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Functional specialization of Eucalyptus fine roots: contrasting potential uptake rates for nitrogen, potassium and calcium tracers at varying soil depths

SILVA, Eduardo Vinicius da; BOUILLET, Jean-Pierre; GONCALVES, Jose Leonardo de Moraes; ABREU JUNIOR, Cassio Hamilton; TRIVELIN, Paulo Cesar Ocheuze; HINSINGER, Philippe; JOURDAN, Christophe; NOUVELLON, Yann; STAPE, Jose Luiz; LACLAU, Jean-Paul
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.41%
1. Little is known about the role of deep roots in the nutrition of forest trees and their ability to provide a safety-net service taking up nutrients leached from the topsoil. 2. To address this issue, we studied the potential uptake of N, K and Ca by Eucalyptus grandis trees (6 years of age - 25 m mean height), in Brazil, as a function of soil depth, texture and water content. We injected NO(3)(-)- (15)N, Rb(+) (analogue of K(+)) and Sr(2+) (analogue of Ca(2+)) tracers simultaneously in a solution through plastic tubes at 10, 50, 150 and 300 cm in depth in a sandy and a clayey Ferralsol soil. A complete randomized design was set up with three replicates of paired trees per injection depth and soil type. Recently expanded leaves were sampled at various times after tracer injection in the summer, and the experiment was repeated in the winter. Soil water contents were continuously monitored at the different depths in the two soils. 3. Determination of foliar Rb and Sr concentrations and (15)N atom % made it possible to estimate the relative uptake potential (RUP) of tracer injections from the four soil depths and the specific RUP (SRUP), defined as RUP, per unit of fine root length density in the corresponding soil layer. 4. The highest tracer uptake rates were found in the topsoil...

Modulation of dopamine uptake by nitric oxide in cultured mesencephalic neurons

SALUM, Cristiane; RAISMAN-VOZARI, Rita; MICHEL, Patrik P.; GOMES, Margarete Zanardo; MITKOVSKI, Miso; FERRARIO, Juan E.; GINESTET, Laure; BEL, Elaine A. Del
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.43%
Strong evidence obtained from in vivo and ex-vivo studies suggests the existence of interaction between dopaminergic and nitrergic systems. Some of the observations suggest a possible implication of nitric oxide (NO) in dopamine (DA) uptake mechanism. The present work investigated the interaction between both systems by examining the effect of an NO donor, sodium nitroprusside (SNP), associated with the indirect DA agonist, amphetamine (AMPH) on tritiated DA uptake in cultures of embryonic mesencephalic neurons. Consistent with the literature, both AMPH (1, 3 and 10 mu M) and SNP (300 mu M and 1 mM) inhibited DA uptake in a dose-dependent manner. In addition, the inhibition of DA uptake by AMPH (1 and 3 mu M) was significantly increased by the previous addition of SNP (300 mu M). The implication of NO in this interaction was supported by the fact that the free radical scavenger N-acetyl-L-Cysteine (500 mu M) significantly increased DA uptake and completely abolished the effect of SNP, leaving unaffected that from AMPH on DA uptake. Further, double-labeling immunohistochemistry showed the presence of tyrosine hydroxylase-(TH, marker for dopaminergic neurons) and neuronal NO synthase- (nNOS, marker for NO containing neurons) expressing neurons in mesencephalic cultures. Some dopaminergic neurons also express nNOS giving further support for a pre-synaptic interaction between both systems. This is the first work demonstrating in mesencephalic cultured neurons a combined effect of an NO donor and an indirect DA agonist on specific DA uptake. (C) 2008 Elsevier B.V. All rights reserved.

