Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 19.564
Filtrar
1.
Nat Commun ; 11(1): 4243, 2020 08 25.
Artículo en Inglés | MEDLINE | ID: mdl-32843625

RESUMEN

Increased extracellular Ca2+ concentrations ([Ca2+]ex) trigger activation of the NLRP3 inflammasome in monocytes through calcium-sensing receptor (CaSR). To prevent extraosseous calcification in vivo, the serum protein fetuin-A stabilizes calcium and phosphate into 70-100 nm-sized colloidal calciprotein particles (CPPs). Here we show that monocytes engulf CPPs via macropinocytosis, and this process is strictly dependent on CaSR signaling triggered by increases in [Ca2+]ex. Enhanced macropinocytosis of CPPs results in increased lysosomal activity, NLRP3 inflammasome activation, and IL-1ß release. Monocytes in the context of rheumatoid arthritis (RA) exhibit increased CPP uptake and IL-1ß release in response to CaSR signaling. CaSR expression in these monocytes and local [Ca2+] in afflicted joints are increased, probably contributing to this enhanced response. We propose that CaSR-mediated NLRP3 inflammasome activation contributes to inflammatory arthritis and systemic inflammation not only in RA, but possibly also in other inflammatory conditions. Inhibition of CaSR-mediated CPP uptake might be a therapeutic approach to treating RA.


Asunto(s)
Artritis Reumatoide/inmunología , Inflamasomas/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/metabolismo , Receptores Sensibles al Calcio/metabolismo , Animales , Calcinosis , Calcio/metabolismo , Células Cultivadas , Humanos , Inflamación , Interleucina-1beta/metabolismo , Ratones , Monocitos/metabolismo , Proteína con Dominio Pirina 3 de la Familia NLR/deficiencia , Fosfatos/metabolismo , Pinocitosis , Receptores Sensibles al Calcio/deficiencia , Transducción de Señal , Células THP-1 , alfa-2-Glicoproteína-HS/metabolismo
2.
PLoS One ; 15(7): e0235082, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32634148

RESUMEN

Kidney donation results in reductions in kidney function and lasting perturbations in phosphate homeostasis, which may lead to adverse cardiovascular sequelae. However, the acute effects of kidney donation on bone mineral parameters including regulators of calcium and phosphate metabolism are unknown. We conducted a prospective observational controlled study to determine the acute effects of kidney donation on mineral metabolism and skeletal health. Biochemical endpoints were determined before and after donation on days 1, 2 and 3, 6 weeks and 12 months in donors and at baseline, 6 weeks and 12 months in controls. Baseline characteristic of donors (n = 34) and controls (n = 34) were similar: age (53±10 vs 50±14 years, p = 0.33), BMI (26.3±2.89 vs 25.9±3.65, p = 0.59), systolic BP (128±13 vs 130±6 mmHg, p = 0.59), diastolic BP (80±9 vs 81±9 mmHg, p = 0.68) and baseline GFR (84.4±20.2 vs 83.6±25.2 ml/min/1.73m2, p = 0.89). eGFR reduced from 84.4±20.2 to 52.3±17.5 ml/min/1.73m2 (p<0.001) by day 1 with incomplete recovery by 12 months (67.7±22.6; p = 0.002). Phosphate increased by day 1 (1.1(0.9-1.2) to 1.3(1.1-1.4) mmol/L, p <0.001) but declined to 0.8(0.8-1.0) mmol/L (p<0.001) before normalizing by 6 weeks. Calcium declined on day 1 (p = 0.003) but recovered at 6 weeks or 12 months. PTH and FGF-23 remained unchanged, but α-Klotho reduced by day 1 (p = 0.001) and remained low at 6 weeks (p = 0.02) and 1 year (p = 0.04). In this study, we conclude that kidney donation results in acute disturbances in mineral metabolism characterised by a reduced phosphate and circulating α-Klotho concentration without acute changes in the phosphaturic hormones FGF23 and PTH.


Asunto(s)
Densidad Ósea , Trasplante de Riñón , Minerales/metabolismo , Donantes de Tejidos , Adulto , Estudios de Casos y Controles , Femenino , Factores de Crecimiento de Fibroblastos/metabolismo , Glucuronidasa/sangre , Humanos , Masculino , Persona de Mediana Edad , Hormona Paratiroidea/metabolismo , Fosfatos/metabolismo , Estudios Prospectivos , Factores de Tiempo
3.
Proc Natl Acad Sci U S A ; 117(25): 14322-14330, 2020 06 23.
Artículo en Inglés | MEDLINE | ID: mdl-32518115

