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1

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

2

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

E-print Network

in the germline of patients with hereditary leiomyomatosis and renal cell cancer (HLRCC). This mutation results in a non-functional TCA cycle, but kidney cells with this mutation can form aggressive tumoursFumarate hydratase (FH), an enzyme in the tricarboxylic acid (TCA) cycle, is mutated

Ruppin, Eytan

3

ABNORMALITIES IN THE TRICARBOXYLIC ACID (TCA) CYCLE IN BRAIN OF SCHIZOPHRENIA PATIENTS  

PubMed Central

Images of brain metabolism and measurements of activities of components of the electron transport chain support earlier studies that suggest that brain glucose oxidation is inherently abnormal in a significant proportion of persons with schizophrenia. Therefore, we measured activities of enzymes of the tricarboxylic (TCA) cycle in dorsolateral-prefrontal-cortex from schizophrenia patients (N=13) and non-psychiatric disease controls (N=13): the pyruvate dehydrogenase complex (PDHC), citrate synthase (CS), aconitase, isocitrate dehydrogenase (ICDH), the alpha-ketoglutarate dehydrogenase complex (KGDHC), succinate thiokinase (STH), succinate dehydrogenase (SDH), fumarase and malate dehydrogenase (MDH). Activities of aconitase (18.4%, p<0.05), KGDHC (26%) and STH (28.2%, p<0.05), enzymes in the first half of the TCA cycle, were lower, but SDH (18.3%, p<0.05) and MDH (34%, p<0.005), enzymes in the second half, were higher than controls. PDHC, CS, ICDH and fumarase activities were unchanged. There were no significant correlations between enzymes of TCA cycle and cognitive function, age or choline acetyl transferase activity, except for aconitase activity which decreased slightly with age (r=0.55, p=003). The increased activities of dehydrogenases in the second half of the TCA cycle may reflect a compensatory response to reduced activities of enzymes in the first half. Such alterations in the components of TCA cycle are adequate to alter the rate of brain metabolism. These results are consistent with the imaging studies of hypometabolism in schizophrenia. They suggest that deficiencies in mitochondrial enzymes can be associated with mental disease that takes the form of schizophrenia. PMID:21123035

Bubber, P; Hartounian, V; Gibson, GE; Blass, JP

2010-01-01

4

Part II. The Tricarboxylic Acid (TCA), Citric Acid, or Krebs Cycle George M. Bodner  

E-print Network

Metabolism Part II. The Tricarboxylic Acid (TCA), Citric Acid, or Krebs Cycle George M. Bodner this sequence of en- zyme-catalyzed reactions the tricarboxylic acid cycle. The tricarboxylic acid (TCA), citric acid, or Krehs cycle differs fromglycolysisin several ways. First, and foremost, it is a cyclic rather

Bodner, George M.

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

11/12/13 Chapter 13 -TCA Cycle  

E-print Network

;11/12/13 5 In eukaryotes, the Citric Acid Cycle / Krebs Cycle / Tricarboxylic Acid Cycle acetate Pantothenic Acid -mercapto-ethylamine -- - - ! #12;11/12/13 3 Lipoic Acid S S CH CH2 CH2 CH2 CH2 CH2 CH2 C O HN CH2 CH2 CH2 CH2 CH N C O H Lys of E2 E2 Lipoic Acid ! The reaction starts on E1 and ends on E

O'Neil, Joe

7

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

PubMed

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-(13)C]-glucose as the tracer, both glucose consumption and lactate production were increased by MYC expression and hypoxia. Using [U-(13)C,(15)N]-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 (13)C-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

8

Effects of intermediate metabolite carboxylic acids of TCA cycle on Microcystis with overproduction of phycocyanin.  

PubMed

Toxic Microcystis species are the main bloom-forming cyanobacteria in freshwaters. It is imperative to develop efficient techniques to control these notorious harmful algal blooms (HABs). Here, we present a simple, efficient, and environmentally safe algicidal way to control Microcystis blooms, by using intermediate carboxylic acids from the tricarboxylic acid (TCA) cycle. The citric acid, alpha-ketoglutaric acid, succinic acid, fumaric acid, and malic acid all exhibited strong algicidal effects, and particularly succinic acid could cause the rapid lysis of Microcystis in a few hours. It is revealed that the Microcystis-lysing activity of succinic acid and other carboxylic acids was due to their strong acidic activity. Interestingly, the acid-lysed Microcystis cells released large amounts of phycocyanin, about 27-fold higher than those of the control. On the other hand, the transcription of mcyA and mcyD of the microcystin biosynthesis operon was not upregulated by addition of alpha-ketoglutaric acid and other carboxylic acids. Consider the environmental safety of intermediate carboxylic acids. We propose that administration of TCA cycle organic acids may not only provide an algicidal method with high efficiency and environmental safety but also serve as an applicable way to produce and extract phycocyanin from cyanobacterial biomass. PMID:25342454

Bai, Shijie; Dai, Jingcheng; Xia, Ming; Ruan, Jing; Wei, Hehong; Yu, Dianzhen; Li, Ronghui; Jing, Hongmei; Tian, Chunyuan; Song, Lirong; Qiu, Dongru

2014-10-24

9

A Possibility for Piece-wise Ignitions of a TCA Cycle in a Prebiotic Hydrothermal Environment  

NASA Astrophysics Data System (ADS)

We previously reported that formic and acetic acids were synthesized from the mixture of carbon dioxide and water in the presence of heated metal oxide serving as a catalyst (1). Fixation of carbon dioxide and monoxide could have been conceivable in the hydrothermal environment in the primitive ocean. We then considered a possibility of synthesizing major metabolites appearing in a TCA cycle in prebiotic conditions. Focused in this attempt was the vicinity of hydrothermal vents in the primitive ocean. We used a flow reactor to simulate hydrothermal circulation of seawater through hot vents (2). The experimental conditions we chose were that the hot chamber at 200 °C was connected to the cold chamber at 0 °C through a thin nozzle of its diameter 0.8 mm. The total volume of the reaction solution was 500 mL. The fluid was circulated through the flow reactor at the rate of 8 mL / min. As an initial attempt, we prepared the solution of acetic and formic acids. When iron chloride and copper sulfide were present in the solution, the products precipitated on the filter placed in the low-temperature chamber included di-carboxylic acids such as malic acid. We then proceeded to the reaction solution dissolving three different kinds of carboxylic acids, namely, succinate, fumarate, and oxoglutarate. We found that malic acid was in the solution after the operation of the flow-reactor. Formation and transformation of carboxylic acids were observed in our flow reactor. These observations, when combined together, may suggest a possibility of piece-wise ignitions of a TCA cycle even in the prebiotic ocean on the primitive earth. References (1) R. Terada, E. Imai, H. Honda, K. Hatori, and K. Matsuno.: Viva Origino 27, 197-208(1999). (2) E. Imai, H. Honda, K. Hatori, A. Brack, and K. Matsuno.: Science 283, 831-833(1999).

Nemoto, A.; Ikeya, R.; Imai, E.; Hatori, K.; Honda, H.; Matsuno, K.

10

Blocking anaplerotic entry of glutamine into the TCA cycle sensitizes K-Ras mutant cancer cells to cytotoxic drugs.  

PubMed

Cancer cells undergo a metabolic transformation that allows for increased anabolic demands, wherein glycolytic and tricarboxylic acid (TCA) cycle intermediates are shunted away for the synthesis of biological molecules required for cell growth and division. One of the key shunts is the exit of citrate from the mitochondria and the TCA cycle for the generation of cytosolic acetyl-coenzyme A that can be used for fatty acid and cholesterol biosynthesis. With the loss of mitochondrial citrate, cancer cells rely on the 'conditionally essential' amino acid glutamine (Q) as an anaplerotic carbon source for TCA cycle intermediates. Although Q deprivation causes G1 cell cycle arrest in non-transformed cells, its impact on the cancer cell cycle is not well characterized. We report here a correlation between bypass of the Q-dependent G1 checkpoint and cancer cells harboring K-Ras mutations. Instead of arresting in G1 in response to Q-deprivation, K-Ras-driven cancer cells arrest in either S- or G2/M-phase. Inhibition of K-Ras effector pathways was able to revert cells to G1 arrest upon Q deprivation. Blocking anaplerotic utilization of Q mimicked Q deprivation-causing S- and G2/M-phase arrest in K-Ras mutant cancer cells. Significantly, Q deprivation or suppression of anaplerotic Q utilization created synthetic lethality to the cell cycle phase-specific cytotoxic drugs, capecitabine and paclitaxel. These data suggest that disabling of the G1 Q checkpoint could represent a novel vulnerability of cancer cells harboring K-Ras and possibly other mutations that disable the Q-dependent checkpoint.Oncogene advance online publication, 14 July 2014; doi:10.1038/onc.2014.207. PMID:25023699

Saqcena, M; Mukhopadhyay, S; Hosny, C; Alhamed, A; Chatterjee, A; Foster, D A

2014-07-14

11

TCA precipitation.  

PubMed

Trichloroacetic acid (TCA) precipitation of proteins is commonly used to concentrate protein samples or remove contaminants, including salts and detergents, prior to downstream applications such as SDS-PAGE or 2D-gels. TCA precipitation denatures the protein, so it should not be used if the protein must remain in its folded state (e.g., if you want to measure a biochemical activity of the protein). PMID:24674058

Koontz, Laura

2014-01-01

12

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

13

Exposure of Clinical MRSA Heterogeneous Strains to ?-Lactams Redirects Metabolism to Optimize Energy Production through the TCA Cycle  

PubMed Central

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as one of the most important pathogens both in health care and community-onset infections. The prerequisite for methicillin resistance is mecA, which encodes a ?-lactam-insensitive penicillin binding protein PBP2a. A characteristic of MRSA strains from hospital and community associated infections is their heterogeneous expression of resistance to ?-lactam (HeR) in which only a small portion (?0.1%) of the population expresses resistance to oxacillin (OXA) ?10 µg/ml, while in other isolates, most of the population expresses resistance to a high level (homotypic resistance, HoR). The mechanism associated with heterogeneous expression requires both increase expression of mecA and a mutational event that involved the triggering of a ?-lactam-mediated SOS response and related lexA and recA genes. In the present study we investigated the cellular physiology of HeR-MRSA strains during the process of ?-lactam-mediated HeR/HoR selection at sub-inhibitory concentrations by using a combinatorial approach of microarray analyses and global biochemical profiling employing gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) to investigate changes in metabolic pathways and the metabolome associated with ?-lactam-mediated HeR/HoR selection in clinically relevant heterogeneous MRSA. We found unique features present in the oxacillin-selected SA13011-HoR derivative when compared to the corresponding SA13011-HeR parental strain that included significant increases in tricarboxyl citric acid (TCA) cycle intermediates and a concomitant decrease in fermentative pathways. Inactivation of the TCA cycle enzyme cis-aconitase gene in the SA13011-HeR strain abolished ?-lactam-mediated HeR/HoR selection demonstrating the significance of altered TCA cycle activity during the HeR/HoR selection. These results provide evidence of both the metabolic cost and the adaptation that HeR-MRSA clinical strains undergo when exposed to ?-lactam pressure, indicating that the energy production is redirected to supply the cell wall synthesis/metabolism, which in turn contributes to the survival response in the presence of ?-lactam antibiotics. PMID:23940684

Keaton, Mignon A.; Rosato, Roberto R.; Plata, Konrad B.; Singh, Christopher R.; Rosato, Adriana E.

2013-01-01

14

GC/TOFMS analysis of metabolites in serum and urine reveals metabolic perturbation of TCA cycle in db/db mice involved in diabetic nephropathy.  

PubMed

Early diagnosis of diabetic nephropathy (DN) is difficult although it is of crucial importance to prevent its development. To probe potential markers and the underlying mechanism of DN, an animal model of DN, the db/db mice, was used and serum and urine metabolites were profiled using gas chromatography/time-of-flight mass spectrometry. Metabolic patterns were evaluated based on serum and urine data. Principal component analysis of the data revealed an obvious metabonomic difference between db/db mice and controls, and db/db mice showed distinctly different metabolic patterns during the progression from diabetes to early, medium, and later DN. The identified metabolites discriminating between db/db mice and controls suggested that db/db mice have perturbations in the tricarboxylic acid cycle (TCA, citrate, malate, succinate, and aconitate), lipid metabolism, glycolysis, and amino acid turnover. The db/db mice were characterized by acidic urine, high TCA intermediates in serum at week 6 and a sharp decline thereafter, and gradual elevation of free fatty acids in the serum. The sharp drop of serum TCA intermediates from week 6 to 8 indicated the downregulated glycolysis and insulin resistance. However, urinary TCA intermediates did not decrease in parallel with those in the serum from week 6 to 10, and an increased portion of TCA intermediates in the serum was excreted into the urine at 8, 10, and 12 wk than at 6 wk, indicating kidney dysfunction occurred. The relative abundances of TCA intermediates in urine relative to those in serum were suggested as an index of renal damage. PMID:23467425

Li, Mengjie; Wang, Xufang; Aa, Jiye; Qin, Weisong; Zha, Weibin; Ge, Yongchun; Liu, Linsheng; Zheng, Tian; Cao, Bei; Shi, Jian; Zhao, Chunyan; Wang, Xinwen; Yu, Xiaoyi; Wang, Guangji; Liu, Zhihong

2013-06-01

15

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

16

The Aspergillus nidulans acuL gene encodes a mitochondrial carrier required for the utilization of carbon sources that are metabolized via the TCA cycle.  

PubMed

In Aspergillus nidulans, the utilization of acetate as sole carbon source requires several genes (acu). Most of them are also required for the utilization of fatty acids. This is the case for acuD and acuE, which encode the two glyoxylate cycle-specific enzymes, isocitrate lyase and malate synthase, respectively, but also for acuL that we have identified as AN7287, and characterized in this study. Deletion of acuL resulted in the same phenotype as the original acuL217 mutant. acuL encodes a 322-amino acid protein which displays all the structural features of a mitochondrial membrane carrier, and shares 60% identity with the Saccharomyces cerevisiae succinate/fumarate mitochondrial antiporter Sfc1p (also named Acr1p). Consistently, the AcuL protein was shown to localize in mitochondria, and partial cross-complementation was observed between the S. cerevisiae and A. nidulans homologues. Extensive phenotypic characterization suggested that the acuL gene is involved in the utilization of carbon sources that are catabolized via the TCA cycle, and therefore require gluconeogenesis. In addition, acuL proves to be co-regulated with acuD and acuE. Overall, our data suggest that AcuL could link the glyoxylate cycle to gluconeogenesis by exchanging cytoplasmic succinate for mitochondrial fumarate. PMID:24835019

Flipphi, Michel; Oestreicher, Nathalie; Nicolas, Valérie; Guitton, Audrey; Vélot, Christian

2014-07-01

17

Ames Optimized TCA Configuration  

NASA Technical Reports Server (NTRS)

Configuration design at Ames was carried out with the SYN87-SB (single block) Euler code using a 193 x 49 x 65 C-H grid. The Euler solver is coupled to the constrained (NPSOL) and the unconstrained (QNMDIF) optimization packages. Since the single block grid is able to model only wing-body configurations, the nacelle/diverter effects were included in the optimization process by SYN87's option to superimpose the nacelle/diverter interference pressures on the wing. These interference pressures were calculated using the AIRPLANE code. AIRPLANE is an Euler solver that uses a unstructured tetrahedral mesh and is capable of computations about arbitrary complete configurations. In addition, the buoyancy effects of the nacelle/diverters were also included in the design process by imposing the pressure field obtained during the design process onto the triangulated surfaces of the nacelle/diverter mesh generated by AIRPLANE. The interference pressures and nacelle buoyancy effects are added to the final forces after each flow field calculation. Full details of the (recently enhanced) ghost nacelle capability are given in a related talk. The pseudo nacelle corrections were greatly improved during this design cycle. During the Ref H and Cycle 1 design activities, the nacelles were only translated and pitched. In the cycle 2 design effort the nacelles can translate vertically, and pitch to accommodate the changes in the lower surface geometry. The diverter heights (between their leading and trailing edges) were modified during design as the shape of the lower wing changed, with the drag of the diverter changing accordingly. Both adjoint and finite difference gradients were used during optimization. The adjoint-based gradients were found to give good direction in the design space for configurations near the starting point, but as the design approached a minimum, the finite difference gradients were found to be more accurate. Use of finite difference gradients was limited by the CPU time limit available on the Cray machines. A typical optimization run using finite difference gradients can use only 30 to 40 design variables and one optimization iteration within the 8 hour queue limit for the chosen grid size and convergence level. The efficiency afforded by the adjoint method allowed for 50-120 design variables and 5-10 optimization iterations in the 8 hour queue. Geometric perturbations to the wing and fuselage were made using the Hicks/Henne (HH) shape functions. The HH functions were distributed uniformly along the chords of the wing defining sections and lofted linearly. During single-surface design, constraints on thickness and volume at selected wing stations were imposed. Both fuselage camber and cross-sectional area distributions were permitted to change during design. The major disadvantage to the use of these functions is the inherent surface waviness produced by repeated use of such functions. Many smoothing operations were required following optimization runs to produce a configuration with reasonable smoothness. Wagner functions were also used on the wing sections but were never used on the fuselage. The Wagner functions are a family of increasingly oscillatory functions that have also been used extensively in airfoil design. The leading and trailing edge regions of the wing were designed by use of polynomial and monomial functions respectively. Twist was attempted but was abandoned because of little performance improvement available from changing the baseline twist.

Cliff, Susan E.; Reuther, James J.; Hicks, Raymond M.

1999-01-01

18

Global Transcription Analysis of Krebs Tricarboxylic Acid Cycle Mutants Reveals an Alternating Pattern of Gene Expression and Effects on Hypoxic and Oxidative GenesD?  

PubMed Central

To understand the many roles of the Krebs tricarboxylic acid (TCA) cycle in cell function, we used DNA microarrays to examine gene expression in response to TCA cycle dysfunction. mRNA was analyzed from yeast strains harboring defects in each of 15 genes that encode subunits of the eight TCA cycle enzymes. The expression of >400 genes changed at least threefold in response to TCA cycle dysfunction. Many genes displayed a common response to TCA cycle dysfunction indicative of a shift away from oxidative metabolism. Another set of genes displayed a pairwise, alternating pattern of expression in response to contiguous TCA cycle enzyme defects: expression was elevated in aconitase and isocitrate dehydrogenase mutants, diminished in ?-ketoglutarate dehydrogenase and succinyl-CoA ligase mutants, elevated again in succinate dehydrogenase and fumarase mutants, and diminished again in malate dehydrogenase and citrate synthase mutants. This pattern correlated with previously defined TCA cycle growth–enhancing mutations and suggested a novel metabolic signaling pathway monitoring TCA cycle function. Expression of hypoxic/anaerobic genes was elevated in ?-ketoglutarate dehydrogenase mutants, whereas expression of oxidative genes was diminished, consistent with a heme signaling defect caused by inadequate levels of the heme precursor, succinyl-CoA. These studies have revealed extensive responses to changes in TCA cycle function and have uncovered new and unexpected metabolic networks that are wired into the TCA cycle. PMID:12631716

McCammon, Mark T.; Epstein, Charles B.; Przybyla-Zawislak, Beata; McAlister-Henn, Lee; Butow, Ronald A.

2003-01-01

19

Viscous Design of TCA Configuration  

NASA Technical Reports Server (NTRS)

The goal in this effort is to redesign the baseline TCA configuration for improved performance at both supersonic and transonic cruise. Viscous analyses are conducted with OVERFLOW, a Navier-Stokes code for overset grids, using PEGSUS to compute the interpolations between overset grids. Viscous designs are conducted with OVERDISC, a script which couples OVERFLOW with the Constrained Direct Iterative Surface Curvature (CDISC) inverse design method. The successful execution of any computational fluid dynamics (CFD) based aerodynamic design method for complex configurations requires an efficient method for regenerating the computational grids to account for modifications to the configuration shape. The first section of this presentation deals with the automated regridding procedure used to generate overset grids for the fuselage/wing/diverter/nacelle configurations analysed in this effort. The second section outlines the procedures utilized to conduct OVERDISC inverse designs. The third section briefly covers the work conducted by Dick Campbell, in which a dual-point design at Mach 2.4 and 0.9 was attempted using OVERDISC; the initial configuration from which this design effort was started is an early version of the optimized shape for the TCA configuration developed by the Boeing Commercial Airplane Group (BCAG), which eventually evolved into the NCV design. The final section presents results from application of the Natural Flow Wing design philosophy to the TCA configuration.

Krist, Steven E.; Bauer, Steven X. S.; Campbell, Richard L.

1999-01-01

20

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

21

Evolution and functional implications of the tricarboxylic acid cycle as revealed by phylogenetic analysis.  

PubMed

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

2014-10-01

22

Inactivation of a novel three-cistronic operon tcaR-tcaA-tcaB increases teicoplanin resistance in Staphylococcus aureus  

Microsoft Academic Search

A novel teicoplanin-associated operon termed tcaR-tcaA-tcaB was identified by Tn917-mediated insertional mutagenesis. Resistance to teicoplanin rose 4-fold by insertional inactivation of tcaA or by deletion of the entire operon. tcaA encodes a hypothetical transmembrane protein with a metal-binding motif, possibly a sensor–transducer. tcaB codes for a membrane-associated protein, which has sequence homologies to a bicyclomycin resistance protein. The two genes

Marcel Brandenberger; Martin Tschierske; Philipp Giachino; Akihito Wada; Brigitte Berger-Bächi

2000-01-01

23

Inactivation of a novel three-cistronic operon tcaR-tcaA-tcaB increases teicoplanin resistance in Staphylococcus aureus.  

PubMed

A novel teicoplanin-associated operon termed tcaR-tcaA-tcaB was identified by Tn917-mediated insertional mutagenesis. Resistance to teicoplanin rose 4-fold by insertional inactivation of tcaA or by deletion of the entire operon. tcaA encodes a hypothetical transmembrane protein with a metal-binding motif, possibly a sensor-transducer. tcaB codes for a membrane-associated protein, which has sequence homologies to a bicyclomycin resistance protein. The two genes are preceded by tcaR encoding a putative regulator with sequence homologies to the transcriptional regulator MarR. The fact that tcaA inactivation as well as deletion of tcaRAB produced the same increase in teicoplanin resistance confirmed the association of tcaRAB with teicoplanin susceptibility. Cotransductional crosses showed that the level of teicoplanin resistance produced by these insertions was strain-dependent and that in the methicillin-resistant strain COL, it was paired with a remarkable decrease in methicillin resistance. This allowed to postulate that tcaRAB may be involved in some way in cell wall biosynthesis, and that teicoplanin may interact with TcaA and/or TcaB either directly or indirectly. PMID:11042376

Brandenberger, M; Tschierske, M; Giachino, P; Wada, A; Berger-Bächi, B

2000-10-18

24

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

25

ATCA/muTCA for Physics  

SciTech Connect

ATCA/{mu}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 and D efforts where ATCA and {mu}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/{mu}TCA specifications to promote inter-operability of laboratory and industry designs for physics.

Jezynski, Tomasz; /DESY; Larsen, Raymond; /SLAC; Le Du, Patrick; /Lyon, IPN

2012-06-14

26

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

27

Unstructured Navier-Stokes Analysis of Full TCA Configuration  

NASA Technical Reports Server (NTRS)

This paper presents an Unstructured Navier-Stokes Analysis of Full TCA (Technology Concept Airplane) Configuration. The topics include: 1) Motivation; 2) Milestone and approach; 3) Overview of the unstructured-grid system; 4) Results on full TCA W/B/N/D/E configuration; 5) Concluding remarks; and 6) Future directions.

Frink, Neal T.; Pirzadeh, Shahyar Z.

1999-01-01

28

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

29

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

30

Influence of Carbohydrate on Immune Function Following 2 h Cycling  

Microsoft Academic Search

The influence of carbohydrate compared with placebo ingestion on changes in immune cell counts and functions following 2 h intensive cycling was studied in 12 trained cyclists who functioned as their own controls. The subjects performed two tests 2 weeks apart where they cycled for 2 h at ?64% Wattsmax while receiving 4 mL·kg·15 min carbohydrate (6%) (Cho) or placebo

David C. Nieman; Dru A. Henson; Greg Gojanovich; J. Mark Davis; E. Angela Murphy; Eugene P. Mayer; Steven Pearce; Charles L. Dumke; Alan C. Utter; Steven R. McAnulty; Lisa S. McAnulty

2006-01-01

31

Physical interactions between tricarboxylic acid cycle enzymes in Bacillus subtilis: evidence for a metabolon.  

PubMed

The majority of all proteins of a living cell is active in complexes rather than in an isolated way. These protein-protein interactions are of high relevance for many biological functions. In addition to many well established protein complexes an increasing number of protein-protein interactions, which form rather transient complexes has recently been discovered. The formation of such complexes seems to be a common feature especially for metabolic pathways. In the Gram-positive model organism Bacillus subtilis, we identified a protein complex of three citric acid cycle enzymes. This complex consists of the citrate synthase, the isocitrate dehydrogenase, and the malate dehydrogenase. Moreover, fumarase and aconitase interact with malate dehydrogenase and with each other. These five enzymes catalyze sequential reaction of the TCA cycle. Thus, this interaction might be important for a direct transfer of intermediates of the TCA cycle and thus for elevated metabolic fluxes via substrate channeling. In addition, we discovered a link between the TCA cycle and gluconeogenesis through a flexible interaction of two proteins: the association between the malate dehydrogenase and phosphoenolpyruvate carboxykinase is directly controlled by the metabolic flux. The phosphoenolpyruvate carboxykinase links the TCA cycle with gluconeogenesis and is essential for B. subtilis growing on gluconeogenic carbon sources. Only under gluconeogenic growth conditions an interaction of these two proteins is detectable and disappears under glycolytic growth conditions. PMID:20933603

Meyer, Frederik M; Gerwig, Jan; Hammer, Elke; Herzberg, Christina; Commichau, Fabian M; Völker, Uwe; Stülke, Jörg

2011-01-01

32

Citric acid cycle and role of its intermediates in metabolism.  

PubMed

The citric acid cycle is the final common oxidative pathway for carbohydrates, fats and amino acids. It is the most important metabolic pathway for the energy supply to the body. TCA is the most important central pathway connecting almost all the individual metabolic pathways. In this review article, introduction, regulation and energetics of TCA cycle have been discussed. The present study was carried out to review literature on TCA cycle. PMID:24068518

Akram, Muhammad

2014-04-01

33

Monte Carlo simulations of neutron well-logging in granite and sand to detect water and trichloroethane (TCA)  

SciTech Connect

The Monte Carlo code MCNP is used in simulations of neutron well logging in granite to detect water and TCA (C{sub 2}H{sub 3}Cl{sub 3}), a common ground contaminant, in fractures of 1 cm and 1 mm thickness at various distances and orientations. Also simulated is neutron well logging in wet sand to detect TCA and lead (Pb) at various uniform concentrations. The {sup 3}H(d,n) (DT) and{sup 2}H(d,n) (DD) neutron producing reactions are used in the simulations to assess the relative performance of each. Simulations are also performed to determine the efficiency of several detector materials such as CdZnTe, Ge and NaI as a function of photon energy. Results indicate that, by examining the signal from the 6.11 MeV gamma from the thermal neutron capture of Cl in TCA, trace amounts (few ppm) are detectable in saline free media. Water and TCA filled fractures are also detectable. These results are summarized in Tables 7--21. Motivation for this work is based on the need for detection of trace environmental pollutants as well as possible fracture characterization of geologic media.

Hua, D.D. [Lawrence Berkeley National Lab., CA (United States)]|[Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Donahue, R.J.; Celata, C.M. [Lawrence Berkeley National Lab., CA (United States); Greenspan, E. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering

1998-01-01

34

Biologic activities of the beta-chemokine TCA3 on neutrophils and macrophages.  

PubMed

Previous in vivo and in vitro studies demonstrated that the murine beta-chemokine TCA3 is a chemoattractant for monocytes/macrophages and neutrophils. The ability of TCA3 to activate these cell populations is now evaluated. Treatment with 10 to 20 nM rTCA3 induced a respiratory burst with the production of superoxide and hydrogen peroxide in both casein-elicited and unstimulated neutrophil and macrophage populations. In addition, TCA3 treatment induced the production of reactive nitrogen intermediates, whereas stimulation with higher concentrations (100 nM) of TCA3 induced the exocytosis of lysozyme and elastase in the presence of cytochalasin B (7 micrograms/ml). Subnanomolar concentrations (100 pM) of TCA3 also caused integrin-mediated increases of adhesiveness to fibrinogen by neutrophils and macrophages. Increased adhesiveness is the most sensitive assay for TCA3 bioactivity. TCA3 treatment appears to involve signaling through a G-protein-linked receptor as Pertussis toxin abolished the TCA3-mediated increase of adhesiveness and the production of reactive nitrogen intermediates. The dose dependence of the TCA3-mediated activities indicate a coordinated inflammatory response mediated by varying concentrations of TCA3. PMID:7730638

Devi, S; Laning, J; Luo, Y; Dorf, M E

1995-05-15

35

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

36

Biological catalysis of the hydrological cycle: life's thermodynamic function  

NASA Astrophysics Data System (ADS)

Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living component of the biosphere on the surface of the Earth of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere and its coupling to the water cycle (as well as other abiotic processes), is by far the greatest entropy producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function; acting as a dynamic catalyst by aiding irreversible abiotic process such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow and to spread into initially inhospitable areas.

Michaelian, K.

2011-01-01

37

MicroTCA implementation of synchronous Ethernet-Based DAQ systems for large scale experiments  

E-print Network

MicroTCA implementation of synchronous Ethernet- Based DAQ systems for large scale experiments C data through the µTCA backplane using a Gigabit Ethernet link. The gigabit switch of the MCH is used systems associated with fast trigger processing in order to reduce the amount of data transferred to event

Paris-Sud XI, Université de

38

Structural study of TcaR and its complexes with multiple antibiotics from Staphylococcus epidermidis  

PubMed Central

TcaR and IcaR are a weak and a strong negative regulator of transcription of the ica locus, respectively, and their presence prevents the poly-N-acetylglucosamine production and biofilm formation in Staphylococcus epidermidis. Although TcaR was shown to interact with the ica promoter, the precise binding region and the mechanism of interaction remained unclear. Here we present the 3D structure of TcaR in its apo form and in complex with salicylate as well as several aminoglycoside and ?-lactam antibiotics. A comparison of the native and complex TcaR structures indicates that the mechanism of regulation involves a large conformational change in the DNA-binding lobe. Here, we deduced the consensus binding sequence of two [?TTNNAA] hexamers embedded in a 16 bp sequence for a TcaR dimer. Six TcaR dimers bind specifically to three approximately 33 bp segments close to the IcaR binding region with varying affinities, and their repressor activity is directly interfered by salicylate and different classes of natural antimicrobial compounds. We also found in this study that the antimicrobial compounds we tested were shown not only to inhibit TcaR–DNA interaction but also to further induce biofilm formation in S. epidermidis in our in vivo assay. The results support a general mechanism for antibiotics in regulating TcaR–DNA interaction and thereby help understand the effect of antibiotic exposure on bacterial antibiotic resistance through biofilm formation. PMID:20421503

Chang, Yu-Ming; Jeng, Wen-Yih; Ko, Tzu-Ping; Yeh, Yao-Jen; Chen, Cammy K.-M.; Wang, Andrew H.-J.

2010-01-01

39

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

40

Plasma amino acids imbalance in cirrhotic patients disturbs the tricarboxylic acid cycle of dendritic cell  

PubMed Central

An imbalance of plasma amino acids (AA) is observed cirrhotic patients. Here we report that the imbalance suppresses the maturation of dendritic cells (DCs) by reducing the intracellular ATP due to interference with the mitochondrial tricarboxylic acid (TCA) cycle. We used serum-free culture medium consistent with the average concentration of the plasma AA from a healthy volunteer (HCM) and that from patients with advanced cirrhosis (ACM). We compared the function of DCs and the metabolism of glucose-amino acids under each medium. The maturation and intracellular ATP of immature DCs were lower under ACM in spite of the enhancement of mitochondrial respiratory chain complex genes. Metabolomics revealed that the TCA cycle metabolite, fumarate and 2-oxoglutarate were increased in DCs generated under ACM. Consistent with in vitro, In CD1c+ or CD14+ cells from cirrhotic patients, the gene expression of 2-oxoglutarate-succinate-fumarate transition enzymes were significantly different from the cells of healthy controls. PMID:24322372

Kakazu, Eiji; Kondo, Yasuteru; Kogure, Takayuki; Ninomiya, Masashi; Kimura, Osamu; Ueno, Yoshiyuki; Shimosegawa, Tooru

2013-01-01

41

RANKIN-SELBERG L-FUNCTIONS AND CYCLES ON UNITARY SHIMURA VARIETIES  

E-print Network

RANKIN-SELBERG L-FUNCTIONS AND CYCLES ON UNITARY SHIMURA VARIETIES BENJAMIN HOWARD Contents 1 27 4.1. Gross's calculation 28 4.2. Decomposition of the intersection 28 4.3. Degrees of zero cycles #12;RANKIN-SELBERG L-FUNCTIONS AND CYCLES ON UNITARY SHIMURA VARIETIES 3 defined by x (iC()x, i

Goren, Eyal Z.

42

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...

43

Development of a cellular biosensor for the detection of 2,4,6-trichloroanisole (TCA).  

PubMed

2,4,6-trichloroanisole (TCA) is a microbial metabolite formed from chlorophenols through the activity of several natural fungal strains present on the cork oak bark. TCA is the primary compound responsible for the mousty/mould off-odour known as "cork taint" present in cork stoppers, wine, water and alcoholic beverages. Chromatographic and electrochemical methods are currently used for the determination of TCA, however its detection at low concentrations remains a technical challenge. The aim of this study was the development of a rapid novel biosensor system based on the Bioelectric Recognition Assay (BERA). The sensor measured the electric response of cultured membrane-engineered fibroblast cells suspended in an alginate gel matrix due to the change of their membrane potential in the presence of the analyte. Membrane-engineered cells were prepared by osmotic insertion of 0.5 ?g/l of specific TCA antibodies into the membrane of the cells. The BERA-based sensor was able to detect TCA in a few minutes (3-5 min) at extremely low concentrations (10(-1)ppt), thus demonstrating higher sensitivity than the human sensory threshold. In addition, the assay was quite selective against other haloanisoles and halophenols structurally related to or co-occurring with TCA. Finally the sensor was tested against real white wine samples from cork soaks. At this real test, the BERA sensor was able to detect TCA from cork soaks rapidly (3-5 min) at very low concentrations (1.02-12 ng/l), covering the whole range for the detection threshold for wines (1.4-10 ng/l). Therefore, this novel biosensor offers new perspectives for ultra-rapid, ultra-sensitive and low-cost monitoring of TCA presence in cork and wine and possibly also other food commodities. PMID:21482306

Varelas, Vassileios; Sanvicens, Nuria; M-Pilar-Marco; Kintzios, Spiridon

2011-05-15

44

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

45

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

46

RANKIN-SELBERG L-FUNCTIONS AND CYCLES ON UNITARY SHIMURA VARIETIES  

E-print Network

RANKIN-SELBERG L-FUNCTIONS AND CYCLES ON UNITARY SHIMURA VARIETIES BENJAMIN HOWARD Contents 1 27 4.1. Gross's calculation 27 4.2. Decomposition of the intersection 27 4.3. Degrees of zero cycles. Introduction 1 1.1. Acknowledgements 2 2. Unitary Shimura varieties and their special cycles 2 2.1. Unitary

Howard, Ben

47

A sub-set of ATA over Ethernet as the control protocol in xTCA  

E-print Network

Both ATLAS and CMS are considering xTCA as replacement for VME based systems in their upgrades. An ethernet based protocol is an agnostic choice for module control in both ATCA and uTCA. A sub-set of the simple storage area network protocol ATA over ethernet could satisfy the requirements for module configuration and control without incurring the overheads of running IP on an FPGA. Members of the RAL ATLAS and CMS trigger groups are investigating implementing this sub-set in the first instance using a Xilinx development board and replacing the UDP/IP layer in the existing CMS IPBus protocol.

