Addition Of CdCl2 Research Articles

Exploring cadmium stress responses in sisal roots: Insights from biochemical and transcriptome analysis.

Sisal is a leaf fiber crop with a high integrated value and a wide range of uses in the application of soil remediation of heavy metal contamination. This study provides a preliminary understanding of how sisal responds to Cd stress and presents a theoretical basis for exploring the potential of sisal in the remediation of Cd-contaminated soils. In this work, the activities of the antioxidant enzymes (SOD, POD, and CAT) of sisal were measured by hydroponics with the addition of CdCl2·2.5H2O and different concentrations of Cd stress. Whole transcriptome sequencing (RNA-Seq) analysis was performed with lllumina sequencing technology, and qRT-PCR was conducted to verify the differential genes. The results obtained were as follows: (1) Short-term low concentration of Cd stress (20 mg/kg) had a transient promotion effect on the growth of sisal roots, but Cd showed a significant inhibitory effect on the growth of sisal roots over time. (2) Under different concentrations of Cd stress, the Cd content in sisal root was greater than that in sisal leaf, and Cd accumulated mainly in sisal roots. (3) With the increase of Cd stress concentration, the antioxidant enzyme catalase activity increased, peroxidase activity showed a decreasing trend, and superoxide dismutase showed a trend of increasing and then decreasing. (4) Transcriptome sequencing analysis detected 123 differentially expressed genes (DEGs), among which 85 genes were up-regulated and 38 genes were down-regulated. The DEGs were mainly concentrated in flavonoid biosynthesis and glutathione metabolism, and both processes had some regulatory effects on the Cd tolerance characteristics of sisal. This study elucidated the physiological, biochemical and transcriptomic responses of sisal under cadmium stress, and provided a theoretical basis for the ecological restoration function of sisal.

Fabrication of Bi2O3/Bismuth Titanates Modified with Metal-Organic Framework-In2S3/CdIn2S4 Materials for Electrocatalytic H2 Production and Its Photoactivity.

Compositional and structural elucidation of the materials is important to know their properties, chemical stability, and electro-photoactivity. The heterojunction electrocatalyst and photocatalyst activity could open a new window for solving the most urgent environmental and energy problems. Here, for the first time, we have designed and fabricated Bi2O3/bismuth titanates modified with MOF-In2S3/CdIn2S4 materials by a stepwise process. The detailed structural elucidation and formation of mixed composite phases were studied in detail. It has been found that the formed composite was efficiently utilized for the electrocatalytic H2 production reaction and the photocatalytic degradation of tetracycline. XRD patterns for the metal-organic framework-In2S3 showed a main compound of MOF, and it was assigned to a MIL-53 MOF phase, with a monoclinic structure. The addition of CdCl2 onto the MOF-In2S3 phase effectively produced a CdIn2S4 flower platform on the MOF rods. The uniform dispersion of the bismuth titanates in MOF-In2S3/CdIn2S4 materials is detected by mapping of elements obtained by dark-field HAADF-STEM. Finally, the predictions of how to integrate experiments and obtain structural results more effectively and their common development in new heterojunctions for electro-/photocatalytic applications are presented.

Surface-Ligand Tuned Reversible Transformations in Aqueous Environments Between CdSe Magic-Size Clusters and Their Precursor Compounds.

That magic-size clusters (MSCs) have their counterpart precursor compounds (PCs) has not been generally accepted by expertise circles. Here, experimental evidence to support this new concept is presented. With aqueous-phase CdSe MSCs as a model system, it is shown that when the MSCs are dispersed in water containing a certain amount of L-cysteine (Cys), the MSCs disappear slowly. Upon the addition of CdCl2 , the MSCs recover. It is proposed that after dispersing, the MSCs transform to their quasi-isomeric, non-absorbing PCs upon Cys addition. In the presence of CdCl2 , the PCs transform back to the MSCs due to Cys elimination. The surface ligand Cys of the MSCs plays a significant role in the reversible transformations. The present study provides compelling evidence that absorbing MSCs have their non-absorbing PCs. The study findings suggest that the transformation between two MSCs that display absorption spectral shifts in a stepwise pattern is assisted by their PCs.

