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1

Elevated TCA cycle function in the pathology of diet-induced hepatic insulin resistance and fatty liver[S  

PubMed Central

The manner in which insulin resistance impinges on hepatic mitochondrial function is complex. Although liver insulin resistance is associated with respiratory dysfunction, the effect on fat oxidation remains controversial, and biosynthetic pathways that traverse mitochondria are actually increased. The tricarboxylic acid (TCA) cycle is the site of terminal fat oxidation, chief source of electrons for respiration, and a metabolic progenitor of gluconeogenesis. Therefore, we tested whether insulin resistance promotes hepatic TCA cycle flux in mice progressing to insulin resistance and fatty liver on a high-fat diet (HFD) for 32 weeks using standard biomolecular and in vivo 2H/13C tracer methods. Relative mitochondrial content increased, but respiratory efficiency declined by 32 weeks of HFD. Fasting ketogenesis became unresponsive to feeding or insulin clamp, indicating blunted but constitutively active mitochondrial ?-oxidation. Impaired insulin signaling was marked by elevated in vivo gluconeogenesis and anaplerotic and oxidative TCA cycle flux. The induction of TCA cycle function corresponded to the development of mitochondrial respiratory dysfunction, hepatic oxidative stress, and inflammation. Thus, the hepatic TCA cycle appears to enable mitochondrial dysfunction during insulin resistance by increasing electron deposition into an inefficient respiratory chain prone to reactive oxygen species production and by providing mitochondria-derived substrate for elevated gluconeogenesis. PMID:22493093

Satapati, Santhosh; Sunny, Nishanth E.; Kucejova, Blanka; Fu, Xiaorong; He, Tian Teng; Méndez-Lucas, Andrés; Shelton, John M.; Perales, Jose C.; Browning, Jeffrey D.; Burgess, Shawn C.

2012-01-01

2

2-Oxoglutarate: linking TCA cycle function with amino acid, glucosinolate, flavonoid, alkaloid, and gibberellin biosynthesis  

PubMed Central

The tricarboxylic acid (TCA) cycle intermediate 2-oxoglutarate (2-OG) is used as an obligatory substrate in a range of oxidative reactions catalyzed by 2-OG-dependent dioxygenases. These enzymes are widespread in nature being involved in several important biochemical processes. We have recently demonstrated that tomato plants in which the TCA cycle enzyme 2-OG dehydrogenase (2-ODD) was antisense inhibited were characterized by early senescence and modified fruit ripening associated with differences in the levels of bioactive gibberellin (GA). Accordingly, there is now compelling evidence that the TCA cycle plays an important role in modulating the rate of flux from 2-OG to amino acid metabolism. Here we discuss recent advances in the biochemistry and molecular biology of 2-OG metabolism occurring in different biological systems indicating the importance of 2-OG and 2-OG dependent dioxygenases not only in glucosinolate, flavonoid and alkaloid metabolism but also in GA and amino acid metabolism. We additionally summarize recent findings regarding the impact of modification of 2-OG metabolism on biosynthetic pathways involving 2-ODDs. PMID:25360142

Araújo, Wagner L.; Martins, Auxiliadora O.; Fernie, Alisdair R.; Tohge, Takayuki

2014-01-01

3

Metabolism: Part II. The Tricarboxylic Acid (TCA), Citric Acid, or Krebs Cycle.  

ERIC Educational Resources Information Center

Differentiates the tricarboxylic acid (TCA) cycle (or Krebs cycle) from glycolysis, and describes the bridge between the two as being the conversion of pyruvate into acetyl coenzyme A. Discusses the eight steps in the TCA cycle, the results of isotopic labeling experiments, and the net effects of the TCA cycle. (TW)

Bodner, George M.

1986-01-01

4

11/12/13 Chapter 13 -TCA Cycle  

E-print Network

pyruvate exactly as for pyruvate decarboxylase. Next, the lipoic acid on E2 transfers the acetate from E111/12/13 1 Chapter 13 - TCA Cycle The third fate of glucose/pyruvate is complete oxidation of pyruvate to Acetyl-CoA, a form of activated acetate: G' o= ­ 33.4 kJ/mol Keq = 7x105 Remember, there are 2

O'Neil, Joe

5

Mitochondrial dysfunctions in cancer: genetic defects and oncogenic signaling impinging on TCA cycle activity.  

PubMed

The tricarboxylic acid (TCA) cycle is a central route for oxidative metabolism. Besides being responsible for the production of NADH and FADH2, which fuel the mitochondrial electron transport chain to generate ATP, the TCA cycle is also a robust source of metabolic intermediates required for anabolic reactions. This is particularly important for highly proliferating cells, like tumour cells, which require a continuous supply of precursors for the synthesis of lipids, proteins and nucleic acids. A number of mutations among the TCA cycle enzymes have been discovered and their association with some tumour types has been established. In this review we summarise the current knowledge regarding alterations of the TCA cycle in tumours, with particular attention to the three germline mutations of the enzymes succinate dehydrogenase, fumarate hydratase and isocitrate dehydrogenase, which are involved in the pathogenesis of tumours, and to the aberrant regulation of TCA cycle components that are under the control of oncogenes and tumour suppressors. PMID:24614286

Desideri, Enrico; Vegliante, Rolando; Ciriolo, Maria Rosa

2015-01-28

6

Prebiotic Metabolisms: Photo catalysis of the rTCA cycle by sphalerite colloids  

Microsoft Academic Search

Explorations of mineral catalyzed reverse tricarboxylic acid (rTCA) cycle reactions provide a window into possible mechanisms for prebiotic metabolisms and the origins of life. The excitation of nano-scale semiconducting sphalerite minerals by ultra-violate light results in reducing electrons capable of catalyzing the reduction reactions present in the rTCA cycle. Current literature has utilized ion chromatography methods to characterize catalysis of

D. M. Mangiante; B. Bowen; T. Northen; J. F. Banfield

2010-01-01

7

Glutamine oxidation maintains the TCA cycle and cell survival during impaired mitochondrial pyruvate transport.  

PubMed

Alternative modes of metabolism enable cells to resist metabolic stress. Inhibiting these compensatory pathways may produce synthetic lethality. We previously demonstrated that glucose deprivation stimulated a pathway in which acetyl-CoA was formed from glutamine downstream of glutamate dehydrogenase (GDH). Here we show that import of pyruvate into the mitochondria suppresses GDH and glutamine-dependent acetyl-CoA formation. Inhibiting the mitochondrial pyruvate carrier (MPC) activates GDH and reroutes glutamine metabolism to generate both oxaloacetate and acetyl-CoA, enabling persistent tricarboxylic acid (TCA) cycle function. Pharmacological blockade of GDH elicited largely cytostatic effects in culture, but these effects became cytotoxic when combined with MPC inhibition. Concomitant administration of MPC and GDH inhibitors significantly impaired tumor growth compared to either inhibitor used as a single agent. Together, the data define a mechanism to induce glutaminolysis and uncover a survival pathway engaged during compromised supply of pyruvate to the mitochondria. PMID:25458842

Yang, Chendong; Ko, Bookyung; Hensley, Christopher T; Jiang, Lei; Wasti, Ajla T; Kim, Jiyeon; Sudderth, Jessica; Calvaruso, Maria Antonietta; Lumata, Lloyd; Mitsche, Matthew; Rutter, Jared; Merritt, Matthew E; DeBerardinis, Ralph J

2014-11-01

8

Prebiotic Metabolisms: Photo catalysis of the rTCA cycle by sphalerite colloids  

NASA Astrophysics Data System (ADS)

Explorations of mineral catalyzed reverse tricarboxylic acid (rTCA) cycle reactions provide a window into possible mechanisms for prebiotic metabolisms and the origins of life. The excitation of nano-scale semiconducting sphalerite minerals by ultra-violate light results in reducing electrons capable of catalyzing the reduction reactions present in the rTCA cycle. Current literature has utilized ion chromatography methods to characterize catalysis of two of the five redox active rTCA cycle compounds with high yield. This technique is unable to produce the untargeted analysis required to anticipate the myriad side reactions driven by excited photoelectrons and their ensuing radicals. By employing liquid chromatography coupled to mass spectrometry (LC-MS) we can examine the complete range of metabolites present across a reaction time series. The three dimensional LC-MS data set allows for the qualitative determination of individual metabolite features, while the comparison of intensities yields quantitative rates. These results allow us to describe the complete set of reactions resultant from a single rTCA cycle organic acid on a photo-activated sphalerite surface and provide a possible mechanism for how metabolic pathways could operate in enzyme free environments.

Mangiante, D. M.; Bowen, B.; Northen, T.; Banfield, J. F.

2010-12-01

9

Fumarate hydratase (FH), an enzyme in the tricarboxylic acid (TCA) cycle,  

E-print Network

are generated) in the TCA cycle. Haem is also degraded to produce bilirubin. This linear pathway of glutamine metabolism through to bilirubin gen- eration allows for some production of mitochondrial NADH. Consistent and bilirubin excretion, including haem oxygenase 1 (Hmox1). Knockdown of Hmox1 using short hairpin RNAs reduced

Ruppin, Eytan

10

Glucose-independent glutamine metabolism via TCA cycling for proliferation and survival in B-cells  

PubMed Central

Summary Because MYC plays a causal role in many human cancers, including those with hypoxic and nutrient-poor tumor microenvironments, we have determined the metabolic responses of a MYC-inducible human Burkitt lymphoma model P493 cell line to aerobic and hypoxic conditions, and to glucose deprivation, using Stable Isotope Resolved Metabolomics. Using [U-13C]-glucose as the tracer, both glucose consumption and lactate production were increased by MYC expression and hypoxia. Using [U-13C,15N]-glutamine as the tracer, glutamine import and metabolism through the TCA cycle persisted under hypoxia, and glutamine contributed significantly to citrate carbons. Under glucose deprivation, glutamine-derived fumarate, malate, and citrate were significantly increased. Their 13C labeling patterns demonstrate an alternative energy-generating glutaminolysis pathway involving a glucose-independent TCA cycle. The essential role of glutamine metabolism in cell survival and proliferation under hypoxia and glucose deficiency, makes them susceptible to the glutaminase inhibitor BPTES, and hence could be targeted for cancer therapy. PMID:22225880

Le, Anne; Lane, Andrew N.; Hamaker, Max; Bose, Sminu; Gouw, Arvin; Barbi, Joseph; Tsukamoto, Takashi; Rojas, Camilio J.; Slusher, Barbara S.; Zhang, Haixia; Zimmerman, Lisa J.; Liebler, Daniel C.; Slebos, Robbert J.C.; Lorkiewicz, Pawel K.; Higashi, Richard M.; Fan, Teresa W. M.; Dang, Chi V.

2012-01-01

11

Down-regulation of tricarboxylic acid (TCA) cycle genes blocks progression through the first mitotic division in Caenorhabditis elegans embryos  

PubMed Central

The cell cycle is a highly regulated process that enables the accurate transmission of chromosomes to daughter cells. Here we uncover a previously unknown link between the tricarboxylic acid (TCA) cycle and cell cycle progression in the Caenorhabditis elegans early embryo. We found that down-regulation of TCA cycle components, including citrate synthase, malate dehydrogenase, and aconitase, resulted in a one-cell stage arrest before entry into mitosis: pronuclear meeting occurred normally, but nuclear envelope breakdown, centrosome separation, and chromosome condensation did not take place. Mitotic entry is controlled by the cyclin B–cyclin-dependent kinase 1 (Cdk1) complex, and the inhibitory phosphorylation of Cdk1 must be removed in order for the complex to be active. We found that following down-regulation of the TCA cycle, cyclin B levels were normal but CDK-1 remained inhibitory-phosphorylated in one-cell stage-arrested embryos, indicative of a G2-like arrest. Moreover, this was not due to an indirect effect caused by checkpoint activation by DNA damage or replication defects. These observations suggest that CDK-1 activation in the C. elegans one-cell embryo is sensitive to the metabolic state of the cell, and that down-regulation of the TCA cycle prevents the removal of CDK-1 inhibitory phosphorylation. The TCA cycle was previously shown to be necessary for the development of the early embryo in mammals, but the molecular processes affected were not known. Our study demonstrates a link between the TCA cycle and a specific cell cycle transition in the one-cell stage embryo. PMID:24550289

Rahman, Mohammad M.; Rosu, Simona; Joseph-Strauss, Daphna; Cohen-Fix, Orna

2014-01-01

12

The TCA cycle is not required for selection or survival of multidrug-resistant Salmonella  

PubMed Central

Objectives The initial aim of this study was to use a systems biology approach to analyse a ciprofloxacin-selected multidrug-resistant (MDR) Salmonella enterica serotype Typhimurium, L664. Methods The whole genome sequence and transcriptome of L664 were analysed. Site-directed mutagenesis to recreate each mutation was carried out, followed by phenotypic characterization and mutation frequency analysis. As a mutation in the TCA cycle was detected we tested the controversial hypothesis regarding the bacterial response to bactericidal antibiotics, put forward by Kohanski et al. (Cell 2007; 130: 797–810 and Mol Cell 2010; 37: 311–20), that exposure of bacteria to agents such as ciprofloxacin produces reactive oxygen species (ROS), which transiently increase the mutation rate giving rise to MDR bacteria. Results L664 contained a mutation in ramR that conferred MDR. A mutation in tctA affected the TCA cycle and conferred the inability to grow on minimal agar. The virulence of L664 was not attenuated. Ciprofloxacin exposure produced ROS in L664 and SL1344 (tctA::aph), but it was reduced and occurred later. There were no significant differences in the rates of killing or mutations per generation to antibiotic resistance between the strains. Conclusions Whilst we confirm production of ROS in response to ciprofloxacin, we have no data to support the hypothesis that this leads to selection of MDR strains. Our results indicate that the mutations in tctA and glgA were random as they did not pre-exist in the parental strain, and that the mutation in tctA did not provide a survival advantage or disadvantage in the presence of antibiotic. PMID:22186876

Ricci, Vito; Loman, Nick; Pallen, Mark; Ivens, Alasdair; Fookes, Maria; Langridge, Gemma C.; Wain, John; Piddock, Laura J. V.

2012-01-01

13

Overexpression of metabolic enzymes at the junction of glycolylsis and the TCA cycle in Escherichia coli: physiological effects and application  

E-print Network

R. ngler (Member) James C. Holste (Member) Rayford . Anthony (Head of Department) December 1999 Major Subject: Chemical Engineering ABSTRACT Overexpression of Metabolic Enzymes at the Junction of Glycolysis and the TCA Cycle in Escherichia... AND METHODS . . 1 5 2. 1 2. 2 2. 3 Strains and Plasmids Used Growth Media and Conditions Other Methods. 2. 3. 1 DNA Transductions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. 3. 2 Enzyme Assays. . 2. 3. 3 SDS-PAGE. , 2. 3. 4...

Spitzer, Richard G.

1999-01-01

14

Coordinated activation of PTA-ACS and TCA cycles strongly reduces overflow metabolism of acetate in Escherichia coli.  

PubMed

Elimination of acetate overflow in aerobic cultivation of Escherichia coli would improve many bioprocesses as acetate accumulation in the growth environment leads to numerous negative effects, e.g. loss of carbon, inhibition of growth, target product synthesis, etc. Despite many years of studies, the mechanism and regulation of acetate overflow are still not completely understood. Therefore, we studied the growth of E. coli K-12 BW25113 and several of its mutant strains affecting acetate-related pathways using the continuous culture method accelerostat (A-stat) at various specific glucose consumption rates with the aim of diminishing acetate overflow. Absolute quantitative exo-metabolome and proteome analyses coupled to metabolic flux analysis enabled us to demonstrate that onset of acetate overflow can be postponed and acetate excretion strongly reduced in E. coli by coordinated activation of phosphotransacetylase-acetyl-CoA synthetase (PTA-ACS) and tricarboxylic acid (TCA) cycles. Fourfold reduction of acetate excretion (2 vs. 8 % from total carbon) at fastest growth compared to wild type was achieved by deleting the genes responsible for inactivation of acetyl-CoA synthetase protein (pka) and TCA cycle regulator arcA. The ?pka ?arcA strain did not accumulate any other detrimental by-product besides acetate and showed identical ? max and only ~5 % lower biomass yield compared to wild type. We conclude that a fine-tuned coordination between increasing the recycling capabilities of acetate in the PTA-ACS node through a higher concentration of active acetate scavenging Acs protein and downstream metabolism throughput in the TCA cycle is necessary for diminishing overflow metabolism of acetate in E. coli and achieving higher target product production in bioprocesses. PMID:24633370

Peebo, Karl; Valgepea, Kaspar; Nahku, Ranno; Riis, Gethe; Oun, Mikk; Adamberg, Kaarel; Vilu, Raivo

2014-06-01

15

Comparison of Intact Arabidopsis thaliana Leaf Transcript Profiles during Treatment with Inhibitors of Mitochondrial Electron Transport and TCA Cycle  

PubMed Central

Plant mitochondria signal to the nucleus leading to altered transcription of nuclear genes by a process called mitochondrial retrograde regulation (MRR). MRR is implicated in metabolic homeostasis and responses to stress conditions. Mitochondrial reactive oxygen species (mtROS) are a MRR signaling component, but whether all MRR requires ROS is not established. Inhibition of the cytochrome respiratory pathway by antimycin A (AA) or the TCA cycle by monofluoroacetate (MFA), each of which initiates MRR, can increase ROS production in some plant cells. We found that for AA and MFA applied to leaves of soil-grown Arabidopsis thaliana plants, ROS production increased with AA, but not with MFA, allowing comparison of transcript profiles under different ROS conditions during MRR. Variation in transcript accumulation over time for eight nuclear encoded mitochondrial protein genes suggested operation of both common and distinct signaling pathways between the two treatments. Consequences of mitochondrial perturbations for the whole transcriptome were examined by microarray analyses. Expression of 1316 and 606 genes was altered by AA and MFA, respectively. A subset of genes was similarly affected by both treatments, including genes encoding photosynthesis-related proteins. MFA treatment resulted in more down-regulation. Functional gene category (MapMan) and cluster analyses showed that genes with expression levels affected by perturbation from AA or MFA inhibition were most similarly affected by biotic stresses such as pathogens. Overall, the data provide further evidence for the presence of mtROS-independent MRR signaling, and support the proposed involvement of MRR and mitochondrial function in plant responses to biotic stress. PMID:23028523

Yu, Jianping; Ruckle, Michael E.; McIntosh, Lee; Hock, Jeffery J.; Bingham, Scott; White, Samuel J.; George, Rajani M.; Subbaiah, Chalivendra C.; Rhoads, David M.

2012-01-01

16

tcaA Inactivation Increases Glycopeptide Resistance in Staphylococcus aureus  

PubMed Central

The experimental deletion of the tcaRAB region has been shown to increase teicoplanin resistance in Staphylococcus aureus. By sequential genetic complementation of a tcaRAB mutant, we identified tcaA as the key gene within tcaRAB that is responsible for changes in glycopeptide resistance levels. Northern blot analysis of the tcaRAB region showed that the tcaA gene is expressed only weakly over the growth cycle and is strongly inducible by teicoplanin. Among some clinical isolates tested, glycopeptide-intermediate-resistant (GISA) strains Michigan and SA137/93G were found to have truncated tcaA genes. While the former carries a nucleotide insertion that creates a premature stop codon, the latter was found to harbor an IS256 insertion. Complementation of these two GISA strains with a functional tcaA allele reduced their levels of teicoplanin and vancomycin resistance five- to eightfold and twofold, respectively. The data presented here indicate that inactivation of tcaA contributes to and plays a relevant role in glycopeptide resistance in S. aureus clinical isolates. PMID:15155184

Maki, Hideki; McCallum, Nadine; Bischoff, Markus; Wada, Akihito; Berger-Bächi, Brigitte

2004-01-01

17

Modulating effect of Withania somnifera on TCA cycle enzymes and electron transport chain in azoxymethane-induced colon cancer in mice.  

PubMed

The aim of the present investigation was to evaluate the efficacy of Withania somnifera on tricarboxylic acid (TCA) cycle enzymes and electron transport chain in azoxymethane-induced experimental colon cancer in mice. Azoxymethane at the dose of 15 mg/kg body weight was induced intraperitoneally once in a week for 28 days. The progression in colon tumor development was correlated with the appearance of the histological biomarker and aberrant crypt foci (ACF). Azoxymethane-induced colon cancer animals were treated with 400 mg/kg body weight of W. somnifera once in a week orally for 28 days. After the experimental period, the animals were killed and analyzed for TCA cycle key enzymes, such as isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH), and alpha-keto glutarate dehydrogenase (alpha-KGDH). The modulating effect of W. somnifera on TCA cycle key enzymes and electron transport chain complexes were investigated against colon cancer induced by azoxymethane in Swiss albino mice. Decreased activities of TCA cycle key enzymes such as ICDH, SDH, MDH, and alpha-KGDH in colon cancer bearing animals were observed. W. somnifera administration normalized these enzyme levels in azoxymethane-induced experimental mice. These results suggested that W. somnifera is the promising chemotherapeutic agent for the treatment of colon cancer. PMID:20136350

Muralikrishnan, Govidan; Amanullah, Safiullah; Basha, Mohamed I; Dinda, Amit K; Shakeel, Faiyaz

2010-09-01

18

Fitness of Escherichia coli during Urinary Tract Infection Requires Gluconeogenesis and the TCA Cycle  

PubMed Central

Microbial pathogenesis studies traditionally encompass dissection of virulence properties such as the bacterium's ability to elaborate toxins, adhere to and invade host cells, cause tissue damage, or otherwise disrupt normal host immune and cellular functions. In contrast, bacterial metabolism during infection has only been recently appreciated to contribute to persistence as much as their virulence properties. In this study, we used comparative proteomics to investigate the expression of uropathogenic Escherichia coli (UPEC) cytoplasmic proteins during growth in the urinary tract environment and systematic disruption of central metabolic pathways to better understand bacterial metabolism during infection. Using two-dimensional fluorescence difference in gel electrophoresis (2D-DIGE) and tandem mass spectrometry, it was found that UPEC differentially expresses 84 cytoplasmic proteins between growth in LB medium and growth in human urine (P<0.005). Proteins induced during growth in urine included those involved in the import of short peptides and enzymes required for the transport and catabolism of sialic acid, gluconate, and the pentose sugars xylose and arabinose. Proteins required for the biosynthesis of arginine and serine along with the enzyme agmatinase that is used to produce the polyamine putrescine were also up-regulated in urine. To complement these data, we constructed mutants in these genes and created mutants defective in each central metabolic pathway and tested the relative fitness of these UPEC mutants in vivo in an infection model. Import of peptides, gluconeogenesis, and the tricarboxylic acid cycle are required for E. coli fitness during urinary tract infection while glycolysis, both the non-oxidative and oxidative branches of the pentose phosphate pathway, and the Entner-Doudoroff pathway were dispensable in vivo. These findings suggest that peptides and amino acids are the primary carbon source for E. coli during infection of the urinary tract. Because anaplerosis, or using central pathways to replenish metabolic intermediates, is required for UPEC fitness in vivo, we propose that central metabolic pathways of bacteria could be considered critical components of virulence for pathogenic microbes. PMID:19478872

Alteri, Christopher J.; Smith, Sara N.; Mobley, Harry L. T.

2009-01-01

19

TCA Cycle Turnover And Serum Glucose Sources By Automated Bayesian Analysis Of NMR Spectra  

SciTech Connect

Changes in sources of serum glucose are indicative of a variety of pathological metabolic states. It is possible to measure the sources of serum glucose by the administration of deuterated water to a subject followed by analysis of the 2H enrichment levels in glucose extracted from plasma from a single blood draw by 2H NMR. Markov Chain Monte Carlo simulations of the posterior probability densities may then be used to evaluate the contribution of glycogenolysis, glycerol, and the Kreb's cycle to serum glucose. Experiments with simulated NMR spectra show that in spectra with a S/N of 20 to 1, the resulting metabolic information may be evaluated with an accuracy of about 4 percent.

Merritt, Matthew E.; Burgess, Shawn; Jeffrey, F. Mark [University of Texas Southwestern Medical Center, Mary Nell and Ralph B. Rogers Magnetic Resonance Center, Dallas, TX (United States); Sherry, A. Dean [University of Texas Southwestern Medical Center, Mary Nell and Ralph B. Rogers Magnetic Resonance Center, Dallas, TX (United States); Department of Chemistry, University of Texas at Dallas, Dallas, TX (United States); Malloy, Craig [University of Texas Southwestern Medical Center, Mary Nell and Ralph B. Rogers Magnetic Resonance Center, Dallas, TX (United States); VA North Texas Health Care System, Dallas, TX (United States); Bretthorst, G. Larry [Department of Chemistry and Radiology, Washington University, St. Louis, MO (United States)

2004-04-21

20

Fitness of Escherichia coli during Urinary Tract Infection Requires Gluconeogenesis and the TCA Cycle  

Microsoft Academic Search

Microbial pathogenesis studies traditionally encompass dissection of virulence properties such as the bacterium's ability to elaborate toxins, adhere to and invade host cells, cause tissue damage, or otherwise disrupt normal host immune and cellular functions. In contrast, bacterial metabolism during infection has only been recently appreciated to contribute to persistence as much as their virulence properties. In this study, we

Christopher J. Alteri; Sara N. Smith; Harry L. T. Mobley

2009-01-01

21

Possible Links Between Stress Defense and the Tricarboxylic Acid (TCA) Cycle in Francisella Pathogenesis*  

PubMed Central

Francisella tularensis is a highly infectious bacterium causing the zoonotic disease tularemia. In vivo, this facultative intracellular bacterium survives and replicates mainly in the cytoplasm of infected cells. We have recently identified a genetic locus, designated moxR that is important for stress resistance and intramacrophage survival of F. tularensis. In the present work, we used tandem affinity purification coupled to mass spectrometry to identify in vivo interacting partners of three proteins encoded by this locus: the MoxR-like ATPase (FTL_0200), and two proteins containing motifs predicted to be involved in protein–protein interactions, bearing von Willebrand A (FTL_0201) and tetratricopeptide (FTL_0205) motifs. The three proteins were designated here for simplification, MoxR, VWA1, and TPR1, respectively. MoxR interacted with 31 proteins, including various enzymes. VWA1 interacted with fewer proteins, but these included the E2 component of 2-oxoglutarate dehydrogenase and TPR1. The protein TPR1 interacted with one hundred proteins, including the E1 and E2 subunits of both oxoglutarate and pyruvate dehydrogenase enzyme complexes, and their common E3 subunit. Remarkably, chromosomal deletion of either moxR or tpr1 impaired pyruvate dehydrogenase and oxoglutarate dehydrogenase activities, supporting the hypothesis of a functional role for the interaction of MoxR and TPR1 with these complexes. Altogether, this work highlights possible links between stress resistance and metabolism in F. tularensis virulence. PMID:23669032

Dieppedale, Jennifer; Gesbert, Gael; Ramond, Elodie; Chhuon, Cerina; Dubail, Iharilalao; Dupuis, Marion; Guerrera, Ida Chiara; Charbit, Alain

2013-01-01

22

Possible links between stress defense and the tricarboxylic acid (TCA) cycle in Francisella pathogenesis.  

PubMed

Francisella tularensis is a highly infectious bacterium causing the zoonotic disease tularemia. In vivo, this facultative intracellular bacterium survives and replicates mainly in the cytoplasm of infected cells. We have recently identified a genetic locus, designated moxR that is important for stress resistance and intramacrophage survival of F. tularensis. In the present work, we used tandem affinity purification coupled to mass spectrometry to identify in vivo interacting partners of three proteins encoded by this locus: the MoxR-like ATPase (FTL_0200), and two proteins containing motifs predicted to be involved in protein-protein interactions, bearing von Willebrand A (FTL_0201) and tetratricopeptide (FTL_0205) motifs. The three proteins were designated here for simplification, MoxR, VWA1, and TPR1, respectively. MoxR interacted with 31 proteins, including various enzymes. VWA1 interacted with fewer proteins, but these included the E2 component of 2-oxoglutarate dehydrogenase and TPR1. The protein TPR1 interacted with one hundred proteins, including the E1 and E2 subunits of both oxoglutarate and pyruvate dehydrogenase enzyme complexes, and their common E3 subunit. Remarkably, chromosomal deletion of either moxR or tpr1 impaired pyruvate dehydrogenase and oxoglutarate dehydrogenase activities, supporting the hypothesis of a functional role for the interaction of MoxR and TPR1 with these complexes. Altogether, this work highlights possible links between stress resistance and metabolism in F. tularensis virulence. PMID:23669032

Dieppedale, Jennifer; Gesbert, Gael; Ramond, Elodie; Chhuon, Cerina; Dubail, Iharilalao; Dupuis, Marion; Guerrera, Ida Chiara; Charbit, Alain

2013-08-01

23

The Effect of Walterinnesia aegyptia Venom Proteins on TCA Cycle Activity and Mitochondrial NAD+-Redox State in Cultured Human Fibroblasts  

PubMed Central

Fibroblast cultures were used to study the effects of crude Walterinnesia aegyptia venom and its F1–F7 protein fractions on TCA cycle enzyme activities and mitochondrial NAD-redox state. Confluent cells were incubated with 10??g of venom proteins for 4 hours at 37°C. The activities of all studied TCA enzymes and the non-TCA mitochondrial NADP+-dependent isocitrate dehydrogenase underwent significant reductions of similar magnitude (50–60% of control activity) upon incubation of cells with the crude venom and fractions F4, F5, and F7 and 60–70% for fractions F3 and F6. In addition, the crude and fractions F3–F7 venom proteins caused a drop in mitochondrial NAD+ and NADP+ levels equivalent to around 25% of control values. Whereas the crude and fractions F4, F5, and F7 venom proteins caused similar magnitude drops in NADH and NADPH (around 55% of control levels), fractions F3 and F6 caused a more drastic drop (60–70% of control levels) of both reduced coenzymes. Results indicate that the effects of venom proteins could be directed at the mitochondrial level and/or the rates of NAD+ and NADP+ biosynthesis. PMID:25705684

Ghneim, Hazem K.; Al-Sheikh, Yazeed A.; Aboul-Soud, Mourad A. M.

2015-01-01

24

Contribution of the tricarboxylic acid (TCA) cycle and the glyoxylate shunt in Saccharomyces cerevisiae to succinic acid production during dough fermentation.  

PubMed

Succinic acid produced by yeast during bread dough fermentation can significantly affect the rheological properties of the dough. By introducing mutations in the model S288C yeast strain, we show that the oxidative pathway of the TCA cycle and the glyoxylate shunt contribute significantly to succinic acid production during dough fermentation. More specifically, deletion of ACO1 and double deletion of ACO1 and ICL1 resulted in a 36 and 77% decrease in succinic acid levels in fermented dough, respectively. Similarly, double deletion of IDH1 and IDP1 decreased succinic acid production by 85%, while also affecting the fermentation rate. By contrast, double deletion of SDH1 and SDH2 resulted in a two-fold higher succinic acid accumulation compared to the wild-type. Deletion of fumarate reductase activity (FRD1 and OSM1) in the reductive pathway of the TCA cycle did not affect the fermentation rate and succinic acid production. The changes in the levels of succinic acid produced by mutants ?idh1?idp1 (low level) and ?sdh1?sdh2 (high level) in fermented dough only resulted in small pH differences, reflecting the buffering capacity of dough at a pH of around 5.1. Moreover, Rheofermentometer analysis using these mutants revealed no difference in maximum dough height and gas retention capacity with the dough prepared with S288C. The impact of the changed succinic acid profile on the organoleptic or antimicrobial properties of bread remains to be demonstrated. PMID:25828707

Rezaei, Mohammad N; Aslankoohi, Elham; Verstrepen, Kevin J; Courtin, Christophe M

2015-07-01

25

TCA Cycle-Mediated Generation of ROS Is a Key Mediator for HeR-MRSA Survival under ?-Lactam Antibiotic Exposure  

PubMed Central

Methicillin-resistant Staphylococcus aureus (MRSA) is a major multidrug resistant pathogen responsible for several difficult-to-treat infections in humans. Clinical Hetero-resistant (HeR) MRSA strains, mostly associated with persistent infections, are composed of mixed cell populations that contain organisms with low levels of resistance (hetero-resistant HeR) and those that display high levels of drug resistance (homo-resistant HoR). However, the full understanding of ?-lactam-mediated HeR/HoR selection remains to be completed. In previous studies we demonstrated that acquisition of the HoR phenotype during exposure to ?-lactam antibiotics depended on two key elements: (1) activation of the SOS response, a conserved regulatory network in bacteria that is induced in response to DNA damage, resulting in increased mutation rates, and (2) adaptive metabolic changes redirecting HeR-MRSA metabolism to the tricarboxylic acid (TCA) cycle in order to increase the energy supply for cell-wall synthesis. In the present work, we identified that both main mechanistic components are associated through TCA cycle-mediated reactive oxygen species (ROS) production, which temporally affects DNA integrity and triggers activation of the SOS response resulting in enhanced mutagenesis. The present work brings new insights into a role of ROS generation on the development of resistance to ?-lactam antibiotics in a model of natural occurrence, emphasizing the cytoprotective role in HeR-MRSA survival mechanism. PMID:24932751

Rosato, Roberto R.; Fernandez, Regina; Paz, Liliana I.; Singh, Christopher R.; Rosato, Adriana E.

2014-01-01

26

Functional Studies of ssDNA Binding Ability of MarR Family Protein TcaR from Staphylococcus epidermidis  

PubMed Central

The negative transcription regulator of the ica locus, TcaR, regulates proteins involved in the biosynthesis of poly-N-acetylglucosamine (PNAG). Absence of TcaR increases PNAG production and promotes biofilm formation in Staphylococci. Previously, the 3D structure of TcaR in its apo form and its complex structure with several antibiotics have been analyzed. However, the detailed mechanism of multiple antibiotic resistance regulator (MarR) family proteins such as TcaR is unclear and only restricted on the binding ability of double-strand DNA (dsDNA). Here we show by electrophoretic mobility shift assay (EMSA), electron microscopy (EM), circular dichroism (CD), and Biacore analysis that TcaR can interact strongly with single-stranded DNA (ssDNA), thereby identifying a new role in MarR family proteins. Moreover, we show that TcaR preferentially binds 33-mer ssDNA over double-stranded DNA and inhibits viral ssDNA replication. In contrast, such ssDNA binding properties were not observed for other MarR family protein and TetR family protein, suggesting that the results from our studies are not an artifact due to simple charge interactions between TcaR and ssDNA. Overall, these results suggest a novel role for TcaR in regulation of DNA replication. We anticipate that the results of this work will extend our understanding of MarR family protein and broaden the development of new therapeutic strategies for Staphylococci. PMID:23029170

Chang, Yu-Ming; Chen, Cammy K. -M.; Chang, Yuan-Chih; Jeng, Wen-Yih; Hou, Ming-Hon; Wang, Andrew H. -J.

2012-01-01

27

NCORRECTEDPROOF TCA 73951 18  

E-print Network

; Vaporization enthalpy; Correlation-gas chromatography18 19 1. Introduction20 Correlation-gas chromatography (GC the use of correlation-gas chromatography is28 such an instance to evaluate the vaporization enthalpyNCORRECTEDPROOF TCA 73951 1­8 Thermochimica Acta xxx (2005) xxx­xxx Application of correlation-gas

Chickos, James S.

28

Combined effects of CO2 enrichment and elevated growth temperatures on metabolites in soybean leaflets: evidence for dynamic changes of TCA cycle intermediates.  

PubMed

Soybean (Glycine max [Merr.] L.) was grown in indoor chambers with ambient (38 Pa) and elevated (70 Pa) CO2 and day/night temperature treatments of 28/20, 32/24 and 36/28 °C. We hypothesized that CO2 enrichment would mitigate the deleterious effects of elevated growth temperatures on metabolites in soybean leaflets. Net CO2 assimilation rates increased incrementally with growth temperature and were enhanced up to 24 % on average by CO2 enrichment. Stomatal conductance about doubled from the lowest to highest temperature but this was partially reversed by CO2 enrichment. Metabolites were measured thrice daily and 19 and 28 of 43 total leaf metabolites were altered by the 32/24 and 36/28 °C temperature treatments, respectively, in both CO2 treatments. Polyols, raffinose and GABA increased and 23 nonstructural carbohydrates, organic acids and amino acids decreased when the temperature was increased from 28 to 36 °C under ambient CO2. Citrate, aconitate and 2-oxoglutarate decreased over 90 % in the 36/28 °C compared to the 28/20 °C temperature treatment. Temperature-dependent changes of sugars, organic acids and all but three amino acids were almost completely eliminated by CO2 enrichment. The above findings suggested that specific TCA cycle intermediates were highly depleted by heat stress under ambient CO2. Mitigating effects of CO2 enrichment on soybean leaflet metabolites were attributed to altered rates of photosynthesis, photorespiration, dark respiration, the anaplerotic pathway and to possible changes of gene expression. PMID:23716183

Sicher, Richard

2013-08-01

29

The Cc Chemokine Thymus-Derived Chemotactic Agent 4 (Tca-4, Secondary Lymphoid Tissue Chemokine, 6ckine, Exodus-2) Triggers Lymphocyte Function–Associated Antigen 1–Mediated Arrest of Rolling T Lymphocytes in Peripheral Lymph Node High Endothelial Venules  

PubMed Central

T cell homing to peripheral lymph nodes (PLNs) is defined by a multistep sequence of interactions between lymphocytes and endothelial cells in high endothelial venules (HEVs). After initial tethering and rolling via L-selectin, firm adhesion of T cells requires rapid upregulation of lymphocyte function–associated antigen 1 (LFA-1) adhesiveness by a previously unknown pathway that activates a G?i-linked receptor. Here, we used intravital microscopy of murine PLNs to study the role of thymus-derived chemotactic agent (TCA)-4 (secondary lymphoid tissue chemokine, 6Ckine, Exodus-2) in homing of adoptively transferred T cells from T-GFP mice, a transgenic strain that expresses green fluorescent protein (GFP) selectively in naive T lymphocytes (TGFP cells). TCA-4 was constitutively presented on the luminal surface of HEVs, where it was required for LFA-1 activation on rolling TGFP cells. Desensitization of the TCA-4 receptor, CC chemokine receptor 7 (CCR7), blocked TGFP cell adherence in wild-type HEVs, whereas desensitization to stromal cell–derived factor (SDF)-1? (the ligand for CXC chemokine receptor 4 [CXCR4]) did not affect TGFP cell behavior. TCA-4 protein was not detected on the luminal surface of PLN HEVs in plt/plt mice, which have a congenital defect in T cell homing to PLNs. Accordingly, TGFP cells rolled but did not arrest in plt/plt HEVs. When TCA-4 was injected intracutaneously into plt/plt mice, the chemokine entered afferent lymph vessels and accumulated in draining PLNs. 2 h after intracutaneous injection, luminal presentation of TCA-4 was detectable in a subset of HEVs, and LFA-1–mediated TGFP cell adhesion was restored in these vessels. We conclude that TCA-4 is both required and sufficient for LFA-1 activation on rolling T cells in PLN HEVs. This study also highlights a hitherto undocumented role for chemokines contained in afferent lymph, which may modulate leukocyte recruitment in draining PLNs. PMID:10620605

Stein, Jens V.; Rot, Antal; Luo, Yi; Narasimhaswamy, Manjunath; Nakano, Hideki; Gunn, Michael D.; Matsuzawa, Akio; Quackenbush, Elizabeth J.; Dorf, Martin E.; von Andrian, Ulrich H.

2000-01-01

30

ATCA/?TCA for physics  

NASA Astrophysics Data System (ADS)

ATCA/?TCA platforms are attractive because of the modern serial link architecture, high availability features and many packaging options. Less-demanding availability applications can be met economically by scaling back speed and redundancy. The ATCA specification was originally targeted for the Telecom industry but has gained recently a much wider user audience. The purpose of this paper is to report on present hardware and software R&D efforts where ATCA and ?TCA are planned, already being used or in development using selected examples for accelerator and detectors in the Physics community. It will present also the status of a proposal for physics extensions to ATCA/?TCA specifications to promote inter-operability of laboratory and industry designs for physics.

Jezynski, Tomasz; Larsen, Raymond; Le Du, Patrick

2010-11-01

31

Evolution and Functional Implications of the Tricarboxylic Acid Cycle as Revealed by Phylogenetic Analysis  

PubMed Central

The tricarboxylic acid (TCA) cycle, a crucial component of respiratory metabolism, is composed of a set of eight enzymes present in the mitochondrial matrix. However, most of the TCA cycle enzymes are encoded in the nucleus in higher eukaryotes. In addition, evidence has accumulated demonstrating that nuclear genes were acquired from the mitochondrial genome during the course of evolution. For this reason, we here analyzed the evolutionary history of all TCA cycle enzymes in attempt to better understand the origin of these nuclear-encoded proteins. Our results indicate that prior to endosymbiotic events the TCA cycle seemed to operate only as isolated steps in both the host (eubacterial cell) and mitochondria (alphaproteobacteria). The origin of isoforms present in different cell compartments might be associated either with gene-transfer events which did not result in proper targeting of the protein to mitochondrion or with duplication events. Further in silico analyses allow us to suggest new insights into the possible roles of TCA cycle enzymes in different tissues. Finally, we performed coexpression analysis using mitochondrial TCA cycle genes revealing close connections among these genes most likely related to the higher efficiency of oxidative phosphorylation in this specialized organelle. Moreover, these analyses allowed us to identify further candidate genes which might be used for metabolic engineering purposes given the importance of the TCA cycle during development and/or stress situations. PMID:25274566

Cavalcanti, João Henrique Frota; Esteves-Ferreira, Alberto A.; Quinhones, Carla G.S.; Pereira-Lima, Italo A.; Nunes-Nesi, Adriano; Fernie, Alisdair R.; Araújo, Wagner L.

2014-01-01

32

MicroTCA and AdvancedTCA equipment evaluation and customization for LHC experiments  

NASA Astrophysics Data System (ADS)

The MicroTCA and AdvancedTCA industry standards are candidate modular electronics platforms for the upgrade of the current generation of high energy physics experiments at CERN. The PH-ESE group at CERN launched an xTCA evaluation project with the aim of performing technical evaluations and providing support for commercially available components. Over the past years, different equipment from different vendors has been acquired and evaluated. This paper summarizes our evaluation results of commercial MicroTCA and AdvancedTCA equipment. Special emphasis is put on the component requirements to be defined in view of future equipment procurement. Customized prototypes developed according to these generic specifications are presented for the first time.

Di Cosmo, M.; Bobillier, V.; Haas, S.; Joos, M.; Mico, S.; Vasey, F.

2015-01-01

33

Development of a MicroTCA Carrier Hub for CMS at HL-LHC  

NASA Astrophysics Data System (ADS)

We are developing a Micro TCA Carrier Hub card which provides timing, control and data acquisition functions in a Micro TCA crate for HL-LHC readout electronics. This module may be mounted in the primary or redundant MCH slot in a Micro TCA crate, and distributes low-jitter LHC RF clock and encoded fast timing signals to up to 12 AMC modules. In addition, it receives buffer status signals and DAQ data at up to 600 MBytes/sec from each AMC. The prototype module is built on a commercial MCH base board with a custom mezzanine board stack. The latest Xilinx® Virtex®-6 FPGA are used to provide a clear upgrade path. Prototype modules have been developed for a CMS HCAL test beam in summer 2010. We describe the specifications of the module, its application in a Micro TCA system beyond CMS HCAL, and our experience in commissioning the module for the test beam.

Dimitriyev, M.; Hazen, E.; Wu, S. X.; Rohlf, J.

2010-12-01

34

The Tribolium castaneum cell line TcA: a new tool kit for cell biology  

PubMed Central

The red flour beetle, Tribolium castaneum, is an agriculturally important insect pest that has been widely used as a model organism. Recently, an adherent cell line (BCIRL-TcA-CLG1 or TcA) was developed from late pupae of the red flour beetle. Next generation transcriptome sequencing of TcA cells demonstrated expression of a wide variety of genes associated with specialized functions in chitin metabolism, immune responses and cellular and systemic RNAi pathways. Accordingly, we evaluated the sensitivity of TcA cells to dsRNA to initiate an RNAi response. TcA cells were highly sensitive to minute amounts of dsRNA, with a minimum effective dose of 100?pg/mL resulting in significant suppression of gene expression. We have also developed a plasmid containing two TcA-specific promoters, the promoter from the 40S ribosomal protein subunit (TC006550) and a bi-directional heat shock promoter (TcHS70) from the intergenic space between heat shock proteins 68a and b. These promoters have been employed to provide high levels of either constitutive (TC006550) or inducible (TcHS70) gene expression of the reporter proteins. Our results show that the TcA cell line, with its sensitivity to RNAi and functional TcA-specific promoters, is an invaluable resource for studying basic molecular and physiological questions. PMID:25354547

Silver, Kristopher; Jiang, Hongbo; Fu, Jinping; Phillips, Thomas W.; Beeman, Richard W.; Park, Yoonseong

2014-01-01

35

The Tribolium castaneum cell line TcA: a new tool kit for cell biology.  

PubMed

The red flour beetle, Tribolium castaneum, is an agriculturally important insect pest that has been widely used as a model organism. Recently, an adherent cell line (BCIRL-TcA-CLG1 or TcA) was developed from late pupae of the red flour beetle. Next generation transcriptome sequencing of TcA cells demonstrated expression of a wide variety of genes associated with specialized functions in chitin metabolism, immune responses and cellular and systemic RNAi pathways. Accordingly, we evaluated the sensitivity of TcA cells to dsRNA to initiate an RNAi response. TcA cells were highly sensitive to minute amounts of dsRNA, with a minimum effective dose of 100 pg/mL resulting in significant suppression of gene expression. We have also developed a plasmid containing two TcA-specific promoters, the promoter from the 40S ribosomal protein subunit (TC006550) and a bi-directional heat shock promoter (TcHS70) from the intergenic space between heat shock proteins 68a and b. These promoters have been employed to provide high levels of either constitutive (TC006550) or inducible (TcHS70) gene expression of the reporter proteins. Our results show that the TcA cell line, with its sensitivity to RNAi and functional TcA-specific promoters, is an invaluable resource for studying basic molecular and physiological questions. PMID:25354547

Silver, Kristopher; Jiang, Hongbo; Fu, Jinping; Phillips, Thomas W; Beeman, Richard W; Park, Yoonseong

2014-01-01

36

Cardiovascular functioning during the menstrual cycle.  

PubMed

Variations in cardiovascular functioning during the 'normal' menstrual cycle have been little researched. Resting-blood pressures, resting-heart rate, rate-pressure product (RPP) and a derived index of fitness (Schneider Index) were monitored throughout natural, hormonally defined menstrual cycles. Volunteers were 26 women (20-48 years) who had regular (25-35 days) cycles. Their blood pressures and heart rate (at rest and according to Schneider's protocol) were measured at the same time daily (Monday-Friday) for 5 weeks. Daily, early morning-urine samples were assayed for sex hormones enabling accurate definition of cycle phase for each woman. Resting systolic-blood pressure was significantly higher in the ovulatory phase (P < 0.05) than in the follicular or luteal phases, but resting-diastolic pressures did not differ significantly between phases. Resting-heart rate was significantly higher in both ovulatory (P < 0.01) and luteal (P < 0.01) phases than in the menstrual and follicular phases. The Schneider Index was higher during the follicular phase than during the ovulatory (P < 0.005) or luteal (P < 0.01) phases, the RPP was higher during the ovulatory phase than during the bleeding (P < 0.05) and follicular (P < 0.005) phases. These findings provide a pattern of menstrual cycle-related variation in cardiovascular functioning that can be related to established actions of the ovarian steroids. PMID:11100398

Moran, V H; Leathard, H L; Coley, J

2000-11-01

37

In folio respiratory fluxomics revealed by 13C isotopic labeling and H/D isotope effects highlight the noncyclic nature of the tricarboxylic acid "cycle" in illuminated leaves.  

PubMed

While the possible importance of the tricarboxylic acid (TCA) cycle reactions for leaf photosynthesis operation has been recognized, many uncertainties remain on whether TCA cycle biochemistry is similar in the light compared with the dark. It is widely accepted that leaf day respiration and the metabolic commitment to TCA decarboxylation are down-regulated in illuminated leaves. However, the metabolic basis (i.e. the limiting steps involved in such a down-regulation) is not well known. Here, we investigated the in vivo metabolic fluxes of individual reactions of the TCA cycle by developing two isotopic methods, (13)C tracing and fluxomics and the use of H/D isotope effects, with Xanthium strumarium leaves. We provide evidence that the TCA "cycle" does not work in the forward direction like a proper cycle but, rather, operates in both the reverse and forward directions to produce fumarate and glutamate, respectively. Such a functional division of the cycle plausibly reflects the compromise between two contrasted forces: (1) the feedback inhibition by NADH and ATP on TCA enzymes in the light, and (2) the need to provide pH-buffering organic acids and carbon skeletons for nitrate absorption and assimilation. PMID:19675152

Tcherkez, Guillaume; Mahé, Aline; Gauthier, Paul; Mauve, Caroline; Gout, Elizabeth; Bligny, Richard; Cornic, Gabriel; Hodges, Michael

2009-10-01

38

Chemopreventive effect of piperine on mitochondrial TCA cycle and phase-I and glutathione-metabolizing enzymes in benzo(a)pyrene induced lung carcinogenesis in Swiss albino mice  

Microsoft Academic Search

Piperine is a major component of black (Piper nigrum Linn) and long pepper (Piper longum Linn) used widely in various systems of traditional medicine. We have evaluated the effect of piperine on mitochondrial tricarboxylic acid cycle and phase I and glutathione-metabolizing enzymes in Benzo(a)pyrene induced experimental lung carcinogenesis in swiss albino mice. Lung cancer bearing mice showed a significant decrease

K. Selvendiran; C. Thirunavukkarasu; J. Prince Vijeya Singh; R. Padmavathi; D. Sakthisekaran

2005-01-01

39

Cell Cycle Phase Regulates Glucocorticoid Receptor Function  

PubMed Central

The glucocorticoid receptor (GR) is a member of the nuclear hormone receptor superfamily of ligand-activated transcription factors. In contrast to many other nuclear receptors, GR is thought to be exclusively cytoplasmic in quiescent cells, and only translocate to the nucleus on ligand binding. We now demonstrate significant nuclear GR in the absence of ligand, which requires nuclear localisation signal 1 (NLS1). Live cell imaging reveals dramatic GR import into the nucleus through interphase and rapid exclusion of the GR from the nucleus at the onset of mitosis, which persists into early G1. This suggests that the heterogeneity in GR distribution is reflective of cell cycle phase. The impact of cell cycle–driven GR trafficking on a panel of glucocorticoid actions was profiled. In G2/M-enriched cells there was marked prolongation of glucocorticoid-induced ERK activation. This was accompanied by DNA template-specific, ligand-independent GR transactivation. Using chimeric and domain-deleted receptors we demonstrate that this transactivation effect is mediated by the AF1 transactivation domain. AF-1 harbours multiple phosphorylation sites, which are consensus sequences for kinases including CDKs, whose activity changes during the cell cycle. In G2/M there was clear ligand independent induction of GR phosphorylation on residues 203 and 211, both of which are phosphorylated after ligand activation. Ligand-independent transactivation required induction of phospho-S211GR but not S203GR, thereby directly linking cell cycle driven GR modification with altered GR function. Cell cycle phase therefore regulates GR localisation and post-translational modification which selectively impacts GR activity. This suggests that cell cycle phase is an important determinant in the cellular response to Gc, and that mitotic index contributes to tissue Gc sensitivity. PMID:21829454

Matthews, Laura; Johnson, James; Berry, Andrew; Trebble, Peter; Cookson, Ann; Spiller, Dave; Rivers, Caroline; Norman, Michael; White, Mike; Ray, David

2011-01-01

40

Reese/Doering 4/2004 TCA PRECIPITATION  

E-print Network

Reese/Doering 4/2004 TCA PRECIPITATION OVERVIEW This is a standard method for precipitating protein-PAGE). It may also be used to precipitate a very dilute or low abundance sample, in which case a carrier protein

Doering, Tamara

41

Preliminary Evaluation of Nonlinear Effects on TCA Flutter  

NASA Technical Reports Server (NTRS)

The objective of this study is to investigate the effect of nonlinear aerodynamics, especially at high angles-of-attack with leading-edge separation, on the TCA flutter properties at transonic speeds. In order to achieve that objective, flutter simulations with Navier-Stokes CFD must be performed. To this end, time-marching Navier-Stokes solutions are computed for the TCA wing/body configuration at high angles-of-attack in transonic flight regimes. The approach is to perform non-linear flutter calculations on the TCA at two angles-of-attack, the first one being a case with attached flow (a=2.8 degrees) and the second one being a high angle-of-attack case with a wing leading edge vortex (a=12.11 degrees). Comparisons of the resulting histories and frequency damping information for both angles-of-attack will evaluate the impact of high-alpha aerodynamics on flutter.

Arslan, Alan E.; Hartwich, Peter M.; Baker, Myles L.

1998-01-01

42

Cell function defined by cycles Mechanosensation  

E-print Network

cycle of mechanotransduction #12;CSK and ECM proteins have tandem-repeated sequences 3 Force induces such as how cells sense mechanical signals and transduce them into a cascade of biochemical signals ultimately

Sniadecki, Nathan J.

43

Functional properties of the isomorphic biphasic algal life cycle  

Microsoft Academic Search

Synopsis Many species of marine algae have life cycles that involve multiple separate, free-living phases that frequently differ in ploidy levels. These complex life cycles have received increasing scientific attention over the past few decades, due to their usefulness for both ecological and evolutionary studies. I present a synthesis of our current knowledge of the ecological functioning and evolutionary implications

Carol S. Thornber

2006-01-01

44

Thioredoxin, a master regulator of the tricarboxylic acid cycle in plant mitochondria.  

PubMed

Plant mitochondria have a fully operational tricarboxylic acid (TCA) cycle that plays a central role in generating ATP and providing carbon skeletons for a range of biosynthetic processes in both heterotrophic and photosynthetic tissues. The cycle enzyme-encoding genes have been well characterized in terms of transcriptional and effector-mediated regulation and have also been subjected to reverse genetic analysis. However, despite this wealth of attention, a central question remains unanswered: "What regulates flux through this pathway in vivo?" Previous proteomic experiments with Arabidopsis discussed below have revealed that a number of mitochondrial enzymes, including members of the TCA cycle and affiliated pathways, harbor thioredoxin (TRX)-binding sites and are potentially redox-regulated. We have followed up on this possibility and found TRX to be a redox-sensitive mediator of TCA cycle flux. In this investigation, we first characterized, at the enzyme and metabolite levels, mutants of the mitochondrial TRX pathway in Arabidopsis: the NADP-TRX reductase a and b double mutant (ntra ntrb) and the mitochondrially located thioredoxin o1 (trxo1) mutant. These studies were followed by a comparative evaluation of the redistribution of isotopes when (13)C-glucose, (13)C-malate, or (13)C-pyruvate was provided as a substrate to leaves of mutant or WT plants. In a complementary approach, we evaluated the in vitro activities of a range of TCA cycle and associated enzymes under varying redox states. The combined dataset suggests that TRX may deactivate both mitochondrial succinate dehydrogenase and fumarase and activate the cytosolic ATP-citrate lyase in vivo, acting as a direct regulator of carbon flow through the TCA cycle and providing a mechanism for the coordination of cellular function. PMID:25646482

Daloso, Danilo M; Müller, Karolin; Obata, Toshihiro; Florian, Alexandra; Tohge, Takayuki; Bottcher, Alexandra; Riondet, Christophe; Bariat, Laetitia; Carrari, Fernando; Nunes-Nesi, Adriano; Buchanan, Bob B; Reichheld, Jean-Philippe; Araújo, Wagner L; Fernie, Alisdair R

2015-03-17

45

The damage function approach for estimating fuel cycle externalities  

SciTech Connect

This paper discusses the methodology used in a study of fuel cycle externalities sponsored by the US Department of Energy and the Commission of the European Communities. The methodology is the damage function approach. This paper describes that approach and discusses its application and limitations. The fuel cycles addressed are those in which coal, biomass, oil, hydro, natural gas and uranium are used to generate electric power. The methodology is used to estimate the physical impacts of these fuel cycles on environmental resources and human health, and the external costs and benefits of these impacts.

Lee, R.

1993-10-01

46

Intellectual Performance as a Function of Repression and Menstrual Cycle.  

ERIC Educational Resources Information Center

Performance on complex (Space Relations and Verbal Reasoning) and simple (Digit Symbol) tests was investigated as a function of Byrne's Repression-Sensitization (RS) dimension, phase of menstrual cycle and premenstrual-menstrual (PM) symptomatology in a group of females not taking oral contraceptives. Two control groups, consisting of males and…

Englander-Golden, Paula; And Others

47

Extremes, rainflow cycles and damage functionals in continuous random processes  

Microsoft Academic Search

We discuss some properties of damage functionals defined on a sequence of local extremes in continuous stochastic processes both irregular, e.g. Brownian motion, diffusions, and smooth, e.g. stationary Gaussian processes with finite intensity of local maxima. Local extremes are represented as a point process in R2. The main tools are rainflow cycles and oscillation measures.

Igor Rychlik

1996-01-01

48

Threshold functions for asymmetric Ramsey properties involving cycles  

E-print Network

Threshold functions for asymmetric Ramsey properties involving cycles Y. Kohayakawa Instituto de to find sharp thresholds for various Ramsey properties that a random graph may satisfy. Let us concentrate. Here we shall consider the asymmetric case, namely, when we have one target graph for each colour

Kohayakawa, Yoshiharu

49

Does prolonged cycling of moderate intensity affect immune cell function?  

PubMed Central

Background: Prolonged exercise may induce temporary immunosuppression with a presumed increased susceptibility for infection. However, there are only few data on immune cell function after prolonged cycling at moderate intensities typical for road cycling training sessions. Methods: The present study examined the influence on immune cell function of 4 h of cycling at a constant intensity of 70% of the individual anaerobic threshold. Interleukin-6 (IL-6) and C-reactive protein (CRP), leukocyte and lymphocyte populations, activities of natural killer (NK), neutrophils, and monocytes were examined before and after exercise, and also on a control day without exercise. Results: Cycling for 4 h induced a moderate acute phase response with increases in IL-6 from 1.0 (SD 0.5) before to 9.6 (5.6) pg/ml 1 h after exercise and CRP from 0.5 (SD 0.4) before to 1.8 (1.3) mg/l 1 day after exercise. Although absolute numbers of circulating NK cells, monocytes, and neutrophils increased during exercise, on a per cell basis NK cell activity, neutrophil and monocyte phagocytosis, and monocyte oxidative burst did not significantly change after exercise. However, a minor effect over time for neutrophil oxidative burst was noted, tending to decrease after exercise. Conclusions: Prolonged cycling at moderate intensities does not seem to seriously alter the function of cells of the first line of defence. Therefore, the influence of a single typical road cycling training session on the immune system is only moderate and appears to be safe from an immunological point of view. PMID:15728699

Scharhag, J; Meyer, T; Gabriel, H; Schlick, B; Faude, O; Kindermann, W; Shephard, R

2005-01-01

50

Destruction of 1,1,1-trichloroethane (TCA) using Non-Thermal Plasma (NTP)  

E-print Network

Destruction of 1,1,1-trichloroethane (TCA) using Non- Thermal Plasma (NTP) Paper # (42930) Sandeep to determine the feasibility of using non-thermal plasma (NTP) for destruction of 1,1,1-trichloroethane (TCA stationary sources must be monitored and controlled. Non-Thermal Plasma Non-thermal plasma (NTP) is a new

Cal, Mark P.

