Science.gov

Sample records for active inorganic phosphate

  1. High inorganic phosphate causes DNMT1 phosphorylation and subsequent fibrotic fibroblast activation

    SciTech Connect

    Tan, Xiaoying; Xu, Xingbo; Zeisberg, Elisabeth M.; Zeisberg, Michael

    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.

  2. High inorganic phosphate causes DNMT1 phosphorylation and subsequent fibrotic fibroblast activation.

    PubMed

    Tan, Xiaoying; Xu, Xingbo; Zeisberg, Elisabeth M; Zeisberg, Michael

    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. Copyright © 2016. Published by Elsevier Inc.

  3. Depupylase Dop Requires Inorganic Phosphate in the Active Site for Catalysis.

    PubMed

    Bolten, Marcel; Vahlensieck, Christian; Lipp, Colette; Leibundgut, Marc; Ban, Nenad; Weber-Ban, Eilika

    2017-03-10

    Analogous to eukaryotic ubiquitination, proteins in actinobacteria can be post-translationally modified in a process referred to as pupylation, the covalent attachment of prokaryotic ubiquitin-like protein Pup to lysine side chains of the target protein via an isopeptide bond. As in eukaryotes, an opposing activity counteracts the modification by specific cleavage of the isopeptide bond formed with Pup. However, the enzymes involved in pupylation and depupylation have evolved independently of ubiquitination and are related to the family of ATP-binding and hydrolyzing carboxylate-amine ligases of the glutamine synthetase type. Furthermore, the Pup ligase PafA and the depupylase Dop share close structural and sequence homology and have a common evolutionary history despite catalyzing opposing reactions. Here, we investigate the role played by the nucleotide in the active site of the depupylase Dop using a combination of biochemical experiments and X-ray crystallographic studies. We show that, although Dop does not turn over ATP stoichiometrically with substrate, the active site nucleotide species in Dop is ADP and inorganic phosphate rather than ATP, and that non-hydrolyzable analogs of ATP cannot support the enzymatic reaction. This finding suggests that the catalytic mechanism is more similar to the mechanism of the ligase PafA than previously thought and likely involves the transient formation of a phosphorylated Pup-intermediate. Evidence is presented for a mechanism where the inorganic phosphate acts as the nucleophilic species in amide bond cleavage and implications for Dop function are discussed.

  4. Toxicological review of inorganic phosphates.

    PubMed

    Weiner, M L; Salminen, W F; Larson, P R; Barter, R A; Kranetz, J L; Simon, G S

    2001-08-01

    Inorganic phosphate salts are widely used as food ingredients and in a variety of commercial applications. The United States Food and Drug Administration (FDA) considers inorganic phosphates "Generally Recognized As Safe" (GRAS) (FDA, 1973a, 1979) [FDA: Food and Drug Administration 1973a. GRAS (Generally Recognized as Safe) food ingredients-phosphates. NTIS PB-221-224, FDA, Food and Drug Administration, 1979. Phosphates; Proposed Affirmation of and Deletion From GRAS Status as Direct and Human Food Ingredients. Federal Register 44 (244). 74845-74857, 18 December (1979)] and the European Union (EU) allows inorganic phosphates to be added directly to food (EU Directive 95/2/EC as amended by 98/72/EC). In this review, data on the acute, subchronic and chronic toxicity, genotoxicity, teratogenicity and reproductive toxicity from the published literature and from unpublished studies by the manufacturers are reviewed. Based on the toxicity data and similar chemistry, the inorganic phosphates can be separated into four major classes, consisting of monovalent salts, divalent salts, ammonium salts and aluminum salts. The proposed classification scheme supports the use of toxicity data from one compound to assess the toxicity of another compound in the same class. However, in the case of eye and skin irritation, the proposed classification scheme cannot be used because a wide range of responses exists within each class. Therefore, the eye and skin hazards associated with an individual inorganic phosphate should be assessed on a chemical-by-chemical basis. A large amount of toxicity data exists for all four classes of inorganic phosphates. The large and comprehensive database allows an accurate assessment of the toxicity of each class of inorganic phosphate. Overall, all four classes of inorganic phosphates exhibit low oral, inhalation and dermal toxicities. Based on these data, humans are unlikely to experience adverse effects when the daily phosphorus consumption remains

  5. Trypanosoma rangeli: differential expression of ecto-phosphatase activities in response to inorganic phosphate starvation.

    PubMed

    Dick, Claudia Fernanda; Dos-Santos, André Luiz Araújo; Fonseca-de-Souza, André L; Rocha-Ferreira, Juliana; Meyer-Fernandes, José Roberto

    2010-04-01

    In this work, we showed that living cells of Trypanosoma rangeli express different ecto-phosphatase activities in response to different inorganic phosphate (Pi) concentrations in the culture medium. The ecto-phosphatase activity from T. rangeli grown at low-Pi concentration was inhibited by the increase of the pH, while the ecto-phosphatase of the cells grown at high Pi concentration was not modulated by the change of the pH of the medium. Okadaic acid inhibited only the ecto-phosphatase activity from cells grown at low-Pi concentration but not the ecto-phosphatase activity from cells grown at high-Pi concentration. Accordingly, phosphatase activity from T. rangeli grown at low Pi concentration was able to hydrolyze P-serine and P-threonine at high rate but not P-tyrosine. The phosphatase activity from T. rangeli grown at high-Pi concentration was able to hydrolyze P-serine, P-threonine and P-tyrosine with the same rate. The addition of anterior midgut homogenate of Rhodnius prolixus on the epimastigotes suspension inhibited the enzyme activity of T. rangeli grown at low-Pi concentration. On the other hand, anterior midgut homogenate had no effect in the ecto-phosphatase of T. rangeli maintained at high-Pi concentration. Altogether, the results described here indicate that ecto-phosphatase activities hydrolyzing phosphorylated compounds present in the extracellular medium of T. rangeli are regulated by the external Pi concentration.

  6. Measurements of metabolically active inorganic phosphate in plants growing in natural and agronomic settings and under water stress. [Stromal Phosphate

    SciTech Connect

    Sharkey, T.D.

    1988-01-01

    At high rates of photosynthesis, the conflicting requirements of adenosine triphosphate (ATP) synthesis for phosphate and starch and sucrose synthesis for low phosphate, may limit the overall rate of photosynthesis. This is called feedback limitation of photosynthesis. A nonaqueous fractionation technique was used to measure stromal phosphate levels without contamination from vacuolar phosphate. Under normal conditions the stromal phosphate level was found to be 7mM. Under feedback limited photosynthesis, this value dropped to <1mM. In a related study, the effect of water stress on photosynthesis was examined. Water stress was shown to cause a decrease in total leaf photosynthesis, due not to a total loss of photosynthetic ability, but rather due to photosynthesis only occurring in patches of the leaf. Water stress was shown to cause a reduction in starch and sucrose synthesis. Since this decline can be reversed by increasing the CO{sub 2} level around the plant, this is proposed to be due to closing of stomata due to the water stress. (MHB)

  7. Inorganic Phosphate as an Important Regulator of Phosphatases

    PubMed Central

    Dick, Claudia Fernanda; Dos-Santos, André Luiz Araújo; Meyer-Fernandes, José Roberto

    2011-01-01

    Cellular metabolism depends on the appropriate concentration of intracellular inorganic phosphate (Pi). Pi starvation-responsive genes appear to be involved in multiple metabolic pathways, implying a complex Pi regulation system in microorganisms and plants. A group of enzymes is required for absorption and maintenance of adequate phosphate levels, which is released from phosphate esters and anhydrides. The phosphatase system is particularly suited for the study of regulatory mechanisms because phosphatase activity is easily measured using specific methods and the difference between the repressed and derepressed levels of phosphatase activity is easily detected. This paper analyzes the protein phosphatase system induced during phosphate starvation in different organisms. PMID:21755037

  8. A Mg(2+)-dependent ecto-phosphatase activity on the external surface of Trypanosoma rangeli modulated by exogenous inorganic phosphate.

    PubMed

    Fonseca-de-Souza, André L; Dick, Claudia Fernanda; Dos Santos, André Luiz Araújo; Meyer-Fernandes, José Roberto

    2008-08-01

    In this work, we characterized a Mg(2+)-dependent ecto-phosphatase activity present in live Trypanosoma rangeli epimastigotes. This enzyme showed capacity to hydrolyze the artificial substrate for phosphatases, p-nitrophenylphosphate (p-NPP). At saturating concentration of p-NPP, half-maximal p-NPP hydrolysis was obtained with 0.23mM Mg(2+). Ca(2+) had no effect on the basal phosphatase activity, could not substitute Mg(2+) as an activator and in contrast inhibited the p-NPP hydrolysis stimulated by Mg(2+). The dependence on p-NPP concentration showed a normal Michaelis-Menten kinetics for this phosphatase activity with values of V(max) of 8.94+/-0.36 nmol p-NP x h(-1) x 10(-7) cells and apparent K(m) of 1.04+/-0.16 mM p-NPP. Mg(2+)-dependent ecto-phosphatase activity was stimulated by the alkaline pH range. Experiments using inhibitors, such as, sodium fluoride, sodium orthovanadate and ammonium molybdate, inhibited the Mg(2+)-dependent ecto-phosphatase activity. Inorganic phosphate (Pi), a product of phosphatases, inhibited reversibly in 50% this activity. Okadaic acid and microcystin-LR, specific phosphoserine/threonine phosphatase inhibitors, inhibited significantly the Mg(2+)-dependent ecto-phosphatase activity. In addition, this phosphatase activity was able to recognize as substrates only o-phosphoserine and o-phosphothreonine, while o-phosphotyrosine was not a good substrate for this phosphatase. Epimastigote forms of T. rangeli exhibit a typical growth curve, achieving the stationary phase around fifth or sixth day and the Mg(2+)-dependent ecto-phosphatase activity decreased around 10-fold with the cell growth progression. Cells maintained at Pi-deprived medium (2 mM Pi) present Mg(2+)-dependent ecto-phosphatase activity approximately threefold higher than that maintained at Pi-supplemented medium (50 mM Pi).

  9. The effects of chronic inorganic and organic phosphate exposure on bactericidal activity of the coelomic fluid of the sea urchin Lytechinus variegatus (Lamarck) (Echinodermata: Echinoidea).

    PubMed

    Böttger, S Anne; McClintock, James B

    2009-07-01

    The sea urchin Lytechinus variegatus can survive chronic exposure to sodium phosphate (inorganic phosphate) concentrations as high as 3.2 mg L-1, and triethyl phosphate (organic phosphate) concentrations of 1000 mg L-1. However, chronic exposure to low (0.8 mg L-1 inorganic and 10 mg L-1 organic phosphate), medium (1.6 mg L-1 inorganic and 100 mg L-1 organic phosphate) or high (3.2 mg L-1 inorganic and 1000 mg L-1 organic phosphate) sublethal concentrations of these phosphates inhibit bactericidal clearance of the marine bacterium Vibrio sp. Bacteria were exposed to coelomic fluid collected from individuals maintained in either artificial seawater, or three concentrations of either inorganic phosphate or organic phosphate. Sterile marine broth, natural seawater and cell free coelomic fluid (cfCF) were employed as controls. Bacterial survival indices were measured at 0, 24 and 48 h periods once a week for four weeks. Bacteria were readily eliminated from the whole coelomic fluid (wCF) of individuals maintained in artificial seawater. Individuals maintained in inorganic phosphates were able to clear bacteria following a two week exposure period, while individuals maintained at even low concentrations of organic phosphates failed to clear all bacteria from their coelomic fluid. Exposure to phosphates represses antimicrobial defenses and may ultimately compromise survival of L. variegatus in the nearshore environment.

  10. Inorganic phosphate inhibits sympathetic neurotransmission in canine saphenous veins

    SciTech Connect

    Edoute, Y.; Vanhoutte, P.M.; Shepherd, J.T.

    1987-01-01

    Inorganic phosphate has been proposed as the initiator of metabolic vasodilatation in active skeletal muscle. The present study was primarily designed to determine if this substance has an inhibitory effect on adrenergic neurotransmission. Rings of canine saphenous veins were suspended for isometric tension recording in organ chambers. A comparison was made of the ability of inorganic phosphate (3 to 14 mM) to relax rings contracted to the same degree by electrical stimulation, exogenous norepinephrine, and prostaglandin F/sub 2..cap alpha../. The relaxation during electrical stimulation was significantly greater at all concentrations of phosphate. In strips of saphenous veins previously incubated with (/sup 3/H)norepinephrine, the depression of the contractile response caused by phosphate during electrical stimulated was accompanied by a significant reduction in the overflow of labeled neurotransmitter. Thus inorganic phosphate inhibits sympathetic neurotransmission and hence may have a key role in the sympatholysis in the active skeletal muscles during exercise. By contrast, in this preparation, it has a modest direct relaxing action on the vascular smooth muscle.

  11. Inorganic Phosphate and Sulfate Transport in S. cerevisiae.

    PubMed

    Samyn, D R; Persson, B L

    2016-01-01

    Inorganic ions such as phosphate and sulfate are essential macronutrients required for a broad spectrum of cellular functions and their regulation. In a constantly fluctuating environment microorganisms have for their survival developed specific nutrient sensing and transport systems ensuring that the cellular nutrient needs are met. This chapter focuses on the S. cerevisiae plasma membrane localized transporters, of which some are strongly induced under conditions of nutrient scarcity and facilitate the active uptake of inorganic phosphate and sulfate. Recent advances in studying the properties of the high-affinity phosphate and sulfate transporters by means of site-directed mutagenesis have provided further insight into the molecular mechanisms contributing to substrate selectivity and transporter functionality of this important class of membrane transporters.

  12. THE DISTRIBUTION OF INORGANIC PHOSPHATE IN AMPHIBIAN MUSCLE

    PubMed Central

    Briner, G. P.; Simon, Shirley E.; Shaw, F. H.

    1958-01-01

    The Na+, K+, and inorganic phosphate levels of the plasma and sartorius muscle of the toad Bufo marinus were determined. Soaking in normal Ringer brought about the usual cation shifts, but did not alter the level of inorganic phosphate in the cell. Increases in the external phosphate level brought about an increase in the internal phosphate, but the apparent phosphate space of muscle is somewhat smaller than the apparent Cl- space. Phosphate spaces were compared with inulin spaces and were found to be significantly greater. Alteration of the H+ concentration of the high phosphate Ringer did not alter the partition of phosphate across the cell membrane. These results have been found to be consistent with the theory of a three compartment system for muscle, wherein the tissue is assumed to consist of an extracellular phase, and two intracellular phases. The inorganic phosphate of the cell is assumed to be adsorbed onto the "ordered phase," and increments in organic phosphate found on raising the external level are assumed to take place in the "free intracellular phase." PMID:13514009

  13. Transport of inorganic phosphate in Leishmania infantum and compensatory regulation at low inorganic phosphate concentration.

    PubMed

    Russo-Abrahão, T; Alves-Bezerra, M; Majerowicz, D; Freitas-Mesquita, A L; Dick, C F; Gondim, K C; Meyer-Fernandes, J R

    2013-03-01

    Proliferation of Leishmania infantum depends on exogenous inorganic phosphate (P(i)) but little is known about energy metabolism and transport of P(i) across the plasma membrane in Leishmania sp. We investigated the kinetics of 32P(i) transport, the influence of H+ and K+ ionophores and inhibitors, and expression of the genes for the Na+:P(i) and H+:P(i) cotransporters. The proton ionophore FCCP, bafilomycin A1 (vacuolar ATPase inhibitor), nigericin (K+ ionophore) and SCH28080 (an inhibitor of H+, K(+)-ATPase) all inhibited the transport of P(i). This transport showed Michaelis-Menten kinetics with K0.5 and V(max) values of 0.016 +/- 0.002 mM and 564.9 +/- 18.06 pmol x h(-1) x 10(-7) cells, respectively. These values classify the P(i) transporter of L. infantum among the high-affinity transporters, a group that includes Pho84 of Saccharomyces cerevisiae. Two sequences were identified in the L. infantum genome that code for phosphate transporters. However, transcription of the PHO84 transporter was 10-fold higher than the PHO89 transporter in this parasite. Accordingly, P(i) transport and LiPho84 gene expression were modulated by environmental P(i) variations. These findings confirm the presence of a P(i) transporter in L. infantum, similar to PHO84 in S. cerevisiae, that contributes to the acquisition of inorganic phosphate and could be involved in growth and survival of the promastigote forms of L. infantum. This work provides the first description of a PHO84-like P(i) transporter in a Trypanosomatide parasite of the genus Leishmania, responsible for many infections worldwide.

  14. Inorganic Phosphate Prevents Erk1/2 and Stat3 Activation and Improves Sensitivity to Doxorubicin of MDA-MB-231 Breast Cancer Cells.

    PubMed

    Sapio, Luigi; Sorvillo, Luca; Illiano, Michela; Chiosi, Emilio; Spina, Annamaria; Naviglio, Silvio

    2015-09-01

    Due to its expression profile, triple-negative breast cancer (TNBC) is refractory to the most effective targeted therapies available for breast cancer treatment. Thus, cytotoxic chemotherapy represents the mainstay of treatment for early and metastatic TNBC. Therefore, it would be greatly beneficial to develop therapeutic approaches that cause TNBC cells to increase their sensitivity to cytotoxic drugs. Inorganic phosphate (Pi) is emerging as an important signaling molecule in many cell types. Interestingly, it has been shown that Pi greatly enhances the sensitivity of human osteosarcoma cell line (U2OS) to doxorubicin. We investigated the effects of Pi on the sensitivity of TNBC cells to doxorubicin and the underlying molecular mechanisms, carrying out flow cytometry-based assays of cell-cycle progression and cell death, MTT assays, direct cell number counting and immunoblotting experiments. We report that Pi inhibits the proliferation of triple-negative MDA-MB-231 breast cancer cells mainly by slowing down cell cycle progression. Interestingly, we found that Pi strongly increases doxorubicin-induced cytotoxicity in MDA-MB-231 cells by apoptosis induction, as revealed by a marked increase of sub-G1 population, Bcl-2 downregulation, caspase-3 activation and PARP cleavage. Remarkably, Pi/doxorubicin combination-induced cytotoxicity was dynamically accompanied by profound changes in Erk1/2 and Stat3 protein and phosphorylation levels. Altogether, our data enforce the evidence of Pi acting as a signaling molecule in MDA-MB-231 cells, capable of inhibiting Erk and Stat3 pathways and inducing sensitization to doxorubicin of TNBC cells, and suggest that targeting Pi levels at local sites might represent the rationale for developing effective and inexpensive strategies for improving triple-negative breast cancer therapy.

  15. Multifunctional phosphate-based inorganic-organic hybrid nanoparticles.

    PubMed

    Heck, Joachim G; Napp, Joanna; Simonato, Sara; Möllmer, Jens; Lange, Marcus; Reichardt, Holger M; Staudt, Reiner; Alves, Frauke; Feldmann, Claus

    2015-06-17

    Phosphate-based inorganic-organic hybrid nanoparticles (IOH-NPs) with the general composition [M](2+)[Rfunction(O)PO3](2-) (M = ZrO, Mg2O; R = functional organic group) show multipurpose and multifunctional properties. If [Rfunction(O)PO3](2-) is a fluorescent dye anion ([RdyeOPO3](2-)), the IOH-NPs show blue, green, red, and near-infrared fluorescence. This is shown for [ZrO](2+)[PUP](2-), [ZrO](2+)[MFP](2-), [ZrO](2+)[RRP](2-), and [ZrO](2+)[DUT](2-) (PUP = phenylumbelliferon phosphate, MFP = methylfluorescein phosphate, RRP = resorufin phosphate, DUT = Dyomics-647 uridine triphosphate). With pharmaceutical agents as functional anions ([RdrugOPO3](2-)), drug transport and release of anti-inflammatory ([ZrO](2+)[BMP](2-)) and antitumor agents ([ZrO](2+)[FdUMP](2-)) with an up to 80% load of active drug is possible (BMP = betamethason phosphate, FdUMP = 5'-fluoro-2'-deoxyuridine 5'-monophosphate). A combination of fluorescent dye and drug anions is possible as well and shown for [ZrO](2+)[BMP](2-)0.996[DUT](2-)0.004. Merging of functional anions, in general, results in [ZrO](2+)([RdrugOPO3]1-x[RdyeOPO3]x)(2-) nanoparticles and is highly relevant for theranostics. Amine-based functional anions in [MgO](2+)[RaminePO3](2-) IOH-NPs, finally, show CO2 sorption (up to 180 mg g(-1)) and can be used for CO2/N2 separation (selectivity up to α = 23). This includes aminomethyl phosphonate [AMP](2-), 1-aminoethyl phosphonate [1AEP](2-), 2-aminoethyl phosphonate [2AEP](2-), aminopropyl phosphonate [APP](2-), and aminobutyl phosphonate [ABP](2-). All [M](2+)[Rfunction(O)PO3](2-) IOH-NPs are prepared via noncomplex synthesis in water, which facilitates practical handling and which is optimal for biomedical application. In sum, all IOH-NPs have very similar chemical compositions but can address a variety of different functions, including fluorescence, drug delivery, and CO2 sorption.

  16. Precaecal phosphorus digestibility of inorganic phosphate sources in male broilers

    PubMed Central

    Bikker, P.; Spek, J. W.; Van Emous, R. A.; Van Krimpen, M. M.

    2016-01-01

    Abstract The aim of this study, comprising two experiments, was (1) to determine in Experiment 1 the relationship of incremental dietary P (phosphorus) content on precaecal digestible P in male broilers and (2) to determine in Experiment 2 the precaecal P digestibility of various inorganic P sources at marginal levels of P supply.In Experiment 1, a total of 260 male Ross 308 broilers were divided into groups of 10 birds per pen resulting in 8 replicates for treatment 1 and 6 replicates for treatments 2–4. Experimental diets were formulated to contain 4 incremental concentrations of digestible P by means of increasing concentrations of monocalcium phosphate (MCP). In the second experiment, 480-d-old male Ross 308 broilers were divided in groups of 12 birds per pen resulting in 16 replicates for the basal diet and 6 replicates for each test diet. A total of 4 inorganic P sources, MCP, monodicalcium phosphate (MDCP), dicalcium phosphate (DCP) and defluorinated phosphate (DFP) were added to the basal diet to determine the precaecal P digestibility. Three of the 4 inorganic P sources (MCP, MDCP and DCP) represented a mix of batches from different producers. At the end of both experiments, the chyme of the posterior part of the small intestine was collected. Digestibility of P and Ca was determined using titanium dioxide as indigestible marker.In Experiment 1, a reduction in precaecal digestibility of P was observed above an estimated precaecal digestible dietary P concentration of 4.8 g/kg.The precaecal P digestibility of the tested inorganic P sources in Experiment 2 was 78.3% for MCP, 59.0% for DCP, 70.7% for MDCP and 31.5% for DFP. PMID:27635437

  17. Precaecal phosphorus digestibility of inorganic phosphate sources in male broilers.

    PubMed

    Bikker, P; Spek, J W; Van Emous, R A; Van Krimpen, M M

    2016-12-01

    The aim of this study, comprising two experiments, was (1) to determine in Experiment 1 the relationship of incremental dietary P (phosphorus) content on precaecal digestible P in male broilers and (2) to determine in Experiment 2 the precaecal P digestibility of various inorganic P sources at marginal levels of P supply. In Experiment 1, a total of 260 male Ross 308 broilers were divided into groups of 10 birds per pen resulting in 8 replicates for treatment 1 and 6 replicates for treatments 2-4. Experimental diets were formulated to contain 4 incremental concentrations of digestible P by means of increasing concentrations of monocalcium phosphate (MCP). In the second experiment, 480-d-old male Ross 308 broilers were divided in groups of 12 birds per pen resulting in 16 replicates for the basal diet and 6 replicates for each test diet. A total of 4 inorganic P sources, MCP, monodicalcium phosphate (MDCP), dicalcium phosphate (DCP) and defluorinated phosphate (DFP) were added to the basal diet to determine the precaecal P digestibility. Three of the 4 inorganic P sources (MCP, MDCP and DCP) represented a mix of batches from different producers. At the end of both experiments, the chyme of the posterior part of the small intestine was collected. Digestibility of P and Ca was determined using titanium dioxide as indigestible marker. In Experiment 1, a reduction in precaecal digestibility of P was observed above an estimated precaecal digestible dietary P concentration of 4.8 g/kg. The precaecal P digestibility of the tested inorganic P sources in Experiment 2 was 78.3% for MCP, 59.0% for DCP, 70.7% for MDCP and 31.5% for DFP.

  18. Characterization of inorganic phosphate transport in osteoclast-like cells.

    PubMed

    Ito, Mikiko; Matsuka, Naoko; Izuka, Michiyo; Haito, Sakiko; Sakai, Yuko; Nakamura, Rie; Segawa, Hiroko; Kuwahata, Masashi; Yamamoto, Hironori; Pike, Wesley J; Miyamoto, Ken-ichi

    2005-04-01

    Osteoclasts possess inorganic phosphate (Pi) transport systems to take up external Pi during bone resorption. In the present study, we characterized Pi transport in mouse osteoclast-like cells that were obtained by differentiation of macrophage RAW264.7 cells with receptor activator of NF-kappaB ligand (RANKL). In undifferentiated RAW264.7 cells, Pi transport into the cells was Na+ dependent, but after treatment with RANKL, Na+-independent Pi transport was significantly increased. In addition, compared with neutral pH, the activity of the Na+-independent Pi transport system in the osteoclast-like cells was markedly enhanced at pH 5.5. The Na+-independent system consisted of two components with Km of 0.35 mM and 7.5 mM. The inhibitors of Pi transport, phosphonoformic acid, and arsenate substantially decreased Pi transport. The proton ionophores nigericin and carbonyl cyanide p-trifluoromethoxyphenylhydrazone as well as a K+ ionophore, valinomycin, significantly suppressed Pi transport activity. Analysis of BCECF fluorescence indicated that Pi transport in osteoclast-like cells is coupled to a proton transport system. In addition, elevation of extracellular K+ ion stimulated Pi transport, suggesting that membrane voltage is involved in the regulation of Pi transport activity. Finally, bone particles significantly increased Na+-independent Pi transport activity in osteoclast-like cells. Thus, osteoclast-like cells have a Pi transport system with characteristics that are different from those of other Na+-dependent Pi transporters. We conclude that stimulation of Pi transport at acidic pH is necessary for bone resorption or for production of the large amounts of energy necessary for acidification of the extracellular environment.

  19. Dual mechanism of ion permeation through VDAC revealed with inorganic phosphate ions and phosphate metabolites.

    PubMed

    Krammer, Eva-Maria; Vu, Giang Thi; Homblé, Fabrice; Prévost, Martine

    2015-01-01

    In the exchange of metabolites and ions between the mitochondrion and the cytosol, the voltage-dependent anion channel (VDAC) is a key element, as it forms the major transport pathway for these compounds through the mitochondrial outer membrane. Numerous experimental studies have promoted the idea that VDAC acts as a regulator of essential mitochondrial functions. In this study, using a combination of molecular dynamics simulations, free-energy calculations, and electrophysiological measurements, we investigated the transport of ions through VDAC, with a focus on phosphate ions and metabolites. We showed that selectivity of VDAC towards small anions including monovalent phosphates arises from short-lived interactions with positively charged residues scattered throughout the pore. In dramatic contrast, permeation of divalent phosphate ions and phosphate metabolites (AMP and ATP) involves binding sites along a specific translocation pathway. This permeation mechanism offers an explanation for the decrease in VDAC conductance measured in the presence of ATP or AMP at physiological salt concentration. The binding sites occur at similar locations for the divalent phosphate ions, AMP and ATP, and contain identical basic residues. ATP features a marked affinity for a central region of the pore lined by two lysines and one arginine of the N-terminal helix. This cluster of residues together with a few other basic amino acids forms a "charged brush" which facilitates the passage of the anionic metabolites through the pore. All of this reveals that VDAC controls the transport of the inorganic phosphates and phosphate metabolites studied here through two different mechanisms.

  20. Research and application of method of oxygen isotope of inorganic phosphate in Beijing agricultural soils.

    PubMed

    Tian, Liyan; Guo, Qingjun; Zhu, Yongguan; He, Huijun; Lang, Yunchao; Hu, Jian; Zhang, Han; Wei, Rongfei; Han, Xiaokun; Peters, Marc; Yang, Junxing

    2016-12-01

    Phosphorus (P) in agricultural ecosystems is an essential and limited element for plants and microorganisms. However, environmental problems caused by P accumulation as well as by P loss have become more and more serious. Oxygen isotopes of phosphate can trace the sources, migration, and transformation of P in agricultural soils. In order to use the isotopes of phosphate oxygen, appropriate extraction and purification methods for inorganic phosphate from soils are necessary. Here, we combined two different methods to analyze the oxygen isotopic composition of inorganic phosphate (δ(18)OP) from chemical fertilizers and different fractions (Milli-Q water, 0.5 mol L(-1) NaHCO3 (pH = 8.5), 0.1 mol L(-1) NaOH and 1 mol L(-1) HCl) of agricultural soils from the Beijing area. The δ(18)OP results of the water extracts and NaHCO3 extracts in most samples were close to the calculated equilibrium value. These phenomena can be explained by rapid P cycling in soils and the influence of chemical fertilizers. The δ(18)OP value of the water extracts and NaHCO3 extracts in some soil samples below the equilibrium value may be caused by the hydrolysis of organic P fractions mediated by extracellular enzymes. The δ(18)OP values of the NaOH extracts were above the calculated equilibrium value reflecting the balance state between microbial uptake of phosphate and the release of intracellular phosphate back to the soil. The HCl extracts with the lowest δ(18)OP values and highest phosphate concentrations indicated that the HCl fraction was affected by microbial activity. Hence, these δ(18)Op values likely reflected the oxygen isotopic values of the parent materials. The results suggested that phosphate oxygen isotope analyses could be an effective tool in order to trace phosphate sources, transformation processes, and its utilization by microorganisms in agricultural soils.

  1. Biological effects of inorganic phosphate: potential signal of toxicity.

    PubMed

    Hong, Seong-Ho; Park, Sung-Jin; Lee, Somin; Kim, Sanghwa; Cho, Myung-Haing

    2015-02-01

    Inorganic phosphate (Pi) plays crucial roles in several biological processes and signaling pathways. Pi uptake is regulated by sodium-dependent phosphate (Na/Pi) transporters (NPTs). Moreover, Pi is used as a food additive in food items such as sausages, crackers, dairy products, and beverages. However, the high serum concentration of phosphate (> 5.5 mg/dL) can cause adverse renal effects, cardiovascular effects including vascular or valvular calcification, and stimulate bone resorption. In addition, Pi can also alter vital cellular signaling, related to cell growth and cap-dependent protein translation. Moreover, intake of dietary Pi, whether high (1.0%) or low (0.1%), affects organs in developing mice, and is related to tumorigenesis in mice. The recommended dietary allowance (RDA) of Pi is the daily dietary intake required to maintain levels above the lower limit of the range of normal serum Pi concentration (2.7 mg/dL) for most individuals (97-98%). Thus, adequate intake of Pi (RDA; 700 mg/day) and maintenance of normal Pi concentration (2.7-4.5 mg/dL) are important for health and prevention of diseases caused by inadequate Pi intake.

  2. Dual Mechanism of Ion Permeation through VDAC Revealed with Inorganic Phosphate Ions and Phosphate Metabolites

    PubMed Central

    Krammer, Eva-Maria; Vu, Giang Thi; Homblé, Fabrice; Prévost, Martine

    2015-01-01

    In the exchange of metabolites and ions between the mitochondrion and the cytosol, the voltage-dependent anion channel (VDAC) is a key element, as it forms the major transport pathway for these compounds through the mitochondrial outer membrane. Numerous experimental studies have promoted the idea that VDAC acts as a regulator of essential mitochondrial functions. In this study, using a combination of molecular dynamics simulations, free-energy calculations, and electrophysiological measurements, we investigated the transport of ions through VDAC, with a focus on phosphate ions and metabolites. We showed that selectivity of VDAC towards small anions including monovalent phosphates arises from short-lived interactions with positively charged residues scattered throughout the pore. In dramatic contrast, permeation of divalent phosphate ions and phosphate metabolites (AMP and ATP) involves binding sites along a specific translocation pathway. This permeation mechanism offers an explanation for the decrease in VDAC conductance measured in the presence of ATP or AMP at physiological salt concentration. The binding sites occur at similar locations for the divalent phosphate ions, AMP and ATP, and contain identical basic residues. ATP features a marked affinity for a central region of the pore lined by two lysines and one arginine of the N-terminal helix. This cluster of residues together with a few other basic amino acids forms a “charged brush” which facilitates the passage of the anionic metabolites through the pore. All of this reveals that VDAC controls the transport of the inorganic phosphates and phosphate metabolites studied here through two different mechanisms. PMID:25860993

  3. [Sodium-dependent inorganic phosphate transporters and biomineralization].

    PubMed

    Tatsumi, Sawako; Fujii, Osamu; Miyagawa, Atsumi; Miyamoto, Kenichi

    2014-02-01

    Phosphate (Pi), one of most abundant anions in living organisms, plays a crucial role in biomineralization. An adequate plasma Pi concentration is required to maintain the calcium × phosphate ion product within a range sufficient for physiological bone mineralization, but an increase in the calcium × phosphate product in extracellular fluids above a certain threshold can predispose to extraskeletal calcification. Membrane transport systems for Pi transport are key elements in maintaining homeostasis of Pi in organisms. Members of two families of solute carrier (SLC) proteins (SLC20 and SLC34) act as Na⁺ -dependent, secondary-active cotransporters to transport Pi across cell membranes in mammals. This review summarizes the role of SLC20 and SCL34 proteins on biomineralization.

  4. Effect of altitude on brain intracellular pH and inorganic phosphate levels.

    PubMed

    Shi, Xian-Feng; Carlson, Paul J; Kim, Tae-Suk; Sung, Young-Hoon; Hellem, Tracy L; Fiedler, Kristen K; Kim, Seong-Eun; Glaeser, Breanna; Wang, Kristina; Zuo, Chun S; Jeong, Eun-Kee; Renshaw, Perry F; Kondo, Douglas G

    2014-06-30

    Normal brain activity is associated with task-related pH changes. Although central nervous system syndromes associated with significant acidosis and alkalosis are well understood, the effects of less dramatic and chronic changes in brain pH are uncertain. One environmental factor known to alter brain pH is the extreme, acute change in altitude encountered by mountaineers. However, the effect of long-term exposure to moderate altitude has not been studied. The aim of this two-site study was to measure brain intracellular pH and phosphate-bearing metabolite levels at two altitudes in healthy volunteers, using phosphorus-31 magnetic resonance spectroscopy ((31)P-MRS). Increased brain pH and reduced inorganic phosphate (Pi) levels were found in healthy subjects who were long-term residents of Salt Lake City, UT (4720ft/1438m), compared with residents of Belmont, MA (20ft/6m). Brain intracellular pH at the altitude of 4720ft was more alkaline than that observed near sea level. In addition, the ratio of inorganic phosphate to total phosphate signal also shifted toward lower values in the Salt Lake City region compared with the Belmont area. These results suggest that long-term residence at moderate altitude is associated with brain chemical changes.

  5. Effect of altitude on brain intracellular pH and inorganic phosphate levels

    PubMed Central

    Shi, Xian-Feng; Carlson, Paul J.; Kim, Tae-Suk; Sung, Young-Hoon; Hellem, Tracy L.; Fiedler, Kristen K.; Kim, Seong-Eun; Glaeser, Breanna; Wang, Kristina; Zuo, Chun S.; Jeong, Eun-Kee; Renshaw, Perry F.; Kondo, Douglas G.

    2015-01-01

    Normal brain activity is associated with task-related pH changes. Although central nervous system syndromes associated with significant acidosis and alkalosis are well understood, the effects of less dramatic and chronic changes in brain pH are uncertain. One environmental factor known to alter brain pH is the extreme, acute change in altitude encountered by mountaineers. However, the effect of long-term exposure to moderate altitude has not been studied. The aim of this two-site study was to measure brain intracellular pH and phosphate-bearing metabolite levels at two altitudes in healthy volunteers, using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Increased brain pH and reduced inorganic phosphate (Pi) levels were found in healthy subjects who were long-term residents of Salt Lake City, UT (4720 ft/1438 m), compared with residents of Belmont, MA (20 ft/6 m). Brain intracellular pH at the altitude of 4720 ft was more alkaline than that observed near sea level. In addition, the ratio of inorganic phosphate to total phosphate signal also shifted toward lower values in the Salt Lake City region compared with the Belmont area. These results suggest that long-term residence at moderate altitude is associated with brain chemical changes. PMID:24768210

  6. Inorganic phosphate homeostasis. Renal adaptation to the dietary intake in intact and thyroparathyroidectomized rats.

    PubMed Central

    Tröhler, U; Bonjour, J P; Fleisch, H

    1976-01-01

    The possibility of renal tubular adaptation to variations in dietary inorganic phosphate (Pi) was investigated in intact and thyroparathyroidectomized (TPTX) rats pair-fed diets containing low, normal, and high amounts of Pi for periods up to 10 days. Clearances were measured before and during active i.v. infusions with Pi in conscious animals. Thus tubular reabsorption of phosphate (TRPi) could be assessed over a wide range of plasma phosphate concentrations ([Pi]P1). It was found that the renal tubule could adapt its capacity to transport Pi according to the dietary Pi: TRPi was always higher, for a given [Pi]P1, in the animals fed low than in those fed higher Pi diets. This diet-induced modification also occurred in the absence of thyroparathyroid glands, in the presence of the same calcemia and urinary pH, and during marked extracellular volume expansion. A time-course study in rats TPTX both before and during the administration of the experimental diets showed that a difference in the tubular handling of Pi was detectable as early as 3 days after switching the animals from a normal to low- or high-Pi diets. These results indicate that factors other than parathyroid hormone are implicated in the tubular response to variations in the dietary intake of inorganic phosphate. PMID:3518

  7. Inorganic phosphate transport in matrix vesicles from bovine articular cartilage.

    PubMed

    Solomon, D H; Browning, J A; Wilkins, R J

    2007-06-01

    In mineralizing tissues such as growth plate cartilage extracellular organelles derived from the chondrocyte membrane are present. These matrix vesicles (MV), possess membrane transporters that accumulate Ca(2+) and inorganic phosphate (P(i)), and initiate the formation of hydroxyapatite crystals. MV are also present in articular cartilage, and hydroxyapatite crystals are believed to promote cartilage degradation in osteoarthritic joints. This study characterizes P(i) transport in MV derived from articular cartilage. Matrix vesicles were harvested from collagenase digests of bovine articular cartilage by serial centrifugation. P(i) uptake by MV was measured using radioactive phosphate ((33)[P]HPO(4)(2-)). The Na(+) dependence, pH sensitivity and effects of P(i) analogues that inhibit P(i) transport were determined. P(i) uptake was temperature-sensitive and comprised Na(+)-dependent and Na(+)-independent components. The Na(+)-dependent component saturated at high extracellular P(i) concentrations, with a K(m) of 0.16 mM. In Na(+)-free solutions, uptake did not fully saturate implying that carrier-mediated uptake is supplemented by a diffusive pathway. Uptake was inhibited by phosphonoacetate and arsenate, although a fraction of Na(+)-independent P(i) uptake persisted. Total P(i) uptake was maximal at pH 6.5, and reduced at more acidic or alkaline values, representing inhibition of both components. These properties are highly similar to those of P(i) uptake by chondrocytes, suggesting that MV inherit P(i) transporters of the chondrocyte membrane from which they are derived. Na(+)-independent P(i) uptake has not previously been described in MV from growth plate cartilage and is relatively uncharacterized, but warrants further attention in articular cartilage, given its likely role in initiating inappropriate mineral formation.

  8. Inhibition of Recombinant Aldose-6-Phosphate Reductase from Peach Leaves by Hexose-Phosphates, Inorganic Phosphate and Oxidants.

    PubMed

    Hartman, Matías D; Figueroa, Carlos M; Arias, Diego G; Iglesias, Alberto A

    2017-01-01

    Glucitol, also known as sorbitol, is a major photosynthetic product in plants from the Rosaceae family. This sugar alcohol is synthesized from glucose-6-phosphate by the combined activities of aldose-6-phosphate reductase (Ald6PRase) and glucitol-6-phosphatase. In this work we show the purification and characterization of recombinant Ald6PRase from peach leaves. The recombinant enzyme was inhibited by glucose-1-phosphate, fructose-6-phosphate, fructose-1,6-bisphosphate and orthophosphate. Oxidizing agents irreversibly inhibited the enzyme and produced protein precipitation. Enzyme thiolation with oxidized glutathione protected the enzyme from insolubilization caused by diamide, while incubation with NADP+ (one of the substrates) completely prevented enzyme precipitation. Our results suggest that Ald6PRase is finely regulated to control carbon partitioning in peach leaves. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  9. Calcium-Activated Phosphate Uptake in Contracting Corn Mitochondria 1

    PubMed Central

    Truelove, B.; Hanson, J. B.

    1966-01-01

    The phosphate inhibition of succinate-powered contraction in corn mitochondria can be reversed with calcium. Associated with this reversal is an accumulation of phosphate and calcium. Both ions are essential for accumulation, although strontium will partially substitute for calcium. Arsenate does not substitute for phosphate except in producing the inhibition of contraction. The antibiotics oligomycin and aurovertin do not block the phosphate inhibition of contraction or the calcium-activated phosphate uptake associated with the release of the inhibition. Dinitrophenol uncouples the phosphate uptake but permits full contraction. Calcium promotes inorganic phosphate accumulation in root tissue as well as in mitochondria. The results are discussed from the viewpoint of theories of calcium reaction with high energy intermediates of oxidative phosphorylation. It is concluded that calcium probably reacts with X∼P in corn mitochondria, rather than with X∼I as with animal mitochondria. PMID:16656343

  10. Standardized total tract digestibility of phosphorus in various inorganic phosphates fed to growing pigs.

    PubMed

    Kwon, Woong Bi; Kim, Beob Gyun

    2017-06-01

    An experiment was conducted to determine the standardized total tract digestibility (STTD) of phosphorus (P) in five sources of inorganic phosphate fed to growing pigs, including dicalcium phosphate (DCP), monodicalcium phosphate (MDCP), monocalcium phosphate (MCP), tricalcium phosphate (TCP) and monosodium phosphate (MSP, reagent grade). Six barrows (42.4 ± 1.1 kg) individually housed in metabolism crates were allotted to a 6 × 6 Latin square design with six dietary treatments and six periods. Each experimental period consisted of a 4 day adaptation period and a 5 day collection period. The five experimental diets contained 0.24 to 0.34% of P from each inorganic phosphate as a sole source of P. A P-free diet was also prepared to estimate the basal endogenous loss of P. The STTD of P in MSP (94.9%) was not different from the STTD of P in MCP (93.0%), but was greater (P < 0.05) than that in DCP, MDCP and TCP (87.0, 86.5 and 71.3%, respectively). In conclusion, digestibility of P in reagent-grade MSP was greater than that in feed-grade inorganic phosphates such as DCP, MDCP and TCP, and digestibility of P in DCP and MDCP was greater than that in the TCP. © 2017 Japanese Society of Animal Science.

  11. Study of Acid Phosphatase in Solubilization of Inorganic Phosphates by Piriformospora indica.

    PubMed

    Seshagiri, Swetha; Tallapragada, Padmavathi

    2017-01-02

    Phosphorus is an essential plant macronutrient present in the soil. Only a small portion of phosphorus in soil is taken up by plants and the rest of it becomes unavailable to plants as it is immobilized. Phosphate solubilizing microorganisms play a vital role in converting the insoluble form of phosphates to the soluble form. The present paper reports the solubilization of tricalcium phosphate, rock phosphate, single super phosphate, zinc phosphate and aluminum phosphate by Piriformospora indica with the production of organic acids as well as acid phosphatase. The amount of phosphate released (4.73 mg ml(-1)) and titratable acidity (0.12%) was found to be the highest in the case of single super phosphate as compared to other phosphate sources. High performance liquid chromatography (HPLC) revealed the presence of oxalic acid, lactic acid, citric acid and succinic acid in the media. Highest phosphatase activity was observed with the cell membrane extract of the organism in the presence of zinc phosphate.

  12. Availability of phosphorus from selected inorganic phosphate to juvenile abalone, Haliotis discus hannai ino.

    NASA Astrophysics Data System (ADS)

    Bei-Ping, Tan; Kang-Sen, Mai; Wei, Xu

    2002-06-01

    The availability of phosphorus to juvenile abalone, Haliotis discus hannai from primary, secondary and tertiary calcium phosphate, primary sodium or potassium phosphate separately or in combination was determined in a 120-day feeding trial. Seven semi-purified diets were formulated to contain relatively constant dietary phosphorus, ranging from 0.78%-0.82%. The concentrations of dietary phosphorus were presumed to be slightly below the requirement for abalone. A brown alga, Laminaria japonica, was used as a control diet. Abalone juveniles of silimar size (average weight 1.18 g; average shell length 18.74 mm) were distributed in a single-pass, flow-through system using a completely randomized design with eight treatments and three replicates each treatment. The survival ranged from 71.1% to 81.1%, and was not significantly (P>0.05) related to dietary treatment. However, the weight gain rate (41.72%-65.02%), daily increment in shell length (36.87-55.07 μm) and muscle RNA-DNA ratio (3.44-4.69) were significantly (P<0.05) affected by dietary treatment. Soft body alkaline phosphatase activity (10.9-19.8 U/g wet tissue) and carcass levels of lipid (7.71%-9.33%) and protein (46.68%-49.35%) were significantly (P<0.05) responsive to available phosphorus of the diets. Dietary treatment had significant effect (P<0.05) on concentrations of phosphorus in the whole body (WB) and soft body (SB). Apparent digestibility coefficients (45%-97%) of phosphorus were also significantly (P<0.05) different between dietary treatments. The results indicated that among these inorganic compounds, primary calcium, potassium and sodium phosphates separately or in combination could be utilized effectively by juvenile abalone as dietary phosphorus sources (availability ranging from 87%-97%). However, secondary and tertiary calcium phosphates were found to be low in availability, the values being 45% and 77%, repectively.

  13. Inorganic chemically active adsorbents (ICAAs)

    SciTech Connect

    Ally, M.R.; Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  14. Oxygen Isotopic Composition of Dissolved Inorganic Phosphate in the Monterey Bay and California Current

    NASA Astrophysics Data System (ADS)

    McLaughlin, K.; Paytan, A.; Kendall, C.

    2001-12-01

    The marine biogeochemical cycle of phosphorus (P) is intricately linked to the atmospheric abundance of CO2 through its role as an important major nutrient. Phosphorus is considered to be a limiting nutrient in some oceanic systems (Cotner et al., 1997; Karl et al., 1995; Michaels et al., 1996; Wu et al., 2000) and is possibly the ultimate limiting macronutrient for marine productivity (Broecker and Peng, 1982; Delaney, 1998; Toggweiler, 1999; Tyrrell, 1999). Despite the recognition of the important role P plays in regulating marine productivity and thus the "biological pump" relatively little is known about P cycling within the ocean. We have mapped spatial and temporal variations in the oxygen isotopic composition of phosphate within the Monterey Bay and along a transect in the California Current. The P-O bond is resistant to inorganic hydrolysis and, in the temperature range of the ocean, is only broken by enzyme mediated reactions. Therefore, the d18O of inorganic phosphate should reflect the degree of recycling of phosphate within the ecosystem where greater recycling corresponds to increased equilibration with d18O of seawater. We have applied a method for extraction of dissolved inorganic phosphate from seawater and purification to silver phosphate for oxygen isotopic analysis (McLaughlin et al., 2000). These results are the first step in determining how phosphate recycling varies spatially and throughout the water column.

  15. Novel organic polymer-inorganic hybrid material zinc poly(styrene-phenylvinylphosphonate)-phosphate prepared with a simple method

    SciTech Connect

    Huang Jing; Fu Xiangkai; Wang Gang; Miao Qiang

    2011-09-15

    A novel type of organic polymer-inorganic hybrid material layered crystalline zinc poly(styrene-phenylvinylphosphonate)-phosphate (ZnPS-PVPP) was synthesized under mild conditions in the absence of any template. And the ZnPS-PVPP were characterized by FT-IR, diffusion reflection UV-vis, AAS, N{sub 2} volumetric adsorption, SEM, TEM and TG. Notably, this method was entirely different from the traditional means used for preparing other zinc phosphonate. Moreover, it could be deduced that ZnPS-PVPP possessed the potential applications for catalyst supports. In the initial catalytic tests, the catalysts immobilized onto ZnPS-PVPP showed comparable or higher activity and enantioselectivity with that of catalysts reported by our group in the asymmetric epoxidation of unfunctional olefins. - Graphical Abstract: Zinc poly(styrene-phenylvinylphosphonate)-phosphate was a novel type of layered crystalline organic polymer-inorganic hybrid material prepared under mild conditions without addition of any template and could be used as heterogeneous catalyst supports. Highlights: > New types of layered crystalline inorganic-organic polymer hybrid materials zinc poly(styrene-phenylvinylphosphonate-phosphate(ZnPS-PVPP)). > ZnPS-PVPP prepared under mild condition without adding of any template. > Immobilized chiral salen Mn (III) catalysts on ZnPS-PVPP supports show comparative activity and enantioselectivity with that of on ZSPP or ZPS-PVPA.

  16. Solubilization of insoluble inorganic phosphate by Burkholderia cepacia DA23 isolated from cultivated soil

    PubMed Central

    Song, Ok-Ryul; Lee, Seung-Jin; Lee, Yong-Seok; Lee, Sang-Cheol; Kim, Keun-Ki; Choi, Yong-Lark

    2008-01-01

    A mineral phosphate solubilizing bacterium, Burkholderia cepacia DA23 has been isolated from cultivated soils. Phosphate-solubilizing activities of the strain against three types of insoluble phosphate were quantitatively determined. When 3% of glucose concentration was used for carbon source, the strain had a marked mineral phosphate-solubilizing activity. Mineral phosphate solubilization was directly related to the pH drop by the strain. Analysis of the culture medium by high pressure liquid chromatography identified gluconic acid as the main organic acid released by Burkholderia cepacia DA23. Gluconic acid production was apparently the result of the glucose dehydrogenase activity and glucose dehydrogenase was affected by phosphate regulation. PMID:24031195

  17. A systematic genetic screen for genes involved in sensing inorganic phosphate availability in Saccharomyces cerevisiae

    DOE PAGES

    Choi, Joonhyuk; Rajagopal, Abbhirami; Xu, Yi -Fan; ...

    2017-05-17

    Saccharomyces cerevisiae responds to changes in extracellular inorganic phosphate (Pi) availability by regulating the activity of the phosphate-responsive (PHO) signaling pathway, enabling cells to maintain intracellular levels of the essential nutrient Pi. Pi-limitation induces upregulation of inositol heptakisphosphate (IP7) synthesized by the inositol hexakisphosphate kinase Vip1, triggering inhibition of the Pho80/Pho85 cyclin-cyclin dependent kinase (CDK) complex by the CDK inhibitor Pho81, which upregulates the PHO regulon through the CDK target and transcription factor Pho4. To identify genes that are involved in signaling upstream of the Pho80/Pho85/Pho81 complex and how they interact with each other to regulate the PHO pathway, wemore » performed genome-wide screens with the synthetic genetic array method. We identified more than 300 mutants with defects in signaling upstream of the Pho80/Pho85/Pho81 complex, including AAH1, which encodes an adenine deaminase that negatively regulates the PHO pathway in a Vip1-dependent manner. Moreover, we showed that even in the absence of VIP1, the PHO pathway can be activated under prolonged periods of Pi starvation, suggesting complexity in the mechanisms by which the PHO pathway is regulated.« less

  18. Inorganic phosphate blocks binding of pre-miRNA to Dicer-2 via its PAZ domain

    PubMed Central

    Fukunaga, Ryuya; Colpan, Cansu; Han, Bo W; Zamore, Phillip D

    2014-01-01

    In Drosophila, Dicer-1 produces microRNAs (miRNAs) from pre-miRNAs, whereas Dicer-2 generates small interfering RNAs from long double-stranded RNA (dsRNA), a process that requires ATP hydrolysis. We previously showed that inorganic phosphate inhibits Dicer-2 cleavage of pre-miRNAs, but not long dsRNAs. Here, we report that phosphate-dependent substrate discrimination by Dicer-2 reflects dsRNA substrate length. Efficient processing by Dicer-2 of short dsRNA requires a 5′ terminal phosphate and a two-nucleotide, 3′ overhang, but does not require ATP. Phosphate inhibits cleavage of such short substrates. In contrast, cleavage of longer dsRNA requires ATP but no specific end structure: phosphate does not inhibit cleavage of these substrates. Mutation of a pair of conserved arginine residues in the Dicer-2 PAZ domain blocked cleavage of short, but not long, dsRNA. We propose that inorganic phosphate occupies a PAZ domain pocket required to bind the 5′ terminal phosphate of short substrates, blocking their use and restricting pre-miRNA processing in flies to Dicer-1. Our study helps explain how a small molecule can alter the substrate specificity of a nucleic acid processing enzyme. PMID:24488111

  19. On the effect of the injection of potassium phosphate in vivo inducing the precipitation of serum calcium with inorganic phosphate

    PubMed Central

    Soares, Alcimar B; Ticianeli, José G; Soares, Letícia B M; Amaro, George

    2013-01-01

    High concentrations of inorganic phosphate (Pi) resulted from the hydrolysis of ATP is strongly associated to the weakness of the contractile mechanism of muscles due to its attractiveness to calcium. The majority of the experiments to study such effect are conducted in vitro. This work investigates the effects of different concentrations of Pi, induced by the injection of potassium phosphate in live animals, in the precipitation with serum calcium and the generation of calcium phosphate composites. The experiments were also designed to find out the ideal amount of potassium phosphate to induce an effective reaction. Potassium phosphate was injected in Wistar rats, randomly separated and distributed into seven groups. Group I was injected with 0.5 ml of saline solution (control) and groups II through VII were injected with 0.5, 1.5, 2.5, 5.0, 7.5 and 10.0 mg/kg of potassium phosphate, respectively. Blood collected from the inferior vena cava was submitted to biochemical analyses to measure the concentrations of calcium, Pi, urea and creatinine. The results showed that Pi, induced by the injection of potassium phosphate in live animals, causes precipitation with serum calcium, with statistically significant differences between the control and the treatment groups for doses up to 5.0 mg/kg. No statistically significant differences were found between the different doses and the concentration of urea and creatinine in the plasma. We conclude that potassium phosphate can be used to induce serum calcium precipitation in-vivo, with minor effects on other physiological variables, and the ideal dose to do so is 5.0 mg/kg. PMID:24379908

  20. Identification of Phosphorylation Sites Altering Pollen Soluble Inorganic Pyrophosphatase Activity.

    PubMed

    Eaves, Deborah J; Haque, Tamanna; Tudor, Richard L; Barron, Yoshimi; Zampronio, Cleidiane G; Cotton, Nicholas P J; de Graaf, Barend H J; White, Scott A; Cooper, Helen J; Franklin, F Christopher H; Harper, Jeffery F; Franklin-Tong, Vernonica E

    2017-03-01

    Protein phosphorylation regulates numerous cellular processes. Identifying the substrates and protein kinases involved is vital to understand how these important posttranslational modifications modulate biological function in eukaryotic cells. Pyrophosphatases catalyze the hydrolysis of inorganic phosphate (PPi) to inorganic phosphate Pi, driving biosynthetic reactions; they are essential for low cytosolic inorganic phosphate. It was suggested recently that posttranslational regulation of Family I soluble inorganic pyrophosphatases (sPPases) may affect their activity. We previously demonstrated that two pollen-expressed sPPases, Pr-p26.1a and Pr-p26.1b, from the flowering plant Papaver rhoeas were inhibited by phosphorylation. Despite the potential significance, there is a paucity of data on sPPase phosphorylation and regulation. Here, we used liquid chromatographic tandem mass spectrometry to map phosphorylation sites to the otherwise divergent amino-terminal extensions on these pollen sPPases. Despite the absence of reports in the literature on mapping phosphorylation sites on sPPases, a database survey of various proteomes identified a number of examples, suggesting that phosphorylation may be a more widely used mechanism to regulate these enzymes. Phosphomimetic mutants of Pr-p26.1a/b significantly and differentially reduced PPase activities by up to 2.5-fold at pH 6.8 and 52% in the presence of Ca(2+) and hydrogen peroxide over unmodified proteins. This indicates that phosphoregulation of key sites can inhibit the catalytic responsiveness of these proteins in concert with key intracellular events. As sPPases are essential for many metabolic pathways in eukaryotic cells, our findings identify the phosphorylation of sPPases as a potential master regulatory mechanism that could be used to attenuate metabolism.

  1. Microquantification of inorganic and organic phosphate by negative ion electrospray tandem mass spectrometry.

    PubMed

    Safian, Muhd F; Lehmann, Wolf D

    2015-04-01

    A new method for inorganic phosphate microquantification is introduced based on negative ion electrospray tandem mass spectrometry and stable isotope dilution by (18)O4-labeled phosphate. Quantification is performed using the non-labeled and (18)O3-labeled [P(18)O3](-) fragment ions at m/z 79 and 85, respectively, formed by dissociation of the [H2PO4](-) ion at m/z 97 and 105, respectively, visible in negative ion electrospray ionization mass spectrometry (ESI-MS) spectra. Tandem mass spectrometry was selected to remove an overlap with the isobaric [HSO4](-) ion at m/z 97 of sulfate and to establish an optimal sensitivity of the quantification assay. It is demonstrated that the assay can also measure the sum of inorganic and phosphoryl phosphate by prior enzymatic hydrolysis of phosphoryl phosphate. The assay works with phosphate concentrations in the micromolar range and, in combination with nano-ESI, is capable to quantitate absolute amounts of phosphate in the low nanogram range from complex samples.

  2. The effects of inorganic phosphate and arsenate on both passive muscle visco-elasticity and maximum Ca2+ activated tension in chemically skinned rat fast and slow twitch muscle fibres.

    PubMed

    Mutungi, Gabriel

    2003-01-01

    The effects of adding either 25 mM inorganic phosphate (Pi) or its structural analogue arsenate (ASi) on both the maximum Ca2+ activated tension (Po) and passive muscle visco-elasticity (P2 tension) were investigated at 10 degrees C, using segments of single, chemically skinned rat muscle fibres. Whilst the results confirmed some previous findings on the effects of Pi on Po, they also showed that the addition of 25 mM ASi led to a large (approximately 50%) but completely reversible depression of Po in both the fast and slow twitch rat muscle fibres. Moreover, the depression of Po by ASi was greater at low than at high pH values. Examined in the presence of Dextran T-500, the passive tension and sarcomere length responses to a ramp stretch were found to be qualitatively and quantitatively similar to those previously reported in intact rat muscle fibres. Thus, the tension response to a ramp stretch, in the presence and absence of either 25 mM Pi or ASi, consisted of a viscous (P1), a visco-elastic (P2) and an elastic (P3) tension. However, the addition of either 25 mM Pi or ASi led to approximately 15-18% increase in the amplitude of the visco-elastic (P2) tension but had little or no effect on the amplitudes of the other two tension components (viscous, P1 and elastic, P3 tensions). Furthermore, neither compound significantly altered the relaxation rate of the passive muscle visco-elasticity (P2 tension). These results show that Po (arising from cycling cross-bridges) and passive muscle visco-elasticity (P2 tension) are affected differently by both Pi and ASi and suggest that they may not share a common structural basis. The possibility that passive muscle visco-elasticity (P2 tension) arises from the gap-(titin) filament (as suggested previously by Mutungi and Ranatunga, 1996b J Physiol 496: 827-837) and that Pi and ASi increase its amplitude by interacting with the PEVK region of the filament are discussed.

  3. The effects of inorganic phosphate and creatine phosphate on force production in skinned muscles from rat ventricle.

    PubMed Central

    Kentish, J C

    1986-01-01

    Thin ventricular trabeculae from rat hearts were skinned with the non-ionic detergent Triton X-100. The isometric force development of these muscles was investigated over a range of Ca2+ concentrations (0.2-200 microM) in the presence of various concentrations of creatine phosphate (CP), creatine and inorganic phosphate (Pi). The addition of Pi (1-30 microM) at constant ionic strength reduced the maximum Ca2+-regulated force (obtained at 200 microM-Ca2+). At 20 mM-Pi force was 31 +/- 5% (mean +/- S.E. of mean, n = 7) of that in Pi-free solution. This inhibitory action of Pi was not due to an inhibition of creatine kinase activity or to a reduction in the amount of free energy available for work from ATP hydrolysis. Increases in Pi concentration over the range 0-20 mM shifted the sigmoid relationship between force and [Ca2+] to higher Ca2+ concentrations. The [Ca2+] required for 50% activation rose from 8.3 +/- 1.5 microM (mean +/- S.E. of mean, n = 7) in Pi-free solutions to 19.8 +/- 4.2 microM in 20 mM-Pi. An increase in CP concentration in the range 10-30 mM had a small inhibitory effect on maximum Ca2+-regulated force but did not alter the force--[Ca2+] relationship. Creatine (0-30 mM) was without effect on the skinned muscles. The inhibitory effects of Pi suggest that a net hydrolysis of CP to Pi and creatine in the myoplasm of intact cardiac cells could reduce force development at a given myoplasmic [Ca2+], especially if the latter was below the level needed to fully activate the myofibrils. This suggestion is discussed in relation to the CP hydrolysis and decrease in force development that are observed in cardiac muscle during hypoxia or ischaemia. PMID:3958986

  4. Availability of phosphorus from selected inorganic phosphate to juvenile abalone, Haliotis discus hannai ino.

    NASA Astrophysics Data System (ADS)

    Tan, Bei-Ping; Mai, Kang-Sen; Xu, Wei

    2002-06-01

    The availability of phosphorus to juvenile abalone, Haliotis discus hannai from primary, secondary and tertiary calcium phosphate, primary sodium or potassium phosphate separately or in combination was determined in a 120-day feeding trial. Seven semi-purified diets were formulated to contain relatively constant dietary phosphorus, ranging from 0.78% 0.82%. The concentrations of dietary phosphorus were presumed to be slightly below the requirement for abalone. A brown alga, Laminaria japonica, was used as a control diet. Abalone juveniles of silimar size (average weight 1.18 g; average shell length 18.74 mm) were distributed in a single-pass, flow-through system using a completely randomized design with eight treatments and three replicates each treatment. The survival ranged from 71.1% to 81.1%, and was not significantly (P>0.05) related to dietary treatment. However, the weight gain rate (41.72% 65.02%), daily increment in shell length (36.87 55.07 μm) and muscle RNA-DNA ratio (3.44 4.69) were significantly (P<0.05) affected by dietary treatment. Soft body alkaline phosphatase activity (10.9 19.8 U/g wet tissue) and carcass levels of lipid (7.71% 9.33%) and protein (46.68% 49.35%) were significantly (P<0.05) responsive to available phosphorus of the diets. Dietary treatment had significant effect (P<0.05) on concentrations of phosphorus in the whole body (WB) and soft body (SB). Apparent digestibility coefficients (45% 97%) of phosphorus were also significantly (P<0.05) different between dietary treatments. The results indicated that among these inorganic compounds, primary calcium, potassium and sodium phosphates separately or in combination could be utilized effectively by juvenile abalone as dietary phosphorus sources (availability ranging from 87% 97%). However, secondary and tertiary calcium phosphates were found to be low in availability, the values being 45% and 77%, repectively.

  5. Physiological and comparative proteome analyses reveal low-phosphate tolerance and enhanced photosynthesis in a maize mutant owing to reinforced inorganic phosphate recycling.

    PubMed

    Zhang, Kewei; Liu, Hanhan; Song, Jiuling; Wu, Wei; Li, Kunpeng; Zhang, Juren

    2016-06-08

    The low-phosphate-tolerant maize mutant Qi319-96 was obtained from Qi319 through cellular engineering. To elucidate the molecular mechanisms underlying the low-phosphate tolerance of this mutant, we performed comparative proteome analyses of the leaves of Qi319-96 and Qi319 under inorganic phosphate (Pi)-sufficient and Pi-deficient conditions. Low-phosphorus levels limit plant growth and metabolism. Although the overall phosphorus contents of shoots were not significantly different between Qi319 and Qi319-96, the Pi level of Qi319-96 was 52.94 % higher than that of Qi319. Under low phosphorus conditions, Qi319-96 had increased chlorophyll levels and enhanced photosynthesis. The changes in starch and sucrose contents under these conditions also differed between genotypes. The proteomic changes included 29 (Pi-sufficient) and 71 (Pi-deficient) differentially expressed proteins involved in numerous metabolic processes. Proteome and physiological analyses revealed that Qi319-96 could better remodel the lipid composition of membranes and had higher V-ATPase activity levels than Qi319 under low-phosphate starvation, which enhanced the recycling of intracellular Pi, as reflected by its increased Pi levels. Chlorophyll biosynthesis was improved and the levels, and activities, of several Calvin cycle and "CO2 pump" enzymes were greater in Qi319-96 than in Qi319, which led to a higher rate of photosynthesis under low-phosphate stress in this line compared with in Qi319. Our results suggest that the increased tolerance of the maize mutant Qi319-96 to low-phosphate levels is owing to its ability to increase Pi availability. Additionally, inbred lines of maize with low-P-tolerant traits could be obtained effectively through cellular engineering.

  6. A precise method for the analysis of d18O of dissolved inorganic phosphate in seawater

    USGS Publications Warehouse

    McLaughlin, K.; Silva, S.; Kendall, C.; Stuart-Williams, Hilary; Paytan, A.

    2004-01-01

    A method for preparation and analysis of the oxygen isotope composition (d18O) of dissolved inorganic phosphate (DIP) has been developed and preliminary results for water samples from various locations are reported. Phosphate is extracted from seawater samples by coprecipitation with magnesium hydroxide. Phosphate is further purified through a series of precipitations and resin separation and is ultimately converted to silver phosphate. Silver phosphate samples are pyrolitically decomposed to carbon monoxide and analyzed for d18O. Silver phosphate samples weighing 0.7 mg (3.5 mol oxygen) can be analyzed routinely with an average standard deviation of about 0.3. There is no isotope fractionation during extraction and blanks are negligible within analytical error. Reproducibility was determined for both laboratory standards and natural samples by multiple analyses. A comparison between filtered and unfiltered natural seawater samples was also conducted and no appreciable difference was observed for the samples tested. The d18O values of DIP in seawater determined using this method range from 18.6 to 22.3, suggesting small but detectable natural variability in seawater. For the San Francisco Bay estuary DIP d18O is more variable, ranging from 11.4 near the San Joaquin River to 20.1 near the Golden Gate Bridge, and was well correlated with salinity, phosphate concentration, and d18O of water.

  7. Controlled formation of calcium-phosphate-based hybrid mesocrystals by organic-inorganic co-assembly.

    PubMed

    Zhai, Halei; Chu, Xiaobin; Li, Li; Xu, Xurong; Tang, Ruikang

    2010-11-01

    An understanding of controlled formation of biomimetic mesocrystals is of great importance in materials chemistry and engineering. Here we report that organic-inorganic hybrid plates and even mesocrystals can be conveniently synthesized using a one-pot reaction in a mixed system of protein (bovine serum albumin (BSA)), surfactant (sodium bis(2-ethylhexyl) sulfosuccinate (AOT)) and supersaturated calcium phosphate solution. The morphologies of calcium-phosphate-based products are analogous to the general inorganic crystals but they have abnormal and interesting substructures. The hybrids are constructed by the alternate stacking of organic layer (thickness of 1.31 nm) and well-crystallized inorganic mineral layer (thickness of 2.13 nm) at the nanoscale. Their morphologies (spindle, rhomboid and round) and sizes (200 nm-2 μm) can be tuned gradually by changing BSA, AOT and calcium phosphate concentrations. This modulation effect can be explained by a competition between the anisotropic and isotropic assembly of the ultrathin plate-like units. The anisotropic assembly confers mesocrystal characteristics on the hybrids while the round ones are the results of isotropic assembly. However, the basic lamellar organic-inorganic substructure remains unchanged during the hybrid formation, which is a key factor to ensure the self-assembly from molecule to micrometre scale. A morphological ternary diagram of BSA-AOT-calcium phosphate is used to describe this controlled formation process, providing a feasible strategy to prepare the required materials. This study highlights the cooperative effect of macromolecule (frame structure), small biomolecule (binding sites) and mineral phase (main component) on the generation and regulation of biomimetic hybrid mesocrystals.

  8. Controlled formation of calcium-phosphate-based hybrid mesocrystals by organic-inorganic co-assembly

    NASA Astrophysics Data System (ADS)

    Zhai, Halei; Chu, Xiaobin; Li, Li; Xu, Xurong; Tang, Ruikang

    2010-11-01

    An understanding of controlled formation of biomimetic mesocrystals is of great importance in materials chemistry and engineering. Here we report that organic-inorganic hybrid plates and even mesocrystals can be conveniently synthesized using a one-pot reaction in a mixed system of protein (bovine serum albumin (BSA)), surfactant (sodium bis(2-ethylhexyl) sulfosuccinate (AOT)) and supersaturated calcium phosphate solution. The morphologies of calcium-phosphate-based products are analogous to the general inorganic crystals but they have abnormal and interesting substructures. The hybrids are constructed by the alternate stacking of organic layer (thickness of 1.31 nm) and well-crystallized inorganic mineral layer (thickness of 2.13 nm) at the nanoscale. Their morphologies (spindle, rhomboid and round) and sizes (200 nm-2 μm) can be tuned gradually by changing BSA, AOT and calcium phosphate concentrations. This modulation effect can be explained by a competition between the anisotropic and isotropic assembly of the ultrathin plate-like units. The anisotropic assembly confers mesocrystal characteristics on the hybrids while the round ones are the results of isotropic assembly. However, the basic lamellar organic-inorganic substructure remains unchanged during the hybrid formation, which is a key factor to ensure the self-assembly from molecule to micrometre scale. A morphological ternary diagram of BSA-AOT-calcium phosphate is used to describe this controlled formation process, providing a feasible strategy to prepare the required materials. This study highlights the cooperative effect of macromolecule (frame structure), small biomolecule (binding sites) and mineral phase (main component) on the generation and regulation of biomimetic hybrid mesocrystals.

  9. Supplementation of inorganic phosphate enhancing the removal efficiency of tannery sludge-borne Cr through bioleaching.

    PubMed

    Zheng, Guanyu; Zhou, Lixiang

    2011-10-15

    Four inorganic mineral nutrients including NH4+, K+, Mg2+ and soluble inorganic phosphate (Pi) were investigated to reveal the potential limiting nutrients for tannery sludge bioleaching process driven by Acidithiobacillus species, and the feasibility of supplementing the limiting nutrients to accelerate tannery sludge bioleaching was studied in the present study. It was found that the concentration of Pi was lower than 3.5 mg/L throughout the whole bioleaching process, which is the most probable restricting nutrient for tannery sludge bioleaching. Further experiments revealed that the deficiency of Pi could seriously influence the growth of Acidithiobacillus thiooxidans and lower its oxidization capacity for S0, and the limiting concentration of Pi for the growth of A. thiooxidans was 6 mg/L. The low concentration of soluble Pi in sludge matrix was resulted from the extremely strong sorbing/binding capacity of tannery sludge for phosphate. The supplementation of more than 1.6 g/L KH2PO4 into tannery sludge bioleaching system could effectively stimulate the growth of Acidithiobacillus species, enhance Cr removal rate and further shorten tannery sludge bioleaching period from 10 days to 7 days. Therefore, inorganic phosphate supplementation is an effective and feasible method to accelerate tannery sludge bioleaching process, and the optimum dosage of KH2PO4 was 1.6 g/L for tannery sludge with 5.1% of total solids.

  10. Heat Stress Affects Pi-related Genes Expression and Inorganic Phosphate Deposition/Accumulation in Barley

    PubMed Central

    Pacak, Andrzej; Barciszewska-Pacak, Maria; Swida-Barteczka, Aleksandra; Kruszka, Katarzyna; Sega, Pawel; Milanowska, Kaja; Jakobsen, Iver; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2016-01-01

    Phosphorus (P) in plants is taken from soil as an inorganic phosphate (Pi) and is one of the most important macroelements in growth and development. Plants actively react to Pi starvation by the induced expression of Pi transporters, MIR399, MIR827, and miR399 molecular sponge – IPS1 genes and by the decreased expression of the ubiquitin-conjugating enzyme E2 (PHOSPHATE2 – PHO2) and Pi sensing and transport SPX-MFS genes. The PHO2 protein is involved in the degradation of Pi transporters PHT1;1 (from soil to roots) and PHO1 (from roots to shoots). The decreased expression of PHO2 leads to Pi accumulation in shoots. In contrast, the pho1 mutant shows a decreased level of Pi concentration in shoots. Finally, Pi starvation leads to decreased Pi concentration in all plant tissues. Little is known about plant Pi homeostasis in other abiotic stress conditions. We found that, during the first hour of heat stress, Pi accumulated in barley shoots but not in the roots, and transcriptomic data analysis as well as RT-qPCR led us to propose an explanation for this phenomenon. Pi transport inhibition from soil to roots is balanced by lower Pi efflux from roots to shoots directed by the PHO1 transporter. In shoots, the PHO2 mRNA level is decreased, leading to an increased Pi level. We concluded that Pi homeostasis in barley during heat stress is maintained by dynamic changes in Pi-related genes expression. PMID:27446155

  11. Heat Stress Affects Pi-related Genes Expression and Inorganic Phosphate Deposition/Accumulation in Barley.

    PubMed

    Pacak, Andrzej; Barciszewska-Pacak, Maria; Swida-Barteczka, Aleksandra; Kruszka, Katarzyna; Sega, Pawel; Milanowska, Kaja; Jakobsen, Iver; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2016-01-01

    Phosphorus (P) in plants is taken from soil as an inorganic phosphate (Pi) and is one of the most important macroelements in growth and development. Plants actively react to Pi starvation by the induced expression of Pi transporters, MIR399, MIR827, and miR399 molecular sponge - IPS1 genes and by the decreased expression of the ubiquitin-conjugating enzyme E2 (PHOSPHATE2 - PHO2) and Pi sensing and transport SPX-MFS genes. The PHO2 protein is involved in the degradation of Pi transporters PHT1;1 (from soil to roots) and PHO1 (from roots to shoots). The decreased expression of PHO2 leads to Pi accumulation in shoots. In contrast, the pho1 mutant shows a decreased level of Pi concentration in shoots. Finally, Pi starvation leads to decreased Pi concentration in all plant tissues. Little is known about plant Pi homeostasis in other abiotic stress conditions. We found that, during the first hour of heat stress, Pi accumulated in barley shoots but not in the roots, and transcriptomic data analysis as well as RT-qPCR led us to propose an explanation for this phenomenon. Pi transport inhibition from soil to roots is balanced by lower Pi efflux from roots to shoots directed by the PHO1 transporter. In shoots, the PHO2 mRNA level is decreased, leading to an increased Pi level. We concluded that Pi homeostasis in barley during heat stress is maintained by dynamic changes in Pi-related genes expression.

  12. H(+)-dependent inorganic phosphate uptake in Trypanosoma brucei is influenced by myo-inositol transporter.

    PubMed

    Russo-Abrahão, Thais; Koeller, Carolina Macedo; Steinmann, Michael E; Silva-Rito, Stephanie; Marins-Lucena, Thaissa; Alves-Bezerra, Michele; Lima-Giarola, Naira Ligia; de-Paula, Iron Francisco; Gonzalez-Salgado, Amaia; Sigel, Erwin; Bütikofer, Peter; Gondim, Katia Calp; Heise, Norton; Meyer-Fernandes, José Roberto

    2017-04-01

    Trypanosoma brucei is an extracellular protozoan parasite that causes human African trypanosomiasis or "sleeping sickness". During the different phases of its life cycle, T. brucei depends on exogenous inorganic phosphate (Pi), but little is known about the transport of Pi in this organism. In the present study, we showed that the transport of (32)Pi across the plasma membrane follows Michaelis-Menten kinetics and is modulated by pH variation, with higher activity at acidic pH. Bloodstream forms presented lower Pi transport in comparison to procyclic forms, that displayed an apparent K0.5 = 0.093 ± 0.008 mM. Additionally, FCCP (H(+)-ionophore), valinomycin (K(+)-ionophore) and SCH28080 (H(+), K(+)-ATPase inhibitor) inhibited the Pi transport. Gene Tb11.02.3020, previously described to encode the parasite H(+):myo-inositol transporter (TbHMIT), was hypothesized to be potentially involved in the H(+):Pi cotransport because of its similarity with the Pho84 transporter described in S. cerevisiae and other trypanosomatids. Indeed, the RNAi mediated knockdown remarkably reduced TbHMIT gene expression, compromised cell growth and decreased Pi transport by half. In addition, Pi transport was inhibited when parasites were incubated in the presence of concentrations of myo-inositol that are above 300 μM. However, when expressed in Xenopus laevis oocytes, two-electrode voltage clamp experiments provided direct electrophysiological evidence that the protein encoded by TbHMIT is definitely a myo-inositol transporter that may be only marginally affected by the presence of Pi. These results confirmed the presence of a Pi carrier in T. brucei, similar to the H(+)-dependent inorganic phosphate system described in S. cerevisiae and other trypanosomatids. This transport system contributes to the acquisition of Pi and may be involved in the growth and survival of procyclic forms. In summary, this work presents the first description of a Pi transport system in T. brucei.

  13. Uptake of inorganic phosphate is a limiting factor for Saccharomyces cerevisiae during growth at low temperatures.

    PubMed

    Vicent, Isabel; Navarro, Alfonso; Mulet, Jose M; Sharma, Sukesh; Serrano, Ramón

    2015-05-01

    The fermenting ability of Saccharomyces at low temperatures is crucial for the development of alcoholic beverages, but the key factors for the cold tolerance of yeast are not well known. In this report, we present the results of a screening for genes able to confer cold tolerance by overexpression in a laboratory yeast strain auxotrophic for tryptophan. We identified genes of tryptophan permeases (TAT1 and TAT2), suggesting that the first limiting factor in the growth of tryptophan auxotrophic yeast at low temperatures is tryptophan uptake. This fact is of little relevance to industrial strains which are prototrophic for tryptophan. Then, we screened for genes able to confer growth at low temperatures in tryptophan-rich media and found several genes related to phosphate uptake (PHO84, PHO87, PHO90 and GTR1). This suggests that without tryptophan limitation, uptake of inorganic phosphate becomes the limiting factor. We have found that overexpression of the previously uncharacterized ORF YCR015c/CTO1 increases the uptake of inorganic phosphate. Also, genes involved in ergosterol biosynthesis (NSG2) cause improvement of growth at 10°C, dependent on tryptophan uptake, while the gluconeogenesis gene PCK1 and the proline biosynthesis gene PRO2 cause an improvement in growth at 10°C, independent of tryptophan and phosphate uptake. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  14. Inorganic phosphate (Pi) modulates the expression of key regulatory proteins of the inorganic pyrophosphate (PPi) metabolism in TGF-β1-stimulated chondrocytes.

