Photoperiodism and crassulacean acid metabolism : I. Immunological and kinetic evidences for different patterns of phosphoenolpyruvate carboxylase isoforms in photoperiodically inducible and non-inducible Crassulacean acid metabolism plants.

Science.gov (United States)

Brulfert, J; Müller, D; Kluge, M; Queiroz, O

1982-05-01

Plants of Kalanchoe blossfeldiana v. Poelln. Tom Thumb and Sedum morganianum E. Walth. were grown under controlled photoperiodic conditions under either short or long days. Gaz exchange measurements confirmed that in K. blossfeldiana Crassulacean acid metabolism (CAM) was photoperiodically inducible and that S. morganianum performed CAM independently of photoperiod. With K. blossfeldiana, a comparison of catalytic and regulatory properties of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) from short-day and long-day grown plants showed differences, but not with S. morganianum. Ouchterlony double diffusion tests and immunotitration experiments (using a S. morganianum PEPC antibody) established that CAM is induced in K. blossfeldiana-but not in S. morganianum-through the synthesis of a new PEPC isoform; this form shows an immunological behavior different from that prevailing under non-inductive conditions and can be considered as specific for CAM performance.

Recombinant thermoactive phosphoenolpyruvate carboxylase (PEPC) from Thermosynechococcus elongatus and its coupling with mesophilic/thermophilic bacterial carbonic anhydrases (CAs) for the conversion of CO2 to oxaloacetate.

Science.gov (United States)

Del Prete, Sonia; De Luca, Viviana; Capasso, Clemente; Supuran, Claudiu T; Carginale, Vincenzo

2016-01-15

With the continuous increase of atmospheric CO2 in the last decades, efficient methods for carbon capture, sequestration, and utilization are urgently required. The possibility of converting CO2 into useful chemicals could be a good strategy to both decreasing the CO2 concentration and for achieving an efficient exploitation of this cheap carbon source. Recently, several single- and multi-enzyme systems for the catalytic conversion of CO2 mainly to bicarbonate have been implemented. In order to design and construct a catalytic system for the conversion of CO2 to organic molecules, we implemented an in vitro multienzyme system using mesophilic and thermophilic enzymes. The system, in fact, was constituted by a recombinant phosphoenolpyruvate carboxylase (PEPC) from the thermophilic cyanobacterium Thermosynechococcus elongatus, in combination with mesophilic/thermophilic bacterial carbonic anhydrases (CAs), for converting CO2 into oxaloacetate, a compound of potential utility in industrial processes. The catalytic procedure is in two steps: the conversion of CO2 into bicarbonate by CA, followed by the carboxylation of phosphoenolpyruvate with bicarbonate, catalyzed by PEPC, with formation of oxaloacetate (OAA). All tested CAs, belonging to α-, β-, and γ-CA classes, were able to increase OAA production compared to procedures when only PEPC was used. Interestingly, the efficiency of the CAs tested in OAA production was in good agreement with the kinetic parameters for the CO2 hydration reaction of these enzymes. This PEPC also revealed to be thermoactive and thermostable, and when coupled with the extremely thermostable CA from Sulphurhydrogenibium azorense (SazCA) the production of OAA was achieved even if the two enzymes were exposed to temperatures up to 60 °C, suggesting a possible role of the two coupled enzymes in biotechnological processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Metabolic responses to pyruvate kinase deletion in lysine producing Corynebacterium glutamicum

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Wittmann Christoph

2008-03-01

Full Text Available Abstract Background Pyruvate kinase is an important element in flux control of the intermediate metabolism. It catalyzes the irreversible conversion of phosphoenolpyruvate into pyruvate and is under allosteric control. In Corynebacterium glutamicum, this enzyme was regarded as promising target for improved production of lysine, one of the major amino acids in animal nutrition. In pyruvate kinase deficient strains the required equimolar ratio of the two lysine precursors oxaloacetate and pyruvate can be achieved through concerted action of the phosphotransferase system (PTS and phosphoenolpyruvate carboxylase (PEPC, whereby a reduced amount of carbon may be lost as CO2 due to reduced flux into the tricarboxylic acid (TCA cycle. In previous studies, deletion of pyruvate kinase in lysine-producing C. glutamicum, however, did not yield a clear picture and the exact metabolic consequences are not fully understood. Results In this work, deletion of the pyk gene, encoding pyruvate kinase, was carried out in the lysine-producing strain C. glutamicum lysCfbr, expressing a feedback resistant aspartokinase, to investigate the cellular response to deletion of this central glycolytic enzyme. Pyk deletion was achieved by allelic replacement, verified by PCR analysis and the lack of in vitro enzyme activity. The deletion mutant showed an overall growth behavior (specific growth rate, glucose uptake rate, biomass yield which was very similar to that of the parent strain, but differed in slightly reduced lysine formation, increased formation of the overflow metabolites dihydroxyacetone and glycerol and in metabolic fluxes around the pyruvate node. The latter involved a flux shift from pyruvate carboxylase (PC to PEPC, by which the cell maintained anaplerotic supply of the TCA cycle. This created a metabolic by-pass from PEP to pyruvate via malic enzyme demonstrating its contribution to metabolic flexibility of C. glutamicum on glucose. Conclusion The metabolic

A simple enzymic method for the synthesis of [32P]phosphoenolpyruvate

International Nuclear Information System (INIS)

Parra, F.

1982-01-01

A rapid and simple enzymic method is described for the synthesis of [ 32 P]phosphoenolpyruvate from [ 32 P]Psub(i), with a reproducible yield of 74%. The final product was shown to be a good substrate for pyruvate kinase (EC 2.7.1.40). (author)

Decarboxylation of oxalacetate to pyruvate by purified avian liver phosphoenolpyruvate carboxykinase

Energy Technology Data Exchange (ETDEWEB)

Noce, P S; Utter, M F

1975-01-01

Phosphoenolpyruvate carboxykinase, which has been isolated from chicken liver mitochondria in essentially homogenous form, carries out the irreversible decarboxylation of oxalacetate to pyruvate in the presence of catalytic amounts of GDP or IDP, as well as the reversible decarboxylation of oxalacetate to phosphoenolpyruvate in the presence of substrate amounts of GTP or ITP. The pyruvate- and phosphoenolpyruvate-forming reactions are similar in their nucleoside specificity and appear to be carried out by the same protein. However, the two activities vary markedly in their response to added metal ions and sulfhydryl reagents. Phosphoenolpyruvate formation is completely dependent on the presence of a divalent metal ion, with Mn/sup 2 +/ the most effective species. This reaction is also stimulated by sulfhydryl reagents such as 2-mercaptoethanol. In contrast, the pyruvate-forming reaction is strongly inhibited by divalent metal ions, including Mn/sup 2 +/, and also by moderate concentrations of sulfhydryl reagents. These observations and the demonstration that pyruvate kinase-like activity is very low or absent make it unlikely that pyruvate formation proceeds via phosphoenolpyruvate as an intermediate. Although the pyruvate-forming reaction is inhibited by added metal ions, the reaction is also inhibited by metal-chelating agents such as 8-hydroxyquinoline and o-phenanthroline, suggesting that the reaction is dependent on the presence of a metal ion. It has not been possible, however, to demonstrate that the enzyme is a metalloprotein.

Regulatory Phosphorylation of Bacterial-Type PEP Carboxylase by the Ca2+-Dependent Protein Kinase RcCDPK1 in Developing Castor Oil Seeds.

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Ying, Sheng; Hill, Allyson T; Pyc, Michal; Anderson, Erin M; Snedden, Wayne A; Mullen, Robert T; She, Yi-Min; Plaxton, William C

2017-06-01

Phosphoenolpyruvate carboxylase (PEPC) is a tightly controlled cytosolic enzyme situated at a crucial branch point of central plant metabolism. In developing castor oil seeds ( Ricinus communis ) a novel, allosterically desensitized 910-kD Class-2 PEPC hetero-octameric complex, arises from a tight interaction between 107-kD plant-type PEPC and 118-kD bacterial-type (BTPC) subunits. The native Ca 2+ -dependent protein kinase (CDPK) responsible for in vivo inhibitory phosphorylation of Class-2 PEPC's BTPC subunit's at Ser-451 was highly purified from COS and identified as RcCDPK1 (XP_002526815) by mass spectrometry. Heterologously expressed RcCDPK1 catalyzed Ca 2+ -dependent, inhibitory phosphorylation of BTPC at Ser-451 while exhibiting: ( i ) a pair of Ca 2+ binding sites with identical dissociation constants of 5.03 μM, ( ii ) a Ca 2+ -dependent electrophoretic mobility shift, and ( iii ) a marked Ca 2+ -independent hydrophobicity. Pull-down experiments established the Ca 2+ -dependent interaction of N-terminal GST-tagged RcCDPK1 with BTPC. RcCDPK1-Cherry localized to the cytosol and nucleus of tobacco bright yellow-2 cells, but colocalized with mitochondrial-surface associated BTPC-enhanced yellow fluorescent protein when both fusion proteins were coexpressed. Deletion analyses demonstrated that although its N-terminal variable domain plays an essential role in optimizing Ca 2+ -dependent RcCDPK1 autophosphorylation and BTPC transphosphorylation activity, it is not critical for in vitro or in vivo target recognition. Arabidopsis ( Arabidopsis thaliana ) CPK4 and soybean ( Glycine max ) CDPKβ are RcCDPK1 orthologs that effectively phosphorylated castor BTPC at Ser-451. Overall, the results highlight a potential link between cytosolic Ca 2+ signaling and the posttranslational control of respiratory CO 2 refixation and anaplerotic photosynthate partitioning in support of storage oil and protein biosynthesis in developing COS. © 2017 American Society of Plant

Pyramiding expression of maize genes encoding phosphoenolpyruvate carboxylase (PEPC) and pyruvate orthophosphate dikinase (PPDK) synergistically improve the photosynthetic characteristics of transgenic wheat.

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Zhang, HuiFang; Xu, WeiGang; Wang, HuiWei; Hu, Lin; Li, Yan; Qi, XueLi; Zhang, Lei; Li, ChunXin; Hua, Xia

2014-09-01

Using particle bombardment transformation, we introduced maize pepc cDNA encoding phosphoenolpyruvate carboxylase (PEPC) and ppdk cDNA encoding pyruvate orthophosphate dikinase (PPDK) into the C3 crop wheat to generate transgenic wheat lines carrying cDNA of pepc (PC lines), ppdk (PK lines) or both (PKC lines). The integration, transcription, and expression of the foreign genes were confirmed by Southern blot, Real-time quantitative reverse transcription PCR (Q-RT-PCR), and Western blot analysis. Q-RT-PCR results indicated that the average relative expression levels of pepc and ppdk in the PKC lines reached 10 and 4.6, respectively, compared to their expressions in untransformed plants (set to 1). The enzyme activities of PEPC and PPDK in the PKC lines were 4.3- and 2.1-fold higher, respectively, than in the untransformed control. The maximum daily net photosynthetic rates of the PKC, PC, and PK lines were enhanced by 26.4, 13.3, and 4.5%, respectively, whereas the diurnal accumulations of photosynthesis were 21.3, 13.9, and 6.9%, respectively, higher than in the control. The Fv/Fm of the transgenic plants decreased less than in the control under high temperature and high light conditions (2 weeks after anthesis), suggesting that the transgenic wheat transports more absorbed light energy into a photochemical reaction. The exogenous maize C4-specific pepc gene was more effective than ppdk at improving the photosynthetic performance and yield characteristics of transgenic wheat, while the two genes showed a synergistic effect when they were transformed into the same genetic background, because the PKC lines exhibited improved photosynthetic and physiological traits.

Physiological investigation of C4-phosphoenolpyruvate-carboxylase-introduced rice line shows that sucrose metabolism is involved in the improved drought tolerance.

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Zhang, Chen; Li, Xia; He, Yafei; Zhang, Jinfei; Yan, Ting; Liu, Xiaolong

2017-06-01

We compared the drought tolerance of wild-type (WT) and transgenic rice plants (PC) over-expressing the maize C 4 PEPC gene, which encodes phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) gene, and evaluated the roles of saccharide and sugar-related enzymes in the drought response. Pot-grown seedlings were subjected to real drought conditions outdoors, and the yield components were compared between PC and untransformed wild-type (WT) plants. The stable yield from PC plants was associated with higher net photosynthetic rate under the real drought treatment. The physiological characters of WT and PC seedlings under a simulated drought treatment (25% (w/v) polyethylene glycol-6000 for 3 h; PEG 6000 treatment) were analyzed in detail for the early response of drought. The relative water content was higher in PC than in WT, and PEPC activity and the C 4 -PEPC transcript level in PC were elevated under the simulated drought conditions. The endogenous saccharide responses also differed between PC and WT under simulated drought stress. The higher sugar decomposition rate in PC than in WT under drought analog stress was related to the increased activities of sucrose phosphate synthase, sucrose synthase, acid invertase, and neutral invertase, increased transcript levels of VIN1, CIN1, NIN1, SUT2, SUT4, and SUT5, and increased activities of superoxide dismutase and peroxidase in the leaves. The greater antioxidant defense capacity of PC and its relationship with saccharide metabolism was one of the reasons for the improved drought tolerance. In conclusion, PEPC effectively alleviated oxidative damage and enhanced the drought tolerance in rice plants, which were more related to the increase of the endogenous saccharide decomposition. These findings show that components of C 4 photosynthesis can be used to increase the yield of rice under drought conditions. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Changes in the isozymic pattern of phosphoenolpyruvate : An early step in photoperiodic control of crassulacean acid metabolism level.

Science.gov (United States)

Brulfert, J; Arrabaça, M C; Guerrier, D; Queiroz, O

1979-01-01

Two major isofunctional forms of phosphoenolpyruvate carboxylase (EC 4.1.1.31) have been separated from the leaves of Kalanchoe blossfeldiana Poelln. Tom Thumb by acrylamide gel electrophoresis and diethylaminoethyl cellulose techniques: one of the forms prevails under long-day treatment (low crassulacean acid metabolism level), the other develops under short-day treatment (high Crassulacean acid metabolism level). Molecular weights are significantly different: 175·10(3) and 186·10(3), respectively. These results indicate that two populations of phosphoenolyruvate carboxylase are present in the plant, one of which is responsible for Crassulacean acid metabolism activity under the control of photoperiod.The Crassulacean acid metabolism appears to depend on the same endogenous clock that governs other photoperiodically controlled events (e.g. flowering). The metabolic and energetic significance of this feature is discussed. It is suggested that modification in isozymic composition could be an early step in the response to photoperiodism at the metabolic level.

Regulatory Phosphorylation of Bacterial-Type PEP Carboxylase by the Ca2+-Dependent Protein Kinase RcCDPK1 in Developing Castor Oil Seeds1[OPEN

Science.gov (United States)

Hill, Allyson T.; Anderson, Erin M.; She, Yi-Min

2017-01-01

Phosphoenolpyruvate carboxylase (PEPC) is a tightly controlled cytosolic enzyme situated at a crucial branch point of central plant metabolism. In developing castor oil seeds (Ricinus communis) a novel, allosterically desensitized 910-kD Class-2 PEPC hetero-octameric complex, arises from a tight interaction between 107-kD plant-type PEPC and 118-kD bacterial-type (BTPC) subunits. The native Ca2+-dependent protein kinase (CDPK) responsible for in vivo inhibitory phosphorylation of Class-2 PEPC’s BTPC subunit’s at Ser-451 was highly purified from COS and identified as RcCDPK1 (XP_002526815) by mass spectrometry. Heterologously expressed RcCDPK1 catalyzed Ca2+-dependent, inhibitory phosphorylation of BTPC at Ser-451 while exhibiting: (i) a pair of Ca2+ binding sites with identical dissociation constants of 5.03 μM, (ii) a Ca2+-dependent electrophoretic mobility shift, and (iii) a marked Ca2+-independent hydrophobicity. Pull-down experiments established the Ca2+-dependent interaction of N-terminal GST-tagged RcCDPK1 with BTPC. RcCDPK1-Cherry localized to the cytosol and nucleus of tobacco bright yellow-2 cells, but colocalized with mitochondrial-surface associated BTPC-enhanced yellow fluorescent protein when both fusion proteins were coexpressed. Deletion analyses demonstrated that although its N-terminal variable domain plays an essential role in optimizing Ca2+-dependent RcCDPK1 autophosphorylation and BTPC transphosphorylation activity, it is not critical for in vitro or in vivo target recognition. Arabidopsis (Arabidopsis thaliana) CPK4 and soybean (Glycine max) CDPKβ are RcCDPK1 orthologs that effectively phosphorylated castor BTPC at Ser-451. Overall, the results highlight a potential link between cytosolic Ca2+ signaling and the posttranslational control of respiratory CO2 refixation and anaplerotic photosynthate partitioning in support of storage oil and protein biosynthesis in developing COS. PMID:28363991

Comparative toxicity of four chlorinated dibenzo-p-dioxins (CDDs) and their mixture. Pt. 2. Structure-activity relationships with inhibition of hepatic phosphoenolpyruvate carboxykinase, pyruvate carboxylase, and [gamma]-glutamyl transpeptidase activities

Energy Technology Data Exchange (ETDEWEB)

Weber, L.W.D.; Stahl, B.U.; Rozman, K. (Kansas Univ. Medical Center, Dept. of Pharmacology, Toxicology and Therapeutics, Kansas City, KS (United States) GSF, Inst. fuer Toxikologie, Neuherberg (Germany)); Lebofsky, M. (Kansas Univ. Medical Center, Dept. of Pharmacology, Toxicology and Therapeutics, Kansas City, KS (United States)); Kettrup, A. (GSF, Inst. fuer Oekologische Chemie, Neuherberg (Germany))

1992-08-01

Male Sprague-Dawley rats were treated with an LD[sub 20], LD[sub 50] and LD[sub 80] respectively, of tetra-, penta-, hexa-, hepta-CDD and a mixture of the four CDDs, all carrying chlorine substituents in the biologically crucial 2,3,7, and 8 positions. Specific activities of two key enzymes of gluconeogenesis, viz, phosphoenolpyruvate carboxylkinase (PEPCK) and pyruvate carboxylase (PC), as well as the activity of the preneoplastic marker enzyme [gamma]-glutamyl transpeptidase ([gamma]-GT), were determined in livers of CDD-treated and ad libitum-fed control animals. PEPCK activity showed evidence for dose-related inhibition on the second day after dosing; PC activity was slightly reduced, whereas [gamma]-GT activity was dose-dependently inhibited. By 8 days after dosing PEPCK activities were dose-dependently decreased after administration of all four CDDs and their mixture. PC activities were significantly reduced, but no dose-response was evident. The activity of [gamma]-GT was dose-dependently inhibited, but only to a value of 25% below control activities. It is concluded that CDDs share a common mechanism of acute toxicity, viz, inhibition of glucocorticoid-dependent enzymes which results in a derailment of intermediary metabolism not compatible with survival of the animals. (orig.).

Gluconeogenesis in Leishmania mexicana: contribution of glycerol kinase, phosphoenolpyruvate carboxykinase, and pyruvate phosphate dikinase.

Science.gov (United States)

Rodriguez-Contreras, Dayana; Hamilton, Nicklas

2014-11-21

Gluconeogenesis is an active pathway in Leishmania amastigotes and is essential for their survival within the mammalian cells. However, our knowledge about this pathway in trypanosomatids is very limited. We investigated the role of glycerol kinase (GK), phosphoenolpyruvate carboxykinase (PEPCK), and pyruvate phosphate dikinase (PPDK) in gluconeogenesis by generating the respective Leishmania mexicana Δgk, Δpepck, and Δppdk null mutants. Our results demonstrated that indeed GK, PEPCK, and PPDK are key players in the gluconeogenesis pathway in Leishmania, although stage-specific differences in their contribution to this pathway were found. GK participates in the entry of glycerol in promastigotes and amastigotes; PEPCK participates in the entry of aspartate in promastigotes, and PPDK is involved in the entry of alanine in amastigotes. Furthermore, the majority of alanine enters into the pathway via decarboxylation of pyruvate in promastigotes, whereas pathway redundancy is suggested for the entry of aspartate in amastigotes. Interestingly, we also found that l-lactate, an abundant glucogenic precursor in mammals, was used by Leishmania amastigotes to synthesize mannogen, entering the pathway through PPDK. On the basis of these new results, we propose a revision in the current model of gluconeogenesis in Leishmania, emphasizing the differences between amastigotes and promastigotes. This work underlines the importance of studying the trypanosomatid intracellular life cycle stages to gain a better understanding of the pathologies caused in humans. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Improved analysis of C4 and C3 photosynthesis via refined in vitro assays of their carbon fixation biochemistry

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Sharwood, Robert E.; Sonawane, Balasaheb V.; Ghannoum, Oula; Whitney, Spencer M.

2016-01-01

Plants operating C3 and C4 photosynthetic pathways exhibit differences in leaf anatomy and photosynthetic carbon fixation biochemistry. Fully understanding this underpinning biochemical variation is requisite to identifying solutions for improving photosynthetic efficiency and growth. Here we refine assay methods for accurately measuring the carboxylase and decarboxylase activities in C3 and C4 plant soluble protein. We show that differences in plant extract preparation and assay conditions are required to measure NADP-malic enzyme and phosphoenolpyruvate carboxylase (pH 8, Mg2+, 22 °C) and phosphoenolpyruvate carboxykinase (pH 7, >2mM Mn2+, no Mg2+) maximal activities accurately. We validate how the omission of MgCl2 during leaf protein extraction, lengthy (>1min) centrifugation times, and the use of non-pure ribulose-1,5-bisphosphate (RuBP) significantly underestimate Rubisco activation status. We show how Rubisco activation status varies with leaf ontogeny and is generally lower in mature C4 monocot leaves (45–60% activation) relative to C3 monocots (55–90% activation). Consistent with their >3-fold lower Rubisco contents, full Rubisco activation in soluble protein from C4 leaves (<5min) was faster than in C3 plant samples (<10min), with addition of Rubisco activase not required for full activation. We conclude that Rubisco inactivation in illuminated leaves primarily stems from RuBP binding to non-carbamylated enzyme, a state readily reversible by dilution during cellular protein extraction. PMID:27122573

Photoperiodism and Crassulacean acid metabolism : II. Relations between leaf aging and photoperiod in Crassulacean acid metabolism induction.

Science.gov (United States)

Brulfert, J; Guerrier, D; Queiroz, O

1982-05-01

Measurements of net CO2 exchange, malate accumulation, properties and capacity of phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) in leaves of different ages of two short-day dependent Crassulacean acid metabolism (CAM) plants (Kalanchoe blossfeldiana v. Poelln. Tom thumb and K. velutina Welw.) show that, in both species: a) young leaves from plants grown under long days display a CO2 exchange pattern typical of C3 plants; b) leaf aging promotes CAM under long-day conditions; c) short-day treatment induces CAM in young leaves to a higher degree than aging under long days; d) at least in K. blossfeldiana, the PEPC form developed with leaf aging under long days and the enzyme form synthetized de novo in young leaves grown under short days were shown to have similar properties. Short days also promote CAM in older leaves though at a lesser extent than in young leaves: The result is that this photoperiodic treatment increases the general level of CAM performance by the whole plant. The physiological meaning of the control of PEPC capacity by photoperiodism could be to afford a precisely timed seasonal increase in CAM potentiality, enabling the plant to immediately optimize its response to the onset of drought periods.

Photosynthetic carbon assimilation in the coccolithophorid Emiliania huxleyi (Haptophyta): Evidence for the predominant operation of the c3 cycle and the contribution of {beta}-carboxylases to the active anaplerotic reaction.

Science.gov (United States)

Tsuji, Yoshinori; Suzuki, Iwane; Shiraiwa, Yoshihiro

2009-02-01

The coccolithophorid Emiliania huxleyi (Haptophyta) is a representative and unique marine phytoplankton species that fixes inorganic carbon by photosynthesis and calci-fication. We examined the initial process of photosynthetic carbon assimilation by analyses of metabolites, enzymes and genes. When the cells were incubated with a radioactive substrate (2.3 mM NaH(14)CO(3)) for 10 s under illumination, 70% of the (14)C was incorporated into the 80% methanol-soluble fraction. Eighty-five and 15% of (14)C in the soluble fraction was incorporated into phosphate esters (P-esters), including the C(3) cycle intermediates and a C(4) compound, aspartate, respectively. A pulse-chase experiment showed that (14)C in P-esters was mainly transferred into lipids, while [(14)C]aspartate, [(14)C]alanine and [(14)C]glutamate levels remained almost constant. These results indicate that the C(3) cycle functions as the initial pathway of carbon assimilation and that beta-carboxylation contributes to the production of amino acids in subsequent metabolism. Transcriptional analysis of beta-carboxylases such as pyruvate carboxylase (PYC), phosphoenolpyruvate carboxylase (PEPC) and phosphoenolpyruvate carboxykinase (PEPCK) revealed that PYC and PEPC transcripts were greatly increased under illumination, whereas the PEPCK transcript decreased remarkably. PEPC activity was higher in light-grown cells than in dark-adapted cells. PYC activity was detected in isolated chloroplasts of light-grown cells. According to analysis of their deduced N-terminal sequence, PYC and PEPC are predicted to be located in the chloroplasts and mitochondria, respectively. These results suggest that E. huxleyi possesses unique carbon assimila-tion mechanisms in which beta-carboxylation by both PYC and PEPC plays important roles in different organelles.

LCE: leaf carbon exchange data set for tropical, temperate, and boreal species of North and Central America.

Science.gov (United States)

Smith, Nicholas G; Dukes, Jeffrey S

2017-11-01

Leaf canopy carbon exchange processes, such as photosynthesis and respiration, are substantial components of the global carbon cycle. Climate models base their simulations of photosynthesis and respiration on an empirical understanding of the underlying biochemical processes, and the responses of those processes to environmental drivers. As such, data spanning large spatial scales are needed to evaluate and parameterize these models. Here, we present data on four important biochemical parameters defining leaf carbon exchange processes from 626 individuals of 98 species at 12 North and Central American sites spanning ~53° of latitude. The four parameters are the maximum rate of Rubisco carboxylation (V cmax ), the maximum rate of electron transport for the regeneration of Ribulose-1,5,-bisphosphate (J max ), the maximum rate of phosphoenolpyruvate carboxylase carboxylation (V pmax ), and leaf dark respiration (R d ). The raw net photosynthesis by intercellular CO 2 (A/C i ) data used to calculate V cmax , J max , and V pmax rates are also presented. Data were gathered on the same leaf of each individual (one leaf per individual), allowing for the examination of each parameter relative to others. Additionally, the data set contains a number of covariates for the plants measured. Covariate data include (1) leaf-level traits (leaf mass, leaf area, leaf nitrogen and carbon content, predawn leaf water potential), (2) plant-level traits (plant height for herbaceous individuals and diameter at breast height for trees), (3) soil moisture at the time of measurement, (4) air temperature from nearby weather stations for the day of measurement and each of the 90 d prior to measurement, and (5) climate data (growing season mean temperature, precipitation, photosynthetically active radiation, vapor pressure deficit, and aridity index). We hope that the data will be useful for obtaining greater understanding of the abiotic and biotic determinants of these important biochemical

Effect of glycolate on the activity of ribulosediphosphate and phosphoenolpyruvate carboxylases in C/sub 3/ and C/sub 4/ plants at different O/sub 2/ concentrations

Energy Technology Data Exchange (ETDEWEB)

Popova, L; Dimitrova, O [Bylgarska Akademiya na Naukite, Sofia. Inst. po Fiziologiya na Rasteniyata

1981-01-01

The experiments are carried out with pisum and maize plants grown in a chamber under controlled conditions. The activity of the two enzymes is recorded by the amount of fixed H/sup 14/CO/sub 3/ in acid-stable products of the reactions. The effect of glycolate on the activity of the carboxylating enzymes is largely related to the effect of O/sub 2/ on the activity of the RuDP and PEP carboxylases. The stimulating effect of glucolate on the activity of the carboxylating enzymes is probably of a regulatory significance. An essential conclusion is that O/sub 2/ attacks C/sub 4/ photosynthesis not only on inhibiting the RuDP carboxylase in bundle sheath cells, but it also inhibits the activity of the main carboxylating enzyme in C/sub 4/ plants-the PEP carboxylase.

Adaxial/abaxial specification in the regulation of photosynthesis and stomatal opening with respect to light orientation and growth with CO2 enrichment in the C4 species Paspalum dilatatum.

Science.gov (United States)

Soares, Ana Sofia; Driscoll, Simon P; Olmos, Enrique; Harbinson, Jeremy; Arrabaça, Maria Celeste; Foyer, Christine H

2008-01-01

Whole-plant morphology, leaf structure and composition were studied together with the effects of light orientation on the dorso-ventral regulation of photosynthesis and stomatal conductance in Paspalum dilatatum cv. Raki plants grown for 6 wk at either 350 or 700 microl l(-1) CO(2). Plant biomass was doubled as a result of growth at high CO(2) and the shoot:root ratio was decreased. Stomatal density was increased in the leaves of the high CO(2)-grown plants, which had greater numbers of smaller stomata and more epidermal cells on the abaxial surface. An asymmetric surface-specific regulation of photosynthesis and stomatal conductance was observed with respect to light orientation. This was not caused by dorso-ventral variations in leaf structure, the distribution of phosphoenolpyruvate carboxylase (PEPC) and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) proteins or light absorptance, transmittance or reflectance. Adaxial/abaxial specification in the regulation of photosynthesis results from differential sensitivity of stomatal opening to light orientation and fixed gradients of enzyme activation across the leaf.

Growth of the C4 dicot Flaveria bidentis: photosynthetic acclimation to low light through shifts in leaf anatomy and biochemistry.

Science.gov (United States)

Pengelly, Jasper J L; Sirault, Xavier R R; Tazoe, Youshi; Evans, John R; Furbank, Robert T; von Caemmerer, Susanne

2010-09-01

In C(4) plants, acclimation to growth at low irradiance by means of anatomical and biochemical changes to leaf tissue is considered to be limited by the need for a close interaction and coordination between bundle sheath and mesophyll cells. Here differences in relative growth rate (RGR), gas exchange, carbon isotope discrimination, photosynthetic enzyme activity, and leaf anatomy in the C(4) dicot Flaveria bidentis grown at a low (LI; 150 micromol quanta m(2) s(-1)) and medium (MI; 500 micromol quanta m(2) s(-1)) irradiance and with a 12 h photoperiod over 36 d were examined. RGRs measured using a 3D non-destructive imaging technique were consistently higher in MI plants. Rates of CO(2) assimilation per leaf area measured at 1500 micromol quanta m(2) s(-1) were higher for MI than LI plants but did not differ on a mass basis. LI plants had lower Rubisco and phosphoenolpyruvate carboxylase activities and chlorophyll content on a leaf area basis. Bundle sheath leakiness of CO(2) (phi) calculated from real-time carbon isotope discrimination was similar for MI and LI plants at high irradiance. phi increased at lower irradiances, but more so in MI plants, reflecting acclimation to low growth irradiance. Leaf thickness and vein density were greater in MI plants, and mesophyll surface area exposed to intercellular airspace (S(m)) and bundle sheath surface area per unit leaf area (S(b)) measured from leaf cross-sections were also both significantly greater in MI compared with LI leaves. Both mesophyll and bundle sheath conductance to CO(2) diffusion were greater in MI compared with LI plants. Despite being a C(4) species, F. bidentis is very plastic with respect to growth irradiance.

A unified molecular mechanism for the regulation of acetyl-CoA carboxylase by phosphorylation.

Science.gov (United States)

Wei, Jia; Zhang, Yixiao; Yu, Tai-Yuan; Sadre-Bazzaz, Kianoush; Rudolph, Michael J; Amodeo, Gabriele A; Symington, Lorraine S; Walz, Thomas; Tong, Liang

2016-01-01

Acetyl-CoA carboxylases (ACCs) are crucial metabolic enzymes and attractive targets for drug discovery. Eukaryotic acetyl-CoA carboxylases are 250 kDa single-chain, multi-domain enzymes and function as dimers and higher oligomers. Their catalytic activity is tightly regulated by phosphorylation and other means. Here we show that yeast ACC is directly phosphorylated by the protein kinase SNF1 at residue Ser1157, which potently inhibits the enzyme. Crystal structure of three ACC central domains (AC3-AC5) shows that the phosphorylated Ser1157 is recognized by Arg1173, Arg1260, Tyr1113 and Ser1159. The R1173A/R1260A double mutant is insensitive to SNF1, confirming that this binding site is crucial for regulation. Electron microscopic studies reveal dramatic conformational changes in the holoenzyme upon phosphorylation, likely owing to the dissociation of the biotin carboxylase domain dimer. The observations support a unified molecular mechanism for the regulation of ACC by phosphorylation as well as by the natural product soraphen A, a potent inhibitor of eukaryotic ACC. These molecular insights enhance our understanding of acetyl-CoA carboxylase regulation and provide a basis for drug discovery.

Light-stimulated accumulation of transcripts of nuclear and chloroplast genes for ribulosebisphosphate carboxylase

Energy Technology Data Exchange (ETDEWEB)

Smith, S M; Ellis, R J

1981-01-01

The chloroplast enzyme, ribulosebisphosphate carboxylase, consists of large subunit polypeptides encoded in the chloroplast genome and small subunit polypeptides encoded in the nuclear genome. Cloned DNA complementary to the small subunit mRNA hybridizes to a single RNA species of 900-1000 nucleotides in both total and poly(A)-containing RNA from leaves of Pisum sativum, but does not hybridize to chloroplast RNA. Small subunit cDNA hybridizes to at least three RNA species from nuclei, two of which are of higher molecular weight than the mature mRNA. A cloned large subunit DNA sequence hybridizes to a single species of Pisum chloroplast RNA containing approximately 1700 nucleotides, but does not hybridize to nuclear RNA. The light-stimulation of carboxylase accumulation reflects increases in the amounts of transcripts for both subunits in total leaf RNA. Transcripts of the small subunit gene are more abundant in nuclear RNA from light-grown leaves than in that from dark-grown leaves. These results suggest that the stimulation of carboxylase accumulation by light is mediated at the level of either transcription or RNA turnover in both nucleus and chloroplast.

Electron microscopy of the complexes of ribulose-1,5-bisphosphate carboxylase (Rubisco) and Rubisco subunit-binding protein from pea leaves

NARCIS (Netherlands)

Tsuprun, V.L.; Boekema, E.J.; Samsonidze, T.G.; Pushkin, A.V.

1991-01-01

The structure of ribulose-1,5-bisphosphate carboxylase (Rubisco) subunit-binding protein and its interaction with pea leaf chloroplast Rubisco were studied by electron microscopy and image analysis. Electron-microscopic evidence for the association of Rubisco subunit-binding protein, consisting of

Biochemical studies on the effect of fluoride on higher plants. 3. The effect of fluoride on dark carbon dioxide fixation

Energy Technology Data Exchange (ETDEWEB)

Yang, S F; Miller, G W

1963-01-01

Dark CO/sub 2/ fixation and phosphoenolpyruvate-carboxylase activity were studied in fluoride-necrotic and control soya-bean leaves. Necrotic leaves had a higher rate of dark CO/sub 2/ fixation than control leaves both in vivo and in vitro (phosphoenolpyruvate carboxylase). Results suggested that the accumulation of organic acids and amino acids in necrotic leaves resulted from an increased rate of dark CO/sub 2/ fixation. The possible role of fluoride in stimulating the carboxylation and its implication to necrosis are discussed.

Drought-Induced Effects on Nitrate Reductase Activity and mRNA and on the Coordination of Nitrogen and Carbon Metabolism in Maize Leaves1

Science.gov (United States)

Foyer, Christine H.; Valadier, Marie-Hélène; Migge, Andrea; Becker, Thomas W.

1998-01-01

Maize (Zea mays L.) plants were grown to the nine-leaf stage. Despite a saturating N supply, the youngest mature leaves (seventh position on the stem) contained little NO3− reserve. Droughted plants (deprived of nutrient solution) showed changes in foliar enzyme activities, mRNA accumulation, photosynthesis, and carbohydrate and amino acid contents. Total leaf water potential and CO2 assimilation rates, measured 3 h into the photoperiod, decreased 3 d after the onset of drought. Starch, glucose, fructose, and amino acids, but not sucrose (Suc), accumulated in the leaves of droughted plants. Maximal extractable phosphoenolpyruvate carboxylase activities increased slightly during water deficit, whereas the sensitivity of this enzyme to the inhibitor malate decreased. Maximal extractable Suc phosphate synthase activities decreased as a result of water stress, and there was an increase in the sensitivity to the inhibitor orthophosphate. A correlation between maximal extractable foliar nitrate reductase (NR) activity and the rate of CO2 assimilation was observed. The NR activation state and maximal extractable NR activity declined rapidly in response to drought. Photosynthesis and NR activity recovered rapidly when nutrient solution was restored at this point. The decrease in maximal extractable NR activity was accompanied by a decrease in NR transcripts, whereas Suc phosphate synthase and phosphoenolpyruvate carboxylase mRNAs were much less affected. The coordination of N and C metabolism is retained during drought conditions via modulation of the activities of Suc phosphate synthase and NR commensurate with the prevailing rate of photosynthesis. PMID:9576798

Interaction Between the Biotin Carboxyl Carrier Domain and the Biotin Carboxylase Domain in Pyruvate Carboxylase from Rhizobium etli†

Science.gov (United States)

Lietzan, Adam D.; Menefee, Ann L.; Zeczycki, Tonya N.; Kumar, Sudhanshu; Attwood, Paul V.; Wallace, John C.; Cleland, W. Wallace; Maurice, Martin St.

2011-01-01

Pyruvate carboxylase (PC) catalyzes the ATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in mammalian tissues. To effect catalysis, the tethered biotin of PC must gain access to active sites in both the biotin carboxylase domain and the carboxyl transferase domain. Previous studies have demonstrated that a mutation of threonine 882 to alanine in PC from Rhizobium etli renders the carboxyl transferase domain inactive and favors the positioning of biotin in the biotin carboxylase domain. We report the 2.4 Å resolution X-ray crystal structure of the Rhizobium etli PC T882A mutant which reveals the first high-resolution description of the domain interaction between the biotin carboxyl carrier protein domain and the biotin carboxylase domain. The overall quaternary arrangement of Rhizobium etli PC remains highly asymmetrical and is independent of the presence of allosteric activator. While biotin is observed in the biotin carboxylase domain, its access to the active site is precluded by the interaction between Arg353 and Glu248, revealing a mechanism for regulating carboxybiotin access to the BC domain active site. The binding location for the biotin carboxyl carrier protein domain demonstrates that tethered biotin cannot bind in the biotin carboxylase domain active site in the same orientation as free biotin, helping to explain the difference in catalysis observed between tethered biotin and free biotin substrates in biotin carboxylase enzymes. Electron density located in the biotin carboxylase domain active site is assigned to phosphonoacetate, offering a probable location for the putative carboxyphosphate intermediate formed during biotin carboxylation. The insights gained from the T882A Rhizobium etli PC crystal structure provide a new series of catalytic snapshots in PC and offer a revised perspective on catalysis in the biotin-dependent enzyme family. PMID:21958016

Application of a Novel and Automated Branched DNA in Situ Hybridization Method for the Rapid and Sensitive Localization of mRNA Molecules in Plant Tissues

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Andrew J. Bowling

2014-04-01

Full Text Available Premise of the study: A novel branched DNA detection technology, RNAscope in situ hybridization (ISH, originally developed for use on human clinical and animal tissues, was adapted for use in plant tissue in an attempt to overcome some of the limitations associated with traditional ISH assays. Methods and Results: Zea mays leaf tissue was formaldehyde fixed and paraffin embedded (FFPE and then probed with the RNAscope ISH assay for two endogenous genes, phosphoenolpyruvate carboxylase (PEPC and phosphoenolpyruvate carboxykinase (PEPCK. Results from both manual and automated methods showed tissue- and cell-specific mRNA localization patterns expected from these well-studied genes. Conclusions: RNAscope ISH is a sensitive method that generates high-quality, easily interpretable results from FFPE plant tissues. Automation of the RNAscope method on the Ventana Discovery Ultra platform allows significant advantages for repeatability, reduction in variability, and flexibility of workflow processes.

Escherichia coli Phosphoenolpyruvate-Dependent Phosphotransferase System : Mechanism of Phosphoryl-Group Transfer from Phosphoenolpyruvate to HPr

NARCIS (Netherlands)

Misset, Onno; Robillard, George T.

1982-01-01

The mechanism of phosphoryl-group transfer from phosphoenolpyruvate (PEP) to HPr, catalyzed by enzyme I of the Escherichia coli PEP-dependent phosphotransferase system, has been studied in vitro. Steady-state kinetics and isotope exchange measurements revealed that this reaction cannot be described

Identification of genes induced by salt stress from Medicago ...

African Journals Online (AJOL)

Among these protein, citrate synthase, ribulose- 1,5-bisphosphate carboxylase, chloroplast protein, phosphoenolpyruvate carboxylase and chloroplast outer envelope protein are related to photosynthesis; DNA binding/transcription factor, putative AP2/EREBP transcription factor, Cab9 gene, photosystem II polypeptide and ...

Assay of ribulose bisphosphate carboxylase

International Nuclear Information System (INIS)

Pike, C.; Berry, J.

1987-01-01

Assays of ribulose bisphosphate carboxylase (rubisco) can be used to illustrate many properties of photosynthetic systems. Many different leaves have been assayed with this standard procedure. The tissue is ground with a mortar and pestle in extraction buffer. The supernatant after centrifugation is used as the source of enzyme. Buffer, RuBP, [ 14 C]-NaHCO 3 , and enzyme are combined in a scintillation vial; the reaction is run for 1 min at 30 0 . The acid-stable products are counted. Reproducibility in student experiments has been excellent. The assay data can be combined with analyses of leaf properties such as fresh and dry weight, chlorophyll and protein content, etc. Students have done projects such as the response of enzyme to temperature and to various inhibitors. They also report on the use of a transition state analog, carboxyarabinitol bisphosphate, to titrate the molar concentration of rubisco molecules (active sites) in an enzyme sample. Thus, using crude extracts the catalytic activity of a sample can be compared to the absolute quantity of enzyme or to the turnover number

Strategies to lower greenhouse gas level by rice agriculture | Hsu ...

African Journals Online (AJOL)

The transgenic rice (basically a C3 plant) harboring C4 photosynthetic genes phosphoenolpyruvate carboxylase (PEP) carboxylase (PEPC) and pyruvate orthophosphate dikinase (PPDK) has been showed to increased photosynthetic capacity and efficiency of carbon dioxide assimilation. However, many drawbacks that is, ...

Effect of biotin on activity and gene expression of biotin-dependent carboxylases in the liver of dairy cows.

Science.gov (United States)

Ferreira, G; Weiss, W P

2007-03-01

Biotin is a cofactor of the gluconeogenic enzymes pyruvate carboxylase (PC) and propionyl-coenzyme A carboxylase (PCC). We hypothesized that biotin supplementation increases the activity and gene expression of PC and PCC and the gene expression of phosphoenol-pyruvate carboxykinase (PEPCK) in the liver of lactating dairy cows. Eight multiparous Holstein cows (40 +/- 2 kg/d of milk yield and 162 +/- 35 d in milk) were randomly assigned to 1 of 2 diet sequences in a crossover design with two 22-d periods. Treatments consisted of a basal diet (60% concentrate) containing 0 or 0.96 mg/kg of supplemental biotin. On d 21 of each period, liver tissue was collected by percutaneous liver biopsy. Activities of PC and PCC were determined by measuring the fixation of [14C]O2 in liver homogenates. Abundance of mRNA for PCC, PC, and PEPCK was determined by quantitative reverse-transcription PCR. Biotin supplementation did not affect milk production or composition. Biotin supplementation increased the activity of PC but had no effect on PCC activity. Biotin supplementation did not affect the gene expression of PC, PCC, and PEPCK. The increased activity of PC without changes in mRNA abundance may have been caused by increased activation of the apoenzymes by holocarboxylase synthetase. In conclusion, biotin supplementation affected the activity of PC in the liver of lactating dairy cows, but whether biotin supplementation increases glucose production in the liver remains to be determined.

Photosynthesis in Flaveria brownii, a C(4)-Like Species: Leaf Anatomy, Characteristics of CO(2) Exchange, Compartmentation of Photosynthetic Enzymes, and Metabolism of CO(2).

Science.gov (United States)

Cheng, S H; Moore, B D; Edwards, G E; Ku, M S

1988-08-01

Light microscopic examination of leaf cross-sections showed that Flaveria brownii A. M. Powell exhibits Kranz anatomy, in which distinct, chloroplast-containing bundle sheath cells are surrounded by two types of mesophyll cells. Smaller mesophyll cells containing many chloroplasts are arranged around the bundle sheath cells. Larger, spongy mesophyll cells, having fewer chloroplasts, are located between the smaller mesophyll cells and the epidermis. F. brownii has very low CO(2) compensation points at different O(2) levels, which is typical of C(4) plants, yet it does show about 4% inhibition of net photosynthesis by 21% O(2) at 30 degrees C. Protoplasts of the three photosynthetic leaf cell types were isolated according to relative differences in their buoyant densities. On a chlorophyll basis, the activities of phosphoenolpyruvate carboxylase and pyruvate, Pi dikinase (carboxylation phase of C(4) pathway) were highest in the larger mesophyll protoplasts, intermediate in the smaller mesophyll protoplasts, and lowest, but still present, in the bundle sheath protoplasts. In contrast, activities of ribulose 1,5-bisphosphate carboxylase, other C(3) cycle enzymes, and NADP-malic enzyme showed a reverse gradation, although there were significant activities of these enzymes in mesophyll cells. As indicated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the banding pattern of certain polypeptides of the total soluble proteins from the three cell types also supported the distribution pattern obtained by activity assays of these enzymes. Analysis of initial (14)C products in whole leaves and extrapolation of pulse-labeling curves to zero time indicated that about 80% of the CO(2) is fixed into C(4) acids (malate and aspartate), whereas about 20% of the CO(2) directly enters the C(3) cycle. This is consistent with the high activity of enzymes for CO(2) fixation by the C(4) pathway and the substantial activity of enzymes of the C(3) cycle in the mesophyll cells

Vitamin K-dependent carboxylases from non-hepatic tissues

NARCIS (Netherlands)

Vermeer, C.; Hendrix, H.; Daemen, M.

1982-01-01

The presence of vitamin K-dependent carboxylase was investigated in the microsomal fraction of 20 different types of bovine tissue. Except for muscle, veins, lymphocytes and bone membrane, carboxylase was found in all these preparations, albeit in varying amounts. No differences could be detected

Expression of phosphoenolpyruvate carboxykinase linked to chemoradiation susceptibility of human colon cancer cells

International Nuclear Information System (INIS)

Park, Ji-Won; Yang, Se Young; Kim, Dae Yong; Oh, Jae Hwan; Cho, Jae Youl; Yoo, Byong Chul; Kim, Seung Cheol; Kim, Won Ki; Hong, Jun Pyu; Kim, Kyung-Hee; Yeo, Hyun Yang; Lee, Jae Yong; Kim, M Sun; Kim, Jong Heon

2014-01-01

Resistance to 5-fluorouracil (5-FU) in patients with colorectal cancer prevents effective treatment and leads to unnecessary and burdensome chemotherapy. Therefore, prediction of 5-FU resistance is imperative. To identify the proteins linked to 5-FU resistance, two-dimensional gel electrophoresis-based proteomics was performed using the human colon cancer cell line SNU-C4R with induced 5-FU resistance. Proteins showing altered expression in SNU-C4R were identified by matrix-associated laser desorption/ionization–time-of-flight analysis, and their roles in susceptibility to 5-FU or radiation were evaluated in various cell lines by transfection of specific siRNA or creation of overexpression constructs. Changes in cellular signaling and expression of mitochondrial apoptotic factors were investigated by Western Blot analysis. A mitochondrial membrane potential probe (JC-1 dye) and a flow cytometry system were employed to determine the mitochondrial membrane potential. Finally, protein levels were determined by Western Blot analysis in tissues from 122 patients with rectal cancer to clarify whether each identified protein is a useful predictor of a chemoradiation response. We identified mitochondrial phosphoenolpyruvate carboxykinase (mPEPCK) as a candidate predictor of 5-FU resistance. PEPCK was downregulated in SNU-C4R compared with its parent cell line SNU-C4. Overexpression of mPEPCK did not significantly alter the susceptibility to either 5-FU or radiation. Suppression of mPEPCK led to a decrease in both the cellular level of phosphoenolpyruvate and the susceptibility to 5-FU and radiation. Furthermore, the cellular levels of phosphoenolpyruvate (an end product of PEPCK and a substrate of pyruvate kinase), phosphorylated AKT, and phosphorylated 4EBP1 were decreased significantly secondary to the mPEPCK suppression in SNU-C4. However, mPEPCK siRNA transfection induced changes in neither the mitochondrial membrane potential nor the expression levels of

The contribution of stored malate and citrate to the substrate requirements of metabolism of ripening peach (Prunus persica L. Batsch) flesh is negligible. Implications for the occurrence of phosphoenolpyruvate carboxykinase and gluconeogenesis.

Science.gov (United States)

Famiani, Franco; Farinelli, Daniela; Moscatello, Stefano; Battistelli, Alberto; Leegood, Richard C; Walker, Robert P

2016-04-01

The first aim of this study was to determine the contribution of stored malate and citrate to the substrate requirements of metabolism in the ripening flesh of the peach (Prunus persica L. Batsch) cultivar Adriatica. In the flesh, stored malate accumulated before ripening could contribute little or nothing to the net substrate requirements of metabolism. This was because there was synthesis and not dissimilation of malate throughout ripening. Stored citrate could potentially contribute a very small amount (about 5.8%) of the substrate required by metabolism when the whole ripening period was considered, and a maximum of about 7.5% over the latter part of ripening. The second aim of this study was to investigate why phosphoenolpyruvate carboxykinase (PEPCK) an enzyme utilised in gluconeogenesis from malate and citrate is present in peach flesh. The occurrence and localisation of enzymes utilised in the metabolism of malate, citrate and amino acids were determined in peach flesh throughout its development. Phosphoenolpyruvate carboxylase (essential for the synthesis of malate and citrate) was present in the same cells and at the same time as PEPCK and NADP-malic enzyme (both utilised in the dissimilation of malate and citrate). A hypothesis is presented to explain the presence of these enzymes and to account for the likely occurrence of gluconeogenesis. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Cloning and characterization of Escherichia coli DUF299: a bifunctional ADP-dependent kinase - Pi-dependent pyrophosphorylase from bacteria

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Burnell Jim N

2010-01-01

Full Text Available Abstract Background Phosphoenolpyruvate synthetase (PEPS; EC 2.7.9.2 catalyzes the synthesis of phosphoenolpyruvate from pyruvate in Escherichia coli when cells are grown on a three carbon source. It also catalyses the anabolic conversion of pyruvate to phosphoenolpyruvate in gluconeogenesis. A bioinformatics search conducted following the successful cloning and expression of maize leaf pyruvate, orthophosphate dikinase regulatory protein (PDRP revealed the presence of PDRP homologs in more than 300 bacterial species; the PDRP homolog was identified as DUF299. Results This paper describes the cloning and expression of both PEPS and DUF299 from E. coli and establishes that E. coli DUF299 catalyzes both the ADP-dependent inactivation and the Pi-dependent activation of PEPS. Conclusion This paper represents the first report of a bifunctional regulatory enzyme catalysing an ADP-dependent phosphorylation and a Pi-dependent pyrophosphorylation reaction in bacteria.

Characterization of Phosphoenolpyruvate Carboxykinase from Pineapple Leaves Ananas comosus (L.) Merr.

Science.gov (United States)

Daley, L S; Ray, T B; Vines, H M; Black, C C

1977-04-01

Phosphoenolpyruvate carboxykinase has been partially purified from pineapple (Ananas comosus [L.]) leaves. Specific activities obtained show it to be a major activity in this tissue. Above 15 C, the respective activation energies for decarboxylation and carboxylation are 13 and 12 kcal/mol. Below 15 C, there are discontinuities in Arrhenius plots with an associated large increase in activation energy. The adenine nucleotides are preferred to other nucleotides as substrates. The apparent Km values in the carboxylation direction are: ADP 0.13 mm, HCO(3) (-) 3.4 mm, and phosphoenolpyruvate 5 mm. In the decarboxylation direction, the apparent Km values are: ATP 0.02 mm, ADP 0.05 mm, and oxaloacetate 0.4 mm. The decarboxylation activity had an almost equal velocity with either ADP or ATP. The pH optima are between 6.8 and 7. Inhibition of the carboxylation reaction by ATP, pyruvate, and carbonic anhydrase was demonstrated. Decarboxylase specific activities are over twice carboxylation activities. The data support a model in which phosphoenolpyruvate carboxykinase is of physiological significance only during the light period and then only as a decarboxylase.

Studies of vitamin K-dependent carboxylase

International Nuclear Information System (INIS)

Wood, G.M.

1986-01-01

Carboxylase was studied in detergent solubilized rat liver microsomes, using the peptide substrate Phe-Leu-[γ- 3 H]-Glu-Glu-Leu. Cleavage of the γ-C-H bond in Glu was measured as the release of 3 H from this peptide to water, carboxylation was measured as the incorporation of H 14 CO 3 -into the peptide, and KO formation was measured by an HPLC assay. All three products could be measured simultaneously, and this system was used to examine the effects of cyanide, manganese, tetrachloropyridinol, and Boc-SerP-SerP-Leu-OMe on the separate steps of the carboxylase reaction. Vitamin K-epoxide formation was studied separately from the other reactions, and it was found that in the absence of a Glu-containing substrate, carboxylase catalyzed the uncoupled formation of KO from KH 2 and O 2 . The stoichiometry of product formation (GLa, KO, and γ-protons) was measured, and the results obtained were all in agreement with the values predicted from the proposed mechanism. When all of the substrates were saturating, the stoichiometry of γ-C-H bond cleavage, carboxylation, and KO formation was 1:1:1

Use of Carbon -14 and Phosphorus -32 to study phosphorus acquisition efficiency in crop plants

International Nuclear Information System (INIS)

Pandey, Renu; Vengavasi, Krishnapriya

2017-01-01

Low bioavailability of phosphorus (P) in soils is one of the major limiting factors to crop production throughout the world. P nutrition improves yield, with significant influences on the above- (leaf area, photosynthesis, dry matter accumulation, leaf P content) and below-ground (root morphology, exudation, symbiosis) processes (Pandey et al., 2015). Plants, however, are known to possess potential adaptive mechanisms at morphological, physiological, biochemical, and molecular levels to overcome P deficiency. Such adaptive mechanisms mainly include an increase in total root length and root hair growth (Pandey et al., unpublished), enhancement of organic acids (Vengavasi and Pandey, 2016a, b), acid phosphatase (Pandey, 2006) and ribonuclease (RNase) secretion into the rhizosphere (Hocking, 2001), increase in expression of proteins such as phosphatase, inorganic phosphate (Pi) transporter, RNase and phosphoenolpyruvate carboxylase (PEPcase) in plant tissues (Ragothama, 1999). Of all the above, rhizosphere acidification provides maximum exploration of soil volume around the rooting zone leading to conversion of non-available nutrients into available forms thus, resulting in enhanced uptake efficiency

Phosphoenolpyruvate-dependent protein kinase enzyme I of Streptococcus faecalis: purification and properties of the enzyme and characterization of its active center

International Nuclear Information System (INIS)

Alpert, C.A.; Frank, R.; Stueber, K.D.; Deutscher, J.; Hengstenberg, W.

1985-01-01

Enzyme I, the phosphoenolpyruvate:protein phosphotransferase (EC 2.7.3.9), which is part of the bacterial phosphoenolpyruvate-(PEP) dependent phosphotransferase system, has been purified from Streptococcus faecalis by using a large-scale preparation. Size exclusion chromatography revealed a molecular weight of 140,000. On sodium dodecyl sulfate gels, enzyme I gave one band with a molecular weight of 70,000, indicating that enzyme I consists of two identical subunits. The first 59 amino acids of the amino-terminal part of the protein have been sequenced. It showed some similarities with enzyme I of Salmonella typhimurium. The active center of enzyme I has also been determined. After phosphorylation with [ 32 P]PEP, the enzyme was cleaved by using different proteases. Labeled peptides were isolated by high-performance liquid chromatography on a reversed-phase column. The amino acid composition or amino acid sequence of the peptides has been determined. The largest labeled peptide was obtained with Lys-C protease and had the following sequence: -Ala-Phe-Val-Thr-Asp-Ile-Gly- Gly-Arg-Thr-Ser-His*-Ser-Ala-Ile-Met-Ala-Arg-Ser-Leu-Glu-Ile-Pro-Ala- Ile-Val-Gly-Thr-Lys-. It has previously been shown that the phosphoryl group is bound to the N-3 position of a histidyl residue in phosphorylated enzyme I. The single His in position 12 of the above peptide must therefore carry the phosphoryl group

Characterization of Phosphoenolpyruvate Carboxykinase from Pineapple Leaves Ananas comosus (L.) Merr. 1

Science.gov (United States)

Daley, Laurence S.; Ray, Thomas B.; Vines, H. Max; Black, Clanton C.

1977-01-01

Phosphoenolpyruvate carboxykinase has been partially purified from pineapple (Ananas comosus [L.]) leaves. Specific activities obtained show it to be a major activity in this tissue. Above 15 C, the respective activation energies for decarboxylation and carboxylation are 13 and 12 kcal/mol. Below 15 C, there are discontinuities in Arrhenius plots with an associated large increase in activation energy. The adenine nucleotides are preferred to other nucleotides as substrates. The apparent Km values in the carboxylation direction are: ADP 0.13 mm, HCO3- 3.4 mm, and phosphoenolpyruvate 5 mm. In the decarboxylation direction, the apparent Km values are: ATP 0.02 mm, ADP 0.05 mm, and oxaloacetate 0.4 mm. The decarboxylation activity had an almost equal velocity with either ADP or ATP. The pH optima are between 6.8 and 7. Inhibition of the carboxylation reaction by ATP, pyruvate, and carbonic anhydrase was demonstrated. Decarboxylase specific activities are over twice carboxylation activities. The data support a model in which phosphoenolpyruvate carboxykinase is of physiological significance only during the light period and then only as a decarboxylase. PMID:16659905

Photosynthetic carbon fixation characteristics of fruiting structures of Brassica campestris L

International Nuclear Information System (INIS)

Singal, H.R.; Sheoran, I.S.; Singh, R.

1987-01-01

Activities of key enzymes of the Calvin cycle and C 4 metabolism, rates of CO 2 fixation, and the initial products of photosynthetic 14 CO 2 fixation were determined in the podwall, seed coat (fruiting structures), and the subtending leaf (leaf below a receme) of Brassica campestris L. cv Toria. Compared to activities of ribulose-1,5-bisphosphate carboxylase and other Calvin cycle enzymes, e.g. NADP-glyceraldehyde-3-phosphate-dehydrogenase and ribulose-5-phosphate kinase, the activities of phosphoenol pyruvate carboxylase and other enzymes of C 4 metabolism, viz. NADP-malate dehydrogenase, NADP-malic enzyme, glutamate pyruvate transaminase, and glutamate oxaloacetate transaminase, were generally much higher in seed than in podwall and leaf. Podwall and leaf were comparable to each other. Pulse-chase experiments showed that in seed the major product of 14 CO 2 assimilation was malate (in short time), whereas in podwall and leaf, the label initially appeared in 3-PGA. With time, the label moved to sucrose. In contrast to legumes, Brassica pods were able to fix net CO 2 during light. However, respiratory losses were very high during the dark period

Short-term acclimation to warmer temperatures accelerates leaf carbon exchange processes across plant types.

Science.gov (United States)

Smith, Nicholas G; Dukes, Jeffrey S

2017-11-01

While temperature responses of photosynthesis and plant respiration are known to acclimate over time in many species, few studies have been designed to directly compare process-level differences in acclimation capacity among plant types. We assessed short-term (7 day) temperature acclimation of the maximum rate of Rubisco carboxylation (V cmax ), the maximum rate of electron transport (J max ), the maximum rate of phosphoenolpyruvate carboxylase carboxylation (V pmax ), and foliar dark respiration (R d ) in 22 plant species that varied in lifespan (annual and perennial), photosynthetic pathway (C 3 and C 4 ), and climate of origin (tropical and nontropical) grown under fertilized, well-watered conditions. In general, acclimation to warmer temperatures increased the rate of each process. The relative increase in different photosynthetic processes varied by plant type, with C 3 species tending to preferentially accelerate CO 2 -limited photosynthetic processes and respiration and C 4 species tending to preferentially accelerate light-limited photosynthetic processes under warmer conditions. R d acclimation to warmer temperatures caused a reduction in temperature sensitivity that resulted in slower rates at high leaf temperatures. R d acclimation was similar across plant types. These results suggest that temperature acclimation of the biochemical processes that underlie plant carbon exchange is common across different plant types, but that acclimation to warmer temperatures tends to have a relatively greater positive effect on the processes most limiting to carbon assimilation, which differ by plant type. The acclimation responses observed here suggest that warmer conditions should lead to increased rates of carbon assimilation when water and nutrients are not limiting. © 2017 John Wiley & Sons Ltd.

Mitochondrial storage form of acetyl CoA carboxylase in fasted and alloxan diabetic rats

International Nuclear Information System (INIS)

Roman-Lopez, C.R.; Allred, J.B.

1986-01-01

Sodium dodecyl sulfate-denatured biotinyl proteins will bind [ 14 C]methyl avidin which remains bound through polyacrylamide gel electrophoresis. The method has been used to demonstrate the presence of two high molecular weight subunit forms of acetyl CoA carboxylase in rat liver cytoplasm, both of which are precipitated by antibody to purifed rat liver acetyl CoA carboxylase prepared from sheep serum. Rat liver mitochondria contained five distinct biotinyl protein subunits, the two largest of which have been identified as acetyl CoA carboxylase subunits on the basis of precipitation by anti-acetyl CoA carboxylase antibody. The small quantity of acetyl CoA carboxylase associated with rat liver microsomes could be attributed to cytoplasmic contamination. The binding of radioactive avidin is sufficiently tight to use as a measure of the quantity of acetyl CoA carboxylase. The quantity and activity of the cytoplasmic enzyme was reduced in fasted and in alloxan diabetic rats compared to that in fed controls but the quantity of the enzyme associated with isolated mitochondria was not reduced. The results indicate that there is a mitochondrial storage form of acetyl CoA carboxylase

Improvement of Escherichia coli production strains by modification of the phosphoenolpyruvate:sugar phosphotransferase system

Directory of Open Access Journals (Sweden)

Gosset Guillermo

2005-05-01

Full Text Available Abstract The application of metabolic engineering in Escherichia coli has resulted in the generation of strains with the capacity to produce metabolites of commercial interest. Biotechnological processes with these engineered strains frequently employ culture media containing glucose as the carbon and energy source. In E. coli, the phosphoenolpyruvate:sugar phosphotransferase system (PTS transports glucose when this sugar is present at concentrations like those used in production fermentations. This protein system is involved in phosphoenolpyruvate-dependent sugar transport, therefore, its activity has an important impact on carbon flux distribution in the phosphoenolpyruvate and pyruvate nodes. Furthermore, PTS has a very important role in carbon catabolite repression. The properties of PTS impose metabolic and regulatory constraints that can hinder strain productivity. For this reason, PTS has been a target for modification with the purpose of strain improvement. In this review, PTS characteristics most relevant to strain performance and the different strategies of PTS modification for strain improvement are discussed. Functional replacement of PTS by alternative phosphoenolpyruvate-independent uptake and phosphorylation activities has resulted in significant improvements in product yield from glucose and productivity for several classes of metabolites. In addition, inactivation of PTS components has been applied successfully as a strategy to abolish carbon catabolite repression, resulting in E. coli strains that use more efficiently sugar mixtures, such as those obtained from lignocellulosic hydrolysates.

Bibliography of reviews and methods of photosynthesis-90

Czech Academy of Sciences Publication Activity Database

Šesták, Zdeněk; Čatský, Jiří

2006-01-01

Roč. 44, č. 4 (2006), s. 627-640 ISSN 0300-3604 Institutional research plan: CEZ:AV0Z50380511 Keywords : phosphoenolpyruvate carboxylase * water use efficiency * transpiration Subject RIV: ED - Physiology Impact factor: 0.782, year: 2006

Spectroscopic studies of phosphoenolpyruvate carboxykinase from Mycobacterium tuberculosis

Czech Academy of Sciences Publication Activity Database

Bednárová, Lucie; Machová, Iva; Snášel, Jan; Dostál, Jiří; Hubálek, Martin; Pichová, Iva

2015-01-01

Roč. 22, č. 1 (2015), s. 16 ISSN 1211-5894. [Discussions in Structural Molecular Biology. Annual Meeting of the Czech Society for Structural Biology /13./. 19.03.2015-21.03.2015, Nové Hrady] R&D Projects: GA MŠk LO1302 Institutional support: RVO:61388963 Keywords : phosphoenolpyruvate carboxykinase * structure * thiol * Raman spectroscopy * circular dichroism Subject RIV: CE - Biochemistry

Escherichia coli Phosphoenolpyruvate-Dependent Phosphotransferase System. Functional Asymmetry in Enzyme I Subunits Demonstrated by Reaction with 3-Bromopyruvate

NARCIS (Netherlands)

Hoeve-Duurkens, Ria ten; Robillard, George T.

1984-01-01

In the bacterial phosphoenolpyruvate-dependent sugar transport systems, enzyme I (EI) is responsible for the initial reaction step which is the transfer of the phosphoryl group from phosphoenolpyruvate to a cytoplasmic phosphocarrier protein (HPr). The inactivation of enzyme I by the substrate

Two phosphoenolpyruvate carboxykinases coexist in the Crassulacean Acid Metabolism plant Ananas comosus. Isolation and characterization of the smaller 65 kDa form.

Science.gov (United States)

Martín, Mariana; Rius, Sebastián Pablo; Podestá, Florencio Esteban

2011-06-01

Two phosphoenolpyruvate carboxykinase (PEPCK, EC 4.1.1.49) isoforms of 74 and 65 kDa were found to coexist in vivo in pineapple leaves, a constitutive Crassulacean Acid Metabolism plant. The 65 kDa form was not the result of proteolytic cleavage of the larger form since extraction methods reported to prevent PEPCK proteolysis in other plant tissues failed to yield a single immunoreactive PEPCK polypeptide in leaf extracts. In this work, the smaller form of 65 kDa was purified to homogeneity and physically and kinetically characterized and showed parameters compatible with a fully active enzyme. The specific activity was nearly twice higher for decarboxylation of oxaloacetate when compared to carboxylation of phosphoenolpyruvate. Kinetic parameters fell within the range of those estimated for other plant PEPCKs. Its activity was affected by several metabolites, as shown by inhibition by 3-phosphoglycerate, citrate, malate, fructose-1,6-bisphosphate, l-asparagine and activation of the decarboxylating activity by succinate. A break in the Arrhenius plot at about 30°C indicates that PEPCK structure is responsive to changes in temperature. The results indicate that pineapple leaves contain two PEPCK forms. The biochemical characterization of the smaller isoform performed in this work suggests that it could participate in both carbon and nitrogen metabolism in vivo by acting as a decarboxylase. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Nitric oxide inhibits glycogen synthesis in isolated rat hepatocytes

NARCIS (Netherlands)

Sprangers, F.; Sauerwein, H. P.; Romijn, J. A.; van Woerkom, G. M.; Meijer, A. J.

1998-01-01

There is increasing evidence for the existence of intrahepatic regulation of glucose metabolism by Kupffer cell products. Nitric oxide (NO) is known to inhibit gluconeogenic flux through pyruvate carboxylase and phosphoenolpyruvate carboxykinase. However, NO may also influence glucose metabolism at

Molecular Cloning and Characterization of Two Genes for the Biotin Carboxylase and Carboxyltransferase Subunits of Acetyl Coenzyme A Carboxylase in Myxococcus xanthus

OpenAIRE

Kimura, Yoshio; Miyake, Rina; Tokumasu, Yushi; Sato, Masayuki

2000-01-01

We have cloned a DNA fragment from a genomic library of Myxococcus xanthus using an oligonucleotide probe representing conserved regions of biotin carboxylase subunits of acetyl coenzyme A (acetyl-CoA) carboxylases. The fragment contained two open reading frames (ORF1 and ORF2), designated the accB and accA genes, capable of encoding a 538-amino-acid protein of 58.1 kDa and a 573-amino-acid protein of 61.5 kDa, respectively. The protein (AccA) encoded by the accA gene was strikingly similar t...

A Patient With Pyruvate Carboxylase Deficiency and Nemaline Rods on Muscle Biopsy

DEFF Research Database (Denmark)

Unal, Ozlem; Orhan, Diclehan; Ostergaard, Elsebet

2013-01-01

Nemaline rods are the pathologic hallmark of nemaline myopathy, but they have also been described as a secondary phenomenon in a variety of other disorders. Nemaline rods have not been reported in pyruvate carboxylase deficiency before. Here we present a patient with pyruvate carboxylase deficiency...

Differences between magnesium-activated and manganese-activated pyruvate kinase from the muscle of Concholepas concholepas.

Science.gov (United States)

González, R; Carvajal, N; Morán, A

1984-01-01

In contrast to the Mg2+-activated enzyme, in the presence of Mn2+ pyruvate kinase exhibits hyperbolic kinetics with respect to the substrate phosphoenolpyruvate and is insensitive to fructose 1,6-biphosphate, phenylalanine and alanine. However, with both metal activated species inhibition by excess ADP is observed. In contrast with Mg2+, which affords significant protection against inactivation caused by 5,5'-dithiobis (2-nitrobenzoic acid), the rate of inactivation by this reagent is increased in the presence of Mn2+. Differences in conformational changes induced by combination of pyruvate kinase with Mg2+ or Mn2+ were indicated by u.v. difference spectra.

Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

Energy Technology Data Exchange (ETDEWEB)

Ferreira, R.M.B. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia]|[Universidade Nova de Lisboa, Oeiras (Portugal). Instituto de Tecnologia Quimica e Biologica; Franco, E.; Teixeira, A.R.N. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia

1996-08-15

The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of {sup 35}S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author).

Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

International Nuclear Information System (INIS)

Ferreira, R.M.B.; Universidade Nova de Lisboa, Oeiras; Franco, E.; Teixeira, A.R.N.

1996-01-01

The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of 35 S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author)

Transgene silencing of sucrose synthase in alfalfa (Medicago sativa L.) stem vascular tissue suggests a role for invertase in cell wall cellulose synthesis

Science.gov (United States)

Alfalfa (Medicago sativa L.) plants were transformed with two constructs: (1) a truncated phosphoenolpyruvate carboxylase promoter isolated from alfalfa nodules (PEPC-4) fused to GUS; and (2) PEPC-4 fused with sucrose synthase (SUS) isolated from alfalfa nodules. Histochemical staining for GUS in st...

Structural Analysis of Substrate, Reaction Intermediate, and Product Binding in Haemophilus influenzae Biotin Carboxylase

Science.gov (United States)

Broussard, Tyler C.; Pakhomova, Svetlana; Neau, David B.; Bonnot, Ross; Waldrop, Grover L.

2015-01-01

Acetyl-CoA carboxylase catalyzes the first and regulated step in fatty acid synthesis. In most Gram-negative and Gram-positive bacteria, the enzyme is composed of three proteins: biotin carboxylase, a biotin carboxyl carrier protein (BCCP), and carboxyltransferase. The reaction mechanism involves two half-reactions with biotin carboxylase catalyzing the ATP-dependent carboxylation of biotin-BCCP in the first reaction. In the second reaction, carboxyltransferase catalyzes the transfer of the carboxyl group from biotin-BCCP to acetyl-CoA to form malonyl-CoA. In this report, high-resolution crystal structures of biotin carboxylase from Haemophilus influenzae were determined with bicarbonate, the ATP analogue AMPPCP; the carboxyphosphate intermediate analogues, phosphonoacetamide and phosphonoformate; the products ADP and phosphate; and the carboxybiotin analogue N1′-methoxycarbonyl biotin methyl ester. The structures have a common theme in that bicarbonate, phosphate, and the methyl ester of the carboxyl group of N1′-methoxycarbonyl biotin methyl ester all bound in the same pocket in the active site of biotin carboxylase and as such utilize the same set of amino acids for binding. This finding suggests a catalytic mechanism for biotin carboxylase in which the binding pocket that binds tetrahedral phosphate also accommodates and stabilizes a tetrahedral dianionic transition state resulting from direct transfer of CO2 from the carboxyphosphate intermediate to biotin. PMID:26020841

Dorsoventral variations in dark chilling effects on photosynthesis and stomatal function in Paspalum dilatatum leaves.

Science.gov (United States)

Soares-Cordeiro, Ana Sofia; Driscoll, Simon P; Arrabaça, Maria Celeste; Foyer, Christine H

2011-01-01

The effects of dark chilling on the leaf-side-specific regulation of photosynthesis were characterized in the C(4) grass Paspalum dilatatum. CO(2)- and light-response curves for photosynthesis and associated parameters were measured on whole leaves and on each leaf side independently under adaxial and abaxial illumination before and after plants were exposed to dark chilling for one or two consecutive nights. The stomata closed on the adaxial sides of the leaves under abaxial illumination and no CO(2) uptake could be detected on this surface. However, high rates of whole leaf photosynthesis were still observed because CO(2) assimilation rates were increased on the abaxial sides of the leaves under abaxial illumination. Under adaxial illumination both leaf surfaces contributed to the inhibition of whole leaf photosynthesis observed after one night of chilling. After two nights of chilling photosynthesis remained inhibited on the abaxial side of the leaf but the adaxial side had recovered, an effect related to increased maximal ribulose-1,5-bisphosphate carboxylation rates (V(cmax)) and enhanced maximal electron transport rates (J(max)). Under abaxial illumination, whole leaf photosynthesis was decreased only after the second night of chilling. The chilling-dependent inhibition of photosynthesis was located largely on the abaxial side of the leaf and was related to decreased V(cmax) and J(max), but not to the maximal phosphoenolpyruvate carboxylase carboxylation rate (V(pmax)). Each side of the leaf therefore exhibits a unique sensitivity to stress and recovery. Side-specific responses to stress are related to differences in the control of enzyme and photosynthetic electron transport activities.

Abscisic acid as a factor in regulation of photosynthetic carbon metabolism of pea seedlings

Directory of Open Access Journals (Sweden)

Maria Faltynowicz

2014-01-01

Full Text Available The influence of abscisic acid (ABA on carbon metabolism and the activity of ribulosebisphosphate (RuBP and phosphoenolpyruvate (PEP carboxylases in 8-day-old pea seedlings was investigated. It was endeavoured to correlate the changes observed in metabolic processes with the endogenous ABA level. In plants treated with ABA incorporation of labeled carbon into sucrose, glucose, fructose and sugar phosphates was depressed, while 14C incorporation into starch, ribulose and malic acid was enhanced. The activity of RuBP carboxylase was considerably lowered, whereas that of PEP carboxylase was slightly increased. It is considered that inhibition of photosynthesis due to the action of ABA is caused to a great extent by the obstruction of the C-3 pathway and reduced activity of RuBP carboxylase, whereas (β-carboxylation was not blocked.

Bibliography of reviews and methods of photosynthesis — 89

Czech Academy of Sciences Publication Activity Database

Šesták, Zdeněk; Čatský, Jiří

2005-01-01

Roč. 43, č. 4 (2005), s. 621-640 ISSN 0300-3604 R&D Projects: GA MŠk LN00A081 Institutional research plan: CEZ:AV0Z50380511 Keywords : phosphoenolpyruvate carboxylase * photosynthetically active radiation * transpiration Subject RIV: EF - Botanics Impact factor: 0.810, year: 2005

Erythrocyte pyruvate kinase deficiency in the Ohio Amish: origin and characterization of the mutant enzyme.

OpenAIRE

Muir, W A; Beutler, E; Wasson, C

1984-01-01

We have identified eight individuals in an Amish population in Geauga County, Ohio, who have a congenital hemolytic anemia and red cell pyruvate kinase (PK) deficiency. The mutant enzyme is a low Km phosphoenolpyruvate (PEP) variant associated with a slower (77.5% of normal) electrophoretic mobility in starch gel. Because of the high consanguinity in this population, we assume the affected individuals are homozygous for the mutant gene. Genealogical records allow us to trace all eight cases b...

Interaction of renin-angiotensin system and adenosine monophosphate-activated protein kinase signaling pathway in renal carcinogenesis of uninephrectomized rats.

Science.gov (United States)

Yang, Ke-Ke; Sui, Yi; Zhou, Hui-Rong; Zhao, Hai-Lu

2017-05-01

Renin-angiotensin system and adenosine monophosphate-activated protein kinase signaling pathway both play important roles in carcinogenesis, but the interplay of renin-angiotensin system and adenosine monophosphate-activated protein kinase in carcinogenesis is not clear. In this study, we researched the interaction of renin-angiotensin system and adenosine monophosphate-activated protein kinase in renal carcinogenesis of uninephrectomized rats. A total of 96 rats were stratified into four groups: sham, uninephrectomized, and uninephrectomized treated with angiotensin-converting enzyme inhibitor or angiotensin receptor blocker. Renal adenosine monophosphate-activated protein kinase and its downstream molecule acetyl coenzyme A carboxylase were detected by immunohistochemistry and western blot at 10 months after uninephrectomy. Meanwhile, we examined renal carcinogenesis by histological transformation and expressions of Ki67 and mutant p53. During the study, fasting lipid profiles were detected dynamically at 3, 6, 8, and 10 months. The results indicated that adenosine monophosphate-activated protein kinase expression in uninephrectomized rats showed 36.8% reduction by immunohistochemistry and 89.73% reduction by western blot. Inversely, acetyl coenzyme A carboxylase expression increased 83.3% and 19.07% in parallel to hyperlipidemia at 6, 8, and 10 months. The histopathology of carcinogenesis in remnant kidneys was manifested by atypical proliferation and carcinoma in situ, as well as increased expressions of Ki67 and mutant p53. Intervention with angiotensin-converting enzyme inhibitor or angiotensin receptor blocker significantly prevented the inhibition of adenosine monophosphate-activated protein kinase signaling pathway and renal carcinogenesis in uninephrectomized rats. In conclusion, the novel findings suggest that uninephrectomy-induced disturbance in adenosine monophosphate-activated protein kinase signaling pathway resulted in hyperlipidemia and

The calcium-dependent protein kinase RcCDPK2 phosphorylates sucrose synthase at Ser11 in developing castor oil seeds.

Science.gov (United States)

Fedosejevs, Eric T; Gerdis, Suzanne A; Ying, Sheng; Pyc, Michal; Anderson, Erin M; Snedden, Wayne A; Mullen, Robert T; She, Yi-Min; Plaxton, William C

2016-10-15

Imported sucrose is cleaved by sucrose synthase (SUS) as a critical initial reaction in the biosynthesis of storage end-products by developing seeds. Although SUS is phosphorylated at a conserved seryl residue by an apparent CDPK (Ca 2+ -dependent protein kinase) in diverse plant tissues, the functions and mechanistic details of this process remain obscure. Thus, the native CDPK that phosphorylates RcSUS1 (Ricinus communis SUS1) at Ser 11 in developing COS (castor oil seeds) was highly purified and identified as RcCDPK2 by MS/MS. Purified RcSUS1-K (-kinase) and heterologously expressed RcCDPK2 catalyzed Ca 2+ -dependent Ser 11 phosphorylation of RcSUS1 and its corresponding dephosphopeptide, while exhibiting a high affinity for free Ca 2+ ions [K 0.5 (Ca 2+ ) < 0.4 µM]. RcSUS1-K activity, RcCDPK2 expression, and RcSUS1 Ser 11 phosphorylation peaked during early COS development and then declined in parallel. The elimination of sucrose import via fruit excision triggered RcSUS1 dephosphorylation but did not alter RcSUS1-K activity, suggesting a link between sucrose signaling and posttranslational RcCDPK2 control. Both RcCDPK2-mCherry and RcSUS1-EYFP co-localized throughout the cytosol when transiently co-expressed in tobacco suspension cells, although RcCDPK2-mCherry was also partially localized to the nucleus. Subcellular fractionation revealed that ∼20% of RcSUS1-K activity associates with microsomal membranes in developing COS, as does RcSUS1. In contrast with RcCDPK1, which catalyzes inhibitory phosphorylation of COS bacterial-type phosphoenolpyruvate carboxylase at Ser 451 , RcCDPK2 exhibited broad substrate specificity, a wide pH-activity profile centered at pH 8.5, and insensitivity to metabolite effectors or thiol redox status. Our combined results indicate a possible link between cytosolic Ca 2+ -signaling and the control of photosynthate partitioning during COS development. © 2016 The Author(s); published by Portland Press Limited on behalf of the

Isolation, identification, and synthesis of 2-carboxyarabinitol 1-phosphate, a diurnal regulator of ribulase-bisphosphate carboxylase activity

International Nuclear Information System (INIS)

Berry, J.A.; Lorimer, G.H.; Pierce, J.; Seemann, J.R.; Meek, J.; Freas, S.

1987-01-01

The diurnal change in activity of ribulose 1,5-bisphosphate (Rbu-1,5-P 2 ) carboxylase [3-phospho-D-glycerate carboxy-lyase (dimerizing); EC 4.1.1.39] of leaves of Phaseolus vulgaris is regulated (in part) by mechanisms that control the level of an endogenous inhibitor that binds tightly to the activated (carbamoylated) form of Rbu-1,5-P 2 carboxylase. This inhibitor was extracted from leaves and copurified with the Rbu-1,5-P 2 carboxylase of the leaves. Further purification by ion-exchange chromatography, adsorption to purified Rbu-1,5-P 2 carboxylase, barium precipitation, and HPLC separation yielded a phosphorylated compound that was a strong inhibitor of Rbu-1,5-P 2 carboxylase. The compound was analyzed by GC/MS, 13 C NMR, and 1 H NMR and shown to be 2-carboxyarabinitol 1-phosphate [(2-C-phosphohydroxymethyl)-D-ribonic acid]. The structure of the isolated compound differs from the Rbu-1,5-P 2 carboxylase transition-state analogue 2-carboxyarabinitol 1,5-bisphosphate only by the lack of the C-5 phosphate group. This difference results in a higher binding constant for the monophosphate compared with the bisphosphate. The less tightly bound compound acts in a light-dependent, reversible regulation of Rbu-1,5-P 2 carboxylase activity in vivo

Purification and characterization of acetone carboxylase from Xanthobacter strain Py2

OpenAIRE

Sluis, Miriam K.; Ensign, Scott A.

1997-01-01

Acetone metabolism in the aerobic bacterium Xanthobacter strain Py2 proceeds by a carboxylation reaction forming acetoacetate as the first detectable product. In this study, acetone carboxylase, the enzyme catalyzing this reaction, has been purified to homogeneity and characterized. Acetone carboxylase was comprised of three polypeptides with molecular weights of 85,300, 78,300, and 19,600 arranged in an α2β2γ2 quaternary structure. The carboxylation of acetone was coupled to the hydrolysis o...

Determination of gluconeogenesis in vivo with 14C-labeled substrates

International Nuclear Information System (INIS)

Katz, J.

1985-01-01

A mitochondrial model of gluconeogenesis and the tricarboxylic acid cycle, where pyruvate is metabolized via pyruvate carboxylase and pyruvate dehydrogenase, and pyruvate kinase is examined. The effect of the rate of tricarboxylic acid flux and the rates of the three reactions of pyruvate metabolism on the labeling patterns from [ 14 C]pyruvate and [ 14 C]acetate are analyzed. Expressions describing the specific radioactivities and 14 C distribution in glucose as a function of these rates are derived. Specific radioactivities and isotopic patterns depend markedly on the ratio of the rates of pyruvate carboxylation and decarboxylation to the rate of citrate synthesis, but the effect of phosphoenolpyruvate hydrolysis is minor. The effects of these rates on 1) specific radioactivity of phosphoenolpyruvate, 2) labeling pattern in glucose, and 3) contribution of pyruvate, acetyl-coenzyme A, and CO 2 to glucose carbon are illustrated. To determine the contribution of lactate or alanine to gluconeogenesis, experiments with two compounds labeled in different carbons are required. Methods in current use to correct for the dilution of 14 C in gluconeogenesis from [ 14 C]pyruvate are shown to be erroneous. The experimental design and techniques to determine gluconeogenesis from 14 C-labeled precursors are presented and illustrated with numerical examples

Conserved and divergent rhythms of crassulacean acid metabolism-related and core clock gene expression in the cactus Opuntia ficus-indica.

Science.gov (United States)

Mallona, Izaskun; Egea-Cortines, Marcos; Weiss, Julia

2011-08-01

The cactus Opuntia ficus-indica is a constitutive Crassulacean acid metabolism (CAM) species. Current knowledge of CAM metabolism suggests that the enzyme phosphoenolpyruvate carboxylase kinase (PPCK) is circadian regulated at the transcriptional level, whereas phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH), NADP-malic enzyme (NADP-ME), and pyruvate phosphate dikinase (PPDK) are posttranslationally controlled. As little transcriptomic data are available from obligate CAM plants, we created an expressed sequence tag database derived from different organs and developmental stages. Sequences were assembled, compared with sequences in the National Center for Biotechnology Information nonredundant database for identification of putative orthologs, and mapped using Kyoto Encyclopedia of Genes and Genomes Orthology and Gene Ontology. We identified genes involved in circadian regulation and CAM metabolism for transcriptomic analysis in plants grown in long days. We identified stable reference genes for quantitative polymerase chain reaction and found that OfiSAND, like its counterpart in Arabidopsis (Arabidopsis thaliana), and OfiTUB are generally appropriate standards for use in the quantification of gene expression in O. ficus-indica. Three kinds of expression profiles were found: transcripts of OfiPPCK oscillated with a 24-h periodicity; transcripts of the light-active OfiNADP-ME and OfiPPDK genes adapted to 12-h cycles, while transcript accumulation patterns of OfiPEPC and OfiMDH were arrhythmic. Expression of the circadian clock gene OfiTOC1, similar to Arabidopsis, oscillated with a 24-h periodicity, peaking at night. Expression of OfiCCA1 and OfiPRR9, unlike in Arabidopsis, adapted best to a 12-h rhythm, suggesting that circadian clock gene interactions differ from those of Arabidopsis. Our results indicate that the evolution of CAM metabolism could be the result of modified circadian regulation at both the transcriptional and posttranscriptional

Conserved and Divergent Rhythms of Crassulacean Acid Metabolism-Related and Core Clock Gene Expression in the Cactus Opuntia ficus-indica1[C][W

Science.gov (United States)

Mallona, Izaskun; Egea-Cortines, Marcos; Weiss, Julia

2011-01-01

The cactus Opuntia ficus-indica is a constitutive Crassulacean acid metabolism (CAM) species. Current knowledge of CAM metabolism suggests that the enzyme phosphoenolpyruvate carboxylase kinase (PPCK) is circadian regulated at the transcriptional level, whereas phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH), NADP-malic enzyme (NADP-ME), and pyruvate phosphate dikinase (PPDK) are posttranslationally controlled. As little transcriptomic data are available from obligate CAM plants, we created an expressed sequence tag database derived from different organs and developmental stages. Sequences were assembled, compared with sequences in the National Center for Biotechnology Information nonredundant database for identification of putative orthologs, and mapped using Kyoto Encyclopedia of Genes and Genomes Orthology and Gene Ontology. We identified genes involved in circadian regulation and CAM metabolism for transcriptomic analysis in plants grown in long days. We identified stable reference genes for quantitative polymerase chain reaction and found that OfiSAND, like its counterpart in Arabidopsis (Arabidopsis thaliana), and OfiTUB are generally appropriate standards for use in the quantification of gene expression in O. ficus-indica. Three kinds of expression profiles were found: transcripts of OfiPPCK oscillated with a 24-h periodicity; transcripts of the light-active OfiNADP-ME and OfiPPDK genes adapted to 12-h cycles, while transcript accumulation patterns of OfiPEPC and OfiMDH were arrhythmic. Expression of the circadian clock gene OfiTOC1, similar to Arabidopsis, oscillated with a 24-h periodicity, peaking at night. Expression of OfiCCA1 and OfiPRR9, unlike in Arabidopsis, adapted best to a 12-h rhythm, suggesting that circadian clock gene interactions differ from those of Arabidopsis. Our results indicate that the evolution of CAM metabolism could be the result of modified circadian regulation at both the transcriptional and posttranscriptional

Pyruvate carboxylase is expressed in human skeletal muscle

DEFF Research Database (Denmark)

Minet, Ariane D; Gaster, Michael

2010-01-01

Pyruvate carboxylase (PC) is a mitochondrial enzyme that catalyses the carboxylation of pyruvate to oxaloacetate thereby allowing supplementation of citric acid cycle intermediates. The presence of PC in skeletal muscle is controversial. We report here, that PC protein is easily detectable...

Photosynthetic plasticity in Flaveria brownii: Growth irradiance and the expression of C4 photosynthesis

International Nuclear Information System (INIS)

Cheng, Shuhua; Moore, B.D.; Wu, Jingrui; Edwards, G.E.; Ku, M.S.B.

1989-01-01

Photosynthesis was examined in leaves of Flaveria brownii A. M. Powell, grown under either 14% or 100% full sunlight. In leaves of high light grown plants, the CO 2 compensation point and the inhibition of photosynthesis by 21% O 2 were significantly lower, while activities of ribulose 1,5-bisphosphate carboxylase/oxygenase and various C 4 cycle enzymes were considerably higher than those in leaves grown in low light. Both the CO 2 compensation point and the degree of O 2 inhibition of apparent photosynthesis were relatively insensitive to the light intensity used during measurements with plants from either growth conditions. Partitioning of atmospheric CO 2 between Rubisco of the C 3 pathway and phosphoenolpyruvate carboxylase of the C 4 cycle was determined by exposing leaves to 14 CO 2 for 3 to 16 seconds, and extrapolating the labeling curves of initial products to zero time. Results indicated that ∼94% of the CO 2 was fixed by the C 4 cycle in high light grown plants, versus ∼78% in low light grown plants. Consistent with the carbon partitioning patterns, photosynthetic enzyme activities (on a chlorophyll basis) in protoplasts from leaves of high light grown plants showed a more C 4 -like pattern of compartmentation. Pyruvate,Pi dikinase and phosphoenolpyruvate carboxylase were more enriched in the mesophyll cells, while NADP-malic enzyme and ribulose 1,5-bisphosphate carboxylase/oxygenase were relatively more abundant in the bundle sheath cells of high light than of low light grown plants

Signification biogéographique des processus d'adaptation photosynthétiques : 1. L'exemple des Kalanchoe malgaches

OpenAIRE

Brulfert, J.; Ravelomanana, D.; Gehrig, H.; Kluge, M.

1996-01-01

Le Métabolisme Acide des Crassulacées (CAM) est un type de photosynthèse présenté par les plantes qui ont dans les conditions naturelles à faire face à une contrainte hydrique. Il est caractérisé par la capacité de fixer le CO2 externe pendant la nuit (via la phosphoenolpyruvate carboxylase, PEPC) mais aussi pendant le jour (via la ribulose bisphosphate carboxylase oxygénase, Rubisco). Ces propriétés sont associées à un comportement particulier des stomates qui sont ouverts la nuit (favorisan...

The moonlighting function of pyruvate carboxylase resides in the non-catalytic end of the TIM barrel.

NARCIS (Netherlands)

Huberts, D.H.; Venselaar, H.; Vriend, G.; Veenhuis, M.; Klei, I.J. van der

2010-01-01

Pyruvate carboxylase is a highly conserved enzyme that functions in replenishing the tricarboxylic acid cycle with oxaloacetate. In the yeast Hansenulapolymorpha, the pyruvate carboxylase protein is also required for import and assembly of the peroxisomal enzyme alcohol oxidase. This additional

The moonlighting function of pyruvate carboxylase resides in the non-catalytic end of the TIM barrel

NARCIS (Netherlands)

Huberts, Daphne H. E. W.; Venselaar, Hanka; Vriend, Gert; Veenhuis, Marten; van der Klei, Ida J.

Pyruvate carboxylase is a highly conserved enzyme that functions in replenishing the tricarboxylic acid cycle with oxaloacetate. In the yeast Hansenula polymorpha, the pyruvate carboxylase protein is also required for import and assembly of the peroxisomal enzyme alcohol oxidase. This additional

Genes encoding biotin carboxylase subunit of acetyl-CoA carboxylase from Brassica napus and parental species: cloning, expression patterns, and evolution

Science.gov (United States)

Comparative genomics is a useful tool to investigate gene and genome evolution. Biotin carboxylase (BC), an important subunit of heteromeric ACCase that is a rate-limiting enzyme in fatty acid biosynthesis in dicots, catalyzes ATP, biotin-carboxyl-carrier protein and CO2 to form carboxybiotin-carbo...

Stem juice production of the C4 sugarcane (Saccharum officinarum) is enhanced by growth at double-ambient CO2 and high temperature.

Science.gov (United States)

Vu, Joseph C V; Allen, Leon H

2009-07-15

Two cultivars of sugarcane (Saccharum officinarum cv. CP73-1547 and CP88-1508) were grown for 3 months in paired-companion, temperature-gradient, sunlit greenhouses under daytime [CO2] of 360 (ambient) and 720 (double ambient) micromol mol(-1) and at temperatures of 1.5 degrees C (near ambient) and 6.0 degrees C higher than outside ambient temperature. Leaf area and biomass, stem biomass and juice and CO2 exchange rate (CER) and activities of ribulose bisphosphate carboxylase-oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC) of fully developed leaves were measured at harvest. On a main stem basis, leaf area, leaf dry weight, stem dry weight and stem juice volume were increased by growth at doubled [CO2] or high temperature. Such increases were even greater under combination of doubled [CO2]/high temperature. Plants grown at doubled [CO2]/high temperature combination averaged 50%, 26%, 84% and 124% greater in leaf area, leaf dry weight, stem dry weight and stem juice volume, respectively, compared with plants grown at ambient [CO2]/near-ambient temperature combination. In addition, plants grown at doubled [CO2]/high temperature combination were 2-3-fold higher in stem soluble solids than those at ambient [CO2]/near-ambient temperature combination. Although midday CER of fully developed leaves was not affected by doubled [CO2] or high temperature, plants grown at doubled [CO2] were 41-43% less in leaf stomatal conductance and 69-79% greater in leaf water-use efficiency, compared with plants grown at ambient [CO2]. Activity of PEPC was down-regulated 23-32% at doubled [CO2], while high temperature did not have a significant impact on this enzyme. Activity of Rubisco was not affected by growth at doubled [CO2], but was reduced 15-28% at high temperature. The increases in stem juice production and stem juice soluble solids concentration for sugarcane grown at doubled [CO2] or high temperature, or at doubled [CO2]/high temperature combination, were partially

Activation of acetyl-coenzyme A carboxylase is involved in Taxol-induced ovarian cancer cell death.

Science.gov (United States)

Wu, Jiang; Ji, Fang; DI, Wen; Chen, Hongduo; Wan, Yinsheng

2011-05-01

Acetyl-coenzyme A carboxylase (ACC) is an attractive target for research into the treatment of a variety of human diseases, including diabetes, obesity and cancer. Mounting evidence suggests that the inhibition of ACC induced of cancer cell apoptosis. However, whether the inhibition of ACC regulates apoptosis in CaOV3 cancer cells has yet to be addressed. This study investigated the cytotoxic mechanism of action of ACC inhibition. Results showed that 5-(tetradecyloxy)-2-furoic acid (TOFA), an ACC inhibitor, enhanced Taxol-induced CaOV3 human ovarian cancer cell apoptosis. Notably, when TOFA was administered as a monotherapy, it induced CaOV3 cell apoptosis. Pre-treatment with the EGFR inhibitor PD153035 was found to markedly enhance ACC phosphorylation, whereas AMP-activated protein kinase (AMPK) activator AICAR was found to marginally enhance ACC phosphorylation. Taken together, the data showed ACC is a potential novel molecular target of Taxol. Additionally, ACC inhibition partially contributed to the cytotoxic effect of Taxol in ovarian cancer cells.

Escherichia coli Phosphoenolpyruvate Dependent Phosphotransferase System. Copurification of HPr and α1-6 Glucan

NARCIS (Netherlands)

Dooijewaard, G.; Roossien, F.F.; Robillard, G.T.

1979-01-01

A rapid, high-yield procedure has been developed for the purification of HPr from the Escherichia coli phosphoenolpyruvate dependent phosphotransferase system. During this procedure, the protein copurifies with a 2500-dalton homopolysaccharide which we have identified as α1-6 glucan. The results of

Amino acid environment determines expression of carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase in embryonic rat hepatocytes

NARCIS (Netherlands)

Lamers, W. H.; van Roon, M.; Mooren, P. G.; de Graaf, A.; Charles, R.

1985-01-01

A completely defined medium (EHM-1), which reflects the amino acid composition of fetal rat serum and contains albumin as the sole proteinaceous compound, allows the accumulation of carbamoylphosphate synthetase and phosphoenolpyruvate carboxykinase in the presence of dexamethasone, dibutyryl cyclic

Computational redesign of bacterial biotin carboxylase inhibitors using structure-based virtual screening of combinatorial libraries.

Science.gov (United States)

Brylinski, Michal; Waldrop, Grover L

2014-04-02

As the spread of antibiotic resistant bacteria steadily increases, there is an urgent need for new antibacterial agents. Because fatty acid synthesis is only used for membrane biogenesis in bacteria, the enzymes in this pathway are attractive targets for antibacterial agent development. Acetyl-CoA carboxylase catalyzes the committed and regulated step in fatty acid synthesis. In bacteria, the enzyme is composed of three distinct protein components: biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase. Fragment-based screening revealed that amino-oxazole inhibits biotin carboxylase activity and also exhibits antibacterial activity against Gram-negative organisms. In this report, we redesigned previously identified lead inhibitors to expand the spectrum of bacteria sensitive to the amino-oxazole derivatives by including Gram-positive species. Using 9,411 small organic building blocks, we constructed a diverse combinatorial library of 1.2×10⁸ amino-oxazole derivatives. A subset of 9×10⁶ of these compounds were subjected to structure-based virtual screening against seven biotin carboxylase isoforms using similarity-based docking by eSimDock. Potentially broad-spectrum antibiotic candidates were selected based on the consensus ranking by several scoring functions including non-linear statistical models implemented in eSimDock and traditional molecular mechanics force fields. The analysis of binding poses of the top-ranked compounds docked to biotin carboxylase isoforms suggests that: (1) binding of the amino-oxazole anchor is stabilized by a network of hydrogen bonds to residues 201, 202 and 204; (2) halogenated aromatic moieties attached to the amino-oxazole scaffold enhance interactions with a hydrophobic pocket formed by residues 157, 169, 171 and 203; and (3) larger substituents reach deeper into the binding pocket to form additional hydrogen bonds with the side chains of residues 209 and 233. These structural insights into drug

Mycobacterium tuberculosis Phosphoenolpyruvate Carboxykinase Is Regulated by Redox Mechanisms and Interaction with Thioredoxin

Czech Academy of Sciences Publication Activity Database

Machová, Iva; Snášel, Jan; Zimmermann, M.; Laubitz, D.; Plocinski, P.; Oehlmann, W.; Singh, M.; Dostál, Jiří; Sauer, U.; Pichová, Iva

2014-01-01

Roč. 289, č. 19 (2014), s. 13066-13078 ISSN 0021-9258 EU Projects: European Commission(XE) 241587 - SYSTEMTB Grant - others:OPPK(CZ) CZ.2.16/3.1.00/24016 Institutional support: RVO:61388963 Keywords : enzyme kinetics * hypoxia * metabolism * Mycobacterium tuberculosis * oxidation-reduction * thioredoxin * Phosphoenolpyruvate carboxykinase Subject RIV: CE - Biochemistry Impact factor: 4.573, year: 2014

The dynamic organization of fungal acetyl-CoA carboxylase

Science.gov (United States)

Hunkeler, Moritz; Stuttfeld, Edward; Hagmann, Anna; Imseng, Stefan; Maier, Timm

2016-04-01

Acetyl-CoA carboxylases (ACCs) catalyse the committed step in fatty-acid biosynthesis: the ATP-dependent carboxylation of acetyl-CoA to malonyl-CoA. They are important regulatory hubs for metabolic control and relevant drug targets for the treatment of the metabolic syndrome and cancer. Eukaryotic ACCs are single-chain multienzymes characterized by a large, non-catalytic central domain (CD), whose role in ACC regulation remains poorly characterized. Here we report the crystal structure of the yeast ACC CD, revealing a unique four-domain organization. A regulatory loop, which is phosphorylated at the key functional phosphorylation site of fungal ACC, wedges into a crevice between two domains of CD. Combining the yeast CD structure with intermediate and low-resolution data of larger fragments up to intact ACCs provides a comprehensive characterization of the dynamic fungal ACC architecture. In contrast to related carboxylases, large-scale conformational changes are required for substrate turnover, and are mediated by the CD under phosphorylation control.

Phosphoenolpyruvate carboxykinase and gluconeogenesis in grape pericarp.

Science.gov (United States)

Walker, Robert P; Battistelli, Alberto; Moscatello, Stefano; Técsi, László; Leegood, Richard C; Famiani, Franco

2015-12-01

Glycolysis from sugars is necessary at all stages of development of grape pericarp, and this raises the question as to why gluconeogenesis from malate occurs. Phosphoenolpyruvate carboxykinase (PEPCK) is required for gluconeogenesis in grape pericarp. In this study we determined the abundance of PEPCK protein and activity in different parts of grape pericarp during its development. Both PEPCK protein and activity were present throughout development, however, in both the skin and the flesh their abundance increased greatly at the start of ripening. This coincided with the onset of the decrease in the malate content of the berry. The location of PEPCK in the pericarp at different stages of development was determined using both immunohistochemistry and dissection. We provide a possible explanation for the occurrence of gluconeogenesis in grape pericarp. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Brain-derived neurotrophic factor is produced by skeletal muscle cells in response to contraction and enhances fat oxidation via activation of AMP-activated protein kinase

DEFF Research Database (Denmark)

Matthews, V B; Åström, Maj-Brit; Chan, M H S

2009-01-01

C12 skeletal muscle cells were electrically stimulated to mimic contraction. L6 myotubes and isolated rat extensor digitorum longus muscles were treated with BDNF and phosphorylation of the proteins AMP-activated protein kinase (AMPK) (Thr(172)) and acetyl coenzyme A carboxylase beta (ACCbeta) (Ser...... kinase (p44/42 Thr(202)/Tyr(204)) phosphorylation in these muscles. In addition, phosphorylation of ACCbeta was markedly elevated in the Bdnf electroporated muscles. CONCLUSIONS/INTERPRETATION: These data identify BDNF as a contraction-inducible protein in skeletal muscle that is capable of enhancing...

Occurrence of a number of enzymes involved in either gluconeogenesis or other processes in the pericarp of three cultivars of grape (Vitis vinifera L.) during development.

Science.gov (United States)

Famiani, Franco; Moscatello, Stefano; Ferradini, Nicoletta; Gardi, Tiziano; Battistelli, Alberto; Walker, Robert P

2014-11-01

It is uncertain whether the enzymes pyruvate orthophosphate dikinase (PPDK) or isocitrate lyase (ICL) are present in the pericarp of grape, in which they could function in gluconeogenesis. The occurrence of these and other enzymes was investigated in the pericarp of three cultivars of grape (Vitis vinifera L.). In particular, the abundance of the enzymes aldolase, glutamine synthase (GS), acid invertase, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPC), PPDK and ICL were determined during the development of the pericarp of the cultivars Cabernet Sauvignon, Chardonnay and Zibibbo. PPDK and ICL were not detected at any stage of development. Each of the other enzymes showed different changes in abundance during development. However, for a given enzyme its changes in abundance were similar in each cultivar. In the ripe pericarp of Cabernet Sauvignon, PEPC, cytosolic GS and aldolase were equally distributed between the vasculature and parenchyma cells of the flesh and skin. The absence or very low abundance of PPDK provides strong evidence that any gluconeogenesis from malate utilises phosphoenolpyruvate carboxykinase (PEPCK). The absence or very low abundance of ICL in the pericarp precludes any gluconeogenesis from ethanol. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Photosynthesis-related characteristics of the midrib and the interveinal lamina in leaves of the C3-CAM intermediate plant Mesembryanthemum crystallinum.

Science.gov (United States)

Kuźniak, Elżbieta; Kornas, Andrzej; Kaźmierczak, Andrzej; Rozpądek, Piotr; Nosek, Michał; Kocurek, Maciej; Zellnig, Günther; Müller, Maria; Miszalski, Zbigniew

2016-06-01

Leaf veins are usually encircled by specialized bundle sheath cells. In C4 plants, they play an important role in CO2 assimilation, and the photosynthetic activity is compartmentalized between the mesophyll and the bundle sheath. In C3 and CAM (Crassulacean acid metabolism) plants, the photosynthetic activity is generally attributed to the leaf mesophyll cells, and the vascular parenchymal cells are rarely considered for their role in photosynthesis. Recent studies demonstrate that enzymes required for C4 photosynthesis are also active in the veins of C3 plants, and their vascular system contains photosynthetically competent parenchyma cells. However, our understanding of photosynthesis in veins of C3 and CAM plants still remains insufficient. Here spatial analysis of photosynthesis-related properties were applied to the midrib and the interveinal lamina cells in leaves of Mesembryanthemum crystallinum, a C3-CAM intermediate plant. The midrib anatomy as well as chloroplast structure and chlorophyll fluorescence, diurnal gas exchange profiles, the immunoblot patterns of PEPC (phosphoenolpyruvate carboxylase) and RubisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), H2O2 localization and antioxidant enzyme activities were compared in the midrib and in the interveinal mesophyll cells in leaves of C3 and CAM plants. Leaf midribs were structurally competent to perform photosynthesis in C3 and CAM plants. The midrib chloroplasts resembled those in the bundle sheath cells of C4 plants and were characterized by limited photosynthetic activity. The metabolic roles of midrib chloroplasts differ in C3 and CAM plants. It is suggested that in leaves of C3 plants the midrib chloroplasts could be involved in the supply of CO2 for carboxylation, and in CAM plants they could provide malate to different metabolic processes and mediate H2O2 signalling. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For

Contribution of carbon fixed by Rubisco and PEPC to phloem export in the Crassulacean acid metabolism plant Kalanchoe daigremontiana.

Science.gov (United States)

Wild, Birgit; Wanek, Wolfgang; Postl, Wolfgang; Richter, Andreas

2010-03-01

Crassulacean acid metabolism (CAM) plants exhibit a complex interplay between CO(2) fixation by phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase oxygenase (Rubisco), and carbon demand for CAM maintenance and growth. This study investigated the flux of carbon from PEPC and direct Rubisco fixation to different leaf carbon pools and to phloem sap over the diurnal cycle. Concentrations and carbon isotope compositions of starch, soluble sugars, and organic acids were determined in leaves and phloem exudates of Kalanchoë daigremontiana Hamet et Perr., and related to CO(2) fixation by PEPC and Rubisco. Three types of leaf carbon pools could be distinguished. (i) Starch and malate pools were dominant and showed a pattern of reciprocal mobilization and accumulation (85/54 and 13/48 mg C g(-1) DW, respective, at the beginning/end of phase I). The carbon isotope composition of these pools was compatible with predominant PEPC fixation (delta(13)C values of -13 and -11 per thousand for starch and malate compared to -11 per thousand of PEPC fixed carbon). (ii) Isotopic composition (-17 per thousand and -14 per thousand) and concentration of glucose and fructose (2 and 3 mg C g(-1) DW, respectively) were not affected by diurnal metabolism, suggesting a low turnover. (iii) Sucrose (1-3 mg C g(-1) DW), in contrast, exhibited large diurnal changes in delta(13)C values (from -17 per thousand in the evening to -12 per thousand in the morning), which were not matched by net changes in sucrose concentration. This suggests a high sucrose turnover, fed by nocturnal starch degradation and direct Rubisco fixation during the day. A detailed dissection of the carbon fixation and mobilization pattern in K. daigremontiana revealed that direct fixation of Rubisco during the light accounted for 30% of phloem sucrose, but only 15% of fixed carbon, indicating that carbon from direct Rubisco fixation was preferentially used for leaf export.

Studies on enzymes of C-4 pathway : Part V - Comparative studies of RUP2 carboxylase/oxygenase from maize and spinach

International Nuclear Information System (INIS)

Ramakrishna, J.; Bhagwat, A.S.; Sane, P.V.

1978-01-01

RuP 2 carboxylase (EC 4.1.1.39) isolated from maize, a C-4 plant possessed oxygenase activity. The ratio of carboxylase/oxygenase in the case of maize enzyme was more than 2-fold as compared to that of spinach. Fructose-1 6-diphosphate preferentially inhibited oxygenase function of the RuP 2 carboxylase/oxygenase in both the species when both the activities were assayed under identical conditions of pH, temperature, MgCl 2 , O 2 and RuP 2 concentration. Frutose-1, 6-diphosphate showed a fully competitive inhibition with respect to RuP 2 in the case of spinach, however the maize enzyme was inhibited seminoncompetitively. ( 14 C)-HCO 3 was used in the carboxylase assay. (author)

Vitamin K-dependent carboxylase: Minimized escape of CO2 from solution may prolong linearity of the reaction rate

International Nuclear Information System (INIS)

Soute, B.A.; Bude, R.; Buitenhuis, H.; Vermeer, C.

1989-01-01

Escape of 14 CO 2 from the reaction mixture into the gas phase may seriously affect the accuracy of in vitro measurement of vitamin K-dependent carboxylase activity (and probably that of other carboxylases as well). In this paper we describe the effect of (a) the volume of the test tubes in which the reaction is performed, (b) the addition of an excess of NaH 12 CO 3 in parallel with standard amounts of NaH 14 CO 3 , and (c) the incubation temperature. In this way optimal conditions are defined and used for the carboxylation of various peptide and protein substrates. It is shown that both a prosequence and an internal recognition site contribute to the effective recognition of a substrate by carboxylase. The maximal efficiency of carboxylation was 1-2% with substrates lacking both signals and 20-50% if only one was present. This indicates the need for developing peptide substrates containing both recognition signals for vitamin K-dependent carboxylase

Biochemical signatures mimicking multiple carboxylase deficiency in children with mutations in MT-ATP6.

Science.gov (United States)

Larson, Austin A; Balasubramaniam, Shanti; Christodoulou, John; Burrage, Lindsay C; Marom, Ronit; Graham, Brett H; Diaz, George A; Glamuzina, Emma; Hauser, Natalie; Heese, Bryce; Horvath, Gabriella; Mattman, Andre; van Karnebeek, Clara; Lane Rutledge, S; Williamson, Amy; Estrella, Lissette; Van Hove, Johan K L; Weisfeld-Adams, James D

2018-01-04

Elevations of specific acylcarnitines in blood reflect carboxylase deficiencies, and have utility in newborn screening for life-threatening organic acidemias and other inherited metabolic diseases. In this report, we describe a newly-identified association of biochemical features of multiple carboxylase deficiency in individuals harboring mitochondrial DNA (mtDNA) mutations in MT-ATP6 and in whom organic acidemias and multiple carboxylase deficiencies were excluded. Using retrospective chart review, we identified eleven individuals with abnormally elevated propionylcarnitine (C3) or hydroxyisovalerylcarnitine (C5OH) with mutations in MT-ATP6, most commonly m.8993T>G in high heteroplasmy or homoplasmy. Most patients were ascertained on newborn screening; most had normal enzymatic or molecular genetic testing to exclude biotinidase and holocarboxylase synthetase deficiencies. MT-ATP6 is associated with some cases of Leigh disease; clinical outcomes in our cohort ranged from death from neurodegenerative disease in early childhood to clinically and developmentally normal after several years of follow-up. These cases expand the biochemical phenotype associated with MT-ATP6 mutations, especially m.8993T>G, to include acylcarnitine abnormalities mimicking carboxylase deficiency states. Clinicians should be aware of this association and its implications for newborn screening, and consider mtDNA sequencing in patients exhibiting similar acylcarnitine abnormalities that are biotin-unresponsive and in whom other enzymatic deficiencies have been excluded. Copyright © 2018 Elsevier B.V. and Mitochondria Research Society. All rights reserved.

FGF21 does not require adipocyte AMP-activated protein kinase (AMPK) or the phosphorylation of acetyl-CoA carboxylase (ACC) to mediate improvements in whole-body glucose homeostasis

DEFF Research Database (Denmark)

Mottillo, Emilio P; Desjardins, Eric M; Fritzen, Andreas Mæchel

2017-01-01

1β2AKO) and littermate controls were fed a high fat diet (HFD) and treated with native FGF21 or saline for two weeks. Additionally, HFD-fed mice with knock-in mutations on the AMPK phosphorylation sites of acetyl-CoA carboxylase (ACC)1 and ACC2 (DKI mice) along with wild-type (WT) controls received...

Ixodes scapularis Tick Cells Control Anaplasma phagocytophilum Infection by Increasing the Synthesis of Phosphoenolpyruvate from Tyrosine

Czech Academy of Sciences Publication Activity Database

Cabezas Cruz, Alejandro; Espinosa, P. J.; Obregon, D. A.; Alberdi, P.; de la Fuente, J.

2017-01-01

Roč. 7, AUG 17 (2017), č. článku 375. ISSN 2235-2988 Institutional support: RVO:60077344 Keywords : proteomics * transcriptomics * phosphoenolpyruvate * glycerol-3-phosphate * Ixodes scapularis * Anaplasma phagocytophilum Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.300, year: 2016

InterProScan Result: FS885591 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS885591 FS885591_3_ORF2 718F710ADBEB9510 SUPERFAMILY SSF51621 Phosphoenolpyruvate/pyruva...te domain 1.3e-13 T IPR015813 Pyruvate/Phosphoenolpyruvate kinase, catalytic core Molecular Function: catalytic activity (GO:0003824) ...

InterProScan Result: FS880233 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS880233 FS880233_1_ORF2 88C10776BC024404 SUPERFAMILY SSF51621 Phosphoenolpyruvate/pyruva...te domain 1.9e-07 T IPR015813 Pyruvate/Phosphoenolpyruvate kinase, catalytic core Molecular Function: catalytic activity (GO:0003824) ...

Properties of ribulose diphosphate carboxylase immobilized on porous glass

Science.gov (United States)

Shapira, J.; Hanson, C. L.; Lyding, J. M.; Reilly, P. J.

1974-01-01

Ribulose-1,5-diphosphate carboxylase from spinach has been bound to arylamine porous glass with a diazo linkage and to alklamine porous glass with glutaraldehyde. Stability at elevated temperatures and responses to changes of pH and ribulose-1,5-diphosphate, Mg(2+), and dithiothreitol concentrations were not significantly different from the soluble enzyme, though stability at 4 C was somewhat improved.

Arctigenin protects against steatosis in WRL68 hepatocytes through activation of phosphoinositide 3-kinase/protein kinase B and AMP-activated protein kinase pathways.

Science.gov (United States)

Chen, Kung-Yen; Lin, Jui-An; Yao, Han-Yun; Hsu, An-Chih; Tai, Yu-Ting; Chen, Jui-Tai; Hsieh, Mao-Chih; Shen, Tang-Long; Hsu, Ren-Yi; Wu, Hong-Tan; Wang, Guey Horng; Ho, Bing-Ying; Chen, Yu-Pei

2018-04-01

Arctigenin (ATG), a lignin extracted from Arctium lappa (L.), exerts antioxidant and anti-inflammatory effects. We hypothesized that ATG exerts a protective effect on hepatocytes by preventing nonalcoholic fatty liver disease (NAFLD) progression associated with lipid oxidation-associated lipotoxicity and inflammation. We established an in vitro NAFLD cell model by using normal WRL68 hepatocytes to investigate oleic acid (OA) accumulation and the potential bioactive role of ATG. The results revealed that ATG inhibited OA-induced lipid accumulation, lipid peroxidation, and inflammation in WRL68 hepatocytes, as determined using Oil Red O staining, thiobarbituric acid reactive substance assay, and inflammation antibody array assays. Quantitative RT-PCR analysis demonstrated that ATG significantly mitigated the expression of acetylcoenzyme A carboxylase 1 and sterol regulatory element-binding protein-1 and significantly increased the expression of carnitine palmitoyltransferase 1 and peroxisome proliferator-activated receptor alpha. The 40 targets of the Human Inflammation Antibody Array indicated that ATG significantly inhibited the elevation of the U937 lymphocyte chemoattractant, ICAM-1, IL-1β, IL-6, IL-6sR, IL-7, and IL-8. ATG could activate the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) and AMP-activated protein kinase (AMPK) pathways and could increase the phosphorylation levels of Akt and AMPK to mediate cell survival, lipid metabolism, oxidation stress, and inflammation. Thus, we demonstrated that ATG could inhibit NAFLD progression associated with lipid oxidation-associated lipotoxicity and inflammation, and we provided insights into the underlying mechanisms and revealed potential targets to enable a thorough understanding of NAFLD progression. Copyright © 2018 Elsevier Inc. All rights reserved.

Insect acetyl-CoA carboxylase: activity during the larval, pupal and adult stages of insect development.

Science.gov (United States)

Goldring, J P; Read, J S

1993-12-01

1. The activity of the lipogenic enzyme, acetyl-CoA carboxylase, was investigated in four insect species; Bombyx mori (Lepidoptera), Tenebrio molitor (Coleoptera), Glossina morsitans and Sarcophaga nodosa (Diptera). 2. Acetyl-CoA carboxylase activity in larval, pupal and adult forms was compared with the saponifiable lipid mass at each stage of the life-cycle, and found to follow similar patterns except for Tenebrio molitor. 3. The results are examined in relation to known metabolic requirements for each insect.

InterProScan Result: FS895314 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS895314 FS895314_5_ORF1 97DB8176F1361E8C SUPERFAMILY SSF51621 Phosphoenolpyruvate/pyruva...te domain 1e-21 T IPR015813 Pyruvate/Phosphoenolpyruvate kinase, catalytic core Molecular Function: catalytic activity (GO:0003824) ...

InterProScan Result: BW998452 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available BW998452 BW998452_1_ORF1 60C99737A60E9D72 SUPERFAMILY SSF51621 Phosphoenolpyruvate/pyruva...te domain 7.1e-22 T IPR015813 Pyruvate/Phosphoenolpyruvate kinase, catalytic core Molecular Function: catalytic activity (GO:0003824) ...

InterProScan Result: FS869255 [KAIKOcDNA[Archive

Lifescience Database Archive (English)

Full Text Available FS869255 FS869255_4_ORF1 7290E0DA14F8EDE2 SUPERFAMILY SSF51621 Phosphoenolpyruvate/pyruva...te domain 1.1e-55 T IPR015813 Pyruvate/Phosphoenolpyruvate kinase, catalytic core Molecular Function: catalytic activity (GO:0003824) ...

Acetone and Butanone Metabolism of the Denitrifying Bacterium “Aromatoleum aromaticum” Demonstrates Novel Biochemical Properties of an ATP-Dependent Aliphatic Ketone Carboxylase

Science.gov (United States)

Schühle, Karola

2012-01-01

The anaerobic and aerobic metabolism of acetone and butanone in the betaproteobacterium “Aromatoleum aromaticum” is initiated by their ATP-dependent carboxylation to acetoacetate and 3-oxopentanoic acid, respectively. Both reactions are catalyzed by the same enzyme, acetone carboxylase, which was purified and characterized. Acetone carboxylase is highly induced under growth on acetone or butanone and accounts for at least 5.5% of total cell protein. The enzyme consists of three subunits of 85, 75, and 20 kDa, respectively, in a (αβγ)2 composition and contains 1 Zn and 2 Fe per heterohexamer but no organic cofactors. Chromatographic analysis of the ATP hydrolysis products indicated that ATP was exclusively cleaved to AMP and 2 Pi. The stoichiometry was determined to be 2 ATP consumed per acetone carboxylated. Purified acetone carboxylase from A. aromaticum catalyzes the carboxylation of acetone and butanone as the only substrates. However, the enzyme shows induced (uncoupled) ATPase activity with many other substrates that were not carboxylated. Acetone carboxylase is a member of a protein family that also contains acetone carboxylases of various other organisms, acetophenone carboxylase of A. aromaticum, and ATP-dependent hydantoinases/oxoprolinases. While the members of this family share several characteristic features, they differ with respect to the products of ATP hydrolysis, subunit composition, and metal content. PMID:22020645

A plant/fungal-type phosphoenolpyruvate carboxykinase located in the parasite mitochondrion ensures glucose-independent survival of Toxoplasma gondii.

Science.gov (United States)

Nitzsche, Richard; Günay-Esiyok, Özlem; Tischer, Maximilian; Zagoriy, Vyacheslav; Gupta, Nishith

2017-09-15

Toxoplasma gondii is considered to be one of the most successful intracellular pathogens, because it can reproduce in varied nutritional milieus, encountered in diverse host cell types of essentially any warm-blooded organism. Our earlier work demonstrated that the acute (tachyzoite) stage of T. gondii depends on cooperativity of glucose and glutamine catabolism to meet biosynthetic demands. Either of these two nutrients can sustain the parasite survival; however, what determines the metabolic plasticity has not yet been resolved. Here, we reveal two discrete phosphoenolpyruvate carboxykinase (PEPCK) enzymes in the parasite, one of which resides in the m i t ochondrion ( Tg PEPCK mt ), whereas the other protein is n ot e xpressed in t achyzoites ( Tg PEPCK net ). Parasites with an intact glycolysis can tolerate genetic deletions of Tg PEPCK mt as well as of Tg PEPCK net , indicating their nonessential roles for tachyzoite survival. Tg PEPCK net can also be ablated in a glycolysis-deficient mutant, while Tg PEPCK mt is refractory to deletion. Consistent with this, the lytic cycle of a conditional mutant of Tg PEPCK mt in the glycolysis-impaired strain was aborted upon induced repression of the mitochondrial isoform, demonstrating its essential role for the glucose-independent survival of parasites. Isotope-resolved metabolomics of the conditional mutant revealed defective flux of glutamine-derived carbon into RNA-bound ribose sugar as well as metabolites associated with gluconeogenesis, entailing a critical nodal role of PEPCK mt in linking catabolism of glucose and glutamine with anabolic pathways. Our data also suggest a homeostatic function of Tg PEPCK mt in cohesive operation of glycolysis and the tricarboxylic acid cycle in a normal glucose-replete milieu. Conversely, we found that the otherwise integrative enzyme pyruvate carboxylase ( Tg PyC) is dispensable not only in glycolysis-competent but also in glycolysis-deficient tachyzoites despite a mitochondrial

Crystal structure of the 500-kDa yeast acetyl-CoA carboxylase holoenzyme dimer

Energy Technology Data Exchange (ETDEWEB)

Wei, Jia; Tong, Liang

2015-10-12

Acetyl-CoA carboxylase (ACC) has crucial roles in fatty acid metabolism and is an attractive target for drug discovery against diabetes, cancer and other diseases1, 2, 3, 4, 5, 6. Saccharomyces cerevisiae ACC (ScACC) is crucial for the production of very-long-chain fatty acids and the maintenance of the nuclear envelope7, 8. ACC contains biotin carboxylase (BC) and carboxyltransferase (CT) activities, and its biotin is linked covalently to the biotin carboxyl carrier protein (BCCP). Most eukaryotic ACCs are 250-kilodalton (kDa), multi-domain enzymes and function as homodimers and higher oligomers. They contain a unique, 80-kDa central region that shares no homology with other proteins. Although the structures of the BC, CT and BCCP domains and other biotin-dependent carboxylase holoenzymes are known1, 9, 10, 11, 12, 13, 14, there is currently no structural information on the ACC holoenzyme. Here we report the crystal structure of the full-length, 500-kDa holoenzyme dimer of ScACC. The structure is remarkably different from that of the other biotin-dependent carboxylases. The central region contains five domains and is important for positioning the BC and CT domains for catalysis. The structure unexpectedly reveals a dimer of the BC domain and extensive conformational differences compared to the structure of the BC domain alone, which is a monomer. These structural changes reveal why the BC domain alone is catalytically inactive and define the molecular mechanism for the inhibition of eukaryotic ACC by the natural product soraphen A15, 16 and by phosphorylation of a Ser residue just before the BC domain core in mammalian ACC. The BC and CT active sites are separated by 80 Å, and the entire BCCP domain must translocate during catalysis.

Overexpression of ubiquitous 6-phosphofructo-2-kinase in the liver of transgenic mice results in weight gain

International Nuclear Information System (INIS)

Duran, Joan; Navarro-Sabate, Aurea; Pujol, Anna; Perales, Jose C.; Manzano, Anna; Obach, Merce; Gomez, Marta; Bartrons, Ramon

2008-01-01

Fructose 2,6-bisphosphate (Fru-2,6-P 2 ) is an important metabolite that controls glycolytic and gluconeogenic pathways in several cell types. Its synthesis and degradation are catalyzed by the bifunctional enzyme 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase (PFK-2). Four genes, designated Pfkfb1-4, codify the different PFK-2 isozymes. The Pfkfb3 gene product, ubiquitous PFK-2 (uPFK-2), has the highest kinase/bisphosphatase activity ratio and is associated with proliferation and tumor metabolism. A transgenic mouse model that overexpresses uPFK-2 under the control of the phosphoenolpyruvate carboxykinase promoter was designed to promote sustained and elevated Fru-2,6-P 2 levels in the liver. Our results demonstrate that in diet-induced obesity, high Fru-2,6-P 2 levels in transgenic livers caused changes in hepatic gene expression profiles for key gluconeogenic and lipogenic enzymes, as well as an accumulation of lipids in periportal cells, and weight gain

The AMP-activated protein kinase is involved in the regulation of ketone body production by astrocytes.

Science.gov (United States)

Blázquez, C; Woods, A; de Ceballos, M L; Carling, D; Guzmán, M

1999-10-01

The possible role of the AMP-activated protein kinase (AMPK), a highly conserved stress-activated kinase, in the regulation of ketone body production by astrocytes was studied. AMPK activity in rat cortical astrocytes was three times higher than in rat cortical neurons. AMPK in astrocytes was shown to be functionally active. Thus, incubation of astrocytes with 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a cell-permeable activator of AMPK, stimulated both ketogenesis from palmitate and carnitine palmitoyltransferase I. This was concomitant to a decrease of intracellular malonyl-CoA levels and an inhibition of acetyl-CoA carboxylase/fatty acid synthesis and 3-hydroxy-3-methylglutaryl-CoA reductase/cholesterol synthesis. Moreover, in microdialysis experiments AICAR was shown to stimulate brain ketogenesis markedly. The effect of chemical hypoxia on AMPK and the ketogenic pathway was studied subsequently. Incubation of astrocytes with azide led to a remarkable drop of fatty acid beta-oxidation. However, activation of AMPK during hypoxia compensated the depression of beta-oxidation, thereby sustaining ketone body production. This effect seemed to rely on the cascade hypoxia --> increase of the AMP/ATP ratio --> AMPK stimulation --> acetyl-CoA carboxylase inhibition --> decrease of malonyl-CoA concentration --> carnitine palmitoyltransferase I deinhibition --> enhanced ketogenesis. Furthermore, incubation of neurons with azide blunted lactate oxidation, but not 3-hydroxybutyrate oxidation. Results show that (a) AMPK plays an active role in the regulation of ketone body production by astrocytes, and (b) ketone bodies produced by astrocytes during hypoxia might be a substrate for neuronal oxidative metabolism.

Redundancy of stomatal control for the circadian photosynthetic rhythm in Kalanchoë daigremontiana Hamet et Perrier.

Science.gov (United States)

Wyka, T P; Duarte, H M; Lüttge, U E

2005-03-01

In continuous light, the Crassulacean acid metabolism plant Kalanchoe daigremontiana Hamet et Perrier has a circadian rhythm of gas exchange with peaks occurring during the subjective night. The rhythm of gas exchange is coupled to a weak, reverse phased rhythm of quantum yield of photosystem II (Phi (PSII)). To test if the rhythm of Phi (PSII) persists in the absence of stomatal control, leaves were coated with a thin layer of translucent silicone grease which prevented CO2 and H2O exchange. In spite of this treatment, the rhythm of Phi (PSII) occurred with close to normal phase timing and with a much larger amplitude than in uncoated leaves. The mechanism underlying the Phi (PSII) rhythm in coated leaves can be explained by a circadian activity of phosphoenolpyruvate carboxylase (PEPC). At peaks of PEPC activity, the small amount of CO2 contained in the coated leaf could have become depleted, preventing the carboxylase activity of Rubisco and causing decreases in electron transport rates (observed as deep troughs of Phi (PSII) at 23-h in LL and at ca. 24-h intervals afterwards). Peaks of Phi (PSII) would be caused by a downregulation of PEPC leading to improved supply of CO2 to Rubisco. Substrate limitation of photochemistry at 23 h (trough of Phi (PSII)) was also suggested by the weak response of ETR in coated leaves to stepwise light enhancement. These results show that photosynthetic rhythmicity in K. daigremontiana is independent of stomatal regulation and may originate in the mesophyll.

Regulation of Ribulose-1,5-Bisphosphate Carboxylase Activity by the Activase System in Lysed Spinach Chloroplasts

Science.gov (United States)

Parry, Martin A. J.; Keys, Alfred J.; Foyer, Christine H.; Furbank, Robert T.; Walker, David A.

1988-01-01

Ribulose-1,5-bisphosphate (RuBP) carboxylase in lysed spinach (Spinacia oleracea L. cv virtuosa) chloroplasts that had been partly inactivated at low CO2 and Mg2+ by incubating in darkness with 4 millimolar partially purified RuBP was reactivated by light. If purified RuBP was used to inhibit dark activation of the enzyme, reactivation by light was not observed unless fructose-1,6-bisphosphate, ATP, or ADP plus inorganic phosphate were also added. Presumably, ADP plus inorganic phosphate acted as an ATP-generating system with a requirement for the generation of ΔpH across the thylakoid membrane. When the RuBP obtained from Sigma Chemical Co. was used, light did not reactivate the enzyme. There was no direct correlation between ΔpH and activation. Therefore, thylakoids are required in the ribulose-1,5-bisphosphate carboxylase activase system largely to synthesize ATP. Inactivation of RuBP carboxylase in isolated chloroplasts or in the lysed chloroplast system was not promoted simply by a transition from light to dark conditions but was caused by low CO2 and Mg2+. PMID:16666184

CZK3, a MAP kinase kinase kinase homolog in Cercospora zeae-maydis, regulates cercosporin biosynthesis, fungal development, and pathogenesis.

Science.gov (United States)

Shim, Won-Bo; Dunkle, Larry D

2003-09-01

The fungus Cercospora zeae-maydis causes gray leaf spot of maize and produces cercosporin, a photosensitizing perylenequinone with toxic activity against a broad spectrum of organisms. However, little is known about the biosynthetic pathway or factors that regulate cercosporin production. Analysis of a cDNA subtraction library comprised of genes that are up-regulated during cercosporin synthesis revealed a sequence highly similar to mitogen-activated protein (MAP) kinases in other fungi. Sequencing and conceptual translation of the full-length genomic sequence indicated that the gene, which we designated CZK3, contains a 4,119-bp open reading frame devoid of introns and encodes a 1,373-amino acid sequence that is highly similar to Wis4, a MAP kinase kinase kinase in Schizosaccharomyces pombe. Targeted disruption of CZK3 suppressed expression of genes predicted to participate in cercosporin biosynthesis and abolished cercosporin production. The disrupted mutants grew faster on agar media than the wild type but were deficient in conidiation and elicited only small chlorotic spots on inoculated maize leaves compared with rectangular necrotic lesions incited by the wild type. Complementation of disruptants with the CZK3 open reading frame and flanking sequences restored wild-type levels of conidiation, growth rate, and virulence as well as the ability to produce cercosporin. The results suggest that cercosporin is a virulence factor in C. zeae-maydis during maize pathogenesis, but the pleiotropic effects of CZK3 disruption precluded definitive conclusions.

Biosynthesis of sucrose and mannitol as a function of leaf age in celery (Apium graveolens L. )

Energy Technology Data Exchange (ETDEWEB)

Davis, J.M.; Fellman, J.K.; Loescher, W.H.

1988-01-01

In celery (Apium graveolens L.), the two major translocated carbohydrates are sucrose and the acyclic polyol mannitol. Their metabolism, however, is different and their specific functions are uncertain. To compare their roles in carbon partitioning and sink-source transitions, developmental changes in /sup 14/CO/sub 2/ labeling, pool sizes, and key enzyme activities in leaf tissues were examined. The proportion of label in mannitol increased dramatically with leaf maturation whereas that in sucrose remained fairly constant. Mannitol content, however, was high in all leaves and sucrose content increased as leaves developed. Activities of mannose-6-P reductase, cytoplasmic and chloroplastic fructose-1,6-bis-phosphatases, sucrose phosphate synthase, and sucrose synthase increased with leaf maturation and decreased as leaves senesced. Ribulose bisphosphate carboxylase and nonreversible glyceraldehyde-3-P dehydrogenase activities rose as leaves developed but did not decrease. Thus, sucrose is produced in all photosynthetically active leaves whereas mannitol is synthesized primarily in mature leaves and stored in all leaves. Onset of sucrose export in celery may result from sucrose accumulation in expanding leaves, but mannitol export is clearly unrelated to mannitol concentration. Mannitol export, however, appears to coincide with increased mannitol biosynthesis. Although mannitol and sucrose arise from a common precursor in celery, subsequent metabolism and transport must be regulated separately.

Screening Phosphorylation Site Mutations in Yeast Acetyl-CoA Carboxylase Using Malonyl-CoA Sensor to Improve Malonyl-CoA-Derived Product.

Science.gov (United States)

Chen, Xiaoxu; Yang, Xiaoyu; Shen, Yu; Hou, Jin; Bao, Xiaoming

2018-01-01

Malonyl-coenzyme A (malonyl-CoA) is a critical precursor for the biosynthesis of a variety of biochemicals. It is synthesized by the catalysis of acetyl-CoA carboxylase (Acc1p), which was demonstrated to be deactivated by the phosphorylation of Snf1 protein kinase in yeast. In this study, we designed a synthetic malonyl-CoA biosensor and used it to screen phosphorylation site mutations of Acc1p in Saccharomyces cerevisiae . Thirteen phosphorylation sites were mutated, and a combination of three site mutations in Acc1p, S686A, S659A, and S1157A, was found to increase malonyl-CoA availability. ACC1 S686AS659AS1157A expression also improved the production of 3-hydroxypropionic acid, a malonyl-CoA-derived chemical, compared to both wild type and the previously reported ACC1 S659AS1157A mutation. This mutation will also be beneficial for other malonyl-CoA-derived products.

Cysteine proteinases regulate chloroplast protein content and composition in tobacco leaves: a model for dynamic interactions with ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) vesicular bodies.

Science.gov (United States)

Prins, Anneke; van Heerden, Philippus D R; Olmos, Enrique; Kunert, Karl J; Foyer, Christine H

2008-01-01

The roles of cysteine proteinases (CP) in leaf protein accumulation and composition were investigated in transgenic tobacco (Nicotiana tabacum L.) plants expressing the rice cystatin, OC-1. The OC-1 protein was present in the cytosol, chloroplasts, and vacuole of the leaves of OC-1 expressing (OCE) plants. Changes in leaf protein composition and turnover caused by OC-1-dependent inhibition of CP activity were assessed in 8-week-old plants using proteomic analysis. Seven hundred and sixty-five soluble proteins were detected in the controls compared to 860 proteins in the OCE leaves. A cyclophilin, a histone, a peptidyl-prolyl cis-trans isomerase, and two ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase isoforms were markedly altered in abundance in the OCE leaves. The senescence-related decline in photosynthesis and Rubisco activity was delayed in the OCE leaves. Similarly, OCE leaves maintained higher leaf Rubisco activities and protein than controls following dark chilling. Immunogold labelling studies with specific antibodies showed that Rubisco was present in Rubisco vesicular bodies (RVB) as well as in the chloroplasts of leaves from 8-week-old control and OCE plants. Western blot analysis of plants at 14 weeks after both genotypes had flowered revealed large increases in the amount of Rubisco protein in the OCE leaves compared to controls. These results demonstrate that CPs are involved in Rubisco turnover in leaves under optimal and stress conditions and that extra-plastidic RVB bodies are present even in young source leaves. Furthermore, these data form the basis for a new model of Rubisco protein turnover involving CPs and RVBs.

Plasticity of crassulacean acid metabolism at subtropical latitudes: a pineapple case study.

Science.gov (United States)

Rainha, Nuno; Medeiros, Violante P; Câmara, Mariana; Faustino, Hélder; Leite, João P; Barreto, Maria do Carmo; Cruz, Cristina; Pacheco, Carlos A; Ponte, Duarte; Bernardes da Silva, Anabela

2016-01-01

Plants with the crassulacean acid metabolism (CAM) express high-metabolic plasticity, to adjust to environmental stresses. This article hypothesizes that irradiance and nocturnal temperatures are the major limitations for CAM at higher latitudes such as the Azores (37°45'N). Circadian CAM expression in Ananas comosus L. Merr. (pineapple) was assessed by the diurnal pattern of leaf carbon fixation into l-malate at the solstices and equinoxes, and confirmed by determining maximal phosphoenolpyruvate carboxylase (PEPC) activity in plant material. Metabolic adjustments to environmental conditions were confirmed by gas exchange measurements, and integrated with environmental data to determine CAM's limiting factors: light and temperature. CAM plasticity was observed at the equinoxes, under similar photoperiods, but different environmental conditions. In spring, CAM expression was similar between vegetative and flowering plants, while in autumn, flowering (before anthesis) and fructifying (with fully developed fruit before ripening) plants accumulated more l-malate. Below 100 µmol m(-2) s(-1) , CAM phase I was extended, reducing CAM phase III during the day. Carbon fixation inhibition may occur by two major pathways: nocturnal temperature (pineapple to survive in environments not suitable for high productivity. © 2015 Scandinavian Plant Physiology Society.

Effect of temperature and pH on the actiity of ribulose 1,5-diphosphate carboxylase from the thermophilic hydrogen bacterium Pseudomonas thermophila

Energy Technology Data Exchange (ETDEWEB)

Romanova, A K; Emnova, E E; Zykalova, K A

1980-01-01

The activity of ribulose 1,5-diphosphate (RDP) carboxylase was found in the soluble fraction of the cytoplasm from sonicated Pseudomonas thermophila K-2 cells. The enzyme is relatively thermolabile and completey loses its activity at 80/sup 0/C. The activity of RDP carboxylase at 60/sup 0/C increases by 40% during the first 10 min of heating in the presence of Mg/sup 2 +/ ions, bicarbonate and dithiothreitol, and again decreases if the enzyme is heated over 20 min. The optimum temperature of the enzyme is 50 to 55/sup 0/C. The specific activity of the enzyme in fresh preparations under these conditions reaches 0.22 unit per 1 mg of protein in the extract. The calculated value of the activation energy for RDP carboxylase is 6.4 keal.mole/sup -1/, but 11.6 kcal.mole/sup -1/ in frozen preparations. The optimal pH is 7.0 to 7.3 depending on the buffer. The temperature optimum for the enzyme action does not depend on pH within the range of 7.3 to 8.8. Therefore, RDP carboxylase of Ps, thermophila K-2 differs from RDP carboxylases of mesophilic cultures studied earlier by a higher susceptibility to a decrease in temeprature (the enzyme activity is negligible at 30/sup 0/C), by a lower value of the activation energy at suboptimal temperatures, and by a lower pH optimum of the enzyme action.

The redox state and the phosphorylation state of the mannitol-specific carrier of the E. coli phosphoenolpyruvate-dependent phosphotransferase system

NARCIS (Netherlands)

Robillard, G.T.; Pas, H.H.; Gage, D.; Elferink, M.G.L.