Major involvement of mTOR in the PPAR gamma-induced stimulation of adipose tissue lipid uptake and fat accretion

Blanchard, Pierre-Gilles; Festuccia, William Tadeu Lara; Houde, Vanessa P.; St-Pierre, Philippe; Brule, Sophie; Turcotte, Veronique; Cote, Marie; Bellmann, Kerstin; Marette, Andre; Deshaies, Yves
Fonte: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC; BETHESDA Publicador: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC; BETHESDA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.41%
Evidence points to a role of the mammalian target of rapamycin (mTOR) signaling pathway as a regulator of adiposity, yet its involvement as a mediator of the positive actions of peroxisome proliferator-activated receptor (PPAR)gamma agonism on lipemia, fat accretion, lipid uptake, and its major determinant lipoprotein lipase (LPL) remains to be elucidated. Herein we evaluated the plasma lipid profile, triacylglycerol (TAG) secretion rates, and adipose tissue LPL-dependent lipid uptake, LPL expression/activity, and expression profile of other lipid metabolism genes in rats treated with the PPAR gamma agonist rosiglitazone (15 mg/kg/day) in combination or not with the mTOR inhibitor rapamycin (2 mg/kg/day) for 15 days. Rosiglitazone stimulated adipose tissue mTOR complex 1 and AMPK and induced TAG-derived lipid uptake (136%), LPL mRNA/activity (2- to 6-fold), and fat accretion in subcutaneous (but not visceral) white adipose tissue (WAT; 50%) and in brown adipose tissue (BAT; 266%). Chronic mTOR inhibition attenuated the upregulation of lipid uptake, LPL expression/activity, and fat accretion induced by PPAR gamma activation in both subcutaneous WAT and BAT, which resulted in hyperlipidemia. In contrast, rapamycin did not affect most of the other WAT lipogenic genes upregulated by rosiglitazone. Together these findings demonstrate that mTOR is a major regulator of adipose tissue LPL-mediated lipid uptake and a critical mediator of the hypolipidemic and lipogenic actions of PPAR gamma activation.-Blanchard...

General aspects of muscle glucose uptake

ALVIM,RAFAEL O.; CHEUHEN,MARCEL R.; MACHADO,SILMARA R.; SOUSA,ANDRÉ GUSTAVO P.; SANTOS,PAULO C.J.L.
Fonte: Academia Brasileira de Ciências Publicador: Academia Brasileira de Ciências
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2015 EN
Relevância na Pesquisa
36.41%
Glucose uptake in peripheral tissues is dependent on the translocation of GLUT4 glucose transporters to the plasma membrane. Studies have shown the existence of two major signaling pathways that lead to the translocation of GLUT4. The first, and widely investigated, is the insulin activated signaling pathway through insulin receptor substrate-1 and phosphatidylinositol 3-kinase. The second is the insulin-independent signaling pathway, which is activated by contractions. Individuals with type 2 diabetes mellitus have reduced insulin-stimulated glucose uptake in skeletal muscle due to the phenomenon of insulin resistance. However, those individuals have normal glucose uptake during exercise. In this context, physical exercise is one of the most important interventions that stimulates glucose uptake by insulin-independent pathways, and the main molecules involved are adenosine monophosphate-activated protein kinase, nitric oxide, bradykinin, AKT, reactive oxygen species and calcium. In this review, our main aims were to highlight the different glucose uptake pathways and to report the effects of physical exercise, diet and drugs on their functioning. Lastly, with the better understanding of these pathways, it would be possible to assess...

Thyroid uptake and scintigraphy using 99mTc pertechnetate: standardization in normal individuals

