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PubMed1993

Reduction of radiocesium transfer to animal products using sustained release boli with ammoniumiron(III)-hexacyanoferrate(II).

A sustained release bolus with the cesium binder ammoniumiron(III)-hexacyanoferrate (AFCF) has been developed as a countermeasure for small ruminants grazing pastures contaminated by radiocesium (134Cs+137Cs). The boli (40-50 g) are produced by compression of a mixture of AFCF, barite and wax. The release of AFCF from boli labelled with 137Cs-iron-hexacyanoferrate complex was studied in laboratory sheep. The release rate followed first order kinetics during the 108 d of observation and decreased from 40 to 22, 110 to 35 and 280 to 25 mg d-1 in sheep treated with 1, 2 or 3 boli respectively. The efficiency of boli in reducing radiocesium transfer to meat and milk was tested in laboratory studies with goats fed 134Cs tracer. Until 40 d after treatment the transfer of radiocesium to milk was reduced by 35%, 60% and 85% in goats given 1, 2 or 3 boli, respectively. The reduction in radiocesium transfer persisted for 90 d but with a lower efficiency. A similar relationship was found between number of boli and the reduction in radiocesium transfer to meat with an observed maximal reduction of 60%.

Animals↗

PubMed1989

Countermeasures for reducing the transfer of radiocesium to animal derived foods.

The nuclear reactor accident in Chernobyl stimulated new discussions and experiments on the question, how and to what extent the radiocesium-concentration in animal derived foods can be reduced. In a brief review this paper describes the use of two groups of feed additives as already applied in laboratory experiments during the period of atmospheric atomic weapons tests to prevent radiocesium absorption in the gastro-intestinal tract: 1) Iron (III) -Hexacyanoferrates and 2) Clay minerals. In the post-Chernobyl-period pilot studies were initiated to test similar feed additives under practical farming conditions with "naturally" radiocesium-labeled feedstuffs. Since then it is obvious that the colloidal Prussian blue analogue Ammonium-Ferric-Cyanoferrate (AFCF) can be considered as a leading antidote against radiocesium, while Bentonite or Bolus alba are 88-266 times less effective, when compared on a weight basis. Additionally clay materials cause losses of minerals and trace elements and pose logistic problems when feeding millions of large animals. Because of the small doses needed AFCF appears as a substance of choice to reduce radiocesium burdens in animal derived foods, which gained full recognition by health authorities in W-Germany and Austria supported by an official clearance for the use as feed additive.

Accidents↗

PubMed1999

234Th and 7Be as tracers for transport and sources of particle-associated contaminants in the Hudson River Estuary.

The natural radionuclides 234Th and 7Be have known sources in estuaries and strongly and rapidly associate with particles. They are thus good tracers of the transport and sources of particles in the suspended sediment reservoir, and, by implication, of particle-associated contaminants such as heavy metals. In the Hudson River estuary, 234Th is produced from decay of dissolved 238U, which varies linearly with salinity, while 7Be is added directly to the estuary from the atmosphere. The 234Th/7Be activity ratio eliminates variations in radionuclide specific activities that result from changes in sediment grain size or composition. Sampling in the Hudson under conditions of low and high river flow shows that 234Th/7Be in suspended sediment increases from low salinity to higher salinity waters at all sampling times. The Th/Be activity ratio may thus be used as a tracer of where particles are labeled with these radionuclides in the estuary and of the relative importance of resuspension and particle transport through the estuary. The distribution of heavy metals in the suspended sediment reservoir can be compared with that of 234Th/7Be by normalizing the metals to Fe. Iron and Al are well correlated in suspended sediments of the Hudson, indicating that either element can be used to normalize grain size effects on specific concentrations of metals. Ratios of Ag and Pb to Fe in suspended particles generally increase down-estuary at all sampling times, whereas Cu, Zn and Cd-to-Fe ratios show more scatter and less consistency in trends. Both source(s) and chemical behavior affect the metal/Fe ratios. The strongest positive correlation with 234Th/7Be is seen for Ag/Fe, reflecting the dominance of lower estuary sources of this trace metal to the Hudson. Relationships between Pb/Fe, Cu/Fe and 234Th/7Be are less strong, reflecting multiple sources of these elements. No correlation is seen for Cd/Fe with 234Th/7Be, indicating either a source up-river or release of Cd as its Kd decreases with increasing salinity.