    PubMed

    Hamade, Tala; Bianchi, Arnaud; Sebillaud, Sylvie; Netter, Patrick; Jouzeau, Jean-Yves; Cailotto, Frédéric

    2010-01-01

    The balance between extracellular inorganic phosphate (ePi) and extracellular inorganic pyrophosphate (ePPi) is controlled by four membrane proteins: the transporters ANK (exporting PPi outside the cells) and PiT-1 (importing ePi into the cells), and the enzymes PC-1 (generating ePPi from nucleotides) and Tissue Non-specific Alkaline Phosphatase (TNAP, hydrolyzing ePPi into ePi). TGF-β1 was shown to stimulate ANK and PC-1 expression in articular chondrocytes, and subsequent ePPi level, as well as to increase ePi uptake by inducing PiT-1 expression in a chondrogenic cell line. Thus, we investigated the ability of ePi to modulate the effect of TGF-β1 on the regulatory proteins of the ePi/ePPi balance in chondrocytes. In the pathophysiological range of 0.01-1 mM, ePi was inactive by itself but potentiated the stimulatory effects of TGF-β1 on ANK, PC-1 or PiT-1 mRNA (RT-qPCR) and protein (Western blot) levels. PC-1 activity was also increased by TGF-β1 and further potentiated by ePi supplementation. TNAP mRNA and activity became undetectable in response to TGF-β1. These data suggest that ePi could increase ePPi level by changing the control of ANK and PC-1 expression by TGF-β1, further highlighting an adaptative regulation of the Pi/PPi balance to prevent basic calcium phosphate deposition into the joints.

  15. Inorganic phosphate accumulation and cadmium detoxification in Klebsiella aerogenes NCTC 418 growing in continuous culture

    SciTech Connect

    Aiking, H.; Stijnman, A.; van Garderen, C.; van Heerikhuizen, H.; van Riet, J.

    1984-02-01

    Klebsiella aerogenes NCTC-418, growing in the presence of cadmium under glucose-, sulfate-, or phosphate-limited conditions in continuous culture, exhibits two different cadmium detoxifying mechanisms. In addition to sulfide formation, increased accumulation of P/sub i/ is demonstrated as a novel mechanism. Intracellular cadmium is always quantitatively counterbalanced by a concerted increase in both inorganic sulfide and P/sub i/ contents of the cells. This led to the conclusion that production of sulfide and accumulation of P/sub i/ are detoxification mechanisms present in K. aerogenes but that their relative importance is crucially dependent on the strain and the growth conditions employed.

  16. Colorimetric estimation of inorganic phosphate in colored and/or turbid biological samples: assay of phosphohydrolases.

    PubMed

    Upreti, G C

    1984-03-01

    A simple method of inorganic phosphate determination for colored and/or turbid biological samples is described. The procedure is mild, and so is suitable for routine phosphohydrolase assays. Following deproteinization by ice-cold trichloroacetic (or silicotungstic) acid, the sample was treated with acid-washed charcoal to remove interference due to color. The phosphate in the colorless supernatant was assayed either by measuring the phosphomolybdate spectrophotometrically at 310 nm, following its extraction in organic solvents or by a modified Fiske and Subbarow method. The turbidity interference in the latter case was eliminated either by centrifugation, by sodium dodecyl sulfate treatment, or by extraction of reduced phosphomolybdate blue color by cyclohexanone. Though deproteinization by silicotungstic acid eliminated the turbidity problem, its use in conjunction with charcoal treatment was not convenient.

  17. Evaluation of a low temperature hardening Inorganic Phosphate Cement for high-temperature applications

    SciTech Connect

    Alshaaer, M.; Cuypers, H.; Mosselmans, G.; Rahier, H.; Wastiels, J.

    2011-01-15

    Phase and mechanical changes of Inorganic Phosphate Cement (IPC) are identified along with changes in macro properties as functions of temperature and time. In addition to amorphous phases, the presence of significant amounts of brushite and wollastonite in the reference IPC is confirmed using X-ray diffraction. The thermal behavior of IPC up to 1000 {sup o}C shows that contraction of the solid phase in IPC due to chemical transformations causes reduction in the volume of the material. Also the ongoing meta-stable calcium phosphate transformations and reactions over a long time contribute significantly to the phase instability of the material at ambient conditions. It is found that the strength of IPC increases with ageing at ambient conditions but the formation microcracks below 105 {sup o}C causes a sharp reduction in the mechanical performance of IPC. According to the results obtained by Mercury intrusion porosimetry, the pore system of the reference IPC is dominated by mesopores.

  18. A kinetic study of the effects of phosphate and organic phosphates on the activity of phosphoenolpyruvate carboxylase from Crassula argentea.

    PubMed

    Meyer, C R; Rustin, P; Wedding, R T

    1989-05-15

    The effects of phosphate and several phosphate-containing compounds on the activity of purified phosphoenolpyruvate carboxylase (PEPC) from the crassulacean acid metabolism plant, Crassula argentea, were investigated. When assayed at subsaturating phosphoenolpyruvate (PEP) concentrations, low concentrations of most of the compounds tested were found to stimulate PEPC activity. This activation, variable in extent, was found in all cases to be competitive with glucose 6-phosphate (Glc-6-P) stimulation, suggesting that these effectors bind to the Glc-6-P site. At higher concentrations, depending upon the effector molecule studied, deactivation, inhibition, or no response was observed. More detailed studies were performed with Glc-6-P, AMP, phosphoglycolate, and phosphate. AMP had previously been shown to be a specific ligand for the Glc-6-P site. The main effect of Glc-6-P and AMP on the kinetic parameters was to decrease the apparent Km and increase Vmax/Km. AMP also caused a decrease in the Vmax of the reaction. In contrast, phosphoglycolate acted essentially as a competitive inhibitor increasing the apparent Km for PEP and decreasing Vmax/Km. Inorganic phosphate had a biphasic effect on the kinetic parameters, resulting in a transient decrease in Km followed by an increase of the apparent Km for PEP with increasing concentration of phosphate. The Vmax also was decreased with increasing phosphate concentrations. Further, the enzyme appeared to respond to the complex of phosphate with magnesium. In the presence of a saturating concentration of AMP, no activation but rather inhibition was observed with increasing phosphate concentration. This is consistent with the binding of phosphate to two separate sites--the Glc-6-P activation site and an inhibitory site, a phenomenon that may be occurring with other phosphate containing compounds. High concentrations of phosphate with magnesium were found to protect enzyme activity when PEPC, previously shown to contain an

  19. A universal small molecule, inorganic phosphate, restricts the substrate specificity of Dicer-2 in small RNA biogenesis

    PubMed Central

    Fukunaga, Ryuya; Zamore, Phillip D

    2014-01-01

    The enzyme Dicer is central to the production of small silencing RNAs such as microRNAs (miRNAs) and small interfering RNAs (siRNAs). Like other insects, Drosophila melanogaster uses different Dicers to make siRNAs and miRNAs: Dicer-1 produces miRNAs from pre-miRNAs, whereas Dicer-2 generates siRNAs from long double-stranded RNA (dsRNA). How do the 2 Dicers achieve their substrate specificity? Here, we review recent findings that inorganic phosphate restricts the substrate specificity of Dicer-2 to long dsRNA. Inorganic phosphate inhibits Dicer-2 from binding and cleaving pre-miRNAs, without affecting the processing of long dsRNA. Crystal structures of a fragment of human Dicer in complex with an RNA duplex identify a phosphate-binding pocket that recognizes both the 5′-monophosphate of a substrate RNA and inorganic phosphate. We propose that inorganic phosphate occupies the phosphate-binding pocket in the fly Dicer-2, blocking binding of pre-miRNA and restricting pre-miRNA processing to Dicer-1. Thus, a small molecule can alter the substrate specificity of a nucleic acid-processing enzyme. PMID:24787225

  20. Interstitial Inorganic Phosphate as a Tumor Microenvironment Marker for Tumor Progression

    PubMed Central

    Bobko, Andrey A.; Eubank, Timothy D.; Driesschaert, Benoit; Dhimitruka, Ilirian; Evans, Jason; Mohammad, Rahman; Tchekneva, Elena E.; Dikov, Mikhail M.; Khramtsov, Valery V.

    2017-01-01

    Noninvasive in vivo assessment of chemical tumor microenvironment (TME) parameters such as oxygen (pO2), extracellular acidosis (pHe), and concentration of interstitial inorganic phosphate (Pi) may provide unique insights into biological processes in solid tumors. In this work, we employ a recently developed multifunctional trityl paramagnetic probe and electron paramagnetic resonance (EPR) technique for in vivo concurrent assessment of these TME parameters in various mouse models of cancer. While the data support the existence of hypoxic and acidic regions in TME, the most dramatic differences, about 2-fold higher concentrations in tumors vs. normal tissues, were observed for interstitial Pi - the only parameter that also allowed for discrimination between non-metastatic and highly metastatic tumors. Correlation analysis between [Pi], pO2, pHe and tumor volumes reveal an association of high [Pi] with changes in tumor metabolism and supports different mechanisms of protons and Pi accumulation in TME. Our data identifies interstitial inorganic phosphate as a new TME marker for tumor progression. Pi association with tumor metabolism, buffer-mediated proton transport, and a requirement of high phosphorus content for the rapid growth in the “growth rate hypothesis” may underline its potential role in tumorigenesis and tumor progression. PMID:28117423

  1. Estimation of standardized phosphorus retention for inorganic phosphate sources in broilers.

    PubMed

    Liu, S B; Xie, J J; Lu, L; Li, S F; Zhang, L Y; Jiang, Y; Luo, X G

    2013-08-01

    Two experiments were conducted to estimate standardized P retention (SPR) values of dicalcium phosphate (DCP), monocalcium phosphate (MCP), and monopotassium phosphate (MKP) in broilers. In total, ninety-six 22-d-old male broilers with similar BW (780 g average) were used in each experiment. The chicks were randomly allotted to 1 of 4 treatments (P-free, DCP, MCP, or MKP diets) with 6 replicate cages of 4 chicks each in a completely randomized design. After 3-d acclimation, chicks were fasted for 24 h and then fed P-free, DCP, MCP, or MKP diets for 4 h in Exp. 1 or 72 h in Exp. 2. Excreta samples were collected for a total of 28 or 52 h (24 or 48 h after feed withdrawal) in Exp. 1 and 96 or 120 h (24 or 48 h after feed withdrawal) in Exp. 2, respectively. The excreta collection time of 52 h in Exp. 1 or 96 h in Exp. 2 was adequate for the estimation of SPR. The estimated basal endogenous P losses (EPL) in chicks fed the P-free diet were 109 ± 4 mg/52 h per bird and 49.2 ± 4.0 mg/96 h per bird in Exp. 1 and 2, respectively. The SPR values of inorganic phosphate sources corrected by the above basal EPL differed (P < 0.001) in Exp. 2 but not in Exp. 1. However, these SPR values were very similar between the 2 experiments with 68.7, 69.8, or 76.6% in Exp. 1 and 71.8, 70.6, or 78.3% in Exp. 2 for DCP, MCP, or MKP, respectively. The results from the current study indicated that, compared with the 72-h feeding and 96-h excreta collection procedure, the 4-h feeding and 52-h excreta collection procedure was a relatively quicker time- and labor-saving method for estimating the SPR values of inorganic P sources in broilers. The estimated SPR values of commonly used inorganic P sources (MCP and DCP) were about 70%.

  2. Utilization of titanium oxide-like compound as an inorganic phosphate adsorbent for the control of serum phosphate level in chronic renal failure.

    PubMed

    Tamagawa, Kazuhiko; Nakayama-Imaohji, Haruyuki; Wakimoto, Shin; Ichimura, Minoru; Kuwahara, Tomomi

    2010-08-01

    Hyperphosphatemia adversely affects the prognosis of patients with chronic renal failure (CRF). We synthesized a titanium oxide-like compound (TAP) as a phosphate adsorbent for treatment of hyperphosphatemia in CFR patients. We evaluated the ability of TAP to adsorb inorganic phosphate in vitro and in vivo. TAP was shown to contain sulfate and hydroxyl groups by thermal analysis, which probably involved in phosphate adsorption through an ionic exchange mechanism. TAP constantly adsorbed phosphate (66.20-72.84 mg/g TAP) over a wide pH range (1.22-7.27) in vitro. To evaluate the phosphate binding potential of TAP in vivo, adenine-induced CRF rats were fed AIN-76 diet containing 3% TAP, 10% TAP, 3% sevelamer hydrochloride (clinical phosphate adsorbent), or 3% calcium carbonate, and serum levels of phosphate and calcium and urinary phosphate were compared with those in untreated CRF rats. Orally administered TAP showed the inhibitory effect on serum phosphate level in adenine-induced CRF rats, which was equivalent to that of sevelamer hydrochloride. These results indicate that TAP is a useful alternative phosphate-binder with fewer side effects than sevelamer hydrochloride and calcium carbonate.

  3. Characterization of the interaction between chitosan and inorganic sodium phosphates by means of rheological and optical microscopy studies.

    PubMed

    Casettari, Luca; Cespi, Marco; Palmieri, Giovanni Filippo; Bonacucina, Giulia

    2013-01-16

    The physicochemical and rheological properties of chitosan and two different inorganic sodium phosphate dispersions (NaH(2)PO(4) and Na(3)PO(4)) were investigated in order to elucidate the role of different factors, such as ratios between polymer and sodium inorganic phosphates, different pHs and storage stability, on the gelling properties of chitosan. This was deemed opportune since physico-chemical characterizations of chitosan in the literature often appear incomplete and questionable. We also compared the elastic modulus values of the different chitosan/inorganic phosphate systems and examined their behaviour through optical microscopy analyses. The most efficient formulations that showed a thermogelling capacity with a significant gel transition behaviour after 24h were the NaH(2)PO(4)/chitosan and Na(3)PO(4)/chitosan systems at ratio 2 and pH 7.0. These results confirmed the importance of the pH value and ratio selection for the final systems.

  4. Enzyme activity in dialkyl phosphate ionic liquids

    SciTech Connect

    Thomas, M.F.; Dunn, J.; Li, L.-L.; Handley-Pendleton, J. M.; van der lelie, D.; Wishart, J. F.

    2011-12-01

    The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariellavolvacea were studied in the following ionic liquids, 1,3-dimethylimidazolium dimethyl phosphate, [mmim][dmp], 1-ethyl-3-methylimidazolium dimethyl phosphate, [emim][dmp], 1-ethyl-3-methylimidazolium diethyl phosphate, [emim][dep] and 1-ethyl-3-methylimidazolium acetate, [emim][OAc]. Activity was determined by analyzing the hydrolysis of para-nitrobenzene carbohydrate derivatives. In general, the enzymes were most active in the dimethyl phosphate ionic liquids, followed by acetate. Generally speaking, activity decreased sharply for concentrations of [emim][dep] above 10% v/v, while the other ionic liquids showed less impact on activity up to 20% v/v.

  5. Effects of inorganic phosphate on the light dependent thylakoid energization of intact spinach chloroplasts

    SciTech Connect

    Heineke, D.; Heldt, H.W. ); Stitt, M. )

    1989-09-01

    The light dependent energization of the thylakoid membrane was analyzed in isolated intact spinach (Spinacia oleracea L.) chloroplasts incubated with different concentrations of inorganic phosphate (Pi). Two independent methods were used: (a) the accumulation of ({sup 14}C)5,5-dimethyl-2,4-oxazolidinedione and ({sup 14}C)methylamine; (b) the energy dependent chlorophyll fluorescence quenching. The inhibition of CO{sub 2} fixation by superoptimal medium Pi or by adding glyceraldehyde - an inhibitor of the Calvin cycle - leads to an increased energization of the thylakoid membrane; however, the membrane energization decreases when chloroplasts are inhibited by suboptimal Pi. This specific low phosphate effect could be partially reversed by adding oxaloacetate, which regenerates the electron acceptor NADP{sup +} and stimulates linear electron transport. The energization seen in low Pi is, however, always lower than in superoptimal Pi, even in the presence of oxaloacetate. Energization recovers in the presence of low amounts of N,N{prime}-dicyclohexylcarbodiimide, which reacts with proton channels including the coupling factor 1 ATP synthase. N,N{prime}-Dicyclohexylcarbodiimide has no effect on energization of chloroplasts in superoptimal Pi. These results suggest there is a specific low phosphate proton leak in the thylakoids, and its origin is discussed.

  6. Factors Which Affect the Amount of Inorganic Phosphate, Phosphorylcholine, and Phosphorylethanolamine in Xylem Exudate of Tomato Plants 1

    PubMed Central

    Martin, Barry A.; Tolbert, N. E.

    1983-01-01

    Phosphate in the xylem exudate of tomato (Lycopersicon esculentum) plants was 70 to 98% inorganic phosphate (Pi), 2 to 30% P-choline, and less than 1% P-ethanolamine. Upon adding 32Pi to the nutrient, Pi in xylem exudate had the same specific activity within 4 hours. P-choline and P-ethanolamine reached the same specific activity only after 96 hours. The amount of Pi in xylem exudate was dependent on Pi concentration in the nutrient and decreased from 1700 to 170 micromolar when Pi in the nutrient decreased from 50 to 2 micromolar. The flux of 0.4 nmoles organic phosphate per minute per gram fresh weight root into the xylem exudate was not affected by the Pi concentration in the nutrient solution unless it was below 1 micromolar. During 7 days of Pi starvation, Pi in the xylem exudate decreased from 1400 to 130 micromolar while concentrations of the two phosphate esters remained unchanged. The concentration of phosphate esters in the xylem exudate was increased by addition of choline or ethanolamine to the nutrient solution, but Pi remained unchanged. Upon adding [14C]choline to the nutrient, 10 times more [14C]P-choline than [14C]choline was in the xylem exudate and 85 to 90% of the ester phosphate was P-choline. When [14C]ethanolamine was added, [14C]P-ethanolamine and [14C]ethanolamine in the xylem sap were equal in amount. P-choline and P-ethanolamine accumulated in leaves of whole plants at the same time and the same proportion as observed for their flux into the xylem exudate. No relationship between the transport of P-choline and Pi in the xylem was established. Rather, the amount of choline in xylem exudate and its incorporation into phosphatidylcholine in the leaf suggest that the root is a site of synthesis of P-choline and P-ethanolamine for phospholipid synthesis in tomato leaves. PMID:16663240

  7. Slc20a2 is critical for maintaining a physiologic inorganic phosphate level in cerebrospinal fluid.

    PubMed

    Jensen, Nina; Autzen, Jacob Kwasi; Pedersen, Lene

    2016-04-01

    Mutations in the SLC20A2-gene encoding the inorganic phosphate (Pi) transporter PiT2 can explain approximately 40% of the familial cases of the rare neurodegenerative disorder primary familial brain calcification (Fahr's disease). The disease characteristic, cerebrovascular-associated calcifications, is also present in Slc20a2-knockout (KO) mice. Little is known about the specific role(s) of PiT2 in the brain. Recent in vitro studies, however, suggest a role in regulation of the [Pi] in cerebrospinal fluid (CSF). We here show that Slc20a2-KO mice indeed have a high CSF [Pi] in agreement with a role of PiT2 in Pi export from the CSF. The implications in relation to disease mechanism are discussed.

  8. A simple method for tuning the glass transition process in inorganic phosphate glasses

    PubMed Central

    Fulchiron, René; Belyamani, Imane; Otaigbe, Joshua U.; Bounor-Legaré, Véronique

    2015-01-01

    The physical modification of glass transition temperature (Tg) and properties of materials via blending is a common practice in industry and academia and has a large economic advantage. In this context, simple production of hitherto unattainable new inorganic glass blends from already existing glass compositions via blending raises much hope with the potential to provide new glasses with new and improved properties, that cannot be achieved with classical glass synthesis, for a plethora of applications such as computers screens, glass-to-metal seals, and storage materials for nuclear wastes. Here, we demonstrate that blends of the specific glass compositions studied are miscible in all proportions, an unreported phenomenon in hard condensed matter like glass. Interestingly, excellent agreement was found between the obtained data and calculated Tgs from theoretical equations (Supplementary information) for predicting the composition dependence of Tg for miscible blends with weak but significant specific interactions between the blend components. That this blending method is at present not applied to inorganic glasses reflects the fact that water and chemically resistant phosphate glasses with relatively low Tgs have become available only recently. PMID:25666949

  9. A simple method for tuning the glass transition process in inorganic phosphate glasses

    NASA Astrophysics Data System (ADS)

    Fulchiron, René; Belyamani, Imane; Otaigbe, Joshua U.; Bounor-Legaré, Véronique

    2015-02-01

    The physical modification of glass transition temperature (Tg) and properties of materials via blending is a common practice in industry and academia and has a large economic advantage. In this context, simple production of hitherto unattainable new inorganic glass blends from already existing glass compositions via blending raises much hope with the potential to provide new glasses with new and improved properties, that cannot be achieved with classical glass synthesis, for a plethora of applications such as computers screens, glass-to-metal seals, and storage materials for nuclear wastes. Here, we demonstrate that blends of the specific glass compositions studied are miscible in all proportions, an unreported phenomenon in hard condensed matter like glass. Interestingly, excellent agreement was found between the obtained data and calculated Tgs from theoretical equations (Supplementary information) for predicting the composition dependence of Tg for miscible blends with weak but significant specific interactions between the blend components. That this blending method is at present not applied to inorganic glasses reflects the fact that water and chemically resistant phosphate glasses with relatively low Tgs have become available only recently.

  10. The effect of toxins on inorganic phosphate release during actin polymerization.

    PubMed

    Vig, Andrea; Ohmacht, Róbert; Jámbor, Eva; Bugyi, Beáta; Nyitrai, Miklós; Hild, Gábor

    2011-05-01

    During the polymerization of actin, hydrolysis of bound ATP occurs in two consecutive steps: chemical cleavage of the high-energy nucleotide and slow release of the γ-phosphate. In this study the effect of phalloidin and jasplakinolide on the kinetics of P(i) release was monitored during the formation of actin filaments. An enzyme-linked assay based spectrophotometric technique was used to follow the liberation of inorganic phosphate. It was verified that jasplakinolide reduced the P(i) release in the same way as phalloidin. It was not possible to demonstrate long-range allosteric effects of the toxins by release of P(i) from F-actin. The products of ATP hydrolysis were released by denaturation of the actin filaments. HPLC analysis of the samples revealed that the ATP in the toxin-bound region was completely hydrolysed into ADP and P(i). The effect of both toxins can be sufficiently explained by local and mechanical blockade of P(i) dissociation.

  11. Imaging Cellular Inorganic Phosphate in Caenorhabditis elegans Using a Genetically Encoded FRET-Based Biosensor

    PubMed Central

    Banerjee, Swayoma; Versaw, Wayne K.; Garcia, L. Rene

    2015-01-01

    Inorganic phosphate (Pi) has central roles in metabolism, cell signaling and energy conversion. The distribution of Pi to each cell and cellular compartment of an animal must be tightly coordinated with its dietary supply and with the varied metabolic demands of individual cells. An analytical method for monitoring Pi dynamics with spatial and temporal resolution is therefore needed to gain a comprehensive understanding of mechanisms governing the transport and recycling of this essential nutrient. Here we demonstrate the utility of a genetically encoded FRET-based Pi sensor to assess cellular Pi levels in the nematode Caenorhabditis elegans. The sensor was expressed in different cells and tissues of the animal, including head neurons, tail neurons, pharyngeal muscle, and the intestine. Cytosolic Pi concentrations were monitored using ratiometric imaging. Injection of phosphate buffer into intestinal cells confirmed that the sensor was responsive to changes in Pi concentration in vivo. Live Pi imaging revealed cell-specific and developmental stage-specific differences in cytosolic Pi concentrations. In addition, cellular Pi levels were perturbed by food deprivation and by exposure to the respiratory inhibitor cyanide. These results suggest that Pi concentration is a sensitive indicator of metabolic status. Moreover, we propose that live Pi imaging in C. elegans is a powerful approach to discern mechanisms that govern Pi distribution in individual cells and throughout an animal. PMID:26484766

  12. Three-step preparation and purification of phosphorus-33-labeled creatine phosphate of high specific activity

    SciTech Connect

    Savabi, F.; Geiger, P.J.; Bessman, S.P.

    1984-03-01

    Rabbit heart mitochondria were used as a source of enzymes for the synthesis of phosphorus-labeled creatine phosphate. This method is based on the coupled reaction between mitochondrial oxidative phosphorylation and mitochondrial-bound creatine kinase. It is possible to convert more than 90% of the inorganic phosphate (P/sub i/) to creatine phosphate. The method used only small amounts of adenine nucleotides which led to a product with only slight nucleotide contamination. This could be removed by activated charcoal extraction. For further purification, a method for the removal of residual P/sub i/ is described. 20 references.

  13. Effect of decreasing dietary phosphorus supply on net recycling of inorganic phosphate in lactating dairy cows.

    PubMed

    Puggaard, L; Kristensen, N B; Sehested, J

    2011-03-01

    Five ruminally cannulated lactating Holstein cows, fitted with permanent indwelling catheters in the mesenteric vein, hepatic vein, portal vein, and an artery were used to study intestinal absorption and net recycling of inorganic phosphate (P(i)) to the gastrointestinal tract. Treatments were low P (LP; 2.4 g of P/kg of DM) and high P (HP; 3.4 g of P/kg of DM). The dietary total P (tP) concentrations were obtained by replacing 0.50% calcium carbonate in the LP diet with 0.50% monocalcium phosphate in the HP diet. Diets were fed for 14 d and cows were sampled on d 14 in each period. Cows were fed restrictively, resulting in equal dry matter intakes as well as milk, fat, and protein yields between treatments. Net P(i) recycling (primarily salivary) was estimated as the difference between net portal plasma flux (net absorption of P(i)) and apparently digested tP (feed - fecal tP difference). Phosphorus intake, apparently digested tP, and fecal tP excretion decreased with LP. An effect of decreased tP intake on net portal plasma flux of P(i) could not be detected. However, despite numerically minute net fluxes across the liver, the net splanchnic flux of P(i) was less in LP compared with that in HP. Though arterial plasma P(i) concentration decreased, net P(i) recycling was not decreased when tP intake was decreased, and recycling of P(i) was maintained at the expense of deposition of P(i) in bones. Data are not consistent with salivary P(i) secretion being the primary regulator of P(i) homeostasis at low tP intakes. On the contrary, maintaining salivary P(i) recycling at low tP intakes indicates that rumen function was prioritized at the expense of bone P reserves.

  14. Distinct Effects of Inorganic Phosphate on Cell Cycle and Apoptosis in Human Vascular Smooth Muscle Cells.

    PubMed

    Rahabi-Layachi, Haifa; Ourouda, Roger; Boullier, Agnes; Massy, Ziad A; Amant, Carole

    2015-02-01

    Inorganic phosphate (Pi) is an essential nutrient to all living organisms. Nevertheless, hyperphosphatemia is now recognized as a risk factor for cardiovascular events and mortality in chronic kidney disease (CKD) patients. To our knowledge, the mechanisms by which elevated Pi alters smooth muscle cell proliferation have been poorly addressed. Therefore, in this study, we investigated the effects of Pi on cell cycle regulation and apoptosis in human aortic smooth muscle cells (HAoSMC). HAoSMC were treated with physiologic (1 mM) or high (2 and 3 mM) Pi concentrations. We showed that Pi not only decreased significantly cell viability (P < 0.001) but also induced apoptosis of HAoSMC. Moreover, Pi treatment blocked G1/S cell cycle progression by increasing cell number in G0/G1 phase up to 82.4 ± 3.4% for 3 mM vs 76.2 ± 3.1% for control (P < 0.01) while decreasing cell number in S phase. Accordingly, this was associated with a decrease protein expression of cyclin E and its associated CDK (CDK2), and phosphorylated retinoblastoma protein. Moreover, we observed an increase of protein expression of cell cycle inhibitors p15, p21, and p27. Interestingly, we also found that induction of cell cycle arrest was partially dependent on phosphate uptake. Our results demonstrated that Pi reduced HAoSMC proliferation by inducing apoptosis and cell cycle arrest. Indeed, we showed for the first time that Pi affected HAoSMC cell cycle by blocking G1/S progression. These findings would be useful for a better understanding of molecular mechanisms involved in vascular complications observed in CKD patients. © 2014 Wiley Periodicals, Inc.

  15. High Inorganic Phosphate Intake Promotes Tumorigenesis at Early Stages in a Mouse Model of Lung Cancer

    PubMed Central

    Lee, Somin; Kim, Ji-Eun; Hong, Seong-Ho; Lee, Ah-Young; Park, Eun-Jung; Seo, Hwi Won; Chae, Chanhee; Doble, Philip; Bishop, David; Cho, Myung-Haing

    2015-01-01

    Inorganic phosphate (Pi) is required by all living organisms for the development of organs such as bone, muscle, brain, and lungs, regulating the expression of several critical genes as well as signal transduction. However, little is known about the effects of prolonged dietary Pi consumption on lung cancer progression. This study investigated the effects of a high-phosphate diet (HPD) in a mouse model of adenocarcinoma. K-rasLA1 mice were fed a normal diet (0.3% Pi) or an HPD (1% Pi) for 1, 2, or 4 months. Mice were then sacrificed and subjected to inductively coupled plasma mass/optical emission spectrometry and laser ablation inductively coupled plasma mass-spectrometry analyses, western blot analysis, histopathological, immunohistochemical, and immunocytochemical analyses to evaluate tumor formation and progression (including cell proliferation, angiogenesis, and apoptosis), changes in ion levels and metabolism, autophagy, epithelial-to-mesenchymal transition, and protein translation in the lungs. An HPD accelerated tumorigenesis, as evidenced by increased adenoma and adenocarcinoma rates as well as tumor size. However, after 4 months of the HPD, cell proliferation was arrested, and marked increases in liver and lung ion levels and in energy production via the tricarboxylic acid cycle in the liver were observed, which were accompanied by increased autophagy and decreased angiogenesis and apoptosis. These results indicate that an HPD initially promotes but later inhibits lung cancer progression because of metabolic adaptation leading to tumor cell quiescence. Moreover, the results suggest that carefully regulated Pi consumption are effective in lung cancer prevention. PMID:26285136

  16. Determination of pre-cecal phosphorus digestibility of inorganic phosphates and bone meal products in broilers.

    PubMed

    van Harn, J; Spek, J W; van Vuure, C A; van Krimpen, M M

    2017-05-01

    A broiler study was performed to determine the pre-cecal phosphorus (P) digestibility of 5 P sources, 3 from animal (Delfos, Calfos, and porcine bone meal) and 2 of inorganic (monocalcium phosphate [MCP] and dicalcium phosphate [DCP]) origin. Delfos is processed from bones resulting in a dicalcium phosphate product, and Calfos is processed from bones in which part of the gelatin is removed but in which the hydroxy-apatite matrix is preserved. During the first 14 d, birds were housed in floor pens bedded with wood shavings and received a commercial starter diet. At d 14, broilers were randomly assigned to pens (0.9 m2, 10 birds/pen) with a slatted floor. From d 14 onwards, one of the 6 experimental diets (a basal diet, and 5 diets containing the P sources) was provided. Test diets were replicated 6 times, and the basal diet 8 times. Electron microscopy images of test products were made in order to verify whether the spatial structure of the test products could be related to the pre-cecal P digestibility of the same products. Diets met or exceeded CVB (2011) requirements for all nutrients except for P and were formulated to contain a calcium to total P ratio of between 1.4 and 1.6 and a minimal amount of phytate P. Diets contained 5 g/kg titanium oxide as a marker to determine digestibility of P. At d 24 all birds were euthanized, after which the content of the terminal part of the ileum was sampled. The P digestibility was calculated by linear regression according to World's Poultry Science Association (WPSA) protocol for determination of pre-cecal P digestibility. Pre-cecal P digestibility of MCP, DCP, Delfos, Calfos, and porcine bone meal was 88.5, 82.4, 94.5, 86.9, and 78.2%, respectively. Based on visual inspection of electron microscopy images of test products, the spatial structure of the test products might be related to P digestibility. It is concluded that processing of bone meal increases the pre-cecal P digestibility in broilers. © The Author 2017

  17. Thoroughbred blood serum inorganic phosphate concentrations in relation to feeding regime and racing performance.

    PubMed

    Denny, J E

    1987-06-01

    Horses receiving a pelleted or cubed dietary supplementation with roughage, have serum inorganic phosphate (SIP) concentrations consistently below an accepted mean of 1,032 mmol l-1 or 3, 1 mg dl-1. Further, it has been reported that the best eight, two-year-old Irish Thoroughbred track performers of 51 horses tested over a 10 month period, had significantly lower SIP concentrations than the worst eight track performers. In an endeavour to assess any nutritive effect on SIP concentrations and also to assess any effect of SIP concentrations on track performance, metabolic blood profiles from 303 horses in training at the Summerveld Training centre in Natal, were evaluated for various blood parameters over a two year period. Of these 303 profiles, 264 were analysed for SIP concentrations. These horses were on three known feeding regimes viz. Feed 1--cube feeding plus hay; Feed 2--oats, wheaten bran and greens plus hay; Feed 3--Mixed feeding regime of feeds 1 and 2; Feed 4--unknown regime. Dry matter intake varied between 2 and 2.5% of estimated bodymass and in the Feed 1 regime, the proportion of cubed supplement in the diet was increased from 30 to 70% as the training programme progressed. Statistical analysis of SIP concentrations showed that horses on the Feed 1 regime had significantly lower SIP concentrations than horses on the other feed regimes. Of the 303 profiles, 224 could be identified with actual races.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Plasma Calcium, Inorganic Phosphate and Magnesium During Hypocalcaemia Induced by a Standardized EDTA Infusion in Cows

    PubMed Central

    Mellau, LSB; Jørgensen, RJ; Enemark, JMD

    2001-01-01

    The intravenous Na2EDTA infusion technique allows effective specific chelation of circulating Ca2+ leading to a progressive hypocalcaemia. Methods previously used were not described in detail and results obtained by monitoring total and free ionic calcium were not comparable due to differences in sampling and analysis. This paper describes a standardized EDTA infusion technique that allowed comparison of the response of calcium, phosphorus and magnesium between 2 groups of experimental cows. The concentration of the Na2EDTA solution was 0.134 mol/l and the flow rate was standardized at 1.2 ml/kg per hour. Involuntary recumbency occurred when ionised calcium dropped to 0.39 – 0.52 mmol/l due to chelation. An initial fast drop of ionized calcium was observed during the first 20 min of infusion followed by a fluctuation leading to a further drop until recumbency. Pre-infusion [Ca2+] between tests does not correlate with the amount of EDTA required to induce involuntary recumbence. Total calcium concentration measured by atomic absorption remained almost constant during the first 100 min of infusion but declined gradually when the infusion was prolonged. The concentration of inorganic phosphate declined gradually in a fluctuating manner until recumbency. Magnesium concentration remained constant during infusion. Such electrolyte responses during infusion were comparable to those in spontaneous milk fever. The standardized infusion technique might be useful in future experimental studies. PMID:11503370

  19. Two different mechanisms mediate chemotaxis to inorganic phosphate in Pseudomonas aeruginosa

    PubMed Central

    Rico-Jiménez, Miriam; Reyes-Darias, Jose Antonio; Ortega, Álvaro; Díez Peña, Ana Isabel; Morel, Bertrand; Krell, Tino

    2016-01-01

    Inorganic phosphate (Pi) is a central signaling molecule that modulates virulence in various pathogens. In Pseudomonas aeruginosa, low Pi concentrations induce transcriptional alterations that increase virulence. Also, under low Pi levels, P. aeruginosa exhibits Pi chemotaxis—a process mediated by the two non-paralogous receptors CtpH and CtpL. Here we show that the two receptors operate via different mechanisms. We demonstrate that the ligand binding domain (LBD) of CtpH but not CtpL binds Pi directly. We identify the periplasmic ligand binding protein PstS as the protein that binds in its Pi loaded state to CtpL, resulting in receptor stimulation. PstS forms part of the Pi transporter and has thus a double function in Pi transport and chemotaxis. The affinity of Pi for CtpH was modest whereas that for PstS very high, which may explain why CtpH and CtpL mediate chemotaxis to high and low Pi concentrations, respectively. The pstS/ctpH double mutant was almost devoid of Pi taxis, indicating that PstS is the only CtpL Pi-shuttle. Chemotaxis mechanisms based on indirect ligand recognition were unambiguously identified in enterobacteria. The discovery of a similar mechanism in a different bacterial order, involving a different chemoreceptor type and chemoeffector suggests that such systems are widespread. PMID:27353565

  20. Copper tolerance mediated by polyphosphate degradation and low-affinity inorganic phosphate transport system in Escherichia coli.

    PubMed

    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.

  1. Disturbance of inorganic phosphate metabolism in diabetes mellitus: its impact on the development of diabetic late complications.

    PubMed

    Ditzel, Jørn; Lervang, Hans-Henrik

    2010-09-01

    The pathogenesis of diabetic late complications (DLC) is multifactorial. Studies of mechanisms leading to early functional microvascular changes in retina and kidneys point towards a disturbance in the metabolism of inorganic phosphate (Pi) in diabetes. Since tissue hypoxia and reduced high energy phosphates may be important factors in the development of DLC, the influence of Pi concentration on the metabolism and function of the erythrocytes and renal tubular cells, as well as the relationship of the concentration of Pi to total oxygen consumption, have been reviewed. While extensive research data in non-diabetic conditions support the suggestion, that the Pi concentration is a determining factor in regulation of metabolism and rate of oxygen consumption, diabetes shows the opposite behavior. In diabetes, the highest oxygen consumption is associated with the lowest concentration of Pi. Many conventionally-treated juvenile diabetic patients respond as if their tissues were in a state of chronic hypoxia. A disturbance in phosphate handling occurs in the kidney tubules, where the excessive sodium-dependent glucose entry in diabetics depolarizes the electrochemical sodium gradient and consequently impairs inorganic phosphate reabsorption. Similar changes may occur in other cells and tissues in which glucose entry is not controlled by insulin, and particularly in poorly-regulated diabetic patients in whom long-term vascular complications are more likely.

  2. Extracellular inorganic phosphate regulates gibbon ape leukemia virus receptor-2/phosphate transporter mRNA expression in rat bone marrow stromal cells.

    PubMed

    Wada, Keinoshin; Mizuno, Morimichi; Komori, Takahide; Tamura, Masato

    2004-01-01

    In mammalian cells, several observations indicate not only that phosphate transport probably regulates local inorganic phosphate (Pi) concentration, but also that Pi affects normal cellular metabolism, which in turn regulates apoptosis and the process of mineralization. To elucidate how extracellular Pi regulates cellular functions of pre-osteoblastic cells, we investigated the expression of type III sodium (Na)-dependent Pi transporters in rat bone marrow stromal cells and ROB-C26 pre-osteoblastic cells. The mRNA expression level of gibbon ape leukemia virus receptor (Glvr)-2 was increased by the addition of Pi in rat bone marrow stromal cells, but not in ROB-C26 or normal rat kidney (NRK) cells. In contrast, the level of Glvr-1 mRNA was not altered by the addition of extracellular Pi in these cells. The induction of Glvr-2 mRNA by Pi was inhibited in the presence of cycloheximide (CHX). Moreover, mitogen-activated protein kinase (MEK) /extracellular-signal-regulated kinase (ERK) pathway inhibitors; U0126 (1.4-diamino-2, 3-dicyano-1, 4-bis [2-amino-phenylthio] butadiene) and PD98059 (2'-Amino-3'-methoxyflavone) inhibited inducible Glvr-2 mRNA expression, but p38 MEK inhibitor SB203580 [4-(4'-fluorophenyl)-2-(4'-methyl-sulfinylphenyl)-5-(4'pyridyl) imidazole] did not inhibit the induction of Glvr-2 mRNA expression, suggesting that extracellular Pi regulates de novo protein synthesis and MEK/ERK activity in rat bone marrow stromal cells, and through these, induction of Glvr-2 mRNA. Although Pi also induced osteopontin mRNA expression in rat bone marrow stromal cells but not in ROB-C26 and NRK cells, changes in cell viability with the addition of Pi were similar in both cell types. These data indicate that extracellular Pi regulates Glvr-2 mRNA expression, provide insights into possible mechanisms whereby Pi may regulate protein phosphorylation, and suggest a potential role for the Pi transporter in rat bone marrow stromal cells.

  3. Temperature dependence of rat liver mitochondrial respiration with uncoupling of oxidative phosphorylation by fatty acids. Influence of inorganic phosphate.

    PubMed

    Samartsev, V N; Chezganova, S A; Polishchuk, L S; Paydyganov, A P; Vidyakina, O V; Zeldi, I P

    2003-06-01

    The respiration rate of liver mitochondria in the course of succinate oxidation depends on temperature in the presence of palmitate more strongly than in its absence (in state 4). In the Arrhenius plot, the temperature dependence of the palmitate-induced stimulation of respiration has a bend at 22 degrees C which is characterized by transition of the activation energy from 120 to 60 kJ/mol. However, a similar dependence of respiration in state 4 is linear over the whole temperature range and corresponds to the activation energy of 17 kJ/mol. Phosphate partially inhibits the uncoupling effect of palmitate. This effect of phosphate is increased on decrease in temperature. In the presence of phosphate the temperature dependence in the Arrhenius plot also has a bend at 22 degrees C, and the activation energy increases from 128 to 208 kJ/mol in the range from 13 to 22 degrees C and from 56 to 67 kJ/mol in the range from 22 to 37 degrees C. Mersalyl (10 nmol/mg protein), an inhibitor of the phosphate carrier, similarly to phosphate, suppresses the uncoupling effect of laurate, and the effects of mersalyl and phosphate are not additive. The recoupling effects of phosphate and mersalyl seem to show involvement of the phosphate carrier in the uncoupling effect of fatty acids in liver mitochondria. Possible mechanisms of involvement of the phosphate carrier in the uncoupling effect of fatty acids are discussed.

  4. Seminal Plasma pH, Inorganic Phosphate, Total and Ionized Calcium Concentrations In The Assessment of Human Spermatozoa Function

    PubMed Central

    Banjoko, S. Olatunbosun; Adeseolu, Fasiu O.

    2013-01-01

    Introduction: Fertilization in humans is dependent on viability of the male spermatozoa among other factors and there have been conflicting reports on the role of pH, calcium and phosphate concentrations in sperm function. This study therefore aimed to investigate seminal plasma pH, inorganic phosphate, total and ionized calcium concentrations relative to spermatozoa function. Material and Methods: Seminal plasma concentrations of pH, total calcium, ionized calcium (Ca++); inorganic phosphate, motility and spermatozoa count were determined in 80 males by standard methods. Results: Forty-nine of the subjects had normal spermatozoa motility (> 60%) and 31 had hypomotility (< 60%). The hypomotility group exhibited lower calcium ion (Ca2+) concentrations; 0.19+0.01mmol/L compared with normal motility group; 0.24+0.01mmol/L (p<0.001) the latter also had significantly higher inorganic phosphate; 7.83+1.27 while the former had 5.64+1.62mmol/L (p= 0.004). The mean spermatozoa counts for hypomotility and normal motility group were 42.0 ± 13 x 106 , 72.35 + 20 x 106 respectively (p< 0.001). No significant differences were observed in pH, volume of ejaculate and total calcium concentration between the hypomotility and normal motility groups The mean concentrations of pH were 7.51 ± 0.02 and 7.54 ± 0.03 respectively (p= 0.21) and total calcium; 3.10 ± 0.12 and 3.36 ± 0.14mmol/L respectively (p= 0.16 ). There was a significant difference in percentage of abnormal forms in both groups with hypomotile group having 36% compared to mormal motility group with 5% (p< 0.05). Conclusion: Correlations were observed between seminal concentrations of calcium ions, inorganic phosphate, spermatozoa count and motility but not with total calcium concentrations and pH and therefore should be considered in understanding male infertility and preparation of media for sperm preservation for in vitro fertilization. PMID:24392378

  5. Can inorganic phosphate explain sag during unfused tetanic contractions of skeletal muscle?

    PubMed

    Smith, Ian C; Bellissimo, Catherine; Herzog, Walter; Tupling, A Russell

    2016-11-01

    We test the hypothesis that cytosolic inorganic phosphate (Pi) can account for the contraction-induced reductions in twitch duration which impair summation and cause force to decline (sag) during unfused tetanic contractions of fast-twitch muscle. A five-state model of crossbridge cycling was used to simulate twitch and unfused tetanic contractions. As Pi concentration ([Pi]) was increased from 0 to 30 mmol·L(-1), twitch duration decreased, with progressive reductions in sensitivity to Pi as [Pi] was increased. When unfused tetani were simulated with rising [Pi], sag was most pronounced when initial [Pi] was low, and when the magnitude of [Pi] increase was large. Fast-twitch extensor digitorum longus (EDL) muscles (sag-prone, typically low basal [Pi]) and slow-twitch soleus muscles (sag-resistant, typically high basal [Pi]) were isolated from 14 female C57BL/6 mice. Muscles were sequentially incubated in solutions containing either glucose or pyruvate to create typical and low Pi environments, respectively. Twitch duration was greater (P < 0.05) in pyruvate than glucose in both muscles. Stimuli applied at intervals approximately three times the time to peak twitch tension resulted in sag of 35.0 ± 3.7% in glucose and 50.5 ± 1.4% in pyruvate in the EDL (pyruvate > glucose; P < 0.05), and 3.9 ± 0.3% in glucose and 37.8 ± 2.7% in pyruvate in the soleus (pyruvate > glucose; P < 0.05). The influence of Pi on crossbridge cycling provides a tenable mechanism for sag. Moreover, the low basal [Pi] in fast-twitch relative to slow-twitch muscle has promise as an explanation for the fiber-type dependency of sag. © 2016 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  6. Effect of various vitamin D metabolites on serum calcium and inorganic phosphate in the freshwater snake Natrix piscator.

    PubMed

    Srivastav, A K; Srivastav, S K; Singh, S; Norman, A W

    1995-10-01

    Vitamin D3 (650 pmol and 6.50 nmol/100 g body wt), 25-hydroxyvitamin D (650 pmol and 6.50 nmol/100 g body wt), and 1,25-dihydroxyvitamin D (65 pmol and 650 pmol/100 g body wt) were administered daily to the freshwater snake Natrix piscator for 15 days. Both serum calcium and inorganic phosphate levels were increased significantly in all of the treated groups. This is the first report of hypercalcemia and hyperphosphatemia in reptiles induced by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D.

  7. Interaction of the aziridine moiety of RSU-1069 with nucleotides and inorganic phosphate. Implications for alkylation of DNA.

    PubMed

    Silver, A R; O'Neill, P

    1986-04-01

    The aziridine moiety of RSU-1069 (1-(2-nitro-1-imidazolyl)-3-(1-aziridino-2-propanol] alkylates inorganic phosphate and a range of nucleotides in aqueous solutions of pH 7.0. From the rate constants obtained and a study of the adducts formed it is demonstrated that phosphate is a major target on nucleotides at neutral pH, although additional sites may exist particularly on dGMP and dAMP. From the dependence of reactivity on pH and the influence of ionic strength, it is established that the protonated aziridine is the reactive species and that hydrolysis is insignificant when compared to the rate of phosphorylation. The reaction kinetics detailed in this study are discussed in terms of DNA alkylation and strand breakage effected by the aziridine moiety of RSU-1069.

  8. Developmental differences and regional similarities in the responses of rat cardiac skinned muscles to acidosis, inorganic phosphate and caffeine.

    PubMed

    Palmer, S; Kentish, J C

    1996-04-01

    The Ca2+ sensitivity of cardiac myofibrillar force production can be decreased by acidosis or inorganic phosphate (P(i)) and increased by caffeine. To investigate whether the source of tissue influences the potency of these agents, we compared the actions of acidosis (change of pH from 7.0 to 6.2), P(i) and caffeine (both 20 mM) on force production of skinned cardiac muscles from adult ventricle, adult atrium and neonate ventricle of the rat. Maximum Ca(2+)-activated force was reduced by all three interventions and the responses of the different muscle types to a given intervention were similar. Acidosis reduced myofibrillar Ca2+ sensitivity by 1.09 and 1.04 pCa units in adult ventricle and atrium, respectively, and P(i) reduced it by 0.19 and 0.22 pCa units. However, each effect was only one-third as great in the neonate ventricle, which showed falls of 0.33 pCa units for acidosis and 0.06 for P(i). In contrast, caffeine raised the Ca2+ sensitivity by the same amount (approximately 0.4 pCa units) in all three muscle types. The differential effect between adult and neonate seen with both acidosis and P(i) suggests some similarity in the mechanisms by which these factors decrease Ca2+ sensitivity. In contrast, the equal effects of caffeine on neonate and adult suggests that caffeine acts by a completely different mechanism. The lower pH- and P(i)-sensitivity of the neonatal ventricle can help to explain why neonatal and adult myocardium exhibit differential force responses to ischaemia (or hypoxia alone).

  9. Activation by Gene Amplification of pitB, Encoding a Third Phosphate Transporter of Escherichia coli K-12

    PubMed Central

    Hoffer, Sally M.; Schoondermark, Paul; van Veen, Hendrik W.; Tommassen, Jan

    2001-01-01

    Two systems for the uptake of inorganic phosphate (Pi) in Escherichia coli, PitA and Pst, have been described. A revertant of a pitA pstS double mutant that could grow on Pi was isolated. We demonstrate that the expression of a new Pi transporter, PitB, is activated in this strain by a gene amplification event. PMID:11443103

  10. High Inorganic Triphosphatase Activities in Bacteria and Mammalian Cells: Identification of the Enzymes Involved

    PubMed Central

    Lakaye, Bernard; Servais, Anne-Catherine; Scholer, Georges; Fillet, Marianne; Elias, Benjamin; Derochette, Jean-Michel; Crommen, Jacques; Wins, Pierre; Bettendorff, Lucien

    2012-01-01

    Background We recently characterized a specific inorganic triphosphatase (PPPase) from Nitrosomonas europaea. This enzyme belongs to the CYTH superfamily of proteins. Many bacterial members of this family are annotated as predicted adenylate cyclases, because one of the founding members is CyaB adenylate cyclase from A. hydrophila. The aim of the present study is to determine whether other members of the CYTH protein family also have a PPPase activity, if there are PPPase activities in animal tissues and what enzymes are responsible for these activities. Methodology/Principal Findings Recombinant enzymes were expressed and purified as GST- or His-tagged fusion proteins and the enzyme activities were determined by measuring the release of inorganic phosphate. We show that the hitherto uncharacterized E. coli CYTH protein ygiF is a specific PPPase, but it contributes only marginally to the total PPPase activity in this organism, where the main enzyme responsible for hydrolysis of inorganic triphosphate (PPPi) is inorganic pyrophosphatase. We further show that CyaB hydrolyzes PPPi but this activity is low compared to its adenylate cyclase activity. Finally we demonstrate a high PPPase activity in mammalian and quail tissue, particularly in the brain. We show that this activity is mainly due to Prune, an exopolyphosphatase overexpressed in metastatic tumors where it promotes cell motility. Conclusions and General Significance We show for the first time that PPPase activities are widespread in bacteria and animals. We identified the enzymes responsible for these activities but we were unable to detect significant amounts of PPPi in E. coli or brain extracts using ion chromatography and capillary electrophoresis. The role of these enzymes may be to hydrolyze PPPi, which could be cytotoxic because of its high affinity for Ca2+, thereby interfering with Ca2+ signaling. PMID:22984449

  11. A method for analyzing the δ18O of resin-extractable soil inorganic phosphate.

    PubMed

    Weiner, Tal; Mazeh, Shunit; Tamburini, Federica; Frossard, Emmanuel; Bernasconi, Stefano M; Chiti, Tommaso; Angert, Alon

    2011-03-15

    Improved tools for tracing phosphate transformations in soils are much needed, and can lead to a better understanding of the terrestrial phosphorus cycle. The oxygen stable isotopes in soil phosphate are still not exploited in this regard. Here we present a method for measuring the oxygen stable isotopes in a fraction of the soil phosphate which is rapidly available to plants, the resin-extractable P. This method is based on extracting available phosphate from the soil with anion-exchange membranes, soil organic matter removal by a resin, purification by precipitation as cerium phosphate, and finally precipitation as silver phosphate. The purified silver phosphate samples are then measured by a high-temperature elemental analyzer (HT-EA) coupled in continuous flow mode to an isotope ratio mass spectrometer. Testing the method with Mediterranean and semi-arid soils showed no artifacts, as well as good reproducibility in the same order as that of the HT-EA analytical uncertainty (0.3‰). Copyright © 2011 John Wiley & Sons, Ltd.

  12. Inorganic-organic hybrid nanoparticles with biocompatible calcium phosphate thin shells for fluorescence enhancement.

    PubMed

    Bastakoti, Bishnu Prasad; Hsu, Yin-Chu; Liao, Shih-Hsiang; Wu, Kevin C-W; Inoue, Masamichi; Yusa, Shin-ichi; Nakashima, Kenichi; Yamauchi, Yusuke

    2013-06-01

    Polymeric micelles consisting of asymmetric triblock copolymers were successfully used for fabrication of robust hybrid nanoparticles with highly biocompatible calcium phosphate shells. The hydrophobic polystyrene core encapsulates hydrophobic fluorescent dyes such as Nile red. The anionic polyacrylic acid provides the site for the mineralization reaction of calcium phosphate. The polyethylene glycol corona stabilizes the hybrid nanoparticles. Fluorescent dyes can be used as imaging agents for determining the location of the nanoparticles and to give an observable indication of drug delivery, while the calcium phosphate shell can enhance the fluorescence of the encapsulated dye. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Influence of pH and inorganic phosphate on toxicity of zinc to Arthrobacter sp. isolated from heavy-metal-contaminated sediments.

    PubMed

    Moberly, James G; Staven, Ari; Sani, Rajesh K; Peyton, Brent M

    2010-10-01

    Because of its high solubility over a wide range of pH conditions, zinc is found in many natural and human-impacted systems. Zinc speciation is critical in assessing zinc toxicity to microorganisms because it varies considerably with pH and is dependent on other aqueous constituents. Combined results of thermodynamic modeling, statistical analysis, and batch culture studies using Arthrobacter sp. JM018 suggest that the toxic species may not be solely limited to the free ion, but also includes ZnHPO(4)(0)(aq). Cellular uptake of ZnHPO(4)(0)(aq) through the inorganic phosphate transporter (Pit family), which requires a neutral metal phosphate complex for phosphate transport, may explain the observed toxicity. Based on visual MINTEQ (v3.0) modeling, at 50 μM total zinc, ZnHPO(4)(0)(aq) constitutes 33, 70, and 76% of the neutral metal phosphate pool at pH 6, 7, and 8, respectively. At 50 μM total zinc, cultures supplied with organic phosphate (glycerol-3-phosphate) show no significant response to pH (p = 0.13) while inhibition of inorganic phosphate-supplemented cultures, whose neutral metal phosphates are increasingly dominated by ZnHPO(4)(0)(aq), show significant pH dependence (p = 9.45 × 10(-7)). Using sodium to decrease the distribution of ZnHPO(4)(0)(aq) in the neutral metal phosphate pool also decreased the pH dependent toxicity, further supporting this mechanism. These findings show the important role of minor zinc species in organism toxicity and have wider implications because the Pit inorganic phosphate transport system is widely distributed in Bacteria, Archaea, and Eukarya.

  14. Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests.

    PubMed

    Zhu, Feifei; Lu, Xiankai; Liu, Lei; Mo, Jiangming

    2015-01-21

    Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al(3+) replacement of Ca(2+) in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K(+)+Ca(2+)+Mg(2+)) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests.

  15. Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests

    PubMed Central

    Zhu, Feifei; Lu, Xiankai; Liu, Lei; Mo, Jiangming

    2015-01-01

    Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al3+ replacement of Ca2+ in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K++Ca2++Mg2+) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests. PMID:25605567

  16. Substrate activity of synthetic formyl phosphate in the reaction catalyzed by formyltetrahydrofolate synthetase

    SciTech Connect

    Smithers, G.W.; Jahansouz, H.; Kofron, J.L.; Himes, R.H.; Reed, G.H.

    1987-06-30

    Formyl phosphate, a putative enzyme-bound intermediate in the reaction catalyzed by formyltetrahydrofolate synthetase (EC 6.3.4.3), was synthesized from formyl fluoride and inorganic phosphate, and the product was characterized by /sup 31/P, /sup 1/H, and /sup 13/C nuclear magnetic resonance (NMR). Measurement of hydrolysis rates by /sup 31/P NMR indicates that formyl phosphate is particularly labile, with a half-life of 48 min in a buffered neutral solution at 20 /sup 0/C. At pH 7, hydrolysis occurs with P-O bond cleavage, as demonstrated by /sup 18/O incorporation from H/sub 2//sup 18/O into P/sub i/, while at pH 1 and pH 13 hydrolysis occurs with C-O bond cleavage. The substrate activity of formyl phosphate was tested in the reaction catalyzed by formyltetrahydrofolate synthetase isolated from Clostridium cylindrosporum. Formyl phosphate supports the reaction in both the forward and reverse directions. Thus, N/sup 10/-formyltetrahydrofolate is produced from tetrahydrofolate and formyl phosphate in a reaction mixture that contains enzyme, Mg(II), and ADP, and ATP is produced from formyl phosphate and ADP with enzyme, Mg(II), and tetrahydrofolate present. The requirements for ADP and for tetrahydrofolate as cofactors in these reactions are consistent with previous steady-state kinetic and isotope exchange studies, which demonstrated that all substrate subsites must be occupied prior to catalysis. The k/sub cat/ values for both the forward and reverse directions, with formyl phosphate as the substrate, are much lower than those for the normal forward and reverse reactions. Kinetic analysis of the formyl phosphate supported reactions indicates that the low steady-state rates observed for the synthetic intermediate are most likely due to the sequential nature of the normal reaction.

  17. Structure of human farnesyl pyrophosphate synthase in complex with an aminopyridine bisphosphonate and two molecules of inorganic phosphate

    SciTech Connect

    Park, Jaeok; Lin, Yih-Shyan; Tsantrizos, Youla S.; Berghuis, Albert M.

    2014-02-19

    A co-crystal structure of human farnesyl pyrophosphate synthase in complex with an aminopyridine bisphosphonate, YS0470, and two molecules of inorganic phosphate has been determined. The identity of the phosphate ligands was confirmed by anomalous diffraction data. Human farnesyl pyrophosphate synthase (hFPPS) produces farnesyl pyrophos@@phate, an isoprenoid essential for a variety of cellular processes. The enzyme has been well established as the molecular target of the nitrogen-containing bisphosphonates (N-BPs), which are best known for their antiresorptive effects in bone but are also known for their anticancer properties. Crystal structures of hFPPS in ternary complexes with a novel bisphosphonate, YS0470, and the secondary ligands inorganic phosphate (P{sub i}), inorganic pyrophosphate (PP{sub i}) and isopentenyl pyrophosphate (IPP) have recently been reported. Only the co-binding of the bisphosphonate with either PP{sub i} or IPP resulted in the full closure of the C-@@terminal tail of the enzyme, a conformational change that is required for catalysis and that is also responsible for the potent in vivo efficacy of N-BPs. In the present communication, a co-crystal structure of hFPPS in complex with YS0470 and two molecules of P{sub i} is reported. The unusually close proximity between these ligands, which was confirmed by anomalous diffraction data, suggests that they interact with one another, with their anionic charges neutralized in their bound state. The structure also showed the tail of the enzyme to be fully disordered, indicating that simultaneous binding of two P{sub i} molecules with a bisphosphonate cannot induce the tail-closing conformational change in hFPPS. Examination of homologous FPPSs suggested that this ligand-dependent tail closure is only conserved in the mammalian proteins. The prevalence of P{sub i}-bound hFPPS structures in the PDB raises a question regarding the in vivo relevance of P{sub i} binding to the function of the enzyme.

  18. Optimization and validation of a rapid method to determine citrate and inorganic phosphate in milk by capillary electrophoresis.

    PubMed

    Izco, J M; Tormo, M; Harris, A; Tong, P S; Jimenez-Flores, R

    2003-01-01

    Quantification of phosphate and citrate compounds is very important because their distribution between soluble and colloidal phases of milk and their interactions with milk proteins influence the stability and some functional properties of dairy products. The aim of this work was to optimize and validate a capillary electrophoresis method for the rapid determination of these compounds in milk. Various parameters affecting analysis have been optimized, including type, composition, and pH of the electrolyte, and sample extraction. Ethanol, acetonitrile, sulfuric acid, water at 50 degrees C or at room temperature were tested as sample buffers (SB). Water at room temperature yielded the best overall results and was chosen for further validation. The extraction time was checked and could be shortened to less than 1 min. Also, sample preparation was simplified to pipet 12 microl of milk into 1 ml of water containing 20 ppm of tartaric acid as an internal standard. The linearity of the method was excellent (R2 > 0.999) with CV values of response factors <3%. The detection limits for phosphate and citrate were 5.1 and 2.4 nM, respectively. The accuracy of the method was calculated for each compound (103.2 and 100.3%). In addition, citrate and phosphate content of several commercial milk samples were analyzed by this method, and the results deviated less than 5% from values obtained when analyzing the samples by official methods. To study the versatility of the technique, other dairy productssuch as cream cheese, yogurt, or Cheddar cheese were analyzed and accuracy was similar to milk in all products tested. The procedure is rapid and offers a very fast and simple sample preparation. Once the sample has arrived at the laboratory, less than 5 min (including handling, preparation, running, integration, and quantification) are necessary to determine the concentration of citric acid and inorganic phosphate. Because of the speed and accuracy of this method, it is promising as an

  19. 2,3-diphosphoglycerate phosphatase activity of phosphoglycerate mutase: stimulation by vanadate and phosphate

    SciTech Connect

    Stankiewicz, P.J.; Gresser, M.J.; Tracey, A.S.; Hass, L.F.

    1987-03-10

    The binding of inorganic vanadate (V/sub i/) to rabbit muscle phosphoglycerate mutase (PGM), studied by using /sup 51/V nuclear magnetic resonance spectroscopy, shows a sigmoidal dependence on vanadate concentration with a stoichiometry of four vanadium atoms per PGM molecule at saturating (V/sub i/). The data are consistent with binding of one divanadate ion to each of the two subunits of PGM in a noncooperative manner with an intrinsic dissociation constant of 4 x 10/sup -6/ M. The relevance of this result to other studies which have shown that the V/sub i/-stimulated 2,3-diphosphoglycerate (2,3-DPG) phosphatase activity of PGM has a sigmoidal dependence on (V/sub i/) with a Hill coefficient of 2.0 is discussed. At pH 7.0, inorganic phosphate has little effect on the 2,3-DPG phosphatase activity of PGM, even at concentrations as high as 50 mM. Similarly, 25 ..mu..M V/sub i/ has little effect on the phosphatase activity. However, in the presence of 25 ..mu..M V/sub i/, a phosphate concentration of 20 mM increases the phosphatase activity by more than 3-fold. This behavior is rationalized in terms of activation of the phosphatase activity by a phosphate/vanadate mixed anhydride. This interpretation is supported by the observation of strong activation of the phosphatase activity by inorganic pyrophosphate. A molecular mechanism for the observed effects of vanadate is proposed, and the relevance of this study to the possible use of vanadate as a therapeutic agent for the treatment of sickle cell anemia is discussed.

  20. Nitrate and phosphate leaching in a Phaeozem soil treated with biosolids, composted biosolids and inorganic fertilizers.

    PubMed

    Esteller, M V; Martínez-Valdés, H; Garrido, S; Uribe, Q

    2009-06-01

    The use of organic wastes in agriculture may increase the production of crops by incorporating organic matter and nutrients into the soil, and by improving its physical characteristics; however, this use may cause environmental problems such as the leaching of certain ions. The objective of this study was to establish possible nitrogen and phosphorus leaching under real field conditions in Phaeozem soils. The experimental work was performed in a corn (Zea mays L.) field where three plots were conditioned with inorganic fertilizer, three plots with 4.5 Mgha(-1) of biosolids on dry basis, and three plots with the same amount of composted biosolids. The quality of biosolids and composted biosolids complied with the Mexican Official Standards. Soil water samples were collected with suction cups during two agricultural cycles and were analysed. Soil samples were also taken and analysed. The N-NO(3) concentrations in soil water fluctuated between 0.9 and 98mgL(-1) in the composted biosolid treatment, between 0.7 and 64 mgL(-1) in the biosolid treatment, and between 1 and 61 mgL(-1) in the inorganic fertilizer treatment. The maximum concentration of N-NO(2) and N-NH(3) in soil water was 1.02 and 2.65 mgL(-1), respectively. The greatest percentage of nitrogen leached is produced when inorganic fertilizer is used (37.4% and 24.0% N leached in the first and second years, respectively), followed by composted biosolids (17.1% and 13.5% N leached in the first and second years, respectively) and last by biosolids (11% for both years). This difference could be related to the form in which nitrogen is present in the fertilizers, while commercial fertilizer is as inorganic nitrogen, organic wastes are basically presented as organic nitrogen. The maximum PO(4)(3-) concentration in soil water was 1.9 mgL(-1) in the composted biosolid treatment, 1.7mgL(-1) in the biosolid treatment and 0.9 mgL(-1) in the inorganic fertilizer treatment. The estimated percentage of leached phosphorus

  1. Crystallization and preliminary X-ray diffraction analysis of a high-affinity phosphate-binding protein endowed with phosphatase activity from Pseudomonas aeruginosa PAO1.

    PubMed

    Djeghader, Ahmed; Gotthard, Guillaume; Suh, Andrew; Gonzalez, Daniel; Scott, Ken; Chabriere, Eric; Elias, Mikael

    2013-10-01

    In prokaryotes, phosphate starvation induces the expression of numerous phosphate-responsive genes, such as the pst operon including the high-affinity phosphate-binding protein (PBP or pstS) and alkaline phosphatases such as PhoA. This response increases the cellular inorganic phosphate import efficiency. Notably, some Pseudomonas species secrete, via a type-2 secretion system, a phosphate-binding protein dubbed LapA endowed with phosphatase activity. Here, the expression, purification, crystallization and X-ray data collection at 0.87 Å resolution of LapA are described. Combined with biochemical and enzymatic characterization, the structure of this intriguing phosphate-binding protein will help to elucidate the molecular origin of its phosphatase activity and to decipher its putative role in phosphate uptake.

  2. Long-term nitrogen fertilization decreased the abundance of inorganic phosphate solubilizing bacteria in an alkaline soil

    PubMed Central

    Zheng, Bang-Xiao; Hao, Xiu-Li; Ding, Kai; Zhou, Guo-Wei; Chen, Qing-Lin; Zhang, Jia-Bao; Zhu, Yong-Guan

    2017-01-01

    Inorganic phosphate solubilizing bacteria (iPSB) are essential to facilitate phosphorus (P) mobilization in alkaline soil, however, the phylogenetic structure of iPSB communities remains poorly characterized. Thus, we use a reference iPSB database to analyze the distribution of iPSB communities based on 16S rRNA gene illumina sequencing. Additionally, a noval pqqC primer was developed to quantify iPSB abundance. In our study, an alkaline soil with 27-year fertilization treatment was selected. The percentage of iPSB was 1.10~2.87% per sample, and the dominant iPSB genera were closely related to Arthrobacter, Bacillus, Brevibacterium and Streptomyces. Long-term P fertilization had no significant effect on the abundance of iPSB communities. Rather than P and potassium (K) additions, long-term nitrogen (N) fertilization decreased the iPSB abundance, which was validated by reduced relative abundance of pqqC gene (pqqC/16S). The decreased iPSB abundance was strongly related to pH decline and total N increase, revealing that the long-term N additions may cause pH decline and subsequent P releases relatively decreasing the demands of the iPSB community. The methodology and understanding obtained here provides insights into the ecology of inorganic P solubilizers and how to manipulate for better P use efficiency. PMID:28181569

  3. Long-term nitrogen fertilization decreased the abundance of inorganic phosphate solubilizing bacteria in an alkaline soil

    NASA Astrophysics Data System (ADS)

    Zheng, Bang-Xiao; Hao, Xiu-Li; Ding, Kai; Zhou, Guo-Wei; Chen, Qing-Lin; Zhang, Jia-Bao; Zhu, Yong-Guan

    2017-02-01

    Inorganic phosphate solubilizing bacteria (iPSB) are essential to facilitate phosphorus (P) mobilization in alkaline soil, however, the phylogenetic structure of iPSB communities remains poorly characterized. Thus, we use a reference iPSB database to analyze the distribution of iPSB communities based on 16S rRNA gene illumina sequencing. Additionally, a noval pqqC primer was developed to quantify iPSB abundance. In our study, an alkaline soil with 27-year fertilization treatment was selected. The percentage of iPSB was 1.10~2.87% per sample, and the dominant iPSB genera were closely related to Arthrobacter, Bacillus, Brevibacterium and Streptomyces. Long-term P fertilization had no significant effect on the abundance of iPSB communities. Rather than P and potassium (K) additions, long-term nitrogen (N) fertilization decreased the iPSB abundance, which was validated by reduced relative abundance of pqqC gene (pqqC/16S). The decreased iPSB abundance was strongly related to pH decline and total N increase, revealing that the long-term N additions may cause pH decline and subsequent P releases relatively decreasing the demands of the iPSB community. The methodology and understanding obtained here provides insights into the ecology of inorganic P solubilizers and how to manipulate for better P use efficiency.

  4. Adsorption of phosphate from aqueous solution using activated red mud

    SciTech Connect

    Pradhan, J.; Das, J.; Das, S.; Thakur, R.S.

    1998-08-01

    Adsorption of phosphate (PO{sub 4}{sup 3{minus}}) from aqueous solution on activated red mud (ARM) was studied as a function of time, pH, temperature, concentration of adsorbent and adsorbate in acetic acid-sodium acetate buffer medium. The adsorption of phosphate follows Langmuir as well as Freundlich adsorption isotherms. The process efficiency was found to be 80--90% at room temperature. This can be extended to the treatment of industrial effluents containing phosphates like that from phosphatic fertilizer plants.

  5. Calcium phosphate-based organic-inorganic hybrid nanocarriers with pH-responsive on/off switch for photodynamic therapy.

    PubMed

    Nomoto, Takahiro; Fukushima, Shigeto; Kumagai, Michiaki; Miyazaki, Kozo; Inoue, Aki; Mi, Peng; Maeda, Yoshinori; Toh, Kazuko; Matsumoto, Yu; Morimoto, Yuji; Kishimura, Akihiro; Nishiyama, Nobuhiro; Kataoka, Kazunori

    2016-05-26

    Photodynamic therapy (PDT) is a promising treatment modality for malignant tumors in a light-selective manner. To improve the PDT efficacy, numerous kinds of nanocarriers have been developed to deliver photosensitizers (PSs) selectively into the tumor through leaky tumor-associated vasculature. However, the corresponding prolonged retention of the nanocarrier in the bloodstream may lead to unfavorable photochemical damage to normal tissues such as skin. Here, we report an organic-inorganic hybrid nanocarrier with a pH-responsive on/off switch of PDT efficacy. This hybrid nanocarrier is constructed by hydrothermal synthesis after simple mixing of calcium/phosphate ions, chlorin e6 (amphiphilic low molecular weight PS), and poly(ethylene glycol)-b-poly(aspartic acid) (PEG-PAsp) copolymers in an aqueous solution. The hybrid nanocarrier possesses a calcium phosphate (CaP) core encapsulating the PSs, which is surrounded by a PEG shielding layer. Under physiological conditions (pH 7.4), the nanocarrier suppressed the photochemical activity of PS by lowering the access of oxygen molecules to the incorporated PS, while PDT efficacy was restored in a pH-responsive manner because of the dissolution of CaP and eventual recovery of access between the oxygen and the PS. Owing to this switch, the nanocarrier reduced the photochemical damage in the bloodstream, while it induced effective PDT efficacy inside the tumor cell in response to the acidic conditions of the endo-/lysosomes.

  6. Hydrophobic and Metallophobic Surfaces: Highly Stable Non-wetting Inorganic Surfaces Based on Lanthanum Phosphate Nanorods

    NASA Astrophysics Data System (ADS)

    Sankar, Sasidharan; Nair, Balagopal N.; Suzuki, Takehiro; Anilkumar, Gopinathan M.; Padmanabhan, Moothetty; Hareesh, Unnikrishnan Nair S.; Warrier, Krishna G.

    2016-03-01

    Metal oxides, in general, are known to exhibit significant wettability towards water molecules because of the high feasibility of synergetic hydrogen-bonding interactions possible at the solid-water interface. Here we show that the nano sized phosphates of rare earth materials (Rare Earth Phosphates, REPs), LaPO4 in particular, exhibit without any chemical modification, unique combination of intrinsic properties including remarkable hydrophobicity that could be retained even after exposure to extreme temperatures and harsh hydrothermal conditions. Transparent nanocoatings of LaPO4 as well as mixture of other REPs on glass surfaces are shown to display notable hydrophobicity with water contact angle (WCA) value of 120° while sintered and polished monoliths manifested WCA greater than 105°. Significantly, these materials in the form of coatings and monoliths also exhibit complete non-wettability and inertness towards molten metals like Ag, Zn, and Al well above their melting points. These properties, coupled with their excellent chemical and thermal stability, ease of processing, machinability and their versatile photo-physical and emission properties, render LaPO4 and other REP ceramics utility in diverse applications.

  7. An experimental-computer modeling study of inorganic phosphates surface adsorption on hydroxyapatite particles.

    PubMed

    Rivas, Manuel; Casanovas, Jordi; del Valle, Luis J; Bertran, Oscar; Revilla-López, Guillermo; Turon, Pau; Puiggalí, Jordi; Alemán, Carlos

    2015-06-07

    The adsorption of orthophosphate, pyrophosphate, triphosphate and a trisphosphonate onto hydroxyapatite has been examined using experiments and quantum mechanical calculations. Adsorption studies with FTIR and X-ray photoelectron spectroscopies have been performed considering both crystalline hydroxyapatite (HAp) and amorphous calcium phosphate particles, which were specifically prepared and characterized for this purpose. Density functional theory (DFT) calculations have been carried out considering the (100) and (001) surfaces of HAp, which were represented using 1 × 2 × 2 and 3 × 3 × 1 slab models, respectively. The adsorption of phosphate onto the two crystallographic surfaces is very much favored from an energetic point of view, which is fully consistent with current interpretations of the HAp growing process. The structures calculated for the adsorption of pyrophosphate and triphosphate evidence that this process is easier for the latter than for the former. Thus, the adsorption of pyrophosphate is severely limited by the surface geometry while the flexibility of triphosphate allows transforming repulsive electrostatic interactions into molecular strain. On the other hand, calculations predict that the trisphosphonate only adsorbs onto the (001) surface of HAp. Theoretical predictions are fully consistent with experimental data. Thus, comparison of DFT results and spectroscopic data suggests that the experimental conditions used to prepare HAp particles promote the predominance of the (100) surface. Accordingly, experimental identification of the adsorption of trisphosphonate onto such crystalline particles is unclear while the adsorption of pyrophosphate and triphosphate is clearly observed.

  8. Hydrophobic and Metallophobic Surfaces: Highly Stable Non-wetting Inorganic Surfaces Based on Lanthanum Phosphate Nanorods

    PubMed Central

    Sankar, Sasidharan; Nair, Balagopal N.; Suzuki, Takehiro; Anilkumar, Gopinathan M.; Padmanabhan, Moothetty; Hareesh, Unnikrishnan Nair S.; Warrier, Krishna G.

    2016-01-01

    Metal oxides, in general, are known to exhibit significant wettability towards water molecules because of the high feasibility of synergetic hydrogen-bonding interactions possible at the solid-water interface. Here we show that the nano sized phosphates of rare earth materials (Rare Earth Phosphates, REPs), LaPO4 in particular, exhibit without any chemical modification, unique combination of intrinsic properties including remarkable hydrophobicity that could be retained even after exposure to extreme temperatures and harsh hydrothermal conditions. Transparent nanocoatings of LaPO4 as well as mixture of other REPs on glass surfaces are shown to display notable hydrophobicity with water contact angle (WCA) value of 120° while sintered and polished monoliths manifested WCA greater than 105°. Significantly, these materials in the form of coatings and monoliths also exhibit complete non-wettability and inertness towards molten metals like Ag, Zn, and Al well above their melting points. These properties, coupled with their excellent chemical and thermal stability, ease of processing, machinability and their versatile photo-physical and emission properties, render LaPO4 and other REP ceramics utility in diverse applications. PMID:26955962

  9. Effect of inorganic salts, soaps and detergents on dissolution and larvicidal activity of alginate formulation of Bacillus sphaericus.

    PubMed

    Vijayan, V; Balaraman, K

    1995-03-01

    Various inorganic salts and commonly used soaps and detergents were tested in the laboratory for their effect on the dissolution and larvicidal residual activity of a slow-release alginate encapsulated granular formation of Bacillus sphaericus. Fluoride, chloride and sulphate salts and a detergent powder affected the residual activity of this formulation drastically by rupturing it but did not effect its larvicidal activity. Nitrates and phosphates of sodium and potassium also had the same effect but to a moderate level. The safest concentration of these water impurities for effective functioning of the alginate encapsulated B. sphaericus formulation have been determined.

  10. Stable organic-inorganic hybrid of polyaniline/α-zirconium phosphate for efficient removal of organic pollutants in water environment.

