Effect Of Ferrous Iron Research Articles

Effects of ferrous iron (Fe) on the germination and root elongation of paddy rice and weeds

Laboratory experiments were conducted to analyze the iron (Fe) tolerance of paddy weeds and rice varieties (Oryza sativa) for germination and root elongation. Under a waterlogged soil condition, the Fe(II) content in a soil solution increased with an increase in the ratio of rice straw to the soil. In the presence of 0.9% (w/w) straw to soil, which corresponds approximately to 8 t of straw applied to an area of 1 ha × 10 cm depth in the field, ∼80 mg L−1 of Fe(II) was produced in the soil solution. Based on this result, the seeds of rice and the weeds were incubated in a solution with <100 mg L−1 of Fe(II). The presence of 100 mg L−1 of Fe(II) suppressed the germination of Echinochloa crus‐galli var. crus‐galli, Cyperus serotinus, Cyperus difformis, and Monochoria korsakowii. However, it had no effect on the germination of Echinochloa oryzicola, Schoenoplectus juncoides (= Scirpus juncoides var. ohwianus), and Monochoria vaginalis. This level of Fe tolerance was the same as that of rice. These findings suggest that E. oryzicola, S. juncoides, and M. vaginalis can grow under more severe conditions than E. crus‐galli, C. serotinus, C. difformis, and M. korsakowii. In relation to seminal root elongation, the order of tolerance of Fe toxicity was O. sativa cv. Dunghan Shali > O. sativa cv. Hoshinoyume > E. oryzicola > M. vaginalis > S. juncoides. Thus, the results show that the tolerance of rice is greater than that of E. oryzicola, which had a comparatively strong tolerance among the weeds examined, and also that there are differences in tolerance among the rice varieties. These findings suggest that the difference in Fe tolerance is involved in weed control systems when organic materials are applied. If this difference is an important factor in the weed control system, Fe‐tolerant rice varieties, like cv. D. Shali, could facilitate weed control systems due to their higher Fe tolerance ability.

Effects of Intracerebroventricular Injection of Iron Dextran on the Iron Concentration and Divalent Metal Transporter 1 Expression in the Caudate Putamen and Substantia Nigra of Rats

The cellular localization of DMT1 and its functional characterization suggest that DMT1 may play an important role in the physiological brain iron transport. But the regulation of DMT1 expression by iron in the brain is still not clearly understood. In this study, both the contents of ferric and ferrous iron as well as DMT1 expression were evaluated in CPu and SN after ICV of 500 microg iron dextran/rat/day for 3 or 7 days. It was found that the iron levels in CPu and SN were not altered obviously until ICV for 7 days. Immunohistochemistry results indicated that the expression of DMT1 (-IRE) in CPu and SN was not altered significantly after 3 days of ICV. Whereas the expression of DMT1 (-IRE) decreased significantly after 7 days of ICV when ferrous iron was increased significantly. Contrary to that of DMT1 (-IRE) in the same regions, there were no significant alterations in DMT1 (+IRE) expression in CPu and SN in spite of the existence of the altered iron levels, compared with that of control groups. The results demonstrate that DMT1 (-IRE) expression was correlated probably with brain iron levels; especially, its regulation was correlated with ferrous iron (not ferric iron) in CPu and SN in adult rats, compared with those of saline-injected control rats. The effect of ferrous iron on the expression of DMT1 (-IRE) in the brain also suggests that it might play a major physiological role in brain iron uptake and transport, but further studies are needed to clarify these issues.

Effect of Ferrous Iron on Arsenate Sorption to Amorphous Ferric Hydroxide

Amorphous ferric hydroxide (AFH) sorbents are commonly used for removal of arsenate from water. When disposed in microbially active, reducing environments, such as landfills, Fe(II) will be generated by reductive dissolution of the AFH surface and arsenate will be desorbed. However, the observed ratio of arsenate (and, in fact, total arsenic) to total iron in the leachate is not consistent with the original ratio of arsenate to iron on the AFH. Work to determine if ferrous iron re-adsorption to the AFH can partially explain this inconsistency is described. As pH increases above 7, Fe(II) increasingly sorbs onto the AFH surface. This sorption is largely independent of ionic strength and somewhat irreversible at high pH. In contrast, arsenate partitioning to AFH decreases with increasing pH. However, over the pH range from 5 to 9, the presence of Fe(II) sorbed to the AFH surface increases the capacity for arsenate sorption. In addition, when no Fe(II) is present, arsenate binding is largely to surface sites inaccessible to Fe(II) binding. The results are also consistent with Fe(II) sorption to AFH sites, otherwise unfavorable to arsenate binding and transformation of those sites into arsenate-amenable binding sites.