Ramos,Celso Darío; Wittmann,Denise Engelbrecht Zantut; Etchebehere,Elba Cristina Sá de Camargo; Tambascia,Marcos Antonio; Silva,Cleide Aparecida Moreira; Camargo,Edwaldo Eduardo
Fonte: Associação Paulista de Medicina - APM Publicador: Associação Paulista de Medicina - APM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2002 EN
Relevância na Pesquisa
36.41%
CONTEXT: Thyroid uptake and scintigraphy using 99mTc-pertechnetate has proven to be more advantageous than with 131I-iodide, since the images have better quality, the procedure is faster and the patient is submitted to a lower radiation dose. OBJECTIVE: The purpose of this study was to standardize a simple and fast methodology for performing thyroid uptake and scintigraphy and to determine the normal values for 99mTc- pertechnetate uptake. TYPE OF STUDY: Prospective, non-randomized. SETTING: Division of Nuclear Medicine, Department of Radiology, School of Medical Sciences, Campinas State University. PARTICIPANTS: The study consisted of 47 normal individuals, 30 women and 17 men, with ages ranging from 19 to 61 years (mean of 33 years). PROCEDURES: The laboratory assessment of thyroid function consisted of serum dosages of ultra-sensitive thyroxin and thyrotrophin. Twenty minutes after an intravenous injection of 10 mCi (370 MBq) of 99mTc-pertechnetate, the images were obtained on a computerized scintillation camera equipped with a low-energy high-resolution parallel hole collimator. RESULTS: All the individuals were euthyroid both on clinical and laboratory evaluation. The baseline thyroid 99mTc-pertechnetate uptake ranged from 0.4 to 1.7%. The uptake values obtained in these normal individuals showed that 95% presented a thyroid uptake that ranged from 0.4 to 1.5% of the injected dose. CONCLUSION: The assessment of thyroid structure and function using 99mTc-pertechnetate is a simple...

Differential water uptake kinetics in axes and cotyledons during seed germination of Vigna radiata under chilling temperature and cycloheximide treatment

Chakraborty,R.; Kar,R.K.
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
Relevância na Pesquisa
36.45%
Water uptake kinetics of axes and cotyledons of Vigna radiata seeds has been studied during incubation at chilling temperature (4°C) and under cycloheximide treatment. Germination rate of scarified seeds was faster than intact seeds, which can be correlated with their comparative water uptake kinetics. Chilling temperature during incubation significantly slowed down water uptake by both intact and scarified seeds. Treatment with cycloheximide was also somewhat effective in retarding water uptake, but only in scarified seeds. Water uptake by axes isolated from intact seeds (attached or detached from the cotyledons) was inhibited completely by chilling temperature as well as by cycloheximide treatment while these treatments were ineffective in preventing water uptake by cotyledons. In the case of scarified seeds, such treatments again inhibited water uptake by axes only, the effect being more prominent in attached ones. Preincubation of intact seeds with cycloheximide for 6 h also inhibited water uptake by isolated axes, but not by cotyledons, during subsequent incubation in water.

Sodium uptake in different life stages of crustaceans: the water flea Daphnia magna Strauss

Bianchini, Adalto; Wood, Chris
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.43%
The concentration-dependent kinetics and main mechanisms of whole-body Na+ uptake were assessed in neonate and adult water flea Daphnia magna Strauss acclimated to moderately hard water (0.6mmoll–1 NaCl, 1.0•mmol•l–1 CaCO3 and 0.15•mmol•l–1 MgSO4•7H2O; pH•8.2). Whole-body Na+ uptake is independent of the presence of Cl– in the external medium and kinetic parameters are dependent on the life stage. Adults have a lower maximum capacity of Na+ transport on a mass-specific basis but a higher affinity for Na+ when compared to neonates. Based on pharmacological analyses, mechanisms involved in whole-body Na+ uptake differ according to the life stage considered. In neonates, a proton pump-coupled Na+ channel appears to play an important role in the whole-body Na+ uptake at the apical membrane. However, they do not appear to contribute to whole-body Na+ uptake in adults, where only the Na+ channel seems to be present, associated with the Na+/H+ exchanger. In both cases, carbonic anhydrase contributes by providing H+ for the transporters. At the basolateral membrane of the salt-transporting epithelia of neonates, Na+ is pumped from the cells to the extracellular fluid by a Na+,K+-ATPase and a Na+/Cl– exchanger whereas K+ and Cl– move through specific channels. In adults...