Sankey, DPC; The ATLAS collaboration

2011-01-01

48

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

49

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

50

Functional models of electrochromic devices: cycling capacity and degradation  

Microsoft Academic Search

Electrical transfer and diffusion of ions and the irreversibility of ion and electron processes in heterojunctions are responsible for degradation of ionic devices. These processes for electrochromic devices (ECD) determine the cycling capacity and lifetime. The basic problem here is how to match the electrochemical parameters (including chemical potential) of heterojunction. The experiments had been carried out on ECD based

Andrejs R. Lusis

1997-01-01

51

Multiple Targets of Nitric Oxide in the Tricarboxylic Acid (TCA) Cycle of Salmonella enterica Serovar Typhimurium  

PubMed Central

Host nitric oxide (NO·) production is important for controlling intracellular bacterial pathogens including Salmonella enterica serovar Typhimurium but the underlying mechanisms are incompletely understood. S. Typhmurium 14028s is prototrophic for all amino acids but cannot synthesize Methionine (M) or Lysine (K) during nitrosative stress. Here we show that NO·-induced MK auxotrophy results from reduced succinyl-CoA availability as a consequence of NO· targeting of lipoamide-dependent lipoamide dehydrogenase (LpdA) activity. LpdA is an essential component of the pyruvate and ?-ketoglutarate dehydrogenase complexes. Additional effects of NO· on gene regulation prevent compensatory pathways of succinyl-CoA production. Microarray analysis indicates that over 50% of the transcriptional response of S. Typhimurium to nitrosative stress is attributable to LpdA inhibition. Bacterial methionine transport is essential for virulence in NO·-producing mice, demonstrating that NO·-induced MK auxotrophy occurs in vivo. These observations underscore the importance of metabolic targets for antimicrobial actions of NO·. PMID:21767810

Richardson, Anthony R.; Payne, Elizabeth C.; Younger, Noah; Karlinsey, Joyce E.; Thomas, Vinai C.; Becker, Lynne A.; Navarre, William W.; Castor, Margaret E.; Libby, Stephen J.; Fang, Ferric C.

2011-01-01

52

Cell cycle regulation of centromere function in Saccharomyces cerevisiae  

SciTech Connect

Accurate transmission of eukaryotic chromosomes is dependent on a specialized region of the chromosome, the centromere. The centromere is the site of assembly of the kinetochore, an integrated protein/DNA complex which acts as the point of attachment between individual chromosomes and the mitotic spindle. The presence of more than one centromere on a single chromosome (dicentric chromosome) is deleterious, resulting in broken chromosome derivatives and unstable chromosome inheritance. Dicentric chromosomes were first studied extensively in Zea mays. Cytogenetic observations of the mitotic behavior of these chromosomes illustrates a sequence of events termed a breakage-fusion-bridge cycle. When the two centromeres of a single chromosome are pulled to opposite poles during mitosis, the resulting anaphase bridge which forms between them is often broken. The broken ends are highly reactive, and by fusing with other chromsomes produce a number of chromosomal anomalies, including deletions, translocations, and the regeneration of dicentric chromosomes. This cycle persists until stable rearrangements are formed.

Brock, J.A.; Bloom, K. [Univ. of North Carolina, Chapel Hill, NC (United States)

1993-12-31

53

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

54

Alternative Functions of Core Cell Cycle Regulators in Neuronal Migration, Neuronal Maturation, and Synaptic Plasticity  

E-print Network

Recent studies have demonstrated that boundaries separating a cycling cell from a postmitotic neuron are not as concrete as expected. Novel and unique physiological functions in neurons have been ascribed for proteins ...

Frank, Christopher Lee

55

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

56

High cycle fatigue behaviour of functional spinal units.  

PubMed

Vibrations have been shown to be an important risk factor for spinal pathologies. The underlying mechanisms are poorly understood and in vivo data scarce and difficult to obtain. Consequently numerical models are used to estimate spinal loading; requiring fatigue strength information, which was obtained in this study for spinal specimens from young and old male donors of working age in vitro. Bone mineral density (BMD) and endplate area were determined using CT scans. Three groups were investigated: young specimens in neutral posture, young in flexed posture, and old in neutral posture. The loading consisted of 300,000 sinusoidal compression cycles of 2 kN, inducing a nucleus pressure peek of approximately 1.4 MPa. No failure of the young specimens in neutral posture was observed, but four specimens from older donors with low BMD failed. The product between endplate area and BMD was shown to be useful to predict fatigue strength for old donors and should therefore be considered with regard to whole body vibration injuries. In flexed posture, two specimens from young donors failed. One failure can be attributed to low BMD following the trend for the old specimens; the other failure could not be explained, leaving the influence of flexion yet unclear. PMID:20953072

Huber, Gerd; Skrzypiec, Daniel M; Klein, Anke; Püschel, Klaus; Morlock, Michael M

2010-01-01

57

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

58

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

59

GHRS Side 2 Carrousel Functional Test -- Cycle 4  

NASA Astrophysics Data System (ADS)

The rate of occurrence of GHRS carrousel reset events seems to have increased over the last six months. This test will repeat the carrousel functional test which was run during OV to help determine if there is any change in carrousel response. Engineering data from this test will be compared to data taken during OV to attempt to measure any change in carrousel rate of rotation, current draw and settling time. A degradation in carrousel per- formance could help explain the increased rate of reset events.

Skapik, Joe

1994-01-01

60

The Role of ATP in the Functional Cycle of the DnaK Chaperone System  

Microsoft Academic Search

Hsp 70 chaperons interact with protein substrates in an ATP-dependent manner to prevent aggregation and promote protein folding. For theEscherichia colihomolog DnaK, we have characterized the ATP hydrolysis cycle as well as the effects of the DnaJ and GrpE cofactors on substrate interaction to reach conclusions on the functional cycle. DnaK ATPase was stimulated by substrates (ninefold) and DnaJ (13-fold)

John S. McCarty; Alexander Buchberger; Jochen Reinstein; Bernd Bukau

1995-01-01

61

Using Mutant Cycle Analysis to Elucidate Long-Range Functional Coupling in Allosteric Receptors  

PubMed Central

The functional coupling of residues that are far apart in space is the quintessential property of allosteric receptors. Data from functional studies of allosteric receptors, such as whole-cell dose-response relations, can be used to determine if mutation to a receptor significantly impacts agonist potency. However, the classification of perturbations as primarily impacting binding or allosteric function is more challenging, often requiring detailed kinetic studies. This protocol describes a simple strategy, derived from mutant cycle analysis, for elucidating long-range functional coupling in allosteric receptors (ELFCAR). Introduction of a gain-of-function reporter mutation, followed by a mutant cycle analysis of the readily-measured macroscopic EC50 values can provide insight into the role of many physically distant targets. This new method should find broad application in determining the functional roles of residues in allosteric receptors. PMID:22052487

Shanata, Jai A. P.; Frazier, Shawnalea J.; Lester, Henry A.; Dougherty, Dennis A.

2014-01-01

62

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

63

The multiple hats of Vasa function and its regulation of cell cycle progression  

PubMed Central

Summary Vasa, an ATP-dependent RNA helicase, is broadly conserved among various organisms from cnidarians to mammals. It has a rich history of utility as a germline marker, and is believed to function as a positive translational regulator in the determination and maintenance of germline cells. Studies in non-model organisms, however, revealed that Vasa is also present in somatic cells of many tissues. In many cases these cells are multipotent, are non-germline associated, and give rise to a variety of different tissue types. Recent work now also demonstrates that Vasa functions in the regulation of the cell cycle. Here we discuss this newly described function of Vasa in mitotic and meiotic cell cycles, and we address the conundrum created within these observations, that is, that most cells are mitotically independent of Vasa, yet when Vasa is present in a cell, it appears to be essential for cell cycle progression. PMID:21823188

Yajima, Mamiko; Wessel, Gary M.

2011-01-01

64

Functional microarray analysis of nitrogen and carbon cycling genes across an Antarctic latitudinal transect.  

PubMed

Soil-borne microbial communities were examined via a functional gene microarray approach across a southern polar latitudinal gradient to gain insight into the environmental factors steering soil N- and C-cycling in terrestrial Antarctic ecosystems. The abundance and diversity of functional gene families were studied for soil-borne microbial communities inhabiting a range of environments from 51 degrees S (cool temperate-Falkland Islands) to 72 degrees S (cold rock desert-Coal Nunatak). The recently designed functional gene array used contains 24,243 oligonucleotide probes and covers >10,000 genes in >150 functional groups involved in nitrogen, carbon, sulfur and phosphorus cycling, metal reduction and resistance and organic contaminant degradation (He et al. 2007). The detected N- and C-cycle genes were significantly different across different sampling locations and vegetation types. A number of significant trends were observed regarding the distribution of key gene families across the environments examined. For example, the relative detection of cellulose degradation genes was correlated with temperature, and microbial C-fixation genes were more present in plots principally lacking vegetation. With respect to the N-cycle, denitrification genes were linked to higher soil temperatures, and N2-fixation genes were linked to plots mainly vegetated by lichens. These microarray-based results were confirmed for a number of gene families using specific real-time PCR, enzymatic assays and process rate measurements. The results presented demonstrate the utility of an integrated functional gene microarray approach in detecting shifts in functional community properties in environmental samples and provide insight into the forces driving important processes of terrestrial Antarctic nutrient cycling. PMID:18043626

Yergeau, Etienne; Kang, Sanghoon; He, Zhili; Zhou, Jizhong; Kowalchuk, George A

2007-06-01

65

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

66

Functional microarray analysis of nitrogen and carbon cycling genes across an Antarctic latitudinal transect  

Microsoft Academic Search

Soil-borne microbial communities were examined via a functional gene microarray approach across a southern polar latitudinal gradient to gain insight into the environmental factors steering soil N- and C-cycling in terrestrial Antarctic ecosystems. The abundance and diversity of functional gene families were studied for soil-borne microbial communities inhabiting a range of environments from 51°S (cool temperate – Falkland Islands) to

Etienne Yergeau; Sanghoon Kang; Zhili He; Jizhong Zhou; George A Kowalchuk

2007-01-01

67

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

68

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

69

Site-selective hexa-hetero-functionalization of ?-cyclodextrin an archetypical C?-symmetric concave cycle.  

PubMed

Access to Cn (n>4) symmetric cyclic concave molecules with a different function on each of their n subunits is an unmet challenge. The reason lies in the lack of a post-functionalization method whose site selectivity is sufficiently understood, predictable and modulable to access most functionalization patterns. Here we disclose a new site-directing rule for a debenzylation reaction on cyclodextrins that solves this problem and allows the unprecedented access to penta- and ultimately hexa-differentiations of such C6 concave cycles. This achievement opens the access to objects with very high-density information. PMID:25382259

Wang, Bo; Zaborova, Elena; Guieu, Samuel; Petrillo, Marta; Guitet, Maxime; Blériot, Yves; Ménand, Mickaël; Zhang, Yongmin; Sollogoub, Matthieu

2014-01-01

70

Computational estimation of tricarboxylic acid cycle fluxes using noisy NMR data from cardiac biopsies  

PubMed Central

Background The aerobic energy metabolism of cardiac muscle cells is of major importance for the contractile function of the heart. Because energy metabolism is very heterogeneously distributed in heart tissue, especially during coronary disease, a method to quantify metabolic fluxes in small tissue samples is desirable. Taking tissue biopsies after infusion of substrates labeled with stable carbon isotopes makes this possible in animal experiments. However, the appreciable noise level in NMR spectra of extracted tissue samples makes computational estimation of metabolic fluxes challenging and a good method to define confidence regions was not yet available. Results Here we present a computational analysis method for nuclear magnetic resonance (NMR) measurements of tricarboxylic acid (TCA) cycle metabolites. The method was validated using measurements on extracts of single tissue biopsies taken from porcine heart in vivo. Isotopic enrichment of glutamate was measured by NMR spectroscopy in tissue samples taken at a single time point after the timed infusion of 13C labeled substrates for the TCA cycle. The NMR intensities for glutamate were analyzed with a computational model describing carbon transitions in the TCA cycle and carbon exchange with amino acids. The model dynamics depended on five flux parameters, which were optimized to fit the NMR measurements. To determine confidence regions for the estimated fluxes, we used the Metropolis-Hastings algorithm for Markov chain Monte Carlo (MCMC) sampling to generate extensive ensembles of feasible flux combinations that describe the data within measurement precision limits. To validate our method, we compared myocardial oxygen consumption calculated from the TCA cycle flux with in vivo blood gas measurements for 38 hearts under several experimental conditions, e.g. during coronary artery narrowing. Conclusions Despite the appreciable NMR noise level, the oxygen consumption in the tissue samples, estimated from the NMR spectra, correlates with blood-gas oxygen uptake measurements for the whole heart. The MCMC method provides confidence regions for the estimated metabolic fluxes in single cardiac biopsies, taking the quantified measurement noise level and the nonlinear dependencies between parameters fully into account. PMID:23965343

2013-01-01

71

Gene expression signatures but not cell cycle checkpoint functions distinguish AT carriers from normal individuals  

PubMed Central

Ataxia telangiectasia (AT) is a rare autosomal recessive disease caused by mutations in the ataxia telangiectasia-mutated gene (ATM). AT carriers with one mutant ATM allele are usually not severely affected although they carry an increased risk of developing cancer. There has not been an easy and reliable diagnostic method to identify AT carriers. Cell cycle checkpoint functions upon ionizing radiation (IR)-induced DNA damage and gene expression signatures were analyzed in the current study to test for differential responses in human lymphoblastoid cell lines with different ATM genotypes. While both dose- and time-dependent G1 and G2 checkpoint functions were highly attenuated in ATM?/? cell lines, these functions were preserved in ATM+/? cell lines equivalent to ATM+/+ cell lines. However, gene expression signatures at both baseline (consisting of 203 probes) and post-IR treatment (consisting of 126 probes) were able to distinguish ATM+/? cell lines from ATM+/+ and ATM?/? cell lines. Gene ontology (GO) and pathway analysis of the genes in the baseline signature indicate that ATM function-related categories, DNA metabolism, cell cycle, cell death control, and the p53 signaling pathway, were overrepresented. The same analyses of the genes in the IR-responsive signature revealed that biological categories including response to DNA damage stimulus, p53 signaling, and cell cycle pathways were overrepresented, which again confirmed involvement of ATM functions. The results indicate that AT carriers who have unaffected G1 and G2 checkpoint functions can be distinguished from normal individuals and AT patients by expression signatures of genes related to ATM functions. PMID:23943852

Zhang, Liwen; Simpson, Dennis A.; Innes, Cynthia L.; Chou, Jeff; Bushel, Pierre R.; Paules, Richard S.; Kaufmann, William K.

2013-01-01

72

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

73

Integrative Functional Genomics of Hepatitis C Virus Infection Identifies Host Dependencies in Complete Viral Replication Cycle  

PubMed Central

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

2014-01-01

74

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

75

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

76

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

77

HESS Opinions "Biological catalysis of the hydrological cycle: life's thermodynamic function"  

NASA Astrophysics Data System (ADS)

Darwinian theory depicts life as being overwhelmingly consumed by a fight for survival in a hostile environment. However, from a thermodynamic perspective, life is a dynamic, out of equilibrium process, stabilizing and coevolving in concert with its abiotic environment. The living components of the biosphere on the Earth's surface of greatest biomass, the plants and cyanobacteria, are involved in the transpiration of a vast amount of water. Transpiration is part of the global water cycle, and it is this cycle that distinguishes Earth from its apparently life-barren neighboring planets, Venus and Mars. The dissipation of sunlight into heat by organic molecules in the biosphere, and its coupling to the water cycle (as well as other abiotic processes), is by far the greatest entropy-producing process occurring on Earth. Life, from this perspective, can be viewed as performing an important thermodynamic function, acting as a dynamic catalyst by aiding irreversible abiotic processes such as the water cycle, hurricanes, and ocean and wind currents to produce entropy. The role of animals in this view is that of unwitting but dedicated servants of the plants and cyanobacteria, helping them to grow, and to spread into initially inhospitable areas.

Michaelian, K.

2012-08-01

78

Abnormal tricarboxylic acid cycle metabolites in isovaleric acidaemia  

Microsoft Academic Search

Summary\\u000a Background  Although a number of abnormal diagnostic metabolites have previously been described in the urine of patients with isovaleric\\u000a acidaemia (IVA), they do not fully explain the clinical symptoms associated with this disease.\\u000a \\u000a \\u000a \\u000a Methods  On the basis of our current understanding of the TCA cycle and IVA, we predicted a number of abnormal methylated TCA cycle\\u000a metabolites, initiated by methylsuccinic acid.

D. T. Loots

2009-01-01

79

Role of the kinetochore/cell cycle checkpoint protein ZW10 in interphase cytoplasmic dynein function  

PubMed Central

Zeste white 10 (ZW10) is a mitotic checkpoint protein and the anchor for cytoplasmic dynein at mitotic kinetochores, though it is expressed throughout the cell cycle. We find that ZW10 localizes to pericentriolar membranous structures during interphase and cosediments with Golgi membranes. Dominant-negative ZW10, anti-ZW10 antibody, and ZW10 RNA interference (RNAi) caused Golgi dispersal. ZW10 RNAi also dispersed endosomes and lysosomes. Live imaging of Golgi, endosomal, and lysosomal markers after reduced ZW10 expression showed a specific decrease in the frequency of minus end–directed movements. Golgi membrane–associated dynein was markedly decreased, suggesting a role for ZW10 in dynein cargo binding during interphase. We also find ZW10 enriched at the leading edge of migrating fibroblasts, suggesting that ZW10 serves as a general regulator of dynein function throughout the cell cycle. PMID:16505164

Varma, Dileep; Dujardin, Denis L.; Stehman, Stephanie A.; Vallee, Richard B.

2006-01-01

80

Energy-containing beverages: reproductive hormones and ovarian function in the BioCycle Study123  

PubMed Central

Background: Energy-containing beverages are widely consumed among premenopausal women, but their association with reproductive hormones is not well understood. Objective: The objective was to assess the association of energy-containing beverages, added sugars, and total fructose intake with reproductive hormones among ovulatory cycles and sporadic anovulation in healthy premenopausal women. Design: Women (n = 259) in the BioCycle Study were followed for up to 2 menstrual cycles; they provided fasting blood specimens during up to 8 visits/cycle and four 24-h dietary recalls/cycle. Results: Women who consumed ?1 cup (1 cup = 237 mL) sweetened soda/d had 16.3% higher estradiol concentrations compared with women who consumed less sweetened soda (86.5 pg/mL compared with 74.4 pg/mL, P = 0.01) after adjustment for age, BMI, race, dietary factors, and physical activity. Similarly elevated estradiol concentrations were found for ?1 cup cola/d and noncola soda intake. Neither artificially sweetened soda nor fruit juice intake ?1 cup/d was significantly associated with reproductive hormones. Added sugar above the average US woman's intake (?73.2 g/d) or above the 66th percentile in total fructose intake (?41.5 g/d) was associated with significantly elevated estradiol but not consistently across all models. No associations were found between beverages, added sugars, or total fructose intake and anovulation after multivariate adjustment. Conclusions: Even at moderate consumption amounts, sweetened soda is associated with elevated follicular estradiol concentrations among premenopausal women but does not appear to affect ovulatory function. Further research into the mechanism driving the association between energy-containing beverages and reproductive hormones, and its potential implications for women's health, is warranted. PMID:23364018

Schliep, Karen C; Mumford, Sunni L; Pollack, Anna Z; Perkins, Neil J; Ye, Aijun; Zhang, Cuilin J; Stanford, Joseph B; Porucznik, Christina A; Hammoud, Ahmad O; Wactawski-Wende, Jean

2013-01-01

81

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

PubMed Central

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

2013-01-01

82

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

83

Variable Sun-Earth energy coupling function: dependence on solar cycle strength  

NASA Astrophysics Data System (ADS)

Correlation between monthly geomagnetic activity and monthly sunspot numbers for more than 50 years revealed that the geomagnetic activity during the current solar maximum is lower than what can be expected from the sunspot numbers. This is valid for both one station (Kiruna K index, since 1962) and world-wide average (Kp index, since 1932). The Kp data with more than 80 years record also revealed that monthly Kp for given sunspot numbers are lower during solar cycles with small amplitude than those with large amplitude when we define the cycle from the end of solar maximum to the end of next solar maximum. The result suggests that the Sun-Earth coupling function itself (including the multiplication constant) might be different between different solar cycles when the amplitude is different, and therefore that there might be unknown solar parameter that should contribute to the Sun-Earth coupling. Such a hidden parameter might bridge missing physical link between the solar effect and the terrestrial environment such as the global temperature. Acknowledgement: Kp is an official IAGA endorsed index that is provided by GFZ, Adolf-Schmidt-Observatory Niemegk, Germany. The sunspot numbers are provided by Royal Observatory of Belgium, Brussels.

Yamauchi, Masatoshi

2014-05-01

84

The roles of predator maturation delay and functional response in determining the periodicity of predator-prey cycles.  

PubMed

Population cycles in small mammals have attracted the attention of several generations of theoretical and experimental biologists and continue to generate controversy. Top-down and bottom-up trophic regulations are two recent competing hypotheses. The principal purpose of this paper is to explore the relative contributions of a variety of ecological factors to predator-prey population cycles. Here we suggest that for some species - collared lemmings, snowshoe hares and moose in particular - maturation delay of predators and the functional response of predation appear to be the primary determinants. Our study suggests that maturation delay alone almost completely determines the cycle period, whereas the functional response greatly affects its amplitude and even its existence. These results are obtained from sensitivity analysis of all parameters in a mathematical model of the lemming-stoat delayed system, which is an extension of Gilg's model. Our result may also explain why lemmings have a 4-year cycle whereas snowshoe hares have a 10-year cycle. Our parameterized model supports and extends May's assertion that time delay impacts cycle period and amplitude. Furthermore, if maturation periods of predators are too short or too long, or the functional response resembles Holling Type I, then population cycles do not appear; however, suitable intermediate predator maturation periods and suitable functional responses can generate population cycles for both prey and predators. These results seem to explain why some populations are cyclic whereas others are not. Finally, we find parameterizations of our model that generate a 38-year population cycle consistent with the putative cycles of the moose-wolf interactions on Isle Royale, Michigan. PMID:19563815

Wang, Hao; Nagy, John D; Gilg, Olivier; Kuang, Yang

2009-09-01

85

Sexuality of alcoholic women with menstrual cycle function: effects of duration of alcohol abstinence.  

PubMed

Although improvement in sexual function has been reported to occur in postmenopausal alcoholic women after long-term sobriety, little is known about the role alcohol abstinence may play in terms of improving sexual functioning in alcoholic women with menstrual cycle function. The responses of 58 menstruating alcoholic Italian women to a standardized questionnaire that included questions related to sexual function, behavior, and performance are reported. Women were categorized as alcohol abstinent (AA) for > 1 year (long AA, n = 22) or < 1 year (short AA, n = 36). In both groups, 100% reported that they had a regular sexual partner, and the response rate to the sexuality questions was > 99%. Compared with short AA women, long AA women were significantly older at the time of study, at menarche, and at onset of heavy drinking, alcohol dependence, and alcohol abstinence. Sexual desire was defined as willingness to engage in sexual activity; sexual capacity was defined as the ability to become sexually aroused; sexual responsiveness was defined as the ability to achieve orgasm. On all three measures, ts well as intercourse frequency, both long AA and short AA women improved significantly with alcohol abstinence. These findings suggest that sobriety, even of relatively short duration, improves sexual function in menstruating alcoholic women. PMID:8214413

Gavaler, J S; Rizzo, A; Rossaro, L; Van Thiel, D H; Brezza, E; Deal, S R

1993-08-01

86

Phosphorylation regulates VCIP135 function in Golgi membrane fusion during the cell cycle.  

PubMed

The Golgi apparatus in mammalian cells consists of stacks that are often laterally linked into a ribbon-like structure. During cell division, the Golgi disassembles into tubulovesicular structures in the early stages of mitosis and reforms in the two daughter cells by the end of mitosis. Valosin-containing protein p97-p47 complex-interacting protein, p135 (VCIP135), an essential factor involved in p97-mediated membrane fusion pathways, is required for postmitotic Golgi cisternae regrowth and Golgi structure maintenance in interphase. However, how VCIP135 function is regulated in the cell cycle remains unclear. Here, we report that VCIP135 depletion by RNA interference results in Golgi fragmentation. VCIP135 function requires membrane association and p97 interaction, both of which are inhibited in mitosis by VCIP135 phosphorylation. We found that wild-type VCIP135, but not its phosphomimetic mutants, rescues Golgi structure in VCIP135-depleted cells. Our results demonstrate that VCIP135 phosphorylation regulates its Golgi membrane association and p97 interaction, and thus contributes to the tight control of the Golgi disassembly and reassembly process during the cell cycle. PMID:24163436

Zhang, Xiaoyan; Zhang, Honghao; Wang, Yanzhuang

2014-01-01

87

A Kinase-Independent Function of CDK6 Links the Cell Cycle to Tumor Angiogenesis  

PubMed Central

Summary In contrast to its close homolog CDK4, the cell cycle kinase CDK6 is expressed at high levels in lymphoid malignancies. In a model for p185BCR-ABL+ B-acute lymphoid leukemia, we show that CDK6 is part of a transcription complex that induces the expression of the tumor suppressor p16INK4a and the pro-angiogenic factor VEGF-A. This function is independent of CDK6’s kinase activity. High CDK6 expression thus suppresses proliferation by upregulating p16INK4a, providing an internal safeguard. However, in the absence of p16INK4a, CDK6 can exert its full tumor-promoting function by enhancing proliferation and stimulating angiogenesis. The finding that CDK6 connects cell-cycle progression to angiogenesis confirms CDK6’s central role in hematopoietic malignancies and could underlie the selection pressure to upregulate CDK6 and silence p16INK4a. PMID:23948297

Kollmann, Karoline; Heller, Gerwin; Schneckenleithner, Christine; Warsch, Wolfgang; Scheicher, Ruth; Ott, Rene G.; Schäfer, Markus; Fajmann, Sabine; Schlederer, Michaela; Schiefer, Ana-Iris; Reichart, Ursula; Mayerhofer, Matthias; Hoeller, Christoph; Zöchbauer-Müller, Sabine; Kerjaschki, Dontscho; Bock, Christoph; Kenner, Lukas; Hoefler, Gerald; Freissmuth, Michael; Green, Anthony R.; Moriggl, Richard; Busslinger, Meinrad; Malumbres, Marcos; Sexl, Veronika

2013-01-01

88

Function of Trehalose and Glycogen in Cell Cycle Progression and Cell Viability in Saccharomyces cerevisiae  

PubMed Central

Trehalose and glycogen accumulate in Saccharomyces cerevisiae when growth conditions deteriorate. It has been suggested that aside from functioning as storage factors and stress protectants, these carbohydrates may be required for cell cycle progression at low growth rates under carbon limitation. By using a mutant unable to synthesize trehalose and glycogen, we have investigated this requirement of trehalose and glycogen under carbon-limited conditions in continuous cultures. Trehalose and glycogen levels increased with decreasing growth rates in the wild-type strain, whereas no trehalose or glycogen was detected in the mutant. However, the mutant was still able to grow and divide at low growth rates with doubling times similar to those for the wild-type strain, indicating that trehalose and glycogen are not essential for cell cycle progression. Nevertheless, upon a slight increase of extracellular carbohydrates, the wild-type strain degraded its reserve carbohydrates and was able to enter a cell division cycle faster than the mutant. In addition, wild-type cells survived much longer than the mutant cells when extracellular carbon was exhausted. Thus, trehalose and glycogen have a dual role under these conditions, serving as storage factors during carbon starvation and providing quickly a higher carbon and ATP flux when conditions improve. Interestingly, the CO2 production rate and hence the ATP flux were higher in the mutant than in the wild-type strain at low growth rates. The possibility that the mutant strain requires this steady higher glycolytic flux at low growth rates for passage through Start is discussed. PMID:9882651

Silljé, H. H. W.; Paalman, J. W. G.; ter Schure, E. G.; Olsthoorn, S. Q. B.; Verkleij, A. J.; Boonstra, J.; Verrips, C. T.

1999-01-01

89

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

90

Q-site inhibitor induced ROS production of mitochondrial complex II is attenuated by TCA cycle dicarboxylates.  

PubMed

The impact of complex II (succinate:ubiquinone oxidoreductase) on the mitochondrial production of reactive oxygen species (ROS) has been underestimated for a long time. However, recent studies with intact mitochondria revealed that complex II can be a significant source of ROS. Using submitochondrial particles from bovine heart mitochondria as a system that allows the precise setting of substrate concentrations we could show that mammalian complex II produces ROS at subsaturating succinate concentrations in the presence of Q-site inhibitors like atpenin A5 or when a further downstream block of the respiratory chain occurred. Upon inhibition of the ubiquinone reductase activity, complex II produced about 75% hydrogen peroxide and 25% superoxide. ROS generation was attenuated by all dicarboxylates that are known to bind competitively to the substrate binding site of complex II, suggesting that the oxygen radicals are mainly generated by the unoccupied flavin site. Importantly, the ROS production induced by the Q-site inhibitor atpenin A5 was largely unaffected by the redox state of the Q pool and the activity of other respiratory chain complexes. Hence, complex II has to be considered as an independent source of mitochondrial ROS in physiology and pathophysiology. PMID:23800966

Siebels, Ilka; Dröse, Stefan

2013-10-01

91

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

E-print Network

the enzyme phosphoenolpyruvate synthase (Pps) has increased the yield of the aromatic precursor 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) from glucose by two- fold compared to previous methods. In this study, Pps overexpression is again applied...

Spitzer, Richard G.

2012-06-07

92

2-Phenyl-beta-lapachone can affect mitochondrial function by redox cycling mediated oxidation.  

PubMed

2-Phenyl-beta-lapachone (3,4-dihydro-2-methyl-2-phenyl-2H-naphtho[1,2b]pyran-5,6-dione) (2PBL) is a o-naphthoquinone synthesized as a possible antitumoral agent. The addition of micromolar concentrations of 2PBL to rat liver mitochondria (in the presence of malate-glutamate or succinate, as respiratory substrates): (1) stimulated O(2) consumption in state 4 and inhibited O(2) consumption in state 3, thus decreasing respiratory control index (RCI); and (2) collapsed the mitochondrial membrane potential. The addition of 2PBL to rat liver submitochondrial particles: (1) stimulated NADH oxidation in the presence of rotenone, antimycin, myxothiazol or cyanide; (2) stimulated (.-)O(2)(-) production in the presence of NADH and antimycin; and (3) led to 2PBL semiquinone radical production. Control studies carried out with two p-naphthoquinones, menadione and atovaquone, did not produced equivalent effects. These findings support the hypothesis that 2PBL, undergoes redox cycling and affects mitochondrial function. The 2PBL effect is complex, involving inhibition of electron transfer, uncoupling of oxidative phosphorylation, collapse of mitochondrial membrane potential and (.-)O(2)(-) production by redox cycling. The mitochondrion could be a target organelle for 2PBL cytotoxicity. PMID:15542051

de Witte, Natacha V; Stoppani, Andrés O M; Dubin, Marta

2004-12-15

93

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

94

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

95

Targeted Disruption of the Murine Retinal Dehydrogenase Gene Rdh12 Does Not Limit Visual Cycle Function?  

PubMed Central

RDH12 codes for a member of the family of short-chain alcohol dehydrogenases/reductases proposed to function in the visual cycle that supplies the chromophore 11-cis retinal to photoreceptor cells. Mutations in RDH12 cause severe and progressive childhood onset autosomal-recessive retinal dystrophy, including Leber congenital amaurosis. We generated Rdh12 knockout mice, which exhibited grossly normal retinal histology at 10 months of age. Levels of all-trans and 11-cis retinoids in dark- and light-adapted animals and scotopic and photopic electroretinogram (ERG) responses were similar to those for the wild type, as was recovery of the ERG response following bleaching, for animals matched for an Rpe65 polymorphism (p.L450M). Lipid peroxidation products and other measures of oxidative stress did not appear to be elevated in Rdh12?/? animals. RDH12 was localized to photoreceptor inner segments and the outer nuclear layer in both mouse and human retinas by immunohistochemistry. The present findings, together with those of earlier studies showing only minor functional deficits in mice deficient for Rdh5, Rdh8, or Rdh11, suggest that the activity of any one isoform is not rate limiting in the visual response. PMID:17130236

Kurth, Ingo; Thompson, Debra A.; Rüther, Klaus; Feathers, Kecia L.; Chrispell, Jared D.; Schroth, Jana; McHenry, Christina L.; Schweizer, Michaela; Skosyrski, Sergej; Gal, Andreas; Hübner, Christian A.

2007-01-01

96

Regulatory Roles of Junctin in Sarcoplasmic Reticulum Calcium Cycling and Myocardial Function  

PubMed Central

Junctin (JCN), a 26-kd sarcoplasmic reticulum (SR) transmembrane protein, forms a quaternary protein complex with the ryanodine receptor, calsequestrin, and triadin in the SR lumen of cardiac muscle. Within this complex, calsequestrin, triadin, and JCN appear to be critical for normal regulation of ryanodine receptor–mediated calcium (Ca) release. Junctin and triadin exhibit 60% to 70% amino acid homology in their transmembrane domains, including repeated KEKE motifs important for macromolecular protein-protein interactions within their SR luminal tails. Recent studies have uncovered functional roles of both JCN and triadin in the mouse heart, using transgenic overexpression strategies, which exhibit varying phenotypes including mild SR structural alterations, prolongation of Ca transient decay, impaired relaxation, and cardiac hypertrophy and/or heart failure. More specifically, both in vitro adenoviral gene transfer and in vivo gene-targeting techniques to manipulate JCN expression levels have shown that JCN is an essential factor in maintaining normal cardiac Ca handling and cardiac function. This article reviews the new findings on the regulatory roles of JCN in cardiac SR Ca cycling and contractility, with special emphasis on the effects of JCN ablation on delayed afterdepolarization-induced arrhythmias and premature mortality in mouse models. PMID:18206802

Fan, Guo-Chang; Yuan, Qunying; Kranias, Evangelia G.

2008-01-01

97

Intellectual, adaptive, and behavioral functioning in children with urea cycle disorders.  

PubMed

Inborn errors of urea synthesis lead to an accumulation of ammonia in blood and brain and result in high rates of mortality and neurodevelopmental disability. This study seeks to characterize the cognitive, adaptive, and emotional/behavioral functioning of children with urea cycle disorders (UCDs). These domains were measured through testing and parent questionnaires in 92 children with UCDs [33 neonatal onset (NO), 59 late onset (LO)]. Results indicate that children who present with NO have poorer outcome than those who present later in childhood. Approximately half of the children with NO performed in the range of intellectual disability (ID), including a substantial number ( approximately 30%) who were severely impaired. In comparison, only a quarter of the LO group was in the range of ID. There is also evidence that the UCD group has difficulties in aspects of emotional/behavioral and executive skills domains. In conclusion, children with UCDs present with a wide spectrum of cognitive outcomes. Children with NO disease have a much higher likelihood of having an ID, which becomes even more evident with increasing age. However, even children with LO UCDs demonstrate evidence of neurocognitive and behavioral impairment, particularly in aspects of attention and executive functioning. PMID:19287347

Krivitzky, Lauren; Babikian, Talin; Lee, Hye-Seung; Thomas, Nina Hattiangadi; Burk-Paull, Karen L; Batshaw, Mark L

2009-07-01

98

Intellectual, Adaptive, and Behavioral Functioning in Children with Urea Cycle Disorders  

PubMed Central

Inborn errors of urea synthesis lead to an accumulation of ammonia in blood and brain, and result in high rates of mortality and neurodevelopmental disability. The current study seeks to characterize the cognitive, adaptive, and emotional/behavioral functioning of children with Urea Cycle Disorders (UCDs). These domains were measured through testing and parent questionnaires in 92 children with UCDs (33 neonatal onset, 59 late onset). Results indicate that children who present with neonatal onset have poorer outcome than those who present later in childhood. Approximately half of the children with neonatal onset performed in the range of intellectual disability (ID), including a substantial number (~30%) who were severely impaired. In comparison, only a quarter of the late onset group were in the range of ID. There is also evidence that the UCD group has difficulties in aspects of emotional/behavioral and executive skills domains. In conclusion, children with UCDs present with a wide spectrum of cognitive outcomes. Children with neonatal onset disease have a much higher likelihood of having an intellectual disability, which becomes even more evident with increasing age. However, even children with late onset UCDs demonstrate evidence of neurocognitive and behavioral impairment, particularly in aspects of attention and executive functioning. PMID:19287347

Krivitzky, Lauren; Babikian, Talin; Lee, HyeSeung; Thomas, Nina Hattiangadi; Burk-Paull, Karen L.; Batshaw, Mark L.

2009-01-01

99

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

100

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

101

Intravenous administration of Honokiol provides neuroprotection and improves functional recovery after traumatic brain injury through cell cycle inhibition.  

