Time Related Influence of α-Mercapto-β-(2-Furyl) Acrylic Acid (MFA) in Cadmium Toxicity

The effect of a-mercapto-β-(2-furyl) acrylic acid (MFA, 200 mg/kg, oral) administered 30 min or 24 h post cadmium (1 mg/kg, i.p.) exposure on cadmium toxicity, was investigated in rats. The Cd induced hepatic metallothionein was reduced by MFA treatment parallel to the depletion of hepatic Cd. However, in renal tissue,MFA caused only redistribution of metal from the paniculate to the soluble fraction. Hepatic and renal Zn and renal Cu were significantly increased on Cd exposure. MFA therapy, however, lowered the hepatic Zn and increased the renal Cu levels. The action of MFA appears to be via metal chelation rather than by MT induction.

Effect of Nitric Oxide on Alleviating Cadmium Toxicity in Rice (Oryza sativa L.)

Nitric oxide （NO） is a gaseous signaling molecule in plants that plays a key role in mediating a wide range of physiological processes and responses to biotic and abiotic stresses. The present study was conducted to investigate the effects of the exogenous application of sodium nitroprusside （SNP）, an NO donor, on cadmium （Cd）-induced oxidative stress and Cd uptake in rice plants. Rice plants were exposed to Cd stress （0.2 mmol L^-1 CdC12） and different concentrations of SNP （0.05, 0.1, 0.2, and 0.4 mmol L^-1）. A SNP concentration of 0.1 mmol L^-1 （SNP 10） significantly reduced the Cd-induced decrease in shoot and root dry weights and leaf chlorophyll concentrations. The addition of NO also reduced the malondialdehyde （MDA）, hydrogen peroxide （H202） and ascorbic acid （ASA） concentrations. However, the reduction in glutathione （GSH） concentration was inhibited by NO treatment. Moreover, NO prevented the Cd-induced increase in antioxidative enzyme activity. The amount of Cd accumulation in rice plants was also influenced by the addition of NO. The NO supplied by the SNP enhanced the Cd tolerance of the rice by increasing the Cd uptake by the roots and decreasing the Cd accumulation by the shoots. However, the application of potassium ferrocyanide （Cd＋Fe） or sodium nitrate and nitrite （Cd＋N） （without NO release）, did not exhibit the effects of the SNP. Furthermore, the effects of the SNP were reversed by the addition of hemoglobin （an NO scavenger）. Our results suggested that exogenous NO was involved in the resistance of rice to Cd-toxicity.

Alleviation of Cadmium Toxicity to Medicago Truncatula by AMF Involves the Changes of Cd Speciation in Rhizosphere Soil and Subcellular Distribution

Arbuscular mycorrhizal fungi(AMF)can improve plant tolerance to several abiotic stresses,including heavy metals,drought or salinity exposure.However,the role of AMF in alleviation of soil cadmium(Cd)-induced toxicity to plants is still largely unknown.In this study,Cd speciation in soil and subcellular distribution of Cd were used to characterize the roles of application AM fungi in the alleviation of Cd toxicity in alfalfa plants.Our results showed that the addition of Glomus mosseae in Cd contaminated soil(10 mg/Kg)significantly increased soil pH,cation exchange capacity(CEC)and organic matter in rhizosphere soil with Medicago truncatula L.,and then account for significantly decreased contents of exchangeable and carbonate-bounded Cd speciation in rhizosphere soil,indicating alleviation of plant toxicity by reduction of bioavailable fractions of Cd.Although there is no significant difference found in Cd accumulation by roots and shoots respectively between Cd and AM-Cd treatments,more portion of Cd was recorded compartmentalization in cell wall fraction of both root and shoot in treatment of Cd with AM application,indicating alleviation of Cd toxicity to plant cell.Herein,application of AM fungi in Cd treatments performed to inhibit the appearance of Cd toxicity symptoms,including the improvement of leaf electrolyte leakage,root elongation,seedling growth and biomass.This information provides a clearer understanding of detoxification strategy of AM fungi on Cd behavior with development and stabilization of soil structure and subcellular distribution of plant.

