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1.
Anna Winiarska-Mieczan 《Biological trace element research》2014,157(1):36-44
Mother's milk is the fundamental food for infants. It contains proteins, fat, carbohydrates and essential metals which are necessary to ensure correct functioning of the organism. Unfortunately, breast milk is a potential source of toxic metals, which are dangerous for a baby. In Poland, previous research concerning the content of metals in breast milk was very scarce or its results were unavailable. The present study aimed at assessing the content of Cd, Pb, Cu and Zn in human breast milk, as well as estimating the mean weekly intake of these metals by breast-fed infants from Poland. The average concentrations of Cd, Pb, Cu and Zn were 2.114 μg/l, 6.331 μg/l, 0.137 mg/l and 1.623 mg/l, respectively. The admissible levels of supply of these toxic metals has not been exceeded, but their contents were high, particularly in 6-month-old infants (nearly 85 % TWI for Cd and nearly 70 % BMDL01 for Pb). The daily intake of Cu and Zn did not fully satisfy the infant's requirements determined by Polish standards and WHO recommendations. Since the lifestyle of lactating women has a direct influence on the content of these elements in breast milk, women should be educated in this respect with particular focus on eliminating tobacco smoking, both by breastfeeding mothers and by their direct environment. 相似文献
2.
Simon W. Moolenaar 《Journal of Industrial Ecology》1999,3(1):41-53
The aim of sustainable heavy-metal management in agroecosystems is to ensure that the soil continues to fulfill its functions: in agricultural production, in environmental processes such as the cycling of elements, and as a habitat of numerous organisms. To understand and manage heavy-metal flows effectively, a consistent approach to modeling the flows is needed within the particular agro-system under study. General aspects of heavy-metal balance studies in agro-ecosystems were described in part I of this study. In this article (part II), several European studies of heavy-metal balances at varying spatial scales and in a variety of agro-ecosystems are reviewed. Sectoral studies at the national and international levels provide information for economic analyses and generic regulations; however, policies implemented at these levels often ignore farm characteristics and individual management options. Field-scale and farm-gate balances give farmers specific feedback on effective options for better heavy-metal management. Heavy-metal balances could be incorporated in an environmental management system of certified farms. In this way, farm certification may well serve as a basis from which to develop policy to address environmental issues in agriculture. 相似文献
3.
4.
Wojciech Roczniak Barbara Brodziak-Dopierała Elżbieta Cipora Agata Jakóbik-Kolon Joanna Kluczka Magdalena Babuśka-Roczniak 《Biological trace element research》2017,178(2):201-209
Osteoarthritis causes the degradation of the articular cartilage and periarticular bones. Trace elements influence the growth, development and condition of the bone tissue. Changes to the mineral composition of the bone tissue can cause degenerative changes and fractures. The aim of the research was to determine the content of cadmium (Cd), nickel (Ni), copper (Cu) and zinc (Zn) in the tibia, the femur and the meniscus in men and women who underwent a knee replacement surgery. Samples were collected from 50 patients, including 36 women and 14 men. The determination of trace elements content were performed by ICP-AES method, using Varian 710-ES. Average concentration in the tissues of the knee joint teeth amounted for cadmium 0.015, nickel 0.60, copper 0.89 and zinc 80.81 mg/kg wet weight. There were statistically significant differences in the content of cadmium, copper and zinc in different parts of the knee joint. There were no statistically significant differences in the content of cadmium, nickel, copper and zinc in women and men in the examined parts of the knee joint. Among the elements tested, copper and nickel showed a high content in the connective tissue (the meniscus) compared to the bone tissue (the tibia and the femur). 相似文献
5.