RESUMEN

Phosphorothioate (PT) DNA modifications-in which a nonbonding phosphate oxygen is replaced with sulfur-represent a widespread, horizontally transferred epigenetic system in prokaryotes and have a highly unusual property of occupying only a small fraction of available consensus sequences in a genome. Using Salmonella enterica as a model, we asked a question of fundamental importance: How do the PT-modifying DndA-E proteins select their GPSAAC/GPSTTC targets? Here, we applied innovative analytical, sequencing, and computational tools to discover a novel behavior for DNA-binding proteins: The Dnd proteins are "parked" at the G6mATC Dam methyltransferase consensus sequence instead of the expected GAAC/GTTC motif, with removal of the 6mA permitting extensive PT modification of GATC sites. This shift in modification sites further revealed a surprising constancy in the density of PT modifications across the genome. Computational analysis showed that GAAC, GTTC, and GATC share common features of DNA shape, which suggests that PT epigenetics are regulated in a density-dependent manner partly by DNA shape-driven target selection in the genome.


Asunto(s)
Bacterias/genética , Bacterias/metabolismo , ADN Bacteriano/metabolismo , Epigénesis Genética/fisiología , Epigenómica , Fosfatos/metabolismo , 2-Aminopurina , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Secuencia de Bases , Sitios de Unión , Secuencia de Consenso , ADN Bacteriano/química , ADN Bacteriano/genética , Proteínas de Unión al ADN/metabolismo , Escherichia coli/metabolismo , Genoma Bacteriano , Salmonella enterica/genética
4.
Nanotoxicology ; 14(6): 827-846, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32552239

RESUMEN

Prior studies showed nanoparticle clearance was different in C57BL/6 versus BALB/c mice, strains prone to Th1 and Th2 immune responses, respectively. Objective: Assess nanoceria (cerium oxide, CeO2 nanoparticle) uptake time course and organ distribution, cellular and oxidative stress, and bioprocessing as a function of mouse strain. Methods: C57BL/6 and BALB/c female mice were i.p. injected with 10 mg/kg nanoceria or vehicle and terminated 0.5 to 24 h later. Organs were collected for cerium analysis; light and electron microscopy with elemental mapping; and protein carbonyl, IL-1ß, and caspase-1 determination. Results: Peripheral organ cerium significantly increased, generally more in C57BL/6 mice. Caspase-1 was significantly elevated in the liver at 6 h, to a greater extent in BALB/c mice, suggesting inflammasome pathway activation. Light microscopy revealed greater liver vacuolation in C57BL/6 mice and a nanoceria-induced decrease in BALB/c but not C57BL/6 mice vacuolation. Nanoceria increased spleen lymphoid white pulp cell density in BALB/c but not C57BL/6 mice. Electron microscopy showed intracellular nanoceria particles bioprocessed to form crystalline cerium phosphate nanoneedles. Ferritin accumulation was greatly increased proximal to the nanoceria, forming core-shell-like structures in C57BL/6 but even distribution in BALB/c mice. Conclusions: BALB/c mice were more responsive to nanoceria-induced effects, e.g. liver caspase-1 activation, reduced liver vacuolation, and increased spleen cell density. Nanoceria uptake, initiation of bioprocessing, and crystalline cerium phosphate nanoneedle formation were rapid. Ferritin greatly increased with a macrophage phenotype-dependent distribution. Further study will be needed to understand the mechanisms underlying the observed differences.


Asunto(s)
Cerio/toxicidad , Hígado/efectos de los fármacos , Nanopartículas/toxicidad , Estrés Oxidativo/efectos de los fármacos , Bazo/efectos de los fármacos , Animales , Cerio/química , Cerio/metabolismo , Femenino , Hígado/metabolismo , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Microscopía Electrónica , Nanopartículas/química , Nanopartículas/metabolismo , Fosfatos/metabolismo , Especificidad de la Especie , Bazo/metabolismo , Propiedades de Superficie , Distribución Tisular
5.
Life Sci ; 257: 117999, 2020 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-32585244

RESUMEN

AIM: This paper was mainly aimed at synthesis of Ce-containing nano-Mg-phosphate ceramic as a multifunctional material. MATERIALS AND METHODS: Two ceramics based on Mg3(PO4)2 and Ce0.2Mg2.8(PO4)2 formulas (MP and MP-C, respectively) were synthesized. The synthesized powders were characterized by XRD, TEM, Zeta potential, and FTIR. Also, their dissolution behavior was tested in Tris-HCl buffer solution. Moreover, the antimicrobial efficacy was evaluated against gram-positive bacteria (Bacillus sphaericus MTCC 511 &Staphylococcus aureus MTCC 87) and gram-negative bacteria (Enterobacter aerogenes MTCC 111 &Pseudomonas aeruginosa MTCC 1034) using dick diffusion assay and microdilution method. Furthermore, the cell viability test was performed for the ceramics on Vero cells (African green monkey kidney cells), and their antitumor activity was determined by PC3 cell line (prostatic cancer). Also, the cellular uptake was determined by the flow cytometry. KEY FINDINGS: The results showed that the substitution of Mg by Ce decreased the particle size from 40 to 90 nm for MP sample to 2-10 nm for MP-C sample and increased the degradation rate. Both samples showed excellent antimicrobial activities. Moreover, MP demonstrated more cell viability than MP-C on Vero cells at high concentrations, whereas, MP-C showed more antitumor activity on PC3 cells than MP sample. Moreover, MP-C showed a higher cell uptake than MP due to its smaller size and more negative charge. SIGNIFICANCE: Mg-phosphate ceramic can be used in this study successfully as a delivery system for cerium ions and showed a high antitumor activity, which makes it highly recommended as safe and effective cancer treatment materials.


