Addition Of Cd Research Articles

Effects of Cd, Cu and Zn on Ricinus communis L. Growth in single element or co-contaminated soils: Pot experiments

Using biofuel plants to remove metal pollutants is a sustainable approach for phytoremediation. Ricinus communis L. (castor bean) is a bioenergy plant that grows rapidly and has a high biomass; it has been proven to be a potential phytoaccumulator of several metals. Pot experiments with single element or co-contaminated soils were conducted to investigate Cd, Cu and Zn accumulation and their interaction in R. communis L. After growing for four months in soils with the addition of Cd (at rates of 1,5,10,20, and 40mg/kg), Cu (at rates of 50, 100, 200, 400, and 600mg/kg), and Zn (at rates of 100,200,400,600, and 800mg/kg) alone or combined, the dry biomass and the concentrations of Cd, Cu, and Zn in the leaves, stems and roots of the castor bean plants were measured, and the translocation and bioaccumulation factors were calculated. It was found that all of the R. communis grew well and produced high biomass, showing a high tolerance to Cd, Cu and Zn. Our experimental results implied that R. communis showed a high phytoremediation potential for soils contaminated by Cd or Zn while displayed a low uptake of Cu. The copper concentration in R. communis was only slightly influenced by Cd and Zn additions to the soils. The interaction pattern of Cd and Zn showed an antagonistic behavior under low concentrations of the Cd and Zn combined treatment while showed a synergistic behavior under high concentrations of the Cd and Zn combined treatment.

Influence of nano-TiO2 particles on the bioaccumulation of Cd in soybean plants (Glycine max): A possible mechanism for the removal of Cd from the contaminated soil

Phytoremediation is a highly efficient technique for the elimination of trace elements from contaminated soils through the shoots and roots of plants. This study was carried out to investigate the effects of nano-titanium dioxide (TiO2) on Cd uptake by soybean plants. The objective of the present research was to examine the potential to improve the phytoextraction of Cd by the application of nano-TiO2 particles. The results showed that an addition of Cd to the soil significantly decreased plant growth and the biomass, pigment and protein contents. Increases in the proline content and malondialdehyde (MDA) indicate that Cd toxicity stresses the plants. Fourier transform infrared spectroscopy (FTIR) was used to determine variations in functional groups due to the Cd taken up into the shoot and root tissues of plants. An application of nano-TiO2 particles restricts Cd toxicity by increasing the photosynthetic rate and growth parameters of the plants. The uptake of Cd was also increased from 128.5 to 507.6 μg/plant with an increase in the nano-TiO2 concentration from 100 to 300 mg/kg in the soil. The application of nano-TiO2 significantly enhanced Cd uptake in the plants. The results of this study thus demonstrate that an application of nano-TiO2 can increase Cd uptake and minimize Cd stress in soybean plants.

Effect of cadmium and chromium adsorption on the zeta potential of clays

The aim of this study was to evaluate the efficiency of two Tunisian mineral clays to capture chromium(III) and cadmium(II) present in landfills leachate and to understand the corresponding mechanisms of sorption. Kinetic studies, adsorption isotherms, particle size distributions as well as zeta potential evolution with adsorbed amount, and pH were studied. The kinetic study revealed that a pseudo-second-order model agrees with the heavy metals adsorption experimental values for both clays. Negative zeta potential was obtained over the entire studied pH range (3–8) and no isoelectric point was found. Adsorption of Cr(III) had a significant effect on the zeta potential which goes from negative values to positive ones, indicating specific adsorption. Upon the addition of Cd(II), the clay surfaces stayed negatively charged whatever the cadmium concentration.

