Directory of Open Access Journals (Sweden)
Lourdes Rubio
2018-05-01
Full Text Available Posidonia oceanica (L. Delile is a seagrass, the only group of vascular plants to colonize the marine environment. Seawater is an extreme yet stable environment characterized by high salinity, alkaline pH and low availability of essential nutrients, such as nitrate and phosphate. Classical depletion experiments, membrane potential and cytosolic sodium measurements were used to characterize the high-affinity NO3−, Pi and amino acids uptake mechanisms in this species. Net uptake rates of both NO3− and Pi were reduced by more than 70% in the absence of Na+. Micromolar concentrations of NO3− depolarized mesophyll leaf cells plasma membrane. Depolarizations showed saturation kinetics (Km = 8.7 ± 1 μM NO3−, which were not observed in the absence of Na+. NO3− induced depolarizations at increasing Na+ also showed saturation kinetics (Km = 7.2 ± 2 mM Na+. Cytosolic Na+ measured in P. oceanica leaf cells (17 ± 2 mM Na+ increased by 0.4 ± 0.2 mM Na+ upon the addition of 100 μM NO3−. Na+-dependence was also observed for high-affinity l-ala and l-cys uptake and high-affinity Pi transport. All together, these results strongly suggest that NO3−, amino acids and Pi uptake in P. oceanica leaf cells are mediated by high-affinity Na+-dependent transport systems. This mechanism seems to be a key step in the process of adaptation of seagrasses to the marine environment.
Diribe, C O; Warhurst, D C
1985-09-01
A study of concentration- and substrate-dependence of chloroquine uptake has been carried out on mouse erythrocytes infected with the chloroquine-sensitive NK65 and the chloroquine-resistant RC strains of Plasmodium berghei. The presence of drug binding sites of high and low affinity in such strains of P. berghei was confirmed. High affinity uptake sites in cells parasitized with chloroquine-sensitive and chloroquine-resistant parasites have similar characteristics, but in the sensitive strain the major component of chloroquine-uptake is at high affinity and dependent on the availability of ATP whilst in the resistant strain the major component of uptake is at low affinity and independent of energy. An absolute increase in the quantity of the low affinity site in erythrocytes parasitized with chloroquine-resistant P. berghei was noted, which may be related to an increase in quantity of parasite membrane.
High affinity, ligand specific uptake of complexed copper-67 by brain tissue incubated in vitro
International Nuclear Information System (INIS)
Barnea, A.; Hartter, D.E.
1987-01-01
Copper is an essential metal that is highly concentrated in the brain. The blood, the sole source of tissue Cu, contains 16-20 μM Cu, of which >95% is complexed to proteins and 2 was 10 times greater than that of CuAlbumin or Cu(II). Within the range of 0.2-150μM Cu, multiple uptake sites for CuHis were apparent. Increasing the molar ratio of His:Cu had a differential effect on Cu uptake: enhancing uptake at [Cu] 1 μM. Thus, using a His:Cu ratio of 1000, they observed a high affinity process exhibiting saturating and half saturating values of 5 μM and 1.5 μM Cu, respectively; using a His:Cu ratio of 2, they observed a low affinity process exhibiting saturating and half-saturating values of 100 μM and 40 μM Cu, respectively. Both processes required thermic but not metabolic energy, suggestive of facilitated diffusion. Considering the blood brain barrier for proteins, CuHis appears to be the major substrate for Cu uptake by neuronal tissue. They demonstrate the existence of a ligand specific, high affinity (apparent Km about 1.5 μM Cu) uptake process for CuHis in the brain, operative at the physiological concentration range of CuHis and histidine
Qi, Wenjing; Liu, Zhongyuan; Zhang, Wei; Halawa, Mohamed Ibrahim; Xu, Guobao
2016-01-01
Zr(IV) can form phosphate and Zr(IV) (?PO3 2??Zr4+?) complex owing to the high affinity between Zr(IV) with phosphate. Zr(IV) can induce the aggregation of gold nanoparticles (AuNPs), while adenosine triphosphate(ATP) can prevent Zr(IV)-induced aggregation of AuNPs. Herein, a visual and plasmon resonance absorption (PRA)sensor for ATP have been developed using AuNPs based on the high affinity between Zr(IV)with ATP. AuNPs get aggregated in the presence of certain concentrations of Zr(IV). Aft...
Lai, H; Carino, M A
1992-07-01
Acute (20 min) exposure to 100-dB white noise elicits a naltrexone-sensitive decrease in sodium-dependent high-affinity choline uptake in the frontal cortex and hippocampus of the rat. In the present study, the subtypes of opioid receptors involved were investigated by pretreating rats with microinjection of specific opioid-receptor antagonists into the lateral cerebroventricle before noise exposure. We found that the noise-induced decrease in high-affinity choline uptake in the hippocampus was blocked by pretreatment with either mu-, delta-, or kappa-opioid-receptor antagonists, whereas the effect of noise on frontal cortical high-affinity choline uptake was blocked by a mu- and delta- but not by a kappa-antagonist. These data further confirm the role of endogenous opioids in mediating the effects of noise on central cholinergic activity and indicate that different neural mechanisms are involved in the effects of noise on the frontal cortical and hippocampal cholinergic systems.
Kinetics and autoradiography of high affinity uptake of serotonin by primary astrocyte cultures
International Nuclear Information System (INIS)
Katz, D.M.; Kimelberg, H.K.
1985-01-01
Primary astrocyte cultures prepared from the cerebral cortices of neonatal rats showed significant accumulation of serotonin (5-hydroxytryptamine; [ 3 H]-5-HT). At concentrations in the range of 0.01 to 0.7 microM [ 3 H]-5-HT, this uptake was 50 to 85% Na+ dependent and gave a Km of 0.40 +/- 0.11 microM [ 3 H]-5-HT and a Vmax of 6.42 +/- 0.85 (+/- SEM) pmol of [ 3 H]-5-HT/mg of protein/4 min for the Na+-dependent component. In the absence of Na+ the uptake was nonsaturable. Omission of the monoamine oxidase inhibitor pargyline markedly reduced the Na+-dependent component of [ 3 H]-5-HT uptake but had a negligible effect on the Na+-independent component. This suggest significant oxidative deamination of serotonin after it has been taken up by the high affinity system, followed by release of its metabolite. The authors estimated that this system enabled the cells to concentrate [ 3 H]-5-HT up to 44-fold at an external [ 3 H]-5-HT concentration of 10(-7) M. Inhibition of [ 3 H]-5-HT uptake by a number of clinically effective antidepressants was also consistent with a specific high affinity uptake mechanism for 5-HT, the order of effectiveness of inhibition being chlorimipramine greater than fluoxetine greater than imipramine = amitriptyline greater than desmethylimipramine greater than iprindole greater than mianserin. Uptake of [ 3 H]-5-HT was dependent on the presence of Cl- as well as Na+ in the medium, and the effect of omission of both ions was nonadditive. Varying the concentration of K+ in the media from 1 to 50 mM had a limited effect on [ 3 H]-5-HT uptake
DEFF Research Database (Denmark)
Jørgensen, Thomas R; vanKuyk, Patricia A; Poulsen, Bjarne R
2007-01-01
This is a study of high-affinity glucose uptake in Aspergillus niger and the effect of disruption of a high-affinity monosaccharide-transporter gene, mstA. The substrate saturation constant (K(s)) of a reference strain was about 15 microM in glucose-limited chemostat culture. Disruption of mst......-affinity uptake system of A. niger. The mstA disruptant and a reference strain were cultivated in glucose-limited chemostat cultures at low, intermediate and high dilution rate (D=0.07 h(-1), 0.14 h(-1) and 0.20 h(-1)). Mycelium harvested from steady-state cultures was subjected to glucose uptake assays...
Energy Technology Data Exchange (ETDEWEB)
Metcalf, R.H.; Boegman, R.J.; Quirion, R.; Riopelle, R.J.; Ludwin, S.K.
1987-08-01
A transient 45% increase in cortical high-affinity choline uptake (HACU) was observed after an injection of quinolinic acid (QUIN) into the nucleus basalis magnocellularis (nbM) of the rat. This was followed by a steady decline in choline uptake, which resulted in a 46% decrease by day 7. Specific (/sup 3/H)hemicholinium-3 binding to coronal brain sections showed a similar pattern following injections of QUIN into the nbM. The increase in cortical HACU elicited by QUIN appeared to be dose dependent.
Carbonate-sensitive phytotransferrin controls high-affinity iron uptake in diatoms
McQuaid, Jeffrey B.; Kustka, Adam B.; Oborník, Miroslav; Horák, Aleš; McCrow, John P.; Karas, Bogumil J.; Zheng, Hong; Kindeberg, Theodor; Andersson, Andreas J.; Barbeau, Katherine A.; Allen, Andrew E.
2018-03-01
In vast areas of the ocean, the scarcity of iron controls the growth and productivity of phytoplankton. Although most dissolved iron in the marine environment is complexed with organic molecules, picomolar amounts of labile inorganic iron species (labile iron) are maintained within the euphotic zone and serve as an important source of iron for eukaryotic phytoplankton and particularly for diatoms. Genome-enabled studies of labile iron utilization by diatoms have previously revealed novel iron-responsive transcripts, including the ferric iron-concentrating protein ISIP2A, but the mechanism behind the acquisition of picomolar labile iron remains unknown. Here we show that ISIP2A is a phytotransferrin that independently and convergently evolved carbonate ion-coordinated ferric iron binding. Deletion of ISIP2A disrupts high-affinity iron uptake in the diatom Phaeodactylum tricornutum, and uptake is restored by complementation with human transferrin. ISIP2A is internalized by endocytosis, and manipulation of the seawater carbonic acid system reveals a second-order dependence on the concentrations of labile iron and carbonate ions. In P. tricornutum, the synergistic interaction of labile iron and carbonate ions occurs at environmentally relevant concentrations, revealing that carbonate availability co-limits iron uptake. Phytotransferrin sequences have a broad taxonomic distribution and are abundant in marine environmental genomic datasets, suggesting that acidification-driven declines in the concentration of seawater carbonate ions will have a negative effect on this globally important eukaryotic iron acquisition mechanism.
Inhibition of high affinity choline uptake by N-allyl-3-quinuclidinol
International Nuclear Information System (INIS)
Asermely, K.E.; O'Neill, J.J.
1986-01-01
The peripheral actions of N-allyl-3-quinuclidinol (N-Al-3-OHQ) on high affinity choline uptake (HAChU) on rat phrenic nerve diaphragm are described. Endplate regions (EPA) identified by the Koelle histochemical techniques for acetylcholinesterase, were dissected from adult rat hemidiaphragms and placed in cold Krebs solution (pH-7.35). All measurements of HAChU were at 37 0 C in buffers containing tritium choline (5 μM 0.124 μC/mmole) at intervals of 1, 2, 4, 8, 15 and 30 min. Tissues were washed 3x, digested in 1N NaOH and counted for tritium in Chaikoff's solution. All data are expressed as pmole Ch/g wet weight. Comparison between EPA and non-EPA tissue demonstrate HAChU and slow choline diffusion, respectively. Steady state is observed in 15 min. N-Al-3-OHQ produces 15% inhibition at 5 x 10 -5 M compared with 50% inhibition on brain synaptosomes. At 5 x 10 -4 M N-Al-3-OHQ, 30% inhibition is observed. Attempts to deplete ACh by pre-stimulation with high K + -ion (25 mM) were unsuccessful; tissue 3 H-choline uptake appeared to oscillate over a 30 min period
Inhibition of high affinity choline uptake by N-allyl-3-quinuclidinol
Energy Technology Data Exchange (ETDEWEB)
Asermely, K.E.; O' Neill, J.J.
1986-03-01
The peripheral actions of N-allyl-3-quinuclidinol (N-Al-3-OHQ) on high affinity choline uptake (HAChU) on rat phrenic nerve diaphragm are described. Endplate regions (EPA) identified by the Koelle histochemical techniques for acetylcholinesterase, were dissected from adult rat hemidiaphragms and placed in cold Krebs solution (pH-7.35). All measurements of HAChU were at 37/sup 0/C in buffers containing tritium choline (5 ..mu..M 0.124 ..mu..C/mmole) at intervals of 1, 2, 4, 8, 15 and 30 min. Tissues were washed 3x, digested in 1N NaOH and counted for tritium in Chaikoff's solution. All data are expressed as pmole Ch/g wet weight. Comparison between EPA and non-EPA tissue demonstrate HAChU and slow choline diffusion, respectively. Steady state is observed in 15 min. N-Al-3-OHQ produces 15% inhibition at 5 x 10/sup -5/ M compared with 50% inhibition on brain synaptosomes. At 5 x 10/sup -4/ M N-Al-3-OHQ, 30% inhibition is observed. Attempts to deplete ACh by pre-stimulation with high K/sup +/-ion (25 mM) were unsuccessful; tissue /sup 3/H-choline uptake appeared to oscillate over a 30 min period.
Energy Technology Data Exchange (ETDEWEB)
Rana, B C; Kumar, H D
1974-01-01
Certain algae isolated from polluted and nonpolluted habitats were studied for their capacity to absorb copper, zinc, and phosphate from the ambient medium. They were found to possess a high gleaning capacity for these pollutants. The uptake of copper does not seem to require much metabolic energy and is independent of the growth of the alga, but the uptake of zinc seems to depend directly on its growth. Anacystis nidulans and Chlorella vulgaris are fast growing algae; they can absorb high amounts of phosphate and can be gainfully employed for retrieving the phosphate from the medium. However, the algae must be harvested before they excrete some of the phosphates back into the medium.
International Nuclear Information System (INIS)
Zhang, Xinxin; Zhang, Min; Takano, Tetsuo; Liu, Shenkui
2011-01-01
Highlights: → The AtCCX5 protein coding a putative cation calcium exchanger was characterized. → AtCCX5 expressed in yeast was localized in the plasma membrane and nuclear periphery. → AtCCX5 protein did not show the same transport properties as the CAXs. → AtCCX5 protein involves in mediating high-affinity K + uptake in yeast. → AtCCX5 protein also involves in Na + transport in yeast. -- Abstract: The gene for a putative cation calcium exchanger (CCX) from Arabidopsis thaliana, AtCCX5, was cloned and its function was analyzed in yeast. Green fluorescent protein-tagged AtCCX5 expressed in yeast was localized in the plasma membrane and nuclear periphery. The yeast transformants expressing AtCCX5 were created and their growth in the presence of various cations (K + , Na + , Ca 2+ , Mg 2+ , Fe 2+ , Cu 2+ , Co 2+ , Cd 2+ , Mn 2+ , Ba 2+ , Ni 2+ , Zn 2+ , and Li + ) were analyzed. AtCCX5 expression was found to affect the response to K + and Na + in yeast. The AtCCX5 transformant also showed a little better growth to Zn 2+ . The yeast mutant 9.3 expressing AtCCX5 restored growth of the mutant on medium with low K + (0.5 mM), and also suppressed its Na + sensitivity. Ion uptake experiments showed that AtCCX5 mediated relatively high-affinity K + uptake and was also involved in Na + transport in yeast. Taken together, these findings suggest that the AtCCX5 is a novel transport protein involves in mediating high-affinity K + uptake and Na + transport in yeast.
International Nuclear Information System (INIS)
Bole, J.B.
1986-01-01
The availability of nitrogen and phosphorus in fertilizer products labelled with both 32 P and 15 N was measured in a growth chamber experiment. The uptake of N and P by soft white spring wheat (Triticum aestivum L.) from a solution of acid urea phosphate fertilizer did not differ significantly from that of a mixture of granular urea and monammonium phosphate fertilizer. The fertilizer-P uptake efficiency of both sources was higher in a neutral soil than in acid or calcareous soils. Banding either fertilizer increased the uptake of fertilizer P compared with sources mixed with the soil, but did not significantly affect fertilizer-N uptake. The increase in fertilizer-P efficiency due to banding was significantly greater for the urea-monammonium phosphate than for the acid urea phosphate solution. Banding fertilizer did not increase the uptake of fertilizer P in the calcareous soil, and decreased the uptake of fertilizer N in that soil compared with mixed treatments. It is suggested that soluble Ca formed from the reaction of acid with naturally occurring lime may have reduced the availability of fertilizer P in the band
Qi, Wenjing; Liu, Zhongyuan; Zhang, Wei; Halawa, Mohamed Ibrahim; Xu, Guobao
2016-10-12
Zr(IV) can form phosphate and Zr(IV) (-PO₃ 2- -Zr 4+ -) complex owing to the high affinity between Zr(IV) with phosphate. Zr(IV) can induce the aggregation of gold nanoparticles (AuNPs), while adenosine triphosphate(ATP) can prevent Zr(IV)-induced aggregation of AuNPs. Herein, a visual and plasmon resonance absorption (PRA)sensor for ATP have been developed using AuNPs based on the high affinity between Zr(IV)with ATP. AuNPs get aggregated in the presence of certain concentrations of Zr(IV). After the addition of ATP, ATP reacts with Zr(IV) and prevents AuNPs from aggregation, enabling the detection of ATP. Because of the fast interaction of ATP with Zr(IV), ATP can be detected with a detection limit of 0.5 μM within 2 min by the naked eye. Moreover, ATP can be detected by the PRA technique with higher sensitivity. The A 520nm / A 650nm values in PRA spectra increase linearly with the concentrations of ATP from 0.1 μM to 15 μM (r = 0.9945) with a detection limit of 28 nM. The proposed visual and PRA sensor exhibit good selectivity against adenosine, adenosine monophosphate, guanosine triphosphate, cytidine triphosphate and uridine triphosphate. The recoveries for the analysis of ATP in synthetic samples range from 95.3% to 102.0%. Therefore, the proposed novel sensor for ATP is promising for real-time or on-site detection of ATP.
Grillo-Puertas, Mariana; Schurig-Briccio, Lici Ariane; Rodríguez-Montelongo, Luisa; Rintoul, María Regina; Rapisarda, Viviana Andrea
2014-01-01
Background Metal tolerance in bacteria has been related to polyP in a model in which heavy metals stimulate the polymer hydrolysis, forming metal-phosphate complexes that are exported. As previously described in our laboratory, Escherichia coli cells grown in media containing a phosphate concentration >37 mM maintained an unusually high polyphosphate (polyP) level in stationary phase. The aim of the present work was to evaluate the influence of polyP levels as the involvement of low-affinity ...
Directory of Open Access Journals (Sweden)
Wenjing Qi
2016-10-01
Full Text Available Zr(IV can form phosphate and Zr(IV (–PO32−–Zr4+– complex owing to the high affinity between Zr(IV with phosphate. Zr(IV can induce the aggregation of gold nanoparticles (AuNPs, while adenosine triphosphate(ATP can prevent Zr(IV-induced aggregation of AuNPs. Herein, a visual and plasmon resonance absorption (PRAsensor for ATP have been developed using AuNPs based on the high affinity between Zr(IVwith ATP. AuNPs get aggregated in the presence of certain concentrations of Zr(IV. After the addition of ATP, ATP reacts with Zr(IV and prevents AuNPs from aggregation, enabling the detection of ATP. Because of the fast interaction of ATP with Zr(IV, ATP can be detected with a detection limit of 0.5 μM within 2 min by the naked eye. Moreover, ATP can be detected by the PRA technique with higher sensitivity. The A520nm/A650nm values in PRA spectra increase linearly with the concentrations of ATP from 0.1 μM to 15 μM (r = 0.9945 with a detection limit of 28 nM. The proposed visual and PRA sensor exhibit good selectivity against adenosine, adenosine monophosphate, guanosine triphosphate, cytidine triphosphate and uridine triphosphate. The recoveries for the analysis of ATP in synthetic samples range from 95.3% to 102.0%. Therefore, the proposed novel sensor for ATP is promising for real-time or on-site detection of ATP.
Grillo-Puertas, Mariana; Schurig-Briccio, Lici Ariane; Rodríguez-Montelongo, Luisa; Rintoul, María Regina; Rapisarda, Viviana Andrea
2014-03-19
Metal tolerance in bacteria has been related to polyP in a model in which heavy metals stimulate the polymer hydrolysis, forming metal-phosphate complexes that are exported. As previously described in our laboratory, Escherichia coli cells grown in media containing a phosphate concentration >37 mM maintained an unusually high polyphosphate (polyP) level in stationary phase. The aim of the present work was to evaluate the influence of polyP levels as the involvement of low-affinity inorganic phosphate transport (Pit) system in E. coli copper tolerance. PolyP levels were modulated by the media phosphate concentration and/or using mutants in polyP metabolism. Stationary phase wild-type cells grown in high phosphate medium were significantly more tolerant to copper than those grown in sufficient phosphate medium. Copper addition to tolerant cells induced polyP degradation by PPX (an exopolyphosphatase), phosphate efflux and membrane polarization. ppk-ppx- (unable to synthesize/degrade polyP), ppx- (unable to degrade polyP) and Pit system mutants were highly sensitive to metal even in high phosphate media. In exponential phase, CopA and polyP-Pit system would act simultaneously to detoxify the metal or one could be sufficient to safeguard the absence of the other. Our results support a mechanism for copper detoxification in exponential and stationary phases of E. coli, involving Pit system and degradation of polyP. Data reflect the importance of the environmental phosphate concentration in the regulation of the microbial physiological state.
DEFF Research Database (Denmark)
Christiansen, Nina Høj; Andersen, Frede Østergaard; Jensen, Henning S.
2016-01-01
Phosphate (Pi) uptake kinetics were determined in shoot and root tissues for four freshwater macrophyte species, Littorella uniflora, Potamogeton perfoliatus, Myriophyllum alterniflorum and Elodea canadensis, using a radioactive 33P phosphate technique. Collection of plant material in the oligotr...
International Nuclear Information System (INIS)
Robitaille, Y.; Sherwin, A.
1984-01-01
Cortical astrocytes of normal mammalian brain are endowed with a high affinity uptake system for β-Alanine which is competitively inhibited by gamma aminobutyric acid (GABA), a neurotransmitter strongly implicated in epileptogenesis. The authors evaluated ( 3 H) β-Alanine uptake by reactive astrocytes proliferating within scar of epileptogenic foci induced in rat motor cortex by microinjections of 100 mM ferric chloride. Following in vitro incubation of scar tissue with ( 3 H) β-Alanine, ultrastructural morphometry of grain patterns at 5, 30 and 120 days post injection revealed early and significant grain count increases over astroglial processes, predominantly those related to perivascular glial end-feet. Astrocytic cell body and endothelial cell counts showed a more gradual and stepwise increase. Similar data were obtained by comparing visual and edited mean astrocytic grain counts. These results suggest that the enhanced uptake of reactive astrocytes may reflect a marked decrease of inhibitory GABAergic neurons within ferric chloride-induced scars. 7 figures, 1 table
Inorganic phosphate uptake in unicellular eukaryotes.
Dick, Claudia F; Dos-Santos, André L A; Meyer-Fernandes, José R
2014-07-01
Inorganic phosphate (Pi) is an essential nutrient for all organisms. The route of Pi utilization begins with Pi transport across the plasma membrane. Here, we analyzed the gene sequences and compared the biochemical profiles, including kinetic and modulator parameters, of Pi transporters in unicellular eukaryotes. The objective of this review is to evaluate the recent findings regarding Pi uptake mechanisms in microorganisms, such as the fungi Neurospora crassa and Saccharomyces cerevisiae and the parasite protozoans Trypanosoma cruzi, Trypanosoma rangeli, Leishmania infantum and Plasmodium falciparum. Pi uptake is the key step of Pi homeostasis and in the subsequent signaling event in eukaryotic microorganisms. Biochemical and structural studies are important for clarifying mechanisms of Pi homeostasis, as well as Pi sensor and downstream pathways, and raise possibilities for future studies in this field. Copyright © 2014 Elsevier B.V. All rights reserved.
Krueger, R D; Harper, S H; Campbell, J W; Fahrney, D E
1986-07-01
The archaebacterium Methanobacterium thermoautotrophicum was grown in continuous culture at 65 degrees C in a phosphate-limited medium at specific growth rates from 0.06 to 0.28 h-1 (maximum growth rate [mu max] = 0.36 h-1). Cyclic-2,3-diphosphoglycerate (cyclic DPG) levels ranged from 2 to 20 mM in Pi-limited cells, compared with about 30 mM in batch-grown cells. The Monod constant for Pi-limited growth was 5 nM. Pi uptake rates were determined by following the disappearance of 32Pi from the medium. Interrupting the H2 supply stopped the uptake of Pi and the release of organic phosphates. Little or no efflux of Pi occurred in the presence or absence of H2. Pi uptake of cells adapted to nanomolar Pi concentrations could be accounted for by the operation of one uptake system with an apparent Km of about 25 nM and a Vmax of 58 nmol of Pi per min per g (dry weight). Uptake curves at 30 microM Pi or above were biphasic due to a sevenfold decrease in Vmax after an initial phase of rapid movement of Pi into the cell. Under these conditions the growth rate slowed to zero and the cyclic DPG pool expanded before growth resumed. Thus, three properties of M. thermoautotrophicum make it well adapted to live in a low-P environment: the presence of a low-Km, high-Vmax uptake system for Pi; the ability to accumulate cyclic DPG rapidly; and a growth strategy in which accumulation of Pi and cyclic DPG takes precedence over a shift-up in growth rate when excess Pi becomes available.
Krueger, R D; Harper, S H; Campbell, J W; Fahrney, D E
1986-01-01
The archaebacterium Methanobacterium thermoautotrophicum was grown in continuous culture at 65 degrees C in a phosphate-limited medium at specific growth rates from 0.06 to 0.28 h-1 (maximum growth rate [mu max] = 0.36 h-1). Cyclic-2,3-diphosphoglycerate (cyclic DPG) levels ranged from 2 to 20 mM in Pi-limited cells, compared with about 30 mM in batch-grown cells. The Monod constant for Pi-limited growth was 5 nM. Pi uptake rates were determined by following the disappearance of 32Pi from the medium. Interrupting the H2 supply stopped the uptake of Pi and the release of organic phosphates. Little or no efflux of Pi occurred in the presence or absence of H2. Pi uptake of cells adapted to nanomolar Pi concentrations could be accounted for by the operation of one uptake system with an apparent Km of about 25 nM and a Vmax of 58 nmol of Pi per min per g (dry weight). Uptake curves at 30 microM Pi or above were biphasic due to a sevenfold decrease in Vmax after an initial phase of rapid movement of Pi into the cell. Under these conditions the growth rate slowed to zero and the cyclic DPG pool expanded before growth resumed. Thus, three properties of M. thermoautotrophicum make it well adapted to live in a low-P environment: the presence of a low-Km, high-Vmax uptake system for Pi; the ability to accumulate cyclic DPG rapidly; and a growth strategy in which accumulation of Pi and cyclic DPG takes precedence over a shift-up in growth rate when excess Pi becomes available. PMID:3722128
Miller, J. A.; Richter, J. A.
1985-01-01
The effects of several anticonvulsant drugs on sodium-dependent high affinity choline uptake (HACU) in mouse hippocampal synaptosomes was investigated. HACU was measured in vitro after in vivo administration of the drug to mice. HACU was inhibited by drugs which have in common the ability to facilitate gamma-aminobutyric acid (GABA) transmission, pentobarbitone, phenobarbitone, barbitone, diazepam, chloridiazepoxide, and valproic acid. Dose-response relationships were determined for these drugs and the drugs' potencies at inhibiting HACU correlated well with their anticonvulsant potencies. Clonazepam, ethosuximide, carbamazepine, and barbituric acid had no effect on HACU in the doses used while phenytoin and trimethadione stimulated HACU. These results suggest that certain anticonvulsants may elicit a part of their anticonvulsant activity by modulating cholinergic neurones. This effect may be mediated through a GABA mechanism. PMID:3978310
Leelawattanachai, Jeerapond; Kwon, Keon-Woo; Michael, Praveesuda; Ting, Richard; Kim, Ju-Young; Jin, Moonsoo M.
2015-01-01
The ability to use a systemically injected agent to image tumor is influenced by tumor characteristics such as permeability and vascularity, and the size, shape, and affinity of the imaging agent. In this study, six different imaging biomolecules, with or without specificity to tumor, were examined for tumor uptake and internalization at the whole body, ex-vivo tissue, and cellular levels: antibodies, antibody fragments (Fab), serum albumin, and streptavidin. The time of peak tumor uptake was dependent solely on the size of molecules, suggesting that molecular size is the major factor that influences tumor uptake by its effect on systemic clearance and diffusion into tumor. Affinity to tumor antigen failed to augment tumor uptake of Fab above non-specific accumulation, which suggests that Fab fragments of typical monoclonal antibodies may fall below an affinity threshold for use as molecular imaging agents. Despite abundant localization into the tumor, albumin and streptavidin were not found on cell surface or inside cells. By comparing biomolecules differing in size and affinity, our study highlights that while pharmacokinetics are a dominant factor in tumor uptake for biomolecules, affinity to tumor antigen is required for tumor binding and internalization. PMID:25901755
International Nuclear Information System (INIS)
Haberly, L.B.; Hansen, D.J.; Feig, S.L.; Presto, S.
1987-01-01
GABAergic neurons have been identified in the piriform cortex of the opossum at light and electron microscopic levels by immunocytochemical localization of GABA and the GABA-synthesizing enzyme glutamic acid decarboxylase and by autoradiographic visualization of high-affinity 3 H-GABA uptake. Four major neuron populations have been distinguished on the basis of soma size, shape, and segregation at specific depths and locations: large horizontal cells in layer Ia of the anterior piriform cortex, small globular cells with thin dendrites concentrated in layers Ib and II of the posterior piriform cortex, and multipolar and fusiform cells concentrated in the deep part of layer III in anterior and posterior parts of the piriform cortex and the subjacent endopiriform nucleus. All four populations were well visualized with both antisera, but the large layer Ia horizontal cells displayed only very light 3 H-GABA uptake, thus suggesting a lack of local axon collaterals or lack of high-affinity GABA uptake sites. The large, ultrastructurally distinctive somata of layer Ia horizontal cells receive a very small number of symmetrical synapses; the thin, axonlike dendrites of small globular cells are exclusively postsynaptic and receive large numbers of both symmetrical and asymmetrical synapses, in contrast to somata which receive a small number of both types; and the deep multipolar and fusiform cells receive a highly variable number of symmetrical and asymmetrical synapses on somata and proximal dendrites. Labeled puncta of axon terminal dimensions were found in large numbers in the neuropil surrounding pyramidal cell somata in layer II and in the endopiriform nucleus. Moderately large numbers of labeled puncta were found in layer I at the depth of pyramidal cell apical dendrites with greater numbers in layer Ia at the depth of distal apical segments than in layer Ib
Hartmann, Manuela; Grob, Carolina; Scanlan, David J; Martin, Adrian P; Burkill, Peter H; Zubkov, Mikhail V
2011-11-01
The smallest phototrophic protists (protists meet their inorganic nutrient requirements, we compared the phosphate uptake rates of plastidic and aplastidic protists in the phosphate-depleted subtropical and tropical North Atlantic (4-29°N) using a combination of radiotracers and flow cytometric sorting on two Atlantic Meridional Transect cruises. Plastidic protists were divided into two groups according to their size (protists showed higher phosphate uptake rates per cell than the aplastidic protists. Although the phosphate uptake rates of protist cells were on average seven times (Pprotists were one fourth to one twentieth of an average bacterioplankton cell. The unsustainably low biomass-specific phosphate uptake by both plastidic and aplastidic protists suggests the existence of a common alternative means of phosphorus acquisition - predation on phosphorus-rich bacterioplankton cells. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Phosphate uptake and growth characteristics of transgenic rice with ...
African Journals Online (AJOL)
Yomi
2012-04-03
Apr 3, 2012 ... In this study, we investigated phosphate uptake pat- terns and growth ... at 50°C OsPT1 and actin amplication, second strand cDNA synthesis for 2 min at .... weight of the stem in wild-type plants increased signifi- cantly under ...
International Nuclear Information System (INIS)
Burkholder, J.M.; Wetzel, R.G.; Klomparens, K.L.
1990-01-01
We report a direct comparison of phosphate uptake by adnate and loosely attached microalgae in an intact biofilm matrix, with resolution at the level of individual cells. Track scanning electron microscope autoradiography enabled assay of [ 33 P]phosphate uptake from the overlying water by adnate algae left undisturbed on mature leaves of the macrophyte Potamogeton illinoensis or on artificial plant mimics. The epiphyte communities developed in either phosphate-poor or moderately phosphate-enriched water, and they were assayed on both natural and artificial plants. All adnate taxa examined from both natural and artificial plants in both habitats took up significantly less radiolabel when assayed beneath the overlying matrix than when they were exposed to the water upon removal of the overstory material. Track scanning electron microscope autoradiography and track light microscope autoradiography were intercalibrated to enable comparison of [ 33 P]phosphate uptake by adnate and loosely attached components of the epiphyte matrix. Loosley attached cells on substrata from both habitats took up significantly more radiolabel than did underlying adnate cells, indicating that access to phosphate supplies from the water depended on the position of microbial cells in the matrix. In this short-term assay, the adnate microalgae were relatively isolated from the water column nutrient source
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Sugiyanto Sugiyanto
2008-07-01
Full Text Available Effort repair of land quality better be done by simultan namely with application of organic matters and inorganic fertilization. The objective of this research is to study the effect of varied organic matters source and phosphate fertilizers on the chemicals soil characteristic and cocoa nutrient uptake. The experiment was laid experimentally in split-plot design and environmentally in randomized complete block design. The main plot was source of P consisted of, control, SP 36 and rock phosphate in dosage of 200 mg P2O5 per kg of air dry soil. Source of organic matter as sub-plot consisted of control (no organic matter, cow dung, cocoa pod husk compost and sugar cane filter cake, each in dosage of 2.5 and 5.0%. Result of this experiment showed application of cow dung, cocoa pod husk compost and sugar cane filter cake increased content of C, N, Ca exchangeable, Fe available, and pH in soil, and SP 36 increased availability of P in soil. Application of sugar cane filter cake increased N, K, Ca, Mg, and SO4 uptake but did not increase Cl uptake, application of cow dung in dosage 5% increased N, K, and Cl uptake and cocoa pod husk compost dosage 5% increased N and K uptake of cocoa. SP 36 increased Mg uptake of cocoa but rock phosphate did not increase it. They were not interaction between organic matters and phosphate fertilizers to nutrient uptake of cocoa. Nutrient soil content as affected by organic matters correlated with nutrient uptake of cocoa.Key words : soil chemical properties, nutrient uptake, cocoa, organic matter, phosphate fertlizers.
Tatry, Marie-Violaine; El Kassis, Elie; Lambilliotte, Raphaël; Corratgé, Claire; van Aarle, Ingrid; Amenc, Laurie K; Alary, Rémi; Zimmermann, Sabine; Sentenac, Hervé; Plassard, Claude
2009-03-01
Ectomycorrhizal symbiosis markedly improves plant phosphate uptake, but the molecular mechanisms underlying this benefit are still poorly understood. We identified two ESTs in a cDNA library prepared from the ectomycorrhizal basidiomycete Hebeloma cylindrosporum with significant similarities to phosphate transporters from the endomycorrhizal fungus Glomus versiforme and from non-mycorrhizal fungi. The full-length cDNAs corresponding to these two ESTs complemented a yeast phosphate transport mutant (Deltapho84). Measurements of (33)P-phosphate influx into yeast expressing either cDNA demonstrated that the encoded proteins, named HcPT1 and HcPT2, were able to mediate Pi:H(+) symport with different affinities for Pi (K(m) values of 55 and 4 mum, respectively). Real-time RT-PCR showed that Pi starvation increased the levels of HcPT1 transcripts in H. cylindrosporum hyphae grown in pure culture. Transcript levels of HcPT2 were less dependent on Pi availability. The two transporters were expressed in H. cylindrosporum associated with its natural host plant, Pinus pinaster, grown under low or high P conditions. The presence of ectomycorrhizae increased net Pi uptake rates into intact Pinus pinaster roots at low or high soil P levels. The expression patterns of HcPT1 and HcPT2 indicate that the two fungal phosphate transporters may be involved in uptake of phosphate from the soil solution under the two soil P availability conditions used.
Proadifen-sensitive high affinity binding of 3H-alaproclate to liver membranes
International Nuclear Information System (INIS)
Ross, S.B.
1987-01-01
3 H-alaproclate, a selective 5 h ydroxytryptamine uptake inhibitor, was found to bind to microsomal membranes from the rat liver with high affinity (K D -=3 nM) and large capacity (B max about 2 nmol/g liver). This binding was stereoselective since S-( - )-alaproclate was 30 times more potent than the R-( + )-enantiomer to displace the 3 H-labelled racemate. Proadifen (SKF 525A), an inhibitor of cytochrome P-450, displaced the 3 H-alaproclate binding with the same, high affinity (K i =3 nM) as alaproclate itself. Repeated treatment with phenobarbital sodium (5x75 mg/kg intraperitoneally) increased the number of alaproclate binding sites 7-8 times without changing the affinity. However, most of the phenobarbital induced 3 H-alaproclate binding was not displaceable by proadifen, showing the presence of at least two different high affinity binding sites. The possible involvement of cytochrome P-450 in the alaproclate binding is discussed. (author)
International Nuclear Information System (INIS)
Cao Xinde; Ma, Lena Q.; Shiralipour, Aziz
2003-01-01
Chinese brake fern (Pteris vittata L.), an arsenic (As) hyperaccumulator, has shown the potential to remediate As-contaminated soils. This study investigated the effects of soil amendments on the leachability of As from soils and As uptake by Chinese brake fern. The ferns were grown for 12 weeks in a chromated-copper-arsenate (CCA) contaminated soil or in As spiked contaminated (ASC) soil. Soils were treated with phosphate rock, municipal solid waste, or biosolid compost. Phosphate amendments significantly enhanced plant As uptake from the two tested soils with frond As concentrations increasing up to 265% relative to the control. After 12 weeks, plants grown in phosphate-amended soil removed >8% of soil As. Replacement of As by P from the soil binding sites was responsible for the enhanced mobility of As and subsequent increased plant uptake. Compost additions facilitated As uptake from the CCA soil, but decreased As uptake from the ASC soil. Elevated As uptake in the compost-treated CCA soil was related to the increase of soil water-soluble As and As(V) transformation into As(III). Reduced As uptake in the ASC soil may be attributed to As adsorption to the compost. Chinese brake fern took up As mainly from the iron-bound fraction in the CCA soil and from the water-soluble/exchangeable As in the ASC soil. Without ferns for As adsorption, compost and phosphate amendments increased As leaching from the CCA soil, but had decreased leaching with ferns when compared to the control. For the ASC soil, treatments reduced As leaching regardless of fern presence. This study suggest that growing Chinese brake fern in conjunction with phosphate amendments increases the effectiveness of remediating As-contaminated soils, by increasing As uptake and decreasing As leaching. - Phosphate amendment increases the effectiveness of Chinese brake fern to remediate As-contaminated soils, by increasing As uptake and decreasing As leaching
Ma, Juan; Li, Lu; Yu, Xiao-jun; Sun, Lei-jun; Sun, Hong-wei; Chen, Yong-zhi
2015-10-01
An alternating anaerobic/oxic ( An/O) sequencing batch reactor (SBR) was employed to investigate the long-term inhibitory effect of free nitrous acid (FNA) on aerobic phosphorus uptake performance and variation of phosphorus uptake properties of the sludge by adding nitrite. The reactor was started up under the condition of 21-23 degrees C. The results showed that FNA had no impact on phosphate release and uptake capacities of the sludge. However, the specific phosphate release/uptake rates was found to be higher. As FNA concentration (measure by HNO2-N) was lower than 0.53 x 10(-3) mg x L(-1), phosphorus removal efficiency of the system was higher than 96.9%. When the FNA concentration was increased to 0.99 x 10(-3) mg x L(-1), 1.46 x 10(-3) mg x L(-1) and 1.94 x 10(-3) mg x L(-1), the phosphorus removal performance deteriorated rapidly. The phosphorus removal efficiency was recovered to 64.42%, 67.33% and 44.14% after 50, 12 and 30 days, respectively, which implied the deterioration of phosphorus removal performance caused by FNA inhibition could be recovered and long-term acclimation could shorten the recovery process. Notably, increasing nitrite consumption appeared during aerobic phase with the concentration of FNA below 1.46 x 10(-3) mg x L(-1). It was also observed that the phosphorus uptake properties of the sludge varied after long-term inhibition. Nitrate and nitrite type anoxic phosphorus uptake capacity was increased by 3.35 and 3.86 times, respectively, suggesting long-term dosing FNA may facilitate the denitrifying of polyphosphate in organisms utilizing nitrite as electron acceptor. Moreover, long-term acclimation favored sludge settling.
A study of 32P-phosphate uptake in a plant by a real-time RI imaging system
International Nuclear Information System (INIS)
Yamawaki, M.; Kanno, S.; Ishibashi, H.; Noda, A.; Hirose, A.; Tanoi, K.; Nakanishi, T.M.
2011-01-01
It is very important to visualize the process of nutrient absorption and distribution to study the physiological activity of the plant. We developed a real-time radioisotope (RI) imaging system, where RI tracers were applied to the plant sample. This system allowed the quantitative measurement concerning the uptake of nutrients labeled with radioisotopes, such as 45 Ca, 35 S, 32 P and 14 C as long as several days. The β-rays emitted from the sample were converted to light by a CsI(Tl) scintillator and were guided to a highly sensitive CCD camera. The scintillator surface was covered with an Al plate to avoid LED light penetration but allow selected β-ray penetration. We employed Lotus japonicus for the plant sample and observed the 32 P-phosphate absorption in roots and the accumulation to the aboveground part of the plant. The environment condition of daytime and night was simulated by the ON/OFF of LED timer and the accumulation manner of the 32 P-phosphate in roots and leaves during daytime and night was analyzed. The accumulation of 32 P-phosphate in leaves was highly dependant on light irradiation and higher when the LEDs was turned on, whereas the absorption of 32 P-phosphate in root was higher when the LEDs was turned off. The transfer function concerning the transportation of phosphate within the plant during the developmental stage was obtained from the analysis of 32 P uptake images. We are now trying to get specific moving images of each radioisotope when two kinds of isotopes, such as 32 P and 32 S, were applied at the same time to the plant, through an image analysis. (orig.)
International Nuclear Information System (INIS)
Pinto, Vanda; Pinho, Maria Joao; Jose, Pedro A.; Soares-da-Silva, Patricio
2010-01-01
Research highlights: → H 2 O 2 in excess is required for the presence of a low-affinity high-capacity component for the Na + -dependent [ 14 C]-L-alanine uptake in SHR PTE cells only. → It is suggested that Na + binding in renal ASCT2 may be regulated by ROS in SHR PTE cells. -- Abstract: The presence of high and low sodium affinity states for the Na + -dependent [ 14 C]-L-alanine uptake in immortalized renal proximal tubular epithelial (PTE) cells was previously reported (Am. J. Physiol. 293 (2007) R538-R547). This study evaluated the role of H 2 O 2 on the Na + -dependent [ 14 C]-L-alanine uptake of ASCT2 in immortalized renal PTE cells from Wistar Kyoto rat (WKY) and spontaneously hypertensive rat (SHR). Na + dependence of [ 14 C]-L-alanine uptake was investigated replacing NaCl with an equimolar concentration of choline chloride in vehicle- and apocynin-treated cells. Na + removal from the uptake solution abolished transport activity in both WKY and SHR PTE cells. Decreases in H 2 O 2 levels in the extracellular medium significantly reduced Na + -K m and V max values of the low-affinity high-capacity component in SHR PTE cells, with no effect on the high-affinity low-capacity state of the Na + -dependent [ 14 C]-L-alanine uptake. After removal of apocynin from the culture medium, H 2 O 2 levels returned to basal values within 1 to 3 h in both WKY and SHR PTE cells and these were found stable for the next 24 h. Under these experimental conditions, the Na + -K m and V max of the high-affinity low-capacity state were unaffected and the low-affinity high-capacity component remained significantly decreased 1 day but not 4 days after apocynin removal. In conclusion, H 2 O 2 in excess is required for the presence of a low-affinity high-capacity component for the Na + -dependent [ 14 C]-L-alanine uptake in SHR PTE cells only. It is suggested that Na + binding in renal ASCT2 may be regulated by ROS in SHR PTE cells.
ABEE, T; SIEBERS, A; ALTENDORF, K; KONINGS, WN
1992-01-01
Cells of the purple nonsulfur bacterium Rhodobacter sphaeroides express a high-affinity K+ uptake system when grown in media with low K+ concentrations. A vanadate-sensitive, K+-stimulated and Mg2+-stimulated ATPase was purified from membranes of these cells by solubilization with
Vertical partitioning of phosphate uptake among picoplankton groups in the low Pi Mediterranean Sea
Talarmin, Agathe Anne Gaelle; Van Wambeke, F.; Lebaron, P.; Moutin, T.
2015-01-01
Microbial transformations are key processes in marine phosphorus cycling. In this study, we investigated the contribution of phototrophic and heterotrophic groups to phosphate (Pi) uptake fluxes in the euphotic zone of the low-Pi Mediterranean Sea and estimated Pi uptake kinetic characteristics. Surface soluble reactive phosphorus (SRP) concentrations were in the range of 6-80 nmol Lg'1 across the transect, and the community Pi turnover times, assessed using radiolabeled orthophosphate incubations, were longer in the western basin, where the highest bulk and cellular rates were measured. Using live cell sorting, four vertical profiles of Pi uptake rates were established for heterotrophic prokaryotes (Hprok), phototrophic picoeukaryotes (Pic) and Prochlorococcus (Proc) and Synechococcus (Syn) cyanobacteria. Hprok cells contributed up to 82% of total Pi uptake fluxes in the superficial euphotic zone, through constantly high abundances (2.7-10.2 × 105 cells mLg'1) but variable cellular rates (6.6 ± 9.3 amol P cellg'1 hg'1). Cyanobacteria achieved most of the Pi uptake (up to 62%) around the deep chlorophyll maximum depth, through high abundances (up to 1.4 × 105 Proc cells mLg'1) and high cellular uptake rates (up to 40 and 402 amol P cellg'1 hg'1, respectively for Proc and Syn cells). At saturating concentrations, maximum cellular rates up to 132 amol P cellg'1 hg'1 were measured for Syn at station (St.) C, which was 5 and 60 times higher than Proc and Hprok, respectively. Pi uptake capabilities of the different groups likely contribute to their vertical distribution in the low Pi Mediterranean Sea, possibly along with other energy limitations.
Vertical partitioning of phosphate uptake among picoplankton groups in the low Pi Mediterranean Sea
Talarmin, Agathe Anne Gaelle
2015-02-26
Microbial transformations are key processes in marine phosphorus cycling. In this study, we investigated the contribution of phototrophic and heterotrophic groups to phosphate (Pi) uptake fluxes in the euphotic zone of the low-Pi Mediterranean Sea and estimated Pi uptake kinetic characteristics. Surface soluble reactive phosphorus (SRP) concentrations were in the range of 6-80 nmol Lg\\'1 across the transect, and the community Pi turnover times, assessed using radiolabeled orthophosphate incubations, were longer in the western basin, where the highest bulk and cellular rates were measured. Using live cell sorting, four vertical profiles of Pi uptake rates were established for heterotrophic prokaryotes (Hprok), phototrophic picoeukaryotes (Pic) and Prochlorococcus (Proc) and Synechococcus (Syn) cyanobacteria. Hprok cells contributed up to 82% of total Pi uptake fluxes in the superficial euphotic zone, through constantly high abundances (2.7-10.2 × 105 cells mLg\\'1) but variable cellular rates (6.6 ± 9.3 amol P cellg\\'1 hg\\'1). Cyanobacteria achieved most of the Pi uptake (up to 62%) around the deep chlorophyll maximum depth, through high abundances (up to 1.4 × 105 Proc cells mLg\\'1) and high cellular uptake rates (up to 40 and 402 amol P cellg\\'1 hg\\'1, respectively for Proc and Syn cells). At saturating concentrations, maximum cellular rates up to 132 amol P cellg\\'1 hg\\'1 were measured for Syn at station (St.) C, which was 5 and 60 times higher than Proc and Hprok, respectively. Pi uptake capabilities of the different groups likely contribute to their vertical distribution in the low Pi Mediterranean Sea, possibly along with other energy limitations.
Proadifen-sensitive high affinity binding of /sup 3/H-alaproclate to liver membranes
Energy Technology Data Exchange (ETDEWEB)
Ross, S.B.
1987-01-01
/sup 3/H-alaproclate, a selective 5/sub h/ydroxytryptamine uptake inhibitor, was found to bind to microsomal membranes from the rat liver with high affinity (K/sub D/-=3 nM) and large capacity (B/sub max/ about 2 nmol/g liver). This binding was stereoselective since S-( - )-alaproclate was 30 times more potent than the R-( + )-enantiomer to displace the /sup 3/H-labelled racemate. Proadifen (SKF 525A), an inhibitor of cytochrome P-450, displaced the /sup 3/H-alaproclate binding with the same, high affinity (K/sub i/=3 nM) as alaproclate itself. Repeated treatment with phenobarbital sodium (5x75 mg/kg intraperitoneally) increased the number of alaproclate binding sites 7-8 times without changing the affinity. However, most of the phenobarbital induced /sup 3/H-alaproclate binding was not displaceable by proadifen, showing the presence of at least two different high affinity binding sites. The possible involvement of cytochrome P-450 in the alaproclate binding is discussed.
High affinity binding of [3H]cocaine to rat liver microsomes
International Nuclear Information System (INIS)
El-Maghrabi, E.A.; Calligaro, D.O.; Eldefrawi, M.E.
1988-01-01
] 3 H]cocaine bound reversible, with high affinity and stereospecificity to rat liver microsomes. Little binding was detected in the lysosomal, mitochondrial and nuclear fractions. The binding kinetics were slow and the kinetically calculated K/sub D/ was 2 nM. Induction of mixed function oxidases by phenobarbital did not produce significant change in [ 3 H]cocaine binding. On the other hand, chronic administration of cocaine reduced [ 3 H]cocaine binding drastically. Neither treatment affected the affinity of the liver binding protein for cocaine. Microsomes from mouse and human livers had less cocaine-binding protein and lower affinity for cocaine than those from rat liver. Binding of [ 3 H]cocaine to rat liver microsomes was insensitive to monovalent cations and > 10 fold less sensitive to biogenic amines than the cocaine receptor in rat striatum. However, the liver protein had higher affinity for cocaine and metabolites except for norcocaine. Amine uptake inhibitors displaced [ 3 H]cocaine binding to liver with a different rank order of potency than their displacement of [ 3 H]cocaine binding to striatum. This high affinity [ 3 H]cocaine binding protein in liver is not likely to be monooxygenase, but may have a role in cocaine-induced hepatotoxicity
Hudek, L; Premachandra, D; Webster, W A J; Bräu, L
2016-11-01
In bacteria, limited phosphate availability promotes the synthesis of active uptake systems, such as the Pst phosphate transport system. To understand the mechanisms that facilitate phosphate accumulation in the cyanobacterium Nostoc punctiforme, phosphate transport systems were identified, revealing a redundancy of Pst phosphate uptake systems that exists across three distinct operons. Four separate PstB system components were identified. pstB1 was determined to be a suitable target for creating phenotypic mutations that could result in the accumulation of excessive levels of phosphate through its overexpression or in a reduction of the capacity to accumulate phosphate through its deletion. Using quantitative real-time PCR (qPCR), it was determined that pstB1 mRNA levels increased significantly over 64 h in cells cultured in 0 mM added phosphate and decreased significantly in cells exposed to high (12.8 mM) phosphate concentrations compared to the level in cells cultured under normal (0.8 mM) conditions. Possible compensation for the loss of PstB1 was observed when pstB2, pstB3, and pstB4 mRNA levels increased, particularly in cells starved of phosphate. The overexpression of pstB1 increased phosphate uptake by N. punctiforme and was shown to functionally complement the loss of PstB in E. coli PstB knockout (PstB - ) mutants. The knockout of pstB1 in N. punctiforme did not have a significant effect on cellular phosphate accumulation or growth for the most part, which is attributed to the compensation for the loss of PstB1 by alterations in the pstB2, pstB3, and pstB4 mRNA levels. This study provides novel in vivo evidence that PstB1 plays a functional role in phosphate uptake in N. punctiforme IMPORTANCE: Cyanobacteria have been evolving over 3.5 billion years and have become highly adept at growing under limiting nutrient levels. Phosphate is crucial for the survival and prosperity of all organisms. In bacteria, limited phosphate availability promotes the
Silkin, V A; Chubchikova, I N
2007-01-01
We studied nonstationary kinetics of the uptake of phosphates and nitrates by the red marine algae Gelidium latifolium (Grev.) Born et Thur. and calculated constants of the Michaelis-Menten equation for these elements. In the area of 0-3 microM, the kinetics of phosphate consumption had the following coefficients: maximum rate of uptake 0.8 micromol/(g x h), constant of half-saturation 1.745 microM. For nitrate nitrogen at 0-30 microM, an adaptive strategy of uptake kinetics was noted with change of the equation parameters with time: after 1 h, the maximum rate of uptake was 5.1 micromol/(g x h) and constant of half-saturation 19 gM, while within 2 h, the maximum rate of uptake significantly increased. This could be related to the synthesis of nitrate reductase. Coupled with the uptake of nitrates, nonstationary kinetics of the release of nitrates in the surrounding medium had a one-peak pattern: the maximum concentration of nitrites in the medium and the time of its achievement increased with the initial concentration of nitrates. The maximum concentration of nitrites was 6 to 14% of the initial concentration in the medium.
Gomes, Marcelo Pedrosa; Maccario, Sophie; Lucotte, Marc; Labrecque, Michel; Juneau, Philippe
2015-12-15
Phosphate (PO4(3-)) fertilization is a common practice in agricultural fields also targets for glyphosate application. Due to their chemical similarities, PO4(3-) and glyphosate compete for soil adsorbing sites, with PO4(3-) fertilization increasing glyphosate bioavailability in the soil solution. After PO4(3-) fertilization, its concentration will be elevated in the soil solution and both PO4(3-) and glyphosate will be readily available for runoff into aquatic ecosystems. In this context, man-made riparian buffer strips (RBS) at the interface of agricultural lands and waterways can be used as a green technology to mitigate water contamination. The plants used in RBS form a barrier to agricultural wastes that can limit runoff, and the ability of these plants to take up these compounds through their roots plays an important role in RBS efficacy. However, the implications of PO4(3-) for glyphosate uptake by roots are not yet clearly demonstrated. Here, we addressed this problem by hydroponically cultivating willow plants in nutrient solutions amended with glyphosate and different concentrations of PO4(3-), assuring full availability of both chemicals to the roots. Using a phosphate carrier inhibitor (phosphonophormic acid-PFA), we found that part of the glyphosate uptake is mediated by PO4(3-) transporters. We observed, however, that PO4(3-) increased glyphosate uptake by roots, an effect that was related to increased root cell membrane stability. Our results indicate that PO4(3-) has an important role in glyphosate physiological effects. Under agricultural conditions, PO4(3-) fertilization can amplify glyphosate efficiency by increasing its uptake by the roots of undesired plants. On the other hand, since simultaneous phosphate and glyphosate runoffs are common, non-target species found near agricultural fields can be affected. Copyright © 2015. Published by Elsevier B.V.
Zhang, Xu; Shi, Heping; Wu, Jiaxi; Zhang, Xuewu; Sun, Lijun; Chen, Chuo; Chen, Zhijian J.
2013-01-01
The presence of microbial or self DNA in the cytoplasm of mammalian cells is a danger signal detected by the DNA sensor cyclic-GMP-AMP (cGAMP) synthase (cGAS), which catalyzes the production of cGAMP that in turn serves as a second messenger to activate innate immune responses. Here we show that endogenous cGAMP in mammalian cells contains two distinct phosphodiester linkages, one between 2′-OH of GMP and 5′-phosphate of AMP, and the other between 3′-OH of AMP and 5′-phosphate of GMP. This molecule, termed 2′3′-cGAMP, is unique in that it binds to the adaptor protein STING with a much greater affinity than cGAMP molecules containing other combinations of phosphodiester linkages. The crystal structure of STING bound to 2′3′-cGAMP revealed the structural basis of this high-affinity binding and a ligand-induced conformational change in STING that may underlie its activation. PMID:23747010
Zhang, Xu; Shi, Heping; Wu, Jiaxi; Zhang, Xuewu; Sun, Lijun; Chen, Chuo; Chen, Zhijian J
2013-07-25
The presence of microbial or self DNA in the cytoplasm of mammalian cells is a danger signal detected by the DNA sensor cyclic-GMP-AMP (cGAMP) synthase (cGAS), which catalyzes the production of cGAMP that in turn serves as a second messenger to activate innate immune responses. Here we show that endogenous cGAMP in mammalian cells contains two distinct phosphodiester linkages, one between 2'-OH of GMP and 5'-phosphate of AMP, and the other between 3'-OH of AMP and 5'-phosphate of GMP. This molecule, termed 2'3'-cGAMP, is unique in that it binds to the adaptor protein STING with a much greater affinity than cGAMP molecules containing other combinations of phosphodiester linkages. The crystal structure of STING bound to 2'3'-cGAMP revealed the structural basis of this high-affinity binding and a ligand-induced conformational change in STING that may underlie its activation. Copyright © 2013 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Latzkovits, L.; Neidle, A.; Lajtha, A.
1984-01-01
In measurements of high affinity transport in tissue slices, the incubation medium is often treated as an ''infinitely large pool''. External substrate concentrations, even at the micromolar level, are assumed to be constant and metabolic interactions between tissue and medium are neglected. In the present report we describe experiments in which glutamic and aspartic acid uptake by mouse brain slices were studied using techniques that could test these assumptions. Cerebral hemispheres were cut into 0.1 mm sections and about 90 mg of tissue incubated in 10 ml of oxygenated medium. After 45 minutes of equilibration, radioactive substrates were added and the concentrations and specific activities of the amino acids and their metabolites in the medium were determined. During the first 10 min following substrate addition, rapid decreases in glutamic and aspartic acid concentrations in the medium were accompanied by large decreases in specific activity caused by the continuous release of these amino acids from the tissue. In addition, extensive conversion of both substrates to glutamine and the preferential accumulation of this metabolite, in the medium, was found. These results demonstrate that metabolism and release occur simultaneously with uptake during transport experiments in vitro and that these processes can take place in specific tissue compartments. It is therefore necessary to measure the tissue and medium concentration levels of amino acids along with their radioactivity in such experiments, since all three processes (transport, metabolism, and compartmentation) are interrelated in the clearance of amino acids from the incubation medium and probably from the extracellular spaces in vivo as well
Tate, Cathy M.; Broshears, Robert E.; McKnight, Diane M.
1995-01-01
Acid mine drainage streams in the Rocky Mountains typically have few algal species and abundant iron oxide deposits which can sorb phosphate. An instream injection of radiolabeled phosphate (32P0,) into St. Kevin Gulch, an acid mine drainage stream, was used to test the ability of a dominant algal species, Ulothrix sp., to rapidly assimilate phosphate. Approximately 90% of the injected phosphate was removed from the water column in the 175-m stream reach. When shaded stream reaches were exposed to full sunlight after the injection ended, photoreductive dissolution of iron oxide released sorbed 32P, which was then also removed downstream. The removal from the stream was modeled as a first-order process by using a reactive solute transport transient storage model. Concentrations of 32P mass-’ of algae were typically lo-fold greater than concentrations in hydrous iron oxides. During the injection, concentrations of 32P increased in the cellular P pool containing soluble, low-molecular-weight compounds and confirmed direct algal uptake of 32P0, from water. Mass balance calculations indicated that algal uptake and sorption on iron oxides were significant in removing phosphate. We conclude that in stream ecosystems, PO, sorbed by iron oxides can act as a dynamic nutrient reservoir regulated by photoreduction.
Anawar, Hossain M; Rengel, Zed; Damon, Paul; Tibbett, Mark
2018-02-01
High arsenic (As) concentrations in the soil, water and plant systems can pose a direct health risk to humans and ecosystems. Phosphate (Pi) ions strongly influence As availability in soil, its uptake and toxicity to plants. Better understanding of As(V)-Pi interactions in soils and plants will facilitate a potential remediation strategy for As contaminated soils, reducing As uptake by crop plants and toxicity to human populations via manipulation of soil Pi content. However, the As(V)-Pi interactions in soil-plant systems are complex, leading to contradictory findings among different studies. Therefore, this review investigates the role of soil type, soil properties, minerals, Pi levels in soil and plant, Pi transporters, mycorrhizal association and microbial activities on As-Pi interactions in soils and hydroponics, and uptake by plants, elucidate the key mechanisms, identify key knowledge gaps and recommend new research directions. Although Pi suppresses As uptake by plants in hydroponic systems, in soils it could either increase or decrease As availability and toxicity to plants depending on the soil types, properties and charge characteristics. In soil, As(V) availability is typically increased by the addition of Pi. At the root surface, the Pi transport system has high affinity for Pi over As(V). However, Pi concentration in plant influences the As transport from roots to shoots. Mycorrhizal association may reduce As uptake via a physiological shift to the mycorrhizal uptake pathway, which has a greater affinity for Pi over As(V) than the root epidermal uptake pathway. Copyright © 2017 Elsevier Ltd. All rights reserved.
Characterization of a high affinity cocaine binding site in rat brain
International Nuclear Information System (INIS)
Calligaro, D.; Eldefrawi, M.
1986-01-01
Binding of [ 3 H]cocaine to synaptic membranes from whole rat brain was reversible and saturable. Nonlinear regression analysis of binding isotherms indicated two binding affinities: one with k/sub d/ = 16 nM, B/sub max/ = 0.65 pmoles/mg protein and the other with K/sub d/ = 660 nM, B/sub max/ = 5.1 pmoles/mg protein. The high-affinity binding of [ 3 H]cocaine was sensitive to the actions of trypsin and chymotrypsin but not carboxypeptidase, and was eliminated by exposure of the membranes to 95 0 C for 5 min. Specific binding at 2 nM was higher at pH 8.8 than at pH 7.0. Binding of [ 3 H]cocaine (15 nM) was inhibited by increasing concentrations of Na + ions. Several cocaine analogues, neurotransmitter uptake inhibitors and local anesthetics displaced specific [ 3 H]cocaine binding at 2 nM with various potencies. The cocaine analogue (-)-norcocaine was the most potent (IC 50 = 10 nM), while the local anesthetic tetracaine was the least potent in inhibiting [ 3 H]cocaine binding. Several biogenic amine uptake inhibitors, including tricyclic antidepressants and phencyclidine, had IC 50 values below μM concentrations
Xie, Xianan; Lin, Hui; Peng, Xiaowei; Xu, Congrui; Sun, Zhongfeng; Jiang, Kexin; Huang, Antian; Wu, Xiaohui; Tang, Nianwu; Salvioli, Alessandra; Bonfante, Paola; Zhao, Bin
2016-12-05
The majority of terrestrial vascular plants are capable of forming mutualistic associations with obligate biotrophic arbuscular mycorrhizal (AM) fungi from the phylum Glomeromycota. This mutualistic symbiosis provides carbohydrates to the fungus, and reciprocally improves plant phosphate uptake. AM fungal transporters can acquire phosphate from the soil through the hyphal networks. Nevertheless, the precise functions of AM fungal phosphate transporters, and whether they act as sensors or as nutrient transporters, in fungal signal transduction remain unclear. Here, we report a high-affinity phosphate transporter GigmPT from Gigaspora margarita that is required for AM symbiosis. Host-induced gene silencing of GigmPT hampers the development of G. margarita during AM symbiosis. Most importantly, GigmPT functions as a phosphate transceptor in G. margarita regarding the activation of the phosphate signaling pathway as well as the protein kinase A signaling cascade. Using the substituted-cysteine accessibility method, we identified residues A 146 (in transmembrane domain [TMD] IV) and Val 357 (in TMD VIII) of GigmPT, both of which are critical for phosphate signaling and transport in yeast during growth induction. Collectively, our results provide significant insights into the molecular functions of a phosphate transceptor from the AM fungus G. margarita. Copyright © 2016 The Author. Published by Elsevier Inc. All rights reserved.
Characterization of taurine binding, uptake, and release in the rat hypothalamus
International Nuclear Information System (INIS)
Hanretta, A.T.
1985-01-01
The neurotransmitter criteria of specific receptors, inactivation, and release were experimentally examined for taurine in the hypothalamus. Specific membrane binding and synaptosomal uptake of taurine both displayed high affinity and low affinity systems. The neurotransmitter criterion of release was studied in superfused synaptosomes. Exposure of synaptosomes which had been preloaded with a concentration of [ 3 H]taurine in the high affinity uptake range (1.5 μM) to either 56 mM K + or 100 μM veratridine evoked a Ca 2+ -independent release. Exposure of synaptosomes which had been preloaded with a concentration of [ 3 H]taurine in the low affinity uptake range (2 mM) to 56 mM K + induced a Ca 2+ -independent release, whereas 100 + M veratridine did not, either in the presence or absence of Ca 2+ . Based on these results, as well as other observations, a model is proposed in which the high affinity uptake system is located on neuronal membranes and the low affinity uptake system is located on glial membranes. The mechanisms of binding, uptake, and release in relation to the cellular location of each are discussed. We conclude that the neurotransmitter criterion of activation by re-uptake is satisfied for taurine in the hypothalamus. However, the failure to demonstrate both a specific taurine receptor site and a Ca 2+ -dependent evoked release, necessitates that we conclude that taurine appears not to function as a hypothalamic neurotransmitter, at least not in the classical sense
Energy Technology Data Exchange (ETDEWEB)
N' Guessan, L.A.; Elifantz, H.; Nevin, K.P.; Mouser, P.J.; Methe, B.; Woodard, T. L.; Manley, K.; Williams, K. H.; Wilkins, M. J.; Larsen, J.T.; Long, P. E.; Lovley, D. R.
2009-09-01
Nutrient limitation is an environmental stress that may reduce the effectiveness of bioremediation strategies, especially when the contaminants are organic compounds or when organic compounds are added to promote microbial activities such as metal reduction. Genes indicative of phosphate-limitation were identified via microarray analysis of chemostat cultures of Geobacter sulfureducens. This analysis revealed that genes in the pst-pho operon, which is associated with a high affinity phosphate uptake system in other microorganisms, had significantly higher transcript abundance under phosphate-limiting conditions, with the genes pstB and phoU the most up-regulated. Quantitative PCR analysis of pstB and phoU transcript levels in G. sulfurreducens grown in chemostats demonstrated that the expression of these genes increased when phosphate was removed from the culture medium. Transcripts of pstB and phoU within the subsurface Geobacter species predominating during an in situ uranium bioremediation field experiment were more abundant than in chemostat cultures of G. sulfurreducens that were not limited for phosphate. Addition of phosphate to incubations of subsurface sediments did not stimulate dissimilatory metal reduction. The added phosphate was rapidly adsorbed onto the sediments. The results demonstrate that Geobacter species can effectively reduce U(VI) even when experiencing suboptimal phosphate concentrations and that increasing phosphate availability with phosphate additions is difficult to achieve due to the high reactivity of this compound. This transcript-based approach developed for diagnosing phosphate limitation should be applicable to assessing the potential need for additional phosphate in other bioremediation processes.
Low affinity uniporter carrier proteins can increase net substrate uptake rate by reducing efflux
Bosdriesz, Evert; Wortel, Meike T.; Haanstra, Jurgen R.; Wagner, Marijke J.; De La Torre Cortés, Pilar; Teusink, Bas
2018-01-01
Many organisms have several similar transporters with different affinities for the same substrate. Typically, high-affinity transporters are expressed when substrate is scarce and low-affinity ones when it is abundant. The benefit of using low instead of high-affinity transporters remains unclear,
Low affinity uniporter carrier proteins can increase net substrate uptake rate by reducing efflux
Bosdriesz, Evert; Wortel, M.T.; Haanstra, Jurgen R.; Wagner, Marijke J.; De La Torre, P.; Teusink, Bas
2018-01-01
Many organisms have several similar transporters with different affinities for the same substrate. Typically, high-affinity transporters are expressed when substrate is scarce and low-affinity ones when it is abundant. The benefit of using low instead of high-affinity transporters remains
Cao, Hui; Jia, Xueping; Shi, Jian; Xiao, Jianbo; Chen, Xiaoqing
2016-07-01
Dietary stilbenoids are associated with many benefits for human health, which depend on their bioavailability and bioaccessibility. The stilbenoid-human serum albumin (HSA) interactions are investigated to explore the structure-affinity relationship and influence on the stability, free radical scavenging activity and cell uptake of stilbenoids. The structure-affinity relationship of the stilbenoids-HSA interaction was found as: (1) the methoxylation enhanced the affinity, (2) an additional hydroxyl group increases the affinity and (3) the glycosylation significantly weakened the affinity. HSA obviously masked the free radical scavenging potential of stilbenoids. The stabilities of stilbenoids in different medium were determined as: HSA solution>human plasma>Dulbecco's modified Eagle's medium. It appears that the milk enhanced the cell uptake of stilbenoids with multi-hydroxyl groups and weakened the cell uptake of stilbenoids with methoxyl group on EA.hy 926 endothelial cells. The stilbenoids are hardly absorbed by human umbilical vein endothelial cells in the presence of milk. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Giovanni Ulloa
2018-02-01
Full Text Available Recently, we reported the production of Cadmium sulfide (CdS fluorescent semiconductor nanoparticles (quantum dots, QDs by acidophilic bacteria of the Acidithiobacillus genus. Here, we report that the addition of inorganic phosphate to Acidithiobacillus thiooxidans ATCC 19703 cultures favors the biosynthesis of CdS QDs at acidic conditions (pH 3.5. The effect of pH, phosphate and cadmium concentrations on QDs biosynthesis was studied by using Response Surface Methodology (RSM, a multivariate technique for analytical optimization scarcely used in microbiological studies to date. To address how phosphate affects intracellular biosynthesis of CdS QDs, the effect of inorganic phosphate on bacterial cadmium-uptake was evaluated. By measuring intracellular levels of cadmium we determined that phosphate influences the capacity of cells to incorporate this metal. A relation between cadmium tolerance and phosphate concentrations was also determined, suggesting that phosphate participates in the adaptation of bacteria to toxic levels of this metal. In addition, QDs-biosynthesis was also favored by the degradation of intracellular polyphosphates. Altogether, our results indicate that phosphate contributes to A. thiooxidans CdS QDs biosynthesis by influencing cadmium uptake and cadmium tolerance. These QDs may also be acting as a nucleation point for QDs formation at acidic pH. This is the first study reporting the effect of phosphates on QDs biosynthesis and describes a new cadmium-response pathway present in A. thiooxidans and most probably in other bacterial species.
Ulloa, Giovanni; Quezada, Carolina P.; Araneda, Mabel; Escobar, Blanca; Fuentes, Edwar; Álvarez, Sergio A.; Castro, Matías; Bruna, Nicolás; Espinoza-González, Rodrigo; Bravo, Denisse; Pérez-Donoso, José M.
2018-01-01
Recently, we reported the production of Cadmium sulfide (CdS) fluorescent semiconductor nanoparticles (quantum dots, QDs) by acidophilic bacteria of the Acidithiobacillus genus. Here, we report that the addition of inorganic phosphate to Acidithiobacillus thiooxidans ATCC 19703 cultures favors the biosynthesis of CdS QDs at acidic conditions (pH 3.5). The effect of pH, phosphate and cadmium concentrations on QDs biosynthesis was studied by using Response Surface Methodology (RSM), a multivariate technique for analytical optimization scarcely used in microbiological studies to date. To address how phosphate affects intracellular biosynthesis of CdS QDs, the effect of inorganic phosphate on bacterial cadmium-uptake was evaluated. By measuring intracellular levels of cadmium we determined that phosphate influences the capacity of cells to incorporate this metal. A relation between cadmium tolerance and phosphate concentrations was also determined, suggesting that phosphate participates in the adaptation of bacteria to toxic levels of this metal. In addition, QDs-biosynthesis was also favored by the degradation of intracellular polyphosphates. Altogether, our results indicate that phosphate contributes to A. thiooxidans CdS QDs biosynthesis by influencing cadmium uptake and cadmium tolerance. These QDs may also be acting as a nucleation point for QDs formation at acidic pH. This is the first study reporting the effect of phosphates on QDs biosynthesis and describes a new cadmium-response pathway present in A. thiooxidans and most probably in other bacterial species. PMID:29515535
Uptake of [N-Me-3H]-choline by synaptosomes from the central nervous system of Locusta migratoria
International Nuclear Information System (INIS)
Breer, H.
1982-01-01
The accumulation of 3H-choline by isolated synaptosomes from the central nervous system of locust was studied at concentrations varying from 0.05 to 40 microM. Kinetic analysis of the saturable process revealed a high-affinity and a low-affinity system. The high-affinity uptake was competitively inhibited by hemicholinium-3 and was absolutely dependent on external sodium. Elevated potassium concentrations inhibited choline uptake. The choline uptake by insect synaptosomes was found to be remarkably resistant to a variety of metabolic inhibitors. The reduced choline uptake under depolarizing conditions (high potassium concentration or veratridine) in the absence of calcium implies that electrochemical gradients are important for high-affinity choline uptake. Depolarization of preloaded synaptosomes under appropriate conditions resulted in a significant release of newly accumulated choline radioactivity
Energy Technology Data Exchange (ETDEWEB)
Hao, Z.; Reiske, H.R.; Wilson, D.B.
1999-11-01
Two different Cd{sup 2+} uptake systems were identified in Lactobacillus plantarum. One is a high-affinity, high-velocity Mn{sup 2+} uptake system which also takes up Cd{sup 2+} and is induced by Mn{sup 2+} starvation. The calculated K{sub m} and V{sub max} are 0.26 {mu}M and 3.6 {mu}mol g of dry cell{sup {minus}1} min{sup {minus}1}, respectively. Unlike Mn{sup 2+} uptake, which is facilitated by citrate and related tricarboxylic acids, Cd{sup 2+} uptake is weakly inhibited by citrate. Cd{sup 2+} and Mn{sup 2+} are competitive inhibitors of each other, and the affinity of the system for Cd{sup 2+} is higher than that for Mn{sup 2+}. The other Cd{sup 2+} uptake system is expressed in Mn{sup 2+}-sufficient cells, and no K{sub m} can be calculated for it because uptake is nonsaturable. Mn{sup 2+} does not compete for transport through this system, nor does any other tested cation, i.e., Zn{sup 2+}, Cu{sup 2+}, Co{sup 2+}, Mg{sup 2+}, Ca{sup 2+}, Fe{sup 2+}, or Ni{sup 2+}. Both systems require energy, since uncouplers completely inhibit their activities. Two Mn{sup 2+}-dependent L. plantarum mutants were isolated by chemical mutagenesis and ampicillin enrichment. They required more than 5,000 times as much Mn{sup 2+} for growth as the parental strain. Mn{sup 2+} starvation-induced Cd{sup 2+} uptake in both mutants was less than 5% the wild-type rate. The low level of long-term Mn{sup 2+} or Cd{sup 2+} accumulation by the mutant strains also shows that the mutations eliminate the high-affinity Mn{sup 2+} and Cd{sup 2+} uptake system.
Krueger, R D; Harper, S H; Campbell, J W; Fahrney, D E
1986-01-01
The archaebacterium Methanobacterium thermoautotrophicum was grown in continuous culture at 65 degrees C in a phosphate-limited medium at specific growth rates from 0.06 to 0.28 h-1 (maximum growth rate [mu max] = 0.36 h-1). Cyclic-2,3-diphosphoglycerate (cyclic DPG) levels ranged from 2 to 20 mM in Pi-limited cells, compared with about 30 mM in batch-grown cells. The Monod constant for Pi-limited growth was 5 nM. Pi uptake rates were determined by following the disappearance of 32Pi from the...
International Nuclear Information System (INIS)
Rodriguez-Puertas, R.; Pazos, A.; Zarranz, J.J.; Pascual, J.
1994-01-01
H-hemicholinium-3 (H-HC-3) binding, a marker of the presynaptic high-affinity choline uptake carrier (HACU), was measured by autoradiography in several brain regions of 17 Alzheimer's disease (AD) patients and of 11 matched controls. A significant decrease in the density of H-HC-3 binding sites was found in entorhinal cortex, hippocampus and layers I-III of the frontal cortex. By contrast, in the caudate-putamen the number of H-HC-3 binding sites in AD cases was comparable to that of control striata. These data concur with previous results using classical presynaptic markers and reflect the loss in the activity of HACU, and, hence, in the synthesis of acetylcholine, that selectively occurs in cortical areas of AD brains due to the degeneration of presynaptic cholinergic terminals arising from the basal forebrain. However, the relatively low mean reduction in HACU in cortical areas (-40 %), together with the apparent indemnity of this marker in certain severely demented AD cases, suggest that AD dementia cannot be explained simply by the loss of presynaptic terminals originating in the basal forebrain. These data seem to be a good explanation for the poor response to cholinergic replacement in AD. (author)
International Nuclear Information System (INIS)
Wahid, F.; Sharif, M.; Khan, M. A.; Khan, S. A.
2016-01-01
The beneficial microbes like arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) are known to play an important role in phosphorous (P) supply to plants in a sustainable manner in P deficient soils. In this scenario, a pot experiment was conducted under greenhouse condition to assess the synergistic effect of AMF and PSB strains (Coccus DIM7 Streptococcus PIM6 and Bacillus sp. PIS7) on P solubility from RP and their successive uptake by maize (Zea-mays L. Azam) crop at alkaline soil. The experiment was completely randomized design with three replications having calcareous silty clay loam soil, low in organic matter, nitrogen and phosphorus contents. RP was used as a crude phosphate alone and/or in combination with the native AMF and PSB inoculum. The Results indicated that the rhizosphere interactions between AMF and PSB significantly promote RP mineralization in soil and improved all growth parameters including shoot (56 percent), root yield (52 percent), height (41 percent), N (80 percent) and P (91 percent) uptake by the maize plants as compared to control and single inoculation. A remarkable increase in soil spore density, PSB population and percent root colonization in maize plants were also recorded by the combined inoculation of AMF and PSB with RP. From this study, it is concluded that the combined application of AMF and PSB with RP has the potential to improve maize growth and nutrients uptake. Moreover, AMF and PSB inoculants are recommended as useful biofertilizers for enhancing P solubility and bioavailability in P deficient agricultural soils. (author)
Phosphopeptide enrichment by immobilized metal affinity chromatography
DEFF Research Database (Denmark)
Thingholm, Tine E.; Larsen, Martin R.
2016-01-01
Immobilized metal affinity chromatography (IMAC) has been the method of choice for phosphopeptide enrichment prior to mass spectrometric analysis for many years and it is still used extensively in many laboratories. Using the affinity of negatively charged phosphate groups towards positively...... charged metal ions such as Fe3+, Ga3+, Al3+, Zr4+, and Ti4+ has made it possible to enrich phosphorylated peptides from peptide samples. However, the selectivity of most of the metal ions is limited, when working with highly complex samples, e.g., whole-cell extracts, resulting in contamination from...
International Nuclear Information System (INIS)
Hynes, M.D.; Lochner, M.A.; Bemis, K.G.; Hymson, D.L.