1988-01-01

This review summarizes the recent developments in identifying the activity-linked cysteine as one of the phosphorylation sites on the mannitol-specific EII of the E. coli phosphoenolpyruvate-dependent mannitol transport system. Two phosphorylation sites have been identified, one being the HPr/P-HPr

Nitrate-Dependent Degradation of Acetone by Alicycliphilus and Paracoccus Strains and Comparison of Acetone Carboxylase Enzymes ▿

Science.gov (United States)

Dullius, Carlos Henrique; Chen, Ching-Yuan; Schink, Bernhard

2011-01-01

A novel acetone-degrading, nitrate-reducing bacterium, strain KN Bun08, was isolated from an enrichment culture with butanone and nitrate as the sole sources of carbon and energy. The cells were motile short rods, 0.5 to 1 by 1 to 2 μm in size, which gave Gram-positive staining results in the exponential growth phase and Gram-negative staining results in the stationary-growth phase. Based on 16S rRNA gene sequence analysis, the isolate was assigned to the genus Alicycliphilus. Besides butanone and acetone, the strain used numerous fatty acids as substrates. An ATP-dependent acetone-carboxylating enzyme was enriched from cell extracts of this bacterium and of Alicycliphilus denitrificans K601T by two subsequent DEAE Sepharose column procedures. For comparison, acetone carboxylases were enriched from two additional nitrate-reducing bacterial species, Paracoccus denitrificans and P. pantotrophus. The products of the carboxylase reaction were acetoacetate and AMP rather than ADP. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of cell extracts and of the various enzyme preparations revealed bands corresponding to molecular masses of 85, 78, and 20 kDa, suggesting similarities to the acetone carboxylase enzymes described in detail for the aerobic bacterium Xanthobacter autotrophicus strain Py2 (85.3, 78.3, and 19.6 kDa) and the phototrophic bacterium Rhodobacter capsulatus. Protein bands were excised and compared by mass spectrometry with those of acetone carboxylases of aerobic bacteria. The results document the finding that the nitrate-reducing bacteria studied here use acetone-carboxylating enzymes similar to those of aerobic and phototrophic bacteria. PMID:21841031

Cytosolic Phosphoenolpyruvate Carboxykinase Does Not Solely Control the Rate of Hepatic Gluconeogenesis in the Intact Mouse Liver

OpenAIRE

Burgess, Shawn C.; He, TianTeng; Yan, Zheng; Lindner, Jill; Sherry, A. Dean; Malloy, Craig R.; Browning, Jeffrey D.; Magnuson, Mark A.

2007-01-01

When dietary carbohydrate is unavailable, glucose required to support metabolism in vital tissues is generated via gluconeogenesis in the liver. Expression of phosphoenolpyruvate carboxykinase (PEPCK), commonly considered the control point for liver gluconeogenesis, is normally regulated by circulating hormones to match systemic glucose demand. However, this regulation fails in diabetes. Because other molecular and metabolic factors can also influence gluconeogenesis, the explicit role of PEP...

Effect of abscisic acid and blue radiation on photosynthesis and growth of pea plants

International Nuclear Information System (INIS)

Siedlecka, M.; Romanowska, E.

1993-01-01

The effect of abscisic acid (ABA) on the net photosynthetic rate (PN), the ribulose 1,5-bisphosphate carboxylase (RuBPC) and the phosphoenolpyruvate carboxylase (PEPC) activities, the chlorophyll (Chl) content and growth of pea plants (Pisum sativum) grown under ''white'' (WR) or blue radiation (BR), were investigated. BR as compared to WR enhanced PN, the activities of examined enzymes, and Chl content. In spite of higher PN of the plants grown under BR, dry matter of their shoots was lower in comparison with WR. ABA-treated plants grown under both WR and BR showed reduction in PN. ABA had no effect on the activities of both RuBPC and PEPC and the Chl content. Independent on the radiation quality, ABA reduced stem elongation, but did not affect the biomass of whole shoots

Dicty_cDB: VHB884 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available *nlygsnql yss*np*ktsfnsktrwnk**c*snin*yfnyyf*wyfcwyekywlnynykiliin*lii ikiiiikiiiivlhyfkdaxk*in*kf Translated... 2004.12.24 Homology vs DNA Score E Sequences producing significant alignments: (bits) Value N DQ538352 |DQ538352.1 Bienertia si... aralocaspica phosphoenolpyruvate carboxylase mRNA, partial cds. 48 2e-07 2 DQ538354 |DQ538354.1 Suaeda eltoni...lmekk**n** kh*f*lnhqvkelqns*rni*krlai*virkh*myqecyhiy*i*lmlqnniiwldqlen hsstmkmi*si...tfry*nd**thknykcnlginkt*nsstr**npstfcfns*nlygsnql yss*np*ktsfnsktrwnk**c*snin*yfnyyf*wyfcwyekywlnynykiliin*lii ikiiiikiiiivlhyfkda

Evidence of coexistence of C₃ and C₄ photosynthetic pathways in a green-tide-forming alga, Ulva prolifera.

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Jianfang Xu

Full Text Available Ulva prolifera, a typical green-tide-forming alga, can accumulate a large biomass in a relatively short time period, suggesting that photosynthesis in this organism, particularly its carbon fixation pathway, must be very efficient. Green algae are known to generally perform C₃ photosynthesis, but recent metabolic labeling and genome sequencing data suggest that they may also perform C₄ photosynthesis, so C₄ photosynthesis might be more wide-spread than previously anticipated. Both C₃ and C₄ photosynthesis genes were found in U. prolifera by transcriptome sequencing. We also discovered the key enzymes of C₄ metabolism based on functional analysis, such as pyruvate orthophosphate dikinase (PPDK, phosphoenolpyruvate carboxylase (PEPC, and phosphoenolpyruvate carboxykinase (PCK. To investigate whether the alga operates a C₄-like pathway, the expression of rbcL and PPDK and their enzyme activities were measured under various forms and intensities of stress (differing levels of salinity, light intensity, and temperature. The expression of rbcL and PPDK and their enzyme activities were higher under adverse circumstances. However, under conditions of desiccation, the expression of rbcL and ribulose-1, 5-biphosphate carboxylase (RuBPCase activity was lower, whereas that of PPDK was higher. These results suggest that elevated PPDK activity may alter carbon metabolism and lead to a partial operation of C₄-type carbon metabolism in U. prolifera, probably contributing to its wide distribution and massive, repeated blooms in the Yellow Sea.

Silencing ribulose-1,5-bisphosphate carboxylase/oxygenase expression does not disrupt nitrogen allocation to defense after simulated herbivory in Nicotiana attenuata.

Science.gov (United States)

Stanton, Mariana A; Ullmann-Zeunert, Lynn; Wielsch, Natalie; Bartram, Stefan; Svatoš, Aleš; Baldwin, Ian T; Groten, Karin

2013-01-01

Ribulose-1,5-bisphosphate carboxylase/ oxygenase (RuBisCO) is the most abundant protein on the planet and in addition to its central role in photosynthesis it is thought to function as a nitrogen (N)-storage protein and a potential source of N for defense biosynthesis in plants. In a recent study in the wild tobacco Nicotiana attenuata, we showed that the decrease in absolute N invested in soluble proteins and RuBisCO elicited by simulated herbivory was much larger than the N-requirements of nicotine and phenolamide biosynthesis; (15)N flux studies revealed that N for defensive phenolamide synthesis originates from recently assimilated N rather than from RuBisCO turnover. Here we show that a transgenic line of N. attenuata silenced in the expression of RuBisCO (asRUB) invests similar or even larger amounts of N into phenolamide biosynthesis compared with wild type plants, consistent with our previous conclusion that recently assimilated N is channeled into phenolamide synthesis after elicitation. We suggest that the decrease in leaf proteins after simulated herbivory is a tolerance mechanism, rather than a consequence of N-demand for defense biosynthesis.

Escherichia coli Phosphoenolpyruvate Dependent Phosphotransferase System. NMR Studies of the Conformation of HPr and P-HPr and the Mechanism of Energy Coupling

NARCIS (Netherlands)

Dooijewaard, G.; Roossien, F.F.; Robillard, G.T.

1979-01-01

1H and 31P nuclear magnetic resonance investigations of the phosphoprotein intermediate P-HPr and the parent molecule HPr of the E. coli phosphoenolpyruvate dependent phosphotransferase system (PTS) show that HPr can exist in two conformations. These conformations influence the protonation state of

COH-SR4 reduces body weight, improves glycemic control and prevents hepatic steatosis in high fat diet-induced obese mice.

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James Lester Figarola

Full Text Available Obesity is a chronic metabolic disorder caused by imbalance between energy intake and expenditure, and is one of the principal causative factors in the development of metabolic syndrome, diabetes and cancer. COH-SR4 ("SR4" is a novel investigational compound that has anti-cancer and anti-adipogenic properties. In this study, the effects of SR4 on metabolic alterations in high fat diet (HFD-induced obese C57BL/J6 mice were investigated. Oral feeding of SR4 (5 mg/kg body weight. in HFD mice for 6 weeks significantly reduced body weight, prevented hyperlipidemia and improved glycemic control without affecting food intake. These changes were associated with marked decreases in epididymal fat mass, adipocyte hypertrophy, increased plasma adiponectin and reduced leptin levels. SR4 treatment also decreased liver triglycerides, prevented hepatic steatosis, and normalized liver enzymes. Western blots demonstrated increased AMPK activation in liver and adipose tissues of SR4-treated HFD obese mice, while gene analyses by real time PCR showed COH-SR4 significantly suppressed the mRNA expression of lipogenic genes such as sterol regulatory element binding protein-1c (Srebf1, acetyl-Coenzyme A carboxylase (Acaca, peroxisome proliferator-activated receptor gamma (Pparg, fatty acid synthase (Fasn, stearoyl-Coenzyme A desaturase 1 (Scd1, carnitine palmitoyltransferase 1a (Cpt1a and 3-hydroxy-3-methyl-glutaryl-CoA reductase (Hmgcr, as well as gluconeogenic genes phosphoenolpyruvate carboxykinase 1 (Pck1 and glucose-6-phosphatase (G6pc in the liver of obese mice. In vitro, SR4 activates AMPK independent of upstream kinases liver kinase B1 (LKB1 and Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ. Together, these data suggest that SR4, a novel AMPK activator, may be a promising therapeutic compound for treatment of obesity, fatty liver disease, and related metabolic disorders.

Induction of Cytosolic Acetyl-Coenzyme A Carboxylase in Pea Leaves by Ultraviolet-B Irradiation

OpenAIRE

Tomokazu, Konishi; Takahiro, Kamoi; Ryuichi, Matsuno; Yukiko, Sasaki; Department of Food Science and Technology, Faculty of Agriculture, Kyoto University:(Present)Laboratory of Molecular Genetics, Biotechnology Institute, Akita Prefectural College of Agriculture; Department of Food Science and Technology, Faculty of Agriculture, Kyoto University; Department of Food Science and Technology, Faculty of Agriculture, Kyoto University; Department of Food Science and Technology, Faculty of Agriculture, Kyoto University:(Present)Laboratory of Plant Molecular Biology, School of Agricultural Sciences, Nagoya University

1996-01-01

Levels of subunits of two acetyl-coenzyme A carboxylases were high in small leaves of Pisum sativum, decreased with growth, and remained constant in fully expanded leaves. Irradiation of fully expanded leaves induced the cytosolic isozyme only. This result suggests a key role for the cytosolic enzyme in protection against UV-B.

Silibinin activates AMP-activated protein kinase to protect neuronal cells from oxygen and glucose deprivation-re-oxygenation.

Science.gov (United States)

Xie, Zhi; Ding, Sheng-quan; Shen, Ya-fang

2014-11-14

In this study, we explored the cytoprotective potential of silibinin against oxygen-glucose deprivation (OGD)-induced neuronal cell damages, and studied underling mechanisms. In vitro model of ischemic stroke was created by keeping neuronal cells (SH-SY5Y cells and primary mouse cortical neurons) in an OGD condition followed by re-oxygenation. Pre-treatment of silibinin significantly inhibited OGD/re-oxygenation-induced necrosis and apoptosis of neuronal cells. OGD/re-oxygenation-induced reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) reduction were also inhibited by silibinin. At the molecular level, silibinin treatment in SH-SY5Y cells and primary cortical neurons led to significant AMP-activated protein kinase (AMPK) signaling activation, detected by phosphorylations of AMPKα1, its upstream kinase liver kinase B1 (LKB1) and the downstream target acetyl-CoA Carboxylase (ACC). Pharmacological inhibition or genetic depletion of AMPK alleviated the neuroprotective ability of silibinin against OGD/re-oxygenation. Further, ROS scavenging ability by silibinin was abolished with AMPK inhibition or silencing. While A-769662, the AMPK activator, mimicked silibinin actions and suppressed ROS production and neuronal cell death following OGD/re-oxygenation. Together, these results show that silibinin-mediated neuroprotection requires activation of AMPK signaling. Copyright © 2014 Elsevier Inc. All rights reserved.

Revealing fosfomycin primary effect on Staphylococcus aureus transcriptome: modulation of cell envelope biosynthesis and phosphoenolpyruvate induced starvation

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Gruden Kristina

2010-06-01

Full Text Available Abstract Background Staphylococcus aureus is a highly adaptable human pathogen and there is a constant search for effective antibiotics. Fosfomycin is a potent irreversible inhibitor of MurA, an enolpyruvyl transferase that uses phosphoenolpyruvate as substrate. The goal of this study was to identify the pathways and processes primarily affected by fosfomycin at the genome-wide transcriptome level to aid development of new drugs. Results S. aureus ATCC 29213 cells were treated with sub-MIC concentrations of fosfomycin and harvested at 10, 20 and 40 minutes after treatment. S. aureus GeneChip statistical data analysis was complemented by gene set enrichment analysis. A visualization tool for mapping gene expression data into biological pathways was developed in order to identify the metabolic processes affected by fosfomycin. We have shown that the number of significantly differentially expressed genes in treated cultures increased with time and with increasing fosfomycin concentration. The target pathway - peptidoglycan biosynthesis - was upregulated following fosfomycin treatment. Modulation of transport processes, cofactor biosynthesis, energy metabolism and nucleic acid biosynthesis was also observed. Conclusions Several pathways and genes downregulated by fosfomycin have been identified, in contrast to previously described cell wall active antibiotics, and was explained by starvation response induced by phosphoenolpyruvate accumulation. Transcriptomic profiling, in combination with meta-analysis, has been shown to be a valuable tool in determining bacterial response to a specific antibiotic.

Influence of pH on the /sup 14/C-labelling pattern after photosynthesis of suspended leaf slices and isolated mesophyll cells from chenopodium album in NaH/sup 14/CO/sub 3/

Energy Technology Data Exchange (ETDEWEB)

Baumann, G; Guenther, G [Paedagogische Hochschule Karl Liebknecht, Potsdam (German Democratic Republic). Sektion Chemie/Biologie

1983-01-01

Photosynthetic fixation of /sup 14/C from solutions of NaH/sup 14/CO/sub 3/ (at constant concentrations of free CO/sub 2/) by suspended leaf slices or isolated mesophyll cells from Chenopodium album is increased with increasing pH. Above all, the incorporation of radioactivity into amino acids and malate is stimulated. A direct uptake of HCO/sub 3/ ions and its fixation by PEP carboxylase is suggested. Isolated mesophyll cells showed at pH 7.3 a higher rate of photosynthesis than at pH 5.0.

Characterization of the mycobacterial acyl-CoA carboxylase holo complexes reveals their functional expansion into amino acid catabolism.

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Matthias T Ehebauer

2015-02-01

Full Text Available Biotin-mediated carboxylation of short-chain fatty acid coenzyme A esters is a key step in lipid biosynthesis that is carried out by multienzyme complexes to extend fatty acids by one methylene group. Pathogenic mycobacteria have an unusually high redundancy of carboxyltransferase genes and biotin carboxylase genes, creating multiple combinations of protein/protein complexes of unknown overall composition and functional readout. By combining pull-down assays with mass spectrometry, we identified nine binary protein/protein interactions and four validated holo acyl-coenzyme A carboxylase complexes. We investigated one of these--the AccD1-AccA1 complex from Mycobacterium tuberculosis with hitherto unknown physiological function. Using genetics, metabolomics and biochemistry we found that this complex is involved in branched amino-acid catabolism with methylcrotonyl coenzyme A as the substrate. We then determined its overall architecture by electron microscopy and found it to be a four-layered dodecameric arrangement that matches the overall dimensions of a distantly related methylcrotonyl coenzyme A holo complex. Our data argue in favor of distinct structural requirements for biotin-mediated γ-carboxylation of α-β unsaturated acid esters and will advance the categorization of acyl-coenzyme A carboxylase complexes. Knowledge about the underlying structural/functional relationships will be crucial to make the target category amenable for future biomedical applications.

Biotin carboxylases in mitochondria and the cytosol from skeletal and cardiac muscle as detected by avidin binding

NARCIS (Netherlands)

Kirkeby, S.; Moe, D.; Bøg-Hansen, T. C.; van Noorden, C. J.

1993-01-01

Biotin carboxylases in mammalian cells are regulatory enzymes in lipogenesis and gluconeogenesis. In this study, endogenous biotin in skeletal and cardiac muscle was detected using avidin conjugated with alkaline phosphatase and applied in high concentrations to muscle sections. The avidin binding

Hydrogen sulphide improves adaptation of Zea mays seedlings to iron deficiency.

Science.gov (United States)

Chen, Juan; Wu, Fei-Hua; Shang, Yu-Ting; Wang, Wen-Hua; Hu, Wen-Jun; Simon, Martin; Liu, Xiang; Shangguan, Zhou-Ping; Zheng, Hai-Lei

2015-11-01

Hydrogen sulphide (H2S) is emerging as a potential molecule involved in physiological regulation in plants. However, whether H2S regulates iron-shortage responses in plants is largely unknown. Here, the role of H2S in modulating iron availability in maize (Zea mays L. cv Canner) seedlings grown in iron-deficient culture solution is reported. The main results are as follows: Firstly, NaHS, a donor of H2S, completely prevented leaf interveinal chlorosis in maize seedlings grown in iron-deficient culture solution. Secondly, electron micrographs of mesophyll cells from iron-deficient maize seedlings revealed plastids with few photosynthetic lamellae and rudimentary grana. On the contrary, mesophyll chloroplasts appeared completely developed in H2S-treated maize seedlings. Thirdly, H2S treatment increased iron accumulation in maize seedlings by changing the expression levels of iron homeostasis- and sulphur metabolism-related genes. Fourthly, phytosiderophore (PS) accumulation and secretion were enhanced by H2S treatment in seedlings grown in iron-deficient solution. Indeed, the gene expression of ferric-phytosiderophore transporter (ZmYS1) was specifically induced by iron deficiency in maize leaves and roots, whereas their abundance was decreased by NaHS treatment. Lastly, H2S significantly enhanced photosynthesis through promoting the protein expression of ribulose-1,5-bisphosphate carboxylase large subunit (RuBISCO LSU) and phosphoenolpyruvate carboxylase (PEPC) and the expression of genes encoding RuBISCO large subunit (RBCL), small subunit (RBCS), D1 protein (psbA), and PEPC in maize seedlings grown in iron-deficient solution. These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and consequently increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Acetyl-CoA carboxylase rewires cancer metabolism to allow cancer cells to survive inhibition of the Warburg effect by cetuximab.

Science.gov (United States)

Luo, Jingtao; Hong, Yun; Lu, Yang; Qiu, Songbo; Chaganty, Bharat K R; Zhang, Lun; Wang, Xudong; Li, Qiang; Fan, Zhen

2017-01-01

Cetuximab inhibits HIF-1-regulated glycolysis in cancer cells, thereby reversing the Warburg effect and leading to inhibition of cancer cell metabolism. AMP-activated protein kinase (AMPK) is activated after cetuximab treatment, and a sustained AMPK activity is a mechanism contributing to cetuximab resistance. Here, we investigated how acetyl-CoA carboxylase (ACC), a downstream target of AMPK, rewires cancer metabolism in response to cetuximab treatment. We found that introduction of experimental ACC mutants lacking the AMPK phosphorylation sites (ACC1_S79A and ACC2_S212A) into head and neck squamous cell carcinoma (HNSCC) cells protected HNSCC cells from cetuximab-induced growth inhibition. HNSCC cells with acquired cetuximab resistance contained not only high levels of T172-phosphorylated AMPK and S79-phosphorylated ACC1 but also an increased level of total ACC. These findings were corroborated in tumor specimens of HNSCC patients treated with cetuximab. Cetuximab plus TOFA (an allosteric inhibitor of ACC) achieved remarkable growth inhibition of cetuximab-resistant HNSCC xenografts. Our data suggest a novel paradigm in which cetuximab-mediated activation of AMPK and subsequent phosphorylation and inhibition of ACC is followed by a compensatory increase in total ACC, which rewires cancer metabolism from glycolysis-dependent to lipogenesis-dependent. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Isolation of nucleotide binding site-leucine rich repeat and kinase resistance gene analogues from sugarcane (Saccharum spp.).

Science.gov (United States)

Glynn, Neil C; Comstock, Jack C; Sood, Sushma G; Dang, Phat M; Chaparro, Jose X

2008-01-01

Resistance gene analogues (RGAs) have been isolated from many crops and offer potential in breeding for disease resistance through marker-assisted selection, either as closely linked or as perfect markers. Many R-gene sequences contain kinase domains, and indeed kinase genes have been reported as being proximal to R-genes, making kinase analogues an additionally promising target. The first step towards utilizing RGAs as markers for disease resistance is isolation and characterization of the sequences. Sugarcane clone US01-1158 was identified as resistant to yellow leaf caused by the sugarcane yellow leaf virus (SCYLV) and moderately resistant to rust caused by Puccinia melanocephala Sydow & Sydow. Degenerate primers that had previously proved useful for isolating RGAs and kinase analogues in wheat and soybean were used to amplify DNA from sugarcane (Saccharum spp.) clone US-01-1158. Sequences generated from 1512 positive clones were assembled into 134 contigs of between two and 105 sequences. Comparison of the contig consensuses with the NCBI sequence database using BLASTx showed that 20 had sequence homology to nuclear binding site and leucine rich repeat (NBS-LRR) RGAs, and eight to kinase genes. Alignment of the deduced amino acid sequences with similar sequences from the NCBI database allowed the identification of several conserved domains. The alignment and resulting phenetic tree showed that many of the sequences had greater similarity to sequences from other species than to one another. The use of degenerate primers is a useful method for isolating novel sugarcane RGA and kinase gene analogues. Further studies are needed to evaluate the role of these genes in disease resistance.

PGC-1alpha in exercise- and exercise training-induced metabolic adaptations

DEFF Research Database (Denmark)

Jørgensen, Stine Ringholm

and interferes with the exercise-induced adaptive response in human skeletal muscle. Study II demonstrates that mouse liver glucose-6-phosphatase (G6Pase) mRNA content increased in recovery from acute exercise in both wildtype (WT) and PGC-1α knockout (KO) mice, while phosphoenolpyruvate carboxykinase (PEPCK......) and pyruvate carboxylase mRNA content did not change in either genotype. Exercise training increased PEPCK protein content in both WT and PGC-1α KO mice. In addition, the mRNA and protein content of cytochrome (Cyt) c and cytochrome c oxidase (COX) subunit I increased in response to acute exercise and exercise...

Purification and Characterization of the Acetone Carboxylase of Cupriavidus metallidurans Strain CH34

Science.gov (United States)

Rosier, Caroline; Leys, Natalie; Henoumont, Céline; Mergeay, Max

2012-01-01

Acetone carboxylase (Acx) is a key enzyme involved in the biodegradation of acetone by bacteria. Except for the Helicobacteraceae family, genome analyses revealed that bacteria that possess an Acx, such as Cupriavidus metallidurans strain CH34, are associated with soil. The Acx of CH34 forms the heterohexameric complex α2β2γ2 and can carboxylate only acetone and 2-butanone in an ATP-dependent reaction to acetoacetate and 3-keto-2-methylbutyrate, respectively. PMID:22492439

Hepatic transcriptional changes in critical genes for gluconeogenesis following castration of bulls

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Dilla Mareistia Fassah

2018-04-01

Full Text Available Objective This study was performed to understand transcriptional changes in the genes involved in gluconeogenesis and glycolysis pathways following castration of bulls. Methods Twenty Korean bulls were weaned at average 3 months of age, and castrated at 6 months. Liver tissues were collected from bulls (n = 10 and steers (n = 10 of Korean cattle, and hepatic gene expression levels were measured using quantitative real-time polymerase chain reaction. We examined hepatic transcription levels of genes encoding enzymes for irreversible reactions in both gluconeogenesis and glycolysis as well as genes encoding enzymes for the utilization of several glucogenic substrates. Correlations between hepatic gene expression and carcass characteristics were performed to understand their associations. Results Castration increased the mRNA (3.6 fold; p<0.01 and protein levels (1.4 fold; p< 0.05 of pyruvate carboxylase and mitochondrial phosphoenolpyruvate carboxykinase genes (1.7 fold; p<0.05. Hepatic mRNA levels of genes encoding the glycolysis enzymes were not changed by castration. Castration increased mRNA levels of both lactate dehydrogenase A (1.5 fold; p<0.05 and lactate dehydrogenase B (2.2 fold; p<0.01 genes for lactate utilization. Castration increased mRNA levels of glycerol kinase (2.7 fold; p<0.05 and glycerol-3-phosphate dehydrogenase 1 (1.5 fold; p<0.05 genes for glycerol utilization. Castration also increased mRNA levels of propionyl-CoA carboxylase beta (mitochondrial (3.5 fold; p<0.01 and acyl-CoA synthetase short chain family member 3 (1.3 fold; p = 0.06 genes for propionate incorporation. Conclusion Castration increases transcription levels of critical genes coding for enzymes involved in irreversible gluconeogenesis reactions from pyruvate to glucose and enzymes responsible for incorporation of glucogenic substrates including lactate, glycerol, and propionate. Hepatic gluconeogenic gene expression levels were associated with intramuscular

Cytosolic phosphoenolpyruvate carboxykinase is a response gene involved in porcine adipocyte adaptation to heat stress.

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Qu, Huan; Ajuwon, Kolapo M

2018-05-04

Heat stress (HS) leads to increased lipid storage and expression of cytosolic phosphoenolpyruvate carboxykinase (PCK1) in pig adipocytes. However, the importance of PCK1 activation and lipid storage in the adaptive response to HS is unknown. Therefore, in vitro experiments were conducted to investigate the effect of PCK1 inhibition with 3-mercaptopicolinic acid (3MPA) on lipid storage and adipocyte response during HS. In vitro culture of adipocytes under HS (41.0 °C) increased (P cultured adipocytes were less able to induce adaptive responses such as upregulation of HSP70 and triglycerides, and this exacerbated ER stress during HS. Thus, PCK1 may function to alleviate ER stress that occurs during HS.

Glycogen Synthase Kinase-3 regulates IGFBP-1 gene transcription through the Thymine-rich Insulin Response Element

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Marquez Rodolfo

2004-09-01

Full Text Available Abstract Background Hepatic expression of several gene products involved in glucose metabolism, including phosphoenolpyruvate carboxykinase (PEPCK, glucose-6-phosphatase (G6Pase and insulin-like growth factor binding protein-1 (IGFBP-1, is rapidly and completely inhibited by insulin. This inhibition is mediated through the regulation of a DNA element present in each of these gene promoters, that we call the Thymine-rich Insulin Response Element (TIRE. The insulin signalling pathway that results in the inhibition of these gene promoters requires the activation of phosphatidylinositol 3-kinase (PI 3-kinase. However, the molecules that connect PI 3-kinase to these gene promoters are not yet fully defined. Glycogen Synthase Kinase 3 (GSK-3 is inhibited following activation of PI 3-kinase. We have shown previously that inhibitors of GSK-3 reduce the activity of two TIRE-containing gene promoters (PEPCK and G6Pase, whose products are required for gluconeogenesis. Results In this report we demonstrate that in H4IIE-C3 cells, four distinct classes of GSK-3 inhibitor mimic the effect of insulin on a third TIRE-containing gene, IGFBP-1. We identify the TIRE as the minimum requirement for inhibition by these agents, and demonstrate that the target of GSK-3 is unlikely to be the postulated TIRE-binding protein FOXO-1. Importantly, overexpression of GSK-3 in cells reduces the insulin regulation of TIRE activity as well as endogenous IGFBP-1 expression. Conclusions These results implicate GSK-3 as an intermediate in the pathway from the insulin receptor to the TIRE. Indeed, this is the first demonstration of an absolute requirement for GSK-3 inhibition in insulin regulation of gene transcription. These data support the potential use of GSK-3 inhibitors in the treatment of insulin resistant states such as Type 2 diabetes mellitus, but suggest that it will be important to identify all TIRE-containing genes to assess potential side effects of these agents.

A novel ATP-generating machinery to counter nitrosative stress is mediated by substrate-level phosphorylation.

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Auger, Christopher; Appanna, Vasu D

2015-01-01

It is well-known that elevated amounts of nitric oxide and other reactive nitrogen species (RNS) impact negatively on the tricarboxylic acid (TCA) cycle and oxidative phosphorylation. These perturbations severely compromise O2-dependent energy production. While bacteria are known to adapt to RNS, a key tool employed by macrophages to combat infections, the exact mechanisms are unknown. The bacterium was cultured in a defined mineral medium and cell-free extracts obtained at the same growth phase were utilized for various biochemical studies Blue native polyacrylamide gel electrophoresis followed by in-gel activity assays, high performance liquid chromatography and co-immunoprecipitaton are applied to investigate the effects of RNS on the model microbe Pseudomonas fluorescens. Citrate is channeled away from the tricarboxylic acid cycle using a novel metabolon consisting of citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate phosphate dikinase (PPDK). This metabolic engine comprising three disparate enzymes appears to transiently assemble as a supercomplex aimed at ATP synthesis. The up-regulation in the activities of adenylate kinase (AK) and nucleoside diphosphate kinase (NDPK) ensured the efficacy of this ATP-making machine. Microbes may escape the effects of nitrosative stress by re-engineering metabolic networks in order to generate and store ATP anaerobically when the electron transport chain is defective. The molecular configuration described herein provides further understanding of how metabolism plays a key role in the adaptation to nitrosative stress and reveals novel targets that will inform the development of antimicrobial agents to counter RNS-resistant pathogens. Copyright © 2014 Elsevier B.V. All rights reserved.

Identification of the large subunit of Ribulose 1,5-bisphosphate carboxylase/oxygenase as a substrate for transglutaminase in Medicageo sativa L. (alfalfa)

International Nuclear Information System (INIS)

Margosiak, S.A.; Dharma, A.; Carver, M.R.B.; Gonzales, A.P.; Louie, D.; Kuehn, G.D.

1990-01-01

Extract prepared from floral meristematic tissue of alfalfa (Medicago sativa L.) were investigated for expression of the enzyme transglutaminase in order to identify the major protein substrate for transglutaminase-directed modifications among plant proteins. The large polymorphic subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase in alfalfa, with molecular weights of 52,700 and 57,600, are major substrates for transglutaminase in these extracts. This was established by: (a) covalent conjugation of monodansylcadaverine to the large subunit followed by fluorescent detection in SDS-polyacrylamide gels; (b) covalent conjugation of [ 14 C]putrescine to the large subunit with detection by autoradiography; (c) covalent conjugation of monodansylcadaverine to the large subunit and demonstration of immunocross-reactivity on nitrocellulose transblot of the modified large subunit with antibody prepared in rabbits against dansylated-ovalbumin; (d) demonstration of a direct dependence of the rate of transglutaminase-mediated, [ 14 C]putresciene incorporation upon the concentration of ribulose, 1,5-bisphosphate carboxylase/oxygenase from alfalfa or spinach; and (e) presumptive evidence from size exclusion chromatography that transglutaminase may cofractionate with native molecules of ribulose 1,5-bisphosphate carboxylase/oxygenase in crude extracts

Reticulate leaves and stunted roots are independent phenotypes pointing at opposite roles of the phosphoenolpyruvate/phosphate translocator defective in cue1 in the plastids of both organs

Czech Academy of Sciences Publication Activity Database

Staehr, P.; Loettgert, T.; Christmann, A.; Krueger, S.; Rosar, Ch.; Rolčík, Jakub; Novák, Ondřej; Strnad, Miroslav; Bell, K.; Weber, A.P.M.; Fluegge, U-I.; Haeusler, R.E.

2014-01-01

Roč. 5, APR 2014 (2014) ISSN 1664-462X R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : secondary metabolism * phosphate translocator * phosphoenolpyruvate Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.948, year: 2014

Anaplerotic roles of pyruvate carboxylase in mammalian tissues.

Science.gov (United States)

Jitrapakdee, S; Vidal-Puig, A; Wallace, J C

2006-04-01

Pyruvate carboxylase (PC) catalyzes the ATP-dependent carboxylation of pyruvate to oxaloacetate. PC serves an anaplerotic role for the tricarboxylic acid cycle, when intermediates are removed for different biosynthetic purposes. In liver and kidney, PC provides oxaloacetate for gluconeogenesis. In adipocytes PC is involved in de novo fatty acid synthesis and glyceroneogenesis, and is regulated by the peroxisome proliferator-activated receptor-gamma, suggesting that PC is involved in the metabolic switch controlling fuel partitioning toward lipogenesis. In islets, PC is necessary for glucose-induced insulin secretion by providing oxaloacetate to form malate that participates in the 'pyruvate/malate cycle' to shuttle 3C or 4C between mitochondria and cytoplasm. Hyperglycemia and hyperlipidemia impair this cycle and affect glucose-stimulated insulin release. In astrocytes, PC is important for de novo synthesis of glutamate, an important excitatory neurotransmitter supplied to neurons. Transcriptional studies of the PC gene pinpoint some transcription factors that determine tissue-specific expression.

C75, a fatty acid synthase inhibitor, modulates AMP-activated protein kinase to alter neuronal energy metabolism.

Science.gov (United States)

Landree, Leslie E; Hanlon, Andrea L; Strong, David W; Rumbaugh, Gavin; Miller, Ian M; Thupari, Jagan N; Connolly, Erin C; Huganir, Richard L; Richardson, Christine; Witters, Lee A; Kuhajda, Francis P; Ronnett, Gabriele V

2004-01-30

C75, a synthetic inhibitor of fatty acid synthase (FAS), is hypothesized to alter the metabolism of neurons in the hypothalamus that regulate feeding behavior to contribute to the decreased food intake and profound weight loss seen with C75 treatment. In the present study, we characterize the suitability of primary cultures of cortical neurons for studies designed to investigate the consequences of C75 treatment and the alteration of fatty acid metabolism in neurons. We demonstrate that in primary cortical neurons, C75 inhibits FAS activity and stimulates carnitine palmitoyltransferase-1 (CPT-1), consistent with its effects in peripheral tissues. C75 alters neuronal ATP levels and AMP-activated protein kinase (AMPK) activity. Neuronal ATP levels are affected in a biphasic manner with C75 treatment, decreasing initially, followed by a prolonged increase above control levels. Cerulenin, a FAS inhibitor, causes a similar biphasic change in ATP levels, although levels do not exceed control. C75 and cerulenin modulate AMPK phosphorylation and activity. TOFA, an inhibitor of acetyl-CoA carboxylase, increases ATP levels, but does not affect AMPK activity. Several downstream pathways are affected by C75 treatment, including glucose metabolism and acetyl-CoA carboxylase (ACC) phosphorylation. These data demonstrate that C75 modulates the levels of energy intermediates, thus, affecting the energy sensor AMPK. Similar effects in hypothalamic neurons could form the basis for the effects of C75 on feeding behavior.

Inhibition of E. coli P-enolpyruvate carboxylase by P-enol-3-bromopyruvate

International Nuclear Information System (INIS)

Asem, K.; Smith, T.E.

1986-01-01

The generality of the mechanism based inhibition of P-enolpyruvate carboxylases (PEPCase) by P-enol-3-bromopyruvate (BrPEP) was tested by measuring its effects on the allosterically regulated enzyme from E. coli. In the presence of 1mM Mn 2+ , BrPEP appears to be a competitive inhibitor (K/sub i/ = 0.0087mM) of PEPCase. Incubation of 0.005mM PEPCase with 0.5mM (or 1.0mM)BrPEP along with H 14 CO 3 - and Mn 2+ , yielded, upon reduction with NaBH 4 , a protein containing radioactivity in an amount approximately proportional to that expected from the loss of catalytic activity. At both a 25- and a 50-fold excess (0.5mM and 1.0mM, respectively) of BrPEP to PEPCase subunits, first order loss of activity occurred with k values of 5.24 x 10 -3 min -1 and 1.03 x 10 -2 min -1 , respectively. At the lower concentration of BrPEP the inactivation process appeared to be reversible after 40 min with no further inhibition occurring even up to two hours of incubation. At the higher concentration of BrPEP, the rate of inhibition slowed dramatically after 50 min and appeared insignificant over the next hour. These data suggest that BrPEP irreversibly inactivates the E. coli PEP carboxylase, but that there may be considerable dissociation of the product, Br-oxaloacetate, before irreversible binding occurs, and that the reduced rate of inactivation may be due to depletion of BrPEP

Stevioside improves pancreatic beta-cell function during glucotoxicity via regulation of acetyl-CoA carboxylase.

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Chen, Jianguo; Jeppesen, Per Bendix; Nordentoft, Iver; Hermansen, Kjeld

2007-06-01

Chronic hyperglycemia is detrimental to pancreatic beta-cells, causing impaired insulin secretion and beta-cell turnover. The characteristic secretory defects are increased basal insulin secretion (BIS) and a selective loss of glucose-stimulated insulin secretion (GSIS). Several recent studies support the view that the acetyl-CoA carboxylase (ACC) plays a pivotal role for GSIS. We have shown that stevioside (SVS) enhances insulin secretion and ACC gene expression. Whether glucotoxicity influences ACC and whether this action can be counteracted by SVS are not known. To investigate this, we exposed isolated mouse islets as well as clonal INS-1E beta-cells for 48 h to 27 or 16.7 mM glucose, respectively. We found that 48-h exposure to high glucose impairs GSIS from mouse islets and INS-1E cells, an effect that is partly counteracted by SVS. The ACC dephosphorylation inhibitor okadaic acid (OKA, 10(-8) M), and 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR, 10(-4) M), an activator of 5'-AMP protein kinase that phosphorylates ACC, eliminated the beneficial effect of SVS. 5-Tetrade-cyloxy-2-furancarboxylic acid (TOFA), the specific ACC inhibitor, blocked the effect of SVS as well. During glucotoxity, ACC gene expression, ACC protein, and phosphorylated ACC protein were increased in INS-1E beta-cells. SVS pretreatment further increased ACC gene expression with strikingly elevated ACC activity and increased glucose uptake accompanied by enhanced GSIS. Our studies show that glucose is a potent stimulator of ACC and that SVS to some extent counteracts glucotoxicity via increased ACC activity. SVS possesses the potential to alleviate negative effects of glucotoxicity in beta-cells via a unique mechanism of action.

AMPK activation represses the human gene promoter of the cardiac isoform of acetyl-CoA carboxylase: Role of nuclear respiratory factor-1

Energy Technology Data Exchange (ETDEWEB)

Adam, Tasneem; Opie, Lionel H. [Hatter Cardiovascular Research Institute, Faculty of Health Sciences, University of Cape Town, Observatory 7925 (South Africa); Essop, M. Faadiel, E-mail: mfessop@sun.ac.za [Cardio-Metabolic Research Group (CMRG), Department of Physiological Sciences, Stellenbosch University, Stellenbosch 7600 (South Africa)

2010-07-30

Research highlights: {yields} AMPK inhibits acetyl-CoA carboxylase beta gene promoter activity. {yields} Nuclear respiratory factor-1 inhibits acetyl-CoA carboxylase beta promoter activity. {yields} AMPK regulates acetyl-CoA carboxylase beta at transcriptional level. -- Abstract: The cardiac-enriched isoform of acetyl-CoA carboxylase (ACC{beta}) produces malonyl-CoA, a potent inhibitor of carnitine palmitoyltransferase-1. AMPK inhibits ACC{beta} activity, lowering malonyl-CoA levels and promoting mitochondrial fatty acid {beta}-oxidation. Previously, AMPK increased promoter binding of nuclear respiratory factor-1 (NRF-1), a pivotal transcriptional modulator controlling gene expression of mitochondrial proteins. We therefore hypothesized that NRF-1 inhibits myocardial ACC{beta} promoter activity via AMPK activation. A human ACC{beta} promoter-luciferase construct was transiently transfected into neonatal cardiomyocytes {+-} a NRF-1 expression construct. NRF-1 overexpression decreased ACC{beta} gene promoter activity by 71 {+-} 4.6% (p < 0.001 vs. control). Transfections with 5'-end serial promoter deletions revealed that NRF-1-mediated repression of ACC{beta} was abolished with a pPII{beta}-18/+65-Luc deletion construct. AMPK activation dose-dependently reduced ACC{beta} promoter activity, while NRF-1 addition did not further decrease it. We also investigated NRF-1 inhibition in the presence of upstream stimulatory factor 1 (USF1), a known transactivator of the human ACC{beta} gene promoter. Here NRF-1 blunted USF1-dependent induction of ACC{beta} promoter activity by 58 {+-} 7.5% (p < 0.001 vs. control), reversed with a dominant negative NRF-1 construct. NRF-1 also suppressed endogenous USF1 transcriptional activity by 55 {+-} 6.2% (p < 0.001 vs. control). This study demonstrates that NRF-1 is a novel transcriptional inhibitor of the human ACC{beta} gene promoter in the mammalian heart. Our data extends AMPK regulation of ACC{beta} to the transcriptional level.

Immunochemical localization of ribulose-1,5-bisphosphate carboxylase in the symbiont-containing gills of Solemya velum (Bivalvia : Mollusca)

NARCIS (Netherlands)

Cavanaugh, Colleen M.; Abbott, Marilyn S.; Veenhuis, Marten

1988-01-01

The distribution of the Calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase (RbuP2Case; EC 4.1.1.39) was examined by using two immunological methods in tissues of Solemya velum, an Atlantic coast bivalve containing putative chemoautotrophic symbionts. Antibodies elicited by the purified large

Relationships of leaf dark respiration to leaf nitrogen, specific leaf area and leaf life-span: a test across biomes and functional groups.

Science.gov (United States)

Reich, Peter B; Walters, Michael B; Ellsworth, David S; Vose, James M; Volin, John C; Gresham, Charles; Bowman, William D

1998-05-01

Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf dark respiration rate (R d ) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic capacity (A max ). However, it is not known whether such scaling, if it exists, is similar among disparate biomes and plant functional types. We tested this idea by examining the interspecific relationships between R d measured at a standard temperature and leaf life-span, N, SLA and A max for 69 species from four functional groups (forbs, broad-leafed trees and shrubs, and needle-leafed conifers) in six biomes traversing the Americas: alpine tundra/subalpine forest, Colorado; cold temperate forest/grassland, Wisconsin; cool temperate forest, North Carolina; desert/shrubland, New Mexico; subtropical forest, South Carolina; and tropical rain forest, Amazonas, Venezuela. Area-based R d was positively related to area-based leaf N within functional groups and for all species pooled, but not when comparing among species within any site. At all sites, mass-based R d (R d-mass ) decreased sharply with increasing leaf life-span and was positively related to SLA and mass-based A max and leaf N (leaf N mass ). These intra-biome relationships were similar in shape and slope among sites, where in each case we compared species belonging to different plant functional groups. Significant R d-mass -N mass relationships were observed in all functional groups (pooled across sites), but the relationships differed, with higher R d at any given leaf N in functional groups (such as forbs) with higher SLA and shorter leaf life-span. Regardless of biome or functional group, R d-mass was well predicted by all combinations of leaf life-span, N mass and/or SLA (r 2 ≥ 0.79, P morphological, chemical and metabolic traits.

Genome sequence of carboxylesterase, carboxylase and xylose isomerase producing alkaliphilic haloarchaeon Haloterrigena turkmenica WANU15

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Samy Selim

2016-03-01

Full Text Available We report draft genome sequence of Haloterrigena turkmenica strain WANU15, isolated from Soda Lake. The draft genome size is 2,950,899 bp with a G + C content of 64% and contains 49 RNA sequence. The genome sequence can be accessed at DDBJ/EMBL/GenBank under the accession no. LKCV00000000. Keywords: Soda Lake, Haloterrigena turkmenica, Carboxylesterase, Carboxylase, Xylose isomerase, Whole genome sequencing

Leaf-IT: An Android application for measuring leaf area.

Science.gov (United States)

Schrader, Julian; Pillar, Giso; Kreft, Holger

2017-11-01

The use of plant functional traits has become increasingly popular in ecological studies because plant functional traits help to understand key ecological processes in plant species and communities. This also includes changes in diversity, inter- and intraspecific interactions, and relationships of species at different spatiotemporal scales. Leaf traits are among the most important traits as they describe key dimensions of a plant's life history strategy. Further, leaf area is a key parameter with relevance for other traits such as specific leaf area, which in turn correlates with leaf chemical composition, photosynthetic rate, leaf longevity, and carbon investment. Measuring leaf area usually involves the use of scanners and commercial software and can be difficult under field conditions. We present Leaf-IT, a new smartphone application for measuring leaf area and other trait-related areas. Leaf-IT is free, designed for scientific purposes, and runs on Android 4 or higher. We tested the precision and accuracy using objects with standardized area and compared the area measurements of real leaves with the well-established, commercial software WinFOLIA using the Altman-Bland method. Area measurements of standardized objects show that Leaf-IT measures area with high accuracy and precision. Area measurements with Leaf-IT of real leaves are comparable to those of WinFOLIA. Leaf-IT is an easy-to-use application running on a wide range of smartphones. That increases the portability and use of Leaf-IT and makes it possible to measure leaf area under field conditions typical for remote locations. Its high accuracy and precision are similar to WinFOLIA. Currently, its main limitation is margin detection of damaged leaves or complex leaf morphologies.

Increased expression of pyruvate carboxylase and biotin protein ligase increases lysine production in a biotin prototrophic Corynebacterium glutamicum strain

DEFF Research Database (Denmark)

Wang, Zhihao; Moslehi-Jenabian, Soloomeh; Solem, Christian

2015-01-01

, and achieved biotin prototrophy. We found that AHP-3, containing pBIO, was able to produce lysine in a medium lacking biotin and that the lysine yield on glucose was similar to what is obtained when using a medium containing biotin. However, there was a decrease in specific growth rate of 20% when the strain...... pimeloyl-Acyl Carrier Protein [ACP]) formation. Pyruvate carboxylase (pycA), a biotin-dependent enzyme needed for lysine biosynthesis and biotin ligase (birA), which is responsible for attaching biotin to pyruvate carboxylase, were overexpressed by replacing the native promoters with the strong superoxide...... dismutase (sod) promoter, to see whether growth could be restored. Neither pycA nor birA overexpression, whether alone or in combination, had an effect on specific growth rate, but they did have a positive effect on lysine yield, which increased by 55% in the strain overexpressing both enzymes....

Comparative Physiological and Proteomic Analysis Reveals the Leaf Response to Cadmium-Induced Stress in Poplar (Populus yunnanensis.

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Yunqiang Yang

Full Text Available Excess amounts of heavy metals are important environmental pollutants with significant ecological and nutritional effects. Cdmium (Cd is of particular concern because of its widespread occurrence and high toxicity. We conducted physiological and proteomic analyses to improve our understanding of the responses of Populus yunnanensis to Cd stress. The plantlets experienced two apparent stages in their response to Cd stress. During the first stage, transiently induced defense-response molecules, photosynthesis- and energy-associated proteins, antioxidant enzymes and heat shock proteins (HSPs accumulated to enhance protein stability and establish a new cellular homeostasis. This activity explains why plant photosynthetic capability during this period barely changed. During the second stage, a decline of ribulose-1, 5-bisphosphate carboxylase (RuBisCO and HSP levels led to imbalance of the plant photosynthetic system. Additionally, the expression of Mitogen-activated protein kinase 3 (MPK3, Mitogen-activated protein kinase 6 (MPK6 and a homeobox-leucine zipper protein was higher in the second stage. Higher expression of caffeoyl-CoA O-methyltransferase (CCoAOMT may regulate plant cell wall synthesis for greater Cd storage. These genes may be candidates for further research and use in genetic manipulation of poplar tolerance to Cd stress.

Control of Lactose Transport, β-Galactosidase Activity, and Glycolysis by CcpA in Streptococcus thermophilus : Evidence for Carbon Catabolite Repression by a Non-Phosphoenolpyruvate-Dependent Phosphotransferase System Sugar

NARCIS (Netherlands)

Bogaard, Patrick T.C. van den; Kleerebezem, Michiel; Kuipers, Oscar P.; Vos, Willem M. de

2000-01-01

Streptococcus thermophilus, unlike many other gram-positive bacteria, prefers lactose over glucose as the primary carbon and energy source. Moreover, lactose is not taken up by a phosphoenolpyruvate-dependent phosphotransferase system (PTS) but by the dedicated transporter LacS. In this paper we

Effects of lead arsenate sprays on the fruit growth and sugar and acid contents in Natsudaidai (Citrus natsudaidai Hayata)

Energy Technology Data Exchange (ETDEWEB)

Kadoya, K; Kuraoka, T; Matsumoto, K

1965-01-01

The juice of the fruit of Citrus natsudaidai is characterized by high acidity. The acidity of the juice was most effectively reduced by treatment with lead arsenate spray at an early fruit growth stage when the acids were being most actively formed. The water-soluble organic acid content of leaves was not affected. The sugar content of the juice was increased by the treatment. The activity of phosphoenolpyruvate carboxylase was lowered in the vesicles of fruit sprayed with lead arsenate. It was also much depressed in the extracts from normal fruit when arsenic trioxide was added. Arsenic was detected in the vesicles of treated fruit. 15 references, 9 figures.

Interactive response of photosynthetic characteristics in Haloxylon ammodendron and Hedysarum scoparium exposed to soil water and air vapor pressure deficits.

Science.gov (United States)

Gong, Chunmei; Wang, Jiajia; Hu, Congxia; Wang, Junhui; Ning, Pengbo; Bai, Juan

2015-08-01

C4 plants possess better drought tolerance than C3 plants. However, Hedysarum scoparium, a C3 species, is dominant and widely distributed in the desert areas of northwestern China due to its strong drought tolerance. This study compared it with Haloxylon ammodendron, a C4 species, regarding the interactive effects of drought stress and different leaf-air vapor pressure deficits. Variables of interest included gas exchange, the activity levels of key C4 photosynthetic enzymes, and cellular anatomy. In both species, gas exchange parameters were more sensitive to high vapor pressure deficit than to strong water stress, and the net CO2 assimilation rate (An) was enhanced as vapor pressure deficits increased. A close relationship between An and stomatal conductance (gs) suggested that the species shared a similar response mechanism. In H. ammodendron, the activity levels of key C4 enzymes were higher, including those of phosphoenolpyruvate carboxylase (PEPC) and nicotinamide adenine dinucleotide phosphate-malate enzyme (NADP-ME), whereas in H. scoparium, the activity level of nicotinamide adenine dinucleotide-malate enzyme (NAD-ME) was higher. Meanwhile, H. scoparium utilized adaptive structural features, including a larger relative vessel area and a shorter distance from vein to stomata, which facilitated the movement of water. These findings implied that some C4 biochemical pathways were present in H. scoparium to respond to environmental challenges. Copyright © 2015. Published by Elsevier B.V.

Magnolol Alleviates Inflammatory Responses and Lipid Accumulation by AMP-Activated Protein Kinase-Dependent Peroxisome Proliferator-Activated Receptor α Activation

Directory of Open Access Journals (Sweden)

Ye Tian

2018-02-01

Full Text Available Magnolol (MG is a kind of lignin isolated from Magnolia officinalis, which serves several different biological functions, such as antifungal, anticancer, antioxidant, and hepatoprotective functions. This study aimed to evaluate the protective effect of MG against oleic acid (OA-induced hepatic steatosis and inflammatory damage in HepG2 cells and in a tyloxapol (Ty-induced hyperlipidemia mouse model. Our findings indicated that MG can effectively inhibit OA-stimulated tumor necrosis factor α (TNF-α secretion, reactive oxygen species generation, and triglyceride (TG accumulation. Further study manifested that MG significantly suppressed OA-activated mitogen-activated protein kinase (MAPK and nuclear factor-kappa B (NF-κB signaling pathways and that these inflammatory responses can be negated by pretreatment with inhibitors of extracellular regulated protein kinase and c-Jun N-terminal kinase (U0126 and SP600125, respectively. In addition, MG dramatically upregulated peroxisome proliferator-activated receptor α (PPARα translocation and reduced sterol regulatory element-binding protein 1c (SREBP-1c protein synthesis and excretion, both of which are dependent upon the phosphorylation of adenosine monophosphate (AMP-activated protein kinase (AMPK, acetyl-CoA carboxylase, and AKT kinase (AKT. However, MG suspended the activation of PPARα expression and was thus blocked by pretreatment with LY294002 and compound c (specific inhibitors of AKT and AMPK. Furthermore, MG clearly alleviated serum TG and total cholesterol release; upregulated AKT, AMPK, and PPARα expression; suppressed SREBP-1c generation; and alleviated hepatic steatosis and dyslipidemia in Ty-induced hyperlipidemia mice. Taken together, these results suggest that MG exerts protective effects against steatosis, hyperlipidemia, and the underlying mechanism, which may be closely associated with AKT/AMPK/PPARα activation and MAPK/NF-κB/SREBP-1c inhibition.

Final report on the safety assessment of AloeAndongensis Extract, Aloe Andongensis Leaf Juice,aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice,aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract.

Science.gov (United States)

2007-01-01

Plant materials derived from the Aloe plant are used as cosmetic ingredients, including Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice, Aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract. These ingredients function primarily as skin-conditioning agents and are included in cosmetics only at low concentrations. The Aloe leaf consists of the pericyclic cells, found just below the plant's skin, and the inner central area of the leaf, i.e., the gel, which is used for cosmetic products. The pericyclic cells produce a bitter, yellow latex containing a number of anthraquinones, phototoxic compounds that are also gastrointestinal irritants responsible for cathartic effects. The gel contains polysaccharides, which can be acetylated, partially acetylated, or not acetylated. An industry established limit for anthraquinones in aloe-derived material for nonmedicinal use is 50 ppm or lower. Aloe-derived ingredients are used in a wide variety of cosmetic product types at concentrations of raw material that are 0.1% or less, although can be as high as 20%. The concentration of Aloe in the raw material also may vary from 100% to a low of 0.0005%. Oral administration of various anthraquinone components results in a rise in their blood concentrations, wide systemic distribution, accumulation in the liver and kidneys, and excretion in urine and feces; polysaccharide components are distributed systemically and metabolized into smaller molecules. aloe-derived material has fungicidal, antimicrobial, and antiviral activities, and has been effective in wound healing and infection treatment in animals. Aloe barbadensis (also known as Aloe vera)-derived ingredients were not toxic

Identification of a novel receptor-like protein kinase that interacts with a geminivirus nuclear shuttle protein

International Nuclear Information System (INIS)

Mariano, Andrea C.; Andrade, Maxuel O.; Santos, Anesia A.; Carolino, Sonia M.B.; Oliveira, Marli L.; Baracat-Pereira, Maria Cristina; Brommonshenkel, Sergio H.; Fontes, Elizabeth P.B.

2004-01-01

Despite extensive studies in plant virus-host interactions, the molecular mechanisms of geminivirus movement and interactions with host components remain largely unknown. A tomato kinase protein and its soybean homolog were found to interact specifically with the nuclear shuttle protein (NSP) of Tomato golden mosaic virus (TGMV) and Tomato crinkle leaf yellows virus (TCrLYV) through yeast two-hybrid screening and in vitro protein binding assays. These proteins, designated LeNIK (Lycopersicon esculentum NSP-Interacting Kinase) and GmNIK (Glycine max NIK), belong to the LRR-RLK (leucine rich-repeat receptor-like kinase) family that is involved in plant developmental processes and/or resistance response. As such, NIK is structurally organized into characteristic domains, including a serine/threonine kinase domain with a nucleotide binding site at the C-terminal region, an internal transmembrane segment and leucine-rich repeats (LRR) at the N-terminal portion. The potential significance of the NSP-NIK interaction is discussed

Biotin augments acetyl CoA carboxylase 2 gene expression in the hypothalamus, leading to the suppression of food intake in mice.

Science.gov (United States)

Sone, Hideyuki; Kamiyama, Shin; Higuchi, Mutsumi; Fujino, Kaho; Kubo, Shizuka; Miyazawa, Masami; Shirato, Saya; Hiroi, Yuka; Shiozawa, Kota

2016-07-29

It is known that biotin prevents the development of diabetes by increasing the functions of pancreatic beta-cells and improving insulin sensitivity in the periphery. However, its anti-obesity effects such as anorectic effects remain to be clarified. Acetyl CoA carboxylase (ACC), a biotin-dependent enzyme, has two isoforms (ACC1 and ACC2) and serves to catalyze the reaction of acetyl CoA to malonyl CoA. In the hypothalamus, ACC2 increases the production of malonyl CoA, which acts as a satiety signal. In this study, we investigated whether biotin increases the gene expression of ACC2 in the hypothalamus and suppresses food intake in mice administered excessive biotin. Food intake was significantly decreased by biotin, but plasma regulators of appetite, including glucose, ghrelin, and leptin, were not affected. On the other hand, biotin notably accumulated in the hypothalamus and enhanced ACC2 gene expression there, but it did not change the gene expression of ACC1, malonyl CoA decarboxylase (a malonyl CoA-degrading enzyme), and AMP-activated protein kinase α-2 (an ACC-inhibitory enzyme). These findings strongly suggest that biotin potentiates the suppression of appetite by upregulating ACC2 gene expression in the hypothalamus. This effect of biotin may contribute to the prevention of diabetes by biotin treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Incorporation of 14CO2 by illuminated intact leaves of bean (PHASEOLUS VULGARIS) plants

International Nuclear Information System (INIS)

Andrade, A.G. de

1980-01-01

Bean plants were grown in hydroponic nutrient solution, maintained in controlled environment. Measurements of the photosynthetic activity using the method of 14 CO 2 incorporation in intact leaves with portable equipment were made on the central leaflet of the first trifoliate leaf except when the effect of leaf age was studied in which case all central leaflets of the same branch were used. The data obtained indicated differences in the photosynthetic efficiency of bean (Phaseolus vulgaris) cultivars. Relative differences in RuDP carboxylase activity in the crude extracts of leaves, leaf area and leaf chlorophyll content were also observed. Rates of 14 CO 2 incorporation at saturating light varied from 14.94 to 22.96 mg CO 2 .dm -2 .h and the 6 studied cultivars could be divided into two classes: Classe 1 (above 20 mg CO 2 .dm -2 .h): Pirata-1, Rosinha G-2, and Pintadinho Precoce; Classe 2 (below 20 mg CO 2 .dm - 2 .h): Carioca, Rosinha Precoce and Pintado. Plants of the same cultivar showed a relatively high variability and a strong dependence in relation to environmental conditions. Differences among cultivars in relation to RuDP carboxylase activity, leaf area and leaf age were correlated to photosynthetic rate. (Author) [pt

Schistosoma mansoni Phosphoenolpyruvate Carboxykinase, a Novel Egg Antigen: Immunological Properties of the Recombinant Protein and Identification of a T-Cell Epitope

OpenAIRE

Asahi, Hiroko; Osman, Ahmed; Cook, Rosemary M.; LoVerde, Philip T.; Stadecker, Miguel J.

2000-01-01

In schistosomiasis mansoni, hepatic granulomatous inflammation surrounding parasite eggs is mediated by CD4+ T helper (Th) cells sensitized to schistosomal egg antigens (SEA). We previously showed that a prominent lymphoproliferative response of CD4+ Th cells from schistosome-infected C57BL/6 (BL/6) mice was directed against a 62-kDa component of SEA. A partial amino acid sequence of the 62-kDa component was found to be identical with one present in the enzyme phosphoenolpyruvate carboxykinas...

Kinetic and Thermodynamic Analysis of Acetyl-CoA Activation of Staphylococcus aureus Pyruvate Carboxylase.

Science.gov (United States)

Westerhold, Lauren E; Bridges, Lance C; Shaikh, Saame Raza; Zeczycki, Tonya N

2017-07-11

Allosteric regulation of pyruvate carboxylase (PC) activity is pivotal to maintaining metabolic homeostasis. In contrast, dysregulated PC activity contributes to the pathogenesis of numerous diseases, rendering PC a possible target for allosteric therapeutic development. Recent research efforts have focused on demarcating the role of acetyl-CoA, one of the most potent activators of PC, in coordinating catalytic events within the multifunctional enzyme. Herein, we report a kinetic and thermodynamic analysis of acetyl-CoA activation of the Staphylococcus aureus PC (SaPC)-catalyzed carboxylation of pyruvate to identify novel means by which acetyl-CoA synchronizes catalytic events within the PC tetramer. Kinetic and linked-function analysis, or thermodynamic linkage analysis, indicates that the substrates of the biotin carboxylase and carboxyl transferase domain are energetically coupled in the presence of acetyl-CoA. In contrast, both kinetic and energetic coupling between the two domains is lost in the absence of acetyl-CoA, suggesting a functional role for acetyl-CoA in facilitating the long-range transmission of substrate-induced conformational changes within the PC tetramer. Interestingly, thermodynamic activation parameters for the SaPC-catalyzed carboxylation of pyruvate are largely independent of acetyl-CoA. Our results also reveal the possibility that global conformational changes give rise to observed species-specific thermodynamic activation parameters. Taken together, our kinetic and thermodynamic results provide a possible allosteric mechanism by which acetyl-CoA coordinates catalysis within the PC tetramer.

The MDM2-p53-pyruvate carboxylase signalling axis couples mitochondrial metabolism to glucose-stimulated insulin secretion in pancreatic β-cells

DEFF Research Database (Denmark)

Li, Xiaomu; Cheng, Kenneth K. Y.; Liu, Zhuohao

2016-01-01

deletion or pharmacological inhibition of its negative regulator MDM2, impairs GSIS, leading to glucose intolerance in mice. Mechanistically, p53 activation represses the expression of the mitochondrial enzyme pyruvate carboxylase (PC), resulting in diminished production of the TCA cycle intermediates...

Maize YABBY genes drooping leaf1 and drooping leaf2 affect agronomic traits by regulating leaf architecture

Science.gov (United States)

Leaf architectural traits, such as length, width and angle, directly influence canopy structure and light penetration, photosynthate production and overall yield. We discovered and characterized a maize (Zea mays) mutant with aberrant leaf architecture we named drooping leaf1 (drl1), as leaf blades ...

Cerebral Gluconeogenesis and Diseases

Science.gov (United States)

Yip, James; Geng, Xiaokun; Shen, Jiamei; Ding, Yuchuan

2017-01-01

The gluconeogenesis pathway, which has been known to normally present in the liver, kidney, intestine, or muscle, has four irreversible steps catalyzed by the enzymes: pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, and glucose 6-phosphatase. Studies have also demonstrated evidence that gluconeogenesis exists in brain astrocytes but no convincing data have yet been found in neurons. Astrocytes exhibit significant 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 activity, a key mechanism for regulating glycolysis and gluconeogenesis. Astrocytes are unique in that they use glycolysis to produce lactate, which is then shuttled into neurons and used as gluconeogenic precursors for reduction. This gluconeogenesis pathway found in astrocytes is becoming more recognized as an important alternative glucose source for neurons, specifically in ischemic stroke and brain tumor. Further studies are needed to discover how the gluconeogenesis pathway is controlled in the brain, which may lead to the development of therapeutic targets to control energy levels and cellular survival in ischemic stroke patients, or inhibit gluconeogenesis in brain tumors to promote malignant cell death and tumor regression. While there are extensive studies on the mechanisms of cerebral glycolysis in ischemic stroke and brain tumors, studies on cerebral gluconeogenesis are limited. Here, we review studies done to date regarding gluconeogenesis to evaluate whether this metabolic pathway is beneficial or detrimental to the brain under these pathological conditions. PMID:28101056

Cerebral Gluconeogenesis and Diseases.

Science.gov (United States)

Yip, James; Geng, Xiaokun; Shen, Jiamei; Ding, Yuchuan

2016-01-01

The gluconeogenesis pathway, which has been known to normally present in the liver, kidney, intestine, or muscle, has four irreversible steps catalyzed by the enzymes: pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase, and glucose 6-phosphatase. Studies have also demonstrated evidence that gluconeogenesis exists in brain astrocytes but no convincing data have yet been found in neurons. Astrocytes exhibit significant 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 activity, a key mechanism for regulating glycolysis and gluconeogenesis. Astrocytes are unique in that they use glycolysis to produce lactate, which is then shuttled into neurons and used as gluconeogenic precursors for reduction. This gluconeogenesis pathway found in astrocytes is becoming more recognized as an important alternative glucose source for neurons, specifically in ischemic stroke and brain tumor. Further studies are needed to discover how the gluconeogenesis pathway is controlled in the brain, which may lead to the development of therapeutic targets to control energy levels and cellular survival in ischemic stroke patients, or inhibit gluconeogenesis in brain tumors to promote malignant cell death and tumor regression. While there are extensive studies on the mechanisms of cerebral glycolysis in ischemic stroke and brain tumors, studies on cerebral gluconeogenesis are limited. Here, we review studies done to date regarding gluconeogenesis to evaluate whether this metabolic pathway is beneficial or detrimental to the brain under these pathological conditions.

Maternal obesity reduces milk lipid production in lactating mice by inhibiting acetyl-CoA carboxylase and impairing fatty acid synthesis.

Science.gov (United States)

Saben, Jessica L; Bales, Elise S; Jackman, Matthew R; Orlicky, David; MacLean, Paul S; McManaman, James L

2014-01-01

Maternal metabolic and nutrient trafficking adaptations to lactation differ among lean and obese mice fed a high fat (HF) diet. Obesity is thought to impair milk lipid production, in part, by decreasing trafficking of dietary and de novo synthesized lipids to the mammary gland. Here, we report that de novo lipogenesis regulatory mechanisms are disrupted in mammary glands of lactating HF-fed obese (HF-Ob) mice. HF feeding decreased the total levels of acetyl-CoA carboxylase-1 (ACC), and this effect was exacerbated in obese mice. The relative levels of phosphorylated (inactive) ACC, were elevated in the epithelium, and decreased in the adipose stroma, of mammary tissue from HF-Ob mice compared to those of HF-fed lean (HF-Ln) mice. Mammary gland levels of AMP-activated protein kinase (AMPK), which catalyzes formation of inactive ACC, were also selectively elevated in mammary glands of HF-Ob relative to HF-Ln dams or to low fat fed dams. These responses correlated with evidence of increased lipid retention in mammary adipose, and decreased lipid levels in mammary epithelial cells, of HF-Ob dams. Collectively, our data suggests that maternal obesity impairs milk lipid production, in part, by disrupting the balance of de novo lipid synthesis in the epithelial and adipose stromal compartments of mammary tissue through processes that appear to be related to increased mammary gland AMPK activity, ACC inhibition, and decreased fatty acid synthesis.

Potassium deficiency affects the carbon-nitrogen balance in cotton leaves.

Science.gov (United States)

Hu, Wei; Coomer, Taylor D; Loka, Dimitra A; Oosterhuis, Derrick M; Zhou, Zhiguo

2017-06-01

Potassium (K) plays important roles in the metabolism of carbon (C) and nitrogen (N), but studies of K deficiency affecting C-N balance are lacking. This study explored the influence of K deficiency on C-N interaction in cotton leaves by conducting a field experiment with cotton cultivar DP0912 under two K rates (K0: 0 kg K 2 O ha -1 and K67: 67 kg K 2 O ha -1 ) and a controlled environment experiment with K-deficient solution (K1: 0 mM K + ) and K-sufficient solution (K2: 6 mM K + ). The results showed that leaf K content, leaf number, leaf area, boll number, reproductive dry weight and total dry weight were significant lower under K deficiency (K0 or K1). Lower total chlorophyll content and Chl a/b ratio, and decreased Pn along with lower Gs and higher Ci were measured under K deficiency, suggesting that the decrease in Pn was resulted from non-stomatal limitation. Leaf glucose, fructose, sucrose and starch contents were higher under K deficiency, because lower sucrose export was detected in phloem. Although leaf nitrate and ammonium contents significantly decreased, free amino acid content was increased by 40-63% under K deficiency, since lower amino acid export was also measured in phloem. K deficiency also induced lower soluble protein content in leaves. Leaf ATP level was significantly increased under K deficiency, indicating ATP utilization was lower, so that less energy was supplied to C and N metabolism. The ratio of soluble sugar to free amino acid and the C/N ratio markedly increased under K deficiency, and one reason was that the phloem export reduced more prominent for sucrose (54.6-78.0%) than amino acid (36.7-85.4%) under K deficiency. In addition, lower phosphoenolpyruvate carboxylase activity limited malate and citrate biosynthesis under K deficiency, causing a decrease of C flux into the amino acids, which was not beneficial for maintaining C-N balance. Sucrose phosphate synthase and nitrate reductase activities were lower under K deficiency

Heavy-atom isotope effects on binding of reactants to lactate dehydrogenase and pyruvate kinase

International Nuclear Information System (INIS)

Gawlita, E.

1993-04-01

18 O and 13 C kinetic isotope effects have been measured on the reaction of pyruvate kinase with phospho-enol-pyruvate and ADP using a remote label technique. The magnitude of both investigated isotope effects showed a dependence on the concentration of ADP. However, while the carbon effect was simply 'washed out' to unity at high ATP concentration, the oxygen effect becomes inverse and reached 0.9928 at the highest used concentration of ADP. Such a result testifies that the assumption of the negligible effect of isotopic substitution on enzyme-substrate associations remains correct only for carbon effects. An equilibrium 18 O isotope effect on association of oxalate with lactate dehydrogenase in the presence of NADHP has been evaluated by both experimental and theoretical means. Experimental methods, which involved equilibrium dialysis and gas chromatographic/mass spectrometric measurement of isotopic ration, yielded an inverse value of 0.9840. Semiempirical methods involved vibrational analysis of oxalate in two different environments. The comparison of calculated values with the experimentally determined isotope effect indicated that the AM 1 Hamiltonian proved superior to its PM 3 counterpart in this modelling. 160 refs, 8 figs, 18 tabs

Differences in the Sensitivity to UVB Radiation of Two Cultivars of Rice (Oryza sativa L.)