Plant uptake of 14C-EDTA, 14C-Citrate, and 14C-Histidine from chelator-buffered and conventional hydrophonic solutions

Bell, P.; McLaughlin, M.; Cozens, G.; Stevens, D.; Owens, G.; South, H.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2003 EN
Relevância na Pesquisa
36.48%
Chelator-buffered hydroponic solutions provide low and buffered free-metal concentrations and allow the easy calculation of nutrient species expected in these solutions. Some researchers suspect that the solutions allow plant uptake of chelates and that this uptake explains the failure of the free-ion activity model using these solutions. To determine the amount and method of chelate uptake, swiss chard was grown in solution culture in growth chambers for about three wks and then transferred to solutions containing 14C-EDTA, 14C-citrate, or 14C-L-histidine for a 21-hour assay. Much higher root and shoot 14C were found from treatments containing metabolites histidine (2706097 shoot Bq 14C) or citrate (2241953 shoot Bq 14C) than EDTA (280110 shoot Bq 14C). Passive transpirational flow could explain all of the EDTA uptake, but active uptake would be required to explain most of the citrate and histidine uptake even assuming some adsorption of ligand bound to roots. Swiss chard grown in solutions with the same total EDTA concentrations, but different amounts of Fe bound to EDTA, had 3-fold differences in root and shoot 14C concentrations. In a second experiment, swiss chard roots removed more EDTA from solutions containing mostly M-EDTA0 than M-EDTA1- or M-EDTA2- (288140...

Endocannabinoids and skeletal muscle glucose uptake.

Cavuoto, Paul
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
36.45%
Obesity is a risk factor for type 2 diabetes mellitus and cardiovascular disease. Obesity, in particular when the fat is predominantly visceral, is associated with insulin resistance and a reduced ability to increase the rate of fat oxidation in response to an increase in dietary fat intake. Skeletal muscle is a primary site for insulin-stimulated glucose uptake. Insulin responsiveness in skeletal muscle is regulated by a number of factors including growth hormone, cortisol, sex steroids, cytokines secreted by inflammatory cells and adipocytes, fatty acids, and fatty acid derivatives such as the endocannabinoids. The most abundant endocannabinoids, anandamide (AEA) and 2- arachidonoylglycerol (2-AG) are synthesised from arachidonic acid. They have autocrine or paracrine mechanisms of action which are rapidly terminated by cellular uptake and subsequent metabolism by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) which degrades AEA and 2-AG, respectively. AEA and 2-AG are ligands for the cannabinoid receptor type 1 (CB₁) and the cannabinoid receptor type 2 (CB₂ ); both are 7 transmembrane domain G-protein coupled receptors. AEA and 2-AG also bind to the transient receptor potential channel-vanilloid sub-family member 1 (TRPV1). TRPV1 is a putative sixtransmembrane domain protein with a pore region between segments five and six and cytoplasmic N and C termini. TRPV1 was initially discovered as a receptor for capsaicin...

The effects of legumes on arbuscular mycorrhizal colonisation and phosphorus uptake on wheat.

Hasbullah
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011
Relevância na Pesquisa
36.46%
A number of studies have shown that biomass and P uptake in cereals following legumes are higher than in cereals following cereals. The positive effect of legumes on the following wheat may be due to the growth of legumes prior to wheat and/or due to nutrients released during decomposition of legume residue that are used by the subsequent wheat. The aim of this study is to assess the effects of legumes and/or their residues on AM colonisation, P uptake and the growth of the following wheat. A series of short experiments were carried out to assess the relationship between P addition, P availability, P uptake and AM colonisation of wheat in a soil with low P availability under conditions in which N was not limiting. Young and mature faba bean shoots (FYS, FMS) and mature chickpea shoots (CP) were added to the soil at different rates. Other treatments included addition of inorganic P at different rates. As expected, inorganic P addition increased growth and P uptake, but decreased AM colonisation. AM colonisation was not correlated with available P in the soil amended with residues, whereas there was significant negative correlation between available P and AM colonisation within the treatments with inorganic P. FMS and CP addition not only decreased wheat growth and P uptake but also AM colonisation despite low P availability in the soil. It is concluded that addition of some legume residues cannot be explained solely by soil P availability. The aim of the first experiment with legume pre-crops was to identify the effect of legumes as a pre-crop and their residues on AM colonisation and P uptake by the following wheat. Four pre-crops (chickpea...

Effects of legume growth and residue decomposition on growth and phosphorus uptake in following wheat.

