Potential for biocolloid transport of cesium at high ionic strength.

In subsurface repositories, active bacterial populations may directly influence the fate and transport of radionuclides including in salt repository systems like the Waste Isolation Pilot Plant in Carlsbad, NM. This research quantified the potential for transport and interaction between Chromohalobacter sp. and Cs in a high ionic strength system (2.6 M NaCl) containing natural minerals. Mini-column experiments showed that Chromohalobacter moved nearly un-retarded under these conditions and that there was neither association of Cs with microbes nor dolomite despite changes in bacterial metabolic phases. Growth batch experiments that monitored the potential uptake of Cs into the microbes confirmed results in column experiments where intracellular uptake of Cs by Chromohalobacter was not observed. These results show that Cs may be highly mobile if released in high ionic strength systems and/or carbonate minerals with negligible inhibition by these microbes.

Removal of radioactive cesium from an aqueous solution via bioaccumulation by microalgae and magnetic separation.

We evaluated the potential sequestration of cesium (Cs+) by microalgae under heterotrophic growth conditions in an attempt to ultimately develop a system for treatment of radioactive wastewater. Thus, we examined the effects of initial Cs+ concentration (100-500 µM), pH (5-9), K+ and Na+ concentrations (0-20 mg/L), and different organic carbon sources (acetate, glycerol, glucose) on Cs+ removal. Our initial comparison of nine microalgae indicated that Desmodesmus armatus SCK had removed the most Cs+ under various environmental conditions. Addition of organic substrates significantly enhanced Cs+ uptake by D. armatus, even in the presence of a competitive cation (K+). We also applied magnetic nanoparticles coated with a cationic polymer (polyethylenimine) to separate 137Cs-containing microalgal biomass under a magnetic field. Our technique of combining bioaccumulation and magnetic separation successfully removed more than 90% of the radioactive 137Cs from an aqueous medium. These results clearly demonstrate that the method described here is a promising bioremediation technique for treatment of radioactive liquid waste.

Quantitative mapping of elements in basil leaves (Ocimum basilicum) based on cesium concentration and growth period using laser ablation ICP-MS.

Quantitative elemental mapping of metallic pollutants in sweet basil was studied by laser ablation (LA)-ICP-MS. For this, the sweet basil was cultivated in Hoagland nutrient solution spiked with 100 and 1000 ng mL-1 of Cs for 10-60 days. Then, the Cs distribution in collected leaves was determined by LA-ICP-MS using lab-synthesized standard pellets based on NIST 1573a tomato leaves. For comparison, S, Ca, and K were also simultaneously determined in this measurement with a13C+ signal from the leaves as an internal standard. The obtained calibration curves showed linear coefficient of determination (R2) of 0.991 for K and 0.999 for Cs. The concentration of Cs measured in the basil leaves increased with growth period and pollutant concentration, and accumulation followed the order of leaf margin, petiole, midrib, and veins. Although no visible symptom was detected, significant suppression of the growth rate was observed due to the presence of high-concentration Cs. The experimental model demonstrated herein showed potential for studying the influence of radioactive pollutants on plants and other organisms in the food chain.

The chemical toxicity of cesium in Indian mustard (Brassica juncea L.) seedlings.

To distinguish between the radiological and chemical effects of radiocesium, we study the chemical toxicity of cesium in the seedlings of Indian mustard (Brassica juncea L.). In this study, the experiment was designed in two factors and five levels random block design to investigate the interaction effects of Cs and K. Results showed that excessive Cs was one of the main factors influence the growth of Brassica juncea seedlings. And the toxicity of Cs in Brassica juncea is likely to be caused by Cs interacts with K-binding sites in essential K-dependent protein, either competes with K for essential biochemical functions, causing intracellular metabolic disturbance. To test the hypothesis that the toxicity of Cs might cause intracellular metabolic disturbance, next-generation sequencing (NGS)-based Illumina paired-end Solexa sequencing platform was employed to analysis the changes in gene expression, and understand the key genes in B. juncea seedlings responding to the toxicity of Cs. Based on the assembled de novo transcriptome, 2032 DEGs that play significant roles in the response to the toxicity of Cs were identified. Further analysis showed that excessive Cs is disturbance the auxin signal transduction pathway, and inhibited the indoleacetic acid-induced protein (AUX/IAA) genes expression eventually lead the seedlings growth and development be inhibited. The results suggest that disturbances to tryptophan metabolism might be linked to changes in growth.