    PubMed

    Wang, Lei; Wu, Xi-Lin; Xu, Wei-Hong; Huang, Xing-Jiu; Liu, Jin-Huai; Xu, An-Wu

    2012-05-01

    In this article, organic-inorganic hybrid materials of polyaniline/α-zirconium phosphate (PANI/α-ZrP) was synthesized by in situ oxidative polymerization reaction and characterized by Fourier transformed infrared (FTIR), field-emission scanning electron microscopic (FE-SEM) and X-ray diffraction (XRD). The results showed that polyaniline (PANI) was successfully grown on the surface of α-zirconium phosphate (α-ZrP) nanoplates. The PANI/α-ZrP nanocomposites were further applied to remove methyl orange (MO), which was used as a model of organic pollutants in aqueous solution. A synergistic effect of PANI and α-ZrP on promoting the adsorption removal of MO was observed. The PANI/α-ZrP nanocomposites exhibited excellent maximum adsorption capacity toward MO (377.46 mg g(-1)), which is superior to that of PANI nanotubes (254.15 mg g(-1)) and much higher than that of many other adsorbents. The adsorption isotherms of MO can be well-fitted with the Langmuir model and the adsorption kinetics follows the pseudo-second-order model. MO adsorption decreased with increasing solution pH at pH > 4.0 implying that MO adsorption on PANI/α-ZrP may via electrostatic interactions between amine and imine groups on the surface of PANI/α-ZrP and MO molecules. This study implies that the hybrid materials of PANI/α-ZrP can be suggested as potential adsorbents to remove organic dyes from large volumes of aqueous solutions.

  11. Dipolar Coupling Information in Multispin Systems: Application of a Compensated REDOR NMR Approach to Inorganic Phosphates

    NASA Astrophysics Data System (ADS)

    Chan, Jerry C. C.; Eckert, Hellmut

    2000-12-01

    Anexperimental strategy has been developed for measuring multiple dipole-dipole interactions in inorganic compounds using the technique of rotational echo double resonance (REDOR) NMR. Geometry-independent information about the dipole couplings between the observe nuclear species S (arbitrary quantum number) and the heteronuclear species I (spin-{1}/{2}) can be conveniently obtained from the experimental curve of ΔS/S0 versus dipolar evolution time by limiting the analysis to the initial data range 0 < ΔS/S0 < 0.30. Numerical simulations have been carried out on a three-spin system of type SI2 in order to assess the effect of the I-I homonuclear dipole-dipole coupling and the influence of experimental imperfections such as finite pulse length and misadjustments of the 180° pulses applied to the I-spin species. The simulations show further that within the initial data range the effects of such misadjustments can be internally compensated by a modified sequence having an additional 180° pulse on the I channel in the middle of the dipolar evolution periods. Experimental 27Al{31P} REDOR results on the multispin systems Al(PO3)3, AlPO4, [AlPO4]12(C3H7)4NF, and Na3PO4 confirm the general utility of this approach. Thus, for applications to unknown systems the compensation strategy obviates calibration procedures with model compounds.

  12. Phosphate oxygen isotope ratio proxy for specific microbial activity in marine sediments (Peru Margin)

    NASA Astrophysics Data System (ADS)

    Liang, Y.; Blake, R. E.

    2005-12-01

    Oxygen (O) isotope ratios of biogenic apatites have been widely used as paleotemperature and environmental geochemical proxies. With improved knowledge of the phosphate O isotope effects of different P cycling pathways, the δ18O value of inorganic phosphate (δ18OP) has been proposed as a useful proxy and tracer of biological reactions and P cycling in natural environments[1,2,3,4]. Being the only way of removing P from oceanic water, sedimentary P burial is one of the most important processes during biogeochemical cycling of P. The high concentrations of organic matter and pronounced microbial activity at ODP Site 1230 along the Peru Margin result in unusually high interstitial water phosphate concentrations, which provides a unique opportunity to use δ18OP to investigate inorganic phosphate (Pi) regeneration and P cycling pathways in marine sediments. The isotopic measurements of both dissolved inorganic phosphate (DIP) and bulk sediment Pi show that DIP δ18OP values are affected by three different processes, which are all induced by specific microbial activities present in the sediments. In sediments at ~ 65 to 120 mbsf, porewater DIP is derived from dissolved organophosphorus compounds (DOP) through enzymatic degradation pathways, evidenced by both DIP δ18OP values and interstitial water chemistry. Measured porewater DIP δ18OP values also suggest that 4 to 8% of interstitial water DIP reflects regeneration of Pi from Porg by microbially-synthesized enzymes. Throughout the sediment column and especially at ~ 120 to 150 mbsf, DIP is released from the sediments by microbially-induced reductive dissolution of Fe-oxides, which contributes to the overall high DIP concentrations at Site 1230. The third and dominant process controlling measured DIP δ18OP values is microbial turnover of regenerated Pi. The presence of high microbial activities in organic-rich Site 1230 sediments promotes the remobilization of P and affects marine P cycling by potentially enhancing

  13. Phytic Acid Synthesis and Vacuolar Accumulation in Suspension-Cultured Cells of Catharanthus roseus Induced by High Concentration of Inorganic Phosphate and Cations1[w

    PubMed Central

    Mitsuhashi, Naoto; Ohnishi, Miwa; Sekiguchi, Yoko; Kwon, Yong-Uk; Chang, Young-Tae; Chung, Sung-Kee; Inoue, Yoshinori; Reid, Robert J.; Yagisawa, Hitoshi; Mimura, Tetsuro

    2005-01-01

    We have established a new system for studying phytic acid, myo-inositol hexakisphosphate (InsP6) synthesis in suspension-cultured cells of Catharanthus. InsP6 and other intermediates of myo-inositol (Ins) phosphate metabolism were measured using an ion chromatography method. The detection limit for InsP6 was less than 50 nm, which was sufficient to analyze Ins phosphates in living cells. Synthesis of Ins phosphates was induced by incubation in high inorganic phosphate medium. InsP6 was mainly accumulated in vacuoles and was enhanced when cells were grown in high concentration of inorganic phosphates with the cations K+, Ca2+, or Zn2+. However, there was a strong tendency for InsP6 to accumulate in the vacuole in the presence of Ca2+ and in nonvacuolar compartments when supplied with Zn2+, possibly due to precipitation of InsP6 with Zn2+ in the cytosol. A vesicle transport inhibitor, brefeldin A, stimulated InsP6 accumulation. The amounts of both Ins(3)P1 myo-inositol monophosphate synthase, a key enzyme for InsP6 synthesis, and Ins(1,4,5)P3 kinase were unrelated to the level of accumulation of InsP6. The mechanisms for InsP6 synthesis and localization into vacuoles in plant cells are discussed. PMID:15965017

  14. Hybrid organic-inorganic crystals based on ammonium dihydrogen phosphate and ammonium salicylate

    NASA Astrophysics Data System (ADS)

    Voronov, A. P.; Salo, V. I.; Puzikov, V. M.; Babenko, G. N.; Roshal, A. D.; Tkachenko, V. F.

    2011-11-01

    ADP-NH 4Sal hybrid crystals are grown from aqueous solutions. The influence of the acidity of the mixed solution on the conditions of co-crystallization of the components is studied. The spectral and scintillation characteristics are determined. Co-crystallization of ammonium salicylate (NH 4Sal) and ammonium dihydrogen phosphate (ADP, NH 4H 2PO 4) is shown to be feasible, the structure of the doping addition being defined by the solution рН. In basic and weak acidic media the hybrid crystals ADP:NH 4Sal are formed in which salicylate anions are located in the interplanar space between the {110}-type planes in the lattice of ADP. The luminescence spectra contain an emission band maximum with λ max=360 nm. In acidic solutions there are ADP:HSal crystals in which salicylic acid molecules captured by the growth macrosteps are located in the interplanar space of the prismatic {100} and pyramidal {101} growth sectors. The luminescence band undergoes bathochromic shift to λmax=400 nm. The sensitivity of ADP:NH 4Sal scintillation crystals to fast neutrons depends on the concentration of ammonium salicylate in ADP matrix. The highest neutron sensitivity is characteristic of the co-doped ADP:NH 4Sal/Tl scintillation crystals.

  15. Influence of an organic and an inorganic additive on the crystallization of dicalcium phosphate dihydrate

    NASA Astrophysics Data System (ADS)

    Anee, T. K.; Meenakshi Sundaram, N.; Arivuoli, D.; Ramasamy, P.; Narayana Kalkura, S.

    2005-12-01

    Dicalcium phosphate dihydrate (DCPD) was crystallized by single diffusion method under physiological pH, in the presence of cobalt and malic acid. The morphology, composition and microstructure of the grown crystals were analyzed using EDTA titration, UV-Visible, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM). These analyses showed that the grown crystals were Co 2+-doped DCPD. The temperature has influenced the dopant entry into DCPD crystals, but the dopant content and temperature were having not much influence on the crystal morphology. In pathological crystallization, the size and morphology are very important since they decide the mode of treatment to adopt. The morphological changes arise when the growth assay is doped with cobalt and malic acid. The effect of malic acid on the crystallization was highly specific, adsorbing on certain crystal faces during growth and producing different morphologies. At higher concentration, the morphology showed a feature frequently encountered in biomineralization, the orientational ordering in [0 0 1], leading to elongated crystals.

  16. Layered inorganic materials as redox agents: ferrocenium-intercalated zirconium phosphate.

    PubMed

    Santiago, Mitk'El B; Declet-Flores, Chasterie; Díaz, Agustín; Vélez, Meredith M; Bosques, Myrna Zoé; Sanakis, Yannis; Colón, Jorge L

    2007-07-03

    The direct intercalation reaction of ferrocene (bis(eta5-cyclopentadienyl)iron(II), Fc) with a highly hydrated layered zirconium phosphate (ZrP) resulted in the formation of the ferrocenium ion (Fc+) within the ZrP material. The Fc+-intercalated ZrP material has an interlayer distance of 10.7 A. The intercalated material was used as an electron acceptor for the oxidation of both ferro-cytochrome c and the excited state of tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)3]2+). Upon contact of the material with a 1.5 x 10(-5) M solution of ferro-cytochrome c, the UV-vis absorption spectrum shows the successful formation of ferri-cytochrome c. Luminescence spectroscopy shows that the Fc+-intercalated ZrP material quenches the luminescence of [Ru(bpy)3]2+. The excited-state quenching mechanism of [Ru(bpy)3]2+* by Fc+-intercalated ZrP follows a dynamic plus sphere of action model. The second-order dynamic quenching rate constant kq is 2.2 x 10(8) M(-1) s(-1).

  17. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    SciTech Connect

    Sugama, T.; Pyatina, T.

    2014-11-01

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  18. Inorganic Corrosion-Inhibitive Pigments for High-Temperature Alkali-activated Well Casing Foam Cement

    SciTech Connect

    Sugama, T.; Pyatina, T.

    2014-11-14

    This study evaluates inorganic pigments for improving carbon steel (CS) brine-corrosion protection by the sodium metasilicate-activated calcium aluminate cement/Fly Ash blend at 300°C. Calcium borosilicate (CBS) and zinc phosphate, significantly improved CS corrosion-protection by decreasing cement’s permeability for corrosive ions and inhibiting anodic corrosion. An amorphous Na2O-Al2O3-SiO2-H2O phase tightly attached to CS surface formed at 300oC in CBS-modified cement pore solution. The corrosion rate of the CS covered with this phase was nearly 4-fold lower than in the case of nonmodified cement pore solution where the major phase formed on the surface of CS was crystalline analcime.

  19. Proteomic Analysis Provides New Insights in Phosphorus Homeostasis Subjected to Pi (Inorganic Phosphate) Starvation in Tomato Plants (Solanum lycopersicum L.).

    PubMed

    Muneer, Sowbiya; Jeong, Byoung Ryong

    2015-01-01

    Phosphorus is a major nutrient acquired by plants via high-affinity inorganic phosphate (Pi) transporters. To determine the adaptation and homeostasis strategy to Pi starvation, we compared the proteome analysis of tomato leaves that were treated with and without Pi (as KH2PO4) for 10 days. Among 600 reproducible proteins on 2-DE gels 46 of them were differentially expressed. These proteins were involved in major metabolic pathways, including photosynthesis, transcriptional/translational regulations, carbohydrate/energy metabolism, protein synthesis, defense response, and other secondary metabolism. The results also showed that the reduction in photosynthetic pigments lowered P content under -Pi treatments. Furthermore, high-affinity Pi transporters (lePT1 and lePT2) expressed in higher amounts under -Pi treatments. Also, the accumulation of Pi transporters was observed highly in the epidermis and palisade parenchyma under +Pi treatments compared to -Pi treatments. Our data suggested that tomato plants developed reactive oxygen species (ROS) scavenging mechanisms to cope with low Pi content, including the up-regulation of proteins mostly involved in important metabolic pathways. Moreover, Pi-starved tomato plants increased their internal Pi utilization efficiency by increasing the Pi transporter genes and their rational localization. These results thus provide imperative information about how tomato plants respond to Pi starvation and its homeostasis.

  20. Proteomic Analysis Provides New Insights in Phosphorus Homeostasis Subjected to Pi (Inorganic Phosphate) Starvation in Tomato Plants (Solanum lycopersicum L.)

    PubMed Central

    Muneer, Sowbiya; Jeong, Byoung Ryong

    2015-01-01

    Phosphorus is a major nutrient acquired by plants via high-affinity inorganic phosphate (Pi) transporters. To determine the adaptation and homeostasis strategy to Pi starvation, we compared the proteome analysis of tomato leaves that were treated with and without Pi (as KH2PO4) for 10 days. Among 600 reproducible proteins on 2-DE gels 46 of them were differentially expressed. These proteins were involved in major metabolic pathways, including photosynthesis, transcriptional/translational regulations, carbohydrate/energy metabolism, protein synthesis, defense response, and other secondary metabolism. The results also showed that the reduction in photosynthetic pigments lowered P content under –Pi treatments. Furthermore, high-affinity Pi transporters (lePT1 and lePT2) expressed in higher amounts under –Pi treatments. Also, the accumulation of Pi transporters was observed highly in the epidermis and palisade parenchyma under +Pi treatments compared to –Pi treatments. Our data suggested that tomato plants developed reactive oxygen species (ROS) scavenging mechanisms to cope with low Pi content, including the up-regulation of proteins mostly involved in important metabolic pathways. Moreover, Pi-starved tomato plants increased their internal Pi utilization efficiency by increasing the Pi transporter genes and their rational localization. These results thus provide imperative information about how tomato plants respond to Pi starvation and its homeostasis. PMID:26222137

  1. Inactivation of highly activated spinach leaf sucrose-phosphate synthase by dephosphorylation. [Spinacia oleracea

    SciTech Connect

    Huber, J.L. ); Huber, S.C. North Carolina State Univ., Raleigh ); Hite, D.R.C.; Outlaw, W.H. Jr. )

    1991-01-01

    Spinach (Spinacia oleracea L.) leaf sucrose-phosphate synthase (SPS) can be phosphorylated and inactivated in vitro with ({gamma}-{sup 32}P)ATP. Thus, it was surprising to find that SPS, extracted from leaves fed mannose in the light to highly activate the enzyme, could be inactivated in an ATP-independent manner when desalted crude extracts were preincubated at 25{degrees}C before assay. The spontaneous inactivation involved a loss in activity measured with limiting substrate concentrations in the presence of the inhibitor, Pi, without affecting maximum catalytic activity. The spontaneous inactivation was unaffected by exogenous carrier proteins and protease inhibitors, but was inhibited by inorganic phosphate, fluoride, and molybdate, suggesting that a phosphatase may be involved. Okadaic acid, a potent inhibitor of mammalian type 1 and 2A protein phosphatases, had no effect up to 5 micromolar. Inactivation was stimulated about twofold by exogenous Mg{sup 2+} and was relatively insensitive to Ca{sup 2+} and to pH over the range pH 6.5 to 8.5. Radioactive phosphate incorporated into SPS during labeling of excised leaves with ({sup 32}P)Pi (initially in the dark and then in the light with mannose) was lost with time when desalted crude extracts were incubated at 25 C, and the loss in radiolabel was substantially reduced by fluoride. These results provide direct evidence for action of an endogenous phosphatase(s) using SPS as substrate.

  2. Structural basis for glucose-6-phosphate activation of glycogen synthase

    SciTech Connect

    Baskaran, Sulochanadevi; Roach, Peter J.; DePaoli-Roach, Anna A.; Hurley, Thomas D.

    2010-11-22

    Regulation of the storage of glycogen, one of the major energy reserves, is of utmost metabolic importance. In eukaryotes, this regulation is accomplished through glucose-6-phosphate levels and protein phosphorylation. Glycogen synthase homologs in bacteria and archaea lack regulation, while the eukaryotic enzymes are inhibited by protein kinase mediated phosphorylation and activated by protein phosphatases and glucose-6-phosphate binding. We determined the crystal structures corresponding to the basal activity state and glucose-6-phosphate activated state of yeast glycogen synthase-2. The enzyme is assembled into an unusual tetramer by an insertion unique to the eukaryotic enzymes, and this subunit interface is rearranged by the binding of glucose-6-phosphate, which frees the active site cleft and facilitates catalysis. Using both mutagenesis and intein-mediated phospho-peptide ligation experiments, we demonstrate that the enzyme's response to glucose-6-phosphate is controlled by Arg583 and Arg587, while four additional arginine residues present within the same regulatory helix regulate the response to phosphorylation.

  3. Effects of inorganic phosphate analogues on stiffness and unloaded shortening of skinned muscle fibres from rabbit.

    PubMed

    Chase, P B; Martyn, D A; Kushmerick, M J; Gordon, A M

    1993-01-01

    1. We examined the effects of aluminofluoride (AlFx) and orthovanadate (Vi), tightly binding analogues of orthophosphate (Pi), on the mechanical properties of glycerinated fibres from rabbit psoas muscle. Maximum Ca(2+)-activated force, stiffness, and unloaded shortening velocity (Vus) were measured under conditions of steady-state inhibition (up to 1 mM of inhibitor) and during the recovery from inhibition. 2. Stiffness was measured using either step or sinusoidal (1 kHz) changes in fibre length. Sarcomere length was monitored continuously by helium-neon laser diffraction during maximum Ca2+ activation. Stiffness was determined from the changes in sarcomere length and the corresponding changes in force. Vus was measured using the slack test method. 3. AlF chi and Vi each reversibly inhibited force, stiffness and Vus. Actively cycling cross-bridges were required for reversal of these inhibitory effects. Recovery from inhibition by AlF chi was 3- to 4-fold slower than that following removal of V1. 4. At various degrees of inhibition, AlF chi and Vi both inhibited steady-state isometric force more than either Vus or stiffness. For both AlF chi and Vi, the relatively greater inhibition of force over stiffness persisted during recovery from steady-state inhibition. We interpret these results to indicate that the cross-bridges with AlF chi or Vi bound are analogous to those which occur early in the cross-bridge cycle.

  4. Effects of inorganic phosphate analogues on stiffness and unloaded shortening of skinned muscle fibres from rabbit.

    PubMed Central

    Chase, P B; Martyn, D A; Kushmerick, M J; Gordon, A M

    1993-01-01

    1. We examined the effects of aluminofluoride (AlFx) and orthovanadate (Vi), tightly binding analogues of orthophosphate (Pi), on the mechanical properties of glycerinated fibres from rabbit psoas muscle. Maximum Ca(2+)-activated force, stiffness, and unloaded shortening velocity (Vus) were measured under conditions of steady-state inhibition (up to 1 mM of inhibitor) and during the recovery from inhibition. 2. Stiffness was measured using either step or sinusoidal (1 kHz) changes in fibre length. Sarcomere length was monitored continuously by helium-neon laser diffraction during maximum Ca2+ activation. Stiffness was determined from the changes in sarcomere length and the corresponding changes in force. Vus was measured using the slack test method. 3. AlF chi and Vi each reversibly inhibited force, stiffness and Vus. Actively cycling cross-bridges were required for reversal of these inhibitory effects. Recovery from inhibition by AlF chi was 3- to 4-fold slower than that following removal of V1. 4. At various degrees of inhibition, AlF chi and Vi both inhibited steady-state isometric force more than either Vus or stiffness. For both AlF chi and Vi, the relatively greater inhibition of force over stiffness persisted during recovery from steady-state inhibition. We interpret these results to indicate that the cross-bridges with AlF chi or Vi bound are analogous to those which occur early in the cross-bridge cycle. PMID:8487194

  5. Enhancing Enzyme Activity and Immobilization in Nanostructured Inorganic-Enzyme Complexes.

    PubMed

    Lang, Xuye; Zhu, Lingling; Gao, Yingning; Wheeldon, Ian

    2017-09-12

    Understanding the chemical and physical interactions at the interface of protein surfaces and inorganic crystals has important implications in the advancement of immobilized enzyme catalysis. Recently, enzyme-inorganic hybrid complexes have been demonstrated as effective materials for enzyme immobilization. The precipitation of phosphate nanocrystals in the presence of enzymes creates enzyme-Cu3(PO4)2·3H2O particles with high surface-to-volume ratios, enhanced activity, and increased stability. Here, we begin to develop a mechanistic understanding of enzyme loading in such complexes. Using a series of enzymes including horseradish peroxidase (HRP), a thermostable alcohol dehydrogenase (AdhD), diaphorase, catalase, glucose oxidase (GOx), and the protein bovine serum albumin (BSA), we identified a correlation between particle synthesis temperature, overall enzyme charge, and enzyme loading. The model enzyme HRP has a high predicted pI of ∼7.5 and maintains an overall positive charge under the synthesis conditions, phosphate buffer pH 7.4. HRP loading in HRP-Cu3(PO4)2 complexes was enhanced by 4.2-fold when synthesis was carried out at 37 °C in comparison with synthesis at 4 °C. HRP loading was further enhanced with synthesis at pH 8.0, correlating with a decrease in overall enzyme charge. Proteins with lower predicted pI values and negative overall charge (AdhD, pI of 5.6; diaphorase, pI of 6.8; GOx, pI of 5.2; catalase, pI of 6.9; and, BSA, pI of 5.7) exhibited higher enzyme loadings with 4 °C synthesis, 2.7-, 2.6-, 2.5-, 1.8-, and 1.7-fold protein loading enhancements, respectively. Using HRP as a model system, we also demonstrate that activity increased concomitantly with enzyme loading, and that particle nanostructure was minimally affected by synthesis temperature. Combined, the results presented here demonstrate the control of enzyme loading in enzyme-inorganic particles opening up new possibilities in enzyme and multienzyme catalysis.

  6. Association of serum inorganic phosphate with sex steroid hormones and vitamin D in a nationally representative sample of men

    PubMed Central

    Wulaningsih, W.; Van Hemelrijck, M.; Michaelsson, K.; Kanarek, N.; Nelson, W. G.; Ix, J. H.; Platz, E. A.; Rohrmann, S.

    2015-01-01

    SUMMARY Defects in bone regulatory pathways have been linked to chronic diseases including cardiovascular disease and cancer. In men, a link between bone metabolism and gonadal hormones has been suggested. However, to date, there is lack of evidence on the association between serum inorganic phosphate (Pi) and sex steroid hormones. The objective of this study was to investigate the association between Pi, sex steroid hormones and a known Pi metabolic regulator, vitamin D, in men in the National Health and Nutrition Examination Survey III (NHANES III). From NHANES III, we selected 1412 men aged 20+ who participated in the morning session of Phase I (1988–1991) with serum measurements of Pi, sex hormones, and vitamin D. Multivariable linear regression was used to calculate crude and geometric mean Pi by total and estimated free testosterone and estradiol, sex hormone-binding globulin, androstanediol glucuronide (AAG), and vitamin D. Similar analyses were performed while stratifying by race/ethnicity and vitamin D levels. We found a lack of statistically significant difference in geometric means of Pi across quintiles of concentrations of sex hormones, indicating a tight regulation of Pi. However, Pi levels were inversely associated with calculated free testosterone in non-Hispanic black men, with geometric mean levels of Pi of 1.16 and 1.02 ng/mL for those in the lowest and highest quintiles of free testosterone, respectively (p-trend < 0.05). A similar but weaker pattern was seen between total testosterone and Pi. An inverse association was also seen between AAG and Pi in men with vitamin D concentration below the median (<24.2 ng/mL). No associations were observed among men with vitamin D levels at or above the median. Our findings suggest a weak link among sex hormones, vitamin D, and Pi in men. The observed effects of race/ethnicity and vitamin D indicate a complex association involving various regulators of Pi homeostasis. PMID:25270590

  7. Association of serum inorganic phosphate with sex steroid hormones and vitamin D in a nationally representative sample of men.

    PubMed

    Wulaningsih, W; Van Hemelrijck, M; Michaelsson, K; Kanarek, N; Nelson, W G; Ix, J H; Platz, E A; Rohrmann, S

    2014-11-01

    Defects in bone regulatory pathways have been linked to chronic diseases including cardiovascular disease and cancer. In men, a link between bone metabolism and gonadal hormones has been suggested. However, to date, there is lack of evidence on the association between serum inorganic phosphate (Pi) and sex steroid hormones. The objective of this study was to investigate the association between Pi, sex steroid hormones and a known Pi metabolic regulator, vitamin D, in men in the National Health and Nutrition Examination Survey III (NHANES III). From NHANES III, we selected 1412 men aged 20+ who participated in the morning session of Phase I (1988-1991) with serum measurements of Pi, sex hormones, and vitamin D. Multivariable linear regression was used to calculate crude and geometric mean Pi by total and estimated free testosterone and estradiol, sex hormone-binding globulin, androstanediol glucuronide (AAG), and vitamin D. Similar analyses were performed while stratifying by race/ethnicity and vitamin D levels. We found a lack of statistically significant difference in geometric means of Pi across quintiles of concentrations of sex hormones, indicating a tight regulation of Pi. However, Pi levels were inversely associated with calculated free testosterone in non-Hispanic black men, with geometric mean levels of Pi of 1.16 and 1.02 ng/mL for those in the lowest and highest quintiles of free testosterone, respectively (p-trend < 0.05). A similar but weaker pattern was seen between total testosterone and Pi. An inverse association was also seen between AAG and Pi in men with vitamin D concentration below the median (<24.2 ng/mL). No associations were observed among men with vitamin D levels at or above the median. Our findings suggest a weak link among sex hormones, vitamin D, and Pi in men. The observed effects of race/ethnicity and vitamin D indicate a complex association involving various regulators of Pi homeostasis.

  8. Inorganic phosphate induces cancer cell mediated angiogenesis dependent on forkhead box protein C2 (FOXC2) regulated osteopontin expression.

    PubMed

    Lin, Yiming; McKinnon, Kelly E; Ha, Shin Woo; Beck, George R

    2015-09-01

    Recent studies in both rodents and humans suggest that elevated serum phosphorus, in the context of normal renal function, potentiates, or exacerbates pathologies associates with cardiovascular disease, bone metabolism, and cancer. Our recent microarray studies identified the potent stimulation of pro-angiogenic genes such as forkhead box protein C2 (FOXC2), osteopontin, and Vegfα, among others in response to elevated inorganic phosphate (Pi). Increased angiogenesis and neovascularization are important events in tumor growth and the progression to malignancy and FOXC2 has recently been identified as a potential transcriptional regulator of these processes. In this study we addressed the possibility that a high Pi environment would increase the angiogenic potential of cancer cells through a mechanism requiring FOXC2. Our studies utilized lung and breast cancer cell lines in combination with the human umbilical vascular endothelial cell (HUVEC) vessel formation model to better understand the mechanism(s) by which a high Pi environment might alter cancer progression. Exposure of cancer cells to elevated Pi stimulated expression of FOXC2 and conditioned medium from the Pi-stimulated cancer cells stimulated migration and tube formation in the HUVEC model. Mechanistically, we define the requirement of FOXC2 for Pi-induced osteopontin (OPN) expression and secretion from cancer cells as necessary for the angiogenic response. These studies reveal for the first time that cancer cells grown in a high Pi environment promote migration of endothelial cells and tube formation and in so doing identify a novel potential therapeutic target to reduce tumor progression.

  9. Differential Effects of Indoxyl Sulfate and Inorganic Phosphate in a Murine Cerebral Endothelial Cell Line (bEnd.3)

    PubMed Central

    Stinghen, Andréa E. M.; Chillon, Jean-Marc; Massy, Ziad A.; Boullier, Agnès

    2014-01-01

    Endothelial dysfunction plays a key role in stroke in chronic kidney disease patients. To explore the underlying mechanisms, we evaluated the effects of two uremic toxins on cerebral endothelium function. bEnd.3 cells were exposed to indoxyl sulfate (IS) and inorganic phosphate (Pi). Nitric oxide (NO), reactive oxygen species (ROS) and O2•– were measured using specific fluorophores. Peroxynitrite and eNOS uncoupling were evaluated using ebselen, a peroxide scavenger, and tetrahydrobiopterin (BH4), respectively. Cell viability decreased after IS or Pi treatment (p < 0.01). Both toxins reduced NO production (IS, p < 0.05; Pi, p < 0.001) and induced ROS production (p < 0.001). IS and 2 mM Pi reduced O2•– production (p < 0.001). Antioxidant pretreatment reduced ROS levels in both IS- and Pi-treated cells, but a more marked reduction of O2•– production was observed in Pi-treated cells (p < 0.001). Ebselen reduced the ROS production induced by the two toxins (p < 0.001); suggesting a role of peroxynitrite in this process. BH4 addition significantly reduced O2•– and increased NO production in Pi-treated cells (p < 0.001), suggesting eNOS uncoupling, but had no effect in IS-treated cells. This study shows, for the first time, that IS and Pi induce cerebral endothelial dysfunction by decreasing NO levels due to enhanced oxidative stress. However, Pi appears to be more deleterious, as it also induces eNOS uncoupling. PMID:24902077

  10. Inorganic Phosphate Accelerates the Migration of Vascular Smooth Muscle Cells: Evidence for the Involvement of miR-223

    PubMed Central

    Metzinger-Le Meuth, Valérie; Hénaut, Lucie; Djelouat, Mohamed Seif el Islam; Benchitrit, Joyce; Massy, Ziad A.; Metzinger, Laurent

    2012-01-01

    Backgound An elevated serum inorganic phosphate (Pi) level is a major risk factor for kidney disease and downstream vascular complications. We focused on the effect of Pi levels on human aortic vascular smooth muscle cells (VSMCs), with an emphasis on the role of microRNAs (miRNAs). Methodology/Principal Findings Exposure of human primary VSMCs in vitro to pathological levels of Pi increased calcification, migration rate and concomitantly reduced cell proliferation and the amount of the actin cytoskeleton. These changes were evidenced by significant downregulation of miRNA-143 (miR-143) and miR-145 and concomitant upregulation of their targets and key markers in synthetic VSMCs, such as Krüppel-like factors−4 and −5 and versican. Interestingly, we also found that miR-223 (a marker of muscle damage and a key factor in osteoclast differentiation) is expressed in VSMCs and is significantly upregulated in Pi-treated cells. Over-expressing miR-223 in VSMCs increased proliferation and markedly enhanced VSMC migration. Additionally, we found that the expression of two of the known miR-223 targets, Mef2c and RhoB, was highly reduced in Pi treated as well as miR-223 over-expressing VSMCs. To complement these in vitro findings, we also observed significant downregulation of miR-143 and miR-145 and upregulation of miR-223 in aorta samples collected from ApoE knock-out mice, which display vascular calcification. Conclusions/Significance Our results suggest that (i) high levels of Pi increase VSMC migration and calcification, (ii) altered expression levels of miR-223 could play a part in this process and (iii) miR-223 is a potential new biomarker of VSMC damage. PMID:23094093

  11. Inactivation of Highly Activated Spinach Leaf Sucrose-Phosphate Synthase by Dephosphorylation 1

    PubMed Central

    Huber, Joan L.; Hite, Daniel R. C.; Outlaw, William H.; Huber, Steven C.

    1991-01-01

    Spinach (Spinacia oleracea L.) leaf sucrose-phosphate synthase (SPS) can be phosphorylated and inactivated in vitro with [γ-32P]ATP (JLA Huber, SC Huber, TH Nielsen [1989] Arch Biochem Biophys 270: 681-690). Thus, it was surprising to find that SPS, extracted from leaves fed mannose in the light to highly activate the enzyme, could be inactivated in an ATP-independent manner when desalted crude extracts were preincubated at 25°C before assay. The “spontaneous” inactivation involved a loss in activity measured with limiting substrate concentrations in the presence of the inhibitor, Pi, without affecting maximum catalytic activity. The spontaneous inactivation was unaffected by exogenous carrier proteins and protease inhibitors, but was inhibited by inorganic phosphate, fluoride, and molybdate, suggesting that a phosphatase may be involved. Okadaic acid, a potent inhibitor of mammalian type 1 and 2A protein phosphatases, had no effect up to 5 micromolar. Inactivation was stimulated about twofold by exogenous Mg2+ and was relatively insensitive to Ca2+ and to pH over the range pH 6.5 to 8.5. Radioactive phosphate incorporated into SPS during labeling of excised leaves with [32P]Pi (initially in the dark and then in the light with mannose) was lost with time when desalted crude extracts were incubated at 25°C, and the loss in radiolabel was substantially reduced by fluoride. These results provide direct evidence for action of an endogenous phosphatase(s) using SPS as substrate. We postulate that highly activated SPS contains phosphorylated residue(s) that increase activation state, and that spontaneous inactivation occurs by removal of these phosphate group(s). Inactivation of SPS in vivo caused by feeding uncouplers to darkened leaf tissue that had previously been fed mannose in the dark, may occur by this mechanism. However, there is no evidence that this mechanism is involved in light-dark regulation of SPS in vivo. PMID:16667968

  12. Ca2+ uptake, Ca2+-ATPase activity, phosphoprotein formation and phosphate turnover in a microsomal fraction of smooth muscle.

    PubMed

    Raeymaekers, L; Hasselbach, W

    1981-05-15

    Vesicles capable of phosphate-stimulated calcium uptake were isolated from the microsomal fraction of the smooth muscle of the pig stomach according to a previously described procedure which consists in increasing the density of the vesicles by loading them with calcium phosphate and isolating them by centrifugation [Raeymaekers, L., Agostini, B., and Hasselbach, W. (1981) Histochemistry, 70, 139--150]. These vesicles, which contain calcium phosphate deposits, are able to accumulate an additional amount of calcium. This calcium uptake is accompanied by calcium-stimulated ATPase activity and by the formation of an acid-stable phosphoprotein. The acid-denatured phosphoprotein is dephosphorylated by hydroxylamine, which indicates that an acylphosphate is formed. This phosphoprotein probably represents a phosphorylated transport intermediate similar to that seen with the Ca2+-ATPase of sarcoplasmic reticulum of skeletal muscle. As with the Ca2+-ATPase of sarcoplasmic reticulum vesicles, this vesicular fraction catalyses an exchange between inorganic phosphate and the gamma-phosphate of ATP (ATP-Pi exchange) which is dependent on the presence of intravesicular calcium, and an exchange of phosphate between ATP and ADP (ATP-ADP exchange). The results further indicate that the turnover rate of the calcium pump, calculated from the ratio of calcium-stimulated ATPase activity to the steady-state level of phosphoprotein, is similar to that of Ca2+-ATPase of sarcoplasmic reticulum of skeletal muscle.

  13. Phosphate-Modified Nucleotides for Monitoring Enzyme Activity.

    PubMed

    Ermert, Susanne; Marx, Andreas; Hacker, Stephan M

    2017-04-01

    Nucleotides modified at the terminal phosphate position have been proven to be interesting entities to study the activity of a variety of different protein classes. In this chapter, we present various types of modifications that were attached as reporter molecules to the phosphate chain of nucleotides and briefly describe the chemical reactions that are frequently used to synthesize them. Furthermore, we discuss a variety of applications of these molecules. Kinase activity, for instance, was studied by transfer of a phosphate modified with a reporter group to the target proteins. This allows not only studying the activity of kinases, but also identifying their target proteins. Moreover, kinases can also be directly labeled with a reporter at a conserved lysine using acyl-phosphate probes. Another important application for phosphate-modified nucleotides is the study of RNA and DNA polymerases. In this context, single-molecule sequencing is made possible using detection in zero-mode waveguides, nanopores or by a Förster resonance energy transfer (FRET)-based mechanism between the polymerase and a fluorophore-labeled nucleotide. Additionally, fluorogenic nucleotides that utilize an intramolecular interaction between a fluorophore and the nucleobase or an intramolecular FRET effect have been successfully developed to study a variety of different enzymes. Finally, also some novel techniques applying electron paramagnetic resonance (EPR)-based detection of nucleotide cleavage or the detection of the cleavage of fluorophosphates are discussed. Taken together, nucleotides modified at the terminal phosphate position have been applied to study the activity of a large diversity of proteins and are valuable tools to enhance the knowledge of biological systems.

  14. Development of an engineered soil bacterium enabling to convert both insoluble inorganic and organic phosphate into plant available phosphate and its use as a biofertilizer.

    PubMed

    Liu, Lili; Du, Wenya; Luo, Wenyu; Su, Yi; Hui, Jiejie; Ma, Shengwu

    2015-05-01

    Phosphorus (P) is one of the most important nutrient elements for plant growth and metabolism. We previously isolated a P-solubilizing bacterium 9320-SD with the ability to utilize inorganic P and convert it into plant-available P. The present study aims to enhance the P-solubilizing capacity of 9320-SD, as our long-term goal is to develop a more effective P-solubilizing bacterial strain for use as a biofertilizer. In this end, we introduced a bacterial phytase encoding gene into 9320-SD. One randomly selected transformant, SDLiuTP02, was examined for recombinant protein expression and phytase activity, and assessed for its ability to promote plant growth. Our results indicate that SDLiuTP02 is capable of expressing high levels of phytase activity. Importantly, corn seedlings treated with the SDLiuTP02 cell culture exhibited increased rates of photosynthesis, transpiration, and stomatal conductance as well as increased growth rate under laboratory conditions and increased growth rate in pot assays compared to seedlings treated with cell cultures of the parental strain 9320-SD. Field experiments further indicated that application of SDLiuTP02 promoted a greater growth rate in young cucumber plant and a higher foliar chlorophyll level in chop suey greens when compared to 9320-SD treated controls. These results indicate that SDLiuTP02 has the potential to be a more effective P biofertilizer to increase agricultural productivity.

  15. Phosphate oxygen isotopic evidence for a temperate and biologically active Archaean ocean.

    PubMed

    Blake, Ruth E; Chang, Sae Jung; Lepland, Aivo

    2010-04-15

    Oxygen and silicon isotope compositions of cherts and studies of protein evolution have been interpreted to reflect ocean temperatures of 55-85 degrees C during the early Palaeoarchaean era ( approximately 3.5 billion years ago). A recent study combining oxygen and hydrogen isotope compositions of cherts, however, makes a case for Archaean ocean temperatures being no greater than 40 degrees C (ref. 5). Ocean temperature can also be assessed using the oxygen isotope composition of phosphate. Recent studies show that (18)O:(16)O ratios of dissolved inorganic phosphate (delta(18)O(P)) reflect ambient seawater temperature as well as biological processing that dominates marine phosphorus cycling at low temperature. All forms of life require and concentrate phosphorus, and as a result of biological processing, modern marine phosphates have delta(18)O(P) values typically between 19-26 per thousand (VSMOW), highly evolved from presumed source values of approximately 6-8 per thousand that are characteristic of apatite in igneous rocks and meteorites. Here we report oxygen isotope compositions of phosphates in sediments from the 3.2-3.5-billion-year-old Barberton Greenstone Belt in South Africa. We find that delta(18)O(P) values range from 9.3 per thousand to 19.9 per thousand and include the highest values reported for Archaean rocks. The temperatures calculated from our highest delta(18)O(P) values and assuming equilibrium with sea water with delta(18)O = 0 per thousand (ref. 12) range from 26 degrees C to 35 degrees C. The higher delta(18)O(P) values are similar to those of modern marine phosphate and suggest a well-developed phosphorus cycle and evolved biologic activity on the Archaean Earth.

  16. EFFECT OF INORGANIC CATIONS ON BACTERICIDAL ACTIVITY OF ANIONIC SURFACTANTS

    PubMed Central

    Voss, J. G.

    1963-01-01

    Voss, J. G. (Procter & Gamble Co., Cincinnati, Ohio). Effect of inorganic cations on bactericidal activity of anionic surfactants. J. Bacteriol. 86:207–211. 1963.—The bactericidal effectiveness of two alkyl benzene sulfonates and of three other types of anionic surfactants against Staphylococcus aureus is increased in the presence of low concentrations of divalent cations, especially alkaline earths and metals of group IIB of the periodic table. The cations may act by decreasing the negative charge at the cell surface and increasing adsorption of the surfactant anions, leading to damage to the cytoplasmic membrane and death of the cell. Increased adsorption of surfactant is also found with Escherichia coli, but does not lead to death of the cell. PMID:14058942

  17. Vesicular-arbuscular mycorrhizae and the enzymatic utilization of inorganic phosphate by plant roots: Progress report 1985

    SciTech Connect

    Marx, D. H.

    1985-01-01

    It is well known that phosphorus absorption, especially from soil with low phosphorus levels, by plant roots can be enhanced by mycorrhizal infection. Root cortical cells colonized by vesicular-arbuscular mycorrhizal fungi (VAM) have higher concentrations of phosphorus than noninfected cells. Polyphosphate is the major phosphorus reserve in many fungi and is reported to be present abundantly in young and proliferating arbuscules. We propose that mycorrhizal polyphosphate can be utilized by the VAM-plant symbiont system as a phosphorus donor and an energy source in the glycolytic pathway, possibly after being hydrolyzed to pytrophosphate (PPi). The VAM systems of infected and noninfected roots of sweetgum (Liquidambar styraciflua L.) and onion (Allium cepa L. var. Texas Grand) were used to compare the activity of PPI-dependent phosphofructokinase (PFK), an enzyme utilizing PPi to convert frutose-6-phosphate into fructosel,6-bisphosphate. The ATP-PKF activity was measured also. 1 fig., 3 tabs.

  18. Quantitative cytochemical measurement of glyceraldehyde 3-phosphate dehydrogenase activity.

    PubMed

    Henderson, B

    1976-08-25

    A system has been developed for the quantitative measurment of glyceraldehyde 3-phosphate dehydrogenase activity in tissue sections. An obstacle to the histochemical study of this enzyme has been the fact that the substrate, gylceraldehyde 3-phosphate, is very unstable. In the present system a stable compound, fructose 1, 6-diphosphate, is used as the primary substrate and the demonsatration of the glyceraldehyde 3-phosphate dehydrogenase activity depends on the conversion of this compound into the specific substrate by the aldolase present in the tissue. The characteristics of the dehydrogenase activity resulting from the addition of fructose 1, 6-diphosphate, resemble closely the known properties of purified glyceraldehyde 3-phosphate dehydrogenase. Use of polyvinyl alcohol in the reaction medium prevents release of enzymes from the sections, as occurs in aqueous media. Although in this study intrinsic aldolase activity was found to be adequate for the rapid conversion of fructose 1, 6-diphosphate into the specific substrate for the dehydrogenase, the use of exogenous aldolase may be of particular advantage in assessing the intergrity of the Embden-Meyerhof pathway.

  19. Catalysis of hydrolysis and nucleophilic substitution at the P-N bond of phosphoimidazolide-activated nucleotides in phosphate buffers

    NASA Technical Reports Server (NTRS)

    Kanavarioti, A.; Rosenbach, M. T.

    1991-01-01

    Phosphoimidazolide-activated derivatives of guanosine and cytidine 5'-monophosphates, henceforth called ImpN's, exhibit enhanced rates of degradation in the presence of aqueous inorganic phosphate in the range 4.0 < or = pH < or = 8.6. This degradation is been attributed to (i) nucleophilic substitution of the imidazolide and (ii) catalysis of the P-N bond hydrolysis by phosphate. The first reaction results in the formation of nucleoside 5'-diphosphate and the second in nucleoside 5'-monophosphate. Analysis of the observed rates as well as the product ratios as a function of pH and phosphate concentration allow distinction between various mechanistic possibilities. The results show that both H2PO4- and HPO4(2-) participate in both hydrolysis and nucleophilic substitution. Statistically corrected biomolecular rate constants indicate that the dianion is 4 times more effective as a general base than the monoanion, and 8 times more effective as nucleophile. The low Bronsted value beta = 0.15 calculated for these phosphate species, presumed to act as general bases in facilitating water attack, is consistent with the fact that catalysis of the hydrolysis of the P-N bond in ImpN's has not been detected before. The beta nuc = 0.35 calculated for water, H2PO4-, HPO4(2-), and hydroxide acting as nucleophiles indicates a more associative transition state for nucleotidyl (O2POR- with R = nucleoside) transfers than that observed for phosphoryl (PO3(2-)) transfers (beta nuc = 0.25). With respect to the stability/reactivity of ImpN's under prebiotic conditions, our study shows that these materials would not suffer additional degradation due to inorganic phosphate, assuming the concentrations of phosphate, Pi, on prebiotic Earth were similar to those in the present oceans ([Pi] approximately 2.25 micromoles).

  20. Catalysis of hydrolysis and nucleophilic substitution at the P-N bond of phosphoimidazolide-activated nucleotides in phosphate buffers

    NASA Technical Reports Server (NTRS)

    Kanavarioti, A.; Rosenbach, M. T.

    1991-01-01

    Phosphoimidazolide-activated derivatives of guanosine and cytidine 5'-monophosphates, henceforth called ImpN's, exhibit enhanced rates of degradation in the presence of aqueous inorganic phosphate in the range 4.0 < or = pH < or = 8.6. This degradation is been attributed to (i) nucleophilic substitution of the imidazolide and (ii) catalysis of the P-N bond hydrolysis by phosphate. The first reaction results in the formation of nucleoside 5'-diphosphate and the second in nucleoside 5'-monophosphate. Analysis of the observed rates as well as the product ratios as a function of pH and phosphate concentration allow distinction between various mechanistic possibilities. The results show that both H2PO4- and HPO4(2-) participate in both hydrolysis and nucleophilic substitution. Statistically corrected biomolecular rate constants indicate that the dianion is 4 times more effective as a general base than the monoanion, and 8 times more effective as nucleophile. The low Bronsted value beta = 0.15 calculated for these phosphate species, presumed to act as general bases in facilitating water attack, is consistent with the fact that catalysis of the hydrolysis of the P-N bond in ImpN's has not been detected before. The beta nuc = 0.35 calculated for water, H2PO4-, HPO4(2-), and hydroxide acting as nucleophiles indicates a more associative transition state for nucleotidyl (O2POR- with R = nucleoside) transfers than that observed for phosphoryl (PO3(2-)) transfers (beta nuc = 0.25). With respect to the stability/reactivity of ImpN's under prebiotic conditions, our study shows that these materials would not suffer additional degradation due to inorganic phosphate, assuming the concentrations of phosphate, Pi, on prebiotic Earth were similar to those in the present oceans ([Pi] approximately 2.25 micromoles).

  1. A predictive model for the reactor inorganic suspended solids concentration in activated sludge systems.

    PubMed

    Ekama, G A; Wentzel, M C

    2004-11-01

    A simple predictive model for the activated sludge reactor inorganic suspended solids (ISS) concentration (excluding that from chemical precipitant dosing) is presented. It is based on the accumulation of influent ISS in the reactor and an ordinary heterotrophic organism (OHO) ISS content (fiOHO) of 0.15 mg ISS/mg OHO organic (volatile) suspended solids (VSS) and a variable phosphate accumulating organism (PAO) ISS content (fiPAO) proportional to their P content (fXBGP). Organism ISS content is conceptualized as the uptake of dissolved inorganic solids by active organisms, which when dried in the total suspended solids (TSS) test procedure, precipitate and manifest as ISS. The model is validated with data from 22 investigations conducted over the past 15 years on 30 aerobic and anoxic-aerobic nitrification-denitrification (ND) systems and 18 anaerobic-anoxic-aerobic ND biological excess P removal (BEPR) systems variously fed artificial and real wastewater, and operated from 3 to 20 days sludge age. The predicted reactor VSS/TSS ratio reflects the observed relative sensitivity to sludge age, which is low, and to BEPR, which is high. To use the model for design, two parameters need to be known: (1) the influent ISS concentration, which is not commonly measured in wastewater characterization analyses and (2) the P content of PAOs (fXBGP), which can vary considerably depending on the extent of anoxic P uptake BEPR that takes place in the system. Some guidance on the measurement of influent ISS concentration and selection of the PAO P content to calculate the mixed liquor VSS/TSS ratio for design is given.

  2. Carbon and Nitrogen Sources Influence Tricalcium Phosphate Solubilization and Extracellular Phosphatase Activity by Talaromyces flavus.

    PubMed

    Stefanoni Rubio, P J; Godoy, M S; Della Mónica, I F; Pettinari, M J; Godeas, A M; Scervino, J M

    2016-01-01

    The aim of this work was to study phosphate (P) solubilization (and the processes involved in this event) by Talaromyces flavus (BAFC 3125) as a function of carbon and/or nitrogen sources. P solubilization was evaluated in NBRIP media supplemented with different carbon (glucose, sorbitol, sucrose, and fructose) and nitrogen (L-asparagine, urea, ammonium sulfate (AS), and ammonium nitrate (AN) combinations. The highest P solubilization was related to the highest organic acid production (especially gluconic acid) and pH drop for those treatments where glucose was present. Also P solubilization was higher when an inorganic nitrogen source was supplemented to the media when compared to an organic one. Although not being present an organic P source, phosphatase activity was observed. This shows that P mineralization and P solubilization can occur simultaneously, and that P mineralization is not induced by the enzyme substrate. The combination that showed highest P solubilization was for AN-glucose. The highest acid phosphatase activity was for AS-fructose, while for alkaline phosphatase were for AS-fructose and AN-fructose. Acid phosphatase activity was higher than alkaline. P solubilization and phosphatase activity (acid and alkaline) were influenced by the different carbon-nitrogen combinations. A better understanding of phosphate-solubilizing fungi could bring a better use of soil P.

  3. Glycerolipid biosynthesis in Saccharomyces cerevisiae: sn-glycerol-3-phosphate and dihydroxyacetone phosphate acyltransferase activities.

    PubMed Central

    Schlossman, D M; Bell, R M

    1978-01-01

    Yeast acyl-coenzyme A:dihydroxyacetone-phosphate O-acyltransferase (DHAP acyltransferase; EC 2.3.1.42) was investigated to (i) determine whether its activity and that of acyl-coenzyme A:sn-glycerol-3-phosphate O-acyltransferase (glycerol-P acyltransferase; EC 2.3.1.15) represent dual catalytic functions of a single membranous enzyme, (ii) estimate the relative contributions of the glycerol-P and DHAP pathways for yeast glycerolipid synthesis, and (iii) evaluate the suitability of yeast for future genetic investigations of the eucaryotic glycerol-P and DHAP acyltransferase activities. The membranous DHAP acyltransferase activity showed an apparent Km of 0.79 mM for DHAP, with a Vmax of 5.3 nmol/min per mg, whereas the glycerol-P acyltransferase activity showed an apparent Km of 0.05 mM for glycerol-P, with a Vmax of 3.4 nmol/min per mg. Glycerol-P was a competitive inhibitor (Ki, 0.07 mM) of the DHAP acyltransferase activity, and DHAP was a competitive inhibitor (Ki, 0.91 mM) of the glycerol-P acyltransferase activity. The two acyltransferase activities exhibited marked similarities in their pH dependence, acyl-coenzyme A chain length preference and substrate concentration dependencies, thermolability, and patterns of inactivation by N-ethylmaleimide, trypsin, and detergents. Thus, the data strongly suggest that yeast glycerol-P and DHAP acyltransferase activities represent dual catalytic functions of a single membrane-bound enzyme. Furthermore, since no acyl-DHAP oxidoreductase activity could be detected in yeast membranes, the DHAP pathway for glycerolipid synthesis may not operate in yeast. PMID:25265

  4. Effects of pH and inorganic phosphate on force production in alpha-toxin-permeabilized isolated rat uterine smooth muscle.

    PubMed Central

    Crichton, C A; Taggart, M J; Wray, S; Smith, G L

    1993-01-01

    1. Strips of longitudinal smooth muscle isolated from rat uterus were permeabilized using crude alpha-toxin from the bacterium Staphylococcus aureus. This treatment rendered the surface membrane permeable to small molecular weight substances. Simultaneous measurements of tension and calcium concentration ([Ca2+]) (using indo-1 fluorescence) were used to investigate the effects of pH and inorganic phosphate concentration ([Pi]) on Ca(2+)-activated force generated by the contractile proteins. 2. Raising the [Pi] from 1 to 11 mM at a pH of 7.2 depressed both maximal and submaximal Ca(2+)-activated force. This effect of Pi was concentration dependent having the majority of its effect by 6 mM. 3. Further experiments at a submaximal [Ca2+] showed that Ca(2+)-activated force was enhanced by raising [Pi] from 6 to 11 mM suggesting that Pi increased the Ca2+ sensitivity of tension production. Based on these results, calculations indicate that the apparent affinity constant of Ca2+ for the contractile proteins increased from 4 x 10(6) M-1 to 6 x 10(6) M-1 on raising [Pi] from 1 to 11 mM. 4. Lowering pH from 7.2 to 6.7 at a [Pi] of 1 mM potentiated Ca(2+)-activated force with a small depression in the apparent Ca2+ sensitivity of tension production. This effect of pH on maximum (100 microM Ca2+) and submaximum (0.3 microM Ca2+) Ca(2+)-activated force was observed over a range of acidic pHs (7.0-6.7). 5. Increasing pH from 7.2 to 7.7 at a [Pi] of 1 mM depressed Ca(2+)-activated force with no effect on Ca2+ sensitivity of tension production. 6. Spontaneous contractions in intact rat myometrium are abolished under hypoxic conditions. Under these same conditions intracellular [Pi] rises and pH falls. The results of this study suggest that taken individually neither the effect of a rise in [Pi] nor a fall in pH on Ca(2+)-activated force generated by the contractile proteins can account for the effect of hypoxia on spontaneous contractions. PMID:8229854

  5. Synthesis, characterization and antibacterial activity of cellulose acetate-tin (IV) phosphate nanocomposite.

    PubMed

    Rathore, Bhim Singh; Sharma, Gaurav; Pathania, Deepak; Gupta, Vinod Kumar

    2014-03-15

    Cellulose acetate-tin (IV) phosphate nanocomposite (CA/TPNC) was prepared using simple method at 0-1 pH. The nanocomposite ion exchanger was characterized using some techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and thermogravimetric analysis (TGA/DTA/DSC). The nanocomposite material was explored for different properties such as ion exchange capacity, pH titration, elution behavior, thermal stability, and distribution coefficient. The ion exchange capacity of CA/TPNC was found higher compared to their inorganic counterpart. The distribution coefficient studies of nanocomposite ion exchanger were investigated for different metal ions. On the basis of distribution coefficient studies CA/TPNC material was found more selective for Cd(2+) and Mg(2+). CA/TPNC ion exchange was explored for antibacterial activities against E. coli bacteria.

  6. Evaluation of commonly used methods for the analysis of acid-soluble phosphate in internationally traded inorganic fertilizers.

    PubMed

    Hall, William L; Siegel, Sanford

    2014-01-01

    Several methodologies are used throughout the world to determine phosphate concentration (measured as PO4 and expressed as % P2O5) in fertilizers. Concentrated phosphate materials, including diammonium phosphate (DAP) and monoammonium phosphate (MAP), are traded in large volumes (millions of metric tons) internationally. The International Fertilizer Association (IFA) identified a need to assess the methods currently being used to measure the phosphate content for suitability (scope), accuracy, and repeatability. Even small discrepancies in the expressed P2O5 content can have a major financial impact on buyers and sellers as contracts are settled and import regulations are imposed. The IFA's Technical Committee selected a working group to address issues dealing with harmonization of fertilizer sampling and analytical methodologies. The working group identified phosphate content in DAP and MAP fertilizers as a major concern for commerce. The working group initiated a method screening and comparison project to assess method performance and to determine which methods, if any, could be considered best practice methods and, therefore, be deemed acceptable for use by the industry. In order to systematically review the acceptability of methods for consideration, the task force developed an assessment protocol outlined in a white paper involving three steps: (1) compile all known relevant methods practiced in global fertilizer trade, (2) review and evaluate methods based upon specific evaluation criteria, and (3) compare the methods that most closely fit the evaluation criteria by multilaboratory analysis of unknown materials for accuracy and repeatability. Six methods were evaluated for analysis of total phosphate in concentrated phosphate products. From these methods, four were determined to be acceptable as best practice methods. The study members proposed three of the methods, while a fourth method was commonly used among the participating laboratories. This publication

  7. Shp2 protein tyrosine phosphatase inhibitor activity of estramustine phosphate and its triterpenoid analogs

    PubMed Central

    Scott, Latanya M.; Chen, Liwei; Daniel, Kenyon G.; Brooks, Wesley H.; Guida, Wayne C.; Lawrence, Harshani R.; Sebti, Said M.; Lawrence, Nicholas J.; Wu, Jie

    2010-01-01

    Shp2 protein tyrosine phosphate (PTP) is a novel target for anticancer drug discovery. We identified estramustine phosphate as a Shp2 PTP inhibitor from the National Cancer Institute Approved Oncology Drug set. A focused structure-activity relationship study indicated that the 17- phosphate group is required for the Shp2 PTP inhibitor activity of estramustine phosphate. A search for estramustine phosphate analogs led to identification of two triperpenoids, enoxolone and celastrol, having Shp2 PTP inhibitor activity. With the previously reported PTP1B inhibitor trodusquemine, our study reveals steroids and triterpenoids with negatively charged phosphate, carboxylate, or sulfonate groups as novel pharmacophores of selective PTP inhibitors. PMID:21193311

  8. Inorganic lead and calcium interact positively in activation of calmodulin.

    PubMed

    Kern, M; Wisniewski, M; Cabell, L; Audesirk, G

    2000-06-01

    Calmodulin is a ubiquitous calcium-binding protein that mediates many of the intracellular actions of Ca2+ ions. The calcium-binding sites of calmodulin consist of four EF-hand motifs; full activation of calmodulin normally occurs when all four sites are occupied by Ca2+. Inorganic lead (PY2+) has been shown to activate calmodulin at total lead concentrations similar to the concentrations of Ca2+ required for activation (Goldstein and Ar, 1983; Habermann et al., 1983), but the free Pb2+ concentrations required for calmodulin activation have not been determined. In addition, it is possible that activation may occur with different sites occupied by different divalent cations, for example Ca2+ and Pb2+. We investigated the ability of free Pb2+, alone or in combination with Ca2+, to activate calmodulin. In aqueous media, N-phenyl-1-naphthylamine (NPN) and 8-anilino-1-naphthalenesulfonate (ANS) show increased fluorescence when bound to hydrophobic regions of proteins. This increased fluorescence has been used to monitor the conformational change that occurs during calmodulin activation (LaPorte et al., 1980). In the presence of calmodulin, both Ca2+ and Pb2+ stimulated increased fluorescence of NPN and ANS. Threshold and EC50 free metal concentrations were approximately 100 nM and 450-500 nM, respectively, for Ca2+ and 100 pM and 400-550 pM, respectively, for Pb2+. Fluorescence was enhanced by combinations of low concentrations of free Ca2+ and Pb2+; for example, as little as 20 pM free Pb2+ enhanced fluorescence in combination with 200 nM free Ca2+. The activity of the PDE1 isoform of cyclic nucleotide phosphodiesterase is stimulated by Ca2+/calmodulin (Wang et al., 1990). In the presence of calmodulin, we found that Ca2+ and Pb2+ activated calmodulin-stimulated PDE activity, with threshold and EC50 free metal concentrations of approximately 200 nM and 1200 nM, respectively, for Ca2+ and 300 pM and 430 pM, respectively, for Pb2+. PDE activity was stimulated by

  9. Preparation and photocatalytic activity of chemically-bonded phosphate ceramics containing TiO2

    NASA Astrophysics Data System (ADS)

    Martins, Monize Aparecida; de Lima, Bruna de Oliveira; Ferreira, Leticia Patrício; Colonetti, Emerson; Feltrin, Jucilene; De Noni, Agenor

    2017-05-01

    Titanium dioxide was incorporated into chemically-bonded phosphate ceramic for use as photocatalytic inorganic coating. The coatings obtained were applied to unglazed ceramic tiles and cured at 350 °C. The surfaces were characterized by photocatalytic activity, determined in aqueous medium, based on the degradation of methylene blue dye. The effects of the percentage of TiO2 and the thickness of the layer on the photocatalytic efficiency were evaluated. The influence of the incorporation of TiO2 on the consolidation of the phosphate matrix coating was investigated using the wear resistance test. The crystalline phases of the coatings obtained were determined by XRD. The microstructure of the surfaces was analyzed by SEM. The thermal curing treatment did not cause a phase transition from anatase to rutile. An increase in the photocatalytic activity of the coating was observed with an increase in the TiO2 content. The dye degradation indices ranged from 14.9 to 44.0%. The photocatalytic efficiency was not correlated with the thickness of the coating layer deposited. The resistance to wear decreased with an increase in the TiO2 content. Comparison with a commercial photocatalytic ceramic coating indicated that there is a range of values for the TiO2 contents which offer potential for photocatalytic applications.

  10. Novel phosphate-activated macrophages prevent ectopic calcification by increasing extracellular ATP and pyrophosphate

    PubMed Central

    Villa-Bellosta, Ricardo; Hamczyk, Magda R.; Andrés, Vicente

    2017-01-01

    Purpose Phosphorus is an essential nutrient involved in many pathobiological processes. Less than 1% of phosphorus is found in extracellular fluids as inorganic phosphate ion (Pi) in solution. High serum Pi level promotes ectopic calcification in many tissues, including blood vessels. Here, we studied the effect of elevated Pi concentration on macrophage polarization and calcification. Macrophages, present in virtually all tissues, play key roles in health and disease and display remarkable plasticity, being able to change their physiology in response to environmental cues. Methods and results High-throughput transcriptomic analysis and functional studies demonstrated that Pi induces unpolarized macrophages to adopt a phenotype closely resembling that of alternatively-activated M2 macrophages, as revealed by arginine hydrolysis and energetic and antioxidant profiles. Pi-induced macrophages showed an anti-calcifying action mediated by increased availability of extracellular ATP and pyrophosphate. Conclusion We conclude that the ability of Pi-activated macrophages to prevent calcium-phosphate deposition is a compensatory mechanism protecting tissues from hyperphosphatemia-induced pathologic calcification. PMID:28362852

  11. Faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart related to cytosolic inorganic phosphate (Pi) accumulation.

    PubMed

    Korzeniewski, Bernard

    2016-08-01

    A model of the cell bioenergetic system was used to compare the effect of oxidative phosphorylation (OXPHOS) deficiencies in a broad range of moderate ATP demand in skeletal muscle and heart. Computer simulations revealed that kinetic properties of the system are similar in both cases despite the much higher mitochondria content and "basic" OXPHOS activity in heart than in skeletal muscle, because of a much higher each-step activation (ESA) of OXPHOS in skeletal muscle than in heart. Large OXPHOS deficiencies lead in both tissues to a significant decrease in oxygen consumption (V̇o2) and phosphocreatine (PCr) and increase in cytosolic ADP, Pi, and H(+) The main difference between skeletal muscle and heart is a much higher cytosolic Pi concentration in healthy tissue and much higher cytosolic Pi accumulation (level) at low OXPHOS activities in the former, caused by a higher PCr level in healthy tissue (and higher total phosphate pool) and smaller Pi redistribution between cytosol and mitochondria at OXPHOS deficiency. This difference does not depend on ATP demand in a broad range. A much greater Pi increase and PCr decrease during rest-to-moderate work transition in skeletal muscle at OXPHOS deficiencies than at normal OXPHOS activity significantly slows down the V̇o2 on-kinetics. Because high cytosolic Pi concentrations cause fatigue in skeletal muscle and can compromise force generation in skeletal muscle and heart, this system property can contribute to the faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart. Shortly, skeletal muscle with large OXPHOS deficiencies becomes fatigued already during low/moderate exercise. Copyright © 2016 the American Physiological Society.

  12. Faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart related to cytosolic inorganic phosphate (Pi) accumulation

    PubMed Central

    2016-01-01

    A model of the cell bioenergetic system was used to compare the effect of oxidative phosphorylation (OXPHOS) deficiencies in a broad range of moderate ATP demand in skeletal muscle and heart. Computer simulations revealed that kinetic properties of the system are similar in both cases despite the much higher mitochondria content and “basic” OXPHOS activity in heart than in skeletal muscle, because of a much higher each-step activation (ESA) of OXPHOS in skeletal muscle than in heart. Large OXPHOS deficiencies lead in both tissues to a significant decrease in oxygen consumption (V̇o2) and phosphocreatine (PCr) and increase in cytosolic ADP, Pi, and H+. The main difference between skeletal muscle and heart is a much higher cytosolic Pi concentration in healthy tissue and much higher cytosolic Pi accumulation (level) at low OXPHOS activities in the former, caused by a higher PCr level in healthy tissue (and higher total phosphate pool) and smaller Pi redistribution between cytosol and mitochondria at OXPHOS deficiency. This difference does not depend on ATP demand in a broad range. A much greater Pi increase and PCr decrease during rest-to-moderate work transition in skeletal muscle at OXPHOS deficiencies than at normal OXPHOS activity significantly slows down the V̇o2 on-kinetics. Because high cytosolic Pi concentrations cause fatigue in skeletal muscle and can compromise force generation in skeletal muscle and heart, this system property can contribute to the faster and stronger manifestation of mitochondrial diseases in skeletal muscle than in heart. Shortly, skeletal muscle with large OXPHOS deficiencies becomes fatigued already during low/moderate exercise. PMID:27283913

  13. Effect of pH and coexisting anions on removal of phosphate from aqueous solutions by inorganic-based mesostructures.

    PubMed

    Choi, Jae-Woo; Choi, Yong-Soo; Hong, Seok-Won; Kim, Dong-Ju; Lee, Sang-Hyup

    2012-07-01

    This study investigated the effect of pH and the presence of coexisting (competitive) anions on the removal of phosphate by titanium mesostructures synthesized using do- or hexadecyltrimethylammonium bromide. To address these research objectives, experiments were conducted (1) under controlled initial pH values (2 to 10); and (2) through injection of nitrate, fluoride, chloride, or sulfate anions into a phosphate solution. Based on the experimental results, an initial of pH of 2 was found to be optimal for use of titanium mesostructures. The presence of fluoride anions in solution significantly decreased the removal efficiency of phosphate removal (3.56% at 3.95 mg/g). However, the addition of nitrate, chloride, and sulfate anions did not affect phosphate removal.

  14. Fluorometric method for inorganic pyrophosphatase activity detection and inhibitor screening based on click chemistry.

    PubMed

    Xu, Kefeng; Chen, Zhonghui; Zhou, Ling; Zheng, Ou; Wu, Xiaoping; Guo, Longhua; Qiu, Bin; Lin, Zhenyu; Chen, Guonan

    2015-01-06

    A fluorometric method for pyrophosphatase (PPase) activity detection was developed based on click chemistry. Cu(II) can coordinate with pyrophosphate (PPi), the addition of pyrophosphatase (PPase) into the above system can destroy the coordinate compound because PPase catalyzes the hydrolysis of PPi into inorganic phosphate and produces free Cu(II), and free Cu(II) can be reduced by sodium ascorbate (SA) to form Cu(I), which in turn initiates the ligating reaction between nonfluorescent 3-azidocoumarins and terminal alkynes to produce a highly fluorescent triazole complex, based on which, a simple and sensitive turn on fluorometric method for PPase can be developed. The fluorescence intensity of the system has a linear relationship with the logarithm of the PPase concentration in the range of 0.5 and 10 mU with a detection limit down to 0.2 mU (S/N = 3). This method is cost-effective and convenient without any labels or complicated operations. The proposed system was applied to screen the potential PPase inhibitor with high efficiency. The proposed method can be applied to diagnosis of PPase-related diseases.

  15. Heavy metal removal from aqueous solutions by activated phosphate rock.

    PubMed

    Elouear, Z; Bouzid, J; Boujelben, N; Feki, M; Jamoussi, F; Montiel, A

    2008-08-15

    The use of natural adsorbent such as phosphate rock to replace expensive imported synthetic adsorbent is particularly appropriate for developing countries such as Tunisia. In this study, the removal characteristics of lead, cadmium, copper and zinc ions from aqueous solution by activated phosphate rock were investigated under various operating variables like contact time, solution pH, initial metal concentration and temperature. The kinetic and the sorption process of these metal ions were compared for phosphate rock (PR) and activated phosphate rock (APR). To accomplish this objective we have: (a) characterized both (PR) and (APR) using different techniques (XRD, IR) and analyses (EDAX, BET-N(2)); and, (b) qualified and quantified the interaction of Pb(2+), Cd(2+), Cu(2+) and Zn(2+) with these sorbents through batch experiments. Initial uptake of these metal ions increases with time up to 1h for (PR) and 2h for (APR), after then, it reaches equilibrium. The maximum sorption obtained for (PR) and (APR) is between pH 2 and 3 for Pb(2+) and 4 and 6 for Cd(2+), Cu(2+) and Zn(2+). The effect of temperature has been carried out at 10, 20 and 40 degrees C. The data obtained from sorption isotherms of metal ions at different temperatures fit to linear form of Langmuir sorption equation. The heat of sorption (DeltaH degrees), free energy (DeltaG degrees) and change in entropy (DeltaS degrees) were calculated. They show that sorption of Pb(2+), Cd(2+), Cu(2+) and Zn(2+) on (PR) and (APR) an endothermic process. These findings are significant for future using of (APR) for the removal of heavy metal ions from wastewater under realistic competitive conditions in terms of initial heavy metals, concentrations and pH.

  16. Catalytically active monomers of E. coli glyceraldehyde-3-phosphate dehydrogenase.

    PubMed

    Levashov, P A; Muronetz, V I; Klyachko, N L; Nagradova, N K

    1998-04-01

    Monomeric forms of E. coli glyceraldehyde-3-phosphate dehydrogenase have been prepared using two different experimental approaches: (1) covalent immobilization of a tetramer on a solid support via a single subunit with subsequent dissociation of non-covalently bound subunits in the presence of urea, and (2) entrapment of monomeric species into reversed micelles of Aerosol OT in octane. Isolated monomers were shown to be catalytically active, exhibiting KM values close to the parameters characteristic of the tetrameric forms. Like tetramers, isolated monomers did not use NADP7 as a coenzyme.

  17. Inorganic phosphate-triggered release of anti-cancer arsenic trioxide from a self-delivery system: an in vitro and in vivo study

    NASA Astrophysics Data System (ADS)

    Chen, Fei-Yan; Yi, Jing-Wei; Gu, Zhe-Jia; Tang, Bin-Bing; Li, Jian-Qi; Li, Li; Kulkarni, Padmakar; Liu, Li; Mason, Ralph P.; Tang, Qun

    2016-03-01

    On-demand drug delivery is becoming feasible via the design of either exogenous or endogenous stimulus-responsive drug delivery systems. Herein we report the development of gadolinium arsenite nanoparticles as a self-delivery platform to store, deliver and release arsenic trioxide (ATO, Trisenox), a clinical anti-cancer drug. Specifically, unloading of the small molecule drug is triggered by an endogenous stimulus: inorganic phosphate (Pi) in the blood, fluid, and soft or hard tissue. Kinetics in vitro demonstrated that ATO is released with high ON/OFF specificity and no leakage was observed in the silent state. The nanoparticles induced tumor cell apoptosis, and reduced cancer cell migration and invasion. Plasma pharmacokinetics verified extended retention time, but no obvious disturbance of phosphate balance. Therapeutic efficacy on a liver cancer xenograft mouse model was dramatically potentiated with reduced toxicity compared to the free drug. These results suggest a new drug delivery strategy which might be applied for ATO therapy on solid tumors.On-demand drug delivery is becoming feasible via the design of either exogenous or endogenous stimulus-responsive drug delivery systems. Herein we report the development of gadolinium arsenite nanoparticles as a self-delivery platform to store, deliver and release arsenic trioxide (ATO, Trisenox), a clinical anti-cancer drug. Specifically, unloading of the small molecule drug is triggered by an endogenous stimulus: inorganic phosphate (Pi) in the blood, fluid, and soft or hard tissue. Kinetics in vitro demonstrated that ATO is released with high ON/OFF specificity and no leakage was observed in the silent state. The nanoparticles induced tumor cell apoptosis, and reduced cancer cell migration and invasion. Plasma pharmacokinetics verified extended retention time, but no obvious disturbance of phosphate balance. Therapeutic efficacy on a liver cancer xenograft mouse model was dramatically potentiated with reduced

  18. ATP binding and hydrolysis steps of the uni-site catalysis by the mitochondrial F(1)-ATPase are affected by inorganic phosphate.

    PubMed

    Milgrom, Yakov M

    2010-10-01

    The effect of inorganic phosphate (P(i)) on uni-site ATP binding and hydrolysis by the nucleotide-depleted F(1)-ATPase from beef heart mitochondria (ndMF(1)) has been investigated. It is shown for the first time that P(i) decreases the apparent rate constant of uni-site ATP binding by ndMF(1) 3-fold with the K(d) of 0.38+/-0.14mM. During uni-site ATP hydrolysis, P(i) also shifts equilibrium between bound ATP and ADP+P(i) in the direction of ATP synthesis with the K(d) of 0.17+/-0.03mM. However, 10mM P(i) does not significantly affect ATP binding during multi-site catalysis.

  19. Effects of acute sodium fluoride exposure on kidney function, water homeostasis, and renal handling of calcium and inorganic phosphate.

    PubMed

    Santoyo-Sanchez, Mitzi Paola; del Carmen Silva-Lucero, Maria; Arreola-Mendoza, Laura; Barbier, Olivier Christophe

    2013-06-01

    Fluoride compounds are abundant and widely distributed in the environment at a variety of concentrations. Further, fluoride induces toxic effects in target organs such as the liver and kidney. In this study, we performed an early analysis of renal function using a clearance technique in Wistar rats acutely exposed to fluoride at a plasma concentration of 0.625 μg/ml. Our results revealed that fluoride, at a concentration close to the concentration present in the serum after environmental exposure, induced a significant tubular dysfunction, resulting in diluted urine, impaired protein reabsorption, and increased calcium and phosphate urinary excretion. Our work demonstrates that even acute exposures to low concentrations of NaF may induce renal damage and confirms that, after exposure, the kidney participates directly in the calcium and phosphate deficiencies observed in fluoride-exposed populations.

  20. Poly(alkylene phosphates): from synthetic models of biomacromolecules and biomembranes toward polymer-inorganic hybrids (mimicking biomineralization).

    PubMed

    Penczek, Stanislaw; Pretula, Julia; Kaluzynski, Krzysztof

    2005-01-01

    Syntheses of poly(alkylene phosphates), with repeating units having two or three methylene groups and phosphoryl groups and mimicking backbones of biomacromolecules, are reviewed. Two major methods elaborated in this laboratory, namely, ring-opening polymerization and transesterification, are described. The resulting polymers were used as carriers of cations (Ca2+ and Mg2+) in membrane processes and in controlling the crystallization of CaCO3, in a process related to biomineralization.

  1. Inhibitory activity of phosphates on molds isolated from foods and food processing plants.

    PubMed

    Suárez, V B; Frisón, L; de Basílico, M Z; Rivera, M; Reinheimer, J A

    2005-11-01

    Six commercial phosphates were evaluated for inhibition of the growth of 17 molds isolated from food sources. The assays were performed at neutral and natural (without pH adjustment) pH values, and the molds were streaked on plate count agar with added phosphates. Phosphate concentrations of 0.1, 0.3, 0.5, 1.0, and 1.5% (wt/vol) were used, and the MIC was determined. The resistance of molds to phosphates depended on the species. At a neutral pH, Aspergillus ochraceus and Fusarium proliferatum were resistant to all phosphates at all concentrations assayed, and Byssochlamys nivea, Aureobasidium pullulans, and Penicillium glabrum were most sensitive. The most inhibitory phosphates were those with chain lengths greater than 15 phosphate units and the highest sequestering power. At natural pH values (resulting from dissolving the phosphate in the medium), inhibitory activity changed dramatically for phosphates that produced alkaline or acidic pH in the medium. Phosphates with alkaline pH values (sodium tripolyphosphate of high solubility, sodium tripolyphosphate, and sodium neutral pyrophosphate) were much more inhibitory than phosphates at a neutral pH, but sodium acid pyrophosphate (acidic pH) had decreased inhibitory activity. The results indicate that some phosphates could be used in the food industry to inhibit molds linked to food spoilage.

  2. Effect of aluminum phosphate on alkaline phosphatase activity of polyurethane foam immobilized cyanobacteria.

    PubMed

    Ramalingam, N; Prasanna, B Gowtham

    2006-09-01

    The impact of insoluble phosphorus such as aluminum and rock phosphate on alkaline phosphatase activity of polyurethane foam immobilized cyanobacteria was assessed. Polyurethane foam immobilized Nodularia recorded the highest alkaline phosphatase activity of 9.04 (m. mol p-nitrophenol released h(-1) mg(-1) protein) in vitro. A higher concentration of aluminum phosphate was recorded a 25% reduction in alkaline phosphatase activity, ammonia content, and available phosphorus in culture filtrate of polyurethane foam immobilized cyanobacteria. In general, immobilized cyanobacteria exhibited a higher alkaline phosphatase activity in rock phosphate than aluminum phosphate.

  3. Transformation of inorganic P fractions of soil and plant growth promotion by phosphate-solubilizing ability of Penicillium oxalicum I1.

    PubMed

    Gong, Mingbo; Du, Peng; Liu, Xue; Zhu, Changxiong

    2014-12-01

    The solubilization of tricalcium phosphate is often considered as the standard for screening of most phosphate-solubilizing microorganisms (PSMs). However, usually the effect of large-scale application of PSM on the promotion of crop growth varies. This study presents an efficient method for screening and testing phosphate-solubilizing fungus that enhance plant growth. A fungus Penicillium oxalicum I1 (P-I1) was isolated and identified that had high ability of phosphate-solubilization and could utilize maize root exudates as sources, and propagate well in vitro and in soil. P-I1 excreted oxalic acid and reached 593.9 μg/ml, and the pH value was decreased from 6.90 to 1.65 in 26 h. The amount of P-I1 increased by 48-fold in 28 d and was maintained for 49 d in soil. PSM showed selectivity on the transformation of the different forms of phosphorus, a wide range of insoluble phosphates, such as Ca₈H₂(PO₄)₆·5H₂O, AlPO₄, FePO₄, and Ca10(PO₄)₆(OH)₂, were converted to soluble CaHPO₄in soil, and CaHPO₄was also inhibited from being converted into insoluble phosphate by P-I1. The Ca₂-P content reached 27.11 μg/g soil on day 28 at 20°C, which increased by 110.32%, and plant growth promotion was tested and verified, the results showed that maize yield increased remarkably than control after inoculated P-I1, maize yield increased maximum by 14.47%. The data presented that P-I1 appear attractive for exploring their plant growth-promoting activity and potential field application.