Asunto(s)
Cerámica/farmacología , Cerio/farmacología , Compuestos de Magnesio/farmacología , Fosfatos/farmacología , Animales , Antibacterianos/farmacología , Antineoplásicos/farmacología , Bacillaceae/efectos de los fármacos , Huesos/microbiología , Huesos/cirugía , Supervivencia Celular , Cerio/metabolismo , Chlorocebus aethiops , Enterobacter aerogenes/efectos de los fármacos , Humanos , Compuestos de Magnesio/metabolismo , Pruebas de Sensibilidad Microbiana/métodos , Células PC-3 , Fosfatos/metabolismo , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Células Vero
6.
PLoS One ; 15(6): e0232633, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32555651

RESUMEN

Maize, a main crop worldwide, establishes a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi providing nutrients to the roots from soil volumes which are normally not in reach of the non-colonized root. The mycorrhizal phosphate uptake pathway (MPU) spans from extraradical hyphae to root cortex cells housing fungal arbuscules and promotes the supply of phosphate to the mycorrhizal host in exchange for photosynthetic carbon. This symbiotic association with the mycobiont has been shown to affect plant host nutritional status and growth performance. However, whether and how the MPU affects the root microbial community associated with mycorrhizal hosts in association with neighboring plants, remains to be demonstrated. Here the maize germinal Mu transposon insertion mutant pht1;6, defective in mycorrhiza-specific Pi transporter PHT1;6 gene, and wild type B73 (wt) plants were grown in mono- and mixed culture and examined under greenhouse and field conditions. Disruption of the MPU in pht1;6 resulted in strongly diminished growth performance, in reduced P allocation to photosynthetic source leaves, and in imbalances in leaf elemental composition beyond P. At the microbial community level a loss of MPU activity had a minor effect on the root-associated fungal microbiome which was almost fully restricted to AM fungi of the Glomeromycotina. Moreover, while wt grew better in presence of pht1;6, pht1;6 accumulated little biomass irrespective of whether it was grown in mono- or mixed culture and despite of an enhanced fungal colonization of its roots in co-culture with wt. This suggested that a functional MPU is prerequisite to maintain maize growth and that neighboring plants competed for AM fungal Pi in low P soil. Thus future strategies towards improving yield in maize populations on soils with low inputs of P fertilizer could be realized by enhancing MPU at the individual plant level while leaving the root-associated fungal community largely unaffected.


Asunto(s)
Micorrizas/metabolismo , Fosfatos/metabolismo , Zea mays/microbiología , Zea mays/fisiología , Biomasa , Mutación con Pérdida de Función , Hojas de la Planta/crecimiento & desarrollo , Hojas de la Planta/fisiología , Plantas Modificadas Genéticamente , Suelo/química , Simbiosis/fisiología , Zea mays/genética , Zea mays/crecimiento & desarrollo
7.
PLoS One ; 15(6): e0233896, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32492057

RESUMEN

Food insecurity is a looming threat for the burgeoning world population. Phosphorus (P), which is absorbed from soil as inorganic phosphate (Pi), is an essential macronutrient for the growth of all agricultural crops. This study reports phenotype analysis for P responses in natural field and greenhouse conditions, using 54 genotypes of foxtail millet (Setaria italica) representing wide geographic origins. The genotype responses were assessed in natural field conditions in two different seasons (monsoon and summer) under Pi-fertilized (P+) and unfertilized (P-) soil for eight above-ground traits. Enormous variations were seen among the genotypes in phenotypic responses for all the measured parameters under low P stress conditions. Variations were significant for plant height, leaf number and length, tillering ability and seed yield traits. Genotypes ISe 1234 and ISe 1541 were P+ responders, and the genotypes ISe 1181, ISe 1655, ISe 783 and ISe 1892 showed tolerance to low P for total seed yield. Genotypes that performed well under P- conditions were almost as productive as genotypes that performed well under P+ conditions suggesting some genotypes are well adapted to nutrient-poor soils. In the greenhouse, most of the genotypes produced changes in root architecture that are characteristic of P- stress, but to differing degrees. Significant variation was seen in root hair density and root hair number and in fresh and dry weight of shoot and root under P- stress. However, there was not much difference in the shoot and root total P and Pi levels of five selected high and low responding genotypes. We noticed contrasting responses in the greenhouse and natural field experiments for most of these genotypes. The leads from the study form the basis for breeding and improvement of foxtail millet for better Pi-use efficiency.