Alginate enhances excretion and reduces absorption of strontium and cesium in rats.

Alginate (ALA), which is an intercellular polysaccharide associated with brown algae, is used as a food additive, a health food and a medicine. Here, we first examined the adsorption of strontium (Sr) and cesium (Cs) by ALA in vitro, and then evaluated the effects of ALA on absorption and excretion of Sr and Cs in rats, in order to evaluate its potential usefulness for minimizing radiation damage from materials released after a nuclear accident. Both Sr and Cs were concentration-dependently adsorbed by sodium alginate (ALA-Na) in vitro. In rats given diet containing either ALA-Na or calcium alginate (ALA-Ca) for two weeks, the plasma concentration of Sr gradually decreased compared with the controls (normal diet); however, in the case of Cs, the plasma concentration was decreased only in the ALA-Ca group, but not the ALA-Na group. Moreover, we examined the effect of preadministration of diet containing either ALA-Na or ALA-Ca on absorption of Sr and Cs administered orally as the chloride salts to rats. Absorption of both Sr and Cs was reduced in the ALA-Ca group, while absorption of only Sr was reduced in the ALA-Na group. Safety assessments indicated that ALA-Ca is safer than ALA-Na. These results indicate that ALA-Ca reduces absorption and promotes excretion of both Sr and Cs, while ALA-Na does so only for Sr.

Ionome of soybean seed affected by previous cropping with mycorrhizal plant and manure application.

Two field experiments were conducted to investigate the effects of previous cultivation of an arbuscular mycorrhizal (AM) host plant and manure application on the concentration of 19 mineral elements in soybean ( Glycine max L. Merr. cv. Tsurumusume) seeds. Each experiment ran for two years (experiment 1 took place in 2007-2008, and experiment 2 took place in 2008-2009) with a split plot design. Soybeans were cultivated after growing either an AM host plant (maize, Zea mays L. cv. New dental) or a non-AM host plant (buckwheat, Fagopyrum esculentum Moench. cv. Kitawase-soba) in the first year in the main plots, with manure application (0 and 20 t/ha) during the soybean season in split plots from both main plots. On the basis of the two experiments, manure application significantly increased the available potassium (K) and decreased the available iron (Fe) and cesium (Cs) in the soil. However, higher concentrations of cadmium (Cd) and barium (Ba) and lower concentrations of Cs in the seed were induced by the application of manure. Cd levels in the seed were decreased by prior cultivation with the AM host plant. The present study showed that the identity of the prior crop and manure application changed the mineral contents of the soybean seed and suggests a connection between environmental factors and food safety.

Evaluation of Cuprimine® and Syprine® for decorporation of radioisotopes of cesium, cobalt, iridium and strontium.

Cuprimine® and Syprine® are therapeutics approved by the USFDA to treat copper overload in Wilson Disease (a genetic defect in copper transport) by chelation and accelerated excretion of internally-deposited copper. These oral therapeutics are based on the respective active ingredients D-penicillamine (DPA) and N,N'-bis (2-aminoethyl) -1,2-ethanediamine dihydrochloride (Trien). Cuprimine is considered the primary treatment, although physicians are increasingly turning to Syprine as a first-line therapy. Both drugs exhibit oral systemic activity and low toxicity; their biological effects and safety are established. Previous in vivo studies using a rodent animal model established the decorporation potential of Cuprimine and Syprine for (60)Co and (210)Po. Currently these studies are being expanded to evaluate the in vivo decorporation efficacy of these drugs for several additional radionuclides. In this report, results of this investigation are discussed using the radionuclides (137)Cs, (60)Co, (192)Ir and (85)Sr. Short-term 48-h pilot studies were undertaken to evaluate DPA and Trien for their in vivo decorporation potential using male Wistar-Han rats. In these studies, a radionuclide solution was administered to the animals by intravenous (IV) injection, followed by a single IV dose of either DPA or Trien. Control animals received the radionuclide alone. Results show effective decorporation of (60)Co by DPA within the time frame evaluated. DPA and Trien were also modestly effective in decorporation of (137)Cs and (85)Sr, respectively. The study did not find DPA or Trien effective for decorporation of (192)Ir. Based on these encouraging findings, further studies to evaluate the dose-response profiles and timing of the chelator administration post exposure to radionuclides are warranted.