  4. Special Feature: Oxygen isotope ratios of PO4: An inorganic indicator of enzymatic activity and P metabolism and a new biomarker in the search for life

    NASA Astrophysics Data System (ADS)

    Blake, Ruth E.; Alt, Jeffrey C.; Martini, Anna M.

    2001-02-01

    The distinctive relations between biological activity and isotopic effect recorded in biomarkers (e.g., carbon and sulfur isotope ratios) have allowed scientists to suggest that life originated on this planet nearly 3.8 billion years ago. The existence of life on other planets may be similarly identified by geochemical biomarkers, including the oxygen isotope ratio of phosphate (18Op) presented here. At low near-surface temperatures, the exchange of oxygen isotopes between phosphate and water requires enzymatic catalysis. Because enzymes are indicative of cellular activity,the demonstration of enzyme-catalyzed PO4-H2O exchange is indicative of the presence of life. Results of laboratory experiments are presented that clearly show that δ18OP values of inorganic phosphate can be used to detect enzymatic activity and microbial metabolism of phosphate. Applications of δ18Op as a biomarker are presented for two Earth environments relevant to the search for extraterrestrial life: a shallow groundwater reservoir and a marine hydrothermal vent system. With the development of in situ analytical techniques and future planned sample return strategies, δ18Op may provide an important biosignature of the presence of life in extraterrestrial systems such as that on Mars.

  5. Oxygen isotope ratios of PO4: An inorganic indicator of enzymatic activity and P metabolism and a new biomarker in the search for life

    PubMed Central

    Blake, Ruth E.; Alt, Jeffrey C.; Martini, Anna M.

    2001-01-01

    The distinctive relations between biological activity and isotopic effect recorded in biomarkers (e.g., carbon and sulfur isotope ratios) have allowed scientists to suggest that life originated on this planet nearly 3.8 billion years ago. The existence of life on other planets may be similarly identified by geochemical biomarkers, including the oxygen isotope ratio of phosphate (δ18Op) presented here. At low near-surface temperatures, the exchange of oxygen isotopes between phosphate and water requires enzymatic catalysis. Because enzymes are indicative of cellular activity, the demonstration of enzyme-catalyzed PO4–H2O exchange is indicative of the presence of life. Results of laboratory experiments are presented that clearly show that δ18OP values of inorganic phosphate can be used to detect enzymatic activity and microbial metabolism of phosphate. Applications of δ18Op as a biomarker are presented for two Earth environments relevant to the search for extraterrestrial life: a shallow groundwater reservoir and a marine hydrothermal vent system. With the development of in situ analytical techniques and future planned sample return strategies, δ18Op may provide an important biosignature of the presence of life in extraterrestrial systems such as that on Mars. PMID:11226207

  6. Oxygen isotope ratios of PO4: an inorganic indicator of enzymatic activity and P metabolism and a new biomarker in the search for life.

    PubMed

    Blake, R E; Alt, J C; Martini, A M

    2001-02-27

    The distinctive relations between biological activity and isotopic effect recorded in biomarkers (e.g., carbon and sulfur isotope ratios) have allowed scientists to suggest that life originated on this planet nearly 3.8 billion years ago. The existence of life on other planets may be similarly identified by geochemical biomarkers, including the oxygen isotope ratio of phosphate (delta(18)O(p)) presented here. At low near-surface temperatures, the exchange of oxygen isotopes between phosphate and water requires enzymatic catalysis. Because enzymes are indicative of cellular activity, the demonstration of enzyme-catalyzed PO(4)-H(2)O exchange is indicative of the presence of life. Results of laboratory experiments are presented that clearly show that delta(18)O(P) values of inorganic phosphate can be used to detect enzymatic activity and microbial metabolism of phosphate. Applications of delta(18)O(p) as a biomarker are presented for two Earth environments relevant to the search for extraterrestrial life: a shallow groundwater reservoir and a marine hydrothermal vent system. With the development of in situ analytical techniques and future planned sample return strategies, delta(18)O(p) may provide an important biosignature of the presence of life in extraterrestrial systems such as that on Mars.

  7. Activation and fluoride-assisted phosphating of aluminum-silicon-coated steel.

    PubMed

    Schneider, Paul; Sigel, Reinhard; Lange, Miriam M; Beier, Frank; Renner, Frank U; Erbe, Andreas

    2013-05-22

    Phosphating is a crucial process in the corrosion protection of metals. Here, activation and fluoride-assisted tricationic phosphating is investigated on aluminum-silicon (AS) coated steel surfaces. Dynamic light scattering results from the activation bath show a bimodal size distribution, with hydrodynamic radii of ~400 nm and ~10 μm. For the smaller particle fraction, static light scattering results are consistent with the interpretation of disklike particles as scattering objects. Particles of the larger fraction sediment with time. In the presence of electrolyte, the scattering intensity from the larger particle fraction increases. Coagulation with time is suggested to be related to the decrease in activity of the activation bath. Scanning Auger microscopy (SAM) shows a higher phosphorus concentration after titanium phosphate activation in the Al-rich areas compared to the Si-rich areas of the AS coatings. There is no correlation between the size of the species in the activation bath, and the size of the phosphate-containing regions on the activated surface. Phosphating was performed in the presence of hexafluorosilicic acid, H2SiF6, ammonium hydrogen difluoride, NH4HF2, and both, at an initial pH of 2.5. The absence of crystals after phosphating with H2SiF6 is an indication that SiF6(2-) is the final product of the oxide dissolution in the presence of fluoride. In the presence of NH4HF2, the Si-rich regions of the surface are phosphated before the Si-poor (Al-rich) regions. Hence, the phosphate distribution after activation and after phosphating are opposite. These results show that a high surface concentration of phosphate after activation is not sufficient for a high coverage with phosphate crystals after phosphating.

  8. Sevelamer hydrochloride binds phosphate released from phytate in chicks fed 1α-hydroxy cholecalciferol.

    PubMed

    Bobeck, Elizabeth A; Meyer, Katie M; Helvig, Christian; Petkovich, Martin; Cook, Mark E

    2013-01-01

    Hyperphosphatemia in animal models of human renal disease has been linked to increased risk of death. Phosphate binders (e.g., sevelamer hydrochloride) and plant-based, low phosphate diets are used to reduce dietary phosphate load; however, animal models show that treatment with active forms of vitamin D(3) (e.g., calcitriol, a renal disease therapy) renders plant phytate phosphate available for absorption. Using an established chick model, the effectiveness of sevelamer in preventing the apparent absorption of liberated phytate phosphate during active vitamin D use was investigated in two separate experiments. One-day-old chicks were fed ad libitum a basal diet containing deficient levels of inorganic phosphate (0.13%), but adequate in total phosphate (0.40%, 0.23% as phytate phosphate), with or without the inclusion of sevelamer hydrochloride (a phosphate binder), available inorganic phosphate, or active vitamin D as 1α-(OH) D(3). Plasma phosphate (mg/dL), total bone ash (%), and weight gain (g). Adding inorganic phosphate (0.36%) or 1α-(OH) D(3) increased plasma phosphate 49% and 48%, respectively (P < .0001), and bone ash 23% and 19%, respectively (P < .001). The addition of 1% sevelamer to the basal diet with added inorganic phosphate or 1α-(OH) D(3) significantly decreased plasma phosphate by 28% and 20%, respectively (P < .01). Active vitamin D increased the availability of phytate phosphate for intestinal absorption in an animal model; however, sevelamer effectively reduced the availability of phosphate liberated from phytate. These data imply that sevelamer has phytate phosphate binding efficacy. Copyright © 2013 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  9. Biologic activity of cyclic and caged phosphates: a review.

    PubMed

    Lorke, Dietrich E; Stegmeier-Petroianu, Anka; Petroianu, Georg A

    2017-01-01

    The recognition in the early 1960s by Morifusa Eto that tri-o-cresyl phosphate (TOCP) is hydroxylated by the cytochrome P450 system to an intermediate that spontaneously cyclizes to a neurotoxic phosphate (saligenin phosphate ester) ignited the interest in this group of compounds. Only the ortho isomer can cyclize and clinically cause Organo Phosphate Induced Delayed Neurotoxicity (OPIDN); the meta and para isomers of tri-cresyl phosphate are not neuropathic because they are unable to form stable cyclic saligenin phosphate esters. This review identifies the diverse biological effects associated with various cyclic and caged phosphates and phosphonates and their possible use. Cyclic compounds that inhibit acetylcholine esterase (AChE), such as salithion, can be employed as pesticides. Others are neurotoxic, most probably because of inhibition of neuropathy target esterase (NTE). Cyclic phosphates that inhibit lipases, the cyclipostins, possibly represent promising therapeutic avenues for the treatment of type 2 diabetes mellitus and/or microbial infections; those compounds inhibiting β-lactamase may prevent bacterial resistance against β-lactam antibiotics. Naturally occurring cyclic phosphates, such as cyclic AMP, cyclic phosphatidic acid and the ryanodine receptor modulator cyclic adenosine diphosphate ribose, play an important physiological role in signal transduction. Moreover, some cyclic phosphates are GABA-antagonists, while others are an essential component of Molybdenum-containing enzymes. Some cyclic phosphates (cyclophosphamide, ifosfamide) are clinically used in tumor therapy, while the coupling of therapeutic agents with other cyclic phosphates (HepDirect® Technology) allows drugs to be targeted to specific organs. Possible clinical applications of these compounds are considered. Copyright © 2016 John Wiley & Sons, Ltd.

  10. The SPX domain of the yeast low-affinity phosphate transporter Pho90 regulates transport activity

    PubMed Central

    Hürlimann, Hans Caspar; Pinson, Benoît; Stadler-Waibel, Martha; Zeeman, Samuel C; Freimoser, Florian M

    2009-01-01

    Yeast has two phosphate-uptake systems that complement each other: the high-affinity transporters (Pho84 and Pho89) are active under phosphate starvation, whereas Pho87 and Pho90 are low-affinity transporters that function when phosphate is abundant. Here, we report new regulatory functions of the amino-terminal SPX domain of Pho87 and Pho90. By studying truncated versions of Pho87 and Pho90, we show that the SPX domain limits the phosphate-uptake velocity, suppresses phosphate efflux and affects the regulation of the phosphate signal transduction pathway. Furthermore, split-ubiquitin assays and co-immunoprecipitation suggest that the SPX domain of both Pho90 and Pho87 interacts physically with the regulatory protein Spl2. This work suggests that the SPX domain inhibits low-affinity phosphate transport through a physical interaction with Spl2. PMID:19590579

  11. Modeling the Thermodynamics of Mixed Organic-Inorganic Aerosols to Predict Water Activities and Phase Equilibria

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Luo, B.; Peter, T.

    2008-12-01

    Tropospheric aerosol particles contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behavior. While the thermodynamics of aqueous inorganic systems at atmospheric temperatures are well established, little is known about the physicochemistry of mixed organic-inorganic particles. Salting-out and salting-in effects result from organic-inorganic interactions and are used to improve industrial separation processes. In the atmosphere, they may influence the aerosol phases. Liquid-liquid phase separations into a mainly polar (aqueous) and a less polar organic phase may considerably influence the gas/particle partitioning of semi-volatile substances compared to a single phase estimation. Moreover, the phases present in the aerosol define the reaction medium for heterogeneous and multiphase chemistry occurring in aerosol particles. A correct description of these phases is needed when gas- or cloud-phase reaction schemes are adapted to aerosols. Non-ideal thermodynamic behavior in mixtures is usually described by an expression for the excess Gibbs energy. We present the group-contribution model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients), which explicitly accounts for molecular interactions between solution constituents, both organic and inorganic, to calculate activities, chemical potentials and the total Gibbs energy of mixed systems. This model allows to compute vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid (SLE) equilibria within one framework. Focusing on atmospheric applications we considered eight different cations, five anions and a wide range of alcohols/polyols as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are very well represented up to high ionic strength. We show that the semiempirical middle

  12. Succinyl-CoA synthetase is a phosphate target for the activation of mitochondrial metabolism.

    PubMed

    Phillips, Darci; Aponte, Angel M; French, Stephanie A; Chess, David J; Balaban, Robert S

    2009-08-04

    Succinyl-CoA synthetase (SCS) is the only mitochondrial enzyme capable of ATP production via substrate level phosphorylation in the absence of oxygen, but it also plays a key role in the citric acid cycle, ketone metabolism, and heme synthesis. Inorganic phosphate (P(i)) is a signaling molecule capable of activating oxidative phosphorylation at several sites, including NADH generation and as a substrate for ATP formation. In this study, it was shown that P(i) binds the porcine heart SCS alpha-subunit (SCSalpha) in a noncovalent manner and enhances its enzymatic activity, thereby providing a new target for P(i) activation in mitochondria. Coupling 32P labeling of intact mitochondria with SDS gel electrophoresis revealed that 32P labeling of SCSalpha was enhanced in substrate-depleted mitochondria. Using mitochondrial extracts and purified bacterial SCS (BSCS), we showed that this enhanced 32P labeling resulted from a simple binding of 32P, not covalent protein phosphorylation. The ability of SCSalpha to retain its 32P throughout the SDS denaturing gel process was unique over the entire mitochondrial proteome. In vitro studies also revealed a P(i)-induced activation of SCS activity by more than 2-fold when mitochondrial extracts and purified BSCS were incubated with millimolar concentrations of P(i). Since the level of 32P binding to SCSalpha was increased in substrate-depleted mitochondria, where the matrix P(i) concentration is increased, we conclude that SCS activation by P(i) binding represents another mitochondrial target for the P(i)-induced activation of oxidative phosphorylation and anaerobic ATP production in energy-limited mitochondria.

  13. Inorganic Polyphosphates Regulate Hexokinase Activity and Reactive Oxygen Species Generation in Mitochondria of Rhipicephalus (Boophilus) microplus Embryo

    PubMed Central

    Fraga, Amanda; Moraes, Jorge; da Silva, José Roberto; Costa, Evenilton P.; Menezes, Jackson; da Silva Vaz Jr, Itabajara; Logullo, Carlos; da Fonseca, Rodrigo Nunes; Campos, Eldo

    2013-01-01

    The physiological roles of polyphosphates (poly P) recently found in arthropod mitochondria remain obscure. Here, the possible involvement of poly P with reactive oxygen species generation in mitochondria of Rhipicephalus microplus embryos was investigated. Mitochondrial hexokinase and scavenger antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione reductase were assayed during embryogenesis of R. microplus. The influence of poly P3 and poly P15 were analyzed during the period of higher enzymatic activity during embryogenesis. Both poly Ps inhibited hexokinase activity by up to 90% and, interestingly, the mitochondrial membrane exopolyphosphatase activity was stimulated by the hexokinase reaction product, glucose-6-phosphate. Poly P increased hydrogen peroxide generation in mitochondria in a situation where mitochondrial hexokinase is also active. The superoxide dismutase, catalase and glutathione reductase activities were higher during embryo cellularization, at the end of embryogenesis and during embryo segmentation, respectively. All of the enzymes were stimulated by poly P3. However, superoxide dismutase was not affected by poly P15, catalase activity was stimulated only at high concentrations and glutathione reductase was the only enzyme that was stimulated in the same way by both poly Ps. Altogether, our results indicate that inorganic polyphosphate and mitochondrial membrane exopolyphosphatase regulation can be correlated with the generation of reactive oxygen species in the mitochondria of R. microplus embryos. PMID:23983617

  14. Interaction between phosphate and acid-activated neutralized red mud during adsorption process

    NASA Astrophysics Data System (ADS)

    Ye, Jie; Cong, Xiangna; Zhang, Panyue; Hoffmann, Erhard; Zeng, Guangming; Liu, Yang; Fang, Wei; Wu, Yan; Zhang, Haibo

    2015-11-01

    Acid-activated neutralized red mud (AaN-RM) has become a promising adsorbent for phosphate adsorption. The maximum phosphate adsorption capacity of AaN-RM reached 492.46 mg g-1 in this study, which was much higher than that of many other adsorbents. However, no study has specifically investigated how the phosphate reacted with AaN-RM. For the first time the interaction between phosphate and AaN-RM during adsorption process was investigated in this research. Kinetic models and isotherms were used to analyze the possible reaction pathways between AaN-RM and phosphate. Particularly, the phosphate complexes on AaN-RM surface, and the exact role of different adsorption mechanisms were systemically identified. The phosphate adsorption was well described by pseudo second-order kinetic model and Langmuir-Freundlich isotherm, which suggested that chemisorption occurred between the phosphate and AaN-RM, and the phosphate adsorption was governed by heterogeneous processes. Furthermore, the phosphate complexes of Fe-P, Al-P, Fe-P-H3PO4 and Al-P-H3PO4 were formed on AaN-RM surface through ion exchange, precipitation and surface deposition mechanisms. XPS analysis of P 2p peak showed that 59.78% of the phosphate was adsorbed through the ion exchange and precipitation with strong chemical bonds, and 40.22% was adsorbed through the surface deposition with weak chemical bonds.

  15. High levels of the type III inorganic phosphate transporter PiT1 (SLC20A1) can confer faster cell adhesion

    SciTech Connect

    Kongsfelt, Iben Boutrup; Byskov, Kristina; Pedersen, Lasse Ebdrup; Pedersen, Lene

    2014-08-01

    The inorganic phosphate transporter PiT1 (SLC20A1) is ubiquitously expressed in mammalian cells. We recently showed that overexpression of human PiT1 was sufficient to increase proliferation of two strict density-inhibited cell lines, murine fibroblastic NIH3T3 and pre-osteoblastic MC3T3-E1 cells, and allowed the cultures to grow to higher cell densities. In addition, upon transformation NIH3T3 cells showed increased ability to form colonies in soft agar. The cellular regulation of PiT1 expression supports that cells utilize the PiT1 levels to control proliferation, with non-proliferating cells showing the lowest PiT1 mRNA levels. The mechanism behind the role of PiT1 in increased cell proliferation is not known. We, however, found that compared to control cells, cultures of NIH3T3 cells overexpressing PiT1 upon seeding showed increased cell number after 24 h and had shifted more cells from G0/G1 to S+G2/M within 12 h, suggesting that an early event may play a role. We here show that expression of human PiT1 in NIH3T3 cells led to faster cell adhesion; this effect was not cell type specific in that it was also observed when expressing human PiT1 in MC3T3-E1 cells. We also show for NIH3T3 that PiT1 overexpression led to faster cell spreading. The final total numbers of attached cells did, however, not differ between cultures of PiT1 overexpressing cells and control cells of neither cell type. We suggest that the PiT1-mediated fast adhesion potentials allow the cells to go faster out of G0/G1 and thereby contribute to their proliferative advantage within the first 24 h after seeding. - Highlights: • Effects of elevated levels of the inorganic phosphate transporter PiT1 were studied. • The density-inhibited murine cell lines NIH3T3 and MC3T3-E1 showed faster adhesion. • NIH3T3 cells showed faster spreading. • We suggest that the faster adhesion/spreading contributes to faster proliferation.

  16. Functional expression of PHO1 to the Golgi and trans-Golgi network and its role in export of inorganic phosphate.

    PubMed

    Arpat, A Bulak; Magliano, Pasqualina; Wege, Stefanie; Rouached, Hatem; Stefanovic, Aleksandra; Poirier, Yves

    2012-08-01

    Arabidopsis thaliana PHO1 is primarily expressed in the root vascular cylinder and is involved in the transfer of inorganic phosphate (Pi) from roots to shoots. To analyze the role of PHO1 in transport of Pi, we have generated transgenic plants expressing PHO1 in ectopic A. thaliana tissues using an estradiol-inducible promoter. Leaves treated with estradiol showed strong PHO1 expression, leading to detectable accumulation of PHO1 protein. Estradiol-mediated induction of PHO1 in leaves from soil-grown plants, in leaves and roots of plants grown in liquid culture, or in leaf mesophyll protoplasts, was all accompanied by the specific release of Pi to the extracellular medium as early as 2-3 h after addition of estradiol. Net Pi export triggered by PHO1 induction was enhanced by high extracellular Pi and weakly inhibited by the proton-ionophore carbonyl cyanide m-chlorophenylhydrazone. Expression of a PHO1-GFP construct complementing the pho1 mutant revealed GFP expression in punctate structures in the pericycle cells but no fluorescence at the plasma membrane. When expressed in onion epidermal cells or in tobacco mesophyll cells, PHO1-GFP was associated with similar punctate structures that co-localized with the Golgi/trans-Golgi network and uncharacterized vesicles. However, PHO1-GFP could be partially relocated to the plasma membrane in leaves infiltrated with a high-phosphate solution. Together, these results show that PHO1 can trigger Pi export in ectopic plant cells, strongly indicating that PHO1 is itself a Pi exporter. Interestingly, PHO1-mediated Pi export was associated with its localization to the Golgi and trans-Golgi networks, revealing a role for these organelles in Pi transport.

  17. Synthesis and structural characterization of a new chiral porous hybrid organic–inorganic material based on γ-zirconium phosphates and L-(+)-phosphoserine

    SciTech Connect

    Alhendawi, Hussein M.H.

    2013-05-01

    In the present work, a chiral layered derivative of γ-zirconium phosphate (γ-ZrP) containing L-(+)-phosphoserine (γ-ZrP-PS*) covalently attached to inorganic layers has been prepared by means of topotactic exchange reaction. This organic–inorganic derivative is characterized by X-ray diffractometry, Solid {sup 13}C–NMR and FT-IR spectrophotometries and thermal analyses. A maximum level of topotactic replacement of 20% is achieved. Under both the acidic environment of the interlayer region of γ-ZrP and the acidic synthesis conditions, the hydrolysis of the ester bond of PS* is expected to take place to some extent. For this reason, it was impossible to exceed the recent percentage, which in turn reflects the relative moderate stability of the above mentioned bond under these conditions. In order to be more certain with regard to an expected further hydrolysis for this bond after separation, a sample of γ-ZrP-PS* was stored in a desiccator over a saturated solution of BaCl{sub 2} (90% relative humidity) for three months, and then the sample re-analyzed once again. Surprisingly, the results show that the sample still keeps almost the same level of exchange (i.e., 20%). Second, it is revealed that the sample almost gives the same spectroscopic and thermal behavior. This could be attributed to the less acidic character of the partially exchanged inorganic layers of the sample in comparison with that of the precursor γ-ZrP. Therefore, the PS* molecules persist and stay there into the interlayer gallery without further hydrolysis. - Graphical abstract: • Red: oxygen • White: zirconium • Cyan: carbon • Yellow: phosphorus • Blue: nitrogen. Highlights: • L-(+)-Phosphoserine (PS*) is exchanged with γ-ZrP by means of topotactic exchange. • The maximum exchange level is 20%. • γ-ZrP is functionalized with chiral amino acid group. • γ-ZrP-PS* has large chiral space for huge guest molecules to be intercalated.

  18. Inorganic nutrient availability affects organic matter fluxes and metabolic activity in the soft coral genus Xenia.

    PubMed

    Bednarz, Vanessa N; Naumann, Malik S; Niggl, Wolfgang; Wild, Christian

    2012-10-15

    The release of organic matter (OM) by scleractinian corals represents a key physiological process that importantly contributes to coral reef ecosystem functioning, and is affected by inorganic nutrient availability. Although OM fluxes have been studied for several dominant reef taxa, no information is available for soft corals, one of the major benthic groups in tropical reef environments. Thus, this study investigates OM fluxes along with other key physiological parameters (i.e. photosynthesis, respiration and chlorophyll a tissue content) in the common soft coral genus Xenia after a 4-week exposure period to elevated ammonium (N; 20.0 μmol l(-1)), phosphate (P; 2.0 μmol l(-1)) and combined inorganic nutrient enrichment treatment (N+P). Corals maintained without nutrient enrichment served as non-treated controls and revealed constant uptake rates for particulate organic carbon (POC) (-0.315±0.161 mg POC m(-2) coral surface area h(-1)), particulate nitrogen (PN) (-0.053±0.018 mg PN m(-2) h(-1)) and dissolved organic carbon (DOC) (-4.8±2.1 mg DOC m(-2) h(-1)). Although DOC uptake significantly increased in the N treatment, POC flux was not affected. The P treatment significantly enhanced PN release as well as photosynthesis and respiration rates, suggesting that autotrophic carbon acquisition of zooxanthellae endosymbionts influences OM fluxes by the coral host. Our physiological findings confirm the significant effect of inorganic nutrient availability on OM fluxes and key metabolic processes for the soft coral Xenia, and provide the first clues on OM cycles initiated by soft corals in reef environments exposed to ambient and elevated inorganic nutrient concentrations.

  19. Novel, inorganic composites using porous, alkali-activated, aluminosilicate binders

    NASA Astrophysics Data System (ADS)

    Musil, Sean

    Geopolymers are an inorganic polymeric material composed of alumina, silica, and alkali metal oxides. Geopolymers are chemical and fire resistant, can be used as refractory adhesives, and are processed at or near ambient temperature. These properties make geopolymer an attractive choice as a matrix material for elevated temperature composites. This body of research investigated numerous different reinforcement possibilities and variants of geopolymer matrix material and characterized their mechanical performance in tension, flexure and flexural creep. Reinforcements can then be chosen based on the resulting properties to tailor the geopolymer matrix composites to a specific application condition. Geopolymer matrix composites combine the ease of processing of polymer matrix composites with the high temperature capability of ceramic matrix composites. This study incorporated particulate, unidirectional fiber and woven fiber reinforcements. Sodium, potassium, and cesium based geopolymer matrices were evaluated with cesium based geopolymer showing great promise as a high temperature matrix material. It showed the best strength retention at elevated temperature, as well as a very low coefficient of thermal expansion when crystallized into pollucite. These qualities made cesium geopolymer the best choice for creep resistant applications. Cesium geopolymer binders were combined with unidirectional continuous polycrystalline mullite fibers (Nextel(TM) 720) and single crystal mullite fibers, then the matrix was crystallized to form cubic pollucite. Single crystal mullite fibers were obtained by the internal crystallization method and show excellent creep resistance up to 1400°C. High temperature flexural strength and flexural creep resistance of pollucite and polycrystalline/single-crystal fibers was evaluated at 1000-1400°C.

  20. Synthesis of a novel organic-inorganic hybrid of polyaniline/titanium phosphate for Re(VII) removal.

    PubMed

    Gao, Yang; Chen, Changlun; Chen, He; Zhang, Rui; Wang, Xiangke

    2015-05-21

    The organic-inorganic hybrid material of polyaniline/titanium(IV) (PANI/Ti(HPO4)2) was synthesized by an oxidative polymerization reaction. The PANI/Ti(HPO4)2 was applied to remove Re(VII). The size of Ti(HPO4)2 nanoplates has no obvious effect on the sorption capacity. The effects of various environmental factors (such as pH, extra anions (NO3(-) and MO4(2-)) and temperature) on Re(VII) sorption to PANI/Ti(HPO4)2 were investigated by batch experiments. The sorption kinetics followed a pseudo-second-order model. The nitrogen-containing functional groups of PANI promoted Re(VII) sorption. The PANI/Ti(HPO4)2 exhibited excellent maximum sorption capacity to Re(VII) (47.62 mg g(-1)), which was superior to that of PANI (10.75 mg g(-1)) and much higher than that of many other sorbents. The sorption isotherms of Re(VII) can be well fitted with the Langmuir model. Re(VII) sorption decreased with increasing solution pH at pH > 4.0, which implied that Re(VII) sorption on PANI/Ti(HPO4)2 might be attributed to the outer-sphere complexation between amine and imine groups on the surface of PANI/Ti(HPO4)2 and Re(VII). This study implies that the hybrid material of PANI/Ti(HPO4)2 can be regarded as a potential sorbent to remove Re(VII) and its analogues from large volumes of aqueous solutions.

  1. Boosting Proton Conductivity in Highly Robust 3D Inorganic Cationic Extended Frameworks through Ion Exchange with Dihydrogen Phosphate Anions.

    PubMed

    Xiao, Chengliang; Wang, Yaxing; Chen, Lanhua; Yin, Xuemiao; Shu, Jie; Sheng, Daopeng; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Wang, Shuao

    2015-12-01

    The limited long-term hydrolytic stability of rapidly emerging 3D-extended framework materials (MOFs, COFs, MOPs, etc.) is still one of major barriers for their practical applications as new solid-state electrolytes in fuel cells. To obtain hydrolytically stable materials, two H2 PO4 (-) -exchanged 3D inorganic cationic extended frameworks (CEFs) were successfully prepared by a facile anion-exchange method. Both anion-exchanged CEFs (YbO(OH)P and NDTBP) show significantly enhanced proton conductivity when compared with the original materials (YbO(OH)Cl and NDTB) with an increase of up to four orders-of-magnitude, reaching 2.36×10(-3) and 1.96×10(-2)  S cm(-1) at 98 % RH and 85 °C for YbO(OH)P and NDTBP, respectively. These values are comparable to the most efficient proton-conducting MOFs. In addition, these two anion-exchanged materials are stable in boiling water, which originates from the strong electrostatic interaction between the H2 PO4 (-) anion and the cationic host framework, showing a clear advance over all the acid-impregnated materials (H2 SO4 @MIL-101, H3 PO4 @MIL-101, and H3 PO4 @Tp-Azo) as practical solid-state fuel-cell electrolytes. This work offers a new general and efficient approach to functionalize 3D-extended frameworks through an anion-exchange process and achieves water-stability with ultra-high proton conductivity above 10(-2)  S cm(-1) .

  2. Surface runoff pollution by cattle slurry and inorganic fertilizer spreading: chemical oxygen demand, ortho-phosphates, and electrical conductivity levels for different buffer strip lengths.

    PubMed

    Núñez-Delgado, A; López-Periago, E; Quiroga-Lago, F; Díaz-Fierros Viqueira, F

    2001-01-01

    As a way of dealing with the removal of pollutants from farming practices generated wastewater in the EU, we investigate the effect of spreading cattle slurry and inorganic fertiliser on 8 x 5 m2 and 8 x 3 m2 areas, referred to surface runoff chemical oxygen demand (COD), ortho-phosphates (o-P) and electrical conductivity (EC) levels, and the efficiency of grass buffer strips of various lengths in removing pollutants from runoff. The experimental plot was a 15% sloped Lolium perenne pasture. Surface runoff was generated by means of a rainfall simulator working at 47 mm h-1 rainfall intensity. Runoff was sampled by using Gerlach-type troughs situated 2, 4, 6 and 8 m downslope from the amended areas. During the first rainfall simulation, COD, o-P and EC levels were consistently higher in the slurry zone, more evidently in the larger amended area. During the second and third rainfall simulations, concentration and mass levels show a downslope drift into the buffer zones, with no clear buffer strip length attenuation. Correlation between runoff and mass drift is clearly higher in the slurry zone. Percentage attenuation in COD and o-P levels, referred to initial slurry concentrations--including rainfall dilution--were higher than 98%, and higher than 90% for EC.

  3. Determination of the kinetic parameters for phospholipase C (Bacillus cereus) on different phospholipid substrates using a chromogenic assay based on the quantitation of inorganic phosphate.

    PubMed

    Hergenrother, P J; Martin, S F

    1997-08-15

    The kinetic parameters of the phosphatidylcholine-preferring phospholipase C from Bacillus cereus (PLCBc) have been evaluated for phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine substrates with a new assay based on the quantitation of inorganic phosphate (Pi). Treatment of the phosphomonoester product of the PLCBc-catalyzed hydrolysis of these phospholipids with alkaline phosphatase releases Pi. This Pi forms a complex with ammonium molybdate that is then reduced by ascorbic acid to provide a blue molybdenum chromogen with an absorbance maximum at 700 nm. This highly sensitive assay may be used to determine accurately less than 5 nmol of Pi in solution. Performing the assay in 96-well plates provides a rapid and convenient method to evaluate a variety of phospholipids as substrates for PLCBc. The assay has been utilized to ascertain the kinetic constants for the PLCBc-catalyzed hydrolysis of 1,2-dihexanoyl-sn-glycero-3-phosphocholine, 1,2-dihexanoyl-sn-glycero-3-phosphoethanolamine, and 1,2-dihexanoyl-sn-glycero-3-phospho-L-serine. It is found that these compounds are substrates for the enzyme with their VmaxS being in the order of phosphatidylcholine > phosphatidylethanolamine > phosphatidylserine.

  4. Compound- and enzyme-specific phosphodiester hydrolysis mechanisms revealed by δ18O of dissolved inorganic phosphate: Implications for marine P cycling

    NASA Astrophysics Data System (ADS)

    Liang, Yuhong; Blake, Ruth E.

    2009-07-01

    We have studied the oxygen isotope signature of inorganic phosphate (P i) generated by hydrolysis of nucleic acid phosphodiester (P-diester) compounds by cell-free enzymes (Deoxyribonuclease 1, Phosphodiesterase 1, Alkaline phosphatase) and microbial cultures at natural isotopic abundances. We demonstrate that the diesterase-catalyzed hydrolytic step leads to incorporation of at least one water O into released P i for a total of two O atoms from water incorporated into P i released from P-diesters. In the presence of Phosphodiesterase 1, 16O is preferentially incorporated into nucleotides released from DNA; whereas 18O is preferentially incorporated into nucleotides released from RNA. A strong consistency between predicted O-isotope regeneration signatures based on results of cell-free enzyme experiments and measured isotopic signatures from independent experiments with E. coli cultures was observed and confirms proposed models for phosphoester hydrolysis. Results from these studies made at natural 18O abundance levels provide a new tool, enzyme-specific O-isotope fractionation, for investigations of organophosphate metabolism and phosphorus cycling pathways in natural aquatic systems.

  5. Protein-inorganic hybrid nanoflowers

    NASA Astrophysics Data System (ADS)

    Ge, Jun; Lei, Jiandu; Zare, Richard N.

    2012-07-01

    Flower-shaped inorganic nanocrystals have been used for applications in catalysis and analytical science, but so far there have been no reports of `nanoflowers' made of organic components. Here, we report a method for creating hybrid organic-inorganic nanoflowers using copper (II) ions as the inorganic component and various proteins as the organic component. The protein molecules form complexes with the copper ions, and these complexes become nucleation sites for primary crystals of copper phosphate. Interaction between the protein and copper ions then leads to the growth of micrometre-sized particles that have nanoscale features and that are shaped like flower petals. When an enzyme is used as the protein component of the hybrid nanoflower, it exhibits enhanced enzymatic activity and stability compared with the free enzyme. This is attributed to the high surface area and confinement of the enzymes in the nanoflowers.

  6. DIFFERENTIAL ACTIVATION OF AP-1 IN HUMAN BLADDER EPITHELIAL CELLS BY INORGANIC AND METHYLATED ARSENICALS

    EPA Science Inventory

    Differential Activation of AP-1 in Human Bladder Epithelial Cells by Inorganic and Methylated Arsenicals

    Zuzana Drobna, Ilona Jaspers, David J. Thomas, and Miroslav Styblo

    ABSTRACT

    Epidemiological studies have linked chronic ingestion of drinking water contai...

  7. DIFFERENTIAL ACTIVATION OF AP-1 IN HUMAN BLADDER EPITHELIAL CELLS BY INORGANIC AND METHYLATED ARSENICALS

    EPA Science Inventory

    Differential Activation of AP-1 in Human Bladder Epithelial Cells by Inorganic and Methylated Arsenicals

    Zuzana Drobna, Ilona Jaspers, David J. Thomas, and Miroslav Styblo

    ABSTRACT

    Epidemiological studies have linked chronic ingestion of drinking water contai...

  8. Selective release of inorganic constituents in broiler manure biochars under different post-activation treatments

    USDA-ARS?s Scientific Manuscript database

    Previous studies determined that poultry litter is a desirable feedstock for activated biochars with enhanced adsorption towards cations. Animal manures such as poultry litter contain a significant fraction of inorganic material that can significantly affect the final physical, chemical and adsorpt...

  9. Activation of Elongation Factor G by Phosphate Analogues

    PubMed Central

    Salsi, Enea; Farah, Elie

    2016-01-01

    EF-G is a universally conserved translational GTPase that promotes the translocation of tRNA and mRNA through the ribosome. EF-G binds to the ribosome in a GTP-bound form and subsequently catalyzes GTP hydrolysis. The contribution of the ribosome-stimulated GTP hydrolysis by EF-G to tRNA/mRNA translocation remains debated. Here, we show that while EF-G•GDP does not stably bind to the ribosome and induce translocation, EFG• GDP in complex with phosphate group analogues BeF3− and AlF4− promotes the translocation of tRNA and mRNA. Furthermore, the rates of mRNA translocation induced by EF-G in the presence of GTP and a non-hydrolysable analogue of GTP, GDP•BeF3−are similar. Our results are consistent with the model suggesting that GTP hydrolysis is not directly coupled to mRNA/tRNA translocation. Hence, GTP binding is required to induce the activated, translocation-competent conformation of EF-G while GTP hydrolysis triggers EF-G release from the ribosome. PMID:27063503

  10. A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, T.

    2008-08-01

    Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH+4, Mg2+, Ca2+, Cl-, Br-, NO-3, HSO-4, and SO2-4 as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol+water+salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

  11. A thermodynamic model of mixed organic-inorganic aerosols to predict activity coefficients

    NASA Astrophysics Data System (ADS)

    Zuend, A.; Marcolli, C.; Luo, B. P.; Peter, Th.

    2008-03-01

    Tropospheric aerosols contain mixtures of inorganic salts, acids, water, and a large variety of organic compounds. Interactions between these substances in liquid mixtures lead to discrepancies from ideal thermodynamic behaviour. By means of activity coefficients, non-ideal behaviour can be taken into account. We present here a thermodynamic model named AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients) that is able to calculate activity coefficients covering inorganic, organic, and organic-inorganic interactions in aqueous solutions over a wide concentration range. This model is based on the activity coefficient model LIFAC by Yan et al. (1999) that we modified and reparametrised to better describe atmospherically relevant conditions and mixture compositions. Focusing on atmospheric applications we considered H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl-, Br-, NO3-, HSO4-, and SO42- as cations and anions and a wide range of alcohols/polyols composed of the functional groups CHn and OH as organic compounds. With AIOMFAC, the activities of the components within an aqueous electrolyte solution are well represented up to high ionic strength. Most notably, a semi-empirical middle-range parametrisation of direct organic-inorganic interactions in alcohol + water + salt solutions strongly improves the agreement between experimental and modelled activity coefficients. At room temperature, this novel thermodynamic model offers the possibility to compute equilibrium relative humidities, gas/particle partitioning and liquid-liquid phase separations with high accuracy. In further studies, other organic functional groups will be introduced. The model framework is not restricted to specific ions or organic compounds and is therefore also applicable for other research topics.

  12. Phosphoinositide and Inositol Phosphate Analysis in Lymphocyte Activation

    PubMed Central

    Sauer, Karsten; Huang, Yina Hsing; Lin, Hongying; Sandberg, Mark; Mayr, Georg W.

    2015-01-01

    Lymphocyte antigen receptor engagement profoundly changes the cellular content of phosphoinositide lipids and soluble inositol phosphates. Among these, the phosphoinositides phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylinositol 3,4,5-trisphosphate (PIP3) play key signaling roles by acting as pleckstrin homology (PH) domain ligands that recruit signaling proteins to the plasma membrane. Moreover, PIP2 acts as a precursor for the second messenger molecules diacylglycerol and soluble inositol 1,4,5-trisphosphate (IP3), essential mediators of PKC, Ras/Erk, and Ca2+ signaling in lymphocytes. IP3 phosphorylation by IP3 3-kinases generates inositol 1,3,4,5-tetrakisphosphate (IP4), an essential soluble regulator of PH domain binding to PIP3 in developing T cells. Besides PIP2, PIP3, IP3, and IP4, lymphocytes produce multiple other phosphoinositides and soluble inositol phosphates that could have important physiological functions. To aid their analysis, detailed protocols that allow one to simultaneously measure the levels of multiple different phosphoinositide or inositol phosphate isomers in lymphocytes are provided here. They are based on thin layer, conventional and high-performance liquid chromatographic separation methods followed by radiolabeling or non-radioactive metal-dye detection. Finally, less broadly applicable nonchromatographic methods for detection of specific phosphoinositide or inositol phosphate isomers are discussed. Support protocols describe how to obtain pure unstimulated CD4+CD8+ thymocyte populations for analyses of inositol phosphate turnover during positive and negative selection, key steps in T cell development. PMID:19918943

  13. Recovery of phosphate from the supernatant of activated sludge pretreated by microwave irradiation through chemical precipitation.

    PubMed

    Xiao, Dean; Huang, Haiming; Jiang, Yang; Ding, Li

    2015-05-14

    This paper presents a technology of releasing phosphate from activated sludge by using a combined process of microwave irradiation and anaerobic stirring, followed by phosphate recovery from the resulting supernatant via chemical precipitation without addition of chemicals, except for a pH regulator. A series of experiments was conducted to examine the effects of microwave irradiation time, sludge solution pH, sludge concentration, and anaerobic stirring time on the release of phosphate. The results revealed that all of these parameters had a significant effect on the release of phosphate via the proposed combined process, and the combination of 180 s of microwave irradiation and 1 h of anaerobic stirring was found to give optimal phosphate release. When the sludge solution was acidized before pretreatment, the phosphate concentration of the supernatant increased rapidly. A 25 g/L sludge concentration was found to be optimal for the release of phosphate, beyond this concentration, there was no increase in the phosphate release. Under the optimal conditions of phosphate release (irradiation time, 180 s; solution pH, 2; sludge concentration, 25 g/L; anaerobic stirring time, 1 h), the total orthophosphate (PT) concentration in the supernatant reached 396 mg/L, accompanied by high concentrations of metal cations such as Ca, Mg, K, Al, and Fe. When the pH of the supernatant was adjusted to 9-10, the recovery efficiency of phosphate reached approximately 95 %. The analysis results indicated that the main components of the collected precipitates were amorphous calcium phosphate and struvite, which can be used as alternate phosphate minerals.

  14. Soil Inorganic Carbon in Deserts: Active Carbon Sink or Inert Reservoir?

    NASA Astrophysics Data System (ADS)

    Monger, H. C.; Cole, D. R.

    2011-12-01

    Soil inorganic carbon is the third largest C pool in the active global carbon cycle, containing at least 800 petagrams of carbon. Although carbonate dissolution-precipitation reactions have been understood for over a century, the role of soil inorganic carbon in carbon sequestration, and in particular pedogenic carbonate, is a deceptively complex process because it involves interdependent connections among climate, plants, microorganisms, silicate minerals, soil moisture, pH, and Ca supply via rain, dust, or in situ weathering. An understanding of soil inorganic carbon as a sink or reservoir also requires examination of the system at local to continental scales and at seasonal to millennial time scales. In desert soils studied in North America, carbon isotope ratios and radiocarbon dates were measured in combination with electron microscopy, lab and field experiments with biological calcite formation, and field measurements of carbon dioxide emissions. These investigations reveal that soil inorganic carbon is both an active sink and a inert reservoir depending on the spatial and temporal scale and source of calcium.

  15. Inorganic and metal nanoparticles and their antimicrobial activity in food packaging applications.

    PubMed

    Hoseinnejad, Mahmoud; Jafari, Seid Mahdi; Katouzian, Iman

    2017-06-03

    Nanotechnology has revolutionized almost all the fields of science and technology, particularly the food packaging industry. Accordingly, some nanoparticles can be used in food contact materials to preserve food products for longer periods. To date, many inorganic and metal nanoparticles have been implemented to synthesize active food packaging materials and to extend the shelf-life of foods. Packaging with nanocomposites containing these nanoparticles offers advantages, such as reduction in the usage of preservatives and higher rate of reactions to inhibit the microbial growth. Nevertheless, the safety issues of employing the metal and inorganic nanoparticles in food packaging are still a major concern and more studies along with clinical trials need to be carried out prior to the mass production of these promising food containers. In this review, we have evaluated recent studies plus the applications of inorganic and metal nanoparticles mostly in food packaging applications along with their antimicrobial properties and reaction mechanisms. Many examples have been provided with the aim of opening new horizons for researchers to implement inorganic and metal nanoparticles in active food packaging field.

  16. Fluoride-containing bioactive glasses inhibit pentose phosphate oxidative pathway and glucose 6-phosphate dehydrogenase activity in human osteoblasts.

    PubMed

    Bergandi, Loredana; Aina, Valentina; Garetto, Stefano; Malavasi, Gianluca; Aldieri, Elisabetta; Laurenti, Enzo; Matera, Lina; Morterra, Claudio; Ghigo, Dario

    2010-02-12

    Bioactive glasses such as Hench's 45S5 (Bioglass) have applications to tissue engineering as well as bone repair, and the insertion of fluoride in their composition has been proposed to enhance their bioactivity. In view of a potential clinical application, we investigated whether fluoride-containing glasses exert toxic effects on human MG-63 osteoblasts, and whether and how fluoride, which is released in the cell culture medium, might play a role in such cytotoxicity. A 24h incubation with 50 microg/ml (12.5 microg/cm(2)) of fluoride-containing bioactive glasses termed HCaCaF(2) (F content: 5, 10 and 15 mol.%) caused the release of lactate dehydrogenase in the extracellular medium (index of cytotoxicity), the accumulation of intracellular malonyldialdehyde (index of lipoperoxidation), and the increase of glutathione consumption. Furthermore, fluoride-containing glasses inhibited the pentose phosphate oxidative pathway and the glucose 6-phosphate dehydrogenase activity. These effects are ascribable to the fluoride content/release of glass powders, since they were mimicked by NaF solutions and were prevented by dimethyl sulfoxide and tempol (two radical scavengers), by superoxide dismutase (a superoxide scavenger), and by glutathione (the most important intracellular antioxidant molecule), but not by apocynin (an inhibitor of NADPH oxidase). The presence of fluoride-containing glasses and NaF caused also the generation of reactive oxygen species, which was prevented by superoxide dismutase and catalase. The data suggest that fluoride released from glasses is the cause of MG-63 cell oxidative damage and is independent of NADPH oxidase activation. Our data provide a new mechanism to explain F(-) ions toxicity: fluoride could trigger, at least in part, an oxidative stress via inhibition of the pentose phosphate oxidative pathway and, in particular, through the oxidative inhibition of glucose 6-phosphate dehydrogenase.

  17. Lithium Iron Phosphate Cell Performance Evaluations for Lunar Extravehicular Activities

    NASA Technical Reports Server (NTRS)

    Reid, Concha

    2007-01-01

    Lithium-ion battery cells are being evaluated for their ability to provide primary power and energy storage for NASA s future Exploration missions. These missions include the Orion Crew Exploration Vehicle, the Ares Crew Launch Vehicle Upper Stage, Extravehicular Activities (EVA, the advanced space suit), the Lunar Surface Ascent Module (LSAM), and the Lunar Precursor and Robotic Program (LPRP), among others. Each of these missions will have different battery requirements. Some missions may require high specific energy and high energy density, while others may require high specific power, wide operating temperature ranges, or a combination of several of these attributes. EVA is one type of mission that presents particular challenges for today s existing power sources. The Portable Life Support System (PLSS) for the advanced Lunar surface suit will be carried on an astronaut s back during eight hour long sorties, requiring a lightweight power source. Lunar sorties are also expected to occur during varying environmental conditions, requiring a power source that can operate over a wide range of temperatures. Concepts for Lunar EVAs include a primary power source for the PLSS that can recharge rapidly. A power source that can charge quickly could enable a lighter weight system that can be recharged while an astronaut is taking a short break. Preliminary results of Al23 Ml 26650 lithium iron phosphate cell performance evaluations for an advanced Lunar surface space suit application are discussed in this paper. These cells exhibit excellent recharge rate capability, however, their specific energy and energy density is lower than typical lithium-ion cell chemistries. The cells were evaluated for their ability to provide primary power in a lightweight battery system while operating at multiple temperatures.

  18. [Inorganic pyrophosphatase activity of the mouse spleen in the immune response and after treatment with bis-phosphonates].

    PubMed

    Komissarenko, S V; Gulaia, N M; Gaĭvoronskaia, G G; Karlova, N P; Tarusova, N B

    1986-01-01

    The inorganic pyrophosphatase activity was determined in different tissues of mice. The immunization of mice by sheep erythrocytes increased the inorganic pyrophosphatase activity of the spleen. The in vivo administration of bisphosphonates (40 mg per 1 g of mass), which are structural analogs of inorganic pyrophosphate (methylene bisphosphonic acid--MBPA, hydroxyethylidene bisphosphonic acid--HEBPA and aminomethylene bisphosphonic acid--AMBPA), inhibited the inorganic pyrophosphatase activity only by MBPA in the thymus and spleen but not in liver. The addition of MBPA, HEBPA as well as of phosphonoacetic acid, imidobisphosphate, bis(phosphonomethyl)-phosphonic acid, MBPA and phosphoric acid monoanhydride to cytosol from the mouse spleen led to the competitive (relative to the [Mg (PPi)2-] complex) inhibition of the inorganic pyrophosphatase activity. AMBPA didn't possess the analogous effect.

  19. Polycarboxylic acids as network modifiers for water durability improvement of inorganic-organic hybrid tin-silico-phosphate low-melting glasses

    SciTech Connect

    Menaa, Bouzid . E-mail: bouzidmenaa@noncry.kuicr.kyoto-u.ac.jp; Mizuno, Megumi; Takahashi, Masahide . E-mail: masahide@noncry.kuicr.kyoto-u.ac.jp; Tokuda, Yomei; Yoko, Toshinobu

    2006-02-15

    We investigated the water durability of the inorganic-organic hybrid tin-silico-phosphate glasses Me{sub 2}SiO-SnO-P{sub 2}O{sub 5} (Me designs the organic methyl group) doped with organic acids (salicylic acid (SA), tartaric acid (TA), citric acid (Canada) and butane tetracarboxylic acid (BTCA)) containing one or more of carboxylic groups per molecule. The structure, thermal properties and durability of the final glasses obtained via a non-aqueous acid-base reaction were discussed owing to the nature and the concentration of the acid added. {sup 29}Si magic angle spinning (MAS) NMR and {sup 31}P MAS NMR spectra, respectively, showed clearly a modification of the network in the host glass matrix of the Me{sub 2}SiO-SnO-P{sub 2}O{sub 5} system. The polycondensation enhancement to form -P-O-Si-O-P- linkages (PSP) and the increase of the Q {sup 2} unit (two bridging oxygens per phosphorus atom) over the Q {sup 3} unit (three bridging oxygens per phosphorus atom) as a function of the acid in the order SA

  20. Temperature Dependence of NMR Relaxation Times of Nucleoside Triphosphates and Inorganic Phosphate in the Isolated Perfused Rat Liver. Effect on Pi Compartmentation

    NASA Astrophysics Data System (ADS)

    Dufour, Sylvie; Thiaudière, Eric; Vidal, Giovanni; Gallis, Jean-Louis; Rousse, Nicole; Canioni, Paul

    1996-11-01

    The effect of temperature on31P NMR spectra from isolated perfused rat livers was studied at 9.4 T. Relaxation times (T1andT2) of nucleoside triphosphates (NTP) and inorganic phosphate (Pi) were determined at 37, 25, 15, and 4°C. Under hypothermic conditions, an unexpected apparent line sharpening in the Pi spectral region and a clear emergence of an additional Pi resonance were observed. This additional signal was assigned to mitochondrial Pi.T1values obtained for cytosolic and mitochondrial Pi at 4°C were 1.14 ± 0.24 s (n= 5) and 0.71 ± 0.18 s (n= 5), respectively. No significant mitochondrial contribution to the Pi resonance was observed at 37°C. Quantification of Pi and NTP liver contents at 37 and 4°C was performed by comparing the perfused liver spectrum and the corresponding perchloric acid extract spectrum. Under experimental conditions of low external Pi (0.12 mM), it was concluded that intracellular Pi was completely NMR-visible at 4 and 37°C. The observation of the mitochondrial Pi signal at 4°C was well explained by an increase in the Pi level within the matrix, in response to the mitochondrial swelling induced by hypothermia, as observed by electron microscopy.T2values for the cytosolic Pi at 37 and 4°C were 17 ± 4 ms (n= 8) and 22 ± 4 ms (n= 10), respectively. Comparison with measured linewidths indicated that line broadening for the main phosphorylated metabolites-including matrix Pi-was the result ofB0field inhomogeneity. The additional broadening of the cytosolic Pi resonance at 4 and 37°C was attributed to pH heterogeneity within the liver.

  1. Joint effect of organic acids and inorganic salts on cloud droplet activation

    NASA Astrophysics Data System (ADS)

    Frosch, M.; Prisle, N. L.; Bilde, M.; Varga, Z.; Kiss, G.

    2010-07-01

    We have investigated CCN properties of internally mixed particles composed of one organic acid (oxalic acid, succinic acid, adipic acid, citric acid, cis-pinonic acid, or nordic reference fulvic acid) and one inorganic salt (sodium chloride or ammonium sulphate). Surface tension and water activity of aqueous model solutions with concentrations relevant for CCN activation were measured using a tensiometer and osmometry, respectively. The measurements were used to calculate Köhler curves, which were compared to measured critical supersaturations of particles with the same chemical compositions, determined with a cloud condensation nucleus counter. Surfactant surface partitioning was not accounted for. For the mixtures containing cis-pinonic acid or fulvic acid, a depression of surface tension was observed, but for the remaining mixtures the effect on surface tension was negligle at concentrations relevant for cloud droplet activation, and water activity was the more significant term in the Köhler equation. The surface tension depression of aqueous solutions containing both organic acid and inorganic salt was approximately the same as or smaller than that of aqueous solutions containing the same mass of the corresponding pure organic acids. Water activity was found to be highly dependent on the type and amount of inorganic salt. Sodium chloride was able to decrease water activity more than ammonium sulphate and both inorganic compounds had a higher effect on water activity than the studied organic acids, and increasing the mass ratio of the inorganic compound led to a decrease in water activity. Water activity measurements were compared to results from the E-AIM model and values estimated from both constant and variable van't Hoff factors to evaluate the performance of these approaches. The correspondence between measuments and estimates was overall good, except for highly concentrated solutions. Critical supersaturations calculated with Köhler theory based on

  2. alpha-Tocopheryl phosphate – an active lipid mediator?

    USDA-ARS?s Scientific Manuscript database

    The vitamin E (alpha-tocopherol, alphaT) derivative, alpha-tocopheryl phosphate (alphaTP), is detectable in small amounts in plasma, tissues, and cultured cells. Studies done in vitro and in vivo suggest that alphaT can become phosphorylated and alphaTP dephosphorylated, suggesting the existence of ...

  3. Nostoc commune UTEX 584 gene expressing indole phosphate hydrolase activity in Escherichia coli.

    PubMed Central

    Xie, W Q; Whitton, B A; Simon, J W; Jäger, K; Reed, D; Potts, M

    1989-01-01

    A gene encoding an enzyme capable of hydrolyzing indole phosphate was isolated from a recombinant gene library of Nostoc commune UTEX 584 DNA in lambda gt10. The gene (designated iph) is located on a 2.9-kilobase EcoRI restriction fragment and is present in a single copy in the genome of N. commune UTEX 584. The iph gene was expressed when the purified 2.9-kilobase DNA fragment, free of any vector sequences, was added to a cell-free coupled transcription-translation system. A polypeptide with an Mr of 74,000 was synthesized when the iph gene or different iph-vector DNA templates were expressed in vitro. When carried by different multicopy plasmids and phagemids (pMP005, pBH6, pB8) the cyanobacterial iph gene conferred an Iph+ phenotype upon various strains of Escherichia coli, including a phoA mutant. Hydrolysis of 5-bromo-4-chloro-3-indolyl phosphate was detected in recombinant E. coli strains grown in phosphate-rich medium, and the activity persisted in assay buffers that contained phosphate. In contrast, indole phosphate hydrolase activity only developed in cells of N. commune UTEX 584, when they were partially depleted of phosphorus, and the activity associated with these cells was suppressed partially by the addition of phosphate to assay buffers. Indole phosphate hydrolase activity was detected in periplasmic extracts from E. coli (Iph+) transformants. Images PMID:2536677

  4. Requirement of a soluble intracellular factor for activation of transient receptor potential A1 by pungent chemicals: role of inorganic polyphosphates.

    PubMed

    Kim, Donghee; Cavanaugh, Eric J

    2007-06-13

    Pungent chemicals such as allyl isothiocyanate (AITC), cinnamaldehyde, and allicin, produce nociceptive sensation by directly activating transient receptor potential A1 (TRPA1) expressed in sensory afferent neurons. In this study, we found that pungent chemicals added to the pipette or bath solution easily activated TRPA1 in cell-attached patches but failed to do so in inside-out or outside-out patches. Thus, a soluble cytosolic factor was required to activate TRPA1. N-Ethylmaleimide, (2-aminoethyl)-methane thiosulfonate, 2-aminoethoxydiphneyl borate, and trinitrophenol, compounds that are known to activate TRPA1, also failed to activate it in inside-out patches. To identify a factor that supports activation of TRPA1 by pungent chemicals, we screened approximately 30 intracellular molecules known to modulate ion channels. Among them, pyrophosphate (PPi) and polytriphosphate (PPPi) were found to support activation of TRPA1 by pungent chemicals. Structure-function studies showed that inorganic polyphosphates (polyP(n), where n = number of phosphates) with at least four phosphate groups were highly effective (polyP4 approximately = polyP65 approximately = polyP45 approximately = polyP25 > PPPi > PPi), with K(1/2) values ranging from 0.2 to 2.8 mM. Inositol-trisphosphate and inositol-hexaphosphate also partially supported activation of TRPA1 by AITC. ATP, GTP, and phosphatidylinositol-4,5-bisphosphate that have three phosphate groups did not support TRPA1 activation. TRPA1 recorded from cell bodies of trigeminal ganglion neurons showed similar behavior with respect to sensitivity to pungent chemicals; no activation was observed in inside-out patches unless a polyphosphate was present. These results show that TRPA1 requires an intracellular factor to adopt a functional conformation that is sensitive to pungent chemicals and suggest that polyphosphates may partly act as such a factor.

  5. Joint effect of organic acids and inorganic salts on cloud droplet activation

    NASA Astrophysics Data System (ADS)

    Frosch, M.; Prisle, N. L.; Bilde, M.; Varga, Z.; Kiss, G.

    2011-04-01

    We have investigated CCN properties of internally mixed particles composed of one organic acid (oxalic acid dihydrate, succinic acid, adipic acid, citric acid, cis-pinonic acid, or Nordic reference fulvic acid) and one inorganic salt (sodium chloride or ammonium sulphate). Surface tension and water activity of aqueous model solutions with concentrations relevant for CCN activation were measured using a tensiometer and osmometry, respectively. The measurements were used to calculate Köhler curves and critical supersaturations, which were compared to measured critical supersaturations of particles with the same chemical compositions, determined with a cloud condensation nucleus counter. Surfactant surface partitioning was not accounted for. For the aqueous solutions containing cis-pinonic acid and fulvic acid, a depression of surface tension was observed, but for the remaining solutions the effect on surface tension was negligible at concentrations relevant for cloud droplet activation. The surface tension depression of aqueous solutions containing both organic acid and inorganic salt was approximately the same as or smaller than that of aqueous solutions containing the same mass of the corresponding pure organic acids. Water activity was found to be highly dependent on the type and amount of inorganic salt. Sodium chloride was able to decrease water activity more than ammonium sulphate and both inorganic salts are predicted to have a smaller Raoult term than the studied organic acids. Increasing the mass ratio of the inorganic salt led to a decrease in water activity. Water activity measurements were compared to results from the E-AIM model and values estimated from both constant and variable van't Hoff factors. The correspondence between measurements and estimates was overall good, except for highly concentrated solutions. Critical supersaturations calculated with Köhler theory based on measured water activity and surface tension, but not accounting for surface

  6. Composite block copolymer stabilized nanoparticles: simultaneous encapsulation of organic actives and inorganic nanostructures.

    PubMed

    Gindy, Marian E; Panagiotopoulos, Athanassios Z; Prud'homme, Robert K

    2008-01-01

    We describe the preparation and characterization of hybrid block copolymer nanoparticles (NPs) for use as multimodal carriers for drugs and imaging agents. Stable, water-soluble, biocompatible poly(ethylene glycol)-block-poly(epsilon-caprolactone) NPs simultaneously co-encapsulating hydrophobic organic actives (beta-carotene) and inorganic imaging nanostructures (Au) are prepared using the flash nanoprecipitation process in a multi-inlet vortex mixer. These composite nanoparticles (CNPs) are produced with tunable sizes between 75 nm and 275 nm, narrow particle size distributions, high encapsulation efficiencies, specified component compositions, and long-term stability. The process is tunable and flexible because it relies on the control of mixing and aggregation timescales. It is anticipated that the technique can be applied to a variety of hydrophobic active compounds, fluorescent dyes, and inorganic nanostructures, yielding CNPs for combined therapy and multimodal imaging applications.

  7. Synthesis of organic/inorganic hybrid gel with acid activated clay after γ-ray radiation.

    PubMed

    Kim, Donghyun; Lee, Hoik; Sohn, Daewon

    2014-08-01

    A hybrid gel was prepared from acid activated clay (AA clay) and acrylic acid by gamma ray irradiation. Irradiated inorganic particles which have peroxide groups act as initiator because it generates oxide radicals by increasing temperature. Inorganic nanoparticles which are rigid part in hybrid gel also contribute to increase the mechanical property as a crosslinker. We prepared two hybrid gels to compare the effect of acid activated treatment of clay; one is synthesized with raw clay particles and another is synthesized with AA clay particles. The composition and structure of AA clay particles and raw clay particles were confirmed by X-ray diffraction (XRD), X-ray fluorescence instrument and surface area analyzer. And chemical and physical property of hybrid gel with different ratios of acrylic acid and clay particle was tested by Raman spectroscope and universal testing machine (UTM). The synthesized hydrogel with 76% gel contents can elongated approximately 1000% of its original size.

  8. Liver X receptor-activating ligands modulate renal and intestinal sodium–phosphate transporters

    PubMed Central

    Caldas, Yupanqui A.; Giral, Hector; Cortázar, Michael A.; Sutherland, Eileen; Okamura, Kayo; Blaine, Judith; Sorribas, Victor; Koepsell, Hermann; Levi, Moshe

    2012-01-01

    Cholesterol is pumped out of the cells in different tissues, including the vasculature, intestine, liver, and kidney, by the ATP-binding cassette transporters. Ligands that activate the liver X receptor (LXR) modulate this efflux. Here we determined the effects of LXR agonists on the regulation of phosphate transporters. Phosphate homeostasis is regulated by the coordinated action of the intestinal and renal sodium–phosphate (NaPi) transporters, and the loss of this regulation causes hyperphosphatemia. Mice treated with DMHCA or TO901317, two LXR agonists that prevent atherosclerosis in ApoE or LDLR knockout mice, significantly decreased the activity of intestinal and kidney proximal tubular brush border membrane sodium gradient-dependent phosphate uptake, decreased serum phosphate, and increased urine phosphate excretion. The effects of DMHCA were due to a significant decrease in the abundance of the intestinal and renal NaPi transport proteins. The same effect was also found in opossum kidney cells in culture after treatment with either agonist. There was increased nuclear expression of the endogenous LXR receptor, a reduction in NaPi4 protein abundance (the main type II NaPi transporter in the opossum cells), and a reduction in NaPi co-transport activity. Thus, LXR agonists modulate intestinal and renal NaPi transporters and, in turn, serum phosphate levels. PMID:21677638

  9. Liver X receptor-activating ligands modulate renal and intestinal sodium-phosphate transporters.

    PubMed

    Caldas, Yupanqui A; Giral, Hector; Cortázar, Michael A; Sutherland, Eileen; Okamura, Kayo; Blaine, Judith; Sorribas, Victor; Koepsell, Hermann; Levi, Moshe

    2011-09-01

    Cholesterol is pumped out of the cells in different tissues, including the vasculature, intestine, liver, and kidney, by the ATP-binding cassette transporters. Ligands that activate the liver X receptor (LXR) modulate this efflux. Here we determined the effects of LXR agonists on the regulation of phosphate transporters. Phosphate homeostasis is regulated by the coordinated action of the intestinal and renal sodium-phosphate (NaPi) transporters, and the loss of this regulation causes hyperphosphatemia. Mice treated with DMHCA or TO901317, two LXR agonists that prevent atherosclerosis in ApoE or LDLR knockout mice, significantly decreased the activity of intestinal and kidney proximal tubular brush border membrane sodium gradient-dependent phosphate uptake, decreased serum phosphate, and increased urine phosphate excretion. The effects of DMHCA were due to a significant decrease in the abundance of the intestinal and renal NaPi transport proteins. The same effect was also found in opossum kidney cells in culture after treatment with either agonist. There was increased nuclear expression of the endogenous LXR receptor, a reduction in NaPi4 protein abundance (the main type II NaPi transporter in the opossum cells), and a reduction in NaPi co-transport activity. Thus, LXR agonists modulate intestinal and renal NaPi transporters and, in turn, serum phosphate levels.

  10. 2-O-α-D-Glucosylglycerol Phosphorylase from Bacillus selenitireducens MLS10 Possessing Hydrolytic Activity on β-D-Glucose 1-Phosphate

    PubMed Central

    Nihira, Takanori; Saito, Yuka; Ohtsubo, Ken’ichi; Nakai, Hiroyuki; Kitaoka, Motomitsu

    2014-01-01

    The glycoside hydrolase family (GH) 65 is a family of inverting phosphorylases that act on α-glucosides. A GH65 protein (Bsel_2816) from Bacillus selenitireducens MLS10 exhibited inorganic phosphate (Pi)-dependent hydrolysis of kojibiose at the rate of 0.43 s−1. No carbohydrate acted as acceptor for the reverse phosphorolysis using β-d-glucose 1-phosphate (βGlc1P) as donor. During the search for a suitable acceptor, we found that Bsel_2816 possessed hydrolytic activity on βGlc1P with a kcat of 2.8 s−1; moreover, such significant hydrolytic activity on sugar 1-phosphate had not been reported for any inverting phosphorylase. The H218O incorporation experiment and the anomeric analysis during the hydrolysis of βGlc1P revealed that the hydrolysis was due to the glucosyl-transferring reaction to a water molecule and not a phosphatase-type reaction. Glycerol was found to be the best acceptor to generate 2-O-α-d-glucosylglycerol (GG) at the rate of 180 s−1. Bsel_2816 phosphorolyzed GG through sequential Bi-Bi mechanism with a kcat of 95 s−1. We propose 2-O-α-d-glucopyranosylglycerol: phosphate β-d-glucosyltransferase as the systematic name and 2-O-α-d-glucosylglycerol phosphorylase as the short name for Bsel_2816. This is the first report describing a phosphorylase that utilizes polyols, and not carbohydrates, as suitable acceptor substrates. PMID:24466148

  11. Intrinsic activation: the relationship between biomass inorganic content and porosity formation during pyrolysis.

    PubMed

    Stratford, James P; Hutchings, Tony R; de Leij, Frans A A M

    2014-05-01

    The utility of pyrolytic carbons is closely related to their porosity and surface area, there is a clear benefit to the development of biomass pyrolysis processes which produce highly porous carbons. The results presented in this work demonstrate that by using biomass precursors with high inorganic content along with specified process conditions, carbons can be consistently produced with specific surface areas between 900 and 1600 m(2)/g. Results from 12 different source materials show that the formation of increased porosity in pyrolytic carbons is strongly associated with the presence of inorganic elements in the precursors including: magnesium, potassium and sulfur. It was found that pyrolysis of macro-algae can produce especially high specific surface area carbons (mean: 1500 m(2)/g), without externally applied activating agents. Using cheap readily available agricultural residues such as oilseed rape straw, pyrolytic carbons can be produced with specific surface areas of around 950 m(2)/g.

  12. RNA 3'-terminal phosphate cyclase activity and RNA ligation in HeLa cell extract.

    PubMed Central

    Filipowicz, W; Konarska, M; Gross, H J; Shatkin, A J

    1983-01-01

    HeLa cell extract contains RNA ligase activity that converts linear polyribonucleotides to covalently closed circles. RNA substrates containing 2',3'-cyclic phosphate and 5'-hydroxyl termini are circularized by formation of a normal 3',5' phosphodiester bond. This activity differs from a previously described wheat germ RNA ligase which circularizes molecules with 2',3'-cyclic and 5' phosphate ends by a 2'-phosphomonester, 3',5'-phosphodiester linkage (Konarska et al., Nature 293, 112-116, 1981; Proc. Natl. Acad. Sci. USA 79, 1474-1478, 1982). The HeLa cell ligase can also utilize molecules with 3'-phosphate ends. However, in this case ligation is preceded by an ATP-dependent conversion of the 3'-terminal phosphate to the 2',3' cyclic form by a novel activity, RNA 3'-terminal phosphate cyclase. Both RNA ligase and RNA 3'-terminal phosphate cyclase activities are also present in extract of Xenopus oocyte nuclei, consistent with a role in RNA processing. Images PMID:6828385

  13. Inorganic nitrogen assimilation in yeasts: alteration in enzyme activities associated with changes in cultural conditions and growth phase.

    PubMed

    Thomulka, K W; Moat, A G

    1972-01-01

    Ammonia assimilation has been investigated in four strains of Saccharomyces cerevisiae by measuring, at intervals throughout the growth cycle, the activities of several enzymes concerned with inorganic ammonia assimilation. Enzyme activities in extracts of cells were compared after growth in complete and defined media. The effect of shift from growth in a complete to growth in a defined medium (and the reverse) was also determined. The absence of aspartase (EC 4.3.1.1, l-aspartate-ammonia lyase) activity, the low specific activities of alanine dehydrogenase, glutamine synthetase [EC 6.3.1.2, l-glutamate-ammonia ligase (ADP)], and the marked increase in activity of the nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase (NADP-GDH) [EC 1.4.1.4, l-glutamate:NADP-oxidoreductase (deaminating)] during the early stages of growth support the conclusion that yeasts assimilate ammonia primarily via glutamate. The NADP-GDH showed a rapid increase in activity just before the initiation of exponential growth, reached a maximum at the mid-exponential stage, and then gradually declined in activity in the stationary phase. The NADP-GDH reached a higher level of activity when the yeasts were grown on the defined medium as compared with complete medium. The nicotinamide adenine dinucleotide-linked glutamate dehydrogenase (NAD-GDH) [EC 1.4.1.2, l-glutamate:NAD-oxidoreductase (deaminating)] showed only slight increases in activity during the exponential phase of growth. There was an inverse relationship in that the NADP-GDH increased in activity as the NAD-GDH decreased. The NAD-GDH activity was higher after growth on the complete medium. The glutamate-oxaloacetate transaminase (EC 2.6.1.1. l-aspartate:2-oxoglutarate aminotransferase) activity rose and fell in parallel with the NADP-GDH, although its specific activity was somewhat lower. Although other ammonia-assimilatory enzymes were demonstrable, it seems unlikely that their combined activities could account

  14. Insights into the activation mechanism of class I HDAC complexes by inositol phosphates

    PubMed Central

    Watson, Peter J.; Millard, Christopher J.; Riley, Andrew M.; Robertson, Naomi S.; Wright, Lyndsey C.; Godage, Himali Y.; Cowley, Shaun M.; Jamieson, Andrew G.; Potter, Barry V. L.; Schwabe, John W. R.

    2016-01-01

    Histone deacetylases (HDACs) 1, 2 and 3 form the catalytic subunit of several large transcriptional repression complexes. Unexpectedly, the enzymatic activity of HDACs in these complexes has been shown to be regulated by inositol phosphates, which bind in a pocket sandwiched between the HDAC and co-repressor proteins. However, the actual mechanism of activation remains poorly understood. Here we have elucidated the stereochemical requirements for binding and activation by inositol phosphates, demonstrating that activation requires three adjacent phosphate groups and that other positions on the inositol ring can tolerate bulky substituents. We also demonstrate that there is allosteric communication between the inositol-binding site and the active site. The crystal structure of the HDAC1:MTA1 complex bound to a novel peptide-based inhibitor and to inositol hexaphosphate suggests a molecular basis of substrate recognition, and an entropically driven allosteric mechanism of activation. PMID:27109927

  15. The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and Aspergillus niger phytase

    NASA Astrophysics Data System (ADS)

    Sperber, C. v.; Tamburini, F.; Brunner, B.; Bernasconi, S. M.; Frossard, E.

    2015-03-01

    Phosphorus (P) is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi) from organic phosphorus compounds (Porg). Phytic acid (IP6) is an important form of Porg in many soils. The enzymatic hydrolysis of IP6 by phytase yields plant available inorganic phosphate (Pi) and less phosphorylated inositol derivates as products. The hydrolysis of organic P-compounds by phosphatases leaves an isotopic imprint on the oxygen isotope composition (δ18O) of released Pi, which might be used to trace P in the environment. This study aims at determining the effect of phytase on the oxygen isotope composition of released Pi. For this purpose, enzymatic assays with histidine acid phytases from wheat and Aspergillus niger were prepared using IP6, adenosine 5'monophosphate (AMP) and glycerophosphate (GPO4) as substrates. For a comparison to the δ18O of Pi released by other extracellular enzymes, enzymatic assays with acid phosphatases from potato and wheat germ with IP6 as substrate were prepared. During the hydrolysis of IP6 by phytase, four Pi are released, and one oxygen atom from water is incorporated into each Pi. This incorporation of oxygen from water into Pi is subject to an apparent inverse isotopic fractionation (ϵ ∼ 6 to 10‰), which is similar to that imparted by acid phosphatase from potato during the hydrolysis of IP6 (ϵ ∼ 7‰) where less than three Pi are released. The incorporation of oxygen from water into Pi during the hydrolysis of AMP and GPO4 by phytase yielded a normal isotopic fractionation (ϵ ∼ -12‰), again similar to values reported for acid phosphatases from potato and wheat germ. We attribute this similarity in ɛ to the same amino acid sequence motif (RHGXRXP) at the active site of these enzymes, which leads to similar reaction mechanisms. We suggest that the striking substrate-dependency of

  16. Looking for phosphate-accumulating bacteria in activated sludge processes: a multidisciplinary approach.

    PubMed

    Tarayre, Cédric; Charlier, Raphaëlle; Delepierre, Anissa; Brognaux, Alison; Bauwens, Julien; Francis, Frédéric; Dermience, Michaël; Lognay, Georges; Taminiau, Bernard; Daube, Georges; Compère, Philippe; Meers, Erik; Michels, Evi; Delvigne, Frank

    2017-03-01

    Over the past decades, an increasing need in renewable resources has progressively appeared. This trend concerns not only fossil fuels but also mineral resources. Wastewater and sewage sludge contain significant concentrations in phosphate and can be considered as a fertilizer source of the utmost importance. In wastewater treatment plants, the biological uptake of phosphate is performed by a specific microbiota: the phosphate-accumulating organisms. These microorganisms are recovered in sewage sludge. Here, we aimed to investigate the occurrence of phosphate accumulators in four wastewater treatment plants. A 16S metagenetic analysis identified the main bacterial phyla extracted from the aerobic treatment: α-Proteobacteria, β-Proteobacteria, and Sphingobacteria. An enrichment stage was performed to stimulate the specific growth of phosphate-accumulating bacteria in an acetate medium. An analysis of metabolic activities of sulfur and phosphorus highlighted strong modifications related to phosphorus and much less distinguishable effects with sulfur. A solid acetate medium containing 5-Br-4-Cl-3-indolyl phosphate was used to select potential phosphate-accumulating bacteria from the enriched consortia. The positive strains have been found to belong in the genera Acinetobacter, Corynebacterium, and Pseudomonas. Finally, electron microscopy was applied to the strains and allowed to confirm the presence of polyphosphate granules. Some of these bacteria contained granules the size of which exceeded 100 nm.

  17. A Relationship Between Microbial Activity in Soils and Phosphate Levels in Tributaries to Lake Champlain

    NASA Astrophysics Data System (ADS)

    Larose, R.; Lee, S.; Lane, T.

    2015-12-01

    Lake Champlain is a large natural freshwater lake. It forms the western boundary of Vermont and drains over half of the state. It is bordered by the state of New York on its western side and drains to the north into Quebec, Canada. Lake Champlain is the source of fresh drinking water for over quarter of a million people and provides for the livelihoods and recreational opportunities of many well beyond its borders. The health of this lake is important. During the summer month's algae blooms plague the lake. These unsightly growths, which affect other aquatic organisms, are the result of excess phosphate flowing into the lake from many sources. Examining whether there is a relationship between microbial activity in the soils bordering tributaries to Lake Champlain and phosphate levels in those tributaries sheds insight into the origins and paths by which phosphate moves into Lake Champlain. Understanding the how phosphate moves into the water system may assist in mitigation efforts.Total Phosphate levels and Total Suspended Solids were measured in second and third order streams in the Lake Champlain Basin over a three-year period. In addition microbial activity was measured within the toe, bank and upland riparian zone areas of these streams during the summer months. In general in areas showing greater microbial activity in the soil(s) there were increased levels of phosphate in the streams.

  18. Formation of directly mutagenic alpha-hydroxy-N-nitrosopiperidine phosphate ester by near-ultraviolet irradiation of N-nitrosopiperidine in phosphate buffer

    SciTech Connect

    Arimoto, S.; Shimada, H.; Ukawa, S.; Mochizuki, M.; Hayatsu, H. )

    1989-08-15

    Previously we found that direct-acting mutagens can be formed from N-nitrosodialkylamines on exposure to near-ultraviolet light in the presence of phosphates. We have now isolated the mutagenic photoproduct formed from N-nitrosopiperidine and inorganic phosphate and identified its structure as the phosphate ester of alpha-hydroxy-N-nitrosopiperidine. This reaction represents a new, non-enzymatic activation of promutagenic N-nitrosodialkylamines.

  19. Sphingomyelinase D activity in model membranes: structural effects of in situ generation of ceramide-1-phosphate.

    PubMed

    Stock, Roberto P; Brewer, Jonathan; Wagner, Kerstin; Ramos-Cerrillo, Blanca; Duelund, Lars; Jernshøj, Kit Drescher; Olsen, Lars Folke; Bagatolli, Luis A

    2012-01-01

    The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy and dynamic light scattering) and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing sphingomyelin were examined. The findings indicate that: 1) ceramide-1-phosphate (particularly lauroyl ceramide-1-phosphate) can be incorporated into sphingomyelin bilayers in a concentration-dependent manner and generates coexistence of liquid disordered/solid ordered domains, 2) the activity of sphingomyelinase D is clearly influenced by the supramolecular organization of its substrate in membranes and, 3) in situ ceramide-1-phosphate generation by enzymatic activity profoundly alters the lateral structure and morphology of the target membranes.