Atomically thin interlayer phase from first principles enables defect-free incommensurate SnO2/CdTe interface

Advancing optoelectronic and emerging technologies increasingly requires control and design of interfaces between dissimilar materials. However, incommensurate interfaces are notoriously defective and rarely benefit from first-principles predictions, because no explicit atomic-structure models exist. Here, we adopt a bulk crystal structure prediction method to the interface geometry and apply it to SnO2/CdTe heterojunctions without and with the addition of CdCl2, a ubiquitous and beneficial, but abstruse processing step in CdTe photovoltaics. Whereas the direct SnO2/CdTe interface is highly defective, we discover a unique two-dimensional CdCl2 interphase, unrelated to the respective bulk structure. It facilitates a seamless transition from the rutile to zincblende lattices and removes defect-states from the interface bandgap. Implementing the predicted interface electronic structure in device simulations, we demonstrate the theoretical feasibility of bufferless oxide-CdTe heterojunction solar cells approaching the Shockley–Queisser limit. Our results highlight the broader potential of designing atomically thin interlayers to enable defect-free incommensurate interfaces.

Enrichment of alliin in different in vitro grown tissues of Allium sativum through CdCl2 elicitation as revealed by high performance thin layer chromatography (HPTLC)

Plant cell tissue and organ culture techniques provide an efficient way for the biosynthesis of high-value secondary metabolites in which elicitation has been recognized to be a potent approach in enriching the bioactive compounds. In this study, an effort was made to assess the influence of Cadmium chloride (CdCl2) on alliin yield of different in vitro grown tissues such as callus, somatic embryos, leaves and roots of Allium sativum. The tissues were cultured in MS amended with various levels of CdCl2 [control (0 mM), T1 (0.05 mM), T2 (0.1 mM), T3 (0.15 mM) and T4 (0.2 mM)] and the yield of alliin was quantified by using high performance thin layer chromatography (HPTLC). Biochemical analyses revealed that sample tissues under increasing CdCl2 conditions accumulated higher levels of sugar, protein and proline with maximum content of sugar (19.61 mg g−1 FW), protein (6.01 mg g−1 FW) and proline (12.19 mg g−1 FW) in leaves at T3 after 4 days of elicitor treatment. Changes within the activities of varied antioxidant enzymes like catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) was assayed as the addition of CdCl2 in the medium causes stress. We noted that with an elevated level of CdCl2, antioxidant enzyme activity increased linearly with the highest activity observed in leaves at T4 of 6 days of elicitation (4.97 EU min−1 mg−1 protein CAT, 6.30 EU min−1 mg−1 protein SOD and 1.125 EU min−1 mg−1 protein APX). Increased activities of enzymes are involved in negating the cellular stress triggered due to the overproduction of ROS. The yield of alliin in response to varying levels of CdCl2 was estimated by using a simple, rapid, and sensitive HPTLC method. The best separation was achieved using butanol:propanol:acetic acid:water (3:1:1:1) as mobile phase. For analysis of alliin, the plates were scanned at 550 nm after spraying with ninhydrin and a good resolution was achieved with Rf value of 0.66. In our study, the alliin yield enhanced in all tested cultures with the elicitor level up to T3. In leaves, maximum accumulation of alliin (3.37 μg g−1 dry wt.) was noted on 0.15 mM (T3) CdCl2 added medium. Our data indicated the increase of alliin in CdCl2 added cultures, which suggests that the use of elicitors as a potential strategy for augmenting secondary metabolite synthesis.