Cadmium potentiates toxicity of cypermethrin in zebrafish

Co-occurrence of pesticides such as synthetic pyrethroids and metals in aquatic ecosystems raises concerns over their combined ecological effects. Cypermethrin, 1 of the top 5 synthetic pyrethroids in use, has been extensively detected in surface water. Cadmium (Cd) has been recognized as 1 of the most toxic metals and is a common contaminant in the aquatic system. However, little information is available regarding their joint toxicity. In the present study, combined toxicity of cypermethrin and Cd and the underlying mechanisms were investigated. Zebrafish embryos and adults were exposed to the individual contaminant or binary mixtures. Co-exposure to cypermethrin and Cd produced synergistic effects on the occurrence of crooked body, pericardial edema, and noninflation of swim bladder. The addition of Cd significantly potentiated cypermethrin-induced spasms and caused more oxidative stress in zebrafish larvae. Cypermethrin-mediated induction of transcription levels and catalytic activities of cytochrome P450 (CYP) enzyme were significantly down-regulated by Cd in both zebrafish larvae and adults. Chemical analytical data showed that in vitro elimination of cypermethrin by CYP1A1 was inhibited by Cd. The addition of Cd caused an elevation of in vivo cypermethrin residue levels in the mixture-exposed adult zebrafish. These results suggest that the enhanced toxicity of cypermethrin in the presence of Cd results from the inhibitory effects of Cd on CYP-mediated biotransformation of this pesticide. The authors' findings provide a deeper understanding of the mechanistic basis accounting for the joint toxicity of cypermethrin and Cd.

Mycorrhizal Inoculation Affects Pb and Cd Accumulation and Translocation in Pakchoi (Brassica chinensis L.)

Heavy metal (HM) contamination in soils is an environmental issue worldwide that threatens the quality and safety of crops and human health. A greenhouse experiment was carried out to investigate the growth, mycorrhizal colonization, and Pb and Cd accumulation of pakchoi (Brassica chinensis L. cv. Suzhou) in response to inoculation with three arbuscular mycorrhizal (AM) fungi (AMF), Funneliformis mosseae, Glomus versiforme, and Rhizophagus intraradices, aimed at exploring how AMF inoculation affected safe crop production by altering plant-soil interaction. The symbiotic relationship was well established between pakchoi and three AMF inocula even under Pb or Cd stress, where the colonization rates in the roots ranged from 24.5% to 38.5%. Compared with the non-inoculated plants, the shoot biomass of the inoculated plants increased by 8.7%–22.1% and 9.2%–24.3% in Pb and Cd addition treatments, respectively. Both glomalin-related soil protein (GRSP) and polyphosphate concentrations reduced as Pb or Cd concentration increased. Arbuscular mycorrhizal fungi inoculation significantly enhanced total absorbed Pb and Cd (except for a few samples) and increased the distribution ratio (root/shoot) in pakchoi at each Pb or Cd addition level. However, the three inocula significantly decreased Pb concentration in pakchoi shoots by 20.6%–67.5% in Pb addition treatments, and significantly reduced Cd concentration in the shoots of pakchoi in the Cd addition treatments (14.3%–54.1%), compared to the non-inoculated plants. Concentrations of Pb and Cd in the shoots of inoculated pakchois were all below the allowable limits of Chinese Food Safety Standard. The translocation factor of Pb or Cd increased significantly with increasing Pb or Cd addition levels, while there was no significant difference among the three AMF inocula at each metal addition level. Meanwhile, compared with the non-inoculated plants, AMF inocula significantly increased soil pH, electrical conductivity, and Pb or Cd concentrations in soil organic matter in the soils at the highest Pb or Cd dose after harvest of pakchoi, whereas the proportion of bioavailable Pb or Cd fraction declined in the AMF inoculated soil. Our study provided the first evidence that AM fungi colonized the roots of pakchoi and indicated the potential application of AMF in the safe production of vegetables in Pb or Cd contaminated soils.

Large Exciton Energy Shifts by Reversible Surface Exchange in 2D II-VI Nanocrystals.