Effect of Ferric Iron on Siderophore Production and Pyrene Degradation by Pseudomonas fluorescens 29L

The effect of ferric iron [Fe(III)] on pyrene degradation and siderophore production was studied in Pseudomonas fluorescens 29L. In the presence of 0.5 microM of Fe(III) and 50 mg of pyrene per liter of medium as a carbon source, 2.2 mg of pyrene was degraded per liter of medium per day and 25.3 microM of 2,3-DHBA (2,3-dihydroxybenzoic acid) equivalent of siderophores was produced per day. However, the pyrene degradation rate was 1.3 times higher and no siderophores were produced with the addition of 1 microM of Fe(III). Similar trends were seen with 50 mg of succinate per liter of medium as a carbon source, although the growth of strain 29L and the succinate degradation rate were higher. In the absence of siderophore production, pyrene and succinate continued to be biodegraded. This indicates that Fe(III) and not siderophore production affects the hydrocarbon degradation rate. Only 18% of strain 29L mutants capable of growth on pyrene produced siderophores, while among the mutants capable of growth on succinate, only 10% produced siderophores. This indicates that siderophores are not required for pyrene biodegradation. Fe(III) enhances pyrene degradation in Pseudomonas fluorescens 29L but it may be utilized by mechanisms other than siderophores.

Molecular interactions of artemisinin with DNA and specific target proteins in cancer cells

The anti-malarial artemisinin from Artemisia annua L. also inhibits tumor cells in vitro and in vivo. Artemisinin induces apoptosis, but cellular upstream mechanisms are not understood. The susceptibility of tumor cells to artemisinin and its derivative, artesunate, was enhanced by ferrous iron. The transferrin receptor (TfR) transports iron and is overexpressed in tumors. The effect of ferrous iron on artesunate was reversed by monoclonal antibody RVS10, which competes with transferrin for TfR-binding [1]. The ATP-binding cassette transporter, ABCB6, is also involved in iron homeostasis. In 36 tumor cell lines, TfR and ABCB6 expression significantly correlated with the efficacy of artesunate and ferrous iron to inhibit growth. Down-regulation of ABCB6 by antisense oligodeoxynucleotides inhibited cellular differentiation and proliferation in MEL erythroleukemia cells [2]. Artesunate also induced DNA breakage as shown by Comet assay. Single strand breaks were repaired by base excision repair, double strand breaks by homologous repair and non-homologous end-joining [3]. By three-dimensional docking studies, the translationally controlled tumor protein (TCTP) was shown to bind artesunate at cysteine 124. This was verified by gene cloning the gene, protein expression and purification and mass spectrometry.

The effects of ferric iron on voltage-gated potassium currents in molluscan neurons

In isolated neurons of Helix pomatia, a two-microelectrode voltage clamp technique was used to study the effect of Fe3+ on voltage-gated potassium currents: a low-threshold fast-inactivating current (I(A)) and a high threshold slow-inactivating current with calcium-dependent (I(C)) and calcium-independent (I(DR)) components. Extracellular application of FeCl3 rapidly, reversibly and dose-dependently reduced the amplitude of I(A), I(C) and I(DR) with IC50 values of 49, 45 and 70 microM, respectively. Complete inhibition of K+ currents was reached at 100-500 microM Fe3+. The threshold for the total slow-inactivating potassium current shifted in a positive direction by 10-30 mV in the presence of Fe3+ (50-300 microM). Our work is the first demonstration of the strong blocking effect of Fe3+ on potassium currents of neuronal membrane.