PubMed

Recently, increasing evidence has shown that cell cycle activation is a key factor of neuronal death and neurological dysfunction after traumatic brain injury (TBI). This study aims to investigate the effects of Honokiol, a cell cycle inhibitor, on attenuating the neuronal damage and facilitating functional recovery after TBI in rats, in an attempt to unveil its underlying molecular mechanisms in TBI. This study suggested that delayed intravenous administration of Honokiol could effectively ameliorate TBI-induced sensorimotor and cognitive dysfunctions. Meanwhile, Honokiol treatment could also reduce the lesion volume and increase the neuronal survival in the cortex and hippocampus. The neuronal degeneration and apoptosis in the cortex and hippocampus were further significantly attenuated by Honokiol treatment. In addition, the expression of cell cycle-related proteins, including cyclin D1, CDK4, pRb and E2F1, was significantly increased and endogenous cell cycle inhibitor p27 was markedly decreased at different time points after TBI. And these changes were significantly reversed by post-injury Honokiol treatment. Furthermore, the expression of some of the key cell cycle proteins such as cyclin D1 and E2F1 and the associated apoptosis in neurons were both remarkably attenuated by Honokiol treatment. These results show that delayed intravenous administration of Honokiol could effectively improve the functional recovery and attenuate the neuronal cell death, which is probably, at least in part, attributed to its role as a cell cycle inhibitior. This might give clues to developing attractive therapies for future clinical trials. PMID:24973706

Wang, Haiquan; Liao, Zhengbu; Sun, Xiaochuan; Shi, Quanhong; Huo, Gang; Xie, Yanfeng; Tang, Xiaolan; Zhi, Xinggang; Tang, Zhaohua

2014-11-01

102

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

103

Diosmin pretreatment improves cardiac function and suppresses oxidative stress in rat heart after ischemia/reperfusion.  

PubMed

Reperfusion of ischemic tissue leads to the generation of oxygen derived free radicals which plays an important role in cellular damage. Objective of the current study is to evaluate the cardio-protective and antioxidant effect of diosmin on ischemia-reperfusion related cardiac dysfunction, oxidative stress and apoptosis. Diosmin (50 and 100 mg/kg body weight (bw)) was given every day to the rats orally throughout the experimental period. Ischemia/reperfusion protocol was carried out ex vivo using langendorff perfusion method and the cardiac functional recovery was assessed in terms of percentage rate pressure product. Coronary effluents of LDH and CK-MB activities, antioxidant enzyme activities, lipid peroxidation products, activity of TCA cycle enzymes were evaluated. Moreover, in vitro superoxide anion and hydroxyl radical scavenging potential of diosmin was also quantified. Finally, quantitative real-time PCR was used for assessing Bcl-2 mRNA expression in heart. Cardiac functional recovery was impaired after reperfusion compared with continuously perfused heart. It was significantly prevented by diosmin treatment. Impaired antioxidant enzyme activities and elevated lipid peroxidation products level were also significantly suppressed. The activity of TCA cycle enzymes was protected against reperfusion stress. Down regulated Bcl-2 was also significantly increased. This study concluded that diosmin pretreatment prevents all the impaired patterns including cardiac function, oxidative stress and apoptosis associated with reperfusion in control heart by its antioxidant role. PMID:24769512

Senthamizhselvan, Oomaidurai; Manivannan, Jeganathan; Silambarasan, Thangarasu; Raja, Boobalan

2014-08-01

104

Proteasome Function Is Required for Biological Timing throughout the Twenty-Four Hour Cycle  

PubMed Central

Summary Circadian clocks were, until recently, seen as a consequence of rhythmic transcription of clock components, directed by transcriptional/translational feedback loops (TTFLs). Oscillations of protein modification were then discovered in cyanobacteria [1, 2]. Canonical posttranslational signaling processes have known importance for clocks across taxa [3–11]. More recently, evidence from the unicellular eukaryote Ostreococcus tauri revealed a transcription-independent, rhythmic protein modification [12] shared in anucleate human cells [13]. In this study, the Ostreococcus system reveals a central role for targeted protein degradation in the mechanism of circadian timing. The Ostreococcus clockwork contains a TTFL involving the morning-expressed CCA1 and evening-expressed TOC1 proteins [14]. Cellular CCA1 and TOC1 protein content and degradation rates are analyzed qualitatively and quantitatively using luciferase reporter fusion proteins. CCA1 protein degradation rates, measured in high time resolution, feature a sharp clock-regulated peak under constant conditions. TOC1 degradation peaks in response to darkness. Targeted protein degradation, unlike transcription and translation, is shown to be essential to sustain TTFL rhythmicity throughout the circadian cycle. Although proteasomal degradation is not necessary for sustained posttranslational oscillations in transcriptionally inactive cells, TTFL and posttranslational oscillators are normally coupled, and proteasome function is crucial to sustain both. PMID:21530263

van Ooijen, Gerben; Dixon, Laura E.; Troein, Carl; Millar, Andrew J.

2011-01-01

105

The function of neuromuscular system in maximal stretch-shortening cycle exercises: Comparison between power- and endurance-trained athletes  

Microsoft Academic Search

Differences in neuromuscular function between power athletes (n = 10) and endurance athletes (n = 10) were investigated in six different experimental conditions. In drop jumps and in stretch-shortening cycle (SSC) exercises on the sledge (sledge jumps), the subjects performed about 10 maximal jumps from the optimum dropping height (O) as well as from the dropping height of optimum ?40

Heikki Kyröläinen; Paavo V. Komi

1995-01-01

106

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

107

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.

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

2015-01-01

108

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

109

Stable isotope approaches for tracking C cycling and function in microbial communities  

NASA Astrophysics Data System (ADS)

Identifying the microorganisms responsible for specific processes in C cycling remains a major challenge in environmental microbiology, one that requires integration of multiple techniques. Stable isotope probing, or SIP, has come to represent a variety of powerful approaches that allow simultaneous identification of identity and function in microbial communities. Bulk methods such as DNA/RNA-SIP and PLFA-SIP are well developed and allow tracking of a multitude of C substrates (acetate, cellulose, CH4, CO2, and plant litter) into specific microbial consumers. However, to understand the spatio-temporal context of may key C transformations and microbial interactions, new imaging technologies are needed to analyze processes and properties of macromolecule complexes, microbes, plant root cells, soil (micro)aggregates, phytoplankton and marine snow as they undergoes formation and decomposition. New and sensitive in situ approaches include NanoSIMS single cell analysis, isotope arrays, and combinations of immuno- or FISH labeling with high resolution isotope imaging. Recent work illustrates how these powerful new techniques use targeted stable isotope probing to measure biological, physical and chemical processes and can be used in soil systems to study microbial mats or rhizosphere interactions. In both terrestrial and aquatic systems, they allow us to directly link C and other nutrient metabolism at the organismal level. Lastly, these new aproaches may be of great use in the study of trophic cascades and metabolic networks. While cross-feeding is often thought of as a confounding effect in SIP-type studies, with fine scale temporal sampling and FISH-SIMS analysis, we have the opportunity trace C flows through microbial foodwebs and to their eventual fate in stabilized organic-mineral complexes.

Pett-Ridge, J.

2008-12-01

110

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

111

LWR fuel-cycle costs as a function of burnup. Final report  

SciTech Connect

Utilities may be able to decrease fuel-cycle costs as much as 5% in PWRs and 6% in BWRs by increasing discharge burnup to optimum practical limits. With one exception, this analysis of 12- and 18-month fuel cycles indicated a potential for still further cost reductions at higher burnup rates than those considered (39 GWd/MtU for BWRs and 55 GWd/MtU for PWRs).

Franks, W.; Goldstein, L.; Joseph, L.; Nikmohammadian, N.

1984-11-01

112

Prediction of limit cycle pressure oscillations in gas turbine combustion systems using the flame describing function  

Microsoft Academic Search

Thermo-acoustic analysis is crucial for a successful development of new gas\\u000aturbine combustion systems. In this context, it becomes more and more\\u000anecessary to predict the limit cycle pressure amplitude of thermo-acoustic\\u000acombustion instabilities to figure out if they are within the critical design limit or will cause damage to the engine.\\u000aFor the prediction of limit cycle pressure amplitudes,

Harmen Jan Krediet

2012-01-01

113

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

114

Inactivation of the Tricarboxylic Acid Cycle Aconitase Gene from Streptomyces viridochromogenes Tü494 Impairs Morphological and Physiological Differentiation  

PubMed Central

The tricarboxylic acid (TCA) cycle aconitase gene acnA from Streptomyces viridochromogenes Tü494 was cloned and analyzed. AcnA catalyzes the isomerization of citrate to isocitrate in the TCA cycle, as indicated by the ability of acnA to complement the aconitase-deficient Escherichia coli mutant JRG3259. An acnA mutant was unable to develop aerial mycelium and to sporulate, resulting in a bald phenotype. Furthermore, the mutant did not produce the antibiotic phosphinothricin tripeptide, demonstrating that AcnA also affects physiological differentiation. PMID:10559181

Schwartz, D.; Kaspar, S.; Kienzlen, G.; Muschko, K.; Wohlleben, W.

1999-01-01

115

Genome-wide functional analysis of human cell-cycle regulators  

PubMed Central

Human cells have evolved complex signaling networks to coordinate the cell cycle. A detailed understanding of the global regulation of this fundamental process requires comprehensive identification of the genes and pathways involved in the various stages of cell-cycle progression. To this end, we report a genome-wide analysis of the human cell cycle, cell size, and proliferation by targeting >95% of the protein-coding genes in the human genome using small interfering RNAs (siRNAs). Analysis of >2 million images, acquired by quantitative fluorescence microscopy, showed that depletion of 1,152 genes strongly affected cell-cycle progression. These genes clustered into eight distinct phenotypic categories based on phase of arrest, nuclear area, and nuclear morphology. Phase-specific networks were built by interrogating knowledge-based and physical interaction databases with identified genes. Genome-wide analysis of cell-cycle regulators revealed a number of kinase, phosphatase, and proteolytic proteins and also suggests that processes thought to regulate G1-S phase progression like receptor-mediated signaling, nutrient status, and translation also play important roles in the regulation of G2/M phase transition. Moreover, 15 genes that are integral to TNF/NF-?B signaling were found to regulate G2/M, a previously unanticipated role for this pathway. These analyses provide systems-level insight into both known and novel genes as well as pathways that regulate cell-cycle progression, a number of which may provide new therapeutic approaches for the treatment of cancer. PMID:17001007

Mukherji, Mridul; Bell, Russell; Supekova, Lubica; Wang, Yan; Orth, Anthony P.; Batalov, Serge; Miraglia, Loren; Huesken, Dieter; Lange, Joerg; Martin, Christopher; Sahasrabudhe, Sudhir; Reinhardt, Mischa; Natt, Francois; Hall, Jonathan; Mickanin, Craig; Labow, Mark; Chanda, Sumit K.; Cho, Charles Y.; Schultz, Peter G.

2006-01-01

116

Functional requirement of AgRP and NPY neurons in ovarian cycle-dependent regulation of food intake  

PubMed Central

In female mammals including rodents and humans, feeding decreases during the periovulatory period of the ovarian cycle, which coincides with a surge in circulating estrogen levels. Ovariectomy increases food intake, which can be normalized by estrogen treatment at a dose and frequency mimicking those during the estrous cycle. Furthermore, administration of estrogen to rodents potently inhibits food intake. Despite these well-known effects of estrogen, neuronal subtypes that mediate estrogen's anorexigenic effects have not been identified. In this study, we show that changes in hypothalamic expression of agouti-related protein (Agrp) and neuropeptide Y (Npy) coincide with the cyclic changes in feeding across the estrous cycle. These cyclic changes in feeding are abolished in mice with degenerated AgRP neurons even though these mice cycle normally. Central administration of 17?-estradiol (E2) decreases food intake in controls but not in mice lacking the AgRP neurons. Furthermore, E2 treatment suppresses fasting-induced c-Fos activation in AgRP and NPY neurons and blunts the refeeding response. Surprisingly, although estrogen receptor alpha (ER?) is the key mediator of estrogen's anorexigenic effects, we find that expression of ER? is completely excluded from AgRP and NPY neurons in the mouse hypothalamus, suggesting that estrogen may regulate these neurons indirectly via presynaptic neurons that express ER?. This study indicates that neurons coexpressing AgRP and NPY are functionally required for the cyclic changes in feeding across estrous cycle and that AgRP and NPY neurons are essential mediators of estrogen's anorexigenic function. PMID:19805233

Olofsson, Louise E.; Pierce, Andrew A.; Xu, Allison W.

2009-01-01

117

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

118

Trichloroacetic acid cycling in Sitka spruce saplings and effects on sapling health following long term exposure  

E-print Network

Trichloroacetic acid cycling in Sitka spruce saplings and effects on sapling health following long Received 25 June 2003; accepted 18 December 2003 ``Capsule'': TCA stored in Sitka spruce needles may affect in conifers, 120 Sitka spruce (Picea sitchensis (Bong.) Carr) saplings were exposed to control, 10 or 100 mg l

Heal, Kate

119

Staphylococcus epidermidis Polysaccharide Intercellular Adhesin Production Significantly Increases during Tricarboxylic Acid Cycle Stress  

PubMed Central

Staphylococcal polysaccharide intercellular adhesin (PIA) is important for the development of a mature biofilm. PIA production is increased during growth in a nutrient-replete or iron-limited medium and under conditions of low oxygen availability. Additionally, stress-inducing stimuli such as heat, ethanol, and high concentrations of salt increase the production of PIA. These same environmental conditions are known to repress tricarboxylic acid (TCA) cycle activity, leading us to hypothesize that altering TCA cycle activity would affect PIA production. Culturing Staphylococcus epidermidis with a low concentration of the TCA cycle inhibitor fluorocitrate dramatically increased PIA production without impairing glucose catabolism, the growth rate, or the growth yields. These data lead us to speculate that one mechanism by which staphylococci perceive external environmental change is through alterations in TCA cycle activity leading to changes in the intracellular levels of biosynthetic intermediates, ATP, or the redox status of the cell. These changes in the metabolic status of the bacteria result in the attenuation or augmentation of PIA production. PMID:15838022

Vuong, Cuong; Kidder, Joshua B.; Jacobson, Erik R.; Otto, Michael; Proctor, Richard A.; Somerville, Greg A.

2005-01-01

120

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

E-print Network

measured. Total FES cycling power and work done increased with training. Lean muscle mass also increased significantly increased with training. Blood glucose and insulin levels were lower following the OGTT after 10 weeks of training. Triglyceride levels did not change following training. However, levels of IL-6, TNF

Griffin, Lisa

121

ADJUSTMENT TO FOOD DEPRIVATION CYCLES AS A FUNCTION OF AGE AND PRENATAL X IRRADIATION  

Microsoft Academic Search

Rats exposed to 100- to 200-r doses of x rays in utero between days 14 ; and 18 of gestation were placed on a 22-hr food deprivation cycle. Their ages at ; the start of the experiment varied from 75 to 735 days. Speed of adjustment to ; the food deprivation, measured in terms of the number of days that

R. S. Tacker; E. Furchtgott

1963-01-01

122

Changes in functional properties of mitochondria during growth cycle of Arabidopsis thaliana cell suspension cultures  

Microsoft Academic Search

Composition and properties of Percoll-purified mitochondria isolated from Arabidopsis thaliana cell suspension cultures were studied at various stages of the growth cycle. During the lag phase (2 days) mitochondria exhibited high lipid\\/ protein ratio, high double bound index and very low oxidative rate. After day 2 and up to day 4 for NADH (exponential phase), or to day 7 (beginning

Jacques Davy de Virville; Marie-Françoise Alin; Yvonne Aaron; René Rémy; Thérése Guillot-Salomon; Catherine Cantrel

1998-01-01

123

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

124

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

125

The mechanism of sensory transduction in a mechanoreceptor. Functional stages in campaniform sensilla during the molting cycle  

PubMed Central

This paper describes the ultrastructural modifications that cockroach campaniform sensilla undergo at three major stages in the molting cycle and finds that the sensilla are physiological functional at all developmental stages leading to ecdysis. Late stage animals on the verge of ecdysis have two completely separate cuticles. The campaniform sensillum sends a 220-mum extension of the sensory process through a hole in its cap in the new (inner) cuticle across a fluid-filled molting space to its functional insertion in the cap in the old (outer) cuticle. Mechanical stimulation of the old cap excites the sensillum. The ultrastructural geometry of late stage sensilla, coupled with the observation they are physiolgically functional, supports the hypotheses (a) that sensory transduction occurs at the tip of the sensory process, and (b) that cap identation causes the cap cuticle to pinch the tip of the sensory process, thereby stimulating the sensillum. PMID:993271

1976-01-01

126

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 ...

127

The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon  

Microsoft Academic Search

Megafaunal organisms play a key role in ecosystem functioning in the deep-sea through bioturbation, bioirrigation and organic matter cycling. At 3500 m water depth in the Nazaré Canyon, NE Atlantic, very high abundances of the infaunal holothurian Molpadia musculus were observed. To quantify the role of M. musculus in sediment cycling, sediment samples and holothurians were collected using an ROV

T. Amaro; S. Bianchelli; D. S. M. Billett; M. R. Cunha; A. Pusceddu; R. Danovaro

2010-01-01

128

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

129

C2 from Beet curly top virus meddles with the cell cycle: a novel function for an old pathogenicity factor.  

PubMed

Geminiviruses are ssDNA plant viruses that infect a wide range of crops. Since geminiviruses often infect terminally differentiated cells, they must induce cell cycle re-entry in order to replicate; until recently, only two viral proteins, the replication-associated protein Rep and the curtoviral pathogenicity factor C4, had been assigned a role in the restoration of cell competency. In a recent work, we demonstrated that C2 from Beet curly top virus activates the expression of host genes involved in DNA replication and/or control of the G2/M transition in a manner consistent with cell cycle re-entry. As expected, expression of BCTV C2 results in enhanced replication of DNA viruses. We conclude that BCTV C2 acts as a re-activator of the cell cycle in infected cells, enhancing the DNA replication competency and providing a cell environment favorable for replication of geminiviruses. Potential mechanisms for this novel function are discussed in light of our findings. PMID:23073019

Lozano-Duran, Rosa; Caracuel, Zaira; Bejarano, Eduardo R

2012-12-01

130

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

131

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

132

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

133

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

134

Extramitochondrial tricarboxylic acid cycle in retinal rod outer segments.  

PubMed

Vertebrate retinal rod Outer Segments (OS) are the site of visual transduction, an energy demanding process for which mechanisms of ATP supply are still poorly known. Glycolysis or diffusion of either ATP or phosphocreatine from the Inner Segment (IS) does not seem to display adequate timing to supply ATP for phototransduction. We have previously reported data suggesting an aerobic metabolism in OS, which would largely account for the light-stimulated ATP need of the photoreceptor. Here, by oxymetry and biochemical analyses we show that: (i) disks isolated by Ficoll flotation consume O(2) in the presence of physiological respiring substrates either in coupled or uncoupled conditions; (ii) OS homogenates contain the whole biochemical machinery for the degradation of glucose, i.e. glycolysis and the tricarboxylic acid cycle (TCA cycle), consistently with the results of our previous proteomic study. Activities of the 8 TCA cycle enzymes in OS were comparable to those in retinal mitochondria-enriched fractions. Disk and OS preparations were subjected to TEM analysis, and while they can be considered free of inner segment contaminants, immunogold with specific antibodies demonstrate the expression therein of both the visual pigment rhodopsin and F(o)F(1)-ATP synthase. Finally, double immunofluorescence on mouse retina sections demonstrated a colocalization of some respiratory complex mitochondrial proteins with rhodopsin in rod OS. Data, suggestive of the exportability of the mitochondrial machinery for aerobic metabolism, may shed light on those retinal pathologies related to energy supply impairment in OS and to mutations in TCA enzymes. PMID:21683117

Panfoli, Isabella; Calzia, Daniela; Ravera, Silvia; Bruschi, Maurizio; Tacchetti, Carlo; Candiani, Simona; Morelli, Alessandro; Candiano, Giovanni

2011-09-01

135

Elucidating Structure and Catalytic Cycles of Anti- or Ferro-magnetic Iron Enzymes from Spin Density Functional Theory  

NASA Astrophysics Data System (ADS)

Nature uses metal-containing enzymes to catalyze important biochemical reactions. Some enzymes, such as methane monooxygenase hydroxylase (MMOH), contain (anti)ferromagnetic binuclear iron centers that interact with dioxygen and/or other substrates to facilitate biochemical functions. We have studied the electronic and magnetic structures of several enzyme binuclear iron centers and predicted their spectroscopic properties. We have used spin density functional theory (SDFT) to predict ^57Fe M"ossbauer and other spectral parameters of MMOH and structurally related iron-containing enzymes. Upon dioxygen binding, the diiron center of MMOH undergoes a ferromagnetic to antiferromagnetic transition which may play an important role in its catalytic activity. In addition, based on our ability to predict spectroscopic data, we have been able to predict the structure of a key reaction intermediate in the MMOH catalytic cycle for which there is no X-ray structure.

Rodriguez, Jorge H.

2012-02-01

136

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

137

Amino-functionalized nanoparticles as inhibitors of mTOR and inducers of cell cycle arrest in leukemia cells.  

PubMed

Activation of the mammalian target of rapamycin (mTOR) has been implicated in anticancer drug resistance, type 2 diabetes, and aging. Here, we show that surface functionalization of polystyrene nanoparticles with amino groups (PS-NH2), but not with carboxyl groups (PS-COOH), induces G2 cell-cycle arrest and inhibition of proliferation in three leukemia cell lines. Besides, PS-NH2 inhibit angiogenesis and proliferation of leukemia cells xenografted onto the chick chorioallantoic membrane. At the molecular level, PS-NH2 inhibit, whereas PS-COOH activate mTOR signaling in leukemia cells. Consistently, PS-NH2 block activation of the mTOR downstream targets, Akt and p70 ribosomal S6 kinase 1, and induce overexpression of the cell-cycle regulator p21(Cip1/Waf1) and degradation of cyclin B1. After addition, both types of particles rapidly induce autophagy in leukemia cells. Yet, only in PS-NH2-treated cells, acidic vesicular organelles show elevated pH and impaired processing of procathepsin B. Moreover, solely in PS-NH2-treated cells, autophagy is followed by permeabilization of acidic vesicular organelles and induction of apoptosis. By contrast, primary macrophages, which do not exhibit activated mTOR signaling, proved relatively resistant to PS-NH2-induced toxicity. These data indicate that functionalized nanoparticles can be used to control activation of mTOR signaling pathways, and to influence proliferation and viability of malignant cells. PMID:24331713

Loos, Cornelia; Syrovets, Tatiana; Musyanovych, Anna; Mailänder, Volker; Landfester, Katharina; Simmet, Thomas

2014-02-01

138

Dual Functions of ?-Ketoglutarate Dehydrogenase E2 in the Krebs Cycle and Mitochondrial DNA Inheritance in Trypanosoma brucei  

PubMed Central

The dihydrolipoyl succinyltransferase (E2) of the multisubunit ?-ketoglutarate dehydrogenase complex (?-KD) is an essential Krebs cycle enzyme commonly found in the matrices of mitochondria. African trypanosomes developmentally regulate mitochondrial carbohydrate metabolism and lack a functional Krebs cycle in the bloodstream of mammals. We found that despite the absence of a functional ?-KD, bloodstream form (BF) trypanosomes express ?-KDE2, which localized to the mitochondrial matrix and inner membrane. Furthermore, ?-KDE2 fractionated with the mitochondrial genome, the kinetoplast DNA (kDNA), in a complex with the flagellum. A role for ?-KDE2 in kDNA maintenance was revealed in ?-KDE2 RNA interference (RNAi) knockdowns. Following RNAi induction, bloodstream trypanosomes showed pronounced growth reduction and often failed to equally distribute kDNA to daughter cells, resulting in accumulation of cells devoid of kDNA (dyskinetoplastic) or containing two kinetoplasts. Dyskinetoplastic trypanosomes lacked mitochondrial membrane potential and contained mitochondria of substantially reduced volume. These results indicate that ?-KDE2 is bifunctional, both as a metabolic enzyme and as a mitochondrial inheritance factor necessary for the distribution of kDNA networks to daughter cells at cytokinesis. PMID:23125353

Sykes, Steven E.

2013-01-01

139

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

140

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

141

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

142

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

143

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

144

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

145

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

146

The role of biodiversity for the carbon cycle: Implementation of functional diversity in a dynamic vegetation model  

NASA Astrophysics Data System (ADS)

Most dynamic global vegetation models (DGVMs) condense natural plant diversity to plant functional types (PFTs). A single PFT usually represents a whole biome, e.g. the PFT "tropical broadleaved evergreen tree" and its constant set of functional trait parameters covers entire regions in the model. This approach minimizes functional diversity and neglects the effects of functional diversity on the modeled vegetation and carbon dynamics. Our work aims to overcome this limitation and extend functional diversity in the vegetation model LPJmL to explore the role of biodiversity in climate change mitigation. Our approach improves the representation of biodiversity in the model by incorporating the natural ranges and eco-physiological interrelations of relevant plant traits. Empirical data on plant traits is provided by the TRY data base (www.try-db.org) and the ROBIN project (www.robinproject.info). A first sensitivity analysis revealed that simulated carbon stocks are very stable under a large range of trait combinations. However, several model output variables appeared highly sensitive to small changes of plant trait parameters and thus the introduction of trait ranges requires several improvements of the PFT concept of LPJmL. One possible way of improvement is to implement missing plant-trait tradeoffs, which will be used to simulate the growth of individual plants with flexible parameter combinations at the landscape scale. Our improved model will enable for the simulation of local competition and complementarity of individual plants which, according to their trait values and ranges, can then be categorized into a much broader variety of PFTs. This modeling approach will allow for investigating the role of bio- and functional diversity in the global carbon cycle as well as in regional vegetation dynamics.

Sakschewski, Boris; Boit, Alice; von Bloh, Werner; Rammig, Anja; Thonicke, Kirsten

2013-04-01

147

Elevated atmospheric CO2 impacts abundance and diversity of nitrogen cycling functional genes in soil.  

PubMed

The concentration of CO(2) in the Earth's atmosphere has increased over the last century. Although this increase is unlikely to have direct effects on soil microbial communities, increased atmospheric CO(2) may impact soil ecosystems indirectly through plant responses. This study tested the hypothesis that exposure of plants to elevated CO(2) would impact soil microorganisms responsible for key nitrogen cycling processes, specifically denitrification and nitrification. We grew trembling aspen (Populus tremuloides) trees in outdoor chambers under ambient (360 ppm) or elevated (720 ppm) levels of CO(2) for 5 years and analyzed the microbial communities in the soils below the trees using quantitative polymerase chain reaction and clone library sequencing targeting the nitrite reductase (nirK) and ammonia monooxygenase (amoA) genes. We observed a more than twofold increase in copy numbers of nirK and a decrease in nirK diversity with CO(2) enrichment, with an increased predominance of Bradyrhizobia-like nirK sequences. We suggest that this dramatic increase in nirK-containing bacteria may have contributed to the significant loss of soil N in the CO(2)-treated chambers. Elevated CO(2) also resulted in a significant decrease in copy numbers of bacterial amoA, but no change in archaeal amoA copy numbers. The decrease in abundance of bacterial amoA was likely a result of the loss of soil N in the CO(2)-treated chambers, while the lack of response for archaeal amoA supports the hypothesis that physiological differences in these two groups of ammonia oxidizers may enable them to occupy distinct ecological niches and respond differently to environmental change. PMID:22961365

Kelly, John J; Peterson, Emily; Winkelman, Jonathan; Walter, Teagan J; Rier, Steven T; Tuchman, Nancy C

2013-02-01

148

Secreted frizzled-related protein 2 is epigenetically silenced and functions as a tumor suppressor in oral squamous cell carcinoma  

PubMed Central

The role of epigenetic inactivation of secreted frizzled-related protein 2 (SFRP2) and its functions in the development of oral squamous cell carcinoma (OSCC) remain to be elucidated. The present study demonstrated that SFRP2 mRNA was detected in 97.96% of tumor-adjacent normal tissues, while its expression was only detected in 16.33% of the tumor samples. In addition, the loss of SFRP2 expression was associated with hypermethylation of its promoter. As expected, the overexpression of SFRP2 in OSCC cell lines (Tca8113) suppressed cell proliferation and arrested the cell cycle in the G1 phase. Overexpression of SFRP2 also effectively repressed tumor growth in xenograft animals. Mechanistic investigations revealed that SFRP2 inhibited the development of OSCC in vitro and in vivo through an increase in the expression levels of glycogen synthase kinase-3? and a decrease in the expression level of cyclin D1, a direct read-out gene of active Wnt signaling. In addition, an increase in the expression of ?-catenin was observed in the Tca8113/SFRP2 cells and in the animal models overexpressing SFRP2. Therefore, the results of the present study provide insight into the role of SFRP2 as a functional tumor suppressor in the development of OSCC through inhibition of the Wnt signaling pathway. Further studies on the precise mechanisms underlying the inhibition of Wnt signaling by SFRP2 and its association with ?-catenin are required. PMID:25189527

XIAO, CAN; WANG, LILI; ZHU, LIFANG; ZHANG, CHENPING; ZHOU, JIANHUA

2014-01-01

149

A functional and morphological approach to evaluate the vertical migration of estuarine intertidal nematodes during a tidal cycle  

NASA Astrophysics Data System (ADS)

We tested herein the hypothesis that exposure time significantly contributes to the vertical distribution profile of nematodes during a tidal cycle as a function of distinct feeding and locomotion behaviors, conditioned by body morphology. We showed that the vertical distribution profile of the slender with filiform tail, numerically dominant Terschellingia longicaudata is in fact significantly correlated with sediment changes induced by tidal variation. Conversely, none of the other nematode species showed unequivocal evidence of vertical migration. Horizontal spatial heterogeneity also influenced the vertical distribution of nematode associations, probably as a response to varying temperature and desiccation levels at the sediment surface. The resulting vertical profiles for individual or species groups are a trade-off among locomotory and feeding strategies and concordant morphological adaptations.

Brustolin, M. C.; Thomas, M. C.; Lana, P. C.

2013-03-01

150

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

151

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

152

The Functional Organization and Control of Plant Respiration  

Microsoft Academic Search

The respiratory pathways of glycolysis, the tricarboxylic acid (TCA) cycle, and mitochondrial electron transport chain (miETC) are central features of carbon metabolism and bioenergetics in aerobic organisms. Respiration is essential for growth, maintenance, and carbon balance of all plant cells. Although the majority of respiratory enzymes are common to all organisms, plant respiration has evolved as a complex metabolic network

William C. Plaxton; Florencio E. Podestá

2006-01-01

153

A Functional Analysis of the Influence of ?3-adrenoceptors on the Rat Micturition Cycle  

PubMed Central

Dysfunctions of the lower urinary tract, such as overactive bladder syndrome and incontinence, are the product of storage failure. Spontaneous regional bladder wall movements [nonmicturition contractions (NMCs)] are proposed to generate afferent activity that signals volume status to the central nervous system. The sympathetic nervous system, via activation of ?-adrenoceptors (?-ARs), causes bladder relaxation and promotes urine storage. We hypothesized that ?-AR regulation of micturition is mediated by suppression of NMCs. We used an unanesthetized, decerebrate, artificially perfused rat preparation that allows simultaneous cystometry with external urethral sphincter and pelvic afferent nerve recordings. Systemic isoprenaline (10 nM to 1 µM) increased intervoid interval and bladder compliance accompanied by a decrease in NMC amplitude, voiding pressure, and voiding threshold. Isoprenaline also reduced arterial pressure and increased heart rate. The ?3-AR agonist mirabegron (10–100 nM) increased intervoid interval and bladder compliance and reduced NMC amplitude, yet preserved active voiding function and had no effect on arterial pressure or heart rate. All of these effects of mirabegron were blocked by the selective ?3-AR antagonist N-[[3-[(2S)-2-hydroxy-3-[[2-[4-[(phenylsulfonyl)amino] phenyl]ethyl]amino]propoxy]phenyl]methyl]-acetamide (L748,337), which alone shortened intervoid interval and decreased bladder compliance—suggesting the presence of a basal ?3-AR–mediated sympathetic tone. Similar effects of mirabegron were seen in an acetic acid–sensitized bladder preparation and in preparations after loss of spinobulbar reflex bladder control. The ?3-AR–mediated increase in intervoid interval correlated with increased bladder compliance but not with the decrease in NMC amplitude. These findings indicate that ?3-adrenoceptors have a selective effect that improves urine storage by increasing compliance without affecting the active components of voiding. PMID:24008334

Sadananda, Prajni; Drake, Marcus J.; Paton, Julian F. R.

2013-01-01

154

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

NASA Astrophysics Data System (ADS)

Carbonates are the largest reservoirs of carbon on Earth. From mid-Mesozoic time, the biologically catalyzed precipitation of calcium carbonates by pelagic phytoplankton has been primarily due to the production of calcite by coccolithophorids. In this paper we address the physical and chemical processes that select for coccolithophorid blooms detected in Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color imagery. Our primary goal is to develop both diagnostic and prognostic models that represent the spatial and temporal dynamics of coccolithophorid blooms in order to improve our knowledge of the role of these organisms in mediating fluxes of carbon between the ocean, the atmosphere, and the lithosphere. On the basis of monthly composite images of classified coccolithophorid blooms and global climatological maps of physical variables and nutrient fields, we developed a probability density function that accounts for the physical chemical variables that predict the spatiotemporal distribution of coccolithophorids in the world oceans. Our analysis revealed that areas with sea surface temperatures (SST) between 3° and 15°C, a critical irradiance between 25 and 150 ?mol quanta m-2 s-1, and decreasing nitrate concentrations (?N/?t < 0) are selective for upper ocean large-scale coccolithophorid blooms. While these conditions favor both Northern and Southern Hemisphere blooms of the most abundant coccolithophorid in the modern oceans, Emiliania huxleyi, the Northern and Southern Hemisphere populations of this organism are genetically distinct. Applying amplified fragment length polymorphism as a marker of genetic diversity, we identified two major taxonomic clades of E. huxleyi; one is associated with the Northern Hemisphere blooms, while the other is found in the Southern Hemisphere. We suggest a rule of "universal distribution and local selection": that is, coccolithophorids can be considered cosmopolitan taxa, but their genetic plasticity provides physiological accommodation to local environmental selection pressure. Sea surface temperature, critical irradiance, and ?N/?t were predicted for the years 2060-2070 using the NCAR Community Climate System Model to generate future monthly probability distributions of coccolithophorids based upon the relationships observed between the environmental variables and coccolithophorid blooms in modern oceans. Our projected probability distribution analysis suggests that in the North Atlantic, the largest habitat for coccolithophorids on Earth, the areal extent of blooms will decrease by up to 50% by the middle of this century. We discuss how the magnitude of carbon fluxes may be affected by the evolutionary success of coccolithophorids in future climate scenarios.

Iglesias-RodríGuez, M. DéBora; Brown, Christopher W.; Doney, Scott C.; Kleypas, Joan; Kolber, Dorota; Kolber, Zbigniew; Hayes, Paul K.; Falkowski, Paul G.

2002-12-01

155

The effects of season and moderate nutritional restriction on ovarian function and oocyte nuclear maturation in cycling gilts.  

