Acquired resistance to acute renal failure in ischemic and uranium-induced renal failure of rabbits.
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Acute Kidney Injury↗
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Results for “Uranium Compounds”
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The effect of osmium postfixation and uranyl and lead staining on the ultrastructure of young enamel in the rat incisor.
Enamel crystallites are electron opaque without osmium or heavy metal staining and give a crystalline electron diffraction pattern. Since the opacity and diffraction pattern are abolished from ultrathin sections of young enamel by floating on distilled water (Bishop and Warshawsky, 1982), the possibility that aqueous staining may also remove crystallites was tested. In addition, the effect of osmium postfixation on crystallite structure was examined. Rat incisors fixed by perfusion with a mixture of aldehydes were either nonosmicated or osmicated prior to dehydration. Incisor segments in the region of inner enamel secretion were embedded in the same Epon block to ensure reliable comparison. Osmicated enamel was more intensely stained with toluidine blue and more electron opaque than nonosmicated enamel. No other structural differences were seen. However, crystallites in osmicated enamel were more resistant to grid demineralization and electron beam damage. Routine staining was done by floating sections on solutions of uranyl acetate and lead citrate; sections were also floated on similar solutions from which the heavy metals were omitted. These solutions removed the electron opaque crystallites from the youngest enamel. Stained sections showed electron opaque crystallite-like structures similar to unstained enamel. When sections that were extracted by the solutions from which the metals were omitted were restained, they appeared identical to routinely stained enamel. It was concluded that staining of young enamel removes the crystallites and reveals only the organic matrix.
Aging↗
Study of negatively stained images of Sendai virus nucleocapsids using minimum-dose system.
Using minimum-dose system and optical diffraction, effects of electron irradiation on negatively stained images of trypsin-straightened nucleocapsids of Sendai virus were semiquantitatively compared for uranyl-acetate (UA) and phosphotungstic acid (PTA). The results confirmed the superiority of UA in display of fine structures and showed that both UA- and PTA-stained images tended to turn from a one-sided to a two-sided image during irradiation, the general contrast of the picture increased in the UA-stained images but not in the PTA-stained ones, and furthermore the electron doses for the richest information were 18 000 to 30 000 e-/nm2 for UA, but 1000 e-/nm2 for PTA, under the condition used. The optical diffraction patterns of the UA-stained nucleocapsids, its analysis by the superposition method, and rotational harmonics of end-on views of nucleocapsids, together indicated that the most probable arrangement of subunits was 13 per turn of a helix with 5-nm periodicity. This helix also had an arrangement of subunits parallel to the axis. The occurrence of 2.5 nm periodicity was probably produced by an arrangement of a UA-penetrable concave substructure of the subunit.
Capsid↗
226Ra/238U disequilibrium in an upland organic soil exhibiting elevated natural radioactivity.
This paper presents the results of a study into the anomalous 226Ra/238U disequilibrium (226Ra/238U of 0.5-9) exhibited by an upland organic soil in Co. Donegal, Ireland. Radiochemical speciation of 226Ra, 238U and 225Ra indicates that in this organic soil the high 226Ra/238U ratio is due to loss of 235U relative to 226Ra via oxidation and mobilisation of 238U in the upper layers of the soil and subsequent loss in solution. At the lower, more reducing depths of the soil profile, 238U and 226Ra are essentially in equilibrium. Loss of 238U appears to occur primarily from the easily oxidised organic and iron oxide fractions of the soil, samples exhibiting high 226Ra/238U ratios displaying significantly lower 238U levels in these fractions than samples whose ratio is below the average value for the soil of the valley. Selective enrichment of 226Ra by plants or preferential leaching of 226Ra from the underlying rock is not supported by the results of this study.
Ferric Compounds↗
Role for Fe(III) minerals in nitrate-dependent microbial U(IV) oxidation.