  20. Polymeric enzyme mimics: catalytic activity of ribose-containing polymers for a phosphate substrate.

    PubMed

    Han, Man Jung; Yoo, Kyung Soo; Kim, Young Heui; Chang, Ji Young

    2003-07-07

    The polymers containing ribose rings: poly(5'-acrylamido-5'-deoxy-1',2'-O-isopropylidene-alpha-D-ribose) (11), poly(5'-acrylamido-5'-deoxy-alpha-D-ribose) (12) and poly(5'-acrylamido-5'-deoxy-1'-O-methyl-D-ribose) (13) were prepared as enzyme mimics. Polymers 12 and 13 with free vic-cis-diol groups catalyzed the hydrolysis of phosphodiester (ethyl p-nitrophenyl phosphate and N-methylpyridinium 4-tert-butylcatechol cyclic phosphate) and phosphomonoester substrates with a rate acceleration of 10 approximately equal to 10(3) compared with the uncatalyzed reaction. They also catalyzed the reverse reactions, i.e., the esterification of phosphomonoester to phosphodiester and the phosphorylation of alcohols with phosphate ions. The catalytic activity was attributable to the vic-cis-diols of riboses on polymer chains, which formed hydrogen bonds with two phosphoryl oxygen atoms of phosphates so as to activate the phosphorus atoms to be attacked by nucleophiles. The catalytic activity was negligible for polymer 11 where vic-cis-diol groups were blocked with isopropylidene groups. The catalytic activity was attributable to the vic-cis-diols of riboses on polymer chains, which formed hydrogen bonds with two phosphoryl oxygen atoms of phosphates so as to activate the phosphorus atoms to be attacked by nucleophiles.

  1. Sphingomyelinase D Activity in Model Membranes: Structural Effects of in situ Generation of Ceramide-1-Phosphate

    PubMed Central

    Stock, Roberto P.; Brewer, Jonathan; Wagner, Kerstin; Ramos-Cerrillo, Blanca; Duelund, Lars; Jernshøj, Kit Drescher; Olsen, Lars Folke; Bagatolli, Luis A.

    2012-01-01

    The toxicity of Loxosceles spider venom has been attributed to a rare enzyme, sphingomyelinase D, which transforms sphingomyelin to ceramide-1-phosphate. The bases of its inflammatory and dermonecrotic activity, however, remain unclear. In this work the effects of ceramide-1-phosphate on model membranes were studied both by in situ generation of this lipid using a recombinant sphingomyelinase D from the spider Loxosceles laeta and by pre-mixing it with sphingomyelin and cholesterol. The systems of choice were large unilamellar vesicles for bulk studies (enzyme kinetics, fluorescence spectroscopy and dynamic light scattering) and giant unilamellar vesicles for fluorescence microscopy examination using a variety of fluorescent probes. The influence of membrane lateral structure on the kinetics of enzyme activity and the consequences of enzyme activity on the structure of target membranes containing sphingomyelin were examined. The findings indicate that: 1) ceramide-1-phosphate (particularly lauroyl ceramide-1-phosphate) can be incorporated into sphingomyelin bilayers in a concentration-dependent manner and generates coexistence of liquid disordered/solid ordered domains, 2) the activity of sphingomyelinase D is clearly influenced by the supramolecular organization of its substrate in membranes and, 3) in situ ceramide-1-phosphate generation by enzymatic activity profoundly alters the lateral structure and morphology of the target membranes. PMID:22558302

  2. Attenuation of Phosphate Starvation Responses by Phosphite in Arabidopsis1

    PubMed Central

    Ticconi, Carla A.; Delatorre, Carla A.; Abel, Steffen

    2001-01-01

    When inorganic phosphate is limiting, Arabidopsis has the facultative ability to metabolize exogenous nucleic acid substrates, which we utilized previously to identify insensitive phosphate starvation response mutants in a conditional genetic screen. In this study, we examined the effect of the phosphate analog, phosphite (Phi), on molecular and morphological responses to phosphate starvation. Phi significantly inhibited plant growth on phosphate-sufficient (2 mm) and nucleic acid-containing (2 mm phosphorus) media at concentrations higher than 2.5 mm. However, with respect to suppressing typical responses to phosphate limitation, Phi effects were very similar to those of phosphate. Phosphate starvation responses, which we examined and found to be almost identically affected by both anions, included changes in: (a) the root-to-shoot ratio; (b) root hair formation; (c) anthocyanin accumulation; (d) the activities of phosphate starvation-inducible nucleolytic enzymes, including ribonuclease, phosphodiesterase, and acid phosphatase; and (e) steady-state mRNA levels of phosphate starvation-inducible genes. It is important that induction of primary auxin response genes by indole-3-acetic acid in the presence of growth-inhibitory Phi concentrations suggests that Phi selectively inhibits phosphate starvation responses. Thus, the use of Phi may allow further dissection of phosphate signaling by genetic selection for constitutive phosphate starvation response mutants on media containing organophosphates as the only source of phosphorus. PMID:11706178

  3. Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

    PubMed Central

    Schröder, Heinz C; Müller, Werner E G

    2014-01-01

    Summary Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications. PMID:24991497

  4. Role of phosphate on stability and catalase mimetic activity of cerium oxide nanoparticles.

    PubMed

    Singh, Ragini; Singh, Sanjay

    2015-08-01

    Cerium oxide nanoparticles (CeNPs) have been recently shown to scavenge reactive oxygen and nitrogen species (ROS and RNS) in different experimental model systems. CeNPs (3+) and CeNPs (4+) have been shown to exhibit superoxide dismutase (SOD) and catalase mimetic activity, respectively. Due to their nanoscale dimension, CeNPs are expected to interact with the components of biologically relevant buffers and medium, which could alter their catalytic properties. We have demonstrated earlier that CeNPs (3+) interact with phosphate and lose the SOD activity. However, very little is known about the interaction of CeNPs (4+) with the phosphate and other anions, predominantly present in biological buffers and their effects on the catalase mimetic-activity of these nanoparticles. In this study, we report that catalase mimetic-activity of CeNPs (4+) is resistant to the phosphate anions, pH changes and composition of cell culture media. Given the abundance of phosphate anions in the biological system, it is likely that internalized CeNPs would be influenced by cytoplasmic and nucleoplasmic concentration of phosphate.

  5. CADMIUM PHOSPHATE GLASS

    DOEpatents

    Carpenter, H.W.; Johnson, P.D.

    1963-04-01

    A method of preparing a cadmium phosphate glass that comprises providing a mixture of solid inorganic compounds of cadmuim and phosphate having vaporizable components and heating the resulting composition to a temperature of at least 850 un. Concent 85% C is presented. (AEC)

  6. Physicochemical characteristics and sorption capacities of heavy metal ions of activated carbons derived by activation with different alkyl phosphate triesters

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Liu, Hai; Yang, Shaokun; Zhang, Jian; Zhang, Chenglu; Wu, Haiming

    2014-10-01

    Five alkyl phosphate triesters (APTEs), including trimethyl phosphate (TMP), triethyl phosphate (TEP), triisopropyl phosphate (TPP), tributyl phosphate (TBP) and trioctyl phosphate (TOP), were used as activating agents for preparing activated carbons (AC-APTEs) with high surface acidity and metal ion sorption capacity. N2 adsorption/desorption isotherms, surface morphologies, elemental compositions, results of Boehm's titration and sorption capacities of heavy metal ions of the carbons were investigated. AC-APTEs contained much more acidic groups and exhibited much less surface area (<500 m2/g) in comparison with activated carbon (AC-PPA, 1145 m2/g) obtained from phosphoric acid activation. For the AC-APTEs, AC-TOP had the highest surface area (488 m2/g), AC-TMP showed the highest yield (41.1%), and AC-TBP possessed the highest acidic groups (2.695 mmol/g), oxygen content (47.0%) and metal ion sorption capacities (40.1 mg/g for Ni(II) and 53.5 mg/g for Cd(II)). For the carbons, AC-APTEs showed much larger Ni(II) and Cd(II) sorption capacities than AC-PPA, except AC-TPP. The differences of the carbons in the physicochemical and sorption properties suggested surface chemistry of the carbons was the main factor influencing their sorption capacities whereas the pore structure played a secondary role.

  7. Determination of trace elements in rock phosphates by various neutron activation methods

    SciTech Connect

    Hamamo, H.; Landsberger, S.; Panno, S.; Harbottle, G.

    1994-12-31

    Recent interest in the application of rock phosphates in industry and agriculture has resulted in the determination of radionuclides and heavy metals in various worldwide deposits. Phosphate rocks have many applications in the processes of detergents, rubber and dye stuffs, and phosphate fertilizer. Phosphorous is widely distributed in nature and never found in an uncombined form. Apatite is a phosphate mineral chiefly occurring as veins or intrusions in igneous rocks, typically having several thousandths to a few hundredths of a percent of uranium. Thus most produced fertilizers contain appreciable amounts of uranium and its radioactive progenies. Elevated concentration of arsenic, cadmium, and zinc as well as rare earths are also found in phosphate minerals. We have begun a project investigating the possible role that fertilizers have on the ecosystems. As an initial step, a series of standard reference phosphate reference materials are being determined for uranium and heavy-metal content using neutron activation analysis (NAA). Due to the high concentrations of uranium (>100 ppm) and its fission products, a careful evaluation of various NAA methods is being undertaken. Further complications in achieving good detection limits in the lower energy region is the high background associated with the bremsstrahlung radiation arising from {sup 32}P from the {sup 31}P(n,{gamma}) reaction.

  8. Mechanisms for solubilization of various insoluble phosphates and activation of immobilized phosphates in different soils by an efficient and salinity-tolerant Aspergillus niger strain An2.

    PubMed

    Li, Xiaolong; Luo, Lijin; Yang, Jinshui; Li, Baozhen; Yuan, Hongli

    2015-03-01

    Mechanisms for solubilization of different types of phosphates and activation of immobilized phosphates in different types of soils by an efficient fungal strain An2 were explored and evaluated in this study. An2 was isolated from a Chinese cabbage rhizosphere soil and identified as Aspergillus niger. It could fast release up to 1722, 2066, and 2356 mg L(-1) of soluble phosphorus (P) from 1 % Ca3(PO4)2, Mg3(PO4)2, and AlPO4 (Ca-P, Mg-P, and Al-P) and 215 and 179 mg L(-1) from 0.5 % FePO4 and rock phosphate (Fe-P and RP), respectively. HPLC assay demonstrated that An2 mainly secreted oxalic acid to solubilize Ca-P, Mg-P, Al-P, and Fe-P whereas secreted tartaric acid to solubilize RP. Furthermore, An2 could tolerate salinity up to 4 % NaCl without impairing its phosphate-solubilizing ability. The simulation experiments validated that An2 was able to effectively activate immobilized phosphates in general calcareous, acidic, as well as saline-alkali soils with high total P content. This study shows new insights into the mechanisms for microbial solubilization of different types of phosphates and supports the future application of strain An2 in different types of soils to effectively activate P for plants.

  9. Enhanced ozone loss by active inorganic bromine chemistry in the tropical troposphere

    NASA Astrophysics Data System (ADS)

    Le Breton, Michael; Bannan, Thomas J.; Shallcross, Dudley E.; Khan, M. Anwar; Evans, Mathew J.; Lee, James; Lidster, Richard; Andrews, Stephen; Carpenter, Lucy J.; Schmidt, Johan; Jacob, Daniel; Harris, Neil R. P.; Bauguitte, Stephane; Gallagher, Martin; Bacak, Asan; Leather, Kimberley E.; Percival, Carl J.

    2017-04-01

    Bromine chemistry, particularly in the tropics, has been suggested to play an important role in tropospheric ozone loss although a lack of measurements of active bromine species impedes a quantitative understanding of its impacts. Recent modelling and measurements of bromine monoxide (BrO) by Wang et al. (2015) have shown current models under predict BrO concentrations over the Pacific Ocean and allude to a missing source of BrO. Here, we present the first simultaneous aircraft measurements of atmospheric bromine monoxide, BrO (a radical that along with atomic Br catalytically destroys ozone) and the inorganic Br precursor compounds HOBr, BrCl and Br2 over the Western Pacific Ocean from 0.5 to 7 km. The presence of 0.17-1.64 pptv BrO and 3.6-8 pptv total inorganic Br from these four species throughout the troposphere causes 10-20% of total ozone loss, and confirms the importance of bromine chemistry in the tropical troposphere; contributing to a 6 ppb decrease in ozone levels due to halogen chemistry. Observations are compared with a global chemical transport model and find that the observed high levels of BrO, BrCl and HOBr can be reconciled by active multiphase oxidation of halide (Br- and Cl-) by HOBr and ozone in cloud droplets and aerosols. Measurements indicate that 99% of the instantaneous free Br in the troposphere up to 8 km originates from inorganic halogen photolysis rather than from photolysis of organobromine species.

  10. Practical tethering of vitamin B1 on a silica surface via its phosphate group and evaluation of its activity.

    PubMed

    Vartzouma, Ch; Louloudi, M; Butler, I S; Hadjiliadis, N

    2002-03-07

    A convenient immobilization of thiamine pyrophosphate molecules on a silica surface through the phosphate group is developed, leading to a very active heterogenized biocatalyst for pyruvate decarboxylation.

  11. Partially phosphorylated Pho4 activates transcription of a subset of phosphate-responsive genes.

    PubMed

    Springer, Michael; Wykoff, Dennis D; Miller, Nicole; O'Shea, Erin K

    2003-11-01

    A cell's ability to generate different responses to different levels of stimulus is an important component of an adaptive environmental response. Transcriptional responses are frequently controlled by transcription factors regulated by phosphorylation. We demonstrate that differential phosphorylation of the budding yeast transcription factor Pho4 contributes to differential gene expression. When yeast cells are grown in high-phosphate growth medium, Pho4 is phosphorylated on four critical residues by the cyclin-CDK complex Pho80-Pho85 and is inactivated. When yeast cells are starved for phosphate, Pho4 is dephosphorylated and fully active. In intermediate-phosphate conditions, a form of Pho4 preferentially phosphorylated on one of the four sites accumulates and activates transcription of a subset of phosphate-responsive genes. This Pho4 phosphoform binds differentially to phosphate-responsive promoters and helps to trigger differential gene expression. Our results demonstrate that three transcriptional outputs can be generated by a pathway whose regulation is controlled by one kinase, Pho80-Pho85, and one transcription factor, Pho4. Differential phosphorylation of Pho4 by Pho80-Pho85 produces phosphorylated forms of Pho4 that differ in their ability to activate transcription, contributing to multiple outputs.

  12. Partially Phosphorylated Pho4 Activates Transcription of a Subset of Phosphate-Responsive Genes

    PubMed Central

    Miller, Nicole

    2003-01-01

    A cell's ability to generate different responses to different levels of stimulus is an important component of an adaptive environmental response. Transcriptional responses are frequently controlled by transcription factors regulated by phosphorylation. We demonstrate that differential phosphorylation of the budding yeast transcription factor Pho4 contributes to differential gene expression. When yeast cells are grown in high-phosphate growth medium, Pho4 is phosphorylated on four critical residues by the cyclin–CDK complex Pho80–Pho85 and is inactivated. When yeast cells are starved for phosphate, Pho4 is dephosphorylated and fully active. In intermediate-phosphate conditions, a form of Pho4 preferentially phosphorylated on one of the four sites accumulates and activates transcription of a subset of phosphate-responsive genes. This Pho4 phosphoform binds differentially to phosphate-responsive promoters and helps to trigger differential gene expression. Our results demonstrate that three transcriptional outputs can be generated by a pathway whose regulation is controlled by one kinase, Pho80–Pho85, and one transcription factor, Pho4. Differential phosphorylation of Pho4 by Pho80–Pho85 produces phosphorylated forms of Pho4 that differ in their ability to activate transcription, contributing to multiple outputs. PMID:14624238

  13. Spatial and Temporal Variability in the Concentration and Turnover of the Inorganic Phosphate and Adenosine-5'-triphosphate pools in the North Pacific Subtropical Gyre

    NASA Astrophysics Data System (ADS)

    Björkman, Karin; Church, Matthew; Karl, David

    2015-04-01

    The microbial community's utilization of inorganic phosphate (Pi) and adenosine-5'-triphosphate (ATP) as a function of the Pi pool concentration was studied over a multi-year period at Station ALOHA (22.75˚N, 158˚W) in the North Pacific Subtropical Gyre (NPSG). Additionally, the spatial variability in these same properties was investigated along an east-west transect from California to Hawaii in the Fall of 2014. We used radiotracer techniques to determine the turnover times of the Pi or ATP pools respectively, and assessed the net production of dissolved organic phosphorus, and Pi hydrolysis rate from ATP. Pi concentrations in the upper water column at Station ALOHA are temporally highly dynamic, with periods of <10 nM-P to near 200 nM-P recorded within the top 50 m over the past decades of observations. During the California to Hawaii transect Pi concentrations showed a similarly large range (<10 to >200 nM-P), emphasizing the spatially and temporally mosaic nature of the upper ocean of this large biome. The Pi-pool turnover time ranged from a few hours to several weeks, and was strongly correlated with measured Pi pool concentrations (r2=0.8; n=30 Station ALOHA; n=15 transect). The calculated Pi uptake rates at Station ALOHA averaged 3.7±1.3 nM-P d-1 (n=30), reflecting the typically low maximum Pi uptake rates of the Prochlorococcus dominated community and the predominantly non-limiting Pi conditions. The Pi uptake rates along the transect were more variable than Station ALOHA (averaging 9.2±4.7 nM=P d-1, n=15), possibly due to a more diverse planktonic community structure, including stations with elevated concentrations of chlorophyll and primary productivity. The turnover time of the dissolved ATP pool was typically substantially shorter than for the Pi-pool (2-5 days at Station ALOHA; 0.3-2.5 days along the transect), likely reflecting its low nanomolar to picomolar ambient pool concentrations. However, at stations with the lowest SRP concentrations the

  14. Microbial Group Specific Uptake Kinetics of Inorganic Phosphate and Adenosine-5′-Triphosphate (ATP) in the North Pacific Subtropical Gyre

    PubMed Central

    Björkman, Karin; Duhamel, Solange; Karl, David M.

    2012-01-01

    We investigated the concentration dependent uptake of inorganic phosphate (Pi) and adenosine-5′-triphosphate (ATP) in microbial populations in the North Pacific Subtropical Gyre (NPSG). We used radiotracers to measure substrate uptake into whole water communities, differentiated microbial size classes, and two flow sorted groups; Prochlorococcus (PRO) and non-pigmented bacteria (NPB). The Pi concentrations, uptake rates, and Pi pool turnover times (Tt) were (mean, ±SD); 54.9 ± 35.0 nmol L−1 (n = 22), 4.8 ± 1.9 nmol L−1 day−1 (n = 19), and 14.7 ± 10.2 days (n = 19), respectively. Pi uptake into >2 μm cells was on average 12 ± 7% (n = 15) of the total uptake. The kinetic response to Pi (10–500 nmol L−1) was small, indicating that the microorganisms were close to their maximum uptake velocity (Vmax). Vmax averaged 8.0 ± 3.6 nmol L−1 day−1 (n = 19) in the >0.2 μm group, with half saturation constants (Km) of 40 ± 28 nmol L−1 (n = 19). PRO had three times the cell specific Pi uptake rate of NPB, at ambient concentrations, but when adjusted to cells L−1 the rates were similar, and these two groups were equally competitive for Pi. The Tt of γ-P-ATP in the >0.2 μm group were shorter than for the Pi pool (4.4 ± 1.0 days; n = 6), but this difference diminished in the larger size classes. The kinetic response to ATP was large in the >0.2 μm class with Vmax exceeding the rates at ambient concentrations (mean 62 ± 27 times; n = 6) with a mean Vmax for γ-P-ATP of 2.8 ± 1.0 nmol L−1 day−1, and Km at 11.5 ± 5.4 nmol L−1 (n = 6). The NPB contribution to γ-P-ATP uptake was high (95 ± 3%, n = 4) at ambient concentrations but decreased to ∼50% at the highest ATP amendment. PRO had Km values 5–10 times greater than NPB. The above indicates that PRO and NPB were in close competition in terms of Pi acquisition

  15. Simultaneous removal of ammonium and phosphate by alkaline-activated and lanthanum-impregnated zeolite.

    PubMed

    He, Yinhai; Lin, Hai; Dong, Yingbo; Liu, Quanli; Wang, Liang

    2016-12-01

    Simultaneous ammonium and phosphate removal characteristics and mechanism, as well as the major influencing factors, such as pH, temperature and co-existing ions, onto NaOH-activated and lanthanum-impregnated zeolite (NLZ) were investigated. The phosphate adsorption increases from 0.2 mg g(-1) for natural zeolite up to 8.96 mg g(-1) for NLZ, while only a slight decrease on the ammonium adsorption capacity from 23.9 mg g(-1) for NaOH-activated zeolite to 21.2 mg g(-1) for NLZ was observed. The ammonium and phosphate adsorption showed little pH dependence in the range from pH 3 to 7, while it decreased sharply with the pH increased above pH 7. Adsorption of ammonium and phosphate could be well described by the pseudo-second-order model and the process was mainly governed by intra-particle diffusion. The Langmuir and Freundlich model can be acceptably applied to fit the experimental data, which suggested that adsorption was caused by both the monolayer and homogeneous coverage at specific and equal affinity sites available NLZ. The underlying mechanism for the specific adsorption of phosphate by NLZ was revealed with the aid of SEM-EDS, XPS, and FTIR analysis, and the formation of (LaO)(OH)PO2 was verified to be the dominant pathway for selective phosphate adsorption by lanthanum-impregnated zeolite. While the removal mechanism of ammonium could be well interpreted by SEM-EDS, FTIR and ICP analysis, and ion-exchange was expected to be the main removal process for ammonium. The results indicate that NLZ could efficiently and simultaneously remove low concentration of ammonium and phosphate from contaminated waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. 77 FR 5061 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Inorganic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-01

    ...; Inorganic Arsenic Standard ACTION: Notice. SUMMARY: The Department of Labor (DOL) is submitting the..., ``Inorganic Arsenic Standard,'' to the Office of Management and Budget (OMB) for review and approval for... . SUPPLEMENTARY INFORMATION: The purpose of the Inorganic Arsenic Standard is to protect workers from the adverse...

  17. Immobilization of inorganic pyrophosphatase on nanodiamond particles retaining its high enzymatic activity.

    PubMed

    Rodina, Elena V; Valueva, Anastasiya V; Yakovlev, Ruslan Yu; Vorobyeva, Nataliya N; Kulakova, Inna I; Lisichkin, Georgy V; Leonidov, Nikolay B

    2015-12-21

    Nanodiamond (ND) particles are popular platforms for the immobilization of molecular species. In the present research, enzyme Escherichia coli inorganic pyrophosphatase (PPase) was immobilized on detonation ND through covalent or noncovalent bonding and its enzymatic activity was characterized. Factors affecting adsorption of PPase such as ND size and surface chemistry were studied. The obtained material is a submicron size association of ND particles and protein molecules in approximately equal amounts. Both covalently and noncovalently immobilized PPase retains a significant enzymatic activity (up to 95% of its soluble form) as well as thermostability. The obtained hybrid material has a very high enzyme loading capacity (∼1 mg mg(-1)) and may be considered as a promising delivery system of biologically active proteinaceous substances, particularly in the treatment of diseases such as calcium pyrophosphate crystal deposition disease and related pathologies. They can also be used as recoverable heterogeneous catalysts in the traditional uses of PPase.

  18. Synthesis and characterization of inorganic polymers from the alkali activation of an aluminosilicate

    NASA Astrophysics Data System (ADS)

    González, C. P.; Montaño, A. M.; González, A. K.; Ríos, C. A.

    2014-06-01

    This paper presents the results of the synthesis and characterization of inorganic polymers (IP) from aluminosilicates: bentonite (BT) and pumice (PP). The synthesis of IP, was carried out by two methods involving alkaline activation, at room temperature and 80 ± 5 °C, using as activating agent sodium silicate both commercial and analytical (Na2SiO3). Sodium hydroxide (NaOH) at 3 M, 7 M and 12 M was added. A lower degree of polymerization was obtained by using analytical precursors subjected to room temperature and 80 ± 5°C. Replacement of heating by the use of the commercial activating agent with greater alkalinity allows the formation of a 3D network. The materials were structurally characterized by FTIR spectroscopy with Attenuated Reflectance (ATR), Scanning Electron Microscope (SEM) and X -ray diffraction (DRX).

  19. Inositol phosphates and phosphoinositides activate insulin-degrading enzyme, while phosphoinositides also mediate binding to endosomes.

    PubMed

    Song, Eun Suk; Jang, HyeIn; Guo, Hou-Fu; Juliano, Maria A; Juliano, Luiz; Morris, Andrew J; Galperin, Emilia; Rodgers, David W; Hersh, Louis B

    2017-04-04

    Insulin-degrading enzyme (IDE) hydrolyzes bioactive peptides, including insulin, amylin, and the amyloid β peptides. Polyanions activate IDE toward some substrates, yet an endogenous polyanion activator has not yet been identified. Here we report that inositol phosphates (InsPs) and phosphatdidylinositol phosphates (PtdInsPs) serve as activators of IDE. InsPs and PtdInsPs interact with the polyanion-binding site located on an inner chamber wall of the enzyme. InsPs activate IDE by up to ∼95-fold, affecting primarily Vmax The extent of activation and binding affinity correlate with the number of phosphate groups on the inositol ring, with phosphate positional effects observed. IDE binds PtdInsPs from solution, immobilized on membranes, or presented in liposomes. Interaction with PtdInsPs, likely PtdIns(3)P, plays a role in localizing IDE to endosomes, where the enzyme reportedly encounters physiological substrates. Thus, InsPs and PtdInsPs can serve as endogenous modulators of IDE activity, as well as regulators of its intracellular spatial distribution.

  20. Characteristics of Zinc Phosphate Coating Activated by Different Concentrations of Nickel Acetate Solution

    NASA Astrophysics Data System (ADS)

    Abdalla, Khalid; Zuhailawati, H.; Rahmat, Azmi; Azizan, A.

    2017-02-01

    Activation pretreatment with nickel acetate solution at various concentrations was performed prior to the phosphating step to enhance the corrosion resistance of carbon steel substrates. The activation solution was studied over various concentrations: 10, 50, and 100 g/L. The effects of these concentrations on surface characteristics and microstructural evolution of the coated samples were characterized by scanning electron microscopy and energy-dispersive spectroscopy. The electrochemical behavior was evaluated using potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion test in a 3.5 pct NaCl solution. Significant increases in the nucleation sites and surface coverage of zinc phosphate coating were observed as the concentration of activation solution reached 50 g/L. The electrochemical analysis revealed that the activation treatment with 50 g/L nickel acetate solution significantly improved the protection ability of the zinc phosphate coating. The corrosion current density of activated phosphate coating with 50 g/L was reduced by 64.64 and 13.22 pct, compared to the coatings obtained with activation solutions of 10 and 100 g/L, respectively.

  1. A grit separation module for inorganic matter removal from activated sludge: investigation on characteristics of split sludge from the module.

    PubMed

    Chen, You-Peng; Guo, Jin-Song; Wang, Jing; Yan, Peng; Ji, Fang-Ying; Fang, Fang; Dong, Yang

    2016-12-01

    A grit separation module was developed to prevent the accumulation of inorganic solids in activated sludge systems, and it achieved effective separation of organic matter and inorganic solids. To provide technical and theoretical support for further comprehensive utilization of split sludge (underflow and overflow sludge from the separation module), the characteristics of split sludge were investigated. The settling and dewatering properties of the underflow sludge were excellent, and it had high inorganic matter content, whereas the overflow sludge had higher organic matter content. The most abundant inorganic constituent was SiO2 (59.34%), and SiO2, Al2O3, and Fe2O3 together accounted for 79.53% of the inorganic matter in the underflow sludge. The mass ratio of Fe2O3, CaO, and MgO to SiO2 and Al2O3 was 0.245 in the inorganic component of the underflow sludge. The underflow sludge had the beneficial characteristics of simple treatment and disposal, and it was suitable for use as a base raw material for ceramsite production. The overflow sludge with higher organic matter content was constantly returned from the separation module to the wastewater treatment system, gradually improving the volatile suspended solid/total suspended solid ratio of the activated sludge in the wastewater treatment system.

  2. Inorganic phosphorus fertilizer ameliorates maize growth by reducing metal uptake, improving soil enzyme activity and microbial community structure.

    PubMed

    Wu, Wencheng; Wu, Jiahui; Liu, Xiaowen; Chen, Xianbin; Wu, Yingxin; Yu, Shixiao

    2017-09-01

    Recently, several studies have showed that both organic and inorganic fertilizers are effective in immobilizing heavy metals at low cost, in comparison to other remediation strategies for heavy metal-contaminated farmlands. A pot trial was conducted in this study to examine the effects of inorganic P fertilizer and organic fertilizer, in single application or in combination, on growth of maize, heavy metal availabilities, enzyme activities, and microbial community structure in metal-contaminated soils from an electronic waste recycling region. Results showed that biomass of maize shoot and root from the inorganic P fertilizer treatments were respectively 17.8 and 10.0 folds higher than the un-amended treatments (CK), while the biomass in the organic fertilizer treatments was only comparable to the CK. In addition, there were decreases of 85.0% in Cd, 74.3% in Pb, 66.3% in Cu, and 91.9% in Zn concentrations in the roots of maize grown in inorganic P fertilizer amended soil. Consistently, urease and catalase activities in the inorganic P fertilizer amended soil were 3.3 and 2.0 times higher than the CK, whereas no enhancement was observed in the organic fertilizer amended soil. Moreover, microbial community structure was improved by the application of inorganic P fertilizer, but not by organic fertilizer; the beneficial microbial groups such as Kaistobacter and Koribacter were most frequently detected in the inorganic P fertilizer amended soil. The negligible effect from the organic fertilizer might be ascribed to the decreased pH value in soils. The results suggest that the application of inorganic P fertilizer (or in combination with organic fertilizer) might be a promising strategy for the remediation of heavy metals contaminated soils in electronic waste recycling region. Copyright © 2017. Published by Elsevier Inc.

  3. TWEAK favors phosphate-induced calcification of vascular smooth muscle cells through canonical and non-canonical activation of NFκB

    PubMed Central

    Hénaut, L; Sanz, A B; Martin-Sanchez, D; Carrasco, S; Villa-Bellosta, R; Aldamiz-Echevarria, G; Massy, Z A; Sanchez-Nino, M D; Ortiz, A

    2016-01-01

    Vascular calcification (VC) is associated with increased cardiovascular mortality in aging, chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM) and atherosclerosis. TNF-like weak inducer of apoptosis (TWEAK) recently emerged as a new biomarker for the diagnosis and prognosis of cardiovascular diseases. TWEAK binding to its functional receptor Fn14 was reported to promote several steps of atherosclerotic plaque progression. However, no information is currently available on the role of TWEAK/Fn14 on the development of medial calcification, which is highly prevalent in aging, CKD and T2DM. This study explored the involvement of TWEAK in human vascular smooth muscle cells (h-VSMCs) calcification in vitro. We report that TWEAK binding to Fn14 promotes inorganic phosphate-induced h-VSMCs calcification, favors h-VSMCs osteogenic transition, decreasing acta2 and myh11 and increasing bmp2 mRNA and tissue non-specific alkaline phosphatase (TNAP), and increases MMP9 activity. Blockade of the canonical NFκB pathway reduced by 80% TWEAK pro-calcific properties and decreased osteogenic transition, TNAP and MMP9 activity. Blockade of non-canonical NFκB signaling by a siRNA targeting RelB reduced by 20% TWEAK pro-calcific effects and decreased TWEAK-induced loss of h-VSMCs contractile phenotype and MMP9 activity, without modulating bmp2 mRNA or TNAP activity. Inhibition of ERK1/2 activation by a MAPK kinase inhibitor did not influence TWEAK pro-calcific properties. Our results suggest that TWEAK/Fn14 directly favors inorganic phosphate-induced h-VSMCs calcification by activation of both canonical and non-canonical NFκB pathways. Given the availability of neutralizing anti-TWEAK strategies, our study sheds light on the TWEAK/Fn14 axis as a novel therapeutic target in the prevention of VC. PMID:27441657

  4. Hydrous iron oxide modified diatomite as an active filtration medium for phosphate capture.

    PubMed

    Wang, Zhe; Lin, Yan; Wu, Deyi; Kong, Hainan

    2016-02-01

    A simple method to functionalize diatomite with hydrous iron oxide was attempted and its performance as a new active filtration material to remove and recover phosphate from water was investigated under varying solution conditions. The Langmuir phosphate adsorption capacity increased from 0.6 mgP/g for raw diatomite to 4.89, 14.71, 25.02 mgP/g for hydrous iron oxide modified diatomite (HIOMD), depending on the amount of iron loaded. Loading of hydrous iron oxide caused the increase in true and bulk density and a decline in filtration rate, but to a lesser extent. It was shown that the HIOMD product with suitable iron content could retain a good filtration performance with a greatly increased adsorption capacity for phosphate. The phosphate adsorption increased by decreasing pH and by increasing ionic strength at high pH levels. The adsorption process was interpreted by ligand exchange. Coexisting oxyanions of sulfate, nitrate, citrate, carbonate, silicate and humic acid showed different effects on phosphate fixation but it was presumed that their influence at their concentrations and pH levels commonly encountered in effluent or natural waters was limited, i.e., HIOMD had a reasonably good selectivity. Results in repeated adsorption, desorption and regeneration experiment showed that the adsorbed phosphate could be recovered and the material could be reused after regeneration. The column test showed that HIOMD could be potentially utilized as an adsorption filtration medium for phosphate removal and recovery from water. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Dual activity of quinolinate synthase: triose phosphate isomerase and dehydration activities play together to form quinolinate.

    PubMed

    Reichmann, Debora; Couté, Yohann; Ollagnier de Choudens, Sandrine

    2015-10-27

    Quinolinate synthase (NadA) is an Fe4S4 cluster-containing dehydrating enzyme involved in the synthesis of quinolinic acid (QA), the universal precursor of the essential coenzyme nicotinamide adenine dinucleotide. The reaction catalyzed by NadA is not well understood, and two mechanisms have been proposed in the literature that differ in the nature of the molecule (DHAP or G-3P) that condenses with iminoaspartate (IA) to form QA. In this article, using biochemical approaches, we demonstrate that DHAP is the triose that condenses with IA to form QA. The capacity of NadA to use G-3P is due to its previously unknown triose phosphate isomerase activity.

  6. Controlling the release of active compounds from the inorganic carrier halloysite

    NASA Astrophysics Data System (ADS)

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M.

    2014-05-01

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles.

  7. Controlling the release of active compounds from the inorganic carrier halloysite

    SciTech Connect

    Tescione, F.; Buonocore, G. G.; Stanzione, M.; Oliviero, M.; Lavorgna, M.

    2014-05-15

    Halloysite (HNTs), a natural material characterized by a nanotube structure, has been used as an inorganic carrier of active compounds in several applications from medicine to anticorrosion coatings. In this present work, vanillin (VAN) used as a antimicrobial model, has been encapsulated within HNTs for exploiting its applicability in the active food packaging sector. The molecule release rate has been controlled by crosslinking at the tube ends the loaded vanillin with copper ions, thus producing a stopper network. The vanillin-loaded HNTs were characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis. The antimicrobial release kinetics from the loaded nanoparticles (VAN/HNTs) in water was investigated using UV-vis spectroscopy. The results show that the vanillin crosslinked with cupper ions is a feasible method to tailor the release rate of antimicrobial model from HTNs nanoparticles.

  8. Biodegradable Inorganic Nanovector: Passive versus Active Tumor Targeting in siRNA Transportation.

    PubMed

    Park, Dae-Hwan; Cho, Jaeyong; Kwon, Oh-Joon; Yun, Chae-Ok; Choy, Jin-Ho

    2016-03-24

    The biodegradable inorganic nanovector based on a layered double hydroxide (LDH) holds great promise for gene and drug delivery systems. However, in vivo targeted delivery of genes through LDH still remains a key challenge in the development of RNA interference therapeutics. Here, we describe in vivo and in vitro delivery system for Survivin siRNA (siSurvivin) assembled with passive LDH with a particle size of 100 nm or active LDH conjugated with a cancer overexpressing receptor targeting ligand, folic acid (LDHFA), conferring them an ability to target the tumor by either EPR-based clathrin-mediated or folate receptor-mediated endocytosis. When not only transfected into KB cells but also injected into xenograft mice, LDHFA/siSurvivin induced potent gene silencing at mRNA and protein levels in vitro, and consequently achieved a 3.0-fold higher suppression of tumor volume than LDH/siSurvivin in vivo. This anti-tumor effect was attributed to a selectively 1.2-fold higher accumulation of siSurvivin in tumor tissue compared with other organs. Targeting to the tumor with inorganic nanovector can guide and accelerate an evolution of next-generation theranosis system. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Benzylic Phosphates in Friedel-Crafts Reactions with Activated and Unactivated Arenes: Access to Polyarylated Alkanes.

    PubMed

    Pallikonda, Gangaram; Chakravartya, Manab

    2016-03-04

    Easily reachable electron-poor/rich primary and secondary benzylic phosphates are suitably used as substrates for Friedel-Crafts benzylation reactions with only 1.2 equiv activated/deactivated arenes (no additional solvent) to access structurally and electronically diverse polyarylated alkanes with excellent yields and selectivities at room temperature. Specifically, diversely substituted di/triarylmethanes are generated within 2-30 min using this approach. A wide number of electron-poor polyarylated alkanes are easily accomplished through this route by just tuning the phosphates.

  10. Determination of the active center in calcium-nickel phosphate dehydrogenation catalyst

    SciTech Connect

    Attali, S.; Vigouroux, B.; Lenzi, M.; Pescia, J.

    1980-06-01

    Determination of the active center in calcium-nickel phosphate dehydrogenation catalyst, used industrially in the dehydrogenation of butenes to butadiene, showed that a stable trivalent nickel ion is involved. Apparently, electrons generated in the first (oxidation) step of the reaction are eliminated by reducing the trivalent to divalent nickel which is reoxidized by protons. The results were obtained by propanol dehydration-dehydrogenation on calcium-nickel phosphate (Ca/sub 8/Ni(PO/sub 4//sub )/6) calcined at 400/sup 0/-900/sup 0/C and by ESR spectroscopy.

  11. Combining phosphate and bacteria removal on chemically active filter membranes allows prolonged storage of drinking water.

    PubMed

    Rotzetter, A C C; Kellenberger, C R; Schumacher, C M; Mora, C; Grass, R N; Loepfe, M; Luechinger, N A; Stark, W J

    2013-11-13

    A chemically active filtration membrane with incorporated lanthanum oxide nanoparticles enables the removal of bacteria and phosphate at the same time and thus provides a simple device for preparation of drinking water and subsequent safe storage without using any kind of disinfectants.

  12. Phosphate-Activated Cyclin-Dependent Kinase Stabilizes G1 Cyclin To Trigger Cell Cycle Entry

    PubMed Central

    Menoyo, S.; Ricco, N.; Bru, S.; Hernández-Ortega, S.; Escoté, X.; Aldea, M.

    2013-01-01

    G1 cyclins, in association with a cyclin-dependent kinase (CDK), are universal activators of the transcriptional G1-S machinery during entry into the cell cycle. Regulation of cyclin degradation is crucial for coordinating progression through the cell cycle, but the mechanisms that modulate cyclin stability to control cell cycle entry are still unknown. Here, we show that a lack of phosphate downregulates Cln3 cyclin and leads to G1 arrest in Saccharomyces cerevisiae. The stability of Cln3 protein is diminished in strains with low activity of Pho85, a phosphate-sensing CDK. Cln3 is an in vitro substrate of Pho85, and both proteins interact in vivo. More interestingly, cells that carry a CLN3 allele encoding aspartic acid substitutions at the sites of Pho85 phosphorylation maintain high levels of Cln3 independently of Pho85 activity. Moreover, these cells do not properly arrest in G1 in the absence of phosphate and they die prematurely. Finally, the activity of Pho85 is essential for accumulating Cln3 and for reentering the cell cycle after phosphate refeeding. Taken together, our data indicate that Cln3 is a molecular target of the Pho85 kinase that is required to modulate cell cycle entry in response to environmental changes in nutrient availability. PMID:23339867

  13. Phosphate-activated cyclin-dependent kinase stabilizes G1 cyclin to trigger cell cycle entry.

    PubMed

    Menoyo, S; Ricco, N; Bru, S; Hernández-Ortega, S; Escoté, X; Aldea, M; Clotet, J

    2013-04-01

    G1 cyclins, in association with a cyclin-dependent kinase (CDK), are universal activators of the transcriptional G1-S machinery during entry into the cell cycle. Regulation of cyclin degradation is crucial for coordinating progression through the cell cycle, but the mechanisms that modulate cyclin stability to control cell cycle entry are still unknown. Here, we show that a lack of phosphate downregulates Cln3 cyclin and leads to G1 arrest in Saccharomyces cerevisiae. The stability of Cln3 protein is diminished in strains with low activity of Pho85, a phosphate-sensing CDK. Cln3 is an in vitro substrate of Pho85, and both proteins interact in vivo. More interestingly, cells that carry a CLN3 allele encoding aspartic acid substitutions at the sites of Pho85 phosphorylation maintain high levels of Cln3 independently of Pho85 activity. Moreover, these cells do not properly arrest in G1 in the absence of phosphate and they die prematurely. Finally, the activity of Pho85 is essential for accumulating Cln3 and for reentering the cell cycle after phosphate refeeding. Taken together, our data indicate that Cln3 is a molecular target of the Pho85 kinase that is required to modulate cell cycle entry in response to environmental changes in nutrient availability.

  14. Paraoxonase 1 activity in subchronic low-level inorganic arsenic exposure through drinking water.

    PubMed

    Afolabi, Olusegun K; Wusu, Adedoja D; Ogunrinola, Olufunmilayo O; Abam, Esther O; Babayemi, David O; Dosumu, Oluwatosin A; Onunkwor, Okechukwu B; Balogun, Elizabeth A; Odukoya, Olusegun O; Ademuyiwa, Oladipo

    2016-02-01

    Epidemiological evidences indicate close association between inorganic arsenic exposure via drinking water and cardiovascular diseases. While the exact mechanism of this arsenic-mediated increase in cardiovascular risk factors remains enigmatic, epidemiological studies indicate a role for paraoxonase 1 (PON1) in cardiovascular diseases. To investigate the association between inorganic arsenic exposure and cardiovascular diseases, rats were exposed to sodium arsenite (trivalent; 50, 100, and 150 ppm As) and sodium arsenate (pentavalent; 100, 150, and 200 ppm As) in their drinking water for 12 weeks. PON1 activity towards paraoxon (PONase) and phenylacetate (AREase) in plasma, lipoproteins, hepatic, and brain microsomal fractions were determined. Inhibition of PONase and AREase in plasma and HDL characterized the effects of the two arsenicals. While the trivalent arsenite inhibited PONase by 33% (plasma) and 46% (HDL), respectively, the pentavalent arsenate inhibited the enzyme by 41 and 34%, respectively. AREase activity was inhibited by 52 and 48% by arsenite, whereas the inhibition amounted to 72 and 67%, respectively by arsenate. The pattern of inhibition in plasma and HDL indicates that arsenite induced a dose-dependent inhibition of PONase whereas arsenate induced a dose-dependent inhibition of AREase. In the VLDL + LDL, arsenate inhibited PONase and AREase while arsenite inhibited PONase. In the hepatic and brain microsomal fractions, only the PONase enzyme was inhibited by the two arsenicals. The inhibition was more pronounced in the hepatic microsomes where a 70% inhibition was observed at the highest dose of pentavalent arsenic. Microsomal cholesterol was increased by the two arsenicals resulting in increased cholesterol/phospholipid ratios. Our findings indicate that decreased PON1 activity observed in arsenic exposure may be an incipient biochemical event in the cardiovascular effects of arsenic. Modulation of PON1 activity by arsenic may also be

  15. Norcantharimide analogues possessing terminal phosphate esters and their anti-cancer activity.

    PubMed

    Robertson, Mark J; Gordon, Christopher P; Gilbert, Jayne; McCluskey, Adam; Sakoff, Jennette A

    2011-09-15

    A family of norcantharidin analogues possessing a terminal alcohol (ethanol, propanol, butanol, pentanol, hexanol and cyclohexanol) moiety were treated with either chlorodiethyl, chlorodiphenyl or chloro-bis-trichloroethyl-phosphate to afford highly focused libraries of the corresponding phosphate esters. Subsequent biological screening against a panel of nine human cancer cell lines identified a trend between the ease of phosphate unmasking (phosphate ester hydrolysis) and cell death. The most potent analogues possessed either a diphenyl or a bis-trichloroethyl moiety. The effect of alkyl spacer was also examined with the hexyl analogues typically more potent. 4-Aza-4-(3-{bis(2,2,2-trichloroethyl)phosphate}propyl)-10-oxatricyclo[5.2.1.0]decane-3,5-dione (10b) was the most potent analogue synthesised with an average GI(50) of 11 μM across a panel of nine human carcinoma cell lines: colon carcinoma (HT29 and SW480); breast carcinoma (MCF-7); ovarian carcinoma (A2780); lung carcinoma (H460); skin carcinoma (A431); prostate carcinoma (DU145); neuronal carcinoma (BE2-C) and brain carcinoma (SJ-G2). This represents a fivefold improvement in anti-proliferative activity relative to the lead, norcantharidin. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

  16. [Effects of phosphate fertilizer on active ingredients and antioxidant activities of Chrysanthemum morifolium].

    PubMed

    Liu, Dahui; Liu, Wei; Zhu, Duanwei; Guo, Lanping; Jin, Hang; Zuo, Zhitian; Liu, Li

    2010-09-01

    In order to provide a scientific fertilizer application for the standardized cultivation, the effects of phosphate (P) fertilizer on the active ingredients and antioxidant activities of Chrysanthemum morifolium were studied. Pot experiment was adopted to study the effects of P supply on the yield and the content of flavonoids, chlorogenic acid, soluble sugar, soluble amino acids and crude protein of C. morifolium flower. And effects of P supply on the hydroxyl radical scavenging activity, superoxide anion radical scavenging activity, and 2, 2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radical scavenging activity of flower were researched too. The yield of C. morifolium dry flower increased 129. 94% when P fertilizer was applied. Appropriate application of P fertilizer could also significantly improve the content and accumulation of total flavonoids, chlorogenic acid and soluble sugar in C. morifolium. Thus, the inhibition rates of hydroxyl radical, superoxide anion radical and DPPH free radical of C. morifolium was increased. When the level of P supply exceeded 0.20 g P2O5 per plant, P had also negative influence on the yield and the content of active ingredients and the scavenging activity of hydroxyl radical, superoxide anion radical and DPPH free radical of C. morifolium. Furthermore, there were significant positive correlations between the content of total flavonoids and chlorogenic acid and the inhibition rate of hydroxyl radical, superoxide anion radical and DPPH free radical, respectively. Appropriate application of P fertilizer could be beneficial to the increase the active components and antioxidant activity of C. morifolium. And recommended level of P fertilizer is 0.26-0.28 g x kg(-1).

  17. Investigation into the Mode of Phosphate Activation in the 4-Hydroxy-4-Methyl-2-Oxoglutarate/4-Carboxy-4-Hydroxy-2-Oxoadipate Aldolase from Pseudomonas putida F1

    PubMed Central

    Mazurkewich, Scott; Seah, Stephen Y. K.

    2016-01-01

    The 4-hydroxy-4-methyl-2-oxoglutarate (HMG)/4-carboxy-4-hydroxy-2-oxoadipate (CHA) aldolase is the last enzyme of both the gallate and protocatechuate 4,5-cleavage pathways which links aromatic catabolism to central cellular metabolism. The enzyme is a class II, divalent metal dependent, aldolase which is activated in the presence of inorganic phosphate (Pi), increasing its turnover rate >10-fold. This phosphate activation is unique for a class II aldolase. The aldolase pyruvate methyl proton exchange rate, a probe of the general acid half reaction, was increased 300-fold in the presence of 1 mM Pi and the rate enhancement followed saturation kinetics giving rise to a KM of 397 ± 30 μM. Docking studies revealed a potential Pi binding site close to, or overlapping with, the proposed general acid water site. Putative Pi binding residues were substituted by site-directed mutagenesis which resulted in reductions of Pi activation. Significantly, the active site residue Arg-123, known to be critical for the catalytic mechanism of the enzyme, was also implicated in supporting Pi mediated activation. PMID:27741265

  18. Phosphorus Availability and Release Pattern from Activated Dolomite Phosphate Rock in Central Florida.

    PubMed

    Mao, Xiaoyun; Lu, Qin; Mo, Wei; Xin, Xiaoping; Chen, Xian; He, Zhenli

    2017-06-14

    In this study, novel technology was developed to convert dolomite phosphate rock (DPR) into slow release P fertilizers. The DPR was powdered to <100 mesh and activated with organic molecules under optimal reaction conditions. As compared to original DPR, available P, estimated by water-soluble P released from the three DPRs activated with three types of organic molecules, increased by 6.86, 3.32, and 7.46 times, respectively. Phosphorus supply from the activated DPRs was greater than that of superphosphates (SP). Use of activated DPRs resulted in a significant increase in plant biomass of maize (Zea mays) and millet (Pennisetum glaucum) (succeeding crop), as compared to original DPR, and displayed better effectiveness than monoammonium phosphate or SP. The XRD and FTIR analyses showed that activation did not change the crystal structure of DPR, but the interactions between organic molecules and the P-bearing minerals stimulated P release from DPR.

  19. The glucose-6-phosphate transport is not mediated by a glucose-6-phosphate/phosphate exchange in liver microsomes.

    PubMed

    Marcolongo, Paola; Fulceri, Rosella; Giunti, Roberta; Margittai, Eva; Banhegyi, Gabor; Benedetti, Angelo

    2012-09-21

    A phosphate-linked antiporter activity of the glucose-6-phosphate transporter (G6PT) has been recently described in liposomes including the reconstituded transporter protein. We directly investigated the mechanism of glucose-6-phosphate (G6P) transport in rat liver microsomal vesicles. Pre-loading with inorganic phosphate (Pi) did not stimulate G6P or Pi microsomal inward transport. Pi efflux from pre-loaded microsomes could not be enhanced by G6P or Pi addition. Rapid G6P or Pi influx was registered by light-scattering in microsomes not containing G6P or Pi. The G6PT inhibitor, S3483, blocked G6P transport irrespectively of experimental conditions. We conclude that hepatic G6PT functions as an uniporter.

  20. Archaeal Inorganic Pyrophosphatase Displays Robust Activity under High-Salt Conditions and in Organic Solvents.

    PubMed

    McMillan, Lana J; Hepowit, Nathaniel L; Maupin-Furlow, Julie A

    2015-11-06

    Soluble inorganic pyrophosphatases (PPAs) that hydrolyze inorganic pyrophosphate (PPi) to orthophosphate (Pi) are commonly used to accelerate and detect biosynthetic reactions that generate PPi as a by-product. Current PPAs are inactivated by high salt concentrations and organic solvents, which limits the extent of their use. Here we report a class A type PPA of the haloarchaeon Haloferax volcanii (HvPPA) that is thermostable and displays robust PPi-hydrolyzing activity under conditions of 25% (vol/vol) organic solvent and salt concentrations from 25 mM to 3 M. HvPPA was purified to homogeneity as a homohexamer by a rapid two-step method and was found to display non-Michaelis-Menten kinetics with a Vmax of 465 U · mg(-1) for PPi hydrolysis (optimal at 42°C and pH 8.5) and Hill coefficients that indicated cooperative binding to PPi and Mg(2+). Similarly to other class A type PPAs, HvPPA was inhibited by sodium fluoride; however, hierarchical clustering and three-dimensional (3D) homology modeling revealed HvPPA to be distinct in structure from characterized PPAs. In particular, HvPPA was highly negative in surface charge, which explained its extreme resistance to organic solvents. To demonstrate that HvPPA could drive thermodynamically unfavorable reactions to completion under conditions of reduced water activity, a novel coupled assay was developed; HvPPA hydrolyzed the PPi by-product generated in 2 M NaCl by UbaA (a "salt-loving" noncanonical E1 enzyme that adenylates ubiquitin-like proteins in the presence of ATP). Overall, we demonstrate HvPPA to be useful for hydrolyzing PPi under conditions of reduced water activity that are a hurdle to current PPA-based technologies. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  1. Archaeal Inorganic Pyrophosphatase Displays Robust Activity under High-Salt Conditions and in Organic Solvents

    PubMed Central

    McMillan, Lana J.; Hepowit, Nathaniel L.

    2015-01-01

    Soluble inorganic pyrophosphatases (PPAs) that hydrolyze inorganic pyrophosphate (PPi) to orthophosphate (Pi) are commonly used to accelerate and detect biosynthetic reactions that generate PPi as a by-product. Current PPAs are inactivated by high salt concentrations and organic solvents, which limits the extent of their use. Here we report a class A type PPA of the haloarchaeon Haloferax volcanii (HvPPA) that is thermostable and displays robust PPi-hydrolyzing activity under conditions of 25% (vol/vol) organic solvent and salt concentrations from 25 mM to 3 M. HvPPA was purified to homogeneity as a homohexamer by a rapid two-step method and was found to display non-Michaelis-Menten kinetics with a Vmax of 465 U · mg−1 for PPi hydrolysis (optimal at 42°C and pH 8.5) and Hill coefficients that indicated cooperative binding to PPi and Mg2+. Similarly to other class A type PPAs, HvPPA was inhibited by sodium fluoride; however, hierarchical clustering and three-dimensional (3D) homology modeling revealed HvPPA to be distinct in structure from characterized PPAs. In particular, HvPPA was highly negative in surface charge, which explained its extreme resistance to organic solvents. To demonstrate that HvPPA could drive thermodynamically unfavorable reactions to completion under conditions of reduced water activity, a novel coupled assay was developed; HvPPA hydrolyzed the PPi by-product generated in 2 M NaCl by UbaA (a “salt-loving” noncanonical E1 enzyme that adenylates ubiquitin-like proteins in the presence of ATP). Overall, we demonstrate HvPPA to be useful for hydrolyzing PPi under conditions of reduced water activity that are a hurdle to current PPA-based technologies. PMID:26546423

  2. Phosphate-solubility and phosphatase activity in Gangetic alluvial soil as influenced by organophosphate insecticide residues.

    PubMed

    Majumder, Shyam Prasad; Das, Amal Chandra

    2016-04-01

    An experiment was conducted under laboratory conditions to investigate the effect of four organophosphate insecticides, viz. monocrotophos, profenophos, quinalphos and triazophos at their field application rates (0.75, 1.0, 0.5 and 0.6 kg a.i.ha(-1), respectively), on the growth and activities of phosphate solubilizing microorganisms in relation to availability of insoluble phosphates in the Gangetic alluvial soil of West Bengal, India. The proliferation of phosphate solubilizing microorganisms was highly induced with profenophos (38.3%), while monocrotophos exerted maximum stimulation (20.8%) towards the solubility of insoluble phosphates in soil. The phosphatase activities of the soil (both acid phosphatase and alkaline phosphatase) were significantly increased due to the incorporation of the insecticides in general, and the augmentation was more pronounced with quinalphos (43.1%) followed by profenophos (27.6%) for acid phosphatase, and with monocrotophos (25.2%) followed by profenophos (16.1%) for alkaline phosphatase activity in soil. The total phosphorus was highly retained by triazophos (19.9%) followed by monocrotophos (16.5%), while incorporation of triazophos and quinalphos manifested greater availability of water soluble phosphorus in soil. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Glucose-6-phosphate mediates activation of the carbohydrate responsive binding protein (ChREBP)

    SciTech Connect

    Li, Ming V.; Chen, Weiqin; Harmancey, Romain N.; Nuotio-Antar, Alli M.; Imamura, Minako; Saha, Pradip; Taegtmeyer, Heinrich; Chan, Lawrence

    2010-05-07

    Carbohydrate response element binding protein (ChREBP) is a Mondo family transcription factor that activates a number of glycolytic and lipogenic genes in response to glucose stimulation. We have previously reported that high glucose can activate the transcriptional activity of ChREBP independent of the protein phosphatase 2A (PP2A)-mediated increase in nuclear entry and DNA binding. Here, we found that formation of glucose-6-phosphate (G-6-P) is essential for glucose activation of ChREBP. The glucose response of GAL4-ChREBP is attenuated by D-mannoheptulose, a potent hexokinase inhibitor, as well as over-expression of glucose-6-phosphatase (G6Pase); kinetics of activation of GAL4-ChREBP can be modified by exogenously expressed GCK. Further metabolism of G-6-P through the two major glucose metabolic pathways, glycolysis and pentose-phosphate pathway, is not required for activation of ChREBP; over-expression of glucose-6-phosphate dehydrogenase (G6PD) diminishes, whereas RNAi knockdown of the enzyme enhances, the glucose response of GAL4-ChREBP, respectively. Moreover, the glucose analogue 2-deoxyglucose (2-DG), which is phosphorylated by hexokinase, but not further metabolized, effectively upregulates the transcription activity of ChREBP. In addition, over-expression of phosphofructokinase (PFK) 1 and 2, synergistically diminishes the glucose response of GAL4-ChREBP. These multiple lines of evidence support the conclusion that G-6-P mediates the activation of ChREBP.

  4. Regeneration of spent powdered activated carbon saturated with inorganic ions by cavitation united with ion exchange method.

    PubMed

    Li, Gang; Gao, Hong; Li, Yansheng; Yang, Huixin

    2011-06-01

    Using ion exchange resin as transfer media, regenerate powdered activated carbon (PAC) adsorbed inorganic ions by cavitation to enhance the transfer; we studied how the regeneration time and the mass ratio of resin and PAC influence the regeneration rate respectively through re-adsorption. The result showed that the effective regeneration of PAC saturated with inorganic ions was above 90% using ion exchange resin as media and transfer carrier, the quantity of PAC did not reduced but activated in the process. Copyright © 2011 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  5. A nucleophilic catalysis step is involved in the hydrolysis of aryl phosphate monoesters by human CT acylphosphatase.

    PubMed

    Paoli, Paolo; Pazzagli, Luigia; Giannoni, Elisa; Caselli, Anna; Manao, Giampaolo; Camici, Guido; Ramponi, Giampietro

    2003-01-03

    Acylphosphatase, one of the smallest enzymes, is expressed in all organisms. It displays hydrolytic activity on acyl phosphates, nucleoside di- and triphosphates, aryl phosphate monoesters, and polynucleotides, with acyl phosphates being the most specific substrates in vitro. The mechanism of catalysis for human acylphosphatase (the organ-common type isoenzyme) was investigated using both aryl phosphate monoesters and acyl phosphates as substrates. The enzyme is able to catalyze phosphotransfer from p-nitrophenyl phosphate to glycerol (but not from benzoyl phosphate to glycerol), as well as the inorganic phosphate-H(2)18O oxygen exchange reaction in the absence of carboxylic acids or phenols. In short, our findings point to two different catalytic pathways for aryl phosphate monoesters and acyl phosphates. In particular, in the aryl phosphate monoester hydrolysis pathway, an enzyme-phosphate covalent intermediate is formed, whereas the hydrolysis of acyl phosphates seems a more simple process in which the Michaelis complex is attacked directly by a water molecule generating the reaction products. The formation of an enzyme-phosphate covalent complex is consistent with the experiments of isotope exchange and transphosphorylation from substrates to glycerol, as well as with the measurements of the Brønsted free energy relationships using a panel of aryl phosphates with different structures. His-25 involvement in the formation of the enzyme-phosphate covalent complex during the hydrolysis of aryl phosphate monoesters finds significant confirmation in experiments performed with the H25Q mutated enzyme.

  6. Alkaline Phosphatase Activity : an overlooked player on the phosphate behavior in macrotidal estuaries

    NASA Astrophysics Data System (ADS)

    Delmas, Daniel; Labry, Claire; Youenou, Agnes; Quere, Julien; Auguet, Jean Christophe; Montanie, Helene

    2014-05-01

    The non-conservative behavior of phosphate within the estuarine salinity gradient is essentially assigned to physico-chemical processes, such as desorption at low salinity and to benthic exchanges. Microbial phosphatase activity (APA), generally related to phosphate deficiency, is seldom studied in phosphate rich estuarine waters. In order to address the impact of microbial activity (bacterial abundance, production BSP, APA) on phosphate behavior, we studied these activities on a seasonal basis within the salinity gradient of two macrotidal estuaries presenting different levels of suspended solids. Whatever the season the Charente estuary is characterized by high levels of Suspended Particulate Matter (SPM > 1g.L-1), particularly in the Maximum Turbidity Zone (MTZ) located at the 5-10 psu. In this area characterized by high BSP and APA there is a significant increase of PO4 levels especially during summer. In the Aulne estuary the particle load is significantly lower (1/10) but high BSP and APA are equally recorded. In the highly turbid waters of the Charente estuary, active phytoplankton is virtually absent as pheopigments constitute up to 80% of the total pigments, particularly in the MTZ, therefore APA may essentially have a bacterial origin. In the Aulne estuary attached bacteria are dominant, both in numbers and production, and their distribution along the haline gradient perfectly follows those of APA and phosphate levels. These observations, associated with the very close relationships observed between APA, SPM and BSP, suggest that APA derive mainly from bacterial (attached) origin and operate at the expense of particulate phosphorus and hence contribute to PO4 regeneration, especially in spring and summer. Finally, as APA increased as PO4, whereas the reverse is observed in both fresh and marine waters, an original scheme for APA regulation, related to the large dominance of attached bacteria can be described for the estuarine waters.

  7. Phosphate solubilization characteristics of efficient nitrogen fixing soil Azotobacter strains.

    PubMed

    Nosrati, Rahim; Owlia, Parviz; Saderi, Horieh; Rasooli, Iraj; Ali Malboobi, Mohammad

    2014-08-01

    Azotobacter is a diazotroph bacterium reported to possess various plant growth-promoting characteristics.The aim of this study was to isolate Azotobacter strains capable of fixing nitrogen and effectively hydrolyzing both organic and inorganic Pi compounds. In this study, soil samples collected from a diverse range of slightly alkaline soil types were screened for Azotobacter isolates. The inorganic and organic phosphate solubilization potentials of twenty competent phosphate solubilizing Azotobacter isolates were assessed.Variations were noted in the solubilization potentials. Three isolates, identified as Azotobacter vinelandii strains O2, O4 and O6, were able to fix atmospheric N2 effectively. The nitrogenase activity of these isolates ranged between 158.6 and 326.4 C2H4h(-1)vial(-1) (ethylene). Bacterial growth rates and phosphate solubilization activities were measured quantitatively under various environmental conditions. A close association was evident between phosphate solubilizing ability and growth rate as an indicator of active metabolism. All three phosphate solubilizing bacteria (PSB) were able to withstand temperature as high as 45°C, high concentration of NaCl (upto 5%) and a wide range of initial pH from 5 to 10 while hydrolyzing phosphate compounds actively. Azotobacter vinelandii strains O2, O4 and O6 are superior candidates for biofertilizers that may result in the reduction of chemical nitrogen and phosphate fertilizers leading to increase crop production.

  8. Inorganic polyphosphate is a potent activator of the mitochondrial permeability transition pore in cardiac myocytes

    PubMed Central

    Seidlmayer, Lea K.; Gomez-Garcia, Maria R.; Blatter, Lothar A.; Pavlov, Evgeny

    2012-01-01

    Mitochondrial dysfunction caused by excessive Ca2+ accumulation is a major contributor to cardiac cell and tissue damage during myocardial infarction and ischemia–reperfusion injury (IRI). At the molecular level, mitochondrial dysfunction is induced by Ca2+-dependent opening of the mitochondrial permeability transition pore (mPTP) in the inner mitochondrial membrane, which leads to the dissipation of mitochondrial membrane potential (ΔΨm), disruption of adenosine triphosphate production, and ultimately cell death. Although the role of Ca2+ for induction of mPTP opening is established, the exact molecular mechanism of this process is not understood. The aim of the present study was to test the hypothesis that the adverse effect of mitochondrial Ca2+ accumulation is mediated by its interaction with inorganic polyphosphate (polyP), a polymer of orthophosphates linked by phosphoanhydride bonds. We found that cardiac mitochondria contained significant amounts (280 ± 60 pmol/mg of protein) of short-chain polyP with an average length of 25 orthophosphates. To test the role of polyP for mPTP activity, we investigated kinetics of Ca2+ uptake and release, ΔΨm and Ca2+-induced mPTP opening in polyP-depleted mitochondria. polyP depletion was achieved by mitochondria-targeted expression of a polyP-hydrolyzing enzyme. Depletion of polyP in mitochondria of rabbit ventricular myocytes led to significant inhibition of mPTP opening without affecting mitochondrial Ca2+ concentration by itself. This effect was observed when mitochondrial Ca2+ uptake was stimulated by increasing cytosolic [Ca2+] in permeabilized myocytes mimicking mitochondrial Ca2+ overload observed during IRI. Our findings suggest that inorganic polyP is a previously unrecognized major activator of mPTP. We propose that the adverse effect of polyphosphate might be caused by its ability to form stable complexes with Ca2+ and directly contribute to inner mitochondrial membrane permeabilization. PMID:22547663

  9. Inorganic polyphosphate is a potent activator of the mitochondrial permeability transition pore in cardiac myocytes.

    PubMed

    Seidlmayer, Lea K; Gomez-Garcia, Maria R; Blatter, Lothar A; Pavlov, Evgeny; Dedkova, Elena N

    2012-05-01

    Mitochondrial dysfunction caused by excessive Ca2+ accumulation is a major contributor to cardiac cell and tissue damage during myocardial infarction and ischemia-reperfusion injury (IRI). At the molecular level, mitochondrial dysfunction is induced by Ca2+-dependent opening of the mitochondrial permeability transition pore (mPTP) in the inner mitochondrial membrane, which leads to the dissipation of mitochondrial membrane potential (ΔΨm), disruption of adenosine triphosphate production, and ultimately cell death. Although the role of Ca2+ for induction of mPTP opening is established, the exact molecular mechanism of this process is not understood. The aim of the present study was to test the hypothesis that the adverse effect of mitochondrial Ca2+ accumulation is mediated by its interaction with inorganic polyphosphate (polyP), a polymer of orthophosphates linked by phosphoanhydride bonds. We found that cardiac mitochondria contained significant amounts (280±60 pmol/mg of protein) of short-chain polyP with an average length of 25 orthophosphates. To test the role of polyP for mPTP activity, we investigated kinetics of Ca2+ uptake and release, ΔΨm and Ca2+-induced mPTP opening in polyP-depleted mitochondria. polyP depletion was achieved by mitochondria-targeted expression of a polyP-hydrolyzing enzyme. Depletion of polyP in mitochondria of rabbit ventricular myocytes led to significant inhibition of mPTP opening without affecting mitochondrial Ca2+ concentration by itself. This effect was observed when mitochondrial Ca2+ uptake was stimulated by increasing cytosolic [Ca2+] in permeabilized myocytes mimicking mitochondrial Ca2+ overload observed during IRI. Our findings suggest that inorganic polyP is a previously unrecognized major activator of mPTP. We propose that the adverse effect of polyphosphate might be caused by its ability to form stable complexes with Ca2+ and directly contribute to inner mitochondrial membrane permeabilization.

  10. Properties of Ce-activated alkali-lutetium double phosphate scintillators

    SciTech Connect

    Wiśniewski, D.; Wojtowicz, A. J.; Boatner, Lynn A

    2010-01-01

    The scintillation properties of Ce-activated alkali-lutetium double phosphate single crystals that vary with the alkali ion type and activation level are summarized and compared. The materials investigated here have been identified as fast and efficient scintillators for the detection of x-ray and radiation, and in case of Li3Lu(PO4)2:Ce, for thermal neutron detection as well.

  11. Ordered Mesoporous Cobalt Phosphate with Crystallized Walls toward Highly Active Water Oxidation Electrocatalysts.

    PubMed

    Pramanik, Malay; Li, Cuiling; Imura, Masataka; Malgras, Victor; Kang, Yong-Mook; Yamauchi, Yusuke

    2016-04-06

    A hexagonally ordered mesoporous cobalt phosphate (CoPi) material is prepared by a facile one-pot soft-templating strategy using cetyltrimethylammonium bromide template. Because of its highly accessible surface area and crystalline framework with abundant active sites, the mesoporous CoPi shows a high catalytic activity for the oxygen evolution reaction compared to previously reported noble/transition-metal and nonmetal catalysts. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Glutamic acid-149 is important for enzymatic activity of yeast inorganic pyrophosphatase.

    PubMed

    Gonzalez, M A; Cooperman, B S

    1986-11-04

    Modification of Saccharomyces cerevisiae inorganic pyrophosphatase (PPase) with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide is known to lead to a loss of enzymatic activity, the rate of which is decreased in the presence of ligands binding to the active site [Cooperman, B. S., & Chiu, N. Y. (1973) Biochemistry 12, 1676-1682; Heitman, P., & Uhlig, H. J. (1974) Acta Biol. Med. Ger. 32, 565-594]. In this work we show that, when such inactivation is carried out in the presence of [14C]glycine ethyl ester (GEE), GEE is covalently incorporated into PPase, incorporation into the most highly labeled tryptic peptide is site-specific, as evidenced by the reduction of such incorporation in the presence of the active site ligands Zn2+ and Pi, the extent of formation of this specifically labeled peptide correlates with the fractional loss of PPase activity, and the specifically labeled peptide corresponds to residues 145-153 and the position of incorporation within this peptide is Glu-149. The significance of our findings for the location of the active site and for the catalytic mechanism of PPase is briefly considered in the light of the 3-A X-ray crystallographic structure of Arutyunyun and his colleagues [Arutyunyun, E. G., et al. (1981) Dokl. Akad. Nauk SSSR 258, 1481-1485; Kuranova, I. P., et al. (1983) Bioorg. Khim. 9, 1611-1919; Terzyan, S. S., et al. (1984) Bioorg. Khim. 10, 1469-1482].

  13. Determination of phosphate in natural waters by activation analysis of tungstophosphoric acid

    USGS Publications Warehouse

    Allen, Herbert E.; Hahn, Richard B.

    1969-01-01

    Activation analysis may be used to determine quantitatively traces of phosphate in natural waters. Methods based on the reaction 31P(n,γ)32P are subject to interference by sulfur and chlorine which give rise to 32P through n,p and n,α reactions. If the ratio of phosphorus to sulfur or chlorine is small, as it is in most natural waters, accurate analyses by these methods are difficult to achieve. In the activation analysis method, molybdate and tungstate ions are added to samples containing phosphate ion to form tungstomolybdophosphoric acid. The complex is extracted with 2,6-dimethyl-4-heptanone. After activation of an aliquot of the organic phase for 1 hour at a flux of 1013 neutrons per cm2, per second, the gamma spectrum is essentially that of tungsten-187. The induced activity is proportional to the concentration of phosphate in the sample. A test of the method showed it to give accurate results at concentrations of 4 to at least 200 p.p.b. of phosphorus when an aliquot of 100 μl. was activated. By suitable reagent purification, counting for longer times, and activation of larger aliquots, the detection limit could be lowered several hundredfold.

  14. Inhibition of anaerobic phosphate release by nitric oxide in activated sludge.

    PubMed

    Van Niel, E W; Appeldoorn, K J; Zehnder, A J; Kortstee, G J

    1998-08-01

    Activated sludge not containing significant numbers of denitrifying, polyphosphate [poly(P)]-accumulating bacteria was grown in a fill-and-draw system and exposed to alternating anaerobic and aerobic periods. During the aerobic period, poly(P) accumulated up to 100 mg of P x g of (dry) weight. When portions of the sludge were incubated anaerobically in the presence of acetate, 80 to 90% of the intracellular poly(P) was degraded and released as orthophosphate. Degradation of poly(P) was mainly catalyzed by the concerted action of polyphosphate:AMP phosphotransferase and adenylate kinase, resulting in ATP formation. In the presence of 0.3 mM nitric oxide (NO) in the liquid-phase release of phosphate, uptake of acetate, formation of poly-beta-hydroxybutyrate, utilization of glycogen, and formation of ATP were severely inhibited or completely abolished. In cell extracts of the sludge, adenylate kinase activity was completely inhibited by 0.15 mM NO. The nature of this inhibition was probably noncompetitive, similar to that with hog adenylate kinase. Activated sludge polyphosphate glucokinase was also completely inhibited by 0.15 mM NO. It is concluded that the inhibitory effect of NO on acetate-mediated phosphate release by the sludge used in this study is due to the inhibition of adenylate kinase in the phosphate-releasing organisms. The inhibitory effect of nitrate and nitrite on phosphate release is probably due to their conversion to NO. The lack of any inhibitory effect of NO on adenylate kinase of the poly(P)-accumulating Acinetobacter johnsonii 210A suggests that this type of organism is not involved in the enhanced biological phosphate removal by the sludges used.

  15. Genetic expression of hexokinase and glucose phosphate isomerase in late-stage mouse preimplantation embryos: transcription activities in glucose/phosphate-containing HTF and glucose/phosphate-free P1 media.

    PubMed

    Johnson, M D; Batey, D W; Behr, B; Barro, J

    1997-04-01

    In mouse and human preimplantation development, pyruvate is consumed preferentially during early embryogenesis; however, during the morula and blastocyst stages, glucose is the preferred energy substrate. Studies have suggested that the glycolytic enzymes, hexokinase and glucose phosphate isomerase, are important enzymes in glucose metabolism during these later stages of human and mouse preimplantation development. In order to investigate the genetic activities of these enzymes in late-stage mouse embryos developing in vitro, we analysed hexokinase and glucose phosphate isomerase transcription activities by qualitative RNA assays using reverse transcriptase-nested polymerase chain reaction amplification of individual mouse morulae and early blastocysts incubated in glucose/phosphate-free preimplantation stage one (P1) medium and glucose/phosphate-containing human tubal fluid (HTF) medium. We observed an increased incidence of hexokinase transcripts in the population of blastocysts compared with morulae, and differences in transcript incidence between early blastocysts developing in HTF medium and in P1 medium. In contrast, glucose phosphate isomerase transcripts were consistantly present in all embryos analysed, and appear to be constitutively expressed during late-stage mouse embryogenesis. The different activity patterns of the two glycolytic genes may reflect different mechanisms of gene regulation or differential transcript stability during the later stages of mouse preimplantation development.

  16. Tuning laccase catalytic activity with phosphate functionalized carbon dots by visible light.

    PubMed

    Li, Hao; Guo, Sijie; Li, Chuanxi; Huang, Hui; Liu, Yang; Kang, Zhenhui

    2015-05-13

    The phosphate functionalized carbon dots (PCDs) with high biocompatibility and low toxicity can be used as efficient additives for the construction of laccase/PCDs hybrids catalyst. A series of experiments indicated that the activity of laccase/PCDs was higher than that of free laccase (increased by 47.7%). When laccase/PCDs hybrids catalyst was irradiated with visible light (laccase/PCDs-Light), its activity was higher than that of laccase/PCDs hybrids without light irradiation (increased by 92.1%). In the present system, the T1 Cu in laccase was combined with the phosphate group on PCDs, which can increase binding capacity of laccase/PCDs hybrids and substrate. Further, the visible light irradiation increased the donating and accepting electronic capability of the laccase/PCDs hybrids, improving their catalytic activity.

  17. Self-assembled organic-inorganic hybrid glucoamylase nanoflowers with enhanced activity and stability.

    PubMed

    Nadar, Shamraja S; Gawas, Sarita D; Rathod, Virendra K

    2016-11-01

    An organic-inorganic hybrid glucoamylase nanoflower was prepared in single pot by simple, facile and highly efficient method. The stepwise formation of enzyme-embedded hybrid nanoflowers and influence of experimental parameters viz. pH of solution mixture, enzyme and copper ion concentration on the activity of prepared hybrid nanoflowers were systematically investigated. The self-assembled hybrid glucoamylase nanoflowers were synthesized by mixing aqueous solution of copper sulphate (200mM) with PBS (pH 7.5, 5mM) containing glucoamylase (1mg/mL) in 24h at room temperature. These prepared nanoflowers were further characterized by FT-IR, SEM and XRD. The hybrid nanoflowers exhibited 204% enhanced activity recovery and two folds improvement in thermal stability in terms of half-life (in the range of 50-70°C) with respect to the free form. The hybrid glucoamylase nanoflowers retained 70% residual activity after eight successive cycles indicating their excellent durability. Additionally, the nanoflowers retained up to 91% residual activity upto 25 days of storage. Moreover, the conformational changes occurred in glucoamylase structure after preparing hybrid nanoflowers were evaluated by FT-IR spectroscopy data tools.

  18. Increased recovery rates of phosphocreatine and inorganic phosphate after isometric contraction in oxidative muscle fibers and elevated hepatic insulin resistance in homozygous carriers of the A-allele of FTO rs9939609.

    PubMed

    Grunnet, Louise G; Brøns, Charlotte; Jacobsen, Stine; Nilsson, Emma; Astrup, Arne; Hansen, Torben; Pedersen, Oluf; Poulsen, Pernille; Quistorff, Bjørn; Vaag, Allan

    2009-02-01

    Recent studies identified the rs9939609 A-allele of the FTO (fat mass and obesity associated) gene as being associated with obesity and type 2 diabetes. We studied the role of the A-allele in the regulation of peripheral organ functions involved in the pathogenesis of obesity and type 2 diabetes. Forty-six young men underwent a hyperinsulinemic euglycemic clamp with excision of skeletal muscle biopsies, an iv glucose tolerance test, 31phosphorous magnetic resonance spectroscopy, and 24-h whole body metabolism was measured in a respiratory chamber. The FTO rs9939609 A-allele was associated with elevated fasting blood glucose and plasma insulin, hepatic insulin resistance, and shorter recovery half-times of phosphocreatine and inorganic phosphate after exercise in a primarily type I muscle. These relationships--except for fasting insulin--remained significant after correction for body fat percentage. The risk allele was not associated with fat distribution, peripheral insulin sensitivity, insulin secretion, 24-h energy expenditure, or glucose and fat oxidation. The FTO genotype did not influence the mRNA expression of FTO or a set of key nuclear or mitochondrially encoded genes in skeletal muscle during rest. Increased energy efficiency--and potentially increased mitochondrial coupling--as suggested by faster recovery rates of phosphocreatine and inorganic phosphate in oxidative muscle fibers may contribute to the increased risk of obesity and type 2 diabetes in homozygous carriers of the FTO A-risk allele. Hepatic insulin resistance may represent the key metabolic defect responsible for mild elevations of fasting blood glucose associated with the FTO phenotype.