PubMed

The fertility of female pigs is impaired during summer and in response to restriction of feed intake, resulting in reduced productivity of the breeding herd. This study determined the effect of season and moderate nutritional restriction on ovarian function and oocyte developmental competence of cycling gilts. Eighty prepubescent gilts were used across two seasons-summer (S: January to March) and winter (W: June to August)-and received either a high (2.5× maintenance) or a moderately restricted (1.5× maintenance) feeding level for the first 19 days of their second estrous cycle. On Day 19, ovaries were collected post-slaughter. Diameters of all surface follicles over 1 mm were measured. All follicles ?4 mm were aspirated and cumulus-oocyte complexes underwent in vitro maturation for ?44 hours to assess oocyte developmental competence on the basis of metaphase II (MII) attainment. Moderate dietary nutrition reduced daily liveweight gain but did not affect the ovarian follicle population or oocyte developmental competence. The number of large follicles (?6 mm) was lower during summer (S: 10.7 ± 1.74 vs. W: 15.5 ± 1.15, P < 0.05), as was the proportion of oocytes at the germinal vesicle stage of meiosis (S: 0.06 ± 0.02 vs. W: 0.08 ± 0.02, P < 0.05). However, the proportion of oocytes attaining MII was similar in summer and winter (S: 0.72 ± 0.04 and W: 0.69 ± 0.06, P > 0.05). Intrafollicular concentrations of luteinizing hormone were higher in summer (S: 43.05 ± 6.44 vs. W: 12.05 ± 5.12 ng/mL, P < 0.001), whereas estradiol was lower (S: 1.27 ± 0.36 vs. W: 27.52 ± 5.59 ng/mL, P < 0.001). In conclusion, our data demonstrated that in summer, follicle growth beyond 6 mm is impaired during the periovulatory period, without affecting oocyte meiotic competence. Importantly, these data also demonstrated that ovarian follicle growth and the capacity of oocytes to reach MII in vitro appear unaffected by moderate nutritional restriction during the preceding estrous cycle. PMID:25263484

Swinbourne, A M; Kelly, J M; Kind, K L; Kennaway, D J; van Wettere, W H E J

2014-12-01

156

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

157

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

158

Cognitive functions of regularly cycling women may differ throughout the month, depending on sex hormone status; a possible explanation to conflicting results of studies of ADHD in females  

PubMed Central

Attention Deficit/Hyperactivity Disorder (ADHD) is considered as a model of neuro-developmental cognitive function. ADHD research previously studied mainly males. A major biological distinction between the genders is the presence of a menstrual cycle, which is associated with variations in sex steroid hormone levels. There is a growing body of literature showing that sex hormones have the ability to regulate intracellular signaling systems that are thought to be abnormal in ADHD. Thus, it is conceivable to believe that this functional interaction between sex hormones and molecules involved with synaptic plasticity and neurotransmitter systems may be associated with some of the clinical characteristics of women with ADHD. In spite of the impact of sex hormones on major neurotransmitter systems of the brain in a variety of clinical settings, the menstrual cycle is usually entered to statistical analyses as a nuisance or controlled for by only testing male samples. Evaluation of brain structure, function and chemistry over the course of the menstrual cycle as well as across the lifespan of women (premenarche, puberty, cycling period, premenopause, postmenopause) is critical to understanding sex differences in both normal and aberrant mental function and behavior. The studies of ADHD in females suggest confusing and non-consistent conclusions. None of these studies examined the possible relationship between phase of the menstrual cycle, sex hormones levels and ADHD symptoms. The menstrual cycle should therefore be taken into consideration in future studies in the neurocognitive field since it offers a unique opportunity to understand whether and how subtle fluctuations of sex hormones and specific combinations of sex hormones influence neuronal circuits implicated in the cognitive regulation of emotional processing. The investigation of biological models involving the role of estrogen, progesterone, and other sex steroids has the potential to generate new and improved diagnostic and treatment strategies that could change the course of cognitive-behavioral disorders such as ADHD. PMID:24744721

Haimov-Kochman, Ronit; Berger, Itai

2014-01-01

159

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

160

Solar Wind Helium Abundance as a Function of Speed and Heliographic Latitude: Variation through a Solar Cycle  

NASA Technical Reports Server (NTRS)

We present a study of the variation of the relative abundance of helium to hydrogen in the solar wind as a function of solar wind speed and heliographic latitude over the previous solar cycle. The average values of A(sub He), the ratio of helium to hydrogen number densities, are calculated in 25 speed intervals over 27-day Carrington rotations using Faraday Cup observations from the Wind spacecraft between 1995 and 2005. The higher speed and time resolution of this study compared to an earlier work with the Wind observations has led to the discovery of three new aspects of A(sub He), modulation during solar minimum from mid-1995 to mid-1997. First, we find that for solar wind speeds between 350 and 415 km/s, A(sub He), varies with a clear six-month periodicity, with a minimum value at the heliographic equatorial plane and a typical gradient of 0.01 per degree in latitude. For the slow wind this is a 30% effect. We suggest that the latitudinal gradient may be due to an additional dependence of coronal proton flux on coronal field strength or the stability of coronal loops. Second, once the gradient is subtracted, we find that A(sub He), is a remarkably linear function of solar wind speed. Finally, we identify a vanishing speed, at which A(sub He), is zero, is 259 km/s and note that this speed corresponds to the minimum solar wind speed observed at one AU. The vanishing speed may be related to previous theoretical work in which enhancements of coronal helium lead to stagnation of the escaping proton flux. During solar maximum the A(sub He), dependences on speed and latitude disappear, and we interpret this as evidence of two source regions for slow solar wind in the ecliptic plane, one being the solar minimum streamer belt and the other likely being active regions.

Kasper, J. C.; Stenens, M. L.; Stevens, M. L.; Lazarus, A. J.; Steinberg, J. T.; Ogilvie, Keith W.

2006-01-01

161

Elementary flux modes analysis of functional domain networks allows a better metabolic pathway interpretation.  

PubMed

Metabolic network analysis is an important step for the functional understanding of biological systems. In these networks, enzymes are made of one or more functional domains often involved in different catalytic activities. Elementary flux mode (EFM) analysis is a method of choice for the topological studies of these enzymatic networks. In this article, we propose to use an EFM approach on networks that encompass available knowledge on structure-function. We introduce a new method that allows to represent the metabolic networks as functional domain networks and provides an application of the algorithm for computing elementary flux modes to analyse them. Any EFM that can be represented using the classical representation can be represented using our functional domain network representation but the fine-grained feature of functional domain networks allows to highlight new connections in EFMs. This methodology is applied to the tricarboxylic acid cycle (TCA cycle) of Bacillus subtilis, and compared to the classical analyses. This new method of analysis of the functional domain network reveals that a specific inhibition on the second domain of the lipoamide dehydrogenase (pdhD) component of pyruvate dehydrogenase complex leads to the loss of all fluxes. Such conclusion was not predictable in the classical approach. PMID:24204596

Pérès, Sabine; Felicori, Liza; Molina, Franck

2013-01-01

162

Effect of multiple mutations in tricarboxylic acid cycle and one-carbon metabolism pathways on Edwardsiella ictaluri pathogenesis.  

PubMed

Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia of catfish (ESC). We have shown recently that tricarboxylic acid cycle (TCA) and one-carbon (C1) metabolism are involved in E. ictaluri pathogenesis. However, the effect of multiple mutations in these pathways is unknown. Here, we report four novel E. ictaluri mutants carrying double gene mutations in TCA cycle (Ei?mdh?sdhC, Ei?frdA?sdhC), C1 metabolism (Ei?glyA?gcvP), and both TCA and C1 metabolism pathways (Ei?gcvP?sdhC). In-frame gene deletions were constructed by allelic exchange and mutants' virulence and vaccine efficacy were evaluated using in vivo bioluminescence imaging (BLI) as well as end point mortality counts in catfish fingerlings. Results indicated that all the double gene mutants were attenuated compared to wild-type (wt) E. ictaluri. There was a 1.39-fold average reduction in bioluminescence, and hence bacterial numbers, from all the mutants except for Ei?frdA?sdhC at 144 h post-infection. Vaccination with mutants was very effective in protecting channel catfish against subsequent infection with virulent E. ictaluri 93-146 strain. In particular, immersion vaccination resulted in complete protection. Our results provide further evidence on the importance of TCA and C1 metabolism pathways in bacterial pathogenesis. PMID:24418045

Dahal, N; Abdelhamed, H; Lu, J; Karsi, A; Lawrence, M L

2014-02-21

163

Development of a whole community genome amplification-assisted DNA microarray method to detect functional genes involved in the nitrogen cycle.  

PubMed

A novel DNA microarray analysis targeting key functional genes involved in most nitrogen cycling reactions was developed to comprehensively analyze microbial populations associated with the nitrogen cycle. The developed microarray contained 876 oligonucleotide probes based on the nucleotide sequences of the nif, amo, hao/hzo, nap, nar, nirK, nirS, nrf, cnor, qnor and nos genes. An analytical method combining detection by the designed microarray with whole community genome amplification was then applied to monitor the nitrogen cycling microorganisms in river water and wastewater treatment sludge samples. The developed method revealed that nitrogen cycling microorganisms in river water appeared to become less diverse in response to input of effluent from municipal wastewater treatment plants. Additionally, the nitrogen cycling community associated with anaerobic ammonium oxidation and partial nitrification reactors could be reasonably analyzed by the developed method. However, the results obtained for two activated sludge samples from municipal wastewater treatment plants with almost equivalent wastewater treatment performance differed greatly from each other. These results suggested that the developed method is useful for comprehensive analysis of nitrogen cycling microorganisms, although its applicability to complex samples with abundant untargeted populations should be further examined. PMID:25103865

Inoue, Daisuke; Pang, Junqin; Matsuda, Masami; Sei, Kazunari; Nishida, Kei; Ike, Michihiko

2014-11-01

164

Thermochemical cycles  

NASA Technical Reports Server (NTRS)

The thermochemical production of hydrogen is described along with the HYDRGN computer program which attempts to rate the various thermochemical cycles. Specific thermochemical cycles discussed include: iron sulfur cycle; iron chloride cycle; and hybrid sulfuric acid cycle.

Funk, J. E.; Soliman, M. A.; Carty, R. H.; Conger, W. L.; Cox, K. E.; Lawson, D.

1975-01-01

165

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

166

Triheptanoin partially restores levels of tricarboxylic acid cycle intermediates in the mouse pilocarpine model of epilepsy.  

PubMed

Triheptanoin, the triglyceride of heptanoate, is anticonvulsant in various epilepsy models. It is thought to improve energy metabolism in the epileptic brain by re-filling the tricarboxylic acid (TCA) cycle with C4-intermediates (anaplerosis). Here, we injected mice with [1,2-(13) C]glucose 3.5-4 weeks after pilocarpine-induced status epilepticus (SE) fed either a control or triheptanoin diet. Amounts of metabolites and incorporations of (13) C were determined in extracts of cerebral cortices and hippocampal formation and enzyme activity and mRNA expression were quantified. The percentage enrichment with two (13) C atoms in malate, citrate, succinate, and GABA was reduced in hippocampal formation of control-fed SE compared with control mice. Except for succinate, these reductions were not found in triheptanoin-fed SE mice, indicating that triheptanoin prevented a decrease of TCA cycle capacity. Compared to those on control diet, triheptanoin-fed SE mice showed few changes in most other metabolite levels and their (13) C labeling. Reduced pyruvate carboxylase mRNA and enzyme activity in forebrains and decreased [2,3-(13) C]aspartate amounts in cortex suggest a pyruvate carboxylation independent source of C-4 TCA cycle intermediates. Most likely anaplerosis was kept unchanged by carboxylation of propionyl-CoA derived from heptanoate. Further studies are proposed to fully understand triheptanoin's effects on neuroglial metabolism and interaction. PMID:24236946

Hadera, Mussie G; Smeland, Olav B; McDonald, Tanya S; Tan, Kah Ni; Sonnewald, Ursula; Borges, Karin

2014-04-01

167

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

168

Effect of glycerol-induced hyperhydration on thermoregulatory and cardiovascular functions and endurance performance during prolonged cycling in a 25°C environment  

Microsoft Academic Search

We compared the effect of glycerol-induced hyperhydration (GIH) to that of water-induced hyperhydration (WIH) on cardiovascular and thermoregulatory functions and endurance performance (EP) during prolonged cycling in a temperate climate in subjects consuming fluid during exercise. At weekly intervals, 6 trained male subjects ingested, in a randomized, double-blind, counterbalanced fashion, either a glycerol (1.2 g glycerol\\/kg bodyweight (BW) with 26

Eric D. B. Goulet; Robert A. Robergs; Susan Labrecque; Donald Royer; Isabelle J. Dionne

2006-01-01

169

Pre-B cell receptor-mediated cell cycle arrest in Philadelphia chromosome-positive acute lymphoblastic leukemia requires IKAROS function.  

PubMed

B cell lineage acute lymphoblastic leukemia (ALL) arises in virtually all cases from B cell precursors that are arrested at pre-B cell receptor-dependent stages. The Philadelphia chromosome-positive (Ph(+)) subtype of ALL accounts for 25-30% of cases of adult ALL, has the most unfavorable clinical outcome among all ALL subtypes and is defined by the oncogenic BCR-ABL1 kinase and deletions of the IKAROS gene in >80% of cases. Here, we demonstrate that the pre-B cell receptor functions as a tumor suppressor upstream of IKAROS through induction of cell cycle arrest in Ph(+) ALL cells. Pre-B cell receptor-mediated cell cycle arrest in Ph(+) ALL cells critically depends on IKAROS function, and is reversed by coexpression of the dominant-negative IKAROS splice variant IK6. IKAROS also promotes tumor suppression through cooperation with downstream molecules of the pre-B cell receptor signaling pathway, even if expression of the pre-B cell receptor itself is compromised. In this case, IKAROS redirects oncogenic BCR-ABL1 tyrosine kinase signaling from SRC kinase-activation to SLP65, which functions as a critical tumor suppressor downstream of the pre-B cell receptor. These findings provide a rationale for the surprisingly high frequency of IKAROS deletions in Ph(+) ALL and identify IKAROS-mediated cell cycle exit as the endpoint of an emerging pathway of pre-B cell receptor-mediated tumor suppression. PMID:19620627

Trageser, Daniel; Iacobucci, Ilaria; Nahar, Rahul; Duy, Cihangir; von Levetzow, Gregor; Klemm, Lars; Park, Eugene; Schuh, Wolfgang; Gruber, Tanja; Herzog, Sebastian; Kim, Yong-mi; Hofmann, Wolf-Karsten; Li, Aihong; Storlazzi, Clelia Tiziana; Jäck, Hans-Martin; Groffen, John; Martinelli, Giovanni; Heisterkamp, Nora; Jumaa, Hassan; Müschen, Markus

2009-08-01

170

Gene expression profiling of bovine endometrium during the oestrous cycle: detection of molecular pathways involved in functional changes  

Microsoft Academic Search

The endometrium plays a central role among the reproductive tissues in the context of early embryo-maternal communication and pregnancy. It undergoes typical changes during the sexual\\/oestrous cycle, which are regulated by the ovarian hormones progesterone and oestrogen. To identify the underlying molecular mechanisms we have performed the first holistic screen of transcriptome changes in bovine intercaruncular endometrium at two stages

S Bauersachs; S E Ulbrich; K Gross; SEM Schmidt; HHD Meyer; R Einspanier; H Wenigerkind; M Vermehren; H Blum; F Sinowatz; E Wolf

2005-01-01

171

Responses of Antarctic soil microbial communities and associated functions to temperature and freeze-thaw cycle frequency  

Microsoft Academic Search

Climatic changes will not only result in higher overall temperature, but also in greater variability in weather conditions. Antarctic soils are subjected to extremely variable conditions in the form of frequent freeze–thaw cycles (FTCs), but the importance of alteration in FTC frequency, compared with increases in average temperature and indirect vegetation-mediated effects on soil microorganisms, is still unknown. We therefore

Etienne Yergeau; George A. Kowalchuk

2008-01-01

172

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

173

The influence of temperature on the evolution of functional properties during pseudoelastic cycling of ultra fine grained NiTi  

Microsoft Academic Search

In the present study we used uniaxial pull-pull fatigue loading to study the pseudoelastic properties of ultra fine grained (grain size: 50–100nm) NiTi wires. The pseudoelastic behavior of shape memory alloys is not an ideal process. We show how pull-pull cycling changes the pseudoelastic properties, resulting in a decrease of plateau stresses (characterizing the forward and reverse transformation) and an

J. Olbricht; A. Yawny; A. M. Condó; F. C. Lovey; G. Eggeler

2008-01-01

174

Follicular-fluid anti-Mullerian hormone (FF AMH) is a plausible biochemical indicator of functional viability of oocyte in conventional in vitro fertilization (IVF) cycles  

PubMed Central

CONTEXT: Oocyte quality may be a governing factor in influencing in vitro fertilization (IVF) outcomes. However, morphological evaluation of oocyte quality is difficult in conventional IVF cycles. Follicular-fluid (FF), the site for oocyte growth and development, has not yet been sufficiently explored to obtain a marker indicative of oocyte quality. Anti-Mullerian hormone (AMH) is produced by granulosa cells of preantral and early-antral follicles and is released in FF. AIM: To investigate AMH as a biochemical indicator of functional viability/quality of oocyte produced in the FF micro-environmental milieu. SETTINGS AND DESIGN: Prospective study involving 132 cycles of conventional IVF-embryo transfer (ET) in infertile women. SUBJECTS AND METHODS: AMH concentration was estimated in pooled FF on day of oocyte pickup. Cycles were sorted into low and high groups according to median (50 th centile) values of measurement. Main outcome measure was oocyte viability, which included morphological assessment of oocyte quality, fertilization rate, clinical pregnancy, and implantation rates. STATISTICAL ANALYSIS: Graph-pad Prism 5 statistical package. RESULTS: Low FF AMH group shows significantly higher percentage of top-quality oocytes (65.08 ± 24.88 vs. 50.18 ± 25.01%, P =0.0126), fertilization (83.65 ± 18.38 vs. 75.78 ± 21.02%, P =0.0171), clinical pregnancy (57.57 vs. 16.67%, P >0.0001), and embryo implantation rates (29.79 vs. 7.69%, P >0.0001) compared to high FF AMH group. FF AMH shares an inverse correlation with FF E2 (Pearson r = ?0.43, r2 = 0.18) and clinical pregnancy (Pearson r = ?0.46, r2 = 0.21). Threshold value of FF AMH for pregnancy is >1.750 ng/mg protein. CONCLUSION: FF AMH is a plausible biochemical indicator of functional viability of oocyte in conventional IVF cycles. PMID:24082650

Mehta, Bindu N; Chimote, Meena N; Chimote, Nishad N; Nath, Nirmalendu M; Chimote, Natachandra M

2013-01-01

175

Sensory screening for large-format natural corks by "dry soak" testing and its correlation to headspace solid-phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) releasable trichloroanisole (TCA) analysis.  

PubMed

Large-format natural corks were individually screened for trichloroanisole (TCA) taint and other non-characteristic cork odors by smelling the high relative humidity headspace of the jarred closure during expert panel sensory sessions. The method was coined "dry soak sensory screening". Out of a population of 2296 corks, 138 specimens [6% of the total population (TP)] were retained because of unusual odors, ranging from mild to severe. All retained corks were analyzed for releasable TCA (RTCA) by the solid-phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) technique. Results indicated that 30 corks (1.3% TP) had concentrations between 1.0 and 5.0 ppt. Most of these corks had non-typical TCA odors described as ashtray, musty, moldy, dirty, and wet cardboard. A total of 13 retained corks (0.57% TP) had RTCA values higher than 5.0 ppt, mostly displaying the typical TCA odor. Dry soak screening has been determined to be a clean, fast, and most importantly, a nondestructive method ideal for screening large-format natural corks with off odors. PMID:19722710

Macku, Carlos; Gonzalez, Lesa; Schleussner, Christiane; Mesquita, Ana Cristina; Herwatt, James W; Kirch, Leonard C; Schwartz, Rob J

2009-09-01

176

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

177

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

178

Dynamics of Rad9 Chromatin Binding and Checkpoint Function Are Mediated by Its Dimerization and Are Cell Cycle–Regulated by CDK1 Activity  

PubMed Central

Saccharomyces cerevisiae Rad9 is required for an effective DNA damage response throughout the cell cycle. Assembly of Rad9 on chromatin after DNA damage is promoted by histone modifications that create docking sites for Rad9 recruitment, allowing checkpoint activation. Rad53 phosphorylation is also dependent upon BRCT-directed Rad9 oligomerization; however, the crosstalk between these molecular determinants and their functional significance are poorly understood. Here we report that, in the G1 and M phases of the cell cycle, both constitutive and DNA damage-dependent Rad9 chromatin association require its BRCT domains. In G1 cells, GST or FKBP dimerization motifs can substitute to the BRCT domains for Rad9 chromatin binding and checkpoint function. Conversely, forced Rad9 dimerization in M phase fails to promote its recruitment onto DNA, although it supports Rad9 checkpoint function. In fact, a parallel pathway, independent on histone modifications and governed by CDK1 activity, allows checkpoint activation in the absence of Rad9 chromatin binding. CDK1-dependent phosphorylation of Rad9 on Ser11 leads to specific interaction with Dpb11, allowing Rad53 activation and bypassing the requirement for the histone branch. PMID:20700441

Novarina, Daniele; Panigada, Davide; Puddu, Fabio; Abreu, Carla Manuela; Kumar, Ramesh; Grenon, Muriel; Lowndes, Noel F.; Plevani, Paolo; Muzi-Falconi, Marco

2010-01-01

179

Dynamics of Rad9 chromatin binding and checkpoint function are mediated by its dimerization and are cell cycle-regulated by CDK1 activity.  

PubMed

Saccharomyces cerevisiae Rad9 is required for an effective DNA damage response throughout the cell cycle. Assembly of Rad9 on chromatin after DNA damage is promoted by histone modifications that create docking sites for Rad9 recruitment, allowing checkpoint activation. Rad53 phosphorylation is also dependent upon BRCT-directed Rad9 oligomerization; however, the crosstalk between these molecular determinants and their functional significance are poorly understood. Here we report that, in the G1 and M phases of the cell cycle, both constitutive and DNA damage-dependent Rad9 chromatin association require its BRCT domains. In G1 cells, GST or FKBP dimerization motifs can substitute to the BRCT domains for Rad9 chromatin binding and checkpoint function. Conversely, forced Rad9 dimerization in M phase fails to promote its recruitment onto DNA, although it supports Rad9 checkpoint function. In fact, a parallel pathway, independent on histone modifications and governed by CDK1 activity, allows checkpoint activation in the absence of Rad9 chromatin binding. CDK1-dependent phosphorylation of Rad9 on Ser11 leads to specific interaction with Dpb11, allowing Rad53 activation and bypassing the requirement for the histone branch. PMID:20700441

Granata, Magda; Lazzaro, Federico; Novarina, Daniele; Panigada, Davide; Puddu, Fabio; Abreu, Carla Manuela; Kumar, Ramesh; Grenon, Muriel; Lowndes, Noel F; Plevani, Paolo; Muzi-Falconi, Marco

2010-08-01

180

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

181

ISG15 Functions as an Interferon-Mediated Antiviral Effector Early in the Murine Norovirus Life Cycle  

PubMed Central

ABSTRACT Human noroviruses (HuNoV) are the leading cause of nonbacterial gastroenteritis worldwide. Similar to HuNoV, murine noroviruses (MNV) are enteric pathogens spread via the fecal-oral route and have been isolated from numerous mouse facilities worldwide. Type I and type II interferons (IFN) restrict MNV-1 replication; however, the antiviral effectors impacting MNV-1 downstream of IFN signaling are largely unknown. Studies using dendritic cells, macrophages, and mice deficient in free and conjugated forms of interferon-stimulated gene 15 (ISG15) revealed that ISG15 conjugation contributes to protection against MNV-1 both in vitro and in vivo. ISG15 inhibited a step early in the viral life cycle upstream of viral genome transcription. Directly transfecting MNV-1 RNA into IFN-stimulated mouse embryonic fibroblasts (MEFs) and bone marrow-derived dendritic cells (BMDC) lacking ISG15 conjugates bypassed the antiviral activity of ISG15, further suggesting that ISG15 conjugates restrict the MNV-1 life cycle at the viral entry/uncoating step. These results identify ISG15 as the first type I IFN effector regulating MNV-1 infection both in vitro and in vivo and for the first time implicate the ISG15 pathway in the regulation of early stages of MNV-1 replication. IMPORTANCE Type I IFNs are important in controlling murine norovirus 1 (MNV-1) infections; however, the proteins induced by IFNs that restrict viral growth are largely unknown. This report reveals that interferon-stimulated gene 15 (ISG15) mitigates MNV-1 replication both in vitro and in vivo. In addition, it shows that ISG15 inhibits MNV-1 replication by targeting an early step in the viral life cycle, MNV-1 entry and/or uncoating. These results identify ISG15 as the first type I IFN effector regulating MNV-1 infection both in vitro and in vivo and for the first time implicate the ISG15 pathway in the regulation of viral entry/uncoating. PMID:24899198

Rodriguez, Marisela R.; Monte, Kristen; Thackray, Larissa B.

2014-01-01

182

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

183

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 sÃ?1 , AHe varies with a clear 6 month periodicity

Richardson, John

184

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...

185

The large tumor antigen: a "Swiss Army knife" protein possessing the functions required for the polyomavirus life cycle.  

PubMed

The SV40 large tumor antigen (L-Tag) is involved in the replication and cell transformation processes that take place during the polyomavirus life cycle. The ability of the L-Tag to interact with and to inactivate the tumor suppressor proteins p53 and pRb, makes this polyfunctional protein an interesting target in the search for compounds with antiviral and/or antiproliferative activities designed for the management of polyomavirus-associated diseases. The severe diseases caused by polyomaviruses, mainly in immunocompromised hosts, and the absence of licensed treatments, make the discovery of new antipolyomavirus drugs urgent. Parallels can be made between the SV40 L-Tag and the human papillomavirus (HPV) oncoproteins (E6 and E7) as they are also able to deregulate the cell cycle in order to promote cell transformation and its maintenance. In this review, a presentation of the SV40 L-Tag characteristics, regarding viral replication and cellular transformation, will show how similar these two processes are between the polyoma- and papillomavirus families. Insights at the molecular level will highlight similarities in the binding of polyoma- and papillomavirus replicative helicases to the viral DNA and in their disruptions of the p53 and pRb tumor suppressor proteins. PMID:23201316

Topalis, D; Andrei, G; Snoeck, R

2013-02-01

186

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

187

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

2014-10-01

188

Subcellular localization of glyoxylate cycle key enzymes involved in oxalate biosynthesis of wood-destroying basidiomycete Fomitopsis palustris grown on glucose.  

PubMed

This study investigated the subcellular localization of key enzymes of the glyoxylate cycle, i.e. isocitrate lyase (ICL; EC 4.1.3.1) and malate synthase (EC 2.3.3.9), that function constitutively in coordination with oxalate biosynthesis of glucose-grown Fomitopsis palustris. The ICL purified previously from F. palustris is termed FPICL1. Subcellular fractionation analysis of the cell homogenate by the sucrose density-gradient method showed that both key enzymes were present in peroxisomes, whereas acetyl-CoA synthase (EC 6.2.1.1) and oxalate-producing oxaloacetate acetylhydrolase (EC 3.7.1.1) were cytosolic. The peroxisomal localization of FPICL1 was further confirmed by electron microscopic and immunocytochemical analysis with anti-FPICL1 antibody. In addition, the peroxisomal target signal, composed of SKL at the C terminus of the cDNA encoding FPICL1, was found, which also suggests that FPICL1 is peroxisomal. Accordingly, it is postulated that transportation of succinate from peroxisomes to mitochondria, and vice versa, for the transportation of isocitrate or citrate, occurs in glucose-grown F. palustris for the constitutive metabolic coordination of the TCA and glyoxylate cycles with oxalate biosynthesis. PMID:16735748

Sakai, Shunsuke; Nishide, Tatsunori; Munir, Erman; Baba, Kei'ichi; Inui, Hiroshi; Nakano, Yoshihisa; Hattori, Takefumi; Shimada, Mikio

2006-06-01

189

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.

Integrated Teaching and Learning Program,

190

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

191

Diversity of sulfur-cycle prokaryotes in freshwater lake sediments investigated using aprA as the functional marker gene.  

PubMed

The diversity of sulfate-reducing prokaryotes (SRPs) and sulfur-oxidizing prokaryotes (SOPs) in freshwater lake ecosystems was investigated by cloning and sequencing of the aprA gene, which encodes for a key enzyme in dissimilatory sulfate reduction and sulfur oxidation. To understand their diversity better, the spatial distribution of aprA genes was investigated in sediments collected from six geographically distant lakes in Antarctica and Japan, including a hypersaline lake for comparison. The microbial community compositions of freshwater sediments and a hypersaline sediment showed notable differences. The clones affiliated with Desulfobacteraceae and Desulfobulbaceae were frequently detected in all freshwater lake sediments. The SOP community was mainly composed of four major phylogenetic groups. One of them formed a monophyletic cluster with a sulfur-oxidizing betaproteobacterium, Sulfuricella denitrificans, but the others were not assigned to specific genera. In addition, the AprA sequences, which were not clearly affiliated to either SRP or SOP lineages, dominated the libraries from four freshwater lake sediments. The results showed the wide distribution of some sulfur-cycle prokaryotes across geographical distances and supported the idea that metabolic flexibility is an important feature for SRP survival in low-sulfate environments. PMID:23810657

Watanabe, Tomohiro; Kojima, Hisaya; Takano, Yoshinori; Fukui, Manabu

2013-09-01

192

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

2014-11-01

193

Function and metabolic significance of penicillin, aureomycin and bacitracin in the life cycle of the domestic fowl  

E-print Network

& ~ a zth y' SAp portion of the intestinal floraz other types of microorganisms commonly found in the chicken's intestines by these workers were lactobacilliv micrococci, pseudomonads, bacilli, sarcinae, clostridia, and yeasts ~ Kern (1897) found 21... in rate of gowth is not yet clear. The effect of the antibiotics is thought to be an indirect one on thc intestinal f'lora of' the f'owl. Since an antibiotic will increase the rate of' growth it seemed worth- while to determine the function...

Elam, James Fletcher

1951-01-01

194

Estrogenic environmental endocrine-disrupting chemical effects on reproductive neuroendocrine function and dysfunction across the life cycle  

Microsoft Academic Search

Endocrine disrupting chemicals (EDCs) are natural or synthetic compounds that interfere with the normal function of an organism’s\\u000a endocrine system. Many EDCs are resistant to biodegradation, due to their structural stability, and persist in the environment.\\u000a The focus of this review is on natural and artificial EDCs that act through estrogenic mechanisms to affect reproductive neuroendocrine\\u000a systems. This endocrine axis

Sarah M. Dickerson; Andrea C. Gore

2007-01-01

195

CstF64: cell cycle regulation and functional role in 3' end processing of replication-dependent histone mRNAs.  

PubMed

The 3' end processing of animal replication-dependent histone mRNAs is activated during G1/S-phase transition. The processing site is recognized by stem-loop binding protein and the U7 snRNP, but cleavage additionally requires a heat-labile factor (HLF), composed of cleavage/polyadenylation specificity factor, symplekin, and cleavage stimulation factor 64 (CstF64). Although HLF has been shown to be cell cycle regulated, the mechanism of this regulation is unknown. Here we show that levels of CstF64 increase toward the S phase and its depletion affects histone RNA processing, S-phase progression, and cell proliferation. Moreover, analyses of the interactions between CstF64, symplekin, and the U7 snRNP-associated proteins FLASH and Lsm11 indicate that CstF64 is important for recruiting HLF to histone precursor mRNA (pre-mRNA)-resident proteins. Thus, CstF64 is central to the function of HLF and appears to be at least partly responsible for its cell cycle regulation. Additionally, we show that misprocessed histone transcripts generated upon CstF64 depletion mainly accumulate in the nucleus, where they are targets of the exosome machinery, while a small cytoplasmic fraction is partly associated with polysomes. PMID:25266659

Romeo, Valentina; Griesbach, Esther; Schümperli, Daniel

2014-12-01

196

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

197

The trophic biology of the holothurian Molpadia musculus: implications for organic matter cycling and ecosystem functioning in a deep submarine canyon  

NASA Astrophysics Data System (ADS)

Megafaunal organisms play a key role in ecosystem functioning in the deep-sea through bioturbation, bioirrigation and organic matter cycling. At 3500 m water depth in the Nazaré Canyon, NE Atlantic, very high abundances of the infaunal holothurian Molpadia musculus were observed. To quantify the role of M. musculus in sediment cycling, sediment samples and holothurians were collected using an ROV and in situ experiments were conducted with incubation chambers. The biochemical composition of the sediment (in terms of proteins, carbohydrates and lipids), the holothurians' gut contents and holothurians' faecal material were analysed. In the sediments, proteins were the dominant organic compound, followed by carbohydrates and lipids. In the holothurian's gut contents, protein concentrations were higher than the other compounds, decreasing significantly as the material passed through the digestive tract. Approximately 33±1% of the proteins were digested by the time sediment reached the mid gut, with a total digestion rate equal to 67±1%. Carbohydrates and lipids were ingested in smaller amounts and digested with lower efficiencies (23±11% and 50±11%, respectively). As a result, the biopolymeric C digestion rate was on average 62±3%. We estimated that the population of M. musculus could remove approximately 0.49±0.13 g biopolymeric C and 0.13±0.03 g N m-2 d-1 from the sediments. These results suggest that M. musculus plays a key role in the benthic tropho-dynamics and biogeochemical processes in the Nazaré Canyon.

Amaro, T.; Bianchelli, S.; Billett, D. S. M.; Cunha, M. R.; Pusceddu, A.; Danovaro, R.

2010-08-01

198

Rock Cycle  

NSDL National Science Digital Library

This interactive Flash animation about the rock cycle is suitable for a review or overview in an introductory level Physical Geology class. It includes animations, photos, and descriptions involving rock types and processes in the rock cycle.

Smoothstone; Company, Houghton M.

199

Rock Cycle  

NSDL National Science Digital Library

The purpose of this activity is to demonstrate the principle of conservation of mass through the rock cycle. When students create the model, the various parts and processes in the rock cycle are reinforced for them.

School, Maryland V.

200

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

201

SYN2 is an autism predisposing gene: loss-of-function mutations alter synaptic vesicle cycling and axon outgrowth  

PubMed Central

An increasing number of genes predisposing to autism spectrum disorders (ASDs) has been identified, many of which are implicated in synaptic function. This ‘synaptic autism pathway’ notably includes disruption of SYN1 that is associated with epilepsy, autism and abnormal behavior in both human and mice models. Synapsins constitute a multigene family of neuron-specific phosphoproteins (SYN1-3) present in the majority of synapses where they are implicated in the regulation of neurotransmitter release and synaptogenesis. Synapsins I and II, the major Syn isoforms in the adult brain, display partially overlapping functions and defects in both isoforms are associated with epilepsy and autistic-like behavior in mice. In this study, we show that nonsense (A94fs199X) and missense (Y236S and G464R) mutations in SYN2 are associated with ASD in humans. The phenotype is apparent in males. Female carriers of SYN2 mutations are unaffected, suggesting that SYN2 is another example of autosomal sex-limited expression in ASD. When expressed in SYN2 ?knockout neurons, wild-type human Syn II fully rescues the SYN2 knockout phenotype, whereas the nonsense mutant is not expressed and the missense mutants are virtually unable to modify the SYN2 knockout phenotype. These results identify for the first time SYN2 ?as a novel predisposing gene for ASD and strengthen the hypothesis that a disturbance of synaptic homeostasis underlies ASD. PMID:23956174

Corradi, Anna; Fadda, Manuela; Piton, Amélie; Patry, Lysanne; Marte, Antonella; Rossi, Pia; Cadieux-Dion, Maxime; Gauthier, Julie; Lapointe, Line; Mottron, Laurent; Valtorta, Flavia; Rouleau, Guy A.; Fassio, Anna; Benfenati, Fabio; Cossette, Patrick

2014-01-01

202

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

203

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

204

Purple bamboo salt has anticancer activity in TCA8113 cells in vitro and preventive effects on buccal mucosa cancer in mice in vivo  

PubMed Central

Bamboo salt is a traditional healthy salt known in Korea. The in vitro anticancer effects of the salt were evaluated using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay in TCA8113 human tongue carcinoma cells. At 1% concentration, the growth inhibitory rate of purple bamboo salt was 61% higher than that of sea salt (27%). Apoptosis analysis of the cancer cells was carried out using 4,6-diamidino-2-phenylindole (DAPI) staining to investigate the mechanism of the anticancer effects in tongue carcinoma cells. Purple bamboo salt induced a stronger apoptotic effect than sea salt. An Institute of Cancer Research (ICR) mouse buccal mucosa cancer model was established by injecting mice with U14 squamous cell carcinoma cells. Following injection, the wound at the injection site was smeared with salt samples. It was observed that the tumor volumes for the group treated with purple bamboo salt were smaller than those from the sea salt treatment and control groups. The sections of buccal mucosa cancer tissue showed that canceration in the purple bamboo salt group was weaker compared with that in the sea salt group. Similar results were observed in the lesion section of the cervical lymph. Using reverse transcription-polymerase chain reaction (RT-PCR) and western blotting, the purple bamboo salt group demonstrated an increase in Bcl-2-associated X protein (Bax) and a decrease in B cell lymphoma-2 (Bcl-2), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, compared with the sea salt and control groups. The results demonstrated that purple bamboo salt had improved in vivo buccal mucosa cancer preventive activity compared with sea salt in mice. PMID:23403521

ZHAO, XIN; DENG, XIAOXIAO; PARK, KUN-YOUNG; QIU, LIHUA; PANG, LIANG

2013-01-01

205

Electrochemical Gating of Tricarboxylic Acid Cycle in Electricity-Producing Bacterial Cells of Shewanella  

PubMed Central

Energy-conversion systems mediated by bacterial metabolism have recently attracted much attention, and therefore, demands for tuning of bacterial metabolism are increasing. It is widely recognized that intracellular redox atmosphere which is generally tuned by dissolved oxygen concentration or by appropriate selection of an electron acceptor for respiration is one of the important factors determining the bacterial metabolism. In general, electrochemical approaches are valuable for regulation of redox-active objects. However, the intracellular redox conditions are extremely difficult to control electrochemically because of the presence of insulative phospholipid bilayer membranes. In the present work, the limitation can be overcome by use of the bacterial genus Shewanella, which consists of species that are able to respire via cytochromes abundantly expressed in their outer-membrane with solid-state electron acceptors, including anodes. The electrochemical characterization and the gene expression analysis revealed that the activity of tricarboxylic acid (TCA) cycle in Shewanella cells can be reversibly gated simply by changing the anode potential. Importantly, our present results for Shewanella cells cultured in an electrochemical system under poised potential conditions showed the opposite relationship between the current and electron acceptor energy level, and indicate that this unique behavior originates from deactivation of the TCA cycle in the (over-)oxidative region. Our result obtained in this study is the first demonstration of the electrochemical gating of TCA cycle of living cells. And we believe that our findings will contribute to a deeper understanding of redox-dependent regulation systems in living cells, in which the intracellular redox atmosphere is a critical factor determining the regulation of various metabolic and genetic processes. PMID:23977370

Matsuda, Shoichi; Liu, Huan; Kouzuma, Atsushi; Watanabe, Kazuya; Hashimoto, Kazuhito; Nakanishi, Shuji

2013-01-01

206

Metaproteomics Provides Functional Insight into Activated Sludge Wastewater Treatment  

PubMed Central

Background Through identification of highly expressed proteins from a mixed culture activated sludge system this study provides functional evidence of microbial transformations important for enhanced biological phosphorus removal (EBPR). Methodology/Principal Findings A laboratory-scale sequencing batch reactor was successfully operated for different levels of EBPR, removing around 25, 40 and 55 mg/l P. The microbial communities were dominated by the uncultured polyphosphate-accumulating organism “Candidatus Accumulibacter phosphatis”. When EBPR failed, the sludge was dominated by tetrad-forming ?-Proteobacteria. Representative and reproducible 2D gel protein separations were obtained for all sludge samples. 638 protein spots were matched across gels generated from the phosphate removing sludges. 111 of these were excised and 46 proteins were identified using recently available sludge metagenomic sequences. Many of these closely match proteins from “Candidatus Accumulibacter phosphatis” and could be directly linked to the EBPR process. They included enzymes involved in energy generation, polyhydroxyalkanoate synthesis, glycolysis, gluconeogenesis, glycogen synthesis, glyoxylate/TCA cycle, fatty acid ? oxidation, fatty acid synthesis and phosphate transport. Several proteins involved in cellular stress response were detected. Conclusions/Significance Importantly, this study provides direct evidence linking the metabolic activities of “Accumulibacter” to the chemical transformations observed in EBPR. Finally, the results are discussed in relation to current EBPR metabolic models. PMID:18392150

Wilmes, Paul; Wexler, Margaret; Bond, Philip L.