Rahman A Azad MA Hossain I Qusar MM Bari W Begum F Huq SM Hasnat A 《Biological trace element research》2009,127(2):102-108
The purpose of the study was to determine the concentration of trace elements present in scalp hair sample of schizophrenic
patients and to find out the relationship between trace elements level and nutritional status or socioeconomic factors. The
study was conducted among 30 schizophrenic male patients and 30 healthy male volunteers. Patients were recruited from Bangabandhu
Sheikh Mujib Medical University by random sampling. Hair trace element concentrations were determined by flame atomic absorption
spectroscopy and analyzed by independent t test, Pearson’s correlation analysis, regression analysis, and analysis of variance (ANOVA). Mn, Zn, Ca, Cu, and Cd concentrations
of schizophrenic patients were 3.8 ± 2.31 μg/gm, 171.6 ± 59.04 μg/gm, 396.23 ± 157.83 μg/gm, 15.40 ± 5.68 μg/gm, and 1.14 ± 0.89 μg/gm
of hair sample, while those of control subjects were 4.4 ± 2.32 μg/gm, 199.16 ± 27.85 μg/gm, 620.9 ± 181.55 μg/gm, 12.23 ± 4.56 μg/gm,
and 0.47 ± 0.32 μg/gm of hair sample, respectively. The hair concentration of Zn and Ca decreased significantly (p = 0.024; p = 0.000, respectively) and the concentration of Cu and Cd increased significantly (p = 0.021; p = 0.000, respectively) in schizophrenic patients while the concentration of Mn (p = 0.321) remain unchanged. Socioeconomic data reveals that most of the patients were poor, middle-aged and divorced. Mean
body mass indices (BMIs) of the control group (22.26 ± 1.91 kg/m2) and the patient group (20.42 ± 3.16 kg/m2) were within the normal range (18.5−25.0 kg/m2). Pearson’s correlation analysis suggested that only Ca concentration of patients had a significant positive correlation
with the BMI (r = 0.597; p = 0.000) which was further justified from the regression analysis (R
2 = 44%; t = 3.59; p = 0.002) and one-way ANOVA test (F = 3.62; p = 0.015). A significant decrease in the hair concentration of Zn and Ca as well as a significant increase in the hair concentration
of Cu and Cd in schizophrenic patients than that of its control group was observed which may provide prognostic tool for the
diagnosis and treatment of this disease. However, further work with larger population is suggested to examine the exact correlation
between trace element level and the degree of disorder. 相似文献
6.
Hong-qun Zhang Ning Li Zheng Zhang Shan Gao Hong-yin Yin Dong-mei Guo Xibao Gao 《Biological trace element research》2009,131(1):25-32
Sera of 890 healthy Jinan residents were chosen randomly, and the concentrations of serum Zn and Cu were detected by atomic
absorption spectrometry. The mean serum Zn and Cu concentrations and Zn/Cu were 1.32 ± 0.49 mg/l, 0.99 ± 0.26 mg/l, and 1.41 ± 0.56,
respectively. Significantly higher levels of serum Zn and Zn/Cu but lower serum Cu were found in the men. Descending tendency
of serum Zn and Zn/Cu was observed with social-economic status and age but not significant. Alcohol consumption produced higher
level of serum Zn and Zn/Cu but lower Cu concentration. Smoking caused significant lower level in serum Cu concentration but
no significance in serum Zn and Zn/Cu. Serum Zn and Zn/Cu were normal only when hours of sleep a night were kept within 7–9 h.
Higher level of serum Zn and Cu concentrations and Zn/Cu were observed in individuals with regular physical exercise, but
still no significant difference existed. No clear relationship between educational levels with serum Zn and Cu concentrations
and Zn/Cu was observed. 相似文献
7.
Nzengue Y Steiman R Rachidi W Favier A Guiraud P 《Biological trace element research》2012,146(3):410-419
In this report, we have investigated the role of copper (Cu) and zinc (Zn) in oxidative stress induced by cadmium (Cd) in
C6 cells. Cells were exposed to 20 μM Cd, 500 μM Cu, and 450 μM Zn for 24 h. Then, toxic effects, cellular metals levels,
oxidative stress parameters, cell death, as well as DNA damage were evaluated. Cd induced an increase in cellular Cd, Cu,
and Zn levels. This results not only in the inhibition of GSH-Px, GRase, CAT, and SOD activities but also in ROS overproduction,
oxidative damage, and apoptotic cell death not related to Cu and Zn mechanisms. The thiol groups and GSH levels decreased,
whereas the lipid peroxidation and DNA damage increased. The toxicity of Zn results from the imbalance between the inhibition
of antioxidant activities and the induction of MT synthesis. The increase in Cu and Zn levels could be explained by the disruption
of specific transporter activities, Cd interference with signaling pathways, and metal displacement. Our results suggest that
the alteration of Cu and Zn homeostasis is involved in the oxidative stress induced by Cd. 相似文献
8.
