or Fe deficiency treatment. Therefore, the Ca pathway is likely the mode of Cd entry into amaranth roots, although Zn and Fe transporters may also be involved. Low-Ca cultivars exhibited lower Cd uptake capability than high-Ca cultivars. The low translocation efficiency of Cd from root to shoot also contributed to its low content accumulation in edible parts of amaranth.

Concentrations of Some Trace Elements in Vegetables Sold at Maun Market, Botswana

Contamination of vegetables with toxic metals is one of the most important contributing factors to ill health throughout the world, more so because vegetables are considered essential for human health and their consumption is highly recommended by health authorities. The aim of this study was to determine the concentrations of selected essential elements (Fe, Cu, Mn, Mo, Zn) and toxic elements (As, Cd, Cr, Pb) in common vegetables sold for human consumption in supermarkets and open market of Maun village, Botswana. Five vegetables (cabbage, rape, tomatoes, onions and potatoes) were purchased from different selling points, washed with de-ionised water, cut into small pieces and digested with aqua regia on a block digester, following the US. EPA method 200 - 7 and analysed for metal content using Inductively Coupled Plasma - Atomic Emission Spectroscopy (ICP-AES). The results showed that concentrations of essential and toxic metals varied with the type of vegetable and also with the market category (supermarket or street vendor). The highest concentration of essential elements was obtained from cabbage with a Zn concentration of 135.4mg/Kg and the lowest was from onion with a Mo concentration of 1.35mg/Kg. For toxic elements the highest concentration was obtained from rape vegetable with a Pb concentration of 4.73mg/Kg and the lowest from the same vegetable with Cr concentration below the detection limit. Also observed was that leafy vegetables, especially cabbage, had the highest concentrations of most trace metals. It was concluded that vegetables sold in Maun had sufficient levels of essential elements but also some had high concentrations of toxic metals. We thus recommend consumption of vegetables from the studied markets with reduced frequency to avoid metal poisoning.

Root avoidance of toxic metals requires the GeBP-LIKE 4 transcription factor in Arabidopsis thaliana.

Summary Plants reorganize their root architecture to avoid growth into unfavorable regions of the rhizosphere. In a screen based on chimeric repressor gene‐silencing technology, we identified the Arabidopsis thaliana GeBP‐LIKE 4 (GPL4) transcription factor as an inhibitor of root growth that is induced rapidly in root tips in response to cadmium (Cd).We tested the hypothesis that GPL4 functions in the root avoidance of Cd by analyzing root proliferation in split medium, in which only half of the medium contained toxic concentrations of Cd.The wild‐type (WT) plants exhibited root avoidance by inhibiting root growth in the Cd side but increasing root biomass in the control side. By contrast, GPL4‐suppression lines exhibited nearly comparable root growth in the Cd and control sides and accumulated more Cd in the shoots than did the WT. GPL4 suppression also altered the root avoidance of toxic concentrations of other essential metals, modulated the expression of many genes related to oxidative stress, and consistently decreased reactive oxygen species concentrations.We suggest that GPL4 inhibits the growth of roots exposed to toxic metals by modulating reactive oxygen species concentrations, thereby allowing roots to colonize noncontaminated regions of the rhizosphere.