Asunto(s)
Productos Agrícolas/genética , Regulación de la Expresión Génica de las Plantas , Fosfatos/metabolismo , Fitomejoramiento , Setaria (Planta)/genética , Productos Agrícolas/metabolismo , Genoma de Planta , Genotipo , Redes y Vías Metabólicas/genética , Filogenia , Setaria (Planta)/metabolismo , Suelo/química
8.
Proc Natl Acad Sci U S A ; 117(24): 13519-13528, 2020 06 16.
Artículo en Inglés | MEDLINE | ID: mdl-32461373

RESUMEN

Networks of branched actin filaments formed by Arp2/3 complex generate and experience mechanical forces during essential cellular functions, including cell motility and endocytosis. External forces regulate the assembly and architecture of branched actin networks both in vitro and in cells. Considerably less is known about how mechanical forces influence the disassembly of actin filament networks, specifically, the dissociation of branches. We used microfluidics to apply force to branches formed from purified muscle actin and fission yeast Arp2/3 complex and observed debranching events in real time with total internal reflection fluorescence microscopy. Low forces in the range of 0 pN to 2 pN on branches accelerated their dissociation from mother filaments more than two orders of magnitude, from hours to <1 min. Neither force on the mother filament nor thermal fluctuations in mother filament shape influenced debranching. Arp2/3 complex at branch junctions adopts two distinct mechanical states with different sensitivities to force, which we name "young/strong" and "old/weak." The "young/strong" state 1 has adenosine 5'-diphosphate (ADP)-P i bound to Arp2/3 complex. Phosphate release converts Arp2/3 complex into the "old/weak" state 2 with bound ADP, which is 20 times more sensitive to force than state 1. Branches with ADP-Arp2/3 complex are more sensitive to debranching by fission yeast GMF (glia maturation factor) than branches with ADP-P i -Arp2/3 complex. These findings suggest that aging of branch junctions by phosphate release from Arp2/3 complex and mechanical forces contribute to disassembling "old" actin filament branches in cells.


Asunto(s)
Citoesqueleto de Actina/metabolismo , Complejo 2-3 Proteico Relacionado con la Actina/metabolismo , Fosfatos/metabolismo , Actinas/metabolismo , Adenosina Difosfato/metabolismo , Animales , Factor de Maduración de la Glia/metabolismo , Microfluídica , Microscopía Fluorescente , Modelos Biológicos , Unión Proteica , Conejos , Schizosaccharomyces/metabolismo , Estrés Mecánico
10.
Nat Commun ; 11(1): 2642, 2020 05 26.
Artículo en Inglés | MEDLINE | ID: mdl-32457313

RESUMEN

Bacteria acquire phosphate (Pi) by maintaining a periplasmic concentration below environmental levels. We recently described an extracellular Pi buffer which appears to counteract the gradient required for Pi diffusion. Here, we demonstrate that various treatments to outer membrane (OM) constituents do not affect the buffered Pi because bacteria accumulate Pi in the periplasm, from which it can be removed hypo-osmotically. The periplasmic Pi can be gradually imported into the cytoplasm by ATP-powered transport, however, the proton motive force (PMF) is not required to keep Pi in the periplasm. In contrast, the accumulation of Pi into the periplasm across the OM is PMF-dependent and can be enhanced by light energy. Because the conventional mechanism of Pi-specific transport cannot explain Pi accumulation in the periplasm we propose that periplasmic Pi anions pair with chemiosmotic cations of the PMF and millions of accumulated Pi pairs could influence the periplasmic osmolarity of marine bacteria.


Asunto(s)
Bacterias/metabolismo , Fosfatos/metabolismo , Alphaproteobacteria/metabolismo , Alphaproteobacteria/efectos de la radiación , Océano Atlántico , Bacterias/efectos de la radiación , Membrana Celular/metabolismo , Transporte Iónico/efectos de la radiación , Luz , Modelos Biológicos , Concentración Osmolar , Ósmosis , Periplasma/metabolismo , Fitoplancton/metabolismo , Fitoplancton/efectos de la radiación , Prochlorococcus/metabolismo , Prochlorococcus/efectos de la radiación , Fuerza Protón-Motriz , Agua de Mar/microbiología , Synechococcus/metabolismo , Synechococcus/efectos de la radiación
11.
Chemosphere ; 252: 126470, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32443258