Saadia Ahmed Tayel Mohamed Ahmed El-Nabarawi Mina Ibrahim Tadros Wessam Hamdy Abd-Elsalam 《AAPS PharmSciTech》2013,14(2):782-793
Frequent instillation of terbinafine hydrochloride (T HCl) eye drops (0.25%, w/v) is necessary to maintain effective aqueous humor concentrations for treatment of fungal keratitis. The current approach aimed at developing potential positively charged controlled-release polymeric nanoparticles (NPs) of T HCl. The estimation of the drug pharmacokinetics in the aqueous humor following ocular instillation of the best-achieved NPs in rabbits was another goal. Eighteen drug-loaded (0.50%, w/v) formulae were fabricated by the nanopreciptation method using Eudragit® RS100 and chitosan (0.25%, 0.5%, and 1%, w/v). Soybean lecithin (1%, w/v) and Pluronic® F68 (0.5%, 1%, and 1.5%, w/v) were incorporated in the alcoholic and aqueous phases, respectively. The NPs were evaluated for particle size, zeta potential, entrapment efficiency percentage (EE%), morphological examination, drug release in simulated tear fluid (pH 7.4), Fourier-transform IR (FT-IR), X-ray diffraction (XRD), physical stability (2 months, 4°C and 25°C), and drug pharmacokinetics in the rabbit aqueous humor relative to an oily drug solution. Spherical, discrete NPs were successfully developed with mean particle size and zeta potential ranging from 73.29 to 320.15 nm and +20.51 to +40.32 mV, respectively. Higher EE% were achieved with Eudragit® RS100-based NPs. The duration of drug release was extended to more than 8 h. FT-IR and XRD revealed compatibility between inactive formulation ingredients and T HCl and permanence of the latter’s crystallinity, respectively. The NPs were physically stable, for at least 2 months, when refrigerated. F5-NP suspension significantly (P < 0.05) increased drug mean residence time and improved its ocular bioavailability; 1.657-fold.Key words: aqueous humor, chitosan, Eudragit® RS100, nanoparticles, terbinafine hydrochloride 相似文献
9.
Gholamabbas Sayyad Majid Afyuni Sayed-Farhad Mousavi Karim C. Abbaspour Mohammad A. Hajabbasi Brian K. Richards 《Soil & Sediment Contamination》2009,18(2):216-228
Accumulation of heavy metals (HMs) in cultivated soils is a continuing environmental problem in many parts of the world. An increase in HM concentration can enhance uptake of toxic metals by crops and enter the human food chain. In this study, the uptake behavior of wheat and safflower was evaluated in a calcareous soil by using 12 undisturbed columns in which half were artificially contaminated. Heavy metals in the form of CdCl2 (15 mg Cd kg? 1), CuSO4 (585 mg Cu kg? 1), Pb(NO3)2 (117 mg Pb kg? 1), and ZnCl2 (1094 mg Zn kg? 1) were sprayed on the soil surface and completely mixed in the top 10 cm. The background total concentrations of Cd, Cu, Pb and Zn were 1.6, 29.5, 17.5 and 61.2 mg kg? 1, respectively. After metal application, half of the columns (3 contaminated and 3 uncontaminated) were sown with wheat (Triticum aestivum) and the other half with safflower (Carthamus tinctorious) and grown for 74 days until maturity. After harvesting, soil columns were cut into 10-cm sections and analyzed for HNO3- and DTPA-extractable metal concentrations. Metal concentrations were also measured in different plant tissues. The results showed that artificial contamination of topsoil decreased the transpiration rate of wheat by 12% and that of safflower by 6%. In contaminated columns, Cd, Cu, Pb, and Zn accumulation in wheat shoot was greater by 8.0-, 1.9-, 3.0-, and 2.1-fold than the control, respectively. Accordingly, these numbers were 46.0-, 1.3-, 1.7-, and 1.6-fold in safflower shoot. Soil contamination with HMs resulted in a 55% decrease in shoot dry matter yield of wheat while it had no significant effect on shoot dry matter of safflower. The normalized water consumption for safflower was therefore not affected by metal contamination (≈ 13 mm H2O g? 1 of dry weight for all safflower and uncontaminated wheat treatments), while contaminated wheat was much less water efficient at about 27 mm H2O g? 1 dry weight. It was concluded that although artificial contamination had a negative effect on wheat growth, it did not affect safflower's normal growth and water efficiency. 相似文献
10.
Effects of Glucose Concentrations on Cadmium, Copper, Mercury, and Zinc Toxicity to a Klebsiella sp
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Lena Brynhildsen Bo V. Lundgren Bert Allard Thomas Rosswall 《Applied microbiology》1988,54(7):1689-1693
The influence of glucose concentration on Cd, Cu, Hg, and Zn toxicity to a Klebsiella sp. was studied by following the degradation of 14C-labeled glucose at pH 6.0. Uptake of 14C into the cells was also determined. The carbon concentrations ranged from 0.01 to 40 mg liter−1, which are equivalent to soluble C concentrations in natural environments. The toxicity of Cu, Cd, and Zn to a Klebsiella sp. was affected considerably by the C concentration. Copper at 10−5 M was toxic when the carbon concentration was 10 or 40 mg liter−1, while at 0.01 to 1.0 mg liter−1 no toxicity was observed. Cadmium and zinc were toxic at 10−2 M in media containing 0.01 to 1.0 mg of C liter−1. At C concentrations greater than 1.0 mg liter−1, the inhibition of glucose degradation and carbon assimilation was observed at 10−3 M Cd and Zn. The toxicity of mercury seemed to be independent of the C concentration. Results of this study showed that the nutritional state of an organism may have a profound effect on its sensitivity to metals. Metals taken up by an energy-driven transport system may be less toxic under conditions of C starvation. The C concentration should be taken into account when evaluating results from toxicity studies, especially as most microorganisms in nature live under energy-limited conditions. 相似文献
11.