Reaction of n-octylamine-passivated {CdSe[n-octylamine](0.53±0.06)} quantum belts with anhydrous metal carboxylates M(oleate)2 (M = Cd, Zn) results in a rapid exchange of the L-type amine passivation for Z-type M(oleate)2 passivation. The cadmium-carboxylate derivative is determined to have the composition {CdSe[Cd(oleate)2](0.19±0.02)}. The morphologies and crystal structures of the quantum belts are largely unaffected by the exchange processes. Addition of n-octylamine or oleylamine to the M(oleate)2-passivated quantum belts removes M(oleate)2 and restores the L-type amine passivation. Analogous, reversible surface exchanges are also demonstrated for CdS quantum platelets. The absorption and emission spectra of the quantum belts and platelets are reversibly shifted to lower energy by M(oleate)2 passivation vs amine passivation. The largest shift of 140 meV is observed for the Cd(oleate)2-passivated CdSe quantum belts. These shifts are attributed entirely to changes in the strain states in the Zn(oleate)2-passivated nanocrystals, whereas changes in strain states and confinement dimensions contribute roughly equally to the shifts in the Cd(oleate)2-passivated nanocrystals. Addition of Cd(oleate)2, which electronically couples to the nanocrystal lattices, increases the effective thickness of the belts and platelets by approximately a half of a monolayer, thus increasing the confinement dimension.

Effect of Funneliformis mosseae on the growth, cadmium accumulation and antioxidant activities of Solanum nigrum

Arbuscular mycorrhizal (AM) fungi can promote plant growth and resistance to heavy metal (HM), affect HM bioavailability and uptake by plants, and thus have been considered as the most prominent symbiotic fungi for contribution to phytoremediation. A greenhouse pot experiment was performed to assess the effects of Funneliformis mosseae BGC XJ02 (Fm) on the plant growth, P acquisition, Cd accumulation, phytochelatins (PCs) production and antioxidant activities of Cd-hyperaccumulator Solanum nigrum in different Cd-added soils (0, 5, 10, 20 and 40mgCdkg−1soil). Fm associated with S. nigrum very well, and mycorrhizal colonizations were not influenced by Cd addition. Fm inoculation significantly increased P acquisition, plant growth, Cd concentration and Cd uptake in both shoots and roots of S. nigrum at all Cd levels. The improvement of catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) activities in the leaves of mycorrhizal plants suggested that Fm colonization helped S. nigrum to relieve oxidative damage to biomolecules in Cd-contaminated soil. Moreover, glutathione reductase (GR) activities in the leaves of mycorrhizal plants were elevated (from 17% to 99%) in lower Cd levels (0, 5 and 10mgCdkg−1 soil), but reduced in higher Cd levels (20 and 40mgCdkg−1 soil). The obvious decrease of malonaldehyde (MDA) content in the leaves of mycorrhizal plants displayed that Fm symbiosis significantly enhanced antioxidant activities. In conclusion, Fm symbiosis alleviated Cd phytotoxicity to S. nigrum through the improvement of P acquisition and activities of CAT, POD, APX in mycorrhizal plants, and then improved plant growth and phytoremediation efficiency for Cd-contaminated soil.

Cadmium-Induced Hydrogen Accumulation Is Involved in Cadmium Tolerance in Brassica campestris by Reestablishment of Reduced Glutathione Homeostasis.

Hydrogen gas (H2) was recently proposed as a therapeutic antioxidant and signaling molecule in clinical trials. However, the underlying physiological roles of H2 in plants remain unclear. In the present study, hydrogen-rich water (HRW) was used to characterize the physiological roles of H2 in enhancing the tolerance of Brassica campestris against cadmium (Cd). The results showed that both 50 μM CdCl2 and 50%-saturated HRW induced an increase of endogenous H2 in Brassica campestris seedlings, and HRW alleviated Cd toxicity related to growth inhibition and oxidative damage. Seedlings supplied with HRW exhibited increased root length and reduced lipid peroxidation, similar to plants receiving GSH post-treatment. Additionally, seedlings post-treated with HRW accumulated higher levels of reduced glutathione (GSH) and ascorbic acid (AsA) and showed increased GST and GPX activities in roots. Molecular evidence illustrated that the expression of genes such as GS, GR1 and GR2, which were down-regulated following the addition of Cd, GSH or BSO, could be reversed to varying degrees by the addition of HRW. Based on these results, it could be proposed that H2 might be an important regulator for enhancing the tolerance of Brassica campestris seedlings against Cd, mainly by governing reduced glutathione homeostasis.