51

Induction of PDGF-B in TCA-treated epidermal keratinocytes.  

PubMed

Trichloroacetic acid (TCA) is one of the most widely used peeling agents, and induces full necrosis of the whole epidermis, followed by reconstitution of the epidermis and the matrix of the papillary dermis. The cytotoxic effects of TCA, such as suppressing proliferation of keratinocytes and fibroblasts and protein synthesis by fibroblasts, have already been reported. However, the entire biological mechanism responsible for TCA peeling has yet to be determined. Hypothetical activation effects of TCA treatment on epidermal cells to induce production of growth factors and cytokines are examined, and are compared with its cytotoxic effects in terms of time course and applied TCA concentrations. After various periods of incubation with TCA, viability of Pam212 murine keratinocytes was investigated with MTT assay and dye exclusion assay, and production of growth factors and cytokines with reverse transcription-polymerase chain reaction (RT-PCR). Changes in platelet-derived growth factor (PDGF)-B mRNA expression and protein production in the human skin specimens after TCA application were then examined by RT-PCR and immunohistochemistry, respectively. Incubation with TCA showed cytotoxicity and induced death of Pam212 cells, depending on the incubation period and the TCA concentration. In addition, expressions of PDGF-B, tumor growth factor (TGF)-alpha, TGF- beta1 and vascular endothelial growth factor, which are the growth factors reportedly secreted from keratinocytes during wound healing, were all detected in Pam212 cells after short-term treatment with TCA. Expressions of inflammatory cytokines such as interleukin (IL)-1 and IL-10 were also induced. In TCA-treated NIH-3T3 fibroblasts, in contrast, observed was upregulation of only keratinocyte growth factor, which is reportedly secreted from fibroblasts, as well as the similar cytotoxic effect. In human skin, PDGF-B mRNA expression became significantly upregulated after TCA application, and then immediately downregulated. Immunoreactive PDGF-B in the cytoplasm of keratinocytes became detectable throughout the epidermis after TCA application, reached maximum after the peak of mRNA expression, and then declined significantly over 24 h when the epidermis became completely necrotic. The TCA-treated epidermis acts as a major source of growth factors, including PDGF-B, before undergoing full necrosis. This effect might contribute to a promotion of re-epithelialization and dermal regeneration without wound contraction and scarring. PMID:17724602

Yonei, Nozomi; Kanazawa, Nobuo; Ohtani, Toshio; Furukawa, Fukumi; Yamamoto, Yuki

2007-11-01

52

Preliminary Results of the 1.5% TCA (Modular) Controls Model in the NASA Langley UPWT  

NASA Technical Reports Server (NTRS)

To summarize the significant highlights in this report: (1) Data quality, determined by multiple repeat runs performed on the TCA baseline configuration, and long-term repeatability, determined by comparing baseline Reference H data from this test to a previous test, have been shown to be good. (2) The longitudinal stability of the TCA is more non-linear than for the Reference H, and while it is similar at normal lift values, the TCA has considerably more pitch-up at higher lift. (3) Longitudinal control effectiveness of the TCA is similar to the Reference H and the ratio of elevator effectiveness to horizontal tail effectiveness is approximately 0.3. (4) The directional stability of the TCA is improved relative to Reference H at higher angles-of attack. The chine is effective for improving directional stability.

Kubiatko, Paul; McMillin, Naomi; Cameron, Douglas C.

1999-01-01

53

Urea cycle defects and hyperammonemia: effects on functional imaging.  

PubMed

The urea-cycle disorders (UCDs) are a group of congenital enzyme and carrier deficiencies predisposing to hyperammonemia (HA). HA causes changes in the central nervous system (CNS) including alterations of neurotransmitter function, cell volume, and energy deprivation ultimately leading to cerebral edema. Neuropathological findings of UCDs primarily reflect changes in astrocyte morphology. Neurological features accompanying acute HA include changes in behavior and consciousness in the short term, and potential for impairments in memory and executive function as long-term effects. Plasma measures of ammonia and glutamine, although useful for clinical monitoring, prove poor markers of CNS function. Multimodal neuroimaging has potential to investigate impact on cognitive function by interrogating neural networks, connectivity and biochemistry. As neuroimaging methods become increasingly sophisticated, they will play a critical role in clinical monitoring and treatment of metabolic disease. We describe our findings in UCDs; with focus on Ornithine Transcarbamylase deficiency (OTCD) the only X linked UCD. PMID:23149878

Gropman, Andrea L; Prust, Morgan; Breeden, Andrew; Fricke, Stanley; VanMeter, John

2013-06-01

54

TcaR, a Putative MarR-Like Regulator of sarS Expression  

PubMed Central

TcaR, which shares sequence homology with MarR-like transcriptional regulators, has been identified as a novel Staphylococcus aureus regulator affecting the expression of the global regulatory element SarS (SarH1), as well as that of the cell surface-associated protein SasF (N315-SA2439). Microarray analysis, confirmatory Northern blots, and genetic complementation experiments showed that TcaR upregulates sarS and thus spa transcription. In addition, it attenuates whole-length transcription of sasF, thereby producing a truncated transcript lacking the 3? terminus, which codes for the cell wall anchor motif. Hence, in strains containing an intact tcaR gene, TcaR is likely to decrease the amount of the surface-associated protein SasF and to increase that of the surface-associated protein A. The widely used laboratory strains derived from NCTC8325 were found to be natural, truncated mutants of tcaR, harboring an inactive TcaR and therefore expressing very low levels of sarS. The data presented here identified TcaR as a further activator of sarS, and a modulator of sasF expression that has to be taken into account in studies of virulence gene expression in S. aureus. PMID:15126456

McCallum, Nadine; Bischoff, Markus; Maki, Hideki; Wada, Akihito; Berger-Bächi, Brigitte

2004-01-01

55

ANALYSIS AND SIMULATION OF RECYCLE SO2-LIME SLURRY IN TCA (TURBULENT CONTACT ABSORBER) SCRUBBER SYSTEM  

EPA Science Inventory

The report gives results of an analysis of flue gas desulfurization by a turbulent contact absorber (TCA) employing lime slurry, including the development of performance equations for the scrubber-hold tank recycle system. Performance characteristics investigated include pressure...

56

Quantum chemical study, spectroscopic investigations, NBO and HOMO-LUMO analyses of 3-aminoquinoline (3AQ) and [Ag(3AQ)2(TCA)] complex (TCA = Trichloroacetate)  

NASA Astrophysics Data System (ADS)

The new [Ag(3AQ)2(TCA)]; (3AQ = 3-aminoquinoline and TCA = Trichloroacetate) complex is synthesized and characterized using elemental analysis, FTIR, NMR and mass spectroscopy. The molecular geometry, vibrational frequencies, gauge-including atomic orbital (GIAO) 1H chemical shift values of the free and coordinated 3AQ in the ground state have been calculated by using DFT/B3LYP method. The TD-DFT results of the [Ag(3AQ)2(TCA)] complex showed a ?-?* transition band at 240.3-242.6 nm (f = 0.1334-0.1348) which has longer wavelength and lower absorption intensity than that for the free 3AQ (233.2 nm, f = 0.3958). Dipole moment, polarizability and HOMO-LUMO gap values predicted better nonlinear optical properties (NLO) for the [Ag(3AQ)2(TCA)] than the 3AQ ligand. NBO analysis has been used to predict the most accurate Lewis structure of the studied molecules. The energies of the different intramolecular charge transfer (ICT) interactions within the studied molecules were estimated using second order perturbation theory.

Soliman, Saied M.; Kassem, Taher S.; Badr, Ahmed M. A.; Abu Youssef, Morsy A.; Assem, Rania

2014-09-01

57

High-Level Functional and Operational Requirements for the Advanced Fuel Cycle Facilty  

SciTech Connect

High-Level Functional & Operational Requirements for the AFCF -This document describes the principal functional and operational requirements for the proposed Advanced Fuel Cycle Facility (AFCF). The AFCF is intended to be the world's foremost facility for nuclear fuel cycle research, technology development, and demonstration. The facility will also support the near-term mission to develop and demonstrate technology in support of fuel cycle needs identified by industry, and the long-term mission to retain and retain U.S. leadership in fuel cycle operations. The AFCF is essential to demonstrate a more proliferation-resistant fuel cycle and make long-term improvements in fuel cycle effectiveness, performance and economy.

Charles Park

2006-12-01

58

TcaR–ssDNA complex crystal structure reveals new DNA binding mechanism of the MarR family proteins  

PubMed Central

The teicoplanin-associated locus regulator (TcaR) regulates gene expression of proteins on the intercellular adhesion (ica) locus involved in staphylococci poly-N-acetylglucosamine biosynthesis. The absence of TcaR increases poly-N-acetylglucosamine production and promotes biofilm formation. Until recently, the mechanism of multiple antibiotic resistance regulator family protein members, such as TcaR, was restricted to binding double-stranded DNA. However, we recently found that TcaR strongly interacts with single-stranded DNA, which is a new role for this family of proteins. In this study, we report Staphylococcus epidermidis TcaR–single-stranded DNA complex structures. Our model suggests that TcaR and single-stranded DNA form a 61-symmetry polymer composed of TcaR dimers with single-stranded DNA that wraps outside the polymer and 12 nt per TcaR dimer. Single-stranded DNA binding to TcaR involves a large conformational change at the DNA binding lobe. Several point mutations involving the single-stranded DNA binding surface validate interactions between single-stranded DNA and TcaR. Our results extend the novel role of multiple antibiotic resistance regulator family proteins in staphylococci. PMID:24531929

Chang, Yu-Ming; Ho, Chun-Han; Chen, Cammy K.-M.; Maestre-Reyna, Manuel; Chang-Chien, Masatoshi Weiting; Wang, Andrew H.-J.

2014-01-01

59

The annual course of TCA formation in the lower troposphere: a modeling study.  

PubMed

We present a modeling study investigating the influence of climate conditions and solar radiation intensity on gas-phase trichloroacetic acid (TCA) formation. As part of the ECCA-project (Ecotoxicological Risk in the Caspian Catchment Area), this modeling study uses climate data specific for the two individual climate regimes, namely "Kalmykia" and "Kola Peninsula". A third regime has also been included in this study, namely "Central Europe", which serves as a reference to somehow more moderate climate conditions. The simulations have been performed with a box modeling package (SBOX, photoRACM), which uses Regional Atmospheric Chemistry Mechanism (RACM) as its chemistry scheme. For this model a mechanism supplement has been developed including the reaction pathways of methyl chloroform photooxidation. The investigations are completed by a detailed sensitivity study addressing the impact of temperature and relative humidity. Atmospheric OH and HO2 concentrations and the NOx/HO2 ratio were identified as the governing quantities controlling the TCA formation trough methyl chloroform oxidation in the gas phase. Model calculations show a TCA production rate ranging between almost zero and 6.5 x 10(3) molecules cm(-3) day(-1) depending on location and season. In the Kalmykia regime the model predicts mean TCA production rates of 1.3 x 10(-4) and 5.4 x 10(-5) microg m(-3) year(-1) for the urban and rural environment, respectively. From the comparison of model calculations with measured TCA burdens in the soil ranging between 130 g m(-3) and 1750 g m(-3) we conclude that TCA formation through methyl chloroform photooxidation in the gas-phase is probably not the principal atmospheric TCA source in this region. PMID:12758020

Folberth, Gerd; Pfister, Gabriele; Baumgartner, Dietmar; Putz, Erich; Weissflog, Ludwig; Elansky, Nikolai P

2003-01-01

60

Functions of microtubules in the Saccharomyces cerevisiae cell cycle  

PubMed Central

We used the inhibitor nocodazole in conjunction with immunofluorescence and electron microscopy to investigate microtubule function in the yeast cell cycle. Under appropriate conditions, this drug produced a rapid and essentially complete disassembly of cytoplasmic and intranuclear microtubules, accompanied by a rapid and essentially complete block of cellular and nuclear division. These effects were similar to, but more profound than, the effects of the related drug methyl benzimidazole carbamate (MBC). In the nocodazole-treated cells, the selection of nonrandom budding sites, the formation of chitin rings and rings of 10-nm filaments at those sites, bud emergence, differential bud enlargement, and apical bud growth appeared to proceed normally, and the intracellular distribution of actin was not detectably perturbed. Thus, the cytoplasmic microtubules are apparently not essential for the establishment of cell polarity and the localization of cell-surface growth. In contrast, nocodazole profoundly affected the behavior of the nucleus. Although spindle-pole bodies (SPBs) could duplicate in the absence of microtubules, SPB separation was blocked. Moreover, complete spindles present at the beginning of drug treatment appeared to collapse, drawing the opposed SPBs and associated nuclear envelope close together. Nuclei did not migrate to the mother-bud necks in nocodazole-treated cells, although nuclei that had reached the necks before drug treatment remained there. Moreover, the double SPBs in arrested cells were often not oriented toward the budding sites, in contrast to the situation in normal cells. Thus, microtubules (cytoplasmic, intranuclear, or both) appear to be necessary for the migration and proper orientation of the nucleus, as well as for SPB separation, spindle function, and nuclear division. PMID:3049620

1988-01-01

61

Over-expression of Gadd45a enhances radiotherapy efficacy in human Tca8113 cell line  

PubMed Central

Aim: To investigate the effect of the growth arrest- and DNA damage-inducible Gadd45a gene on the radiosensitivity of human tongue squamous cell carcinoma cell line to ionizing radiation (IR). Methods: Short interfering ribonucleic acid (si-RNA) targeting Gadd45a or an irrelevant mRNA (nonsense si-RNA) was chemically synthesized. The constructed si-RNAs were transfected into Tca8113 cells and Gadd45a expression was determined using quantitative real-time PCR and Western-blot. After 24-h exposure to IR at a dose rate of 4 Gy/min, apoptosis of Tca8113 cells was detected using flow cytometry, and radiosensitivity was measured using MTT assays. Results: IR apparently increased the expression of Gadd45a at mRNA and protein levels in Tca8113 cells. The effect was efficiently inhibited by transfection with Gadd45a si-RNA (P<0.01). Furthermore, silencing Gadd45a gene significantly increased cell viability and decreased the percentage of apoptotic cells during irradiation, which indicated that IR-induced Gadd45a over-expression could increase the radiosensitivity of Tca8113 cells. Conclusion: These results indicated that targeting Gadd45a may have important therapeutic implications in sensitizing Tca8113 cells to IR. PMID:21293478

Zhang, Xiao-ying; Qu, Xun; Wang, Cheng-qin; Zhou, Cheng-jun; Liu, Gui-xiang; Wei, Feng-cai; Sun, Shan-zhen

2011-01-01

62

NMR indirect detection of glutamate to measure citric acid cycle flux in the isolated perfused mouse heart.  

PubMed

(13)C-edited proton nuclear magnetic resonance (NMR) spectroscopy was used to follow enrichment of glutamate C3 and C4 with a temporal resolution of approximately 20 s in mouse hearts perfused with (13)C-enriched substrates. A fit of the NMR data to a kinetic model of the tricarboxylic acid (TCA) cycle and related exchange reactions yielded TCA cycle (V(tca)) and exchange (V(x)) fluxes between alpha-ketoglutarate and glutamate. These fluxes were substrate-dependent and decreased in the order acetate (V(tca)=14.1 micromol g(-1) min(-1); V(x)=26.5 micromol g(-1) min(-1))>octanoate (V(tca)=6.0 micromol g(-1) min(-1); V(x)=16.1 micromol g(-1) min(-1))>lactate (V(tca)=4.2 micromol g(-1) min(-1); V(x)=6.3 micromol g(-1) min(-1)). PMID:11557062

Burgess, S C; Babcock, E E; Jeffrey, F M; Sherry, A D; Malloy, C R

2001-09-01

63

Cell-cycle-dependent regulation of androgen receptor function.  

PubMed

The androgen receptor (AR) is a critical oncogene in prostate cancer (PCa) development and progression. In this study, we demonstrate cell-cycle-dependent regulation of AR activity, localization, and phosphorylation. We show that for three AR-target genes, androgen-stimulated AR transactivation is highest during the G1 phase, decreased during S-phase, and abrogated during G2/M. This change in AR transactivation parallels changes in AR localization and phosphorylation. A combination of imaging techniques and quantitative analysis reveals nuclear AR localization during interphase and the exclusion of the majority, but not all, AR from chromatin during mitosis. Flow cytometry analyses using a phospho-S308 AR-specific antibody in asynchronous and chemically enriched G2/M PCa cells revealed ligand-independent induction of S308 phosphorylation in mitosis when CDK1 is activated. Consistent with our flow cytometry data, IP-western blotting revealed an increase in S308 phosphorylation in G2/M, and the results of an in vitro kinase assay indicated that CDK1 was able to phosphorylate the AR on S308. Pharmacological inhibition of CDK1 activity resulted in decreased S308 phosphorylation in PCa cells. Importantly, using a combination of anti-total AR and phospho-S308-specific antibodies in immunofluorescence experiments, we showed that the AR is excluded from condensed chromatin in mitotic cells when it was phosphorylated on S308. In summary, we show that the phosphorylation of the AR on S308 by CDK1 during mitosis regulates AR localization and correlates with changes in AR transcriptional activity. These findings have important implications for understanding the function of AR as an oncogene. PMID:25691442

Koryakina, Yulia; Knudsen, Karen E; Gioeli, Daniel

2015-04-01

64

IPbus: a flexible Ethernet-based control system for xTCA hardware  

NASA Astrophysics Data System (ADS)

The ATCA and ?TCA standards include industry-standard data pathway technologies such as Gigabit Ethernet which can be used for control communication, but no specific hardware control protocol is defined. The IPbus suite of software and firmware implements a reliable high-performance control link for particle physics electronics, and has successfully replaced VME control in several large projects. In this paper, we outline the IPbus control system architecture, and describe recent developments in the reliability, scalability and performance of IPbus systems, carried out in preparation for deployment of ?TCA-based CMS upgrades before the LHC 2015 run. We also discuss plans for future development of the IPbus suite.

Ghabrous Larrea, C.; Harder, K.; Newbold, D.; Sankey, D.; Rose, A.; Thea, A.; Williams, T.

2015-02-01

65

Chapter 4 Regulation and Functions of the Chlorophyll Cycle  

Microsoft Academic Search

\\u000a The chlorophyll cycle refers to the interconversion of chlorophyll a and chlorophyll b that occurs within the chloroplasts of higher plants. The forward reaction that converts chlorophyll a to b is catalyzed by chlorophyllide a oxygenase. The backward reaction from chlorophyll b to a is catalyzed by a recently identified enzyme, chlorophyll b reductase, and an unidentified enzyme, which is

Ryouichi Tanaka; Hisashi Ito; Ayumi Tanaka

66

THE FUNCTION OF THE CITRIC ACID CYCLE IN SACCHAROMYCES CEREVISIAE  

Microsoft Academic Search

The role of the citric acid cycle in yeast was investigated. ; Suspensions of fasting Saccharomyces cerevisiae were incubated with carbon-14 ; bicarbonate and substrates in a closed vessel connected with a volume ; compensator, and simultaneous measurements of the oxygen consumption were made ; under equal experimental conditions. (C.H.);

A. O. M. Stoppani; S. L. S. de Favelukes; L. Conches; E. Ramos; M. M. Pigretti

1959-01-01

67

Uncertainty of Prebiotic Scenarios: The Case of the Non-Enzymatic Reverse Tricarboxylic Acid Cycle  

NASA Astrophysics Data System (ADS)

We consider the hypothesis of the primordial nature of the non-enzymatic reverse tricarboxylic acid (rTCA) cycle and describe a modeling approach to quantify the uncertainty of this hypothesis due to the combinatorial aspect of the constituent chemical transformations. Our results suggest that a) rTCA cycle belongs to a degenerate optimum of auto-catalytic cycles, and b) the set of targets for investigations of the origin of the common metabolic core should be significantly extended.

Zubarev, Dmitry Yu; Rappoport, Dmitrij; Aspuru-Guzik, Alán

2015-01-01

68

Uncertainty of Prebiotic Scenarios: The Case of the Non-Enzymatic Reverse Tricarboxylic Acid Cycle  

PubMed Central

We consider the hypothesis of the primordial nature of the non-enzymatic reverse tricarboxylic acid (rTCA) cycle and describe a modeling approach to quantify the uncertainty of this hypothesis due to the combinatorial aspect of the constituent chemical transformations. Our results suggest that a) rTCA cycle belongs to a degenerate optimum of auto-catalytic cycles, and b) the set of targets for investigations of the origin of the common metabolic core should be significantly extended. PMID:25620471

Zubarev, Dmitry Yu; Rappoport, Dmitrij; Aspuru-Guzik, Alán

2015-01-01

69

Influence of menstrual cycle phase on pulmonary function in asthmatic athletes  

Microsoft Academic Search

The main aim of this study was to investigate whether there is a relationship between menstrual cycle phase and exercise-induced\\u000a bronchoconstriction (EIB) in female athletes with mild atopic asthma. Seven eumenorrheic subjects with regular 28-day menstrual\\u000a cycles were exercised to volitional exhaustion on day 5 [mid-follicular (FOL)] and day 21 [mid-luteal (LUT)] of their menstrual\\u000a cycle. Pulmonary function tests were

Kristin I. Stanford; Timothy D. Mickleborough; Shahla Ray; Martin R. Lindley; David M. Koceja; Joel M. Stager

2006-01-01

70

Shortening tobacco life cycle accelerates functional gene identification in genomic research.  

PubMed

Definitive allocation of function requires the introduction of genetic mutations and analysis of their phenotypic consequences. Novel, rapid and convenient techniques or materials are very important and useful to accelerate gene identification in functional genomics research. Here, over-expression of PmFT (Prunus mume), a novel FT orthologue, and PtFT (Populus tremula) lead to shortening of the tobacco life cycle. A series of novel short life cycle stable tobacco lines (30-50 days) were developed through repeated self-crossing selection breeding. Based on the second transformation via a gusA reporter gene, the promoter from BpFULL1 in silver birch (Betula pendula) and the gene (CPC) from Arabidopsis thaliana were effectively tested using short life cycle tobacco lines. Comparative analysis among wild type, short life cycle tobacco and Arabidopsis transformation system verified that it is optional to accelerate functional gene studies by shortening host plant material life cycle, at least in these short life cycle tobacco lines. The results verified that the novel short life cycle transgenic tobacco lines not only combine the advantages of economic nursery requirements and a simple transformation system, but also provide a robust, effective and stable host system to accelerate gene analysis. Thus, shortening tobacco life cycle strategy is feasible to accelerate heterologous or homologous functional gene identification in genomic research. PMID:23107371

Ning, G; Xiao, X; Lv, H; Li, X; Zuo, Y; Bao, M

2012-11-01

71

Physiologic responses during functional electrical stimulation leg cycling and hybrid exercise in spinal cord injured subjects  

Microsoft Academic Search

Objectives: (1) To determine if a hybrid exercise (leg plus arm) training program performed immediately after functional electrical stimulation (FES) leg cycle exercise (LCE) training would further improve aerobic capacity when compared with FES leg cycle training alone, and (2) to compare the submaximal responses occurring during both FES-LCE alone and hybrid exercise in the same SCI subjects.Design: Nonrandomized control

Deborah L. Mutton; A. M. Erika Scremin; Thomas J. Barstow; Michael D. Scott; Charles F. Kunkel; Thomas G. Cagle

1997-01-01

72

Evaluation of Functional Electrical Stimulation to Assist Cycling in Four Adolescents with Spastic Cerebral Palsy  

PubMed Central

Introduction. Adolescents with cerebral palsy (CP) often have difficulty participating in exercise at intensities necessary to improve cardiovascular fitness. Functional electrical stimulation- (FES-) assisted cycling is proposed as a form of exercise for adolescents with CP. The aims of this paper were to adapt methods and assess the feasibility of applying FES cycling technology in adolescents with CP, determine methods of performing cycling tests in adolescents with CP, and evaluate the immediate effects of FES assistance on cycling performance. Materials/Methods. Four participants (12–14 years old; GMFCS levels III-IV) participated in a case-based pilot study of FES-assisted cycling in which bilateral quadriceps muscles were activated using surface electrodes. Cycling cadence, power output, and heart rate were collected. Results. FES-assisted cycling was well tolerated (n = 4) and cases are presented demonstrating increased cadence (2–43?rpm), power output (19–70%), and heart rates (4-5%) and decreased variability (8–13%) in cycling performance when FES was applied, compared to volitional cycling without FES assistance. Some participants (n = 2) required the use of an auxiliary hub motor for assistance. Conclusions. FES-assisted cycling is feasible for individuals with CP and may lead to immediate improvements in cycling performance. Future work will examine the potential for long-term fitness gains using this intervention. PMID:22685479

Harrington, Ann Tokay; McRae, Calum G. A.; Lee, Samuel C. K.

2012-01-01

73

Molecular structure and spectral properties of ethyl 3-quinolinecarboxylate (E3Q) and [Ag(E3Q)2(TCA)] complex (TCA=Trichloroacetate).  

PubMed

A new [Ag(E3Q)2(TCA)] complex; (E3Q=Ethyl 3-quinolinecarboxylate and TCA=Trichloroacetate) has been synthesized and characterized using elemental analysis, FTIR, NMR and mass spectroscopy. The molecular geometry and spectroscopic properties of the complex as well as the free ligand have been calculated using the hybrid B3LYP method. The calculations predicted a distorted tetrahedral arrangement around Ag(I) ion. The vibrational spectra of the studied compounds have been assigned using potential energy distribution (PED). TD-DFT method was used to predict the electronic absorption spectra. The most intense absorption band showed a bathochromic shift and lowering of intensity in case of the complex (233.7 nm, f=0.5604) compared to E3Q (?max=228.0 nm, f=0.9072). The calculated (1)H NMR chemical shifts using GIAO method showed good correlations with the experimental data. The computed dipole moment, polarizability and HOMO-LUMO energy gap were used to predict the nonlinear optical (NLO) properties. It is found that Ag(I) enhances the NLO activity. The natural bond orbital (NBO) analyses were used to elucidate the intramolecular charge transfer interactions causing stabilization for the investigated systems. PMID:24813274

Soliman, Saied M; Kassem, Taher S; Badr, Ahmed M A; Abou Youssef, Morsy A; Assem, Rania

2014-09-15

74

Status report on a MicroTCA card for HCAL trigger and readout at SLHC  

NASA Astrophysics Data System (ADS)

We present recent measurements performed using a prototype MicroTCA card for CMS-HCAL Trigger and Readout at SLHC. Our second generation prototype uses a Xilinx XC5VFX70T FPGA to perform the high-speed communication and data processing for up to eight Readout Module fibers that are streaming data at 4.8 Gbps each. The FPGA also uses two SFP+ optical interfaces at 6.4 Gbps each for data transfer to the Trigger System. A local DAQ interface in the FPGA communicates via Gigabit Ethernet with the MicroTCA MCH. Bit Error Rate Test (BERT) results and data integrity analyses are presented in challenging clocking environments including a legacy TTC system. In addition, the status of the IPbus concept for control of deeply embedded devices is presented.

Mans, J.; Frahm, E.

2010-12-01

75

Status report on a MicroTCA card for HCAL trigger and readout at SLHC  

E-print Network

We present recent measurements performed using a prototype MicroTCA card for CMS-HCAL Trigger and Readout at SLHC. Our second generation prototype uses a Xilinx XC5VFX70T FPGA to perform the high-speed communication and data processing for up to eight Readout Module fibers that are streaming data at 4.8 Gbps each. The FPGA also uses two SFP+ optical interfaces at 6.4 Gbps each for data transfer to the Trigger System. A local DAQ interface in the FPGA communicates via Gigabit Ethernet with the MicroTCA MCH. Bit Error Rate Test (BERT) results and data integrity analyses are presented in challenging clocking environments including a legacy TTC system. In addition, the status of the IPbus concept for control of deeply embedded devices is presented

Mans, J; 10.1088/1748-0221/5/12/C12027

2010-01-01

76

The functional cycle of visual arrestins in photoreceptor cells  

PubMed Central

Visual arrestin-1 plays a key role in the rapid and reproducible shutoff of rhodopsin signaling. Its highly selective binding to light-activated phosphorylated rhodopsin is an integral part of the functional perfection of rod photoreceptors. Structure-function studies revealed key elements of the sophisticated molecular mechanism ensuring arrestin-1 selectivity and paved the way to the targeted manipulation of the arrestin-1 molecule to design mutants that can compensate for congenital defects in rhodopsin phosphorylation. Arrestin-1 self-association and light-dependent translocation in photoreceptor cells work together to keep a constant supply of active rhodopsin-binding arrestin-1 monomer in the outer segment. Recent discoveries of arrestin-1 interaction with other signaling proteins suggest that it is a much more versatile signaling regulator than previously thought, affecting the function of the synaptic terminals and rod survival. Elucidation of the fine molecular mechanisms of arrestin-1 interactions with rhodopsin and other binding partners is necessary for the comprehensive understanding of rod function and for devising novel molecular tools and therapeutic approaches to the treatment of visual disorders. PMID:21824527

Gurevich, Vsevolod V.; Hanson, Susan M.; Song, Xiufeng; Vishnivetskiy, Sergey A.; Gurevich, Eugenia V.

2011-01-01

77

Impact of Polyphenol Antioxidants on Cycling Performance and Cardiovascular Function  

PubMed Central

This investigation sought to determine if supplementation with polyphenol antioxidant (PA) improves exercise performance in the heat (31.5 °C, 55% RH) by altering the cardiovascular and thermoregulatory responses to exercise. Twelve endurance trained athletes ingested PA or placebo (PLAC) for 7 days. Consecutive days of exercise testing were performed at the end of the supplementation periods. Cardiovascular and thermoregulatory measures were made during exercise. Performance, as measured by a 10 min time trial (TT) following 50 min of moderate intensity cycling, was not different between treatments (PLAC: 292 ± 33 W and PA: 279 ± 38 W, p = 0.12). Gross efficiency, blood lactate, maximal neuromuscular power, and ratings of perceived exertion were also not different between treatments. Similarly, performance on the second day of testing, as assessed by time to fatigue at maximal oxygen consumption, was not different between treatments (PLAC; 377 ± 117 s vs. PA; 364 ± 128 s, p = 0.61). Cardiovascular and thermoregulatory responses to exercise were not different between treatments on either day of exercise testing. Polyphenol antioxidant supplementation had no impact on exercise performance and did not alter the cardiovascular or thermoregulatory responses to exercise in the heat. PMID:24667134

Trinity, Joel D.; Pahnke, Matthew D.; Trombold, Justin R.; Coyle, Edward F.

2014-01-01

78

Interrelationships among morphology, echotexture, and function of the bovine corpus luteum during the estrous cycle  

Microsoft Academic Search

It has been suggested that ultrasound image attributes are a potential indicator of physiological and functional status of the corpus luteum (CL) in several species, including cattle. The aims of this study were to evaluate CL morphological, functional and echotextural characteristics, and also to investigate the hypothesis that those attributes are correlated and change similarly throughout an estrous cycle. Ovaries

Luiz Gustavo B. Siqueira; Ciro A. A. Torres; Lincoln S. Amorim; Eliza D. Souza; Luiz Sérgio A. Camargo; Carlos A. C. Fernandes; João Henrique M. Viana

2009-01-01

79

Menstrual Cycle-Related Changes of Functional Cerebral Asymmetries in Fine Motor Coordination  

ERIC Educational Resources Information Center

Fluctuating sex hormone levels during the menstrual cycle have been shown to affect functional cerebral asymmetries in cognitive domains. These effects seem to result from the neuromodulatory properties of sex hormones and their metabolites on interhemispheric processing. The present study was carried out to investigate whether functional cerebral…

Bayer, Ulrike; Hausmann, Markus

2012-01-01

80

Dwell Time and Surface Parameter Effects on Removal of Silicone Oil From D6ac Steel Using TCA  

NASA Technical Reports Server (NTRS)

This study was conducted to evaluate the impact of dwell time, surface roughness, and the surface activation state on 1,1,1-trichloroethane's (TCA's) effectiveness for removing silicone oil from D6ac steel. Silicone-contaminated test articles were washed with TCA solvent, and then the surfaces were analyzed for residue, using Fourier transform infrared spectroscopy. The predominant factor affecting the ability to remove the silicone oil was surface roughness.

Boothe, R. E.

2003-01-01

81

Alternative functions of core cell cycle regulators in neuronal migration, neuronal maturation, and synaptic plasticity  

PubMed Central

Recent studies have demonstrated that boundaries separating a cycling cell from a post-mitotic neuron are not as concrete as expected. Novel and unique physiological functions in neurons have been ascribed for proteins fundamentally required for cell cycle progression and control. These “core” cell cycle regulators serve diverse post-mitotic functions that span various developmental stages of a neuron, including neuronal migration, axonal elongation, axon pruning, dendrite morphogenesis, and synaptic maturation and plasticity. In this review, we detail the non-proliferative post-mitotic roles that these cell cycle proteins have recently been reported to play, the significance of their expression in neurons, mechanistic insight when available, and future prospects. PMID:19447088

Frank, Christopher L.; Tsai, Li-Huei

2009-01-01

82

Functional product life-cycle simulation model for cost estimation in conceptual design of jet engine components  

Microsoft Academic Search

As functional (total care) products emerge in the jet engine industry, the need for product life-cycle models capable of definition and evaluation of life cycle properties increases, since functional products (FP) includes both hardware and service. Recent life-cycle models are intended for hardware products and mostly handle design and manufacturing knowledge. The aim of this article is to present a

Marcus Sandberg; Patrik Boart; Tobias Larsson

2005-01-01

83

Over-expression of Gadd45a enhances radiotherapy efficacy in human Tca8113 cell line  

Microsoft Academic Search

Aim:To investigate the effect of the growth arrest- and DNA damage-inducible Gadd45a gene on the radiosensitivity of human tongue squamous cell carcinoma cell line to ionizing radiation (IR).Methods:Short interfering ribonucleic acid (si-RNA) targeting Gadd45a or an irrelevant mRNA (nonsense si-RNA) was chemically synthesized. The constructed si-RNAs were transfected into Tca8113 cells and Gadd45a expression was determined using quantitative real-time PCR

Xiao-ying Zhang; Xun Qu; Cheng-qin Wang; Cheng-jun Zhou; Gui-xiang Liu; Feng-cai Wei; Shan-zhen Sun

2011-01-01

84

Alternating stimulation of synergistic muscles during functional electrical stimulation cycling improves endurance in persons with spinal cord injury  

E-print Network

Alternating stimulation of synergistic muscles during functional electrical stimulation cycling April 2010 Accepted 22 July 2010 Keywords: Functional electrical stimulation Spinal cord injury Paralysis Quadriceps a b s t r a c t Therapeutic effects of functional electrical stimulation (FES) cycling

Griffin, Lisa

85

Menstrual cycle influence on cognitive function and emotion processing—from a reproductive perspective  

PubMed Central

The menstrual cycle has attracted research interest ever since the 1930s. For many researchers the menstrual cycle is an excellent model of ovarian steroid influence on emotion, behavior, and cognition. Over the past years methodological improvements in menstrual cycle studies have been noted, and this review summarizes the findings of methodologically sound menstrual cycle studies in healthy women. Whereas the predominant hypotheses of the cognitive field state that sexually dimorphic cognitive skills that favor men are improved during menstrual cycle phases with low estrogen and that cognitive skills that favor women are improved during cycle phases with increased estrogen and/or progesterone, this review has not found sufficient evidence to support any of these hypotheses. Mental rotation has gained specific interest in this aspect, but a meta-analysis yielded a standardized mean difference in error rate of 1.61 (95% CI ?0.35 to 3.57), suggesting, at present, no favor of an early follicular phase improvement in mental rotation performance. Besides the sexually dimorphic cognitive skills, studies exploring menstrual cycle effects on tasks that probe prefrontal cortex function, for instance verbal or spatial working memory, have also been reviewed. While studies thus far are few, results at hand suggest improved performance at times of high estradiol levels. Menstrual cycle studies on emotional processing, on the other hand, tap into the emotional disorders of the luteal phase, and may be of relevance for women with premenstrual disorders. Although evidence at present is limited, it is suggested that emotion recognition, consolidation of emotional memories, and fear extinction is modulated by the menstrual cycle in women. With the use of functional magnetic resonance imaging, several studies report changes in brain reactivity across the menstrual cycle, most notably increased amygdala reactivity in the luteal phase. Thus, to the extent that behavioral changes have been demonstrated over the course of the menstrual cycle, the best evidence suggests that differences in sexually dimorphic tasks are small and difficult to replicate. However, emotion-related changes are more consistently found, and are better associated with progesterone than with estradiol such that high progesterone levels are associated with increased amygdala reactivity and increased emotional memory. PMID:25505380

Sundström Poromaa, Inger; Gingnell, Malin

2014-01-01

86

Representing key phytoplankton functional groups in ocean carbon cycle models: Coccolithophorids  

E-print Network

of carbon on Earth. From mid-Mesozoic time, the biologically catalyzed precipitation of calcium carbonates that areas with sea surface temperatures (SST) between 3° and 15°C, a critical irradiance between 25 and 150Representing key phytoplankton functional groups in ocean carbon cycle models: Coccolithophorids M

Kleypas, Joanie

87

The cycle problem: an intriguing periodicity to the zeros of the Riemann zeta function  

E-print Network

Summing the values of the real portion of the logarithmic integral of n^rho, where rho is one of a consecutive series of zeros of the Riemann zeta function, reveals an unexpected periodicity to the sum. This is the cycle problem.

David D. Baugh

2007-12-06

88

CHLORINATION BY-PRODUCTS IN DRINKING WATER AND MENSTRUAL CYCLE FUNCTION  

EPA Science Inventory

Chlorination by-Products in Drinking Water and Menstrual Cycle Function Gayle C. Windham1, Kirsten Waller2, Meredith Anderson2, Laura Fenster1, Pauline Mendola3, Shanna Swan4 1California Department of Health Services, Division of Environmental and Occupational Disea...

89

Expected Performance Functions for Life-Cycle Analysis of Masonry-Infilled Reinforced Concrete Frames  

Microsoft Academic Search

A study is presented about the influence of infill masonry panels on the life-cycle expected performance functions of multi-story reinforced concrete frames exposed to severe seismic hazard conditions. Quantitative information is presented about present values of expected performance functions of a group of five-story systems located at a firm ground site. The group includes a bare frame system, designed in

Roberto Pérez-Martínez; Luis Esteva

2012-01-01

90

Topology of modified helical gears and Tooth Contact Analysis (TCA) program  

NASA Technical Reports Server (NTRS)

The contents of this report covers: (1) development of optimal geometries for crowned helical gears; (2) a method for their generation; (3) tooth contact analysis (TCA) computer programs for the analysis of meshing and bearing contact of the crowned helical gears; and (4) modelling and simulation of gear shaft deflection. The developed method for synthesis was used to determine the optimal geometry for a crowned helical pinion surface and was directed to localize the bearing contact and guarantee favorable shape and a low level of transmission errors. Two new methods for generation of the crowned helical pinion surface are proposed. One is based on the application of a tool with a surface of revolution that slightly deviates from a regular cone surface. The tool can be used as a grinding wheel or as a shaver. The other is based on a crowning pinion tooth surface with predesigned transmission errors. The pinion tooth surface can be generated by a computer-controlled automatic grinding machine. The TCA program simulates the meshing and bearing contact of the misaligned gears. The transmission errors are also determined. The gear shaft deformation was modelled and investigated. It was found that the deflection of gear shafts has the same effect as gear misalignment.

Litvin, Faydor L.; Zhang, Jiao

1989-01-01

91

Spur gears: Optimal geometry, methods for generation and Tooth Contact Analysis (TCA) program  

NASA Technical Reports Server (NTRS)

The contents of this report include the following: (1) development of optimal geometry for crowned spur gears; (2) methods for their generation; and (3) tooth contact analysis (TCA) computer programs for the analysis of meshing and bearing contact on the crowned spur gears. The method developed for synthesis is used for the determination of the optimal geometry for crowned pinion surface and is directed to reduce the sensitivity of the gears to misalignment, localize the bearing contact, and guarantee the favorable shape and low level of the transmission errors. A new method for the generation of the crowned pinion surface has been proposed. This method is based on application of the tool with a surface of revolution that slightly deviates from a regular cone surface. The tool can be used as a grinding wheel or as a shaver. The crowned pinion surface can also be generated by a generating plane whose motion is provided by an automatic grinding machine controlled by a computer. The TCA program simulates the meshing and bearing contact of the misaligned gears. The transmission errors are also determined.

Litvin, Faydor L.; Zhang, Jiao

1988-01-01

92

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) mixture toxicity to the macrophytes Myriophyllum spicatum and Myriophyllum sibiricum in aquatic microcosms.  

PubMed

Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) have been detected together in environmental water samples throughout the world. TCA may enter into aquatic systems via rainout as the degradation product of chlorinated solvents, herbicide use, as a by-product of water disinfection and from emissions of spent bleach liquor of kraft pulp mills. Sources of TFA include degradation of hydrofluorocarbons (HFCs) refrigerants and pesticides. These substances are phytotoxic and widely distributed in aquatic environments. A study to assess the risk of a binary mixture of TCA and TFA to macrophytes in aquatic microcosms was conducted as part of a larger study on haloacetic acids. M. spicatum and M. sibiricum were exposed to 0.1, 1, 3 and 10 mg/l of both TCA and TFA (neutralized with sodium hydroxide) in replicate (n = 3) 12000 l aquatic microcosms for 49 days in an one-way analysis of variance design. Each microcosm was stocked with 14 individual apical shoots per species. The plants were sampled at regular intervals and assessed for the somatic endpoints of plant length, root growth, number of nodes and wet and dry mass and the biochemical endpoints of chlorophyll-a, chlorophyll-b, carotenoid content and citric acid levels. Results indicate that there were statistically significant effects of the TCA/TFA mixture on certain pigment concentrations immediately after the start of exposure (2-7 days), but the plants showed no signs of stress thereafter. These data suggest that TCA/TFA mixtures at environmentally relevant concentrations do not pose a significant risk to these aquatic macrophytes. PMID:11878273

Hanson, Mark L; Sibley, Paul K; Mabury, Scott A; Solomon, Keith R; Muir, Derek C G

2002-02-21

93

Genetic Investigation of Tricarboxylic Acid Metabolism during the Plasmodium falciparum Life Cycle.  

PubMed

New antimalarial drugs are urgently needed to control drug-resistant forms of the malaria parasite Plasmodium falciparum. Mitochondrial electron transport is the target of both existing and new antimalarials. Herein, we describe 11 genetic knockout (KO) lines that delete six of the eight mitochondrial tricarboxylic acid (TCA) cycle enzymes. Although all TCA KOs grew normally in asexual blood stages, these metabolic deficiencies halted life-cycle progression in later stages. Specifically, aconitase KO parasites arrested as late gametocytes, whereas ?-ketoglutarate-dehydrogenase-deficient parasites failed to develop oocysts in the mosquitoes. Mass spectrometry analysis of (13)C-isotope-labeled TCA mutant parasites showed that P. falciparum has significant flexibility in TCA metabolism. This flexibility manifested itself through changes in pathway fluxes and through altered exchange of substrates between cytosolic and mitochondrial pools. Our findings suggest that mitochondrial metabolic plasticity is essential for parasite development. PMID:25843709

Ke, Hangjun; Lewis, Ian A; Morrisey, Joanne M; McLean, Kyle J; Ganesan, Suresh M; Painter, Heather J; Mather, Michael W; Jacobs-Lorena, Marcelo; Llinás, Manuel; Vaidya, Akhil B

2015-04-01

94

Effect of fluid ingestion on neuromuscular function during prolonged cycling exercise  

PubMed Central

Objectives: To investigate the effects of fluid ingestion on neuromuscular function during prolonged cycling exercise. Methods: Eight well trained subjects exercised for 180 minutes in a moderate environment at a workload requiring ?60% maximal oxygen uptake. Two conditions, fluid (F) and no fluid (NF) ingestion, were investigated. Results: During maximal voluntary isometric contraction (MVC), prolonged cycling exercise reduced (p<0.05) the maximal force generating capacity of quadriceps muscles (after three hours of cycling) and root mean square (RMS) values (after two hours of cycling) with no difference between the two conditions despite greater body weight loss (p<0.05) in NF. The mean power frequency (MPF) for vastus lateralis muscle was reduced (p<0.05) and the rate of force development (RFD) was increased (p<0.05) only during NF. During cycling exercise, integrated electromyographic activity and perceived exertion were increased in both conditions (p<0.05) with no significant effect of fluid ingestion. Conclusions: The results suggest that fluid ingestion did not prevent the previously reported decrease in maximal force with exercise duration, but seems to have a positive effect on some indicators of neuromuscular fatigue such as mean power frequency and rate of force development during maximal voluntary contraction. Further investigations are needed to assess the effect of change in hydration on neural mechanisms linked to the development of muscular fatigue during prolonged exercise. PMID:15793075

Vallier, J; Grego, F; Basset, F; Lepers, R; Bernard, T; Brisswalter, J

2005-01-01

95

Integrative functional genomics of hepatitis C virus infection identifies host dependencies in complete viral replication cycle.  

PubMed

Recent functional genomics studies including genome-wide small interfering RNA (siRNA) screens demonstrated that hepatitis C virus (HCV) exploits an extensive network of host factors for productive infection and propagation. How these co-opted host functions interact with various steps of HCV replication cycle and exert pro- or antiviral effects on HCV infection remains largely undefined. Here we present an unbiased and systematic strategy to functionally interrogate HCV host dependencies uncovered from our previous infectious HCV (HCVcc) siRNA screen. Applying functional genomics approaches and various in vitro HCV model systems, including HCV pseudoparticles (HCVpp), single-cycle infectious particles (HCVsc), subgenomic replicons, and HCV cell culture systems (HCVcc), we identified and characterized novel host factors or pathways required for each individual step of the HCV replication cycle. Particularly, we uncovered multiple HCV entry factors, including E-cadherin, choline kinase ?, NADPH oxidase CYBA, Rho GTPase RAC1 and SMAD family member 6. We also demonstrated that guanine nucleotide binding protein GNB2L1, E2 ubiquitin-conjugating enzyme UBE2J1, and 39 other host factors are required for HCV RNA replication, while the deubiquitinating enzyme USP11 and multiple other cellular genes are specifically involved in HCV IRES-mediated translation. Families of antiviral factors that target HCV replication or translation were also identified. In addition, various virologic assays validated that 66 host factors are involved in HCV assembly or secretion. These genes included insulin-degrading enzyme (IDE), a proviral factor, and N-Myc down regulated Gene 1 (NDRG1), an antiviral factor. Bioinformatics meta-analyses of our results integrated with literature mining of previously published HCV host factors allows the construction of an extensive roadmap of cellular networks and pathways involved in the complete HCV replication cycle. This comprehensive study of HCV host dependencies yields novel insights into viral infection, pathogenesis and potential therapeutic targets. PMID:24852294

Li, Qisheng; Zhang, Yong-Yuan; Chiu, Stephan; Hu, Zongyi; Lan, Keng-Hsin; Cha, Helen; Sodroski, Catherine; Zhang, Fang; Hsu, Ching-Sheng; Thomas, Emmanuel; Liang, T Jake

2014-05-01

96

Feasibility of home-based functional electrical stimulation cycling: case report  

Microsoft Academic Search

Study design:Single-subject (male, 64 years of age) case.Objectives:To determine the feasibility of a home-based FES-LEC (functional electrical stimulation lower extremities cycling) program and effects on body composition, quality of life (QOL) and seat pressure mapping in an older individual with spinal cord injured (SCI).Setting:Home-based FES-LEC with internet connection. Southeastern United States.Methods:FES-LEC three sessions per week for 9 weeks in the

D R Dolbow; A S Gorgey; D X Cifu; J R Moore; D R Gater

2012-01-01

97

Cellular and functional characterization of buffalo (Bubalus bubalis) corpus luteum during the estrous cycle and pregnancy.  

PubMed

In the present paper, cellular composition of buffalo corpus luteum (CL) with its functional characterization based on 3?-HSD and progesterone secretory ability at different stages of estrous cycle and pregnancy was studied. Buffalo uteri along with ovaries bearing CL were collected from the local slaughter house. These were classified into different stages of estrous cycle (Stage I, II, III and IV) and pregnancy (Stage I, II and III) based on morphological appearance of CL, surface follicles on the ovary and crown rump length of conceptus. Luteal cell population, progesterone content and steroidogenic properties were studied by dispersion of luteal cells using collagenase type I enzyme, RIA and 3?-HSD activity, respectively. Large luteal cells (LLC) appeared as polyhedral or spherical in shape with a centrally placed large round nucleus and an abundance of cytoplasmic lipid droplets. However, small luteal cells (SLC) appeared to be spindle shaped with an eccentrically placed irregular nucleus and there was paucity of cytoplasmic lipid droplets. The size of SLC (range 12-23?m) and LLC (range 25-55?m) increased (P<0.01) with the advancement of stage of estrous cycle and pregnancy. The mean progesterone concentration per gram and per CL increased (P<0.01) from Stage I to III of estrous cycle with maximum concentration at Stage III of estrous cycle and pregnancy. The progesterone concentration decreased at Stage IV (day 17-20) of estrous cycle coinciding with CL regression. Total luteal cell number (LLC and SLC) also increased (P<0.01) from Stage I to III of estrous cycle and decreased (P<0.05), thereafter, at Stage IV indicating degeneration of luteal cells and regression of the CL. Total luteal cell population during pregnancy also increased (P<0.01) from Stage I to II and thereafter decreased (P>0.05) indicating cessation of mitosis. Increased (P<0.05) large luteal cell numbers from Stage I to III of estrous cycle and pregnancy coincided with the increased progesterone secretion and 3?-HSD activity of CL. Thus, proportionate increases of large compared with small luteal cells were primarily responsible for increased progesterone secretion during the advanced stages of the estrous cycle and pregnancy. Total luteal cells and progesterone content per CL during the mid-luteal stage in buffalo as observed in the present study seem to be less than with cattle suggesting inherent luteal deficiency. PMID:23896394

Baithalu, Rubina Kumari; Singh, S K; Gupta, Chhavi; Raja, Anuj K; Saxena, Abhishake; Kumar, Yogendra; Singh, R; Agarwal, S K

2013-08-01

98

Functional unit, technological dynamics, and scaling properties for the life cycle energy of residences.  

PubMed

Prior LCA studies take the operational phase to include all energy use within a residence, implying a functional unit of all household activities, but then exclude related supply chains such as production of food, appliances, and household chemicals. We argue that bounding the functional unit to provision of a climate controlled space better focuses the LCA on the building, rather than activities that occur within a building. The second issue explored in this article is how technological change in the operational phase affects life cycle energy. Heating and cooling equipment is replaced at least several times over the lifetime of a residence; improved efficiency of newer equipment affects life cycle energy use. The third objective is to construct parametric models to describe LCA results for a family of related products. We explore these three issues through a case study of energy use of residences: one-story and two-story detached homes, 1,500-3,500 square feet in area, located in Phoenix, Arizona, built in 2002 and retired in 2051. With a restricted functional unit and accounting for technological progress, approximately 30% of a building's life cycle energy can be attributed to materials and construction, compared to 0.4-11% in previous studies. PMID:22192002

Frijia, Stephane; Guhathakurta, Subhrajit; Williams, Eric

2012-02-01

99

Sexual dimorphism in immune function changes during the annual cycle in house sparrows  

NASA Astrophysics Data System (ADS)

Difference between sexes in parasitism is a common phenomenon among birds, which may be related to differences between males and females in their investment into immune functions or as a consequence of differential exposure to parasites. Because life-history strategies change sex specifically during the annual cycle, immunological responses of the host aiming to reduce the impact of parasites may be sexually dimorphic. Despite the great complexity of the immune system, studies on immunoecology generally characterise the immune status through a few variables, often overlooking potentially important seasonal and gender effects. However, because of the differences in physiological and defence mechanisms among different arms of the immune system, we expect divergent responses of immune components to environmental seasonality. In male and female house sparrows ( Passer domesticus), we measured the major components of the immune system (innate, acquired, cellular and humoral) during four important life-history stages across the year: (1) mating, (2) breeding, (3) moulting and (4) during the winter capture and also following introduction to captivity in aviary. Different individuals were sampled from the same population during the four life cycle stages. We found that three out of eight immune variables showed a significant life cycle stage × sex interaction. The difference in immune response between the sexes was significant in five immune variables during the mating stage, when females had consistently stronger immune function than males, while variables varied generally non-significantly with sex during the remaining three life cycle stages. Our results show that the immune system is highly variable between life cycle stages and sexes, highlighting the potential fine tuning of the immune system to specific physiological states and environmental conditions.

Pap, Péter László; Czirják, Gábor Árpád; Vágási, Csongor István; Barta, Zoltán; Hasselquist, Dennis

2010-10-01

100

TcA, the putative transposase of the C. elegans Tc1 transposon, has an N-terminal DNA binding domain.  

PubMed Central

Tc1 is a transposon present in several copies in the genome of all natural isolates of the nematode C.elegans; it is actively transposing in many strains. In those strains Tc1 insertion is the main cause of spontaneous mutations. The transposon contains one large ORF that we call TcA; we assume that the TcA protein is the transposase of Tc1. We expressed TcA in E.coli, purified the protein and showed that it has a strong affinity for DNA (both single stranded and double stranded). A fusion protein of beta-galactosidase and TcA also exhibits DNA binding; deletion derivatives of this fusion protein were tested for DNA binding. A deletion of 39 amino acids at the N-terminal region of TcA abolishes the DNA binding, whereas a deletion of 108 C-terminal amino acids does not affect DNA binding. This shows that the DNA binding domain of TcA is near the N-terminal region. The DNA binding capacity of TcA supports the assumption that TcA is a transposase of Tc1. Images PMID:2156234

Schukkink, R F; Plasterk, R H

1990-01-01

101

Extraction-less, rapid assay for the direct detection of 2,4,6-trichloroanisole (TCA) in cork samples.  

PubMed

2,4,6-trichloroanisole (TCA), the cork taint molecule, has been the target of several analytical approaches over the few past years. In spite of the development of highly efficient and sensitive tools for its detection, ranging from advanced chromatography to biosensor-based techniques, a practical breakthrough for routine cork screening purposes has not yet been realized, in part due to the requirement of a lengthy extraction of TCA in organic solvents, mostly 12% ethanol and the high detectability required. In the present report, we present a modification of a previously reported biosensor system based on the measurement of the electric response of cultured fibroblast cells membrane-engineered with the pAb78 TCA-specific antibody. Samples were prepared by macerating cork tissue and mixing it directly with the cellular biorecognition elements, without any intervening extraction process. By using this novel approach, we were able to detect TCA in just five minutes at extremely low concentrations (down to 0.2 ppt). The novel biosensor offers a number of practical benefits, including a very considerable reduction in the total assay time by one day, and a full portability, enabling its direct employment for on-site, high throughput screening of cork in the field and production facilities, without requiring any type of supporting infrastructure. PMID:24840453

Apostolou, Theofylaktos; Pascual, Nuria; Marco, M-Pilar; Moschos, Anastassios; Petropoulos, Anastassios; Kaltsas, Grigoris; Kintzios, Spyridon

2014-07-01

102

Fabrication of functionally gradient nanocomposite coatings by plasma electrolytic oxidation based on variable duty cycle  

NASA Astrophysics Data System (ADS)

Plasma electrolytic oxidation (PEO) was applied on the surface of commercially pure titanium substrates in a mixed aluminate-phosphate electrolyte in the presence of silicon nitride nanoparticles as suspension in the electrolyte in order to fabricate nanocomposite coatings. Pulsed current was applied based on variable duty cycle in order to synthesize functionally gradient coatings (FGC). Different rates of variable duty cycle (3, 1.5 and 1%/min), applied current densities (0.06-0.14 A/cm2) and concentrations of nanoparticles in the electrolyte (2, 4, 6, 8 and 10 g l-1) were investigated. The nanopowder and coated samples were analyzed by atomic force microscope, scanning electron microscope and transmission electron microscope. The influence of different rates of variable duty cycle (or treatment times) on the growth rate of nanocomposite coatings and their microhardness values was investigated. The experimental results revealed that the content of Si3N4 nanoparticulates in the layer increases with the increase of its concentration in the plasma electrolysis bath. Nanocomposite coatings fabricated with lower rate of variable duty cycle have higher microhardness with smoother microhardness profile.

Aliofkhazraei, M.; Rouhaghdam, A. Sabour

2012-01-01

103

Biostimulation induces syntrophic interactions that impact C, S and N cycling in a sediment microbial community.  

PubMed

Stimulation of subsurface microorganisms to induce reductive immobilization of metals is a promising approach for bioremediation, yet the overall microbial community response is typically poorly understood. Here we used proteogenomics to test the hypothesis that excess input of acetate activates complex community functioning and syntrophic interactions among autotrophs and heterotrophs. A flow-through sediment column was incubated in a groundwater well of an acetate-amended aquifer and recovered during microbial sulfate reduction. De novo reconstruction of community sequences yielded near-complete genomes of Desulfobacter (Deltaproteobacteria), Sulfurovum- and Sulfurimonas-like Epsilonproteobacteria and Bacteroidetes. Partial genomes were obtained for Clostridiales (Firmicutes) and Desulfuromonadales-like Deltaproteobacteria. The majority of proteins identified by mass spectrometry corresponded to Desulfobacter-like species, and demonstrate the role of this organism in sulfate reduction (Dsr and APS), nitrogen fixation and acetate oxidation to CO2 during amendment. Results indicate less abundant Desulfuromonadales, and possibly Bacteroidetes, also actively contributed to CO2 production via the tricarboxylic acid (TCA) cycle. Proteomic data indicate that sulfide was partially re-oxidized by Epsilonproteobacteria through nitrate-dependent sulfide oxidation (using Nap, Nir, Nos, SQR and Sox), with CO2 fixed using the reverse TCA cycle. We infer that high acetate concentrations, aimed at stimulating anaerobic heterotrophy, led to the co-enrichment of, and carbon fixation in Epsilonproteobacteria. Results give an insight into ecosystem behavior following addition of simple organic carbon to the subsurface, and demonstrate a range of biological processes and community interactions were stimulated. PMID:23190730

Handley, Kim M; VerBerkmoes, Nathan C; Steefel, Carl I; Williams, Kenneth H; Sharon, Itai; Miller, Christopher S; Frischkorn, Kyle R; Chourey, Karuna; Thomas, Brian C; Shah, Manesh B; Long, Philip E; Hettich, Robert L; Banfield, Jillian F

2013-04-01

104

Modeling the High Speed Research Cycle 2B Longitudinal Aerodynamic Database Using Multivariate Orthogonal Functions  

NASA Technical Reports Server (NTRS)

The data for longitudinal non-dimensional, aerodynamic coefficients in the High Speed Research Cycle 2B aerodynamic database were modeled using polynomial expressions identified with an orthogonal function modeling technique. The discrepancy between the tabular aerodynamic data and the polynomial models was tested and shown to be less than 15 percent for drag, lift, and pitching moment coefficients over the entire flight envelope. Most of this discrepancy was traced to smoothing local measurement noise and to the omission of mass case 5 data in the modeling process. A simulation check case showed that the polynomial models provided a compact and accurate representation of the nonlinear aerodynamic dependencies contained in the HSR Cycle 2B tabular aerodynamic database.