Ana Mijovilovich Barbara Leitenmaier Wolfram Meyer-Klaucke Peter M.H. Kroneck Birgit G?tz Hendrik Küpper 《Plant physiology》2009,151(2):715-731
The cadmium/zinc hyperaccumulator Thlaspi caerulescens is sensitive toward copper (Cu) toxicity, which is a problem for phytoremediation of soils with mixed contamination. Cu levels in T. caerulescens grown with 10 μm Cu2+ remained in the nonaccumulator range (<50 ppm), and most individuals were as sensitive toward Cu as the related nonaccumulator Thlaspi fendleri. Obviously, hyperaccumulation and metal resistance are highly metal specific. Cu-induced inhibition of photosynthesis followed the “sun reaction” type of damage, with inhibition of the photosystem II reaction center charge separation and the water-splitting complex. A few individuals of T. caerulescens were more Cu resistant. Compared with Cu-sensitive individuals, they recovered faster from inhibition, at least partially by enhanced repair of chlorophyll-protein complexes but not by exclusion, since the content of Cu in their shoots was increased by about 25%. Extended x-ray absorption fine structure (EXAFS) measurements on frozen-hydrated leaf samples revealed that a large proportion of Cu in T. caerulescens is bound by sulfur ligands. This is in contrast to the known binding environment of cadmium and zinc in the same species, which is dominated by oxygen ligands. Clearly, hyperaccumulators detoxify hyperaccumulated metals differently compared with nonaccumulated metals. Furthermore, strong features in the Cu-EXAFS spectra ascribed to metal-metal contributions were found, in particular in the Cu-resistant specimens. Some of these features may be due to Cu binding to metallothioneins, but a larger proportion seems to result from biomineralization, most likely Cu(II) oxalate and Cu(II) oxides. Additional contributions in the EXAFS spectra indicate complexation of Cu(II) by the nonproteogenic amino acid nicotianamine, which has a very high affinity for Cu(II) as further characterized here.Many heavy metals are well known to be essential microelements for plants, but elevated concentrations of these metals cause toxicity (for review, see Prasad and Hagemeyer, 1999; Küpper and Kroneck, 2005), as explained in more detail in our companion article (Küpper et al., 2009) on copper (Cu) complexation and toxicity in Crassula helmsii. Plants developed a number of strategies to resist this toxicity, including active efflux, sequestration, and binding of heavy metals inside the cells by strong ligands. Among the zinc (Zn) and cadmium (Cd) hyperaccumulators (Brooks, 1998; Lombi et al., 2000), the best known species is Thlaspi caerulescens, which has been proposed as a hyperaccumulator model species by several authors (Assunção et al., 2003; Peer et al., 2003, 2006). An enhanced uptake of metals into the root symplasm was found in T. caerulescens compared with the related nonaccumulator Thlaspi arvense (Lasat et al., 1996, 1998), and a reduced sequestration into the root vacuoles was associated with the higher root-to-shoot translocation efficiency of T. caerulescens (Shen et al., 1997; Lasat et al., 1998). This is likely related to elevated expression of xylem-loading transporters in the roots (Papoyan and Kochian, 2004; Weber et al., 2004). One of these, the Cd/Zn-pumping P1b-type ATPase TcHMA4, was recently purified as a protein, which revealed posttranslational processing, and its biochemical characterization showed Cd and Zn transport affinity in the submicromolar range (Parameswaran et al., 2007). Studies of cellular metal compartmentation have shown that in most hyperaccumulators, the metal is sequestered preferentially into compartments where it does no harm to the metabolism. These are, in most cases studied so far, the epidermal vacuoles (Küpper et al., 1999, 2001; Frey et al., 2000; Bidwell et al., 2004; Broadhurst et al., 2004), where concentrations of several hundred mmol L−1 can be reached in the large metal storage cells (Küpper et al., 1999, 2001). The latter showed that hyperaccumulation must be mediated by active pumping of the heavy metals into their storage sites, which was shown to be achieved by an extremely increased expression of metal transport proteins in leaves of hyperaccumulators compared with nonaccumulators (Pence et al., 2000; Assunção et al., 2001; Becher et al., 2004; Papoyan and Kochian, 2004; Küpper et al., 2007b). Strong sulfur (S) ligands like phytochelatins were shown not to be relevant for Cd detoxification in the Cd hyperaccumulator T. caerulescens. Phytochelatin levels are lower in this plant than in the related nonaccumulator T. arvense (Ebbs et al., 2002), inhibition of phytochelatin synthase in hyperaccumulators does not affect their Cd resistance (Schat et al., 2002), and direct measurements of the Cd ligands by EXAFS (Küpper et al., 2004). Thus, the main detoxification strategy in hyperaccumulators is clearly not binding to strong ligands but sequestration of the hyperaccumulated heavy metals. However, the nonproteogenic amino acid nicotianamine (NA) seems to play an important role in metal homeostasis of plants. According to several studies, it binds iron, Zn, and Cu, mainly for long-distance transport in the vascular bundle (Stephan and Scholz, 1993; Pich et al., 1994; Schmidke and Stephan, 1995; Stephan et al., 1996, Pich and Scholz, 1996; von Wiren et al., 1999; Liao et al., 2000), and NA synthase has been shown to be highly overexpressed in hyperaccumulators compared with nonaccumulator plants (Becher et al., 2004; Weber et al., 2004; van de Mortel et al., 2006, 2008).