Kinetics of iron oxidation by Leptospirillum ferriphilum dominated culture at pH below one

The kinetics of ferrous iron oxidation by Leptospirillum ferriphilum (L. ferriphilum) dominated culture was studied in the concentration range of 0.1-20 g Fe(2+)/L and the effect of ferric iron (0-60 g Fe(3+)/L) on Fe(2+) oxidation was investigated at pH below one. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes followed by partial sequencing confirmed that the bacterial community was dominated by L. ferriphilum. In batch assays, Fe(2+) oxidation started without lag phase and the oxidation was completed within 1 to 60 h depending on the initial Fe(2+) concentration. The specific Fe(2+) oxidation rates increased up to around 4 g/L and started to decrease at above 4 g/L. This implies substrate inhibition of Fe(2+) oxidation at higher concentrations. Haldane equation fitted the experimental data reasonably well (R(2) = 0.90). The maximum specific oxidation rate (q(m)) was 2.4 mg/mg VS . h, and the values of the half saturation (K(s)) and self inhibition constants (K(i)) were 413 and 8,650 mg/L, respectively. Fe(2+) oxidation was competitively inhibited by Fe(3+) and the competitive inhibition constant (K(ii)) was 830 mg/L. The time required to reach threshold Fe(2+) concentration was around 1 day and 2.3 days with initial Fe(3+) concentration of 5 and 60 g/L, respectively. The threshold Fe(2+) concentration, below which no further Fe(2+) oxidation occurred, linearly increased with increasing initial Fe(2+) and Fe(3+) concentrations. Fe(2+) oxidation proceeds by L. ferriphilum dominated culture at pH below 1 even in the presence of 60 g Fe(3+)/L. This indicates potential of using and biologically regenerating concentrated Fe(3+) sulfate solutions required, for example, in indirect tank leaching of ore concentrates.

Elasticity of (Mg, Fe)(Si, Al)O3-perovskite at high pressure

The most abundant mineral on Earth has a perovskite crystal structure and a chemistry that is dominated by MgSiO3 with the next most abundant cations probably being aluminum and ferric iron. The dearth of experimental elasticity data for this chemically complex mineral limits our ability to calculate model seismic velocities for the lower mantle. We have calculated the single crystal elastic moduli (c(ij)) for (Mg, Fe3+)(Si, Al)O-3 perovskite using density functional theory in order to investigate the effect of chemical variations and spin state transitions of the Fe3+ ions. Considering the favored coupled substitution of Mg2+-Si4+ by Fe3+-Al3+, we find that the effect of ferric iron on seismic properties is comparable with the same amount of ferrous iron. Ferric iron lowers the elastic moduli relative to the Al charge-coupled substitution. Substitution of Fe3+ for Al3+, giving rise to an Fe/Mg ratio of 6%, causes 1.8% lower longitudinal velocity and 2.5% lower shear velocity at ambient pressure and 1.1% lower longitudinal velocity and 1.8% lower shear velocity at 142 GPa. The spin state of the iron for this composition has a relatively small effect (<0.5% variation) on both bulk modulus and shear modulus. (C) 2005 Elsevier B.V. All rights reserved.

Enhancement of cytotoxicity of artemisinins toward cancer cells by ferrous iron

Iron(II) heme-mediated activation of the peroxide bond of artemisinins is thought to generate the radical oxygen species responsible for their antimalarial activity. We analyzed the role of ferrous iron in the cytotoxicity of artemisinins toward tumor cells. Iron(II)–glycine sulfate (Ferrosanol) and transferrin increased the cytotoxicity of free artesunate, artesunate microencapsulated in maltosyl-β-cyclodextrin, and artemisinin toward CCRF-CEM leukemia and U373 astrocytoma cells 1.5- to 10.3-fold compared with that of artemisinins applied without iron. Growth inhibition by artesunate and ferrous iron correlated with induction of apoptosis. Cell cycle perturbations by artesunate and ferrous iron were not observed. Treatment of p53 wild-type TK6 and p53 mutated WTK1 lymphoblastic cells showed that mutational status of the tumor suppressor p53 did not influence sensitivity to artesunate. The effect of ferrous iron and transferrin was reversed by monoclonal antibody RVS10 against the transferrin receptor (TfR), which competes with transferrin for binding to TfR. CCRF-CEM and U373 cells expressed TfR in 95 and 48% of the cell population, respectively, whereas TfR expression in peripheral mononuclear blood cells of four healthy donors was confined to 0.4–1.3%. This indicates that artemisinins plus ferrous iron may affect tumor cells more than normal cells. The IC 50 values for a series of eight different artemisinin derivatives in 60 cell lines of the U.S. National Cancer Institute were correlated with the microarray mRNA expression of 12 genes involved in iron uptake and metabolism by Kendall's τ test to identify iron-responsive cellular factors enhancing the activity of artemisinins. This pointed to mitochondrial aconitase and ceruloplasmin (ferroxidase).