Morelli, E. A.; Proffitt, M. S.

1999-01-01

105

Acute Bouts of Assisted Cycling Improves Cognitive and Upper Extremity Movement Functions in Adolescents with Down Syndrome  

ERIC Educational Resources Information Center

The aim of this study was to examine the effectiveness of 2 modes of exercise on cognitive and upper extremity movement functioning in adolescents with Down syndrome (DS). Nine participants randomly completed 3 interventions over 3 consecutive weeks. The interventions were: (a) voluntary cycling (VC), in which participants cycled at their…

Ringenbach, Shannon D. R; Albert, Andrew R.; Chen, Chih-Chia; Alberts, Jay L.

2014-01-01

106

Inter-limb changes in arterial function after intense cycling exercise.  

PubMed

We investigated whether muscle exercise, by inducing a subsequent local response, alters local and systemic arterial function differently. Eleven healthy volunteers (31±8 years) performed a 45-min cycling session at a heart rate corresponding to 10% above ventilatory threshold. Measurements were performed before and 45?min after exercise. Central and peripheral blood pressures were assessed by applanation tonometry and automatic sphygmomanometer, respectively. Brachial and popliteal arterial changes in diameter and blood flow were assessed using ultrasonography. The endothelium-dependent function was assessed simultaneously on brachial and popliteal arteries by flow-mediated dilation. Systolic blood pressure decreased significantly in both upper and lower limbs as well as centrally. Ankle-brachial index decreased significantly. Cross-sectional area and blood flow of popliteal and brachial arteries increased significantly. The increase in blood flow was higher in the brachial than in the popliteal artery, whereas diameter increase was of similar magnitude between the two arteries. When normalized with shear rate, brachial flow-mediated dilation was significantly greater, whereas popliteal flow-mediated dilation was similar post- vs. pre-exercise. After an acute bout of intense cycling, blood flow increase and endothelial function were greater in the non-exercised upper limb compared to the exercised lower limb, suggesting that anaerobic exercise blunts the enhancement of systemic endothelium-dependant vasodilation in active muscle beds. PMID:24886921

Rossi, P; Gargne, O; Ayme, K; Gavarry, O; Boussuges, A

2014-10-01

107

Oral contraceptive pill use and menstrual cycle phase are associated with altered resting state functional connectivity.  

PubMed

At rest, brain activity can be characterized not by an absence of organized activity but instead by spatially and temporally correlated patterns of activity. In this experiment, we investigated whether and to what extent resting state functional connectivity is modulated by sex hormones in women, both across the menstrual cycle and when altered by oral contraceptive pills. Sex hormones have been shown to have important effects on task-related activity, but few studies have investigated the extent to which they can influence the behavior of functional networks at rest. These hormones are dramatically altered by the use of hormonal contraception, which is used by approximately 100 million women worldwide. However, potential cognitive side effects of hormonal contraception have been given little attention. Here, we collected resting state data for naturally-cycling women (n=45) and women using combined oral contraceptive pills (n=46) and evaluated the differences in resting state activity between these two groups using independent component analysis. We found that in the default mode network and in a network associated with executive control, resting state dynamics were altered both by the menstrual cycle and by oral contraceptive use. Specifically, the connectivity of the left angular gyrus, the left middle frontal gyrus, and the anterior cingulate cortex were different between groups. Because the anterior cingulate cortex and left middle frontal gyrus are important for higher-order cognitive and emotional processing, including conflict monitoring, changes in the relationship of these structures to the functional networks with which they interact may have important consequences for attention, affect, and/or emotion regulation. PMID:24365676

Petersen, Nicole; Kilpatrick, Lisa A; Goharzad, Azaadeh; Cahill, Larry

2014-04-15

108

Adenosine kinase deficiency disrupts the methionine cycle and causes hypermethioninemia, encephalopathy, and abnormal liver function.  

PubMed

Four inborn errors of metabolism (IEMs) are known to cause hypermethioninemia by directly interfering with the methionine cycle. Hypermethioninemia is occasionally discovered incidentally, but it is often disregarded as an unspecific finding, particularly if liver disease is involved. In many individuals the hypermethioninemia resolves without further deterioration, but it can also represent an early sign of a severe, progressive neurodevelopmental disorder. Further investigation of unclear hypermethioninemia is therefore important. We studied two siblings affected by severe developmental delay and liver dysfunction. Biochemical analysis revealed increased plasma levels of methionine, S-adenosylmethionine (AdoMet), and S-adenosylhomocysteine (AdoHcy) but normal or mildly elevated homocysteine (Hcy) levels, indicating a block in the methionine cycle. We excluded S-adenosylhomocysteine hydrolase (SAHH) deficiency, which causes a similar biochemical phenotype, by using genetic and biochemical techniques and hypothesized that there was a functional block in the SAHH enzyme as a result of a recessive mutation in a different gene. Using exome sequencing, we identified a homozygous c.902C>A (p.Ala301Glu) missense mutation in the adenosine kinase gene (ADK), the function of which fits perfectly with this hypothesis. Increased urinary adenosine excretion confirmed ADK deficiency in the siblings. Four additional individuals from two unrelated families with a similar presentation were identified and shown to have a homozygous c.653A>C (p.Asp218Ala) and c.38G>A (p.Gly13Glu) mutation, respectively, in the same gene. All three missense mutations were deleterious, as shown by activity measurements on recombinant enzymes. ADK deficiency is a previously undescribed, severe IEM shedding light on a functional link between the methionine cycle and adenosine metabolism. PMID:21963049

Bjursell, Magnus K; Blom, Henk J; Cayuela, Jordi Asin; Engvall, Martin L; Lesko, Nicole; Balasubramaniam, Shanti; Brandberg, Göran; Halldin, Maria; Falkenberg, Maria; Jakobs, Cornelis; Smith, Desiree; Struys, Eduard; von Döbeln, Ulrika; Gustafsson, Claes M; Lundeberg, Joakim; Wedell, Anna

2011-10-01

109

Nitrogen cycling in Yellowstone National Park thermal features: using gene expression to reveal ecological function  

NASA Astrophysics Data System (ADS)

Studies of biodiversity, metabolic strategies, and functional ecology in modern hydrothermal systems have the potential to provide insight into the metabolism and evolution of life. The geochemical and microbial diversity present at Yellowstone National Park (YNP), Wyoming, USA, makes it an ideal place for studying the functional ecology and metabolic processes of prokaryotic organisms. While much work in terrestrial hydrothermal features is focused on phylogenetic and geochemical analyses, a few recent investigations in YNP and other hydrothermal areas have focused on “gene hunting”: screening thermal sediment and biofilm samples for the presence of genes utilized in specific metabolic processes [2, 3, 6, 7, 8]. Although research has evaluated and confirmed the presence of many of these genes in various thermophilic microbial communities, the existence of a gene in the DNA of an organism does not verify its use, and few researchers have done work to confirm the utilization (expression) of the genes discovered in thermal samples [1, 6, 7, 8]. Disequilibrium between reduced hydrothermal fluid of YNP thermal features and the atmosphere provides a copious source of potential energy to be harnessed through microbial metabolic processes, with NO3- and NO2- serving as the preferred electron acceptors and top energy sources after O2 [4, 5]. Consequentially, nitrogen cycling likely plays a vital role in microbial metabolic processes, as well as nutrient availability. This study explores the presence and utilization of functional genes that are key in steps of the nitrogen cycle, such as nitrogen fixation (NifH), denitrification (nirKS), and ammonia oxidation (amoA). Both DNA and RNA were extracted from thermal sediment and streamer biofilm communities collected in the chemosynthetic zone of various thermal features of the Sentinel Meadows Group in Lower Geyser Basin, YNP. Extracted DNA and reverse transcribed RNA (cDNA) were amplified using the polymerase chain reaction (PCR), and products were analyzed through gel electrophoresis to identify the presence and expression of the target functional nitrogen cycle genes. Results allow comparison of nitrogen cycling processes between different chemotrophic microbial communities both within and among the thermal features investigated in this study. [1] Botero et al., 2005. AEM 71: 1267-1275. [2] Hall et al., 2008. AEM 74: 4910-4922. [3] Meyer-Dombard et al., 2009. EOS Trans AGU 90. Abstract B23C-0390. [4] Reysenbach & Shock, 2002. Science 296: 1077-1082. [5] Shock et al., 2005. Geochim Cosmochim Acta 74: 4005-4043. [6] Steunou et al., 2006. PNAS 103:2398-2403. [7] Steunou et al., 2008. The ISME Journal 2: 364-378. [8] Zhang et al., 2008. AEM 74: 6417-6426.

Lafree, S. T.; Burton, M. S.; Meyer-Dombard, D. R.

2010-12-01

110

Finding Limit Cycles in self-excited oscillators with infinite-series damping functions  

NASA Astrophysics Data System (ADS)

In this paper we present a simple method for finding the location of limit cycles of self excited oscillators whose damping functions can be represented by some infinite convergent series. We have used standard results of first-order perturbation theory to arrive at amplitude equations. The approach has been kept pedagogic by first working out the cases of finite polynomials using elementary algebra. Then the method has been extended to various infinite polynomials, where the fixed points of the corresponding amplitude equations cannot be found out. Hopf bifurcations for systems with nonlinear powers in velocities have also been discussed.

Das, Debapriya; Banerjee, Dhruba; Bhattacharjee, Jayanta K.

2015-03-01

111

Functional Interaction between Phosducin-like Protein 2 and Cytosolic Chaperonin Is Essential for Cytoskeletal Protein Function and Cell Cycle Progression  

PubMed Central

The C haperonin Containing Tcp1 (CCT) maintains cellular protein folding homeostasis in the eukaryotic cytosol by assisting the biogenesis of many proteins, including actins, tubulins, and regulators of the cell cycle. Here, we demonstrate that the essential and conserved eukaryotic phosducin-like protein 2 (PhLP2/PLP2) physically interacts with CCT and modulates its folding activity. Consistent with this functional interaction, temperature-sensitive alleles of Saccharomyces cerevisiae PLP2 exhibit cytoskeletal and cell cycle defects. We uncovered several high-copy suppressors of the plp2 alleles, all of which are associated with G1/S cell cycle progression but which do not appreciably affect cytoskeletal protein function or fully rescue the growth defects. Our data support a model in which Plp2p modulates the biogenesis of several CCT substrates relating to cell cycle and cytoskeletal function, which together contribute to the essential function of PLP2. PMID:17429077

Stirling, Peter C.; Srayko, Martin; Takhar, Karam S.; Pozniakovsky, Andrei; Hyman, Anthony A.

2007-01-01

112

Sparstolonin B Inhibits Pro-Angiogenic Functions and Blocks Cell Cycle Progression in Endothelial Cells  

PubMed Central

Sparstolonin B (SsnB) is a novel bioactive compound isolated from Sparganium stoloniferum, an herb historically used in Traditional Chinese Medicine as an anti-tumor agent. Angiogenesis, the process of new capillary formation from existing blood vessels, is dysregulated in many pathological disorders, including diabetic retinopathy, tumor growth, and atherosclerosis. In functional assays, SsnB inhibited endothelial cell tube formation (Matrigel method) and cell migration (Transwell method) in a dose-dependent manner. Microarray experiments with human umbilical vein endothelial cells (HUVECs) and human coronary artery endothelial cells (HCAECs) demonstrated differential expression of several hundred genes in response to SsnB exposure (916 and 356 genes, respectively, with fold change ?2, p<0.05, unpaired t-test). Microarray data from both cell types showed significant overlap, including genes associated with cell proliferation and cell cycle. Flow cytometric cell cycle analysis of HUVECs treated with SsnB showed an increase of cells in the G1 phase and a decrease of cells in the S phase. Cyclin E2 (CCNE2) and Cell division cycle 6 (CDC6) are regulatory proteins that control cell cycle progression through the G1/S checkpoint. Both CCNE2 and CDC6 were downregulated in the microarray data. Real Time quantitative PCR confirmed that gene expression of CCNE2 and CDC6 in HUVECs was downregulated after SsnB exposure, to 64% and 35% of controls, respectively. The data suggest that SsnB may exert its anti-angiogenic properties in part by downregulating CCNE2 and CDC6, halting progression through the G1/S checkpoint. In the chick chorioallantoic membrane (CAM) assay, SsnB caused significant reduction in capillary length and branching number relative to the vehicle control group. Overall, SsnB caused a significant reduction in angiogenesis (ANOVA, p<0.05), demonstrating its ex vivo efficacy. PMID:23940584

Bateman, Henry R.; Liang, Qiaoli; Fan, Daping; Rodriguez, Vanessa; Lessner, Susan M.

2013-01-01

113

Power Effects on High Lift, Stability and Control Characteristics of the TCA Model Tested in the LaRC 14 x 22 Ft Wind Tunnel  

NASA Technical Reports Server (NTRS)

The TCA-2 wind-tunnel test was the second in a series of planned tests utilizing the 5% Technology Concept Airplane (TCA) model. Each of the tests was planned to utilize the unique capabilities of the NASA Langley 14'x22' and the NASA Ames 12' test facilities, in order to assess specific aspects of the high lift and stability and control characteristics of the TCA configuration. However, shortly after the completion of the TCA-1 test, an early projection of the Technology Configuration (TC) identified the need for several significant changes to the baseline TCA configuration. These changes were necessary in order to meet more stringent noise certification levels, as well as, to provide a means to control dynamic structural modes. The projected changes included a change to the outboard wing (increased aspect ratio and lower sweep) and a reconfiguration of the longitudinal control surfaces to include a medium size canard and a reduced horizontal tail. The impact of these proposed changes did not affect the TCA-2 test, because it was specifically planned to address power effects on the empennage and a smaller horizontal tail was in the plan to be tested. However, the focus of future tests was reevaluated and the emphasis was shifted away from assessment of TCA specific configurations to a more general assessment of configurations that encompass the projected design space for the TC.

Glessner, Paul T.

1999-01-01

114

The Functional Breakdown Structure (FBS) and Its Relationship to Life Cycle Cost  

NASA Technical Reports Server (NTRS)

The Functional Breakdown Structure (FBS) is a structured, modular breakdown of every function that must be addressed to perform a generic mission. It is also usable for any subset of the mission. Unlike a Work Breakdown Structure (WBS), the FBS is a function-oriented tree, not a product-oriented tree. The FBS details not products, but operations or activities that should be performed. The FBS is not tied to any particular architectural implementation because it is a listing of the needed functions, not the elements, of the architecture. The FBS for Space Transportation Systems provides a universal hierarchy of required functions, which include ground and space operations as well as infrastructure - it provides total visibility of the entire mission. By approaching the systems engineering problem from the functional view, instead of the element or hardware view, the SPST has created an exhaustive list of potential requirements which the architecture designers can use to evaluate the completeness of their designs. This is a new approach that will provide full accountability of all functions required to perform the planned mission. It serves as a giant check list to be sure that no functions are omitted, especially in the early architectural design phase. A significant characteristic of a FBS is that if architecture options are compared using this approach, then any missing or redundant elements of each option will be ' identified. Consequently, valid Life Cycle Costs (LCC) comparisons can be made. For example, one architecture option might not need a particular function while another option does. One option may have individual elements to perform each of three functions while another option needs only one element to perform the three functions. Once an architecture has been selected, the FBS will serve as a guide in development of the work breakdown structure, provide visibility of those technologies that need to be further developed to perform required functions, and help identify the personnel skills required to develop and operate the architecture. It also wifi allow the systems engineering activities to totally integrate each discipline to the maximum extent possible and optimize at the total system level, thus avoiding optimizing at the element level (stove-piping). In addition, it furnishes a framework that wifi help prevent over or under specifying requirements because all functions are identified and all elements are aligned to functions.

DeHoff, Bryan; Levack, Danie J. H.; Rhodes, Russell E.

2009-01-01

115

An Estimate of the Size and Shape of Sunspot Cycle 24 Based on its Early Cycle Behavior using the Hathaway-Wilson-Reichmann Shape-Fitting Function  

NASA Technical Reports Server (NTRS)

On the basis of 12-month moving averages (12-mma) of monthly mean sunspot number (R), sunspot cycle 24 had its minimum amplitude (Rm = 1.7) in December 2008. At 12 mo past minimum, R measured 8.3, and at 18 mo past minimum, it measured 16.4. Thus far, the maximum month-to-month rate of rise in 12-mma values of monthly mean sunspot number (AR(t) max) has been 1.7, having occurred at elapsed times past minimum amplitude (t) of 14 and 15 mo. Compared to other sunspot cycles of the modern era, cycle 24?s Rm and AR(t) max (as observed so far) are the smallest on record, suggesting that it likely will be a slow-rising, long-period sunspot cycle of below average maximum amplitude (RM). Supporting this view is the now observed relative strength of cycle 24?s geomagnetic minimum amplitude as measured using the 12-mma value of the aa-geomagnetic index (aam = 8.4), which also is the smallest on record, having occurred at t equals 8 and 9 mo. From the method of Ohl (the inferred preferential association between RM and aam), one predicts RM = 55 +/- 17 (the ?1 se prediction interval) for cycle 24. Furthermore, from the Waldmeier effect (the inferred preferential association between the ascent duration (ASC) and RM) one predicts an ASC longer than 48 mo for cycle 24; hence, maximum amplitude occurrence should be after December 2012. Application of the Hathaway-Wilson-Reichmann shape-fitting function, using an RM = 70 and ASC = 56 mo, is found to adequately fit the early sunspot number growth of cycle 24.

Wilson, Robert M.

2011-01-01

116

A Dynamic View of ATP-coupled Functioning Cycle of Hsp90 N-terminal Domain  

PubMed Central

Heat-shock protein 90 (Hsp90) is one of the most important chaperones involved in multiple cellular processes. The chaperoning function of Hsp90 is intimately coupled to the ATPase activity presented by its N-terminal domain. However, the molecular mechanism for the ATP-dependent working cycle of Hsp90 is still not fully understood. In this study, we use NMR techniques to investigate the structural characteristics and dynamic behaviors of Hsp90 N-terminal domain in its free and AMPPCP (ATP analogue) or ADP-bound states. We demonstrated that although AMPPCP and ADP bind to almost the same region of Hsp90, significantly different effects on the dynamics behaviors of the key structural elements were observed. AMPPCP binding favors the formation of the active homodimer of Hsp90 by enhancing the slow-motion featured conformational exchanges of those residues (A117–A141) within the lid segment (A111–G135) and around region, while ADP binding keeps Hsp90 staying at the inactive state by increasing the conformational rigidity of the lid segment and around region. Based on our findings, a dynamic working model for the ATP-dependent functioning cycle of Hsp90 was proposed. PMID:25867902

Zhang, Huaqun; Zhou, Chen; Chen, Wuyan; Xu, Yechun; Shi, Yanhong; Wen, Yi; Zhang, Naixia

2015-01-01

117

Driving Parts of Krebs Cycle in Reverse through Mineral Photochemistry Xiang V. Zhang and Scot T. Martin*  

E-print Network

M sodium oxaloacetate and 8 mM Na2S. The pH was adjusted to 6.3 by the addition of sulfuric acid, causing advanced self-replicating biotic systems.2 The prebiotic reductive tricarboxylic acid (rTCA) cycle (also called the reverse Krebs cycle or the reductive citric acid cycle; Figure 1) has received much attention

118

Experience utilizing a 3.7 MeV tandem cascade accelerator (TCA) for PET radioisotope production  

SciTech Connect

A 3.7 MeV TCA was installed at Washington University in the Spring of 1993 for evaluation as a PET isotope production accelerator. The accelerator was installed in a specially designed suite consisting of the accelerator room, a {open_quotes}hot lab{close_quotes} and a {open_quotes}cold lab{close_quotes}. The accelerator has been utilized routinely for PET isotope production since it`s installation. Although the major radionuclide produced utilizing the TCA is oxygen-15, techniques for the production of fluorine-18 and nitrogen-13 have been developed. The novel techniques used to produce usable quantities of these latter two isotopes will be discussed.

Welch, M.J.; Gaehle, G.; Dence, C.S. [Washington Univ. Medical School, St. Louis, MO (United States)] [and others

1994-12-31

119

Thermally Activated Persulfate Oxidation of Trichloroethylene (TCE) and 1,1,1Trichloroethane (TCA) in Aqueous Systems and Soil Slurries  

Microsoft Academic Search

Under thermally activated conditions (i.e., temperature of 40?99°C), there is considerable evidence that the persulfate anion () can be converted to a powerful oxidant known as the sulfate free radical (), which could be used in situ to destroy groundwater contaminants. In this laboratory study only limited trichloroethylene (TCE) degradation and no 1,1,1-trichloroethane (TCA) degradation was observed at 20°C. However,

Chen Ju Liang; Clifford J. Bruell; Michael C. Marley; Kenneth L. Sperry

2003-01-01

120

Therapeutic effect of functional electrical stimulation-triggered gait training corresponding gait cycle for stroke.  

PubMed

The purpose of this study was to determine the therapeutic effects of functional electrical stimulation (FES) applied to the gluteus medius and tibialis anterior muscles during the gait cycle in individuals with hemiparetic stroke. Eighteen patients who had suffered a stroke were enrolled in this study. The participants were divided into either the gluteus medius and tibialis anterior (GM + TA) training group (n = 9) or the control group (n = 9). The GM + TA group received FES-triggered gait training to the gluteus medius (GM) in the stance phase and the tibialis anterior (TA) in the swing phase for 30 min, 5 session a week over a 6-week period, and control group who received only gait training without FES-triggered for the same duration of time. A foot-switch sensor was used to trigger the device in the stance (GM) and swing (TA) phases of the gait cycle reciprocally. This study measured three types of outcome measures, including spatiotemporal gait parameters, muscles activities, and balance function. After 6 weeks training, there was a significant improvement in gait velocity, cadence, stride length, and gait symmetry in the GM + TA training group compared to the control group. Dynamic balance function was significantly improved in the GM + TA training group compared to the control group. The mean changeable values of the GM was significantly greater strength in the GM + TA training group than the control group. These findings suggest that FES-triggered gait training of the GM in the stance phase and TA in the swing phase may improve the spatiotemporal parameters of gait in persons with hemiparetic stroke. PMID:24973142

Chung, Yijung; Kim, Jung-Hyun; Cha, Yuri; Hwang, Sujin

2014-07-01

121

[Dynamic changes in functional genes for nitrogen bioremediation of petroleum-contaminated soil cycle during].  

PubMed

Microorganisms in nitrogen cycle serve as an important part of the ecological function of soil. The aim of this research was to monitor the abundance of nitrogen-fixing, denitrifying and nitrifying bacteria during bioaugmentation of petroleum-contaminated soil using real-time polymerase chain reaction (real-time PCR) of nifH, narG and amoA genes which encode the key enzymes in nitrogen fixation, nitrification and ammoniation respectively. Three different kinds of soils, which are petroleum-contaminated soil, normal soil, and remediated soil, were monitored. It was shown that the amounts of functional microorganisms in petroleum-contaminated soil were far less than those in normal soil, while the amounts in remediated soil and normal soil were comparable. Results of this experiment demonstrate that nitrogen circular functional bacteria are inhibited in petroleum-contaminated soil and can be recovered through bioremediation. Furthermore, copies of the three functional genes as well as total petroleum hydrocarbons (TPH) for soils with six different treatments were monitored. Among all treatments, the one, into which both E. cloacae as an inoculant and wheat straw as an additive were added, obtained the maximum copies of 2.68 x 10(6), 1.71 x 10(6) and 8.54 x 10(4) per gram dry soil for nifH, narG and amoA genes respectively, companying with the highest degradation rate (48% in 40 days) of TPH. The recovery of functional genes and removal of TPH were better in soil inoculated with E cloacae and C echinulata collectively than soil inoculated with E cloacae only. All above results suggest that the nitrogen circular functional genes could be applied to monitor and assess the bioremediation of petroleum-contaminated soil. PMID:22946197

Wu, Bin-Bin; Lu, Dian-Nan; Liu, Zheng

2012-06-01

122

Anti-hepatoma cells function of luteolin through inducing apoptosis and cell cycle arrest.  

PubMed

The aim of this study is to explore the apoptotic induction and cell cycle arrest function of luteolin on the liver cancer cells and the related mechanism. The liver cancer cell line SMMC-7721, BEL-7402, and normal liver cells HL-7702 were treated with different concentrations of luteolin. Cell proliferation ability was tested. Morphological changes of the apoptotic cells were observed under inverted fluorescence microscope after Hoechst33342 staining. We investigated the effect of luteolin on cell cycling and apoptosis with flow cytometry. The mitochondrial membrane potential changes were analyzed after JC-1 staining. Caspases-3 and Bcl-2 family proteins expression were analyzed by real-time PCR. Cell proliferation of SMMC-7721 and BEL-7402 were inhibited by luteolin, and the inhibition was dose-time-dependent. Luteolin could arrest the cells at G1/S stage, reduce mitochondrial membrane potential, and induce higher apoptosis rate and the typical apoptotic morphological changes of the liver carcinoma cells. Q-RT-PCR results also showed that luteolin increased Bax and caspase-3 expression significantly and upregulated Bcl-2 expression in a dose-dependent manner in liver carcinoma cells. However, the normal liver cells HL-7702 was almost not affected by luteolin treatment. Luteolin can inhibit SMMC-7721 and BEL-7402 cell proliferation in a time- and dose-dependent manner. And the mechanism maybe through arresting cell cycle at phase G1/S, enhancing Bax level, reducing anti-apoptotic protein Bcl-2 level, resulting in activating caspase-3 enzyme and decrease of mitochondrial membrane potential, and finally leading to cell apoptosis. PMID:24287949

Ding, Shixiong; Hu, Airong; Hu, Yaoren; Ma, Jianbo; Weng, Pengjian; Dai, Jinhua

2014-04-01

123

Life cycle, migration and antigen presenting functions of spleen and lymph node dendritic cells: Limitations of the Langerhans cells paradigm  

Microsoft Academic Search

The phenotypic and functional studies carried out in recent years on dendritic cells (DC) purified from spleen and lymph nodes has revealed the existence of heterogeneous populations with distinct life cycles, migratory properties and antigen presenting functions. A major subdivision can be made between “tissue derived” DC that migrate to the lymph nodes from peripheral tissues, both in the steady

José A. Villadangos; William R. Heath

2005-01-01

124

Tumor cycling hypoxia induces chemoresistance in glioblastoma multiforme by upregulating the expression and function of ABCB1  

PubMed Central

Tumor cycling hypoxia is now a well-recognized phenomenon in animal and human solid tumors. However, how tumor cycling hypoxia impacts chemotherapy is unclear. In the present study, we explored the impact and the mechanism of cycling hypoxia on tumor microenvironment-mediated chemoresistance. Hoechst 33342 staining and hypoxia-inducible factor–1 (HIF-1) activation labeling together with immunofluorescence imaging and fluorescence-activated cell sorting were used to isolate hypoxic tumor subpopulations from human glioblastoma xenografts. ABCB1 expression, P-glycoprotein function, and chemosensitivity in tumor cells derived from human glioblastoma xenografts or in vitro cycling hypoxic stress-treated glioblastoma cells were determined using Western blot analysis, drug accumulation and efflux assays, and MTT assay, respectively. ABCB1 expression and P-glycoprotein function were upregulated under cycling hypoxia in glioblastoma cells concomitant with decreased responses to doxorubicin and BCNU. However, ABCB1 knockdown inhibited these effects. Moreover, immunofluorescence imaging and flow cytometric analysis for ABCB1, HIF-1 activation, and Hoechst 3342 in glioblastoma revealed highly localized ABCB1 expression predominantly in potentially cycling hypoxic areas with HIF-1 activation and blood perfusion in the solid tumor microenvironment. The cycling hypoxic tumor cells derived from glioblastoma xenografts exhibited higher ABCB1 expression, P-glycoprotein function, and chemoresistance, compared with chronic hypoxic and normoxic cells. Tumor-bearing mice that received YC-1, an HIF-1? inhibitor, exhibited suppressed tumor microenvironment-induced ABCB1 induction and enhanced survival rate in BCNU chemotherapy. Cycling hypoxia plays a vital role in tumor microenvironment-mediated chemoresistance through the HIF-1–dependent induction of ABCB1. HIF-1 blockade before and concurrent with chemotherapy could suppress cycling hypoxia-induced chemoresistance. PMID:22946104

Chou, Chii-Wen; Wang, Chi-Chung; Wu, Chung-Pu; Lin, Yu-Jung; Lee, Yu-Chun; Cheng, Ya-Wen; Hsieh, Chia-Hung

2012-01-01

125

Functional diversity of bacterioplankton in three North Florida freshwater lakes over an annual cycle.  

PubMed

The phylogenetic diversity of freshwater bacterioplankton is widely known; however, there is minimal information on the functional diversity of the bacterial communities in these systems. Understanding the functional diversity of freshwater bacterial communities is important because heterotrophic bacteria can be impacted by anthropogenic perturbation, which in turn can alter biogeochemical cycling. The objective of this study was to use Biolog EcoPlates to acquire spatial and temporal community-level physiological profiles (CLPPs) for three freshwater lakes of different trophic levels and to assess the phylogenetic affiliation of the bacteria responsible for utilizing the various carbon guilds within them by denaturing gradient gel electrophoresis (DGGE). CLPP results showed that bacterial communities utilized the carbon guilds similarly between sites within the three lakes. However, when the metabolic profile of each lake was compared, Lake Bradford and Moore Lake were more similar to one another than to Lake Munson, the eutrophic lake. Additionally, although the bacteria that utilized the five carbon guilds included representatives from the classes ?-, ?-, ?-Proteobacteria, Flavobacteria and Sphingobacteria, Lake Munson had the largest number of Flavobacteria and ?-Proteobacteria in comparison to Moore Lake and Lake Bradford. Overall, Biolog analysis was useful in identifying differences in the functional diversity of bacterial communities between lakes of different trophic statuses and can be used as a tool to assess ecosystem health. PMID:24141941

Dickerson, Tamar L; Williams, Henry N

2014-01-01

126

The N cycle in Earth subsurface. Reactivity of functional genes to anthropogenic CO2 injections.  

NASA Astrophysics Data System (ADS)

The Nitrogen cycle has been widely studied in surface ecosystems, due to the importance of this nutrient for the organisms' development, and to the impact in the environment of most of the N forms, many of them being considered pollutants. However, little is known about the importance of the N-related metabolisms in subsurface systems now recognized to host diverse and active microbial life. In this study, we have periodically sampled the subsurface aquifers of the Icelandic pilot site for CO2 storage associated with the geothermal plant of Hellisheidi (operated by Reykjavik Energy; http://www.or.is/en/projects/carbfix). With the aim of understanding the dynamics of N-cycle in the subsurface, and its reactivity to CO2 injections, we quantified through qPCR the functional genes amoA (archaea), amoA (bacteria), nirK, nirS, nosZ, nifH, and the 16SrRNA genes of the anammox, total archaea and total bacteria. The 16SrRNA gene quantification provided values of around 107 gene copies/l at non injection periods. CO2 injection caused first a slight decrease probably due to pH decrease or toxicity by oxygen contamination during the injections. Two months after injection, the copy numbers increased up to 109 gene copies/l, and slowly returned to pre-injection values. The archaeal 16S rDNA copy numbers showed a similar reaction, with higher toxicity effects, and a lower increase afterwards. Due to the high reactivity of the microbial populations to CO2 injections, all the N cycle quantifications were related to the total 16S rDNA copies for normalization. Nitrifying genes (amoA) were mainly represented by the ammonia oxidizing archaea, and were apparently not affected by CO2 injections. Anammox bacteria were present in a very low percentage, and the obtained copy numbers tended to decrease after the injection. These results were surprising due to the autotrophic character of ammonia oxidizers, but could be explained by a competitive exclusion. On the contrary, N-fixation (nifH) was stimulated by the injections, doubling their relative abundance in relation to bacteria 16S rDNA copy numbers, supplying the N requirements of new biomass formed by autotrophic CO2 fixation. Finally, denitrifying bacteria (nirK, nirS and nosZ) showed a higher seasonal variation, but were positively stimulated by the CO2 injections. This process can be autotrophic in some species, using directly the injected CO2 as C source. Altogether the results suggest a high response of the N cycle to the CO2 injections, and its potential contribution to the formation of new biomass and C fixation. We provide evidences for the importance of the N cycle on the subsurface and its reactivity to CO2 injections, being therefore important the consideration of this cycle in CO2 storage modelling.

Trias, Rosalia; Gérard, Emmanuelle; Le Campion, Paul; Gíslason, Sigurður R.; Aradóttir, Edda S.; Alfreðsson, Helgui A.; Mesfin, Kiflom G.; Snæbjörnsdóttir, Sandra Ó.; Ménez, Bénédicte

2014-05-01

127

Analysis of tricarboxylic acid-cycle metabolism of hepatoma cells by comparison of 14CO2 ratios.  

PubMed Central

The CO2-ratios method is applied to the analysis of abnormalities of TCA (tricarboxylic acid)-cycle metabolism in AS-30D rat ascites-hepatoma cells. This method utilizes steady-state 14CO2-production rates from pairs of tracers of the same compound to evaluate TCA-cycle flux patterns. Equations are presented that quantitatively convert CO2 ratios into estimates of probability of flux through TCA-cycle-related pathways. Results of this study indicated that the ratio of 14CO2 produced from [1,4-14C]succinate to 14CO2 produced from [2,3-14C]succinate was increased by the addition of glutamine (5 mM) to the medium. An increase in the succinate CO2 ratio is quantitatively related to an increased flux of unlabelled carbon into the TCA-cycle-intermediate pools. Analysis of 14C distribution in [14C]citrate derived from [2,3-14C]succinate indicated that flux from the TCA cycle to the acetyl-CoA-derived carbons of citrate was insignificant. Thus the increased succinate CO2 ratio observed in the presence of glutamine could only result from an increased flux of carbon into the span of the TCA cycle from citrate to oxaloacetate. This result is consistent with increased flux of glutamine to alpha-oxoglutarate in the incubation medium containing exogenous glutamine. Comparison of the pyruvate CO2 ratio, steady-state 14CO2 production from [2-14C]pyruvate versus [3-14C]pyruvate, with the succinate 14CO2 ratio detected flux of pyruvate to C4 TCA-cycle intermediates in the medium containing glutamine. This result was consistent with the observation that [14C]aspartate derived from [2-14C]pyruvate was labelled in C-2 and C-3. 14C analysis also produced evidence for flux of TCA-cycle carbon to alanine. This study demonstrates that the CO2-ratios method is applicable in the analysis of the metabolic properties of AS-30D cells. This methodology has verified that the atypical TCA-cycle metabolism previously described for AS-30D-cell mitochondria occurs in intact AS-30D rat hepatoma cells. PMID:3120698

Kelleher, J K; Bryan, B M; Mallet, R T; Holleran, A L; Murphy, A N; Fiskum, G

1987-01-01

128

Physiological and pathophysiological functions of cell cycle proteins in post-mitotic neurons: implications for Alzheimer's disease.  

PubMed

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder for which no effective treatment is available. Increased insight into the disease mechanism in early stages of pathology is required for the development of a successful therapy. Over the years, numerous studies have shown that cell cycle proteins are expressed in neurons of AD patients. Traditionally, neurons are considered to be post-mitotic, which means that they permanently retract from the cell cycle. The expression of cell cycle proteins in adult neurons of AD patients has therefore been suggested to promote or even instigate pathomechanisms underlying AD. Interestingly, expression of cell cycle proteins is detected in post-mitotic neurons of healthy controls as well, albeit to a lesser extent than in AD patients. This indicates that cell cycle proteins may serve important physiological functions in differentiated neurons. Here, we provide an overview of studies that support a role of cell cycle proteins in DNA repair and neuroplasticity in post-mitotic neurons. Aberrant control of these processes could, in turn, contribute to cell cycle-mediated neurodegeneration. The balance between regenerative and degenerative effects of cell cycle proteins in post-mitotic neurons might change throughout the different stages of AD. In the early stages of AD pathology, cell cycle protein expression may primarily occur to aid in the repair of sublethal double-strand breaks in DNA. With the accumulation of pathology, cell cycle-mediated neuroplasticity and neurodegeneration may become more predominant. Understanding the physiological and pathophysiological role of cell cycle proteins in AD could give us more insight into the neurodegenerative process in AD. PMID:25618528

van Leeuwen, Lucie A G; Hoozemans, Jeroen J M

2015-04-01

129

Development of long-life-cycle tablet ceramic adsorbent for geosmin removal from water solution  

NASA Astrophysics Data System (ADS)

In this study, the tablet ceramic adsorbent (TCA), a silica/iron(III) oxide composite material, has been developed for geosmin (GSM) removal from the water solution. The physicochemical characteristics of TCA were examined with XRD, SEM, EDX and BET analyses. The sorption characteristics of GSM on TCA were investigated in a batch system. Attempts have been made to understand the adsorption kinetics, the effect of initial GSM concentration, solution pH, and reaction time. The batch experiments equilibrium data were well fitted to the Lagergren kinetic equation, which indicate the first-order nature adsorption. Over 82% of the GSM was removed by the TCA within 600 min at an initial concentration of 200 ng/L with 20 g/L of TCA dose. The batch and regeneration study indicated that the TCA is a cost-effective GSM adsorbent with sufficient mechanical strength to retain its physical integrity after long-time adsorption, and high regeneration performance for long-life-cycle application. Almost no second contamination (toxic sludge or leached iron) was observed after adsorption, and the gas resultant of thermal regeneration is harmless to atmospheric environment.

Chen, Rongzhi; Xue, Qiang; Zhang, Zhenya; Sugiura, Norio; Yang, Yingnan; Li, Miao; Chen, Nan; Ying, Zhao; Lei, Zhongfang

2011-01-01

130

Applying fuzzy logic to control cycling movement induced by functional electrical stimulation  

Microsoft Academic Search

This study examines the design of a rational stimulation pattern for electrical stimulation and a robust closed-loop control scheme to improve cycling system efficacy for subjects with paraplegia. The stimulation patterns were designed by analyzing gravitation potential needed for the cycling movement of the lower limbs against a frictionless cycling ergometer and the response delay of electrically stimulated muscles. To

Jia-Jin J. Chen; Nan-Ying Yu; Ding-Gau Huang; Bao-Ting Ann; Gwo-Ching Chang

1997-01-01

131

Progesterone mediates brain functional connectivity changes during the menstrual cycle-a pilot resting state MRI study.  

PubMed

The growing interest in intrinsic brain organization has sparked various innovative approaches to generating comprehensive connectivity-based maps of the human brain. Prior reports point to a sexual dimorphism of the structural and functional human connectome. However, it is uncertain whether subtle changes in sex hormones, as occur during the monthly menstrual cycle, substantially impact the functional architecture of the female brain. Here, we performed eigenvector centrality (EC) mapping in 32 longitudinal resting state fMRI scans of a single healthy subject without oral contraceptive use, across four menstrual cycles, and assessed estrogen and progesterone levels. To investigate associations between cycle-dependent hormones and brain connectivity, we performed correlation analyses between the EC maps and the respective hormone levels. On the whole brain level, we found a significant positive correlation between progesterone and EC in the bilateral dorsolateral prefrontal cortex (DLPFC) and bilateral sensorimotor cortex. In a secondary region-of-interest analysis, we detected a progesterone-modulated increase in functional connectivity of both bilateral DLPFC and bilateral sensorimotor cortex with the hippocampus. Our results suggest that the menstrual cycle substantially impacts intrinsic functional connectivity, particularly in brain areas associated with contextual memory-regulation, such as the hippocampus. These findings are the first to link the subtle hormonal fluctuations that occur during the menstrual cycle, to significant changes in regional functional connectivity in the hippocampus in a longitudinal design, given the limitation of data acquisition in a single subject. Our study demonstrates the feasibility of such a longitudinal Resting-state functional Magnetic Resonance Imaging (rs-fMRI) design and illustrates a means of creating a personalized map of the human brain by integrating potential mediators of brain states, such as menstrual cycle phase. PMID:25755630

Arélin, Katrin; Mueller, Karsten; Barth, Claudia; Rekkas, Paraskevi V; Kratzsch, Jürgen; Burmann, Inga; Villringer, Arno; Sacher, Julia

2015-01-01

132

Progesterone mediates brain functional connectivity changes during the menstrual cycle—a pilot resting state MRI study  

PubMed Central

The growing interest in intrinsic brain organization has sparked various innovative approaches to generating comprehensive connectivity-based maps of the human brain. Prior reports point to a sexual dimorphism of the structural and functional human connectome. However, it is uncertain whether subtle changes in sex hormones, as occur during the monthly menstrual cycle, substantially impact the functional architecture of the female brain. Here, we performed eigenvector centrality (EC) mapping in 32 longitudinal resting state fMRI scans of a single healthy subject without oral contraceptive use, across four menstrual cycles, and assessed estrogen and progesterone levels. To investigate associations between cycle-dependent hormones and brain connectivity, we performed correlation analyses between the EC maps and the respective hormone levels. On the whole brain level, we found a significant positive correlation between progesterone and EC in the bilateral dorsolateral prefrontal cortex (DLPFC) and bilateral sensorimotor cortex. In a secondary region-of-interest analysis, we detected a progesterone-modulated increase in functional connectivity of both bilateral DLPFC and bilateral sensorimotor cortex with the hippocampus. Our results suggest that the menstrual cycle substantially impacts intrinsic functional connectivity, particularly in brain areas associated with contextual memory-regulation, such as the hippocampus. These findings are the first to link the subtle hormonal fluctuations that occur during the menstrual cycle, to significant changes in regional functional connectivity in the hippocampus in a longitudinal design, given the limitation of data acquisition in a single subject. Our study demonstrates the feasibility of such a longitudinal Resting-state functional Magnetic Resonance Imaging (rs-fMRI) design and illustrates a means of creating a personalized map of the human brain by integrating potential mediators of brain states, such as menstrual cycle phase. PMID:25755630

Arélin, Katrin; Mueller, Karsten; Barth, Claudia; Rekkas, Paraskevi V.; Kratzsch, Jürgen; Burmann, Inga; Villringer, Arno; Sacher, Julia

2015-01-01

133

The iterated Carmichael l-function and the number of cycles of the power generator  

NASA Astrophysics Data System (ADS)

Iteration of the modular l-th power function f(x) = x^l (mod n) provides a common pseudorandom number generator (known as the Blum-Blum-Shub generator when l=2). The period of this pseudorandom number generator is closely related to \\lambda(\\lambda(n)), where \\lambda(n) denotes Carmichael's function, namely the maximal multiplicative order of any integer modulo n. In this paper, we show that for almost all n, the size of \\lambda(\\lambda(n)) is n/exp((1+o(1))(log log n)^2 log log log n). We conjecture an analogous formula for the k-th iterate of \\lambda. We deduce that for almost all n, the psuedorandom number generator described above has at least exp((1+o(1))(log log n)^2 log log log n) disjoint cycles. In addition, we show that this expression is accurate for almost all n under the assumption of the Generalized Riemann Hypothesis for Kummerian fields. We also consider the number of iterations of \\lambda it takes to reduce an integer n to 1, proving that this number is less than (1+o(1))(log log n)/log 2 infinitely often and speculating that log log n is the true order of magnitude almost always.

Martin, Greg; Pomerance, Carl

134

Parametric Flutter Analysis of the TCA Configuration and Recommendation for FFM Design and Scaling  

NASA Technical Reports Server (NTRS)

The current HSR Aeroelasticity plan to design, build, and test a full span, free flying transonic flutter model in the TDT has many technical obstacles that must be overcome for a successful program. One technical obstacle is the determination of a suitable configuration and point in the sky to use in setting the scaling point for the ASE models program. Determining this configuration and point in the sky requires balancing several conflicting requirements, including model buildability, tunnel test safety, and the ability of the model to represent the flutter mechanisms of interest. As will be discussed in detail in subsequent sections, the current TCA design exhibits several flutter mechanisms of interest. It has been decided that the ASE models program will focus on the low frequency symmetric flutter mechanism, and will make no attempt to investigate high frequency flutter mechanisms. There are several reasons for this choice. First, it is believed that the high frequency flutter mechanisms are similar in nature to classical wing bending/torsion flutter, and therefore there is more confidence that this mechanism can be predicted using current techniques. The low frequency mode, on the other hand, is a highly coupled mechanism involving wing, body, tail, and engine motion which may be very difficult to predict. Second, the high frequency flutter modes result in very small weight penalties (several hundred pounds), while suppression of the low frequency mechanism inside the flight envelope causes thousands of pounds to be added to the structure. In order to successfully test the low frequency flutter mode of interest, a suitable starting configuration and point in the sky must be identified. The configuration and point in the sky must result in a wind tunnel model that (1) represents the low-frequency wing/body/engine/empennage flutter mechanisms that are unique to HSCT configurations, (2) flutters at an acceptably low frequency in the tunnel, (3) flutters at an acceptably low dynamic pressure in the tunnel, (4) allows sufficient weight for model buildability without inordinately high cost, and (5) has significant separation between the target flutter mechanism and other, potentially catastrophic, flutter mechanisms.

Baker, Myles; Lenkey, Peter

1997-01-01

135

Ingestion of sodium plus water improves cardiovascular function and performance during dehydrating cycling in the heat.  

PubMed

We studied if salt and water ingestion alleviates the physiological strain caused by dehydrating exercise in the heat. Ten trained male cyclists (VO2max?: 60 ± 7 mL/kg/min) completed three randomized trials in a hot-dry environment (33 °C, 30% rh, 2.5 m/s airflow). Ninety minutes before the exercise, participants ingested 10 mL of water/kg body mass either alone (CON trial) or with salt to result in concentrations of 82 or 164 mM Na(+) (ModNa(+) or HighNa(+) trial, respectively). Then, participants cycled at 63% of VO2 m ? a x for 120 min immediately followed by a time-trial. After 120 min of exercise, the reduction in plasma volume was lessened with ModNa(+) and HighNa(+) trials (-11.9 ± 2.1 and -9.8 ± 4.2%) in comparison with CON (-16.4 ± 3.2%; P < 0.05). However, heat accumulation or dissipation (forearm skin blood flow and sweat rate) were not improved by salt ingestion. In contrast, both salt trials maintained cardiac output (? 1.3 ± 1.4 L/min; P < 0.05) and stroke volume (? 10 ± 11 mL/beat; P < 0.05) above CON after 120 min of exercise. Furthermore, the salt trials equally improved time-trial performance by 7.4% above CON (? 289 ± 42 vs 269 ± 50 W, respectively; P < 0.05). Our data suggest that pre-exercise ingestion of salt plus water maintains higher plasma volume during dehydrating exercise in the heat without thermoregulatory effects. However, it maintains cardiovascular function and improves cycling performance. PMID:23253191

Hamouti, N; Fernández-Elías, V E; Ortega, J F; Mora-Rodriguez, R

2014-06-01

136

Potential Abiotic Functions of Root Exudates in Rhizosphere Cycling of Soil Organic Matter  

NASA Astrophysics Data System (ADS)

Carbon cycling in the rhizosphere is a nexus of biophysical interactions between plant roots, microorganisms and the soil organo-mineral matrix. Plant roots are the primary source of C in mineral horizons and can significantly accelerate the rate of soil organic matter mineralization in rhizosphere soils. While a portion of this acceleration results from stimulation of microbial enzymatic capacities (the 'priming effect') - abiotic responses also play a significant role in rhizosphere cycling of soil organic matter (SOM). For example, exudate-stimulated mobilization and dissolution of metal species may release previously complexed SOM, or could affect Fe mobility via redox changes associated with microbially-driven O2 depletion. We have investigated the abiotic response of rhizosphere microenvironments, using additions of several 13C-enriched low molecular weight (LMW) root exudates and 13C-plant detritus to controlled microcosms. We hypothesized that certain abiotic effects are triggered by specific exudate compounds and that the magnitude of the effect depends on the soil physiochemical properties. Using a combination of microsensor measurements, solid-phase extractions, X-ray and IR spectroscopy, we measured how root exudates differ in their potential to create reducing microenvironments, alter metal chemisty and mineralogy, and influence the availability of SOM in the rhizosphere. High resolution X-ray microscopy (STXM) and secondary ion mass spectrometry (NanoSIMS) analyses illustrate the physical fate of the added isotope tracers in both pore water and on mineral surfaces. Our results suggest that certain root exudates facilitate abiotic reactions that increase the pool of bioavailable SOM and stimulate its microbial decomposition in the rhizosphere. In particular, the contrasting ecological functions of LMW organic acids and simple sugars in facilitating SOM breakdown in the rhizosphere will be discussed.

Pett-Ridge, J.; Keiluweit, M.; Bougoure, J.; Kleber, M.; Nico, P. S.

2012-12-01

137

Spatial Distribution of Cellular Function: The Partitioning of Proteins between Mitochondria and the Nucleus in MCF7 Breast Cancer Cells  

PubMed Central

Concurrent proteomics analysis of the nuclei and mitochondria of MCF7 breast cancer cells identified 985 proteins (40% of all detected proteins) present in both organelles. Numerous proteins from all five complexes involved in oxidative phosphorylation (e.g., NDUFA5, NDUFB10, NDUFS1, NDUF2, SDHA, UQRB, UQRC2, UQCRH, COX5A, COX5B, MT-CO2, ATP5A1, ATP5B, ATP5H, etc.), from the TCA-cycle (DLST, IDH2, IDH3A, OGDH, SUCLAG2, etc.), and from glycolysis (ALDOA, ENO1, FBP1, GPI, PGK1, TALDO1, etc.) were distributed to both the nucleus and mitochondria. In contrast, proteins involved in nuclear/mitochondrial RNA processing/translation and Ras/Rab signaling showed different partitioning patterns. The identity of the OxPhos, TCA-cycle, and glycolysis proteins distributed to both the nucleus and mitochondria provides evidence for spatio-functional integration of these processes over the two different subcellular organelles. We suggest that there are unrecognized aspects of functional coordination between the nucleus and mitochondria, that integration of core functional processes via wide subcellular distribution of constituent proteins is a common characteristic of cells, and that subcellular spatial integration of function may be a vital aspect of cancer. PMID:23051583

Qattan, Amal T.; Radulovic, Marko; Crawford, Mark; Godovac-Zimmermann, Jasminka

2014-01-01

138

Seasonal redistribution of immune function in a migrant shorebird: annual-cycle effects override adjustments to thermal regime.  

PubMed

Throughout the annual cycle, demands on competing physiological systems change, and animals must allocate resources to maximize fitness. Immune function is one such system and is important for survival. Yet detailed empirical data tracking immune function over the entire annual cycle are lacking for most wild animals. We measured constitutive immune indices once a month for a year on captive red knots (Calidris canutus). We also examined temperature as an environmental contributor to immune variation by manipulating ambient temperature to vary energy expenditure. To identify relationships among immune indices, we performed principal-component analysis. We found significant repeatability in immune indices over the annual cycle and covariation of immune indices within and among individuals. This covariation suggests immune strategies as individual traits among individuals and the use of different immune strategies during different annual-cycle stages within individuals. Over the annual cycle, both higher-cost phagocyte-based immunity and lower-cost lymphocyte-based immunity were high during mass change, but there was a clear shift toward lower-cost lymphocyte-based immunity during peak molt. Experimental manipulation of temperature had little effect on annual variation in immune function. This suggests that other environmental factors, such as food availability and disease, should also be examined in the future. PMID:18999941

Buehler, Deborah M; Piersma, Theunis; Matson, Kevin; Tieleman, B Irene

2008-12-01

139

Functional citric acid cycle in an arcA mutant of Escherichia coli during growth with nitrate under anoxic conditions.  

PubMed

The operation of the citric acid cycle of Escherichia coli during nitrate respiration (anoxic conditions) was studied by measuring end products and enzyme activities. Excretion of products other than CO2, such as acetate or ethanol, was taken as an indication for a non-functional cycle. From glycerol, approximately 0.3 mol acetate was produced; the residual portion was completely oxidized, indicating the presence of a partially active citric acid cycle. In an arcA mutant devoid of the transcriptional regulator ArcA, glycerol was completely oxidized with nitrate as an electron acceptor, demonstrating derepression and function of the complete pathway. Glucose, on the other hand, was excreted mostly as acetate by the wild-type and by the arcA mutant. During growth on glucose, but not on glycerol, activities of succinate dehydrogenase and of 2-oxoglutarate dehydrogenase were missing nearly completely. Thus, the previously described strong repression of the citric acid cycle during nitrate respiration occurs only during growth on glucose and is the effect of anaerobic and, more important, of glucose repression. In Pseudomonas fluorescens (but not Pseudomonas stutzeri), a similar decrease of citric acid cycle function during anaerobic growth with nitrate was found, indicating a broad distribution of this regulatory principle. PMID:9639597

Prohl, C; Wackwitz, B; Vlad, D; Unden, G

1998-07-01

140

Subcellular location and photodynamic therapeutic effect of chlorin e6 in the human tongue squamous cell cancer Tca8113 cell line  

PubMed Central

The present study aimed to investigate the distribution and photodynamic therapeutic effect of chlorin e6 (Ce6) in the human tongue squamous cell carcinoma Tca8113 cell line in vitro. The distribution of Ce6 in the Tca8113 cells was observed in situ combined with mitochondrial and lysosomal fluorescent probes. Next, 630-nm semiconductor laser irradiation was performed. The MTS colorimetric method was used to determine cell survival. Annexin V fluorescein isothiocyanate/propidium iodide (PI) double staining was used to detect early apoptosis following photodynamic therapy (PDT). The flow cytometer was used to analyze the DNA content subsequent to PI-staining. It was observed that Ce6 could combine with the cellular membrane following 30 min of incubation with the Tca8113 cells. As the length of incubation increased, Ce6 gradually entered the cells in a particular distribution and reached saturation by 3 h. Co-localization analysis demonstrated that Ce6 was more likely to be present in the mitochondria than in the lysosomes. The cells incubated with 5 ?g/ml Ce6 for 24 h exhibited a low toxicity of 5%, however, following light irradiation, Ce6-PDT was able to kill the Tca8113 cells in vitro. The cell toxicity was positively correlated with Ce6 concentration and light dose, therefore, the effect of Ce6 was concentration/dose-dependent (P<0.01). The lower Ce6 concentrations and light doses could significantly induce apoptosis in the Tca8113 cells, while higher doses increased necrosis/percentage of dead cells. In summary, Ce6 saturated the Tca8113 cells following 3 h of incubation. Furthermore, Ce6-PDT effectively killed the cultured Tca8113 cells in vitro at a safe concentration. At a low concentration and light dose, Ce6 is more likely to induce cell apoptosis via the mitochondria than the lysosomes. PMID:25621023

LUO, WEI; LIU, RONG-SEN; ZHU, JIAN-GUO; LI, YING-CHAO; LIU, HONG-CHEN

2015-01-01

141

Effects of Functional Electric Stimulation Cycle Ergometry Training on Lower Limb Musculature in Acute Sci Individuals  

PubMed Central

The purpose of this study was to compare three different intervals for a between sets rest period during a common isokinetic knee extension strength-testing protocol of twenty older Brazilian men (66.30 ± 3.92 yrs). The volunteers underwent unilateral knee extension (Biodex System 3) testing to determine their individual isokinetic peak torque at 60, 90, and 120° ·s-1. The contraction speeds and the rest periods between sets (30, 60 and 90 s) were randomly performed in three different days with a minimum rest period of 48 hours. Significant differences between and within sets were analyzed using a One Way Analysis of Variance (ANOVA) with repeated measures. Although, at angular velocity of 60°·s-1 produced a higher peak torque, there were no significant differences in peak torque among any of the rest periods. Likewise, there were no significant differences between mean peak torque among all resting periods (30, 60 and 90s) at angular velocities of 90 and 120°·s-1. The results showed that during a common isokinetic strength testing protocol a between set rest period of at least 30 s is sufficient for recovery before the next test set in older men. Key Points Muscle fiber cross sectional area (CSAf ) decreased 38% following spinal cord injury (SCI). Early intervention with functional electric stimulation cycle ergometry (FES-CE) prevented further loss of CSAf in SCI patients and increased power output. Muscle myosin heavy chain (MHC) and myonuclear density were unaffected by SCI or FES-CE PMID:24453530

Demchak, Timothy J.; Linderman, Jon K.; Mysiw, W. Jerry; Jackson, Rebecca; Suun, Jihong; Devor, Steven T.

2005-01-01

142

in vivo analysis of Drosophila deoxyribonucleoside kinase function in cell cycle, cell survival and anti-cancer drugs resistance  

E-print Network

1 in vivo analysis of Drosophila deoxyribonucleoside kinase function in cell cycle, cell survival Drosophila, deoxyribonucleoside kinase, dNK, antifolate resistance, apoptosis, proliferation, growth, dE2F1. Knecht and S.Carroll and the Bloomington Drosophila stock center for fly strains and antibodies

Boyer, Edmond

143

Altered contractile properties of the quadriceps muscle in people with spinal cord injury following functional electrical stimulated cycle training  

Microsoft Academic Search

Study design: A longitudinal training study. Objectives: To assess if contractile speed and fatigability of paralysed quadriceps muscles in individuals with spinal cord injury (SCI) can be altered by functional electrical stimulation leg cycle ergometry (FES-LCE) training. Settings: The Sint Maartenskliniek rehabilitation centre and the University of Nijmegen, Nijmegen, the Netherlands. Methods: Contractile properties of the quadriceps muscle were studied

H. L. Gerrits; A de Haan; A. J. Sargeant; A. J. Dallmeijer; M. T. E. Hopman

2000-01-01

144

A SET-domain-independent role of WRAD complex in cell-cycle regulatory function of mixed lineage leukemia  

PubMed Central

MLL, the trithorax ortholog, is a well-characterized histone 3 lysine 4 methyltransferase that is crucial for proper regulation of the Hox genes during embryonic development. Chromosomal translocations, disrupting the Mll gene, lead to aggressive leukemia with poor prognosis. However, the functions of MLL in cellular processes like cell-cycle regulation are not well studied. Here we show that the MLL has a regulatory role during multiple phases of the cell cycle. RNAi-mediated knockdown reveals that MLL regulates S-phase progression and, proper segregation and cytokinesis during M phase. Using deletions and mutations, we narrow the cell-cycle regulatory role to the C subunit of MLL. Our analysis reveals that the transactivation domain and not the SET domain is important for the S-phase function of MLL. Surprisingly, disruption of MLL–WRAD interaction is sufficient to disrupt proper mitotic progression. These mitotic functions of WRAD are independent of SET domain of MLL and, therefore, define a new role of WRAD in subset of MLL functions. Finally, we address the overlapping and unique roles of the different SET family members in the cell cycle. PMID:24880690

Ali, Aamir; Veeranki, Sailaja Naga; Tyagi, Shweta

2014-01-01

145

Computational functions in biochemical reaction networks.  