Open in a separate windowUnder metal-induced stress, the heavy metal accumulation pattern changes. Under such conditions, heavy metal (Cd, nickel) accumulation was enhanced in a few cells of the mesophyll (Küpper et al., 2000a, 2001). The same cells contained elevated levels of magnesium, which was interpreted as a defense against substitution of Mg2+ in chlorophyll (Chl; Küpper et al., 1996, 1998, 2002) by heavy metals. Recently, it was found that this heterogeneity of Cd accumulation is a transient phenomenon in T. caerulescens under Cd-toxicity stress, correlating with a heterogeneity in photosynthesis and disappearing when the plants acclimate to the stress (Küpper et al., 2007a). It was postulated that this transient heterogeneity constitutes an emergency defense against Cd toxicity by sacrificing a few mesophyll cells as additional storage sites until the metal sequestration in the epidermis is sufficiently up-regulated. Furthermore, this acclimation response showed that at least part of the Cd resistance of T. caerulescens is inducible (Küpper et al., 2007a).While Cd resistance of T. caerulescens is strongly enhanced compared with related nonaccumulator plants, T. caerulescens is known to be sensitive to Cu to a similar extent as nonaccumulator plants, limiting its application for phytoremediating soils with mixed contamination (Walker and Bernal, 2004; Benzarti et al., 2008).In contrast to other metals, the speciation (redox state and coordination) of Cu in plant tissues is poorly understood, despite the detailed structural and functional knowledge about numerous Cu-dependent enzymes and Cu chaperones (for review, see Pilon et al., 2006). This is most likely due to the difficulty of measuring Cu speciation. The concentrations of Cu in plant tissue are too small for NMR and were too small for EXAFS for a long time. Methods relying on fractionation or homogenization of fresh tissues (e.g. for chromatography) cause breaking of intracellular membranes. This brings weakly bound metal that was localized in the vacuole into contact with the various strong ligands of the cytoplasm, causing artifactual changes of speciation. To our knowledge, so far only one EXAFS study on Cu speciation in plant tissues used environmental Cu concentrations: Polette et al. (2000) studied Cu speciation in the Cu-resistant Cu indicator plant Larrea tridentata. In their EXAFS measurements on samples frozen in liquid nitrogen, they found evidence for a Cu(II)-phytochelatin complex involved in transport and an unknown Cu complex involved in Cu storage. A second study using the same sample preparation method (that due to the formation of a gas layer around the sample slows freezing, resulting in ice formation with the risk of membrane damage) investigated the Cu-tolerant Cu-excluder plant Elsholtzia splendens (Shi et al., 2008). Unfortunately, these authors applied very high, physiologically not relevant Cu levels (300 μm) in their nutrient solution in order to force enough Cu into the tissues to get an acceptable signal-noise level in their EXAFS data within the limited synchrotron beam time. In two further Cu-EXAFS studies on plant tissues (Gardea-Torresdey et al., 2001, on L. tridentata; Sahi et al., 2007, on Sesbania drummondii), strong artifacts were most likely introduced by drying of tissues. Drying disrupts membranes as discussed above and can remove aquo ligands from metal ions (Schünemann et al., 1999). Additionally, extremely high Cu concentrations in the nutrient solution were applied to the plants (1,000 and 10,000 μm by Gardea-Torresdey et al., 2001; 400–5,000 μm by Sahi et al., 2007). Thus, the biological relevance of these studies has to be questioned.In this study, we addressed two related questions, both in comparison with the Cu accumulator C. helmsii described by Küpper et al. (2009). How do environmentally relevant (10 μm) toxic levels of Cu affect T. caerulescens? And how does the plant try to defend itself by binding the Cu ions? This was done by investigating mechanisms of Cu-induced inhibition of photosynthesis and analyzing the complexation of Cu in leaves. The latter was done in order to find out whether T. caerulescens utilizes different mechanisms for detoxification of the nonaccumulated Cu in comparison with the hyperaccumulated Cd. The speciation of Cu was analyzed by EXAFS, which is an element-specific method and therefore particularly suited for analyzing the in vivo