Beryllium↗

PubMed1975

Biogenesis of erythrocyte membrane proteins. In vitro studies with rabbit reticulocytes.

The capability of rabbit reticulocytes to synthesize red cell membrane proteins has been tested in vitro. Reticulocyte-rich blood from phenylhydrazine-treated rabbits was incubated in vitro in a complete amino acid medium containing ferrous salts, glucose, rabbit plasma and [3-H]leucine. Red cell ghost membranes were prepared by hypotonic lysis and leucine incorporation into hemoglobin and total membrane proteins determined. The pattern of incorporation into individual peptides was determined by polyacrylamide gel electrophoresis of labeled membranes on large (19 mm) gels which were then sliced into 1 mm sections; radioactivity was compared with densitometric tracings of Coomassie blue stained analytical (6 mm) gels. Incorporation of [3-H]leucine into both hemoglobin and membrane protein was linear over 1 h. Gel analysis of labeled membranes revealed that the amino acid was primarily incorporated into peptides with molecular weights of 90 000 or less; three peptides of molecular weights 90 000, 60 000 and 33 000 showed the highest specific activity. Synthesis of the four largest peptide species was negligible. Removable of ferrous salts inhibited synthesis of both globin and membrane protein equally (approx. 50%). However, puromycin and cycloheximide preferentially inhibited the synthesis of globin as compared to membrane proteins. Reticulocytes remain capable of synthesizing a number of membrane proteins; these results are consistent with studies of red cell membrane synthesis in anemic rabbits in vivo.

Anemia↗

PubMed2000

Enhanced nitrogenase activity in strains of Rhodobacter capsulatus that overexpress the rnf genes.

In the photosynthetic bacterium Rhodobacter capsulatus, a putative membrane-bound complex encoded by the rnfABCDGEH operon is thought to be dedicated to electron transport to nitrogenase. In this study, the whole rnf operon was cloned under the control of the nifH promoter in plasmid pNR117 and expressed in several rnf mutants. Complementation analysis demonstrated that transconjugants which integrated plasmid pNR117 directed effective biosynthesis of a functionally competent complex in R. capsulatus. Moreover, it was found that strains carrying pNR117 displayed nitrogenase activities 50 to 100% higher than the wild-type level. The results of radioactive labeling experiments indicated that the intracellular content of nitrogenase polypeptides was marginally altered in strains containing pNR117, whereas the levels of the RnfB and RnfC proteins present in the membrane were four- and twofold, respectively, higher than the wild-type level. Hence, the enhancement of in vivo nitrogenase activity was correlated with a commensurate overproduction of the Rnf polypeptides. In vitro nitrogenase assays performed in the presence of an artificial electron donor indicated that the catalytic activity of the enzyme was not increased in strains overproducing the Rnf polypeptides. It is proposed that the supply of reductants through the Rnf complex might be rate limiting for nitrogenase activity in vivo. Immunoprecipitation experiments performed on solubilized membrane proteins revealed that RnfB and RnfC are associated with each other and with additional polypeptides which may be components of the membrane-bound complex.

Bacterial Proteins↗

PubMed1996

Association between uteroferrin, retinol-binding protein, and transferrin within the uterine and conceptus compartments during pregnancy in swine.