  19. Effect of lysine to alanine mutations on the phosphate activation and BPTES inhibition of glutaminase.

    PubMed

    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.

  20. Carbonic anhydrase inhibitors. Interaction of isozymes I, II, IV, V, and IX with phosphates, carbamoyl phosphate, and the phosphonate antiviral drug foscarnet.

    PubMed

    Rusconi, Stefano; Innocenti, Alessio; Vullo, Daniela; Mastrolorenzo, Antonio; Scozzafava, Andrea; Supuran, Claudiu T

    2004-12-06

    A detailed inhibition study of five carbonic anhydrase (CA, EC 4.2.1.1) isozymes with inorganic phosphates, carbamoyl phosphate, the antiviral phosphonate foscarnet as well as formate is reported. The cytosolic isozyme hCA I was weakly inhibited by neutral phosphate, strongly inhibited by carbamoyl phosphate (K(I) of 9.4 microM), and activated by hydrogen- and dihydrogenphosphate, foscarnet and formate (best activator foscarnet, K(A)=12 microM). The cytosolic isozyme hCA II was weakly inhibited by all the investigated anions, with carbamoyl phosphate showing a K(I) of 0.31 mM. The membrane-associated isozyme hCA IV was the most sensitive to inhibition by phosphates/phosphonates, showing a K(I) of 84 nM for PO(4)(3-), of 9.8 microM for HPO(4)(2-), and of 9.9 microM for carbamoyl phosphate. Foscarnet was the best inhibitor of this isozyme (K(I) of 0.82 mM) highly abundant in the kidneys, which may explain some of the renal side effects of the drug. The mitochondrial isozyme hCA V was weakly inhibited by all phosphates/phosphonates, except carbamoyl phosphate, which showed a K(I) of 8.5 microM. Thus, CA V cannot be the isozyme involved in the carbamoyl phosphate synthetase I biosynthetic reaction, as hypothesized earlier. Furthermore, the relative resistance of CA V to inhibition by inorganic phosphates suggests an evolutionary adaptation of this mitochondrial isozyme to the presence of high concentrations of such anions in these energy-converting organelles, where high amounts of ATP are produced by ATP synthetase, from ADP and inorganic phosphates. The transmembrane, tumor-associated isozyme hCA IX was on the other hand slightly inhibited by all these anions.

  1. Microbial activities and phosphorus cycling: An application of oxygen isotope ratios in phosphate

    NASA Astrophysics Data System (ADS)

    Stout, Lisa M.; Joshi, Sunendra R.; Kana, Todd M.; Jaisi, Deb P.

    2014-08-01

    Microorganisms carry out biochemical transformations of nutrients that make up their cells. Therefore, understanding how these nutrients are transformed or cycled in natural environments requires knowledge of microbial activity. Commonly used indicators for microbial activity typically include determining microbial respiration by O2/CO2 measurements, cell counts, and measurement of enzyme activities. However, coupled studies on nutrient cycling and microbial activity are not given enough emphasis. Here we apply phosphate oxygen isotope ratios (δ18OP) as a tool for measurement of microbial activity and compare the rate of isotope exchange with methods of measuring microbial activities that are more commonly applied in environmental studies including respiration, dehydrogenase activity, alkaline phosphatase activity, and cell counts. Our results show that different bacteria may have different strategies for P uptake, storage and release, their respiration and consequently expression of DHA and APase activities, but in general the trend of their enzyme activities are comparable. Phosphate δ18OP values correlated well with these other parameters used to measure microbial activity with the strongest linear relationships between δ18OP and CO2 evolution (r = -0.99). Even though the rate of isotope exchange for each microorganism used in this study is different, the rate per unit CO2 respiration showed one general trend, where δ18OP values move towards equilibrium while CO2 is generated. While this suggests that P cycling among microorganisms used in this study can be generalized, further research is needed to determine whether the microorganism-specific isotope exchange trend may occur in natural environments. In summary, phosphate oxygen isotope measurements may offer an alternative for use as a tracer to measure microbial activity in soils, sediments, and many other natural environments.

  2. A potent synthetic inorganic antibiotic with activity against drug-resistant pathogens

    PubMed Central

    Hubick, Shelby; Jayaraman, Arumugam; McKeen, Alexander; Reid, Shelby; Alcorn, Jane; Stavrinides, John; Sterenberg, Brian T.

    2017-01-01

    The acronymously named “ESKAPE” pathogens represent a group of bacteria that continue to pose a serious threat to human health, not only due to their propensity for repeated emergence, but also due to their ability to “eskape” antibiotic treatment12. The evolution of multi-drug resistance in these pathogens alone has greatly outpaced the development of new therapeutics, necessitating an alternative strategy for antibiotic development that considers the evolutionary mechanisms driving antibiotic resistance. In this study, we synthesize a novel inorganic antibiotic, phosphopyricin, which has antibiotic activity against the Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). We show that this potent antibiotic is bactericidal, and exhibits low toxicity in an acute dose assay in mice. As a synthetic compound that does not occur naturally, phosphopyricin would be evolutionarily foreign to microbes, thereby slowing the evolution of resistance. In addition, it loses antibiotic activity upon exposure to light, meaning that the active antibiotic will not accumulate in the general environment where strong selective pressures imposed by antibiotic residuals are known to accelerate resistance. Phosphopyricin represents an innovation in antimicrobials, having a synthetic core, and a photosensitive chemical architecture that would reduce accumulation in the environment. PMID:28165020

  3. A potent synthetic inorganic antibiotic with activity against drug-resistant pathogens.

    PubMed

    Hubick, Shelby; Jayaraman, Arumugam; McKeen, Alexander; Reid, Shelby; Alcorn, Jane; Stavrinides, John; Sterenberg, Brian T

    2017-02-06

    The acronymously named "ESKAPE" pathogens represent a group of bacteria that continue to pose a serious threat to human health, not only due to their propensity for repeated emergence, but also due to their ability to "eskape" antibiotic treatment. The evolution of multi-drug resistance in these pathogens alone has greatly outpaced the development of new therapeutics, necessitating an alternative strategy for antibiotic development that considers the evolutionary mechanisms driving antibiotic resistance. In this study, we synthesize a novel inorganic antibiotic, phosphopyricin, which has antibiotic activity against the Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). We show that this potent antibiotic is bactericidal, and exhibits low toxicity in an acute dose assay in mice. As a synthetic compound that does not occur naturally, phosphopyricin would be evolutionarily foreign to microbes, thereby slowing the evolution of resistance. In addition, it loses antibiotic activity upon exposure to light, meaning that the active antibiotic will not accumulate in the general environment where strong selective pressures imposed by antibiotic residuals are known to accelerate resistance. Phosphopyricin represents an innovation in antimicrobials, having a synthetic core, and a photosensitive chemical architecture that would reduce accumulation in the environment.

  4. Mn0.95I0.02[PO3(OH)] · 2H2O phosphate-iodate, an inorganic analogue of phosphonates

    NASA Astrophysics Data System (ADS)

    Belokoneva, E. L.; Dimitrova, O. V.; Volkov, A. S.

    2015-09-01

    The new Mn0.95I0.02[PO3(OH)] · 2H2O phosphate-iodate (space group Pnam = Pnma, D {2/h 16}) is obtained under hydrothermal conditions. The crystal structure is determined without preliminary knowledge of the chemical formula. The structure consists of layers of MnО6 octahedra connected with PO4 tetrahedra. Water molecules are located between the layers. [IO3]- groups having a typical umbrella-like coordination are statistically implanted in layers of MnО6 octahedra at a distance of 1.2 Å from Mn atoms. Their content in the crystal is minor. The structures of the phosphate-iodate coincides with the structures of phosphonates with consideration for the replacement of one (OH) vertex of the РО4 tetrahedron by the organic methyl radical СН3. In the structures of phosphonates and earlier studied phosphates, identical layers are distinguished and the cause of the existence of two MDO varieties is established based on the analysis within the OD theory. Possible hybrid structures derived from the prototypes under consideration are predicted.

  5. Impact of phosphate concentration on docosahexaenoic acid production and related enzyme activities in fermentation of Schizochytrium sp.

    PubMed

    Ren, Lu-Jing; Feng, Yun; Li, Juan; Qu, Liang; Huang, He

    2013-09-01

    Docosahexaenoic acid (DHA) is an important and widely used infant food additive. In this study, the effects of phosphate concentration on lipid and especially DHA synthesis in the oleaginous fungi Schizochytrium sp. HX-308 have been investigated in batch cultures. The maximum DHA yield (8.9 g/L) and DHA productivity (148.3 mg/L h) in 0.1 g/L KH2PO4 concentration were higher than the DHA yield (6.2 g/L) and DHA productivity (86.1 mg/L h) in 4 g/L KH2PO4 concentration. Furthermore, differences in related enzyme activities (malic enzyme, glucose-6-phosphate dehydrogenase and NAD(+)-isocitrate dehydrogenase) between phosphate-sufficient and phosphate-limitation conditions were assayed. The results showed that the phosphate-limitation condition could maintain higher activities of malic enzyme and glucose-6-phosphate dehydrogenase in addition to lower activity of NAD(+)-isocitrate dehydrogenase. In addition, glucose-6-phosphate dehydrogenase might be the main supplier of NADPH at the early stage of fermentation while malic enzyme might be the provider at the late stage. This information might explain the regulation mechanism of phosphate limitation for lipid production and be useful for further DHA production enhancement.

  6. Activating the phosphate nucleophile at the catalytic site of purine nucleoside phosphorylase: a vibrational spectroscopic study.

    PubMed

    Deng, Hua; Lewandowicz, Andrzej; Schramm, Vern L; Callender, Robert

    2004-08-11

    Difference Raman and FTIR studies complemented by vibrational analysis based on ab initio calculations show that the dianionic phosphate in the PNP.ImmH.PO4 complex is forced into a unique bonding arrangement in which one of the PO bonds is greatly polarized by enzyme active site interactions, such that it resembles a PO bond that is about one-quarter of the way toward forming a bridging P-O-C single P-O bond.

  7. Mapping calcium phosphate activated gene networks as a strategy for targeted osteoinduction of human progenitors.

    PubMed

    Eyckmans, Jeroen; Roberts, Scott J; Bolander, Johanna; Schrooten, Jan; Chen, Christopher S; Luyten, Frank P

    2013-06-01

    Although calcium phosphate-containing biomaterials are promising scaffolds for bone regenerative strategies, the osteoinductive capacity of such materials is poorly understood. In this study, we investigated whether endogenous mechanisms of in vivo calcium phosphate-driven, ectopic bone formation could be identified and used to induce enhanced differentiation in vitro of the same progenitor population. To accomplish this, human periosteum derived cells (hPDCs) were seeded on hydroxyapatite/collagen scaffolds (calcium phosphate rich matrix or CPRM), or on decalcified scaffolds (calcium phosphate depleted matrix or CPDM), followed by subcutaneous implantation in nude mice to trigger ectopic bone formation. In this system, osteoblast differentiation occurred in CPRM scaffolds, but not in CPDM scaffolds. Gene expression was assessed by human full-genome microarray at 20 h after seeding, and 2, 8 and 18 days after implantation. In both matrices, implantation of the cell constructs triggered a similar gene expression cascade, however, gene expression dynamics progressed faster in CPRM scaffolds than in CPDM scaffolds. The difference in gene expression dynamics was associated with differential activation of hub genes and molecular signaling pathways related to calcium signaling (CREB), inflammation (TNFα, NFkB, and IL6) and bone development (TGFβ, β-catenin, BMP, EGF, and ERK signaling). Starting from this set of pathways, a growth factor cocktail was developed that robustly enhanced osteogenesis in vitro and in vivo. Taken together, our data demonstrate that through the identification and subsequent stimulation of genes, proteins and signaling pathways associated with calcium phosphate mediated osteoinduction, a focused approach to develop targeted differentiation protocols in adult progenitor cells can be achieved. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Photoluminescence Mechanism and Photocatalytic Activity of Organic-Inorganic Hybrid Materials Formed by Sequential Vapor Infiltration.

    PubMed

    Akyildiz, Halil I; Stano, Kelly L; Roberts, Adam T; Everitt, Henry O; Jur, Jesse S

    2016-05-03

    Organic-inorganic hybrid materials formed by sequential vapor infiltration (SVI) of trimethylaluminum into polyester fibers are demonstrated, and the photoluminescence of the fibers is evaluated using a combined UV-vis and photoluminescence excitation (PLE) spectroscopy approach. The optical activity of the modified fibers depends on infiltration thermal processing conditions and is attributed to the reaction mechanisms taking place at different temperatures. At low temperatures a single excitation band and dual emission bands are observed, while, at high temperatures, two distinct absorption bands and one emission band are observed, suggesting that the physical and chemical structure of the resulting hybrid material depends on the SVI temperature. Along with enhancing the photoluminescence intensity of the PET fibers, the internal quantum efficiency also increased to 5-fold from ∼4-5% to ∼24%. SVI processing also improved the photocatalytic activity of the fibers, as demonstrated by photodeposition of Ag and Au metal particles out of an aqueous metal salt solution onto fiber surfaces via UVA light exposure. Toward applications in flexible electronics, well-defined patterning of the metallic materials is achieved by using light masking and focused laser rastering approaches.

  9. Enhancing the adsorption of ionic liquids onto activated carbon by the addition of inorganic salts.

    PubMed

    Neves, Catarina M S S; Lemus, Jesús; Freire, Mara G; Palomar, Jose; Coutinho, João A P

    2014-09-15

    Most ionic liquids (ILs) are either water soluble or present a non-negligible miscibility with water that may cause some harmful effects upon their release into the environment. Among other methods, adsorption of ILs onto activated carbon (AC) has shown to be an effective technique to remove these compounds from aqueous solutions. However, this method has proved to be viable only for hydrophobic ILs rather than for the hydrophilic that, being water soluble, have a larger tendency for contamination. In this context, an alternative approach using the salting-out ability of inorganic salts is here proposed to enhance the adsorption of hydrophilic ILs onto activated carbon. The effect of the concentrations of Na2SO4 on the adsorption of five ILs onto AC was investigated. A wide range of ILs that allow the inspection of the IL cation family (imidazolium- and pyridinium-based) and the anion nature (accounting for its hydrophilicity and fluorination) through the adsorption onto AC was studied. In general, it is shown that the use of Na2SO4 enhances the adsorption of ILs onto AC. In particular, this effect is highly relevant when dealing with hydrophilic ILs that are those that are actually poorly removed by AC. In addition, the COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used aiming at complementing the experimental data obtained. This work contributes with the development of novel methods to remove ILs from water streams aiming at creating "greener" processes.

  10. Activation and splitting of carbon dioxide on the surface of an inorganic electride material.

    PubMed

    Toda, Yoshitake; Hirayama, Hiroyuki; Kuganathan, Navaratnarajah; Torrisi, Antonio; Sushko, Peter V; Hosono, Hideo

    2013-01-01

    Activation of carbon dioxide is the most important step in its conversion into valuable chemicals. Surfaces of stable oxide with a low work function may be promising for this purpose. Here we report that the surfaces of the inorganic electride [Ca24Al28O64](4+)(e(-))4 activate and split carbon dioxide at room temperature. This behaviour is attributed to a high concentration of localized electrons in the near-surface region and a corrugation of the surface that can trap oxygen atoms and strained carbon monoxide and carbon dioxide molecules. The [Ca24Al28O64](4+)(e(-))4 surface exposed to carbon dioxide is studied using temperature-programmed desorption, and spectroscopic methods. The results of these measurements, corroborated with ab initio simulations, show that both carbon monoxide and carbon dioxide adsorb on the [Ca24Al28O64](4+)(e(-))4 surface at RT and above and adopt unusual configurations that result in desorption of molecular carbon monoxide and atomic oxygen upon heating.

  11. Activation and splitting of carbon dioxide on the surface of an inorganic electride material

    PubMed Central

    Toda, Yoshitake; Hirayama, Hiroyuki; Kuganathan, Navaratnarajah; Torrisi, Antonio; Sushko, Peter V.; Hosono, Hideo

    2013-01-01

    Activation of carbon dioxide is the most important step in its conversion into valuable chemicals. Surfaces of stable oxide with a low work function may be promising for this purpose. Here we report that the surfaces of the inorganic electride [Ca24Al28O64]4+(e−)4 activate and split carbon dioxide at room temperature. This behaviour is attributed to a high concentration of localized electrons in the near-surface region and a corrugation of the surface that can trap oxygen atoms and strained carbon monoxide and carbon dioxide molecules. The [Ca24Al28O64]4+(e−)4 surface exposed to carbon dioxide is studied using temperature-programmed desorption, and spectroscopic methods. The results of these measurements, corroborated with ab initio simulations, show that both carbon monoxide and carbon dioxide adsorb on the [Ca24Al28O64]4+(e−)4 surface at RT and above and adopt unusual configurations that result in desorption of molecular carbon monoxide and atomic oxygen upon heating. PMID:23986101

  12. Enhancing the adsorption of ionic liquids onto activated carbon by the addition of inorganic salts

    PubMed Central

    Neves, Catarina M. S. S.; Lemus, Jesús; Freire, Mara G.; Palomar, Jose; Coutinho, João A. P.

    2014-01-01

    Most ionic liquids (ILs) are either water soluble or present a non-negligible miscibility with water that may cause some harmful effects upon their release into the environment. Among other methods, adsorption of ILs onto activated carbon (AC) has shown to be an effective technique to remove these compounds from aqueous solutions. However, this method has proved to be viable only for hydrophobic ILs rather than for the hydrophilic that, being water soluble, have a larger tendency for contamination. In this context, an alternative approach using the salting-out ability of inorganic salts is here proposed to enhance the adsorption of hydrophilic ILs onto activated carbon. The effect of the concentrations of Na2SO4 on the adsorption of five ILs onto AC was investigated. A wide range of ILs that allow the inspection of the IL cation family (imidazolium- and pyridinium-based) and the anion nature (accounting for its hydrophilicity and fluorination) through the adsorption onto AC was studied. In general, it is shown that the use of Na2SO4 enhances the adsorption of ILs onto AC. In particular, this effect is highly relevant when dealing with hydrophilic ILs that are those that are actually poorly removed by AC. In addition, the COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used aiming at complementing the experimental data obtained. This work contributes with the development of novel methods to remove ILs from water streams aiming at creating “greener” processes. PMID:25516713

  13. Cardiac preconditioning with sphingosine-1-phosphate requires activation of signal transducer and activator of transcription-3

    PubMed Central

    Kelly-Laubscher, Roisin F; King, Jonathan C; Hacking, Damian; Somers, Sarin; Hastie, Samantha; Stewart, Tessa; Imamdin, Aqeela; Maarman, Gerald; Pedretti, Sarah; Lecour, Sandrine

    2014-01-01

    Summary Aims Sphingosine-1-phosphate (S1P) is a cardioprotective agent. Signal transducer and activator of transcription 3 (STAT-3) is a key mediator of many cardioprotective agents. We aimed to explore whether STAT-3 is a key mediator in S1P-induced preconditioning. Methods Langendorff-perfused hearts from Wistar rats and wild-type or cardiomyocyte-specific STAT-3 knockout mice were pre-treated with S1P (10 nmol/l), with or without the STAT-3 pathway inhibitor AG490, before an ischaemia–reperfusion insult. Triphenyltetrazolium chloride and Evans blue staining were used for the determination of infarct size. Western blot analysis was carried out on the S1P pre-treated hearts for detection of cytosolic, nuclear and mitochondrial phosphorylated and total STAT-3 proteins. Results Pre-treatment with S1P decreased the infarct size in isolated rat (5 ± 3% vs control 26 ± 8%, p < 0.01) and wild-type mouse hearts (13 ± 1% vs control 33 ± 3%, p < 0.05). This protective effect was abolished in the rat hearts pre-treated with AG490 (30 ± 10%, p = ns vs control) and in the hearts from STAT-3 knockout mice (35 ± 4% vs control 30 ± 3%, p = ns). Levels of phosphorylated STAT-3 were significantly increased in both the nuclear (p < 0.05 vs control) and mitochondrial (p < 0.05 vs control) fractions in the S1P pre-treated hearts, but remained unchanged in the cytosolic fraction (p = ns vs control). Conclusion These novel results demonstrate that pharmacological preconditioning with S1P in the isolated heart is mediated by activation of mitochondrial and nuclear STAT-3, therefore suggesting that S1P may be a novel therapeutic target to modulate mitochondrial and nuclear function in cardiovascular disease in order to protect the heart against ischaemia–reperfusion. PMID:25000441

  14. Inorganic scintillation detectors based on Eu-activated phosphors for 192Ir brachytherapy

    NASA Astrophysics Data System (ADS)

    Kertzscher, Gustavo; Beddar, Sam

    2017-06-01

    The availability of real-time treatment verification during high-dose-rate (HDR) brachytherapy is currently limited. Therefore, we studied the luminescence properties of the widely commercially available scintillators using the inorganic materials Eu-activated phosphors Y2O3:Eu, YVO4:Eu, Y2O2S:Eu, and Gd2O2S:Eu to determine whether they could be used to accurately and precisely verify HDR brachytherapy doses in real time. The suitability for HDR brachytherapy of inorganic scintillation detectors (ISDs) based on the 4 Eu-activated phosphors in powder form was determined based on experiments with a 192Ir HDR brachytherapy source. The scintillation intensities of the phosphors were 16-134 times greater than that of the commonly used organic plastic scintillator BCF-12. High signal intensities were achieved with an optimized packing density of the phosphor mixture and with a shortened fiber-optic cable. The influence of contaminating Cerenkov and fluorescence light induced in the fiber-optic cable (stem signal) was adequately suppressed by inserting between the fiber-optic cable and the photodetector a 25 nm band-pass filter centered at the emission peak. The spurious photoluminescence signal induced by the stem signal was suppressed by placing a long-pass filter between the scintillation detector volume and the fiber-optic cable. The time-dependent luminescence properties of the phosphors were quantified by measuring the non-constant scintillation during irradiation and the afterglow after the brachytherapy source had retracted. We demonstrated that a mixture of Y2O3:Eu and YVO4:Eu suppressed the time-dependence of the ISDs and that the time-dependence of Y2O2S:Eu and Gd2O2S:Eu introduced large measurement inaccuracies. We conclude that ISDs based on a mixture of Y2O3:Eu and YVO4:Eu are promising candidates for accurate and precise real-time verification technology for HDR BT that is cost effective and straightforward to manufacture. Widespread dissemination of this

  15. [Osteogenic activity of porous calcium phosphate ceramics fabricated by rapid prototyping].

    PubMed

    He, Chenguang; Zhao, Li; Lin, Liulan; Gu, Huijie; Zhou, Heng; Cui, Lei

    2010-07-01

    Calcium phosphate bioceramics has a broad application prospect because of good biocompatibility, but porous scaffolds with complex shape can not be prepared by the traditional methods. To fabricate porous calcium phosphate ceramics by rapid prototyping and to investigate the in vitro osteogenic activities. The porous calcium phosphate ceramics was fabricated by rapid prototyping. The bone marrow mesenchymal stem cells (BMSCs) were isolated from bone marrow of Beagle canine, and the 3rd passage BMSCs were seeded onto the porous ceramics. The cell/ceramics composite cultured in osteogenic medium were taken as the experimental group (group A) and the cell/ceramics composite cultured in growth medium were taken as the control group (group B). Meanwhile, the cells seeded on the culture plate were cultured in osteogenic medium or growth medium respectively as positive control (group C) or negative control (group D). After 1, 3, and 7 days of culture, the cell proliferation and osteogenic differentiation on the porous ceramics were evaluated by DNA quantitative analysis, histochemical staining and alkaline phosphatase (ALP) activity. After DiO fluorescent dye, the cell adhesion, growth, and proliferation on the porous ceramics were also observed by confocal laser scanning microscope (CLSM). DNA quantitative analysis results showed that the number of BMSCs in all groups increased continuously with time. Plateau phase was not obvious in groups A and B, but it was clearly observed in groups C and D. The CLSM observation indicated that the activity of BMSCs was good and the cells spread extensively, showing good adhesion and proliferation on the porous calcium phosphate ceramics prepared by rapid prototyping. ALP quantitative analysis results showed that the stain of cells on the ceramics became deeper and deeper with time in groups A and B, the staining degree in group A were stronger than that in group B. There was no significant difference in the change of the ALP activity

  16. Continuous cellularization of calcium phosphate hybrid scaffolds induced by plasma polymer activation.

    PubMed

    Bergemann, Claudia; Cornelsen, Matthias; Quade, Antje; Laube, Thorsten; Schnabelrauch, Matthias; Rebl, Henrike; Weißmann, Volker; Seitz, Hermann; Nebe, Barbara

    2016-02-01

    The generation of hybrid materials based on β-tricalcium phosphate (TCP) and various biodegradable polymers like poly(l-lactide-co-d,l-lactide) (PLA) represents a common approach to overcoming the disadvantages of pure TCP devices. These disadvantages lie in TCP's mechanical properties, such as brittleness. The positive characteristic of PLA - improvement of compressive strength of calcium phosphate scaffolds - is diametrically opposed to its cell attractiveness. Therefore, the objective of this work was to optimize osteoblast migration and cellularization inside a three-dimensionally (3D) printed, PLA polymer stabilized TCP hybrid scaffold by a plasma polymer process depositing amino groups via allylamine. MG-63 osteoblastic cells inside the 10mm hybrid scaffold were dynamically cultivated for 14days in a 3D model system integrated in a perfusion reactor. The whole TCP/PLA hybrid scaffold was continuously colonized due to plasma polymerized allylamine activation inducing the migration potential of osteoblasts.

  17. Earthworm Activity and the Potential for Enhanced Leaching of Inorganic Elements in Soils

    NASA Astrophysics Data System (ADS)

    Gruau, G.; Ablain, F.; Cluzeau, D.

    2002-12-01

    the likely shorter soil-water interaction time). Although preliminary, these results suggest that earthworm activities can potentialy increase the leaching of a wide variety of inorganic elements in soils. This increase could occur through the ability of earthworms to change the biogeochemical conditions in the soil along their burrows (so-called drilosphere).

  18. Enzymatically synthesized inorganic polymers as morphogenetically active bone scaffolds: application in regenerative medicine.

    PubMed

    Wang, Xiaohong; Schröder, Heinz C; Müller, Werner E G

    2014-01-01

    In recent years a paradigm shift in understanding of human bone formation has occurred that starts to change current concepts in tissue engineering of bone and cartilage. New discoveries revealed that fundamental steps in biomineralization are enzyme driven, not only during hydroxyapatite deposition, but also during initial bioseed formation, involving the transient deposition and subsequent transformation of calcium carbonate to calcium phosphate mineral. The principal enzymes mediating these reactions, carbonic anhydrase and alkaline phosphatase, open novel targets for pharmacological intervention of bone diseases like osteoporosis, by applying compounds acting as potential activators of these enzymes. It is expected that these new findings will give an innovation boost for the development of scaffolds for bone repair and reconstruction, which began with the use of bioinert materials, followed by bioactive materials and now leading to functional regenerative tissue units. These new developments have become possible with the discovery of the morphogenic activity of bioinorganic polymers, biocalcit, bio-polyphosphate and biosilica that are formed by a biogenic, enzymatic mechanism, a driving force along with the development of novel rapid-prototyping three-dimensional (3D) printing methods and bioprinting (3D cell printing) techniques that may allow a fabrication of customized implants for patients suffering in bone diseases in the future.

  19. Trivalent metal ions based on inorganic compounds with in vitro inhibitory activity of matrix metalloproteinase 13.

    PubMed

    Wen, Hanyu; Qin, Yuan; Zhong, Weilong; Li, Cong; Liu, Xiang; Shen, Yehua

    2016-10-01

    Collagenase-3 (MMP-13) inhibitors have attracted considerable attention in recent years and have been developed as a therapeutic target for a variety of diseases, including cancer. Matrix metalloproteinases (MMPs) can be inhibited by a multitude of compounds, including hydroxamic acids. Studies have shown that materials and compounds containing trivalent metal ions, particularly potassium hexacyanoferrate (III) (K3[Fe(CN)6]), exhibit cdMMP-13 inhibitory potential with a half maximal inhibitory concentration (IC50) of 1.3μM. The target protein was obtained by refolding the recombinant histidine-tagged cdMMP-13 using size exclusion chromatography (SEC). The secondary structures of the refolded cdMMP-13 with or without metal ions were further analyzed via circular dichroism and the results indicate that upon binding with metal ions, an altered structure with increased domain stability was obtained. Furthermore, isothermal titration calorimetry (ITC) experiments demonstrated that K3[Fe(CN)6]is able to bind to MMP-13 and endothelial cell tube formation tests provide further evidence for this interaction to exhibit anti-angiogenesis potential. To the best of our knowledge, no previous report of an inorganic compound featuring a MMP-13 inhibitory activity has ever been reported in the literature. Our results demonstrate that K3[Fe(CN)6] is useful as a new effective and specific inhibitor for cdMMP-13 which may be of great potential for future drug screening applications. Copyright © 2016. Published by Elsevier Inc.

  20. MESOPOROUS IRON PHOSPHATE AS AN ACTIVE, SELECTIVE AND RECYCLABLE CATALYST FOR THE SYNTHESIS OF NOPOL BY PRINS CONDENSATION

    EPA Science Inventory


    Mesoporous iron phosphate is found to be a highly active and recyclable heterogeneous catalyst for the selective synthesis of nopol by Prins condensation of ?-pinene and paraformaldehyde in acetonitrile at 80 oC.



  1. The oxygen isotope composition of phosphate released from phytic acid by the activity of wheat and Aspergillus niger phytase

    NASA Astrophysics Data System (ADS)

    von Sperber, C.; Tamburini, F.; Brunner, B.; Bernasconi, S. M.; Frossard, E.

    2015-07-01

    Phosphorus (P) is an essential nutrient for living organisms. Under P-limiting conditions plants and microorganisms can exude extracellular phosphatases that release inorganic phosphate (Pi) from organic phosphorus compounds (Porg). Phytic acid (myo-inositol hexakisphosphate, IP6) is an important form of Porg in many soils. The enzymatic hydrolysis of IP6 by phytase yields available Pi and less phosphorylated inositol derivates as products. The hydrolysis of organic P compounds by phosphatases leaves an isotopic imprint on the oxygen isotope composition (δ18O) of released Pi, which might be used to trace P in the environment. This study aims at determining the effect of phytase on the oxygen isotope composition of released Pi. For this purpose, enzymatic assays with histidine acid phytases from wheat and Aspergillus niger were prepared using IP6, adenosine 5'-monophosphate (AMP) and glycerophosphate (GPO4) as substrates. For a comparison to the δ18O of Pi released by other extracellular enzymes, enzymatic assays with acid phosphatases from potato and wheat germ with IP6 as a substrate were prepared. During the hydrolysis of IP6 by phytase, four of the six Pi were released, and one oxygen atom from water was incorporated into each Pi. This incorporation of oxygen from water into Pi was subject to an apparent inverse isotopic fractionation (ϵ ~ 6 to 10 ‰), which was similar to that imparted by acid phosphatase from potato during the hydrolysis of IP6 (ϵ ~ 7 ‰), where less than three Pi were released. The incorporation of oxygen from water into Pi during the hydrolysis of AMP and GPO4 by phytase yielded a normal isotopic fractionation (ϵ ~ -12 ‰), similar to values reported for acid phosphatases from potato and wheat germ. We attribute this similarity in ϵ to the same amino acid sequence motif (RHGXRXP) at the active site of these enzymes, which leads to similar reaction mechanisms. We suggest that the striking

  2. Loaded Ce-Ag organic-inorganic hybrids and their antibacterial activity.

    PubMed

    Truffault, Laurianne; Rodrigues, Danilo Fernando; Salgado, Hérida Regida Nunes; Santilli, Celso Valentim; Pulcinelli, Sandra Helena

    2016-11-01

    There are requirements for surfaces with antibacterial properties in various technological fields. U-PEO hybrids with antibacterial properties were synthesized by the sol-gel process, incorporating combinations of cerium and silver salts at different silver molar fractions (0, 0.02, 0.05, 0.10, and 1) relative to the total amount of doped cations. The loaded hybrids were characterized by TGA, XRD, and Raman spectroscopy. Release tests were performed using UV-vis spectroscopy, and the antibacterial properties of the hybrids were studied in agar tests and turbidimetry assays. The nanostructural evolution of the hybrids during the release of the antibacterial agents was investigated by in situ SAXS. XRD results showed the presence of the AgCl crystalline phase in the loaded hybrids from a silver molar fraction of 0.05. Raman spectroscopy evidenced the interaction of silver cations with the polymeric part of the hybrid. SAXS results confirmed these interactions and showed that cerium species interacted with both organic and inorganic parts of the hybrids. The loaded U-PEO hybrids were found to release all the incorporated cerium in 1h, while the hybrid containing 100% of silver released only 78% of the incorporated silver. All the loaded hybrids displayed antibacterial activity against the Pseudomonas aeruginosa bacterium. The antibacterial activity was found to increase with silver molar fraction. Due to its high antibacterial activity and low silver molar fraction, the loaded hybrid with silver molar fraction of 0.10 seemed to be a good compromise between efficiency, esthetic transparency, and photostability. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. ATPases and phosphate exchange activities in magnesium chelatase subunits of Rhodobacter sphaeroides.

    PubMed

    Hansson, M; Kannangara, C G

    1997-11-25

    Three separate proteins, BchD, BchH, and BchI, together with ATP, insert magnesium into protoporphyrin IX. An analysis of ATP utilization by the subunits revealed the following: BchH catalyzed ATP hydrolysis at the rate of 0.9 nmol per min per mg of protein. BchI and BchD, tested individually, had no ATPase activity but, when combined, hydrolyzed ATP at the rate of 117.9 nmol/min per mg of protein. Magnesium ions were required for the ATPase activities of both BchH and BchI+D, and these activities were inhibited 50% by 2 mM o-phenanthroline. BchI additionally catalyzed a phosphate exchange reaction from ATP and ADP. We conclude that ATP hydrolysis by BchI+D is required for an activation step in the magnesium chelatase reaction, whereas ATPase activity of BchH and the phosphate exchange activity of BchI participate in subsequent reactions leading to the insertion of Mg2+ into protoporphyrin IX.

  4. Carbamoyl Phosphate Synthetase, Ornithine Transcarbamylase, and Aspartate Transcarbamylase Activities in the Pea Ovary 1

    PubMed Central

    Garcia-España, Antonio; Carbonell, Juan; Rubio, Vicente

    1989-01-01

    Carbamoyl phosphate synthetase (CPS), ornithine transcarbamylase (OTC), and aspartate transcarbamylase (ATC) were assayed in extracts from unpollinated ovaries of Pisum sativum L. CPS and OTC activities were, per milligram protein, the highest reported in a plant tissue, representing an estimated 0.1% of the protein in the ovary. The OTC/CPS and ATC/CPS ratios were about 100 and 0.5, respectively, indicating that most of the carbamoyl phosphate is used for arginine synthesis. The weight, protein content, and CPS, OTC, and ATC activities per ovary were determined during the senescence of the ovary and also during fruit set induced by treatment with gibberellic acid (GA3). In the nontreated ovary the weight and the protein first increased and then decreased dramatically, but the decrease in protein took place much earlier. In the GA3-treated ovaries the increase in weight was considerably greater than the increase in the protein. Whether or not the ovaries were treated with GA3, CPS, OTC, and ATC activities closely followed the changes in protein, and thus their ratios and specific activities remained essentially constant. It appears that treatment with GA3 increases the amount of protein and enzymic activities by preventing a large increase in the rate of protein degradation. In addition, the effects of acetylglutamate, ornithine, and UMP on CPS activity were studied. The pea enzyme exhibits regulatory properties intermediate between those of Escherichia coli and the ureotelic liver enzymes. PMID:16666966

  5. Studies on Anion Promoted Titania.1: Preparation, Characterization, and Catalytic Activity toward Alcohol and Cumene Conversion Reactions of Phosphated Titania.

    PubMed

    Parida; Acharya; Samantaray; Mishra

    1999-09-15

    Phosphate impregnated titania samples with varying amount of phosphate have been prepared by solid-solid kneading as well as aqueous impregnation method. All the samples are characterized by XRD, TG-DTA, and N(2) adsorption-desorption isotherm. Surface area is found to increase with the increase in phosphate content up to 7.5 wt% loading and thereafter decreases. The average pore diameter and crystallite size of titania decreases with the addition of phosphate. However, total acidity (determined by base adsorption method) and the catalytic activity increases with the increase in phosphate content up to 10 wt%. Phosphated samples prepared using phosphoric acid as the source of phosphate exhibit higher acidity compared to the samples prepared using (NH(4))(3)PO(4). However, the sample prepared from (NH(4))(3)PO(4) shows the presence of both acid and basic sites. Though from the cumene conversion study it is understood that phosphated samples contain both Lewis and Brønsted acid sites, the latter predominates over the former. Copyright 1999 Academic Press.

  6. Dietary P regulates phosphate transporter expression, phosphatase activity, and effluent P partitioning in trout culture.

    PubMed

    Coloso, R M; King, K; Fletcher, J W; Weis, P; Werner, A; Ferraris, R P

    2003-08-01

    Phosphate utilization by fish is an important issue because of its critical roles in fish growth and aquatic environmental pollution. High dietary phosphorus (P) levels typically decrease the efficiency of P utilization, thereby increasing the amount of P excreted as metabolic waste in effluents emanating from rainbow trout aquaculture. In mammals, vitamin D3 is a known regulator of P utilization but in fish, its regulatory role is unclear. Moreover, the effects of dietary P and vitamin D3 on expression of enzymatic and transport systems potentially involved in phosphate utilization are little known. We therefore monitored production of effluent P, levels of plasma vitamin D3 metabolites, as well as expression of phosphatases and the sodium phosphate cotransporter (NaPi2) in trout fed semipu diets that varied in dietary P and vitamin D3 levels. Mean soluble P concentrations varied markedly with dietary P but not with vitamin D3, and constituted 40-70% of total effluent P production by trout. Particulate P concentrations accounted for 25-50% of effluent P production, but did not vary with dietary P or vitamin D3. P in settleable wastes accounted for <10% of effluent P. The stronger effect of dietary P on effluent P levels is paralleled by its striking effects on phosphatases and NaPi2. The mRNA abundance of the intestinal and renal sodium phosphate transporters increased in fish fed low dietary P; vitamin D3 had no effect. Low-P diets reduced plasma phosphate concentrations. Intracellular phytase activity increased but brushborder alkaline phosphatase activity decreased in the intestine, pyloric caeca, and gills of trout fed diets containing low dietary P. Vitamin D3 had no effect on enzyme activities. Moreover, plasma concentrations of 25-hydroxyvitamin D3 and of 1,25-dihydroxyvitamin D3 were unaffected by dietary P and vitamin D3 levels. The major regulator of P metabolism, and ultimately of levels of P in the effluent from trout culture, is dietary P.

  7. Preparation of spherical calcium phosphate granulates suitable for the biofunctionalization of active brazed titanium alloy coatings.

    PubMed

    Schickle, Karolina; Gerardo-Nava, Jose L; Puidokas, Sabrina; Anavar, Sharareh Samadian; Bergmann, Christian; Gingter, Philipp; Schickle, Benjamin; Bobzin, Kirsten; Fischer, Horst

    2015-04-01

    Titanium-based alloys can be actively brazed onto bio-inert ceramics and potentially be used as biocompatible coatings. To further improve their bioactivity in vivo, introduction of calcium phosphate (CaP)-based granulates onto their surface layer is possible. For this, mechanically stable CaP-based granulates need to be able to withstand the demand of the brazing process. In this study, spherical granulates, made of a calcium phosphate composite composed primarily of β-tricalcium phosphate and hydroxyapatite, a bioactive glass, and a mixture of the previous two, were manufactured by spray drying. The influence of organic additives (Dolapix CE64, trisodium citrate) and solids content (30-80 wt%) in the slurry on the physical characteristics of granulates was investigated. X-ray diffraction, Brunauer, Emmett, Teller specific surface area standard method, scanning electron microscopy, granulate size analysis, and single granule strength were performed. Our results showed that trisodium citrate permitted the production of granulates with regular morphology, high density, and increased failure stress values. The strong granules also withstood the brazing process. These results show that CaP bioactive agents can be generated and be integrated during the demanding metallurgical processes, allowing for one-step bioactivation of metal brazes.

  8. Type I phosphatidylinositol 4-phosphate 5-kinase homo- and heterodimerization determines its membrane localization and activity.

    PubMed

    Lacalle, Rosa Ana; de Karam, Juan C; Martínez-Muñoz, Laura; Artetxe, Ibai; Peregil, Rosa M; Sot, Jesús; Rojas, Ana M; Goñi, Félix M; Mellado, Mario; Mañes, Santos

    2015-06-01

    Type I phosphatidylinositol 4-phosphate 5-kinases (PIP5KIs; α, β, and γ) are a family of isoenzymes that produce phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] using phosphatidylinositol 4-phosphate as substrate. Their structural homology with the class II lipid kinases [type II phosphatidylinositol 5-phosphate 4-kinase (PIP4KII)] suggests that PIP5KI dimerizes, although this has not been formally demonstrated. Neither the hypothetical structural dimerization determinants nor the functional consequences of dimerization have been studied. Here, we used Förster resonance energy transfer, coprecipitation, and ELISA to show that PIP5KIβ forms homo- and heterodimers with PIP5KIγ_i2 in vitro and in live human cells. Dimerization appears to be a general phenomenon for PIP5KI isoenzymes because PIP5KIβ/PIP5KIα heterodimers were also detected by mass spectrometry. Dimerization was independent of actin cytoskeleton remodeling and was also observed using purified proteins. Mutagenesis studies of PIP5KIβ located the dimerization motif at the N terminus, in a region homologous to that implicated in PIP4KII dimerization. PIP5KIβ mutants whose dimerization was impaired showed a severe decrease in PI(4,5)P2 production and plasma membrane delocalization, although their association to lipid monolayers was unaltered. Our results identify dimerization as an integral feature of PIP5K proteins and a central determinant of their enzyme activity.

  9. Influence of plant activity and phosphates on thorium bioavailability in soils from Baotou area, Inner Mongolia.

    PubMed

    Guo, Pengran; Jia, Xiaoyu; Duan, Taicheng; Xu, Jingwei; Chen, Hangting

    2010-09-01

    Harm of thorium to living organisms is governed by its bioavailability. Thorium bioavailability in the soil-plant system of Baotou rare earth industrial area was studied using pot experiments of wheat and single extraction methods. The effects of wheat growth stage and phosphate on thorium bioavailability were also investigated. Based on extractabilities of various extraction methods (CaCl(2), NH(4)NO(3), EDTA, HOAc) and correlation analysis of thorium uptake by wheat plant and extractable thorium, a mixture of 0.02M EDTA+0.5M NH(4)OAc (pH 4.6) was found suitable for evaluation of thorium bioavailability in Baotou soil, which could be predicted quantitatively by multiple regression models. Because of differences of wheat root activities, thorium bioavailability in rhizosphere soil was higher than in bulk soil at tillering stage, but the reverse occurred at jointing stage. Phosphate addition induced the mineralization of soluble thorium by forming stable thorium phosphate compounds, and reduced thorium bioavailability in soil.

  10. Inorganic nanoparticles and the immune system: detection, selective activation and tolerance

    NASA Astrophysics Data System (ADS)

    Bastús, Neus G.; Sánchez-Tilló, Ester; Pujals, Silvia; Comenge, Joan; Giralt, Ernest; Celada, Antonio; Lloberas, Jorge; Puntes, Victor F.

    2012-03-01

    The immune system is the responsible for body integrity and prevention of external invasion. On one side, nanoparticles are no triggers that the immune system is prepared to detect, on the other side it is known that foreign bodies, not only bacteria, viruses and parasites, but also inorganic matter, can cause various pathologies such as silicosis, asbestosis or inflammatory reactions. Therefore, nanoparticles entering the body, after interaction with proteins, will be either recognized as self-agents or detected by the immune system, encompassing immunostimulation or immunosuppression responses. The nature of these interactions seems to be dictated not specially by the composition of the material but by modifications of NP coating (composition, surface charge and structure). Herein, we explore the use of gold nanoparticles as substrates to carry multifunctional ligands to manipulate the immune system in a controlled manner, from undetection to immunostimulation. Murine bone marrow macrophages can be activated with artificial nanometric objects consisting of a gold nanoparticle functionalized with peptides. In the presence of some conjugates, macrophage proliferation was stopped and pro-inflammatory cytokines were induced. The biochemical type of response depended on the type of conjugated peptide and was correlated with the degree of ordering in the peptide coating. These findings help to illustrate the basic requirements involved in medical NP conjugate design to either activate the immune system or hide from it, in order to reach their targets before being removed by phagocytes. Additionally, it opens up the possibility to modulate the immune response in order to suppress unwanted responses resulting from autoimmunity, or allergy or to stimulate protective responses against pathogens.

  11. Antiarthritic and chondroprotective activity of Lakshadi Guggul in novel alginate-enclosed chitosan calcium phosphate nanocarriers.

    PubMed

    Samarasinghe, Rasika M; Kanwar, Rupinder K; Kumar, Kuldeep; Kanwar, Jagat R

    2014-05-01

    This study aimed to evaluate the antiarthritic and chondroprotective potentials of Lakshadi Guggul (LG) and Cissus quadrangularis encapsulated in novel alginate-enclosed chitosan-calcium phosphate nanocarriers (NCs) both in vitro in primary human chondrocytes and in vivo in mice with collagen-induced arthritis. Chondrocytes exposed to IL-1β and osteoarthritis chondrocytes grown in an ex vivo inflammation-based coculture were incubated with different concentrations of herbals, and cell modulatory activities were determined. For in vivo studies, herbals and their encapsulated nanoformulations were administered orally to DBA/1 mice with collagen-induced arthritis. C. quadrangularis and LG showed enhanced chondroprotective and proliferative activity in IL-1β-exposed primary chondrocytes, with LG showing the highest therapeutic potency. LG increased viability, proliferative and mitogenic activity, and inhibited cell apoptosis and mitochondrial depolarization. In vivo studies with LG and alginate-enclosed chitosan-calcium phosphate LG NCs revealed cartilage regenerative activity in those administered with the nanoformulation. The NCs were nontoxic to mice, reduced joint swelling and paw volume, and inhibited gene expression of MMPs and cytokines. The promising results from this study reveal, for the first time, the novel polymeric NC encapsulating LG as a potential therapeutic for rheumatic diseases.

  12. On the reactive adsorption of ammonia on activated carbons modified by impregnation with inorganic compounds

    SciTech Connect

    Bandosz, T.J.; Petit, C.

    2009-10-15

    Ammonia adsorption was studied under dynamic conditions, at room temperature, on activated carbons of different origins (coal-based, wood-based and coconut-shell-based carbons) before and after their impregnation with various inorganic compounds including metal chlorides, metal oxides and polycations. The role of humidity was evaluated by running tests in both dry and moist conditions. Adsorbents were analyzed before and after exposure to ammonia by thermal analyses, sorption of nitrogen, potentiometric titration, X-ray diffraction and FTIR spectroscopy. Results of breakthrough tests show significant differences in terms of adsorption capacity depending on the parent carbon, the impregnates and the experimental conditions. It is found that surface chemistry governs ammonia adsorption on the impregnated carbons. More precisely, it was demonstrated that a proper combination of the surface pH, the strength, type and amount of functional groups present on the adsorbents' surface is a key point in ammonia uptake. Water can have either positive or negative effects on the performance of adsorbents. It can enhance NH{sub 3} adsorption capacity since it favors ammonia dissolution and thus enables reaction between ammonium ions and carboxylic groups from the carbons' surface. On the other hand, water can also reduce the performance from the strength of adsorption standpoint. It promotes dissolution of ammonia and that ammonia is first removed from the system when the adsorbent bed is purged with air. Ammonia, besides adsorption by van der Waals forces and dissolution in water, is also retained on the surface via reactive mechanisms such as acid-base reactions (Bronsted and Lewis) or complexation. Depending on the materials used and the experimental conditions, 6-47% ammonia adsorbed is strongly retained on the surface even when the bed is purged with air.

  13. On the reactive adsorption of ammonia on activated carbons modified by impregnation with inorganic compounds.

    PubMed

    Bandosz, Teresa J; Petit, Camille

    2009-10-15

    Ammonia adsorption was studied under dynamic conditions, at room temperature, on activated carbons of different origins (coal-based, wood-based and coconut-shell-based carbons) before and after their impregnation with various inorganic compounds including metal chlorides, metal oxides and polycations. The role of humidity was evaluated by running tests in both dry and moist conditions. Adsorbents were analyzed before and after exposure to ammonia by thermal analyses, sorption of nitrogen, potentiometric titration, X-ray diffraction and FTIR spectroscopy. Results of breakthrough tests show significant differences in terms of adsorption capacity depending on the parent carbon, the impregnates and the experimental conditions. It is found that surface chemistry governs ammonia adsorption on the impregnated carbons. More precisely, it was demonstrated that a proper combination of the surface pH, the strength, type and amount of functional groups present on the adsorbents' surface is a key point in ammonia uptake. Water can have either positive or negative effects on the performance of adsorbents. It can enhance NH(3) adsorption capacity since it favors ammonia dissolution and thus enables reaction between ammonium ions and carboxylic groups from the carbons' surface. On the other hand, water can also reduce the performance from the strength of adsorption standpoint. It promotes dissolution of ammonia and that ammonia is first removed from the system when the adsorbent bed is purged with air. Ammonia, besides adsorption by van der Waals forces and dissolution in water, is also retained on the surface via reactive mechanisms such as acid-base reactions (Brønsted and Lewis) or complexation. Depending on the materials used and the experimental conditions, 6-47% ammonia adsorbed is strongly retained on the surface even when the bed is purged with air.

  14. Alkalosis and Dialytic Clearance of Phosphate Increases Phosphatase Activity: A Hidden Consequence of Hemodialysis

    PubMed Central

    Villa-Bellosta, Ricardo; González-Parra, Emilio; Egido, Jesús

    2016-01-01

    Background Extracellular pyrophosphate is a potent endogenous inhibitor of vascular calcification, which is degraded by alkaline phosphatase (ALP) and generated by hydrolysis of ATP via ectonucleotide pyrophosphatase/phosphodiesterase 1 (eNPP1). ALP activity (as routinely measured in clinical practice) represents the maximal activity (in ideal conditions), but not the real activity (in normal or physiological conditions). For the first time, the present study investigated extracellular pyrophosphate metabolism during hemodialysis sessions (including its synthesis via eNPP1 and its degradation via ALP) in physiological conditions. Methods and Findings 45 patients in hemodialysis were studied. Physiological ALP activity represents only 4–6% of clinical activity. ALP activity increased post-hemodialysis by 2% under ideal conditions (87.4 ± 3.3 IU/L vs. 89.3 ± 3.6 IU/L) and 48% under physiological conditions (3.5 ± 0.2 IU/L vs. 5.2 ± 0.2 IU/L). Pyrophosphate synthesis by ATP hydrolysis remained unaltered post-hemodialysis. Post-hemodialysis plasma pH (7.45 ± 0.02) significantly increased compared with the pre-dialysis pH (7.26 ± 0.02). The slight variation in pH (~0.2 units) induced a significant increase in ALP activity (9%). Addition of phosphate in post-hemodialysis plasma significantly decreased ALP activity, although this effect was not observed with the addition of urea. Reduction in phosphate levels and increment in pH were significantly associated with an increase in physiological ALP activity post-hemodialysis. A decrease in plasma pyrophosphate levels (3.3 ± 0.3 μmol/L vs. 1.9 ± 0.1 μmol/L) and pyrophosphate/ATP ratio (1.9 ± 0.2 vs. 1.4 ± 0.1) post-hemodialysis was also observed. Conclusion Extraction of uremic toxins, primarily phosphate and hydrogen ions, dramatically increases the ALP activity under physiological conditions. This hitherto unknown consequence of hemodialysis suggests a reinterpretation of the clinical value of this parameter

  15. Erythrocyte pyridoxamine phosphate oxidase activity: a potential biomarker of riboflavin status?

    PubMed

    Mushtaq, Sohail; Su, Han; Hill, Marilyn H E; Powers, Hilary J

    2009-11-01

    Riboflavin status is commonly measured by the in vitro stimulation of erythrocyte glutathione reductase with flavin adenine dinucleotide and expressed as an erythrocyte glutathione reductase activation coefficient (EGRAC). However, this assay is insensitive to poor riboflavin status in subjects with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Because G6PD deficiency is common in parts of the world where ariboflavinosis is endemic, it is important to have a measure of riboflavin status that is unaffected by differences in G6PD status. The objective was to further develop and validate a fluorometric assay for pyridoxamine phosphate oxidase (PPO) activity as a measure of riboflavin status. A fluorometric assay was optimized for the flavin-dependent enzyme PPO in erythrocytes. Hemolysates from a previous riboflavin intervention study (2- and 4-mg riboflavin supplements) were used to investigate the responsiveness of the method to changes in riboflavin intake. PPO activity and the PPO activation coefficient (PPOAC) were used to assess riboflavin status. Both PPO activity and PPOAC responded to riboflavin supplements (P < 0.01), but only PPO showed a dose response (P < 0.001). The change from baseline to after the intervention in PPOAC and PPO enzyme activity was significantly inversely correlated (P < 0.001). Both PPO activity and PPOAC were strongly correlated with EGRAC (P < 0.001). Additionally, both PPOAC and EGRAC showed a significant inverse correlation with dietary riboflavin intake (P < 0.01); PPO activity was positively correlated with riboflavin intake (P < 0.01). PPO activity could be used as a biomarker for measuring riboflavin status, especially in populations with a high prevalence of G6PD deficiency. This trial is registered at www.isrctn.org as ISRCTN35811298.

  16. Effect of chloroquine phosphate and toxic concentrations of lead acetate on Ca2+-ATPase activity in isolates and clones of Plasmodium falciparum.

    PubMed

    Bolaji, O M; Happi, T C; Oduola, A M J; Babafunmi, E A

    2011-12-20

    The basal activity of Ca2+-ATPase in two isolates (NL56, UNC) and two clones (D6, W2) of P.falciparum was assessed. The effects of various concentrations of chloroquine phosphate and toxic concentrations of lead acetate were also evaluated in the clones and strains of P.falciparum. The Ca2+-ATPase activity was measured by monitoring the rate of release of inorganic phosphate from the gamma-position of ATP on spectrophotometer at 820nm wavelength. The various concentrations of chloroquine (3, 6, 9, 12, 18µg/ml) and lead acetate (5, 10, 20, 30, 40µg/ml) on Ca2+-ATPase activity were measured respectively. Chloroquine phosphate inhibited Ca2+-ATPase activity in both the isolates and the cloned strains of P.falciparum in concentration dependent manner. Median Inhibitory concentration of chloroquine (MIC50) estimated from the plot of activity against chloroquine concentration was found to be 2.6mg/ml at pH 7.4 for both the isolates and cloned strains examined. Lead acetate at concentrations 5-20µg/ml inhibited Ca2+-ATPase activity in concentration dependent manner in clone W2 (Chloroquine resistant strain) while the same range of concentrations of lead acetate stimulated the activity of the enzyme in clone D6 (Chloroquine sensitive strain).The inhibitory effect of lead acetate on the enzyme in clone D6 was observed at concentrations above 20µg/ml. The result also suggests that lead ions could modulate and moderate calcium ion homeostasis in P. falciparum via its effect on Ca2+-ATPase activity. Also sufficient influx of lead ions into P. falciparum may transform the biochemical or bioenergetics nature of chloroquine sensitive strain of P. falciparum (D6) to that similar to chloroquine resistant strain (W2). In conclusion, inhibition of Ca2+-ATPase activity of P.falciparum may be part of the mechanism of action of chloroquine in its use as chemotherapy for malaria. The study implies that populations simultaneously exposed to lead pollution and malaria infection may

  17. ACTIVE MEDIA. LASERS: Diode-array-pumped repetitively pulsed neodymium phosphate glass laser

    NASA Astrophysics Data System (ADS)

    Bogatov, A. P.; Drakin, A. E.; Miftakhutdinov, D. R.; Mikaelyan, G. T.; Starodub, A. N.

    2008-09-01

    Repetitively pulsed generation (200 μs, 40 Hz) was obtained in a neodymium phosphate glass laser pumped by a 870-nm diode array. The maximum slope lasing efficiency with respect to the optical pump energy equal to 13% is restricted by the factor (≈0.23) of active-medium filling by the mode field. By adjusting the laser cavity, the single-transverse mode regime, in particular, the generation of the TEM00 mode is obtained in the entire range of pump energies.

  18. EFFECT OF PHOSPHATE ION AND 2,4-DINITROPHENOL ON THE ACTIVITY OF INTACT CELLS OF THIOBACILLUS FERROOXIDANS

    PubMed Central

    Beck, Jay V.; Shafia, Fred M.

    1964-01-01

    Beck, Jay V. (Brigham Young University, Provo, Utah), and Fred M. Shafia. Effect of phosphate ion and 2,4-dinitrophenol on the activity of cell suspensions of Thiobacillus ferrooxidans. J. Bacteriol. 88:850–857. 1964.—The rate of oxidation of ferrous salts or elemental sulfur by aged cell suspensions, phosphate-depleted cells, or 2,4-dinitrophenol (DNP)-treated cells of Thiobacillus ferrooxidans was increased by addition of orthophosphate salts. The effect was found to be transitory, with the rate gradually approaching that observed prior to phosphate ion addition. The total increased oxygen uptake was observed to be roughly proportional to the amount of phosphate salt added. The efficiency of CO2 fixation accompanying oxidation of ferrous salts was found to be about 1.7 μmoles of CO2 fixed per 100 μmoles of O2 absorbed, in contrast to a value of about 8.0 μmoles of CO2 fixed per 100 μmoles of O2 uptake during sulfur oxidation. The rate of oxidation did not affect the CO2 fixation efficiency. Whereas addition of phosphate salts to aged or phosphate-depleted cells increased slightly the already high efficiency of CO2 fixation, it did not affect the complete inhibition of CO2 fixation observed in the presence of 10-5m DNP. The results indicate that the phosphate ion is essential for oxidation of the ferrous ion, and that dinitrophenol and other so-called upcoupling agents interfere with phosphate metabolism. The latter may be a result of action at the site of assimilation of the ferrous ion or it may be an effect on the electron-transport system. In any event, it seems obvious that the phosphate ion is converted into a nonactive form in the presence of dinitrophenol-treated cells, because additional quantities of orthophosphate salts cause an immediate, marked restoration of oxidative activity. PMID:14219046

  19. Enhancing the value of commodity polymers: Part 1. Structure-property relationships in composite materials based on maleated polypropylene/inorganic phosphate glasses. Part 2. New value-added applications for polyesters

    NASA Astrophysics Data System (ADS)

    Gupta, Mohit

    The first part of the thesis (Chapters 2 & 3) describes a new class of organic polymer/inorganic glass composite materials with property improvements that are impossible to achieve with classical polymer blends or composites. These materials exhibit good processability, superior mechanical performance, good thermal stability, and have excellent gas barrier properties. Low glass transition temperature phosphate glasses (Pglass) are used as inorganic fillers and slightly maleated polypropylene is used as the organic polymer matrix. The Pglass, which was dispersed as spherical droplets in the unoriented composites can be elongated into high aspect ratio platelets during the biaxial stretching process. Biaxially oriented films exhibited a brick wall type microstructure with highly aligned inorganic platelets in a ductile organic matrix and the oxygen barrier properties are significantly improved due to presence of Pglass platelets as impermeable inclusions. Mechanical properties of the biaxially oriented films showed significant improvements compared to neat polymer due to uniform dispersion of the Pglass platelets. Properly dispersed and aligned platelets have proven to be very effective for increasing the composite modulus. These developed materials therefore show promise to help fulfill the ever increasing demand for new advanced materials for a wide variety of advanced packaging applications because of their gas barrier properties, flexibility, transparency, mechanical strength and performance under humid conditions. The second part of the thesis (Chapters 4 & 5) describes new value-added applications for polyesters. Chapter 4 reports a novel process for the decolorization of green and blue colored PET bottle flakes using hydrogen peroxide. The decolorized flakes were characterized for color, intrinsic viscosity values. Decolorized flakes exhibited color values similar to those of colorless recycled PET and even though IV values decreased, bleached flakes still

  20. Glutathion peroxidase and glucose-6-phosphate dehydrogenase activities in bovine blood and liver.

    PubMed

    Abd Ellah, Mahmoud Rushdi; Niishimori, Kazuhiro; Goryo, Masanobu; Okada, Keiji; Yasuda, Jun

    2004-10-01

    A total of 46 cattle, including 25 as control, 16 with glycogen degeneration and 5 with severe fatty degeneration were studied. Whole blood and liver tissue specimens were used to measure glutathione peroxidase (GSH-Px) and Glucose-6-Phosphate Dehydrogenase (G6PD) activities. The present study determined the value of these parameters in diagnosing glycogen and fatty degeneration in cattle from the point of the status of antioxidation and lipid peroxidation. The results showed a significant decrease in hepatic GSH-Px activity and a significant increase in hepatic G6PD activity in cases of fatty degeneration. On the other hand, there were no significant changes in erythrocytic and hepatic GSH-Px and G6PD activities in cases of glycogen degeneration. The results indicated lipoperoxidation process in the liver tissues increased in cases of fatty degeneration. Therefore, supplying animals suffering from fatty liver with sufficient quantities of nutrient antioxidants may be valuable when treatment is considered.

  1. Protein phosphorylation as a mechanism for regulation of spinach leaf sucrose-phosphate synthase activity

    SciTech Connect

    Huber, J.L.A.; Huber, S.C. )

    1989-04-01

    Protein phosphorylation has been identified as a mechanism for the light-dark regulation of spinach sucrose-phosphate synthase (SPS) activity, previously shown to involve some type of covalent modification of the enzyme. The 120 kD subunit of SPS in extracts of light-treated leaves was labeled with {sup 32}P in the presence of ({gamma}-{sup 32}P) ATP. In this in vitro system, {sup 32}P incorporation into light-activated SPS was dependent upon ATP and magnesium concentrations as well as time, and was closely paralleled by inactivation of the enzyme. The soluble protein kinase involved in the interconversion of SPS between activated and deactivated forms may be specific for SPS as it co-purifies with SPS during partial purification of the enzyme. The kinase appears not to be calcium activated and no evidence has been obtained for metabolite control of SPS phosphorylation/inactivation.

  2. Spontaneous activation of [FeFe]-hydrogenases by an inorganic [2Fe] active site mimic

    PubMed Central

    Esselborn, Julian; Berggren, Gustav; Noth, Jens; Siebel, Judith; Hemschemeier, Anja; Artero, Vincent; Reijerse, Edward; Fontecave, Marc; Lubitz, Wolfgang; Happe, Thomas

    2013-01-01

    Hydrogenases catalyze the formation of hydrogen. The cofactor (H-cluster) of [FeFe]-hydrogenases consists of a [4Fe-4S]-cluster bridged to a unique [2Fe]-subcluster whose biosynthesis in vivo requires hydrogenase-specific maturases. Here we show that a chemical mimic of the [2Fe]-subcluster can reconstitute apo-hydrogenase to full activity, independent of helper proteins. The assembled H-cluster is virtually indistinguishable from the native cofactor. This procedure will be a powerful tool for developing novel artificial H2-producing catalysts. PMID:23934246

  3. Inorganic arsenic represses interleukin-17A expression in human activated Th17 lymphocytes

    SciTech Connect

    Morzadec, Claudie; Macoch, Mélinda; Robineau, Marc; Sparfel, Lydie; Fardel, Olivier; Vernhet, Laurent

    2012-08-01

    Trivalent inorganic arsenic [As(III)] is an efficient anticancer agent used to treat patients suffering from acute promyelocytic leukemia. Recently, experimental studies have clearly demonstrated that this metalloid can also cure lymphoproliferative and/or pro-inflammatory syndromes in different murine models of chronic immune-mediated diseases. T helper (Th) 1 and Th17 lymphocytes play a central role in development of these diseases, in mice and humans, especially by secreting the potent pro-inflammatory cytokine interferon-γ and IL-17A, respectively. As(III) impairs basic functions of human T cells but its ability to modulate secretion of pro-inflammatory cytokines by differentiated Th lymphocytes is unknown. In the present study, we demonstrate that As(III), used at concentrations clinically achievable in plasma of patients, has no effect on the secretion of interferon-γ from Th1 cells but almost totally blocks the expression and the release of IL-17A from human Th17 lymphocytes co-stimulated for five days with anti-CD3 and anti-CD28 antibodies, in the presence of differentiating cytokines. In addition, As(III) specifically reduces mRNA levels of the retinoic-related orphan receptor (ROR)C gene which encodes RORγt, a key transcription factor controlling optimal IL-17 expression in fully differentiated Th17 cells. The metalloid also blocks initial expression of IL-17 gene induced by the co-stimulation, probably in part by impairing activation of the JNK/c-Jun pathway. In conclusion, our results demonstrate that As(III) represses expression of the major pro-inflammatory cytokine IL-17A produced by human Th17 lymphocytes, thus strengthening the idea that As(III) may be useful to treat inflammatory immune-mediated diseases in humans. -- Highlights: ► Arsenic inhibits secretion of IL-17A from human naïve and memory Th17 lymphocytes. ► Arsenic represses early expression of IL-17A gene in human activated T lymphocytes. ► Arsenic interferes with activation of

  4. Sphingosine 1-phosphate, present in serum-derived lipoproteins, activates matriptase.

    PubMed

    Benaud, Christelle; Oberst, Michael; Hobson, John P; Spiegel, Sarah; Dickson, Robert B; Lin, Chen-Yong

    2002-03-22

    We describe here a novel biological function of sphingosine 1-phosphate (S1P): the activation of a serine protease, matriptase. Matriptase is a type II integral membrane serine protease, expressed on the surface of a variety of epithelial cells; it may play an important role in tissue remodeling. We have previously reported that the activation of matriptase is regulated by serum. We have now identified the bioactive component from serum. First, the activity was observed to co-purify with lipoproteins by conventional liquid chromatography and immunoaffinity chromatography. The ability of lipoproteins to induce the activation of matriptase was further confirmed with commercial preparations of low density lipoprotein (LDL) and very low density lipoprotein (VLDL). Next, we observed that the bioactive component of LDL is associated with the phospholipid components of LDL. Fractionation of lipid components of LDL by thin layer chromatography (TLC) revealed that the bioactive component of LDL comigrates with S1P. Nanomolar concentrations of commercially obtained S1P were then observed to induce the rapid activation of matriptase on the surfaces of nontransformed human mammary epithelial cells. Other structurally related sphingolipids, including dihydro-S1P, ceramide 1-phosphates, and sphingosine phosphocholine as well as lysophosphatidic acid, can also induce the activation of matriptase, but at significantly higher concentrations than S1P. Furthermore, S1P-dependent matriptase activation is dependent on Ca(2+) but not via G(i) protein-coupled receptors. Our results demonstrate that bioactive phospholipids can function as nonprotein activators of a cell surface protease, suggesting a possible mechanistic link between S1P and normal and possibly pathologic tissue remodeling.

  5. Conformational and activity changes during guanidine denaturation of D-glyceraldehyde-3-phosphate dehydrogenase.

    PubMed

    Xie, G F; Tsou, C L

    1987-01-05

    Changes in intrinsic protein fluorescence of lobster muscle D-glyceraldehyde-3-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate: NAD+ oxidoreductase (phosphorylating), EC 1.2.1.12) have been compared with inactivation of the enzyme during denaturation in guanidine solutions. The holoenzyme is completely inactivated at guanidine concentrations less than 0.5 M and this is accompanied by a red shift of the emission maximum at 335 nm and a marked decrease in intensity of the intrinsic fluorescence. At 0.5 M guanidine, the inactivation is a slow process, with a first-order rate constant of 2.4 X 10(-3) s-1. A further red shift in the emission maximum and a decrease in intensity occur at guanidine concentrations higher than 1.5 M. The emission peak at 410 nm of the fluorescent NAD derivative introduced at the active site of this enzyme (Tsou, C.L. et al. (1983) Biochem. Soc. Trans. 11, 425-429) shows both a red shift and a marked decrease in intensity at the same guanidine concentration required to bring about the inactivation and the initial changes in the intrinsic fluorescence of the holoenzyme. It appears that treatment by low guanidine concentrations leads to both complete inactivation and perturbation of the active site conformation and that a tryptophan residue is situated at or near the active site.

  6. Enhancing phosphorus release from waste activated sludge containing ferric or aluminum phosphates by EDTA addition during anaerobic fermentation process.

    PubMed

    Zou, Jinte; Zhang, Lili; Wang, Lin; Li, Yongmei

    2017-03-01

    The effect of ethylene diamine tetraacetic acid (EDTA) addition on phosphorus release from biosolids and phosphate precipitates during anaerobic fermentation was investigated. Meanwhile, the impact of EDTA addition on the anaerobic fermentation process was revealed. The results indicate that EDTA addition significantly enhanced the release of phosphorus from biosolids, ferric phosphate precipitate and aluminum phosphate precipitate during anaerobic fermentation, which is attributed to the complexation of metal ions and damage of cell membrane caused by EDTA. With the optimal EDTA addition of 19.5 mM (0.41 gEDTA/gSS), phosphorus release efficiency from biosolids was 82%, which was much higher than that (40%) without EDTA addition. Meanwhile, with 19.5 mM EDTA addition, almost all the phosphorus in ferric phosphate precipitate was released, while only 57% of phosphorus in aluminum phosphate precipitate was released. This indicates that phosphorus in ferric phosphate precipitate was much easier to be released than that in aluminum phosphate precipitate during anaerobic fermentation of sludge. In addition, proper EDTA addition facilitated the production of soluble total organic carbon and volatile fatty acids, as well as solid reduction during sludge fermentation, although methane production could be inhibited. Therefore, EDTA addition can be used as an alternative method for recovering phosphorus from waste activated sludge containing ferric or aluminum precipitates, as well as recovery of soluble carbon source.

  7. Regulation of serum phosphate

    PubMed Central

    Lederer, Eleanor

    2014-01-01

    The regulation of serum phosphate, an acknowledged risk factor for chronic kidney disease and cardiovascular mortality, is poorly understood. The discovery of fibroblast growth factor 23 (FGF23) as a key regulator of renal phosphate handling and activation of vitamin D has revolutionized our comprehension of phosphate homeostasis. Through as yet undetermined mechanisms, circulating and dietary phosphate appear to have a direct effect on FGF23 release by bone cells that, in turn, causes renal phosphate excretion and decreases intestinal phosphate absorption through a decrease in vitamin D production. Thus, the two major phosphaturic hormones, PTH and FGF23, have opposing effects on vitamin D production, placing vitamin D at the nexus of phosphate homeostasis. While our understanding of phosphate homeostasis has advanced, the factors determining regulation of serum phosphate level remain enigmatic. Diet, time of day, season, gender, age and genetics have all been identified as significant contributors to serum phosphate level. The effects of these factors on serum phosphate have major implications for what is understood as ‘normal’ and for studies of phosphate homeostasis and metabolism. Moreover, other hormonal mediators such as dopamine, insulin-like growth factor, and angiotensin II also affect renal handling of phosphate. How the major hormone effects on phosphate handling are regulated and how the effect of these other factors are integrated to yield the measurable serum phosphate are only now beginning to be studied. PMID:24973411

  8. Phosphate, inositol and polyphosphates.

    PubMed

    Livermore, Thomas M; Azevedo, Cristina; Kolozsvari, Bernadett; Wilson, Miranda S C; Saiardi, Adolfo

    2016-02-01

    Eukaryotic cells have ubiquitously utilized the myo-inositol backbone to generate a diverse array of signalling molecules. This is achieved by arranging phosphate groups around the six-carbon inositol ring. There is virtually no biological process that does not take advantage of the uniquely variable architecture of phosphorylated inositol. In inositol biology, phosphates are able to form three distinct covalent bonds: phosphoester, phosphodiester and phosphoanhydride bonds, with each providing different properties. The phosphoester bond links phosphate groups to the inositol ring, the variable arrangement of which forms the basis of the signalling capacity of the inositol phosphates. Phosphate groups can also form the structural bridge between myo-inositol and diacylglycerol through the phosphodiester bond. The resulting lipid-bound inositol phosphates, or phosphoinositides, further expand the signalling potential of this family of molecules. Finally, inositol is also notable for its ability to host more phosphates than it has carbons. These unusual organic molecules are commonly referred to as the inositol pyrophosphates (PP-IPs), due to the presence of high-energy phosphoanhydride bonds (pyro- or diphospho-). PP-IPs themselves constitute a varied family of molecules with one or more pyrophosphate moiety/ies located around the inositol. Considering the relationship between phosphate and inositol, it is no surprise that members of the inositol phosphate family also regulate cellular phosphate homoeostasis. Notably, the PP-IPs play a fundamental role in controlling the metabolism of the ancient polymeric form of phosphate, inorganic polyphosphate (polyP). Here we explore the intimate links between phosphate, inositol phosphates and polyP, speculating on the evolution of these relationships. © 2016 Authors; published by Portland Press Limited.

  9. [Adsorption Characteristics of Nitrate and Phosphate from Aqueous Solution on Zirconium-Hexadecyltrimethylammonium Chloride Modified Activated Carbon].

    PubMed

    Zheng, Wen-jing; Lin, Jian-wei; Zhan, Yan-hui; Wang, Hong

    2015-06-01

    A novel adsorbent material, i.e., zirconium-cationic surfactant modified activated carbon (ZrSMAC) was prepared by loading zirconium hydroxide and hexadecyltrimethylammonium chloride (CTAC) on activated carbon, and was used as an adsorbent for nitrate and phosphate removal from aqueous solution. The adsorption characteristics of nitrate and phosphate on ZrSMAC from aqueous solution were investigated in batch mode. Results showed that the ZrSMAC was effective for nitrate and phosphate removal from aqueous solution. The pseudo-second-order kinetic model fitted both the nitrate and phosphate kinetic experimental data well. The equilibrium isotherm data of nitrate adsorption onto the ZrSMAC were well fitted to the Langmuir, Dubinin-Radushkevich (D-R) and Freundlich isotherm models. The equilibrium isotherm data of phosphate adsorption onto the ZrSMAC could be described by the Langmuir and,D- R isotherm models. According to the Langmuir isotherm model, the maximum nitrate and phosphate adsorption capacities for the ZrSMAC were 7.58 mg x g(-1) and 10.9 mg x g(-1), respectively. High pH value was unfavorable for nitrate and phosphate adsorption onto the ZrSMAC. The presence of Cl-, HCO3- and SO4(2-) in solution reduced the nitrate and phosphate adsorption capacities for the ZrSMAC. The nitrate adsorption capacity for the ZrSMAC was reduced by the presence of coexisting phosphate in solution, and the phosphate adsorption capacity for the ZrSMAC was also reduced by the presence of coexisting nitrate in solution. About 90% of nitrate adsorbed on the ZrSMAC could be desorbed in 1 mol x L(-1) NaCl solution, and about 78% of phosphate adsorbed on the ZrSMAC could be desorbed in 1 mol x L(-1) NaOH solution. The adsorption mechanism of nitrate on the ZrSMAC included the anion exchange interactions and electrostatic attraction, and the adsorption mechanism of phosphate on the ZrSMAC included the ligand exchange interaction, electrostatic attraction and anion exchange interaction.

  10. Lupus anticoagulant activities of murine monoclonal antibodies to liposomal phosphatidylinositol phosphate.

    PubMed

    Alving, B M; Banerji, B; Fogler, W E; Alving, C R

    1987-08-01

    Four murine monoclonal antibodies having high levels of activity against phosphatidyl-inositol phosphate (PIP) were tested for lupus anticoagulant activity. The antibodies showed different degrees of potency in a modified partial thromboplastin time test (APTT) that used dilutions of either bovine brain extract (Thrombofax) or liposomes consisting of phosphatidylcholine/phosphatidylserine (PC/PS) as the phospholipid source. The same relative order of anticoagulant potency that was observed in the APTT that used the PC/PS liposomes was maintained when the anti-PIP antibodies were tested for cross-reactivity either by induction of complement-dependent immune damage to liposomes containing PS, or in enzyme-linked immunosorbent assays that used PS, cardiolipin (CL), or phosphatidylinositol (PI) as antigens. The data indicate that monoclonal antibodies to PIP can express anticoagulant activity in a modified APTT that correlates with their different degrees of cross-reactivity against the negatively-charged phospholipids PS, CL, and PI.

  11. Lupus anticoagulant activities of murine monoclonal antibodies to liposomal phosphatidylinositol phosphate.

    PubMed Central

    Alving, B M; Banerji, B; Fogler, W E; Alving, C R

    1987-01-01

    Four murine monoclonal antibodies having high levels of activity against phosphatidyl-inositol phosphate (PIP) were tested for lupus anticoagulant activity. The antibodies showed different degrees of potency in a modified partial thromboplastin time test (APTT) that used dilutions of either bovine brain extract (Thrombofax) or liposomes consisting of phosphatidylcholine/phosphatidylserine (PC/PS) as the phospholipid source. The same relative order of anticoagulant potency that was observed in the APTT that used the PC/PS liposomes was maintained when the anti-PIP antibodies were tested for cross-reactivity either by induction of complement-dependent immune damage to liposomes containing PS, or in enzyme-linked immunosorbent assays that used PS, cardiolipin (CL), or phosphatidylinositol (PI) as antigens. The data indicate that monoclonal antibodies to PIP can express anticoagulant activity in a modified APTT that correlates with their different degrees of cross-reactivity against the negatively-charged phospholipids PS, CL, and PI. PMID:2820640

  12. 3D correlation NMR spectrum between three distinct heteronuclei for the characterization of inorganic samples: Application on sodium alumino-phosphate materials.