ligand environment of metals in plants. Furthermore, in contrast to most other methods, it is applicable to intact frozen-hydrated plant tissues, which were first used by Salt et al. (1995). Moreover, EXAFS beamlines can now reach much lower metal concentrations than heteronuclear NMR (Ascone et al., 2003). So far, metal NMR was applied only in the case of Cd in T. caerulescens (Ueno et al., 2005), but although the concentration of this hyperaccumulated metal in the tissue was about 100 times higher than that of Cu, the NMR signal obtained was so weak that only the most abundant ligand type (organic acids, confirming previous EXAFS work [Küpper et al. 2004]) could be detected; everything else was drowned in noise. Thus, EXAFS is the method of choice for identifying ligands of both Cu(I) and Cu(II) in intact tissues in the absence of artifacts introduced by sample preparation (see above). EXAFS model complexes were prepared as references, and among these, Cu(II)-NA was characterized in more detail by UV/VIS and electron paramagnetic resonance (EPR) spectroscopy in view of its importance for Cu(II) binding in T. caerulescens. Inhibition of photosynthesis was investigated, as in our C. helmsii study, by the two-dimensional (imaging) microscopic in vivo measurement of the transients of Chl variable fluorescence with a recently described instrument, the fluorescence kinetic microscope (FKM; Küpper et al., 2007a). This was complemented with data on Cu accumulation, changes in pigment composition, and plant growth. 相似文献
Table I.
Explanation of technical termsTechnical Term | Explanation/Definition |
---|---|
Antenna connectivity | The likelihood of energy transfer between antennae of different photosystems (PSII and/or PSI) |
DW | Debye-Waller factor of the EXAFS refinements, accounts for both structural and thermal disorder of the metal ion coordination shells (Binstead et al., 1992) |
EF | Fermi energy of the EXAFS refinements, defines the threshold for the EXAFS spectra (Rehr and Albers, 2000) |
EXAFS | Extended x-ray absorption fine structure |
FI | Fit index of the EXAFS refinements = sum of the square of the residuals (this is what is minimized in the refinement) |
F0 | Minimal fluorescence yield of a dark-adapted sample, fluorescence in nonactinic measuring light |
Fm | Maximum fluorescence yield of a dark-adapted sample after supersaturating irradiation pulse |
Fm′ | Maximum fluorescence yield of a light-adapted sample after supersaturating irradiation pulse |
Fp | Fluorescence yield at the P level of the induction curve after the onset of actinic light exposure |
Fv = Fm − F0 | Variable fluorescence |
Fv/Fm = (Fm − F0)/Fm | Maximal dark-adapted quantum yield of PSII photochemistry |
ΦPSII = Φe = (Fm′ − Ft′)/Fm′ | The light-acclimated efficiency of PSII (Genty et al., 1989). In this article, the use of this parameter is extended to the relaxation period after the end of actinic light to analyze the return of the system to its dark-acclimated state as measured by Fv/Fm. |
k | Wave number of the photoelectron, proportional to the square of the energy difference from the threshold energy (Efermi) |
k-range | Energy range above the x-ray absorption edge of the metal where EXAFS was analyzed. |
Light saturation | Measured by the increased amplitude of Fp relative to Fm after subtraction of F0. (Fp − F0)/(Fm − F0) is mostly dependent on the ratio of functional antenna molecules to functional reaction centers and electron transport chains. Under constant actinic irradiance for measuring Fp, a large antenna capturing photons and delivering them to its reaction center will cause more of the “electron traffic jam” that leads to Fp than a small antenna. |
Multiple scattering | Contributions in EXAFS that originate not from direct interaction between the central ion and another atom, but from interactions between the different atoms of a ligand molecule. This can only be observed in very rigid (parts of) ligand molecules, e.g. the imidazole ring of His. Further, the contribution is most significant for forward scattering at angles close to 180°, which is the case for the atoms in an imidazole ring. |
NPQ = (Fm − Fm′)/Fm | Nonphotochemical quenching, in this article used as an acronym for the name of this phenomenon. In this article, we measure nonphotochemical quenching as qCN = “complete nonphotochemical quenching of Chl fluorescence”, i.e. with normalization to Fm. |
Z | Atomic number |
12.