The association between uteroferrin (UF, measured as acid phosphatase [AP] activity), retinol-binding protein (RBP), and transferrin (TF), within the intrauterine environment during the estrous cycle and pregnancy was examined. Pregnant gilts were killed on Days 7, 10, 13, 16, 19, 25, 30, 40, 50, 60, 70, 80, and 90. Cyclic gilts were killed on Days 7, 10, 13, and 16. On Days 7 through 19, each uterine horn was flushed with 20 ml Minimum Essential Medium. On Days 25 through 90, serum and allantoic fluid samples were collected from each fetus within each gilt and pooled for each gilt. Uterine flushings, allantoic fluid, and fetal serum samples were assayed for AP, RBP, and TF. Endometrium was collected from all gilts and cultured with [3H]-leucine; conditioned medium was measured for nondialyzable radioactive macromolecules, AP, and RBP. In uterine flushings, AP, RBP, and TF were low on Day 7, and then increased markedly (p < 0.01) by Day 13 in both cyclic and pregnant gilts. After log transformation of the data, AP was highly correlated with RBP (r = 0.99) and TF (r = 0.91, p < 0.01). Secretion of RBP and AP by endometrium in culture also increased (p < 0.01) during this period and was similar in cyclic and pregnant gilts, and RBP and AP secretion were highly correlated (r = 0.65, p < 0.01). Endometrial tissue did not secrete detectable amounts of TF in culture. Concentrations of all three proteins were low in allantoic fluid on Day 25, after which time they increased to Day 40, and then either stabilized to Day 70 followed by a decrease to Day 90 (AP and TF) or decreased to Day 90 (RBP). Endometrial secretion of both AP and RBP increased between Day 25 and 30. Then, AP increased further to Day 40 and did not change to Day 60, while RBP did not change from Day 30 to Day 60. Both decreased from Day 60 to 70, did not change to Day 80, and then increased again to Day 90. The association of RBP and TF concentrations with AP in various maternal and conceptus compartments during pregnancy is consistent with the hypothesis that one function of these two proteins may be to protect maternal and fetal tissues from lipid peroxidation that is a possible consequence of iron transport via endometrial secretion of UF.

Acid Phosphatase↗

PubMed1972

Synthesis of pulcherriminic acid by Bacillus subtilis.

The pathway of pulcherriminic acid synthesis in Bacillus subtilis strains AM and AM-L11 (a leucine-requiring auxotroph) was investigated. Determinations of radioactivity in pulcherriminic acid synthesized by cells growing in media containing (14)C-labeled amino acids indicated that B. subtilis produced pulcherriminic acid from l-leucine. The organism utilized the carbon skeletons of two l-leucine molecules to synthesize one molecule of pulcherriminic acid. Similar results were obtained with starved cell suspensions. Growing cells formed significant amounts of pulcherriminic acid only in media including a carbohydrate such as starch. However, carbohydrate carbon was not required for the synthesis of pulcherriminic acid molecules. Data obtained with cell suspensions supported the hypothesis that cyclo-l-leucyl-l-leucyl is an intermediate in pulcherriminic acid biosynthesis and indicated that molecular oxygen is required for the conversion of cyclo-l-leucyl-l-leucyl to pulcherriminic acid. A pathway for the synthesis of pulcherrimin from l-leucine in B. subtilis is proposed.

Aerobiosis↗

PubMed1996

Effect of natural antioxidant tanshinone II-A on DNA damage by lipid peroxidation in liver cells.

Tanshinone II-A (TSII-A) isolated from the root of Salvia miltorrhiza Bunge, a traditional medicine in China, is a derivative of phenanthrenequinone, which is known to have antioxidant properties. In the present study, effects of TSII-A on DNA damage by lipid peroxidation were investigated using liver cells, labeled with [3H] arachidonic acid, in the presence of FeCl2-DTPA. The results show that the nuclear DNA isolated from treated cells had higher radioactivity compared to controls and the radioactivity increased with longer incubation times. Purified lipid-DNA adducts had a characteristic fluorescent spectra and showed a decrease of hyperchromicity and melting point. TSII-A could inhibit the association of peroxidation products with DNA in liver cells and prevent a decrease in cell viability and in the the activity of O6-methylguanine acceptor protein with increasing incubation time. Compared with other antioxidants, TSII-A had a higher inhibitory ratio, which was similar to vitamin E and butylated hydroxy-toluene (BHT), but markedly stronger than NaN3, mannatol, and superoxide dismutase (SOD). These data suggest that TSII-A represents a new and effective antioxidant that inhibits the association of lipid peroxidation products with DNA. Its protective effect may be through breaking the chain reactions of peroxidation by scavenging lipid free radicals, thereby decreasing their cytotoxicity.