1985-01-01
The analgesic effect of morphine in the rat tail jerk assay was enhanced by the serotonin uptake inhibitor, fluoxetine. Tail jerk latency was not affected by fluoxetine alone. Morphine's affinity for opioid receptors labeled in vitro with 3 H-naloxone or 3 H-D-Ala 2 -D-Leu 5 -enkephalin was not altered by fluoxetine, which has no affinity for these sites at concentrations as high as 1000 nM. In rats trained to discriminate morphine from saline, fluoxetine at doses of 5 or 10 mg/kg were recognized as saline. Increasing the fluoxetine dose to 20 mg/kg did not result in generalization to either saline or morphine. The dose response curve for morphine generalization was not significantly altered by fluoxetine doses of 5 or 10 mg/kg. Those rats treated with the combination of morphine and 20 mg/kg of fluoxetine did not exhibit saline or morphine appropriate responding. Fluoxetine potentiates the analgesic properties of morphine without enhancing its affinity for opioid receptors or its discriminative stimulus properties. 30 references, 2 figures, 2 tables
Downregulation of taurine uptake in multidrug resistant Ehrlich ascites tumor cells
DEFF Research Database (Denmark)
Poulsen, K A; Litman, Thomas; Eriksen, J
2002-01-01
In daunorubicin resistant Ehrlich ascites tumor cells (DNR), the initial taurine uptake was reduced by 56% as compared to the parental, drug sensitive Ehrlich cells. Kinetic experiments indicated that taurine uptake in Ehrlich cells occurs via both high- and low-affinity transporters. The maximal...... rate constant for the initial taurine uptake was reduced by 45% (high-affinity system) and 49% (low affinity system) in the resistant subline whereas the affinity of the transporters to taurine was unchanged. By immunoblotting we identified 3 TauT protein bands in the 50-70 kDa region. A visible...... reduction in the intensity of the band with the lowest molecular weight was observed in resistant cells. Quantitative RT-PCR indicated a significant reduction in the amount of taurine transporter mRNA in the resistant cells. Drug resistance in DNR Ehrlich cells is associated with overexpression of the mdr1...
International Nuclear Information System (INIS)
Chen, De; Guo, Hu; Li, Ruiyue; Li, Lianqing; Pan, Genxing; Chang, Andrew; Joseph, Stephen
2016-01-01
Biochar is becoming an environmentally friendly material for remediation of heavy metal contaminated soils and improving food safety. A field trial over four rice seasons was conducted to investigate the use of biochar and low Cd accumulating cultivars on Cd uptake in a heavy metal contaminated soil. Wheat straw derived biochar was applied at 0, 20 and 40 t ha"−"1. Two rice cultivars with differing Cd accumulation abilities were selected in each season. The results showed that both biochar and low Cd affinity cultivars significantly reduced rice grain Cd accumulation. Biochar had no significant effect the first season but thereafter consistently reduced rice grain Cd by a maximum of 61, 86 and 57% over the next three seasons. Zn accumulation in the rice grains was not decreased by biochar application, although available soil Zn was sharply reduced (35–91%). Indica conventional rice cultivars had much lower Cd, but higher Zn and lower Cd/Zn ratios in the grain than indica hybrid cultivars. Biochar was more effective for mitigating grain Cd accumulation in low Cd affinity cultivars than in high affinity cultivars. Soil pH was sustainably increased (up to nearly 1 unit) while available Cd significantly decreased by a maximum of 85% after biochar addition. The translocation of Cd from rice roots to shoots was reduced from 20 to 80% by biochar. Low uptake affinity cultivars combined with biochar reduced late rice grain Cd concentration and Cd/Zn ratios by 69–80% and 72–80%, respectively. It indicated that the management of combining biochar and low Cd affinity cultivars should be an efficient way to remediate Cd contaminated rice paddies and reduce health risk associated with consuming rice from these soils. - Highlights: • Biochar sustainably reduced soil Cd availability and Cd translocation in rice plant. • Indica conventional cultivars had lower Cd but higher Zn in grains than hybrid ones. • Biochar significantly reduced grain Cd and Cd/Zn ratio, though
Yañez, Fernando; Chianella, Iva; Piletsky, Sergey A; Concheiro, Angel; Alvarez-Lorenzo, Carmen
2010-02-05
This work has focused on the rational development of polymers capable of acting as traps of bile salts. Computational modeling was combined with molecular imprinting technology to obtain networks with high affinity for cholate salts in aqueous medium. The screening of a virtual library of 18 monomers, which are commonly used for imprinted networks, identified N-(3-aminopropyl)-methacrylate hydrochloride (APMA.HCl), N,N-diethylamino ethyl methacrylate (DEAEM) and ethyleneglycol methacrylate phosphate (EGMP) as suitable functional monomers with medium-to-high affinity for cholic acid. The polymers were prepared with a fix cholic acid:functional monomer mole ratio of 1:4, but with various cross-linking densities. Compared to polymers prepared without functional monomer, both imprinted and non-imprinted microparticles showed a high capability to remove sodium cholate from aqueous medium. High affinity APMA-based particles even resembled the performance of commercially available cholesterol-lowering granules. The imprinting effect was evident in most of the networks prepared, showing that computational modeling and molecular imprinting can act synergistically to improve the performance of certain polymers. Nevertheless, both the imprinted and non-imprinted networks prepared with the best monomer (APMA.HCl) identified by the modeling demonstrated such high affinity for the template that the imprinting effect was less important. The fitting of adsorption isotherms to the Freundlich model indicated that, in general, imprinting increases the population of high affinity binding sites, except when the affinity of the functional monomer for the target molecule is already very high. The cross-linking density was confirmed as a key parameter that determines the accessibility of the binding points to sodium cholate. Materials prepared with 9% mol APMA and 91% mol cross-linker showed enough affinity to achieve binding levels of up to 0.4 mmol g(-1) (i.e., 170 mg g(-1)) under flow
Directory of Open Access Journals (Sweden)
Zhaoyun Wu
Full Text Available BACKGROUND: Phosphorus is one of the macronutrients essential for plant growth and development. The acquisition and translocation of phosphate are pivotal processes of plant growth. In a large number of plants, phosphate uptake by roots and translocation within the plant are presumed to occur via a phosphate/proton cotransport mechanism. PRINCIPAL FINDINGS: We cloned two cDNAs from soybean (Glycine max, GmPT1 and GmPT2, which show homology to the phosphate/proton cotransporter PHO84 from the budding yeast Saccharomyces cerevisiae. The amino acid sequence of the products predicted from GmPT1 and GmPT2 share 61% and 63% identity, respectively, with the PHO84 in amino acid sequence. The deduced structure of the encoded proteins revealed 12 membrane-spanning domains with a central hydrophilic region. The molecular mass values are ∼58.7 kDa for GmPT1 and ∼58.6 kDa for GmPT2. Transiently expressed GFP-protein fusions provide direct evidence that the two Pi transporters are located in the plasma membrane. Uptake of radioactive orthophosphate by the yeast mutant MB192 showed that GmPT1 and GmPT2 are dependent on pH and uptake is reduced by the addition of uncouplers of oxidative phosphorylation. The K(m for phosphate uptake by GmPT1 and GmPT2 is 6.65 mM and 6.63 mM, respectively. A quantitative real time RT-PCR assay indicated that these two genes are expressed in the roots and shoots of seedlings whether they are phosphate-deficient or not. Deficiency of phosphorus caused a slight change of the expression levels of GmPT1 and GmPT2. CONCLUSIONS: The results of our experiments show that the two phosphate transporters have low affinity and the corresponding genes are constitutively expressed. Thereby, the two phosphate transporters can perform translocation of phosphate within the plant.
International Nuclear Information System (INIS)
Roos, Per; Jakobsen, Iver
2008-01-01
Uptake of metals from uranium-rich phosphate rock was studied in Medicago truncatula plants grown in symbiosis with the arbuscular mycorrhizal fungus Glomus intraradices or in the absence of mycorrhizas. Shoot concentrations of uranium and thorium were lower in mycorrhizal than in non-mycorrhizal plants and root-to-shoot ratio of most metals was increased by mycorrhizas. This protective role of mycorrhizas was observed even at very high supplies of phosphate rock. In contrast, phosphorus uptake was similar at all levels of phosphate rock, suggesting that the P was unavailable to the plant-fungus uptake systems. The results support the role of arbuscular mycorrhiza as being an important component in phytostabilization of uranium. This is the first study to report on mycorrhizal effect and the uptake and root-to-shoot transfer of thorium from phosphate rock
Energy Technology Data Exchange (ETDEWEB)
Roos, Per [Radiation Research Department, Riso National Laboratory, Technical University of Denmark, DK-4000 Roskilde (Denmark); Jakobsen, Iver [Biosystems Department, Riso National Laboratory, Technical University of Denmark, DK-4000 Roskilde (Denmark)], E-mail: iver.jakobsen@risoe.dk
2008-05-15
Uptake of metals from uranium-rich phosphate rock was studied in Medicago truncatula plants grown in symbiosis with the arbuscular mycorrhizal fungus Glomus intraradices or in the absence of mycorrhizas. Shoot concentrations of uranium and thorium were lower in mycorrhizal than in non-mycorrhizal plants and root-to-shoot ratio of most metals was increased by mycorrhizas. This protective role of mycorrhizas was observed even at very high supplies of phosphate rock. In contrast, phosphorus uptake was similar at all levels of phosphate rock, suggesting that the P was unavailable to the plant-fungus uptake systems. The results support the role of arbuscular mycorrhiza as being an important component in phytostabilization of uranium. This is the first study to report on mycorrhizal effect and the uptake and root-to-shoot transfer of thorium from phosphate rock.
Novel and high affinity fluorescent ligands for the serotonin transporter based on (s)-citalopram
DEFF Research Database (Denmark)
Kumar, Vivek; Rahbek-Clemmensen, Troels; Billesbølle, Christian B
2014-01-01
Novel rhodamine-labeled ligands, based on (S)-citalopram, were synthesized and evaluated for uptake inhibition at the human serotonin, dopamine, and norepinephrine transporters (hSERT, hDAT, and hNET, respectively) and for binding at SERT, in transiently transfected COS7 cells. Compound 14 demons...... demonstrated high affinity binding and selectivity for SERT (K i = 3 nM). Visualization of SERT, using confocal laser scanning microscopy, validated compound 14 as a novel tool for studying SERT expression and distribution in living cells....
Measuring the serotonin uptake site using [3H]paroxetine--a new serotonin uptake inhibitor
International Nuclear Information System (INIS)
Gleiter, C.H.; Nutt, D.J.
1988-01-01
Serotonin is an important neurotransmitter that may be involved in ethanol preference and dependence. It is possible to label the serotonin uptake site in brain using the tricyclic antidepressant imipramine, but this also binds to other sites. We have used the new high-affinity uptake blocker paroxetine to define binding to this site and report it to have advantages over imipramine as a ligand
Energy Technology Data Exchange (ETDEWEB)
Hao, Z.; Chen, S.; Wilson, D.B.
1999-11-01
An Mn{sup 2+} and Cd{sup 2+} uptake gene, mntA, was cloned from Lactobacillus plantarum ATCC 14917 into Escherichia coli. Its expression conferred on E. coli cells increased Cd{sup 2+} sensitivity as well as energy-dependent Cd{sup 2+} uptake activity. Both transcription and translation of mntA were induced by Mn{sup 2+} starvation in L. plantarum, as indicated by reverse transcriptase PCR and immunoblotting. Two Cd{sup 2+} uptake systems have been identified in L. plantarum: one is a high-affinity Mn{sup 2+} and Cd{sup 2+} uptake system that is expressed in Mn{sup 2+}-starved cells, and the other is a nonsaturable Cd{sup 2+} uptake system that is expressed in Cd{sup 2+}-sufficient cells. MntA was not detected in an Mn{sup 2+}-dependent mutant of L. plantarum which had lost high-affinity Mn{sup 2+} and Cd{sup 2+} uptake activity. The results suggest that mntA is the gene encoding the high-affinity Mn{sup 2+} and Cd{sup 2+} transporter. On the basis of its predicted amino acid sequence, MntA belongs to the family of P-type cation-translocating ATPases. The topology and potential Mn{sup 2+}- and Cd{sup 2+}-binding sites of MntA are discussed. A second clone containing a low-affinity Cd{sup 2+} transport system was also isolated.
DEFF Research Database (Denmark)
Zhang, Peng; Jørgensen, Trine Nygaard; Løland, Claus Juul
2013-01-01
A novel fluorescent ligand was synthesized as a high-affinity, high specificity probe for visualizing the serotonin transporter (SERT). The rhodamine fluorophore was extended from an aniline substitution on the 5-position of the dihydroisobenzofuran ring of citalopram (2, 1-(3-(dimethylamino......)propyl)-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile), using an ethylamino linker. The resulting rhodamine-labeled ligand 8 inhibited [3H]5-HT uptake in COS-7 cells (Ki = 225 nM) with similar potency to the tropane-based JHC 1-064 (1), but with higher specificity towards the SERT relative...
Qi, Zhi; Hampton, Corrina R; Shin, Ryoung; Barkla, Bronwyn J; White, Philip J; Schachtman, Daniel P
2008-01-01
Caesium (Cs(+)) is a potentially toxic mineral element that is released into the environment and taken up by plants. Although Cs(+) is chemically similar to potassium (K(+)), and much is known about K(+) transport mechanisms, it is not clear through which K(+) transport mechanisms Cs(+) is taken up by plant roots. In this study, the role of AtHAK5 in high affinity K(+) and Cs(+) uptake was characterized. It is demonstrated that AtHAK5 is localized to the plasma membrane under conditions of K(+) deprivation, when it is expressed. Growth analysis showed that AtHAK5 plays a role during severe K(+) deprivation. Under K(+)-deficient conditions in the presence of Cs(+), Arabidopsis seedlings lacking AtHAK5 had increased inhibition of root growth and lower Cs(+) accumulation, and significantly higher leaf chlorophyll concentrations than wild type. These data indicate that, in addition to transporting K(+) in planta, AtHAK5 also transports Cs(+). Further experiments showed that AtHAK5 mediated Cs(+) uptake into yeast cells and that, although the K(+) deficiency-induced expression of AtHAK5 was inhibited by low concentrations of NH(4)(+) in planta, Cs(+) uptake by yeast was stimulated by low concentrations of NH(4)(+). Interestingly, the growth of the Arabidopsis atakt1-1 mutant was more sensitive to Cs(+) than the wild type. This may be explained, in part, by increased expression of AtHAK5 in the atakt1-1 mutant. It is concluded that AtHAK5 is a root plasma membrane uptake mechanism for K(+) and Cs(+) under conditions of low K(+) availability.
Energy Technology Data Exchange (ETDEWEB)
Chen, De; Guo, Hu; Li, Ruiyue [Institute of Resources, Ecosystem and Environment of Agriculture, and Center of Biochar and Green Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Li, Lianqing, E-mail: lqli@njau.edu.cn [Institute of Resources, Ecosystem and Environment of Agriculture, and Center of Biochar and Green Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Pan, Genxing [Institute of Resources, Ecosystem and Environment of Agriculture, and Center of Biochar and Green Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); Chang, Andrew [Department of Environmental Sciences, University of California, Riverside, CA 92521 (United States); Joseph, Stephen [Institute of Resources, Ecosystem and Environment of Agriculture, and Center of Biochar and Green Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing 210095 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)
2016-01-15
Biochar is becoming an environmentally friendly material for remediation of heavy metal contaminated soils and improving food safety. A field trial over four rice seasons was conducted to investigate the use of biochar and low Cd accumulating cultivars on Cd uptake in a heavy metal contaminated soil. Wheat straw derived biochar was applied at 0, 20 and 40 t ha{sup −1}. Two rice cultivars with differing Cd accumulation abilities were selected in each season. The results showed that both biochar and low Cd affinity cultivars significantly reduced rice grain Cd accumulation. Biochar had no significant effect the first season but thereafter consistently reduced rice grain Cd by a maximum of 61, 86 and 57% over the next three seasons. Zn accumulation in the rice grains was not decreased by biochar application, although available soil Zn was sharply reduced (35–91%). Indica conventional rice cultivars had much lower Cd, but higher Zn and lower Cd/Zn ratios in the grain than indica hybrid cultivars. Biochar was more effective for mitigating grain Cd accumulation in low Cd affinity cultivars than in high affinity cultivars. Soil pH was sustainably increased (up to nearly 1 unit) while available Cd significantly decreased by a maximum of 85% after biochar addition. The translocation of Cd from rice roots to shoots was reduced from 20 to 80% by biochar. Low uptake affinity cultivars combined with biochar reduced late rice grain Cd concentration and Cd/Zn ratios by 69–80% and 72–80%, respectively. It indicated that the management of combining biochar and low Cd affinity cultivars should be an efficient way to remediate Cd contaminated rice paddies and reduce health risk associated with consuming rice from these soils. - Highlights: • Biochar sustainably reduced soil Cd availability and Cd translocation in rice plant. • Indica conventional cultivars had lower Cd but higher Zn in grains than hybrid ones. • Biochar significantly reduced grain Cd and Cd/Zn ratio
Griffiths, N. A.; Mulholland, P. J.
2011-12-01
We used the Tracer Additions for Spiraling Curve Characterization (TASCC) approach to quantify seasonal variability in ambient nutrient spiraling metrics and nutrient uptake kinetics in the West Fork of Walker Branch, a forested headwater stream in eastern Tennessee, USA. We performed instantaneous additions of nitrate (NO3-) and phosphate (PO4-3) separately with a conservative tracer (chloride, Cl-) during the following biologically-important time periods: autumn (during leaf fall, high organic matter [OM] standing stocks), winter (low OM standing stocks), spring (prior to canopy closure), and summer (closed canopy). We predicted that nutrient demand would be highest during autumn and spring, as OM inputs fuel heterotrophic respiration and high light availability stimulates autotrophic production, respectively. The measured ambient PO4-3 uptake rates (Vf-amb) followed our predictions, with the highest Vf-amb rates in autumn (Vf-amb = 2.8 mm/min) and spring (Vf-amb = 2.9 mm/min), and undetectable uptake in winter. Further, maximum areal PO4-3 uptake rates (Umax) were higher in autumn (Umax = 297 μg/m2/min) than spring (Umax = 106 μg/m2/min), possibly due to greater nutrient demand of heterotrophs on leaf litter accumulations. Contrary to our predictions, ambient NO3- uptake rates were highest in autumn and winter (autumn: Vf-amb = 2.8 mm/min, winter: Vf-amb = 2.4 mm/min), and lowest in spring (Vf-amb = 1.0 mm/min). The higher than expected Vf-amb rate in winter may be due to higher stream metabolism rates and thus greater nitrogen demand; the lower than expected Vf-amb rate in spring may reflect an alleviation of nitrogen demand due to high ammonium concentrations during this time. As the demand for both nitrogen and phosphorus in Walker Branch is greatest in autumn, future work will characterize how nutrient metrics change during this dynamic time period (i.e., before, during, and after leaf fall).
International Nuclear Information System (INIS)
Pichot, J.; Truong, B.; Beunard, P.
1979-01-01
Six natural West African phosphates are compared with a weak Tunisian phosphate and triple superphosphate in five types of tropical soil. The study consists of a pot experiment using Agrostis as the test plant, over several cuttings, in order to evaluate the uptake of phosphorus by plants and the isotopically dilutable phosphorus of the soil (L-value). The results show that there are very great differences between phosphates from the points of view of speed and degree of solubilization and that the L-value is a good criterion for assessing these differences. (author)
International Nuclear Information System (INIS)
Oliveira, Letúzia M. de; Lessl, Jason T.; Gress, Julia; Tisarum, Rujira; Guilherme, Luiz R.G.; Ma, Lena Q.
2015-01-01
We investigated the effects of chromate (CrVI) and phosphate (P) on their uptake and translocation in As-hyperaccumulator Pteris vittata (PV). Plants were exposed to 1) 0.10 mM CrVI and 0, 0.25, 1.25, or 2.50 mM P or 2) 0.25 mM P and 0, 0.50, 2.5 or 5.0 mM CrVI for 24 h in hydroponics. PV accumulated 2919 mg/kg Cr in the roots at CrVI 0.10 , and 5100 and 3500 mg/kg P in the fronds and roots at P 0.25 . When co-present, CrVI and P inhibited each other's uptake in PV. Increasing P concentrations reduced Cr root concentrations by 62–82% whereas increasing CrVI concentrations reduced frond P concentrations by 52–59% but increased root P concentrations by 11–15%. Chromate reduced P transport, with more P being accumulated in PV roots. Though CrVI was supplied, 64−78% and 92−93% CrIII were in PV fronds and roots. Based on X-ray diffraction, Cr 2 O 3 was detected in the roots confirming CrVI reduction to CrIII by PV. In short, CrVI and P inhibited each other in uptake and translocation by PV, and CrVI reduction to CrIII in PV roots served as its detoxification mechanism. The finding helps to understand the interactions of P and Cr during their uptake in PV. - Highlights: • Phosphate and CrVI inhibited each other in uptake and translocation by Pteris vittata. • P. vittata was more efficient in CrVI uptake than CrIII, but little Cr being translocated to the fronds. • CrVI was provided in the media, but 64–78% and 92–93% CrIII were in the fronds and roots of P. vittata. • CrVI was taken up by P. vittata and reduced to CrIII in the roots possibly as Cr 2 O 3 . - Pteris vittata was efficient in CrVI uptake, concentrating in the roots after reducing to CrIII
International Nuclear Information System (INIS)
Karanja, N.K.; Mwendwa, K.A.
2002-01-01
A series of studies were carried out to study the effect of P application on fast growing multi-purpose trees. A greenhouse experiment was conducted to evaluate availability and uptake of phosphorus (P) from Minjingu phosphate rock (MPR). An acid soil and six agroforestry tree species namely Leucena leuco-cephala, Gliricidia sepium, Sesbania sesban, Grevillea robusta, Cassia siamea and Eucalyptus grandis were used. Phosphorus was applied at 25.8 mg P/ kg soil as Minjingu phosphate rock (MPR) or Triple Superphosphate (TSP). Pregerminated seedlings were transplanted and divided into two sequential harvests at 3 and 6 MAT (months after transplanting). 32 P isotope carrier free solution was added to transplanted seedlings at the beginning and when they were 3 months old. The soil was tested for isotopically exchangeable P by incubating the soil with the MPR and TSP. The soil was high in P-fixing capacity. At 3 MAT all the species except G. robusta gave a 150-250% significantly higher stem dry weights where P was added and L. leuco-cephala, S. sesban and C. siamea maintained this up to 6 MAT. The legumes and E. grandis where P was applied differed significantly from controls in root dry weight with Minjingu PR being superior with G.sepium and E. grandis. The legumes and E. grandis had significantly higher P uptake where P was applied at 3 MAT. The relative availability of MPR at 3 MAT showed that L.leucocephala and G. sepium derived 2.93 and 1.06 times more P from Minjingu PR than from TSP respectively. Data obtained from G. robusta P uptake showed that this species preferred soil P to externally supplied P in the three sampling periods. Tree species and fertilizer P interactions at 6 MAT were highly significant (P=0.01). Vesicular arbuscular mycorrhiza (VAM) inoculation improved growth, P uptake from MPR and nodulation of G. sepium seedlings. Inoculating L. leucocephala seedlings with VAM increased availability of P from MPR. (author)
Energy Technology Data Exchange (ETDEWEB)
Rodriguez-Puertas, R; Pazos, A [Dept. of Physiology and Pharmacology, Unit of Pharmacology, Univ. of Cantabria, Santander (Spain); Zarranz, J J [Dept. of Neuroscience, Univ. of the Basque Country, Leioa (Spain); Pascual, J [Dept. of Medicine, Service of Neurology, Univ. Hospital ` Marques de Valdecilla` , Univ. of Cantabria, Santander (Spain)
1994-12-31
H-hemicholinium-3 (H-HC-3) binding, a marker of the presynaptic high-affinity choline uptake carrier (HACU), was measured by autoradiography in several brain regions of 17 Alzheimer`s disease (AD) patients and of 11 matched controls. A significant decrease in the density of H-HC-3 binding sites was found in entorhinal cortex, hippocampus and layers I-III of the frontal cortex. By contrast, in the caudate-putamen the number of H-HC-3 binding sites in AD cases was comparable to that of control striata. These data concur with previous results using classical presynaptic markers and reflect the loss in the activity of HACU, and, hence, in the synthesis of acetylcholine, that selectively occurs in cortical areas of AD brains due to the degeneration of presynaptic cholinergic terminals arising from the basal forebrain. However, the relatively low mean reduction in HACU in cortical areas (-40 %), together with the apparent indemnity of this marker in certain severely demented AD cases, suggest that AD dementia cannot be explained simply by the loss of presynaptic terminals originating in the basal forebrain. These data seem to be a good explanation for the poor response to cholinergic replacement in AD. (author).
Comparison between Arabidopsis and Rice for Main Pathways of K+ and Na+ Uptake by Roots
Nieves-Cordones, Manuel; Mart?nez, Vicente; Benito, Bego?a; Rubio, Francisco
2016-01-01
K+ is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K+ in the soil solution are widely variable, K+ nutrition is secured by uptake systems that exhibit different affinities for K+. Two main systems have been described for root K+ uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K+ uptake, a...
Uptake of Radionuclide Metals by SPME Fibers
International Nuclear Information System (INIS)
Duff, M; S Crump, S; Robert Ray, R; Keisha Martin, K; Donna Beals, D
2006-08-01
The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating high explosive (HE) and fire debris (FD) evidence while maintaining evidentiary value. One experimental method for the isolation of HE and FD residue involves using solid phase microextraction or SPME fibers to remove residue of interest. Due to their high affinity for organics, SPME fibers should have little affinity for most metals. However, no studies have measured the affinity of radionuclides for SPME fibers. The focus of this research was to examine the affinity of dissolved radionuclide ( 239/240 Pu, 238 U, 237 Np, 85 Sr, 133 Ba, 137 Cs, 60 Co and 226 Ra) and stable radionuclide surrogate metals (Sr, Co, Ir, Re, Ni, Ba, Cs, Nb, Zr, Ru, and Nd) for SPME fibers at the exposure conditions that favor the uptake of HE and FD residues. Our results from radiochemical and mass spectrometric analyses indicate these metals have little measurable affinity for these SPME fibers during conditions that are conducive to HE and FD residue uptake with subsequent analysis by liquid or gas phase chromatography with mass spectrometric detection
Solution structure of the Grb2 SH2 domain complexed with a high-affinity inhibitor
International Nuclear Information System (INIS)
Ogura, Kenji; Shiga, Takanori; Yokochi, Masashi; Yuzawa, Satoru; Burke, Terrence R.; Inagaki, Fuyuhiko
2008-01-01
The solution structure of the growth factor receptor-bound protein 2 (Grb2) SH2 domain complexed with a high-affinity inhibitor containing a non-phosphorus phosphate mimetic within a macrocyclic platform was determined by nuclear magnetic resonance (NMR) spectroscopy. Unambiguous assignments of the bound inhibitor and intermolecular NOEs between the Grb2 SH2 domain and the inhibitor was accomplished using perdeuterated Grb2 SH2 protein. The well-defined solution structure of the complex was obtained and compared to those by X-ray crystallography. Since the crystal structure of the Grb2 SH2 domain formed a domain-swapped dimer and several inhibitors were bound to a hinge region, there were appreciable differences between the solution and crystal structures. Based on the binding interactions between the inhibitor and the Grb2 SH2 domain in solution, we proposed a design of second-generation inhibitors that could be expected to have higher affinity
Uptake of the proteins HTRA1 and HTRA2 by cells mediated by calcium phosphate nanoparticles
Directory of Open Access Journals (Sweden)
Olga Rotan
2017-02-01
Full Text Available The efficient intracellular delivery of (biomolecules into living cells remains a challenge in biomedicine. Many biomolecules and synthetic drugs are not able to cross the cell membrane, which is a problem if an intracellular mode of action is desired, for example, with a nuclear receptor. Calcium phosphate nanoparticles can serve as carriers for small and large biomolecules as well as for synthetic compounds. The nanoparticles were prepared and colloidally stabilized with either polyethyleneimine (PEI; cationic nanoparticles or carboxymethyl cellulose (CMC; anionic nanoparticles and loaded with defined amounts of the fluorescently labelled proteins HTRA1, HTRA2, and BSA. The nanoparticles were purified by ultracentrifugation and characterized by dynamic light scattering and scanning electron microscopy. Various cell types (HeLa, MG-63, THP-1, and hMSC were incubated with fluorescently labelled proteins alone or with protein-loaded cationic and anionic nanoparticles. The cellular uptake was followed by light and fluorescence microscopy, confocal laser scanning microscopy (CLSM, and flow cytometry. All proteins were readily transported into the cells by cationic calcium phosphate nanoparticles. Notably, only HTRA1 was able to penetrate the cell membrane of MG-63 cells in dissolved form. However, the application of endocytosis inhibitors revealed that the uptake pathway was different for dissolved HTRA1 and HTRA1-loaded nanoparticles.
Russo-Abrahão, Thais; Lacerda-Abreu, Marco Antônio; Gomes, Tainá; Cosentino-Gomes, Daniela; Carvalho-de-Araújo, Ayra Diandra; Rodrigues, Mariana Figueiredo; Oliveira, Ana Carolina Leal de; Rumjanek, Franklin David; Monteiro, Robson de Queiroz; Meyer-Fernandes, José Roberto
2018-01-01
Recent studies demonstrate that interstitial inorganic phosphate is significantly elevated in the breast cancer microenvironment as compared to normal tissue. In addition it has been shown that breast cancer cells express high levels of the NaPi-IIb carrier (SLC34A2), suggesting that this carrier may play a role in breast cancer progression. However, the biochemical behavior of inorganic phosphate (Pi) transporter in this cancer type remains elusive. In this work, we characterize the kinetic parameters of Pi transport in the aggressive human breast cancer cell line, MDA-MB-231, and correlated Pi transport with cell migration and adhesion. We determined the influence of sodium concentration, pH, metabolic inhibitors, as well as the affinity for inorganic phosphate in Pi transport. We observed that the inorganic phosphate is dependent on sodium transport (K0,5 value = 21.98 mM for NaCl). Furthermore, the transport is modulated by different pH values and increasing concentrations of Pi, following the Michaelis-Menten kinetics (K0,5 = 0.08 mM Pi). PFA, monensin, furosemide and ouabain inhibited Pi transport, cell migration and adhesion. Taken together, these results showed that the uptake of Pi in MDA-MB-231 cells is modulated by sodium and by regulatory mechanisms of intracellular sodium gradient. General Significance: Pi transport might be regarded as a potential target for therapy against tumor progression.
Chen, Liang; Zhao, Xin; Pan, Bingcai; Zhang, Weixian; Hua, Ming; Lv, Lu; Zhang, Weiming
2015-03-02
In this study, we employed a new nanocomposite adsorbent HZO-201, which featured high stability under varying solution chemistry, for preferable removal of phosphate from synthetic solution and a real effluent. An anion exchange resin (D-201) was employed as the host of HZO-201, where nano-hydrous zirconium oxide (HZO) was encapsulated as the active species. D-201 binds phosphate through nonspecific electrostatic affinity, whereas the loaded HZO nanoparticles capture phosphate through formation of the inner-sphere complexes. Quantitative contribution of both species to phosphate adsorption was predicted based on the double-Langmuir model. Preferable removal of phosphate by HZO-201 was observed in the presence of the competing anions at higher levels (Cl(-), NO3(-), SO4(2-), HCO3(-)). Fixed-bed adsorption indicated that the effective volume capacity of a synthetic water (2.0 mg P-PO4(3-)/L) by using HZO-201 was ∼1600 BV in the first run (<0.5mg P-PO4(3-)/L), comparable to Fe(III)-based nanocomposite HFO-201 (∼1500 BV) and much larger than D-201 (<250 BV). The exhausted HZO-201 can be in situ regenerated by using a binary NaOH-NaCl solution for cyclic runs, whether fed with the synthetic solution or real effluent. In general, HZO-201 is a promising alternative to Fe(III)-based adsorbents for trace phosphate removal from effluent particularly at acidic pH. Copyright © 2014 Elsevier B.V. All rights reserved.
Evaluation of available phosphorus and cadmium associated with phosphate rock for direct application
International Nuclear Information System (INIS)
Chien, S.H.
2002-01-01
Three greenhouse experiments were conducted to evaluate available P and Cd associated with the use of phosphate rock (PR) for direct application. These experiments were: (1) 'Estimation of Phosphorus Availability to Maize and Cowpea From Phosphate Rock as Enhanced by Water-Soluble Phosphorus'; (2) 'Modified Iron Oxide-Impregnated Paper Strip (Pi) Test for Soils Treated With Phosphate Fertilizers'; and (3) 'Effect of Acidulation of High Cadmium Containing Phosphate Rocks on Cadmium Uptake by Upland Rice'. In the first experiment, a medium-reactive Central Florida phosphate rock (PR) was used. The effectiveness of P sources in terms of increasing dry-matter yield and P uptake followed the order of TSP≥(PR+TSP)>PR for maize and TSP=(TSP+PR)>PR for cowpea. P uptake from PR in the presence of TSP was higher than P uptake from PR applied alone. With respect to P uptake from PR applied alone, the corresponding relative increase in P uptake from PR due to TSP influence was 165% for maize and 72% for cowpea. In the second experiment, a highly reactive North Carolina PR was used. Both Bray I and the Pi test (with CaCl 2 ) underestimated available P from PR with respect to TSP. Available P estimated by the Pi test with KCl was more closely related to P uptake with both PR and TSP. More P was extracted from PR by the Pi test with KCl than with CaCl 2 , whereas no effect was observed for TSP. In the third experiment, a low-reactive Togo PR and a highly reactive North Carolina PR were used. Both PRs were fully acidulated to SSP and Togo PR was also partially acidulated with H 2 SO 4 at 50% level to PAPR. Cd uptake by rice grain followed the order of NC-SSP > NC-PR and Togo-SSP > Togo PAPR > Togo PR. The results also showed that most of the Cd uptake was retained in rice root and straw. Total uptake of Cd, Ca, and P by the rice plant was higher from NC-PR than from Togo-PR. Cd concentration in rice grain showed no significant difference between NC-PR and Togo-PR, whereas Cd
Directory of Open Access Journals (Sweden)
Qurban Ali Panhwar
2013-01-01
Full Text Available A study was conducted at Universiti Putra Malaysia to determine the effect of phosphate-solubilizing bacteria (PSB and organic acids (oxalic & malic on phosphate (P solubilization from phosphate rock (PR and growth of aerobic rice. Four rates of each organic acid (0, 10, 20, and 30 mM, and PSB strain (Bacillus sp. were applied to aerobic rice. Total bacterial populations, amount of P solubilization, P uptake, soil pH, and root morphology were determined. The results of the study showed significantly high P solubilization in PSB with organic acid treatments. Among the two organic acids, oxalic acid was found more effective compared to malic acid. Application of oxalic acid at 20 mM along with PSB16 significantly increased soluble soil P (28.39 mg kg−1, plant P uptake (0.78 P pot−1, and plant biomass (33.26 mg. Addition of organic acids with PSB and PR had no influence on soil pH during the planting period. A higher bacterial population was found in rhizosphere (8.78 log10 cfu g−1 compared to the nonrhizosphere and endosphere regions. The application of organic acids along with PSB enhanced soluble P in the soil solution, improved root growth, and increased plant biomass of aerobic rice seedlings without affecting soil pH.
International Nuclear Information System (INIS)
Mortvedt, J.J.
1984-01-01
Plant uptake of heavy metals such as Cd and Zn applied to soil as contaminants in P fertilizers is of concern because of their possible entry into the human food chain. Concentrations in P fertilizers generally range from 1 to 50 mg kg/sup -1/ of Cd and 50 to 500 mg kg/sup -1/ of Zn, but much higher concentrations have been reported. Such wide ranges are due to variations in heavy metal contents of phosphate rock (PR) used to produce P fertilizers. Samples of vegetable tissues grown in New York on soil fertilized with triple superphosphate (TSP) for nine years of a 10-year experiment were analyzed for Cd and Zn. Results of this study show that plant availability of Cd and Zn contaminants in P fertilizers is rather low, even at high rates of P fertilization
International Nuclear Information System (INIS)
Stoyanova, I.; Rankov, V.; Dimitrov, G.
1978-01-01
The uptake of phosphates by tomato plants, cv.Hebros, was assessed by 32 P in a vegetation pot experiment. Leached meadow-cinnamon soil was used, taken from a stationary field experiment to which, for a period of eight years, various rates of NPK were applied. As a result of that significant changes occurred in the soil nutrient substance supplies (concerning total and mobile forms of nitrogen, phosphorus, potassium, pH and salts concentration). It was established that the coefficient of phasphate utilization by tomato plants was the highest (19.15%) on soil receiving a N 210 P 210 K 210 fertilizer application. Long-term fertilization with higher rates at a 1:1:1 NPK ratio increased the content of nutrient substances in the soil, but the coefficient of utilization of available phosphate diminished and was lowest (11.40%) in the case when a N 960 P 960 K 720 mineral fertilizer rate was applied. Following prolonged mineral fertilization with growing N rates (from 240 up to 720 kg/ha) at a background of P 720 K 210 , the coefficient of phosphate utilization by tomato plants also diminished from 16.16 to 12.26%. (author)
Aguda, Adeleke H; Lavallee, Vincent; Cheng, Ping; Bott, Tina M; Meimetis, Labros G; Law, Simon; Nguyen, Nham T; Williams, David E; Kaleta, Jadwiga; Villanueva, Ivan; Davies, Julian; Andersen, Raymond J; Brayer, Gary D; Brömme, Dieter
2016-08-26
Natural products are an important source of novel drug scaffolds. The highly variable and unpredictable timelines associated with isolating novel compounds and elucidating their structures have led to the demise of exploring natural product extract libraries in drug discovery programs. Here we introduce affinity crystallography as a new methodology that significantly shortens the time of the hit to active structure cycle in bioactive natural product discovery research. This affinity crystallography approach is illustrated by using semipure fractions of an actinomycetes culture extract to isolate and identify a cathepsin K inhibitor and to compare the outcome with the traditional assay-guided purification/structural analysis approach. The traditional approach resulted in the identification of the known inhibitor antipain (1) and its new but lower potency dehydration product 2, while the affinity crystallography approach led to the identification of a new high-affinity inhibitor named lichostatinal (3). The structure and potency of lichostatinal (3) was verified by total synthesis and kinetic characterization. To the best of our knowledge, this is the first example of isolating and characterizing a potent enzyme inhibitor from a partially purified crude natural product extract using a protein crystallographic approach.
Trace element affinities in two high-Ge coals from China
Energy Technology Data Exchange (ETDEWEB)
Jing Li; Xinguo Zhuang; Xavier Querol [China University of Geosciences, Wuhan (China). Faculty of Earth Resources
2011-01-15
The Lincang (Yunnan Province, Southwest China) and Wulantuga (Inner Mongolia, Northeast China) coal deposits are known because of the high-Ge content. These coals have also a high concentration of a number of other elements. To determine the mode of occurrence of the enriched elements in both coals, six density fractions from {lt} 1.43 to {gt} 2.8 g/cm{sup 3} were obtained from two representative samples using heavy-liquids. A number of peculiar geochemical patterns characterize these high-Ge coals. Thus, the results of the chemical analysis of these density fractions showed that both coals (very distant and of a different geological age) are highly enriched (compared with the usual worldwide coal concentration ranges) in Ge, As, Sb, W, Be, and Tl. This may be due to similar geochemistry of hydrothermal fluids influencing the Earth Crust in these regions of China. Moreover, Wulantuga coal (Early Cretaceous subbituminous coal) is also enriched in Ca, Mg, and Na, and Lincang coal (Neogene subbituminous coal) in K, Rb, Nb, Mo, Sn, Cs, and U. A group of elements consisting of Ge, W, B, Nb, and Sb mostly occur with an organic affinity in both coals. Additionally, Be, U, and Mo (and partially Mn and Zn) in Lincang, and Na and Mg in Wulantuga occur also with a major organic affinity. Both coals have sulfide-arsenide mineral assemblages (Fe, S, As, Sn, and Pb, and in addition to Tl, Ta, and Cs in the Lincang coal). The occurrence of Al, P, Li, Sc, Ti, V, Cr, and Zr in both coals, and Ba in Lincang, are associated with the mineral assemblage of silico-aluminates and minor heavy minerals. Furthermore, P, Na, Li, Sc, Ti, Ga, Rb, Zr, Cr, Ba, Th, and LREE (La, Ce, Pr, Nd, and Gd) in Lincang are associated with mineral assemblages of phosphates and minor heavy minerals. The two later mineral assemblages are derived from the occurrence of detrital minerals. 34 refs., 7 figs., 3 tabs.
Energy Technology Data Exchange (ETDEWEB)
Selmer, D. [Technische Univ. Muenchen, Freising-Weihenstephan (Germany). Lehrstuhl fuer Phytopathologie; Senekowitsch-Schmidtke, R. [Technische Univ. Muenchen (Germany). Nuklearmedizinische Klinik; Schneider, W. [Steigerwald Arzneimittel, Darmstadt (Germany); Elstner, E.F. [Technische Univ. Muenchen, Freising-Weihenstephan (Germany). Lehrstuhl fuer Phytopathologie
1997-01-01
Specific and unspecific binding and uptake (internalization) by macrophages of {sup 125}iodine-labelled, copper-oxidized human low density lipoprotein is differently influenced by the anti-oxidants {alpha}-tocopherol ({alpha}-Toc), probucol (Prob), pyridoxal-5`-phosphate (PP) and the magnesium-pyridoxal-5`-phosphate glutamate complex (MPPG). Binding as well as internalization, mediated by the so-called `scavenger receptor` is lower in the presence of MPPG whereas both specific binding and internalization are enhanced. The comparison of the effects in vitro allows a rating of the potentially anti-atherogenic and thus protective effects of the tested substances as follows: MPPG>PP>{alpha}-Toc>Prob. (orig.)
DEFF Research Database (Denmark)
Jensen, Claus H; Hansen, Hanne D; Bay, Tina
2017-01-01
understanding of this population of binding sites. With its high specific affinity and monocarboxylate transporter (MCT1) mediated transport across the blood-brain barrier in pharmacological doses, 3-hydroxycyclopent-1-enecarboxylic acid (HOCPCA) seems like a suitable PET radiotracer candidate. Here, we report...... autoradiography on sections of pig brain was performed using [(3)H]HOCPCA. In vivo evaluation of [(11)C]HOCPCA showed no brain uptake, possibly due to a limited uptake of HOCPCA by the MCT1 transporter at tracer doses of [(11)C]HOCPCA....
DEFF Research Database (Denmark)
Revsbech, Inge Grønvall
2016-01-01
The aim of this thesis is to broaden the knowledge of molecular mechanisms of adjustment in oxygen (O2) uptake, conduction, delivery and consumption in mammals adapted to extreme conditions. For this end, I have worked with animals living at high altitude as an example of environmental hypoxia...... of the repeatedly found adaptive traits in animals living at high altitude and in hibernating mammals during hibernation compared with the active state. Factors that affect O2 affinity of Hb include temperature, H+/CO2 via the Bohr effect as well as Cl- and organic phosphates, in mammals mainly 2...
Lewińska, K; Karczewska, A
2013-01-01
Four kinds of soil material were used in a pot experiment with velvetgrass (Holcus lanatus). Two unpolluted soils: sand (S) and loam (L) were spiked with sodium arsenite (As II) and arsenate (As V), to obtain total arsenic (As) concentrations of 500 mg As kg(-1). Two other soils (ZS I, ZS III), containing 3320 and 5350 mg As kg(-1), were collected from Zloty Stok where gold and arsenic ores were mined and processed for several centuries. The effects of phosphate addition on plants growth and As uptake were investigated. Phosphate was applied to soils in the form of NH4H2PO4 at the rate 0.2 g P/kg. Average concentrations of arsenic in the shoots of velvetgrass grown in spiked soils S and L without P amendment were in the range 18-210 mg As kg(-1) d.wt., whereas those in plants grown on ZS I and ZS II soils were considerably lower, and varied in the range 11-52 mg As kg(-1) d.wt. The addition of phosphate caused a significant increase in plant biomass and therefore the total amounts of As taken up by plants, however, the differences in As concentrations in the shoots of velvetgrass amended and non-amended with phosphate were not statistically significant.
On the mechanism of ion exchange in zirconium phosphates
International Nuclear Information System (INIS)
Clearfield, A.; Frianeza, T.N.
1978-01-01
α-titanium phosphate, Ti(HPO 4 ) 2 .H 2 O, was found to form two sodium ion exchanged phases. A half exchanged phase of ideal composition TiNaH(PO 4 ) 2 .4H 2 O formed first. However, before all of the titanium phosphate was converted to this phase a second phase of higher Na + content formed. Thus, a three phase solid existed until sufficient sodium ion uptake (approximately 5.5 meq/g) produced only the two exchanged phases. Finally, the half exchanged phase was converted to the more highly loaded one and this latter phase existed from 6 to 8 meq/g of Na + uptake. Severe disordering of the crystal lattice during exchange is proposed to explain this unusual exchange behavior. A broad range of titanium phosphate-zirconium phosphate solid solutions was found to form. Their behavior towards Na + -H + exchange was determined and interpreted on the basis of the known behavior of the pure phases. Mixed Ti-Zr solid solutions of their pyrophosphates were obtained at elevated temperatures. (author)
Ali, Shahin S.; Nugent, Brian; Mullins, Ewen; Doohan, Fiona M.
2013-01-01
Ethanol is the most-widely used biofuel in the world today. Lignocellulosic plant biomass derived from agricultural residue can be converted to ethanol via microbial bioprocessing. Fungi such as Fusarium oxysporum can simultaneously saccharify straw to sugars and ferment sugars to ethanol. But there are many bottlenecks that need to be overcome to increase the efficacy of microbial production of ethanol from straw, not least enhancement of the rate of fermentation of both hexose and pentose sugars. This research tested the hypothesis that the rate of sugar uptake by F. oxysporum would enhance the ethanol yields from lignocellulosic straw and that high affinity glucose transporters can enhance ethanol yields from this substrate. We characterized a novel hexose transporter (Hxt) from this fungus. The F. oxysporum Hxt represents a novel transporter with homology to yeast glucose signaling/transporter proteins Rgt2 and Snf3, but it lacks their C-terminal domain which is necessary for glucose signalling. Its expression level decreased with increasing glucose concentration in the medium and in a glucose uptake study the Km(glucose) was 0.9 mM, which indicated that the protein is a high affinity glucose transporter. Post-translational gene silencing or over expression of the Hxt in F. oxysporum directly affected the glucose and xylose transport capacity and ethanol yielded by F. oxysporum from straw, glucose and xylose. Thus we conclude that this Hxt has the capacity to transport both C5 and C6 sugars and to enhance ethanol yields from lignocellulosic material. This study has confirmed that high affinity glucose transporters are ideal candidates for improving ethanol yields from lignocellulose because their activity and level of expression is high in low glucose concentrations, which is very common during the process of consolidated processing. PMID:23382943
Directory of Open Access Journals (Sweden)
Shahin S Ali
Full Text Available Ethanol is the most-widely used biofuel in the world today. Lignocellulosic plant biomass derived from agricultural residue can be converted to ethanol via microbial bioprocessing. Fungi such as Fusarium oxysporum can simultaneously saccharify straw to sugars and ferment sugars to ethanol. But there are many bottlenecks that need to be overcome to increase the efficacy of microbial production of ethanol from straw, not least enhancement of the rate of fermentation of both hexose and pentose sugars. This research tested the hypothesis that the rate of sugar uptake by F. oxysporum would enhance the ethanol yields from lignocellulosic straw and that high affinity glucose transporters can enhance ethanol yields from this substrate. We characterized a novel hexose transporter (Hxt from this fungus. The F. oxysporum Hxt represents a novel transporter with homology to yeast glucose signaling/transporter proteins Rgt2 and Snf3, but it lacks their C-terminal domain which is necessary for glucose signalling. Its expression level decreased with increasing glucose concentration in the medium and in a glucose uptake study the Km((glucose was 0.9 mM, which indicated that the protein is a high affinity glucose transporter. Post-translational gene silencing or over expression of the Hxt in F. oxysporum directly affected the glucose and xylose transport capacity and ethanol yielded by F. oxysporum from straw, glucose and xylose. Thus we conclude that this Hxt has the capacity to transport both C5 and C6 sugars and to enhance ethanol yields from lignocellulosic material. This study has confirmed that high affinity glucose transporters are ideal candidates for improving ethanol yields from lignocellulose because their activity and level of expression is high in low glucose concentrations, which is very common during the process of consolidated processing.
International Nuclear Information System (INIS)
Kelly, James; Amor-Coarasa, Alejandro; Williams, Clarence; Ponnala, Shashikanth; Nikolopoulou, Anastasia; Kim, Dohyun; Babich, John W.
2017-01-01
Current clinical imaging of PSMA-positive prostate cancer by positron emission tomography (PET) mainly features "6"8Ga-labeled tracers, notably ["6"8Ga]Ga-PSMA-HBED-CC. The longer half-life of fluorine-18 offers significant advantages over Ga-68, clinically and logistically. We aimed to develop high-affinity PSMA inhibitors labeled with fluorine-18 as alternative tracers for prostate cancer. Six triazolylphenyl ureas and their alkyne precursors were synthesized from the Glu-urea-Lys PSMA binding moiety. PSMA affinity was determined in a competitive binding assay using LNCaP cells. The ["1"8F]triazoles were isolated following a Cu(I)-catalyzed click reaction between the alkynes and ["1"8F]fluoroethylazide. The "1"8F-labeled compounds were evaluated in nude mice bearing LNCaP tumors and compared to ["6"8Ga]Ga-PSMA-HBED-CC and ["1"8F]DCFPyL. Biodistribution studies of the two tracers with the highest imaged-derived tumor uptake and highest PSMA affinity were undertaken at 1 h, 2 h and 4 h post-injection (p.i.), and co-administration of PMPA was used to determine whether uptake was PSMA-specific. F-18-labeled triazolylphenyl ureas were prepared with a decay-corrected RCY of 20-40 %, >98 % radiochemical and chemical purity, and specific activity of up to 391 GBq/μmol. PSMA binding (IC_5_0) ranged from 3-36 nM. The position of the triazole influenced tumor uptake (3 > 4 > 2), and direct conjugation of the triazole with the phenylurea moiety was preferred to insertion of a spacer group. Image-derived tumor uptake ranged from 6-14 %ID/g at 2 h p.i., the time of maximum tumor uptake; uptake of ["6"8Ga]Ga-PSMA-HBED-CC and ["1"8F]DCFPyL was 5-6 %ID/g at 1-3 h p.i., the time of maximum tumor uptake. Biodistribution studies of the two most promising compounds gave maximum tumor uptakes of 10.9 ± 1.0 % and 14.3 ± 2.5 %ID/g, respectively, as compared to 6.27 ± 1.44 %ID/g for ["6"8Ga]Ga-PSMA-HBED-CC. Six ["1"8F]triazolylphenyl ureas were prepared in good radiochemical yield
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Kelly, James; Amor-Coarasa, Alejandro; Williams, Clarence; Ponnala, Shashikanth [Weill Cornell Medicine, Division of Radiopharmaceutical Sciences and Molecular Imaging Innovations Institute, Department of Radiology, New York, NY (United States); Nikolopoulou, Anastasia [Weill Cornell Medicine, Division of Radiopharmaceutical Sciences and Molecular Imaging Innovations Institute, Department of Radiology, New York, NY (United States); Weill Cornell Medicine, Citigroup Biomedical Imaging Center, New York, NY (United States); Kim, Dohyun [Weill Cornell Medicine, Citigroup Biomedical Imaging Center, New York, NY (United States); Babich, John W. [Weill Cornell Medicine, Division of Radiopharmaceutical Sciences and Molecular Imaging Innovations Institute, Department of Radiology, New York, NY (United States); Weill Cornell Medicine, Citigroup Biomedical Imaging Center, New York, NY (United States); Weill Cornell Medicine, Meyer Cancer Center, New York, NY (United States)
2017-04-15
Current clinical imaging of PSMA-positive prostate cancer by positron emission tomography (PET) mainly features {sup 68}Ga-labeled tracers, notably [{sup 68}Ga]Ga-PSMA-HBED-CC. The longer half-life of fluorine-18 offers significant advantages over Ga-68, clinically and logistically. We aimed to develop high-affinity PSMA inhibitors labeled with fluorine-18 as alternative tracers for prostate cancer. Six triazolylphenyl ureas and their alkyne precursors were synthesized from the Glu-urea-Lys PSMA binding moiety. PSMA affinity was determined in a competitive binding assay using LNCaP cells. The [{sup 18}F]triazoles were isolated following a Cu(I)-catalyzed click reaction between the alkynes and [{sup 18}F]fluoroethylazide. The {sup 18}F-labeled compounds were evaluated in nude mice bearing LNCaP tumors and compared to [{sup 68}Ga]Ga-PSMA-HBED-CC and [{sup 18}F]DCFPyL. Biodistribution studies of the two tracers with the highest imaged-derived tumor uptake and highest PSMA affinity were undertaken at 1 h, 2 h and 4 h post-injection (p.i.), and co-administration of PMPA was used to determine whether uptake was PSMA-specific. F-18-labeled triazolylphenyl ureas were prepared with a decay-corrected RCY of 20-40 %, >98 % radiochemical and chemical purity, and specific activity of up to 391 GBq/μmol. PSMA binding (IC{sub 50}) ranged from 3-36 nM. The position of the triazole influenced tumor uptake (3 > 4 > 2), and direct conjugation of the triazole with the phenylurea moiety was preferred to insertion of a spacer group. Image-derived tumor uptake ranged from 6-14 %ID/g at 2 h p.i., the time of maximum tumor uptake; uptake of [{sup 68}Ga]Ga-PSMA-HBED-CC and [{sup 18}F]DCFPyL was 5-6 %ID/g at 1-3 h p.i., the time of maximum tumor uptake. Biodistribution studies of the two most promising compounds gave maximum tumor uptakes of 10.9 ± 1.0 % and 14.3 ± 2.5 %ID/g, respectively, as compared to 6.27 ± 1.44 %ID/g for [{sup 68}Ga]Ga-PSMA-HBED-CC. Six [{sup 18}F
International Nuclear Information System (INIS)
Chen, Liang; Zhao, Xin; Pan, Bingcai; Zhang, Weixian; Hua, Ming; Lv, Lu; Zhang, Weiming
2015-01-01
Highlights: • The nanocomposite HZO-201 was stable under varying solution chemistry. • HZO-201 exhibited preferable phosphate removal over other ubiquitous anions. • Selective sorption mechanism was probed and discussed. • HZO-201 could be regenerated for cyclic use with constant efficiency. - Abstract: In this study, we employed a new nanocomposite adsorbent HZO-201, which featured high stability under varying solution chemistry, for preferable removal of phosphate from synthetic solution and a real effluent. An anion exchange resin (D-201) was employed as the host of HZO-201, where nano-hydrous zirconium oxide (HZO) was encapsulated as the active species. D-201 binds phosphate through nonspecific electrostatic affinity, whereas the loaded HZO nanoparticles capture phosphate through formation of the inner-sphere complexes. Quantitative contribution of both species to phosphate adsorption was predicted based on the double-Langmuir model. Preferable removal of phosphate by HZO-201 was observed in the presence of the competing anions at higher levels (Cl − , NO 3 − , SO 4 2− , HCO 3 − ). Fixed-bed adsorption indicated that the effective volume capacity of a synthetic water (2.0 mg P-PO 4 3− /L) by using HZO-201 was ∼1600 BV in the first run (<0.5 mg P-PO 4 3− /L), comparable to Fe(III)-based nanocomposite HFO-201 (∼1500 BV) and much larger than D-201 (<250 BV). The exhausted HZO-201 can be in situ regenerated by using a binary NaOH–NaCl solution for cyclic runs, whether fed with the synthetic solution or real effluent. In general, HZO-201 is a promising alternative to Fe(III)-based adsorbents for trace phosphate removal from effluent particularly at acidic pH
Translocation of metal phosphate via the phosphate inorganic transport system of Escherichia coli
van Veen, H.W; Abee, T.; Kortstee, G.J J; Konings, W.N; Zehnder, A.J B
1994-01-01
P-i transport via the phosphate inorganic transport system (Pit) of Escherichia coil was studied in natural and artificial membranes. P-i uptake via Pit is dependent on the presence of divalent cations, like Mg2+, Ca2+, Co2+, or Mn2+, which form a soluble, neutral metal phosphate (MeHPO(4)) complex.
[14C]-Sucrose uptake by guard cell protoplasts of pisum sativum, argenteum mutant
International Nuclear Information System (INIS)
Rohrig, K.; Raschke, K.
1991-01-01
Guard cells rely on import for their supply with reduced carbon. The authors tested by silicone oil centrifugation the ability of guard cell protoplasts to accumulated [ 14 C]-sucrose. Uptake rates were corrected after measurement of 14 C-sorbitol and 3 H 2 O spaces. Sucrose uptake followed biphasic kinetics, with a high-affinity component below 1 mM external sucrose (apparent K m 0.8 mM at 25C) and a low-affinity nonsaturable component above. Uptake depended on pH (optimum at pH 5.0). Variations in the concentrations of external KCl, CCCP, and valinomycin indicated that about one-half of the sucrose uptake rate could be related to an electrochemical gradient across the plasmalemma. Total uptake rates measured at 5 mM external sucrose seem to be sufficient to replenish emptied plastids with starch within a few hours
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Kiesewetter, Dale O. [Positron Emission Tomography Radiochemistry Group, NIBIB, Clinical Center, National Institutes of Health, Bethesda, MD 20892 (United States)], E-mail: dk7k@nih.gov; Lang Lixin; Ma Ying; Bhattacharjee, Abesh Kumar [Positron Emission Tomography Radiochemistry Group, NIBIB, Clinical Center, National Institutes of Health, Bethesda, MD 20892 (United States); Gao, Zhan-Guo; Joshi, Bhalchandra V.; Melman, Artem; Castro, Sonia de; Jacobson, Kenneth A. [Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892 (United States)
2009-01-15
Introduction: Bromine-76-radiolabeled analogues of previously reported high-affinity A{sub 3} adenosine receptor (A{sub 3}AR) nucleoside ligands have been prepared as potential radiotracers for positron emission tomography. Methods: The radiosyntheses were accomplished by oxidative radiobromination on the N{sup 6}-benzyl moiety of trimethyltin precursors. Biodistribution studies of the kinetics of uptake were conducted in awake rats. Results: We prepared an agonist ligand {l_brace}[{sup 76}Br](1'S,2'R,3'S,4'R,5'S)-4'-{l_brace}2-chloro-6-[(3-bromophenylmethyl)amino] purin-9-yl{r_brace}-1'-(methylaminocarbonyl)bicyclo[3.1.0]hexane-2',3'-diol (MRS3581){r_brace} in 59% radiochemical yield with a specific activity of 19.5 GBq/{mu}mol and an antagonist ligand {l_brace}[{sup 76}Br](1'R,2'R,3'S,4'R,5'S)-4'-(6-(3-bromobenzylamino) -2-chloro-9H-purin-9-yl)bicyclo[3.1.0]hexane-2',3'-diol (MRS5147){r_brace} in 65% radiochemical yield with a specific activity of 22 GBq/{mu}mol. The resultant products exhibited the expected high affinity (K{sub i}{approx}0.6 nM) and specific binding at the human A{sub 3}AR in vitro. Biodistribution studies in the rat showed uptake in the organs of excretion and metabolism. The antagonist MRS5147 exhibited increasing uptake in testes, an organ that contains significant quantities of A{sub 3}AR, over a 2-h time course, which suggests the presence of a specific A{sub 3}AR retention mechanism. Conclusion: We were able to compare uptake of the [{sup 76}Br]-labeled antagonist MRS5147 to [{sup 76}Br]agonist MRS3581. The antagonist MRS5147 shows increasing uptake in the testes, an A{sub 3}AR-rich tissue, suggesting that this ligand may have promise as a molecular imaging agent.
International Nuclear Information System (INIS)
Maddalena, D.J.; Snowdon, G.M.
1990-01-01
The effects of tumour mass and animal gender on tumour uptake of [ 99m Tc] pertechnetate were examined in balb/c mice bearing an EMT-6 tumour showing high affinity for pertechnetate. The injected dose per gram found in the tumours appears to be inversely related to the tumour mass with good correlation suggesting a high specific uptake. The tumours grown in female mice had greater uptakes and rates of uptake than those grown in the male mice. Studies carried out in animals treated with perchlorate to block active anion transport showed low pertechnetate uptake into the tumours suggesting that the high affinity of 99m TcO 4 - for the tumour was due to a specific 99m TcO 4 - transport mechanism. 15 refs., 3 tabs., 3 figs
Nitrogen and phosphorus uptake in two Idaho (USA) headwater wilderness streams.
Davis, Jeffrey C; Minshall, G Wayne
1999-05-01
Nitrate and phosphate solutions were released into two reaches of two central Idaho streams to determine within- and between-stream variability in uptake lengths, uptake rates, and mass transfer coefficients. Physical and biotic stream characteristics and periphyton nitrate-uptake rates in recirculating chambers were measured to determine their influence on nutrient dynamics. Phosphate uptake length did not differ among the four reaches. There were no within-stream differences in nitrate uptake lengths but they did differ between the two streams. Long nitrate uptake lengths likely were due to instream concentrations above saturation but also may have been influenced by differences in active surface area and algal abundance. Nitrate and phosphate uptake lengths were longer, and uptake rates higher, than most other published values. However, mass transfer coefficients were comparable to measurements in other streams. Mass transfer coefficients may be a better parameter for temporal and spatial comparisons of instream nutrient dynamics, and for determining the underlying causes of variability in uptake length.
International Nuclear Information System (INIS)
Carlson, K.E.; Brandes, S.J.; Pomper, M.G.; Katzenellenbogen, J.A.
1988-01-01
We have investigated the tissue distribution of radioactivity for 0.5-4 h following the i.v. injection of three tritium-labeled progestins in estrogen-primed, immature rats. Whereas [ 3 H]progesterone shows minimal uterine uptake ( 3 H]R 5020 (promegestrone) and [ 3 H]ORG 2058 show highly selective uptake that reaches 4-5% ID/g by 1-3 h. The uterus to non-target tissue activity ratio at 2-4 h is approximately 12-20 for R 5020 and ORG 2058, but less than 2 for progesterone; the uterus to blood activity ratio for R 5020 is also high (approximately 15), but is lower for ORG 2058, possibly due to the accumulation of radiolabeled metabolites in the blood. The uterine uptake is selectively blocked by simultaneous injection of a large dose of unlabeled steroid, indicating that the uptake is mediated by a high affinity, low capacity binding system, presumably the progesterone receptor. Pronounced uptake is also observed by the liver and into fat, but is not receptor-mediated. The highly selective target tissue uptake by the two synthetic steroids, but not by progesterone, indicates that one must have ligands with sufficiently high affinity for the target tissue receptor, as well as low affinity for certain non-receptor binding proteins, in order to obtain adequate contrast between target and non-target tissues in dynamic uptake studies. These guidelines will be important in the development of suitable in vivo imaging agents based on the progesterone receptor. (author)
Directory of Open Access Journals (Sweden)
Daniel Elias
Full Text Available Atrazine, metolachlor, carbaryl, and chlorothalonil are detected in streams throughout the U.S. at concentrations that may have adverse effects on benthic microbes. Sediment samples were exposed to these pesticides to quantify responses of ammonium, nitrate, and phosphate uptake by the benthic microbial community. Control uptake rates of sediments had net remineralization of nitrate (-1.58 NO3 µg gdm⁻¹ h⁻¹, and net assimilation of phosphate (1.34 PO4 µg gdm⁻¹ h⁻¹ and ammonium (0.03 NH4 µg gdm⁻¹ h⁻¹. Metolachlor decreased ammonium and phosphate uptake. Chlorothalonil decreased nitrate remineralization and phosphate uptake. Nitrate, ammonium, and phosphate uptake rates are more pronounced in the presence of these pesticides due to microbial adaptations to toxicants. Our interpretation of pesticide availability based on their water/solid affinities supports no effects for atrazine and carbaryl, decreasing nitrate remineralization, and phosphate assimilation in response to chlorothalonil. Further, decreased ammonium and phosphate uptake in response to metolachlor is likely due to affinity. Because atrazine target autotrophs, and carbaryl synaptic activity, effects on benthic microbes were not hypothesized, consistent with results. Metolachlor and chlorothalonil (non-specific modes of action had significant effects on sediment microbial nutrient dynamics. Thus, pesticides with a higher affinity to sediments and/or broad modes of action are likely to affect sediment microbes' nutrient dynamics than pesticides dissolved in water or specific modes of action. Predicted nutrient uptake rates were calculated at mean and peak concentrations of metolachlor and chlorothalonil in freshwaters using polynomial equations generated in this experiment. We concluded that in natural ecosystems, peak chlorothalonil and metolachlor concentrations could affect phosphate and ammonium by decreasing net assimilation, and nitrate uptake rates by
A phosphate transporter from the mycorrhizal fungus Glomus versiforme.
Harrison, M J; van Buuren, M L
1995-12-07
Vesicular-arbuscular (VA) mycorrhizal fungi form symbiotic associations with the roots of most terrestrial plants, including many agriculturally important crop species. The fungi colonize the cortex of the root to obtain carbon from their plant host, while assisting the plant with the uptake of phosphate and other mineral nutrients from the soil. This association is beneficial to the plant, because phosphate is essential for plant growth and development, especially during growth under nutrient-limiting conditions. Molecular genetic studies of these fungi and their interaction with plants have been limited owing to the obligate symbiotic nature of the VA fungi, so the molecular mechanisms underlying fungal-mediated uptake and translocation of phosphate from the soil to the plant remain unknown. Here we begin to investigate this process by identifying a complementary DNA that encodes a transmembrane phosphate transporter (GvPT) from Glomus versiforme, a VA mycorrhizal fungus. The function of the protein encoded by GvPT was confirmed by complementation of a yeast phosphate transport mutant. Expression of GvPT was localized to the external hyphae of G. versiforme during mycorrhizal associations, these being the initial site of phosphate uptake from the soil.
Emily E. Puckett; Michelle J. Serpiglia; Alyssa M. DeLeon; Stephanie Long; Rakesh Minocha; Lawrence B. Smart
2012-01-01
Studies of arsenate and phosphate uptake by plants in hydroponic and soil systems indicate a common transport mechanism via the phosphate transporters (PHTs) due to structural similarity of the anions. Typically, the presence of phosphate decreases plant uptake and translocation of arsenate in hydroponic solution. This study quantified arsenic (As) uptake related to...
Role of phosphate fertilizers in heavy metal uptake and detoxification of toxic metals.
Gupta, D K; Chatterjee, S; Datta, S; Veer, V; Walther, C
2014-08-01
As a nonrenewable resource, phosphorus (P) is the second most important macronutrient for plant growth and nutrition. Demand of phosphorus application in the agricultural production is increasing fast throughout the globe. The bioavailability of phosphorus is distinctively low due to its slow diffusion and high fixation in soils which make phosphorus a key limiting factor for crop production. Applications of phosphorus-based fertilizers improve the soil fertility and agriculture yield but at the same time concerns over a number of factors that lead to environmental damage need to be addressed properly. Phosphate rock mining leads to reallocation and exposure of several heavy metals and radionuclides in crop fields and water bodies throughout the world. Proper management of phosphorus along with its fertilizers is required that may help the maximum utilization by plants and minimum run-off and wastage. Phosphorus solubilizing bacteria along with the root rhizosphere of plant integrated with root morphological and physiological adaptive strategies need to be explored further for utilization of this extremely valuable nonrenewable resource judiciously. The main objective of this review is to assess the role of phosphorus in fertilizers, their uptake along with other elements and signaling during P starvation. Copyright © 2014 Elsevier Ltd. All rights reserved.
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Nakata, Y; Kusaka, Y; Yajima, H; Segawa, T
1981-12-01
We previously reported that nerve terminals and glial cells lack an active uptake system capable of terminating transmitter action of substance P (SP). In the present study, we demonstrated the existence of an active uptake system for SP carboxy-terminal heptapeptide, (5-11)SP. When the slices from either rat brain or rabbit spinal cord were incubated with (3H)(5-11)SP, the uptake of (5-11)SP into slices was observed. The uptake system has the properties of an active transport mechanism: it is dependent on temperature and sensitive to hypoosmotic treatment and is inhibited by ouabain and dinitrophenol (DNP). In the brain, (5-11)SP was accumulated by means of a high-affinity and a low-affinity uptake system. The Km and the Vmax values for the high-affinity system were 4.20 x 10(-8) M and 7.59 fmol/10 mg wet weight/min, respectively, whereas these values for the low-affinity system were 1.00 x 10(-6) M and 100 fmol/10 mg wet weight/min, respectively. In the spinal cord, there was only one uptake system, with a Km value of 2.16 x 10(-7) M and Vmax value of 26.2 fmol/10 mg wet weight/min. These results suggest that when SP is released from nerve terminals, it is hydrolysed into (5-11)SP before or after acting as a neurotransmitter, which is in turn accumulated into nerve terminals. Therefore, the uptake system may represent a possible mechanism for the inactivation of SP.
Berghe, van den P.V.E; Folmer, D.E.; Malingré, H.E.M.; Beurden, van E.; Klomp, A.E.M.; Sluis, van de B.; Merkx, M.; Berger, R.J.; Klomp, L.W.J.
2007-01-01
High-affinity cellular copper uptake is mediated by the CTR (copper transporter) 1 family of proteins. The highly homologous hCTR (human CTR) 2 protein has been identified, but its function in copper uptake is currently unknown. To characterize the role of hCTR2 in copper homoeostasis,
Rusley, C.; Onstott, T. C.; Lau, M.
2017-12-01
Methane (CH4) is a potent greenhouse gas whose proper budgeting is vital to climate predictions. Recent studies have identified upland Arctic mineral cryosols as consistent CH4 sinks, drawing CH4 from both the atmosphere and underlying anaerobic soil layers. Global atmospheric CH4 uptake is proposed to be mediated by high-affinity methanotrophs based on the detection of the marker gene pmoA (particulate methane monooxygenase beta subunit). However, a lack of pure cultures and scarcity of genomic information have hindered our understanding of their metabolic capabilities and versatility. Together with the missing genetic linkage between its pmoA and 16S ribosomal RNA (rRNA) gene, the factors that control the distribution and magnitude of high-affinity methanotrophy in the Arctic permafrost-affected region have remained elusive. Using 21 metagenomic datasets of surface soils obtained from long-term core incubation experiments,1 this bioinformatics study aimed to reconstruct the draft genome of the Upland Soil Cluster α-proteobacteria (USCα), the high-affinity methanotroph previously detected in the samples,2 and to determine its phylogeny and metabolic requirements. We obtained a genome bin containing the high-affinity form of the USCα-like pmoA gene. The 3.03 Mbp assembly is 91.6% complete with a unique set of single-copy marker genes. The 16S rRNA gene fragment of USCα belongs to the α-proteobacterial family Beijerinckiaceae. Genome annotation indicates possible formaldehyde oxidation via tetrahydromethanopterin-linked C1 transfer pathways, acetate utilization, carbon fixation via the Calvin-Benson-Bassham cycle, and glycogen production. Notably, the key enzymes for formaldehyde assimilation via the serine and ribulose monophosphate pathways are missing. The presence of genes encoding nitrate reductase and hemoglobin suggests adaptation to low O2 under water-logged conditions. Since USCα has versatile carbon metabolisms, it may not be an obligate methanotroph
Affinity labeling and characterization of the active site histidine of glucosephosphate isomerase
International Nuclear Information System (INIS)
Gibson, D.R.; Gracy, R.W.; Hartman, F.C.
1980-01-01
N-bromoacetylethanolamine phosphate was found to act as a specific affinity label for the active center of glucosephosphate isomerase. The inactivation process followed pseudo-first order kinetics, was irreversible, and exhibited rate saturation kinetics with minimal half-lives of inactivation of 4.5 and 6.3 min for the enzyme isolated from human placenta and rabbit muscle, respectively. The pH dependence of the inactivation process closely paralleled the pH dependence of the overall catalytic process with pK/sub a/ values at pH 6.4 and 9.0. The stoichiometry of labeling of either enzyme, as determined with N-bromo[ 14 C 2 ]acetylethanolamine phosphate, was 1 eq of the affinity label/subunit of enzyme. After acid hydrolysis and amino acid analysis of the radioactive affinity-labeled human enzyme, only radioactive 3-carboxymethyl histidine was found. In the case of the rabbit enzyme, the only radioactive derivative obtained was 1-carboxymethyl histidine. Active site tryptic peptides were isolated by solvent extraction, thin layer peptide fingerprinting, and ion exchange chromatography before and after removal of the phosphate from the active site peptide. Amino acid analysis of the labeled peptides from the two species were very similar. Using high sensitivity methods for sequence analysis, the primary structure of the active site was established as Val-Leu-His-Ala-Glu-Asn-Val-Asp (Gly,Thr,Ser) Glu-Ile (Thr-Gly-His-Lys-Glx)-Tyr-Phe. Apparent sequence homology between the catalytic center of glucosephosphate isomerase and triosephosphate isomerase suggest that the two enzymes may have evolved from a common ancestral gene
Selective heavy metals removal from waters by amorphous zirconium phosphate: behavior and mechanism.
Pan, Bingcai; Zhang, Qingrui; Du, Wei; Zhang, Weiming; Pan, Bingjun; Zhang, Qingjian; Xu, Zhengwen; Zhang, Quanxing
2007-07-01
Selective removal of heavy metals from water has been of considerable concern for several decades. In the present study, the amorphous zirconium phosphate (ZrP) was synthesized and characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron micrography (SEM), thermogravimetric analysis (TGA) as well as pH-titration experiments. Uptake of heavy metals including lead, cadmium, and zinc onto ZrP was studied by using a polystyrene sulfonic-acid exchanger D-001 as a reference sorbent and Ca(2+) as a competing cation due to its ubiquity in natural or industrial waters. The results indicated that the uptake of heavy metals onto ZrP is essentially an ion-exchange process and dependent upon solution pH. In comparison with D-001, ZrP exhibited more favorable sorption of heavy metals particularly in terms of high selectivity, as indicated by the distribution coefficients of ZrP even several orders higher than D-001 towards heavy metals when calcium ion coexisted at a high level in solution. The Fourier transform-infrared (FT-IR) spectroscopic investigation indicated that the uptake of calcium, cadmium, and zinc ions onto ZrP is only driven by the electrostatic interaction, while that of lead ion is possibly dependent upon the inner-sphere complex formation with ZrP. XPS results further elucidated that ZrP displays different sorption affinity towards heavy metals in the same order as selectivity sequence of Pb(2+)>Zn(2+) approximately Cd(2+)>Ca(2+), which can be explained by hard and soft acids and bases (HASB) theory. Moreover, uptake of heavy metals onto ZrP approached to equilibrium quickly and the used ZrP could be readily regenerated for reuse by the dilute HCl solution. Thus, all the results suggest that amorphous ZrP has excellent potential as a sorption material for water treatment.
Adsorption and desorption of phosphate on limestone in experiments simulating seawater intrusion
The absorption and desorption of phosphorus on a large block of limestone was investigated using deionized water (DIW) and seawater. The limestone had a high affinity to adsorb phosphorus in DIW. Phosphate adsorption was significantly less in seawater, and more phosphorus was desorbed in the seawate...
Diselenolane-mediated cellular uptake.
Chuard, Nicolas; Poblador-Bahamonde, Amalia I; Zong, Lili; Bartolami, Eline; Hildebrandt, Jana; Weigand, Wolfgang; Sakai, Naomi; Matile, Stefan
2018-02-21
The emerging power of thiol-mediated uptake with strained disulfides called for a move from sulfur to selenium. We report that according to results with fluorescent model substrates, cellular uptake with 1,2-diselenolanes exceeds uptake with 1,2-dithiolanes and epidithiodiketopiperazines with regard to efficiency as well as intracellular localization. The diselenide analog of lipoic acid performs best. This 1,2-diselenolane delivers fluorophores efficiently to the cytosol of HeLa Kyoto cells, without detectable endosomal capture as with 1,2-dithiolanes or dominant escape into the nucleus as with epidithiodiketopiperazines. Diselenolane-mediated cytosolic delivery is non-toxic (MTT assay), sensitive to temperature but insensitive to inhibitors of endocytosis (chlorpromazine, methyl-β-cyclodextrin, wortmannin, cytochalasin B) and conventional thiol-mediated uptake (Ellman's reagent), and to serum. Selenophilicity, the extreme CSeSeC dihedral angle of 0° and the high but different acidity of primary and secondary selenols might all contribute to uptake. Thiol-exchange affinity chromatography is introduced as operational mimic of thiol-mediated uptake that provides, in combination with rate enhancement of DTT oxidation, direct experimental evidence for existence and nature of the involved selenosulfides.
31P NMR study of the interaction of inorganic phosphate with bovine copper-zinc superoxide dismutase
International Nuclear Information System (INIS)
de Freitas, D.M.; Luchinat, C.; Banci, L.; Bertini, I.; Valentine, J.S.
1987-01-01
Paramagnetic effect of 31 P phosphate resonances caused by Cu(II) ions in native and phenylglyoxal-modified bovine Cu,Zn-superoxide dismutase have been used to monitor the interaction of phosphate with these proteins. T 2 values are found to be 70 times smaller than T 1 , indicating that some mechanisms, as yet undefined, contribute to the line width. Using T 1 measurements, it was determined that the affinity constants for phosphate binding to the native protein are 20 +/- 4 and 34 +/- 3 M -1 at pH 8.0 and 7.0 respectively, and that the Cu(II)-phosphate distance 5.3 A. At pH 6.3, two binding sites are observed, one at a distance >7 A with an affinity constant >100 M -1 and another at approximately 5 A with an affinity constant of 10 M -1 . Modification of the protein with phenylglyoxal causes the affinity of phosphate for the same sites to decrease by a factor of 3 at pH 6.3. These results indicate that phosphate does not bind directly to Cu(II) but to a site close by. It was concluded that the site of phosphate binding is Arg-141, which in known from X-ray structural evidence to be located approximately 5 Angstrom form the copper center. 26 references, 4 figures
International Nuclear Information System (INIS)
Garayoa, Elisa Garcia-; Allemann-Tannahill, Lesley; Blaeuenstein, Peter; Willmann, Martine; Carrel-Remy, Nathalie; Tourwe, Dirk; Iterbeke, Koen; Conrath, Peter; Schubiger, P. August
2001-01-01
The potential utility of neurotensin (NT) in cancer diagnosis and therapy is limited by its rapid degradation. New stabilized analogues were synthesized, labeled with [ 99m Tc] and screened in vitro and in vivo. High affinity and rapid internalization were obtained in binding assays. Despite their longer human plasma half-lives, a rapid degradation was observed with low concentrations as used in biodistribution tests. The tumor uptake rates were rather low but tumor/blood ratios increased according to the stability raise
Energy Technology Data Exchange (ETDEWEB)
Garayoa, Elisa Garcia-; Allemann-Tannahill, Lesley; Blaeuenstein, Peter; Willmann, Martine; Carrel-Remy, Nathalie; Tourwe, Dirk; Iterbeke, Koen; Conrath, Peter; Schubiger, P. August E-mail: schubiger@psi.ch
2001-01-01
The potential utility of neurotensin (NT) in cancer diagnosis and therapy is limited by its rapid degradation. New stabilized analogues were synthesized, labeled with [{sup 99m}Tc] and screened in vitro and in vivo. High affinity and rapid internalization were obtained in binding assays. Despite their longer human plasma half-lives, a rapid degradation was observed with low concentrations as used in biodistribution tests. The tumor uptake rates were rather low but tumor/blood ratios increased according to the stability raise.
Quantifying high-affinity binding of hydrophobic ligands by isothermal titration calorimetry.