The contamination of soils with heavy metals is a global disaster that is related to human activities. Phytostabilization basically refers to the use of metal-tolerant plants and inexpensive mineral or organic soil amendments to reduce the concentrations or toxic effects of contaminants in the environment. Here, we tested the effects of four cost-effective amendments (CaCO3, phosphate rock, activated carbon, and exhausted olive cake ash) on Cd, Zn, and Cu leaching and uptake by ryegrass (Lolium perenne L.). The results showed that all amendments reduced Cd, Zn, and Cu leaching, mainly due to the alkalinity increase. Among all amendments tested, CaCO3 was the most effective treatment in decreasing both the heavy-metal leaching and concentrations in ryegrass shoots. Results obtained suggest the efficacy of several amendments, but further work is needed to gain insight into their possible synergetic effects. 相似文献
13.
Plasma Copper, Zinc, and Selenium Levels and Correlates with Metabolic Syndrome Components of Lebanese Adults 总被引:1,自引:0,他引:1
Obeid O Elfakhani M Hlais S Iskandar M Batal M Mouneimne Y Adra N Hwalla N 《Biological trace element research》2008,123(1-3):58-65
Zinc, copper, and selenium statuses were reported to be linked to the development of chronic diseases, especially coronary heart disease (CHD). Metabolic syndrome, a known CHD risk factor, was found to be highly prevalent in Lebanon. Nevertheless, no data are available on the statuses of plasma zinc, copper, and selenium, especially in terms of their relation to the components of the metabolic syndrome. A sample of 398 men and women aged 18-65 years was drawn from 23 health centers across Lebanon; anthropometric measurements and biochemical analyses of fasting plasma samples were performed. Subjects were found to have normal plasma statuses of copper and selenium but were at elevated risk of zinc deficiency. Plasma selenium levels correlated positively with all the components of the metabolic syndromes, while that of copper correlated only with total, high-density lipoprotein and low-density lipoprotein cholesterol. Plasma zinc did not correlate with any of the metabolic syndrome components. 相似文献
14.
Manal E. Sharif Isahg Adam Mohamed A. Ahmed Duria A. Rayis Hamdan Z. Hamdan 《Biological trace element research》2017,179(1):23-31
The paper’s objective was to estimate weekly Hg intake from fish meals based on intervention research. Total Hg (THg) concentrations in blood and hair samples collected from men (n = 67) from an intervention study as well as muscular tissues of fresh and after heat-treating fish were determined using the thermal decomposition amalgamation atomic absorption spectrometry method (TDA-AAS) using direct mercury analyzer (DMA-80). The mean of the estimated weekly intake (EWI) was estimated at 0.62 μg/kg bw/week in the range 0.36–0.96 μg/kg body weight (bw) /week through the consumption of 4 edible marine fish species every day (for 10 days) by the participants from the intervention research in Lodz, Poland. The Hg intake in the volunteers in our intervention study accounted for 38.6% of the provisional tolerable weekly intake (PTWI) (1.6 μg/kg bw, weekly) value. The average Hg concentration in the analyzed fish ranged from 0.018 ± 0.006 mg/kg wet weight (Gadus chalcogrammus) to 0.105 ± 0.015 mg/kg wet weight (Macruronus magellanicus). The results for the average consumers were within PTWI of methylmercury (MeHg). Moreover, the average concentration of Hg in the selected fish after heat treatment did not exceed the maximum permitted concentrations for MeHg (MPCs = 0.5 mg/kg wet weight) in food set by the European Commission Regulation (EC/1881/2006). Hence, the risk of adverse effects of MeHg for the participants is substantially low. 相似文献
15.
The serum concentrations of copper, zinc, iron, and cobalt and copper/zinc ratio were investigated in horses infected with
equine herpesvirus-1 (EHV-1). Nine horses were naturally infected with the virus and nine healthy horses served as controls.
The concentrations of copper, zinc, iron, and cobalt were determined spectrophotometrically in the blood serum of all horses.
The results were (expressed in micrograms per deciliters) copper 2.80 ± 0.34 vs 1.12 ± 0.44, zinc 3.05 ± 0.18 vs 0.83 ± 0.06,
iron 2.76 ± 0.17 vs 3.71 ± 0.69, cobalt 0.19 ± 0.37 vs 0.22 ± 0.45, and copper/zinc ratio 0.72 ± 0.38 vs 1.41 ± 0.36 for control
vs infected group, respectively. In conclusion, copper and zinc concentrations of the infected group were lower than the control
group (p < 0.001), whereas iron concentration and the copper/zinc ratio of the infected group were higher than the control group (p < 0.05 and p < 0.001). The cobalt concentration was not found to be statistically different between two groups. It might be emphasized
that copper/zinc ratio was significantly affected by the EHV-1 infection, so it could be taken into consideration during the
course of infection.