Statistical Analysis of the Links among Lunar Mare Soil Mineralogy, Chemistry, and Reflectance Spectra

A principal goal of the Lunar Soil Characterization Consortium (LSCC) is to evaluate tools that might be successfully used in remote compositional analysis of the lunar surface. Mathematical methods are extremely valuable to assess whether variations exist in a statistically significant manner, independent of their interpretation. The bounds of widely used correlation of visible to near-infrared spectral parameters with composition are first defined and evaluated. We then evaluate direct (or indirect) links between the combined spectral properties of lunar mare soils and their compositional properties (elemental abundance and mineralogy) through a statistical analysis of the variance across each measurement using principal component analysis (PCA). We first separately analyze LSCC elemental abundance, mineralogy, and spectroscopy data (0.35 to 2.5 μm) using PCA to capture the variance of each system with a relatively small number of independent variables. With this compact set of independent variables for each type of data, we derive functions to link composition and spectroscopy. For these mare soils, one of the best empirical predictive capability is that for FeO. This is not surprising since the effect of ferrous iron on optical properties is well documented. Although Al 2O 3 has no direct effect on optical properties, its strong anticorrelation with FeO also produces a relatively high predictive capability from spectra. Similarly, a high accuracy in predicting the abundance of pyroxene is observed and should be expected since iron-bearing pyroxene is one of the most optically active components of lunar soil. The accuracy for predicting either TiO 2 or ilmenite, on the other hand, is disappointing. High- and low-Ti soils are readily distinguished, but these statistics suggest that making subclass distinctions based on spectral predictions of TiO 2 would be risky.

Effects of ferrous iron and molecular oxygen on chromium(VI) redox kinetics in the presence of aquifer solids

The kinetics and stoichiometry of the reduction of hexavalent chromium (Cr(VI)) with ferrous iron (Fe(II)) were examined in systems with and without aquifer solids. Cr(VI) reduction was rapid in the absence of solids, but demonstrated slower and more complex kinetics in the presence of aquifer solids. The aquifer solids removed Fe(II) from solution and a portion of the reducing capacity of Fe(II) was transferred to the aquifer solids. The solid phases were then able to continue to remove Cr(VI). This suggests in situ treatment of Cr(VI) by Fe(II) injection would be feasible in the aquifer environment. In general, re-oxidation of reduced chromium by molecular oxygen was not observed in our systems over time periods of nearly 1 year, suggesting that the potential for chromium solubilization under these oxidizing conditions will be low. An empirical model was developed to describe the reduction kinetics of Cr(VI) in the presence of solids. The model assumes that the reaction is brought about by pseudo-species of iron that react instantaneously, rapidly and slowly with Cr(VI). A fourth pseudo-species is assumed to be non-reactive. Model coefficients were determined by non-linear regression. The model was able to describe observed concentrations of chromium well, but analysis of model errors indicated the potential existence of a distribution of species with different reaction rates rather than just three distinct species. Another model was developed to predict concentrations of different pseudo-species depending on the total amount of Fe(II) added and the amount of aquifer solids present. This model assumed that pseudo-species could result from intrinsic characteristics of the aquifer solids as well as being formed by addition of Fe(II), which could sorb to the aquifer solids.