Effect of Anions on Toxicity of Cadmium Applied to Microbial Biomass in Red Soil

A laboratory incubation experiment was conducted to elucidate the effects of associated anions on toxicity of cadmium applied to microbial biomass in the red soil. Cadmium was applied at six different levels, i.e., 0 (background), 5, 15, 30, 60 and 100 μg-1 soil in the form of either cadmium acetate or cadmium chloride.Application of cadmium as cadmium acetate markedly reduced the soil microbial biomass carbon compared to cadmium applied as cadmium chloride at all the tested levels. Similarly, organic carbon to biomass carbon ratio in the soil was markedly increased by increasing the level of the cadmium in the soil as cadmium acetate,while the change was much smaller in the case of cadmium chloride at the same cadmium levels. The results suggested that due consideration should be given to the source of cadmium while deciding the cadmium levels in experiments.

Transcription factor OsWRKY72 is involved in Cu/Cd toxicity by regulating lignin synthesis in rice

Maintenance of ion homeostasis in plant cells is an essential physiological requirement for sustainable growth,development,and yield of crops.Plants respond to high levels of heavy metals such as copper(Cu)and cadmium(Cd)to avoid irreversible damage at the structural,physiological and molecular levels.Our previous study found that rice germin-like proteins(OsGLPs)are a type of Cu-responsive proteins.The deletion of 10 tandem OsGLP genes on chromosome 8 led to more severe heavy metal toxicity in rice.In this study,we show that rice WRKY transcription factor OsWRKY72 negatively regulates OsGLP8-7transcription.Overexpression of OsWRKY72 weakens the Cu/Cd tolerance of rice when exposed to Cu and Cd.OsWRKY72 suppressed expression of OsGLP8-7 and lignin synthesis genes,resulting in reduced lignin polymerization and consequently lower lignin accumulation in cell walls,thereby increasing the Cu and Cd accumulation.In addition,OsWRKY53 bound to OsWRKY72 to alleviate the transcriptional inhibition of OsGLP8-7.These results revealed that OsWRKY72-OsGLP8-7 is an important module response of rice to heavy metal stress,and that transcription factor OsWRKY72 acts upstream of OsGLP8-7 to regulate Cu/Cd toxicity.

Modeling of acute cadmium toxicity in solution to barley root elongation using biotic ligand model theory

Protons（H^＋）as well as different major and trace elements may inhibit cadmium（Cd）uptake in aquatic organisms and thus alleviate Cd toxicity.However,little is known about such interactions in soil organisms.In this study,the independent effects of the cations calcium（Ca^2＋）,magnesium（Mg^2＋）,potassium（K^＋）,H^＋ and zinc（Zn^2＋）on Cd toxicity were investigated with 5-day long barley root elongation tests in nutrient solutions.The tested concentrations of selected cations and trace metal ions were based on the ranges that occur naturally in soil pore water.The toxicity of Cd decreased with increasing activity of Ca^2＋,Mg^2＋,H^＋and Zn^2＋,but not K^＋.Accordingly,conditional binding constants were obtained for the binding of Cd^2＋,Ca^2＋,Mg^2＋,H^＋,and Zn^2＋ with the binding ligand：log K（CdBL）5.19,logK（CaBL）2.87,logK（MgBL）2.98,logK（HBL）5.13 and logK（ZnBL）5.42,respectively.Furthermore,it was calculated that on average 29% of the biotic ligand sites needed to be occupied by Cd to induce a 50% decrease in root elongation.Using the estimated constants,a biotic ligand model was successfully developed to predict the Cd toxicity to barley root elongation as a function of solution characteristics.The feasibility and accuracy of its application for predicting Cd toxicity in soils were discussed.

Role of Organic Amendments to Mitigate Cd Toxicity and Its Assimilation in Triticum aestivum L.

In soil biota,higher and enduring concentration of heavy metals like cadmium(Cd)is hazardous and associated with great loss in growth,yield,and quality parameters of most of the crop plants.Recently,in-situ applications of eco-friendly stabilizing agents in the form of organic modifications have been utilized to mitigate the adverse effects of Cd-toxicity.This controlled experiment was laid down to appraise the imprints of various applied organic amendments namely poultry manure(PM),farmyard manure(FYM),and sugarcane press mud(PS)to immobilize Cd in polluted soil.Moreover,phytoavailability of Cd in wheat was also accessed under an alkaline environment.Results revealed that the addition of FYM(5–10 ton ha^(-1))in Cd-contaminated soil significantly increased germination rate,leaf chlorophyll content,plant height,spike length,biological and grain yield amongst all applied organic amendments.Moreover,the addition of FYM(5–10 ton ha^(-1))also reduced the phytoavailability of Cd by 73–85%in the roots,57–83%in the shoots,and 81–90%in grains of wheat crop.Thus,it is affirmed that incorporation of FYM(5–10 ton ha^(-1))performed better to enhance wheat growth and yield by remediating Cd.Thus,the application of FYM(5–10 ton ha^(-1))reduced the toxicity induced by Cd to plants by declining its uptake and translocation as compared to all other applied organic amendments to immobilize Cd under sandy alkaline polluted soil.