    PubMed

    Nagashima, Hiroki; Tricot, Grégory; Trébosc, Julien; Lafon, Olivier; Amoureux, Jean-Paul; Pourpoint, Frédérique

    2017-03-22

    We report here an original NMR sequence allowing the acquisition of 3D correlation NMR spectra between three distinct heteronuclei, among which two are half-integer spin quadrupolar nuclei. Furthermore, as two of them exhibit close Larmor frequency, this experiment was acquired using a standard triple-resonance probe equipped with a commercial frequency splitter. This NMR technique was tested and applied to sodium alumino-phosphate compounds with (31)P as the spin-1/2 nucleus and (23)Na and (27)Al as the close Larmor frequencies isotopes. To the best of our knowledge, such experiment with direct (31)P and indirect (27)Al and (23)Na detection is the first example of 3D NMR experiment in solids involving three distinct heteronuclei. This sequence has first been demonstrated on a mixture of Al(PO3)3 and NaAlP2O7 crystalline phases, for which a selective observation of NaAlP2O7 is possible through the 3D map edition. This 3D correlation experiment is then applied to characterize mixing and phase segregation in a partially devitrified glass that has been proposed as a material for the sequestration of radioactive waste. The (31)P-{(23)Na,(27)Al} 3D experiment conducted on the partially devitrified glass material conclusively demonstrates that the amorphous component of the material does not contain aluminum. The as-synthesized material thus presents a poor resistance against water, which is a severe limitation for its application in the radioactive waste encapsulation domain.

  13. Mechanism of lead immobilization by oxalic acid-activated phosphate rocks.

    PubMed

    Jiang, Guanjie; Liu, Yonghong; Huang, Li; Fu, Qingling; Deng, Youjun; Hu, Hongqing

    2012-01-01

    Lead (Pb) chemical fixation is an important environmental aspect for human health. Phosphate rocks (PRs) were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs (APRs) were used to investigate the effect of chemical modification on the Pb-binding capacity in the pH range 2.0-5.0. The Pb adsorption rate of all treatments above pH 3.0 reached 90%. The Pb binding on PRs and APRs was pH-independent, except at pH 2.0 in activated treatments. The X-ray diffraction analysis confirmed that the raw PRs formed cerussite after reacting with the Pb solution, whereas the APRs formed pyromorphite. The Fourier Transform Infrared spectroscopy analysis indicated that carbonate (CO3(2-)) in raw PRs and phosphate (PO4(3)) groups in APRs played an important role in the Pb-binding process. After adsorption, anomalous block-shaped particles were observed by scanning electron microscopy with energy dispersive spectroscopy. The X-ray photoelectron spectroscopy data further indicated that both chemical and physical reactions occurred during the adsorption process according to the binding energy. Because of lower solubility of pyromorphite compared to cerussite, the APRs are more effective in immobilizing Pb than that of PRs.

  14. [Point contacts of T7 RNA polymerase in the promotor complex, as determined with phosphate-activated oligonucleotide derivatives].

    PubMed

    Filippova, S E; Ivanovskaia, M G; Romanova, E A; Tunitskaia, V L; Kochetkov, S N

    2002-01-01

    The contacts between phosphate groups of promoter DNA an Lys or His of T7 RNA polmerase (Pol) in the Pol-promoter complex were studied with single- and double- stranded oligonucleotides, which corresponded to the T7 promoter consensus and contained activated phosphate groups at position +1, +2, or -14 relative to the transcription start. To obtain reactive groups, terminal phosphates were modified with N-oxybenzotriazole (HOBT), and internucleotide phosphates were repalced with a trisubstituted pyrophosphate (TSP). The resulting derivatives produced covalent complexes with T7 Pol. Covalent bonding involved His in the case of TSP at position +1 or HOBT at position +1 or -14, and Lys in the case of TSB at position -14.

  15. Arabidopsis WRKY45 transcription factor activates PHOSPHATE TRANSPORTER1;1 expression in response to phosphate starvation.

    PubMed

    Wang, Hui; Xu, Qian; Kong, You-Han; Chen, Yun; Duan, Jun-Ye; Wu, Wei-Hua; Chen, Yi-Fang

    2014-04-01

    The WRKY transcription factor family has more than 70 members in the Arabidopsis (Arabidopsis thaliana) genome, and some of them are involved in plant responses to biotic and abiotic stresses. This study evaluated the role of WRKY45 in regulating phosphate (Pi) uptake in Arabidopsis. WRKY45 was localized in the nucleus and mainly expressed in roots. During Pi starvation, WRKY45 expression was markedly induced, typically in roots. WRKY45 overexpression in Arabidopsis increased Pi content and uptake, while RNA interference suppression of WRKY45 decreased Pi content and uptake. Furthermore, the WRKY45-overexpressing lines were more sensitive to arsenate, the analog of Pi, compared with wild-type seedlings. These results indicate that WRKY45 positively regulates Arabidopsis Pi uptake. Quantitative real-time polymerase chain reaction and β-glucuronidase staining assays showed that PHOSPHATE TRANSPORTER1;1 (PHT1;1) expression was enhanced in the WRKY45-overexpressing lines and slightly repressed in the WRKY45 RNA interference line. Chromatin immunoprecipitation and electrophoretic mobility shift assay results indicated that WRKY45 can bind to two W-boxes within the PHT1;1 promoter, confirming the role of WRKY45 in directly up-regulating PHT1;1 expression. The pht1;1 mutant showed decreased Pi content and uptake, and overexpression of PHT1;1 resulted in enhanced Pi content and uptake. Furthermore, the PHT1;1-overexpressing line was much more sensitive to arsenate than WRKY45-overexpressing and wild-type seedlings, indicating that PHT1;1 overexpression can enhance Arabidopsis Pi uptake. Moreover, the enhanced Pi uptake and the increased arsenate sensitivity of the WRKY45-overexpressing line was impaired by pht1;1 (35S:WRKY45-18::pht1;1), demonstrating an epistatic genetic regulation between WRKY45 and PHT1;1. Together, our results demonstrate that WRKY45 is involved in Arabidopsis response to Pi starvation by direct up-regulation of PHT1;1 expression.

  16. Synthesis and evaluation of chromogenic and fluorogenic substrates for high-throughput detection of enzymes that hydrolyze inorganic polyphosphate.

    PubMed

    Hebbard, Carleigh F F; Wang, Yan; Baker, Catherine J; Morrissey, James H

    2014-08-11

    Inorganic polyphosphates, linear polymers of orthophosphate, occur naturally throughout biology and have many industrial applications. Their biodegradable nature makes them attractive for a multitude of uses, and it would be important to understand how polyphosphates are turned over enzymatically. Studies of inorganic polyphosphatases are, however, hampered by the lack of high-throughput methods for detecting and quantifying rates of polyphosphate degradation. We now report chromogenic and fluorogenic polyphosphate substrates that permit spectrophotometric monitoring of polyphosphate hydrolysis and allow for high-throughput analyses of both endopolyphosphatase and exopolyphosphatase activities, depending on assay configuration. These substrates contain 4-nitrophenol or 4-methylumbelliferone moieties that are covalently attached to the terminal phosphates of polyphosphate via phosphoester linkages formed during reactions mediated by EDAC (1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide). This report identifies Nudt2 as an inorganic polyphosphatase and also adds to the known coupling chemistry for polyphosphates, permitting facile covalent linkage of alcohols with the terminal phosphates of inorganic polyphosphate.

  17. Chromium liquid waste inertization in an inorganic alkali activated matrix: leaching and NMR multinuclear approach.

    PubMed

    Ponzoni, Chiara; Lancellotti, Isabella; Barbieri, Luisa; Spinella, Alberto; Saladino, Maria Luisa; Martino, Delia Chillura; Caponetti, Eugenio; Armetta, Francesco; Leonelli, Cristina

    2015-04-09

    A class of inorganic binders, also known as geopolymers, can be obtained by alkali activation of aluminosilicate powders at room temperature. The process is affected by many parameters (curing time, curing temperature, relative humidity etc.) and leads to a resistant matrix usable for inertization of hazardous waste. In this study an industrial liquid waste containing a high amount of chromium (≈ 2.3 wt%) in the form of metalorganic salts is inertized into a metakaolin based geopolymer matrix. One of the innovative aspects is the exploitation of the water contained in the waste for the geopolymerization process. This avoided any drying treatment, a common step in the management of liquid hazardous waste. The evolution of the process--from the precursor dissolution to the final geopolymer matrix hardening--of different geopolymers containing a waste amount ranging from 3 to 20%wt and their capability to inertize chromium cations were studied by: i) the leaching tests, according to the EN 12,457 regulation, at different curing times (15, 28, 90 and 540 days) monitoring releases of chromium ions (Cr(III) and Cr(VI)) and the cations constituting the aluminosilicate matrix (Na, Si, Al); ii) the humidity variation for different curing times (15 and 540 days); iii) SEM characterization at different curing times (28 and 540 days); iv) the trend of the solution conductivity and pH during the leaching test; v) the characterization of the short-range ordering in terms of TOT bonds (where T is Al or Si) by (29)Si and (27)Al solid state magic-angle spinning nuclear magnetic resonance (ss MAS NMR) for geopolymers containing high amounts of waste (10-20%wt). The results show the formation of a stable matrix after only 15 days independently on the waste amount introduced; the longer curing times increase the matrices stabilities and their ability to immobilize chromium cations. The maximum amount of waste that can be inertized is around 10 wt% after a curing time of 28 days.

  18. Phosphate glass core/silica clad fibres with a high concentration of active rare-earth ions

    NASA Astrophysics Data System (ADS)

    Egorova, O. N.; Galagan, B. I.; Denker, B. I.; Sverchkov, S. E.; Semjonov, S. L.

    2016-12-01

    We report a study of silica-clad composite optical fibres having a phosphate glass core doped with active rare-earth elements. The phosphate glass core allows a high concentration of active rare-earth ions to be obtained, and the silica cladding ensures high mechanical strength and facilitates fusion splicing of such fibres to silica fibres. Owing to the high concentration of active rare-earth ions, this type of fibre is potentially attractive for applications where a small cavity length and high lasing efficiency are needed.

  19. Dietary phosphorus regulates intestinal transport and plasma concentrations of phosphate in rainbow trout.

    PubMed

    Avila, E M; Tu, H; Basantes, S; Ferraris, R P

    2000-05-01

    Intestinal inorganic phosphate transport and its regulation have not been studied in fish. In this study, we initially characterized the mechanisms of intestinal inorganic phosphate transport in rainbow trout (Oncorhynchus mykiss) then determined the effects of dietary phosphorus concentrations on intestinal inorganic phosphate uptake, plasma inorganic phosphate, and intestinal luminal inorganic phosphate concentrations. In 11-g trout, the saturable mechanism of brushborder inorganic phosphate uptake had a Kt= 1.2 mmol l(-1) and a Vmax = 0.22 nmol mg(-1) min(-1), while the diffusive component had a Kd = 0.012 min(-1). Similar kinetic constants were obtained from 51-g trout, suggesting that development or size had little effect on transport. Tracer inorganic phosphate (1.18 mmol l(-1)) uptake was almost completely inhibited (>95%) by 20 mmol l(-1) unlabeled inorganic phosphate. Inorganic phosphate uptake (0.2 mmol l(-1)) was strongly inhibited (approximately 75% inhibition) by phosphonoformic acid, a competitive inhibitor of mammalian inorganic phosphate transport, as well as by the absence of Na+ (approximately 90% inhibition). Northern blot and reverse transcription-polymerase chain reaction indicated that the intestinal inorganic phosphate transporter in trout is not related to the cloned Na+ inorganic phosphate-II transporter of winter flounder. Intestinal luminal and plasma inorganic phosphate concentrations each increased with dietary P concentrations. Intestinal inorganic phosphate, but not proline, absorption rates decreased with dietary phosphorus concentrations. As in mammals and birds, a Na-dependent inorganic phosphate carrier that is tightly regulated by diet is present in trout small intestine.

  20. Efficacy of flowable gel-type EDTA at removing the smear layer and inorganic debris under manual dynamic activation.

    PubMed

    Kim, Hee-Jin; Park, Su-Jung; Park, Sang-Hyuk; Hwang, Yun-Chan; Yu, Mi-Kyung; Min, Kyung-San

    2013-07-01

    A flowable gel-type EDTA solution containing urea peroxide and polyacrylic acid was recently introduced into the endodontic market. However, its efficacy for removing the smear layer and inorganic debris remains unknown. This study was performed to investigate the relative efficacies of the flowable gel-type and liquid-type EDTA solutions for removal of the smear layer and inorganic debris. We also evaluated the effects of manual dynamic activation (MDA). Wettability was evaluated by measuring the contact angle. The incidence of accidental extrusion of irrigant was determined. The effervescent effect was evaluated by mixing the solutions with sodium hypochlorite. The efficacies of the EDTA solutions at removing the smear layer and inorganic debris were evaluated by scanning electron microscopic examination. The contact angles of the 2 EDTA solutions did not differ significantly throughout the experiment (P > .05). Accidental extrusion occurred 4 times for the liquid-type EDTA but never for the gel-type EDTA. The gel-type but not the liquid-type EDTA showed an effervescent effect. The EDTA/MDA treatment combinations did not produce significantly different smear layer scores (P > .05). However, the debris scores for the coronal and middle parts were significantly lower for the gel-type EDTA with MDA than for the liquid-type EDTA without MDA (P < .05). Our results suggest that the newly introduced gel-type EDTA might be an acceptable irrigant for removing the smear layer and inorganic debris present on the root canal wall. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  1. Cytocompatibility and osteogenic activity of a novel calcium phosphate silicate bioceramic: Silicocarnotite.

    PubMed

    Duan, Wei; Ning, Congqin; Tang, Tingting

    2013-07-01

    In the present study, the effect of a novel bioceramic, silicon-containing calcium phosphate ceramic (silicocarnotite, Ca5 (PO4 )2 SiO4 , CPS) on attachment, proliferation, and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBMSC) has been investigated in comparison to hydroxyapatite (HA). The CPS showed a similar cell attachment behavior to HA, while the proliferation of rBMSC on CPS was significantly higher than that on HA, which indicated that CPS had a good cytocompatibility. Moreover, the expression of alkaline phosphatase activity and osteogenic-related genes, including Runx-2, osteopontin (OPN), bone sialoprotein (BSP) and osteocalcin (OC), demonstrated that CPS enhanced the osteogenic differentiation of rBMSC and accelerated the differentiation process. The results suggest that CPS ceramic exhibits a good cytocompatibility and osteogenic activity, which might be used as a potential candidate material for bone tissue engineering.

  2. A rapid and simple method for estimating sulfate reduction activity and quantifying inorganic sulfides

    USGS Publications Warehouse

    Ulrich, G.A.; Krumholz, L.R.; Suflita, J.M.

    1997-01-01

    A simplified passive extraction procedure for quantifying reduced inorganic sulfur compounds from sediments and water is presented. This method may also be used for the estimation of sulfate reduction rates. Efficient extraction of FeS, FeS(inf2), and S(sup2-) was obtained with this procedure; however, the efficiency for S(sup0) depended on the form that was tested. Passive extraction can be used with samples containing up to 20 mg of reduced sulfur. We demonstrated the utility of this technique in a determination of both sulfate reduction rates and reduced inorganic sulfur pools in marine and freshwater sediments. A side-by-side comparison of the passive extraction method with the established single-step distillation technique yielded comparable results with a fraction of the effort.

  3. Deletion of hexose-6-phosphate dehydrogenase activates the unfolded protein response pathway and induces skeletal myopathy.

    PubMed

    Lavery, Gareth G; Walker, Elizabeth A; Turan, Nil; Rogoff, Daniela; Ryder, Jeffery W; Shelton, John M; Richardson, James A; Falciani, Francesco; White, Perrin C; Stewart, Paul M; Parker, Keith L; McMillan, Daniel R

    2008-03-28

    Hexose-6-phosphate dehydrogenase (H6PD) is the initial component of a pentose phosphate pathway inside the endoplasmic reticulum (ER) that generates NADPH for ER enzymes. In liver H6PD is required for the 11-oxoreductase activity of 11beta-hydroxysteroid dehydrogenase type 1, which converts inactive 11-oxo-glucocorticoids to their active 11-hydroxyl counterparts; consequently, H6PD null mice are relatively insensitive to glucocorticoids, exhibiting fasting hypoglycemia, increased insulin sensitivity despite elevated circulating levels of corticosterone, and increased basal and insulin-stimulated glucose uptake in muscles normally enriched in type II (fast) fibers, which have increased glycogen content. Here, we show that H6PD null mice develop a severe skeletal myopathy characterized by switching of type II to type I (slow) fibers. Running wheel activity and electrically stimulated force generation in isolated skeletal muscle are both markedly reduced. Affected muscles have normal sarcomeric structure at the electron microscopy level but contain large intrafibrillar membranous vacuoles and abnormal triads indicative of defects in structure and function of the sarcoplasmic reticulum (SR). SR proteins involved in calcium metabolism, including the sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA), calreticulin, and calsequestrin, show dysregulated expression. Microarray analysis and real-time PCR demonstrate overexpression of genes encoding proteins in the unfolded protein response pathway. We propose that the absence of H6PD induces a progressive myopathy by altering the SR redox state, thereby impairing protein folding and activating the unfolded protein response pathway. These studies thus define a novel metabolic pathway that links ER stress to skeletal muscle integrity and function.

  4. Chloroplast Activity and 3'phosphadenosine 5'phosphate Signaling Regulate Programmed Cell Death in Arabidopsis.

    PubMed

    Bruggeman, Quentin; Mazubert, Christelle; Prunier, Florence; Lugan, Raphaël; Chan, Kai Xun; Phua, Su Yin; Pogson, Barry James; Krieger-Liszkay, Anja; Delarue, Marianne; Benhamed, Moussa; Bergounioux, Catherine; Raynaud, Cécile

    2016-03-01

    Programmed cell death (PCD) is a crucial process both for plant development and responses to biotic and abiotic stress. There is accumulating evidence that chloroplasts may play a central role during plant PCD as for mitochondria in animal cells, but it is still unclear whether they participate in PCD onset, execution, or both. To tackle this question, we have analyzed the contribution of chloroplast function to the cell death phenotype of the myoinositol phosphate synthase1 (mips1) mutant that forms spontaneous lesions in a light-dependent manner. We show that photosynthetically active chloroplasts are required for PCD to occur in mips1, but this process is independent of the redox state of the chloroplast. Systematic genetic analyses with retrograde signaling mutants reveal that 3'-phosphoadenosine 5'-phosphate, a chloroplast retrograde signal that modulates nuclear gene expression in response to stress, can inhibit cell death and compromises plant innate immunity via inhibition of the RNA-processing 5'-3' exoribonucleases. Our results provide evidence for the role of chloroplast-derived signal and RNA metabolism in the control of cell death and biotic stress response. © 2016 American Society of Plant Biologists. All Rights Reserved.

  5. Adsorption between TC-stabilized AuNPs and the phosphate group: application of the PTP1B activity assay.

    PubMed

    Lv, Jun; Wang, Xiaonan; Zhang, Yuanyuan; Li, Defeng; Zhang, Juan; Sun, Lizhou

    2015-12-07

    Based on the adsorption between tetracycline (TC) and phosphate groups, a general colorimetric method is explored in this work by using TC-stabilized gold nanoparticles (TC/AuNPs) and 4-aminophenyl phosphate-functionalized Fe3O4 magnetic nanoparticles (APP/MNPs). Taking protein tyrosine phosphatase 1B (PTP1B) as an example, 4-aminophenyl phosphate (APP) can be hydrolyzed into 4-aminophenol (AP) by PTP1B, resulting in the disappearance of the phosphate group on the outer layer of MNPs and the loss of corresponding adsorptive ability. Upon addition of TC/AuNP solution, TC/AuNPs will remain in the supernatant solution after magnetic separation and a high absorbance value can be observed. So PTP1B activity is related to the concentrations of TC/AuNPs in the supernatant solution. In this work, the enzyme activity can be determined at levels as low as 0.0885 U mL(-1) and over a linear detection range as wide as 0.1 U mL(-1) to 0.9 U mL(-1). Moreover, using the proposed method, the inhibition effect of betulinic acid (BA) and sodium orthovanadate (Na3VO4) on PTP1B activity can be tested with IC50 values of 30 μM and 4 μM, respectively. Therefore, a universal platform for the accurate colorimetric analysis of kinase and phosphatase activities can be established through the adsorption between TC and phosphate groups.

  6. Soil application of dinitroaniline and arylphenoxy propionic herbicides influences the activities of phosphate-solubilizing microorganisms in soil.

    PubMed

    Das, Amal Chandra; Nayek, Hemanta; Chakravarty, Arunabha

    2012-12-01

    An experiment was conducted under laboratory conditions to investigate the effect of two systemic herbicides, viz. pendimethalin (a dinitroaniline) and quizalofop (an arylphenoxy propionic acid) at their recommended field application rates (1.0 kg and 50 g active ingredient per hectare, respectively), either separately or in a combination, on growth and activities of phosphate-solubilizing microorganisms in relation to their effects on biochemical transformations and availability of organic carbon, total and available phosphorus in a Typic Haplustept soil of West Bengal, India. Application of herbicides, in general, significantly stimulated the growth and activities of phosphate-solubilizing microorganisms which increased microbial biomass resulting in higher accumulation of oxidizable organic carbon, total and available phosphorus in soil as compared to untreated control. The combined application of both the herbicides highly stimulated the proliferations of phosphate-solubilizing microorganisms, while pendimethalin alone significantly accentuated phosphate-solubilizing capacities 36.4% as compared to untreated control and retained highest amount of total phosphorus due to greater microbial activities in soil. The separate application of quizalofop also manifested an induced effect on the proliferations of phosphate-solubilizing microorganisms and accounted significant amounts of organic carbon and available phosphorus in the soil system. The results of the present study thus indicated that the cited herbicides at their field application rates can be safely used to eradicate weeds in the crop fields.

  7. FTY720 Phosphate Activates Sphingosine-1-Phosphate Receptor 2 and Selectively Couples to Gα12/13/Rho/ROCK to Induce Myofibroblast Contraction.

    PubMed

    Sobel, Katrin; Monnier, Lucile; Menyhart, Katalin; Bolinger, Matthias; Studer, Rolf; Nayler, Oliver; Gatfield, John

    2015-06-01

    FTY720 phosphate (FTY720-P; 2-amino-2-[2-(4-octylphenyl)ethyl]-1,3-propanediol, monodihydrogen phosphate ester) is a nonselective sphingosine-1-phosphate (S1P) receptor agonist thought to be devoid of activity at the S1P2 receptor subtype. However, we have recently shown that FTY720-P displays significant S1P2 receptor agonist activity in recombinant cells and fibroblasts expressing endogenous S1P2 receptors. To elucidate the S1P2-dependent signaling pathways that were activated by FTY720-P, we employed second messenger assays and impedance-based assays in combination with pharmacological and small interfering RNA-based pathway inhibition in recombinant Chinese hamster ovary (CHO)-S1P2 cells as well as human lung myofibroblasts generated in vitro. In CHO-S1P2 cells, FTY720-P did not modulate cAMP or calcium levels. However, reporter-gene assays, impedance-based assays with a selective Rho-associated kinase (ROCK) inhibitor, Gα12/13 knockdown and activated Rho-pull-down assays demonstrated that FTY720-P potently activated Gα12/13/Rho/ROCK signaling. S1P similarly activated Gα12/13/Rho/ROCK signaling via S1P2 receptors, whereas the two selective S1P1 receptor agonists (Z,Z)-5-(3-chloro-4-[(2R)-2,3-dihydroxy-propoxy]-benzylidene)-2-propylimino-3-o-tolyl-thiazolidin-4-one (ponesimond) and 5-[4-phenyl-5-(trifluoromethyl)thiophen-2-yl]-3-[3-(trifluoromethyl)phenyl]1,2,4-oxadiazole (SEW2871) were inactive. In lung myofibroblasts, which mainly expressed the S1P2 receptor subtype, we showed that FTY720-P selectively activated the Gα12/13/Rho/ROCK pathway via the S1P2 receptor. Moreover, the activation of the Gα12/13/Rho/ROCK pathway in myofibroblasts by FTY720-P caused potent myofibroblast contraction similar to that induced by the natural ligand S1P. Thus, complementing second messenger assays with unbiased label-free assays or phenotypic assays in native expression systems can uncover activation of additional pathways, such as Gα12/13/Rho/ROCK signaling.

  8. Effect of pH, ionic strength, and temperature on the phosphate adsorption onto lanthanum-doped activated carbon fiber.

    PubMed

    Liu, Jianyong; Wan, Lihua; Zhang, Ling; Zhou, Qi

    2011-12-15

    Phosphate removal from polluted water is crucial to preventing eutrophication. Herein, we present the investigation on phosphate adsorption in aqueous solutions by using lanthanum-doped activated carbon fiber (ACF-La). Various batch sorption conditions, e.g., pH, ionic strength, and temperature were tested, and the adsorption mechanisms were discussed. The sorption capacity of ACF-La was higher in acidic solutions than that in basic ones, suggesting that the Lewis acid-base interaction gradually dominated the adsorption process with the increase in pH values. The degree of phosphate removal decreased with the enhancement of the ionic strength of the solution, meaning that the adsorption of phosphate on ACF-La was strongly dependent on ionic strength. Employing the pseudo first- and second-order, and intra-particle diffusion models to evaluate the adsorption kinetics of phosphate onto ACF-La indicated that the second-order model best fits the experimental data. The presence of chloride ion in solutions increased the effect of intra-particle diffusion on the adsorption of phosphate onto ACF-La but reduced the overall rate of the adsorption. The thermodynamic parameters were determined which revealed the feasibility, spontaneity, and endothermic nature of adsorption. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Effect of chronologic age on induction of cystathionine synthase, uroporphyrinogen I synthase, and glucose-6-phosphate dehydrogenase activities in lymphocytes.

    PubMed Central

    Gartler, S M; Hornung, S K; Motulsky, A G

    1981-01-01

    The activities of cystathionine synthase [L-serine hydro-lyase (adding homocysteine), EC 4.2.1.22], uroporphyrinogen I synthase [porphobilinogen ammonia-lyase (polymerizing), EC 4.3.1.8], and glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NADP+ 1-oxidoreductase, EC 1.1.1.49) have been measured in phytohemagglutinin-stimulated lymphocytes of young and old human subjects. A significant decrease in activity with age was observed for cystathionine synthase and uroporphyrinogen I synthase but not for glucose-6-phosphate dehydrogenase. These changes could not be related to declining phytohemagglutinin response with aging. Age-related decreases in activity of some enzymes may be relevant for an understanding of the biology of aging. False assignment of heterozygosity, and even homozygosity, for certain genetic disorders, such as homocystinuria, may result when low enzyme levels are detected in the lymphocytes of older people. PMID:6940198

  10. Soil to plant transfer of alpha activity in potato plants: impact of phosphate fertilizers.

    PubMed

    Chauhan, Rishi Pal; Kumar, Amit

    2015-01-01

    Radionuclides in the phosphate fertilizers belonging to (232)Th and (238)U and (40) K are the major contributors to the outdoor terrestrial natural radiation. These radionuclides are transferred from fertilizer to food through soil. Present work deals with the alpha activity in the different parts of the potato (Solanum Tuberosum) plants grown under controlled pots experiment using different amounts of phosphate fertilizers and urea. Alpha activities have been measured by track etch technique using the solid-state nuclear track detectors (LR-115). Translocation factor for the fruit (edible Part) varied from 0.13 (for DAP) to 0.73 (for PF) with an average of 0.40 ± 0.26 for the plant grown with 20 g of fertilizers. Translocation factors increased with the increase in amount of fertilizers having value 0.51 ± 0.31 for the plant grown with 50 g of fertilizers. The translocation factor for the lower and the upper part of leaves varied from 0.44 to 0.67 and 0.22 to 0.83 with an average value 0.55 ± 0.15 and 0.45 ± 0.23 respectively. The transfer factor (TF's) for the potato plants varied from 1.5 × 10(-2) to 1.03 × 10(-1) for root, from 1.3 × 10(-2) to 1.23 × 10(-1) for stem, from 2.1 × 10(-3) to 4.5 × 10(-2) for fruit and from 5.4 × 10(-3) to 5.8 × 10(-3) for lower part of the leaves after 105 days of the plantation. The results revealed that the alpha activity in the potato plants was higher in case of the plants grown with the use of phosphate fertilizers than with other fertilizers.

  11. Impact of organic and inorganic fertilizers application on the phytochemical and antioxidant activity of Kacip Fatimah (Labisia pumila Benth).

    PubMed

    Ibrahim, Mohd Hafiz; Jaafar, Hawa Z E; Karimi, Ehsan; Ghasemzadeh, Ali

    2013-09-05

    A study was conducted to compare secondary metabolites and antioxidant activity of Labisia pumila Benth (Kacip Fatimah) in response to two sources of fertilizer [i.e., organic (chicken dung; 10% N:10% P₂O₅:10% K₂O) and inorganic fertilizer (NPK green; 15% N, 15% P₂O₅, 15% K₂O)] under different N rates of 0, 90, 180 and 270 kg N/ha. The experiment was arranged in a randomized complete block design replicated three times. At the end of 15 weeks, it was observed that the application of organic fertilizer enhanced the production of total phenolics, flavonoids, ascorbic acid, saponin and gluthathione content in L. pumila, compared to the use of inorganic fertilizer. The nitrate content was also reduced under organic fertilization. The application of nitrogen at 90 kg N/ha improved the production of secondary metabolites in Labisia pumila. Higher rates in excess of 90 kg N/ha reduced the level of secondary metabolites and antioxidant activity of this herb. The DPPH and FRAP activity was also highest at 90 kg N/ha. The results indicated that the use of chicken dung can enhance the production of secondary metabolites and improve antioxidant activity of this herb.

  12. Antibacterial activity of plastics coated with silver-doped organic-inorganic hybrid coatings prepared by sol-gel processes.

    PubMed

    Marini, M; De Niederhausern, S; Iseppi, R; Bondi, M; Sabia, C; Toselli, M; Pilati, F

    2007-04-01

    Silver-doped organic-inorganic hybrid coatings were prepared starting from tetraethoxysilane- and triethoxysilane-terminated poly(ethylene glycol)-block-polyethylene by the sol-gel process. They were applied as a thin layer (0.6-1.1 microm) to polyethylene (PE) and poly(vinyl chloride) (PVC) films and the antibacterial activity of the coated films was tested against Gram-negative (Escherichia coli ATCC 25922) and Gram-positive (Staphylococcus aureus ATCC 6538) bacteria. The effect of several factors (such as organic-inorganic ratio, type of catalyst, time of post-curing, silver ion concentration, etc.) was investigated. Measurements at different contact times showed a rapid decrease of the viable count for both tested strains. The highest antibacterial activity [more than 6 log reduction within 6 h starting from 106 colony-forming units (cfu) mL-1] was obtained for samples with an organic-inorganic weight ratio of 80:20 and 5 wt % silver salt with respect to the coating. For the coatings prepared by an acid-catalyzed process, a high level of permanence of the antibacterial activity of the coated films was demonstrated by repeatedly washing the samples in warm water or by immersion in physiological saline solution at 37 degrees C for 3 days. The release of silver ions per square meter of coating is very similar to that previously observed for polyamides filled with metallic silver nanoparticles; however, when compared on the basis of Ag content, the concentration of silver ions released from the coating is much higher than that released from 1 mm thick specimens of polyamide (PA) filled with silver nanoparticles. Transparency and good adhesion of the coating to PE and PVC plastic substrates without any previous surface treatment are further interesting features.

  13. Studies on cartilage formation XXL Activity of enzymes belonging to the pentose-phosphate cycle in the regenerating articular surface.

    PubMed

    Oláh, E H; Hadházy, C; Glant, T

    1979-01-01

    The distal articular surface of the femur was removed operatively in 36 dogs. In the regenerating chondrifying articular surface and in the granulation tissue adhering to the capsule glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities were determined 7, 33 and 70 days after operation. In both tissues the activity of these enzymes characteristic of the pentose phosphate cycle ws the highest in the early postoperative stage. This initial increase in activity was followed by a marked reduction in the regenerating articular surface and by a moderate decrease in the tissue adhering to the capsule. For the loss in activity occurring in the chondrifying articular surface, the connective tissue cells (fibroblasts) are responsible. Cartilage precursors and young chondrocytes show a high glucose-6-phosphate dehydrogenase and 6-phosphogluconate activity. Presumably, in the given case of the functions of the pentose-phosphate cycle the NADPH generation and supply of building stones prevail. The activity of these enzymes ws determined in the articular cartilage and in the synovial membrane of the knee joint in further 18 dogs. The activity in the articular cartilage was very slight as compared to that in the synovial membrane.

  14. Antibacterial and photocatalytic activity of TiO2 and ZnO nanomaterials in phosphate buffer and saline solution.

    PubMed

    Ng, Alan Man Ching; Chan, Charis May Ngor; Guo, Mu Yao; Leung, Yu Hang; Djurišić, Aleksandra B; Hu, Xu; Chan, Wai Kin; Leung, Frederick Chi Chung; Tong, Shuk Yin

    2013-06-01

    We studied antibacterial and photocatalytic activity of anatase TiO2 and ZnO in phosphate buffer and saline solution. We found that the different anions in the suspension medium (chloride and phosphate) significantly affected the following suspension properties: the stability of nanoparticle suspension, the release of metal ions from the nanoparticles, and the production of the reactive oxygen species by the nanoparticles. As a result, antibacterial activity and photocatalytic dye degradation were also affected. However, the effect of the suspension medium was different for ZnO and TiO2. Obtained results are discussed.

  15. Elucidation of the inorganic chemistry of hydrotreating catalysts

    SciTech Connect

    DeCanio, E.C.; Edwards, J.C.; Storm, D.A.; Bruno, J.W.

    1993-12-31

    New environmental regulations are making it necessary to developed improved hydrotreating catalysts for the removal of sulfur, nitrogen and aromatics from refinery streams. In order to develop better catalysts, the authors must gain a more detailed understanding of the inorganic chemistry of these catalysts. Commercial catalysts typically contain ca. 15 wt% molybdenum or tungsten oxides and ca. 4 wt% nickel or cobalt. Additives, such as phosphate and fluoride, are often added to improve the catalytic activity. However, the role of these additives is not fully understood. The authors have, therefore, carried out studies on alumina supported phosphate and flouride materials using FT-IR, powder x-ray diffraction, and solid-state NMR ({sup 31}P, {sup 27}Al, and {sup 1}H). The results of this work have enabled the authors to determine the structures of the various compounds formed on the alumina system when fluoride or phosphate is present.

  16. Lipid phosphate phosphatase activity regulates dispersal and bilateral sorting of embryonic germ cells in Drosophila

    PubMed Central

    Renault, Andrew D.; Kunwar, Prabhat S.; Lehmann, Ruth

    2010-01-01

    In Drosophila, germ cell survival and directionality of migration are controlled by two lipid phosphate phosphatases (LPP), wunen (wun) and wunen-2 (wun2). wun wun2 double mutant analysis reveals that the two genes, hereafter collectively called wunens, act redundantly in primordial germ cells. We find that wunens mediate germ cell-germ cell repulsion and that this repulsion is necessary for germ cell dispersal and proper transepithelial migration at the onset of migration and for the equal sorting of the germ cells between the two embryonic gonads during their migration. We propose that this dispersal function optimizes adult fecundity by assuring maximal germ cell occupancy of both gonads. Furthermore, we find that the requirement for wunens in germ cell survival can be eliminated by blocking germ cell migration. We suggest that this essential function of Wunen is needed to maintain cell integrity in actively migrating germ cells. PMID:20431117

  17. Induction of an Extracellular Cyclic Nucleotide Phosphodiesterase as an Accessory Ribonucleolytic Activity during Phosphate Starvation of Cultured Tomato Cells

    PubMed Central

    Abel, Steffen; Nürnberger, Thorsten; Ahnert, Volker; Krauss, Gerd-Joachim; Glund, Konrad

    2000-01-01

    During growth under conditions of phosphate limitation, suspension-cultured cells of tomato (Lycopersicon esculentum Mill.) secrete phosphodiesterase activity in a similar fashion to phosphate starvation-inducible ribonuclease (RNase LE), a cyclizing endoribonuclease that generates 2′:3′-cyclic nucleoside monophosphates (NMP) as its major monomeric products (T. Nürnberger, S. Abel, W. Jost, K. Glund [1990] Plant Physiol 92: 970–976). Tomato extracellular phosphodiesterase was purified to homogeneity from the spent culture medium of phosphate-starved cells and was characterized as a cyclic nucleotide phosphodiesterase. The purified enzyme has a molecular mass of 70 kD, a pH optimum of 6.2, and an isoelectric point of 8.1. The phosphodiesterase preparation is free of any detectable deoxyribonuclease, ribonuclease, and nucleotidase activity. Tomato extracellular phosphodiesterase is insensitive to EDTA and hydrolyzes with no apparent base specificity 2′:3′-cyclic NMP to 3′-NMP and the 3′:5′-cyclic isomers to a mixture of 3′-NMP and 5′-NMP. Specific activities of the enzyme are 2-fold higher for 2′:3′-cyclic NMP than for 3′:5′-cyclic isomers. Analysis of monomeric products of sequential RNA hydrolysis with purified RNase LE, purified extracellular phosphodiesterase, and cleared −Pi culture medium as a source of 3′-nucleotidase activity indicates that cyclic nucleotide phosphodiesterase functions as an accessory ribonucleolytic activity that effectively hydrolyzes primary products of RNase LE to substrates for phosphate-starvation-inducible phosphomonoesterases. Biosynthetical labeling of cyclic nucleotide phopshodiesterase upon phosphate starvation suggests de novo synthesis and secretion of a set of nucleolytic enzymes for scavenging phosphate from extracellular RNA substrates. PMID:10677447

  18. Epidermal growth factor-induced cellular invasion requires sphingosine-1-phosphate/sphingosine-1-phosphate 2 receptor-mediated ezrin activation

    PubMed Central

    Orr Gandy, K. Alexa; Adada, Mohamad; Canals, Daniel; Carroll, Brittany; Roddy, Patrick; Hannun, Yusuf A.; Obeid, Lina M.

    2013-01-01

    Ezrin, radixin, and moesin (ERM) proteins link cortical actin to the plasma membrane and coordinate cellular events that require cytoskeletal rearrangement, including cell division, migration, and invasion. While ERM proteins are involved in many important cellular events, the mechanisms regulating their function are not completely understood. Our laboratory previously identified reciprocal roles for the sphingolipids ceramide and sphingosine-1-phosphate (S1P) in the regulation of ERM proteins. We recently showed that ceramide-induced activation of PP1α leads to dephosphorylation and inactivation of ERM proteins, while S1P results in phosphorylation and activation of ERM proteins. Following these findings, we aimed to examine known inducers of the SK/S1P pathway and evaluate their ability to regulate ERM proteins. We examined EGF, a known inducer of the SK/S1P pathway, for its ability to regulate the ERM family of proteins. We found that EGF induces ERM c-terminal threonine phosphorylation via activation of the SK/S1P pathway, as this was prevented by siRNA knockdown or pharmacological inhibition of SK. Using pharmacological, as well as genetic, knockdown approaches, we determined that EGF induces ERM phosphorylation via activation of S1PR2. In addition, EGF led to cell polarization in the form of lamellipodia, and this occurred through a mechanism involving S1PR2-mediated phosphorylation of ezrin T567. EGF-induced cellular invasion was also found to be dependent on S1PR2-induced T567 ezrin phosphorylation, such that S1PR2 antagonist, JTE-013, and expression of a dominant-negative ezrin mutant prevented cellular invasion toward EGF. In this work, a novel mechanism of EGF-stimulated invasion is unveiled, whereby S1P-mediated activation of S1PR2 and phosphorylation of ezrin T567 is required.—Orr Gandy, K. A., Adada, M., Canals, D., Carroll, B., Roddy, P., Hannun, Y. A., Obeid, L. M. Epidermal growth factor-induced cellular invasion requires sphingosine-1-phosphate

  19. Diel activity of sucrose phosphate synthase in rice. [Oryza sativa L

    SciTech Connect

    Hussain, M.W.; Bowes, G.; Rowland-Bamford, A.J.; Allen, L.H. )

    1991-05-01

    Rice (Oryza sativa L.) was grown in growth chambers at 28/23C day/night temperatures with 16-h photoperiod at 600 umol m{sup {minus}2} s{sup {minus}1}. Diel sucrose phosphate synthase (SPS) activity, at 21 days after planting, was measured at saturating substrate concentrations. Data suggests that SPS activity increased during illumination to a maximum of 0.8 nmol mg{sup {minus}1} protein min{sup {minus}1} after 5h. Throughout the remainder of the light period there was a slow decline in activity. Upon darkening, activity further declined to 0.4 nmol mg{sup {minus}1} protein min{sup {minus}1}, a basal level that was maintained throughout the night. It appears that rice SPS undergoes light/dark transitions, suggesting there may be two kinetic forms of SPS. Changes in SPS activity will be discussed in relation to kinetic studies, and also CO{sub 2} enrichment of rice during growth.

  20. Rev1 is a base excision repair enzyme with 5′-deoxyribose phosphate lyase activity

    PubMed Central

    Prasad, Rajendra; Poltoratsky, Vladimir; Hou, Esther W.; Wilson, Samuel H.

    2016-01-01

    Rev1 is a member of the Y-family of DNA polymerases and is known for its deoxycytidyl transferase activity that incorporates dCMP into DNA and its ability to function as a scaffold factor for other Y-family polymerases in translesion bypass events. Rev1 also is involved in mutagenic processes during somatic hypermutation of immunoglobulin genes. In light of the mutation pattern consistent with dCMP insertion observed earlier in mouse fibroblast cells treated with a base excision repair-inducing agent, we questioned whether Rev1 could also be involved in base excision repair (BER). Here, we uncovered a weak 5′-deoxyribose phosphate (5′-dRP) lyase activity in mouse Rev1 and demonstrated the enzyme can mediate BER in vitro. The full-length Rev1 protein and its catalytic core domain are similar in their ability to support BER in vitro. The dRP lyase activity in both of these proteins was confirmed by NaBH4 reduction of the Schiff base intermediate and kinetics studies. Limited proteolysis, mass spectrometry and deletion analysis localized the dRP lyase active site to the C-terminal segment of Rev1's catalytic core domain. These results suggest that Rev1 could serve as a backup polymerase in BER and could potentially contribute to AID-initiated antibody diversification through this activity. PMID:27683219

  1. Potassium ion-activated hydrolysis of p-nitrophenyl phosphate in pancreatic islet-cell membranes.

    PubMed Central

    Lernmark, A; Parman, A; Täljedal, I B

    1977-01-01

    Hydrolysis of p-nitrophenyl phosphate was measured in a fraction enriched in plasma membranes from pancreatic islets of non-inbred ob/ob mice. Hydrolysis was stimulated by K+ (10mM) in the pH range 5--10; a small peak of K+-induced activation was observed between pH7.5 and 8. Both the K+-induced activation and the hydrolysis in the absence of K+ were Mg2+-dependent; maximum activation was obtained with 10mM-K+ plus 5 mM-Mg2+. Rb+ was as effective an activator as K+. Ouabain was inhibitory, the effect being inversely related to the K+ concentration; 0.1--0.2mM-ouabain caused about 50% inhibition in the presence of 1 mM-K+, but had no demonstrable effect in the presence of 4--5mM-K+. The K+-stimulated activity was markedly inhibited by 0.1mM-ATP, 35--140 MM-Na+, or 0.01 mM-p-chloromercuribenzenesulphonic acid. Similarities to Rb+ accumulation suggest that catalysis of univalent cation flow in pancreatic beta-cells may be coupled to a phosphoryl-transfer reaction with ATP as natural substrate or regulator. PMID:20876

  2. Osteogenic activity of cyclodextrin-encapsulated doxycycline in a calcium phosphate PCL and PLGA composite.

    PubMed

    Trajano, V C C; Costa, K J R; Lanza, C R M; Sinisterra, R D; Cortés, M E

    2016-07-01

    Composites of biodegradable polymers and calcium phosphate are bioactive and flexible, and have been proposed for use in tissue engineering and bone regeneration. When associated with the broad-spectrum antibiotic doxycycline (DOX), they could favor antimicrobial action and enhance the action of osteogenic composites. Composites of polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), and a bioceramic of biphasic calcium phosphate Osteosynt® (BCP) were loaded with DOX encapsulated in β-cyclodextrin (βCD) and were evaluated for effects on osteoblastic cell cultures. The DOX/βCD composite was prepared with a double mixing method. Osteoblast viability was assessed with methyl tetrazolium (MTT) assays after 1day, 7day, and 14days of composite exposure; alkaline phosphatase (AP) activity and collagen production were evaluated after 7days and 14days, and mineral nodule formation after 14days. Composite structures were evaluated by scanning electron microscopy (SEM). Osteoblasts exposed to the composite containing 25μg/mL DOX/βCD had increased cell proliferation (p<0.05) compared to control osteoblast cultures at all experimental time points, reaching a maximum in the second week. AP activity and collagen secretion levels were also elevated in osteoblasts exposed to the DOX/βCD composite (p<0.05 vs. controls) and reached a maximum after 14days. These results were corroborated by Von Kossa test results, which showed strong formation of mineralization nodules during the same time period. SEM of the composite material revealed a surface topography with pore sizes suitable for growing osteoblasts. Together, these results suggest that osteoblasts are viable, proliferative, and osteogenic in the presence of a DOX/βCD-containing BCP ceramic composite.

  3. Comparison of phosphate estimating methods in the presence of phytic acid for the determination of phytase activity.

    PubMed

    Sanikommu, Suma; Pasupuleti, Mukesh; Vadalkonda, Lakshmipathi

    2014-01-01

    Phosphate released from phytic acid can be used as a measure of phytase activity. However, most of the phosphate estimation methods have not examined the interference or interaction of phytic acid in the assay. In this article, we report the kinetics and influence of unreduced phytic acid on phosphate estimation by three of the often-used methods for phytase estimation, the AOAC, Cooper-Gowing, and Fiske-Subbarow methods. Our results show that the AOAC method is most suitable to estimate the phytase activity in the presence of phytate in the medium. In the Fiske and Subbarow method, we noticed that the time factor plays a role in the interference of the phytic acid; especially the readings taken during the second hour of incubation are influenced by the presence of phytic acid. The method of Cooper and Gowing is labor-intensive and is prone to give error values at higher concentrations.

  4. Generally recognized as safe (GRAS) Lactococcus lactis strains associated with Lippia sidoides Cham. are able to solubilize/mineralize phosphate.

    PubMed

    de Lacerda, Jackeline Rossetti Mateus; da Silva, Thais Freitas; Vollú, Renata Estebanez; Marques, Joana Montezano; Seldin, Lucy

    2016-01-01

    Eight strains isolated from the stems of Lippia sidoides were identified as belonging to Lactococcus lactis, a bacterial species considered as "generally recognized as safe". Their capacity to solubilize/mineralize phosphate was tested in vitro with different inorganic and organic phosphorus (P) sources. All strains were able to solubilize calcium phosphate as an inorganic P source, and the best result was observed with strain 003.41 which solubilized 31 % of this P source. Rock phosphate, a mined rock containing high amounts of phosphate bearing minerals, was solubilized by five strains. When calcium phytate was the organic P source used, the majority of the strains tested showed phosphate mineralization activity. Moreover, all strains were able to solubilize/mineralize phosphate from poultry litter, a complex P source containing inorganic and predominantly organic P. The presence of genes coding for phytase and alkaline phosphatase was searched within the strains studied. However, only gene sequences related to alkaline phosphatase (phoA and phoD) could be detected in the majority of the strains (excepting strain 006.29) with identities varying from 67 to 88 %. These results demonstrate for the first time the potential of L. lactis strains for phosphate solubilization/mineralization activity using a broad spectrum of P sources; therefore, they are of great importance for the future development of more safe bioinoculants with possible beneficial effects for agriculture.

  5. Activation of the Nrf2 Pathway by Inorganic Arsenic in Human Hepatocytes and the Role of Transcriptional Repressor Bach1

    PubMed Central

    Liu, Dan; Duan, Xiaoxu; Dong, Dandan; Bai, Caijun; Li, Xin; Sun, Guifan; Li, Bing

    2013-01-01

    Previous studies have proved that the environmental toxicant, inorganic arsenic, activates nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in many different cell types. This study tried to explore the hepatic Nrf2 pathway upon arsenic treatment comprehensively, since liver is one of the major target organs of arsenical toxicity. Our results showed that inorganic arsenic significantly induced Nrf2 protein and mRNA expression in Chang human hepatocytes. We also observed a dose-dependent increase of antioxidant response element- (ARE-) luciferase activity. Both the mRNA and protein levels of NAD(P)H:quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1) were all upregulated dramatically. On the other hand, entry and accumulation of Nrf2 protein in the nucleus, while exportting the transcriptional repressor BTB and CNC homology 1 (Bach1) from nucleus to cytoplasm, were also confirmed by western blot and immunofluorescence assay. Our results therefore confirmed the arsenic-induced Nrf2 pathway activation in hepatocytes and also suggested that the translocation of Bach1 was associated with the regulation of Nrf2 pathway by arsenic. Hepatic Nrf2 pathway plays indispensable roles for cellular defenses against arsenic hepatotoxicity, and the interplay of Bach1 and Nrf2 may be helpful to understand the self-defensive responses and the diverse biological effects of arsenicals. PMID:23738048

  6. Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation.

    PubMed

    Nagata, Yosuke; Ohashi, Kazuya; Wada, Eiji; Yuasa, Yuki; Shiozuka, Masataka; Nonomura, Yoshiaki; Matsuda, Ryoichi

    2014-08-01

    Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermal growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor.

  7. Residual triose phosphate isomerase activity and color measurements to determine adequate cooking of ground beef patties.

    PubMed

    Sair, A I; Booren, A M; Berry, B W; Smith, D M

    1999-02-01

    The objectives were to (i) compare the use of triose phosphate isomerase (TPI) activity and internal color scores for determination of cooking adequacy of beef patties and (ii) determine the effect of frozen storage and fat content on residual TPI activity in ground beef. Ground beef patties (24.4% fat) were cooked to five temperatures ranging from 60.0 to 82.2 degrees C. TPI activity decreased as beef patty cooking temperature was increased from 60.0 to 71.1 degrees C; however, no difference (P > 0.05) in activity (6.3 U/kg meat) was observed in patties cooked to 71.1 degrees C and above. Degree of doneness color scores, a* values and b* values, of ground beef patties decreased as internal temperature was increased from 60.0 to 71.1 degrees C; however, temperature had no effect on L* values. TPI activity in raw ground beef after five freeze-thaw cycles did not differ from the control. Three freeze-thaw cycles of raw ground beef resulted in a 57.2% decrease in TPI activity after cooking. TPI activity of cooked beef increased during 2 months of frozen storage, but TPI activity in ground beef stored for 3 months or longer did not differ from the unfrozen control. While past research has shown color to be a poor indicator of adequate thermal processing, our results suggest that undercooked ground beef patties could be distinguished from those that had been adequately cooked following U.S. Department of Agriculture guidelines using residual TPI activity as a marker.

  8. Effects of low cell pH and elevated inorganic phosphate on the pCa-force relationship in single muscle fibers at near-physiological temperatures.

    PubMed

    Nelson, Cassandra R; Fitts, Robert H

    2014-04-01

    Intense muscle contraction induces high rates of ATP hydrolysis with resulting increases in Pi, H(+), and ADP, factors thought to induce fatigue by interfering with steps in the cross-bridge cycle. Force inhibition is less at physiological temperatures; thus the role of low pH in fatigue has been questioned. Effects of pH 6.2 and collective effects with 30 mM Pi on the pCa-force relationship were assessed in skinned fast and slow rat skeletal muscle fibers at 15 and 30°C. At 30°C, pH 6.2 + 30 mM Pi significantly depressed peak force in all fiber types, with the greatest effect in type IIx fibers. Across fiber types, Ca(2+) sensitivity was depressed by low pH and low pH + high Pi, with the greater effect at 30°C. For type IIx fibers at 30°C, half-maximal activation (pCa50) was 5.36 at pH 6.2 (no added Pi) and 4.98 at pH 6.2 + 30 mM Pi compared with 6.58 in the control condition (pH 7, no added Pi). At 30°C, n2, reflective of thick filament cooperativity, was unchanged by low cell pH but was depressed from 5.02 to 2.46 in type IIx fibers with pH 6.2 + 30 mM Pi. With acidosis, activation thresholds of all fiber types required higher free Ca(2+) at 15 and 30°C. With the exception of type IIx fibers, the Ca(2+) required to reach activation threshold increased further with added Pi. In conclusion, it is clear that fatigue-inducing effects of low cell pH and elevated Pi at near-physiological temperatures are substantial.

  9. Quantification of Galactose-1-Phosphate Uridyltransferase Enzyme Activity by Liquid Chromatography–Tandem Mass Spectrometry

    PubMed Central

    Li, Yijun; Ptolemy, Adam S.; Harmonay, Lauren; Kellogg, Mark; Berry, Gerard T.

    2013-01-01

    Background The diagnosis of galactosemia usually involves the measurement of galactose-1-phosphate uridyltransferase (GALT) activity. Traditional radioactive and fluorescent GALT assays are nonspecific, laborious, and/or lack sufficient analytical sensitivity. We developed a liquid chromatography–tandem mass spectrometry (LC-MS/MS)–based assay for GALT enzyme activity measurement. Method Our assay used stable isotope-labeled α-galactose-1-phosphate ([13C6]-Gal-1-P) as an enzyme substrate. Sample cleanup and separation were achieved by reversed-phase ion-pair chromatography, and the enzymatic product, isotope-labeled uridine diphosphate galactose ([13C6]-UDPGal), was detected by MS/MS at mass transition (571 > 323) and quantified by use of [13C6]-Glu-1-P (265 > 79) as an internal standard. Results The method yielded a mean (SD) GALT enzyme activity of 23.8 (3.8) µmol · (gHgb)−1 · h−1 in erythrocyte extracts from 71 controls. The limit of quantification was 0.04 µmol · (g Hgb)−1 · h−1 (0.2% of normal control value). Intraassay imprecision was determined at 4 different levels (100%, 25%, 5%, and 0.2% of the normal control values), and the CVs were calculated to be 2.1%, 2.5%, 4.6%, and 9.7%, respectively (n = 3). Interassay imprecision CVs were 4.5%, 6.7%, 8.2%, and 13.2% (n = 5), respectively. The assay recoveries at the 4 levels were higher than 90%. The apparent Km of the 2 substrates, Gal-1-P and UDPGlc, were determined to be 0.38 mmol/L and 0.071 mmol/L, respectively. The assay in erythrocytes of 33 patients with classical galactosemia revealed no detectable activity. Conclusions This LC-MS/MS–based assay for GALT enzyme activity will be useful for the diagnosis and study of biochemically heterogeneous patients with galactosemia, especially those with uncommon genotypes and detectable but low residual activities. PMID:20348403

  10. Quantification of galactose-1-phosphate uridyltransferase enzyme activity by liquid chromatography-tandem mass spectrometry.

    PubMed

    Li, Yijun; Ptolemy, Adam S; Harmonay, Lauren; Kellogg, Mark; Berry, Gerard T

    2010-05-01

    The diagnosis of galactosemia usually involves the measurement of galactose-1-phosphate uridyltransferase (GALT) activity. Traditional radioactive and fluorescent GALT assays are nonspecific, laborious, and/or lack sufficient analytical sensitivity. We developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based assay for GALT enzyme activity measurement. Our assay used stable isotope-labeled alpha- galactose-1-phosphate ([(13)C(6)]-Gal-1-P) as an enzyme substrate. Sample cleanup and separation were achieved by reversed-phase ion-pair chromatography, and the enzymatic product, isotope-labeled uridine diphosphate galactose ([(13)C(6)]-UDPGal), was detected by MS/MS at mass transition (571 > 323) and quantified by use of [(13)C(6)]-Glu-1-P (265 > 79) as an internal standard. The method yielded a mean (SD) GALT enzyme activity of 23.8 (3.8) mumol x (g Hgb)(-1) x h(-1) in erythrocyte extracts from 71 controls. The limit of quantification was 0.04 micromol x (g Hgb)(-1) x h(-1) (0.2% of normal control value). Intraassay imprecision was determined at 4 different levels (100%, 25%, 5%, and 0.2% of the normal control values), and the CVs were calculated to be 2.1%, 2.5%, 4.6%, and 9.7%, respectively (n = 3). Interassay imprecision CVs were 4.5%, 6.7%, 8.2%, and 13.2% (n = 5), respectively. The assay recoveries at the 4 levels were higher than 90%. The apparent K(m) of the 2 substrates, Gal-1-P and UDPGlc, were determined to be 0.38 mmol/L and 0.071 mmol/L, respectively. The assay in erythrocytes of 33 patients with classical galactosemia revealed no detectable activity. This LC-MS/MS-based assay for GALT enzyme activity will be useful for the diagnosis and study of biochemically heterogeneous patients with galactosemia, especially those with uncommon genotypes and detectable but low residual activities.

  11. Modulation of arginine decarboxylase activity from Mycobacterium smegmatis. Evidence for pyridoxal-5'-phosphate-mediated conformational changes in the enzyme.

    PubMed

    Balasundaram, D; Tyagi, A K

    1989-08-01

    Arginine decarboxylase (arginine carboxy-lyase, EC 4.1.1.19) from Mycobacterium smegmatis, TMC 1546 has been purified to homogeneity. The enzyme has a molecular mass of 232 kDa and a subunit mass of 58.9 kDa. The enzyme from mycobacteria is totally dependent on pyridoxal 5'-phosphate for its activity at its optimal pH and, unlike that from Escherichia coli, Mg2+ does not play an active role in the enzyme conformation. The enzyme is specific for arginine (Km = 1.6 mM). The holoenzyme is completely resolved in dialysis against hydroxylamine. Reconstitution of the apoenzyme with pyridoxal 5'-phosphate shows sigmoidal binding characteristics at pH 8.4 with a Hill coefficient of 2.77, whereas at pH 6.2 the binding is hyperbolic in nature. The kinetics of reconstitution at pH 8.4 are apparently sigmoidal, indicating the occurrence of two binding types of differing strengths. A low-affinity (Kd = 22.5 microM) binding to apoenzyme at high pyridoxal 5'-phosphate concentrations and a high-affinity (Kd = 3.0 microM) binding to apoenzyme at high pyridoxal 5'-phosphate concentrations. The restoration of full activity occurred in parallel with the tight binding (high affinity) of pyridoxal 5'-phosphate to the apoenzyme. Along with these characteristics, spectral analyses of holoenzyme and apoenzyme at pH 8.4 and pH 6.2 indicate a pH-dependent modulation of coenzyme function. Based on the pH-dependent changes in the polarity of the active-site environment, pyridoxal 5'-phosphate forms different Schiff-base tautomers at pH 8.4 and pH 6.2 with absorption maxima at 415 nm and 333 nm, respectively. These separate forms of Schiff-base confer different catalytic efficiencies to the enzyme.

  12. Short-term hypothermia activates hepatic mitochondrial sn-glycerol-3-phosphate dehydrogenase and thermogenic systems.

    PubMed

    Bobyleva, V; Pazienza, L; Muscatello, U; Kneer, N; Lardy, H

    2000-08-15

    The contribution of the sn-glycerol-3-phosphate (G-3-P) shuttle in the control of energy metabolism is well established. It is also known that its activity may be modulated by hormones involved in thermogenesis, such as thyroid hormones or dehydroepiandrosterone and its metabolites, that act by inducing de novo synthesis of mitochondrial G-3-P dehydrogenase (mGPDH). However, little is known as to the factors that may influence the activity without enzyme induction. In the present study we investigated the possible role of the G-3-P shuttle in the thermogenic response to different hypothermic stresses. It was found that a decrease of body temperature causes the liver rapidly to enhance mGPDH activity and G-3-P-dependent respiration. The enhancement, which does not result from de novo synthesis of enzymes, has the potential of increasing heat production both by decreased ATP synthesis during the oxidation of G-3-P and by activation of the glycolytic pathway.

  13. Dengue Virus NS1 Protein Modulates Cellular Energy Metabolism by Increasing Glyceraldehyde-3-Phosphate Dehydrogenase Activity

    PubMed Central

    Allonso, Diego; Andrade, Iamara S.; Conde, Jonas N.; Coelho, Diego R.; Rocha, Daniele C. P.; da Silva, Manuela L.; Ventura, Gustavo T.

    2015-01-01

    ABSTRACT Dengue is one of the main public health concerns worldwide. Recent estimates indicate that over 390 million people are infected annually with the dengue virus (DENV), resulting in thousands of deaths. Among the DENV nonstructural proteins, the NS1 protein is the only one whose function during replication is still unknown. NS1 is a 46- to 55-kDa glycoprotein commonly found as both a membrane-associated homodimer and a soluble hexameric barrel-shaped lipoprotein. Despite its role in the pathogenic process, NS1 is essential for proper RNA accumulation and virus production. In the present study, we identified that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) interacts with intracellular NS1. Molecular docking revealed that this interaction occurs through the hydrophobic protrusion of NS1 and the hydrophobic residues located at the opposite side of the catalytic site. Moreover, addition of purified recombinant NS1 enhanced the glycolytic activity of GAPDH in vitro. Interestingly, we observed that DENV infection promoted the relocalization of GAPDH to the perinuclear region, where NS1 is commonly found. Both DENV infection and expression of NS1 itself resulted in increased GAPDH activity. Our findings indicate that the NS1 protein acts to increase glycolytic flux and, consequently, energy production, which is consistent with the recent finding that DENV induces and requires glycolysis for proper replication. This is the first report to propose that NS1 is an important modulator of cellular energy metabolism. The data presented here provide new insights that may be useful for further drug design and the development of alternative antiviral therapies against DENV. IMPORTANCE Dengue represents a serious public health problem worldwide and is caused by infection with dengue virus (DENV). Estimates indicate that half of the global population is at risk of infection, with almost 400 million cases occurring per year. The NS1 glycoprotein is found in both the

  14. Dengue Virus NS1 Protein Modulates Cellular Energy Metabolism by Increasing Glyceraldehyde-3-Phosphate Dehydrogenase Activity.

    PubMed

    Allonso, Diego; Andrade, Iamara S; Conde, Jonas N; Coelho, Diego R; Rocha, Daniele C P; da Silva, Manuela L; Ventura, Gustavo T; Silva, Emiliana M; Mohana-Borges, Ronaldo

    2015-12-01

    Dengue is one of the main public health concerns worldwide. Recent estimates indicate that over 390 million people are infected annually with the dengue virus (DENV), resulting in thousands of deaths. Among the DENV nonstructural proteins, the NS1 protein is the only one whose function during replication is still unknown. NS1 is a 46- to 55-kDa glycoprotein commonly found as both a membrane-associated homodimer and a soluble hexameric barrel-shaped lipoprotein. Despite its role in the pathogenic process, NS1 is essential for proper RNA accumulation and virus production. In the present study, we identified that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) interacts with intracellular NS1. Molecular docking revealed that this interaction occurs through the hydrophobic protrusion of NS1 and the hydrophobic residues located at the opposite side of the catalytic site. Moreover, addition of purified recombinant NS1 enhanced the glycolytic activity of GAPDH in vitro. Interestingly, we observed that DENV infection promoted the relocalization of GAPDH to the perinuclear region, where NS1 is commonly found. Both DENV infection and expression of NS1 itself resulted in increased GAPDH activity. Our findings indicate that the NS1 protein acts to increase glycolytic flux and, consequently, energy production, which is consistent with the recent finding that DENV induces and requires glycolysis for proper replication. This is the first report to propose that NS1 is an important modulator of cellular energy metabolism. The data presented here provide new insights that may be useful for further drug design and the development of alternative antiviral therapies against DENV. Dengue represents a serious public health problem worldwide and is caused by infection with dengue virus (DENV). Estimates indicate that half of the global population is at risk of infection, with almost 400 million cases occurring per year. The NS1 glycoprotein is found in both the intracellular and the

  15. Pharmacological evaluation of poly(3-methylthiophene) and its titanium(IV)phosphate nanocomposite: DNA interaction, molecular docking, and cytotoxic activity.

    PubMed

    Baig, Umair; Gondal, M A; Alam, Md Fazle; Wani, Waseem A; Younus, Hina

    2016-11-01

    Cancer and pathogenic microbial diseases have terribly affected human health over a longer period of time. In response to the increasing casualties due to cancer and microbial diseases, unique poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate composite were prepared via in-situ oxidative chemical polymerization in this work. The poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate composite were well characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. DNA binding studies by UV-Visible and fluorescence spectroscopic investigations indicated strong binding affinities of poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite; leading to structural damage of DNA. Poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite showed stronger interactions with DNA as compared to poly(3-methylthiophene) and from dye displacement assay it was confirmed that mode of binding of both the formulations was intercalative. The antimicrobial screening revealed that polymer and its composite displayed stronger antibacterial effects than ampicillin against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhimurium. Besides, the poly(3-methylthiophene) and poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite showed dose dependent effects towards estrogen receptor positive breast cancer (MCF-7) and estrogen receptor negative breast cancer (MDA-MB-231) cell lines; with poly(3-methylthiophene)-titanium(IV)phosphate nanocomposite showing better activities against both cell lines. In all in-vitro biological investigations, poly(3-methylthiophene)-titanium(IV)phosphate composite showed superior properties to that of the pure poly(3-methylthiophene), which encouraged us to suggest its potential as future therapeutic gear in drug delivery and other allied fields.

  16. Detection of phosphohydrolytic enzyme activity through the oxygen isotope composition of dissolved phosphate

    NASA Astrophysics Data System (ADS)

    Colman, A. S.

    2016-02-01

    Phosphohydrolytic enzymes play an important role in phosphorus remineralization. As they release phosphate (Pi) from various organophosphorus compounds, these enzymes facilitate the transfer of oxygen atoms from water to the phosphoryl moieties. Most such enzymatic reactions impart a significant isotopic fractionation to the oxygen transferred. If this reaction occurs within a cell, then the resultant oxygen isotope signal is overprinted by continued recycling of the Pi. However, if this reaction occurs extracellularly, then the isotopic signal will be preserved until the Pi is transported back into a cell. Thus, the oxygen isotope composition of Pi (δ18Op) in an aquatic ecosystem can serve as a useful indicator of the mechanisms by which P is remineralized. We develop a time-dependent model illustrating the sensitivity of the δ18O of dissolved phosphate to various modes of P remineralization. The model is informed by cell lysis experiments that reveal the relative proportions of P­i that are directly liberated from cytosol vs. regenerated from co-liberated dissolved organic phosphorus compounds via extracellular hydrolysis. By incorporating both cellular uptake and release fluxes of P, we show that the degree of isotopic disequilibrium in an aquatic ecosystem can be a strong indicator of P remineralization mode. Apparent oxygen isotope equilibrium between Pi and water arises in this model as a steady-state scenario in which fractionation upon cellular uptake of Pi counterbalances the hydrolytic source flux of disequilibrated Pi. Low and high rates of extracellular phosphohydrolase activity are shown to produce steady-state δ18Op values that are respectively above or below thermodynamic equilibrium compositions.

  17. Derivatives of phosphate Schiff base transition metal complexes: synthesis, studies and biological activity

    NASA Astrophysics Data System (ADS)

    El-Wahab, Z. H. Abd; El-Sarrag, M. R.

    2004-01-01

    We report the synthesis and structural characterization of series of tetra- and hexacoordinate metal chelate complexes of phosphate Schiff base ligands having the general composition LMX n·H 2O and L 2MX n (L=phosphate Schiff base ligand; M=Ag +, Mn 2+, Cu 2+, Zn 2+, Cd 2+, Hg 2+, or Fe 3+ and X=NO 3-, Br - or Cl -). The structure of the prepared compounds was investigated using elemental analysis, IR, 1H and 31P NMR, UV-vis, mass spectra, solid reflectance, magnetic susceptibility and conductance measurements as well as conductometric titration. In all the complexes studied, the ligands act as a chelate ligand with coordination involving the phosphateO-atom and the azomethineN-atom. IR, solid reflectance spectra and magnetic moment measurement are used to infer the structure and to illustrate the coordination capacity of ligand. IR spectra show the presence of coordinated nitrate and water molecule, the magnetic moments of all complexes show normal magnetic behavior and the electronic spectra of the metal complexes indicate a tetra- and octahedral structure for Mn 2+, octahedral structure of Fe 3+ and both square-planar and distorted octahedral structure for Cu 2+ complexes. Antimicrobial activity of the ligands and their complexes were tested using the disc diffusion method and the chosen strains include Staphylococcus aureus, Pseudomonas aereuguinosa, Klebsiella penumoniae, Escherichia coli, Microsporum canis, Trichophyton mentagrophyte and Trichophyton rubrum. Some known antibiotics are included for the sake of comparison and the chosen antibiotic are Amikacin, Doxycllin, Augmantin, Sulperazon, Unasyn, Septrin, Cefobid, Ampicillin, Nitrofurantion, Traivid and Erythromycin.

  18. Phosphate Uptake by Phosphate-Starved Euglena

    PubMed Central

    BLUM, J. J.

    1966-01-01

    Phosphate-deprived Euglena acquire the ability to rapidly in-corporate added phosphate and, also, synthesize an induced acid phosphatase localized in the pellicle. The phosphate uptake system is saturated at low concentrations of phosphate and is inhibited by dinitrophenol, by low temperature, by K+, Li+, and Na+ ions, and competitively by arsenate. The orthophosphate incorporated into the cell is rapidly converted into organic forms but enough remains unesterified to suggest that the uptake is an active transport process. The data do not rule out the possibility that the induced phosphatase is involved in the transport process. PMID:5924104

  19. A serum factor that activates the phosphatidylinositol phosphate signaling system in Xenopus oocytes.

    PubMed Central

    Tigyi, G; Dyer, D; Matute, C; Miledi, R

    1990-01-01

    Blood sera from many vertebrate species elicit large oscillatory chloride currents in oocytes from the frog Xenopus laevis. Rabbit serum was active at dilutions as great as one part in 10 million. Intracellularly applied serum was ineffective, and externally applied serum failed to trigger oscillatory currents when the intracellular level of ionized calcium was prevented from rising by loading the oocyte with EGTA. The serum also caused an increase of inositol 1,4,5-trisphosphate in the oocyte. We conclude that serum contains a factor which activates a membrane receptor that is coupled to the phosphatidylinositol second messenger system. The active factor is a protein with an apparent molecular mass of 60-70 kDa in gel permeation chromatography. Although the normal function of the serum factor is still unknown, it may have far-reaching implications, because it acts on the multifunctional phosphatidylinositol phosphate signaling system. Also, because of its great potency the serum factor and Xenopus oocytes are very useful for probing the operation of the phosphatidylinositol system. PMID:1689488

  20. Aldosterone impairs vascular reactivity by decreasing glucose-6-phosphate dehydrogenase activity

    PubMed Central

    Leopold, Jane A.; Dam, Aamir; Maron, Bradley A.; Scribner, Anne W.; Liao, Ronglih; Handy, Diane E.; Stanton, Robert C.; Pitt, Bertram; Loscalzo, Joseph

    2013-01-01

    Hyperaldosteronism is associated with impaired vascular reactivity; however, the mechanism by which aldosterone promotes endothelial dysfunction remains unknown. Glucose-6-phosphate dehydrogenase (G6pd), the principal source of Nadph, modulates vascular function by limiting oxidant stress to preserve bioavailable nitric oxide (NO•). In these studies, we show that aldosterone (10−9-10−7 mol/l) decreases endothelial G6pd expression and activity in vitro resulting in increased oxidant stress and decreased cGMP levels similar to what is observed in G6pd-deficient cells. Aldosterone decreases G6pd expression by protein kinase A activation to increase expression of Crem, which interferes with Creb binding to the G6pd promoter. In vivo, infusion of aldosterone decreases vascular G6pd expression and impairs vascular reactivity. These effects are abrogated by spironolactone or vascular gene transfer of G6pd. These studies demonstrate that aldosterone induces a G6pd-deficient phenotype to impair endothelial function; aldosterone antagonism or gene transfer of G6pd improves vascular reactivity by restoring G6pd activity. PMID:17273168

  1. Antibacterial activity evaluation of bioactive glass and biphasic calcium phosphate nanopowders mixtures

    NASA Astrophysics Data System (ADS)

    Nazemi, Zahra; Mehdikhani-Nahrkhalaji, Mehdi; Haghbin-Nazarpak, Masoumeh; Staji, Hamid; Kalani, Mohammad Mehdi

    2016-12-01

    The aim of this work was to evaluate the antibacterial activity of bioactive glass (BG) and biphasic calcium phosphate (BCP) nanopowders mixtures for the first time. 37S BG and BCP (50% HA-50% β-TCP) nanopowders were prepared via sol-gel technique. Characterization techniques such as X-ray diffraction, scanning electron microscopy, transition electron microscopy, and X-ray fluorescent. The antibacterial activity was studied using Escherichia coli and Salmonella typhi as gram-negative, and Staphylococcus aureus as gram-positive bacteria. The antibacterial effect of BG, BCP nanopowders, and their mixtures was evaluated at different concentrations. The 37S BG nanopowders showed minimum bactericidal concentration at 25 mg/ml. At broth concentrations below 300 mg/ml, BCP showed no antibacterial activity. BCP and BG nanopowders mixture (M2) with 60/40 ratio of BCP/BG showed noticeable antibacterial effect. It was concluded that BCP and 37S BG nanopowders mixture could be used as a good candidate for dental and orthopedic applications.

  2. Interactions between organic additives and active powders in water-based lithium iron phosphate electrode slurries

    NASA Astrophysics Data System (ADS)

    Li, Chia-Chen; Lin, Yu-Sheng

    2012-12-01

    The interactions of organic additives with active powders are investigated and are found to have great influence on the determination of the mixing process for preparing electrode slurries with good dispersion and electrochemical properties of lithium iron phosphate (LiFePO4) electrodes. Based on the analyses of zeta potential, sedimentation, and rheology, it is shown that LiFePO4 prefers to interact with styrene-butadiene rubber (SBR) relative to other organic additives such as sodium carboxymethyl cellulose (SCMC), and thus shows preferential adsorption by SBR, whereas SBR has much lower efficiency than SCMC in dispersing LiFePO4. Therefore, for SCMC to interact with and disperse LiFePO4 before the interaction of LiFePO4 with SBR, it is suggested to mix SCMC with LiFePO4 prior to the addition of SBR during the slurry preparation process. For the electrode prepared via the suggested process, i.e., the sequenced adding process in which SCMC is mixed with active powders prior to the addition of SBR, a much better electrochemical performance is obtained than that of the one prepared via the process referred as the simultaneous adding process, in which mixing of SCMC and SBR with active powders in simultaneous.

  3. Structural and Chemical Basis for Glucosamine 6-Phosphate Binding and Activation of the glmS Ribozyme

    SciTech Connect

    Cochrane, J.; Lipchock, S; Smith, K; Strobel, S

    2009-01-01

    The glmS ribozyme is the first naturally occurring catalytic RNA that relies on an exogenous, nonnucleotide cofactor for reactivity. From a biochemical perspective, the glmS ribozyme derived from Bacillus anthracis is the best characterized. However, much of the structural work to date has been done on a variant glmS ribozyme, derived from Thermoanaerobacter tengcongensis. Here we present structures of the B. anthracis glmS ribozyme in states before the activating sugar, glucosamine 6-phosphate (GlcN6P), has bound and after the reaction has occurred. These structures show an active site preorganized to bind GlcN6P that retains some affinity for the sugar even after cleavage of the RNA backbone. A structure of an inactive glmS ribozyme with a mutation distal from the ligand-binding pocket highlights a nucleotide critical to the reaction that does not affect GlcN6P binding. Structures of the glmS ribozyme bound to a naturally occurring inhibitor, glucose 6-phosphate (Glc6P), and a nonnatural activating sugar, mannosamine 6-phosphate (MaN6P), reveal a binding mode similar to that of GlcN6P. Kinetic analyses show a pH dependence of ligand binding that is consistent with titration of the cofactor's phosphate group and support a model in which the major determinant of activity is the sugar amine independent of its stereochemical presentation.

  4. Optimizations of particle size and pulp density for solubilization of rock phosphate by a microbial consortium from activated sludge.

    PubMed

    Xiao, Chunqiao; Wu, Xiaoyan; Liu, Tingting; Xu, Guang; Chi, Ruan

    2016-12-29

    Microbial solubilization of rock phosphate is getting more and more attention recently. However, the microorganisms used in previous studies were mostly single or known species, and seldom studies focused on the mixed microorganisms or microbial consortia from natural environments. In this study, a microbial consortium taken from activated sludge was used to solubilize two different mid-low-grade rock phosphates. The results showed that the microbial consortium could effectively solubilize the rock phosphates in National Botanical Research Institute's phosphate growth medium and released soluble phosphorus in the broth. The biomass increased gradually, whereas the pH decreased sharply during the solubilizing process. The maximum phosphorus solubilization was recorded at particle size of 150 µm. Higher or lower than this optimal particle size, the phosphorus solubilization decreased. The phosphorus solubilization gradually decreased with a larger pulp density from 1 to 5%, and the optimal pulp density was 1%. The solubilization level of microbial consortium varied with different rock phosphates. The results revealed that the soluble phosphorus released from high-silicon ore was higher than which from high-magnesium ore. A strong positive correlation between biomass and phosphorus solubilization in the broth was observed from regression analysis results, and the phosphorus solubilization also had a significant negative correlation with pH in the broth.

  5. Sphingosine-1-phosphate mediates epidermal growth factor-induced muscle satellite cell activation

    SciTech Connect

    Nagata, Yosuke Ohashi, Kazuya; Wada, Eiji; Yuasa, Yuki; Shiozuka, Masataka; Nonomura, Yoshiaki; Matsuda, Ryoichi

    2014-08-01

    Skeletal muscle can regenerate repeatedly due to the presence of resident stem cells, called satellite cells. Because satellite cells are usually quiescent, they must be activated before participating in muscle regeneration in response to stimuli such as injury, overloading, and stretch. Although satellite cell activation is a crucial step in muscle regeneration, little is known of the molecular mechanisms controlling this process. Recent work showed that the bioactive lipid sphingosine-1-phosphate (S1P) plays crucial roles in the activation, proliferation, and differentiation of muscle satellite cells. We investigated the role of growth factors in S1P-mediated satellite cell activation. We found that epidermal growth factor (EGF) in combination with insulin induced proliferation of quiescent undifferentiated mouse myoblast C2C12 cells, which are also known as reserve cells, in serum-free conditions. Sphingosine kinase activity increased when reserve cells were stimulated with EGF. Treatment of reserve cells with the D-erythro-N,N-dimethylsphingosine, Sphingosine Kinase Inhibitor, or siRNA duplexes specific for sphingosine kinase 1, suppressed EGF-induced C2C12 activation. We also present the evidence showing the S1P receptor S1P2 is involved in EGF-induced reserve cell activation. Moreover, we demonstrated a combination of insulin and EGF promoted activation of satellite cells on single myofibers in a manner dependent on SPHK and S1P2. Taken together, our observations show that EGF-induced satellite cell activation is mediated by S1P and its receptor. - Highlights: • EGF in combination with insulin induces proliferation of quiescent C2C12 cells. • Sphingosine kinase activity increases when reserve cells are stimulated with EGF. • EGF-induced activation of reserve cells is dependent on sphingosine kinase and ERK. • The S1P receptor S1P2 is involved in EGF-induced reserve cell activation. • EGF-induced reserve cell activation is mediated by S1P and its

  6. The desorption and reactivity of butanol adsorbed on lithium iron phosphate (LISICON) activated in a hydrogen plasma

    NASA Astrophysics Data System (ADS)

    Pylinina, A. I.; Mikhalenko, I. I.; Yagodovskaya, T. V.; Yagodovskii, V. D.