RESUMEN

Concerns have been raised over the neurotoxicity of triphenyl phosphate (TPP), but there have been few studies of the neurotoxic effects of TPP on mammals and the underlying mechanisms. In this study, weaned male mice (C57/BL6) were used and exposed to 0, 50, or 150 mg/kg TPP daily by oral gavage for 30 days. The blood brain barrier (BBB) permeability of TPP and its metabolite diphenyl phosphate (DPP) in the brain, and TPP induced metabolomic and transcriptomic changes of the brain were investigated. The results showed that TPP and DPP can cross the BBB of mice. Histopathological examination of the brain revealed abnormalities in the hippocampus, cortex and thalamus, and mice treated with high doses showed a potential inflammation in the thalamus and hippocampus. Untargeted metabolomic results revealed that the changed level of glutamic acid, N-acetyl CoA metabolites, and organic acid in the brain of treated mice, suggest that amino acid and lipid metabolism was interfered. RNA-seq data indicated that neuronal transcription processes and cell apoptosis pathway (forkhead box (FOXO), and mitogen-activated protein kinase (MAPK) signaling pathways) were significantly affected by TPP exposure. RT-PCR showed proinflammation cytokine tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6)) levels were increased, while antioxidant genes including nuclear factor-E2-related factor 2 (Nrf2), heme oxygenase1 (HO-1) and superoxide dismutase (SOD1) decreased. These results suggest that TPP could cause a degree of neurotoxicity by inducing neuroinflammation and neuronal apoptosis, which are related to oxidative stress. The potential implications for neurophysiology and behavioral regulation cannot be ignored.


Asunto(s)
Barrera Hematoencefálica/efectos de los fármacos , Contaminantes Ambientales/toxicidad , Sistema Nervioso/efectos de los fármacos , Organofosfatos/toxicidad , Animales , Antioxidantes/metabolismo , Apoptosis , Encéfalo/efectos de los fármacos , Ácido Glutámico/metabolismo , Hipocampo/metabolismo , Inflamación/metabolismo , Masculino , Ratones , Factor 2 Relacionado con NF-E2/metabolismo , Síndromes de Neurotoxicidad , Estrés Oxidativo/efectos de los fármacos , Fosfatos/metabolismo , Superóxido Dismutasa/metabolismo , Pruebas de Toxicidad
12.
Nucleic Acids Res ; 48(9): 4811-4826, 2020 05 21.
Artículo en Inglés | MEDLINE | ID: mdl-32282918

RESUMEN

The phosphorylation pattern of Pol2 CTD Y1S2P3T4S5P6S7 repeats comprises an informational code coordinating transcription and RNA processing. cis-trans isomerization of CTD prolines expands the scope of the code in ways that are not well understood. Here we address this issue via analysis of fission yeast peptidyl-prolyl isomerase Pin1. A pin1Δ allele that does not affect growth per se is lethal in the absence of cleavage-polyadenylation factor (CPF) subunits Ppn1 and Swd22 and elicits growth defects absent CPF subunits Ctf1 and Dis2 and termination factor Rhn1. Whereas CTD S2A, T4A, and S7A mutants thrive in combination with pin1Δ, a Y1F mutant does not, nor do CTD mutants in which half the Pro3 or Pro6 residues are replaced by alanine. Phosphate-acquisition genes pho1, pho84 and tgp1 are repressed by upstream lncRNAs and are sensitive to changes in lncRNA 3' processing/termination. pin1Δ hyper-represses PHO gene expression and erases the de-repressive effect of CTD-S7A. Transcriptional profiling delineated sets of 56 and 22 protein-coding genes that are down-regulated and up-regulated in pin1Δ cells, respectively, 77% and 100% of which are downregulated/upregulated when the cis-proline-dependent Ssu72 CTD phosphatase is inactivated. Our results implicate Pin1 as a positive effector of 3' processing/termination that acts via Ssu72.


Asunto(s)
Regulación Fúngica de la Expresión Génica , Peptidilprolil Isomerasa de Interacción con NIMA/genética , Fosfoproteínas Fosfatasas/genética , Procesamiento de Término de ARN 3' , Proteínas de Schizosaccharomyces pombe/genética , Terminación de la Transcripción Genética , Factor de Especificidad de Desdoblamiento y Poliadenilación/genética , Eliminación de Gen , Peptidilprolil Isomerasa de Interacción con NIMA/química , Peptidilprolil Isomerasa de Interacción con NIMA/metabolismo , Proteínas Nucleares/genética , Fosfatos/metabolismo , Fosforilación , Dominios Proteicos/genética , Pirofosfatasas/genética , ARN Polimerasa II/genética , RNA-Seq , Regulón , Schizosaccharomyces/enzimología , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/química , Proteínas de Schizosaccharomyces pombe/metabolismo , Serina/metabolismo , Treonina/metabolismo
13.
Proc Natl Acad Sci U S A ; 117(19): 10234-10245, 2020 05 12.
Artículo en Inglés | MEDLINE | ID: mdl-32341157