PubMed Central

In prior work we demonstrated the implementation of logic gates, sequential computers (universal Turing machines), and parallel computers by means of the kinetics of chemical reaction mechanisms. In the present article we develop this subject further by first investigating the computational properties of several enzymatic (single and multiple) reaction mechanisms: we show their steady states are analogous to either Boolean or fuzzy logic gates. Nearly perfect digital function is obtained only in the regime in which the enzymes are saturated with their substrates. With these enzymatic gates, we construct combinational chemical networks that execute a given truth-table. The dynamic range of a network's output is strongly affected by "input/output matching" conditions among the internal gate elements. We find a simple mechanism, similar to the interconversion of fructose-6-phosphate between its two bisphosphate forms (fructose-1,6-bisphosphate and fructose-2,6-bisphosphate), that functions analogously to an AND gate. When the simple model is supplanted with one in which the enzyme rate laws are derived from experimental data, the steady state of the mechanism functions as an asymmetric fuzzy aggregation operator with properties akin to a fuzzy AND gate. The qualitative behavior of the mechanism does not change when situated within a large model of glycolysis/gluconeogenesis and the TCA cycle. The mechanism, in this case, switches the pathway's mode from glycolysis to gluconeogenesis in response to chemical signals of low blood glucose (cAMP) and abundant fuel for the TCA cycle (acetyl coenzyme A). Images FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 7 FIGURE 10 FIGURE 12 FIGURE 13 FIGURE 14 FIGURE 15 FIGURE 16 PMID:7948674

Arkin, A; Ross, J

1994-01-01

146

Icotinib inhibits the invasion of Tca8113 cells via downregulation of nuclear factor ?B-mediated matrix metalloproteinase expression  

PubMed Central

Icotinib is an epidermal growth factor receptor tyrosine kinase inhibitor, which has been revealed to inhibit proliferation in tumor cells. However, the effect of icotinib on cancer cell metastasis remains to be explained. This study examines the effect of icotinib on the migration and invasion of squamous cells of tongue carcinoma (Tca8113 cells) in vitro. The results of the Boyden chamber invasion assay demonstrated that icotinib reduced cell invasion, suppressed the protein levels of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, and increased the expression of tissue inhibitor of metalloproteinase-1. In addition, icotinib was found to significantly decrease the protein levels of nuclear factor ?B (NF-?B) p65, which suggested that icotinib inhibits NF-?B activity. Furthermore, treatment with the NF-?B inhibitor, pyrrolidine dithiocarbamate, suppressed cell invasion and MMP-2 expression. These results suggested that icotinib inhibits the invasion of Tca8113 cells by downregulating MMP via the inactivation of the NF-?B signaling pathways. PMID:25120710

YANG, CAILING; YAN, JIANGUO; YUAN, GUOYAN; ZHANG, YINGHUA; LU, DERONG; REN, MINGXIN; CUI, WEIGANG

2014-01-01

147

Activated lymphocytes induce promoter activity of the TCA3 gene in mast cells following cell-to-cell contact.  

PubMed

Aggregates of mast cells and lymphocytes have been found in inflamed tissues suggesting that lymphocytes may have the ability to activate mast cells through cell-to-cell contact. To examine this hypothesis, murine mast cells were transfected with a T cell activation gene-3 (TCA3)-chloramphenicol acetyl transferase (CAT) construct, and these cells co-cultured with murine EL-4 (T), CH12.LX (B), WEHI-3 (myelomonocytic) or 3T3(fibroblast) cell lines. Co-culture of activated EL-4 or CH12.LX cells, but not WEHI-3 or 3T3 cells, with transfected mast cells induced a 5 to 7 fold increase in CAT expression which was dependent on the lymphocyte to mast cell ratio. Supernatants from activated EL-4 or CH12.LX cells did not induce CAT expression in transfected mast cells. These data demonstrate that activated lymphocytes have the ability to induce the promoter of the TCA3 gene in mast cells through a mechanism requiring cell-to-cell contact, and suggest the possibility that activated lymphocytes may effect other biologic processes in mast cells as well through such heterotypic activation. PMID:8629992

Oh, C K; Metcalfe, D D

1996-04-25

148

Functional genes to assess nitrogen cycling and aromatic hydrocarbon degradation: primers and processing matter  

PubMed Central

Targeting sequencing to genes involved in key environmental processes, i.e., ecofunctional genes, provides an opportunity to sample nature's gene guilds to greater depth and help link community structure to process-level outcomes. Vastly different approaches have been implemented for sequence processing and, ultimately, for taxonomic placement of these gene reads. The overall quality of next generation sequence analysis of functional genes is dependent on multiple steps and assumptions of unknown diversity. To illustrate current issues surrounding amplicon read processing we provide examples for three ecofunctional gene groups. A combination of in silico, environmental and cultured strain sequences was used to test new primers targeting the dioxin and dibenzofuran degrading genes dxnA1, dbfA1, and carAa. The majority of obtained environmental sequences were classified into novel sequence clusters, illustrating the discovery value of the approach. For the nitrite reductase step in denitrification, the well-known nirK primers exhibited deficiencies in reference database coverage, illustrating the need to refine primer-binding sites and/or to design multiple primers, while nirS primers exhibited bias against five phyla. Amino acid-based OTU clustering of these two N-cycle genes from soil samples yielded only 114 unique nirK and 45 unique nirS genus-level groupings, likely a reflection of constricted primer coverage. Finally, supervised and non-supervised OTU analysis methods were compared using the nifH gene of nitrogen fixation, with generally similar outcomes, but the clustering (non-supervised) method yielded higher diversity estimates and stronger site-based differences. High throughput amplicon sequencing can provide inexpensive and rapid access to nature's related sequences by circumventing the culturing barrier, but each unique gene requires individual considerations in terms of primer design and sequence processing and classification. PMID:24062736

Penton, C. Ryan; Johnson, Timothy A.; Quensen, John F.; Iwai, Shoko; Cole, James R.; Tiedje, James M.

2013-01-01

149

On form and function: does chromatin packing regulate the cell cycle?  

PubMed Central

The Systems Biology of Cell State Regulation Section is dedicated to considering how we can define a cellular state and how cells transition between states. One important decision that a cell makes is whether to cycle, that is, replicate DNA and generate daughter cells, or to exit the cell cycle in a reversible manner. The members of the Systems Biology of Cell State Regulation Editorial Board have an interest in the role of epigenetics and the commitment to a dividing or nondividing state. The ability of cells to transition between proliferating and nonproliferating states is essential for the proper formation of tissues. The ability to enter the cell cycle when needed is necessary for complex multicellular processes, such as healing injuries or mounting an immune response. Cells that fail to quiesce properly can contribute to the formation of tumors. In this perspective piece, we focus on research exploring the relationship between epigenetics and the cell cycle. PMID:24474443

Corney, David C.

2014-01-01

150

Stress and Eating Disorder Behavior in Anorexia Nervosa as a Function of Menstrual Cycle Status  

PubMed Central

Objective Fluctuations in ovarian hormones during the menstrual cycle and psychosocial stress contribute to eating disorder (ED) behavior. Methods Using ecological momentary assessment techniques, this study examined relationships between stress and binge eating, self-induced vomiting, and dietary restriction based on menstrual cycle status in anorexia nervosa (AN). 109 females with full and subthreshold AN (17–45 years old) recorded ED behavior and stress ratings over two weeks. Using hierarchical linear modeling, individuals with eumenorrhea and those with amenorrhea or oligomenorrhea were compared. Results Following episodes of meal skipping, momentary stress decreased in individuals with normal menstrual cycles and increased in those with irregular menstrual cycles. Discussion Results suggest that changes in stress severity in response to food restriction may differ based on ovarian hormonal status and may be a mechanism by which AN is maintained in individuals without menstrual disturbance. PMID:24222529

Jappe, Leah M.; Cao, Li; Crosby, Ross D.; Crow, Scott J.; Peterson, Carol B.; Le Grange, Daniel; Engel, Scott G.; Wonderlich, Stephen A.

2013-01-01

151

A Spring-Loaded State of NusG in Its Functional Cycle Is Suggested by X-ray Crystallography and Supported by Site-Directed Mutants  

E-print Network

A Spring-Loaded State of NusG in Its Functional Cycle Is Suggested by X-ray Crystallography NusG proteins contain a variable insertion sequence of 70 residues in the central region of the molecule and propose a spring-loaded state in the functional cycle of NusG. The importance of the ball

152

Predicting VO2max in College-Aged Participants Using Cycle Ergometry and Perceived Functional Ability  

Microsoft Academic Search

The purpose of this study was to develop a multiple linear regression model to predict treadmill VO2max scores using both exercise and non-exercise data. One hundred five college-aged participants (53 male, 52 female) successfully completed a submaximal cycle ergometer test and a maximal graded exercise test on a motorized treadmill. The submaximal cycle protocol required participants to achieve a steady-state

David E. Nielson; James D. George; Pat R. Vehrs; Ron L. Hager; Carrie V. Webb

2010-01-01

153

The anti-apoptosis function of Bcl-2 can be genetically separated from its inhibitory effect on cell cycle entry.  

PubMed Central

The Bcl-2 family of proteins regulate apoptosis, some antagonizing cell death and others facilitating it. It has recently been demonstrated that Bcl-2 not only inhibits apoptosis but also restrains cell cycle entry. We show here that these two functions can be genetically dissociated. Mutation of a tyrosine residue within the conserved N-terminal BH4 region had no effect on the ability of Bcl-2 or its closest homologs to enhance cell survival and did not prevent heterodimerization with death-enhancing family members Bax, Bak, Bad and Bik. Neither did this mutation override the growth-inhibitory effect of p53. However, on stimulation with cytokine or serum, starved quiescent cells expressing the mutant proteins re-entered the cell cycle much faster than those expressing comparable levels of wild-type proteins. When wild-type and Y28 mutant Bcl-2 were co-expressed, the mutant was dominant. Although R-Ras p23 has been reported to bind to Bcl-2, no interaction was detectable in transfected cells and R-Ras p23 did not interfere with the ability of Bcl-2 to inhibit apoptosis or cell cycle entry. These observations provide evidence that the anti-apoptotic function of Bcl-2 is mechanistically distinct from its inhibitory influence on cell cycle entry. PMID:9303307

Huang, D C; O'Reilly, L A; Strasser, A; Cory, S

1997-01-01

154

Anaplerotic Triheptanoin Diet Enhances Mitochondrial Substrate Use to Remodel the Metabolome and Improve Lifespan, Motor Function, and Sociability in MeCP2-Null Mice  

PubMed Central

Rett syndrome (RTT) is an autism spectrum disorder (ASD) caused by mutations in the X-linked MECP2 gene that encodes methyl-CpG binding protein 2 (MeCP2). Symptoms range in severity and include psychomotor disabilities, seizures, ataxia, and intellectual disability. Symptom onset is between 6-18 months of age, a critical period of brain development that is highly energy-dependent. Notably, patients with RTT have evidence of mitochondrial dysfunction, as well as abnormal levels of the adipokines leptin and adiponectin, suggesting overall metabolic imbalance. We hypothesized that one contributor to RTT symptoms is energy deficiency due to defective nutrient substrate utilization by the TCA cycle. This energy deficit would lead to a metabolic imbalance, but would be treatable by providing anaplerotic substrates to the TCA cycle to enhance energy production. We show that dietary therapy with triheptanoin significantly increased longevity and improved motor function and social interaction in male mice hemizygous for Mecp2 knockout. Anaplerotic therapy in Mecp2 knockout mice also improved indicators of impaired substrate utilization, decreased adiposity, increased glucose tolerance and insulin sensitivity, decreased serum leptin and insulin, and improved mitochondrial morphology in skeletal muscle. Untargeted metabolomics of liver and skeletal muscle revealed increases in levels of TCA cycle intermediates with triheptanoin diet, as well as normalizations of glucose and fatty acid biochemical pathways consistent with the improved metabolic phenotype in Mecp2 knockout mice on triheptanoin. These results suggest that an approach using dietary supplementation with anaplerotic substrate is effective in improving symptoms and metabolic health in RTT. PMID:25299635

Li, Qun; Degano, Alicia L.; Penati, Judith; Zhuo, Justin; Roe, Charles R.; Ronnett, Gabriele V.

2014-01-01

155

Stabilization of mitochondrial and microsomal function by polysaccharide of Ulva lactuca on D-Galactosamine induced hepatitis in rats.  

PubMed

In this study we used liver mitochondrial and microsomal fraction from rats pretreated with seaweed Ulva lactuca polysaccharide extract (ULP - 200mg/kg body weight, daily for 21 days, oral gavage) on D-Galactosamine (500mg/kg body weight, intraperitoneally) challenge. Effectiveness of ULP was determined based on functional status of trichloro acetic acid (TCA), urea cycle, and microsomal enzymes. The composition of sulfate polysaccharide content such as total sugars, sulfate and uronic acid were examined. In addition the fine ultra structural changes were examined using electron microscopy (EM). We observed significant (p<0.001) mitochondrial and microsomal abnormalities during liver damage by D-Galactosamine, consequently altering enzymes of energy metabolism. Electron microscopy of D-Galactosamine intoxicated rat liver tissue revealed the swelling and loss of mitochondrial cristae. Conversely the rats pretreated with ULP against D-Galactosamine challenge prevented (p<0.05) the significant abnormality of TCA, microsomal enzymes and severity of mitochondria as observed in EM study in rats injected with D-Galactosamine alone. However no effective prevention was observed in urea cycle enzymes among D-Galactosamine and treatment group rats. These results showed the effectiveness of ULP in stabilizing the functional status of mitochondrial and microsomal membrane which might be due to the presence of sulfated polysaccharide that could prevented the oxidative stress induced by D-Galactosamine intoxication. PMID:19000663

Devaki, Thiruvengadam; Sathivel, Arumugam; BalajiRaghavendran, Hanumantha Rao

2009-01-27

156

Alternating myocardial sympathetic neural function of athlete's heart in professional cycle racers examined with iodine-123-MIBG myocardial scintigraphy  

Microsoft Academic Search

Myocardial sympathetic neural function in professional athletes who had the long-term tremendous cardiac load has not been\\u000a fully investigated by myocardial iodine-123-metaiodobenzylguanidine (MIBG) uptake in comparison with power spectral analysis\\u000a (PSA) in electrocardiography. Eleven male professional cycle racers and age-matched 11 male healthy volunteers were enrolled\\u000a in this study. The low frequency components in the power spectral density (LF), the

Keiko Koyama; Tomio Inoue; Akira Hasegawa; Noboru Oriuchi; Eiichi Okamoto; Yumi Tomaru; Keigo Endo

2001-01-01

157

Damage evolution in an electron beam physical vapor deposited thermal barrier coating as a function of cycle temperature and time  

Microsoft Academic Search

Failure of thermal barrier coatings (TBCs) deposited on a single-crystal superalloy with a grit-blasted platinum modified nickel aluminide [?-(Ni, Pt) Al] bond coat has been studied as a function of thermal cycling temperature and time. One-hour cyclic furnace tests were conducted at 1100°C, 1121°C and 1151°C, and 24-h tests were run at 1121°C. It was found that all the samples

Swetha Sridharan; Liangde Xie; Eric H. Jordan; Maurice Gell; K. S. Murphy

2005-01-01

158

Li-Ion polymer cells thermal property changes as a function of cycle-life  

SciTech Connect

The impact of elevated temperature chargeedischarge cycling on thermal conductivity (K-value) of Lithium Ion Polymer (LIP) cells of various chemistries from three different manufacturers was investigated. These included high voltage (Graphite/LiCoO2:3.0e4.35 V), wide voltage (Si:C/LiCoO2:2.7e4.35 V) and conventional (Graphite/LiCoO2:3.0e4.2 V) chemistries. Investigation results show limited variability within the in-plane and through-plane K-values for the fresh cells with graphite-based anodes from all three suppliers. After 500 cycles at 45 C, in-plane and through-plane K-values of the high voltage cells reduced less vs. those for the wide voltage cells. Such results suggest that high temperature cycling could have a greater impact on thermal properties of Si:C cells than on the LIP cells with graphite (Gr) anode cells we tested. This difference is due to the excess swelling of Si:C-anode based cells vs. Gr-anode cells during cycling, especially at elevated temperatures. Thermal modeling is used to evaluate the impact of K-value changes, due to cycles at 45 C, on the cells internal heat propagation under internal short circuit condition that leads to localized meltdown of the separator.

Maleki, Hossein [Motorola Mobility; Wang, Hsin [ORNL; Porter, Wallace D [ORNL; Hallmark, Jerry [Motorola Mobility

2014-01-01

159

Aircraft Emission Scenarios Projected in Year 2015 for the NASA Technology Concept Aircraft (TCA) High Speed Civil Transport  

NASA Technical Reports Server (NTRS)

This report describes the development of a three-dimensional database of aircraft fuel burn and emissions (fuel burned, NOx, CO, and hydrocarbons) from projected fleets of high speed civil transports (HSCTs) on a universal airline network. Inventories for 500 and 1000 HSCT fleets, as well as the concurrent subsonic fleets, were calculated. The HSCT scenarios are calculated using the NASA technology concept airplane (TCA) and update an earlier report. These emissions inventories are available for use by atmospheric scientists conducting the Atmospheric Effects of Stratospheric Aircraft (AESA) modeling studies. Fuel burned and emissions of nitrogen oxides (NOx as NO2), carbon monoxide, and hydrocarbons have been calculated on a 1 degree latitude x 1 degree longitude x 1 kilometer pressure altitude grid and delivered to NASA as electronic files.

Baughcum, Steven L.; Henderson, Stephen C.

1998-01-01

160

Biostimulation induces syntrophic interactions that impact C, S and N cycling in a sediment microbial community  

SciTech Connect

Stimulation of subsurface microorganisms to induce reductive immobilization of metals is a promising approach for bioremediation, yet the overall microbial community response is typically poorly understood. Here we used community proteogenomics to test the hypothesis that excess input of acetate activates syntrophic interactions among autotrophs and heterotrophs. A flow-through sediment column was incubated in a groundwater well of an acetate-amended aquifer. Genomic sequences from the community recovered during microbial sulfate reduction were used to econstruct, de novo, near-complete genomes for Desulfobacter (Deltaproteobacteria) and relatives of Sulfurovum and Sulfurimonas (Epsilonproteobacteria), and Bacteroidetes. Partial genomes were obtained for Clostridiales (Firmicutes) and Desulfuromonadales-like Deltaproteobacteria. The majority of proteins identified by mass spectrometry corresponded to Desulfobacter-like species, and demonstrate the role of this organism in sulfate reduction (Dsr and APS), nitrogen-fixation (Nif) and acetate oxidation to CO2 during amendment. Results suggest less abundant Desulfuromonadales and Bacteroidetes also actively contributed to CO2 production via the TCA cycle. Proteomic data indicate that sulfide was partially re-oxidized by Epsilonproteobacteria through nitrate-dependent sulfide oxidation (using Nap, Nir, Nos, SQR and Sox), with CO2 fixed using the reverse TCA cycle. Modeling shows that this reaction was thermodynamically possible, and kinetically favorable relative to acetate-dependent denitrification. We conclude that high-levels of carbon amendment aimed to stimulate anaerobic heterotrophy led to carbon fixation in co-dependent chemoautotrophs. These results have implications for understanding complex ecosystem behavior, and show that high levels of organic carbon supplementation can expand the range of microbial functionalities accessible for ecosystem manipulation.

Handley, KM [University of California, Berkeley; Verberkmoes, Nathan C [ORNL; Steefel, Carl I [Lawrence Berkeley National Laboratory (LBNL); Sharon, I [University of California, Berkeley; Williams, Ken [Lawrence Berkeley National Laboratory (LBNL); Miller, CS [University of California, Berkeley; Frischkorn, Kyle C [University of California, Berkeley; Chourey, Karuna [ORNL; Thomas, Brian [University of California, Berkeley; Shah, Manesh B [ORNL; Long, Phil [Pacific Northwest National Laboratory (PNNL); Hettich, Robert {Bob} L [ORNL; Banfield, Jillian F. [University of California, Berkeley

2013-01-01

161

Defective Cell Cycle Checkpoint Functions in Melanoma Are Associated with Altered Patterns of Gene Expression  

Microsoft Academic Search

Defects in DNA damage responses may underlie genetic instability and malignant progression in melanoma. Cultures of normal human melanocytes (NHMs) and melanoma lines were analyzed to determine whether global patterns of gene expression could predict the efficacy of DNA damage cell cycle checkpoints that arrest growth and suppress genetic instability. NHMs displayed effective G1 and G2 checkpoint responses to ionizing

William K Kaufmann; Kathleen R Nevis; Pingping Qu; Joseph G Ibrahim; Tong Zhou; Yingchun Zhou; Dennis A Simpson; Jennifer Helms-Deaton; Marila Cordeiro-Stone; Dominic T Moore; Nancy E Thomas; Honglin Hao; Zhi Liu; Janiel M Shields; Glynis A Scott; Norman E Sharpless

2008-01-01

162

Variation in Risk Taking Behavior Among Female College Students as a Function of the Menstrual Cycle  

Microsoft Academic Search

There is some evidence that women are less likely to be raped during the mid-portion of the menstrual cycle. In order to determine if women might be behaving in ways to decrease their chances of sexual assault when they are most likely to conceive, female college students were asked to complete a questionnaire about their activities during the past 24

Tara J Chavanne; Gordon G Gallup

1998-01-01

163

Cinobufacini induced MDA-MB-231 cell apoptosis-associated cell cycle arrest and cytoskeleton function.  

PubMed

Cinobufacini is a traditional Chinese anti-tumor drug and widely used in clinic experiences. But little is known about its effect on the cells. In this study, the effects of cinobufacini on breast cancer MDA-MB-231 cell were evaluated by CCK-8 assay, and the data showed cinobufacini could inhibit the MDA-MB-231 cells growth effectively in dose-dependent and time-dependent manners. Cell apoptosis and cell cycle were detected by flow cytometry analysis. After the cells being treated with 50 ?g/mL cinobufacini for 48 h, the early apoptosis percentage (20.45 ± 1.46%) is much higher than the normal group (7.73 ± 1.21%). The cell cycle data indicated that cinobufacini caused a cell cycle arrest at S phase. What's more, cinobufacini can affect the disruption of cytoskeleton, and these alterations changed the cell-surface ultrastructure and the cell morphology which were detected by atomic force microscopy (AFM) at nanoscale level. It indicated that the cell membrane structure and cytoskeleton networks were destroyed and the cell tails were narrowed after the cell being treated with cinobufacini. The present study is to provide valuable new insights to understand the mechanism of the drug in anti-tumor process. Furthermore, the knowledge concerning the signaling of cell cycle is potentially important to clinical utility. PMID:22225634

Ma, Lina; Song, Bing; Jin, Hua; Pi, Jiang; Liu, Li; Jiang, Jinhuan; Cai, Jiye

2012-02-01

164

IL-7 functionally segregates the pro-B cell stage by regulating transcription of recombination mediators across cell cycle  

PubMed Central

Antigen receptor diversity involves the introduction of DNA double stranded breaks during lymphocyte development. To ensure fidelity, cleavage is confined to the G0/G1 phase of cell cycle. One established mechanism of regulation is through periodic degradation of the RAG2 recombinase protein. However, there are additional levels of protection. Here we show that cyclical changes in the IL-7R signaling pathway functionally segregate pro-B cells according to cell cycle status. In consequence, the level of a downstream effector of IL-7 signaling, phospho-STAT5, is inversely correlated with cell cycle expression of Rag, a key gene involved in recombination. Higher levels of phopho-STAT5 in S/G2 correlate with decreased Rag expression and Rag relocalization to pericentromeric heterochromatin (PCH). These cyclical changes in transcription and locus repositioning are ablated upon transformation with v-Abl, which renders STAT5 constitutively active across the cell cycle. We propose that this activity of the IL-7R/STAT5 pathway plays a critical protective role in development, complementing regulation of RAG2 at the protein level, to ensure that recombination does not occur during replication. Our data, suggesting that pro-B cells are not a single homogeneous population explain inconsistencies in the role of IL-7 signaling in regulating Igh recombination. PMID:22581861

Johnson, Kristen; Chaumeil, Julie; Micsinai, Mariann; Wang, Joy M.H.; Ramsey, Laura B.; Baracho, Gisele V; Rickert, Robert C; Strino, Francesco; Kluger, Yuval; Farrar, Michael A.; Skok, Jane A.

2012-01-01

165

Decoupling of soil nutrient cycles as a function of aridity in global drylands.  

PubMed

The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humid ecosystems (drylands) because their biological activity is mainly driven by water availability. The increase in aridity predicted for the twenty-first century in many drylands worldwide may therefore threaten the balance between these cycles, differentially affecting the availability of essential nutrients. Here we evaluate how aridity affects the balance between C, N and P in soils collected from 224 dryland sites from all continents except Antarctica. We find a negative effect of aridity on the concentration of soil organic C and total N, but a positive effect on the concentration of inorganic P. Aridity is negatively related to plant cover, which may favour the dominance of physical processes such as rock weathering, a major source of P to ecosystems, over biological processes that provide more C and N, such as litter decomposition. Our findings suggest that any predicted increase in aridity with climate change will probably reduce the concentrations of N and C in global drylands, but increase that of P. These changes would uncouple the C, N and P cycles in drylands and could negatively affect the provision of key services provided by these ecosystems. PMID:24172979

Delgado-Baquerizo, Manuel; Maestre, Fernando T; Gallardo, Antonio; Bowker, Matthew A; Wallenstein, Matthew D; Quero, Jose Luis; Ochoa, Victoria; Gozalo, Beatriz; García-Gómez, Miguel; Soliveres, Santiago; García-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Escolar, Cristina; Arredondo, Tulio; Barraza-Zepeda, Claudia; Bran, Donaldo; Carreira, José Antonio; Chaieb, Mohamed; Conceição, Abel A; Derak, Mchich; Eldridge, David J; Escudero, Adrián; Espinosa, Carlos I; Gaitán, Juan; Gatica, M Gabriel; Gómez-González, Susana; Guzman, Elizabeth; Gutiérrez, Julio R; Florentino, Adriana; Hepper, Estela; Hernández, Rosa M; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Liu, Jushan; Mau, Rebecca L; Miriti, Maria; Monerris, Jorge; Naseri, Kamal; Noumi, Zouhaier; Polo, Vicente; Prina, Aníbal; Pucheta, Eduardo; Ramírez, Elizabeth; Ramírez-Collantes, David A; Romão, Roberto; Tighe, Matthew; Torres, Duilio; Torres-Díaz, Cristian; Ungar, Eugene D; Val, James; Wamiti, Wanyoike; Wang, Deli; Zaady, Eli

2013-10-31

166

Decoupling of soil nutrient cycles as a function of aridity in global drylands  

NASA Astrophysics Data System (ADS)

The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humid ecosystems (drylands) because their biological activity is mainly driven by water availability. The increase in aridity predicted for the twenty-first century in many drylands worldwide may therefore threaten the balance between these cycles, differentially affecting the availability of essential nutrients. Here we evaluate how aridity affects the balance between C, N and P in soils collected from 224 dryland sites from all continents except Antarctica. We find a negative effect of aridity on the concentration of soil organic C and total N, but a positive effect on the concentration of inorganic P. Aridity is negatively related to plant cover, which may favour the dominance of physical processes such as rock weathering, a major source of P to ecosystems, over biological processes that provide more C and N, such as litter decomposition. Our findings suggest that any predicted increase in aridity with climate change will probably reduce the concentrations of N and C in global drylands, but increase that of P. These changes would uncouple the C, N and P cycles in drylands and could negatively affect the provision of key services provided by these ecosystems.

Delgado-Baquerizo, Manuel; Maestre, Fernando T.; Gallardo, Antonio; Bowker, Matthew A.; Wallenstein, Matthew D.; Quero, Jose Luis; Ochoa, Victoria; Gozalo, Beatriz; García-Gómez, Miguel; Soliveres, Santiago; García-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Escolar, Cristina; Arredondo, Tulio; Barraza-Zepeda, Claudia; Bran, Donaldo; Carreira, José Antonio; Chaieb, Mohamed; Conceição, Abel A.; Derak, Mchich; Eldridge, David J.; Escudero, Adrián; Espinosa, Carlos I.; Gaitán, Juan; Gatica, M. Gabriel; Gómez-González, Susana; Guzman, Elizabeth; Gutiérrez, Julio R.; Florentino, Adriana; Hepper, Estela; Hernández, Rosa M.; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Liu, Jushan; Mau, Rebecca L.; Miriti, Maria; Monerris, Jorge; Naseri, Kamal; Noumi, Zouhaier; Polo, Vicente; Prina, Aníbal; Pucheta, Eduardo; Ramírez, Elizabeth; Ramírez-Collantes, David A.; Romão, Roberto; Tighe, Matthew; Torres, Duilio; Torres-Díaz, Cristian; Ungar, Eugene D.; Val, James; Wamiti, Wanyoike; Wang, Deli; Zaady, Eli

2013-10-01

167

ABBREVIATIONS: MPO, myeloperoxidase; HAP, horseradish peroxidase; GSH, reduced glutathione; TCA, trichloroacetic acid; HPLC, high pressure liquid chromatography; FAB, fast atom bombardment; MS, mass spectrometry; GC, gas chromatography.  

E-print Network

ABBREVIATIONS: MPO, myeloperoxidase; HAP, horseradish peroxidase; GSH, reduced glutathione; TCA Peroxidase D. A. EASTMOND, M. T. SMITH, L. 0. RUZO, and D. ROSS Department of Biomedical and Environmental SUMMARY The oxidation of phenol catalyzed by human myeloperoxidase and horseradish peroxidase resulted

California at Berkeley, University of

168

Stability of amine-functionalized cellulose during temperature-vacuum-swing cycling for CO2 capture from air.  

PubMed

The stability of amine-functionalized nanofibrilated cellulose sorbent for direct air capture of CO2 is investigated during temperature-vacuum-swing (TVS) cycling. The presence of O2 at 90 °C degrades the sorbent, reducing its CO2 adsorption capacity by 30% after 15 h of treatment in moist air with a dew point of 22 °C. In contrast, exposure to moist CO2 at 90 °C with a dew point of 22 °C does not deteriorate its CO2 adsorption capacity after 15 h. Performing 100 TVS consecutive cycles, with CO2 adsorption from ambient air containing 400-530 ppm CO2 at 30 °C and 60% relative humidity and with CO2 desorption at 90 °C and 30 mbar, resulted in a reduction of the equilibrium CO2 adsorption capacity by maximum 5%. The average CO2 adsorption capacity during TVS cyclic operation is 0.90 mmol CO2/g. PMID:23919493

Gebald, Christoph; Wurzbacher, Jan A; Tingaut, Philippe; Steinfeld, Aldo

2013-09-01

169

DNA Damage-Induced Cell Cycle Regulation and Function of Novel Chk2 Phosphoresidues  

Microsoft Academic Search

Chk2 kinase is activated by DNA damage to regulate cell cycle arrest, DNA repair, and apoptosis. Phos- phorylation of Chk2 in vivo by ataxia telangiectasia-mutated (ATM) on threonine 68 (T68) initiates a phos- phorylation cascade that promotes the full activity of Chk2. We identified three serine residues (S19, S33, and S35) on Chk2 that became phosphorylated in vivo rapidly and

Giacomo Buscemi; Luigi Carlessi; Laura Zannini; Sofia Lisanti; Enrico Fontanella; Silvana Canevari; Domenico Delia

2006-01-01

170

Converting chemical energy into electricity through a functionally cooperating device with diving-surfacing cycles.  

PubMed

A smart device that can dive or surface in aqueous medium has been developed by combining a pH-responsive surface with acid-responsive magnesium. The diving-surfacing cycles can be used to convert chemical energy into electricity. During the diving-surfacing motion, the smart device cuts magnetic flux lines and produces a current, demonstrating that motional energy can be realized by consuming chemical energy of magnesium, thus producing electricity. PMID:25146589

Song, Mengmeng; Cheng, Mengjiao; Ju, Guannan; Zhang, Yajun; Shi, Feng

2014-11-01

171

Pneumocystis carinii Uses a Functional Cdc13 B-Type Cyclin Complex during Its Life Cycle  

Microsoft Academic Search

Pneumocystis carinii causes severe pneumonia in immunocom- promised patients. Recent studies indicate that P. carinii uses a Cdc2 cyclin-dependent kinase to control its proliferation. To further study the regulation of the life cycle of P. carinii , we characterized the P. carinii B-type cyclin termed Cdc13, whose binding to Cdc2 is necessary for kinase activity. Antibodies to B-type cyclins (Cdc13)

Theodore J. Kottom; Charles F. Thomas; Kamal K. Mubarak; Edward B. Leof; Andrew H. Limper

172

The function of FOXO1 in the late phases of the cell cycle is suppressed by PLK1-mediated phosphorylation  

PubMed Central

Polo-like kinase 1 (PLK1) plays crucial roles in multiple stages of cell division. Our previous studies suggest that global transcriptional regulation by PLK1 may contribute to its multiple functions. PLK1 depletion is associated with a decrease in cell viability and the induction of apoptosis; however, the underlying mechanisms are not completely understood. Here, we report that forkhead box protein O1 (FOXO1) is a novel physiological substrate of PLK1. FOXO1 is at the interface of crucial cellular processes, orchestrating programs of gene expression that regulate apoptosis, cell cycle progression, and oxidative-stress resistance. PLK1 interacts with and phosphorylates FOXO1, mainly at the G2/M phase of the cell cycle. PLK1-mediated phosphorylation leads to the impairment of FOXO1’s transcriptional activity in an Akt-independent manner. By immunofluorescence staining and subcellular fractionation, we demonstrate that PLK1-induced FOXO1 phosphorylation causes its nuclear exclusion. Furthermore, PLK1-mediated phosphorylation of FOXO1 negatively regulates its pro-apoptotic function and abrogates its ability to delay entry into and progression through G2/M transition. Therefore, our results suggest that PLK1 abrogates the inhibitory effects of FOXO1 on cell growth and survival to ensure timely cell cycle progression. This study not only reveals a novel and major regulatory mechanism of FOXO1 at the late phases of the cell cycle, but also provides new insight into the molecular mechanisms by which PLK1 inhibition leads to growth arrest and cell death. PMID:24407358

Yuan, Chengfu; Wang, Lei; Zhou, Liang; Fu, Zheng

2014-01-01

173

PP2A function toward mitotic kinases and substrates during the cell cycle  

PubMed Central

To maintain cellular homeostasis against the demands of the extracellular environment, a precise regulation of kinases and phosphatases is essential. In cell cycle regulation mechanisms, activation of the cyclin-dependent kinase (CDK1) and cyclin B complex (CDK1:cyclin B) causes a remarkable change in protein phosphorylation. Activation of CDK1:cyclin B is regulated by two auto-amplification loops-CDK1:cyclin B activates Cdc25, its own activating phosphatase, and inhibits Wee1, its own inhibiting kinase. Recent biological evidence has revealed that the inhibition of its counteracting phosphatase activity also occurs, and it is parallel to CDK1:cyclin B activation during mitosis. Phosphatase regulation of mitotic kinases and their substrates is essential to ensure that the progression of the cell cycle is ordered. Outlining how the mutual control of kinases and phosphatases governs the localization and timing of cell division will give us a new understanding about cell cycle regulation. [BMB Reports 2013; 46(6): 289-294] PMID:23790971

Jeong, Ae Lee; Yang, Young

2013-01-01

174

EFFECTS OF LAND USE CHANGES ON THE FUNCTIONING OF SOILS AND WATERSHEDS OF CENTRAL BRAZIL SAVANNAS: PHASE 2, IMPACTS ON NUTRIENT AND CARBON CYCLES AND TRACE GAS EXCHANGE  

EPA Science Inventory

This research is funded through an interagency agreement with NASA. The research in this project is contributing to assessments of the effects of land use in central Brazil on: 1) the stocks and cycling rates of carbon and nutrient cycling; 2) the function and structure of soil ...

175

Rates of insulin secretion in INS-1 cells are enhanced by coupling to anaplerosis and Kreb's cycle flux independent of ATP synthesis  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer We studied media effects on mechanisms of insulin secretion of INS-1 cells. Black-Right-Pointing-Pointer Insulin secretion was higher in DMEM than KRB despite identical ATP synthesis rates. Black-Right-Pointing-Pointer Insulin secretion rates correlated with rates of anaplerosis and TCA cycle. Black-Right-Pointing-Pointer Mitochondria metabolism and substrate cycles augment secretion signal of ATP. -- Abstract: Mechanistic models of glucose stimulated insulin secretion (GSIS) established in minimal media in vitro, may not accurately describe the complexity of coupling metabolism with insulin secretion that occurs in vivo. As a first approximation, we have evaluated metabolic pathways in a typical growth media, DMEM as a surrogate in vivo medium, for comparison to metabolic fluxes observed under the typical experimental conditions using the simple salt-buffer of KRB. Changes in metabolism in response to glucose and amino acids and coupling to insulin secretion were measured in INS-1 832/13 cells. Media effects on mitochondrial function and the coupling efficiency of oxidative phosphorylation were determined by fluorometrically measured oxygen consumption rates (OCRs) combined with {sup 31}P NMR measured rates of ATP synthesis. Substrate preferences and pathways into the TCA cycle, and the synthesis of mitochondrial 2nd messengers by anaplerosis were determined by {sup 13}C NMR isotopomer analysis of the fate of [U-{sup 13}C] glucose metabolism. Despite similar incremental increases in insulin secretion, the changes of OCR in response to increasing glucose from 2.5 to 15 mM were blunted in DMEM relative to KRB. Basal and stimulated rates of insulin secretion rates were consistently higher in DMEM, while ATP synthesis rates were identical in both DMEM and KRB, suggesting greater mitochondrial uncoupling in DMEM. The relative rates of anaplerosis, and hence synthesis and export of 2nd messengers from the mitochondria were found to be similar in DMEM to those in KRB. And, the correlation of total PC flux with insulin secretion rates in DMEM was found to be congruous with the correlation in KRB. Together, these results suggest that signaling mechanisms associated with both TCA cycle flux and with anaplerotic flux, but not ATP production, may be responsible for the enhanced rates of insulin secretion in more complex, and physiologically-relevant media.

Cline, Gary W., E-mail: gary.cline@yale.edu [The Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520 (United States); Department of Surgery, University of Minnesota-Twin Cities, Minneapolis, MN 55455 (United States); Pongratz, Rebecca L.; Zhao, Xiaojian [The Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520 (United States)] [The Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520 (United States); Papas, Klearchos K. [Department of Surgery, University of Minnesota-Twin Cities, Minneapolis, MN 55455 (United States)] [Department of Surgery, University of Minnesota-Twin Cities, Minneapolis, MN 55455 (United States)

2011-11-11

176

A centrosomal function for the human Nek2 protein kinase, a member of the NIMA family of cell cycle regulators.  

PubMed Central

Nek2, a mammalian protein kinase of unknown function, is closely related to the mitotic regulator NIMA of Aspergillus nidulans. Here we show by both immunofluorescence microscopy and biochemical fractionation that human Nek2 localizes to the centrosome. Centrosome association occurs throughout the cell cycle, including all stages of mitosis, and is independent of microtubules. Overexpression of active Nek2 induces a striking splitting of centrosomes, whereas prolonged expression of either active or inactive Nek2 leads to dispersal of centrosomal material and loss of a focused microtubule-nucleating activity. Surprisingly, this does not prevent entry into mitosis, as judged by the accumulation of mitotically arrested cells induced by co-expression of a non-destructible B-type cyclin. These results bear on the dynamic function of centrosomes at the onset of mitosis. Moreover, they indicate that one function of mammalian Nek2 relates to the centrosome cycle and thus provide a new perspective on the role of NIMA-related kinases. PMID:9430639

Fry, A M; Meraldi, P; Nigg, E A

1998-01-01

177

Functional relationships between spatio-temporal vegetation dynamics and the water cycle  

NASA Astrophysics Data System (ADS)

The land use / land cover of an area is a key parameter within the hydrological cycle. In the framework of IMPETUS (Integrated management project for a sustainable use of fresh water) the Vegetation Group are investigating the complex interactions between the hydrological cycle and vegetation in two river catchments, situated north and south of the Sahara (Draa in Morocco and Ouémé in Benin). A major research focus is the assessment of land use / land cover (LUCC) and the derivation of their key parameters such as leaf area index, transpiration and biomass production. This is achieved using satellite imagery of different resolutions (e.g.:LANDSAT, MODIS) that are analysed and verified by intensive ground-truthing and comprehensive in-situ measurements. The vegetation dynamics are also being investigated via a series of remote sensing images at different temporal scales. This is being undertaken in order to understand the underlying processes, and their impact on the hydrological cycle. Therefore, the ecosystem's stability and its regeneration potential are in focus of the research activities of the Vegetation Group. The importance of quantifying and understanding vegetation change is critical, given that the research sites there have experience dramatic land use / land cover change. Between 1986 and 2000 more than 32% of the dense forest in the research site in Benin has been cut. The results of these investigations are related to the output of climatological and hydrological models. Socio-economic factors driving land cover / land use changes are also considered, and integrated into a model describing land cover / land use changes. Land consumption and food security are closely related with the efficiency of agriculture. The Agricultural Group is therefore investigating the influence of different types of fertilisers on the yield across 150 research fields. Initial results show that water use efficiency of crops may be increased by more than 30% using special varieties and fertiliser addition. Based on results of these multi-dimensional research activities, scenarios for the development of the land cover / land use, and the impact on the hydrological cycle under different boundary conditions can be develop. This is an important step towards a sustainable development plan for the regions, particularly in regards to available fresh water resources.

Thamm, H.-P.; Menz, G.; Goldbach, H.; Poremski, S.; Juergens, N.; Burkhardt, J.; Finck, M.; Orthmann, B.; Staudinger, M.; Gresens, F.

2003-04-01

178

Phylogeny and phylogeography of functional genes shared among seven terrestrial subsurface metagenomes reveal N-cycling and microbial evolutionary relationships.  

PubMed

Comparative studies on community phylogenetics and phylogeography of microorganisms living in extreme environments are rare. Terrestrial subsurface habitats are valuable for studying microbial biogeographical patterns due to their isolation and the restricted dispersal mechanisms. Since the taxonomic identity of a microorganism does not always correspond well with its functional role in a particular community, the use of taxonomic assignments or patterns may give limited inference on how microbial functions are affected by historical, geographical and environmental factors. With seven metagenomic libraries generated from fracture water samples collected from five South African mines, this study was carried out to (1) screen for ubiquitous functions or pathways of biogeochemical cycling of CH4, S, and N; (2) to characterize the biodiversity represented by the common functional genes; (3) to investigate the subsurface biogeography as revealed by this subset of genes; and (4) to explore the possibility of using metagenomic data for evolutionary study. The ubiquitous functional genes are NarV, NPD, PAPS reductase, NifH, NifD, NifK, NifE, and NifN genes. Although these eight common functional genes were taxonomically and phylogenetically diverse and distinct from each other, the dissimilarity between samples did not correlate strongly with geographical or environmental parameters or residence time of the water. Por genes homologous to those of Thermodesulfovibrio yellowstonii detected in all metagenomes were deep lineages of Nitrospirae, suggesting that subsurface habitats have preserved ancestral genetic signatures that inform the study of the origin and evolution of prokaryotes. PMID:25400621

Lau, Maggie C Y; Cameron, Connor; Magnabosco, Cara; Brown, C Titus; Schilkey, Faye; Grim, Sharon; Hendrickson, Sarah; Pullin, Michael; Sherwood Lollar, Barbara; van Heerden, Esta; Kieft, Thomas L; Onstott, Tullis C

2014-01-01

179

Phylogeny and phylogeography of functional genes shared among seven terrestrial subsurface metagenomes reveal N-cycling and microbial evolutionary relationships  

PubMed Central

Comparative studies on community phylogenetics and phylogeography of microorganisms living in extreme environments are rare. Terrestrial subsurface habitats are valuable for studying microbial biogeographical patterns due to their isolation and the restricted dispersal mechanisms. Since the taxonomic identity of a microorganism does not always correspond well with its functional role in a particular community, the use of taxonomic assignments or patterns may give limited inference on how microbial functions are affected by historical, geographical and environmental factors. With seven metagenomic libraries generated from fracture water samples collected from five South African mines, this study was carried out to (1) screen for ubiquitous functions or pathways of biogeochemical cycling of CH4, S, and N; (2) to characterize the biodiversity represented by the common functional genes; (3) to investigate the subsurface biogeography as revealed by this subset of genes; and (4) to explore the possibility of using metagenomic data for evolutionary study. The ubiquitous functional genes are NarV, NPD, PAPS reductase, NifH, NifD, NifK, NifE, and NifN genes. Although these eight common functional genes were taxonomically and phylogenetically diverse and distinct from each other, the dissimilarity between samples did not correlate strongly with geographical or environmental parameters or residence time of the water. Por genes homologous to those of Thermodesulfovibrio yellowstonii detected in all metagenomes were deep lineages of Nitrospirae, suggesting that subsurface habitats have preserved ancestral genetic signatures that inform the study of the origin and evolution of prokaryotes. PMID:25400621

Lau, Maggie C. Y.; Cameron, Connor; Magnabosco, Cara; Brown, C. Titus; Schilkey, Faye; Grim, Sharon; Hendrickson, Sarah; Pullin, Michael; Sherwood Lollar, Barbara; van Heerden, Esta; Kieft, Thomas L.; Onstott, Tullis C.

2014-01-01

180

Oligonucleotide Microarray for the Study of Functional Gene Diversity in the Nitrogen Cycle in the Environment  

Microsoft Academic Search

The analysis of functional diversity and its dynamics in the environment is essential for understanding the microbial ecology and biogeochemistry of aquatic systems. Here we describe the development and optimization of a DNA microarray method for the detection and quantification of functional genes in the environment and report on their preliminary application to the study of the denitrification gene nirS

Gaspar Taroncher-Oldenburg; Erin M. Griner; Chris A. Francis; Bess B. Ward

2003-01-01

181

Radiation-induced cardiomyopathy as a function of radiation beam gating to the cardiac cycle  

NASA Astrophysics Data System (ADS)

Portions of the heart are often unavoidably included in the primary treatment volume during thoracic radiotherapy, and radiation-induced heart disease has been observed as a treatment-related complication. Such complications have been observed in humans following radiation therapy for Hodgkin's disease and treatment of the left breast for carcinoma. Recent attempts have been made to prevent re-stenosis following angioplasty procedures using external beam irradiation. These attempts were not successful, however, due to the large volume of heart included in the treatment field and subsequent cardiac morbidity. We suggest a mechanism for sparing the heart from radiation damage by synchronizing the radiation beam with the cardiac cycle and delivering radiation only when the heart is in a relatively hypoxic state. We present data from a rat model testing this hypothesis and show that radiation damage to the heart can be altered by synchronizing the radiation beam with the cardiac cycle. This technique may be useful in reducing radiation damage to the heart secondary to treatment for diseases such as Hodgkin's disease and breast cancer.

Gladstone, David J.; Flanagan, Michael F.; Southworth, Jean B.; Hadley, Vaughn; Thibualt, Melissa Wei; Hug, Eugen B.; Hoopes, P. Jack

2004-04-01

182

Environmental impacts on the diversity of methane-cycling microbes and their resultant function  

PubMed Central

Methane is an important anthropogenic greenhouse gas that is produced and consumed in soils by microorganisms responding to micro-environmental conditions. Current estimates show that soil consumption accounts for 5–15% of methane removed from the atmosphere on an annual basis. Recent variability in atmospheric methane concentrations has called into question the reliability of estimates of methane consumption and calls for novel approaches in order to predict future atmospheric methane trends. This review synthesizes the environmental and climatic factors influencing the consumption of methane from the atmosphere by non-wetland, terrestrial soil microorganisms. In particular, we focus on published efforts to connect community composition and diversity of methane-cycling microbial communities to observed rates of methane flux. We find abundant evidence for direct connections between shifts in the methane-cycling microbial community, due to climate and environmental changes, and observed methane flux levels. These responses vary by ecosystem and associated vegetation type. This information will be useful in process-based models of ecosystem methane flux responses to shifts in environmental and climatic parameters. PMID:23966984

Aronson, Emma L.; Allison, Steven D.; Helliker, Brent R.

2013-01-01

183

Expression and localization of nodal in bovine oviduct and uterus during different functional stages of oestrus cycle and pregnancy.  

PubMed

Members of TGF-? superfamily play a major role in the endometrial changes involved in the establishment and maintenance of pregnancy. Their deregulated expression and action could lead to absolute or partial failure of embryo implantation. Nonetheless, the precise function and mechanism of many of these cytokines remain unclear. Nodal, a transforming growth factor beta (TGF-?) superfamily member, was characterized in the human and rodent uterus and implicated in the tissue remodeling events during menstruation and embryo implantation. In order to study its possible role in the cattle reproductive process, we have analyzed Nodal expression pattern and localization in the oviduct and uterine horn during the oestrus cycle and early pregnancy (day 20). Nodal was detected both in oviduct and uterus during either the oestrus cycle or pregnancy; however, it shows a differential expression profile in the uterine horn at dioestrus and pregnancy, decreasing 1.5 and 1.4 folds in comparison with oestrus. Nodal immunostaining intensity was observed in stromal and in epithelial cells of the surface and the glandular epithelium. The staining pattern correlates with the RT-qPCR expression profile. This work is the first to evidence the presence of Nodal in the bovine reproductive tract; our data suggest that Nodal is a novel cytokine that would be involved in the remodelling occurring in the endometrium of cattle during the oestrus cycle and in the embryo implantation. The identification of new molecules that participate in endometrium cycling and/or pregnancy may be useful for predicting the ability of the uterine tissue to establish and maintain pregnancy or for detecting the infertility processes. These results highlight Nodal as a possible novel marker of the fertility process, nevertheless further studies should be done to determine its role in the reproductive system. PMID:23052837

Argañaraz, Martin Eduardo; Apichela, Silvana Andrea; Kenngott, Rebecca; Vermeheren, Margarethe; Rodler, Daniela; Palma, Gustavo Adolfo; Miceli, Dora Cristina; Sinowatz, Fred

2013-01-01

184

rre37 Overexpression Alters Gene Expression Related to the Tricarboxylic Acid Cycle and Pyruvate Metabolism in Synechocystis sp. PCC 6803  

PubMed Central

The tricarboxylic acid (TCA) cycle and pyruvate metabolism of cyanobacteria are unique and important from the perspectives of biology and biotechnology research. Rre37, a response regulator induced by nitrogen depletion, activates gene expression related to sugar catabolism. Our previous microarray analysis has suggested that Rre37 controls the transcription of genes involved in sugar catabolism, pyruvate metabolism, and the TCA cycle. In this study, quantitative real-time PCR was used to measure the transcript levels of 12?TCA cycle genes and 13 pyruvate metabolism genes. The transcripts of 6 genes (acnB, icd, ppc, pyk1, me, and pta) increased after 4?h of nitrogen depletion in the wild-type GT strain but the induction was abolished by rre37 overexpression. The repression of gene expression of fumC, ddh, and ackA caused by nitrogen depletion was abolished by rre37 overexpression. The expression of me was differently affected by rre37 overexpression, compared to the other 24 genes. These results indicate that Rre37 differently controls the genes of the TCA cycle and pyruvate metabolism, implying the key reaction of the primary in this unicellular cyanobacterium. PMID:25614900

Iijima, Hiroko; Watanabe, Atsuko; Takanobu, Junko; Hirai, Masami Yokota; Osanai, Takashi

2014-01-01

185

The role of the tricarboxylic acid cycle in citric acid accumulation by Aspergillus niger  

Microsoft Academic Search

Determinations of the momentary levels of various intermediates related to the activity of the tricarboxylic acid cycle have been made during citric acid production in high-accumulating (manganese deficient) and lowaccumulating (manganese supplemented) mycelia of Aspergillus niger. During the growth period the levels of almost all TCA cycle acids, with the exception of 2-oxo-acids, were unusually high; during the induction phase

C. P. Kubicek; M. Röhr

1978-01-01

186

The role of surface chemical analysis in a study to select replacement processes for TCA vapor degreasing  

NASA Technical Reports Server (NTRS)

The role of surface-sensitive chemical analysis (ESCA, AES, and SIMS) in a study to select a process to replace 1, 1, 1-trichloroethane (TCA) vapor degreasing as a steel and aluminum bonding surface preparation method is described. The effort was primarily concerned with spray-in-air cleaning processes involving aqueous alkaline and semi-aqueous cleaners and a contamination sensitive epoxy-to-metal bondline. While all five cleaners tested produced bonding strength results equal to or better than those produced by vapor degreasing, the aqueous alkaline cleaners yielded results which were superior to those produced by the semi-aqueous cleaners. The main reason for the enhanced performance appears to be a silicate layer left behind by the aqueous alkaline cleaners. The silicate layer increases the polarity of the surface and enhances epoxy-to-metal bonding. On the other hand, one of the semi-aqueous cleaners left a nonpolar carbonaceous residue which appeared to have a negative effect on epoxy-to-metal bonding. Differences in cleaning efficiency between cleaners/processes were also identified. These differences in surface chemistry, which were sufficient to affect bonding, were not detected by conventional chemical analysis techniques.

Lesley, Michael W.; Davis, Lawrence E.; Moulder, John F.; Carlson, Brad A.

1995-01-01

187

Human Liver Methionine Cycle: MAT1A and GNMT Gene Resequencing, Functional Genomics, and Hepatic Genotype-Phenotype Correlation  

PubMed Central

The “methionine cycle” plays a critical role in the regulation of concentrations of (S)-adenosylmethionine (AdoMet), the major biological methyl donor. We set out to study sequence variation in genes encoding the enzyme that synthesizes AdoMet in liver, methionine adenosyltransferase 1A (MAT1A) and the major hepatic AdoMet using enzyme, glycine N-methyltransferase (GNMT), as well as functional implications of that variation. We resequenced MAT1A and GNMT using DNA from 288 subjects of three ethnicities, followed by functional genomic and genotype-phenotype correlation studies performed with 268 hepatic biopsy samples. We identified 44 and 42 polymorphisms in MAT1A and GNMT, respectively. Quantitative Western blot analyses for the human liver samples showed large individual variation in MAT1A and GNMT protein expression. Genotype-phenotype correlation identified two genotyped single-nucleotide polymorphisms (SNPs), reference SNP (rs) 9471976 (corrected p = 3.9 × 10?10) and rs11752813 (corrected p = 1.8 × 10?5), and 42 imputed SNPs surrounding GNMT that were significantly associated with hepatic GNMT protein levels (corrected p values < 0.01). Reporter gene studies showed that variant alleles for both genotyped SNPs resulted in decreased transcriptional activity. Correlation analyses among hepatic protein levels for methionine cycle enzymes showed significant correlations between GNMT and MAT1A (p = 1.5 × 10?3) and between GNMT and betaine homocysteine methyltransferase (p = 1.6 × 10?7). Our discovery of SNPs that are highly associated with hepatic GNMT protein expression as well as the “coordinate regulation” of methionine cycle enzyme protein levels provide novel insight into the regulation of this important human liver biochemical pathway. PMID:22807109

Ji, Yuan; Nordgren, Kendra K. S.; Chai, Yubo; Hebbring, Scott J.; Jenkins, Gregory D.; Abo, Ryan P.; Peng, Yi; Pelleymounter, Linda L.; Moon, Irene; Eckloff, Bruce W.; Chai, Xiaoshan; Zhang, Jianping; Fridley, Brooke L.; Yee, Vivien C.; Wieben, Eric D.

2012-01-01

188

Catabolism of ?-Ketoglutarate by a sucA Mutant of Bradyrhizobium japonicum: Evidence for an Alternative Tricarboxylic Acid Cycle  

PubMed Central

A complete tricarboxylic acid (TCA) cycle is generally considered necessary for energy production from the dicarboxylic acid substrates malate, succinate, and fumarate. However, a Bradyrhizobium japonicum sucA mutant that is missing ?-ketoglutarate dehydrogenase is able to grow on malate as its sole source of carbon. This mutant also fixes nitrogen in symbiosis with soybean, where dicarboxylic acids are its principal carbon substrate. Using a flow chamber system to make direct measurements of oxygen consumption and ammonium excretion, we confirmed that bacteroids formed by the sucA mutant displayed wild-type rates of respiration and nitrogen fixation. Despite the absence of ?-ketoglutarate dehydrogenase activity, whole cells of the mutant were able to decarboxylate ?-[U-14C]ketoglutarate and [U-14C]glutamate at rates similar to those of wild-type B. japonicum, indicating that there was an alternative route for ?-ketoglutarate catabolism. Because cell extracts from B. japonicum decarboxylated [U-14C]glutamate very slowly, the ?-aminobutyrate shunt is unlikely to be the pathway responsible for ?-ketoglutarate catabolism in the mutant. In contrast, cell extracts from both the wild type and mutant showed a coenzyme A (CoA)-independent ?-ketoglutarate decarboxylation activity. This activity was independent of pyridine nucleotides and was stimulated by thiamine PPi. Thin-layer chromatography showed that the product of ?-ketoglutarate decarboxylation was succinic semialdehyde. The CoA-independent ?-ketoglutarate decarboxylase, along with succinate semialdehyde dehydrogenase, may form an alternative pathway for ?-ketoglutarate catabolism, and this pathway may enhance TCA cycle function during symbiotic nitrogen fixation. PMID:10781553

Green, Laura S.; Li, Youzhong; Emerich, David W.; Bergersen, Fraser J.; Day, David A.

2000-01-01

189

An Examination of the Stretch-Shortening Cycle of the Dorsiflexors and Evertors in Uninjured and Functionally Unstable Ankles  

PubMed Central

Objective: To determine if there were differences in concentric peak torque/body-weight (PT/BW) ratios and concentric time to peak torque (TPT) of the dorsiflexors and evertors in uninjured and functionally unstable ankles using a stretch-shortening cycle (SSC) protocol on an isokinetic dynamometer. Design and Setting: We employed a case-control study design to examine the test subjects in a climate-controlled athletic training/sports medicine research laboratory. Subjects: Thirty subjects volunteered to participate in this study, 15 with unilateral functional ankle instability and 15 matched controls. Measurements: Participants were assessed isokinetically using an SSC protocol for the dorsiflexors and evertors at 120 and 240°·s?1, bilaterally. Strength was assessed using PT values normalized for body mass. Concentric TPT measurements were also compared between the groups. Results: No differences in concentric PT/BW ratios or concentric TPT were evident between the groups (P > .05). Additionally, there were no differences in these measurements between the ankles for the same motion and speed between the ankles in the subjects with functional instability. Conclusions: Using the SSC protocol as a measure of ankle function and the stretch-reflex phenomenon, we found no evidence to support the notion that differences in strength and TPT in the active, conscious state exist between those with functional ankle instability and a group of healthy control subjects. PMID:12937573

Porter, Gary K.; Kaminski, Thomas W.; Hatzel, Brian; Powers, Michael E.; Horodyski, MaryBeth

2002-01-01

190

p53 functions as a cell cycle control protein in osteosarcomas.  