Krainer, Georg; Broecker, Jana; Vargas, Carolyn; Fanghänel, Jörg; Keller, Sandro
2012-12-18
A fast and reliable quantification of the binding thermodynamics of hydrophobic high-affinity ligands employing a new calorimetric competition experiment is described. Although isothermal titration calorimetry is the method of choice for a quantitative characterization of intermolecular interactions in solution, a reliable determination of a dissociation constant (K(D)) is typically limited to the range 100 μM > K(D) > 1 nM. Interactions displaying higher or lower K(D) values can be assessed indirectly, provided that a suitable competing ligand is available whose K(D) falls within the directly accessible affinity window. This established displacement assay, however, requires the high-affinity ligand to be soluble at high concentrations in aqueous buffer and, consequently, poses serious problems in the study of protein binding involving small-molecule ligands dissolved in organic solvents--a familiar case in many drug-discovery projects relying on compound libraries. The calorimetric competition assay introduced here overcomes this limitation, thus allowing for a detailed thermodynamic description of high-affinity receptor-ligand interactions involving poorly water-soluble compounds. Based on a single titration of receptor into a dilute mixture of the two competing ligands, this competition assay provides accurate and precise values for the dissociation constants and binding enthalpies of both high- and moderate-affinity ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation and high-affinity protein-inhibitor interactions, and explore its potential and limitations with the aid of simulations and statistical analyses.
Affinity of 169Yb, 67Ga and 111In for malignant tumor, (1)
International Nuclear Information System (INIS)
Ando, Itsuko
1975-01-01
The tumor affinity of 169 Yb-citrate, 67 Ga-citrate and 111 In-citrate was examined by using Yoshida sarcoma-bearing rats, and the affinity of these compounds for inflammation was also tested using rats with inflammation induced by croton oil injection. In this investigation there was no great difference in uptake by the tumor tissue of these compounds, but a great difference was observed in the retention value of the blood and uptake rate in the bone. 169 Yb-citrate was cleared rapidly from the blood and was taken mostly into the bone. So the retention values in the soft tissues became very small. On the other hand, 111 In-citrate was slowly and only slightly taken into the bone from the blood, so the retention values in the soft tissue remained relatively high. 67 Ga-citrate showed the intermediate value between the bone uptake rate of 169 Yb-citrate and that of 111 In-citrate. In the following experiments, 169 Yb-citrate and 67 Ga-citrate were compared in four strains: Yoshida sarcoma, Walker carcinosarcoma 256, Sarcoma 180, and Ehrlich tumor. The uptake rate of 169 Yb in tumor tissue was much larger than that of 67 Ga in Ehrlich tumor-bearing mice, but the value of 169 Yb was slightly smaller than those of 67 Ga in Yoshida sarcoma-bearing rats, Walker carcinosarcoma 256-bearing rats and Sarcoma 180-bearing mice. Tumor to organ ratios of 169 Yb, which were most important for tumor scanning, were much larger than those of 67 Ga in all four strains except tumor to bone ratios of 169 Yb. From the above-described facts, it was shown that 169 Yb-citrate had a stronger tumor affinity than 67 Ga-citrate and that the tumor affinity of 169 Yb-citrate was similar in these four strains of tumor bearing animals. These three compounds had a relatively strong affinity with the inflammatory tissue. (auth.)
Tassinary, João Alberto Fioravante; Lunardelli, Adroaldo; Basso, Bruno de Souza; Dias, Henrique Bregolin; Catarina, Anderson Velasque; Stülp, Simone; Haute, Gabriela Viegas; Martha, Bianca Andrade; Melo, Denizar Alberto da Silva; Nunes, Fernanda Bordignon; Donadio, Márcio Vinícius Fagundes; Oliveira, Jarbas Rodrigues de
2018-03-01
The present study aimed to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on pre-osteoblast mineralization using in vitro bioassays. Pre-osteoblastic MC3T3-E1 cells were exposed to LIPUS at 1 MHz frequency, 0.2 W/cm 2 intensity and 20% duty cycle for 30 min. The analyses were carried out up to 336 h (14 days) after exposure. The concentration of collagen, phosphate, alkaline phosphatase, calcium and transforming growth factor beta 1 (TGF-β1) in cell supernatant and the presence of calcium deposits in the cells were analyzed. Our results showed that LIPUS promotes mineralized nodules formation. Collagen, phosphate, and calcium levels were decreased in cell supernatant at 192 h after LIPUS exposure. However, alkaline phosphatase and TGF-β1 concentrations remained unchanged. Therapeutic pulsed ultrasound is capable of stimulating differentiation and mineralization of pre-osteoblastic MC3T3-E1 cells by calcium and phosphate uptake with consequent hydroxyapatite formation. Copyright © 2017 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Deng, Lin, E-mail: denglinlyn@126.com; Shi, Zhou, E-mail: 369329062@qq.com
2015-07-15
Highlights: • Kaolin clay was coalesced with Mg–Al hydrotalcite to form composite adsorbent (MKC). • MKC was synthesized through modified co-precipitation method. • MKC gave high adsorption of phosphate over a wide pH range of 2.5–9.5. • MKC is an economical and environmentally friendly adsorbent for phosphate removal and recycling. - Abstract: The mesoporous modified kaolin clay (MKC) was synthesized by loading Mg–Al hydrotalcite onto kaolin clay through coprecipitation method and applied for adsorption of phosphate from aqueous solution. Several techniques, including Brunauer–Emmett–Teller (BET), thermal analysis (TG–DTA), and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the adsorbents. The effects of adsorbent dosage, solution pH, initial phosphate concentration, contact time, temperature, and coexistent anions on phosphate adsorption have been investigated. MKC exhibited a strong uptake affinity to phosphate in a wide pH range of 2.5–9.5, with the maximum adsorptive removal of 98.03%, at adsorbent dosage of 0.2 g/50 mL, pH 7.5, and initial phosphate concentration 25 mg L{sup −1}. The adsorption kinetics followed the pseudo-second-order kinetic model. The Langmuir isothermal model well described the adsorption isotherm data, showing a maximum adsorption capacity for phosphate up to 11.92 mg g{sup −1} at 298 K. The obtained thermodynamic parameters revealed that the adsorption of phosphate onto MKC was an exothermic and spontaneous process. Coexistent chloride, nitrate, and sulfate ions displayed an adverse effect on phosphate adsorption following the order of SO{sub 4}{sup 2−} > NO{sub 3}{sup −} > Cl{sup −}. A mechanism of adsorption that involved (i) electrostatic attraction of hydroxyl groups of the adsorbent with negatively charged phosphate ions, and (ii) anion exchange of NO{sub 3}{sup −} ions that were associated with the surface or interlayer of the adsorbent with anionic phosphate ions in
International Nuclear Information System (INIS)
Deng, Lin; Shi, Zhou
2015-01-01
Highlights: • Kaolin clay was coalesced with Mg–Al hydrotalcite to form composite adsorbent (MKC). • MKC was synthesized through modified co-precipitation method. • MKC gave high adsorption of phosphate over a wide pH range of 2.5–9.5. • MKC is an economical and environmentally friendly adsorbent for phosphate removal and recycling. - Abstract: The mesoporous modified kaolin clay (MKC) was synthesized by loading Mg–Al hydrotalcite onto kaolin clay through coprecipitation method and applied for adsorption of phosphate from aqueous solution. Several techniques, including Brunauer–Emmett–Teller (BET), thermal analysis (TG–DTA), and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the adsorbents. The effects of adsorbent dosage, solution pH, initial phosphate concentration, contact time, temperature, and coexistent anions on phosphate adsorption have been investigated. MKC exhibited a strong uptake affinity to phosphate in a wide pH range of 2.5–9.5, with the maximum adsorptive removal of 98.03%, at adsorbent dosage of 0.2 g/50 mL, pH 7.5, and initial phosphate concentration 25 mg L −1 . The adsorption kinetics followed the pseudo-second-order kinetic model. The Langmuir isothermal model well described the adsorption isotherm data, showing a maximum adsorption capacity for phosphate up to 11.92 mg g −1 at 298 K. The obtained thermodynamic parameters revealed that the adsorption of phosphate onto MKC was an exothermic and spontaneous process. Coexistent chloride, nitrate, and sulfate ions displayed an adverse effect on phosphate adsorption following the order of SO 4 2− > NO 3 − > Cl − . A mechanism of adsorption that involved (i) electrostatic attraction of hydroxyl groups of the adsorbent with negatively charged phosphate ions, and (ii) anion exchange of NO 3 − ions that were associated with the surface or interlayer of the adsorbent with anionic phosphate ions in solution, was proposed
Ahamed, Muneer; van Veghel, Daisy; Ullmer, Christoph; Van Laere, Koen; Verbruggen, Alfons; Bormans, Guy M
2016-01-01
The type 2 cannabinoid receptor (CB2) is a member of the endocannabinoid system and is known for its important role in (neuro)inflammation. A PET-imaging agent that allows in vivo visualization of CB2 expression may thus allow quantification of neuroinflammation. In this paper, we report the synthesis, radiosynthesis, biodistribution and in vitro evaluation of a carbon-11 ([ 11 C]MA2) and a fluorine-18 ([ 18 F]MA3) labeled analog of a highly potent N -arylamide oxadiazole CB2 agonist (EC 50 = 0.015 nM). MA2 and MA3 behaved as potent CB2 agonist (EC 50 : 3 nM and 0.1 nM, respectively) and their in vitro binding affinity for h CB2 was found to be 87 nM and 0.8 nM, respectively. Also MA3 (substituted with a fluoro ethyl group) was found to have higher binding affinity and EC 50 values when compared to the originally reported trifluoromethyl analog 12 . [ 11 C]MA2 and [ 18 F]MA3 were successfully synthesized with good radiochemical yield, high radiochemical purity and high specific activity. In mice, both tracers were efficiently cleared from blood and all major organs by the hepatobiliary pathway and importantly these compounds showed high brain uptake. In conclusion, [ 11 C]MA2 and [ 18 F]MA3 are shown to be high potent CB2 agonists with good brain uptake, these favorable characteristics makes them potential PET probes for in vivo imaging of brain CB2 receptors. However, in view of its higher affinity and selectivity, further detailed evaluation of MA3 as a PET tracer for CB2 is warranted.
Liu, Yang; Lai, Yu-Chiang; Hill, Elaine V; Tyteca, Donatienne; Carpentier, Sarah; Ingvaldsen, Ada; Vertommen, Didier; Lantier, Louise; Foretz, Marc; Dequiedt, Franck; Courtoy, Pierre J; Erneux, Christophe; Viollet, Benoît; Shepherd, Peter R; Tavaré, Jeremy M; Jensen, Jørgen; Rider, Mark H
2013-10-15
PIKfyve (FYVE domain-containing phosphatidylinositol 3-phosphate 5-kinase), the lipid kinase that phosphorylates PtdIns3P to PtdIns(3,5)P2, has been implicated in insulin-stimulated glucose uptake. We investigated whether PIKfyve could also be involved in contraction/AMPK (AMP-activated protein kinase)-stimulated glucose uptake in skeletal muscle. Incubation of rat epitrochlearis muscles with YM201636, a selective PIKfyve inhibitor, reduced contraction- and AICAriboside (5-amino-4-imidazolecarboxamide riboside)-stimulated glucose uptake. Consistently, PIKfyve knockdown in C2C12 myotubes reduced AICAriboside-stimulated glucose transport. Furthermore, muscle contraction increased PtdIns(3,5)P2 levels and PIKfyve phosphorylation. AMPK phosphorylated PIKfyve at Ser307 both in vitro and in intact cells. Following subcellular fractionation, PIKfyve recovery in a crude intracellular membrane fraction was increased in contracting versus resting muscles. Also in opossum kidney cells, wild-type, but not S307A mutant, PIKfyve was recruited to endosomal vesicles in response to AMPK activation. We propose that PIKfyve activity is required for the stimulation of skeletal muscle glucose uptake by contraction/AMPK activation. PIKfyve is a new AMPK substrate whose phosphorylation at Ser307 could promote PIKfyve translocation to endosomes for PtdIns(3,5)P2 synthesis to facilitate GLUT4 (glucose transporter 4) translocation.
International Nuclear Information System (INIS)
Trottman, C.H.; Rao, K.S.P.; Morrow, W.; Uzodinma, J.E.; Desaiah, D.
1985-01-01
In vitro effects of toxaphene on Ca 2+ -ATPase activity and 45 Ca 2+ -uptake were studied in mitochondrial fractions of heart, kidney and liver tissues of rat. Mitochondrial fractions were prepared by the conventional centrifugation method. Ca 2+ -ATPase activity was determined by measuring the inorganic phosphate liberated during ATP hydrolysis. Toxaphene inhibited Ca 2+ -ATPase in a concentration dependent manner in all the three tissues. Substrate activation kinetics, with heart, kidney and liver tissue fractions, revealed that toxaphene inhibited Ca 2+ -ATPase activity non-competetively by decreasing the maximum velocity of the enzyme without affecting the enzyme-substrate affinity. Toxaphene also inhibited mitochondrial 45 Ca 2+ -uptake in the three selected tissues in a concentration dependent manner. These results indicate that toxaphene is an inhibitor of mitochondrial Ca 2+ -ATPase and calcium transport in heart, kidney and liver tissues of rat. 19 references, 5 figures
International Nuclear Information System (INIS)
Pandey, Renu
2006-01-01
A nutrient culture experiment was conducted with cereal species viz., wheat (Triticum aestivum L.) cv. PBW-343), rye (Secale cereale L cv. R-308) and triticale (Triticale octoploide L. cv. DT-46), a hybrid of wheat and rye, to examine the genetic variation in root-exuded acid phosphatase (ACPase) activity and kinetics of 32 Pi-uptake under P deficient condition. The ACPase activity was assayed in the extract (intra-) and on surface (extra-cellular) or root, using p-nitrophenyl phosphate as substrate. Significantly higher ACPase activity was observed in wheat followed by rye and triticale both on the root surface and in root extract. In general, root surface ACPase activity was 2.2-fold higher than that in root extract. A strong correlation (r 2 = 0.87**) between extra and intra-cellular ACPase activity was observed. In terms of kinetic parameters, it was observed that 32 Pi uptake and I max values were significantly higher in rye while C min and K m were lowest compared to wheat and triticale. The dry weights of shoot, root and total plant were significantly higher in rye compared to wheat and triticale. Rye also had higher amount of total plant P content The superiority of rye over wheat and triticale in P uptake was observed mainly due to efficient Pi-uptake system, which needs further studies to ascertain the enhancement of Pi-induced high-affinity P transporter in these cereals. (author)
Comparison between Arabidopsis and Rice for Main Pathways of K(+) and Na(+) Uptake by Roots.
Nieves-Cordones, Manuel; Martínez, Vicente; Benito, Begoña; Rubio, Francisco
2016-01-01
K(+) is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K(+) in the soil solution are widely variable, K(+) nutrition is secured by uptake systems that exhibit different affinities for K(+). Two main systems have been described for root K(+) uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K(+) uptake, although they only seem to operate when K(+) is not limiting. The use of knock-out lines has allowed demonstrating their role in root K(+) uptake in Arabidopsis and rice. Plant adaptation to the different K(+) supplies relies on the finely tuned regulation of these systems. Low K(+)-induced transcriptional up-regulation of the genes encoding HAK5-like transporters occurs through a signal cascade that includes changes in the membrane potential of root cells and increases in ethylene and reactive oxygen species concentrations. Activation of AKT1 channels occurs through phosphorylation by the CIPK23/CBL1 complex. Recently, activation of the Arabidopsis HAK5 by the same complex has been reported, pointing to CIPK23/CBL as a central regulator of the plant's adaptation to low K(+). Na(+) is not an essential plant nutrient but it may be beneficial for some plants. At low concentrations, Na(+) improves growth, especially under K(+) deficiency. Thus, high-affinity Na(+) uptake systems have been described that belong to the HKT and HAK families of transporters. At high concentrations, typical of saline environments, Na(+) accumulates in plant tissues at high concentrations, producing alterations that include toxicity, water deficit and K(+) deficiency. Data concerning pathways for Na(+) uptake into roots under saline conditions are still scarce, although several possibilities have been proposed. The apoplast is a significant pathway for Na(+) uptake in rice grown under salinity
Comparison between Arabidopsis and Rice for Main Pathways of K+ and Na+ Uptake by Roots
Nieves-Cordones, Manuel; Martínez, Vicente; Benito, Begoña; Rubio, Francisco
2016-01-01
K+ is an essential macronutrient for plants. It is acquired by specific uptake systems located in roots. Although the concentrations of K+ in the soil solution are widely variable, K+ nutrition is secured by uptake systems that exhibit different affinities for K+. Two main systems have been described for root K+ uptake in several species: the high-affinity HAK5-like transporter and the inward-rectifier AKT1-like channel. Other unidentified systems may be also involved in root K+ uptake, although they only seem to operate when K+ is not limiting. The use of knock-out lines has allowed demonstrating their role in root K+ uptake in Arabidopsis and rice. Plant adaptation to the different K+ supplies relies on the finely tuned regulation of these systems. Low K+-induced transcriptional up-regulation of the genes encoding HAK5-like transporters occurs through a signal cascade that includes changes in the membrane potential of root cells and increases in ethylene and reactive oxygen species concentrations. Activation of AKT1 channels occurs through phosphorylation by the CIPK23/CBL1 complex. Recently, activation of the Arabidopsis HAK5 by the same complex has been reported, pointing to CIPK23/CBL as a central regulator of the plant’s adaptation to low K+. Na+ is not an essential plant nutrient but it may be beneficial for some plants. At low concentrations, Na+ improves growth, especially under K+ deficiency. Thus, high-affinity Na+ uptake systems have been described that belong to the HKT and HAK families of transporters. At high concentrations, typical of saline environments, Na+ accumulates in plant tissues at high concentrations, producing alterations that include toxicity, water deficit and K+ deficiency. Data concerning pathways for Na+ uptake into roots under saline conditions are still scarce, although several possibilities have been proposed. The apoplast is a significant pathway for Na+ uptake in rice grown under salinity conditions, but in other plant species
High affinity hemoglobin and Parkinson's disease.
Graham, Jeffrey; Hobson, Douglas; Ponnampalam, Arjuna
2014-12-01
Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra (SN) region of the midbrain. Oxidative damage in this region has been shown to play an important role in the pathogenesis of this disease. Human neurons have been discovered to contain hemoglobin, with an increased concentration seen in the neurons of the SN. High affinity hemoglobin is a clinical entity resulting from mutations that create a functional increase in the binding of hemoglobin to oxygen and an inability to efficiently unload it to tissues. This can result in a number of metabolic compensatory changes, including an elevation in circulating hemoglobin and an increase in the molecule 2,3-diphosphoglycerate (2,3-DPG). Population based studies have revealed that patients with PD have elevated hemoglobin as well as 2,3-DPG levels. Based on these observations, we hypothesize that the oxidative damage seen in PD is related to an underlying high affinity hemoglobin subtype. Copyright © 2014 Elsevier Ltd. All rights reserved.
DEFF Research Database (Denmark)
Prabakaran, Thaneas; Nielsen, Rikke Skovgaard; Satchell, Simon C
2012-01-01
endothelial cells, in order to clarify if the recombinant enzyme is targeted to the lysosomes via the universal mannose 6-phosphate receptor (M6PR) and possibly other receptors. Immunohistochemical localization of infused recombinant α-Gal A in a renal biopsy from a classic Fabry disease patient showed...... that recombinant protein localize in the endothelial cells of the kidney. Affinity purification studies using α-Gal A resins identified M6PR and sortilin as α-Gal A receptors in cultured glomerular endothelial cells. Immunohistochemical analyses of normal human kidney with anti-sortilin and anti-M6PR showed...... that sortilin and M6PR were expressed in the endothelium of smaller and larger vessels. Uptake studies in cultured glomerular endothelial cells of α-Gal A labeled with fluorescence and (125)I showed by inhibition with RAP and M6P that sortilin and M6PR mediated uptake of α-Gal A. Biacore studies revealed that α...
Directory of Open Access Journals (Sweden)
Johan Nilvebrant
Full Text Available The epidermal growth factor receptor 2, ERBB2, is a well-validated target for cancer diagnostics and therapy. Recent studies suggest that the over-expression of this receptor in various cancers might also be exploited for antibody-based payload delivery, e.g. antibody drug conjugates. In such strategies, the full-length antibody format is probably not required for therapeutic effect and smaller tumor-specific affinity proteins might be an alternative. However, small proteins and peptides generally suffer from fast excretion through the kidneys, and thereby require frequent administration in order to maintain a therapeutic concentration. In an attempt aimed at combining ERBB2-targeting with antibody-like pharmacokinetic properties in a small protein format, we have engineered bispecific ERBB2-binding proteins that are based on a small albumin-binding domain. Phage display selection against ERBB2 was used for identification of a lead candidate, followed by affinity maturation using second-generation libraries. Cell surface display and flow-cytometric sorting allowed stringent selection of top candidates from pools pre-enriched by phage display. Several affinity-matured molecules were shown to bind human ERBB2 with sub-nanomolar affinity while retaining the interaction with human serum albumin. Moreover, parallel selections against ERBB2 in the presence of human serum albumin identified several amino acid substitutions that dramatically modulate the albumin affinity, which could provide a convenient means to control the pharmacokinetics. The new affinity proteins competed for ERBB2-binding with the monoclonal antibody trastuzumab and recognized the native receptor on a human cancer cell line. Hence, high affinity tumor targeting and tunable albumin binding were combined in one small adaptable protein.
Citrate and succinate uptake by potato mitochondria
International Nuclear Information System (INIS)
Jung, D.W.; Laties, G.G.
1979-01-01
Potato mitochondria, in the absence of respiration, have a very low capacity for uptake by exchange with endogenous anions, taking up only 2.4 nanomoles citrate and 2.0 nanomoles succinate per milligram protein. Maximum citrate uptake of over 17 nanomoles per milligram protein occurs in the presence of inorganic phosphate, a dicarboxylic acid, and an external energy source (NADH), conditions where net anion accumulation proceeds, mediated by the interlinking of the inorganic phosphate, dicarboxylate, and tricarboxylate carriers. Maximum succinate uptake in the absence of respiratory inhibitors requires only added inorganic phosphate. Compounds which inhibit respiration (antimycin), the exchange carriers (mersalyl and benzylmalonate), or the establishment of the membrane proton motive force (uncouplers) reduce substrate accumulation. A potent inhibitor of the citrate carrier in animal mitochondria, 1,2,3-benzenetricarboxylic acid, does not inhibit citrate uptake in potato mitochondria. Citrate uptake is reduced by concurrent ADP phosphorylation and this reduction is sensitive to oligomycin. The initiation of state 3 after a 3-minute substrate state results in a reduction of the steady-state of citrate uptake by approximately 50%. Accumulation of succinate initially is inhibited by increasing sucrose concentration in the reaction medium from 50 to 400 millimolar. Limited substrate uptake is one of the factors responsible for the often observed depressed initial state 3 respiration rates in many mitochondrial preparations. Since nonlimiting levels of substrate in the matrix cannot be attained by energy-independent exchange, a dependence on respiration for adequate uptake results. Substrate limitation therefore occurs in the matrix for the period of time needed for energy-dependent accumulation of nonlimiting levels
High-throughput fragment screening by affinity LC-MS.
Duong-Thi, Minh-Dao; Bergström, Maria; Fex, Tomas; Isaksson, Roland; Ohlson, Sten
2013-02-01
Fragment screening, an emerging approach for hit finding in drug discovery, has recently been proven effective by its first approved drug, vemurafenib, for cancer treatment. Techniques such as nuclear magnetic resonance, surface plasmon resonance, and isothemal titration calorimetry, with their own pros and cons, have been employed for screening fragment libraries. As an alternative approach, screening based on high-performance liquid chromatography separation has been developed. In this work, we present weak affinity LC/MS as a method to screen fragments under high-throughput conditions. Affinity-based capillary columns with immobilized thrombin were used to screen a collection of 590 compounds from a fragment library. The collection was divided into 11 mixtures (each containing 35 to 65 fragments) and screened by MS detection. The primary screening was performed in 3500 fragments per day). Thirty hits were defined, which subsequently entered a secondary screening using an active site-blocked thrombin column for confirmation of specificity. One hit showed selective binding to thrombin with an estimated dissociation constant (K (D)) in the 0.1 mM range. This study shows that affinity LC/MS is characterized by high throughput, ease of operation, and low consumption of target and fragments, and therefore it promises to be a valuable method for fragment screening.
Directory of Open Access Journals (Sweden)
Muneer Ahamed
2016-09-01
Full Text Available Abstract The type 2 cannabinoid receptor (CB2 is a member of the endocannabinoid system and is known for its important role in (neuroinflammation. A PET-imaging agent that allows in vivo visualization of CB2 expression may thus allow quantification of neuroinflammation. In this paper, we report the synthesis, radiosynthesis, biodistribution and in vitro evaluation of a carbon-11 ([11C]MA2 and a fluorine-18 ([18F]MA3 labeled analogue of a highly potent N-arylamide oxadiazole CB2 agonist (EC50 = 0.015 nM. MA2 and MA3 behaved as potent CB2 agonist (EC50: 3 nM and 0.1 nM, respectively and their in vitro binding affinity for hCB2 was found to be 87 nM and 0.8 nM, respectively. Also MA3 (substituted with a fluoro ethyl group was found to have higher binding affinity and EC50 values when compared to the originally reported trifluoromethyl analogue 12. [11C]MA2 and [18F]MA3 were successfully synthesized with good radiochemical yield, high radiochemical purity and high specific activity. In mice, both tracers were efficiently cleared from blood and all major organs by the hepatobiliary pathway and importantly these compounds showed high brain uptake. In conclusion, [11C]MA2 and [18F]MA3 are shown to be high potent CB2 agonists with good brain uptake, these favorable characteristics makes them potential PET probes for in vivo imaging of brain CB2 receptors. However in view of its higher affinity and selectivity, further detailed evaluation of MA3 as a PET tracer for CB2 is warranted.
Genotypic differences in phosphate nutrition of rice (Oryza Sativa L.)
International Nuclear Information System (INIS)
Bui Thi Hong Thanh; Zapata, F.; Bowen, G.D.; Kumarasinghe, K.S.
1996-01-01
Phosphate uptake and use by five genotypes of paddy rice were studied at five phosphate levels in pot studies for 49 days. For all five P levels there were marked genotypic differences in shoot growth, plant dry weight, root/shoot ratios, phosphate uptake and translocation, P content of roots and shoots, and phosphorus use efficiency of shoots (PUE, g shoot mg P -1 in shoot). There were significant genotypic differences in root weight (4 P levels) and in uptake/mg root (all P levels). These latter may have resulted from differences in root weight/root length conversion, root hair development or uptake characteristics, factors which were not studied specifically. Differences between genotypes and P levels in the percentage translocation were partly explicable by differences in P uptake/plant (r = 0.72) but especially by differences in root/shoot ratios (r = 0.89). Differences in PUE were largely a factor of P percentage of the tops (r = 0.94) but significant differences between genotypes were shown as a function of % P. Differences in net photosynthesis rates were largely, but not entirely, due to differences in P % of the shoots. Key factors in P uptake and use and genotypic differences are root growth, uptake/mg root, root/shoot ratios and PUE. (author). 9 refs, 2 figs, 3 tabs
Genotypic differences in phosphate nutrition of rice (Oryza Sativa L.)
Energy Technology Data Exchange (ETDEWEB)
Hong Thanh, Bui Thi; Zapata, F [FAO/IAEA Agriculture and Biotechnology Lab., Seibersdorf (Austria). Soils Science Unit; Bowen, G D; Kumarasinghe, K S [Joint FAO/IAEA Div. of Nuclear Techniques in Food and Agriculture, Vienna (Austria). Soil Fertility, Irrigation and Crop Production Section
1996-07-01
Phosphate uptake and use by five genotypes of paddy rice were studied at five phosphate levels in pot studies for 49 days. For all five P levels there were marked genotypic differences in shoot growth, plant dry weight, root/shoot ratios, phosphate uptake and translocation, P content of roots and shoots, and phosphorus use efficiency of shoots (PUE, g shoot mg P{sup -1} in shoot). There were significant genotypic differences in root weight (4 P levels) and in uptake/mg root (all P levels). These latter may have resulted from differences in root weight/root length conversion, root hair development or uptake characteristics, factors which were not studied specifically. Differences between genotypes and P levels in the percentage translocation were partly explicable by differences in P uptake/plant (r = 0.72) but especially by differences in root/shoot ratios (r = 0.89). Differences in PUE were largely a factor of P percentage of the tops (r = 0.94) but significant differences between genotypes were shown as a function of % P. Differences in net photosynthesis rates were largely, but not entirely, due to differences in P % of the shoots. Key factors in P uptake and use and genotypic differences are root growth, uptake/mg root, root/shoot ratios and PUE. (author). 9 refs, 2 figs, 3 tabs.
Energy Technology Data Exchange (ETDEWEB)
Hong Huasheng; Wang Minghua; Huang Xuguang [State Key Laboratory of Marine Environmental Science, Xiamen University/Environmental Science Research Center, Xiamen University, No. 192, Daxue Road, Siming Zone, Xiamen 361005 (China); Wang Dazhi, E-mail: dzwang@xmu.edu.c [State Key Laboratory of Marine Environmental Science, Xiamen University/Environmental Science Research Center, Xiamen University, No. 192, Daxue Road, Siming Zone, Xiamen 361005 (China)
2009-06-15
The influences of macronutrient additions on nickel (Ni) uptake and distribution in the subcellular structures and macromolecular components of the dinoflagellate Prorocentrum donghaiense Lu were examined using a radioisotope tracer method. The results showed that nitrate addition enhanced the uptake of Ni by P. donghaiense, whereas phosphate addition inhibited Ni uptake at high-Ni concentration. Nitrate or phosphate addition significantly affected Ni distribution in the subcellular structures and components. The majority of Ni was found in the soluble substances (>70%) and in the proteins (55.0-79.6%) of the algal cells. Urea reduced the Ni content in the amino acid-carbohydrate but elevated its content in proteins, and shown significantly correlated with the protein content of the algal cells. Thus, nutrient enrichment could influence both metal uptake and its distribution in the subcellular structures and components of the phytoplankton, as well as its subsequent transfer in marine food chains. - Macronutrient additions significantly affected nickel uptake and distribution in the subcellular substructures and components of the dinoflagellate.
International Nuclear Information System (INIS)
Hong Huasheng; Wang Minghua; Huang Xuguang; Wang Dazhi
2009-01-01
The influences of macronutrient additions on nickel (Ni) uptake and distribution in the subcellular structures and macromolecular components of the dinoflagellate Prorocentrum donghaiense Lu were examined using a radioisotope tracer method. The results showed that nitrate addition enhanced the uptake of Ni by P. donghaiense, whereas phosphate addition inhibited Ni uptake at high-Ni concentration. Nitrate or phosphate addition significantly affected Ni distribution in the subcellular structures and components. The majority of Ni was found in the soluble substances (>70%) and in the proteins (55.0-79.6%) of the algal cells. Urea reduced the Ni content in the amino acid-carbohydrate but elevated its content in proteins, and shown significantly correlated with the protein content of the algal cells. Thus, nutrient enrichment could influence both metal uptake and its distribution in the subcellular structures and components of the phytoplankton, as well as its subsequent transfer in marine food chains. - Macronutrient additions significantly affected nickel uptake and distribution in the subcellular substructures and components of the dinoflagellate.
DEFF Research Database (Denmark)
Jensen, Frank B.; Kolind, Rasmus A. H.; Jensen, Natashia S.
2017-01-01
-dependent manner. The initial second order rate constant of the deoxyHb-mediated nitrite reduction showed a strong curvilinear correlation with oxygen affinity among all ectothermic vertebrates, and the relationship also applied to plastic variations of Hb properties via organic phosphates. The relationship...... determines oxygen affinity. In the present study we investigated nitrite reductase activity and O2 affinity in Hbs from ten different vertebrate species under identical conditions to disclose interspecific variations and allow an extended test for a correlation between the rate constant for nitrite reduction...... and O2 affinity. We also tested plastic changes in Hb properties via addition of T-structure-stabilizing organic phosphates (ATP and GTP). The decay in deoxyHb during its reaction with nitrite was exponential-like in ectotherms (Atlantic hagfish, carp, crucian carp, brown trout, rainbow trout, cane toad...
Suchak, Sachin K; Baloyianni, Nicoletta V; Perkinton, Michael S; Williams, Robert J; Meldrum, Brian S; Rattray, Marcus
2003-02-01
The excitatory amino acid transporters (EAAT) removes neurotransmitters glutamate and aspartate from the synaptic cleft. Most CNS glutamate uptake is mediated by EAAT2 into glia, though nerve terminals show evidence for uptake, through an unknown transporter. Reverse-transcriptase PCR identified the expression of EAAT1, EAAT2, EAAT3 and EAAT4 mRNAs in primary cultures of mouse cortical or striatal neurones. We have used synaptosomes and glial plasmalemmal vesicles (GPV) from adult mouse and rat CNS to identify the nerve terminal transporter. Western blotting showed detectable levels of the transporters EAAT1 (GLAST) and EAAT2 (Glt-1) in both synaptosomes and GPVs. Uptake of [3H]D-aspartate or [3H]L-glutamate into these preparations revealed sodium-dependent uptake in GPV and synaptosomes which was inhibited by a range of EAAT blockers: dihydrokainate, serine-o-sulfate, l-trans-2,4-pyrrolidine dicarboxylate (PDC) (+/-)-threo-3-methylglutamate and (2S,4R )-4-methylglutamate. The IC50 values found for these compounds suggested functional expression of the 'glial, transporter, EAAT2 in nerve terminals. Additionally blockade of the majority EAAT2 uptake sites with 100 micro m dihydrokainate, failed to unmask any functional non-EAAT2 uptake sites. The data presented in this study indicate that EAAT2 is the predominant nerve terminal glutamate transporter in the adult rodent CNS.
A mathematical model for investigating the effect of cluster roots on plant nutrient uptake
Zygalakis, K. C.
2012-04-01
Cluster roots are thought to play an important role in mediating nutrient uptake by plants. In this paper we develop a mathematical model for the transport and uptake of phosphate by a single root. Phosphate is assumed to diffuse in the soil fluid phase and can also solubilised due to citrate exudation. Using multiple scale homogenisation techniques we derive an effective model that accounts for the cumulative effect of citrate exudation and phosphate uptake by cluster roots whilst still retaining all the necessary information about the microscale geometry and effects. © 2012 EDP Sciences and Springer.
Taft, William C.; Delorenzo, Robert J.
1984-05-01
Benzodiazepines in micromolar concentrations significantly inhibit depolarization-sensitive Ca2+ uptake in intact nerve-terminal preparations. Benzodiazepine inhibition of Ca2+ uptake is concentration dependent and stereospecific. Micromolar-affinity benzodiazepine receptors have been identified and characterized in brain membrane and shown to be distinct from nanomolar-affinity benzodiazepine receptors. Evidence is presented that micromolar, and not nanomolar, benzodiazepine binding sites mediate benzodiazepine inhibition of Ca2+ uptake. Irreversible binding to micromolar benzodiazepine binding sites also irreversibly blocked depolarization-dependent Ca2+ uptake in synaptosomes, indicating that these compounds may represent a useful marker for identifying the molecular components of Ca2+ channels in brain. Characterization of benzodiazepine inhibition of Ca2+ uptake demonstrates that these drugs function as Ca2+ channel antagonists, because benzodiazepines effectively blocked voltage-sensitive Ca2+ uptake inhibited by Mn2+, Co2+, verapamil, nitrendipine, and nimodipine. These results indicate that micromolar benzodiazepine binding sites regulate voltage-sensitive Ca2+ channels in brain membrane and suggest that some of the neuronal stabilizing effects of micromolar benzodiazepine receptors may be mediated by the regulation of Ca2+ conductance.
Spectroscopic properties of highly Nd-doped lead phosphate glass
Energy Technology Data Exchange (ETDEWEB)
Novais, A.L.F. [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil); Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Guedes, I. [Departamento de Física, Universidade Federal do Ceará, Campus do PICI, Caixa Postal 6030, 60455-760 Fortaleza, CE (Brazil); Vermelho, M.V.D., E-mail: vermelho@fis.ufal.br [Instituto de Física, Universidade Federal de Alagoas, Grupo de Fotônica e Fluidos Complexos, 57072-970 Maceió, AL (Brazil)
2015-11-05
The spectroscopic characteristics of highly Nd{sup 3+}-doped lead phosphate glasses (xNd:Pb{sub 3}(PO{sub 4}){sub 2}) have been investigated. The X-ray spectra show that the matrices are glassy up to 25 wt% of Nd{sup 3+} doping. From the Judd–Ofelt analysis we observe that while the Ω{sub (2)} parameter remains constant indicating that the 4f{sup N} and 4f{sup N−1}5 d{sup 1} configurations are not affected by the Nd{sup 3+} doping, the behavior of both Ω{sub (4)} and Ω{sub (6)} changes for 15 wt% of Nd{sup 3+} doping. The reduction of the Ω{sub (6)} parameter is related to the increase of the covalence bonding between the ligands and the Nd{sup 3+} ions. At this particular concentration, the radiative lifetime has a four-fold enhancement. Such behaviors are likely to be related to a modification in the glass structure for high Nd{sup 3+} concentrations. - Graphical abstract: Highly doped lead-phosphate glass matrix, with nominal concentration of up to 25 wt%, maintain the spectroscopic properties without deterioration. The analysis concerning the point of view of Nd{sup 3+} ions showed that high concentrations only affects the rare earth electronic charge density distribution. - Highlights: • Spectroscopic characterization of Nd{sub 2}O{sub 3} highly doped lead phosphate glasses. • Phosphate glass doped with Nd{sup 3+} for applications in photonic devices. • Judd–Ofelt analysis in phosphate glasses doped with Neodymium.
Structure of Greyhound hemoglobin: origin of high oxygen affinity.
Bhatt, Veer S; Zaldívar-López, Sara; Harris, David R; Couto, C Guillermo; Wang, Peng G; Palmer, Andre F
2011-05-01
This study presents the crystal structure of Greyhound hemoglobin (GrHb) determined to 1.9 Å resolution. GrHb was found to crystallize with an α₁β₁ dimer in the asymmetric unit and belongs to the R2 state. Oxygen-affinity measurements combined with the fact that GrHb crystallizes in the R2 state despite the high-salt conditions used for crystallization strongly indicate that GrHb can serve as a model high-oxygen-affinity hemoglobin (Hb) for higher mammals, especially humans. Structural analysis of GrHb and its comparison with the R2-state of human Hb revealed several regions that can potentially contribute to the high oxygen affinity of GrHb and serve to rationalize the additional stability of the R2-state of GrHb. A previously well studied hydrophobic cluster of bar-headed goose Hb near α119 was also incorporated in the comparison between GrHb and human Hb. Finally, a structural comparison with generic dog Hb and maned wolf Hb was conducted, revealing that in contrast to GrHb these structures belong to the R state of Hb and raising the intriguing possibility of an additional allosteric factor co-purifying with GrHb that can modulate its quaternary structure.
Reconstitution of high-affinity opioid agonist binding in brain membranes
Energy Technology Data Exchange (ETDEWEB)
Remmers, A.E.; Medzihradsky, F. (Univ. of Michigan Medical School, Ann Arbor (United States))
1991-03-15
In synaptosomal membranes from rat brain cortex, the {mu} selective agonist ({sup 3}H)dihydromorphine in the absence of sodium, and the nonselective antagonist ({sup 3}H)naltrexone in the presence of sodium, bound to two populations of opioid receptor sites with K{sub d} values of 0.69 and 8.7 nM for dihydromorphine, and 0.34 and 5.5 nM for naltrexone. The addition of 5 {mu}M guanosine 5{prime}-({gamma}-thio)triphosphate (GTP({gamma}S)) strongly reduced high-affinity agonist but not antagonist binding. Exposure of the membranes to high pH reduced the number of GTP({gamma}-{sup 35}S) binding sites by 90% and low K{sub m}, opioid-sensitive GTPase activity by 95%. In these membranes, high-affinity agonist binding was abolished and modulation of residual binding by GTP({gamma}S) was diminished. Alkali treatment of the glioma cell membranes prior to fusion inhibited most of the low K{sub m} GTPase activity and prevented the reconstitution of agonist binding. The results show that high-affinity opioid agonist binding reflects the ligand-occupied receptor - guanine nucleotide binding protein complex.
Haemoglobin Pierre-Benite--a high affinity variant associated with relative polycythaemia.
Beard, M E; Potter, H C; Spearing, R L; Brennan, S O
2001-12-01
This is the second reported example of Hb Pierre--Benite (beta90 Glu-->Asp). This mutation is associated with increased oxygen affinity and polycythaemia. No instability was found and there was no charge shift detected by cellulose acetate electrophoresis at pH 8.3. The mutation was however, clearly indicated by electrospray ionization mass spectrometry (ESI MS), which showed an abnormal beta chain with a 14 Da decrease in mass. Blood volume studies documented a relative rather than a true polycythaemia and this finding has been reported in at least two other high affinity haemoglobin variants--Hb Heathrow and Hb Rahere. This finding led to delay in diagnosis because high oxygen affinity variants are conventionally considered to cause a true polycythaemia.
On the mechanism of ion exchange in zirconium phosphates
International Nuclear Information System (INIS)
Clearfield, A.; Kalnins, J.M.
1978-01-01
The exchange of transition metal (M 2+ ) ions from manganese through cobalt, nickel, copper to zinc with γ-zirconium phosphate was examined. By using acetate salts the hydrogen ion concentration is kept low enough to achieve high loadings. The fully loaded solids have the composition ZrM(PO 4 ) 2 .4H 2 O. Near quantitative uptakes are achieved at 100 0 C. The interlayer spacings change very little with loading indicating that γ-zirconium phosphate is able to accommodate cations and water molecules without appreciable increase in volume. The copper exchanged phase readily forms an acetylacetonate when shaken with 2,4-pentanedione. (author)
The mechanism of zinc uptake in excised roots and leaf discs of Phaseolus vulgaris L
International Nuclear Information System (INIS)
Van As, J.A.
1991-03-01
The mechanism and nature of zinc uptake was studied with the aid of 65 Zn. Uptake of zinc was also compared to that of potassium and phosphate, which are known to be ATP-dependent. Zinc uptake was characterized by a rapid initial uptake, followed by a slower linear phase. Decreasing the temperature from 25 to 2 deg C resulted in a decrease of only 30% in the rate of zinc uptake. Uptake of zinc was insensitive to DNP - possibly indicating the non-metabolic nature of the uptake process. A possible role for zinc in protein synthesis could not be demonstrated as CHI did not inhibit zinc uptake. Cyanide reduced zinc uptake to almost zero, possibly due to complexation of zinc by cyanide. Light had no effect on the accumulation of Zn, whereas dark incubation reduced potassium uptake substantially. The relative high rate of zinc uptake and the passive nature of the uptake process might be due to the high binding capacity of the free space for zinc ions. Transport of the zinc in the xylem and phloem of intact bean plants, as well as the metabolic dependence of the latter, was also investigated. The bulk of the zinc absorbed by bean plants remained in the roots and stems with only a very small fraction being translocated to shoots. Adsorption was the major uptake mechanism in roots and stems. In contrast to transport in the xylem, zinc was readily transported in the phloem. Loading and unloading of zinc in the phloem was not influenced by low temperature or DNP. Opposed to this, loading of potassium and phosphate was inhibited by DNP, while unloading was inhibited by low temperature. It can therefore be concluded that the uptake and transport of zinc is probably a passive process. 33 figs., 282 refs
Chen, Chung-Ho; Greenawalt, John W.; Lehninger, Albert L.
1974-01-01
Mitochondria isolated from the hepatopancreas of the blue crab Callinectes sapidus show up to 12-fold stimulation of respiration on addition of Ca2+, which is accompanied by Ca2+ accumulation (Ca2+:site = 1.9) and H+ ejection (H+:Ca2+ = 0.85). Sr2+ and Mn2+ are also accumulated; Mg2+ is not. A strongly hypertonic medium (383 mosM), Mg2+, and phosphate are required for maximal Ca2+ uptake. Ca2+ uptake takes precedence over oxidative phosphorylation of ADP for respiratory energy. Once Ca2+ is accumulated by the crab mitochondria, it is stable and only very slowly released, even by uncoupling agents. ATP hydrolysis also supports Ca2+ uptake. Respiration-inhibited crab hepatopancreas mitochondria show both high-affinity and low-affinity Ca2+-binding sites, which are inactive in the presence of uncoupling agents. Crab hepatopancreas mitochondria have an enormous capacity for accumulation of Ca2+, up to 5,500 ng-atoms Ca2+ per mg protein, with an equivalent amount of phosphate. Freshly isolated mitochondria contain very large amounts of Ca2+, Mg2+, phosphate, K+, and Na+; their high Ca2+ content is a reflection of the vary large amount of extra-mitochondrial Ca2+ in the whole tissue. Electron microscopy of crab mitochondria loaded with Ca2+ and phosphate showed large electron-dense deposits, presumably of precipitated calcium phosphate. They consisted of bundles of needle-like crystals, whereas Ca2+-loaded rat liver mitochondria show only amorphous deposits of calcium phosphate under similar conditions. The very pronounced capacity of crab hepatopancreas mitochondria for transport of Ca2+ appears to be adapted to a role in the storage and release of Ca2+ during the molting cycle of this crustacean. PMID:4827906
DEFF Research Database (Denmark)
Roos, Per; Jakobsen, Iver
2008-01-01
Uptake of metals from uranium-rich phosphate rock was studied in Medicago truncatula plants grown in symbiosis with the arbuscular mycorrhizal fungus Glomus intraradices or in the absence of mycorrhizas. Shoot concentrations of uranium and thorium were lower in mycorrhizal than in non-mycorrhizal......-fungus uptake systems. The results support the role of arbuscular mycorrhiza as being an important component in phytostabilization of uranium. This is the first study to report on mycorrhizal effect and the uptake and root-to-shoot transfer of thorium from phosphate rock. (c) 2007 Elsevier Ltd. All rights...
Energy Technology Data Exchange (ETDEWEB)
Pegos, Vanessa R.; Hey, Louis; LaMirande, Jacob; Pfeffer, Rachel; Lipsh, Rosalie; Amitay, Moshe; Gonzalez, Daniel; Elias, Mikael (JCT-Israel); (UMM); (CNRS-UMR)
2017-05-25
Phosphate-binding proteins (PBPs) are key proteins that belong to the bacterial ABC-type phosphate transporters. PBPs are periplasmic (or membrane-anchored) proteins that capture phosphate anions from the environment and release them to the transmembrane transporter. Recent work has suggested that PBPs have evolved for high affinity as well as high selectivity. In particular, a short, unique hydrogen bond between the phosphate anion and an aspartate residue has been shown to be critical for selectivity, yet is not strictly conserved in PBPs. Here, the PBP from
Wintgens, Véronique; Dalmas, Florent; Sébille, Bernard; Amiel, Catherine
2013-10-15
Novel phosphorous-containing β-cyclodextrin (βCD) polymers (CDP) were synthesized easily under "green chemistry" conditions. A simple polycondensation between the hydroxyl groups of βCD and non-toxic sodium trimetaphosphate (STMP) under basic conditions led to soluble, non-reticulated CDPs with molecular weights (Mw) higher than 10(4) g mol(-1), the actual value depending on the NaOH:βCD and STMP:βCD weight ratios. The presence of both βCD and phosphate groups in the polymer allows for strong interactions with amphiphilic probes, such as 1-adamantyl acetic acid, or with divalent cations, such as Ca(2+), whose strengths were characterized by isothermal titration microcalorimetry. The obtained phosphated compounds also display high affinity towards hydroxyapatite (HA), leading to HA nanoparticles that could easily be recovered by CDPs, as demonstrated by transmission electron microscopy and quantitative determination of the total amount of phosphated molecules fixed on HA. Copyright © 2013 Elsevier Ltd. All rights reserved.
Lime and Phosphate Amendment Can Significantly Reduce Uptake of Cd and Pb by Field-Grown Rice
Directory of Open Access Journals (Sweden)
Rongbo Xiao
2017-03-01
Full Text Available Agricultural soils are suffering from increasing heavy metal pollution, among which, paddy soil polluted by heavy metals is frequently reported and has elicited great public concern. In this study, we carried out field experiments on paddy soil around a Pb-Zn mine to study amelioration effects of four soil amendments on uptake of Cd and Pb by rice, and to make recommendations for paddy soil heavy metal remediation, particularly for combined pollution of Cd and Pb. The results showed that all the four treatments can significantly reduce the Cd and Pb content in the late rice grain compared with the early rice, among which, the combination amendment of lime and phosphate had the best remediation effects where rice grain Cd content was reduced by 85% and 61%, respectively, for the late rice and the early rice, and by 30% in the late rice grain for Pb. The high reduction effects under the Ca + P treatment might be attributed to increase of soil pH from 5.5 to 6.7. We also found that influence of the Ca + P treatment on rice production was insignificant, while the available Cd and Pb content in soil was reduced by 16.5% and 11.7%, respectively.
Human-Phosphate-Binding-Protein inhibits HIV-1 gene transcription and replication
Directory of Open Access Journals (Sweden)
Candolfi Ermanno
2011-07-01
Full Text Available Abstract The Human Phosphate-Binding protein (HPBP is a serendipitously discovered lipoprotein that binds phosphate with high affinity. HPBP belongs to the DING protein family, involved in various biological processes like cell cycle regulation. We report that HPBP inhibits HIV-1 gene transcription and replication in T cell line, primary peripherical blood lymphocytes and primary macrophages. We show that HPBP is efficient in naïve and HIV-1 AZT-resistant strains. Our results revealed HPBP as a new and potent anti HIV molecule that inhibits transcription of the virus, which has not yet been targeted by HAART and therefore opens new strategies in the treatment of HIV infection.
Ethanol intake and 3H-serotonin uptake I: A study in Fawn-Hooded rats
International Nuclear Information System (INIS)
Daoust, M.; Compagnon, P.; Legrand, E.; Boucly, P.
1991-01-01
Ethanol intake and synaptosomal 3 H-serotonin uptake were studied in male Fawn-Hooded and Sprague-Dawley rats. Fawn-Hooded rats consumed more alcohol and more water than Sprague-Dawley rats. Plasma alcohol levels of Sprague-Dawley rats were not detectable but were about 5 mg/dl in Fawn-Hooded rats. Ethanol intake increased the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex, but not in thalamus. In Fawn-Hooded rats, serotonin uptake (Vmax) was higher than in Sprague-Dawley rats cortex. Ethanol intake reduced the Vmax of serotonin uptake in Fawn-Hooded rats in hippocampus and cortex. In cortex, the carrier affinity for serotonin was increased in alcoholized Fawn-Hooded rats. These results indicate that synaptosomal 3 H-serotonin uptake is affected by ethanol intake. In Fawn-Hooded rats, high ethanol consumption is associated with high serotonin uptake. In rats presenting high serotonin uptake, alcoholization reduces 3 H-serotonin internalization in synaptosomes, indicating a specific sensitivity to alcohol intake of serotonin uptake system
Controlled synthesized natroalunite microtubes applied for cadmium(II) and phosphate co–removal
Energy Technology Data Exchange (ETDEWEB)
Xu, Huan [School of Physics and Materials Science, Anhui University, Hefei 230601 (China); Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); Zhu, Baisheng [University of Science and Technology of China, Hefei 230026 (China); Ren, Xuemei, E-mail: renxm1985@163.com [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); Shao, Dadong; Tan, Xiaoli; Chen, Changlun [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China)
2016-08-15
Highlights: • Five natroalunite samples with different morphologies were synthesized. • EG: water ratio controls the morphology and adsorption performance of natroalunite. • NMs show the best performance in Cd(II) and phosphate co-uptake. • Phosphate bridges NMs and Cd(II) in co–removal process and enhances Cd(II) uptake. - Abstract: Treatment of wastewater containing several kinds of contaminants poses great challenges, because heavy metal and inorganic anion contaminants possess different fate and transport mechanisms. Individual adsorption of Cd(II)/phosphate on clay or metallic oxides has been extensively investigated, but the mutual effects of these two species in co–existing systems have received little attention. In this study, five natroalunite samples with different morphologies were synthesized by a simple hydrothermal method with appropriate volume ratio of ethylene glycol (EG) to water. The volume ratio of EG to water plays a key role in the formation of natroalunite samples, and dramatically affects their adsorption capacities. The mutual effects of Cd(II) and phosphate on their interaction with natroalunite microtubes (NMs) were investigated by varying experimental conditions, such as pH, temperature and addition sequences. The results demonstrate that highly efficient co–removal of Cd(II) and phosphate can be accomplished using NMs, and the process is strongly dependent on solution pH and temperature via the formation of ternary surface complexes. This study implies that the hydrothermally synthesized NMs can be regarded as a potential promising material for the co–removal of Cd(II) and phosphate from large volumes of aqueous solutions in pollution management.
A modified assay method for determining serotonin uptake in human platelets
International Nuclear Information System (INIS)
Arora, R.C.; Meltzer, H.Y.
1981-01-01
Effects of various experimental conditions on serotonin (5-HT) uptake in human platelets were examined. The experimental design allowed the evaluation of the effect of diffusion and other non-saturable processes on the affinity and maximum activity of the membrane pump for 5-HT uptake. Total 5-HT uptake was determined by incubating platelet-rich plasma (PRP) with increasing concentrations of serotonin at 37 0 C for 4 min. The passive uptake was measured by the addition of various 5-HT concentrations to PRP in buffer at 37 0 C, followed by immediate transfer to an ice-cold water bath. The difference between the total and passive uptake was linear for 6 min. The affinity (Ksub(m)) for active platelet serotonin uptake was 0.45 +- 0.09 μmol/l and maximal rate of uptake (V) was 10.7 +- 2.1 pmol/10 7 platelets/min. The described method provides a convenient and reliable measure of active 5-HT uptake suitable for clinical investigation. The effect of passive diffusion on kinetic parameters is discussed. (Auth.)
International Nuclear Information System (INIS)
Jang, H.D.; Swaisgood, H.E.
1990-01-01
Interaction of calcium with casein submicelles was investigated in CaCl2 and calcium phosphate buffers and with synthetic milk salt solutions using the technique of analytical affinity chromatography. Micelles that had been prepared by size exclusion chromatography with glycerolpropyl controlled-pore glass from fresh raw skim milk that had never been cooled, were dialyzed at room temperature against calcium-free imidazole buffer, pH 6.7. Resulting submicelles were covalently immobilized on succinamidopropyl controlled-pore glass (300-nm pore size). Using 45Ca to monitor the elution retardation, the affinity of free Ca2+ and calcium salt species was determined at temperatures of 20 to 40 degrees C and pH 6.0 to 7.5. Increasing the pH in this range or increasing the temperature strengthened the binding of calcium to submicelles, similar to previous observations with individual caseins. However, the enthalpy change obtained from the temperature dependence was considerably greater than that reported for alpha s1- and beta-caseins. Furthermore, the elution profiles for 45Ca in milk salt solutions were decidedly different from those in CaCl2 or calcium phosphate buffers and the affinities were also greater. For example, at pH 6.7 and 30 degrees C the average dissociation constant for the submicelle-calcium complex is 0.074 mM for CaCl2 and calcium phosphate buffers, vs 0.016 mM for the milk salt solution. The asymmetric frontal boundaries and higher average affinities observed with milk salts may be due to binding of calcium salts with greater affinity in addition to the binding of free Ca2+ in these solutions
Directory of Open Access Journals (Sweden)
Lykke Pedersen
2014-01-01
Full Text Available Antisense oligonucleotides complementary to RNA targets promise generality and ease of drug design. The first systemically administered antisense drug was recently approved for treatment and others are in clinical development. Chemical modifications that increase the hybridization affinity of oligonucleotides are reasoned to confer higher potency, i.e., modified oligonucleotides can be dosed at lower concentrations to achieve the same effect. Surprisingly, shorter and less affine oligonucleotides sometimes display increased potency. To explain this apparent contradiction, increased uptake or decreased propensity to form structures have been suggested as possible mechanisms. Here, we provide an alternative explanation that invokes only the kinetics behind oligonucleotide-mediated cleavage of RNA targets. A model based on the law of mass action predicts, and experiments support, the existence of an optimal binding affinity. Exaggerated affinity, and not length per se, is detrimental to potency. This finding clarifies how to optimally apply high-affinity modifications in the discovery of potent antisense oligonucleotide drugs.
Selenium Uptake and Volatilization by Marine Algae
Luxem, Katja E.; Vriens, Bas; Wagner, Bettina; Behra, Renata; Winkel, Lenny H. E.
2015-04-01
Selenium (Se) is an essential trace nutrient for humans. An estimated one half to one billion people worldwide suffer from Se deficiency, which is due to low concentrations and bioavailability of Se in soils where crops are grown. It has been hypothesized that more than half of the atmospheric Se deposition to soils is derived from the marine system, where microorganisms methylate and volatilize Se. Based on model results from the late 1980s, the atmospheric flux of these biogenic volatile Se compounds is around 9 Gt/year, with two thirds coming from the marine biosphere. Algae, fungi, and bacteria are known to methylate Se. Although algal Se uptake, metabolism, and methylation influence the speciation and bioavailability of Se in the oceans, these processes have not been quantified under environmentally relevant conditions and are likely to differ among organisms. Therefore, we are investigating the uptake and methylation of the two main inorganic Se species (selenate and selenite) by three globally relevant microalgae: Phaeocystis globosa, the coccolithophorid Emiliania huxleyi, and the diatom Thalassiosira oceanica. Selenium uptake and methylation were quantified in a batch experiment, where parallel gas-tight microcosms in a climate chamber were coupled to a gas-trapping system. For E. huxleyi, selenite uptake was strongly dependent on aqueous phosphate concentrations, which agrees with prior evidence that selenite uptake by phosphate transporters is a significant Se source for marine algae. Selenate uptake was much lower than selenite uptake. The most important volatile Se compounds produced were dimethyl selenide, dimethyl diselenide, and dimethyl selenyl sulfide. Production rates of volatile Se species were larger with increasing intracellular Se concentration and in the decline phase of the alga. Similar experiments are being carried out with P. globosa and T. oceanica. Our results indicate that marine algae are important for the global cycling of Se
International Nuclear Information System (INIS)
Xiong, L.M.; Zhou, Z.G.; Feng, G.L.; Lu, R.K.; Fardeau, J.C.
2002-01-01
In an attempt to assess current soil phosphorus status and evaluate the effectiveness of local rock phosphates in subtropical China, nearly 40 representative soil samples from this region were collected and characterized by using 32 P isotope and chemical extraction techniques. Pot experiments, incubation studies and field trials were conducted to investigate the interaction of rock phosphates and water-soluble phosphates as well as the effects of rock phosphate on soil chemical properties in selected soils. Results indicated that these soils were generally low in available phosphorus and high in P-fixing capacity. The soil characteristics dictated that the employed isotope kinetic model was less successful in predicting plant P uptake than the chemical procedures tested. A new chemical extraction method consisting of sodium bicarbonate and ammonium fluoride was proposed to evaluate available P in these Solis. Data on available P generated with the proposed method gave the best prediction of plant uptake amongst all methods compared. In a pot experiment, the combined application of soluble P fertilizer with local rock phosphate significantly enhanced plant growth and increased P uptake. This positive interaction was attributed to the improved soil chemical properties due to the application of low-grade rock phosphates, as demonstrated in incubation studies. These results suggest that rock phosphate-based fertilizers should be good alternative fertilizers for plants in similar acidic soils in southern China. (author)
Directory of Open Access Journals (Sweden)
Fabian König
Full Text Available The monoclonal antibody S9.6 is a widely-used tool to purify, analyse and quantify R-loop structures in cells. A previous study using the surface plasmon resonance technology and a single-chain variable fragment (scFv of S9.6 showed high affinity (0.6 nM for DNA-RNA and also a high affinity (2.7 nM for RNA-RNA hybrids. We used the microscale thermophoresis method allowing surface independent interaction studies and electromobility shift assays to evaluate additional RNA-DNA hybrid sequences and to quantify the binding affinities of the S9.6 antibody with respect to distinct sequences and their GC-content. Our results confirm high affinity binding to previously analysed sequences, but reveals that binding affinities are highly sequence specific. Our study presents R-loop sequences that independent of GC-content and in different sequence variations exhibit either no binding, binding affinities in the micromolar range and as well high affinity binding in the nanomolar range. Our study questions the usefulness of the S9.6 antibody in the quantitative analysis of R-loop sequences in vivo.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Ying [Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032 (China); Key Laboratory of Glycoconjugates Research Ministry of Public Health, Fudan University, Shanghai 200032 (China); Peng, Ye; Bin, Zhichao [Department of Chemistry, Fudan University, Shanghai 200032 (China); Wang, Huijie [Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032 (China); Lu, Haojie, E-mail: luhaojie@fudan.edu.cn [Shanghai Cancer Center and Institutes of Biomedical Sciences, Fudan University, Shanghai 200032 (China); Department of Chemistry, Fudan University, Shanghai 200032 (China); Key Laboratory of Glycoconjugates Research Ministry of Public Health, Fudan University, Shanghai 200032 (China)
2016-08-31
N-linked protein glycosylation is involved in regulation of a wide variety of cellular processes and associated with numerous diseases. Highly specific identification of N-glycome remains a challenge while its biological significance is acknowledged. The relatively low abundance of glycan in complex biological mixtures, lack of basic sites for protonation, and suppression by other highly abundant proteins/peptides lead to the particularly poor detection sensitivity of N-glycans in the MS analysis. Therefore, the highly specific purification procedure becomes a crucial step prior to MS analysis of the N-glycome. Herein, a novel N-glycans enrichment approach based on phosphate derivatization combined with Ti{sup 4+}-SPE (solid phase extraction) was developed. Briefly, in this strategy, N-glycans were chemically labeled with a phospho-group at their reducing ends, such that the Ti{sup 4+}-SPE microspheres were able to capture the phospho-containing glycans. The enrichment method was developed and optimized using model oligosaccharides (maltoheptaose DP7 and sialylated glycan A1) and also glycans from a standard glycoprotein (asialofetuin, ASF). This method experimentally showed high derivatization efficiency (almost 100%), excellent selectivity (analyzing DP7 in the digests of bovine serum albumin at a mass ratio of 1:100), high enriching recovery (90%), good reproducibility (CV<15%) as well as high sensitivity (LOD at fmol level). At last, the proposed method was successfully applied in the profiling of N-glycome in human serum, in which a total of 31 N-glycan masses were identified. - Graphical abstract: A selective enrichment method for the N-glycome is reported. N-glycans were chemically labeled with a phosphate derivatization reagent (AMS), then the phospho-containing glycans were enriched using Ti{sup 4+}-microspheres. - Highlights: • A highly specific N-glycans purification method based on phosphate derivatization combined with Ti{sup 4+}-SPE was developed
Dermal uptake and percutaneous penetration of organophosphate esters in a human skin ex vivo model
DEFF Research Database (Denmark)
Frederiksen, Marie; Stapleton, Heather M; Vorkamp, Katrin
2018-01-01
Organophosphate esters (OPEs) are used as flame retardants, plasticizers, and as hydraulic fluids. They are present in indoor environments in high concentrations compared with other flame retardants, and human exposure is ubiquitous. In this study we provide data for estimating dermal uptake...... through the skin. For tris(isobutyl) phosphate (TIBP), tris(n-butyl) phosphate (TNBP), and tris(methylphenyl) phosphate (TMPP) the mass balance was not stable over time indicating possible degradation during the experimental period of 72 h. The rates at which OPEs permeated through the skin decreased...
Minimalistic Liquid-Assisted Route to Highly Crystalline α-Zirconium Phosphate.
Cheng, Yu; Wang, Xiaodong Tony; Jaenicke, Stephan; Chuah, Gaik-Khuan
2017-08-24
Zirconium phosphates have potential applications in areas of ion exchange, catalysis, photochemistry, and biotechnology. However, synthesis methodologies to form crystalline α-zirconium phosphate (Zr(HPO 4 ) 2 ⋅H 2 O) typically involve the use of excess phosphoric acid, addition of HF or oxalic acid and long reflux times or hydrothermal conditions. A minimalistic sustainable route to its synthesis has been developed by using only zirconium oxychloride and concentrated phosphoric acid to form highly crystalline α-zirconium phosphate within hours. The morphology can be changed from platelets to rod-shaped particles by fluoride addition. By varying the temperature and time, α-zirconium phosphate with particle sizes from nanometers to microns can be obtained. Key features of this minimal solvent synthesis are the excellent yields obtained with high atom economy under mild conditions and ease of scalability. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Strange, J.R.; Williamson, G.D.; Fletcher, D.J.
1975-01-01
A study of the Flat Creek Embayment of Lake Sidney Lanier near Gainesville, Georgia revealed three genera of algae, Chlorococcum, Fragillaria and Nostoc, to be prominent in this eutrophic region of the lake. The algae was grown in phosphate-rich media and subsequently labelled with P-32. All species incorporated luxury amounts of phosphorus as determined by the uptake of P-32. The results indicate that the P-32 uptake is proportional to the surface-per-volume ratio. The higher surface-per-volume ratio resulted in greater uptake of P-32
The role of CH/π interactions in the high affinity binding of streptavidin and biotin.
Ozawa, Motoyasu; Ozawa, Tomonaga; Nishio, Motohiro; Ueda, Kazuyoshi
2017-08-01
The streptavidin-biotin complex has an extraordinarily high affinity (Ka: 10 15 mol -1 ) and contains one of the strongest non-covalent interactions known. This strong interaction is widely used in biological tools, including for affinity tags, detection, and immobilization of proteins. Although hydrogen bond networks and hydrophobic interactions have been proposed to explain this high affinity, the reasons for it remain poorly understood. Inspired by the deceased affinity of biotin observed for point mutations of streptavidin at tryptophan residues, we hypothesized that a CH/π interaction may also contribute to the strong interaction between streptavidin and biotin. CH/π interactions were explored and analyzed at the biotin-binding site and at the interface of the subunits by the fragment molecular orbital method (FMO) and extended applications: PIEDA and FMO4. The results show that CH/π interactions are involved in the high affinity for biotin at the binding site of streptavidin. We further suggest that the involvement of CH/π interactions at the subunit interfaces and an extended CH/π network play more critical roles in determining the high affinity, rather than involvement at the binding site. Copyright © 2017 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Escandon, E.; Chao, M.V.
1990-01-01
In order to study regulation of the nerve growth factor (NGF) receptor during embryogenesis in chick brain, we have used affinity crosslinking of tissues with 125 I-NGF. NGF interacts with high- and low-affinity receptors; high-affinity receptors are required for the majority of NGF's actions. Most measurements of receptor levels do not distinguish between high- and low-affinity forms of the receptor. We have used the lipophilic crosslinking agent HSAB to identify the high-affinity, functional receptor during development of the chicken central nervous system. A peak of expression during Embryonic Days 5-10 was detected in all regions of the chicken central nervous system, but, shortly after birth, only the cerebellar region displays significant levels of NGF receptor protein. The time course of expression confirms the dramatic regulation of the NGF receptor gene during defined embryonic periods. The detection of high-affinity NGF receptors in brain and neural retina provides strong evidence that NGF is involved in essential ontogenetic events in the development of the chicken central nervous system
High affinity calmodulin target sequence in the signalling molecule PI 3-kinase
DEFF Research Database (Denmark)
Fischer, R; Julsgart, J; Berchtold, M W
1998-01-01
M-binding peptide derived from the p110gamma isoform interacts with CaM in a calcium-dependent way. Using gel shift analysis and fluorescence spectrophotometry we discovered that the peptide forms a high affinity complex with CaM. Titration experiments using dansylated CaM gave an affinity constant of 5 n...
Effect of phosphate supplementation on oxygen delivery at high altitude
Jain, S. C.; Singh, M. V.; Rawal, S. B.; Sharma, V. M.; Divekar, H. M.; Tyagi, A. K.; Panwar, M. R.; Swamy, Y. V.
1987-09-01
In the present communication, effect of low doses of phosphate supplementation on short-term high altitude adaptation has been examined. Studies were carried out in 36 healthy, male, sea-level residents divided in a double blind fashion into drug and placebo treated groups. 3.2 mmol of phosphate were given orally to each subject of the drug treated group once a day for 4 days on arrival at an altitude of 3,500 m. Sequential studies were done in the subjects in both groups on the 3rd, 7th, 14th and 21st day of their altitude stay. Haemoglobin, haematocrit, erythrocyte and reticulocyte counts increased to the similar extent in both groups. Blood pH, pO2 and adenosine tri-phosphate (ATP) did not differ between the two groups. On 3rd day of the altitude stay, inorganic phosphate and 2,3-diphosphoglycerate (2,3 DPG) levels in the drug treated group increased significantly as compared to the placebo group. No significant difference in inorganic phosphate and 2,3 DPG was observed later on in the two groups. Psychological and clinical tests also indicated that the drug treated subjects felt better as compared to the placebo treated subjects. The present study suggests that low doses of phosphate increases circulating 2,3-DPG concentration which in turn brings about beneficial effect towards short term high altitude adaptation.
Dependence of mitochondrial coenzyme A uptake on the membrane electrical gradient
International Nuclear Information System (INIS)
Tahiliani, A.G.
1989-01-01
Coenzyme A (CoA) transport was studied in isolated rat heart mitochondria. Uptake of CoA was assayed by determining [3H]CoA associated with mitochondria under various conditions. Various oxidizable substrates including alpha-ketoglutarate, succinate, or malate stimulated CoA uptake. The membrane proton (delta pH) and electrical (delta psi) gradients, which dissipated with time in the absence of substrate, were maintained at their initial levels throughout the incubation in the presence of substrate. Addition of phosphate caused a concentration-dependent decrease of both delta pH and CoA uptake. Nigericin also dissipated the proton gradient and prevented CoA uptake. Valinomycin also prevented CoA uptake into mitochondria. Although the proton gradient was unaffected, the electrical gradient was completely abolished in the presence of valinomycin. Addition of 5 mM phosphate 10 min after the start of incubation prevented further uptake of CoA into mitochondria. A rapid dissipation of the proton gradient upon addition of phosphate was observed. Addition of nigericin or valinomycin 10 min after the start of incubation also resulted in no further uptake of CoA into with mitochondria; valinomycin caused an apparent efflux of CoA from mitochondria. Uptake was found to be sensitive to external pH displaying a pH optimum at pHext 8.0. Although nigericin significantly inhibited CoA uptake over the pHext range of 6.75-8, maximal transport was observed around pHext 8.0-8.25. Valinomycin, on the other hand, abolished transport over the entire pH range. The results suggest that mitochondrial CoA transport is determined by the membrane electrical gradient. The apparent dependence of CoA uptake on an intact membrane pH gradient is probably the result of modulation of CoA transport by matrix pH
International Nuclear Information System (INIS)
Akana, J.; Federov, A.; Federov, E.; Novak, W.; Babbitt, P.; Almo, S.; Gerlt, J.
2006-01-01
The 'ribulose phosphate binding' superfamily defined by the Structural Classification of Proteins (SCOP) database is considered the result of divergent evolution from a common (β/α) 8 -barrel ancestor. The superfamily includes D-ribulose 5-phosphate 3-epimerase (RPE), orotidine 5'-monophosphate decarboxylase (OMPDC), and 3-keto-L-gulonate 6-phosphate decarboxylase (KGPDC), members of the OMPDC suprafamily, as well as enzymes involved in histidine and tryptophan biosynthesis that utilize phosphorylated metabolites as substrates. We now report studies of the functional and structural relationships of RPE to the members of the superfamily. As suggested by the results of crystallographic studies of the RPEs from rice and Plasmodium falciparum, the RPE from Streptococcus pyogenes is activated by Zn 2+ which binds with a stoichiometry of one ion per polypeptide. Although wild type RPE has a high affinity for Zn 2+ and inactive apoenzyme cannot be prepared, the affinity for Zn 2+ is decreased by alanine substitutions for the two histidine residues that coordinate the Zn 2+ ion (H34A and H67A); these mutant proteins can be prepared in an inactive, metal-free form and activated by exogenous Zn 2+ . The crystal structure of the RPE was solved at 1.8 Angstroms resolution in the presence of D-xylitol 5-phosphate, an inert analogue of the D-xylulose 5-phosphate substrate. This structure suggests that the 2,3-enediolate intermediate in the 1,1-proton transfer reaction is stabilized by bidentate coordination to the Zn 2+ that also is liganded to His 34, Asp 36, His 67, and Asp 176; the carboxylate groups of the Asp residues are positioned also to function as the acid/base catalysts. Although the conformation of the bound analogue resembles those of ligands bound in the active sites of OMPDC and KGPDC, the identities of the active site residues that coordinate the essential Zn 2+ and participate as acid/base catalysts are not conserved. We conclude that only the phosphate
Energy Technology Data Exchange (ETDEWEB)
Akana,J.; Federov, A.; Federov, E.; Novak, W.; Babbitt, P.; Almo, S.; Gerlt, J.
2006-01-01
The 'ribulose phosphate binding' superfamily defined by the Structural Classification of Proteins (SCOP) database is considered the result of divergent evolution from a common ({beta}/{alpha}){sub 8}-barrel ancestor. The superfamily includes D-ribulose 5-phosphate 3-epimerase (RPE), orotidine 5'-monophosphate decarboxylase (OMPDC), and 3-keto-L-gulonate 6-phosphate decarboxylase (KGPDC), members of the OMPDC suprafamily, as well as enzymes involved in histidine and tryptophan biosynthesis that utilize phosphorylated metabolites as substrates. We now report studies of the functional and structural relationships of RPE to the members of the superfamily. As suggested by the results of crystallographic studies of the RPEs from rice and Plasmodium falciparum, the RPE from Streptococcus pyogenes is activated by Zn{sup 2+} which binds with a stoichiometry of one ion per polypeptide. Although wild type RPE has a high affinity for Zn{sup 2+} and inactive apoenzyme cannot be prepared, the affinity for Zn{sup 2+} is decreased by alanine substitutions for the two histidine residues that coordinate the Zn{sup 2+} ion (H34A and H67A); these mutant proteins can be prepared in an inactive, metal-free form and activated by exogenous Zn{sup 2+}. The crystal structure of the RPE was solved at 1.8 Angstroms resolution in the presence of D-xylitol 5-phosphate, an inert analogue of the D-xylulose 5-phosphate substrate. This structure suggests that the 2,3-enediolate intermediate in the 1,1-proton transfer reaction is stabilized by bidentate coordination to the Zn{sup 2+} that also is liganded to His 34, Asp 36, His 67, and Asp 176; the carboxylate groups of the Asp residues are positioned also to function as the acid/base catalysts. Although the conformation of the bound analogue resembles those of ligands bound in the active sites of OMPDC and KGPDC, the identities of the active site residues that coordinate the essential Zn{sup 2+} and participate as acid/base catalysts
Ando, A; Hisada, K; Ando, I
1977-10-01
Affinity of many inorganic compounds for the malignant tumor was examined, using the rats which were subcutaneously transplanted with Yoshida sarcoma. And the relations between the uptake rate into the malignant tumor and in vitro binding power to the protein were investigated in these compounds. In these experiments, the bipositive ions and anions had not affinity for the tumor tissue with a few exceptions. On the other hand, Hg, Au and Bi, which have strong binding power to the protein, showed high uptake rate into the malignant tumor. As Hg++, Au+ and Bi+++ are soft acids according to classification of Lewis acids, it was thought that these elements would bind strongly to soft base (R-SH, R-S-) present in the tumor tissue. In many hard acids (according to classification of Lewis acids), the uptake rate into the tumor was shown as a function of ionic potentials (valency/ionic radii) of the metal ions. It is presumed that the chemical bond of these hard acids in the tumor tissue is ionic bond to hard base (R-COO-, R-PO3(2-), R-SO3-, R-NH2).
Impact of phosphate limitation on PHA production in a feast-famine process.
Korkakaki, Emmanouela; van Loosdrecht, Mark C M; Kleerebezem, Robbert
2017-12-01
Double-limitation systems have shown to induce polyhydroxyalkanoates (PHA) production in chemostat studies limited in e.g. carbon and phosphate. In this work the impact of double substrate limitation on the enrichment of a PHA producing community was studied in a sequencing batch process. Enrichments at different C/P concentration ratios in the influent were established and the effect on the PHA production capacity and the enrichment community structure was investigated. Experimental results demonstrated that when a double substrate limitation is imposed at a C/P ratio in the influent in a range of 150 (C-mol/mol), the P-content of the biomass and the specific substrate uptake rates decreased. Nonetheless, the PHA storage capacity remained high (with a maximum of 84 wt%). At a C/P ratio of 300, competition in the microbial community is based on phosphate uptake, and the PHA production capacity is lost. Biomass specific substrate uptake rates are a linear function of the cellular P-content, offering advantages for scaling-up the PHA production process due to lower oxygen requirements. Copyright © 2017 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Ondino Cleante Bataglia
1984-01-01
Full Text Available Num experimento conduzido em São Simão (SP durante três anos consecutivos, em um latossolo roxo de textura média, anteriormente sob vegetação de cerrado, estudou-se o efeito da aplicação de fosfato-de-araxá, hiperfosfato, termofosfato (Yoorin e superfosfato triplo em presença e ausência de calagem, sobre o crescimento, produtividade e absorção de nutrientes pela soja cultivar Santa-Rosa. Os dados evidenciaram a importância dos nutrientes acompanhantes de fósforo dos adubos fosfatados, especialmente do cálcio, sobre o crescimento, produção de grãos e absorção de fósforo pela parte aérea da soja. Na presença de calagem, não houve diferença marcante entre os adubos sobre a produtividade e absorção do fósforo. Na sua ausência, os adubos menos solúveis, aplicados em maiores quantidades e, portanto, levando grandes quantidades de cálcio, mostraram efeitos residuais melhores que os fosfatados mais solúveis. A produtividade com a aplicação dos fosfatos menos solúveis no terceiro ano de plantio sem calagem mostrou boa correlação com a absorção de cálcio, magnésio, fósforo e com a relação Ca/Mn das folhas.One experiment was conducted during three successive growing seasons in São Simão, State of São Paulo, Brazil, to test the effect of different phosphates and liming on the uptake of phosphorus by soybeans. The phosphates were: >- rock phosphate, hyperphosphate, termophosphate (Yoorin and triple superphosphate, at rates of 100, 200 and 400kg/ha of water or 2% citric acid soluble P2O5 and a common control without phosphorus. The phosphates were broadcasted over limed or non limed plots. Dolomitic lime was applied at rates of 2500kg/ha before the first and third planting. The cultivar used was 'Santa Rosa'. Field data demonstrated the importance of the nutrients, specially calcium, carried by the phosphate together with phosphorus, on growth, grain productivity and phosphorus uptake by soybeans. In the
High inorganic phosphate causes DNMT1 phosphorylation and subsequent fibrotic fibroblast activation
Energy Technology Data Exchange (ETDEWEB)
Tan, Xiaoying [Department of Nephrology and Rheumatology, Göttingen University Medical Center, Georg August University, Göttingen (Germany); Department of Cardiology and Pneumology, Göttingen University Medical Center, Georg August University, Göttingen (Germany); Xu, Xingbo [Department of Cardiology and Pneumology, Göttingen University Medical Center, Georg August University, Göttingen (Germany); Zeisberg, Elisabeth M. [Department of Cardiology and Pneumology, Göttingen University Medical Center, Georg August University, Göttingen (Germany); German Center for Cardiovascular Research (DZHK), Göttingen (Germany); Zeisberg, Michael, E-mail: mzeisberg@med.uni-goettingen.de [Department of Nephrology and Rheumatology, Göttingen University Medical Center, Georg August University, Göttingen (Germany); German Center for Cardiovascular Research (DZHK), Göttingen (Germany)
2016-04-08
Phosphate is an essential constituent of critical cellular functions including energy metabolism, nucleic acid synthesis and phosphorylation-dependent cell signaling. Increased plasma phosphate levels are an independent risk factor for lowered life-expectancy as well as for heart and kidney failure. Nevertheless, direct cellular effects of elevated phosphate concentrations within the microenvironment are poorly understood and have been largely neglected in favor of phosphor-regulatory hormones. Because interstitial fibrosis is the common determinant of chronic progressive kidney disease, and because fibroblasts are major mediators of fibrogenesis, we here explored the effect of high extracellular phosphate levels on renal fibroblasts. We demonstrate that high inorganic phosphate directly induces fibrotic fibroblast activation associated with increased proliferative activity, increased expression of α-smooth muscle actin and increased synthesis of type I collagen. We further demonstrate that such fibroblast activation is dependent on phosphate influx, aberrant phosphorylation of DNA methyltransferase DNMT1 and aberrant CpG island promoter methylation. In summary, our studies demonstrate that elevated phosphate concentrations induce pro-fibrotic fibroblast activation independent of phospho-regulatory hormones. - Highlights: • We exposed human kidney fibroblasts to media containing 1 mM or 3 mM phosphate. • Increased phosphate influx causes phosphorylation of DNA methyltransferase Dnmt1. • Phosphorylated Dnmt1 causes promoter methylation and transcriptional silencing of RASAL1. • Depletion of RASAL1 causes increased intrinsic Ras-GTP activity and fibroblast activation. • Inorganic phosphate causes fibroblast activation independent of phospho-regulatory hormones.