Effect of Cd Addition on Microstructure and Properties of Mg-Cd Binary Magnesium Alloy

Abstract The effects of Cd on the microstructure and the mechanical properties of Mg-Cd magnesium alloy were investigated. The Mg-Cd binary magnesium alloy was analyzed by metallograph, XRD, SEM and EDS examinations. The results show that the microstructure of the Mg-Cd magnesium alloy is refined obviously by adding a little amount of Cd. When Cd addition (wt%) is from 0% to 0.7%, the alloy is composed of α -Mg matrix. Cd dissolves in the matrix to form a solid solution, and there is no new phase formed, which contributes to the increase of the impact toughness, Brinell hardness of the experimental alloy by 52.9%, 11.9%, respectively. With the Cd content increasing, the mechanical properties of Mg-Cd magnesium alloy are improved accordingly.

Prion protein and its interactions with metal ions (Cu2+, Zn2+, and Cd2+) and metallothionein 3

The effects of heavy metals (Zn 2+ , Cu 2+ , and/or Cd 2+ ) on Escherichia coli expressing either prion (hPrP C ) or metallothionein 3 (MT-3) brain proteins capable of binding these metals were investigated. The expression of hPrP C or MT-3 in E.coli was confirmed using western-blot and dot-blot methods. After analyzing growth curves, we found that bacteria expressing prion protein better tolerated the presence of Zn 2+ in comparison with wild-type bacteria and bacteria expressing MT-3. The addition of Cd 2+ and Cu 2+ was well tolerated by bacteria expressing MT-3, whereas the bacteria expressing prion protein displayed slower growth when compared to the wild-type. We subsequently determined total content of the MT in bacteria using differential pulsed voltammetry (DPV), and depending on the treatment of the individual metals. MT expression in MT3 transformed cells as well as in control E.coli cells increased at the lowest metal concentration (25 µM), followed by a decrease at higher metal concentrations (50, 75, and 150 µM). The highest increase by Cd 2+ were observed. MT expression pattern in hPrP C transformed cells was different. After application of Cu 2+ an increase in MT expression continued also at higher metal concentrations; and after application of Cd 2+ and Zn 2+ no decrease in MT expression at higher metal concentrations was observed.

Fluorometric determination of cadmium(II) and mercury(II) using nanoclusters consisting of a gold-nickel alloy

A one-pot route has been developed for the preparation of bovine serum albumin-templated nickel-doped bimetallic gold-nickel nanoclusters (BSA-Au-Ni NCs) at a 10:1 M ratio of the precursor salts in a BSA matrix under alkaline conditions. The metal ions are reduced to the metal alloys by BSA. The resulting NCs display strong fluorescence and dual emission with peaks at 405 and 640 nm, respectively, under excitation at 340 nm. Fluorescence is strongly enhanced on addition of Cd(II) ions, but quenched on addition of Hg(II) ions. The findings have been exploited to design a fluorometric method for the separate determination of Cd(II) and Hg(II), respectively. The optimized analytical nanosystem displays relatively good dynamics between enhancement and quenching. Cd(II) and Hg(II) can be quantified in the 0 to 200 and 0 nM to 24 μM, respectively. The limits of detection are ~1.8 nM in both cases, which indicates the highest sensitivity to Cd(II) and Hg(II) ions for a fluorescent probe. This new kind of nanocrystal probe is hardly interfered by a range of commonly encountered metal ions. Its advantages were demonstrated by determining Cd(II) and Hg(II) ions in spiked serum samples.