Third-order optical nonlinearity properties of CdCl2-modifed Ge–Sb–S chalcogenide glasses

We developed a new type of chalcohalide glasses with physicochemical and nonlinear optical properties that are tunable by composition. It is found that more than 60 mol.% CdCl2 heavy metal halide can be dissolved into the ternary Ge–Sb–S system and forming stable glasses. The visible-light transparency range is extended to shorter wavelengths with the addition of CdCl2, which is beneficial for the optical quality control and infra-red (IR) system alignment. The third-order optical nonlinearity (TONL) is studied using the femtosecond Z-scan method. The results show that both the nonlinear refractive index and two photon absorption co-efficient decrease with CdCl2. Benefiting from the favorable property-tailoring effects of CdCl2, the TONL figure of merit (FOM) can be improved to meet the requirement (FOM < 1) for all-optical switching and IR photonic applications.

Response of transgenic tobacco overexpressing the CchGLP gene to cadmium and aluminium: phenotypic and microRNAs expression changes.

Transgenic tobacco (N. tabacum cv. Xanthi nc) expressing Capsicum chinenseCchGLP gene that encodes an Mn-SOD, constitutively produces hydrogen peroxide that increase endogenous ROS levels. Previous studies using these plants against geminivirus infections as well as drought stress confirmed that CchGLP expression conferred resistance against biotic and abiotic stresses. Cadmium (Cd) and Aluminium (Al) contamination in soils are a major ecological concern since they are two of themost widespread toxic elements in terrestrial environments. Trying to explore additional possible tolerance to another stresses in these plants, the aim of this work was to analyse the response to cadmium and aluminium salts during germination and early stages of plantlet development and a differential transcriptome of microRNAs (miRNAs) expression in expressing CchGLP transgenic lines and an azygote non-CchGLP expressing line. Plants were grown in vitro with addition of CdCl2 and AlCl3 at three different concentrations: 100, 300 and 500μM and 50, 150 and 300μM, respectively. The results showed higher tolerance to Cd and Al salts evaluated in two CchGLP-expressing transgenic lines L8 and L26 in comparison with the azygous non-CchGLP expressing line L1. Interestingly, L8 under Al stress presented vigorous roots and development of radicular hairs in comparison with azygous control (L1). Differentially expressed miRNAs in the comparison between L8 and L1 were associated with up and down-regulation of target genes related with structural molecule activity and ribosome constituents, as well as down-regulation in proton-transporting V-type ATPase (Vacuolar ATPase or V-ATPase). Moreover, KEGG analysis of the target genes for the differentially expressed miRNAs, led toidentification of genes related with metabolic pathways and biosynthesis of secondary metabolites. One possible explanation of the tolerance to Cd and Al displayed in the transgenic tobaccos evaluated, might involve the fact that several down-regulated miRNAs, were found associated with target genes expressing V-ATPase. Specifically, miR7904-5p was down regulated and related with the up-regulation of one V-ATPase. The expression levels of these genes was confirmed by qRT-PCR assays, thus suggesting that a cation transport activity driven by the V-ATPases-dependent proton motive force, might significantly contribute as one mechanism for Cd and Al detoxification by vacuolar compartmentation in these transgenic tobacco plants.

Chloride-Induced Thickness Control in CdSe Nanoplatelets.

Current colloidal synthesis methods for CdSe nanoplatelets (NPLs) routinely yield samples that emit, in discrete steps, from 460 to 550 nm. A significant challenge lies with obtaining thicker NPLs, to further widen the emission range. This is at present typically achieved via colloidal atomic layer deposition onto CdSe cores, or by synthesizing NPL core/shell structures. Here, we demonstrate a novel reaction scheme, where we start from 4.5 monolayer (ML) NPLs and increase the thickness in a two-step reaction that switches from 2D to 3D growth. The key feature is the enhancement of the growth rate of basal facets by the addition of CdCl2, resulting in a series of nearly monodisperse CdSe NPLs with thicknesses between 5.5 and 8.5 ML. Optical characterization yielded emission peaks from 554 nm up to 625 nm with a line width (fwhm) of 9–13 nm, making them one of the narrowest colloidal nanocrystal emitters currently available in this spectral range. The NPLs maintained a short emission lifetime of 5–11 ns. Finally, due to the increased red shift of the NPL band edge photoluminescence excitation spectra revealed several high-energy peaks. Calculation of the NPL band structure allowed us to identify these excited-state transitions, and spectral shifts are consistent with a significant mixing of light and split-off hole states. Clearly, chloride ions can add a new degree of freedom to the growth of 2D colloidal nanocrystals, yielding new insights into both the NPL synthesis as well as their optoelectronic properties.