Control of plant phosphate homeostasis by inositol pyrophosphates and the SPX domain.
Jung, Ji-Yul; Ried, Martina K; Hothorn, Michael; Poirier, Yves
2018-02-01
Proteins containing a SPX domain are involved in phosphate (Pi) homeostasis, including Pi transport and adaptation to Pi deficiency. The SPX domain harbors a basic surface binding Pi at low affinity and inositol pyrophosphates (PP-InsPs) at high affinity. Genetic and biochemical studies revealed that PP-InsPs serve as ligands for the SPX domain. Residues in the PHO1 SPX domain involved in PP-InsPs binding are critical for its Pi export activity, and the interaction between SPX proteins and the PHR1 transcription factor, which results in PHR1 inactivation, is promoted by PP-InsPs. Changes in PP-InsPs levels in response to Pi deficiency may thus contribute to the adaptation of plants to stress via the modulation of the activity of SPX-containing proteins and their interactors. Modulating PP-InsP levels or the affinity/specificity of the SPX domain for PP-InsP could potentially be used to engineer crops to maintain high yield under reduced Pi fertilizer input. Copyright © 2017 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Abbas El Sahili
2015-08-01
Full Text Available Periplasmic binding proteins (PBPs in association with ABC transporters select and import a wide variety of ligands into bacterial cytoplasm. They can also take up toxic molecules, as observed in the case of the phytopathogen Agrobacterium tumefaciens strain C58. This organism contains a PBP called AccA that mediates the import of the antibiotic agrocin 84, as well as the opine agrocinopine A that acts as both a nutrient and a signalling molecule for the dissemination of virulence genes through quorum-sensing. Here, we characterized the binding mode of AccA using purified agrocin 84 and synthetic agrocinopine A by X-ray crystallography at very high resolution and performed affinity measurements. Structural and affinity analyses revealed that AccA recognizes an uncommon and specific motif, a pyranose-2-phosphate moiety which is present in both imported molecules via the L-arabinopyranose moiety in agrocinopine A and the D-glucopyranose moiety in agrocin 84. We hypothesized that AccA is a gateway allowing the import of any compound possessing a pyranose-2-phosphate motif at one end. This was structurally and functionally confirmed by experiments using four synthetic compounds: agrocinopine 3'-O-benzoate, L-arabinose-2-isopropylphosphate, L-arabinose-2-phosphate and D-glucose-2-phosphate. By combining affinity measurements and in vivo assays, we demonstrated that both L-arabinose-2-phosphate and D-glucose-2-phosphate, which are the AccF mediated degradation products of agrocinopine A and agrocin 84 respectively, interact with the master transcriptional regulator AccR and activate the quorum-sensing signal synthesis and Ti plasmid transfer in A. tumefaciens C58. Our findings shed light on the role of agrocinopine and antibiotic agrocin 84 on quorum-sensing regulation in A. tumefaciens and reveal how the PBP AccA acts as vehicle for the importation of both molecules by means of a key-recognition motif. It also opens future possibilities for the
El Sahili, Abbas; Li, Si-Zhe; Lang, Julien; Virus, Cornelia; Planamente, Sara; Ahmar, Mohammed; Guimaraes, Beatriz G; Aumont-Nicaise, Magali; Vigouroux, Armelle; Soulère, Laurent; Reader, John; Queneau, Yves; Faure, Denis; Moréra, Solange
2015-08-01
Periplasmic binding proteins (PBPs) in association with ABC transporters select and import a wide variety of ligands into bacterial cytoplasm. They can also take up toxic molecules, as observed in the case of the phytopathogen Agrobacterium tumefaciens strain C58. This organism contains a PBP called AccA that mediates the import of the antibiotic agrocin 84, as well as the opine agrocinopine A that acts as both a nutrient and a signalling molecule for the dissemination of virulence genes through quorum-sensing. Here, we characterized the binding mode of AccA using purified agrocin 84 and synthetic agrocinopine A by X-ray crystallography at very high resolution and performed affinity measurements. Structural and affinity analyses revealed that AccA recognizes an uncommon and specific motif, a pyranose-2-phosphate moiety which is present in both imported molecules via the L-arabinopyranose moiety in agrocinopine A and the D-glucopyranose moiety in agrocin 84. We hypothesized that AccA is a gateway allowing the import of any compound possessing a pyranose-2-phosphate motif at one end. This was structurally and functionally confirmed by experiments using four synthetic compounds: agrocinopine 3'-O-benzoate, L-arabinose-2-isopropylphosphate, L-arabinose-2-phosphate and D-glucose-2-phosphate. By combining affinity measurements and in vivo assays, we demonstrated that both L-arabinose-2-phosphate and D-glucose-2-phosphate, which are the AccF mediated degradation products of agrocinopine A and agrocin 84 respectively, interact with the master transcriptional regulator AccR and activate the quorum-sensing signal synthesis and Ti plasmid transfer in A. tumefaciens C58. Our findings shed light on the role of agrocinopine and antibiotic agrocin 84 on quorum-sensing regulation in A. tumefaciens and reveal how the PBP AccA acts as vehicle for the importation of both molecules by means of a key-recognition motif. It also opens future possibilities for the rational design of
Guo, Haixun; Gallazzi, Fabio; Miao, Yubin
2012-06-20
The purpose of this study was to examine the melanoma targeting and pharmacokinetic properties of (67)Ga-DOTA-GGNle-CycMSHhex {(67)Ga-1,4,7,10-tetraazacyclononane-1,4,7,10-tetraacetic acid-Gly-Gly-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and (67)Ga-NOTA-GGNle-CycMSHhex {(67)Ga-1,4,7-triazacyclononane-1,4,7-triacetic acid-Gly-Gly-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-CONH2} and compare with (67)Ga-DOTA-GlyGlu-CycMSH {(67)Ga-DOTA-Gly-Glu-c[Lys-Nle-Glu-His-DPhe-Arg-Trp-Gly-Arg-Pro-Val-Asp]} we previously reported. DOTA-GGNle-CycMSHhex and NOTA-GGNle-CycMSHhex were synthesized using fluorenylmethyloxy carbonyl (Fmoc) chemistry. The melanocortin-1 (MC1) receptor binding affinity of NOTA-GGNle-CycMSHhex was determined in B16/F1 melanoma cells and compared with DOTA-GGNle-CycMSHhex. The melanoma targeting and pharmacokinetic properties of (67)Ga-NOTA-GGNle-CycMSHhex and (67)Ga-DOTA-GGNle-CycMSHhex were determined in B16/F1 melanoma-bearing C57 mice. NOTA-GGNle-CycMSHhex and DOTA-GGNle-CycMSHhex displayed comparable MC1 receptor binding affinities (1.6 vs 2.1 nM) in B16/F1 melanoma cells. Both (67)Ga-NOTA-GGNle-CycMSHhex and (67)Ga-DOTA-GGNle-CycMSHhex exhibited dramatically enhanced melanoma uptake and reduced renal uptake than (67)Ga-DOTA-GlyGlu-CycMSH in B16/F1 melanoma-bearing C57 mice. Furthermore, (67)Ga-NOTA-GGNle-CycMSHhex exhibited more favorable radiolabeling conditions (>85% radiolabeling yields started at 37 °C), as well as higher tumor/kidney uptake ratios than (67)Ga-DOTA-GGNle-CycMSHhex at 0.5, 2, and 24 h postinjection. High melanoma uptake coupled with low renal uptake highlighted the potential of (67)Ga-NOTA-GGNle-CycMSHhex for melanoma imaging and therapy.
DEFF Research Database (Denmark)
Enkavi, Giray; Mikkolainen, Heikki; Güngör, Burçin
2017-01-01
remained elusive. Here, based on an extensive set of atomistic simulations and free energy calculations, we clarify the mechanism and energetics of npc2-membrane binding and characterize the roles of physiologically relevant key lipids associated with the binding process. Our results capture in atomistic......Niemann-Pick Protein C2 (npc2) is a small soluble protein critical for cholesterol transport within and from the lysosome and the late endosome. Intriguingly, npc2-mediated cholesterol transport has been shown to be modulated by lipids, yet the molecular mechanism of npc2-membrane interactions has......). This mode is associated with cholesterol uptake and release. On the other hand, the second mode (Supine) places the cholesterol binding pocket away from the membrane surface, but has overall higher membrane binding affinity. We determined that bis(monoacylglycero)phosphate (bmp) is specifically required...
Khdhiri, Mondher; Hesse, Laura; Popa, Maria Elena; Quiza, Liliana; Lalonde, Isabelle; Meredith, Laura K.; Röckmann, Thomas; Constant, Philippe
2015-01-01
Soil-atmosphere exchange of H2 is controlled by gas diffusion and the microbial production and oxidation activities in soil. Among these parameters, the H2 oxidation activity catalyzed by soil microorganisms harboring high affinity hydrogenase is the most difficult variable to parameterize because
Wang, Junling; Li, Tao; Wu, Xiaogang; Zhao, Zhiwei
2014-01-01
Phosphate transporters (PTs), as entry points for phosphorus (P) in organisms, are involved in a number of P nutrition processes such as phosphate uptake, transport, and transfer. In the study, a PT gene 1632 bp long (named BePT) was cloned, identified, and functionally characterized from Boletus edulis. BePT was expected to encode a polypeptide with 543 amino acid residues. The BePT polypeptide belonged to the major facilitator superfamily and showed a high degree of sequence identity to the Pht1 family. A topology model revealed that BePT exhibited 12 transmembrane helices, divided into two halves, and connected by a large hydrophilic loop in the middle. A yeast mutant complementation analysis suggested that BePT was a functional PT which mediated orthophosphate uptake of yeast at micromolar concentrations. Green fluorescent protein-BePT fusion proteins expressed were extensively restricted to the plasma membrane in BePT transformed yeast, and its activity was dependent on electrochemical membrane potential. In vitro, quantitative PCR confirmed that the expression of BePT was significantly upregulated at lower phosphorus availability, which may enhance phosphate uptake and transport under phosphate starvation. Our results suggest that BePT plays a key role in phosphate acquisition in the ectomycorrhizal fungus B. edulis. Copyright © 2014 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.
An, Byungryul; Nam, Juhee; Choi, Jae-Woo; Hong, Seok-Won; Lee, Sang-Hyup
2013-11-01
In water and wastewater, phosphate is considered a critical contaminant due to cause algae blooms and eutrophication. To meet the stringent regulation of phosphate in water, a new commercial chelating resin functionalized with polyethylenimine was tested for phosphate removal by loading Cu(2+) and Fe(2+)/Fe(3+) to enhance selectivity for phosphate. Batch and column experiments showed that CR20-Cu exhibited high selectivity for phosphate over other strong anions such as sulfate. The average binary phosphate/nitrate and phosphate/sulfate factors for CR20-Cu were calculated to be 7.3 and 4.8, respectively, which were more than 0.97 and 0.22 for a commercial anion exchanger (AMP16). The optimal pH for the phosphate removal efficiency was determined to be 7. According to the fixed-bed column test, the breakthrough sequence for multiple ions was HPO4(2-)>SO4(2-)>NO3(-)>Cl(-). Saturated CR20-Cu can be regenerated using 4% NaCl at pH 7. More than 95% of the phosphate from CR20-Cu was recovered, and the phosphate uptake capacity for CR20-Cu was not reduced after 7 regeneration cycles. Copyright © 2013 Elsevier Inc. All rights reserved.
Effect of 2,3-diphosphoglycerate on oxygen affinity of blood in sickle cell anemia
Charache, Samuel; Grisolia, Santiago; Fiedler, Adam J.; Hellegers, Andre E.
1970-01-01
Blood of patients with sickle cell anemia (SS) exhibits decreased affinity for oxygen, although the oxygen affinity of hemoglobin S is the same as that of hemoglobin A. SS red cells contain more 2,3-diphosphoglycerate (DPG) than normal erythrocytes. The oxygen affinity of hemolyzed red cells is decreased by added DPG, and hemolysates prepared from SS red cells do not differ from normal hemolysates in this regard. Reduction of oxygen affinity to the levels found in intact SS red cells required DPG concentrations in excess of those found in most SS patients. The same was true of oxygen affinity of patients with pyruvate kinase deficiency. Other organic phosphates, as well as inorganic ions, are known to alter the oxygen affinity of dilute solutions of hemoglobin. These substances, the state of aggregation of hemoglobin molecules, and cytoarchitectural factors probably play roles in determining oxygen affinity of both normal and SS red cells. PMID:5443181
short communication agronomic effectiveness of novel phosphate
African Journals Online (AJOL)
igneous Dorowa (Zimbabwe) phosphate rock was investigated in a greenhouse ... are higher than the levels considered desirable for acidulation was selected based on proportions ... The analysis for dry matter yield of and P uptake by maize ...
Biological phosphorus uptake under anoxic and aerobic conditions
DEFF Research Database (Denmark)
Kerrn-Jespersen, Jens Peter; Henze, Mogens
1993-01-01
Biological phosphorus removal was investigated under anoxic and aerobic conditions. Tests were made to establish whether phosphorus accumulating bacteria can take up phosphate under anoxic conditions and thus utilise nitrate as oxidant. Furthermore, it was tested how the amount of organic matter...... as oxidant. The phosphorus uptake was more rapid under aerobic conditions than under anoxic conditions. The explanation of this is that all phosphorus accumulating bacteria take up phosphate under aerobic conditions, whereas only part of the phosphorus accumulating bacteria take up phosphate under anoxic...
Nishanth, D; Biswas, D R
2008-06-01
An attempt was made to study the efficient use of rice straw and indigenous source of phosphorus and potassium in crop production through composting technology. Various enriched composts were prepared using rice straw, rock phosphate (RP), waste mica and bioinoculant (Aspergillus awamori) and kinetics of release of phosphorus and potassium from enriched composts and their effect on yield and nutrient uptake by wheat (Triticum aestivum) were carried out. Results showed sharp increases in release in water-soluble P and K from all the composts at 8th to 12th day of leaching, thereafter, it decreased gradually. Maximum release of water-soluble P and K were obtained in ordinary compost than enriched composts during the initial stages of leaching, but their differences narrowed down at latter stages. Data in pot experiments revealed that enriched composts performed poorly than diammonium phosphate during initial stages of crop growth, but they out yielded at the latter stages, particularly at maturity stage, as evident from their higher yield, uptake, nutrient recoveries and fertility status of P and K in soils. Moreover, enriched composts prepared with RP and waste mica along with A. awamori resulted in significantly higher biomass yield, uptake and recoveries of P and K as well as available P and K in soils than composts prepared without inoculant. Results indicated that enriched compost could be an alternate technology for the efficient management of rice straw, low-grade RP and waste mica in crop production, which could help to reduce the reliance on costly chemical fertilizers.
Effect of altitude on oxygen binding by hemoglobin and on organic phosphate levels
Lenfant, Claude; Torrance, John; English, Eugenia; Finch, Clement A.; Reynafarje, Cesar; Ramos, Jose; Faura, Jose
1968-01-01
The relationship between oxygen dissociation and 2,3-diphosphoglycerate (2,3-DPG) in the red cell has been studied in subjects moving from low to high altitude and vice versa. Within 24 hr following the change in altitude there was a change in hemoglobin affinity for oxygen; this modification therefore represents an important rapid adaptive mechanism to anoxia. A parallel change occurred in the organic phosphate content of the red cell. While this study does not provide direct evidence of a cause-effect relationship, the data strongly suggest that with anoxia, the observed rise in organic phosphate content of the red cell is responsible for increased availability of oxygen to tissues. Images PMID:5725278
Role of magnesium on the biomimetic deposition of calcium phosphate
Sarma, Bimal K.; Sarma, Bikash
2016-10-01
Biomimetic depositions of calcium phosphate (CaP) are carried out using simulated body fluid (SBF), calcifying solution and newly developed magnesium containing calcifying solution. Calcium phosphate has a rich phase diagram and is well known for its excellent biocompatibility and bioactivity. The most common phase is hydroxyapatite (HAp), an integral component of human bone and tooth, widely used in orthopedic and dental applications. In addition, calcium phosphate nanoparticles show promise for the targeted drug delivery. The doping of calcium phosphate by magnesium, zinc, strontium etc. can change the protein uptake by CaP nanocrystals. This work describes the role of magnesium on the nucleation and growth of CaP on Ti and its oxide substrates. X-ray diffraction studies confirm formation of HAp nanocrystals which closely resemble the structure of bone apatite when grown using SBF and calcifying solution. It has been observed that magnesium plays crucial role in the nucleation and growth of calcium phosphate. A low magnesium level enhances the crystallinity of HAp while higher magnesium content leads to the formation of amorphous calcium phosphate (ACP) phase. Interestingly, the deposition of ACP phase is rapid when magnesium ion concentration in the solution is 40% of calcium plus magnesium ions concentration. Moreover, high magnesium content alters the morphology of CaP films.
Uptake by Plants of Radiostrontium from Contaminated Soils
DEFF Research Database (Denmark)
Andersen, A. J.
1965-01-01
In a recent report from this department it was shown that the extractability of radiostrontium from contaminated soil samples was effectively reduced by heat treatment and by the addition of phosphate to the soil. It was pointed out that, under emergency conditions, heat-treatment of the contamin......In a recent report from this department it was shown that the extractability of radiostrontium from contaminated soil samples was effectively reduced by heat treatment and by the addition of phosphate to the soil. It was pointed out that, under emergency conditions, heat......-treatment of the contaminated soil surface and heavy phosphate application might thus reduce the uptake by plants of radiostrontium more efficiently than liming, which is only effective in soils of low calcium status. In the investigation reviewed here the influence of heat treatment and superphosphate application on the plant...... uptake of radiostrontium was examined in pot experiments. For comparison the effect of applying calcium carbonate to the contaminated soil surface was also determined....
DEFF Research Database (Denmark)
Maiti, Soumen K.; Singh, Kamaleshwar P.; Eliasson Lantz, Anna
2010-01-01
may experience catabolite repression by one or more of the substrates. Availability of reliable process models is a key bottleneck in optimization of such processes. Here we present a structured kinetic model to describe the growth, substrate uptake and product formation for the glycopeptide....... The model is also able to predict key phenomena such as simultaneous uptake of glucose and glycerol but with different specific uptake rates, and inhibition of glycopeptide production by high intracellular phosphate levels. The model is successfully applied to both production and seed medium with varying....... The model may have applications in optimizing seed transfer, medium composition, and feeding strategy for maximizing production....
Jauzein, Cécile; Couet, Douglas; Blasco, Thierry; Lemée, Rodolphe
2017-05-01
Environmental factors that shape dynamics of benthic toxic blooms are largely unknown. In particular, for the toxic dinoflagellate Ostreopsis cf. ovata, the importance of the availability of nutrients and the contribution of the inorganic and organic pools to growth need to be quantified in marine coastal environments. The present study aimed at characterizing N-uptake of dissolved inorganic and organic sources by O. cf. ovata cells, using the 15 N-labelling technique. Experiments were conducted taking into account potential interactions between nutrient uptake systems as well as variations with the diel cycle. Uptake abilities of O. cf. ovata were parameterized for ammonium (NH 4 + ), nitrate (NO 3 - ) and N-urea, from the estimation of kinetic and inhibition parameters. In the range of 0 to 10μmolNL -1 , kinetic curves showed a clear preference pattern following the ranking NH 4 + >NO 3 - >N-urea, where the preferential uptake of NH 4 + relative to NO 3 - was accentuated by an inhibitory effect of NH 4 + concentration on NO 3 - uptake capabilities. Conversely, under high nutrient concentrations, the preference for NH 4 + relative to NO 3 - was largely reduced, probably because of the existence of a low-affinity high capacity inducible NO 3 - uptake system. Ability to take up nutrients in darkness could not be defined as a competitive advantage for O. cf. ovata. Species competitiveness can also be defined from nutrient uptake kinetic parameters. A strong affinity for NH 4 + was observed for O. cf. ovata cells that may partly explain the success of this toxic species during the summer season in the Bay of Villefranche-sur-mer (France). Copyright © 2017 Elsevier B.V. All rights reserved.
Molecular basis of a high affinity murine interleukin-5 receptor.
Devos, R; Plaetinck, G; Van der Heyden, J; Cornelis, S; Vandekerckhove, J; Fiers, W; Tavernier, J
1991-01-01
The mouse interleukin-5 receptor (mIL-5R) consists of two components one of which, the mIL-5R alpha-chain, binds mIL-5 with low affinity. Recently we demonstrated that monoclonal antibodies (Mabs) recognizing the second mIL-5R beta-chain, immunoprecipitate a p130-140 protein doublet which corresponds to the mIL-3R and the mIL-3R-like protein, the latter chain for which so far no ligand has been identified. In this study we show that a high affinity mIL-5R can be reconstituted on COS1 cells by...
Uptake of CrO42- ions by Fe-treated tri-calcium phosphate
International Nuclear Information System (INIS)
Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E.
2010-01-01
CrO 4 2- ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10 -4 M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO 4 2- ions was 7.10 x 10 -3 mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters ΔH 0 , ΔG 0 and ΔS 0 were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)
Seguin, Alexandra; Santos, Renata; Pain, Debkumar; Dancis, Andrew; Camadro, Jean-Michel; Lesuisse, Emmanuel
2011-02-25
Saccharomyces cerevisiae cells lacking the yeast frataxin homologue (Δyfh1) accumulate iron in the mitochondria in the form of nanoparticles of ferric phosphate. The phosphate content of Δyfh1 mitochondria was higher than that of wild-type mitochondria, but the proportion of mitochondrial phosphate that was soluble was much lower in Δyfh1 cells. The rates of phosphate and iron uptake in vitro by isolated mitochondria were higher for Δyfh1 than wild-type mitochondria, and a significant proportion of the phosphate and iron rapidly became insoluble in the mitochondrial matrix, suggesting co-precipitation of these species after oxidation of iron by oxygen. Increasing the amount of phosphate in the medium decreased the amount of iron accumulated by Δyfh1 cells and improved their growth in an iron-dependent manner, and this effect was mostly transcriptional. Overexpressing the major mitochondrial phosphate carrier, MIR1, slightly increased the concentration of soluble mitochondrial phosphate and significantly improved various mitochondrial functions (cytochromes, [Fe-S] clusters, and respiration) in Δyfh1 cells. We conclude that in Δyfh1 cells, soluble phosphate is limiting, due to its co-precipitation with iron.
International Nuclear Information System (INIS)
Casanova, E.; Salas, A.M.; Toro, M.
2002-01-01
Field experiments were conducted to evaluate the efficiency of natural and modified rock phosphate using conventional and isotopic techniques in an acid soil from El Pao, Cojedes state, Venezuela, using maize and sorghum with the application of different phosphate fertilizers to measure dry matter production, P accumulated in plant, efficiency parameters using isotopic techniques or yield. Finally, commercial plots were established with the application of soluble P fertilizers and rock phosphate products to validate the results obtained in the field experiments. The results showed highly significant differences between partially acidulated rock phosphate, natural rock phosphate, and the check plot in dry matter production, and P accumulation in plant and grain yield. When the efficiency parameters were evaluated in microplots with 32 P-TSP at 60 days of plant growth, it confirmed results obtained in semi commercial plots where the P in the plant derived from the fertilizer was 46% with partially acidulated rock phosphate (PAR) and 14% with natural Riecito rock phosphate (RR). Utilization coefficients of P by the plants were 34.2 and 8.8% for both treatments, respectively. The Substitution relation parameter showed that just 0.8 kg of P of PAR or 3.1 kg P of RR was required to produce the same yield as 1 kg P of TSP. These results were further validated in 5 ha commercial plots using corn and sorghum. (author)
Vermeiren, Céline; Motte, Philippe; Viot, Delphine; Mairet-Coello, Georges; Courade, Jean-Philippe; Citron, Martin; Mercier, Joël; Hannestad, Jonas; Gillard, Michel
2018-02-01
Lilly/Avid's AV-1451 is one of the most advanced tau PET tracers in the clinic. Although results obtained in Alzheimer's disease patients are compelling, discrimination of tracer uptake in healthy individuals and patients with supranuclear palsy (PSP) is less clear as there is substantial overlap of signal in multiple brain regions. Moreover, accurate quantification of [ 18 F]AV-1451 uptake in Alzheimer's disease may not be possible. The aim of the present study was to characterize the in vitro binding of AV-1451 to understand and identify potential off-target binding that could explain the poor discrimination observed in PSP patients. [ 3 H]AV-1451 and AV-1451 were characterized in in vitro binding assays using recombinant and native proteins/tissues from postmortem samples of controls and Alzheimer's disease and PSP patients. [ 3 H]AV-1451 binds to multiple sites with nanomolar affinities in brain homogenates and to tau fibrils isolated from Alzheimer's disease or PSP patients. [ 3 H]AV-1451 also binds with similarly high affinities in brain homogenates devoid of tau pathology. This unexpected binding was demonstrated to be because of nanomolar affinities of [ 3 H]AV-1451 for monoamine oxidase A and B enzymes. High affinity of AV-1451 for monoamine oxidase proteins may limit its utility as a tau PET tracer in PSP and Alzheimer's disease because of high levels of monoamine oxidase expression in brain regions also affected by tau deposition, especially if monoamine oxidase levels change over time or with a treatment intervention. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.
Directory of Open Access Journals (Sweden)
Lixin Ma
2007-05-01
Full Text Available Gastrin-releasing peptide (GRP receptors are overexpressed on several types of human cancer cells, including breast, prostate, small cell lung, and pancreatic cancers. Bombesin (BBN, a 14–amino acid peptide that is an analogue of human GRP, binds to GRP receptors with very high affinity and specificity. The aim of this study was to develop a new fluorescent probe based on BBN having high tumor uptake and optimal pharmacokinetics for specific targeting and optical imaging of human breast cancer tissue. In this study, solid-phase peptide synthesis was used to produce H2N-glycylglycylglycine-BBN[7–14]NH2 peptide with the following general sequence: H2N-G-G-G-Q-W-A-V-G-H-L-M-(NH2. This conjugate was purified by reversed-phase high-performance liquid chromatography and characterized by electrospray-ionization mass spectra. The fluorescent probe Alexa Fluor 680-G-G-G-BBN[7–14]NH2 conjugate was prepared by reaction of Alexa Fluor 680 succinimidyl ester to H2N-G-G-G-BBN[7–14]NH2 in dimethylformamide (DMF. In vitro competitive binding assays, using 125I-Tyr4-BBN as the radiolabeling gold standard, demonstrated an inhibitory concentration 50% value of 7.7 ± 1.4 nM in human T-47D breast cancer cells. Confocal fluorescence microscopy images of Alexa Fluor 680-G-G-G-BBN[7–14]NH2 in human T-47D breast cancer cells indicated specific uptake, internalization, and receptor blocking of the fluorescent bioprobe in vitro. In vivo investigations in SCID mice bearing xenografted T-47D breast cancer lesions demonstrated the ability of this new conjugate to specifically target tumor tissue with high selectivity and affinity.
Inositol hexa-phosphate: a potential chelating agent for uranium
International Nuclear Information System (INIS)
Cebrian, D.; Tapia, A.; Real, A.; Morcillo, M.A.
2007-01-01
Chelation therapy is an optimal method to reduce the radionuclide-related risks. In the case of uranium incorporation, the treatment of choice is so far i.v infusion of a 1.4% sodium bicarbonate solution, but the efficacy has been proved to be not very high. In this study, we examine the efficacy of some substances: bicarbonate, citrate, diethylenetriamine pentaacetic acid (DTPA), ethidronate (EHBP) and inositol hexa-phosphate (phytic acid) to chelate uranium using a test developed by Braun et al. Different concentrations of phytic acid, an abundant component of plant seeds that is widely distributed in animal cells and tissues in substantial levels, were tested and compared to the same concentrations of sodium citrate, bicarbonate, EHBP and DTPA. The results showed a strong affinity of inositol hexa-phosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo. (authors)
Krainer, Georg; Keller, Sandro
2015-04-01
Isothermal titration calorimetry (ITC) is the gold standard for dissecting the thermodynamics of a biomolecular binding process within a single experiment. However, reliable determination of the dissociation constant (KD) from a single titration is typically limited to the range 100 μM>KD>1 nM. Interactions characterized by a lower KD can be assessed indirectly by so-called competition or displacement assays, provided that a suitable competitive ligand is available whose KD falls within the directly accessible window. However, this protocol is limited by the fact that it necessitates at least two titrations to characterize one high-affinity inhibitor, resulting in considerable consumption of both sample material and time. Here, we introduce a fast and efficient ITC displacement assay that allows for the simultaneous characterization of both a high-affinity ligand and a moderate-affinity ligand competing for the same binding site on a receptor within a single experiment. The protocol is based on a titration of the high-affinity ligand into a solution containing the moderate-affinity ligand bound to the receptor present in excess. The resulting biphasic binding isotherm enables accurate and precise determination of KD values and binding enthalpies (ΔH) of both ligands. We discuss the theoretical background underlying the approach, demonstrate its practical application to metal ion chelation, explore its potential and limitations with the aid of simulations and statistical analyses, and elaborate on potential applications to protein-inhibitor interactions. Copyright © 2014 Elsevier Inc. All rights reserved.
High radio-isotope uptakes in patients with hypothyroidism
Energy Technology Data Exchange (ETDEWEB)
Wing, J.; Kalk, W.J.; Ganda, C. (University of the Witwatersrand, Johannesburg (South Africa). Dept. of Medicine)
1982-12-04
Hypothyroidism is usually associated with a low radio-isotope uptake by the thyriod gland. We report 8 cases of Hashimoto's thyroiditis with clinical and biochemical hypothyroidism and with borderline high or overtly increased technetium-99m pertechnetate and/or iodine-131 uptakes.
Selective uptake of manganese in seawater by hybrid microcapsules
International Nuclear Information System (INIS)
Kuzumaki, Takenori; Yan, Wu; Mimura, Hitoshi; Niibori, Yuichi
2008-01-01
The selective separation and recovery of low concentrated elements in seawater are very important subjects for the advancement of environmental monitoring. Selective uptake of manganese from seawater was carried out by using two kinds of microcapsules (MCs) including activated carbon (AC) and insoluble tannin (T). The adsorbents, AC and T, having affinity for manganese, were enclosed into MCs (ACMS, TMC) by sol-gel method using matrices of biopolymer (calcium alginate gel polymer, CaALG). The uptake properties and selectivity of Mn 2+ (1 ppm) for MCs were examined by batch method. Relatively large uptake percentages of Mn 2+ above 80% were obtained within 1 h, and the uptake percentage above 80% was kept at pH 3-6. The uptake order was found to be T, AC, CaALG > ACMC, TMC. The uptake of Mn 2+ decreased with increasing Na + ion concentration. This tendency depends on the swelling property of CaALG; it tends to solate in the presence of highly concentrated Na + ions. The manganese ions were adsorbed on CaALG, ACMC and TMC from seawater containing 1,000 ppm Mn 2+ . ACMC and TMC had selectivity to Mn 2+ , and, especially, the matrices of CaALG also had an excellent uptake and selectivity properties. (author)
International Nuclear Information System (INIS)
Alexandratos, Spiro D.
2007-01-01
Polymer-supported reagents are comprised of crosslinked polymer networks that have been modified with ligands capable of selective metal ion complexation. Applications of these polymers are in environmental remediation, ion chromatography, sensor technology, and hydrometallurgy. Bifunctional polymers with diphosphonate/sulfonate ligands have a high selectivity for actinide ions. The distribution coefficient for the uranyl ion from 1 M nitric acid is 70,000, compared to 900 for the monophosphonate/sulfonate polymer and 200 for the sulfonic acid ion-exchange resin. A bifunctional trihexyl/triethylammonium polymer has a high affinity and selectivity for pertechnetate and perchlorate anions from groundwater. In one example, its distribution coefficient for perchlorate ions in the presence of competing anions is 3,300,000, compared to 203,180 for a commercially available anion-exchange resin. Polystyrene modified with N-methyl-D-glucamine ligands is capable of selectively complexing arsenate from groundwater. It complexes 99% of the arsenate present in a solution of 100 mg/L arsenate with 560 mg/L sulfate ions. Its selectivity is retained even in the presence of 400 mg/L phosphate. There is no affinity for arsenate above pH 9, allowing for the polymer to be regenerated with moderate alkali solution. In studies aimed at developing a Hg(II)-selective resin, simple amine resins were found to have a high Hg(II) affinity and that affinity is dependent upon the solution pH and the counterion
Chen, Jiandong
2016-01-01
ABSTRACT The l-arabinose-inducible araBAD promoter (PBAD) enables tightly controlled and tunable expression of genes of interest in a broad range of bacterial species. It has been used successfully to study bacterial sRNA regulation, where PBAD drives expression of target mRNA translational fusions. Here we report that in Escherichia coli, Spot 42 sRNA regulates PBAD promoter activity by affecting arabinose uptake. We demonstrate that Spot 42 sRNA represses araF, a gene encoding the AraF subunit of the high-affinity low-capacity arabinose transporter AraFGH, through direct base-pairing interactions. We further show that endogenous Spot 42 sRNA is sufficient to repress araF expression under various growth conditions. Finally, we demonstrate this posttranscriptional repression has a biological consequence, decreasing the induction of PBAD at low levels of arabinose. This problem can be circumvented using strategies reported previously for avoiding all-or-none induction behavior, such as through constitutive expression of the low-affinity high-capacity arabinose transporter AraE or induction with a higher concentration of inducers. This work adds araF to the set of Spot 42-regulated genes, in agreement with previous studies suggesting that Spot 42, itself negatively regulated by the cyclic AMP (cAMP) receptor protein-cAMP complex, reinforces the catabolite repression network. IMPORTANCE The bacterial arabinose-inducible system is widely used for titratable control of gene expression. We demonstrate here that a posttranscriptional mechanism mediated by Spot 42 sRNA contributes to the functionality of the PBAD system at subsaturating inducer concentrations by affecting inducer uptake. Our finding extends the inputs into the known transcriptional control for the PBAD system and has implications for improving its usage for tunable gene expression. PMID:27849174
Characterization of (/sup 3/H)5-hydroxytryptamine uptake within rat cerebrovascular tree
Energy Technology Data Exchange (ETDEWEB)
Amenta, F.; Rossi, M. de; Mione, M.C.; Geppetti, P.
1985-06-07
The in vitro uptake of tritiated serotonin ((/sup 3/H)5HT) was studied in a preparation of rat extracerebral arteries. The uptake of (/sup 3/H)5HT was time- and temperature-dependent and of high affinity; linear regression analysis gave a Ksub(m) value of 6.48 X 10/sup 7/ M for the specific uptake. Histoautoradiographic studies showed the highest density of silver grains at the level of the adventitial-medial border of the basilar artery. Fluoxetine inhibited the accumulation of silver grains within the adventitial-medial border in the blood vessel studied. The present data further support the view that a neuronal serotonergic system may play a role in the control of blood flow in the cerebrovascular tree.
DEFF Research Database (Denmark)
Thingholm, Tine E; Jensen, Ole N
2009-01-01
The combination of immobilized metal affinity chromatography (IMAC) and mass spectrometry is a widely used technique for enrichment and sequencing of phosphopeptides. In the IMAC method, negatively charged phosphate groups interact with positively charged metal ions (Fe3+, Ga3+, and Al3...
Vassbotn, F S; Langeland, N; Holmsen, H
1990-09-01
Porcine PDGF was found to increase [3H]inositol trisphosphate, [3H]thymidine incorporation and 32P-labelling of polyphosphoinositides in C3H/10T1/2 Cl 8 fibroblasts. These responses to PDGF stimulation were all inhibited by 5 mM neomycin, a polycationic aminoglycoside formerly known to inhibit polyphosphoinositide turnover. PDGF also markedly increased the cellular uptake of inorganic [32P]Pi. This response of PDGF was not inhibited by neomycin (5 mM). Thus, neomycin inhibited PDGF-induced IP3 formation, 32P-labelling of polyphosphoinositides and DNA synthesis, but not cellular uptake of inorganic phosphate. These effects of neomycin suggest a bifurcation of the initial part of the PDGF-induced signal transduction, separating at the receptor level or before phospholipase C activation.
Selective induction of high-ouabain-affinity isoform of Na+-K+-ATPase by thyroid hormone
International Nuclear Information System (INIS)
Haber, R.S.; Loeb, J.N.
1988-01-01
The administration of thyroid hormone is known to result in an induction of the Na + -K + -adenosinetriphosphatase (Na + -K + -ATPase) in rat skeletal muscle and other thyroid hormone-responsive tissues. Since the Na + -K + -ATPase in a variety of mammalian tissues has recently been reported to exist in at least two forms distinguishable by differing affinities for the inhibitory cardiac glycoside ouabain. The authors have studied the effects of 3,3',5-triiodo-L-thyronine (T 3 ) treatment on these two forms of the enzyme in rat diaphragm. The inhibition of Na + -K + -ATPase activity in a crude membrane fraction by varying concentrations of ouabain conformed to a biphasic pattern consistent with the presence of two distinct isoforms with inhibition constants (K I s) for ouabain of ∼10 -7 and 10 -4 M, respectively. Measurement of the specific binding of [ 3 H]ouabain to these membranes confirmed the presence of a class of high-affinity ouabain binding sites with a dissociation constant (K d ) of slightly less than 10 -7 M, whose maximal binding capacity was increased by T 3 treatment by 185%. Binding studies in unfractionated homogenates of diaphragm similarly demonstrated the presence of high-affinity sites whose maximal binding capacity was increased by T 3 treatment. Quantitation of both the high- and low-ouabain-affinity forms of the Na + -K + -ATPase by ouabain-dependent phosphorylation from [ 32 P]orthophosphate confirmed that T 3 treatment markedly increased the number of high-affinity sites while having little effect on the number of low-affinity sites. These observations provide, to our knowledge, the first demonstration that these two forms of the Na + -K + -ATPase are subject to selective hormonal induction
Autoradiographic localization of 3H-paroxetine-labeled serotonin uptake sites in rat brain
International Nuclear Information System (INIS)
De Souza, E.B.; Kuyatt, B.L.
1987-01-01
Paroxetine is a potent and selective inhibitor of serotonin uptake into neurons. Serotonin uptake sites have been identified, localized, and quantified in rat brain by autoradiography with 3H-paroxetine; 3H-paroxetine binding in slide-mounted sections of rat forebrain was of high affinity (KD = 10 pM) and the inhibition affinity constant (Ki) values of various drugs in competing 3H-paroxetine binding significantly correlated with their reported potencies in inhibiting synaptosomal serotonin uptake. Serotonin uptake sites labeled by 3H-paroxetine were highly concentrated in the dorsal and median raphe nuclei, central gray, superficial layer of the superior colliculus, lateral septal nucleus, paraventricular nucleus of the thalamus, and the islands of Calleja. High concentrations of 3H-paroxetine binding sites were found in brainstem areas containing dopamine (substantia nigra and ventral tegmental area) and norepinephrine (locus coeruleus) cell bodies. Moderate concentrations of 3H-paroxetine binding sites were present in laminae I and IV of the frontal parietal cortex, primary olfactory cortex, olfactory tubercle, regions of the basal ganglia, septum, amygdala, thalamus, hypothalamus, hippocampus, and some brainstem areas including the interpeduncular, trigeminal, and parabrachial nuclei. Lower densities of 3H-paroxetine binding sites were found in other regions of the neocortex and very low to nonsignificant levels of binding were present in white matter tracts and in the cerebellum. Lesioning of serotonin neurons with 3,4-methylenedioxyamphetamine caused large decreases in 3H-paroxetine binding. The autoradiographic distribution of 3H-paroxetine binding sites in rat brain corresponds extremely well to the distribution of serotonin terminals and cell bodies as well as with the pharmacological sites of action of serotonin
International Nuclear Information System (INIS)
Zapata, F.; Zaharah, A.R.
2002-01-01
Phosphorus (P) inputs are required for sustainable agricultural production in most acid soils of the tropics and subtropics. Phosphate rocks (PR) and organic materials have been suggested as alternative P sources in these soils. Quantitative information on the P availability from sewage sludge (SL) is scanty. Methods to improve the effectiveness of PR such as partial acidulation and compaction with water-soluble P sources have been recommended. The objective of this greenhouse study was to evaluate the relative agronomic effectiveness (RAE) of Florida PR and sewage sludges (irradiated and non-irradiated) applied alone and in mixture with a water-soluble source (triple superphosphate, TSP) at two rates (50 and 150 mg P kg -1 soil). The 32 P isotope dilution technique was utilised to determine the proportion of P in the plant taken up from the P fertilizer treatments. Wheat was grown on an acid loamy sand Dystric Eutrocrepts and harvested 6 weeks after planting. Results on total P uptake and the RAE of the P fertilizer sources tested indicated that the addition of 50 mg P kg -1 soil as TSP was adequate in supplying P to the 6-week-old wheat plants as compared to PR and sewage sludge. Intermediate values were obtained for the mixtures. Similar responses were observed for the high P rate. For a given P rate, phosphorus uptake from PR and SL in presence of TSP was higher than P uptake from these sources alone, indicating an enhancement effect of TSP on the effectiveness of these non-readily available sources. With respect to P uptake from PR applied alone, the relative increases in P uptake from PR due to TSP influence were 52 and 67% for the low and high P rates, respectively. The relative increases in P uptake from SL due to TSP when compared to P uptake from SL alone were 102 and 59% for the low and high P rates of application. Application of a water-soluble P fertilizer together with a non-readily available P source shows an enhancement on the P uptake from the non
Energy Technology Data Exchange (ETDEWEB)
Zapata, F. [Soil and Water Management and Crop Nutrition Section, International Atomic Energy Agency, Vienna (Austria)]. E-mail: F.Zapata@iaea.org; Zaharah, A.R. [Department of Land Management, Universiti Putra Malaysia, Serdang, Selangor (Malaysia)
2002-05-15
Phosphorus (P) inputs are required for sustainable agricultural production in most acid soils of the tropics and subtropics. Phosphate rocks (PR) and organic materials have been suggested as alternative P sources in these soils. Quantitative information on the P availability from sewage sludge (SL) is scanty. Methods to improve the effectiveness of PR such as partial acidulation and compaction with water-soluble P sources have been recommended. The objective of this greenhouse study was to evaluate the relative agronomic effectiveness (RAE) of Florida PR and sewage sludges (irradiated and non-irradiated) applied alone and in mixture with a water-soluble source (triple superphosphate, TSP) at two rates (50 and 150 mg P kg{sup -1} soil). The {sup 32}P isotope dilution technique was utilised to determine the proportion of P in the plant taken up from the P fertilizer treatments. Wheat was grown on an acid loamy sand Dystric Eutrocrepts and harvested 6 weeks after planting. Results on total P uptake and the RAE of the P fertilizer sources tested indicated that the addition of 50 mg P kg{sup -1} soil as TSP was adequate in supplying P to the 6-week-old wheat plants as compared to PR and sewage sludge. Intermediate values were obtained for the mixtures. Similar responses were observed for the high P rate. For a given P rate, phosphorus uptake from PR and SL in presence of TSP was higher than P uptake from these sources alone, indicating an enhancement effect of TSP on the effectiveness of these non-readily available sources. With respect to P uptake from PR applied alone, the relative increases in P uptake from PR due to TSP influence were 52 and 67% for the low and high P rates, respectively. The relative increases in P uptake from SL due to TSP when compared to P uptake from SL alone were 102 and 59% for the low and high P rates of application. Application of a water-soluble P fertilizer together with a non-readily available P source shows an enhancement on the P
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A new approach for the separation of antithrombin III with high performance affinity chromatography (HPAC) was described. A novel monodisperse,non-porous,cross-linked poly (glycidyl methacrylate) beads (PGMA) were used as the affinity support. With the water-soluble carbodiimide,heparin was linked covalently to amino-PGMA-beads,which was prepared by amination of PGMA. The adsorbent obtained exhibits high binding activity to antithrombin III (ATIII),good resolution and excellent mechanical properties and can be used under high flow rate.
Hepatic uptake of technetium-99m diphosphonate in thalassemia major
International Nuclear Information System (INIS)
Levy, H.M.; Smith, R.
1986-01-01
Two cases of thalassemia major are presented in which bone scintigraphy demonstrated diffuse hepatic uptake of Tc-99m diphosphonate. Although abnormal splenic and renal uptake of Tc-99m phosphates has been reported in patients with thalassemia major, hepatic uptake has not been reported previously. This scintigraphic finding is presumably due to increased iron deposition in the liver, resulting from increased iron turnover and retention in these patients and from multiple previous blood transfusions
International Nuclear Information System (INIS)
Wild, Damian; Schmitt, Joerg S.; Ginj, Mihaela; Maecke, Helmut R.; Bernard, Bert F.; Krenning, Eric; Jong, Marion de; Wenger, Sandra; Reubi, Jean-Claude
2003-01-01
Earlier studies have shown that modification of the octapeptide octreotide in positions 3 and 8 may result in compounds with increased somatostatin receptor affinity that, if radiolabelled, display improved uptake in somatostatin receptor-positive tumours. The aim of a recent research study in our laboratory was to employ the parallel peptide synthesis approach by further exchanging the amino acid in position 3 of octreotide and coupling the macrocyclic chelator DOTA(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) to these peptides for labelling with radiometals like gallium-67 or -68, indium-111, yttrium-90 and lutetium-177. The purpose was to find radiopeptides with an improved somatostatin receptor binding profile in order to extend the spectrum of targeted tumours. A first peptide, [ 111 In, 90 Y-DOTA]-1-Nal 3 -octreotide ( 111 In, 90 Y-DOTA-NOC), was isolated which showed an improved profile. In III -DOTA-NOC exhibited the following IC 50 values (nM) when studied in competition with [ 125 I][Leu 8 , d-Trp 22 , Tyr 25 ]somatostatin-28 (values for Y III -DOTA-NOC are shown in parentheses): sstr2, 2.9±0.1 (3.3±0.2); sstr3, 8±2 (26±1.9); sstr5, 11.2±3.5 (10.4±1.6). Affinity towards sstr1 and 4 was very low or absent. In III -DOTA-NOC is superior to all somatostatin-based radiopeptides having this particular type of binding profile, including DOTA-lanreotide, and has three to four times higher binding affinity to sstr2 than In III ,Y III -DOTA-Tyr 3 -octreotide (In III ,Y III -DOTA-TOC). In addition, [ 111 In]DOTA-NOC showed a specific and high rate of internalization into AR4-2J rat pancreatic tumour cells which, after 4 h, was about two times higher than that of [ 111 In]DOTA-TOC and three times higher than that of [ 111 In]DOTA-octreotide ([ 111 In]DOTA-OC). The internalized radiopeptides were externalized intact upon 2 h of internalization followed by an acid wash. After 2-3 h of externalization a plateau is reached, indicating a steady
Hankosky, Emily R; Joolakanti, Shyam R; Nickell, Justin R; Janganati, Venumadhav; Dwoskin, Linda P; Crooks, Peter A
2017-12-15
A small library of fluoroethoxy-1,4-diphenethyl piperidine and fluoroethoxy-1,4-diphenethyl piperazine derivatives were designed, synthesized and evaluated for their ability to inhibit [ 3 H]dopamine (DA) uptake at the vesicular monoamine transporter-2 (VMAT2) and dopamine transporter (DAT), [ 3 H]serotonin (5-HT) uptake at the serotonin transporter (SERT), and [ 3 H]dofetilide binding at the human-ether-a-go-go-related gene (hERG) channel. The majority of the compounds exhibited potent inhibition of [ 3 H]DA uptake at VMAT2, Ki changes in the nanomolar range (K i = 0.014-0.073 µM). Compound 15d exhibited the highest affinity (K i = 0.014 µM) at VMAT2, and had 160-, 5-, and 60-fold greater selectivity for VMAT2 vs. DAT, SERT and hERG, respectively. Compound 15b exhibited the greatest selectivity (>60-fold) for VMAT2 relative to all the other targets evaluated, and 15b had high affinity for VMAT2 (K i = 0.073 µM). Compound 15b was considered the lead compound from this analog series due to its high affinity and selectivity for VMAT2. Copyright © 2017 Elsevier Ltd. All rights reserved.
Hepatic bilirubin uptake in the isolated perfused rat liver is not facilitated by albumin binding
International Nuclear Information System (INIS)
Stollman, Y.R.; Gaertner, U.; Theilmann, L.; Ohmi, N.; Wolkoff, A.W.
1983-01-01
Bilirubin uptake by the liver has kinetic characteristics which suggest carrier-mediation. Bilirubin is readily bound to albumin. A liver cell surface receptor for albumin has been postulated. The present study was designed to examine directly whether albumin facilitates the hepatic uptake of bilirubin and whether uptake of bilirubin depends on binding to albumin. Rat liver was perfused with a protein-free fluorocarbon medium, and single-pass uptake of 1, 10, or 200 nmol of [ 3 H]bilirubin was determined after injection as an equimolar complex with 125 I-albumin, with 125 I-ligandin, or free with only a [ 14 C]sucrose reference. Uptake of 10 nmol of [ 3 H]bilirubin was 67.5 +/- 3.7% of the dose when injected with 125 I-albumin, 67.4 +/- 6.5% when injected with 125 I-ligandin, and 74.9 +/- 2.4% when injected with [ 14 C]sucrose (P greater than 0.1). At 200 nmol, uptake fell to 46.4 +/- 3.1% ( 125 I-albumin) and 63.3 +/- 3.4% [( 14 C]sucrose) of injected [ 3 H]bilirubin (P less than 0.01), which suggests saturation of the uptake mechanism. When influx was quantitated by the model of Goresky, similar results were obtained. When [ 3 H]bilirubin was injected simultaneously with equimolar 125 I-albumin and a [ 14 C]sucrose reference, there was no delay in 125 I-albumin transit as compared with that of [ 14 C]sucrose. This suggested that the off-rate of albumin from a putative hepatocyte receptor would have to be very rapid, which is unusual for high affinity receptor-ligand interaction. There was no evidence for facilitation of bilirubin uptake by binding to albumin or for interaction of albumin with a liver cell surface receptor. These results suggest that the hepatic bilirubin uptake mechanism is one of high affinity which can extract bilirubin from circulating carriers such as albumin, ligandin, or fluorocarbon
Robotic high-throughput purification of affinity-tagged recombinant proteins.
Wiesler, Simone C; Weinzierl, Robert O J
2015-01-01
Affinity purification of recombinant proteins has become the method of choice to obtain good quantities and qualities of proteins for a variety of downstream biochemical applications. While manual or FPLC-assisted purification techniques are generally time-consuming and labor-intensive, the advent of high-throughput technologies and liquid handling robotics has simplified and accelerated this process significantly. Additionally, without the human factor as a potential source of error, automated purification protocols allow for the generation of large numbers of proteins simultaneously and under directly comparable conditions. The delivered material is ideal for activity comparisons of different variants of the same protein. Here, we present our strategy for the simultaneous purification of up to 24 affinity-tagged proteins for activity measurements in biochemical assays. The protocol described is suitable for the scale typically required in individual research laboratories.
Jeeves, Rose E; Mason, Robert P; Woodacre, Alexandra; Cashmore, Annette M
2011-09-01
The pathogenic yeast Candida albicans possesses a reductive iron uptake system which is active in iron-restricted conditions. The sequestration of iron by this mechanism initially requires the reduction of free iron to the soluble ferrous form, which is catalysed by ferric reductase proteins. Reduced iron is then taken up into the cell by a complex of a multicopper oxidase protein and an iron transport protein. Multicopper oxidase proteins require copper to function and so reductive iron and copper uptake are inextricably linked. It has previously been established that Fre10 is the major cell surface ferric reductase in C. albicans and that transcription of FRE10 is regulated in response to iron levels. We demonstrate here that Fre10 is also a cupric reductase and that Fre7 also makes a significant contribution to cell surface ferric and cupric reductase activity. It is also shown, for the first time, that transcription of FRE10 and FRE7 is lower in hyphae compared to yeast and that this leads to a corresponding decrease in cell surface ferric, but not cupric, reductase activity. This demonstrates that the regulation of two virulence determinants, the reductive iron uptake system and the morphological form of C. albicans, are linked. Copyright © 2011 John Wiley & Sons, Ltd.
Removal of radioactive waste waters by calcium phosphate precipitation
International Nuclear Information System (INIS)
Raicevic, S.; Vukovic, Z.; Mandic, M.
1997-01-01
The kinetics of removal of radioactive strontium by coprecipitation and sorption with amorphous calcium phosphate (ACP) which transformed into stable crystalline hydroxyapatite (HA) were investigated. The advantage of phosphate precipitation is a possibility not only for removal of radioactive strontium but also for incorporation of a strontium ion into stable structure of HA. calcium phosphate was precipitated from highly saturated solution by fast reagent mixing. Kinetic experiments were performed using strontium nitrate solution labeled with 8 5 Sr. The amount of radionuclide uptake by the solid phase was determined radiometrically at different time intervals. It was found that ACP phase firmly retains coprecipitated impurities up to 150 min, of reaction time when partial rejection of strontium into the solution occurred. In sorption experiments after prolonged time of equilibrium the firm incorporation of 8 5 Sr stable crystalline structure of HA was detected. The incorporation of 8 5 Sr into crystalline HA was analysed in detail in the paper /S. Raicevic, et. al., J. Radioanal. Nucl. Chem., Articles, Vol. 204, No 2, 1996/ (author)
Energy Technology Data Exchange (ETDEWEB)
Lu, Xia, E-mail: lux2009@lzu.edu.cn; Zhou, Xiao-jiao; Wang, Tie-shan, E-mail: tswang@lzu.edu.cn
2013-11-15
Highlights: • Equilibrium reaches very rapid within 15 min. • pH shift towards neutral indicates release of hydroxyl ions. • High ionic strength inhabits biosorption capacity. • Uptake capacity of heat-killed cells is an order of magnitude higher than live one. • Electrostatic interaction, precipitation, and complexation are the main mechanisms. -- Abstract: Biosorption is of significance for the safety evaluation of high-level nuclear wastes repositories and remediation of radioactive contamination places. Quantitive study and structural characterization of uranium uptake by both live and heat-killed Saccharomyces cerevisiae at environmentally relevant uranium concentration and with different ionic strengths were carried out. Kinetic investigation showed the equilibrium reached within 15 min. In equilibrium studies, pH shift towards neutral indicated release of hydroxyl ions. pH was the most important factor, which partly affected electrostatic interaction between uranyl ions and S. cerevisiae surface. The high ionic strength inhibited biosorption capacity, which can be explained by a competitive reaction between sodium ions and uranyl ions. Heat killing process significantly enhanced biosorption capacity, showing an order of magnitude higher than that of live cells. High resolution transmission electron microscopy (HRTEM) coupled with energy dispersive X-ray (EDX) showed needle-like uranium-phosphate precipitation formed on the cell walls for both live and heat-killed cells. Besides, dark-field micrographs displayed considerable similar uranium-phosphate precipitation presented outside the heat-killed cells. The phosphate released during heat-killing process. FTIR illustrated function groups hydroxyl, carboxyl, phosphate, and amino groups played important role in complexation with uranium.
Preparation of pHEMA-CP composites with high interfacial adhesionvia template-driven mineralization
Energy Technology Data Exchange (ETDEWEB)
Song, Jie; Saiz, Eduardo; Bertozzi, Carolyn R.
2002-12-05
We report a template-driven nucleation and mineral growth process for the high-affinity integration of calcium phosphate (CP) with a poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel scaffold. A mineralization technique was developed that exposes carboxylate groups on the surface of crosslinked pHEMA, promoting high-affinity nucleation and growth of calcium phosphate on the surface along with extensive calcification of the hydrogel interior. External factors such as the heating rate, the agitation of the mineral stock solution and the duration of the process that affect the outcome of the mineralization were investigated. This template-driven mineralization technique provides an efficient approach toward bonelike composites with high mineral-hydrogel interfacial adhesion strength.
International Nuclear Information System (INIS)
Abdalla, A.L.
1992-01-01
With the aim to study the kinetics of radio phosphorus ( 32 P) in the blood of animals supplemented with dicalcium phosphate (BIC), mono ammonium phosphate (MAP), triple superphosphate (SPT) and Tapira rock phosphate (TAP), 32 male sheep were kept in metabolic cages at the Animal Science Section / CENA - USP. Plasma was obtained by centrifugation and the specific activity, rate of disappearance and half life of 32 P in plasma were determined. In the red blood cells were determined the uptake rate of the radioisotope, the rate of disappearance and half life of 32 P up taken. It was observed a statistical significant difference (p 32 P in the plasma and erythrocytes. The specific activity and half life of 32 P in the plasma were statistically different (p<0,10) among sheep receiving the different phosphorus sources; the same was observed in respect to the red blood cells. It was concluded that the supplemented phosphorus source given in the diet of sheep may affect the kinetics of the radio phosphorus in the blood after been intravenously injected. (author)
Directory of Open Access Journals (Sweden)
Claire Godinot
Full Text Available The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO(2 on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata. Three experiments were performed, during 10 days i at three pH(T conditions (8.1, 7.8, and 7.5 and normal temperature (26°C, ii at three temperature conditions (26°, 29°C, and 33°C and normal pH(T (8.1, and iii at three pH(T conditions (8.1, 7.8, and 7.5 and elevated temperature (33°C. After 10 days of incubation, corals had not bleached, as protein, chlorophyll, and zooxanthellae contents were the same in all treatments. However, photosynthetic rates significantly decreased at 33°C, and were further reduced for the pH(T 7.5. The photosynthetic efficiency of PSII was only decreased by elevated temperature. Nutrient uptake rates were not affected by a change in pH alone. Conversely, elevated temperature (33°C alone induced an increase in phosphate uptake but a severe decrease in nitrate and ammonium uptake rates, even leading to a release of nitrogen into seawater. Combination of high temperature (33°C and low pH(T (7.5 resulted in a significant decrease in phosphate and nitrate uptake rates compared to control corals (26°C, pH(T = 8.1. These results indicate that both inorganic nitrogen and phosphorus metabolism may be negatively affected by the cumulative effects of ocean warming and acidification.
Godinot, Claire; Houlbrèque, Fanny
2011-01-01
The effects of ocean acidification and elevated seawater temperature on coral calcification and photosynthesis have been extensively investigated over the last two decades, whereas they are still unknown on nutrient uptake, despite their importance for coral energetics. We therefore studied the separate and combined impacts of increases in temperature and pCO2 on phosphate, ammonium, and nitrate uptake rates by the scleractinian coral S. pistillata. Three experiments were performed, during 10 days i) at three pHT conditions (8.1, 7.8, and 7.5) and normal temperature (26°C), ii) at three temperature conditions (26°, 29°C, and 33°C) and normal pHT (8.1), and iii) at three pHT conditions (8.1, 7.8, and 7.5) and elevated temperature (33°C). After 10 days of incubation, corals had not bleached, as protein, chlorophyll, and zooxanthellae contents were the same in all treatments. However, photosynthetic rates significantly decreased at 33°C, and were further reduced for the pHT 7.5. The photosynthetic efficiency of PSII was only decreased by elevated temperature. Nutrient uptake rates were not affected by a change in pH alone. Conversely, elevated temperature (33°C) alone induced an increase in phosphate uptake but a severe decrease in nitrate and ammonium uptake rates, even leading to a release of nitrogen into seawater. Combination of high temperature (33°C) and low pHT (7.5) resulted in a significant decrease in phosphate and nitrate uptake rates compared to control corals (26°C, pHT = 8.1). These results indicate that both inorganic nitrogen and phosphorus metabolism may be negatively affected by the cumulative effects of ocean warming and acidification. PMID:21949839
Lead iron phosphate glass as a containment medium for disposal of high-level nuclear waste
International Nuclear Information System (INIS)
Boatner, L.A.; Sales, B.C.
1989-01-01
This patent describes lead-iron phosphate glasses containing a high level of Fe 2 O 3 for use as a storage medium for high-level radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste, a highly corrosion resistant, homogeneous, easily processed glass can be formed. For corroding solutions at 90 0 C, with solution pH values in the range between 5 and 9, the corrosion rate of the lead-iron phosphate nuclear waste glass is at least 10 2 to 10 3 times lower than the corrosion rate of a comparable borosilicate nuclear waste glass. The presence of Fe 2 O 3 in forming the lead-iron phosphate glass is critical. The lead-iron phosphate waste glasses can be prepared with minimal modification of the technology developed for processing borosilicate glass nuclear wasteforms
Lumetta, Gregg J; Braley, Jenifer C; Peterson, James M; Bryan, Samuel A; Levitskaia, Tatiana G
2012-06-05
Removing phosphate from alkaline high-level waste sludges at the Department of Energy's Hanford Site in Washington State is necessary to increase the waste loading in the borosilicate glass waste form that will be used to immobilize the highly radioactive fraction of these wastes. We are developing a process which first leaches phosphate from the high-level waste solids with aqueous sodium hydroxide, and then isolates the phosphate by precipitation with calcium oxide. Tests with actual tank waste confirmed that this process is an effective method of phosphate removal from the sludge and offers an additional option for managing the phosphorus in the Hanford tank waste solids. The presence of vibrationally active species, such as nitrate and phosphate ions, in the tank waste processing streams makes the phosphate removal process an ideal candidate for monitoring by Raman or infrared spectroscopic means. As a proof-of-principle demonstration, Raman and Fourier transform infrared (FTIR) spectra were acquired for all phases during a test of the process with actual tank waste. Quantitative determination of phosphate, nitrate, and sulfate in the liquid phases was achieved by Raman spectroscopy, demonstrating the applicability of Raman spectroscopy for the monitoring of these species in the tank waste process streams.
Directory of Open Access Journals (Sweden)
S. Nikmehr
2016-02-01
uptake of Zn in shoot. Conclusion: this study showed that Phosphate solubilizing bacteria (B1 and B2 had significant effects on the growth and nutrient uptake especially phosphorus and zinc in sesame. The simultaneous application of Phosphate rock and Phosphate solubilizing bacteria increased most of the measured parameters similar to the highest levels of triple superphosphate. Therefore, because of high cost of chemical fertilizers production and its environmental problems, application of less levels of phosphorus fertilizers or rock phosphate along with Phosphate solubilizing bacteria could be an appropriate option to avoid wasteful consumption of phosphorus fertilizers.
DEFF Research Database (Denmark)
Trapp, Stefan; Eggen, Trine
2013-01-01
The uptake of the organophosphates tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tributyl phosphate (TBP), the insect repellant N,N-diethyl toluamide (DEET), and the plasticizer n-butyl benzenesulfonamide (NBBS) into plants was studied in greenhouse experiments...
Energy Technology Data Exchange (ETDEWEB)
Johnson, J.L.; Rajagopalan, K.V. (Duke Univ. Medical Center, Durham, NC (USA)); London, R.E. (National Institute of Environmental Health Science, Research Triangle Park, NC (USA))
1989-09-01
The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and {sup 31}P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well.
International Nuclear Information System (INIS)
Johnson, J.L.; Rajagopalan, K.V.; London, R.E.
1989-01-01
The reported presence of covalently bound phosphate residues in flavoproteins has significant implications with regard to the catalytic mechanisms and structural stability of the specific enzymes themselves and in terms of general cellular metabolic regulation. These considerations have led to a reevaluation of the presence of covalently bound phosphorus in the flavoproteins xanthine oxidase and glucose oxidase. Milk xanthine oxidase purified by a procedure that includes anion-exchange chromatography is shown to contain three phosphate residues. All three are noncovalently associated with the protein, two with the FAD cofactor, and one with the molybdenum cofactor. Results of chemical analysis and 31 P NMR spectroscopy indicate that enzyme purified by this method contains no phosphoserine residues. Xanthine oxidase preparations purified by chromatography on calcium phosphate gel in place of DEAE-Sephadex yielded higher phosphate-to-protein ratios, which could be reduced to the expected values by additional purification on a folate affinity column. Highly active, highly purified preparations of glucose oxidase are shown to contain only the two phosphate residues of the FAD cofactor. The covalently bound bridging phosphate reported by others may arise in aged or degraded preparations of the enzyme but appears not to be a constituent of functional glucose oxidase. These results suggest that the presence of covalent phosphate residues in other flavoproteins should be rigorously reevaluated as well
High-affinity hemoglobin and blood oxygen saturation in diving emperor penguins.
Meir, Jessica U; Ponganis, Paul J
2009-10-01
The emperor penguin (Aptenodytes forsteri) thrives in the Antarctic underwater environment, diving to depths greater than 500 m and for durations longer than 23 min. To examine mechanisms underlying the exceptional diving ability of this species and further describe blood oxygen (O2) transport and depletion while diving, we characterized the O2-hemoglobin (Hb) dissociation curve of the emperor penguin in whole blood. This allowed us to (1) investigate the biochemical adaptation of Hb in this species, and (2) address blood O2 depletion during diving, by applying the dissociation curve to previously collected partial pressure of O2 (PO2) profiles to estimate in vivo Hb saturation (SO2) changes during dives. This investigation revealed enhanced Hb-O2 affinity (P50=28 mmHg, pH 7.5) in the emperor penguin, similar to high-altitude birds and other penguin species. This allows for increased O2 at low blood PO2 levels during diving and more complete depletion of the respiratory O2 store. SO2 profiles during diving demonstrated that arterial SO2 levels are maintained near 100% throughout much of the dive, not decreasing significantly until the final ascent phase. End-of-dive venous SO2 values were widely distributed and optimization of the venous blood O2 store resulted from arterialization and near complete depletion of venous blood O2 during longer dives. The estimated contribution of the blood O2 store to diving metabolic rate was low and highly variable. This pattern is due, in part, to the influx of O2 from the lungs into the blood during diving, and variable rates of tissue O2 uptake.
Affinity of four polar neurotransmitters for lipid bilayer membranes
DEFF Research Database (Denmark)
Wang, Chunhua; Ye, Fengbin; Valardez, Gustavo F.
2011-01-01
. The simulations suggest that this attraction mainly relies on electrostatic interactions of the amino group of the neurotransmitter and the lipid phosphate. We conclude that moderate attraction to lipid membranes occurs for some polar neurotransmitters and hence that one premise for a theory of bilayer-mediated......Weak interactions of neurotransmitters and the lipid matrix in the synaptic membrane have been hypothesized to play a role in synaptic transmission of nerve signals, particularly with respect to receptor desensitization (Cantor, R. S. Biochemistry 2003, 42, 11891). The strength of such interactions......, however, was not measured, and this is an obvious impediment for further evaluation and understanding of a possible role for desensitization. We have used dialysis equilibrium to directly measure the net affinity of selected neurotransmitters for lipid membranes and analyzed this affinity data...
Properties and structure of high erbium doped phosphate glass for short optical fibers amplifiers
International Nuclear Information System (INIS)
Seneschal, Karine; Smektala, Frederic; Bureau, Bruno; Floch, Marie Le; Jiang Shibin; Luo, Tao; Lucas, Jacques; Peyghambarian, Nasser
2005-01-01
New phosphate glasses have been developed in order to incorporate high rare-earth ions concentrations. These glasses present a great chemical stability and a high optical quality. The phosphate glass network is open, very flexible, with a linkage of the tetrahedrons very disordered and contains a larger number of non-bridging oxygens (66%). The great stability and resistance against crystallization associated with the possibility to incorporate high doping concentration of rare-earth ions in these phosphate glasses make them very good candidates for the realization of ultra short single mode amplifiers with a high gain at 1.55 μm
DEFF Research Database (Denmark)
Vorum, H; Pedersen, A O; Honoré, B
1992-01-01
Binding equilibria for decanoate to a defatted, commercially available human serum albumin preparation were investigated by dialysis exchange rate determinations. The binding isotherm could not be fitted by the general binding equation. It was necessary to assume that the preparation was a mixture...... of two albumin components about 40% of the albumin having high affinity and about 60% having low affinity. By affinity chromatography we succeeded in purifying the low-affinity component from the mixture. The high-affinity component, however, could not be isolated. We further analyzed the fatty acid...... and drug binding abilities of the low-affinity component. The fatty acids decanoate, laurate, myristate and palmitate were bound with higher affinity to the mixture than to the low-affinity component. Diazepam was bound with nearly the same affinity to the low-affinity component as to the albumin mixture...
Characteristics of high affinity and low affinity adenosine binding sites in human cerebral cortex
International Nuclear Information System (INIS)
John, D.; Fox, I.V.
1986-01-01
The binding characteristics of human brain cortical membrane fractions were evaluated to test the hypothesis that there are A 1 and A 2 adenosine binding sites. The ligands used were 2-chloro(8- 3 H) adenosine and N 6 -(adenine-2, 8- 3 H) cyclohexayladenosine. Binding of chloroadenosine to human brain cortical membranes was time dependent, reversible and concentration dependent. The kinetic constant determinations from binding studies of the adenosine receptor are presented. Utilizing tritium-cyclohexyladenosine as ligand the authors observed evidence for a high affinity binding site in human brain cortical membranes with a kd of 5 nM
International Nuclear Information System (INIS)
Corradino, R.A.
1979-01-01
Either vitamin D 3 (or 1 α,25-(OH) 2 -D 3 ) or hydrocortisone (HC) stimulated phosphate accumulation by organ-cultured embryonic chick duodenum. In combination, these two steroids stimulated phosphate uptake synergistically. Phosphate accumulation appeared to be independent of other vitamin D 3 -stimulated processes: CaBP concentration, cAMP concentration, or alkaline phosphataseactivity. L-phenylalanine, a reported alkaline phosphate inhibitor, when added to the culture medium progressively inhibited either D 3 - or HC-stimulated phosphate uptake subsequent to culture, but did not inhibit the synergistic action under these conditions L-phenylalanine had no consistent effect on alkaline phosphotase activity but unexpectedly, greatly inhibited vitamin D 3 - stimulated CaBP concentration, but only in the absence of HC. Some limited suggestion of an intestinal phosphoprotein sensitve to either vitamin D 3 or HC was observed. (orig.) [de
Dietary phosphorus burden increases cariogenesis independent of vitamin D uptake.
Goodson, J Max; Shi, Ping; Mumena, Chrispinus H; Haq, Afrozul; Razzaque, Mohammed S
2017-03-01
An association between excessive sugar consumption and dental decay, particularly in children, has been well-established. In this study we have analyzed whether consumption of phosphorus, an important ingredient of sugary drinks, has any association with the evolvement of dental decay. Food consumption, gingival redness and dental decay were evaluated in a total of 8,317 children with the mean age of 9.99+0.68 years with a strong gender bias (pdiet, low in sugar but high in phosphorus (6.58%, n=661), compared to those who consumed a low sugar and low phosphorus containing diet (5.02%, n=413). Finally, we did not find any significant association between vitamin D uptake and the genesis of dental decay. From these results, we concluded that both high sugar and high phosphate consumption can influence evolvement of dental decay, and that, a healthier diet could be achieved by reducing consumption of dental cariogenic dietary factors, sugar and phosphate. Copyright © 2016 Elsevier Ltd. All rights reserved.
Characterization of high-affinity (/sup 3/H)ouabain binding in the rat central nervous system
Energy Technology Data Exchange (ETDEWEB)
Hauger, R.; Luu, H.M.; Meyer, D.K.; Goodwin, F.K.; Paul, S.M.
1985-06-01
The characteristics of (/sup 3/H)ouabain binding were examined in various areas of rat brain. In the striatum, Scatchard analysis revealed a single class of high-affinity binding sites with an apparent binding affinity (KD) of 10.4 +/- 0.9 nM and an estimated binding capacity (Bmax) of 7.6 +/- 1.9 pmol/mg protein. Similar monophasic Scatchard plots were found in the brainstem, cerebellum, hypothalamus, and frontal cerebral cortex. (/sup 3/H)Ouabain binding to rat brain was sodium- and ATP-dependent and strongly inhibited by potassium. Proscillariden A was the most potent cardiac glycoside tested in inhibiting specific (/sup 3/H)ouabain binding to brain membranes, and the rank order of inhibitory potencies for a series of cardiac glycosides was similar to that previously reported for inhibition of heart Na,K-ATPase. To assess whether the high-affinity binding sites for (/sup 3/H)ouabain were localized to neuronal or nonneuronal membranes, the effect of discrete kainic acid lesions on striatal (/sup 3/H)ouabain binding was examined. Kainic acid lesions of the striatum reduced (/sup 3/H)ouabain binding to striatal homogenates by 79.6 +/- 1.6%. This suggests that the high-affinity (/sup 3/H)ouabain binding sites measured in our experiments are localized to neuronal elements. Thus, the high-affinity binding of (/sup 3/H)ouabain to brain membranes may selectively label a neuronal form or conformation of Na,K-ATPase.
A proposed chemical mechanism for biological phosphate removal ...
African Journals Online (AJOL)
This paper presents an alternative for the ";all biological"; phosphate removal model. It is postulated that a chemical substance in wastewater reacts with orthophosphate under anaerobic conditions to make the so-called luxury uptake of phosphorus possible in biological nutrient removal (BNR) activated sludge plants.
Huber, M; Pelletier, J G; Torossian, K; Dionne, P; Gamache, I; Charest-Gaudreault, R; Audette, M; Poulin, R
1996-11-01
We have synthesized 2,2'-dithiobis(N-ethyl-spermine-5-carboxamide) (DESC), its thiol monomer (MESC), and the mixed MESC-cysteamine disulfide (DEASC) as potential inhibitors of polyamine transport in mammalian cells. DESC was the most potent antagonist of spermine transport in ZR-75-1 human breast cancer cells, with Ki values of 5. 0 +/- 0.7, 80 +/- 31, and 16 +/- 3 microM for DESC, MESC, and DEASC, respectively. DESC also strongly blocked putrescine and spermidine uptake in ZR-75-1 cells (Ki = 1.6 +/- 0.5 and 2.7 +/- 1.1 microM, respectively). While DESC and MESC were purely competitive inhibitors of putrescine transport, DEASC was a mixed competitive/noncompetitive antagonist. Remarkably, DESC was virtually impermeant in ZR-75-1 cells despite its low Ki toward polyamine transport. The marked difference in affinity between DESC and MESC was essentially due to the tail-to-tail juxtaposition of two spermine-like structures, suggesting that dimeric ligands of the polyamine transporter might simultaneously interact with more than one binding site. While DESC strongly decreased the initial rate of [3H]spermidine transport, even a 40-fold molar excess of antagonist could not completely abolish intracellular spermidine accumulation. Moreover, as little as 0.3 microM spermidine fully restored growth in ZR-75-1 cells treated with an inhibitor of polyamine biosynthesis in the presence of 50 microM DESC, thus emphasizing the importance of uptake of trace amounts of exogenous polyamines. Thus, reducing the exogenous supply of polyamines with a potent competitive inhibitor may be kinetically inadequate to block replenishment of the polyamine pool in polyamine-depleted tumor cells that display high transport capacity. These results demonstrate that polyamine analogues cross-linked into a dimeric structure such as DESC interact with high affinity with the mammalian polyamine carrier without being used as substrates. These novel properties provide a framework for the design of
Selective high-affinity polydentate ligands and methods of making such
Energy Technology Data Exchange (ETDEWEB)
Denardo, Sally J.; Denardo, Gerald L.; Balhorn, Rodney L.
2018-02-06
This invention provides novel polydentate selective high affinity ligands (SHALs) that can be used in a variety of applications in a manner analogous to the use of antibodies. SHALs typically comprise a multiplicity of ligands that each bind different region son the target molecule. The ligands are joined directly or through a linker thereby forming a polydentate moiety that typically binds the target molecule with high selectivity and avidity.
High-aluminum-affinity silica is a nanoparticle that seeds secondary aluminosilicate formation.
Directory of Open Access Journals (Sweden)
Ravin Jugdaohsingh
Full Text Available Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7 we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP. Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m(2 g(-1 and it competes effectively with transferrin for Al(III binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III species binding monomeric silica to form early phase, non-toxic aluminosilicates.
High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation
Jugdaohsingh, Ravin; Brown, Andy; Dietzel, Martin; Powell, Jonathan J.
2013-01-01
Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m2 g-1 and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates. PMID:24349573
Balancing Water Uptake and Loss through the Coordinated Regulation of Stomatal and Root Development.
Directory of Open Access Journals (Sweden)
Christopher Hepworth
Full Text Available Root development is influenced by nutrient and water availabilities. Plants are able to adjust many attributes of their root in response to environmental signals including the size and shape of the primary root, lateral roots and root hairs. Here we investigated the response of roots to changes in the levels of leaf transpiration associated with altered stomatal frequency. We found that plants with high stomatal density and conductance produce a larger rooting area and as a result have enhanced phosphate uptake capacity whereas plants with low stomatal conductance produce a smaller root. Manipulating the growth environment of plants indicated that enhanced root growth is most likely a result of an increased demand for water rather than phosphate. Plants manipulated to have an increase or reduction in root hair growth show a reduction or increase respectively, in stomatal conductance and density. Our results demonstrate that plants can balance their water uptake and loss through coordinated regulation of both stomatal and root development.
Directory of Open Access Journals (Sweden)
Ramon Wahl
2010-02-01
Full Text Available Plant pathogenic fungi cause massive yield losses and affect both quality and safety of food and feed produced from infected plants. The main objective of plant pathogenic fungi is to get access to the organic carbon sources of their carbon-autotrophic hosts. However, the chemical nature of the carbon source(s and the mode of uptake are largely unknown. Here, we present a novel, plasma membrane-localized sucrose transporter (Srt1 from the corn smut fungus Ustilago maydis and its characterization as a fungal virulence factor. Srt1 has an unusually high substrate affinity, is absolutely sucrose specific, and allows the direct utilization of sucrose at the plant/fungal interface without extracellular hydrolysis and, thus, without the production of extracellular monosaccharides known to elicit plant immune responses. srt1 is expressed exclusively during infection, and its deletion strongly reduces fungal virulence. This emphasizes the central role of this protein both for efficient carbon supply and for avoidance of apoplastic signals potentially recognized by the host.