An erratum to this article can be found at 相似文献
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17.
We have determined the plasma concentrations of copper, zinc, copper/zinc ratio, and carbonic anhydrase activity in horses
infected with Babesia equi. The study was conducted in 14 horses with the disease and 10 healthy animals that served as controls. The infection was
confirmed by the clinical manifestations of the disease and by Giemsa staining of thin blood smears showing the parasites
inside red blood cells. The horses with piroplasmosis had lower plasma levels of zinc, elevated copper, and increased activity
of carbonic anhydrase. Consequently, the copper/zinc ratio was also higher than in the healthy controls. 相似文献
18.
Ayşegül Bayır Hasan Kara Aysel Kıyıcı Bahadır Öztürk Fikret Akyürek 《Biological trace element research》2013,154(3):352-356
The aim of this study was to assess the levels of selenium (Se), zinc (Zn), copper (Cu), and troponin I (TnI) in patients with acute coronary syndrome (ACS) on admission to our emergency department in comparison to healthy control subjects. Patients with diagnosed ACS (n?=?100) were included in the study group. Control subjects (n?=?100) were selected from healthy volunteers in the same age range. Venous blood samples were obtained to evaluate the levels of Se, Zn, Cu, and TnI (on admission for the ACS group). Serum Se, Zn, and Cu levels were significantly less in the ACS group compared to the control group (p <0.001, p <0.01, and p <0.001, respectively). The serum TnI level was significantly greater in the ACS group compared to the control group (p <0.05). The serum Se level in the ACS group correlated significantly with the TnI level (r?=??0.211, p?=?0.035). These results indicate that Se, Zn, and Cu deficiencies may be risk factors for ACS, and a decreased serum Se level in patients with ACS might reflect the degree of myocardial necrosis. 相似文献
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20.
The Action of Divalent Zinc, Cadmium, Mercury, Copper and Lead on the Trans-Root Potential and H+, Efflux of Excised Roots 总被引:4,自引:0,他引:4
Kennedy, C. D. and Gonsalves, F. A. N. 1987. The action of divalentzinc, cadmium, mercury, copper and lead on the trans-root potentialand H+ efflux of excised roots.J. exp. Bot. 38: 800817. The action of Zn2+, Cd2+, Hg2+, Cu2+ and Pb2+ ions on the trans-rootpotential and H+ efflux of young excised maize roots has beenstudied. Micro-electrode implantations into root epidermal cellsconfirmed the root outer membranes as the major contributorin the trans-root potential changes. The effects of these ionson H+ efflux were studied over a period of time in a continuousflow cell apparatus, adequate controls allowing for transientinterference due to divalent cations at the pH probe. The addition of Zn2+, 5 to 100 µmol dm3, to thesolution bathing the roots reduces H+ efflux and depolarizesthe trans-root potential. However, in the presence of Mg2+,0?1 or 1?0 mmol dm3, not only is this depolarizationinhibited, but hyperpolarization is observed instead. Cd2+ affectstrans-root potential and H+ efflux at a much slower rate thanZn2+, suggesting a lower membrane permeability. Without Mg2+,Cd2+ hyperpolarizes the trans-root potential, but this is bettersustained in its presence. Hyperpolarization did not occur withHg2+, Cu2+ or Pb2+ whether or not Mg2+ was present Hg2+ andto a lesser extent Cu2+ are potent depolarizers of the trans-rootpotential and strongly inhibit H+ efflux. The maximum rates of depolarization observed in the absenceof Mg2+ increase in the order Cd PCMBS <<.lt; Zn Cu< Hg. This is similar to the relative maximum rates of H+inhibition, Pb Cd <<.lt; Zn < Cu < Hg, suggestingconsiderable differences in mode of action and/or membrane permeability.The lower membrane permeability of the sulphydryl reagent PCMBSapparently prevents ready access to the site(s) of action availableto Hg2+. The reductions in trans-root potential and H+ gradients inducedby this range of cations would be detrimental to the acquisitionof nutrients using these gradients as an energy source. In contrast,Zn2+, , in the presence of adequate Mg2+, could be beneficialto nutrient uptake by maintaining a higher membrane potentialthan would occur in its absence. Possible modes of action for the observed effects are discussed. Key words: Trans-root potentials, H+ efflux, heavy metal ions 相似文献