RESUMEN

The nitrogen-related phosphotransferase system (PTSNtr) of Rhizobium leguminosarum bv. viciae 3841 transfers phosphate from PEP via PtsP and NPr to two output regulators, ManX and PtsN. ManX controls central carbon metabolism via the tricarboxylic acid (TCA) cycle, while PtsN controls nitrogen uptake, exopolysaccharide production, and potassium homeostasis, each of which is critical for cellular adaptation and survival. Cellular nitrogen status modulates phosphorylation when glutamine, an abundant amino acid when nitrogen is available, binds to the GAF sensory domain of PtsP, preventing PtsP phosphorylation and subsequent modification of ManX and PtsN. Under nitrogen-rich, carbon-limiting conditions, unphosphorylated ManX stimulates the TCA cycle and carbon oxidation, while unphosphorylated PtsN stimulates potassium uptake. The effects are reversed with the phosphorylation of ManX and PtsN, occurring under nitrogen-limiting, carbon-rich conditions; phosphorylated PtsN triggers uptake and nitrogen metabolism, the TCA cycle and carbon oxidation are decreased, while carbon-storage polymers such as surface polysaccharide are increased. Deleting the GAF domain from PtsP makes cells "blind" to the cellular nitrogen status. PTSNtr constitutes a switch through which carbon and nitrogen metabolism are rapidly, and reversibly, regulated by protein:protein interactions. PTSNtr is widely conserved in proteobacteria, highlighting its global importance.


Asunto(s)
Proteínas Bacterianas/metabolismo , Carbono/metabolismo , Regulación Bacteriana de la Expresión Génica , Nitrógeno/metabolismo , Fosfatos/metabolismo , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/metabolismo , Rhizobium leguminosarum/metabolismo , Proteínas Bacterianas/genética , Ciclo del Ácido Cítrico , Sistema de Fosfotransferasa de Azúcar del Fosfoenolpiruvato/genética , Fosforilación , Regiones Promotoras Genéticas , Rhizobium leguminosarum/genética , Rhizobium leguminosarum/crecimiento & desarrollo
14.
Mar Environ Res ; 158: 104954, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32217301

RESUMEN

We investigated the nutrient acquisition of the seagrass Cymodocea nodosa and the importance of sediment to water column nutrient pulses, which regularly occur in coastal lagoons forced by incoming flood tides. Ammonium was preferentially taken up and accounted for 60-90% of the total daily N acquisition, whereas amino acid acquisition through belowground plant parts represented the second most important source of N, accounting 8-34%. The uptake of ammonium pulses increased dramatically the daily N acquisition from 9.5 mmol m-2 day-1 to 1.33 mmol m-2 day-1 at ambient nutrient concentrations, enabling the species to meet its N demand. Roots accounted for 96% of the total phosphate acquisition, with no evidence for P limitation. The ability of seagrasses to adapt to nutrient pulses may be an overlooked nutrition strategy common to many ecosystems where nutrient availability in the water column is low but nutrient pulses occur.


Asunto(s)
Alismatales , Compuestos de Amonio , Fosfatos , Ecosistema , Estado Nutricional , Fosfatos/metabolismo
15.
Environ Monit Assess ; 192(4): 245, 2020 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-32198540

RESUMEN

Several strategies were undertaken to increase the fertility of landfill soil as rapid urbanization remarkably decreases the agricultural land, posing challenges to the fast-growing human population. Towards this direction, soil microcosms were prepared wherein the addition of nutrient or biofertilizer or the combination of both increased the soil nitrogen and phosphate content considerably. The maximum amount of nitrogen fixation and phosphate solubilization occurred in microcosm treated with biofertilizer and nutrient. To investigate the underlying cause, we observed that separate application of nutrient or biofertilizer or combined application of both increased the abundance of nitrogen-fixing and phosphate-solubilizing bacteria in the microcosms. However, the highest abundance of nitrogen-fixing and phosphate-solubilizing bacteria was spotted in a microcosm challenged with nutrient and biofertilizer together. It was detected that with increasing population of nitrogen-fixing and phosphate-solubilizing bacteria, the soil nitrogen and phosphate level also got enhanced, respectively, thus establishing a strong positive correlation between them. The microcosm treated with biofertilizer and nutrient manifested the highest degree of heterotrophic microbial growth and microbial activity than the microcosms either treated with nutrient or biofertilizer. The microcosm treated with nutrient and biofertilizer was found to exhibit the highest functional diversity compared to others. A surface plot was constructed to demonstrate the association among microbial activity, functional diversity, and the availability of soil nitrogen and phosphate content of soil. The result indicates that the combined application of nutrient and biofertilizer increases the microbial activity leading to the formation of a heterogeneous ecosystem that enhances the nitrogen and phosphate content of landfill soil considerably.