Directory of Open Access Journals (Sweden)
S Rahimzadeh
2013-08-01
Full Text Available In order to investigation the effect of different fertilization treatments on nutrient and essential oil contents in dragonhead drug (Dracocephalum moldavica L., an experiment was conducted in the station of agricultural research in Urmia on 2008. Treatments (nitroxin, barvar phosphate biofertilizer, biosulfur, nitroxin+ barvar phosphate biofertilizer, barvar phosphate biofertilizer + biosulfur, nitroxin+ biosulfur, nitroxin+ barvar phosphate biofertilizer + biosulfur, chemical fertilizer, control were arranged based on randomized complete block design with 4 replications. Results indicated that uptake of Nitrogen, Phosphorus, Potassium, Iron, Copper, Manganese and essential oil content were affected by studied treatments significantly but uptake of zinc by plant was not affected. Means comparison showed the highest values of Nitrogen (3.55%, Potassium (3.47% and Iron (4.56 ppm in Nitroxin treatment, Phosphorus (0.26% and Copper (0.33 ppm in barvar phosphate biofertilizer + biosulfur treatment, Manganese (0.48 ppm in chemical origin of nitrogen+phosphorus+ potassium treatment and essential oil content (0.48% in nitroxin+ barvar phosphate biofertilizer + biosulfur treatment
Taphonomy and affinity of an enigmatic Silurian vertebrate, Jamoytius kerwoodi White
Sansom, Robert S.; Freedman, Kim; Gabbott, Sarah E.; Aldridge, Richard J.; Purnell, Mark A.
2010-01-01
The anatomy and affinities of Jamoytius kerwoodi White have long been controversial, because its complex taphonomy makes unequivocal interpretation impossible with the methodology used in previous studies. Topological analysis, model reconstruction and elemental analysis, followed by anatomical interpretation, allow features to be identified more rigorously and support the hypothesis that Jamoytius is a jawless vertebrate. The preserved features of Jamoytius include W-shaped phosphatic scales...
International Nuclear Information System (INIS)
Pino, I.; Parada, A.M.; Zapata, F.; Navia, M.; Luzio, W.
2002-01-01
The intensification of the agricultural production in Southern Chile demand the application of P fertilizers to volcanic ash soils for optimum plant growth and crop yields. Due to the high P sorption capacities of these soils, high amounts of water-soluble phosphatic fertilizers need to be applied. Therefore, the direct application of locally available Bahia Inglesa phosphate rock has been utilized to supply P to crops in these acid soils. Phosphate rock is a very efficient P input for crops with long growth cycles or crop rotations nevertheless water-soluble P fertilizers must still be applied to crops of short growth cycle. Combined with these strategic P inputs, the use of acid-tolerant and P-efficient genotypes can further contribute to agricultural sustainability. Greenhouse studies were undertaken to explore and identify genotypic variations in P efficiency of wheat grown in Andisols of Southern Chile. 32 P isotopic techniques were utilized to measure the uptake of P from triple superphosphate, a water-soluble P fertilizer and the locally available Bahia Inglesa phosphate rock. Substantial genotypic variations in P use efficiency were found among the Chilean wheat genotypes tested. The utilization of the 32 P isotopic techniques enabled to quantify the P taken up from the P fertilizer and the assessment of differences among the genotypes. Significant genotypic differences were obtained in the P uptake from the local phosphate rock Bahia Inglesa. Much higher applications of phosphate rock were required in Santa Barbara soil series (Andisol) due to its high P retention. A sustainable strategy for agricultural production in the Andisols of Chile would therefore, be the combined utilization of those efficient wheat genotypes and the local phosphate rock Bahia Inglesa. As P efficiency is a multi-faceted trait, which interacts with a range of environmental factors, further field-testing and validation is required accompanied by in depth studies to assess the
Increased muscle glucose uptake after exercise
DEFF Research Database (Denmark)
Richter, Erik; Ploug, Thorkil; Galbo, Henrik
1985-01-01
responsiveness of glucose uptake was noted only in controls. Analysis of intracellular glucose-6-phosphate, glucose, glycogen synthesis, and glucose transport suggested that the exercise effect on responsiveness might be due to enhancement of glucose disposal. After electrical stimulation of diabetic...... of glucose. At maximal insulin concentrations, the enhancing effect of exercise on glucose uptake may involve enhancement of glucose disposal, an effect that is probably less in muscle from diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)......It has recently been shown that insulin sensitivity of skeletal muscle glucose uptake and glycogen synthesis is increased after a single exercise session. The present study was designed to determine whether insulin is necessary during exercise for development of these changes found after exercise...
DEFF Research Database (Denmark)
Persson, Morten; Madsen, Jacob; Østergaard, Søren
2012-01-01
, uPAR binding affinity and cell uptake were determined. To characterize the in vivo properties, dynamic microPET imaging was carried out in nude mice bearing human glioma U87MG tumor xenograft. RESULTS: In vitro experiments revealed uPAR binding affinities in the lower nM range for both conjugated......-AE105-NH(2) was observed. Good stability in phosphate-buffered saline and mouse plasma was observed. High cell uptake was found for both tracers in U87MG tumor cells. Dynamic microPET imaging demonstrated good tumor-to-background ratio for both tracers. Tumor uptake was 2.1% ID/g and 1.3% ID/g 30 min...... positron emission tomography (PET) in human cancer xenograft mice models. Here we introduce (68)Ga-DOTA-AE105-NH(2) and (68)Ga-NODAGA-AE105-NH(2) and evaluate their imaging properties using small-animal PET. METHODS: Synthesis of DOTA-AE105-NH(2) and NODAGA-AE105-NH(2) was based on solid-phase peptide...
Diagnostic significance of /sup 99m/tc-marked phosphate uptake in the soft tissues of the breast
Energy Technology Data Exchange (ETDEWEB)
Bostel, F.; Meybier, H.
1981-03-01
A patient with a right-sided carcinoma of the breast had a bone scintigram with sup(99m)Tc-methylendisphosphonate (sup(99m)Tc-MDP), which showed intensive uptake in the abnormal breast; a year after mastectomy, similar high uptake of the drug was found in the remaining breast. The radiological findings indicated a fibrocystic mastopathy without evidence of malignancy in the left breast. A review of the literature suggested that uptake of osteotropic polyphosphate compounds in the breast was of considerable significance, indicating incipient or developing malignancy. A review of our own cases cast considerable doubt on this interpretation. It is probable that MDP uptake in the breast depends in part on the hormonal pattern and may occasionally be observed during oestrogen therapy in the male (e.g. carcinoma of the prostate).
International Nuclear Information System (INIS)
Poat, J.A.; Cripps, H.E.; Iversen, L.L.
1988-01-01
Forskolin labelled with [ 3 H] bound to high- and low-affinity sites in the rat brain. The high-affinity site was discretely located, with highest densities in the striatum, nucleus accumbens, olfactory tubercule, substantia nigra, hippocampus, and the molecular layers of the cerebellum. This site did not correlate well with the distribution of adenylate cyclase. The high-affinity striatal binding site may be associated with a stimulatory guanine nucleotide-binding protein. Thus, the number of sites was increased by the addition of Mg 2+ and guanylyl imidodiphosphate. Cholera toxin stereotaxically injected into rat striatum increased the number of binding sites, and no further increase was noted following the subsequent addition of guanyl nucleotide. High-affinity forskolin binding sites in non-dopamine-rich brain areas (hippocampus and cerebullum) were modulated in a qualitatively different manner by guanyl nucleotides. In these areas the number of binding sites was significantly reduced by the addition of guanyl nucleotide. These results suggest that forskolin may have a potential role in identifying different functional/structural guanine nucleotide-binding proteins
Hatayama, Masayoshi; Sato, Takahiko; Shinoda, Kozo; Inoue, Chihiro
2011-03-01
The physiological responses of the arsenic-hyperaccumulator, Pteris vittata, such as arsenic uptake and chemical transformation in the fern, have been investigated. However, a few questions remain regarding arsenic treatment in hydroponics. Incubation conditions such as aeration, arsenic concentration, and incubation period might affect those responses of P. vittata in hydroponics. Arsenite uptake was low under anaerobic conditions, as previously reported. However, in an arsenite uptake experiment, phosphorous (P) starvation-dependent uptake of arsenate was observed under aerobic conditions. Time course-dependent analysis of arsenite oxidation showed that arsenite was gradually oxidized to arsenate during incubation. Arsenite oxidation was not observed in any of the control conditions, such as exposure to a nutrient solution or to culture medium only, or with the use of dried root; arsenite oxidation was only observed when live root was used. This result suggests that sufficient aeration allows the rhizosphere system to oxidize arsenite and enables the fern to efficiently take up arsenite as arsenate. X-ray absorption near edge structure (XANES) analyses showed that long-duration exposure to arsenic using a hydroponic system led to the accumulation of arsenate as the dominant species in the root tips, but not in the whole roots, partly because up-regulation of arsenate uptake by P starvation of the fern was caused and retained by long-time incubation. Analysis of concentration-dependent arsenate uptake by P. vittata showed that the uptake switched from a high-affinity transport system to a low-affinity system at high arsenate concentrations, which partially explains the increased arsenate abundance in the whole root. Copyright © 2010 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
Wensveen, Felix M; van Gisbergen, Klaas P J M; Eldering, Eric
2012-09-01
Lymphocyte activation via the antigen receptor is associated with radical shifts in metabolism and changes in requirements for nutrients and cytokines. Concomitantly, drastic changes occur in the expression of pro-and anti-apoptotic proteins that alter the sensitivity of lymphocytes to limiting concentrations of key survival factors. Antigen affinity is a primary determinant for the capacity of activated lymphocytes to access these vital resources. The shift in metabolic needs and the variable access to key survival factors is used by the immune system to eliminate activated low-affinity cells and to generate an optimal high-affinity response. In this review, we focus on the control of apoptosis regulators in activated lymphocytes by nutrients, cytokines, and costimulation. We propose that the struggle among individual clones that leads to the formation of high-affinity effector cell populations is in effect an 'invisible' fourth signal required for effective immune responses. © 2012 John Wiley & Sons A/S.
Energy Technology Data Exchange (ETDEWEB)
Kratz, Sylvia, E-mail: sylvia.kratz@jki.bund.de; Schick, Judith; Schnug, Ewald
2016-01-15
68 rock phosphates and 162 P containing (organo-)mineral fertilizers sold in Germany were evaluated with regard to trace element contents. While Al, As, B, Be, Cd, Cr, Mo, Ni, Pb, Sb, Se, Tl, U, and Zn were higher in sedimentary than in igneous rock phosphates, the opposite was true for Co, Cu, Sn, Mn, Ti, Fe, and Sr. Comparing element concentrations to the currently valid legal limit values defined by the German Fertilizer Ordinance, it was found that some PK and many straight P fertilizers (superphosphate, triple superphosphate, partly acidulated rock phosphates) exceeded the limit of 50 mg Cd/kg P{sub 2}O{sub 5}. Mean values for As, Ni, Pb, and Tl remained below legal limits in almost all cases. While no legal limit has been defined for U in Germany yet, the limit of 50 mg U/kg P{sub 2}O{sub 5} for P containing fertilizers proposed by the German Commission for the Protection of Soils was clearly exceeded by mean values for all fertilizer types analyzed. A large share of the samples evaluated in this work contained essential trace elements at high concentrations, with many of them not being declared as such. Furthermore, trace elements supplied with these fertilizers at a fertilization rate leveling P uptake would exceed trace element uptake by crops. This may become most relevant for B and Fe, since many crops are sensitive to an oversupply of B, and Fe loads exceeding plant uptake may immobilize P supplies for the crops by forming Fe phosphate salts. The sample set included two products made from thermochemically treated sewage sludge ash. The products displayed very high concentrations of Fe and Mn and exceeded the legal limit for Ni, emphasizing the necessity to continue research on heavy metal removal from recycled raw materials and the development of environmentally friendly and agriculturally efficient fertilizer products. - Highlights: • Mineral fertilizers (MF) sold in Germany often exceed legal limits for Cd • MF sold in Germany contain high
Energy Technology Data Exchange (ETDEWEB)
Jung, K. H.; Kim, D. H.; Paik, J. Y.; Koh, B. H.; Bae, J. S.; Choe, Y. S.; Lee, K. H.; Kim, B. T. [Samsung Medical Center, Seoul (Korea, Republic of)
2005-07-01
Some of the obstacles for the clinical application of whole nerve growth factor (NGF) may be overcome by utilizing small molecule mimetics. We thus investigated the in vivo pharmacokinetics and biodistribution of a small cyclic peptide derived from NGF-[C(92-96)] with high receptor binding affinity. I-125 C(92-96) was labeled with the Bolton-Hunter method, and binding to TrkA/IgG chimeric protein was confirmed on a polyacrylamide gel after cross-linking. Pharmacokinetic analysis was performed in normal ICR mice intravenously injected with 0.5 MBq I-125 C(92-96) containing varying doses of C(92-96). Biodistribution studies were done at 6 h after injection. Cross-linkage analysis confirmed binding of I-125 C(92-96) to the high affinity NGF receptor, TrkA. Intravenously injected I-125 C(92-96) was cleared from the blood in a biexponential manner with an early T1/2{alpha} of 5.2 min and late T1/2{beta} of 121.3 min. Log blood-concentration decreased over time with a k-slope of 0.0025, clearance of 11.8{+-}0.5 ml/min, T1/2 of 4.1{+-}0.4 hr, and volume of distribution of 69.7{+-}4.6 ml. The pattern of elimination from the blood remained essentially unchanged regardless of the dose of added C(92-96), with dose-proportionate increases in AUCs and peak concentrations consistent with linear pharmacokinetics. Biodistribution studies demonstrated high kidney activity suggesting renal excretion of I-125 C(92-96). There were moderate levels of accumulation in the spleen, lungs and liver, followed by the myocardium and skeletal muscle, whereas brain uptake was low (< 0.2 %ID/gm). Intravenously administered C(92-96) follows linear pharmacokinetics, and is cleared from the circulation at a rate comparable to whole NGF despite its substantially smaller size. Although intravenous C(92-96) does not adequately reach brain tissue, clinically relevant doses can achieve major organ accumulation levels that may be sufficient to elicit biologic responses through NGF receptors.
International Nuclear Information System (INIS)
Jung, K. H.; Kim, D. H.; Paik, J. Y.; Koh, B. H.; Bae, J. S.; Choe, Y. S.; Lee, K. H.; Kim, B. T.
2005-01-01
Some of the obstacles for the clinical application of whole nerve growth factor (NGF) may be overcome by utilizing small molecule mimetics. We thus investigated the in vivo pharmacokinetics and biodistribution of a small cyclic peptide derived from NGF-[C(92-96)] with high receptor binding affinity. I-125 C(92-96) was labeled with the Bolton-Hunter method, and binding to TrkA/IgG chimeric protein was confirmed on a polyacrylamide gel after cross-linking. Pharmacokinetic analysis was performed in normal ICR mice intravenously injected with 0.5 MBq I-125 C(92-96) containing varying doses of C(92-96). Biodistribution studies were done at 6 h after injection. Cross-linkage analysis confirmed binding of I-125 C(92-96) to the high affinity NGF receptor, TrkA. Intravenously injected I-125 C(92-96) was cleared from the blood in a biexponential manner with an early T1/2α of 5.2 min and late T1/2β of 121.3 min. Log blood-concentration decreased over time with a k-slope of 0.0025, clearance of 11.8±0.5 ml/min, T1/2 of 4.1±0.4 hr, and volume of distribution of 69.7±4.6 ml. The pattern of elimination from the blood remained essentially unchanged regardless of the dose of added C(92-96), with dose-proportionate increases in AUCs and peak concentrations consistent with linear pharmacokinetics. Biodistribution studies demonstrated high kidney activity suggesting renal excretion of I-125 C(92-96). There were moderate levels of accumulation in the spleen, lungs and liver, followed by the myocardium and skeletal muscle, whereas brain uptake was low (< 0.2 %ID/gm). Intravenously administered C(92-96) follows linear pharmacokinetics, and is cleared from the circulation at a rate comparable to whole NGF despite its substantially smaller size. Although intravenous C(92-96) does not adequately reach brain tissue, clinically relevant doses can achieve major organ accumulation levels that may be sufficient to elicit biologic responses through NGF receptors
Uranium uptake by hydroponically cultivated crop plants
Energy Technology Data Exchange (ETDEWEB)
Soudek, Petr; Petrova, Sarka [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic); Benesova, Dagmar [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic); Faculty of Environment Technology, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Dvorakova, Marcela [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic); Vanek, Tomas, E-mail: vanek@ueb.cas.cz [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR, v.v.i. and Crop Research Institute, v.v.i., Rozvojova 263, 162 05 Prague 6 (Czech Republic)
2011-06-15
Hydroponicaly cultivated plants were grown on medium containing uranium. The appropriate concentrations of uranium for the experiments were selected on the basis of a standard ecotoxicity test. The most sensitive plant species was determined to be Lactuca sativa with an EC{sub 50} value about 0.1 mM. Cucumis sativa represented the most resistant plant to uranium (EC{sub 50} = 0.71 mM). Therefore, we used the uranium in a concentration range from 0.1 to 1 mM. Twenty different plant species were tested in hydroponic solution supplemented by 0.1 mM or 0.5 mM uranium concentration. The uranium accumulation of these plants varied from 0.16 mg/g DW to 0.011 mg/g DW. The highest uranium uptake was determined for Zea mays and the lowest for Arabidopsis thaliana. The amount of accumulated uranium was strongly influenced by uranium concentration in the cultivation medium. Autoradiography showed that uranium is mainly localized in the root system of the plants tested. Additional experiments demonstrated the possibility of influencing the uranium uptake from the cultivation medium by amendments. Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba up to 2.8 times or 1.9 times, respectively. Phosphate deficiency increased uranium uptake up to 4.5 times or 3.9 times, respectively, by Brassica oleracea and S. alba. In the case of deficiency of iron or presence of cadmium ions we did not find any increase in uranium accumulation. - Highlights: > The uranium accumulation in twenty different plant species varied from 0.160 to 0.011 mg/g DW. > Uranium is mainly localized in the root system. > Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba. > The phosphates deficiency increase the uranium uptake.
Uranium uptake by hydroponically cultivated crop plants
International Nuclear Information System (INIS)
Soudek, Petr; Petrova, Sarka; Benesova, Dagmar; Dvorakova, Marcela; Vanek, Tomas
2011-01-01
Hydroponicaly cultivated plants were grown on medium containing uranium. The appropriate concentrations of uranium for the experiments were selected on the basis of a standard ecotoxicity test. The most sensitive plant species was determined to be Lactuca sativa with an EC 50 value about 0.1 mM. Cucumis sativa represented the most resistant plant to uranium (EC 50 = 0.71 mM). Therefore, we used the uranium in a concentration range from 0.1 to 1 mM. Twenty different plant species were tested in hydroponic solution supplemented by 0.1 mM or 0.5 mM uranium concentration. The uranium accumulation of these plants varied from 0.16 mg/g DW to 0.011 mg/g DW. The highest uranium uptake was determined for Zea mays and the lowest for Arabidopsis thaliana. The amount of accumulated uranium was strongly influenced by uranium concentration in the cultivation medium. Autoradiography showed that uranium is mainly localized in the root system of the plants tested. Additional experiments demonstrated the possibility of influencing the uranium uptake from the cultivation medium by amendments. Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba up to 2.8 times or 1.9 times, respectively. Phosphate deficiency increased uranium uptake up to 4.5 times or 3.9 times, respectively, by Brassica oleracea and S. alba. In the case of deficiency of iron or presence of cadmium ions we did not find any increase in uranium accumulation. - Highlights: → The uranium accumulation in twenty different plant species varied from 0.160 to 0.011 mg/g DW. → Uranium is mainly localized in the root system. → Tartaric acid was able to increase uranium uptake by Brassica oleracea and Sinapis alba. → The phosphates deficiency increase the uranium uptake.
Fraisier, V; Gojon, A; Tillard, P; Daniel-Vedele, F
2000-08-01
The NpNRT2.1 gene encodes a putative inducible component of the high-affinity nitrate (NO3-) uptake system in Nicotiana plumbaginifolia. Here we report functional and physiological analyses of transgenic plants expressing the NpNRT2.1 coding sequence fused to the CaMV 35S or rolD promoters. Irrespective of the level of NO3- supplied, NO3- contents were found to be remarkably similar in wild-type and transgenic plants. Under specific conditions (growth on 10 mM NO3-), the steady-state NpNRT2. 1 mRNA level resulting from the deregulated transgene expression was accompanied by an increase in 15NO3- influx measured in the low concentration range. This demonstrates for the first time that the NRT2.1 sequence codes a limiting element of the inducible high-affinity transport system. Both 15NO3- influx and mRNA levels decreased in the wild type after exposure to ammonium, in agreement with previous results from many species. Surprisingly, however, influx was also markedly decreased in transgenic plants, despite stable levels of transgene expression in independent transformants after ammonium addition. We conclude that the conditions associated with the supply of a reduced nitrogen source such as ammonium, or with the generation of a further downstream metabolite, probably exert a repressive effect on NO3- influx at both transcriptional and post-transcriptional levels.
Detection of Waterborne Viruses Using High Affinity Molecularly Imprinted Polymers.
Altintas, Zeynep; Gittens, Micah; Guerreiro, Antonio; Thompson, Katy-Anne; Walker, Jimmy; Piletsky, Sergey; Tothill, Ibtisam E
2015-07-07
Molecularly imprinted polymers (MIPs) are artificial receptor ligands which can recognize and specifically bind to a target molecule. They are more resistant to chemical and biological damage and inactivation than antibodies. Therefore, target specific-MIP nanoparticles are aimed to develop and implemented to biosensors for the detection of biological toxic agents such as viruses, bacteria, and fungi toxins that cause many diseases and death due to the environmental contamination. For the first time, a molecularly imprinted polymer (MIP) targeting the bacteriophage MS2 as the template was investigated using a novel solid-phase synthesis method to obtain the artificial affinity ligand for the detection and removal of waterborne viruses through optical-based sensors. A high affinity between the artificial ligand and the target was found, and a regenerative MIP-based virus detection assay was successfully developed using a new surface plasmon resonance (SPR)-biosensor which provides an alternative technology for the specific detection and removal of waterborne viruses that lead to high disease and death rates all over the world.
Arabidopsis pdr2 reveals a phosphate-sensitive checkpoint in root development.
Ticconi, Carla A; Delatorre, Carla A; Lahner, Brett; Salt, David E; Abel, Steffen
2004-03-01
Plants have evolved complex strategies to maintain phosphate (Pi) homeostasis and to maximize Pi acquisition when the macronutrient is limiting. Adjustment of root system architecture via changes in meristem initiation and activity is integral to the acclimation process. However, the mechanisms that monitor external Pi status and interpret the nutritional signal remain to be elucidated. Here, we present evidence that the Pi deficiency response, pdr2, mutation disrupts local Pi sensing. The sensitivity and amplitude of metabolic Pi-starvation responses, such as Pi-responsive gene expression or accumulation of anthocyanins and starch, are enhanced in pdr2 seedlings. However, the most conspicuous alteration of pdr2 is a conditional short-root phenotype that is specific for Pi deficiency and caused by selective inhibition of root cell division followed by cell death below a threshold concentration of about 0.1 mm external Pi. Measurements of general Pi uptake and of total phosphorus (P) in root tips exclude a defect in high-affinity Pi acquisition. Rescue of root meristem activity in Pi-starved pdr2 by phosphite (Phi), a non-metabolizable Pi analog, and divided-root experiments suggest that pdr2 disrupts sensing of low external Pi availability. Thus, PDR2 is proposed to function at a Pi-sensitive checkpoint in root development, which monitors environmental Pi status, maintains and fine-tunes meristematic activity, and finally adjusts root system architecture to maximize Pi acquisition.
Production and Identification of High Affinity Monoclonal Antibodies Against Pesticide Carbofuran
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
To produce high-affinity monoclonal antibodies against pesticide carbofuran, and the develop immunochemical assays for people's health and environmental protection, the hapten 4-[[(2,3-dihydro-2,2-dimethyl-7-benzofuranyloxy) carbonyl]-amino]-butanoic acid (BFNB) of carbofuran was synthesized and Balb/c mice were immunized by the hapten-carrier (BFNB-bovine serum albumin, BFNB-BSA) conjugates. The splenocytes of immunized mice were fused with Sp2/0 cells and the cultural supernatants of hybridoma cells were screened by the indirect enzyme-linked immunoabsorbent assay (ELISA), based on BFNB-ovoalbumin conjugates (BFNB-OVA). Purified monoclonal antibody (McAb) was obtained from fluids of ascites, deposited by octanoic acid and ammonium sulfate. The affinity and the specificity of McAb were characterized by ELISA or indirect competitive ELISA. A hybridoma cell line (5D3) secreting anti-carbofuran McAb had been established. The titer of culture medium and ascites was up to 1:2.048 × 103 and 1:1.024 × 106, respectively, and the subtype of the McAb was IgG1. The affinity constant of the McAb was about 2.54 × 109 L mol-1, with an IC50 value of 1.18 ng mL-1 and a detection limit of 0.01 ng mL-1. Cross-reactivity studies showed that the McAb was quiet specific for carbofuran, as among the four analogous compounds, they were all hardly recognized (4.59 × 10-4% for 2,3-dihydro-2,2-dimethyl-7-benzofuranol and less than 3.0 × 10-4% for others). The prepared McAb had a very high affinity and specificity,and it could be used to develop ELISA for rapid determination of carbofuran.
Isoguvacine binding, uptake, and release: relation to the GABA system
Energy Technology Data Exchange (ETDEWEB)
White, W F; Snodgrass, S R
1983-06-01
Isoguvacine (1,2,3,6-tetrahydropyridine-4-carboxylic acid) is a GABA (gamma-aminobutyric acid) agonist with limited conformational flexibility. In these studies we investigated the binding, uptake, and release of (3H) isoguvacine by use of tissue preparations of rat CNS, comparing the results with similar studies of (3H)GABA. The results from these investigations indicate that isoguvacine binds to membrane preparations of rat forebrain with pharmacological characteristics similar to the post-synaptic GABA recognition site; that it is transported into synaptosomal preparations by an uptake system similar to the high-affinity GABA uptake system; and that recently accumulated isoguvacine is released in a Ca2+-dependent manner and by heteroexchange with external GABA. The ability of isoguvacine and gamma-hydroxybutyric acid to decrease the K+-stimulated Ca2+-dependent release process was also investigated. The results indicate that isoguvacine interactions have many of the biochemical features of GABA synaptic function, isoguvacine being, however, less potent than GABA.
Sphagnum mosses--masters of efficient N-uptake while avoiding intoxication.
Fritz, Christian; Lamers, Leon P M; Riaz, Muhammad; van den Berg, Leon J L; Elzenga, Theo J T M
2014-01-01
Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 µM), N-form ((15)N-ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (Km 3.5-6.5 µM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term N-uptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands.
Sphagnum Mosses - Masters of Efficient N-Uptake while Avoiding Intoxication
Fritz, Christian; Lamers, Leon P. M.; Riaz, Muhammad; van den Berg, Leon J. L.; Elzenga, Theo J. T. M.
2014-01-01
Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 µM), N-form (15N - ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (Km 3.5–6.5 µM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term N-uptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands
Lead iron phosphate glass as a containment medium for disposal of high-level nuclear waste
Boatner, Lynn A.; Sales, Brian C.
1989-01-01
Lead-iron phosphate glasses containing a high level of Fe.sub.2 O.sub.3 for use as a storage medium for high-level radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste, a highly corrosion resistant, homogeneous, easily processed glass can be formed. For corroding solutions at 90.degree. C., with solution pH values in the range between 5 and 9, the corrosion rate of the lead-iron phosphate nuclear waste glass is at least 10.sup.2 to 10.sup.3 times lower than the corrosion rate of a comparable borosilicate nuclear waste glass. The presence of Fe.sub.2 O.sub.3 in forming the lead-iron phosphate glass is critical. Lead-iron phosphate nuclear waste glass can be prepared at temperatures as low as 800.degree. C., since they exhibit very low melt viscosities in the 800.degree. to 1050.degree. C. temperature range. These waste-loaded glasses do not readily devitrify at temperatures as high as 550.degree. C. and are not adversely affected by large doses of gamma radiation in H.sub.2 O at 135.degree. C. The lead-iron phosphate waste glasses can be prepared with minimal modification of the technology developed for processing borosilicate glass nuclear wasteforms.
DEFF Research Database (Denmark)
Grønlund, Mette; Albrechtsen, Merete Tryde; Johansen, Ida Elisabeth
2013-01-01
Arbuscular mycorrhizal fungi (AMF) have a key role in plant phosphate (Pi) uptake by their efficient capture of soil phosphorus (P) that is transferred to the plant via Pi transporters in the root cortical cells. The activity of this mycorrhizal Pi uptake pathway is often associated with downregu......Arbuscular mycorrhizal fungi (AMF) have a key role in plant phosphate (Pi) uptake by their efficient capture of soil phosphorus (P) that is transferred to the plant via Pi transporters in the root cortical cells. The activity of this mycorrhizal Pi uptake pathway is often associated...... with downregulation of Pi transporter genes in the direct Pi uptake pathway. As the total Pi taken up by the plant is determined by the combined activity of mycorrhizal and direct pathways, it is important to understand the interplay between these, in particular the actual activity of the pathways. To study...
Biggio, G; Concas, A; Corda, M G; Serra, M
1989-02-28
The effect of zolpidem, an imidazopyridine derivative with high affinity at the type I benzodiazepine recognition site, on the function of the GABAA/ionophore receptor complex was studied in vitro. Zolpidem, mimicking the action of diazepam, increased [3H]GABA binding, enhanced muscimol-stimulated 36Cl- uptake and reduced [35S]TBPS binding in rat cortical membrane preparations. Zolpidem was less effective than diazepam on the above parameters. Zolpidem induced a lower increase of [3H]GABA binding (23 vs. 35%) and muscimol-stimulated 36Cl- uptake (22 vs. 40%) and a smaller decrease of [35S]TBPS binding (47 vs. 77%) than diazepam. The finding that zolpidem enhanced the function of GABAergic synapses with an efficacy qualitatively and quantitatively different from that of diazepam suggests that this compound is a partial agonist at the benzodiazepine recognition site. Thus, our results are consistent with the view that the biochemical and pharmacological profile of a benzodiazepine recognition site ligand reflects its efficacy to enhance GABAergic transmission. Whether the preferential affinity of zolpidem at the type I site is involved in its atypical biochemical and pharmacological profile remains to be clarified.
A rhodium(III) complex for high-affinity DNA base-pair mismatch recognition
Junicke, Henrik; Hart, Jonathan R.; Kisko, Jennifer; Glebov, Oleg; Kirsch, Ilan R.; Barton, Jacqueline K.
2003-01-01
A rhodium(III) complex, rac-[Rh(bpy)2phzi]3+ (bpy, 2,2′-bipyridine; phzi, benzo[a]phenazine-5,6-quinone diimine) has been designed as a sterically demanding intercalator targeted to destabilized mismatched sites in double-helical DNA. The complex is readily synthesized by condensation of the phenazine quinone with the corresponding diammine complex. Upon photoactivation, the complex promotes direct strand scission at single-base mismatch sites within the DNA duplex. As with the parent mismatch-specific reagent, [Rh(bpy)2(chrysi)]3+ [chrysene-5,6-quinone diimine (chrysi)], mismatch selectivity depends on the helix destabilization associated with mispairing. Unlike the parent chrysi complex, the phzi analogue binds and cleaves with high affinity and efficiency. The specific binding constants for CA, CC, and CT mismatches within a 31-mer oligonucleotide duplex are 0.3, 1, and 6 × 107 M−1, respectively; site-specific photocleavage is evident at nanomolar concentrations. Moreover, the specificity, defined as the ratio in binding affinities for mispaired vs. well paired sites, is maintained. The increase in affinity is attributed to greater stability in the mismatched site associated with stacking by the heterocyclic aromatic ligand. The high-affinity complex is also applied in the differential cleavage of DNA obtained from cell lines deficient in mismatch repair vs. those proficient in mismatch repair. Agreement is found between photocleavage by the mismatch-specific probes and deficiency in mismatch repair. This mismatch-specific targeting, therefore, offers a potential strategy for new chemotherapeutic design. PMID:12610209
Heat- and exercise-induced hyperthermia: effects on high-energy phosphates.
Francesconi, R; Mager, M
1979-08-01
To assess the role of high-energy phosphate compounds in the etiology of heat injury with respect to the release of intracellular constituents, the susceptibility of selected tissues to heat injury, and the shock-like demise of the animals, rats were exercised on a treadmill (9.14 m/min) in a hot environment (34.5-35 degrees C) to a rectal temperature (Tre) of 42.5-43 degrees C. In the heart, kidney, left lateral lobe of the liver, and gastrocnemius muscle extricated from animals immediately upon termination of the treadmill run, levels of glucose-6-phosphate (G-6-P), adenosine triphosphate (ATP), and creatine phosphate (CP) were unchanged when compared with sedentary controls. In animals which had been resuscitated by infusion of isotonic saline into a jugular catheter, levels of CP were significantly (p less than 0.025) elevated in gastrocnemius muscle. In rats which were unconscious and succumbing to the effects of hyperthermic injury, levels of hepatic G-6-P and ATP were significantly reduced (p less than 0.05, p less than 0.02, respectively). These results indicate that the combination of exhaustive excercise/heat injury had the most deleterious effects upon hepatic metabolism. However, while resuscitation with physiological saline may be accompanied by an increased synthesis of CP, hyperthermic exhaustion and the concomitant efflux of cellular constituents cannot be attributed to a depletion or even a decrement of high-energy phosphates in vital tissues.
Drenkova-Tuhtan, Asya; Mandel, Karl; Paulus, Anja; Meyer, Carsten; Hutter, Frank; Gellermann, Carsten; Sextl, Gerhard; Franzreb, Matthias; Steinmetz, Heidrun
2013-10-01
An innovative nanocomposite material is proposed for phosphate recovery from wastewater using magnetic assistance. Superparamagnetic microparticles modified with layered double hydroxide (LDH) ion exchangers of various compositions act as phosphate adsorbers. Magnetic separation and chemical regeneration of the particles allows their reuse, leading to the successful recovery of phosphate. Based upon the preliminary screening of different LDH ion exchanger modifications for phosphate selectivity and uptake capacity, MgFe-Zr LDH coated magnetic particles were chosen for further characterization and application. The adsorption kinetics of phosphate from municipal wastewater was studied in dependence with particle concentration, contact time and pH. Adsorption isotherms were then determined for the selected particle system. Recovery of phosphate and regeneration of the particles was examined via testing a variety of desorption solutions. Reusability of the particles was demonstrated for 15 adsorption/desorption cycles. Adsorption in the range of 75-97% was achieved in each cycle after 1 h contact time. Phosphate recovery and enrichment was possible through repetitive application of the desorption solution. Finally, a pilot scale experiment was carried out by treating 125 L of wastewater with the particles in five subsequent 25 L batches. Solid-liquid separation on this scale was carried out with a high-gradient magnetic filter (HGMF). Copyright © 2013 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Ana Maria Garcia-Lopez
2015-10-01
Full Text Available The contribution of Trichoderma asperellum T34 to the plant uptake of phosphorus (P from sparingly phytoavailable forms such as insoluble calcium (Ca phosphates and phytates was studied. Two experiments with cucumber (Cucumis sativus L. on siliceous sand were performed involving two factors, namely: (i P source, viz., KH2PO4, phytate (Ins6P, and phosphate rock (PR, and (ii inoculation with T34. Liquid pure cultures of T34 were also used. T34 increased the total content in P of cucumber roots irrespective of the particular P form and enhanced total P uptake by plants with P supplied as Ins6P or PR. The increased phytase activity observed with T34 contributes to explain its favourable influence on the uptake of P supplied as Ins6P. Solubilization of Ca phosphates from PR was favoured by the slightly acidifying effect and the increased organic anion concentration promoted by the fungus in the plant growth media. It can be concluded that T34 can improve P nutrition in plants grown on media containing phytates or insoluble Ca phosphates as dominant P forms.
High blood oxygen affinity in the air-breathing swamp eel Monopterus albus.
Damsgaard, Christian; Findorf, Inge; Helbo, Signe; Kocagoz, Yigit; Buchanan, Rasmus; Huong, Do Thi Thanh; Weber, Roy E; Fago, Angela; Bayley, Mark; Wang, Tobias
2014-12-01
The Asian swamp eel (Monopterus albus, Zuiew 1793) is a facultative air-breathing fish with reduced gills. Previous studies have shown that gas exchange seems to occur across the epithelium of the buccopharyngeal cavity, the esophagus and the integument, resulting in substantial diffusion limitations that must be compensated by adaptations in others steps of the O₂ transport system to secure adequate O₂ delivery to the respiring tissues. We therefore investigated O₂ binding properties of whole blood, stripped hemoglobin (Hb), two major isoHb components and the myoglobin (Mb) from M. albus. Whole blood was sampled using indwelling catheters for blood gas analysis and determination of O₂ equilibrium curves. Hb was purified to assess the effects of endogenous allosteric effectors, and Mb was isolated from heart and skeletal muscle to determine its O₂ binding properties. The blood of M. albus has a high O₂ carrying capacity [hematocrit (Hct) of 42.4±4.5%] and binds O₂ with an unusually high affinity (P₅₀=2.8±0.4mmHg at 27°C and pH7.7), correlating with insensitivity of the Hb to the anionic allosteric effectors that normally decrease Hb-O₂ affinity. In addition, Mb is present at high concentrations in both heart and muscle (5.16±0.99 and 1.08±0.19mg ∙ g wet tissue⁻¹, respectively). We suggest that the high Hct and high blood O₂ affinity serve to overcome the low diffusion capacity in the relatively inefficient respiratory surfaces, while high Hct and Mb concentration aid in increasing the O₂ flux from the blood to the muscles. Copyright © 2014 Elsevier Inc. All rights reserved.
2009-01-01
Background Secondary metabolism in Serratia sp. ATCC 39006 (Serratia 39006) is controlled via a complex network of regulators, including a LuxIR-type (SmaIR) quorum sensing (QS) system. Here we investigate the molecular mechanism by which phosphate limitation controls biosynthesis of two antibiotic secondary metabolites, prodigiosin and carbapenem, in Serratia 39006. Results We demonstrate that a mutation in the high affinity phosphate transporter pstSCAB-phoU, believed to mimic low phosphate conditions, causes upregulation of secondary metabolism and QS in Serratia 39006, via the PhoBR two-component system. Phosphate limitation also activated secondary metabolism and QS in Serratia 39006. In addition, a pstS mutation resulted in upregulation of rap. Rap, a putative SlyA/MarR-family transcriptional regulator, shares similarity with the global regulator RovA (regulator of virulence) from Yersina spp. and is an activator of secondary metabolism in Serratia 39006. We demonstrate that expression of rap, pigA-O (encoding the prodigiosin biosynthetic operon) and smaI are controlled via PhoBR in Serratia 39006. Conclusion Phosphate limitation regulates secondary metabolism in Serratia 39006 via multiple inter-linked pathways, incorporating transcriptional control mediated by three important global regulators, PhoB, SmaR and Rap. PMID:19476633
Directory of Open Access Journals (Sweden)
Everson Lee
2009-05-01
Full Text Available Abstract Background Secondary metabolism in Serratia sp. ATCC 39006 (Serratia 39006 is controlled via a complex network of regulators, including a LuxIR-type (SmaIR quorum sensing (QS system. Here we investigate the molecular mechanism by which phosphate limitation controls biosynthesis of two antibiotic secondary metabolites, prodigiosin and carbapenem, in Serratia 39006. Results We demonstrate that a mutation in the high affinity phosphate transporter pstSCAB-phoU, believed to mimic low phosphate conditions, causes upregulation of secondary metabolism and QS in Serratia 39006, via the PhoBR two-component system. Phosphate limitation also activated secondary metabolism and QS in Serratia 39006. In addition, a pstS mutation resulted in upregulation of rap. Rap, a putative SlyA/MarR-family transcriptional regulator, shares similarity with the global regulator RovA (regulator of virulence from Yersina spp. and is an activator of secondary metabolism in Serratia 39006. We demonstrate that expression of rap, pigA-O (encoding the prodigiosin biosynthetic operon and smaI are controlled via PhoBR in Serratia 39006. Conclusion Phosphate limitation regulates secondary metabolism in Serratia 39006 via multiple inter-linked pathways, incorporating transcriptional control mediated by three important global regulators, PhoB, SmaR and Rap.
Zahra, Zahra; Arshad, Muhammad; Rafique, Rafia; Mahmood, Arshad; Habib, Amir; Qazi, Ishtiaq A; Khan, Saud A
2015-08-12
Application of engineered nanoparticles (NPs) with respect to nutrient uptake in plants is not yet well understood. The impacts of TiO2 and Fe3O4 NPs on the availability of naturally soil-bound inorganic phosphorus (Pi) to plants were studied along with relevant parameters. For this purpose, Lactuca sativa (lettuce) was cultivated on the soil amended with TiO2 and Fe3O4 (0, 50, 100, 150, 200, and 250 mg kg(-1)) over a period of 90 days. Different techniques, such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Raman, and Fourier transform infrared spectroscopy (FTIR) were used to monitor translocation and understand the possible mechanisms for phosphorus (P) uptake. The trends for P accumulation were different for roots (TiO2 > Fe3O4 > control) and shoots (Fe3O4 > TiO2 > control). Cystine and methionine were detected in the rhizosphere in Raman spectra. Affinities of NPs to adsorb phosphate ions, modifications in P speciation, and NP stress in the rhizosphere had possibly contributed to enhanced root exudation and acidification. All of these changes led to improved P availability and uptake by the plants. These promising results can help to develop an innovative strategy for using NPs for improved nutrient management to ensure food security.
Harrigan, P. J.; Trentham, D. R.
1973-01-01
In the presence of NAD+ the acylation by 1,3-diphosphoglycerate of the four active sites of pig muscle d-glyceraldehyde 3-phosphate dehydrogenase can be monitored at 365nm by the disappearance of the absorption band present in the binary complex of NAD+ and the enzyme. A non-specific salt effect decreased the acylation rate 25-fold when the ionic strength was increased from 0.10 to 1.0. This caused acylation to be the rate-limiting process in the enzyme-catalysed reductive dephosphorylation of 1,3-diphosphoglycerate at high ionic strength at pH8. The salt effect permitted investigation of the acylation over a wide range of conditions. Variation of pH from 5.4 to 8.6 produced at most a two-fold change in the acylation rate. One proton was taken up per site acylated at pH8.0. By using a chromophoric H+ indicator the rate of proton uptake could be monitored during the acylation and was also almost invariant in the pH range 5.5–8.5. Transient kinetic studies of the overall enzyme-catalysed reaction indicated that acylation was the process involving proton uptake at pH8.0. The enzyme mechanism is discussed in the light of these results. PMID:4360248
Biosuper as a phosphate fertilizer in a calcareous soil with low ...
African Journals Online (AJOL)
SERVER
2007-06-04
Jun 4, 2007 ... Key words: Zea mays, phosphorus uptake, phosphorus fertilization, corn, Thiobacillus, rock phosphate. ... improve plant nutrients availability in calcareous soils and .... lus elicits the reaction of sulphur with water and oxygen, ...
International Nuclear Information System (INIS)
Worley, Bradley; Sisco, Nicholas J.; Powers, Robert
2015-01-01
NMR ligand-affinity screens are vital to drug discovery, are routinely used to screen fragment-based libraries, and used to verify chemical leads from high-throughput assays and virtual screens. NMR ligand-affinity screens are also a highly informative first step towards identifying functional epitopes of unknown proteins, as well as elucidating the biochemical functions of protein–ligand interaction at their binding interfaces. While simple one-dimensional 1 H NMR experiments are capable of indicating binding through a change in ligand line shape, they are plagued by broad, ill-defined background signals from protein 1 H resonances. We present an uncomplicated method for subtraction of protein background in high-throughput ligand-based affinity screens, and show that its performance is maximized when phase-scatter correction is applied prior to subtraction
Selective induction of high-ouabain-affinity isoform of Na sup + -K sup + -ATPase by thyroid hormone
Energy Technology Data Exchange (ETDEWEB)
Haber, R.S.; Loeb, J.N. (Columbia Univ., New York, NY (USA))
1988-12-01
The administration of thyroid hormone is known to result in an induction of the Na{sup +}-K{sup +}-adenosinetriphosphatase (Na{sup +}-K{sup +}-ATPase) in rat skeletal muscle and other thyroid hormone-responsive tissues. Since the Na{sup +}-K{sup +}-ATPase in a variety of mammalian tissues has recently been reported to exist in at least two forms distinguishable by differing affinities for the inhibitory cardiac glycoside ouabain. The authors have studied the effects of 3,3{prime},5-triiodo-L-thyronine (T{sub 3}) treatment on these two forms of the enzyme in rat diaphragm. The inhibition of Na{sup +}-K{sup +}-ATPase activity in a crude membrane fraction by varying concentrations of ouabain conformed to a biphasic pattern consistent with the presence of two distinct isoforms with inhibition constants (K{sub I}s) for ouabain of {approximately}10{sup {minus}7} and 10{sup {minus}4} M, respectively. Measurement of the specific binding of ({sup 3}H)ouabain to these membranes confirmed the presence of a class of high-affinity ouabain binding sites with a dissociation constant (K{sub d}) of slightly less than 10{sup {minus}7}M, whose maximal binding capacity was increased by T{sub 3} treatment by 185%. Binding studies in unfractionated homogenates of diaphragm similarly demonstrated the presence of high-affinity sites whose maximal binding capacity was increased by T{sub 3} treatment. Quantitation of both the high- and low-ouabain-affinity forms of the Na{sup +}-K{sup +}-ATPase by ouabain-dependent phosphorylation from ({sup 32}P)orthophosphate confirmed that T{sub 3} treatment markedly increased the number of high-affinity sites while having little effect on the number of low-affinity sites. These observations provide, to our knowledge, the first demonstration that these two forms of the Na{sup +}-K{sup +}-ATPase are subject to selective hormonal induction.
Uptake behavior of titanium molybdophosphate for cesium and strontium
International Nuclear Information System (INIS)
Yavari, R.; Ahmadi, S.J.; Huang, Y.D.
2010-01-01
This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at 25 deg C using column packed with H 3 O + form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed out of column by using 4 M NH 4 Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially cesium from nuclear waste solution. (author)
Energy Technology Data Exchange (ETDEWEB)
Wang, Deng-Liang [The First Clinical Medical College of Fujian Medical University, Fuzhou (China); Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou (China); Song, Yan-Ling; Zhu, Zhi; Li, Xi-Lan; Zou, Yuan [State Key Laboratory for Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Chemistry, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Yang, Hai-Tao; Wang, Jiang-Jie [The First Clinical Medical College of Fujian Medical University, Fuzhou (China); Yao, Pei-Sen [Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou (China); Pan, Ru-Jun [The First Clinical Medical College of Fujian Medical University, Fuzhou (China); Yang, Chaoyong James, E-mail: cyyang@xmu.edu.cn [State Key Laboratory for Physical Chemistry of Solid Surfaces, Key Laboratory for Chemical Biology of Fujian Province, Key Laboratory of Analytical Chemistry, and Department of Chemical Biology, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Kang, De-Zhi, E-mail: kdzy99988@163.com [The First Clinical Medical College of Fujian Medical University, Fuzhou (China); Department of Neurosurgery, The First Affiliated Hospital of Fujian Medical University, Fuzhou (China)
2014-10-31
Highlights: • This is the first report of DNA aptamer against EGFR in vitro. • Aptamer can bind targets with high affinity and selectivity. • DNA aptamers are more stable, cheap and efficient than RNA aptamers. • Our selected DNA aptamer against EGFR has high affinity with K{sub d} 56 ± 7.3 nM. • Our selected DNA aptamer against EGFR has high selectivity. - Abstract: Epidermal growth factor receptor (EGFR/HER1/c-ErbB1), is overexpressed in many solid cancers, such as epidermoid carcinomas, malignant gliomas, etc. EGFR plays roles in proliferation, invasion, angiogenesis and metastasis of malignant cancer cells and is the ideal antigen for clinical applications in cancer detection, imaging and therapy. Aptamers, the output of the systematic evolution of ligands by exponential enrichment (SELEX), are DNA/RNA oligonucleotides which can bind protein and other substances with specificity. RNA aptamers are undesirable due to their instability and high cost of production. Conversely, DNA aptamers have aroused researcher’s attention because they are easily synthesized, stable, selective, have high binding affinity and are cost-effective to produce. In this study, we have successfully identified DNA aptamers with high binding affinity and selectivity to EGFR. The aptamer named TuTu22 with K{sub d} 56 ± 7.3 nM was chosen from the identified DNA aptamers for further study. Flow cytometry analysis results indicated that the TuTu22 aptamer was able to specifically recognize a variety of cancer cells expressing EGFR but did not bind to the EGFR-negative cells. With all of the aforementioned advantages, the DNA aptamers reported here against cancer biomarker EGFR will facilitate the development of novel targeted cancer detection, imaging and therapy.
International Nuclear Information System (INIS)
Wang, Deng-Liang; Song, Yan-Ling; Zhu, Zhi; Li, Xi-Lan; Zou, Yuan; Yang, Hai-Tao; Wang, Jiang-Jie; Yao, Pei-Sen; Pan, Ru-Jun; Yang, Chaoyong James; Kang, De-Zhi
2014-01-01
Highlights: • This is the first report of DNA aptamer against EGFR in vitro. • Aptamer can bind targets with high affinity and selectivity. • DNA aptamers are more stable, cheap and efficient than RNA aptamers. • Our selected DNA aptamer against EGFR has high affinity with K d 56 ± 7.3 nM. • Our selected DNA aptamer against EGFR has high selectivity. - Abstract: Epidermal growth factor receptor (EGFR/HER1/c-ErbB1), is overexpressed in many solid cancers, such as epidermoid carcinomas, malignant gliomas, etc. EGFR plays roles in proliferation, invasion, angiogenesis and metastasis of malignant cancer cells and is the ideal antigen for clinical applications in cancer detection, imaging and therapy. Aptamers, the output of the systematic evolution of ligands by exponential enrichment (SELEX), are DNA/RNA oligonucleotides which can bind protein and other substances with specificity. RNA aptamers are undesirable due to their instability and high cost of production. Conversely, DNA aptamers have aroused researcher’s attention because they are easily synthesized, stable, selective, have high binding affinity and are cost-effective to produce. In this study, we have successfully identified DNA aptamers with high binding affinity and selectivity to EGFR. The aptamer named TuTu22 with K d 56 ± 7.3 nM was chosen from the identified DNA aptamers for further study. Flow cytometry analysis results indicated that the TuTu22 aptamer was able to specifically recognize a variety of cancer cells expressing EGFR but did not bind to the EGFR-negative cells. With all of the aforementioned advantages, the DNA aptamers reported here against cancer biomarker EGFR will facilitate the development of novel targeted cancer detection, imaging and therapy
LDL Receptors as Gateways for Intracellular Porphyrin Uptake
International Nuclear Information System (INIS)
Novick, S.; Laster, B.; Quastel, M.
2004-01-01
Boronated compounds are currently being studied for possible use in Boron Neutron Capture Therapy (BNCT). We found that one of these agents, BOPP (tetrakis-carborane-carboxylate, esters of 2,4-bis (a,b- dihydroxyethyl) deuteroporphyrin IX), could also be labeled with indium (In-BOPP) and, therefore, could also be used potentially to transport high Z atoms into tumor cell DNA for AET (Auger Electron Therapy). In order to assess the uptake of these agents into cells, the role of the LDL receptor in the intracellular accumulation of BOPP and In-BOPP was investigated. Pre-incubation of V-79 Chinese hamster cells in medium containing delipidized fetal bovine serum (FBS) markedly increased the subsequent uptake of intracellular boron transported by both BOPP and In-BOPP when compared with cells that had been pre-incubated with medium containing 10% normal FBS (lipidized). The increased uptake was characterized by elevated levels of receptor, and greater affinity was shown for both BOPP and In-BOPP, although less marked with the latter. Positive cooperativity was demonstrated by sigmoid saturation curves, Scatchard analysis and Hill plots. Increasing the amount of LDL in the incubation medium had a relatively small effect on the total accumulation of either indium or boron atoms inside the cell. Furthermore, chemical acetylation of LDL did not decrease the intracellular uptake of either boron or indium transported by BOPP or In-BOPP. It is thus concluded that BOPP and In-BOPP preferentially enter the cells directly by way of the LDL receptor and that only a small fraction of these molecules are transported into the cells indirectly using serum LDLs as their carriers. These data suggest a novel way of bringing greater amounts of boron and indium (and perhaps other agents) into tissues. Porphyrins can be used to transport different agents into tumor cells because they are tumor affinic molecules. Tumors express a higher number of LDL receptors than do most normal tissues
Plant uptake of radionuclides and rhizosphere factors
International Nuclear Information System (INIS)
Arie, Tsutomu; Gouthu, S.; Ambe, Shizuko; Yamaguchi, Isamu; Hirata, Hiroaki
1999-01-01
Influence of soil factors such as nuclide availability, pH, organic carbon, cation exchange capacity (CEC), exchangeable cations (Ca 2+ , Mg 2+ , and K + ), phosphate absorption coefficient (PAC), physical composition of soil (coarse sand, fine sand, silt, and clay), soil texture, and rhizosphere microbes on uptake of radionuclides by plants are studied. (author)
The diagnostic significance of sup(99m)TC-marked phosphate uptake in the soft tissues of the breast
International Nuclear Information System (INIS)
Bostel, F.; Meybier, H.; Heidelberg Univ.
1981-01-01
A patient with a right-sided carcinoma of the breast had a bone scintigram with sup(99m)Tc-methylendisphosphonate (sup(99m)Tc-MDP), which showed intensive uptake in the abnormal breast; a year after mastectomy, similar high uptake of the drug was found in the remaining breast. The radiological findings indicated a fibrocystic mastopathy without evidence of malignancy in the left breast. A review of the literature suggested that uptake of osteotropic polyphosphate compounds in the breast was of considerable significance, indicating incipient or developing malignancy. A review of our own cases cast considerable doubt on this interpretation. It is probable that MDP uptake in the breast depends in part on the hormonal pattern and may occasionally be observed during oestrogen therapy in the male (e.g. carcinoma of the prostate). (orig.) [de
The effects of pH and temperature on phosphate and nitrate uptake ...
African Journals Online (AJOL)
The objective of this study was to ascertain the effects of pH and temperature on nutrient uptake efficiency of 3 wastewater protozoan isolates (Aspidisca (A), Trachelophyllum (B) and Peranema (C)) that have previously been screened for nutrient uptake ability. The study was carried out in shake flask at pH 5, 6, 7, 8 and 9 ...
International Nuclear Information System (INIS)
Rohde, B.H.; Rea, M.A.; Simon, J.R.; McBride, W.J.
1979-01-01
Crude synaptosomal (P 2 ) preparations were obtained from the cerebella of rats in which the granule cell population had been selectively reduced by X-irradiation treatment and from the cerebella of control animals. In the P 2 fraction form control cerebella, the level of glutamate was greater than any other of the 5 amino acids measured and was 2-fold higher than taurine. The content of taurine, GABA, glycine, and alanine were not changed by the X-irradiation treatment. The uptake of 1.0 micrometers-L-[ 3 H]glutamate and L-[ 3 H]aspartate was reduced approx 20% by X-irradiation treatment, whereas the uptake of 1.0 micrometers-[ 3 H]GABA and [ 3 H]taurine was unchanged. In a second study, the uptake of L-[ 3 H]glutamate, L-[ 3 H]aspartate and [ 3 H]GABA was measured using P 2 fractions obtained from the cerebella of rats in which the population of granule, stellate and basket cells had been reduced by X-irradiation treatment. The uptake of 1.0 micrometers-L-[ 3 H]glutamate, L-[ 3 H]aspartate and [ 3 H]GABA was significantly (P < 0.05) reduced to 57.68 and 59% respectively, of control values. The data are discussed in terms of glutamate being the excitatory neurotransmitter released from granule cells and GABA being the inhibitory neurotransmitter released from basket cells. (author)
Energy Technology Data Exchange (ETDEWEB)
Lin, Kun-Yi Andrew, E-mail: linky@nchu.edu.tw [Department of Environmental Engineering, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung, Taiwan (China); Chen, Shen-Yi [Department of Environmental Engineering, National Chung Hsing University, 250 Kuo-Kuang Road, Taichung, Taiwan (China); Jochems, Andrew P. [New Mexico Bureau of Geology & Mineral Resources and New Mexico Institute of Mining & Technology, Socorro, NM (United States)
2015-06-15
Phosphate is one of the most concerning compounds in wastewater streams and a main nutrient that causes eutrophication. To eliminate the phosphate pollution, Metal Organic Frameworks (MOFs) are proposed in this study as adsorbents to remove phosphate from water. The zirconium-based MOF, UiO-66, was selected as representative MOF given its exceptional stability in water. To investigate the effect of an amine functional group, UiO-66-NH2 was also prepared using an amine-substituted ligand. The adsorption kinetics and isotherm reveal that UiO-66-NH2 exhibited higher adsorption capacities than UiO-66 possibly due to the amine group. However, the interaction between phosphate and zirconium sites of UiO MOFs might be the primary factor accounting for the phosphate adsorption to UiO MOFs. UiO MOFs also exhibited a high selectivity towards phosphate over other anions such as bromate, nitrite and nitrate. Furthermore, UiO MOFs were found to adsorb phosphate and to completely remove diluted phosphate in urine. We also found that UiO MOFs could be easily regenerated and re-used for phosphate adsorption. These findings suggest that UiO MOFs can be effective and selective adsorbents to remove phosphate from water as well as urine. - Highlights: • UiO-66 as the first type of MOFs was used to remove phosphate from water and urine. • The amine group in UiO MOFs was found to enhance the phosphate adsorption. • UiO-66 exhibited a high adsorption selectivity towards phosphate over other anions. • UiO-66 could be easily regenerated and re-used with 85% regeneration efficiency.
Lead-iron phosphate glass: a stable storage medium for high-level nuclear waste
International Nuclear Information System (INIS)
Sales, B.C.; Boatner, L.A.
1984-01-01
Results are presented which show that lead-iron phosphate glasses are a promising new waste form for the safe immobilization of both high-level defense and high-level commercial radioactive waste. Relative to the borosilicate nuclear waste glasses that are currently the ''reference'' waste form for the long-term disposal of nuclear waste, lead-iron phosphate glasses have several distinct advantages: (1) an aqueous corrosion rate that is about 1000 times lower, (2) a processing temperature that is 100 0 to 250 0 C lower and, (3) a much lower melt viscosity in the temperature range from 800 0 to 1000 0 C. Most significantly, the lead-iron phosphate waste form can be processed using a technology similar to that developed for borosilicate nuclear waste glasses
Lead-iron phosphate glass as a containment medium for the disposal of high-level nuclear wastes
Boatner, L.A.; Sales, B.C.
1984-04-11
Disclosed are lead-iron phosphate glasses containing a high level of Fe/sub 2/O/sub 3/ for use as a storage medium for high-level radioactive nuclear waste. By combining lead-iron phosphate glass with various types of simulated high-level nuclear waste
International Nuclear Information System (INIS)
Hutchens, T.W.; Li, C.M.; Zamah, N.M.; Besch, P.K.
1987-01-01
The steroid binding function of soluble (cytosolic) estrogen receptors from calf uteri was evaluated under conditions known to modify the extent of hydrophobic interaction with receptor-associated proteins. Receptor preparations were equilibrated into 6 M urea buffers and control buffers by chromatography through small columns of Sephadex G-25 or by dialysis at 0.6 0 C. Equilibrium dissociation constants (K/sub d/) and binding capacities (n) of experimental and control receptor preparations were determined by 13-point Scatchard analyses using concentrations of 17β-[ 3 H]estradiol from 0.05 to 10 nM. Nonspecific binding was determined at each concentration by parallel incubations with a 200-fold molar excess of the receptor-specific competitor diethylstilbestrol. The control receptor population was consistently found to be a single class of binding sites with a high affinity for estradiol which was unaffected by G-25 chromatography, by dialysis, by dilution, or by the presence of 0.4 M KCl. However, equilibration into 6 M urea induced a discrete (10-fold) reduction in receptor affinity to reveal a second, thermodynamically stable, high-affinity binding state. The presence of 0.4 M KCl did not significantly influence the discrete change in receptor affinity induced by urea. The effects of urea on both receptor affinity and binding capacity were reversible, suggesting a lack of covalent modification. These results demonstrate nonenzymatic means by which not only the binding capacity but also the affinity of receptor for estradiol can be reversibly controlled, suggesting that high concentrations of urea might be more effectively utilized during the physicochemical characterization and purification of steroid receptor proteins
Energy Technology Data Exchange (ETDEWEB)
Van As, J A
1991-03-01
The mechanism and nature of zinc uptake was studied with the aid of {sup 65}Zn. Uptake of zinc was also compared to that of potassium and phosphate, which are known to be ATP-dependent. Zinc uptake was characterized by a rapid initial uptake, followed by a slower linear phase. Decreasing the temperature from 25 to 2 deg C resulted in a decrease of only 30% in the rate of zinc uptake. Uptake of zinc was insensitive to DNP - possibly indicating the non-metabolic nature of the uptake process. A possible role for zinc in protein synthesis could not be demonstrated as CHI did not inhibit zinc uptake. Cyanide reduced zinc uptake to almost zero, possibly due to complexation of zinc by cyanide. Light had no effect on the accumulation of Zn, whereas dark incubation reduced potassium uptake substantially. The relative high rate of zinc uptake and the passive nature of the uptake process might be due to the high binding capacity of the free space for zinc ions. Transport of the zinc in the xylem and phloem of intact bean plants, as well as the metabolic dependence of the latter, was also investigated. The bulk of the zinc absorbed by bean plants remained in the roots and stems with only a very small fraction being translocated to shoots. Adsorption was the major uptake mechanism in roots and stems. In contrast to transport in the xylem, zinc was readily transported in the phloem. Loading and unloading of zinc in the phloem was not influenced by low temperature or DNP. Opposed to this, loading of potassium and phosphate was inhibited by DNP, while unloading was inhibited by low temperature. It can therefore be concluded that the uptake and transport of zinc is probably a passive process. 33 figs., 282 refs.
Brain tumor initiating cells adapt to restricted nutrition through preferential glucose uptake.
Flavahan, William A; Wu, Qiulian; Hitomi, Masahiro; Rahim, Nasiha; Kim, Youngmi; Sloan, Andrew E; Weil, Robert J; Nakano, Ichiro; Sarkaria, Jann N; Stringer, Brett W; Day, Bryan W; Li, Meizhang; Lathia, Justin D; Rich, Jeremy N; Hjelmeland, Anita B
2013-10-01
Like all cancers, brain tumors require a continuous source of energy and molecular resources for new cell production. In normal brain, glucose is an essential neuronal fuel, but the blood-brain barrier limits its delivery. We now report that nutrient restriction contributes to tumor progression by enriching for brain tumor initiating cells (BTICs) owing to preferential BTIC survival and to adaptation of non-BTICs through acquisition of BTIC features. BTICs outcompete for glucose uptake by co-opting the high affinity neuronal glucose transporter, type 3 (Glut3, SLC2A3). BTICs preferentially express Glut3, and targeting Glut3 inhibits BTIC growth and tumorigenic potential. Glut3, but not Glut1, correlates with poor survival in brain tumors and other cancers; thus, tumor initiating cells may extract nutrients with high affinity. As altered metabolism represents a cancer hallmark, metabolic reprogramming may maintain the tumor hierarchy and portend poor prognosis.
Nguyen, Hai T; Guiard, Bruno P; Bacq, Alexandre; David, Denis J; David, Indira; Quesseveur, Gaël; Gautron, Sophie; Sanchez, Connie; Gardier, Alain M
2013-01-01
BACKGROUND AND PURPOSE Escitalopram, the S(+)-enantiomer of citalopram is the most selective 5-HT reuptake inhibitor approved. Although all 5-HT selective reuptake inhibitors (SSRIs) increase extracellular levels of 5-HT ([5-HT]ext). some also enhance, to a lesser extent, extracellular levels of noradrenaline ([NA]ext). However, the mechanisms by which SSRIs activate noradrenergic transmission in the brain remain to be determined. EXPERIMENTAL APPROACH This study examined the effects of escitalopram, on both [5-HT]ext and [NA]ext in the frontal cortex (FCx) of freely moving wild-type (WT) and mutant mice lacking the 5-HT transporter (SERT−/−) by using intracerebral microdialysis. We explored the possibilities that escitalopram enhances [NA]ext, either by a direct mechanism involving the inhibition of the low- or high-affinity noradrenaline transporters, or by an indirect mechanism promoted by [5-HT]ext elevation. The forced swim test (FST) was used to investigate whether enhancing cortical [5-HT]ext and/or [NA]ext affected the antidepressant-like activity of escitalopram. KEY RESULTS In WT mice, a single systemic administration of escitalopram produced a significant increase in cortical [5-HT]ext and [NA]ext. As expected, escitalopram failed to increase cortical [5-HT]ext in SERT−/− mice, whereas its neurochemical effects on [NA]ext persisted in these mutants. In WT mice subjected to the FST, escitalopram increased swimming parameters without affecting climbing behaviour. Finally, escitalopram, at relevant concentrations, failed to inhibit cortical noradrenaline and 5-HT uptake mediated by low-affinity monoamine transporters. CONCLUSIONS AND IMPLICATIONS These experiments suggest that escitalopram enhances, although moderately, cortical [NA]extin vivo by a direct mechanism involving the inhibition of the high-affinity noradrenaline transporter (NET). PMID:22233336
NK1 receptor fused to beta-arrestin displays a single-component, high-affinity molecular phenotype.
Martini, Lene; Hastrup, Hanne; Holst, Birgitte; Fraile-Ramos, Alberto; Marsh, Mark; Schwartz, Thue W
2002-07-01
Arrestins are cytosolic proteins that, upon stimulation of seven transmembrane (7TM) receptors, terminate signaling by binding to the receptor, displacing the G protein and targeting the receptor to clathrin-coated pits. Fusion of beta-arrestin1 to the C-terminal end of the neurokinin NK1 receptor resulted in a chimeric protein that was expressed to some extent on the cell surface but also accumulated in transferrin-labeled recycling endosomes independently of agonist stimulation. As expected, the fusion protein was almost totally silenced with respect to agonist-induced signaling through the normal Gq/G11 and Gs pathways. The NK1-beta-arrestin1 fusion construct bound nonpeptide antagonists with increased affinity but surprisingly also bound two types of agonists, substance P and neurokinin A, with high, normal affinity. In the wild-type NK1 receptor, neurokinin A (NKA) competes for binding against substance P and especially against antagonists with up to 1000-fold lower apparent affinity than determined in functional assays and in homologous binding assays. When the NK1 receptor was closely fused to G proteins, this phenomenon was eliminated among agonists, but the agonists still competed with low affinity against antagonists. In contrast, in the NK1-beta-arrestin1 fusion protein, all ligands bound with similar affinity independent of the choice of radioligand and with Hill coefficients near unity. We conclude that the NK1 receptor in complex with arrestin is in a high-affinity, stable, agonist-binding form probably best suited to structural analysis and that the receptor can display binding properties that are nearly theoretically ideal when it is forced to complex with only a single intracellular protein partner.
Enevoldsen, Lotte Hahn; Heaf, James; Højgaard, Liselotte; Zerahn, Bo; Hasbak, Philip
2017-03-01
In bone scan patients with dialysis-treated chronic kidney disease (CKD) and hyperparathyroidism, soft tissue accumulation of technetium-99 m hydroxy/methylene diphosphonate (Tc-99 m-HDP/MDP) has been reported primarily in case reports and usually explained by hypercalcaemia and/or hyperphosphataemia. As human vascular smooth muscle cells produce hydroxyapatite during cell culture with increased phosphate levels and as Tc-99 m-HDP/MDP primarily binds to hydroxyapatite, we hypothesized that soft tissue accumulation would be found in patients with hyperphosphataemia. We identified 63 CKD patients diagnosed with secondary hyperparathyroidism admitted for Tc-99 m-HDP bone scan. Baseline characteristics and mean concentrations of biochemical markers (including P-calcium and P-phosphate) taken 0-3 months prior to the bone scans were collected. Soft tissue uptake was detected on bone scans in 37 of 63 (59%) patients. Primary locations were in the heart (27/37 = 73%), muscles (12/37 = 32%), lung (9/37 = 24%) and gastrointestinal tract (6/37 = 16%), and 13 of 37 (35%) patients had simultaneous uptake in more than one location. Regarding biochemical markers, patients with soft tissue uptake only differed from patients without in terms of plasma phosphate levels (1·95 ± 0·15 (n = 37) versus 1·27 ± 0·08 (n = 26), P = 0·0012). All patients with myocardial uptake (n = 27) had a coronary arteriography-verified history of coronary artery disease (CAD), whereas CAD was only present in six of the 36 patients without myocardial uptake. In conclusion, dialysis-treated CKD patients with secondary hyperparathyroidism have a high incidence of soft tissue uptake, and this finding is strongly correlated with elevated phosphate, but not calcium values. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.
Estimation of readily-available phosphate in some English Lake District woodland soils
International Nuclear Information System (INIS)
Harrison, A.F.
1975-01-01
Four chemical extraction methods (2.5 percent acetic acid, Olsen, Truog and Egner) and 5 isotope dilution methods involving short exchange periods (1 inverse dilution, 2 carrier-free and 2 using phosphate carrier) were investigatd for reliability in measurement of readily-available phosphate in widely differing soils from some non-fertilized semi-natural Lake District woodlands. Correlation coefficients between values produced and phosphate uptake during a two-month period from 16 soils (pH range 3.85 to 7.85) by Urtica dioica L., a phosphate-sensitive plant, differed markedly. They were negative for all the extraction procedures, varying from r = -0.079 for the Truog method to -0.518 for the Olsen method. The isotope dilution methods, with the exception of one, all gave positive correlation coefficients, varying from r = -0.676 for the carrier-free method of Talibudeen to r = 0.798 for a modified Amer carrier method. When combined by multiple regression analysis, the results of the isotope dilution methods accounted for 86.4 percent of the variation in phosphate-uptake by the nettle plants, whereas the results of the four extraction methods accounted for only 32.2 percent. Multiple regression analysis of the data showed that there were strong and different interactions between all methods investigated and soil properties, particularly soil pH, organic matter content, extractable iron, C/P and C/N. This clearly indicates that methods must be evaluated for each series of soils to be compared. (author)
The high-affinity peptidoglycan binding domain of Pseudomonas phage endolysin KZ144
Energy Technology Data Exchange (ETDEWEB)
Briers, Yves [Division of Gene Technology, Department of Biosystems, Katholieke Universiteit Leuven, Kasteelpark Arenberg 21, B-3001 Leuven (Belgium); Schmelcher, Mathias; Loessner, Martin J. [Institute of Food Science and Nutrition, ETH Zuerich, Schmelzbergstrasse 7, CH-8092 Zuerich (Switzerland); Hendrix, Jelle; Engelborghs, Yves [Laboratory of Biomolecular Dynamics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200G, B-3001 Leuven (Belgium); Volckaert, Guido [Division of Gene Technology, Department of Biosystems, Katholieke Universiteit Leuven, Kasteelpark Arenberg 21, B-3001 Leuven (Belgium); Lavigne, Rob, E-mail: rob.lavigne@biw.kuleuven.be [Division of Gene Technology, Department of Biosystems, Katholieke Universiteit Leuven, Kasteelpark Arenberg 21, B-3001 Leuven (Belgium)
2009-05-29
The binding affinity of the N-terminal peptidoglycan binding domain of endolysin KZ144 (PBD{sub KZ}), originating from Pseudomonas aeruginosa bacteriophage {phi}KZ, has been examined using a fusion protein of PBD{sub KZ} and green fluorescent protein (PBD{sub KZ}-GFP). A fluorescence recovery after photobleaching analysis of bound PBD{sub KZ}-GFP molecules showed less than 10% fluorescence recovery in the bleached area within 15 min. Surface plasmon resonance analysis confirmed this apparent high binding affinity revealing an equilibrium affinity constant of 2.95 x 10{sup 7} M{sup -1} for the PBD{sub KZ}-peptidoglycan interaction. This unique domain, which binds to the peptidoglycan of all tested Gram-negative species, was harnessed to improve the specific activity of the peptidoglycan hydrolase domain KMV36C. The chimeric peptidoglycan hydrolase (PBD{sub KZ}-KMV36C) exhibits a threefold higher specific activity than the native catalytic domain (KMV36C). These results demonstrate that the modular assembly of functional domains is a rational approach to improve the specific activity of endolysins from phages infecting Gram-negatives.
Niazi, Nabeel Khan; Bibi, Irshad; Fatimah, Ayesha; Shahid, Muhammad; Javed, Muhammad Tariq; Wang, Hailong; Ok, Yong Sik; Bashir, Safdar; Murtaza, Behzad; Saqib, Zulfiqar Ahmad; Shakoor, Muhammad Bilal
2017-07-03
In this study, we examined the potential role of phosphate (P; 0, 50, 100 mg kg -1 ) on growth, gas exchange attributes, and photosynthetic pigments of Brassica napus and Brassica juncea under arsenic (As) stress (0, 25, 50, 75 mg kg -1 ) in a pot experiment. Results revealed that phosphate supplementation (P100) to As-stressed plants significantly increased shoot As concentration, dry biomass yield, and As uptake, in addition to the improved morphological and gas exchange attributes and photosynthetic pigments over P0. However, phosphate-assisted increase in As uptake was substantially (up to two times) greater for B. napus, notably due to higher shoot As concentration and dry biomass yield, compared to B. juncea at the P100 level. While phosphate addition in soil (P100) led to enhanced shoot As concentration in B. juncea, it reduced shoot dry biomass, primarily after 50 and 75 mg kg -1 As treatments. The translocation factor and bioconcentration factor values of B. napus were higher than B. juncea for all As levels in the presence of phosphate. This study demonstrates that phosphate supplementation has a potential to improve As phytoextraction efficiency, predominantly for B. napus, by minimizing As-induced damage to plant growth, as well as by improving the physiological and photosynthetic attributes.
Plant uptake of radionuclides and rhizosphere factors
Energy Technology Data Exchange (ETDEWEB)
Arie, Tsutomu; Gouthu, S.; Ambe, Shizuko; Yamaguchi, Isamu [Institute of Physical and Chemical Research, Wako, Saitama (Japan); Hirata, Hiroaki
1999-03-01
Influence of soil factors such as nuclide availability, pH, organic carbon, cation exchange capacity (CEC), exchangeable cations (Ca{sup 2+}, Mg{sup 2+}, and K{sup +}), phosphate absorption coefficient (PAC), physical composition of soil (coarse sand, fine sand, silt, and clay), soil texture, and rhizosphere microbes on uptake of radionuclides by plants are studied. (author)
International Nuclear Information System (INIS)
Orito, N; Umekage, S; Sakai, E; Tanaka, T; Kikuchi, Y; Sato, K; Kawauchi, S; Tanaka, H
2012-01-01
We have developed a modified SELEX (systematic evolution of ligands by exponential enrichment) method to obtain RNA aptamers with high affinity to C-reactive protein (CRP). CRP is a clinical biomarker present in plasma, the level of which increases in response to infections and noninfectious inflammation. The CRP level is also an important prognostic indicator in patients with several syndromes. At present, CRP content in blood is measured immunochemically using antibodies. To develop a more sensitive method using RNA aptamers, we have attempted to obtain high-affinity RNA aptamers to CRP. We succeeded in obtaining an RNA aptamer with high affinity to CRP using a CRP-immobilized Sepharose column and pre-elution procedure. Pre-elution is a method that removes the weak binding portion from a selected RNA population by washing for a short time with buffer containing CRP. By surface plasmon-resonance (SPR) analysis, the affinity constant of this aptamer for CRP was calculated to be K D = 2.25x10 -9 (M). The secondary structure, contact sites with CRP protein, and application of this aptamer will be described.
Evaluating the effectiveness of phosphate fertilizers in some Venezuelan soils
International Nuclear Information System (INIS)
Casanova, E.; Salas, A.M.; Toro, M.
2002-01-01
In Venezuela, 70% of the soils are acid with low natural fertility where phosphorus is the most limiting element together with nitrogen and potassium for plant growth. The efficiency of phosphate fertilization is low. Greenhouse and field experiments were conducted to evaluate the efficiency of natural and modified rock phosphate using conventional and isotopic techniques. An incubation experiment was done to measure changes in available P on application of different phosphate fertilizers at a constant rate of 100 mg P/kg in ten acid soils of agricultural importance in Venezuela. In the greenhouse, two experiments were conducted to relate P fixation to soil P availability and the response of an index plant (Agrostis sp.). A high variability in P fixing capacity of the soils (r1/Ro = 0.02-0.76) was observed with the same level of available P. This fixation index is defined as the proportion of the added radioactivity ( 32 P) remaining in the soil solution after 1 min of exchange and a low fixing capacity is indicated by the values close to 1. The proportion of the total soil P that can possibly enter the soil solution and therefore is potentially available for plant uptake was measured using the traditional method (Bray I) and the isotopic method (E value). The high variability was also apparent in available P extracted by Bray I showing a range of 10 to 88% of the total P removed by the extracting solution. The incubation studies showed that the effectiveness of the P source for available P in the soil solution was related to their reactivity and the soil P fixing properties. The increase in the fixing capacity of the soils used caused a significant reduction in the E value, independent of the source of P used. A high positive and significant correlation between Bray I extracted P and the E value (r = 0.95) obtained from the different treatments, showed the relationship of the extractant for some forms of available P in soils where rock phosphate was applied. In
International Nuclear Information System (INIS)
D'Amato, R.J.; Largent, B.L.; Snowman, A.M.; Snyder, S.H.
1987-01-01
Citalopram is a potent and selective inhibitor of neuronal serotonin uptake. In rat brain membranes [ 3 H]citalopram demonstrates saturable and reversible binding with a KD of 0.8 nM and a maximal number of binding sites (Bmax) of 570 fmol/mg of protein. The drug specificity for [ 3 H]citalopram binding and synaptosomal serotonin uptake are closely correlated. Inhibition of [ 3 H]citalopram binding by both serotonin and imipramine is consistent with a competitive interaction in both equilibrium and kinetic analyses. The autoradiographic pattern of [ 3 H]citalopram binding sites closely resembles the distribution of serotonin. By contrast, detailed equilibrium-saturation analysis of [ 3 H]imipramine binding reveals two binding components, i.e., high affinity (KD = 9 nM, Bmax = 420 fmol/mg of protein) and low affinity (KD = 553 nM, Bmax = 8560 fmol/mg of protein) sites. Specific [ 3 H]imipramine binding, defined as the binding inhibited by 100 microM desipramine, is displaced only partially by serotonin. Various studies reveal that the serotonin-sensitive portion of binding corresponds to the high affinity sites of [ 3 H]imipramine binding whereas the serotonin-insensitive binding corresponds to the low affinity sites. Lesioning of serotonin neurons with p-chloroamphetamine causes a large decrease in [ 3 H]citalopram and serotonin-sensitive [ 3 H]imipramine binding with only a small effect on serotonin-insensitive [ 3 H]imipramine binding. The dissociation rate of [ 3 H]imipramine or [ 3 H]citalopram is not altered by citalopram, imipramine or serotonin up to concentrations of 10 microM. The regional distribution of serotonin sensitive [ 3 H]imipramine high affinity binding sites closely resembles that of [ 3 H]citalopram binding
International Nuclear Information System (INIS)
Javitch, J.A.