Microbiological reduction of soluble U(VI) to insoluble U(IV) is a means of preventing the migration of that element in groundwater, but the presence of nitrate in U(IV)-containing sediments leads to U(IV) oxidation and remobilizaton. Nitrite or iron(III) oxyhydroxides may oxidize U(IV) under nitrate-reducing conditions, and we determined the rate and extent of U(IV) oxidation by these compounds. Fe(III) oxidized U(IV) at a greater rate than nitrite (130 and 10 microM U(IV)/day, respectively). In aquifer sediments, Fe(III) may be produced during microbial nitrate reduction by oxidation of Fe(II) with nitrite, or by enzymatic Fe(II) oxidation coupled to nitrate reduction. To determine which of these mechanisms was dominant, we isolated a nitrate-dependent acetate- and Fe(ll)-oxidizing bacterium from a U(VI)- and nitrate-contaminated aquifer. This organism oxidized U(IV) at a greater rate and to a greater extent under acetate-oxidizing (where nitrite accumulated to 50 mM)than under Fe(II)-oxidizing conditions. We showthatthe observed differences in rate and extent of U(IV) oxidation are due to mineralogical differences between Fe(III) produced by reaction of Fe(II) with nitrite (amorphous) and Fe(III) produced enzymatically (goethite or lepidocrocite). Our results suggest the mineralogy and surface area of Fe(III) minerals produced under nitrate-reducing conditions affect the rate and extent of U(IV) oxidation. These results may be useful for predicting the stability of U(IV) in aquifers.
Acetates↗
Wetting agents for biological electron microscopy. I. General considerations and negative staining.
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Acetates↗
[Effect of the isolation method and staining procedure on the morphology of the virion ribonucleoprotein of Sendai virus].
Electron microscopic examinations of morphology of Sendai virus ribonucleoprotein (RNP) isolated from purified virions by two methods and simultaneous staining of the preparations with uranyl acetate and phosphotungstate acid (PTA) were carried out. The staining method was shown not to influence the kind of nucleoproteins which had been isolated from disrupted virions by sucrose density gradient centrifugation. With both strains RNP appeared as strongly helixed filaments. The staining method, however, strongly influenced morphology of RNP isolated from disrupted virions by equilibrium centrifugation in cesium chloride density gradient. After uranyl acetate staining RNP had an appearance of hard filaments whereas in the same preparation stained with PTA partially and completely unwound spirals of nucleocapsid were found alongside with strongly spiralized structures.
Centrifugation, Density Gradient↗
Reoxidation of reduced uranium with iron(III) (hydr)oxides under sulfate-reducing conditions.
In cultures of Desulfovibrio desulfuricans 620 the effects of iron(III) (hydr)oxides (hematite, goethite, and ferrihydrite) on microbial reduction and reoxidation of uranium (U) were evaluated under lactate-limited sulfate-reducing conditions. With lactate present, G20 reduced U(VI) in both 1,4-piperazinediethanesulfonate (PIPES) and bicarbonate buffer. Once lactate was depleted, however, microbially reduced U served as an electron donor to reduce Fe(III) present in iron(III) (hydr)oxides. With the same initial amount of Fe(III) (10 mmol/L) for each iron(III) (hydr)oxide, reoxidation of U(IV) was greater with hematite than with goethite orferrihydrite. As the initial mass loading of hematite increased from 0 to 20 mmol of Fe(III)/L, the rate and extent of U(IV) reoxidation increased. Subsequent addition of hematite [15 mmol of Fe(III)/L] to stationary-phase cultures containing microbially reduced U(IV) also resulted in rapid reoxidation to U(VI). Analysis by U L3-edge X-ray absorption near-edge spectroscopy (XANES) of microbially reduced U particles yielded spectra similar to that of natural uraninite. Observations by high-resolution transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray spectroscopic analysis confirmed that precipitated U associated with cells was uraninite with particle diameters of 3-5 nm. By the same techniques, iron sulfide precipitates were found to have a variable Fe and S stoichiometry and were not associated with cells.