Abietanes↗

PubMed1989

Xanthine oxidase activity in rat pulmonary artery endothelial cells and its alteration by activated neutrophils.

The possibility that endothelial cell-derived oxidants could contribute to neutrophil-mediated endothelial cell injury and cytotoxicity has been a subject of speculation. Rat pulmonary artery endothelial cells (RPAECs) were examined for the presence of xanthine oxidase (XO) activity, a well-known source of O2-. Using a sensitive assay based on measurements of radioactive xanthine conversion to uric acid by high performance liquid chromatography (HPLC), RPAEC extracts were found to contain both XO and xanthine dehydrogenase (XD) activities. Extracts from early passage cells have 55.3 +/- 11.7 (mean +/- SE) units/10(6) cells of total (XO + XD) activity, one unit of activity being defined as the conversion of 1% of substrate to product in 30 minutes of incubation. XO comprised 31.6 +/- 3.1% of this total activity. Addition of human neutrophils stimulated with phorbol myristate acetate (PMA) caused a rapid and dose-dependent increase in RPAEC XO activity from 31.6 +/- 3.1% to 71.7 +/- 4.8% of total without altering total (XO + XD) activity. The neutrophil dose-response curve for increase in XO paralleled closely the curve for neutrophil-mediated RPAEC cytotoxicity. The basal XO and XD activities and the neutrophil-induced increase in XO activity were inhibited by treating RPAECs with allopurinol, oxypurinol, and lodoxamide, which also inhibited cytotoxicity, but not by catalase, superoxide dismutase, or deferoxamine. Addition of H2O2 failed to cause an increase in RPAEC XO activity or XD to XO conversion. The results suggest that during neutrophil-mediated injury, rapid conversion of RPAEC XD to XO occurs, resulting in increased XO, catalyzed endogenous oxidant production, which may contribute to the oxidant burden in the killing mechanism initiated by activated neutrophils. Although the mechanism for conversion of XD to XO is uncertain, it appears that neutrophil-derived H2O2 is not sufficient to cause this phenomenon. Furthermore, neither O2- nor chelatable iron is required for neutrophil-induced XD to XO conversion. Supernatant fluids from activated neutrophils failed to induce XD to XO conversion in RPAECs. This in vitro system provides an opportunity to define the cellular and molecular mechanisms underlying the in vivo phenomenon of XD to XO conversion associated with ischemic/reperfusion or inflammatory tissue injury.

Allopurinol↗

PubMed1996

Isolation, cloning, sequence analysis and localization of the operon encoding dimethyl sulfoxide/trimethylamine N-oxide reductase from Rhodobacter capsulatus.

The operon encoding the periplasmic enzymes dimethyl sulfoxide reductase (DMSOR) and trimethylamine N-oxide reductase (TMAOR) from the purple, non-sulfur, photosynthetic bacterium Rhodobacter capsulatus was isolated, cloned and sequenced, and its chromosomal location determined. It was shown by analytical and crystallographic data that DMSOR and TMAOR are identical enzymes. Degenerate primers were derived from short peptide sequences generated by automated Edman degradation and a 700 bp fragment was amplified by nested PCR, subsequently cloned and radioactively labeled to screen a prepared lambda DASH library. Positive lambda clones were subcloned into pBluescript and subsequently transformed into Escherichia coli to sequence the DMSOR/ TMAOR operon. The promoter consisted of an A + T-rich region followed by a -35 region, a putative ribosome binding site, and a leader sequence of 13 amino acid residues. The transcription terminator was a G + C-rich dyad sequence capable of forming a hairpin structure, which may act rho-independently. An optimized protein purification of the wild-type enzyme is also described, giving high yields (5 mg protein per liter of culture) and a specific activity of 30 units/mg. The molecular mass was determined by electrospray mass spectrometry to be 85,034 Da; from the deduced amino acid sequence the molecular mass of the apoenzyme was 85,033 Da.

Amino Acid Sequence↗

PubMed2003

Measurements of accelerator-produced leakage neutron and photon transmission through concrete.