2008-01-01

207

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

208

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

209

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

210

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

211

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

212

The Escherichia coli FtsH protein is a prokaryotic member of a protein family of putative ATPases involved in membrane functions, cell cycle control, and gene expression.  

PubMed Central

The ftsH gene is essential for cell viability in Escherichia coli. We cloned and sequenced the wild-type ftsH gene and the temperature-sensitive ftsH1(Ts) gene. It was suggested that FtsH protein was an integral membrane protein of 70.7 kDa (644 amino acid residues) with a putative ATP-binding domain. The ftsH1(Ts) gene was found to have two base substitutions within the coding sequence corresponding to the amino acid substitutions Glu-463 by Lys and Pro-587 by Ala. Homology search revealed that an approximately 200-amino-acid domain, including the putative ATP-binding sequence, is highly homologous (35 to 48% identical) to the domain found in members of a novel, eukaryotic family of putative ATPases, e.g., Sec18p, Pas1p, CDC48p, and TBP-1, which function in protein transport pathways, peroxisome assembly, cell division cycle, and gene expression, respectively. Possible implications of these observations are discussed. Images PMID:8444796

Tomoyasu, T; Yuki, T; Morimura, S; Mori, H; Yamanaka, K; Niki, H; Hiraga, S; Ogura, T

1993-01-01

213

A decay function model for the integrity loss of rock when subjected to recurrent cycles of freezing–thawing and heating–cooling  

Microsoft Academic Search

Rocks are used in engineering works as monument or building stone and as architectural covering stone. As a result, they can be subjected to recurrent cycles of freezing and thawing and will be subjected to heating and cooling. They loose some of their integrity under these cyclic temperature variations and the more frequent and severe these cycles, the higher the

M Mutlutürk; R Altindag; G Türk

2004-01-01

214

Methylcitrate cycle defines the bactericidal essentiality of isocitrate lyase for survival of Mycobacterium tuberculosis on fatty acids.  

PubMed

Few mutations attenuate Mycobacterium tuberculosis (Mtb) more profoundly than deletion of its isocitrate lyases (ICLs). However, the basis for this attenuation remains incompletely defined. Mtb's ICLs are catalytically bifunctional isocitrate and methylisocitrate lyases required for growth on even and odd chain fatty acids. Here, we report that Mtb's ICLs are essential for survival on both acetate and propionate because of its methylisocitrate lyase (MCL) activity. Lack of MCL activity converts Mtb's methylcitrate cycle into a "dead end" pathway that sequesters tricarboxylic acid (TCA) cycle intermediates into methylcitrate cycle intermediates, depletes gluconeogenic precursors, and results in defects of membrane potential and intrabacterial pH. Activation of an alternative vitamin B12-dependent pathway of propionate metabolism led to selective corrections of TCA cycle activity, membrane potential, and intrabacterial pH that specifically restored survival, but not growth, of ICL-deficient Mtb metabolizing acetate or propionate. These results thus resolve the biochemical basis of essentiality for Mtb's ICLs and survival on fatty acids. PMID:24639517

Eoh, Hyungjin; Rhee, Kyu Y

2014-04-01

215

Menstrual Cycle  

MedlinePLUS

... to the lining of the uterus. If the egg is not fertilized, hormone levels will drop around Day 25 . This signals the next menstrual cycle to begin. The egg will break apart and be shed with the ...

216

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

217

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

218

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.

219

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

PubMed Central

Abstract 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

2014-01-01

220

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

221

Glypican and Biglycan in the Nuclei of Neurons and Glioma Cells: Presence of Functional Nuclear Localization Signals and Dynamic Changes in Glypican During the Cell Cycle  

PubMed Central

We have investigated the expression patterns and subcellular localization in nervous tissue of glypican, a major glycosylphosphatidylinositol-anchored heparan sulfate proteoglycan that is predominantly synthesized by neurons, and of biglycan, a small, leucine-rich chondroitin sulfate proteoglycan. By laser scanning confocal microscopy of rat central nervous tissue and C6 glioma cells, we found that a significant portion of the glypican and biglycan immunoreactivity colocalized with nuclear staining by propidium iodide and was also seen in isolated nuclei. In certain regions, staining was selective, insofar as glypican and biglycan immunoreactivity in the nucleus was seen predominantly in a subpopulation of large spinal cord neurons. The amino acid sequences of both proteoglycans contain potential nuclear localization signals, and these were demonstrated to be functional based on their ability to target ?-galactosidase fusion proteins to the nuclei of transfected 293 cells. Nuclear localization of glypican ?-galactosidase or Fc fusion proteins in transfected 293 cells and C6 glioma cells was greatly reduced or abolished after mutation of the basic amino acids or deletion of the sequence containing the nuclear localization signal, and no nuclear staining was seen in the case of heparan sulfate and chondroitin sulfate proteoglycans that do not possess a nuclear localization signal, such as syndecan-3 or decorin (which is closely related in structure to biglycan). Transfection of COS-1 cells with an epitope-tagged glypican cDNA demonstrated transport of the full-length proteoglycan to the nucleus, and there are also dynamic changes in the pattern of glypican immunoreactivity in the nucleus of C6 cells both during cell division and correlated with different phases of the cell cycle. Our data therefore suggest that in certain cells and central nervous system regions, glypican and biglycan may be involved in the regulation of cell division and survival by directly participating in nuclear processes. PMID:9362504

Liang, Yu; Häring, Monika; Roughley, Peter J.; Margolis, Renée K.; Margolis, Richard U.

1997-01-01

222

Inflammation-mediating cytokine response to acute handcycling exercise with/without functional electrical stimulation-evoked lower-limb cycling.  

PubMed

This feasibility study compared the plasma inflammation-mediating cytokine response to an acute bout of handcycling (HC) with and without the addition of functional electrical stimulation (FES)-evoked lower-limb cycling. On two separate occasions, five recreationally active, community-based participants with motor complete paraplegia (thoracic 5- 7) performed 30 min HC and hybrid exercise (HYB) at a fixed power output. Venous blood samples were collected at rest, immediately postexercise, 1 h postexercise (post+1) and 2 h postexercise (post+2). Plasma interleukin (IL)-6, IL-10, IL-1 receptor antagonist (IL-1ra), adrenaline, and cortisol concentrations were determined via enzyme-linked immunoassay. Plasma IL-6 concentrations were significantly (p < 0.04) elevated (~2.5-fold) at post+1 and post+2 in HYB only. A small (0.5-fold), nonsignificant (p > 0.05) increase in IL-6 was observed at post+1 in HC, with concentrations significantly higher in HYB at post+2 (p < 0.02). Plasma IL-1ra was unaffected in both trials. Although not reaching statistical significance (p = 0.15), a ~1-fold increase in IL-10 concentration was seen in HYB at post+2. In contrast, increases in adrenaline (p < 0.04) and cortisol (p = 0.08) were observed immediately postexercise in HC and HYB. Initial findings suggest paralyzed skeletal muscle releases IL-6 in response to FES-evoked contractions. HYB may provide a greater anti-inflammatory potential in individuals with a thoracic spinal cord injury compared with HC alone. PMID:25144177

Paulson, Thomas A W; Bishop, Nicolette C; Smith, Brett M; Goosey-Tolfrey, Victoria L

2014-01-01

223

Simulation of Marine Nitrogen Cycling as Function of Atmospheric Oxygen: Results of a Coupled C,N,P,O,S Biogeochemical Model Including d15N  

NASA Astrophysics Data System (ADS)

Bioavailable nitrogen is a critical limiting nutrient in the modern marine biosphere. We expect that the rate of denitrification may have been higher in the geologic past due to decreased atmospheric O2 and expanded ocean anoxia. To examine the consequences of this idea, we present numerical simulations of coupled carbon, nitrogen, phosphorus, oxygen, and sulfur cycling as a function of atmospheric oxygen in an ocean with circulation similar to modern conditions. The model has been specifically developed to function over a wide range of ocean redox conditions and has been successfully tested in simulations of both the modern global ocean and Black Sea. Global rates of nitrogen fixation and pelagic denitrification, which are strongly coupled in our default model, reach maximum rates between 25% and 50% of the present atmospheric level of O2 (PAL O2). At 40% PAL O2, the simulated steady-state pelagic denitrification rate is 82.1 Tmol/yr, and the N- fixation rate is 85.7 Tmol/yr. These rates are 8-15× greater than modern estimates. The maximum simulated rate of N-fixation is determined by the N flux required to entirely support export production. At mid- levels of atmospheric oxygen, large areas of the oceans are characterized by a suboxic to anoxic "oxygen minimum zone" between 100m and 1000m depth which is over- and underlain by oxic water. Under these conditions, denitrification in the upper water column is nearly complete, suppressing the ?15N isotopic signal for this process. To test the impact of limitation of N-fixation (e.g. by trace metals, light, temperature) we imposed a cap on the global N-fixation rate. In these simulations, limitation of N-fixation below 50% PAL O2 results in severe N limitation of primary production and low mean oceanic N:P. Our results imply that N limitation may have been chronic at intermediate levels of atmospheric O2. At the same time, low N:P conditions would create evolutionary pressure for efficient N-fixation pathways and high N use efficiency in non-fixing marine phytoplankton, testing the limits of plasticity in the Redfield ratio. If N-fixation were unable to keep up with high rates of denitrification at intermediate levels of atmospheric O2, intense N limitation of Proterozoic marine primary production may have strongly inhibited any further rise of atmospheric O2, thus stabilizing atmospheric O2 at <25% PAL.

Romaniello, S. J.; Derry, L. A.

2008-12-01

224

Cycle Route  

NSDL National Science Digital Library

If you're an avid cyclist or just a neophyte, you'll find this rather unique app most useful. Cycle Route can assist those with a passion for cycling plan out their route based on topography, elevation, main roads, and a range of other variables. Visitors just need to enter their origin and destination and they will be all set. The app returns a range of routes that users can take advantage of and there's also a mobile version as well. This version is compatible with all operating systems.

2013-11-07

225

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

226

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

227

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."

2011-11-23

228

Characterization of RAD9 of Saccharomyces cerevisiae and evidence that its function acts posttranslationally in cell cycle arrest after DNA damage.  

PubMed Central

In eucaryotic cells, incompletely replicated or damaged chromosomes induce cell cycle arrest in G2 before mitosis, and in the yeast Saccharomyces cerevisiae the RAD9 gene is essential for the cell cycle arrest (T.A. Weinert and L. H. Hartwell, Science 241:317-322, 1988). In this report, we extend the analysis of RAD9-dependent cell cycle control. We found that both induction of RAD9-dependent arrest in G2 and recovery from arrest could occur in the presence of the protein synthesis inhibitor cycloheximide, showing that the mechanism of RAD9-dependent control involves a posttranslational mechanism(s). We have isolated and determined the DNA sequence of the RAD9 gene, confirming the DNA sequence reported previously (R. H. Schiestl, P. Reynolds, S. Prakash, and L. Prakash, Mol. Cell. Biol. 9:1882-1886, 1989). The predicted protein sequence for the Rad9 protein bears no similarity to sequences of known proteins. We also found that synthesis of the RAD9 transcript in the cell cycle was constitutive and not induced by X-irradiation. We constructed yeast cells containing a complete deletion of the RAD9 gene; the rad9 null mutants were viable, sensitive to X- and UV irradiation, and defective for cell cycle arrest after DNA damage. Although Rad+ and rad9 delta cells had similar growth rates and cell cycle kinetics in unirradiated cells, the spontaneous rate of chromosome loss (in unirradiated cells) was elevated 7- to 21-fold in rad9 delta cells. These studies show that in the presence of induced or endogenous DNA damage, RAD9 is a negative regulator that inhibits progression from G2 in order to preserve cell viability and to maintain the fidelity of chromosome transmission. Images PMID:2247073

Weinert, T A; Hartwell, L H

1990-01-01

229

Mitochondrial metabolism of sexual and asexual blood stages of the malaria parasite Plasmodium falciparum  

PubMed Central

Background The carbon metabolism of the blood stages of Plasmodium falciparum, comprising rapidly dividing asexual stages and non-dividing gametocytes, is thought to be highly streamlined, with glycolysis providing most of the cellular ATP. However, these parasitic stages express all the enzymes needed for a canonical mitochondrial tricarboxylic acid (TCA) cycle, and it was recently proposed that they may catabolize glutamine via an atypical branched TCA cycle. Whether these stages catabolize glucose in the TCA cycle and what is the functional significance of mitochondrial metabolism remains unresolved. Results We reassessed the central carbon metabolism of P. falciparum asexual and sexual blood stages, by metabolically labeling each stage with 13C-glucose and 13C-glutamine, and analyzing isotopic enrichment in key pathways using mass spectrometry. In contrast to previous findings, we found that carbon skeletons derived from both glucose and glutamine are catabolized in a canonical oxidative TCA cycle in both the asexual and sexual blood stages. Flux of glucose carbon skeletons into the TCA cycle is low in the asexual blood stages, with glutamine providing most of the carbon skeletons, but increases dramatically in the gametocyte stages. Increased glucose catabolism in the gametocyte TCA cycle was associated with increased glucose uptake, suggesting that the energy requirements of this stage are high. Significantly, whereas chemical inhibition of the TCA cycle had little effect on the growth or viability of asexual stages, inhibition of the gametocyte TCA cycle led to arrested development and death. Conclusions Our metabolomics approach has allowed us to revise current models of P. falciparum carbon metabolism. In particular, we found that both asexual and sexual blood stages utilize a conventional TCA cycle to catabolize glucose and glutamine. Gametocyte differentiation is associated with a programmed remodeling of central carbon metabolism that may be required for parasite survival either before or after uptake by the mosquito vector. The increased sensitivity of gametocyte stages to TCA-cycle inhibitors provides a potential target for transmission-blocking drugs. PMID:23763941

2013-01-01

230

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

Microsoft Academic Search

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,

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

2011-01-01

231

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

232

A methodology for estimating seasonal cycles of atmospheric CO2 resulting from terrestrial net ecosystem exchange (NEE) fluxes using the Transcom T3L2 pulse-response functions  

NASA Astrophysics Data System (ADS)

We present a method for translating modeled terrestrial net ecosystem exchange (NEE) fluxes of carbon into the corresponding seasonal cycles in atmospheric CO2. The method is based on the pulse-response functions from the Transcom 3 Level 2 (T3L2) atmospheric tracer transport model (ATM) intercomparison. The new pulse-response method is considerably faster than a full forward ATM simulation, allowing CO2 seasonal cycles to be computed in seconds, rather than the days or weeks required for a forward simulation. Further, the results provide an estimate of the range of transport uncertainty across 13 different ATMs associated with the translation of surface NEE fluxes into an atmospheric signal. We evaluate the method against the results of archived forward ATM simulations from T3L2. The latter are also used to estimate the uncertainties associated with oceanic and fossil fuel influences. We present a regional breakdown at selected monitoring sites of the contribution to the atmospheric CO2 cycle from the 11 different T3L2 land regions. A test case of the pulse-response code, forced by NEE fluxes from the Community Land Model, suggests that for many terrestrial models, discrepancies between model results and observed atmospheric CO2 cycles will be large enough to clearly transcend ATM uncertainties.

Nevison, C. D.; Baker, D. F.; Gurney, K. R.

2012-09-01

233

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

234

Advanced regenerative absorption refrigeration cycles  

DOEpatents

Multi-effect regenerative absorption cycles which provide a high coefficient of performance (COP) at relatively high input temperatures. An absorber-coupled double-effect regenerative cycle (ADR cycle) (10) is provided having a single-effect absorption cycle (SEA cycle) (11) as a topping subcycle and a single-effect regenerative absorption cycle (1R cycle) (12) as a bottoming subcycle. The SEA cycle (11) includes a boiler (13), a condenser (21), an expansion device (28), an evaporator (31), and an absorber (40), all operatively connected together. The 1R cycle (12) includes a multistage boiler (48), a multi-stage resorber (51), a multisection regenerator (49) and also uses the condenser (21), expansion device (28) and evaporator (31) of the SEA topping subcycle (11), all operatively connected together. External heat is applied to the SEA boiler (13) for operation up to about 500 degrees F., with most of the high pressure vapor going to the condenser (21) and evaporator (31) being generated by the regenerator (49). The substantially adiabatic and isothermal functioning of the SER subcycle (12) provides a high COP. For higher input temperatures of up to 700 degrees F., another SEA cycle (111) is used as a topping subcycle, with the absorber (140) of the topping subcycle being heat coupled to the boiler (13) of an ADR cycle (10). The 1R cycle (12) itself is an improvement in that all resorber stages (50b-f) have a portion of their output pumped to boiling conduits (71a-f) through the regenerator (49), which conduits are connected to and at the same pressure as the highest pressure stage (48a) of the 1R multistage boiler (48).

Dao, Kim (14 Nace Ave., Piedmont, CA 94611)

1990-01-01

235

Functionalization of carbon nanotubes with water-insoluble porphyrin in ionic liquid: direct electrochemistry and highly sensitive amperometric biosensing for trichloroacetic acid.  

PubMed

A functional composite of single-walled carbon nanotubes (SWNTs) with hematin, a water-insoluble porphyrin, was first prepared in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]) ionic liquid. The novel composite in ionic liquid was characterized by scanning electron microscopy, ultraviolet absorption spectroscopy, and electrochemical impedance spectroscopy, and showed a pair of direct redox peaks of the Fe(III)/Fe(II) couple. The composite-[BMIM][PF(6)]-modified glassy carbon electrode showed excellent electrocatalytic activity toward the reduction of trichloroacetic acid (TCA) in neutral media due to the synergic effect among SWNTs, [BMIM][PF(6)], and porphyrin, which led to a highly sensitive and stable amperometric biosensor for TCA with a linear range from 9.0x10(-7) to 1.4x10(-4) M. The detection limit was 3.8x10(-7) M at a signal-to-noise ratio of 3. The TCA biosensor had good analytical performance, such as rapid response, good reproducibility, and acceptable accuracy, and could be successfully used for the detection of residual TCA in polluted water. The functional composite in ionic liquid provides a facile way to not only obtain the direct electrochemistry of water-insoluble porphyrin, but also construct novel biosensors for monitoring analytes in real environmental samples. PMID:19058268

Tu, Wenwen; Lei, Jianping; Ju, Huangxian

2009-01-01

236

Metformin and phenformin deplete tricarboxylic acid cycle and glycolytic intermediates during cell transformation and NTPs in cancer stem cells  

PubMed Central

Metformin, a first-line diabetes drug linked to cancer prevention in retrospective clinical analyses, inhibits cellular transformation and selectively kills breast cancer stem cells (CSCs). Although a few metabolic effects of metformin and the related biguanide phenformin have been investigated in established cancer cell lines, the global metabolic impact of biguanides during the process of neoplastic transformation and in CSCs is unknown. Here, we use LC/MS/MS metabolomics (>200 metabolites) to assess metabolic changes induced by metformin and phenformin in an Src-inducible model of cellular transformation and in mammosphere-derived breast CSCs. Although phenformin is the more potent biguanide in both systems, the metabolic profiles of these drugs are remarkably similar, although not identical. During the process of cellular transformation, biguanide treatment prevents the boost in glycolytic intermediates at a specific stage of the pathway and coordinately decreases tricarboxylic acid (TCA) cycle intermediates. In contrast, in breast CSCs, biguanides have a modest effect on glycolytic and TCA cycle intermediates, but they strongly deplete nucleotide triphosphates and may impede nucleotide synthesis. These metabolic profiles are consistent with the idea that biguanides inhibit mitochondrial complex 1, but they indicate that their metabolic effects differ depending on the stage of cellular transformation. PMID:25002509

Janzer, Andreas; German, Natalie J.; Gonzalez-Herrera, Karina N.; Asara, John M.; Haigis, Marcia C.; Struhl, Kevin

2014-01-01

237

Tissue persistence and vaccine efficacy of tricarboxylic acid cycle and one-carbon metabolism mutant strains of Edwardsiella ictaluri.  

PubMed

Edwardsiella ictaluri causes enteric septicemia in fish. Recently, we reported construction of E. ictaluri mutants with single and double gene deletions in tricarboxylic acid cycle (TCA) and one-carbon (C-1) metabolism. Here, we report the tissue persistence, virulence, and vaccine efficacy of TCA cycle (Ei?sdhC, Ei?frdA, and Ei?mdh), C-1 metabolism (Ei?gcvP and Ei?glyA), and combination mutants (Ei?frdA?sdhC, Ei?gcvP?sdhC, Ei?mdh?sdhC, and Ei?gcvP?glyA) in channel catfish. The tissue persistence study showed that Ei?sdhC, Ei?frdA, Ei?frdA?sdhC, and Ei?gcvP?sdhC were able to invade catfish and persist until 11 days post-infection. Vaccination of catfish fingerlings with all nine mutants provided significant (P<0.05) protection against subsequent challenge with the virulent parental strain. Vaccinated catfish fingerlings had 100% survival when subsequently challenged by immersion with wild-type E. ictaluri except for Ei?gcvP?glyA and Ei?gcvP. Mutant Ei?gcvP?sdhC was found to be very good at protecting catfish fry, as evidenced by 10-fold higher survival compared to non-vaccinated fish. PMID:24837777

Dahal, Neeti; Abdelhamed, Hossam; Karsi, Attila; Lawrence, Mark L

2014-06-30

238

The Glutamine-Glutamate/GABA Cycle: Function, Regional Differences in Glutamate and GABA Production and Effects of Interference with GABA Metabolism.  

PubMed

The operation of a glutamine-glutamate/GABA cycle in the brain consisting of the transfer of glutamine from astrocytes to neurons and neurotransmitter glutamate or GABA from neurons to astrocytes is a well-known concept. In neurons, glutamine is not only used for energy production and protein synthesis, as in other cells, but is also an essential precursor for biosynthesis of amino acid neurotransmitters. An excellent tool for the study of glutamine transfer from astrocytes to neurons is [(14)C]acetate or [(13)C]acetate and the glial specific enzyme inhibitors, i.e. the glutamine synthetase inhibitor methionine sulfoximine and the tricarboxylic acid cycle (aconitase) inhibitors fluoro-acetate and -citrate. Acetate is metabolized exclusively by glial cells, and [(13)C]acetate is thus capable when used in combination with magnetic resonance spectroscopy or mass spectrometry, to provide information about glutamine transfer. The present review will give information about glutamine trafficking and the tools used to map it as exemplified by discussions of published work employing brain cell cultures as well as intact animals. It will be documented that considerably more glutamine is transferred from astrocytes to glutamatergic than to GABAergic neurons. However, glutamine does have an important role in GABAergic neurons despite their capability of re-utilizing their neurotransmitter by re-uptake. PMID:25380696

Walls, Anne B; Waagepetersen, Helle S; Bak, Lasse K; Schousboe, Arne; Sonnewald, Ursula

2014-11-01

239

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

240

Accumulation of RXR alpha during activation of cycling human T lymphocytes: modulation of RXRE transactivation function by mitogen-activated protein kinase pathways.  

PubMed

We have previously reported that the activation of resting human immature peripheral blood T (PBT) lymphocytes is associated with the loss of retinoid X receptor alpha (RXRalpha) expression. In the present study, we have demonstrated that, unlike resting cells, activation of cycling human mature PBT lymphocytes, and T lymphocyte leukemia cell lines is accompanied by the accumulation of RXRalpha mRNA and protein. Interestingly, cyclosporin A further augmented RXRalpha expression, indicating the involvement of calcineurin pathways in the process. 9-cis retinoic acid inhibited the accumulation, suggesting that retinoids can regulate the synthesis of their own receptors during T cell activation. Transfection analysis in Jurkat cells, using RXRE-dependent reporter assays, showed that RXRalpha accumulated during T cell activation was transcriptionally inactive. To investigate the mechanism of such inhibition, the role of two mitogen-activated protein kinase pathways, c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), in modulating RXRE-dependent transcription, was explored. The expression of constitutively active MAP/ERK kinase kinase 1 (MEKK1) inhibited RXRE-dependent transcription, whereas dominant negative MEKK1 increased the transcription, indicating the involvement of JNK signaling pathways in the process. In contrast, expression of constitutively active MEK1, which activates ERK pathway, enhanced RXRE-dependent activation. When both were activated simultaneously, JNK pathway was dominant over ERK pathway and resulted in inhibition of RXRE-mediated transcription. These data demonstrate a dual regulatory control of RXRalpha expression during the activation of resting and cycling T lymphocytes and indicate a dynamic balance between JNK and ERK pathways in modulating RXRE-mediated transactivation. PMID:11035054

Ishaq, M; Fan, M; Natarajan, V

2000-10-15

241

Bioremediation of chlorimuron-ethyl-contaminated soil by Hansschlegelia sp. strain CHL1 and the changes of indigenous microbial population and N-cycling function genes during the bioremediation process.  

PubMed

Long-term and excessive application of the herbicide chlorimuron-ethyl has led to soil degradation and crop rotation barriers. In the current study, we isolated bacterial strain Hansschlegelia sp. CHL1, which can utilize chlorimuron-ethyl as its sole carbon and energy source, and investigated its application in soil bioremediation. Indigenous microbial populations and N-cycling function in the soil were also investigated during the bioremediation process by monitoring the copy numbers of bacterial and fungal marker genes, as well as N-cycling functional genes (nifH, amoA, nirS, and nirK). Results showed that >95% of chlorimuron-ethyl could be degraded within 45 days in soils inoculated with CHL1. Inoculation at two time points resulted in a higher remediation efficiency and longer survival time than a single inoculation. At the end of the 60-day incubation, the copy numbers of most indicator genes were recovered to the level of the control, even in the single-inoculation soils. A double inoculation was necessary for recovery of nifH. However, the abundance of nirK and ammonia-oxidizing bacterial genes were significantly inhibited regardless of inoculum. The results suggested that CHL1 is effective for the remediation of chlorimuron-ethyl-contaminated soil, and could partially reduce the toxic effects of chlorimuron-ethyl on soil microorganisms. PMID:24794985

Yang, Liqiang; Li, Xinyu; Li, Xu; Su, Zhencheng; Zhang, Chenggang; Zhang, Huiwen

2014-06-15

242

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 ...

Lopez, Mrs.

2009-07-09

243

Mitochondria-targeted antioxidant promotes recovery of skeletal muscle mitochondrial function after burn trauma assessed by in vivo 31P nuclear magnetic resonance and electron paramagnetic resonance spectroscopy.  

PubMed

Burn injury causes a major systemic catabolic response that is associated with mitochondrial dysfunction in skeletal muscle. We investigated the effects of the mitochondria-targeted peptide antioxidant Szeto-Schiller 31 (SS-31) on skeletal muscle in a mouse burn model using in vivo phosphorus-31 nuclear magnetic resonance ((31)P NMR) spectroscopy to noninvasively measure high-energy phosphate levels; mitochondrial aconitase activity measurements that directly correlate with TCA cycle flux, as measured by gas chromatography mass spectrometry (GC-MS); and electron paramagnetic resonance (EPR) to assess oxidative stress. At 6 h postburn, the oxidative ATP synthesis rate was increased 5-fold in burned mice given a single dose of SS-31 relative to untreated burned mice (P=0.002). Furthermore, SS-31 administration in burned animals decreased mitochondrial aconitase activity back to control levels. EPR revealed a recovery in redox status of the SS-31-treated burn group compared to the untreated burn group (P<0.05). Our multidisciplinary convergent results suggest that SS-31 promotes recovery of mitochondrial function after burn injury by increasing ATP synthesis rate, improving mitochondrial redox status, and restoring mitochondrial coupling. These findings suggest use of noninvasive in vivo NMR and complementary EPR offers an approach to monitor the effectiveness of mitochondrial protective agents in alleviating burn injury symptoms. PMID:23482635

Righi, Valeria; Constantinou, Caterina; Mintzopoulos, Dionyssios; Khan, Nadeem; Mupparaju, S P; Rahme, Laurence G; Swartz, Harold M; Szeto, Hazel H; Tompkins, Ronald G; Tzika, A Aria

2013-06-01

244

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

245

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

PubMed

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

246

Evidence for DNA-PK-dependent and -independent DNA double-strand break repair pathways in mammalian cells as a function of the cell cycle.  

PubMed Central

Mice homozygous for the scid (severe combined immune deficiency) mutation are defective in the repair of DNA double-strand breaks (DSBs) and are consequently very X-ray sensitive and defective in the lymphoid V(D)J recombination process. Recently, a strong candidate for the scid gene has been identified as the catalytic subunit of the DNA-dependent protein kinase (DNA-PK) complex. Here, we show that the activity of the DNA-PK complex is regulated in a cell cycle-dependent manner, with peaks of activity found at the G1/early S phase and again at the G2 phase in wild-type cells. Interestingly, only the deficit of the G1/early S phase DNA-PK activity correlated with an increased hypersensitivity to X-irradiation and a DNA DSB repair deficit in synchronized scid pre-B cells. Finally, we demonstrate that the DNA-PK activity found at the G2 phase may be required for exit from a DNA damage-induced G2 checkpoint arrest. These observations suggest the presence of two pathways (DNA-PK-dependent and -independent) of illegitimate mammalian DNA DSB repair and two distinct roles (DNA DSB repair and G2 checkpoint traversal) for DNA-PK in the cellular response to ionizing radiation. PMID:9032269

Lee, S E; Mitchell, R A; Cheng, A; Hendrickson, E A

1997-01-01

247

HIV Life Cycle  

MedlinePLUS

... the connection between HIV medicines and the HIV life cycle? Without treatment, HIV infection gradually destroys the ... HIV. What are the stages of the HIV life cycle? To understand the HIV life cycle, it ...

248

Final Report - The Xanthophyll Cycle  

SciTech Connect

The xanthophyll cycle is a ubiquitous activity in higher plants. A major function of the cycle is to protect the photosynthetic system from the potentially damaging effects of high light by dissipating excess energy that might otherwise damage the photosynthetic apparatus harmlessly as heat by a process termed non-photochemical quenching (NFQ). This research focused on investigating the dynamics of the relationship between PsbS, subunit PSII protein required for NPQ, and zeaxanthin by perturbing the natural relationship of these components by overexpression of PsbS, violaxanthin de-epoxidase (VDE), and PsbS-VDE in tobacco. The effects of these treatments showed that the relationship between NPQ and zeaxanthin formation is more complex than previously indicated from studies carried out under high light. It is postulated that the xanthophyll cycle functions as a type of signal-transduction system within the thylakoid membrane. Recent studies in model lipid systems demonstrated that zeaxanthin exerts feedback inhibition on violaxanthin de-epoxidase. This feedback inhibition is consistent with the lipid phase functioning as a modulating factor in the dynamics of the cycle's operation. While this research and those in other laboratories have defined both the biochemistry and molecular mechanism of the cycle's operation, especially for violaxanthin de-epoxidase, there is yet insufficient knowledge that explains the ubiquitous presence of the cycle in all higher plants and a related cycle in diatoms. Antisense VDE tobacco plants (work carried out under another grant) withstood the high-light environment in Hawaii over one generation. Thus, it is speculated that the protective system was essential for survival in earth's high-light earth environment over multiple generations. The proposed signal transduction protective system, however, may explain the ability of the protective system to modulate or adapt to a range of environments.

Harry Yamamato

2005-04-21

249

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

250

A novel Arabidopsis type 1 protein phosphatase is highly expressed in male and female tissues and functionally complements a conditional cell cycle mutant of Aspergillus.  

PubMed

Type 1 protein phosphatases are very highly conserved throughout eukaryotes where they regulate a number of key metabolic and morphogenetic processes. A cDNA, AtPP1bg, representing a new member of the type 1 protein phosphatase gene family in Arabidopsis has been isolated on the basis of hybridization with the Aspergillus bimG protein phosphatase gene. The AtPP1bg gene potentially encodes a 37 kDa protein very closely related to PP1 but with divergent N- and C-termini. The predicted amino acid sequence shows 71% identity to the ORF of the bimG gene. When expressed in Aspergillus under the alcA promoter, this phosphatase complements the temperature-sensitive bimG11 mutation allowing nearly normal vegetative growth at 37 degrees C (but not at 42 degrees C). Notably, the plant PP1 does not support morphogenesis (conidiation) at 37 degrees C. This may indicate that conidophore formation has particular phosphatase requirement(s) which the plant PP1 cannot supply. The pattern of expression of the AtPP1bg transcript has been studied during development of the plant. In situ hybridization of Arabidopsis with antisense probes shows that this phosphatase gene is expressed at a low level throughout the plant, but is strongly upregulated within developing flowers, especially in the tapetum, the developing and mature pollen and in the ovaries. This implies that the AtPP1bg either has a specialized role in the formation of these organs, or that there is an increased requirement for protein phosphatase 1 at these stages. It was found that the level of AtPP1bg transcript, as judged by the relative intensity of staining in different cells within the floral meristems, did not vary during the cell cycle. PMID:7773310

Arundhati, A; Feiler, H; Traas, J; Zhang, H; Lunness, P A; Doonan, J H

1995-05-01

251

Hypothalamic-pituitary-adrenal (HPA) axis function in the California mouse (Peromyscus californicus): Changes in baseline activity, reactivity, and fecal excretion of glucocorticoids across the diurnal cycle  

PubMed Central

The California mouse, Peromyscus californicus, is an increasingly popular animal model in behavioral, neural, and endocrine studies, but little is known about its baseline hypothalamicpituitary-adrenal (HPA) axis activity or HPA responses to stressors. We characterized plasma corticosterone (CORT) concentrations in P. californicus under baseline conditions across the diurnal cycle, in response to pharmacological manipulation of the HPA axis, and in response to a variety of stressors at different times of day. In addition, we explored the use of fecal samples to monitor adrenocortical activity non-invasively. California mice have very high baseline levels of circulating CORT that change markedly over 24 hours, but that do not differ between the sexes. This species may be somewhat glucocorticoid-resistant in comparison to other rodents as a relatively high dose of dexamethasone (5 mg/kg, s.c.) was required to suppress plasma CORT for 8 h post-injection. CORT responses to stressors and ACTH injection differed with time of day, as CORT concentrations were elevated more readily during the morning (inactive period) than in the evening (active period) when compared to time-matched control. Data from 3H-CORT injection studies show that the time course for excretion of fecal CORT, or glucocorticoid metabolites, differs with time of injection. Mice injected in the evening excreted the majority of fecal radioactivity 2–4 h post-injection whereas mice injected during the morning did so at 14–16 h post-injection. Unfortunately, the antibody we used does not adequately bind the most prevalent fecal glucocorticoid metabolites and therefore we could not validate its use for fecal assays. PMID:23026495

Harris, Breanna N.; Saltzman, Wendy; de Jong, Trynke R.; Milnes, Matthew R.