PubMed Central

Mutations in the p53 gene have been associated with a wide range of human tumors, including osteosarcomas. Although it has been shown that wild-type p53 can block the ability of E1a and ras to cotransform primary rodent cells, it is poorly understood why inactivation of the p53 gene is important for tumor formation. We show that overexpression of the gene encoding wild-type p53 blocks the growth of osteosarcoma cells. The growth arrest was determined to be due to an inability of the transfected cells to progress into S phase. This suggests that the role of the p53 gene as an antioncogene may be in controlling the cell cycle in a fashion analogous to the check-point control genes in Saccharomyces cerevisiae. Images PMID:2233717

Diller, L; Kassel, J; Nelson, C E; Gryka, M A; Litwak, G; Gebhardt, M; Bressac, B; Ozturk, M; Baker, S J; Vogelstein, B

1990-01-01

191

Genetic analysis of punt, a type II Dpp receptor that functions throughout the Drosophila melanogaster life cycle.  

PubMed Central

TGF-beta (transforming growth factor-beta-) mediated signal transduction affects growth and patterning in a variety of organisms. Here we report a genetic characterization of the Drosophila punt gene that encodes a type II serine/threonine kinase TGF-beta/Dpp (Decapentaplegic) receptor. Although the punt gene was originally identified based on its requirement for embryonic dorsal closure, we have documented multiple periods of punt activity throughout the Drosophila life cycle. We demonstrate that potentially related embryonic punt phenotypes, defects in dorsoventral patterning and dorsal closure, correspond to distinct maternal and zygotic requirements for punt. In addition, we document postembryonic requirements for punt activity. The tight correspondence between both embryonic and postembryonic loss-of-function punt and dpp phenotypes implicates a role for Punt in mediating virtually all Dpp signaling events in Drosophila. Finally, our comparison of punt homoallelic and heteroallelic phenotypes provides direct evidence for interallelic complementation. Taken together, these results suggest that the Punt protein functions as a dimer or higher order multimer throughout the Drosophila life cycle. PMID:9504926

Simin, K; Bates, E A; Horner, M A; Letsou, A

1998-01-01

192

Endogenous and exogenous control of ecosystem function: N cycling in headwater streams.  

PubMed

Allochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of 15N as nitrate in six streams differing in riparian-stream interaction and metabolic character. Nitrate removal was quantified using a nutrient spiraling approach based on measurements of downstream decline in 15N flux. Respiration (R) and gross primary production (GPP) were measured with whole-stream diel oxygen budgets. Uptake and metabolism metrics were addressed as z scores relative to site means to assess temporal variation. In open-canopied streams, areal uptake (U; microg N x m(-2) x s(-1)) was closely related to GPP, metabolic rates increased with temperature, and R was accurately predicted by metabolic scaling relationships. In forested streams, N spiraling was not related to GPP; instead, uptake velocity (v(f); mm/s) was closely related to R. In contrast to open-canopied streams, N uptake and metabolic activity were negatively correlated to temperature and poorly described by scaling laws. We contend that streams differ along a gradient of exogenous and endogenous control that relates to the relative influences of resource subsidies and in-stream energetics as determinants of seasonal patterns of metabolism and N cycling. Our research suggests that temporal variation in the propagation of ecological influence between adjacent systems generates phases when ecosystems are alternatively characterized as endogenously and exogenously controlled. PMID:19137956

Valett, H M; Thomas, S A; Mulholland, P J; Webster, J R; Dahm, C N; Fellows, C S; Crenshaw, C L; Peterson, C G

2008-12-01

193

Endogenous and exogenous control of ecosystem function: N cycling in headwater streams  

SciTech Connect

Allochthonous inputs act as resource subsidies to many ecosystems, where they exert strong influences on metabolism and material cycling. At the same time, metabolic theory proposes endogenous thermal control independent of resource supply. To address the relative importance of exogenous and endogenous influences, we quantified spatial and temporal variation in ecosystem metabolism and nitrogen (N) uptake using seasonal releases of {sup 15}N as nitrate in six streams differing in riparian-stream interaction and metabolic character. Nitrate removal was quantified using a nutrient spiraling approach based on measurements of downstream decline in {sup 15}N flux. Respiration (R) and gross primary production (GPP) were measured with whole-stream diel oxygen budgets. Uptake and metabolism metrics were addressed as z scores relative to site means to assess temporal variation. In open-canopied streams, areal uptake (U; {micro}g N {center_dot} m{sup -2} {center_dot} s{sup -1}) was closely related to GPP, metabolic rates increased with temperature, and R was accurately predicted by metabolic scaling relationships. In forested streams, N spiraling was not related to GPP; instead, uptake velocity (v{sub f}; mm/s) was closely related to R. In contrast to open-canopied streams, N uptake and metabolic activity were negatively correlated to temperature and poorly described by scaling laws. We contend that streams differ along a gradient of exogenous and endogenous control that relates to the relative influences of resource subsidies and in-stream energetics as determinants of seasonal patterns of metabolism and N cycling. Our research suggests that temporal variation in the propagation of ecological influence between adjacent systems generates phases when ecosystems are alternatively characterized as endogenously and exogenously controlled.

Mulholland, Patrick J [ORNL; Valett, H. Maurice [Virginia Polytechnic Institute and State University (Virginia Tech); Thomas, Steve [University of Nebraska; Webster, Jackson [Virginia Polytechnic Institute and State University (Virginia Tech); Dahm, Cliff [University of New Mexico, Albuquerque; Fellows, Christine [Griffith University, Nathan, Queensland, Australia; Crenshaw, Chelsea [University of New Mexico, Albuquerque; Peterson, Chris G. [Loyola University

2008-01-01

194

Old and New Stories: Revelations from Functional Analysis of the Bovine Mammary Transcriptome during the Lactation Cycle  

PubMed Central

The cow mammary transcriptome was explored at ?30, ?15, 1, 15, 30, 60, 120, 240, and 300 d relative to parturition. A total of 6,382 differentially expressed genes (DEG) at a false discovery rate ?0.001 were found throughout lactation. The greatest number of DEG (>3,500 DEG) was observed at 60 and 120 d vs. ?30 d with the largest change between consecutive time points observed at ?15 vs. 1 d and 120 vs. 240 d. Functional analysis of microarray data was performed using the Dynamic Impact Approach (DIA). The DIA analysis of KEGG pathways uncovered as the most impacted and induced ‘Galactose metabolism’, ‘Glycosylphosphatidylinositol (GPI)-anchor biosynthesis’, and ‘PPAR signaling’; whereas, ‘Antigen processing and presentation’ was among the most inhibited. The integrated interpretation of the results suggested an overall increase in metabolism during lactation, particularly synthesis of carbohydrates and lipid. A marked degree of utilization of amino acids as energy source, an increase of protein export, and a decrease of the protein synthesis machinery as well cell cycle also were suggested by the DIA analysis. The DIA analysis of Gene Ontology and other databases uncovered an induction of Golgi apparatus and angiogenesis, and the inhibition of both immune cell activity/migration and chromosome modifications during lactation. All of the highly-impacted and activated functions during lactation were evidently activated at the onset of lactation and inhibited when milk production declined. The overall analysis indicated that the bovine mammary gland relies heavily on a coordinated transcriptional regulation to begin and end lactation. The functional analysis using DIA underscored the importance of genes associated with lactose synthesis, lipid metabolism, protein synthesis, Golgi, transport, cell cycle/death, epigenetic regulation, angiogenesis, and immune function during lactation. PMID:22428004

Bionaz, Massimo; Periasamy, Kathiravan; Rodriguez-Zas, Sandra L.; Everts, Robin E.; Lewin, Harris A.; Hurley, Walter L.; Loor, Juan J.

2012-01-01

195

Dosage-Sensitive Function of RETINOBLASTOMA RELATED and Convergent Epigenetic Control Are Required during the Arabidopsis Life Cycle  

PubMed Central

The plant life cycle alternates between two distinct multi-cellular generations, the reduced gametophytes and the dominant sporophyte. Little is known about how generation-specific cell fate, differentiation, and development are controlled by the core regulators of the cell cycle. In Arabidopsis, RETINOBLASTOMA RELATED (RBR), an evolutionarily ancient cell cycle regulator, controls cell proliferation, differentiation, and regulation of a subset of Polycomb Repressive Complex 2 (PRC2) genes and METHYLTRANSFERASE 1 (MET1) in the male and female gametophytes, as well as cell fate establishment in the male gametophyte. Here we demonstrate that RBR is also essential for cell fate determination in the female gametophyte, as revealed by loss of cell-specific marker expression in all the gametophytic cells that lack RBR. Maintenance of genome integrity also requires RBR, because diploid plants heterozygous for rbr (rbr/RBR) produce an abnormal portion of triploid offspring, likely due to gametic genome duplication. While the sporophyte of the diploid mutant plants phenocopied wild type due to the haplosufficiency of RBR, genetic analysis of tetraploid plants triplex for rbr (rbr/rbr/rbr/RBR) revealed that RBR has a dosage-dependent pleiotropic effect on sporophytic development, trichome differentiation, and regulation of PRC2 subunit genes CURLY LEAF (CLF) and VERNALIZATION 2 (VRN2), and MET1 in leaves. There were, however, no obvious cell cycle and cell proliferation defects in these plant tissues, suggesting that a single functional RBR copy in tetraploids is capable of maintaining normal cell division but is not sufficient for distinct differentiation and developmental processes. Conversely, in leaves of mutants in sporophytic PRC2 subunits, trichome differentiation was also affected and expression of RBR and MET1 was reduced, providing evidence for a RBR-PRC2-MET1 regulatory feedback loop involved in sporophyte development. Together, dosage-sensitive RBR function and its genetic interaction with PRC2 genes and MET1 must have been recruited during plant evolution to control distinct generation-specific cell fate, differentiation, and development. PMID:20585548

Johnston, Amal J.; Kirioukhova, Olga; Barrell, Philippa J.; Rutten, Twan; Moore, James M.; Baskar, Ramamurthy; Grossniklaus, Ueli; Gruissem, Wilhelm

2010-01-01

196

Functional electrical stimulation cycling improves body composition, metabolic and neural factors in persons  

E-print Network

was used to assess motor and sensory function. An oral glucose tolerance (OGTT) and insulin- response test) are at a heightened risk of developing type II diabetes and cardiovascular disease. The purpose of this investigation-ray absorptiometry. The American Spinal Injury Association (ASIA) neu- rological classification of SCI test battery

Griffin, Lisa

197

An N-Myristoylated Globin with a Redox-Sensing Function That Regulates the Defecation Cycle in Caenorhabditis elegans  

PubMed Central

Globins occur in all kingdoms of life where they fulfill a wide variety of functions. In the past they used to be primarily characterized as oxygen transport/storage proteins, but since the discovery of new members of the globin family like neuroglobin and cytoglobin, more diverse and complex functions have been assigned to this heterogeneous family. Here we propose a function for a membrane-bound globin of C. elegans, GLB-26. This globin was predicted to be myristoylated at its N-terminus, a post-translational modification only recently described in the globin family. In vivo, this globin is found in the membrane of the head mesodermal cell and in the tail stomato-intestinal and anal depressor muscle cells. Since GLB-26 is almost directly oxidized when exposed to oxygen, we postulate a possible function as electron transfer protein. Phenotypical studies show that GLB-26 takes part in regulating the length of the defecation cycle in C. elegans under oxidative stress conditions. PMID:23251335

Tilleman, Lesley; De Henau, Sasha; Pauwels, Martje; Nagy, Nora; Pintelon, Isabel; Braeckman, Bart P.; De Wael, Karolien; Van Doorslaer, Sabine; Adriaensen, Dirk; Timmermans, Jean-Pierre; Moens, Luc; Dewilde, Sylvia

2012-01-01

198

Some evidence on determinants of fuel economy as a function of driving cycle and test type  

SciTech Connect

Statistical methods are used with 107 vehicles whose fuel economy was presented and reported for five test types in a single publication by Consumers Union (CU) for 1986--1988 vehicles. Standard loglinear statistical formulations (i.e., multiplicative models of interactions) are used with data from this and supplementary sources to develop coefficients estimating the percent fuel economy gain per percent change in engine/vehicle design characteristic. The coefficients are developed for the five different test conditions evaluated by CU and are compared with each other on the basis of attributes of the tests. The insights of engineering models are used to develop expectations regarding the shift in size of coefficients as driving cycles change. In both the engineering models and the statistical model, the effect of weight is estimated to be higher in urban driving than in highway driving. For two test categories -- field tests and dynamometer tests -- the benefits of weight reduction are statistically estimated to be greatest in urban driving conditions. The effect on idle fuel flow rate of designing vehicles to hold performance roughly constant by maintaining power per kilogram and/or displacement per kilogram is examined, and its implication for the size of the weight effect is simply approximated from Sovran`s 1983 engineering model results. The fuel-economy-decreasing effect of the desire for performance is estimated to be somewhat larger in the statistical analysis than in the NAS study, when engine technology is held constant.

Santini, D.J.; Anderson, J.

1993-08-01

199

Study of nickel electrode oxidation as a function of 80% depth of discharge cycling  

SciTech Connect

Oxidation of nickel sinter used in nickel oxide electrodes in aerospace nickel cadmium cells leads to hydrogen gassing and the potential for cell rupture. The oxidation is directly related to loss of overcharge protection built into the cell during manufacturing. In nickel hydrogen cells, excessive oxidation of the nickel sinter can eventually lead to a burst before leak situation and is a potential source of failure. It is well known that nickel cadmium cells having nylon separators contribute to loss of overcharge via a hydrolysis reaction of the nylon in the potassium hydroxide electrolyte environment in the cell. The hydrolysis reaction produces lower chain organics which are oxidized by the positive electrode and oxygen. Oxidation of the organics diminishes the overcharge protection. With introduction of the Super NiCd{trademark} and the Magnum{trademark} nickel cadmium cells the nylon hydrolysis reaction is eliminated, but any reducing agent in the cell such as nickel or an organic additive can contribute to loss of overcharge protection. The present effort describes chemical analyses made to evaluate the extent of overcharge protection loss in nickel cadmium cells which do not have nylon hydrolysis, and quantifies the amount of hydrogen buildup in nickel hydrogen cells which are subjected to 80% depth of discharge cycling with and without the presence of cadmium in the positive electrode.

Pickett, D.F. Jr.; Scoles, D.L.; Johnson, Z.W.; Hayden, J.W.; Pennington, R.D. [Eagle-Picher Industries, Inc., Colorado Springs, CO (United States)

1997-12-31

200

Luteal blood flow is a more appropriate indicator for luteal function during the bovine estrous cycle than luteal size.  

PubMed

The objective of this study was to assess the reliability of luteal blood flow (LBF) as recorded by color Doppler sonography to monitor luteal function during the estrous cycle of dairy cows and to compare the results with that for the established criterion luteal size (LS) as determined by B-mode sonography. In total, 14 consecutive sonographic examinations were carried out in 10 synchronized lactating Holstein-Friesian cows (Bos taurus) on Days 4, 5, 6, 7, 8, 10, 12, 14, 16, -5, -4, -3, -2, -1 of the estrous cycle (Day 1=ovulation). Plasma progesterone concentrations in venous blood (P(4)) were quantified by enzyme immunoassay. Luteal size was determined by sonographic measurement of the maximal cross-sectional area of the corpus luteum (CL). Luteal blood supply was estimated by calculating the maximum colored area of the CL from power Doppler sonographic images. Luteal size doubled during the luteal growth phase (until Day 7) and remained at this level during the luteal static phase (Day 8 to 16) before decreasing rather slowly during luteal regression (Days -5 to -1). Luteal blood flow doubled during the growth phase, doubled furthermore during the static phase, and decreased rapidly during luteal regression. Thus, LBF values represented highly reliable predictors of luteal status. Luteal blood flow predicted reliably a P(4)>1.0 ng/mL by reaching only 35% of the maximal values, whereas LS had to exceed 60% of the maximal values to indicate reliably a functional CL. It is concluded that LBF reflected luteal function better than LS specifically during luteal regression. PMID:20071016

Herzog, K; Brockhan-Lüdemann, M; Kaske, M; Beindorff, N; Paul, V; Niemann, H; Bollwein, H

2010-03-15

201

Effect of Yoga on Autonomic Functions and Psychological Status During Both Phases of Menstrual Cycle in Young Healthy Females  

PubMed Central

Context: Premenstrual stress affects 75% of women of childbearing age and yoga has been found to be beneficial in many psycho-somatic disorders. Aims: To investigate the effect of integrated yoga on autonomic parameters and psychological well-being during both pre and post phases of menstrual cycle in healthy young female subjects. Settings and Design: Present study is a randomized control trial and was conducted in the Department of Physiology, Lady Hardinge Medical College, New Delhi, India. Material and Methods: Fifty apparently healthy females in the age group of 18-20 years were randomized into two groups: Group I (n=25) consisted of subjects who practiced yoga 35-40 minutes per day, six times per week for the duration of three menstrual cycles. Training was given by qualified yoga instructor. Group II (n=25) subjects acted as controls. Following parameters were recorded at the beginning and after completion of three menstrual cycles in all the subjects: Height, weight (BW), Resting Heart Rate (HR), Resting Systolic (SBP) and Diastolic Blood Pressure (DBP), parasympathetic reactivity tests including Expiration-Inspiration Ratio (E: I ratio) and 30:15 ratio, sympathetic reactivity tests including BP changes due to Isometric Hand Grip (IHG) exercise, and Cold Pressor Test (CPT). Assessment of psychological status was done by administering DIPAS (Defense Institute of Physiology and Allied Sciences) inventories of Anger self report scale, Trait Anxiety, Sense of well-being and Depression scale. Statistical Analysis: Intra-group comparison of physiological parameters was done by using paired ‘t’ test, whereas intra-group comparison of non-parameteric data such as scores of anxiety, depression, anger and sense of well-being was done by Wilcoxon signed-rank test. Inter-group comparison of parameters was done by Students ‘t’ test for parametric tests and Mann-Whitney ‘U’ test for non-parameteric tests. Results: There was significantly higher BW, resting SBP, DBP, sympathetic activity and blunting of parasympathetic reactivity and also, significantly higher scores of anger, depression, anxiety and decreased score of well-being in premenstrual phase as compared to postmenstrual phase in both the groups in initial cycle. There was significantly higher percentage decrease in BW, HR, SBP & DBP in yoga group as compared to control group in both the phases from initial to second and onwards between second and third menstrual cycle. Also, decrease in anger, depression and anxiety and increase in well-being score was significant in yoga group as compared to control group from initial to second and third cycle in premenstrual phase while the change was significant only in depression score in postmenstrual phase. Conclusion: Our study shows that there was significant alteration of autonomic functions and psychological status in premenstrual phase when compared with postmenstrual phase in young healthy females. Also, regular practice of yoga has beneficial effects on both phases of menstrual cycle by bringing parasympathodominance and psychological well-being probably by balancing neuro-endocrinal axis. PMID:24298457

Kanojia, Sarita; Sharma, Vivek Kumar; Gandhi, Asha; Kapoor, Raj; Kukreja, Ajay; Subramanian, Senthil Kumar

2013-01-01

202

Influence of functional unit on the life cycle assessment of traction batteries  

Microsoft Academic Search

Goal, Scope and Background  This paper describes the influence of the choice of the functional unit on the results of an environmental assessment of different\\u000a battery technologies for electric and hybrid vehicles. Battery, hybrid and fuel cell electric vehicles are considered as being\\u000a environmentally friendly. However, the batteries they use are sometimes said to be environmentally unfriendly. At the current\\u000a state

Julien Matheys; Wout Van Autenboer; Jean-Marc Timmermans; Joeri Van Mierlo; Peter Van den Bossche; Gaston Maggetto

2007-01-01

203

Liver X Receptor Agonists Augment Human Islet Function through Activation of Anaplerotic Pathways and Glycerolipid/Free Fatty Acid Cycling*  

PubMed Central

Recent studies in rodent models suggest that liver X receptors (LXRs) may play an important role in the maintenance of glucose homeostasis and islet function. To date, however, no studies have comprehensively examined the role of LXRs in human islet biology. Human islets were isolated from non-diabetic donors and incubated in the presence or absence of two synthetic LXR agonists, TO-901317 and GW3965, under conditions of low and high glucose. LXR agonist treatment enhanced both basal and stimulated insulin secretion, which corresponded to an increase in the expression of genes involved in anaplerosis and reverse cholesterol transport. Furthermore, enzyme activity of pyruvate carboxylase, a key regulator of pyruvate cycling and anaplerotic flux, was also increased. Whereas LXR agonist treatment up-regulated known downstream targets involved in lipogenesis, we observed no increase in the accumulation of intra-islet triglyceride at the dose of agonist used in our study. Moreover, LXR activation increased expression of the genes encoding hormone-sensitive lipase and adipose triglyceride lipase, two enzymes involved in lipolysis and glycerolipid/free fatty acid cycling. Chronically, insulin gene expression was increased after treatment with TO-901317, and this was accompanied by increased Pdx-1 nuclear protein levels and enhanced Pdx-1 binding to the insulin promoter. In conclusion, our data suggest that LXR agonists have a direct effect on the islet to augment insulin secretion and expression, actions that should be considered either as therapeutic or unintended side effects, as these agents are developed for clinical use. PMID:20007976

Ogihara, Takeshi; Chuang, Jen-Chieh; Vestermark, George L.; Garmey, James C.; Ketchum, Robert J.; Huang, Xiaolun; Brayman, Kenneth L.; Thorner, Michael O.; Repa, Joyce J.; Mirmira, Raghavendra G.; Evans-Molina, Carmella

2010-01-01

204

Mitochondrial dynamics, biogenesis, and function are coordinated with the cell cycle by APC/C CDH1.  

PubMed

Cell proliferation is associated with a high rate of aerobic glycolysis, which has been widely interpreted as a compensatory mechanism for suppressed mitochondrial function, despite reports of high respiration rates. The molecular mechanisms that link cell proliferation with mitochondrial metabolism, dynamics, and biogenesis remain obscure. Here, we show that proliferation is associated with an increase in both glycolysis and respiration, in conjunction with mitochondrial fusion and biogenesis. Changes in mitochondrial morphology and mass are due to accumulation of OPA1, MFN1, and TFAM, silencing any of which hinders cell proliferation. Moreover, the levels of OPA1, MFN1, and TFAM are regulated by the ubiquitin ligase APC/C(CDH1), which also controls proteasomal degradation of key glycolytic, glutaminolytic, and cell-cycle proteins. Thus, we have identified an important component of the molecular mechanism that coordinates cell proliferation with activation of the mitochondrial metabolic machinery that provides the necessary energy and biosynthetic substrates. PMID:22482729

Garedew, Assegid; Andreassi, Catia; Moncada, Salvador

2012-04-01

205

Functional Analysis of Centrosomal Kinase Substrates in Drosophila melanogaster Reveals a New Function of the Nuclear Envelope Component Otefin in Cell Cycle Progression  

PubMed Central

Phosphorylation is one of the key mechanisms that regulate centrosome biogenesis, spindle assembly, and cell cycle progression. However, little is known about centrosome-specific phosphorylation sites and their functional relevance. Here, we identified phosphoproteins of intact Drosophila melanogaster centrosomes and found previously unknown phosphorylation sites in known and unexpected centrosomal components. We functionally characterized phosphoproteins and integrated them into regulatory signaling networks with the 3 important mitotic kinases, cdc2, polo, and aur, as well as the kinase CkII?. Using a combinatorial RNA interference (RNAi) strategy, we demonstrated novel functions for P granule, nuclear envelope (NE), and nuclear proteins in centrosome duplication, maturation, and separation. Peptide microarrays confirmed phosphorylation of identified residues by centrosome-associated kinases. For a subset of phosphoproteins, we identified previously unknown centrosome and/or spindle localization via expression of tagged fusion proteins in Drosophila SL2 cells. Among those was otefin (Ote), an NE protein that we found to localize to centrosomes. Furthermore, we provide evidence that it is phosphorylated in vitro at threonine 63 (T63) through Aurora-A kinase. We propose that phosphorylation of this site plays a dual role in controlling mitotic exit when phosphorylated while dephosphorylation promotes G2/M transition in Drosophila SL2 cells. PMID:22751930

Habermann, Karin; Mirgorodskaya, Ekaterina; Gobom, Johan; Lehmann, Verena; Müller, Hannah; Blümlein, Katharina; Deery, Michael J.; Czogiel, Irina; Erdmann, Christoph; Ralser, Markus; von Kries, Jens Peter

2012-01-01

206

In situ Expression of Functional Genes Reveals Nitrogen Cycling at High Temperatures in Terrestrial Hydrothermal Systems  

NASA Astrophysics Data System (ADS)

An essential element for life, nitrogen occurs in all living organisms and is critical for the synthesis of amino acids, proteins, nucleic acids, and other forms of biomass. Thus, nitrogen cycling likely plays a vital role in microbial metabolic processes as well as nutrient availability. For microorganisms in "extreme" environments, this means developing adaptations that allow them to survive in harsh conditions and still perform the metabolisms essential to sustain life. Recent studies have screened biofilms and thermal sediments of Yellowstone National Park (YNP) thermal features for the presence of nifH genes, which code for a key enzyme in the nitrogen fixation process [1-4]. Furthermore, analysis of nitrogen isotopes in biofilms across a temperature and chemical gradient revealed that nitrogen fixation likely varies across the chemosynthetic/photosynthetic ecotone [5]. Although research has evaluated and confirmed the presence of nifH genes in various thermophilic microbial communities, the existence of a gene in the DNA of an organism does not verify its use. Instead, other methods, such as culturing, isotope tracer assays, and gene expression studies are required to provide direct evidence of biological nitrogen fixation. Culturing and isotope tracer approaches have successfully revealed high-temperature biological nitrogen fixation in both marine hydrothermal vent microbial communities [6] and in acidic, terrestrial hydrothermal sediment [3]. Transcriptomics-based techniques (using mRNA extracted from samples to confirm in situ expression of targeted genes) have been much more limited in number, and only a few studies have, to date, investigated in situ expression of the nifH gene in thermophilic microbial communities [2, 7]. This study explores the presence and expression of nifH genes in several features of the Lower Geyser Basin (LGB) of YNP. Nucleic acids from chemosynthetic and photosynthetic microbial communities were extracted and then amplified using (reverse-transcription) polymerase chain reaction to identify the presence and expression of nifH genes, and resultant (RT-)PCR product was cloned and sequenced. Results reveal high-temperature in situ expression of nifH in select LGB features [7] which is, to the authors' knowledge, the first direct evidence of nifH transcription in the chemosynthetic zones of terrestrial hydrothermal systems. Results also indicate the presence of novel nifH sequences and allow phylogenetic comparison of nifH genes along geochemical gradients within individual hot spring features and between various thermal features in the LGB. Collectively, these results provide evidence for microbial adaptations that have led to the ability to support basic metabolic processes under "extreme" conditions. [1] Hall et al., 2008. AEM 74: 4910-4922. [2] Steunou et al., 2008. The ISME Journal 2: 364-378. [3] Hamilton et al., 2011. Microb Ecol DOI 10.1007/s00248-011-9824-9. [4] Raymond et al., 2008. EOS Trans AGU. Abstract B14A-03. [5] Havig et al., 2010. J Geophys Res-Biogeo 116: G01005. [6] Mehta & Baross, 2006. Science 314: 1783-1786. [7] Loiacono et al., 2011. Submitted FEMS Microbiol Ecol.

Loiacono, S. T.; Meyer-Dombard, D. R.

2011-12-01

207

Usual dietary isoflavone intake and reproductive function across the menstrual cycle  

PubMed Central

Objective To assess the association of total isoflavone intake with ovulatory function, including sporadic anovulation in healthy premenopausal women. Design Prospective cohort study. Setting University. Patient(s) Participants included 259 healthy regularly menstruating women aged 18–44 years. Intervention(s) None. Main Outcome Measure(s) Serum concentrations of E2, free E2, P, LH, FSH, and SHBG and sporadic anovulation in healthy premenopausal women. Result(s) Isoflavone intake was not associated with E2, free E2, P, LH, and FSH concentrations. Consumption in the highest quartile (Q4: 1.6–78.8 mg/d) was significantly associated with greater SHBG concentrations (? = 0.09; 95% confidence interval [CI] 0.02–0.16), compared with the first quartile (Q1: 0.0–0.3 mg/d). Conclusion(s) Isoflavone intake was not associated with sporadic anovulation (Q4 vs. Q1: odds ratio 0.87, 95% CI 0.32–1.66). Dietary isoflavone intake among young premenopausal women was not related to sex hormone concentrations or anovulation, but was associated with minimally increased SHBG concentrations. These results suggest potential endocrine effects with no subsequent effects on ovulation, easing concerns regarding their impacts on fertility. PMID:23998910

Filiberto, Amanda C.; Mumford, Sunni L.; Pollack, Anna Z.; Zhang, Cuilin; Yeung, Edwina H.; Schliep, Karen C.; Perkins, Neil J.; Wactawski-Wende, Jean; Schisterman, Enrique F.

2013-01-01

208

Various players in the nitrogen cycle: Diversity and functions of the microorganisms involved in nitrification and denitrification  

Microsoft Academic Search

Microorganisms play important roles in the nitrogen cycles of various ecosystems. Research has revealed that a greater diversity of microorganisms is involved in the nitrogen cycle than previously understood. It is becoming clear that denitrifying fungi, nitrifying archaea, anammox bacteria, aerobic denitrifying bacteria and heterotrophic nitrifying microorganisms are key players in the nitrogen cycle. Studies have revealed a major contribution

Masahito Hayatsu; Kanako Tago; Masanori Saito

2008-01-01

209

Glutamate is the major anaplerotic substrate in the tricarboxylic acid cycle of isolated rumen epithelial and duodenal mucosal cells from beef cattle  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study aimed to determine the contribution of substrates to tricarboxylic acid (TCA) cycle fluxes in rumen epithelial (REC) and duodenal mucosal (DMC) cells isolated from bulls (n = 6) fed either a 75% forage (HF) or 75% concentrate (HC) diet. In separate incubations, [13C6]glucose, [13C5]glutam...

210

Biological weathering and the long-term carbon cycle: integrating mycorrhizal evolution and function into the current paradigm.  

PubMed

The dramatic decline in atmospheric CO2 evidenced by proxy data during the Devonian (416.0-359.2 Ma) and the gradual decline from the Cretaceous (145.5-65.5 Ma) onwards have been linked to the spread of deeply rooted trees and the rise of angiosperms, respectively. But this paradigm overlooks the coevolution of roots with the major groups of symbiotic fungal partners that have dominated terrestrial ecosystems throughout Earth history. The colonization of land by plants was coincident with the rise of arbuscular mycorrhizal fungi (AMF),while the Cenozoic (c. 65.5-0 Ma) witnessed the rise of ectomycorrhizal fungi (EMF) that associate with both gymnosperm and angiosperm tree roots. Here, we critically review evidence for the influence of AMF and EMF on mineral weathering processes. We show that the key weathering processes underpinning the current paradigm and ascribed to plants are actually driven by the combined activities of roots and mycorrhizal fungi. Fuelled by substantial amounts of recent photosynthate transported from shoots to roots, these fungi form extensive mycelial networks which extend into soil actively foraging for nutrients by altering minerals through the acidification of the immediate root environment. EMF aggressively weather minerals through the additional mechanism of releasing low molecular weight organic chelators. Rates of biotic weathering might therefore be more usefully conceptualized as being fundamentally controlled by the biomass, surface area of contact, and capacity of roots and their mycorrhizal fungal partners to interact physically and chemically with minerals. All of these activities are ultimately controlled by rates of carbon-energy supply from photosynthetic organisms. The weathering functions in leading carbon cycle models require experiments and field studies of evolutionary grades of plants with appropriate mycorrhizal associations. Representation of the coevolution of roots and fungi in geochemical carbon cycle models is required to further our understanding of the role of the biota in Earth's CO2 and climate history. PMID:19323695

Taylor, L L; Leake, J R; Quirk, J; Hardy, K; Banwart, S A; Beerling, D J

2009-03-01

211

Catabolite control protein E (CcpE) is a LysR-type transcriptional regulator of tricarboxylic acid cycle activity in Staphylococcus aureus.  

PubMed

The tricarboxylic acid cycle (TCA cycle) is a central metabolic pathway that provides energy, reducing potential, and biosynthetic intermediates. In Staphylococcus aureus, TCA cycle activity is controlled by several regulators (e.g. CcpA, CodY, and RpiRc) in response to the availability of sugars, amino acids, and environmental stress. Developing a bioinformatic search for additional carbon catabolite-responsive regulators in S. aureus, we identified a LysR-type regulator, catabolite control protein E (CcpE), with homology to the Bacillus subtilis CcpC regulator. Inactivation of ccpE in S. aureus strain Newman revealed that CcpE is a positive transcriptional effector of the first two enzymes of the TCA cycle, aconitase (citB) and to a lesser extent citrate synthase (citZ). Consistent with the transcriptional data, aconitase activity dramatically decreased in the ccpE mutant relative to the wild-type strain. The effect of ccpE inactivation on citB transcription and the lesser effect on citZ transcription were also reflected in electrophoretic mobility shift assays where CcpE bound to the citB promoter but not the citZ promoter. Metabolomic studies showed that inactivation of ccpE resulted in increased intracellular concentrations of acetate, citrate, lactate, and alanine, consistent with a redirection of carbon away from the TCA cycle. Taken together, our data suggest that CcpE is a major direct positive regulator of the TCA cycle gene citB. PMID:24194525

Hartmann, Torsten; Zhang, Bo; Baronian, Grégory; Schulthess, Bettina; Homerova, Dagmar; Grubmüller, Stephanie; Kutzner, Erika; Gaupp, Rosmarie; Bertram, Ralph; Powers, Robert; Eisenreich, Wolfgang; Kormanec, Jan; Herrmann, Mathias; Molle, Virginie; Somerville, Greg A; Bischoff, Markus

2013-12-13

212

Catabolite Control Protein E (CcpE) Is a LysR-type Transcriptional Regulator of Tricarboxylic Acid Cycle Activity in Staphylococcus aureus*  

PubMed Central

The tricarboxylic acid cycle (TCA cycle) is a central metabolic pathway that provides energy, reducing potential, and biosynthetic intermediates. In Staphylococcus aureus, TCA cycle activity is controlled by several regulators (e.g. CcpA, CodY, and RpiRc) in response to the availability of sugars, amino acids, and environmental stress. Developing a bioinformatic search for additional carbon catabolite-responsive regulators in S. aureus, we identified a LysR-type regulator, catabolite control protein E (CcpE), with homology to the Bacillus subtilis CcpC regulator. Inactivation of ccpE in S. aureus strain Newman revealed that CcpE is a positive transcriptional effector of the first two enzymes of the TCA cycle, aconitase (citB) and to a lesser extent citrate synthase (citZ). Consistent with the transcriptional data, aconitase activity dramatically decreased in the ccpE mutant relative to the wild-type strain. The effect of ccpE inactivation on citB transcription and the lesser effect on citZ transcription were also reflected in electrophoretic mobility shift assays where CcpE bound to the citB promoter but not the citZ promoter. Metabolomic studies showed that inactivation of ccpE resulted in increased intracellular concentrations of acetate, citrate, lactate, and alanine, consistent with a redirection of carbon away from the TCA cycle. Taken together, our data suggest that CcpE is a major direct positive regulator of the TCA cycle gene citB. PMID:24194525

Hartmann, Torsten; Zhang, Bo; Baronian, Grégory; Schulthess, Bettina; Homerova, Dagmar; Grubmüller, Stephanie; Kutzner, Erika; Gaupp, Rosmarie; Bertram, Ralph; Powers, Robert; Eisenreich, Wolfgang; Kormanec, Jan; Herrmann, Mathias; Molle, Virginie; Somerville, Greg A.; Bischoff, Markus

2013-01-01

213

Small RNA-dependent Expression of Secondary Metabolism Is Controlled by Krebs Cycle Function in Pseudomonas fluorescens*  

PubMed Central

Pseudomonas fluorescens CHA0, an antagonist of phytopathogenic fungi in the rhizosphere of crop plants, elaborates and excretes several secondary metabolites with antibiotic properties. Their synthesis depends on three small RNAs (RsmX, RsmY, and RsmZ), whose expression is positively controlled by the GacS-GacA two-component system at high cell population densities. To find regulatory links between primary and secondary metabolism in P. fluorescens and in the related species Pseudomonas aeruginosa, we searched for null mutations that affected central carbon metabolism as well as the expression of rsmY-gfp and rsmZ-gfp reporter constructs but without slowing down the growth rate in rich media. Mutation in the pycAB genes (for pyruvate carboxylase) led to down-regulation of rsmXYZ and secondary metabolism, whereas mutation in fumA (for a fumarase isoenzyme) resulted in up-regulation of the three small RNAs and secondary metabolism in the absence of detectable nutrient limitation. These effects required the GacS sensor kinase but not the accessory sensors RetS and LadS. An analysis of intracellular metabolites in P. fluorescens revealed a strong positive correlation between small RNA expression and the pools of 2-oxoglutarate, succinate, and fumarate. We conclude that Krebs cycle intermediates (already known to control GacA-dependent virulence factors in P. aeruginosa) exert a critical trigger function in secondary metabolism via the expression of GacA-dependent small RNAs. PMID:19840935

Takeuchi, Kasumi; Kiefer, Patrick; Reimmann, Cornelia; Keel, Christoph; Dubuis, Christophe; Rolli, Joëlle; Vorholt, Julia A.; Haas, Dieter

2009-01-01

214

Effect of Chronic Renal Failure on Cardiac Contractile Function, Calcium Cycling, and Gene Expression of Proteins Important for Calcium Homeostasis in the Rat  

Microsoft Academic Search

Patients with chronic renal failure frequently develop cardiac hypertrophy and diastolic dysfunction; however, the mechanisms by which this occurs are still unclear. Male Sprague-Dawley rats were subjected to 5\\/6 nephrectomy and studied for their isolated myocyte function, calcium cycling, and gene expression of proteins important in calcium ho- meostasis after 4 wk. Comparable rats subjected to suprarenal aortic banding for

DAVID KENNEDY; EIAD OMRAN; SANKARIDRUG M. PERIYASAMY; JAMES C. WILLEY; DEEPAK MALHOTRA; ZIJIAN XIE; JOSEPH I. SHAPIRO

2003-01-01

215

Combined effects of CO2 enrichment and elevated growth temperatures on metabolites in soybean leaflets; evidence for dynamic changes of TCA cycle intermediates  

Technology Transfer Automated Retrieval System (TEKTRAN)

Soybean (Glycine max [Merr.]L.) was grown in indoor chambers with ambient (38 Pa) and elevated (70 Pa) CO2 and day/night temperature treatments of 28/20, 32/24, and 36/28 °C. Net rates of CO2 assimilation increased with growth temperature and were enhanced an additional 25% on average by CO2 enrich...

216

Diurnal Changes in Mitochondrial Function Reveal Daily Optimization of Light and Dark Respiratory Metabolism in Arabidopsis*  

PubMed Central

Biomass production by plants is often negatively correlated with respiratory rate, but the value of this rate changes dramatically during diurnal cycles, and hence, biomass is the cumulative result of complex environment-dependent metabolic processes. Mitochondria in photosynthetic plant tissues undertake substantially different metabolic roles during light and dark periods that are dictated by substrate availability and the functional capacity of mitochondria defined by their protein composition. We surveyed the heterogeneity of the mitochondrial proteome and its function during a typical night and day cycle in Arabidopsis shoots. This used a staged, quantitative analysis of the proteome across 10 time points covering 24 h of the life of 3-week-old Arabidopsis shoots grown under 12-h dark and 12-h light conditions. Detailed analysis of enzyme capacities and substrate-dependent respiratory processes of isolated mitochondria were also undertaken during the same time course. Together these data reveal a range of dynamic changes in mitochondrial capacity and uncover day- and night-enhanced protein components. Clear diurnal changes were evident in mitochondrial capacities to drive the TCA cycle and to undertake functions associated with nitrogen and sulfur metabolism, redox poise, and mitochondrial antioxidant defense. These data quantify the nature and nuances of a daily rhythm in Arabidopsis mitochondrial respiratory capacity. PMID:20601493

Lee, Chun Pong; Eubel, Holger; Millar, A. Harvey

2010-01-01

217

Analysis of the Prevalence, Secretion and Function of a Cell Cycle-Inhibiting Factor in the Melioidosis Pathogen Burkholderia pseudomallei  

PubMed Central

Enteropathogenic and enterohaemorrhagic Escherichia coli express a cell cycle-inhibiting factor (Cif), that is injected into host cells via a Type III secretion system (T3SS) leading to arrest of cell division, delayed apoptosis and cytoskeletal rearrangements. A homologue of Cif has been identified in Burkholderia pseudomallei (CHBP; Cif homologue in B. pseudomallei; BPSS1385), which shares catalytic activity, but its prevalence, secretion and function are ill-defined. Among 43 available B. pseudomallei genome sequences, 33 genomes (76.7%) harbor the gene encoding CHBP. Western blot analysis using antiserum raised to a synthetic CHBP peptide detected CHBP in 46.6% (7/15) of clinical B. pseudomallei isolates from the endemic area. Secretion of CHBP into bacterial culture supernatant could not be detected under conditions where a known effector (BopE) was secreted in a manner dependent on the Bsa T3SS. In contrast, CHBP could be detected in U937 cells infected with B. pseudomallei by immunofluorescence microscopy and Western blotting in a manner dependent on bsaQ. Unlike E. coli Cif, CHBP was localized within the cytoplasm of B. pseudomallei-infected cells. A B. pseudomallei chbP insertion mutant showed a significant reduction in cytotoxicity and plaque formation compared to the wild-type strain that could be restored by plasmid-mediated trans-complementation. However, there was no defect in actin-based motility or multinucleated giant cell formation by the chbP mutant. The data suggest that the level or timing of CHBP secretion differs from a known Bsa-secreted effector and that CHBP is required for selected virulence-associated phenotypes in vitro. PMID:24809950

Pumirat, Pornpan; Broek, Charles Vander; Juntawieng, Niramol; Muangsombut, Veerachat; Kiratisin, Pattarachai; Pattanapanyasat, Kovit; Stevens, Joanne M.; Stevens, Mark P.; Korbsrisate, Sunee

2014-01-01

218

Cloning and functional characterization of Ptpcd2 as a novel cell cycle related protein tyrosine phosphatase that regulates mitotic exit.  

PubMed

Faithful transmission of genetic information depends on accurate chromosome segregation as cells exit from mitosis, and errors in chromosomal segregation are catastrophic and may lead to aneuploidy which is the hallmark of cancer. In eukaryotes, an elaborate molecular control system ensures proper orchestration of events at mitotic exit. Phosphorylation of specific tyrosyl residues is a major control mechanism for cellular proliferation and the activities of protein tyrosine kinases and phosphatases must be integrated. Although mitotic kinases are well characterized, phosphatases involved in mitosis remain largely elusive. Here we identify a novel variant of mouse protein tyrosine phosphatase containing domain 1 (Ptpcd1), that we named Ptpcd2. Ptpcd1 is a Cdc14 related centrosomal phosphatase. Our newly identified Ptpcd2 shared a significant homology to yeast Cdc14p (34.1%) and other Cdc14 family of phosphatases. By subcellular fractionation Ptpcd2 was found to be enriched in the cytoplasm and nuclear pellets with catalytic phosphatase activity. By means of immunofluorescence, Ptpcd2 was spatiotemporally regulated in a cell cycle dependent manner with cytoplasmic abundance during mitosis, followed by nuclear localization during interphase. Overexpression of Ptpcd2 induced mitotic exit with decreased levels of some mitotic markers. Moreover, Ptpcd2 failed to colocalize with the centrosomal marker ?-tubulin, suggesting it as a non-centrosomal protein. Taken together, Ptpcd2 phosphatase appears a non-centrosomal variant of Ptpcd1 with probable mitotic functions. The identification of this new phosphatase suggests the existence of an interacting phosphatase network that controls mammalian mitosis and provides new drug targets for anticancer modalities. PMID:23886163

Zineldeen, Doaa H; Wagih, Ayman A; Nakanishi, Makoto

2013-01-01

219

NUCLEAR FUNCTIONS OF ADENOMATOUS POLYPOSIS COLI: REGULATION OF THE G2-M CELL CYCLE TRANSITION & INTERMEDIATE FILAMENT INTERACTION  

E-print Network

Mutations in Adenomatous Polyposis Coli (APC) initiate most colorectal cancers. APC is implicated in regulating cell cycle and the cytoskeleton. I identified topoisomerase IIalpha (topo IIalpha), a regulator of G2 decatenation checkpoint, in complex...

Wang, Yang

2009-01-22

220

Inhibition of akt phosphorylation diminishes mitochondrial biogenesis regulators, tricarboxylic acid cycle activity and exacerbates recognition memory deficit in rat model of Alzheimer's disease.  

PubMed

3-Methyladenine (3-MA), as a PI3K inhibitor, is widely used for inhibition of autophagy. Inhibition of PI3K class I leads to inhibition of Akt phosphorylation, a central molecule involved in diverse arrays of intracellular cascades in nervous system. Accordingly, in the present study, we aimed to determine the alterations of specific mitochondrial biogenesis markers and mitochondrial function in 3-MA-injected rats following amyloid beta (A?) insult. Our data revealed that inhibition of Akt phosphorylation downregulates master regulator of mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1?). Our data also showed that decrease in PGC-1? level presumably is due to decrease in the phosphorylation of cAMP-response element binding and AMP-activated kinase, two upstream activators of PGC-1?. As a consequence, the level of some mitochondrial biogenesis factors including nuclear respiratory factor-1, mitochondrial transcription factor A, and Cytochrome c decreased significantly. Also, activities of tricarboxylic acid cycle (TCA) enzymes such as Aconitase, a-ketoglutarate dehydrogenase, and malate dehydrogenase reduced in the presence of 3-MA with or without A? insult. Decrease in mitochondrial biogenesis factors and TCA enzyme activity in the rats receiving 3-MA and A? were more compared to the rats that received either alone; indicating the additive destructive effects of these two agents. In agreement with our molecular results, data obtained from behavioral test (using novel objective recognition test) indicated that inhibition of Akt phosphorylation with or without A? injection impaired novel recognition (non-spatial) memory. Our results suggest that 3-MA amplified deleterious effects of A? by targeting central molecule Akt. PMID:25135709

Shaerzadeh, Fatemeh; Motamedi, Fereshteh; Khodagholi, Fariba

2014-11-01

221

Linking sediment structure, hydrological functioning and biogeochemical cycling in disturbed coastal saltmarshes and implications for vegetation development  

NASA Astrophysics Data System (ADS)

Saltmarsh restoration undoubtedly provides environmental enhancement, with vegetation quickly re-establishing following the breach of sea walls and subsequent tidal inundation of previously defended areas. Yet evidence increasingly suggests that the restored saltmarshes do not have the same biological characteristics as their natural counterparts (Mossman et al. 2012) and this may be in part be due to physicochemical parameters at the site including anoxia and poor drainage. Hence, restored saltmarshes may not offer the range and quality of ecosystem services anticipated. These environments will have been 'disturbed' by previous land use and there is little understanding of the impacts of this disturbance on the wider hydrogeomorphic and biogeochemical functioning in restored saltmarshes and the implications for saltmarsh vegetation development. This study examines linkages between physical sediment characteristics, sediment structure (using X-ray microtomography), sub-surface hydrology (using pressure transducers and time series analysis), and sediment and porewater geochemistry (major and trace elements, major anions) in sediment cores collected from undisturbed saltmarshes and those restored by de-embankment. Sub-surface sediments in restored saltmarshes have lower organic matter content, lower moisture content and higher bulk density than undisturbed sites. Using X-ray tomography a clear horizon can be observed which separates relict agricultural soils at depth with less dense and structureless sediments deposited since de-embankment. Ratios of open to closed pore space suggest that while undisturbed saltmarshes have the highest porosity, restored saltmarshes have larger void spaces, but limited pore connectivity. Sub-surface hydrological response to tidal flooding was subdued in the restored compared to the undisturbed site, suggesting that porewater flow may be impeded. Time series analysis indicated that flow pathways differ in restored saltmarsh sediments with preferential horizontal flows. The undisturbed saltmarsh displayed typical vertical geochemical sediment profiles. However, in the restored sites total Fe and Mn are elevated at depth indicating an absence of diagenetic cycling, whilst porewater sulphate and nitrate increased at depth suggesting that vertical solute transport is impeded in restored sites. In surface sediments, though total Hg concentrations are similar, Hg methylation rates are significantly higher than in the undisturbed saltmarsh suggesting that surface anoxia and poor drainage may result in increased mobilization and bioavailability of Hg. These findings have implications for the wider biogeochemical ecosystem services offered by saltmarsh restoration and the water-logged, anoxic conditions produced are unsuitable for seedling germination and plant growth. This highlights the need for integrated understanding of physical and biogeochemical processes.

Spencer, Kate; Harvey, Gemma; James, Tempest; Simon, Carr; Michelle, Morris

2014-05-01

222

Cassia tora L. (Jue-ming-zi) has anticancer activity in TCA8113 cells in vitro and exerts anti-metastatic effects in vivo  

PubMed Central

Cassia tora L. (Jue-ming-zi) is a traditional Chinese medicine widely used in East Asia. The in vitro anticancer effects of Jue-ming-zi were evaluated in TCA8113 human tongue carcinoma cells using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. At a concentration of 1.0 mg/ml, Cassia tora L. inhibited the growth of TCA8113 cells by 72%; this inhibiton was greater than that by 0.5 and 0.25 mg/ml Cassia tora L. (43 and 16%, respectively). To elucidate the inhibitory mechanisms underlying the anticancer effect of Cassia tora L. in cancer cells, the expression of genes associated with apoptosis, inflammation and metastasis were measured using RT-PCR and western blot analysis. Cassia tora L. significantly induced apoptosis in cancer cells (P<0.05) by upregulating Bax, caspase-3 and caspase-9, and by downregulating Bcl-2. The expression of genes associated with inflammation, including NF-?B, iNOS and COX-2, was significantly downregulated (P<0.05) by Cassia tora L., demonstrating its anti-inflammatory properties. Cassia tora L. also exerted a significant anti-metastatic effect on cancer cells as demonstrated by decreased mRNA expression of matrix metalloprotease (MMP) genes and increased expression of tissue inhibitors of metalloproteinases (TIMPs), and as confirmed by the inhibition of induced tumor metastasis induced in 26-M3.1 colon cells in BALB/c mice. Our results demonstrated that Cassia tora L. exhibited the most potent in vitro anticancer effects, induced apoptosis, had anti-inflammatory activities and exerted in vivo anti-metastatic effects. Additionally, the anticancer, anti-inflammatory and anti-metastatic effects of the higher Cassia tora L. concentrations were stronger compared with those of the lower Cassia tora L. concentrations tested. PMID:23426077

ZHAO, XIN; WANG, QIANG; QIAN, YU; PANG, LIANG

2013-01-01

223

Raf1 Physically Interacts with Rb and Regulates Its Function: a Link between Mitogenic Signaling and Cell Cycle Regulation  

Microsoft Academic Search

Cells initiate proliferation in response to growth factor stimulation, but the biochemical mechanisms linking signals received at the cell surface receptors to the cell cycle regulatory molecules are not yet clear. In this study, we show that the signaling molecule Raf-1 can physically interact with Rb and p130 proteins in vitro and in vivo and that this interaction can be

SHENG WANG; RICHIK N. GHOSH; SRIKUMAR P. CHELLAPPAN

1998-01-01

224

Regulation of the Structure and Function of the Light Harvesting Complexes of Photosystem II by the Xanthophyll Cycle  

Microsoft Academic Search

The xanthophyll cycle is a relatively simple process whereby the interconversion of violaxanthin into zeaxanthin in the light harvesting complexes serves to regulate light harvesting and subsequent energy dissipation in different light environments. In order to determine how these carotenoids can regulate such processes it is first important to ascertain what differences exist between these two xanthophylls. Deepoxidation brings about

Peter Horton; Alexander V. Ruban; Andrew J. Young

225

Predicting VO[subscript 2max] in College-Aged Participants Using Cycle Ergometry and Perceived Functional Ability  

ERIC Educational Resources Information Center

The purpose of this study was to develop a multiple linear regression model to predict treadmill VO[subscript 2max] scores using both exercise and non-exercise data. One hundred five college-aged participants (53 male, 52 female) successfully completed a submaximal cycle ergometer test and a maximal graded exercise test on a motorized treadmill.…

Nielson, David E.; George, James D.; Vehrs, Pat R.; Hager, Ron L.; Webb, Carrie V.

2010-01-01

226

Tubulin heterodimers remain functional for one cell cycle after the inactivation of tubulin-folding cofactor D in fission yeast cells.  

PubMed

Tubulin-folding cofactor D plays a major role in the formation of functional tubulin heterodimers, the subunits of microtubules (MTs) that are essential for cell division. Previous work has suggested that, in Schizosaccharomyces pombe, cofactor D function is required during G(1) or S phases of the cell cycle, and when it fails to function due to the temperature-sensitive mutation alp1-t1, cells are unable to segregate their chromosomes in the subsequent mitosis. Here we report that another mutation in the cofactor D gene, alp1-1315, causes failures in either the first or second mitosis in cells synchronized in G(1) or G(2) phases, respectively. Other results, however, suggest that the kinetics of viability loss in these mutants does not depend on progression through the cell cycle. When cofactor D function is perturbed in cells blocked in G(2), cytoplasmic MTs appear normal for 2-3 h but thereafter they disintegrate quickly, so that only a few short MTs remain. These residual MTs are, however, stably maintained, suggesting that they do not require active cofactor D function. The abrupt disassembly of MT cytoskeleton at restrictive temperature in non-cycling cofactor D mutant cells strongly suggests that the life-span of folded tubulin dimers might be downregulated. Indeed, this period is significantly shorter than the previously determined dissociation time of bovine tubulins in vitro. The death of mutant cells occurs inevitably after 2-3 h at restrictive temperature in the following mitosis, and is explained by the idea that MT structures formed in the absence of cofactor D cannot support normal cell division. PMID:19330768

Fedyanina, Olga S; Book, Adam J; Grishchuk, Ekaterina L

2009-04-01

227

Carbon and nitrogen cycling in thermally heated sediments  

NASA Astrophysics Data System (ADS)

Hydrothermally heated sediment environments, such as are found in abundance throughout Yellowstone National Park, host fully functional microbial ecosystems. As with any ecosystem, both sources and sinks of carbon, nitrogen, and a myriad of other nutrients and energy-driving factors must be supplied. While we know microbial communities in hydrothermal environments can be surprisingly diverse, we know little about basic ecological functions such as carbon and nitrogen cycling. Previous work has shown that carbon cycling in one hot spring in Yellowstone National Park [“Bison Pool”] and its associated runoff channel functions as a complex system. Analysis of carbon and nitrogen isotopes in sediments and biofilms across a temperature and chemical gradient at this location revealed that the four best studied carbon fixation pathways [Calvin, reverse tricarboxylic acid, acetyl-CoA, 3-hydroxypropionate cycles] may all be functioning in this system, and nitrogen fixation varies across the chemosynthetic/photosynthetic ecotone [1]. Microcosm experiments using biofilms from this hot spring as inoculae with 13C labeled carbon substrates indicate heterotrophic growth [2]. In addition, metagenomic analysis of environmental DNA has indicated the presence of genes involved in carbon fixation [both phototrophic and autotrophic], and heterotrophy, as well as nitrogen fixation [3]. Studies from other Yellowstone locations have also found genetic evidence for carbon and nitrogen fixation [4, 5]. Of particular interest is the role of individuals in carbon and nitrogen cycling as environmental conditions suitable for chemosynthetic and photosynthetic growth vary. This study explores the diversity of cbbM/cbbL [Calvin cycle], aclB/oor/porA [rTCA cycle], nifH [nitrogen fixation], nirK [nitrite reduction] and amoA [ammonia oxidation] genes across a variety of Yellowstone environments. The transition of genetic diversity within sediments and biofilms is focused on the chemosynthetic/photosynthetic ecotone from a variety of hot springs spanning a range of pH and geochemical conditions. By sampling across this ecotone, changes in carbon and nitrogen fixation as a function of changing community structure become apparent. Environmental DNA was extracted from these samples, and the presence/absence of Bacteria and Archaea determined by PCR. In addition, PCR-directed screens reveal the presence or absence of the aforementioned functional genes. Further, comparison across a broad spectrum of environmental conditions supplies context for phylogenetic analysis of diversity. [1] Havig, J.R., 2009. Geochemistry of Hydrothermal Biofilms: Composition of Biofilms in Siliceous Sinter-Deposting Hot Springs. Doctoral Dissertation, Arizona State University. [2] Meyer-Dombard et al., 2007. Microbial Diversity and SIP Investigations of Streamer Biofilm Communities in Yellowstone. Goldschmidt Geochemical Conference. [3] Raymond et al., 2008. EOS Trans AGU. Abstract B14A-03. [4] Hall et al., 2008. AEM 74:4910-4922. [5] Steunou et al., 2006. PNAS 103:2398-2403.

Meyer-Dombard, D. R.; Burton, M.; Vennelakanti, S.; Havig, J. R.; Shock, E.

2009-12-01

228

Performance improvement of GaN-based metal-semiconductor-metal photodiodes grown on Si(111) substrate by thermal cycle annealing process  

NASA Astrophysics Data System (ADS)

A simple thermal cycle annealing (TCA) process was used to improve the quality of GaN grown on a Si substrate. The X-ray diffraction (XRD) and etch pit density (EPD) results revealed that using more process cycles, the defect density cannot be further reduced. However, the performance of GaN-based metal-semiconductor-metal (MSM) photodiodes (PDs) prepared on Si substrates showed significant improvement. With a two-cycle TCA process, it is found that the dark current of the device was only 1.46 × 10-11 A, and the photo-to-dark-current contrast ratio was about 1.33 × 105 at 5 V. Also, the UV/visible rejection ratios can reach as high as 1077.

Lin, Jyun-Hao; Huang, Shyh-Jer; Su, Yan-Kuin

2014-01-01

229

The effects of sensorial denervation on the ovarian function, by the local administration of capsaicin, depend on the day of the oestrous cycle when the treatment was performed.  

PubMed

There is evidence that sensory innervation plays a role in the regulation of puberty. The present study investigates the effects of functional sensorial desensitisation induced by capsaicin administration to adult female rats in the days of diestrus 1, diestrus 2, pro-oestrus or oestrus on ovulation and serum oestradiol and progesterone concentration. The animals were allotted at random to one of the following groups: (1) animals with capsaicin administration into the bursa ovarica (local administration) (2) animals with vehicle administration into the bursa ovarica and (3) untreated animals group. The animals treated were killed on the day of oestrus after three consecutive 4-day oestrous cycles. No differences were observed in oestrous cyclicity or the average number of ova shed between the sensorial desensitisation animals and the vehicle-treated groups. Capsaicin administration resulted in a significant increase in the intra-ovarian noradrenaline levels in the day of diestrus 2 and pro-oestrus. Serum oestradiol and progesterone concentrations were different, depending on the day of the oestrous cycle in which the treatment was performed. These results suggest that in adult normal female rats, ovarian sensorial innervations participate together with the sympathetic innervation in the ovarian function regulating the hormone secretion and this participation varies along the oestrous cycle. PMID:24861475

Trujillo, Angélica; Morales, Leticia; Domínguez, Roberto

2015-02-01

230

Changes in Sleep Time and Sleep Quality across the Ovulatory Cycle as a Function of Fertility and Partner Attractiveness  

PubMed Central

Research suggests that near ovulation women tend to consume fewer calories and engage in more physical activity; they are judged to be more attractive, express greater preferences for masculine and symmetrical men, and experience increases in sexual desire for men other than their primary partners. Some of these cycle phase shifts are moderated by partner attractiveness and interpreted as strategic responses to women's current reproductive context. The present study investigated changes in sleep across the ovulatory cycle, based on the hypothesis that changes in sleep may reflect ancestral strategic shifts of time and energy toward reproductive activities. Participants completed a 32-day daily diary in which they recorded their sleep time and quality for each day, yielding over 1,000 observations of sleep time and quality. Results indicated that, when the probability of conception was high, women partnered with less attractive men slept more, while women with more attractive partners slept less. PMID:24710508

Goetz, Aaron T.