Influences of Chloropazine, Nimodipine and Their Combination on the Toxic Effects of Cadmium in Liver and Kidney of Mice

The influences of the calmodulin antagonist chlorpromazine (CPZ), and calcium channel blocker nimodipine (NIMO) and their combination on cadmium (Cd) poisoning of mice were studied. A seties of biochemical parameters including urinary enzyme activities, blood and urine Cd levels, metallothionein (MT) contents in liver and kidney, hepatic ultrastructure and Ca2+ -Mg2+ AT-Pase activity in erythrocyte membrane were determined. Animal models for Cd poisoning were established by peritoneal injection of 1/5 LD50 CdCl2. The experimental groups were protected by administration of CPZ, NIMO and CPZ and NIMO in combination l h before the injection of CdCl2. Five days later, samples were collected for analysis. The data showed that Crs could protect kidney tissue against Cd-induced damage, as the urinary γ-glutamyl traspepti dase (γ- GT ) and N- acetyl-β-D-glucosaminidase (NAG) activities were reduced significantly. There was neither evidence of the protective effect of NIMO on kidney tissue nor an indication of a synergistic effecf of Crs and NIMO.Both CPZ and NIMO showed a considerable protective effect against the deerease in Ca2+ -Mg2+ AT-Pase activity, and a synergistic action was observed. Cd content in blood was reduced significanily by CPZ or the combination of CPZ and NIMO, but elevated by NIMO. Both CPZ and NIMO consideraby increased MT contents in livers and kidneys and ameliorated damaged to the hepatic ultrastructures caused by Cd. The results indicated that these inhibitors could protect mice against the toxic effects of Cd in liver and kidney tissues, while CPZ was more efficient than NIMO. The combination of CPZ and NIMO exerted a synergistic action. The protective action of these two drugs might be relevent to the function of MT.

A Syndrome of Vitamin D3 Deficiency/Fibromyalgia/Hyperparathyroidism Mimicking Rheumatoid Arthritis, a Clinical Prospective Study

Objectives: Rheumatoid arthritis is sometimes misdiagnosed for other diseases, like psoriatic arthritis, erosive OA, viral arthritis, reactive arthritis, IBD arthritis, Lyme’s disease, and palindromic rheumatism. Secondary hyperparathyroidism was not included in the differential diagnosis of RA, though it sometimes presents with joint pains and tenderness, and even arthritis. Fibromyalgia is a psychosomatic disorder characterized by chronic widespread pain and tender areas. Mimicry of some manifestations of these diseases sometimes results in misdiagnosis as RA. Methods: Two hundred patients previously diagnosed as RA from outpatient clinics in Al-Azhar Faculty of Medicine, attended as not responding to medical treatment of RA. All patients were subjected to a re-evaluation of disease activity including HAQ, and DAS 28, CDAI, and SDAI. Also, we measured serum vitamin D3, PTH, total and ionized Calcium, Phosphorus, Uric acid, ACPA, and other routine lab. All patients were exposed to various radiological imaging modalities. Results: Cases not responding to RA treatment were reevaluated and were found to have a syndrome of fibromyalgia associated with vitamin D3 deficiency and secondary hyperparathyroidism. Conclusions: Fibromyalgia/Hyperparathyroidism syndrome is an underdiagnosed disease, which results from chronic vitamin D3 deficiency. SHPT can cause bone erosions, which are mostly shaggy in appearance and distributed in the radiocarpal, radioulnar, metacarpophalangeal and distal interphalangeal joints, in contrast to that which predominate proximal IP joints of rheumatoid arthritis. Radiology of FM/HPT syndrome patients revealed a sign of spur-like excrescences in terminal finger tufts unilaterally or bilaterally, which we think is pathognomonic.