Characteristics of cesium accumulation in the filamentous soil bacterium Streptomyces sp. K202.

A filamentous soil bacterium, strain K202, was isolated from soil where an edible mushroom (Boletopsis leucomelas) was growing and identified as belonging to the genus Streptomyces on the basis of its morphological characteristics and the presence of LL-2, 6-diaminopimelic acid. We studied the existence states of Cs and its migration from extracellular to intracellular fluid in the mycelia of Streptomyces sp. K202. The results indicated that Cs accumulated in the cells through at least 2 steps: in the first step, Cs(+) was immediately and non-specifically adsorbed on the negatively charged cell surface, and in the second step, this adsorbed Cs(+) was taken up into the cytoplasm, and a part of the Cs entering the cytoplasm was taken up by an energy-dependent transport system(s). Further, we confirmed that a part of the Cs(+) was taken up into the mycelia competitively with K(+), because K(+) uptake into the intact mycelia of the strain was significantly inhibited by the presence of Cs(+) in the culture media. This suggested that part of the Cs is transported by the potassium transport system. Moreover, (133)Cs-NMR spectra and SEM-EDX spectra of the mycelia that accumulated Cs showed the presence of at least 2 intracellular Cs states: Cs(+) trapped by intercellular materials such as polyphosphate and Cs(+) present in a cytoplasmic pool.

Bioavailability of nanoscale metal oxides TiO(2), CeO(2), and ZnO to fish.

Nanoparticles (NPs) are reported to be a potential environmental health hazard. For organisms living in the aquatic environment, there is uncertainty on exposure because of a lack of understanding and data regarding the fate, behavior, and bioavailability of the nanomaterials in the water column. This paper reports on a series of integrative biological and physicochemical studies on the uptake of unmodified commercial nanoscale metal oxides, zinc oxide (ZnO), cerium dioxide (CeO(2)), and titanium dioxide (TiO(2)), from the water and diet to determine their potential ecotoxicological impacts on fish as a function of concentration. Particle characterizations were performed and tissue concentrations were measured by a wide range of analytical methods. Definitive uptake from the water column and localization of TiO(2) NPs in gills was demonstrated for the first time by use of coherent anti-Stokes Raman scattering (CARS) microscopy. Significant uptake of nanomaterials was found only for cerium in the liver of zebrafish exposed via the water and ionic titanium in the gut of trout exposed via the diet. For the aqueous exposures undertaken, formation of large NP aggregates (up to 3 mum) occurred and it is likely that this resulted in limited bioavailability of the unmodified metal oxide NPs in fish.

Development of functional I f channels in mMSCs after transfection with mHCN4: effects on cell morphology and mechanical activity in vitro.

OBJECTIVE: To study the functional properties of I(f) channels and the changes in mechanical activity of mouse mesenchymal stem cells (mMSCs) transfected with mHCN4. METHODS: mMSCs were purified by using CD11b-immunomagnetic microbeads and transfected with pMSCV-mHCN4-EGFP or pMSCV-EGFP. We examined the kinetic characteristics of the mHCN4 channel. The morphological changes of positively transfected mMSCs were investigated at the same time. RESULTS: The I(f) current recorded from the experimental group was sensitive to extracellular Cs(+) (-44.5 +/- 4.2 vs. -5.5 +/- 1.0 pA/pF, p < 0.001). The half-maximal activation was -99.0 +/- 5.8 mV. The time constant of activation was 451 +/- 61 ms under -140 mV. The control cells did not show the current under the same conditions. The absolute values of half-maximal activation decreased in the presence of cAMP or cGMP in the experimental group (-78.6 +/- 10.4 and -85.7 +/- 8.6 vs. -99.0 +/- 5.8 mV, respectively, p < 0.05). mMSCs transfected with pMSCV-mHCN4-EGFP could form spontaneous beating cells. Extracellular Cs(+) decreased the beating rate significantly (196 +/- 50 vs. 66 +/- 23 bmp, p < 0.01). CONCLUSIONS: Functional I(f) channels can be reconstructed in mMSCs infected with mHCN4. mMSCs modified by successful transfection with mHCN4 can differentiate so as to develop spontaneous mechanical activity.