2014-01-01

231

Method based on GC-MS to study the influence of tricarboxylic acid cycle metabolites on cardiovascular risk factors.  

PubMed

Metabolites involved in the tricarboxylic acid (TCA) cycle have previously been proposed as cardiovascular biomarkers. This cycle plays a key role in cell metabolism and the levels of the involved metabolites can also be affected by other physiological factors. The influence of three cardiovascular risk factors such as obesity, hypercholesterolemia, and smoking habit on serum levels of TCA-cycle metabolites has been studied in patients diagnosed with significant coronary lesion. For this purpose, a method based on GC-MS for determination of the target metabolites (viz. citric/isocitric, pyruvic, aconitic, oxaloacetic, malic, fumaric and succinic acids) in serum has been developed. The high accuracy and throughput analysis featuring the method have allowed application to a cohort of 223 patients, 172 of them with significant coronary lesion. Multifactor analysis of variance has revealed interactions between the occurrence or not of a coronary lesion and the risk factors considered in this study. These interactions were crucial to explain the levels of target TCA metabolites. Statistical evaluation by ROC curves allowed discrimination of the capability of significant metabolites with the occurrence of coronary lesions. PMID:23245249

Calderón-Santiago, M; Priego-Capote, F; Galache-Osuna, J G; Luque de Castro, M D

2013-02-23

232

The importance of a highly active and DeltapH-regulated diatoxanthin epoxidase for the regulation of the PS II antenna function in diadinoxanthin cycle containing algae.  

PubMed

The present study focuses on the regulation of diatoxanthin (Dtx) epoxidation in the diadinoxanthin (Ddx) cycle containing algae Phaeodactylum tricornutum, Thalassiosira pseudonana, Cyclotella meneghiniana and Prymnesium parvum and its significance for the control of the photosystem II (PS II) antenna function. Our data show that Dtx epoxidase can exhibit extremely high activities when algal cells are transferred from high light (HL) to low light (LL). Under HL conditions, Dtx epoxidation is strongly inhibited by the light-driven proton gradient. Uncoupling of the cells during HL illumination restores the high epoxidation rates observed during LL. In Ddx cycle containing algae, non-photochemical quenching of chlorophyll fluorescence (NPQ) is directly correlated with the Dtx concentration and independent of the presence of the proton gradient. This means that a fast conversion of PS II from the heat dissipating state back to the light-harvesting state can only be realized by an efficient removal of the quenching pigment Dtx. It is proposed that the high Dtx epoxidation rates during LL illumination serve exactly this purpose. The inhibition of Dtx epoxidation by the DeltapH, on the other hand, ensures rapid increases in the Dtx concentration when photoprotection under conditions of HL illumination is required. The regulation of the PS II antenna function in Ddx cycle containing algae is different to that in violaxanthin (Vx) cycle containing plants, where for the zeaxanthin (Zx)-dependent NPQ the presence of a proton gradient is mandatory. In the green alga Chlorella vulgaris conversion of PS II from the heat dissipating state back to the light-harvesting state is controlled by the DeltapH, whose relaxation after a transition from HL to darkness or LL rapidly abolishes the thermal dissipation of excitation energy, including the Zx-dependent NPQ. Due to the inability of Zx to quench fluorescence in the absence of the DeltapH a fast epoxidation of Zx to Vx in LL is not needed and is missing in Chlorella vulgaris. PMID:16971213

Goss, Reimund; Ann Pinto, Elizabeth; Wilhelm, Christian; Richter, Michael

2006-10-01

233

Geodetic data inversion using ABIC to estimate slip history during one earthquake cycle with viscoelastic slip-response functions  

NASA Astrophysics Data System (ADS)

We developed a new method of geodetic data inversion to estimate slip history at a plate interface by using Akaike's Bayesian Information Criterion (ABIC). In this method we considered the effects of viscoelastic stress relaxation in the asthenosphere, which cannot be neglected to estimate slip history at a plate interface during one earthquake cycle. We also introduced a proper formulation to incorporate two sorts of partially dependent prior information into observed data by Bayes' rule. By applying the new inversion method to levelling data for 1893-1983 in Shikoku, southwestern Japan, we reconstructed the pattern of space-time variation in slip motion during one earthquake cycle, including the 1946 Nankai earthquake, at the interface between the Eurasian and the Philippine Sea plates. The result shows that a steady slip motion at a plate convergence rate (40 mm yr-1) proceeds in the shallow and the deep regions through the entire earthquake cycle. In the intermediate depth range (10-30 km), on the other hand, an instantaneous slip of approximately 4 m occurs at the time of the Nankai earthquake. After that, this portion keeps in stationary contact until the occurrence of the next Nankai earthquake. If we neglect the effects of viscoelastic stress relaxation, the inversion analysis gives geophysically unrealistic results.

Fukahata, Yukitoshi; Nishitani, Akira; Matsu'ura, Mitsuhiro

2004-01-01

234

Rock Cycle: Cycling  

NSDL National Science Digital Library

This Science Object is the third of four Science Objects in the Rocks SciPack. It explores the variables that contribute to rock transformation and the continuous processes of rock formation that constitute the rock cycle. The rock cycle provides an example of the transfer of energy and mass in the Earth system. Earth is a closed system containing essentially a fixed amount of each element. Movement of matter is driven by the Earth's internal and external sources of energy, and is often accompanied by changes in the physical and chemical properties of the matter. Minerals are made, dissolved, and remade--on the Earth's surface, in the oceans, and in the hot, high-pressure layers beneath the crust. The total amount of material stays the same as its forms change. Learning Outcomes:? Recognize the formation and transformation processes as part of a continuing cycle.? Identify that while the form and location of different rocks change over time, the amount of material and the distribution among the elements remains constant.? Explain the different processes or paths that each type of rock may take in the rock cycle.

National Science Teachers Association (NSTA)

2006-11-01

235

Succession of microbial functional communities in response to a pilot-scale ethanol-blended fuel release throughout the plume life cycle.  

PubMed

GeoChip, a comprehensive gene microarray, was used to examine changes in microbial functional gene structure throughout the 4-year life cycle of a pilot-scale ethanol blend plume, including 2-year continuous released followed by plume disappearance after source removal. Canonical correlation analysis (CCA) and Mantel tests showed that dissolved O2 (which was depleted within 5 days of initiating the release and rebounded 194 days after source removal) was the most influential environmental factor on community structure. Initially, the abundance of anaerobic BTEX degradation genes increased significantly while that of aerobic BTEX degradation genes decreased. Gene abundance for N fixation, nitrification, P utilization, sulfate reduction and S oxidation also increased, potentially changing associated biogeochemical cycle dynamics. After plume disappearance, most genes returned to pre-release abundance levels, but the final functional structure significantly differed from pre-release conditions. Overall, observed successions of functional structure reflected adaptive responses that were conducive to biodegradation of ethanol-blend releases. PMID:25603154

Ma, Jie; Deng, Ye; Yuan, Tong; Zhou, Jizhong; Alvarez, Pedro J J

2015-03-01

236

Trichloroacetic acid cycling in Sitka spruce (Picea sitchensis) saplings and the effects on tree health following long term exposure.   

E-print Network

Trichloroacetic acid (TCA, CCl3COOH) has been associated with forest damage but the source of TCA to trees is poorly characterised. To investigate the routes and effects of TCA uptake in conifers, 120 Sitka spruce (Picea ...

Dickey, Catherine A; Heal, Kate V; Stidson, R T; Koren, R; Cape, Neil; Schröder, V; Heal, Mathew R

2004-01-01

237

Plant functional group removal alters root biomass and nutrient cycling in a typical steppe in Inner Mongolia, China  

Microsoft Academic Search

Loss of functional diversity has been demonstrated to have a variety of impacts on ecosystem functioning. However, most studies\\u000a have been implemented in artificially assembled communities by removing the original vegetation and seeding with desired species\\u000a or functional group compositions. Such approaches could significantly disturb belowground biomass, especially roots, making\\u000a it difficult to examine belowground responses to diversity manipulations. To

Deliang Kong; Huifang Wu; Hui Zeng; Xiaotao Lü; Matthew Simmons; Meng Wang; Xiaofang Sun; Xingguo Han

238

Solar activity secular cycles  

NASA Astrophysics Data System (ADS)

Long-term variations in solar activity secular cycles have been studied using a method for the expansion of reconstructed sunspot number series Sn( t) for 11400 years in terms of natural orthogonal functions. It has been established that three expansion components describe more than 98% of all Sn( t) variations. In this case, the contribution of the first expansion component is about 92%. The averaged form of the 88year secular cycle has been determined based on the form of the first expansion coordinate function. The quasi-periodicities modulating the secular cycle have been revealed based on the time function conjugate to the first function. The quasi-periodicities modulating the secular cycle coincide with those observed in the Sn( t) series spectrum. A change in the secular cycle form and the time variations in this form are described by the second and third expansion components, the contributions of which are about 4 and 2%, respectively. The variations in the steepness of the secular cycle branches are more pronounced in the 200-year cycle, and the secular cycle amplitude varies more evidently in the 2300-year cycle.

Kramynin, A. P.; Mordvinov, A. V.

2013-12-01

239

Sometimes "Newton's Method" Always "Cycles"  

ERIC Educational Resources Information Center

Are there functions for which Newton's method cycles for all non-trivial initial guesses? We construct and solve a differential equation whose solution is a real-valued function that two-cycles under Newton iteration. Higher-order cycles of Newton's method iterates are explored in the complex plane using complex powers of "x." We find a class of…

Latulippe, Joe; Switkes, Jennifer

2012-01-01

240

Global Analysis of Host Cell Gene Expression Late during Cytomegalovirus Infection Reveals Extensive Dysregulation of Cell Cycle Gene Expression and Induction of Pseudomitosis Independent of US28 Function  

PubMed Central

Replication of human cytomegalovirus (CMV) depends on host cell gene products working in conjunction with viral functions and leads to a dramatic dysregulation of cell cycle gene expression. Comprehensive transcriptional profiling was used to identify pathways most dramatically modulated by CMV at late times during infection and to determine the extent to which expression of the viral chemokine receptor US28 contributed to modulating cellular gene expression. Cells infected with the AD169 strain of virus or a fully replication competent US28-deficient derivative (RV101) were profiled throughout the late phase of infection (50, 72, and 98 h postinfection). Although sensitive statistical analysis showed striking global changes in transcript levels in infected cells compared to uninfected cells, the expression of US28 did not contribute to these alterations. CMV infection resulted in lower levels of transcripts encoding cytoskeletal, extracellular matrix, and adhesion proteins, together with small GTPases and apoptosis regulators, and in higher levels of transcripts encoding cell cycle, DNA replication, energy production, and inflammation-related gene products. Surprisingly, a large number of cellular transcripts encoding mitosis-related proteins were upmodulated at late times in infection, and these were associated with the formation of abnormal mitotic spindles and the appearance of pseudomitotic cells. These data extend our understanding of how broadly CMV alters the regulation of host cell cycle gene products and highlight the establishment of a mitosis-like environment in the absence of cellular DNA replication as important for viral replication and maturation. PMID:15479839

Hertel, Laura; Mocarski, Edward S.

2004-01-01

241

SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH A SOLAR CYCLE  

E-print Network

SOLAR WIND HELIUM ABUNDANCE AS A FUNCTION OF SPEED AND HELIOGRAPHIC LATITUDE: VARIATION THROUGH of the variation of the relative abundance of helium to hydrogen in the solar wind as a function of solar wind that for solar wind speeds between 350 and 415 km sÀ1 , AHe varies with a clear 6 month periodicity

Richardson, John

242

Developmental regulation of mitochondrial biogenesis and function in the mouse mammary gland during a prolonged lactation cycle  

Technology Transfer Automated Retrieval System (TEKTRAN)

The regulation of mitochondrial biogenesis and function in the lactating mammary cell is poorly understood. The goal of this study was to use proteomics to relate temporal changes in mammary cell mitochondrial function during lactation to changes in the proteins that make up this organelle. The hypo...

243

Proteome-based comparative analyses of growth stages reveal new cell cycle-dependent functions in the predatory bacterium Bdellovibrio bacteriovorus.  

PubMed

Bdellovibrio and like organisms are obligate predators of bacteria that are ubiquitously found in the environment. Most exhibit a peculiar dimorphic life cycle during which free-swimming attack-phase (AP) cells search for and invade bacterial prey cells. The invader develops in the prey as a filamentous polynucleoid-containing cell that finally splits into progeny cells. Therapeutic and biocontrol applications of Bdellovibrio in human and animal health and plant health, respectively, have been proposed, but more knowledge of this peculiar cell cycle is needed to develop such applications. A proteomic approach was applied to study cell cycle-dependent expression of the Bdellovibrio bacteriovorus proteome in synchronous cultures of a facultative host-independent (HI) strain able to grow in the absence of prey. Results from two-dimensional gel electrophoresis, mass spectrometry, and temporal expression of selected genes in predicted operons were analyzed. In total, about 21% of the in silico predicted proteome was covered. One hundred ninety-six proteins were identified, including 63 hitherto unknown proteins and 140 life stage-dependent spots. Of those, 47 were differentially expressed, including chemotaxis, attachment, growth- and replication-related, cell wall, and regulatory proteins. Novel cell cycle-dependent adhesion, gliding, mechanosensing, signaling, and hydrolytic functions were assigned. The HI model was further studied by comparing HI and wild-type AP cells, revealing that proteins involved in DNA replication and signaling were deregulated in the former. A complementary analysis of the secreted proteome identified 59 polypeptides, including cell contact proteins and hydrolytic enzymes specific to predatory bacteria. PMID:18836011

Dori-Bachash, Mally; Dassa, Bareket; Pietrokovski, Shmuel; Jurkevitch, Edouard

2008-12-01

244

Hirschsprung's disease: functional and psychological follow up comparing total colonic and rectosigmoid aganglionosis  

PubMed Central

Aims: To compare the long term functional and psychosocial outcomes following surgical treatment for total colonic aganglionosis (TCA) with those in an age and gender matched group of patients with rectosigmoid aganglionosis (RSA). Methods: Fifteen patients with TCA matched for age and gender with 15 patients with RSA were studied 7–17 years after the definitive operation. The internal and external sphincters were examined using anal endosonography. Functional outcome (faecal continence) was assessed by a surgeon not involved in the patients' care, and by a research psychologist in separate assessment sessions. The behavioural and emotional status of the patients was also assessed. Results: Based on the surgeon's assessment, 6/15 TCA and 7/15 RSA patients were continent. In comparison, based on the psychological interview, 2/15 TCA and 6/15 RSA patients were continent. The TCA patients reported significantly more behavioural/emotional problems and lower levels of self esteem than the RSA patients. The parent and teacher assessments of psychosocial status revealed no differences between the groups. There was no association between incontinence and psychosocial adjustment in either group. There was no association between the assessments of functional outcome and the endosonographic appearance of the anal sphincters. Conclusions: The proportion of patients with faecal incontinence 7–17 years after definitive surgery was high in both groups, but no association was found between incontinence and the psychosocial outcome measures. TCA patients perceived themselves as less well adjusted than their matched pairs. Differences between the groups in length of hospitalisation and severity of illness, especially in infancy and early childhood, may account for these differences. PMID:11970929

Ludman, L; Spitz, L; Tsuji, H; Pierro, A

2002-01-01

245

How do migratory species stay healthy over the annual cycle? A conceptual model for immune function and for resistance to disease.  

PubMed

Migration has fascinated researchers for years and many active areas of study exist. However, the question of how migratory species stay healthy within the context of their annual cycle remains relatively unexplored. This article addresses this question using Red Knots (Calidris canutus) as a model migrant species. We review recent research on immune function in Red Knots and integrate this work with the broader eco-immunological literature to introduce a conceptual model. This model synthesizes earlier ideas about resource allocation and the costs of immunity with recent increases in our knowledge about the vertebrate immune system and then puts these concepts into the context of defense against real pathogens in environments where a myriad of factors change in time and space. We also suggest avenues for further research, which will help to test the model and better link measures of immune function to pressure from pathogens and to optimal defense against disease. PMID:21558209

Buehler, Deborah M; Tieleman, B Irene; Piersma, Theunis

2010-09-01

246

Cytological cycles and fates in Psidium myrtoides are altered towards new cell metabolism and functionalities by the galling activity of Nothotrioza myrtoidis.  

PubMed

The morphogenesis of galls occurs by the redifferentiation of cells that assume new functions in the modified host plant organs. The redifferentiated cells in the galls of Nothotrioza myrtoidis on Psidium myrtoides have low complexity metabolism and are photosynthesis-deficient. These galls were studied in search for evidences of the establishment of new cell cycles and fates and cytological gradients that corroborate their metabolic profile. Young and mature leaves of P. myrtoides and leaf galls induced by N. myrtoidis at different developmental stages were collected along 24 months and analyzed under light and transmission electron microscopy. The leaves of P. myrtoides are long-lasting and did not senesce within the analyzed period, while the galls have a shorter cycle, and senesce within 1 year. A homogenous parenchyma is established by a "standby-redifferentiation" of the chlorophyllous tissues, and sclerenchyma cells redifferentiate from parenchyma cells in the outer cortex of the mature galls. The lack of organelles, the underdeveloped lamellation of chloroplasts, and the occurrence of few plastoglobules are related to the photosynthetic deficiency of the galls. No cytological gradients were observed, but the organelle-rich cells of the vascular and perivascular parenchymas are similar to those of the nutritive tissues of galls induced by other insect taxa. These cells nearest to the feeding sites of N. myrtoidis present higher metabolism and well-developed apparatus for the prevention of oxidative stress. The features herein described corroborate the low metabolic profile of the galls as the cell cycles and fates of P. myrtoides are manipulated for completely new functionalities. PMID:25272990

Carneiro, R G S; Isaias, R M S

2015-03-01

247

A Genetic Screen for Dominant Enhancers of the Cell-Cycle Regulator ?-Endosulfine Identifies Matrimony as a Strong Functional Interactor in Drosophila  

PubMed Central

The coordination of cell-cycle events with developmental processes is essential for the reproductive success of organisms. In Drosophila melanogaster, meiosis is tightly coupled to oocyte development, and early embryos undergo specialized S-M mitoses that are supported by maternal products. We previously showed that the small phosphoprotein ?-endosulfine (Endos) is required for normal oocyte meiotic maturation and early embryonic mitoses in Drosophila. In this study, we performed a genetic screen for dominant enhancers of endos00003 and identified several genomic regions that, when deleted, lead to impaired fertility of endos00003/+ heterozygous females. We uncovered matrimony (mtrm), which encodes a Polo kinase inhibitor, as a strong dominant enhancer of endos. mtrm126 +/+ endos00003 females are sterile because of defects in early embryonic mitoses, and this phenotype is reverted by removal of one copy of polo. These results provide compelling genetic evidence that excessive Polo activity underlies the strong functional interaction between endos00003 and mtrm126. Moreover, we show that endos is required for the increased expression of Mtrm in mature oocytes, which is presumably loaded into early embryos. These data are consistent with the model that maternal endos antagonizes Polo function in the early embryo to ensure normal mitoses through its effects on Mtrm expression during late oogenesis. Finally, we also identified genomic deletions that lead to loss of viability of endos00003/+ heterozygotes, consistent with recently published studies showing that endos is required zygotically to regulate the cell cycle during development. PMID:22384372

Von Stetina, Jessica R.; LaFever, Kimberly S.; Rubin, Mayer; Drummond-Barbosa, Daniela

2011-01-01

248

Code Calibration Applied to the TCA High-Lift Model in the 14 x 22 Wind Tunnel (Simulation With and Without Model Post-Mount)  

NASA Technical Reports Server (NTRS)

The objective of this study is to calibrate a Navier-Stokes code for the TCA (30/10) baseline configuration (partial span leading edge flaps were deflected at 30 degs. and all the trailing edge flaps were deflected at 10 degs). The computational results for several angles of attack are compared with experimental force, moments, and surface pressures. The code used in this study is CFL3D; mesh sequencing and multi-grid were used to full advantage to accelerate convergence. A multi-grid approach was used similar to that used for the Reference H configuration allowing point-to-point matching across all the trailingedge block interfaces. From past experiences with the Reference H (ie, good force, moment, and pressure comparisons were obtained), it was assumed that the mounting system would produce small effects; hence, it was not initially modeled. However, comparisons of lower surface pressures indicated the post mount significantly influenced the lower surface pressures, so the post geometry was inserted into the existing grid using Chimera (overset grids).

Lessard, Wendy B.

1999-01-01

249

Water Cycle  

NSDL National Science Digital Library

4th Grade Science - Water Cycle Water Cycle two day interactive lesson plan. DAY 1: Welcome to the Water Cycle! Today we are going to be exploring and finding out more about the wonderful Water Cycle! For starters we are going to start with a movie, click the following link and watch the video and ...

Mrs. Staley

2009-11-09

250

Carbon Cycles  

NSDL National Science Digital Library

Students are introduced to the concept of energy cycles by learning about the carbon cycle. They learn how carbon atoms travel through the geological (ancient) carbon cycle and the biological/physical carbon cycle. They consider how human activities disturb the carbon cycle by emitting carbon dioxide into the atmosphere. They discuss how engineers and scientists are working to reduce carbon dioxide emissions. Lastly, students consider how they can help the world through simple energy conservation measures.

2014-09-18

251

Decrease in Manganese Superoxide Dismutase Leads to Reduced Root Growth and Affects Tricarboxylic Acid Cycle Flux and Mitochondrial Redox Homeostasis1[C][W  

PubMed Central

Superoxide dismutases (SODs) are key components of the plant antioxidant defense system. While plastidic and cytosolic isoforms have been extensively studied, the importance of mitochondrial SOD at a cellular and whole-plant level has not been established. To address this, transgenic Arabidopsis (Arabidopsis thaliana) plants were generated in which expression of AtMSD1, encoding the mitochondrial manganese (Mn)SOD, was suppressed by antisense. The strongest antisense line showed retarded root growth even under control growth conditions. There was evidence for a specific disturbance of mitochondrial redox homeostasis in seedlings grown in liquid culture: a mitochondrially targeted redox-sensitive green fluorescent protein was significantly more oxidized in the MnSOD-antisense background. In contrast, there was no substantial change in oxidation of cytosolically targeted redox-sensitive green fluorescent protein, nor changes in antioxidant defense components. The consequences of altered mitochondrial redox status of seedlings were subtle with no widespread increase of mitochondrial protein carbonyls or inhibition of mitochondrial respiratory complexes. However, there were specific inhibitions of tricarboxylic acid (TCA) cycle enzymes (aconitase and isocitrate dehydrogenase) and an inhibition of TCA cycle flux in isolated mitochondria. Nevertheless, total respiratory CO2 output of seedlings was not decreased, suggesting that the inhibited TCA cycle enzymes can be bypassed. In older, soil-grown plants, redox perturbation was more pronounced with changes in the amount and/or redox poise of ascorbate and glutathione. Overall, the results demonstrate that reduced MnSOD affects mitochondrial redox balance and plant growth. The data also highlight the flexibility of plant metabolism with TCA cycle inhibition having little effect on overall respiratory rates. PMID:18337490

Morgan, Megan J.; Lehmann, Martin; Schwarzländer, Markus; Baxter, Charles J.; Sienkiewicz-Porzucek, Agata; Williams, Thomas C.R.; Schauer, Nicolas; Fernie, Alisdair R.; Fricker, Mark D.; Ratcliffe, R. George; Sweetlove, Lee J.; Finkemeier, Iris

2008-01-01

252

Decreased glycolytic and tricarboxylic acid cycle intermediates coincide with peripheral nervous system oxidative stress in a murine model of type 2 diabetes  

PubMed Central

Diabetic neuropathy (DN) is the most common complication of diabetes and is characterized by distal-to-proximal loss of peripheral nerve axons. The idea of tissue-specific pathological alterations in energy metabolism in diabetic complications-prone tissues is emerging. Altered nerve metabolism in type 1 diabetes models is observed; however, therapeutic strategies based on these models offer limited efficacy to type 2 diabetic patients with DN. Therefore, understanding how peripheral nerves metabolically adapt to the unique type 2 diabetic environment is critical to develop disease-modifying treatments. In the current study, we utilized targeted LC/MS/MS to characterize the glycolytic and tricarboxylic acid (TCA) cycle metabolomes in sural nerve, sciatic nerve and dorsal root ganglia (DRG) from male type 2 diabetic mice (BKS.Cg-m+/+Leprdb; db/db) and controls (db/+). We report depletion of glycolytic intermediates in diabetic sural nerve and sciatic nerve (glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-bisphosphate (sural nerve only), 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate, lactate), with no significant changes in DRG. Citrate and isocitrate TCA cycle intermediates were decreased in sural nerve, sciatic nerve and DRG from diabetic mice. Utilizing LC/ESI/MS/MS and HPLC methods, we also observed increased protein and lipid oxidation (nitrotyrosine; hydroxyoctadecadienoic acids, HODEs) in db/db tissue, with a proximal-to-distal increase in oxidative stress, with associated decreased aconitase enzyme activity. We propose a preliminary model, whereby the greater change in metabolomic profile, increase in oxidative stress, and decrease in TCA cycle enzyme activity may cause distal peripheral nerve to rely on truncated TCA cycle metabolism in the type 2 diabetes environment. PMID:23086140

Hinder, Lucy M.; Vivekanandan-Giri, Anuradha; McLean, Lisa L.; Pennathur, Subramaniam; Feldman, Eva L.

2013-01-01

253

Postsynthetic acetylation of histones during the cell cycle: a general function for the displacement of histones during chromatin rearrangements.  

PubMed

Postsynthetic acetylation of core histones exhibits a peak during S-phase of the Physarum cell cycle. The maximum 3H-acetate incorporation precedes the maximum of histone synthesis. Acetate is incorporated into all core histones during S-phase, but only into H2A and H2B during G2-period. Resolution of acetylated H4-subspecies reveals acetate incorporation into preexisting H4, but not into newly synthesized molecules during mitosis and early S-phase. In a protamine competition assay histones from S-phase chromatin are released at lower protamine concentrations as compared to the lower acetylated G2-chromatin. We demonstrate a preferential release of highly acetylated H4-subspecies at low protamine concentrations. Our results fit into a general model of the relationship between histone acetylation and chromatin assembly. According to this model acetylation of core histones would serve as a signal for displacement of histones from nucleosomes by modulating histone-protein or histone-DNA interactions. We propose that this mechanism operates during DNA-replication and transcription, as well as during other chromatin rearrangements. PMID:3118335

Loidl, P; Gröbner, P

1987-10-26

254

Mechanistic insights and functional determinants of the transport cycle of the ascorbic acid transporter SVCT2. Activation by sodium and absolute dependence on bivalent cations.  

PubMed

We characterized the human Na(+)-ascorbic acid transporter SVCT2 and developed a basic model for the transport cycle that challenges the current view that it functions as a Na(+)-dependent transporter. The properties of SVCT2 are modulated by Ca(2+)/Mg(2+) and a reciprocal functional interaction between Na(+) and ascorbic acid that defines the substrate binding order and the transport stoichiometry. Na(+) increased the ascorbic acid transport rate in a cooperative manner, decreasing the transport K(m) without affecting the V(max), thus converting a low affinity form of the transporter into a high affinity transporter. Inversely, ascorbic acid affected in a bimodal and concentration-dependent manner the Na(+) cooperativity, with absence of cooperativity at low and high ascorbic acid concentrations. Our data are consistent with a transport cycle characterized by a Na(+):ascorbic acid stoichiometry of 2:1 and a substrate binding order of the type Na(+):ascorbic acid:Na(+). However, SVCT2 is not electrogenic. SVCT2 showed an absolute requirement for Ca(2+)/Mg(2+) for function, with both cations switching the transporter from an inactive into an active conformation by increasing the transport V(max) without affecting the transport K(m) or the Na(+) cooperativity. Our data indicate that SVCT2 may switch between a number of states with characteristic properties, including an inactive conformation in the absence of Ca(2+)/Mg(2+). At least three active states can be envisioned, including a low affinity conformation at Na(+) concentrations below 20 mM and two high affinity conformations at elevated Na(+) concentrations whose Na(+) cooperativity is modulated by ascorbic acid. Thus, SVCT2 is a Ca(2+)/Mg(2+)-dependent transporter. PMID:17012227

Godoy, Alejandro; Ormazabal, Valeska; Moraga-Cid, Gustavo; Zúñiga, Felipe A; Sotomayor, Paula; Barra, Valeria; Vasquez, Osmán; Montecinos, Viviana; Mardones, Lorena; Guzmán, Catherine; Villagrán, Marcelo; Aguayo, Luis G; Oñate, Sergio A; Reyes, Alejandro M; Cárcamo, Juan G; Rivas, Coralia I; Vera, Juan Carlos

2007-01-01

255

Gene expression profiles in the bovine corpus luteum (CL) during the estrous cycle and pregnancy: Possible roles of chemokines in regulating CL function during pregnancy.  

PubMed

To determine functional differences between the corpus luteum (CL) of the estrous cycle and pregnancy in cows, gene expression profiles were compared using a 15 K bovine oligo DNA microarray. In the pregnant CL at days 20-25, 40-45 and 150-160, the expressions of 138, 265 and 455 genes differed by a factor of > 2-fold (P < 0.05) from their expressions in the cyclic CL (days 10-12 of the estrous cycle). Messenger RNA expressions of chemokines (eotaxin, lymphotactin and ENA-78) and their receptors (CCR3, XCR1 and CXCR2) were validated by quantitative real-time PCR. Transcripts of eotaxin were more abundant in the CL at days 40-45 and 150-160 of pregnancy than in the cyclic CL (P < 0.01). In contrast, the mRNA expressions of lymphotactin, ENA-78 and XCR1 were lower in the CL of pregnancy (P < 0.05). Messenger RNAs of CCR3 and CXCR2 were similarly detected both in the cyclic and pregnant CL. Tissue protein levels of eotaxin were significantly higher in the CL at days 150-160 of pregnancy than in the CL at other stages, whereas the lymphotactin protein levels in the CL at days 20-25 of pregnancy were lower (P < 0.05). Immunohistochemical staining showed that CCR3 was expressed in the luteal cells and that XCR1 was expressed in both the luteal cells and endothelial cells. Collectively, the different gene expression profiles may contribute to functional differences between the cyclic and pregnant CL, and chemokines including eotaxin and lymphotactin may regulate CL function during pregnancy in cows. PMID:25382605

Sakumoto, Ryosuke; Hayashi, Ken-Go; Hosoe, Misa; Iga, Kosuke; Kizaki, Keiichiro; Okuda, Kiyoshi

2015-02-24

256

Gene expression profiles in the bovine corpus luteum (CL) during the estrous cycle and pregnancy: Possible roles of chemokines in regulating CL function during pregnancy  

PubMed Central

To determine functional differences between the corpus luteum (CL) of the estrous cycle and pregnancy in cows, gene expression profiles were compared using a 15 K bovine oligo DNA microarray. In the pregnant CL at days 20–25, 40–45 and 150–160, the expressions of 138, 265 and 455 genes differed by a factor of > 2-fold (P < 0.05) from their expressions in the cyclic CL (days 10–12 of the estrous cycle). Messenger RNA expressions of chemokines (eotaxin, lymphotactin and ENA-78) and their receptors (CCR3, XCR1 and CXCR2) were validated by quantitative real-time PCR. Transcripts of eotaxin were more abundant in the CL at days 40–45 and 150–160 of pregnancy than in the cyclic CL (P < 0.01). In contrast, the mRNA expressions of lymphotactin, ENA-78 and XCR1 were lower in the CL of pregnancy (P < 0.05). Messenger RNAs of CCR3 and CXCR2 were similarly detected both in the cyclic and pregnant CL. Tissue protein levels of eotaxin were significantly higher in the CL at days 150–160 of pregnancy than in the CL at other stages, whereas the lymphotactin protein levels in the CL at days 20–25 of pregnancy were lower (P < 0.05). Immunohistochemical staining showed that CCR3 was expressed in the luteal cells and that XCR1 was expressed in both the luteal cells and endothelial cells. Collectively, the different gene expression profiles may contribute to functional differences between the cyclic and pregnant CL, and chemokines including eotaxin and lymphotactin may regulate CL function during pregnancy in cows. PMID:25382605

SAKUMOTO, Ryosuke; HAYASHI, Ken-Go; HOSOE, Misa; IGA, Kosuke; KIZAKI, Keiichiro; OKUDA, Kiyoshi

2014-01-01

257

Discover the Solar Cycle  

NSDL National Science Digital Library

This is an activity about the periodicity of the solar cycle. Learners will calculate the number of M-class solar flares as a percentage of the total number of X-ray solar flares and graph these results as a function of time. When compared to a graph of the number of sunspots as a function of time, learners make conclusions about the period of the solar cycle. This activity uses data from the Geostationary Operational Environmental Satellite (GOES).

2012-08-03

258

Methanol to olefin Conversion on HSAPO-34 zeolite from periodic density functional theory calculations: a complete cycle of side chain hydrocarbon pool mechanism  

SciTech Connect

For its unique position in the coal chemical industry, the methanol to olefin (MTO) reaction has been a hot topic in zeolite catalysis. Due to the complexities of catalyst structure and reaction networks, many questions such as how the olefin chain is built from methanol remain elusive. On the basis of periodic density functional theory calculations, this work establishes the first complete catalytic cycle for MTO reaction via hexamethylbenzene (HMB) trapped in HSAPO-34 zeolite based on the so-called side chain hydrocarbon pool mechanism. The cycle starts from the methylation of HMB that leads to heptamethylbenzenium ion (heptaMB{sup +}) intermediate. This is then followed by the growth of side chain via repeated deprotonation of benzenium ions and methylation of the exocyclic double bond. Ethene and propene can finally be released from the side ethyl and isopropyl groups of benzenium ions by deprotonation and subsequent protonation steps. We demonstrate that (i) HMB/HSAPO-34 only yields propene as the primary product based on the side chain hydrocarbon pool mechanism and (ii) an indirect proton-shift step mediated by water that is always available in the system is energetically more favorable than the traditionally regarded internal hydrogen-shift step. Finally, the implications of our results toward understanding the effect of acidity of zeolite on MTO activity are also discussed.

Wang, C.M.; Wang, Y.D.; Xie, Z.K.; Liu, Z.P. [SINOPEC, Shanghai (China)

2009-03-15

259

Restoration of mechanical and energetic function in failing aortic-banded rat hearts by gene transfer of calcium cycling proteins  

Microsoft Academic Search

The aim of this study was to examine whether short- and long-term gene transfer of Ca2+ handling proteins restore left ventricular (LV) mechanoenergetics in aortic banding-induced failing hearts. Aortic-banded rats received recombinant adenoviruses carrying sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) (Banding+SERCA), parvalbumin (Banding+Parv) or ?-galactosidase (Banding+?gal), or an adeno-associated virus carrying SERCA2a (Banding+AAV.SERCA) by a catheter-based technique. LV mechanoenergetic function was measured

Susumu Sakata; Djamel Lebeche; Naoya Sakata; Yuri Sakata; Elie R. Chemaly; Li Fan Liang; Tsuyoshi Tsuji; Yoshiaki Takewa; Federica del Monte; Richard Peluso; Krisztina Zsebo; Dongtak Jeong; Woo Jin Park; Yoshiaki Kawase; Roger J. Hajjar

2007-01-01

260

Deletion of human tarbp2 reveals cellular microRNA targets and cell-cycle function of TRBP.  

PubMed

TRBP functions as both a Dicer cofactor and a PKR inhibitor. However, the role of TRBP in microRNA (miRNA) biogenesis is controversial and its regulation of PKR in mitosis remains unexplored. Here, we generate TRBP knockout cells and find altered Dicer-processing sites in a subset of miRNAs but no effect on Dicer stability, miRNA abundance, or Argonaute loading. By generating PACT, another Dicer interactor, and TRBP/PACT double knockout (KO) cells, we further show that TRBP and PACT do not functionally compensate for one another and that only TRBP contributes to Dicer processing. We also report that TRBP is hyperphosphorylated by JNK in M phase when PKR is activated by cellular double-stranded RNAs (dsRNAs). Hyperphosphorylation potentiates the inhibitory activity of TRBP on PKR, suppressing PKR in M-G1 transition. By generating human TRBP KO cells, our study clarifies the role of TRBP and unveils negative feedback regulation of PKR through TRBP phosphorylation. PMID:25437560

Kim, Yoosik; Yeo, Jinah; Lee, Jung Hyun; Cho, Jun; Seo, Daekwan; Kim, Jong-Seo; Kim, V Narry

2014-11-01

261

Carbon Cycle  

NSDL National Science Digital Library

This interactive animation focuses on the carbon cycle and includes embedded videos and captioned images to provide greater clarification and detail of the cycle than would be available by a single static visual alone.

Sciencelearn

262

Functional genomics and SNP analysis of human genes encoding proline metabolic enzymes  

PubMed Central

Proline metabolism in mammals involves two other amino acids, glutamate and ornithine, and five enzymatic activities, ?1-pyrroline-5-carboxylate (P5C) reductase (P5CR), proline oxidase, P5C dehydrogenase, P5C synthase and ornithine-?-aminotransferase (OAT). With the exception of OAT, which catalyzes a reversible reaction, the other 4 enzymes are unidirectional, suggesting that proline metabolism is purpose-driven, tightly regulated, and compartmentalized. In addition, this tri-amino-acid system also links with three other pivotal metabolic systems, namely the TCA cycle, urea cycle, and pentose phosphate pathway. Abnormalities in proline metabolism are relevant in several diseases: six monogenic inborn errors involving metabolism and/or transport of proline and its immediate metabolites have been described. Recent advances in the Human Genome Project, in silico database mining techniques, and research in dissecting the molecular basis of proline metabolism prompted us to utilize functional genomic approaches to analyze human genes which encode proline metabolic enzymes in the context of gene structure, regulation of gene expression, mRNA variants, protein isoforms, and single nucleotide polymorphisms. PMID:18506409

Williams, D. Bart; Zhaorigetu, Siqin; Khalil, Shadi; Wan, Guanghua; Valle, David

2009-01-01

263

Water Cycle  

NSDL National Science Digital Library

Water Cycle fun From water cycle Web Quest Links Introduction Task Process Evaluation Conclusion Resources Teacher Guide Introduction Luke Warm, a weather man, and you will help two baseball players understand why the big game might be rained out. You will explore the Water cycle and ...

Mrs. Terry

2009-04-03

264

Functional impact of Aurora A-mediated phosphorylation of HP1? at serine 83 during cell cycle progression  

PubMed Central

Background Previous elegant studies performed in the fission yeast Schizosaccharomyces pombe have identified a requirement for heterochromatin protein 1 (HP1) for spindle pole formation and appropriate cell division. In mammalian cells, HP1? has been implicated in both somatic and germ cell proliferation. High levels of HP1? protein associate with enhanced cell proliferation and oncogenesis, while its genetic inactivation results in meiotic and mitotic failure. However, the regulation of HP1? by kinases, critical for supporting mitotic progression, remains to be fully characterized. Results We report for the first time that during mitotic cell division, HP1? colocalizes and is phosphorylated at serine 83 (Ser83) in G2/M phase by Aurora A. Since Aurora A regulates both cell proliferation and mitotic aberrations, we evaluated the role of HP1? in the regulation of these phenomena using siRNA-mediated knockdown, as well as phosphomimetic and nonphosphorylatable site-directed mutants. We found that genetic downregulation of HP1?, which decreases the levels of phosphorylation of HP1? at Ser83 (P-Ser83-HP1?), results in mitotic aberrations that can be rescued by reintroducing wild type HP1?, but not the nonphosphorylatable S83A-HP1? mutant. In addition, proliferation assays showed that the phosphomimetic S83D-HP1? increases 5-ethynyl-2´-deoxyuridine (EdU) incorporation, whereas the nonphosphorylatable S83A-HP1? mutant abrogates this effect. Genome-wide expression profiling revealed that the effects of these mutants on mitotic functions are congruently reflected in G2/M gene expression networks in a manner that mimics the on and off states for P-Ser83-HP1?. Conclusions This is the first description of a mitotic Aurora A-HP1? pathway, whose integrity is necessary for the execution of proper somatic cell division, providing insight into specific types of posttranslational modifications that associate to distinct functional outcomes of this important chromatin protein. PMID:23829974

2013-01-01

265

A Novel Function of RNAs Arising From the Long Terminal Repeat of Human Endogenous Retrovirus 9 in Cell Cycle Arrest  

PubMed Central

The human genome contains approximately 50 copies of the replication-defective human endogenous retrovirus 9 (ERV-9) and thousands of copies of its solitary long term repeat (sLTR) element. While some sLTRs are located upstream of critical genes and have enhancer activity, other sLTRs are located within introns and may be transcribed as RNAs. We found that intronic RNAs arising from U3 sLTRs of ERV-9 were expressed as both sense (S) and antisense (AS) transcripts in all human cells tested but that expression levels differed in malignant versus nonmalignant cells. In nonmalignant cells, AS was expressed at higher levels than S and at higher levels than in malignant cells; in malignant cells, AS was expressed at amounts equivalent to those of S RNA. Critically, U3 AS RNA was found to physically bind to key transcription factors for cellular proliferation, including NF-Y, p53, and sp1, indicating that such RNA transcripts may function as decoy targets or traps for NF-Y and thus inhibit the growth of human cancer cells. Indeed, short U3 oligodeoxynucleotides (ODNs) based on these RNA sequences ably inhibited proliferation of cancer cell lines driven by cyclins B1/B2, the gene targets of NF-Y. PMID:23097441

Xu, Lai; Elkahloun, Abdel G.; Candotti, Fabio; Grajkowski, Andrzej; Beaucage, Serge L.; Petricoin, Emanuel F.; Calvert, Valerie; Juhl, Hartmut; Mills, Frederick; Mason, Karen; Shastri, Neal; Chik, Josh; Xu, Cynthia

2013-01-01

266

The utilization of tricarboxylic acid cycle acids and the uptake of succinic acid by Neurospora crassa  

E-print Network

was affected by the carbon source of the medium used to grow t. e inoculum, Except for acetate, the TCA cycle acids supported better growth at pH 4. 1 than at pH 7. 0. 14 Fractionation of mycelia exposed to C-succinic acid indicated that more succinic acid... metabolic activity at the low temperature caused reduced accumulation of the radioactive label. Even if it is assumed that uptake alone was affected, with an approximate Q 0 of 1. 2 at pH 4. 1 and 1. 0 at pH 7, 0, it must be con- cluded that uptake...

Gilliland, Patti Lynn

1978-01-01

267

The Function of the Superficial Root Mat in the Biogeochemical Cycles of Nutrients in Congolese Eucalyptus Plantations  

PubMed Central

• Background and Aims The importance of superficial root mats inside the forest floor for the nutrition of Amazonian rain forests has been extensively investigated. The present study was aimed at assessing the function of a root mat adherent to decomposing organic material observed in Eucalyptus plantations. • Methods The development of the root mat was studied through micromorphological observations of thin litter sections, and the influence of soil microtopography and soil water repellency on root mat biomass was assessed in situ on an area of 5 m2. In addition, input–output budgets of nutrients within the forest floor were established from measurements of litterfall, dissolved nutrients in gravitational solutions, and forest floor nutrient contents. • Key Findings The amounts of nutrients released during litter decay in this ecosystem during the period of study were, on average, 46, 3, 4, 19 and 17 kg ha–1 year–1 for N, P, K, Ca and Mg, respectively. The simultaneous measurements of the chemical composition of throughfall solutions and leachates beneath the forest floor showed a very quick uptake of nutrients by the root mat during the decomposition processes. Indeed, the solutions did not become noticeably enriched in nutrients during their passage through the holorganic layer, despite large amounts of elements being released during litter decay. The root mat biomass decreased significantly during the dry season, and a preferential development in microdepressions at the soil surface was observed. A strong water repellency observed in these depressions might enhance the ability of the roots to take up water and nutrients during the dry periods. • Conclusions The root mat was active throughout the year to catch the flux of nutrients from the biodegradation of the forest floor, preventing the transfer of dissolved nutrients toward deeper soil horizons. This mechanism is involved in the successful adaptation of this Eucalyptus hybrid in areas covered by ‘climacic’ savannas in Congo. PMID:14749252

LACLAU, JEAN?PAUL; TOUTAIN, FRANÇOIS; M’BOU, ARMEL THONGO; ARNAUD, MICHEL; JOFFRE, RICHARD; RANGER, JACQUES

2004-01-01

268

Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community  

PubMed Central

Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbiological processes (that is, nitrification and denitrification). Soil amended with biochar (charcoal created by pyrolysis of biomass) has been demonstrated to increase crop yield, improve soil quality and affect greenhouse gas emissions, for example, reduce N2O emissions. Despite several studies on variations in the general microbial community structure due to soil biochar amendment, hitherto the specific role of the nitrogen cycling microbial community in mitigating soil N2O emissions has not been subject of systematic investigation. We performed a microcosm study with a water-saturated soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil. PMID:24067258

Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

2014-01-01

269

Centrosome structure and function is altered by chloral hydrate and diazepam during the first reproductive cell cycles in sea urchin eggs  

NASA Technical Reports Server (NTRS)

This paper explores the mode of action of the tranquillizers chloral hydrate and diazepam during fertilization and mitosis of the first reproductive cell cycles in sea urchin eggs. Most striking effects of these drugs are the alteration of centrosomal material and the abnormal microtubule configurations during exposure and after recovery from the drugs. This finding is utilized to study the mechanisms of centrosome compaction and decompaction and the dynamic configurational changes of centrosomal material and its interactions with microtubules. When 0.1% chloral hydrate or 350-750 microM diazepam is applied at specific phases during the first cell cycle of sea urchin eggs, expanded centrosomal material compacts at distinct regions and super-compacts into dense spheres while microtubules disassemble. When eggs are treated before pronuclear fusion, centrosomal material aggregates around each of the two pronuclei while microtubules disappear. Upon recovery, atypical asters oftentimes with multiple foci are formed from centrosomal material surrounding the pronuclei which indicates that the drugs have affected centrosomal material and prevent it from functioning normally. Electron microscopy and immunofluorescence studies with antibodies that routinely stain centrosomes in sea urchin eggs (4D2; and Ah-6) depict centrosomal material that is altered when compared to control cells. This centrosomal material is not able to reform normal microtubule patterns upon recovery but will form multiple asters around the two pronuclei. When cells are treated with 0.1% chloral hydrate or 350-750 microM diazepam during mitosis, the bipolar centrosomal material becomes compacted and aggregates into multiple dense spheres while spindle and polar microtubules disassemble. With increased incubation time, the smaller dense centrosome particles aggregate into bigger and fewer spheres. Upon recovery, unusual irregular microtubule configurations are formed from centrosomes that have lost their ability to reform normal mitotic figures. These results indicate that chloral hydrate and diazepam affect centrosome structure which results in the inability to reform normal microtubule formations and causes abnormal fertilization and mitosis.

Schatten, H.; Chakrabarti, A.

1998-01-01

270

Functional and molecular identification of intermediate-conductance Ca(2+)-activated K(+) channels in breast cancer cells: association with cell cycle progression.  

PubMed

We have previously reported that the hEAG K(+) channels are responsible for the potential membrane hyperpolarization that induces human breast cancer cell progression into the G1 phase of the cell cycle. In the present study, we evaluate the role and functional expression of the intermediate-conductance Ca(2+)-activated K(+) channel, hIK1-like, in controlling cell cycle progression. Our results demonstrate that hIK1 current density increased in cells synchronized at the end of the G1 or S phase compared with those in the early G1 phase. This increased current density paralleled the enhancement in hIK1 mRNA levels and the highly negative membrane potential. Furthermore, in cells synchronized at the end of G1 or S phases, basal cytosolic Ca(2+) concentration ([Ca(2+)](i)) was also higher than in cells arrested in early G1. Blocking hIK1 channels with a specific blocker, clotrimazole, induced both membrane potential depolarization and a decrease in the [Ca(2+)](i) in cells arrested at the end of G1 and S phases but not in cells arrested early in the G1 phase. Blocking hIK1 with clotrimazole also induced cell proliferation inhibition but to a lesser degree than blocking hEAG with astemizole. The two drugs were essentially additive, inhibiting MCF-7 cell proliferation by 82% and arresting >90% of cells in the G1 phase. Thus, although the progression of MCF-7 cells through the early G1 phase is dependent on the activation of hEAG K(+) channels, when it comes to G1 and checkpoint G1/S transition, the membrane potential appears to be primarily dependent on the hIK1-activity level. PMID:14985237

Ouadid-Ahidouch, Halima; Roudbaraki, Morad; Delcourt, Philippe; Ahidouch, Ahmed; Joury, Nathalie; Prevarskaya, Natalia

2004-07-01

271

Linking N2O emissions from biochar-amended soil to the structure and function of the N-cycling microbial community.  

PubMed

Nitrous oxide (N2O) contributes 8% to global greenhouse gas emissions. Agricultural sources represent about 60% of anthropogenic N2O emissions. Most agricultural N2O emissions are due to increased fertilizer application. A considerable fraction of nitrogen fertilizers are converted to N2O by microbiological processes (that is, nitrification and denitrification). Soil amended with biochar (charcoal created by pyrolysis of biomass) has been demonstrated to increase crop yield, improve soil quality and affect greenhouse gas emissions, for example, reduce N2O emissions. Despite several studies on variations in the general microbial community structure due to soil biochar amendment, hitherto the specific role of the nitrogen cycling microbial community in mitigating soil N2O emissions has not been subject of systematic investigation. We performed a microcosm study with a water-saturated soil amended with different amounts (0%, 2% and 10% (w/w)) of high-temperature biochar. By quantifying the abundance and activity of functional marker genes of microbial nitrogen fixation (nifH), nitrification (amoA) and denitrification (nirK, nirS and nosZ) using quantitative PCR we found that biochar addition enhanced microbial nitrous oxide reduction and increased the abundance of microorganisms capable of N2-fixation. Soil biochar amendment increased the relative gene and transcript copy numbers of the nosZ-encoded bacterial N2O reductase, suggesting a mechanistic link to the observed reduction in N2O emissions. Our findings contribute to a better understanding of the impact of biochar on the nitrogen cycling microbial community and the consequences of soil biochar amendment for microbial nitrogen transformation processes and N2O emissions from soil. PMID:24067258

Harter, Johannes; Krause, Hans-Martin; Schuettler, Stefanie; Ruser, Reiner; Fromme, Markus; Scholten, Thomas; Kappler, Andreas; Behrens, Sebastian

2014-03-01

272

The Chlamydomonas cell cycle.  

PubMed

The position of Chlamydomonas within the eukaryotic phylogeny makes it a unique model in at least two important ways: as a representative of the critically important, early-diverging lineage leading to plants; and as a microbe retaining important features of the last eukaryotic common ancestor (LECA) that has been lost in the highly studied yeast lineages. Its cell biology has been studied for many decades and it has well-developed experimental genetic tools, both classical (Mendelian) and molecular. Unlike land plants, it is a haploid with very few gene duplicates, making it ideal for loss-of-function genetic studies. The Chlamydomonas cell cycle has a striking temporal and functional separation between cell growth and rapid cell division, probably connected to the interplay between diurnal cycles that drive photosynthetic cell growth and the cell division cycle; it also exhibits a highly choreographed interaction between the cell cycle and its centriole-basal body-flagellar cycle. Here, we review the current status of studies of the Chlamydomonas cell cycle. We begin with an overview of cell-cycle control in the well-studied yeast and animal systems, which has yielded a canonical, well-supported model. We discuss briefly what is known about similarities and differences in plant cell-cycle control, compared with this model. We next review the cytology and cell biology of the multiple-fission cell cycle of Chlamydomonas. Lastly, we review recent genetic approaches and insights into Chlamydomonas cell-cycle regulation that have been enabled by a new generation of genomics-based tools. PMID:25690512

Cross, Frederick R; Umen, James G

2015-05-01

273

In silico assessment of the metabolic capabilities of an engineered functional reversal of the ?-oxidation cycle for the synthesis of longer-chain (C?4) products.  

PubMed

The modularity and versatility of an engineered functional reversal of the ?-oxidation cycle make it a promising platform for the synthesis of longer-chain (C?4) products. While the pathway has recently been exploited for the production of n-alcohols and carboxylic acids, fully capitalizing on its potential for the synthesis of a diverse set of product families requires a system-level assessment of its biosynthetic capabilities. To this end, we utilized a genome scale model of Escherichia coli, in combination with Flux Balance Analysis and Flux Variability Analysis, to determine the key characteristics and constraints of this pathway for the production of a variety of product families under fermentative conditions. This analysis revealed that the production of n-alcohols, alkanes, and fatty acids of lengths C3-C18 could be coupled to cell growth in a strain lacking native fermentative pathways, a characteristic enabling product synthesis at maximum rates, titers, and yields. While energetic and redox constraints limit the production of target compounds from alternative platforms such as the fatty acid biosynthesis and ?-ketoacid pathways, the metabolic efficiency of a ?-oxidation reversal allows the production of a wide range of products of varying length and functionality. The versatility of this platform was investigated through the simulation of various termination pathways for product synthesis along with the use of different priming molecules, demonstrating its potential for the efficient synthesis of a wide variety of functionalized compounds. Overall, specific metabolic manipulations suggested by this systems-level analysis include deletion of native fermentation pathways, the choice of priming molecules and specific routes for their synthesis, proper choice of termination enzymes, control of flux partitioning at the pyruvate node and the pentose phosphate pathway, and the use of an NADH-dependent trans-enoyl-CoA reductase instead of a ferredoxin-dependent enzyme. PMID:24569100

Cintolesi, Angela; Clomburg, James M; Gonzalez, Ramon

2014-05-01

274

TRIIODOTHYRONINE INCREASES MYOCARDIAL FUNCTION AND PYRUVATE ENTRY INTO THE CITRIC ACID CYCLE AFTER REPERFUSION IN A MODEL OF INFANT CARDIOPULMONARY BYPASS  

SciTech Connect

We utilized a translational model of infant CPB to test the hypothesis that T3 modulates pyruvate entry into the citric acid cycle (CAC) thereby providing the energy support for improved cardiac function after ischemia-reperfusion. Methods and Results: Neonatal piglets received intracoronary [2-13Carbon(13C)]-pyruvate for 40 minutes (8 mM) during control aerobic conditions (Cont) or immediately after reperfusion (IR) from global hypothermic ischemia. A third group (IR-Tr) received T3 (1.2 ug/kg) during reperfusion. We assessed absolute CAC intermediate levels (aCAC) and flux parameters into the CAC through oxidative pyruvate decarboxylation (PDC ) and anaplerotic carboxylation (PC; ) using 13C-labeled pyruvate and isotopomer analysis by gas and liquid chromatography-mass spectrometry and 13C NMR. Neither IR nor IR-Tr modified aCAC. However, compared to IR, T3 (group IR-Tr) increased cardiac power and oxygen consumption after CPB while elevating both PDC and PC (~ four-fold). T3 inhibited IR induced reductions in CAC intermediate molar percent enrichment (MPE) and oxaloacetate(citrate)/malate MPE ratio; an index of aspartate entry into the CAC. Conclusions: T3 markedly enhances PC and PDC thereby providing substrate for elevated cardiac function and work after reperfusion. The increases in pyruvate flux occur with preservation of the CAC intermediate pool. Additionally, T3 inhibition of reductions in CAC intermediate MPEs indicates that T3 reduces the reliance on amino acids (AA) for anaplerosis after reperfusion. Thus, AA should be more available for other functions such as protein synthesis.

Olson, Aaron; Bouchard, Bertrand; Ning, Xue-Han; Isern, Nancy G.; Des Rosiers, Christine; Portman, Michael A.

2012-03-01

275

The Regulatory Function of miR-200c on Inflammatory and Cell-Cycle Associated Genes in SK-LMS-1, A Leiomyosarcoma Cell Line.  

PubMed

Uterine leiomyosarcoma is a relatively rare malignancy with high mortality due to metastasis and chemoresistance. Leiomyosarcomas share similar morphological characteristics with leiomyomas which are considered to have the potential of transformation into leiomyosarcoma. Accumulated evidence suggests that microRNAs acting as regulators of gene expression at the posttranscriptional level play key roles in diverse biological processes including cellular transformation and tumorigenesis. We hypothesized that miR-200c, whose expression is altered in leiomyomas, equally plays a key role in pathogenesis of leiomyosarcoma. Using SK-LMS-1 leiomyosarcoma cell line as an in vitro model here, we found that the level of expression of miR-200c was significantly lower as compared to isolated leiomyoma smooth muscle cells. Overexpression (gain-of-function) of miR-200c in SK-LMS-1 through direct interaction with 3'-untranslated region of IKBKB, IL8, CDK2, and CCNE2, respectively, resulted in suppression of their expression as determined by quantitative polymerase chain reaction and Western blot analysis. Additionally, gain-of-function of miR-200c through inhibition of IKBKB expression resulted in decreased p65 transcriptional activity in IL8 promoter. Gain-of-function of miR-200c also increased SK-LMS-1 caspase 3/7 activity and inhibited their proliferation and migration. In summary, the results suggest that a progressive decline in miR-200c expression which alters transcriptional regulation of specific target genes that control nuclear factor-?B signaling pathway, inflammation, cell cycle, and migration, in part may promote development and progression of leiomyosarcomas, including their transformation from leiomyomas. PMID:25305131

Chuang, Tsai-Der; Ho, Matthew; Khorram, Omid

2014-10-01

276

carbon cycle  

NSDL National Science Digital Library

Life on earth is based on carbon. Living things acquire carbon from their environment - from air, water, soil, and rock and from other living things - through processes such as photosynthesis, respiration and decomposition. The carbon cycle model is a representation of the movement of carbon from sources to sinks through chemical and physical transfers. The carbon cycle activity allows students to see the effect of fossil fuel burning on the carbon cycle.

Maryland Virtual High School

277

Water Cycle  

NSDL National Science Digital Library

Students will use this short interactive activity to check their understanding on what they learned about the water cycle Do you drink the same water as your great grandparents did? Check this website then answer the following questions. COLLECTION 1. How many times does water go through the cycle? 2. Explain each part of the cycle and why it is important. 3. Construct a model or diagram based off the information from this ...