Anionic polyacrylamide alleviates cadmium inhibition on anaerobic digestion of waste activated sludge

The uncontrolled discharge of industrial wastewater leads to a significant cadmium(Cd)accumulation in waste activated sludge(WAS),posing a serious threat to the steady operation of the anaerobic digestion(AD)system in wastewater treatment plants(WWTPs).Therefore,developing a viable approach to cope with the adverse effects of high-concentration Cd on the AD system is urgently required.This study aims to investigate the potential of using anionic polyacrylamide(APAM),a commonly used agent in WWTPs,to mitigate the adverse effects of Cd in a toxic amount(i.e.,5.0 mg per g total suspended solids(TSS))on AD of WAS.The results showed that the effectiveness of higher APAM on Cd toxicity alleviation was less than that of lower APAM at the studied level(i.e.,the effectiveness order was 1.5 mg APAM per g TSS>3.0 mg APAM per g TSS>6.0 mg APAM per g TSS).The moderate supplement of APAM(i.e.,1.5 mg per g TSS)recovered the accumulative methane yield from 190.5±3.6 to 228.9±4.1 mL per g volatile solids by promoting solubilization,hydrolysis,and acidification processes related to methane production.The application of APAM also increased the abundance of key microbes in the AD system,especially Methanolinea among methanogens and Caldilineaceae among hydrolyzers.Furthermore,APAM facilitated the key enzyme activities involved in AD processes and reduced reactive oxygen species(induced by Cd)production via adsorption/enmeshment of Cd by APAM.These findings demonstrate the feasibility of using moderate APAM to mitigate Cd toxicity during AD,providing a promising solution for controlling Cd or other heavy metal toxicity in WWTPs.

Effect of Silicon on Growth, Physiology, and Cadmium Translocation of Tobacco (Nicotiana tabacum L.) in Cadmium-Contaminated Soil

Silicon （Si） offers beneficial effect on plants under cadmium （Cd） stress such as promoting plant growth and increasing resistance to heavy metal toxicity. In this study, a pot experiment was performed to study the role of Si in alleviating Cd toxicity in tobacco （Nicotiana tabacurn L.） plants on a yellow soil taken from Guiyang, China. Nine treatments consisting of three concentrations of Cd （0, 1, and 5 mg kg^-1） together with three Si levels （0, 1, and 4 g kg^-1） were established. Plant growth parameters, Cd concentration, and the malondialdehyde （MDA）, chlorophyll, and carotenoid contents were determined 100 d after transplanting of tobacco seedlings. Application of exogenous Si enhanced the growth of tobacco plants under Cd stress. When 5 mg kg^-1 Cd was added, Si addition at 1 and 4 g kg^-1 increased root, stem, and leaf biomass by 26.1%-43.3%, 33.7% 43.8%, and 50.8% 69.9%, respectively, compared to $i addition at 0 g kg^-1. With Si application, the transfer factor of Cd in tobacco from root to shoot under both 1 and 5 mg kg^-1 Cd treatments decreased by 21%. The MDA contents in the Si-treated tobacco plants declined by 5.5% 17.1% compared to those in the non-Si-treated plants, indicating a higher Cd tolerance. Silicon application also increased the chlorophyll and carotenoid contents by 33.9% 41% and 25.8%-47.3% compared to the Cd only treatments. Therefore, it could be concluded that Si application can alleviate Cd toxicity to tobacco by decreasing Cd partitioning in the shoots and MDA levels and by increasing chlorophyll and carotenoid contents, thereby contributing to lowering the potential health risks of Cd contamination.

Cadmium pollution from phosphate fertilizers in arable soils and crops:an overview

The application of mineral and organic phosphorus fertilizers to arable land has greatly increased crop yield to meet the world food demand.On the other hand,impurities in these fertilizers,such as heavy metals,are being added to agricultural soils,resulting both from the raw materials themselves and the processes used to obtain the final product.Cadmium,a non-essential and toxic heavy metal,has been found in relatively high amounts in common P fertilizers obtained from sediments.This metal poses a high risk for soil fertility,crop cultivation,and plants in general.Furthermore,human health might be compromised by the cadmium concentrations in agricultural and livestock products,due to the bioaccumulation effect in the food web.The accumulation in the different matrixes is the result of the high mobility and flexible availability of this harmful metal.This review summarizes risks to human health,the factors influencing cadmium movement in soils and crop uptake,as well as common plant responses to its toxicity.In addition,it summarizes cadmium balances in soils,trends,long-term experiments,and further studies.Cadmium inputs and outputs in arable soil,together with their calculated concentrations,are compared between two different regions:the European countries(in particular Germany)and China.The comparison appears useful because of the different proportions in the inputs and outputs of cadmium,and the diverse geographical,environmental and social factors.Moreover,these variables and their influences on cadmium contamination improve the understanding of the pollution from phosphate fertilizers and will help to establish future mitigation policies.