Ingestion doses in Finland due to (90)Sr, (134)Cs, and (137)Cs from nuclear weapons testing and the Chernobyl accident.

(90)Sr and (137)Cs in domestic foodstuffs and water have been analysed in Finland since the early 1960s, and (134)Cs since 1986. Using data on radionuclide deposition levels, agricultural production, and the processing and consumption of foodstuffs, the average intake and radiation dose from the ingestion of these radionuclides have been assessed. The estimated committed effective dose from the ingestion of (90)Sr, (137)Cs, and (134)Cs in food and water for the period 1960-2005 is 2.2 mSv, and for the period since the Chernobyl accident in 1986 it is 1.3 mSv.

Diffusive transport within dentinal tubules: an X-ray microtomographic study.

The hydrodynamic theory of dentine hypersensitivity proposes that external stimuli cause dentinal fluid movement within dentinal tubules thereby triggering mechanosensitive nerves and eliciting a pain response. The aim of this study was to employ X-ray microtomography (XMT) to monitor diffusion of caesium acetate through dentine to investigate the extent to which transport occurs within the primary tubules compared to that through branched microtubules believed to run perpendicular to the direction of the primary dentinal tubules. 2.0-mm thick coronal dentine disks masked to leave half of the upper surface exposed were imaged by XMT, initially in water, which was then replaced with an aqueous solution of 0.50 mol l(-1) caesium acetate. Further XMT images were acquired after 1 and 6 days immersion. The XMT images were used to measure the change in the X-ray linear attenuation coefficient resulting from caesium acetate ingress into dentine. There was clearly considerable ingress of caesium acetate into the dentine lying below the exposed surface, but considerably less beneath the sealed surface, suggesting that diffusive transport occurs predominantly in the direction of the primary dentinal tubules, with no significant lateral transport. Primary tubules are clearly the dominant transmission route for triggering the mechanosensitive nerves present at the dentine-pulp interface, and for delivery of nerve desensitising agents.

A study of mechanisms responsible for incorporation of cesium and radiocesium into fruitbodies of king oyster mushroom (Pleurotus eryngii).

Ex vitro cultures of Pleurotus eryngii were carried out under controlled conditions using sterile medium composed of barley seeds. The influence of alkali and alkaline earth element salts (CsCl, KCl, NaCl, RbCl, and CaCl(2)) and tetraethylammonium chloride on incorporation of cesium, potassium, sodium, rubidium and calcium, and their distribution within fruitbodies, was examined. The results show that incorporation of cesium into fruitbodies was not suppressed by Na(+) and Rb(+) or tetraethylammonium chloride. However, it was inhibited by Ca(2+) and stimulated by high concentrations of K(+). The inhibition of cesium incorporation by Ca(2+), lack of influence of tetraethylammonium chloride and stimulation by high K(+) concentrations suggest that there may exist two pathways of passive transport of cesium in mycelium: (i) uptake mediated by a non-specific potassium channel localised in plasmalemma (similar to voltage-insensitive cation channel, VICC) followed by diffusive transport inside hyphae and (ii) extracellular transport from the medium through inter-hyphal cavities into fruitbodies. The results highlight distinctiveness of mechanisms responsible for the uptake and incorporation of cesium in mushrooms and plants.

The toxic function of cesium 5-sulfosalicylate based on the investigation of its trans-erythrocytes membrane behaviors and morphological properties.

In order to evaluate the cesium-induced toxic functional changes in organisms, transmembrane activities of cesium 5-sulfosalicylate (Cs(H(2)Ssal)) into human erythrocyte in vitro is presented in this paper, including kinetic characteristic of transport process and pathways involved in it. The uptake amount of Cs(H(2)Ssal) by erythrocyte was determined both by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) and spectrofluorimetry. The pathways of Cs(H(2)Ssal) transporting into erythrocyte are proposed according to inhibition investigation. The influence of Cs(H(2)Ssal) on morphological properties of erythrocytes was examined using Scanning Electron Microscopy (SEM) to determined the endurable concentration extent of erythrocytes to Cs(H(2)Ssal). Results show that transmembrane of Cs(H(2)Ssal) has characteristic of first-order kinetic process during the first 2h, and four pathways were involved in its transporting activities: Ca(2+) channel, Na(+)-K(+) pump, Na(+)-Cs(+) countertransport, and anion Cl(-)/CsCO(3)(-) exchange. The transmembrane process of Cs(H(2)Ssal) can both prevent the uptake of K(+) and induces abnormal accumulation of extracellular K(+) as well as occupy some K(+)-binding sites in protein, causing some tissues losing their activities and functions. Only high concentrations of Cs(H(2)Ssal) could change morphological properties of erythrocytes greatly and cause hemolysis eventually.