OpenAIRE

Jun, Hidema; Hye-Sook, Kang; Tadashi, Kumagai; Institute of Genetic Ecology, Tohoku University; Institute of Genetic Ecology, Tohoku University; Institute of Genetic Ecology, Tohoku University

1996-01-01

The effects of UVB radiation on the growth of two cultivars of Japanese lowland rice (Oryza sativa L.), Sasanishiki and Norin 1, were examined in a phytotron. Supplementation of visible radiation with UVB radiation reduced plant length, tiller number, the fresh and dry weights of the aboveground parts of plants, and the amounts of total leaf nitrogen, chlorophyll, soluble protein and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) in the eighth leaf, the youngest fully expanded leaf...

Exercise-induced regulation of key factors in substrate choice and gluconeogenesis in mouse liver

DEFF Research Database (Denmark)

Knudsen, Jakob Grunnet; Biensø, Rasmus Sjørup; Hassing, Helle Adser

2015-01-01

As the demand for hepatic glucose production increases during exercise, regulation of liver substrate choice and gluconeogenic activity becomes essential. The aim of the present study was to investigate the effect of a single exercise bout on gluconeogenic protein content and regulation of enzymes...... involved in substrate utilization in the liver. Mice were subjected to 1 h of treadmill exercise, and livers were removed immediately, 4 or 10 h after exercise. Glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxylase (PEPCK) mRNA contents in the liver increased immediately after exercise, while...... phosphorylation decreased immediately after exercise may indicate that carbohydrates rather than fatty acids are utilized for oxidation in the liver during non-exhaustive exercise....

"Breath figures" on leaf surfaces-formation and effects of microscopic leaf wetness.

Science.gov (United States)

Burkhardt, Juergen; Hunsche, Mauricio

2013-01-01

"Microscopic leaf wetness" means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

Protoplast isolation, transient transformation of leaf mesophyll protoplasts and improved Agrobacterium-mediated leaf disc infiltration of Phaseolus vulgaris: tools for rapid gene expression analysis.

Science.gov (United States)

Nanjareddy, Kalpana; Arthikala, Manoj-Kumar; Blanco, Lourdes; Arellano, Elizabeth S; Lara, Miguel

2016-06-24

Phaseolus vulgaris is one of the most extensively studied model legumes in the world. The P. vulgaris genome sequence is available; therefore, the need for an efficient and rapid transformation system is more imperative than ever. The functional characterization of P. vulgaris genes is impeded chiefly due to the non-amenable nature of Phaseolus sp. to stable genetic transformation. Transient transformation systems are convenient and versatile alternatives for rapid gene functional characterization studies. Hence, the present work focuses on standardizing methodologies for protoplast isolation from multiple tissues and transient transformation protocols for rapid gene expression analysis in the recalcitrant grain legume P. vulgaris. Herein, we provide methodologies for the high-throughput isolation of leaf mesophyll-, flower petal-, hypocotyl-, root- and nodule-derived protoplasts from P. vulgaris. The highly efficient polyethylene glycol-mannitol magnesium (PEG-MMG)-mediated transformation of leaf mesophyll protoplasts was optimized using a GUS reporter gene. We used the P. vulgaris SNF1-related protein kinase 1 (PvSnRK1) gene as proof of concept to demonstrate rapid gene functional analysis. An RT-qPCR analysis of protoplasts that had been transformed with PvSnRK1-RNAi and PvSnRK1-OE vectors showed the significant downregulation and ectopic constitutive expression (overexpression), respectively, of the PvSnRK1 transcript. We also demonstrated an improved transient transformation approach, sonication-assisted Agrobacterium-mediated transformation (SAAT), for the leaf disc infiltration of P. vulgaris. Interestingly, this method resulted in a 90 % transformation efficiency and transformed 60-85 % of the cells in a given area of the leaf surface. The constitutive expression of YFP further confirmed the amenability of the system to gene functional characterization studies. We present simple and efficient methodologies for protoplast isolation from multiple P

Effect of Plant Growth Regulators on Leaf Number, Leaf Area and Leaf Dry Matter in Grape

Directory of Open Access Journals (Sweden)

Zahoor Ahmad BHAT

2011-03-01

Full Text Available Influence of phenylureas (CPPU and brassinosteriod (BR along with GA (gibberellic acid were studied on seedless grape vegetative characteristics like leaf number, leaf area and leaf dry matter. Growth regulators were sprayed on the vines either once (7 days after fruit set or 15 days after fruit set or twice (7+15 days after fruit set. CPPU 2 ppm+BR 0.4 ppm+GA 25 ppm produced maximum number of leaves (18.78 while as untreated vines produced least leaf number (16.22 per shoot. Maximum leaf area (129.70 cm2 and dry matter content (26.51% was obtained with higher CPPU (3 ppm and BR (0.4 ppm combination along with GA 25 ppm. Plant growth regulators whether naturally derived or synthetic are used to improve the productivity and quality of grapes. The relatively high value of grapes justifies more expensive inputs. A relatively small improvement in yield or fruit quality can justify the field application of a very costly product. Application of new generation growth regulators like brassinosteroids and phenylureas like CPPU have been reported to increase the leaf number as well as leaf area and dry matter thereby indirectly influencing the fruit yield and quality in grapes.

Measurement of 2-carboxyarabinitol 1-phosphate in plant leaves by isotope dilution

International Nuclear Information System (INIS)

Moore, B.D.; Kobza, J.; Seemann, J.R.

1991-01-01

The level of 2-carboxyarabinitol 1-phosphate (CA1P) in leaves of 12 species was determined by an isotope dilution assay. 14 C-labeled standard was synthesized from [2- 14 C]carboxyarabinitol 1,5-bisphosphate using acid phosphatase, and was added at the initial point of leaf extraction. Leaf CA1P was purified and its specific activity determined. CA1P was found in dark-treated leaves of all species examined, including spinach (Spinacea oleracea), wheat (Triticum aestivum), Arabidopsis thaliana, and maize (Zea mays). The highest amounts were found in bean (Phaseolus vulgaris) and petunia (Petunia hybrida), which had 1.5 to 1.8 moles CA1P per mole ribulose 1,5-bisphosphate carboxylase catalytic sites. Most species had intermediate amounts of CA1P (0.2 to 0.8 mole CA1P per mole catalytic sites). Such intermediate to high levels of CA1P support the hypothesis that CA1P functions in many species as a light-dependent regulator of ribulose 1,5-bisphosphate carboxylase activity and whole leaf photosynthetic CO 2 assimilation. However, CA1P levels in spinach, wheat, and A. thaliana were particularly low (less than 0.09 mole CA1P per mole catalytic sites). In such species, CA1P does not likely have a significant role in regulating ribulose 1,5-bisphosphate carboxylase activity, but could have a different physiological role

Mesophyll conductance in Zea mays responds transiently to CO2 availability: implications for transpiration efficiency in C4 crops.

Science.gov (United States)

Kolbe, Allison R; Cousins, Asaph B

2018-03-01

Mesophyll conductance (g m ) describes the movement of CO 2 from the intercellular air spaces below the stomata to the site of initial carboxylation in the mesophyll. In contrast with C 3 -g m , little is currently known about the intraspecific variation in C 4 -g m or its responsiveness to environmental stimuli. To address these questions, g m was measured on five maize (Zea mays) lines in response to CO 2 , employing three different estimates of g m . Each of the methods indicated a significant response of g m to CO 2 . Estimates of g m were similar between methods at ambient and higher CO 2 , but diverged significantly at low partial pressures of CO 2 . These differences are probably driven by incomplete chemical and isotopic equilibrium between CO 2 and bicarbonate under these conditions. Carbonic anhydrase and phosphoenolpyruvate carboxylase in vitro activity varied significantly despite similar values of g m and leaf anatomical traits. These results provide strong support for a CO 2 response of g m in Z. mays, and indicate that g m in maize is probably driven by anatomical constraints rather than by biochemical limitations. The CO 2 response of g m indicates a potential role for facilitated diffusion in C 4 -g m . These results also suggest that water-use efficiency could be enhanced in C 4 species by targeting g m . © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Green tissue-specific co-expression of chitinase and oxalate oxidase 4 genes in rice for enhanced resistance against sheath blight.

Science.gov (United States)

Karmakar, Subhasis; Molla, Kutubuddin Ali; Chanda, Palas K; Sarkar, Sailendra Nath; Datta, Swapan K; Datta, Karabi

2016-01-01

Green tissue-specific simultaneous overexpression of two defense-related genes ( OsCHI11 & OsOXO4 ) in rice leads to significant resistance against sheath blight pathogen ( R. solani ) without distressing any agronomically important traits. Overexpressing two defense-related genes (OsOXO4 and OsCHI11) cloned from rice is effective at enhancing resistance against sheath blight caused by Rhizoctonia solani. These genes were expressed under the control of two different green tissue-specific promoters, viz. maize phosphoenolpyruvate carboxylase gene promoter, PEPC, and rice cis-acting 544-bp DNA element, immediately upstream of the D54O translational start site, P D54O-544 . Putative T0 transgenic rice plants were screened by PCR and integration of genes was confirmed by Southern hybridization of progeny (T1) rice plants. Successful expression of OsOXO4 and OsCHI11 in all tested plants was confirmed. Expression of PR genes increased significantly following pathogen infection in overexpressing transgenic plants. Following infection, transgenic plants exhibited elevated hydrogen peroxide levels, significant changes in activity of ROS scavenging enzymes and reduced membrane damage when compared to their wild-type counterpart. In a Rhizoctonia solani toxin assay, a detached leaf inoculation test and an in vivo plant bioassay, transgenic plants showed a significant reduction in disease symptoms in comparison to non-transgenic control plants. This is the first report of overexpression of two different PR genes driven by two green tissue-specific promoters providing enhanced sheath blight resistance in transgenic rice.

Ammonium intensifies CAM photosynthesis and counteracts drought effects by increasing malate transport and antioxidant capacity in Guzmania monostachia.

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Pereira, Paula Natália; Gaspar, Marília; Smith, J Andrew C; Mercier, Helenice

2018-04-09

Guzmania monostachia (Bromeliaceae) is a tropical epiphyte capable of up-regulating crassulacean acid metabolism (CAM) in its photosynthetic tissues in response to changing nutrient and water availability. Previous studies have shown that under drought there is a gradient of increasing CAM expression from the basal (youngest) to the apical (oldest) portion of the leaves, and additionally that nitrogen deficiency can further increase CAM intensity in the leaf apex of this bromeliad. The present study investigated the inter-relationships between nitrogen source (nitrate and/or ammonium) and water deficit in regulating CAM expression in G. monostachia leaves. The highest CAM activity was observed under ammonium nutrition in combination with water deficit. This was associated with enhanced activity of the key enzyme phosphoenolpyruvate carboxylase, elevated rates of ATP- and PPi-dependent proton transport at the vacuolar membrane in the presence of malate, and increased transcript levels of the vacuolar malate channel-encoding gene, ALMT. Water deficit was consistently associated with higher levels of total soluble sugars, which were maximal under ammonium nutrition, as were the activities of several antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase). Thus, ammonium nutrition, whilst associated with the highest degree of CAM induction in G. monostachia, also mitigates the effects of water deficit by osmotic adjustment and can limit oxidative damage in the leaves of this bromeliad under conditions that may be typical of its epiphytic habitat.

Domain interaction in rabbit muscle pyruvate kinase. II. Small angle neutron scattering and computer simulation.

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Consler, T G; Uberbacher, E C; Bunick, G J; Liebman, M N; Lee, J C

1988-02-25

The effects of ligands on the structure of rabbit muscle pyruvate kinase were studied by small angle neutron scattering. The radius of gyration, RG, decreases by about 1 A in the presence of the substrate phosphoenolpyruvate, but increases by about the same magnitude in the presence of the allosteric inhibitor phenylalanine. With increasing pH or in the absence of Mg2+ and K+, the RG of pyruvate kinase increases. Hence, there is a 2-A difference in RG between two alternative conformations. Length distribution analysis indicates that, under all experimental conditions which increase the radius of gyration, there is a pronounced increase observed in the probability for interatomic distance between 80 and 110 A. These small angle neutron scattering results indicate a "contraction" and "expansion" of the enzyme when it transforms between its active and inactive forms. Using the alpha-carbon coordinates of crystalline cat muscle pyruvate kinase, a length distribution profile was calculated, and it matches the scattering profile of the inactive form. These observations are expected since the crystals were grown in the absence of divalent cations (Stuart, D. I., Levine, M., Muirhead, H., and Stammers, D. K. (1979) J. Mol. Biol. 134, 109-142). Hence, results from neutron scattering, x-ray crystallographic, and sedimentation studies (Oberfelder, R. W., Lee, L. L.-Y., and Lee, J.C. (1984) Biochemistry 23, 3813-3821) are totally consistent with each other. With the aid of computer modeling, the crystal structure has been manipulated in order to effect changes that are consistent with the conformational change described by the solution scattering data. The structural manipulation involves the rotation of the B domain relative to the A domain, leading to the closure of the cleft between these domains. These manipulations resulted in the generation of new sets of atomic (C-alpha) coordinates, which were utilized in calculations, the result of which compared favorably with the

Phosphorylation of the Yeast Choline Kinase by Protein Kinase C

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Choi, Mal-Gi; Kurnov, Vladlen; Kersting, Michael C.; Sreenivas, Avula; Carman, George M.

2005-01-01

The Saccharomyces cerevisiae CKI1-encoded choline kinase catalyzes the committed step in phosphatidylcholine synthesis via the Kennedy pathway. The enzyme is phosphorylated on multiple serine residues, and some of this phosphorylation is mediated by protein kinase A. In this work, we examined the hypothesis that choline kinase is also phosphorylated by protein kinase C. Using choline kinase as a substrate, protein kinase C activity was dose- and time-dependent, and dependent on the concentrations of choline kinase (Km = 27 μg/ml) and ATP (Km = 15 μM). This phosphorylation, which occurred on a serine residue, was accompanied by a 1.6-fold stimulation of choline kinase activity. The synthetic peptide SRSSS25QRRHS (Vmax/Km = 17.5 mM-1 μmol min-1 mg-1) that contains the protein kinase C motif for Ser25 was a substrate for protein kinase C. A Ser25 to Ala (S25A) mutation in choline kinase resulted in a 60% decrease in protein kinase C phosphorylation of the enzyme. Phosphopeptide mapping analysis of the S25A mutant enzyme confirmed that Ser25 was a protein kinase C target site. In vivo, the S25A mutation correlated with a decrease (55%) in phosphatidylcholine synthesis via the Kennedy pathway whereas an S25D phosphorylation site mimic correlated with an increase (44%) in phosphatidylcholine synthesis. Whereas the S25A (protein kinase C site) mutation did not affect the phosphorylation of choline kinase by protein kinase A, the S30A (protein kinase A site) mutation caused a 46% reduction in enzyme phosphorylation by protein kinase C. A choline kinase synthetic peptide (SQRRHS30LTRQ) containing Ser30 was a substrate (Vmax/Km = 3.0 mM−1 μmol min−1 mg−1) for protein kinase C. Comparison of phosphopeptide maps of the wild type and S30A mutant choline kinase enzymes phosphorylated by protein kinase C confirmed that Ser30 was also a target site for protein kinase C. PMID:15919656

A chemical genetic approach to engineer phototropin kinases for substrate labeling.

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Schnabel, Jonathan; Hombach, Peter; Waksman, Thomas; Giuriani, Giovanni; Petersen, Jan; Christie, John M

2018-04-13

Protein kinases (PKs) control many aspects of plant physiology by regulating signaling networks through protein phosphorylation. Phototropins (phots) are plasma membrane-associated serine/threonine PKs that control a range of physiological processes that collectively serve to optimize photosynthetic efficiency in plants. These include phototropism, leaf positioning and flattening, chloroplast movement, and stomatal opening. Despite their identification over two decades ago, only a handful of substrates have been identified for these PKs. Progress in this area has been hampered by the lack of a convenient means to confirm the identity of potential substrate candidates. Here we demonstrate that the kinase domain of Arabidopsis phot1 and phot2 can be successfully engineered to accommodate non-natural ATP analogues by substituting the bulky gatekeeper residue threonine for glycine. This approach circumvents the need for radioactivity to track phot kinase activity and follow light-induced receptor autophosphorylation in vitro by incorporating thiophosphate from N 6 -benzyl-ATPγS. Consequently, thiophosphorylation of phot substrate candidates can be readily monitored when added or co-expressed with phots in vitro Furthermore, gatekeeper-modified phot1 retained its functionality and its ability to accommodate N 6 -benzyl-ATPγS as a phosphodonor when expressed in Arabidopsis We therefore anticipate that this chemical genetic approach will provide new opportunities for labeling and identifying substrates for phots and other related AGC kinases under in vitro and near-native in vivo conditions. © 2018 Schnabel et al.

Evidence against translational repression by the carboxyltransferase component of Escherichia coli acetyl coenzyme A carboxylase.

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Smith, Alexander C; Cronan, John E

2014-11-01

In Escherichia coli, synthesis of the malonyl coenzyme A (malonyl-CoA) required for membrane lipid synthesis is catalyzed by acetyl-CoA carboxylase, a large complex composed of four subunits. The subunit proteins are needed in a defined stoichiometry, and it remains unclear how such production is achieved since the proteins are encoded at three different loci. Meades and coworkers (G. Meades, Jr., B. K. Benson, A. Grove, and G. L. Waldrop, Nucleic Acids Res. 38:1217-1227, 2010, doi:http://dx.doi.org/10.1093/nar/gkp1079) reported that coordinated production of the AccA and AccD subunits is due to a translational repression mechanism exerted by the proteins themselves. The AccA and AccD subunits form the carboxyltransferase (CT) heterotetramer that catalyzes the second partial reaction of acetyl-CoA carboxylase. Meades et al. reported that CT tetramers bind the central portions of the accA and accD mRNAs and block their translation in vitro. However, long mRNA molecules (500 to 600 bases) were required for CT binding, but such long mRNA molecules devoid of ribosomes seemed unlikely to exist in vivo. This, plus problematical aspects of the data reported by Meades and coworkers, led us to perform in vivo experiments to test CT tetramer-mediated translational repression of the accA and accD mRNAs. We report that increased levels of CT tetramer have no detectable effect on translation of the CT subunit mRNAs. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Why do leaf-tying caterpillars abandon their leaf ties?

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Michelle Sliwinski

2013-09-01

Full Text Available Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats, but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm2 leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently

Phosphoenolpyruvate phosphotransferase system components positively regulate Klebsiella biofilm formation

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Yu-Tze Horng

2018-04-01

Full Text Available Background/Purpose: Klebsiella pneumoniae is one of the leading causes of device-related infections (DRIs, which are associated with attachment of bacteria to these devices to form a biofilm. The latter is composed of not only bacteria but also extracellular polymeric substances (EPSes consisting of extracellular DNAs, polysaccharides, and other macromolecules. The phosphoenolpyruvate (PEP:carbohydrate phosphotransferase system (PTS regulates diverse processes of bacterial physiology. In the genome of K. pneumoniae MGH 78578, we found an uncharacterized enzyme II complex homolog of PTS: KPN00353 (EIIA homolog, KPN00352 (EIIB homolog, and KPN00351 (EIIC homolog. The aim of this study was to characterize the potential physiological role of KPN00353, KPN00352, and KPN00351 in biofilm formation by K. pneumoniae. Methods/Results: We constructed the PTS mutants and recombinant strains carrying the gene(s of PTS. The recombinant K. pneumoniae strain overexpressing KPN00353–KPN00352–KPN00351 produced more extracellular matrix than did the vector control according to transmission and scanning electron microscopy. Judging by quantification of biofilm formation, of extracellular DNA (eDNA, and of capsular polysaccharide, the recombinant strain overexpressing KPN00353-KPN00352-KPN00351 produced more biofilm and capsular polysaccharide after overnight culture and more eDNA in the log phase as compared to the vector control. Conclusion: The genes, KPN00353–KPN00352–KPN00351, encode a putative enzyme II complex in PTS and positively regulate biofilm formation by enhancing production of eDNA and capsular polysaccharide in K. pneumoniae. Five proteins related to chaperones, to the citric acid cycle, and to quorum sensing are upregulated by the KPN00353–KPN00352–KPN00351 system. Keywords: Klebsiella, PTS, Biofilm, eDNA, Polysaccharide

The antisense expression of AhPEPC1 increases seed oil production in peanuts (Arachis hypogaea L.)

Energy Technology Data Exchange (ETDEWEB)

Pan, L.; Zhang, J.; Chi, X.; Chen, N.; Chen, M.; Wang, M.; Wang, T.; Yang, Z.; Zhang, Z.; Wan, Y.; Yu, S.; Liu, F.

2016-07-01

Although phosphoenolpyruvate carboxylases (PEPCs) are reported to be involved in fatty acid accumulation, nitrogen assimilation, and salt and drought stresses, knowledge regarding PEPC gene functions is still limited, particularly in peanuts (Arachis hypogaea L.). In this study, the antisense expression of the peanut PEPC isoform 1 (AhPEPC1) gene increased the lipid content by 5.7%–10.3%. This indicated that AhPEPC1 might be related to plant lipid accumulation. The transgenic plants underwent more root elongation than the wild-type under salinity stress. Additionally, the specific down regulation of the AhPEPC1 gene improved the salt tolerance in peanuts. This is the first report on the role of PEPC in lipid accumulation and salt tolerance in peanuts.

Salinity and Salicylic Acid Interactions in Affecting Nitrogen Assimilation, Enzyme Activity, Ions Content and Translocation Rate of Maize Plants

International Nuclear Information System (INIS)

Khodary, S.E.A.; Moussa, H.R.

2002-01-01

This study was carried out to establish the relationship between nitrogen metabolism, enzyme activity, ions concentration as well as the translocation rate (TR) of carbohydrates and salicylic acid (SA) in salt-stressed maize (Zea mays L). Salicylic acid plus salinity treatment highly significantly increased: nucleic acids (DNA and RNA), protein content, phosphoenolpyruvate carboxylase (PEPCase) and nitrate reductase (NR) and inhibited nucleases (DNase and RNase) activities compared with Na CI-treated plants. In addition, the ionic levels of potassium (K), phosphorus (P), nitrate (NO 3 ) and the translocation rate of the labelled photo assimilates have also been stimulated while sodium (Na) ions content was decreased. It is concluded that, salinazid maize plants might show an enhancement in their growth pattern upon salicylic acid application

Phytochrome-mediated responses of cells and protoplasts of green calli obtained from the leaves of a CAM plant.

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Mricha, A; Brulfert, J; Pierre, J N; Queiroz, O

1990-04-01

Green callus obtained from leaves of the CAM-inducible plant Kalanchoe blossfeldiana cv. Montezuma has previously been shown to perform C3-type photosynthesis under 16-h days and to shift to crassulacean acid metabolism (CAM) under 9-h days. The utilization of photoperiodic regimes (i.e. night interruptions by 30 min red light) established that CAM induction in the callus was under the control of phytochrome, as shown by measurements of CAM criteria: phosphoenolpyruvate carboxylase activity and malic acid pools. Short-term responsiveness of the callus cells to phytochrome modulations by monochromatic radiations was also established by the rapid changes observed in the diameter of the callus-derived protoplasts. These results provide further evidence that whole plant correlations are not necessary for phytochrome operativity.

Unraveling the evolutionary history of the phosphoryl-transfer chain of the phosphoenolpyruvate:phosphotransferase system through phylogenetic analyses and genome context

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Zúñiga Manuel

2008-05-01

Full Text Available Abstract Background The phosphoenolpyruvate phosphotransferase system (PTS plays a major role in sugar transport and in the regulation of essential physiological processes in many bacteria. The PTS couples solute transport to its phosphorylation at the expense of phosphoenolpyruvate (PEP and it consists of general cytoplasmic phosphoryl transfer proteins and specific enzyme II complexes which catalyze the uptake and phosphorylation of solutes. Previous studies have suggested that the evolution of the constituents of the enzyme II complexes has been driven largely by horizontal gene transfer whereas vertical inheritance has been prevalent in the general phosphoryl transfer proteins in some bacterial groups. The aim of this work is to test this hypothesis by studying the evolution of the phosphoryl transfer proteins of the PTS. Results We have analyzed the evolutionary history of the PTS phosphoryl transfer chain (PTS-ptc components in 222 complete genomes by combining phylogenetic methods and analysis of genomic context. Phylogenetic analyses alone were not conclusive for the deepest nodes but when complemented with analyses of genomic context and functional information, the main evolutionary trends of this system could be depicted. Conclusion The PTS-ptc evolved in bacteria after the divergence of early lineages such as Aquificales, Thermotogales and Thermus/Deinococcus. The subsequent evolutionary history of the PTS-ptc varied in different bacterial lineages: vertical inheritance and lineage-specific gene losses mainly explain the current situation in Actinobacteria and Firmicutes whereas horizontal gene transfer (HGT also played a major role in Proteobacteria. Most remarkably, we have identified a HGT event from Firmicutes or Fusobacteria to the last common ancestor of the Enterobacteriaceae, Pasteurellaceae, Shewanellaceae and Vibrionaceae. This transfer led to extensive changes in the metabolic and regulatory networks of these bacteria

Can Leaf Spectroscopy Predict Leaf and Forest Traits Along a Peruvian Tropical Forest Elevation Gradient?

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Doughty, Christopher E.; Santos-Andrade, P. E.; Goldsmith, G. R.; Blonder, B.; Shenkin, A.; Bentley, L. P.; Chavana-Bryant, C.; Huaraca-Huasco, W.; Díaz, S.; Salinas, N.; Enquist, B. J.; Martin, R.; Asner, G. P.; Malhi, Y.

2017-11-01

High-resolution spectroscopy can be used to measure leaf chemical and structural traits. Such leaf traits are often highly correlated to other traits, such as photosynthesis, through the leaf economics spectrum. We measured VNIR (visible-near infrared) leaf reflectance (400-1,075 nm) of sunlit and shaded leaves in 150 dominant species across ten, 1 ha plots along a 3,300 m elevation gradient in Peru (on 4,284 individual leaves). We used partial least squares (PLS) regression to compare leaf reflectance to chemical traits, such as nitrogen and phosphorus, structural traits, including leaf mass per area (LMA), branch wood density and leaf venation, and "higher-level" traits such as leaf photosynthetic capacity, leaf water repellency, and woody growth rates. Empirical models using leaf reflectance predicted leaf N and LMA (r2 > 30% and %RMSE < 30%), weakly predicted leaf venation, photosynthesis, and branch density (r2 between 10 and 35% and %RMSE between 10% and 65%), and did not predict leaf water repellency or woody growth rates (r2<5%). Prediction of higher-level traits such as photosynthesis and branch density is likely due to these traits correlations with LMA, a trait readily predicted with leaf spectroscopy.

Leaf size and leaf display of thirty-eight tropical tree species

NARCIS (Netherlands)

Poorter, L.; Rozendaal, D.M.A.

2008-01-01

Trees forage for light through optimal leaf display. Effective leaf display is determined by metamer traits (i.e., the internode, petiole, and corresponding leaf), and thus these traits strongly co-determine carbon gain and as a result competitive advantage in a light-limited environment. We

Role of AMP-activated protein kinase in mechanism of metformin action.

Science.gov (United States)

Zhou, G; Myers, R; Li, Y; Chen, Y; Shen, X; Fenyk-Melody, J; Wu, M; Ventre, J; Doebber, T; Fujii, N; Musi, N; Hirshman, M F; Goodyear, L J; Moller, D E

2001-10-01

Metformin is a widely used drug for treatment of type 2 diabetes with no defined cellular mechanism of action. Its glucose-lowering effect results from decreased hepatic glucose production and increased glucose utilization. Metformin's beneficial effects on circulating lipids have been linked to reduced fatty liver. AMP-activated protein kinase (AMPK) is a major cellular regulator of lipid and glucose metabolism. Here we report that metformin activates AMPK in hepatocytes; as a result, acetyl-CoA carboxylase (ACC) activity is reduced, fatty acid oxidation is induced, and expression of lipogenic enzymes is suppressed. Activation of AMPK by metformin or an adenosine analogue suppresses expression of SREBP-1, a key lipogenic transcription factor. In metformin-treated rats, hepatic expression of SREBP-1 (and other lipogenic) mRNAs and protein is reduced; activity of the AMPK target, ACC, is also reduced. Using a novel AMPK inhibitor, we find that AMPK activation is required for metformin's inhibitory effect on glucose production by hepatocytes. In isolated rat skeletal muscles, metformin stimulates glucose uptake coincident with AMPK activation. Activation of AMPK provides a unified explanation for the pleiotropic beneficial effects of this drug; these results also suggest that alternative means of modulating AMPK should be useful for the treatment of metabolic disorders.

Breast Cancer-Derived Lung Metastases Show Increased Pyruvate Carboxylase-Dependent Anaplerosis

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Stefan Christen

2016-10-01

Full Text Available Cellular proliferation depends on refilling the tricarboxylic acid (TCA cycle to support biomass production (anaplerosis. The two major anaplerotic pathways in cells are pyruvate conversion to oxaloacetate via pyruvate carboxylase (PC and glutamine conversion to α-ketoglutarate. Cancers often show an organ-specific reliance on either pathway. However, it remains unknown whether they adapt their mode of anaplerosis when metastasizing to a distant organ. We measured PC-dependent anaplerosis in breast-cancer-derived lung metastases compared to their primary cancers using in vivo 13C tracer analysis. We discovered that lung metastases have higher PC-dependent anaplerosis compared to primary breast cancers. Based on in vitro analysis and a mathematical model for the determination of compartment-specific metabolite concentrations, we found that mitochondrial pyruvate concentrations can promote PC-dependent anaplerosis via enzyme kinetics. In conclusion, we show that breast cancer cells proliferating as lung metastases activate PC-dependent anaplerosis in response to the lung microenvironment.

3-Methylcrotonyl-coenzyme A carboxylase deficiency in Amish/Mennonite adults identified by detection of increased acylcarnitines in blood spots of their children.

Science.gov (United States)

Gibson, K M; Bennett, M J; Naylor, E W; Morton, D H

1998-03-01

Isolated 3-methylcrotonyl coenzyme A carboxylase (MCC) deficiency was documented in four adult women from the Amish/Mennonite population of Lancaster County, Pennsylvania. Metabolic and enzymatic investigations in these individuals were instituted after the detection of abnormal acylcarnitine profiles in blood spots obtained from their newborn children, in whom MCC activity was normal.

Evaluation of Methane from Sisal Leaf Residue and Palash Leaf Litter

Science.gov (United States)

Arisutha, S.; Baredar, P.; Deshpande, D. M.; Suresh, S.

2014-12-01

The aim of this study is to evaluate methane production from sisal leaf residue and palash leaf litter mixed with different bulky materials such as vegetable market waste, hostel kitchen waste and digested biogas slurry in a laboratory scale anaerobic reactor. The mixture was prepared with 1:1 proportion. Maximum methane content of 320 ml/day was observed in the case of sisal leaf residue mixed with vegetable market waste as the feed. Methane content was minimum (47 ml/day), when palash leaf litter was used as feed. This was due to the increased content of lignin and polyphenol in the feedstock which were of complex structure and did not get degraded directly by microorganisms. Sisal leaf residue mixtures also showed highest content of volatile fatty acids (VFAs) as compared to palash leaf litter mixtures. It was observed that VFA concentration in the digester first increased, reached maximum (when pH was minimum) and then decreased.

‘Breath figures’ on leaf surfaces – formation and effects of microscopic leaf wetness

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Jürgen eBurkhardt

2013-10-01

Full Text Available ‘Microscopic leaf wetness’ means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 µm, microscopic leaf wetness it is about 2 orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the amount and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g. ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

Redox regulation of the AMP-activated protein kinase.

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Yingying Han

2010-11-01

Full Text Available Redox state is a critical determinant of cell function, and any major imbalances can cause severe damage or death.The aim of this study is to determine if AMP-activated protein kinase (AMPK, a cellular energy sensor, is activated by oxidants generated by Berberine in endothelial cells (EC.Bovine aortic endothelial cells (BAEC were exposed to Berberine. AMPK activity and reactive oxygen species were monitored after the incubation.In BAEC, Berberine caused a dose- and time-dependent increase in the phosphorylation of AMPK at Thr172 and acetyl CoA carboxylase (ACC at Ser79, a well characterized downstream target of AMPK. Concomitantly, Berberine increased peroxynitrite, a potent oxidant formed by simultaneous generation of superoxide and nitric oxide. Pre-incubation of BAEC with anti-oxidants markedly attenuated Berberine-enhanced phosphorylation of both AMPK and ACC. Consistently, adenoviral expression of superoxide dismutase and pretreatment of L-N(G-Nitroarginine methyl ester (L-NAME; a non-selective NOS inhibitor blunted Berberine-induced phosphorylation of AMPK. Furthermore, mitochondria-targeted tempol (mito-tempol pretreatment or expression of uncoupling protein attenuated AMPK activation caused by Berberine. Depletion of mitochondria abolished the effects of Berberine on AMPK in EC. Finally, Berberine significantly increased the phosphorylation of LKB1 at Ser307 and gene silencing of LKB1 attenuated Berberine-enhanced AMPK Thr172 phosphorylation in BAEC.Our results suggest that mitochondria-derived superoxide anions and peroxynitrite are required for Berberine-induced AMPK activation in endothelial cells.

Dark CO2 fixation in leaves of tomato plants grown with ammonium and nitrate at nitrogen sources

International Nuclear Information System (INIS)

Ikeda, M.; Yamada, Y.

1981-01-01

The dark (non-photosynthetic) CO 2 fixation was studied in the leaves of ammonium-fed and nitrate-fed tomato plants. The ability to fix 14 CO 2 in the dark of ammonium-fed plants was remarkably lower as compared with nitrate-fed plants, supporting the previous finding that the synthesis of C 4 -compounds from C 3 -compounds was reduced in the leaves of ammonium-fed plants. There was no difference in the activity of PEP carboxylase in extracts prepared from the leaves between both the plants during an early period of the treatment. However, the enzyme activity began to decrease rapidly in ammonium-fed plants 4 days after the treatment. By long-term treatments, the enzyme activity in ammonium-fed plants became half as high as that of nitrate-fed plants. The decreased PEP carboxylase activity in ammonium-fed plants was not associated with the presence of NH 4 -N and the absence of NO 3 -N in the leaf extract, and was not restored by the addition of the leaf extract from nitrate-fed plants. It is concluded that the decreased rate of synthesis of C 4 -compounds from C 3 -compounds in ammonium-fed plants is closely associated with a decrease in the dark fixation involving PEP carboxylase. (orig.)

Comparative Effects of Phosphoenolpyruvate, a Glycolytic Intermediate, as an Organ Preservation Agent with Glucose and N-Acetylcysteine against Organ Damage during Cold Storage of Mouse Liver and Kidney

OpenAIRE

Ishitsuka, Yoichi; Fukumoto, Yusuke; Kondo, Yuki; Irikura, Mitsuru; Kadowaki, Daisuke; Narita, Yuki; Hirata, Sumio; Moriuchi, Hiroshi; Maruyama, Toru; Hamasaki, Naotaka; Irie, Tetsumi

2013-01-01

We evaluated the usefulness of phosphoenolpyruvate (PEP), a glycolytic intermediate with antioxidative and energy supplementation potentials, as an organ preservation agent. Using ex vivo mouse liver and kidney of a static cold storage model, we compared the effects of PEP against organ damage and oxidative stress during cold preservation with those of glucose or N-acetylcysteine (NAC). Lactate dehydrogenase (LDH) leakage, histological changes, and oxidative stress parameters (measured as thi...

Photoperiodism and enzyme rhythms: Kinetic characteristics of the photoperiodic induction of Crassulacean acid metabolism.

Science.gov (United States)

Brulfert, J; Guerrier, D; Queiroz, O

1975-01-01

The effect of photoperiod on Crassulacean acid metabolism (CAM) in Kalanchoe blossfeldiana Poellniz, cv. Tom Thumb, has characteristics similar to its effect on flowering in this plant (although these two phenomena are not causally related). The photoperiodic control of CAM is based on (a) dependance on phytochrome, (b) an endogenous circadian rhythm of sensitivity to photoperiodic signals, (c) a balance between specific positive (increase in enzyme capacity) and negative (inhibitory substances) effects of the photoperiod. Variations in malate content, capacity of phosphoenolpyruvate (PEP) carboxylase, and capacity of CAM inhibitors in young leaves were measured under photoperiodic conditions noninductive for CAM and after transfer into photoperiodic conditions inductive for CAM. Essential characteristics of the photoperiodic induction of CAM are: 1) lag time for malate accumulation; 2) after-effect of the inductive photoperiod on the malate accumulation, on the increase in PEP carboxylase capacity, and on the decrease in the level of long-day produced inhibitors; final levels of malate, enzyme capacity and inhibitor are proportional to the number of inductive day-night cycles; 3) cireadian rhythm in PEP carboxylase capacity with a fixed phase under noninductive photoperiods and a continuously shifting phase under inductive photoperiods, after complex advancing and delaying transients. Kinetic similarities indicate that photoperiodic control of different physiological functions, namely, CAM and flowering, may be achieved through similar mechanisms. Preliminary results with species of Bryophyllum and Sedum support this hypothesis. Phase relationships suggest different degrees of coupling between endogenous enzymic rhythm and photoperiod, depending on whether the plants are under long days or short days.

Leaf habit and woodiness regulate different leaf economy traits at a given nutrient supply.

Science.gov (United States)

Ordoñez, Jenny C; van Bodegom, Peter M; Witte, Jan-Philip M; Bartholomeus, Ruud P; van Dobben, Han F; Aerts, Rien

2010-11-01

The large variation in the relationships between environmental factors and plant traits observed in natural communities exemplifies the alternative solutions that plants have developed in response to the same environmental limitations. Qualitative attributes, such as growth form, woodiness, and leaf habit can be used to approximate these alternative solutions. Here, we quantified the extent to which these attributes affect leaf trait values at a given resource supply level, using measured plant traits from 105 different species (254 observations) distributed across 50 sites in mesic to wet plant communities in The Netherlands. For each site, soil total N, soil total P, and water supply estimates were obtained by field measurements and modeling. Effects of growth forms, woodiness, and leaf habit on relations between leaf traits (SLA, specific leaf area; LNC, leaf nitrogen concentration; and LPC, leaf phosphorus concentration) vs. nutrient and water supply were quantified using maximum-likelihood methods and Bonferroni post hoc tests. The qualitative attributes explained 8-23% of the variance within sites in leaf traits vs. soil fertility relationships, and therefore they can potentially be used to make better predictions of global patterns of leaf traits in relation to nutrient supply. However, at a given soil fertility, the strength of the effect of each qualitative attribute was not the same for all leaf traits. These differences may imply a differential regulation of the leaf economy traits at a given nutrient supply, in which SLA and LPC seem to be regulated in accordance to changes in plant size and architecture while LNC seems to be primarily regulated at the leaf level by factors related to leaf longevity.

Effect of Addition of Moringa Leaf By-Product (Leaf-Waste) on ...

African Journals Online (AJOL)

The effects of incorporation of Moringa leaf fibre (a by-product of leaf processing which contains 24% Crude Fibre by dry weight at 0, 5 and 10 % substitution of wheat flour in cookies was investigated. Three products containing wheat flour: Moringa leaf fibre ratios of 100:0, 95:5, and 90:10 respectively were prepared, and a ...

Autoregulation of kinase dephosphorylation by ATP binding in AGC protein kinases.

Science.gov (United States)

Chan, Tung O; Pascal, John M; Armen, Roger S; Rodeck, Ulrich

2012-02-01

AGC kinases, including the three Akt (protein kinase B) isoforms, protein kinase A (PKA) and all protein kinase C (PKC) isoforms, require activation loop phosphorylation (threonine 308 in Akt1) as well as phosphorylation of a C-terminal residue (serine 473 in Akt1) for catalytic activity and phosphorylation of downstream targets. Conversely, phosphatases reverse these phosphorylations. Virtually all cellular processes are affected by AGC kinases, a circumstance that has led to intense scrutiny of the molecular mechanisms that regulate phosphorylation of these kinases. Here, we review a new layer of control of phosphorylation in Akt, PKA and PKC pointing to ATP binding pocket occupancy as a means to decelerate dephosphorylation of these and, potentially, other kinases. This additional level of kinase regulation opens the door to search for new functional motifs for the rational design of non- ATP-competitive kinase inhibitors that discriminate within and between protein kinase families.

Antagonistic actions of boron against inhibitory effects of aluminum toxicity on growth, CO2 assimilation, ribulose-1,5-bisphosphate carboxylase/oxygenase, and photosynthetic electron transport probed by the JIP-test, of Citrus grandis seedlings

Directory of Open Access Journals (Sweden)

Tang Ning

2009-08-01

Full Text Available Abstract Background Little information is available on the amelioration of boron (B on aluminum (Al-induced photosynthesis inhibition. Sour pummelo (Citrus grandis seedlings were irrigated for 18 weeks with nutrient solution containing 4 B levels (2.5, 10, 25 and 50 μM H3BO3 × 2 Al levels (0 and 1.2 mM AlCl3·6H2O. The objectives of this study were to determine how B alleviates Al-induced growth inhibition and to test the hypothesis that Al-induced photosynthesis inhibition can be alleviated by B via preventing Al from getting into shoots. Results B had little effect on plant growth, root, stem and leaf Al, leaf chlorophyll (Chl, CO2 assimilation, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, Chl a fluorescence (OJIP transient and related parameters without Al stress except that root, stem and leaf B increased with increasing B supply and that 50 μM B decreased slightly root dry weight. Al-treated roots, stems and leaves displayed a higher or similar B. B did not affect root Al under Al stress, but decreased stem and leaf Al level. Shoot growth is more sensitive to Al stress than root growth, CO2 assimilation, Chl, Rubisco, OJIP transient and most related parameters. Al-treated leaves showed decreased CO2 assimilation, but increased or similar intercellular CO2 concentration. Both initial and total Rubisco activity in Al-treated leaves decreased to a lesser extent than CO2 assimilation. Al decreased maximum quantum yield of primary photochemistry and total performance index, but increased minimum fluorescence, K-band, relative variable fluorescence at J- and I-steps. B could alleviate Al-induced increase or decrease for all these parameters. Generally speaking, the order of B effectiveness was 25 μM > 10 μM ≥ 50 μM (excess B > 2.5 μM. Conclusion We propose that Al-induced photosynthesis inhibition was mainly caused by impaired photosynthetic electron transport chain, which may be associated with growth inhibition. B

Global variability in leaf respiration in relation to climate and leaf traits

Science.gov (United States)

Atkin, Owen K.

2015-04-01

Leaf respiration plays a vital role in regulating ecosystem functioning and the Earth's climate. Because of this, it is imperative that that Earth-system, climate and ecosystem-level models be able to accurately predict variations in rates of leaf respiration. In the field of photosynthesis research, the F/vC/B model has enabled modellers to accurately predict variations in photosynthesis through time and space. By contrast, we lack an equivalent biochemical model to predict variations in leaf respiration. Consequently, we need to rely on phenomenological approaches to model variations in respiration across the Earth's surface. Such approaches require that we develop a thorough understanding of how rates of respiration vary among species and whether global environmental gradients play a role in determining variations in leaf respiration. Dealing with these issues requires that data sets be assembled on rates of leaf respiration in biomes across the Earth's surface. In this talk, I will use a newly-assembled global database on leaf respiration and associated traits (including photosynthesis) to highlight variation in leaf respiration (and the balance between respiration and photosynthesis) across global gradients in growth temperature and aridity.

Antidiabetic effect of gomisin N via activation of AMP-activated protein kinase.

Science.gov (United States)

Jung, Dae Young; Kim, Ji-Hyun; Lee, Hoyoung; Jung, Myeong Ho

2017-12-16

Gomisin N (GN) is a lignan derived from Schisandra chinensis. AMP-activated kinase (AMPK) has gained attention as a therapeutic target for the treatment of metabolic syndrome. Previously, we reported that GN activated the AMPK pathway and ameliorated high-fat diet (HFD)-induced hepatic steatosis. In this study, we investigated the anti-diabetic effects of GN in C2C12 myotubes and HFD obese mice. GN enhanced the phosphorylation of AMPK/acetyl-CoA carboxylase (ACC) and Akt. In addition, GN promoted glucose uptake in C2C12 myotubes, which was accompanied by the translocation of glucose transporter 4 (GLUT4) to the plasma membrane. Treatment with compound C, an AMPK inhibitor, suppressed GN-mediated stimulation of glucose uptake. Furthermore, GN increased the expression of mitochondria biogenesis and fatty acid oxidation genes in C2C12 myotubes. In the in vivo study, administration of GN to HFD mice decreased the levels of fasting blood glucose and insulin, and improved glucose tolerance in HFD obese mice. GN administration rescued the decreased phosphorylation of AMPK and Akt and stimulated the expression of mitochondria biogenesis genes in the skeletal muscle of HFD mice. These findings suggested that GN exerted anti-hyperglycemic effects through AMPK activation. Copyright © 2017 Elsevier Inc. All rights reserved.

Autoregulation of kinase dephosphorylation by ATP binding to AGC protein kinases

Science.gov (United States)

Pascal, John M; Armen, Roger S

2012-01-01

AGC kinases, including the three Akt (protein kinase B) isoforms, protein kinase A (PKA) and all protein kinase C (PKC) isoforms, require activation loop phosphorylation (threonine 308 in Akt1) as well as phosphorylation of a C-terminal residue (serine 473 in Akt1) for catalytic activity and phosphorylation of downstream targets. Conversely, phosphatases reverse these phosphorylations. Virtually all cellular processes are affected by AGC kinases, a circumstance that has led to intense scrutiny of the molecular mechanisms that regulate phosphorylation of these kinases. Here, we review a new layer of control of phosphorylation in Akt, PKA and PKC pointing to ATP binding pocket occupancy as a means to decelerate dephosphorylation of these and, potentially, other kinases. This additional level of kinase regulation opens the door to search for new functional motifs for the rational design of non-ATP-competitive kinase inhibitors that discriminate within and between protein kinase families. PMID:22262182

Effect of nitrogen supply on leaf appearance, leaf growth, leaf nitrogen economy and photosynthetic capacity in maize (Zea mays L.)

NARCIS (Netherlands)

Vos, J.; Putten, van der P.E.L.; Birch, C.J.

2005-01-01

Leaf area growth and nitrogen concentration per unit leaf area, Na (g m-2 N) are two options plants can use to adapt to nitrogen limitation. Previous work indicated that potato (Solanum tuberosum L.) adapts the size of leaves to maintain Na and photosynthetic capacity per unit leaf area. This paper

Protein Kinase Mitogen-activated Protein Kinase Kinase Kinase Kinase 4 (MAP4K4) Promotes Obesity-induced Hyperinsulinemia.

Science.gov (United States)

Roth Flach, Rachel J; Danai, Laura V; DiStefano, Marina T; Kelly, Mark; Menendez, Lorena Garcia; Jurczyk, Agata; Sharma, Rohit B; Jung, Dae Young; Kim, Jong Hun; Kim, Jason K; Bortell, Rita; Alonso, Laura C; Czech, Michael P

2016-07-29

Previous studies revealed a paradox whereby mitogen-activated protein kinase kinase kinase kinase 4 (Map4k4) acted as a negative regulator of insulin sensitivity in chronically obese mice, yet systemic deletion of Map4k4 did not improve glucose tolerance. Here, we report markedly reduced glucose-responsive plasma insulin and C-peptide levels in whole body Map4k4-depleted mice (M4K4 iKO) as well as an impaired first phase of insulin secretion from islets derived from M4K4 iKO mice ex vivo After long-term high fat diet (HFD), M4K4 iKO mice pancreata also displayed reduced β cell mass, fewer proliferating β cells and reduced islet-specific gene mRNA expression compared with controls, although insulin content was normal. Interestingly, the reduced plasma insulin in M4K4 iKO mice exposed to chronic (16 weeks) HFD was not observed in response to acute HFD challenge or short term treatment with the insulin receptor antagonist S961. Furthermore, the improved insulin sensitivity in obese M4K4 iKO mice was abrogated by high exogenous insulin over the course of a euglycemic clamp study, indicating that hypoinsulinemia promotes insulin sensitivity in chronically obese M4K4 iKO mice. These results demonstrate that protein kinase Map4k4 drives obesity-induced hyperinsulinemia and insulin resistance in part by promoting insulin secretion from β cells in mice. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

SU-F-T-350: Continuous Leaf Optimization (CLO) for IMRT Leaf Sequencing

Energy Technology Data Exchange (ETDEWEB)

Long, T; Chen, M; Jiang, S; Lu, W [UT Southwestern Medical Center, Dallas, TX (United States)

2016-06-15

Purpose: To study a new step-and-shoot IMRT leaf sequencing model that avoids the two main pitfalls of conventional leaf sequencing: (1) target fluence being stratified into a fixed number of discrete levels and/or (2) aperture leaf positions being restricted to a discrete set of locations. These assumptions induce error into the sequence or reduce the feasible region of potential plans, respectively. Methods: We develop a one-dimensional (single leaf pair) methodology that does not make assumptions (1) or (2) that can be easily extended to a multi-row model. The proposed continuous leaf optimization (CLO) methodology takes in an existing set of apertures and associated intensities, or solution “seed,” and improves the plan without the restrictiveness of 1or (2). It then uses a first-order descent algorithm to converge onto a locally optimal solution. A seed solution can come from models that assume (1) and (2), thus allowing the CLO model to improve upon existing leaf sequencing methodologies. Results: The CLO model was applied to 208 generated target fluence maps in one dimension. In all cases for all tested sequencing strategies, the CLO model made improvements on the starting seed objective function. The CLO model also was able to keep MUs low. Conclusion: The CLO model can improve upon existing leaf sequencing methods by avoiding the restrictions of (1) and (2). By allowing for more flexible leaf positioning, error can be reduced when matching some target fluence. This study lays the foundation for future models and solution methodologies that can incorporate continuous leaf positions explicitly into the IMRT treatment planning model. Supported by Cancer Prevention & Research Institute of Texas (CPRIT) - ID RP150485.

Kinases and Cancer

OpenAIRE

Jonas Cicenas; Egle Zalyte; Amos Bairoch; Pascale Gaudet

2018-01-01

Protein kinases are a large family of enzymes catalyzing protein phosphorylation. The human genome contains 518 protein kinase genes, 478 of which belong to the classical protein kinase family and 40 are atypical protein kinases [...

Rewiring the reductive tricarboxylic acid pathway and L-malate transport pathway of Aspergillus oryzae for overproduction of L-malate.

Science.gov (United States)

Liu, Jingjing; Xie, Zhipeng; Shin, Hyun-Dong; Li, Jianghua; Du, Guocheng; Chen, Jian; Liu, Long

2017-07-10

Aspergillus oryzae finds wide application in the food, feed, and wine industries, and is an excellent cell factory platform for production of organic acids. In this work, we achieved the overproduction of L-malate by rewiring the reductive tricarboxylic acid (rTCA) pathway and L-malate transport pathway of A. oryzae NRRL 3488. First, overexpression of native pyruvate carboxylase and malate dehydrogenase in the rTCA pathway improved the L-malate titer from 26.1gL -1 to 42.3gL -1 in shake flask culture. Then, the oxaloacetate anaplerotic reaction was constructed by heterologous expression of phosphoenolpyruvate carboxykinase and phosphoenolpyruvate carboxylase from Escherichia coli, increasing the L-malate titer to 58.5gL -1 . Next, the export of L-malate from the cytoplasm to the external medium was strengthened by overexpression of a C4-dicarboxylate transporter gene from A. oryzae and an L-malate permease gene from Schizosaccharomyces pombe, improving the L-malate titer from 58.5gL -1 to 89.5gL -1 . Lastly, guided by transcription analysis of the expression profile of key genes related to L-malate synthesis, the 6-phosphofructokinase encoded by the pfk gene was identified as a potential limiting step for L-malate synthesis. Overexpression of pfk with the strong sodM promoter increased the L-malate titer to 93.2gL -1 . The final engineered A. oryzae strain produced 165gL -1 L-malate with a productivity of 1.38gL -1 h -1 in 3-L fed-batch culture. Overall, we constructed an efficient L-malate producer by rewiring the rTCA pathway and L-malate transport pathway of A. oryzae NRRL 3488, and the engineering strategy adopted here may be useful for the construction of A. oryzae cell factories to produce other organic acids. Copyright © 2017 Elsevier B.V. All rights reserved.

On the temporal variation of leaf magnetic parameters: seasonal accumulation of leaf-deposited and leaf-encapsulated particles of a roadside tree crown.

Science.gov (United States)

Hofman, Jelle; Wuyts, Karen; Van Wittenberghe, Shari; Samson, Roeland

2014-09-15

Understanding the accumulation behaviour of atmospheric particles inside tree leaves is of great importance for the interpretation of biomagnetic monitoring results. In this study, we evaluated the temporal variation of the saturation isothermal remanent magnetisation (SIRM) of leaves of a roadside urban Platanus × acerifolia Willd. tree in Antwerp, Belgium. We hereby examined the seasonal development of the total leaf SIRM signal as well as the leaf-encapsulated fraction of the deposited dust, by washing the leaves before biomagnetic analysis. On average 38% of the leaf SIRM signal was exhibited by the leaf-encapsulated particles. Significant correlations were found between the SIRM and the cumulative daily average atmospheric PM10 and PM2.5 measurements. Moreover, a steady increase of the SIRM throughout the in-leaf season was observed endorsing the applicability of biomagnetic monitoring as a proxy for the time-integrated PM exposure of urban tree leaves. Strongest correlations were obtained for the SIRM of the leaf-encapsulated particles which confirms the dynamic nature of the leaf surface-accumulated particles. Copyright © 2014 Elsevier B.V. All rights reserved.

Fe deficiency induced changes in rice (Oryza sativa L.) thylakoids.

Science.gov (United States)

Wang, Yuwen; Xu, Chao; Li, Kang; Cai, Xiaojie; Wu, Min; Chen, Guoxiang

2017-01-01

Iron deficiency is an important abiotic stress that limits productivity of crops all over the world. We selected a hybrid rice (Oryza sativa L.), LYPJ, which is super high-yield and widely cultured in China, to investigate changes in the components and structure of thylakoid membranes and photosynthetic performance in response to iron deficiency. Our results demonstrated that photosystem I (PSI) is the primary target for iron deficiency, while the changes in photosystem II (PSII) are important for rebuilding a balance in disrupted energy utilization and dissipation caused by differential degradation of photosynthetic components. The result of immunoblot analysis suggested that the core subunit PsaA declined drastically, while PsbA remained relatively stable. Furthermore, several organizational changes of the photosynthetic apparatus were found by BN-PAGE, including a marked decrease in the PSI core complexes, the Cytb 6 /f complex, and the trimeric form of the LHCII antenna, consistent with the observed unstacking grana. The fluorescence induction analysis indicated a descending PSII activity with energy dissipation enhanced markedly. In addition, we proposed that the crippled CO 2 assimilation could be compensated by the enhanced of phosphoenolpyruvate carboxylase (PEPC), which is suggested by the decreased ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and photosynthetic efficiency.

Elevated CO{sub 2} does not ameliorate effects of ozone on carbon allocation in Pinus halepensis and Betula pendula in symbiosis with Paxillus involutus

Energy Technology Data Exchange (ETDEWEB)

Kytoeviita, M.M. [Oulu Univ., Dept. of Biology, Oulu (Finland); Pelloux, J.; Fontaine, V.; Botton, B.; Dizengremel, P. [Univ. Henri Poincare-Nancy, Lab. de Biologie Forestiere Associe INRA, Vandoeuvre-les-Nancy (France)

1999-07-01

The effect of 700 {mu}mol CO{sub 2} mol{sup -1}, 200 nmol ozone mol{sup -1} and a combination of the two on carbon allocation was examined in Pinus halepensis co-cultured with Betula pendula in symbiosis with the ectomycorrhizal fungus Paxillus involutus. The results show that under low nutrient and ozone levels, elevated CO{sub 2} has no effect on the growth of B. pendula or P. halepensis seedlings nor on net carbon partitioning between plant parts. Elevated CO{sub 2} did not enhance the growth of the fungus in symbiosis with the birch. On the other hand, ozone had a strong negative effect on the growth of the birch, which corresponded with the significantly reduced growth rates of the fungus. Exposure to elevated CO{sub 2} did not ameliorate the negative effects of ozone on birch; in contrast, it acted as an additional stress factor. Neither ozone nor CO{sub 2} had significant effects on biomass accumulation in the pine seedlings. Ozone stimulated the spread of mycorrhizal infection from the birch seedlings to neighbouring pines and had no statistically significant effects on phosphoenolpyruvate carboxylase (PEPC) or ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity in the pine needles or on PEPC activity in pine roots. (au)

Cell cycle regulation of the BRCA1/acetyl-CoA-carboxylase complex.

Science.gov (United States)

Ray, H; Suau, F; Vincent, A; Dalla Venezia, N

2009-01-16

Germ-line alterations in BRCA1 are associated with an increased susceptibility to breast and ovarian cancer. The BRCA1 protein has been implicated in multiple cellular functions. We have recently demonstrated that BRCA1 reduces acetyl-CoA-carboxylase alpha (ACCA) activity through its phospho-dependent binding to ACCA, and further established that the phosphorylation of the Ser1263 of ACCA is required for this interaction. Here, to gain more insight into the cellular conditions that trigger the BRCA1/ACCA interaction, we designed an anti-pSer1263 antibody and demonstrated that the Ser1263 of ACCA is phosphorylated in vivo, in a cell cycle-dependent manner. We further showed that the interaction between BRCA1 and ACCA is regulated during cell cycle progression. Taken together, our findings reveal a novel mechanism of regulation of ACCA distinct from the previously described phosphorylation of Ser79, and provide new insights into the control of lipogenesis through the cell cycle.

Effect of Wind on the Relation of Leaf N, P Stoichiometry with Leaf Morphology in Quercus Species

Directory of Open Access Journals (Sweden)

Peng Zhang

2018-02-01

Full Text Available Leaf nitrogen (N and phosphorus (P stoichiometry correlates closely to leaf morphology, which is strongly impacted by wind at multiple scales. However, it is not clear how leaf N, P stoichiometry and its relationship to leaf morphology changes with wind load. We determined the leaf N and P concentrations and leaf morphology—including specific leaf area (SLA and leaf dissection index (LDI—for eight Quercus species under a simulated wind load for seven months. Leaf N and P concentrations increased significantly under these conditions for Quercus acutissima, Quercus rubra, Quercus texana, and Quercus palustris—which have elliptic leaves—due to their higher N, P requirements and a resultant leaf biomass decrease, which is a tolerance strategy for Quercus species under a wind load. Leaf N:P was relatively stable under wind for all species, which supports stoichiometric homeostasis. Leaf N concentrations showed a positive correlation to SLA, leaf N and P concentrations showed positive correlations to LDI under each wind treatment, and the slope of correlations was not affected by wind, which indicates synchronous variations between leaf stoichiometry and leaf morphology under wind. However, the intercept of correlations was affected by wind, and leaf N and P use efficiency decreased under the wind load, which suggests that the Quercus species changes from “fast investment-return” in the control to “slow investment-return” under windy conditions. These results will be valuable to understanding functional strategies for plants under varying wind loads, especially synchronous variations in leaf traits along a wind gradient.

Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

Directory of Open Access Journals (Sweden)

BRUNO H.P. ROSADO

2013-09-01

Full Text Available During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

Science.gov (United States)

Rosado, Bruno H P; De Mattos, Eduardo A; Sternberg, Leonel Da S L

2013-09-01

During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

Higher protein kinase C ζ in fatty rat liver and its effect on insulin actions in primary hepatocytes.

Directory of Open Access Journals (Sweden)

Wei Chen

Full Text Available We previously showed the impairment of insulin-regulated gene expression in the primary hepatocytes from Zucker fatty (ZF rats, and its association with alterations of hepatic glucose and lipid metabolism. However, the molecular mechanism is unknown. A preliminary experiment shows that the expression level of protein kinase C ζ (PKCζ, a member of atypical PKC family, is higher in the liver and hepatocytes of ZF rats than that of Zucker lean (ZL rats. Herein, we intend to investigate the roles of atypical protein kinase C in the regulation of hepatic gene expression. The insulin-regulated hepatic gene expression was evaluated in ZL primary hepatocytes treated with atypical PKC recombinant adenoviruses. Recombinant adenovirus-mediated overexpression of PKCζ, or the other atypical PKC member PKCι/λ, alters the basal and impairs the insulin-regulated expressions of glucokinase, sterol regulatory element-binding protein 1c, the cytosolic form of phosphoenolpyruvate carboxykinase, the catalytic subunit of glucose 6-phosphatase, and insulin like growth factor-binding protein 1 in ZL primary hepatocytes. PKCζ or PKCι/λ overexpression also reduces the protein level of insulin receptor substrate 1, and the insulin-induced phosphorylation of AKT at Ser473 and Thr308. Additionally, PKCι/λ overexpression impairs the insulin-induced Prckz expression, indicating the crosstalk between PKCζ and PKCι/λ. We conclude that the PKCζ expression is elevated in hepatocytes of insulin resistant ZF rats. Overexpressions of aPKCs in primary hepatocytes impair insulin signal transduction, and in turn, the down-stream insulin-regulated gene expression. These data suggest that elevation of aPKC expression may contribute to the hepatic insulin resistance at gene expression level.

How do leaf veins influence the worldwide leaf economic spectrum? Review and synthesis.

Science.gov (United States)

Sack, Lawren; Scoffoni, Christine; John, Grace P; Poorter, Hendrik; Mason, Chase M; Mendez-Alonzo, Rodrigo; Donovan, Lisa A

2013-10-01

Leaf vein traits are implicated in the determination of gas exchange rates and plant performance. These traits are increasingly considered as causal factors affecting the 'leaf economic spectrum' (LES), which includes the light-saturated rate of photosynthesis, dark respiration, foliar nitrogen concentration, leaf dry mass per area (LMA) and leaf longevity. This article reviews the support for two contrasting hypotheses regarding a key vein trait, vein length per unit leaf area (VLA). Recently, Blonder et al. (2011, 2013) proposed that vein traits, including VLA, can be described as the 'origin' of the LES by structurally determining LMA and leaf thickness, and thereby vein traits would predict LES traits according to specific equations. Careful re-examination of leaf anatomy, published datasets, and a newly compiled global database for diverse species did not support the 'vein origin' hypothesis, and moreover showed that the apparent power of those equations to predict LES traits arose from circularity. This review provides a 'flux trait network' hypothesis for the effects of vein traits on the LES and on plant performance, based on a synthesis of the previous literature. According to this hypothesis, VLA, while virtually independent of LMA, strongly influences hydraulic conductance, and thus stomatal conductance and photosynthetic rate. We also review (i) the specific physiological roles of VLA; (ii) the role of leaf major veins in influencing LES traits; and (iii) the role of VLA in determining photosynthetic rate per leaf dry mass and plant relative growth rate. A clear understanding of leaf vein traits provides a new perspective on plant function independently of the LES and can enhance the ability to explain and predict whole plant performance under dynamic conditions, with applications towards breeding improved crop varieties.

A system dynamics model integrating physiology and biochemical regulation predicts extent of crassulacean acid metabolism (CAM) phases.

Science.gov (United States)

Owen, Nick A; Griffiths, Howard

2013-12-01

A system dynamics (SD) approach was taken to model crassulacean acid metabolism (CAM) expression from measured biochemical and physiological constants. SD emphasizes state-dependent feedback interaction to describe the emergent properties of a complex system. These mechanisms maintain biological systems with homeostatic limits on a temporal basis. Previous empirical studies on CAM have correlated biological constants (e.g. enzyme kinetic parameters) with expression over the CAM diel cycle. The SD model integrates these constants within the architecture of the CAM 'system'. This allowed quantitative causal connections to be established between biological inputs and the four distinct phases of CAM delineated by gas exchange and malic acid accumulation traits. Regulation at flow junctions (e.g. stomatal and mesophyll conductance, and malic acid transport across the tonoplast) that are subject to feedback control (e.g. stomatal aperture, malic acid inhibition of phosphoenolpyruvate carboxylase, and enzyme kinetics) was simulated. Simulated expression for the leaf-succulent Kalanchoë daigremontiana and more succulent tissues of Agave tequilana showed strong correlation with measured gas exchange and malic acid accumulation (R(2)  = 0.912 and 0.937, respectively, for K. daigremontiana and R(2)  = 0.928 and 0.942, respectively, for A. tequilana). Sensitivity analyses were conducted to quantitatively identify determinants of diel CO2 uptake. The transition in CAM expression from low to high volume/area tissues (elimination of phase II-IV carbon-uptake signatures) was achieved largely by the manipulation three input parameters. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Metabolic origin of the {delta}{sup 13}C of respired CO{sub 2} in roots of Phaseolus vulgaris

Energy Technology Data Exchange (ETDEWEB)

Bathellier, C.; Tcherkez, G.; Cornic, G.; Ghashghaie, J. [Laboratoire d' Ecologie, Systematique et Evolution - ESE, CNRS-UMR 8079 - IFR 87, Batiment 362, Universite Paris-Sud, 91405-Orsay Cedex (France); Tcherkez, G. [Plateforme Metabolisme-Metabolome, IFR87 La Plante et son Environnement, Institut de Biotechnologie des Plantes, Batiment 630, Universite Paris-Sud, 91405-Orsay Cedex (France); Bligny, R.; Gout, E. [Laboratoire de Physiologie Cellulaire Vegetale CEA-Grenoble 17, rue des Martyrs, 38054 Grenoble Cedex 9 (France)

2009-07-01

- Root respiration is a major contributor to soil CO{sub 2} efflux, and thus an important component of ecosystem respiration. But its metabolic origin, in relation to the carbon isotope composition ({delta}{sup 13}C), remains poorly understood. - Here, {sup 13}C analysis was conducted on CO{sub 2} and metabolites under typical conditions or under continuous darkness in French bean (Phaseolus vulgaris) roots. {sup 13}C contents were measured either under natural abundance or following pulse-chase labeling with {sup 13}C-enriched glucose or pyruvate, using isotope ratio mass spectrometer (IRMS) and nuclear magnetic resonance (NMR) techniques. - In contrast to leaves, no relationship was found between the respiratory quotient and the {delta}{sup 13}C of respired CO{sub 2}, which stayed constant at a low value (c. -27.5 per thousand) under continuous darkness. With labeling experiments, it is shown that such a pattern is explained by the {sup 13}C-depleting effect of the pentose phosphate pathway; and the involvement of the Krebs cycle fueled by either the glycolytic input or the lipid/protein recycling. The anaplerotic phosphoenolpyruvate carboxylase (PEPc) activity sustained glutamic acid (Glu) synthesis, with no net effect on respired CO{sub 2}. - These results indicate that the root {delta}{sup 13}C signal does not depend on the availability of root respiratory substrates and it is thus plausible that, unless the {sup 13}C photosynthetic fractionation varies at the leaf level, the root {delta}{sup 13}C signal hardly changes under a range of natural environmental conditions. (authors)

An evolutionary perspective on leaf economics : Phylogenetics of leaf mass per area in vascular plants

NARCIS (Netherlands)

Flores, Olivier; Garnier, Eric; Wright, Ian J.; Reich, Peter B.; Pierce, Simon; Diaz, Sandra; Pakeman, Robin J.; Rusch, Graciela M.; Bernard-Verdier, Maud; Testi, Baptiste; Bakker, Jan P.; Bekker, Renee M.; Cerabolini, Bruno E. L.; Ceriani, Roberta M.; Cornu, Guillaume; Cruz, Pablo; Delcamp, Matthieu; Dolezal, Jiri; Eriksson, Ove; Fayolle, Adeline; Freitas, Helena; Golodets, Carly; Gourlet-Fleury, Sylvie; Hodgson, John G.; Brusa, Guido; Kleyer, Michael; Kunzmann, Dieter; Lavorel, Sandra; Papanastasis, Vasilios P.; Perez-Harguindeguy, Natalia; Vendramini, Fernanda; Weiher, Evan

In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This "worldwide leaf economics spectrum" consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf

Light-regulated phosphorylation of maize phosphoenolpyruvate carboxykinase plays a vital role in its activity.

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Chao, Qing; Liu, Xiao-Yu; Mei, Ying-Chang; Gao, Zhi-Fang; Chen, Yi-Bo; Qian, Chun-Rong; Hao, Yu-Bo; Wang, Bai-Chen

2014-05-01

Phosphoenolpyruvate carboxykinase (PEPCK)-the major decarboxylase in PEPCK-type C4 plants-is also present in appreciable amounts in the bundle sheath cells of NADP-malic enzyme-type C4 plants, such as maize (Zea mays), where it plays an apparent crucial role during photosynthesis (Wingler et al., in Plant Physiol 120(2):539-546, 1999; Furumoto et al., in Plant Mol Biol 41(3):301-311, 1999). Herein, we describe the use of mass spectrometry to demonstrate phosphorylation of maize PEPCK residues Ser55, Thr58, Thr59, and Thr120. Western blotting indicated that the extent of Ser55 phosphorylation dramatically increases in the leaves of maize seedlings when the seedlings are transferred from darkness to light, and decreases in the leaves of seedlings transferred from light to darkness. The effect of light on phosphorylation of this residue is opposite that of the effect of light on PEPCK activity, with the decarboxylase activity of PEPCK being less in illuminated leaves than in leaves left in the dark. This inverse relationship between PEPCK activity and the extent of phosphorylation suggests that the suppressive effect of light on PEPCK decarboxylation activity might be mediated by reversible phosphorylation of Ser55.

Regulatory enzymes of mitochondrial beta-oxidation as targets for treatment of the metabolic syndrome

NARCIS (Netherlands)

Schreurs, M.; Kuipers, F.; van der Leij, F. R.