Lori Peterson

2009-09-28

278

Geological cycles  

Microsoft Academic Search

During the last hundred years, intensive studies have been made on the geological indications of the so called “Ice Ages”;. Already Penck and Bruckner discovered, around the end of the nineteenth century, the cyclic character of these phenomena and distinguished at least four cycles in the Alps area. In fact these geological cycles are controlled by climatic conditions. The geological

B. P. Hageman

1972-01-01

279

Role for a region of helically unstable DNA within the Epstein-Barr virus latent cycle origin of DNA replication oriP in origin function  

SciTech Connect

The minimal replicator of the Epstein-Barr virus (EBV) latent cycle origin of DNA replication oriP is composed of two binding sites for the Epstein-Barr virus nuclear antigen-1 (EBNA-1) and flanking inverted repeats that bind the telomere repeat binding factor TRF2. Although not required for minimal replicator activity, additional binding sites for EBNA-1 and TRF2 and one or more auxiliary elements located to the right of the EBNA-1/TRF2 sites are required for the efficient replication of oriP plasmids. Another region of oriP that is predicted to be destabilized by DNA supercoiling is shown here to be an important functional component of oriP. The ability of DNA fragments of unrelated sequence and possessing supercoiled-induced DNA duplex destabilized (SIDD) structures, but not fragments characterized by helically stable DNA, to substitute for this component of oriP demonstrates a role for the SIDD region in the initiation of oriP-plasmid DNA replication.

Polonskaya, Zhanna [Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794 (United States); Benham, Craig J. [Department of Mathematics, University of California at Davis, Davis, CA 95616 (United States); Hearing, Janet [Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794 (United States)]. E-mail: jhearing@ms.cc.sunysb.edu

2004-10-25

280

Identification and functional characterization of effectors in expressed sequence tags from various life cycle stages of the potato cyst nematode Globodera pallida.  

PubMed

In this article, we describe the analysis of over 9000 expressed sequence tags (ESTs) from cDNA libraries obtained from various life cycle stages of Globodera pallida. We have identified over 50 G. pallida effectors from this dataset using bioinformatics analysis, by screening clones in order to identify secreted proteins up-regulated after the onset of parasitism and using in situ hybridization to confirm the expression in pharyngeal gland cells. A substantial gene family encoding G. pallida SPRYSEC proteins has been identified. The expression of these genes is restricted to the dorsal pharyngeal gland cell. Different members of the SPRYSEC family of proteins from G. pallida show different subcellular localization patterns in plants, with some localized to the cytoplasm and others to the nucleus and nucleolus. Differences in subcellular localization may reflect diverse functional roles for each individual protein or, more likely, variety in the compartmentalization of plant proteins targeted by the nematode. Our data are therefore consistent with the suggestion that the SPRYSEC proteins suppress host defences, as suggested previously, and that they achieve this through interaction with a range of host targets. PMID:19849787

Jones, John T; Kumar, Amar; Pylypenko, Liliya A; Thirugnanasambandam, Amarnath; Castelli, Lydia; Chapman, Sean; Cock, Peter J A; Grenier, Eric; Lilley, Catherine J; Phillips, Mark S; Blok, Vivian C

2009-11-01

281

Cell cycle-dependent and DNA damage-inducible nuclear localization of FEN-1 nuclease is consistent with its dual functions in DNA replication and repair.  

PubMed

Flap endonuclease-1 (FEN-1), a 43-kDa protein, is a structure-specific and multifunctional nuclease. It plays important roles in RNA primer removal of Okazaki fragments during DNA replication, DNA base excision repair, and maintenance of genome stability. Three functional motifs of the enzyme were proposed to be responsible for its nuclease activities, interaction with proliferating cell nuclear antigen, and nuclear localization. In this study, we demonstrate in HeLa cells that a signal located at the C terminus (the nuclear localization signal (NLS) motif) facilitates nuclear localization of the enzyme during S phase of the cell cycle and in response to DNA damage. Truncation of the NLS motif prevents migration of the protein from the cytoplasm to the nucleus, while having no effect on the nuclease activities and its proliferating cell nuclear antigen interaction capability. Site-directed mutagenesis further revealed that a mutation of the KRK cluster to three alanine residues completely blocked the localization of FEN-1 into the nucleus, whereas mutagenesis of the KKK cluster led to a partial defect of nuclear localization in HeLa cells without observable phenotype in yeast. Therefore, the KRKXXXXXXXXKKK motif may be a bipartite NLS driving the protein into nuclei. Yeast RAD27Delta cells transformed with human mutant M(krk) survived poorly upon methyl methanesulfonate treatment or when they were incubated at an elevated temperature. PMID:11053418

Qiu, J; Li, X; Frank, G; Shen, B

2001-02-16

282

Thermal Fatigue of SnPb and SAC Resistor Joints: Analysis of Stress-Strain as a Function of Cycle Parameters  

Microsoft Academic Search

Accelerated thermal cycling (ATC) has been widely used in the microelectronics industry for reliability assessment. The relative effects of thermal cycling parameters (temperature range, dwell time, and ramp rate) and the failure mechanisms they induce have been the subject of many studies; however, uncertainty remains, particularly regarding the role of a very high ramp rate such as encountered in a

Yan Qi; Hamid R. Ghorbani; Jan K. Spelt

2006-01-01

283

Milankovitch Cycles  

NSDL National Science Digital Library

These animations depict the three major Milankovitch Cycles that impact global climate, visually demonstrating the definitions of eccentricity, obliquity, and precession, and their ranges of variation and timing on Earth.

[http://www.sciencecourseware.org/eec/GlobalWarming/Tutorials/Milankovitch/

284

Natural Cycle  

NSDL National Science Digital Library

In this short video from ClimateCentral, host Jessica Harrop explains what evidence scientists have for claiming that recent global warming is caused by humans and is not just part of a natural cycle.

Climate Central

285

Rock Cycle  

NSDL National Science Digital Library

This site, from Moorland School in England, describes the rock cycle. Topics briefly discussed include rock formation, erosion, transportation, and deposition, plus various types of rocks. The page is directed towards a middle-school audience.

Moorland School

286

Rock Cycle  

NSDL National Science Digital Library

The Rock Cycle SciPack explores different kinds and categories of rocks, the major processes through which they form and the cyclical nature of the formation and transformation of rock materials. The focus is on topics supporting Standards and Benchmarks related to the rock cycle as part of the transfer and transformation of matter and energy in Earth's system as well as a sense of the time scales involved and how rocks provide information about their own development and the history of Earth.In addition to comprehensive inquiry-based learning materials tied to Science Education Standards and Benchmarks, the SciPack includes the following additional components:? Pedagogical Implications section addressing common misconceptions, teaching resources and strand maps linking grade band appropriate content to standards. ? Access to one-on-one support via e-mail to content "Wizards".? Final Assessment which can be used to certify mastery of the concepts.Learning Outcomes:Rock Cycle: Categories by Process? List the three different types of rock. ? Make appropriate observations about rocks (e.g. describe rock composition and texture).? Make appropriate observations about the general environments in which the rocks formed.Rock Cycle: Environments of Formation? Realize that different rocks have specific origins, and that they are the product of any number of processes.? Identify the processes through which igneous, sedimentary, and metamorphic rock form.? Explain the role of intermediary materials such as sediment and magma in the formation of different kinds of rock.? Provide an overarching description of the steps in the rock cycle, the formation of sedimentary rock, the re-forming of rock by heat and pressure, and the process by which re-formed rock can return to the surface.Rock Cycle: Cycling? Recognize the formation and transformation processes as part of a continuing cycle.? Identify that while the form and location of different rocks change over time, the amount of material and the distribution among the elements remains constant.? Explain the different processes or paths that each type of rock may take in the rock cycle.Rock Cycle: Earth's Autobiography? State the amount of time over which the rock cycle has been in operation (4 billion years rather than 40 million or 400 million).? Recognize that the processes at work in the present are the same as those at work in the distant past.? Describe how rock formations and characteristics can be used to determine how different rock formed, making appropriate interpretations about the source of the rock, history and processes, and the environment of formation.? Describe how rocks provide a history of the changing surface of Earth and its lifeforms.

National Science Teachers Association (NSTA)

2007-03-21

287

Functional expression of chloride channels and their roles in the cell cycle and cell proliferation in highly differentiated nasopharyngeal carcinoma cells.  

PubMed

We previously demonstrated that the growth of the poorly differentiated nasopharyngeal carcinoma cells (CNE-2Z) was more dependent on the activities of volume-activated chloride channels than that of the normal nasopharyngeal epithelial cells (NP69-SV40T). However, the activities and roles of such volume-activated chloride channels in highly differentiated nasopharyngeal carcinoma cells (CNE-1) are not clarified. In this study, it was found that a volume-activated chloride current and a regulatory volume decrease (RVD) were induced by 47% hypotonic challenges. The current density and the capacity of RVD in the highly differentiated CNE-1 cells were lower than those in the poorly differentiated CNE-2Z cells, and higher than those in the normal cells (NP69-SV40T). The chloride channel blockers, 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and tamoxifen inhibited the current and RVD. Depletion of intracellular Cl(-) abolished the RVD. The chloride channel blockers reversibly inhibited cell proliferation in a concentration- and time-dependent manner, and arrested cells at the G0/G1 phases, but did not change cell viability. The sensitivity of the three cell lines to the chloride channel blockers was different, with the highest in poorly differentiated cells (CNE-2Z) and the lowest in the normal cells (NP69-SV40T). ClC-3 proteins were expressed in the three cells and distributed inside the cells as well as on the cell membrane. In conclusion, the highly differentiated nasopharyngeal carcinoma CNE-1 cells functionally expressed the volume-activated chloride channels, which may play important roles in controlling cell proliferation through modulating the cell cycle, and may be associated with cell differentiation. Chloride channels may be a potential target of anticancer therapy. PMID:25214521

Huang, Weiyuan; Liu, Mei; Zhu, Linyan; Liu, Shanwen; Luo, Hai; Ma, Lianshun; Wang, Haibo; Lu, Ruiling; Sun, Xiaoxue; Chen, Lixin; Wang, Liwei

2014-09-01

288

Transcription factors and glyoxylate cycle genes prominent in the transition of soybean cotyledons to the first functional leaves of the seedling.  

PubMed

During early seedling growth, the cotyledons transition from a storage tissue to become effectively the first leaf-like structures of the plant. In this programmed developmental process, they likely undergo a massive change in gene expression to redirect their metabolism and physiological processes. To define the developmental shifts in gene expression and begin to understand the gene regulatory networks that set this transition in motion, we carried out high-throughput RNA sequencing of cotyledons from seven developmental stages of soybean seedlings. We identified 154 gene models with high expression exclusively in the early seedling stages. A significant number (about 25 %) of those genes with known annotations were involved in carbohydrate metabolism. A detailed examination of glyoxylate cycle genes revealed the upregulation of their expression in the early stages of development. A total of approximately 50 % of the highly expressed genes whose expression peaked in the mid-developmental stages encoded ribosomal family proteins. Our analysis also identified 219 gene models with high expression at late developmental stages. The majority of these genes are involved in photosynthesis, including photosystem I- and II-associated genes. Additionally, the advantage of RNA-Seq to detect genes expressed at low levels revealed approximately 460 transcription factors with notable expression in at least one stage of the developing soybean seedling. Relatively over-represented transcription factor genes encode AP2, zinc finger, NAC, WRKY, and MYB families. These transcription factor genes may lead to the transcriptional reprogramming during the transition of seedling cotyledons from storage tissue to metabolically active organs that serve as the first functional leaves of the plant. PMID:25070765

Shamimuzzaman, Md; Vodkin, Lila

2014-12-01

289

Vapor Compression Cycle Design Program (CYCLE_D)  

National Institute of Standards and Technology Data Gateway

SRD 49 NIST Vapor Compression Cycle Design Program (CYCLE_D) (PC database for purchase)   The CYCLE_D database package simulates the vapor compression refrigeration cycles. It is fully compatible with REFPROP 9.0 and covers the 62 single-compound refrigerants . Fluids can be used in mixtures comprising up to five components.

290

Hydrological cycle.  

PubMed

The Pantanal hydrological cycle holds an important meaning in the Alto Paraguay Basin, comprising two areas with considerably diverse conditions regarding natural and water resources: the Plateau and the Plains. From the perspective of the ecosystem function, the hydrological flow in the relationship between plateau and plains is important for the creation of reproductive and feeding niches for the regional biodiversity. In general, river declivity in the plateau is 0.6 m/km while declivity on the plains varies from 0.1 to 0.3 m/km. The environment in the plains is characteristically seasonal and is home to an exuberant and abundant diversity of species, including some animals threatened with extinction. When the flat surface meets the plains there is a diminished water flow on the riverbeds and, during the rainy season the rivers overflow their banks, flooding the lowlands. Average annual precipitation in the Basin is 1,396 mm, ranging from 800 mm to 1,600 mm, and the heaviest rainfall occurs in the plateau region. The low drainage capacity of the rivers and lakes that shape the Pantanal, coupled with the climate in the region, produce very high evaporation: approximately 60% of all the waters coming from the plateau are lost through evaporation. The Alto Paraguay Basin, including the Pantanal, while boasting an abundant availability of water resources, also has some spots with water scarcity in some sub-basins, at different times of the year. Climate conditions alone are not enough to explain the differences observed in the Paraguay River regime and some of its tributaries. The complexity of the hydrologic regime of the Paraguay River is due to the low declivity of the lands that comprise the Mato Grosso plains and plateau (50 to 30 cm/km from east to west and 3 to 1.5 cm/km from north to south) as well as the area's dimension, which remains periodically flooded with a large volume of water. PMID:21537597

Gonçalves, H C; Mercante, M A; Santos, E T

2011-04-01

291

Carbon Cycle  

NSDL National Science Digital Library

This activity from NOAA Earth System Research Laboratory introduces students to the current scientific understanding of the greenhouse effect and the carbon cycle. The activity leads them through several interactive tasks investigating recent trends in atmospheric carbon dioxide. Students analyze scientific data and use scientific reasoning to determine the causes responsible for these recent trends. By studying carbon cycle science in a visual and interactive manner, the activity provides students with a conceptual framework with which to address the challenges of a changing climate.

NOAA/Earth System Research Laboratory

292

Glutamine fuels a vicious cycle of autophagy in the tumor stroma and oxidative mitochondrial metabolism in epithelial cancer cells: implications for preventing chemotherapy resistance.  

PubMed

Glutamine metabolism is crucial for cancer cell growth via the generation of intermediate molecules in the tricarboxylic acid (TCA) cycle, antioxidants and ammonia. The goal of the current study was to evaluate the effects of glutamine on metabolism in the breast cancer tumor microenvironment, with a focus on autophagy and cell death in both epithelial and stromal compartments. For this purpose, MCF7 breast cancer cells were cultured alone or co-cultured with non-transformed fibroblasts in media containing high glutamine and low glucose (glutamine +) or under control conditions, with no glutamine and high glucose (glutamine -). Here, we show that MCF7 cells maintained in co-culture with glutamine display increased mitochondrial mass, as compared with control conditions. Importantly, treatment with the autophagy inhibitor chloroquine abolishes the glutamine-induced augmentation of mitochondrial mass. It is known that loss of caveolin-1 (Cav-1) expression in fibroblasts is associated with increased autophagy and an aggressive tumor microenvironment. Here, we show that Cav-1 downregulation which occurs in fibroblasts maintained in co-culture specifically requires glutamine. Interestingly, glutamine increases the expression of autophagy markers in fibroblasts, but decreases expression of autophagy markers in MCF7 cells, indicating that glutamine regulates the autophagy program in a compartment-specific manner. Functionally, glutamine protects MCF7 cells against apoptosis, via the upregulation of the anti-apoptotic and anti-autophagic protein TIGAR. Also, we show that glutamine cooperates with stromal fibroblasts to confer tamoxifen-resistance in MCF7 cancer cells. Finally, we provide evidence that co-culture with fibroblasts (1) promotes glutamine catabolism, and (2) decreases glutamine synthesis in MCF7 cancer cells. Taken together, our findings suggest that autophagic fibroblasts may serve as a key source of energy-rich glutamine to fuel cancer cell mitochondrial activity, driving a vicious cycle of catabolism in the tumor stroma and anabolic tumor cell expansion. PMID:22236876

Ko, Ying-Hui; Lin, Zhao; Flomenberg, Neal; Pestell, Richard G; Howell, Anthony; Sotgia, Federica; Lisanti, Michael P; Martinez-Outschoorn, Ubaldo E

2011-12-15

293

Phosphorylation of minichromosome maintenance protein 7 (MCM7) by cyclin/cyclin-dependent kinase affects its function in cell cycle regulation.  

PubMed

MCM7 is one of the subunits of the MCM2-7 complex that plays a critical role in DNA replication initiation and cell proliferation of eukaryotic cells. After forming the pre-replication complex (pre-RC) with other components, the MCM2-7 complex is activated by DDK/cyclin-dependent kinase to initiate DNA replication. Each subunit of the MCM2-7 complex functions differently under regulation of various kinases on the specific site, which needs to be investigated in detail. In this study, we demonstrated that MCM7 is a substrate of cyclin E/Cdk2 and can be phosphorylated on Ser-121. We found that the distribution of MCM7-S121A is different from wild-type MCM7 and that the MCM7-S121A mutant is much less efficient to form a pre-RC complex with MCM3/MCM5/cdc45 compared with wild-type MCM7. By using the Tet-On inducible HeLa cell line, we revealed that overexpression of wild-type MCM7 but not MCM7-S121A can block S phase entry, suggesting that an excess of the pre-RC complex may activate the cell cycle checkpoint. Further analysis indicates that the Chk1 pathway is activated in MCM7-overexpressed cells in a p53-dependent manner. We performed experiments with the human normal cell line HL-7702 and also observed that overexpression of MCM7 can cause S phase block through checkpoint activation. In addition, we found that MCM7 could also be phosphorylated by cyclin B/Cdk1 on Ser-121 both in vitro and in vivo. Furthermore, overexpression of MCM7-S121A causes an obvious M phase exit delay, which suggests that phosphorylation of MCM7 on Ser-121 in M phase is very important for a proper mitotic exit. These data suggest that the phosphorylation of MCM7 on Ser-121 by cyclin/Cdks is involved in preventing DNA rereplication as well as in regulation of the mitotic exit. PMID:23720738

Wei, Qian; Li, Junhui; Liu, Ting; Tong, Xiaomei; Ye, Xin

2013-07-01

294

Menu Cycles.  

ERIC Educational Resources Information Center

The curriculum guide for commercial foods instruction is designed to aid the teacher in communicating the importance of menu cycles in commercial food production. It also provides information about the necessary steps in getting food from the raw form to the finished product, and then to the consumer. In addition to providing information on how to…

Clayton, Alfred; Almony, John

295

Nitrogen Cycle  

NSDL National Science Digital Library

This publication provides a variety of resources. Some assist you in your content knowledge, some are actual lessons or activities, some are good graphic representations of both concepts and organisms of the nitrogen cycle, and some provide real data from current issues for you and your students to analyze and interpret.

Mary LeFever

2007-01-01

296

Cycle Sequencing  

NSDL National Science Digital Library

This animation from Cold Spring Harbor Laboratory's Dolan DNA Learning Center presents the cycle sequencing. The animation contains instructions on how to sequence a piece of DNA beginning with the raw materials needed, and details on the process: "Fluorescent dyes are added to the reactions, and a laser within an automated DNA sequencing machine is used to analyze the DNA fragments produced."

297

Sulfur cycle  

Microsoft Academic Search

Even granting our uncertainties about parts of our model of the sulfur cycle, we can draw some conclusions from it. Man is now contributing about one half as much as nature to the total atmospheric burden of sulfur compounds, but by A.D. 2000 he will be contributing about as much, and in the northern hemisphere alone he will be more

W. W. Kellogg; R. D. Cadle; E. R. Allen; A. L. Lazrus; E. A. Martell

1972-01-01

298

The urea cycle disorders.  

PubMed

The urea cycle is the primary nitrogen-disposal pathway in humans. It requires the coordinated function of six enzymes and two mitochondrial transporters to catalyze the conversion of a molecule of ammonia, the ?-nitrogen of aspartate, and bicarbonate into urea. Whereas ammonia is toxic, urea is relatively inert, soluble in water, and readily excreted by the kidney in the urine. Accumulation of ammonia and other toxic intermediates of the cycle lead to predominantly neurologic sequelae. The disorders may present at any age from the neonatal period to adulthood, with the more severely affected patients presenting earlier in life. Patients are at risk for metabolic decompensation throughout life, often triggered by illness, fasting, surgery and postoperative states, peripartum, stress, and increased exogenous protein load. Here the authors address neurologic presentations of ornithine transcarbamylase deficiency in detail, the most common of the urea cycle disorders, neuropathology, neurophysiology, and our studies in neuroimaging. Special attention to late-onset presentations is given. PMID:25192511

Helman, Guy; Pacheco-Colón, Ileana; Gropman, Andrea L

2014-07-01

299

The Water Cycle  

NSDL National Science Digital Library

4th Grade Science Learn all about the Water Cycle! The Water Cycle: Water Storage Learn about Evaporation, Condensation, Precipitation, and Collection! The Water Cycle Here are some activites to learn about the water cycle. Hydrologic Cycle ...

Ms. Andrus

2007-10-12

300

Rock Cycle  

NSDL National Science Digital Library

Through five lessons, students are introduced to all facets of the rock cycle. Topics include rock and mineral types, material stresses and weathering, geologic time and fossil formation, the Earth's crust and tectonic plates, and soil formation and composition. Lessons are presented in the context of the related impact on humans in the form of roadway and tunnel design and construction, natural disasters, environmental site assessment for building structures, and measurement instrumentation and tools. Hands-on activities include experiencing tensional, compressional and shear material stress by using only hand force to break bars of soap; preparing Jeopardy-type trivia questions/answers for a class game that reinforces students' understanding of rocks and the rock cycle; creating "fossils" using melted chocolate; working within design constraints to design and build a model tunnel through a clay mountain; and soil sampling by creating tools, obtaining soil cores, documenting a soil profile log, and analyzing the findings to make engineering predictions.

Integrated Teaching and Learning Program,

301

Carbon Cycle  

NSDL National Science Digital Library

Elementary students often successfully memorize and repeat back the stages in cycles, with no deep conceptual understanding of the complexities of the processes involved. Their ability to synthesize knowledge of the cycles with a wider breadth of information related to real-world, unresolved environmental issues such as global warming, greenhouse gas emissions or the burning of biomass for fuel is probably less well developed. In order to engage in meaningful discussions of carbon-related environmental issues, students also need an understanding of the changing nature of the earth s atmosphere. The relative proportion of nitrogen, carbon dioxide, oxygen, ozone and other gases is neither consistent around the world nor constant over time. What factors contribute to the variability in atmospheric content? Which of the factors should be controlled? What are the possible approaches to controlling them? What are the possible and probable outcomes of such controlling measures?

Mary LeFever

2007-01-01

302

Acclimation to Chronic O3 in Field-grown Soybean is Characterized by Increased Levels of TCA Cycle Transcripts and ROS Scavenging Compounds in Addition to Decreased Photosynthetic Capacity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tropospheric ozone (O3) is a pollutant that is generated by volatile organic compounds, nitrogen oxides and sunlight. When plants take in O3 through stomata, harmful reactive oxygen species (ROS) are produced that induce the production of ROS scavenging antioxidants. Climate change predictions indic...

303

Quantitative PCR Analysis of Functional Genes in Iron-Rich Microbial Mats at an Active Hydrothermal Vent System (L?'ihi Seamount, Hawai'i).  

PubMed

The chemolithotrophic Zetaproteobacteria represent a novel class of Proteobacteria which oxidize Fe(II) to Fe(III) and are the dominant bacterial population in iron-rich microbial mats. Zetaproteobacteria were first discovered at L?'ihi Seamount, located 35 km southeast off the big island of Hawai'i, which is characterized by low-temperature diffuse hydrothermal venting. Novel nondegenerate quantitative PCR (qPCR) assays for genes associated with microbial nitrogen fixation, denitrification, arsenic detoxification, Calvin-Benson-Bassham (CBB), and reductive tricarboxylic acid (rTCA) cycles were developed using selected microbial mat community-derived metagenomes. Nitrogen fixation genes were not detected, but all other functional genes were present. This suggests that arsenic detoxification and denitrification processes are likely cooccurring in addition to two modes of carbon fixation. Two groups of microbial mat community types were identified by terminal restriction fragment length polymorphism (T-RFLP) and were further described based on qPCR data for zetaproteobacterial abundance and carbon fixation mode preference. qPCR variance was associated with mat morphology but not with temperature or sample site. Geochemistry data were significantly associated with sample site and mat morphology. Together, these qPCR assays constitute a functional gene signature for iron microbial mat communities across a broad array of temperatures, mat types, chemistries, and sampling sites at L?'ihi Seamount. PMID:25681182

Jesser, Kelsey J; Fullerton, Heather; Hager, Kevin W; Moyer, Craig L

2015-05-01

304

Modulation of primary cell function of host Pseudomonas bacteria by the conjugative plasmid pCAR1.  

PubMed

The impacts of plasmid carriage on the host cell were comprehensively analysed using the conjugative plasmid pCAR1 in three different Pseudomonas hosts, P.?putida?KT2440, P.?aeruginosa?PAO1 and P.?fluorescens?Pf0-1. Plasmid carriage reduced host fitness, swimming motility, and resistance to osmotic or pH stress. Plasmid carriage brought about alterations in primary metabolic capacities in the TCA cycle of the hosts. Differentially transcribed genes in the three hosts associated with plasmid carriage were identified by growth phase-dependent transcriptome analyses. Plasmid carriage commonly showed a greater effect on the host transcriptome at the transition and early stationary phases. The transcriptome alterations were similar between KT2440 and PAO1. Transcriptions of numbers of genes encoding ribosomal proteins, F-type ATPase, and RNAP core in both strains were not suppressed enough in the early stationary phase by plasmid carriage. These responses may have been responsible for the reduction in host fitness, motility and stress resistances. Host-specific responses to plasmid carriage were transcriptional changes of genes on putative prophage or foreign DNA regions. The extents of the impacts on host phenotypes and transcriptomes were similarly greatest in KT2440 and lowest in Pf0-1. These findings suggest that host cell function was actively regulated by plasmid carriage. PMID:24889869

Takahashi, Yurika; Shintani, Masaki; Takase, Noriyuki; Kazo, Yuka; Kawamura, Fujio; Hara, Hirofumi; Nishida, Hiromi; Okada, Kazunori; Yamane, Hisakazu; Nojiri, Hideaki

2015-01-01

305

The pyruvate-tricarboxylic acid cycle node: a focal point of virulence control in the enteric pathogen Yersinia pseudotuberculosis.  

PubMed

Despite our increasing knowledge of the specific pathogenicity factors in bacteria, the contribution of metabolic processes to virulence is largely unknown. Here, we elucidate a tight connection between pathogenicity and core metabolism in the enteric pathogen Yersinia pseudotuberculosis by integrated transcriptome and [(13)C]fluxome analysis of the wild type and virulence-regulator mutants. During aerobic growth on glucose, Y. pseudotuberculosis reveals an unusual flux distribution with a high level of secreted pyruvate. The absence of the transcriptional and post-transcriptional regulators RovA, CsrA, and Crp strongly perturbs the fluxes of carbon core metabolism at the level of pyruvate metabolism and the tricarboxylic acid (TCA) cycle, and these perturbations are accompanied by transcriptional changes in the corresponding enzymes. Knock-outs of regulators of this metabolic branch point and of its central enzyme, pyruvate kinase (?pykF), result in mutants with significantly reduced virulence in an oral mouse infection model. In summary, our work identifies the pyruvate-TCA cycle node as a focal point for controlling the host colonization and virulence of Yersinia. PMID:25164818

Bücker, René; Heroven, Ann Kathrin; Becker, Judith; Dersch, Petra; Wittmann, Christoph

2014-10-24

306

Metabolic engineering of Lactobacillus plantarum for succinic acid production through activation of the reductive branch of the tricarboxylic acid cycle.  

PubMed

Biosynthesis of succinic acid is an alternative method from conventional chemical synthesis. For this application, several bacteria and fungi have been employed and genetically modified. Lactic acid bacteria (LAB) are gaining recognition as novel producers of useful compounds by metabolic engineering. Among LAB, Lactobacillus plantarum NCIMB 8826 is an interesting candidate for succinic acid production by metabolic engineering since it has an incomplete tricarboxylic acid (TCA) cycle and naturally produces small amounts of succinic acid. In this study, we constructed recombinant LAB and evaluated them as hosts of succinic acid production. We examined the enzymes pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), and malic enzyme for their potential to improve metabolic flux from glycolysis to the reductive TCA cycle in a lactate dehydrogenase-deficient strain of L. plantarum NCIMB 8826 (VL103). We investigated the effects of overexpression or coexpression of each enzyme on succinic acid production. Our results suggested that PC is the key enzyme for succinic acid production by L. plantarum VL103, whereas PEPCK is critical for increasing biomass. The highest yield of succinic acid was obtained through coexpression of PC and PEPCK in L. plantarum VL103. This recombinant strain produced a 22-fold higher amount of succinic acid than the wild-type and converted 25.3% of glucose to succinic acid. PMID:23769309

Tsuji, Akira; Okada, Sanae; Hols, Pascal; Satoh, Eiichi

2013-07-10

307

Module structure of interphotoreceptor retinoid-binding protein (IRBP) may provide bases for its complex role in the visual cycle – structure\\/function study of Xenopus IRBP  

Microsoft Academic Search

BACKGROUND: Interphotoreceptor retinoid-binding protein's (IRBP) remarkable module structure may be critical to its role in mediating the transport of all-trans and 11-cis retinol, and 11-cis retinal between rods, cones, RPE and Müller cells during the visual cycle. We isolated cDNAs for Xenopus IRBP, and expressed and purified its individual modules, module combinations, and the full-length polypeptide. Binding of all-trans retinol,

Federico Gonzalez-Fernandez; Claxton A Baer; Debashis Ghosh

2007-01-01

308

Cyclical Cycles  

NSDL National Science Digital Library

In this activity, students model the water cycle using a set of glass bowls, water, salt, clear plastic wrap, and a marble. and observe the process of evaporation, condensation, and precipitation. They observe that water can change from a liquid to a gas, and change back into a liquid. The resource is part of the teacher's guide accompanying the video, NASA SCI Files: The Case of the Phenomenal Weather. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

2012-08-03

309

13 C NMR analysis reveals a link between L-glutamine metabolism, D-glucose metabolism and ?-glutamyl cycle activity in a clonal pancreatic beta-cell line  

Microsoft Academic Search

Aims\\/hypothesis  Pancreatic islet cells and clonal beta-cell lines can metabolise L-glutamine at high rates. The pathway of L-glutamine metabolism has traditionally been described as L-glutamineL-glutamate2-oxoglutarateoxidation in TCA cycle following conversion to pyruvate. Controversially, the metabolism of D-glucose to L-glutamate in beta cells is not widely accepted. However, L-glutamate has been proposed to be a stimulation-secretion coupling factor in glucose-induced insulin secretion.

L. Brennan; M. Corless; C. Hewage; J. P. G. Malthouse; N. H. McClenaghan; P. R. Flatt; P. Newsholme

2003-01-01

310

Functional Interactions between BM88/Cend1, Ran-Binding Protein M and Dyrk1B Kinase Affect Cyclin D1 Levels and Cell Cycle Progression/Exit in Mouse Neuroblastoma Cells  

PubMed Central

BM88/Cend1 is a neuronal-lineage specific modulator with a pivotal role in coordination of cell cycle exit and differentiation of neuronal precursors. In the current study we identified the signal transduction scaffolding protein Ran-binding protein M (RanBPM) as a BM88/Cend1 binding partner and showed that BM88/Cend1, RanBPM and the dual specificity tyrosine-phosphorylation regulated kinase 1B (Dyrk1B) are expressed in mouse brain as well as in cultured embryonic cortical neurons while RanBPM can form complexes with either of the two other proteins. To elucidate a potential mechanism involving BM88/Cend1, RanBPM and Dyrk1B in cell cycle progression/exit, we transiently co-expressed these proteins in mouse neuroblastoma Neuro 2a cells. We found that the BM88/Cend1-dependent or Dyrk1B-dependent down-regulation of cyclin D1 is reversed following their functional interaction with RanBPM. More specifically, functional interaction of RanBPM with either BM88/Cend1 or Dyrk1B stabilizes cyclin D1 in the nucleus and promotes 5-bromo-2'-deoxyuridine (BrdU) incorporation as a measure of enhanced cell proliferation. However, the RanBPM-dependent Dyrk1B cytosolic retention and degradation is reverted in the presence of Cend1 resulting in cyclin D1 destabilization. Co-expression of RanBPM with either BM88/Cend1 or Dyrk1B also had a negative effect on Neuro 2a cell differentiation. Our results suggest that functional interactions between BM88/Cend1, RanBPM and Dyrk1B affect the balance between cellular proliferation and differentiation in Neuro 2a cells and indicate that a potentially similar mechanism may influence cell cycle progression/exit and differentiation of neuronal precursors. PMID:24312406

Tsioras, Konstantinos; Papastefanaki, Florentia; Politis, Panagiotis K.; Matsas, Rebecca; Gaitanou, Maria

2013-01-01

311

The Usher 1B protein, MYO7A, is required for normal localization and function of the visual retinoid cycle enzyme, RPE65  

PubMed Central

Mutations in the MYO7A gene cause a deaf-blindness disorder, known as Usher syndrome 1B.  In the retina, the majority of MYO7A is in the retinal pigmented epithelium (RPE), where many of the reactions of the visual retinoid cycle take place.  We have observed that the retinas of Myo7a-mutant mice are resistant to acute light damage. In exploring the basis of this resistance, we found that Myo7a-mutant mice have lower levels of RPE65, the RPE isomerase that has a key role in the retinoid cycle.  We show for the first time that RPE65 normally undergoes a light-dependent translocation to become more concentrated in the central region of the RPE cells.  This translocation requires MYO7A, so that, in Myo7a-mutant mice, RPE65 is partly mislocalized in the light.  RPE65 is degraded more quickly in Myo7a-mutant mice, perhaps due to its mislocalization, providing a plausible explanation for its lower levels.  Following a 50–60% photobleach, Myo7a-mutant retinas exhibited increased all-trans-retinyl ester levels during the initial stages of dark recovery, consistent with a deficiency in RPE65 activity.  Lastly, MYO7A and RPE65 were co-immunoprecipitated from RPE cell lysate by antibodies against either of the proteins, and the two proteins were partly colocalized, suggesting a direct or indirect interaction.  Together, the results support a role for MYO7A in the translocation of RPE65, illustrating the involvement of a molecular motor in the spatiotemporal organization of the retinoid cycle in vision. PMID:21493626

Lopes, Vanda S.; Gibbs, Daniel; Libby, Richard T.; Aleman, Tomas S.; Welch, Darcy L.; Lillo, Concepción; Jacobson, Samuel G.; Radu, Roxana A.; Steel, Karen P.; Williams, David S.

2011-01-01

312

Inferring deep biosphere function and diversity through (near) surface biosphere portals (Invited)  

NASA Astrophysics Data System (ADS)

The consideration of surface expressions of the deep subsurface- such as springs- remains one of the most economically viable means to query the deep biosphere's diversity and function. Hot spring source pools are ideal portals for accessing and inferring the taxonomic and functional diversity of related deep subsurface microbial communities. Consideration of the geochemical composition of deep vs. surface fluids provides context for interpretation of community function. Further, parallel assessment of 16S rRNA data, metagenomic sequencing, and isotopic compositions of biomass in surface springs allows inference of the functional capacities of subsurface ecosystems. Springs in Yellowstone National Park (YNP), the Philippines, and Turkey are considered here, incorporating near-surface, transition, and surface ecosystems to identify 'legacy' taxa and functions of the deep biosphere. We find that source pools often support functional capacity suited to subsurface ecosystems. For example, in hot ecosystems, source pools are strictly chemosynthetic, and surface environments with measureable dissolved oxygen may contain evidence of community functions more favorable under anaerobic conditions. Metagenomic reads from a YNP ecosystem indicate the genetic capacity for sulfate reduction at high temperature. However, inorganic sulfate reduction is only minimally energy-yielding in these surface environments suggesting the potential that sulfate reduction is a 'legacy' function of deeper biosphere ecosystems. Carbon fixation tactics shift with increased surface exposure of the thermal fluids. Genes related to the rTCA cycle and the acetyl co-A pathway are most prevalent in highest temperature, anaerobic sites. At lower temperature sites, fewer total carbon fixation genes were observed, perhaps indicating an increase in heterotrophic metabolism with increased surface exposure. In hydrogen and methane rich springs in the Philippines and Turkey, methanogenic taxa dominate source spring archaeal communities, however methanogenesis is predicted to not be a viable metabolic function. Bacterial communities dominated by heterotrophic taxa suggest that the inorganic carbon-poor deeper subsurface fluids do not support autotrophic metabolic functions. Transitions in community functional and taxonomic diversity as a result of transitions in environment, for example as a result of fluid cooling/mixing or in response to climate-related stimulus, drive community plasticity and redundancy. Together, these surface-related datasets allow informed reconstruction of biogeochemical processes and microbial community diversity relevant to deep subsurface communities, and along with other recent work broaden our view of community function in deep subsurface hydrothermal ecosystems and the transition to surface environments.

Meyer-Dombard, D. R.; Cardace, D.; Woycheese, K. M.; Swingley, W.; Schubotz, F.; Shock, E.

2013-12-01

313

A Synthesis of Solar Cycle Prediction Techniques  

NASA Technical Reports Server (NTRS)

A number of techniques currently in use for predicting solar activity on a solar cycle timescale are tested with historical data. Some techniques, e.g., regression and curve fitting, work well as solar activity approaches maximum and provide a month-by-month description of future activity, while others, e.g., geomagnetic precursors, work well near solar minimum but only provide an estimate of the amplitude of the cycle. A synthesis of different techniques is shown to provide a more accurate and useful forecast of solar cycle activity levels. A combination of two uncorrelated geomagnetic precursor techniques provides a more accurate prediction for the amplitude of a solar activity cycle at a time well before activity minimum. This combined precursor method gives a smoothed sunspot number maximum of 154 plus or minus 21 at the 95% level of confidence for the next cycle maximum. A mathematical function dependent on the time of cycle initiation and the cycle amplitude is used to describe the level of solar activity month by month for the next cycle. As the time of cycle maximum approaches a better estimate of the cycle activity is obtained by including the fit between previous activity levels and this function. This Combined Solar Cycle Activity Forecast gives, as of January 1999, a smoothed sunspot maximum of 146 plus or minus 20 at the 95% level of confidence for the next cycle maximum.

Hathaway, David H.; Wilson, Robert M.; Reichmann, Edwin J.

1999-01-01

314

The Nitrogen Cycle  

NSDL National Science Digital Library

You are going to learn about the nitrogen cycle. After finishing these activities, you will be able to draw the nitrogen cycle and explain how human activity affects it. 1. Explore this website to learn some basic information about the nitrogen cycle. The Nitrogen Cycle 2. Discover additional information about the nitrogen cycle by looking at more websites. The Nitrogen Cycle: Of Microbes and Men Introduction to the Biosphere: The Nitrogen Cycle 3. Draw your own diagram ...

Albion Middle School Library--Mrs. Bates

2006-10-06

315

Modeling the Nuclear Fuel Cycle  

SciTech Connect

A review of existing nuclear fuel cycle systems analysis codes was performed to determine if any existing codes meet technical and functional requirements defined for a U.S. national program supporting the global and domestic assessment, development and deployment of nuclear energy systems. The program would be implemented using an interconnected architecture of different codes ranging from the fuel cycle analysis code, which is the subject of the review, to fundamental physical and mechanistic codes. Four main functions are defined for the code: (1) the ability to characterize and deploy individual fuel cycle facilities and reactors in a simulation, while discretely tracking material movements, (2) the capability to perform an uncertainty analysis for each element of the fuel cycle and an aggregate uncertainty analysis, (3) the inclusion of an optimization engine able to optimize simultaneously across multiple objective functions, and (4) open and accessible code software and documentation to aid in collaboration between multiple entities and facilitate software updates. Existing codes, categorized as annualized or discrete fuel tracking codes, were assessed according to the four functions and associated requirements. These codes were developed by various government, education and industrial entities to fulfill particular needs. In some cases, decisions were made during code development to limit the level of detail included in a code to ease its use or to focus on certain aspects of a fuel cycle to address specific questions. The review revealed that while no two of the codes are identical, they all perform many of the same basic functions. No code was able to perform defined function 2 or several requirements of functions 1 and 3. Based on this review, it was concluded that the functions and requirements will be met only with development of a new code, referred to as GENIUS.

Jacob J. Jacobson; Mary Lou Dunzik-Gougar; Christopher A. Juchau

2010-08-01

316

Genetic Evidence for Bacterial Chemolithoautotrophy Based on the Reductive Tricarboxylic Acid Cycle in Groundwater Systems  

PubMed Central

Geologically and chemically distinct aquifers were screened for the presence of two genes coding for key enzymes of the reverse tricarboxylic acid (rTCA) cycle in autotrophic bacteria, 2-oxoglutarate : ferredoxin oxidoreductase (oorA) and the beta subunit of ATP citrate lyase enzymes (aclB). From 42 samples investigated, aclB genes were detected in two and oorA genes in six samples retrieved from polluted and sulfidic aquifers. aclB genes were represented by a single phylotype of almost identical sequences closely affiliated with chemolithoautotrophic Sulfurimonas species. In contrast, sequences analysis of oorA genes revealed diverse phylotypes mainly related to sequences from cultivation-independent studies. PMID:22791056

Alfreider, Albin; Vogt, Carsten

2012-01-01

317

Module structure of interphotoreceptor retinoid-binding protein (IRBP) may provide bases for its complex role in the visual cycle – structure/function study of Xenopus IRBP  

PubMed Central

Background Interphotoreceptor retinoid-binding protein's (IRBP) remarkable module structure may be critical to its role in mediating the transport of all-trans and 11-cis retinol, and 11-cis retinal between rods, cones, RPE and Müller cells during the visual cycle. We isolated cDNAs for Xenopus IRBP, and expressed and purified its individual modules, module combinations, and the full-length polypeptide. Binding of all-trans retinol, 11-cis retinal and 9-(9-anthroyloxy) stearic acid were characterized by fluorescence spectroscopy monitoring ligand-fluorescence enhancement, quenching of endogenous protein fluorescence, and energy transfer. Finally, the X-ray crystal structure of module-2 was used to predict the location of the ligand-binding sites, and compare their structures among modules using homology modeling. Results The full-length Xenopus IRBP cDNA codes for a polypeptide of 1,197 amino acid residues beginning with a signal peptide followed by four homologous modules each ~300 amino acid residues in length. Modules 1 and 3 are more closely related to each other than either is to modules 2 and 4. Modules 1 and 4 are most similar to the N- and C-terminal modules of the two module IRBP of teleosts. Our data are consistent with the model that vertebrate IRBPs arose through two genetic duplication events, but that the middle two modules were lost during the evolution of the ray finned fish. The sequence of the expressed full-length IRBP was confirmed by liquid chromatography-tandem mass spectrometry. The recombinant full-length Xenopus IRBP bound all-trans retinol and 11-cis retinaldehyde at 3 to 4 sites with Kd's of 0.2 to 0.3 ?M, and was active in protecting all-trans retinol from degradation. Module 2 showed selectivity for all-trans retinol over 11-cis retinaldehyde. The binding data are correlated to the results of docking of all-trans-retinol to the crystal structure of Xenopus module 2 suggesting two ligand-binding sites. However, homology modeling of modules 1, 3 and 4 indicate that both sites may not be available for binding of ligands in all four modules. Conclusion Although its four modules are homologous and each capable of supporting ligand-binding activity, structural differences between their ligand-binding domains, and interactions between the modules themselves will be critical to understanding IRBP's complex role in the visual cycle. PMID:17683573

Gonzalez-Fernandez, Federico; Baer, Claxton A; Ghosh, Debashis

2007-01-01

318

Anti cancer effects of curcumin: cycle of life and death  

Microsoft Academic Search

Increasing knowledge on the cell cycle deregulations in cancers has promoted the introduction of phytochemicals, which can either modulate signaling pathways leading to cell cycle regulation or directly alter cell cycle regulatory molecules, in cancer therapy. Most human malignancies are driven by chromosomal translocations or other genetic alterations that directly affect the function of critical cell cycle proteins such as

Gaurisankar Sa; Tanya Das

2008-01-01

319

The Water Cycle  

NSDL National Science Digital Library

Students will learn the process of the water cycle. Alabama Course of Study: Science. Second Grade: Standard 9: Describe evaporation, condensation, and precipitation in the water cycle. What is the water cycle? On the worksheet provided, list the 4 parts of the water cycle. Between the parts draw a small picture to represent what is happening during this cycle. The Water Cycle See how we use the water in the water cycle. Thirstins Water Cycle Name 3 ways water changes form. This is an animated diagram of the Water Cycle Here is a ...

Mrs. Lopez

2009-07-09

320

THE WATER CYCLE/ CLOUDS  

NSDL National Science Digital Library

Students will learn about the water cycle and how it works. You will explore many resources to find out many new factors about the water cycle. What is the water cycle? National water cycle Name the 4 water parts of the water cycle? Weather wonders Where are 3 places that the water cycle exists- What happens after condensation? animated water cycle Name 4 types of clouds? What is the highest level cloud called? Which cloud is associated with powerful thunderstorms? Cloud Types What do clouds have to do with the water cycle? National water cycle What is ...

Ms.Brown

2009-04-06

321

The influence of tumor necrosis factor ? (TNF) on the secretory function of bovine corpus luteum: TNF and its receptors expression during the estrous cycle  

Microsoft Academic Search

SUMMARY Tumor necrosis factor ? (TNF) inversely regulates the function of bovine corpus luteum (CL). Whereas the low doses of TNF induce luteolysis, the high doses prolong CL lifespan and prevent luteolysis in vivo. We suggest that the varying effects of TNF may be caused by its action exerted on CL via multiple signaling pathways involving two distinct receptors: TNFR-I

Anna Korzekwa; Shuko Murakami; Izabela Woc?awek-Potocka; Mamadou M. Bah; Kiyoshi Okuda; Dariusz J. Skarzynski

322

INCUBATION TEMPERATURE AND EGGSHELL CONDUCTANCE EFFECTS ON THE INTESTINAL MATURATION AND THYROID FUNCTION IN COMMERCIAL TURKEY POULTS HATCHING FROM THE FIRST CYCLE FLOCK  

Technology Transfer Automated Retrieval System (TEKTRAN)

Eggshell conductance (G) and egg white (EW) affect poult viability. Poor livability may be related intestinal maturation and thyroid function of the neonate. The objectives of this study were to test if incubator temperature and G determine poult maturity among egg from a young turkey flock. Matu...

323

Limb-bud and Heart (LBH) Functions as a Tumor Suppressor of Nasopharyngeal Carcinoma by Inducing G1/S Cell Cycle Arrest  

PubMed Central

Epstein–Barr virus-encoded latent membrane protein-1 (LMP1) plays a fundamental role in the malignant transformation of nasopharyngeal carcinoma (NPC), although the mechanism is not well understood. Here, we showed that Limb-bud and Heart (LBH) is considerably downregulated in patient NPC tissues. The expression of LBH in biopsies of 40 consecutive NPC patients devoid of initial distant metastasis and treated according to consistent guidelines was also analyzed, and we found the LBH expression level was correlated with some of clinicopathological features, disease-specific survival (DSS), distant metastasis-free survival (DMFS). We further determined that LBH normally induces NPC cell cycle arrest at the G1/S transition, and LBH can suppress the growth of transplanted NPC tumors in vivo by downregulating LMP1-mediated NF-?B transcriptional activity. Transforming growth factor-beta 1 (TGF-?1) normally protects against tumor development by suppressing cell proliferation, but NPC cells acquire resistance to TGF-?1–mediated inhibition. We found that TGF-?1 inhibits NF-?B transcriptional activity and nasopharyngeal epithelial cell proliferation through upregulating LBH expression. These data reveal a previously unknown NPC transformation mechanism and provide a new concept and treatment strategy for LMP1-driven oncogenesis in NPC. PMID:25557837

Liu, Qicai; Guan, Xiaoying; Lv, Jingli; Li, Xiaoyan; Wang, Yingfeng; Li, Li

2015-01-01

324

Discovering the Water Cycle!  

NSDL National Science Digital Library

We will be learning about what the water cycle is and how it works. Resources! The Hydrologic Cycle: Water's journey through time The Water Cycle Thirstin's Water Cycle Activity Water evaporates from the surface Water Wonders These are a collection of websites that are going to help us in our journey of discovering what the water cycle is. ...

Miss Mortensen

2009-10-09

325

Classification of a frameshift/extended and a stop mutation in WT1 as gain-of-function mutations that activate cell cycle genes and promote Wilms tumour cell proliferation  

PubMed Central

The WT1 gene encodes a zinc finger transcription factor important for normal kidney development. WT1 is a suppressor for Wilms tumour development and an oncogene for diverse malignant tumours. We recently established cell lines from primary Wilms tumours with different WT1 mutations. To investigate the function of mutant WT1 proteins, we performed WT1 knockdown experiments in cell lines with a frameshift/extension (p.V432fsX87 = Wilms3) and a stop mutation (p.P362X = Wilms2) of WT1, followed by genome-wide gene expression analysis. We also expressed wild-type and mutant WT1 proteins in human mesenchymal stem cells and established gene expression profiles. A detailed analysis of gene expression data enabled us to classify the WT1 mutations as gain-of-function mutations. The mutant WT1Wilms2 and WT1Wilms3 proteins acquired an ability to modulate the expression of a highly significant number of genes from the G2/M phase of the cell cycle, and WT1 knockdown experiments showed that they are required for Wilms tumour cell proliferation. p53 negatively regulates the activity of a large number of these genes that are also part of a core proliferation cluster in diverse human cancers. Our data strongly suggest that mutant WT1 proteins facilitate expression of these cell cycle genes by antagonizing transcriptional repression mediated by p53. We show that mutant WT1 can physically interact with p53. Together the findings show for the first time that mutant WT1 proteins have a gain-of-function and act as oncogenes for Wilms tumour development by regulating Wilms tumour cell proliferation. PMID:24619359

Busch, Maike; Schwindt, Heinrich; Brandt, Artur; Beier, Manfred; Görldt, Nicole; Romaniuk, Paul; Toska, Eneda; Roberts, Stefan; Royer, Hans-Dieter; Royer-Pokora, Brigitte

2014-01-01

326

Increased tricarboxylic acid cycle flux in rat brain during forepaw stimulation detected with 1H[13C]NMR.  

PubMed Central

NMR spectroscopy was used to test recent proposals that the additional energy required for brain activation is provided through nonoxidative glycolysis. Using localized NMR spectroscopic methods, the rate of C4-glutamate isotopic turnover from infused [1-(13)C]glucose was measured in the somatosensory cortex of rat brain both at rest and during forepaw stimulation. Analysis of the glutamate turnover data using a mathematical model of cerebral glucose metabolism showed that the tricarboxylic acid cycle flux [(V(TCA)] increased from 0.49 +/- 0.03 at rest to 1.48 +/- 0.82 micromol/g/min during stimulation (P < 0.01). The minimum fraction of C4-glutamate derived from C1-glucose was approximately 75%, and this fraction was found in both the resting and stimulated rats. Hence, the percentage increase in oxidative cerebral metabolic rate of glucose use (CMRglc) equals the percentage increases in V(TCA) and cerebral metabolic rate of oxygen consumption (CMRO2). Comparison with previous work for the same rat model, which measured total CMRglc [Ueki, M., Linn, F. & Hossman, K. A. (1988) J. Cereb. Blood Flow Metab. 8, 486-4941, indicates that oxidative CMRglc supplies the majority of energy during sustained brain activation. Images Fig. 2 PMID:8755523

Hyder, F; Chase, J R; Behar, K L; Mason, G F; Siddeek, M; Rothman, D L; Shulman, R G

1996-01-01

327

Functional ability of cytoskeletal ? - actin regulator to drive constitutive and ubiquitous expression of a fluorescent reporter throughout the life cycle of transgenic marine medaka Oryzias dancena  

Microsoft Academic Search

Marine medaka Oryzias dancena, a candidate model organism, represents many attractive merits as a material for experimental transgenesis and\\/or heterologous\\u000a expression assay particularly in the field of ecotoxicology and developmental biology. In this study, cytoskeletal ?-actin gene was characterized from O. dancena and the functional capability of its promoter to drive constitutive expression of foreign reporter protein was evaluated.\\u000a The

Young Sun Cho; Sang Yoon Lee; Youn Kyoung Kim; Dong Soo Kim; Yoon Kwon Nam

328

Cyclin E-CDK2 protein phosphorylates plant homeodomain finger protein 8 (PHF8) and regulates its function in the cell cycle.  

PubMed

Cyclin E-CDK2 is a key regulator in G1/S transition. Previously, we identified a number of CDK2-interacting proteins, including PHF8 (plant homeodomain finger protein 8). In this report, we confirmed that PHF8 is a novel cyclin E-CDK2 substrate. By taking the approach of mass spectrometry, we identified that PHF8 Ser-844 is phosphorylated by cyclin E-CDK2. Immunoblotting analysis indicated that WT PHF8 demethylates histone H3K9me2 more efficiently than the cyclin E-CDK2 phosphorylation-deficient PHF8-S844A mutant. Furthermore, flow cytometry analysis showed that WT PHF8 promotes S phase progression more robustly than PHF8-S844A. Real-time PCR results demonstrated that PHF8 increases transcription of cyclin E, E2F3, and E2F7 to significantly higher levels compared with PHF8-S844A. Further analysis by ChIP assay indicated that PHF8 binds to the cyclin E promoter stronger than PHF8-S844A and reduces the H3K9me2 level at the cyclin E promoter more efficiently than PHF8-S844A. In addition, we found that cyclin E-CDK2-mediated phosphorylation of PHF8 Ser-844 promotes PHF8-dependent rRNA transcription in luciferase reporter assays and real-time PCR. Taken together, these results indicate that cyclin E-CDK2 phosphorylates PHF8 to stimulate its demethylase activity to promote rRNA transcription and cell cycle progression. PMID:25548279

Sun, Liping; Huang, Yan; Wei, Qian; Tong, Xiaomei; Cai, Rong; Nalepa, Grzegorz; Ye, Xin

2015-02-13

329

Beyond genomic variation - comparison and functional annotation of three Brassica rapa genomes: a turnip, a rapid cycling and a Chinese cabbage  

PubMed Central

Background Brassica rapa is an economically important crop species. During its long breeding history, a large number of morphotypes have been generated, including leafy vegetables such as Chinese cabbage and pakchoi, turnip tuber crops and oil crops. Results To investigate the genetic variation underlying this morphological variation, we re-sequenced, assembled and annotated the genomes of two B. rapa subspecies, turnip crops (turnip) and a rapid cycling. We then analysed the two resulting genomes together with the Chinese cabbage Chiifu reference genome to obtain an impression of the B. rapa pan-genome. The number of genes with protein-coding changes between the three genotypes was lower than that among different accessions of Arabidopsis thaliana, which can be explained by the smaller effective population size of B. rapa due to its domestication. Based on orthology to a number of non-brassica species, we estimated the date of divergence among the three B. rapa morphotypes at approximately 250,000 YA, far predating Brassica domestication (5,000-10,000 YA). Conclusions By analysing genes unique to turnip we found evidence for copy number differences in peroxidases, pointing to a role for the phenylpropanoid biosynthesis pathway in the generation of morphological variation. The estimated date of divergence among three B. rapa morphotypes implies that prior to domestication there was already considerably divergence among B. rapa genotypes. Our study thus provides two new B. rapa reference genomes, delivers a set of computer tools to analyse the resulting pan-genome and uses these to shed light on genetic drivers behind the rich morphological variation found in B. rapa. PMID:24684742

2014-01-01

330

In vivo effects of the soluble fraction of light cycle oil on immune functions in the European sea bass, Dicentrarchus labrax (Linné).  

PubMed

Hydrocarbons are major contaminants that may affect biota at various trophic levels in estuaries and coastal ecosystems. The effects of accidental pollution by light cycle oil (LCO), a refined product of heavy fuel oil, on bioaccumulation, depuration processes and immune-related parameters in the European sea bass, Dicentrarchus labrax, were investigated in the laboratory after 7 days of exposure and a 2-week recovery period. Exposure of fish to the soluble fraction of LCO (1600ngL(-1)) for 7 days led to the bioaccumulation of some polycyclic aromatic hydrocarbons (PAHs) in muscles: naphthalene, acenaphthene, fluorene, phenanthrene and anthracene. After 7 days of recovery period, half-elimination of naphthalene was reported in fish muscles due to facilitated diffusive loss by the epithelium and a faster elimination rate proven by the presence of a high level of naphthalene biliary metabolites. The other bioaccumulated molecules displayed a slower depuration rate due to their elimination by the formation of hydrophobic metabolites excreted through bile or urine. Three days after the beginning of the recovery period, each contaminated fish showed severe external lesions (tissue necrosis, suppurative exudates, haemorrhagic area). The hypothesis of a possible link with inflammatory phenomenon was supported by (i) an inversion of the leucocyte sub-population percentage, (ii) a significant up-expression in the spleen of the tumour necrosis factor alpha gene, (iii) a significant increase in ACH(50). Moreover, the lack of C3 gene regulation in the spleen suggested a non-renewal of this component. The reduction of phagocytic activity and lysozyme concentration reflected immune suppression. Finally, LCO toxicity in this fish was clearly demonstrated to be related to inflammatory reaction and immune depletion. PMID:21764455

Bado-Nilles, Anne; Quentel, Claire; Mazurais, David; Zambonino-Infante, José Luis; Auffret, Michel; Thomas-Guyon, Hélène; Le Floch, Stéphane

2011-10-01

331

Vps10p cycles between the late-Golgi and prevacuolar compartments in its function as the sorting receptor for multiple yeast vacuolar hydrolases  

PubMed Central

VPS10 (Vacuolar Protein Sorting) encodes a large type I transmembrane protein (Vps10p), involved in the sorting of the soluble vacuolar hydrolase carboxypeptidase Y (CPY) to the Saccharomyces cerevisiae lysosome-like vacuole. Cells lacking Vps10p missorted greater than 90% CPY and 50% of another vacuolar hydrolase, PrA, to the cell surface. In vitro equilibrium binding studies established that the 1,380-amino acid lumenal domain of Vps10p binds CPY precursor in a 1:1 stoichiometry, further supporting the assignment of Vps10p as the CPY sorting receptor. Vps10p has been immunolocalized to the late-Golgi compartment where CPY is sorted away from the secretory pathway. Vps10p is synthesized at a rate 20-fold lower that that of its ligand CPY, which in light of the 1:1 binding stoichiometry, requires that Vps10p must recycle and perform multiple rounds of CPY sorting. The 164-amino acid Vps10p cytosolic domain is involved in receptor trafficking, as deletion of this domain resulted in delivery of the mutant Vps10p to the vacuole, the default destination for membrane proteins in yeast. A tyrosine-based signal (YSSL80) within the cytosolic domain enables Vps10p to cycle between the late-Golgi and prevacuolar/endosomal compartments. This tyrosine-based signal is homologous to the recycling signal of the mammalian mannose-6-phosphate receptor. A second yeast gene, VTH2, encodes a protein highly homologous to Vps10p which, when over-produced, is capable of suppressing the CPY and PrA missorting defects of a vps10 delta strain. These results indicate that a family of related receptors act to target soluble hydrolases to the vacuole. PMID:8636229

1996-01-01

332

Carbon cycling and carbon metabolism by soil fungi in a boreal forest: impacts of wildfire and permafrost on functional genes, isotope signatures, and ectomycorrhizae  

NASA Astrophysics Data System (ADS)

Understanding the mechanisms that control the stabilization and destabilization of soil carbon within boreal forest ecosystems is of great importance to the global carbon budget. Much is currently known about boreal soil carbon dynamics in relation to biophysical and landscape variables such as temperature, moisture, wildfire intensity, and stand age. We have less information regarding the controls on decomposition at the molecular scale, where interactions between microbial communities, their genetic `potential' for decomposition, functional genes, enzyme synthesis, and organic matter transformations occur. We have entered an age in which these connections can be made at the molecular scale, but what form do they take, and can they scale up to affect carbon dynamics at the level of the ecosystem? We examined these molecular scale processes in mature boreal forest soils and soils that had been impacted by wildfire near Delta Junction, Alaska. We also examined the interactive effect of permafrost presence, which reduces soil drainage, with wildfire. We focused on three themes: linking microbial communities and laccase functional genes to soil laccase enzyme activity and lignin decomposition, assessing substrate availability using the natural abundance ?13C isotope ratios of microbial biomass, and the influence of ectomycorrhizal mats on decomposition. Wildfire reduced fungal biomass, laccase functional gene abundance, laccase activity, and ?13C-lignin decomposition. Relationships between gene abundance and microbial activity were significant and logarithmic in form. Soil drainage, which is mediated by the presence of permafrost, had little effect on the abundance of fungi, functional genes, or potential process rates. Microbial biomass ?13C was always enriched relative to soil organic matter, and this difference was greater in control soils compared to wildfire-affected soils, indicating that Ä??13C MB-SOIL may indicate the level of bioavailability of soil carbon for microbial metabolism. Ectomycorrhizal mats occurred only in control soils and increased fungal biomass, functional gene abundance, enzyme activities and process rates compared to non-mat soils. Taken together these results indicate that linkages can be made between the distribution of soil microbial communities, molecular scale information, and soil carbon dynamics.