1985-01-01
Dopamine and norepinephrine are inactivated by specific high affinity transport systems which mediate the recapture of the amines into presynaptic nerve terminals. [ 3 H]Maxindol labels neuronal dopamine uptake sites in corpus striatum membranes and neuronal norepinephrine uptake sites in cerebral cortex and submaxillary/sublingual gland membranes. The potencies of various inhibitors of biogenic amine uptake in reducing [ 3 H]mazindol binding in striatal membranes correlate with their potencies for inhibition of neurona [ 3 H]dopamine accumulation, whereas their potencies in reducing [ 3 H]mazindol binding to cortical and salivary gland membranes correlate with their potencies for inhibition of neuronal [ 3 H]norepinephrine accumulation. The association of [ 3 H]mazindol binding sites with neuronal dopamine uptake sites in the corpus striatum is further supported by the reduction of [ 3 H]mazindol binding sites in striatal membranes following destruction of dopaminergic neurons by 6-hydroxydopamine. Similarly, destruction of noradrenergic neurons by N-(2-chloro-ethyl)-N-ethyl-2-bromobenzylamine(DSP-4) decreases [ 3 H]mazindol binding to cortical membranes. Dopamine and norepinephrine uptake sites in rat brain have been differentially visualized using [ 3 H]mazindol autoradiography. N-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces neuropathologic and clinical abnormalities in humans and animals that closely resemble idiopathic Parkinson disease. [ 3 H]MPTP binds with high affinity to brain membranes. The chemical specificity of the binding sites corresponds to structure-activity requirements for neurotoxicity
Retinal uptake and release of (/sup 3/H)DABA
Energy Technology Data Exchange (ETDEWEB)
Bauer, B; Ehinger, B [Lund Univ. (Sweden)
1978-03-01
The uptake of (/sup 3/H)DABA was studied in rat, guinea-pig and cat retinas in vivo and in rabbit retinas both in vivo and in vitro by autoradiography. (/sup 3/H)DABA was preferentially accumulated by a type of amacrine cell but after brief incubation or shortly after intravitreal injections there was not only a neuronal uptake but also a glial one. In guinea-pigs the glial labelling in vivo was significant also after 4 hr. The glial uptake (rabbits) was found to be saturable and temperature dependent as expected for an active uptake mechanism. The Ksub(m) of DABA uptake was 2.11 x 10/sup -5/ m and Vsub(max) 2.38 x 10/sup -5/ mol/mg/min. GABA competitively inhibited the DABA uptake. The uptake was not statistically significantly influenced by OMEGA-amino acids such as glycine, ..beta..-alanine, ..cap alpha..-alanine or epsilon-aminocaproic acid. The effect of different stimuli on the spontaneous efflux of radioactivity from (/sup 3/H)DABA preloaded rabbit retinas was studied with (/sup 3/H)DABA localized to neurons. Light flashes evoked a small but not statistically significant increased release whereas 40mM-K/sup +/ evoked an immediate and large increase. Unlabelled DABA, GABA and ..beta..-alanine (10/sup -5/M) increased the spontaneous efflux of (/sup 3/H)DABA but not glycine. It is concluded that there is in the retina of rats, guinea-pigs, cats, and rabbits, a glial high affinity uptake mechanism in addition to the neuronal uptake. DABA seems to be transported by the same mechanism as GABA in both systems. The DABA seems to be better retained in neurons than in glia in rats, cats and rabbits, which allows it to be used as a neuronal marker.
Drivers of Phosphorus Uptake by Barley Following Secondary Resource Application
Brod, Eva; Øgaard, Anne K. Falk; Krogstad, Tore; Haraldsen, Trond; Frossard, Emmanuel; Oberson, Astrid
2016-01-01
Minable rock phosphate is a finite resource. Replacing mineral phosphorus (P) fertilizer with P-rich secondary resources is one way to manage P more efficiently, but the importance of physicochemical and microbial soil processes induced by secondary resources for plant P uptake is still poorly understood. Using radioactive-labeling techniques, the fertilization effects of dairy manure, fish sludge, meat bone meal, and wood ash were studied as P uptake by barley after 44 days and compared with...
Drivers of phosphorus uptake by barley following secondary resource application
Eva eBrod; Eva eBrod; Anne Falk Øgaard; Tore eKrogstad; Trond Knapp Haraldsen; Emmanuel eFrossard; Astrid eOberson
2016-01-01
Minable rock phosphate is a finite resource. Replacing mineral phosphorus (P) fertilizer with P-rich secondary resources is one way to manage P more efficiently, but the importance of physicochemical and microbial soil processes induced by secondary resources for plant P uptake are still poorly understood. Using radioactive labelling techniques, the fertilization effects of dairy manure, fish sludge, meat bone meal and wood ash were studied as P uptake by barley after 44 days and compared wit...
Drivers of Phosphorus Uptake by Barley Following Secondary Resource Application
Brod, Eva; Øgaard, Anne K. Falk; Krogstad, Tore; Haraldsen, Trond; Frossard, Emmanuel; Oberson, Astrid
2016-01-01
Minable rock phosphate is a finite resource. Replacing mineral phosphorus (P) fertilizer with P-rich secondary resources is one way to manage P more efficiently, but the importance of physicochemical and microbial soil processes induced by secondary resources for plant P uptake is still poorly understood. Using radioactive-labeling techniques, the fertilization effects of dairy manure, fish sludge, meat bone meal, and wood ash were studied as P uptake by barley after 44 days and compared with...
Exertional oxygen uptake kinetics: a stamen of stamina?
Whipp, Brian J; Rossiter, H B; Ward, S A
2002-04-01
The fundamental pulmonary O(2) uptake (.VO(2)) response to moderate, constant-load exercise can be characterized as (d.VO(2)/dt)(tau)+Delta.VO(2) (t)=Delta.VO(2SS) where Delta.VO(2SS) is the steady-state response, and tau is the time constant, with the .VO(2) kinetics reflecting intramuscular O(2) uptake (.QO(2)) kinetics, to within 10%. The role of phosphocreatine (PCr) turnover in .QO(2) control can be explored using (31)P-MR spectroscopy, simultaneously with .VO(2). Although tau.VO(2) and tauPCr vary widely among subjects (approx. 20-65 s), they are not significantly different from each other, either at the on- or off-transient. A caveat to interpreting the "well-fit" exponential is that numerous units of similar Delta.VO(2SS) but with a wide tau distribution can also yield a .VO(2) response with an apparent single tau. This tau is, significantly, inversely correlated with lactate threshold and .VO(2max)(but is poorly predictive; a frail stamen, therefore), consistent with tau not characterizing a compartment with uniform kinetics. At higher intensities, the fundamental kinetics become supplemented with a slowly-developing phase, setting .VO(2)on a trajectory towards maximum .VO(2). This slow component is also demonstrable in Delta[PCr]: the decreased efficiency thereby reflecting a predominantly high phosphate-cost of force production rather than a high O(2)-cost of phosphate production. We also propose that the O(2)-deficit for the slow-component is more likely to reflect shifting Delta.VO(2SS) rather than a single one with a single tau.
Specific in vitro uptake of serotonin by cells in the anterior pituitary of the rat
International Nuclear Information System (INIS)
Johns, M.A.; Azmitia, E.C.; Krieger, D.T.
1982-01-01
In vivo studies have suggested that serotonin (5HT) influences anterior pituitary function at the hypothalamic level. The present in vitro study investigated the possibility that 5HT may act directly on the anterior pituitary. The high affinity uptake of [3H]5HT into adult rat anterior pituitary tissue was examined in two types of experiments. 1) To test the specificity and saturability of uptake of 5HT in the anterior pituitary, pituitary tissue was incubated (37 C) with [3H]5HT (10(-8)-10(-6) M) in the presence and absence of excess (10(-5) M) unlabeled 5HT, norepinephrine, fluoxetine (FLUOX), metergoline, or cyproheptadine. A Hofstee analysis of the specific uptake of [3H]5HT gave an apparent Km value of 4.23 x 10(-7) M and a Vmax of 1576 pmol/g/10 min [3H]5HT. The total uptake of [3H]5HT was not altered by norepinephrine or metergoline, but was significantly reduced (P less than 0.01-0.001) by FLUOX and cyproheptadine. Uptake was shown to be temperature and sodium dependent and not directly dependent on energy derived from glycolysis or aerobic metabolism. 2) To study the site of uptake of 5 HT in the anterior pituitary, in concomitant radioautographic experiments, tissue was incubated with [3H]5HT with and without excess 5HT or FLUOX. Three patterns of silver grain distribution were observed: 1) nonrandom concentrations over select anterior pituitary cells near blood vessels, 2) heavy aggregates of silver grains usually associated with blood vessels, and 3) a seemingly random dispersal of grains over pituitary tissue. Tissue incubated with [3H]5HT alone contained 10% heavily labeled cells, 32% moderately labeled cells, and 58% weakly labeled cells. In contrast, no heavily labeled cells were seen when tissue was incubated with either excess 5HT or FLUOX in addition to [3H]5HT. Our findings of saturable and specific high affinity uptake of [3H]5HT into a subgroup of anterior pituitary cells suggest a direct pituitary action of 5HT
2018-01-01
Background Visceral hypersensitivity is a common feature of irritable bowel syndrome. Cholinergic system involves in the development of visceral hypersensitivity, and high-affinity choline transporter (CHT1) is of crucial importance in choline uptake system. However, involvement of CHT1 in visceral hypersensitivity remains unknown. The research aimed to study the CHT1 expression in dorsal root ganglions (DRGs) and the role of CHT1 in visceral hypersensitivity. Methods Repetitive water avoidance stress (WAS) was used to induce visceral hypersensitivity in rats. Colorectal distension (CRD) was determined, and the abdominal withdrawal reflex (AWR) and threshold intensity data were recorded to measure the visceral sensitivity. After intraperitoneal injection of hemicholinium-3 (HC-3), the specific inhibitor of CHT1, CRD data were also recorded. The CHT1 expression of DRGs was investigated by Western blotting, immunohistochemistry, and quantitative RT-PCR. Acetylcholine levels in the DRGs were detected by the assay kit. Results Repetitive WAS increased the AWR score of CRD at high distension pressure and decreased the mean threshold of rats. The CHT1 expression and acetylcholine concentration of DRG were significantly increased in WAS rats. After the administration of HC-3, the AWR score in WAS group was significantly increased at higher distension pressure while the threshold intensity was significantly reduced compared to the normal saline group. Acetylcholine concentration was significantly lower than the normal saline rats. Conclusion Our research firstly reports that CHT1 is overexpressed in noninflammatory visceral hypersensitivity, and blockage of CHT1 can enhance the visceral hypersensitivity. CHT1 may play an inhibitory role in visceral hypersensitivity. PMID:29849603
Directory of Open Access Journals (Sweden)
Tal Noy-Porat
2016-03-01
Full Text Available Ricin, derived from the castor bean plant Ricinus communis, is one of the most potent and lethal toxins known, against which there is no available antidote. To date, the use of neutralizing antibodies is the most promising post-exposure treatment for ricin intoxication. The aim of this study was to isolate high affinity anti-ricin antibodies that possess potent toxin-neutralization capabilities. Two non-human primates were immunized with either a ricin-holotoxin- or subunit-based vaccine, to ensure the elicitation of diverse high affinity antibodies. By using a comprehensive set of primers, immune scFv phage-displayed libraries were constructed and panned. A panel of 10 antibodies (five directed against the A subunit of ricin and five against the B subunit was isolated and reformatted into a full-length chimeric IgG. All of these antibodies were found to neutralize ricin in vitro, and several conferred full protection to ricin-intoxicated mice when given six hours after exposure. Six antibodies were found to possess exceptionally high affinity toward the toxin, with KD values below pM (koff < 1 × 10−7 s−1 that were well correlated with their ability to neutralize ricin. These antibodies, alone or in combination, could be used for the development of a highly-effective therapeutic preparation for post-exposure treatment of ricin intoxication.
Foliar water uptake of Tamarix ramosissima from an atmosphere of high humidity.
Li, Shuang; Xiao, Hong-lang; Zhao, Liang; Zhou, Mao-Xian; Wang, Fang
2014-01-01
Many species have been found to be capable of foliar water uptake, but little research has focused on this in desert plants. Tamarix ramosissima was investigated to determine whether its leaves can directly absorb water from high humidity atmosphere and, if they can, to understand the magnitude and importance of foliar water uptake. Various techniques were adopted to demonstrate foliar water uptake under submergence or high atmospheric humidity. The mean increase in leaf water content after submergence was 29.38% and 20.93% for mature and tender leaves, respectively. In the chamber experiment, obvious reverse sap flow occurred when relative humidity (RH) was persistently above 90%. Reverse flow was recorded first in twigs, then in branches and stems. For the stem, the percentage of negative sap flow rate accounting for the maximum value of sap flow reached 10.71%, and its amount accounted for 7.54% of diurnal sap flow. Small rainfall can not only compensate water loss of plant by foliar uptake, but also suppress transpiration. Foliar uptake can appear in the daytime under certain rainfall events. High atmospheric humidity is beneficial for enhancing the water status of plants. Foliar uptake should be an important strategy of water acquisition for desert plants.
Foliar Water Uptake of Tamarix ramosissima from an Atmosphere of High Humidity
Directory of Open Access Journals (Sweden)
Shuang Li
2014-01-01
Full Text Available Many species have been found to be capable of foliar water uptake, but little research has focused on this in desert plants. Tamarix ramosissima was investigated to determine whether its leaves can directly absorb water from high humidity atmosphere and, if they can, to understand the magnitude and importance of foliar water uptake. Various techniques were adopted to demonstrate foliar water uptake under submergence or high atmospheric humidity. The mean increase in leaf water content after submergence was 29.38% and 20.93% for mature and tender leaves, respectively. In the chamber experiment, obvious reverse sap flow occurred when relative humidity (RH was persistently above 90%. Reverse flow was recorded first in twigs, then in branches and stems. For the stem, the percentage of negative sap flow rate accounting for the maximum value of sap flow reached 10.71%, and its amount accounted for 7.54% of diurnal sap flow. Small rainfall can not only compensate water loss of plant by foliar uptake, but also suppress transpiration. Foliar uptake can appear in the daytime under certain rainfall events. High atmospheric humidity is beneficial for enhancing the water status of plants. Foliar uptake should be an important strategy of water acquisition for desert plants.
Pegos, Vanessa R.; Santos, Rodrigo M. L.; Medrano, Francisco J.
2017-01-01
In Escherichia coli, the ATP-Binding Cassette transporter for phosphate is encoded by the pstSCAB operon. PstS is the periplasmic component responsible for affinity and specificity of the system and has also been related to a regulatory role and chemotaxis during depletion of phosphate. Xanthomonas citri has two phosphate-binding proteins: PstS and PhoX, which are differentially expressed under phosphate limitation. In this work, we focused on PhoX characterization and comparison with PstS. The PhoX three-dimensional structure was solved in a closed conformation with a phosphate engulfed in the binding site pocket between two domains. Comparison between PhoX and PstS revealed that they originated from gene duplication, but despite their similarities they show significant differences in the region that interacts with the permeases. PMID:28542513
International Nuclear Information System (INIS)
Kamal, L.A.; Le Quan-Bui, K.H.; Meyer, P.
1984-01-01
The uptake and content of serotonin in blood platelets were studied in patients with essential hypertension and in five families in which at least one member was hypertensive. Blood was obtained from male and female normotensive volunteers and hypertensive patients who were free of medication. Lineweaver-Burk plots of 3H-serotonin uptake from both control subjects and hypertensive patients were linear, which suggested simple Michaelis-Menten uptake kinetics. The maximal uptake velocity (Vmax) in hypertensive patients was significantly lower than in control subjects (control . 41.7 +/- 3.3 pmol/min/10(8) platelets, n . 17; hypertensive . 26.6 +/- 3.0 pmol/min/10(8) platelets, n . 16; p less than 0.005). The affinity constant (Km) was slightly but significantly lower in hypertensive patients (control . 0.70 +/- 0.08 microM; hypertensive . 0.46 +/- 0.08 microM; p less than 0.05). The serotonin content in blood platelets determined by high pressure liquid chromatography with electrochemical detection was significantly lower in hypertensive patients (control . 165.0 +/- 12.9 nmol/10(11) platelets, n . 29; hypertensive . 105.9 +/- 10.4 nmol/10(11) platelets, n . 27; p less than 0.001). In the five families investigated, the lowered serotonin content was observed in some normotensive members. The reduced number of carriers of serotonin uptake and the slight decrease in the affinity constant observed in platelets of patients with essential hypertension suggest that serotonin metabolism is altered in essential hypertension and that blood platelets may be a useful model in studying the serotonergic modifications at the molecular level
International Nuclear Information System (INIS)
Muenze, R.; Shyre, R.; Seifert, S.; Guethert, I.; Kretschmar, M.; Kampf, G.; Knop, G.; Mohnike, W.; Schmidt, J.
1986-01-01
The biodistribution of various 14 C labeled organocations (ammonium, phosphonium) and cationic technetium complexes (TcCl 2 DMPE 2 ,TcDMPE 3 + ) was studied in rats to find potential relations between the chemical composition, structure, molecular size, lipophilicity and heart uptake. All of the radioactive cations were distributed in a similar manner, but with different biokinetics. Molecules containing several electronegative atoms in their ligand structure, e.g. nitrogen or oxygen which enhance polarity, were rapidly accumulated, but washed out again with resultant transient and diminished heart uptake. More highly lipophilic materials, by contrast, showed more extensive accumulation and persistent retention in the heart. The effect of human serum albumin on heart uptake was studied in a perfused heart model. Strong albumin binding prevented extensive heart uptake. This undesirable effect was neutralized by adding detergents to the perfusion bath. Evidence from these animal experiments was considered in the development of a new heart-seeking technetium compound (Tc-DPO), which is characterized by rapid accumulation in the human heart and substantially delayed washout. Heart images with minimal overlap of the inferoposterior wall and the right liver lobe were available in no more than 10 minutes p.i. in both planar and SPECT modes. A deficit in the inferior region was much more clearly defined than on the corresponding Thallium image. (Author)
High-Strength / High Alkaline Resistant Fe-Phosphate Glass Fibers as Concrete Reinforcement
Energy Technology Data Exchange (ETDEWEB)
Mariano Velez
2008-03-31
Calcium-iron-phosphate glasses were developed whose chemical durabilities in alkaline solutions (pH 13) were comparable or superior to those of commercial alkaline-resistant (AR) silica-based glasses. However, the tensile strength of Ca-Fe-phosphate fibers, after being exposed to alkaline environments, including wet Portland cement pastes, is lower than that of current AR silicate fibers. Another series of Ca-Fe-phosphate glasses were developed with excellent chemical durability in strong acidic solutions (H2SO4, HF), indicating potential applications where silica-based fibers degrade very quickly, including E-glass. The new Ca-Fe-phosphate glasses can be melted and processed 300 to 500°C lower than silica-based glasses. This offers the possibility of manufacturing glass fibers with lower energy costs by 40-60% and the potential to reduce manufacturing waste and lower gas emissions. It was found that Ca-Fe-phosphate melts can be continuously pulled into fibers depending on the slope of the viscosity-temperature curve and with viscosity ~100 poise, using multi-hole Pt/Rh bushings.
A high affinity monoclonal antibody recognizing the light chain of human coagulating factor VII.
Sarial, Sheila; Asadi, Farzad; Jeddi-Tehrani, Mahmood; Hadavi, Reza; Bayat, Ali Ahmad; Mahmoudian, Jafar; Taghizadeh-Jahed, Masoud; Shokri, Fazel; Rabbani, Hodjattallah
2012-12-01
Factor VII (FVII) is a serine protease-coagulating element responsible for the initiation of an extrinsic pathway of clot formation. Here we generated and characterized a high affinity monoclonal antibody that specifically recognizes human FVII. Recombinant human FVII (rh-FVII) was used for the production of a monoclonal antibody using BALB/c mice. The specificity of the antibody was determined by Western blot using plasma samples from human, mouse, sheep, goat, bovine, rabbit, and rat. Furthermore, the antibody was used to detect transiently expressed rh-FVII in BHK21 cell line using Western blot and sandwich ELISA. A mouse IgG1 (kappa chain) monoclonal antibody clone 1F1-B11 was produced against rh-FVII. The affinity constant (K(aff)) of the antibody was calculated to be 6.4×10(10) M(-1). The antibody could specifically recognize an epitope on the light chain of hFVII, with no reactivity with factor VII from several other animals. In addition, transiently expressed rh-FVII in BHK21 cells was recognized by 1F1-B11. The high affinity as well as the specificity of 1F1-B11 for hFVII will facilitate the affinity purification of hFVII and also production of FVII deficient plasma and minimizes the risk of bovine FVII contamination when fetal bovine serum-supplemented media are used for production and subsequent purification of rh-FVII.
Affine and quasi-affine frames for rational dilations
DEFF Research Database (Denmark)
Bownik, Marcin; Lemvig, Jakob
2011-01-01
In this paper we extend the investigation of quasi-affine systems, which were originally introduced by Ron and Shen [J. Funct. Anal. 148 (1997), 408-447] for integer, expansive dilations, to the class of rational, expansive dilations. We show that an affine system is a frame if, and only if......, the corresponding family of quasi-affine systems are frames with uniform frame bounds. We also prove a similar equivalence result between pairs of dual affine frames and dual quasi-affine frames. Finally, we uncover some fundamental differences between the integer and rational settings by exhibiting an example...
Highly Doped Phosphate Glass Fibers for Compact Lasers and Amplifiers: A Review
Directory of Open Access Journals (Sweden)
Nadia Giovanna Boetti
2017-12-01
Full Text Available In recent years, the exploitation of compact laser sources and amplifiers in fiber form has found extensive applications in industrial and scientific fields. The fiber format offers compactness, high beam quality through single-mode regime and excellent heat dissipation, thus leading to high laser reliability and long-term stability. The realization of devices based on this technology requires an active medium with high optical gain over a short length to increase efficiency while mitigating nonlinear optical effects. Multicomponent phosphate glasses meet these requirements thanks to the high solubility of rare-earth ions in their glass matrix, alongside with high emission cross-sections, chemical stability and high optical damage threshold. In this paper, we review recent advances in the field thanks to the combination of highly-doped phosphate glasses and innovative fiber drawing techniques. We also present the main performance achievements and outlook both in continuous wave (CW and pulsed mode regimes.
Uptake and metabolism of carbohydrates by Bradyrhizobium japonicum bacteroids
International Nuclear Information System (INIS)
Salminen, S.O.; Streeter, J.G.
1987-01-01
Bradyrhizobium japonicum bacteroids were isolated anaerobically and were supplied with 14 C-labeled trehalose, sucrose, UDP-glucose, glucose, or fructose under low O 2 (2% in the gas phase). Uptake and conversion of 14 C to CO 2 were measured at intervals up to 90 minutes. Of the five compounds studied, UDP-glucose was most rapidly absorbed but it was very slowly metabolized. Trehalose was the sugar most rapidly converted to CO 2 , and fructose was respired at a rate of at least double that of glucose. Sucrose and glucose were converted to CO 2 at a very low but measurable rate ( 2 at a rate 30 times greater than the conversion of carbon Number 6 to CO 2 , indicating high activity of the pentose phosphate pathway. Enzymes of the Entner-Doudoroff pathway were not detected in bacteroids, but very low activities of sucrose synthase and phosphofructokinase were demonstrated. Although metabolism of sugars by B. japonicum bacteroids was clearly demonstrated, the rate of sugar uptake was only 1/30 to 1/50 the rate of succinate uptake. The overall results support the view that, although bacteroids metabolize sugars, the rates are very low and are inadequate to support nitrogenase
DEFF Research Database (Denmark)
Sawers, Ruairidh J. H.; Svane, Simon; Quan, Clement
2017-01-01
-internal and -external fungal structures, mycorrhizal phosphorus uptake, and accumulation of transcripts encoding plant PHT1 family phosphate transporters varied among lines. Superior response in Oh43 is correlated with extensive development of root-external hyphae, accumulation of specific Pht1 transcripts and high...
International Nuclear Information System (INIS)
Klinck, J.S.; Green, W.W.; Mirza, R.S.; Nadella, S.R.; Chowdhury, M.J.; Wood, C.M.; Pyle, G.G.
2007-01-01
Branchial binding kinetics and gastro-intestinal uptake of copper and cadmium where examined in yellow perch (Perca flavescens) from a metal-contaminated lake (Hannah Lake, Sudbury, Ontario, Canada) and an uncontaminated lake (James Lake, North Bay, Ontario, Canada). An in vivo approach was taken for gill binding comparisons while an in vitro gut binding assay was employed for gastro-intestinal tract (GIT) uptake analysis. By investigating metal uptake at the gill and the gut we cover the two main routes of metal entry into fish. Comparisons of water and sediment chemistries, metal burdens in benthic invertebrate, and metal burdens in the livers of perch from the two study lakes clearly show that yellow perch from Hannah L. are chronically exposed to a highly metal-contaminated environment compared to a reference lake. We found that metal-contaminated yellow perch showed no significant difference in gill Cd binding compared to reference fish, but they did show significant decreases in new Cd binding and absorption in their GITs. The results show that gill Cd binding may involve low-capacity, high-affinity binding sites, while gastro-intestinal Cd uptake involves binding sites that are high-capacity, low-affinity. From this we infer that Cd may be more critically controlled at the gut rather than gills. Significant differences in branchial Cu binding (increased binding) were observed in metal-contaminated yellow perch. We suggest that chronic waterborne exposure to Cu (and/or other metals) may be the dominant influence in gill Cu binding rather than chronic exposure to high Cu diets. We give supporting evidence that Cd is taken up in the GIT, at least in part, by a similar pathway as Ca 2+ , principally that elevated dietary Ca 2+ reduces Cd binding and uptake. Overall our study reveals that metal pre-exposure via water and diet can alter uptake kinetics of Cu and Cd at the gill and/or the gut
Energy Technology Data Exchange (ETDEWEB)
Klinck, J.S. [Department of Biology, McMaster University, Hamilton, Ont. L8S 4K1 (Canada)], E-mail: klinckjs@mcmaster.ca; Green, W.W.; Mirza, R.S. [Department of Biology, McMaster University, Hamilton, Ont. L8S 4K1 (Canada); Department of Biology, Nipissing University, North Bay, Ont. P1B 8L7 (Canada); Nadella, S.R.; Chowdhury, M.J.; Wood, C.M. [Department of Biology, McMaster University, Hamilton, Ont. L8S 4K1 (Canada); Pyle, G.G. [Department of Biology, Nipissing University, North Bay, Ont. P1B 8L7 (Canada)
2007-08-30
Branchial binding kinetics and gastro-intestinal uptake of copper and cadmium where examined in yellow perch (Perca flavescens) from a metal-contaminated lake (Hannah Lake, Sudbury, Ontario, Canada) and an uncontaminated lake (James Lake, North Bay, Ontario, Canada). An in vivo approach was taken for gill binding comparisons while an in vitro gut binding assay was employed for gastro-intestinal tract (GIT) uptake analysis. By investigating metal uptake at the gill and the gut we cover the two main routes of metal entry into fish. Comparisons of water and sediment chemistries, metal burdens in benthic invertebrate, and metal burdens in the livers of perch from the two study lakes clearly show that yellow perch from Hannah L. are chronically exposed to a highly metal-contaminated environment compared to a reference lake. We found that metal-contaminated yellow perch showed no significant difference in gill Cd binding compared to reference fish, but they did show significant decreases in new Cd binding and absorption in their GITs. The results show that gill Cd binding may involve low-capacity, high-affinity binding sites, while gastro-intestinal Cd uptake involves binding sites that are high-capacity, low-affinity. From this we infer that Cd may be more critically controlled at the gut rather than gills. Significant differences in branchial Cu binding (increased binding) were observed in metal-contaminated yellow perch. We suggest that chronic waterborne exposure to Cu (and/or other metals) may be the dominant influence in gill Cu binding rather than chronic exposure to high Cu diets. We give supporting evidence that Cd is taken up in the GIT, at least in part, by a similar pathway as Ca{sup 2+}, principally that elevated dietary Ca{sup 2+} reduces Cd binding and uptake. Overall our study reveals that metal pre-exposure via water and diet can alter uptake kinetics of Cu and Cd at the gill and/or the gut.
Bambuterol: uptake and metabolism in guinea pig isolated lungs
International Nuclear Information System (INIS)
Ryrfeldt, A.; Nilsson, E.; Tunek, A.; Svensson, L.A.
1988-01-01
The lung uptake and biotransformation of 3 H-bambuterol, a prodrug to terbutaline, were studied using isolated perfused and ventilated guinea pig lungs. 14 C-Sucrose was used as an extracellular marker. The lung uptake of bambuterol was significantly (0.05 greater than or equal to P greater than or equal to 0.001) higher than that found for sucrose in single-pass perfusion experiments. High-performance liquid chromatographic (HPLC) analysis showed that 95.6 +/- 3.6% of the effluent 3 H radioactivity was attributable to bambuterol. In recirculating experiments (120 min) the lung biotransformation of 3 H-bambuterol (8.5 pmol/ml) was studied. Both oxidative and hydrolytic metabolism took place. The dominating metabolites were hydroxylated bambuterol and the monocarbamate derivative which is a product of hydrolysis of bambuterol. Traces of terbutaline were also formed. The results show that bambuterol has a certain affinity to lung tissue and that the drug is, to some extent, biotransformed in the guinea pig lung
Honey, Denise M.; Best, Annie; Qiu, Huawei
2018-01-01
ABSTRACT Metelimumab (CAT192) is a human IgG4 monoclonal antibody developed as a TGFβ1-specific antagonist. It was tested in clinical trials for the treatment of scleroderma but later terminated due to lack of efficacy. Subsequent characterization of CAT192 indicated that its TGFβ1 binding affinity was reduced by ∼50-fold upon conversion from the parental single-chain variable fragment (scFv) to IgG4. We hypothesized this result was due to decreased conformational flexibility of the IgG that could be altered via engineering. Therefore, we designed insertion mutants in the elbow region and screened for binding and potency. Our results indicated that increasing the elbow region linker length in each chain successfully restored the isoform-specific and high affinity binding of CAT192 to TGFβ1. The crystal structure of the high binding affinity mutant displays large conformational rearrangements of the variable domains compared to the wild-type antigen-binding fragment (Fab) and the low binding affinity mutants. Insertion of two glycines in both the heavy and light chain elbow regions provided sufficient flexibility for the variable domains to extend further apart than the wild-type Fab, and allow the CDR3s to make additional interactions not seen in the wild-type Fab structure. These interactions coupled with the dramatic conformational changes provide a possible explanation of how the scFv and elbow-engineered Fabs bind TGFβ1 with high affinity. This study demonstrates the benefits of re-examining both structure and function when converting scFv to IgG molecules, and highlights the potential of structure-based engineering to produce fully functional antibodies. PMID:29333938
International Nuclear Information System (INIS)
Penefsky, H.S.
1985-01-01
Incubation of [gamma- 32 P]ATP with a molar excess of the membrane-bound form of mitochondrial ATPase (F1) results in binding of the bulk of the radioactive nucleotide in high affinity catalytic sites (Ka = 10(12) M-1). Subsequent initiation of respiration by addition of succinate or NADH is accompanied by a profound decrease in the affinity for ATP. About one-third of the bound radioactive ATP appears to dissociate, that is, the [gamma- 32 P]ATP becomes accessible to hexokinase. The NADH-stimulated dissociation of [gamma- 32 P]ATP is energy-dependent since the stimulation is inhibited by uncouplers of oxidative phosphorylation and is prevented by respiratory chain inhibitors. The rate of the energy-dependent dissociation of ATP that occurs in the presence of NADH, ADP, and Pi is commensurate with the measured initial rate of ATP synthesis in NADH-supported oxidative phosphorylation catalyzed by the same submitochondrial particles. Thus, the rate of dissociation of ATP from the high affinity catalytic site of submitochondrial particles meets the criterion of kinetic competency under the conditions of oxidative phosphorylation. These experiments provide evidence in support of the argument that energy conserved during the oxidation of substrates by the respiratory chain can be utilized to reduce the very tight binding of product ATP in high affinity catalytic sites and to promote dissociation of the nucleotide
Enhancement of the agronomic effectiveness of phosphate rock in a ferralsol from Cuba
International Nuclear Information System (INIS)
Rodriguez, R.; Herrera, J.A.; Garcia, A.; Nuviola, A.
2002-01-01
The Ferralsols from Ciego de Avila, Cuba, have a pH near neutrality and very low exchangeable acidity, thus, they are not suitable for direct application of phosphate rock. In laboratory and greenhouse experiments, different P fertilizers were tested in order to assess their agronomic effectiveness through the use of nuclear and conventional methods. The phosphate rocks (PRs) came from different deposits (Higuanojo, La Pimienta and Trinidad de Guedes from Cuba; Riecito, Baja California and North Carolina from other countries). Partial acidulation (PA) of some of these rocks was also evaluated. Trinidad de Guedes PAPRs were found to be highly effective compared to their natural PR when evaluated through dry matter production, P uptake and isotopic parameters. Further field experiments are needed to validate the greenhouse results to enhance the agronomic effectiveness of the local Trinidad de Guedes PR through partial acidulation. (author)
Uptake of CrO{sub 4}{sup 2-} ions by Fe-treated tri-calcium phosphate
Energy Technology Data Exchange (ETDEWEB)
Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E., E-mail: juan.serrano@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)
2010-07-01
CrO{sub 4}{sup 2-} ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10{sup -4} M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO{sub 4}{sup 2-} ions was 7.10 x 10{sup -3} mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters {Delta}H{sup 0}, {Delta}G{sup 0} and {Delta}S{sup 0} were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)
Vogensen, Stine B.; Marek, Aleš; Bay, Tina; Wellendorph, Petrine; Kehler, Jan; Bundgaard, Christoffer; Frølund, Bente; Pedersen, Martin H.F.; Clausen, Rasmus P.
2013-01-01
3-Hydroxycyclopent-1-enecarboxylic acid (HOCPCA, 1) is a potent ligand for the high-affinity GHB binding sites in the CNS. An improved synthesis of 1 together with a very efficient synthesis of [3H]-1 is described. The radiosynthesis employs in situ generated lithium trimethoxyborotritide. Screening of 1 against different CNS targets establishes a high selectivity and we demonstrate in vivo brain penetration. In vitro characterization of [3H]-1 binding shows high specificity to the high-affinity GHB binding sites. PMID:24053696
Kinetic parameters of silicon uptake by rice cultivars
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Priscila Oliveira Martins
2012-02-01
Full Text Available Silicon is considered an important chemical element for rice, because it can improve tolerance to biotic and abiotic stress. However, in many situations no positive effect of silicon was observed, probably due to genetic factors. The objective of this research was to monitor Si uptake kinetics and identify responses of rice cultivars in terms of Si uptake capacity and use. The experiment was carried out in a greenhouse of the São Paulo State University (UNESP, Brazil. The experiment was arranged in a completely randomized, factorial design with three replications. that consisted of two rice cultivars and two Si levels. Kinetic parameters (Vmax, Km, and Cmin, root morphology variables, dry matter yield, Si accumulation and levels in shoots and roots, uptake efficiency, utilization efficiency, and root/shoot ratio were evaluated. Higher Si concentrations in the nutrient solution did not increase rice dry matter. The development of the low-affinity silicon uptake system of the rice cultivar 'Caiapó' was better than of 'Maravilha'.
Greiner, Ralf
2017-11-08
Kinetic parameters for the dephosphorylation of sodium phytate and a series of partially phosphorylated myo-inositol phosphates were determined at pH 3.0 and pH 5.0 for three phytase preparations (Aspergillus niger, Escherichia coli, rye). The enzymes showed lower affinity and turnover numbers at pH 3 compared to pH 5 toward all myo-inositol phosphates included in the study. The number and distribution of phosphate groups on the myo-inositol ring affected the kinetic parameters. Representatives of the individual phytate dephosphorylation pathways were identified as the best substrates of the phytases. Within the individual phytate dephosphorylation pathways, the pentakisphosphates were better substrates compared to the tetrakisphosphates or phytate itself. E. coli and rye phytase showed comparable activities at both pH values toward the tetrakis- and trisphosphate, whereas A. niger phytase exhibited a higher activity toward the tetrakisphosphate. A myo-inositol phosphate with alternate phosphate groups was shown to be not significantly dephosphorylated by the phytases.
Pore-Water Carbonate and Phosphate As Predictors of Arsenate Toxicity in Soil.
Lamb, Dane T; Kader, Mohammed; Wang, Liang; Choppala, Girish; Rahman, Mohammad Mahmudur; Megharaj, Mallavarapu; Naidu, Ravi
2016-12-06
Phytotoxicity of inorganic contaminants is influenced by the presence of competing ions at the site of uptake. In this study, interaction of soil pore-water constituents with arsenate toxicity was investigated in cucumber (Cucumis sativa L) using 10 contrasting soils. Arsenate phytotoxicity was shown to be related to soluble carbonate and phosphate. The data indicated that dissolved phosphate and carbonate had an antagonistic impact on arsenate toxicity to cucumber. To predict arsenate phytotoxicity in soils with a diverse range of soil solution properties, both carbonate and phosphate were required. The relationship between arsenic and pore-water toxicity parameters was established initially using multiple regression. In addition, based on the relationship with carbonate and phosphate we successively applied a terrestrial biotic ligand-like model (BLM) including carbonate and phosphate. Estimated effective concentrations from the BLM-like parametrization were strongly correlated to measured arsenate values in pore-water (R 2 = 0.76, P soils.
International Nuclear Information System (INIS)
Abou Seer, A.M.M.
2002-01-01
the present study aimed to evaluate to evaluate the of phosphate solubilizing bacteria (PSB) and vesicular arbuscular mycorrhizae(VAM) as microbiological mean to convert the sparingly soluble P into available from utilized by plant through excretion of acid and alkaline phosphatase. rock phosphate as natural and a cheap source of P- fertilizer was applied in the present study. To trace the effect of microbial activity and phosphatase enzymes on phosphate availability from its compounds , set of experiments were conducted either in the lab. or green house. The obtained results could be summarized as following:- 1- phosphate solubilizing bacteria(PSB) w isolated from samples of fertile soil, 16 colonies showed positive reaction were chosen .2- bacteria , which exhibited high phosphate clearing zone (PCZ) selected to detect their efficiencies for dissolving rock phospate and select the effective one (most potent) on the basis of highest production of phosphatase and phosphorus solubilization.3- identification of the most potent (pseudomonas aeruginosa) 4- effective environmental and nutritional factors on phosphatase production by pseudomonas aeruginosa were discussed.green-house experiment: inoculation of wheat (triticum aestivum cv.sakha 8) with either PSB and /or VAM with or without rock-P fertilization was under taken. dual inoculation with psb (pseudomonas aeruginosa) and VAM improved the dry matter yield and N and P uptake by wheat as compared to other treatments. application of psb as well as VAM increased the availability of rock phosphate to be utilized by wheat
Preparation of Edible Corn Starch Phosphate with Highly Reactive ...
African Journals Online (AJOL)
1Food & Bioengineering Department, Henan University of Science and Technology, Luoyang, Henan 471003 ... Purpose: To prepare edible corn starch phosphate under optimized experimental conditions. ... In food industry, starch phosphate.
International Nuclear Information System (INIS)
Kondo, Y.
1998-01-01
The effect of phosphate ion on the filtration characteristics of solids generated in a high level liquid waste was experimentally examined. Addition of phosphate ion into the simulated HLLW induced the formation of phosphate such as zirconium phosphate and phosphomolybdic acid. The filtration rate of zirconium phosphate abruptly dropped in the midst of filtration because of a gel-cake formation on the filter surface. The denitration of the simulated HLLW contained zirconium phosphate improved the filterability of this gelatinous solid. The filtration rates of denitrated HLLW decreased with increase of the phosphate ion concentration, since the solids formed by denitration had irregular particle size and configuration in the simulated HLLW with phosphate ion. To increase the filtration rate of denitrated HLLW, a solid suspension filtration tester was designed. The solid-suspension accelerated the filtration rate only in the simulated HLLW with more than 1500 ppm phosphate ion concentration. Under this condition, the simple agitation can easily suspend the constituent solids of filter cake in the solution and a much higher filtration rate can be obtained because the filter cake is continuously swept from the filter surface by rotation of propellers. (authors)
Whitehurst, Charles E; Annis, D Allen
2008-07-01
Advances in combinatorial chemistry and genomics have inspired the development of novel affinity selection-based screening techniques that rely on mass spectrometry to identify compounds that preferentially bind to a protein target. Of the many affinity selection-mass spectrometry techniques so far documented, only a few solution-based implementations that separate target-ligand complexes away from unbound ligands persist today as routine high throughput screening platforms. Because affinity selection-mass spectrometry techniques do not rely on radioactive or fluorescent reporters or enzyme activities, they can complement traditional biochemical and cell-based screening assays and enable scientists to screen targets that may not be easily amenable to other methods. In addition, by employing mass spectrometry for ligand detection, these techniques enable high throughput screening of massive library collections of pooled compound mixtures, vastly increasing the chemical space that a target can encounter during screening. Of all drug targets, G protein coupled receptors yield the highest percentage of therapeutically effective drugs. In this manuscript, we present the emerging application of affinity selection-mass spectrometry to the high throughput screening of G protein coupled receptors. We also review how affinity selection-mass spectrometry can be used as an analytical tool to guide receptor purification, and further used after screening to characterize target-ligand binding interactions, enabling the classification of orthosteric and allosteric binders.
L-Myo-inositol 1-phosphate synthase in the aquatic fern Azolla filiculoides.
Benaroya, Rony Oren; Zamski, Eli; Tel-Or, Elisha
2004-02-01
L-Myo-inositol 1-phosphate synthase (INPS EC 5.5.1.4) catalyzes the conversion of D-glucose 6-phosphate to L-myo-inositol 1-phosphate. INPS is a key enzyme involved in the biosynthesis of phytate which is a common form of stored phosphates in higher plants. The present study monitored the increase of INPS expression in Azolla filiculoides resulting from exposure to inorganic phosphates, metals and salt stress. The expression of INPS was significantly higher in Azolla plants that were grown in rich mineral growth medium than those maintained on nutritional growth medium. The expression of INPS protein and corresponding mRNA increased in plants cultured in minimal nutritional growth medium when phosphate or Zn2+, Cd2+ and NaCl were added to the growth medium. When employing rich mineral growth medium, INPS protein content increased with the addition of Zn2+, but decreased in the presence of Cd2+ and NaCl. These results indicated that accumulation of phytate in Azolla is a result of the intensified expression of INPS protein and mRNA, and its regulation may be primarily derived by the uptake of inorganic phosphate, and Zn2+, Cd2+ or NaCl.
Mandal, Asit; Purakayastha, T J; Patra, A K; Sanyal, S K
2012-07-01
A greenhouse experiment evaluated the effect of phytoextraction of arsenic from a contaminated soil by Chinese Brake Fern (Pteris vittata L.) and its subsequent effects on growth and uptake of arsenic by rice (Oryza sativa L.) crop. Pteris vittata was grown for one or two growing cycles of four months each with two phosphate sources, using single super phosphate (SSP) and di-ammonium phosphate (DAP). Rice was grown on phytoextracted soils followed by measurements of biomass yield (grain, straw, and root), arsenic concentration and, uptake by individual plant parts. The biomass yield (grain, straw and rice) of rice was highest in soil phytoextracted with Pteris vittata grown for two cycles and fertilized with diammonium phosphate (DAP). Total arsenic uptake in contaminated soil ranged from 8.2 to 16.9 mg pot(-1) in first growing cycle and 5.5 to 12.0 mg pot(-1) in second growing cycle of Pteris vittata. There was thus a mean reduction of 52% in arsenic content of rice grain after two growing cycle of Pteris vittata and 29% after the one growing cycle. The phytoextraction of arsenic contaminated soil by Pteris vittata was beneficial for growing rice resulted in decreased arsenic content in rice grain of <1 ppm. There was a mean improvement in rice grain yield 14% after two growing cycle and 8% after the one growing cycle of brake fern.
Sorption behavior of Zn(II) ions on synthetic apatitic calcium phosphates
Sebei, Haroun; Pham Minh, Doan; Nzihou, Ange; Sharrock, Patrick
2015-12-01
The synthesis, characterization and the reactivity of apatitic calcium phosphates (Ca-HA, chemical formula Ca10(PO4)6(OH)2) is reported. Calcium carbonate (CaCO3) and potassium dihydrogen orthophosphate (KH2PO4) were selected as economical starting materials for the synthesis of Ca-HA under atmospheric conditions. Monocalcium phosphate monohydrate (MCPM), dicalcium phosphate dihydrate (DCPD), and octacalcium phosphate pentahydrate (OCP) were identified as the main intermediates of the synthesis reaction. The product obtained after 48 h of reaction contains mainly low-crystalline Ca-HA and small amounts of other calcium phosphates such as octacalcium phosphate (OCP), B-type carbonate apatite (CAP), as well as unreacted calcium carbonate. This Ca-HA was found to be active for the removal of Zn2+ from an aqueous solution. Its sorption capacity reached up to 120 mg of Zn2+ per g of Ca-HA powder after 24 h of reaction. The monitoring of soluble Zn, Ca and P during the sorption experiment allowed characterizing the mechanism of Zn uptake. Dissolution-precipitation, ionic exchange and surface complexation are the three main mechanisms involved in the sorption processes. The contribution of these mechanisms is discussed in detail.
International Nuclear Information System (INIS)
Anggi Nico Flatian; Iswandi Anas; Atang Sutandi; Ishak
2016-01-01
The "3"2P isotope technique has been used to trace P nutrients in the soil and soil-plant systems. The use of the isotope "3"2P has made it possible to differentiate the P contribution derived from phosphate solubilizing microorganism activity and the fertilizer P in the soil. The aims of the study were to obtain the quantitative data of P contribution derived from phosphate-solubilizing microorganism activity (Aspergillus niger and Burkholderia cepacia), rock phosphate and SP-36 through P uptake by the plants using isotope "3"2P technique and also to study the effects on growth and production of corn plants. The results were showed that phosphate-solubilizing microorganism, rock phosphate and SP-36 was produced specific activity ("3"2P) lower than control. The results were indicated that all treatments could contribute P for the plants. The lower specific activity was caused by supply P from rock phosphate and SP-36, and also was caused by solubilized of unavailable "3"1P from PSM activity, which decreased specific activity on labeled soil. The combination of phosphate-solubilizing microorganism and SP-36 treatments produced the highest P contribution, significantly higher than control and SP-36 only. Phosphate derived from combination of microorganism and SP-36 treatments ranging from 56.06% - 68.54% after 50 days planting, after 35 days planting, 51.96% - 59.65% on stover, 46.33% - 47.70% on grain and 53.02% - 59.87% on corn cob. In addition, the treatments could significantly support the plant growth and yield. It is expressed by increased number of leave at 35 days after planting, dry weight of leave at 35 days after planting and dry weight of grain. (author)
Uptake of radionuclides by vegetation at a High Arctic location
International Nuclear Information System (INIS)
Dowdall, M.; Gwynn, J.P.; Moran, C.; O'Dea, J.; Davids, C.; Lind, B.
2005-01-01
Radionuclide levels in vegetation from a High Arctic location were studied and compared to in situ soil concentrations. Levels of the anthropogenic radionuclide 137 Cs and the natural radionuclides 40 K, 238 U, 226 Ra and 232 Th are discussed and transfer factor (TF) values and aggregated transfer (Tag) values are calculated for vascular plants. Levels of 137 Cs in vegetation generally followed the order mosses > lichen > vascular plants. The uptake of 137 Cs in vascular plants showed an inverse relationship with the uptake of 40 K, with 137 Cs TF and Tag values generally higher than 40 K TF and Tag values. 40 K activity concentrations in all vegetation showed little correlation to associated soil concentrations, while the uptake of 238 U, 226 Ra and 232 Th by vascular and non-vascular plants was generally low. - Uptake of the anthropogenic radionuclide 137 Cs is highest for moss species
International Nuclear Information System (INIS)
Krizsan, D.; Varga, E.; Benyhe, S.; Szucs, M.; Borsodi, A.; Hosztafi, S.
1991-01-01
C-6 derivatives-hydrazones, phenylhydrazones, dinitrophenylhydrazones, oximes and semicarbazones - of morphinane-6-ones were synthesized and their binding characteristics were studied on rat brain membranes. The dihydromorphinone and oxymorphone derivatives compete for the ( 3 H)naloxone binding sites with high affinity, while the dihydrocodeinone and oxycodone derivatives are less potent. The affinity of the new compounds is decreased for the delta sites as compared to the parent ligands. The ligands bearing bulky substituents also bind with low affinity to the kappa sites. The modification decreased the Na + -index of compounds indicating their mixed agonist-antagonist character. The dihydromorphinone derivatives are all capable to block irreversibly the high affinity binding site of ( 3 H)naloxone, whereas the dihydrocodeinone derivatives block irreversibly the low affinity site. A possible mechanism for the inhibition is suggested
Directory of Open Access Journals (Sweden)
Chen Zhao
2018-01-01
Full Text Available Background. Visceral hypersensitivity is a common feature of irritable bowel syndrome. Cholinergic system involves in the development of visceral hypersensitivity, and high-affinity choline transporter (CHT1 is of crucial importance in choline uptake system. However, involvement of CHT1 in visceral hypersensitivity remains unknown. The research aimed to study the CHT1 expression in dorsal root ganglions (DRGs and the role of CHT1 in visceral hypersensitivity. Methods. Repetitive water avoidance stress (WAS was used to induce visceral hypersensitivity in rats. Colorectal distension (CRD was determined, and the abdominal withdrawal reflex (AWR and threshold intensity data were recorded to measure the visceral sensitivity. After intraperitoneal injection of hemicholinium-3 (HC-3, the specific inhibitor of CHT1, CRD data were also recorded. The CHT1 expression of DRGs was investigated by Western blotting, immunohistochemistry, and quantitative RT-PCR. Acetylcholine levels in the DRGs were detected by the assay kit. Results. Repetitive WAS increased the AWR score of CRD at high distension pressure and decreased the mean threshold of rats. The CHT1 expression and acetylcholine concentration of DRG were significantly increased in WAS rats. After the administration of HC-3, the AWR score in WAS group was significantly increased at higher distension pressure while the threshold intensity was significantly reduced compared to the normal saline group. Acetylcholine concentration was significantly lower than the normal saline rats. Conclusion. Our research firstly reports that CHT1 is overexpressed in noninflammatory visceral hypersensitivity, and blockage of CHT1 can enhance the visceral hypersensitivity. CHT1 may play an inhibitory role in visceral hypersensitivity.
Qudsia, Sehar; Merugu, Siva B; Mangukiya, Hitesh B; Hema, Negi; Wu, Zhenghua; Li, Dawei
2018-04-30
Antibody display libraries have become a popular technique to screen monoclonal antibodies for therapeutic purposes. An important aspect of display technology is to generate an optimization library by changing antibody affinity to antigen through mutagenesis and screening the high affinity antibody. In this study, we report a novel lentivirus display based optimization library antibody in which Agtuzumab scFv is displayed on cell membrane of HEK-293T cells. To generate an optimization library, hotspot mutagenesis was performed to achieve diverse antibody library. Based on sequence analysis of randomly selected clones, library size was estimated approximately to be 1.6 × 10 6 . Lentivirus display vector was used to display scFv antibody on cell surface and flow cytometery was performed to check the antibody affinity to antigen. Membrane bound scFv antibodies were then converted to secreted antibody through cre/loxP recombination. One of the mutant clones, M8 showed higher affinity to antigen in flow cytometery analysis. Further characterization of cellular and secreted scFv through western blot showed that antibody affinity was increased by three fold after mutagenesis. This study shows successful construction of a novel antibody library and suggests that hotspot mutagenesis could prove a useful and rapid optimization tool to generate similar libraries with various degree of antigen affinity. Copyright © 2018 Elsevier Inc. All rights reserved.
Flexible Molybdenum Electrodes towards Designing Affinity Based Protein Biosensors.
Kamakoti, Vikramshankar; Panneer Selvam, Anjan; Radha Shanmugam, Nandhinee; Muthukumar, Sriram; Prasad, Shalini
2016-07-18
Molybdenum electrode based flexible biosensor on porous polyamide substrates has been fabricated and tested for its functionality as a protein affinity based biosensor. The biosensor performance was evaluated using a key cardiac biomarker; cardiac Troponin-I (cTnI). Molybdenum is a transition metal and demonstrates electrochemical behavior upon interaction with an electrolyte. We have leveraged this property of molybdenum for designing an affinity based biosensor using electrochemical impedance spectroscopy. We have evaluated the feasibility of detection of cTnI in phosphate-buffered saline (PBS) and human serum (HS) by measuring impedance changes over a frequency window from 100 mHz to 1 MHz. Increasing changes to the measured impedance was correlated to the increased dose of cTnI molecules binding to the cTnI antibody functionalized molybdenum surface. We achieved cTnI detection limit of 10 pg/mL in PBS and 1 ng/mL in HS medium. The use of flexible substrates for designing the biosensor demonstrates promise for integration with a large-scale batch manufacturing process.
Hemoglobin affinity in Andean rodents
Directory of Open Access Journals (Sweden)
HRVOJ OSTOJIC
2002-01-01
Full Text Available Blood hemoglobin oxygen affinity (P50 was measured in three Andean species and in the laboratory rat (control, all raised near sea level. Chinchilla lanigera (Molina, 1792 has an altitudinal habitat range from low Andean slopes up to 3000 m., while Chinchilla brevicaudata (Waterhouse, 1848 has an altitudinal range from 3000 to 5000 m. The laboratory type guinea pig, wild type guinea pig (Cavia porcellus, (Waterhouse, 1748, and laboratory rat (Rattus norvegicus were also raised at sea level. The Andean species had high hemoglobin oxygen affinities (low P50 compared with the rat. Chinchilla brevicaudata had a higher affinity than Chinchilla lanigera. The wild type guinea pig had a higher affinity than the laboratory type. As has been shown in other species, this is another example of an inverse correlation between the altitude level and the P50 values. This is the first hemoglobin oxygen affinity study in Chinchilla brevicaudata.
Niyogi, Som; Brix, Kevin V; Grosell, Martin
2014-05-01
The freshwater pulmonate snail, Lymnaea stagnalis, is the most sensitive aquatic organism tested to date for Ni. We undertook a series of experiments to investigate the underlying mechanism(s) for this observed hypersensitivity. Consistent with previous experiments, juvenile snail growth in a 21-day exposure was reduced by 48% relative to the control when exposed to 1.3 μg l(-1) Ni (EC20 less than the lowest concentration tested). Ca(2+) homeostasis was significantly disrupted by Ni exposure as demonstrated by reductions in net Ca(2+) uptake, and reductions in Ca(2+) concentrations in the hemolymph and soft tissues. We also observed reduced soft tissue [Mg(2+)]. Snails underwent a significant alkalosis with hemolymph pH increasing from 8.1 to 8.3 and hemolymph TCO2 increasing from 19 to 22 mM in control versus Ni-exposed snails, respectively. Unlike in previous studies with Co and Pb, snail feeding rates were found to be unaffected by Ni at the end of the exposure. Snails accumulated Ni in the soft tissue in a concentration-dependent manner, and Ni uptake experiments with (63)Ni revealed a biphasic uptake profile - a saturable high affinity component at low exposure concentrations (36-189 nM) and a linear component at the high exposure concentrations (189-1,897 nM). The high affinity transport system had an apparent Km of 89 nM Ni(2+) and Vmax of 2.4 nmol g(-1)h(-1). This equates to a logK of 7.1, significantly higher than logK's (2.6-5.2) for any other aquatic organisms evaluated to date, which will have implications for Biotic Ligand Model development. Finally, pharmacological inhibitors that block Ca(2+) uptake pathways in snails did not inhibit Ni uptake, suggesting that the uptake of Ni does not occur via Ca(2+) uptake pathways. As with Cu and Pb, the exact mechanism for the significant disruption in Ca(2+) homeostasis and reduction in juvenile snail growth remains unknown. Copyright © 2014 Elsevier B.V. All rights reserved.
Rydberg, Hanna A.; Matson, Maria; Å mand, Helene L.; Esbjö rner, Elin K.; Nordé n, Bengt
2012-01-01
Cell-penetrating peptides (CPPs) are able to traverse cellular membranes and deliver macromolecular cargo. Uptake occurs through both endocytotic and nonendocytotic pathways, but the molecular requirements for efficient internalization are not fully understood. Here we investigate how the presence of tryptophans and their position within an oligoarginine influence uptake mechanism and efficiency. Flow cytometry and confocal fluorescence imaging are used to estimate uptake efficiency, intracellular distribution and toxicity in Chinese hamster ovarian cells. Further, membrane leakage and lipid membrane affinity are investigated. The peptides contain eight arginine residues and one to four tryptophans, the tryptophans positioned either at the N-terminus, in the middle, or evenly distributed along the amino acid sequence. Our data show that the intracellular distribution varies among peptides with different tryptophan content and backbone spacing. Uptake efficiency is higher for the peptides with four tryptophans in the middle, or evenly distributed along the peptide sequence, than for the peptide with four tryptophans at the N-terminus. All peptides display low cytotoxicity except for the one with four tryptophans at the N-terminus, which was moderately toxic. This finding is consistent with their inability to induce efficient leakage of dye from lipid vesicles. All peptides have comparable affinities for lipid vesicles, showing that lipid binding is not a decisive parameter for uptake. Our results indicate that tryptophan content and backbone spacing can affect both the CPP uptake efficiency and the CPP uptake mechanism. The low cytotoxicity of these peptides and the possibilities of tuning their uptake mechanism are interesting from a therapeutic point of view. © 2012 American Chemical Society.
Rydberg, Hanna A.
2012-07-10
Cell-penetrating peptides (CPPs) are able to traverse cellular membranes and deliver macromolecular cargo. Uptake occurs through both endocytotic and nonendocytotic pathways, but the molecular requirements for efficient internalization are not fully understood. Here we investigate how the presence of tryptophans and their position within an oligoarginine influence uptake mechanism and efficiency. Flow cytometry and confocal fluorescence imaging are used to estimate uptake efficiency, intracellular distribution and toxicity in Chinese hamster ovarian cells. Further, membrane leakage and lipid membrane affinity are investigated. The peptides contain eight arginine residues and one to four tryptophans, the tryptophans positioned either at the N-terminus, in the middle, or evenly distributed along the amino acid sequence. Our data show that the intracellular distribution varies among peptides with different tryptophan content and backbone spacing. Uptake efficiency is higher for the peptides with four tryptophans in the middle, or evenly distributed along the peptide sequence, than for the peptide with four tryptophans at the N-terminus. All peptides display low cytotoxicity except for the one with four tryptophans at the N-terminus, which was moderately toxic. This finding is consistent with their inability to induce efficient leakage of dye from lipid vesicles. All peptides have comparable affinities for lipid vesicles, showing that lipid binding is not a decisive parameter for uptake. Our results indicate that tryptophan content and backbone spacing can affect both the CPP uptake efficiency and the CPP uptake mechanism. The low cytotoxicity of these peptides and the possibilities of tuning their uptake mechanism are interesting from a therapeutic point of view. © 2012 American Chemical Society.
High-affinity receptors for bombesin-like peptides in normal guinea pig lung membranes
International Nuclear Information System (INIS)
Lach, E.; Trifilieff, A.; Landry, Y.; Gies, J.P.
1991-01-01
The binding of the radiolabeled bombesin analogue [ 125 I-Tyr 4 ]bombesin to guinea-pig lung membranes was investigated. Binding of [ 125 I-Tyr 4 ]bombesin was specific, saturable, reversible and linearly related to the protein concentration. Scatchard analysis of equilibrium binding data at 25C indicated the presence of a single class of non-interacting binding sites for bombesin (B max = 7.7 fmol/mg protein). The value of the equilibrium dissociation constant (K D = 90 pM) agrees with a high-affinity binding site. Bombesin and structurally related peptides such as [ 125 I-Tyr 4 ]bombesin, neuromedin B and neuromedin C inhibited the binding of [ 125 I-Tyr 4 ]bombesin in an order of potencies as follows: [ 125 I-Tyr 4 ]bombesin > bombesin ≥ neuromedin C much-gt neuromedin B. These results indicate that guinea-pig lung membranes possess a single class of bombesin receptors with a high affinity for bombesin and a lower one for neuromedin B
International Nuclear Information System (INIS)
Hanyu, Naohiro; Nishio, Kosuke; Hatakeyama, Mamoru; Yasuno, Hiroshi; Tanaka, Toshiyuki; Tada, Masaru; Nakagawa, Takashi; Sandhu, Adarsh; Abe, Masanori; Handa, Hiroshi
2009-01-01
For affinity purification of drug target protein we have developed magnetic carriers, narrow in size distribution (184±9 nm), which exhibit minimal non-specific binding of unwanted proteins. The carriers were highly dispersed in aqueous solutions and highly resistant to organic solvents, which enabled immobilization of various hydrophobic chemicals as probes on the carrier surfaces. Utilizing the carriers we have automated the process of separation and purification of the target proteins that had been done by manual operation previously.
Crystalline cerium(IV) phosphates
International Nuclear Information System (INIS)
Herman, R.G.; Clearfield, A.
1976-01-01
The ion exchange behaviour of seven crystalline cerium(IV) phosphates towards some of the alkali metal cations is described. Only two of the compounds (A and C) possess ion exchange properties in acidic solutions. Four others show some ion exchange characteristics in basic media with some of the alkali cations. Compound G does not behave as an ion exchanger in solutions of pH + , but show very little Na + uptake. Compound E undergoes ion exchange with Na + and Cs + , but not with Li+. Both Li + and Na + are sorbed by compounds A and C. The results are indicative of structures which show steric exclusion phenomena. (author)
HEPPELL, J.
2014-06-24
© 2014 John Wiley & Sons Ltd. The readily available global rock phosphate (P) reserves may run out within the next 50-130 years, causing soils to have a reduced P concentration which will affect plant P uptake. Using a combination of mathematical modelling and experimental data, we investigated potential plant-based options for optimizing crop P uptake in reduced soil P environments. By varying the P concentration within a well-mixed agricultural soil, for high and low P (35.5-12.5mgL-1 respectively using Olsen\\'s P index), we investigated branching distributions within a wheat root system that maximize P uptake. Changing the root branching distribution from linear (evenly spaced branches) to strongly exponential (a greater number of branches at the top of the soil) improves P uptake by 142% for low-P soils when root mass is kept constant between simulations. This causes the roots to emerge earlier and mimics topsoil foraging. Manipulating root branching patterns, to maximize P uptake, is not enough on its own to overcome the drop in soil P from high to low P. Further mechanisms have to be considered to fully understand the impact of P reduction on plant development.
DEFF Research Database (Denmark)
Sø, Helle Ugilt
different calcite-equilibrated solutions that varied in pH, PCO2, ionic strength and activity of Ca2+, CO3 2- and HCO3 -. To avoid the precipitation of phosphate or arsenic-containing minerals the experiments were conducted using a short reaction time (generally 3 h) and a low concentration of phosphate...... adsorption affinity for calcite is greater as compared to arsenate and the phosphate sorption isotherms are more strongly curved. However, the amount of both arsenate and phosphate adsorbed varied with the solution composition in the same manner. In particular, adsorption increased as the CO3 2- activity...... decreased (at constant pH) and as pH increased (at constant CO3 2- activity). The dependency on the carbonate activity indicates competition for sorption sites between carbonate and arsenate/phosphate, whereas the pH dependency is likely a response to changes in arsenate and phosphate speciation...
Formation of calcium phosphates by vapour diffusion in highly concentrated ionic micro-droplets
Energy Technology Data Exchange (ETDEWEB)
Iafisco, M. [Alma Mater Studiorum Universita di Bologna, Dipartimento di Chimica ' ' G. Ciamician' ' , Via Selmi 2, 40126 Bologna (Italy); Universita del Piemonte Orientale, Dipartimento di Scienze Mediche, Via Solaroli 4, 28100 Novara (Italy); Delgado-Lopez, J.M.; Gomez-Morales, J.; Hernandez-Hernandez, M.A.; Rodriguez-Ruiz, I. [Laboratorio de Estudios Cristalograficos, IACT CSIC-UGR, Edificio Lopez Neyra, Avenida del Conocimiento, s/n 18100 Armilla (Spain); Roveri, N. [Alma Mater Studiorum Universita di Bologna, Dipartimento di Chimica ' ' G. Ciamician' ' , Via Selmi 2, 40126 Bologna (Italy)
2011-08-15
In this work we have used the sitting drop vapour diffusion technique, employing the ''crystallization mushroom '' to analyze the evolution of calcium phosphate crystallization in micro-droplets containing high initial concentrations of Ca{sup 2+} and HPO{sub 4}{sup 2-}. The decomposition of NH{sub 4}HCO{sub 3} solution produces vapours of NH{sub 3} and CO{sub 2} which diffuse through the droplets containing an aqueous solution of Ca(CH{sub 3}COO){sub 2} and (NH{sub 4}){sub 2}HPO{sub 4}. The result is the increase of pH by means of the diffusion of NH{sub 3} gas and the doping of the calcium phosphate with CO{sub 3}{sup 2-} ions by means of the diffusion of CO{sub 2} gas. The pH of the crystallization process is monitored and the precipitates at different times are characterized by XRD, FTIR, TGA, SEM and TEM techniques. The slow increase of pH and the high concentration of Ca{sup 2+} and HPO{sub 4}{sup 2-} in the droplets induce the crystallization of three calcium phosphate phases: dicalcium phosphate dihydrate (DCPD, brushite), octacalcium phosphate (OCP) and carbonate-hydroxyapatite (HA). The amount of HA nanocrystals with needle-like morphology and dimensions of about 100 nm, closely resembling the inorganic phase of bones, gradually increases, with the precipitation time up to 7 days, whereas the amount of DCPD, growing along the b axis, increases up to 3 days. Then, DCDP crystals start to hydrolyze yielding OCP nanoribbons and HA nanocrystals. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Evaluation of phosphatic fertilizers on weltland paddy using 32P as tracer
International Nuclear Information System (INIS)
Basu, S.N.; Chowdhury, B.; Mukhopadhyay, P.; Dhua, S.P.
1974-01-01
Superphosphate, nitrophosphate and dicalcium phosphate tagged with 32 P were tested on wetland paddy at two levels each in pot culture experiment. All the three fertilizers performed equally in respect of dry matter yield, total phosphorus uptake and fertilizer phosphorus uptake. A higher percent utilization of fertilizer phosphorus was noticed at lower level of fertilizer. Densitometric study of the plant autoradiographs showed maximum accumulation of fertilizer phosphorus in the culm, followed by in leaf sheath and accumulation in leaf blades being the least. (author)
A mix-and-read drop-based in vitro two-hybrid method for screening high-affinity peptide binders
Cui, Naiwen; Zhang, Huidan; Schneider, Nils; Tao, Ye; Asahara, Haruichi; Sun, Zhiyi; Cai, Yamei; Koehler, Stephan A.; de Greef, Tom F. A.; Abbaspourrad, Alireza; Weitz, David A.; Chong, Shaorong
2016-01-01
Drop-based microfluidics have recently become a novel tool by providing a stable linkage between phenotype and genotype for high throughput screening. However, use of drop-based microfluidics for screening high-affinity peptide binders has not been demonstrated due to the lack of a sensitive functional assay that can detect single DNA molecules in drops. To address this sensitivity issue, we introduced in vitro two-hybrid system (IVT2H) into microfluidic drops and developed a streamlined mix-and-read drop-IVT2H method to screen a random DNA library. Drop-IVT2H was based on the correlation between the binding affinity of two interacting protein domains and transcriptional activation of a fluorescent reporter. A DNA library encoding potential peptide binders was encapsulated with IVT2H such that single DNA molecules were distributed in individual drops. We validated drop-IVT2H by screening a three-random-residue library derived from a high-affinity MDM2 inhibitor PMI. The current drop-IVT2H platform is ideally suited for affinity screening of small-to-medium-sized libraries (103–106). It can obtain hits within a single day while consuming minimal amounts of reagents. Drop-IVT2H simplifies and accelerates the drop-based microfluidics workflow for screening random DNA libraries, and represents a novel alternative method for protein engineering and in vitro directed protein evolution. PMID:26940078
Energy Technology Data Exchange (ETDEWEB)
Arahira, Takaaki; Maruta, Michito, E-mail: maruta@college.fdcnet.ac.jp; Matsuya, Shigeki
2017-05-01
Biphasic calcium phosphate consisting of hydroxyapatite (HA) and β-tricalcium phosphate(β-TCP) is an excellent bone substitute with controllable bioresorbability. Fabrication of biphasic calcium phosphate with self-setting ability is expected to enhance its potential application as bone substitute. In this study, mixtures of α-TCP and β-TCP with various compositions were prepared through α-β phase transition of α-TCP powder at 1000 °C for various periods. These powders were mixed with 0.25 M Na{sub 2}HPO{sub 4} at a P/L ratio of 2, and then hardened at 37 °C at 100% RH for up to 24 h. Material properties of biphasic HA/β-TCP cement with different α-TCP/β-TCP composition were characterized. These cements were also evaluated with respect to cell response in vitro using MC3T3-E1 cell lines. In conclusion, mechanical and biological properties of HA/β-TCP cement could be controlled by changing the heat treatment time of α-TCP powder at 1000 °C. In vitro results indicated that cell proliferation and ALP activity increased with increase β-TCP content. - Highlights: • We could fabricate biphasic HA/β-TCP cements using heat treated α-TCP powder. • It is easy to control the ratio of α-TCP to β-TCP changing the heat treatment time up to 48 h. • Both cell number and ALP activity increased with increase in β-TCP content. • In vitro results showed that β-TCP has superior cell affinity to HA.
Extremely High Phosphate Sorption Capacity in Cu-Pb-Zn Mine Tailings.
Huang, Longbin; Li, Xiaofang; Nguyen, Tuan A H
2015-01-01
Elevated inorganic phosphate (Pi) concentrations in pore water of amended tailings under direct revegetation may cause toxicity in some native woody species but not native forbs or herb species, all of which are key constituents in target native plant communities for phytostabilizing base metal mine tailings. As a result, Pi sorption capacity has been quantified by a conventional batch procedure in three types of base metal mine tailings sampled from two copper (Cu)-lead (Pb)-zinc (Zn) mines, as the basis for Pi-fertiliser addition. It was found that the Pi-sorption capacity in the tailings and local soil was extremely high, far higher than highly weathered agricultural soils in literature, but similar to those of volcanic ash soils. The Langmuir P-sorption maximum was up to 7.72, 4.12, 4.02 and 3.62 mg P g-1 tailings, in the fresh tailings of mixed Cu-Pb-Zn streams (MIMTD7), the weathered tailings of mixed Cu-Pb-Zn streams (MIMTD5), EHM-TD (fresh Cu-stream, high magnetite content) and local soil (weathered shale and schist), respectively. Physicochemical factors highly correlated with the high Pi-sorption in the tailings were fine particle distribution, oxalate and dithionite-citrate-bicarbonate extractable Fe (FeO and Fed), oxalate-extractable Al and Mn, and the levels of soluble Cd and Zn, and total S and Fe. Large amounts of amorphous Fe oxides and oxyhydroxides may have been formed from the oxidation of pyritic materials and redox cycles of Fe-minerals (such as pyrite (FeS2), ankerite (Ca(Fe Mg)(CO3)2 and siderite (FeCO3), as indicated by the extractable FeO values. The likely formation of sparingly soluble Zn-phosphate in the Pb-Zn tailings containing high levels of Zn (from sphalerite ((Zn,Fe)S, ZnS, (Zn,Cd)S)) may substantially lower soluble Zn levels in the tailings through high rates of Pi-fertiliser addition. As a result, the possibility of P-toxicity in native plant species caused by the addition of soluble phosphate fertilizers would be minimal.
Sun, Tingting; Li, Mingjun; Shao, Yun; Yu, Lingyan; Ma, Fengwang
2017-01-01
Elemental phosphorus (Pi) is essential to plant growth and development. The family of phosphate transporters (PHTs) mediates the uptake and translocation of Pi inside the plants. Members include five sub-cellular phosphate transporters that play different roles in Pi uptake and transport. We searched the Genome Database for Rosaceae and identified five clusters of phosphate transporters in apple ( Malus domestica ), including 37 putative genes. The MdPHT1 family contains 14 genes while MdPHT2 has two, MdPHT3 has seven, MdPHT4 has 11, and MdPHT5 has three. Our overview of this gene family focused on structure, chromosomal distribution and localization, phylogenies, and motifs. These genes displayed differential expression patterns in various tissues. For example, expression was high for MdPHT1;12, MdPHT3;6 , and MdPHT3;7 in the roots, and was also increased in response to low-phosphorus conditions. In contrast, MdPHT4;1, MdPHT4;4 , and MdPHT4;10 were expressed only in the leaves while transcript levels of MdPHT1;4, MdPHT1;12 , and MdPHT5;3 were highest in flowers. In general, these 37 genes were regulated significantly in either roots or leaves in response to the imposition of phosphorus and/or drought stress. The results suggest that members of the PHT family function in plant adaptations to adverse growing environments. Our study will lay a foundation for better understanding the PHT family evolution and exploring genes of interest for genetic improvement in apple.
International Nuclear Information System (INIS)
Kamel, N.H.M.
2008-01-01
The mean activity values of the radionuclide 226 Ra, 238 U and 232 Th decay series, and the radioactive isotopes of 40 K in Bq/kg dry weight of the phosphate ore (Pho-ore), single super phosphate granules, (SSP-G), single super phosphate powder (SSP-P), triple super phosphate (TSP), and phosphogypsum (CaSO 4 ) samples were determined. CaSO 4 sample was found to contain, 300 Bq/kg of radioactive 238 U which is less than the values found in other studied phosphate samples. CaSO 4 sample was found to contain the highest amount of 226 Ra concentration value of 850 Bq/kg. Phosphate fertilizer components are acidic character, therefore, the solid surfaces will in general acquire a surface electric charge when contact with polar solvent such as water. The net electric charge obtained through uptake or release of potential determining ions (e.g, H + or OH - ). Thus the solid surfaces tend to adsorb and/or release of different ions to maintain neutral. The aim of this study is to determine the electric charge and the surface electric potential at the phosphate fertilizer materials
Changes in calcium uptake rate by rat cardiac mitochondria during postnatal development.
Bassani, R A; Fagian, M M; Bassani, J W; Vercesi, A E
1998-10-01
Ca2+ uptake, transmembrane electrical potential (Deltapsim) and oxygen consumption were measured in isolated ventricular mitochondria of rats from 3 days to 5 months of age. Estimated values of ruthenium red-sensitive, succinate-supported maximal rate of Ca2+ uptake (Vmax, expressed as nmol Ca2+/min/mg protein) were higher in neonates and gradually fell during postnatal development (from 435+/-24 at 3-6 days, to 156+/-10 in adults,Palpha-ketoglutarate as substrates) and state 3ADP (alpha-ketoglutarate-supported) respiration rates, as well as Deltapsim values (approximately-150 mV). Respiration-independent Deltapsim and Ca2+ uptake, supported by valinomycin-induced K+ efflux were also investigated at these ages. A transient Deltapsim (approximately -30 mV) was evoked by valinomycin in both neonatal and adult mitochondria. Respiration-independent Ca2+ uptake was also transient, but its initial rate was significantly higher in neonates than in adults (49. 4+/-10.0v 28.0+/-5.7 mmol Ca2+/min/mg protein,P<0.01). These results indicate that Ca2+ uptake capacity of rat cardiac mitochondria is remarkably high just after birth and declines over the first weeks of postnatal life, without change in apparent affinity of the transporter. Increased mitochondrial Ca2+ uptake rate in neonates appears to be related to the uniporter itself, rather than to modification of the driving force of the transport. Copyright 1998 Academic Press
Intercellular Uptake of Technetium-99m Pertechnetate by Different Types of Cell Lines
International Nuclear Information System (INIS)
Safri Zainal Abidin; Raizulnasuha Abdul Rashid; Muhammad Afiq Khairil Anuar; Wan Nordiana A Abd Rahman
2015-01-01
The purpose of this study is to determine the technetium-99m pertechnetate ( 99m TcO 4 ) intercellular uptake by different types of cell lines. HeLa, human fetal osteoblast (hFOB), glial and glioma cell lines grown in 6-wells culture plates were incubated with 99m TcO 4 of activity of 200, 400, 600, 800 and 1000 μCi for 30 minutes at 37 degree Celsius and 5 % CO 2 humidified atmosphere. After incubation, the cells were washed 3 times with phosphate buffer saline to remove the extracellular traces of 99m TcO 4 . Measurement of the intercellular 99m TcO 4 into the cells was calculated. The intercellular uptake of 99m TcO 4 was found to be inversely correlate to the radioactivity. HHeLa cell shows the highest uptake followed by hFOB, glial and glioma cell lines. Comparison of uptake between normal and cancer cells present indistinguishable results. The findings of this study suggest that the intercellular uptake of 99m TcO 4 is highly dependent on the type of cells despite no significant different of uptake was found between normal and cancer cell lines. The level of radioactivity is also an important determinant factor that influence the uptake of 99m TcO 4 into the cell. The study will be the first precedent toward understanding the cellular characteristics and pharmacokinetic of non-invasive imaging tracer for future molecular imaging and therapy. (author)
Accurate determination of the oxidative phosphorylation affinity for ADP in isolated mitochondria.
Directory of Open Access Journals (Sweden)
Gilles Gouspillou
Full Text Available BACKGROUND: Mitochondrial dysfunctions appear strongly implicated in a wide range of pathologies. Therefore, there is a growing need in the determination of the normal and pathological integrated response of oxidative phosphorylation to cellular ATP demand. The present study intends to address this issue by providing a method to investigate mitochondrial oxidative phosphorylation affinity for ADP in isolated mitochondria. METHODOLOGY/PRINCIPAL FINDINGS: The proposed method is based on the simultaneous monitoring of substrate oxidation (determined polarographically and phosphorylation (determined using the glucose-hexokinase glucose-6-phosphate dehydrogenase-NADP(+ enzymatic system rates, coupled to the determination of actual ADP and ATP concentrations by bioluminescent assay. This enzymatic system allows the study of oxidative phosphorylation during true steady states in a wide range of ADP concentrations. We demonstrate how the application of this method allows an accurate determination of mitochondrial affinity for ADP from both oxidation (K(mVox and phosphorylation (K(mVp rates. We also demonstrate that determination of K(mVox leads to an important overestimation of the mitochondrial affinity for ADP, indicating that mitochondrial affinity for ADP should be determined using phosphorylation rate. Finally, we show how this method allows the direct and precise determination of the mitochondrial coupling efficiency. Data obtained from rat skeletal muscle and liver mitochondria illustrate the discriminating capabilities of this method. CONCLUSIONS/SIGNIFICANCE: Because the proposed method allows the accurate determination of mitochondrial oxidative phosphorylation affinity for ADP in isolated mitochondria, it also opens the route to a better understanding of functional consequences of mitochondrial adaptations/dysfunctions arising in various physiological/pathophysiological conditions.
Synthesis of site-heterologous haptens for high-affinity anti-pyraclostrobin antibody generation.