Asunto(s)
Nitrógeno , Fosfatos , Suelo , Residuos Sólidos , Nitrógeno/análisis , Nitrógeno/metabolismo , Fosfatos/análisis , Fosfatos/metabolismo , Suelo/química , Microbiología del Suelo , Instalaciones de Eliminación de Residuos
16.
PLoS One ; 15(3): e0230201, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32143215

RESUMEN

Medial vascular calcification (MVC) is a highly prevalent disease associated with a high risk of severe, potentially lethal, complications. While animal studies may not systematically be circumvented, in vitro systems have been proven useful to study disease physiopathology. In the context of MVC, the absence of a clinically relevant standardized in vitro method prevents the appropriate comparison and overall interpretation of results originating from different experiments. The aim of our study is to establish in vitro models mimicking in vivo vascular calcification and to select the best methods to unravel the mechanisms involved in MVC. Human aortic smooth muscle cells and rat aortic rings were cultured in different conditions. The influence of fetal calf serum (FCS), alkaline phosphatase, phosphate and calcium concentrations in the medium were evaluated. We identified culture conditions, including the herein reported Aorta Calcifying Medium (ACM), which allowed a reproducible and specific medial calcification of aortic explants. Studying cells and aortic explants cultured, the involvement of bone morphogenetic protein 2 (BMP2) pathway, fibrosis and apoptosis processes in in vitro MVC were demonstrated. Expression of osteoblastic markers was also observed suggesting the occurrence of transdifferentiation of smooth muscle cells to osteoblasts in our models. The use of these models will help researchers in the field of vascular calcification to achieve reproducible results and allow result comparison in a more consistent way.


Asunto(s)
Miocitos del Músculo Liso/patología , Calcificación Vascular/patología , Fosfatasa Alcalina/metabolismo , Animales , Aorta/metabolismo , Aorta/patología , Apoptosis/fisiología , Proteína Morfogenética Ósea 2/metabolismo , Calcio/metabolismo , Transdiferenciación Celular/fisiología , Células Cultivadas , Humanos , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patología , Miocitos del Músculo Liso/metabolismo , Osteoblastos/metabolismo , Fosfatos/metabolismo , Ratas , Ratas Wistar , Transducción de Señal/fisiología , Calcificación Vascular/metabolismo
17.
Rev Med Suisse ; 16(687): 592-595, 2020 Mar 25.
Artículo en Francés | MEDLINE | ID: mdl-32216183

RESUMEN

The occurrence of hypophosphatemia after iron infusion has been known for a long time but has only recently led to clinical concerns. It was considered to be of low clinical importance. The elucidation of the physiological mechanisms responsible for this effect, involving FGF23 and the ever-increasing number of cases with regard to the potentially very serious consequences on bone metabolism have recently raised probably justified concerns. In this article, we summarize the mechanisms of phosphate homeostasis, how intravenous iron can induce a phosphate deficiency and what precautions and treatments needs to be undertaken to prevent it.


Asunto(s)
Hipofosfatemia/inducido químicamente , Hipofosfatemia/prevención & control , Hierro/administración & dosificación , Hierro/efectos adversos , Administración Intravenosa , Humanos , Fosfatos/metabolismo
18.
Endocrinol. diabetes nutr. (Ed. impr.) ; 67(3): 205-215, mar. 2020. ilus, tab
Artículo en Español | IBECS | ID: ibc-188149

RESUMEN

La concentración sérica de fósforo oscila entre 2,5 y 4,5 mg/dl (0,81-1,45 mmol/l) en adultos, con niveles más altos en la infancia, la adolescencia y durante la gestación. El fosfato intracelular está implicado en el metabolismo intermediario y otras funciones celulares esenciales, mientras que el extracelular es fundamental para la mineralización de la matriz ósea. La fosforemia se mantiene en un estrecho rango mediante la regulación de la absorción intestinal, la redistribución y la reabsorción tubular renal de fósforo. La hipofosfatemia y la hiperfosfatemia son situaciones clínicas frecuentes, aunque, en la mayoría de las ocasiones, se trata de alteraciones leves y poco sintomáticas. Sin embargo, pueden presentarse cuadros agudos y severos que requieren tratamiento específico. En este documento elaborado por miembros del Grupo de Trabajo de Metabolismo Mineral y Óseo de la Sociedad Española de Endocrinología y Nutrición se revisan los trastornos del fosfato y se proporcionan algoritmos de manejo clínico de la hipofosfatemia y la hiperfosfatemia