Soluble Xanthate Compounds for the Solution Deposition of Metal Sulfide Thin Films

AbstractA series of soluble metal ethylxanthate compounds was synthesised as precursors for metal sulfide thin films to be deposited using solution‐based techniques. Initially, a range of air‐ and moisture‐stable organic ethylxanthate (EtXn) salts were synthesised (cation=Me4N (1), Et4N (2), Pr4N (3), Ph4P (4), guanidinium (5), NMeH3 (6), NMe2H2 (7), NMe3H (8), NH4 (9)). Thermogravimetric analysis (TGA) was used to examine their decomposition profiles, which in turn informed the decision of which counter cation was best suited for inclusion in the metal xanthate compounds. Periodic NMR spectroscopy studies and single‐crystal X‐ray diffraction (SXRD) were used to determine the role protic ammonium counter cations play in the detrimental conversion of xanthates to dithiocarbamate anions. The organic salts 1 and 4 were used to form the metal ethylxanthate compounds (Me4N)[M(EtXn)x] (x=3 for M=Cd (10 Cd), Ni (10 Ni), Zn (10 Zn); x=4 for M=La (11 La)) and (Ph4P)[M(EtXn)3] (M=Cd (12 Cd), Ni (12 Ni), Zn (12 Zn)). Solubility studies on these compounds were performed using a range of solvents to demonstrate the viability of using these compounds for solution‐based deposition methods for thin‐film formation. TGA of the metal xanthate compounds was used to examine their thermal‐decomposition profiles and the product resulting from thermolysis was found to be the respective metal sulfide. In addition, the coproducts of thermal decomposition were analysed by headspace gas‐chromatography mass spectrometry (HS GC–MS) to probe the decomposition mechanism of the precursors. In situ variable‐temperature synchrotron XRD studies on both bulk and thin‐film samples of 10 Cd and 12 Cd were used to examine metal sulfide crystalline phase formation. Decomposition of both precursors was found to give CdS in a hexagonal phase, with the addition of CdCl2 found to aid in increasing the crystallite size during crystallisation.

Development of Treatment Process for Anode Residue from Molten Salt Electrorefining of Spent Metallic Fast Reactor Fuel

A new treatment process was proposed for the anode residue from a molten salt electrorefining step in the pyrometallurgical reprocessing of spent metallic fast reactor fuel. This treatment process consists of two steps: (a) oxidation of the remaining actinides in the anode residue by the addition of CdCl2 and (b) removal of the accompanying chloride by high-temperature distillation. The oxidation of the remaining uranium by CdCl2 was studied using anode residue from previous electrorefining experiments using U-Zr alloys. The reaction between uranium and CdCl2 was completed in [approximately]2 days with a satisfactory chlorine balance among the species in the molten chlorides solvent. A high uranium oxidation rate was attained by appropriately controlling the rate of CdCl2 addition. The high-temperature distillation tests were carried out at 1473 K with pressure of [approximately]300 Pa to remove the solvent accompanying the anode residue. The chloride content in the anode residue was lowered to 1% to 2.5% by the distillation operation. Although the anode residue was heated to 1673 to 1773 K at a pressure of [approximately]50 kPa after the distillation, it was not melted completely. The remaining ratio of uranium after the electrorefining and the above treatment process was evaluated to be 0.04% to 0.20%. Material flow calculations were performed for a pyrometallurgical reprocessing facility equipped with the anode residue treatment process. It showed that (a) the chlorine and uranium supply/demand balance is maintained unless the remaining ratio of uranium after electrorefining exceeds a certain value and (b) the addition of the anode residue treatment process does not have an adverse effect on either the performance of the overall process or the facility design.