Mat Hassan, Hasnuri
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2012
Relevância na Pesquisa
36.43%
In phosphorus (P) deficient soils, several legumes have been shown to mobilise less labile P pools and to have a greater capacity to take up P than cereals. In conditions where N was not limiting, some legumes can increase the growth and P uptake of the following cereals which may be related to P mobilisation by the legumes. There is little information about the size of various soil P pools in the rhizosphere of legumes in soil fertilised with P although P fertiliser is often added to legumes to improve N₂ fixation. The aims of this study were to (i) compare the growth, P uptake and the concentration of rhizosphere soil P pools of different grain legumes, (ii) compare the decomposition rate of grain legume and wheat residues, and (iii) determine the effect of legume pre-crops and residue addition on growth, P uptake and concentrations of rhizosphere P pools of the following wheat. A series of plant growth experiments were carried out in a glasshouse to compare the growth of the different grain legumes and wheat and the concentrations of P pools of the rhizosphere soil. The soil pH determines the dominant P forms, therefore, two soils which were low in available P and contrasting pH (a loamy sand soil pH 8.8 and a sandy loam pH 5.4) were used in separate experiments to which soluble P was added to ensure good plant growth. Additionally...

Role of SGK1 in Salt Sensitivity of Blood Pressure and Peripheral Glucose Uptake: Studies in Knockout Mice; Role of SGK1 in Salt Sensitivity of Blood Pressure and Peripheral Glucose Uptake : Studies in Knockout Mice; Rolle von SGK1 in der Salzempfindlichkeit von Blutdruck und der Glukoseaufnahme : Studien in Knockoutmäusen

Boini, Krishna Murthy
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
EN
Relevância na Pesquisa
36.43%
Excess salt intake increases blood pressure particularly during states of hyperinsulinism and insulin resistance. Insulin is presumably effective through activation of ENaC. Excess salt intake further decreases peripheral glucose uptake thus impairing glucose tolerance. Stimulation of both, the epithelial Na+ channel ENaC and of cellular glucose uptake involves phosphatidylinositide 3-kinase (PI-3K) which signals through protein kinase B (Akt/PKB) and all three members of the serum and glucocorticoid inducible kinase (SGK) family of kinases SGK1, SGK2 and SGK3. All three kinases have been previously shown to modify a variety of transporters including ENaC and the glucose transporter SGLT1. To explore the role of SGK1 in salt sensitive hypertension and peripheral glucose uptake, experiments were performed in male or female SGK1 knockout mice (sgk1-/-) and their wild type littermates (sgk1+/+) which were subjected to standard diet, high-fat diet, high fructose diet or dexamethasone treatment and allowed free access to either tap water (control-salt) or 1% saline (high-salt). Under control diet fluid intake, blood pressure, urinary flow rate and urinary Na+, K+, Cl- excretion were similar in sgk1-/- and sgk1+/+mice, plasma aldosterone concentration was however significantly higher in sgk1-/- (1.22 ± 0.18 ng/ml) than in sgk1+/+mice (0.57 ± 0.11 ng/ml). Under standard diet...

Root morphology and phosphorus uptake by potato cultivars grown under deficient and sufficient phosphorus supply

Fernandes, Adalton M.; Soratto, Rogerio P.; Gonsales, Jaqueline R.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 190-198
ENG
Relevância na Pesquisa
36.47%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 2010/04987-6; Processo FAPESP: 2010/18600-6; Information regarding the characteristics that affect P-uptake capacity may assist in the selection of more adapted potato (Solanum tuberosum L.) cultivars and more adequate fertilization management for each cultivar. This study evaluated the P-uptake capacity of potato cultivars (Agata, Asterix, Atlantic, Markies, and Mondial) grown under P-deficient (2 mg L-1) or P-sufficient (31 mg L-1) conditions in nutrient solution and related it to physiological parameters of uptake and morphological root characteristics. When the plants were 24 days old, they were subjected to a P-uptake kinetics study. The length and surface area of roots and the uptake kinetic parameters (I-max, K-m, and C-min) varied among potato cultivars. Phosphorus-deficient potato plants had an approximately 60% smaller root surface area and an increase of 86% in the I-max and net P influx compared with the plants in P-sufficient conditions. However, these modifications in P uptake kinetics can do not influence P acquisition in the soil environment due to very limited P diffusion. The amount of P accumulated by plants grown under P-deficient conditions was directly related to the root length and surface area; a greater root surface...