Metabolomic, proteomic and biophysical analyses of Arabidopsis thaliana cells exposed to a caesium stress. Influence of potassium supply.

The incorporation and localisation of 133Cs in a plant cellular model and the metabolic response induced were analysed as a function of external K concentration using a multidisciplinary approach. Sucrose-fed photosynthetic Arabidopsis thaliana suspension cells, grown in a K-containing or K-depleted medium, were submitted to a 1 mM Cs stress. Cell growth, strongly diminished in absence of K, was not influenced by Cs. In contrast, the chlorophyll content, affected by a Cs stress superposed to K depletion, did not vary under the sole K depletion. The uptake of Cs was monitored in vivo using 133Cs NMR spectroscopy while the final K and Cs concentrations were determined using atomic absorption spectrometry. Cs absorption rate and final concentration increased in a K-depleted external medium; in vivo NMR revealed that intracellular Cs was distributed in two kinds of compartment. Synchrotron X-ray fluorescence microscopy indicated that one could be the chloroplasts. In parallel, the cellular response to the Cs stress was analysed using proteomic and metabolic profiling. Proteins up- and down-regulated in response to Cs, in presence of K+ or not, were analysed by 2D gel electrophoresis and identified by mass spectrometry. No salient feature was detected excepting the overexpression of antioxidant enzymes, a common response of Arabidopsis cells stressed whether by Cs or by K-depletion. 13C and 31P NMR analysis of acid extracts showed that the metabolome impact of the Cs stress was also a function of the K nutrition. These analyses suggested that sugar metabolism and glycolytic fluxes were affected in a way depending upon the medium content in K+. Metabolic flux measurements using 13C labelling would be an elegant way to pursue on this line. Using our experimental system, a progressively stronger Cs stress might point out other specific responses elicited by Cs.

Comparison on plasma caesium kinetics in goats and horses with special emphasis on exercising horses.

AIMS: Like potassium (K+), caesium (Cs+) tends to concentrate intracellularly. The aim here was to determine how moderate exercise affects the uptake of Cs+ from blood plasma. METHODS: After an intravenous Cs+ dose of 5 micromol kg(-1), plasma Cs+ concentration was followed for 100 min in goats and for 60 min in horses. The latter were divided into two groups, one resting and the other trotting on a treadmill (inclination 3 degrees, speed 5 m s(-1)). RESULTS: The plasma Cs+ concentration follows a multiphase exponential decay curve, which initially could be approximated with a two-phase curve. The initially high rate constant (approximately 10 h(-1)) decreased to around 1 h(-1) in 40 min. Exercise more than doubled the rate of removal of Cs+ from plasma between 20 and 40 min after the start of exercise. After exercise, the rate returned to resting levels within 10 min. Plasma K+, on the contrary, declined for at least 20 min after exercise had ended. CONCLUSIONS: Moderate exercise significantly increases the rate of removal of Cs+ from the bloodstream. After exercise, the rate returns to the resting levels within 10 min. The increased rate of Cs+ removal during exercise is likely due to increased activity of Na+, K+-ATPase in working skeletal muscles.

Effect of K and bentonite additions on Cs-transfer to ryegrass.