Alkanesulfonic Acids↗
Preparation and crystal structure of the ternary uranium rare Earth antimonides (U(2/3)R(1/3))Sb(2) and (U(1/2)R(1/2))(3)Sb(7) with mixed U/R occupancy of the metal sites and a variety of antimony polyanions.
The ternary antimonides (U(2/3)R(1/3))Sb(2) (R = Y, Ce-Nd, Sm, Gd-Tm) and (U(1/2)R(1/2))(3)Sb(7) (R = Y, Gd-Ho) have been prepared by reaction of the uranium antimonide USb(2) with the corresponding rare earth antimonides RSb(2) and an excess of elemental antimony at high temperatures. The crystal structure of the isotypic series (U(2/3)R(1/3))Sb(2) has been determined from single-crystal X-ray data of (U(0.675(9))Gd(0.325(9)))Sb(2). It is isotypic with PbCl(2): Pnma, Z = 4, a = 754.6(1), b = 419.6(1), c = 1025.7(3) pm. The compounds of the other series crystallize with a new structure type, which has been determined for (U(0.49(1))Ho(0.51(1)))(3)Sb(7): Immm, Z = 4, a = 410.1(1), b = 1447.7(3), c = 1821.2(5) pm. In both structures, the metal positions have mixed occupancy and high coordination numbers. Both structures contain numerous weak Sb-Sb bonds, thus forming a band of antimony atoms in the structure of (U(2/3)Gd(1/3))Sb(2) and a chain and a three-dimensionally infinite network of antimony atoms in the structure of (U(1/2)Ho(1/2))(3)Sb(7). Analyses of the Sb-Sb bonding within the antimony polyanions on the basis of bond-length bond-strength considerations indicate that the uranium atoms have mixed or intermediate +3/+4 valence in these compounds. The structure of (U(1/2)Ho(1/2))(3)Sb(7) may be considered as a defect variant of the structure of Ce(6)MnSb(15).
Journal Article↗
Molecular genetics of Thiobacillus ferrooxidans.
Thiobacillus ferrooxidans is a gram-negative, highly acidophilic (pH 1.5 to 2.0), autotrophic bacterium that obtains its energy through the oxidation of ferrous iron or reduced inorganic sulfur compounds. It is usually dominant in the mixed bacterial populations that are used industrially for the extraction of metals such as copper and uranium from their ores. More recently, these bacterial consortia have been used for the biooxidation of refractory gold-bearing arsenopyrite ores prior to the recovery of gold by cyanidation. The commercial use of T. ferrooxidans has led to an increasing interest in the genetics and molecular biology of the bacterium. Initial investigations were aimed at determining whether the unique physiology and specialized habitat of T. ferrooxidans had been accompanied by a high degree of genetic drift from other gram-negative bacteria. Early genetic studies were comparative in nature and concerned the isolation of genes such as nifHDK, glnA, and recA, which are widespread among bacteria. From a molecular biology viewpoint, T. ferrooxidans appears to be a typical member of the proteobacteria. In most instances, cloned gene promoters and protein products have been functional in Escherichia coli. Although T. ferrooxidans has proved difficult to transform with DNA, research on indigenous plasmids and the isolation of the T. ferrooxidans merA gene have resulted in the development of a low-efficiency electroporation system for one strain of T. ferrooxidans. The most recent studies have focused on the molecular genetics of the pathways associated with nitrogen metabolism, carbon dioxide fixation, and components of the energy-producing mechanisms.
Base Sequence↗
[Leaching of ores with heterotrophic microorganisms. Development of a screening method].