An eukaryotic translation initiation factor, AteIF_5A-2,affects cadmium accumulation and sensitivity in Arabidopsis

Cadmium (Cd) is one of the most toxic elements and can be accumulated in plants easily; meanwhile, eIF5A is a highly conserved protein in all eukaryotic organisms. The present work tried to investigate whether eIF5A is involved in Cd accumulation and sensitivity in Arabidopsis (Arabidopsis thaliana L.) by comparing the wild-type Columbia-0 (Col-0) with a knockdown mutant of AteIF5A-2, fbr12-3 under Cd stress conditions. The results showed that the mutant fbr12-3 accumulated more Cd in roots and shoots and had significantly lower chlorophyll content, shorter root length, and smaller biomass, suggesting that downregulation of AteIF5A-2 makes the mutant more Cd sensitive. Real-time polymerase chain reaction revealed that the expressions of metal transporters involved in Cd uptake and translocation including IRT1, ZIP1, AtNramp3, and AtHMA4 were significantly increased but the expressions of PCS1 and PCS2 related to Cd detoxification were decreased notably in fbr12-3 compared with Col-0. As a result, an increase in MDA and H2O2 content but decrease in root trolox, glutathione and proline content under Cd stress was observed, indicating that a severer oxidative stress occurs in the mutant. All these results demonstrated for the first time that AteIF5A influences Cd sensitivity by affecting Cd uptake, accumulation, and detoxification in Arabidopsis.

Cadmium-induced oxidative damage and antioxidant defense mechanisms in Glycine max L.

Objective:To analyze the effect of Cadmium(Cd)on the metabolism of reduced glutathione(GSH)in roots and leaves of Glycine max L.Methods:A capillary electrophoresis methodology was optimized to determinate simultaneously GSH and reduced and oxidized GSH in a precise and accurate way.The functional role of the genes involved in GSH cellular metabolism(γ-glutamylcysteine synthetase),GSH synthetase and glutathione reductase(GR)was evaluated.Finally,the activities of antioxidant enzymes as GR and superoxide dismutases were determinate.Results:The studies ofγ-glutamylcysteine synthetase and GSH synthetase gene expression showed an increase and GR showed a decrease in Cd-treated plants.GR and superoxide dismutases activities increased at 24 h and 6 h respectively in roots under Cd exposure.GSH content was higher and showed a significant increase in roots and leaves at 6 h and 24 h of treatment.Conclusions:The results of the present study showed a better understanding in signaling pathway by alterations in antioxidant mechanisms by Cd in soybean seedlings.

Evaluating the Efficiency of Cadmium Removal by Alginate Hydrogels from Water Using 5,7-Dibromo-8-hydroxyquinoline as a Complexing Reagent

Cadmium toxicity in wastewater is a rising concern due to industries like batteries,metallurgy,electroplating,plastic stabilizers,and pigments.The quantitative detection of Cd^(2+)and its remediation from wastewater samples are of major concern from an environmental point of view.In the present work,an effective spectrophotometric method has been reported using 5,7-dibromo-8-hydroxyquinoline(DBHQ)as a complexing agent for Cd^(2+).This method has advantages like using recyclable,less toxic solvents and easy sample preparation.The limit of detection,limit of quantification,and sensitivity of the proposed method were found to be 33.30,36.70 mg L^(−1),and 2×10^(−3),respectively.The DBHQ method was validated using atomic absorption spectroscopy,and the recovery percentage was more than 98%.These results indicate that DBHQ can be effectively used for monitoring Cd^(2+)in aqueous systems.The method developed was further employed for monitoring Cd^(2+)adsorption on calcium alginate(AL)hydrogels.Batch adsorption studies were done to optimize parameters of Cd^(2+)removal using AL hydrogels,and the data obtained were used for kinetic and thermodynamic studies.Kinetic studies indicated that the pseudo-first-order model showed better fitting,and thermodynamic studies showed Freundlich-like adsorption.The maximum adsorption capacity of Cd^(2+)on AL hydrogels was found to be 56.45 mg g^(−1).The validation studies of DBHQ were performed using statistical analysis methods like t-tests and one-way variance.