Enzyme mediated synthesis of phytochelatin-capped CdS nanocrystals

We reported the enzyme mediated synthesis of CdS nanocrystals by immobilized phytochelatin synthase, which converts glutathione into the metal-binding peptide phytochelatin (PC). Formation of CdS nanocrystals were observed upon the addition of CdCl2 and Na2S with PC as the capping agent. By varying the reaction times, different compositions of PCs (form PC2 to PC3) can be synthesized, resulting in the formation of highly stable nanocrystals with tunable sizes (from 2.0 to 1.6 nm diameter). This approach may be generalized to guide the in vitro self assembly of a wide range of nanocrystals with different compositions and sizes.

Structural and optical properties of CdS nanocrystals grown in water‐soluble diblock copolymer

AbstractMethoxy‐capped poly(ethylene glycol) (PEG) was used to prepare ATRP initiator (PEGBr). PEGBr was copolymerised with t ‐butyl methacrylate (tBMA) by using atom transfer radical polymerization (ATRP) chemistry. tBMA residues were converted to methacrylic acid (MAA) by acidic hydrolysis under mild conditions to give well‐defined PEG–b ‐PMAA diblock copolymers. Near‐monodisperse micellization was observed by the addition of CdCl2 (1.0 wt%) into PEG–b ‐PMAA diblock copolymer solution at pH 11.0 due to complexation of MAA‐ with Cd+2 ions. After addition of thioacetamide into the micellar solution, the Cd+2 cations in the resulting micelles were converted to CdS to obtain CdS nanocrystals in the micelles.The band gap of CdS nanocrystals was obtained from the absorbance measurements in the visible range and found to be 2.4 eV. Electrical resistivity of CdS nanocrystals was found to be 0.21 Ωcm. The thickness of the CdS thin films on glass substrate was found to be 131.14 nm. XRD pattern of CdS nanocrystals has shown that (111), (110), (021), and (220) diffractions are related to the cubic CdS nanocrystals. Preferred crystallographic orientation of the CdS nanocrystals is (110). TEM results have shown that grain sizes of CdS thin films vary between 64 and 133 nm (© 2010 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Phase Behavior of Polystyrene-block-poly(4-vinylpyridine) Copolymers Coordinated by Metal Chloride

The effect of cadmium chloride (CdCl2) on the phase behavior of polystyrene-block-poly(4-vinylpyridine) copolymer (S4VP) was investigated by using rheometry, small-angle X-ray scattering, and transmission electron microscopy. For this purpose, symmetric S4VPs with various molecular weights were prepared by anionic polymerization. We found that with the addition of CdCl2 the order-to-disorder transition of S4VP was significantly increased because of the intermolecular coordination connecting different P4VP block chains. We also studied the change of the domain spacing (D) upon addition of CdCl2 as well as gelation behavior. At a relatively low content of CdCl2 (γ < 6, where γ is the number of coordinated CdCl2 per chain), D remains unchanged. However, when the amount of CdCl2 increases further, D begins to decrease due to many coordinations of CdCl2 that strongly perturb block copolymer conformation, including many ring closures. Furthermore, it is found that the scaled gelation point increases with increa...

Condensation of Nickel–Carbonyl Clusters with Soft Lewis Acids: Synthesis and Characterisation of the {Cd2Cl3[Ni6(CO)12]2}3– Dimer

AbstractReaction of [Ni6(CO)12]2– in thf with 2 equiv. of the softLewis acid CdCl2·2.5H2O gives the new dimeric species {Cd2Cl3[Ni6(CO)12]2}3–. The formation of the latter is not the result of direct addition of CdCl2 to [Ni6(CO)12]2–, but it involves some intermediate species, i.e. [Ni9(CO)18]2– and [Ni9(CO)18Cd2Cl4]2–. The crystal structure of [NBu4]3{Cd2Cl3[Ni6(CO)12]2}·thf was ascertained by X‐ray crystallography. In the solid state, the {Cd2Cl3[Ni6(CO)12]2}3– cluster anions are pillared along the crystallographic c axis, forming infinite columns of perfectly alternating cluster anions and thf molecules. The chemical and electrochemical behaviours of {Cd2Cl3[Ni6(CO)12]2}3– are also reported and compared to those of the parent [Ni6(CO)12]2– dianion.(© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)

Hepatocyte lysis induced by environmental metal toxins may involve apoptotic death signals initiated by mitochondrial injury.

Addition of CdCl2, HgCl2 or K2Cr2O7 to isolated hepatocytes caused a rapid increase in reactive oxygen species ("ROS") formation and a decline in mitochondrial membrane potential. Later lipid peroxidation and cell lysis ensued. Cytotoxicity was prevented by "ROS" scavengers and various inhibitors of the mitochondrial permeability transition (MPT) eg. cyclosporin A, carnitine or trifluoperazine. Antioxidants prevented hepatocyte lysis induced by CdCl2, K2Cr2O7 but not HgCl2. Hepatocyte lysis was also prevented by various apoptosis inhibitors eg, cycloheximide, dactinomycin and a tetrapeptide caspase 3 inhibitor which suggests that metal induced hepatocyte lysis involves apoptotic death signals initiated by MPT and "ROS".

Localization of Fe‐containing superoxide dismutase in cyanobacteria from the Baltic Sea: depth and light dependency

The abundance and cellular location of Fe‐containing superoxide dismutase (Fe‐SOD) in trichomes of Nodularia, Aphanizomenon and Anabaena collected from various depths in the Baltic Sea, and in trichomes of a cultured Nodularia strain, BC Nod‐9427, isolated from the Baltic Sea, was examined by immunogold labelling. For trichomes collected from natural populations the areal concentration of Fe‐SOD labelling decreased with depth: trichomes collected from surface accumulations had between 8 and 11 gold particles μm−2 whereas trichomes collected from a depth of 18 m were unlabelled. When trichomes collected from a depth of 10 m (mean areal labelling density 0·5 gold particles μm−2) were exposed to the higher irradiances present at 1 m, the areal concentration of Fe‐SOD increased to 3·5–4 gold particles μm−2 within 4 h. When cultures of Nodularia strain BC Nod‐9427, adapted to low light (10 μmol m−2 s−1), were transferred to an incident irradiance of 1350 μmol m−2 s−1, a doubling of the areal concentration of Fe‐SOD gold label was observed within 1 h. Addition of 3‐(3,4‐dichlorophenyl)‐1,1′‐dimethylurea (DCMU) to cultures immediately before their transfer to increased illumination resulted in a decrease in areal Fe‐SOD concentrations whereas addition of CdCl2 caused an increase over and above that induced by the elevated irradiance. These results suggest that Baltic Sea cyanobacteria are able to modulate their Fe‐SOD content but that this might be in response to oxidative stress rather than to light per se.

High-level inducible expression of visual pigments in transfected cells.

A method for high-level expression of a functionally active, recombinant human red cone opsin was developed by adding the coding sequence for the C-terminal epitope of bovine rhodopsin onto the C terminus of the cone opsin and cloning the resulting construct into the vector pMEP4 beta. The recombinant pMEP4 beta vector was transfected stably into 293-EBNA cells, and expression of the cone opsin was induced by the addition of CdCl2 into the medium. The recombinant cone opsin was reconstituted with 11-cis retinal and purified by immunoaffinity chromatography. Spectral analysis prior to and following photobleaching confirmed its identity as a red cone opsin. The protein was targeted to the cell membrane and activated bovine transducin.

Human Indoleamine 2,3-Dioxygenase InhibitsToxoplasma gondiiGrowth in Fibroblast Cells

Interferon-gamma (IFN-gamma) is known to inhibit the growth of Toxoplasma gondii both in vivo and in vitro. The IFN-gamma induced anti-toxoplasma activity in human cells is strongly correlated with the degradation of the essential amino acid L-tryptophan in vitro. Destruction of L-tryptophan is due to an increased activity of indoleamine 2,3-dioxygenase (IDO), which is transcriptionally activated by IFN-gamma. To determine if indoleamine 2,3-dioxygenase alone is sufficient to block the T. gondii growth, we transfected human fibroblast cells with an IDO cDNA expression plasmid using a metallothionein-inducible promoter. We showed that IDO mRNA and its enzymatic activity are inducible in fibroblast cells transfected with right-orientation IDO cDNA upon addition of CdCl2 to culture medium. The elevated IDO enzyme activity is strongly correlated with an inhibition of T. gondii growth. No IDO mRNA nor enzyme activity is induced by CdCl2 in reverse orientation transfected cells, and no adverse effects were observed on T. gondii growth in cells transfected with the reverse IDO-construct or in control parent cells with or without supplementation of CdCl2. Our observations along with the recent report by Habara-Ohkubo et al. (Infect. Immun. 61, 1810-1813, 1993) suggest that IFN-gamma-induced antitoxoplasma activity is due at least in part to the activation of IDO gene.

Induction of metallothionein in a human astrocytoma cell line by interleukin‐1 and heavy metals

The effects of cytokines and heavy metals on the expression and localization of metallothioneins (MTs) within U373MG astrocytoma cells were analyzed by using indirect immunofluorescence using a monoclonal anti-MT antibody (MT45). IL-1, CdCl2 (50 microM) or ZnCl2 (500 microM) remarkably augmented intracellular MT levels, whereas IL-6 or 10 microM of ZnCl2 showed no inducing activity. From 24 to 48 h after the addition of CdCl2 or IL-1, immunoreactive MTs were found in the cytoplasm and the nucleus. After 72 h, immunoreactive MTs accumulated in a granular form near the cell surfaces in the presence of CdCl2 (50 microM) or IL-1 plus ZnCl2 (10 microM). However, this accumulation was not observed when only IL-1 was added. Thus, Zn2+ facilitated the appearance of the granular form of immunoreactive MTs at a concentration where they do not induce MTs by themselves.

Factors affecting the determination of total mercury in biological samples by continuous-flow cold vapor atomic absorption spectrophotometry.

The acidic reduction of Hg using a continuous-flow analytical system was evaluated. With 25% SnCl2 as the reductant, characteristic concentrations (sensitivities) of 0.44 microgram/L (open cell) and 0.29 microgram/L (flow-through cell) were obtained using inorganic Hg2+ standards in 1.5% HCl. When CH3Hg+ standards were used, absorption signals were an order of magnitude lower, indicating that Sn(II) is incapable of producing Hg degree from organic Hg in this acidic reduction system. Addition of CdCl2 to the SnCl2 reductant, as suggested by Magos (1) for the reduction of organomercurials under alkaline conditions, was without beneficial effect. Similarly, combining Sn with another reducing agent (hydroxylamine hydrochloride), or a strong alkaline solution (40% NaOH), in the reaction coil of the flow-through system did not significantly enhance the Hg absorption signal for either inorganic or organic Hg. Recovery of Hg from spiked liver homogenates digested at 70-80 degrees C using a HNO3/H2SO4/HCl procedure and stabilized with 0.5 mM K2Cr2O7 was > 85% using either inorganic Hg2+ or CH3Hg+, indicating that this digestion procedure successfully breaks the C-Hg bond to form readily reducible Hg species. Using L-cysteine to stabilize standards of inorganic Hg2+ in HCl caused significant depressions of the Hg absorption signal at L-cysteine concentrations > 0.001% (approximately 0.5 mM); 0.1% L-cysteine caused total suppression of the Hg signal. These results indicate that: (1) acidic reduction of Hg by Sn in this continuous-flow system requires breakdown of organomercurials prior to analysis; (2) tissue digestion using HNO3/H2SO4/HCl followed by the addition of K2Cr2O7 to stabilize Hg2+ achieves this breakdown and allows good recovery of total Hg; and (3) use of L-cysteine to complex and prevent losses of Hg should be avoided in systems using acidic reduction of Hg. Concentrations of endogenous tissue sulfhydryls are generally lower than those associated with depressed absorbance signals during the acidic reduction of Hg.