Charakterisierung der Effekte verschiedener differenzierungssteigernder Substanzen auf Radioiodaufnahme, Thymidininkorporation, NIS- und Pendrin-Expression und Apoptose in der cancerogenen Schilddrüsenzelllinie FTC-238; Characterization of the effect of several differentiation-inducing substances on radioiodine uptake, thymidine corporation, NIS and Pendrin expression and apoptosis in the thyroid carcinoma cell line FTC 238

Wegenast, Sabrina
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertation; info:eu-repo/semantics/doctoralThesis
DE_DE
Relevância na Pesquisa
36.48%
Therapie der Wahl ist bei Schilddrüsenmalignomen die Thyreoidektomie. Restgewebe und Metastasen werden durch nachfolgende Radioiodtherapie ausgeschaltet. Der Nutzen der Radioiodtherapie ist dabei entscheidend von der Iodidaufnahme und damit von einem funktionsfähigen Na+/I- (NIS-) Symporter ab-hängig. In der vorgelegten Arbeit wird nach potentiellen Substanzen gesucht, die einen redifferenzierungssteigernden Effekt auf humane cancerogene Thyreozyten der Zelllinie FTC-238 ausüben. Als Parameter für eine Redifferenzierung dient die 125I-Iodidaufnahme. Parallel hierzu werden die Tranporter NIS und Pendrin immunzytochemisch, aber auch im Western Blot nachgewiesen. Die Zellproliferation wird anhand der 3H-Thymidinaufnahme beurteilt. Die Apoptose wird mit Hilfe der FACS-Analyse erfasst. Untersucht wurden nachfolgende Substanzgruppen: -Retinoide (all-trans-, 9-cis-, 13-cis-Retinsäure, all-trans- und 13-cis Retinol): Eine signifikant erhöhte 125I-Iodidaufnahme wird unter 9-cis-Retinsäure, sowie unter 13-cis-Retinsäure und unter 13-cis Retinol gemessen. Die NIS- und Pendrin- Expression der Thyreozyten ist dabei erhöht. Die 3H-Thymidinaufnahme steigt unter dem Einfluss der Retinsäuren graduell an. All-trans-Retinol induziert...

芦苇、香蒲和藨草3种挺水植物的养分吸收动力学; Kinetics of nutrient uptake by three emergent plants, phragmites australis, typha orientalis and Scirpus triqueter

Zhang, X.L.; Wang, L.X.; Liu, H.M.; Qing, H.; Liu, D.W.; Wang, W.; Liang, C.Z.; Recknagel, F.
Fonte: Science Press Publicador: Science Press
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
36.43%
采用常规耗竭法研究了浅水富营养化湖泊——乌梁素海湖滨植被带3种挺水植物芦苇、香蒲和藨草对H2PO4-、NH4+、NO3-的吸收动力学特征及差异。结果表明:3种挺水植物吸收H2PO4-时,藨草的吸收速率显著大于芦苇和香蒲,但三者对低浓度H2PO4-的适应能力均无显著差异;藨草对NH4+和NO3-的吸收速率均显著大于芦苇和香蒲,且在低浓度NO3-环境下仍能吸收该离子,但对低浓度NH4+环境的适应能力较差;与藨草相比,香蒲对NH4+的亲和力最强,吸收低浓度NH4+的效果最好。3种植物对NH4+的吸收能力均大于NO3-。挺水植物的养分吸收特征具有物种特异性并受根系结构的影响。利用植物的养分吸收特征,在富营养化湖泊生态修复中适宜用藨草治理含高浓度H2PO4-,NH4+和NO3-的水体,修复到一定程度后再种植香蒲来维持水质。; 张熙灵, 王立新, 刘华民, 清 华, 刘东伟, 王 炜, 梁存柱, Friedrich Recknagel; English Abstract: The emergent plants may differ in their capacity to assimilate nutrients from eutrophic water bodies, so the utilization of suitable emergent plants is the key part for successful restoration of shallow eutrophic lakes. This research applied the depletion method after plants were grown for 4 weeks in 1/8 Hoagland nutrient solution to study the kinetics of uptake of nutrient (H2PO4-...