Waldrop, M. P.; Harden, J. W.

2006-12-01

333

Urinary loss of tricarboxylic acid cycle intermediates as revealed by metabolomics studies: an underlying mechanism to reduce lipid accretion by whey protein ingestion?  

PubMed

Whey protein intake is associated with the modulation of energy metabolism and altered body composition both in human subjects and in animals, but the underlying mechanisms are not yet elucidated. We fed obesity-prone C57BL/6J mice high-fat diets with either casein (HF casein) or whey (HF whey) for 6 weeks. At equal energy intake and apparent fat and nitrogen digestibility, mice fed HF whey stored less energy as lipids, evident both as lower white adipose tissue mass and as reduced liver lipids, compared with HF-casein-fed mice. Explorative analyses of 48 h urine, both by (1)H NMR and LC-MS metabolomic platforms, demonstrated higher urinary excretion of tricarboxylic acid (TCA) cycle intermediates citric acid and succinic acid (identified by both platforms), and cis-aconitic acid and isocitric acid (identified by LC-MS platform) in the HF whey, relative to in the HF-casein-fed mice. Targeted LC-MS analyses revealed higher citric acid and cis-aconitic acid concentrations in fed state plasma, but not in liver of HF-whey-fed mice. We propose that enhanced urinary loss of TCA cycle metabolites drain available substrates for anabolic processes, such as lipogenesis, thereby leading to reduced lipid accretion in HF-whey-fed compared to HF-casein-fed mice. PMID:24702026

Lillefosse, Haldis H; Clausen, Morten R; Yde, Christian C; Ditlev, Ditte B; Zhang, Xumin; Du, Zhen-Yu; Bertram, Hanne C; Madsen, Lise; Kristiansen, Karsten; Liaset, Bjørn

2014-05-01

334

A Functional Calvin Cycle Is Not Indispensable for the Light Activation of C4 Phosphoenolpyruvate Carboxylase Kinase and Its Target Enzyme in the Maize Mutant bundle sheath defective2-mutable11  

PubMed Central

We used a pale-green maize (Zea mays L.) mutant that fails to accumulate ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) to test the working hypothesis that the regulatory phosphorylation of C4 phosphoenolpyruvate carboxylase (PEPC) by its Ca2+-insensitive protein-serine/threonine kinase (PEPC kinase) in the C4 mesophyll cytosol depends on cross-talk with a functional Calvin cycle in the bundle sheath. Wild-type (W22) and bundle sheath defective2-mutable1 (bsd2-m1) seeds were grown in a controlled environment chamber at 100 to 130 ?mol m?2 s?1 photosynthetic photon flux density, and leaf tissue was harvested 11 d after sowing, following exposure to various light intensities. Immunoblot analysis showed no major difference in the amount of polypeptide present for several mesophyll- and bundle-sheath-specific photosynthetic enzymes apart from Rubisco, which was either completely absent or very much reduced in the mutant. Similarly, leaf net CO2-exchange analysis and in vitro radiometric Rubisco assays showed that no appreciable carbon fixation was occurring in the mutant. In contrast, the sensitivity of PEPC to malate inhibition in bsd2-m1 leaves decreased significantly with an increase in light intensity, and there was a concomitant increase in PEPC kinase activity, similar to that seen in wild-type leaf tissue. Thus, although bsd2-m1 mutant plants lack an operative Calvin cycle, light activation of PEPC kinase and its target enzyme are not grossly perturbed. PMID:9733538

Smith, Lucy H.; Langdale, Jane A.; Chollet, Raymond

1998-01-01

335

Antiproliferative activity of the isoindigo 5'-Br in HL-60 cells is mediated by apoptosis, dysregulation of mitochondrial functions and arresting cell cycle at G0/G1 phase.  

PubMed

Our new compound, 5'-Br [(E)-1-(5'-bromo-2'-oxoindolin-3'-ylidene)-6-ethyl-2,3,6,9-tetrahydro-2,9-dioxo-1H-pyrrolo[3,2-f]quinoline-8-carboxylic acid], had shown strong, selective antiproliferative activity against different cancer cell lines. Here, we aim to comprehensively characterize the mechanisms associated with its cytotoxicity in the human promyelocytic leukemia HL-60 cells. We focused at studying the involvement of apoptotic pathway and cell cycle effects. 5'-Br significantly inhibited proliferation by inducing caspase-dependent apoptosis. Involvement of caspase independent mechanism is also possible due to observed inability of z-VAD-FMK to rescue apoptotic cells. 5'-Br was found to trigger intrinsic apoptotic pathway as indicated by depolarization of the mitochondrial inner membrane, decreased level of cellular ATP, modulated expression and phosphorylation of Bcl-2 leading to loss of its association with Bax, and increased release of cytochrome c. 5'-Br treated cells were found arrested at G0/G1 phase with modulation in protein levels of cyclins, dependent kinases and their inhibitors. Expression and enzymatic activity of CDK2 and CDK4 was found inhibited. Retinoblastoma protein (Rb) phosphorylation was also inhibited whereas p21 protein levels were increased. These results suggest that the antiproliferative mechanisms of action of 5'-Br could involve apoptotic pathways, dysregulation of mitochondrial functions and disruption of cell cycle checkpoint. PMID:25790909

Saleh, Ayman M; El-Abadelah, Mustafa M; Aziz, Mohammad Azhar; Taha, Mutasem O; Nasr, Amre; Rizvi, Syed A A

2015-06-01

336

Annual Cycle of Surface Longwave Radiation  

NASA Technical Reports Server (NTRS)

The annual cycles of upward and downward longwave fluxes at the Earth s surface are investigated by use of the NASA/GEWEX Surface Radiation Budget Data Set. Because of the immense difference between the heat capacity of land and ocean, the surface of Earth is partitioned into these two categories. Principal component analysis is used to quantify the annual cycles. Over land, the first principal component describes over 95% of the variance of the annual cycle of the upward and downward longwave fluxes. Over ocean the first term describes more than 87% of these annual cycles. Empirical orthogonal functions show the corresponding geographical distributions of these cycles. Phase plane diagrams of the annual cycles of upward longwave fluxes as a function of net shortwave flux show the thermal inertia of land and ocean.

Mlynczak, Pamela E.; Smith, G. Louis; Wilber, Anne C.; Stackhouse, Paul W.

2011-01-01

337

Seasonal Nitrogen Cycles on Pluto  

NASA Technical Reports Server (NTRS)

A thermal model, developed to predict seasonal nitrogen cycles on Triton, has been modified and applied to Pluto. The model is used to calculate the partitioning of nitrogen between surface frost deposits and the atmosphere, as a function of time for various sets of input parameters.

Hansen, C. J.; Paige, D. A.

1994-01-01

338

5-AED enhances survival of irradiated mice in a G-CSF-dependent manner, stimulates innate immune cell function, reduces radiation-induced DNA damage and induces genes that modulate cell cycle progression and apoptosis.  

PubMed

The steroid androst-5-ene-3ß,17ß-diol (5-androstenediol, 5-AED) elevates circulating granulocytes and platelets in animals and humans, and enhances survival during the acute radiation syndrome (ARS) in mice and non-human primates. 5-AED promotes survival of irradiated human hematopoietic progenitors in vitro through induction of Nuclear Factor-?B (NF?B)-dependent Granulocyte Colony-Stimulating Factor (G-CSF) expression, and causes elevations of circulating G-CSF and interleukin-6 (IL-6). However, the in vivo cellular and molecular effects of 5-AED are not well understood. The aim of this study was to investigate the mechanisms of action of 5-AED administered subcutaneously (s.c.) to mice 24 h before total body ?- or X-irradiation (TBI). We used neutralizing antibodies, flow cytometric functional assays of circulating innate immune cells, analysis of expression of genes related to cell cycle progression, DNA repair and apoptosis, and assessment of DNA strand breaks with halo-comet assays. Neutralization experiments indicated endogenous G-CSF but not IL-6 was involved in survival enhancement by 5-AED. In keeping with known effects of G-CSF on the innate immune system, s.c. 5-AED stimulated phagocytosis in circulating granulocytes and oxidative burst in monocytes. 5-AED induced expression of both bax and bcl-2 in irradiated animals. Cdkn1a and ddb1, but not gadd45a expression, were upregulated by 5-AED in irradiated mice. S.c. 5-AED administration caused decreased DNA strand breaks in splenocytes from irradiated mice. Our results suggest 5-AED survival enhancement is G-CSF-dependent, and that it stimulates innate immune cell function and reduces radiation-induced DNA damage via induction of genes that modulate cell cycle progression and apoptosis. PMID:22843381

Grace, Marcy B; Singh, Vijay K; Rhee, Juong G; Jackson, William E; Kao, Tzu-Cheg; Whitnall, Mark H

2012-11-01

339

Mitochondrial metabolism of glucose and glutamine is required for intracellular growth of Toxoplasma gondii  

PubMed Central

Summary Toxoplasma gondii proliferates within host cell vacuoles where the parasite relies on host carbon and nutrients for replication. To assess how T. gondii utilizes these resources, we mapped the carbon metabolism pathways in intracellular and egressed parasite stages. We determined that intracellular T. gondii stages actively catabolize host glucose via a canonical, oxidative tricarboxylic acid (TCA) cycle, a mitochondrial pathway in which organic molecules are broken down to generate energy. These stages also catabolize glutamine via the TCA cycle and an unanticipated ?-aminobutyric acid (GABA) shunt, which generates GABA and additional molecules that enter the TCA cycle. Chemically inhibiting the TCA cycle completely prevents intracellular parasite replication. Parasites lacking the GABA shunt exhibit attenuated growth and are unable to sustain motility under nutrient-limited conditions, suggesting that GABA functions as a short-term energy reserve. Thus, T. gondii tachyzoites have metabolic flexibility that likely allows the parasite to infect diverse cell types. PMID:23159057

MacRae, James I.; Sheiner, Lilach; Nahid, Amsha; Tonkin, Christopher; Striepen, Boris; McConville, Malcolm J.

2014-01-01

340

Structural and functional characterization of a cell cycle associated HDAC1/2 complex reveals the structural basis for complex assembly and nucleosome targeting.  

PubMed

Recent proteomic studies have identified a novel histone deacetylase complex that is upregulated during mitosis and is associated with cyclin A. This complex is conserved from nematodes to man and contains histone deacetylases 1 and 2, the MIDEAS corepressor protein and a protein called DNTTIP1 whose function was hitherto poorly understood. Here, we report the structures of two domains from DNTTIP1. The amino-terminal region forms a tight dimerization domain with a novel structural fold that interacts with and mediates assembly of the HDAC1:MIDEAS complex. The carboxy-terminal domain of DNTTIP1 has a structure related to the SKI/SNO/DAC domain, despite lacking obvious sequence homology. We show that this domain in DNTTIP1 mediates interaction with both DNA and nucleosomes. Thus, DNTTIP1 acts as a dimeric chromatin binding module in the HDAC1:MIDEAS corepressor complex. PMID:25653165

Itoh, Toshimasa; Fairall, Louise; Muskett, Frederick W; Milano, Charles P; Watson, Peter J; Arnaudo, Nadia; Saleh, Almutasem; Millard, Christopher J; El-Mezgueldi, Mohammed; Martino, Fabrizio; Schwabe, John W R

2015-02-27

341

Structural and functional characterization of a cell cycle associated HDAC1/2 complex reveals the structural basis for complex assembly and nucleosome targeting  

PubMed Central

Recent proteomic studies have identified a novel histone deacetylase complex that is upregulated during mitosis and is associated with cyclin A. This complex is conserved from nematodes to man and contains histone deacetylases 1 and 2, the MIDEAS corepressor protein and a protein called DNTTIP1 whose function was hitherto poorly understood. Here, we report the structures of two domains from DNTTIP1. The amino-terminal region forms a tight dimerization domain with a novel structural fold that interacts with and mediates assembly of the HDAC1:MIDEAS complex. The carboxy-terminal domain of DNTTIP1 has a structure related to the SKI/SNO/DAC domain, despite lacking obvious sequence homology. We show that this domain in DNTTIP1 mediates interaction with both DNA and nucleosomes. Thus, DNTTIP1 acts as a dimeric chromatin binding module in the HDAC1:MIDEAS corepressor complex. PMID:25653165

Itoh, Toshimasa; Fairall, Louise; Muskett, Frederick W.; Milano, Charles P.; Watson, Peter J.; Arnaudo, Nadia; Saleh, Almutasem; Millard, Christopher J.; El-Mezgueldi, Mohammed; Martino, Fabrizio; Schwabe, John W.R.

2015-01-01

342

Complexation behavior of trivalent actinides and lanthanides with 1,10-phenanthroline-2,9-dicarboxylic acid based ligands: insight from density functional theory.  

PubMed

We have investigated the complexation behavior of preorganized 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) based ligands with trivalent lanthanides and actinides using density functional theory with various GGA type exchange-correlation functionals and different basis sets. New ligands have been designed from PDA through functionalization with soft donor atoms such as sulfur, resulting in mono-thio-dicarboxylic acids (TCA/TCA1) and di-thio-dicarboxylic acid (THIO). It has been found that selectivity in terms of complexation energy of actinides over lanthanides is the maximum with TCA1 where the metal-ligand binding is through the O atoms. This unusual feature where a softer actinide metal ion is bonded strongly with hard donor oxygen atoms has been explained using the popular chemical concepts, viz., Pearson's Hard-Soft-Acid-Base (HSAB) principle and the frontier orbital theory of chemical reactivity as proposed by Fukui. Detailed analysis within the framework of the HSAB principle indicates that the presence of softer nitrogen atoms in the phenanthroline moiety (which also act as donors to the metal ion) has a profound influence in changing the soft nature of the actinide ion, which in turn binds with the hard oxygen atoms in a stronger way as compared to the valence isoelectronic lanthanide ion. Also, the trends in the variation of calculated values of the metal-ligand bond distances and the corresponding complex formation energies have been rationalized using the Fukui reactivity indices corresponding to the metal ions and the donor sites. All the calculations have also been done in the presence of solvent. The "intra-ligand synergistic effect" demonstrated here for PDA or TCA1 with soft and hard donor centers might be very important in designing new ligands for selective extraction of various metal ions in a competitive environment. However, for TCA and THIO ligands with only soft donor centers, "intra-ligand synergism" may not be very efficient although reports are available demonstrating soft-soft inter-ligand synergism. Nevertheless, in the case of TCA and THIO complexes, a shorter Am-S bond distance in conjunction with lower metal ion charge and a higher percentage of orbital interaction energy corroborate the presence of a higher degree of covalency in Am-S bonds, which in turn may be responsible for selectivity towards Am(3+). PMID:22763671

Manna, Debashree; Ghanty, Tapan K

2012-08-21

343

Trainings- and Measurement System for FES- Cycling  

Microsoft Academic Search

Due to Functional Electrical Stimulation (FES) of lower limb muscles persons with complete or incomplete paraplegia can perform a cycling movement. To quantify the progress of therapy and rehabilitation it is helpful to examine the induced forces during pedalling and the development of these forces over the period of rehabilita- tion. Therefore a trainings- and measurement- system for FES- cycling

W. Reichenfelser; H. Hackl; S. Mina; S. Hanke; P. Lugner; M. Gföhler

344

The optimization of Stirling cycle machines  

Microsoft Academic Search

The problem of numerical optimization of Stirling cycle machines is discussed and applied to the optimization of a one kW free piston Stirling engine. Stirling cycle simulation programs at the heart of the analysis are outlined with emphasis on noteworthy computational features and adaptations peculiar to free piston design. A function minimization algorithm is presented which overcomes many inadequacies of

D. R. Gedeon

1978-01-01

345

The Water Cycle  

NSDL National Science Digital Library

Today you will explore the water cycle. Please visit the following websites (in order!) to gather information about the water cycle. Fill out your Information Sheet as you go. 1. Water cycle story 2. Water Cycle--heat 3. animation (Make sure to read the captions at the bottom!) ...

Mrs. Hauck

2006-08-26

346

The Water Cycle  

NSDL National Science Digital Library

Students will understand and explain parts of the water cycle. First watch the video to get a background about the water cycle: water cycle video Draw and explain the water cycle in your own words (include the terms: evaporation, condensation, precipitation, at least 3 bodies of water, the sun). Before reading the experiment record your predictions: If you put a small amount of water ...

Miss Amanda

2011-02-14

347

Photovoltaics Life Cycle Analysis  

E-print Network

1 Photovoltaics Life Cycle Analysis Vasilis Fthenakis Center of Life Cycle Analysis Earth Brookhaven National Laboratory www.clca.columbia.edu www.pv.bnl.gov #12;2 The Life Cycle of PVThe Life Cycle (air, water, solid) M, Q E PV array Photovoltaic modules Balance of System (BOS) (Inverters

348

The Solar Cycle  

E-print Network

The Solar Cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24.

Hathaway, David H

2015-01-01

349

Systems Approaches to Predict the Functions of Glycoside Hydrolases during the Life Cycle of Aspergillus niger Using Developmental Mutants ?brlA and ?flbA  

PubMed Central

Background The filamentous fungus Aspergillus niger encounters carbon starvation in nature as well as during industrial fermentations. In response, regulatory networks initiate and control autolysis and sporulation. Carbohydrate-active enzymes play an important role in these processes, for example by modifying cell walls during spore cell wall biogenesis or in cell wall degradation connected to autolysis. Results In this study, we used developmental mutants (?flbA and ?brlA) which are characterized by an aconidial phenotype when grown on a plate, but also in bioreactor-controlled submerged cultivations during carbon starvation. By comparing the transcriptomes, proteomes, enzyme activities and the fungal cell wall compositions of a wild type A. niger strain and these developmental mutants during carbon starvation, a global overview of the function of carbohydrate-active enzymes is provided. Seven genes encoding carbohydrate-active enzymes, including cfcA, were expressed during starvation in all strains; they may encode enzymes involved in cell wall recycling. Genes expressed in the wild-type during starvation, but not in the developmental mutants are likely involved in conidiogenesis. Eighteen of such genes were identified, including characterized sporulation-specific chitinases and An15g02350, member of the recently identified carbohydrate-active enzyme family AA11. Eight of the eighteen genes were also expressed, independent of FlbA or BrlA, in vegetative mycelium, indicating that they also have a role during vegetative growth. The ?flbA strain had a reduced specific growth rate, an increased chitin content of the cell wall and specific expression of genes that are induced in response to cell wall stress, indicating that integrity of the cell wall of strain ?flbA is reduced. Conclusion The combination of the developmental mutants ?flbA and ?brlA resulted in the identification of enzymes involved in cell wall recycling and sporulation-specific cell wall modification, which contributes to understanding cell wall remodeling mechanisms during development. PMID:25629352

van Munster, Jolanda M.; Nitsche, Benjamin M.; Akeroyd, Michiel; Dijkhuizen, Lubbert; van der Maarel, Marc J. E. C.; Ram, Arthur F. J.

2015-01-01

350

The centriole duplication cycle.  

PubMed

Centrosomes are the main microtubule-organizing centre of animal cells and are important for many critical cellular and developmental processes from cell polarization to cell division. At the core of the centrosome are centrioles, which recruit pericentriolar material to form the centrosome and act as basal bodies to nucleate formation of cilia and flagella. Defects in centriole structure, function and number are associated with a variety of human diseases, including cancer, brain diseases and ciliopathies. In this review, we discuss recent advances in our understanding of how new centrioles are assembled and how centriole number is controlled. We propose a general model for centriole duplication control in which cooperative binding of duplication factors defines a centriole 'origin of duplication' that initiates duplication, and passage through mitosis effects changes that license the centriole for a new round of duplication in the next cell cycle. We also focus on variations on the general theme in which many centrioles are created in a single cell cycle, including the specialized structures associated with these variations, the deuterosome in animal cells and the blepharoplast in lower plant cells. PMID:25047614

F?rat-Karalar, Elif Nur; Stearns, Tim

2014-09-01

351

Biogeochemical cycling and remote sensing  

NASA Technical Reports Server (NTRS)

The present investigation is concerned with the role of remote sensing in the analysis of biochemical cycling. A general review is provided of the interest of NASA in biochemical cycling, taking into account an assessment of the state and dynamics of the pools and fluxes of four major elements (carbon, nitrogen, phosphorus, sulfur), an understanding of the coupling and interaction of the biosphere and the atmosphere, and an understanding of the biosphere and the oceans. Attention is given to biogeochemical cycling science issues, the potential remote sensing role, the vegetation type, aspects of vegetation structure, the leaf area index, the canopy height, functional relationships, environmental and soil variables, questions of experimental design, sampling sites and ground data, and radiometric data and analysis.

Peterson, D. L.; Mouat, D. A.

1984-01-01

352

Oxygenated monoterpenes citral and carvacrol cause oxidative damage in Escherichia coli without the involvement of tricarboxylic acid cycle and Fenton reaction.  

PubMed

Oxygenated monoterpenes citral and carvacrol are common constituents of many essential oils (EOs) that have been extensively studied as antimicrobial agents but whose mechanisms of microbial inactivation have not been totally elucidated. A recent study described a mechanism of Escherichia coli death for (+)-limonene, a hydrocarbon monoterpene also frequently present in EOs, similar to the common mechanism proposed for bactericidal antibiotics. This mechanism involves the formation of Fenton-mediated hydroxyl radical, a reactive oxygen species (ROS), via tricarboxylic acid (TCA) cycle, which would ultimately inactivate cells. Our objective was to determine whether E. coli MG1655 inactivation by citral and carvacrol follows a similar mechanism of cell death. Challenging experiments with 300?L/L citral and 100?L/L carvacrol inactivated at least 2.5log10cycles of exponentially growing cells in 3h under aerobic conditions. The presence of thiourea (an ROS scavenger) reduced cell inactivation in 2log10cycles, demonstrating the role of ROS in cell death. Decreased resistance of a ?recA mutant (deficient in an enzyme involved in SOS response to DNA damage) indicated that citral and carvacrol caused oxidative damage to DNA. Although the mechanism of E. coli inactivation by carvacrol and citral was similarly mediated by ROS, their formation did not follow the same pathways described for (+)-limonene and bactericidal drugs because neither Fenton reaction nor NADH production via the TCA cycle was involved in cell death. Moreover, further experiments demonstrated antimicrobial activity of citral and carvacrol in anaerobic environments without the involvement of ROS. As a consequence, cell death by carvacrol and citral in anaerobiosis follows a different mechanism than that observed under aerobic conditions. These results demonstrated a different mechanism of inactivation by citral and carvacrol with regard to (+)-limonene and bactericidal antibiotics, indicating the complexity of the mechanisms of bacterial inactivation among EO constituents. Advancements in the description of these mechanisms will help in extending and improving the use of these compounds as natural antimicrobials. PMID:25146464

Chueca, Beatriz; Pagán, Rafael; García-Gonzalo, Diego

2014-10-17

353

Studies on the cycle life of commercial lithium ion batteries during rapid charge–discharge cycling  

Microsoft Academic Search

The impedance spectra of Li-ion batteries as a function of the number of charge–discharge cycles have been measured to study the cycle life of the commercial Li-ion battery (prismatic Sanyo UF653467) during cycling at 1C charge–discharge rate. The individual electrodes in the batteries have been examined using XRD, transmission electron microscopy (TEM) and SEM. The results show that the Nyquist

J Li; E Murphy; J Winnick; P. A Kohl

2001-01-01

354

Rock Cycle Animation  

NSDL National Science Digital Library

Use this interactive rock cycle animation to help you with your schoolwork! This cutaway view of Earth shows where some common rock-forming processes occur. Embedded animations will illustrate the path of a rock moving through the rock cycle.

2010-01-01

355

Amazon Water Cycle Roleplay  

NSDL National Science Digital Library

In this creative roleplay activity, learners will explore the various processes of the water cycle using movement, sound, and props to aid in comprehension. Learners will understand that water changes forms throughout the water cycle, and that this cycle runs continuously throughout all the cycles at the same time. This standards-based lesson, which is great for the classroom, camps, or afterschool programs, includes roleplay cards and ideas for props.

2012-06-26

356

Water Cycle Webquest  

NSDL National Science Digital Library

Students are introduced to the Global Precipitation Measurement (GPM) satellite mission and its role in studying the water cycle. This webquest provides links to eight websites, allowing middle school students to explore the water cycle and its impacts on Earth's weather and climate. Through online videos and articles, students follow a water molecule through the cycle, discover the connection between the water cycle and global water/heat distribution, examine the role of solar energy, and assess the importance of fresh water.

357

The Water Cycle  

NSDL National Science Digital Library

This demonstration introduces the concept of water phases and cycling to younger students through observation, drawing, and writing. They will be able to explain how the Earth's water supply is recycled, form a hypothesis as to how/why the water cycle works, and use writing and drawing to explain how the cycle works.

1998-01-01

358

The Water Cycle  

NSDL National Science Digital Library

What happens in each stage of the water cycle? First, watch this video to learn about each stage of the water cycle. video Next, click on this link to read more facts about each stages of the water cycle.

Ms. Baker

2011-04-18

359

The Carbon Cycle  

NSDL National Science Digital Library

This module covers the basics of the carbon cycle and research efforts that aim to integrate ecology and the earth sciences, and describes new methodologies being developed to explore the carbon cycle. The module is divided into the following sections: Overview, Exchanges between Reservoirs, Feedbacks in the Carbon Cycle, Implications for Global Climate, Questions and Discussion Topics, Glossary, and Suggested Reading.

Elizabeth Sulzman

360

Discover the Water Cycle!  

NSDL National Science Digital Library

This interactive tour of the water cycle allows students to follow a water molecule from a home's plumbing system as it follows different routes through the hydrologic cycle. Students learn about how water is used, treated, and returned to the natural environment where it can cycle through liquid, solid, and gas phases.

361

Animating the Carbon Cycle Oswald J. Schmitz,1  

E-print Network

Animating the Carbon Cycle Oswald J. Schmitz,1 * Peter A. Raymond,1 James A. Estes,2 Werner A. Kurz, USA ABSTRACT Understanding the biogeochemical processes reg- ulating carbon cycling is central'' the carbon cycle requires broader consideration of the functional role of animals in mediating biogeochemical

Wilmers, Chris

362

[Cyclic psychosis associated with the menstrual cycle].  

PubMed

Cyclic psychosis associated with the menstrual cycle is an uncommon disorder, not included under the accepted definitions of functional psychoses. We present three female adolescents who developed an acute psychosis a few days before menstruation, which resolved completely upon bleeding or several days later, only to reappear in the same form in subsequent cycles. The clinical presentation was not in line with that of the typical functional psychoses. An extensive medical work-up did not show any significant disturbances, with the exception of anovulatory cycles in one youngster. Psychotropic treatment had no effect on the course of the psychosis. Treatment with progesterone in the second half of the cycle in one case, and with a combined progesterone/estrogen contraceptive agent in another, resulted in full recovery within several cycles. The third girl showed a spontaneous remission within four cycles. Remission continued in all cases after discontinuation of the hormonal treatment, and with no need to reintroduce any psychotropic agent, for a period of 2-4 years. We discuss several possible etiologic mechanisms for cyclic psychosis associated with the menstrual cycle, including it being a cycloid non-specific affective disorder, and its association with a temporary functional hypothalamic-pituitary dysfunction, and with anovulation. We also discuss the role of psychotropic and hormonal treatment in this disorder. PMID:12908384

Stein, D; Blumenshon, R; Hanukoglu, A; Witztum, E

2003-07-01

363

The microbial cell cycle  

SciTech Connect

This book concentrates on the major problems of cell cycle control in microorganisms. A wide variety of microorganisms, ranging from bacteria and yeasts to hyphal fungi, algae, and ciliates are analyzed, with emphasis on the basic similarities among the organisms. Different ways of looking at cell cycle control which emphasize aspects of the problem such as circadian rhythms, limit cycle oscillators, and cell size models, are considered. New approaches such as the study of cell cycle mutants, and cloning of cell cycle control genes are also presented.

Nurse, P.; Streiblova, E.

1984-01-01

364

Impaired barrier function by dietary fructo-oligosaccharides (FOS) in rats is accompanied by increased colonic mitochondrial gene expression  

PubMed Central

Background Dietary non-digestible carbohydrates stimulate the gut microflora and are therefore presumed to improve host resistance to intestinal infections. However, several strictly controlled rat infection studies showed that non-digestible fructo-oligosaccharides (FOS) increase, rather than decrease, translocation of Salmonella towards extra-intestinal sites. In addition, it was shown that FOS increases intestinal permeability already before infection. The mechanism responsible for this adverse effect of FOS is unclear. Possible explanations are altered mucosal integrity due to changes in tight junctions or changes in expression of defense molecules such as antimicrobials and mucins. To examine the mechanisms underlying weakening of the intestinal barrier by FOS, a controlled dietary intervention study was performed. Two groups of 12 rats were adapted to a diet with or without FOS. mRNA was collected from colonic mucosa and changes in gene expression were assessed for each individual rat using Agilent rat whole genome microarrays. Results Among the 997 FOS induced genes we observed less mucosal integrity related genes than expected with the clear permeability changes. FOS did not induce changes in tight junction genes and only 8 genes related to mucosal defense were induced by FOS. These small effects are unlikely the cause for the clear increase in intestinal permeability that is observed. FOS significantly increased expression of 177 mitochondria-related genes. More specifically, induced expression of genes involved in all five OXPHOS complexes and the TCA cycle was observed. These results indicate that dietary FOS influences intestinal mucosal energy metabolism. Furthermore, increased expression of 113 genes related to protein turnover, including proteasome genes, ribosomal genes and protein maturation related genes, was seen. FOS upregulated expression of the peptide hormone proglucagon gene, in agreement with previous studies, as well as three other peptide hormone genes; peptide YY, pancreatic polypeptide and cholecystokinin. Conclusion We conclude that altered energy metabolism may underly colonic barrier function disruption due to FOS feeding in rats. PMID:18371188

Rodenburg, Wendy; Keijer, Jaap; Kramer, Evelien; Vink, Carolien; van der Meer, Roelof; Bovee-Oudenhoven, Ingeborg MJ

2008-01-01

365

Trichloroacetic acid cycling in Sitka spruce saplings and effects on sapling health following long term exposure  

E-print Network

6 months of winter without dosing. No effect of TCA exposure on sapling growth was measured during effects on non-target plant species), TCA is still actively forming in the environment today). Environmental Pollution 130 (2004) 165e176 www.elsevier.com/locate/envpol 0269-7491/$ - see front matter Ó 20

Heal, Kate

366

Introduction to combined cycles  

NASA Astrophysics Data System (ADS)

Ideas and concepts underlying the technology of combined cycles including the scientific principles involved and the reasons these cycles are in fashion at the present time, are presented. A cycle is a steady flow process for conversion of heat energy into work, in which a working medium passes through a range of states, returning to its original state. Cycles for power production are the steam cycle, which is a closed cycle, and the gas turbine, which represents an open cycle. Combined cycle thermodynamic parameters, are discussed. The general arrangement of the plant is outlined and important features of their component parts described. The scope for future development is discussed. It is concluded that for the next few years the natural gas fired combined cycle will be the main type of plant installed for electricity generation and cogeneration. Whilst gas turbines may not increase substantially in unit size, there remains scope for further increase in firing temperature with consequent increase in cycle performance. However the larger global reserves of coal are providing an incentive to the development of plant for clean coal combustion using the inherent advantage of the combined cycle to attain high efficiencies.

Moore, M. J.

367

NiH2 Cycle Life Study  

NASA Technical Reports Server (NTRS)

Cycle life studies have been performed at Eagle Picher Technologies (EPT), on HST Mantech design cells with various pedigrees of slurry and dry sinter processed electrodes, to evaluate peak load voltage performance during generic load profile testing. These tests provide information for determining voltage and capacity fade (degradation) mechanisms, and their impact on nickel hydrogen cell cycle life. Comparison of peak load voltage fade, as a function of State of Charge and cycle life, with capacity data from HST indicates that the cycle life limiting mechanism is due to impedance growth, and formation of a second discharge plateau. With a second plateau on discharge, capacity from the cell is still available, but at an unacceptable low voltage of 0.8 V per cell (17.6 V battery). Data shows that cell impedance increases with cycle number and depth of discharge, as expected.

Hollandsworth, Roger P.; Armantrout, Jon D.; Rao, Gopalakrishna M.

2002-01-01

368

Thermal cycling graphite-polyimide  

NASA Technical Reports Server (NTRS)

The effects of repetitive thermal cycling on the temperature-thermal deformation relation of graphite-polyimide were determined. The bending and axial strains, measured with strain gages, of unsymmetric 0 deg sub 2/90 deg sub 2 and 0 deg sub 4/90 deg sub 4 laminates were used as an indication of thermal deformation. The strains were measured as a function of temperature and two temperature ranges were used, room temperature to 180 C and room temperature to 315 C. Five cycles were run in each temperature range and the cycling was done in quasistatic fashion. The response of a flat 0 deg sub 8 laminate was measured as were the effects of repetitive cycling on the strain gages themselves. A piece-wise linear theory, based on classical lamination theory and using the variation of mechanical and thermal expansion properties with temperature, was compared with the experimental results. The correlation between theoretical predictions and experimental results for the thinner laminate was poor.

Hyer, M. W.; Hagaman, J. A.

1979-01-01

369

Web-o-Cycles  

NSDL National Science Digital Library

Called the "Web-o-Cycles," groups of students are each assigned a different matter cycle to become deeply familiar with not only the internal components and interactions, but also possible connections to other cycles. For example, volcanic activity in the rock cycle also discharges sulfur into the atmosphere, which turn interacts with the water cycle in cloud formation. Connections such as these are made between posters of the cycles using colored yard, hooked on the appropriate nodes on each cycle and labeled by the nature of the interaction with the note cards hung on the yarn. In a short period of time, the classroom is a web of yarn, connecting each cycle to the others. The next element of this activity attempts to capture elements of complex Earth systems, especially the concepts of equilibrium, hysteresis, power law relationships, and sensitive dependence. All lines connecting the cycles are held taut, representing an equilibrium condition. Small shifts in one cycle are compensated for by consequent shifts in other cycles. Selecting one of the interconnecting strands, tension is in introduced, first in small pulls which accumulate to imbalance and shift the cycles slightly. A single large pull in one strand, to the point of breaking the yarn, causes some lines to slacken, perhaps to the point that they cannot be easily restored to tautness without dramatic shifts in the connected cycles. Re-tightening the connections causes a shift in the cycles, which takes place quickly and assumes a slightly different but at least familiar pattern. Having students then share their observations of the process of pattern description-imbalances-shifts-new equilibrium allows them to recognize the dynamic nature of Earth systems interactions as well as to seek deeper understanding of hidden elements within the Earth system. Materials needed: At least four posters depicting detailed graphical representations of matter cycles, such as water, carbon, rock, nitrogen, sulfur, phosphorous, mounted on cardboard or another rigid material. Students should have available to them information on each cycle, depicting relative volumes of material in each cycle phase, residence times of the material in those phases, and the processes that drive changes from one phase to another; At least one ball of yarn, in a different color, for each poster; Note cards on which students will write a description of the individual processes used to link cycles; Paper clips to hang the note cards on these connective strands.

Eric Pyle

370

Use of S-PolKa Particles IDentification and TMI and MADRAS brightness temperatures to characterize the ice microphysics in rain systems as a function of their life cycle.  

NASA Astrophysics Data System (ADS)

In the framework of the French-Indian Megha-Tropiques Mission, a specific campaign was dedicated to ice microphysics studies during the CYNDIE-DYNAMO experiment. This contribution consisted in deploying the French Falcon 20 from mid-November to mid-December in Gan and perform about 40 hours of microphysics flights. The Falcon was equipped with a up- and downward looking W-Band Doppler Radar (RASTA) and a series of microphysics probes in order to characterize the ice particles in terms of density. This information is of dramatic importance to the microwave-based rain retrieval algorithms and more specifically the operational algorithm used in Megha-Tropiques known as BRAIN (Viltard et al 2006, Viltard et al 2012). This algorithm uses a retrieval database to reduce the number of possible solutions to those actually physical. This requires the computation of microwave brightness temperatures through a radiative transfer model in which the ice microphysics properties are parameterized. This parametrization is key for all brightness temperature simulation above roughly 30 GHz and strongly affects the quality of the rain retrieval. For the limited number of cases when the Falcon flew, we have a rather detailed description of the ice microphysics properties but this happens to be insufficient to build a robust statistics of the ice as a function of rain system life cycle. Hence the use of particles identification (PID) obtained from the ground-based polarimetric data from NCAR SPol-Ka. This dataset covers almost 5 month within a 200 km radius centered on Gan. We will briefly present our contribution in the CYNDIE-DYNAMO campaign and interpret in terms of microphysical properties the comparisons between these PIDs and the brightness temperatures measured by two passive microwave radiometers: TMI on TRMM and MADRAS on Megha-Tropiques.

Martini, Audrey; Viltard, Nicolas

2013-04-01

371

Menstrual and lunar cycles.  

PubMed

A double-blind, prospective study during the fall of 1979 investigated the association between the menstrual cycles of 305 Brooklyn College undergraduates and their associates and the lunar cycles. All subjects were 19-35 years old and using neither OCs (oral contraceptives) nor the IUD. Approximately 1/3 of the subjects had lunar period cycles, i.e., a mean cycle length of 29.5 +/- l day. Almost 2/3 of the subjects started their October cycle in the light 1/2 of the lunar cycle, significantly more than would be expected by random distribution. The author concludes that there is a lunar influence on ovulation. PMID:7246643

Friedmann, E

1981-06-01

372

Cell Cycle Activation and Spinal Cord Injury  

Microsoft Academic Search

Summary  Traumatic spinal cord injury (SCI) evokes a complex cascade of events with initial mechanical damage leading to secondary\\u000a injury processes that contribute to further tissue loss and functional impairment. Growing evidence suggests that the cell\\u000a cycle is activated following SCI. Up-regulation of cell cycle proteins after injury appears to contribute not only to apoptotic\\u000a cell death of postmitotic cells, including

Junfang Wu; Bogdan A. Stoica; Alan I. Faden

2011-01-01

373

Carbon Cycle Roleplay  

NSDL National Science Digital Library

In this creative roleplay activity, learners will explore the various processes of the carbon cycle using movement and props to aid in comprehension. Learners will understand that carbon changes forms throughout the carbon cycle, and that carbon is continuously moving throughout all the cycles at the same time. This standards-based lesson, which is great for the classroom, camps, or afterschool programs, includes roleplay cards and ideas for props.

California Academy of Sciences

2008-01-01

374

The Water Cycle  

NSDL National Science Digital Library

This interactive diagram of the water cycle invites students to click on a part of the cycle to get information about streamflow, surface runoff, freshwater storage, ground-water discharge, ground-water storage, infiltration, precipitation, snowmelt, runoff to streams, springs, condensation, evaporation, transpiration, water in the atmosphere, ice and snow, and oceans. A summary of the water cycle on a single webpage is also available as text with pictures in about fifty languages, text only in thirteen languages, or diagram only.

2007-12-12

375

Butterfly Life Cycle  

NSDL National Science Digital Library

In this project we will be learning about the life cycle of a butterfly and how the caterpillar becomes to be a butterfly. WHAT IS THE LIFE CYCLE OF A BUTTERFLY??? Subject: Science, Grade level:3rd and 4th Grade. Objective# 5-Describing life cycles of various animals to include incomplete and complete metamorphosis. In this project, I am going to show the students what an amazing and unique tranformation the a Caterpillar goes through and ...

Katie

2009-10-22

376

Texas Rock Cycle  

NSDL National Science Digital Library

The Texas Rock Cycle is an exercise demonstrating rock transformation. Materials needed for this activity are the Texas Rock Kit and a page-size Geologic Map of Texas, each available from the publications department of the Bureau of Economic Geology. Each rock kit contains samples of calcite, quartz, feldspar, granite, basalt, sandstone, gneiss, limestone, chert, and schist. This site contains a rock cycle puzzle to print out and instructions on how to conduct a rock cycle investigation.

377

THE WATER CYCLE  

NSDL National Science Digital Library

DESK Standard: Understand the processes of evaporation, condensation, and precipitation as they relate to the water cycle. Water Cycle Diagram DATES: You can begin this activity on October 16. You should complete it by October 20. OBJECTIVE: You have been learning about the water cycle in class. This activity gives you the chance to review some important vocabulary: evaporation condensation precipitation collection You will watch a short video and complete a water ...

Mr. Hughes

2006-02-18

378

[Cycling in Zagreb].  

PubMed

Cycling in Zagreb, as means of urban transport inside and outside the city, has a bright past, hazy presence but a promising future. Every day, aggressive citizens who lack urban traffic culture mistreat many cyclists but also many pedestrians. Sedentary way of living, unhealthy eating habits and inadequate recreation would surely be reduced if Zagreb had a network of cycling tracks (190 cm) or lanes (80 cm). Main city roads were constructed at the beginning of the 20th century. Today, the lack of cycling tracks is particularly evident in terms of missing connections between northern and southern parts of the city. Transportation of bikes in public vehicles, parking of bikes as well as cycling along the foot of the mountains Medvednica and Zumberacko gorje is not adequately organized. Better organization is necessary not only because of the present young generation but also because of the young who will shortly become citizens of the EU, where cycling is enormously popular. Cycling tourism is not known in Zagreb, partly due to inadequate roads. The surroundings of Zagreb are more suitable for cycling tourism and attractive brochures and tourist guides offer information to tourists on bikes. Professional, acrobatic and sports cycling do not have a tradition in Zagreb and in Croatia. The same holds true for recreational cycling and indoor exercise cycling. The authors discuss the impact of popularization of cycling using print and electronic media. The role of district and local self-government in the construction and improvement of traffic roads in Zagreb is very important. It is also significant for the implementation of legal regulations that must be obeyed by all traffic participants in order to protect cyclists, the most vulnerable group of traffic participants besides passengers. Multidisciplinary action of all benevolent experts would surely increase safety and pleasure of cycling in the city and its surroundings. This would also help reduce daily stress and improve the quality of living in the capital of Croatia. PMID:18949922

Matos, Stipan; Krapac, Ladislav; Krapac, Josip

2007-01-01

379

Cycling Through Plants  

NSDL National Science Digital Library

Through a sequence of three related learning cycles--exploring seeds, germinating seeds and monitoring plant experiments--third-grade students answer answer these and other questions about plant growth and discover that new seeds are made from the plants they grow. The activities in these learning cycles are not new, however they are uniquely presented as connected learning experiences with some cycles occuring simultaneously.

Ann Cavallo

2005-04-01

380

Seeing the Carbon Cycle  

NSDL National Science Digital Library

The most important biochemical reactions for life in the ocean and on Earth are cellular respiration and photosynthesis. These two reactions play a central role in the carbon cycle. The ocean-based carbon cycle is highly relevant to today's students because of its key role in global warming. This experiment allows middle school students to observe the influence of the carbon cycle on algae growth, explore experimental design, collect data, and draw a conclusion.

Catherine Cramer

2006-01-01

381

The Water Cycle  

NSDL National Science Digital Library

The representation is a detailed, labeled diagram of the water cycle. Included in the representation are the major concepts of evaporation, precipitation and ground infiltration, as well as more advanced ideas such as evapotranspiration, and water storage. Above and below the diagram are several paragraphs that provide an introduction to the water cycle, a quick summary of the parts of the water cycle and information about global water distribution.

382

The Water Cycle  

NSDL National Science Digital Library

This lesson was developed to give participants an understanding of Earth's water cycle. In this one-hour long activity, students participate in a webquest to learn about the water cycle, and then build a mini-model of the water cycle to observe how water moves through Earth's four systems. The activity uses the 5E instructional model and is part of the "Survivor Earth" series of one-hour lessons.

2014-08-18

383

The Carbon Cycle  

NSDL National Science Digital Library

This Earth Observatory site contains detailed information on the carbon cycle of the Earth. It provides an explanation of the role of carbon in the geologic carbon cycle followed by a discussion of carbon in the life process, including photosynthesis and respiration. Carbon sinks on land and in the ocean are covered next, followed by the human role in the cycle. Lastly, the activity of the National Aeronautics and Space Administration, (NASA), and that of the National Oceanic and Atmospheric Administration, (NOAA) in the exploration of the connection of the carbon cycle to weather and climate is covered.

2011-04-27

384

The Water Cycle  

NSDL National Science Digital Library

In this project you will learn about the different steps of the water cycle and what happens in each step. By the end of the project you will answer the essential question: How is rain made and why does it rain? There are many important steps that take place in the water cycle. Today we are going to learn about each step and the purpose of each step. Read The Water Cycle Information and think of the key steps in the water cycle. In this graphic organizer that I give you put the ...

Ms. Johnson

2009-10-22

385

Nuclear fuel cycle costs  

SciTech Connect

The costs for the back-end of the nuclear fuel cycle, which were developed as part of the Nonproliferation Alternative Systems Assessment Program (NASAP), are presented. Total fuel cycle costs are given for the pressurized water reactor once-through and fuel recycle systems, and for the liquid-metal fast breeder reactor system. These calculations show that fuel cycle costs are a small part of the total power costs. For breeder reactors, fuel cycle costs are about half that of the present once-through system. The total power cost of the breeder reactor system is greater than that of light-water reactor at today's prices for uranium and enrichment.

Burch, W.D.; Haire, M.J.; Rainey, R.H.

1982-02-01

386

Ecotypic variability in the metabolic response of seeds to diurnal hydration-dehydration cycles and its relationship to seed vigor.  

PubMed

Seeds in the seed bank experience diurnal cycles of imbibition followed by complete dehydration. These conditions pose a challenge to the regulation of germination. The effect of recurring hydration-dehydration (Hy-Dh) cycles were tested on seeds from four Arabidopsis thaliana accessions [Col-0, Cvi, C24 and Ler]. Diurnal Hy-Dh cycles had a detrimental effect on the germination rate and on the final percentage of germination in Col-0, Cvi and C24 ecotypes, but not in the Ler ecotype, which showed improved vigor following the treatments. Membrane permeability measured by ion conductivity was generally increased following each Hy-Dh cycle and was correlated with changes in the redox status represented by the GSSG/GSH (oxidized/reduced glutathione) ratio. Among the ecotypes, Col-0 seeds displayed the highest membrane permeability, whilst Ler was characterized by the greatest increase in electrical conductivity following Hy-Dh cycles. Following Dh 2 and Dh 3, the respiratory activity of Ler seeds significantly increased, in contrast to the other ecotypes, indicative of a dramatic shift in metabolism. These differences were associated with accession-specific content and patterns of change of (i) cell wall-related laminaribiose and mannose; (ii) fatty acid composition, specifically of the unsaturated oleic acid and ?-linoleic acid; and (iii) asparagine, ornithine and the related polyamine putrescine. Furthermore, in the Ler ecotype the content of the tricarboxylic acid (TCA) cycle intermediates fumarate, succinate and malate increased in response to dehydration, in contrast to a decrease in the other three ecotypes. These findings provide a link between seed respiration, energy metabolism, fatty acid ?-oxidation, nitrogen mobilization and membrane permeability and the improved germination of Ler seeds following Hy-Dh cycles. PMID:22156384

Bai, Bing; Sikron, Noga; Gendler, Tanya; Kazachkova, Yana; Barak, Simon; Grafi, Gideon; Khozin-Goldberg, Inna; Fait, Aaron

2012-01-01

387

The Cycle of Life  

NSDL National Science Digital Library

The growing of rapid cycling Brassica rapa, Rbr, through a life cycle from seed to seed can provide the basis for learning many aspects of biology that are relevant to the students? understanding of themselves as individual organisms among themany others inhabiting the Earth.

The Wisconsin Fast Plants Program

388

Rock Cycle Roulette.  

ERIC Educational Resources Information Center

Introduces an activity on the rock cycle. Sets 11 stages representing the transitions of an earth material in the rock cycle. Builds six-sided die for each station, and students move to the stations depending on the rolling side of the die. Evaluates students by discussing several questions in the classroom. Provides instructional information for…

Schmidt, Stan M.; Palmer, Courtney

2000-01-01

389

The carbon cycle revisited  

NASA Technical Reports Server (NTRS)

Discussions during the Global Change Institute indicated a need to present, in some detail and as accurately as possible, our present knowledge about the carbon cycle, the uncertainties in this knowledge, and the reasons for these uncertainties. We discuss basic issues of internal consistency within the carbon cycle, and end by summarizing the key unknowns.

Bolin, Bert; Fung, Inez

1992-01-01

390

The Oxygen Cycle.  

ERIC Educational Resources Information Center

Produced for primary grades, this booklet provides study of the oxygen-carbon dioxide cycle in nature. Line drawings, a minimum amount of narrative, and a glossary of terms make up its content. The booklet is designed to be used as reading material, a coloring book, or for dramatic arts with students acting out parts of the cycle. This work was…

Swant, Gary D.

391

Seeing the Carbon Cycle  

ERIC Educational Resources Information Center

In this article, the authors present a classroom experiment that was developed to introduce middle school learners to the carbon cycle. The experiment deals with transfer of CO[subscript 2] between liquid reservoirs and the effect CO[subscript 2] has on algae growth. It allows students to observe the influence of the carbon cycle on algae growth,…

Drouin, Pamela; Welty, David J.; Repeta, Daniel; Engle-Belknap, Cheryl A.; Cramer, Catherine; Frashure, Kim; Chen, Robert

2006-01-01

392

Water Cycle Animation  

NSDL National Science Digital Library

The water cycle is Earth's natural mechanism for transporting and recycling water between the surface and the atmosphere. Through the processes of condensation, precipitation, infiltration, runoff, transpiration, and evaporation, water continuously travels from the atmosphere to the ground and back again. In this animation from NASA, users can observe the steps of the water cycle. The segment is fifty-two seconds in length.

393

mathematical Study program cycle  

E-print Network

127 mathematical statistics Master's study programms #12;128 #12;· Study program cycle: Second cycle study program without subprograms or modules. · Anticipated academic title: Master in Mathematical · Basic goals: The principal goal of the study program in Mathematical Statistics is to create highly

?umer, Slobodan

394

Hair Cycle and Alopecia  

Microsoft Academic Search

Male pattern alopecia is the outcome of profound modifications in the duration, succession and frequency of hair cycles. These phenomena were studied by phototrichogram in 10 male subjects, with or without alopecia, over a period of 15 years. Almost 10,000 hair cycles were accounted for, yielding a detailed picture of the alopecia condition: (1) A decrease in the duration of

Monique Courtois; Geneviève Loussouarn; Colette Hourseau; Jean François Grollier

1994-01-01

395

Heterotrimeric G Protein Cycle  

NSDL National Science Digital Library

This animation shows the basic heterotrimeric G protein cycle and allows the user to then add three different regulators of the cycle, an RGS (regulator of G protein signaling) protein, a GDI (guanine nucleotide dissociation inhibitor) protein, or a guanine nucleotide exchange factor (GEF).

Anita Preininger (Vanderbilt University Medical Center; Department of Pharmacology)

2004-02-03

396

Cycles in dense digraphs  

E-print Network

Let G be a digraph (without parallel edges) such that every directed cycle has length at least four; let ?(G) denote the size of the smallest subset X ? E(G) such that G \\ X has no directed cycles, and let ?(G) be the number of unordered pairs {u, v} of vertices such that u, v are nonadjacent in G

Maria Chudnovsky; Blair Sullivan; Paul Seymour

2007-01-01

397

The Water Cycle  

NSDL National Science Digital Library

Students will work with interactive internet resources to learn all about the water cycle. Fourth Grade Science Standard 1 Objective 2: Describe the water cycle. Locate examples of evaporation and condensation in the water cycle (e.g., water evaporates when heated and clouds or dew forms when vapor is cooled). Describe the processes of evaporation, condensation, and precipitation as they relate to the water cycle. Identify locations that hold water as it passes through the water cycle (e.g., oceans, atmosphere, fresh surface water, snow, ice, and ground water). Construct a model or diagram to show how water continuously moves through the water cycle over time. Describe how the water cycle relates to the water supply in your community. Web Quest Links Introduction Task Resources Evaluation Conclusion Teacher Guide Introduction Have you ever wondered how water gets from oceans, lakes, streams, or clouds into your glass? Check out the following links to learn more about it! TASK Start out by learning the concepts in this song from Bill Nye! Bill Nye the Science Guy- Water Cycle Jump Look ...

Ms. Lish

2009-04-06

398

Human Water Cycle  

NSDL National Science Digital Library

Students learn about the human water cycle, or how humans impact the water cycle by settling down in civilizations. Specifically, they learn how people obtain, use and dispose of water. Students also learn about shortages of treated, clean and safe water and learn about ways that engineers address this issue through water conservation and graywater recycling.

Integrated Teaching and Learning Program,

399

Exploring the Water Cycle  

NSDL National Science Digital Library

In this lesson, students will learn about the water cycle and how energy from the sun and the force of gravity drive this cycle. The emphasis in this lesson will be on having students understand the processes that take place in moving water through Earth’s system.

400

Understanding the Hydrologic Cycle  

NSDL National Science Digital Library

This module helps students gain a basic understanding of the elements of the hydrologic cycle. Making use of illustrations, animations, and interactions, this module examines the basic concepts of the hydrologic cycle including water distribution, atmospheric water, surface water, groundwater, and snowpack/snowmelt.

COMET

2005-11-07

401

Reusable thermal cycling clamp  

NASA Technical Reports Server (NTRS)

A reusable metal clamp for retaining a fused quartz ampoule during temperature cycling in the range of 20 deg C to 1000 deg C is described. A compressible graphite foil having a high radial coefficient of thermal expansion is interposed between the fused quartz ampoule and metal clamp to maintain a snug fit between these components at all temperature levels in the cycle.

Debnam, W. J., Jr.; Fripp, A. L.; Crouch, R. K. (inventors)

1985-01-01

402

Chapman Cycle Equilibrium Calculator  

NSDL National Science Digital Library

The Chapman Cycle Equilibrium Calculator solves for the equilibrium solution of the chemical reactions in the Chapman Cycle, assuming a solar flux equivalent to that at the top of the Earth's atmosphere. A Newton-Rhapson method is used to find the solution, which requires an initial guess as to the equilibrium solution.

The Shodor Education Foundation, Inc.

403

Measuring Cycling Effort.  

ERIC Educational Resources Information Center

Investigates the basic mechanics of cycling with a simple reckoning of how much effort is needed from the cyclist. The work done by the cyclist is quantified when the ride is on the flat and also when pedaling uphill. Proves that by making use of the available gears on a mountain bike, cycling uphill can be accomplished without pain. (Author/ASK)

Jahnke, Thomas; Hamson, Mike

1999-01-01

404

Power Plant Cycling Costs  

SciTech Connect

This report provides a detailed review of the most up to date data available on power plant cycling costs. The primary objective of this report is to increase awareness of power plant cycling cost, the use of these costs in renewable integration studies and to stimulate debate between policymakers, system dispatchers, plant personnel and power utilities.

Kumar, N.; Besuner, P.; Lefton, S.; Agan, D.; Hilleman, D.

2012-07-01

405

The Cell Cycle Animation  

NSDL National Science Digital Library

During development from stem to fully differentiated, cells in the body alternately divide (mitosis) and "appear" to be resting (interphase). This sequence of activities exhibited by cells is called the cell cycle. Watch this animation to learn more about each of the stages in the cell cycle: interphase, gap 0, gap 1, S Phase, gap 2, and M phase.

2010-01-01

406

International Real Business Cycles  

Microsoft Academic Search

The authors ask whether a two-country business cycle model can account simultaneously for domestic and international aspects of business cycles. With this question in mind, the authors document a number of discrepancies between theory and data. The most striking discrepancy concerns the correlations of consumption and output across countries. In this data, outputs are generally more highly correlated across countries

David K. Backus; Patrick J. Kehoe; Finn E. Kydland

1992-01-01

407

Thermoeconomic analysis of an irreversible Stirling heat pump cycle  

NASA Astrophysics Data System (ADS)

In this paper an analysis of the Stirling cycle in thermoeconomic terms is developed using the entropy generation. In the thermoeconomic optimization of an irreversible Stirling heat pump cycle the F function has been introduced to evaluate the optimum for the higher and lower sources temperature ratio in the cycle: this ratio represents the value which optimizes the cycle itself. The variation of the function F is proportional to the variation of the entropy generation, the maxima and minima of F has been evaluated in a previous paper without giving the physical foundation of the method. We investigate the groundwork of this approach: to study the upper and lower limits of F function allows to determine the cycle stability and the optimization conditions. The optimization consists in the best COP at the least cost. The principle of maximum variation for the entropy generation becomes the analytic foundation of the optimization method in the thermoeconomic analysis for an irreversible Stirling heat pump cycle.

Lucia, U.; Gervino, G.

2006-03-01

408

VQ2. Ecosystem Function, Physiology and Seasonal Activity  

E-print Network

VQ2. Ecosystem Function, Physiology and Seasonal Activity What are the seasonal expressions and cycles for terrestrial and aquatic ecosystems, functional groups, and diagnostic species? How and cycles for terrestrial and aquatic ecosystems, functional groups, and diagnostic species? How

Christian, Eric

409

Trophic Interaction Cycles in Tundra Ecosystems and the Impact of Climate Change  

Microsoft Academic Search

While population cycles are geographically widespread, it is on arctic tundra that such cycles appear to be most influential for the functioning of the whole ecosystem. We give an overview of tundra species that exhibit population cycles and describe what are currently believed to be the causal mechanisms. Population cycles most likely originate from trophic interactions within the plant-based tundra