Besides leaching of sulfide ores with thiobacilli, a second way of microbial leaching is tested with carbon-heterotrophic fungi and bacteria for those types of ores, where thiobacilli fail to work. The active agents are metabolic products, f. i. organic acids, which are released into the medium producing water soluble compounds with heavy metals. A screening method is described for recognizing active strains in samples of soil, metal-containing sites, mining heaps and other biocoenoses, using the dilution method in plates with different media. The critical signs of supposed leaching activity are halo formations around growing colonies in turbid agar media with suspended particles of Ca carbonate or Ca phosphates of low solubility, and in a second group of experiments with insoluble compounds of heavy metals, f. i. oxides. The leaching activity was tested with metal compounds suspended in liquid media and inoculated with active strains of the screening program. First results were reached with oxides of copper (CuO), uranium (U3O8) and an uranium-containing phosphorite.
Bacteria↗
The carbohydrates of secretory granules and the glycocalyx in developing mucoid cells.
Complex carbohydrates in secretory granules and at the apical cell surface of mouse gastric mucoid cells were studied during embryogenesis and in the early postnatal period by various cytochemical methods; the periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) and tannic acid-uranyl acetate (TA-UA) procedures made neutral mucosubstances (NMS) visible, whereas the hexose residues of glycoconjugates were identified using WGA-, RCA II- and ConA-ferritin. The glycocalyx was stained with ruthenium red (RR). During differentiation of the embryonic mucoid cells the number of secretory granules increased in parallel to the increase in their carbohydrate component. NMS-stainable parts in secretory granules also had binding sites for the conjugates RCA II- and WGA-ferritin, but the binding of ConA could not be identified. The increasing quantity of NMS in secretory granules was correlated with the increased amount of PA-TCH-SP and TA-UA positive substances in the apical glycocalyx only in 14- and 18-day-old embryos. The observed uniform affinity for RR and lectin conjugates in all analysed developmental stages remains to be explained.
Animals↗
Electron microscopy of tRNA crystals. I. Thin crystals negatively stained with uranyl acetate.
The first attempt to study crystal structures of tRNA by electron microscopy is described. Sufficiently thin crystals were prepared from yeast tRNAphe. The thickness of the thinnest was estimated at 130 A corresponding to a bilayer of the molecules. The L-shaped structure seemed to be maintained even after the negative staining with uranyl acetate. Optically filtered images from electron micrographs were compared with those simulated from the drawing of the molecular model by optical transform. The results suggest that the observed images reflect the real molecular arrangements within the crystal lattice although the shape of tRNA molecules seems to be somewhat modified by the uneven staining.
Crystallography↗
[(CH3)4N][(C5H5NH)0.8((CH3)3NH)0.2]U2Si9O23F4 (USH-8): an organically templated open-framework uranium silicate.
The open-framework uranium fluorosilicate [(CH3)4N][(C5H5NH)0.8((CH3)3NH)0.2]U2Si9O23F4 (USH-8) has been synthesized hydrothermally by using tetramethylammonium hydroxide and pyridine-HF. The compound has a framework composition U2Si9O23F4 based on silicate double layers that are linked by chains of UO3F4 pentagonal bipyramids. The framework has 12-ring channels along [010] and 7-ring channels along [100]. The [010] 12-ring channels have a calabash-shape with the middle part partially blocked by the uranyl oxygen atoms. The narrow side of the 12-ring channels is occupied by well-ordered TMA cations while the wide side is occupied by disordered pyridinium and trimethylammonium cations.
Journal Article↗
Synthesis, structure, and photoelectronic effects of a uranium-zinc-organic coordination polymer containing infinite metal oxide sheets.
The hydrothermal reaction of ZnUO2(OAc)4.7H2O with pyridine-2,3-dicarboxylic acid gives rise to a novel uranium-zinc-organic coordination polymer containing infinite U-O-Zn double sheets and organic ligands. Thermal and photoelectrochemical analyses indicate that the coordination polymeric compound not only has a high thermal stability but also exhibits interesting photoelectronic properties.
Journal Article↗
[Photometric analysis with reaction between metal ion (M) and organic reagent (R)].