Students’ uptake of physics: a study of South Australian and Filipino physics students.

Ben, Francisco
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
36.43%
The present study brought together and examined different factors that affect students' attitudes towards physics thus influencing their uptake of physics in the South Australian and Filipino contexts. The theoretical framework was designed to examine the possible relationships among student-level and school-level factors. Student-level factors include gender, attitudes towards physics, general self-esteem, motivation to learn physics, and attitudes towards computers. School-level factors include school level, school curriculum, and classroom climate which include teachers. The theoretical base was drawn from numerous research findings on how these factors affect students' attitudes towards, and thus uptake of, physics. From these findings, constructs were integrated into the theoretical framework in an attempt to answer the research questions advanced in this study. The study employed quantitative and qualitative methods. The quantitative data were collected using the Students' Uptake of Physics Study Questionnaire (SUPSQ). Several existing scales specifically designed to measure attitudes towards physics, self-esteem, motivation to learn physics, parents' aspiration for their child's education, attitudes towards computers, and classroom climate were adapted for use in the SUPSQ. Each of these scales was validated using structural equation modeling and Rasch analysis which provide inputs from a grounded psychometric perspective. In addition...

Effect of Calcium, Tannic Acid, Phytic Acid and Pectin over Iron Uptake in an In Vitro Caco-2 Cell Model

Arredondo Olguin, Miguel Armando; Briones, L.; Pizarro, F.; Jaramillo, A.; Andrews, M.
Fonte: Springer Publicador: Springer
Tipo: Artículo de revista
EN
Relevância na Pesquisa
36.46%
Artículo de publicación ISI; Calcium, phytic acid, polyphenols and fiber are major inhibitors of iron absorption and they could be found in excess in some diets, thereby altering or modifying the iron nutrition status. The purpose of this study is to evaluate the effect of calcium, tannic acid, phytic acid, and pectin over iron uptake, using an in vitro model of epithelial cells (Caco-2 cell line). Caco-2 cells were incubated with iron (10–30 μM) with or without CaCl2 (500 and 1,000 μM) for 24 h. Then, cells were challenged with phytic acid (50–150 μM); pectin (50– 150 nM) or tannic acid (100–500 μM) for another 24 h. Finally, 55Fe (10 μM) uptake was determined. Iron dialyzability was studied using an in vitro digestion method. Iron uptake in cells pre-incubated with 20 and 30 μM Fe was inhibited by CaCl2 (500 μM). Iron uptake decreased in cells cultured with tannic acid (300 μM) and CaCl2 (500– 1,000 μM) (two-way ANOVA, p=0.002). Phytic acid also decreased iron uptake mainly when cells were treated with CaCl2 (1,000 μM) (two-way ANOVA; p<0.05). Pectin slightly decreased iron uptake (p=NS). Iron dialyzability decreased when iron was mixed with CaCl2 and phytic or tannic acid (T test p<0.0001...

Valores normales de captación de 131Yodo de 2 y 24 horas; Normal (131)Iodine uptake values at 2 and 24 hours