Lentils Responses to Cadmium Pollution from Animal Manure Compost or Metal Salt

The aim of this study was to evaluate phytoavailability of cadmium to lentils after the application of composted animal manures. In a greenhouse experiment, two lentil (Lens culinaris) cultivars were grown in the soils applied with different levels of Cd from animal manure compost, and compared with Cd applied as cadmium chloride or their combination. Phytotoxicity of Cd was determined as plant growth, Cd accumulation, and the uptake of macronutrients. Addition of Cd significantly reduced plant growth and plant weight as well as plant water content. Phytotoxicity of Cd applied through manure composts was significantly less than the same rate of Cd amended with soluble CdCl2, suggesting the lower potential hazard of composted manure-applied Cd. Plants accumulated substantial amount of Cd in different plant parts. Most of the Cd taken up was retained in roots, and lentil roots had higher concentrations of Cd than the stem. Phytotoxicity of applied Cd in Ziba was significantly greater than that in Zabol cultivar. Cadmium addition especially as metal salt reduced nutrient concentrations in the shoot, and caused more nutrient accumulation in roots, probably due to the inhibition of their translocation to plant shoots. The results of this experiment point to the fact that the Cd source and loading rate are important factors in evaluation of Cd phytoavailability.

Mycorrhizal fungi and earthworms reduce antioxidant enzyme activities in maize and sunflower plants grown in Cd-polluted soils

Changes in plant antioxidant enzymes (AOEs) in response to cadmium (Cd) pollution are an important mechanism for plant growth and tolerance to Cd-induced stress. The main objective of this greenhouse study was to determine the combined influence of earthworm and arbuscular mycorrhiza (AM) fungal inoculation and their interactions with Cd on AOEs and proline accumulation in leaves of two major crops under Cd stress. Maize (Zea mays L.) and sunflower (Helianthus annuus L.) plants were exposed to Cd stress (10 and 20 mg kg−1 soil), inoculated with either earthworm (Lumbricus rubellus L.) or AM fungi (Glomus intraradices and Glomus mosseae species) in a pot experiment for three months. Exposure to Cd decreased shoot dry weights, increased shoot Cd and P concentrations, leaf proline accumulation and the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and polyphenol oxidase (PPO) in both mycorrhizal and non-mycorrhizal plants and both in the presence and absence of earthworms. Inoculation of both model plants with earthworms and AM fungi decreased shoot Cd concentrations and the activity of all AOEs, except PPO. Although earthworm activity enhanced the proline content of sunflower in Cd-polluted soils, the proline level of both plants remained unaffected by AM fungi. AM fungi and earthworms may decrease the activity of AOEs through a decline in shoot Cd toxicity and concentration, confirming that plant inoculation with these soil organisms improves maize and sunflower tolerance and protection against Cd toxicity. Generally, the effect of AM fungal inoculation on plant responses to Cd addition was greater than that of earthworm activity. Nonetheless, the interactive effect of AM fungus and earthworm is of minor importance for most of the plant AOEs in Cd-polluted soils.

Self-assembly of sodium bis(2-ethylhexyl) sulfosuccinate in aqueous solutions: Modulation of micelle structure and interactions by cyclodextrins investigated by small-angle neutron scattering

The modulating effects of α-cyclodextrin (α-CD) and hydroxypropyl β-cyclodextrin (HP-β-CD) on micelles formed in water by the double tail surfactant sodium bis(2-ethylhexyl) sulfosuccinate (also known as dioctyl sulfosuccinate (DOSS) or Aerosol-OT (AOT)) have been investigated using small angle neutron scattering (SANS). SANS data were fitted to the core–shell oblate ellipsoid form factor and Hansen–Hayter-based structure factor in order to quantify the effect of cyclodextrins on the micelle structure and inter-micelle interactions. The results suggested that addition of cyclodextrins caused a sharp decrease in surfactant aggregation numbers, micelle dimensions and micelle charge. The micelle shape changed from elongated oblate to sphere upon addition of cyclodextrin at stoichiometric ratio of 1:1 CD:AOT for HP-β-CD and 2:1 for α-CD. HP-β-CD was found more effective than α-CD in influencing the micelle properties. For example, the decrease in surfactant aggregation number upon addition of 1mM CD at constant total surfactant concentration was about double for HP-β-CD compared to α-CD. The results are consistent with the localization of small amount of cyclodextrins in the micelle, while the remainder stays in the solution pseudophase. The present study offers an improved understanding on the modulating effects of CDs on micelle structure and enables better design of emulsifiers or dispersants in formulations suitable for controlled release of actives.