Optimum shielding of the radiation from particle accelerators requires knowledge of the attenuation characteristics of the shielding material. The most common material for shielding this radiation is concrete, which can be made using various materials of different densities as aggregates. These different concrete mixes can have very different attenuation characteristics. Information about the attenuation of leakage photons and neutrons in ordinary and heavy concrete is, however, very limited. To increase our knowledge and understanding of the radiation attenuation in concrete of various compositions, we have performed measurements of the transmission of leakage radiation, photons and neutrons, from a Varian Clinac 2100C medical linear accelerator operating at maximum electron energies of 6 and 18 MeV. We have also calculated, using Monte Carlo techniques, the leakage neutron spectra and its transmission through concrete. The results of these measurements and calculations extend the information currently available for designing shielding for medical electron accelerators. Photon transmission characteristics depend more on the manufacturer of the concrete than on the atomic composition. A possible cause for this effect is a non-uniform distribution of the high-density aggregate, typically iron, in the concrete matrix. Errors in estimated transmission of photons can exceed a factor of three, depending on barrier thickness, if attenuation in high-density concrete is simply scaled from that of normal density concrete. We found that neutron transmission through the high-density concretes can be estimated most reasonably and conservatively by using the linear tenth-value layer of normal concrete if specific values of the tenth-value layer of the high-density concrete are not known. The reason for this is that the neutron transmission depends primarily on the hydrogen content of the concrete, which does not significantly depend on concrete density. Errors of factors of two to more than ten, depending on barrier thickness, in the estimated transmission of neutrons through high-density concrete can be made if the attenuation is scaled by density from normal concrete.

Air Pollutants, Radioactive↗

PubMed2001

Investigation of irradiated soil byproducts.

The high dose irradiation of windblown soil deposited onto the surface of spent nuclear fuel is of concern to long-term fuel storage stability. Such soils could be exposed to radiation fields as great as 1.08 x 10(-3) C/kg-s (15,000 R/hr) during the 40-year anticipated period of interim dry storage prior to placement at the proposed national repository. The total absorbed dose in these cases could be as high as 5 x 10(7) Gy (5 x 10(9) rads). This investigation evaluated the potential generation of explosive or combustible irradiation byproducts during this irradiation. It focuses on the production of radiolytic byproducts generated within the pore water of surrogate clays that are consistent with those found on the Idaho National Engineering and Environmental Laboratory. Synthesized surrogates of localized soils containing combinations of clay, water, and aluminum samples, enclosed within a stainless steel vessel were irradiated and the quantities of the byproducts generated measured. Two types of clays, varying primarily in the presence of iron oxide, were investigated. Two treatment levels of irradiation and a control were investigated. An 18-Mev linear accelerator was used to irradiate samples. The first irradiation level provided an absorbed dose of 3.9 x 10(5)+/-1.4 x 10(5)Gy (3.9 x 10(7)+/-1.4 x 10(7) rads) in a 3-h period. At the second irradiation level, 4.8 x 10(5)+/-2.0 x 10(5)Gy (4.8 x 10(7)+/-2.0 x 10(7) rads) were delivered in a 6-h period. When averaged over all treatment parameters, irradiated clay samples with and without iron (III) oxide (moisture content = 40%) had a production rate of hydrogen gas that was a strong function of radiation-dose. A g-value of 5.61 x 10(-9)+/-1.56 x 10(-9) mol/J (0.054+/-0.015 molecules/100-eV) per mass of pore water was observed in the clay samples without iron (III) oxide for hydrogen gas production. A g-value of 1.07 x 10(-8)+/-2.91 x 10(-9) mol/J (0.103+0.028 molecules/100-eV) per mass of pore water was observed in the iron (III) oxide containing clay samples for hydrogen gas production. This value was noticeably larger when the samples were spiked with both KCl and KNO3 salts. The ratio of oxygen to nitrogen gas was observed to increase as a function of absorbed dose particularly in the presence of both KCl and KNO3 salts. The creation of radiolytic byproducts produced an observable but small increase in headspace pressure. Temperature increases during irradiation were not observed. Additionally, KCl and KNO3 salts added to the clays enhanced nitrite production as a function of radiation-dose and the type of clay considered. The addition of aluminum to these samples had no statistically discernable impact at the alpha = 0.05 level. Generation of the irradiation products, hydrogen peroxide and hydrogen gas also depended upon the type of clay irradiated and the presence of both KCl and KNO3 salts and the total dose received.