P>Insulin sensitizers like metformin generally act through pathways triggered by adenosine monophosphate-activated protein kinase. Carnitine palmitoyltransferase 1 (CPT1) controls mitochondrial beta-oxidation and is inhibited by malonyl-CoA, the product of acetyl-CoA carboxylase (ACC). The adenosine

Identification of Ser-543 as the major regulatory phosphorylation site in spinach leaf nitrate reductase

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Bachmann, M.; Shiraishi, N.; Campbell, W. H.; Yoo, B. C.; Harmon, A. C.; Huber, S. C.; Davies, E. (Principal Investigator)

1996-01-01

Spinach leaf NADH:nitrate reductase (NR) responds to light/dark signals and photosynthetic activity in part as a result of rapid regulation by reversible protein phosphorylation. We have identified the major regulatory phosphorylation site as Ser-543, which is located in the hinge 1 region connecting the cytochrome b domain with the molybdenum-pterin cofactor binding domain of NR, using recombinant NR fragments containing or lacking the phosphorylation site sequence. Studies with NR partial reactions indicated that the block in electron flow caused by phosphorylation also could be localized to the hinge 1 region. A synthetic peptide (NR6) based on the phosphorylation site sequence was phosphorylated readily by NR kinase (NRk) in vitro. NR6 kinase activity tracked the ATP-dependent inactivation of NR during several chromatographic steps and completely inhibited inactivation/phosphorylation of native NR in vitro. Two forms of NRk were resolved by using anion exchange chromatography. Studies with synthetic peptide analogs indicated that both forms of NRk had similar specificity determinants, requiring a basic residue at P-3 (i.e., three amino acids N-terminal to the phosphorylated serine) and a hydrophobic residue at P-5. Both forms are strictly calcium dependent but belong to distinct families of protein kinases because they are distinct immunochemically.

Photosynthetic /sup 14/CO/sub 2/ fixation in the leaves of rice and some other species

Energy Technology Data Exchange (ETDEWEB)

Ishii, R; Samejima, M; Murata, Y [Tokyo Univ. (Japan). Faculty of Agriculture

1977-03-01

The activity of CO/sub 2/-fixing enzymes and the initial products of photosynthetic /sup 14/CO/sub 2/ fixation in two rice varieties, the one japonica and the other indica, were examined, comparing with those in several C/sub 3/ and C/sub 4/ crop species. Corn and barnyard grass as C/sub 4/ plants and barley and wheat as C/sub 3/ plants were used as comparison materials. The plants were cultured at 25 deg. C in daytime and 20 deg. C in night under natural light in a phytotron. After about a month from sowing, the fully expanded leaf blades were subjected to the experiments. The fresh leaf blades of one gram were homogenized in 5 ml of 50 mM Tris-H/sub 2/SO/sub 4/ buffer (pH 7.7) containing 4 mM EDTA, 10 mM dithiothreitol and 50 mg of polyamide powder. After filtration, the supernatant was used as the crude enzyme extract for assaying the activity of RuDP carboxylase and PEP carboxylase. The experiments revealed that (1) in C/sub 3/ plants, the RuDP carboxylase activity was higher, and the PEP carboxylase activity was lower than those in C/sub 4/ plants; (2) the initial products of photosynthetic /sup 14/CO/sub 2/ fixation in the japonica rice variety were mainly PGA and other sugar phosphates as in barley, whereas in corn, they were malic and aspartic acids; (3) the /sup 14/C incorporation into glycine and serine was high in the japonica rice and barley, whereas low in corn. From these results, rice could be regarded as C/sub 3/ plant.

Easy Leaf Area: Automated digital image analysis for rapid and accurate measurement of leaf area.

Science.gov (United States)

Easlon, Hsien Ming; Bloom, Arnold J

2014-07-01

Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. • Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. • Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images.

Acetyl CoA Carboxylase 2 Is Dispensable for CD8+ T Cell Responses.

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Jang Eun Lee

Full Text Available Differentiation of T cells is closely associated with dynamic changes in nutrient and energy metabolism. However, the extent to which specific metabolic pathways and molecular components are determinative of CD8+ T cell fate remains unclear. It has been previously established in various tissues that acetyl CoA carboxylase 2 (ACC2 regulates fatty acid oxidation (FAO by inhibiting carnitine palmitoyltransferase 1 (CPT1, a rate-limiting enzyme of FAO in mitochondria. Here, we explore the cell-intrinsic role of ACC2 in T cell immunity in response to infections. We report here that ACC2 deficiency results in a marginal increase of cellular FAO in CD8+ T cells, but does not appear to influence antigen-specific effector and memory CD8+ T cell responses during infection with listeria or lymphocytic choriomeningitis virus. These results suggest that ACC2 is dispensable for CD8+ T cell responses.

Leaf anatomical traits determine the 18O enrichment of leaf water in coastal halophytes

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Liang, J.; Lin, G., Sr.; Sternberg, L. O.

2017-12-01

Foliar anatomical adaptations to high-salinity environment in mangroves may be recorded by leaf water isotopes. Recent studies observed that a few mangrove species have lower 18O enrichment of leaf water (ΔL) relative to source water than the adjacent terrestrial trees, but what factors actually control this phenomenon is still disputable at present. To resolve this issue, we collected 15 species of true mangrove plants, 14 species of adjacent freshwater trees and 4 species of semi-mangrove plants at five study sites on the southeastern coast of China. Leaf stomatal density and pore size, water content, ΔL and other related leaf physiological traits were determined for the selected leaves of these plants. Our results confirmed that ΔL values of mangroves were generally 3 4 ‰ lower than those of the adjacent freshwater or semi-mangrove species. Higher leaf water per area (LWC) and lower leaf stomatal density (LS) of mangroves played co-dominant roles in lowering ΔL through elongating effective leaf mixing length by about 20%. The Péclet model incorporated by LWC and LS performed well in predicting ΔL. The demonstrated general law between leaf anatomy and ΔL in this paper based on a large pool of species bridges the gap between leaf functional traits and metabolic proxies derived ΔL, which will have considerable potential applications in vegetation succession and reconstruction of paleoclimate research.

Dark CO/sub 2/ fixation in leaves of tomato plants grown with ammonium and nitrate as nitrogen sources

Energy Technology Data Exchange (ETDEWEB)

Ikeda, M; Yamada, Y [Kyushu Univ., Fukuoka (Japan). Dept. of Agricultural Chemistry

1981-01-01

The dark (non-photosynthetic) CO/sub 2/ fixation was studied in the leaves of ammonium-fed and nitrate-fed tomato plants. The ability to fix /sup 14/CO/sub 2/ in the dark of ammonium-fed plants was remarkably lower as compared with nitrate-fed plants, supporting the previous finding that the synthesis of C/sub 4/-compounds from C/sub 3/-compounds was reduced in the leaves of ammonium-fed plants. There was no difference in the activity of PEP carboxylase in extracts prepared from the leaves between both the plants during an early period of the treatment. However, the enzyme activity began to decrease rapidly in ammonium-fed plants 4 days after the treatment. By long-term treatments, the enzyme activity in ammonium-fed plants became half as high as that of nitrate-fed plants. The decreased PEP carboxylase activity in ammonium-fed plants was not associated with the presence of NH/sub 4/-N and the absence of NO/sub 3/-N in the leaf extract, and was not restored by the addition of the leaf extract from nitrate-fed plants. It is concluded that the decreased rate of synthesis of C/sub 4/-compounds from C/sub 3/-compounds in ammonium-fed plants is closely associated with a decrease in the dark fixation involving PEP carboxylase.

Effects of leaf movement on leaf temperature, transpiration and radiation interception in soybean under water stress conditions

International Nuclear Information System (INIS)

Isoda, A.; Wang, P.

2001-01-01

Varietal differences in leaf movement were examined in terms of radiation interception, leaf temperature and transpiration under water stressed conditions. Five cultivars (Qindou 7232, Gaofei 16, Dongnong 87 - 138, 8285 - 8 and 8874) were grown in a concrete frame field in Xinjiang, China. Irrigation treatments (irrigation and no irrigation) were made from the flowering to the pod filling stage. A leaflet in the uppermost layer of the canopy was restrained horizontally. Leaf temperatures, transpiration rate (stem sap flow rate of the main stem per unit leaf area) and intercepted radiation of each leaflet were measured. There were greater varietal differences in leaf movement, leaf temperature and transpiration rate. Leaf temperature seemed to be adjusted by leaf movement and transpiration. The extent to which is adjusted by leaf movement and transpiration differed among the cultivars; leaf temperature was influenced mainly by leaf movement for Gaofei 16 and Dongnong 87 - 138, mainly by transpiration for Qindou 7232 and 8874, and by both for 8285 - 8. Intercepted radiation in the upper two layers of the canopy (20 cm from the uppermost) was greater in the irrigated plot, although the mean values of total leaflets of the irrigated plot were not different as compared to the non-irrigated plot. Although paraheliotropic leaf movement decreased radiation interception, it offers some possibilities for the improvement in radiation penetration within a dense canopy. Cumulated amount of transpiration during a day was compared between the restrained-leaf and the non-leaf-restrained plants in 8874. Paraheliotropic leaf movement reduced water loss by 23% in the irrigated and 71% in the non-irrigated plots

Molecular interactions between tomato and the leaf mold pathogen Cladosporium fulvum.

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Rivas, Susana; Thomas, Colwyn M

2005-01-01

The interaction between tomato and the leaf mold pathogen Cladosporium fulvum is controlled in a gene-for-gene manner. This interaction has provided useful insights to the molecular basis of recognition specificity in plant disease resistance (R) proteins, disease resistance (R) gene evolution, R-protein mediated signaling, and cellular responses to pathogen attack. Tomato Cf genes encode type I membrane-associated receptor-like proteins (RLPs) comprised predominantly of extracellular leucine-rich repeats (eLRRs) and which are anchored in the plasma membrane. Cf proteins recognize fungal avirulence (Avr) peptides secreted into the leaf apoplast during infection. A direct interaction of Cf proteins with their cognate Avr proteins has not been demonstrated and the molecular mechanism of Avr protein perception is not known. Following ligand perception Cf proteins trigger a hypersensitive response (HR) and the arrest of pathogen development. Cf proteins lack an obvious signaling domain, suggesting that defense response activation is mediated through interactions with other partners. Avr protein perception results in the rapid accumulation of active oxygen species (AOS), changes in cellular ion fluxes, activation of protein kinase cascades, changes in gene expression and, possibly, targeted protein degradation. Here we review our current understanding of Cf-mediated responses in resistance to C. fulvum.

Rapid, high-resolution measurement of leaf area and leaf orientation using terrestrial LiDAR scanning data

International Nuclear Information System (INIS)

Bailey, Brian N; Mahaffee, Walter F

2017-01-01

The rapid evolution of high performance computing technology has allowed for the development of extremely detailed models of the urban and natural environment. Although models can now represent sub-meter-scale variability in environmental geometry, model users are often unable to specify the geometry of real domains at this scale given available measurements. An emerging technology in this field has been the use of terrestrial LiDAR scanning data to rapidly measure the three-dimensional geometry of trees, such as the distribution of leaf area. However, current LiDAR methods suffer from the limitation that they require detailed knowledge of leaf orientation in order to translate projected leaf area into actual leaf area. Common methods for measuring leaf orientation are often tedious or inaccurate, which places constraints on the LiDAR measurement technique. This work presents a new method to simultaneously measure leaf orientation and leaf area within an arbitrarily defined volume using terrestrial LiDAR data. The novelty of the method lies in the direct measurement of the fraction of projected leaf area G from the LiDAR data which is required to relate projected leaf area to total leaf area, and in the new way in which radiation transfer theory is used to calculate leaf area from the LiDAR data. The method was validated by comparing LiDAR-measured leaf area to (1) ‘synthetic’ or computer-generated LiDAR data where the exact area was known, and (2) direct measurements of leaf area in the field using destructive sampling. Overall, agreement between the LiDAR and reference measurements was very good, showing a normalized root-mean-squared-error of about 15% for the synthetic tests, and 13% in the field. (paper)

Leaf endophyte load influences fungal garden development in leaf-cutting ants

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Van Bael Sunshine A

2012-11-01

Full Text Available Abstract Background Previous work has shown that leaf-cutting ants prefer to cut leaf material with relatively low fungal endophyte content. This preference suggests that fungal endophytes exact a cost on the ants or on the development of their colonies. We hypothesized that endophytes may play a role in their host plants’ defense against leaf-cutting ants. To measure the long-term cost to the ant colony of fungal endophytes in their forage material, we conducted a 20-week laboratory experiment to measure fungal garden development for colonies that foraged on leaves with low or high endophyte content. Results Colony mass and the fungal garden dry mass did not differ significantly between the low and high endophyte feeding treatments. There was, however, a marginally significant trend toward greater mass of fungal garden per ant worker in the low relative to the high endophyte treatment. This trend was driven by differences in the fungal garden mass per worker from the earliest samples, when leaf-cutting ants had been foraging on low or high endophyte leaf material for only 2 weeks. At two weeks of foraging, the mean fungal garden mass per worker was 77% greater for colonies foraging on leaves with low relative to high endophyte loads. Conclusions Our data suggest that the cost of endophyte presence in ant forage material may be greatest to fungal colony development in its earliest stages, when there are few workers available to forage and to clean leaf material. This coincides with a period of high mortality for incipient colonies in the field. We discuss how the endophyte-leaf-cutter ant interaction may parallel constitutive defenses in plants, whereby endophytes reduce the rate of colony development when its risk of mortality is greatest.

Easy Leaf Area: Automated Digital Image Analysis for Rapid and Accurate Measurement of Leaf Area

Directory of Open Access Journals (Sweden)

Hsien Ming Easlon

2014-07-01

Full Text Available Premise of the study: Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. Methods and Results: Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. Conclusions: Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images.

Seasonal changes in the expression of energy metabolism-related genes in white adipose tissue and skeletal muscle in female Japanese black bears.

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Shimozuru, Michito; Nagashima, Akiko; Tanaka, Jun; Tsubota, Toshio

2016-01-01

Bears undergo annual cycles in body mass: rapid fattening in autumn (i.e., hyperphagia), and mass loss in winter (i.e., hibernation). To investigate how Japanese black bears (Ursus thibetanus japonicus) adapt to such extreme physiological conditions, we analyzed changes in the mRNA expression of energy metabolism-related genes in white adipose tissues and skeletal muscle throughout three physiological stages: normal activity (June), hyperphagia (November), and hibernation (March). During hyperphagia, quantitative real-time polymerase chain reaction analysis revealed the upregulation of de novo lipogenesis-related genes (e.g., fatty acid synthase and diacylglycerol O-acyltransferase 2) in white adipose tissue, although the bears had been maintained with a constant amount of food. In contrast, during the hibernation period, we observed a downregulation of genes involved in glycolysis (e.g., glucose transporter 4) and lipogenesis (e.g., acetyl-CoA carboxylase 1) and an upregulation of genes in fatty acid catabolism (e.g., carnitine palmitoyltransferase 1A) in both tissue types. In white adipose tissues, we observed upregulation of genes involved in glyceroneogenesis, including pyruvate carboxylase and phosphoenolpyruvate carboxykinase 1, suggesting that white adipose tissue plays a role in the recycling of circulating free fatty acids via re-esterification. In addition, the downregulation of genes involved in amino acid catabolism (e.g., alanine aminotransferase) and the TCA cycle (e.g., pyruvate carboxylase) indicated a role of skeletal muscle in muscle protein sparing and pyruvate recycling via the Cori cycle. These examples of coordinated transcriptional regulation would contribute to rapid mass gain during the pre-hibernation period and to energy preservation and efficient energy production during the hibernation period. Copyright © 2016 Elsevier Inc. All rights reserved.

Oncogenic Receptor Tyrosine Kinases Directly Phosphorylate Focal Adhesion Kinase (FAK) as a Resistance Mechanism to FAK-Kinase Inhibitors.

Science.gov (United States)

Marlowe, Timothy A; Lenzo, Felicia L; Figel, Sheila A; Grapes, Abigail T; Cance, William G

2016-12-01

Focal adhesion kinase (FAK) is a major drug target in cancer and current inhibitors targeted to the ATP-binding pocket of the kinase domain have entered clinical trials. However, preliminary results have shown limited single-agent efficacy in patients. Despite these unfavorable data, the molecular mechanisms that drive intrinsic and acquired resistance to FAK-kinase inhibitors are largely unknown. We have demonstrated that receptor tyrosine kinases (RTK) can directly bypass FAK-kinase inhibition in cancer cells through phosphorylation of FAK's critical tyrosine 397 (Y397). We also showed that HER2 forms a direct protein-protein interaction with the FAK-FERM-F1 lobe, promoting direct phosphorylation of Y397. In addition, FAK-kinase inhibition induced two forms of compensatory RTK reprogramming: (i) the rapid phosphorylation and activation of RTK signaling pathways in RTK High cells and (ii) the long-term acquisition of RTKs novel to the parental cell line in RTK Low cells. Finally, HER2 +: cancer cells displayed resistance to FAK-kinase inhibition in 3D growth assays using a HER2 isogenic system and HER2 + cancer cell lines. Our data indicate a novel drug resistance mechanism to FAK-kinase inhibitors whereby HER2 and other RTKs can rescue and maintain FAK activation (pY397) even in the presence of FAK-kinase inhibition. These data may have important ramifications for existing clinical trials of FAK inhibitors and suggest that individual tumor stratification by RTK expression would be important to predict patient response to FAK-kinase inhibitors. Mol Cancer Ther; 15(12); 3028-39. ©2016 AACR. ©2016 American Association for Cancer Research.

Automated Leaf Tracking using Multi-view Image Sequences of Maize Plants for Leaf-growth Monitoring

Science.gov (United States)

Das Choudhury, S.; Awada, T.; Samal, A.; Stoerger, V.; Bashyam, S.

2017-12-01

Extraction of phenotypes with botanical importance by analyzing plant image sequences has the desirable advantages of non-destructive temporal phenotypic measurements of a large number of plants with little or no manual intervention in a relatively short period of time. The health of a plant is best interpreted by the emergence timing and temporal growth of individual leaves. For automated leaf growth monitoring, it is essential to track each leaf throughout the life cycle of the plant. Plants are constantly changing organisms with increasing complexity in architecture due to variations in self-occlusions and phyllotaxy, i.e., arrangements of leaves around the stem. The leaf cross-overs pose challenges to accurately track each leaf using single view image sequence. Thus, we introduce a novel automated leaf tracking algorithm using a graph theoretic approach by multi-view image sequence analysis based on the determination of leaf-tips and leaf-junctions in the 3D space. The basis of the leaf tracking algorithm is: the leaves emerge using bottom-up approach in the case of a maize plant, and the direction of leaf emergence strictly alternates in terms of direction. The algorithm involves labeling of the individual parts of a plant, i.e., leaves and stem, following graphical representation of the plant skeleton, i.e., one-pixel wide connected line obtained from the binary image. The length of the leaf is measured by the number of pixels in the leaf skeleton. To evaluate the performance of the algorithm, a benchmark dataset is indispensable. Thus, we publicly release University of Nebraska-Lincoln Component Plant Phenotyping dataset-2 (UNL-CPPD-2) consisting of images of the 20 maize plants captured by visible light camera of the Lemnatec Scanalyzer 3D high throughout plant phenotyping facility once daily for 60 days from 10 different views. The dataset is aimed to facilitate the development and evaluation of leaf tracking algorithms and their uniform comparisons.

Metabolism of organic acids, nitrogen and amino acids in chlorotic leaves of 'Honeycrisp' apple (Malus domestica Borkh) with excessive accumulation of carbohydrates.

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Wang, Huicong; Ma, Fangfang; Cheng, Lailiang

2010-07-01

Metabolite profiles and activities of key enzymes in the metabolism of organic acids, nitrogen and amino acids were compared between chlorotic leaves and normal leaves of 'Honeycrisp' apple to understand how accumulation of non-structural carbohydrates affects the metabolism of organic acids, nitrogen and amino acids. Excessive accumulation of non-structural carbohydrates and much lower CO(2) assimilation were found in chlorotic leaves than in normal leaves, confirming feedback inhibition of photosynthesis in chlorotic leaves. Dark respiration and activities of several key enzymes in glycolysis and tricarboxylic acid (TCA) cycle, ATP-phosphofructokinase, pyruvate kinase, citrate synthase, aconitase and isocitrate dehydrogenase were significantly higher in chlorotic leaves than in normal leaves. However, concentrations of most organic acids including phosphoenolpyruvate (PEP), pyruvate, oxaloacetate, 2-oxoglutarate, malate and fumarate, and activities of key enzymes involved in the anapleurotic pathway including PEP carboxylase, NAD-malate dehydrogenase and NAD-malic enzyme were significantly lower in chlorotic leaves than in normal leaves. Concentrations of soluble proteins and most free amino acids were significantly lower in chlorotic leaves than in normal leaves. Activities of key enzymes in nitrogen assimilation and amino acid synthesis, including nitrate reductase, glutamine synthetase, ferredoxin and NADH-dependent glutamate synthase, and glutamate pyruvate transaminase were significantly lower in chlorotic leaves than in normal leaves. It was concluded that, in response to excessive accumulation of non-structural carbohydrates, glycolysis and TCA cycle were up-regulated to "consume" the excess carbon available, whereas the anapleurotic pathway, nitrogen assimilation and amino acid synthesis were down-regulated to reduce the overall rate of amino acid and protein synthesis.

Measurement for the MLC leaf velocity profile by considering the leaf leakage using a radiographic film

International Nuclear Information System (INIS)

Chow, James C L; Grigorov, Grigor N

2006-01-01

A method to measure the velocity profile of a multi-leaf collimator (MLC) leaf along its travel range using a radiographic film is reported by considering the intra-leaf leakage. A specific dynamic MLC field with leaves travelling from the field edge to the isocentre line was designed. The field was used to expose a radiographic film, which was then scanned, and the dose profile along the horizontal leaf axis was measured. The velocity at a sampling point on the film can be calculated by considering the horizontal distance between the sampling point and the isocentre line, dose at the sampling point, dose rate of the linear accelerator, the total leaf travel time from the field edge to isocentre line and the pre-measured dose rate of leaf leakage. With the leaf velocities and velocity profiles for all MLC leaves measured routinely, a comprehensive and simple QA for the MLC can be set up to test the consistency of the leaf velocity performance which is essential to the IMRT delivery using a sliding window technique. (note)

Ribulose 1,5-bisphosphate carboxylase synthesis during heat shock

International Nuclear Information System (INIS)

Vierling, E.; Key, J.L.

1985-01-01

Ribulose 1,5-bisphosphate carboxylase (RuBPCase) was chosen as a model protein to study how heat shock (HS) affects both chloroplast protein synthesis and the nuclear-chloroplast interaction in production of chloroplast proteins. Experiments were performed using highly chlorophyllous, soybean (Glycine max L. Merr. var Corsoy) cell suspension cultures active in chloroplast protein synthesis. Synthesis of RuBPCase large (L) and small (S) subunits was followed by in vivo labeling, and corresponding mRNA levels were examined by Northern and dot hybridization analyses. Results demonstrate that L and S synthesis declines with increasing HS temperatures (33-40 0 C) and reaches minimum levels (20-30% of control) at temperatures of maximum HS protein synthesis (39-40 0 C). Recovery of L and S synthesis following a 2-hour HS at 38 or 40 0 C was also studied. The changes in S synthesis during HS and recovery correlate with the steady state levels of S mRNA. In contrast, changes in L synthesis show little relationship to the corresponding mRNA levels; levels of L mRNA remain relatively unchanged by HS. The authors conclude that chloroplast protein synthesis shows no greater sensitivity to HS than is observed for cytoplasmic protein synthesis and that transport of proteins into the chloroplast (e.g.,S subunit) continues during HS. Furthermore, there is no apparent coordination of L and S subunit mNRA levels under the conditions examined

Geometric leaf placement strategies

International Nuclear Information System (INIS)

Fenwick, J D; Temple, S W P; Clements, R W; Lawrence, G P; Mayles, H M O; Mayles, W P M

2004-01-01

Geometric leaf placement strategies for multileaf collimators (MLCs) typically involve the expansion of the beam's-eye-view contour of a target by a uniform MLC margin, followed by movement of the leaves until some point on each leaf end touches the expanded contour. Film-based dose-distribution measurements have been made to determine appropriate MLC margins-characterized through an index d 90 -for multileaves set using one particular strategy to straight lines lying at various angles to the direction of leaf travel. Simple trigonometric relationships exist between different geometric leaf placement strategies and are used to generalize the results of the film work into d 90 values for several different strategies. Measured d 90 values vary both with angle and leaf placement strategy. A model has been derived that explains and describes quite well the observed variations of d 90 with angle. The d 90 angular variations of the strategies studied differ substantially, and geometric and dosimetric reasoning suggests that the best strategy is the one with the least angular variation. Using this criterion, the best straightforwardly implementable strategy studied is a 'touch circle' approach for which semicircles are imagined to be inscribed within leaf ends, the leaves being moved until the semicircles just touch the expanded target outline

A Role for Mitochondrial Phosphoenolpyruvate Carboxykinase (PEPCK-M) in the Regulation of Hepatic Gluconeogenesis*

Science.gov (United States)

Stark, Romana; Guebre-Egziabher, Fitsum; Zhao, Xiaojian; Feriod, Colleen; Dong, Jianying; Alves, Tiago C.; Ioja, Simona; Pongratz, Rebecca L.; Bhanot, Sanjay; Roden, Michael; Cline, Gary W.; Shulman, Gerald I.; Kibbey, Richard G.

2014-01-01

Synthesis of phosphoenolpyruvate (PEP) from oxaloacetate is an absolute requirement for gluconeogenesis from mitochondrial substrates. Generally, this reaction has solely been attributed to the cytosolic isoform of PEPCK (PEPCK-C), although loss of the mitochondrial isoform (PEPCK-M) has never been assessed. Despite catalyzing the same reaction, to date the only significant role reported in mammals for the mitochondrial isoform is as a glucose sensor necessary for insulin secretion. We hypothesized that this nutrient-sensing mitochondrial GTP-dependent pathway contributes importantly to gluconeogenesis. PEPCK-M was acutely silenced in gluconeogenic tissues of rats using antisense oligonucleotides both in vivo and in isolated hepatocytes. Silencing PEPCK-M lowers plasma glucose, insulin, and triglycerides, reduces white adipose, and depletes hepatic glycogen, but raises lactate. There is a switch of gluconeogenic substrate preference to glycerol that quantitatively accounts for a third of glucose production. In contrast to the severe mitochondrial deficiency characteristic of PEPCK-C knock-out livers, hepatocytes from PEPCK-M-deficient livers maintained normal oxidative function. Consistent with its predicted role, gluconeogenesis rates from hepatocytes lacking PEPCK-M are severely reduced for lactate, alanine, and glutamine, but not for pyruvate and glycerol. Thus, PEPCK-M has a direct role in fasted and fed glucose homeostasis, and this mitochondrial GTP-dependent pathway should be reconsidered for its involvement in both normal and diabetic metabolism. PMID:24497630

A role for mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) in the regulation of hepatic gluconeogenesis.

Science.gov (United States)

Stark, Romana; Guebre-Egziabher, Fitsum; Zhao, Xiaojian; Feriod, Colleen; Dong, Jianying; Alves, Tiago C; Ioja, Simona; Pongratz, Rebecca L; Bhanot, Sanjay; Roden, Michael; Cline, Gary W; Shulman, Gerald I; Kibbey, Richard G

2014-03-14

Synthesis of phosphoenolpyruvate (PEP) from oxaloacetate is an absolute requirement for gluconeogenesis from mitochondrial substrates. Generally, this reaction has solely been attributed to the cytosolic isoform of PEPCK (PEPCK-C), although loss of the mitochondrial isoform (PEPCK-M) has never been assessed. Despite catalyzing the same reaction, to date the only significant role reported in mammals for the mitochondrial isoform is as a glucose sensor necessary for insulin secretion. We hypothesized that this nutrient-sensing mitochondrial GTP-dependent pathway contributes importantly to gluconeogenesis. PEPCK-M was acutely silenced in gluconeogenic tissues of rats using antisense oligonucleotides both in vivo and in isolated hepatocytes. Silencing PEPCK-M lowers plasma glucose, insulin, and triglycerides, reduces white adipose, and depletes hepatic glycogen, but raises lactate. There is a switch of gluconeogenic substrate preference to glycerol that quantitatively accounts for a third of glucose production. In contrast to the severe mitochondrial deficiency characteristic of PEPCK-C knock-out livers, hepatocytes from PEPCK-M-deficient livers maintained normal oxidative function. Consistent with its predicted role, gluconeogenesis rates from hepatocytes lacking PEPCK-M are severely reduced for lactate, alanine, and glutamine, but not for pyruvate and glycerol. Thus, PEPCK-M has a direct role in fasted and fed glucose homeostasis, and this mitochondrial GTP-dependent pathway should be reconsidered for its involvement in both normal and diabetic metabolism.

Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

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de Boer, Hugo; Drake, Paul; Veneklaas, Erik

2017-04-01

The close relationship between leaf water status and stomatal conductance implies that the hydraulic architecture of leaves poses an important constraint on transpiration, specifically in arid environments with high evaporative demands. However, it remains uncertain how morphological, hydraulic and photosynthetic traits are coordinated to achieve optimal leaf functioning in arid environments. Critical is that leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy≈1. Although this theory is supported by observations on many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis we assembled leaf hydraulic, morphological and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent over-investment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf lifespan, high hydraulic and thermal capacitances, and high potential rates of leaf

Understanding the molecular basis of plant growth promotional effect of Pseudomonas fluorescens on rice through protein profiling.

Science.gov (United States)

Kandasamy, Saveetha; Loganathan, Karthiba; Muthuraj, Raveendran; Duraisamy, Saravanakumar; Seetharaman, Suresh; Thiruvengadam, Raguchander; Ponnusamy, Balasubramanian; Ramasamy, Samiyappan

2009-12-24

Plant Growth Promoting Rhizobacteria (PGPR), Pseudomonas fluorescens strain KH-1 was found to exhibit plant growth promotional activity in rice under both in-vitro and in-vivo conditions. But the mechanism underlying such promotional activity of P. fluorescens is not yet understood clearly. In this study, efforts were made to elucidate the molecular responses of rice plants to P. fluorescens treatment through protein profiling. Two-dimensional polyacrylamide gel electrophoresis strategy was adopted to identify the PGPR responsive proteins and the differentially expressed proteins were analyzed by mass spectrometry. Priming of P. fluorescens, 23 different proteins found to be differentially expressed in rice leaf sheaths and MS analysis revealed the differential expression of some important proteins namely putative p23 co-chaperone, Thioredoxin h- rice, Ribulose-bisphosphate carboxylase large chain precursor, Nucleotide diPhosphate kinase, Proteosome sub unit protein and putative glutathione S-transferase protein. Functional analyses of the differential proteins were reported to be directly or indirectly involved in growth promotion in plants. Thus, this study confirms the primary role of PGPR strain KH-1 in rice plant growth promotion.

In vitro antiglioma action of indomethacin is mediated via AMP-activated protein kinase/mTOR complex 1 signalling pathway.

Science.gov (United States)

Pantovic, Aleksandar; Bosnjak, Mihajlo; Arsikin, Katarina; Kosic, Milica; Mandic, Milos; Ristic, Biljana; Tosic, Jelena; Grujicic, Danica; Isakovic, Aleksandra; Micic, Nikola; Trajkovic, Vladimir; Harhaji-Trajkovic, Ljubica

2017-02-01

We investigated the role of the intracellular energy-sensing AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway in the in vitro antiglioma effect of the cyclooxygenase (COX) inhibitor indomethacin. Indomethacin was more potent than COX inhibitors diclofenac, naproxen, and ketoprofen in reducing the viability of U251 human glioma cells. Antiglioma effect of the drug was associated with p21 increase and G 2 M cell cycle arrest, as well as with oxidative stress, mitochondrial depolarization, caspase activation, and the induction of apoptosis. Indomethacin increased the phosphorylation of AMPK and its targets Raptor and acetyl-CoA carboxylase (ACC), and reduced the phosphorylation of mTOR and mTOR complex 1 (mTORC1) substrates p70S6 kinase and PRAS40 (Ser183). AMPK knockdown by RNA interference, as well as the treatment with the mTORC1 activator leucine, prevented indomethacin-mediated mTORC1 inhibition and cytotoxic action, while AMPK activators metformin and AICAR mimicked the effects of the drug. AMPK activation by indomethacin correlated with intracellular ATP depletion and increase in AMP/ATP ratio, and was apparently independent of COX inhibition or the increase in intracellular calcium. Finally, the toxicity of indomethacin towards primary human glioma cells was associated with the activation of AMPK/Raptor/ACC and subsequent suppression of mTORC1/S6K. By demonstrating the involvement of AMPK/mTORC1 pathway in the antiglioma action of indomethacin, our results support its further exploration in glioma therapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Engineering of kinase-based protein interacting devices: active expression of tyrosine kinase domains

KAUST Repository

Diaz Galicia, Miriam Escarlet

2018-05-01

Protein-protein interactions modulate cellular processes in health and disease. However, tracing weak or rare associations or dissociations of proteins is not a trivial task. Kinases are often regulated through interaction partners and, at the same time, themselves regulate cellular interaction networks. The use of kinase domains for creating a synthetic sensor device that reads low concentration protein-protein interactions and amplifies them to a higher concentration interaction which is then translated into a FRET (Fluorescence Resonance Energy Transfer) signal is here proposed. To this end, DNA constructs for interaction amplification (split kinases), positive controls (intact kinase domains), scaffolding proteins and phosphopeptide - SH2-domain modules for the reading of kinase activity were assembled and expression protocols for fusion proteins containing Lyn, Src, and Fak kinase domains in bacterial and in cell-free systems were optimized. Also, two non-overlapping methods for measuring the kinase activity of these proteins were stablished and, finally, a protein-fragment complementation assay with the split-kinase constructs was tested. In conclusion, it has been demonstrated that features such as codon optimization, vector design and expression conditions have an impact on the expression yield and activity of kinase-based proteins. Furthermore, it has been found that the defined PURE cell-free system is insufficient for the active expression of catalytic kinase domains. In contrast, the bacterial co-expression with phosphatases produced active kinase fusion proteins for two out of the three tested Tyrosine kinase domains.

14CO2 fixation and allocation of 14C into major biochemical fractions in different parts of Indian mustard (Brassica juncea)

International Nuclear Information System (INIS)

Subrahmanyam, D.; Rathore, V.S.

1993-01-01

14CO2 fixation and transport of 14C-photosynthates amongst different parts of Indian mustard (Brassica juncea) and the incorporation of 14C into major chemical fractions in different plant parts was studied at ripening stage. Stem and pod together contributed 70 % of the total 14C fixed by the plant. In all plant parts neutral saccharide fraction contained maximum radioactivity immediately after exposing plants to 14CO2. After 24 h, the radioactivity in this fraction declined considerably due to translocation or conversion into other fractions. Concomitantly radioactivity in lipids and pigments, residue and starch fractions increased after 24 h. The 14C allocation patterns in stem and leaves were similar. However, in pods very high radioactivity was recovered from amino and organic acid fractions indicating the presence of active phosphoenolpyruvate carboxylase in pod walls

Novel Mutations in the PC Gene in Patients with Type B Pyruvate Carboxylase Deficiency

DEFF Research Database (Denmark)

Ostergaard, Elsebet; Duno, Morten; Møller, Lisbeth Birk

2013-01-01

We have investigated seven patients with the type B form of pyruvate carboxylase (PC) deficiency. Mutation analysis revealed eight mutations, all novel. In a patient with exon skipping on cDNA analysis, we identified a homozygous mutation located in a potential branch point sequence, the first...... possible branch point mutation in PC. Two patients were homozygous for missense mutations (with normal protein amounts on western blot analysis), and two patients were homozygous for nonsense mutations. In addition, a duplication of one base pair was found in a patient who also harboured a splice site...... mutation. Another splice site mutation led to the activation of a cryptic splice site, shown by cDNA analysis.All patients reported until now with at least one missense mutation have had the milder type A form of PC deficiency. We thus report for the first time two patients with homozygous missense...

NARROW LEAF 7 controls leaf shape mediated by auxin in rice

NARCIS (Netherlands)

Fujino, Kenji; Matsuda, Yasuyuki; Ozawa, Kenjirou; Nishimura, Takeshi; Koshiba, Tomokazu; Fraaije, Marco W.; Sekiguchi, Hiroshi

Elucidation of the genetic basis of the control of leaf shape could be of use in the manipulation of crop traits, leading to more stable and increased crop production. To improve our understanding of the process controlling leaf shape, we identified a mutant gene in rice that causes a significant

Body weight management effect of burdock (Arctium lappa L.) root is associated with the activation of AMP-activated protein kinase in human HepG2 cells.

Science.gov (United States)

Kuo, Daih-Huang; Hung, Ming-Chi; Hung, Chao-Ming; Liu, Li-Min; Chen, Fu-An; Shieh, Po-Chuen; Ho, Chi-Tang; Way, Tzong-Der

2012-10-01

Burdock (Arcticum lappa L.) root is used in folk medicine and also as a vegetable in Asian countries. In the present study, burdock root treatment significantly reduced body weight in rats. To evaluate the bioactive compounds, we successively extracted the burdock root with ethanol (AL-1), and fractionated it with n-hexane (AL-2), ethyl acetate (AL-3), n-butanol (AL-4), and water (AL-5). Among these fractions, AL-2 contained components with the most effective hypolipidemic potential in human hepatoma HepG2 cells. AL-2 decreased the expression of fatty acid synthase (FASN) and inhibited the activity of acetyl-coenzyme A carboxylase (ACC) by stimulating AMP-activated protein kinase (AMPK) through the LKB1 pathway. Three active compounds were identified from the AL-2, namely α-linolenic acid, methyl α-linolenate, and methyl oleate. These results suggest that burdock root is expected to be useful for body weight management. Copyright © 2012 Elsevier Ltd. All rights reserved.

Influence of age on leptin induced skeletal muscle signaling

DEFF Research Database (Denmark)

Guadalupe Grau, Amelia; Larsen, Steen; Guerra, Borja

2014-01-01

transducer and activator of transcription 3 (STAT3), insulin receptor substrate 1 (IRS-1), AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC), combined with the leptin signaling inhibitors suppressor of cytokine signaling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) in human...

Survey of tyrosine kinase signaling reveals ROS kinase fusions in human cholangiocarcinoma.

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Ting-Lei Gu

Full Text Available Cholangiocarcinoma, also known as bile duct cancer, is the second most common primary hepatic carcinoma with a median survival of less than 2 years. The molecular mechanisms underlying the development of this disease are not clear. To survey activated tyrosine kinases signaling in cholangiocarcinoma, we employed immunoaffinity profiling coupled to mass spectrometry and identified DDR1, EPHA2, EGFR, and ROS tyrosine kinases, along with over 1,000 tyrosine phosphorylation sites from about 750 different proteins in primary cholangiocarcinoma patients. Furthermore, we confirmed the presence of ROS kinase fusions in 8.7% (2 out of 23 of cholangiocarcinoma patients. Expression of the ROS fusions in 3T3 cells confers transforming ability both in vitro and in vivo, and is responsive to its kinase inhibitor. Our data demonstrate that ROS kinase is a promising candidate for a therapeutic target and for a diagnostic molecular marker in cholangiocarcinoma. The identification of ROS tyrosine kinase fusions in cholangiocarcinoma, along with the presence of other ROS kinase fusions in lung cancer and glioblastoma, suggests that a more broadly based screen for activated ROS kinase in cancer is warranted.

The Crystal Structure of Toxoplasma gondii Pyruvate Kinase 1

Energy Technology Data Exchange (ETDEWEB)

Bakszt, R.; Wernimont, A; Allali-Hassani, A; Mok, M; Hills, T; Hui, R; Pizarro, J

2010-01-01

Pyruvate kinase (PK), which catalyzes the final step in glycolysis converting phosphoenolpyruvate to pyruvate, is a central metabolic regulator in most organisms. Consequently PK represents an attractive therapeutic target in cancer and human pathogens, like Apicomplexans. The phylum Aplicomplexa, a group of exclusively parasitic organisms, includes the genera Plasmodium, Cryptosporidium and Toxoplasma, the etiological agents of malaria, cryptosporidiosis and toxoplasmosis respectively. Toxoplasma gondii infection causes a mild illness and is a very common infection affecting nearly one third of the world's population. We have determined the crystal structure of the PK1 enzyme from T. gondii, with the B domain in the open and closed conformations. We have also characterized its enzymatic activity and confirmed glucose-6-phosphate as its allosteric activator. This is the first description of a PK enzyme in a closed inactive conformation without any bound substrate. Comparison of the two tetrameric TgPK1 structures indicates a reorientation of the monomers with a concomitant change in the buried surface among adjacent monomers. The change in the buried surface was associated with significant B domain movements in one of the interacting monomers. We hypothesize that a loop in the interface between the A and B domains plays an important role linking the position of the B domain to the buried surface among monomers through two {alpha}-helices. The proposed model links the catalytic cycle of the enzyme with its domain movements and highlights the contribution of the interface between adjacent subunits. In addition, an unusual ordered conformation was observed in one of the allosteric binding domains and it is related to a specific apicomplexan insertion. The sequence and structural particularity would explain the atypical activation by a mono-phosphorylated sugar. The sum of peculiarities raises this enzyme as an emerging target for drug discovery.

The crystal structure of Toxoplasma gondii pyruvate kinase 1.

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Rebecca Bakszt

2010-09-01

Full Text Available Pyruvate kinase (PK, which catalyzes the final step in glycolysis converting phosphoenolpyruvate to pyruvate, is a central metabolic regulator in most organisms. Consequently PK represents an attractive therapeutic target in cancer and human pathogens, like Apicomplexans. The phylum Aplicomplexa, a group of exclusively parasitic organisms, includes the genera Plasmodium, Cryptosporidium and Toxoplasma, the etiological agents of malaria, cryptosporidiosis and toxoplasmosis respectively. Toxoplasma gondii infection causes a mild illness and is a very common infection affecting nearly one third of the world's population.We have determined the crystal structure of the PK1 enzyme from T. gondii, with the B domain in the open and closed conformations. We have also characterized its enzymatic activity and confirmed glucose-6-phosphate as its allosteric activator. This is the first description of a PK enzyme in a closed inactive conformation without any bound substrate. Comparison of the two tetrameric TgPK1 structures indicates a reorientation of the monomers with a concomitant change in the buried surface among adjacent monomers. The change in the buried surface was associated with significant B domain movements in one of the interacting monomers.We hypothesize that a loop in the interface between the A and B domains plays an important role linking the position of the B domain to the buried surface among monomers through two α-helices. The proposed model links the catalytic cycle of the enzyme with its domain movements and highlights the contribution of the interface between adjacent subunits. In addition, an unusual ordered conformation was observed in one of the allosteric binding domains and it is related to a specific apicomplexan insertion. The sequence and structural particularity would explain the atypical activation by a mono-phosphorylated sugar. The sum of peculiarities raises this enzyme as an emerging target for drug discovery.

The crystal structure of Toxoplasma gondii pyruvate kinase 1.

Science.gov (United States)

Bakszt, Rebecca; Wernimont, Amy; Allali-Hassani, Abdellah; Mok, Man Wai; Hills, Tanya; Hui, Raymond; Pizarro, Juan C

2010-09-14

Pyruvate kinase (PK), which catalyzes the final step in glycolysis converting phosphoenolpyruvate to pyruvate, is a central metabolic regulator in most organisms. Consequently PK represents an attractive therapeutic target in cancer and human pathogens, like Apicomplexans. The phylum Aplicomplexa, a group of exclusively parasitic organisms, includes the genera Plasmodium, Cryptosporidium and Toxoplasma, the etiological agents of malaria, cryptosporidiosis and toxoplasmosis respectively. Toxoplasma gondii infection causes a mild illness and is a very common infection affecting nearly one third of the world's population. We have determined the crystal structure of the PK1 enzyme from T. gondii, with the B domain in the open and closed conformations. We have also characterized its enzymatic activity and confirmed glucose-6-phosphate as its allosteric activator. This is the first description of a PK enzyme in a closed inactive conformation without any bound substrate. Comparison of the two tetrameric TgPK1 structures indicates a reorientation of the monomers with a concomitant change in the buried surface among adjacent monomers. The change in the buried surface was associated with significant B domain movements in one of the interacting monomers. We hypothesize that a loop in the interface between the A and B domains plays an important role linking the position of the B domain to the buried surface among monomers through two α-helices. The proposed model links the catalytic cycle of the enzyme with its domain movements and highlights the contribution of the interface between adjacent subunits. In addition, an unusual ordered conformation was observed in one of the allosteric binding domains and it is related to a specific apicomplexan insertion. The sequence and structural particularity would explain the atypical activation by a mono-phosphorylated sugar. The sum of peculiarities raises this enzyme as an emerging target for drug discovery.

Scaling up stomatal conductance from leaf to canopy using a dual-leaf model for estimating crop evapotranspiration.

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Risheng Ding

Full Text Available The dual-source Shuttleworth-Wallace model has been widely used to estimate and partition crop evapotranspiration (λET. Canopy stomatal conductance (Gsc, an essential parameter of the model, is often calculated by scaling up leaf stomatal conductance, considering the canopy as one single leaf in a so-called "big-leaf" model. However, Gsc can be overestimated or underestimated depending on leaf area index level in the big-leaf model, due to a non-linear stomatal response to light. A dual-leaf model, scaling up Gsc from leaf to canopy, was developed in this study. The non-linear stomata-light relationship was incorporated by dividing the canopy into sunlit and shaded fractions and calculating each fraction separately according to absorbed irradiances. The model includes: (1 the absorbed irradiance, determined by separately integrating the sunlit and shaded leaves with consideration of both beam and diffuse radiation; (2 leaf area for the sunlit and shaded fractions; and (3 a leaf conductance model that accounts for the response of stomata to PAR, vapor pressure deficit and available soil water. In contrast to the significant errors of Gsc in the big-leaf model, the predicted Gsc using the dual-leaf model had a high degree of data-model agreement; the slope of the linear regression between daytime predictions and measurements was 1.01 (R2 = 0.98, with RMSE of 0.6120 mm s-1 for four clear-sky days in different growth stages. The estimates of half-hourly λET using the dual-source dual-leaf model (DSDL agreed well with measurements and the error was within 5% during two growing seasons of maize with differing hydrometeorological and management strategies. Moreover, the estimates of soil evaporation using the DSDL model closely matched actual measurements. Our results indicate that the DSDL model can produce more accurate estimation of Gsc and λET, compared to the big-leaf model, and thus is an effective alternative approach for estimating and

Seasonality of Leaf Carbon Isotopic Composition and Leaf Water Isotopic Enrichment in a Mixed Evergreen Forest in Southern California

Science.gov (United States)

Santiago, L. S.; Sickman, J. O.; Goulden, M.; DeVan, C.; Pasquini, S. C.; Pivovaroff, A. L.

2011-12-01

Leaf carbon isotopic composition and leaf water isotopic enrichment reflect physiological processes and are important for linking local and regional scale processes to global patterns. We investigated how seasonality affects the isotopic composition of bulk leaf carbon, leaf sugar carbon, and leaf water hydrogen under a Mediterranean climate. Leaf and stem samples were collected monthly from four tree species (Calocedrus decurrens, Pinus lambertiana, Pinus ponderosa, and Quercus chrysolepis) at the James San Jacinto Mountain Reserve in southern California. Mean monthly bulk leaf carbon isotopic composition varied from -34.5 % in P. ponderosa to -24.7 % in P. lambertiana and became more depleted in 13C from the spring to the summer. Mean monthly leaf sugar varied from -29.3 % in P. ponderosa to -21.8 % in P. lambertiana and was enriched in 13C during the winter, spring and autumn, but depleted during the mid-summer. Leaf water hydrogen isotopic composition was 28.4 to 68.8 % more enriched in deuterium than source water and this enrichment was greater as seasonal drought progressed. These data indicate that leaf carbon and leaf water hydrogen isotopic composition provide sensitive measures that connect plant physiological processes to short-term climatic variability.

A proteomic approach for comprehensively screening substrates of protein kinases such as Rho-kinase.

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Mutsuki Amano

Full Text Available BACKGROUND: Protein kinases are major components of signal transduction pathways in multiple cellular processes. Kinases directly interact with and phosphorylate downstream substrates, thus modulating their functions. Despite the importance of identifying substrates in order to more fully understand the signaling network of respective kinases, efficient methods to search for substrates remain poorly explored. METHODOLOGY/PRINCIPAL FINDINGS: We combined mass spectrometry and affinity column chromatography of the catalytic domain of protein kinases to screen potential substrates. Using the active catalytic fragment of Rho-kinase/ROCK/ROK as the model bait, we obtained about 300 interacting proteins from the rat brain cytosol fraction, which included the proteins previously reported as Rho-kinase substrates. Several novel interacting proteins, including doublecortin, were phosphorylated by Rho-kinase both in vitro and in vivo. CONCLUSIONS/SIGNIFICANCE: This method would enable identification of novel specific substrates for kinases such as Rho-kinase with high sensitivity.

Biotin increases glucokinase expression via soluble guanylate cyclase/protein kinase G, adenosine triphosphate production and autocrine action of insulin in pancreatic rat islets.

Science.gov (United States)

Vilches-Flores, Alonso; Tovar, Armando R; Marin-Hernandez, Alvaro; Rojas-Ochoa, Alberto; Fernandez-Mejia, Cristina

2010-07-01

Besides its role as a carboxylase prosthetic group, biotin has important effects on gene expression. However, the molecular mechanisms through which biotin exerts these effects are largely unknown. We previously found that biotin increases pancreatic glucokinase expression. We have now explored the mechanisms underlying this effect. Pancreatic islets from Wistar rats were treated with biotin, in the presence or absence of different types of inhibitors. Glucokinase mRNA and 18s rRNA abundance were determined by real-time PCR. Adenosine triphosphate (ATP) content was analyzed by fluorometry. Biotin treatment increased glucokinase mRNA abundance approximately one fold after 2 h; the effect was sustained up to 24 h. Inhibition of soluble guanylate cyclase or protein kinase G (PKG) signalling suppressed biotin-induced glucokinase expression. The cascade of events downstream of PKG in biotin-mediated gene transcription is not known. We found that inhibition of insulin secretion with diazoxide or nifedipine prevented biotin-stimulated glucokinase mRNA increase. Biotin treatment increased islet ATP content (control: 4.68+/-0.28; biotin treated: 6.62+/-0.26 pmol/islet) at 30 min. Inhibition of PKG activity suppressed the effects of biotin on ATP content. Insulin antibodies or inhibitors of phosphoinositol-3-kinase/Akt insulin signalling pathway prevented biotin-induced glucokinase expression. The nucleotide 8-Br-cGMP mimicked the biotin effects. We propose that the induction of pancreatic glucokinase mRNA by biotin involves guanylate cyclase and PKG activation, which leads to an increase in ATP content. This induces insulin secretion via ATP-sensitive potassium channels. Autocrine insulin, in turn, activates phosphoinositol-3-kinase/Akt signalling. Our results offer new insights into the pathways that participate in biotin-mediated gene expression. (c) 2010 Elsevier Inc. All rights reserved.

Site-directed mutagenesis of serine 158 demonstrates its role in spinach leaf sucrose-phosphate synthase modulation

Science.gov (United States)

Toroser, D.; McMichael, R. Jr; Krause, K. P.; Kurreck, J.; Sonnewald, U.; Stitt, M.; Huber, S. C.; Davies, E. (Principal Investigator)

1999-01-01

Site-directed mutagenesis of spinach sucrose-phosphate synthase (SPS) was performed to investigate the role of Ser158 in the modulation of spinach leaf SPS. Tobacco plants expressing the spinach wild-type (WT), S158A, S158T and S157F/S158E SPS transgenes were produced. Expression of transgenes appeared not to reduce expression of the tobacco host SPS. SPS activity in the WT and the S158T SPS transgenics showed light/dark modulation, whereas the S158A and S157F/S158E mutants were not similarly light/dark modulated: the S158A mutant enzyme was not inactivated in the dark, and the S157F/S158E was not activated in the light. The inability to modulate the activity of the S158A mutant enzyme by protein phosphorylation was demonstrated in vitro. The WT spinach enzyme immunopurified from dark transgenic tobacco leaves had a low initial activation state, and could be activated by PP2A and subsequently inactivated by SPS-kinase plus ATP. Rapid purification of the S158A mutant enzyme from dark leaves of transgenic plants using spinach-specific monoclonal antibodies yielded enzyme that had a high initial activation state, and pre-incubation with leaf PP2A or ATP plus SPS-kinase (the PKIII enzyme) caused little modulation of activity. The results demonstrate the regulatory significance of Ser158 as the major site responsible for dark inactivation of spinach SPS in vivo, and indicate that the significance of phosphorylation is the introduction of a negative charge at the Ser158 position.

Leaf sequencing algorithms for segmented multileaf collimation

International Nuclear Information System (INIS)

Kamath, Srijit; Sahni, Sartaj; Li, Jonathan; Palta, Jatinder; Ranka, Sanjay

2003-01-01

The delivery of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) requires the conversion of a radiation fluence map into a leaf sequence file that controls the movement of the MLC during radiation delivery. It is imperative that the fluence map delivered using the leaf sequence file is as close as possible to the fluence map generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. Optimization of the leaf sequencing algorithm has been the subject of several recent investigations. In this work, we present a systematic study of the optimization of leaf sequencing algorithms for segmental multileaf collimator beam delivery and provide rigorous mathematical proofs of optimized leaf sequence settings in terms of monitor unit (MU) efficiency under most common leaf movement constraints that include minimum leaf separation constraint and leaf interdigitation constraint. Our analytical analysis shows that leaf sequencing based on unidirectional movement of the MLC leaves is as MU efficient as bidirectional movement of the MLC leaves

Leaf sequencing algorithms for segmented multileaf collimation

Energy Technology Data Exchange (ETDEWEB)

Kamath, Srijit [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Sahni, Sartaj [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Li, Jonathan [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Palta, Jatinder [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Ranka, Sanjay [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States)

2003-02-07

The delivery of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) requires the conversion of a radiation fluence map into a leaf sequence file that controls the movement of the MLC during radiation delivery. It is imperative that the fluence map delivered using the leaf sequence file is as close as possible to the fluence map generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. Optimization of the leaf sequencing algorithm has been the subject of several recent investigations. In this work, we present a systematic study of the optimization of leaf sequencing algorithms for segmental multileaf collimator beam delivery and provide rigorous mathematical proofs of optimized leaf sequence settings in terms of monitor unit (MU) efficiency under most common leaf movement constraints that include minimum leaf separation constraint and leaf interdigitation constraint. Our analytical analysis shows that leaf sequencing based on unidirectional movement of the MLC leaves is as MU efficient as bidirectional movement of the MLC leaves.

Enzyme II/sup Mtl/ of the Escherichia coli phosphoenolpyruvate-dependent phosphotransferase system: identification of the activity-linked cysteine on the mannitol carrier

International Nuclear Information System (INIS)

Pas, H.H.; Robillard, G.T.

1988-01-01

The cysteine of the membrane-bound mannitol-specific enzyme II (EII/sup Mtl/) of the Escherichia coli phosphoenolpyruvate-dependent phosphotransferase system have been labeled with 4-vinylpyridine. After proteolytic breakdown and reversed-phase HPLC, the peptides containing cysteines 110, 384, and 571 could be identified. N-Ethylmaleimide (NEM) treatment of the native unphosphorylated enzyme results in incorporation of one NEM label per molecule and loss of enzymatic activity. NEM treatment and inactivation prevented 4-vinylpyridine incorporation into the Cys-384-containing peptide, identifying this residue as the activity-linked cysteine. Both oxidation and phosphorylation of the native enzyme protected the enzyme against NEM labeling of Cys-384. Positive identification of the activity-linked cysteine was accomplished by inactivation with [ 14 C]iodoacetamide, proteolytic fragmentation, isolation of the peptide, and amino acid sequencing

Study on creation of an indocalamus leaf flavor

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Guangyong ZHU

2015-01-01

Full Text Available AbstractFlavors represent a small but significant segment of food industry. Sensory characteristics play an important role in the process of consumer acceptance and preference. Indocalamus leaf takes on a pleasant odor and indocalamus leaf flavor can be used in many products. However, indocalamus leaf flavor formula has not been reported. Therefore, developing an indocalamus leaf flavor is of significant interests. Note is a distinct flavor or odor characteristic. This paper concentrates on preparation and creation of indocalamus leaf flavor according to the notes of indocalamus leaf. The notes were obtained by smelling indocalamus leaf, and the results showed that the notes of indocalamus leaf flavor can be classified as: green-leafy note, sweet note, beany note, aldehydic note, waxy note, woody note, roast note, creamy note, and nutty note. According to the notes of indocalamus leaf odor, a typical indocalamus leaf flavor formula was obtained. The indocalamus leaf flavor blended is pleasant, harmonious, and has characteristics of indocalamus leaf odor.

Comparative transcriptome profiling of a resistant vs. susceptible tomato (Solanum lycopersicum cultivar in response to infection by tomato yellow leaf curl virus.

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Tianzi Chen

Full Text Available Tomato yellow leaf curl virus (TYLCV threatens tomato production worldwide by causing leaf yellowing, leaf curling, plant stunting and flower abscission. The current understanding of the host plant defense response to this virus is very limited. Using whole transcriptome sequencing, we analyzed the differential gene expression in response to TYLCV infection in the TYLCV-resistant tomato breeding line CLN2777A (R and TYLCV-susceptible tomato breeding line TMXA48-4-0 (S. The mixed inoculated samples from 3, 5 and 7 day post inoculation (dpi were compared to non-inoculated samples at 0 dpi. Of the total of 34831 mapped transcripts, 209 and 809 genes were differentially expressed in the R and S tomato line, respectively. The proportion of up-regulated differentially expressed genes (DEGs in the R tomato line (58.37% was higher than that in the S line (9.17%. Gene ontology (GO analyses revealed that similar GO terms existed in both DEGs of R and S lines; however, some sets of defense related genes and their expression levels were not similar between the two tomato lines. Genes encoding for WRKY transcriptional factors, R genes, protein kinases and receptor (-like kinases which were identified as down-regulated DEGs in the S line were up-regulated or not differentially expressed in the R line. The up-regulated DEGs in the R tomato line revealed the defense response of tomato to TYLCV infection was characterized by the induction and regulation of a series of genes involved in cell wall reorganization, transcriptional regulation, defense response, ubiquitination, metabolite synthesis and so on. The present study provides insights into various reactions underlining the successful establishment of resistance to TYLCV in the R tomato line, and helps in the identification of important defense-related genes in tomato for TYLCV disease management.

Pyruvate carboxylase deficiency: An underestimated cause of lactic acidosis

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F. Habarou

2015-03-01

Full Text Available Pyruvate carboxylase (PC is a biotin-containing mitochondrial enzyme that catalyzes the conversion of pyruvate to oxaloacetate, thereby being involved in gluconeogenesis and in energy production through replenishment of the tricarboxylic acid (TCA cycle with oxaloacetate. PC deficiency is a very rare metabolic disorder. We report on a new patient affected by the moderate form (the American type A. Diagnosis was nearly fortuitous, resulting from the revision of an initial diagnosis of mitochondrial complex IV (C IV defect. The patient presented with severe lactic acidosis and pronounced ketonuria, associated with lethargy at age 23 months. Intellectual disability was noted at this time. Amino acids in plasma and organic acids in urine did not show patterns of interest for the diagnostic work-up. In skin fibroblasts PC showed no detectable activity whereas biotinidase activity was normal. We had previously reported another patient with the severe form of PC deficiency and we show that she also had secondary C IV deficiency in fibroblasts. Different anaplerotic treatments in vivo and in vitro were tested using fibroblasts of both patients with 2 different types of PC deficiency, type A (patient 1 and type B (patient 2. Neither clinical nor biological effects in vivo and in vitro were observed using citrate, aspartate, oxoglutarate and bezafibrate. In conclusion, this case report suggests that the moderate form of PC deficiency may be underdiagnosed and illustrates the challenges raised by energetic disorders in terms of diagnostic work-up and therapeutical strategy even in a moderate form.

The dosimetric impact of leaf interdigitation and leaf width on VMAT treatment planning in Pinnacle: comparing Pareto fronts

International Nuclear Information System (INIS)

Van Kesteren, Z; Janssen, T M; Damen, E; Van Vliet-Vroegindeweij, C

2012-01-01

To evaluate in an objective way the effect of leaf interdigitation and leaf width on volumetric modulated arc therapy plans in Pinnacle. Three multileaf collimators (MLCs) were modeled: two 10 mm leaf width MLCs, with and without interdigitating leafs, and a 5 mm leaf width MLC with interdigitating leafs. Three rectum patients and three prostate patients were used for the planning study. In order to compare treatment techniques in an objective way, a Pareto front comparison was carried out. 200 plans were generated in an automated way, per patient per MLC model, resulting in a total of 3600 plans. From these plans, Pareto-optimal plans were selected which were evaluated for various dosimetric variables. The capability of leaf interdigitation showed little dosimetric impact on the treatment plans, when comparing the 10 mm leaf width MLC with and without leaf interdigitation. When comparing the 10 mm leaf width MLC with the 5 mm leaf width MLC, both with interdigitating leafs, improvement in plan quality was observed. For both patient groups, the integral dose was reduced by 0.6 J for the thin MLC. For the prostate patients, the mean dose to the anal sphincter was reduced by 1.8 Gy and the conformity of the V 95% was reduced by 0.02 using the thin MLC. The V 65% of the rectum was reduced by 0.1% and the dose homogeneity with 1.5%. For rectum patients, the mean dose to the bowel was reduced by 1.4 Gy and the mean dose to the bladder with 0.8 Gy for the thin MLC. The conformity of the V 95% was equivalent for the 10 and 5 mm leaf width MLCs for the rectum patients. We have objectively compared three types of MLCs in a planning study for prostate and rectum patients by analyzing Pareto-optimal plans which were generated in an automated way. Interdigitation of MLC leafs does not generate better plans using the SmartArc algorithm in Pinnacle. Changing the MLC leaf width from 10 to 5 mm generates better treatment plans although the clinical relevance remains to be proven

The dosimetric impact of leaf interdigitation and leaf width on VMAT treatment planning in Pinnacle: comparing Pareto fronts.

Science.gov (United States)

van Kesteren, Z; Janssen, T M; Damen, E; van Vliet-Vroegindeweij, C

2012-05-21

To evaluate in an objective way the effect of leaf interdigitation and leaf width on volumetric modulated arc therapy plans in Pinnacle. Three multileaf collimators (MLCs) were modeled: two 10 mm leaf width MLCs, with and without interdigitating leafs, and a 5 mm leaf width MLC with interdigitating leafs. Three rectum patients and three prostate patients were used for the planning study. In order to compare treatment techniques in an objective way, a Pareto front comparison was carried out. 200 plans were generated in an automated way, per patient per MLC model, resulting in a total of 3600 plans. From these plans, Pareto-optimal plans were selected which were evaluated for various dosimetric variables. The capability of leaf interdigitation showed little dosimetric impact on the treatment plans, when comparing the 10 mm leaf width MLC with and without leaf interdigitation. When comparing the 10 mm leaf width MLC with the 5 mm leaf width MLC, both with interdigitating leafs, improvement in plan quality was observed. For both patient groups, the integral dose was reduced by 0.6 J for the thin MLC. For the prostate patients, the mean dose to the anal sphincter was reduced by 1.8 Gy and the conformity of the V(95%) was reduced by 0.02 using the thin MLC. The V(65%) of the rectum was reduced by 0.1% and the dose homogeneity with 1.5%. For rectum patients, the mean dose to the bowel was reduced by 1.4 Gy and the mean dose to the bladder with 0.8 Gy for the thin MLC. The conformity of the V(95%) was equivalent for the 10 and 5 mm leaf width MLCs for the rectum patients. We have objectively compared three types of MLCs in a planning study for prostate and rectum patients by analyzing Pareto-optimal plans which were generated in an automated way. Interdigitation of MLC leafs does not generate better plans using the SmartArc algorithm in Pinnacle. Changing the MLC leaf width from 10 to 5 mm generates better treatment plans although the clinical relevance remains

Acclimation of photosynthesis, H2O2 content and antioxidants in maiza(Zea mays) grown at sub-optimal temperatures.

NARCIS (Netherlands)

Kingston-Smith, A.H.; Harbinson, J.; Foyer, C.H.

1999-01-01

Maize plants were grown at 14, 18 and 20 °C until the fourth leaf had emerged. Leaves from plants grown at 14 and 18 °C had less chlorophyll than those grown at 20 °C. Maximal extractable ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity was decreased at 14 °C compared with 20 °C,

DIFFERENCES IN LEAF GAS EXCHANGE AND LEAF CHARACTERISTICS BETWEEN TWO ALMOND CULTIVARS

Directory of Open Access Journals (Sweden)

George D. Nanos

2013-12-01

Full Text Available Leaf chlorophyll content, specific leaf weight (SLW, photosynthetic and transpiration rates, stomatal functioning, water use efficiency and quantum yield were assessed during the kernel filling period for two consecutive years in order to understand tissue-centered physiological profile differences between two commercial almond cultivars, ‘Ferragnès’ and ‘Texas’. Similar SLWs were observed on the studied cultivars; however, chlorophyll content, net photosynthetic and transpiration rates and stomatal functioning demonstrated statistically significant differences. In both cultivars, an overall decline in the examined parameters towards fruit maturation (i.e. end of the summer was recorded. ‘Ferragnès’ leaves were found to be more efficient in leaf photosynthesis related performance during kernel filling, when irrigated sufficiently, in comparison to ‘Texas’ leaves. Low average values of leaf conductance during summer in ‘Texas’ leaves revealed its potential for adaptation in cool climates and increased carbon assimilation therein for high kernel yield.

Bacterial Protein-Tyrosine Kinases

DEFF Research Database (Denmark)

Shi, Lei; Kobir, Ahasanul; Jers, Carsten

2010-01-01

in exopolysaccharide production, virulence, DNA metabolism, stress response and other key functions of the bacterial cell. BY-kinases act through autophosphorylation (mainly in exopolysaccharide production) and phosphorylation of other proteins, which have in most cases been shown to be activated by tyrosine......Bacteria and Eukarya share essentially the same family of protein-serine/threonine kinases, also known as the Hanks-type kinases. However, when it comes to protein-tyrosine phosphorylation, bacteria seem to have gone their own way. Bacterial protein-tyrosine kinases (BY-kinases) are bacterial...... and highlighted their importance in bacterial physiology. Having no orthologues in Eukarya, BY-kinases are receiving a growing attention from the biomedical field, since they represent a particularly promising target for anti-bacterial drug design....

Estimating leaf functional traits by inversion of PROSPECT: Assessing leaf dry matter content and specific leaf area in mixed mountainous forest

Science.gov (United States)

Ali, Abebe Mohammed; Darvishzadeh, Roshanak; Skidmore, Andrew K.; Duren, Iris van; Heiden, Uta; Heurich, Marco

2016-03-01

Assessments of ecosystem functioning rely heavily on quantification of vegetation properties. The search is on for methods that produce reliable and accurate baseline information on plant functional traits. In this study, the inversion of the PROSPECT radiative transfer model was used to estimate two functional leaf traits: leaf dry matter content (LDMC) and specific leaf area (SLA). Inversion of PROSPECT usually aims at quantifying its direct input parameters. This is the first time the technique has been used to indirectly model LDMC and SLA. Biophysical parameters of 137 leaf samples were measured in July 2013 in the Bavarian Forest National Park, Germany. Spectra of the leaf samples were measured using an ASD FieldSpec3 equipped with an integrating sphere. PROSPECT was inverted using a look-up table (LUT) approach. The LUTs were generated with and without using prior information. The effect of incorporating prior information on the retrieval accuracy was studied before and after stratifying the samples into broadleaf and conifer categories. The estimated values were evaluated using R2 and normalized root mean square error (nRMSE). Among the retrieved variables the lowest nRMSE (0.0899) was observed for LDMC. For both traits higher R2 values (0.83 for LDMC and 0.89 for SLA) were discovered in the pooled samples. The use of prior information improved accuracy of the retrieved traits. The strong correlation between the estimated traits and the NIR/SWIR region of the electromagnetic spectrum suggests that these leaf traits could be assessed at canopy level by using remotely sensed data.

Spectral reflectance relationships to leaf water stress

Science.gov (United States)

Ripple, William J.

1986-01-01

Spectral reflectance data were collected from detached snapbean leaves in the laboratory with a multiband radiometer. Four experiments were designed to study the spectral response resulting from changes in leaf cover, relative water content of leaves, and leaf water potential. Spectral regions included in the analysis were red (630-690 nm), NIR (760-900 nm), and mid-IR (2.08-2.35 microns). The red and mid-IR bands showed sensitivity to changes in both leaf cover and relative water content of leaves. The NIR was only highly sensitive to changes in leaf cover. Results provided evidence that mid-IR reflectance was governed primarily by leaf moisture content, although soil reflectance was an important factor when leaf cover was less than 100 percent. High correlations between leaf water potentials and reflectance were attributed to covariances with relative water content of leaves and leaf cover.

Comparison of leaf-on and leaf-off ALS data for mapping riparian tree species

Science.gov (United States)

Laslier, Marianne; Ba, Antoine; Hubert-Moy, Laurence; Dufour, Simon

2017-10-01

Forest species composition is a fundamental indicator of forest study and management. However, describing forest species composition at large scales and of highly diverse populations remains an issue for which remote sensing can provide significant contribution, in particular, Airborne Laser Scanning (ALS) data. Riparian corridors are good examples of highly valuable ecosystems, with high species richness and large surface areas that can be time consuming and expensive to monitor with in situ measurements. Remote sensing could be useful to study them, but few studies have focused on monitoring riparian tree species using ALS data. This study aimed to determine which metrics derived from ALS data are best suited to identify and map riparian tree species. We acquired very high density leaf-on and leaf-off ALS data along the Sélune River (France). In addition, we inventoried eight main riparian deciduous tree species along the study site. After manual segmentation of the inventoried trees, we extracted 68 morphological and structural metrics from both leaf-on and leaf-off ALS point clouds. Some of these metrics were then selected using Sequential Forward Selection (SFS) algorithm. Support Vector Machine (SVM) classification results showed good accuracy with 7 metrics (0.77). Both leaf-on and leafoff metrics were kept as important metrics for distinguishing tree species. Results demonstrate the ability of 3D information derived from high density ALS data to identify riparian tree species using external and internal structural metrics. They also highlight the complementarity of leaf-on and leaf-off Lidar data for distinguishing riparian tree species.

Acetyl-CoA carboxylase-a as a novel target for cancer therapy.

Science.gov (United States)

Wang, Chun; Rajput, Sandeep; Watabe, Kounosuke; Liao, Duan-Fang; Cao, Deliang

2010-01-01

Acetyl-CoA carboxylases (ACC) are rate-limiting enzymes in de novo fatty acid synthesis, catalyzing ATP-dependent carboxylation of acetyl-CoA to form malonyl-CoA. Malonyl-CoA is a critical bi-functional molecule, i.e., a substrate of fatty acid synthase (FAS) for acyl chain elongation (fatty acid synthesis) and an inhibitor of carnitine palmitoyltransferase I (CPT-I) for fatty acid beta-oxidation. Two ACC isoforms have been identified in mammals, i.e. ACC-alpha (ACCA, also termed ACC1) and ACC-beta (ACCB, also designated ACC2). ACC has long been used as a target for the management of metabolic diseases, such as obesity and metabolic syndrome, and various inhibitors have been developed in clinical trials. Recently, ACCA up-regulation has been recognized in multiple human cancers, promoting lipogenesis to meet the need of cancer cells for rapid growth and proliferation. Therefore, ACCA might be effective as a potent target for cancer intervention, and the inhibitors developed for the treatment of metabolic diseases would be potential therapeutic agents for cancer therapy. This review summarizes our recent findings and updates the current understanding of the ACCA with focus on cancer research.

Protein kinase activity of phosphoinositide 3-kinase regulates cytokine-dependent cell survival.

Directory of Open Access Journals (Sweden)

Daniel Thomas

Full Text Available The dual specificity protein/lipid kinase, phosphoinositide 3-kinase (PI3K, promotes growth factor-mediated cell survival and is frequently deregulated in cancer. However, in contrast to canonical lipid-kinase functions, the role of PI3K protein kinase activity in regulating cell survival is unknown. We have employed a novel approach to purify and pharmacologically profile protein kinases from primary human acute myeloid leukemia (AML cells that phosphorylate serine residues in the cytoplasmic portion of cytokine receptors to promote hemopoietic cell survival. We have isolated a kinase activity that is able to directly phosphorylate Ser585 in the cytoplasmic domain of the interleukin 3 (IL-3 and granulocyte macrophage colony stimulating factor (GM-CSF receptors and shown it to be PI3K. Physiological concentrations of cytokine in the picomolar range were sufficient for activating the protein kinase activity of PI3K leading to Ser585 phosphorylation and hemopoietic cell survival but did not activate PI3K lipid kinase signaling or promote proliferation. Blockade of PI3K lipid signaling by expression of the pleckstrin homology of Akt1 had no significant impact on the ability of picomolar concentrations of cytokine to promote hemopoietic cell survival. Furthermore, inducible expression of a mutant form of PI3K that is defective in lipid kinase activity but retains protein kinase activity was able to promote Ser585 phosphorylation and hemopoietic cell survival in the absence of cytokine. Blockade of p110α by RNA interference or multiple independent PI3K inhibitors not only blocked Ser585 phosphorylation in cytokine-dependent cells and primary human AML blasts, but also resulted in a block in survival signaling and cell death. Our findings demonstrate a new role for the protein kinase activity of PI3K in phosphorylating the cytoplasmic tail of the GM-CSF and IL-3 receptors to selectively regulate cell survival highlighting the importance of targeting

Specific leaf area estimation from leaf and canopy reflectance through optimization and validation of vegetation indices

NARCIS (Netherlands)

Ali, A.M.; Darvishzadeh, R.; Skidmore, A.K.; van Duren, I.C.

2017-01-01

Specific leaf area (SLA), which is defined as the leaf area per unit of dry leaf mass is an important component when assessing functional diversity and plays a key role in ecosystem modeling, linking plant carbon and water cycles as well as quantifying plant physiological processes. However, studies

Leaf hydraulic conductance declines in coordination with photosynthesis, transpiration and leaf water status as soybean leaves age regardless of soil moisture

Science.gov (United States)

Locke, Anna M.; Ort, Donald R.

2014-01-01

Photosynthesis requires sufficient water transport through leaves for stomata to remain open as water transpires from the leaf, allowing CO2 to diffuse into the leaf. The leaf water needs of soybean change over time because of large microenvironment changes over their lifespan, as leaves mature in full sun at the top of the canopy and then become progressively shaded by younger leaves developing above. Leaf hydraulic conductance (K leaf), a measure of the leaf’s water transport capacity, can often be linked to changes in microenvironment and transpiration demand. In this study, we tested the hypothesis that K leaf would decline in coordination with transpiration demand as soybean leaves matured and aged. Photosynthesis (A), stomatal conductance (g s) and leaf water potential (Ψleaf) were also measured at various leaf ages with both field- and chamber-grown soybeans to assess transpiration demand. K leaf was found to decrease as soybean leaves aged from maturity to shading to senescence, and this decrease was strongly correlated with midday A. Decreases in K leaf were further correlated with decreases in g s, although the relationship was not as strong as that with A. Separate experiments investigating the response of K leaf to drought demonstrated no acclimation of K leaf to drought conditions to protect against cavitation or loss of g s during drought and confirmed the effect of leaf age in K leaf observed in the field. These results suggest that the decline of leaf hydraulic conductance as leaves age keeps hydraulic supply in balance with demand without K leaf becoming limiting to transpiration water flux. PMID:25281701

Seagrass leaf element content

NARCIS (Netherlands)

Vonk, J.A.; Smulders, Fee O.H.; Christianen, Marjolijn J.A.; Govers, Laura L.

2017-01-01

Knowledge on the role of seagrass leaf elements and in particular micronutrients and their ranges is limited. We present a global database, consisting of 1126 unique leaf values for ten elements, obtained from literature and unpublished data, spanning 25 different seagrass species from 28 countries.

Estimating leaf area and leaf biomass of open-grown deciduous urban trees

Science.gov (United States)

David J. Nowak

1996-01-01

Logarithmic regression equations were developed to predict leaf area and leaf biomass for open-grown deciduous urban trees based on stem diameter and crown parameters. Equations based on crown parameters produced more reliable estimates. The equations can be used to help quantify forest structure and functions, particularly in urbanizing and urban/suburban areas.

Prophylactic effect of paw-paw leaf and bitter leaf extracts on the ...

African Journals Online (AJOL)

STORAGESEVER

2008-08-18

Aug 18, 2008 ... (ANOVA) and significant means separated using FLSD = LSD procedure as outlined in Obi (2002). RESULTS AND DISCUSSION. In pre-soaking, paw-paw leaf (PL) extract had no significant effect (P > 0.05) on the disease incidence at. 50% anthesis. Bitter leaf (BL) extract had a high signifi- cant effect (P ...

Structural coupling of SH2-kinase domains links Fes and Abl substrate recognition and kinase activation.

Science.gov (United States)

Filippakopoulos, Panagis; Kofler, Michael; Hantschel, Oliver; Gish, Gerald D; Grebien, Florian; Salah, Eidarus; Neudecker, Philipp; Kay, Lewis E; Turk, Benjamin E; Superti-Furga, Giulio; Pawson, Tony; Knapp, Stefan

2008-09-05

The SH2 domain of cytoplasmic tyrosine kinases can enhance catalytic activity and substrate recognition, but the molecular mechanisms by which this is achieved are poorly understood. We have solved the structure of the prototypic SH2-kinase unit of the human Fes tyrosine kinase, which appears specialized for positive signaling. In its active conformation, the SH2 domain tightly interacts with the kinase N-terminal lobe and positions the kinase alphaC helix in an active configuration through essential packing and electrostatic interactions. This interaction is stabilized by ligand binding to the SH2 domain. Our data indicate that Fes kinase activation is closely coupled to substrate recognition through cooperative SH2-kinase-substrate interactions. Similarly, we find that the SH2 domain of the active Abl kinase stimulates catalytic activity and substrate phosphorylation through a distinct SH2-kinase interface. Thus, the SH2 and catalytic domains of active Fes and Abl pro-oncogenic kinases form integrated structures essential for effective tyrosine kinase signaling.

The Link between Protein Kinase CK2 and Atypical Kinase Rio1

Directory of Open Access Journals (Sweden)

Konrad Kubiński

2017-02-01

Full Text Available The atypical kinase Rio1 is widespread in many organisms, ranging from Archaebacteria to humans, and is an essential factor in ribosome biogenesis. Little is known about the protein substrates of the enzyme and small-molecule inhibitors of the kinase. Protein kinase CK2 was the first interaction partner of Rio1, identified in yeast cells. The enzyme from various sources undergoes CK2-mediated phosphorylation at several sites and this modification regulates the activity of Rio1. The aim of this review is to present studies of the relationship between the two different kinases, with respect to CK2-mediated phosphorylation of Rio1, regulation of Rio1 activity, and similar susceptibility of the kinases to benzimidazole inhibitors.

Determination of the quantity of acetyl CoA carboxylase by [14C]methyl avidin binding

International Nuclear Information System (INIS)

Roman-Lopez, C.R.; Goodson, J.; Allred, J.B.

1987-01-01

Conditions are described under which monomeric [ 14 C]methyl avidin binds to SDS-denatured biotin enzymes and remains bound through polyacrylamide gel electrophoresis. The location of radioactive proteins on the dried gel was determined by fluorography and their identity was established by subunit molecular weight. The relative quantity of bound radioactive avidin, stoichiometrically equivalent to the molar quantity of biotin protein, can be determined by scanning the fluorograph with a soft laser densitometer. To determine the absolute quantity of biotin protein, the radioactive areas of the dried gel were cut out, resolubilized, and assayed for radioactivity. Since the specific radioactivity of the [ 14 C]methyl avidin was known, the quantity of avidin bound and therefore the quantity of biotin enzyme could be calculated. The method is illustrated by the analysis of purified acetyl CoA carboxylase and is applied to the analysis of biotin enzymes in isolated rat liver mitochondria

Joint Leaf chlorophyll and leaf area index retrieval from Landsat data using a regularized model inversion system

Science.gov (United States)

Leaf area index (LAI) and leaf chlorophyll (Chl) content represent key biophysical and biochemical controls on water, energy and carbon exchange processes in the terrestrial biosphere. In combination, LAI and leaf Chl content provide critical information on vegetation density, vitality and photosynt...

Regulation of Autophagy by Kinases

International Nuclear Information System (INIS)

Sridharan, Savitha; Jain, Kirti; Basu, Alakananda

2011-01-01

Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated protein kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK) and protein kinase C that are often deregulated in cancer and are important therapeutic targets

Regulation of Autophagy by Kinases

Energy Technology Data Exchange (ETDEWEB)

Sridharan, Savitha; Jain, Kirti; Basu, Alakananda, E-mail: alakananda.basu@unthsc.edu [Department of Molecular Biology and Immunology, Institute for Cancer Research, University of North Texas Health Science Center, Fort Worth, TX 76107 (United States)

2011-06-09

Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated protein kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK) and protein kinase C that are often deregulated in cancer and are important therapeutic targets.

Regulation of Autophagy by Kinases

Science.gov (United States)

Sridharan, Savitha; Jain, Kirti; Basu, Alakananda

2011-01-01

Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated protein kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK) and protein kinase C that are often deregulated in cancer and are important therapeutic targets. PMID:24212825

Regulation of Autophagy by Kinases

Directory of Open Access Journals (Sweden)

Savitha Sridharan

2011-06-01

Full Text Available Autophagy is a process of self-degradation that maintains cellular viability during periods of metabolic stress. Although autophagy is considered a survival mechanism when faced with cellular stress, extensive autophagy can also lead to cell death. Aberrations in autophagy are associated with several diseases, including cancer. Therapeutic exploitation of this process requires a clear understanding of its regulation. Although the core molecular components involved in the execution of autophagy are well studied there is limited information on how cellular signaling pathways, particularly kinases, regulate this complex process. Protein kinases are integral to the autophagy process. Atg1, the first autophagy-related protein identified, is a serine/threonine kinase and it is regulated by another serine/threonine kinase mTOR. Emerging studies suggest the participation of many different kinases in regulating various components/steps of this catabolic process. This review focuses on the regulation of autophagy by several kinases with particular emphasis on serine/threonine protein kinases such as mTOR, AMP-activated kinase, Akt, mitogen-activated protein kinase (ERK, p38 and JNK and protein kinase C that are often deregulated in cancer and are important therapeutic targets.

Using Leaf Samples to Establish a Library of Tropical Leaf Fingerprints

Science.gov (United States)

Ngo, P.; Nguyen, R.; Anderson, C.; Weiss, P.

2010-12-01

Variation in leaf chemistry is directly expressed in spectroscopic patterns of tropical canopies. The goal of the Spectranomics project is to explore this variation in the hopes of developing a method to measure tropical forest diversity remotely from airborne or space-bound spectroscopy in the future. We analyzed tomato leaves for various chemical compositions to better understand the Spectranomics approach to quantifying chemical data of tropical species. We also compared our data to standard data in each analysis. Our results allow us to give the tomato leaves a chemical signature in which we are able to use to compare to other leaf samples. Using this process, we are able to create a library of leaf signatures and document the variety of tree species in tropical forests around the world.

Leaf density explains variation in leaf mass per area in rice between cultivars and nitrogen treatments.

Science.gov (United States)

Xiong, Dongliang; Wang, Dan; Liu, Xi; Peng, Shaobing; Huang, Jianliang; Li, Yong

2016-05-01

Leaf mass per area (LMA) is an important leaf trait; however, correlations between LMA and leaf anatomical features and photosynthesis have not been fully investigated, especially in cereal crops. The objectives of this study were (a) to investigate the correlations between LMA and leaf anatomical traits; and (b) to clarify the response of LMA to nitrogen supply and its effect on photosynthetic nitrogen use efficiency (PNUE). In the present study, 11 rice varieties were pot grown under sufficient nitrogen (SN) conditions, and four selected rice cultivars were grown under low nitrogen (LN) conditions. Leaf anatomical traits, gas exchange and leaf N content were measured. There was large variation in LMA across selected rice varieties. Regression analysis showed that the variation in LMA was more closely related to leaf density (LD) than to leaf thickness (LT). LMA was positively related to the percentage of mesophyll tissue area (%mesophyll), negatively related to the percentage of epidermis tissue area (%epidermis) and unrelated to the percentage of vascular tissue area (%vascular). The response of LMA to N supplementation was dependent on the variety and was also mainly determined by the response of LD to N. Compared with SN, photosynthesis was significantly decreased under LN, while PNUE was increased. The increase in PNUE was more critical in rice cultivars with a higher LMA under SN supply. Leaf density is the major cause of the variation in LMA across rice varieties and N treatments, and an increase in LMA under high N conditions would aggravate the decrease in PNUE. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Arabidopsis thaliana ggt1 photorespiratory mutants maintain leaf carbon/nitrogen balance by reducing RuBisCO content and plant growth.

Science.gov (United States)

Dellero, Younès; Lamothe-Sibold, Marlène; Jossier, Mathieu; Hodges, Michael

2015-09-01

Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL L(-1) ). When compared to wild-type (WT) plants, air-grown ggt1 plants exhibited glyoxylate accumulation, global changes in amino acid amounts including a decrease in serine content, lower organic acid levels, and modified ATP/ADP and NADP(+) /NADPH ratios. When compared to WT plants, their net CO2 assimilation rates (An ) were 50% lower and this mirrored decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. High CO2 -grown ggt1 plants transferred to air revealed a rapid decrease of An and photosynthetic electron transfer rate while maintaining a high energetic state. Short-term (a night period and 4 h of light) transferred ggt1 leaves accumulated glyoxylate and exhibited low serine contents, while other amino acid levels were not modified. RuBisCO content, activity and activation state were not altered after a short-term transfer while the ATP/ADP ratio was lowered in ggt1 rosettes. However, plant growth and RuBisCO levels were both reduced in ggt1 leaves after a long-term (12 days) acclimation to air from high CO2 when compared to WT plants. The data are discussed with respect to a reduced photorespiratory carbon recycling in the mutants. It is proposed that the low An limits nitrogen-assimilation, this decreases leaf RuBisCO content until plants attain a new homeostatic state that maintains a constant C/N balance and leads to smaller, slower growing plants. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

7 CFR 30.2 - Leaf tobacco.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.2 Leaf...

7 CFR 29.3035 - Leaf structure.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements...

7 CFR 29.3526 - Leaf scrap.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling...

7 CFR 29.3034 - Leaf scrap.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

7 CFR 29.6022 - Leaf scrap.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results...

Infrared remote sensing for canopy temperature in paddy field and relationship between leaf temperature and leaf color

International Nuclear Information System (INIS)

Wakiyama, Y.

2002-01-01

Infrared remote sensing is used for crop monitoring, for example evaluation of water stress, detection of infected crops and estimation of transpiration and photosynthetic rates. This study was conducted to show another application of remote sensing information. The relationship between rice leaf temperature and chlorophyll content in the leaf blade was investigated by using thermography during the ripening period. The canopy of a rice community fertilized by top dressing was cooler than that not fertilized in a 1999 field experiment. In an experiment using thermocouples to measure leaf temperature, a rice leaf with high chlorophyll content was also cooler than that with a low chlorophyll content. Transpiration resistance and transpiration rate were measured with a porometer. Transpiration rate was higher with increasing chlorophyll content in the leaf blade. Stomatal aperture is related to chlorophyll content in the leaf blade. High degree of stomatal aperture is caused by high chlorophyll content in the leaf blade. As degree of stomatal aperture increases, transpiration rate increases. Therefore the rice leaf got cooler with increasing chlorophyll content in leaf blade. Paddy rice communities with different chlorophyll contents were provided with fertilization of different nitrogen levels on basal and top dressing in a 2000 field experiment. Canopy temperature of the rice community with high chlorophyll content was 0.85°C cooler than that of the rice community with low chlorophyll content. Results of this study revealed that infrared remote sensing could detect difference in chlorophyll contents in rice communities and could be used in fertilizer management in paddy fields. (author)

An analytical approach for optimizing the leaf design of a multi-leaf collimator in a linear accelerator

International Nuclear Information System (INIS)

Topolnjak, R; Heide, U A van der

2008-01-01

In this study, we present an analytical approach for optimizing the leaf design of a multi-leaf collimator (MLC) in a linear accelerator. Because leaf designs vary between vendors, our goal is to characterize and quantify the effects of different compromises which have to be made between performance parameters. Subsequently, an optimal leaf design for an earlier proposed six-bank MLC which combines a high-resolution field-shaping ability with a large field size is determined. To this end a model of the linac is created that includes the following parameters: the source size, the maximum field size, the distance between source and isocenter, and the leaf's design parameters. First, the optimal radius of the leaf tip was found. This optimum was defined by the requirement that the fluence intensity should fall from 80% of the maximum value to 20% in a minimal distance, defining the width of the fluence penumbra. A second requirement was that this penumbra width should be constant when a leaf moves from one side of the field to the other. The geometric, transmission and total penumbra width (80-20%) were calculated depending on the design parameters. The analytical model is in agreement with Elekta, Varian and Siemens collimator designs. For leaves thinner than 4 cm, the transmission penumbra becomes dominant, and for leaves close to the source the geometric penumbra plays a role. Finally, by choosing the leaf thickness of 3.5 cm, 4 cm and 5 cm from the lowest to the highest bank, respectively, an optimal leaf design for a six-bank MLC is achieved

Apparent Overinvestment in Leaf Venation Relaxes Leaf Morphological Constraints on Photosynthesis in Arid Habitats1[OPEN

Science.gov (United States)

de Boer, Hugo J.; Drake, Paul L.; Wendt, Erin; Price, Charles A.; Schulze, Ernst-Detlef; Turner, Neil C.; Nicolle, Dean

2016-01-01

Leaf veins supply the mesophyll with water that evaporates when stomata are open to allow CO2 uptake for photosynthesis. Theoretical analyses suggest that water is optimally distributed in the mesophyll when the lateral distance between veins (dx) is equal to the distance from these veins to the epidermis (dy), expressed as dx:dy ≈ 1. Although this theory is supported by observations of many derived angiosperms, we hypothesize that plants in arid environments may reduce dx:dy below unity owing to climate-specific functional adaptations of increased leaf thickness and increased vein density. To test our hypothesis, we assembled leaf hydraulic, morphological, and photosynthetic traits of 68 species from the Eucalyptus and Corymbia genera (termed eucalypts) along an aridity gradient in southwestern Australia. We inferred the potential gas-exchange advantage of reducing dx beyond dy using a model that links leaf morphology and hydraulics to photosynthesis. Our observations reveal that eucalypts in arid environments have thick amphistomatous leaves with high vein densities, resulting in dx:dy ratios that range from 1.6 to 0.15 along the aridity gradient. Our model suggests that, as leaves become thicker, the effect of reducing dx beyond dy is to offset the reduction in leaf gas exchange that would result from maintaining dx:dy at unity. This apparent overinvestment in leaf venation may be explained from the selective pressure of aridity, under which traits associated with long leaf life span, high hydraulic and thermal capacitances, and high potential rates of leaf water transport confer a competitive advantage. PMID:27784769

Transgene Expression and Repression in Transgenic Rats Bearing the Phosphoenolpyruvate Carboxykinase-Simian Virus 40 T Antigen or the Phosphoenolpyruvate Carboxykinase-Transforming Growth Factor-α Constructs

Science.gov (United States)

Haas, Michael J.; Dragan, Yvonne P.; Hikita, Hiroshi; Shimel, Randee; Takimoto, Koichi; Heath, Susan; Vaughan, Jennifer; Pitot, Henry C.

1999-01-01

Transgenic Sprague-Dawley rats expressing either human transforming growth factor-α (TGFα) or simian virus 40 large and small T antigen (TAg), each under the control of the phosphoenolpyruvate carboxykinase (PEPCK) promoter, were developed as an approach to the study of the promotion of hepatocarcinogenesis in the presence of a transgene regulatable by diet and/or hormones. Five lines of PEPCK-TGFα transgenic rats were established, each genetic line containing from one to several copies of the transgene per haploid genome. Two PEPCK-TAg transgenic founder rats were obtained, each with multiple copies of the transgene. Expression of the transgene was undetectable in the TGFα transgenic rats and could not be induced when the animals were placed on a high-protein, low-carbohydrate diet. The transgene was found to be highly methylated in all of these lines. No pathological alterations in the liver and intestine were observed at any time (up to 2 years) during the lives of these rats. One line of transgenic rats expressing the PEPCK-TAg transgene developed pancreatic islet cell hyperplasias and carcinomas, with few normal islets evident in the pancreas. This transgene is integrated as a hypomethylated tandem array of 10 to 12 copies on chromosome 8q11. Expression of large T antigen is highest in pancreatic neoplasms, but is also detectable in the normal brain, kidney, and liver. Mortality is most rapid in males, starting at 5 months of age and reaching 100% by 8 months. Morphologically, islet cell differentiation in the tumors ranges from poor to well differentiated, with regions of necrosis and fibrosis. Spontaneous metastasis of TAg-positive tumor cells to regional lymph nodes was observed. These studies indicate the importance of DNA methylation in the repression of specific transgenes in the rat. However, the expression of the PEPCK-TAg induces neoplastic transformation in islet cells, probably late in neuroendocrine cell differentiation. T antigen expression

7 CFR 29.6023 - Leaf structure.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its...

7 CFR 29.1030 - Leaf structure.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

7 CFR 29.3527 - Leaf structure.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

Comparison of dwarf bamboos (Indocalamus sp.) leaf parameters to determine relationship between spatial density of plants and total leaf area per plant.

Science.gov (United States)

Shi, Pei-Jian; Xu, Qiang; Sandhu, Hardev S; Gielis, Johan; Ding, Yu-Long; Li, Hua-Rong; Dong, Xiao-Bo

2015-10-01

The relationship between spatial density and size of plants is an important topic in plant ecology. The self-thinning rule suggests a -3/2 power between average biomass and density or a -1/2 power between stand yield and density. However, the self-thinning rule based on total leaf area per plant and density of plants has been neglected presumably because of the lack of a method that can accurately estimate the total leaf area per plant. We aimed to find the relationship between spatial density of plants and total leaf area per plant. We also attempted to provide a novel model for accurately describing the leaf shape of bamboos. We proposed a simplified Gielis equation with only two parameters to describe the leaf shape of bamboos one model parameter represented the overall ratio of leaf width to leaf length. Using this method, we compared some leaf parameters (leaf shape, number of leaves per plant, ratio of total leaf weight to aboveground weight per plant, and total leaf area per plant) of four bamboo species of genus Indocalamus Nakai (I. pedalis (Keng) P.C. Keng, I. pumilus Q.H. Dai and C.F. Keng, I. barbatus McClure, and I. victorialis P.C. Keng). We also explored the possible correlation between spatial density and total leaf area per plant using log-linear regression. We found that the simplified Gielis equation fit the leaf shape of four bamboo species very well. Although all these four species belonged to the same genus, there were still significant differences in leaf shape. Significant differences also existed in leaf area per plant, ratio of leaf weight to aboveground weight per plant, and leaf length. In addition, we found that the total leaf area per plant decreased with increased spatial density. Therefore, we directly demonstrated the self-thinning rule to improve light interception.

The SH2 domain of Abl kinases regulates kinase autophosphorylation by controlling activation loop accessibility

Science.gov (United States)

Lamontanara, Allan Joaquim; Georgeon, Sandrine; Tria, Giancarlo; Svergun, Dmitri I.; Hantschel, Oliver

2014-11-01

The activity of protein kinases is regulated by multiple molecular mechanisms, and their disruption is a common driver of oncogenesis. A central and almost universal control element of protein kinase activity is the activation loop that utilizes both conformation and phosphorylation status to determine substrate access. In this study, we use recombinant Abl tyrosine kinases and conformation-specific kinase inhibitors to quantitatively analyse structural changes that occur after Abl activation. Allosteric SH2-kinase domain interactions were previously shown to be essential for the leukemogenesis caused by the Bcr-Abl oncoprotein. We find that these allosteric interactions switch the Abl activation loop from a closed to a fully open conformation. This enables the trans-autophosphorylation of the activation loop and requires prior phosphorylation of the SH2-kinase linker. Disruption of the SH2-kinase interaction abolishes activation loop phosphorylation. Our analysis provides a molecular mechanism for the SH2 domain-dependent activation of Abl that may also regulate other tyrosine kinases.

Transcriptional analyses of natural leaf senescence in maize.

Directory of Open Access Journals (Sweden)

Wei Yang Zhang

Full Text Available Leaf senescence is an important biological process that contributes to grain yield in crops. To study the molecular mechanisms underlying natural leaf senescence, we harvested three different developmental ear leaves of maize, mature leaves (ML, early senescent leaves (ESL, and later senescent leaves (LSL, and analyzed transcriptional changes using RNA-sequencing. Three sets of data, ESL vs. ML, LSL vs. ML, and LSL vs. ESL, were compared, respectively. In total, 4,552 genes were identified as differentially expressed. Functional classification placed these genes into 18 categories including protein metabolism, transporters, and signal transduction. At the early stage of leaf senescence, genes involved in aromatic amino acids (AAAs biosynthetic process and transport, cellular polysaccharide biosynthetic process, and the cell wall macromolecule catabolic process, were up-regulated. Whereas, genes involved in amino acid metabolism, transport, apoptosis, and response to stimulus were up-regulated at the late stage of leaf senescence. Further analyses reveals that the transport-related genes at the early stage of leaf senescence potentially take part in enzyme and amino acid transport and the genes upregulated at the late stage are involved in sugar transport, indicating nutrient recycling mainly takes place at the late stage of leaf senescence. Comparison between the data of natural leaf senescence in this study and previously reported data for Arabidopsis implies that the mechanisms of leaf senescence in maize are basically similar to those in Arabidopsis. A comparison of natural and induced leaf senescence in maize was performed. Athough many basic biological processes involved in senescence occur in both types of leaf senescence, 78.07% of differentially expressed genes in natural leaf senescence were not identifiable in induced leaf senescence, suggesting that differences in gene regulatory network may exist between these two leaf senescence

Differential transcription and message stability of two genes encoding soybean ribulose 1,5-bisphosphate carboxylase small subunit

International Nuclear Information System (INIS)

Shirley, B.W.; Berry-Lowe, S.L.; Grandbastien, M.A.; Zurfluh, L.L.; Shah, D.M.; Meagher, R.B.

1987-01-01

The expression of two closely related soybean ribulose bisphosphate carboxylase small subunit (Rubisco ss) genes, SRS1 and SRS4, has been compared. These genes account for approximately 2-4% of the total transcription in light grown leaves, SRS4 being twice as transcriptionally active as SRS1. The transcription of these genes is reduced more than 30 fold after a pulse of far-red light or extended periods of darkness. When etiolated seedlings are shifted to the light the transcription of both genes increases 30-50 fold. Despite this 30-fold range in transcriptional expression the steady state mRNA levels in light and dark grown tissue differ by less than 8 fold. This suggests that the mRNAs are less stable in light grown tissue. 38 refs., 5 figs

Role of adiponectin/phosphatidylinositol 3-kinase/protein kinase B ...

African Journals Online (AJOL)

The adiponectin/phosphatidylinositol 3-kinase/protein kinase B (ADP/PI3k/Akt) signal transduction pathway has an important role in promoting cell survival. This study was designed to determine if the ADP/PI3K/Akt signaling pathway has a role in the mechanism of ischemia–reperfusion injury in vivo. Sprague–Dawley rats ...

Effects of nitrogen infiltration into plant tissue on the metabolism of carbon, with special reference to Themeda triandra Forssk

Energy Technology Data Exchange (ETDEWEB)

Amory, A M

1983-01-01

The infiltration of nitrate and ammonia into Themeda triandra and Zea mays leaf tissue influenced the carbon dioxide gas exchange characteristics: 1) the carbon dioxide compensation point increased, 2) the net photosynthetic rate was increased by the nitrate ion and decreased by the ammonium ion, and 3) dark respiration was unaffected. /sup 14/CO/sub 2/ assimilation and the partitioning of /sup 14/C by Themeda triandra leaves were influenced by the infiltration of both forms of nitrogen; the amino acid fraction changed in both composition and concentration. Nitrogen infiltration increased the activities of the following enzymes: aspartate amino-transferase, PEP carboxylase and RuBP carboxylase. Methionine sulphoximine (inhibitor of glutamate synthetase) increased the carbon dioxide compensation point and formate pool size. Infiltration of nitrate and ammonia enhanced the /sup 14/C uptake from labelled glycolate, glyoxylate and formate into the water soluble fraction of Themeda triandra leaves. The activities of RuBP carboxylase and RuBP oxygenase (to a greater extent) were increased by the addition of nitrate and ammonia in vitro.

Tyrosine kinases in rheumatoid arthritis

Directory of Open Access Journals (Sweden)

Kobayashi Akiko

2011-08-01

Full Text Available Abstract Rheumatoid arthritis (RA is an inflammatory, polyarticular joint disease. A number of cellular responses are involved in the pathogenesis of rheumatoid arthritis, including activation of inflammatory cells and cytokine expression. The cellular responses involved in each of these processes depends on the specific signaling pathways that are activated; many of which include protein tyrosine kinases. These pathways include the mitogen-activated protein kinase pathway, Janus kinases/signal transducers and activators transcription pathway, spleen tyrosine kinase signaling, and the nuclear factor κ-light-chain-enhancer of activated B cells pathway. Many drugs are in development to target tyrosine kinases for the treatment of RA. Based on the number of recently published studies, this manuscript reviews the role of tyrosine kinases in the pathogenesis of RA and the potential role of kinase inhibitors as new therapeutic strategies of RA.

Novel small-molecule AMPK activator orally exerts beneficial effects on diabetic db/db mice

Energy Technology Data Exchange (ETDEWEB)

Li, Yuan-Yuan; Yu, Li-Fang; Zhang, Li-Na; Qiu, Bei-Ying; Su, Ming-Bo; Wu, Fang; Chen, Da-Kai; Pang, Tao; Gu, Min; Zhang, Wei; Ma, Wei-Ping; Jiang, Hao-Wen; Li, Jing-Ya, E-mail: jyli@mail.shcnc.ac.cn; Nan, Fa-Jun, E-mail: fjnan@mail.shcnc.ac.cn; Li, Jia, E-mail: jli@mail.shcnc.ac.cn

2013-12-01

AMP-activated protein kinase (AMPK), which is a pivotal guardian of whole-body energy metabolism, has become an attractive therapeutic target for metabolic syndrome. Previously, using a homogeneous scintillation proximity assay, we identified the small-molecule AMPK activator C24 from an optimization based on the original allosteric activator PT1. In this paper, the AMPK activation mechanism of C24 and its potential beneficial effects on glucose and lipid metabolism on db/db mice were investigated. C24 allosterically stimulated inactive AMPK α subunit truncations and activated AMPK heterotrimers by antagonizing autoinhibition. In primary hepatocytes, C24 increased the phosphorylation of AMPK downstream target acetyl-CoA carboxylase dose-dependently without changing intracellular AMP/ATP ratio, indicating its allosteric activation in cells. Through activating AMPK, C24 decreased glucose output by down-regulating mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) in primary hepatocytes. C24 also decreased the triglyceride and cholesterol contents in HepG2 cells. Due to its improved bioavailability, chronic oral treatment with multiple doses of C24 significantly reduced blood glucose and lipid levels in plasma, and improved the glucose tolerance of diabetic db/db mice. The hepatic transcriptional levels of PEPCK and G6Pase were reduced. These results demonstrate that this orally effective activator of AMPK represents a novel approach to the treatment of metabolic syndrome. - Highlights: • C24 activates AMPK through antagonizing autoinhibition within α subunit. • C24 activates AMPK in hepatocytes and decreases glucose output via AMPK. • C24 exerts beneficial effects on diabetic db/db mice. • C24 represents a novel therapeutic for treatment of metabolic syndrome.

Key enzymes of gluconeogenesis are dose-dependently reduced in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-treated rats

Energy Technology Data Exchange (ETDEWEB)

Weber, L.W.D.; Rozman, K. (Kansas Univ., Kansas City, KS (USA). Dept. of Pharmacology, Toxicology and Therapeutics Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen (GSF), Neuherberg (Germany, F.R.). Inst. fuer Toxikologie); Lebofsky, M. (Kansas Univ., Kansas City, KS (USA). Dept. of Pharmacology, Toxicology and Therapeutics); Greim, H. (Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen (GSF), Neuherberg (Germany, F.R.). Inst. fuer Toxikologie)

1991-02-01

Male Sprague-Dawley rats (240-245 g) were dosed ip with 5, 15, 25, or 125 {mu}g/kg -,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in corn oil. Ad libitum-fed and pair-fed controls received vehicle (4 ml/kg) alone. Two or 8 days after dosing five rats of each group were sacrificed, their livers removed and assayed for the activities of three gluconeogenic enzymes, (phosphoenol-pyruvate carboxykinase (PEPCK; EC 4.1.1.32), pyruvate carboxylase (PC; EC 6.4.1.1.), and glucose-6-phosphatase (G-6-Pase, EC 3.1.3.9)), and one glycolytic enzyme (pyruvate kinase (PK; EC 2.7.1.40)) by established procedures. The activity of PK was not affected by TCDD at either time point. The activity of G-6-Phase tended to be decreased in TCDD-treated animals, as compared to pair-fed controls, but the decrease was variable without an apparent dose-response. The activity of PEPCK was significantly decreased 2 days after dosing, but a clear dose-response was apparent only at the 8-day time point. Maximum loss of activity at the highest dose was 56% below pair-fed control levels. PC activity was slightly decreased 2 days after TCDD treatment and displayed statistically significant, dose-dependent reduction by 8 days after dosing with a 49% loss of enzyme activity after the highest dose. It is concluded that inhibition of gluconeogenesis by TCDD previously demonstrated in vivo is probably due to decreased activities of PEPCK and PC. The data also support the prevailing view that PEPCK and PC are rate-determining enzymes in gluconeogenesis. (orig.).

Novel small-molecule AMPK activator orally exerts beneficial effects on diabetic db/db mice

International Nuclear Information System (INIS)

Li, Yuan-Yuan; Yu, Li-Fang; Zhang, Li-Na; Qiu, Bei-Ying; Su, Ming-Bo; Wu, Fang; Chen, Da-Kai; Pang, Tao; Gu, Min; Zhang, Wei; Ma, Wei-Ping; Jiang, Hao-Wen; Li, Jing-Ya; Nan, Fa-Jun; Li, Jia

2013-01-01

AMP-activated protein kinase (AMPK), which is a pivotal guardian of whole-body energy metabolism, has become an attractive therapeutic target for metabolic syndrome. Previously, using a homogeneous scintillation proximity assay, we identified the small-molecule AMPK activator C24 from an optimization based on the original allosteric activator PT1. In this paper, the AMPK activation mechanism of C24 and its potential beneficial effects on glucose and lipid metabolism on db/db mice were investigated. C24 allosterically stimulated inactive AMPK α subunit truncations and activated AMPK heterotrimers by antagonizing autoinhibition. In primary hepatocytes, C24 increased the phosphorylation of AMPK downstream target acetyl-CoA carboxylase dose-dependently without changing intracellular AMP/ATP ratio, indicating its allosteric activation in cells. Through activating AMPK, C24 decreased glucose output by down-regulating mRNA levels of phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) in primary hepatocytes. C24 also decreased the triglyceride and cholesterol contents in HepG2 cells. Due to its improved bioavailability, chronic oral treatment with multiple doses of C24 significantly reduced blood glucose and lipid levels in plasma, and improved the glucose tolerance of diabetic db/db mice. The hepatic transcriptional levels of PEPCK and G6Pase were reduced. These results demonstrate that this orally effective activator of AMPK represents a novel approach to the treatment of metabolic syndrome. - Highlights: • C24 activates AMPK through antagonizing autoinhibition within α subunit. • C24 activates AMPK in hepatocytes and decreases glucose output via AMPK. • C24 exerts beneficial effects on diabetic db/db mice. • C24 represents a novel therapeutic for treatment of metabolic syndrome

Functional characterization of a constitutively active kinase variant of Arabidopsis phototropin 1.

Science.gov (United States)

Petersen, Jan; Inoue, Shin-Ichiro; Kelly, Sharon M; Sullivan, Stuart; Kinoshita, Toshinori; Christie, John M

2017-08-18

Phototropins (phots) are plasma membrane-associated serine/threonine kinases that coordinate a range of processes linked to optimizing photosynthetic efficiency in plants. These photoreceptors contain two light-, oxygen-, or voltage-sensing (LOV) domains within their N terminus, with each binding one molecule of flavin mononucleotide as a UV/blue light-absorbing chromophore. Although phots contain two LOV domains, light-induced activation of the C-terminal kinase domain and subsequent receptor autophosphorylation is controlled primarily by the A'α-LOV2-Jα photosensory module. Mutations that disrupt interactions between the LOV2 core and its flanking helical segments can uncouple this mode of light regulation. However, the impact of these mutations on phot function in Arabidopsis has not been explored. Here we report that histidine substitution of Arg-472 located within the A'α-helix of Arabidopsis phot1 constitutively activates phot1 kinase activity in vitro without affecting LOV2 photochemistry. Expression analysis of phot1 R472H in the phot-deficient mutant confirmed that it is autophosphorylated in darkness in vivo but unable to initiate phot1 signaling in the absence of light. Instead, we found that phot1 R472H is poorly functional under low-light conditions but can restore phototropism, chloroplast accumulation, stomatal opening, and leaf positioning and expansion at higher light intensities. Our findings suggest that Arabidopsis can adapt to the elevated phosphorylation status of the phot1 R472H mutant in part by reducing its stability, whereas the activity of the mutant under high-light conditions can be attributed to additional increases in LOV2-mediated photoreceptor autophosphorylation. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Ozone induced leaf loss and decreased leaf production of European Holly (Ilex aquifolium L.) over multiple seasons

International Nuclear Information System (INIS)

Ranford, Jonathan; Reiling, Kevin

2007-01-01

European Holly (Ilex aquifolium L.) was used to study the impact of one short (28 day) ozone fumigation episode on leaf production, leaf loss and stomatal conductance (g s ), in order to explore potential longer term effects over 3 growing seasons. Young I. aquifolium plants received an episode of either charcoal-filtered air or charcoal-filtered air with 70 nl l -1 O 3 added for 7 h d -1 over a 28 day period from June 15th 1996, then placed into ambient environment, Stoke-on-Trent, U.K. Data were collected per leaf cohort over the next three growing seasons. Ozone exposure significantly increased leaf loss and stomatal conductance and reduced leaf production over all subsequent seasons. Impact of the initial ozone stress was still detected in leaves that had no direct experimental ozone exposure. This study has shown the potential of ozone to introduce long-term phenological perturbations into ecosystems by influencing productivity over a number of seasons. - Ozone significantly alters Ilex aquifolium leaf production and loss over multiple seasons

Thymidine kinases in archaea

DEFF Research Database (Denmark)

Clausen, A.R.; Matakos, A.; Sandrini, Michael

2006-01-01

Twenty-six fully sequenced archaeal genomes were searched for genes coding for putative deoxyribonucleoside kinases (dNKs). We identified only 5 human-like thymidine kinase 1 genes (TK1s) and none for non-TK1 kinases. Four TK1s were identified in the Euryarchaea and one was found in the Crenarcha...

Kinase impact assessment in the landscape of fusion genes that retain kinase domains: a pan-cancer study

Science.gov (United States)

Kim, Pora; Jia, Peilin; Zhao, Zhongming

2018-01-01

Abstract Assessing the impact of kinase in gene fusion is essential for both identifying driver fusion genes (FGs) and developing molecular targeted therapies. Kinase domain retention is a crucial factor in kinase fusion genes (KFGs), but such a systematic investigation has not been done yet. To this end, we analyzed kinase domain retention (KDR) status in chimeric protein sequences of 914 KFGs covering 312 kinases across 13 major cancer types. Based on 171 kinase domain-retained KFGs including 101 kinases, we studied their recurrence, kinase groups, fusion partners, exon-based expression depth, short DNA motifs around the break points and networks. Our results, such as more KDR than 5′-kinase fusion genes, combinatorial effects between 3′-KDR kinases and their 5′-partners and a signal transduction-specific DNA sequence motif in the break point intronic sequences, supported positive selection on 3′-kinase fusion genes in cancer. We introduced a degree-of-frequency (DoF) score to measure the possible number of KFGs of a kinase. Interestingly, kinases with high DoF scores tended to undergo strong gene expression alteration at the break points. Furthermore, our KDR gene fusion network analysis revealed six of the seven kinases with the highest DoF scores (ALK, BRAF, MET, NTRK1, NTRK3 and RET) were all observed in thyroid carcinoma. Finally, we summarized common features of ‘effective’ (highly recurrent) kinases in gene fusions such as expression alteration at break point, redundant usage in multiple cancer types and 3′-location tendency. Collectively, our findings are useful for prioritizing driver kinases and FGs and provided insights into KFGs’ clinical implications. PMID:28013235

Acetyl-CoA Carboxylase-α Inhibitor TOFA Induces Human Cancer Cell Apoptosis

Science.gov (United States)

Wang, Chun; Xu, Canxin; Sun, Mingwei; Luo, Dixian; Liao, Duan-fang; Cao, Deliang

2009-01-01

Acetyl-CoA carboxylase-α (ACCA) is a rate-limiting enzyme in long chain fatty acid synthesis, playing a critical role in cellular energy storage and lipid synthesis. ACCA is upregulated in multiple types of human cancers and small interfering RNA-mediated ACCA silencing in human breast and prostate cancer cells results in oxidative stress and apoptosis. This study reports for the first time that TOFA (5-tetradecyloxy-2-furoic acid), an allosteric inhibitor of ACCA, is cytotoxic to lung cancer cells NCI-H460 and colon carcinoma cells HCT-8 and HCT-15, with an IC50 at approximately 5.0, 5.0, and 4.5 μg/ml, respectively. TOFA at 1.0–20.0 μg/ml effectively blocked fatty acid synthesis and induced cell death in a dose-dependent manner. The cell death was characterized with PARP cleavage, DNA fragmentation, and annexin-V staining, all of which are the features of the apoptosis. Supplementing simultaneously the cells with palmitic acids (100 μM), the end-products of the fatty acid synthesis pathway, prevented the apoptosis induced by TOFA. Taken together, these data suggest that TOFA is a potent cytotoxic agent to lung and colon cancer cells, inducing apoptosis through disturbing their fatty acid synthesis. PMID:19450551

Acetyl-CoA carboxylase-alpha inhibitor TOFA induces human cancer cell apoptosis.

Science.gov (United States)

Wang, Chun; Xu, Canxin; Sun, Mingwei; Luo, Dixian; Liao, Duan-Fang; Cao, Deliang

2009-07-31

Acetyl-CoA carboxylase-alpha (ACCA) is a rate-limiting enzyme in long chain fatty acid synthesis, playing a critical role in cellular energy storage and lipid synthesis. ACCA is upregulated in multiple types of human cancers and small interfering RNA-mediated ACCA silencing in human breast and prostate cancer cells results in oxidative stress and apoptosis. This study reports for the first time that TOFA (5-tetradecyloxy-2-furoic acid), an allosteric inhibitor of ACCA, is cytotoxic to lung cancer cells NCI-H460 and colon carcinoma cells HCT-8 and HCT-15, with an IC(50) at approximately 5.0, 5.0, and 4.5 microg/ml, respectively. TOFA at 1.0-20.0 microg/ml effectively blocked fatty acid synthesis and induced cell death in a dose-dependent manner. The cell death was characterized with PARP cleavage, DNA fragmentation, and annexin-V staining, all of which are the features of the apoptosis. Supplementing simultaneously the cells with palmitic acids (100 microM), the end-products of the fatty acid synthesis pathway, prevented the apoptosis induced by TOFA. Taken together, these data suggest that TOFA is a potent cytotoxic agent to lung and colon cancer cells, inducing apoptosis through disturbing their fatty acid synthesis.

Photoperiod-H1 (Ppd-H1) Controls Leaf Size.

Science.gov (United States)

Digel, Benedikt; Tavakol, Elahe; Verderio, Gabriele; Tondelli, Alessandro; Xu, Xin; Cattivelli, Luigi; Rossini, Laura; von Korff, Maria

2016-09-01

Leaf size is a major determinant of plant photosynthetic activity and biomass; however, it is poorly understood how leaf size is genetically controlled in cereal crop plants like barley (Hordeum vulgare). We conducted a genome-wide association scan for flowering time, leaf width, and leaf length in a diverse panel of European winter cultivars grown in the field and genotyped with a single-nucleotide polymorphism array. The genome-wide association scan identified PHOTOPERIOD-H1 (Ppd-H1) as a candidate gene underlying the major quantitative trait loci for flowering time and leaf size in the barley population. Microscopic phenotyping of three independent introgression lines confirmed the effect of Ppd-H1 on leaf size. Differences in the duration of leaf growth and consequent variation in leaf cell number were responsible for the leaf size differences between the Ppd-H1 variants. The Ppd-H1-dependent induction of the BARLEY MADS BOX genes BM3 and BM8 in the leaf correlated with reductions in leaf size and leaf number. Our results indicate that leaf size is controlled by the Ppd-H1- and photoperiod-dependent progression of plant development. The coordination of leaf growth with flowering may be part of a reproductive strategy to optimize resource allocation to the developing inflorescences and seeds. © 2016 American Society of Plant Biologists. All rights reserved.

Regulation of glycolysis and level of the Crassulacean acid metabolism.

Science.gov (United States)

Pierre, J N; Queiroz, O

1979-01-01

Glycolysis shows different patterns of operation and different control steps, depending on whether the level of Crassulacean acid metabolism (CAM) is low or high in the leaves of Kalanchoe blossfeldiana v.Poelln., when subjected to appropriate photoperiodic treatments: at a low level of CAM operation all the enzymes of glycolysis and phosphoenol pyruvate (PEP) carboxylase present a 12 h rhythm of capacity, resulting from the superposition of two 24h rhythms out of phase; phosphofructokinase appears to be the main regulation step; attainment of high CAM level involves (1) an increase in the peak of capacity occurring during the night of all the glycolytic enzymes, thus achieving an over-all 24h rhythm, in strict allometric coherence with the increase in PEP carboxylase capacity, (2) the establishment of different phase relationships between the rhythms of enzyme capacity, and (3) the control of three enzymic steps (phosphofructokinase, the group 3-P-glyceraldehyde dehydrogenase - 3-P-glycerate kinase, and PEP carboxylase). Results show that the hypothesis of allosteric regulation of phosphofructokinase (by PEP) and PEP carboxylase (by malate and glucose-6-P) cannot provide a complete explanation for the temporal organization of glycolysis and that changes in the phase relationships between the rhythms of enzyme capacity along the pathway and a strict correlation between the level of PEP carboxylase capacity and the levels of capacity of the glycolytic enzymes are important components of the regulation of glycolysis in relation to CAM.

Phosphorylation of varicella-zoster virus glycoprotein gpI by mammalian casein kinase II and casein kinase I

International Nuclear Information System (INIS)

Grose, C.; Jackson, W.; Traugh, J.A.

1989-01-01

Varicella-zoster virus (VZV) glycoprotein gpI is the predominant viral glycoprotein within the plasma membranes of infected cells. This viral glycoprotein is phosphorylated on its polypeptide backbone during biosynthesis. In this report, the authors investigated the protein kinases which participate in the phosphorylation events. Under in vivo conditions, VZV gpI was phosphorylated on its serine and threonine residues by protein kinases present within lysates of either VZV-infected or uninfected cells. Because this activity was diminished by heparin, a known inhibitor of casein kinase II, isolated gpI was incubated with purified casein kinase II and shown to be phosphorylated in an in vitro assay containing [γ- 32 P]ATP. The same glycoprotein was phosphorylated when [ 32 P]GTP was substituted for [ 32 P]ATP in the protein kinase assay. They also tested whether VZV gpI was phosphorylated by two other ubiquitous mammalian protein kinases--casein kinase I and cyclic AMP-dependent kinase--and found that only casein kinase I modified gpI. When the predicted 623-amino-acid sequence of gpI was examined, two phosphorylation sites known to be optimal for casein kinase II were observed. In summary, this study showed that VZV gpI was phosphorylated by each of two mammalian protein kinases (casein kinase I and casein kinase II) and that potential serine-threonine phosphorylation sites for each of these two kinases were present in the viral glycoprotein

Abundance and distribution of archaeal acetyl-CoA/propionyl-CoA carboxylase genes indicative for putatively chemoautotrophic Archaea in the tropical Atlantic's interior

OpenAIRE

Bergauer, Kristin; Sintes, Eva; van Bleijswijk, Judith; Witte, Harry; Herndl, Gerhard J; Lueders, Tillmann

2013-01-01

Recently, evidence suggests that dark CO2 fixation in the pelagic realm of the ocean does not only occur in the suboxic and anoxic water bodies but also in the oxygenated meso- and bathypelagic waters of the North Atlantic. To elucidate the significance and phylogeny of the key organisms mediating dark CO2 fixation in the tropical Atlantic, we quantified functional genes indicative for CO2 fixation. We used a Q-PCR-based assay targeting the bifunctional acetyl-CoA/propionyl-CoA carboxylase (a...

BRCA1 affects lipid synthesis through its interaction with acetyl-CoA carboxylase.

Science.gov (United States)

Moreau, Karen; Dizin, Eva; Ray, Hind; Luquain, Céline; Lefai, Etienne; Foufelle, Fabienne; Billaud, Marc; Lenoir, Gilbert M; Venezia, Nicole Dalla

2006-02-10

Germ line alterations in BRCA1 (breast cancer susceptibility gene 1) are associated with an increased susceptibility to breast and ovarian cancer. BRCA1 acts as a scaffold protein implicated in multiple cellular functions, such as transcription, DNA repair, and ubiquitination. However, the molecular mechanisms responsible for tumorigenesis are not yet fully understood. We have recently demonstrated that BRCA1 interacts in vivo with acetyl coenzyme A carboxylase alpha (ACCA) through its tandem of BRCA1 C terminus (BRCT) domains. To understand the biological function of the BRCA1.ACCA complex, we sought to determine whether BRCA1 is a regulator of lipogenesis through its interaction with ACCA. We showed here that RNA inhibition-mediated down-regulation of BRCA1 expression induced a marked increase in the fatty acid synthesis. We then delineated the biochemical characteristics of the complex and found that BRCA1 interacts solely with the phosphorylated and inactive form of ACCA (P-ACCA). Finally, we demonstrated that BRCA1 affects lipid synthesis by preventing P-ACCA dephosphorylation. These results suggest that BRCA1 affects lipogenesis through binding to P-ACCA, providing a new mechanism by which BRCA1 may exert a tumor suppressor function.

Receptor-interacting protein (RIP) kinase family

OpenAIRE

Zhang, Duanwu; Lin, Juan; Han, Jiahuai

2010-01-01

Receptor-interacting protein (RIP) kinases are a group of threonine/serine protein kinases with a relatively conserved kinase domain but distinct non-kinase regions. A number of different domain structures, such as death and caspase activation and recruitment domain (CARD) domains, were found in different RIP family members, and these domains should be keys in determining the specific function of each RIP kinase. It is known that RIP kinases participate in different biological processes, incl...

Wind increases leaf water use efficiency.

Science.gov (United States)

Schymanski, Stanislaus J; Or, Dani

2016-07-01

A widespread perception is that, with increasing wind speed, transpiration from plant leaves increases. However, evidence suggests that increasing wind speed enhances carbon dioxide (CO2 ) uptake while reducing transpiration because of more efficient convective cooling (under high solar radiation loads). We provide theoretical and experimental evidence that leaf water use efficiency (WUE, carbon uptake per water transpired) commonly increases with increasing wind speed, thus improving plants' ability to conserve water during photosynthesis. Our leaf-scale analysis suggests that the observed global decrease in near-surface wind speeds could have reduced WUE at a magnitude similar to the increase in WUE attributed to global rise in atmospheric CO2 concentrations. However, there is indication that the effect of long-term trends in wind speed on leaf gas exchange may be compensated for by the concurrent reduction in mean leaf sizes. These unintuitive feedbacks between wind, leaf size and water use efficiency call for re-evaluation of the role of wind in plant water relations and potential re-interpretation of temporal and geographic trends in leaf sizes. © 2015 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.

Cinnamon Extract Enhances Glucose Uptake in 3T3-L1 Adipocytes and C2C12 Myocytes by Inducing LKB1-AMP-Activated Protein Kinase Signaling

Science.gov (United States)

Shen, Yan; Honma, Natsumi; Kobayashi, Katsuya; Jia, Liu Nan; Hosono, Takashi; Shindo, Kazutoshi; Ariga, Toyohiko; Seki, Taiichiro

2014-01-01

We previously demonstrated that cinnamon extract (CE) ameliorates type 1 diabetes induced by streptozotocin in rats through the up-regulation of glucose transporter 4 (GLUT4) translocation in both muscle and adipose tissues. This present study was aimed at clarifying the detailed mechanism(s) with which CE increases the glucose uptake in vivo and in cell culture systems using 3T3-L1 adipocytes and C2C12 myotubes in vitro. Specific inhibitors of key enzymes in insulin signaling and AMP-activated protein kinase (AMPK) signaling pathways, as well as small interference RNA, were used to examine the role of these kinases in the CE-induced glucose uptake. The results showed that CE stimulated the phosphorylation of AMPK and acetyl-CoA carboxylase. An AMPK inhibitor and LKB1 siRNA blocked the CE-induced glucose uptake. We also found for the first time that insulin suppressed AMPK activation in the adipocyte. To investigate the effect of CE on type 2 diabetes in vivo, we further performed oral glucose tolerance tests and insulin tolerance tests in type 2 diabetes model rats administered with CE. The CE improved glucose tolerance in oral glucose tolerance tests, but not insulin sensitivity in insulin tolerance test. In summary, these results indicate that CE ameliorates type 2 diabetes by inducing GLUT4 translocation via the AMPK signaling pathway. We also found insulin antagonistically regulates the activation of AMPK. PMID:24551069

Relating Stomatal Conductance to Leaf Functional Traits.

Science.gov (United States)

Kröber, Wenzel; Plath, Isa; Heklau, Heike; Bruelheide, Helge

2015-10-12

Leaf functional traits are important because they reflect physiological functions, such as transpiration and carbon assimilation. In particular, morphological leaf traits have the potential to summarize plants strategies in terms of water use efficiency, growth pattern and nutrient use. The leaf economics spectrum (LES) is a recognized framework in functional plant ecology and reflects a gradient of increasing specific leaf area (SLA), leaf nitrogen, phosphorus and cation content, and decreasing leaf dry matter content (LDMC) and carbon nitrogen ratio (CN). The LES describes different strategies ranging from that of short-lived leaves with high photosynthetic capacity per leaf mass to long-lived leaves with low mass-based carbon assimilation rates. However, traits that are not included in the LES might provide additional information on the species' physiology, such as those related to stomatal control. Protocols are presented for a wide range of leaf functional traits, including traits of the LES, but also traits that are independent of the LES. In particular, a new method is introduced that relates the plants' regulatory behavior in stomatal conductance to vapor pressure deficit. The resulting parameters of stomatal regulation can then be compared to the LES and other plant functional traits. The results show that functional leaf traits of the LES were also valid predictors for the parameters of stomatal regulation. For example, leaf carbon concentration was positively related to the vapor pressure deficit (vpd) at the point of inflection and the maximum of the conductance-vpd curve. However, traits that are not included in the LES added information in explaining parameters of stomatal control: the vpd at the point of inflection of the conductance-vpd curve was lower for species with higher stomatal density and higher stomatal index. Overall, stomata and vein traits were more powerful predictors for explaining stomatal regulation than traits used in the LES.

7 CFR 30.31 - Classification of leaf tobacco.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Classification of leaf tobacco. 30.31 Section 30.31... REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of Grades § 30.31 Classification of leaf tobacco. For the purpose of this classification leaf tobacco shall...

Biophysical control of leaf temperature

Science.gov (United States)

Dong, N.; Prentice, I. C.; Wright, I. J.

2014-12-01

In principle sunlit leaves can maintain their temperatures within a narrower range than ambient temperatures. This is an important and long-known (but now overlooked) prediction of energy balance theory. Net radiation at leaf surface in steady state (which is reached rapidly) must be equal to the combination of sensible and latent heat exchanges with surrounding air, the former being proportional to leaf-to-air temperature difference (ΔT), the latter to the transpiration rate. We present field measurements of ΔT which confirm the existence of a 'crossover temperature' in the 25-30˚C range for species in a tropical savanna and a tropical rainforest environment. This finding is consistent with a simple representation of transpiration as a function of net radiation and temperature (Priestley-Taylor relationship) assuming an entrainment factor (ω) somewhat greater than the canonical value of 0.26. The fact that leaves in tropical forests are typically cooler than surrounding air, often already by solar noon, is consistent with a recently published comparison of MODIS day-time land-surface temperatures with air temperatures. Theory further predicts a strong dependence of leaf size (which is inversely related to leaf boundary-layer conductance, and therefore to absolute magnitude of ΔT) on moisture availability. Theoretically, leaf size should be determined by either night-time constraints (risk of frost damage to active leaves) or day-time constraints (risk of heat stress damage),with the former likely to predominate - thereby restricting the occurrence of large leaves - at high latitudes. In low latitudes, daytime maximum leaf size is predicted to increase with temperature, provided that water is plentiful. If water is restricted, however, transpiration cannot proceed at the Priestley-Taylor rate, and it quickly becomes advantageous for plants to have small leaves, which do not heat up much above the temperature of their surroundings. The difference between leaf

Possible Roles of Strigolactones during Leaf Senescence

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Yusuke Yamada

2015-09-01

Full Text Available Leaf senescence is a complicated developmental process that involves degenerative changes and nutrient recycling. The progress of leaf senescence is controlled by various environmental cues and plant hormones, including ethylene, jasmonic acid, salicylic acid, abscisic acid, cytokinins, and strigolactones. The production of strigolactones is induced in response to nitrogen and phosphorous deficiency. Strigolactones also accelerate leaf senescence and regulate shoot branching and root architecture. Leaf senescence is actively promoted in a nutrient-poor soil environment, and nutrients are transported from old leaves to young tissues and seeds. Strigolactones might act as important signals in response to nutrient levels in the rhizosphere. In this review, we discuss the possible roles of strigolactones during leaf senescence.

Cotton leaf curl Burewala virus with intact or mutant transcriptional activator proteins: complexity of cotton leaf curl disease.

Science.gov (United States)

Kumar, Jitendra; Gunapati, Samatha; Alok, Anshu; Lalit, Adarsh; Gadre, Rekha; Sharma, Naresh C; Roy, Joy K; Singh, Sudhir P

2015-05-01

Cotton leaf curl disease (CLCuD) is a serious disease of cotton on the Indian subcontinent. In the present study, three cotton leaf curl viruses, cotton leaf curl Burewala virus (CLCuBuV), cotton leaf curl Kokhran virus (CLCuKoV) and cotton leaf curl Multan virus (CLCuMV), and their associated satellites, cotton leaf curl Multan betasatellite (CLCuMB) and cotton leaf curl Multan alphasatellite (CLCuMA), were detected. CLCuBuV with either intact (CLCuBuV-1) or mutant (CLCuBuV-2) transcriptional activator protein (TrAP) were detected in different plants. Agroinoculation with CLCuBuV-1 or CLCuBuV-2 together with CLCuMB and CLCuMA, resulted in typical leaf curling and stunting of tobacco plants. Inoculation with CLCuKoV or an isolate of CLCuMV (CLCuMV-2), together with CLCuMB and CLCuMA, induced severe leaf curling, while the other isolate of CLCuMV (CLCuMV-1), which was recombinant in origin, showed mild leaf curling in tobacco. To investigate the effect of intact or mutant TrAP and also the recombination events, CLCuBuV-1, CLCuBuV-2, CLCuMV-1 or CLCuMV-2 together with the satellites (CLCuMA and CLCuMB) were transferred to cotton via whitefly-mediated transmission. Cotton plants containing CLCuBuV-1, CLCuBuV-2 or CLCuMV-2 together with satellites showed curling and stunting, whereas the plants having CLCuMV-1 and the satellites showed only mild and indistinguishable symptoms. CLCuBuV-1 (intact TrAP) showed severe symptoms in comparison to CLCuBuV-2 (mutant TrAP). The present study reveals that two types of CLCuBuV, one with an intact TrAP and the other with a mutant TrAP, exist in natural infection of cotton in India. Additionally, CLCuMuV-1, which has a recombinant origin, induces mild symptoms in comparison to the other CLCuMV isolates.

syk kinase activation by a src kinase-initiated activation loop phosphorylation chain reaction

Science.gov (United States)

El-Hillal, O.; Kurosaki, T.; Yamamura, H.; Kinet, J.-P.; Scharenberg, A. M.

1997-01-01

Activation of the syk tyrosine kinase occurs almost immediately following engagement of many types of antigen receptors, including Fc receptors, but the mechanism through which syk is activated is currently unclear. Here we demonstrate that Fc receptor-induced syk activation occurs as the result of phosphorylation of the syk activation loop by both src family kinases and other molecules of activated syk, suggesting that syk activation occurs as the result of a src kinase-initiated activation loop phosphorylation chain reaction. This type of activation mechanism predicts that syk activation would exhibit exponential kinetics, providing a potential explanation for its rapid and robust activation by even weak antigen receptor stimuli. We propose that a similar mechanism may be responsible for generating rapid activation of other cytoplasmic tyrosine kinases, such as those of the Bruton tyrosine kinase/tec family, as well. PMID:9050880

Phosphoenolpyruvate carboxykinase in bovine tick Rhipicephalus (Boophilus) micro plus embryogenesis and starvation larvae

Energy Technology Data Exchange (ETDEWEB)

Andrade, J.G. de; Mentizingen, L.G.; Logullo, C. [Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Campos dos Goytacazes, RJ (Brazil). Centro de Biociencias e Biotecnologia. Lab.de Quimica e Funcao de Proteinas e Peptideos (LQFPP); Andrade, C.P. de; Vaz Junior, Itabajara [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Centro de Biotecnologia; Daffre, S.; Esteves, E. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Ciencias Biomedicas

2008-07-01

Full text: Phosphoenolpyruvate carboxykinase (PEPCK) is considered a key rate controlling enzyme in gluconeogenesis pathway. Gluconeogenesis is a highly regulated process, catalyzed by several enzymes subject to regulation by insulin. Normally, insulin rapidly and substantially inhibits PEPCK gene transcription and the PEPCK activity is proportional to the rate of gene transcription. The transcriptional regulation of the PEPCK gene has been extensively studied. CREM is the transcription factor that bind efficiently to the putative cyclic AMP response element (CRE) in PEPCK gene. Several other transcription factors can bind to this element and activate transcription. In oviparous animals, such as bovine tick R. microplus, the embryonic development occurs outside the maternal organism, implying that all the nutrients necessary for embryogenesis must be present in the oocytes. We observed the relationship between the main energy sources and the morphogenetic changes that occur during R. microplus tick embryogenesis. Energy homeostasis is maintained by glycogen mobilization in the beginning of embryogenesis, as its content is drastically decreased during the first five days of development. Afterwards, the activity of the gluconeogenesis enzyme PEPCK increases enormously, as indicated by a concomitant increase in glucose content (Moraes et al., 2007). Here, we analyzed PEPCK gene transcription by qPCR during the embryogenesis and starvation larvae. The PEPCK transcription was higher at first and 15th day eggs of the development. In larvae the levels of PEPCK transcripts is increased at fifth day after hatch. However, the activity is continuous increased in larvae the form first up to 15th day. Now we are investigating the involvement of CREM in the PEPCK gene transcription in these cells. In this sense, we obtained CREM sequence from TIGR ESTs R. microplus bank and designed the specific primers to qPCR. Taken together our results suggest the involvement of PEPCK to the

Phosphoenolpyruvate carboxykinase in bovine tick Rhipicephalus (Boophilus) micro plus embryogenesis and starvation larvae

International Nuclear Information System (INIS)

Andrade, J.G. de; Mentizingen, L.G.; Logullo, C.; Andrade, C.P. de; Vaz Junior, Itabajara; Daffre, S.; Esteves, E.

2008-01-01

Full text: Phosphoenolpyruvate carboxykinase (PEPCK) is considered a key rate controlling enzyme in gluconeogenesis pathway. Gluconeogenesis is a highly regulated process, catalyzed by several enzymes subject to regulation by insulin. Normally, insulin rapidly and substantially inhibits PEPCK gene transcription and the PEPCK activity is proportional to the rate of gene transcription. The transcriptional regulation of the PEPCK gene has been extensively studied. CREM is the transcription factor that bind efficiently to the putative cyclic AMP response element (CRE) in PEPCK gene. Several other transcription factors can bind to this element and activate transcription. In oviparous animals, such as bovine tick R. microplus, the embryonic development occurs outside the maternal organism, implying that all the nutrients necessary for embryogenesis must be present in the oocytes. We observed the relationship between the main energy sources and the morphogenetic changes that occur during R. microplus tick embryogenesis. Energy homeostasis is maintained by glycogen mobilization in the beginning of embryogenesis, as its content is drastically decreased during the first five days of development. Afterwards, the activity of the gluconeogenesis enzyme PEPCK increases enormously, as indicated by a concomitant increase in glucose content (Moraes et al., 2007). Here, we analyzed PEPCK gene transcription by qPCR during the embryogenesis and starvation larvae. The PEPCK transcription was higher at first and 15th day eggs of the development. In larvae the levels of PEPCK transcripts is increased at fifth day after hatch. However, the activity is continuous increased in larvae the form first up to 15th day. Now we are investigating the involvement of CREM in the PEPCK gene transcription in these cells. In this sense, we obtained CREM sequence from TIGR ESTs R. microplus bank and designed the specific primers to qPCR. Taken together our results suggest the involvement of PEPCK to the

Enhanced functional recombinant factor VII production by HEK 293 cells stably transfected with VKORC1 where the gamma-carboxylase inhibitor calumenin is stably suppressed by shRNA transfection.

Science.gov (United States)

Wajih, Nadeem; Owen, John; Wallin, Reidar

2008-01-01

Recombinant members of the vitamin K-dependent protein family (factors IX and VII and protein C) have become important pharmaceuticals in treatment of bleeding disorders and sepsis. However, because the in vivo gamma-carboxylation system in stable cell lines used for transfection has a limited capacity of post translational gamma-carboxylation, the recovery of fully gamma-carboxylated and functional proteins is low. In this work we have engineered recombinant factor VII producing HEK 293 cells to stably overexpress VKORC1, the reduced vitamin K gamma-carboxylase cofactor and in addition stably silenced the gamma-carboxylase inhibitory protein calumenin. Stable cell lines transfected with only a factor VII cDNA had a 9% production of functional recombinant factor VII. On the other hand, these recombinant factor VII producing cells when engineered to overexpress VKORC1 and having calumenin stably suppressed more than 80% by shRNA expression, produced 68% functional factor VII. The technology presented should be applicable to all vertebrae members of the vitamin K-dependent protein family and should lower the production cost of the clinically used factors VII, IX and protein C.

The plant leaf movement analyzer (PALMA): a simple tool for the analysis of periodic cotyledon and leaf movement in Arabidopsis thaliana.

Science.gov (United States)

Wagner, Lucas; Schmal, Christoph; Staiger, Dorothee; Danisman, Selahattin

2017-01-01

The analysis of circadian leaf movement rhythms is a simple yet effective method to study effects of treatments or gene mutations on the circadian clock of plants. Currently, leaf movements are analysed using time lapse photography and subsequent bioinformatics analyses of leaf movements. Programs that are used for this purpose either are able to perform one function (i.e. leaf tip detection or rhythm analysis) or their function is limited to specific computational environments. We developed a leaf movement analysis tool-PALMA-that works in command line and combines image extraction with rhythm analysis using Fast Fourier transformation and non-linear least squares fitting. We validated PALMA in both simulated time series and in experiments using the known short period mutant sensitivity to red light reduced 1 ( srr1 - 1 ). We compared PALMA with two established leaf movement analysis tools and found it to perform equally well. Finally, we tested the effect of reduced iron conditions on the leaf movement rhythms of wild type plants. Here, we found that PALMA successfully detected period lengthening under reduced iron conditions. PALMA correctly estimated the period of both simulated and real-life leaf movement experiments. As a platform-independent console-program that unites both functions needed for the analysis of circadian leaf movements it is a valid alternative to existing leaf movement analysis tools.

Effects of nitrogen application rate and leaf age on the distribution pattern of leaf SPAD readings in the rice canopy.

Directory of Open Access Journals (Sweden)

Hu Yang

Full Text Available A Soil-Plant Analysis Development (SPAD chlorophyll meter can be used as a simple tool for evaluating N concentration of the leaf and investigating the combined effects of nitrogen rate and leaf age on N distribution. We conducted experiments in a paddy field over two consecutive years (2008-2009 using rice plants treated with six different N application levels. N distribution pattern was determined by SPAD readings based on the temporal dynamics of N concentrations in individual leaves. At 62 days after transplantation (DAT in 2008 and DAT 60 in 2009, leaf SPAD readings increased from the upper to lower in the rice canopy that received N levels of 150 to 375 kg ha(-1The differences in SPAD readings between the upper and lower leaf were larger under higher N application rates. However, as plants grew, this atypical distribution of SPAD readings in canopy leaf quickly reversed to the general order. In addition, temporal dynamics of the leaf SPAD readings (N concentrations were fitted to a piecewise function. In our model, changes in leaf SPAD readings were divided into three stages: growth, functioning, and senescence periods. The leaf growth period lasted approximately 6 days, and cumulative growing days were not affected by N application rates. The leaf functioning period was represented with a relatively stable SPAD reading related to N application rate, and cumulative growing days were extended with increasing N application rates. A quadratic equation was utilized to describe the relationship between SPAD readings and leaf age during the leaf senescence period. The rate of decrease in SPAD readings increased with the age of leaves, but the rate was slowed by N application. As leaves in the lower canopy were physiologically older than leaves in the upper canopy, the rate of decrease in SPAD readings was faster in the lower leaves.

Receptor-interacting protein (RIP) kinase family

Science.gov (United States)

Zhang, Duanwu; Lin, Juan; Han, Jiahuai

2010-01-01

Receptor-interacting protein (RIP) kinases are a group of threonine/serine protein kinases with a relatively conserved kinase domain but distinct non-kinase regions. A number of different domain structures, such as death and caspase activation and recruitment domain (CARD) domains, were found in different RIP family members, and these domains should be keys in determining the specific function of each RIP kinase. It is known that RIP kinases participate in different biological processes, including those in innate immunity, but their downstream substrates are largely unknown. This review will give an overview of the structures and functions of RIP family members, and an update of recent progress in RIP kinase research. PMID:20383176

The human gastric pathogen Helicobacter pylori has a potential acetone carboxylase that enhances its ability to colonize mice

Directory of Open Access Journals (Sweden)

Weinberg Michael V

2008-01-01

Full Text Available Abstract Background Helicobacter pylori colonizes the human stomach and is the etiological agent of peptic ulcer disease. All three H. pylori strains that have been sequenced to date contain a potential operon whose products share homology with the subunits of acetone carboxylase (encoded by acxABC from Xanthobacter autotrophicus strain Py2 and Rhodobacter capsulatus strain B10. Acetone carboxylase catalyzes the conversion of acetone to acetoacetate. Genes upstream of the putative acxABC operon encode enzymes that convert acetoacetate to acetoacetyl-CoA, which is metabolized further to generate two molecules of acetyl-CoA. Results To determine if the H. pylori acxABC operon has a role in host colonization the acxB homolog in the mouse-adapted H. pylori SS1 strain was inactivated with a chloramphenicol-resistance (cat cassette. In mouse colonization studies the numbers of H. pylori recovered from mice inoculated with the acxB:cat mutant were generally one to two orders of magnitude lower than those recovered from mice inoculated with the parental strain. A statistical analysis of the data using a Wilcoxin Rank test indicated the differences in the numbers of H. pylori isolated from mice inoculated with the two strains were significant at the 99% confidence level. Levels of acetone associated with gastric tissue removed from uninfected mice were measured and found to range from 10–110 μmols per gram wet weight tissue. Conclusion The colonization defect of the acxB:cat mutant suggests a role for the acxABC operon in survival of the bacterium in the stomach. Products of the H. pylori acxABC operon may function primarily in acetone utilization or may catalyze a related reaction that is important for survival or growth in the host. H. pylori encounters significant levels of acetone in the stomach which it could use as a potential electron donor for microaerobic respiration.

A hairy-leaf gene, BLANKET LEAF, of wild Oryza nivara increases photosynthetic water use efficiency in rice.

Science.gov (United States)

Hamaoka, Norimitsu; Yasui, Hideshi; Yamagata, Yoshiyuki; Inoue, Yoko; Furuya, Naruto; Araki, Takuya; Ueno, Osamu; Yoshimura, Atsushi

2017-12-01

High water use efficiency is essential to water-saving cropping. Morphological traits that affect photosynthetic water use efficiency are not well known. We examined whether leaf hairiness improves photosynthetic water use efficiency in rice. A chromosome segment introgression line (IL-hairy) of wild Oryza nivara (Acc. IRGC105715) with the genetic background of Oryza sativa cultivar 'IR24' had high leaf pubescence (hair). The leaf hairs developed along small vascular bundles. Linkage analysis in BC 5 F 2 and F 3 populations showed that the trait was governed by a single gene, designated BLANKET LEAF (BKL), on chromosome 6. IL-hairy plants had a warmer leaf surface in sunlight, probably due to increased boundary layer resistance. They had a lower transpiration rate under moderate and high light intensities, resulting in higher photosynthetic water use efficiency. Introgression of BKL on chromosome 6 from O. nivara improved photosynthetic water use efficiency in the genetic background of IR24.

Regulation of the interaction between protein kinase C-related protein kinase 2 (PRK2) and its upstream kinase, 3-phosphoinositide-dependent protein kinase 1 (PDK1)

DEFF Research Database (Denmark)

Dettori, Rosalia; Sonzogni, Silvina; Meyer, Lucas

2009-01-01

of numerous AGC kinases, including the protein kinase C-related protein kinases (PRKs). Here we studied the docking interaction between PDK1 and PRK2 and analyzed the mechanisms that regulate this interaction. In vivo labeling of recombinant PRK2 by (32)P(i) revealed phosphorylation at two sites......, the activation loop and the Z/TM in the C-terminal extension. We provide evidence that phosphorylation of the Z/TM site of PRK2 inhibits its interaction with PDK1. Our studies further provide a mechanistic model to explain different steps in the docking interaction and regulation. Interestingly, we found...... that the mechanism that negatively regulates the docking interaction of PRK2 to the upstream kinase PDK1 is directly linked to the activation mechanism of PRK2 itself. Finally, our results indicate that the mechanisms underlying the regulation of the interaction between PRK2 and PDK1 are specific for PRK2 and do...

Understanding the molecular basis of plant growth promotional effect of Pseudomonas fluorescens on rice through protein profiling

Directory of Open Access Journals (Sweden)

Thiruvengadam Raguchander

2009-12-01

Full Text Available Abstract Background Plant Growth Promoting Rhizobacteria (PGPR, Pseudomonas fluorescens strain KH-1 was found to exhibit plant growth promotional activity in rice under both in-vitro and in-vivo conditions. But the mechanism underlying such promotional activity of P. fluorescens is not yet understood clearly. In this study, efforts were made to elucidate the molecular responses of rice plants to P. fluorescens treatment through protein profiling. Two-dimensional polyacrylamide gel electrophoresis strategy was adopted to identify the PGPR responsive proteins and the differentially expressed proteins were analyzed by mass spectrometry. Results Priming of P. fluorescens, 23 different proteins found to be differentially expressed in rice leaf sheaths and MS analysis revealed the differential expression of some important proteins namely putative p23 co-chaperone, Thioredoxin h- rice, Ribulose-bisphosphate carboxylase large chain precursor, Nucleotide diPhosphate kinase, Proteosome sub unit protein and putative glutathione S-transferase protein. Conclusion Functional analyses of the differential proteins were reported to be directly or indirectly involved in growth promotion in plants. Thus, this study confirms the primary role of PGPR strain KH-1 in rice plant growth promotion.

Seasonal patterns of leaf gas exchange and water relations in dry rain forest trees of contrasting leaf phenology.

Science.gov (United States)

Choat, Brendan; Ball, Marilyn C; Luly, Jon G; Donnelly, Christine F; Holtum, Joseph A M

2006-05-01

Diurnal and seasonal patterns of leaf gas exchange and water relations were examined in tree species of contrasting leaf phenology growing in a seasonally dry tropical rain forest in north-eastern Australia. Two drought-deciduous species, Brachychiton australis (Schott and Endl.) A. Terracc. and Cochlospermum gillivraei Benth., and two evergreen species, Alphitonia excelsa (Fenzal) Benth. and Austromyrtus bidwillii (Benth.) Burret. were studied. The deciduous species had higher specific leaf areas and maximum photosynthetic rates per leaf dry mass in the wet season than the evergreens. During the transition from wet season to dry season, total canopy area was reduced by 70-90% in the deciduous species and stomatal conductance (g(s)) and assimilation rate (A) were markedly lower in the remaining leaves. Deciduous species maintained daytime leaf water potentials (Psi(L)) at close to or above wet season values by a combination of stomatal regulation and reduction in leaf area. Thus, the timing of leaf drop in deciduous species was not associated with large negative values of daytime Psi(L) (greater than -1.6 MPa) or predawn Psi(L) (greater than -1.0 MPa). The deciduous species appeared sensitive to small perturbations in soil and leaf water status that signalled the onset of drought. The evergreen species were less sensitive to the onset of drought and g(s) values were not significantly lower during the transitional period. In the dry season, the evergreen species maintained their canopies despite increasing water-stress; however, unlike Eucalyptus species from northern Australian savannas, A and g(s) were significantly lower than wet season values.

Pyruvate carboxylase is required for glutamine-independent growth of tumor cells

Science.gov (United States)

Cheng, Tzuling; Sudderth, Jessica; Yang, Chendong; Mullen, Andrew R.; Jin, Eunsook S.; Matés, José M.; DeBerardinis, Ralph J.

2011-01-01

Tumor cells require a constant supply of macromolecular precursors, and interrupting this supply has been proposed as a therapeutic strategy in cancer. Precursors for lipids, nucleic acids, and proteins are generated in the tricarboxylic acid (TCA) cycle and removed from the mitochondria to participate in biosynthetic reactions. Refilling the pool of precursor molecules (anaplerosis) is therefore crucial to maintain cell growth. Many tumor cells use glutamine to feed anaplerosis. Here we studied how “glutamine-addicted” cells react to interruptions of glutamine metabolism. Silencing of glutaminase (GLS), which catalyzes the first step in glutamine-dependent anaplerosis, suppressed but did not eliminate the growth of glioblastoma cells in culture and in vivo. Profiling metabolic fluxes in GLS-suppressed cells revealed induction of a compensatory anaplerotic mechanism catalyzed by pyruvate carboxylase (PC), allowing the cells to use glucose-derived pyruvate rather than glutamine for anaplerosis. Although PC was dispensable when glutamine was available, forcing cells to adapt to low-glutamine conditions rendered them absolutely dependent on PC for growth. Furthermore, in other cell lines, measuring PC activity in nutrient-replete conditions predicted dependence on specific anaplerotic enzymes. Cells with high PC activity were resistant to GLS silencing and did not require glutamine for survival or growth, but displayed suppressed growth when PC was silenced. Thus, PC-mediated, glucose-dependent anaplerosis allows cells to achieve glutamine independence. Induction of PC during chronic suppression of glutamine metabolism may prove to be a mechanism of resistance to therapies targeting glutaminolysis. PMID:21555572

Leaf area index from litter collection: impact of specific leaf area variability within a beech stand

Energy Technology Data Exchange (ETDEWEB)

Bouriaud, O. [Inst. National de la Recherche Agronomique, Centre de Recherches Forestieres de Nancy, Champenoux (France); Soudani, K. [Univ. Paris-Sud XI, Dept. d' Ecophysiologie Vegetale, Lab. Ecologie Systematique et Evolution, Orsay Cedex (France); Breda, N. [Inst. National de la Recherche Agronomique, Centre de Recherches Forestieres de Nancy, Champenoux (France)

2003-06-01

Litter fall collection is a direct method widely used to estimate leaf area index (LAI) in broad-leaved forest stands. Indirect measurements using radiation transmittance and gap fraction theory are often compared and calibrated against litter fall, which is considered as a reference method, but few studies address the question of litter specific leaf area (SLA) measurement and variability. SLA (leaf area per unit of dry weight, m{sup 2}{center_dot}g{sup -1}) is used to convert dry leaf litter biomass (g .m{sup -}2) into leaf area per ground unit area (m{sup 2}{center_dot}m{sup -2}). We paid special attention to this parameter in two young beech stands (dense and thinned) in northeastern France. The variability of both canopy (closure, LAI) and site conditions (soil properties, vegetation) was investigated as potential contributing factors to beech SLA variability. A systematic description of soil and floristic composition was performed and three types of soil were identified. Ellenberg's indicator values were averaged for each plot to assess nitrogen soil content. SLA of beech litter was measured three times during the fall in 23 plots in the stands (40 ha). Litter was collected bimonthly in square-shaped traps (0.5 m{sup 2}) and dried. Before drying, 30 leaves per plot and for each date were sampled, and leaf length, width, and area were measured with the help of a LI-COR areameter. SLA was calculated as the ratio of cumulated leaf area to total dry weight of the 30 leaves. Leaves characteristics per plot were averaged for the three dates of litter collection. Plant area index (PAI), estimated using the LAI-2000 plant canopy analyser and considering only the upper three rings, ranged from 2.9 to 8.1. Specific leaf area of beech litter was also highly different from one plot to the other, ranging from 150 to 320 cm{sup 2}{center_dot}g{sup -1}. Nevertheless, no relationship was found between SLA and stand canopy closure or PAI On the contrary, a significant

Leaf area index from litter collection: impact of specific leaf area variability within a beech stand

International Nuclear Information System (INIS)

Bouriaud, O.; Soudani, K.; Breda, N.

2003-01-01

Litter fall collection is a direct method widely used to estimate leaf area index (LAI) in broad-leaved forest stands. Indirect measurements using radiation transmittance and gap fraction theory are often compared and calibrated against litter fall, which is considered as a reference method, but few studies address the question of litter specific leaf area (SLA) measurement and variability. SLA (leaf area per unit of dry weight, m 2 ·g -1 ) is used to convert dry leaf litter biomass (g .m - 2) into leaf area per ground unit area (m 2 ·m -2 ). We paid special attention to this parameter in two young beech stands (dense and thinned) in northeastern France. The variability of both canopy (closure, LAI) and site conditions (soil properties, vegetation) was investigated as potential contributing factors to beech SLA variability. A systematic description of soil and floristic composition was performed and three types of soil were identified. Ellenberg's indicator values were averaged for each plot to assess nitrogen soil content. SLA of beech litter was measured three times during the fall in 23 plots in the stands (40 ha). Litter was collected bimonthly in square-shaped traps (0.5 m 2 ) and dried. Before drying, 30 leaves per plot and for each date were sampled, and leaf length, width, and area were measured with the help of a LI-COR areameter. SLA was calculated as the ratio of cumulated leaf area to total dry weight of the 30 leaves. Leaves characteristics per plot were averaged for the three dates of litter collection. Plant area index (PAI), estimated using the LAI-2000 plant canopy analyser and considering only the upper three rings, ranged from 2.9 to 8.1. Specific leaf area of beech litter was also highly different from one plot to the other, ranging from 150 to 320 cm 2 ·g -1 . Nevertheless, no relationship was found between SLA and stand canopy closure or PAI On the contrary, a significant relationship between SLA and soil properties was observed. Both SLA

Effect of nitrogen supply on leaf growth, leaf nitrogen economy and photosynthetic capacity in potato

NARCIS (Netherlands)

Vos, J.; Putten, van der P.E.L.

1998-01-01

Literature reports show little effect of nitrogen supply on radiation use efficiency in potato and in other dicotyledonous C3 species. This paper tests the hypothesis that potato reduces leaf size rather than leaf nitrogen concentration and photosynthetic capacity when nitrogen is in short supply.

Role of an Essential Acyl Coenzyme A Carboxylase in the Primary and Secondary Metabolism of Streptomyces coelicolor A3(2)

Science.gov (United States)

Rodríguez, E.; Banchio, C.; Diacovich, L.; Bibb, M. J.; Gramajo, H.

2001-01-01

Two genes, accB and accE, that form part of the same operon, were cloned from Streptomyces coelicolor A3(2). AccB is homologous to the carboxyl transferase domain of several propionyl coezyme A (CoA) carboxylases and acyl-CoA carboxylases (ACCases) of actinomycete origin, while AccE shows no significant homology to any known protein. Expression of accB and accE in Escherichia coli and subsequent in vitro reconstitution of enzyme activity in the presence of the biotinylated protein AccA1 or AccA2 confirmed that AccB was the carboxyl transferase subunit of an ACCase. The additional presence of AccE considerably enhanced the activity of the enzyme complex, suggesting that this small polypeptide is a functional component of the ACCase. The impossibility of obtaining an accB null mutant and the thiostrepton growth dependency of a tipAp accB conditional mutant confirmed that AccB is essential for S. coelicolor viability. Normal growth phenotype in the absence of the inducer was restored in the conditional mutant by the addition of exogenous long-chain fatty acids in the medium, indicating that the inducer-dependent phenotype was specifically related to a conditional block in fatty acid biosynthesis. Thus, AccB, together with AccA2, which is also an essential protein (E. Rodriguez and H. Gramajo, Microbiology 143:3109–3119, 1999), are the most likely components of an ACCase whose main physiological role is the synthesis of malonyl-CoA, the first committed step of fatty acid synthesis. Although normal growth of the conditional mutant was restored by fatty acids, the cultures did not produce actinorhodin or undecylprodigiosin, suggesting a direct participation of this enzyme complex in the supply of malonyl-CoA for the synthesis of these secondary metabolites. PMID:11526020

Leaf extraction and analysis framework graphical user interface: segmenting and analyzing the structure of leaf veins and areoles.

Science.gov (United States)

Price, Charles A; Symonova, Olga; Mileyko, Yuriy; Hilley, Troy; Weitz, Joshua S

2011-01-01

Interest in the structure and function of physical biological networks has spurred the development of a number of theoretical models that predict optimal network structures across a broad array of taxonomic groups, from mammals to plants. In many cases, direct tests of predicted network structure are impossible given the lack of suitable empirical methods to quantify physical network geometry with sufficient scope and resolution. There is a long history of empirical methods to quantify the network structure of plants, from roots, to xylem networks in shoots and within leaves. However, with few exceptions, current methods emphasize the analysis of portions of, rather than entire networks. Here, we introduce the Leaf Extraction and Analysis Framework Graphical User Interface (LEAF GUI), a user-assisted software tool that facilitates improved empirical understanding of leaf network structure. LEAF GUI takes images of leaves where veins have been enhanced relative to the background, and following a series of interactive thresholding and cleaning steps, returns a suite of statistics and information on the structure of leaf venation networks and areoles. Metrics include the dimensions, position, and connectivity of all network veins, and the dimensions, shape, and position of the areoles they surround. Available for free download, the LEAF GUI software promises to facilitate improved understanding of the adaptive and ecological significance of leaf vein network structure.

Leaf Area Estimation Models for Ginger ( Zingibere officinale Rosc ...

African Journals Online (AJOL)

The study was carried out to develop leaf area estimation models for three cultivars (37/79, 38/79 and 180/73) and four accessions (29/86, 30/86, 47/86 and 52/86) of ginger. Significant variations were observed among the tested genotypes in leaf length (L), leaf width (W) and actual leaf area (ALA). Leaf area was highly ...

A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

Data.gov (United States)

National Aeronautics and Space Administration — ABSTRACT: This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax...

A Global Data Set of Leaf Photosynthetic Rates, Leaf N and P, and Specific Leaf Area

Data.gov (United States)

National Aeronautics and Space Administration — This global data set of photosynthetic rates and leaf nutrient traits was compiled from a comprehensive literature review. It includes estimates of Vcmax (maximum...

Does investment in leaf defenses drive changes in leaf economic strategy? A focus on whole-plant ontogeny.

Science.gov (United States)

Mason, Chase M; Donovan, Lisa A

2015-04-01

Leaf defenses have long been studied in the context of plant growth rate, resource availability, and optimal investment theory. Likewise, one of the central modern paradigms of plant ecophysiology, the leaf economics spectrum (LES), has been extensively studied in the context of these factors across ecological scales ranging from global species data sets to temporal shifts within individuals. Despite strong physiological links between LES strategy and leaf defenses in structure, function, and resource investment, the relationship between these trait classes has not been well explored. This study investigates the relationship between leaf defenses and LES strategy across whole-plant ontogeny in three diverse Helianthus species known to exhibit dramatic ontogenetic shifts in LES strategy, focusing primarily on physical and quantitative chemical defenses. Plants were grown under controlled environmental conditions and sampled for LES and defense traits at four ontogenetic stages. Defenses were found to shift strongly with ontogeny, and to correlate strongly with LES strategy. More advanced ontogenetic stages with more conservative LES strategy leaves had higher tannin activity and toughness in all species, and higher leaf dry matter content in two of three species. Modeling results in two species support the conclusion that changes in defenses drive changes in LES strategy through ontogeny, and in one species that changes in defenses and LES strategy are likely independently driven by ontogeny. Results of this study support the hypothesis that leaf-level allocation to defenses might be an important determinant of leaf economic traits, where high investment in defenses drives a conservative LES strategy.

Purification and characterization of a casein kinase 2-type protein kinase from pea nuclei

Science.gov (United States)

Li, H.; Roux, S. J.

1992-01-01

Almost all the polyamine-stimulated protein kinase activity associated with the chromatin fraction of nuclei purified from etiolated pea (Pisum sativum L.) plumules is present in a single enzyme that can be extracted from chromatin by 0.35 molar NaCl. This protein kinase can be further purified over 2000-fold by salt fractionation and anion-exchange and casein-agarose column chromatography, after which it is more than 90% pure. The purified kinase has a specific activity of about 650 nanomoles per minute per milligram protein in the absence of polyamines, with either ATP or GTP as phosphoryl donor. Spermidine can stimulate its activity fourfold, with half-maximal activation at about 2 millimolar. Spermine and putrescine also stimulate activity, although somewhat less effectively. This kinase has a tetrameric alpha 2 beta 2 structure with a native molecular weight of 130,000, and subunit molecular weights of 36,000 for the catalytic subunit (alpha) and 29,000 for the regulatory subunit (beta). In western blot analyses, only the alpha subunit reacts strongly with polyclonal antibodies to a Drosophila casein kinase II. The pea kinase can use casein and phosvitin as artificial substrates, phosphorylating both the serine and threonine residues of casein. It has a pH optimum near 8.0, a Vmax of 1.5 micromoles per minute per milligram protein, and a Km for ATP of approximately 75 micromolar. Its activity can be almost completely inhibited by heparin at 5 micrograms per milliliter, but is relatively insensitive to concentrations of staurosporine, K252a, and chlorpromazine that strongly antagonize Ca(2+) -regulated protein kinases. These results are discussed in relation to recent findings that casein kinase 2-type kinases may phosphorylate trans-acting factors that bind to light-regulated promoters in plants.

Photoperiodism and enzyme activity: towards a model for the control of circadian metabolic rhythms in the crassulacean Acid metabolism.

Science.gov (United States)

Queiroz, O; Morel, C

1974-04-01

Metabolic readjustments after a change from long days to short days appear, in Kalanchoe blossfeldiana, to be achieved through the operation of two main mechanisms: variation in enzyme capacity, and circadian rhythmicity. After a lag time, capacity in phosphoenolpyruvate carboxylase and capacity in aspartate aminotransferase increase exponentially and appear to be allometrically linked during 50 to 60 short days; then a sudden fall takes place in the activity of the former. Malic enzyme and alanine aminotransferase behave differently. Thus, the operation of the two sections of the pathway (before and after the malate step) give rise to a continuously changing functional compartmentation in the pathway. Circadian rhythmicity, on the other hand, produces time compartmentation through phase shifts and variation in amplitude, independently for each enzyme. These characteristics suggest that the operation of a so-called biological clock would be involved. We propose the hypothesis that feedback regulation would be more accurate and efficient when applied to an already oscillating, clock-controlled enzyme system.

Identification of multiple PEPC isogenes in leaves of the facultative Crassulacean acid metabolism (CAM) plant Kalanchoe blossfeldiana Poelln. cv. Tom Thumb.

Science.gov (United States)

Gehrig, H; Taybi, T; Kluge, M; Brulfert, J

1995-12-27

In the facultative Crassulacean Acid Metabolism (CAM) plant Kulanchoe blossfeldiana cv. Tom Thumb, CAM can be induced by short-day treatment or water deficiency stress. From young leaves of well-watered and water-stressed individuals of this plant, cDNA clones coding for a partial sequence of the key enzyme of CAM, phosphoenolpyruvate carboxylase, were isolated after transcription of mRNA. cDNA polymorphism was established by enzyme restriction profiles and sequencing data. Four PEPC isogenes could be shown to exist in K. blossfeldiana forming two gene pairs, with 95%-98% homology inside and only 75% between the pairs. One cDNA sequence pair having a length of 1113 bp and an open reading frame of 371 AA was identified as PEPC isoform specific for the C3 state, whereas the pair having a length of 1116 bp and an open reading frame of 372 AA could be attributed to the CAM state. These results were confirmed by Southern Blot hybridization.

Photoperiodism and Enzyme Activity

Science.gov (United States)

Queiroz, Orlando; Morel, Claudine

1974-01-01

Metabolic readjustments after a change from long days to short days appear, in Kalanchoe blossfeldiana, to be achieved through the operation of two main mechanisms: variation in enzyme capacity, and circadian rhythmicity. After a lag time, capacity in phosphoenolpyruvate carboxylase and capacity in aspartate aminotransferase increase exponentially and appear to be allometrically linked during 50 to 60 short days; then a sudden fall takes place in the activity of the former. Malic enzyme and alanine aminotransferase behave differently. Thus, the operation of the two sections of the pathway (before and after the malate step) give rise to a continuously changing functional compartmentation in the pathway. Circadian rhythmicity, on the other hand, produces time compartmentation through phase shifts and variation in amplitude, independently for each enzyme. These characteristics suggest that the operation of a so-called biological clock would be involved. We propose the hypothesis that feedback regulation would be more accurate and efficient when applied to an already oscillating, clock-controlled enzyme system. PMID:16658749

Influence of Vegetation Structure on Lidar-derived Canopy Height and Fractional Cover in Forested Riparian Buffers During Leaf-Off and Leaf-On Conditions

Science.gov (United States)

Wasser, Leah; Day, Rick; Chasmer, Laura; Taylor, Alan

2013-01-01

Estimates of canopy height (H) and fractional canopy cover (FC) derived from lidar data collected during leaf-on and leaf-off conditions are compared with field measurements from 80 forested riparian buffer plots. The purpose is to determine if existing lidar data flown in leaf-off conditions for applications such as terrain mapping can effectively estimate forested riparian buffer H and FC within a range of riparian vegetation types. Results illustrate that: 1) leaf-off and leaf-on lidar percentile estimates are similar to measured heights in all plots except those dominated by deciduous compound-leaved trees where lidar underestimates H during leaf off periods; 2) canopy height models (CHMs) underestimate H by a larger margin compared to percentile methods and are influenced by vegetation type (conifer needle, deciduous simple leaf or deciduous compound leaf) and canopy height variability, 3) lidar estimates of FC are within 10% of plot measurements during leaf-on periods, but are underestimated during leaf-off periods except in mixed and conifer plots; and 4) depth of laser pulse penetration lower in the canopy is more variable compared to top of the canopy penetration which may influence within canopy vegetation structure estimates. This study demonstrates that leaf-off lidar data can be used to estimate forested riparian buffer canopy height within diverse vegetation conditions and fractional canopy cover within mixed and conifer forests when leaf-on lidar data are not available. PMID:23382966

Leaf structural characteristics are less important than leaf chemical properties in determining the response of leaf mass per area and photosynthesis of Eucalyptus saligna to industrial-age changes in [CO2] and temperature.

Science.gov (United States)

Xu, Cheng-Yuan; Salih, Anya; Ghannoum, Oula; Tissue, David T

2012-10-01

The rise in atmospheric [CO(2)] is associated with increasing air temperature. However, studies on plant responses to interactive effects of [CO(2)] and temperature are limited, particularly for leaf structural attributes. In this study, Eucalyptus saligna plants were grown in sun-lit glasshouses differing in [CO(2)] (290, 400, and 650 µmol mol(-1)) and temperature (26 °C and 30 °C). Leaf anatomy and chloroplast parameters were assessed with three-dimensional confocal microscopy, and the interactive effects of [CO(2)] and temperature were quantified. The relative influence of leaf structural attributes and chemical properties on the variation of leaf mass per area (LMA) and photosynthesis within these climate regimes was also determined. Leaf thickness and mesophyll size increased in higher [CO(2)] but decreased at the warmer temperature; no treatment interaction was observed. In pre-industrial [CO(2)], warming reduced chloroplast diameter without altering chloroplast number per cell, but the opposite pattern (reduced chloroplast number per cell and unchanged chloroplast diameter) was observed in both current and projected [CO(2)]. The variation of LMA was primarily explained by total non-structural carbohydrate (TNC) concentration rather than leaf thickness. Leaf photosynthetic capacity (light- and [CO(2)]-saturated rate at 28 °C) and light-saturated photosynthesis (under growth [CO(2)] and temperature) were primarily determined by leaf nitrogen contents, while secondarily affected by chloroplast gas exchange surface area and chloroplast number per cell, respectively. In conclusion, leaf structural attributes are less important than TNC and nitrogen in affecting LMA and photosynthesis responses to the studied climate regimes, indicating that leaf structural attributes have limited capacity to adjust these functional traits in a changing climate.

Cocoa Procyanidins Suppress Transformation by Inhibiting Mitogen-activated Protein Kinase Kinase*S⃞

Science.gov (United States)

Kang, Nam Joo; Lee, Ki Won; Lee, Dong Eun; Rogozin, Evgeny A.; Bode, Ann M.; Lee, Hyong Joo; Dong, Zigang

2008-01-01

Cocoa was shown to inhibit chemically induced carcinogenesis in animals and exert antioxidant activity in humans. However, the molecular mechanisms of the chemopreventive potential of cocoa and its active ingredient(s) remain unknown. Here we report that cocoa procyanidins inhibit neoplastic cell transformation by suppressing the kinase activity of mitogen-activated protein kinase kinase (MEK). A cocoa procyanidin fraction (CPF) and procyanidin B2 at 5 μg/ml and 40 μm, respectively, inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced neoplastic transformation of JB6 P+ mouse epidermal (JB6 P+) cells by 47 and 93%, respectively. The TPA-induced promoter activity and expression of cyclooxygenase-2, which is involved in tumor promotion and inflammation, were dose-dependently inhibited by CPF or procyanidin B2. The activation of activator protein-1 and nuclear factor-κB induced by TPA was also attenuated by CPF or procyanidin B2. The TPA-induced phosphorylation of MEK, extracellular signal-regulated kinase, and p90 ribosomal s6 kinase was suppressed by CPF or procyanidin B2. In vitro and ex vivo kinase assay data demonstrated that CPF or procyanidin B2 inhibited the kinase activity of MEK1 and directly bound with MEK1. CPF or procyanidin B2 suppressed JB6 P+ cell transformation induced by epidermal growth factor or H-Ras, both of which are known to be involved in MEK/ERK signal activation. In contrast, theobromine (up to 80 μm) had no effect on TPA-induced transformation, cyclooxygenase-2 expression, the transactivation of activator protein-1 or nuclear factor-κB, or MEK. Notably, procyanidin B2 exerted stronger inhibitory effects compared with PD098059 (a well known pharmacological inhibitor of MEK) on MEK1 activity and neoplastic cell transformation. PMID:18519570

Identifying kinase dependency in cancer cells by integrating high-throughput drug screening and kinase inhibition data.

Science.gov (United States)

Ryall, Karen A; Shin, Jimin; Yoo, Minjae; Hinz, Trista K; Kim, Jihye; Kang, Jaewoo; Heasley, Lynn E; Tan, Aik Choon

2015-12-01

Targeted kinase inhibitors have dramatically improved cancer treatment, but kinase dependency for an individual patient or cancer cell can be challenging to predict. Kinase dependency does not always correspond with gene expression and mutation status. High-throughput drug screens are powerful tools for determining kinase dependency, but drug polypharmacology can make results difficult to interpret. We developed Kinase Addiction Ranker (KAR), an algorithm that integrates high-throughput drug screening data, comprehensive kinase inhibition data and gene expression profiles to identify kinase dependency in cancer cells. We applied KAR to predict kinase dependency of 21 lung cancer cell lines and 151 leukemia patient samples using published datasets. We experimentally validated KAR predictions of FGFR and MTOR dependence in lung cancer cell line H1581, showing synergistic reduction in proliferation after combining ponatinib and AZD8055. KAR can be downloaded as a Python function or a MATLAB script along with example inputs and outputs at: http://tanlab.ucdenver.edu/KAR/. aikchoon.tan@ucdenver.edu. Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Dependence of fluence errors in dynamic IMRT on leaf-positional errors varying with time and leaf number

International Nuclear Information System (INIS)

Zygmanski, Piotr; Kung, Jong H.; Jiang, Steve B.; Chin, Lee

2003-01-01

In d-MLC based IMRT, leaves move along a trajectory that lies within a user-defined tolerance (TOL) about the ideal trajectory specified in a d-MLC sequence file. The MLC controller measures leaf positions multiple times per second and corrects them if they deviate from ideal positions by a value greater than TOL. The magnitude of leaf-positional errors resulting from finite mechanical precision depends on the performance of the MLC motors executing leaf motions and is generally larger if leaves are forced to move at higher speeds. The maximum value of leaf-positional errors can be limited by decreasing TOL. However, due to the inherent time delay in the MLC controller, this may not happen at all times. Furthermore, decreasing the leaf tolerance results in a larger number of beam hold-offs, which, in turn leads, to a longer delivery time and, paradoxically, to higher chances of leaf-positional errors (≤TOL). On the other end, the magnitude of leaf-positional errors depends on the complexity of the fluence map to be delivered. Recently, it has been shown that it is possible to determine the actual distribution of leaf-positional errors either by the imaging of moving MLC apertures with a digital imager or by analysis of a MLC log file saved by a MLC controller. This leads next to an important question: What is the relation between the distribution of leaf-positional errors and fluence errors. In this work, we introduce an analytical method to determine this relation in dynamic IMRT delivery. We model MLC errors as Random-Leaf Positional (RLP) errors described by a truncated normal distribution defined by two characteristic parameters: a standard deviation σ and a cut-off value Δx 0 (Δx 0 ∼TOL). We quantify fluence errors for two cases: (i) Δx 0 >>σ (unrestricted normal distribution) and (ii) Δx 0 0 --limited normal distribution). We show that an average fluence error of an IMRT field is proportional to (i) σ/ALPO and (ii) Δx 0 /ALPO, respectively, where

Acetic acid activates the AMP-activated protein kinase signaling pathway to regulate lipid metabolism in bovine hepatocytes.

Directory of Open Access Journals (Sweden)

Xinwei Li

Full Text Available The effect of acetic acid on hepatic lipid metabolism in ruminants differs significantly from that in monogastric animals. Therefore, the aim of this study was to investigate the regulation mechanism of acetic acid on the hepatic lipid metabolism in dairy cows. The AMP-activated protein kinase (AMPK signaling pathway plays a key role in regulating hepatic lipid metabolism. In vitro, bovine hepatocytes were cultured and treated with different concentrations of sodium acetate (neutralized acetic acid and BML-275 (an AMPKα inhibitor. Acetic acid consumed a large amount of ATP, resulting in an increase in AMPKα phosphorylation. The increase in AMPKα phosphorylation increased the expression and transcriptional activity of peroxisome proliferator-activated receptor α, which upregulated the expression of lipid oxidation genes, thereby increasing lipid oxidation in bovine hepatocytes. Furthermore, elevated AMPKα phosphorylation reduced the expression and transcriptional activity of the sterol regulatory element-binding protein 1c and the carbohydrate responsive element-binding protein, which reduced the expression of lipogenic genes, thereby decreasing lipid biosynthesis in bovine hepatocytes. In addition, activated AMPKα inhibited the activity of acetyl-CoA carboxylase. Consequently, the triglyceride content in the acetate-treated hepatocytes was significantly decreased. These results indicate that acetic acid activates the AMPKα signaling pathway to increase lipid oxidation and decrease lipid synthesis in bovine hepatocytes, thereby reducing liver fat accumulation in dairy cows.

Control of biotin biosynthesis in mycobacteria by a pyruvate carboxylase dependent metabolic signal.

Science.gov (United States)

Lazar, Nathaniel; Fay, Allison; Nandakumar, Madhumitha; Boyle, Kerry E; Xavier, Joao; Rhee, Kyu; Glickman, Michael S

2017-12-01

Biotin is an essential cofactor utilized by all domains of life, but only synthesized by bacteria, fungi and plants, making biotin biosynthesis a target for antimicrobial development. To understand biotin biosynthesis in mycobacteria, we executed a genetic screen in Mycobacterium smegmatis for biotin auxotrophs and identified pyruvate carboxylase (Pyc) as required for biotin biosynthesis. The biotin auxotrophy of the pyc::tn strain is due to failure to transcriptionally induce late stage biotin biosynthetic genes in low biotin conditions. Loss of bioQ, the repressor of biotin biosynthesis, in the pyc::tn strain reverted biotin auxotrophy, as did reconstituting the last step of the pathway through heterologous expression of BioB and provision of its substrate DTB. The role of Pyc in biotin regulation required its catalytic activities and could be supported by M. tuberculosis Pyc. Quantitation of the kinetics of depletion of biotinylated proteins after biotin withdrawal revealed that Pyc is the most rapidly depleted biotinylated protein and metabolomics revealed a broad metabolic shift in wild type cells upon biotin withdrawal which was blunted in cell lacking Pyc. Our data indicate that mycobacterial cells monitor biotin sufficiency through a metabolic signal generated by dysfunction of a biotinylated protein of central metabolism. © 2017 John Wiley & Sons Ltd.

Src kinase regulation by phosphorylation and dephosphorylation

International Nuclear Information System (INIS)

Roskoski, Robert

2005-01-01

Src and Src-family protein-tyrosine kinases are regulatory proteins that play key roles in cell differentiation, motility, proliferation, and survival. The initially described phosphorylation sites of Src include an activating phosphotyrosine 416 that results from autophosphorylation, and an inhibiting phosphotyrosine 527 that results from phosphorylation by C-terminal Src kinase (Csk) and Csk homologous kinase. Dephosphorylation of phosphotyrosine 527 increases Src kinase activity. Candidate phosphotyrosine 527 phosphatases include cytoplasmic PTP1B, Shp1 and Shp2, and transmembrane enzymes include CD45, PTPα, PTPε, and PTPλ. Dephosphorylation of phosphotyrosine 416 decreases Src kinase activity. Thus far PTP-BL, the mouse homologue of human PTP-BAS, has been shown to dephosphorylate phosphotyrosine 416 in a regulatory fashion. The platelet-derived growth factor receptor protein-tyrosine kinase mediates the phosphorylation of Src Tyr138; this phosphorylation has no direct effect on Src kinase activity. The platelet-derived growth factor receptor and the ErbB2/HER2 growth factor receptor protein-tyrosine kinases mediate the phosphorylation of Src Tyr213 and activation of Src kinase activity. Src kinase is also a substrate for protein-serine/threonine kinases including protein kinase C (Ser12), protein kinase A (Ser17), and CDK1/cdc2 (Thr34, Thr46, and Ser72). Of the three protein-serine/threonine kinases, only phosphorylation by CDK1/cdc2 has been demonstrated to increase Src kinase activity. Although considerable information on the phosphoprotein phosphatases that catalyze the hydrolysis of Src phosphotyrosine 527 is at hand, the nature of the phosphatases that mediate the hydrolysis of phosphotyrosine 138 and 213, and phosphoserine and phosphothreonine residues has not been determined

Phenobarbital reduces blood glucose and gluconeogenesis through down-regulation of phosphoenolpyruvate carboxykinase (GTP) gene expression in rats.

Science.gov (United States)

Oda, Hiroaki; Okuda, Yuji; Yoshida, Yukiko; Kimura, Noriko; Kakinuma, Atsushi

2015-10-23

The regulatory mechanism of phosphoenolpyruvate carboykinase (GTP) (EC 4.1.1.32) (PEPCK) gene expression and gluconeogenesis by phenobarbital (PB), which is known to induce drug-metabolizing enzymes, was investigated. Higher level of PEPCK mRNA was observed in spherical rat primary hepatocytes on EHS-gel than monolayer hepatocytes on TIC (type I collagen). We found that PB directly suppressed PEPCK gene expression in spherical hepatocytes on EHS-gel, but not in those on TIC. PB strongly suppressed cAMP-dependent induction of PEPCK gene expression. Tyrosine aminotransferase (TAT), another gluconeogenic enzyme, was induced by cAMP, but not suppressed by PB. Chronic administration of PB reduced hepatic PEPCK mRNA in streptozotocin-induced diabetic and nondiabetic rats, and PB reduced blood glucose level in diabetic rats. Increased TAT mRNA in diabetic rats was not suppressed by PB. These results indicated that PB-dependent reduction is specific to PEPCK. From pyrvate challenge test, PB suppressed the increased gluconeogenesis in diabetic rats. PEPCK gene promoter activity was suppressed by PB in HepG2 cells. In conclusion, we found that spherical hepatocytes cultured on EHS-gel are capable to respond to PB to suppress PEPCK gene expression. Moreover, our results indicate that hypoglycemic action of PB result from transcriptional repression of PEPCK gene and subsequent suppression of gluconeogenesis. Copyright © 2015. Published by Elsevier Inc.

Cloning and expression analysis of carboxyltransferase of acetyl-coA carboxylase from Jatropha curcas.

Science.gov (United States)

Xie, Wu-Wei; Gao, Shun; Wang, Sheng-Hua; Zhu, Jin-Qiu; Xu, Ying; Tang, Lin; Chen, Fang

2010-01-01

A full-length cDNA of the carboxyltransferase (accA) gene of acetyl-coenzym A (acetyl-CoA) carboxylase from Jatropha curcas was cloned and sequenced. The gene with an open reading frame (ORF) of 1149 bp encodes a polypeptide of 383 amino acids, with a molecular mass of 41.9 kDa. Utilizing fluorogenic real-time polymerase chain reaction (RT-PCR), the expression levels of the accA gene in leaves and fruits at early, middle and late stages under pH 7.0/8.0 and light/darkness stress were investigated. The expression levels of the accA gene in leaves at early, middle and late stages increased significantly under pH 8.0 stress compared to pH 7.0. Similarly, the expression levels in fruits showed a significant increase under darkness condition compared to the control. Under light stress, the expression levels in the fruits at early, middle and late stages showed the largest fluctuations compared to those of the control. These findings suggested that the expression levels of the accA gene are closely related to the growth conditions and developmental stages in the leaves and fruits of Jatropha curcas.

The Nissan LEAF electric powertrain

Energy Technology Data Exchange (ETDEWEB)

Nakazawa, Shinsuke [Nissan Motor Co., Ltd. (Japan)

2011-07-01

The need for CO{sub 2} reduction as a countermeasure to global warming, and to move away from our dependence on fossil fuels as a countermeasure to energy security are urgent issues. One of the ultimate goals to achieving these targets is to develop a 'Zero emission car' such as an electric vehicle or a fuel cell vehicle, along with the manufacturing of clean energy. Nissan have developed a new powertrain for the electric vehicle, and have installed it in the Nissan LEAF. Sales of the Nissan LEAF started in North America, Europe and Japan in 2010, with plans to sell it globally by 2012. In order to achieve an improved driving range, power performance and drivability performance, Nissan have adapted a high efficiency synchronous motor, a water-cooled inverter, and reducer. Moreover, the Nissan LEAF has the capability of a 3.3kW AC charge and a 50kW DC quick charge. This presentation will introduce the features of the electric powertrain adopted for Nissan LEAF. (orig.)

A non-destructive method for estimating onion leaf area

Directory of Open Access Journals (Sweden)

Córcoles J.I.

2015-06-01

Full Text Available Leaf area is one of the most important parameters for characterizing crop growth and development, and its measurement is useful for examining the effects of agronomic management on crop production. It is related to interception of radiation, photosynthesis, biomass accumulation, transpiration and gas exchange in crop canopies. Several direct and indirect methods have been developed for determining leaf area. The aim of this study is to develop an indirect method, based on the use of a mathematical model, to compute leaf area in an onion crop using non-destructive measurements with the condition that the model must be practical and useful as a Decision Support System tool to improve crop management. A field experiment was conducted in a 4.75 ha commercial onion plot irrigated with a centre pivot system in Aguas Nuevas (Albacete, Spain, during the 2010 irrigation season. To determine onion crop leaf area in the laboratory, the crop was sampled on four occasions between 15 June and 15 September. At each sampling event, eight experimental plots of 1 m2 were used and the leaf area for individual leaves was computed using two indirect methods, one based on the use of an automated infrared imaging system, LI-COR-3100C, and the other using a digital scanner EPSON GT-8000, obtaining several images that were processed using Image J v 1.43 software. A total of 1146 leaves were used. Before measuring the leaf area, 25 parameters related to leaf length and width were determined for each leaf. The combined application of principal components analysis and cluster analysis for grouping leaf parameters was used to reduce the number of variables from 25 to 12. The parameter derived from the product of the total leaf length (L and the leaf diameter at a distance of 25% of the total leaf length (A25 gave the best results for estimating leaf area using a simple linear regression model. The model obtained was useful for computing leaf area using a non

Modeling canopy-level productivity: is the "big-leaf" simplification acceptable?

Science.gov (United States)

Sprintsin, M.; Chen, J. M.

2009-05-01

The "big-leaf" approach to calculating the carbon balance of plant canopies assumes that canopy carbon fluxes have the same relative responses to the environment as any single unshaded leaf in the upper canopy. Widely used light use efficiency models are essentially simplified versions of the big-leaf model. Despite its wide acceptance, subsequent developments in the modeling of leaf photosynthesis and measurements of canopy physiology have brought into question the assumptions behind this approach showing that big leaf approximation is inadequate for simulating canopy photosynthesis because of the additional leaf internal control on carbon assimilation and because of the non-linear response of photosynthesis on leaf nitrogen and absorbed light, and changes in leaf microenvironment with canopy depth. To avoid this problem a sunlit/shaded leaf separation approach, within which the vegetation is treated as two big leaves under different illumination conditions, is gradually replacing the "big-leaf" strategy, for applications at local and regional scales. Such separation is now widely accepted as a more accurate and physiologically based approach for modeling canopy photosynthesis. Here we compare both strategies for Gross Primary Production (GPP) modeling using the Boreal Ecosystem Productivity Simulator (BEPS) at local (tower footprint) scale for different land cover types spread over North America: two broadleaf forests (Harvard, Massachusetts and Missouri Ozark, Missouri); two coniferous forests (Howland, Maine and Old Black Spruce, Saskatchewan); Lost Creek shrubland site (Wisconsin) and Mer Bleue petland (Ontario). BEPS calculates carbon fixation by scaling Farquhar's leaf biochemical model up to canopy level with stomatal conductance estimated by a modified version of the Ball-Woodrow-Berry model. The "big-leaf" approach was parameterized using derived leaf level parameters scaled up to canopy level by means of Leaf Area Index. The influence of sunlit

Baby leaf lettuce germplasm enhancement: developing diverse populations with resistance to bacterial leaf spot caused by Xanthomonas campestris pv. vitians

Science.gov (United States)

Baby leaf lettuce cultivars with resistance to bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vitians (Xcv) are needed to reduce crop losses. The objectives of this research were to assess the genetic diversity for BLS resistance in baby leaf lettuce cultivars and to select early gen...

Leaf turgor loss point is correlated with drought tolerance and leaf carbon economics traits.

Science.gov (United States)

Zhu, Shi-Dan; Chen, Ya-Jun; Ye, Qing; He, Peng-Cheng; Liu, Hui; Li, Rong-Hua; Fu, Pei-Li; Jiang, Guo-Feng; Cao, Kun-Fang

2018-05-01

Leaf turgor loss point (πtlp) indicates the capacity of a plant to maintain cell turgor pressure during dehydration, which has been proven to be strongly predictive of the plant response to drought. In this study, we compiled a data set of πtlp for 1752 woody plant individuals belonging to 389 species from nine major woody biomes in China, along with reduced sample size of hydraulic and leaf carbon economics data. We aimed to investigate the variation of πtlp across biomes varying in water availability. We also tested two hypotheses: (i) πtlp predicts leaf hydraulic safety margins and (ii) it is correlated with leaf carbon economics traits. Our results showed that there was a positive relationship between πtlp and aridity index: biomes from humid regions had less negative values than those from arid regions. This supports the idea that πtlp may reflect drought tolerance at the scale of woody biomes. As expected, πtlp was significantly positively correlated with leaf hydraulic safety margins that varied significantly across biomes, indicating that this trait may be useful in modelling changes of forest components in response to increasing drought. Moreover, πtlp was correlated with a suite of coordinated hydraulic and economics traits; therefore, it can be used to predict the position of a given species along the 'fast-slow' whole-plant economics spectrum. This study expands our understanding of the biological significance of πtlp not only in drought tolerance, but also in the plant economics spectrum.

Structure-function similarities between a plant receptor-like kinase and the human interleukin-1 receptor-associated kinase-4.

Science.gov (United States)

Klaus-Heisen, Dörte; Nurisso, Alessandra; Pietraszewska-Bogiel, Anna; Mbengue, Malick; Camut, Sylvie; Timmers, Ton; Pichereaux, Carole; Rossignol, Michel; Gadella, Theodorus W J; Imberty, Anne; Lefebvre, Benoit; Cullimore, Julie V

2011-04-01

Phylogenetic analysis has previously shown that plant receptor-like kinases (RLKs) are monophyletic with respect to the kinase domain and share an evolutionary origin with the animal interleukin-1 receptor-associated kinase/Pelle-soluble kinases. The lysin motif domain-containing receptor-like kinase-3 (LYK3) of the legume Medicago truncatula shows 33% amino acid sequence identity with human IRAK-4 over the kinase domain. Using the structure of this animal kinase as a template, homology modeling revealed that the plant RLK contains structural features particular to this group of kinases, including the tyrosine gatekeeper and the N-terminal extension α-helix B. Functional analysis revealed the importance of these conserved features for kinase activity and suggests that kinase activity is essential for the biological role of LYK3 in the establishment of the root nodule nitrogen-fixing symbiosis with rhizobia bacteria. The kinase domain of LYK3 has dual serine/threonine and tyrosine specificity, and mass spectrometry analysis identified seven serine, eight threonine, and one tyrosine residue as autophosphorylation sites in vitro. Three activation loop serine/threonine residues are required for biological activity, and molecular dynamics simulations suggest that Thr-475 is the prototypical phosphorylated residue that interacts with the conserved arginine in the catalytic loop, whereas Ser-471 and Thr-472 may be secondary sites. A threonine in the juxtamembrane region and two threonines in the C-terminal lobe of the kinase domain are important for biological but not kinase activity. We present evidence that the structure-function similarities that we have identified between LYK3 and IRAK-4 may be more widely applicable to plant RLKs in general.

C-4 plants use fluctuating light less efficiently than do C-3 plants: a study of growth, photosynthesis and carbon isotope discrimination

Czech Academy of Sciences Publication Activity Database

Kubásek, Jiří; Urban, Otmar; Šantrůček, Jiří

2013-01-01

Roč. 149, č. 4 (2013), s. 528-539 ISSN 0031-9317 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073; GA ČR(CZ) GAP501/12/1261 Institutional support: RVO:67179843 ; RVO:60077344 Keywords : bundel-sheath leakiness * agrass genus muhlebergia * phosphenolpyruvate carboxylase * CO2 uptake * leaves * induction * sunflecks * responses * leaf Subject RIV: EH - Ecology, Behaviour; BO - Biophysics (BC-A) Impact factor: 3.262, year: 2013

7 CFR 29.3528 - Leaf surface.

Science.gov (United States)

2010-01-01

... INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf...

Converging Light, Energy and Hormonal Signaling Control Meristem Activity, Leaf Initiation, and Growth1[CC-BY

Science.gov (United States)

Mohammed, Binish; Bilooei, Sara Farahi; Grove, Elliot; Railo, Saana; Palme, Klaus

2018-01-01

The development of leaf primordia is subject to light control of meristematic activity. Light regulates the expression of thousands of genes with roles in cell proliferation, organ development, and differentiation of photosynthetic cells. Previous work has highlighted roles for hormone homeostasis and the energy-dependent Target of Rapamycin (TOR) kinase in meristematic activity, yet a picture of how these two regulatory mechanisms depend on light perception and interact with each other has yet to emerge. Their relevance beyond leaf initiation also is unclear. Here, we report the discovery that the dark-arrested meristematic region of Arabidopsis (Arabidopsis thaliana) experiences a local energy deprivation state and confirm previous findings that the PIN1 auxin transporter is diffusely localized in the dark. Light triggers a rapid removal of the starvation state and the establishment of PIN1 polar membrane localization consistent with auxin export, both preceding the induction of cell cycle- and cytoplasmic growth-associated genes. We demonstrate that shoot meristematic activity can occur in the dark through the manipulation of auxin and cytokinin activity as well as through the activation of energy signaling, both targets of photomorphogenesis action, but the organ developmental outcomes differ: while TOR-dependent energy signals alone stimulate cell proliferation, the development of a normal leaf lamina requires photomorphogenesis-like hormonal responses. We further show that energy signaling adjusts the extent of cell cycle activity and growth of young leaves non-cellautonomously to available photosynthates and leads to organs constituted of a greater number of cells developing under higher irradiance. This makes energy signaling perhaps the most important biomass growth determinant under natural, unstressed conditions. PMID:29284741

Non-destructive measurement of soybean leaf thickness via X-ray computed tomography allows the study of diel leaf growth rhythms in the third dimension.

Science.gov (United States)

Pfeifer, Johannes; Mielewczik, Michael; Friedli, Michael; Kirchgessner, Norbert; Walter, Achim

2018-01-01

Present-day high-resolution leaf growth measurements provide exciting insights into diel (24-h) leaf growth rhythms and their control by the circadian clock, which match photosynthesis with oscillating environmental conditions. However, these methods are based on measurements of leaf area or elongation and neglect diel changes of leaf thickness. In contrast, the influence of various environmental stress factors to which leaves are exposed to during growth on the final leaf thickness has been studied extensively. Yet, these studies cannot elucidate how variation in leaf area and thickness are simultaneously regulated and influenced on smaller time scales. Only few methods are available to measure the thickness of young, growing leaves non-destructively. Therefore, we evaluated X-ray computed tomography to simultaneously and non-invasively record diel changes and growth of leaf thickness and area. Using conventional imaging and X-ray computed tomography leaf area, thickness and volume growth of young soybean leaves were simultaneously and non-destructively monitored at three cardinal time points during night and day for a period of 80 h under non-stressful growth conditions. Reference thickness measurements on paperboards were in good agreement to CT measurements. Comparison of CT with leaf mass data further proved the consistency of our method. Exploratory analysis showed that measurements were accurate enough for recording and analyzing relative diel changes of leaf thickness, which were considerably different to those of leaf area. Relative growth rates of leaf area were consistently positive and highest during 'nights', while diel changes in thickness fluctuated more and were temporarily negative, particularly during 'evenings'. The method is suitable for non-invasive, accurate monitoring of diel variation in leaf volume. Moreover, our results indicate that diel rhythms of leaf area and thickness show some similarity but are not tightly coupled. These

What Is a Leaf? An Online Tutorial and Tests

Science.gov (United States)

Burrows, Geoffrey

2008-01-01

A leaf is a fundamental unit in botany and understanding what constitutes a leaf is fundamental to many plant science activities. My observations and subsequent testing indicated that many students could not confidently and consistently recognise a leaf from a leaflet, or recognise basic leaf arrangements and the various types of compound or…

A rice kinase-protein interaction map.

Science.gov (United States)

Ding, Xiaodong; Richter, Todd; Chen, Mei; Fujii, Hiroaki; Seo, Young Su; Xie, Mingtang; Zheng, Xianwu; Kanrar, Siddhartha; Stevenson, Rebecca A; Dardick, Christopher; Li, Ying; Jiang, Hao; Zhang, Yan; Yu, Fahong; Bartley, Laura E; Chern, Mawsheng; Bart, Rebecca; Chen, Xiuhua; Zhu, Lihuang; Farmerie, William G; Gribskov, Michael; Zhu, Jian-Kang; Fromm, Michael E; Ronald, Pamela C; Song, Wen-Yuan

2009-03-01

Plants uniquely contain large numbers of protein kinases, and for the vast majority of the 1,429 kinases predicted in the rice (Oryza sativa) genome, little is known of their functions. Genetic approaches often fail to produce observable phenotypes; thus, new strategies are needed to delineate kinase function. We previously developed a cost-effective high-throughput yeast two-hybrid system. Using this system, we have generated a protein interaction map of 116 representative rice kinases and 254 of their interacting proteins. Overall, the resulting interaction map supports a large number of known or predicted kinase-protein interactions from both plants and animals and reveals many new functional insights. Notably, we found a potential widespread role for E3 ubiquitin ligases in pathogen defense signaling mediated by receptor-like kinases, particularly by the kinases that may have evolved from recently expanded kinase subfamilies in rice. We anticipate that the data provided here will serve as a foundation for targeted functional studies in rice and other plants. The application of yeast two-hybrid and TAPtag analyses for large-scale plant protein interaction studies is also discussed.

Modeling the leaf angle dynamics in rice plant.

Directory of Open Access Journals (Sweden)

Yonghui Zhang

Full Text Available The leaf angle between stem and sheath (SSA is an important rice morphological trait. The objective of this study was to develop and validate a dynamic SSA model under different nitrogen (N rates for selected rice cultivars. The time-course data of SSA were collected in three years, and a dynamic SSA model was developed for different main stem leaf ranks under different N rates for two selected rice cultivars. SSA increased with tiller age. The SSA of the same leaf rank increased with increase in N rate. The maximum SSA increased with leaf rank from the first to the third leaf, then decreased from the third to the final leaf. The relationship between the maximum SSA and leaf rank on main stem could be described with a linear piecewise function. The change of SSA with thermal time (TT was described by a logistic equation. A variety parameter (the maximum SSA of the 3rd leaf on main stem and a nitrogen factor were introduced to quantify the effect of cultivar and N rate on SSA. The model was validated against data collected from both pot and field experiments. The relative root mean square error (RRMSE was 11.56% and 14.05%, respectively. The resulting models could be used for virtual rice plant modeling and plant-type design.

Screening Study of Leaf Terpene Concentration of 75 Borneo Rainforest Plant Species: Relationships with Leaf Elemental Concentrations and Morphology

Directory of Open Access Journals (Sweden)

Jordi Sardans

2015-01-01

Full Text Available Terpenes confer advantage in plant protection against abiotic stresses such as heat and drought and biotic stresses such as herbivore and pathogen attack. We conducted a screening of leaf mono- and sesquiterpene concentrations in 75 common woody plant species in the rainforest of Danum Valley (Borneo. Terpene compounds were found in 73 out of the 75 analysed species. Similar or lower proportions have been reported in other parts of the world. To our knowledge, this study reports for the first time the foliar concentration of mono- and/or sesquiterpene for 71 species and 39 genera not previously analyzed. Altogether 80 terpene compounds were determined across the species, and out of these only linalool oxide and (E- g -bisabolene had phylogenetic signal. A significant negative relationship between leaf monoterpene concentration and leaf length was observed, but leaf mono- and sesquitepene concentration were not related to any other leaf morphological trait nor to leaf elemental composition. Functions such as temperature protection, radiation protection or signaling and communication could underlie the high frequency of terpene-containing species of this tropical ecosystem which has multiple and very diverse interactions among multiple species.

Measurement of Leaf Mass and Leaf Area of Oaks In A Mediterranean-climate Region For Biogenic Emission Estimation

Science.gov (United States)

Karlik, J.

Given the key role played by biogenic volatile organic compounds (BVOC) in tro- pospheric chemistry and regional air quality, it is critical to generate accurate BVOC emission inventories. Because several oak species have high BVOC emission rates, and oak trees are often of large stature with corresponding large leaf masses, oaks may be the most important genus of woody plants for BVOC emissions modeling in the natural landscapes of Mediterranean-climate regions. In California, BVOC emis- sions from oaks may mix with anthropogenic emissions from urban areas, leading to elevated levels of ozone. Data for leaf mass and leaf area for a stand of native blue oaks (Quercus douglasii) were obtained through harvest and leaf removal from 14 trees lo- cated in the Sierra Nevada foothills of central California. Trees ranged in height from 4.2 to 9.9 m, with trunk diameters at breast height of 14 to 85 cm. Mean leaf mass density was 730 g m-2 for the trees and had an overall value of 310 g m-2 for the site. Consideration of the surrounding grassland devoid of trees resulted in a value of about 150 g m-2, less than half of reported values for eastern U.S. oak woodlands, but close to a reported value for oaks found in St. Quercio, Italy. The mean value for leaf area index (LAI) for the trees at this site was 4.4 m2 m-2. LAI for the site was 1.8 m2 m-2, but this value was appropriate for the oak grove only; including the surrounding open grassland resulted in an overall LAI value of 0.9 m2 m-2 or less. A volumetric method worked well for estimating the leaf mass of the oak trees. Among allometric relationships investigated, trunk circumference, mean crown radius, and crown projec- tion were well correlated with leaf mass. Estimated emission of isoprene (mg C m-2 h-1) for the site based these leaf mass data and experimentally determined emission rate was similar to that reported for a Mediterranean oak woodland in France.

Chitin and stress induced protein kinase activation

DEFF Research Database (Denmark)

Kenchappa, Chandra Shekar; Azevedo da Silva, Raquel; Bressendorff, Simon

2017-01-01

The assays described here are pertinent to protein kinase studies in any plant. They include an immunoblot phosphorylation/activation assay and an in-gel activity assay for MAP kinases (MPKs) using the general protein kinase substrate myelin basic protein. They also include a novel in-gel peptide...... substrate assay for Snf1-related kinase family 2 members (SnRK2s). This kinase family-specific assay overcomes some limitations of in-gel assays and permits the identification of different types of kinase activities in total protein extracts....

The Fast-Growing Brucella suis Biovar 5 Depends on Phosphoenolpyruvate Carboxykinase and Pyruvate Phosphate Dikinase but Not on Fbp and GlpX Fructose-1,6-Bisphosphatases or Isocitrate Lyase for Full Virulence in Laboratory Models

Directory of Open Access Journals (Sweden)

Amaia Zúñiga-Ripa

2018-04-01

Full Text Available Bacteria of the genus Brucella infect a range of vertebrates causing a worldwide extended zoonosis. The best-characterized brucellae infect domestic livestock, behaving as stealthy facultative intracellular parasites. This stealthiness depends on envelope molecules with reduced pathogen-associated molecular patterns, as revealed by the low lethality and ability to persist in mice of these bacteria. Infected cells are often engorged with brucellae without signs of distress, suggesting that stealthiness could also reflect an adaptation of the parasite metabolism to use local nutrients without harming the cell. To investigate this, we compared key metabolic abilities of Brucella abortus 2308 Wisconsin (2308W, a cattle biovar 1 virulent strain, and B. suis 513, the reference strain of the ancestral biovar 5 found in wild rodents. B. suis 513 used a larger number of C substrates and showed faster growth rates in vitro, two features similar to those of B. microti, a species phylogenomically close to B. suis biovar 5 that infects voles. However, whereas B. microti shows enhanced lethality and reduced persistence in mice, B. suis 513 was similar to B. abortus 2308W in this regard. Mutant analyses showed that B. suis 513 and B. abortus 2308W were similar in that both depend on phosphoenolpyruvate synthesis for virulence but not on the classical gluconeogenic fructose-1,6-bisphosphatases Fbp-GlpX or on isocitrate lyase (AceA. However, B. suis 513 used pyruvate phosphate dikinase (PpdK and phosphoenolpyruvate carboxykinase (PckA for phosphoenolpyruvate synthesis in vitro while B. abortus 2308W used only PpdK. Moreover, whereas PpdK dysfunction causes attenuation of B. abortus 2308W in mice, in B. suis, 513 attenuation occurred only in the double PckA-PpdK mutant. Also contrary to what occurs in B. abortus 2308, a B. suis 513 malic enzyme (Mae mutant was not attenuated, and this independence of Mae and the role of PpdK was confirmed by the lack of

Engineering of kinase-based protein interacting devices: active expression of tyrosine kinase domains

KAUST Repository

Diaz Galicia, Miriam Escarlet

2018-01-01

is then translated into a FRET (Fluorescence Resonance Energy Transfer) signal is here proposed. To this end, DNA constructs for interaction amplification (split kinases), positive controls (intact kinase domains), scaffolding proteins and phosphopeptide - SH2-domain

Receptor Tyrosine Kinases in Drosophila Development

Science.gov (United States)

Sopko, Richelle; Perrimon, Norbert

2013-01-01

Tyrosine phosphorylation plays a significant role in a wide range of cellular processes. The Drosophila genome encodes more than 20 receptor tyrosine kinases and extensive studies in the past 20 years have illustrated their diverse roles and complex signaling mechanisms. Although some receptor tyrosine kinases have highly specific functions, others strikingly are used in rather ubiquitous manners. Receptor tyrosine kinases regulate a broad expanse of processes, ranging from cell survival and proliferation to differentiation and patterning. Remarkably, different receptor tyrosine kinases share many of the same effectors and their hierarchical organization is retained in disparate biological contexts. In this comprehensive review, we summarize what is known regarding each receptor tyrosine kinase during Drosophila development. Astonishingly, very little is known for approximately half of all Drosophila receptor tyrosine kinases. PMID:23732470

Leaf-jams - A new and unique leaf deposit in the ephemeral Hoanib River, NW Namibia: Origin and plant taphonomic implications

Energy Technology Data Exchange (ETDEWEB)

Hofmann, Christa-Ch. [University of Vienna, Department of Palaeontology, Palaeobotany Studies Group, Althanstrasse 14, 1090, Vienna (Austria); Rice, A. Hugh N. [University of Vienna, Department of Geodynamics and Sedimentology, Althanstrasse 14, 1090, Vienna (Austria)

2010-08-01

This paper documents a previously unrecorded type of leaf deposit, comprising essentially monospecific linear accumulations of Colophospermum mopane leaves on a point bar of the ephemeral Hoanib River, NW Namibia. In these 'leaf-jams', leaf laminae stand on edge, orientated more-or-less normal to bedding. Leaf-jams, which formed upstream of cobbles, clumps of grass and sticks wedged against the former two, were orientated subparallel to the adjacent meandering river-bed, such that over the 40 m of their occurrence, their mean azimuth changed by 59 anticlockwise downstream. The longest leaf-jam was 50 cm and contained approximately 500 leaves, as well as grass culms, twigs (C. mopane, Tamarix usneoides and unidentified) and medium- to fine-grained sand and silt. Individual leaf-jams were partially buried in the point bar sediments up to a depth of 3 cm. Leaf-jam formation occurred in the austral summer of 2006, during the waning stage of a major flood caused by anomalous tropical to extra-tropical storms. Their monospecifity is due to the overwhelming preponderance of the zonal taxon C. mopane in the catchment area, although the Khowarib Gorge contains a quite diverse azonal plant association due to the presence of a permanent water-seep. During leaf-jam formation, the water depth was less than the height of the cobbles (0.1 m), with stream flow-rates competent to transport medium-grained sand (velocity estimated at 0.5 m s{sup -} {sup 1}). Leaves must have been partially or fully waterlogged to inhibit buoyancy forces tending to lift them out of the developing leaf-jams, which propagated upstream in a manner comparable to longitudinal bars in a braided river. If fossilised, such deposits would probably lead to a very biased interpretation of the composition of the surrounding flora; the correct interpretation would be the one least favoured by palaeobotanists. (author)

Prebiotic Fiber Increases Hepatic Acetyl CoA Carboxylase Phosphorylation and Suppresses Glucose-Dependent Insulinotropic Polypeptide Secretion More Effectively When Used with Metformin in Obese Rats1,2

Science.gov (United States)

Pyra, Kim A.; Saha, Dolan C.; Reimer, Raylene A.

2013-01-01

Independently, metformin (MET) and the prebiotic, oligofructose (OFS), have been shown to increase glucagon-like peptide (GLP-1) secretion. Our objective was to determine whether using OFS as an adjunct with MET augments GLP-1 secretion in obese rats. Male, diet-induced obese Sprague Dawley rats were randomized to: 1) high-fat/-sucrose diet [HFHS; control (C); 20% fat, 50% sucrose wt:wt]; 2) HFHS+10% OFS (OFS); 3) HFHS + MET [300 mg/kg/d (MET)]; 4) HFHS+10% OFS+MET (OFS +MET). Body composition, glycemia, satiety hormones, and mechanisms related to dipeptidyl peptidase 4 (DPP4) activity in plasma, hepatic AMP-activated protein kinase (AMPK; Western blots), and gut microbiota (qPCR) were examined. Direct effects of MET and SCFA were examined in human enteroendocrine cells. The interaction between OFS and MET affected fat mass, hepatic TG, secretion of glucose-dependent insulinotropic polypeptide (GIP) and leptin, and AMPKα2 mRNA and phosphorylated acetyl CoA carboxylase (pACC) levels (P < 0.05). Combined, OFS and MET reduced GIP secretion to a greater extent than either treatment alone (P < 0.05). The hepatic pACC level was increased by OFS+MET by at least 50% above all other treatments, which did not differ from each other (P < 0.05). OFS decreased plasma DPP4 activity (P < 0.001). Cecal Bifidobacteria (P < 0.001) were markedly increased and C. leptum decreased (P < 0.001) with OFS consumption. In human enteroendocrine cells, the interaction between MET and SCFA affected GLP-1 secretion (P < 0.04) but was not associated with higher GLP-1 than the highest individual doses. In conclusion, the combined actions of OFS and MET were associated with important interaction effects that have the potential to improve metabolic outcomes associated with obesity. PMID:22223580

Chromosome-damaging effect of betel leaf.

Science.gov (United States)

Sadasivan, G; Rani, G; Kumari, C K

1978-05-01

The chewing of betel leaf with other ingredients is a widespread addiction in India. The chromosome damaging effect was studied in human leukocyte cultures. There was an increase in the frequency of chromatid aberrations when the leaf extract was added to cultures.

Staphylococcal phosphoenolpyruvate-dependent phosphotransferase system: purification and characterization of the mannitol-specific enzyme III/sup mtl/ of Staphylococcus aureus and Staphylococcus carnosus and homology with the enzyme II/sup mtl/ of Escherichia coli

International Nuclear Information System (INIS)

Reiche, B.; Frank, R.; Deutscher, J.; Meyer, N.; Hengstenberg, W.

1988-01-01

Enzyme III/sup mtl/ is part of the mannitol phosphotransferase system of Staphylococcus aureus and Staphylococcus carnosus and is phosphorylated by phosphoenolpyruvate in a reaction sequence requiring enzyme I (phosphoenolpyruvate-protein phosphotransferase) and the histidine-containing protein HPr. In this paper, the authors report the isolation of III/sup mtl/ from both S. aureus and S. carnosus and the characterization of the active center. After phosphorylation of III/sup mtl/ with [ 32 P]PEP, enzyme I, and HPr, the phosphorylated protein was cleaved with endoproteinase GLu(C). The amino acid sequence of the S. aureus peptide carrying the phosphoryl group was found to be Gln-Val-Val-Ser-Thr-Phe-Met-Gly-Asn-Gly-Leu-Ala-Ile-Pro-His-Gly-Thr-Asp-Asp. The corresponding peptide from S. carnosus shows an equal sequence except that the first residue is Ala instead of Gln. These peptides both contain a single histidyl residue which they assume to carry the phosphoryl group. All proteins of the PTS so far investigated indeed carry the phosphoryl group attached to a histidyl residue. According to sodium dodecyl sulfate gels, the molecular weight of the III/sup mtl/ proteins was found to be 15,000. They have also determined the N-terminal sequence of both proteins. Comparison of the III/sup mtl/ peptide sequences and the C-terminal part of the enzyme II/sup mtl/ of Escherichia coli reveals considerable sequence homology, which supports the suggestion that II/sup mtl/ of E. coli is a fusion protein of a soluble III protein with a membrane-bound enzyme II

A cGMP kinase mutant with increased sensitivity to the protein kinase inhibitor peptide PKI(5-24).

Science.gov (United States)

Ruth, P; Kamm, S; Nau, U; Pfeifer, A; Hofmann, F

1996-01-01

Synthetic peptides corresponding to the active domain of the heat-stable inhibitor protein PKI are very potent inhibitors of cAMP-dependent protein kinase, but are extremely weak inhibitors of cGMP-dependent protein kinase. In this study, we tried to confer PKI sensitivity to cGMP kinase by site-directed mutagenesis. The molecular requirements for high affinity inhibition by PKI were deduced from the crystal structure of the cAMP kinase/PKI complex. A prominent site of interaction are residues Tyr235 and Phe239 in the catalytic subunit, which from a sandwich-like structure with Phe10 of the PKI(5-24) peptide. To increase the sensitivity for PKI, the cGMP kinase codons at the corresponding sites, Ser555 and Ser559, were changed to Tyr and Phe. The mutant cGMP kinase was stimulated half maximally by cGMP at 3-fold higher concentrations (240 nM) than the wild type (77 nM). Wild type and mutant cGMP kinase did not differ significantly in their Km and Vmax for three different substrate peptides. The PKI(5-24) peptide inhibited phosphotransferase activity of the mutant cGMP kinase with higher potency than that of wild type, with Ki values of 42 +/- .3 microM and 160 +/- .7 microM, respectively. The increased affinity of the mutant cGMP kinase was specific for the PKI(5-24) peptide. Mutation of the essential Phe10 in the PKI(5-24) sequence to an Ala yielded a peptide that inhibited mutant and wild type cGMP kinase with similar potency, with Ki values of 160 +/- 11 and 169 +/- 27 microM, respectively. These results suggest that the mutations Ser555Tyr and Ser559Phe are required, but not sufficient, for high affinity inhibition of cGMP kinase by PKI.

ROS and CDPK-like kinase-mediated activation of MAP kinase in rice roots exposed to lead.

Science.gov (United States)

Huang, Tsai-Lien; Huang, Hao-Jen

2008-04-01

Lead (Pb2+) is a cytotoxic metal ion in plants, the mechanism of which is not yet established. The aim of this study is to investigate the signalling pathways that are activated by elevated concentrations of Pb2+ in rice roots. Root growth was stunted and cell death was accelerated when exposed to different dosages of Pb2+ during extended time periods. Using ROS-sensitive dye and Ca2+ indicator, we demonstrated that Pb2+ induced ROS production and Ca2+ accumulation, respectively. In addition, Pb2+ elicited a remarkable increase in myelin basic protein (MBP) kinase activities. By immunoblot and immunoprecipitation analysis, 40- and 42-kDa MBP kinases that were activated by Pb2+ were identified to be mitogen-activated protein (MAP) kinases. Pre-treatment of rice roots with an antioxidant and a NADPH oxidase inhibitor, glutathione (GSH) and diphenylene iodonium (DPI), effectively reduced Pb2+-induced cell death and MAP kinase activation. Moreover, calcium-dependent protein kinase (CDPK) antagonist, W7, attenuated Pb2+-induced cell death and MAP kinase activation. These results suggested that the ROS and CDPK may function in the Pb2+-triggered cell death and MAP kinase signalling pathway in rice roots.

Does leaf chemistry differentially affect breakdown in tropical vs temperate streams? Importance of standardized analytical techniques to measure leaf chemistry

Science.gov (United States)

Marcelo Ard& #243; n; Catherine M. Pringle; Susan L. Eggert

2009-01-01

Comparisons of the effects of leaf litter chemistry on leaf breakdown rates in tropical vs temperate streams are hindered by incompatibility among studies and across sites of analytical methods used to measure leaf chemistry. We used standardized analytical techniques to measure chemistry and breakdown rate of leaves from common riparian tree species at 2 sites, 1...

7 CFR 29.2277 - Leaf scrap.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists...

Impact of anatomical traits of maize (Zea mays L.) leaf as affected by nitrogen supply and leaf age on bundle sheath conductance.

Science.gov (United States)

Retta, Moges; Yin, Xinyou; van der Putten, Peter E L; Cantre, Denis; Berghuijs, Herman N C; Ho, Quang Tri; Verboven, Pieter; Struik, Paul C; Nicolaï, Bart M

2016-11-01

The mechanism of photosynthesis in C 4 crops depends on the archetypal Kranz-anatomy. To examine how the leaf anatomy, as altered by nitrogen supply and leaf age, affects the bundle sheath conductance (g bs ), maize (Zea mays L.) plants were grown under three contrasting nitrogen levels. Combined gas exchange and chlorophyll fluorescence measurements were done on fully grown leaves at two leaf ages. The measured data were analysed using a biochemical model of C 4 photosynthesis to estimate g bs . The leaf microstructure and ultrastructure were quantified using images obtained from micro-computed tomography and microscopy. There was a strong positive correlation between g bs and leaf nitrogen content (LNC) while old leaves had lower g bs than young leaves. Leaf thickness, bundle sheath cell wall thickness and surface area of bundle sheath cells per unit leaf area (S b ) correlated well with g bs although they were not significantly affected by LNC. As a result, the increase of g bs with LNC was little explained by the alteration of leaf anatomy. In contrast, the combined effect of LNC and leaf age on S b was responsible for differences in g bs between young leaves and old leaves. Future investigations should consider changes at the level of plasmodesmata and membranes along the CO 2 leakage pathway to unravel LNC and age effects further. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Characterization of C₃--C₄ intermediate species in the genus Heliotropium L. (Boraginaceae): anatomy, ultrastructure and enzyme activity.

Science.gov (United States)

Muhaidat, Riyadh; Sage, Tammy L; Frohlich, Michael W; Dengler, Nancy G; Sage, Rowan F

2011-10-01

Photosynthetic pathway characteristics were studied in nine species of Heliotropium (sensu lato, including Euploca), using assessments of leaf anatomy and ultrastructure, activities of PEP carboxylase and C₄ acid decarboxylases, and immunolocalization of ribulose 1·5-bisphosphate carboxylase/oxygenase (Rubisco) and the P-subunit of glycine decarboxylase (GDC). Heliotropium europaeum, Heliotropium calcicola and Heliotropium tenellum are C₃ plants, while Heliotropium texanum and Heliotropium polyphyllum are C₄ species. Heliotropium procumbens and Heliotropium karwinskyi are functionally C₃, but exhibit 'proto-Kranz' anatomy where bundle sheath (BS) cells are enlarged and mitochondria primarily occur along the centripetal (inner) wall of the BS cells; GDC is present throughout the leaf. Heliotropium convolvulaceum and Heliotropium greggii are C₃--C₄ intermediates, with Kranz-like enlargement of the BS cells, localization of mitochondria along the inner BS wall and a loss of GDC in the mesophyll (M) tissue. These C₃--C₄ species of Heliotropium probably shuttle photorespiratory glycine from the M to the BS tissue for decarboxylation. Heliotropium represents an important new model for studying C₄ evolution. Where existing models such as Flaveria emphasize diversification of C₃--C₄ intermediates, Heliotropium has numerous C₃ species expressing proto-Kranz traits that could represent a critical initial phase in the evolutionary origin of C₄ photosynthesis. © 2011 Blackwell Publishing Ltd.

Photoperiod-H1 (Ppd-H1) Controls Leaf Size1[OPEN

Science.gov (United States)

Digel, Benedikt; Tavakol, Elahe; Verderio, Gabriele; Xu, Xin

2016-01-01

Leaf size is a major determinant of plant photosynthetic activity and biomass; however, it is poorly understood how leaf size is genetically controlled in cereal crop plants like barley (Hordeum vulgare). We conducted a genome-wide association scan for flowering time, leaf width, and leaf length in a diverse panel of European winter cultivars grown in the field and genotyped with a single-nucleotide polymorphism array. The genome-wide association scan identified PHOTOPERIOD-H1 (Ppd-H1) as a candidate gene underlying the major quantitative trait loci for flowering time and leaf size in the barley population. Microscopic phenotyping of three independent introgression lines confirmed the effect of Ppd-H1 on leaf size. Differences in the duration of leaf growth and consequent variation in leaf cell number were responsible for the leaf size differences between the Ppd-H1 variants. The Ppd-H1-dependent induction of the BARLEY MADS BOX genes BM3 and BM8 in the leaf correlated with reductions in leaf size and leaf number. Our results indicate that leaf size is controlled by the Ppd-H1- and photoperiod-dependent progression of plant development. The coordination of leaf growth with flowering may be part of a reproductive strategy to optimize resource allocation to the developing inflorescences and seeds. PMID:27457126

Leaf wetness distribution within a potato crop

Science.gov (United States)

Heusinkveld, B. G.

2010-07-01

The Netherlands has a mild maritime climate and therefore the major interest in leaf wetness is associated with foliar plant diseases. During moist micrometeorological conditions (i.e. dew, fog, rain), foliar fungal diseases may develop quickly and thereby destroy a crop quickly. Potato crop monocultures covering several hectares are especially vulnerable to such diseases. Therefore understanding and predicting leaf wetness in potato crops is crucial in crop disease control strategies. A field experiment was carried out in a large homogeneous potato crop in the Netherlands during the growing season of 2008. Two innovative sensor networks were installed as a 3 by 3 grid at 3 heights covering an area of about 2 hectares within two larger potato crops. One crop was located on a sandy soil and one crop on a sandy peat soil. In most cases leaf wetting starts in the top layer and then progresses downward. Leaf drying takes place in the same order after sunrise. A canopy dew simulation model was applied to simulate spatial leaf wetness distribution. The dew model is based on an energy balance model. The model can be run using information on the above-canopy wind speed, air temperature, humidity, net radiation and within canopy air temperature, humidity and soil moisture content and temperature conditions. Rainfall was accounted for by applying an interception model. The results of the dew model agreed well with the leaf wetness sensors if all local conditions were considered. The measurements show that the spatial correlation of leaf wetness decreases downward.

A screen for kinase inhibitors identifies antimicrobial imidazopyridine aminofurazans as specific inhibitors of the Listeria monocytogenes PASTA kinase PrkA.

Science.gov (United States)

Schaenzer, Adam J; Wlodarchak, Nathan; Drewry, David H; Zuercher, William J; Rose, Warren E; Striker, Rob; Sauer, John-Demian

2017-10-13

Bacterial signaling systems such as protein kinases and quorum sensing have become increasingly attractive targets for the development of novel antimicrobial agents in a time of rising antibiotic resistance. The family of bacterial P enicillin-binding-protein A nd S erine/ T hreonine kinase- A ssociated (PASTA) kinases is of particular interest due to the role of these kinases in regulating resistance to β-lactam antibiotics. As such, small-molecule kinase inhibitors that target PASTA kinases may prove beneficial as treatments adjunctive to β-lactam therapy. Despite this interest, only limited progress has been made in identifying functional inhibitors of the PASTA kinases that have both activity against the intact microbe and high kinase specificity. Here, we report the results of a small-molecule screen that identified GSK690693, an imidazopyridine aminofurazan-type kinase inhibitor that increases the sensitivity of the intracellular pathogen Listeria monocytogenes to various β-lactams by inhibiting the PASTA kinase PrkA. GSK690693 potently inhibited PrkA kinase activity biochemically and exhibited significant selectivity for PrkA relative to the Staphylococcus aureus PASTA kinase Stk1. Furthermore, other imidazopyridine aminofurazans could effectively inhibit PrkA and potentiate β-lactam antibiotic activity to varying degrees. The presence of the 2-methyl-3-butyn-2-ol (alkynol) moiety was important for both biochemical and antimicrobial activity. Finally, mutagenesis studies demonstrated residues in the back pocket of the active site are important for GSK690693 selectivity. These data suggest that targeted screens can successfully identify PASTA kinase inhibitors with both biochemical and antimicrobial specificity. Moreover, the imidazopyridine aminofurazans represent a family of PASTA kinase inhibitors that have the potential to be optimized for selective PASTA kinase inhibition.

CIKS, a connection to Ikappa B kinase and stress-activated protein kinase.

Science.gov (United States)

Leonardi, A; Chariot, A; Claudio, E; Cunningham, K; Siebenlist, U

2000-09-12

Pathogens, inflammatory signals, and stress cause acute transcriptional responses in cells. The induced expression of genes in response to these signals invariably involves transcription factors of the NF-kappaB and AP-1/ATF families. Activation of NF-kappaB factors is thought to be mediated primarily via IkappaB kinases (IKK), whereas that of AP-1/ATF can be mediated by stress-activated protein kinases (SAPKs; also named Jun kinases or JNKs). IKKalpha and IKKbeta are two catalytic subunits of a core IKK complex that also contains the regulatory subunit NEMO (NF-kappaB essential modulator)/IKKgamma. The latter protein is essential for activation of the IKKs, but its mechanism of action is not known. Here we describe the molecular cloning of CIKS (connection to IKK and SAPK/JNK), a previously unknown protein that directly interacts with NEMO/IKKgamma in cells. When ectopically expressed, CIKS stimulates IKK and SAPK/JNK kinases and it transactivates an NF-kappaB-dependent reporter. Activation of NF-kappaB is prevented in the presence of kinase-deficient, interfering mutants of the IKKs. CIKS may help to connect upstream signaling events to IKK and SAPK/JNK modules. CIKS could coordinate the activation of two stress-induced signaling pathways, functions reminiscent of those noted for tumor necrosis factor receptor-associated factor adaptor proteins.

CIKS, a connection to IκB kinase and stress-activated protein kinase

Science.gov (United States)

Leonardi, Antonio; Chariot, Alain; Claudio, Estefania; Cunningham, Kirk; Siebenlist, Ulrich

2000-01-01

Pathogens, inflammatory signals, and stress cause acute transcriptional responses in cells. The induced expression of genes in response to these signals invariably involves transcription factors of the NF-κB and AP-1/ATF families. Activation of NF-κB factors is thought to be mediated primarily via IκB kinases (IKK), whereas that of AP-1/ATF can be mediated by stress-activated protein kinases (SAPKs; also named Jun kinases or JNKs). IKKα and IKKβ are two catalytic subunits of a core IKK complex that also contains the regulatory subunit NEMO (NF-κB essential modulator)/IKKγ. The latter protein is essential for activation of the IKKs, but its mechanism of action is not known. Here we describe the molecular cloning of CIKS (connection to IKK and SAPK/JNK), a previously unknown protein that directly interacts with NEMO/IKKγ in cells. When ectopically expressed, CIKS stimulates IKK and SAPK/JNK kinases and it transactivates an NF-κB-dependent reporter. Activation of NF-κB is prevented in the presence of kinase-deficient, interfering mutants of the IKKs. CIKS may help to connect upstream signaling events to IKK and SAPK/JNK modules. CIKS could coordinate the activation of two stress-induced signaling pathways, functions reminiscent of those noted for tumor necrosis factor receptor-associated factor adaptor proteins. PMID:10962033

Foraging on individual leaves by an intracellular feeding insect is not associated with leaf biomechanical properties or leaf orientation.

Directory of Open Access Journals (Sweden)

Justin Fiene

Full Text Available Nearly all herbivorous arthropods make foraging-decisions on individual leaves, yet systematic investigations of the adaptive significance and ecological factors structuring these decisions are rare with most attention given to chewing herbivores. This study investigated why an intracellular feeding herbivore, Western flower thrips (WFT Frankliniella occidentalis Pergande, generally avoids feeding on the adaxial leaf surface of cotton cotyledons. WFT showed a significant aversion to adaxial-feeding even when excised-cotyledons were turned up-side (abaxial-side 'up', suggesting that negative-phototaxis was not a primary cause of thrips foraging patterns. No-choice bioassays in which individual WFT females were confined to either the abaxial or adaxial leaf surface showed that 35% fewer offspring were produced when only adaxial feeding was allowed, which coincided with 32% less plant feeding on that surface. To test the hypothesis that leaf biomechanical properties inhibited thrips feeding on the adaxial surface, we used a penetrometer to measure two variables related to the 'toughness' of each leaf surface. Neither variable negatively co-varied with feeding. Thus, while avoiding the upper leaf surface was an adaptive foraging strategy, the proximate cause remains to be elucidated, but is likely due, in part, to certain leaf properties that inhibit feeding.

Influence of the nitrate concentration and source in the incorporation of 14CO2 by the RuBP-carboxylase from wheat (triticum aestivum) and maize (zea mays)

International Nuclear Information System (INIS)

Saez Angulo, R.M.; Gines Diaz, M.J.; Garcia Pineda, M.D.

1982-01-01

The effect of the concentration and source of nitrogen in the culture media has been studied regarding its influence in the activity of the RuBP-carboxylase from wheat and maize during the first month of development. Wheat and maize has been chosen as plants representatives of two different types of CO 2 assimilation: C3 and M- respectively. Plants have been grown in hydroponic media and under temperature, humidity and nutrient salts control. A negative effect of NH 4 has been observed in the enzymatic activity of wheat seedlings, being this effect more remarkable as NH 4 concentration increases and as long the time of treatment. In our experimental conditions the most favorable source of nitrogen has been N0 3 NH 4 . The specific activity of the enzyme from wheat is about four times higher than in maize, even it decreases with time. This decreasing has not been observed in maize, with the exception of total absence of nitrogen in the media. We have not seen significant differences between the two photo periods which have been tested. Also, no differences have been found in the enzyme activities at the different NO 3 NH 4 concentrations assayed, and it seems that RuBP-carboxylase metabolism is only affected in the case of absolute stress. (Author) 20 refs

Kinases Involved in Both Autophagy and Mitosis.

Science.gov (United States)

Li, Zhiyuan; Zhang, Xin

2017-08-31

Both mitosis and autophagy are highly regulated dynamic cellular processes and involve various phosphorylation events catalysed by kinases, which play vital roles in almost all physiological and pathological conditions. Mitosis is a key event during the cell cycle, in which the cell divides into two daughter cells. Autophagy is a process in which the cell digests its own cellular contents. Although autophagy regulation has mainly been studied in asynchronous cells, increasing evidence indicates that autophagy is in fact tightly regulated in mitosis. Here in this review, we will discuss kinases that were originally identified to be involved in only one of either mitosis or autophagy, but were later found to participate in both processes, such as CDKs (cyclin-dependent kinases), Aurora kinases, PLK-1 (polo-like kinase 1), BUB1 (budding uninhibited by benzimidazoles 1), MAPKs (mitogen-activated protein kinases), mTORC1 (mechanistic target of rapamycin complex 1), AMPK (AMP-activated protein kinase), PI3K (phosphoinositide-3 kinase) and protein kinase B (AKT). By focusing on kinases involved in both autophagy and mitosis, we will get a more comprehensive understanding about the reciprocal regulation between the two key cellular events, which will also shed light on their related therapeutic investigations.

Kinases Involved in Both Autophagy and Mitosis

Directory of Open Access Journals (Sweden)

Zhiyuan Li

2017-08-01

Full Text Available Both mitosis and autophagy are highly regulated dynamic cellular processes and involve various phosphorylation events catalysed by kinases, which play vital roles in almost all physiological and pathological conditions. Mitosis is a key event during the cell cycle, in which the cell divides into two daughter cells. Autophagy is a process in which the cell digests its own cellular contents. Although autophagy regulation has mainly been studied in asynchronous cells, increasing evidence indicates that autophagy is in fact tightly regulated in mitosis. Here in this review, we will discuss kinases that were originally identified to be involved in only one of either mitosis or autophagy, but were later found to participate in both processes, such as CDKs (cyclin-dependent kinases, Aurora kinases, PLK-1 (polo-like kinase 1, BUB1 (budding uninhibited by benzimidazoles 1, MAPKs (mitogen-activated protein kinases, mTORC1 (mechanistic target of rapamycin complex 1, AMPK (AMP-activated protein kinase, PI3K (phosphoinositide-3 kinase and protein kinase B (AKT. By focusing on kinases involved in both autophagy and mitosis, we will get a more comprehensive understanding about the reciprocal regulation between the two key cellular events, which will also shed light on their related therapeutic investigations.

Partial purification and characterization of a wortmannin-sensitive and insulin-stimulated protein kinase that activates heart 6-phosphofructo-2-kinase.

OpenAIRE

Deprez, J; Bertrand, L; Alessi, D R; Krause, U; Hue, L; Rider, M H

2000-01-01

A wortmannin-sensitive and insulin-stimulated protein kinase (WISK), which phosphorylates and activates cardiac 6-phosphofructo-2-kinase (PFK-2), was partially purified from perfused rat hearts. Immunoblotting showed that WISK was devoid of protein kinase B (PKB), serum- and glucocorticoid-regulated protein kinase and protein kinase Czeta (PKCzeta). Comparison of the inhibition of WISK, PKCalpha and PKCzeta by different protein kinase inhibitors suggested that WISK was not a member of the PKC...

7 CFR 29.2278 - Leaf structure.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ...

7 CFR 29.2529 - Leaf scrap.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or...

Tangshen formula attenuates hepatic steatosis by inhibiting hepatic lipogenesis and augmenting fatty acid oxidation in db/db mice.

Science.gov (United States)

Kong, Qin; Zhang, Haojun; Zhao, Tingting; Zhang, Weiku; Yan, Meihua; Dong, Xi; Li, Ping

2016-12-01

Tangshen formula (TSF), a well-prescribed traditional Chinese formula, has been used in the treatment of diabetic nephropathy. However, whether TSF ameliorates dyslipidemia and liver injury associated with diabetes remains unclear. In this study, we examined the effects of TSF on lipid profiles and hepatic steatosis in db/db mice. For this purpose, 8‑week-old db/db mice were treated with TSF or saline for 12 weeks via gavage and db/m mice were used as controls. Body weight and blood glucose levels were monitored weekly and bi-weekly, respectively. Blood samples were obtained for the analysis of lipids and enzymes related to hepatic function, and liver tissues were analyzed by histology, immunohistochemistry and molecular examination. The results revealed that TSF markedly reduced body weight, liver index [liver/body weight (LW/BW)] and improved lipid profiles, hepatic function and steatosis in db/db mice. TSF induced the phosphoralation of AMP-activated protein kinase and inhibited the activity of sterol regulatory element-binding protein 1 together with the inhibition of the expression of genes involved in de novo lipogenesis (DNL) and gluconeogenesis, such as fatty acid synthase (FAS), acetyl-CoA carboxylase (ACC), stearoyl CoA desaturase 1 (SCD1), glucose-6-phosphatase (G6pc) and phosphoenolpyruvate carboxykinase 1 (Pck1). Additionally, the silent mating type information regulation 2 homolog 1 (Sirt1)/peroxisome proliferator-activated receptor α (PPARα)/malonyl-CoA decarboxylase (MLYCD) cascade was potently activated by TSF in the liver and skeletal muscle of db/db mice, which led to enhanced fatty acid oxidation. These findings demonstrated that TSF attenuated hepatic fat accumulation and steatosis in db/db mice by inhibiting lipogenesis and augmenting fatty acid oxidation.

O-GlcNAcylation mediates the control of cytosolic phosphoenolpyruvate carboxykinase activity via Pgc1α.

Directory of Open Access Journals (Sweden)

Pedro Latorre

Full Text Available PGC1α is a coactivator of many transcription factors and cytosolic phosphoenolpyruvate carboxykinase (PCK1 is a key enzyme for gluconeogenesis. PGC1α interacts with the transcription factor PPARγ to stimulate PCK1 expression and thus de novo glucose synthesis. These proteins are not only important for central energy metabolism but also for supplying intermediates for other metabolic pathways, including lipidogenesis and protein synthesis and might therefore be important factors in the ethiopathogenesis of metabolic disorders like diabetes but also in other pathologies like cancer. Since polymorphisms in these proteins have been related to some phenotypic traits in animals like pigs and PGC1α G482S polymorphism increases fat deposition in humans, we have investigated the molecular basis of such effects focusing on a commonly studied polymorphism in pig Pgc1α, which changes a cysteine at position 430 (WT of the protein to a serine (C430S. Biochemical analyses show that Pgc1α WT stimulates higher expression of human PCK1 in HEK293T and HepG2 cells. Paradoxically, Pgc1α WT is less stable than Pgc1α p.C430S in HEK293T cells. However, the study of different post-translational modifications shows a higher O-GlcNAcylation level of Pgc1α p.C430S. This higher O-GlcNAcylation level significantly decreases the interaction between Pgc1α and PPARγ demonstrating the importance of post-translational glycosylation of PGC1α in the regulation of PCK1 activity. This, furthermore, could explain at least in part the observed epistatic effects between PGC1α and PCK1 in pigs.

Inheritance of okra leaf type in different genetic backgrounds and its ...

African Journals Online (AJOL)

use

2011-11-21

Nov 21, 2011 ... discontinuous variation for leaf shape in F2 generations of three crosses .... Variable classes in leaf types (a) Normal leaf (b) Okra leaf (c) Sub-okra leaf. ..... insect pests on different isogenic lines of cotton variety H-777. J.

Adrenaline is a critical mediator of acute exercise-induced AMP-activated protein kinase activation in adipocytes

Science.gov (United States)

Koh, Ho-Jin; Hirshman, Michael F.; He, Huamei; Li, Yangfeng; Manabe, Yasuko; Balschi, James A.; Goodyear, Laurie J.

2007-01-01

Exercise increases AMPK (AMP-activated protein kinase) activity in human and rat adipocytes, but the underlying molecular mechanisms and functional consequences of this activation are not known. Since adrenaline (epinephrine) concentrations increase with exercise, in the present study we hypothesized that adrenaline activates AMPK in adipocytes. We show that a single bout of exercise increases AMPKα1 and α2 activities and ACC (acetyl-CoA carboxylase) Ser79 phosphorylation in rat adipocytes. Similarly to exercise, adrenaline treatment in vivo increased AMPK activities and ACC phosphorylation. Pre-treatment of rats with the β-blocker propranolol fully blocked exercise-induced AMPK activation. Increased AMPK activity with exercise and adrenaline treatment in vivo was accompanied by an increased AMP/ATP ratio. Adrenaline incubation of isolated adipocytes also increased the AMP/ATP ratio and AMPK activities, an effect blocked by propranolol. Adrenaline incubation increased lipolysis in isolated adipocytes, and Compound C, an AMPK inhibitor, attenuated this effect. Finally, a potential role for AMPK in the decreased adiposity associated with chronic exercise was suggested by marked increases in AMPKα1 and α2 activities in adipocytes from rats trained for 6 weeks. In conclusion, both acute and chronic exercise are significant regulators of AMPK activity in rat adipocytes. Our findings suggest that adrenaline plays a critical role in exercise-stimulated AMPKα1 and α2 activities in adipocytes, and that AMPK can function in the regulation of lipolysis. PMID:17253964

Signaling network of the Btk family kinases.

Science.gov (United States)

Qiu, Y; Kung, H J

2000-11-20

The Btk family kinases represent new members of non-receptor tyrosine kinases, which include Btk/Atk, Itk/Emt/Tsk, Bmx/Etk, and Tec. They are characterized by having four structural modules: PH (pleckstrin homology) domain, SH3 (Src homology 3) domain, SH2 (Src homology 2) domain and kinase (Src homology 1) domain. Increasing evidence suggests that, like Src-family kinases, Btk family kinases play central but diverse modulatory roles in various cellular processes. They participate in signal transduction in response to virtually all types of extracellular stimuli which are transmitted by growth factor receptors, cytokine receptors, G-protein coupled receptors, antigen-receptors and integrins. They are regulated by many non-receptor tyrosine kinases such as Src, Jak, Syk and FAK family kinases. In turn, they regulate many of major signaling pathways including those of PI3K, PLCgamma and PKC. Both genetic and biochemical approaches have been used to dissect the signaling pathways and elucidate their roles in growth, differentiation and apoptosis. An emerging new role of this family of kinases is cytoskeletal reorganization and cell motility. The physiological importance of these kinases was amply demonstrated by their link to the development of immunodeficiency diseases, due to germ-line mutations. The present article attempts to review the structure and functions of Btk family kinases by summarizing our current knowledge on the interacting partners associated with the different modules of the kinases and the diverse signaling pathways in which they are involved.

Waiting for the Leaf; Warten auf den Leaf

Energy Technology Data Exchange (ETDEWEB)

Wilms, Jan

2012-01-15

Nissan will be the first manufacturer to launch an electric vehicle of the VW Golf category in the German market. With a mileage of about 170 km and a roomy passenger compartment, the Leaf promises much comfort. In the US market, it was launched two years ago. Was it worth while waiting for?.

From leaf to whole-plant water use efficiency (WUE in complex canopies: Limitations of leaf WUE as a selection target

Directory of Open Access Journals (Sweden)

Hipólito Medrano

2015-06-01

Full Text Available Plant water use efficiency (WUE is becoming a key issue in semiarid areas, where crop production relies on the use of large volumes of water. Improving WUE is necessary for securing environmental sustainability of food production in these areas. Given that climate change predictions include increases in temperature and drought in semiarid regions, improving crop WUE is mandatory for global food production. WUE is commonly measured at the leaf level, because portable equipment for measuring leaf gas exchange rates facilitates the simultaneous measurement of photosynthesis and transpiration. However, when those measurements are compared with daily integrals or whole-plant estimates of WUE, the two sometimes do not agree. Scaling up from single-leaf to whole-plant WUE was tested in grapevines in different experiments by comparison of daily integrals of instantaneous water use efficiency [ratio between CO2 assimilation (AN and transpiration (E; AN/E] with midday AN/E measurements, showing a low correlation, being worse with increasing water stress. We sought to evaluate the importance of spatial and temporal variation in carbon and water balances at the leaf and plant levels. The leaf position (governing average light interception in the canopy showed a marked effect on instantaneous and daily integrals of leaf WUE. Night transpiration and respiration rates were also evaluated, as well as respiration contributions to total carbon balance. Two main components were identified as filling the gap between leaf and whole plant WUE: the large effect of leaf position on daily carbon gain and water loss and the large flux of carbon losses by dark respiration. These results show that WUE evaluation among genotypes or treatments needs to be revised.

A finger leaf design for dual layer MLCs

International Nuclear Information System (INIS)

Cui Weijie; Dai Jianrong

2010-01-01

Objective: To introduce a finger leaf design that is applied to dual layer MLCs. Methods: An optimization model was firstly constructed to describe the problem of determining leaf end shapes,and the corresponding problems were then solved by the simplex search method or the simulated annealing technique. Optimal parameters for arc shapes of leaf end projections were obtained, and a comparison was done between optimized MLCs and conventional MLCs in terms of field conformity. The optimization process was based on 634 target fields selected from the patient data base of a treatment planning system. Areas of these fields ranged from 20.0 to 602.7 cm with a mean and its standard deviation of (125.7 ± 0.0) cm 2 . Results: The optimized leaf end shapes projected to the isocenter plane were semicircles. With the finger leaf design, the total area of discrepancy regions between MLC fields and target fields was reduced by 32.3%. Conclusions: The finger leaf design improves the conformity of the MLC shaped fields to the desired target fields. (authors)

Leaf Wetness within a Lily Canopy

NARCIS (Netherlands)

Jacobs, A.F.G.; Heusinkveld, B.G.; Klok, E.J.

2005-01-01

A wetness duration experiment was carried out within a lily field situated adjacent to coastal dunes in the Netherlands. A within-canopy model was applied to simulate leaf wetness in three layers, with equal leaf area indices, within the canopy. This simulation model is an extension of an existing

How Does Temperature Impact Leaf Size and Shape in Four Woody Dicot Species? Testing the Assumptions of Leaf Physiognomy-Climate Models

Science.gov (United States)

McKee, M.; Royer, D. L.

2017-12-01

The physiognomy (size and shape) of fossilized leaves has been used to reconstruct the mean annual temperature of ancient environments. Colder temperatures often select for larger and more abundant leaf teeth—serrated edges on leaf margins—as well as a greater degree of leaf dissection. However, to be able to accurately predict paleotemperature from the morphology of fossilized leaves, leaves must be able to react quickly and in a predictable manner to changes in temperature. We examined the extent to which temperature affects leaf morphology in four tree species: Carpinus caroliniana, Acer negundo, Ilex opaca, and Ostrya virginiana. Saplings of these species were grown in two growth cabinets under contrasting temperatures (17 and 25 °C). Compared to the cool treatment, in the warm treatment Carpinus caroliniana leaves had significantly fewer leaf teeth and a lower ratio of total number of leaf teeth to internal perimeter; and Acer negundo leaves had a significantly lower feret diameter ratio (a measure of leaf dissection). In addition, a two-way ANOVA tested the influence of temperature and species on leaf physiognomy. This analysis revealed that all plants, regardless of species, tended to develop more highly dissected leaves with more leaf teeth in the cool treatment. Because the cabinets maintained equivalent moisture, humidity, and CO2 concentration between the two treatments, these results demonstrate that these species could rapidly adapt to changes in temperature. However, not all of the species reacted identically to temperature changes. For example, Acer negundo, Carpinus caroliniana, and Ostrya virginiana all had a higher number of total teeth in the cool treatment compared to the warm treatment, but the opposite was true for Ilex opaca. Our work questions a fundamental assumption common to all models predicting paleotemperature from the physiognomy of fossilized leaves: a given climate will inevitably select for the same leaf physiognomy

Determination of ploidy level and isolation of genes encoding acetyl-CoA carboxylase in Japanese Foxtail (Alopecurus japonicus.

Directory of Open Access Journals (Sweden)

Hongle Xu

Full Text Available Ploidy level is important in biodiversity studies and in developing strategies for isolating important plant genes. Many herbicide-resistant weed species are polyploids, but our understanding of these polyploid weeds is limited. Japanese foxtail, a noxious agricultural grass weed, has evolved herbicide resistance. However, most studies on this weed have ignored the fact that there are multiple copies of target genes. This may complicate the study of resistance mechanisms. Japanese foxtail was found to be a tetraploid by flow cytometer and chromosome counting, two commonly used methods in the determination of ploidy levels. We found that there are two copies of the gene encoding plastidic acetyl-CoA carboxylase (ACCase in Japanese foxtail and all the homologous genes are expressed. Additionally, no difference in ploidy levels or ACCase gene copy numbers was observed between an ACCase-inhibiting herbicide-resistant and a herbicide-sensitive population in this study.

Immunochemical localization of ribulose-1,5-bisphosphate carboxylase in the symbiont-containing gills of Solemya velum (Bivalvia: Mollusca).

Science.gov (United States)

Cavanaugh, C M; Abbott, M S; Veenhuis, M

1988-10-01

The distribution of the Calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase (RbuP(2)Case; EC 4.1.1.39) was examined by using two immunological methods in tissues of Solemya velum, an Atlantic coast bivalve containing putative chemoautotrophic symbionts. Antibodies elicited by the purified large subunit of RbuP(2)Case from tobacco (Nicotiana tabacum) cross-reacted on immunoblots with a protein of similar molecular mass occurring in extracts of the symbiont-containing gill tissue of S. velum. No cross-reactivity was detected in symbiont-free tissue extracts. The antiserum also cross-reacted in immunoblots with proteins of Thiobacillus neapolitanus, a free-living sulfuroxidizing chemoautotroph whose RbuP(2)Case has been well characterized. In protein A-gold immunoelectron microscopy studies, this antiserum consistently labeled the symbionts but not surrounding host gill tissue, indicating that the symbionts are responsible for the RbuP(2)Case activity.

Kinase Associated-1 Domains Drive MARK/PAR1 Kinases to Membrane Targets by Binding Acidic Phospholipids

Energy Technology Data Exchange (ETDEWEB)

Moravcevic, Katarina; Mendrola, Jeannine M.; Schmitz, Karl R.; Wang, Yu-Hsiu; Slochower, David; Janmey, Paul A.; Lemmon, Mark A. (UPENN-MED)

2011-09-28

Phospholipid-binding modules such as PH, C1, and C2 domains play crucial roles in location-dependent regulation of many protein kinases. Here, we identify the KA1 domain (kinase associated-1 domain), found at the C terminus of yeast septin-associated kinases (Kcc4p, Gin4p, and Hsl1p) and human MARK/PAR1 kinases, as a membrane association domain that binds acidic phospholipids. Membrane localization of isolated KA1 domains depends on phosphatidylserine. Using X-ray crystallography, we identified a structurally conserved binding site for anionic phospholipids in KA1 domains from Kcc4p and MARK1. Mutating this site impairs membrane association of both KA1 domains and intact proteins and reveals the importance of phosphatidylserine for bud neck localization of yeast Kcc4p. Our data suggest that KA1 domains contribute to coincidence detection, allowing kinases to bind other regulators (such as septins) only at the membrane surface. These findings have important implications for understanding MARK/PAR1 kinases, which are implicated in Alzheimer's disease, cancer, and autism.

7 CFR 29.2530 - Leaf structure.

Science.gov (United States)

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of...

Importance of Secondary Metabolites for Leaf Beetles (Coleoptera: Chrysomelidae

Directory of Open Access Journals (Sweden)

A. N. EKİZ

2014-06-01

Full Text Available Leaf beetles (Chrysomelidae are one of the most diverse families of herbivorous insects. Many of them are important agricultural pests and cause remarkable loss of crop and money as well. Plant leaves and roots are primary food source of both larva and adults of leaf beetles. Plants produce many secondary metabolites in reaction to herbivore insects. It is a well-known phenomenon that quantity and variety of secondary metabolites in plant leaves may change in response to insect attacks. Herbivore insects have to deal with such defensive secondary chemicals and overcome either by detoxifying or storing them. Accordingly, many specialist herbivores coevolved with their host plant. Certain phenolic glycosides may reduce leaf beetle feeding. Condensed tannins are anti-herbivore defenses against leaf chewing beetles, including leaf beetles. Flavonoid compounds are feeding deterrents for many flea leaf beetles. Cinnamic acid derivatives are other known feeding deterrents for leaf beetles. Secondary metabolites quantity and nutritional quality of host plants are not only important for feeding but also for providing enemy-free space and suitable oviposition sites.

Models for leaf area estimation in dwarf pigeon pea by leaf dimensions

Directory of Open Access Journals (Sweden)

Rafael Vieira Pezzini

2018-03-01

Full Text Available ABSTRACT This study aims to determine the most suitable model to estimate the leaf area of dwarf pigeon pea in function of the leaf central leaflet dimension. Six samplings of 200 leaves were performed in the first experiment, at 36, 42, 50, 56, 64, and 72 days after emergence (DAE. In the second experiment, seven samplings of 200 leaves were performed at 29, 36, 43, 49, 57, 65, and 70 DAE, totaling 2600 leaves. The length (L and width (W of the central leaflet were measured in all leaves composed by left, central, and right leaflets, the product of length times width (LW was calculated, and the leaf area (Y – sum of left, central, and right leaflet areas was determined by digital images. Linear, power, quadratic, and cubic models of Y as function of L, W, and LW were built using data from the second experiment. Leaves from the first experiment were used to validate the models. In dwarf pigeon pea, the linear (Ŷ = – 0.4088 + 1.6669x, R2 = 0.9790 is preferable, but power (Ŷ = 1.6097x1.0065, R2 = 0.9766, quadratic (Ŷ = – 0.3625 + 1.663x + 0.00007x2, R2 = 0.9790, and cubic (Ŷ = 0.7216 + 1.522x + 0.005x2 – 5E–05x3, R2 = 0.9791 models in function of LW are also suitable to estimate the leaf area obtained by digital images. The power model (Ŷ = 5.2508x1.7868, R2 = 0.95 based on the central leaflet width is less laborious because requires only one variable, but it presents accuracy reduction.

SH2/SH3 adaptor proteins can link tyrosine kinases to a Ste20-related protein kinase, HPK1.

Science.gov (United States)

Anafi, M; Kiefer, F; Gish, G D; Mbamalu, G; Iscove, N N; Pawson, T

1997-10-31

Ste20-related protein kinases have been implicated as regulating a range of cellular responses, including stress-activated protein kinase pathways and the control of cytoskeletal architecture. An important issue involves the identities of the upstream signals and regulators that might control the biological functions of mammalian Ste20-related protein kinases. HPK1 is a protein-serine/threonine kinase that possesses a Ste20-like kinase domain, and in transfected cells activates a protein kinase pathway leading to the stress-activated protein kinase SAPK/JNK. Here we have investigated candidate upstream regulators that might interact with HPK1. HPK1 possesses an N-terminal catalytic domain and an extended C-terminal tail with four proline-rich motifs. The SH3 domains of Grb2 bound in vitro to specific proline-rich motifs in the HPK1 tail and functioned synergistically to direct the stable binding of Grb2 to HPK1 in transfected Cos1 cells. Epidermal growth factor (EGF) stimulation did not affect the binding of Grb2 to HPK1 but induced recruitment of the Grb2.HPK1 complex to the autophosphorylated EGF receptor and to the Shc docking protein. Several activated receptor and cytoplasmic tyrosine kinases, including the EGF receptor, stimulated the tyrosine phosphorylation of the HPK1 serine/threonine kinase. These results suggest that HPK1, a mammalian Ste20-related protein-serine/threonine kinase, can potentially associate with protein-tyrosine kinases through interactions mediated by SH2/SH3 adaptors such as Grb2. Such interaction may provide a possible mechanism for cross-talk between distinct biochemical pathways following the activation of tyrosine kinases.

Leveraging multiple datasets for deep leaf counting

OpenAIRE

Dobrescu, Andrei; Giuffrida, Mario Valerio; Tsaftaris, Sotirios A

2017-01-01

The number of leaves a plant has is one of the key traits (phenotypes) describing its development and growth. Here, we propose an automated, deep learning based approach for counting leaves in model rosette plants. While state-of-the-art results on leaf counting with deep learning methods have recently been reported, they obtain the count as a result of leaf segmentation and thus require per-leaf (instance) segmentation to train the models (a rather strong annotation). Instead, our method tre...

Resistance in winter barley against Ramularia leaf spot

DEFF Research Database (Denmark)

Hjortshøj, Rasmus Lund

Ramularia leaf spot is an emerging disease in barley caused by R. collo-cygni. At present little is known about the resistance mechanisms carried out by the host plant to avoid disease development. Nor is the lifecycle of the fungus or its populations structure fully understood. To gain insight....... fulvum-tomato and S. tritici-wheat in order to find modelsystems to enhance interpretation of results from R. collo-cygni-barley interaction. Results from the mapping showed that resistance to Ramularia leaf spot is controlled by a number of QTL’s, some of which co-locate with other physiological traits....... The populations further segregated for physiological leaf spots, a phenomenon related to the leaf damage imposed by Rubellin, although, resistance to physiological leafspots appeared to come from the Ramularia leaf spot susceptible parent. The toxin assay further supported this result as the genotypes susceptible...

Physiological responses of the CAM epiphyte Tillandsia usneoides L. (Bromeliaceae) to variations in light and water supply.

Science.gov (United States)

Haslam, Richard; Borland, Anne; Maxwell, Kate; Griffiths, Howard

2003-06-01

In an effort to understand the mechanisms that sustain rootless atmospheric plants, the modulation of Crassulacean acid metabolism (CAM) in response to variations in irradiance and water supply was investigated in the epiphyte Tillandsia usneoides. Plants were acclimated to three light regimes, i.e. high, intermediate and low, with integrated photon flux densities (PFD) of 14.40, 8.64 and 4.32 mol m-2 d-1 equivalent to an instantaneous PFD of 200, 100, and 50 mumol m-2 s-1, respectively. Daily watering was then withdrawn from half of the plants at each PFD for 7 d prior to sampling. In response to the three PFD treatments, chlorophyll content increased in plants acclimated to lower irradiances. Light response curves using non-invasive measurements of chlorophyll fluorescence demonstrated that photosystem II efficiency (phi PSII) was maintained in high PFD acclimated plants, as they exhibited a larger capacity for non-photochemical dissipation (NPQ) of excess light energy than low PFD acclimated plants. Net CO2 uptake increased in response to higher PFD, reflecting enhanced carboxylation capacity in terms of phosphoenolpyruvate carboxylase (PEPc) and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activities. After water was withdrawn, nocturnal net CO2 uptake and accumulated levels of acidity declined in all PFD treatments, concomitant with increased respiratory recycling of malate. Examining the strategies employed by epiphytes such as T. usneodies to tolerate extreme light and water regimes has demonstrated the importance of physiological mechanisms that allow flexible carboxylation capacity and continued carbon cycling to maintain photosynthetic integrity.

Distinct roles of two anaplerotic pathways in glutamate production induced by biotin limitation in Corynebacterium glutamicum.

Science.gov (United States)

Sato, Hiroki; Orishimo, Keita; Shirai, Tomokazu; Hirasawa, Takashi; Nagahisa, Keisuke; Shimizu, Hiroshi; Wachi, Masaaki

2008-07-01

Corynebacterium glutamicum is a biotin auxotrophic bacterium in which glutamate production is induced under biotin-limited conditions. During glutamate production, anaplerotic reactions catalyzed by phosphoenolpyruvate carboxylase (PEPC) and a biotin-containing enzyme pyruvate carboxylase (PC) are believed to play an important role in supplying oxaloacetate in the tricarboxylic acid cycle. To understand the distinct roles of PEPC and PC on glutamate production by C. glutamicum, we observed glutamate production induced under biotin-limited conditions in the disruptants of the genes encoding PEPC (ppc) and PC (pyc), respectively. The pyc disruptant retained the ability to produce high amounts of glutamate, and lactate was simultaneously produced probably due to the increased intracellular pyruvate levels. On the other hand, the ppc knockout mutant could not produce glutamate. Additionally, glutamate production in the pyc disruptant was enhanced by overexpression of ppc rather than disruption of the lactate dehydrogenase gene (ldh), which is involved in lactate production. Metabolic flux analysis based on the 13C-labeling experiment and measurement of 13C-enrichment in glutamate using nuclear magnetic resonance spectroscopy revealed that the flux for anaplerotic reactions in the pyc disruptant was lower than that in the wild type, concomitantly increasing the flux for lactate formation. Moreover, overexpression of ppc increased this flux in both the pyc disruptant and the wild type. Our results suggest that the PEPC-catalyzed anaplerotic reaction is necessary for glutamate production induced under biotin-limited conditions, because PC is not active during glutamate production, and overexpression of ppc effectively enhances glutamate production under biotin-limited conditions.

The kinase activity of the Ser/Thr kinase BUB1 promotes TGF-β signaling.

Science.gov (United States)

Nyati, Shyam; Schinske-Sebolt, Katrina; Pitchiaya, Sethuramasundaram; Chekhovskiy, Katerina; Chator, Areeb; Chaudhry, Nauman; Dosch, Joseph; Van Dort, Marcian E; Varambally, Sooryanarayana; Kumar-Sinha, Chandan; Nyati, Mukesh Kumar; Ray, Dipankar; Walter, Nils G; Yu, Hongtao; Ross, Brian Dale; Rehemtulla, Alnawaz

2015-01-06

Transforming growth factor-β (TGF-β) signaling regulates cell proliferation and differentiation, which contributes to development and disease. Upon binding TGF-β, the type I receptor (TGFBRI) binds TGFBRII, leading to the activation of the transcription factors SMAD2 and SMAD3. Using an RNA interference screen of the human kinome and a live-cell reporter for TGFBR activity, we identified the kinase BUB1 (budding uninhibited by benzimidazoles-1) as a key mediator of TGF-β signaling. BUB1 interacted with TGFBRI in the presence of TGF-β and promoted the heterodimerization of TGFBRI and TGFBRII. Additionally, BUB1 interacted with TGFBRII, suggesting the formation of a ternary complex. Knocking down BUB1 prevented the recruitment of SMAD3 to the receptor complex, the phosphorylation of SMAD2 and SMAD3 and their interaction with SMAD4, SMAD-dependent transcription, and TGF-β-mediated changes in cellular phenotype including epithelial-mesenchymal transition (EMT), migration, and invasion. Knockdown of BUB1 also impaired noncanonical TGF-β signaling mediated by the kinases AKT and p38 MAPK (mitogen-activated protein kinase). The ability of BUB1 to promote TGF-β signaling depended on the kinase activity of BUB1. A small-molecule inhibitor of the kinase activity of BUB1 (2OH-BNPP1) and a kinase-deficient mutant of BUB1 suppressed TGF-β signaling and formation of the ternary complex in various normal and cancer cell lines. 2OH-BNPP1 administration to mice bearing lung carcinoma xenografts reduced the amount of phosphorylated SMAD2 in tumor tissue. These findings indicated that BUB1 functions as a kinase in the TGF-β pathway in a role beyond its established function in cell cycle regulation and chromosome cohesion. Copyright © 2015, American Association for the Advancement of Science.

A systematic evaluation of protein kinase a-a-kinase anchoring protein interaction motifs

NARCIS (Netherlands)

Burgers, Pepijn P|info:eu-repo/dai/nl/341566551; van der Heyden, Marcel A G; Kok, Bart; Heck, Albert J R|info:eu-repo/dai/nl/105189332; Scholten, Arjen|info:eu-repo/dai/nl/313939780

2015-01-01

Protein kinase A (PKA) in vertebrates is localized to specific locations in the cell via A-kinase anchoring proteins (AKAPs). The regulatory subunits of the four PKA isoforms (RIα, RIβ, RIIα, and RIIβ) each form a homodimer, and their dimerization domain interacts with a small helical region present

A systematic evaluation of protein kinase A-A-kinase anchoring protein interaction motifs

NARCIS (Netherlands)

Burgers, Pepijn P; van der Heyden, MAG; Kok, Bart; Heck, Albert J R; Scholten, Arjen

2015-01-01

Protein kinase A (PKA) in vertebrates is localized to specific locations in the cell via A-kinase anchoring proteins (AKAPs). The regulatory subunits of the four PKA isoforms (RIα, RIβ, RIIα, and RIIβ) each form a homodimer, and their dimerization domain interacts with a small helical region present

[Latitude variation mechanism of leaf traits of Metasequoia glyptostroboides in eastern coastal China].

Science.gov (United States)

Guo, Wei Hong; Wang, Hua; Yu, Mu Kui; Wu, Tong Gui; Han, You Zhi

2017-03-18

We analyzed the rules of Metasequoia glyptostroboides along with latitude, including leaf length, leaf width, leaf perimeter, leaf area, ratio of leaf length to width, specific leaf area (SLA), and leaf dry mass based on eight stands growing at different latitudes in the coastal area of eastern China, as well as their relationships with climatic and soil factors. The results showed that the leaf length, leaf width and leaf perimeter increased with increasing latitude, while the leaf area and SLA firstly increased and then decreased. The mean annual temperature and annual precipitation were the major environmental factors affecting the leaf traits along latitude gradient. With the increase of soil N content, the SLA decreased firstly and then increased, while the leaf mass decreased significantly. With the increase of soil P content, the SLA increased, and the leaf mass decreased significantly.

Endophytic fungi reduce leaf-cutting ant damage to seedlings

Science.gov (United States)

Bittleston, L. S.; Brockmann, F.; Wcislo, W.; Van Bael, S. A.

2011-01-01

Our study examines how the mutualism between Atta colombica leaf-cutting ants and their cultivated fungus is influenced by the presence of diverse foliar endophytic fungi (endophytes) at high densities in tropical leaf tissues. We conducted laboratory choice trials in which ant colonies chose between Cordia alliodora seedlings with high (Ehigh) or low (Elow) densities of endophytes. The Ehigh seedlings contained 5.5 times higher endophyte content and a greater diversity of fungal morphospecies than the Elow treatment, and endophyte content was not correlated with leaf toughness or thickness. Leaf-cutting ants cut over 2.5 times the leaf area from Elow relative to Ehigh seedlings and had a tendency to recruit more ants to Elow plants. Our findings suggest that leaf-cutting ants may incur costs from cutting and processing leaves with high endophyte loads, which could impact Neotropical forests by causing variable damage rates within plant communities. PMID:20610420

Consequences of leaf calibration errors on IMRT delivery

International Nuclear Information System (INIS)

Sastre-Padro, M; Welleweerd, J; Malinen, E; Eilertsen, K; Olsen, D R; Heide, U A van der

2007-01-01

IMRT treatments using multi-leaf collimators may involve a large number of segments in order to spare the organs at risk. When a large proportion of these segments are small, leaf positioning errors may become relevant and have therapeutic consequences. The performance of four head and neck IMRT treatments under eight different cases of leaf positioning errors has been studied. Systematic leaf pair offset errors in the range of ±2.0 mm were introduced, thus modifying the segment sizes of the original IMRT plans. Thirty-six films were irradiated with the original and modified segments. The dose difference and the gamma index (with 2%/2 mm criteria) were used for evaluating the discrepancies between the irradiated films. The median dose differences were linearly related to the simulated leaf pair errors. In the worst case, a 2.0 mm error generated a median dose difference of 1.5%. Following the gamma analysis, two out of the 32 modified plans were not acceptable. In conclusion, small systematic leaf bank positioning errors have a measurable impact on the delivered dose and may have consequences for the therapeutic outcome of IMRT

Generality of leaf trait relationships: A test across six biomes

Energy Technology Data Exchange (ETDEWEB)

Reich, P.B. [Univ. of Minnesota, Saint Paul, MN (United States). Dept. of Forest Resources; Ellsworth, D.S. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science; Walters, M.B. [Michigan State Univ., East Lansing, MI (United States). Dept. of Forestry; Vose, J.M. [Forest Service, Otto, NC (United States). Coweeta Hydrological Lab.; Gresham, C. [Clemson Univ., Georgetown, SC (United States). Baruch Forest Inst.; Volin, J.C. [Florida Atlantic Univ., Davie, FL (United States). Div. of Science; Bowman, W.D. [Inst. of Arctic and Alpine Research, Boulder, CO (United States). Mountain Research Station]|[Univ. of Colorado, Boulder, CO (United States). Dept. of Evolutionary, Population, and Organismic Biology

1999-09-01

Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here the authors address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A{sub max}), leaf diffusive conductance (G{sub S}), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N{sub mass}), SLA, G{sub S}, and A{sub max} were positively related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across sites, species had greater A{sub max} for a given level of G{sub S} and lower SLA for any given leaf life span. Using principal components analysis, most variation among species was explained by an axis related to mass-based leaf traits (A{sub max}, N, and SLA) while a second axis reflected climate, G{sub S}, and other area-based leaf traits.

Effects of some growth regulating applications on leaf yield, raw ...

African Journals Online (AJOL)

This study investigated the effects of repetitive applications of herbagreen (HG), humic acid (HA), combined foliar fertilizer (CFF) and HG+CFF performed in the Müsküle grape variety grafted on 5 BB rootstock on fresh or pickled leaf size and leaf raw cellulose content. HA application increased leaf area and leaf water ...

Patterns of leaf morphology and leaf N content in relation to winter temperatures in three evergreen tree species

Science.gov (United States)

Mediavilla, Sonia; Gallardo-López, Victoria; González-Zurdo, Patricia; Escudero, Alfonso

2012-09-01

The competitive equilibrium between deciduous and perennial species in a new scenario of climate change may depend closely on the productivity of leaves along the different seasons of the year and on the morphological and chemical adaptations required for leaf survival during the different seasons. The aim of the present work was to analyze such adaptations in the leaves of three evergreen species ( Quercus ilex, Q. suber and Pinus pinaster) and their responses to between-site differences in the intensity of winter harshness. We explore the hypothesis that the harshness of winter would contribute to enhancing the leaf traits that allow them to persist under conditions of stress. The results revealed that as winter harshness increases a decrease in leaf size occurs in all three species, together with an increase in the content of nitrogen per unit leaf area and a greater leaf mass per unit area, which seems to be achieved only through increased thickness, with no associated changes in density. P. pinaster was the species with the most intense response to the harshening of winter conditions, undergoing a more marked thickening of its needles than the two Quercus species. Our findings thus suggest that lower winter temperatures involve an increase in the cost of leaf production of evergreen species, which must be taken into account in the estimation of the final cost and benefit balance of evergreens. Such cost increases would be more pronounced for those species that, like P. pinaster, show a stronger response to the winter cold.

Dynamics of vacuum-sealed, double-leaf partitions

Science.gov (United States)

Kavanaugh, Joshua Stephen

The goal of this research is to investigate the feasibility and potential effectiveness of using vacuum-sealed, double-leaf partitions for applications in noise control. Substantial work has been done previously on double-leaf partitions where the acoustics of the inner chamber and mechanical vibrations of structural supports are passively and actively controlled. The work presented here is unique in that the proposed system aims to eliminate the need for active acoustic control of transmitted acoustic energy by removing all the air between the two panels of the double partition. Therefore, the only remaining energy paths would be along the boundary and at the points where there are intermediate structural supports connecting the two panels. The eventual goal of the research is to develop a high-loss double-leaf partition that simplifies active control by removing the need for control of the air cavity and channeling all the energy into discrete structural paths. The work presented here is a first step towards the goal of designing a high-loss, actively-controlled double-leaf partition with an air-evacuated inner chamber. One experiment is conducted to investigate the effects of various levels of vacuum on the response of a double-leaf partition whose panels are mechanically coupled only at the boundary. Another experiment is conducted which investigates the effect of changing the stiffness of an intermediate support coupling the two panels of a double-leaf partition in which a vacuum has been applied to the inner cavity. The available equipment was able to maintain a 99% vacuum between the panels. Both experiments are accompanied by analytical models used to investigate the importance of various dynamic parameters. Results show that the vacuum-sealed system shows some potential for increased transmission loss, primarily by the changing the natural frequencies of the double-leaf partition.

Predicting tropical plant physiology from leaf and canopy spectroscopy.

Science.gov (United States)

Doughty, Christopher E; Asner, Gregory P; Martin, Roberta E

2011-02-01

A broad regional understanding of tropical forest leaf photosynthesis has long been a goal for tropical forest ecologists, but it has remained elusive due to difficult canopy access and high species diversity. Here we develop an empirical model to predict sunlit, light-saturated, tropical leaf photosynthesis using leaf and simulated canopy spectra. To develop this model, we used partial least squares (PLS) analysis on three tropical forest datasets (159 species), two in Hawaii and one at the biosphere 2 laboratory (B2L). For each species, we measured light-saturated photosynthesis (A), light and CO(2) saturated photosynthesis (A(max)), respiration (R), leaf transmittance and reflectance spectra (400-2,500 nm), leaf nitrogen, chlorophyll a and b, carotenoids, and leaf mass per area (LMA). The model best predicted A [r(2) = 0.74, root mean square error (RMSE) = 2.9 μmol m(-2) s(-1))] followed by R (r(2) = 0.48), and A(max) (r(2) = 0.47). We combined leaf reflectance and transmittance with a canopy radiative transfer model to simulate top-of-canopy reflectance and found that canopy spectra are a better predictor of A (RMSE = 2.5 ± 0.07 μmol m(-2) s(-1)) than are leaf spectra. The results indicate the potential for this technique to be used with high-fidelity imaging spectrometers to remotely sense tropical forest canopy photosynthesis.

The Effect of Leaf Stacking on Leaf Reflectance and Vegetation Indices Measured by Contact Probe during the Season

Czech Academy of Sciences Publication Activity Database

Neuwirthová, E.; Lhotáková, Z.; Albrechtová, Jana

2017-01-01

Roč. 17, č. 6 (2017), s. 1-23, č. článku 1202. ISSN 1424-8220 Institutional support: RVO:67985939 Keywords : broadleaved trees * leaf optical properties * leaf traits Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 2.677, year: 2016

Phosphorylation of nm23/nucleoside diphosphate kinase by casein kinase 2 in vitro

DEFF Research Database (Denmark)

Engel, M; Issinger, O G; Lascu, I

1994-01-01

We have investigated phosphorylation of human nucleoside diphosphate kinase (NDPK) and of homologous NDPK from different species by human casein kinase 2 (CK-2). The human NDPK isotypes A and B were phosphorylated by CK-2 in vitro both when the purified proteins and total lysate of HL-60 leukemia...

BOREAS TE-9 NSA Leaf Chlorophyll Density

Science.gov (United States)

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

2000-01-01

The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Involvement of adenosine monophosphate-activated protein kinase in the influence of timed high-fat evening diet on the hepatic clock and lipogenic gene expression in mice.

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Huang, Yan; Zhu, Zengyan; Xie, Meilin; Xue, Jie

2015-09-01

A high-fat diet may result in changes in hepatic clock gene expression, but potential mechanisms are not yet elucidated. Adenosine monophosphate-activated protein kinase (AMPK) is a serine/threonine protein kinase that is recognized as a key regulator of energy metabolism and certain clock genes. Therefore, we hypothesized that AMPK may be involved in the alteration of hepatic clock gene expression under a high-fat environment. This study aimed to examine the effects of timed high-fat evening diet on the activity of hepatic AMPK, clock genes, and lipogenic genes. Mice with hyperlipidemic fatty livers were induced by orally administering high-fat milk via gavage every evening (19:00-20:00) for 6 weeks. Results showed that timed high-fat diet in the evening not only decreased the hepatic AMPK protein expression and activity but also disturbed its circadian rhythm. Accordingly, the hepatic clock genes, including clock, brain-muscle-Arnt-like 1, cryptochrome 2, and period 2, exhibited prominent changes in their expression rhythms and/or amplitudes. The diurnal rhythms of the messenger RNA expression of peroxisome proliferator-activated receptorα, acetyl-CoA carboxylase 1α, and carnitine palmitoyltransferase 1 were also disrupted; the amplitude of peroxisome proliferator-activated receptorγcoactivator 1α was significantly decreased at 3 time points, and fatty liver was observed. These findings demonstrate that timed high-fat diet at night can change hepatic AMPK protein levels, activity, and circadian rhythm, which may subsequently alter the circadian expression of several hepatic clock genes and finally result in the disorder of hepatic lipogenic gene expression and the formation of fatty liver. Copyright © 2015 Elsevier Inc. All rights reserved.

Silver nano fabrication using leaf disc of Passiflora foetida Linn

Science.gov (United States)

Lade, Bipin D.; Patil, Anita S.

2017-06-01

The main purpose of the experiment is to develop a greener low cost SNP fabrication steps using factories of secondary metabolites from Passiflora leaf extract. Here, the leaf extraction process is omitted, and instead a leaf disc was used for stable SNP fabricated by optimizing parameters such as a circular leaf disc of 2 cm (1, 2, 3, 4, 5) instead of leaf extract and grade of pH (7, 8, 9, 11). The SNP synthesis reaction is tried under room temperature, sun, UV and dark condition. The leaf disc preparation steps are also discussed in details. The SNP obtained using (1 mM: 100 ml AgNO3+ singular leaf disc: pH 9, 11) is applied against featured room temperature and sun condition. The UV spectroscopic analysis confirms that sun rays synthesized SNP yields stable nano particles. The FTIR analysis confirms a large number of functional groups such as alkanes, alkyne, amines, aliphatic amine, carboxylic acid; nitro-compound, alcohol, saturated aldehyde and phenols involved in reduction of silver salt to zero valent ions. The leaf disc mediated synthesis of silver nanoparticles, minimizes leaf extract preparation step and eligible for stable SNP synthesis. The methods sun and room temperature based nano particles synthesized within 10 min would be use certainly for antimicrobial activity.

Reading the Leaves: A Comparison of Leaf Rank and Automated Areole Measurement for Quantifying Aspects of Leaf Venation

Directory of Open Access Journals (Sweden)

Walton A. Green

2014-08-01

Full Text Available The reticulate venation that is characteristic of a dicot leaf has excited interest from systematists for more than a century, and from physiological and developmental botanists for decades. The tools of digital image acquisition and computer image analysis, however, are only now approaching the sophistication needed to quantify aspects of the venation network found in real leaves quickly, easily, accurately, and reliably enough to produce biologically meaningful data. In this paper, we examine 120 leaves distributed across vascular plants (representing 118 genera and 80 families using two approaches: a semiquantitative scoring system called “leaf ranking,” devised by the late Leo Hickey, and an automated image-analysis protocol. In the process of comparing these approaches, we review some methodological issues that arise in trying to quantify a vein network, and discuss the strengths and weaknesses of automatic data collection and human pattern recognition. We conclude that subjective leaf rank provides a relatively consistent, semiquantitative measure of areole size among other variables; that modal areole size is generally consistent across large sections of a leaf lamina; and that both approaches—semiquantitative, subjective scoring; and fully quantitative, automated measurement—have appropriate places in the study of leaf venation.

Up-scaling of water use efficiency from leaf to canopy as based on leaf gas exchange relationships and the modeled in-canopy light distribution

DEFF Research Database (Denmark)

Linderson, Maj-Lena; Mikkelsen, Teis Nørgaard; Ibrom, Andreas

2012-01-01

The aim of this study was to evaluate the extent to which water use efficiency (WUE) at leaf scale can be used to assess WUE at canopy scale, leaf WUE being assumed to be a constant function of vapor pressure deficit and to thus not be dependent upon other environmental factors or varying leaf...... properties. Leaf WUE and its variability and dependencies were assessed using leafgas-exchange measurements obtained during two growing seasons, 1999 and 2000, at the Soroe beech forest study site on Zealand in Denmark. It was found that the VPD-normalized leaf WUE, WUEnormleaf, although dependent...

Enterococcus faecalis phosphomevalonate kinase

Science.gov (United States)

Doun, Stephanie S.; Burgner, John W.; Briggs, Scott D.; Rodwell, Victor W.

2005-01-01

The six enzymes of the mevalonate pathway of isopentenyl diphosphate biosynthesis represent potential for addressing a pressing human health concern, the development of antibiotics against resistant strains of the Gram-positive streptococci. We previously characterized the first four of the mevalonate pathway enzymes of Enterococcus faecalis, and here characterize the fifth, phosphomevalonate kinase (E.C. 2.7.4.2). E. faecalis genomic DNA and the polymerase chain reaction were used to clone DNA thought to encode phosphomevalonate kinase into pET28b(+). Double-stranded DNA sequencing verified the sequence of the recombinant gene. The encoded N-terminal hexahistidine-tagged protein was expressed in Escherichia coli with induction by isopropylthiogalactoside and purified by Ni++ affinity chromatography, yield 20 mg protein per liter. Analysis of the purified protein by MALDI-TOF mass spectrometry established it as E. faecalis phosphomevalonate kinase. Analytical ultracentrifugation revealed that the kinase exists in solution primarily as a dimer. Assay for phosphomevalonate kinase activity used pyruvate kinase and lactate dehydrogenase to couple the formation of ADP to the oxidation of NADH. Optimal activity occurred at pH 8.0 and at 37°C. The activation energy was ~5.6 kcal/mol. Activity with Mn++, the preferred cation, was optimal at about 4 mM. Relative rates using different phosphoryl donors were 100 (ATP), 3.6 (GTP), 1.6 (TTP), and 0.4 (CTP). Km values were 0.17 mM for ATP and 0.19 mM for (R,S)-5-phosphomevalonate. The specific activity of the purified enzyme was 3.9 μmol substrate converted per minute per milligram protein. Applications to an immobilized enzyme bioreactor and to drug screening and design are discussed. PMID:15802646

Physiological characteristics and metabolomics of transgenic wheat containing the maize C4 phosphoenolpyruvate carboxylase (PEPC) gene under high temperature stress.

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