Bentonite amendments are generally ineffective in reducing the soil-to-plant radiocaesium transfer but have previously been shown that bentonites in the K-form having been subjected to wetting-drying cycles had pronounced radiocaesium binding capacities. We have investigated the effect of wetting-drying (WD) on Radiocaesium Interception Potential (RIP) development in three K-bentonites and K-bentonite soil mixtures, using a variety of procedures: homogenisation of the bentonites with K through dialysis (K(B)), or partial transformation of the bentonite to the K-form in the presence of a solution of K2CO3 (K(L)) or in presence of solid K2CO3 (K(S)). Of the three strategies tested, addition of K2CO3 (solid) at a dose of 2 meq g(-1) clay and adding the K-bentonite mixtures to the soil resulted in the highest RIP increase after 20 WD cycles. The procedure giving the highest RIP yield is the most practical for further applications and was used in a pot experiment under greenhouse condition. When expressing the RIP increase of the soil-bentonite mixtures per unit bentonite added (RIP yield), 28- to 110-fold RIP increases were observed up to a value of approximately 60,000 meq kg(-1) (6 times higher than the RIP for illite). The beneficial effect following K-bentonite application was shown to be dependent both on a sorption enhancement effect (direct RIP effect) and fixation effects (indirect RIP effect). Greenhouse testing proved that the RIP effects observed in greenhouse could be predicted by making use of the sorption data from the laboratory tests. Optimum soil-amendment would be obtained with bentonites with high initial sorption RIP and a high sorption RIP increase when subjected to WD in the presence of potassium. Hypothised Transfer Factor (TF)-reductions of at least 10-fold could result when mixing approximately 1% bentonite, like Otay bentonite (RIP yield 99,000 meq kg(-1) after WD in presence of K if only fine particle size of <1mm considered) with the contaminated ploughing layer.

pH modulation using CsCl enhances therapeutic effects of vitamin D in LNCaP tumor bearing mice.

BACKGROUND: The downstream effects of pH modulation significantly impact the biological fate of chemotherapeutic agents and tumor responsiveness to therapy. We have studied the effects of cesium chloride (CsCl) on pH modulation and subsequent vitamin D treatment in vitamin D receptor (VDR) positive LNCaP tumors and VDR null MDA/LCC6 tumors in vivo. METHODS: Mice bearing LNCaP or MDA/LCC6 tumors were dosed orally with CsCl (150 mg/kg) or vitamin D (1 microg/kg) alone and in combination. Tumor volume and serum PSA (LNCaP only) were measured and intracellular pH was determined, using magnetic resonance spectroscopy (MRS), at tumor and leg muscle sites. Atomic absorption spectroscopy (AAS) was used to quantitate cesium in serum, organs, and tumor tissues. RESULTS: From day 10 onwards, statistically significant (P<0.01) differences were observed in all LNCaP treated groups as compared with control. CsCl co-administered with vitamin D, caused an apparent sensitization of efficacy in this tumor model. There were no correlating differences in serum PSA. Elevation of pH was statistically significant for all three treatment groups as compared with control. The pH measured in leg muscle was not influenced by CsCl treatment. Inhibition of tumor growth was not apparent in VDR null MDA/LCC6 tumors although intracellular tumor pH was shifted. Cesium was rapidly absorbed into serum and present in LNCaP tumors, prostates and other tissues after 1 hr, remaining for up to 24 hr. CONCLUSIONS: The data presented in this manuscript is the first report of chemosensitization by in vivo pH modulation using CsCl in mice bearing prostate or any other tumor xenograft.

Arbuscular mycorrhizal fungi mediated uptake of 137Cs in leek and ryegrass.

In a first experiment of soil contaminated with 137Cs, inoculation with a mixture of arbuscular mycorrhizae enhanced the uptake of 137Cs by leek under greenhouse conditions, while no effect on the uptake by ryegrass was observed. The mycorrhizal infection frequency in leek was independent of whether the 137Cs-contaminated soil was inoculated with mycorrhizal spores or not. The lack of mycorrhizae-mediated uptake of 137Cs in ryegrass could be due to the high root density, which was about four times that of leek, or due to a less well functioning mycorrhizal symbiosis than of leek. In a second experiment, ryegrass was grown for a period of four cuts. Additions of fungi enhanced 137Cs uptake of all harvests, improved dry weight production in the first cut, and also improved the mycorrhizal infection frequencies in the roots. No differences were obtained between the two fungal inoculums investigated with respect to biomass production or 137Cs uptake, but root colonization differed. We conclude that, under certain circumstances, mycorrhizae affect plant uptake of 137Cs. There may be a potential for selecting fungal strains that stimulate 137Cs accumulation in crops. The use of ryegrass seems to be rather ineffective for remediation of 137Cs-contaminated soil.