Firstly, the syntheses of various organic reagents (R) containing such xanthene derivatives as O-hydroxyhydro-quinonephthalein (QnPh), and 3,4,5,6-tetrahydroxyfluoran (gallein, Gall) were studied. Secondarily, the coexisting effects of surfactant (cationic-, anionic-, amphoteric- and nonionic-surfactants alone or combination) on the coloring or fluorescence reactions between various (R) such as xanthene derivatives, aromatic amines and various metal ions (M) such as bismuth(III), tin(IV), iron(III), molybdenum(VI), uranium(VI), cobalt(II), aluminum(III), etc. were systematically investigated. Thirdly, numerous simple and sensitive photometric analyses (spectrophotometry and fluorophotometry) for various (M) and organic compounds(Org) such as biological samples, and pharmaceutical preparations by formation reactions of (R-M) binary or ((R-M)-Org) ternary complexes were established in the coexistence of surfactant alone or combination.
Indicators and Reagents↗
Microbial reduction of U(VI) at the solid-water interface.
Microbial (Geobacter sulfurreducens) reduction of 0.1 mM U(VI) in the presence of synthetic Fe(III) oxides and natural Fe(III) oxide-containing solids was investigated in pH 6.8 artificial groundwater containing 10 mM NaHCO3. In most experiments, more than 95% of added U(VI) was sorbed to solids, so that U(VI) reduction was governed by reactions at the solid-water interface. The rate and extent of reduction of U(VI) associated with surfaces of synthetic Fe(III) oxides (hydrous ferric oxide, goethite, and hematite) was comparable to that observed during reduction of aqueous U(VI). In contrast, microbial reduction of U(VI) sorbed to several different natural Fe(III) oxide-containing solids was slower and less extensive compared to synthetic Fe(III) oxide systems. Addition of the electron shuttling agent anthraquinone-2,6-disulfonate (AQDS; 0.1 mM) enhanced the rate and extent of both Fe(III) and U(VI) reduction. These findings suggest that AQDS facilitated electron transfer from G. sulfurreducens to U(VI) associated with surface sites atwhich direct enzymatic reduction was kinetically limited. Our results demonstrate that association of U(VI) with diverse surface sites in natural soils and sediments has the potential to limit the rate and extent of microbial U(VI) reduction and thereby modulate the effectiveness of in situ U(VI) bioremediation.
Anthraquinones↗
Reduction of Fe(III), Cr(VI), U(VI), and Tc(VII) by Deinococcus radiodurans R1.
Deinococcus radiodurans is an exceptionally radiation-resistant microorganism capable of surviving acute exposures to ionizing radiation doses of 15,000 Gy and previously described as having a strictly aerobic respiratory metabolism. Under strict anaerobic conditions, D. radiodurans R1 reduced Fe(III)-nitrilotriacetic acid coupled to the oxidation of lactate to CO(2) and acetate but was unable to link this process to growth. D. radiodurans reduced the humic acid analog anthraquinone-2,6-disulfonate (AQDS) to its dihydroquinone form, AH(2)DS, which subsequently transferred electrons to the Fe(III) oxides hydrous ferric oxide and goethite via a previously described electron shuttle mechanism. D. radiodurans reduced the solid-phase Fe(III) oxides in the presence of either 0.1 mM AQDS or leonardite humic acids (2 mg ml(-1)) but not in their absence. D. radiodurans also reduced U(VI) and Tc(VII) in the presence of AQDS. In contrast, Cr(VI) was directly reduced in anaerobic cultures with lactate although the rate of reduction was higher in the presence of AQDS. The results are the first evidence that D. radiodurans can reduce Fe(III) coupled to the oxidation of lactate or other organic compounds. Also, D. radiodurans, in combination with humic acids or synthetic electron shuttle agents, can reduce U and Tc and thus has potential applications for remediation of metal- and radionuclide-contaminated sites where ionizing radiation or other DNA-damaging agents may restrict the activity of more sensitive organisms.
Anaerobiosis↗