An experimental study on iron removal with ferric sludge recycling

An iron removal process, which makes use of the catalytic effect of ferric iron, is proposed. For this purpose, the reaction kinetics derived from the data of the batch experiments was applied to the continuous flow system. Based upon this reaction kinetics, it has been theoretically demonstrated that the volumes of aeration tanks can be significantly reduced by keeping a high concentration of ferric iron in the reactor. However, in natural waters, Fe(II) is found commonly to be in the range of 0.01–10 mg/l. These ferrous iron concentrations are not high enough to maintain the high concentrations of ferric iron in the aeration tank. Therefore, similar to the activated sludge processes used in wastewater treatment, it is suggested that the required Fe(III) concentrations can be maintained by recycling Fe(OH)3 sludge back to the aeration tank. It is known that the oxygenation of ferrous iron is catalyzed by the reaction product, ferric hydroxide. Catalytic action of the ferric iron sludges on the oxidation of ferrous iron by aeration has been identified and the kinetics of this catalytic reaction has been formulated by the authors. The oxidation of Fe(II) was studied in batch reactors in which the concentration of Fe(III) was in the range of 0–600 mg/l. The oxygenation rate increased linearly with the increasing Fe(III) concentrations up to 50 mg/l and a second-order polynomial relationship was found between the reaction rate and the Fe(III) concentrations in the range of 50–600 mg/l. The required volume (V) of the aeration tank and the effluent Fe(II) concentrations were determined as a function of the Fe(III) concentration. The volume of the aeration tank required for the same Fe(II) conversion was reduced by a factor of 15 when the Fe(III) concentration was raised from 0 to 600 mg/l at pH=6.7. No incremental benefit of the increase of Fe(III) concentration was observed at Fe(III) levels beyond the 600 mg/l. This study has experimentally demonstrated that significant savings can be achieved in iron removal systems by recirculating the Fe(III) sludges back to the aeration tank.

Inhibition effect of ferric iron on the kinetics of ferrous iron

Ferric iron acted as a non-competitive inhibitor for the biological oxidation of ferrous iron and decreased the inhibitory effects of high concentrations of ferrous iron as well as the auto-inhibitive effect the bacterial cells. A previously developed kinetic model for this reaction was modified to incorporate the inhibition effects of ferric iron. © Rapid Science Ltd. 1998

Contribution of cytochrome P450 3A pathway to bromocriptine metabolism and effects of ferrous iron and hypoxia-re-oxygenation on its elimination in the perfused rat liver.

The contribution of the cytochrome P450 3A pathway to bromocriptine metabolism, and the effects of ferrous iron and hypoxia-re-oxygenation on its elimination, were evaluated with the perfused rat liver. Outflow profiles of bromocriptine after bolus administration were estimated by moment analysis and dispersion model analysis. Kinetic parameters were not significantly changed by troleandomycin, a P450 3A inhibitor. The inhibition of bromocriptine metabolism by troleandomycin was 5.7 +/- 2.4%. These findings indicate that cytochrome P450 3A does not play an important role in bromocriptine elimination with the perfused rat liver. Elimination rate constant (ka) values were significantly increased by ferrous iron perfusion or hypoxia-re-oxygenation. Free-radical generation can, therefore, affect bromocriptine elimination. Our observations suggest that bromocriptine might be eliminated by scavenging of free radicals in the liver.

Binding of Iron to Neuromelanin of Human Substantia Nigra and Synthetic Melanin: An Electron Paramagnetic Resonance Spectroscopy Study

The binding of iron by melanin is a potentially important phenomenon as detailed knowledge of this binding is essential for understanding the role of melanin and iron in the pathogenesis of oxidative damage in the substantia nigra. Electron paramagnetic resonance spectroscopy is one of the most useful approaches in the investigation of melanins and their interaction with iron. This study was undertaken to obtain systematic data on the effects of ferric iron on the electron paramagnetic resonance spectra of neuromelanin and synthetic models of neuromelanin. Data from the latter can potentially be used to infer as to the state of neuromelanin in the human substantia nigra. The results of this study indicate that the spectra at g = 4.3, attributable to Fe 3+, provides a useful parameter for determining the amount of paramagnetic iron bound to melanin. These data together with the magnitude of the free radical signal from melanin provides an indication of the amount of iron bound to neuromelanin in intact human substantia nigra. After binding to melanin, the iron can change its location and/or state, which is indicated by the change in the microwave power saturation that occurs gradually after the binding of the iron. At least part of this process could occur at low temperatures (i.e., during storage at −15°C). © 1997 Elsevier Science Inc.