Effect of Cadmium Addition on the Galvanic Corrosion of AM60 Magnesium Alloy in 0.1 M Sodium Chloride Solution

The corrosion behaviour of AM60 magnesium alloy containing 1.88 wt.% Cd in 0.1 M NaCl solution was investigated by weight loss and hydrogen evolution measurements. The microstructure was evaluated using EPMA. Cd was observed to have an even distribution, hence, no new phase was formed. The corrosion resistance was enhanced by the addition of Cd. The rate of corrosion reduced by a factor of 1.5 times that of AM60 alloy. The microstructure played a crucial role as the presence of defects in the alloys initiated and accelerated corrosion.

A hemicellulose-bound form of silicon inhibits cadmium ion uptake in rice (Oryza sativa) cells.

Silicon (Si) alleviates cadmium (Cd) toxicity in rice (Oryza sativa). However, the chemical mechanisms at the single-cell level are poorly understood. Here, a suspension of rice cells exposed to Cd and/or Si treatments was investigated using a combination of plant cell nutritional, molecular biological, and physical techniques including in situ noninvasive microtest technology (NMT), polymerase chain reaction (PCR), inductively coupled plasma mass spectroscopy (ICP-MS), and atomic force microscopy (AFM) in Kelvin probe mode (KPFM). We found that Si-accumulating cells had a significantly reduced net Cd(2+) influx, compared with that in Si-limited cells. PCR analyses of the expression levels of Cd and Si transporters in rice cells showed that, when the Si concentration in the medium was increased, expression of the Si transporter gene Low silicon rice 1 (Lsi1) was up-regulated, whereas expression of the gene encoding the transporter involved in the transport of Cd, Natural resistance-associated macrophage protein 5 (Nramp5), was down-regulated. ICP-MS results revealed that 64% of the total Si in the cell walls was bound to hemicellulose constituents following the fractionation of the cell walls, and consequently inhibited Cd uptake. Furthermore, AFM in KPFM demonstrated that the heterogeneity of the wall surface potential was higher in cells cultured in the presence of Si than in those cultured in its absence, and was homogenized after the addition of Cd. These results suggest that a hemicellulose-bound form of Si with net negative charges is responsible for inhibition of Cd uptake in rice cells by a mechanism of [Si-hemicellulose matrix]Cd complexation and subsequent co-deposition.

An analytical deterministic model for simultaneous phytoremediation of Ni and Cd from contaminated soils.

Soil contamination by heavy metals, due to human activities, is not often limited to a single contaminant. The objective of this study was to develop a simple model for phytoextracting separate and combined Ni and Cd from contaminated soils. The study was further aimed to study phytoextraction potential of ornamental kale and land cress grown in soils contaminated with separate and combined Ni and Cd metals. The results indicated that elevated Ni and Cd concentrations in soil inhibit growth of both ornamental kale and land cress plants. In Ni + Cd treatments, growth and development of both plants were more affected than in either Ni or Cd treatments. Further, in Ni + Cd treatments, Ni concentration in tissues of both plants was increased by increasing soil Ni concentration under various Cd concentrations. At constant Ni concentration, addition of Cd did not appreciably changed Ni content of plant tissues. Land cress demonstrated higher tolerance to soil contamination by Ni and Cd compared to ornamental kale. It also demonstrated higher phytoextraction potential for soil Cd than ornamental kale. Enhanced bioavailability of Ni and Cd ions, due to competitive adsorption and desorption reactions, had no reasonable effect on metal ion accumulation in plant tissues. This indicates that at relatively high soil contamination, metal ion adsorption is no longer a limiting factor for phytoremediation. The newly proposed model, which assumes that metal uptake rate inversely depends on total soil metal ion concentration, reasonably well predicted the cleanup time of Ni, Cd, and Ni at the presence of Cd from the contaminated soils. The model also predicts that phytoremediation process takes much longer time when soil is contaminated by multi-metal ions.