2012-01-01

252

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

253

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

254

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

255

No evidence for parasitism-linked changes in immune function or oxidative physiology over the annual cycle of an avian species.  

PubMed

Temporally changing environmental conditions occur in most parts of the world and can exert strong pressure on the immune defense of organisms. Seasonality may result in changes in physiological traits over the year, and such changes may be essential for the optimization of defense against infections. Evidence from field and laboratory studies suggest the existence of links between environmental conditions, such as infection risk, and the ability of animals to mount an immune response or to overcome infections; however, the importance of parasites in mediating seasonal change in immune defense is still debated. In this study, we test the hypothesis that seasonal change in immune function and connected physiological traits is related to parasite infection. We sampled captive house sparrows (Passer domesticus) once every 2 mo over 14 mo and compared the annual variation in 12 measures of condition, immune function, antioxidant status, and oxidative damage among birds naturally infested with coccidians or medicated against these parasites. We found significant variation in 10 of 12 traits over the year. However, we found little support for parasite-mediated change in immune function and oxidative status in captive house sparrows. Of the 12 measures, only one was slightly affected by parasite treatment. In support of the absence of any effect of coccidians on the annual profile of the condition and physiological traits, we found no consistent relationships between the intensity of infestation and these response variables over the year. Our results show that chronic coccidian infections have limited effect on the seasonal changing of physiological traits and that the patterns of these measures are probably more affected by acute infection and/or virulent parasite strains. PMID:25244384

Pap, Péter L; Sesarman, Alina; Vágási, Csongor I; Buehler, Deborah M; P?tra?, Laura; Versteegh, Maaike A; Banciu, Manuela

2014-01-01

256

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

257

The Q-cycle reviewed: how well does a monomeric mechanism of the bc1 complex account for the function of a dimeric complex?  

PubMed Central

Recent progress in understanding the Q-cycle mechanism of the bc1 complex is reviewed. The data strongly support a mechanism in which the Qo-site operates through a reaction in which the first electron transfer from ubiquinol to the oxidized iron-sulfur protein is the rate determining step for the overall process. The reaction involves a proton-coupled electron transfer down a hydrogen bond between the ubiquinol and a histidine ligand of the [2Fe-2S] cluster, in which the unfavorable protonic configuration contributes a substantial part of the activation barrier. The reaction is endergonic, and the products are an unstable ubisemiquinone at the Qo-site, and the reduced iron-sulfur protein, the extrinsic mobile domain of which is now free to dissociate and move away from the site to deliver an electron to cyt c1 and liberate the H+. When oxidation of the semiquinone is prevented, it participates in bypass reactions, including superoxide generation if O2 is available. When the b-heme chain is available as acceptor, the semiquinone is oxidized in a process in which the proton is passed to the glutamate of the conserved –PEWY- sequence, and the semiquinone anion passes its electron to heme bL to form the product ubiquinone. The rate is rapid compared to the limiting reaction, and would require movement of the semiquinone closer to heme bL to enhance the rate constant. The acceptor reactions at the Qi-site are still controversial, but likely involve a “two-electron gate” in which a stable semiquinone stores an electron. Possible mechanisms to explain the cytb150 phenomenon are discussed, and the information from pulsed EPR studies about the structure of the intermediate state is reviewed. The mechanism discussed is applicable to a monomeric bc1 complex. We discuss evidence in the literature that has been interpreted as shown that the dimeric structure participates in a more complicated mechanism involving electron transfer across the dimer interface. We show from myxothiazol titrations and mutational analysis of Tyr-199, which is at the interface between monomers, that no such inter-monomer electron transfer is detected at the level of the bL hemes. We show from analysis of strains with mutations at Asn-221 that there are coulombic interactions between the b-hemes in a monomer. The data can also be interpreted as showing similar coulombic interaction across the dimer interface, and we discuss mechanistic implications. PMID:18501698

Crofts, Antony R.; Holland, J. Todd; Victoria, Doreen; Kolling, Derrick R.J.; Dikanov, Sergei A.; Gilbreth, Ryan; Lhee, Sangmoon; Kuras, Richard; Kuras, Mariana Guergova

2008-01-01

258

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 Central

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.

2012-01-01

259

A generalized approach to thermodynamic cycle analysis  

Microsoft Academic Search

Thermodynamic functions based on generalized equations of state, along with physical properties estimation methods were used to predict, with acceptable accuracy, the thermodynamic properties in a system power cycle analysis. The performance of a binary power system with a Rankine bottoming cycle using various fluids was examined. The generalized approach is compared with analyses based on actual thermodynamic data and

C. D. Henry III

1977-01-01

260

CLASS DESCRIPTIONS CYCLING SERIES  

E-print Network

CLASS DESCRIPTIONS CYCLING SERIES CYCLING Whether you are an avid cyclist or just beginning, this class will provide a high-intensity cardio workout. Ride around the world in all types of terrain, while for all participants. This class is open to 30 participants. ULTIMATE CYCLING Ultimate Cycling

Pittendrigh, Barry

261

Novel Tools to Analyze the Function of Salmonella Effectors Show That SvpB Ectopic Expression Induces Cell Cycle Arrest in Tumor Cells  

PubMed Central

In order to further characterize its role in pathogenesis and to establish whether its overproduction can lead to eukaryotic tumor cell death, Salmonella strains able to express its virulence factor SpvB (an ADP-ribosyl transferase enzyme) in a salicylate-inducible way have been constructed and analyzed in different eukaryotic tumor cell lines. To do so, the bacterial strains bearing the expression system have been constructed in a ?purD background, which allows control of bacterial proliferation inside the eukaryotic cell. In the absence of bacterial proliferation, salicylate-induced SpvB production resulted in activation of caspases 3 and 7 and apoptotic cell death. The results clearly indicated that controlled SpvB production leads to F-actin depolimerization and either G1/S or G2/M phase arrest in all cell lines tested, thus shedding light on the function of SpvB in Salmonella pathogenesis. In the first place, the combined control of protein production by salicylate regulated vectors and bacterial growth by adenine concentration offers the possibility to study the role of Salmonella effectors during eukaryotic cells infection. In the second place, the salicylate-controlled expression of SpvB by the bacterium provides a way to evaluate the potential of other homologous or heterologous proteins as antitumor agents, and, eventually to construct novel potential tools for cancer therapy, given that Salmonella preferentially proliferates in tumors. PMID:24205236

Mesa-Pereira, Beatriz; Medina, Carlos; Camacho, Eva María; Flores, Amando; Santero, Eduardo

2013-01-01

262

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

263

Effects of intrathecal triamincinolone-acetonide treatment in MS patients with therapy-resistant spasticity.  

PubMed

Objectives:Multiple sclerosis (MS) is an autoimmune disease affecting young people and is a major cause of disability. In the course of time, disability progresses and symptoms like spasticity may occur. Spasticity is a major cost factor in MS patients. Various agents are approved for the treatment of spasticity, but each of those agents may have several side effects. Intrathecally administered steroids (triamcinolone-acetonide (TCA)) may be efficient in treating spasticity in patients with lesions in the spinal cord and no response to first-line therapeutics. The aim of this study is to show effects of TCA treatment on clinical parameters in patients with MS.Methods:This multicentre open label study included 54 patients with MS. The clinical outcome parameters were spasticity, disability, maximum walking distance, bladder function and quality of life. All patients received physiotherapy in addition to TCA treatment to obtain optimal effects on clinical parameters.Results:Spasticity, maximum walking distance as well as disability improved significantly (P?0.001) during TCA applications. Bladder function improved in every seventh patient.Conclusion:We observed the effects of intrathecally administered TCA on different clinical parameters including bladder function. TCA administration is a safe method to treat different symptoms in MS patients. Longitudinal trials with repeated TCA cycles are needed to show long-term effects. Besides TCA treatment, physiotherapy contributes to the improvement of clinical parameters.Spinal Cord advance online publication, 16 September 2014; doi:10.1038/sc.2014.155. PMID:25224601

Kamin, F; Rommer, P S; Abu-Mugheisib, M; Koehler, W; Hoffmann, F; Winkelmann, A; Benecke, R; Zettl, U K

2014-09-16

264

Functional laser speckle imaging of cerebral blood flow under hypothermia  

NASA Astrophysics Data System (ADS)

Hypothermia can unintentionally occur in daily life, e.g., in cardiovascular surgery or applied as therapeutics in the neurosciences critical care unit. So far, the temperature-induced spatiotemporal responses of the neural function have not been fully understood. In this study, we investigated the functional change in cerebral blood flow (CBF), accompanied with neuronal activation, by laser speckle imaging (LSI) during hypothermia. Laser speckle images from Sprague-Dawley rats (n = 8, male) were acquired under normothermia (37°C) and moderate hypothermia (32°C). For each animal, 10 trials of electrical hindpaw stimulation were delivered under both temperatures. Using registered laser speckle contrast analysis and temporal clustering analysis (TCA), we found a delayed response peak and a prolonged response window under hypothermia. Hypothermia also decreased the activation area and the amplitude of the peak CBF. The combination of LSI and TCA is a high-resolution functional imaging method to investigate the spatiotemporal neurovascular coupling in both normal and pathological brain functions.

Li, Minheng; Miao, Peng; Zhu, Yisheng; Tong, Shanbao

2011-08-01

265

Multiple Rankine topping cycles  

SciTech Connect

The efficiency of a Rankine cycle is primarily determined by the temperatures of heat addition and rejection. However, no working fluid has been identified which will operate in a Rankine cycle over an extremely wide temperature range. Multiple Rankine topping cycles offer a technique for achieving high thermal efficiencies in power plants by allowing the use of several working fluids. This paper gives a history of Rankine topping cycles, presents an analysis for the calculation of the overall efficiency of a three-module multiple Rankine cycle, and presents results from a case study for a sodium-mercury-water cycle.

McWhirter, J.D. [Argonne National Lab., Idaho Falls, ID (United States). Engineering Div.]|[Idaho State Univ., Pocatello, ID (United States). Coll. of Engineering

1995-07-01

266

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

267

What-a-cycle  

NSDL National Science Digital Library

In this activity, students act as water molecules and travel through parts of the water cycle (ocean, atmosphere, clouds, glaciers, snow, rivers, lakes, ground, aquifer), noting on a hydrological cycle diagram the pathway traveled.

Jetstream - On-line School for Weather

268

Dynamic simulation of a solar powered Rankine cycle\\/vapor compression cycle \\/RC\\/VCC  

Microsoft Academic Search

A simple solar air conditioning system incorporating a Rankine cycle vapor compression cycle (RC\\/VCC) cooling subsystem is simulated by means of equations. RC\\/VCC overall (heating-to-cooling) cycle coefficient of performance (OCCOP) is reported as a function of input temperatures for sample design point models and for sample off-design models. Off-design capacity performance of a sample RC\\/VCC subsystem is reported. Sample RC\\/VCC

R. W. Allen; D. K. Anand; A. N. Egrican

1978-01-01

269

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.

California Academy of Sciences

2008-01-01

270

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.

271

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

272

The Rock Cycle  

NSDL National Science Digital Library

Create a poster about the rock cycle! Directions: Make a poster about the rock cycle. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about the rock cycle. (5 points each) (15 points) Write at least a three sentence summary of your poster ...

Walls, Mrs.

2011-01-30

273

The Anderson Quin Cycle  

Microsoft Academic Search

The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since

J. H. Anderson; W. M. Bilbow

1993-01-01

274

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.

Baker, Ms.

2011-04-18

275

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. 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.

276

Flashlets: Carnot Cycle  

NSDL National Science Digital Library

This site shows the fundamentals of the Carnot Cycle through a Flash simulation. Using a Pressure vs Volume (PV) plot the user observes how the cycle is carried out by different types of compressions and expansions. The simulation also includes an engine, constituted of a piston and a rod, illustrating the various processes in a Carnot Cycle.

Fowler, Michael; Ching, Jacquie H.

2008-08-08

277

Multiple Rankine topping cycles  

Microsoft Academic Search

The efficiency of a Rankine cycle is primarily determined by the temperatures of heat addition and rejection. However, no working fluid has been identified which will operate in a Rankine cycle over an extremely wide temperature range. Multiple Rankine topping cycles offer a technique for achieving high thermal efficiencies in power plants by allowing the use of several working fluids.

McWhirter

1995-01-01

278

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.

279

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

280

Algebraic cycles and Stark-Heegner points Henri Darmon  

E-print Network

calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4 Algebraic cycles and de Rham based on algebraic cycles, Rankin triple product L-functions, and p-adic families of modular formsAlgebraic cycles and Stark-Heegner points Henri Darmon Victor Rotger April 27, 2012 #12;2 #12

Rotger, Víctor

281

Algebraic cycles and Stark-Heegner points Henri Darmon  

E-print Network

calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4 Algebraic cycles and de Rham based on algebraic cycles, Rankin triple product L-functions, and p-adic families of modular formsAlgebraic cycles and Stark-Heegner points Henri Darmon Victor Rotger July 2, 2011 #12;2 #12

Cushing, Jim. M.

282

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

283

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.

284

Budding yeast protein extraction and purification for the study of function, interactions, and post-translational modifications.  

PubMed

Homogenization by bead beating is a fast and efficient way to release DNA, RNA, proteins, and metabolites from budding yeast cells, which are notoriously hard to disrupt. Here we describe the use of a bead mill homogenizer for the extraction of proteins into buffers optimized to maintain the functions, interactions and post-translational modifications of proteins. Logarithmically growing cells expressing the protein of interest are grown in a liquid growth media of choice. The growth media may be supplemented with reagents to induce protein expression from inducible promoters (e.g. galactose), synchronize cell cycle stage (e.g. nocodazole), or inhibit proteasome function (e.g. MG132). Cells are then pelleted and resuspended in a suitable buffer containing protease and/or phosphatase inhibitors and are either processed immediately or frozen in liquid nitrogen for later use. Homogenization is accomplished by six cycles of 20 sec bead-beating (5.5 m/sec), each followed by one minute incubation on ice. The resulting homogenate is cleared by centrifugation and small particulates can be removed by filtration. The resulting cleared whole cell extract (WCE) is precipitated using 20% TCA for direct analysis of total proteins by SDS-PAGE followed by Western blotting. Extracts are also suitable for affinity purification of specific proteins, the detection of post-translational modifications, or the analysis of co-purifying proteins. As is the case for most protein purification protocols, some enzymes and proteins may require unique conditions or buffer compositions for their purification and others may be unstable or insoluble under the conditions stated. In the latter case, the protocol presented may provide a useful starting point to empirically determine the best bead-beating strategy for protein extraction and purification. We show the extraction and purification of an epitope-tagged SUMO E3 ligase, Siz1, a cell cycle regulated protein that becomes both sumoylated and phosphorylated, as well as a SUMO-targeted ubiquitin ligase subunit, Slx5. PMID:24300101

Szymanski, Eva Paige; Kerscher, Oliver

2013-01-01

285

Cryogenic\\/elevated temperature cycling induced leakage paths in PMCs  

Microsoft Academic Search

Three structural carbon\\/polymer composites (IM7\\/977-2, IM7\\/977-3, and IM7\\/5250-4) were thermally cycled between liquid nitrogen (LN2) temperature and an elevated temperature of 120 or 177 °C. The extent of ply-level micro-cracks was measured as a function of cycles up to 1000 cycles as one indicator of suitability for cryogenic containment applications. The choice of material systems, lay-ups, and thermal cycles allowed

Vernon T. Bechel; John D. Camping; Ran Y. Kim

2005-01-01

286

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.

Pyle, Eric

287

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

288

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

289

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.

290

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.

Sciences, California A.

2008-01-01

291

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

292

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 ...

Hughes, Mr.

2006-02-18

293

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.

294

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.

Cramer, Catherine; Engle-Belknap, Cheryl A.; Repeta, Daniel; Welty, David J.; Frashure, Kim; Drouin, Pamela

2006-01-01

295

Life Cycle of Plants  

NSDL National Science Digital Library

What is the life cycle of plants? First, look at pictures of Apple seeds , A Peach Seed , and Corn Seeds . Second, look at pictures of a Tomato Seedling , a Coconut Seedling , and Lettuce Seedlings . Third, look at pictures of Adult Palm Trees , Adult Rice Plants , and an Adult Grape Vine . Next, read about Seed Growth and How Seeds Start to Grow. After doing so, watch the Plant Life Cycle Video and fill out the Plant Life Cycle Organizer . ...

Johnson, Miss

2011-04-07

296

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.

2011-04-29

297

The Hydrologic Cycle  

NSDL National Science Digital Library

View the five processes of the hydrologic cycle in this interactive resource adapted from NASA in which animations illustrate condensation, precipitation, infiltration, runoff, and evapotranspiration.

2005-12-17

298

Functional epileptic network in left mesial temporal lobe epilepsy detected using resting fMRI.  

PubMed

The purpose of this study was to determine transient functional signal activity in a small, homogeneous group of left temporal lobe epilepsy (TLE) patients, without the use of EEG; and to use one of these activated regions to identify a possible epileptogenic network across the whole brain in this group. Resting functional MRI scanning was performed on five left TLE patients who underwent selective amygdalohippocampectomy resulting in seizure control and 10 healthy control subjects. Activation maps of functional signal peaks were calculated using a data-driven analysis, 2dTCA, across the group of patients. In addition to the expected region of activation in the left anterior hippocampus, the results of the 2dTCA analysis revealed activity in the bilateral insular cortex and default-mode network which are not commonly reported using fMRI, but are supported by other electrical and functional changes. The region of activation corresponding to the anterior hippocampal region of resection (presumably the epileptogenic region) was used as a seed region for fMRI functional connectivity analysis. This revealed increased negative connectivity in the patients as compared to controls across a network including thalamic, brainstem, frontal and parietal regions consistent with theories of inhibited function in subcortical and cortical structures during ictal propagation. PMID:19945255

Morgan, Victoria L; Gore, John C; Abou-Khalil, Bassel

2010-02-01

299

Rock Cycle Animation  

NSDL National Science Digital Library

The rock cycle is an ongoing process in which rock, driven by tectonic processes such as volcanoes and earthquakes, the surface processes of weathering and erosion, and compaction, is created, destroyed, and recycled. This interactive feature introduces viewers to the processes which come into play as rock proceeds through the various portions of the cycle.

2005-11-01

300

Rock Cycle Animation  

NSDL National Science Digital Library

The rock cycle is an ongoing process in which rock, driven by tectonic processes such as volcanoes and earthquakes, the surface processes of weathering and erosion, and compaction, is created, destroyed, and recycled. This interactive feature introduces viewers to the processes which come into play as rock proceeds through the various portions of the cycle.

2011-06-22

301

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

302

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

303

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.

304

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

305

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 Earthâs system.

306

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

307

Rock Cycle Animation  

NSDL National Science Digital Library

The rock cycle is an ongoing process in which rock, driven by tectonic processes such as volcanoes and earthquakes, the surface processes of weathering and erosion, and compaction, is created, destroyed, and recycled. This interactive feature introduces viewers to the processes which come into play as rock proceeds through the various portions of the cycle.

308

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

309

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

310

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

311

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,

312

The Hydrologic Cycle  

NSDL National Science Digital Library

This explanation of the hydrologic cycle discusses evaporation, transpiration, condensation, precipitation, runoff, percolation, groundwater, and the water table. There is a diagram and a description of each as well as a discussion of the dynamics of the cycle, which powered by the Sun. In addition there are links that lead to all parts of the Properties of Water menu.

313

Predicting the Sunspot Cycle  

NASA Technical Reports Server (NTRS)

The 11-year sunspot cycle was discovered by an amateur astronomer in 1844. Visual and photographic observations of sunspots have been made by both amateurs and professionals over the last 400 years. These observations provide key statistical information about the sunspot cycle that do allow for predictions of future activity. However, sunspots and the sunspot cycle are magnetic in nature. For the last 100 years these magnetic measurements have been acquired and used exclusively by professional astronomers to gain new information about the nature of the solar activity cycle. Recently, magnetic dynamo models have evolved to the stage where they can assimilate past data and provide predictions. With the advent of the Internet and open data policies, amateurs now have equal access to the same data used by professionals and equal opportunities to contribute (but, alas, without pay). This talk will describe some of the more useful prediction techniques and reveal what they say about the intensity of the upcoming sunspot cycle.

Hathaway, David H.

2009-01-01

314

Bimodality and the Hale cycle  

NASA Astrophysics Data System (ADS)

Because of the bimodal distribution of sunspot cycle periods, the Hale cycle (or double sunspot cycle) should show evidence of modulation between 20 and 24 yr, with the Hale cycle having an average length of about 22 yr. Indeed, such a modulation is observed. Rsum (the sum of monthly mean sunspot numbers over consecutively paired sunspot cycles) and RM, the maximum smoothed sunspot number are given for cycles 1 - 21 and estimated for cycles 22 and 23.

Wilson, Robert M.

1988-09-01

315

Applying Machine Learners to GUI Specifications in Formulating Early Life Cycle Project Estimations  

E-print Network

1 Applying Machine Learners to GUI Specifications in Formulating Early Life Cycle Project and reliable early life cycle project estimates remains an open issue in the software engineering discipline cycle. Most early life cycle estimation models (e.g. COCOMO II, Function Point Analysis) use either

Boetticher, Gary D.

316

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

317

Natural and Urban "Stormwater" Water Cycles  

NSDL National Science Digital Library

Through an overview of the components of the hydrologic cycle and the important roles they play in the design of engineered systems, students' awareness of the world's limited fresh water resources is heightened. The hydrologic cycle affects everyone and is the single most critical component to life on Earth. Students examine in detail the water cycle components and phase transitions, and then learn how water moves through the human-made urban environment. This urban "stormwater" water cycle is influenced by the pervasive existence of impervious surfaces that limit the amount of infiltration, resulting in high levels of stormwater runoff, limited groundwater replenishment and reduced groundwater flow. Students show their understanding of the process by writing a description of the path of a water droplet through the urban water cycle, from the droplet's point of view. The lesson lays the groundwork for rest of the unit, so students can begin to think about what they might do to modify the urban "stormwater" water cycle so that it functions more like the natural water cycle. A PowerPoint® presentation and handout are provided.

Water Awareness Research and Education (WARE) Research Experience for Teachers (RET),

318

The Anderson Quin Cycle  

SciTech Connect

The objective of this study was to make a more refined evaluation of the Anderson Quin Cycle based on most recent information on the performance of various elements that will be used in the Anderson Quin Cycle. My original estimate of the work plan for evaluating and optimizing the Anderson Quin Cycle called for 7000 man hours of work. Since this grant was limited to 2150 man hours, we could not expect to achieve all the objectives within the allotted period of work. However, the most relevant program objectives have been completed as reported here. The analysis generally confirms the results originally estimated in my paper on the subject. (Ref. 2) Further optimizations should show even higher efficiencies. The Anderson Quin Cycle (US Patent applied for) basically consists of 5 elements in the power cycle: A refrigeration system to cool and clean the inlet air before it enters the compressor that supplies air for the gas turbine; a gas turbine consisting of a compressor, combustor, and turbine; a steam boiler and steam turbine system using the heat from the exhaust gas out of the gas turbine; a vapor turbine cycle, which utilizes the condensed heat from the exhaust of the steam turbine and the exhaust gas heat leaving the steam boiler to operate a vapor turbine cycle which utilizes another fluid than water, in this case isobutane; and the fifth element consists of a gas cooler and heat pump system, which removes the heat from the exhaust gas to lower its temperature essentially to atmospheric temperature, and at the same time permits treatment of the exhaust gas to remove acid components such as sulfur dioxide and nitrogen oxides. Current industry accepted component characteristics were incorporated in the performance analysis of the overall cycle, ensuring accurate and meaningful operating predictions. The characteristics and performance of each of the elements are described. The thermal efficiency of the optimized calculated Anderson Quin Cycle is 62 percent.

Anderson, J.H.; Bilbow, W.M.

1993-03-18

319

The Rock Cycle Experiments  

NSDL National Science Digital Library

Maintained by the BBC Education Web site, The Rock Cycle Experiments page contains ten activities related to the rock cycle, beginning with weathering and ending with the uplift of rocks. Each activity pops up after clicking the link within the very well done interactive diagram of the rock cycle. The activities are simple but effective; for example, the transportation lesson has students run water through sand to see its effects. The hands-on experience of the activities helps reinforce the learning and of course makes it fun.

King, Chris.

320

The Water Cycle  

NSDL National Science Digital Library

Did you know that the water we use today is the same water found on Earth millions of years ago? The Earth constantly uses and recycles water in a process called the water cycle. In this lesson, learners explore the four phases of the water cycle. In the investigation Rain in a Jar, learners use hot water and ice to create condensation and a tiny cloud. In Making a Terrarium, learners create an ecosystem and water cycle by growing plants in a closed environment. Investigation spans several days.

2013-12-18

321

The Rock Cycle  

ERIC Educational Resources Information Center

Presents a rock cycle diagram suitable for use at the secondary or introductory college levels which separates rocks formed on and below the surface, includes organic materials, and separates products from processes. (SL)

Singh, Raman J.; Bushee, Jonathan

1977-01-01

322

Urea Cycle Disease Overview  

MedlinePLUS

... the body’s process to breakdown products, such as ammonia. Ammonia is a product of protein digestion and the ... cycle is required for the body to excrete ammonia. In patients with partial enzyme deficiencies, the first ...

323

The Crayon Rock Cycle  

NSDL National Science Digital Library

In this activity, learners use crayons to draw conclusions about rocks and the rock cycle. Learners form crayons ((which can be "weathered"âheated, compressed and cooledâlike rocks) into models of sedimentary, metamorphic, and igneous rocks.

Muller, Eric

2004-01-01

324

The Carbon Cycle  

NSDL National Science Digital Library

This narrated slide presentation shows the carbon cycle, looking at various parts of this biogeochemical sequence by examining carbon reservoirs and how carbon is exchanged among them and the atmosphere.

Thinkport

325

Frog life cycle  

NSDL National Science Digital Library

The life cycle of a frog includes the egg stage, tadpole stage, froglet stage, and adult frog stage. Tadpoles live in water and use gills to breathe. They develop lungs as they mature into frogs and live on land.

Olivia Worland (Purdue University;Biological Sciences)

2008-05-23

326

Cycle isolation monitoring  

SciTech Connect

There are many factors to monitor in power plants, but one that is frequently overlooked is cycle isolation. Often this is an area where plant personnel can find 'low hanging fruit' with great return on investment, especially high energy valve leakage. This type of leakage leads to increased heat rate, potential valve damage and lost generation. The fundamental question to ask is 'What is 100 Btu/kW-hr of heat rate worth to your plant? On a 600 MW coal-fired power plant, a 1% leakage can lead to an 81 Btu/kW-hr impact on the main steam cycle and a 64 Btu/kW-hr impact on the hot reheat cycle. The article gives advice on methods to assist in detecting leaking valves and to monitor cycle isolation. A software product, TP. Plus-CIM was designed to estimate flow rates of potentially leaking valves.

Svensen, L.M. III; Zeigler, J.R.; Todd, F.D.; Alder, G.C. [Santee Copper, Moncks Corner, SC (United States)

2009-07-15

327

Mining the Learning Cycle.  

ERIC Educational Resources Information Center

Describes an approach that uses the learning cycle to meaningfully teach students about mineral properties while alleviating the tedious nature of identifying mineral specimens. Discusses mineral properties, cooperative learning, and mineral identification. (JRH)

Hemler, Debra; King, Hobart

1996-01-01

328

The Rock Cycle  

NSDL National Science Digital Library

This site from Satellite Geodesy describes the rock cycle, and quantitative ways to estimate how long geological features took to form. Popcorn is used to demonstrate half-life and radio-active decay, which is used to date rocks.

Tauxe, Lisa; Geodesy, Satellite

329

The Rock Cycle  

NSDL National Science Digital Library

This site contains a basic explanation of the rock cycle along with information on the difference between a rock and a mineral and a description of the three types of rocks (igneous, metamorphic, and sedimentary). The site also describes the crust, mantle, outer core, and inner core, which are the four different layers of the Earth. In addition, it has a diagram of the rock cycle showing its relationship to the Theory of Plate Tectonics.

330

The Rock Cycle  

NSDL National Science Digital Library

This interactive website explains rock cycle processes including igneous, metamorphic and sedimentary. Students can view an animated version of the rock cycle, learn about each step in the process, and take an online quiz to test their knowledge for each section. Understanding earth's deep past through the process that recycles rocks can help students develop concepts of the world in three dimensions and grasp the time-scale of geological changes.

2008-01-01

331

Understanding the Carbon Cycle  

NSDL National Science Digital Library

In this unit, students use Internet resources, slide presentations, and modeling to explain how understanding the carbon cycle helps scientists understand and prepare for global climate change, what might happen if sources of carbon produced more than sinks could remove, and what might happen if sinks absorbed more than sources produced. They should understand how the carbon cycle affects various life forms and the role that carbon plays in their lives. Procedures, a glossary, assessments, and scoring rubrics are provided.

332

The Real Biofuel Cycles  

Microsoft Academic Search

This paper analyzes energy efficiency of the industrial corn-ethanol cycle and brackets energy efficiency of the switchgrass-cellulosic ethanol cycle. In particular, it critically evaluates the publications by Farrell et al. (2006a; 2006b) and Shapouri, Wang, et al. (Wang, 2001; Shapouri et al., 2002; Shapouri et al., 2003; Shapouri and McAloon, 2004). It is demonstrated that in a net-energy analysis of

Tad W. Patzek

333

Mosquito Life Cycle  

NSDL National Science Digital Library

In this activity, learners build a plastic emergence chamber (or use purchased "mini mosquito breeder") to observe and analyze the mosquito life cycle. Learners record daily observations for 8-14 days by counting the number of larvae, pupae, and adults present in the chamber. This resource includes background information about the mosquito life cycle and mosquitoes as disease vectors plus a link to a mosquito reference manual.

Howard Hughes Medical Institute

2010-01-01

334

Modeling the glutamate–glutamine neurotransmitter cycle  

PubMed Central

Glutamate is the principal excitatory neurotransmitter in brain. Although it is rapidly synthesized from glucose in neural tissues the biochemical processes for replenishing the neurotransmitter glutamate after glutamate release involve the glutamate–glutamine cycle. Numerous in vivo 13C magnetic resonance spectroscopy (MRS) experiments since 1994 by different laboratories have consistently concluded: (1) the glutamate–glutamine cycle is a major metabolic pathway with a flux rate substantially greater than those suggested by early studies of cell cultures and brain slices; (2) the glutamate–glutamine cycle is coupled to a large portion of the total energy demand of brain function. The dual roles of glutamate as the principal neurotransmitter in the CNS and as a key metabolite linking carbon and nitrogen metabolism make it possible to probe glutamate neurotransmitter cycling using MRS by measuring the labeling kinetics of glutamate and glutamine. At the same time, comparing to non-amino acid neurotransmitters, the added complexity makes it more challenging to quantitatively separate neurotransmission events from metabolism. Over the past few years our understanding of the neuronal-astroglial two-compartment metabolic model of the glutamate–glutamine cycle has been greatly advanced. In particular, the importance of isotopic dilution of glutamine in determining the glutamate–glutamine cycling rate using [1?13C] or [1,6-13C2] glucose has been demonstrated and reproduced by different laboratories. In this article, recent developments in the two-compartment modeling of the glutamate–glutamine cycle are reviewed. In particular, the effects of isotopic dilution of glutamine on various labeling strategies for determining the glutamate–glutamine cycling rate are analyzed. Experimental strategies for measuring the glutamate–glutamine cycling flux that are insensitive to isotopic dilution of glutamine are also suggested. PMID:23372548

Shen, Jun

2012-01-01

335

Solar Cycle Predictions  

NASA Technical Reports Server (NTRS)

Solar cycle predictions are needed to plan long-term space missions; just like weather predictions are needed to plan the launch. Fleets of satellites circle the Earth collecting many types of science data, protecting astronauts, and relaying information. All of these satellites are sensitive at some level to solar cycle effects. Predictions of drag on LEO spacecraft are one of the most important. Launching a satellite with less propellant can mean a higher orbit, but unanticipated solar activity and increased drag can make that a Pyrrhic victory as you consume the reduced propellant load more rapidly. Energetic events at the Sun can produce crippling radiation storms that endanger all assets in space. Solar cycle predictions also anticipate the shortwave emissions that cause degradation of solar panels. Testing solar dynamo theories by quantitative predictions of what will happen in 5-20 years is the next arena for solar cycle predictions. A summary and analysis of 75 predictions of the amplitude of the upcoming Solar Cycle 24 is presented. The current state of solar cycle predictions and some anticipations how those predictions could be made more accurate in the future will be discussed.

Pesnell, William Dean

2012-01-01

336

Malone cycle refrigerator development  

SciTech Connect

This paper describes the progress made in demonstrating a Malone Cycle Refrigerator/Freezer. The Malone cycle is similar to the Stirling cycle but uses a supercritical fluid in place of real gas. In the approach, solid-metal diaphragms are used to seal and sweep the working volumes against the high working fluid pressures required in Malone cycle machines. This feature eliminates the friction and leakage that accounted for nearly half the losses in the best piston-defined Malone cycle machines built to date. The authors successfully built a Malone cycle refrigerator that: (1) used CO{sub 2} as the working fluid, (2) operated at pressures up to 19.3 Mpa (2,800 psi), (3) achieved a cold end metal temperatures of {minus}29 C ({minus}20 F), and (4) produced over 400 Watts of cooling at near ambient temperatures. The critical diaphragm components operated flawlessly throughout characterization and performance testing, supporting the conclusion of high reliability based on analysis of fatigue date and actual strain measurements.

Shimko, M.A.; Crowley, C.J.

1999-07-01

337

LIFE CYCLE DESIGN OF AIR INTAKE MANIFOLDS  

EPA Science Inventory

This life cycle design project was a collaborative effort between the Center for Sustainable Systems (formerly National Pollution Prevention Center) at the University of Michigan, a cross functional team at Ford, and the National Risk Management Research Laboratory of the U.S. En...

338

Teaching Real Business Cycles to Undergraduates  

ERIC Educational Resources Information Center

The authors review the graphical approach to teaching the real business cycle model introduced in Barro. They then look at where this approach cuts corners and suggest refinements. Finally, they compare graphical and exact models by means of impulse-response functions. The graphical models yield reliable qualitative results. Sizable quantitative…

Brevik, Frode; Gartner, Manfred

2007-01-01

339

Effect of pulse duty cycle on Inconel 718 laser welds  

NASA Technical Reports Server (NTRS)

Crack sensitive Inconel 718 was laser pulse welded using a 3.0 kW CO2 laser. Weld shape, structure, and porosity were recorded as a function of the pulse duty cycle. Within the matrix studied, the welds were found to be optimized at a high (17 ms on, 7 ms off) duty cycle. These welds were superior in appearance and lack of porosity to both low duty cycle and CW welds.

McCay, M. H.; McCay, T. D.; Dahotre, N. B.; Sharp, C. M.; Sedghinasab, A.; Gopinathan, S.

1989-01-01

340

Heterotrimeric G Protein Cycle  

NSDL National Science Digital Library

This teaching resource provides two types of insight into the heterotrimeric G protein cycle. The interactive 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). G proteins are comprised of two subunits, ? and an obligate dimer ??. The structure movie shows an computer-generated interpretation of the conformational changes in the ? subunit that are associated with GTP binding and hydrolysis. The basic G protein cycle consists of a G protein-coupled receptor (GPCR) activating the G protein by promoting the exchange of guanosine triphosphate (GTP) for guanosine diphosphate (GDP), which allows the ? and ?? subunits to separate and activate downstream targets. The signal is terminated when the ? subunit hydrolyzes GTP and the ? and ?? subunits reassociate. The animation allows the user to choose to play the cycle with or without additional regulators and see the effect on the signaling duration. RGS stimulates the GTPase activity of the ? subunit and terminates signaling faster. GDI prevents the dissociation of GDP from the ? subunit and blocks reassociation of the ?? subunit, thus extending ?? signaling. GEF enhances the rate of GTP loading in the presence of an activated receptor thus accelerating the speed of the response.