Jaimovich F., Rodrigo; Miranda F., Karina; Jiménez R., Beatriz; Araya Quintanilla, Aída Verónica; Massardo Vega, Teresa; Carmona C., Alberto R.; Gatica R., Héctor; González E., Patricio
Fonte: SOC MEDICA SANTIAGO Publicador: SOC MEDICA SANTIAGO
Tipo: Artículo de revista
ES
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Background: Radiolabeled ioding uptake is a useful tool in the study of thyroid diseases. Aim: To obtain normal values for (131)Iodine thyroid uptake in health volunteers. Material and methods: A total of 105 subjects were included (52 males and 53 females), with a mean age of 45 years (range: 20 to 68, evenly distributed in decades). A questionnaire was applied and a clinical esamination was performed to rule out endocrine diseases. Serum TSH and anti-thyroperoxidase antibodies were also measured. The oral (131)Idose was 5-10 mu Ci, and a Thyrad equipment was used for measurements at 2 and 24 h. Results: Mean global iodine uptake was 5.5%+/-1.8% (range: 2.3-12.0) and 2 h and 16.2+/-4.8% (range: 6.5-30.1) at 24 h. The values at 2 h among women and men were 6.0+/-1.8 and 4.9+/-1.6%, respectively, (p <0.02). At 24 h, the figures were 17.3+/-4.5 and 15.0+/-4.9%, respectively (p =0.01). compared to their younger counterparts, radioactive iodine uptake was lower among volunteers older than 40 years, at 2h (5.0+/-1.7 and 6.0+/-1.8, respectively, p <0.02) and at 24 h (14.9+/-4.4 and 17.6+/-4.9%, respectively, p <0.01). Conclusions: Normal thyroid uptake values in adults are influenced by gender and age. Normal thyroid iodine uptake values are slightly higher in females. Iodine thyroid uptake values decrease slightlynin subjects aged more than 40 years.

Leaf versus root nitrogen uptake by the surfgrass Phyllospadix torreyi

Terrados, Jorge; Williams, Susan L.
Fonte: Inter Research Publicador: Inter Research
Tipo: Artículo Formato: 1027319 bytes; application/pdf
ENG
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11 pages, 6 figures.; Phyllospadix torreyi S. Watson ('surfgrass') is one of very few seagrass species that grow on rocks. Thus, unlike most other seagrasses, nutrient uptake across leaves rather than across roots might be very important for nutrient acquisition. Ammonium and nitrate+nitrite uptake by surfgrass leaves was measured under flowing water and modelled (Michaelis-Menten) as a function of external concentrations. Leaf NH4+ uptake showed a Km of 17.4 µM and a Vmax of 125.1 µmol N g dry wt(-1) h(-1). Km and Vmax values for leaf NO3- + NO2- uptake were 10.1 µM and 54.5 µmol N g dry wt(-1) h(-1), respectively. Ammonium available to the roots had little discernible effect on NH4+ uptake by leaves. Low NH4+ uptake rates by roots (<0.2 µmol N g dry wt(-1) h(-1) suggest that surfgrass acquires most of its nitrogen via its leaves.; This study was funded by the Ministerio de Educación y Ciencia, Programa de Becas de Formación de Personal Investigador en el Extranjero through a fellowship awarded to J.T.; Peer reviewed

Characterisation of CO2 and HCO3- uptake in the cyanobacterium Synechocystis sp. PCC6803

Benschop, J; Badger, Murray; Price, Graeme (Dean)
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
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The availability of a complete genome database for the cyanobacterium Synechocystis sp. PCC6803 (glucose-tolerant strain) has raised expectations that this organism would become a reference strain for work aimed at understanding the CO2-concentrating mechanism (CCM) in cyanobacteria. However, the amount of physiological data available has been relatively limited. In this report we provide data on the relative contributions of net HCO3- uptake and CO2 uptake under steady state photosynthetic conditions. Cells were compared after growth at high CO 2 (2% v/v in air) or limiting CO2 conditions (20 ppm CO2). Synechocystis has a very high dependence on net HCO 3- uptake at low to medium concentrations of inorganic carbon (Ci). At high Ci concentrations net CO2 uptake became more important but did not contribute more than 40% to the rate of photosynthetic O2 evolution. The data also confirm that high Ci cells of Synechocystis sp. PCC6803 possess a strong capacity for net HCO3- uptake under steady state photosynthetic conditions. Time course experiments show that induction of maximal Ci uptake capacity on a shift from high CO2 to low CO2 conditions was near completion by four hours. By contrast, relaxation of the induced state on return of cells to high CO2...