Atp7b deficiency induces zebrafish eye developmental defects

As a copper (Cu) transport ATPase, ATP7B plays an important role in maintaining Cu homeostasis in the body and its dysfunction is associated with retinal disease. How ATP7B dysfunction and the subsequent Cu overload induce retinal damage, however, are unknown. Here, we show that atp7b-/- homozygous zebrafish larvae are insensitive to light stimulation, with a reduction in retinal cells but normal like morphological phenotypes. Additionally, a series of differentially expressed genes (DEGs) are unveiled in atp7b-/- mutated larvae, which enrich in photo-transduction, structural constituent of eye lens, sensory perception of light stimulus, oxidative phosphorylation and ATPase activity. Moreover, we show the Cu accumulation in retinal cells in atp7b-/- mutated larvae, which results in ER stress and retinal cell apoptosis and subsequent retinal defects. The integral data in this study demonstrates that atp7b mutation leads to Cu accumulation in zebrafish retinal cells and the consequence ER stress and retinal cell death. These data may give some possible hints to explain retinal disease occurred in the Cu dysregulation syndromes Wilson disease with ATP7B mutation.

Tomato response to metal nanoparticles introduction into the nutrient medium

This study is aimed to explore the capacity of metal nanoparticles (NPs) iron, zinc, copper and their combinations introduced in the Murashige-Skoog (MS) nutrient medium (NM) to affect the growth and development of tomato plants (Solanum lycopersicum L.). NPs were prepared by a flow-levitation method. Metal NPs were characterised by transmission and scanning electron microscopy, X-ray phase analysis. Average NPs diameters were: iron - 27.0 nm, zinc - 54.0 nm, copper - 79.0 nm. MS NM was modified by substitution of common metal sulphates by neutral metal NPs instead of salts. Tomato seedlings cultivation on NM MS with NPs instead of salts assures improved seedling parameters (root length and root activity) in comparison with plants grown on standard MS. Venice cultivar tomato seedlings grown on NM with metal NPs demonstrated an increase in: seed germination by 10-180%, root length by 10-20%, and root activity by 10 -125%. After 45 days of cultivation, tomato seedlings were transplanted in a greenhouse and were grown up to the harvest. Effects in seed germination and increase of crop mass depended on metal nature and NPs concentration.

Enhancement of secondary metabolites in Bacopa monnieri (L.) Pennell plants treated with copper-based nanoparticles in vivo

The study aims to document the effect of starch-stabilised copper-based nanoparticles (CuNPs) on the biosynthesis of pharmaceutically valuable secondary metabolites, especially saponins, of the reputed nootropic herb Bacopa monnieri (L.) Pennell. CuNPs were synthesised chemically by the reduction of cupric sulphate pentahydrate with ascorbic acid using starch as the capping agent. They were characterised by UV-visible spectrophotometry, Fourier-transform infra-red spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy and zeta potential. The nanoparticles consisted of cuprous oxide and metallic copper, were approximately spherical, polydispersed with diameter <20 nm. Hydroponically grown B. monnieri plants were treated in vivo with the CuNPs between the concentrations of 0-100 mg l-1. Spectrophotometric estimation of the total contents of saponins, alkaloids, phenolics, flavonoids and DPPH radical scavenging capacity from the methanolic extracts of the whole plants showed a hormetic increase in the content of secondary metabolites in a concentration-dependent manner from 5 mg l-1 until it declined at toxic metabolic concentration. This was accompanied by an increase in ROS markers hydrogen peroxide and malondialdehyde as well as a hormetic effect on activities of phenylalanine ammonia lyase and antioxidant enzymes catalase, ascorbate peroxidase and superoxide dismutase. CuNPs at sub-toxic concentrations were found to enhance secondary metabolism and antioxidant capacity in Bacopa monnieri through ROS-mediated defence response.

Green synthesis and characterisation of CuNPs: insights into their potential bioactivity

The current investigation involves the green synthesis of copper nanoparticles (CuNPs) from an aqueous plant extract of Moringa oleifera Lam by two methods: (I) time‐based approach and (II) heat treatment of aqueous solution. Prepared CuNPs were characterised via Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy and transmission EM. The study also reveals the potential bioactivity of the prepared CuNPs. In vitro anti‐microbial efficiency of CuNPs was estimated against bacterial and fungal strains by the agar well diffusion method. Anti‐oxidant capacity of CuNPs was determined using ferric reducing ability of plasma (FRAP), lipid peroxidation (LPO) and peroxidase assays, while the antiplatelet potential was determined by measuring two haemostatic parameters (PT & APTT assay). The minimum inhibitory concentration was observed at 60 µg/ml against Streptomyces griseus and Aspergillus niger when NPs were prepared by method II. CuNPs prepared by the method I showed higher FRAP and LPO activities, while increased POX activity was found in CuNPs prepared by method II. CuNPs prepared using method I also showed better anti‐oxidant and antiplatelet potential. It was observed that M. oleifera ‐derived CuNPs exhibits strong anti‐microbial, anti‐oxidant and APTT potential. This indicates potential utilization of green synthesized NPs for various industrial and therapeutic strategies.

Copper nanoflowers as effective antifungal agents for plant pathogenic fungi

Flower-shaped copper nanoparticles were synthesised by a green and ecofriendly chemical reduction approach using copper sulphate and cytyltrimethal ammonium bromide. The UV-vis spectrophotometer analysis showed maximum absorption at about 552 nm, which is specifically reported for copper nanoparticles. The crystal lattice structure of copper nanoflowers was confirmed by X-ray diffraction analysis. Further, the transmission electron microscopic studies revealed the flower shape copper nanoparticles in the size range of 100-500 nm. The stability of thus synthesised copper nanoflowers was assessed by zeta potential analysis, which was found to be 35 mV indicating the most stable nature of nanoflowers. The antifungal activity of these copper nanoflowers was evaluated by Kirby-Bauer disk diffusion method against selected common plant pathogenic fungi. It was found that the chemosynthesised copper nanoflowers demonstrated significant inhibitory activity against the plant pathogenic Aspergillus niger, Fusarium moniliforme, F. culmorum, F. oxysporum and F. tricinctum. The maximum antifungal activity was shown against A. niger followed by F. moniliforme, F. oxysporum and F. tricinctum, whereas the minimum activity was reported against F. culmorum. Similarly, the effect of the copper nanoflowers was also evaluated in combination with commercial antifungal agent (ketoconazole), which demonstrated the enhanced activity of antifungal agent.

Biogenic fabrication of CuNPs, Cu bioconjugates and in vitro assessment of antimicrobial and antioxidant activity

In the present study, the authors synthesised copper nanoparticles (CuNPs) by using extract of Zingiber officinale (ginger) and later the NPs were bioconjugated with nisin, which shows antimicrobial activity against food spoilage microorganisms. CuNPs and its bioconjugate were characterised by ultraviolet-vis spectroscopy, NP tracking analysis, Zetasizer, transmission electron microscopy analysis, X-ray diffraction and Fourier transform infra-red (FTIR) spectroscopy. Zeta potential of CuNPs and its bioconjugate were found to be very stable. They evaluated in vitro efficacy of CuNPs and its bioconjugate against selected food spoilage bacteria: namely, Staphylococcus aureus, Pseudomonas fluorescens, Listeria monocytogenes and fungi including Fusarium moniliforme and Aspergillus niger. Antimicrobial activity of CuNPs was found to be maximum against F. moniliforme (18 mm) and the least activity was noted against L. monocytogenes (13 mm). Antioxidant activity of CuNPs and ginger extract was performed by various methods such as total antioxidant capacity reducing power assay, 1-1-diphenyl-2-picryl-hydrazyl free radical scavenging assay and hydrogen peroxide assay. Antioxidant activity of CuNPs was higher as compared with ginger extract. Hence, CuNPs and its bioconjugate can be used against food spoilage microorganisms.

In vitro germination and biochemical profiling of citrus reticulata in response to green synthesised zinc and copper nanoparticles

Green synthesis of nanoparticles by using plants is an emerging class of nanobiotechnology. It revolutionizes all the fields of nanobiotechnology by synthesizing chemical‐free nanoparticles for various purposes. In the present study, zinc and copper nanoparticles were synthesized by using the white leaves of Allium cepa and further characterized through Zeta analyzer and Scanning electron microscopy. Zeta analyzer elucidated that zinc nanoparticles ranged from 8‐32 nm while copper nanoparticles ranged from 15‐30 nm. Scanning electron microscopy clarified that zinc nanoparticles were irregular while copper nanoparticles were spherical in shape. The effects of green synthesized nanoparticles were evaluated on the germination frequency and biochemical parameters of plant tissues. The nucellus tissues were inoculated on Murashige and Skoog (MS) medium augmented with 30 µg/ml suspension of zinc and copper nanoparticles. Green synthesized nanoparticles enhanced the in vitro germination parameters because of their low toxicity and high efficacy. Significant results were obtained for germination parameters in response to the applications of zinc nanoparticles as compared to copper nanoparticles. These nanoparticles could also induce stress in plantlets by manipulating the endogenous mechanism as a result various defence compounds are produced which have potential in treating various human ailments. Copper nanoparticles showed higher toxicity as compared to zinc nanoparticles and triggered the production of antioxidative enzymes and non‐ enzymatic compounds.

Effects of bimetallic nanoparticles on seed germination frequency and biochemical characterisation of Eruca sativa

In the modern era of science and technology, nanotechnology is becoming popular science field because materials at nanoscale contain improved physical, chemical and biological properties. This study aimed to explore the capacity of bimetallic nanoparticle alloys of silver (Ag), copper (Cu), gold (Au) in different ratios to evaluate the effects on medicinally important plant Eruca sativa. Biochemical parameters of Eruca sativa were studied by applying bimetallic alloy nanoparticles. Seeds of Eruca sativa were germinated on Murashige and Skoog medium with various combinations of nanoparticles suspension employed in concentration of (30 µg/ml). Bimetallic alloys were considered as a stress inducing factor in plants while studying the phytotoxicity. Many secondary metabolites were released because defensive mechanism of plants was active in response to stress. Such secondary metabolites produced in medicinal plants have a great capability in treating the human diseases. In the authors' study, nanoparticles of small size and of high toxicity effect produced more secondary metabolites like total protein content, total flavonoids and total phenolic content.

Seed germination and biochemical profile of Silybum marianum exposed to monometallic and bimetallic alloy nanoparticles

In recent years nanotechnology has become increasingly important in almost every field. The new and improved physical, chemical and biological properties of material at nanoscale have far reaching implications in the fields of science and technology. Nanoparticles' effect on various plant species must be investigated to develop a comprehensive toxicity profile for nanoparticles. The current study strives to evaluate the effects of nine types of metal nanoparticles including monometallic and bimetallic alloy nanoparticles [Ag, Au, Cu, AgCu (1:3), AgCu (3:1), AuCu (1:3), AuCu (3:1), AgAu (1:3), AgAu (3:1)] on seed germination, root and shoot growth and biochemical profile of Silybum marianum plant. Seed germination was greatly affected and increased significantly upon treatment with nanoparticles' suspensions and was recorded highest for Ag nanoparticle suspension. Metal nanoparticles also had a significant effect on the biochemical profile of S. marianum. For the first week, the effect on DPPH, total phenolics content, total flavonoids content, total protein content, peroxidase activity and superoxide dismutase activity was enhanced, but declined as the time progressed. Among the nanoparticles being used, the effect of Ag nanoparticle was mostly enhancing. The results obtained are significant in mapping the effects of different monometallic and bimetallic nanoparticles on medicinal plant species.

Determination of traces of copper and zinc in honeys by the solid phase extraction pre-concentration followed by the flame atomic absorption spectrometry detection

A simple and fast solid phase extraction procedure was developed to pre-concentrate traces of Cu and Zn prior to their determination in honey samples by flame atomic absorption spectrometry. The sample preparation included dissolution of honey samples and the passage (at 20 ml/min) of resulting 10% m/v solutions (100 ml) through Dowex 50W × 8-400 resin beds in order to quantitatively retain Cu and Zn and separate them from the glucose and fructose matrix. Enriched Cu and Zn traces were recovered with 5.0 ml of a 3.0 mol/l HCl solution and quantified by flame atomic absorption spectrometry. The procedure proposed was used to analyze sixty nine commercially available and freshly ripened honey samples coming from the Lower Silesia region (Poland). It enabled to measure Cu and Zn within the range of 0.01-1.42 and 0.03-15.38 μg/g, respectively, with precision better than 4%. Accuracy, assessed on the basis of the recovery test and the comparison of results with those obtained using wet digestion and inductively coupled plasma optical emission spectrometry, was ranged from -4% to +6%. Detection limits of Cu and Zn achieved with this method were 5 and 7 ng/g, respectively.

Comparative acute toxicity of gallium(III), antimony(III), indium(III), cadmium(II), and copper(II) on freshwater swamp shrimp (Macrobrachium nipponense)

BACKGROUND

Acute toxicity testing were carried out the freshwater swamp shrimp, Macrobrachium nipponense, as the model animal for the semiconductor applied metals (gallium, antimony, indium, cadmium, and copper) to evaluate if the species is an suitable experimental animal of pollution in aquatic ecosystem.

RESULTS

The static renewal test method of acute lethal concentrations determination was used, and water temperature was maintained at 24.0 ± 0.5°C. Data of individual metal obtained from acute toxicity tests were determined using probit analysis method. The median lethal concentration (96-h LC50) of gallium, antimony, indium, cadmium, and copper for M. nipponense were estimated as 2.7742, 1.9626, 6.8938, 0.0539, and 0.0313 mg/L, respectively.

CONCLUSIONS

Comparing the toxicity tolerance of M. nipponense with other species which exposed to these metals, it is obviously that the M. nipponense is more sensitive than that of various other aquatic animals.

Hydrogen evolution reaction measurements of dealloyed porous NiCu

: Porous metals are of interest for their high surface area and potential for enhanced catalytic behavior. Electrodeposited NiCu thin films with a range of compositions were electrochemically dealloyed to selectively remove the Cu component. The film structure, composition, and reactivity of these samples were characterized both before and after the dealloying step using scanning electron microscopy, energy-dispersive spectroscopy, and electrochemical measurements. The catalytic behavior of the dealloyed porous Ni samples towards the hydrogen evolution reaction was measured and compared to that of the as-deposited samples. The dealloyed samples were generally more reactive than their as-deposited counterparts at low overpotentials, making the dealloying procedure a promising area of exploration for improved hydrogen evolution catalysts.

Plasma leptin inhibits the response of nucleus of the solitary tract neurons to aortic baroreceptor stimulation

Leptin receptors have been identified within the nucleus of the solitary tract (NTS) and leptin injections into the caudal NTS inhibit the baroreceptor reflex. However, whether plasma leptin alters the discharge of NTS neurons mediating aortic baroreceptor reflex activity is not known. A series of electrophysiological single unit recording experiments was done in the urethane-chloralose anesthetized, paralyzed and artificially ventilated Wistar and Zucker obese rat with either their neuroaxis intact or with mid-collicular transections. Single units in NTS antidromically activated by electrical stimulation of depressor sites in the caudal ventrolateral medulla (CVLM) were found to display a cardiac cycle-related rhythmicity. These units were tested for their responses to stimulation of the aortic depressor nerve (ADN) and intra-carotid injections of leptin (50-200ng/0.1ml). Of 63 single units tested in NTS, 33 were antidromically activated by stimulation of CVLM depressor sites and 18 of these single units responded with a decrease in discharge rate after intracarotid injections of leptin. Thirteen of these leptin responsive neurons (∼72%) were excited by ADN stimulation. Furthermore, the excitatory response of these single units to ADN stimulation was attenuated by about 50% after the intracarotid leptin injection. Intracarotid injections of leptin (200ng/0.1ml) in the Zucker obese rat did not alter the discharge rate of NTS-CVLM projecting neurons. These data suggest that leptin exerts a modulatory effect on brainstem neuronal circuits that control cardiovascular responses elicited during the reflex activation of arterial baroreceptors.

Blood pressure and levels of Fe, Ca, Mg, Zn, Cu, Na and K in the hair of young Bantu men from Tanzania

Mineral imbalance in the body may significantly contribute to the development and course of hypertension. In this paper, blood pressure figures have been linked to the levels of Fe, Ca, Mg, Zn, Cu, Na and K in hair. The research sample was composed of young men (n = 91) aged 13-21, from the town of Mafinga, Iringa District, Tanzania. The data collected included their age, tribal background and weekly diet. Based on body mass index, the participants were categorised into pre-defined subgroups. To examine how the minerals in question affect blood pressure, correlation analysis and multiple ridge regression analysis were performed. Analysis of ridge regression findings for the researched group (n = 91) shows that the minerals under scrutiny account for systolic blood pressure variation in 13 % and in 15 % for diastolic blood pressure variation. After including two additional variables-calendar age and body mass index-in regression analysis, the ultimate coefficient of determination (R (2)) changes for systolic blood pressure and remains the same for diastolic blood pressure (R (2) = 0.194 and R (2) = 0.156, respectively). Nutritional analysis shows that the students included in the study received insufficient calories per day (1,500-2,200 kcal). The group of students with abnormal blood pressure were not aware of their poor health. Research findings may result from progressive environmental changes and poor nutrition in terms of food quantity and quality, which had an impact on the subjects' blood pressure. Hair analysis used to determine mineral content in the body may be an auxiliary tool in identifying the links between factors leading to the development of hypertension.

Attenuation of Zn-induced hyperleptinemia/leptin resistance in Wistar rat after feeding modified poultry egg

BACKGROUND

The prevalence of obesity is increasing exponentially world over. Leptin resistance/hyperleptinemia is attributed to its cause in majority of the obese humans where mutation in genetic component or ob gene has not been found operative. The generation of oxidative stress was suggested as its cause. In our previous study, we have reported that the inclusion of antioxidant enriched modified poultry egg (ME) in diet reversed the ionic imbalance and ameliorated the oxidative stress caused by excessive Zn in diet. In the present study, the efficacy of ME verses conventional egg (CE) was tested on Zn-induced leptin resistance in rat model to ascertain if the supplementation of antioxidants in the form of egg can reverse Zn-induced leptin resistance to leptin sensitive state.

METHODS

Hyperleptinemia was induced in rats by feeding them Zn-supplemented hyperleptinemic diets-I and II (Zn-HL-Diet) for 2 months. Thereafter, half of them were fed either on CE or ME mixed Zn-HL-diets I and II for another two months. The data was analyzed applying one way Anova and Tukey's HSD post hoc test.

RESULTS

The results revealed that food intake, gain in body weight, height and number/unit surface area of intestinal microvillus and serum leptin, glucose, insulin and cortisol were higher in CE and Zn-HL-Diet treated groups; serum Zn, Cu, Mg were higher and Cu and Mg in tissues were lower in them than the control group. In ME treated groups, these parameters were lower and were close to the control group. These changes resulted from the restoration of ionic balance of Zn, Cu and Mg in the blood serum and tissues including liver and hair in ME treated rats.

CONCLUSION

The data suggest that Zn-induced leptin resistance can be attenuated through restoring the ionic balance of Zn, Cu and Mg through inclusion of antioxidants in diet such as these modified eggs. But further clinical studies are required before they are put to use for human consumption.

Synthesis and electrical property of metal/ZnO coaxial nanocables

Ag/ZnO and Cu/ZnO coaxial nanocables were fabricated using AgNO3 or copper foil as source materials by the vapor-liquid-solid process. The coaxial nanocables consist of a crystalline metallic Ag or Cu core and a semiconductor ZnO shell. The evolution of the Ag/ZnO products having different morphologies was investigated by stopping the heating at different temperatures. The diameters of the Ag/ZnO nanocables and the Ag cores could be modulated by changing Ag ratio in the source. The electrical characteristics of the Ag/ZnO contact and the influence of annealing reveal a Schottky diode behavior for a single Ag/ZnO nanocable device. The nanocables with uniform shape and controlled size are expected to provide a new choice in various applications of biological detection, nanothermometer, and photocatalysis.

Different effect of cadmium and copper on H+-ATPase activity in plasma membrane vesicles from Cucumis sativus roots

The effect of heavy metals on plasma membrane (PM) H(+)-ATPase (EC 3.6.3.14) activity in cucumber (Cucumis sativus) roots was studied. The aim of this work was to explain the mechanism of modification of the PM H(+)-ATPase activity in plants subjected to heavy metals. Plants were treated with 10 μM Cd or Cu for 6 d. After 3 d exposure to the heavy metals, some of the plants were transferred to control conditions for a further 3 d (3/3 plants). The activity of PM H(+)-ATPase was found to be increased in plants treated with heavy metals. The highest activity measured as proton transport was observed in 3/3 plants. Estimation of transcript levels of C. sativus PM H(+)-ATPase in roots indicated that the action of Cd, but not Cu, affected the gene expression level. Transcript levels of C. sativus PM H(+)-ATPase (CsHA2, CsHA3, CsHA4, CsHA8, and CsHA9) genes increased in roots treated with Cd. Moreover, Western blot analysis with antibody against phosphothreonine and 14-3-3 protein indicated that increased activity of PM H(+)-ATPase under heavy-metal stress resulted from phosphorylation of the enzyme. It was found that Cu markedly increased the activity of catalase and ascorbate peroxidase and reduced the level of H(2)O(2) in cucumber roots. In contrast, Cd did not affect these parameters. These results indicate that Cd and Cu can, in different ways, lead to modification of PM H(+)-ATPase activity. Additionally, it was observed that treatment of plants with heavy metals led to an increased level of heat-shock proteins in the tissues. This suggests that the plants had started adaptive processes to survive adverse conditions, and increased PM H(+)-ATPase activity could further enhance the repair processes in heavy-metal-stressed plants.

Detection of Cd, Pb, and Cu in non-pretreated natural waters and urine with thiol functionalized mesoporous silica and Nafion composite electrodes

Electrochemical sensors have great potential for environmental monitoring of toxic metal ions in waters due to their portability, field-deployability and excellent detection limits. However, electrochemical sensors employing mercury-free approaches typically suffer from binding competition for metal ions and fouling by organic substances and surfactants in natural waters, making sample pretreatments such as wet ashing necessary. In this work, we have developed mercury-free sensors by coating a composite of thiol self-assembled monolayers on mesoporous supports (SH-SAMMS) and Nafion on glassy-carbon electrodes. With the combined benefit of SH-SAMMS as an outstanding metal preconcentrator and Nafion as an antifouling binder, the sensors could detect 0.5 pp b of Pb and 2.5 pp b of Cd in river water, Hanford groundwater, and seawater with a minimal amount of preconcentration time (few minutes) and without any sample pretreatment. The sensor could also detect 2.5 pp b of Cd, Pb, and Cu simultaneously. The electrodes have long service times and excellent single and inter-electrode reproducibility (5% R.S.D. after 8 consecutive measurements). Unlike SAMMS-carbon paste electrodes, the SAMMS-Nafion electrodes were not fouled in samples containing albumin and successfully detected Cd in human urine. Other potentially confounding factors affecting metal detection at SAMMS-Nafion electrodes were studied, including pH effect, transport resistance of metal ions, and detection interference. With the ability to reliably detect low metal concentration ranges without sample pretreatment and fouling, SAMMS-Nafion composite sensors have the potential to become the next-generation metal analyzers for environmental and bio-monitoring of toxic metals.

Response of plasma membrane H+-ATPase to heavy metal stress in Cucumis sativus roots

The effect of heavy metals on the modification of plasma membrane H(+)-ATPase (EC 3.6.3.14) activity in cucumber roots was studied. In plants stressed for 2 h with 10 microM or 100 microM Cd, Cu or Ni the hydrolytic as well as the transporting activity of H(+)-ATPase in the plasma membranes of root cells was decreased. Transcript levels of Cucumis sativus plasma membrane H(+)-ATPase in roots treated with 10 microM Cd, Cu, or Ni as well as with 100 microM Cu or Ni were similar to the control, indicating that the action of metals did not involve the gene expression level. Only in roots exposed to 100 microM Cd was the level of plasma membrane H(+)-ATPase mRNA markedly decreased. The inhibition of the plasma membrane proton pump caused by 100 microM Cd, Cu and Ni was partially diminished in the presence of cantharidin, a specific inhibitor of protein phosphatases. Western blot analysis with the antibody against phosphothreonine confirmed that decreased activity of plasma membrane H(+)-ATPase under heavy metals resulted from dephosphorylation of the enzyme protein. Taken together, these data strongly indicated that alteration of the enzyme under heavy metal stresses was mainly due to the post-translational modification of its proteins in short-term experiments.

Mitochondrial alterations in livers of Sod1-/- mice fed alcohol

Chronic alcohol consumption induced liver injury in Cu,Zn-superoxide dismutase-deficient mice (Sod1-/-), with extensive centrilobular necrosis and inflammation and a reduction in hepatic ATP content. Mechanisms by which ethanol decreased ATP in these mice remain unclear. We investigated alterations in mitochondria of Sod1-/- mice produced by chronic ethanol treatment. These mitochondria had an increase in State 4 oxygen consumption with succinate and especially with glutamate plus malate compared to mitochondria from pair-fed Sod1-/- mice or mitochondria from wild-type mice fed dextrose or ethanol. This uncoupling was associated with a decrease in ADP/O and respiratory control ratios, a decline in mitochondrial membrane potential, enhanced mitochondrial permeability transition, and decreased aconitase activity. Total thiols and uncoupling protein 2 levels were elevated in the pair-fed Sod1-/- mitochondria, perhaps an adaptive response to oxidant stress. However, no such increases were found with the ethanol-fed Sod1-/- mitochondria, suggesting a failure to develop these adaptations. The mitochondria from the ethanol-fed Sod1-/- mice had elevated levels of cleaved Bax, Bak, Bcl-xl, and adenine nucleotide translocator. Immunoprecipitation studies revealed increased association of Bax and Bak with the adenine nucleotide translocator. ADP-ATP exchange was very low in the ethanol-fed Sod1-/- mitochondria. These results suggest that ethanol treatment of Sod1-/- mice produces uncoupling and a decline in Deltapsi, swelling, increased association of proapoptotic proteins involved in the permeability transition, and decreased adenine nucleotide translocator activity, which may be responsible for the decline in ATP levels and development of necrosis in this model of alcohol-induced liver injury.

Sulfur K-edge X-ray absorption spectroscopy as a probe of ligand-metal bond covalency: metal vs ligand oxidation in copper and nickel dithiolene complexes

A combination of Cu L-edge and S K-edge X-ray absorption data and density functional theory (DFT) calculations has been correlated with 33S electron paramagnetic resonance superhyperfine results to obtain the dipole integral (Is) for the S 1s-->3p transition for the dithiolene ligand maleonitriledithiolate (MNT) in (TBA)2[Cu(MNT)2] (TBA= tetra-n-butylammonium). The results have been combined with the Is of sulfide derived from XPS studies to experimentally obtain a relation between the S 1s-->4p transition energy (which reflects the charge on the S atom, QSmol) and the dipole integral over a large range of QSmol. The results show that, for high charges on S, Is can vary from the previously reported Is values, calculated using data over a limited range of QSmol. A combination of S K-edge and Cu K- and L-edge X-ray absorption data and DFT calculations has been used to investigate the one-electron oxidation of [Cu(MNT)2]2- and [Ni(MNT)2]2-. The conversion of [Cu(MNT)2]2- to [Cu(MNT)2]- results in a large change in the charge on the Cu atom in the molecule (QCumol) and is consistent with a metal-based oxidation. This is accompanied by extensive charge donation from the ligands to compensate the high charge on the Cu in [Cu(MNT)2]- based on the increased S K-edge and decreased Cu L-edge intensity, respectively. In contrast, the oxidation of [Ni(MNT)2]2- to [Ni(MNT)2]- results in a small change in QNimol, indicating a ligand-based oxidation consistent with oxidation of a molecular orbital, psiSOMO (singly occupied molecular orbital), with predominant ligand character.

Nitrogen ligands at the active site of alkaline phosphatase

The two Zn(II) ions of native Escherichia coli alkaline phosphatase (EC 3.1.3.1) that are necessary for activity have been replaced by (63)Cu(II). Titration of apoenzyme with up to 2 eq of Cu(II) gives a homogeneous species with an electron spin resonance typical for Cu(II) in an axially symmetric environment, with A(z) = 496 MHz, g(z) = g = 2.27, and g(x) = g(y) = 2.05. At least seven nitrogen hyperfine lines, spaced 11 G apart, are clearly resolved on the M = +[unk] Cu(II) hyperfine peak in the parallel region. When more than 2 eq of Cu(II) are added, the electron spin resonance spectrum shows at least two types of Cu(II) binding sites; the additional site, or sites, are characterized by lower g and higher A(z) values. When Cu(II) is added to native Zn(II) alkaline phosphatase or to apoenzyme incubated with 2 eq of Zn(II), the electron spin resonance spectrum shows little or no trace of the species with higher g values and nitrogen splitting. These results indicate that the species with higher g represents copper bound at the site normally occupied by the 2 Zn (II) ions necessary for enzyme activity, and that the metal ion at this site has at least 3 equivalent nitrogen ligands, probably histidyl side chains.