Mycorrhizal effects on growth, P uptake and Cd tolerance of the host plant vary among different AM fungal species

It has been documented that arbuscular mycorrhizal (AM) symbiosis can enhance plant tolerance to heavy metal (HM) contamination. However, variations among different AM fungal species for their ability to make their host HM tolerant have rarely been examined. This study therefore aimed to compare the cadmium (Cd) tolerance of plants colonized by different AM fungi, and to test the relationship between phosphorus (P) uptake efficiency and the Cd tolerance of the symbiotic associations. Lotus japonicus L. inoculated with each of three different AM fungi, Gigaspora margarita Becker & Hall, Acaulospora longula Spain & Schenck and Rhizophagus irregularis Blaszk., Wubet, Renker & Buscot, was grown under three Cd addition levels (0, 5 and 50 mg kg−1) in a pot experiment, and growth, P and Cd uptake of the plants were examined. Significant linear correlations were observed between growth, P-uptake and Cd-uptake of the plant. R. irregularis was more resistant to Cd contamination compared with the other two AM fungal species in terms of higher colonization rate, P uptake efficiency and better plant growth, even in a Cd contaminated environment. Symbiotic P uptake might determine the Cd tolerance of mycorrhizal plants, and it could possibly serve as an important criterion for screening efficient AM fungal species/strains for bioremediation of HM-contaminated environments.

Self-assembly control via molecular recognition: Effect of cyclodextrins on surfactant micelle structure and interactions determined by SANS

Abstract We report here the modulating effects of α-cyclodextrin (α-CD) and hydroxypropyl β-cyclodextrin (HPβ-CD) on the self-assembly of a common single-tail surfactant, sodium dodecyl sulfate (SDS), in aqueous solutions. Small angle neutron scattering (SANS) data were fitted using core–shell prolate ellipsoid form factor and Hansen–Hayter-based structure factor to quantify the effects of CD type and concentration on the micelle structure and inter-micellar interactions. The presence of cyclodextrins results in decreased micelle aggregation numbers and sizes, and changes the micelle shape from ellipsoid to sphere. Further, the addition of CD reduces inter-micelle interactions through a decrease of electrostatic coupling. CDs affect the micelle properties directly, by localizing in the micelles, as well as indirectly, by driving surfactants away from the micelles into the solution due to complexation. The effect of α-CD on micelle structure is more pronounced at Cα-CD/CSDS >1 compared to the cases when Cα-CD/CSDS

Influence of sulfur and cadmium on antioxidants, phytochelatins and growth in Indian mustard.

Soils in many parts of the world are contaminated with heavy metals, leading to multiple, deleterious effects on plants and threats to world food production efficiency. Cadmium (Cd) is one such metal, being toxic at relatively low concentrations as it is readily absorbed and translocated in plants. Sulfur-rich compounds are critical to the impact of Cd toxicity, enabling plants to increase their cellular defence and/or sequester Cd into vacuoles mediated by phytochelatins (PCs). The influence of sulfur on Cd-induced stress was studied in the hyperaccumulator plant Indian mustard (Brassica juncea) using two sulfur concentrations (+S, 300 µM [Formula: see text] and S-deficient -S, [Formula: see text]) with and without the addition of Cd (100 µM CdCl2) at two different time intervals (7 and 14 days after treatment). Compared with control plants (+S/-Cd), levels of oxidative stress were higher in S-deficient (-S/-Cd) plants, and greatest in S-deficient Cd-treated (-S/+Cd) plants. However, additional S (+S/+Cd) helped plants cope with oxidative stress. Superoxide dismutase emerged as a key player against Cd stress under both -S and +S conditions. The activity of ascorbate peroxidase, glutathione reductase and catalase declined in Cd-treated and S-deficient plants, but was up-regulated in the presence of sulfur. Sulfur deficiency mediated a decrease in ascorbate and glutathione (GSH) content but changes in ascorbate (reduced : oxidized) and GSH (reduced : oxidized) ratios were alleviated by sulfur. Our data clearly indicate that a sulfur pool is needed for synthesis of GSH, non-protein thiols and PCs and is also important for growth. Sulfur-based defence mechanisms and the cellular antioxidant pathway, which are critical for tolerance and growth, collapsed as a result of a decline in the sulfur pool.