Anita M. Preininger (Vanderbilt University Medical Center; Department of Pharmacology; REV)

2004-02-03

341

Helium process cycle  

DOEpatents

A unique process cycle and apparatus design separates the consumer (cryogenic) load return flow from most of the recycle return flow of a refrigerator and/or liquefier process cycle. The refrigerator and/or liquefier process recycle return flow is recompressed by a multi-stage compressor set and the consumer load return flow is recompressed by an independent consumer load compressor set that maintains a desirable constant suction pressure using a consumer load bypass control valve and the consumer load return pressure control valve that controls the consumer load compressor's suction pressure. The discharge pressure of this consumer load compressor is thereby allowed to float at the intermediate pressure in between the first and second stage recycle compressor sets. Utilizing the unique gas management valve regulation, the unique process cycle and apparatus design in which the consumer load return flow is separate from the recycle return flow, the pressure ratios of each recycle compressor stage and all main pressures associated with the recycle return flow are allowed to vary naturally, thus providing a naturally regulated and balanced floating pressure process cycle that maintains optimal efficiency at design and off-design process cycle capacity and conditions automatically.

Ganni, Venkatarao (Yorktown, VA)

2008-08-12

342

Thermodynamics of an idealized hydrologic cycle  

NASA Astrophysics Data System (ADS)

The diurnal hydrologic cycle, a sequence of evapotranspiration, boundary layer growth, moist convection, and precipitation, is described in a thermodynamic framework, assuming an atmosphere composed solely of water. This idealized cycle is shown to be equivalent to an abbreviated version of the classical Rankine cycle where not all the water vapor is condensed. Energy and entropy fluxes of the processes involved in the cycle are quantified using the reversible approximation as a function of the quality of the liquid-vapor mixture (the ratio of the residual background vapor and the total mass of water) and the different temperatures at which evaporation and condensation take place. The proposed framework allows quantitative estimates of the net work (which is used by the cycle to drive the atmospheric circulation and dissipated by various frictional forces and nonidealities) as well as of the thermodynamic efficiency of the cycle. Possible extensions of the idealized framework relating to the role of dry air and the inclusion of various irreversible processes are also discussed.

Konings, Alexandra G.; Feng, Xue; Molini, Annalisa; Manzoni, Stefano; Vico, Giulia; Porporato, Amilcare

2012-05-01

343

The Water Cycle  

NSDL National Science Digital Library

This site provides information about precipitation, evaporation, condensation, surface runoff, infiltration and transpiration, which are all part of the water cycle, a complex process that not only gives us water to drink and fish to eat, but also weather patterns that help grow our crops. The site has four sections. The introduction presents the overall concept while the second section covers each of the six parts of the cycle in detail. In the third part, The Cycle, the dynamic process is stressed and a diagram is included. Cloud Formation is the final section and it covers factors that control the size and shape of clouds such as heat, seasons, mountain ranges, bodies of water, volcanic eruptions, and even global warming. In addition, cloud nomenclature is discussed with an explanation of the advent of such cloud names as cumulonimbus, nimbostratus, cirrocumulus, and altostratus.

344

Solar magnetic cycle  

NASA Technical Reports Server (NTRS)

Using NSO/KP magnetograms, the pattern and rate of the emergence of magnetic flux and the development of the large-scale patterns of unipolar fields are considered in terms of the solar magnetic cycle. Magnetic flux emerges in active regions at an average rate of 2 x 10(exp 21) Mx/day, approximately 10 times the estimated rate in ephemeral regions. Observations are presented that demonstrate that the large-scale unipolar fields originate in active regions and activity nests. For cycle 21, the net contribution of ephemeral regions to the axial dipole moment of the Sun is positive, and is of opposite sign to that of active regions. Its amplitude is smaller by a factor of 6, assuming an average lifetime of ephemeral regions of 8 hours. Active regions larger than 4500 Mm(sup 2) are the primary contributor to the cycle variation of Sun's axial dipole moment.

Harvey, Karen L.

1993-01-01

345

Superfluid thermodynamic cycle refrigerator  

DOEpatents

A cryogenic refrigerator cools a heat source by cyclically concentrating and diluting the amount of .sup.3 He in a single phase .sup.3 He-.sup.4 He solution. The .sup.3 He in superfluid .sup.4 He acts in a manner of an ideal gas in a vacuum. Thus, refrigeration is obtained using any conventional thermal cycle, but preferably a Stirling or Carnot cycle. A single phase solution of liquid .sup.3 He at an initial concentration in superfluid .sup.4 He is contained in a first variable volume connected to a second variable volume through a superleak device that enables free passage of .sup.4 He while restricting passage of .sup.3 He. The .sup.3 He is compressed (concentrated) and expanded (diluted) in a phased manner to carry out the selected thermal cycle to remove heat from the heat load for cooling below 1 K.

Swift, Gregory W. (Santa Fe, NM); Kotsubo, Vincent Y. (La Canada, CA)

1992-01-01

346

The Other Water Cycle  

NSDL National Science Digital Library

For students who have already been introduced to the water cycle, this lesson is intended as a logical follow-up. Students learn about human impacts on the water cycle that create a pathway for pollutants beginning with urban development and joining the natural water cycle as surface runoff. The extent of surface runoff in an area depends on the permeability of the materials in the ground. Permeability is the degree to which water or other liquids are able to flow through a material. Different substances such as soil, gravel, sand and asphalt have varying levels of permeability. In this lesson, along with the associated activity, students learn about permeability and compare the permeability of several different materials for the purpose of engineering landscape drainage systems.

Engineering K-Phd Program

347

Reduced DRAM cycle times with extended data-out  

Microsoft Academic Search

As system speeds increase, DRAM manufacturers are developing methods to decrease the cycle times of DRAMs. The most common version of DRAM is FAST PAGE MODE (FPM) but the addition of a feature known as extended data-out (EDO) may become more common because it allows shorter page cycle times with only a minor functional change from FP. Because the device

1996-01-01

348

Decentralized Feedback Structures of a Vapor Compression Cycle System  

Microsoft Academic Search

In vapor compression cycle systems, it is desirable to effectively control the thermodynamic cycle by controlling the thermodynamic states of the refrigerant. By controlling the thermodynamic states with an inner loop, supervisory algorithms can manage critical functions and objectives such as maintaining superheat and maximizing the coefficient of performance. In practice, it is generally preferred to tune multiple single-input-single-output (SISO)

Neera Jain; Bin Li; Michael Keir; Brandon Hencey; Andrew Alleyne

2010-01-01

349

Evidence for urea cycle activity in Sporosarcina ureae  

Microsoft Academic Search

Sporosarcina ureae BS 860, a motile, sporeforming coccus, possesses the enzymes required for a functioning urea (ornithine) cycle. This is only the second known example of urea cycle activity in a prokaryote. Specific activities are reported for ornithine carbamoyltransferase, argininosuccinase, arginase, and urease. Although argininosuccinate synthetase activity could not be detected directly in crude cell extracts, indirect evidence from radiocarbon

Stephen E. Gruninger; Manuel Goldman

1988-01-01

350

Annual Cycles of Steroid Hormone Production, Gonad Development, and Reproductive  

E-print Network

Annual Cycles of Steroid Hormone Production, Gonad Development, and Reproductive Behavior and ultimate function of this extended preovulatory mating are un- known. Annual cycles of the gonadal steroids their choice of mates. This estuary sample population shows higher ab- solute steroid levels and distinct

Tricas, Timothy C.

351

Rescue of corpus luteum function with peri-ovulatory HCG supplementation in IVF\\/ICSI GnRH antagonist cycles in which ovulation was triggered with a GnRH agonist: a pilot study  

Microsoft Academic Search

Previous studies found a poor clinical outcome when a GnRH agonist (GnRHa) was used to trigger ovulation in GnRH antagonist IVF\\/ICSI cycles. This study aimed to determine the clinical and endocrine effects as well the optimal timing of HCG supplementation. Forty-five normogonadotrophic IVF\\/ICSI patients following a flexible antagonist protocol were prospectively randomized (sealed envelopes) to triggering of ovulation with a

P Humaidan; L Bungum; M Bungum; C Yding Andersen

2006-01-01

352

Global water cycle  

NASA Technical Reports Server (NTRS)

The primary objective is to determine the scope and interactions of the global water cycle with all components of the Earth system and to understand how it stimulates and regulates changes on both global and regional scales. The following subject areas are covered: (1) water vapor variability; (2) multi-phase water analysis; (3) diabatic heating; (4) MSU (Microwave Sounding Unit) temperature analysis; (5) Optimal precipitation and streamflow analysis; (6) CCM (Community Climate Model) hydrological cycle; (7) CCM1 climate sensitivity to lower boundary forcing; and (8) mesoscale modeling of atmosphere/surface interaction.

Robertson, Franklin R.; Christy, John R.; Goodman, Steven J.; Miller, Tim L.; Fitzjarrald, Dan; Lapenta, Bill; Wang, Shouping

1991-01-01

353

Soil Biogeochemical Cycles  

NSDL National Science Digital Library

This group activity charges students with teaching their colleagues about the biogeochemical cycle of one key soil element (e.g., either C, N, S, P, Ca, or Fe). Students are given a single class period to summarize their knowledge and to develop a lesson that includes (1) an organized, 5-8 minute oral presentation, (2) a graphical, conceptual model of their assigned element's soil-biogeochemical cycle, and (3) a list of discussion questions with which to engage their colleagues on the other teams. A second class session is used to refine and to expand upon the submitted models as necessary.

Colin Robins

354

Carbon Cycle and Life  

NSDL National Science Digital Library

In this lesson, learners explore the steps in the carbon cycle and draw conclusions about the importance of the carbon cycle in the planetary temperature system. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes, prerequisite concepts, common misconceptions, student journal and reading. This is lesson six in the Astro-Venture Geology Training Unit that was developed to increase students' awareness of and interest in astrobiology and the many career opportunities that utilize science, math and technology skills. The lessons are designed for educators to use with the Astro-Venture multimedia modules.

355

The Carbon Cycle Game  

NSDL National Science Digital Library

In this activity, learners take on the role of a carbon atom and record which reservoirs in the carbon cycle they visit. Learners will compare and contrast their trip with those of other learners to discover information about sources and sinks, and residence times of the different reservoirs. Ocean processes are highlighted to allow the educator to define the biological pump and explain its importance to climate. Helping learners understand the carbon cycle is essential to their understanding of the causes and consequences of climate change.

2012-10-05

356

Metabolic Regulation of the Cell Cycle  

PubMed Central

There is a growing appreciation that metabolic signals are integrated and coupled to cell cycle progression. However, the molecular wiring that connects nutrient availability, biosynthetic intermediates and energetic balance to the core cell cycle machinery remains incompletely understood. In this review, we explore the recent progress in this area with particular emphasis on how nutrient and energetic status is sensed within the cell to ultimately regulate cell growth and division. The role these pathways play in normal cell function including stem cell biology is also discussed. Furthermore, we describe the growing appreciation that dysregulation of these pathways might contribute to a variety of pathological conditions including metabolic diseases and tumor formation. PMID:23890700

Lee, In Hye; Finkel, Toren

2013-01-01

357

Fuel Cycle System Analysis Handbook  

SciTech Connect

This Handbook aims to improve understanding and communication regarding nuclear fuel cycle options. It is intended to assist DOE, Campaign Managers, and other presenters prepare presentations and reports. When looking for information, check here. The Handbook generally includes few details of how calculations were performed, which can be found by consulting references provided to the reader. The Handbook emphasizes results in the form of graphics and diagrams, with only enough text to explain the graphic, to ensure that the messages associated with the graphic is clear, and to explain key assumptions and methods that cause the graphed results. Some of the material is new and is not found in previous reports, for example: (1) Section 3 has system-level mass flow diagrams for 0-tier (once-through), 1-tier (UOX to CR=0.50 fast reactor), and 2-tier (UOX to MOX-Pu to CR=0.50 fast reactor) scenarios - at both static and dynamic equilibrium. (2) To help inform fast reactor transuranic (TRU) conversion ratio and uranium supply behavior, section 5 provides the sustainable fast reactor growth rate as a function of TRU conversion ratio. (3) To help clarify the difference in recycling Pu, NpPu, NpPuAm, and all-TRU, section 5 provides mass fraction, gamma, and neutron emission for those four cases for MOX, heterogeneous LWR IMF (assemblies mixing IMF and UOX pins), and a CR=0.50 fast reactor. There are data for the first 10 LWR recycle passes and equilibrium. (4) Section 6 provides information on the cycle length, planned and unplanned outages, and TRU enrichment as a function of fast reactor TRU conversion ratio, as well as the dilution of TRU feedstock by uranium in making fast reactor fuel. (The recovered uranium is considered to be more pure than recovered TRU.) The latter parameter impacts the required TRU impurity limits specified by the Fuels Campaign. (5) Section 7 provides flows for an 800-tonne UOX separation plant. (6) To complement 'tornado' economic uncertainty diagrams, which show at a glance combined uncertainty information, section 9.2 has a new set of simpler graphs that show the impact on fuel cycle costs for once through, 1-tier, and 2-tier scenarios as a function of key input parameters.

Steven J. Piet; Brent W. Dixon; Dirk Gombert; Edward A. Hoffman; Gretchen E. Matthern; Kent A. Williams

2009-06-01

358

Water Cycle Missions for the Next Decade  

NASA Astrophysics Data System (ADS)

The global water cycle describes the circulation of water as a vital and dynamic substance in its liquid, solid, and vapor phases as it moves through the atmosphere, oceans and land. Life in its many forms exists because of water, and modern civilization depends on learning how to live within the constraints imposed by the availability of water. The scientific challenge posed by the need to observe the global water cycle is to integrate in situ and space-borne observations to quantify the key water-cycle state variables and fluxes. The vision to address that challenge is a series of Earth observation missions that will measure the states, stocks, flows, and residence times of water on regional to global scales followed by a series of coordinated missions that will address the processes, on a global scale, that underlie variability and changes in water in all its three phases. The accompanying societal challenge is to foster the improved use of water data and information as a basis for enlightened management of water resources, to protect life and property from effects of extremes in the water cycle. A major change in thinking about water science that goes beyond its physics to include its role in ecosystems and society is also required. Better water-cycle observations, especially on the continental and global scales, will be essential. Water-cycle predictions need to be readily available globally to reduce loss of life and property caused by water-related natural hazards. Building on the 2007 Earth Science Decadal Survey, NASA's Plan for a Climate-Centric Architecture for Earth Observations and Applications from Space , and the 2012 Chapman Conference on Remote Sensing of the Terrestrial Water Cycle, a workshop was held in April 2013 to gather wisdom and determine how to prepare for the next generation of water cycle missions in support of the second Earth Science Decadal Survey. This talk will present the outcomes of the workshop including the intersection between science questions, technology readiness and satellite design optimization. A series of next-generation water cycle mission working groups were proposed and white papers, designed to identify capacity gaps and inform NASA were developed. The workshop identified several visions for the next decade of water cycle satellite observations, and developed a roadmap and action plan for developing the foundation for these missions. Achieving this outcome will result in optimized community investments and better functionality of these future missions, and will help to foster broader range of scientists and professionals engaged in water cycle observation planning and development around the country, and the world.

Houser, P. R.

2013-12-01

359

Family Life Cycle Stages  

Microsoft Academic Search

Individual life stages happen within the context of family life. This article describes Betty Carter's and Monica McGoldrick's Family Life Cycle stages as a context for Eric Erikson's stages of psychosocial development, Daniel Levinson's Stages of a Man's Life, and Jean Piaget's stages of cognitive development. The author juxtaposes the tasks of each family life stage with the individual life

M. A. Armour

1995-01-01

360

Life Cycles of Stars  

NSDL National Science Digital Library

This Powerpoint presentation inroduces younger students to the life cycles of stars. Topics include stellar nurseries, types of stars, supernovae, the fates of stars of either high or low mass, and the creation of heavier elements by continued fusion of successively heavier elements.

361

Carbon Cycle Diagram  

NSDL National Science Digital Library

This diagram illustrates some of the most abundant stores of carbon and identifies some of the pathways in the carbon cycle along which carbon is transferred from one form to another. Long-term sinks of carbon are labelled in black; shorter-term fluxes are labelled in purple. Amounts are in billions of tons.

362

Ecosystem element cycling Introduction  

E-print Network

Ecosystem element cycling Introduction An ecosystem consists of all the biological organisms and the physical environments they occupy together within a defined area [1]. The actual boundaries of an ecosystem are generally defined by researchers studying the ecosystem, who are usually interested in understanding

Ickert-Bond, Steffi

363

LIFE CYCLE ANALYSIS  

EPA Science Inventory

Life cycle analysis, or LCA for short, is a term that has been used more and more over the past year to describe the cradle-to-grave environmental impacts of a product. he LCA is a way of looking at the environmental demands of a product holistically; that is, looking at,the reso...

364

LIFE-CYCLE ASSESSMENT  

EPA Science Inventory

Life Cycle Assessment, or LCA, is an environmental accounting and mangement approach that consider all the aspects of resource use and environmental releases associated with an industrial system from cradle-to-grave. Specifically, it is a holistic view of environmental interacti...

365

Carbon Cycle Game  

NSDL National Science Digital Library

In this interactive, regionally-relevant carbon cycle game, students are challenged to understand the role of carbon in global climate change. They imagine that they are carbon molecules and travel via different processes through carbon reservoirs on the Colorado Plateau (the Four Corners area of Arizona, Colorado, New Mexico and Utah). This game can be adapted to other regions.

Colorado Plateau Climate Science and Solutions Partnership

366

NOAA Water Cycle Game  

NSDL National Science Digital Library

The resource is a role-playing game in which students take on the role of a water molecule and travel through nine compartments of the water cycle to gain a better understanding for the true complexity of the movement of water.

367

Life Cycles of Animals  

NSDL National Science Digital Library

After a brief introduction, the page is divided into Places to go, People to see, Things to do, Teacher resources and a Bibliography. Each division has several links. For example the Places to go division has links to frog, ant, coral reef, and American bald eagle life cycles.

2010-01-01

368

The Science of Cycling  

ERIC Educational Resources Information Center

Children are engaged by finding out about science in the real world (Harlen, 2010). Many children will be cyclists or will have seen or heard about the success of British cyclists in the Olympics and the Tour de France. This makes cycling a good hook to draw children into learning science. It is also a good cross-curricular topic, with strong…

Crompton, Zoe; Daniels, Shelley

2014-01-01

369

The Solar Cycle  

NASA Technical Reports Server (NTRS)

Sunspots provided the first evidence for the 11-year cycle of solar activity and continue to provide key indicators of the level and nature of solar activity. Solar flares, prominence eruptions, and coronal mass ejections increase in frequency as the number of sunspots increases during the rising phase of the solar cycle. The total irradiance of the Sun and its irradiance in ultraviolet light and x-rays also increase as the sunspot number increases. On the other hand, the flux of galactic cosmic rays reaching Earth decreases as the sunspot number increases. These changes in the heliospheric environment produce significant effects on our environment. Our technological assets, in space, in the air, and on the ground, can be adversely affected by solar activity. Satellite drag, single-event upsets in electronic components, radio communication outages, power outages, and terrestrial climate can all be influenced by solar activity. In this lecture I will describe many of the significant characteristics of the solar cycle, their roots in solar magnetism, the mechanisms of the Sun's magnetic dynamo, and predictions for the amplitude and timing of next solar cycle.

Hathaway, D. H.

2007-01-01

370

The Geologic Nitrogen Cycle  

NASA Astrophysics Data System (ADS)

N2 is the dominant gas in Earth's atmosphere, and has been so through the majority of the planet's history. Originally thought to only be cycled in significant amounts through the biosphere, it is becoming increasingly clear that a large degree of geologic cycling can occur as well. N is present in crustal rocks at 10s to 100s of ppm and in the mantle at 1s to perhaps 10s of ppm. In light of new data, we present an Earth-system perspective of the modern N cycle, an updated N budget for the silicate Earth, and venture to explain the evolution of the N cycle over time. In an fashion similar to C, N has a fast, biologically mediated cycle and a slower cycle driven by plate tectonics. Bacteria fix N2 from the atmosphere into bioavailable forms. N is then cycled through the food chain, either by direct consumption of N-fixing bacteria, as NH4+ (the primary waste form), or NO3- (the most common inorganic species in the modern ocean). Some organic material settles as sediment on the ocean floor. In anoxic sediments, NH4+ dominates; due to similar ionic radii, it can readily substitute for K+ in mineral lattices, both in sedimentary rocks and in oceanic lithosphere. Once it enters a subduction zone, N may either be volatilized and returned to the atmosphere at arc volcanoes as N2 or N2O, sequestered into intrusive igneous rocks (as NH4+?), or subducted deep into the mantle, likely as NH4+. Mounting evidence indicates that a significant amount of N may be sequestered into the solid Earth, where it may remain for long periods (100s m.y.) before being returned to the atmosphere/biosphere by volcanism or weathering. The magnitude fluxes into the solid Earth and size of geologic N reservoirs are poorly constrained. The size of the N reservoirs contained in the solid Earth directly affects the evolution of Earth's atmosphere. It is possible that N now sequestered in the solid Earth was once in the atmosphere, which would have resulted in a higher atmospheric pressure, and therefore strengthened the greenhouse effect by pressure broadening the absorption of greenhouse gases. In addition,the behaviour of N is dependent on redox conditions in the ocean, which have not been constant over time.

Johnson, B. W.; Goldblatt, C.

2013-12-01

371

Westinghouse fuel cell combined cycle systems  

SciTech Connect

Efficiency (voltage) of the solid oxide fuel cell (SOFC) should increase with operating pressure, and a pressurized SOFC could function as the heat addition process in a Brayton cycle gas turbine (GT) engine. An overall cycle efficiency of 70% should be possible. In cogeneration, half of the waste heat from a PSOFC/GT should be able to be captured in process steam and hot water, leading to a fuel effectiveness of about 85%. In order to make the PSOFC/GT a commercial reality, satisfactory operation of the SOFC at elevated pressure must be verified, a pressurized SOFC generator module must be designed, built, and tested, and the combined cycle and parameters must be optimized. A prototype must also be demonstrated. This paper describes progress toward making the PSOFC/GT a reality.

Veyo, S.

1996-12-31

372

Scaling Population Cycles of Herbivores and Carnivores  

E-print Network

Periodicity in population dynamics is a fundamental issue. In addition to current species-specific analyses, allometry facilitates understanding of limit cycles amongst different species. So far, body-size regressions have been derived for the oscillation period of the population densities of warm-blooded species, in particular herbivores. Here, we extend the allometric analysis to other clades, allowing for a comparison between the obtained slopes and intercepts. The oscillation periods were derived from databases and original studies to cover a broad range of conditions and species. Then, values were related to specific body size by regression analysis. For different groups of herbivorous species, the oscillation period increased as a function of individual mass as a power law with exponents of 0.11-0.27. The intercepts of the resulting linear regressions indicated that cycle times for equally-sized species increased from homeotherms up to invertebrates. Overall, cycle times for predators did not scale to b...

Mulder, Christian

2010-01-01

373

Assessing Understanding of the Learning Cycle: The ULC  

NASA Astrophysics Data System (ADS)

An 18-item, multiple choice, 2-tiered instrument designed to measure understanding of the learning cycle (ULC) was developed and field-tested from the learning cycle test (LCT) of Odom and Settlage ( Journal of Science Teacher Education, 7, 123 142, 1996). All question sets of the LCT were modified to some degree and 5 new sets were added, resulting in the ULC. The ULC measures (a) understandings and misunderstandings of the learning cycle, (b) the learning cycle’s association with Piaget’s ( Biology and knowledge theory: An essay on the relations between organic regulations and cognitive processes, 1975) theory of mental functioning, and (c) applications of the learning cycle. The resulting ULC instrument was evaluated for internal consistency with Cronbach’s alpha, yielding a coefficient of .791.

Marek, Edmund A.; Maier, Steven J.; McCann, Florence

2008-08-01

374

Life Cycle of a Butterfly  

NSDL National Science Digital Library

We will learn the basic cycle of a butterfly's life, starting with an egg and ending as a butterfly. Choose one of the following web pages to visit and learn about the life cycle of a butterfly: This link shows real pictures- Butterfly Life Cycle -OR- This link shows cartoon pictures- Life Cycle (clip art images) Now that you have knowledge about the butterfly, Test what you have learned with this fun life cycle activity! Life Cycle Activity When caterpillars change to butterflies, this is ...

Integratingtechlauryn

2012-02-07

375

Protein tyrosine nitration in the cell cycle  

SciTech Connect

Highlights: {yields} Enrichment of 3-nitrotyrosine containing proteins from cells synchronized in different phases of the cell cycle. {yields} Identification of 76 tyrosine nitrated proteins that change expression during the cell cycle. {yields} Nineteen identified proteins were previously described as regulators of cell proliferation. -- Abstract: Nitration of tyrosine residues in proteins is associated with cell response to oxidative/nitrosative stress. Tyrosine nitration is relatively low abundant post-translational modification that may affect protein functions. Little is known about the extent of protein tyrosine nitration in cells during progression through the cell cycle. Here we report identification of proteins enriched for tyrosine nitration in cells synchronized in G0/G1, S or G2/M phases of the cell cycle. We identified 27 proteins in cells synchronized in G0/G1 phase, 37 proteins in S phase synchronized cells, and 12 proteins related to G2/M phase. Nineteen of the identified proteins were previously described as regulators of cell proliferation. Thus, our data indicate which tyrosine nitrated proteins may affect regulation of the cell cycle.

Jia, Min, E-mail: min.jia@ki.se [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden)] [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden); Mateoiu, Claudia; Souchelnytskyi, Serhiy [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden)] [Department of Oncology-Pathology, Karolinska Institutet, Stockholm (Sweden)

2011-09-23

376

A Survey and Synthesis of Solar Cycle Prediction Techniques  

NASA Technical Reports Server (NTRS)

A number of techniques for predicting solar activity on a solar cycle time scale are identified, described, and tested with historical data. Some techniques, e.g. regression and curve-fitting, work well as solar activity approaches maximum and provide a complete 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 the most 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+/-21 at the 95% level of confidence for the next cycle maximum. A mathematical function dependent upon the time of cycle initiation and the cycle amplitude then describes the level of solar activity for the next complete 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+/-20 at the 95% level of confidence for the next cycle maximum. The success of the geomagnetic precursors in predicting future solar activity suggests that solar magnetic phenomena at latitudes above the sunspot activity belts are linked to solar activity which occurs many years later in the lower latitudes.

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

1999-01-01

377

Rock Cycle Animations  

NSDL National Science Digital Library

Many people might know about the life cycle of a rock, but it can be a process that is hard to understand without a handy visual aid. Just such a series of aids can be found right here, courtesy of Mark Francek of Central Michigan University. These rock cycle animations display some of the most common rock-forming processes, including the crystallization of magma to form igneous rock, rock erosion to create sediment, and several others. That's not all, as visitors can also examine a comprehensive Flash animation which contains three separate movies, each of which looks at the formation of igneous rocks in environments that include a deep magma chamber and rocks forming from a pyroclastic flow. The site is rounded out by an interactive igneous rocks classification chart, arranged by texture and chemical composition.

378

Interactive Rock Cycle Animation  

NSDL National Science Digital Library

This highly simplified Flash animation displays some of the most common rock-forming processes. Embedded animations include crystallization of magma to form igneous rock, rock erosion to create sediment, transportation of sediment, deposition of sediment to create sedimentary rock, and creation of a metamorphic rock in a subduction zone. The neat feature of this animation is that each step in the sequence above is linked to other animations in the Exploring Earth collection, providing a fairly in depth exposure to the processes involved in the rock cycle. Caution students against the oversimplified linear pattern of igneous, sedimentary, and metamorphic rock formation. In reality, there are many interconnections in the cycle with, for example, sedimentary rocks being eroded and becoming transformed to a different sedimentary rock type without being metamorphosed or, as another example, igneous rocks never being reduced to sediment, and instead directly evolving to metamorphic rocks. The animation can be paused and rewound to stress important points.

Armstrong, Lenni; Earth, Exploring

379

The Carbon Cycle  

NASA Astrophysics Data System (ADS)

Reducing carbon dioxide (CO2) emissions is imperative to stabilizing our future climate. Our ability to reduce these emissions combined with an understanding of how much fossil-fuel-derived CO2 the oceans and plants can absorb is central to mitigating climate change. In The Carbon Cycle, leading scientists examine how atmospheric carbon dioxide concentrations have changed in the past and how this may affect the concentrations in the future. They look at the carbon budget and the "missing sink" for carbon dioxide. They offer approaches to modeling the carbon cycle, providing mathematical tools for predicting future levels of carbon dioxide. This comprehensive text incorporates findings from the recent IPCC reports. New insights, and a convergence of ideas and views across several disciplines make this book an important contribution to the global change literature.

Wigley, T. M. L.; Schimel, D. S.

2005-08-01

380

Review Article Hepatic response to aluminum toxicity: Dyslipidemia and  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . 2232 Anaerobic metabolism: Al promotes anaerobic respiration . . . . . . . . . . . . . . . . . . . . . . . . . . 2232 Al disrupts the tricarboxylic acid (TCA) cycle and aerobic respiration

Appanna, Vasu

381

Comparison of trilateral cycles and organic Rankine cycles  

Microsoft Academic Search

A comparison of optimized trilateral cycle (TLC) - systems with water as working fluid and optimized organic Rankine cycle (ORC) – systems with pure organic working fluids is presented. The study includes the heat transfer to and from the cycles. The TLC - systems were optimized by the selection of the maximum water temperature, the ORC - systems by the

Johann Fischer

2011-01-01

382

Phosphatidylcholine and the CDP-Choline Cycle  

PubMed Central

The CDP-choline pathway of phosphatidylcholine (PtdCho) biosynthesis was first described more than 50 years ago. Investigation of the CDP-choline pathway in yeast provides a basis for understanding the CDP-choline pathway in mammals. PtdCho is considered as an intermediate in a cycle of synthesis and degradation, and the activity of a CDP-choline cycle is linked to subcellular membrane lipid movement. The components of the mammalian CDP-choline pathway include choline transport, choline kinase, phosphocholine cytidylyltransferase, and choline phosphotransferase activities. The protein isoforms and biochemical mechanisms of regulation of the pathway enzymes are related to their cell and tissue-specific functions. Regulated PtdCho turnover mediated by phospholipases or neuropathy target esterase participates in the mammalian CDP-choline cycle. Knockout mouse models define the biological functions of the CDP-choline cycle in mammalian cells and tissues. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:23010477

Fagone, Paolo; Jackowski, Suzanne

2012-01-01

383

Rock Cycle Stories  

NSDL National Science Digital Library

In this exercise, sudents write a series of three stories that explain and/or illustrate rock-forming processes. As an alternative, they may write a single story that addresses the rock cycle. Describing these processes at a level appropriate for their target audience (second graders) requires an adequate understanding of the geologic processes involved and can reveal problems or misconceptions in the students' ideas of how rocks are formed. Teacher's notes and rubrics for teacher and peer review are provided.

Ebert, James

384

Cave Formation: Biogeochemical Cycles  

NSDL National Science Digital Library

This video explores the role of biogeochemical cycles in the formation of caves. It discusses a radical new theory that identifies sulfuric acid as a cave-forming agent. The video, adapted from a NOVA broadcast, identifies the source of the sulfuric acid, which, unlike carbonic acid, the typical cave-forming agent, does not readily form in nature. The segment is 5 minutes and forty seconds in length.

385

Carbon Cycle Poster  

NSDL National Science Digital Library

In this activity, learners gain knowledge about how carbon moves through all four of the Earth’s major spheres (biosphere, hydrosphere, atmosphere, and lithosphere), and understand how humans influence the carbon cycle and contribute to global climate change. Learners work in groups to create a diagram to show how the Earth's major spheres are connected by diffusion, respiration, burial, and weathering. This detailed lesson plan includes key vocabulary words, discussion questions, resources for educators, and is standards-based.

California Academy of Sciences

2008-01-01

386

The carbon dioxide cycle  

USGS Publications Warehouse

The seasonal CO2 cycle on Mars refers to the exchange of carbon dioxide between dry ice in the seasonal polar caps and gaseous carbon dioxide in the atmosphere. This review focuses on breakthroughs in understanding the process involving seasonal carbon dioxide phase changes that have occurred as a result of observations by Mars Global Surveyor. ?? 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

James, P.B.; Hansen, G.B.; Titus, T.N.

2005-01-01

387

Stirling cycle engine  

DOEpatents

In a Stirling cycle engine having a plurality of working gas charges separated by pistons reciprocating in cylinders, the total gas content is minimized and the mean pressure equalization among the serial cylinders is improved by using two piston rings axially spaced at least as much as the piston stroke and by providing a duct in the cylinder wall opening in the space between the two piston rings and leading to a source of minimum or maximum working gas pressure.

Lundholm, Gunnar (Lund, SE)

1983-01-01

388

Species' Life Cycles  

NSDL National Science Digital Library

The National Wildlife Federation (NWF) provides these colorful pages summarizing different stages of several species's life cycles. Focusing on the interconnected and fragile nature of existence, this site features a half dozen species: Karner Blue Butterfly, Dwarf Wedgemussel, Chinook Salmon, Indiana Bat, Grizzly Bear, and Mauna Kea Silversword. This could serve as a fine supplement for introductory courses on basic ecology, population biology, conservation biology, or wildlife management.

389

Gondwanaland's seasonal cycle  

NASA Technical Reports Server (NTRS)

A two-dimensional energy balance climate model has been used to simulate the seasonal temperature cycle on a supercontinent-sized land mass. Experiments with idealized and realistic geography indicate that the land-sea configuration in high latitudes exerts a strong influence on the magnitude of summer warming. These simulations provide significant insight into the evolution of climate during the Palaeozoic, and raise questions about the presumed pre-eminent role of carbon dioxide in explaining long-term climate change.

Crowley, Thomas J.; Short, David A.; Mengel, John G.

1987-01-01

390

Rock Cycle: Earth's Autobiography  

NSDL National Science Digital Library

This Science Object is the fourth of four Science Objects in the Rocks SciPack. It investigates how geologists have used rocks to help determine the approximate age of the Earth and provide a timeline of how the Earth's surface and environments have changed over time. Scientists have tools to estimate the ages of rock and the overall time scale of the rock cycle. Some processes happen quickly and some happen slowly, but the oldest rocks indicate that the rock cycle has been recycling Earth's material continuously for roughly 4 billion years. The same processes have been at work throughout Earth's history, and therefore scientists can use the present to interpret the past. Observations of rock (textures, minerals, and fossils found within it) provides evidence of the environment and processes through which it formed, including the pressures, temperatures, and forces that created it.Learning Outcomes:� 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.

National Science Teachers Association (NSTA)

2006-11-01

391

External Resource: Rock Cycle Animation  

NSDL National Science Digital Library

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. Topics include: rock cycle, magma chamber, magma, igneous rock, sedimentary rock, erosio

1900-01-01

392

Rapid Cycling and Its Treatment  

MedlinePLUS

... someone with bipolar disorder experiences one or two cycles a year, with manic episodes generally occurring in ... sound as if the episodes occur in regular cycles, episodes actually often follow a random pattern. Some ...

393

Titan's methane cycle  

NASA Astrophysics Data System (ADS)

Methane is key to sustaining Titan's thick nitrogen atmosphere. However, methane is destroyed and converted to heavier hydrocarbons irreversibly on a relatively short timescale of approximately 10-100 million years. Without the warming provided by CH 4-generated hydrocarbon hazes in the stratosphere and the pressure induced opacity in the infrared, particularly by CH 4-N 2 and H 2-N 2 collisions in the troposphere, the atmosphere could be gradually reduced to as low as tens of millibar pressure. An understanding of the source-sink cycle of methane is thus crucial to the evolutionary history of Titan and its atmosphere. In this paper we propose that a complex photochemical-meteorological-hydrogeochemical cycle of methane operates on Titan. We further suggest that although photochemistry leads to the loss of methane from the atmosphere, conversion to a global ocean of ethane is unlikely. The behavior of methane in the troposphere and the surface, as measured by the Cassini-Huygens gas chromatograph mass spectrometer, together with evidence of cryovolcanism reported by the Cassini visual and infrared mapping spectrometer, represents a "methalogical" cycle on Titan, somewhat akin to the hydrological cycle on Earth. In the absence of net loss to the interior, it would represent a closed cycle. However, a source is still needed to replenish the methane lost to photolysis. A hydrogeochemical source deep in the interior of Titan holds promise. It is well known that in serpentinization, hydration of ultramafic silicates in terrestrial oceans produces H 2(aq), whose reaction with carbon grains or carbon dioxide in the crustal pores produces methane gas. Appropriate geological, thermal, and pressure conditions could have existed in and below Titan's purported water-ammonia ocean for "low-temperature" serpentinization to occur in Titan's accretionary heating phase. On the other hand, impacts could trigger the process at high temperatures. In either instance, storage of methane as a stable clathrate-hydrate in Titan's interior for later release to the atmosphere is quite plausible. There is also some likelihood that the production of methane on Titan by serpentinization is a gradual and continuous on-going process.