Aluminum↗

PubMed1985

Technique of labeling monocytes with 111In-Fe colloid for use in humans.

In order to follow monocyte kinetics in hematologic malignancies by means of radioactive labeling, three conditions are necessary: (a) no loss of monocytes during separation, (b) specific labeling of monocytes, and (c) normal functional capacities of the labeled monocytes. In this report a method is described that fulfills the first two conditions and can be executed with maintenance of sterility. Cell labeling was performed using a mononuclear cell suspension consisting of monocytes (20%-50%), lymphocytes (50%-80%), and with minor contamination by granulocytes, thrombocytes, and erythrocytes. This cell suspension was obtained by centrifugation of a leukocyte suspension on a gradient of 16% wt/vol and 22% wt/vol human serum albumin solutions. The recovery of monocytes with this enrichment method approached 100%. Monocytes were labeled by endocytosis of 111In-Fe colloid; monocytes were labeled significantly higher than lymphocytes (P less than 0.001) and granulocytes (P less than 0.01) (Wilcoxon's two-sample test). Cell viability after labeling was greater than 90%.

Autoradiography↗

PubMed2006

Suspension array analysis of 16S rRNA from Fe- and SO(4)2- reducing bacteria in uranium-contaminated sediments undergoing bioremediation.

A 16S rRNA-targeted tunable bead array was developed and used in a retrospective analysis of metal- and sulfate-reducing bacteria in contaminated subsurface sediments undergoing in situ U(VI) bioremediation. Total RNA was extracted from subsurface sediments and interrogated directly, without a PCR step. Bead array validation studies with total RNA derived from 24 isolates indicated that the behavior and response of the 16S rRNA-targeted oligonucleotide probes could not be predicted based on the primary nucleic acid sequence. Likewise, signal intensity (absolute or normalized) could not be used to assess the abundance of one organism (or rRNA) relative to the abundance of another organism (or rRNA). Nevertheless, the microbial community structure and dynamics through time and space and as measured by the rRNA-targeted bead array were consistent with previous data acquired at the site, where indigenous sulfate- and iron-reducing bacteria and near neighbors of Desulfotomaculum were the organisms that were most responsive to a change in injected acetate concentrations. Bead array data were best interpreted by analyzing the relative changes in the probe responses for spatially and temporally related samples and by considering only the response of one probe to itself in relation to a background (reference) environmental sample. By limiting the interpretation of the data in this manner and placing it in the context of supporting geochemical and microbiological analyses, we concluded that ecologically relevant and meaningful information can be derived from direct microarray analysis of rRNA in uncharacterized environmental samples, even with the current analytical uncertainty surrounding the behavior of individual probes on tunable bead arrays.

Bacteria↗

PubMed1992

Determination of plutonium-239 + plutonium-240 and plutonium-241 in environmental samples using low-level liquid scintillation spectrometry.

A radiochemical method for the simultaneous determination of 239Pu + 240Pu and 241Pu in environmental samples has been developed. In the course of the analysis a 236Pu tracer was used for estimating the chemical yield of plutonium isotopes. After suitable pre-treatment of the sample, the plutonium nuclides in solution were coprecipitated with iron(III) hydroxide and calcium oxalate and isolated further from impurities and interfering radionuclides by means of anion-exchange chromatography. Plutonium isotopes in the eluate (NH4I-HCI) were converted into nitrate form and then extracted with 20 ml of 5% bis(2-ethylhexyl) hydrogen phosphate extractive cocktail. The final organic solution was measured spectrometrically using an ultra-low-level liquid scintillation spectrometer, Quantulus (LKB, 1220 Wallac). The chemical yields of plutonium range from 25 to 50% for 100 I of sea-water and 30 to 60% for 40 g of dried soil sample. The counting efficiencies are nearly 100% for 239Pu + 240Pu and 48.8% for 241Pu, respectively. The detection limits were estimated to be 0.20 mBq for 239Pu + 240Pu and 2.2 mBq for 241Pu, respectively. The proposed procedure has been tested for the simultaneous determination of 239Pu + 240Pu and 241Pu in sea-water (Irish Sea, North Sea) and soils (Cumbrian coast, UK; Byelorussia, USSR).