    2010-12-01

    The reactivity and desorption of butanol-2 adsorbed on Li3Fe2(PO4)3 not subjected and subjected to treatment in a glow discharge hydrogen plasma were studied under flow conditions with a gas chromatographic analysis of products. X-ray photoelectron spectroscopy data showed that the number of phosphate groups on the surface of the phosphate was two times larger than the stoichiometric number and increased after plasma chemical treatment. The strength of butanol-phosphate bonds also increased, and the selectivity of alcohol decomposition with the formation of an olefin (dehydration) and ketone (dehydrogenation) changed. After plasma treatment, dehydrogenation centers were deactivated. The selectivities of alcohol transformations in the adsorbed state and under vapor phase conditions were different. Ketone was formed from adsorbed alcohol because the activation energies of dehydrogenation were equal for the two reaction variants.

  7. Equilibrium and kinetic studies of adsorption of phosphate onto ZnCl2 activated coir pith carbon.

    PubMed

    Namasivayam, C; Sangeetha, D

    2004-12-15

    Phosphate removal from aqueous solution was investigated using ZnCl(2)-activated carbon developed from coir pith, an agricultural solid waste. Studies were conducted to delineate the effect of contact time, adsorbent dose, phosphate concentration, pH, and temperature. The adsorption equilibrium data followed both Langmuir and Freundlich isotherms. Langmuir adsorption capacity was found to be 5.1 mg/g. Adsorption followed second-order kinetics. The removal was maximum in the pH range 3-10. pH effect and desorption studies showed that adsorption occurred by both ion exchange and chemisorption mechanisms. Adsorption was found to be spontaneous and endothermic. Effect of foreign ions on adsorption shows that perchlorate, sulfate, and selenite decreased the percent removal of phosphate.

  8. Activated platelets release sphingosine 1-phosphate and induce hypersensitivity to noxious heat stimuli in vivo

    PubMed Central

    Weth, Daniela; Benetti, Camilla; Rauch, Caroline; Gstraunthaler, Gerhard; Schmidt, Helmut; Geisslinger, Gerd; Sabbadini, Roger; Proia, Richard L.; Kress, Michaela

    2015-01-01

    At the site of injury activated platelets release various mediators, one of which is sphingosine 1-phosphate (S1P). It was the aim of this study to explore whether activated human platelets had a pronociceptive effect in an in vivo mouse model and whether this effect was based on the release of S1P and subsequent activation of neuronal S1P receptors 1 or 3. Human platelets were prepared in different concentrations (105/μl, 106/μl, 107/μl) and assessed in mice with different genetic backgrounds (WT, S1P1fl/fl, SNS-S1P1−/−, S1P3−/−). Intracutaneous injections of activated human platelets induced a significant, dose-dependent hypersensitivity to noxious thermal stimulation. The degree of heat hypersensitivity correlated with the platelet concentration as well as the platelet S1P content and the amount of S1P released upon platelet activation as measured with LC MS/MS. Despite the significant correlations between S1P and platelet count, no difference in paw withdrawal latency (PWL) was observed in mice with a global null mutation of the S1P3 receptor or a conditional deletion of the S1P1 receptor in nociceptive primary afferents. Furthermore, neutralization of S1P with a selective anti-S1P antibody did not abolish platelet induced heat hypersensitivity. Our results suggest that activated platelets release S1P and induce heat hypersensitivity in vivo. However, the platelet induced heat hypersensitivity was caused by mediators other than S1P. PMID:25954148

  9. Anti-tumor and immunomodulatory activity of iron hepta-tungsten phosphate oxygen clusters complex.

    PubMed

    Zhang, Bisong; Qiu, Jianping; Wu, Changsheng; Li, Yunxia; Liu, Zhenxiang

    2015-12-01

    Polyoxometalates (POMs) have attracted a considerable attention due to their unique structural characteristics, physicochemical properties and biological activities. In this study, iron hepta-tungsten phosphate oxygen clusters complex Na12H[Fe(HPW7O28)2]·44H2O (IHTPO) was synthesized and evaluated for in vitro cytotoxic activities on human hepatoma HepG2, leukemia K562, lung carcinoma A549, and large cell lung cancer NCI-H460 cells, therapeutic efficacies on mice transplantable tumor, and immunomodulatory potentials on the immune response in tumor-bearing mice. IHTPO exhibited lower in vitro cytotoxic activities against four human tumor cell lines, with the IC50 values being higher than 62.5μM (ca. 300μg/ml). IHTPO, however, significantly inhibited the growth of S180 sarcoma transplanted in mice. It was further showed that IHTPO could not only significantly promote splenocytes proliferation, NK cell and CTL activity from splenocytes, but remarkably enhance serum antigen-specific IgG, IgG2a and IgG2b antibody levels in S180-bearing mice. IHTPO also significantly promoted Th1 cytokines IFN-γ and IL-2 production, and up-regulated the mRNA expression levels of IFN-γ, IL-2 and Th1 transcription factors T-bet and STAT-4 in splenocytes from the S180-bearing mice. These results suggested that IHTPO significantly inhibited the growth of mice transplantable tumor, and that its in vivo antitumor activity might be achieved by improving Th1 protective cell-mediated immunity. IHTPO could act as antitumor agent with immunomodulatory activity.

  10. Inorganic concepts relevant to metal binding, activity, and toxicity in a biological system

    SciTech Connect

    Hoeschele, J.D. . Parke-Davis Pharmaceutical Research Div.); Turner, J.E.; England, M.W. )

    1990-01-01

    The purpose of this paper is to review selected physical and inorganic concepts and factors which might be important in assessing and/or understanding the fact and disposition of a metal system in a biological environment. Hopefully, such inquiries will ultimately permit us to understand, rationalize, and predict differences and trends in biological effects as a function of the basic nature of a metal system and, in optimal cases, serve as input to a system of guidelines for the notion of Chemical Dosimetry.'' The plan of this paper is to first review, in general terms, the basic principles of the Crystal Field Theory (CFT), a unifying theory of bonding in metal complexes. This will provide the necessary theoretical background for the subsequent discussion of selected concepts and factors. 21 refs., 7 figs., 6 tabs.

  11. Effect of an organophosphate pesticide, monocrotophos, on phosphate-solubilizing efficiency of soil fungal isolates.

    PubMed

    Jain, Rachna; Garg, Veena; Saxena, Jyoti

    2015-01-01

    Soil is a sink of pesticide residues as well as microorganisms. Fungi are well known for solubilization of inorganic phosphates, and this activity of fungal isolates may be affected by the presence of pesticide residues in the soil. In the present study, five generically different fungal isolates, viz. Aspergillus niger JQ660373, Aspergillus flavus, Penicillium aculeatum JQ660374, Fusarium pallidoroseum and Macrophomina sp., were tested and compared for their phosphate-solubilizing ability in the absence and presence of monocrotophos (500 mg L(-1)). After 168 h of incubation, four times high amount of tricalcium phosphate was solubilized by isolates in the growth medium containing monocrotophos in comparison to control (without monocrotophos). Concurrently, 78 % of the applied monocrotophos was degraded by these fungal isolates. Kinetics of phosphate solubilization shifted from logarithmic to power model in the presence of monocrotophos. Similarly, the phosphatase activity was also found significantly high in the presence of monocrotophos. The combined order of phosphate solubilization as well as monocrotophos degradation was found to be A. niger JQ660373 > P. aculeatum JQ660374 > A. flavus > F. pallidoroseum > Macrophomina sp. On the contrary, phosphate solubilization negatively correlated with the pH of the growth medium. Hence, it could be concluded that these fungal species efficiently solubilize inorganic phosphates and monocrotophos poses a positive effect on their ability and in turn degraded by them. To the best of our knowledge, this is the first report on P solubilization by Macrophomina sp. and F. pallidoroseum.

  12. Inorganic Carbon Turnover caused by Digestion of Carbonate Sands and Metabolic Activity of Holothurians

    SciTech Connect

    Schneider, Kenneth; Silverman, Jacob; Kravitz, Benjamin S.; Rivlin, Tanya; Schneider-Mor, Aya; Barbosa, Sergio; Byrne, Maria; Caldeira, Ken

    2013-11-20

    Recent measurements have shown that holothurians (sea cucumbers) play an important role in the cycling of CaCO3 in tropical coral reef systems through ingestion and processing of carbonate sediment. In this study inorganic additional aspects of carbon turnover were determined in laboratory incubations of Holothuria atra, H. leucospilota and Stichopus herrmanni from One Tree Reef, Great Barrier Reef. The pH values of the gut lumen ranged from 6.1 to 6.7 in animals with empty digestive tracts as opposed to 7.0 to 7.6 when digestive tracts were filled with sediment. Empty gut volume estimates for H. atra and S. herrmanni were 36 ± 4 mL and 151 ± 14 mL, respectively. Based on these measurements it is estimated that these species process 19 ± 2kg and 80 ± 7kg CaCO3 sand yr-1 per individual, respectively. The annual dissolution rates of H. atra and S. herrmanni of 6.5±1.9g and 9.6±1.4g, respectively, suggest that 0.05±0.02% and 0.1±0.02% of the CaCO3 processed through their gut annually is dissolved. During the incubations the CaCO3 dissolution was 0.07±0.01%, 0.04±0.01% and 0.21±0.05% of the fecal casts for H. atra, H. leucospilota and S. herrmanni, respectively. The CaCO3 saturation state for both aragonite and calcite minerals during laboratory incubations decreased markedly due to a greater increase in dissolved inorganic carbon (DIC) relative to total alkalinity (AT) as a result of respiration by the animals. Our results support the hypothesis that deposit feeders such as sea cucumbers play an important ecological role in the coral reef CaCO3 cycle.

  13. Inorganic carbon turnover caused by digestion of carbonate sands and metabolic activity of holothurians

    NASA Astrophysics Data System (ADS)

    Schneider, Kenneth; Silverman, Jacob; Kravitz, Ben; Rivlin, Tanya; Schneider-Mor, Aya; Barbosa, Sergio; Byrne, Maria; Caldeira, Ken

    2013-11-01

    Recent measurements have shown that holothurians (sea cucumbers) may play an important role in the cycling of CaCO3 in tropical coral reef systems through ingestion and processing of carbonate sediment. In this report, we present estimates of inorganic carbon turnover rates determined from laboratory incubations of Holothuria atra, Holothuria leucospilota and Stichopus herrmanni. The pH values of the gut lumen ranged from 7.0 to 7.6 when digestive tracts were filled with sediment compared with 6.1-6.7 in animals with empty digestive tracts. Empty gut volume estimates for H. atra and S. herrmanni were 36 ± 4 mL and 151 ± 14 mL, respectively. Based on these measurements and the density and porosity of carbonate sediments of coral reefs, it is estimated that these species process 19 ± 2 kg and 80 ± 7 kg CaCO3 sand yr-1 per individual, respectively. The annual CaCO3 dissolution rates per H. atra and S. herrmanni individual are estimated to be 6.5 ± 1.9 g and 9.6 ± 1.4 g, respectively, suggesting that 0.05 ± 0.02% and 0.1 ± 0.02% of the CaCO3 processed through their gut annually is dissolved. During incubations the CaCO3 dissolution of the fecal casts was 0.07 ± 0.01%, 0.04 ± 0.01% and 0.21 ± 0.05% for H. atra, H. leucospilota and S. herrmanni, respectively. The CaCO3 saturation state in the incubation seawater decreased markedly due to a greater increase in dissolved inorganic carbon (DIC) relative to total alkalinity (AT) as a result of respiration by the animals. Our results support the hypothesis that deposit feeders such as sea cucumbers play an important ecological role in the coral reef CaCO3 cycle.

  14. Reducing the Genetic Redundancy of Arabidopsis PHOSPHATE TRANSPORTER1 Transporters to Study Phosphate Uptake and Signaling1[OPEN

    PubMed Central

    Ayadi, Amal; David, Pascale; Arrighi, Jean-François; Chiarenza, Serge; Thibaud, Marie-Christine; Nussaume, Laurent; Marin, Elena

    2015-01-01

    Arabidopsis (Arabidopsis thaliana) absorbs inorganic phosphate (Pi) from the soil through an active transport process mediated by the nine members of the PHOSPHATE TRANSPORTER1 (PHT1) family. These proteins share a high level of similarity (greater than 61%), with overlapping expression patterns. The resulting genetic and functional redundancy prevents the analysis of their specific roles. To overcome this difficulty, our approach combined several mutations with gene silencing to inactivate multiple members of the PHT1 family, including a cluster of genes localized on chromosome 5 (PHT1;1, PHT1;2, and PHT1;3). Physiological analyses of these lines established that these three genes, along with PHT1;4, are the main contributors to Pi uptake. Furthermore, PHT1;1 plays an important role in translocation from roots to leaves in high phosphate conditions. These genetic tools also revealed that some PHT1 transporters likely exhibit a dual affinity for phosphate, suggesting that their activity is posttranslationally controlled. These lines display significant phosphate deficiency-related phenotypes (e.g. biomass and yield) due to a massive (80%–96%) reduction in phosphate uptake activities. These defects limited the amount of internal Pi pool, inducing compensatory mechanisms triggered by the systemic Pi starvation response. Such reactions have been uncoupled from PHT1 activity, suggesting that systemic Pi sensing is most probably acting downstream of PHT1. PMID:25670816

  15. Cellular recovery of glyceraldehyde-3-phosphate dehydrogenase activity and thiol status after exposure to hydroperoxides

    SciTech Connect

    Brodie, A.E.; Reed, D.J. )

    1990-01-01

    The activity of the thiol-dependent enzyme glyceraldehyde-3-phosphate dehydrogenase (GPD), in vertebrate cells, was modulated by a change in the intracellular thiol:disulfide redox status. Human lung carcinoma cells (A549) were incubated with 1-120 mM H2O2, 1-120 mM t-butyl hydroperoxide, 1-6 mM ethacrynic acid, or 0.1-10 mM N-ethylmaleimide for 5 min. Loss of reduced protein thiols, as measured by binding of the thiol reagent iodoacetic acid to GPD, and loss of GPD enzymatic activity occurred in a dose-dependent manner. Incubation of the cells, following oxidative treatment, in saline for 30 min or with 20 mM dithiothreitol (DTT) partially reversed both changes in GPD. The enzymatic recovery of GPD activity was observed either without addition of thiols to the medium or by incubation of a sonicated cell mixture with 2 mM cysteine, cystine, cysteamine, or glutathione (GSH); GSSG had no effect. Treatment of cells with buthionine sulfoximine (BSO) to decrease cellular GSH by varying amounts caused a dose-related increase in sensitivity of GPD activity to inactivation by H2O2 and decreased cellular ability for subsequent recovery. GPD responded in a similar fashion with oxidative treatment of another lung carcinoma cell line (A427) as well as normal lung tissue from human and rat. These findings indicate that the cellular thiol redox status can be important in determining GPD enzymatic activity.

  16. Neonatal phosphate nutrition alters in vivo and in vitro satellite cell activity in pigs.

    PubMed

    Alexander, Lindsey S; Seabolt, Brynn S; Rhoads, Robert P; Stahl, Chad H

    2012-06-01

    Satellite cell activity is necessary for postnatal skeletal muscle growth. Severe phosphate (PO(4)) deficiency can alter satellite cell activity, however the role of neonatal PO(4) nutrition on satellite cell biology remains obscure. Twenty-one piglets (1 day of age, 1.8 ± 0.2 kg BW) were pair-fed liquid diets that were either PO(4) adequate (0.9% total P), supra-adequate (1.2% total P) in PO(4) requirement or deficient (0.7% total P) in PO(4) content for 12 days. Body weight was recorded daily and blood samples collected every 6 days. At day 12, pigs were orally dosed with BrdU and 12 h later, satellite cells were isolated. Satellite cells were also cultured in vitro for 7 days to determine if PO(4) nutrition alters their ability to proceed through their myogenic lineage. Dietary PO(4) deficiency resulted in reduced (P < 0.05) sera PO(4) and parathyroid hormone (PTH) concentrations, while supra-adequate dietary PO(4) improved (P < 0.05) feed conversion efficiency as compared to the PO(4) adequate group. In vivo satellite cell proliferation was reduced (P < 0.05) among the PO(4) deficient pigs, and these cells had altered in vitro expression of markers of myogenic progression. Further work to better understand early nutritional programming of satellite cells and the potential benefits of emphasizing early PO(4) nutrition for future lean growth potential is warranted.

  17. Toxicological assessment of selective pesticides towards plant growth promoting activities of phosphate solubilizing Pseudomonas aeruginosa.

    PubMed

    Ahemad, Munees; Khan, Mohammad Saghir

    2011-09-01

    The study was designed to assess the effect of selected pesticides (metribuzin, glyphosate, imidacloprid, thiamethoxam, hexaconazole, metalaxyl and kitazin) at the recommended and higher rates on plant growth promoting activities of Pseudomonas aeruginosa strain PS1 isolated from mustard (Brassica compestris) rhizosphere. The strain PS1 was specifically chosen owing to its substantial tolerance against pesticides, phosphate solubilization and considerable production of indole acetic acid, siderophores, exo-polysaccharides, HCN and ammonia. Plant growth promoting traits of the strain PS1 decreased consistently as the concentrations of each pesticide was increased from the recommended dose to the higher ones. Generally, the maximum toxicity to plant growth promoting traits was displayed by pesticides at three times the recommended field rate. However, the effect on the plant growth promoting activities of the P. aeruginosa strain PS1 at the recommended dose of each pesticide was less hazardous. This study revealed an additional aspect of the toxicological mechanisms of the pesticides through which they suppress the plant growth.

  18. Effectiveness of phosphate removal during anaerobic digestion of waste activated sludge by dosing iron(III).

    PubMed

    Cheng, Xiang; Wang, Jue; Chen, Bing; Wang, Yu; Liu, Jiaqi; Liu, Lubo

    2017-05-15

    Phosphate-Fe(II) precipitation induced by Fe(III) reduction during the anaerobic digestion of excess activated sludge was investigated for the removal of phosphorus and its possible recovery. The experiments were conducted with three Fe(III) sources at 35 °C and 55 °C. The results show that ferrihydrite-Fe(III) was effectively reduced during the anaerobic sludge digestion by 63% and 96% under mesophilic and thermophilic conditions, respectively. Whereas FeCl3-Fe(III) was only mesophilically reducible and the reduction of hematite-Fe(III) was unnoticeable at either temperature. Efficient precipitation of vivianite was not observed although high saturation index values, e.g., >14 (activity reduction not considered), had been reached. This reveals the complexity of vivianite precipitation in anaerobic digestion systems; for example, Fe(II) complexation and organic interference could not be ignored. With ferrihydrite amendments at a Fe/TP of 1.5, methane production from sludge digestion was reduced by 35.1% at 35 °C, and was unaffected when the digestion temperature went up to 55 °C. But, acidic FeCl3 severely inhibited the methane production and consequently the sludge biomass degradation.

  19. Preliminary evidence for biologic activity of toceranib phosphate (Palladia(®)) in solid tumours.

    PubMed

    London, C; Mathie, T; Stingle, N; Clifford, C; Haney, S; Klein, M K; Beaver, L; Vickery, K; Vail, D M; Hershey, B; Ettinger, S; Vaughan, A; Alvarez, F; Hillman, L; Kiselow, M; Thamm, D; Higginbotham, M L; Gauthier, M; Krick, E; Phillips, B; Ladue, T; Jones, P; Bryan, J; Gill, V; Novasad, A; Fulton, L; Carreras, J; McNeill, C; Henry, C; Gillings, S

    2012-09-01

    The purpose of this study was to provide an initial assessment of the potential biologic activity of toceranib phosphate (Palladia®, Pfizer Animal Health, Madison, NJ, USA) in select solid tumours in dogs. Cases in which toceranib was used to treat dogs with apocrine gland anal sac adenocarcinoma (AGASACA), metastatic osteosarcoma (OSA), thyroid carcinoma, head and neck carcinoma and nasal carcinoma were included. Clinical benefit (CB) was observed in 63/85 (74%) dogs including 28/32 AGASACA [8 partial response (PR), 20 stable disease (SD)], 11/23 OSAs (1 PR and 10 SD), 12/15 thyroid carcinomas (4 PR and 8 SD), 7/8 head and neck carcinomas [1 complete response (CR), 5 PR and 1 SD] and 5/7 (1 CR and 4 SD) nasal carcinomas. For dogs experiencing CB, the median dose of toceranib was 2.8 mg kg(-1) , 36/63 (58.7%) were dosed on a Monday/Wednesday/Friday basis and 47/63 (74.6%) were treated 4 months or longer. Although these data provide preliminary evidence that toceranib exhibits CB in dogs with certain solid tumours, future prospective studies are necessary to define its true activity.

  20. Abnormal high-energy phosphate molecule metabolism during regional brain activation in patients with bipolar disorder.

    PubMed

    Yuksel, C; Du, F; Ravichandran, C; Goldbach, J R; Thida, T; Lin, P; Dora, B; Gelda, J; O'Connor, L; Sehovic, S; Gruber, S; Ongur, D; Cohen, B M

    2015-09-01

    Converging evidence suggests bioenergetic abnormalities in bipolar disorder (BD). In the brain, phosphocreatine (PCr) acts a reservoir of high-energy phosphate (HEP) bonds, and creatine kinases (CK) catalyze the transfer of HEP from adenosine triphosphate (ATP) to PCr and from PCr back to ATP, at times of increased need. This study examined the activity of this mechanism in BD by measuring the levels of HEP molecules during a stimulus paradigm that increased local energy demand. Twenty-three patients diagnosed with BD-I and 22 healthy controls (HC) were included. Levels of phosphorus metabolites were measured at baseline and during visual stimulation in the occipital lobe using (31)P magnetic resonance spectroscopy at 4T. Changes in metabolite levels showed different patterns between the groups. During stimulation, HC had significant reductions in PCr but not in ATP, as expected. In contrast, BD patients had significant reductions in ATP but not in PCr. In addition, PCr/ATP ratio was lower at baseline in patients, and there was a higher change in this measure during stimulation. This pattern suggests a disease-related failure to replenish ATP from PCr through CK enzyme catalysis during tissue activation. Further studies measuring the CK flux in BD are required to confirm and extend this finding.

  1. Role of the pyridine nitrogen in pyridoxal 5'-phosphate catalysis: activity of three classes of PLP enzymes reconstituted with deazapyridoxal 5'-phosphate.

    PubMed

    Griswold, Wait R; Toney, Michael D

    2011-09-21

    Pyridoxal 5'-phosphate (PLP; vitamin B(6))-catalyzed reactions have been well studied, both on enzymes and in solution, due to the variety of important reactions this cofactor catalyzes in nitrogen metabolism. Three functional groups are central to PLP catalysis: the C4' aldehyde, the O3' phenol, and the N1 pyridine nitrogen. In the literature, the pyridine nitrogen has traditionally been assumed to be protonated in enzyme active sites, with the protonated pyridine ring providing resonance stabilization of carbanionic intermediates. This assumption is certainly correct for some PLP enzymes, but the structures of other active sites are incompatible with protonation of N1, and, consequently, these enzymes are expected to use PLP in the N1-unprotonated form. For example, aspartate aminotransferase protonates the pyridine nitrogen for catalysis of transamination, while both alanine racemase and O-acetylserine sulfhydrylase are expected to maintain N1 in the unprotonated, formally neutral state for catalysis of racemization and β-elimination. Herein, kinetic results for these three enzymes reconstituted with 1-deazapyridoxal 5'-phosphate, an isosteric analogue of PLP lacking the pyridine nitrogen, are compared to those for the PLP enzyme forms. They demonstrate that the pyridine nitrogen is vital to the 1,3-prototropic shift central to transamination, but not to reactions catalyzed by alanine racemase or O-acetylserine sulfhydrylase. Not all PLP enzymes require the electrophilicity of a protonated pyridine ring to enable formation of carbanionic intermediates. It is proposed that modulation of cofactor electrophilicity plays a central role in controlling reaction specificity in PLP enzymes.

  2. Multisite inhibition of Pinus pinea isocitrate lyase by phosphate.

    PubMed

    Ranaldi, F; Vanni, P; Giachetti, E

    2000-11-01

    Our results show that the phosphate ion is a nonlinear competitive inhibitor of Pinus pinea isocitrate lyase. In addition, this compound induces a sigmoidal response of the enzyme, which usually exhibits standard Michaelis-Menten kinetics. This peculiar behavior of P. pinea isocitrate lyase could be explained by a dimer (two-site) model, in which phosphate binds cooperatively, but the affinity of the vacant site for substrate (the magnesium-isocitrate complex) remains the same. As a result, the interaction of phosphate with free enzyme produces an inhibitor-enzyme-inhibitor species that is of significant importance in determining reaction rate; a possible regulatory role of the glyoxylate cycle by inorganic phosphate is suggested. The mode of phosphate inhibition is consistent with both the mechanism for magnesium ion activation of P. pinea isocitrate lyase and its site heterogeneity. Our results explain the cooperative effects observed by some authors in kinetic studies of isocitrate lyase carried out in phosphate buffers and also account for the higher K(m) values determined by using such assay systems. Phosphate buffer should be avoided in performing isocitrate lyase kinetics.

  3. Activity of Type I Methanotrophs Dominates under High Methane Concentration: Methanotrophic Activity in Slurry Surface Crusts as Influenced by Methane, Oxygen, and Inorganic Nitrogen.

    PubMed

    Duan, Yun-Feng; Reinsch, Sabine; Ambus, Per; Elsgaard, Lars; Petersen, Søren O

    2017-07-01

    Livestock slurry is a major source of atmospheric methane (CH), but surface crusts harboring methane-oxidizing bacteria (MOB) could mediate against CH emissions. This study examined conditions for CH oxidation by in situ measurements of oxygen (O) and nitrous oxide (NO), as a proxy for inorganic N transformations, in intact crusts using microsensors. This was combined with laboratory incubations of crust material to investigate the effects of O, CH, and inorganic N on CH oxidation, using CH to trace C incorporation into lipids of MOB. Oxygen penetration into the crust was 2 to 14 mm, confining the potential for aerobic CH oxidation to a shallow layer. Nitrous oxide accumulated within or below the zone of O depletion. With 10 ppmv CH there was no O limitation on CH oxidation at O concentrations as low as 2%, whereas CH oxidation at 10 ppmv CH was reduced at ≤5% O. As hypothesized, CH oxidation was in general inhibited by inorganic N, especially NO, and there was an interaction between N inhibition and O limitation at 10 ppmv CH, as indicated by consistently stronger inhibition of CH oxidation by NH and NO at 3% compared with 20% O. Recovery of C in phospholipid fatty acids suggested that both Type I and Type II MOB were active, with Type I dominating high-concentration CH oxidation. Given the structural heterogeneity of crusts, CH oxidation activity likely varies spatially as constrained by the combined effects of CH, O, and inorganic N availability in microsites. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  4. The role of phosphates in chemical evolution.

    NASA Technical Reports Server (NTRS)

    Ponnamperuma, C.; Chang, S.

    1971-01-01

    The hypohydrous thermal reaction between inorganic phosphates and nucleoside was investigated. The products of the reactions have been identified, and an attempt has been made to determine the mechanism. It was found that orthophosphates can be readily converted into condensed phosphates which are effective phosphorylating agents. Thermal polymerization of inorganic orthophosphates at moderate temperature as a general source of polyphosphates might have provided efficient phosphorylation and condensing agents for primordial syntheses.

  5. Mitochondrial creatine kinase activity and phosphate shuttling are acutely regulated by exercise in human skeletal muscle.

    PubMed

    Perry, Christopher G R; Kane, Daniel A; Herbst, Eric A F; Mukai, Kazutaka; Lark, Daniel S; Wright, David C; Heigenhauser, George J F; Neufer, P Darrell; Spriet, Lawrence L; Holloway, Graham P

    2012-11-01

    Energy transfer between mitochondrial and cytosolic compartments is predominantly achieved by creatine-dependent phosphate shuttling (PCr/Cr) involving mitochondrial creatine kinase (miCK). However, ADP/ATP diffusion through adenine nucleotide translocase (ANT) and voltage-dependent anion carriers (VDACs) is also involved in this process. To determine if exercise alters the regulation of this system, ADP-stimulated mitochondrial respiratory kinetics were assessed in permeabilized muscle fibre bundles (PmFBs) taken from biopsies before and after 2 h of cycling exercise (60% ) in nine lean males. Concentrations of creatine (Cr) and phosphocreatine (PCr) as well as the contractile state of PmFBs were manipulated in situ. In the absence of contractile signals (relaxed PmFBs) and miCK activity (no Cr), post-exercise respiratory sensitivity to ADP was reduced in situ (up to 126% higher apparent K(m) to ADP) suggesting inhibition of ADP/ATP diffusion between matrix and cytosolic compartments (possibly ANT and VDACs). However this effect was masked in the presence of saturating Cr (no effect of exercise on ADP sensitivity). Given that the role of ANT is thought to be independent of Cr, these findings suggest ADP/ATP, but not PCr/Cr, cycling through the outer mitochondrial membrane (VDACs) may be attenuated in resting muscle after exercise. In contrast, in contracted PmFBs, post-exercise respiratory sensitivity to ADP increased with miCK activation (saturating Cr; 33% lower apparent K(m) to ADP), suggesting prior exercise increases miCK sensitivity in situ. These observations demonstrate that exercise increases miCK-dependent respiratory sensitivity to ADP, promoting mitochondrial-cytosolic energy exchange via PCr/Cr cycling, possibly through VDACs. This effect may mask an underlying inhibition of Cr-independent ADP/ATP diffusion. This enhanced regulation of miCK-dependent phosphate shuttling may improve energy homeostasis through more efficient coupling of oxidative

  6. Structural definition of the active site and catalytic mechanism of 3,4-dihydroxy-2-butanone-4-phosphate synthase.

    PubMed

    Liao, Der-Ing; Zheng, Ya-Jun; Viitanen, Paul V; Jordan, Douglas B

    2002-02-12

    X-ray crystal structures of L-3,4-dihydroxy-2-butanone-4-phosphate synthase from Magnaporthe grisea are reported for the E-SO(4)(2-), E-SO(4)(2-)-Mg(2+), E-SO(4)(2)(-)-Mn(2+), E-SO(4)(2)(-)-Mn(2+)-glycerol, and E-SO(4)(2)(-)-Zn(2+) complexes with resolutions that extend to 1.55, 0.98, 1.60, 1.16, and 1.00 A, respectively. Active-site residues of the homodimer are fully defined. The structures were used to model the substrate ribulose 5-phosphate in the active site with the phosphate group anchored at the sulfate site and the placement of the ribulose group guided by the glycerol site. The model includes two Mg(2+) cations that bind to the oxygen substituents of the C2, C3, C4, and phosphate groups of the substrate, the side chains of Glu37 and His153, and water molecules. The position of the metal cofactors and the substrate's phosphate group are further stabilized by an extensive hydrogen-bond and salt-bridge network. On the basis of their proximity to the substrate's reaction participants, the imidazole of an Asp99-His136 dyad from one subunit, the side chains of the Asp41, Cys66, and Glu174 residues from the other subunit, and Mg(2+)-activated water molecules are proposed to serve specific roles in the catalytic cycle as general acid-base functionalities. The model suggests that during the 1,2-shift step of the reaction, the substrate's C3 and C4 hydroxyl groups are cis to each other. A cis transition state is calculated to have an activation barrier that is 2 kcal/mol greater than that of the trans transition state in the absence of the enzyme.

  7. Structural definition of the active site and catalytic mechanism of 3,4-dihydroxy-2-butanone 4-phosphate synthase

    SciTech Connect

    Liao, D.-I.; Zheng, Y.-J.; Viitanen, P.V.; Jordan, D.B.

    2010-03-08

    X-ray crystal structures of L-3,4-dihydroxy-2-butanone-4-phosphate synthase from Magnaporthe grisea are reported for the E-SO{sub 4}{sup 2-}, E-{sub 4}{sup 2-}-Mg{sup 2+}, E-SO{sub 4}{sup 2-}-Mn{sup 2+}, E-SO{sub 4}{sup 2-}-Mn{sup 2+}-glycerol, and E-SO{sub 4}{sup 2-}-Zn{sup 2+} complexes with resolutions that extend to 1.55, 0.98, 1.60, 1.16, and 1.00 {angstrom}, respectively. Active-site residues of the homodimer are fully defined. The structures were used to model the substrate ribulose 5-phosphate in the active site with the phosphate group anchored at the sulfate site and the placement of the ribulose group guided by the glycerol site. The model includes two Mg{sup 2+} cations that bind to the oxygen substituents of the C2, C3, C4, and phosphate groups of the substrate, the side chains of Glu37 and His153, and water molecules. The position of the metal cofactors and the substrate's phosphate group are further stabilized by an extensive hydrogen-bond and salt-bridge network. On the basis of their proximity to the substrate's reaction participants, the imidazole of an Asp99-His136 dyad from one subunit, the side chains of the Asp41, Cys66, and Glu174 residues from the other subunit, and Mg{sup 2+}-activated water molecules are proposed to serve specific roles in the catalytic cycle as general acid-base functionalities. The model suggests that during the 1,2-shift step of the reaction, the substrate's C3 and C4 hydroxyl groups are cis to each other. A cis transition state is calculated to have an activation barrier that is 2 kcal/mol greater than that of the trans transition state in the absence of the enzyme.

  8. Cysteine-S-conjugate beta-lyase activity and pyridoxal phosphate binding site of onion alliin lyase.

    PubMed

    Kitamura, N; Shimomura, N; Iseki, J; Honma, M; Chiba, S; Tahara, S; Mizutani, J

    1997-08-01

    Purification of onion alliin lyase gave two fractions by cation exchange chromatography. Both fractions showed the comparable high catalytic activity of cysteine-S-conjugate beta-lyase with that of alliin lyase using S-(2-chloro-6-nitrophenyl)-L-cysteine and alliin, S-allyl-L-cysteine sulfoxide as substrates. All the active substrates tested with onion alliin lyase were also active to the cysteine-S-conjugate beta-lyase of Mucor javanicus, but the catalytic activity of the Mucor enzyme was lower for all the substrates. The pyridoxal phosphate binding site of the onion alliin lyase was identified as Lys 285 in the amino acid sequence deduced from cDNA which has been reported. This lysine was conserved in all the sequences from the alliin lyase cDNAs, while similarity was not found between the sequences around pyridoxal phosphate binding sites of both the onion alliin lyase and the Mucor cysteine-S-conjugate beta-lyase.

  9. Inactivation of the AMP-activated protein kinase by glucose in cardiac myocytes: a role for the pentose phosphate pathway.

    PubMed

    Tabidi, Ikhlass; Saggerson, David

    2012-06-01

    Incubation of adult rat cardiac myocytes with increasing glucose concentrations decreased phosphorylation (αThr172) and activity of AMPK (AMP-activated protein kinase). The effect could be demonstrated without measurable changes in adenine nucleotide contents. The glucose effect was additive to the decrease in AMPK activity caused by insulin, was attenuated by adrenaline, was not mimicked by glucose analogues, lactate or pyruvate and was not due to changes in myocyte glycogen content. AMPK activity was decreased by xylitol and PMS (phenazine methosulfate) and was increased by the glucose-6-phosphate dehydrogenase inhibitor DHEA (dehydroepiandrosterone) and by thiamine. PMS and DHEA respectively, increased and decreased CO2 formation by the PPP (pentose phosphate pathway). AMPK activity was inversely related to the myocyte content of Xu5P (xylulose 5-phosphate), an intermediate of the non-oxidative arm of the PPP. Endothall, an inhibitor of PP2A (protein phosphatase 2A), abolished the glucose effect on AMPK activity. Further studies are needed to define the 'active component' that mediates the glucose effect and whether its site of action is PP2A.

  10. Sphingosine-1-phosphate lyase downregulation promotes colon carcinogenesis through STAT3-activated microRNAs.

    PubMed

    Degagné, Emilie; Pandurangan, Ashok; Bandhuvula, Padmavathi; Kumar, Ashok; Eltanawy, Abeer; Zhang, Meng; Yoshinaga, Yuko; Nefedov, Mikhail; de Jong, Pieter J; Fong, Loren G; Young, Stephen G; Bittman, Robert; Ahmedi, Yasmin; Saba, Julie D

    2014-12-01

    Growing evidence supports a link between inflammation and cancer; however, mediators of the transition between inflammation and carcinogenesis remain incompletely understood. Sphingosine-1-phosphate (S1P) lyase (SPL) irreversibly degrades the bioactive sphingolipid S1P and is highly expressed in enterocytes but downregulated in colon cancer. Here, we investigated the role of SPL in colitis-associated cancer (CAC). We generated mice with intestinal epithelium-specific Sgpl1 deletion and chemically induced colitis and tumor formation in these animals. Compared with control animals, mice lacking intestinal SPL exhibited greater disease activity, colon shortening, cytokine levels, S1P accumulation, tumors, STAT3 activation, STAT3-activated microRNAs (miRNAs), and suppression of miR-targeted anti-oncogene products. This phenotype was attenuated by STAT3 inhibition. In fibroblasts, silencing SPL promoted tumorigenic transformation through a pathway involving extracellular transport of S1P through S1P transporter spinster homolog 2 (SPNS2), S1P receptor activation, JAK2/STAT3-dependent miR-181b-1 induction, and silencing of miR-181b-1 target cylindromatosis (CYLD). Colon biopsies from patients with inflammatory bowel disease revealed enhanced S1P and STAT3 signaling. In mice with chemical-induced CAC, oral administration of plant-type sphingolipids called sphingadienes increased colonic SPL levels and reduced S1P levels, STAT3 signaling, cytokine levels, and tumorigenesis, indicating that SPL prevents transformation and carcinogenesis. Together, our results suggest that dietary sphingolipids can augment or prevent colon cancer, depending upon whether they are metabolized to S1P or promote S1P metabolism through the actions of SPL.

  11. Heterodimer formation and activity in the human enzyme galactose-1-phosphate uridylyltransferase.

    PubMed Central

    Elsevier, J P; Wells, L; Quimby, B B; Fridovich-Keil, J L

    1996-01-01

    One of the fundamental questions concerning expression and function of dimeric enzymes involves the impact of naturally occurring mutations on subunit assembly and heterodimer activity. This question is of particular interest for the human enzyme galactose-l-phosphate uridylyl-transferase (GALT), impairment of which results in the inherited metabolic disorder galactosemia, because many if not most patients studied to date are compound heterozygotes rather than true molecular homozygotes. Furthermore, the broad range of phenotypic severity observed in these patients raises the possibility that allelic combination, not just allelic constitution, may play some role in determining outcome. In the work described herein, we have selected two distinct naturally occurring null mutations of GALT, Q188R and R333W, and asked the questions (i) what are the impacts of these mutations on subunit assembly, and (ii) if heterodimers do form, are they active? To answer these questions, we have established a yeast system for the coexpression of epitope-tagged alleles of human GALT and investigated both the extent of specific GALT subunit interactions and the activity of defined heterodimer pools. We have found that both homodimers and heterodimers do form involving each of the mutant subunits tested and that both heterodimer pools retain substantial enzymatic activity. These results are significant not only in terms of their implications for furthering our understanding of galactosemia and GALT holoenzyme structure-function relationships but also because the system described may serve as a model for similar studies of other complexes composed of multiple subunits. Images Fig. 1 Fig. 4 Fig. 6 PMID:8692963

  12. Sphingosine-1-phosphate lyase downregulation promotes colon carcinogenesis through STAT3-activated microRNAs

    PubMed Central

    Degagné, Emilie; Pandurangan, Ashok; Bandhuvula, Padmavathi; Kumar, Ashok; Eltanawy, Abeer; Zhang, Meng; Yoshinaga, Yuko; Nefedov, Mikhail; de Jong, Pieter J.; Fong, Loren G.; Young, Stephen G.; Bittman, Robert; Ahmedi, Yasmin; Saba, Julie D.

    2014-01-01

    Growing evidence supports a link between inflammation and cancer; however, mediators of the transition between inflammation and carcinogenesis remain incompletely understood. Sphingosine-1-phosphate (S1P) lyase (SPL) irreversibly degrades the bioactive sphingolipid S1P and is highly expressed in enterocytes but downregulated in colon cancer. Here, we investigated the role of SPL in colitis-associated cancer (CAC). We generated mice with intestinal epithelium-specific Sgpl1 deletion and chemically induced colitis and tumor formation in these animals. Compared with control animals, mice lacking intestinal SPL exhibited greater disease activity, colon shortening, cytokine levels, S1P accumulation, tumors, STAT3 activation, STAT3-activated microRNAs (miRNAs), and suppression of miR-targeted anti-oncogene products. This phenotype was attenuated by STAT3 inhibition. In fibroblasts, silencing SPL promoted tumorigenic transformation through a pathway involving extracellular transport of S1P through S1P transporter spinster homolog 2 (SPNS2), S1P receptor activation, JAK2/STAT3-dependent miR-181b-1 induction, and silencing of miR-181b-1 target cylindromatosis (CYLD). Colon biopsies from patients with inflammatory bowel disease revealed enhanced S1P and STAT3 signaling. In mice with chemical-induced CAC, oral administration of plant-type sphingolipids called sphingadienes increased colonic SPL levels and reduced S1P levels, STAT3 signaling, cytokine levels, and tumorigenesis, indicating that SPL prevents transformation and carcinogenesis. Together, our results suggest that dietary sphingolipids can augment or prevent colon cancer, depending upon whether they are metabolized to S1P or promote S1P metabolism through the actions of SPL. PMID:25347472

  13. Amino acid dependent formation of phosphate anhydrides in water mediated by carbonyl sulfide.

    PubMed

    Leman, Luke J; Orgel, Leslie E; Ghadiri, M Reza

    2006-01-11

    Carbonyl sulfide (COS), a component of volcanic gas emissions and interstellar gas clouds, is shown to be an efficient condensing agent in the context of phosphate chemistry in aqueous solutions. We report that high-energy aminoacyl-phosphate anhydrides and aminoacyl adenylates are generated in solutions containing amino acids, COS, and the corresponding phosphate molecule. We further show that the mixed anhydrides of amino acids and inorganic phosphate are phosphorylating agents, producing pyrophosphate in better than 30% yield in the presence of Ca2+ precipitates. The amino acid dependent activations of phosphate reported here, which occur in parallel with the production of peptides, suggest that these two reactions may have shared a common intermediate on the prebiotic Earth.

  14. Selection of pecan shell-based activated carbons for removal of organic and inorganic impurities from water.

    PubMed

    Niandou, Mohamed A S; Novak, Jeffrey M; Bansode, Rishipal R; Yu, Jianmei; Rehrah, Djaafar; Ahmedna, Mohamed

    2013-01-01

    Activated carbons are a byproduct from pyrolysis and have value as a purifying agent. The effectiveness of activated carbons is dependent on feedstock selection and pyrolysis conditions that modify their surface properties. Therefore, pecan shell-based activated carbons (PSACs) were prepared by soaking shells in 50% (v/v) HPO or 25 to 50% of KOH-NaHCO followed by pyrolysis at 400 to 700°C under a N atmosphere. Physically activated PSACs were produced by pyrolysis at 700°C under N followed by activation with steam or CO at 700 to 900°C. Physicochemical, surface, and adsorption properties of the PSACs were compared with two commercially available activated carbons. The average mass yield of PSACs with respect to the initial mass of the biomass was about 20 and 34% for physically activated and chemically activated carbons, respectively. Acid-activated carbons exhibited higher surface area, higher bulk density, and lower ash content compared with steam- or CO-activated carbons and the two commercial products. Base activation led to the development of biochar with moderate to high surface area with surface charges suitable for adsorption of anionic species. Regardless of the activation method, PSACs had high total surface area ranging from 400 to 1000 m g, better pore size distribution, and more surface charges than commercial samples. Our results also showed that PSACs were effective in removing inorganic contaminants such as Cu and NO as well as organic contaminants such as atrazine and metolachlor. This study showed that pyrolysis conditions and activation had a large influence on the PSAC's surface characteristics, which can limit its effectiveness as a custom sorbent for targeted water contaminants.

  15. Changes in polyamines, inorganic ions and glutamine synthetase activity in response to nitrogen availability and form in red spruce (Picea rubens)

    Treesearch

    Michelle J. Serapiglia; Rakesh Minocha; Subhash C. Minocha

    2008-01-01

    We analyzed effects of nitrogen availability and form on growth rates, concentrations of polyamines and inorganic ions and glutamine synthetase activity in in-vitro-cultured red spruce (Picea rubens Sarg.) cells. Growth rates, concentrations of polyamines and glutamine synthetase activity declined when either the amount of nitrate or the total amount...

  16. Treatment of Hypophosphatemic Rickets with Phosphate and Active Vitamin D in Japan: A Questionnaire-based Survey

    PubMed Central

    Fujiwara, Makoto; Namba, Noriyuki; Ozono, Keiichi; Arisaka, Osamu; Yokoya, Susumu

    2013-01-01

    Hereditary hypophosphatemic rickets represented by X-linked hypophosphatemic rickets (XLH) is a rare disorder characterized by hypophosphatemia, elevated alkaline phosphatase (ALP) and undermineralization of bone. Active vitamin D and phosphate are administered to correct hypophosphatemia and elevation of ALP. Overtreatment with phosphate leads to secondary hyperparathyroidism, and a large dose of active vitamin D has a risk of hypercalciuria. To understand the situation concerning treatment of patients with hereditary hypophosphatemic rickets in Japan, we conducted a questionnaire survey of pediatric endocrinologists. Answers were obtained from 53 out of 68 hospitals where the pediatric endocrinologists worked. One hundred and thirty-five patients were treated in 28 hospitals during November 2009 and May 2010; 126 patients suffered from hereditary hypophosphatemic rickets, and 9 had hypophosphatemia caused by other miscellaneous reasons. The distribution of patient age was as follows: 27 (21%) were between 6 mo and 6 yr of age, 39 (31%) were between 6 and 12 yr of age, and 60 (48%) were more than 12 yr of age. Active vitamin D was given to 123 patients, and phosphate was given to 106 patients. As for the dose of phosphorus, 37.2–58.1 mg/kg/d was given divided into 2 to 6 aliquots. There were various control targets of treatment, including serum phosphate, serum ALP, rachitic change, urinary Ca/Cr, parathyroid hormone and growth. It is very important to avoid side effects of these treatments. No evidence is available about the optimal dose of phosphate or number of administrations in the treatment of patients with hypophosphatemic rickets. Although there is a recommendation for clinical management of patients with hypophosphatemic rickets, we should set a clinical guideline for it in Japan. PMID:23966755

  17. Treatment of Hypophosphatemic Rickets with Phosphate and Active Vitamin D in Japan: A Questionnaire-based Survey.

    PubMed

    Fujiwara, Makoto; Namba, Noriyuki; Ozono, Keiichi; Arisaka, Osamu; Yokoya, Susumu

    2013-01-01

    Hereditary hypophosphatemic rickets represented by X-linked hypophosphatemic rickets (XLH) is a rare disorder characterized by hypophosphatemia, elevated alkaline phosphatase (ALP) and undermineralization of bone. Active vitamin D and phosphate are administered to correct hypophosphatemia and elevation of ALP. Overtreatment with phosphate leads to secondary hyperparathyroidism, and a large dose of active vitamin D has a risk of hypercalciuria. To understand the situation concerning treatment of patients with hereditary hypophosphatemic rickets in Japan, we conducted a questionnaire survey of pediatric endocrinologists. Answers were obtained from 53 out of 68 hospitals where the pediatric endocrinologists worked. One hundred and thirty-five patients were treated in 28 hospitals during November 2009 and May 2010; 126 patients suffered from hereditary hypophosphatemic rickets, and 9 had hypophosphatemia caused by other miscellaneous reasons. The distribution of patient age was as follows: 27 (21%) were between 6 mo and 6 yr of age, 39 (31%) were between 6 and 12 yr of age, and 60 (48%) were more than 12 yr of age. Active vitamin D was given to 123 patients, and phosphate was given to 106 patients. As for the dose of phosphorus, 37.2-58.1 mg/kg/d was given divided into 2 to 6 aliquots. There were various control targets of treatment, including serum phosphate, serum ALP, rachitic change, urinary Ca/Cr, parathyroid hormone and growth. It is very important to avoid side effects of these treatments. No evidence is available about the optimal dose of phosphate or number of administrations in the treatment of patients with hypophosphatemic rickets. Although there is a recommendation for clinical management of patients with hypophosphatemic rickets, we should set a clinical guideline for it in Japan.

  18. Phosphate salts

    MedlinePlus

    ... taken by mouth or used as enemas. Indigestion. Aluminum phosphate and calcium phosphate are FDA-permitted ingredients ... Phosphate salts containing sodium, potassium, aluminum, or calcium are LIKELY SAFE for most people when taken by mouth short-term, when sodium phosphate is inserted into the ...

  19. Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles

    PubMed Central

    Chen, Chen; Weir, Michael D.; Cheng, Lei; Lin, Nancy; Lin-Gibson, Sheng; Chow, Laurence C.; Zhou, Xuedong; Xu, Hockin H. K.

    2015-01-01

    Objectives Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties. Methods Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4. Results Adding 5% DMADDM and 10–40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p > 0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6–10 folds. Significance Bonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was “smart” and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent

  20. Anticancer activity of drug-loaded calcium phosphate nanocomposites against human osteosarcoma.

    PubMed

    Son, Kyoung Dan; Kim, Young-Jin

    2017-01-01

    Calcium phosphate (CaP) based nanoparticles are considered to be ideal drug carriers for delivery of anticancer drugs because of their excellent biocompatibility and pH responsiveness. However, CaP nanoparticles have the problems of limited drug load capacity, initial burst release, and short-term release. Thus, we prepared the CaP nanocomposites containing anticancer drug such as caffeic acid (CA-NP), chlorogenic acid (CG-NP), or cisplatin (CP-NP) in the presence of alginate as a polymer template to control the release rate of drugs. The drug-loaded CaP nanocomposites exhibited spherical shape with a size of under 100 nm and the size of nanocomposites was hardly affected by the addition of drug. UV-visible spectroscopic analysis confirmed the insertion of drug into the CaP nanocomposites. These nanocomposites showed an initial burst release of drug, followed by a prolonged release, in which the release profile of drugs was depended on the solution pH. In addition, the drug-loaded CaP nanocomposites revealed anticancer activity on human osteosarcoma in a manner dependent on concentration of drugs and time. The drug-loaded CaP nanocomposites can contribute to the development of a new generation of controlled drug release carriers for chemotherapy of cancers.

  1. Control of glycolytic flux in Zymomonas mobilis by glucose 6-phosphate dehydrogenase activity

    SciTech Connect

    Snoep, J.L. |; Arfman, N.; Yomano, L.P.; Ingram, L.O.; Westerhoff, H.V.; Conway, T.

    1996-07-20

    Alycolytic genes in Zymomonas mobilis are highly expressed and constitute half of the cytoplasmic protein. The first four genes (glf, zwf, edd, glk) in this pathway form an operon encoding a glucose permease, glucose 6-phosphate dehydrogenase (G6-P dehydrogenase), 6-phosphogluconate dehydratase, and glucokinase, respectively. Each gene was overexpressed from a tac promoter to investigate the control of glycolysis during the early stages of batch fermentation when flux (qCO{sub 2}) is highest. Almost half of flux control appears to reside with G6-P dehydrogenase (C{sub G6-P dehydrogenase}{sup J} = 0.4). Although Z. mobilis exhibits one of the highest rates of glycolysis known, recombinants with elevated G6-P dehydrogenase had a 10% to 13% higher glycolytic flux than the native organism. A small increase in flux was also observed for recombinants expressing glf. Results obtained did not allow a critical evaluation of glucokinase and this enzyme may also represent an important control point. 6-Phosphogluconate dehydratase appears to be saturating at native levels. With constructs containing the full operon, growth rate and flux were both reduced, complicating interpretations. However, results obtained were also consistent with G6-P dehydrogenase as a primary site of control. Flux was 17% higher in operon constructs which exhibited a 17% increase in G6-P dehydrogenase specific activity, relative to the average of other operon constructs which contain a frameshift mutation in zwf.

  2. The activity of liver alcohol dehydrogenase with nicotinamide–adenine dinucleotide phosphate as coenzyme

    PubMed Central

    Dalziel, K.; Dickinson, F. M.

    1965-01-01

    1. The separation of nucleotide impurities from commercial NADP preparations by chromatography is described. All the preparations studied contained 0·1–0·2% of NAD. 2. The activity of pure crystalline liver alcohol dehydrogenase with NADP as coenzyme has been confirmed. Initial-rate data are reported for the reaction at pH 6·0 and 7·0 with ethanol and acetaldehyde as substrates. With NADP and NADPH2 of high purity, the maximal specific rates were similar to those obtained with NAD and NADH2, but the Michaelis constants for the former coenzymes were much greater than those for the latter. 3. The oxidation of ethanol by NADP is greatly inhibited by NADH2, and this accounts for low values of certain initial-rate parameters obtained with commercial NADP preparations containing NAD. The kinetics of the inhibition are consistent with competitive inhibition in a compulsory-order mechanism. 4. Initial-rate data with NAD and NADPH2 do not conform to the requirements of the mechanism proposed by Theorell & Chance (1951), in contrast with results previously obtained with NAD and NADH2. The possibility that the deviations are due to competing nucleotide impurity in the oxidized coenzyme cannot be excluded. The data show that the enzyme reacts more slowly with, and has a smaller affinity for, NADP and NADPH2 than NAD and NADH2. 5. Phosphate behaves as a competitive inhibitor towards NADP. PMID:14340079

  3. Nicotinic acid-adenine dinucleotide phosphate activates the skeletal muscle ryanodine receptor.

    PubMed Central

    Hohenegger, Martin; Suko, Josef; Gscheidlinger, Regina; Drobny, Helmut; Zidar, Andreas

    2002-01-01

    Calcium is a universal second messenger. The temporal and spatial information that is encoded in Ca(2+)-transients drives processes as diverse as neurotransmitter secretion, axonal outgrowth, immune responses and muscle contraction. Ca(2+)-release from intracellular Ca(2+) stores can be triggered by diffusible second messengers like Ins P (3), cyclic ADP-ribose or nicotinic acid-adenine dinucleotide phosphate (NAADP). A target has not yet been identified for the latter messenger. In the present study we show that nanomolar concentrations of NAADP trigger Ca(2+)-release from skeletal muscle sarcoplasmic reticulum. This was due to a direct action on the Ca(2+)-release channel/ryanodine receptor type-1, since in single channel recordings, NAADP increased the open probability of the purified channel protein. The effects of NAADP on Ca(2+)-release and open probability of the ryanodine receptor occurred over a similar concentration range (EC(50) approximately 30 nM) and were specific because (i) they were blocked by Ruthenium Red and ryanodine, (ii) the precursor of NAADP, NADP, was ineffective at equimolar concentrations, (iii) NAADP did not affect the conductance and reversal potential of the ryanodine receptor. Finally, we also detected an ADP-ribosyl cyclase activity in the sarcoplasmic reticulum fraction of skeletal muscle. This enzyme was not only capable of synthesizing cyclic GDP-ribose but also NAADP, with an activity of 0.25 nmol/mg/min. Thus, we conclude that NAADP is generated in the vicinity of type 1 ryanodine receptor and leads to activation of this ion channel. PMID:12102654

  4. Effect of phosphate activating group on oligonucleotide formation on montmorillonite: the regioselective formation of 3',5'-linked oligoadenylates

    NASA Technical Reports Server (NTRS)

    Prabahar, K. J.; Cole, T. D.; Ferris, J. P.

    1994-01-01

    The effects of amine structure on the montmorillonite-catalyzed oligomerization of the 5'-phosphoramidates of adenosine are investigated. 4-Aminopyridine derivatives yielded oligoadenylates as long as dodecamers with a regioselectivity for 3',5'-phosphodiester bond formation averaging 88%. Linear and cyclic oligomers are obtained and no A5'ppA-containing products are detected. Oligomers as long as the hexanucleotide are obtained using 2-aminobenzimidazole as the activating group. A predominance of pA2'pA is detected in the dimer fraction along with cyclic 3',5'-trimer; no A5'ppA-containing oligomers were detected. Little or no oligomer formation was observed when morpholine, piperidine, pyrazole, 1,2,4-triazole, and 2-pyridone are used as phosphate-activating groups. The effects of the structure of the phosphate activating group on the oligomer structure and chain lengths are discussed.

  5. Effect of phosphate activating group on oligonucleotide formation on montmorillonite: the regioselective formation of 3',5'-linked oligoadenylates

    NASA Technical Reports Server (NTRS)

    Prabahar, K. J.; Cole, T. D.; Ferris, J. P.

    1994-01-01

    The effects of amine structure on the montmorillonite-catalyzed oligomerization of the 5'-phosphoramidates of adenosine are investigated. 4-Aminopyridine derivatives yielded oligoadenylates as long as dodecamers with a regioselectivity for 3',5'-phosphodiester bond formation averaging 88%. Linear and cyclic oligomers are obtained and no A5'ppA-containing products are detected. Oligomers as long as the hexanucleotide are obtained using 2-aminobenzimidazole as the activating group. A predominance of pA2'pA is detected in the dimer fraction along with cyclic 3',5'-trimer; no A5'ppA-containing oligomers were detected. Little or no oligomer formation was observed when morpholine, piperidine, pyrazole, 1,2,4-triazole, and 2-pyridone are used as phosphate-activating groups. The effects of the structure of the phosphate activating group on the oligomer structure and chain lengths are discussed.

  6. Effects of pH and inorganic salts on the adsorption of phenol from aqueous systems on activated decolorizing charcoal

    SciTech Connect

    Halhouli, K.A.; Darwish, N.A.; Al-Dhoon, N.M.

    1995-10-01

    An experimental investigation of the effects of pH and three inorganic salts (KCl, KI, and NaCl) on the adsorption isotherms of phenol (from a dilute aqueous solution) on activated charcoal was conducted. Each salt was studied at three different concentrations, i.e., 0.1, 0.01, and 0.005 M. The effect of pH (in the pH range 3 to 11) in the presence of KI, KCl, and NaCl was also investigated. The concentration of phenol in the aqueous systems studied ranged from 10 to 200 ppm. The temperature effect was also studied, and the resulting experimental equilibrium isotherms at 30, 40, and 55{degrees}C are well represented by Freundlich, Langmuir, and Redlich-Paterson isotherms. The relevant parameters for these isotherms are presented.

  7. New Advances in Nanotechnology-Based Diagnosis and Therapeutics for Breast Cancer: An Assessment of Active-Targeting Inorganic Nanoplatforms.

    PubMed

    Falagan-Lotsch, Priscila; Grzincic, Elissa M; Murphy, Catherine J

    2017-01-18

    Breast cancer is a major cause of suffering and mortality among women. Limitations in the current diagnostic methods and treatment approaches have led to new strategies to positively impact the survival rates and quality of life of breast cancer patients. Nanotechnology offers a real possibility of mitigating breast cancer mortality by early-stage cancer detection and more precise diagnosis as well as more effective treatments with minimal side effects. The current nanoplatforms approved for breast cancer therapeutics are based on passive tumor targeting using organic nanoparticles and have not provided the expected significant improvements in the clinic. In this review, we present the emerging approaches in breast cancer nanomedicine based on active targeting using versatile inorganic nanoplatforms with biomedical relevance, such as gold, silica, and iron oxide nanoparticles, as well as their efficacy in breast cancer imaging, drug and gene delivery, thermal therapy, combinational therapy, and theranostics in preclinical studies. The main challenges for clinical translation and perspectives are discussed.

  8. Arsenic, inorganic

    Integrated Risk Information System (IRIS)

    Arsenic , inorganic ; CASRN 7440 - 38 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  9. Osteoarthritis-associated basic calcium phosphate crystals activate membrane proximal kinases in human innate immune cells.

    PubMed

    Corr, Emma M; Cunningham, Clare C; Helbert, Laura; McCarthy, Geraldine M; Dunne, Aisling

    2017-02-07

    Osteoarthritis (OA) is a chronic debilitating joint disorder of particularly high prevalence in the elderly population. Intra-articular basic calcium phosphate (BCP) crystals are present in the majority of OA joints and are associated with severe degeneration. They are known to activate macrophages, synovial fibroblasts, and articular chondrocytes, resulting in increased cell proliferation and the production of pro-inflammatory cytokines and matrix metalloproteases (MMPs). This suggests a pathogenic role in OA by causing extracellular matrix degradation and subchondral bone remodelling. There are currently no disease-modifying drugs available for crystal-associated OA; hence, the aim of this study was to explore the inflammatory pathways activated by BCP crystals in order to identify potential therapeutic targets to limit crystal-induced inflammation. Primary human macrophages and dendritic cells were stimulated with BCP crystals, and activation of spleen tyrosine kinase (Syk), phosphoinositide-3 kinase (PI3K), and mitogen-activated protein kinases (MAPKs) was detected by immunoblotting. Lipopolysaccharide (LPS)-primed macrophages were pre-treated with inhibitors of Syk, PI3K, and MAPKs prior to BCP stimulation, and cytokine production was quantified by enzyme-linked immunosorbent assay (ELISA). Aa an alternative, cells were treated with synovial fluid derived from osteoarthritic knees in the presence or absence of BCP crystals, and gene induction was assessed by real-time polymerase chain reaction (PCR). We demonstrate that exposure of primary human macrophages and dendritic cells to BCP crystals leads to activation of the membrane-proximal tyrosine kinases Syk and PI3K. Furthermore, we show that production of the pro-inflammatory cytokines interleukin (IL)-1α and IL-1β and phosphorylation of downstream MEK and ERK MAPKs is suppressed following treatment with inhibitors of Syk or PI3K. Finally, we demonstrate that treatment of macrophages with BCP crystals

  10. Characterization of cytolytic neutrophil activation in vitro by amorphous hydrated calcium phosphate as a model of biomaterial inflammation.

    PubMed

    Edwards, Felicity C; Taheri, Amir; Dann, Sophie C; Dye, Julian F

    2011-03-01

    Calcium ions are utilized in biomolecular biomaterial design for osteomimetic scaffolds and as divalent cross-linking agents, typically for gelation of alginates, stabilisation of protein structure (e.g., fibrinogen) and enzyme activation (e.g., thrombin). Biological interactions with defined calcium phosphates (e.g., hydroxyapatite) are exploited for osteogenesis, although crystalline calcium phosphates (e.g., calcium pyrophosphate) stimulate inflammation. We found that the calcium concentration used in the manufacture of prototype dermal scaffolds made from fibrin/alginate composite was related to the inflammatory infiltration during in vivo integration. In investigating a cause for this inflammatory response, we have identified and characterized a cytolytic inflammatory effect of amorphous calcium phosphate (CaP) formed in physiological solutions, relevant to biomaterial biocompatibility. Isolated human neutrophils (Nφ) were incubated in phosphate-buffered saline with CaCl(2) ranging 2.5-20 mM total calcium. Nφ activation was assessed by morphology and integrin-β2 (CD18a) expression. Mediator release (Nφ-elastase, IL-8, and TNFα) was measured from both Nφ and whole blood cultures plus CaCl(2). CaP exposure increased CD18a expression over 1 h (maximal at 10 mM calcium/ phosphate) with concurrent phagocytosis, cytolysis, and Nφ-elastase release. CaCl(2) induced expression of IL-8 and TNFα in whole blood cultures. These results suggest that CaP formed from the resorption of calcium-containing biomaterials could induce inflammation and accelerate biomaterial degradation, driving further CaP release. This demonstrates a novel mechanism for biomaterial-induced inflammation. The in vitro system described could aid preclinical evaluation of novel biomaterial inflammatory potential. Copyright © 2011 Wiley Periodicals, Inc.

  11. Comparison of the adjuvant activity of aluminum hydroxide and calcium phosphate on the antibody response towards Bothrops asper snake venom.

    PubMed

    Olmedo, Hidekel; Herrera, María; Rojas, Leonardo; Villalta, Mauren; Vargas, Mariángela; Leiguez, Elbio; Teixeira, Catarina; Estrada, Ricardo; Gutiérrez, José María; León, Guillermo; Montero, Mavis L

    2014-01-01

    The adjuvanticity of aluminum hydroxide and calcium phosphate on the antibody response in mice towards the venom of the snake Bothrops asper was studied. It was found that, in vitro, most of the venom proteins are similarly adsorbed by both mineral salts, with the exception of some basic phospholipases A2, which are better adsorbed by calcium phosphate. After injection, the adjuvants promoted a slow release of the venom, as judged by the lack of acute toxicity when lethal doses of venom were administered to mice. Leukocyte recruitment induced by the venom was enhanced when it was adsorbed on both mineral salts; however, venom adsorbed on calcium phosphate induced a higher antibody response towards all tested HPLC fractions of the venom. On the other hand, co-precipitation of venom with calcium phosphate was the best strategy for increasing: (1) the capacity of the salt to couple venom proteins in vitro; (2) the venom ability to induce leukocyte recruitment; (3) phagocytosis by macrophages; and (4) a host antibody response. These findings suggest that the chemical nature is not the only one determining factor of the adjuvant activity of mineral salts.

  12. Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: spin coating vs electrochemical activation.

    PubMed

    Hernandez-Montelongo, J; Gallach, D; Naveas, N; Torres-Costa, V; Climent-Font, A; García-Ruiz, J P; Manso-Silvan, M

    2014-01-01

    Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering.

  13. Conjugated bile acids promote cholangiocarcinoma cell invasive growth through activation of sphingosine 1-phosphate receptor 2

    PubMed Central

    Liu, Runping; Zhao, Renping; Zhou, Xiqiao; Liang, Xiuyin; Campbell, Deanna JW; Zhang, Xiaoxuan; Zhang, Luyong; Shi, Ruihua; Wang, Guangji; Pandak, William M; Sirica, Alphonse E; Hylemon, Phillip B; Zhou, Huiping

    2014-01-01

    Cholangiocarcinoma (CCA) is an often fatal primary malignancy of the intra- and extrahepatic biliary tract that is commonly associated with chronic cholestasis and significantly elevated levels of primary and conjugated bile acids (CBAs), which are correlated with bile duct obstruction (BDO). BDO has also recently been shown to promote CCA progression. However, whereas there is increasing evidence linking chronic cholestasis and abnormal bile acid profiles to CCA development and progression, the specific mechanisms by which bile acids may be acting to promote cholangiocarcinogenesis and invasive biliary tumor growth have not been fully established. Recent studies have shown that CBAs, but not free bile acids, stimulate CCA cell growth, and that an imbalance in the ratio of free to CBAs may play an important role in the tumorigenesis of CCA. Also, CBAs are able to activate extracellular signal-regulated kinase (ERK)1/2- and phosphatidylinositol-3-kinase/protein kinase B (AKT)-signaling pathways through sphingosine 1-phosphate receptor 2 (S1PR2) in rodent hepatocytes. In the current study, we demonstrate S1PR2 to be highly expressed in rat and human CCA cells, as well as in human CCA tissues. We further show that CBAs activate the ERK1/2- and AKT-signaling pathways and significantly stimulate CCA cell growth and invasion in vitro. Taurocholate (TCA)-mediated CCA cell proliferation, migration, and invasion were significantly inhibited by JTE-013, a chemical antagonist of S1PR2, or by lentiviral short hairpin RNA silencing of S1PR2. In a novel organotypic rat CCA coculture model, TCA was further found to significantly increase the growth of CCA cell spheroidal/“duct-like” structures, which was blocked by treatment with JTE-013. Conclusion: Our collective data support the hypothesis that CBAs promote CCA cell-invasive growth through S1PR2. PMID:24700501

  14. Microbial Community Structure of Activated Sludge for Biosolubilization of Two Different Rock Phosphates.

    PubMed

    Xiao, Chunqiao; Wu, Xiaoyan; Liu, Tingting; Xu, Guang; Chi, Ruan

    2016-12-16

    A microbial consortium was directly taken from activated sludge and was used to solubilize rock phosphates (RPs) in a lab-scale bioreactor in this study. Results showed that the microbial consortium could efficiently release soluble phosphorus (P) from the RPs, and during 30-day incubation, it grew well in the bioreactor and reduced the pH of the solutions. The biosolubilization process was also illustrated by the observation of scanning electron microscopy combined with an energy dispersive X-ray spectroscopy (SEM-EDX), which showed an obvious corrosion on the ore surfaces, and most elements were removed from the ore samples. The analysis of microbial community structure by Illumina 16S ribosomal RNA (rRNA) gene and 18S rRNA gene MiSeq sequencing reflected different microbial diversity and richness in the solutions added with different ore samples. A lower richness and diversity of bacteria but a higher richness and diversity of fungi occurred in the solution added with ore sample 1 compared to that of in the solution added with ore sample 2. Alphaproteobacteria and Saccharomycetes were the dominating bacterial and fungal group, respectively, both in the solutions added with ore samples 1 and 2 at the class level. However, their abundances in the solution added with ore sample 1 were obviously lower than that in the solution added with ore sample 2. This study provides new insights into our understanding of the microbial community structure in the biosolubilization of RPs by a microbial consortium directly taken from activated sludge.

  15. Sphingosine-1-phosphate signaling and biological activities in the cardiovascular system.

    PubMed

    Takuwa, Yoh; Okamoto, Yasuo; Yoshioka, Kazuaki; Takuwa, Noriko

    2008-09-01

    The plasma lysophospholipid mediator sphingosine-1-phosphate (S1P) is produced exclusively by sphingosine kinase (SPHK) 1 and SPHK2 in vivo, and plays diverse biological and pathophysiological roles by acting largely through three members of the G protein-coupled S1P receptors, S1P1, S1P2 and S1P3. S1P1 expressed on endothelial cells mediates embryonic vascular maturation and maintains vascular integrity by contributing to eNOS activation, inhibiting vascular permeability and inducing endothelial cell chemotaxis via Gi-coupled mechanisms. By contrast, S1P2, is expressed in high levels on vascular smooth muscle cells (VSMCs) and certain types of tumor cells, inhibiting Rac and cell migration via a G(12/13)-and Rho-dependent mechanism. In rat neointimal VSMCs, S1P1 is upregulated to mediate local production of platelet-derived growth factor, which is a key player in vascular remodeling. S1P3 expressed on endothelial cells also mediates chemotaxis toward S1P and vasorelaxation via NO production in certain vascular bed, playing protective roles for vascular integrity. S1P3 expressed on VSMCs and cardiac sinoatrial node cells mediates vasopressor and negative chronotropic effect, respectively. In addition, S1P3, together with S1P2 and SPHK1, is suggested to play a protective role against acute myocardial ischemia. However, our recent work indicates that overexpressed SPHK1 is involved in cardiomyocyte degeneration and fibrosis in vivo, in part through S1P activation of the S1P3 signaling. We also demonstrated that exogenously administered S1P accelerates neovascularization and blood flow recovery in ischemic limbs, suggesting its usefulness for angiogenic therapy. These results provide evidence for S1P receptor subtype-specific pharmacological intervention as a novel therapeutic approach to cardiovascular diseases and cancer.

  16. Microbicidal activity of tripotassium phosphate and fatty acids toward spoilage and pathogenic bacteria associated with poultry.

    PubMed

    Hinton, Arthur; Ingram, Kimberly D

    2005-07-01

    The ability of solutions of tripotassium phosphate (TPP) and fatty acids (lauric and myristic acids) to reduce populations of spoilage and pathogenic microorganisms associated with processed poultry was examined. In vitro studies were conducted with cultures of bacteria (Campylobacter jejuni, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, and Staphylococcus aureus) and yeasts (Candida ernobii and Yarrowia lipolytica). Cultures of the bacteria and yeasts were suspended in solutions of TPP or mixtures of TPP with lauric or myristic acid and mixed for 5 min. Viable numbers (log CFU per milliliter) in the suspensions were enumerated on microbiological agar. Results indicated that TPP solutions are highly bactericidal toward gram-negative bacteria and that mixtures of TPP and fatty acids are highly microbicidal toward gram-negative bacteria, gram-positive bacteria, and yeasts. The microbicidal activity of mixtures of TPP and fatty acids toward the native bacterial flora of skin of processed broiler carcasses was also examined. Skin samples were washed in mixtures of TPP and fatty acid, and the populations of total aerobic bacteria, campylobacters, enterococci, E. coli, lactic acid bacteria, pseudomonads, staphylococci, and yeasts in the skin rinsates were enumerated on the appropriate microbiological media. Results indicated that washing the skin in mixtures of TPP and fatty acids produced significant reductions in the number of aerobic bacteria, campylobacters, E. coli, pseudomonads, and yeasts recovered from skin rinsates, but there was no significant reduction in the populations of enterococci, lactic acid bacteria, or staphylococci. These findings indicate that mixtures of TPP and fatty acids possess microbicidal activity against several microorganisms associated with processed poultry and that these solutions could be useful as microbicides to reduce the populations of some bacteria and yeasts associated with some poultry

  17. Lowering effect of firefly squid powder on triacylglycerol content and glucose-6-phosphate dehydrogenase activity in rat liver.

    PubMed

    Takeuchi, Hiroyuki; Morita, Ritsuko; Shirai, Yoko; Nakagawa, Yoshihisa; Terashima, Teruya; Ushikubo, Shun; Matsuo, Tatsuhiro

    2014-01-01

    Effects of dietary firefly squid on serum and liver lipid levels were investigated. Male Wistar rats were fed a diet containing 5% freeze-dried firefly squid or Japanese flying squid for 2 weeks. There was no significant difference in the liver triacylglycerol level between the control and Japanese flying squid groups, but the rats fed the firefly squid diet had a significantly lower liver triacylglycerol content than those fed the control diet. No significant difference was observed in serum triacylglycerol levels between the control and firefly squid groups. The rats fed the firefly squid had a significantly lower activity of liver glucose-6-phosphate dehydrogenase compared to the rats fed the control diet. There was no significant difference in liver fatty acid synthetase activity among the three groups. Hepatic gene expression and lipogenic enzyme activity were investigated; a DNA microarray showed that the significantly enriched gene ontology category of down-regulated genes in the firefly squid group was "lipid metabolic process". The firefly squid group had lower mRNA level of glucose-6-phosphate dehydrogenase compared to the controls. These results suggest that an intake of firefly squid decreases hepatic triacylglycerol in rats, and the reduction of mRNA level and enzyme activity of glucose-6-phosphate dehydrogenase might be related to the mechanisms.

  18. A limitation of the continuous spectrophotometric assay for the measurement of myo-inositol-1-phosphate synthase activity.

    PubMed

    Huang, Xinyi; Hernick, Marcy

    2011-10-15

    Myo-inositol-1-phosphate synthase (MIPS) catalyzes the conversion of glucose-6-phosphate to myo-inositol-1-phosphate. The reaction catalyzed by MIPS is the first step in the biosynthesis of inositol and inositol-containing molecules that serve important roles in both eukaryotes and prokaryotes. Consequently, MIPS is a target for the development of therapeutic agents for the treatment of infectious diseases and bipolar disorder. We recently reported a continuous spectrophotometric method for measuring MIPS activity using a coupled assay that allows the rapid characterization of MIPS in a multiwell plate format. Here we validate the continuous assay as a high-throughput alternative for measuring MIPS activity and report on one limitation of this assay-the inability to examine the effect of divalent metal ions (at high concentrations) on MIPS activity. In addition, we demonstrate that the activity of MIPS from Arabidopsis thaliana is moderately enhanced by the addition Mg(2+) and is not enhanced by other divalent metal ions (Zn(2+) and Mn(2+)), consistent with what has been observed for other eukaryotic MIPS enzymes. Our findings suggest that the continuous assay is better suited for characterizing eukaryotic MIPS enzymes that require monovalent cations as cofactors than for characterizing bacterial or archeal MIPS enzymes that require divalent metal ions as cofactors.

  19. Phosphate binding by cerebral microsomes in relation to adenosine-triphosphatase activity

    PubMed Central

    Rodnight, R.; Hems, D. A.; Lavin, B. E.

    1966-01-01

    1. Microsomes prepared from guinea-pig and ox brain were incubated for periods of a few seconds with low concentrations of Mg-[32P]ATP, the reaction was stopped with trichloroacetic acid and determinations were made of the phosphate bound to the acid-washed, and in some cases solvent-extracted, residue. 2. At 20 μm-ATP, at 37° and in the presence of Na+ ions, 30–50 μμmoles of phosphate/mg. of microsomal protein were bound by the preparation within 1 sec. of starting the reaction; little further change in level occurred until hydrolysis of ATP exceeded 50%, when the bound phosphate began to decline fairly rapidly to the zero-time value. 3. At 20μm-ATP without Na+ ions present or in the presence of K+ ions, the level of bound phosphate increased gradually and did not decline as ATP hydrolysis approached completion. 4. Potassium ions either inhibited the formation of Na+-dependent bound phosphate or, when added during the course of the reaction, rapidly reduced its level. 5. At 200 μm-ATP the bound phosphate formed in the presence of Na+ ions appeared to consist of a mixture of the unstable Na+-dependent type and the stable type requiring only Mg2+ ions for its formation. 6. Non-radioactive ATP added during the course of the reaction at 20 μm-ATP with Na+ions present rapidly discharged virtually all the bound 32P counts; at 200 μm-ATP only a proportion of the label was similarly discharged. The Na+-dependent bound phosphate is therefore turning over, in contrast with that formed in the absence of Na+ions, which proved more stable. 7. The Na+-dependent bound phosphate was not in the form of ATP; experiments with [14C]ATP instead of [32P]ATP showed a small and invariable binding of ATP by the preparation unaffected by Na+ ions or time of incubation. 8. Under the usual conditions employed in this work ouabain stimulated formation of Na+-dependent bound phosphate when Na+ ions were suboptimum and inhibited it when optimum Na+ ions were present. 9. The Na