Mercader, Josep V; Agulló, Consuelo; Abad-Somovilla, Antonio; Abad-Fuentes, Antonio
2011-03-07
The design and synthesis of functional chemical derivatives of small organic molecules is usually a key step for the intricate production of a variety of bioconjugates. In this respect, the derivatization site at which the spacer arm is introduced in immunizing conjugates constitutes a highly critical parameter for the generation of high-affinity and selective antibodies. However, due to the usual complexity of the required synthetic procedures, the appropriate comparison of alternative tethering positions has often been neglected. In the present study, meticulous strategies were followed to prepare synthetic derivatives of pyraclostrobin with the same linkers located at diverse rationally-chosen sites. Activity appraisal of antibodies and bioconjugates was carried out by bidimensional competitive direct and indirect immunoassays, and a superior performance of two of the three synthesized haptens was found. Finally, a detailed analysis of the conformations of the target molecule and the synthesized haptens in aqueous solution was done using computer assisted molecular modeling techniques. This study suggested that the lower titers and affinities of one set of antibodies are most probably due to conformational effects of the spacer arm in the immunizing bioconjugate.
Yoshimi, T; Kawabata, S; Taira, S; Okuno, A; Mikawa, R; Murayama, S; Tanaka, K; Takikawa, O
2015-11-07
A novel screening system, using affinity imaging mass spectrometry (AIMS), has been developed to identify protein aggregates or organ structures in unfixed human tissue. Frozen tissue sections are positioned on small (millimetre-scale) stainless steel chips and incubated with an extensive library of small molecules. Candidate molecules showing specific affinity for the tissue section are identified by imaging mass spectrometry (IMS). As an example application, we screened over a thousand compounds against Alzheimer's disease (AD) brain tissue and identified several compounds with high affinity for AD brain sections containing tau deposits compared to age-matched controls. It should also be possible to use AIMS to isolate chemical compounds with affinity for tissue structures or components that have been extensively modified by events such as oxidation, phosphorylation, acetylation, aggregation, racemization or truncation, for example, due to aging. It may also be applicable to biomarker screening programs.
Active site of Zn2+-dependent sn-glycerol-1-phosphate dehydrogenase from Aeropyrum pernix K1
Directory of Open Access Journals (Sweden)
Jin-Suk Han
2005-01-01
Full Text Available The enzyme sn-glycerol-1-phosphate dehydrogenase (Gro1PDH, EC 1.1.1.261 is key to the formation of the enantiomeric configuration of the glycerophosphate backbone (sn-glycerol-1-phosphate of archaeal ether lipids. This enzyme catalyzes the reversible conversion between dihydroxyacetone phosphate and glycerol-1-phosphate. To date, no information about the active site and catalytic mechanism of this enzyme has been reported. Using the sequence and structural information for glycerol dehydrogenase, we constructed six mutants (D144N, D144A, D191N, H271A, H287A and D191N/H271A of Gro1PDH from Aeropyrum pernix K1 and examined their characteristics to clarify the active site of this enzyme. The enzyme was found to be a zinc-dependent metalloenzyme, containing one zinc ion for every monomer protein that was essential for activity. Site-directed mutagenesis of D144 increased the activity of the enzyme. Mutants D144N and D144A exhibited low affinity for the substrates and higher activity than the wild type, but their affinity for the zinc ion was the same as that of the wild type. Mutants D191N, H271A and H287A had a low affinity for the zinc ion and a low activity compared with the wild type. The double mutation, D191N/ H271A, had no enzyme activity and bound no zinc. From these results, it was clarified that residues D191, H271 and H287 participate in the catalytic activity of the enzyme by binding the zinc ion, and that D144 has an effect on substrate binding. The structure of the active site of Gro1PDH from A. pernix K1 seems to be similar to that of glycerol dehydrogenase, despite the differences in substrate specificity and biological role.
International Nuclear Information System (INIS)
Fukuda, E.K.
1983-01-01
Molecular electron affinities have historically been difficult quantities to measure accurately. These difficulties arise from differences in structure between the ion and neutral as well as the existence of excited negative ion states. To circumvent these problems, relative electron affinities were determined in this dissertation by studying equilibrium electron transfer reactions using a pulsed ion cyclotron resonance (ICR) spectrometer. Direct measurement of ion and neutral concentrations for reactions of the general type, A - + B = B - + A, allow calculation of the equilibrium constant and, therefore, the free energy change. The free energy difference is related to the difference in electron affinities between A and B. A relative electron affinity scale covering a range of about 45 kcal/mol was constructed with various substituted p-benzoquinones, nitrobenzenes, anhydrides, and benzophenones. To assign absolute electron affinities, various species with accurately known electron affinities are tied to the scale via ion-cyclotron double resonance bracketing techniques. After the relative scale is anchored to these species with well-known electron affinities, the scale is then used as a check on other electron affinity values as well as generating new electron affinity values. Many discrepancies were found between the electron affinities measured using the ICR technique and previous literature determinations
Zhang, Min; Zhao, Quanli; Xue, Peiying; Zhang, Shijie; Li, Bowen; Liu, Wenju
2017-10-01
Silicon (Si) may decrease the uptake and accumulation of arsenic (As) in rice. However, the effects of Si/As ratios in growth medium on arsenic uptake, arsenite efflux to the external medium and translocation of arsenite in rice are currently unclear. Rice seedlings (Oryza sativa L.) were exposed to nutrient solutions with 10 μM arsenite [As(III)] or 10 μM arsenate [As(V)] to explore the influence of different silicic acid concentrations (0, 10, 100, 1000 μM) on arsenic uptake and translocation of arsenite with or without 91 μM phosphate for 24 h. Arsenic speciation was determined in nutrient solutions, roots, and shoots. In the arsenite treatments, different Si/As ratios (1:1, 10:1, 100:1) did not affect As(III) uptake by rice roots, however they did inhibit translocation of As(III) from roots to shoots significantly (P rice roots and shoots. A Si/As ratio of 100:1 reduced As(III) translocation from roots to shoots markedly without phosphate. When phosphate was supplied, As(III) translocation from roots to shoots was significantly inhibited by Si/As ratios of 10:1 and 100:1. The results indicated that in the presence of P, different silicic acid concentrations did not impact arsenite uptake and transport in rice when arsenite was supplied. However, a Si/As ratio of 100:1 inhibited As(V) uptake, as well as As(III) efflux and translocation from roots to shoots when arsenate was supplied. Copyright © 2017 Elsevier Ltd. All rights reserved.
Adsorption of endotoxins on Ca2+ -iminodiacetic acid by metal ion affinity chromatography.
Lopes, André Moreni; Romeu, Jorge Sánchez; Meireles, Rolando Páez; Perera, Gabriel Marquez; Morales, Rolando Perdomo; Pessoa, Adalberto; Cárdenas, Lourdes Zumalacárregui
2012-11-01
Endotoxins (also known as lipopolysaccharides (LPS)) are undesirable by-products of recombinant proteins, purified from Escherichia coli. LPS can be considered stable under a wide range of temperature and pH, making their removal one of the most difficult tasks in downstream processes during protein purification. The inherent toxicity of LPS makes their removal an important step for the application of these proteins in several biological assays and for a safe parenteral administration. Immobilized metal affinity chromatography (IMAC) enables the affinity interactions between the metal ions (immobilized on the support through the chelating compound) and the target molecules, thus enabling high-efficiency separation of the target molecules from other components present in a mixture. Affinity chromatography is applied with Ca2+ -iminodiacetic acid (IDA) to remove most of the LPS contaminants from the end product (more than 90%). In this study, the adsorption of LPS on an IDA-Ca2+ was investigated. The adsorption Freundlich isotherm of LPS-IDA-Ca2+ provides a theoretical basis for LPS removal. It was found that LPS is bound mainly by interactions between the phosphate group in LPS and Ca2+ ligands on the beads. The factors such as pH (4.0 or 5.5) and ionic strength (1.0 mol/L) are essential to obtain effective removal of LPS for contaminant levels between endotoxin' concentration values less than 100 EU/mL and 100 000 EU/mL. This new protocol represents a substantial advantage in time, effort, and production costs.
Uptake of manganese in potatoes tolerant of high tissue manganese levels
Energy Technology Data Exchange (ETDEWEB)
Marsh, K.B.
1987-01-01
Observations on the accumulations of Mn in potatoes (Solanum tuberosum cv. Norland) focused on factors which enabled plants in field studies to withstand high concentrations of Mn in their foliage. A microculture method for assessing nutrient uptake was introduced and applied to studies of the effects of P and temperature on Mn toxicity. Potato plants in microculture behaved similarly in the symptomatology of Mn toxicity to those grown in solution culture but were more responsive to P. The effects of both P and temperature on Mn toxicity in microculture correlated with changes in Mn uptake and with growth reductions due to low P or temperature stress. The uptake of Mn from solution culture increased with increasing P level in solution. This increase was attributed to an increased health and vitality of potato plants under high P and to changes in pH and nutrient solution concentration as plants matured at different rates. When limited control over solution pH and nutrient concentration was provided the effects of P on Mn uptake were largely eliminated. The well-documented time dependence of Mn accumulation was confirmed in a fractionation experiment.
International Nuclear Information System (INIS)
Duff, M.C.; Crump, S.L.; Ray, R.J.; Beals, D.; Cotham, W.E.; Mount, K.; Koons, R.D.; Leggitt, J.
2008-01-01
The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating high explosive (HE) evidence while maintaining evidentiary value. One experimental method for the isolation of HE residue involves using solid phase microextraction (SPME) fibers to remove residue of interest. Due to their high affinity for organics, SPME fibers should have little affinity for most metals. However, no studies have measured the affinity of radionuclides for SPME fibers. The focus of this research was to examine the affinity of dissolved radionuclide ( 239/240 Pu, 238 U, 237 Np, 85 Sr, 133 Ba, 137 Cs, 60 Co and 226 Ra) and stable radionuclide surrogate metals (Sr, Co, Ir, Re, Ni, Ba, Cs, Nb, Ru, and Nd) for SPME fibers at the exposure conditions that favor the uptake of HE residues. Our results from radiochemical and mass spectrometric analyses indicate these metals have little measurable affinity for these SPME fibers during conditions that are conducive to HE residue uptake with subsequent analysis by liquid or gas phase chromatography with mass spectrometric detection. (author)
Jia, Xiuling; Chen, Dunjun; Bin, Liu; Lu, Hai; Zhang, Rong; Zheng, Youdou
2016-06-09
A novel ion-imprinted electrochemical sensor based on AlGaN/GaN high electron mobility transistors (HEMTs) was developed to detect trace amounts of phosphate anion. This sensor combined the advantages of the ion sensitivity of AlGaN/GaN HEMTs and specific recognition of ion imprinted polymers. The current response showed that the fabricated sensor is highly sensitive and selective to phosphate anions. The current change exhibited approximate linear dependence for phosphate concentration from 0.02 mg L(-1) to 2 mg L(-1), the sensitivity and detection limit of the sensor is 3.191 μA/mg L(-1) and 1.97 μg L(-1), respectively. The results indicated that this AlGaN/GaN HEMT-based electrochemical sensor has the potential applications on phosphate anion detection.
Amyloid-beta binds catalase with high affinity and inhibits hydrogen peroxide breakdown.
Milton, N G
1999-01-01
Amyloid-beta (Abeta) specifically bound purified catalase with high affinity and inhibited catalase breakdown of H(2)O(2). The Abeta-induced catalase inhibition involved formation of the inactive catalase Compound II and was reversible. CatalaseAbeta interactions provide rapid functional assays for the cytotoxic domain of Abeta and suggest a mechanism for some of the observed actions of Abeta plus catalase in vitro.
Dimensional stability under wet curing of mortars containing high amounts of nitrates and phosphates
International Nuclear Information System (INIS)
Benard, P.; Cau Dit Coumes, C.; Garrault, S.; Nonat, A.; Courtois, S.
2008-01-01
Investigations were carried out in order to solidify in cement some aqueous streams resulting from nuclear decommissioning processes and characterized by a high salinity (300 g/L), as well as important concentrations of nitrate (150-210 g/L) and phosphate ions (0-50 g/L). Special attention was paid to the influence of these compounds on the dimensional variations under wet curing of simulated solidified waste forms. The length changes of mortars containing nitrate salts only (KNO 3 , NaNO 3 ) were shown to be governed by a concentration effect which involved osmosis: the higher their concentration in the mixing solution, the higher the swelling. The expansion of mortars containing high amounts of phosphates (≥ 30 g/L in the mixing solution) was preceded by a shrinkage which increased with the phosphate concentration, and which could be suppressed by seeding the cement used with hydroxyapatite crystals. This transitory shrinkage was attributed to the conversion into hydroxyapatite of a precursor readily precipitated in the cement paste after mixing
Unexpectedly high uptake of palladium by bituminous coals
Energy Technology Data Exchange (ETDEWEB)
Lakatos, J. [Research Lab. for Mining Chemistry, Hungarian Academy of Sciences, Miskolc-Egyetemvaros (Hungary); Brown, S.D.; Snape, C.E. [Univ. of Strathclyde, Dept. of Pure and Applied Chemistry, Glasgow (United Kingdom)
1997-12-31
The uptake of palladium as a conversion catalyst onto coals of different rank was investigated. Palladium fixation occurs by a different mode to that for alkaline earth and first row transition metals. Therefore, the dispersion of relatively high concentration of palladium by an ion sorption process is even possible for bituminous coals. (orig.)
Development of nanosensors for studying intracellular phosphate levels
DEFF Research Database (Denmark)
Gu, Hong
-time monitoring of Pi metabolism in living cells, providing a new tool for fluxomics (measurement of metabolic flux), analysis of pathophysiology or changes of Pi during cell activity. Transformation of plants with FLIPs had resulted in only low expression levels. As an alternative a protein transduction domain......Abstract Inorganic phosphate (Pi) is an essential macronutrient that plays a central role in metabolism and signal transduction in plants. Uptake, compartmentation and transport are important players of cellular Pi homeostasis; however, methods to determine the cellular phosphate concentration...... of a substrate-binding protein linked to two fluorescent reporter proteins. Substrate binding changes the conformation of the nanosensor and, hence, the efficiency of fluorescence resonance energy transfer (FRET) between the reporter proteins. The aim of the present project was to develop nanosensors for Pi...
International Nuclear Information System (INIS)
El-Bahi, S.M.; Sroor, A.; Mohamed, Gehan Y.; El-Gendy, N.S.
2017-01-01
In this study, the activity concentrations of the natural radionuclides in phosphate rocks and its products were measured using a high- purity germanium detector (HPGe). The obtained activity results show remarkable wide variation in the radioactive contents for the different phosphate samples. The average activity concentration of "2"3"5U, "2"3"8U, "2"2"6Ra, "2"3"2Th and "4"0K was found as (45, 1031, 786, 85 and 765 Bq/kg) for phosphate rocks, (28, 1234, 457, 123 and 819 Bq/kg) for phosphate fertilizers, (47, 663, 550, 79 and 870 Bq/kg) for phosphogypsum and (25, 543, 409, 54 and 897 Bq/kg) for single super phosphate respectively. Based on the measured activities, the radiological parameters (activity concentration index, absorbed gamma dose rate in outdoor and indoor and the corresponding annual effective dose rates and total excess lifetime cancer risk) were estimated to assess the radiological hazards. The total excess lifetime cancer risk (ELCR) has been calculated and found to be high in all samples, which related to high radioactivity, representing radiological risk for the health of the population. - Highlights: • Level of radioactivity of phosphate rocks and by-products samples. • The radiological health hazard parameters. • Radiological risk to the health of the population. • The excess lifetime cancer risk factor.
Aparecida de França, Suélem; Pavani Dos Santos, Maísa; Nunes Queiroz da Costa, Roger Vinícius; Froelich, Mendalli; Buzelle, Samyra Lopes; Chaves, Valéria Ernestânia; Giordani, Morenna Alana; Pereira, Mayara Peron; Colodel, Edson Moleta; Marlise Balbinotti Andrade, Cláudia; Kawashita, Nair Honda
2014-04-01
The aim of this study was to evaluate glucose uptake and the contribution of glucose to fatty acid (FA) synthesis and the glycerol-3-phosphate (G3P) of triacylglycerol synthesis by interscapular brown adipose tissue (IBAT) of low-protein, high-carbohydrate (LPHC) diet-fed rats. LPHC (6% protein; 74% carbohydrate) or control (17% protein; 63% carbohydrate) diets were administered to rats (∼ 100 g) for 15 d. Total FA and G3P synthesis and the synthesis of FA and G3P from glucose were evaluated in vivo by (3)H2O and (14)C-glucose. Sympathetic neural contribution for FA synthesis was evaluated by comparing the synthesis in denervated (7 d before) IBAT with that of the contralateral innervated side. The insulin signaling and β3 adrenergic receptor (β3-AR) contents, as well as others, were determined by Western blot (Student's t test or analysis of variance; P ≤ 0.05). Total FA synthesis in IBAT was 133% higher in the LPHC group and was reduced 85% and 70% by denervation for the LPHC and control groups, respectively. Glucose uptake was 3.5-fold higher in the IBAT of LPHC rats than in that of the control rats, and the contribution of glucose to the total FA synthesis increased by 12% in control rats compared with 18% in LPHC rats. The LPHC diet increased the G3P generation from glucose by 270% and the insulin receptor content and the p-AKT insulin stimulation in IBAT by 120% and reduced the β3-AR content by 50%. The LPHC diet stimulated glucose uptake, both the total rates and the rates derived from glucose-dependent FA and G3P synthesis, by increasing the insulin sensitivity and the sympathetic flux, despite a reduction in the β3-AR content. Copyright © 2014 Elsevier Inc. All rights reserved.
Mobile Technology Affinity in Renal Transplant Recipients.
Reber, S; Scheel, J; Stoessel, L; Schieber, K; Jank, S; Lüker, C; Vitinius, F; Grundmann, F; Eckardt, K-U; Prokosch, H-U; Erim, Y
Medication nonadherence is a common problem in renal transplant recipients (RTRs). Mobile health approaches to improve medication adherence are a current trend, and several medication adherence apps are available. However, it is unknown whether RTRs use these technologies and to what extent. In the present study, the mobile technology affinity of RTRs was analyzed. We hypothesized significant age differences in mobile technology affinity and that mobile technology affinity is associated with better cognitive functioning as well as higher educational level. A total of 109 RTRs (63% male) participated in the cross-sectional study, with an overall mean age of 51.8 ± 14.2 years. The study included the Technology Experience Questionnaire (TEQ) for the assessment of mobile technology affinity, a cognitive test battery, and sociodemographic data. Overall, 57.4% of the patients used a smartphone or tablet and almost 45% used apps. The TEQ sum score was 20.9 in a possible range from 6 (no affinity to technology) to 30 (very high affinity). Younger patients had significantly higher scores in mobile technology affinity. The only significant gender difference was found in having fun with using electronic devices: Men enjoyed technology more than women did. Mobile technology affinity was positively associated with cognitive functioning and educational level. Young adult patients might profit most from mobile health approaches. Furthermore, high educational level and normal cognitive functioning promote mobile technology affinity. This should be kept in mind when designing mobile technology health (mHealth) interventions for RTRs. For beneficial mHealth interventions, further research on potential barriers and desired technologic features is necessary to adapt apps to patients' needs. Copyright © 2017 Elsevier Inc. All rights reserved.
Identification of high-affinity calmodulin-binding proteins in rat liver
International Nuclear Information System (INIS)
Hanley, R.M.; Dedman, J.R.; Shenolikar, S.
1987-01-01
The Ca 2+ -dependent binding of [ 125 I] calmodulin (CaM) to hepatic proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was utilized to identify CaM binding or acceptor proteins or CAPs. Two proteins of apparent molecular weight of 60,000 (CAP-60) and 45,000 (CAP-45) comprised > 80% of the Ca 2+ -dependent CaM binding in rat liver cytosol. CAP-60 and CAP-45 were partially purified by a variety of chromatographic steps, including affinity chromatography on CaM Sepharose. CAP-60 possessed a native molecular size of 400,000, indicating it to be the CaM-binding subunit of a larger oligomeric complex. In contrast, CAP-45 was monomeric as judged by gel filtration. Neither CAP-60 nor CAP-45 possessed chromatographic properties consistent with known CaM-dependent enzymes reported in the literature. Two-dimensional peptide mapping provided convincing evidence that CAP-60 and CAP-45 were unrelated to other well-characterized CAPs, namely Ca 2+ (CaM)-dependent protein kinase II, calcineurin, or the CaM-dependent cyclic nucleotide phosphodiesterase. The relative abundance and high affinity for CaM could suggest that these novel target proteins, CAP-60 and CAP-45, represent a dominant pathway for CaM action in the mammalian liver
Lin, Qingqi; Yang, Xiuhong; Huang, Xiongfei; Wang, Shizhong; Chao, Yuanqing; Qiu, Rongliang
2016-01-01
Phthalate acid esters (PAEs) are of particular concern due to their potential environmental risk to human and nonhuman organisms. Although uptake of PAEs by plants has been reported by several researchers, information about the intracellular distribution and uptake mechanisms of PAEs is still lacking. In this study, a series of hydroponic experiments using intact pumpkin (Cucurbita moschata) seedlings was conducted to investigate how di-n-butyl phthalate (DnBP), one of the most frequently identified PAEs in the environment, enters and is distributed in roots. DnBP was transported into subcellular tissues rapidly in the initial uptake period (<12 h). More than 80% of DnBP was detected in the cell walls and organelles, which suggests that DnBP is primarily accumulated in these two fractions due to their high affinity to DnBP. The kinetics of DnBP uptake were fitted well with the Michaelis-Menten equation, suggesting that a carrier-mediated process was involved. The application of 2,4-dinitrophenol and sodium vanadate reduced the uptake of DnBP by 37 and 26%, respectively, while aquaporin inhibitors, silver and glycerol, had no effect on DnBP uptake. These data demonstrated that the uptake of DnBP included a carrier-mediated and energy-dependent process without the participation of aquaporins.
Uptake of fertilizer phosphorus by three rice varieties in a vertisol
International Nuclear Information System (INIS)
Sinha, S.B.; Rastogi, A.K.; Mahajan, J.P.
1980-01-01
A pot experiment was conducted using labelled super-phosphate to study the utilization of fertilizer phosphorus by three paddy varieties, viz, Jaya, Ratna and Sona. Total P uptake and P derived from fertilizer, increased significantly with increasing levels of P applied (0 to 90 kg P 2 O 5 /ha), while the percent utilization of applied P showed a reverse trend. Straw and grain yield, in general, increased significantly with increasing P levels in all the three varieties. Average soil P uptake in grain and straw decreased with increasing levels of applied phosphorus. (author)
Water uptake and motion in highly densified bentonite
International Nuclear Information System (INIS)
Kahr, G.; Mueller-Vonmoos, F.; Kraehenbuehl, F.; Stoeckli, H.F.
1986-07-01
Water uptake by the bentonites MX-80 and Montigel was investigated according to the classical method of determination of the heat immersion and the adsorption-desorption isotherms. In addition, the layer expansion of the montmorillonite was measured as a function of the water content. The evaluation of the adsorption isotherms according to Dubinin-Radushkevich and the stratification distances determined by x-ray confirmed gradual water uptake. Up to 10% water content, the water is adsorbed as a monolayer, up to 20%, as a bimolecular layer around the interlayer cations. The partial specific entropy could be determined from the approximative calculation of the partial specific enthalpy from the heats of immersion and the free enthalpy from the adsorption isotherms. From this it is evident that the interlayer water shows a high degree of order. In this condition, the mobility of the water molecules is considerably lower than in free water. From the adsorption isotherm and the layer expansion observed, it can be assumed that water can appear in the pore space only from approximately 25% water content. The spaces outwith the interlayer space and the surfaces of the montmorillonite particles are considered as pore space. If free swelling is prevented and with dry densities greater than 1.8 Mg/m/sup 3/ for the highly compacted bentonites, water uptake causes a drastic reduction of the original pore space so that practically all the water is in the interlayer space. Calculation of the swelling pressure from the adsorption isotherms gives a good approximation of the measured swelling pressures. A montmorillonite surface of ca. 750 m/sup 2//g for both bentonites can be derived from a Dubinin-Radushkevich analysis of the adsorption isotherm. Water uptake into the compacted unsaturated bentonites can be described as diffusion with a diffusion coefficient of the order of magnitude of 3.10/sup -10/ m/sup 2//s. (author)
International Nuclear Information System (INIS)
Carlier, M.F.; Didry, D.; Melki, R.; Chabre, M.; Pantaloni, D.
1988-01-01
In order to elucidate how the elementary reactions of GTP cleavage and subsequent inorganic phosphate (P/sub i/) release, which accompany microtubule assembly, regulate microtubule dynamics, the effect of P/sub i/ and of its structural analogues AlF 4 - and BeF 3 - on the stability of GDP-microtubules has been investigated. Inorganic phosphate binds to microtubules with a low affinity (K/sub D/ = 25 mM) and slows down the rate of GDP-subunit dissociation by about 2 orders of magnitude. AlF 4 - and BeF 3 - exhibit phosphate-like effects with 1000-fold higher affinity. Evidence has been obtained for direct binding of BeF 3 - to microtubules with a stoichiometry of 1 mol of BeF 3 - per mole of GDP-subunit and an equilibrium dissociation constant of 12-15 μM. AlF 4 - and P/sub i/ compete for this site. Phosphate analogues abolish oscillatory polymerization kinetics and slow down microtubule turnover at steady state. In view of these results, the authors propose that P/sub i/ and its structural analogues bind to the site of the γ-phosphate of GTP in the E site and reconstitute a GDP-P/sub i/-microtubule, from which tubulin subunits dissociate very slowly. They therefore understand that, following GTP cleavage on microtubules, P/sub i/ release in the medium is accompanied by a structural change resulting in a large destabilization of the polymer. A cap of slowly dissociating GDP-P/sub i/-subunits prevents depolymerization of the microtubule GDP-core at steady state. The similarity with the actin system is studied
Localised uptake and extraction of calcium45 in dinoflagellate nuclei
International Nuclear Information System (INIS)
Sigee, D.C.
1983-01-01
The uptake of Ca 45 into cells of the dinoflagellate Glenodinium foliaceum was investigated using insoluble compound light microscope autoradiography. The distribution of silver grains showed marked localisation to the dinocaryotic nucleus, with a random scatter of grains over the surrounding protoplasm (cytoplasm and supernumerary nucleus). Correction of grain counts for lateral sensitisation from the dinocaryotic nucleus indicated an isotope concentration 16 32 times greater in this organelle compared to the rest of the cell. Cells labelled for varying periods of time showed differences in the pattern of Ca 45 uptake throughout the sample populations, but no increase in the mean level of uptake per cell. This would suggest a rapid incorporation of isotope within 1-2 hours, with little subsequent uptake. The presence of high levels of label after processing with both additive (glutaraldehyde, paraformaldehyde) and coagulative (acetic alcohol) fixatives indicated that the retention of Ca 45 in these preparations was not simply a fixation artefact. Although the isotope did not appear to be suitable for (high resolution) electron microscope autoradiography, the intranuclear site of incorporation was demonstrated indirectly using a buffer extraction technique. Prolonged treatment with phosphate buffer resulted in a large scale loss of label from both cytoplasm and dinocaryotic nucleus. The latter appeared to show specific correlation with the loss of (protein) matrix from the chromosomes - as observed under both light and electron microscopy, with no apparent change in either nucleolus or nucleoplasm. This would suggest that incorporated Ca 45 in the nucleus was largely confined to the condensed chromatin, where it was combined with the acidic proteins which make up the bulk of the chromatin matrix. The results obtained in this investigation are related to previous studies involving X-ray microanalysis and uptake of Ni 63 . (Author)
Antibody Binding Selectivity: Alternative Sets of Antigen Residues Entail High-Affinity Recognition.
Directory of Open Access Journals (Sweden)
Yves Nominé
Full Text Available Understanding the relationship between protein sequence and molecular recognition selectivity remains a major challenge. The antibody fragment scFv1F4 recognizes with sub nM affinity a decapeptide (sequence 6TAMFQDPQER15 derived from the N-terminal end of human papilloma virus E6 oncoprotein. Using this decapeptide as antigen, we had previously shown that only the wild type amino-acid or conservative replacements were allowed at positions 9 to 12 and 15 of the peptide, indicating a strong binding selectivity. Nevertheless phenylalanine (F was equally well tolerated as the wild type glutamine (Q at position 13, while all other amino acids led to weaker scFv binding. The interfaces of complexes involving either Q or F are expected to diverge, due to the different physico-chemistry of these residues. This would imply that high-affinity binding can be achieved through distinct interfacial geometries. In order to investigate this point, we disrupted the scFv-peptide interface by modifying one or several peptide positions. We then analyzed the effect on binding of amino acid changes at the remaining positions, an altered susceptibility being indicative of an altered role in complex formation. The 23 starting variants analyzed contained replacements whose effects on scFv1F4 binding ranged from minor to drastic. A permutation analysis (effect of replacing each peptide position by all other amino acids except cysteine was carried out on the 23 variants using the PEPperCHIP® Platform technology. A comparison of their permutation patterns with that of the wild type peptide indicated that starting replacements at position 11, 12 or 13 modified the tolerance to amino-acid changes at the other two positions. The interdependence between the three positions was confirmed by SPR (Biacore® technology. Our data demonstrate that binding selectivity does not preclude the existence of alternative high-affinity recognition modes.
International Nuclear Information System (INIS)
Lambeau, G.; Barhanin, J.; Schweitz, H.; Qar, J.; Lazdunski, M.
1989-01-01
Four new monochain phospholipases were purified from the Oxyuranus scutellatus (taipan) venom. Three of them were highly toxic when injected into mice brain. One of these neurotoxic phospholipases, OS2, was iodinated and used in binding experiments to demonstrate the presence of two families of specific binding sites in rat brain synaptic membranes. The affinities were exceptionally high, Kd1 = 1.5 +/- 0.5 pM and Kd2 = 45 +/- 10 pM, and the maximal binding capacities were Bmax 1 = 1 +/- 0.4 and Bmax 2 = 3 +/- 0.5 pmol/mg of protein. Both binding sites were sensitive to proteolysis and demonstrated to be located on proteins of Mr 85,000-88,000 and 36,000-51,000 by cross-linking and photoaffinity labeling techniques. The binding of 125 I-OS2 to synaptic membranes was dependent on Ca2+ ions and enhanced by Zn2+ ions which inhibit phospholipase activity. Competition experiments have shown that, except for beta-bungarotoxin, a number of known toxic snake or bee phospholipases have very high affinities for the newly identified binding sites. A good correlation (r = 0.80) was observed between toxicity and affinity but not between phospholipase activity and affinity
The utility of affine variables and affine coherent states
International Nuclear Information System (INIS)
Klauder, John R
2012-01-01
Affine coherent states are generated by affine kinematical variables much like canonical coherent states are generated by canonical kinematical variables. Although all classical and quantum formalisms normally entail canonical variables, it is shown that affine variables can serve equally well for many classical and quantum studies. This general purpose analysis provides tools to discuss two major applications: (1) the completely successful quantization of a nonrenormalizable scalar quantum field theory by affine techniques, in complete contrast to canonical techniques which only offer triviality; and (2) a formulation of the kinematical portion of quantum gravity that favors affine kinematical variables over canonical kinematical variables, and which generates a framework in which a favorable analysis of the constrained dynamical issues can take place. All this is possible because of the close connection between the affine and the canonical stories, while the few distinctions can be used to advantage when appropriate. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’. (review)
Twins in spirit part II: DOTATATE and high-affinity DOTATATE - the clinical experience
Energy Technology Data Exchange (ETDEWEB)
Brogsitter, Claudia; Zoephel, Klaus; Hartmann, Holger; Kotzerke, Joerg [Technische Universitaet Dresden, Department of Nuclear Medicine, Dresden (Germany); Schottelius, Margret; Wester, Hans-Juergen [Technische Universitaet Muenchen, Pharmaceutical Radiochemistry and Department of Nuclear Medicine, Muenchen (Germany)
2014-06-15
Over recent decades interest in diagnosis and treatment of neuroendocrine tumours (NET) has steadily grown. The basis for diagnosis and therapy of NET with radiolabelled somatostatin (hsst) analogues is the variable overexpression of hsst receptors (hsst1-5 receptors). We hypothesized that radiometal derivatives of DOTA-iodo-Tyr{sup 3}-octreotide analogues might be excellent candidates for somatostatin receptor imaging. We therefore explored the diagnostic potential of {sup 68}Ga-DOTA-iodo-Tyr{sup 3}-octreotate [{sup 68}Ga-DOTA,3-iodo-Tyr{sup 3},Thr{sup 8}]octreotide ({sup 68}Ga-HA-DOTATATE; HA, high-affinity) compared to the established {sup 68}Ga-DOTA-Tyr{sup 3}-octreotate ({sup 68}Ga-DOTATATE) in vivo. The study included 23 patients with known somatostatin receptor-positive metastases from NETs, thyroid cancer or glomus tumours who were investigated with both {sup 68}Ga-HA-DOTATATE and {sup 68}Ga-DOTATATE. A patient-based and a lesion-based comparative analysis was carried out of normal tissue distribution and lesion detectability in a qualitative and a semiquantitative manner. {sup 68}Ga-HA-DOTATATE and {sup 68}Ga-DOTATATE showed comparable uptake in the liver (SUV{sub mean} 8.9 ± 2.2 vs. 9.3 ± 2.5, n.s.), renal cortex (SUV{sub mean} 13.3 ± 3.9 vs. 14.5 ± 3.7, n.s.) and spleen (SUV{sub mean} 24.0 ± 6.7 vs. 22.9 ± 7.3, n.s.). A somewhat higher pituitary uptake was found with {sup 68}Ga-HA-DOTATATE (SUV{sub mean} 6.3 ± 1.8 vs. 5.4 ± 2.1, p < 0.05). On a lesion-by-lesion basis a total of 344 lesions were detected. {sup 68}Ga-HA-DOTATATE demonstrated 328 lesions (95.3 % of total lesions seen), and {sup 68}Ga-DOTATATE demonstrated 332 lesions (96.4 %). The mean SUV{sub max} of all lesions was not significantly different between {sup 68}Ga-HA-DOTATATE and {sup 68}Ga-DOTATATE (17.8 ± 11.4 vs. 16.7 ± 10.7, n.s.). Our analysis demonstrated very good concordance between {sup 68}Ga-HA-DOTATATE and {sup 68}Ga-DOTATATE PET data. As the availability and use of {sup
Critical role of γ-phosphate in structural transition of Na,K-ATPase upon ATP binding
Petrushanko, Irina Yu.; Mitkevich, Vladimir A.; Anashkina, Anastasia A.; Klimanova, Elizaveta A.; Dergousova, Elena A.; Lopina, Olga D.; Makarov, Alexander A.
2014-06-01
Active transport of sodium and potassium ions by Na,K-ATPase is accompanied by the enzyme conformational transition between E1 and E2 states. ATP and ADP bind to Na,K-ATPase in the E1 conformation with similar affinity but the properties of enzyme in complexes with these nucleotides are different. We have studied thermodynamics of Na,K-ATPase binding with adenine nucleotides at different temperatures using isothermal titration calorimetry. Our data indicate that β-phosphate is involved in complex formation by increasing the affinity of adenine nucleotides to Na,K-ATPase by an order of magnitude, while γ-phosphate does not affect it. ATP binding to Na,K-ATPase in contrast to ADP binding generates a structural transition in the enzyme, which is consistent with the movement of a significant portion of the surface area to a solvent-protected state. We propose that ATP binding leads to convergence of the nucleotide-binding and phosphorylation domains transferring the enzyme from the ``E1-open'' to ``E1-closed'' conformation ready for phosphorylation.
Selection of imprinted nanoparticles by affinity chromatography.
Guerreiro, António R; Chianella, Iva; Piletska, Elena; Whitcombe, Michael J; Piletsky, Sergey A
2009-04-15
Soluble molecularly imprinted nanoparticles were synthesised via iniferter initiated polymerisation and separated by size via gel permeation chromatography. Subsequent fractionation of these particles by affinity chromatography allowed the separation of high affinity fractions from the mixture of nanoparticles. Fractions selected this way possess affinity similar to that of natural antibodies (K(d) 6.6x10(-8)) M and were also able to discriminate between related functional analogues of the template.
Energy Technology Data Exchange (ETDEWEB)
Isales, Gregory M.; Hipszer, Rachel A.; Raftery, Tara D. [Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC (United States); Chen, Albert; Stapleton, Heather M. [Division of Environmental Sciences and Policy, Nicholas School of the Environment, Duke University, Durham, NC (United States); Volz, David C., E-mail: volz@mailbox.sc.edu [Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC (United States)
2015-04-15
Highlights: • Triphenyl phosphate-induced toxicity in zebrafish embryos is enhanced in the presence of a retinoic acid receptor antagonist. • Triphenyl phosphate uptake or metabolism within zebrafish embryos is not altered in the presence of a retinoic acid receptor antagonist. • Triphenyl phosphate decreases expression of cytochrome P450 26a1 in zebrafish embryos. • Triphenyl phosphate inhibits retinoic acid-induced activation of human retinoic acid receptors. - Abstract: Using zebrafish as a model, we previously reported that developmental exposure to triphenyl phosphate (TPP) – a high-production volume organophosphate-based flame retardant – results in dioxin-like cardiac looping impairments that are independent of the aryl hydrocarbon receptor. Using a pharmacologic approach, the objective of this study was to investigate the potential role of retinoic acid receptor (RAR) – a nuclear receptor that regulates vertebrate heart morphogenesis – in mediating TPP-induced developmental toxicity in zebrafish. We first revealed that static exposure of zebrafish from 5–72 h post-fertilization (hpf) to TPP in the presence of non-toxic concentrations of an RAR antagonist (BMS493) significantly enhanced TPP-induced toxicity (relative to TPP alone), even though identical non-toxic BMS493 concentrations mitigated retinoic acid (RA)-induced toxicity. BMS493-mediated enhancement of TPP toxicity was not a result of differential TPP uptake or metabolism, as internal embryonic doses of TPP and diphenyl phosphate (DPP) – a primary TPP metabolite – were not different in the presence or absence of BMS493. Using real-time PCR, we then quantified the relative change in expression of cytochrome P450 26a1 (cyp26a1) – a major target gene for RA-induced RAR activation in zebrafish – and found that RA and TPP exposure resulted in a ∼5-fold increase and decrease in cyp26a1 expression, respectively, relative to vehicle-exposed embryos. To address whether TPP may
Abate, Carmen; Hornick, John R; Spitzer, Dirk; Hawkins, William G; Niso, Mauro; Perrone, Roberto; Berardi, Francesco
2011-08-25
Fluorescent derivatives of σ(2) high affinity ligand 1-cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl)propyl]piperazine 1 (PB28) were synthesized. NBD or dansyl fluorescent tags were connected through a 5- or 6-atom linker in two diverse positions of 1 structure. Good σ(2) affinities were obtained when the fluorescent tag was linked to 5-methoxytetralin nucleus replacing the methyl function. NBD-bearing compound 16 displayed high σ(2) affinity (K(i) = 10.8 nM) and optimal fluorescent properties. Its uptake in pancreatic tumor cells was evaluated by flow cytometry, showing that it partially occurs through endocytosis. In proliferating cells, the uptake was higher supporting that σ(2) receptors are markers of cell proliferation and that the higher the proliferation is, the stronger the antiproliferative effect of σ(2) agonists is. Colocalization of 16 with subcellular organelles was studied by confocal microscopy: the greatest was in endoplasmic reticulum and lysosomes. Fluorescent σ(2) ligands show their potential in clarifying the mechanisms of action of σ(2) receptors. © 2011 American Chemical Society
Structural insights into a high affinity nanobody:antigen complex by homology modelling
DEFF Research Database (Denmark)
Skottrup, Peter Durand
2017-01-01
Porphyromonas gingivalis is a major periodontitis-causing pathogens. P. gingivalis secrete a cysteine protease termed RgpB, which is specific for Arg-Xaa bonds in substrates. Recently, a nanobody-based assay was used to demonstrate that RgpB could represent a novel diagnostic target, thereby...... simplifying. P. gingivalis detection. The nanobody, VHH7, had a high binding affinity and was specific for RgpB, when tested towards the highly identical RgpA. In this study a homology model of VHH7 was build. The complementarity determining regions (CDR) comprising the paratope residues responsible for Rgp...
A mathematical model for investigating the effect of cluster roots on plant nutrient uptake
Zygalakis, K. C.; Roose, T.
2012-01-01
phase and can also solubilised due to citrate exudation. Using multiple scale homogenisation techniques we derive an effective model that accounts for the cumulative effect of citrate exudation and phosphate uptake by cluster roots whilst still retaining
Alternative affinity tools: more attractive than antibodies?
Ruigrok, V.J.B.; Levisson, M.; Eppink, M.H.M.; Smidt, H.; Oost, van der J.
2011-01-01
Antibodies are the most successful affinity tools used today, in both fundamental and applied research (diagnostics, purification and therapeutics). Nonetheless, antibodies do have their limitations, including high production costs and low stability. Alternative affinity tools based on nucleic acids
Energy Technology Data Exchange (ETDEWEB)
Haag, R
1975-01-01
Infarction-like or disseminated myocardial necroses can be produced in rats by high doses of isoprotenerol which stimulates the decomposition of energy-rich phosphates to a maximum. The paper shows that acidoses of different genesis (peroral administration of NH/sub 4/Cl, artificial respiration with CO/sub 2/) induced experimentally can inhibit the isoproterenol-induced /sup 45/Ca net uptake and the production of necroses. The findings suggest that Ca/sup + +/ ions play a key role in the production of myocardial necroses which has not been recognized until now - that increased Ca/sup + +/ uptake into damaged myocardial fibres is a result or, at the most, an accompanying symptom of necrosis production - should therefore be discarded.
McDonald, Charles J; Acheff, Eric; Kennedy, Ryan; Taylor, Lynn; Curthoys, Norman P
2015-09-01
The GLS1 gene encodes a mitochondrial glutaminase that is highly expressed in brain, kidney, small intestine and many transformed cells. Recent studies have identified multiple lysine residues in glutaminase that are sites of N-acetylation. Interestingly, these sites are located within either a loop segment that regulates access of glutamine to the active site or the dimer:dimer interface that participates in the phosphate-dependent oligomerization and activation of the enzyme. These two segments also contain the binding sites for bis-2[5-phenylacetamido-1,2,4-thiadiazol-2-yl]ethylsulfide (BPTES), a highly specific and potent uncompetitive inhibitor of this glutaminase. BPTES is also the lead compound for development of novel cancer chemotherapeutic agents. To provide a preliminary assessment of the potential effects of N-acetylation, the corresponding lysine to alanine mutations were constructed in the hGACΔ1 plasmid. The wild type and mutated proteins were purified by Ni(+)-affinity chromatography and their phosphate activation and BPTES inhibition profiles were analyzed. Two of the alanine substitutions in the loop segment (K311A and K328A) and the one in the dimer:dimer interface (K396A) form enzymes that require greater concentrations of phosphate to produce half-maximal activation and exhibit greater sensitivity to BPTES inhibition. By contrast, the K320A mutation results in a glutaminase that exhibits near maximal activity in the absence of phosphate and is not inhibited by BPTES. Thus, lysine N-acetylation may contribute to the acute regulation of glutaminase activity in various tissues and alter the efficacy of BPTES-type inhibitors. Copyright © 2014 Elsevier Ltd. All rights reserved.
DEFF Research Database (Denmark)
Hespel, P; Richter, Erik
1990-01-01
1. Glucose uptake and transport, muscle glycogen, free glucose and glucose-6-phosphate concentrations were studied in perfused resting and contracting rat skeletal muscle with different pre-contraction glycogen concentrations. Rats were pre-conditioned by a combination of swimming exercise and diet......, resulting in either low (glycogen-depleted rats), normal (control rats) or high (supercompensated rats) muscle glycogen concentrations at the time their hindlimbs were perfused. 2. Compared with control rats, pre-contraction muscle glycogen concentration was approximately 40% lower in glycogen-depleted rats......, whereas it was 40% higher in supercompensated rats. Muscle glycogen break-down correlated positively (r = 0.76; P less than 0.001) with pre-contraction muscle glycogen concentration. 3. Glucose uptake during contractions was approximately 50% higher in glycogen-depleted hindquarters than in control...
Zeilinger, Markus; Dumanic, Monika; Pichler, Florian; Budinsky, Lubos; Wadsak, Wolfgang; Pallitsch, Katharina; Spreitzer, Helmut; Lanzenberger, Rupert; Hacker, Marcus; Mitterhauser, Markus; Philippe, Cécile
2017-08-14
The MCHR1 is involved in the regulation of energy homeostasis and changes of the expression are linked to a variety of associated diseases, such as diabetes and adiposity. The study aimed at the in vitro and in vivo evaluation of [ 11 C]SNAP-7941 and [ 18 F]FE@SNAP as potential PET-tracers for the MCHR1. Competitive binding studies with non-radioactive derivatives and small-animal PET/CT and MRI brain studies were performed under baseline conditions and tracer displacement with the unlabelled MCHR1 antagonist (±)-SNAP-7941. Binding studies evinced high binding affinity of the non-radioactive derivatives. Small-animal imaging of [ 11 C]SNAP-7941 and [ 18 F]FE@SNAP evinced high tracer uptake in MCHR1-rich regions of the ventricular system. Quantitative analysis depicted a significant tracer reduction after displacement with (±)-SNAP-7941. Due to the high binding affinity of the non-labelled derivatives and the high specific tracer uptake of [ 11 C]SNAP-7941 and [ 18 F]FE@SNAP, there is strong evidence that both radiotracers may serve as highly suitable agents for specific MCHR1 imaging.
Cao, Yachao; Elmahdy, Akram; Zhu, Hanjiang; Hui, Xiaoying; Maibach, Howard
2018-05-01
Six chemical warfare agent simulants (trimethyl phosphate, dimethyl adipate, 2-chloroethyl methyl sulfide, diethyl adipate, chloroethyl phenyl sulfide and diethyl sebacate) were studied in in vitro human skin to explore relationship between dermal penetration/absorption and the mechanisms of simulant partitioning between stratum corneum (SC) and water as well as between dermal decontamination gel (DDGel) and water. Both binding affinity to and decontamination of simulants using DDGel were studied. Partition coefficients of six simulants between SC and water (Log P SC/w ) and between DDGel and water (Log P DDGel/w ) were determined. Results showed that DDGel has a similar or higher binding affinity to each simulant compared to SC. The relationship between Log P octanol/water and Log P SC/w as well as between Log P octanol/water and Log P DDGel/w demonstrated that partition coefficient of simulants correlated to their lipophilicity or hydrophilicity. Decontamination efficiency results with DDGel for these simulants were consistent with binding affinity results. Amounts of percentage dose of chemicals in DDGel of trimethyl phosphate, dimethyl adipate, 2-chloroethyl methyl sulfide, diethyl adipate, chloroethyl phenyl sulfide and diethyl sebacate were determined to be 61.15, 85.67, 75.91, 53.53, 89.89 and 76.58, with corresponding amounts absorbed in skin of 0.96, 0.65, 1.68, 0.72, 0.57 and 1.38, respectively. In vitro skin decontamination experiments coupled with a dermal absorption study demonstrated that DDGel can efficiently remove chemicals from skin surface, back-extract from the SC, and significantly reduced chemical penetration into skin or systemic absorption for all six simulants tested. Therefore, DDGel offers a great potential as a NextGen skin Decon platform technology for both military and civilian use. Copyright © 2018 John Wiley & Sons, Ltd.
Report: Affinity Chromatography.
Walters, Rodney R.
1985-01-01
Supports, affinity ligands, immobilization, elution methods, and a number of applications are among the topics considered in this discussion of affinity chromatography. An outline of the basic principles of affinity chromatography is included. (JN)
Influence of calcium on ceramide-1-phosphate monolayers
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Joana S. L. Oliveira
2016-02-01
Full Text Available Ceramide-1-phosphate (C1P plays an important role in several biological processes, being identified as a key regulator of many protein functions. For instance, it acts as a mediator of inflammatory responses. The mediation of the inflammation process happens due to the interaction of C1P with the C2 domain of cPLA2α, an effector protein that needs the presence of submicromolar concentrations of calcium ions. The aim of this study was to determine the phase behaviour and structural properties of C1P in the presence and absence of millimolar quantities of calcium in a well-defined pH environment. For that purpose, we used monomolecular films of C1P at the soft air/liquid interface with calcium ions in the subphase. The pH was varied to change the protonation degree of the C1P head group. We used surface pressure versus molecular area isotherms coupled with other monolayer techniques as Brewster angle microscopy (BAM, infrared reflection–absorption spectroscopy (IRRAS and grazing incidence X-ray diffraction (GIXD. The isotherms indicate that C1P monolayers are in a condensed state in the presence of calcium ions, regardless of the pH. At higher pH without calcium ions, the monolayer is in a liquid-expanded state due to repulsion between the negatively charged phosphate groups of the C1P molecules. When divalent calcium ions are added, they are able to bridge the highly charged phosphate groups, enhancing the regular arrangement of the head groups. Similar solidification of the monolayer structure can be seen in the presence of a 150 times larger concentration of monovalent sodium ions. Therefore, calcium ions have clearly a strong affinity for the phosphomonoester of C1P.
Extremely High Phosphate Sorption Capacity in Cu-Pb-Zn Mine Tailings.
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Longbin Huang
Full Text Available Elevated inorganic phosphate (Pi concentrations in pore water of amended tailings under direct revegetation may cause toxicity in some native woody species but not native forbs or herb species, all of which are key constituents in target native plant communities for phytostabilizing base metal mine tailings. As a result, Pi sorption capacity has been quantified by a conventional batch procedure in three types of base metal mine tailings sampled from two copper (Cu-lead (Pb-zinc (Zn mines, as the basis for Pi-fertiliser addition. It was found that the Pi-sorption capacity in the tailings and local soil was extremely high, far higher than highly weathered agricultural soils in literature, but similar to those of volcanic ash soils. The Langmuir P-sorption maximum was up to 7.72, 4.12, 4.02 and 3.62 mg P g-1 tailings, in the fresh tailings of mixed Cu-Pb-Zn streams (MIMTD7, the weathered tailings of mixed Cu-Pb-Zn streams (MIMTD5, EHM-TD (fresh Cu-stream, high magnetite content and local soil (weathered shale and schist, respectively. Physicochemical factors highly correlated with the high Pi-sorption in the tailings were fine particle distribution, oxalate and dithionite-citrate-bicarbonate extractable Fe (FeO and Fed, oxalate-extractable Al and Mn, and the levels of soluble Cd and Zn, and total S and Fe. Large amounts of amorphous Fe oxides and oxyhydroxides may have been formed from the oxidation of pyritic materials and redox cycles of Fe-minerals (such as pyrite (FeS2, ankerite (Ca(Fe Mg(CO32 and siderite (FeCO3, as indicated by the extractable FeO values. The likely formation of sparingly soluble Zn-phosphate in the Pb-Zn tailings containing high levels of Zn (from sphalerite ((Zn,FeS, ZnS, (Zn,CdS may substantially lower soluble Zn levels in the tailings through high rates of Pi-fertiliser addition. As a result, the possibility of P-toxicity in native plant species caused by the addition of soluble phosphate fertilizers would be minimal.
Pei, Laming; Wang, Jiemin; Li, Kunpeng; Li, Yongjun; Li, Bei; Gao, Feng; Yang, Aifang
2012-01-01
Low phosphate availability is a major constraint on plant growth and agricultural productivity. Engineering a crop with enhanced low phosphate tolerance by transgenic technique could be one way of alleviating agricultural losses due to phosphate deficiency. In this study, we reported that transgenic maize plants that overexpressed the Thellungiella halophila vacuolar H+-pyrophosphatase gene (TsVP) were more tolerant to phosphate deficit stress than the wild type. Under phosphate sufficient conditions, transgenic plants showed more vigorous root growth than the wild type. When phosphate deficit stress was imposed, they also developed more robust root systems than the wild type, this advantage facilitated phosphate uptake, which meant that transgenic plants accumulated more phosphorus. So the growth and development in the transgenic maize plants were not damaged as much as in the wild type plants under phosphate limitation. Overexpression of TsVP increased the expression of genes involved in auxin transport, which indicated that the development of larger root systems in transgenic plants might be due in part to enhanced auxin transport which controls developmental events in plants. Moreover, transgenic plants showed less reproductive development retardation and a higher grain yield per plant than the wild type plants when grown in a low phosphate soil. The phenotypes of transgenic maize plants suggested that the overexpression of TsVP led to larger root systems that allowed transgenic maize plants to take up more phosphate, which led to less injury and better performance than the wild type under phosphate deficiency conditions. This study describes a feasible strategy for improving low phosphate tolerance in maize and reducing agricultural losses caused by phosphate deficit stress. PMID:22952696
Hall, Justin; Brault, Amy; Vincent, Fabien; Weng, Shawn; Wang, Hong; Dumlao, Darren; Aulabaugh, Ann; Aivazian, Dikran; Castro, Dana; Chen, Ming; Culp, Jeffrey; Dower, Ken; Gardner, Joseph; Hawrylik, Steven; Golenbock, Douglas; Hepworth, David; Horn, Mark; Jones, Lyn; Jones, Peter; Latz, Eicke; Li, Jing; Lin, Lih-Ling; Lin, Wen; Lin, David; Lovering, Frank; Niljanskul, Nootaree; Nistler, Ryan; Pierce, Betsy; Plotnikova, Olga; Schmitt, Daniel; Shanker, Suman; Smith, James; Snyder, William; Subashi, Timothy; Trujillo, John; Tyminski, Edyta; Wang, Guoxing; Wong, Jimson; Lefker, Bruce; Dakin, Leslie; Leach, Karen
2017-01-01
Cyclic GMP-AMP synthase (cGAS) initiates the innate immune system in response to cytosolic dsDNA. After binding and activation from dsDNA, cGAS uses ATP and GTP to synthesize 2', 3' -cGAMP (cGAMP), a cyclic dinucleotide second messenger with mixed 2'-5' and 3'-5' phosphodiester bonds. Inappropriate stimulation of cGAS has been implicated in autoimmune disease such as systemic lupus erythematosus, thus inhibition of cGAS may be of therapeutic benefit in some diseases; however, the size and polarity of the cGAS active site makes it a challenging target for the development of conventional substrate-competitive inhibitors. We report here the development of a high affinity (KD = 200 nM) inhibitor from a low affinity fragment hit with supporting biochemical and structural data showing these molecules bind to the cGAS active site. We also report a new high throughput cGAS fluorescence polarization (FP)-based assay to enable the rapid identification and optimization of cGAS inhibitors. This FP assay uses Cy5-labelled cGAMP in combination with a novel high affinity monoclonal antibody that specifically recognizes cGAMP with no cross reactivity to cAMP, cGMP, ATP, or GTP. Given its role in the innate immune response, cGAS is a promising therapeutic target for autoinflammatory disease. Our results demonstrate its druggability, provide a high affinity tool compound, and establish a high throughput assay for the identification of next generation cGAS inhibitors.
Sorption of phosphates and thiocyanates on isomorphic substituted Mg/Zn–Al-type hydrotalcites
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RODICA PODE
2008-08-01
Full Text Available The sorption equilibriums of phosphate and thiocyanate anions on isomorphic substituted Mg/Zn–Al-type hydrotalcites were investigated in this study. Langmuir and Freundlich isotherms were used to interpret the equilibrium data for phosphate. The sorption equilibriums of phosphate on Mg3Al, Mg2ZnAl and Mg1.5Zn1.5Al hydrotalcites were well described by the Langmuir isotherm. The highest maximum sorption capacities for these adsorbents were as follows: 111, 101 and 95 mg g-1. The equilibrium constant and standard Gibbs energy changes were also calculated from the sorption data. Standard Gibbs energy changes of about –20 kJ mol-1 indicated that the process might be considered as physical adsorption. The sorption equilibriums of phosphate on isomorphic substituted samples of MgZn2Al and Zn3Al were well described by the Freundlich isotherm. Thiocyanate showed a relative low affinity for the studied materials, as indicated by both the “S”-shaped isotherms and low sorption capacities. The sorption of phosphate and thiocyanate on the investigated hydrotalcites showed a continuous decrease of the sorption capacity in the following order: Mg3Al > Mg2ZnAl > Mg1.5Zn1.5Al > MgZn2Al > Zn3Al.
International Nuclear Information System (INIS)
Ochsenfeld, W.; Schmieder, H.
1976-01-01
Fast breeder fuel elements which have been highly burnt-up are reprocessed by extracting uranium and plutonium into an organic solution containing tributyl phosphate. The tributyl phosphate degenerates at least partially into dibutyl phosphate and monobutyl phosphate, which form stable complexes with tetravalent plutonium in the organic solution. This tetravalent plutonium is released from its complexed state and stripped into aqueous phase by contacting the organic solution with an aqueous phase containing tetravalent uranium. 6 claims, 1 drawing figure
YehZYXW of Escherichia coli Is a Low-Affinity, Non-Osmoregulatory Betaine-Specific ABC Transporter.
Lang, Shenhui; Cressatti, Marisa; Mendoza, Kris E; Coumoundouros, Chelsea N; Plater, Samantha M; Culham, Doreen E; Kimber, Matthew S; Wood, Janet M
2015-09-22
Transporter-mediated osmolyte accumulation stimulates the growth of Escherichia coli in high-osmolality environments. YehZYXW was predicted to be an osmoregulatory transporter because (1) osmotic and stationary phase induction of yehZYXW is mediated by RpoS, (2) the Yeh proteins are homologous to the components of known osmoregulatory ABC transporters (e.g., ProU of E. coli), and (3) YehZ models based on the structures of periplasmic betaine-binding proteins suggested that YehZ retains key betaine-binding residues. The betaines choline-O-sulfate, glycine betaine, and dimethylsulfoniopropionate bound YehZ and ProX with millimolar and micromolar affinities, respectively, as determined by equilibrium dialysis and isothermal titration calorimetry. The crystal structure of the YehZ apoprotein, determined at 1.5 Å resolution (PDB ID: 4WEP ), confirmed its similarity to other betaine-binding proteins. Small and nonpolar residues in the hinge region of YehZ (e.g., Gly223) pack more closely than the corresponding residues in ProX, stabilizing the apoprotein. Betaines bound YehZ-Gly223Ser an order of magnitude more tightly than YehZ, suggesting that weak substrate binding in YehZ is at least partially due to apo state stabilization. Neither ProX nor YehZ bound proline. Assays based on osmoprotection or proline auxotrophy failed to detect YehZYXW-mediated uptake of proline, betaines, or other osmolytes. However, transport assays revealed low-affinity glycine betaine uptake, mediated by YehZYXW, that was inhibited at high salinity. Thus, YehZYXW is a betaine transporter that shares substrate specificity, but not an osmoregulatory function, with homologues like E. coli ProU. Other work suggests that yehZYXW may be an antivirulence locus whose expression promotes persistent, asymptomatic bacterial infection.
Energy Technology Data Exchange (ETDEWEB)
Lambeau, G.; Barhanin, J.; Schweitz, H.; Qar, J.; Lazdunski, M. (Centre de Biochimie, Nice (France))
1989-07-05
Four new monochain phospholipases were purified from the Oxyuranus scutellatus (taipan) venom. Three of them were highly toxic when injected into mice brain. One of these neurotoxic phospholipases, OS2, was iodinated and used in binding experiments to demonstrate the presence of two families of specific binding sites in rat brain synaptic membranes. The affinities were exceptionally high, Kd1 = 1.5 +/- 0.5 pM and Kd2 = 45 +/- 10 pM, and the maximal binding capacities were Bmax 1 = 1 +/- 0.4 and Bmax 2 = 3 +/- 0.5 pmol/mg of protein. Both binding sites were sensitive to proteolysis and demonstrated to be located on proteins of Mr 85,000-88,000 and 36,000-51,000 by cross-linking and photoaffinity labeling techniques. The binding of {sup 125}I-OS2 to synaptic membranes was dependent on Ca2+ ions and enhanced by Zn2+ ions which inhibit phospholipase activity. Competition experiments have shown that, except for beta-bungarotoxin, a number of known toxic snake or bee phospholipases have very high affinities for the newly identified binding sites. A good correlation (r = 0.80) was observed between toxicity and affinity but not between phospholipase activity and affinity.
Directory of Open Access Journals (Sweden)
A. Fallah Nosrat Abad
2015-06-01
Full Text Available The high cost of fertilizers in farming systems, soil pollution and degradation of soil are factors that caused to full use of available renewable nutrient sources of plant (organic and biological with optimal application of fertilizers in order to maintain fertility, structure, biological activity, exchange capacity and water-holding capacity of the water in soil. Therefore, in recent years, according to investigators biofertilizers and organic farming as an alternative to chemical fertilizers has been drawn. Through this study, we examined the effects of triple superphosphate, organic matters and phosphate solubilizing microorganisms on quantitative and qualitative yield of wheat and nutrient uptake. The experiment was carried out in the factorial based on randomized complete block design. The factors were: 1-phosphate solubilizing bacteria in three levels including control, Pseudomonas Putida and Bacillus Coagulans bacteria, 2- triple superphosphate in five levels of 0, 25%, 50%, 75% and 100% and 3-organic matter in 2 levels of 0 and 15 ton/ha in the soil with high phosphorous accessibility (13 mg/kg soil but lower than sufficient limit for plant 15 mg/kg soil. The results showed that the highest amount of yield has been recorded in Pseudomonas Putida bacteria treatment with organic matter and 25% phosphate fertilizer. As a result, at the conditions of this experiment phosphate solubilizing bacteria and organic matter significantly had higher yield than control and their combination with phosphate fertilizer had significant effect on reducing phosphate fertilizer use.
International Nuclear Information System (INIS)
Yao Qing; Zhao Zijuan; Feng Gu; Li Xiaolin; Chen Baodong
2000-01-01
Red clover were grown in three-compartment boxes, and were inoculated with VA mycorrhizal fungus, Glomus mosseae. External hyphae were separated from root system by 30 μm pore size membrane. Phosphorus fertilizer indirectly labelled with 32 P and five kind of phosphates were applied in the hyphae compartment, and the ability of external hyphae to mobilize the sparingly soluble phosphates were evaluated. the results showed that external hyphae mobilized and up took Ca 2 -P, Ca 8 -P, Al-P, Fe.P, but not Ca 10 -P. The phosphorus uptake by clover from phosphates and the contribution of phosphates to clover phosphorus nutrition were ranked as Ca 2 -P > Ca 8 -P, Al-P > Fe-P
Utilisation of phosphate by jute from jute growing soils
International Nuclear Information System (INIS)
Ray, P.K.; Suiha, A.K.
1974-01-01
The uptake and utilisation of phosphate from different jute growing soils of West Bengal viz., Humaipur (24-Parganas), Haripal (Hooghly), Panagarh (Burdwan) and the Jute Agricultural Research Institute, Barrackpore (24-Parganas) were studied in pot under fertilizer combination of NP, PK and NPK. The soils from 24-Parganas district behaved in a similar manner with respect to dry matter yield, fertilizer P uptake and per cent utilisation of added P. The P deficient between the two, Humaipur soil, showed comparatively higher P utilisation. Other two soils, Haripal and Panagarh, though of different origin behaved similarly, highest soil P has been contributed by the P rich soil (J.A.R.I.) to the crop, though it showed minimum P fixation. (author)
Structural insights into a high affinity nanobody:antigen complex by homology modelling.
Skottrup, Peter Durand
2017-09-01
Porphyromonas gingivalis is a major periodontitis-causing pathogens. P. gingivalis secrete a cysteine protease termed RgpB, which is specific for Arg-Xaa bonds in substrates. Recently, a nanobody-based assay was used to demonstrate that RgpB could represent a novel diagnostic target, thereby simplifying. P. gingivalis detection. The nanobody, VHH7, had a high binding affinity and was specific for RgpB, when tested towards the highly identical RgpA. In this study a homology model of VHH7 was build. The complementarity determining regions (CDR) comprising the paratope residues responsible for RgpB binding were identified and used as input to the docking. Furthermore, residues likely involved in the RgpB epitope was identified based upon RgpB:RgpA alignment and analysis of residue surface accessibility. CDR residues and putitative RgpB epitope residues were used as input to an information-driven flexible docking approach using the HADDOCK server. Analysis of the VHH7:RgpB model demonstrated that the epitope was found in the immunoglobulin-like domain and residue pairs located at the molecular paratope:epitope interface important for complex stability was identified. Collectively, the VHH7 homology model and VHH7:RgpB docking supplies knowledge of the residues involved in the high affinity interaction. This information could prove valuable in the design of an antibody-drug conjugate for specific RgpB targeting. Copyright © 2017 Elsevier Inc. All rights reserved.
Garcia-Junceda, E; Shen, G J; Sugai, T; Wong, C H
1995-07-01
Three DHAP-dependent aldolases, rhamnulose-1-phosphate aldolase (Rham-1PA), fuculose-1-phosphate aldolase (Fuc-1PA) and tagatose-1,6-diphosphate aldolase (TDPA) have been cloned and overexpressed in Escherichia coli using two different expression vectors: pTrcHis for the expression of Rham-1PA and Fuc-1PA and pRSET for the expression of TDPA. In each case the recombinant enzyme is synthesized as a fusion protein with a hexahistidine tag on the N-terminus. The three enzymes have been purified in only one step by chelation affinity chromatography. The effects of cultivation temperature and concentration of inducer have been studied in order to optimize the expression of the recombinant proteins and to avoid the formation of inclusion bodies.
Uranium adsorption on ferrihydrite - effects of phosphate and humic acid
International Nuclear Information System (INIS)
Payne, T.E.; Davis, J.A.; Waite, T.D.
1996-01-01
Uranium adsorption on ferrihydrite was studied as a function of pH in systems equilibrated with air, in the presence and absence of added phosphate and humic acid (HA). The objective was to determine the influence of PO 3- 4 and HA on uranium uptake. Below pH 7, the sorption of UO 2+ 2 typically increases with increasing pH (the 'low pH sorption edge'), with a sharp decrease in sorption above this pH value (the 'high pH edge'). The presence of ΣPO 3- 4 of 10 -4 mol/L moved the low pH edge to the left by approximately 0.8 pH units. The PO 3- 4 was strongly bound by the ferrihydrite surface, and the increased uptake of U was attributed to the formation of ternary surface complexes involving both UO 2+ 2 and PO 3- 4 . The addition of HA (9 mg/L) increased U uptake at pH values below 7, with little effect at higher pH values. The positions of the pH edges were also affected by the ionic strength and total U content. These experiments show that sorption interactions involving PO 3- 4 and HA must be considered in order to model the behavior of U in natural systems, in which these components are often present. (orig.)
Characterization of high affinity [3H]triazolam binding in rat brain
International Nuclear Information System (INIS)
Earle, M.; Concas, A.; Yamamura, H.I.
1986-01-01
The hypnotic Triazolam (TZ), a triazolo (1,4)-benzodiazepine, displays a short physiological half life and has been used for the treatment of insomnia related to anxiety states. Specific binding properties of this recently tritiated TZ were characterized. The authors major objectives were the direct measurement of the temperature dependence and the GABA effect on [ 3 H]TZ binding. Saturation studies showed a shift to lower affinity at 37 0 C (K/sub d/ = 0.25 +/- 0.01 nM at O 0 C; K/sub d/ = 1.46 +/- 0.03 nM at 37 0 C) while the B/sub max/ values remained unchanged (1003 +/- 37 fmoles/mg prot. at 0 0 C and 1001 +/- 43 fmoles/mg prot. at 37 0 C). Inhibition studies showed that [ 3 H]TZ binding displayed no GABA shift at 0 0 C(K/sub i/ 0.37 +/- 0.03 nM/- GABA and K/sub i/ = 0.55 +/- 0.13 nM/+GABA) but a nearly two-fold shift was apparent at 37 0 C (K/sub i/ = 2.92 +/- 0.2 nM/-GABA; K/sub i/ = 1.37 +/- 0.11 mM/+GABA). These results were also confirmed by saturation studies in the presence or absence of GABA showing a shift to higher affinity in the presence of GABA only at 37 0 C. In Ro 15-1788/[ 3 H]TZ competition experiments the presence of GABA did not affect the inhibitory potency of Ro 15-1788 on [ 3 H]TZ binding at both temperatures. In conclusion [ 3 H]TZ binding showed an extremely high affinity for benzodiazepine receptors. In contrast to reported literature, the findings suggest that TZ interacts with benzodiazepine receptors similar to other benzodiazepine agonists
Huang, Qingqing; Yu, Yao; Wan, Yanan; Wang, Qi; Luo, Zhang; Qiao, Yuhui; Su, Dechun; Li, Huafen
2018-06-01
A four-year field trial was conducted in a rice paddy in southern China to determine the effects of continuous phosphate fertilizer, pig manure, chicken manure, and sewage sludge application on soil Cd accumulation in soil and Cd uptake by rice. The results showed that continuous application of fertilizers with higher Cd levels caused Cd to accumulate and redistribute in various soil fractions. In turn, these effects influenced Cd bioavailability in rice plants. After four years of phosphate fertilizer, pig manure, chicken manure, and sewage sludge application, the annual soil Cd accumulation rates were 0.007-0.032 mg kg -1 , 0.005-0.022 mg kg -1 , 0.002-0.013 mg kg -1 , and 0.032-0.087 mg kg -1 , respectively. Relative to the control, the pig- and chicken manure treatments significantly increased soil pH and reduced DTPA-extractable Cd (DTPA-Cd) and the exchangeable Cd fraction (Exc-Cd). In contrast, sewage sludge application significantly increased DTPA-Cd and Cd in all soil fractions. Phosphate fertilization had no significant effect on soil pH, DTPA-Cd, or Exc-Cd. Pearson's correlation coefficients showed that the rice grain Cd levels varied directly with DTPA-Cd, and Exc-Cd but inversely with soil pH. Pig- or chicken manure decreased rice grain Cd content, but sewage sludge increased both soil Cd availability and rice grain Cd uptake. Application of phosphate fertilizer had no significant effect on rice grain Cd content. The continuous use of organic- or phosphate fertilizer with elevated Cd content at high application rates may induce soil Cd accumulation and influence rice grain Cd accumulation. Copyright © 2018 Elsevier Ltd. All rights reserved.
Marini, Cecilia; Ravera, Silvia; Buschiazzo, Ambra; Bianchi, Giovanna; Orengo, Anna Maria; Bruno, Silvia; Bottoni, Gianluca; Emionite, Laura; Pastorino, Fabio; Monteverde, Elena; Garaboldi, Lucia; Martella, Roberto; Salani, Barbara; Maggi, Davide; Ponzoni, Mirco; Fais, Franco; Raffaghello, Lizzia; Sambuceti, Gianmario
2016-01-01
Cancer metabolism is characterized by an accelerated glycolytic rate facing reduced activity of oxidative phosphorylation. This “Warburg effect” represents a standard to diagnose and monitor tumor aggressiveness with 18F-fluorodeoxyglucose whose uptake is currently regarded as an accurate index of total glucose consumption. Studying cancer metabolic response to respiratory chain inhibition by metformin, we repeatedly observed a reduction of tracer uptake facing a marked increase in glucose consumption. This puzzling discordance brought us to discover that 18F-fluorodeoxyglucose preferentially accumulates within endoplasmic reticulum by exploiting the catalytic function of hexose-6-phosphate-dehydrogenase. Silencing enzyme expression and activity decreased both tracer uptake and glucose consumption, caused severe energy depletion and decreased NADPH content without altering mitochondrial function. These data document the existence of an unknown glucose metabolism triggered by hexose-6-phosphate-dehydrogenase within endoplasmic reticulum of cancer cells. Besides its basic relevance, this finding can improve clinical cancer diagnosis and might represent potential target for therapy. PMID:27121192
Phosphorus deficiency enhances molybdenum uptake by tomato plants
International Nuclear Information System (INIS)
Heuwinkel, H.; Kirkby, E.A.; Le Bot, J.; Marschner, H.
1992-01-01
Water culture experiments are described which provide conclusive evidence that Mo uptake by tomato plants is markedly enhanced by P deficiency. In a longterm experiment, which ran for 11 days, in marked contrast to the uptake of other nutrients, a three fold higher Mo uptake rate was observed after only four days of withdrawal of P from the nutrient medium. In contrast to the gradual increase in pH of the nutrient medium of the plants supplied with P, the pH in the medium of the -P plants fell. Throughout the growth of these plants net H+ efflux could be accounted for by excess cation over anion uptake, indicating that organic acid extrusion plays no major role in the observed fall in pH. Further evidence that Mo uptake is enhanced in P deficient tomato plants is provided in short-term nutrient solution experiments (1h and 4h) using radioactive molybdenum (99Mo). Compared with P sufficient plants, the uptake rates of 99Mo by P deficient plants were three to five times higher after 1h and nine to twelve times higher after 4h. Resupplying P during the uptake periods to deficient plants reduced the uptake rate of 99Mo to values similar to those of P sufficient plants. It is concluded that the uptake of molybdate occurs via phosphate binding/ transporting sites at the plasma membrane of root cells. Further support for this conclusion comes from exchange experiments with non-labelled molybdenum, which show a much larger amount of 99Mo exchangeable from the roots of P deficient plants
Ayub, J. Juri; Valverde, L. Rubio; Garcia-Sanchez, M. J.; Fernandez, J. A.; Velasco, R. H.
2008-08-01
Caesium uptake by plant roots has been normally associated with the uptake of potassium as the potassium transport systems present in plants have also the capacity to transport caesium. Three grass species (Eragrostis curvula, Cynodon sp and Distichlis spicata) growing in seminatural grassland of central Argentina were selected to study their capability to incorporate Cs+ (and K+) using electrophysiological techniques. Although the 137Cs soil inventory ranged between 328-730 Bq m-2 in this region, no 137Cs activity was detected in these plants. However, all the species, submitted previously to K+ starvation, showed the uptake of both Cs+ and K+ when micromolar concentrations of these cations were present in the medium. The uptake showed saturation kinetics for both cations that could be fitted to the Michelis-Menten model. KM values were smaller for K+ than for Cs+, indicating a higher affinity for the first cation. The presence of increasing K+ concentrations in the assay medium inhibited Cs+ uptake in Cynodon sp., as expected if both cations are transported by the same transport systems. This effect is due to the competition of both ions for the union sites of the high affinity potassium transporters. In field situation, where soil concentration of Cs+ is smaller than K+ concentration, is then expectable that caesium activity in plants is not detectable. Nevertheless, the studied plants would have the capacity to incorporate caesium if its availability in soil solution increases. In addition, studies of Cs/K interaction can help us to understand the variability in transfer factors.
International Nuclear Information System (INIS)
Ayub, J. Juri; Velasco, R. H.; Valverde, L. Rubio; Garcia-Sanchez, M. J.; Fernandez, J. A.
2008-01-01
Caesium uptake by plant roots has been normally associated with the uptake of potassium as the potassium transport systems present in plants have also the capacity to transport caesium. Three grass species (Eragrostis curvula, Cynodon sp and Distichlis spicata) growing in seminatural grassland of central Argentina were selected to study their capability to incorporate Cs + (and K + ) using electrophysiological techniques. Although the 137 Cs soil inventory ranged between 328-730 Bq m -2 in this region, no 137 Cs activity was detected in these plants. However, all the species, submitted previously to K + starvation, showed the uptake of both Cs + and K + when micromolar concentrations of these cations were present in the medium. The uptake showed saturation kinetics for both cations that could be fitted to the Michelis-Menten model. K M values were smaller for K + than for Cs + , indicating a higher affinity for the first cation. The presence of increasing K + concentrations in the assay medium inhibited Cs + uptake in Cynodon sp., as expected if both cations are transported by the same transport systems. This effect is due to the competition of both ions for the union sites of the high affinity potassium transporters. In field situation, where soil concentration of Cs + is smaller than K + concentration, is then expectable that caesium activity in plants is not detectable. Nevertheless, the studied plants would have the capacity to incorporate caesium if its availability in soil solution increases. In addition, studies of Cs/K interaction can help us to understand the variability in transfer factors
Energy Technology Data Exchange (ETDEWEB)
Sato, Atsushi, E-mail: asatou@ari.pref.niigata.jp [Niigata Horticultural Research Center, 177 Mano, Seiro, Niigata 957-0111 (Japan); Takeda, Hiroyuki [Niigata Horticultural Research Center, 177 Mano, Seiro, Niigata 957-0111 (Japan); Oyanagi, Wataru [Niigata Livestock Research Center, 178 Tanahire, Sanjo, Niigata 955-0143 (Japan); Nishihara, Eiji [Tottori University, 4-101 Koyama-Minami, Tottori 680-8550 (Japan); Murakami, Masaharu [Soil Environment Division, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305-8604 (Japan)
2010-09-15
A field experiment was conducted to evaluate the efficacy of animal waste compost (AWC) in reducing Cd uptake by spinach (Spinacia oleracea L.). Spinach was grown in a field that had been treated by having cattle, swine, or poultry waste compost incorporated into the soil before each crop throughout 4 years of rotational vegetable production. Cadmium concentration was 34-38% lower in spinach harvested from the AWC-treated soils than in the chemical fertilizer-treated soil. Although the repeated application of swine and poultry compost caused significant P accumulation in the cropped soils, that of cattle compost did not. These results indicate that cattle compost with high affinity for Cd and low P content should be the preferred soil amendment when used to reduce Cd uptake by spinach.
International Nuclear Information System (INIS)
Sato, Atsushi; Takeda, Hiroyuki; Oyanagi, Wataru; Nishihara, Eiji; Murakami, Masaharu
2010-01-01
A field experiment was conducted to evaluate the efficacy of animal waste compost (AWC) in reducing Cd uptake by spinach (Spinacia oleracea L.). Spinach was grown in a field that had been treated by having cattle, swine, or poultry waste compost incorporated into the soil before each crop throughout 4 years of rotational vegetable production. Cadmium concentration was 34-38% lower in spinach harvested from the AWC-treated soils than in the chemical fertilizer-treated soil. Although the repeated application of swine and poultry compost caused significant P accumulation in the cropped soils, that of cattle compost did not. These results indicate that cattle compost with high affinity for Cd and low P content should be the preferred soil amendment when used to reduce Cd uptake by spinach.
Energy Technology Data Exchange (ETDEWEB)
Zong, Enmin [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou 318000 (China); Liu, Xiaohuan, E-mail: liuxiaohuancaf@163.com [School of Engineering, National Engineering and Technology Research Center of Wood-Based Resources Comprehensive Utilization, and Key Laboratory of Wood Science and Technology of Zhejiang Province, Zhejiang Agriculture and Forestry University, Hangzhou, Lin’an 311300 (China); Jiang, Jinhua [Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou 318000 (China); Fu, Shenyuan [School of Engineering, National Engineering and Technology Research Center of Wood-Based Resources Comprehensive Utilization, and Key Laboratory of Wood Science and Technology of Zhejiang Province, Zhejiang Agriculture and Forestry University, Hangzhou, Lin’an 311300 (China); Chu, Fuxiang [Institute of Chemical Industry of Forestry Products, CAF, Nanjing 210037 (China)
2016-11-30
Highlights: • LBR-Zr was evaluated as a novel biosorbent for phosphate removal. • Effects of process factors on phosphate adsorption were studied in detail. • LBR-Zr showed markedly enhanced phosphate adsorption compared to LBR. • The underlying mechanism for phosphate adsorption of LBR-Zr was fully investigated. - Abstract: Zirconium(IV) loaded lignocellulosic butanol residue (LBR-Zr) used for the adsorption of phosphate (P) ions from aqueous solution was synthesized and evaluated. The adsorption isotherms were fitted well with the Freundlich and Temkin modes. Thermodynamic analyses indicated that phosphate adsorption on the LBR-Zr increased with increasing temperature from 298 to 338 K. The kinetic datas were described better by the pseudo-second-order adsorption kinetic rate model. Increasing pH suppressed phosphate adsorption. Coexisting anions study exhibited that the incorporation of CO{sub 3}{sup 2−} anion had the largest influence on the phosphate adsorption capacity. The mechanism of adsorption process on LBR-Zr was analyzed by FTIR (Fourier transform infrared spectroscopy), scanning electron microscope (SEM) with an EDX (energy dispersive X-ray) and X-ray photoelectron spectroscopy (XPS) technologies, respectively. The above results confirmed that surface hydroxyl groups on biosorbent LBR-Zr were replaced by phosphate. The LBR-Zr with good specific affinity towards phosphate was a promising biosorbent for phosphate removal from aqueous solution. The research would be beneficial for developing a promising, eco-friendly phosphate biosorbent from plentiful lignocellulosic butanol residue.