Effect of ferrous iron on the generation of hydroxyl free radicals by liver microdialysis perfusion of salicylate

1. We applied in vivo microdialysis technique to examine the effect of Fe2+, Fe3+, Cu2+ and Zn2+ on free radical-generation of rat liver. The hydroxyl free radical (.OH) reacts with salicylate and generates 2,3- and 2,5-dihydroxybenzoic acid (DHBA) which can be measured electrochemically in picomole quantity by HPLC-EC procedure. 2. The relative rates of recovery of 2,3- and 2,5-DHBA at 1 microliter/min in vitro were an average of 10.1 +/- 0.8% and 10.5 +/- 9%, respectively. 3. When the metal ion infused through the dialysis probe, Fe2+ but not Fe3+, Cu2+ and Zn2+ caused an increase in the formation of DHBA of rat liver. 4. After the Ringer solution containing 10 mumole/kg was injected into the penile vein, the levels of 2,3- and 2,5-DHBA were increased about 60% and 40%, respectively. 5. These results indicate that non-enzymatic oxidation in the extracellular fluid may play a key role in Fe2+ generation of -OH in liver. Free radical formation processes may contribute to in vivo free radical formation induced by Fe2+.

The Effect of Ferrous Iron on Mineral Scaling During Oil Recovery.

The Effect of Ferrous Iron on Mineral Scaling During Oil Recovery.

The effects of ferrous iron, dissolved oxygen, and inert solids concentrations on the growth of thiobacillus ferrooxidans

AbstractThe effects of suspended, inert solids concentration, ferrous iron concentration and dissolved oxygen concentration on the kinetics of iron oxidation by Thiobucillus ferrooxidans are reported. It is shown that the maximum specific growth rate for this organism, oxidizing ferrous iron, is of the order of 0.1 h−1. Competitive inhibition by femc iron is demonstrated. The dissolved oxygen concentration below which the bacteria will not grow is 0.20 mg/L. The dissolved oxygen concentration below which O2 availability is limiting is around 0.29‐0.7 mg/L. 10.4 millimols of CO2 are fixed by the bacteria per mol of ferrous iron oxidized. 0.0185 mg of bacterial carbon are generated per mg of O2 consumed. Comparative mass transfer rates for O2 and CO2 are discussed. Oxidation rates decreased significantly in shake flasks as suspended solids concentrations rose above 0.5%, whereas in stirred tanks solids concentrations up to 15% had little effect on oxidation rate.

Effect of ferric iron and desferrioxamine on lipofuscin accumulation in cultured rat heart myocytes

The general objective of this study was to examine the role of oxidative stress and transition metal catalysis in lipofuscinogenesis in postmitotic cells. Effects of 30 μM ferric chloride and different concentrations of desferrioxamine, ranging from 12.5 to 50 μM, on lipofuscin content were examined in rat cardiac myocytes at 6 and 12 days of in vitro age, under 20% and 40% ambient oxygen concentration. Lipofuscin was quantified by microspectrofluorometry of individual cells. Using X-ray microanalysis, iron was found to be sequestered in the secondary lysosomes that also contain the fluorescent lipofuscin material. Augmentation of iron in the culture medium markedly increased the level of lipofuscin accumulation while desferrioxamine had the opposite effect. Both of these effects were more pronounced at higher oxygen tension. Iron and oxygen had a cumulative effect on lipofuscin accumulation. Results are interpreted to indicate that oxidative stress and iron, in loosely bound form, are causal factors in lipofuscinogenesis. The possibility of employing microspectrofluoometry of lipofuscin as an indicator of oxidative stress is emphasized.

Effects of ferrous iron and transferrin on cell proliferation of human diploid fibroblasts in serum-free culture.

Iron-free RITC 80-7 defined medium was used to examine effects of ferrous iron and transferrin on cell proliferation of human diploid fibroblasts. Both ferrous iron and holo-transferrin stimulated cell proliferation in the medium, but apotransferrin did not. When 5 g/l human serum albumin (HSA) was added to the defined medium, excellent growth was obtained under hypoxic conditions, whereas a reduction of cellular growth during the culture periods was observed under aerobic conditions. When ferrous iron was added to the HSA medium alone, the reduction in growth increased in proportion to the concentrations, whereas the addition of transferrin prevented this reduction in a concentration-dependent manner. This suggests that the ferrous iron concentration in media causes a reduction in growth under aerobic conditions and transferrin prevents this reduction because it decreases the ferrous iron concentration. Further, serum albumin seems to be a source of iron in media.