Atreya, Sushil K.; Adams, Elena Y.; Niemann, Hasso B.; Demick-Montelara, Jaime E.; Owen, Tobias C.; Fulchignoni, Marcello; Ferri, Francesca; Wilson, Eric H.

2006-10-01

394

The Life Cycle of Plants  

NSDL National Science Digital Library

What is the whole process of the plant life cycle? 1) You will need to open the Flow Chart. Flow Chart 2) Be sure to print out your own Flow Chart so you can record your information. 3) Look at the chart of the Life Cycle and print out your own copy. Chart showing the steps of the life cycle 4) Record each step of the Plant Life Cycle in your Flow Chart starting ...

Ms. Kingsford

2010-11-04

395

Internal cycle modeling and environmental assessment of multiple cycle consumer products  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Dynamic flow models are presented for remanufactured, reused or recycled products. Black-Right-Pointing-Pointer Early loss and stochastic return are included for fast and slow cycling products. Black-Right-Pointing-Pointer The reuse-to-input flow ratio (Internal Cycle Factor, ICF) is determined. Black-Right-Pointing-Pointer The cycle rate, which is increasing with the ICF, monitors eco-performance. Black-Right-Pointing-Pointer Early internal cycle losses diminish the ICF, the cycle rate and performance. - Abstract: Dynamic annual flow models incorporating consumer discard and usage loss and featuring deterministic and stochastic end-of-cycle (EOC) return by the consumer are developed for reused or remanufactured products (multiple cycle products, MCPs), including fast and slow cycling, short and long-lived products. It is shown that internal flows (reuse and overall consumption) increase proportionally to the dimensionless internal cycle factor (ICF) which is related to environmental impact reduction factors. The combined reuse/recycle (or cycle) rate is shown capable for shortcut, albeit effective, monitoring of environmental performance in terms of waste production, virgin material extraction and manufacturing impacts of all MCPs, a task, which physical variables (lifetime, cycling frequency, mean or total number of return trips) and conventional rates, via which environmental policy has been officially implemented (e.g. recycling rate) cannot accomplish. The cycle rate is shown to be an increasing (hyperbolic) function of ICF. The impact of the stochastic EOC return characteristics on total reuse and consumption flows, as well as on eco-performance, is assessed: symmetric EOC return has a small, positive effect on performance compared to deterministic, while early shifted EOC return is more beneficial. In order to be efficient, environmental policy should set higher minimum reuse targets for higher trippage MCPs. The results may serve for monitoring, flow accounting and comparative eco-assessment of MCPs. They may be useful in identifying reachable and efficient reuse/recycle targets for consumer products and in planning return via appropriate labelling and digital coding for enhancing environmental performance, while satisfying consumer demand.

Tsiliyannis, C.A., E-mail: anion@otenet.gr [ANION Environmental Ltd., 26 Lykoudi Str., Athens 11141 (Greece)

2012-01-15

396

On the Importance of Cycle Minimum in Sunspot Cycle Prediction  

NASA Technical Reports Server (NTRS)

The characteristics of the minima between sunspot cycles are found to provide important information for predicting the amplitude and timing of the following cycle. For example, the time of the occurrence of sunspot minimum sets the length of the previous cycle, which is correlated by the amplitude-period effect to the amplitude of the next cycle, with cycles of shorter (longer) than average length usually being followed by cycles of larger (smaller) than average size (true for 16 of 21 sunspot cycles). Likewise, the size of the minimum at cycle onset is correlated with the size of the cycle's maximum amplitude, with cycles of larger (smaller) than average size minima usually being associated with larger (smaller) than average size maxima (true for 16 of 22 sunspot cycles). Also, it was found that the size of the previous cycle's minimum and maximum relates to the size of the following cycle's minimum and maximum with an even-odd cycle number dependency. The latter effect suggests that cycle 23 will have a minimum and maximum amplitude probably larger than average in size (in particular, minimum smoothed sunspot number Rm = 12.3 +/- 7.5 and maximum smoothed sunspot number RM = 198.8 +/- 36.5, at the 95-percent level of confidence), further suggesting (by the Waldmeier effect) that it will have a faster than average rise to maximum (fast-rising cycles have ascent durations of about 41 +/- 7 months). Thus, if, as expected, onset for cycle 23 will be December 1996 +/- 3 months, based on smoothed sunspot number, then the length of cycle 22 will be about 123 +/- 3 months, inferring that it is a short-period cycle and that cycle 23 maximum amplitude probably will be larger than average in size (from the amplitude-period effect), having an RM of about 133 +/- 39 (based on the usual +/- 30 percent spread that has been seen between observed and predicted values), with maximum amplitude occurrence likely sometime between July 1999 and October 2000.

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

1996-01-01

397

Episodic Tremor and Slip: Cycles Within Cycles  

NASA Astrophysics Data System (ADS)

Episodic tremor and slip (ETS) events, each with geodetically determined moment magnitudes in the mid-6 range, repeat about every 15 months under the Olympic Peninsula/southern Vancouver Island region. We have automatically searched for non-volcanic tremor in all 5-minute time windows both during the past five ETS events and during the two inter-ETS periods from February, 2007 through April, 2008 and June 2008 through April 2009. Inter-ETS tremor was detected in 5000 windows, which overlap by 50%, so tremor was seen 2% of the time. The catalog of 5-minute tremor locations cluster in time and space into groups we call tremor swarms, revealing 50 inter-ETS tremor swarms. The number of hours of tremor per swarm ranged from about 1 to 68, totaling 374 hours. The inter-ETS tremor swarms generally locate along the downdip side of the major ETS events, and account for approximately 45% of the time that tremor has been detected during the last two entire ETS cycles. Many of the inter-ETS events are near-carbon copies in duration, spatial extent and propagation direction, as is seen for the larger 15-month-interval events. These 50 inter-ETS swarms plus two major ETS episodes follow a power law relationship such that the number of swarms, N, exceeding duration ? is given by N ˜ ?-0.7. If we assume that seismic moment is proportional to ? as proposed by Ide et al. [Nature, 2007], we find that the tremor swarms follow a standard Gutenberg-Richter logarithmic frequency-magnitude relation, N ˜ 10-bMw, with b = 1.0, which lies in the range for normal earthquake catalogs. Furthermore, the major ETS events fall on the curve defined by the inter-ETS swarms, suggesting that the inter-ETS swarms are just smaller versions of the major 15-month ETS events. Only the largest events coincide with geodetically observed slip, suggesting that current geodetic observations may be missing nearly half of the total slip. Finally, crude estimates of the spatial dimensions of tremor swarms L suggest that L ˜ ?1/n where n is between 2 and 3. A value of 2 is consistent with slip propagation rates being controlled by a diffusional process. In contrast, n is observed to be about 1 for normal earthquakes because rupture generally propagates at a velocity close to the shear-wave speed.

Creager, K. C.; Wech, A.; Vidale, J. E.

2009-12-01

398

Edinburgh Research Explorer Money Cycles  

E-print Network

Edinburgh Research Explorer Money Cycles Citation for published version: Clausen, A & Strub, C 2014 'Money Cycles' Edinburgh School of Economics Discussion Paper Series. Link: Link to publication record date: 11. Dec. 2014 #12;Edinburgh School of Economics Discussion Paper Series Number 249 Money Cycles

Millar, Andrew J.

399

Oxaloacetate-to-malate conversion by mineral photoelectrochemistry  

E-print Network

by the reductive tricarboxylic acid (rTCA) cycle are possibly a biosynthetic core of initial life, although severalTCA cycle has been hypothesized as older than the origin of life, implying that it operated under non received much attention in regard to the origin and evolution of life (Aoshima 2007). The rTCA cycle

400

Fictitious Supercontinent Cycles  

NASA Astrophysics Data System (ADS)

"Supercontinent cycles" or "Wilson cycles" is the idea that before Pangaea there were a series of supercontinents that each formed and then broke apart and separated before colliding again, re-aggregating, and suturing into a new supercontinent in a continuing sequence. I suggest that "supercontinent cycles" are artificial constructs, like planetary orbit epicycles, attempts to describe geological phenomena within the framework of problematic paradigms, namely, planetesimal Earth formation and plate tectonics' mantle convection. The so-called 'standard model of solar system formation' is problematic as it would lead to insufficiently massive planetary cores and necessitates additional ad hoc hypotheses such as the 'frost line' between Mars and Jupiter to explain planetary differences and whole-planet melting to explain core formation from essentially undifferentiated matter. The assumption of mantle convection is crucial for plate tectonics, not only for seafloor spreading, but also for continental movement; continent masses are assumed to ride atop convection cells. In plate tectonics, plate collisions are thought to be the sole mechanism for fold-mountain formation. Indeed, the occurrence of mountain chains characterized by folding which significantly predate the breakup of Pangaea is the primary basis for assuming the existence of supercontinent cycles with their respective periods of ancient mountain-forming plate collisions. Mantle convection is physically impossible. Rayleigh Number justification has been misapplied. The mantle bottom is too dense to float to the surface by thermal expansion. Sometimes attempts are made to obviate the 'bottom heavy' prohibition by adopting the tacit assumption that the mantle behaves as an ideal gas with no viscous losses, i.e., 'adiabatic'. But the mantle is a solid that does not behave as an ideal gas as evidenced by earthquakes occurring at depths as great as 660 km. Absent mantle convection, plate tectonics is not valid and there is no motive force for driving supercontinent cycles. The reasonable conclusion one must draw, as in the case of epicycles, is there must exist a new and fundamentally different geoscience paradigm which obviates the problems inherent in plate tectonics and in planetesimal Earth formation and yet better explains geological features. I have disclosed a new indivisible geoscience paradigm, called Whole-Earth Decompression Dynamics (WEDD), that begins with and is the consequence of our planet's early formation as a Jupiter-like gas giant and which permits deduction of: (1) Earth's internal composition and highly-reduced oxidation state; (2) Core formation without whole-planet melting; (3) Powerful new internal energy sources, protoplanetary energy of compression and georeactor nuclear fission energy; (4) Mechanism for heat emplacement at the base of the crust; (5) Georeactor geomagnetic field generation; (6) Decompression-driven geodynamics that accounts for the myriad of observations attributed to plate tectonics without requiring physically-impossible mantle convection, and; (7) A mechanism for fold-mountain formation that does not necessarily require plate collision. The latter obviates the necessity to assume supercontinent cycles. The fundamental basis of geodynamics is this: In response to decompression-driven Earth volume increases, cracks form to increase surface area and mountain ranges characterized by folding form to accommodate changes in curvature. Resources at NuclearPlanet.com .

Marvin Herndon, J.

2014-05-01

401

GEOSS Water Cycle Integrator  

NASA Astrophysics Data System (ADS)

It is critically important to recognize and co-manage the fundamental linkages across the water-dependent domains; land use, including deforestation; ecosystem services; and food-, energy- and health-securities. Sharing coordinated, comprehensive and sustained observations and information for sound decision-making is a first step; however, to take full advantage of these opportunities, we need to develop an effective collaboration mechanism for working together across different disciplines, sectors and agencies, and thereby gain a holistic view of the continuity between environmentally sustainable development, climate change adaptation and enhanced resilience. To promote effective multi-sectoral, interdisciplinary collaboration based on coordinated and integrated efforts, the Global Earth Observation System of Systems (GEOSS) is now developing a "GEOSS Water Cycle Integrator (WCI)", which integrates "Earth observations", "modeling", "data and information", "management systems" and "education systems". GEOSS/WCI sets up "work benches" by which partners can share data, information and applications in an interoperable way, exchange knowledge and experiences, deepen mutual understanding and work together effectively to ultimately respond to issues of both mitigation and adaptation. (A work bench is a virtual geographical or phenomenological space where experts and managers collaborate to use information to address a problem within that space). GEOSS/WCI enhances the coordination of efforts to strengthen individual, institutional and infrastructure capacities, especially for effective interdisciplinary coordination and integration. GEO has established the GEOSS Asian Water Cycle Initiative (AWCI) and GEOSS African Water Cycle Coordination Initiative (AfWCCI). Through regional, inter-disciplinary, multi-sectoral integration and inter-agency coordination in Asia and Africa, GEOSS/WCI is now leading to effective actions and public awareness in support of water security and sustainable development.

Koike, T.; Lawford, R. G.; Cripe, D.

2012-12-01

402

GEOSS Water Cycle Integrator  

NASA Astrophysics Data System (ADS)

It is critically important to recognize and co-manage the fundamental linkages across the water-dependent domains; land use, including deforestation; ecosystem services; and food-, energy- and health-securities. Sharing coordinated, comprehensive and sustained observations and information for sound decision-making is a first step; however, to take full advantage of these opportunities, we need to develop an effective collaboration mechanism for working together across different disciplines, sectors and agencies, and thereby gain a holistic view of the continuity between environmentally sustainable development, climate change adaptation and enhanced resilience. To promote effective multi-sectoral, interdisciplinary collaboration based on coordinated and integrated efforts, the intergovernmental Group on Earth Observations (GEO) is implementing the Global Earth Observation System of Systems (GEOSS). A component of GEOSS now under development is the "GEOSS Water Cycle Integrator (WCI)", which integrates Earth observations, modeling, data and information, management systems and education systems. GEOSS/WCI sets up "work benches" by which partners can share data, information and applications in an interoperable way, exchange knowledge and experiences, deepen mutual understanding and work together effectively to ultimately respond to issues of both mitigation and adaptation. (A work bench is a virtual geographical or phenomenological space where experts and managers collaborate to use information to address a problem within that space). GEOSS/WCI enhances the coordination of efforts to strengthen individual, institutional and infrastructure capacities, especially for effective interdisciplinary coordination and integration. GEO has established the GEOSS Asian Water Cycle Initiative (AWCI) and GEOSS African Water Cycle Coordination Initiative (AfWCCI). Through regional, inter-disciplinary, multi-sectoral integration and inter-agency coordination in Asia and Africa, GEOSS/WCI is now leading to effective actions and public awareness in support of water security and sustainable development.

Koike, Toshio; Lawford, Richard; Cripe, Douglas

2013-04-01

403

The Global Phosphorus Cycle  

NASA Astrophysics Data System (ADS)

Phosphorus is an essential nutrient for all life forms. It is a key player in fundamental biochemical reactions (Westheimer, 1987) involving genetic material (DNA, RNA) and energy transfer (ATP), and in structural support of organisms provided by membranes (phospholipids) and bone (the biomineral hydroxyapatite). Photosynthetic organisms utilize dissolved phosphorus, carbon, and other essential nutrients to build their tissues using energy from the Sun. Biological productivity is contingent upon the availability of phosphorus to these simple organisms that constitute the base of the food web in both terrestrial and aquatic systems. (For reviews of P-utilization, P-biochemicals, and pathways in aquatic plants, see Fogg (1973), Bieleski and Ferguson (1983), and Cembella et al. (1984a, 1984b).)Phosphorus locked up in bedrock, soils, and sediments is not directly available to organisms. Conversion of unavailable forms to dissolved orthophosphate, which can be directly assimilated, occurs through geochemical and biochemical reactions at various stages in the global phosphorus cycle. Production of biomass fueled by P-bioavailability results in the deposition of organic matter in soils and sediments, where it acts as a source of fuel and nutrients to microbial communities. Microbial activity in soils and sediments, in turn, strongly influences the concentration and chemical form of phosphorus incorporated into the geological record.The global phosphorus cycle has four major components: (i) tectonic uplift and exposure of phosphorus-bearing rocks to the forces of weathering; (ii) physical erosion and chemical weathering of rocks producing soils and providing dissolved and particulate phosphorus to rivers; (iii) riverine transport of phosphorus to lakes and the ocean; and (iv) sedimentation of phosphorus associated with organic and mineral matter and burial in sediments (Figure 1). The cycle begins anew with uplift of sediments into the weathering regime.

Ruttenberg, K. C.

2003-12-01

404

Thermodynamic cycle analysis  

NASA Technical Reports Server (NTRS)

An analysis was made of Rankine cycle efficiency in nuclear power plants with and without reheat capabilities. In addition, temperatures and pressures at certain selected locations were carried out to optimize plant efficiency. It was determined that plant efficiency without reheat was 39.03%, with reheat, a maximum efficiency of 4.44% was obtained at a pressure of 435.12 psia. Data also indicate efficiency appears to increase for pressures greater than 720 psia. However, higher pressures cannot be used because calculations indicate these pressure reheat temperatures exceed 1650 R, which is not allowed due to material limitations.

1976-01-01

405

Rock Cycle Roundabout  

NSDL National Science Digital Library

In this activity, learners will learn how igneous rock, metamorphic rock, and sedimentary rock are formed as part of the rock cycle and that the same forces that produce/change rocks also produce/change landforms. They will learn this by playing a game where one player must describe a type of rock (that is chosen by random card selection) to another player who then must guess what type of rock that is. Then, there may be a discussion of geologic time and learners can create a timeline model based on the sequence of rock types that were chosen in the game.

Sciences, California A.

2010-01-01

406

Natural Cycles, Gases  

NASA Technical Reports Server (NTRS)

The major gaseous components of the exhaust of stratospheric aircraft are expected to be the products of combustion (CO2 and H2O), odd nitrogen (NO, NO2 HNO3), and products indicating combustion inefficiencies (CO and total unburned hydrocarbons). The species distributions are produced by a balance of photochemical and transport processes. A necessary element in evaluating the impact of aircraft exhaust on the lower stratospheric composition is to place the aircraft emissions in perspective within the natural cycles of stratospheric species. Following are a description of mass transport in the lower stratosphere and a discussion of the natural behavior of the major gaseous components of the stratospheric aircraft exhaust.

Douglass, Anne R.; Jackman, Charles H.; Rood, R. B.; Aikin, A. C.; Stolarski, R. S.; Mccormick, M. P.; Fahey, David W.

1992-01-01

407

Geomicrobiological cycling of antimony  

NASA Astrophysics Data System (ADS)

Microbiologically catalyzed oxidation and reduction of toxic metalloids (e.g., As, Se, and Te) generally proceeds much faster than corresponding abiotic reactions. These microbial transformations constitute biogeochemical cycles that control chemical speciation and environmental behavior of metalloids in aqueous environments. Particular progress has been made over the past two decades in documenting microbiological biotransformations of As, which include anaerobic respiratory reduction of As(V) to As(III), oxidation of As(III) to As(V) linked to chemoautotrophy or photoautotrophy, and cellular detoxification pathways. By contrast, microbial interactions with Sb, As's group 15 neighbor and a toxic element of emerging global concern, are poorly understood. Our work with sediment microcosms, enrichment cultures, and bacterial isolates suggests that prokaryotic metabolisms may be similarly important to environmental Sb cycling. Enrichment cultures and isolates from a Sb-contaminated mine site in Idaho exhibited Sb(V)-dependent heterotrophic respiration under anaerobic conditions and Sb(III)-dependent autotrophic growth in the presence of air. Live, anoxic cultures reduced 2 mM Sb(V) to Sb(III) within 5 d, while no activity occurred in killed controls. Sb(V) reduction was stimulated by lactate or acetate and was quantitatively coupled to the oxidation of lactate. The oxidation of radiolabeled 14C-acetate (monitored by GC-GPC) demonstrated Sb(V)-dependent oxidation to 14CO2, suggesting a dissimilatory process. Sb(V) dependent growth in cultures was demonstrated by direct counting. Microbiological reduction of Sb(V) also occurred in anerobic sediment microcosms from an uncontaminated suburban lake, but did not appear to be linked to growth and is interpreted as a mechanism of biological detoxification. Aerobic microcosms and cultures from the Idaho mine oxidized 2 mM Sb(III) to Sb(V) within 7 d and coupled this reaction to cell growth quantified by direct counting. An anoxygenic photosynthetic community of purple sulfur bacteria from Pyramid Lake, NV, however, that was capable of growth via anoxygenic photosynthesis using As(III) as an electron donor was not capable of similar growth using Sb(III). These results suggest that geomicrobiological Sb cycling is an important influence on the environmental speciation and behavior of Sb, and portend the presence of a global biogeochemical Sb cycle that is analogous to but distinct from that for As.

Kulp, T. R.; Terry, L.; Dovick, M. A.; Braiotta, F.

2013-12-01

408

Quantum thermodynamic cooling cycle  

NASA Astrophysics Data System (ADS)

The quantum-mechanical and thermodynamic properties of a three-level molecular cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force-the quantum analog of classical absorption chillers. The dependence of the maximum attainable cooling rate on temperature, at ultralow temperatures, is determined and shown to respect the recently established fundamental bound based on the second and third laws of thermodynamics.

Palao, José P.; Kosloff, Ronnie; Gordon, Jeffrey M.

2001-11-01

409

Geothermal Life Cycle Calculator  

DOE Data Explorer

This calculator is a handy tool for interested parties to estimate two key life cycle metrics, fossil energy consumption (Etot) and greenhouse gas emission (ghgtot) ratios, for geothermal electric power production. It is based solely on data developed by Argonne National Laboratory for DOE’s Geothermal Technologies office. The calculator permits the user to explore the impact of a range of key geothermal power production parameters, including plant capacity, lifetime, capacity factor, geothermal technology, well numbers and depths, field exploration, and others on the two metrics just mentioned. Estimates of variations in the results are also available to the user.

Sullivan, John

410

Geothermal Life Cycle Calculator  

SciTech Connect

This calculator is a handy tool for interested parties to estimate two key life cycle metrics, fossil energy consumption (Etot) and greenhouse gas emission (ghgtot) ratios, for geothermal electric power production. It is based solely on data developed by Argonne National Laboratory for DOE’s Geothermal Technologies office. The calculator permits the user to explore the impact of a range of key geothermal power production parameters, including plant capacity, lifetime, capacity factor, geothermal technology, well numbers and depths, field exploration, and others on the two metrics just mentioned. Estimates of variations in the results are also available to the user.

Sullivan, John

2014-03-11

411

Cycling Joule Thomson refrigerator  

NASA Astrophysics Data System (ADS)

A symmetrical adsorption pump/compressor system having a pair of mirror image legs and a Joule Thomson expander, or valve, interposed between the legs thereof for providing a, efficient refrigeration cycle is described. The system further includes a plurality of gas operational heat switches adapted selectively to transfer heat from a thermal load and to transfer or discharge heat through a heat projector, such as a radiator or the like. The heat switches comprise heat pressurizable chambers adapted for alternate pressurization in response to adsorption and desorption of a pressurizing gas confined therein.

Tward, E.

1983-01-01

412

Genome-wide transcription map of an archaeal cell cycle  

PubMed Central

Relative RNA abundance was measured at different cell-cycle stages in synchronized cultures of the hyperthermophilic archaeon Sulfolobus acidocaldarius. Cyclic induction was observed for >160 genes, demonstrating central roles for transcriptional regulation and cell-cycle-specific gene expression in archaeal cell-cycle progression. Many replication genes were induced in a cell-cycle-specific manner, and novel replisome components are likely to be among the genes of unknown function with similar induction patterns. Candidate genes for the unknown genome segregation and cell division machineries were also identified, as well as seven transcription factors likely to be involved in cell-cycle control. Two serine-threonine protein kinases showed distinct cell-cycle-specific induction, suggesting regulation of the archaeal cell cycle also through protein modification. Two candidate recognition elements, CCR boxes, for transcription factors in control of cell-cycle regulons were identified among gene sets with similar induction kinetics. The results allow detailed characterization of the genome segregation, division, and replication processes and may, because of the extensive homologies between the archaeal and eukaryotic information machineries, also be applicable to core features of the eukaryotic cell cycle. PMID:17307872

Lundgren, Magnus; Bernander, Rolf

2007-01-01

413

Interactives: The Rock Cycle  

NSDL National Science Digital Library

How much do you know about rocks? Well, if you are a bit unsure about distinguishing an igneous rock from a sedimentary rock you'll certainly be on solid ground after taking a tour through this feature created by Annenberg Media. Visitors can make their way through graphically-enhanced sections that include "Types of Rocks", "How Rocks Change", and "The Rock Cycle Diagram". In the "Types of Rocks" area visitors will learn about the basic types of rocks and they can even check out a handy chart that will give them some of the finer points of rock identification. The "How Rocks Change" area provides a basic overview of the processes involved with rock creation and transformation through a heady blend of Flash animations and straight-forward prose. Finally, the "Rock Cycle Diagram" provides an illustration of rock transformation over time. This site will be quite useful to educators and anyone who has peered at a rock and wondered: "How did you come to be?"

2008-04-11

414

Interactives: The Rock Cycle  

NSDL National Science Digital Library

How much do you know about rocks? Well, if you are a bit unsure about distinguishing an igneous rock from a sedimentary rock you'll certainly be on solid ground after taking a tour through this feature created by Annenberg Media. Visitors can make their way through graphically-enhanced sections that include "Types of Rocks", "How Rocks Change", and "The Rock Cycle Diagram". In the "Types of Rocks" area visitors will learn about the basic types of rocks and they can even check out a handy chart that will give them some of the finer points of rock identification. The "How Rocks Change" area provides a basic overview of the processes involved with rock creation and transformation through a heady blend of Flash animations and straight-forward prose. Finally, the "Rock Cycle Diagram" provides an illustration of rock transformation over time. This site will be quite useful to educators and anyone who has peered at a rock and wondered: "How did you come to be?"

415

The Contemporary Carbon Cycle  

NASA Astrophysics Data System (ADS)

The global carbon cycle refers to the exchanges of carbon within and between four major reservoirs: the atmosphere, the oceans, land, and fossil fuels. Carbon may be transferred from one reservoir to another in seconds (e.g., the fixation of atmospheric CO2 into sugar through photosynthesis) or over millennia (e.g., the accumulation of fossil carbon (coal, oil, gas) through deposition and diagenesis of organic matter). This chapter emphasizes the exchanges that are important over years to decades and includes those occurring over the scale of months to a few centuries. The focus will be on the years 1980-2000 but our considerations will broadly include the years ˜1850-2100. Chapter 8.09, deals with longer-term processes that involve rates of carbon exchange that are small on an annual timescale (weathering, vulcanism, sedimentation, and diagenesis).The carbon cycle is important for at least three reasons. First, carbon forms the structure of all life on the planet, making up ˜50% of the dry weight of living things. Second, the cycling of carbon approximates the flows of energy around the Earth, the metabolism of natural, human, and industrial systems. Plants transform radiant energy into chemical energy in the form of sugars, starches, and other forms of organic matter; this energy, whether in living organisms or dead organic matter, supports food chains in natural ecosystems as well as human ecosystems, not the least of which are industrial societies habituated (addicted?) to fossil forms of energy for heating, transportation, and generation of electricity. The increased use of fossil fuels has led to a third reason for interest in the carbon cycle. Carbon, in the form of carbon dioxide (CO2) and methane (CH4), forms two of the most important greenhouse gases. These gases contribute to a natural greenhouse effect that has kept the planet warm enough to evolve and support life (without the greenhouse effect the Earth's average temperature would be -33°C). Additions of greenhouse gases to the atmosphere from industrial activity, however, are increasing the concentrations of these gases, enhancing the greenhouse effect, and starting to warm the Earth.The rate and extent of the warming depend, in part, on the global carbon cycle. If the rate at which the oceans remove CO2 from the atmosphere were faster, e.g., concentrations of CO2 would have increased less over the last century. If the processes removing carbon from the atmosphere and storing it on land were to diminish, concentrations of CO2 would increase more rapidly than projected on the basis of recent history. The processes responsible for adding carbon to, and withdrawing it from, the atmosphere are not well enough understood to predict future levels of CO2 with great accuracy. These processes are a part of the global carbon cycle.Some of the processes that add carbon to the atmosphere or remove it, such as the combustion of fossil fuels and the establishment of tree plantations, are under direct human control. Others, such as the accumulation of carbon in the oceans or on land as a result of changes in global climate (i.e., feedbacks between the global carbon cycle and climate), are not under direct human control except through controlling rates of greenhouse gas emissions and, hence, climatic change. Because CO2 has been more important than all of the other greenhouse gases under human control, combined, and is expected to continue so in the future, understanding the global carbon cycle is a vital part of managing global climate.This chapter addresses, first, the reservoirs and natural flows of carbon on the earth. It then addresses the sources of carbon to the atmosphere from human uses of land and energy and the sinks of carbon on land and in the oceans that have kept the atmospheric accumulation of CO2 lower than it would otherwise have been. The chapter describes changes in the distribution of carbon among the atmosphere, oceans, and terrestrial ecosystems over the past 150 years as a result of human-induced emissions of carbon. The processes responsible fo

Houghton, R. A.

2003-12-01

416

Compound cycle engine program  

NASA Technical Reports Server (NTRS)

The Compound Cycle Engine (CCE) is a highly turbocharged, power compounded power plant which combines the lightweight pressure rise capability of a gas turbine with the high efficiency of a diesel. When optimized for a rotorcraft, the CCE will reduce fuel burned for a typical 2 hr (plus 30 min reserve) mission by 30 to 40 percent when compared to a conventional advanced technology gas turbine. The CCE can provide a 50 percent increase in range-payload product on this mission. A program to establish the technology base for a Compound Cycle Engine is presented. The goal of this program is to research and develop those technologies which are barriers to demonstrating a multicylinder diesel core in the early 1990's. The major activity underway is a three-phased contract with the Garrett Turbine Engine Company to perform: (1) a light helicopter feasibility study, (2) component technology development, and (3) lubricant and material research and development. Other related activities are also presented.

Bobula, G. A.; Wintucky, W. T.; Castor, J. G.

1986-01-01

417

Are solar cycles predictable?  

NASA Astrophysics Data System (ADS)

Various methods (or recipes) have been proposed to predict future solar activity levels - with mixed success. Among these, some precursor methods based upon quantities determined around or a few years before solar minimum have provided rather high correlations with the strength of the following cycles. Recently, data assimilation with an advection-dominated (flux-transport) dynamo model has been proposed as a predictive tool, yielding remarkably high correlation coefficients. After discussing the potential implications of these results and the criticism that has been raised, we study the possible physical origin(s) of the predictive skill provided by precursor and other methods. It is found that the combination of the overlap of solar cycles and their amplitude-dependent rise time (Waldmeier's rule) introduces correlations in the sunspot number (or area) record, which account for the predictive skill of many precursor methods. This explanation requires no direct physical relation between the precursor quantity and the dynamo mechanism (in the sense of the Babcock-Leighton scheme or otherwise).

Schüssler, M.

2007-12-01

418

Rescue of corpus luteum function with peri-ovulatory HCG supplementation in IVF/ICSI GnRH antagonist cycles in which ovulation was triggered with a GnRH agonist: a pilot study.  

PubMed

Previous studies found a poor clinical outcome when a GnRH agonist (GnRHa) was used to trigger ovulation in GnRH antagonist IVF/ICSI cycles. This study aimed to determine the clinical and endocrine effects as well the optimal timing of HCG supplementation. Forty-five normogonadotrophic IVF/ICSI patients following a flexible antagonist protocol were prospectively randomized (sealed envelopes) to triggering of ovulation with a single bolus of either 10,000 IU of HCG (group 1, n = 15) or 0.5 mg buserelin s.c. In addition, the GnRHa triggered group was randomized into two groups: group 2 (n = 17) was supplemented with HCG 1500 IU, 12 h after ovulation induction and group 3 (n = 13) was supplemented with HCG 1500 IU 35 h after ovulation induction. Group 1 and group 3 had significantly higher luteal phase concentrations of progesterone (P < 0.001) as compared with group 2. Moreover, the clinical pregnancy rate of groups 1 and 3 was similar and significantly higher (P < 0.02) than that of group 2. A larger study, however, is required to substantiate these differences. No differences were seen regarding mid-luteal inhibin A concentrations between the three groups. Triggering of ovulation with GnRHa supplemented with 1500 IU HCG 35 h later (group 3) seems to secure a normal luteal phase and a normal clinical pregnancy outcome. PMID:16895629

Humaidan, P; Bungum, L; Bungum, M; Yding Andersen, C

2006-08-01

419

Assessment of the Potential Role of Tryptophan as the Precursor of Serotonin and Melatonin for the Aged Sleep-wake Cycle and Immune Function: Streptopelia Risoria as a Model  

PubMed Central

In the present review we summarize the relationship between the amino acid, tryptophan, the neurotransmitter, serotonin, and the indole, melatonin, with the rhythms of sleep/wake and the immune response along with the possible connections between the alterations in these rhythms due to aging and the so-called “serotonin and melatonin deficiency state.” The decrease associated with aging of the brain and circulating levels of serotonin and melatonin seemingly contributes to the alterations of both the sleep/wake cycle and the immune response that typically accompany old age. The supplemental administration of tryptophan, e.g. the inclusion of tryptophan-enriched food in the diet, might help to remediate these age-related alterations due to its capacity of raise the serotonin and melatonin levels in the brain and blood. Herein, we also summarize a set of studies related to the potential role that tryptophan, and its derived product melatonin, may play in the restoration of the aged circadian rhythms of sleep/wake and immune response, taking the ringdove (Streptopelia risoria) as a suitable model. PMID:22084580

Paredes, Sergio D.; Barriga, Carmen; Reiter, Russel J.; Rodríguez, Ana B.

2009-01-01

420

Rapid cycling medical synchrotron and beam delivery system  

DOEpatents

A medical synchrotron which cycles rapidly in order to accelerate particles for delivery in a beam therapy system. The synchrotron generally includes a radiofrequency (RF) cavity for accelerating the particles as a beam and a plurality of combined function magnets arranged in a ring. Each of the combined function magnets performs two functions. The first function of the combined function magnet is to bend the particle beam along an orbital path around the ring. The second function of the combined function magnet is to focus or defocus the particle beam as it travels around the path. The radiofrequency (RF) cavity is a ferrite loaded cavity adapted for high speed frequency swings for rapid cycling acceleration of the particles.

Peggs, Stephen G. (Port Jefferson, NY); Brennan, J. Michael (East Northport, NY); Tuozzolo, Joseph E. (Sayville, NY); Zaltsman, Alexander (Commack, NY)

2008-10-07

421

Oxidative photosynthetic carbon cycle or C2 cycle  

SciTech Connect

The oxidative photosynthetic carbon cycle (or C2 cycle) is the metabolic pathway responsible for photosynthetic oxygen uptake and the light-dependent production of carbon dioxide that is termed photorespiration. The C2 and reductive C3 cycles coexist, and combined, represent total photosynthetic carbon metabolism. A brief historical review is presented beginning with the early observations of the oxygen inhibition of photosynthesis up to the discovery of the oxygenase-activity associated with ribulose 1.5-bisphosphate carboxylase/oxygenase. The properties and the role of the compartmentalization of the enzymes involved with the pathway and the transport of C2, cycle intermediates are reviewed. The relationship of the C2 cycle to photorespiratory nitrogen metabolism and other associated metabolic pathways and the properties and regulation of the C2 cycle in diverse photosynthetic organisms are discussed. (Refs. 382).

Husic, D.W.; Husic, H.D.; Tolbert, N.E.

1987-01-01

422

What Makes Each Cycle Special? A Characterization of Hemispheric Cycles  

NASA Astrophysics Data System (ADS)

The solar cycle is the main instigator of changes in space weather and the environment in the heliosphere. For this reason it is important to have a detailed understanding of what elements make each cycle unique, and also of what characteristics tie all cycles together. Historically the sun has been always studied from a whole sun standpoint, but the northern and southern hemispheres present enough difference to warrant being studied individually. Here we characterize each hemispheric cycle separately, taking advantage of nearly two centuries of sunspot observations leading back to solar cycle 7. This sets the foundation for a more comprehensive understanding of the long-term evolution of the solar cycle and the solar magnetic field. This research was supported by the NSF grant for the Solar Physics REU Program at the Smithsonian Astrophysical Observatory (AGS-1263241) and the NASA Living With a Star Jack Eddy Postdoctoral Fellowship Program, administered by the UCAR Visiting Scientist Programs.

Senkpeil, R. R.; Munoz-Jaramillo, A.; DeLuca, E. E.