International Nuclear Information System (INIS)
Francis, M.D.; Ferguson, D.L.; Tofe, A.J.; Bevan, J.A.; Michaels, S.E.
1980-01-01
We have investigated the in vitro adsorption of three C-14-labeled diphosphonates on calcium phosphate. The three are 1-hydroxy[1- 14 C]ethylidene diphosphonate (C-14 HEDP), [ 14 C]methylenediphosphonate (C-14 MDP), and hydroxy[ 14 C]-methylenediphosphonate (C-14 HMDP). All three adsorbed significantly more, per mole of calcium, on amorphous calcium phosphate than on crystalline hydroxyapatite. Among the three diphosphonates, C-14 HMDP adsorbed-on both amorphous and crystalline calcium phosphate-to a greater degree than did the other two bone-seeking agents. Moreover, when HMDP was complexed with Sn(II) and Tc-99m, it produced a significantly higher uptake of Tc-99m, per mg of calcium, in an isolated in vivo site of osteogenesis. The mechanisms of adsorption are discussed relative to the hydroxyl group on the diphosphonate, to the solubility of the calcium salts of the diphosphonates, and to the form of the calcium phosphate. These studies form a working rationale for the clinically observed high contrast obtained with Tc-99m HMDP between normal bone and soft tissue, and between normal and abnormal bone
Directory of Open Access Journals (Sweden)
McKee Karen L
2010-02-01
Full Text Available Abstract Background Cattail (Typha domingensis has been spreading in phosphorus (P enriched areas of the oligotrophic Florida Everglades at the expense of sawgrass (Cladium mariscus spp. jamaicense. Abundant evidence in the literature explains how the opportunistic features of Typha might lead to a complete dominance in P-enriched areas. Less clear is how Typha can grow and acquire P at extremely low P levels, which prevail in the unimpacted areas of the Everglades. Results Apparent P uptake kinetics were measured for intact plants of Cladium and Typha acclimated to low and high P at two levels of oxygen in hydroponic culture. The saturated rate of P uptake was higher in Typha than in Cladium and higher in low-P acclimated plants than in high-P acclimated plants. The affinity for P uptake was two-fold higher in Typha than in Cladium, and two- to three-fold higher for low-P acclimated plants compared to high-P acclimated plants. As Cladium had a greater proportion of its biomass allocated to roots, the overall uptake capacity of the two species at high P did not differ. At low P availability, Typha increased biomass allocation to roots more than Cladium. Both species also adjusted their P uptake kinetics, but Typha more so than Cladium. The adjustment of the P uptake system and increased biomass allocation to roots resulted in a five-fold higher uptake per plant for Cladium and a ten-fold higher uptake for Typha. Conclusions Both Cladium and Typha adjust P uptake kinetics in relation to plant demand when P availability is high. When P concentrations are low, however, Typha adjusts P uptake kinetics and also increases allocation to roots more so than Cladium, thereby improving both efficiency and capacity of P uptake. Cladium has less need to adjust P uptake kinetics because it is already efficient at acquiring P from peat soils (e.g., through secretion of phosphatases, symbiosis with arbuscular mycorrhizal fungi, nutrient conservation growth
Ando, A; Hisada, K; Ando, I
1977-10-01
The distribution of many inorganic compounds in rats was investigated in order to evaluate kidney affinity of inorganic compounds. In these experiments, 30%, 10-20% and 4-10% of administered dose was localized in the kidneys in 203Hg-acetate and 203 Bi-acetate, in H198AuCl4, 103PdCl2, 201TlCl, 210Pd(NO3)2 and H2(127M)TeO3, and in Na2(51)CrO4, 54MnCl2, (114m)InCl3 and 7BeCl2, respectively. Some bipositive ions and anions was hardly taken up into the kidneys. And in many hard acids according to classification of Lewis acids, the uptake rate into the kidneys was usually small. On the other hand, Hg, Au and Bi, which have strong binding power to the protein, showed high uptake rate in the kidneys. As Hg++, Au+ and Bi+++ was soft acids according to classification of Lewis acids, it was thought that these elements would bind strongly to soft base (RSH, RS-) present in the kidney.
The influence of different hydroponic conditions on thorium uptake by Brassica juncea var. foliosa.
Wang, Dingna; Zhou, Sai; Liu, Li; Du, Liang; Wang, Jianmei; Huang, Zhenling; Ma, Lijian; Ding, Songdong; Zhang, Dong; Wang, Ruibing; Jin, Yongdong; Xia, Chuanqin
2015-05-01
The effects of different hydroponic conditions (such as concentration of thorium (Th), pH, carbonate, phosphate, organic acids, and cations) on thorium uptake by Brassica juncea var. foliosa were evaluated. The results showed that acidic cultivation solutions enhanced thorium accumulation in the plants. Phosphate and carbonate inhibited thorium accumulation in plants, possibly due to the formation of Th(HPO4)(2+), Th(HPO4)2, or Th(OH)3CO3 (-) with Th(4+), which was disadvantageous for thorium uptake in the plants. Organic aids (citric acid, oxalic acid, lactic acid) inhibited thorium accumulation in roots and increased thorium content in the shoots, which suggested that the thorium-organic complexes did not remain in the roots and were beneficial for thorium transfer from the roots to the shoots. Among three cations (such as calcium ion (Ca(2+)), ferrous ion (Fe(2+)), and zinc ion (Zn(2+))) in hydroponic media, Zn(2+) had no significant influence on thorium accumulation in the roots, Fe(2+) inhibited thorium accumulation in the roots, and Ca(2+) was found to facilitate thorium accumulation in the roots to a certain extent. This research will help to further understand the mechanism of thorium uptake in plants.
Wang, Xin-Xin; Hoffland, Ellis; Feng, Gu; Kuyper, Thomas W
2017-01-01
Phytate is the most abundant form of soil organic phosphorus (P). Increased P nutrition of arbuscular mycorrhizal plants derived from phytate has been repeatedly reported. Earlier studies assessed acid phosphatase rather than phytase as an indication of mycorrhizal fungi-mediated phytate use. We investigated the effect of mycorrhizal hyphae-mediated phytase activity on P uptake by maize. Two maize ( Zea mays L.) cultivars, non-inoculated or inoculated with the arbuscular mycorrhizal fungi Funneliformis mosseae or Claroideoglomus etunicatum , were grown for 45 days in two-compartment rhizoboxes, containing a root compartment and a hyphal compartment. The soil in the hyphal compartment was supplemented with 20, 100, and 200 mg P kg -1 soil as calcium phytate. We measured activity of phytase and acid phosphatase in the hyphal compartment, hyphal length density, P uptake, and plant biomass. Our results showed: (1) phytate addition increased phytase and acid phosphatase activity, and resulted in larger P uptake and plant biomass; (2) increases in P uptake and biomass were correlated with phytase activity but not with acid phosphatase activity; (3) lower phytate addition rate increased, but higher addition rate decreased hyphal length density. We conclude that P from phytate can be taken up by arbuscular mycorrhizal plants and that phytase plays a more important role in mineralizing phytate than acid phosphatase.
Energy Technology Data Exchange (ETDEWEB)
Wang, Zhe; Xing, Mingchao; Fang, Wenkan; Wu, Deyi, E-mail: dywu@sjtu.edu.cn
2016-03-15
Graphical abstract: - Highlights: • Magnetite core/zirconia shell nanocomposite was prepared by one-step method. • Fe/Zr molar ratio of 4/1 allowed high magnetization and high adsorption capacity. • The nanocomposite had good selectivity towards phosphate. • Ligand exchange was the adsorption mechanism of phosphate. • Desorption of adsorbed phosphate could be achieved by NaOH treatment. - Abstract: A self-assembled magnetite core/zirconia shell (Fe{sub 3}O{sub 4}@ZrO{sub 2}) nanoparticle material was fabricated by the one-step co-precipitation method to capture phosphate from water. Fe{sub 3}O{sub 4}@ZrO{sub 2} with different Fe/Zr molar ratios were obtained and characterized by XRD, TEM, BET surface area and magnetization. It was shown that, with the decreasing of Fe/Zr molar ratio, magnetization decreased whereas surface area and adsorption capacity of phosphate increased. Fe{sub 3}O{sub 4}@ZrO{sub 2} with the ratio of higher than 4:1 had satisfactory magnetization property (>23.65 emu/g), enabling rapid magnetic separation from water and recycle of the spent adsorbent. The Langmuir adsorption capacity of Fe{sub 3}O{sub 4}@ZrO{sub 2} reached 27.93–69.44 mg/g, and the adsorption was fast (90% of phosphate removal within 20 min). The adsorption decreases with increasing pH, and higher ionic strength caused slight increase in adsorption at pH > about 5.5. The presence of chloride, nitrate and sulfate anions did not bring about significant changes in adsorption. As a result, Fe{sub 3}O{sub 4}@ZrO{sub 2} performed well to remove phosphate from real wastewater. These results were interpreted by the ligand exchange mechanism, i.e., the direct coordination of phosphate onto zirconium by replacement of hydroxyl groups. Results suggested that phosphate reacted mainly with surface hydroxyl groups but diffusion into interior of zirconia phase also contributed to adsorption. The adsorbed phosphate could be desorbed with a NaOH treatment and the regenerated Fe
Zhang, Zhuo; Ren, Jie; Wang, Mei; Song, Xinlai; Zhang, Chao; Chen, Jiayu; Li, Fasheng; Guo, Guanlin
2016-09-01
Chemical immobilization by phosphates has been widely and successfully applied to treat Pb in wastewater and contaminated soils. Pb in wastewaters and soils, however, always coexists with other heavy metals and their competitive reactions with phosphates have not been quantitatively and systematically studied. In this approach, immobilization of Pb, Zn, and Cd by mono-, di-, and tripotassium phosphate (KH2PO4, K2HPO4, and K3PO4) was observed in the single- and ternary-metals solutions. The immobilization rates of the three metals were determined by the residual concentration. The mineral composition and structure of the precipitates were characterized by powder X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The results indicated that competitive reaction occurred in Pb-Zn-Cd ternary system, with immobilization rates decrease of system. The reaction of Pb with three phosphates exhibited intense competitiveness and the phosphates had a stronger affinity for Pb when Cl(-) was added. Pb-phosphate minerals formed by KH2PO4 with the better crystalline characteristics and largest size were very stable with a low dissolution rate (system. Copyright © 2016 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Brian H. Carrick
2016-03-01
Full Text Available Isolation of endogenous proteins from Saccharomyces cerevisiae has been facilitated by inserting encoding polypeptide affinity tags at the C-termini of chromosomal open reading frames (ORFs using homologous recombination of DNA fragments. Tagged protein isolation is limited by a number of factors, including high cost of affinity resins for bulk isolation and low concentration of ligands on the resin surface, leading to low isolation efficiencies and trapping of contaminants. To address this, we have created a recombinant “CelTag” DNA construct from which PCR fragments can be created to easily tag C-termini of S. cerevisiae ORFs using selection for a nat1 marker. The tag has a C-terminal cellulose binding module to be used in the first affinity step. Microgranular cellulose is very inexpensive and has an effectively continuous ligand on its surface, allowing rapid, highly efficient purification with minimal background. Cellulose-bound proteins are released by specific cleavage of an included site for TEV protease, giving nearly pure product. The tag can be lifted from the recombinant DNA construct either with or without a 13x myc epitope tag between the target ORF and the TEV protease site. Binding of CelTag protein fusions to cellulose is stable to high salt, nonionic detergents, and 1 M urea, allowing stringent washing conditions to remove loosely associated components, as needed, before specific elution. It is anticipated that this reagent could allow isolation of protein complexes from large quantities of yeast extract, including soluble, membrane-bound, or nucleic acid-associated assemblies.
Tsvetkova, Yoanna; Beztsinna, Nataliia; Jayapaul, Jabadurai; Weiler, Marek; Arns, Susanne; Shi, Yang; Lammers, Twan; Kiessling, Fabian
2016-01-01
Flavin mononucleotide (FMN) is a riboflavin derivative that can be exploited to target the riboflavin transporters (RFTs) and the riboflavin carrier protein (RCP) in cells with high metabolic activity. In this study we present the synthesis of different FMN-coated ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) and their efficiency as targeting contrast agents. Since FMN alone cannot stabilize the nanoparticles, we used adenosine phosphates--AMP, ADP and ATP--as spacers to obtain colloidally stable nanoparticles. Nucleotides with di- and triphosphate groups were intended to increase the USPIO charge and thus improve zeta potential and stability. However, all nanoparticles formed negatively charged clusters with similar properties in terms of zeta potential (-28 ± 2 mV), relaxivity (228-259 mM(-1) s(-1) at 3 T) and hydrodynamic radius (53-85 nm). Molecules with a higher number of phosphate groups, such as ADP and ATP, have a higher adsorption affinity towards iron oxide, which, instead of providing more charge, led to partial desorption and replacement of FMN. Hence, we obtained USPIOs carrying different amounts of targeting agent, which significantly influenced the nanoparticles' uptake. The nanoparticles' uptake by different cancer cells and HUVECs was evaluated photometrically and with MR relaxometry, showing that the cellular uptake of the USPIOs increases with the FMN amount on their surface. Thus, for USPIOs targeted with riboflavin derivatives the use of spacers with increasing numbers of phosphate groups does not improve either zeta potential or the particles' stability, but rather detaches the targeting moieties from their surface, leading to lower cellular uptake. Copyright © 2015 John Wiley & Sons, Ltd.
Yagi, Shintaro; Fukushi, Keisuke
2012-10-15
The sorption behavior and mechanism of phosphate on monohydrocalcite (CaCO(3)·H(2)O: MHC) were examined using batch sorption experiments as a function of phosphate concentrations, ionic strengths, temperatures, and reaction times. The mode of PO(4) sorption is divisible into three processes depending on the phosphate loading. At low phosphate concentrations, phosphate is removed by coprecipitation of phosphate during the transformation of MHC to calcite. The sorption mode at the low-to-moderate phosphate concentrations is most likely an adsorption process because the sorption isotherm at the conditions can be fitted reasonably with the Langmuir equation. The rapid sorption kinetics at the conditions is also consistent with the adsorption reaction. The adsorption of phosphate on MHC depends strongly on ionic strength, but slightly on temperature. The maximum adsorption capacities of MHC obtained from the regression of the experimental data to the Langmuir equation are higher than those reported for stable calcium carbonate (calcite or aragonite) in any conditions. At high phosphate concentrations, the amount of sorption deviates from the Langmuir isotherm, which can fit the low-to-moderate phosphate concentrations. Speciation-saturation analyses of the reacted solutions at the conditions indicated that the solution compositions which deviate from the Langmuir equation are supersaturated with respect to a certain calcium phosphate. The obtained calcium phosphate is most likely amorphous calcium phosphate (Ca(3)(PO(4))(2)·xH(2)O). The formation of the calcium phosphate depends strongly on ionic strength, temperature, and reaction times. The solubility of MHC is higher than calcite and aragonite because of its metastability. Therefore, the higher solubility of MHC facilitates the formation of the calcium phosphates more than with calcite and aragonite. Copyright © 2012 Elsevier Inc. All rights reserved.
International Nuclear Information System (INIS)
Neto, Carina; Oliveira, Maria Cristina; Gano, Lurdes; Marques, Fernanda; Santos, Isabel; Morais, Goreti Ribeiro; Yasuda, Takumi; Thiemann, Thies; Botelho, Filomena; Oliveira, Carlos F.
2009-01-01
Three novel 17α-ethynyl-Δ 6,7 -estra-3,17β-diols and their 17α-[ 125 I]-iodovinyl derivatives, containing different C7-cyanoalkyl chains, were studied as potential radioligands for the estrogen receptor. The influence of the chain length on the biological behaviour of the compounds was assessed through in vitro ER binding assays of the ethynyl derivatives and breast cancer cell uptake studies of the 17α-[ 125 I]-iodovinyl-Δ 6,7 -estra-3,17β-diols. A difference in alkyl chain induced a decrease in ER binding affinities of substances, however, the receptor-binding affinities (RBA) of all compounds were lower than that of estradiol itself. In addition, a non-specific cell binding was observed which is in accordance with the encountered ethynyl RBA values suggesting that the uptake is not ER mediated
Lécuyer, Christophe; Fourel, François; Martineau, François; Amiot, Romain; Bernard, Aurélien; Daux, Valérie; Escarguel, Gilles; Morrison, John
2007-01-01
A high-precision, and rapid on-line method for oxygen isotope analysis of silver phosphate is presented. The technique uses high-temperature elemental analyzer (EA)-pyrolysis interfaced in continuous flow (CF) mode to an isotopic ratio mass spectrometer (IRMS). Calibration curves were generated by synthesizing silver phosphate with a 13 per thousand spread in delta(18)O values. Calibration materials were obtained by reacting dissolved potassium dihydrogen phosphate (KH(2)PO(4)) with water samples of various oxygen isotope compositions at 373 K. Validity of the method was tested by comparing the on-line results with those obtained by classical off-line sample preparation and dual inlet isotope measurement. In addition, silver phosphate precipitates were prepared from a collection of biogenic apatites with known delta(18)O values ranging from 12.8 to 29.9 per thousand (V-SMOW). Reproducibility of +/- 0.2 per thousand was obtained by the EA-Py-CF-IRMS method for sample sizes in the range 400-500 microg. Both natural and synthetic samples are remarkably well correlated with conventional (18)O/(16)O determinations. Silver phosphate is a very stable material and easy to degas and, thus, could be considered as a good candidate to become a reference material for the determination of (18)O/(16)O ratios of phosphate by high-temperature pyrolysis. Copyright 2006 John Wiley & Sons, Ltd.
Zirconium phosphate nanoplatelets: a biocompatible nanomaterial for drug delivery to cancer
Saxena, Vipin; Diaz, Agustin; Clearfield, Abraham; Batteas, James D.; Hussain, Muhammad Delwar
2013-02-01
The objective of this study was to evaluate the biocompatibility of zirconium phosphate (ZrP) nanoplatelets (NPs), and their use in drug delivery. ZrP and doxorubicin-intercalated ZrP (DOX:ZrP) NPs were characterized by using X-Ray Powder Diffraction (XRPD), Thermogravimetric Analysis (TGA), Transmission Electron Micrography (TEM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Biocompatibility of ZrP NPs was evaluated in human embryonic kidney (HEK-293), breast cancer (MCF-7), metastatic breast cancer (MDA-MB-231), ovarian cancer (OVCAR-3), resistant cancer (NCI-RES/ADR) cells and mouse macrophage (RAW 264.7) cell lines. Hemocompatibility of ZrP NPs was evaluated with human red blood cells. Simulated body fluid (SBF) of pH 7.4 was used to determine the in vitro release of doxorubicin from DOX:ZrP NPs. Cellular uptake and in vitro cytotoxicity studies of DOX:ZrP NPs were determined in MDA-MB-231. The ZrP nanomaterial can be prepared in the 100-200 nm size range with a platelet-like shape. The ZrP NPs themselves are biocompatible, hemocompatible and showed no toxicity to the macrophage cells. ZrP NPs can intercalate high loads (35% w/w) of doxorubicin between their layers. The release of DOX was sustained for about 2 weeks. DOX:ZrP NPs showed higher cellular uptake and increased cytotoxicity than free DOX in MDA-MB-231 cells. ZrP NPs are highly biocompatible, can intercalate large amounts of drugs and sustain the release of drugs. ZrP NPs improved the cellular uptake and cytotoxicity of DOX to MDA-MB-231 cells. ZrP NPs are promising nanocarriers for drug delivery in cancer therapy.The objective of this study was to evaluate the biocompatibility of zirconium phosphate (ZrP) nanoplatelets (NPs), and their use in drug delivery. ZrP and doxorubicin-intercalated ZrP (DOX:ZrP) NPs were characterized by using X-Ray Powder Diffraction (XRPD), Thermogravimetric Analysis (TGA), Transmission Electron Micrography (TEM), Scanning Electron Microscopy (SEM
Energy Technology Data Exchange (ETDEWEB)
Hall, Justin; Brault, Amy; Vincent, Fabien; Weng, Shawn; Wang, Hong; Dumlao, Darren; Aulabaugh, Ann; Aivazian, Dikran; Castro, Dana; Chen, Ming; Culp, Jeffrey; Dower, Ken; Gardner, Joseph; Hawrylik, Steven; Golenbock, Douglas; Hepworth, David; Horn, Mark; Jones, Lyn; Jones, Peter; Latz, Eicke; Li, Jing; Lin, Lih-Ling; Lin, Wen; Lin, David; Lovering, Frank; Niljanskul, Nootaree; Nistler, Ryan; Pierce, Betsy; Plotnikova, Olga; Schmitt, Daniel; Shanker, Suman; Smith, James; Snyder, William; Subashi, Timothy; Trujillo, John; Tyminski, Edyta; Wang, Guoxing; Wong, Jimson; Lefker, Bruce; Dakin, Leslie; Leach, Karen (UMASS, MED); (Pfizer)
2017-09-21
Cyclic GMP-AMP synthase (cGAS) initiates the innate immune system in response to cytosolic dsDNA. After binding and activation from dsDNA, cGAS uses ATP and GTP to synthesize 2', 3' -cGAMP (cGAMP), a cyclic dinucleotide second messenger with mixed 2'-5' and 3'-5' phosphodiester bonds. Inappropriate stimulation of cGAS has been implicated in autoimmune disease such as systemic lupus erythematosus, thus inhibition of cGAS may be of therapeutic benefit in some diseases; however, the size and polarity of the cGAS active site makes it a challenging target for the development of conventional substrate-competitive inhibitors. We report here the development of a high affinity (KD = 200 nM) inhibitor from a low affinity fragment hit with supporting biochemical and structural data showing these molecules bind to the cGAS active site. We also report a new high throughput cGAS fluorescence polarization (FP)-based assay to enable the rapid identification and optimization of cGAS inhibitors. This FP assay uses Cy5-labelled cGAMP in combination with a novel high affinity monoclonal antibody that specifically recognizes cGAMP with no cross reactivity to cAMP, cGMP, ATP, or GTP. Given its role in the innate immune response, cGAS is a promising therapeutic target for autoinflammatory disease. Our results demonstrate its druggability, provide a high affinity tool compound, and establish a high throughput assay for the identification of next generation cGAS inhibitors.
International Nuclear Information System (INIS)
Miles, L.A.; Plow, E.F.
1986-01-01
An antibody population that reacted with the high-affinity lysine binding site of human plasminogen was elicited by immunizing rabbits with an elastase degradation product containing kringles 1-3 (EDP I). This antibody was immunopurified by affinity chromatography on plasminogen-Sepharose and elution with 0.2 M 6-aminohexanoic acid. The eluted antibodies bound [ 125 I]EDP I, [ 125 I]Glu-plasminogen, and [ 125 I]Lys-plasminogen in radioimmunoassays, and binding of each ligand was at least 99% inhibited by 0.2 M 6-aminohexanoic acid. The concentrations for 50% inhibition of [ 125 I]EDP I binding by tranexamic acid, 6-aminohexanoic acid, and lysine were 2.6, 46, and l730 μM, respectively. Similar values were obtained with plasminogen and suggested that an unoccupied high-affinity lysine binding site was required for antibody recognition. The antiserum reacted exclusively with plasminogen derivatives containing the EDP I region and did not react with those lacking an EDP I region, or with tissue plasminogen activator or prothrombin, which also contains kringles. By immunoblotting analyses, a chymotryptic degradation product of M/sub r/ 20,000 was derived from EDP I that retained reactivity with the antibody. α 2 -Antiplasmin inhibited the binding of radiolabeled EDP I, Glu-plasminogen, or Lys-plasminogen by the antiserum, suggesting that the recognized site is involved in the noncovalent interaction of the inhibitor with plasminogen. The binding of [ 125 I]EDP I to fibrin was also inhibited by the antiserum. The observations provide independent evidence for the role of the high-affinity lysine binding site in the functional interactions of plasminogen with its primary substrate and inhibitor
International Nuclear Information System (INIS)
Nikiforova, A.; Kinova, L.; Peneva, C.; Taskaeva, I.; Petrova, P.
2005-01-01
We use the approach described by Westinghouse Savannah River Company using ammonium molybdophosphate (AMP) to remove elevated concentrations of radioactive cesium to facilitate handling waste samples from NPP K ozloduy . Preliminary series of tests were carried out to determine the exact conditions for sufficient cesium removal from five simulated waste solutions with concentrations of compounds, whose complexing power complicates any subsequent processing. Simulated wastes solutions contain high concentrations of nitrates, borates, H 2 C 2 O 4 , ethylenediaminetetraacetate (EDTA) and Citric acid, according to the composition of the real waste from the NPP. On this basis a laboratory treatment protocol was created. This experiment is a preparation for the analysis of real waste samples. In this sense the results are preliminary. Unwanted removal of non-cesium radioactive species from simulated waste solutions was studied with gamma spectrometry with the aim to find a compromise between on the one hand the AMP effectiveness and on the other hand unwanted affinity to AMP of Uranium and Americium. Success for the treatment protocol is defined by proving minimal uptake of U and Am, while at the same time demonstrating good removal effectiveness through the use of AMP. Uptake of U and Am were determined as influenced by oxidizing agents at nitric acid concentrations, proposed by Savannah River National laboratory. It was found that AMP does not significantly remove U and Am when concentration of oxidizing agents is more than 0.1M for simulated waste solutions and for contact times inherent in laboratory treatment protocol. Uranium and Americium affinity under experimental conditions for cesium removal were evaluated from gamma spectrometric data. Results are given for the model experiment and an approach for the real waste analysis is chosen. Under our experimental conditions simulated wastes solutions showed minimal affinity to AMP when U and Am are most probably in
14-O-Methylmorphine: A Novel Selective Mu-Opioid Receptor Agonist with High Efficacy and Affinity.
Zádor, Ferenc; Balogh, Mihály; Váradi, András; Zádori, Zoltán S; Király, Kornél; Szűcs, Edina; Varga, Bence; Lázár, Bernadette; Hosztafi, Sándor; Riba, Pál; Benyhe, Sándor; Fürst, Susanna; Al-Khrasani, Mahmoud
2017-11-05
14-O-methyl (14-O-Me) group in morphine-6-O-sulfate (M6SU) or oxymorphone has been reported to be essential for enhanced affinity, potency and antinociceptive effect of these opioids. Herein we report on the pharmacological properties (potency, affinity and efficacy) of the new compound, 14-O-methylmorphine (14-O-MeM) in in vitro. Additionally, we also investigated the antinociceptive effect of the novel compound, as well as its inhibitory action on gastrointestinal transit in in vivo. The potency and efficacy of test compound were measured by [ 35 S]GTPγS binding, isolated mouse vas deferens (MVD) and rat vas deferens (RVD) assays. The affinity of 14-O-MeM for opioid receptors was assessed by radioligand binding and MVD assays. The antinociceptive and gastrointestinal effects of the novel compound were evaluated in the rat tail-flick test and charcoal meal test, respectively. Morphine, DAMGO, Ile 5,6 deltorphin II, deltorphin II and U-69593 were used as reference compounds. 14-O-MeM showed higher efficacy (E max ) and potency (EC 50 ) than morphine in MVD, RVD or [ 35 S]GTPγS binding. In addition, 14-O-MeM compared to morphine showed higher affinity for μ-opioid receptor (MOR). In vivo, in rat tail-flick test 14-O-MeM proved to be stronger antinociceptive agent than morphine after peripheral or central administration. Additionally, both compounds inhibited the gastrointestinal peristalsis. However, when the antinociceptive and antitransit doses for each test compound are compared, 14-O-MeM proved to have slightly more favorable pharmacological profile. Our results affirm that 14-O-MeM, an opioid of high efficacy and affinity for MOR can be considered as a novel analgesic agent of potential clinical value. Copyright © 2017 Elsevier B.V. All rights reserved.
Uptake and disposition of mirex in hepatocytes and subcellular fractions in CD1 mouse liver
International Nuclear Information System (INIS)
Charles, A.K.; Rosenbaum, D.P.; Ashok, L.; Abraham, R.
1985-01-01
In vivo uptake and disposition of [ 14 C]mirex by CD1 mouse liver subcellular fractions and cells of different nuclear ploidy were examined following single or multiple doses of mirex injected intraperitoneally. Significant amounts of mirex were rapidly taken up by liver (21-29%), suggesting that liver is one of the primary sites of accumulation of the chemical. Among subcellular fractions, mirex was predominantly distributed in mitochondria and microsomes in the irreversibly bound form (about 20%), although its levels fluctuated considerably with time. Mirex was completely dissociated with trichloroacetic acid treatment from both nuclear and plasma membrane fractions, although the total uptake by these fractions was markedly high. The time course of uptake and concentration-dependent disposition of mirex revealed that polyploid hepatocytes selectively accumulated higher amounts of the chemical (two to three times) compared to diploid hepatocytes. The increased affinity of polyploid cells to mirex may indicate a greater susceptibility of this cell type to the chemical insult and also may suggest a possible early involvement of polyploids in the tumorigenic process in rodent livers
Uptake of exogenous spermidine by rat lungs perfused in situ
International Nuclear Information System (INIS)
Rannels, D.E.; Addison, J.L.
1987-01-01
Uptake of the polyamine spermidine (SPD) from the pulmonary circulation was characterized by using ventilated rat lungs perfused in situ with Krebs-Henseleit-bicarbonate buffer containing 4.5% bovine serum albumin, 5.6 mM glucose, and 20 amino acids at plasma levels. [ 14 C]SPD was accumulated by the lungs in a time- and concentration-dependent manner. The pathway of SPD uptake exhibited saturation kinetics with an apparent K/sub m/ in the range of 1 μM and a V/sub max/ of 450-540 pmol/g lung min. SPD uptake was inhibited by the naturally occurring polyamines putrescine and spermine (SPM) and by the inhibitor of polyamine synthesis, methyglyoxal bis(guanylhydrazone) (MGBG). Inhibition of SPD uptake by SPM followed competitive kinetics; although MGBG was also a competitive inhibitor of SPD uptake, MGBG was less effective than SPM. These observations indicate that SPD is taken up from the pulmonary circulation by a carrier-mediated pathway that is inhibited by other natural polyamines and by MGBG and exhibits by other natural polyamines and by MGBG and exhibits substrate affinity in the range of plasma SPD concentrations
Uptake of exogenous spermidine by rat lungs perfused in situ
Energy Technology Data Exchange (ETDEWEB)
Rannels, D.E.; Addison, J.L.
1987-01-01
Uptake of the polyamine spermidine (SPD) from the pulmonary circulation was characterized by using ventilated rat lungs perfused in situ with Krebs-Henseleit-bicarbonate buffer containing 4.5% bovine serum albumin, 5.6 mM glucose, and 20 amino acids at plasma levels. (/sup 14/C)SPD was accumulated by the lungs in a time- and concentration-dependent manner. The pathway of SPD uptake exhibited saturation kinetics with an apparent K/sub m/ in the range of 1 ..mu..M and a V/sub max/ of 450-540 pmol/g lung min. SPD uptake was inhibited by the naturally occurring polyamines putrescine and spermine (SPM) and by the inhibitor of polyamine synthesis, methyglyoxal bis(guanylhydrazone) (MGBG). Inhibition of SPD uptake by SPM followed competitive kinetics; although MGBG was also a competitive inhibitor of SPD uptake, MGBG was less effective than SPM. These observations indicate that SPD is taken up from the pulmonary circulation by a carrier-mediated pathway that is inhibited by other natural polyamines and by MGBG and exhibits by other natural polyamines and by MGBG and exhibits substrate affinity in the range of plasma SPD concentrations.
Han, Kyu B.
This work studied the relationship between surfactant, oil, and water, by building ternary phase diagrams, the goal of which was to identify the oil-in-water phase composition. The resulting nano-sized emulsion was coated with dicalcium phosphate by utilizing the ionic affinity between calcium ions and the emulsion surface. Since the desired function of the particle is as an oxygen carrier, the particle stability, oxygen capacity, and oxygen release rate were investigated. The first step in the process was to construct ternary phase diagrams with 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) and soy derived lecithin. The results showed that the lecithin surfactant formed an oil-in-water phase region that was 36 times greater than that of DOPA. With the desired phase composition set, the lecithin emulsion was extruded, resulting in a well-dispersed nanosized particle. A pH titration study of the emulsion found an optimized calcium phosphate coating condition at pH 8.8, at which, the calcium ion had a greater affinity for the emulsion surface than phosphate. A Hill plot was used to show calcium cooperativeness on the emulsion surface which suggested one calcium ion binds to one lecithin molecule. The lecithin emulsion particles were then coated with calcium phosphate using a layering technique that allowed for careful control of the coating thickness. The overall particle hydrodynamic radius was consistent with the growth of the calcium phosphate coating, from 8 nm to 28 nm. This observation was further supported with cryo-TEM measurements. The stability of the coated emulsion was tested in conditions that simulate practical thermal, physical, and time-dependent conditions. Throughout the tests, the coated emulsion exhibited a constant mono-dispersed particle size, while the uncoated emulsion size fluctuated greatly and exhibited increased polydispersion. The fast mixing method with the stopped-flow apparatus was employed to test the product as an oxygen carrier, and it
Uptake and degradation of natural surfactant by isolated rat granular pneumocytes
International Nuclear Information System (INIS)
Fisher, A.B.; Chander, A.; Reicherter, J.
1987-01-01
It has been previously shown that isolated granular pneumocytes internalize and degrade dipalmitoylphosphatidylcholine (DPPC) in synthetic lipid vesicles and reutilize degradation products for phosphatidylcholine (PC) synthesis. In this study, the authors evaluated the uptake and degradation of radiolabeled natural surfactant (NS) isolated from lung lavage after perfusing isolated rat lungs with [ 3 H]choline. Uptake of NS by isolated granular pneumocytes was increased approximately fourfold compared with synthetic liposomes, suggesting that physical form or a component (e.g., a protein) of NS plays a role in phospholipid uptake by these cells. Uptake was significantly decreased by metabolic inhibitors, indicating an energy requirement for this process. After 2-h incubation, the pattern of radioactivity in cells compared with NS showed a significant decrease in PC and DSPC and increase in free choline, choline phosphate, and CDP-choline. This pattern of metabolism indicates degradation of PC and metabolic reutilization of products. These studies support the hypothesis that alveolar phospholipids are accumulated and reutilized by granular pneumocytes for surfactant synthesis
Botulinum neurotoxin B recognizes its protein receptor with high affinity and specificity.
Jin, Rongsheng; Rummel, Andreas; Binz, Thomas; Brunger, Axel T
2006-12-21
Botulinum neurotoxins (BoNTs) are produced by Clostridium botulinum and cause the neuroparalytic syndrome of botulism. With a lethal dose of 1 ng kg(-1), they pose a biological hazard to humans and a serious potential bioweapon threat. BoNTs bind with high specificity at neuromuscular junctions and they impair exocytosis of synaptic vesicles containing acetylcholine through specific proteolysis of SNAREs (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors), which constitute part of the synaptic vesicle fusion machinery. The molecular details of the toxin-cell recognition have been elusive. Here we report the structure of a BoNT in complex with its protein receptor: the receptor-binding domain of botulinum neurotoxin serotype B (BoNT/B) bound to the luminal domain of synaptotagmin II, determined at 2.15 A resolution. On binding, a helix is induced in the luminal domain which binds to a saddle-shaped crevice on a distal tip of BoNT/B. This crevice is adjacent to the non-overlapping ganglioside-binding site of BoNT/B. Synaptotagmin II interacts with BoNT/B with nanomolar affinity, at both neutral and acidic endosomal pH. Biochemical and neuronal ex vivo studies of structure-based mutations indicate high specificity and affinity of the interaction, and high selectivity of BoNT/B among synaptotagmin I and II isoforms. Synergistic binding of both synaptotagmin and ganglioside imposes geometric restrictions on the initiation of BoNT/B translocation after endocytosis. Our results provide the basis for the rational development of preventive vaccines or inhibitors against these neurotoxins.
Zorzi, Alessandro; Middendorp, Simon J; Wilbs, Jonas; Deyle, Kaycie; Heinis, Christian
2017-07-17
The rapid renal clearance of peptides in vivo limits this attractive platform for the treatment of a broad range of diseases that require prolonged drug half-lives. An intriguing approach for extending peptide circulation times works through a 'piggy-back' strategy in which peptides bind via a ligand to the long-lived serum protein albumin. In accordance with this strategy, we developed an easily synthesized albumin-binding ligand based on a peptide-fatty acid chimera that has a high affinity for human albumin (K d =39 nM). This ligand prolongs the elimination half-life of cyclic peptides in rats 25-fold to over seven hours. Conjugation to a peptide factor XII inhibitor developed for anti-thrombotic therapy extends the half-life from 13 minutes to over five hours, inhibiting coagulation for eight hours in rabbits. This high-affinity albumin ligand could potentially extend the half-life of peptides in human to several days, substantially broadening the application range of peptides as therapeutics.
Zorzi, Alessandro; Middendorp, Simon J.; Wilbs, Jonas; Deyle, Kaycie; Heinis, Christian
2017-07-01
The rapid renal clearance of peptides in vivo limits this attractive platform for the treatment of a broad range of diseases that require prolonged drug half-lives. An intriguing approach for extending peptide circulation times works through a `piggy-back' strategy in which peptides bind via a ligand to the long-lived serum protein albumin. In accordance with this strategy, we developed an easily synthesized albumin-binding ligand based on a peptide-fatty acid chimera that has a high affinity for human albumin (Kd=39 nM). This ligand prolongs the elimination half-life of cyclic peptides in rats 25-fold to over seven hours. Conjugation to a peptide factor XII inhibitor developed for anti-thrombotic therapy extends the half-life from 13 minutes to over five hours, inhibiting coagulation for eight hours in rabbits. This high-affinity albumin ligand could potentially extend the half-life of peptides in human to several days, substantially broadening the application range of peptides as therapeutics.
Structural implications of hERG K+ channel block by a high-affinity minimally structured blocker
Helliwell, Matthew V.; Zhang, Yihong; El Harchi, Aziza; Du, Chunyun; Hancox, Jules C.; Dempsey, Christopher E.
2018-01-01
Cardiac potassium channels encoded by human ether-à-go-go–related gene (hERG) are major targets for structurally diverse drugs associated with acquired long QT syndrome. This study characterized hERG channel inhibition by a minimally structured high-affinity hERG inhibitor, Cavalli-2, composed of three phenyl groups linked by polymethylene spacers around a central amino group, chosen to probe the spatial arrangement of side chain groups in the high-affinity drug-binding site of the hERG pore. hERG current (IhERG) recorded at physiological temperature from HEK293 cells was inhibited with an IC50 of 35.6 nm with time and voltage dependence characteristic of blockade contingent upon channel gating. Potency of Cavalli-2 action was markedly reduced for attenuated inactivation mutants located near (S620T; 54-fold) and remote from (N588K; 15-fold) the channel pore. The S6 Y652A and F656A mutations decreased inhibitory potency 17- and 75-fold, respectively, whereas T623A and S624A at the base of the selectivity filter also decreased potency (16- and 7-fold, respectively). The S5 helix F557L mutation decreased potency 10-fold, and both F557L and Y652A mutations eliminated voltage dependence of inhibition. Computational docking using the recent cryo-EM structure of an open channel hERG construct could only partially recapitulate experimental data, and the high dependence of Cavalli-2 block on Phe-656 is not readily explainable in that structure. A small clockwise rotation of the inner (S6) helix of the hERG pore from its configuration in the cryo-EM structure may be required to optimize Phe-656 side chain orientations compatible with high-affinity block. PMID:29545312
Energy Technology Data Exchange (ETDEWEB)
Hussein El-Sayed, M
1984-07-01
Phosphatic sandstone of Qatrani area contains high concentrations of uranium and thorium (1450 and 870 ppm respectively). These elements were directly separated from a representative sample of the ore by percolation leaching. Separation made was carried out by using two different leaching reagents, citric and nitric acids for obtaining two separate concentrates of U and Th consecutively from the sample. Uranium was leached first by using citric acid where other rock ingredients were left intact. The effects of: (a) increasing acid input amounts and (b) increasing leaching solution volumes (dilution) on U leaching efficiency were studied. The results revealed that citric acid reaction upon phosphate is limited in spite of higher residual acidity reported in the leach liquors. Regarding uranium, its leaching efficiency increased by increasing acid amounts and/or leaching solution volumes while fixing the acid input amounts. The efficiency of U leaching is more pronounced in the second case than in the first. Increasing U leaching while phosphate dissolution is limited could be interpreted as that the relative complexing affinity of citrate anion for hexavalent uranium is by far much greater than with phosphate. Thorium was thereafter leached by using dilute solutions of nitric acid to avoid dissolution of nitric acid to avoid dissolution of impurities. Percolation leaching experiments were thus performed on the uranium-free samples in the columns used previously in uranium leaching. The effects of increasing acid amounts and increasing leach liquor recycles on Th (and P/sub 2/O/sub 5/) leaching efficiency were studied.
High-energy phosphate transfer in human muscle: diffusion of phosphocreatine
Gabr, Refaat E.; El-Sharkawy, AbdEl-Monem M.; Schär, Michael; Weiss, Robert G.; Bottomley, Paul A.
2011-01-01
The creatine kinase (CK) reaction is central to muscle energetics, buffering ATP levels during periods of intense activity via consumption of phosphocreatine (PCr). PCr is believed to serve as a spatial shuttle of high-energy phosphate between sites of energy production in the mitochondria and sites of energy utilization in the myofibrils via diffusion. Knowledge of the diffusion coefficient of PCr (DPCr) is thus critical for modeling and understanding energy transport in the myocyte, but DPC...
Hirota's solitons in the affine and the conformal affine Toda models
International Nuclear Information System (INIS)
Aratyn, H.; Constantinidis, C.P.; Ferreira, L.A.; Gomes, J.F.; Zimerman, A.H.
1993-01-01
We use Hirota's method formulated as a recursive scheme to construct a complete set of soliton solutions for the affine Toda field theory based on an arbitrary Lie algebra. Our solutions include a new class of solitons connected with two different types of degeneracies encountered in Hirota's perturbation approach. We also derive an universal mass formula for all Hirota's solutions to the affine Toda model valid for all underlying Lie groups. Embedding of the affine Toda model in the conformal affine Toda model plays a crucial role in this analysis. (orig.)
International Nuclear Information System (INIS)
Sisworo, Elsye L; Sisworo, Widjang H; Havid-Rasjid; Syamsul-Rizal; Komarudin-Idris
2002-01-01
A green house experiment was carried out on a simulated crop rotation system of upland rice-soybean-mungbean to determine the effect of P-derived from different phosphate rock (PR) sources and TSP using 32 P. The data obtained reveal that all the P-sources has a significant effect on the growth of all the three crops, expressed in dry weight, % P-total and total P-uptake (mg P pot -1 ). For the P-source it was shown that % P-derived from PR/TSP and their uptake (mg P pot -1 ) was quite high, showing that the PR s applied were of good reactivity. The residue of the PR s has also still a good effect on plant growth than that of TSP. The efficiency of PR s was far below that of TSP. This apparently was due to the high rate of application, ten times the rate of TSP. (author)
Improving image segmentation by learning region affinities
Energy Technology Data Exchange (ETDEWEB)
Prasad, Lakshman [Los Alamos National Laboratory; Yang, Xingwei [TEMPLE UNIV.; Latecki, Longin J [TEMPLE UNIV.
2010-11-03
We utilize the context information of other regions in hierarchical image segmentation to learn new regions affinities. It is well known that a single choice of quantization of an image space is highly unlikely to be a common optimal quantization level for all categories. Each level of quantization has its own benefits. Therefore, we utilize the hierarchical information among different quantizations as well as spatial proximity of their regions. The proposed affinity learning takes into account higher order relations among image regions, both local and long range relations, making it robust to instabilities and errors of the original, pairwise region affinities. Once the learnt affinities are obtained, we use a standard image segmentation algorithm to get the final segmentation. Moreover, the learnt affinities can be naturally unutilized in interactive segmentation. Experimental results on Berkeley Segmentation Dataset and MSRC Object Recognition Dataset are comparable and in some aspects better than the state-of-art methods.
Recent advances in phosphate laser glasses for high power applications
International Nuclear Information System (INIS)
Campbell, J.H.
1996-01-01
Recent advances in Nd-doped phosphate laser glasses for high-peak-power and high-average-power applications are reviewed. Compositional studies have progressed to the point that glasses can be tailored to have specific properties for specific applications. Non-radiative relaxation effects can be accurately modeled and empirical expressions have been developed to evaluate both intrinsic (structural) and extrinsic (contamination induced) relaxation effects. Losses due to surface scattering and bulk glass absorption have been carefully measured and can be accurately predicted. Improvements in processing have lead to high damage threshold (e.g. Pt inclusion free) and high thermal shock resistant glasses with improved edge claddings. High optical quality pieces up to 79 x 45 x 4cm 3 have been made and methods for continuous melting laser glass are under development
Variation for N Uptake System in Maize: Genotypic Response to N Supply
Garnett, Trevor; Plett, Darren; Conn, Vanessa; Conn, Simon; Rabie, Huwaida; Rafalski, J. Antoni; Dhugga, Kanwarpal; Tester, Mark A.; Kaiser, Brent N.
2015-01-01
An understanding of the adaptations made by plants in their nitrogen (N) uptake systems in response to reduced N supply is important to the development of cereals with enhanced N uptake efficiency (NUpE). Twenty seven diverse genotypes of maize (Zea mays, L.) were grown in hydroponics for 3 weeks with limiting or adequate N supply. Genotypic response to N was assessed on the basis of biomass characteristics and the activities of the nitrate (NO−3) and ammonium (NH+4) high-affinity transport systems. Genotypes differed greatly for the ability to maintain biomass with reduced N. Although, the N response in underlying biomass and N transport related characteristics was less than that for biomass, there were clear relationships, most importantly, lines that maintained biomass at reduced N maintained net N uptake with no change in size of the root relative to the shoot. The root uptake capacity for both NO−3 and NH+4 increased with reduced N. Transcript levels of putative NO−3 and NH+4 transporter genes in the root tissue of a subset of the genotypes revealed that predominately ZmNRT2 transcript levels responded to N treatments. The correlation between the ratio of transcripts of ZmNRT2.2 between the two N levels and a genotype's ability to maintain biomass with reduced N suggests a role for these transporters in enhancing NUpE. The observed variation in the ability to capture N at low N provides scope for both improving NUpE in maize and also to better understand the N uptake system in cereals.
Variation for N Uptake System in Maize: Genotypic Response to N Supply
Garnett, Trevor
2015-11-09
An understanding of the adaptations made by plants in their nitrogen (N) uptake systems in response to reduced N supply is important to the development of cereals with enhanced N uptake efficiency (NUpE). Twenty seven diverse genotypes of maize (Zea mays, L.) were grown in hydroponics for 3 weeks with limiting or adequate N supply. Genotypic response to N was assessed on the basis of biomass characteristics and the activities of the nitrate (NO−3) and ammonium (NH+4) high-affinity transport systems. Genotypes differed greatly for the ability to maintain biomass with reduced N. Although, the N response in underlying biomass and N transport related characteristics was less than that for biomass, there were clear relationships, most importantly, lines that maintained biomass at reduced N maintained net N uptake with no change in size of the root relative to the shoot. The root uptake capacity for both NO−3 and NH+4 increased with reduced N. Transcript levels of putative NO−3 and NH+4 transporter genes in the root tissue of a subset of the genotypes revealed that predominately ZmNRT2 transcript levels responded to N treatments. The correlation between the ratio of transcripts of ZmNRT2.2 between the two N levels and a genotype\\'s ability to maintain biomass with reduced N suggests a role for these transporters in enhancing NUpE. The observed variation in the ability to capture N at low N provides scope for both improving NUpE in maize and also to better understand the N uptake system in cereals.
The solutions of affine and conformal affine Toda field theory
International Nuclear Information System (INIS)
Papadopoulos, G.; Spence, B.
1994-02-01
We give new formulations of the solutions of the field equations of the affine Toda and conformal affine Toda theories on a cylinder and two-dimensional Minkowski space-time. These solutions are parameterised in terms of initial data and the resulting covariant phase spaces are diffeomorphic to the Hamiltonian ones. We derive the fundamental Poisson brackets of the parameters of the solutions and give the general static solutions for the affine theory. (authors). 10 refs
Ca2+ Transport by Mitochondria from L1210 Mouse Ascites Tumor Cells
Reynafarje, Baltazar; Lehninger, Albert L.
1973-01-01
Mitochondria isolated from the ascites form of L1210 mouse leukemia cells readily accumulate Ca2+ from the suspending medium and eject H+ during oxidation of succinate in the presence of phosphate and Mg2+, with normal stoichiometry between Ca2+ uptake and electron transport. Ca2+ loads up to 1600 ng-atoms per mg of protein are attained. As is the case in mitochondria from normal tissues, Ca2+ uptake takes precedence over oxidative phosphorylation. However, Ca2+ transport by the L-1210 mitochondria is unusual in other respects, which may possibly have general significance in tumor cells. The apparent affinity of the L1210 mitochondria for Ca2+ in stimulation of oxygen uptake is about 3-fold greater than in normal liver mitochondria; moreover, the maximal rate of Ca2+ transport is also considerably higher. Furthermore, when Ca2+ pulses are added to L1210 mitochondria in the absence of phosphate or other permeant anions, much larger amounts of Ca2+ are bound and H+ ejected per atom of oxygen consumed than in the presence of phosphate; up to 7 Ca2+ ions are bound per pair of electrons passing each energy-conserving site of the electron-transport chain. Such “superstoichiometry” of Ca2+ uptake can be accounted for by two distinct types of respiration-dependent interaction of Ca2+ with the L1210 mitochondria. One is the stimulation of oxygen consumption, which is achieved by relatively low concentrations of Ca2+ (Km ≅ 8 μM) and is accompanied by binding of Ca2+ up to 40 ng-atoms per mg of protein. The second process, also dependent on electron transport, is the binding of further Ca2+ from the medium in exchange with previously stored membrane-bound protons, in which the affinity for Ca2+ is much lower (Km ≅ 120 μM). PMID:4515933
Energy Technology Data Exchange (ETDEWEB)
Waki, A.; Fujibayashi, Y.; Yonekura, Y.; Sadato, N.; Ishii, Y.; Yokoyama, A
1997-10-01
To determine appropriate use of 2-[{sup 18}F]-fluoro-2-deoxy-D-glucose (FDG) in the diagnosis of malignant tumors, the mechanism of enhanced FDG uptake in tumor cells was reassessed using in vitro cultured cell lines and {sup 3}H-deoxyglucose (DG), in combination with possible parameters of aerobic and anaerobic energy production. The high DG uptake in the tumor cells reflected the dependency of energy production on anaerobic glycolysis, and paradoxically on low levels of aerobic oxidative phosphorylation in mitochondria. We discuss here factors underlying anaerobic glycolysis in tumor cells.
Methylcellulose-Directed Synthesis of Nanocrystalline Zeolite NaA with High CO₂ Uptake.
Shakarova, Dilshod; Ojuva, Arto; Bergström, Lennart; Akhtar, Farid
2014-07-28
Zeolite NaA nanocrystals with a narrow particle size distribution were prepared by template-free hydrothermal synthesis in thermo-reversible methylcellulose gels. The effects of the amount of methylcellulose, crystallization time and hydrothermal treatment temperature on the crystallinity and particle size distribution of the zeolite NaA nanocrystals were investigated. We found that the thermogelation of methylcellulose in the alkaline Na₂O-SiO₂-Al₂O₃-H₂O system played an important role in controlling the particle size. The synthesized zeolite nanocrystals are highly crystalline, as demonstrated by X-ray diffraction (XRD), and scanning electron microscopy (SEM) shows that the nanocrystals can also display a well-defined facetted morphology. Gas adsorption studies on the synthesized nanocrystalline zeolite NaA showed that nanocrystals with a size of 100 nm displayed a high CO₂ uptake capacity (4.9 mmol/g at 293 K at 100 kPa) and a relatively rapid uptake rate compared to commercially available, micron-sized particles. Low-cost nanosized zeolite adsorbents with a high and rapid uptake are important for large scale gas separation processes, e.g., carbon capture from flue gas.
Percel, P.J.; Parrett, N.A.; Plimpton, R.F.; Ockerman, H.W.; Krol, B.; Roon, P.S. van
1982-01-01
Yield, sensory and chemical properties of pork liver loaves manufactured using varying processing treatments (tumbling vs immersion) and phosphate levels (0 vs 6.4%) were studied. Tumbling significantly improved liver cure uptake, total cure and loaf cooked yield when compared to immersion as a
Influence of self-affine roughness on the friction coefficient of rubber at high sliding velocity
Palasantzas, G
2004-01-01
In this work we investigate the influence of self-affine roughness on the friction coefficient of a rubber body onto a solid surface at high speeds. The roughness is characterized by the rms amplitude w, the correlation length xi, and the roughness exponent H. It is shown that the friction
Different endothelin receptor affinities in dog tissues
International Nuclear Information System (INIS)
Loeffler, B.M.L.; Loehrer, W.
1991-01-01
Endothelin (ET) is a long-lasting potent vasoconstrictor-peptide. Here the authors report different binding affinities of endothelin-1 (ET-1) to ET-receptors of various dog tissues. Crude microsomal fractions were prepared after homogenisation of dog tissues in 50 mM Tris/HCl, 20 mM MnCl2, 1 mM EDTA, pH 7.4 by differential centrifugation. Aliquots of microsomal fractions (70 micrograms of protein) were incubated at 25 degrees C for 180 min in the presence of 20 pM 125I-ET-1 and various concentrations of cold ET-1. Four different ET-1 receptor binding affinities were found: adrenals, cerebrum, liver, heart, skeletal muscle and stomach microsomal membranes contained high affinity binding sites (Kd 50 - 80 pM, Bmax 60 - 250 fmol/mg). In cerebellum and spleen medium affinity ET-1 receptors (Kd 350 pM, Bmax 880 and 1200 fmol/mg respectively) were present. In comparison lung and kidney microsomes contained a low affinity ET-1 receptor (Kd 800 and 880 pM, Bmax 1600 and 350 fmol/mg). Receptors of even lower affinity were present in heart, intestine and liver microsomes with Kd values of 3 - 6 nM
Directory of Open Access Journals (Sweden)
Maryam Roza Yazdani
2017-12-01
Full Text Available This study examines zinc(II–chitosan complexes as a bio-sorbent for phosphate removal from aqueous solutions. The bio-sorbent is prepared and is characterized via Fourier Transform Infrared Spectroscopy (FT-IR, Scanning Electron Microscopy (SEM, and Point of Zero Charge (pHPZC–drift method. The adsorption capacity of zinc(II–chitosan bio-sorbent is compared with those of chitosan and ZnO–chitosan and nano-ZnO–chitosan composites. The effect of operational parameters including pH, temperature, and competing ions are explored via adsorption batch mode. A rapid phosphate uptake is observed within the first three hours of contact time. Phosphate removal by zinc(II–chitosan is favored when the surface charge of bio-sorbent is positive/or neutral e.g., within the pH range inferior or around its pHPZC, 7. Phosphate abatement is enhanced with decreasing temperature. The study of background ions indicates a minor effect of chloride, whereas nitrate and sulfate show competing effect with phosphate for the adsorptive sites. The adsorption kinetics is best described with the pseudo-second-order model. Sips (R2 > 0.96 and Freundlich (R2 ≥ 0.95 models suit the adsorption isotherm. The phosphate reaction with zinc(II–chitosan is exothermic, favorable and spontaneous. The complexation of zinc(II and chitosan along with the corresponding mechanisms of phosphate removal are presented. This study indicates the introduction of zinc(II ions into chitosan improves its performance towards phosphate uptake from 1.45 to 6.55 mg/g and provides fundamental information for developing bio-based materials for water remediation.
Energy Technology Data Exchange (ETDEWEB)
Murthy, T S; Cherian, S; Shivarudrappa, V; Subramanian, T K; Achari, P S [Bhabha Atomic Research Centre, Bombay (India). Primary Isotopes Section
1981-01-01
The labelled phosphate to be used for crop evaluation studies should have characteristics exactly similar to the industrial product employed in agriculture. For the preparation of /sup 32/P labelled compound from rock phosphate with high fluorine content, a number of parameters have been studied like particle size of the rock, temperature and amount of acid required, the curing time, etc. Because of the high reaction temperature, the curing time is reduced to experimental limits compared to the commercial product. This paper describes a method for the preparation of such a labelled phosphate and this yields a product with about 95% of the phosphate in the water soluble form.
Sawers, Ruairidh J H; Svane, Simon F; Quan, Clement; Grønlund, Mette; Wozniak, Barbara; Gebreselassie, Mesfin-Nigussie; González-Muñoz, Eliécer; Chávez Montes, Ricardo A; Baxter, Ivan; Goudet, Jerome; Jakobsen, Iver; Paszkowski, Uta
2017-04-01
Plant interactions with arbuscular mycorrhizal fungi have long attracted interest for their potential to promote more efficient use of mineral resources in agriculture. Their use, however, remains limited by a lack of understanding of the processes that determine the outcome of the symbiosis. In this study, the impact of host genotype on growth response to mycorrhizal inoculation was investigated in a panel of diverse maize lines. A panel of 30 maize lines was evaluated with and without inoculation with arbuscular mycorrhizal fungi. The line Oh43 was identified to show superior response and, along with five other reference lines, was characterized in greater detail in a split-compartment system, using 33 P to quantify mycorrhizal phosphorus uptake. Changes in relative growth indicated variation in host capacity to profit from the symbiosis. Shoot phosphate content, abundance of root-internal and -external fungal structures, mycorrhizal phosphorus uptake, and accumulation of transcripts encoding plant PHT1 family phosphate transporters varied among lines. Superior response in Oh43 is correlated with extensive development of root-external hyphae, accumulation of specific Pht1 transcripts and high phosphorus uptake by mycorrhizal plants. The data indicate that host genetic factors influence fungal growth strategy with an impact on plant performance. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.
Complex formation of uranium(VI) with fructose and glucose phosphates
International Nuclear Information System (INIS)
Koban, A.; Geipel, G.; Bernhard, G.; Fanghaenel, T.
2002-01-01
The uptake of heavy metals into plants is commonly quantified by the soil-plant transfer factor. Up to now little is known about the chemical speciation of actinides in plants. To compare the obtained spectroscopic data of uranium complexes in plants with model compounds, we investigate the complexation of uranium with relevant bioligands of various functionalities. A very important class of ligands consists of phosphate esters, which serve as phosphate group and energy transmitters as well as energy storage media in biological systems. Heavy metal ions bound to the phosphate esters can be transported into living cells and then deposited. Therefore, in our study we present the results of uranium complexation with glucose-6-phosphate (G6P), and fructose-6-phosphate (F6P) obtained by time-resolved laser-induced fluorescence spectroscopy (TRLFS). The experiments were performed at a fixed uranyl concentration (10 -5 M) as a function of the ligand concentrations (10 -5 to 10 -3 M) in a pH range from 2 to 4.5. For the glucose phosphate system we observed, using increasing ligand concentrations, a decrease in the fluorescence intensity and a small red shift of the emission bands. From this we conclude that the complexed uranyl glucose phosphate species show only minor or no fluorescence properties. The TRLFS spectra of the glucose phosphate samples indicated the presence of a single species with fluorescence properties. This species has a lifetime of approximately 1.5 μs and was identified as the free uranyl ion. An opposite phenomenon was observed for the fructose phosphate system: there was no decrease in fluorescence intensity. However, a strong red shift of the spectra was observed, illustrating the fluorescence properties of the uranyl fructose phosphate complex. The TRLFS spectra of the fructose phosphate system showed a second lifetime ( 2 2+ UO 2 (lig) x (2-y)+ + y H + (lig = sugar phosphate). Applying the mass action law and transformation to the logarithmic
Radioactivity of phosphate ores from Karatas-Mazidag phosphate deposit of Turkey
International Nuclear Information System (INIS)
Akyuez, T.; Varinlioglu, A.; Kose, A.; Akyuez, S.
2000-01-01
The specific activities of 238 U, 226 Ra, 232 Th and 40 K in the composite samples of phosphate ores of type I (grey-coloured ore, with high P 2 O 5 (21-35%) and low calcite content) and of type II (grey coloured calcite ore, with low P 2 O 5 content (5-17%)) of Karatas-Mazidag phosphate deposit, Turkey, have been determined by gamma spectrometry together with phosphatic animal feed ingredients. The concentrations of 238 U, 226 Ra, 232 Th and 40 K were found to be up to 557, 625, 26 and 297 Bq x kg -1 , respectively. Radium equivalent activities of samples were calculated and compared with those given in the literature. Uranium concentration of the individual phosphate samples, from which composite samples of ores of type I and II have been prepared, were found to show and increasing trend with increasing P 2 O 5 and F concentrations. (author)
Are Polyphosphates or Phosphate Esters Prebiotic Reagents?
Keefe, Anthony D.; Miller, Stanley L.
1995-01-01
It is widely held that there was a phosphate compound in prebiotic chemistry that played the role of adenosine triphosphate and that the first living organisms had ribose-phosphate in the backbone of their genetic material. However, there are no known efficient prebiotic synthesis of high-energy phosphates or phosphate esters. We review the occurrence of phosphates in nature, the efficiency of the volcanic synthesis of P4O10, the efficiency of polyphosphate synthesis by heating phosphate minerals under geological conditions, and the use of high-energy organic compounds such as cyanamide or hydrogen cyanide. These are shown to be inefficient processes especially when the hydrolysis of the polyphosphates is taken into account. For example, if a whole atmosphere of methane or carbon monoxide were converted to cyanide which somehow synthesized polyphosphates quantitatively, the polyphosphate concentration in the ocean would still have been insignificant. We also attempted to find more efficient high-energy polymerizing agents by spark discharge syntheses, but without success. There may still be undiscovered robust prebiotic syntheses of polyphosphates, or mechanisms for concentrating them, but we conclude that phosphate esters may not have been constituents of the first genetic material. Phosphoanhydrides are also unlikely as prebiotic energy sources.
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Cupisti A
2013-10-01
Full Text Available Adamasco Cupisti,1 Maurizio Gallieni,2 Maria Antonietta Rizzo,2 Stefania Caria,3 Mario Meola,4 Piergiorgio Bolasco31Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy; 2Nephrology and Dialysis Unit, San Carlo Borromeo Hospital, Milan, Italy; 3Territorial Department of Nephrology and Dialysis, ASL Cagliari, Italy; 4Sant'Anna School of Advanced Studies, University of Pisa, Pisa, ItalyAbstract: Prevention and correction of hyperphosphatemia is a major goal of chronic kidney disease–mineral and bone disorder (CKD–MBD management, achievable through avoidance of a positive phosphate balance. To this aim, optimal dialysis removal, careful use of phosphate binders, and dietary phosphate control are needed to optimize the control of phosphate balance in well-nourished patients on a standard three-times-a-week hemodialysis schedule. Using a mixed diffusive–convective hemodialysis tecniques, and increasing the number and/or the duration of dialysis tecniques are all measures able to enhance phosphorus (P mass removal through dialysis. However, dialytic removal does not equal the high P intake linked to the high dietary protein requirement of dialysis patients; hence, the use of intestinal P binders is mandatory to reduce P net intestinal absorption. Unfortunately, even a large dose of P binders is able to bind approximately 200–300 mg of P on a daily basis, so it is evident that their efficacy is limited in the case of an uncontrolled dietary P load. Hence, limitation of dietary P intake is needed to reach the goal of neutral phosphate balance in dialysis, coupled to an adequate protein intake. To this aim, patients should be informed and educated to avoid foods that are naturally rich in phosphate and also processed food with P-containing preservatives. In addition, patients should preferentially choose food with a low P-to-protein ratio. For example, patients could choose egg white or protein from a vegetable source
International Nuclear Information System (INIS)
Nam, Hyun Yeol; Jun, Sung Min; Pak, Kyoung June; Kim, In Joo
2017-01-01
Concurrent low brain and high liver uptake are sometimes observed on fluorine-18-labeled fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET). We investigated the potential clinical significance of this uptake pattern related to metabolic syndrome (MS). We retrospectively reviewed data from 264 consecutive males who had undergone general health check-ups, including FDG PET/CT scans. After an overnight fast, the men had their peripheral blood drawn and the levels of various laboratory parameters measured; an FDG PET/CT scan was performed on the same day. We measured the maximum standardized uptake values of the brain and liver from regions of interest manually placed over the frontal cortex at the level of the centrum semiovale and the right lobe of the liver parenchyma, respectively. Fasting blood glucose (FBG; odds ratio [OR] = 1.063, p < 0.001) and glycated hemoglobin (HbA1c; OR = 3.634, p = 0.010) were the strongest predictive factors for low brain FDG uptake, whereas waist circumference (OR = 1.200, p < 0.001) and γ-glutamyl transpeptidase (OR = 1.012, p = 0.001) were the strongest predictive factors for high liver uptake. Eleven subjects (4.2%) showed concurrent low brain and high liver FDG uptake, and all but one of these subjects (90.9%) had MS. Systolic blood pressure, waist circumference, FBG, triglyceride, alanine aminotransferase, insulin resistance (measured by homeostasis model assessment), insulin, HbA1c, and body mass index were higher in subjects with this FDG uptake pattern than in those without (all, p < 0.001). Concurrent low brain and high liver FDG uptake were closely associated with MS. Moreover, subjects with this pattern had higher values for various cardiovascular risk factors than did those without
Energy Technology Data Exchange (ETDEWEB)
Nam, Hyun Yeol [Dept. of Nuclear Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon (Korea, Republic of); Jun, Sung Min [Dept. of Nuclear Medicine, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan (Korea, Republic of); Pak, Kyoung June; Kim, In Joo [Dept. of Nuclear Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan (Korea, Republic of)
2017-04-15
Concurrent low brain and high liver uptake are sometimes observed on fluorine-18-labeled fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET). We investigated the potential clinical significance of this uptake pattern related to metabolic syndrome (MS). We retrospectively reviewed data from 264 consecutive males who had undergone general health check-ups, including FDG PET/CT scans. After an overnight fast, the men had their peripheral blood drawn and the levels of various laboratory parameters measured; an FDG PET/CT scan was performed on the same day. We measured the maximum standardized uptake values of the brain and liver from regions of interest manually placed over the frontal cortex at the level of the centrum semiovale and the right lobe of the liver parenchyma, respectively. Fasting blood glucose (FBG; odds ratio [OR] = 1.063, p < 0.001) and glycated hemoglobin (HbA1c; OR = 3.634, p = 0.010) were the strongest predictive factors for low brain FDG uptake, whereas waist circumference (OR = 1.200, p < 0.001) and γ-glutamyl transpeptidase (OR = 1.012, p = 0.001) were the strongest predictive factors for high liver uptake. Eleven subjects (4.2%) showed concurrent low brain and high liver FDG uptake, and all but one of these subjects (90.9%) had MS. Systolic blood pressure, waist circumference, FBG, triglyceride, alanine aminotransferase, insulin resistance (measured by homeostasis model assessment), insulin, HbA1c, and body mass index were higher in subjects with this FDG uptake pattern than in those without (all, p < 0.001). Concurrent low brain and high liver FDG uptake were closely associated with MS. Moreover, subjects with this pattern had higher values for various cardiovascular risk factors than did those without.
Lectin affinity electrophoresis.
Kobayashi, Yuka
2014-01-01
An interaction or a binding event typically changes the electrophoretic properties of a molecule. Affinity electrophoresis methods detect changes in the electrophoretic pattern of molecules (mainly macromolecules) that occur as a result of biospecific interactions or complex formation. Lectin affinity electrophoresis is a very effective method for the detection and analysis of trace amounts of glycobiological substances. It is particularly useful for isolating and separating the glycoisomers of target molecules. Here, we describe a sensitive technique for the detection of glycoproteins separated by agarose gel-lectin affinity electrophoresis that uses antibody-affinity blotting. The technique is tested using α-fetoprotein with lectin (Lens culinaris agglutinin and Phaseolus vulgaris agglutinin)-agarose gels.
International Nuclear Information System (INIS)
Salvucci, M.E.; Crafts-Brandner, S.J.
1991-01-01
A method for product analysis that eliminates a problematic step in the radiometric sucrose-phosphate synthase assay is described. The method uses chromatography on a boronate-derivatized high-performance liquid chromatography column to separate the labeled product, [14C]sucrose phosphate, from unreacted uridine 5'-diphosphate-[14C]glucose (UDP-Glc). Direct separation of these compounds eliminates the need for treatment of the reaction mixtures with alkaline phosphatase, thereby avoiding the problem of high background caused by contaminating phosphodiesterase activity in alkaline phosphatase preparations. The method presented in this paper can be applied to many UDP-Glc requiring enzymes; here the authors show its use for determining the activities of sucrose-phosphate synthase, sucrose synthase, and uridine diphosphate-glucose pyrophosphorylase in plant extracts
High-Affinity Accumulation of Chloroquine by Mouse Erythrocytes Infected with Plasmodium berghei
Fitch, Coy D.; Yunis, Norman G.; Chevli, Rekha; Gonzalez, Yolanda
1974-01-01
Washed erythrocytes infected with chloroquine-susceptible (CS) or with chloroquine-resistant (CR) P. berghei were used in model systems in vitro to study the accumulation of chloroquine with high affinity. The CS model could achieve distribution ratios (chloroquine in cells: chloroquine in medium) of 100 in the absence of substrate. 200—300 in the presence of 10 mM pyruvate or lactate, and over 600 in the presence of 1 mM glucose or glycerol. In comparable studies of the CR model, the distribution ratios were 100 in the absence of substrate and 300 or less in the presence of glucose or glycerol. The presence of lactate stimulated chloroquine accumulation in the CR model, whereas the presence of pyruvate did not. Lactate production from glucose and glycerol was undiminished in the CR model, and ATP concentrations were higher than in the CS model. Cold, iodoacetate, 2,4-dinitrophenol, or decreasing pH inhibited chloroquine accumulation in both models. These findings demonstrate substrate involvement in the accumulation of chloroquine with high affinity. In studies of the CS model, certain compounds competitively inhibited chloroquine accumulation, while others did not. This finding is attributable to a specific receptor that imposes structural constraints on the process of accumulation. For chloroquine analogues, the position and length of the side chain, the terminal nitrogen atom of the side chain, and the nitrogen atom in the quinoline ring are important determinants of binding to this receptor. PMID:4600044
High Affinity IgE-Fc Receptor alpha and gamma Subunit Interactions
International Nuclear Information System (INIS)
Rashid, A.; Housden, J. E. M.; Sabban, S.; Helm, B.
2014-01-01
Objective: To explore the relationships between the subunits (alpha, beta and gamma) of the high affinity IgE receptor (Fc and RI) and its ability to mediate transmembrane signaling. Study Design: Experimental study. Place and Duration of Study: Department of Molecular Biology and Biotechnology, University of Sheffield, UK, from 2008 to 2009. Methodology: The approach employed was to create a chimera (human alpha-gamma-gamma) using the extracellular (EC) domain of the human high affinity IgE receptor. The alpha subunit (huFc and RIalpha) of IgE receptor was spliced onto the rodent gamma TM and cytoplasmic domain (CD). This was transfected into the Rat Basophilic Leukemia cell line in order to assess the possibility of selectively activating cells transfected with this single pass construct for antigen induced mediator release. Results: The RBLs cell lines transfected with the huFc and RIalpha/gamma/gamma cDNA constructs were assessed for the cell surface expression of the huFc and RIalpha subunit and the response to the antigenic stimulus by looking for degranulation and intracellular Ca2+ mobilisation. The results obtained showed the absence of huFc and RIalpha subunit expression on the surface of transfected cells as seen by flowcytometric studies, beta-hexosaminidase assays and intracellular calcium mobilisation studies. Conclusion: In the present study the grounds for non-expression of huFc and RIalpha/gamma/gamma cDNA remains elusive but may be due to the fact that the human-rodent chimeric receptors are assembled differently than the endogenous rodent receptors as seen in study in which COS 7 cells were transfected with human/rat chimeric complexes. (author)
Yuan, Yue; Byrd, Catherine; Shen, Tong-Jian; Simplaceanu, Virgil; Tam, Tsuey Chyi S.; Ho, Chien
2013-01-01
The oxygen affinity of woolly mammoth hemoglobin (rHb WM) is less affected by temperature change than that of Asian elephant hemoglobin (rHb AE) or human adult hemoglobin (Hb A). We report here a biochemical-biophysical study of Hb A, rHb AE, rHb WM and three rHb WM mutants with amino acid substitutions at β/δ101 (β/δ101Gln→Glu, Lys, or Asp) plus a double and a triple mutant, designed to clarify the role of the β/δ101 residue. The β/δ101Gln residue is important for responding to allosteric effectors, such as phosphate, inositol hexaphosphate (IHP), and chloride. The rHb WM mutants studied generally have higher affinity for oxygen under various conditions of pH, temperature, and salt concentration, and in the presence or absence of organic phosphate, than do rHb WM, rHb AE and Hb A. Titrations for the O2 affinity of these mutant rHbs as a function of chloride concentration indicate a lower heterotopic effect of this anion due to the replacement of β/δ101Gln in rHb WM. The alkaline Bohr effect of rHb WM and its mutants is reduced by 20–50% compared to that of Hb A and is independent of changes in temperature, in contrast to what has been observed in the hemoglobins of most mammalian species, including human. The results of our study on the temperature dependence of the O2 affinity of rHb WM and its mutant rHbs illustrate the important role of β/δ101Gln in regulating the functional properties of these hemoglobins. PMID:24228693
International Nuclear Information System (INIS)
Cordis, G.A.; Das, D.K.
1987-01-01
In order to follow the energy metabolism and the levels of high-energy phosphate compounds in porcine myocardium subjected to ischemic insult, it was necessary to develop a high-performance liquid chromatography (HPLC) method where creatine phosphate (CP) and the adenine nucleotides could be measured simultaneously in a single run. Currently available ion-pair reverse-phase HPLC methods require a separate injection with a change in wavelength and mobile phase in order to measure the creatine phosphate, while baseline separation of AMP is lacking. The ion-exchange HPLC method includes a simultaneous determination, but the baseline drifts due to the gradient and baseline separation of AMP is not achieved. In the following ion-pair reverse-phase HPLC method, simultaneous measurements of porcine myocardial adenine nucleotides and creatine phosphate were achieved along with a stable baseline and homogeneous baseline separation of each measured compound, allowing accurate quantification
N-Oxide analogs of WAY-100635 : new high affinity 5-HT (1A) receptor antagonists
Oberwinkler - Marchais, Sandrine; Nowicki, B; Pike, VW; Halldin, C; Sandell, J; Chou, YH; Gulyas, B; Brennum, LT; Farde, L; Wikstrom, H V
2005-01-01
WAY-100635 [N-(2-(1-(4-(2-methoxyphenyl)piperazinyl)ethyl))-N-(2-pyridinyl)cyclohexanecarboxamide] 1 and its O-des-methyl derivative DWAY 2 are well-known high affinity 5-HT1A receptor antagonists. which when labeled with carbon-II (beta(+): t(1/2) 20.4min) in the carbonyl group are effective
Directory of Open Access Journals (Sweden)
N.B. Iannucci
2003-03-01
Full Text Available High-performance affinity matrices were obtained by attaching pseudobiospecific ligands to hollow-fibre membranes. The neutral protease contained in FlavourzymeTM was purified to homogeneity with Yellow 4R-HE affinity hollow-fibre membranes. Immobilisation of Red HE-3B allowed purification of a milk-clotting enzyme obtained by solid-state culture of Mucor bacilliformis. Copper immobilisation through iminodiacetic acid allowed fractionation of Biocon Bioconcentrated PlusTM to separate the pectinesterase-containing fraction. The productivity of the developed processes - 1900, 94 and 750 U/ml.min, respectively - was 10- to 15-fold higher than that achieved with the same ligands immobilised on agarose-based soft gels, mainly due to the shortening of the purification processes.
Liu, Lin; Lee, Wang-Sik; Doray, Balraj; Kornfeld, Stuart
2017-06-16
Several lysosomal enzymes currently used for enzyme replacement therapy in patients with lysosomal storage diseases contain very low levels of mannose 6-phosphate, limiting their uptake via mannose 6-phosphate receptors on the surface of the deficient cells. These enzymes are produced at high levels by mammalian cells and depend on endogenous GlcNAc-1-phosphotransferase α/β precursor to phosphorylate the mannose residues on their glycan chains. We show that co-expression of an engineered truncated GlcNAc-1-phosphotransferase α/β precursor and the lysosomal enzyme of interest in the producing cells resulted in markedly increased phosphorylation and cellular uptake of the secreted lysosomal enzyme. This method also results in the production of highly phosphorylated acid β-glucocerebrosidase, a lysosomal enzyme that normally has just trace amounts of this modification.
Directory of Open Access Journals (Sweden)
T.V.S.L. Satyavani
2016-03-01
Full Text Available Lithium ion battery technology has the potential to meet the requirements of high energy density and high power density applications. A continuous search for novel materials is pursued continually to exploit the latent potential of this technology. In this review paper, methods for preparation of Lithium Iron Phosphate are discussed which include solid state and solution based synthesis routes. The methods to improve the electrochemical performance of lithium iron phosphate are presented in detail.
International Nuclear Information System (INIS)
Trifi, Houda
2011-01-01
Phosphorus bioavailability is often limited in agricultural soils. In this work, two bacteria were isolated from Tunisian phosphogypsum (PG). These ones have the capacity to dissolve inorganic phosphate (CaHPO 4 and Ca 3 (PO 4 ) 2 ). This capacity is determined by the clear halo formation around colonies in NBRIP agar medium. To confirm the solubilization phenotype, the concentration of solubilized phosphate by isolates cultivated in NBRIP broth containing PG was measured. These two bacteria noted BRM17 and BRM18 are identified as Pantoea sp. and Pseudomonas sp, respectively. The results show that BRM17 solubilizes about 2 times more phosphate in broth NBRIP medium after 48 hours of incubation than BRM18. Tunisian phosphogypsum contains 1100 ppm of strontium (Sr). Sr toxicity on bacteria was determined by concentration that gives half-maximal inhibition of bacteria (IC 50 ). Compared with Cupriavidus metallidurans (bacteria tolerant to most of heavy metals), BRM17 and BRM18 cultivated in broth medium containing increasing concentrations of Sr were found tolerant to Sr. The potential of bioremediation is tested by the rate evaluation of Sr adsorption by these bacteria. The results show the high ability of BRM18 to adsorb Sr. The resistance of isolates to ionizing radiation is also determined by the exposure of bacterial cultures to various doses of gamma radiation. BRM17 is considered radioresistant while BRM18 is radiosensitive. The effect on seed germination of wheat and pea inoculated with bacteria was tested. No positive effect was detected. This study is considered with the use of BRM17 and BRM18 in a bioremediation process and the improvement of phosphate uptake by plants cultivated in polluted environments.