Europe↗

PubMed2006

Peptide-based phosphoproteomics with immobilized metal ion chromatography.

The identification of protein phosphorylation sites has always been a challenging task, traditionally involving large amounts of radioactive phosphorus and high-performance liquid chromatography separation and Edman sequencing of phosphopeptides. The rapid development of mass spectrometric methods has advanced protein research significantly, and the identification of in vivo post-translational modifications of even rare proteins is now possible. Even with the new generation of machines, however, phosphopeptides do not lend themselves easily to mass spectrometric analysis. In complex mixtures of peptides, phosphopeptides are often difficult to detect because of suppression effects during ionization. This problem can be largely solved by affinity purification/enrichment of the phosphopeptides, and immobilized metal ion affinity chromatography (IMAC) on chelated Fe3+ or other metal ions has emerged as the simplest and most useful method. IMAC has been useful to identify several in vivo phosphorylation sites of individual proteins, but is easier to apply to complex mixtures. We describe a complete protocol as it has been used for Arabidopsis plasma membranes, and note where it can be adapted for soluble protein mixtures.

Arabidopsis↗

PubMed1976

Red blood cell metabolism in AKR mice in the prelymphomatous phase.

The purpose of this study was to evaluate erythrokinetics and in vitro red blood cell (RBC) glucose utilization, 2,3-diphosphoglycerate production, and adenosine triphosphate levels following incubation in AKR mice from early in life until the onset of AKR lymphoma. Normal BALB/c mice served as controls. While hemoglobin concentration and RBC survival remained constant and similar in both groups of mice, the half disappearance time of injected radioactive 59Fe was longer and the 48-hr reappearance of 59Fe was less in AKR mice, compared with those of BALB/c mice. In vitro RBC metabolic studies indicated increased glucose utilization and 2,3-diphosphoglycerate production and decreased adenosine triphosphate levels following incubation in AKR RBC, in contrast to those in BALB/c RBC. RBC metabolic studies were also done in a small group of low leukemic C3H mice, and were similar to BALB/c mice. These differences became most marked in RBC from mice aged 15 to 30 weeks. Overt lymphoma began to occur after age 40 weeks. Hence, these erythropoietic changes occurred prior to the onset of lymphoma. The data imply a direct effect of virus infection on RBC or their precursors. The results are similar to changes in RBC metabolism noted in Rauscher-infected BALB/c mice. The broader implication of these findings in reference to viral host interactions and human leukemogenesis is discussed.

Adenosine Triphosphate↗

PubMed2003

Carbonate effects on hexavalent uranium adsorption by iron oxyhydroxide.

Carbonate dramatically affects the adsorption of uranium (U(VI)) onto iron hydroxides and its mobility in the natural environment. Batch tests, zeta potential measurements, and Fourier transform infrared (FTIR) spectroscopic studies were utilized to characterize the nature of U(VI) adsorption on ferrihydrite. Adsorption isotherms demonstrated that carbonate had a negative effect on U(VI) adsorption on ferrihydrite at pH > 6. Zeta potential measurements indicated that U(VI) was adsorbed as a cationic species (SO-UO2+) in the absence of carbonate and as anionic U(VI) complexes in the presence of carbonate at neutral pH. FTIR spectroscopic measurement of adsorbed U(VI) suggested that it was retained as uranyl carbonate complexes in the presence of carbonate. An increase in carbonate concentration caused a shift in the antisymmetric stretching vibration of the uranyl (UO2(2+)) U-O bond toward lower wavenumbers, which indicated an increasing carbonate effect in the adsorbed uranyl carbonate complexes. The adsorbed U(VI) species were successfully incorporated into a surface complexation model to describe the adsorption of U(VI) by ferrihydrite from artificial solutions and contaminated water.

Adsorption↗