Serum phosphorus levels range from 2.5 and 4.5 mg/dL (0.81-1.45 mmol/L) in adults, with higher levels in childhood, adolescence, and pregnancy. Intracellular phosphate is involved in intermediary metabolism and other essential cell functions, while extracellular phosphate is essential for bone matrix mineralization. Plasma phosphorus levels are maintained within a narrow range by regulation of intestinal absorption, redistribution, and renal tubular absorption of the mineral. Hypophosphatemia and hyperphosphatemia are common clinical situations, although changes are most often mild and oligosymptomatic. However, acute and severe conditions that require specific treatment may occur. In this document, members of the Mineral and Bone Metabolism Working Group of the Spanish Society of Endocrinology and Nutrition review phosphate disorders and provide algorithms for adequate clinical management of hypophosphatemia and hyperphosphatemia


Asunto(s)
Humanos , Fosfatos/metabolismo , Hipofosfatemia/etiología , Hipofosfatemia/fisiopatología , Hiperfosfatemia/etiología , Hiperfosfatemia/terapia , Hipofosfatemia/terapia , Fósforo Dietético , Raquitismo Hipofosfatémico/diagnóstico , Diagnóstico Diferencial
19.
Chemosphere ; 252: 126566, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32222521

RESUMEN

The effects of different concentrations of graphene oxide (GO) on intracellular metabolism in Chlorella vulgaris (C. vulgaris) and removal of nitrogen and phosphorus nutrients by C. vulgaris from synthetic wastewater were studied. The results demonstrated that cell division of Chlorella vulgaris increased at 24 h and decreased at 96 h after exposure to different concentrations of GO. The removal rates of total nitrogen (TN), ammoniacal nitrogen (NH3-N), phosphate (PO43--P), and chemical oxygen demand (COD) were 24.1%, 70.0%, 37.0%, and 39.6%, respectively, when the concentration of GO was 0.01 mg/L 10 mg/L GO induced severe plasmolysis and cytoplasmic contraction. Furthermore, the protein-like exopolysaccharide (EPS) content of algal cells exposed to 10 mg/L GO decrease to 10.8% of the control group. Simultaneously, the reactive oxygen species (ROS) level was 175.4% of control group. The biological responses to 10 mg/L GO included increase in ROS level, inhibition of saccharide metabolism, and degradation of amino acids. In addition, high concentrations of 10 mg/L GO weakened the carbon fixation process in algal cells. These stress-response behaviors increased cell permeability and oxidative stress. Overall, these findings provide new insights regarding the effects of GO on algal cellular stress responses.


Asunto(s)
Chlorella vulgaris/fisiología , Grafito/química , Ciclo del Carbono , Chlorella vulgaris/metabolismo , Nitrógeno/análisis , Nutrientes , Fosfatos/metabolismo , Fósforo/metabolismo , Eliminación de Residuos Líquidos/métodos , Aguas Residuales
20.
Ecotoxicol Environ Saf ; 194: 110411, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32151869

RESUMEN

Accidental ingestion of Pb-contaminated soil particles by direct hand-to-mouth activity or by swallowing airborne dust particles is important pathway of human exposure to Pb. Appropriate evaluation of Pb risk to human is important in determining whether the soil needs remediation or not, however, there is paucity of data about the dietary influences on Pb bioaccessibility (Pb-BA) and transformation in humans. This study chose two typical foods, spinach and cola, representing vegetable and soft drink, respectively, and investigated their effects on Pb species in gastrointestinal tract using the physiologically based extraction test. Results showed that ingestion of spinach and cola decreased the Pb-BA by 52%-94% in the gastric phase and by 38%-95% in the intestinal phase, respectively. The reduction of Pb-BA by spinach was attributed to the precipitation of Pb with phosphorus in spinach and the sorption of Pb by the generated hydrolysate and un-hydrolysate from spinach in gastrointestinal tract. Cola decreased Pb-BA mainly via formation of insoluble Pb phosphates precipitates. Analysis of X-ray diffraction and MINTEQ modeling demonstrated that the dissolved Pb was transformed to precipitated or sorbed Pb with intake of cola or spinach. Our findings suggest that dietary habit greatly influence the speciation and subsequent Pb-BA in the gastrointestinal tract, which should be incorporated into human health risk assessment of Pb-contaminated soil.


Asunto(s)
Bebidas Gaseosas/análisis , Exposición Dietética/análisis , Tracto Gastrointestinal/metabolismo , Plomo/análisis , Contaminantes del Suelo/análisis , Spinacia oleracea/química , Disponibilidad Biológica , Humanos , Fosfatos/metabolismo , Medición de Riesgo , Suelo/química , Difracción de Rayos X
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA