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Sample records for leaf phosphoenolpyruvate carboxylase-kinase

  1. Involvement of phospholipase D and phosphatidic acid in the light-dependent up-regulation of sorghum leaf phosphoenolpyruvate carboxylase-kinase

    PubMed Central

    Monreal, José Antonio; López-Baena, Francisco Javier; Vidal, Jean; Echevarría, Cristina; García-Mauriño, Sofía

    2010-01-01

    The photosynthetic phosphoenolpyruvate carboxylase (C4-PEPC) is regulated by phosphorylation by a phosphoenolpyruvate carboxylase kinase (PEPC-k). In Digitaria sanguinalis mesophyll protoplasts, this light-mediated transduction cascade principally requires a phosphoinositide-specific phospholipase C (PI-PLC) and a Ca2+-dependent step. The present study investigates the cascade components at the higher integrated level of Sorghum bicolor leaf discs and leaves. PEPC-k up-regulation required light and photosynthetic electron transport. However, the PI-PLC inhibitor U-73122 and inhibitors of calcium release from intracellular stores only partially blocked this process. Analysis of [32P]phosphate-labelled phospholipids showed a light-dependent increase in phospholipase D (PLD) activity. Treatment of leaf discs with n-butanol, which decreases the formation of phosphatidic acid (PA) by PLD, led to the partial inhibition of the C4-PEPC phosphorylation, suggesting the participation of PLD/PA in the signalling cascade. PPCK1 gene expression was strictly light-dependent. Addition of neomycin or n-butanol decreased, and a combination of both inhibitors markedly reduced PPCK1 expression and the concomitant rise in PEPC-k activity. The calcium/calmodulin antagonist W7 blocked the light-dependent up-regulation of PEPC-k, pointing to a Ca2+-dependent protein kinase (CDPK) integrating both second messengers, calcium and PA, which were shown to increase the activity of sorghum CDPK. PMID:20410319

  2. Phosphoenolpyruvate Carboxylase Kinase in Tobacco Leaves Is Activated by Light in a Similar but Not Identical Way as in Maize.

    PubMed Central

    Li, B.; Zhang, X. Q.; Chollet, R.

    1996-01-01

    We have previously reported the partial purification of a Ca2+- independent phosphoenolpyruvate carboxylase (PEPC) protein-serine/threonine kinase (PEPC-PK) from illuminated leaves of N-sufficient tobacco (Nicotiana tabacum L.) plants (Y.-H. Wang, R. Chollet [1993] FEBS Lett 328: 215-218). We now report that this C3 PEPC-kinase is reversibly light activated in vivo in a time-dependent manner. As the kinase becomes light activated, the activity and L-malate sensitivity of its target protein increases and decreases, respectively. The light activation of tobacco PEPC-PK is prevented by pretreatment of detached leaves with various photosynthesis and cytosolic protein-synthesis inhibitors. Similarly, specific inhibitors of glutamine synthetase block the light activation of tobacco leaf PEPC-kinase under both photorespiratory and nonphotorespiratory conditions. This striking effect is partially and specifically reversed by exogenous glutamine, whereas it has no apparent effect on the light activation of the maize (Zea mays L.) leaf kinase. Using an in situ "activity-gel" phosphorylation assay, we have identified two major Ca2+-independent PEPC-kinase catalytic polypeptides in illuminated tobacco leaves that have the same molecular masses (approximately 30 and 37 kD) as found in illuminated maize leaves. Collectively, these results indicate that the phosphorylation of PEPC in N-sufficient leaves of tobacco (C3) and maize (C4) is regulated through similar but not identical light-signal transduction pathways. PMID:12226305

  3. Metabolite Control Overrides Circadian Regulation of Phosphoenolpyruvate Carboxylase Kinase and CO(2) Fixation in Crassulacean Acid Metabolism.

    PubMed

    Borland; Hartwell; Jenkins; Wilkins; Nimmo

    1999-11-01

    Phosphoenolpyruvate carboxylase (PEPc) catalyzes the primary fixation of CO(2) in Crassulacean acid metabolism plants. Flux through the enzyme is regulated by reversible phosphorylation. PEPc kinase is controlled by changes in the level of its translatable mRNA in response to a circadian rhythm. The physiological significance of changes in the levels of PEPc-kinase-translatable mRNA and the involvement of metabolites in control of the kinase was investigated by subjecting Kalanchoë daigremontiana leaves to anaerobic conditions at night to modulate the magnitude of malate accumulation, or to a rise in temperature at night to increase the efflux of malate from vacuole to cytosol. Changes in CO(2) fixation and PEPc kinase activity reflected those in kinase mRNA. The highest rates of CO(2) fixation and levels of kinase mRNA were observed in leaves subjected to anaerobic treatment for the first half of the night and then transferred to ambient air. In leaves subjected to anaerobic treatment overnight and transferred to ambient air at the start of the day, PEPc-kinase-translatable mRNA and activity, the phosphorylation state of PEPc, and fixation of atmospheric CO(2) were significantly higher than those for control leaves for the first 3 h of the light period. A nighttime temperature increase from 19 degrees C to 27 degrees C led to a rapid reduction in kinase mRNA and activity; however, this was not observed in leaves in which malate accumulation had been prevented by anaerobic treatment. These data are consistent with the hypothesis that a high concentration of malate reduces both kinase mRNA and the accumulation of the kinase itself. PMID:10557237

  4. Photocontrol of Sorghum Leaf Phosphoenolpyruvate Carboxylase 1

    PubMed Central

    Thomas, Martine; Crétin, Claude; Keryer, Eliane; Vidal, Jean; Gadal, Pierre

    1987-01-01

    The mechanism underlying the light effect on phosphoenolpyruvate carboxylase (PEPC) from the C4 plant sorghum (Sorghum vulgare Pers., var Tamaran) leaves was investigated. Following exposure to light a new isozyme of PEPC, specific for the green leaf and responsible for primary CO2 fixation in photosynthesis, was established. Northern blot experiments revealed the presence of PEPC mRNA showing a molecular weight of 3.4 kilobases. During the greening process, concomitant to enzyme activity, PEPC protein and PEPC messenger RNA amounts increased considerably. This photoresponse was shown to be under phytochrome control. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 PMID:16665664

  5. Inactivation of Maize Leaf Phosphoenolpyruvate Carboxylase by the Binding to Chloroplast Membranes 1

    PubMed Central

    Wu, Min-Xian; Wedding, Randolph T.

    1992-01-01

    Phosphoenolpyruvate carboxylase (PEPC) purified from maize (Zea mays L.) leaves associates with maize leaf chloroplast membrane in vitro. The binding of PEPC to the membrane results in enzyme inactivation. A protein isolated from a maize leaf chloroplast membrane preparation inactivated PEPC. Treatment with membrane preparation or with partially purified inactivating protein accelerates PEPC inactivation at low temperature (4°C). Interaction of PEPC with chloroplast membrane or inactivating protein may inactivate the enzyme by influencing dissociation of the enzyme active tetramer. PMID:16652972

  6. Light Induction of Phosphoenolpyruvate Carboxylase in Etiolated Maize Leaf Tissue 1

    PubMed Central

    Hayakawa, Shinobu; Matsunaga, Kazumi; Sugiyama, Tatsuo

    1981-01-01

    An antibody for phosphoenolpyruvate carboxylase was used to isolate and to quantitate the enzyme from greening maize (cv. KOU 6) leaves. The increase in enzyme activity during greening was due to de novo synthesis, which was paralleled by increases in enzyme protein and incorporation of leucine. The light-induced activity was due to one specific isoenzyme. The action spectrum for enzyme synthesis had red and blue peaks. Images PMID:16661613

  7. Serine-15 is the regulatory seryl-phosphorylation site in C sub 4 -leaf phosphoenolpyruvate carboxylase (PEPCase) from maize

    SciTech Connect

    Jiao, Jinan; Chollet, R. )

    1990-05-01

    The {sup 32}P-labeled regulatory site phosphopeptide was purified from a tryptic digest of in vitro phosphorylated/activated dark-form PEPCase by metal ion affinity and reversed-phase chromatography and subjected to automated Edman degradation analysis. The amino acid sequence of this phosphoseryl peptide is His-His-Ser(P)-Ile-Asp-Ala-Gln-Leu-Arg. This nonapeptide, which corresponds exactly to residues 13-21 in the deduced primary sequence of the maize leaf carboxylase, is far removed from a recently identified active-site cysteine (Cys-553) in the C-terminal region of the primary structure. Comparative analysis of the deduced N-terminal sequences of C{sub 3}, C{sub 4}, and CAM leaf PEPCases suggests that the motif of Lys/Arg-X-X-Ser is an important structural requirement of the C{sub 4}- and CAM-leaf protein-serine kinases.

  8. The Importance of the Strictly Conserved, C-terminal Glycine Residue in Phosphoenolpyruvate Carboxylase for Overall Catalysis: Mutagenesis and Truncation of GLY-961 in the Sorghum C4 Leaf Isoform

    SciTech Connect

    Xu,W.; Ahmed, S.; Moriyama, H.; Chollet, R.

    2006-01-01

    Phosphoenolpyruvate carboxylase (PEPC) is a 'multifaceted', allosteric enzyme involved in C4 acid metabolism in green plants/microalgae and prokaryotes. Before the elucidation of the three-dimensional structures of maize C4 leaf and Escherichia coli PEPC, our truncation analysis of the sorghum C4 homologue revealed important roles for the enzyme's C-terminal {alpha}-helix and its appended QNTG{sup 961} tetrapeptide in polypeptide stability and overall catalysis, respectively. Collectively, these functional and structural observations implicate the importance of the PEPC C-terminal tetrapeptide for both catalysis and negative allosteric regulation. We have now more finely dissected this element of PEPC structure-function by modification of the absolutely conserved C-terminal glycine of the sorghum C4 isoform by site-specific mutagenesis (G961(A/V/D)) and truncation ({Delta}C1/C4). Although the C4 polypeptide failed to accumulate in a PEPC{sup -} strain (XH11) of E. coli transformed with the Asp mutant, the other variants were produced at wild-type levels. Although neither of these four mutants displayed an apparent destabilization of the purified PEPC homotetramer, all were compromised catalytically in vivo and in vitro. Functional complementation of XH11 cells under selective growth conditions was restricted progressively by the Ala, {Delta}C1 and Val, and {Delta}C4 modifications. Likewise, steady-state kinetic analysis of the purified mutant enzymes revealed corresponding negative trends in k{sub cat} and k{sub cat}/K0.5 (phosphoenolpyruvate) but not in K{sub 0.5} or the Hill coefficient. Homology modeling of these sorghum C-terminal variants against the structure of the closely related maize C4 isoform predicted perturbations in active-site molecular cavities and/or ion-pairing with essential, invariant Arg-638. These collective observations reveal that even a modest, neutral alteration of the PEPC C-terminal hydrogen atom side chain is detrimental to enzyme

  9. Phosphoenolpyruvate metabolism in Jerusalem artichoke mitochondria.

    PubMed

    de Bari, Lidia; Valenti, Daniela; Pizzuto, Roberto; Atlante, Anna; Passarella, Salvatore

    2007-04-01

    We report here initial studies on phosphoenolpyruvate metabolism in coupled mitochondria isolated from Jerusalem artichoke tubers. It was found that: (1) phosphoenolpyruvate can be metabolized by Jerusalem artichoke mitochondria by virtue of the presence of the mitochondrial pyruvate kinase, shown both immunologically and functionally, located in the inner mitochondrial compartments and distinct from the cytosolic pyruvate kinase as shown by the different pH and inhibition profiles. (2) Jerusalem artichoke mitochondria can take up externally added phosphoenolpyruvate in a proton compensated manner, in a carrier-mediated process which was investigated by measuring fluorimetrically the oxidation of intramitochondrial pyridine nucleotide which occurs as a result of phosphoenolpyruvate uptake and alternative oxidase activation. (3) The addition of phosphoenolpyruvate causes pyruvate and ATP production, as monitored via HPLC, with their efflux into the extramitochondrial phase investigated fluorimetrically. Such an efflux occurs via the putative phosphoenolpyruvate/pyruvate and phosphoenolpyruvate/ATP antiporters, which differ from each other and from the pyruvate and the adenine nucleotide carriers, in the light of the different sensitivity to non-penetrant compounds. These carriers were shown to regulate the rate of efflux of both pyruvate and ATP. The appearance of citrate and oxaloacetate outside mitochondria was also found as a result of phosphoenolpyruvate addition. PMID:17418088

  10. Comparative Characterization of Phosphoenolpyruvate Carboxylase in C3, C4, and C3-C4 Intermediate Panicum Species 1

    PubMed Central

    Holaday, A. Scott; Black, Clanton C.

    1981-01-01

    Various properties of phosphoenolpyruvate carboxylases were compared in leaf preparations from C3-C4 intermediate, C3, and C4Panicum species. Values of Vmax in micromoles per milligram chlorophyll per hour at pH 8.3 were 57 to 75 for the enzyme from Panicum milioides, Panicum schenckii, and Panicum decipiens (all C3-C4). The values for Panicum laxum (C3) and Panicum prionitis (C4) were 20 to 40 and 952 to 1374, respectively. The Vmax values did not change at pH 7.3 except for the C4 value, which increased about 24%. At pH 8.3, the phosphoenolpyruvate carboxylases from C3 and C3-C4 species had slightly higher Km HCO3− and lower K′ phosphoenolpyruvate values than did the C4 enzyme. With each species at pH 7.3, all K′ phosphoenolpyruvate values were 2- to 4-fold greater. The enzyme from all species was inhibited 85 to 90% by 1 millimolar malate at rate-limiting phosphoenolpyruvate and Mg2+ levels. With low levels of malate, 0.2 millimolar, the rate curve with respect to phosphoenolpyruvate was distinctly sigmoidal, and the inhibition was not eliminated at 5 millimolar phosphoenolpyruvate. Malate at 10 millimolar protected all phosphoenolpyruvate carboxylases from inactivation at 55 C at pH 5.5, but not at pH 8.3. Aspartate did not protect well. When incubated at 37 C at pH 8.3 without phosphoenolpyruvate, but with HCO3−, the enzyme from several C4 grasses lost 92 to 98% of the initial activity after 4 minutes, whereas the enzymes from C3 and C3-C4Panicum species retained 60 to 70% of their activities. In contrast, 5 millimolar phosphoenolpyruvate stabilized the enzyme at 37 C in all plant extracts. The phosphoenolpyruvate carboxylase from C3-C4 intermediate Panicum species has properties most similar to the enzyme from C3Panicum species. The higher leaf activity of the enzyme from the intermediate plants than from C3 species is not due to any unusual property assayed other than a higher Vmax. PMID:16661669

  11. Phosphoenolpyruvate Carboxykinase in Plants Exhibiting Crassulacean Acid Metabolism 1

    PubMed Central

    Dittrich, P.; Campbell, Wilbur H.; Black, C. C.

    1973-01-01

    Phosphoenolpyruvate carboxykinase has been found in significant activities in a number of plants exhibiting Crassulacean acid metabolism. Thirty-five species were surveyed for phosphoenolpyruvate carboxykinase, phosphoenolpyruvate carboxylase, ribulose diphosphate carboxylase, malic enzyme, and malate dehydrogenase (NAD). Plants which showed high activities of malic enzyme contained no detectable phosphoenolpyruvate carboxykinase, while plants with high activities of the latter enzyme contained little malic enzyme. It is proposed that phosphoenolpyruvate carboxykinase acts as a decarboxylase during the light period, furnishing CO2 for the pentose cycle and phosphoenolpyruvate for gluconeogenesis. Some properties of phosphoenolpyruvate carboxykinase in crude extracts of pineapple leaves were investigated. The enzyme required Mn2+, Mg2+, and ATP for maximum activity. About 60% of the activity could be pelleted, along with chloroplasts and mitochondria, in extracts from leaves kept in the dark overnight. PMID:16658562

  12. Estimation of phosphoenolpyruvate carboxylation mediated by phosphoenolpyruvate carboxykinase (PCK) in engineered Escherichia coli having high ATP.

    PubMed

    Lee, Hyo Jung; Kim, Hye-Jung; Seo, Jiyoon; Na, Yoon Ah; Lee, Jiyeon; Lee, Joo-Young; Kim, Pil

    2013-06-10

    We have previously reported that phosphoenolpyruvate carboxykinase (PCK) overexpression under glycolytic conditions enables Escherichia coli to harbor a high intracellular ATP pool resulting in enhanced recombinant protein synthesis. To estimate how much PCK-mediated phosphoenolpyruvate (PEP) carboxylation is contributed to the ATP increase under engineered conditions, the kinetics of PEP carboxylation by PCK and substrate competing phosphoenolpyruvate carboxylase (PPC) were measured using recombinant enzymes. The PEP carboxylation catalytic efficiency (kcat/Km) of the recombinant PCK was 660mM(-1)min(-1), whereas that of the recombinant PPC was 1500mM(-1)min(-1). Under the presence of known allosteric effectors (fructose 1,6-bisphosphate, acetyl-CoA, ATP, malate, and aspartate) close to in vivo conditions, the catalytic efficiency of PCK-mediated PEP carboxylation (84mM(-1)min(-1)) was 28-folds lower than that of PPC (2370mM(-1)min(-1)). To verify the above results, an E. coli strain expressing native PCK and PPC under control of identical promoter was constructed by replacing PCK promoter region with that of PPC in chromosome. The native PCK activity (33nmol/mg-proteinmin) was 5-folds lower than PPC activity (160nmol/mg-proteinmin) in the cell extract from the promoter-exchanged strain. Intracellular modifications of ATP concentration by PCK activity and the consequences for biotechnology are further discussed. PMID:23683699

  13. Role of Phosphoenolpyruvate Carboxylation in Acetobacter xylinum

    PubMed Central

    Benziman, Moshe

    1969-01-01

    Glucose-grown cells of Acetobacter xylinum oxidized acetate only when the reaction mixture was supplemented with catalytic quantities of glucose or intermediates of the citrate cycle. Extracts, prepared by sonic treatment, catalyzed the formation of oxalacetate when incubated with phosphoenolpyruvate (PEP) and bicarbonate. Oxalacetate was not formed in the presence of pyruvate plus adenosine triphosphate. The ability to promote carboxylation of PEP was lower in succinate-grown cells than in glucose-grown cells. PEP carboxylase, partially purified from extracts by ammonium sulfate fractionation, catalyzed the stoichiometric formation of oxalacetate and inorganic phosphate from PEP and bicarbonate. The enzyme was not affected by acetyl-coenzyme A or inorganic phosphate. It was inhibited by adenosine diphosphate in a manner competitive with PEP (K1 = 1.3 mm) and by dicarboxylic acids of the citrate cycle; of these, succinate was the most potent inhibitor. It is suggested that the physiological role of PEP carboxylase in A. xylinum is to affect the net formation of C4 acids from C3 precursors, which are essential for the maintainance of the citrate cycle during growth on glucose. The relationship of PEP carboxylase to other enzyme systems metabolizing PEP and oxalacetate in A. xylinum is discussed. PMID:5788692

  14. The regulation of phosphoenolpyruvate synthesis in pigeon liver

    PubMed Central

    Gevers, W.

    1967-01-01

    1. The intracellular location and maximal activities of enzymes involved in phosphoenolpyruvate synthesis have been investigated in pigeon liver. Enolase and pyruvate kinase were cytoplasmic, and the activities were 50–60 and 180–210μmoles/min./g. dry wt. at 25° respectively. Phosphoenolpyruvate carboxykinase was present exclusively, and nucleoside diphosphokinase predominantly, in the mitochondria; the particles had to be disrupted to elicit maximal activities, which were 27–33 and 400–600μmoles/min./g. dry wt. at 25° respectively. The activities of all four enzymes did not change significantly during 48hr. of starvation. 2. Conditions for incubation of washed isolated mitochondria were established, to give high rates of synthesis of phosphoenolpyruvate, linear with time and proportional to mitochondrial concentration. Inorganic phosphate and added adenine nucleotides were stimulatory, whereas added Mg2+ inhibited, partly owing to activation of contaminant pyruvate kinase. Phosphoenolpyruvate formation occurred from oxaloacetate, malate, fumarate, succinate, α-oxoglutarate and citrate, in decreasing order of effectiveness. 3. The steady-state ATP/ADP ratio of mitochondrial suspensions was decreased in the presence of added 2·5mm-Mg2+ (owing to stimulation of adenylate kinase and possibly of an adenosine triphosphatase), 0·5mm-Ca2+ or 0·4mm-dinitrophenol. In each case the rate of substrate removal and oxygen uptake was increased, whereas phosphoenolpyruvate synthesis was inhibited. Citrate formation was enhanced, owing to de-inhibition of citrate synthase. These effects were not primarily related to changes in the oxaloacetate concentration. 4. Both phosphoenolpyruvate carboxykinase and nucleoside diphosphokinase were active within the atractylosidesensitive barrier to the mitochondrial metabolism of added adenine nucleotides. There was no correlation between the rate of substrate-level phosphorylation associated with the oxidation of

  15. Phosphoenolpyruvate carboxykinase and pyruvate carboxylase in developing rat liver

    PubMed Central

    Ballard, F. J.; Hanson, R. W.

    1967-01-01

    1. Phosphoenolpyruvate carboxykinase and pyruvate carboxylase were measured in foetal, newborn and adult rat liver extracts by a radiochemical assay involving the fixation of [14C]bicarbonate. 2. Pyruvate-carboxylase activity in both foetal and adult liver occurs mainly in mitochondrial and nuclear fractions, with about 10% of the activity in the cytoplasm. 3. Similar studies of the intracellular distribution of phosphoenolpyruvate carboxykinase show that more than 90% of the activity is in the cytoplasm. However, in the 17-day foetal liver about 90% of the activity is in mitochondria and nuclei. 4. Pyruvate-carboxylase activity in both particulate and soluble fractions is very low in the 17-day foetal liver and increases to near adult levels before birth. 5. Phosphoenolpyruvate-carboxykinase activity in the soluble cell fraction increases 25-fold in the first 2 days after birth. This same enzyme in the mitochondria has considerable activity in the foetal and adult liver and is lower in the newborn. 6. Kinetic and other studies on the properties of phosphoenolpyruvate carboxykinase have shown no differences between the soluble and mitochondrial enzymes. 7. It is suggested that the appearance of the soluble phosphoenolpyruvate carboxykinase at birth initiates the rapid increase in overall gluconeogenesis at this stage. PMID:6049928

  16. Phosphoenolpyruvate:carbohydrate phosphotransferase systems of bacteria.

    PubMed Central

    Postma, P W; Lengeler, J W; Jacobson, G R

    1993-01-01

    Numerous gram-negative and gram-positive bacteria take up carbohydrates through the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS). This system transports and phosphorylates carbohydrates at the expense of PEP and is the subject of this review. The PTS consists of two general proteins, enzyme I and HPr, and a number of carbohydrate-specific enzymes, the enzymes II. PTS proteins are phosphoproteins in which the phospho group is attached to either a histidine residue or, in a number of cases, a cysteine residue. After phosphorylation of enzyme I by PEP, the phospho group is transferred to HPr. The enzymes II are required for the transport of the carbohydrates across the membrane and the transfer of the phospho group from phospho-HPr to the carbohydrates. Biochemical, structural, and molecular genetic studies have shown that the various enzymes II have the same basic structure. Each enzyme II consists of domains for specific functions, e.g., binding of the carbohydrate or phosphorylation. Each enzyme II complex can consist of one to four different polypeptides. The enzymes II can be placed into at least four classes on the basis of sequence similarity. The genetics of the PTS is complex, and the expression of PTS proteins is intricately regulated because of the central roles of these proteins in nutrient acquisition. In addition to classical induction-repression mechanisms involving repressor and activator proteins, other types of regulation, such as antitermination, have been observed in some PTSs. Apart from their role in carbohydrate transport, PTS proteins are involved in chemotaxis toward PTS carbohydrates. Furthermore, the IIAGlc protein, part of the glucose-specific PTS, is a central regulatory protein which in its nonphosphorylated form can bind to and inhibit several non-PTS uptake systems and thus prevent entry of inducers. In its phosphorylated form, P-IIAGlc is involved in the activation of adenylate cyclase and thus in the

  17. Activating phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase in combination for improvement of succinate production.

    PubMed

    Tan, Zaigao; Zhu, Xinna; Chen, Jing; Li, Qingyan; Zhang, Xueli

    2013-08-01

    Phosphoenolpyruvate (PEP) carboxylation is an important step in the production of succinate by Escherichia coli. Two enzymes, PEP carboxylase (PPC) and PEP carboxykinase (PCK), are responsible for PEP carboxylation. PPC has high substrate affinity and catalytic velocity but wastes the high energy of PEP. PCK has low substrate affinity and catalytic velocity but can conserve the high energy of PEP for ATP formation. In this work, the expression of both the ppc and pck genes was modulated, with multiple regulatory parts of different strengths, in order to investigate the relationship between PPC or PCK activity and succinate production. There was a positive correlation between PCK activity and succinate production. In contrast, there was a positive correlation between PPC activity and succinate production only when PPC activity was within a certain range; excessive PPC activity decreased the rates of both cell growth and succinate formation. These two enzymes were also activated in combination in order to recruit the advantages of each for the improvement of succinate production. It was demonstrated that PPC and PCK had a synergistic effect in improving succinate production. PMID:23747698

  18. Phosphoenolpyruvate carboxylase intrinsically located in the chloroplast of rice plays a crucial role in ammonium assimilation

    PubMed Central

    Masumoto, Chisato; Miyazawa, Shin-Ichi; Ohkawa, Hiroshi; Fukuda, Takuya; Taniguchi, Yojiro; Murayama, Seiji; Kusano, Miyako; Saito, Kazuki; Fukayama, Hiroshi; Miyao, Mitsue

    2010-01-01

    Phosphoenolpyruvate carboxylase (PEPC) is a key enzyme of primary metabolism in bacteria, algae, and vascular plants, and is believed to be cytosolic. Here we show that rice (Oryza sativa L.) has a plant-type PEPC, Osppc4, that is targeted to the chloroplast. Osppc4 was expressed in all organs tested and showed high expression in the leaves. Its expression in the leaves was confined to mesophyll cells, and Osppc4 accounted for approximately one-third of total PEPC protein in the leaf blade. Recombinant Osppc4 was active in the PEPC reaction, showing Vmax comparable to cytosolic isozymes. Knockdown of Osppc4 expression by the RNAi technique resulted in stunting at the vegetative stage, which was much more marked when rice plants were grown with ammonium than with nitrate as the nitrogen source. Comparison of leaf metabolomes of ammonium-grown plants suggested that the knockdown suppressed ammonium assimilation and subsequent amino acid synthesis by reducing levels of organic acids, which are carbon skeleton donors for these processes. We also identified the chloroplastic PEPC gene in other Oryza species, all of which are adapted to waterlogged soil where the major nitrogen source is ammonium. This suggests that, in addition to glycolysis, the genus Oryza has a unique route to provide organic acids for ammonium assimilation that involves a chloroplastic PEPC, and that this route is crucial for growth with ammonium. This work provides evidence for diversity of primary ammonium assimilation in the leaves of vascular plants. PMID:20194759

  19. The phosphoenolpyruvate/phosphate translocator is required for phenolic metabolism, palisade cell development, and plastid-dependent nuclear gene expression.

    PubMed Central

    Streatfield, S J; Weber, A; Kinsman, E A; Häusler, R E; Li, J; Post-Beittenmiller, D; Kaiser, W M; Pyke, K A; Flügge, U I; Chory, J

    1999-01-01

    The Arabidopsis chlorophyll a/b binding protein (CAB) gene underexpressed 1 (cue1) mutant underexpresses light-regulated nuclear genes encoding chloroplast-localized proteins. cue1 also exhibits mesophyll-specific chloroplast and cellular defects, resulting in reticulate leaves. Both the gene underexpression and the leaf cell morphology phenotypes are dependent on light intensity. In this study, we determine that CUE1 encodes the plastid inner envelope phosphoenolpyruvate/phosphate translocator (PPT) and define amino acid residues that are critical for translocator function. The biosynthesis of aromatics is compromised in cue1, and the reticulate phenotype can be rescued by feeding aromatic amino acids. Determining that CUE1 encodes PPT indicates the in vivo role of the translocator in metabolic partitioning and reveals a mesophyll cell-specific requirement for the translocator in Arabidopsis leaves. The nuclear gene expression defects in cue1 suggest that a light intensity-dependent interorganellar signal is modulated through metabolites dependent on a plastid supply of phosphoenolpyruvate. PMID:10488230

  20. Phosphoenolpyruvate Provision to Plastids Is Essential for Gametophyte and Sporophyte Development in Arabidopsis thaliana[C][W

    PubMed Central

    Prabhakar, Veena; Löttgert, Tanja; Geimer, Stefan; Dörmann, Peter; Krüger, Stephan; Vijayakumar, Vinod; Schreiber, Lukas; Göbel, Cornelia; Feussner, Kirstin; Feussner, Ivo; Marin, Kay; Staehr, Pia; Bell, Kirsten; Flügge, Ulf-Ingo; Häusler, Rainer E.

    2010-01-01

    Restriction of phosphoenolpyruvate (PEP) supply to plastids causes lethality of female and male gametophytes in Arabidopsis thaliana defective in both a phosphoenolpyruvate/phosphate translocator (PPT) of the inner envelope membrane and the plastid-localized enolase (ENO1) involved in glycolytic PEP provision. Homozygous double mutants of cue1 (defective in PPT1) and eno1 could not be obtained, and homozygous cue1 heterozygous eno1 mutants [cue1/eno1(+/−)] exhibited retarded vegetative growth, disturbed flower development, and up to 80% seed abortion. The phenotypes of diminished oil in seeds, reduced flavonoids and aromatic amino acids in flowers, compromised lignin biosynthesis in stems, and aberrant exine formation in pollen indicate that cue1/eno1(+/−) disrupts multiple pathways. While diminished fatty acid biosynthesis from PEP via plastidial pyruvate kinase appears to affect seed abortion, a restriction in the shikimate pathway affects formation of sporopollonin in the tapetum and lignin in the stem. Vegetative parts of cue1/eno1(+/−) contained increased free amino acids and jasmonic acid but had normal wax biosynthesis. ENO1 overexpression in cue1 rescued the leaf and root phenotypes, restored photosynthetic capacity, and improved seed yield and oil contents. In chloroplasts, ENO1 might be the only enzyme missing for a complete plastidic glycolysis. PMID:20798327

  1. Structural and functional studies of phosphoenolpyruvate carboxykinase from Mycobacterium tuberculosis.

    PubMed

    Machová, Iva; Snášel, Jan; Dostál, Jiří; Brynda, Jiří; Fanfrlík, Jindřich; Singh, Mahavir; Tarábek, Ján; Vaněk, Ondřej; Bednárová, Lucie; Pichová, Iva

    2015-01-01

    Tuberculosis, the second leading infectious disease killer after HIV, remains a top public health priority. The causative agent of tuberculosis, Mycobacterium tuberculosis (Mtb), which can cause both acute and clinically latent infections, reprograms metabolism in response to the host niche. Phosphoenolpyruvate carboxykinase (Pck) is the enzyme at the center of the phosphoenolpyruvate-pyruvate-oxaloacetate node, which is involved in regulating the carbon flow distribution to catabolism, anabolism, or respiration in different states of Mtb infection. Under standard growth conditions, Mtb Pck is associated with gluconeogenesis and catalyzes the metal-dependent formation of phosphoenolpyruvate. In non-replicating Mtb, Pck can catalyze anaplerotic biosynthesis of oxaloacetate. Here, we present insights into the regulation of Mtb Pck activity by divalent cations. Through analysis of the X-ray structure of Pck-GDP and Pck-GDP-Mn2+ complexes, mutational analysis of the GDP binding site, and quantum mechanical (QM)-based analysis, we explored the structural determinants of efficient Mtb Pck catalysis. We demonstrate that Mtb Pck requires presence of Mn2+ and Mg2+ cations for efficient catalysis of gluconeogenic and anaplerotic reactions. The anaplerotic reaction, which preferably functions in reducing conditions that are characteristic for slowed or stopped Mtb replication, is also effectively activated by Fe2+ in the presence of Mn2+ or Mg2+ cations. In contrast, simultaneous presence of Fe2+ and Mn2+ or Mg2+ inhibits the gluconeogenic reaction. These results suggest that inorganic ions can contribute to regulation of central carbon metabolism by influencing the activity of Pck. Furthermore, the X-ray structure determination, biochemical characterization, and QM analysis of Pck mutants confirmed the important role of the Phe triad for proper binding of the GDP-Mn2+ complex in the nucleotide binding site and efficient catalysis of the anaplerotic reaction. PMID:25798914

  2. Structural and Functional Studies of Phosphoenolpyruvate Carboxykinase from Mycobacterium tuberculosis

    PubMed Central

    Machová, Iva; Snášel, Jan; Dostál, Jiří; Brynda, Jiří; Fanfrlík, Jindřich; Singh, Mahavir; Tarábek, Ján; Vaněk, Ondřej; Bednárová, Lucie; Pichová, Iva

    2015-01-01

    Tuberculosis, the second leading infectious disease killer after HIV, remains a top public health priority. The causative agent of tuberculosis, Mycobacterium tuberculosis (Mtb), which can cause both acute and clinically latent infections, reprograms metabolism in response to the host niche. Phosphoenolpyruvate carboxykinase (Pck) is the enzyme at the center of the phosphoenolpyruvate-pyruvate-oxaloacetate node, which is involved in regulating the carbon flow distribution to catabolism, anabolism, or respiration in different states of Mtb infection. Under standard growth conditions, Mtb Pck is associated with gluconeogenesis and catalyzes the metal-dependent formation of phosphoenolpyruvate. In non-replicating Mtb, Pck can catalyze anaplerotic biosynthesis of oxaloacetate. Here, we present insights into the regulation of Mtb Pck activity by divalent cations. Through analysis of the X-ray structure of Pck-GDP and Pck-GDP-Mn2+ complexes, mutational analysis of the GDP binding site, and quantum mechanical (QM)-based analysis, we explored the structural determinants of efficient Mtb Pck catalysis. We demonstrate that Mtb Pck requires presence of Mn2+ and Mg2+ cations for efficient catalysis of gluconeogenic and anaplerotic reactions. The anaplerotic reaction, which preferably functions in reducing conditions that are characteristic for slowed or stopped Mtb replication, is also effectively activated by Fe2+ in the presence of Mn2+ or Mg2+ cations. In contrast, simultaneous presence of Fe2+ and Mn2+ or Mg2+ inhibits the gluconeogenic reaction. These results suggest that inorganic ions can contribute to regulation of central carbon metabolism by influencing the activity of Pck. Furthermore, the X-ray structure determination, biochemical characterization, and QM analysis of Pck mutants confirmed the important role of the Phe triad for proper binding of the GDP-Mn2+ complex in the nucleotide binding site and efficient catalysis of the anaplerotic reaction. PMID:25798914

  3. Regulation of Phosphoenolpyruvate Carboxylase and Crassulacean Acid Metabolism Induction in Mesembryanthemum crystallinum L. by Cytokinin 1

    PubMed Central

    Schmitt, Jürgen M.; Piepenbrock, Mechtild

    1992-01-01

    Phosphoenolpyruvate carboxylase (PEPCase), the key enzyme of Crassulacean acid metabolism, is induced by water stress in leaves of Mesembryanthemum crystallinum. In water-stressed plants or excised leaves, exogenous cytokinin suppresses PEPCase transcript accumulation in the leaves. Cytokinin (6-benzylaminopurine) used in concentrations from 5 to 500 micromolar (a) inhibits the upregulation of PEPCase transcripts, enzyme activity, and Crassulacean acid metabolism induction in salt-stressed intact plants when sprayed once daily during the stress period, (b) inhibits the accumulation of PEPCase mRNA in leaves from well-watered plants, (c) down-regulates PEPCase transcripts within 8 hours in prestressed, intact plants after a single spraying of an individual leaf, (d) inhibits accumulation of PEPCase transcripts in excised, wilting leaves, and (e) accelerates the net decrease of PEPCase transcripts in excised leaves from prestressed plants under rehydration conditions. When roots, the main site of cytokinin biosynthesis, are excised, PEPCase induction under drought stress is intensified. We propose that roots, acting as sensors of soil water status, may regulate PEPCase gene expression in the leaves with cytokinin as a signal transducer. ImagesFigure 2Figure 7 PMID:16669088

  4. Transcriptional activation of phosphoenolpyruvate carboxylase by phosphorus deficiency in tobacco.

    PubMed

    Toyota, Kentaro; Koizumi, Nozomu; Sato, Fumihiko

    2003-03-01

    Phosphoenolpyruvate carboxylase (PEPC), which catalyses the carboxylation of phosphoenolpyruvate using HCO(3)(-) to generate oxaloacetic acid, is an important enzyme in the primary metabolism of plants. Although the PEPC genes (ppc) comprise only a small gene family, the function of each gene is not clear, except for roles in C(4) photosynthesis and CAM. Three PEPC genes (Nsppc1-3) from the C(3) plant Nicotiana sylvestris were used to investigate their roles and regulation in a C(3) plant, and their regulation by phosphorus depletion in particular. First, the induction of PEPC by phosphorus depletion was confirmed. Next, Nsppc1 was determined to be mainly responsive to phosphorus deficiency at the transcriptional level. Further studies using transgenic tobacco harbouring a chimeric gene consisting of the 2.0 kb promoter region of Nsppc1 and the beta-glucuronidase (GUS) reporter showed that PEPC is transcriptionally induced. It was also found that sucrose had a synergistic effect on the induction of PEPC by phosphorus deficiency. A series of transgenic tobacco containing 5'-deletion mutants of Nsppc1 promoter::GUS fusion revealed that the -539 to -442 bp Nsppc1 promoter region, relative to the translation start site, was necessary for the response to phosphorus deficiency. Gain-of-function analysis using a construct containing three tandem repeats of the -539 to -442 bp region confirmed that this region was sufficient to induce the phosphorus-deficiency response in tobacco. PMID:12598567

  5. Phosphoenolpyruvate carboxykinase of kidney. Subcellular distribution and response to acid–base changes

    PubMed Central

    Flores, H.; Alleyne, G. A. O.

    1971-01-01

    1. A method for the assay of phosphoenolpyruvate carboxykinase is presented, based on the enzymic determination of the phosphoenolpyruvate produced by the enzyme reaction. 2. The subcellular distribution of phosphoenolpyruvate carboxykinase in the kidney of several animal species resembled the distribution in the liver. 3. The rise in enzyme activity in the kidney cortex of rats made acidotic by feeding with ammonium chloride was not prevented by administration of ethionine or actinomycin. 4. The possibility is suggested that in the kidney acidosis causes activation of an inactive form of the enzyme already present. PMID:5128664

  6. Metabolite Regulation of Partially Purified Soybean Nodule Phosphoenolpyruvate Carboxylase 1

    PubMed Central

    Schuller, Kathryn A.; Turpin, David H.; Plaxton, William C.

    1990-01-01

    Phosphoenolpyruvate carboxylase (PEPC) was purified 40-fold from soybean (Glycine max L. Merr.) nodules to a specific activity of 5.2 units per milligram per protein and an estimated purity of 28%. Native and subunit molecular masses were determined to be 440 and 100 kilodaltons, respectively, indicating that the enzyme is a homotetramer. The response of enzyme activity to phosphoenolpyruvate (PEP) concentration and to various effectors was influenced by assay pH and glycerol addition to the assay. At pH 7 in the absence of glycerol, the Km (PEP) was about twofold greater than at pH 7 in the presence of glycerol or at pH 8. At pH 7 or pH 8 the Km (MgPEP) was found to be significantly lower than the respective Km (PEP) values. Glucose-6-phosphate, fructose-6-phosphate, glucose-1-phosphate, and dihydroxyacetone phosphate activated PEPC at pH 7 in the absence of glycerol, but had no effect under the other assay conditions. Malate, aspartate, glutamate, citrate, and 2-oxoglutarate were potent inhibitors of PEPC at pH 7 in the absence of glycerol, but their effectiveness was decreased by raising the pH to 8 and/or by adding glycerol. In contrast, 3-phosphoglycerate and 2-phosphoglycerate were less effective inhibitors at pH 7 in the absence of glycerol than under the other assay conditions. Inorganic phosphate (up to 20 millimolar) was an activator at pH 7 in the absence of glycerol but an inhibitor under the other assay conditions. The possible significance of metabolite regulation of PEPC is discussed in relation to the proposed functions of this enzyme in legume nodule metabolism. Images Figure 1 Figure 2 PMID:16667849

  7. Analysis and elucidation of phosphoenolpyruvate carboxylase in cyanobacteria.

    PubMed

    Shylajanaciyar, Mohandass; Dineshbabu, Gnanasekaran; Rajalakshmi, Ramamoorthy; Subramanian, Gopalakrishnan; Prabaharan, Dharmar; Uma, Lakshmanan

    2015-02-01

    Phosphoenolpyruvate carboxylase (PEPC) a cytosolic enzyme of higher plants is also found in bacteria and cyanobacteria. Genetic and biochemical investigations have indicated that there are several isoforms of PEPC belonging to C3; C3/C4 and C4 groups but, the evolution of PEPC in cyanobacteria is not yet understood. The present study opens up an opportunity to understand the isoforms and functions of PEPC in cyanobacteria. The variations observed in PEPC among lower and higher orders of cyanobacteria, suggests convergent evolution of PEPC. There is a specific PEPC phosphorylation residue 'serine' at the N-terminus and PEPC determinant residue 'serine' at the C-terminal that facilitates high affinity for substrate binding. These residues were unique to higher orders of cyanobacteria, but, not in lower orders and other prokaryotes. The different PEPC forms of cyanobacteria were investigated for their kinetic properties with phosphoenolpyruvate as the substrate and the findings corroborated well with the in silico findings. In vitro enzymatic study of cyanobacteria belonging to three different orders demonstrated the role of aspartate as an allosteric effector, which inhibited PEPC by interacting with the highly conserved residues in the active site. The differences in mode of inhibition among the different order, thus, give a fair picture about the cyanobacterial PEPCs. The higher orders appear to possess the sequence coordinates and functionally conserved residues similar to isoforms of C4 type higher plants, whereas isoforms of PEPC of the lower orders did not resemble either that of C3 or C4 plants. PMID:25586080

  8. Temperature Responses of C4 Photosynthesis: Biochemical Analysis of Rubisco, Phosphoenolpyruvate Carboxylase, and Carbonic Anhydrase in Setaria viridis1[OPEN

    PubMed Central

    Boyd, Ryan A.; Gandin, Anthony; Cousins, Asaph B.

    2015-01-01

    The photosynthetic assimilation of CO2 in C4 plants is potentially limited by the enzymatic rates of Rubisco, phosphoenolpyruvate carboxylase (PEPc), and carbonic anhydrase (CA). Therefore, the activity and kinetic properties of these enzymes are needed to accurately parameterize C4 biochemical models of leaf CO2 exchange in response to changes in CO2 availability and temperature. There are currently no published temperature responses of both Rubisco carboxylation and oxygenation kinetics from a C4 plant, nor are there known measurements of the temperature dependency of the PEPc Michaelis-Menten constant for its substrate HCO3−, and there is little information on the temperature response of plant CA activity. Here, we used membrane inlet mass spectrometry to measure the temperature responses of Rubisco carboxylation and oxygenation kinetics, PEPc carboxylation kinetics, and the activity and first-order rate constant for the CA hydration reaction from 10°C to 40°C using crude leaf extracts from the C4 plant Setaria viridis. The temperature dependencies of Rubisco, PEPc, and CA kinetic parameters are provided. These findings describe a new method for the investigation of PEPc kinetics, suggest an HCO3− limitation imposed by CA, and show similarities between the Rubisco temperature responses of previously measured C3 species and the C4 plant S. viridis. PMID:26373659

  9. In Vivo and in Vitro Phosphorylation of the Phosphoenolpyruvate Carboxylase from Wheat Seeds during Germination.

    PubMed Central

    Osuna, L.; Gonzalez, M. C.; Cejudo, F. J.; Vidal, J.; Echevarria, C.

    1996-01-01

    Phosphoenolpyruvate carboxylase (PEPC) activity was detected in the aleurone endosperm of wheat (Triticum aestivum cv Chinese Spring) seeds, and specific anti-Sorghum C4 PEPC polyclonal anti-bodies cross-reacted with 103- and 100-kD polypeptides present in dry seeds and seeds that had imbibed; in addition, a new, 108-kD polypeptide was detected 6 h after imbibition. The use of specific anti-phosphorylation-site immunoglobulin G (APS-IgG) identified the presence of a phosphorylation motif equivalent to that found in other plant PEPCs studied so far. The binding of this APS-IgG to the target protein promoted changes in the properties of seed PEPC similar to those produced by phosphorylation, as previously shown for the recombinant Sorghum leaf C4 PEPC. In desalted seed extracts, an endogenous PEPC kinase activity catalyzed a bona fide phosphorylation of the target protein, as deduced from the immunoinhibition of the in vitro phosphorylation reaction by the APS- IgG. In addition, the major, 103-kD PEPC polypeptide was also shown to be radiolabeled in situ 48 h after imbibition in [32P]orthophosphate. The ratio between optimal (pH 8) and suboptimal (pH 7.3 or 7.1) PEPC activity decreased during germination, thereby suggesting a change in catalytic rate related to an in vivo phosphorylation process. These collective data document that the components needed for the regulatory phosphorylation of PEPC are present and functional during germination of wheat seeds. PMID:12226309

  10. The role of phosphoenolpyruvate carboxylase during C4 photosynthetic isotope exchange and stomatal conductance.

    PubMed

    Cousins, Asaph B; Baroli, Irene; Badger, Murray R; Ivakov, Alexander; Lea, Peter J; Leegood, Richard C; von Caemmerer, Susanne

    2007-11-01

    Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) plays a key role during C(4) photosynthesis and is involved in anaplerotic metabolism, pH regulation, and stomatal opening. Heterozygous (Pp) and homozygous (pp) forms of a PEPC-deficient mutant of the C(4) dicot Amaranthus edulis were used to study the effect of reduced PEPC activity on CO(2) assimilation rates, stomatal conductance, and (13)CO(2) (Delta(13)C) and C(18)OO (Delta(18)O) isotope discrimination during leaf gas exchange. PEPC activity was reduced to 42% and 3% and the rates of CO(2) assimilation in air dropped to 78% and 10% of the wild-type values in the Pp and pp mutants, respectively. Stomatal conductance in air (531 mubar CO(2)) was similar in the wild-type and Pp mutant but the pp mutant had only 41% of the wild-type steady-state conductance under white light and the stomata opened more slowly in response to increased light or reduced CO(2) partial pressure, suggesting that the C(4) PEPC isoform plays an essential role in stomatal opening. There was little difference in Delta(13)C between the Pp mutant (3.0 per thousand +/- 0.4 per thousand) and wild type (3.3 per thousand +/- 0.4 per thousand), indicating that leakiness (), the ratio of CO(2) leak rate out of the bundle sheath to the rate of CO(2) supply by the C(4) cycle, a measure of the coordination of C(4) photosynthesis, was not affected by a 60% reduction in PEPC activity. In the pp mutant Delta(13)C was 16 per thousand +/- 3.2 per thousand, indicative of direct CO(2) fixation by Rubisco in the bundle sheath at ambient CO(2) partial pressure. Delta(18)O measurements indicated that the extent of isotopic equilibrium between leaf water and the CO(2) at the site of oxygen exchange () was low (0.6) in the wild-type and Pp mutant but increased to 0.9 in the pp mutant. We conclude that in vitro carbonic anhydrase activity overestimated as compared to values determined from Delta(18)O in wild-type plants. PMID:17827274

  11. Molecular characteristics of phosphoenolpyruvate: mannose phosphotransferase system in Streptococcus bovis.

    PubMed

    Asanuma, Narito; Yoshii, Takahiro; Hino, Tsuneo

    2004-07-01

    To elucidate the regulatory mechanism of catabolite control in Streptococcus bovis, we investigated the molecular properties and gene expression of the mannose-specific phosphoenolpyruvate (PEP)-dependent sugar: phosphotransferase system (PTS). The mannose PTS gene cluster (man) was found to comprise a gene encoding enzyme (E) II AB (manL) and genes encoding EIIC (manM), EIID (manN), and a putative regulator (manO). The gene cluster (man operon) was transcribed from one transcriptional start site, which was located 40 bp upstream of the manL start codon. However, two transcriptional start sites were found between manN and manO in primer extension analysis, and the manO may be transcribed independently from the man operon. The man operon and manO were constitutively transcribed without being affected by culture conditions, such as the sugar supplied (glucose, galactose, fructose, maltose, lactose, sucrose, or mannose), growth rate, or pH. PMID:15297922

  12. Experimental evidence of phosphoenolpyruvate resynthesis from pyruvate in illuminated leaves.

    PubMed

    Tcherkez, Guillaume; Mahé, Aline; Boex-Fontvieille, Edouard; Gout, Elisabeth; Guérard, Florence; Bligny, Richard

    2011-09-01

    Day respiration is the cornerstone of nitrogen assimilation since it provides carbon skeletons to primary metabolism for glutamate (Glu) and glutamine synthesis. However, recent studies have suggested that the tricarboxylic acid pathway is rate limiting and mitochondrial pyruvate dehydrogenation is partly inhibited in the light. Pyruvate may serve as a carbon source for amino acid (e.g. alanine) or fatty acid synthesis, but pyruvate metabolism is not well documented, and neither is the possible resynthesis of phosphoenolpyruvate (PEP). Here, we examined the capacity of pyruvate to convert back to PEP using (13)C and (2)H labeling in illuminated cocklebur (Xanthium strumarium) leaves. We show that the intramolecular labeling pattern in Glu, 2-oxoglutarate, and malate after (13)C-3-pyruvate feeding was consistent with (13)C redistribution from PEP via the PEP-carboxylase reaction. Furthermore, the deuterium loss in Glu after (2)H(3)-(13)C-3-pyruvate feeding suggests that conversion to PEP and back to pyruvate washed out (2)H atoms to the solvent. Our results demonstrate that in cocklebur leaves, PEP resynthesis occurred as a flux from pyruvate, approximately 0.5‰ of the net CO(2) assimilation rate. This is likely to involve pyruvate inorganic phosphate dikinase and the fundamental importance of this flux for PEP and inorganic phosphate homeostasis is discussed. PMID:21730197

  13. Phosphoenolpyruvate-dependent protein kinase from skeletal muscle

    SciTech Connect

    Khandelwal, R.L.; Bhanot, P.; Waygood, E.B.

    1986-05-01

    Soluble extracts of skeletal muscle from rat, rabbit and hamster when incubated with 0.1 mM (/sup 32/P)phosphoenolpyruvate give rise to a similar set of phosphoproteins as resolved by SDS-PAGE with Mr 25,000, 35,000, 37,000, 43,000 and 59,000. The phosphorylation of these proteins is neither inhibited by excess ATP nor achieved by incubation with (..gamma..-/sup 32/P)ATP. Except for the Mr 43,000 phosphoprotein, the phosphorylation of the other proteins dramatically increased in the presence of 0.1 mM CTP. Although phosphatase inhibits such as NaF and PPi were not effective, CTP may act to inhibit phosphatase activity rather than activating a protein kinase. The phosphoamino acids produced in these phosphoproteins were acid stable and only phosphoserine has been routinely identified. Using DEAE-cellulose, CM-Sephadex and Ultrogel AcA44 chromatography, the Mr 37,000 phosphoprotein has been purified from rabbit skeletal muscle to near homogeneity. No physiological role for either the protein kinase or its substrates has yet been found.

  14. Exploring biochemical and functional features of Leishmania major phosphoenolpyruvate carboxykinase.

    PubMed

    Sosa, Máximo Hernán; Giordana, Lucila; Nowicki, Cristina

    2015-10-01

    This work reports the first functional characterization of leishmanial PEPCK. The recombinant Leishmania major enzyme (Lmj_PEPCK) exhibits equivalent kcat values for the phosphoenolpyruvate (PEP) and oxaloacetate (OAA) forming reactions. The apparent Km towards OAA is 10-fold lower than that for PEP, while the Km values for ADP and ATP are equivalent. Mutagenesis studies showed that D241, D242 and H205 of Lmj_PEPCK like the homologous residues of all known PEPCKs are implicated in metal ions binding. In contrast, the replacement of R43 for Q nearly abolishes Lmj_PEPCK activity. Moreover, the Y180F variant exhibits unchanged Km values for PEP, Mn(2+), and [Formula: see text] , being the kcat for PEP- but not that for OAA-forming reaction more notably decreased. Instead, the Y180A mutant displays an increase in the Km value towards Mn(2+). Therefore in Lmj_PEPCK, Y180 seems to exert different functions to those of the analogous residue in ATP- and GTP-dependant enzymes. Besides, the guanidinium group of R43 appears to play an essential but yet unknown role. These findings promote the need for further structural studies to disclose whether Y180 and R43 participate in the catalytic mechanism or/and in the transitions between the open and the catalytically competent (closed) forms of Lmj_PEPCK. PMID:26271440

  15. Propionate induces the bovine cytosolic phosphoenolpyruvate carboxykinase promoter activity.

    PubMed

    Zhang, Qian; Koser, Stephanie L; Donkin, Shawn S

    2016-08-01

    Cytosolic phosphoenolpyruvate carboxykinase (PCK1) is a critical enzyme within the metabolic networks for gluconeogenesis, hepatic energy metabolism, and tricarboxylic acid cycle function, and is controlled by several transcription factors including hepatic nuclear factor 4α (HNF4α). The primary objective of the present study was to determine whether propionate regulates bovine PCK1 transcription. The second objective was to determine the action of cyclic AMP (cAMP), glucocorticoids, and insulin, hormonal cues known to modulate glucose metabolism, on bovine PCK1 transcriptional activity. The proximal promoter of the bovine PCK1 gene was ligated to a Firefly luciferase reporter and transfected into H4IIE hepatoma cells. Cells were exposed to treatments for 23 h and luciferase activity was determined in cell lysates. Activity of the PCK1 promoter was linearly induced by propionate, and maximally increased 7-fold with 2.5 mM propionate, which was not muted by 100 nM insulin. Activity of the PCK1 promoter was increased 1-fold by either 1.0 mM cAMP or 5.0µM dexamethasone, and 2.2-fold by their combination. Induction by cAMP and dexamethasone was repressed 50% by 100 nM insulin. Propionate, cAMP, and dexamethasone acted synergistically to induce the PCK1 promoter activity. Propionate-responsive regions, identified by 5' deletion analysis, were located between -1,238 and -409 bp and between -85 and +221 bp. Deletions of the core sequences of the 2 putative HNF4α sites decreased the responsiveness to propionate by approximately 40%. These data indicate that propionate regulates its own metabolism through transcriptional stimulation of the bovine PCK1 gene. This induction is mediated, in part, by the 2 putative HNF4α binding sites in the bovine PCK1 promoter. PMID:27289145

  16. Phosphoenolpyruvate carboxylase from pennywort (Umbilicus rupestris). Changes in properties after exposure to water stress.

    PubMed Central

    Daniel, P P; Bryant, J A; Woodward, F I

    1984-01-01

    Umbilicus rupestris (pennywort) switches from C3 photosynthesis to an incomplete form of crassulacean acid metabolism (referred to as 'CAM-idling') when exposed to water stress (drought). This switch is accompanied by an increase in the activity of phosphoenolpyruvate carboxylase. This enzyme also shows several changes in properties, including a marked decrease in sensitivity to acid pH, a lower Km for phosphoenolpyruvate, very much decreased sensitivity to the allosteric inhibitor malate, and increased responsiveness to the allosteric effector glucose 6-phosphate. The Mr of the enzyme remains unchanged, at approx. 185 000. These changes in properties of phosphoenolpyruvate carboxylase are discussed in relation to the roles of the enzyme in C3 and in CAM plants. Images Fig. 5. PMID:6712622

  17. Multiple isoforms of phosphoenolpyruvate carboxylase in the Orchidaceae (subtribe Oncidiinae): implications for the evolution of crassulacean acid metabolism

    PubMed Central

    Silvera, Katia; Winter, Klaus; Rodriguez, B. Leticia; Albion, Rebecca L.; Cushman, John C.

    2014-01-01

    Phosphoenolpyruvate carboxylase (PEPC) catalyses the initial fixation of atmospheric CO2 into oxaloacetate and subsequently malate. Nocturnal accumulation of malic acid within the vacuole of photosynthetic cells is a typical feature of plants that perform crassulacean acid metabolism (CAM). PEPC is a ubiquitous plant enzyme encoded by a small gene family, and each member encodes an isoform with specialized function. CAM-specific PEPC isoforms probably evolved from ancestral non-photosynthetic isoforms by gene duplication events and subsequent acquisition of transcriptional control elements that mediate increased leaf-specific or photosynthetic-tissue-specific mRNA expression. To understand the patterns of functional diversification related to the expression of CAM, ppc gene families and photosynthetic patterns were characterized in 11 closely related orchid species from the subtribe Oncidiinae with a range of photosynthetic pathways from C3 photosynthesis (Oncidium cheirophorum, Oncidium maduroi, Rossioglossum krameri, and Oncidium sotoanum) to weak CAM (Oncidium panamense, Oncidium sphacelatum, Gomesa flexuosa and Rossioglossum insleayi) and strong CAM (Rossioglossum ampliatum, Trichocentrum nanum, and Trichocentrum carthagenense). Phylogenetic analysis revealed the existence of two main ppc lineages in flowering plants, two main ppc lineages within the eudicots, and three ppc lineages within the Orchidaceae. Our results indicate that ppc gene family expansion within the Orchidaceae is likely to be the result of gene duplication events followed by adaptive sequence divergence. CAM-associated PEPC isoforms in the Orchidaceae probably evolved from several independent origins. PMID:24913627

  18. Evidence for Light-stimulated Synthesis of Phosphoenolpyruvate Carboxylase in Leaves of Maize 1

    PubMed Central

    Hague, Donald R.; Sims, Thomas L.

    1980-01-01

    Illumination (22,000 lumens per meter2) of etiolated maize plants for 80 hours brings about a 5-fold increase in phosphoenolpyruvate carboxylase activity per unit of protein. An increase in carboxylase protein and incorporation of [35S]methionine into the protein occurs simultaneously with the activity increase. In green plants, the level of phosphoenolpyruvate carboxylase protein and enzyme activity is dependent on the intensity of light during growth. These results are consistent with the conclusion that the activity increase results from light-stimulated de novo synthesis of phosphoenolypyruvate carboxylase protein. Images PMID:16661464

  19. Purification and characterization of a novel phosphoenolpyruvate carboxylase from banana fruit.

    PubMed Central

    Law, R D; Plaxton, W C

    1995-01-01

    Phosphoenolpyruvate carboxylase (PEPC) from ripened banana (Musa cavendishii L.) fruits has been purified 127-fold to apparent homogeneity and a final specific activity of 32 mumol of oxaloacetate produced/min per mg of protein. Non-denaturing PAGE of the final preparation resolved a single protein-staining band that co-migrated with PEPC activity. Polypeptides of 103 (alpha-subunit) and 100 (beta-subunit) kDa, which stain for protein with equal intensity and cross-react strongly with anti-(maize leaf PEPC) immune serum, were observed following SDS/PAGE of the final preparation. CNBr cleavage patterns of the two subunits were similar, but not identical, suggesting that these polypeptides are related, but distinct, proteins. The enzyme's native molecular mass was estimated to be about 425 kDa. These data indicate that in contrast to the homotetrameric PEPC from most other sources, the banana fruit enzyme exists as an alpha 2 beta 2 heterotetramer. Monospecific rabbit anti-(banana PEPC) immune serum effectively immunoprecipitated the activity of the purified enzyme. Immunoblotting studies established that the 100 kDa subunit did not arise via proteolysis of the 103 kDa subunit after tissue extraction, and that the subunit composition of banana PEPC remains uniform throughout the ripening process. PEPC displayed a typical pH activity profile with an alkaline optimum and activity rapidly decreasing below pH 7.0. Enzymic activity was absolutely dependent on the presence of a bivalent metal cation, with Mg2+ or Mn2+ fulfilling this requirement. The response of the PEPC activity to PEP concentration and to various effectors was greatly influenced by pH and glycerol addition to the assay. The enzyme was activated by hexose-monophosphates and potently inhibited by malate, succinate, aspartate and glutamate at pH 7.0, whereas the effect of these metabolites was considerably diminished or completely abolished at pH 8.0. The significance of metabolite regulation of PEPC is

  20. Carbon Dioxide Metabolism in Leaf Epidermal Tissue 1

    PubMed Central

    Willmer, C. M.; Pallas, J. E.; Black, C. C.

    1973-01-01

    A number of plant species were surveyed to obtain pure leaf epidermal tissue in quantity. Commelina communis L. and Tulipa gesnariana L. (tulip) were chosen for further work. Chlorophyll a/b ratios of epidermal tissues were 2.41 and 2.45 for C. communis and tulip, respectively. Phosphoenolpyruvate carboxylase, ribulose-1,5-diphosphate carboxylase, malic enzyme, and NAD+ and NADP+ malate dehydrogenases were assayed with epidermal tissue and leaf tissue minus epidermal tissue. In both species, there was less ribulose 1,5-diphosphate than phosphoenolpyruvate carboxylase activity in epidermal tissue whether expressed on a protein or chlorophyll basis whereas the reverse was true for leaf tissue minus epidermal tissue. In both species, malic enzyme activities were higher in epidermal tissue than in the remaining leaf tissue when expressed on a protein or chlorophyll basis. In both species, NAD+ and NADP+ malate dehydrogenase activities were higher in the epidermal tissue when expressed on a chlorophyll basis; however, on a protein basis, the converse was true. Microautoradiography of C. communis epidermis and histochemical tests for keto acids suggested that CO2 fixation occurred predominantly in the guard cells. The significance and possible location of the enzymes are discussed in relation to guard cell metabolism. Images PMID:16658581

  1. Leaf Development

    PubMed Central

    2013-01-01

    Leaves are the most important organs for plants. Without leaves, plants cannot capture light energy or synthesize organic compounds via photosynthesis. Without leaves, plants would be unable perceive diverse environmental conditions, particularly those relating to light quality/quantity. Without leaves, plants would not be able to flower because all floral organs are modified leaves. Arabidopsis thaliana is a good model system for analyzing mechanisms of eudicotyledonous, simple-leaf development. The first section of this review provides a brief history of studies on development in Arabidopsis leaves. This history largely coincides with a general history of advancement in understanding of the genetic mechanisms operating during simple-leaf development in angiosperms. In the second section, I outline events in Arabidopsis leaf development, with emphasis on genetic controls. Current knowledge of six important components in these developmental events is summarized in detail, followed by concluding remarks and perspectives. PMID:23864837

  2. Evolution of the C4 phosphoenolpyruvate carboxylase promoter of the C4 species Flaveria trinervia: the role of the proximal promoter region

    PubMed Central

    Engelmann, Sascha; Zogel, Corinna; Koczor, Maria; Schlue, Ute; Streubel, Monika; Westhoff, Peter

    2008-01-01

    Background The key enzymes of photosynthetic carbon assimilation in C4 plants have evolved independently several times from C3 isoforms that were present in the C3 ancestral species. The C4 isoform of phosphoenolpyruvate carboxylase (PEPC), the primary CO2-fixing enzyme of the C4 cycle, is specifically expressed at high levels in mesophyll cells of the leaves of C4 species. We are interested in understanding the molecular changes that are responsible for the evolution of this C4-characteristic PEPC expression pattern, and we are using the genus Flaveria (Asteraceae) as a model system. It is known that cis-regulatory sequences for mesophyll-specific expression of the ppcA1 gene of F. trinervia (C4) are located within a distal promoter region (DR). Results In this study we focus on the proximal region (PR) of the ppcA1 promoter of F. trinervia and present an analysis of its function in establishing a C4-specific expression pattern. We demonstrate that the PR harbours cis-regulatory determinants which account for high levels of PEPC expression in the leaf. Our results further suggest that an intron in the 5' untranslated leader region of the PR is not essential for the control of ppcA1 gene expression. Conclusion The allocation of cis-regulatory elements for enhanced expression levels to the proximal region of the ppcA1 promoter provides further insight into the regulation of PEPC expression in C4 leaves. PMID:18208593

  3. Salt stress leads to differential expression of two isogenes of phosphoenolpyruvate carboxylase during Crassulacean acid metabolism induction in the common ice plant.

    PubMed Central

    Cushman, J C; Meyer, G; Michalowski, C B; Schmitt, J M; Bohnert, H J

    1989-01-01

    The common ice plant is a facultative halophyte in which Crassulacean acid metabolism, a metabolic adaptation to arid environments, can be induced by irrigating plants with high levels of NaCl or by drought. This stress-induced metabolic transition is accompanied by up to a 50-fold increase in the activity of phosphoenolpyruvate carboxylase (PEPCase). To analyze the molecular basis of this plant response to water stress, we have isolated and characterized two members of the PEPCase gene family from the common ice plant. The PEPCase isogenes, designated Ppc1 and Ppc2, have conserved intron-exon organizations, are 76.4% identical at the nucleotide sequence level within exons, and encode predicted polypeptides with 83% amino acid identity. Steady-state levels of mRNAs from the two genes differ dramatically when plants are salt-stressed. Transcripts of Ppc1 increase about 30-fold in leaves within 5 days of salt stress. In contrast, steady-state levels of Ppc2 transcripts decrease slightly in leaf tissue over the same stress period. Steady-state levels of transcripts of both genes decrease in roots over 5 days of salt stress. We have used in vitro transcription assays with nuclei isolated from leaves to demonstrate that the increased expression of Ppc1 caused by water stress occurs in part at the transcriptional level. PMID:2535520

  4. Discovery of PPi-type Phosphoenolpyruvate Carboxykinase Genes in Eukaryotes and Bacteria.

    PubMed

    Chiba, Yoko; Kamikawa, Ryoma; Nakada-Tsukui, Kumiko; Saito-Nakano, Yumiko; Nozaki, Tomoyoshi

    2015-09-25

    Phosphoenolpyruvate carboxykinase (PEPCK) is one of the pivotal enzymes that regulates the carbon flow of the central metabolism by fixing CO2 to phosphoenolpyruvate (PEP) to produce oxaloacetate or vice versa. Whereas ATP- and GTP-type PEPCKs have been well studied, and their protein identities are established, inorganic pyrophosphate (PPi)-type PEPCK (PPi-PEPCK) is poorly characterized. Despite extensive enzymological studies, its protein identity and encoding gene remain unknown. In this study, PPi-PEPCK has been identified for the first time from a eukaryotic human parasite, Entamoeba histolytica, by conventional purification and mass spectrometric identification of the native enzyme, followed by demonstration of its enzymatic activity. A homolog of the amebic PPi-PEPCK from an anaerobic bacterium Propionibacterium freudenreichii subsp. shermanii also exhibited PPi-PEPCK activity. The primary structure of PPi-PEPCK has no similarity to the functional homologs ATP/GTP-PEPCKs and PEP carboxylase, strongly suggesting that PPi-PEPCK arose independently from the other functional homologues and very likely has unique catalytic sites. PPi-PEPCK homologs were found in a variety of bacteria and some eukaryotes but not in archaea. The molecular identification of this long forgotten enzyme shows us the diversity and functional redundancy of enzymes involved in the central metabolism and can help us to understand the central metabolism more deeply. PMID:26269598

  5. Carbon dioxide metabolism by Capnocytophaga ochracea: identification, characterization, and regulation of a phosphoenolpyruvate carboxykinase.

    PubMed Central

    Kapke, P A; Brown, A T; Lillich, T T

    1980-01-01

    Cell suspensions of Capnocytophaga ochracea incorporated [14C]NaHCO3 into a major four-carbon fermentation product, succinate, and cell-free extracts from this organism contained high levels of phosphoenolpyruvate carboxykinase (PEPCK). PEPCK is the major, if not the only, CO2(HCO-3)-fixing enzyme in C. ochracea since cell-free extracts were devoid of pyruvate-dependent and other phosphoenolpyruvate (PEP)-dependent CO2(HCO-3)-fixing enzymes. The reaction products of the enzyme, which was partially purified by diethylaminoethylcellulose column chromatography, were identified as adenosine 5'-triphosphate (ATP) and oxalacetate. The enzyme showed maximum activity when manganese (Mn2+) was the divalent cation in the incubation mixture, and it had an absolute requirement for the nucleoside 5-'diphosphate adenosine 5'-diphosphate (ADP). PEPCK showed a sigmoidal kinetic response to the Mn2+ concentration and homotropic interactions in its kinetic responses to each of its three substrates PEP, ADP, and CO2(HCO-3). The (S)0.5v values for Mn2+, PEP, ADP, and CO2(CHO-3) were approximately 0.08, 0.3, 0.1, and 10 mM, respectively, and Hill coefficients for these same ligands were 2.60, 1.7, 1.9, and 3.0, respectively. In addition, C. ochracea PEPCK is under metabolic control by the nucleoside -5'-triphosphate ATP, and it also showed a sigmoidal kinetic response to this allosteric effector. The Hill coefficient for ATP was 2.70. PMID:6769807

  6. Regulation of Phosphoenolpyruvate Carboxylase from the Green Alga Selenastrum minutum1

    PubMed Central

    Schuller, Kathryn A.; Plaxton, William C.; Turpin, David H.

    1990-01-01

    Two isoforms of phosphoenolpyruvate carboxylase (PEPC) with very different regulatory properties were partially purified from the green alga Selenastrum minutum. They were designated PEPC1 and PEPC2. PEPC1 showed sigmoidal kinetics with respect to phosphoenolpyruvate (PEP) whereas PEPC2 exhibited a typical Michaelis-Menten response. The S0.5(PEP) of PEPC1 was 2.23 millimolar. This was fourfold greater than the S0.5(PEP) of PEPC2, which was 0.57 millimolar. PEPC1 was activated more than fourfold by 2.0 millimolar glutamine and sixfold by 2.0 millimolar dihydroxyacetone phosphate (DHAP) at a subsaturating PEP concentration of 0.625 millimolar. In contrast, PEPC2 showed only 8% and 52% activation by glutamine and DHAP, respectively. The effects of glutamine and DHAP were additive. PEPC1 was more sensitive to inhibition by glutamate, 2-oxoglutarate, and aspartate than PEPC2. Both isoforms were equally inhibited by malate. All of these metabolites affected only the S0.5(PEP) not the Vmax. The regulatory properties of S. minutum PEPC in vitro are discussed in terms of (a) increased rates of dark carbon fixation (shown to be catalyzed predominantly by PEPC) and (b) changes in metabolite levels in vivo during enhanced NH4+ assimilation. Finally, a model is proposed for the regulation of PEPC in vivo in relation to its role in replenishing tricarboxylic acid cycle intermediates consumed in NH4+ assimilation. PMID:16667617

  7. Inhibition of Pig Phosphoenolpyruvate Carboxykinase Isoenzymes by 3-Mercaptopicolinic Acid and Novel Inhibitors.

    PubMed

    Hidalgo, Jorge; Latorre, Pedro; Carrodeguas, José Alberto; Velázquez-Campoy, Adrián; Sancho, Javier; López-Buesa, Pascual

    2016-01-01

    There exist two isoforms of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) in pig populations that differ in a single amino acid (Met139Leu). The isoenzymes have different kinetic properties, affecting more strongly the Km and Vmax of nucleotides. They are associated to different phenotypes modifying traits of considerable economic interest. In this work we use inhibitors of phosphoenolpyruvate carboxykinase activity to search for further differences between these isoenzymes. On the one hand we have used the well-known inhibitor 3-mercaptopicolinic acid. Its inhibition patterns were the same for both isoenzymes: a three-fold decrease of the Ki values for GTP in 139Met and 139Leu (273 and 873 μM, respectively). On the other hand, through screening of a chemical library we have found two novel compounds with inhibitory effects of a similar magnitude to that of 3-mercaptopicolinic acid but with less solubility and specificity. One of these novel compounds, (N'1-({5-[1-methyl-5-(trifluoromethyl)-1H-pyrazol-3-yl]-2-thienyl}methylidene)-2,4-dichlorobenzene-1-carbohydrazide), exhibited significantly different inhibitory effects on either isoenzyme: it enhanced threefold the apparent Km value for GTP in 139Met, whereas in 139Leu, it reduced it from 99 to 69 μM. The finding of those significant differences in the binding of GTP reinforces the hypothesis that the Met139Leu substitution affects strongly the nucleotide binding site of PEPCK-C. PMID:27391465

  8. Inhibition of Pig Phosphoenolpyruvate Carboxykinase Isoenzymes by 3-Mercaptopicolinic Acid and Novel Inhibitors

    PubMed Central

    Hidalgo, Jorge; Latorre, Pedro; Carrodeguas, José Alberto; Velázquez-Campoy, Adrián; Sancho, Javier; López-Buesa, Pascual

    2016-01-01

    There exist two isoforms of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) in pig populations that differ in a single amino acid (Met139Leu). The isoenzymes have different kinetic properties, affecting more strongly the Km and Vmax of nucleotides. They are associated to different phenotypes modifying traits of considerable economic interest. In this work we use inhibitors of phosphoenolpyruvate carboxykinase activity to search for further differences between these isoenzymes. On the one hand we have used the well-known inhibitor 3-mercaptopicolinic acid. Its inhibition patterns were the same for both isoenzymes: a three-fold decrease of the Ki values for GTP in 139Met and 139Leu (273 and 873 μM, respectively). On the other hand, through screening of a chemical library we have found two novel compounds with inhibitory effects of a similar magnitude to that of 3-mercaptopicolinic acid but with less solubility and specificity. One of these novel compounds, (N'1-({5-[1-methyl-5-(trifluoromethyl)-1H-pyrazol-3-yl]-2-thienyl}methylidene)-2,4-dichlorobenzene-1-carbohydrazide), exhibited significantly different inhibitory effects on either isoenzyme: it enhanced threefold the apparent Km value for GTP in 139Met, whereas in 139Leu, it reduced it from 99 to 69 μM. The finding of those significant differences in the binding of GTP reinforces the hypothesis that the Met139Leu substitution affects strongly the nucleotide binding site of PEPCK-C. PMID:27391465

  9. Partitioning of Nitrogen among Ribulose-1,5-bisphosphate Carboxylase/Oxygenase, Phosphoenolpyruvate Carboxylase, and Pyruvate Orthophosphate Dikinase as Related to Biomass Productivity in Maize Seedlings.

    PubMed

    Sugiyama, T; Mizuno, M; Hayashi, M

    1984-07-01

    Maize (Zea mays L. cv Golden Cross Bantam T51) seedlings were grown under full sunlight or 50% sunlight in a temperature-controlled glasshouse at the temperatures of near optimum (30/25 degrees C) and suboptimum (17/13 degrees C) with seven levels of nitrate-N (0.4 to 12 millimolars). The contents of phosphoenolpyruvate carboxylase (PEPC), pyruvate orthophosphate dikinase (PPD), and ribulose-1,5-P(2) carboxylase/oxygenase (RuBisCO) were immunochemically determined for each treatment with rabbit antibodies raised against the respective maize leaf proteins (anti-PEPC and anti-PPD) or spinach leaf protein (anti-RuBisCO). The content of each enzymic protein increased with increasing N and raised under reduced temperature. The positive effect of light intensity on their contents was evident only at near optimal temperature. The relative increase in PEPC and PPD content with increasing N was significantly greater than that of RuBisCO irrespective of growth conditions. These enzymic proteins comprised about 8, 6, and 35% of total soluble protein, respectively, at near optimal growth condition. In contrast to significant increase in the proportion of soluble protein allocated to PEPC and PPD seen under certain conditions, the proportion allocated to RuBisCO decreased reciprocally with an increased biomass yield by N supply.These results indicated that the levels of PEPC and PPD parallel to maize biomass more tightly than that of RuBisCO at least under near optimal growth condition. PMID:16663684

  10. Immunolocalization of carbonic anhydrase and phosphoenolpyruvate carboxylase in developing seeds of Medicago sativa.

    PubMed

    Aivalakis, Georgios; Dimou, Maria; Flemetakis, Emmanouil; Plati, Fotini; Katinakis, Panagiotis; Drossopoulos, J B

    2004-03-01

    To investigate the role of carbonic anhydrase (CA; EC 4.2.1.1) and phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) during Medicago sativa seed development, the distribution of both proteins was examined using an immunohistological approach. Both enzymes are co-localized in most ovular and embryonic tissues. In early stages of seed development, both proteins were abundant in embryo and integuments, while at subsequent stages both proteins are accumulated in endosperm, nucellus and integuments. At late stages of seed development when both endosperm and nucellus are degraded, significant accumulation of both proteins was observed in the embryo proper. Chlorophyll was found to accumulate in embryos after the heart stage and reached a maximum at mature stage. It is suggested that CA and PEPC play a role in respiratory carbon dioxide refixation while generating malate to support amino acid and/or fatty acids biosynthesis. PMID:15051041

  11. The phosphoenolpyruvate:sugar phosphotransferase system is involved in sensitivity to the glucosylated bacteriocin sublancin.

    PubMed

    Garcia De Gonzalo, C V; Denham, E L; Mars, R A T; Stülke, J; van der Donk, W A; van Dijl, J M

    2015-11-01

    The mode of action of a group of glycosylated antimicrobial peptides known as glycocins remains to be elucidated. In the current study of one glycocin, sublancin, we identified the phosphoenolpyruvate:sugar phosphotransferase system (PTS) of Bacillus species as a key player in bacterial sensitivity. Sublancin kills several Gram-positive bacteria, such as Bacillus species and Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). Unlike other classes of bacteriocins for which the PTS is involved in their mechanism of action, we show that the addition of PTS-requiring sugars leads to increased resistance rather than increased sensitivity, suggesting that sublancin has a distinct mechanism of action. Collectively, our present mutagenesis and genomic studies demonstrate that the histidine-containing phosphocarrier protein (HPr) and domain A of enzyme II (PtsG) in particular are critical determinants for bacterial sensitivity to sublancin. PMID:26282429

  12. Expression of Escherichia coli phosphoenolpyruvate carboxylase in a cyanobacterium. Functional complementation of Synechococcus PCC 7942 ppc.

    PubMed Central

    Luinenburg, I; Coleman, J R

    1993-01-01

    The gene (ppc) coding for phosphoenolpyruvate carboxylase (PEPCase) in the cyanobacterium Synechococcus PCC 7942 has been inactivated via insertional mutagenesis while being functionally complemented by Escherichia coli ppc. Cyanobacterial cells functionally complemented by E. coli ppc showed decreased PEPCase activity in crude cell lysates and detergent-permeabilized whole cell assays. Decreased rates of growth, reduced levels of chlorophyll a, and decreased photosynthetic O2 evolution capacity per cell when compared to wild-type cyanobacterial cells were also observed. Phycobiliprotein levels were not affected. The results are discussed in terms of the impact of reduced PEPCase activity on cyanobacterial cell metabolism and the regulatory properties of the E. coli gene product. PMID:8278492

  13. The Phosphoenolpyruvate:Sugar Phosphotransferase System Is Involved in Sensitivity to the Glucosylated Bacteriocin Sublancin

    PubMed Central

    Garcia De Gonzalo, C. V.; Denham, E. L.; Mars, R. A. T.; Stülke, J.

    2015-01-01

    The mode of action of a group of glycosylated antimicrobial peptides known as glycocins remains to be elucidated. In the current study of one glycocin, sublancin, we identified the phosphoenolpyruvate:sugar phosphotransferase system (PTS) of Bacillus species as a key player in bacterial sensitivity. Sublancin kills several Gram-positive bacteria, such as Bacillus species and Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA). Unlike other classes of bacteriocins for which the PTS is involved in their mechanism of action, we show that the addition of PTS-requiring sugars leads to increased resistance rather than increased sensitivity, suggesting that sublancin has a distinct mechanism of action. Collectively, our present mutagenesis and genomic studies demonstrate that the histidine-containing phosphocarrier protein (HPr) and domain A of enzyme II (PtsG) in particular are critical determinants for bacterial sensitivity to sublancin. PMID:26282429

  14. Photosynthetic Gene Expression in Meristems and during Initial Leaf Development in a C4 Dicotyledonous Plant.

    PubMed

    Ramsperger, V. C.; Summers, R. G.; Berry, J. O.

    1996-08-01

    Immunolocalization and fluorescent in situ hybridization were used with confocal microscopy to examine patterns of photosynthetic gene expression during initial stages of leaf development in the C4 dicot Amaranthus hypochondriacus. mRNAs encoding the large and small subunit of ribulose-1,5-bisphosphate carboxylase were present in the apical dome and in all cells of the leaf primordia. In contrast, these polypeptides were detected only in cells of the ground meristem, with no accumulation detected in the apical dome or in other leaf primordia cells. The ribulose-1,5-bisphosphate carboxylase transcripts showed very little cell-type specificity as leaf structures began to differentiate, whereas their polypeptides accumulated primarily in bundle-sheath precursor cells. Phosphoenolpyruvate carboxylase and pyruvate orthophosphate dikinase mRNAs were abundant in meristems and leaf primordia, although their corresponding polypeptides did not accumulate in leaves until the leaf vascular system began to differentiate. These polypeptides were mostly restricted to premesophyll cells from their earliest detection, whereas their transcripts remained present in nearly all leaf cells. These findings indicate that individual C4 genes are independently regulated as they become initially localized to their appropriate cell types. Furthermore, posttranscriptional regulation plays a major role in determining early patterns of C4 gene expression. PMID:12226343

  15. Discrimination in the dark. Resolving the interplay between metabolic and physical constraints to phosphoenolpyruvate carboxylase activity during the crassulacean acid metabolism cycle.

    PubMed

    Griffiths, Howard; Cousins, Asaph B; Badger, Murray R; von Caemmerer, Susanne

    2007-02-01

    A model defining carbon isotope discrimination (delta13C) for crassulacean acid metabolism (CAM) plants was experimentally validated using Kalanchoe daigremontiana. Simultaneous measurements of gas exchange and instantaneous CO2 discrimination (for 13C and 18O) were made from late photoperiod (phase IV of CAM), throughout the dark period (phase I), and into the light (phase II). Measurements of CO2 response curves throughout the dark period revealed changing phosphoenolpyruvate carboxylase (PEPC) capacity. These systematic changes in PEPC capacity were tracked by net CO2 uptake, stomatal conductance, and online delta13C signal; all declined at the start of the dark period, then increased to a maximum 2 h before dawn. Measurements of delta13C were higher than predicted from the ratio of intercellular to external CO2 (p(i)/p(a)) and fractionation associated with CO2 hydration and PEPC carboxylations alone, such that the dark period mesophyll conductance, g(i), was 0.044 mol m(-2) s(-1) bar(-1). A higher estimate of g(i) (0.085 mol m(-2) s(-1) bar(-1)) was needed to account for the modeled and measured delta18O discrimination throughout the dark period. The differences in estimates of g(i) from the two isotope measurements, and an offset of -5.5 per thousand between the 18O content of source and transpired water, suggest spatial variations in either CO2 diffusion path length and/or carbonic anhydrase activity, either within individual cells or across a succulent leaf. Our measurements support the model predictions to show that internal CO2 diffusion limitations within CAM leaves increase delta13C discrimination during nighttime CO2 fixation while reducing delta13C during phase IV. When evaluating the phylogenetic distribution of CAM, carbon isotope composition will reflect these diffusive limitations as well as relative contributions from C3 and C4 biochemistry. PMID:17142488

  16. Structural and functional analysis of the phosphoenolpyruvate carboxylase gene from the purple nonsulfur bacterium Rhodopseudomonas palustris No. 7.

    PubMed Central

    Inui, M; Dumay, V; Zahn, K; Yamagata, H; Yukawa, H

    1997-01-01

    The ppc gene, encoding phosphoenolpyruvate carboxylase (PEPC), from Rhodopseudomonas palustris No. 7 was cloned and sequenced. Primer extension analysis identified a transcriptional start site 42 bp upstream of the ppc initiation codon. An R. palustris No. 7 PEPC-deficient strain showed a slower doubling time compared with the wild-type strain either anaerobically in the light or aerobically in the dark, when pyruvate was used as a carbon source. PMID:9244286

  17. Effect of Nitrate and Ammonium Nutrition of Nonnodulated Phaseolus vulgaris L. on Phosphoenolpyruvate Carboxylase and Pyruvate Kinase Activity 1

    PubMed Central

    Schweizer, Patrick; Erismann, Karl H.

    1985-01-01

    Young bean plants (Phaseolus vulgaris L. var Saxa) were fed with 3.5 or 10 millimolar N in either the form of NO3− or NH4+, after being grown on N-free nutrient solution for 8 days. The pH of the nutrient solutions was either 6 or 4. The cell sap pH and the extractable activities of phosphoenolpyruvate carboxylase and of pyruvate kinase from roots and primary leaves were measured over several days. The extractable activity of phosphoenolpyruvate carboxylase (based on soluble protein) from primary leaves increased with NO3− nutrition, whereas with NH4+ nutrition and on N-free nutrient solution the activity remained at a low level. Phosphoenopyruvate carboxylase activity from the roots of NH4+-fed plants at pH 4 was finally somewhat higher than from the roots of plants grown on NO3− at the same pH. There was no difference in activity from the root between the N treatments when pH in the nutrient solutions was 6. The extractable activity of pyruvate kinase from roots and primary leaves seemed not to be influenced by the N nutrition of the plants. The results are discussed in relation to the physiological function of both enzymes with special regard to the postulated functions of phosphoenolpyruvate carboxylase in C3 plants as an anaplerotic enzyme and as part of a cellular pH stat. PMID:16664265

  18. Ketogenic diet-fed rats have increased fat mass and phosphoenolpyruvate carboxykinase activity.

    PubMed

    Ribeiro, Letícia C; Chittó, Ana L; Müller, Alexandre P; Rocha, Juliana K; Castro da Silva, Mariane; Quincozes-Santos, André; Nardin, Patrícia; Rotta, Liane N; Ziegler, Denize R; Gonçalves, Carlos-Alberto; Da Silva, Roselis S M; Perry, Marcos L S; Gottfried, Carmem

    2008-11-01

    The ketogenic diet (KD), characterized by high fat and low carbohydrate and protein contents, has been proposed to be beneficial in children with epilepsy disorders not helped by conventional anti-epileptic drug treatment. Weight loss and inadequate growth is an important drawback of this diet and metabolic causes are not well characterized. The aim of this study was to examine body weight variation during KD feeding for 6 wk of Wistar rats; fat mass and adipocyte cytosolic phosphoenolpyruvate carboxykinase (PEPCK) activity were also observed. PEPCK activity was determined based on the [H(14)CO(3) (-)]-oxaloacetate exchange reaction. KD-fed rats gained weight at a less rapid rate than normal-fed rats, but with a significant increment in fat mass. The fat mass/body weight ratio already differed between ketogenic and control rats after the first week of treatment, and was 2.4 x higher in ketogenic rats. The visceral lipogenesis was supported by an increment in adipocyte PEPCK, aiming to provide glycerol 3-phosphate to triacylglycerol synthesis and this fat accumulation was accompanied by glucose intolerance. These data contribute to our understanding of the metabolic effects of the KD in adipose tissue and liver and suggest some potential risks of this diet, particularly visceral fat accumulation. PMID:18655006

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

    PubMed

    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. PMID:25288791

  20. The role of phosphoenolpyruvate carboxykinase in neuronal steroidogenesis under acute inflammation.

    PubMed

    Sadasivam, Mohanraj; Ramatchandirin, Balamurugan; Balakrishnan, Sivasangari; Selvaraj, Karthikeyan; Prahalathan, Chidambaram

    2014-12-01

    Phosphoenolpyruvate carboxykinase (PEPCK) is a key gluconeogenic enzyme found in many tissues throughout the body including brain. In the present study, we have investigated the effect of bacterial lipopolysaccharide (LPS) on PEPCK and its role in neuronal steroidogenesis. Adult female albino rats were administered LPS (5mg/kg body weight) to induce acute inflammation. LPS administration resulted in a significant increase of PEPCK mRNA expression with concomitant increase in mRNA levels of steroidogenic acute regulatory (StAR) protein and other steroidogenic enzymes including 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) and aromatase in brain tissue. Further, the inhibition of PEPCK expression by glipizide significantly decreased the mRNA expression of steroidogenic proteins and concurrently increased the mRNA levels of proinflammatory cytokines under LPS administration. The results of this study suggest a novel finding that PEPCK may have an important role in neuronal steroidogenesis; which serves as an adaptive response under inflammation. PMID:25256278

  1. Utilization of Substrate Intrinsic Binding Energy for Conformational Change and Catalytic Function in Phosphoenolpyruvate Carboxykinase.

    PubMed

    Johnson, Troy A; Mcleod, Matthew J; Holyoak, Todd

    2016-01-26

    Phosphoenolpyruvate carboxykinase (PEPCK) is an essential metabolic enzyme operating in the gluconeogenesis and glyceroneogenesis pathways. Previous work has demonstrated that the enzyme cycles between a catalytically inactive open state and a catalytically active closed state. The transition of the enzyme between these states requires the transition of several active site loops to shift from mobile, disordered structural elements to stable ordered states. The mechanism by which these disorder-order transitions are coupled to the ligation state of the active site however is not fully understood. To further investigate the mechanisms by which the mobility of the active site loops is coupled to enzymatic function and the transitioning of the enzyme between the two conformational states, we have conducted structural and functional studies of point mutants of E89. E89 is a proposed key member of the interaction network of mobile elements as it resides in the R-loop region of the enzyme active site. These new data demonstrate the importance of the R-loop in coordinating interactions between substrates at the OAA/PEP binding site and the mobile R- and Ω-loop domains. In turn, the studies more generally demonstrate the mechanisms by which the intrinsic ligand binding energy can be utilized in catalysis to drive unfavorable conformational changes, changes that are subsequently required for both optimal catalytic activity and fidelity. PMID:26709450

  2. Mycobacterium tuberculosis phosphoenolpyruvate carboxykinase is regulated by redox mechanisms and interaction with thioredoxin.

    PubMed

    Machová, Iva; Snašel, Jan; Zimmermann, Michael; Laubitz, Daniel; Plocinski, Przemyslaw; Oehlmann, Wulf; Singh, Mahavir; Dostál, Jiři; Sauer, Uwe; Pichová, Iva

    2014-05-01

    Tuberculosis remains a major health concern worldwide. Eradication of its causative agent, the bacterial pathogen Mycobacterium tuberculosis, is particularly challenging due to a vast reservoir of latent carriers of the disease. Despite the misleading terminology of a so-called dormant state associated with latent infections, the bacteria have to maintain basic metabolic activities. Hypoxic conditions have been widely used as an in vitro system to study this dormancy. Such studies identified a rearrangement of central carbon metabolism to exploit fermentative processes caused by the lack of oxygen. Phosphoenolpyruvate carboxykinase (Pck; EC 4.1.1.32) is the enzyme at the center of these metabolic rearrangements. Although Pck is associated with gluconeogenesis under standard growth conditions, the enzyme can catalyze the reverse reaction, supporting anaplerosis of the tricarboxylic acid cycle, under conditions leading to slowed or stopped bacterial replication. To study the mechanisms that regulate the switch between two Pck functions, we systematically investigated factors influencing the gluconeogenic and anaplerotic reaction kinetics. We demonstrate that a reducing environment, as found under hypoxia-triggered non-replicating conditions, accelerates the reaction in the anaplerotic direction. Furthermore, we identified proteins that interact with Pck. The interaction between Pck and the reduced form of mycobacterial thioredoxin, gene expression of which is increased under hypoxic conditions, also increased the Pck anaplerotic activity. We thus propose that a reducing environment and the protein-protein interaction with thioredoxin in particular enable the Pck anaplerotic function under fermentative growth conditions. PMID:24659783

  3. Deregulation of feedback inhibition of phosphoenolpyruvate carboxylase for improved lysine production in Corynebacterium glutamicum.

    PubMed

    Chen, Zhen; Bommareddy, Rajesh Reddy; Frank, Doinita; Rappert, Sugima; Zeng, An-Ping

    2014-02-01

    Allosteric regulation of phosphoenolpyruvate carboxylase (PEPC) controls the metabolic flux distribution of anaplerotic pathways. In this study, the feedback inhibition of Corynebacterium glutamicum PEPC was rationally deregulated, and its effect on metabolic flux redistribution was evaluated. Based on rational protein design, six PEPC mutants were designed, and all of them showed significantly reduced sensitivity toward aspartate and malate inhibition. Introducing one of the point mutations (N917G) into the ppc gene, encoding PEPC of the lysine-producing strain C. glutamicum LC298, resulted in ∼37% improved lysine production. In vitro enzyme assays and (13)C-based metabolic flux analysis showed ca. 20 and 30% increases in the PEPC activity and corresponding flux, respectively, in the mutant strain. Higher demand for NADPH in the mutant strain increased the flux toward pentose phosphate pathway, which increased the supply of NADPH for enhanced lysine production. The present study highlights the importance of allosteric regulation on the flux control of central metabolism. The strategy described here can also be implemented to improve other oxaloacetate-derived products. PMID:24334667

  4. Abiotic stresses affecting water balance induce phosphoenolpyruvate carboxylase expression in roots of wheat seedlings.

    PubMed

    González, María-Cruz; Sánchez, Rosario; Cejudo, Francisco J

    2003-04-01

    Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) plays an important role in CO(2) fixation in C4 and CAM plants. In C3 plants, PEPC is widely expressed in most organs; however, its function is not yet clearly established. With the aim of providing clues on the function of PEPC in C3 plants, we have analyzed its pattern of expression in wheat ( Triticum aestivum L.) seedlings. Roots showed almost double the level of PEPC activity of shoots. Further analysis of PEPC expression in roots by in situ localization techniques showed a high accumulation of PEPC transcripts and polypeptides in meristematic cells, whereas in the rest of the root PEPC localized preferentially to the vascular tissue. Treatment with NaCl and LiCl induced PEPC expression in roots. Similarly, other abiotic stresses affecting water status, such as drought or cold, induced PEPC expression. Induction was root-specific except for the cold treatment, which also induced PEPC in shoots, although to a lesser extent. In contrast, hypoxia, which does not affect water balance, did not promote any induction of PEPC expression. These results suggest an important role for this enzyme in the adaptation of plants to environmental changes. PMID:12687366

  5. Phosphoenolpyruvate carboxylase from cherimoya fruit: properties, kinetics and effects of high CO(2).

    PubMed

    Muñoz, T; Escribano, M I; Merodio, C

    2001-12-01

    Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) regulatory properties were studied in non-photosynthetic (mesocarp) and photosynthetic (peel) tissues from cherimoya (Annona cherimola Mill.) fruit stored in air, in order to gain a better understanding of in vivo enzyme regulation. Analyses were also performed with fruit treated with 20% CO(2)-20% O(2) to define the role of PEPC as part of an adaptive mechanism to high external carbon dioxide levels. The results revealed that the special kinetic characteristics of the enzyme from mesocarp--high V(max) and low sensibility to L-malate inhibition - are related to the active acid metabolism of these fruits and point to a high rate of reassimilation of respired CO(2) into keto-acids. With respect to fruit stored in air, PEPC in crude extracts from CO(2)-treated cherimoyas gave a similar V(max) (1.12+/-0.03 microkat x mg(-1) protein), a lower apparent K(m) (68+/-9 microM for PEP) and a higher I(50) of L-malate (5.95+/-0.3 mM). These kinetic values showed the increase in the affinity of this enzyme toward one of its substrate, PEP, by elevated external CO(2) concentrations. The lower K(m) value and lower sensitivity to L-malate are consistent with higher in vivo carboxylation reaction efficiency in CO(2)-treated cherimoyas, while pointing to an additional enzyme regulation system via CO(2). PMID:11730863

  6. Improvement of the phosphoenolpyruvate carboxylase activity of Phaeodactylum tricornutum PEPCase 1 through protein engineering.

    PubMed

    Chang, Kwang Suk; Jeon, Hancheol; Seo, Seungbeom; Lee, Yew; Jin, EonSeon

    2014-06-10

    In order to mitigate CO2 accumulation and decrease the rate of global warming and climate change, we previously presented a strategy for the development of an efficient CO2 capture and utilization system. The system employs two recombinant enzymes, carbonic anhydrase and phosphoenolpyruvate carboxylase, which were originated from microalgae. Although utilization of this integrated system would require a large quantity of high quality PEPCase protein, such quantities could be produced by increasing the solubility of the Phaeodactylum tricornutum PEPCase 1 (PtPEPCase 1) protein in the Escherichia coli heterologous expression system. We first expressed the putative mitochondria targeting peptide- and chloroplast transit peptide-truncated proteins of PtPEPCase 1, mPtPEPCase 1 and cPtPEPCase 1, respectively, in E. coli. After affinity chromatography, the amount of purified PEPCase protein from 500mL of E. coli culture was greatest for cPtPEPCase 1 (1.99mg), followed by mPtPEPCase 1 (0.82mg) and PtPEPCase 1 (0.61mg). Furthermore, the enzymatic activity of mPtPEPCase 1 and cPtPEPCase 1 showed approximately 1.6-fold (32.19 units/mg) and 3-fold (59.48 units/mg) increases, respectively. Therefore, cPtPEPCase 1 purified using the E. coli heterogeneous expression system could be a strong candidate for a platform technology to capture CO2 and produce value-added four-carbon platform chemicals. PMID:24835101

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

    PubMed

    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. PMID:24497630

  8. Control of Transposon-mediated Directed Mutation by the Escherichia coli Phosphoenolpyruvate:Sugar Phosphotransferase System

    PubMed Central

    Saier, Milton H.; Zhang, Zhongge

    2015-01-01

    The phosphoenolpyruvate:sugar phosphotransferase system (PTS) has been shown to control transport, cell metabolism and gene expression. We here present results supporting the novel suggestion that in certain instances, it also regulates mutation rate. Directed mutations are defined as mutations that occur at higher frequencies when beneficial than when neutral or detrimental. To date, the occurrence of directed point mutations has not been documented and confirmed, but a few examples of transposon-mediated directed mutation have been reported. Here we focus on the first and best-studied example of directed mutation, which involves the regulation of Insertion Sequence-5 (IS5) hopping into a specific site upstream of the glpFK glycerol utilization operon in Escherichia coli. This insertional event specifically activates expression of the glpFK operon, allowing growth of wild type cells with glycerol as a carbon source in the presence of non-metabolizable glucose analogues which normally block glycerol utilization. The sugar transporting PTS controls this process by regulating levels of cytoplasmic glycerol-3-phosphate and cyclic AMP as established in previous publications. Direct involvement of the glycerol repressor, GlpR, and the cyclic AMP receptor protein, Crp, in the regulation of transposon-mediated directed mutation has been demonstrated. PMID:26159081

  9. Trypanosoma evansi contains two auxiliary enzymes of glycolytic metabolism: Phosphoenolpyruvate carboxykinase and pyruvate phosphate dikinase.

    PubMed

    Rivero, Luz Amira; Concepción, Juan Luis; Quintero-Troconis, Ender; Quiñones, Wilfredo; Michels, Paul A M; Acosta, Héctor

    2016-06-01

    Trypanosoma evansi is a monomorphic protist that can infect horses and other animal species of economic importance for man. Like the bloodstream form of the closely related species Trypanosoma brucei, T. evansi depends exclusively on glycolysis for its free-energy generation. In T. evansi as in other kinetoplastid organisms, the enzymes of the major part of the glycolytic pathway are present within organelles called glycosomes, which are authentic but specialized peroxisomes. Since T. evansi does not undergo stage-dependent differentiations, it occurs only as bloodstream forms, it has been assumed that the metabolic pattern of this parasite is identical to that of the bloodstream form of T. brucei. However, we report here the presence of two additional enzymes, phosphoenolpyruvate carboxykinase and PPi-dependent pyruvate phosphate dikinase in T. evansi glycosomes. Their colocalization with glycolytic enzymes within the glycosomes of this parasite has not been reported before. Both enzymes can make use of PEP for contributing to the production of ATP within the organelles. The activity of these enzymes in T. evansi glycosomes drastically changes the model assumed for the oxidation of glucose by this parasite. PMID:26968775

  10. Stereochemical course of the reactions catalyzed by the bacterial phosphoenolpyruvate: Mannitol phosphotransferase system

    SciTech Connect

    Mueller, E.G.; Knowles, J.R. ); Khandekar, S.S.; Jacobson, G.R. )

    1990-07-24

    The authors have determined the overall stereochemical course of the reactions leading to the phosphorylation of D-mannitol by mannitol-specific enzyme II (EII{sup Mtl}) of the Escherichia coli phosphoenolpyruvate- (PEP) dependent phosphotransferase system (PTS). In the presence of enzyme I and HPr of the PTS, and of membranes containing EII{sup Mtl}, the phospho group from ((R)-{sup 16}O, {sup 17}O, {sup 18}O)PEP was transferred to D-mannitol to form mannitol 1-phosphate with overall inversion of the configuration at phosphorus with respect to that of PEP. Since in the course of these reactions enzyme I and HPr are each covalently phosphorylated at a single site and inversion of the chiral phospho group from PEP indicates an odd number of transfer steps overall, transfer from phospho-HPr to mannitol via EII{sup Mtl} must also occur in an odd number of steps. Taken together with the fact that catalytically important phospho-EII{sup Mtl} intermediates have been demonstrated biochemically, the results imply that EII{sup Mtl} is sequentially phosphorylated at two different sites during phospho transfer from phospho-HPr to mannitol. This conclusion is consistent with the available evidence on phospho-EII{sup Mtl} intermediates and in particular with the recent report that two different phospho peptides can be isolated from the fully phosphorylated protein.

  11. Metal Ion Interactions with Phosphoenolpyruvate Carboxylase from Crassula argentea and Zea mays1

    PubMed Central

    Nguyen, Tien T.; Ngam-ek, Apinya; Jenkins, Joane; Grover, Scott D.

    1988-01-01

    Metal ion interactions with phosphoenolpyruvate carboxylase from the CAM plant Crassula argentea and the C4 plant Zea mays were kinetically analyzed. Fe2+ and Cd2+ were found to be active metal cofactors along with the previously known active metals Mg2+, Mn2+, and Co2+. In studies with the Crassula enzyme, Mg2+ yielded the highest Vmax value but also generated the highest values of Km(metal) and Km(pep). For these five active metals lower Km(metal) values tended to be associated with lower Km(pep) values. PEP saturation curves showed more kinetic cooperativity than the corresponding metal saturation curves. The activating metal ions all have ionic radii in the range of 0.86 to 1.09 Å. Ca2+, Sr2+, Ba2+, and Ni2+ inhibited competitively with respect to Mg2+, whereas Be2+, Cu2+, Zn2+, and Pd2+ showed mixed-type inhibition. Vmax trends with the five active metals were similar for the C. argentea and Z. mays enzymes except that Cd2+ was less effective with the maize enzyme. Km(metal) values were 10- to 60-fold higher in the enzyme from Z. mays. PMID:16665847

  12. Cytosolic phosphoenolpyruvate carboxykinase deficiency presenting with acute liver failure following gastroenteritis.

    PubMed

    Santra, Saikat; Cameron, Jessie M; Shyr, Casper; Zhang, Linhua; Drögemöller, Britt; Ross, Colin J; Wasserman, Wyeth W; Wevers, Ron A; Rodenburg, Richard J; Gupte, Girish; Preece, Mary Anne; van Karnebeek, Clara D

    2016-05-01

    We report a patient from a consanguineous family who presented with transient acute liver failure and biochemical patterns suggestive of disturbed urea cycle and mitochondrial function, for whom conventional genetic and metabolic investigations for acute liver failure failed to yield a diagnosis. Whole exome sequencing revealed a homozygous 12-bp deletion in PCK1 (MIM 614168) encoding cytosolic phosphoenolpyruvate carboxykinase (PEPCK); enzymatic studies subsequently confirmed its pathogenic nature. We propose that PEPCK deficiency should be considered in the young child with unexplained liver failure, especially where there are marked, accumulations of TCA cycle metabolites on urine organic acid analysis and/or an amino acid profile with hyperammonaemia suggestive of a proximal urea cycle defect during the acute episode. If suspected, intravenous administration of dextrose should be initiated. Long-term management comprising avoidance of fasting with the provision of a glucose polymer emergency regimen for illness management may be sufficient to prevent future episodes of liver failure. This case report provides further insights into the (patho-)physiology of energy metabolism, confirming the power of genomic analysis of unexplained biochemical phenotypes. PMID:26971250

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

    PubMed Central

    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

  14. An assessment of the capacity for phosphoenolpyruvate carboxykinase to contribute to C4 photosynthesis.

    PubMed

    Koteyeva, Nuria K; Voznesenskaya, Elena V; Edwards, Gerald E

    2015-06-01

    Three C4 acid decarboxylases, phosphoenolpyruvate carboxykinase (PEPCK), NADP-malic enzyme (NADP-ME), and NAD-malic enzyme (NAD-ME) were recruited from C3 plants to support C4 photosynthesis. In Poaceae, there are established lineages having PEPCK type species, and some NADP-ME lineages in which PEPCK contributes to C4. Besides family Poaceae, recently PEPCK has been reported to function in C4 photosynthesis in eudicot species including Cleome gynandra (Cleomaceae), Trianthema portulacastrum and Zaleya pentandra (Aizoaceae). We evaluated PEPCK by enzyme assay and western blots in representatives of Poaceae, Aizoaceae, Cleomaceae, and Chenopodiaceae compared to that in the PEPCK type C4 grass Spartina anglica. Eragrostis nutans was identified as the first NAD-ME type C4 grass having substantial amounts of PEPCK. In the eudicots, including C. gynandra, Cleome angustifolia, T. portulacastrum, Z. pentandra, and nine C4 members of family Chenopodiaceae (which has the most C4 species and diversity in forms among eudicot families), amounts of PEPCK were generally very low (barely detectable up to 4% of that in S. anglica). Based on these results, C4 species can be classified biochemically according to the dominant decarboxylase recruited for C4 function; and, Poaceae remains the only family in which PEPCK is known to have a significant role in C4 photosynthesis. PMID:25900567

  15. Multiple Inter-Kingdom Horizontal Gene Transfers in the Evolution of the Phosphoenolpyruvate Carboxylase Gene Family

    PubMed Central

    Wang, Wen; Su, Bing

    2012-01-01

    Pepcase is a gene encoding phosphoenolpyruvate carboxylase that exists in bacteria, archaea and plants,playing an important role in plant metabolism and development. Most plants have two or more pepcase genes belonging to two gene sub-families, while only one gene exists in other organisms. Previous research categorized one plant pepcase gene as plant-type pepcase (PTPC) while the other as bacteria-type pepcase (BTPC) because of its similarity with the pepcase gene found in bacteria. Phylogenetic reconstruction showed that PTPC is the ancestral lineage of plant pepcase, and that all bacteria, protistpepcase and BTPC in plants are derived from a lineage of pepcase closely related with PTPC in algae. However, their phylogeny contradicts the species tree and traditional chronology of organism evolution. Because the diversification of bacteria occurred much earlier than the origin of plants, presumably all bacterialpepcase derived from the ancestral PTPC of algal plants after divergingfrom the ancestor of vascular plant PTPC. To solve this contradiction, we reconstructed the phylogeny of pepcase gene family. Our result showed that both PTPC and BTPC are derived from an ancestral lineage of gamma-proteobacteriapepcases, possibly via an ancient inter-kingdom horizontal gene transfer (HGT) from bacteria to the eukaryotic common ancestor of plants, protists and cellular slime mold. Our phylogenetic analysis also found 48other pepcase genes originated from inter-kingdom HGTs. These results imply that inter-kingdom HGTs played important roles in the evolution of the pepcase gene family and furthermore that HGTsare a more frequent evolutionary event than previouslythought. PMID:23251445

  16. Transcriptional regulation of the phosphoenolpyruvate carboxykinase gene by cooperation between hepatic nuclear factors.

    PubMed Central

    Yanuka-Kashles, O; Cohen, H; Trus, M; Aran, A; Benvenisty, N; Reshef, L

    1994-01-01

    To study the transcriptional regulation of the liver gluconeogenic phenotype, the underdifferentiated mouse Hepa-1c1c7 (Hepa) hepatoma cell line was used. These cells mimicked the fetal liver by appreciably expressing the alpha-fetoprotein and albumin genes but not the phosphoenolpyruvate carboxykinase (PEPCK) gene. Unlike the fetal liver, however, Hepa cells failed to express the early-expressed factors hepatocyte nuclear factor 1 alpha (HNF-1 alpha) and HNF-4 and the late-expressed factor C/EBP alpha, thereby providing a suitable system for examining possible cooperation between these factors in the transcriptional regulation of the PEPCK gene. Transient transfection assays of a chimeric PEPCK-chloramphenicol acetyltransferase construct showed a residual PEPCK promoter activity in the Hepa cell line, which was slightly stimulated by cotransfection with a single transcription factor from either the C/EBP family or HNF-1 alpha but not at all affected by cotransfection of HNF-4. In contrast, cotransfection of the PEPCK construct with members from the C/EBP family plus HNF-1 alpha resulted in a synergistic stimulation of the PEPCK promoter activity. This synergistic effect depended on the presence in the PEPCK promoter region of the HNF-1 recognition sequence and on the presence of two C/EBP recognition sequences. The results demonstrate a requirement for coexistence and cooperation between early and late liver-enriched transcription factors in the transcriptional regulation of the PEPCK gene. In addition, the results suggest redundancy between members of the C/EBP family of transcription factors in the regulation of PEPCK gene expression. Images PMID:7935427

  17. Regulation of the acuF Gene, Encoding Phosphoenolpyruvate Carboxykinase in the Filamentous Fungus Aspergillus nidulans

    PubMed Central

    Hynes, Michael J.; Draht, Oliver W.; Davis, Meryl A.

    2002-01-01

    Phosphoenolpyruvate carboxykinase (PEPCK) is a key enzyme required for gluconeogenesis when microorganisms grow on carbon sources metabolized via the tricarboxylic acid (TCA) cycle. Aspergillus nidulans acuF mutants isolated by their inability to use acetate as a carbon source specifically lack PEPCK. The acuF gene has been cloned and shown to encode a protein with high similarity to PEPCK from bacteria, plants, and fungi. The regulation of acuF expression has been studied by Northern blotting and by the construction of lacZ fusion reporters. Induction by acetate is abolished in mutants unable to metabolize acetate via the TCA cycle, and induction by amino acids metabolized via 2-oxoglutarate is lost in mutants unable to form 2-oxoglutarate. Induction by acetate and proline is not additive, consistent with a single mechanism of induction. Malate and succinate result in induction, and it is proposed that PEPCK is controlled by a novel mechanism of induction by a TCA cycle intermediate or derivative, thereby allowing gluconeogenesis to occur during growth on any carbon source metabolized via the TCA cycle. It has been shown that the facB gene, which mediates acetate induction of enzymes specifically required for acetate utilization, is not directly involved in PEPCK induction. This is in contrast to Saccharomyces cerevisiae, where Cat8p and Sip4p, homologs of FacB, regulate PEPCK as well as the expression of other genes necessary for growth on nonfermentable carbon sources in response to the carbon source present. This difference in the control of gluconeogenesis reflects the ability of A. nidulans and other filamentous fungi to use a wide variety of carbon sources in comparison with S. cerevisiae. The acuF gene was also found to be subject to activation by the CCAAT binding protein AnCF, a protein homologous to the S. cerevisiae Hap complex and the mammalian NFY complex. PMID:11741859

  18. Effects of phosphoenolpyruvate carboxylase desensitization on glutamic acid production in Corynebacterium glutamicum ATCC 13032.

    PubMed

    Wada, Masaru; Sawada, Kazunori; Ogura, Kotaro; Shimono, Yuta; Hagiwara, Takuya; Sugimoto, Masakazu; Onuki, Akiko; Yokota, Atsushi

    2016-02-01

    Phosphoenolpyruvate carboxylase (PEPC) in Corynebacterium glutamicum ATCC13032, a glutamic-acid producing actinobacterium, is subject to feedback inhibition by metabolic intermediates such as aspartic acid and 2-oxoglutaric acid, which implies the importance of PEPC in replenishing oxaloacetic acid into the TCA cycle. Here, we investigated the effects of feedback-insensitive PEPC on glutamic acid production. A single amino-acid substitution in PEPC, D299N, was found to relieve the feedback control by aspartic acid, but not by 2-oxoglutaric acid. A simple mutant, strain R1, having the D299N substitution in PEPC was constructed from ATCC 13032 using the double-crossover chromosome replacement technique. Strain R1 produced glutamic acid at a concentration of 31.0 g/L from 100 g/L glucose in a jar fermentor culture under biotin-limited conditions, which was significantly higher than that of the parent, 26.0 g/L (1.19-fold), indicative of the positive effect of desensitized PEPC on glutamic acid production. Another mutant, strain DR1, having both desensitized PEPC and PYK-gene deleted mutations, was constructed in a similar manner using strain D1 with a PYK-gene deleted mutation as the parent. This mutation had been shown to enhance glutamic acid production in our previous study. Although marginal, strain D1 produced higher glutamic acid, 28.8 g/L, than ATCC13032 (1.11-fold). In contrast, glutamic acid production by strain DR-1 was elevated up to 36.9 g/L, which was 1.42-fold higher than ATCC13032 and significantly higher than the other three strains. The results showed a synergistic effect of these two mutations on glutamic acid production in C. glutamicum. PMID:26168906

  19. In vivo monoubiquitination of anaplerotic phosphoenolpyruvate carboxylase occurs at Lys624 in germinating sorghum seeds.

    PubMed

    Ruiz-Ballesta, Isabel; Feria, Ana-Belén; Ni, Hong; She, Yi-Min; Plaxton, William Charles; Echevarría, Cristina

    2014-02-01

    Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is an important cytosolic regulatory enzyme that plays a pivotal role in numerous physiological processes in plants, including seed development and germination. Previous studies demonstrated the occurrence of immunoreactive PEPC polypeptides of ~110 kDa and 107 kDa (p110 and p107, respectively) on immunoblots of clarified extracts of germinating sorghum (Sorghum bicolor) seeds. In order to establish the biochemical basis for this observation, a 460 kDa PEPC heterotetramer composed of an equivalent ratio of p110 and p107 subunits was purified to near homogeneity from the germinated seeds. Mass spectrometry established that p110 and p107 are both encoded by the same plant-type PEPC gene (CP21), but that p107 was in vivo monoubiquitinated at Lys624 to form p110. This residue is absolutely conserved in vascular plant PEPCs and is proximal to a PEP-binding/catalytic domain. Anti-ubiquitin IgG immunodetected p110 but not p107, whereas incubation with a deubiquitinating enzyme (USP-2 core) efficiently converted p110 into p107, while relieving the enzyme's feedback inhibition by L-malate. Partial PEPC monoubiquitination was also detected during sorghum seed development. It is apparent that monoubiquitination at Lys624 is opposed to phosphorylation at Ser7 in terms of regulating the catalytic activity of sorghum seed PEPC. PEPC monoubiquitination is hypothesized to fine-tune anaplerotic carbon flux according to the cell's immediate physiological requirements for tricarboxylic acid cycle intermediates needed in support of biosynthesis and carbon-nitrogen interactions. PMID:24288181

  20. Developmental and molecular physiological evidence for the role of phosphoenolpyruvate carboxylase in rapid cotton fibre elongation.

    PubMed

    Li, Xiao-Rong; Wang, Lu; Ruan, Yong-Ling

    2010-01-01

    Cotton fibres are hair-like single-cells that elongate to several centimetres long after their initiation from the ovule epidermis at anthesis. The accumulation of malate, along with K+ and sugars, is thought to play an important role in fibre elongation through osmotic regulation and charge balance. However, there is a lack of evidence for or against such an hypothesis. Phosphoenolpyruvate carboxylase (PEPC) is a key enzyme responsible for the synthesis of malate. The potential role of PEPC in cotton fibre elongation is examined here. Developmentally, PEPC activity was higher at the rapid elongation phase than that at the slow elongation stage. Genotypically, PEPC activity correlated positively with the rate of fibre elongation and the final fibre length attained. Importantly, suppression of PEPC activity by LiCl that reduces its phosphorylation status decreased fibre length. To examine the molecular basis underlying PEPC activity, two cDNAs encoding PEPC, GhPEPC1 and 2, were cloned, which represents the major PEPC genes expressed in cotton fibre. RT-PCR analyses revealed that GhPEPC1 and 2 were highly expressed at the rapid elongation phase but weakly at the slow-to-terminal elongation period. In situ hybridization detected mRNA of GhPEPC1 and 2 in 1 d young fibres but not in the ovule epidermis prior to fibre initiation. Collectively, the data indicate that cotton fibre elongation requires high activity of PEPC, probably through the expression of the GhPEPC1 and 2 genes. PMID:19815688

  1. Functional analysis of putative phosphoenolpyruvate transporters localized to the Golgi apparatus in Schizosaccharomyces pombe.

    PubMed

    Yoritsune, Ken-ichi; Higuchi, Yujiro; Matsuzawa, Tomohiko; Takegawa, Kaoru

    2014-11-01

    The cell surface of Schizosaccharomyces pombe is negatively charged due to the presence of pyruvylated oligosaccharides, which is important for cell-cell recognition. However, the mechanism of pyruvate supply to oligosaccharides is not clearly understood. Here, we analyzed three putative phosphoenolpyruvate (PEP) transporter genes (pet1(+) , pet2(+) , and pet3(+) ) in S. pombe, identified by sequence homology search against the Arabidopsis thaliana PEP transporter AtPPT1. Schizosaccharomyces pombe strain carrying a disruption in pet1(+) (pet1Δ) or in pet2(+) (pet2Δ), but not the strain carrying a disruption in pet3(+) (pet3Δ), showed reduced pyruvate level on the cell surface. This reduction in pyruvate level was restored to the control level by expressing green fluorescent protein (GFP)-tagged Pet1p and Pet2p in respective disruptants. Fluorescence microscope studies revealed that GFP-tagged Pet1p and Pet2p were localized to the Golgi apparatus. Although expression of neither AtPPT1 nor AtPPT2 suppressed the pet1Δ phenotype, that of chimeric constructs, where the N-terminal regions of AtPPT1 and AtPPT2 were replaced by the N-terminal region of Pet1p, partially suppressed the pet1Δ phenotype. Furthermore, the reduction in cell surface negative charge in pet1Δ cells was restored by incubating these cells with recombinant Pvg1p and PEP. Thus, Pet1p and Pet2p are likely involved in transporting PEP from the cytoplasm into the Golgi. PMID:25195688

  2. In vivo monoubiquitination of anaplerotic phosphoenolpyruvate carboxylase occurs at Lys624 in germinating sorghum seeds

    PubMed Central

    Echevarría, Cristina

    2014-01-01

    Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is an important cytosolic regulatory enzyme that plays a pivotal role in numerous physiological processes in plants, including seed development and germination. Previous studies demonstrated the occurrence of immunoreactive PEPC polypeptides of ~110kDa and 107kDa (p110 and p107, respectively) on immunoblots of clarified extracts of germinating sorghum (Sorghum bicolor) seeds. In order to establish the biochemical basis for this observation, a 460kDa PEPC heterotetramer composed of an equivalent ratio of p110 and p107 subunits was purified to near homogeneity from the germinated seeds. Mass spectrometry established that p110 and p107 are both encoded by the same plant-type PEPC gene (CP21), but that p107 was in vivo monoubiquitinated at Lys624 to form p110. This residue is absolutely conserved in vascular plant PEPCs and is proximal to a PEP-binding/catalytic domain. Anti-ubiquitin IgG immunodetected p110 but not p107, whereas incubation with a deubiquitinating enzyme (USP-2 core) efficiently converted p110 into p107, while relieving the enzyme’s feedback inhibition by l-malate. Partial PEPC monoubiquitination was also detected during sorghum seed development. It is apparent that monoubiquitination at Lys624 is opposed to phosphorylation at Ser7 in terms of regulating the catalytic activity of sorghum seed PEPC. PEPC monoubiquitination is hypothesized to fine-tune anaplerotic carbon flux according to the cell’s immediate physiological requirements for tricarboxylic acid cycle intermediates needed in support of biosynthesis and carbon–nitrogen interactions. PMID:24288181

  3. Association of phosphoenolpyruvate phosphatase activity with the cytosolic pyruvate kinase of germinating mung beans.

    PubMed

    Podestá, F E; Plaxton, W C

    1991-12-01

    The procedure of Malhotra and Kayastha ([1990] Plant Physiology 93: 194-200) for the purification to homogeneity of a phosphoenolpyruvate-specific alkaline phosphatase (PEP phosphatase) from germinating mung beans (Vigna radiata) was followed. Although a higher specific activity of 1.4 micromoles pyruvate produced per minute per milligram protein was obtained, the final preparation was less than 10% pure as judged by polyacrylamide gel electrophoresis. Attempts to further purify the enzyme resulted in loss of activity. The partially purified enzyme contained significant pyruvate kinase activity (0.13 micromole pyruvate produced per minute per milligram protein) when assayed at pH 7.2, but not at pH 8.5. The PEP phosphatase activity of the final preparation exhibited hysteresis; a lag time of 5 to 6 minutes was required before a steady-state reaction rate was attained. A western blot of the final preparation revealed an immunoreactive 57 kilodalton polypeptide when probed with monospecific rabbit polyclonal antibodies prepared against germinating castor bean cytosolic pyruvate kinase. No antigenic cross-reaction of the final preparation was observed with antibodies against castor bean leucoplast pyruvate kinase, or black mustard PEP-specific acid phosphatase. Nondenaturing polyacrylamide gel electrophoresis of the final preparation resulted in a single PEP phosphatase activity band; when this band was excised and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blotting, a 57 kilodalton silver-staining polypeptide was obtained that strongly cross-reacted with the anti-(cytosolic pyruvate kinase) immunoglobulin G. It is suggested that mung bean PEP-specific alkaline phosphatase activity is due to cytosolic pyruvate kinase, in which pyruvate and ortho-phosphate are formed in the absence of ADP. PMID:16668551

  4. Association of Phosphoenolpyruvate Phosphatase Activity with the Cytosolic Pyruvate Kinase of Germinating Mung Beans 1

    PubMed Central

    Podestá, Florencio E.; Plaxton, William C.

    1991-01-01

    The procedure of Malhotra and Kayastha ([1990] Plant Physiology 93: 194-200) for the purification to homogeneity of a phosphoenolpyruvate-specific alkaline phosphatase (PEP phosphatase) from germinating mung beans (Vigna radiata) was followed. Although a higher specific activity of 1.4 micromoles pyruvate produced per minute per milligram protein was obtained, the final preparation was less than 10% pure as judged by polyacrylamide gel electrophoresis. Attempts to further purify the enzyme resulted in loss of activity. The partially purified enzyme contained significant pyruvate kinase activity (0.13 micromole pyruvate produced per minute per milligram protein) when assayed at pH 7.2, but not at pH 8.5. The PEP phosphatase activity of the final preparation exhibited hysteresis; a lag time of 5 to 6 minutes was required before a steady-state reaction rate was attained. A western blot of the final preparation revealed an immunoreactive 57 kilodalton polypeptide when probed with monospecific rabbit polyclonal antibodies prepared against germinating castor bean cytosolic pyruvate kinase. No antigenic cross-reaction of the final preparation was observed with antibodies against castor bean leucoplast pyruvate kinase, or black mustard PEP-specific acid phosphatase. Nondenaturing polyacrylamide gel electrophoresis of the final preparation resulted in a single PEP phosphatase activity band; when this band was excised and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blotting, a 57 kilodalton silver-staining polypeptide was obtained that strongly cross-reacted with the anti-(cytosolic pyruvate kinase) immunoglobulin G. It is suggested that mung bean PEP-specific alkaline phosphatase activity is due to cytosolic pyruvate kinase, in which pyruvate and ortho-phosphate are formed in the absence of ADP. ImagesFigure 1Figure 2 PMID:16668551

  5. Multiple inter-kingdom horizontal gene transfers in the evolution of the phosphoenolpyruvate carboxylase gene family.

    PubMed

    Peng, Yingmei; Cai, Jing; Wang, Wen; Su, Bing

    2012-01-01

    Pepcase is a gene encoding phosphoenolpyruvate carboxylase that exists in bacteria, archaea and plants,playing an important role in plant metabolism and development. Most plants have two or more pepcase genes belonging to two gene sub-families, while only one gene exists in other organisms. Previous research categorized one plant pepcase gene as plant-type pepcase (PTPC) while the other as bacteria-type pepcase (BTPC) because of its similarity with the pepcase gene found in bacteria. Phylogenetic reconstruction showed that PTPC is the ancestral lineage of plant pepcase, and that all bacteria, protistpepcase and BTPC in plants are derived from a lineage of pepcase closely related with PTPC in algae. However, their phylogeny contradicts the species tree and traditional chronology of organism evolution. Because the diversification of bacteria occurred much earlier than the origin of plants, presumably all bacterialpepcase derived from the ancestral PTPC of algal plants after divergingfrom the ancestor of vascular plant PTPC. To solve this contradiction, we reconstructed the phylogeny of pepcase gene family. Our result showed that both PTPC and BTPC are derived from an ancestral lineage of gamma-proteobacteriapepcases, possibly via an ancient inter-kingdom horizontal gene transfer (HGT) from bacteria to the eukaryotic common ancestor of plants, protists and cellular slime mold. Our phylogenetic analysis also found 48other pepcase genes originated from inter-kingdom HGTs. These results imply that inter-kingdom HGTs played important roles in the evolution of the pepcase gene family and furthermore that HGTsare a more frequent evolutionary event than previouslythought. PMID:23251445

  6. Hepatic phosphoenolpyruvate carboxykinase expression after gastric bypass surgery in rats with type 2 diabetes mellitus.

    PubMed

    Wu, J; Hou, S S; Wang, W; Yin, M; Cheng, N; Ge, L L; Yin, J J; Xu, J

    2015-01-01

    The objective of this study was to investigate the mRNA expression of hepatic phosphoenolpyruvate carboxykinase (PEPCK) after gastric bypass surgery (GBS) in rats with type 2 diabetic mellitus (T2DM). Thirty-six male Goto-Kakizaki rats, aged 12 weeks, were randomly divided into the GBS, sham operation with diet restriction (SO), and sham operation alone (control) groups (N = 12 per group). Liver specimens from all rats were obtained during the operation and 8 weeks after operation. Blood lipid levels were measured before and 8 weeks after operation. Fasting blood glucose (FBG), food intake, and body weight were recorded at weekly time points after operation. The blood glucose area under the curve (AUC) was calculated, and insulin sensitivity indices (ISI) were assessed. The expression PEPCK mRNA and protein were measured by real-time polymerase chain reaction and western blot. Compared with those of the SO and control groups, the blood lipid levels and the FBG in the GBS group was significantly decreased (P < 0.05), as was the AUC (P < 0.05), whereas the ISI was significantly increased (P < 0.05). PEPCK mRNA and protein levels in the GBS group were lower than those in the control group, whereas those in the SO group were significantly higher than those in controls (P < 0.05). In conclusion, GBS can reduce blood glucose in T2DM rats while improving glucose tolerance and hyperglycemia, and the mechanism appears to be associated with a decrease of hepatic PEPCK mRNA and protein expression. PMID:26681041

  7. Phosphoenolpyruvate Carboxylase in Arabidopsis Leaves Plays a Crucial Role in Carbon and Nitrogen Metabolism1

    PubMed Central

    Shi, Jianghua; Yi, Keke; Liu, Yu; Xie, Li; Zhou, Zhongjing; Chen, Yue; Hu, Zhanghua; Zheng, Tao; Liu, Renhu; Chen, Yunlong; Chen, Jinqing

    2015-01-01

    Phosphoenolpyruvate carboxylase (PEPC) is a crucial enzyme that catalyzes an irreversible primary metabolic reaction in plants. Previous studies have used transgenic plants expressing ectopic PEPC forms with diminished feedback inhibition to examine the role of PEPC in carbon and nitrogen metabolism. To date, the in vivo role of PEPC in carbon and nitrogen metabolism has not been analyzed in plants. In this study, we examined the role of PEPC in plants, demonstrating that PPC1 and PPC2 were highly expressed genes encoding PEPC in Arabidopsis (Arabidopsis thaliana) leaves and that PPC1 and PPC2 accounted for approximately 93% of total PEPC activity in the leaves. A double mutant, ppc1/ppc2, was constructed that exhibited a severe growth-arrest phenotype. The ppc1/ppc2 mutant accumulated more starch and sucrose than wild-type plants when seedlings were grown under normal conditions. Physiological and metabolic analysis revealed that decreased PEPC activity in the ppc1/ppc2 mutant greatly reduced the synthesis of malate and citrate and severely suppressed ammonium assimilation. Furthermore, nitrate levels in the ppc1/ppc2 mutant were significantly lower than those in wild-type plants due to the suppression of ammonium assimilation. Interestingly, starch and sucrose accumulation could be prevented and nitrate levels could be maintained by supplying the ppc1/ppc2 mutant with exogenous malate and glutamate, suggesting that low nitrogen status resulted in the alteration of carbon metabolism and prompted the accumulation of starch and sucrose in the ppc1/ppc2 mutant. Our results demonstrate that PEPC in leaves plays a crucial role in modulating the balance of carbon and nitrogen metabolism in Arabidopsis. PMID:25588735

  8. Key role of hydrazine to the interaction between oxaloacetic against phosphoenolpyruvic carboxykinase (PEPCK): ONIOM calculations.

    PubMed

    Prajongtat, Pongthep; Phromyothin, Darinee Sae-Tang; Hannongbua, Supa

    2013-08-01

    The interactions between oxaloacetic (OAA) and phosphoenolpyruvic carboxykinase (PEPCK) binding pocket in the presence and absence of hydrazine were carried out using quantum chemical calculations, based on the two-layered ONIOM (ONIOM2) approach. The complexes were partially optimized by ONIOM2 (B3LYP/6-31G(d):PM6) method while the interaction energies between OAA and individual residues surrounding the pocket were performed at the MP2/6-31G(d,p) level of theory. The calculated interaction energies (INT) indicated that Arg87, Gly237, Ser286, and Arg405 are key residues for binding to OAA with the INT values of -1.93, -2.06, -2.47, and -3.16 kcal mol(-1), respectively. The interactions are mainly due to the formation of hydrogen bonding interactions with OAA. Moreover, using ONIOM2 (B3LYP/6-31G(d):PM6) applied on the PEPCKHS complex, two proton transfers were observed; first, the proton was transferred from the carboxylic group of OAA to hydrazine while the second one was from Asp311 to Lys244. Such reactions cause the generation of binding strength of OAA to the pocket via electrostatic interaction. The orientations of Lys243, Lys244, His264, Asp311, Phe333, and Arg405 were greatly deviated after hydrazine incorporation. These indicate that hydrazine plays an important role in terms of not only changing the conformation of the binding pocket, but is also tightly bound to OAA resulting in its conformation change in the pocket. The understanding of such interaction can be useful for the design of hydrazine-based inhibitor for antichachexia agents. PMID:23624997

  9. Facilitated diffusion of fructose via the phosphoenolpyruvate/glucose phosphotransferase system of Escherichia coli

    PubMed Central

    Kornberg, Hans L.; Lambourne, Linda T. M.; Sproul, Andrew A.

    2000-01-01

    From mutants of Escherichia coli unable to utilize fructose via the phosphoenolpyruvate/glycose phosphotransferase system (PTS), further mutants were selected that grow on fructose as the sole carbon source, albeit with relatively low affinity for that hexose (Km for growth ≈8 mM but with Vmax for generation time ≈1 h 10 min); the fructose thus taken into the cells is phosphorylated to fructose 6-phosphate by ATP and a cytosolic fructo(manno)kinase (Mak). The gene effecting the translocation of fructose was identified by Hfr-mediated conjugations and by phage-mediated transduction as specifying an isoform of the membrane-spanning enzyme IIGlc of the PTS, which we designate ptsG-F. Exconjugants that had acquired ptsG+ from Hfr strains used for mapping (designated ptsG-I) grew very poorly on fructose (Vmax ≈7 h 20 min), even though they were rich in Mak activity. A mutant of E. coli also rich in Mak but unable to grow on glucose by virtue of transposon-mediated inactivations both of ptsG and of the genes specifying enzyme IIMan (manXYZ) was restored to growth on glucose by plasmids containing either ptsG-F or ptsG-I, but only the former restored growth on fructose. Sequence analysis showed that the difference between these two forms of ptsG, which was reflected also by differences in the rates at which they translocated mannose and glucose analogs such as methyl α-glucoside and 2-deoxyglucose, resided in a substitution of G in ptsG-I by T in ptsG-F in the first position of codon 12, with consequent replacement of valine by phenylalanine in the deduced amino acid sequence. PMID:10677538

  10. Phosphoenolpyruvate carboxykinase, pyruvate orthophosphate dikinase and isocitrate lyase in both tomato fruits and leaves, and in the flesh of peach and some other fruits.

    PubMed

    Famiani, Franco; Paoletti, Andrea; Battistelli, Alberto; Moscatello, Stefano; Chen, Zhi-Hui; Leegood, Richard C; Walker, Robert P

    2016-09-01

    In this study the occurrence of a number of enzymes involved in gluconeogenesis was investigated in both tomato fruits and leaves during their development and senescence and in some other fruits. The enzymes studied were phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK) and glyoxysomal isocitrate lyase (ICL). PPDK was detected in the ripe flesh of tomato, and much smaller amounts were detected in the flesh of both peach and pepper, whereas it was not detected (not present or at very low abundance) in the other fruits which were investigated (apricot, aubergine, blackberry, blueberry, cherry, grape, plum, raspberry and red current). By contrast PEPCK was present in the flesh of all the fruits investigated. Very small amounts of ICL were detected in ripe tomato flesh. PEPCK was present in the skin, flesh, locular gel and columella of tomato fruit, and in these its abundance increased greatly during ripening. PPDK showed a similar distribution, however, its abundance did not increase during ripening. PEPCK was not detected in tomato leaves at any stage of their development or senescence. The content of PPDK g(-1) fresh weight (FW) increased in tomato leaves as they matured, however, it declined during their senescence. In tomato leaves the content of ICL g(-1) FW increased until the mid-stage of development, then decreased as the leaf matured, and then increased during the latter stages of senescence. In the flesh of tomato fruits the contents of PPDK and PEPCK g(-1) FW decreased during senescence. The results suggest that in fruits other than tomato the bulk of any gluconeogenic flux proceeds via PEPCK, whereas in tomato both PEPCK and PPDK could potentially be utilised. Further, the results indicate that the conversion of pyruvate/acetyl-CoA to malate by the glyoxylate cycle, for which ICL is necessary, is not a major pathway utilised by gluconeogenesis in fruits under normal conditions of growth. Finally, the results contribute to

  11. Genetic and Biochemical Characterization of the Phosphoenolpyruvate:Glucose/Mannose Phosphotransferase System of Streptococcus thermophilus

    PubMed Central

    Cochu, Armelle; Vadeboncoeur, Christian; Moineau, Sylvain; Frenette, Michel

    2003-01-01

    In most streptococci, glucose is transported by the phosphoenolpyruvate (PEP):glucose/mannose phosphotransferase system (PTS) via HPr and IIABMan, two proteins involved in regulatory mechanisms. While most strains of Streptococcus thermophilus do not or poorly metabolize glucose, compelling evidence suggests that S. thermophilus possesses the genes that encode the glucose/mannose general and specific PTS proteins. The purposes of this study were to determine (i) whether these PTS genes are expressed, (ii) whether the PTS proteins encoded by these genes are able to transfer a phosphate group from PEP to glucose/mannose PTS substrates, and (iii) whether these proteins catalyze sugar transport. The pts operon is made up of the genes encoding HPr (ptsH) and enzyme I (EI) (ptsI), which are transcribed into a 0.6-kb ptsH mRNA and a 2.3-kb ptsHI mRNA. The specific glucose/mannose PTS proteins, IIABMan, IICMan, IIDMan, and the ManO protein, are encoded by manL, manM, manN, and manO, respectively, which make up the man operon. The man operon is transcribed into a single 3.5-kb mRNA. To assess the phosphotransfer competence of these PTS proteins, in vitro PEP-dependent phosphorylation experiments were conducted with purified HPr, EI, and IIABMan as well as membrane fragments containing IICMan and IIDMan. These PTS components efficiently transferred a phosphate group from PEP to glucose, mannose, 2-deoxyglucose, and (to a lesser extent) fructose, which are common streptococcal glucose/mannose PTS substrates. Whole cells were unable to catalyze the uptake of mannose and 2-deoxyglucose, demonstrating the inability of the S. thermophilus PTS proteins to operate as a proficient transport system. This inability to transport mannose and 2-deoxyglucose may be due to a defective IIC domain. We propose that in S. thermophilus, the general and specific glucose/mannose PTS proteins are not involved in glucose transport but might have regulatory functions associated with the

  12. Hepatic Subcellular Compartmentation of Cytoplasmic Phosphoenolpyruvate Carboxykinase Determined by Immunogold Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Gao, Kuixiong; Cardell, Emma Lou; Morris, Randal E.; Giffin, Bruce F.; Cardell, Robert R.

    1995-08-01

    Phosphoenolpyruvate carboxykinase (PEPCK) is the rate-limiting gluconeogenic enzyme and in liver occurs in a lobular gradient from periportal to pericentral regions. The subcellular distribution of cytoplasmic PEPCK molecules within hepatocytes and its relationship to organelles have not been determined previously. In this study, we have used immunogold electron microscopy to evaluate the subcellar distribution of the enzyme, in addition to brightfield and epipolarized light microscopy. Cryosections (10 [mu]m) of perfusion-fixed rat liver were collected on silanated slides and immunostained using goat anti-rat PEPCK followed by 5-nm gold-labeled secondary and tertiary antibodies. Additionally, free-floating vibratome sections (25, 50, and 100 [mu]m) of perfusion-immersion-fixed rat liver were immunogold stained using goat anti-rat PEPCK and 5-nm gold-labeled secondary antibody, with and without silver enhancement. The immunogold labeled sections from both procedures were embedded in epoxy resin for the preparation of thin sections for electron microscopy. The results showed that the gold-labeled antibodies penetrated the entire thickness of cryosections, resulting in a high signal for PEPCK, but membranes in general, the smooth endoplasmic reticulum in particular, were not identifiable as electron dense unit membranes. On the other hand, the vibratome sections of well-fixed tissue allowed good visualization of the ultrastructure of cellular organelles, with the smooth endoplasmic reticulum appearing as vesicles and tubules with electron dense unit membranes; however, the penetration of the gold-labeled antibody was limited to cells at the surface of the vibratome sections. In both procedures, PEPCK, as indicated by gold particles, is predominantly in the glycogen areas of the cytosome and not in mitochondria, nuclei, Golgi apparatus, or other cell organelles. Hepatocytes in periportal regions have a compact subcellular distribution of PEPCK shown by gold particles

  13. Assessing soybean leaf area and leaf biomass by spectral measurements

    NASA Technical Reports Server (NTRS)

    Holben, B. N.; Tucker, C. J.; Fan, C. J.

    1979-01-01

    Red and photographic infrared spectral radiances were correlated with soybean total leaf area index, green leaf area index, chlorotic leaf area index, green leaf biomass, chlorotic leaf biomass, and total biomass. The most significant correlations were found to exist between the IR/red radiance ratio data and green leaf area index and/or green leaf biomass (r squared equals 0.85 and 0.86, respectively). These findings demonstrate that remote sensing data can supply information basic to soybean canopy growth, development, and status by nondestructive determination of the green leaf area or green leaf biomass.

  14. Activation of SIRT1 by resveratrol represses transcription of the gene for the cytosolic form of phosphoenolpyruvate carboxykinase (GTP) by deacetylating hepatic nuclear factor 4alpha

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cytosolic isoform of phosphoenolpyruvate carboxykinase (GTP) (PEPCK-C) is a key enzyme of gluconeogenesis and glyceroneogenesis. While this enzyme is often over-expressed in diabetes and obesity, studies showed that decrease in its expression results in lessening the diseases condition in animal...

  15. Yellow leaf blotch

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Yellow leaf blotch occurs worldwide in temperate climates. The disease is reported from countries in Asia, Australasia, Oceania, Europe, North America, Central America, the West Indies, and South America. In the northern Great Plains of North America, it is often the major leaf disease on alfalfa....

  16. Phosphoenolpyruvate-dependent phosphorylation of sucrose by Clostridium tyrobutyricum ZJU 8235: evidence for the phosphotransferase transport system.

    PubMed

    Jiang, Ling; Cai, Jin; Wang, Jufang; Liang, Shizhong; Xu, Zhinan; Yang, Shang-Tian

    2010-01-01

    The uptake and metabolism of sucrose, the major sugar in industrial cane molasses, by Clostridium tyrobutyricum ZJU 8235 was investigated and this study provided the first definitive evidence for phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS) activity in butyric acid-producing bacteria. Glucose was utilized preferentially to sucrose when both substrates were present in the medium. The PEP-dependent sucrose: PTS was induced by growing C. tyrobutyricum on sucrose (but not glucose) as the sole carbon source. Extract fractionation and PTS reconstitution experiments revealed that both soluble and membrane components were required for bioactivity. Sucrose-6-phosphate hydrolase and fructokinase activities were also detected in sucrose-grown cultures. Based on these findings, a pathway of sucrose metabolism in this organism was proposed that includes the forming of sucrose-6-phosphate via the PTS and its further degradation into glucose-6-phosphate and fructose-6-phosphate. PMID:19726178

  17. Phosphorylation-dephosphorylation process as a probable mechanism for the diurnal regulatory changes of phosphoenolpyruvate carboxylase in CAM plants.

    PubMed

    Brulfert, J; Vidal, J; Le Marechal, P; Gadal, P; Queiroz, O; Kluge, M; Kruger, I

    1986-04-14

    Day and night forms of phosphoenolpyruvate carboxylase (EC 4.1.1.31) (PEPC) were extracted from leaves of the CAM plants Kalanchoe daigremontiana, K. tubiflora and K. blossfeldiana previously fed with [32P] labelled phosphate solution. A one-step immunochemical purification followed by SDS polyacrylamide gel electrophoresis and autoradiography showed that, in all species, the night form of the enzyme was phosphorylated and not the day form. Limited acid hydrolysis of the night form and two-dimensional separation identified predominantly labelled phosphoserine and phosphothreonine. In vitro addition of exogenous acid phosphatase (EC 3.1.3.2) to desalted night form-containing extracts resulted within 30 min in a shift in PEPC enzymic properties similar to the in vivo changes from night to day form. It is suggested that phosphorylation-dephosphorylation of the enzyme could be the primary in vivo process which might explain the observed rhythmicity of enzymic properties. PMID:3707571

  18. Deletion Mapping of the Genes Coding for HPr and Enzyme I of the Phosphoenolpyruvate: Sugar Phosphotransferase System in Salmonella typhimurium

    PubMed Central

    Cordaro, J. Christopher; Roseman, Saul

    1972-01-01

    Sugars transported by a bacterial phosphoenolpyruvate:sugar phosphotransferase system (PTS) require two soluble proteins: HPr, a low-molecular-weight phosphate-carrier protein, and enzyme I. The structural genes coding for HPr (ptsH) and Enzyme I (ptsI) are shown to be cotransducible in Salmonella typhimurium. The gene order of this region of the Salmonella chromosome is cysA-trzA-ptsH-ptsI...(crr). A method for the isolation of trzA-pts deletion is described. One class of pts deletions extends through ptsH and into ptsI; a second class includes both ptsH and ptsI and extends into or through the crr gene. The crr gene either codes for or regulates the synthesis of a third PTS protein (factor III) which is sugar-specific. A hypothesis is presented for a mechanism of deletion formation. PMID:4562394

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

    PubMed Central

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

    2009-01-01

    SUMMARY 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 PEPCK protein content in the control of gluconeogenesis was unclear. In this study, metabolic control of liver gluconeogenesis was quantified in groups of mice with varying PEPCK protein content. Surprisingly, livers with a 90% reduction in PEPCK content showed only a ~40% reduction in gluconeogenic flux, indicating a lower than expected capacity for PEPCK protein content to control gluconeogenesis. However, PEPCK flux correlated tightly with TCA cycle activity, suggesting that under some conditions in mice, PEPCK expression must coordinate with hepatic energy metabolism to control gluconeogenesis. PMID:17403375

  20. Evolution of the Phosphoenolpyruvate Carboxylase Protein Kinase Family in C3 and C4 Flaveria spp.1[W][OPEN

    PubMed Central

    Aldous, Sophia H.; Weise, Sean E.; Sharkey, Thomas D.; Waldera-Lupa, Daniel M.; Stühler, Kai; Mallmann, Julia; Groth, Georg; Gowik, Udo; Westhoff, Peter; Arsova, Borjana

    2014-01-01

    The key enzyme for C4 photosynthesis, Phosphoenolpyruvate Carboxylase (PEPC), evolved from nonphotosynthetic PEPC found in C3 ancestors. In all plants, PEPC is phosphorylated by Phosphoenolpyruvate Carboxylase Protein Kinase (PPCK). However, differences in the phosphorylation pattern exist among plants with these photosynthetic types, and it is still not clear if they are due to interspecies differences or depend on photosynthetic type. The genus Flaveria contains closely related C3, C3-C4 intermediate, and C4 species, which are evolutionarily young and thus well suited for comparative analysis. To characterize the evolutionary differences in PPCK between plants with C3 and C4 photosynthesis, transcriptome libraries from nine Flaveria spp. were used, and a two-member PPCK family (PPCKA and PPCKB) was identified. Sequence analysis identified a number of C3- and C4-specific residues with various occurrences in the intermediates. Quantitative analysis of transcriptome data revealed that PPCKA and PPCKB exhibit inverse diel expression patterns and that C3 and C4 Flaveria spp. differ in the expression levels of these genes. PPCKA has maximal expression levels during the day, whereas PPCKB has maximal expression during the night. Phosphorylation patterns of PEPC varied among C3 and C4 Flaveria spp. too, with PEPC from the C4 species being predominantly phosphorylated throughout the day, while in the C3 species the phosphorylation level was maintained during the entire 24 h. Since C4 Flaveria spp. evolved from C3 ancestors, this work links the evolutionary changes in sequence, PPCK expression, and phosphorylation pattern to an evolutionary phase shift of kinase activity from a C3 to a C4 mode. PMID:24850859

  1. Leaf growth is conformal.

    PubMed

    Alim, Karen; Armon, Shahaf; Shraiman, Boris I; Boudaoud, Arezki

    2016-01-01

    Growth pattern dynamics lie at the heart of morphogenesis. Here, we investigate the growth of plant leaves. We compute the conformal transformation that maps the contour of a leaf at a given stage onto the contour of the same leaf at a later stage. Based on the mapping we predict the local displacement field in the leaf blade and find it to agree with the experimentally measured displacement field to 92%. This approach is applicable to any two-dimensional system with locally isotropic growth, enabling the deduction of the whole growth field just from observation of the tissue contour. PMID:27597439

  2. Leaf Tissue Senescence

    PubMed Central

    Manos, Peter J.; Goldthwaite, Jonathan

    1975-01-01

    During winter, excised leaf tissue from Rumex obtusifolius degrades chlorophyll at twice the summer rate but the plant hormones, gibberellic acid and zeatin, inhibit the senescence rate by a constant percentage, regardless of season. PMID:16659225

  3. Increased Phosphoenolpyruvate Carboxykinase (PEPCK) Gene Expression and Steatosis During Hepatitis C Virus (HCV) Subgenome Replication: Role of Nonstructural Component-5A (NS5A) and CCAAT/Enhancer Binding Protein ß (C/EBPß)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chronic hepatitis C virus (HCV) infection greatly increases the risk for type 2 diabetes and nonalcoholic steatohepatitis; however, the pathogenic mechanisms remain incompletely understood. Here we report gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) transcription and associated tra...

  4. Deer predation on leaf miners via leaf abscission

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kazuo; Sugiura, Shinji

    2008-03-01

    The evergreen oak Quercus gilva Blume sheds leaves containing mines of the leaf miner Stigmella sp. (Lepidoptera: Nepticulidae) earlier than leaves with no mines in early spring in Nara, central Japan. The eclosion rates of the leaf miner in abscised and retained leaves were compared in the laboratory to clarify the effects of leaf abscission on leaf miner survival in the absence of deer. The leaf miner eclosed successfully from both fallen leaves and leaves retained on trees. However, sika deer ( Cervus nippon centralis Kishida) feed on the fallen mined leaves. Field observations showed that deer consume many fallen leaves under Q. gilva trees, suggesting considerable mortality of leaf miners due to deer predation via leaf abscission. This is a previously unreported relationship between a leaf miner and a mammalian herbivore via leaf abscission.

  5. Damped leaf flexure hinge

    NASA Astrophysics Data System (ADS)

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage.

  6. Damped leaf flexure hinge.

    PubMed

    Chen, Zhong; Chen, Guisheng; Zhang, Xianmin

    2015-05-01

    Flexure-based mechanism like compliant actuation system embeds complex dynamics that will reduce the control bandwidth and limits their dynamic positioning precision. This paper presents a theoretical model of a leaf flexure hinge with damping layers using strain energy method and Kelvin damping model. The modified loss factor of the damped leaf flexure hinge is derived, and the equivalent viscous damping coefficient of the damped leaf hinge is obtained, which could be used to improve the pseudo-rigid-model. The free vibration signals of the hinge in three different damping configurations are measured. The experimental modal analysis also is performed on the three kinds of damped leaf flexure hinges in order to evaluate their 1st order bending natural frequency and vibration-suppressing effects. The evaluation of modified loss factor model also is performed. The experimental results indicate that the constrained layer damping can enhance the structure damping of the hinge even if only single damping layer each side, the modified loss factor model can get good predicts of a damped leaf flexure hinge in the frequency range below 1st order natural frequency, and it is necessary that the dimensional parameters of the damping layers and basic layer of the hinge should be optimized for simplification at the mechanism's design stage. PMID:26026549

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

    PubMed Central

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

    2010-01-01

    In C4 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 C4 dicot Flaveria bidentis grown at a low (LI; 150 μmol quanta m2 s−1) and medium (MI; 500 μmol quanta m2 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 CO2 assimilation per leaf area measured at 1500 μmmol quanta m2 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 CO2 (ϕ) calculated from real-time carbon isotope discrimination was similar for MI and LI plants at high irradiance. ϕ 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 (Sm) and bundle sheath surface area per unit leaf area (Sb) measured from leaf cross-sections were also both significantly greater in MI compared with LI leaves. Both mesophyll and bundle sheath conductance to CO2 diffusion were greater in MI compared with LI plants. Despite being a C4 species, F. bidentis is very plastic with respect to growth irradiance. PMID:20693408

  8. Metabolic analysis of Escherichia coli in the presence and absence of the carboxylating enzymes phosphoenolpyruvate carboxylase and pyruvate carboxylase

    SciTech Connect

    Gokarn, R.R.; Eiteman, M.A.; Altman, E.

    2000-05-01

    Fermentation patterns of Escherichia coli with and without the phosphoenolpyruvate carboxylase (PPC) and pyruvate carboxylase (PYC) enzymes were compared under anaerobic conditions with glucose as a carbon source. Time profiles of glucose and fermentation product concentrations were determined and used to calculate metabolic fluxes through central carbon pathways during exponential cell growth. The presence of the Rhizobium etli pyc gene in E. coli (JCL1242/pTrc99A-pyc) restored the succinate producing ability of E. coli ppc null mutants (JCL1242), with PYC competing favorably with both pyruvate formate lyase and lactate dehydrogenase. Succinate formation was slightly greater by JCL1242/pTrc99a-pyc than by cells which overproduced PPC(JCL1242/pPC201, ppc{sup +}), even though PPC activity in cell extracts of JCL1242/pPC201 (ppc{sup +}) was 40-fold greater than PYC activity in extracts of JCL1242/pTrc99a-pyc. Flux calculations indicate that during anaerobic metabolism the pyc{sup +} strain had a 34% greater specific glucose consumption rate, a 37% greater specific rate of ATP formation, and a 6% greater specific growth rate compared to the ppc{sup +} strain. In light of the important position of pyruvate at the juncture of NADH-generating pathways and NADH-dissimilating branches, the results show that when PPC or PYC is expressed, the metabolic network adapts by altering the flux to lactate and the molar ratio of ethanol to acetate formation.

  9. Reciprocal Changes in Phosphoenolpyruvate Carboxykinase and Pyruvate Kinase with Age Are a Determinant of Aging in Caenorhabditis elegans.

    PubMed

    Yuan, Yiyuan; Hakimi, Parvin; Kao, Clara; Kao, Allison; Liu, Ruifu; Janocha, Allison; Boyd-Tressler, Andrea; Hang, Xi; Alhoraibi, Hanna; Slater, Erin; Xia, Kevin; Cao, Pengxiu; Shue, Quinn; Ching, Tsui-Ting; Hsu, Ao-Lin; Erzurum, Serpil C; Dubyak, George R; Berger, Nathan A; Hanson, Richard W; Feng, Zhaoyang

    2016-01-15

    Aging involves progressive loss of cellular function and integrity, presumably caused by accumulated stochastic damage to cells. Alterations in energy metabolism contribute to aging, but how energy metabolism changes with age, how these changes affect aging, and whether they can be modified to modulate aging remain unclear. In locomotory muscle of post-fertile Caenorhabditis elegans, we identified a progressive decrease in cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), a longevity-associated metabolic enzyme, and a reciprocal increase in glycolytic pyruvate kinase (PK) that were necessary and sufficient to limit lifespan. Decline in PEPCK-C with age also led to loss of cellular function and integrity including muscle activity, and cellular senescence. Genetic and pharmacologic interventions of PEPCK-C, muscle activity, and AMPK signaling demonstrate that declines in PEPCK-C and muscle function with age interacted to limit reproductive life and lifespan via disrupted energy homeostasis. Quantifications of metabolic flux show that reciprocal changes in PEPCK-C and PK with age shunted energy metabolism toward glycolysis, reducing mitochondrial bioenergetics. Last, calorie restriction countered changes in PEPCK-C and PK with age to elicit anti-aging effects via TOR inhibition. Thus, a programmed metabolic event involving PEPCK-C and PK is a determinant of aging that can be modified to modulate aging. PMID:26631730

  10. Phosphoenolpyruvate carboxykinase (PEPCK) deficiency affects the germination, growth and fruit sugar content in tomato (Solanum lycopersicum L.).

    PubMed

    Huang, Yong-Xing; Yin, Yong-Gen; Sanuki, Atsuko; Fukuda, Naoya; Ezura, Hiroshi; Matsukura, Chiaki

    2015-11-01

    Phosphoenolpyruvate carboxykinase (PEPCK) is a key regulatory enzyme and is utilized in the gluconeogenesis pathway in plants. Although, its catalytic and regulatory properties are quite well understood, there are uncertainties regarding its physiological role in many plants tissues such as the flesh of developing fruits. To further understand the function of PEPCK in fruits and other tissues, RNAi transgenic tomato plants in which SlPEPCK transcription was down-regulated by either CaMV 35S constitutive promoter or the fruit-specific E8 promoter were generated and characterized on the basis of their phenotypic and metabolic aspects. In the PEPCK-deficient lines, prominent growth suppression of germinated seedlings was observed and other vegetative suppression appeared during the early stage of plant growth in the 35S promoter-driven lines. In particular, root elongation was most obviously suppressed in the germinated seedlings, indicating that the gluconeogenesis pathway is involved in the root growth of seedlings. Regarding the primary metabolism in fruit, the soluble sugar content tended to decrease, whereas the malate content tended to increase in ripening fruits of the RNAi lines compared with the wild type. These results indicate that activation of the gluconeogenesis pathway from organic acids to sugars occurs during ripening but is suppressed by the knocking down of the PEPCK gene, suggesting that PEPCK participates in determining the sugar/acid ratio in ripening fruit. PMID:26381194

  11. Promotion of photosynthesis in transgenic rice over-expressing of maize C4 phosphoenolpyruvate carboxylase gene by nitric oxide donors.

    PubMed

    Chen, Pingbo; Li, Xia; Huo, Kai; Wei, Xiaodong; Dai, Chuanchao; Lv, Chuangen

    2014-03-15

    We determined the effects of exogenous nitric oxide on photosynthesis and gene expression in transgenic rice plants (PC) over-expressing the maize C4pepc gene, which encodes phosphoenolpyruvate carboxylase (PEPC). Seedlings were subjected to treatments with NO donors, an NO scavenger, phospholipase inhibitors, a Ca(2+) chelator, a Ca(2+) channel inhibitor, and a hydrogen peroxide (H2O2) inhibitor, individually and in various combinations. The NO donors significantly increased the net photosynthetic rate (PN) of PC and wild-type (WT), especially that of PC. Treatment with an NO scavenger did inhibit the PN of rice plants. The treatments with phospholipase inhibitors and a Ca(2+) chelator decreased the PN of WT and PC, and photosynthesis was more strongly inhibited in WT than in PC. Further analyses showed that the NO donors increased endogenous levels of NO and PLD activity, but decreased endogenous levels of Ca(2+) both WT and PC. However, there was a greater increase in NO in WT and a greater increase in PLD activity and Ca(2+) level in PC. The NO donors also increased both PEPC activity and pepc gene expression in PC. PEPC activity can be increased by SNP alone. But the expression of its encoding gene in PC might be regulated by SNP, together with PA and Ca(2+). PMID:24594398

  12. [Activity of NADP-dependent glyceraldehyde-phosphate dehydrogenase and phosphoenolpyruvate carboxylase in wheat leaves under water stress].

    PubMed

    Cherniad'ev, I I; Monakhova, O F

    2006-01-01

    The activities of NADP: glyceraldehyde-phosphate dehydrogenase (GAPDH), an enzyme complex comprising of phosphoglycerate kinase (EC 2.7.2.3) and glyceraldehyde-phosphate dehydrogenase (EC 1.2.1.13), and phosphoenolpyruvate carboxylase (PEPK; EC 4.1.1.31) in seedlings and leaves of wheat (Triticum aestivum L.) plants of the cultivars Mironovskaya 808 and Lutescens 758 have been compared under conditions of normal water supply, water deficiency, and subsequent rehydration. GAPDH activity, which determines the carbohydrate route of photosynthetic metabolism at the initial stages, is decreased by water stress to a greater extent than that of PEPK, on the activity of which non-carbohydrate metabolic pathways depend. Pretreatment of seedlings and mature plants with natural (6-benzylaminopurine) and synthetic (tidiazuron, kartolin-2, and kartolin-4) cytokinins attenuates the loss of enzyme activities during drought and facilitates their recovery within the period of rehydration; both effects are underlain by augmentation of reparation processes. The relative intensification of non-carbohydrate pathways of photosynthetic metabolism, observed under conditions of water deficiency, is accompanied by an increase in the osmotic pressure of cell sap. Possible mechanisms of this protector effect of cytokinin preparations are discussed. PMID:16878554

  13. A Genome-Wide Screen Reveals that the Vibrio cholerae Phosphoenolpyruvate Phosphotransferase System Modulates Virulence Gene Expression

    PubMed Central

    Millet, Yves A.; Chao, Michael C.; Sasabe, Jumpei; Davis, Brigid M.

    2015-01-01

    Diverse environmental stimuli and a complex network of regulatory factors are known to modulate expression of Vibrio cholerae's principal virulence factors. However, there is relatively little known about how metabolic factors impinge upon the pathogen's well-characterized cascade of transcription factors that induce expression of cholera toxin and the toxin-coregulated pilus (TCP). Here, we used a transposon insertion site (TIS) sequencing-based strategy to identify new factors required for expression of tcpA, which encodes the major subunit of TCP, the organism's chief intestinal colonization factor. Besides identifying most of the genes known to modulate tcpA expression, the screen yielded ptsI and ptsH, which encode the enzyme I (EI) and Hpr components of the V. cholerae phosphoenolpyruvate phosphotransferase system (PTS). In addition to reduced expression of TcpA, strains lacking EI, Hpr, or the associated EIIAGlc protein produced less cholera toxin (CT) and had a diminished capacity to colonize the infant mouse intestine. The PTS modulates virulence gene expression by regulating expression of tcpPH and aphAB, which themselves control expression of toxT, the central activator of virulence gene expression. One mechanism by which PTS promotes virulence gene expression appears to be by modulating the amounts of intracellular cyclic AMP (cAMP). Our findings reveal that the V. cholerae PTS is an additional modulator of the ToxT regulon and demonstrate the potency of loss-of-function TIS sequencing screens for defining regulatory networks. PMID:26056384

  14. Transcriptional Gene Silencing Mediated by a Plastid Inner Envelope Phosphoenolpyruvate/Phosphate Translocator CUE1 in Arabidopsis1[OA

    PubMed Central

    Shen, Jie; Ren, Xiaozhi; Cao, Rui; Liu, Jun; Gong, Zhizhong

    2009-01-01

    Mutations in REPRESSOR OF SILENCING1 (ROS1) lead to the transcriptional gene silencing (TGS) of ProRD29A:LUC (LUCIFERASE) and Pro35S:NPTII (Neomycin Phosphotransferase II) reporter genes. We performed a genetic screen to find suppressors of ros1 that identified two mutant alleles in the Arabidopsis (Arabidopsis thaliana) CHLOROPHYLL A/B BINDING PROTEIN UNDEREXPRESSED1 (CUE1) gene, which encodes a plastid inner envelope phosphoenolpyruvate/phosphate translocator. The cue1 mutations released the TGS of Pro35S:NPTII and the transcriptionally silent endogenous locus TRANSCRIPTIONAL SILENCING INFORMATION in a manner that was independent of DNA methylation but dependent on chromatin modification. The cue1 mutations did not affect the TGS of ProRD29A:LUC in ros1, which was dependent on RNA-directed DNA methylation. It is possible that signals from chloroplasts help to regulate the epigenetic status of a subset of genomic loci in the nucleus. PMID:19515789

  15. Cloning and expression of phosphoenolpyruvate carboxykinase from a cestode parasite and its solubilization from inclusion bodies using l-arginine.

    PubMed

    Dutta, Asim K; Ramnath; Dkhar, Barilin; Tandon, Veena; Das, Bidyadhar

    2016-09-01

    Phosphoenolpyruvate carboxykinase is an essential regulatory enzyme of glycolysis in the cestode parasite, Raillietina echinobothrida, and is considered a potential target for anthelmintic action because of its differential activity from that of its avian host. However, due to the unavailability of its structure, the mechanism of regulation of PEPCK from R. echinobothrida (rePEPCK) and its interaction with possible modulators remain unclear. Hence, in this study, the rePEPCK gene was cloned into pGEX-4T-3 and overexpressed for its characterization. On being induced by IPTG, the recombinant rePEPCK was expressed as inclusion bodies (IBs); hence, various agents, like different inducer concentrations, temperature, time, host cell types, culture media, pH, and additives, were used to bring the protein to soluble form. Finally, a significant amount (∼46%) of rePEPCK was solubilized from IBs by adding 2M l-arginine. Near-UV circular dichroism spectra analysis indicated that l-arginine (2M) had no effect on the conformation of the protein. In this study, we have reported a yield of ∼73mg of purified rePEPCK per 1L of culture. The purified rePEPCK retained its biological activity, and Km of the enzyme for its substrate was determined and discussed. The availability of recombinant rePEPCK may help in biochemical- and biophysical-studies to explore its molecular mechanisms and regulations. PMID:26363119

  16. Raspberry leaf curl virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raspberry leaf curl virus (RLCV) is limited to hosts in the genus Rubus and is transmitted persistently by the small raspberry aphid, Aphis rubicola Oestlund. It is found only in North America, principally in the northeastern United States and southeastern Canada and in the Rocky Mountain regions of...

  17. Maple Leaf Outdoor Centre.

    ERIC Educational Resources Information Center

    Maguire, Molly; Gunton, Ric

    2000-01-01

    Maple Leaf Outdoor Centre (Ontario) has added year-round outdoor education facilities and programs to help support its summer camp for disadvantaged children. Schools, youth centers, religious groups, and athletic teams conduct their own programs, collaborate with staff, or use staff-developed programs emphasizing adventure education and personal…

  18. Bacterial leaf spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot has been reported in Australia (Queensland), Egypt, El Salvador, India, Japan, Nicaragua, Sudan, and the United States (Florida, Iowa, Kansas, Maryland, and Wisconsin). It occasionally causes locally severe defoliation and post-emergence damping-off and stunting. The disease is...

  19. Mechanisms of Activation of Phosphoenolpyruvate Carboxykinase from Escherichia coli by Ca2+ and of Desensitization by Trypsin

    PubMed Central

    Sudom, Athena; Walters, Robert; Pastushok, Landon; Goldie, Douglas; Prasad, Lata; Delbaere, Louis T. J.; Goldie, Hughes

    2003-01-01

    The 1.8-Å resolution structure of the ATP-Mg2+-Ca2+-pyruvate quinary complex of Escherichia coli phosphoenolpyruvate carboxykinase (PCK) is isomorphous to the published complex ATP-Mg2+-Mn2+-pyruvate-PCK, except for the Ca2+ and Mn2+ binding sites. Ca2+ was formerly implicated as a possible allosteric regulator of PCK, binding at the active site and at a surface activating site (Glu508 and Glu511). This report found that Ca2+ bound only at the active site, indicating that there is likely no surface allosteric site. 45Ca2+ bound to PCK with a Kd of 85 μM and n of 0.92. Glu508Gln Glu511Gln mutant PCK had normal activation by Ca2+. Separate roles of Mg2+, which binds the nucleotide, and Ca2+, which bridges the nucleotide and the anionic substrate, are implied, and the catalytic mechanism of PCK is better explained by studies of the Ca2+-bound structure. Partial trypsin digestion abolishes Ca2+ activation (desensitizes PCK). N-terminal sequencing identified sensitive sites, i.e., Arg2 and Arg396. Arg2Ser, Arg396Ser, and Arg2Ser Arg396Ser (double mutant) PCKs altered the kinetics of desensitization. C-terminal residues 397 to 540 were removed by trypsin when wild-type PCK was completely desensitized. Phe409 and Phe413 interact with residues in the Ca2+ binding site, probably stabilizing the C terminus. Phe409Ala, ΔPhe409, Phe413Ala, Δ397-521 (deletion of residues 397 to 521), Arg396(TAA) (stop codon), and Asp269Glu (Ca2+ site) mutations failed to desensitize PCK and, with the exception of Phe409Ala, appeared to have defects in the synthesis or assembly of PCK, suggesting that the structure of the C-terminal domain is important in these processes. PMID:12837799

  20. Phosphoenolpyruvate Carboxykinase 1 Gene (Pck1) Displays Parallel Evolution between Old World and New World Fruit Bats

    PubMed Central

    Irwin, David M.; Zhang, Shuyi

    2015-01-01

    Bats are an ideal mammalian group for exploring adaptations to fasting due to their large variety of diets and because fasting is a regular part of their life cycle. Mammals fed on a carbohydrate-rich diet experience a rapid decrease in blood glucose levels during a fast, thus, the development of mechanisms to resist the consequences of regular fasts, experienced on a daily basis, must have been crucial in the evolution of frugivorous bats. Phosphoenolpyruvate carboxykinase 1 (PEPCK1, encoded by the Pck1 gene) is the rate-limiting enzyme in gluconeogenesis and is largely responsible for the maintenance of glucose homeostasis during fasting in fruit-eating bats. To test whether Pck1 has experienced adaptive evolution in frugivorous bats, we obtained Pck1 coding sequence from 20 species of bats, including five Old World fruit bats (OWFBs) (Pteropodidae) and two New World fruit bats (NWFBs) (Phyllostomidae). Our molecular evolutionary analyses of these sequences revealed that Pck1 was under purifying selection in both Old World and New World fruit bats with no evidence of positive selection detected in either ancestral branch leading to fruit bats. Interestingly, however, six specific amino acid substitutions were detected on the ancestral lineage of OWFBs. In addition, we found considerable evidence for parallel evolution, at the amino acid level, between the PEPCK1 sequences of Old World fruit bats and New World fruit bats. Test for parallel evolution showed that four parallel substitutions (Q276R, R503H, I558V and Q593R) were driven by natural selection. Our study provides evidence that Pck1 underwent parallel evolution between Old World and New World fruit bats, two lineages of mammals that feed on a carbohydrate-rich diet and experience regular periods of fasting as part of their life cycle. PMID:25807515

  1. Hepatic nuclear factor 3 is an accessory factor required for the stimulation of phosphoenolpyruvate carboxykinase gene transcription by glucocorticoids.

    PubMed

    Wang, J C; Strömstedt, P E; O'Brien, R M; Granner, D K

    1996-07-01

    Transcription of the hepatic phosphoenolpyruvate carboxykinase gene is stimulated by glucocorticoids and inhibited by insulin. The glucocorticoid response is mediated by a complex glucocorticoid response unit that consists of two glucocorticoid receptor (GR)-binding sites (GR1 and GR2) and two accessory factor-binding sites (AF1 and AF2). The complete unit is required for the full glucocorticoid response. The dominant insulin effect is mediated in part through an insulin response sequence that is coincident with the AF2 element. Members of the hepatic nuclear factor 3 (HNF3) and CCAAT enhancer binding protein (C/EBP) families bind to the AF2 element; however, there is no correlation between binding of these factors and the ability of the AF2 element to mediate an insulin response. We show here that binding of HNF3 does correlate with the stimulation of the glucocorticoid response by the AF2 element and that C/EBP is apparently not involved in this effect. This requirement for HNF3 is quite specific since the substitution of elements known to enhance the action of the GR in other promoters fails to recapitulate AF2 accessory factor activity. By contrast, an HNF3-binding site from the transthyretin gene is able to substitute for the wild type AF2 sequence and elicit a maximal glucocorticoid response. Based on current and previous observations, the glucocorticoid response unit consists of four DNA elements that bind four different proteins. These are: AF1 (hepatic nuclear factor 4/chicken ovalbumin upstream promoter transcription factor), AF2 (HNF3), GR1 (GR), and GR2 (GR). PMID:8813720

  2. The bacterial phosphoenolpyruvate:carbohydrate phosphotransferase system: regulation by protein phosphorylation and phosphorylation-dependent protein-protein interactions.

    PubMed

    Deutscher, Josef; Aké, Francine Moussan Désirée; Derkaoui, Meriem; Zébré, Arthur Constant; Cao, Thanh Nguyen; Bouraoui, Houda; Kentache, Takfarinas; Mokhtari, Abdelhamid; Milohanic, Eliane; Joyet, Philippe

    2014-06-01

    The bacterial phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS) carries out both catalytic and regulatory functions. It catalyzes the transport and phosphorylation of a variety of sugars and sugar derivatives but also carries out numerous regulatory functions related to carbon, nitrogen, and phosphate metabolism, to chemotaxis, to potassium transport, and to the virulence of certain pathogens. For these different regulatory processes, the signal is provided by the phosphorylation state of the PTS components, which varies according to the availability of PTS substrates and the metabolic state of the cell. PEP acts as phosphoryl donor for enzyme I (EI), which, together with HPr and one of several EIIA and EIIB pairs, forms a phosphorylation cascade which allows phosphorylation of the cognate carbohydrate bound to the membrane-spanning EIIC. HPr of firmicutes and numerous proteobacteria is also phosphorylated in an ATP-dependent reaction catalyzed by the bifunctional HPr kinase/phosphorylase. PTS-mediated regulatory mechanisms are based either on direct phosphorylation of the target protein or on phosphorylation-dependent interactions. For regulation by PTS-mediated phosphorylation, the target proteins either acquired a PTS domain by fusing it to their N or C termini or integrated a specific, conserved PTS regulation domain (PRD) or, alternatively, developed their own specific sites for PTS-mediated phosphorylation. Protein-protein interactions can occur with either phosphorylated or unphosphorylated PTS components and can either stimulate or inhibit the function of the target proteins. This large variety of signal transduction mechanisms allows the PTS to regulate numerous proteins and to form a vast regulatory network responding to the phosphorylation state of various PTS components. PMID:24847021

  3. The pepper phosphoenolpyruvate carboxykinase CaPEPCK1 is involved in plant immunity against bacterial and oomycete pathogens.

    PubMed

    Choi, Du Seok; Kim, Nak Hyun; Hwang, Byung Kook

    2015-09-01

    Phosphoenolpyruvate carboxykinase, a member of the lyase family, is involved in the metabolic pathway of gluconeogenesis in organisms. Although the major function of PEPCK in gluconeogenesis is well established, it is unclear whether this enzyme is involved in plant immunity. Here, we isolated and identified the pepper (Capsicum annuum) PEPCK (CaPEPCK1) gene from pepper leaves infected with Xanthomonas campestris pv. vesicatoria (Xcv). CaPEPCK1 was strongly expressed in pepper leaves during the incompatible interaction with avirulent Xcv and in response to environmental stresses, especially salicylic acid (SA) treatment. PEPCK activity was low in healthy leaves but dramatically increased in avirulent Xcv-infected leaves. Knock-down expression of CaPEPCK1 by virus-induced gene silencing resulted in high levels of susceptibility to both virulent and avirulent Xcv infection. CaPEPCK1 silencing in pepper compromised induction of the basal defense-marker genes CaPR1 (pathogenesis-related 1 protein), CaPR10 (pathogenesis-related 10 protein) and CaDEF1 (defensin) during Xcv infection. SA accumulation was also significantly suppressed in the CaPEPCK1-silenced pepper leaves infected with Xcv. CaPEPCK1 in an Arabidopsis overexpression (OX) line inhibited the proliferation of Pseudomonas syringae pv. tomato (Pst) and Hyaloperonospora arabidopsidis (Hpa). CaPEPCK1-OX plants developed more rapidly, with enlarged leaves, compared to wild-type plants. The T-DNA insertion Arabidopsis orthologous mutants pck1-3 and pck1-4 were more susceptible to the bacterial Pst and oomycete Hpa pathogens than the wild type. Taken together, these results suggest that CaPEPCK positively contributes to plant innate immunity against hemibiotrophic bacterial and obligate biotrophic oomycete pathogens. PMID:26233534

  4. Positive selection of Kranz and non-Kranz C4 phosphoenolpyruvate carboxylase amino acids in Suaedoideae (Chenopodiaceae)

    PubMed Central

    Rosnow, Josh J.; Edwards, Gerald E.; Roalson, Eric H.

    2014-01-01

    In subfamily Suaedoideae, four independent gains of C4 photosynthesis are proposed, which includes two parallel origins of Kranz anatomy (sections Salsina and Schoberia) and two independent origins of single-cell C4 anatomy (Bienertia and Suaeda aralocaspica). Additional phylogenetic support for this hypothesis was generated from sequence data of the C-terminal portion of the phosphoenolpyruvate carboxylase (PEPC) gene used in C4 photosynthesis (ppc-1) in combination with previous sequence data. ppc-1 sequence was generated for 20 species in Suaedoideae and two outgroup Salsola species that included all types of C4 anatomies as well as two types of C3 anatomies. A branch-site test for positively selected codons was performed using the software package PAML. From labelling of the four branches where C4 is hypothesized to have developed (foreground branches), residue 733 (maize numbering) was identified to be under positive selection with a posterior probability >0.99 and residue 868 at the >0.95 interval using Bayes empirical Bayes (BEB). When labelling all the branches within C4 clades, the branch-site test identified 13 codons to be under selection with a posterior probability >0.95 by BEB; this is discussed considering current information on functional residues. The signature C4 substitution of an alanine for a serine at position 780 in the C-terminal end (which is considered a major determinant of affinity for PEP) was only found in four of the C4 species sampled, while eight of the C4 species and all the C3 species have an alanine residue; indicating that this substitution is not a requirement for C4 function. PMID:24600021

  5. The Bacterial Phosphoenolpyruvate:Carbohydrate Phosphotransferase System: Regulation by Protein Phosphorylation and Phosphorylation-Dependent Protein-Protein Interactions

    PubMed Central

    Aké, Francine Moussan Désirée; Derkaoui, Meriem; Zébré, Arthur Constant; Cao, Thanh Nguyen; Bouraoui, Houda; Kentache, Takfarinas; Mokhtari, Abdelhamid; Milohanic, Eliane; Joyet, Philippe

    2014-01-01

    SUMMARY The bacterial phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS) carries out both catalytic and regulatory functions. It catalyzes the transport and phosphorylation of a variety of sugars and sugar derivatives but also carries out numerous regulatory functions related to carbon, nitrogen, and phosphate metabolism, to chemotaxis, to potassium transport, and to the virulence of certain pathogens. For these different regulatory processes, the signal is provided by the phosphorylation state of the PTS components, which varies according to the availability of PTS substrates and the metabolic state of the cell. PEP acts as phosphoryl donor for enzyme I (EI), which, together with HPr and one of several EIIA and EIIB pairs, forms a phosphorylation cascade which allows phosphorylation of the cognate carbohydrate bound to the membrane-spanning EIIC. HPr of firmicutes and numerous proteobacteria is also phosphorylated in an ATP-dependent reaction catalyzed by the bifunctional HPr kinase/phosphorylase. PTS-mediated regulatory mechanisms are based either on direct phosphorylation of the target protein or on phosphorylation-dependent interactions. For regulation by PTS-mediated phosphorylation, the target proteins either acquired a PTS domain by fusing it to their N or C termini or integrated a specific, conserved PTS regulation domain (PRD) or, alternatively, developed their own specific sites for PTS-mediated phosphorylation. Protein-protein interactions can occur with either phosphorylated or unphosphorylated PTS components and can either stimulate or inhibit the function of the target proteins. This large variety of signal transduction mechanisms allows the PTS to regulate numerous proteins and to form a vast regulatory network responding to the phosphorylation state of various PTS components. PMID:24847021

  6. Identification of tumor necrosis factor as a transcriptional regulator of the phosphoenolpyruvate carboxykinase gene following endotoxin treatment of mice.

    PubMed Central

    Hill, M R; McCallum, R E

    1992-01-01

    The decreased synthesis of hepatic phosphoenolpyruvate carboxykinase (PEPCK), the rate-limiting enzyme of gluconeogenesis, that occurs during endotoxemia was shown previously in rats to occur at the transcriptional level. In the current study, the exogenous administration of human recombinant tumor necrosis factor (TNF), a proximal mediator of endotoxic shock, reduced the PEPCK transcription rate, mRNAPEPCK levels, and PEPCK enzyme activity in a time- and dose-dependent manner in CD-1 mice. Comparable amounts of circulating TNF were measured in mice 2 h after injection of human recombinant TNF (10(5) U) or a 50% lethal dose of Escherichia coli endotoxin (20 mg/kg). Direct action of TNF to decrease the PEPCK transcription rate was confirmed in vitro with H-4-II-E Reuber hepatoma cells, in which a dose-dependent inhibition of PEPCK transcription was observed with 1 to 100 U of TNF per ml. A role for TNF-elicited changes in PEPCK gene expression during endotoxemia was confirmed by the protective effect of rabbit polyclonal antibodies to recombinant murine TNF. C57BL/6 mice passively immunized with anti-TNF 4 h prior to endotoxin challenge exhibited normal PEPCK enzyme activity. Neutralization of circulating TNF with anti-TNF failed, however, to prevent the hypoglycemia commonly observed during endotoxemia, suggesting the participation of other mediators. Anti-TNF treatment reduced circulating interleukins 1 and 6 at 3 and 6 h after endotoxin treatment, respectively. These results suggest that during endotoxemia, the development of hypoglycemia is multifaceted and that several cytokines are most likely involved. The findings from the Reuber hepatoma cell model afford an opportunity in future work to map putative cytokine response elements in the PEPCK promoter responsible for perturbed hormonal regulation of the gene during endotoxemia. PMID:1398916

  7. Co-expression of phosphoenolpyruvate carboxykinase and nicotinic acid phosphoribosyltransferase for succinate production in engineered Escherichia coli.

    PubMed

    Jiang, Min; Chen, Xu; Liang, Liya; Liu, Rongming; Wan, Qing; Wu, Mingke; Zhang, Hanwen; Ma, Jiangfeng; Chen, Kequan; Ouyang, Pingkai

    2014-03-01

    Succinate is not the dominant fermentation product from xylose in wild-type Escherichia coli K12. E. coli BA 203 is a lactate dehydrogenase (ldhA), pyruvate formate lyase (pflB), and phosphoenolpyruvate (PEP)-carboxylase (ppc) deletion strain. To increase succinate accumulation and reduce byproduct formation, engineered E. coli BA204, in which ATP-forming PEP-carboxykinase (PEPCK) is overexpressed in BA203, was constructed and produced 2.17-fold higher succinate yield. To further improve the biomass and the consumption rate of xylose, nicotinic acid phosphoribosyltransferase (NAPRTase), a rate limiting enzyme in the synthesis of NAD(H), was also overexpressed. Thus, co-expression of PEPCK and NAPRTase in recombinant E. coli BA209 was investigated. In BA209, the pck gene and the pncB gene each have a trc promoter, hence, both genes are well expressed. During a 72-h anaerobic fermentation in sealed bottles, the total concentration of NAD(H) in BA209 was 1.25-fold higher than that in BA204, and the NADH/NAD+ ratio decreased from 0.28 to 0.11. During the exclusively anaerobic fermentation in a 3-L bioreactor, BA209 consumed 17.1 g L⁻¹ xylose and produced 15.5 g L⁻¹ succinate. Furthermore, anaerobic fermentation of corn stalk hydrolysate contained 30.1 g L⁻¹ xylose, 2.1 g L⁻¹ glucose and 1.5 g L⁻¹ arabinose, it produced a final succinate concentration of 17.2 g L⁻¹ with a yield of 0.94 g g⁻¹ total sugars. PMID:24564896

  8. Phosphoenolpyruvate carboxykinase 1 gene (Pck1) displays parallel evolution between Old World and New World fruit bats.

    PubMed

    Zhu, Lei; Yin, Qiuyuan; Irwin, David M; Zhang, Shuyi

    2015-01-01

    Bats are an ideal mammalian group for exploring adaptations to fasting due to their large variety of diets and because fasting is a regular part of their life cycle. Mammals fed on a carbohydrate-rich diet experience a rapid decrease in blood glucose levels during a fast, thus, the development of mechanisms to resist the consequences of regular fasts, experienced on a daily basis, must have been crucial in the evolution of frugivorous bats. Phosphoenolpyruvate carboxykinase 1 (PEPCK1, encoded by the Pck1 gene) is the rate-limiting enzyme in gluconeogenesis and is largely responsible for the maintenance of glucose homeostasis during fasting in fruit-eating bats. To test whether Pck1 has experienced adaptive evolution in frugivorous bats, we obtained Pck1 coding sequence from 20 species of bats, including five Old World fruit bats (OWFBs) (Pteropodidae) and two New World fruit bats (NWFBs) (Phyllostomidae). Our molecular evolutionary analyses of these sequences revealed that Pck1 was under purifying selection in both Old World and New World fruit bats with no evidence of positive selection detected in either ancestral branch leading to fruit bats. Interestingly, however, six specific amino acid substitutions were detected on the ancestral lineage of OWFBs. In addition, we found considerable evidence for parallel evolution, at the amino acid level, between the PEPCK1 sequences of Old World fruit bats and New World fruit bats. Test for parallel evolution showed that four parallel substitutions (Q276R, R503H, I558V and Q593R) were driven by natural selection. Our study provides evidence that Pck1 underwent parallel evolution between Old World and New World fruit bats, two lineages of mammals that feed on a carbohydrate-rich diet and experience regular periods of fasting as part of their life cycle. PMID:25807515

  9. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  10. Comparative Analysis of the Escherichia coli Ketopantoate Hydroxymethyltransferase Crystal Structure Confirms that It Is a Member of the (βα)8 Phosphoenolpyruvate/Pyruvate Superfamily

    PubMed Central

    Schmitzberger, Florian; Smith, Alison G.; Abell, Chris; Blundell, Tom L.

    2003-01-01

    Escherichia coli ketopantoate hydroxymethyltransferase (KPHMT) catalyzes the first step in the biosynthesis pathway of pantothenate (vitamin B5), the transfer of a hydroxymethyl group onto α-ketoisovalerate. Here we describe a detailed comparative analysis of the KPHMT crystal structure and the identification of structural homologues, some of which have remarkable similarities in their active sites, modes of binding to substrates, and mechanisms. We show that KPHMT forms a family within the phosphoenolpyruvate/pyruvate superfamily. Based on the analysis, we propose that in this superfamily there should be a subdivision into two groups. This paper completes our structural analysis of the E. coli enzymes in the pantothenate pathway. PMID:12837791

  11. Leaf development: a cellular perspective

    PubMed Central

    Kalve, Shweta; De Vos, Dirk; Beemster, Gerrit T. S.

    2014-01-01

    Through its photosynthetic capacity the leaf provides the basis for growth of the whole plant. In order to improve crops for higher productivity and resistance for future climate scenarios, it is important to obtain a mechanistic understanding of leaf growth and development and the effect of genetic and environmental factors on the process. Cells are both the basic building blocks of the leaf and the regulatory units that integrate genetic and environmental information into the developmental program. Therefore, to fundamentally understand leaf development, one needs to be able to reconstruct the developmental pathway of individual cells (and their progeny) from the stem cell niche to their final position in the mature leaf. To build the basis for such understanding, we review current knowledge on the spatial and temporal regulation mechanisms operating on cells, contributing to the formation of a leaf. We focus on the molecular networks that control exit from stem cell fate, leaf initiation, polarity, cytoplasmic growth, cell division, endoreduplication, transition between division and expansion, expansion and differentiation and their regulation by intercellular signaling molecules, including plant hormones, sugars, peptides, proteins, and microRNAs. We discuss to what extent the knowledge available in the literature is suitable to be applied in systems biology approaches to model the process of leaf growth, in order to better understand and predict leaf growth starting with the model species Arabidopsis thaliana. PMID:25132838

  12. Synthesis of HPr(Ser-P)(His-P) by enzyme I of the phosphoenolpyruvate: sugar phosphotransferase system of Streptococcus salivarius.

    PubMed

    Casabon, Israël; Couture, Manon; Vaillancourt, Katy; Vadeboncoeur, Christian

    2006-05-30

    HPr is a protein of the bacterial phosphoenolpyruvate:sugar phosphotransferase transport system (PTS). In Gram-positive bacteria, HPr can be phosphorylated on Ser(46) by HPr(Ser) kinase/phosphorylase (HPrK/P) and on His(15) by enzyme I (EI) of the PTS. In vitro studies have shown that phosphorylation on one residue greatly inhibits the second phosphorylation. However, streptococci contain significant amounts of HPr(Ser-P)(His approximately P) during exponential growth, and recent studies suggest that phosphorylation of HPr(Ser-P) by EI is involved in the recycling of HPr(Ser-P)(His approximately P). We report in this paper a study on the phosphorylation of Streptococcus salivarius HPr, HPr(Ser-P), and HPr(S46D) by EI. Our results indicate that (i) the specificity constant (k(cat)/K(m)) of EI for HPr(Ser-P) at pH 7.9 was approximately 5000-fold smaller than that observed for HPr, (ii) no metabolic intermediates were able to stimulate HPr(Ser-P) phosphorylation, (iii) the rate of HPr phosphorylation decreased at pHs below 6.5, while that of HPr(Ser-P) increased and was almost 10-fold higher at pH 6.1 than at pH 7.9, (iv) HPr(S46D), a mutated HPr alleged to mimic HPr(Ser-P), was also phosphorylated more efficiently under acidic conditions, and, lastly, (v) phosphorylation of Bacillus subtilis HPr(Ser-P) by B. subtilis EI was also stimulated at acidic pH. Our results suggest that the high levels of HPr(Ser-P)(His approximately P) in streptococci result from the combination of two factors, a high physiological concentration of HPr(Ser-P) and stimulation of HPr(Ser-P) phosphorylation by EI at acidic pH, an intracellular condition that occurs in response to the acidification of the external medium during growth of the culture. PMID:16716080

  13. Physiological and Transcriptional Characterization of Escherichia Coli Strains Lacking Interconversion of Phosphoenolpyruvate and Pyruvate When Glucose and Acetate are Coutilized

    PubMed Central

    Sabido, Andrea; Sigala, Juan Carlos; Hernández-Chávez, Georgina; Flores, Noemí; Gosset, Guillermo; Bolívar, Francisco

    2013-01-01

    Phosphoenolpyruvate (PEP) is a precursor involved in the biosynthesis of aromatics and other valuable compounds in Escherichia coli. The PEP:carbohydrate phosphotransferase system (PTS) is the major glucose transport system and the largest PEP consumer. To increase intracellular PEP availability for aromatics production purposes, mutant strains of E. coli JM101 devoid of the ptsHIcrr operon (PB11 strain) have been previously generated. In this derivative, transport and growth rate on glucose decreased significantly. A laboratory evolved strain derived from PB11 that partially recovered its growth capacity on glucose was named PB12. In the present study, we blocked carbon skeletons interchange between PEP and pyruvate (PYR) in these ptsHIcrr− strains by deleting the pykA, pykF, and ppsA genes. The PB11 pykAF− ppsA− strain exhibited no growth on glucose or acetate alone, but it was viable when both substrates were consumed simultaneously. In contrast, the PB12 pykAF− ppsA− strain displayed a low growth rate on glucose or acetate alone, but in the mixture, growth was significantly improved. RT-qPCR expression analysis of PB11 pykAF− ppsA− growing with both carbon sources showed a downregulation of all central metabolic pathways compared with its parental PB11 strain. Under the same conditions, transcription of most of the genes in PB12 pykAF− ppsA− did not change, and few like aceBAK, sfcA, and poxB were overexpressed compared with PB12. We explored the aromatics production capabilities of both ptsHIcrr− pykAF− ppsA− strains and the engineered PB12 pykAF− ppsA− tyrR− pheAev2+/pJLBaroGfbrtktA enhanced the yield of aromatic compounds when coutilizing glucose and acetate compared with the control strain PB12 tyrR− pheAev2+/pJLBaroGfbrtktA. Biotechnol. Bioeng. 2014;111: 1150–1160. © 2013 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:24375081

  14. Insight into the mechanism of phosphoenolpyruvate mutase catalysis derived from site-directed mutagenesis studies of active site residues.

    PubMed

    Jia, Y; Lu, Z; Huang, K; Herzberg, O; Dunaway-Mariano, D

    1999-10-26

    PEP mutase catalyzes the conversion of phosphoenolpyruvate (PEP) to phosphonopyruvate in biosynthetic pathways leading to phosphonate secondary metabolites. A recent X-ray structure [Huang, K., Li, Z., Jia, Y., Dunaway-Mariano, D., and Herzberg, O. (1999) Structure (in press)] of the Mytilus edulis enzyme complexed with the Mg(II) cofactor and oxalate inhibitor reveals an alpha/beta-barrel backbone-fold housing an active site in which Mg(II) is bound by the two carboxylate groups of the oxalate ligand and the side chain of D85 and, via bridging water molecules, by the side chains of D58, D85, D87, and E114. The oxalate ligand, in turn, interacts with the side chains of R159, W44, and S46 and the backbone amide NHs of G47 and L48. Modeling studies identified two feasible PEP binding modes: model A in which PEP replaces oxalate with its carboxylate group interacting with R159 and its phosphoryl group positioned close to D58 and Mg(II) shifting slightly from its original position in the crystal structure, and model B in which PEP replaces oxalate with its phosphoryl group interacting with R159 and Mg(II) retaining its original position. Site-directed mutagenesis studies of the key mutase active site residues (R159, D58, D85, D87, and E114) were carried out in order to evaluate the catalytic roles predicted by the two models. The observed retention of low catalytic activity in the mutants R159A, D85A, D87A, and E114A, coupled with the absence of detectable catalytic activity in D58A, was interpreted as evidence for model A in which D58 functions in nucleophilic catalysis (phosphoryl transfer), R159 functions in PEP carboxylate group binding, and the carboxylates of D85, D87 and E114 function in Mg(II) binding. These results also provide evidence against model B in which R159 serves to mediate the phosphoryl transfer. A catalytic motif, which could serve both the phosphoryl transfer and the C-C cleavage enzymes of the PEP mutase superfamily, is proposed. PMID:10571990

  15. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture...

  16. On the mechanism of phosphoenolpyruvate synthetase (PEPs) and its inhibition by sodium fluoride: potential magnesium and aluminum fluoride complexes of phosphoryl transfer.

    PubMed

    McCormick, Nicole E; Jakeman, David L

    2015-06-01

    Phosphoenolpyruvate synthase (PEPs) catalyzes the conversion of pyruvate to phosphoenolpyruvate (PEP) using a two-step mechanism invoking a phosphorylated-His intermediate. Formation of PEP is an initial step in gluconeogenesis, and PEPs is essential for growth of Escherichia coli on 3-carbon sources such as pyruvate. The production of PEPs has also been linked to bacterial virulence and antibiotic resistance. As such, PEPs is of interest as a target for antibiotic development, and initial investigations of PEPs have indicated inhibition by sodium fluoride. Similar inhibition has been observed in a variety of phospho-transfer enzymes through the formation of metal fluoride complexes within the active site. Herein we quantify the inhibitory capacity of sodium fluoride through a coupled spectrophotometric assay. The observed inhibition provides indirect evidence for the formation of a MgF3(-) complex within the enzyme active site and insight into the phospho-transfer mechanism of PEPs. The effect of AlCl3 on PEPs enzyme activity was also assessed and found to decrease substrate binding and turnover. PMID:25707819

  17. The artificial leaf.

    PubMed

    Nocera, Daniel G

    2012-05-15

    To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron-hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin-NADP(+) reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 sun (100 mW/cm(2)) illumination. This Account describes the construction of an artificial leaf comprising earth-abundant elements by interfacing a triple junction, amorphous silicon photovoltaic with hydrogen- and oxygen-evolving catalysts made from a ternary alloy (NiMoZn) and a cobalt-phosphate cluster (Co-OEC), respectively. The latter captures the structural and functional attributes of the PSII-OEC. Similar to the PSII-OEC, the Co-OEC self-assembles upon oxidation of an earth-abundant metal ion from 2+ to 3+, may operate in natural water at room temperature, and is self-healing. The Co-OEC also activates H(2)O by a proton-coupled electron transfer mechanism in which the Co-OEC is increased by four hole equivalents akin to the S-state pumping of the Kok cycle of PSII. X-ray absorption spectroscopy studies have established that the Co-OEC is a structural relative of Mn(3)CaO(4)-Mn cubane of the PSII-OEC, where Co replaces Mn and the cubane is extended in a

  18. Integration of Lupinus angustifolius L. (narrow-leafed lupin) genome maps and comparative mapping within legumes.

    PubMed

    Wyrwa, Katarzyna; Książkiewicz, Michał; Szczepaniak, Anna; Susek, Karolina; Podkowiński, Jan; Naganowska, Barbara

    2016-09-01

    Narrow-leafed lupin (Lupinus angustifolius L.) has recently been considered a reference genome for the Lupinus genus. In the present work, genetic and cytogenetic maps of L. angustifolius were supplemented with 30 new molecular markers representing lupin genome regions, harboring genes involved in nitrogen fixation during the symbiotic interaction of legumes and soil bacteria (Rhizobiaceae). Our studies resulted in the precise localization of bacterial artificial chromosomes (BACs) carrying sequence variants for early nodulin 40, nodulin 26, nodulin 45, aspartate aminotransferase P2, asparagine synthetase, cytosolic glutamine synthetase, and phosphoenolpyruvate carboxylase. Together with previously mapped chromosomes, the integrated L. angustifolius map encompasses 73 chromosome markers, including 5S ribosomal DNA (rDNA) and 45S rDNA, and anchors 20 L. angustifolius linkage groups to corresponding chromosomes. Chromosomal identification using BAC fluorescence in situ hybridization identified two BAC clones as narrow-leafed lupin centromere-specific markers, which served as templates for preliminary studies of centromere composition within the genus. Bioinformatic analysis of these two BACs revealed that centromeric/pericentromeric regions of narrow-leafed lupin chromosomes consisted of simple sequence repeats ordered into tandem repeats containing the trinucleotide and pentanucleotide simple sequence repeats AGG and GATAC, structured into long arrays. Moreover, cross-genus microsynteny analysis revealed syntenic patterns of 31 single-locus BAC clones among several legume species. The gene and chromosome level findings provide evidence of ancient duplication events that must have occurred very early in the divergence of papilionoid lineages. This work provides a strong foundation for future comparative mapping among legumes and may facilitate understanding of mechanisms involved in shaping legume chromosomes. PMID:27168155

  19. Exserohilum Leaf Spot on Tigergrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tigergrass (Thysanolaena maxima (Roxb.) Kuntze ) is a popular ornamental grass grown throughout landscapes in South Florida. In the summer of 2006, a leaf spot was observed on tigergrass in the landscape and a commercial nursery in Homestead, FL. The causal agent of the leaf spot was isolated, cha...

  20. How to pattern a leaf

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf development presents a tremendous resource for tackling the question of patterning in biology. Leaves can be simple or highly dissected. They may have elaborated parts such as the tendrils of a pea leaf or the rolled blade of a carnivorous pitcher plant. Despite the variation in size, shape, an...

  1. Leaf hydraulics II: vascularized tissues.

    PubMed

    Rockwell, Fulton E; Holbrook, N Michele; Stroock, Abraham D

    2014-01-01

    Current models of leaf hydration employ an Ohm's law analogy of the leaf as an ideal capacitor, neglecting the resistance to flow between cells, or treat the leaf as a plane sheet with a source of water at fixed potential filling the mid-plane, neglecting the discrete placement of veins as well as their resistance. We develop a model of leaf hydration that considers the average conductance of the vascular network to a representative areole (region bounded by the vascular network), and represent the volume of tissue within the areole as a poroelastic composite of cells and air spaces. Solutions to the 3D flow problem are found by numerical simulation, and these results are then compared to 1D models with exact solutions for a range of leaf geometries, based on a survey of temperate woody plants. We then show that the hydration times given by these solutions are well approximated by a sum of the ideal capacitor and plane sheet times, representing the time for transport through the vasculature and tissue respectively. We then develop scaling factors relating this approximate solution to the 3D model, and examine the dependence of these scaling factors on leaf geometry. Finally, we apply a similar strategy to reduce the dimensions of the steady state problem, in the context of peristomatal transpiration, and consider the relation of transpirational gradients to equilibrium leaf water potential measurements. PMID:24012489

  2. Leaf Relative Water Content Estimated from Leaf Reflectance and Transmittance

    NASA Technical Reports Server (NTRS)

    Vanderbilt, Vern; Daughtry, Craig; Dahlgren, Robert

    2016-01-01

    Remotely sensing the water status of plants and the water content of canopies remain long term goals of remote sensing research. In the research we report here, we used optical polarization techniques to monitor the light reflected from the leaf interior, R, as well as the leaf transmittance, T, as the relative water content (RWC) of corn (Zea mays) leaves decreased. Our results show that R and T both change nonlinearly. The result show that the nonlinearities cancel in the ratio R/T, which appears linearly related to RWC for RWC less than 90%. The results suggest that potentially leaf water status and perhaps even canopy water status could be monitored starting from leaf and canopy optical measurements.

  3. Regulation of Compound Leaf Development

    PubMed Central

    Wang, Yuan; Chen, Rujin

    2013-01-01

    Leaf morphology is one of the most variable, yet inheritable, traits in the plant kingdom. How plants develop a variety of forms and shapes is a major biological question. Here, we discuss some recent progress in understanding the development of compound or dissected leaves in model species, such as tomato (Solanum lycopersicum), Cardamine hirsuta and Medicago truncatula, with an emphasis on recent discoveries in legumes. We also discuss progress in gene regulations and hormonal actions in compound leaf development. These studies facilitate our understanding of the underlying regulatory mechanisms and put forward a prospective in compound leaf studies. PMID:27135488

  4. Differentiation of C4 photosynthesis along a leaf developmental gradient in two Cleome species having different forms of Kranz anatomy.

    PubMed

    Koteyeva, Nuria K; Voznesenskaya, Elena V; Cousins, Asaph B; Edwards, Gerald E

    2014-07-01

    In family Cleomaceae there are NAD-malic enzyme-type C4 species having different forms of leaf anatomy. Leaves of Cleome angustifolia have Glossocardioid-type anatomy with a single complex Kranz unit which surrounds all the veins, while C. gynandra has Atriplicoid anatomy with multiple Kranz units, each surrounding an individual vein. Biochemical and ultrastructural differentiation of mesophyll (M) and bundle sheath (BS) cells were studied along a developmental gradient, from the leaf base (youngest) to the tip (mature). Initially, there is cell-specific expression of certain photosynthetic enzymes, which subsequently increase along with structural differentiation. At the base of the leaf, following division of ground tissue to form M and BS cells which are structurally similar, there is selective localization of Rubisco and glycine decarboxylase to BS cells. Thus, a biochemical C3 default stage, with Rubisco expression in both cell types, does not occur. Additionally, phosphoenolpyruvate carboxylase (PEPC) is selectively expressed in M cells near the base. Surprisingly, in both species, an additional layer of spongy M cells on the abaxial side of the leaf has the same differentiation with PEPC, even though it is not in contact with BS cells. During development along the longitudinal gradient there is structural differentiation of the cells, chloroplasts, and mitochondria, resulting in complete formation of Kranz anatomy. In both species, development of the C4 system occurs similarly, irrespective of having very different types of Kranz anatomy, different ontogenetic origins of BS and M, and independent evolutionary origins of C4 photosynthesis. PMID:24550438

  5. Differentiation of C4 photosynthesis along a leaf developmental gradient in two Cleome species having different forms of Kranz anatomy

    PubMed Central

    Koteyeva, Nuria K.; Voznesenskaya, Elena V.; Cousins, Asaph B.; Edwards, Gerald E.

    2014-01-01

    In family Cleomaceae there are NAD-malic enzyme-type C4 species having different forms of leaf anatomy. Leaves of Cleome angustifolia have Glossocardioid-type anatomy with a single complex Kranz unit which surrounds all the veins, while C. gynandra has Atriplicoid anatomy with multiple Kranz units, each surrounding an individual vein. Biochemical and ultrastructural differentiation of mesophyll (M) and bundle sheath (BS) cells were studied along a developmental gradient, from the leaf base (youngest) to the tip (mature). Initially, there is cell-specific expression of certain photosynthetic enzymes, which subsequently increase along with structural differentiation. At the base of the leaf, following division of ground tissue to form M and BS cells which are structurally similar, there is selective localization of Rubisco and glycine decarboxylase to BS cells. Thus, a biochemical C3 default stage, with Rubisco expression in both cell types, does not occur. Additionally, phosphoenolpyruvate carboxylase (PEPC) is selectively expressed in M cells near the base. Surprisingly, in both species, an additional layer of spongy M cells on the abaxial side of the leaf has the same differentiation with PEPC, even though it is not in contact with BS cells. During development along the longitudinal gradient there is structural differentiation of the cells, chloroplasts, and mitochondria, resulting in complete formation of Kranz anatomy. In both species, development of the C4 system occurs similarly, irrespective of having very different types of Kranz anatomy, different ontogenetic origins of BS and M, and independent evolutionary origins of C4 photosynthesis. PMID:24550438

  6. 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.

    PubMed

    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. PMID:24276159

  7. Cloning, expression, purification and physical and kinetic characterization of the phosphoenolpyruvate carboxylase from orange (Citrus sinensis osbeck var. Valencia) fruit juice sacs.

    PubMed

    Perotti, Valeria E; Figueroa, Carlos M; Andreo, Carlos S; Iglesias, Alberto A; Podestá, Florencio E

    2010-11-01

    Phosphoenolpyruvate (PEP) carboxylase (PEPCase) from orange fruit juice sacs has been cloned and heterogously expressed in high yield. The purified recombinant enzyme displays properties typical of plant PEPCase, including activation by sugar phosphates and inhibition by malate and citrate. Malate inhibition is weak in the physiological pH range, and the enzyme is also poorly affected by Glu and Asp, known inhibitors of C(3) plants PEPCases. However, it is strongly inhibited by citrate. Orange fruit PEPCase phosphorylation by mammalian protein kinase A decreased inhibition by malate. The enzyme presents an unusual high molecular mass in the absence of PEP, while in its presence it displays a more common tetrameric arrangement. The overall properties of the enzyme suggest that it is suited for organic acid synthesis and NADH reoxidation in the mature fruit. The present study provides the first analysis of a recombinant fruit PEPCase. PMID:21802611

  8. Mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) is a pro-survival, endoplasmic reticulum (ER) stress response gene involved in tumor cell adaptation to nutrient availability.

    PubMed

    Méndez-Lucas, Andrés; Hyroššová, Petra; Novellasdemunt, Laura; Viñals, Francesc; Perales, Jose C

    2014-08-01

    Mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M), encoded by the nuclear PCK2 gene, links TCA cycle intermediates and glycolytic pools through the conversion of mitochondrial oxaloacetate into phosphoenolpyruvate. In the liver PEPCK-M adjoins its profusely studied cytosolic isoform (PEPCK-C) potentiating gluconeogenesis and TCA flux. However, PEPCK-M is present in a variety of non-gluconeogenic tissues, including tumors of several origins. Despite its potential relevance to cancer metabolism, the mechanisms responsible for PCK2 gene regulation have not been elucidated. The present study demonstrates PEPCK-M overexpression in tumorigenic cells as well as the mechanism for the modulation of PCK2 abundance under several stress conditions. Amino acid limitation and ER stress inducers, conditions that activate the amino acid response (AAR) and the unfolded protein response (UPR), stimulate PCK2 gene transcription. Both the AAR and UPR lead to increased synthesis of ATF4, which mediates PCK2 transcriptional up-regulation through its binding to a putative ATF/CRE composite site within the PCK2 promoter functioning as an amino acid response element. In addition, activation of the GCN2-eIF2α-ATF4 and PERK-eIF2α-ATF4 signaling pathways are responsible for increased PEPCK-M levels. Finally, PEPCK-M knockdown using either siRNA or shRNA were sufficient to reduce MCF7 mammary carcinoma cell growth and increase cell death under glutamine deprivation or ER stress conditions. Our data demonstrate that this enzyme has a critical role in the survival program initiated upon stress and shed light on an unexpected and important role of mitochondrial PEPCK in cancer metabolism. PMID:24973213

  9. Sequence analyses and evolutionary relationships among the energy-coupling proteins Enzyme I and HPr of the bacterial phosphoenolpyruvate: sugar phosphotransferase system.

    PubMed Central

    Reizer, J.; Hoischen, C.; Reizer, A.; Pham, T. N.; Saier, M. H.

    1993-01-01

    We have previously reported the overexpression, purification, and biochemical properties of the Bacillus subtilis Enzyme I of the phosphoenolpyruvate: sugar phosphotransferase system (PTS) (Reizer, J., et al., 1992, J. Biol. Chem. 267, 9158-9169). We now report the sequencing of the ptsI gene of B. subtilis encoding Enzyme I (570 amino acids and 63,076 Da). Putative transcriptional regulatory signals are identified, and the pts operon is shown to be subject to carbon source-dependent regulation. Multiple alignments of the B. subtilis Enzyme I with (1) six other sequenced Enzymes I of the PTS from various bacterial species, (2) phosphoenolpyruvate synthase of Escherichia coli, and (3) bacterial and plant pyruvate: phosphate dikinases (PPDKs) revealed regions of sequence similarity as well as divergence. Statistical analyses revealed that these three types of proteins comprise a homologous family, and the phylogenetic tree of the 11 sequenced protein members of this family was constructed. This tree was compared with that of the 12 sequence HPr proteins or protein domains. Antibodies raised against the B. subtilis and E. coli Enzymes I exhibited immunological cross-reactivity with each other as well as with PPDK of Bacteroides symbiosus, providing support for the evolutionary relationships of these proteins suggested from the sequence comparisons. Putative flexible linkers tethering the N-terminal and the C-terminal domains of protein members of the Enzyme I family were identified, and their potential significance with regard to Enzyme I function is discussed. The codon choice pattern of the B. subtilis and E. coli ptsI and ptsH genes was found to exhibit a bias toward optimal codons in these organisms.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7686067

  10. 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.

    PubMed

    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. PMID:26712095

  11. Activities of Ribulose Bisphosphate Carboxylase and Phosphoenolpyruvate Carboxylase and 14C-Bicarbonate Fixation during in Vitro Culture of Pinus radiata Cotyledons 1

    PubMed Central

    Kumar, Prakash P.; Bender, Ludwig; Thorpe, Trevor A.

    1988-01-01

    The activities of ribulose bisphosphate carboxylase (RuBPC) and phosphoenolpyruvate carboxylase (PEPC), as indicators of autotrophic and nonautotrophic CO2 fixation, were measured in excised cotyledons of Pinus radiata D. Don cultured for 21 days under shoot-forming (SF) and nonshoot-forming (NSF) conditions. The activity of RuBPC was found to increase in both SF and NSF cultures during the initial 5 days of culture. However, it leveled off from day 5 to day 10 and subsequently began to decrease until the end of the culture period under the SF conditions. In contrast, in the NSF cultures, RuBPC activity increased until day 15, when it was twofold higher than the maximum activity found in the SF cultures. An increase in PEPC activity of about 2.5 times the level of activity in freshly excised cotyledons was observed during the initial 5 days of culture under the SF conditions. PEPC activity began to decline after day 5 until it reached the level of activity seen in NSF cotyledons by day 15. In contrast, the activity of PEPC did not show any significant increase during the initial 10 days of culture under the NSF conditions. The Km (phosphoenolpyruvate) of PEPC from SF cotyledons was about 35% higher than that of NSF cotyledons. Cotyledons from two culture periods (days 5 and 15) were incubated for 15 seconds with NaH14CO3. The label in the malate and asparatate fractions as a percentage of total 14C incorporation was 3 times higher in the SF cotyledons than in the NSF cotyledons. A higher incorporation of 14C into products of photosynthesis under the NSF conditions was also observed. PMID:16666206

  12. New insights into the post-translational modification of multiple phosphoenolpyruvate carboxylase isoenzymes by phosphorylation and monoubiquitination during sorghum seed development and germination

    PubMed Central

    Ruiz-Ballesta, Isabel; Baena, Guillermo; Gandullo, Jacinto; Wang, Liqun; She, Yi-Min; Plaxton, William Charles; Echevarría, Cristina

    2016-01-01

    Phosphoenolpyruvate carboxylase (PEPC; E.C. 4.1.1.31) was characterized in developing and germinating sorghum seeds, focusing on the transcript and polypeptide abundance of multiple plant-type phosphoenolpyruvate carboxylase (PTPC) genes, and the post-translational modification of each isoenzyme by phosphorylation versus monoubiquitination during germination. We observed high levels of SbPPC4 (Sb07g014960) transcripts during early development (stage I), and extensive transcript abundance of SbPPC2 (Sb02g021090) and SbPPC3 (Sb04g008720) throughout the entire life cycle of the seed. Although tandem mass spectrometry (MS) analysis of immunopurified PTPC indicated that four different PTPC isoenzymes were expressed in the developing and germinating seeds, SbPPC3 was the most abundant isozyme of the developing seed, and of the embryo and the aleurone layer of germinating seeds. In vivo phosphorylation of the different PTPC isoenzymes at their conserved N-terminal seryl phosphorylation site during germination was also established by MS/MS analysis. Furthermore, three of the four isoenzymes were partially monoubiquitinated, with MS/MS pinpointing SbPPC2 and SbPPC3 monoubiquitination at the conserved Lys-630 and Lys-624 residues, respectively. Our results demonstrate that monoubiquitination and phosphorylation simultaneously occur in vivo with different PTPC isozymes during seed germination. In addition, we show that PTPC monoubiquitination in germinating sorghum seeds always increases at stage II (emergence of the radicle), is maintained during the aerobic period of rapid cell division and reserve mobilization, and remains relatively constant until stage IV–V when coleoptiles initiate the formation of the photosynthetic tissues. PMID:27194739

  13. New insights into the post-translational modification of multiple phosphoenolpyruvate carboxylase isoenzymes by phosphorylation and monoubiquitination during sorghum seed development and germination.

    PubMed

    Ruiz-Ballesta, Isabel; Baena, Guillermo; Gandullo, Jacinto; Wang, Liqun; She, Yi-Min; Plaxton, William Charles; Echevarría, Cristina

    2016-05-01

    Phosphoenolpyruvate carboxylase (PEPC; E.C. 4.1.1.31) was characterized in developing and germinating sorghum seeds, focusing on the transcript and polypeptide abundance of multiple plant-type phosphoenolpyruvate carboxylase (PTPC) genes, and the post-translational modification of each isoenzyme by phosphorylation versus monoubiquitination during germination. We observed high levels of SbPPC4 (Sb07g014960) transcripts during early development (stage I), and extensive transcript abundance of SbPPC2 (Sb02g021090) and SbPPC3 (Sb04g008720) throughout the entire life cycle of the seed. Although tandem mass spectrometry (MS) analysis of immunopurified PTPC indicated that four different PTPC isoenzymes were expressed in the developing and germinating seeds, SbPPC3 was the most abundant isozyme of the developing seed, and of the embryo and the aleurone layer of germinating seeds. In vivo phosphorylation of the different PTPC isoenzymes at their conserved N-terminal seryl phosphorylation site during germination was also established by MS/MS analysis. Furthermore, three of the four isoenzymes were partially monoubiquitinated, with MS/MS pinpointing SbPPC2 and SbPPC3 monoubiquitination at the conserved Lys-630 and Lys-624 residues, respectively. Our results demonstrate that monoubiquitination and phosphorylation simultaneously occur in vivo with different PTPC isozymes during seed germination. In addition, we show that PTPC monoubiquitination in germinating sorghum seeds always increases at stage II (emergence of the radicle), is maintained during the aerobic period of rapid cell division and reserve mobilization, and remains relatively constant until stage IV-V when coleoptiles initiate the formation of the photosynthetic tissues. PMID:27194739

  14. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface...

  15. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  16. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  17. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  18. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface...

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

    PubMed

    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. PMID:24276160

  20. Near infrared leaf reflectance modeling

    NASA Technical Reports Server (NTRS)

    Parrish, J. B.

    1985-01-01

    Near infrared leaf reflectance modeling using Fresnel's equation (Kumar and Silva, 1973) and Snell's Law successfully approximated the spectral curve for a 0.25-mm turgid oak leaf lying on a Halon background. Calculations were made for ten interfaces, air-wax, wax-cellulose, cellulose-water, cellulose-air, air-water, and their inverses. A water path of 0.5 mm yielded acceptable results, and it was found that assignment of more weight to those interfaces involving air versus water or cellulose, and less to those involving wax, decreased the standard deviation of the error for all wavelengths. Data suggest that the air-cell interface is not the only important contributor to the overall reflectance of a leaf. Results also argue against the assertion that the near infrared plateau is a function of cell structure within the leaf.

  1. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf

    PubMed Central

    Simonin, Kevin A.; Burns, Emily; Choat, Brendan; Barbour, Margaret M.; Dawson, Todd E.; Franks, Peter J.

    2015-01-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem–leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO2 concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO2 concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO2 on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem–leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO2 assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  2. Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf.

    PubMed

    Simonin, Kevin A; Burns, Emily; Choat, Brendan; Barbour, Margaret M; Dawson, Todd E; Franks, Peter J

    2015-03-01

    Leaf hydraulic conductance (k leaf) is a central element in the regulation of leaf water balance but the properties of k leaf remain uncertain. Here, the evidence for the following two models for k leaf in well-hydrated plants is evaluated: (i) k leaf is constant or (ii) k leaf increases as transpiration rate (E) increases. The difference between stem and leaf water potential (ΔΨstem-leaf), stomatal conductance (g s), k leaf, and E over a diurnal cycle for three angiosperm and gymnosperm tree species growing in a common garden, and for Helianthus annuus plants grown under sub-ambient, ambient, and elevated atmospheric CO₂ concentration were evaluated. Results show that for well-watered plants k leaf is positively dependent on E. Here, this property is termed the dynamic conductance, k leaf(E), which incorporates the inherent k leaf at zero E, which is distinguished as the static conductance, k leaf(0). Growth under different CO₂ concentrations maintained the same relationship between k leaf and E, resulting in similar k leaf(0), while operating along different regions of the curve owing to the influence of CO₂ on g s. The positive relationship between k leaf and E minimized variation in ΔΨstem-leaf. This enables leaves to minimize variation in Ψleaf and maximize g s and CO₂ assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  3. Leaf proteomic analysis of three rice heritable mutants after seed space flight

    NASA Astrophysics Data System (ADS)

    Wang, W.; Gu, D. P.; Zheng, Q.; Sun, Y. Q.

    2008-09-01

    To explore the proteomic changes of heritable variant rice plants induced by space environment, three mutants were selected after seed space flight by comparing the phenotypes with their on-ground controls. R955 grew more tillers and became dwarf, 971-5 acquired higher grain yield and better stress resistance, 974-5 matured earlier. Leaf proteins were extracted during the tiller development and analyzed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). More than 300 proteins were detected as reproducible Coomassie Brilliant Blue stained spots with p I values from around 4.0 to 7.0. Five proteins that changed significantly over the controls were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The main functions of these proteins were photosynthesis, stress defense and metabolism including RuBisCO activase, glycine rich RNA binding protein, peroxidase, triosephosphate isomerase and phosphoenolpyruvate carboxylase, which might be probably associated with the altered phenotypes. Quantitative analyses were also applied: less total protein spots and more down-regulated protein spots were detected in the mutants, indicating there might be a major loss of protein in heritable variant rice plants after seed space flight. These results may provide new insights to understand the biological effects of space environment to rice.

  4. Leaf nitrogen dioxide uptake coupling apoplastic chemistry, carbon/sulfur assimilation, and plant nitrogen status.

    PubMed

    Hu, Yanbo; Sun, Guangyu

    2010-10-01

    Emission and plant uptake of atmospheric nitrogen oxides (NO + NO(2)) significantly influence regional climate change by regulating the oxidative chemistry of the lower atmosphere, species composition and the recycling of carbon and nutrients, etc. Plant uptake of nitrogen dioxide (NO(2)) is concentration-dependent and species-specific, and covaries with environmental factors. An important factor determining NO(2) influx into leaves is the replenishment of the substomatal cavity. The apoplastic chemistry of the substomatal cavity plays crucial roles in NO(2) deposition rates and the tolerance to NO(2), involving the reactions between NO(2) and apoplastic antioxidants, NO(2)-responsive germin-like proteins, apoplastic acidification, and nitrite-dependent NO synthesis, etc. Moreover, leaf apoplast is a favorable site for the colonization by microbes, which disturbs nitrogen metabolism of host plants. For most plant species, NO(2) assimilation in a leaf primarily depends on the nitrate (NO(3) (-)) assimilation pathway. NO(2)-N assimilation is coupled with carbon and sulfur (sulfate and SO(2)) assimilation as indicated by the mutual needs for metabolic intermediates (or metabolites) and the NO(2)-caused changes of key metabolic enzymes such as phosphoenolpyruvate carboxylase (PEPc) and adenosine 5'-phosphosulfate sulfotransferase, organic acids, and photorespiration. Moreover, arbuscular mycorrhizal (AM) colonization improves the tolerance of host plants to NO(2) by enhancing the efficiency of nutrient absorption and translocation and influencing foliar chemistry. Further progress is proposed to gain a better understanding of the coordination between NO(2)-N, S and C assimilation, especially the investigation of metabolic checkpoints, and the effects of photorespiratory nitrogen cycle, diverse PEPc and the metabolites such as cysteine, O-acetylserine (OAS) and glutathione. PMID:20628880

  5. Functional relationships of leafing intensity to plant height, growth form and leaf habit

    NASA Astrophysics Data System (ADS)

    Yan, En-Rong; Milla, Rubén; Aarssen, Lonnie W.; Wang, Xi-Hua

    2012-05-01

    Leafing intensity, i.e. the number of leaves per unit of stem volume or mass, is a common developmental correlate of leaf size. However, the ecological significance and the functional implications of variation in leafing intensity, other than its relation to leaf size, are unknown. Here, we explore its relationships with plant height, growth form, leaf size, and leaf habit to test a series of corollaries derived from the leafing intensity premium hypothesis. Volume-based leafing intensities and plant heights were recorded for 109 woody species from the subtropical evergreen broadleaf forests of eastern China. In addition, we compiled leafing intensity data from published literature, and combined it with our data to form a 398 species dataset, to test for differences of leafing intensity between plant growth forms (i.e. herbaceous and woody) and leaf habits (i.e. deciduous and evergreens). Leafing intensity was negatively correlated with plant height and individual leaf mass. Volume-based leafing intensities were significantly higher in herbaceous species than in woody species, and also higher in deciduous than in evergreen woody species. In conclusion, leafing intensity relates strongly to plant height, growth form, leaf size, and leaf habit in directions generally in accordance to the leafing intensity premium hypothesis. These results can be interpreted in terms of the evolution of adaptive strategies involving response to herbivory, competitive ability for light and reproductive economy.

  6. How to pattern a leaf.

    PubMed

    Bolduc, N; O'Connor, D; Moon, J; Lewis, M; Hake, S

    2012-01-01

    Leaf development presents a tremendous resource for tackling the question of patterning in biology. Leaves can be simple or highly dissected. They may have elaborated parts such as the tendrils of a pea leaf or the rolled blade of a carnivorous pitcher plant. Despite the variation in size, shape, and function, all leaves initiate in the same manner: from the flanks of a meristem. The maize leaf is useful for analysis of patterning due to the wealth of mutants and the distinct tissues along the proximal distal axis. The blade is distal, the sheath is proximal, and the ligule forms at the blade/sheath boundary. Establishment of this boundary involves the transcription factors LIGULELESS1 and LIGULELESS2 and the kinase LIGULELESS NARROW. The meristem-specific protein KNOTTED1 (KN1) binds and modulates the lg2 gene. Given the localization of KN1 at the proximal end of the leaf from the time of inception, we hypothesize that KN1 has a role in establishing the very proximal end of the leaf, whereas an auxin maximum guides the growing distal tip. PMID:23174765

  7. Biophysical control of leaf temperature

    NASA Astrophysics Data System (ADS)

    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

  8. Behavior of Leaf Meristems and Their Modification

    PubMed Central

    Ichihashi, Yasunori; Tsukaya, Hirokazu

    2015-01-01

    A major source of diversity in flowering plant form is the extensive variability of leaf shape and size. Leaf formation is initiated by recruitment of a handful of cells flanking the shoot apical meristem (SAM) to develop into a complex three-dimensional structure. Leaf organogenesis depends on activities of several distinct meristems that are established and spatiotemporally differentiated after the initiation of leaf primordia. Here, we review recent findings in the gene regulatory networks that orchestrate leaf meristem activities in a model plant Arabidopsis thaliana. We then discuss recent key studies investigating the natural variation in leaf morphology to understand how the gene regulatory networks modulate leaf meristems to yield a substantial diversity of leaf forms during the course of evolution. PMID:26648955

  9. Relationships between sugarcane leaf hyperspectral reflectance, leaf nitrogen content, and yield components

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf spectral reflectance has been used to estimate crop leaf chemical composition and other physiological characters. Leaf reflectance of sugarcane (Saccharum spp.) may be of use in evaluating genotypes. The objectives of this study were: (1) to identify sugarcane genotypic variation in leaf hypers...

  10. Analysis of Circadian Leaf Movements.

    PubMed

    Müller, Niels A; Jiménez-Gómez, José M

    2016-01-01

    The circadian clock is a molecular timekeeper that controls a wide variety of biological processes. In plants, clock outputs range from the molecular level, with rhythmic gene expression and metabolite content, to physiological processes such as stomatal conductance or leaf movements. Any of these outputs can be used as markers to monitor the state of the circadian clock. In the model plant Arabidopsis thaliana, much of the current knowledge about the clock has been gained from time course experiments profiling expression of endogenous genes or reporter constructs regulated by the circadian clock. Since these methods require labor-intensive sample preparation or transformation, monitoring leaf movements is an interesting alternative, especially in non-model species and for natural variation studies. Technological improvements both in digital photography and image analysis allow cheap and easy monitoring of circadian leaf movements. In this chapter we present a protocol that uses an autonomous point and shoot camera and free software to monitor circadian leaf movements in tomato. PMID:26867616

  11. Exobasidium leaf and fruit spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    During the past five or so years blueberry growers in south Mississippi have discovered the disease Exobasidium leaf and fruit spot on some of their blueberry plants. In the past this disease was considered to be of minor importance occurring infrequently on isolated farms. But in recent years it ...

  12. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    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...

  13. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  14. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  15. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  16. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  17. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  18. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 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,...

  19. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  20. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  1. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  2. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  3. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 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,...

  4. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  5. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  6. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  7. Tree branch angle: maximizing effective leaf area.

    PubMed

    Honda, H; Fisher, J B

    1978-02-24

    In a computer simulation of branching pattern and leaf cluster in Terminalia catappa, right and left branch angles were varied, and the effective leaf surface areas were calculated. Theoretical branch angles that result in maximum effective leaf area are close to the values observed in nature. PMID:17757590

  8. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  9. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.3526 Section 29.3526...

  10. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2529 Section 29.2529...

  11. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022...

  12. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.2277 Section 29.2277...

  13. Comparison of half and full-leaf shape feature extraction for leaf classification

    NASA Astrophysics Data System (ADS)

    Sainin, Mohd Shamrie; Ahmad, Faudziah; Alfred, Rayner

    2016-08-01

    Shape is the main information for leaf feature that most of the current literatures in leaf identification utilize the whole leaf for feature extraction and to be used in the leaf identification process. In this paper, study of half-leaf features extraction for leaf identification is carried out and the results are compared with the results obtained from the leaf identification based on a full-leaf features extraction. Identification and classification is based on shape features that are represented as cosines and sinus angles. Six single classifiers obtained from WEKA and seven ensemble methods are used to compare their performance accuracies over this data. The classifiers were trained using 65 leaves in order to classify 5 different species of preliminary collection of Malaysian medicinal plants. The result shows that half-leaf features extraction can be used for leaf identification without decreasing the predictive accuracy.

  14. Impact of the core components of the phosphoenolpyruvate-carbohydrate phosphotransferase system, HPr and EI, on differential protein expression in Ralstonia eutropha H16.

    PubMed

    Kaddor, Chlud; Voigt, Birgit; Hecker, Michael; Steinbüchel, Alexander

    2012-07-01

    In Ralstonia eutropha H16, seven genes encoding proteins being involved in the phosphoenolpyruvate-carbohydrate phosphotransferase system (PEP-PTS) were identified. In order to provide more insights into the poly(3-hydroxybutyrate) (PHB)-leaky phenotype of the HPr/EI deletion mutants H16ΔptsH, H16ΔptsI, and H16ΔptsHI when grown on the non-PTS substrate gluconate, parallel fermentations for comparison of their growth behavior were performed. Samples from the exponential, the early stationary, and late stationary growth phases were investigated by microscopy, gas chromatography and (phospho-) proteome analysis. A total of 71 differentially expressed proteins were identified using 2D-PAGE, Pro-Q Diamond and Coomassie staining, and MALDI-TOF analysis. Detected proteins were classified into five major functional groups: carbon metabolism, energy metabolism, amino acid metabolism, translation, and membrane transport/outer membrane proteins. Proteome analyses revealed enhanced expression of proteins involved in the Entner-Doudoroff pathway and in subsequent reactions in cells of strain H16 compared to the mutant H16ΔptsHI. Furthermore, proteins involved in PHB accumulation showed increased abundance in the wild-type. This expression pattern allowed us to identify proteins affecting carbon metabolism/PHB biosynthesis in strain H16 and translation/amino acid metabolism in strain H16ΔptsHI, and to gain insight into the molecular response of R. eutropha to the deletion of HPr/EI. PMID:22630130

  15. Integration and expression of Sorghum C(4) phosphoenolpyruvate carboxylase and chloroplastic NADP(+)-malate dehydrogenase separately or together in C(3) potato plants(1).

    PubMed

    Beaujean, A; Issakidis-Bourguet, E; Catterou, M; Dubois, F; Sangwan, R S.; Sangwan-Norreel, B S.

    2001-05-01

    We have integrated two cDNAs expressing Sorghum photosynthetic phosphoenolpyruvate carboxylase (C(4)-PEPC) and NADP-malate dehydrogenase (cpMDH), two key enzymes involved in the primary carbon fixation pathway of NADP-malic enzyme-type C(4) plants, separately or together into a C(3) plant (potato). Analysis of the transgenic plants showed a 1.5-fold increase in PEPC and cpMDH activities compared to untransformed plants. Immunolocalization confirmed an increase at the protein level of these two enzymes in the transgenic plants and indicated that the Sorghum cpMDH was specifically addressed to the chloroplasts of potato mesophyll cells. However, integration of either or both of the cDNAs into the potato genome did not appear to significantly modify either tuber starch grain content or the rate of photosynthetic O(2) production compared to control untransformed plants. The low level of transgene expression probably explains the lack of influence on carbon metabolism and photosynthetic rates. This general observation suggests that some complex mechanism may regulate the level of production of foreign C(4) metabolism enzymes in C(3) plants. PMID:11337077

  16. Tissue-specific, developmental, hormonal, and dietary regulation of rat phosphoenolpyruvate carboxykinase-human growth hormone fusion genes in transgenic mice.

    PubMed Central

    Short, M K; Clouthier, D E; Schaefer, I M; Hammer, R E; Magnuson, M A; Beale, E G

    1992-01-01

    The cytosolic phosphoenolpyruvate carboxykinase (PEPCK) gene is expressed in multiple tissues and is regulated in a complex tissue-specific manner. To map the cis-acting DNA elements that direct this tissue-specific expression, we made transgenic mice containing truncated PEPCK-human growth hormone (hGH) fusion genes. The transgenes contained PEPCK promoter fragments with 5' endpoints at -2088, -888, -600, -402, and -207 bp, while the 3' endpoint was at +69 bp. Immunohistochemical analysis showed that the -2088 transgene was expressed in the correct cell types (hepatocytes, proximal tubular epithelium of the kidney, villar epithelium of the small intestine, epithelium of the colon, smooth muscle of the vagina and lungs, ductal epithelium of the sublingual gland, and white and brown adipocytes). Solution hybridization of hGH mRNA expressed from the transgenes indicated that white and brown fat-specific elements are located distally (-2088 to -888 bp) and that liver-, gut-, and kidney-specific elements are located proximally (-600 to +69 bp). However, elements outside of the region tested are necessary for the correct developmental pattern and level of PEPCK expression in kidney. Both the -2088 and -402 transgenes responded in a tissue-specific manner to dietary stimuli, and the -2088 transgene responded to glucocorticoid stimuli. Thus, different tissues utilize distinct cell-specific cis-acting elements to direct and regulate the PEPCK gene. Images PMID:1545785

  17. Phosphorylation of phosphoenolpyruvate carboxykinase in plants. Studies in plants with C4 photosynthesis and Crassulacean acid metabolism and in germinating seeds.

    PubMed Central

    Walker, R P; Leegood, R C

    1996-01-01

    We have previously shown that phosphoenolpyruvate carboxykinase (PEPCK) is phosphorylated in vivo in the cotyledons of darkened cucumber seedlings and that phosphorylation is reversed by light [Walker and Leegood (1995) FEBS Lett. 362, 70-74]. In this study the molecular mass of PEPCK was estimated in a range of gluconeogenic seedlings and in leaves of C4 plants and plants with Crassulacean acid metabolism (CAM). Phosphorylation of PEPCK was studied in these plants by feeding tissues with [32P]Pi and assessing phosphorylation by SDS/PAGE and autoradiography of either total proteins or of immunoprecipitated protein. In gluconeogenic seedlings and most CAM plants PEPCK had a molecular mass of 74 kDa, whereas in C4 grasses the molecular mass of PEPCK was always smaller and varied from 67-71 kDa. In all gluconeogenic seedlings and leaves of CAM plants PEPCK was phosphorylated, but it was not phosphorylated in all species of C4 grasses studied. In CAM plants, phosphorylation of PEPCK occurred at night and dephosphorylation occurred during the day. In C4 grasses phosphorylation occurred when leaves were darkened and the enzyme was dephosphorylated following illumination, but it was only phosphorylated in those plants with larger (71 kDa) molecular mass forms of PEPCK. PMID:8760346

  18. The glycolytic genes pfk and pyk from Lactobacillus casei are induced by sugars transported by the phosphoenolpyruvate:sugar phosphotransferase system and repressed by CcpA.

    PubMed

    Viana, Rosa; Pérez-Martínez, Gaspar; Deutscher, Josef; Monedero, Vicente

    2005-09-01

    In Lactobacillus casei BL23, phosphofructokinase activity was higher in cells utilizing sugars transported by the phosphoenolpyruvate:sugar phosphotransferase system (PTS). The phosphofructokinase gene (pfk) was cloned from L. casei and shown to be clustered with the gene encoding pyruvate kinase (pyk). pfk and pyk genes are cotranscribed and induced upon growth on sugars transported by the PTS. Contrarily to the model proposed for Lactococcus lactis, where the global catabolite regulator protein (CcpA) is involved in PTS-induced transcription of pfk and pyk, a ccpA mutation resulted in a slight increase in pfk-pyk expression in L. casei. This weak regulation was evidenced by CcpA binding to a region of the pfk-pyk promoter which contained two cre sequences significantly deviated from the consensus. The PTS induction of pfk-pyk seems to be counteracted by the CcpA-mediated repression. Our results suggest that the need to accommodate the levels of pfk-pyk mRNA to the availability of sugars is fulfilled in L. casei by a PTS/CcpA-mediated signal transduction different from L. lactis. PMID:16075200

  19. Phosphoenolpyruvate Carboxykinase, a Key Enzyme That Controls Blood Glucose, Is a Target of Retinoic Acid Receptor-Related Orphan Receptor α

    PubMed Central

    Matsuoka, Hiroshi; Shima, Akiho; Kuramoto, Daisuke; Kikumoto, Daisuke; Matsui, Takashi; Michihara, Akihiro

    2015-01-01

    Phosphoenolpyruvate carboxykinase (PEPCK) catalyzes a committed and rate-limiting step in hepatic gluconeogenesis, and its activity is tightly regulated to maintain blood glucose levels within normal limits. PEPCK activity is primarily regulated through hormonal control of gene transcription. Transcription is additionally regulated via a cAMP response unit, which includes a cAMP response element and four binding sites for CCAAT/enhancer-binding protein (C/EBP). Notably, the cAMP response unit also contains a putative response element for retinoic acid receptor-related orphan receptor α (RORα). In this paper, we characterize the effect of the RORα response element on cAMP-induced transcription. Electrophoresis mobility shift assay indicates that RORα binds this response element in a sequence-specific manner. Furthermore, luciferase reporter assays indicate that RORα interacts with C/EBP at the PEPCK promoter to synergistically enhance transcription. We also found that cAMP-induced transcription depends in part on RORα and its response element. In addition, we show that suppression of RORα by siRNA significantly decreased PEPCK transcription. Finally, we found that a RORα antagonist inhibits hepatic gluconeogenesis in an in vitro glucose production assay. Taken together, the data strongly suggest that PEPCK is a direct RORα target. These results define possible new roles for RORα in hepatic gluconeogenesis. PMID:26383638

  20. Cloning of cellobiose phosphoenolpyruvate-dependent phosphotransferase genes: Functional expression in recombinant Escherichia coli and identification of a putative binding region for disaccharides

    SciTech Connect

    Lai, Xiaokuang; Davis, F.C.; Ingram, L.O.; Hespell, R.B.

    1997-02-01

    Genomic libraries from nine cellobiose-metabolizing bacteria were screened for cellobiose utilization. Positive clones were recovered from six libraries, all of which encode phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) proteins. Clones from Bacillus subtilis, Butyrivibrio fibrisolvens, and Klebsiella oxytoca allowed the growth of recombinant Escherichia coli in cellobiose-M9 minimal medium. The K. oxytoca clone, pLOI1906, exhibited an unusually broad substrate range (cellobiose, arbutin, salicin, and methylumbelliferyl derivatives of glucose, cellobiose, mannose, and xylose) and was sequenced. The insert in this plasmid encoded the carboxy-terminal region of a putative regulatory protein, cellobiose permease (single polypeptide), and phospho-{beta}-glucosidase, which appear to form an operon (casRAB). Subclones allowed both casA and casB to be expressed independently, as evidenced by in vitro complementation. An analysis of the translated sequences from the EIIC domains of cellobiose, aryl-{beta}-glucoside, and other disaccharide permeases allowed the identification of a 50-amino-acid conserved region. A disaccharide consensus sequence is proposed for the most conserved segment (13 amino acids), which may represent part of the EIIC active site for binding and phosphorylation. 63 refs., 4 figs., 4 tabs.

  1. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  2. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  3. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  4. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... specifications, and tolerances C1L Choice Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth... injury tolerance. C2L Fine Quality Light-brown Thin Leaf. Ripe, thin, open leaf structure, smooth, oily... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  5. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... tolerance. C4L Fair Quality Light-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in oil... tolerance. C5L Low Quality Light-brown Thin Leaf Underripe, thin, close leaf structure, rough, lean in oil... tolerance. C4F Fair Quality Medium-brown Thin Leaf. Mature, thin, close leaf structure, rough, lean in...

  6. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  7. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  8. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  9. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  10. 7 CFR 29.1162 - Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Specifications, and Tolerances B1L—Choice Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil... percent. B2L—Fine Quality Lemon Leaf Ripe, firm leaf structure, medium body, rich in oil, deep color.... B3L—Good Quality Lemon Leaf Ripe, firm leaf structure, medium body, oily, strong color...

  11. SPAD-based leaf nitrogen estimation is impacted by environmental factors and crop leaf characteristics

    PubMed Central

    Xiong, Dongliang; Chen, Jia; Yu, Tingting; Gao, Wanlin; Ling, Xiaoxia; Li, Yong; Peng, Shaobing; Huang, Jianliang

    2015-01-01

    Chlorophyll meters are widely used to guide nitrogen (N) management by monitoring leaf N status in agricultural systems, but the effects of environmental factors and leaf characteristics on leaf N estimations are still unclear. In the present study, we estimated the relationships among SPAD readings, chlorophyll content and leaf N content per leaf area for seven species grown in multiple environments. There were similar relationships between SPAD readings and chlorophyll content per leaf area for the species groups, but the relationship between chlorophyll content and leaf N content per leaf area, and the relationship between SPAD readings and leaf N content per leaf area varied widely among the species groups. A significant impact of light-dependent chloroplast movement on SPAD readings was observed under low leaf N supplementation in both rice and soybean but not under high N supplementation. Furthermore, the allocation of leaf N to chlorophyll was strongly influenced by short-term changes in growth light. We demonstrate that the relationship between SPAD readings and leaf N content per leaf area is profoundly affected by environmental factors and leaf features of crop species, which should be accounted for when using a chlorophyll meter to guide N management in agricultural systems. PMID:26303807

  12. Leaf physiognomy and climate: A multivariate analysis

    NASA Astrophysics Data System (ADS)

    Davis, J. M.; Taylor, S. E.

    1980-11-01

    Research has demonstrated that leaf physiognomy is representative of the local or microclimate conditions under which plants grow. The physiognomy of leaf samples from Oregon, Michigan, Missouri, Tennessee, and the Panama Canal Zone has been related to the microclimate using Walter diagrams and Thornthwaite water-budget data. A technique to aid paleoclimatologists in identifying the nature of the microclimate from leaf physiognomy utilizes statistical procedures to classify leaf samples into one of six microclimate regimes based on leaf physiognomy information available from fossilized samples.

  13. Hormonal regulation of leaf senescence in Lilium.

    PubMed

    Arrom, Laia; Munné-Bosch, Sergi

    2012-10-15

    In addition to floral senescence and longevity, the control of leaf senescence is a major factor determining the quality of several cut flowers, including Lilium, in the commercial market. To better understand the physiological process underlying leaf senescence in this species, we evaluated: (i) endogenous variation in the levels of phytohormones during leaf senescence, (ii) the effects of leaf darkening in senescence and associated changes in phytohormones, and (iii) the effects of spray applications of abscisic acid (ABA) and pyrabactin on leaf senescence. Results showed that while gibberellin 4 (GA(4)) and salicylic acid (SA) contents decreased, that of ABA increased during the progression of leaf senescence. However, dark-induced senescence increased ABA levels, but did not affect GA(4) and SA levels, which appeared to correlate more with changes in air temperature and/or photoperiod than with the induction of leaf senescence. Furthermore, spray applications of pyrabactin delayed the progression of leaf senescence in cut flowers. Thus, we conclude that (i) ABA plays a major role in the regulation of leaf senescence in Lilium, (ii) darkness promotes leaf senescence and increases ABA levels, and (iii) exogenous applications of pyrabactin inhibit leaf senescence in Lilium, therefore suggesting that it acts as an antagonist of ABA in senescing leaves of cut lily flowers. PMID:22854182

  14. Leaf herbivory and nutrients increase nectar alkaloids.

    PubMed

    Adler, Lynn S; Wink, Michael; Distl, Melanie; Lentz, Amanda J

    2006-08-01

    Correlations between traits may constrain ecological and evolutionary responses to multispecies interactions. Many plants produce defensive compounds in nectar and leaves that could influence interactions with pollinators and herbivores, but the relationship between nectar and leaf defences is entirely unexplored. Correlations between leaf and nectar traits may be mediated by resources and prior damage. We determined the effect of nutrients and leaf herbivory by Manduca sexta on Nicotiana tabacum nectar and leaf alkaloids, floral traits and moth oviposition. We found a positive phenotypic correlation between nectar and leaf alkaloids. Herbivory induced alkaloids in nectar but not in leaves, while nutrients increased alkaloids in both tissues. Moths laid the most eggs on damaged, fertilized plants, suggesting a preference for high alkaloids. Induced nectar alkaloids via leaf herbivory indicate that species interactions involving leaf and floral tissues are linked and should not be treated as independent phenomena in plant ecology or evolution. PMID:16913940

  15. The relationship of leaf photosynthetic traits - V cmax and J max - to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study.

    PubMed

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-08-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (V cmax) and the maximum rate of electron transport (J max). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between V cmax and J max and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between V cmax and J max and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of V cmax and J max with leaf N, P, and SLA. V cmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of V cmax to leaf N. J max was strongly related to V cmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm(-2)), increasing leaf P from 0.05 to 0.22 gm(-2) nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of J max to V cmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting. PMID:25473475

  16. The relationship of leaf photosynthetic traits – Vcmax and Jmax – to leaf nitrogen, leaf phosphorus, and specific leaf area: a meta-analysis and modeling study

    PubMed Central

    Walker, Anthony P; Beckerman, Andrew P; Gu, Lianhong; Kattge, Jens; Cernusak, Lucas A; Domingues, Tomas F; Scales, Joanna C; Wohlfahrt, Georg; Wullschleger, Stan D; Woodward, F Ian

    2014-01-01

    Great uncertainty exists in the global exchange of carbon between the atmosphere and the terrestrial biosphere. An important source of this uncertainty lies in the dependency of photosynthesis on the maximum rate of carboxylation (Vcmax) and the maximum rate of electron transport (Jmax). Understanding and making accurate prediction of C fluxes thus requires accurate characterization of these rates and their relationship with plant nutrient status over large geographic scales. Plant nutrient status is indicated by the traits: leaf nitrogen (N), leaf phosphorus (P), and specific leaf area (SLA). Correlations between Vcmax and Jmax and leaf nitrogen (N) are typically derived from local to global scales, while correlations with leaf phosphorus (P) and specific leaf area (SLA) have typically been derived at a local scale. Thus, there is no global-scale relationship between Vcmax and Jmax and P or SLA limiting the ability of global-scale carbon flux models do not account for P or SLA. We gathered published data from 24 studies to reveal global relationships of Vcmax and Jmax with leaf N, P, and SLA. Vcmax was strongly related to leaf N, and increasing leaf P substantially increased the sensitivity of Vcmax to leaf N. Jmax was strongly related to Vcmax, and neither leaf N, P, or SLA had a substantial impact on the relationship. Although more data are needed to expand the applicability of the relationship, we show leaf P is a globally important determinant of photosynthetic rates. In a model of photosynthesis, we showed that at high leaf N (3 gm−2), increasing leaf P from 0.05 to 0.22 gm−2 nearly doubled assimilation rates. Finally, we show that plants may employ a conservative strategy of Jmax to Vcmax coordination that restricts photoinhibition when carboxylation is limiting at the expense of maximizing photosynthetic rates when light is limiting. PMID:25473475

  17. Circadian rhythms in crassulacean acid metabolism: phase relationships between gas exchange, leaf water relations and malate metabolism in Kalanchoë daigremontiana.

    PubMed

    Buchanan-Bollig, I C; Smith, J A

    1984-06-01

    Gas exchange, leaf water relations, malate content and phosphoenolpyruvate (PEP) carboxylase activity in crude extracts were examined for circadian rhythmicity in the crassulacean acid metabolism plant Kalanchoë daigremontiana. At low irradiance (20 W m(-2)) the rhythm in CO2 uptake continued for several days with a period length of approx. 22 h, whereas the transpiration rhythm was no longer apparent after 24 h. This shows that the CO2 rhythm in continuous light (LL) is not under stomatal control. Circadian oscillations in malate content were detectable for up to 72 h in LL but were of much reduced amplitude. This was reflected in the changes in leaf water relations, which quickly damped after transfer to LL. The activity of PEP carboxylase assayed immediately after extraction showed a rhythmicity for at least 18 h, but after 36 h, values from different plants were scattered. We suggest that the CO2-uptake rhythm is primarily the result of endogenous changes in the activity of PEP carboxylase, which competes to varying degrees with ribulose-1,5-bisphosphate carboxylase for CO2. PMID:24253720

  18. Leaf Senescence by Magnesium Deficiency

    PubMed Central

    Tanoi, Keitaro; Kobayashi, Natsuko I.

    2015-01-01

    Magnesium ions (Mg2+) are the second most abundant cations in living plant cells, and they are involved in various functions, including photosynthesis, enzyme catalysis, and nucleic acid synthesis. Low availability of Mg2+ in an agricultural field leads to a decrease in yield, which follows the appearance of Mg-deficient symptoms such as chlorosis, necrotic spots on the leaves, and droop. During the last decade, a variety of physiological and molecular responses to Mg2+ deficiency that potentially link to leaf senescence have been recognized, allowing us to reconsider the mechanisms of Mg2+ deficiency. This review focuses on the current knowledge about the physiological responses to Mg2+ deficiency including a decline in transpiration, accumulation of sugars and starch in source leaves, change in redox states, increased oxidative stress, metabolite alterations, and a decline in photosynthetic activity. In addition, we refer to the molecular responses that are thought to be related to leaf senescence. With these current data, we give an overview of leaf senescence induced by Mg deficiency. PMID:27135350

  19. LeafJ: an ImageJ plugin for semi-automated leaf shape measurement.

    PubMed

    Maloof, Julin N; Nozue, Kazunari; Mumbach, Maxwell R; Palmer, Christine M

    2013-01-01

    High throughput phenotyping (phenomics) is a powerful tool for linking genes to their functions (see review and recent examples). Leaves are the primary photosynthetic organ, and their size and shape vary developmentally and environmentally within a plant. For these reasons studies on leaf morphology require measurement of multiple parameters from numerous leaves, which is best done by semi-automated phenomics tools. Canopy shade is an important environmental cue that affects plant architecture and life history; the suite of responses is collectively called the shade avoidance syndrome (SAS). Among SAS responses, shade induced leaf petiole elongation and changes in blade area are particularly useful as indices. To date, leaf shape programs (e.g. SHAPE, LAMINA, LeafAnalyzer, LEAFPROCESSOR) can measure leaf outlines and categorize leaf shapes, but can not output petiole length. Lack of large-scale measurement systems of leaf petioles has inhibited phenomics approaches to SAS research. In this paper, we describe a newly developed ImageJ plugin, called LeafJ, which can rapidly measure petiole length and leaf blade parameters of the model plant Arabidopsis thaliana. For the occasional leaf that required manual correction of the petiole/leaf blade boundary we used a touch-screen tablet. Further, leaf cell shape and leaf cell numbers are important determinants of leaf size. Separate from LeafJ we also present a protocol for using a touch-screen tablet for measuring cell shape, area, and size. Our leaf trait measurement system is not limited to shade-avoidance research and will accelerate leaf phenotyping of many mutants and screening plants by leaf phenotyping. PMID:23380664

  20. Gene expression during wound shock in leaf segments of C sub 3 and C sub 4 plants

    SciTech Connect

    Ghosh, S.; Heikkila, J.J.; Dumbroff, E.B. )

    1989-04-01

    The wound response in two-week-old C{sub 3} (peanut and soybean) and C{sub 4} (sorghum and corn) plants was followed in leaf segments (5 {times} 3 mm) labelled for 2 h with ({sup 35}S)methionine at 0, 2, 4 or 6 h after cutting. Absorption of the radiolabel and its subsequent incorporation into protein reached steady-state levels within 4 to 6 h. The high molecular weight proteins associated with the stress response were induced both by cutting and by exposure of the leaves to high temperatures (40{degree} and 45{degree}C). In sorghum and corn, cutting also increased the synthesis of the 98 and 102 kD forms of phosphoenolpyruvate carboxylase, but only the latter form was stimulated by high temperature. Although several low molecular weight polypeptides were synthesized in response to heat shock, they were not induced in any of the four species by wounding. The control mechanisms involved in the transient would response are currently under investigation.

  1. Effect of Growth Rate and Glucose Concentration on the Activity of the Phosphoenolpyruvate Phosphotransferase System in Streptococcus mutans Ingbritt Grown in Continuous Culture

    PubMed Central

    Ellwood, D. C.; Phipps, P. J.; Hamilton, I. R.

    1979-01-01

    Streptococcus mutans Ingbritt was grown anaerobically in a chemostat with a glucose limitation, as well as with an excess of glucose (amino acid limitation) at dilution rates (D) between 0.05 and 0.4 h−1 (mean generation time = 12 to 1.5 h). The glucose-limited culture produced cells having 1.5- to 6.0-fold greater glycolytic activity than the cells from the glucose-excess culture. The preferred substrate for these cells was glucose, with the glycolytic rate for sucrose being only slightly lower; the rate for fructose was half that of glucose. The glycolytic rate of the glucose-limited cells was maximum at D = 0.1 h−1, with a decline in rate as the growth rate approached D = 0.4 h−1. A comparison of the activity of phosphoenolpyruvate phosphotransferase system (PTS) in the two types of cells showed that the glucose-limited cells had 1.7- to 5.6-fold greater PTS activity for the three sugars than the glucose-excess-grown cells. Whereas little difference was seen between the three sugars with the latter cells, the glucose-PTS had the greatest activity with glucose-limited cells, with the maximum in cells grown at D = 0.1 h−1. Comparison of the rate of sugar uptake in the chemostat with the rate of PTS transport activity in the cells at each growth rate demonstrated that only under conditions of slow growth with a glucose limitation was the PTS system capable of supporting growth on glucose. Furthermore, PTS activity in cells grown with an excess of glucose was insignificant when compared with glucose uptake during growth in the chemostat. This evidence supports the observation that S. mutans possesses at least one other system, in addition to the PTS, for the transport of glucose into the cell. The organism was, however, devoid of glucose-proton symport transport activity. PMID:33901

  2. Regulation of Phosphoenolpyruvate Carboxylase Phosphorylation by Metabolites and Abscisic Acid during the Development and Germination of Barley Seeds1[C][W

    PubMed Central

    Feria, Ana-Belén; Alvarez, Rosario; Cochereau, Ludivine; Vidal, Jean; García-Mauriño, Sofía; Echevarría, Cristina

    2008-01-01

    During barley (Hordeum vulgare) seed development, phosphoenolpyruvate carboxylase (PEPC) activity increased and PEPC-specific antibodies revealed housekeeping (103-kD) and inducible (108-kD) subunits. Bacterial-type PEPC fragments were immunologically detected in denatured protein extracts from dry and imbibed conditions; however, on nondenaturing gels, the activity of the recently reported octameric PEPC (in castor [Ricinus communis] oil seeds) was not detected. The phosphorylation state of the PEPC, as judged by l-malate 50% inhibition of initial activity values, phosphoprotein chromatography, and immunodetection of the phosphorylated N terminus, was found to be high between 8 and 18 d postanthesis (DPA) and during imbibition. In contrast, the enzyme appeared to be in a low phosphorylation state from 20 DPA up to dry seed. The time course of 32/36-kD, Ca2+-independent PEPC kinase activity exhibited a substantial increase after 30 DPA that did not coincide with the PEPC phosphorylation profile. This kinase was found to be inhibited by l-malate and not by putative protein inhibitors, and the PEPC phosphorylation status correlated with high glucose-6-phosphate to malate ratios, thereby suggesting an in vivo metabolic control of the kinase. PEPC phosphorylation was also regulated by photosynthate supply at 11 DPA. In addition, when fed exogenously to imbibing seeds, abscisic acid significantly increased PEPC kinase activity. This was further enhanced by the cytosolic protein synthesis inhibitor cycloheximide but blocked by protease inhibitors, thereby suggesting that the phytohormone acts on the stability of the kinase. We propose that a similar abscisic acid-dependent effect may contribute to produce the increase in PEPC kinase activity during desiccation stages. PMID:18753284

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

    PubMed

    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. PMID:24595619

  4. Reciprocal Control of Anaplerotic Phosphoenolpyruvate Carboxylase by in Vivo Monoubiquitination and Phosphorylation in Developing Proteoid Roots of Phosphate-Deficient Harsh Hakea1[W][OA

    PubMed Central

    Shane, Michael W.; Fedosejevs, Eric T.; Plaxton, William C.

    2013-01-01

    Accumulating evidence indicates important functions for phosphoenolpyruvate (PEP) carboxylase (PEPC) in inorganic phosphate (Pi)-starved plants. This includes controlling the production of organic acid anions (malate, citrate) that are excreted in copious amounts by proteoid roots of nonmycorrhizal species such as harsh hakea (Hakea prostrata). This, in turn, enhances the bioavailability of mineral-bound Pi by solubilizing Al3+, Fe3+, and Ca2+ phosphates in the rhizosphere. Harsh hakea thrives in the nutrient-impoverished, ancient soils of southwestern Australia. Proteoid roots from Pi-starved harsh hakea were analyzed over 20 d of development to correlate changes in malate and citrate exudation with PEPC activity, posttranslational modifications (inhibitory monoubiquitination versus activatory phosphorylation), and kinetic/allosteric properties. Immature proteoid roots contained an equivalent ratio of monoubiquitinated 110-kD and phosphorylated 107-kD PEPC polypeptides (p110 and p107, respectively). PEPC purification, immunoblotting, and mass spectrometry indicated that p110 and p107 are subunits of a 430-kD heterotetramer and that they both originate from the same plant-type PEPC gene. Incubation with a deubiquitinating enzyme converted the p110:p107 PEPC heterotetramer of immature proteoid roots into a p107 homotetramer while significantly increasing the enzyme’s activity under suboptimal but physiologically relevant assay conditions. Proteoid root maturation was paralleled by PEPC activation (e.g. reduced Km [PEP] coupled with elevated I50 [malate and Asp] values) via in vivo deubiquitination of p110 to p107, and subsequent phosphorylation of the deubiquitinated subunits. This novel mechanism of posttranslational control is hypothesized to contribute to the massive synthesis and excretion of organic acid anions that dominates the carbon metabolism of the mature proteoid roots. PMID:23407057

  5. Bacterial- and plant-type phosphoenolpyruvate carboxylase isozymes from developing castor oil seeds interact in vivo and associate with the surface of mitochondria.

    PubMed

    Park, Joonho; Khuu, Nicholas; Howard, Alexander S M; Mullen, Robert T; Plaxton, William C

    2012-07-01

    Phosphoenolpyruvate carboxylase (PEPC) from developing castor oil seeds (COS) exists as two distinct oligomeric isoforms. The typical class-1 PEPC homotetramer consists of 107-kDa plant-type PEPC (PTPC) subunits, whereas the allosterically desensitized 910-kDa class-2 PEPC hetero-octamer arises from the association of class-1 PEPC with 118-kDa bacterial-type PEPC (BTPC) subunits. The in vivo interaction and subcellular location of COS BTPC and PTPC were assessed by imaging fluorescent protein (FP)-tagged PEPCs in tobacco suspension-cultured cells. The BTPC-FP mainly localized to cytoplasmic punctate/globular structures, identified as mitochondria by co-immunostaining of endogenous cytochrome oxidase. Inhibition of respiration with KCN resulted in proportional decreases and increases in mitochondrial versus cytosolic BTPC-FP, respectively. The FP-PTPC and NLS-FP-PTPC (containing an appended nuclear localization signal, NLS) localized to the cytosol and nucleus, respectively, but both co-localized with mitochondrial-associated BTPC when co-expressed with BTPC-FP. Transmission electron microscopy of immunogold-labeled developing COS revealed that BTPC and PTPC are localized at the mitochondrial (outer) envelope, as well as the cytosol. Moreover, thermolysin-sensitive BTPC and PTPC polypeptides were detected on immunoblots of purified COS mitochondria. Overall, our results demonstrate that: (i) COS BTPC and PTPC interact in vivo as a class-2 PEPC complex that associates with the surface of mitochondria, (ii) BTPC's unique and divergent intrinsically disordered region mediates its interaction with PTPC, whereas (iii) the PTPC-containing class-1 PEPC is entirely cytosolic. We hypothesize that mitochondrial-associated class-2 PEPC facilitates rapid refixation of respiratory CO(2) while sustaining a large anaplerotic flux to replenish tricarboxylic acid cycle C-skeletons withdrawn for biosynthesis. PMID:22404138

  6. Streptococcus pneumoniae Cell-Wall-Localized Phosphoenolpyruvate Protein Phosphotransferase Can Function as an Adhesin: Identification of Its Host Target Molecules and Evaluation of Its Potential as a Vaccine

    PubMed Central

    Mizrachi Nebenzahl, Yaffa; Blau, Karin; Kushnir, Tatyana; Shagan, Marilou; Portnoi, Maxim; Cohen, Aviad; Azriel, Shalhevet; Malka, Itai; Adawi, Asad; Kafka, Daniel; Dotan, Shahar; Guterman, Gali; Troib, Shany; Fishilevich, Tali; Gershoni, Jonathan M; Braiman, Alex; Mitchell, Andrea M; Mitchell, Timothy J; Porat, Nurith; Goliand, Inna; Chalifa Caspi, Vered; Swiatlo, Edwin; Tal, Michael; Ellis, Ronald; Elia, Natalie; Dagan, Ron

    2016-01-01

    In Streptococcus pneumonia, phosphoenolpyruvate protein phosphotransferase (PtsA) is an intracellular protein of the monosaccharide phosphotransferase systems. Biochemical and immunostaining methods were applied to show that PtsA also localizes to the bacterial cell-wall. Thus, it was suspected that PtsA has functions other than its main cytoplasmic enzymatic role. Indeed, recombinant PtsA and anti-rPtsA antiserum were shown to inhibit adhesion of S. pneumoniae to cultured human lung adenocarcinoma A549 cells. Screening of a combinatorial peptide library expressed in a filamentous phage with rPtsA identified epitopes that were capable of inhibiting S. pneumoniae adhesion to A549 cells. The insert peptides in the phages were sequenced, and homologous sequences were found in human BMPER, multimerin1, protocadherin19, integrinβ4, epsin1 and collagen type VIIα1 proteins, all of which can be found in A549 cells except the latter. Six peptides, synthesized according to the homologous sequences in the human proteins, specifically bound rPtsA in the micromolar range and significantly inhibited pneumococcal adhesion in vitro to lung- and tracheal-derived cell lines. In addition, the tested peptides inhibited lung colonization after intranasal inoculation of mice with S. pneumoniae. Immunization with rPtsA protected the mice against a sublethal intranasal and a lethal intravenous pneumococcal challenge. In addition, mouse anti rPtsA antiserum reduced bacterial virulence in the intravenous inoculation mouse model. These findings showed that the surface-localized PtsA functions as an adhesin, PtsA binding peptides derived from its putative target molecules can be considered for future development of therapeutics, and rPtsA should be regarded as a candidate for vaccine development. PMID:26990554

  7. Enhanced drought tolerance in transgenic rice over-expressing of maize C4 phosphoenolpyruvate carboxylase gene via NO and Ca(2+).

    PubMed

    Qian, Baoyun; Li, Xia; Liu, Xiaolong; Chen, Pingbo; Ren, Chengang; Dai, Chuanchao

    2015-03-01

    We determined the effects of endogenous nitric oxide and Ca(2+) on photosynthesis and gene expression in transgenic rice plants (PC) over-expressing the maize C4pepc gene, which encodes phosphoenolpyruvate carboxylase (PEPC) under drought. In this study, seedlings were subjected to PEG 6000 treatments using PC and wild type (WT; Kitaake). The results showed that, compared with WT, PC had higher relative water content (RWC) and net photosynthetic rate (Pn) under drought. During a 2-day re-watering treatment, Pn recovered faster in PC than in WT. Further analyses showed that, under the drought treatment, the amount of endogenous hydrogen peroxide (H2O2) increased in WT mainly via NADPH oxidase. While in PC, the endogenous nitric oxide (NO) content increased via nitrate reductase and nitric oxide synthase on day 2 of the drought treatment and day 1 of the re-watering treatment. After 2 days of drought treatment, PC also showed higher PEPC activity, calcium content, phospholipase D (PLD) activity, C4-pepc and NAC6 transcript levels, and protein kinase activity as compared with PC without treatment. These changes did not occur in WT. Correlation analysis also proved NO associated with these indicators in PC. Based on these results, there was a particular molecular mechanism of drought tolerance in PC. The mechanism is related to the signaling processes via NO and Ca(2+) involving the protein kinase and the transcription factor, resulted in up-regulation of PEPC activity and its gene expression, such as C4pepc. Some genes encode antioxidant system, cu/zn-sod as well, which promote antioxidant system to clear MDA and superoxide anion radical, thereby conferring drought tolerance. PMID:25460871

  8. The Phosphoenolpyruvate Phosphotransferase System in Group A Streptococcus Acts To Reduce Streptolysin S Activity and Lesion Severity during Soft Tissue Infection

    PubMed Central

    Gera, Kanika; Le, Tuquynh; Jamin, Rebecca; Eichenbaum, Zehava

    2014-01-01

    Obtaining essential nutrients, such as carbohydrates, is an important process for bacterial pathogens to successfully colonize host tissues. The phosphoenolpyruvate phosphotransferase system (PTS) is the primary mechanism by which bacteria transport sugars and sense the carbon state of the cell. The group A streptococcus (GAS) is a fastidious microorganism that has adapted to a variety of niches in the human body to elicit a wide array of diseases. A ΔptsI mutant (enzyme I [EI] deficient) generated in three different strains of M1T1 GAS was unable to grow on multiple carbon sources (PTS and non-PTS). Complementation with ptsI expressed under its native promoter in single copy was able to rescue the growth defect of the mutant. In a mouse model of GAS soft tissue infection, all ΔptsI mutants exhibited a significantly larger and more severe ulcerative lesion than mice infected with the wild type. Increased transcript levels of sagA and streptolysin S (SLS) activity during exponential-phase growth was observed. We hypothesized that early onset of SLS activity would correlate with the severity of the lesions induced by the ΔptsI mutant. In fact, infection of mice with a ΔptsI sagB double mutant resulted in a lesion comparable to that of either the wild type or a sagB mutant alone. Therefore, a functional PTS is not required for subcutaneous skin infection in mice; however, it does play a role in coordinating virulence factor expression and disease progression. PMID:24379283

  9. Reciprocal control of anaplerotic phosphoenolpyruvate carboxylase by in vivo monoubiquitination and phosphorylation in developing proteoid roots of phosphate-deficient harsh hakea.

    PubMed

    Shane, Michael W; Fedosejevs, Eric T; Plaxton, William C

    2013-04-01

    Accumulating evidence indicates important functions for phosphoenolpyruvate (PEP) carboxylase (PEPC) in inorganic phosphate (Pi)-starved plants. This includes controlling the production of organic acid anions (malate, citrate) that are excreted in copious amounts by proteoid roots of nonmycorrhizal species such as harsh hakea (Hakea prostrata). This, in turn, enhances the bioavailability of mineral-bound Pi by solubilizing Al(3+), Fe(3+), and Ca(2+) phosphates in the rhizosphere. Harsh hakea thrives in the nutrient-impoverished, ancient soils of southwestern Australia. Proteoid roots from Pi-starved harsh hakea were analyzed over 20 d of development to correlate changes in malate and citrate exudation with PEPC activity, posttranslational modifications (inhibitory monoubiquitination versus activatory phosphorylation), and kinetic/allosteric properties. Immature proteoid roots contained an equivalent ratio of monoubiquitinated 110-kD and phosphorylated 107-kD PEPC polypeptides (p110 and p107, respectively). PEPC purification, immunoblotting, and mass spectrometry indicated that p110 and p107 are subunits of a 430-kD heterotetramer and that they both originate from the same plant-type PEPC gene. Incubation with a deubiquitinating enzyme converted the p110:p107 PEPC heterotetramer of immature proteoid roots into a p107 homotetramer while significantly increasing the enzyme's activity under suboptimal but physiologically relevant assay conditions. Proteoid root maturation was paralleled by PEPC activation (e.g. reduced Km [PEP] coupled with elevated I50 [malate and Asp] values) via in vivo deubiquitination of p110 to p107, and subsequent phosphorylation of the deubiquitinated subunits. This novel mechanism of posttranslational control is hypothesized to contribute to the massive synthesis and excretion of organic acid anions that dominates the carbon metabolism of the mature proteoid roots. PMID:23407057

  10. Mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) and serine biosynthetic pathway genes are co-ordinately increased during anabolic agent-induced skeletal muscle growth

    PubMed Central

    Brown, D. M.; Williams, H.; Ryan, K. J. P.; Wilson, T. L.; Daniel, Z. C. T. R.; Mareko, M. H. D.; Emes, R. D.; Harris, D. W.; Jones, S.; Wattis, J. A. D.; Dryden, I. L.; Hodgman, T. C.; Brameld, J. M.; Parr, T.

    2016-01-01

    We aimed to identify novel molecular mechanisms for muscle growth during administration of anabolic agents. Growing pigs (Duroc/(Landrace/Large-White)) were administered Ractopamine (a beta-adrenergic agonist; BA; 20 ppm in feed) or Reporcin (recombinant growth hormone; GH; 10 mg/48 hours injected) and compared to a control cohort (feed only; no injections) over a 27-day time course (1, 3, 7, 13 or 27-days). Longissimus Dorsi muscle gene expression was analyzed using Agilent porcine transcriptome microarrays and clusters of genes displaying similar expression profiles were identified using a modified maSigPro clustering algorithm. Anabolic agents increased carcass (p = 0.002) and muscle weights (Vastus Lateralis: p < 0.001; Semitendinosus: p = 0.075). Skeletal muscle mRNA expression of serine/one-carbon/glycine biosynthesis pathway genes (Phgdh, Psat1 and Psph) and the gluconeogenic enzyme, phosphoenolpyruvate carboxykinase-M (Pck2/PEPCK-M), increased during treatment with BA, and to a lesser extent GH (p < 0.001, treatment x time interaction). Treatment with BA, but not GH, caused a 2-fold increase in phosphoglycerate dehydrogenase (PHGDH) protein expression at days 3 (p < 0.05) and 7 (p < 0.01), and a 2-fold increase in PEPCK-M protein expression at day 7 (p < 0.01). BA treated pigs exhibit a profound increase in expression of PHGDH and PEPCK-M in skeletal muscle, implicating a role for biosynthetic metabolic pathways in muscle growth. PMID:27350173

  11. Leaf P increase outpaces leaf N in an Inner Mongolia grassland over 27 years.

    PubMed

    Mi, Zhaorong; Huang, Yuanyuan; Gan, Huijie; Zhou, Wenjia; Flynn, Dan F B; He, Jin-Sheng

    2015-01-01

    The dynamics of leaf nitrogen (N) and phosphorus (P) have been intensively explored in short-term experiments, but rarely at longer timescales. Here, we investigated leaf N : P stoichiometry over a 27-year interval in an Inner Mongolia grassland by comparing leaf N : P concentration of 2006 with that of 1979. Across 80 species, both leaf N and P increased, but the increase in leaf N lagged behind that of leaf P, leading to a significant decrease in the N : P ratio. These changes in leaf N : P stoichiometry varied among functional groups. For leaf N, grasses increased, woody species tended to increase, whereas forbs showed no change. Unlike leaf N, leaf P of grasses and forbs increased, whereas woody species showed no change. Such changes may reflect N deposition and P release induced by soil acidification over the past decades. The interannual effect of precipitation may somewhat have reduced the soil available N, leading to the more modest increase of leaf N than of leaf P. Thus, leaf N : P stoichiometry significantly responded to long-term environmental changes in this temperate steppe, but different functional groups responded differently. Our results indicate that conclusions of plant stoichiometry under short-term N fertilization should be treated with caution when extrapolating to longer timescales. PMID:25589490

  12. Classification and quantification of leaf curvature

    PubMed Central

    Liu, Zhongyuan; Jia, Liguo; Mao, Yanfei; He, Yuke

    2010-01-01

    Various mutants of Arabidopsis thaliana deficient in polarity, cell division, and auxin response are characterized by certain types of leaf curvature. However, comparison of curvature for clarification of gene function can be difficult without a quantitative measurement of curvature. Here, a novel method for classification and quantification of leaf curvature is reported. Twenty-two mutant alleles from Arabidopsis mutants and transgenic lines deficient in leaf flatness were selected. The mutants were classified according to the direction, axis, position, and extent of leaf curvature. Based on a global measure of whole leaves and a local measure of four regions in the leaves, the curvature index (CI) was proposed to quantify the leaf curvature. The CI values accounted for the direction, axis, position, and extent of leaf curvature in all of the Arabidopsis mutants grown in growth chambers. Comparison of CI values between mutants reveals the spatial and temporal variations of leaf curvature, indicating the strength of the mutant alleles and the activities of the corresponding genes. Using the curvature indices, the extent of curvature in a complicated genetic background becomes quantitative and comparable, thus providing a useful tool for defining the genetic components of leaf development and to breed new varieties with leaf curvature desirable for the efficient capture of sunlight for photosynthesis and high yields. PMID:20400533

  13. Leaf Shape Recognition using Centroid Contour Distance

    NASA Astrophysics Data System (ADS)

    Hasim, Abdurrasyid; Herdiyeni, Yeni; Douady, Stephane

    2016-01-01

    This research recognizes the leaf shape using Centroid Contour Distance (CCD) as shape descriptor. CCD is an algorithm of shape representation contour-based approach which only exploits boundary information. CCD calculates the distance between the midpoint and the points on the edge corresponding to interval angle. Leaf shapes that included in this study are ellips, cordate, ovate, and lanceolate. We analyzed 200 leaf images of tropical plant. Each class consists of 50 images. The best accuracy is obtained by 96.67%. We used Probabilistic Neural Network to classify the leaf shape. Experimental results demonstrated the effectiveness of the proposed approach for shape recognition with high accuracy.

  14. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  15. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  16. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  17. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  18. 7 CFR 30.2 - Leaf tobacco.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... stemming, sweating or fermenting, and conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed...

  19. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  20. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  1. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  2. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  3. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471... REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is American Upland cotton which is lower in leaf grade than...

  4. 7 CFR 28.466 - Leaf Grade 6.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is within the range represented...

  5. 7 CFR 28.464 - Leaf Grade 4.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is within the range represented...

  6. 7 CFR 28.465 - Leaf Grade 5.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is within the range represented...

  7. 7 CFR 28.462 - Leaf Grade 2.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is within the range represented...

  8. 7 CFR 28.463 - Leaf Grade 3.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is within the range represented...

  9. 7 CFR 28.467 - Leaf Grade 7.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which is within the range represented...

  10. 7 CFR 28.461 - Leaf Grade 1.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is within the range represented...

  11. Wind-induced leaf transpiration

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Wei; Chu, Chia-Ren; Hsieh, Cheng-I.; Palmroth, Sari; Katul, Gabriel G.

    2015-12-01

    While the significance of leaf transpiration (fe) on carbon and water cycling is rarely disputed, conflicting evidence has been reported on how increasing mean wind speed (U) impacts fe from leaves. Here, conditions promoting enhancement or suppression of fe with increasing U for a wide range of environmental conditions are explored numerically using leaf-level gas exchange theories that combine a stomatal conductance model based on optimal water use strategies (maximizing the 'net' carbon gain at a given fe), energy balance considerations, and biochemical demand for CO2. The analysis showed monotonic increases in fe with increasing U at low light levels. However, a decline in modeled fe with increasing U were predicted at high light levels but only in certain instances. The dominant mechanism explaining this decline in modeled fe with increasing U is a shift from evaporative cooling to surface heating at high light levels. New and published sap flow measurements for potted Pachira macrocarpa and Messerschmidia argentea plants conducted in a wind tunnel across a wide range of U (2 - 8 m s-1) and two different soil moisture conditions were also employed to assess how fe varies with increasing U. The radiative forcing imposed in the wind tunnel was only restricted to the lower end of expected field conditions. At this low light regime, the findings from the wind tunnel experiments were consistent with the predicted trends.

  12. Chloroplast Response to Low Leaf Water Potentials

    PubMed Central

    Keck, R. W.; Boyer, J. S.

    1974-01-01

    Cyclic and noncyclic photophosphorylation and electron transport by photosystem 1, photosystem 2, and from water to methyl viologen (“whole chain”) were studied in chloroplasts isolated from sunflower (Helianthus annus L. var Russian Mammoth) leaves that had been desiccated to varying degrees. Electron transport showed considerable inhibition at leaf water potentials of −9 bars when the chloroplasts were exposed to an uncoupler in vitro, and it continued to decline in activity as leaf water potentials decreased. Electron transport by photosystem 2 and coupled electron transport by photosystem 1 and the whole chain were unaffected at leaf water potentials of −10 to −11 bars but became progressively inhibited between leaf water potentials of −11 and −17 bars. A low, stable activity remained at leaf water potentials below −17 bars. In contrast, both types of photophosphorylation were unaffected by leaf water potentials of −10 to −11 bars, but then ultimately became zero at leaf water potentials of −17 bars. Although the chloroplasts isolated from the desiccated leaves were coupled at leaf water potentials of −11 to −12 bars, they became progressively uncoupled as leaf water potentials decreased to −17 bars. Abscisic acid and ribonuclease had no effect on chloroplast photophosphorylation. The results are generally consistent with the idea that chloroplast activity begins to decrease at the same leaf water potentials that cause stomatal closure in sunflower leaves and that chloroplast electron transport begins to limit photosynthesis at leaf water potentials below about −11 bars. However, it suggests that, during severe desiccation, the limitation may shift from electron transport to photophosphorylation. PMID:16658727

  13. “Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

    PubMed Central

    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. PMID:24167510

  14. Leaf hydraulic conductance in relation to anatomical and functional traits during Populus tremula leaf ontogeny.

    PubMed

    Aasamaa, Krõõt; Niinemets, Ulo; Sõber, Anu

    2005-11-01

    Leaf hydraulic conductance (K(leaf)) and several characteristics of hydraulic architecture and physiology were measured during the first 10 weeks of leaf ontogeny in Populus tremula L. saplings growing under control, mild water deficit or elevated temperature conditions. During the initial 3 weeks of leaf ontogeny, most measured characteristics rapidly increased. Thereafter, a gradual decrease in K(leaf) was correlated with a decrease in leaf osmotic potential under all conditions, and with increases in leaf dry mass per area and bulk modulus of elasticity under mild water deficit and control conditions. From about Week 3 onward, K(leaf) was 33% lower in trees subjected to mild water deficit and 33% higher in trees held at an elevated temperature relative to control trees. Mild water deficit and elevated temperature treatment had significant and opposite effects on most of the other characteristics measured. The ontogenetic maximum in K(leaf) was correlated positively with the width of xylem conduits in the midrib, but negatively with the overall width of the midrib xylem, number of lateral ribs, leaf dry mass per area and bulk modulus of elasticity. The ontogenetic maximum in K(leaf) was also correlated positively with the proportion of intercellular spaces and leaf osmotic potential, but negatively with leaf thickness, volume of mesophyll cells and epidermis and number of cells per total mesophyll cell volume, the closest relationships being between leaf osmotic potential and number of cells per total mesophyll cell volume. It was concluded that differences in protoplast traits are more important than differences in xylem or parenchymal cell wall traits in determining the variability in K(leaf) among leaves growing under different environmental conditions. PMID:16105808

  15. The unique structural and biochemical development of single cell C4 photosynthesis along longitudinal leaf gradients in Bienertia sinuspersici and Suaeda aralocaspica (Chenopodiaceae)

    PubMed Central

    Koteyeva, Nuria K.; Voznesenskaya, Elena V.; Berry, James O.; Cousins, Asaph B.; Edwards, Gerald E.

    2016-01-01

    Temporal and spatial patterns of photosynthetic enzyme expression and structural maturation of chlorenchyma cells along longitudinal developmental gradients were characterized in young leaves of two single cell C4 species, Bienertia sinuspersici and Suaeda aralocaspica. Both species partition photosynthetic functions between distinct intracellular domains. In the C4-C domain, C4 acids are formed in the C4 cycle during capture of atmospheric CO2 by phosphoenolpyruvate carboxylase. In the C4-D domain, CO2 released in the C4 cycle via mitochondrial NAD-malic enzyme is refixed by Rubisco. Despite striking differences in origin and intracellular positioning of domains, these species show strong convergence in C4 developmental patterns. Both progress through a gradual developmental transition towards full C4 photosynthesis, with an associated increase in levels of photosynthetic enzymes. Analysis of longitudinal sections showed undeveloped domains at the leaf base, with Rubisco rbcL mRNA and protein contained within all chloroplasts. The two domains were first distinguishable in chlorenchyma cells at the leaf mid-regions, but still contained structurally similar chloroplasts with equivalent amounts of rbcL mRNA and protein; while mitochondria had become confined to just one domain (proto-C4-D). The C4 state was fully formed towards the leaf tips, Rubisco transcripts and protein were compartmentalized specifically to structurally distinct chloroplasts in the C4-D domains indicating selective regulation of Rubisco expression may occur by control of transcription or stability of rbcL mRNA. Determination of CO2 compensation points showed young leaves were not functionally C4, consistent with cytological observations of the developmental progression from C3 default to intermediate to C4 photosynthesis. PMID:26957565

  16. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  17. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  18. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  19. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  20. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  1. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections,...

  2. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of... 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,...

  3. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2351.) ... 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,...

  4. Evolutionary and Environmental Forces Sculpting Leaf Development.

    PubMed

    Chitwood, Daniel H; Sinha, Neelima R

    2016-04-01

    Leaf shape is spectacularly diverse. As a major component of plant architecture and an interface for light capture, gas exchange, and thermoregulation, the potential contributions of leaves to plant fitness are innumerable. Particularly because of their intimate association and interaction with the surrounding environment, both the plasticity of leaf shape during the lifetime of a plant and the evolution of leaf shape over geologic time are revealing with respect to leaf function. Leaf shapes arise within a developmental context that constrains both their evolution and environmental plasticity. Quantitative models capturing genetic diversity, developmental context, and environmental plasticity will be required to fully understand the evolution and development of leaf shape and its response to environmental pressures. In this review, we discuss recent literature demonstrating that distinct molecular pathways are modulated by specific environmental inputs, the output of which regulates leaf dissection. We propose a synthesis explaining both historical patterns in the paleorecord and conserved plastic responses in extant plants. Understanding the potential adaptive value of leaf shape, and how to molecularly manipulate it, will prove to be invaluable in designing crops optimized for future climates. PMID:27046820

  5. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco. ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture... Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS...

  6. Leaf litter decomposition in three Adirondack lakes

    SciTech Connect

    Francis, A.J.; Quinby, H.L.; Hendrey, G.R.; Hoogendyk, C.G.

    1983-04-01

    Decomposition of terrestrial leaf litter in three Adirondack lakes with water pH values approximately 5, 6, and 7 was studied. Litter bags containing leaves of American beech, sugar maple, red maple, leather leaf, and red spruce were placed in the lakes. Samples were removed periodically over a 3-year period and analyzed for loss in weight, changes in leaf surface area, carbon, nitrogen, and bacterial populations. The rate of decomposition of litter depended on the leaf species tested as well as on the lake water in which they were incubated. Of the five leaf species tested, red maple decomposed much faster and red spruce more slowly, i.e., red maple > sugar maple > beech > leather leaf > red spruce. Further, the data indicated that the rate of decomposition of the leaves differed among the lakes in the order Woods (pH approx. 5) < Sagamore (pH approx. 6) < Panther (pH approx. 7), and that the microbial colonization of some leaf species was affected. Accumulations of leaf litter in acid lakes due to reduction in microbial decomposition may affect nutrient recycling in lake ecosystems. 8 references, 4 tables.

  7. Leaf Histology--Two Modern Methods.

    ERIC Educational Resources Information Center

    Freeman, H. E.

    1984-01-01

    Two methods for examining leaf structure are presented; both methods involve use of "superglue." The first method uses the glue to form a thin, permanent, direct replica of a leaf surface on a microscope slide. The second method uses the glue to examine the three-dimensional structure of spongy mesophyll. (JN)

  8. Distribution of proteins similar to IIIManH and IIIManL of the Streptococcus salivarius phosphoenolpyruvate:mannose-glucose phosphotransferase system among oral and nonoral bacteria.

    PubMed Central

    Pelletier, M; Frenette, M; Vadeboncoeur, C

    1995-01-01

    In Streptococcus salivarius, the phosphoenolpyruvate (PEP):mannose-glucose phosphotransferase system, which concomitantly transports and phosphorylates mannose, glucose, fructose, and 2-deoxyglucose, is composed of the general energy-coupling proteins EI and HPr, the specific membrane-bound IIIMan, and two forms of a protein called IIIMan, with molecular weights of 38,900 (IIIManH) and 35,200 (IIIManL), that are found in the cytoplasm as well as associated with the membrane. Several lines of evidence suggest that IIIManH and/or IIIManL are involved in the control of sugar metabolism. To determine whether other bacteria possess these proteins, we tested for their presence in 28 oral streptococcus strains, 3 nonoral streptococcus strains, 2 lactococcus strains, 2 enterococcus strains, 2 bacillus strains, 1 lactobacillus strain, Staphylococcus aureus, and Escherichia coli. Three approaches were used to determine whether the IIIMan proteins were present in these bacteria: (i) Western blot (immunoblot) analysis of cytoplasmic and membrane proteins, using anti-IIIManH and anti-IIIManH rabbit polyclonal antibodies; (ii) analysis of PEP-dependent phosphoproteins by polyacrylamide gel electrophoresis; and (iii) inhibition by anti-IIIMan antibodies of the PEP-dependent phosphorylation of 2-deoxyglucose (a mannose analog) by crude cellular extracts. Only the species S. salivarius and Streptococcus vestibularis possessed the two forms of IIIMan. Fifteen other streptococcal species possessed one protein with a molecular weight between 35,200 and 38,900 that cross-reacted with both antibodies. In the case of 9 species, a protein possessing the same electrophoretic mobility was phosphorylated at the expense of PEP. No such phosphoprotein, however, could be detected in the other six species. A III(Man)-like protein with a molecular weight of 35,500 was also detected in Lactobacillus casei by Western blot experiments as well as by PEP-dependent phosphoprotein analysis, and a

  9. Confirmation and Elimination of Xylose Metabolism Bottlenecks in Glucose Phosphoenolpyruvate-Dependent Phosphotransferase System-Deficient Clostridium acetobutylicum for Simultaneous Utilization of Glucose, Xylose, and Arabinose▿†

    PubMed Central

    Xiao, Han; Gu, Yang; Ning, Yuanyuan; Yang, Yunliu; Mitchell, Wilfrid J.; Jiang, Weihong; Yang, Sheng

    2011-01-01

    Efficient cofermentation of d-glucose, d-xylose, and l-arabinose, three major sugars present in lignocellulose, is a fundamental requirement for cost-effective utilization of lignocellulosic biomass. The Gram-positive anaerobic bacterium Clostridium acetobutylicum, known for its excellent capability of producing ABE (acetone, butanol, and ethanol) solvent, is limited in using lignocellulose because of inefficient pentose consumption when fermenting sugar mixtures. To overcome this substrate utilization defect, a predicted glcG gene, encoding enzyme II of the d-glucose phosphoenolpyruvate-dependent phosphotransferase system (PTS), was first disrupted in the ABE-producing model strain Clostridium acetobutylicum ATCC 824, resulting in greatly improved d-xylose and l-arabinose consumption in the presence of d-glucose. Interestingly, despite the loss of GlcG, the resulting mutant strain 824glcG fermented d-glucose as efficiently as did the parent strain. This could be attributed to residual glucose PTS activity, although an increased activity of glucose kinase suggested that non-PTS glucose uptake might also be elevated as a result of glcG disruption. Furthermore, the inherent rate-limiting steps of the d-xylose metabolic pathway were observed prior to the pentose phosphate pathway (PPP) in strain ATCC 824 and then overcome by co-overexpression of the d-xylose proton-symporter (cac1345), d-xylose isomerase (cac2610), and xylulokinase (cac2612). As a result, an engineered strain (824glcG-TBA), obtained by integrating glcG disruption and genetic overexpression of the xylose pathway, was able to efficiently coferment mixtures of d-glucose, d-xylose, and l-arabinose, reaching a 24% higher ABE solvent titer (16.06 g/liter) and a 5% higher yield (0.28 g/g) compared to those of the wild-type strain. This strain will be a promising platform host toward commercial exploitation of lignocellulose to produce solvents and biofuels. PMID:21926197

  10. Impairment by interleukin 1 beta and tumour necrosis factor alpha of the glucagon-induced increase in phosphoenolpyruvate carboxykinase gene expression and gluconeogenesis in cultured rat hepatocytes.

    PubMed Central

    Christ, B; Nath, A

    1996-01-01

    The influence of the inflammatory mediators interleukin 1 beta (IL1 beta) and tumour necrosis factor alpha (TNF alpha) on the glucagon-induced expression of phosphoenolpyruvate carboxykinase (PCK) and on glucose formation via gluconeogenesis was investigated in cultured rat hepatocytes. Gene expression was monitored by determination of mRNA levels and of enzyme activity. Glucose formation was estimated with newly synthesized radioactive glucose derived from a radiolabelled lactate precursor. Glucagon (0.1 or 1 nM) induced PCK mRNA transiently to a maximum 2 h after its application. In the presence of recombinant human (rh) IL1 beta or rhTNF alpha the increase in PCK mRNA levels was totally inhibited at 0.1 nM glucagon, whereas at 1 nM glucagon the maximal increase was inhibited by only 25%. Glucagon (0.1 or 1 nM) induced PCK activity to a maximum after 4 h (4-fold and 6-fold over prestimulatory activity respectively). In the presence of rhIL1 beta or rhTNF alpha the maximal increase was inhibited by approx. 50%. Addition of rhIL1 beta or rhTNF alpha 2 h after glucagon, at the maximal glucagon-induced PCK mRNA levels, accelerated the decay of PCK mRNA. Glucagon (1 or 10 nM) [corrected] increased glucose formation from lactate by 1.3-fold and 1.7-fold respectively over unstimulated rates. In the presence of rhIL1 beta or rhTNF alpha this increase in glucose formation was inhibited by 60-90%. At 0.1 nM, glucagon doubled the intracellular cAMP concentration. This increase was prevented by rhIL1 beta or rhTNF alpha. At 1 nM, glucagon increased cAMP concentrations by 10-fold. In the presence of rhIL1 beta or rhTNF alpha this increase was inhibited by 70%. From the results it is suggested that rhIL1 beta and rhTNF alpha prevented glucagon-stimulated PCK gene expression and gluconeogenesis at least in part by inhibition of the glucagon-stimulated increase in cAMP concentrations. PMID:8947481

  11. Carbon Dioxide Fixation and Related Properties in Sections of the Developing Green Maize Leaf 1

    PubMed Central

    Perchorowicz, John T.; Gibbs, Martin

    1980-01-01

    Light and dark 14CO2 assimilation, pulse-chase (14CO2 followed by 12CO2) labeling experiments both in the light and in the dark, photorespiratory activity and some enzymes (ribulose 1,5-bisphosphate (RuBP) carboxylase, phosphoenolpyruvate (PEP) carboxylase, and NADP-malic enzyme) were followed in sections of 2.5 centimeters from the base (younger tissue) to the tip (oldest tissue) of the green maize leaf. Tissue was taken from the third leaf of 12- to 16-day-old plants consisting of sections 0 to 2.5 centimeters (base), 4.5 to 7.0 centimeters (center) and 9.0 to 11.5 centimeters (top) measured from the base. Some of these properties were also determined in the intact leaves of 4-day-old maize plants. Electron microscopy indicated a Kranz anatomy in all sections. Differentiation into mesophyll granal chloroplasts and bundle sheath agranal chloroplasts had taken place only in the center and top pieces. All of the sections contained PEP carboxylase, RuBP carboxylase, and NADP-malic enzyme. The ratio of PEP:RuBP carboxylase increased from 3.03 (top) to 4.66 (base) whereas the PEP carboxylase:NADP-malic enzyme ratio rose from 2.87 (top) to 9.57 (base). Under conditions of light or dark, the majority of the newly incorporated 14CO2 was found in malate and aspartate in all sections and in 4-day-old leaves. The 14C-labeling pattern typical of C4 plants was present in the center and top sections and to a lesser extent in the 4-day-old leaves. In the base tissue, the percentage of radioactivity in malate and aspartate remained relatively constant both during photosynthesis and pulse-chase experiments. In contrast, radioactivity in glycerate-3-phosphate decreased with time coupled to an increase in sugar phosphates. To account for the isotopic pattern in the base tissue, parallel fixation by PEP carboxylase and RuBP carboxylase was proposed with the photosynthetic carbon reduction cycle functioning to some extent independently within the bundle sheath chloroplasts. The

  12. Possible Roles of Strigolactones during Leaf Senescence

    PubMed Central

    Yamada, Yusuke; Umehara, Mikihisa

    2015-01-01

    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. PMID:27135345

  13. Inferring climate from angiosperm leaf venation networks.

    PubMed

    Blonder, Benjamin; Enquist, Brian J

    2014-10-01

    Leaf venation networks provide an integrative linkage between plant form, function and climate niche, because leaf water transport underlies variation in plant performance. Here, we develop theory based on leaf physiology that uses community-mean vein density to predict growing season temperature and atmospheric CO2 concentration. The key assumption is that leaf water supply is matched to water demand in the local environment. We test model predictions using leaves from 17 temperate and tropical sites that span broad climatic gradients. We find quantitative agreement between predicted and observed climate values. We also highlight additional leaf traits that may improve predictions. Our study provides a novel approach for understanding the functional linkages between functional traits and climate that may improve the reconstruction of paleoclimate from fossil assemblages. PMID:24725225

  14. 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.

    PubMed

    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. PMID:26852108

  15. Relating Stomatal Conductance to Leaf Functional Traits

    PubMed Central

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

    2015-01-01

    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

  16. A model for leaf initiation

    PubMed Central

    Abraham-Shrauner, Barbara; Pickard, Barbara G

    2011-01-01

    A biophysical model is proposed for how leaf primordia are positioned on the shoot apical
    meristem in both spiral and whorl phyllotaxes. Primordia are initiated by signals that propagate
    in the epidermis in both azimuthal directions away from the cotyledons or the most recently
    specified primordia. The signals are linear waves as inferred from the spatial periodicity of the
    divergence angle and a temporal periodicity. The periods of the waves, which represent actively
    transported auxin, are much smaller than the plastochron interval. Where oppositely directed
    waves meet at one or more angular positions on the periphery of the generative circle, auxin
    concentration builds and as in most models this stimulates local movement of auxin to
    underlying cells, where it promotes polarized cell division and expansion. For higher order
    spirals the wave model requires asymmetric function of auxin transport; that is, opposite wave
    speeds differ. An algorithm for determination of the angular positions of leaves in common leaf
    phyllotaxic configurations is proposed. The number of turns in a pattern repeat, number of leaves
    per level and per pattern repeat, and divergence angle are related to speed of auxin transport and
    radius of the generative circle. The rule for composition of Fibonacci or Lucas numbers
    associated with some phyllotaxes is discussed. A subcellular model suggests how the shoot
    meristem might specify either symmetric or asymmetric transport of auxin away from the
    forming primordia that produce it. Biological tests that could make or break the mathematical
    and molecular hypotheses are proposed. PMID:22212121

  17. Antimicrobial effect of Pistacia atlantica leaf extract

    PubMed Central

    Ali Roozegar, Mohamad; Azizi Jalilian, Farid; Reza Havasian, Mohamad; Panahi, Jafar; Pakzad, Iraj

    2016-01-01

    The antimicrobial effect of the mastic tree (Pistacia atlantica) under in vitro conditions has been reported. Therefore, it is of interest to evaluate the effect of the plant leaf extract (aqueous) on bacterial load in mouth and saliva. The leaf of the Pistacia atlantica plant was collected and cleaned, dried at 40⁰c and then powdered. The extraction was carried out using the maceration method in vacuum with the rotary evaporator device. Bacterial inhibition (Streptococcus species) by the leaf extract was studied using the disc diffusion and embedding sink diffusion methods. The values of MIC and MBC were determined. The collected data was further analyzed using t-test and repeated measure statistical tests. The disc diffusion technique showed a significant inhibitory effect for Pistacia atlantica leaf extract on S. mutans (ATCC 35668) and S. mitis (ATCC 49456) with inhibition zones of 19 and 25 millimeters, respectively. This is for the highest leaf extract concentration used in this study (p<0.01). The values of MIC and MBC for S.mutans was 60, 90 μg/ml and for S. mitis was 75, 110 μg/ml (p<0.01 significance). The leaf extract has no significant effect on S. salivarius (ATCC 13419). Thus, the antimicrobial properties of the aqueous leaf extract from Pistacia atlantica is demonstrated in this study. PMID:27212840

  18. Leaf wetness distribution within a potato crop

    NASA Astrophysics Data System (ADS)

    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.

  19. Lipidomics of tobacco leaf and cigarette smoke.

    PubMed

    Dunkle, Melissa N; Yoshimura, Yuta; t'Kindt, Ruben; Ortiz, Alexia; Masugi, Eri; Mitsui, Kazuhisa; David, Frank; Sandra, Pat; Sandra, Koen

    2016-03-25

    Detailed lipidomics experiments were performed on the extracts of cured tobacco leaf and of cigarette smoke condensate (CSC) using high-resolution liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-Q-TOF MS). Following automated solid-phase extraction (SPE) fractionation of the lipid extracts, over 350 lipids could be annotated. From a large-scale study on 22 different leaf samples, it was determined that differentiation based on curing type was possible for both the tobacco leaf and the CSC extracts. Lipids responsible for the classification were identified and the findings were correlated to proteomics data acquired from the same tobacco leaf samples. Prediction models were constructed based on the lipid profiles observed in the 22 leaf samples and successfully allowed for curing type classification of new tobacco leaves. A comparison of the leaf and CSC data provided insight into the lipidome changes that occur during the smoking process. It was determined that lipids which survive the smoking process retain the same curing type trends in both the tobacco leaf and CSC data. PMID:26585203

  20. Antimicrobial effect of Pistacia atlantica leaf extract.

    PubMed

    Ali Roozegar, Mohamad; Azizi Jalilian, Farid; Reza Havasian, Mohamad; Panahi, Jafar; Pakzad, Iraj

    2016-01-01

    The antimicrobial effect of the mastic tree (Pistacia atlantica) under in vitro conditions has been reported. Therefore, it is of interest to evaluate the effect of the plant leaf extract (aqueous) on bacterial load in mouth and saliva. The leaf of the Pistacia atlantica plant was collected and cleaned, dried at 40⁰c and then powdered. The extraction was carried out using the maceration method in vacuum with the rotary evaporator device. Bacterial inhibition (Streptococcus species) by the leaf extract was studied using the disc diffusion and embedding sink diffusion methods. The values of MIC and MBC were determined. The collected data was further analyzed using t-test and repeated measure statistical tests. The disc diffusion technique showed a significant inhibitory effect for Pistacia atlantica leaf extract on S. mutans (ATCC 35668) and S. mitis (ATCC 49456) with inhibition zones of 19 and 25 millimeters, respectively. This is for the highest leaf extract concentration used in this study (p<0.01). The values of MIC and MBC for S.mutans was 60, 90 μg/ml and for S. mitis was 75, 110 μg/ml (p<0.01 significance). The leaf extract has no significant effect on S. salivarius (ATCC 13419). Thus, the antimicrobial properties of the aqueous leaf extract from Pistacia atlantica is demonstrated in this study. PMID:27212840

  1. An Apparent Anomaly in Peanut Leaf Conductance

    PubMed Central

    Pallas, James E.

    1980-01-01

    Conductance to gaseous transfer is normally considered to be greater from the abaxial than from the adaxial side of a leaf. Measurements of the conductance to water vapor of peanut leaves (Arachis hypogaea L.) under well watered and stress conditions in a controlled environment, however, indicated a 2-fold higher conductance from the adaxial side of the leaf than from the abaxial. Studies of conductance as light level was varied showed an increase in conductance from either surface with increasing light level, but conductance was always greater from the adaxial surface at any given light level. In contrast, measurements of soybean (Glycine max [L.] Merr.) and snapbean (Phaseolus vulgaris L.) leaf conductance showed an approximate 2-fold greater conductance from the abaxial surface than from the adaxial. Approximately the same number of stomata were present on both peanut leaf surfaces and stomatal size was similar. Electron microscopic examination of peanut leaves did not reveal any major structural differences between stomata on the two surfaces that would account for the differences in conductance. Light microscope studies of leaf sections revealed an extensive network of bundle sheaths with achloraplastic bundle sheath extensions; the lower epidermis was lined with a single layer of large achloraplastic parenchyma cells. Measurements of net photosynthesis made on upper and lower leaf surfaces collectively and individually indicated that two-thirds of the peanut leaf's total net photosynthesis can be attributed to diffusion of CO2 through the adaxial leaf surface. Possibly the high photosynthetic efficiency of peanut cultivars as compared with certain other C3 species is associated with the greater conductance of CO2 through their upper leaf surfaces. Images PMID:16661294

  2. Global Climatic Controls On Leaf Size

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    Since the 1890s it's been known that the wet tropics harbour plants with exceptionally large leaves. Yet the observed latitudinal gradient of leaf size has never been fully explained: it is still unclear which aspects of climate are most important for understanding geographic trends in leaf size, a trait that varies many thousand-fold among species. The key is the leaf-to-air temperature difference, which depends on the balance of energy inputs (irradiance) and outputs (transpirational cooling, losses to the night sky). Smaller leaves track air temperatures more closely than larger leaves. Widely cited optimality-based theories predict an advantage for smaller leaves in dry environments, where transpiration is restricted, but are silent on the latitudinal gradient. We aimed to characterize and explain the worldwide pattern of leaf size. Across 7900 species from 651 sites, here we show that: large-leaved species predominate in wet, hot, sunny environments; smaller-leaved species typify hot, sunny environments only when arid; small leaves are required to avoid freezing in high latitudes and at high elevation, and to avoid overheating in dry environments. This simple pattern was unclear in earlier, more limited analyses. We present a simple but robust, fresh approach to energy-balance modelling for both day-time and night-time leaf-to-air temperature differences, and thus risk of overheating and of frost damage. Our analysis shows night-chilling is important as well as day-heating, and simplifies leaf temperature modelling. It provides both a framework for modelling leaf size constraints, and a solution to one of the oldest conundrums in ecology. Although the path forward is not yet fully clear, because of its role in controlling leaf temperatures we suggest that climate-related leaf size constraints could usefully feature in the next generation of land ecosystem models.

  3. Key Proliferative Activity in the Junction between the Leaf Blade and Leaf Petiole of Arabidopsis1[W][OA

    PubMed Central

    Ichihashi, Yasunori; Kawade, Kensuke; Usami, Takeshi; Horiguchi, Gorou; Takahashi, Taku; Tsukaya, Hirokazu

    2011-01-01

    Leaves are the most important, fundamental units of organogenesis in plants. Although the basic form of a leaf is clearly divided into the leaf blade and leaf petiole, no study has yet revealed how these are differentiated from a leaf primordium. We analyzed the spatiotemporal pattern of mitotic activity in leaf primordia of Arabidopsis (Arabidopsis thaliana) in detail using molecular markers in combination with clonal analysis. We found that the proliferative zone is established after a short interval following the occurrence of a rod-shaped early leaf primordium; it is separated spatially from the shoot apical meristem and seen at the junction region between the leaf blade and leaf petiole and produces both leaf-blade and leaf-petiole cells. This proliferative region in leaf primordia is marked by activity of the ANGUSTIFOLIA3 (AN3) promoter as a whole and seems to be differentiated into several spatial compartments: activities of the CYCLIN D4;2 promoter and SPATULA enhancer mark parts of it specifically. Detailed analyses of the an3 and blade-on-petiole mutations further support the idea that organogenesis of the leaf blade and leaf petiole is critically dependent on the correct spatial regulation of the proliferative region of leaf primordia. Thus, the proliferative zone of leaf primordia is spatially differentiated and supplies both the leaf-blade and leaf-petiole cells. PMID:21880932

  4. Evaluation of Methane from Sisal Leaf Residue and Palash Leaf Litter

    NASA Astrophysics Data System (ADS)

    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.

  5. Wheat leaf photosynthesis loss due to leaf rust, with respect to lesion development and leaf nitrogen status.

    PubMed

    Robert, Corinne; Bancal, Marie-Odile; Ney, Bertrand; Lannou, Christian

    2005-01-01

    In wheat (Triticum aestivum cv. Soissons) plants grown under three different fertilisation treatments, we quantified the effect of leaf rust (Puccinia triticina) on flag leaf photosynthesis during the whole sporulation period. Bastiaans' model: Y = (1 - x)beta was used to characterize the relationship between relative leaf photosynthesis (Y) and disease severity (x). The evolution of the different types of symptoms induced by the pathogen (sporulating, chlorotic and necrosed tissues) was evaluated using image analysis. The beta-values varied from 2 to 11, 1.4-2, and 0.8-1 during the sporulation period, when considering the proportion of sporulating, sporulating + necrotic, and total diseased area, respectively. Leaf nitrogen (N) content did not change the effect of the disease on host photosynthesis. We concluded that leaf rust has no global effect on the photosynthesis of the symptomless parts of the leaves and that the large range in the quantification of leaf rust effect on the host, which is found in the literature, can be accounted for by considering the different symptom types. We discuss how our results could improve disease assessments and damage prediction in a wheat crop. PMID:15720636

  6. Consequences of phosphoenolpyruvate:sugar phosphotranferase system and pyruvate kinase isozymes inactivation in central carbon metabolism flux distribution in Escherichia coli

    PubMed Central

    2012-01-01

    Background In Escherichia coli phosphoenolpyruvate (PEP) is a key central metabolism intermediate that participates in glucose transport, as precursor in several biosynthetic pathways and it is involved in allosteric regulation of glycolytic enzymes. In this work we generated W3110 derivative strains that lack the main PEP consumers PEP:sugar phosphotransferase system (PTS-) and pyruvate kinase isozymes PykA and PykF (PTS-pykA- and PTS-pykF-). To characterize the effects of these modifications on cell physiology, carbon flux distribution and aromatics production capacity were determined. Results When compared to reference strain W3110, strain VH33 (PTS-) displayed lower specific rates for growth, glucose consumption and acetate production as well as a higher biomass yield from glucose. These phenotypic effects were even more pronounced by the additional inactivation of PykA or PykF. Carbon flux analysis revealed that PTS inactivation causes a redirection of metabolic flux towards biomass formation. A cycle involving PEP carboxylase (Ppc) and PEP carboxykinase (Pck) was detected in all strains. In strains W3110, VH33 (PTS-) and VH35 (PTS-, pykF-), the net flux in this cycle was inversely correlated with the specific rate of glucose consumption and inactivation of Pck in these strains caused a reduction in growth rate. In the PTS- background, inactivation of PykA caused a reduction in Ppc and Pck cycling as well as a reduction in flux to TCA, whereas inactivation of PykF caused an increase in anaplerotic flux from PEP to OAA and an increased flux to TCA. The wild-type and mutant strains were modified to overproduce L-phenylalanine. In resting cells experiments, compared to reference strain, a 10, 4 and 7-fold higher aromatics yields from glucose were observed as consequence of PTS, PTS PykA and PTS PykF inactivation. Conclusions Metabolic flux analysis performed on strains lacking the main activities generating pyruvate from PEP revealed the high degree of

  7. Identification of an oxygen-responsive element in the 5'-flanking sequence of the rat cytosolic phosphoenolpyruvate carboxykinase-1 gene, modulating its glucagon-dependent activation.

    PubMed Central

    Bratke, J; Kietzmann, T; Jungermann, K

    1999-01-01

    The glucagon-stimulated transcription of the cytosolic phosphoenolpyruvate carboxykinase-1 (PCK1) gene is mediated by cAMP and positively modulated by oxygen in primary hepatocytes. Rat hepatocytes were transfected with constructs containing the first 2500, 493 or 281 bp of the PCK1 5'-flanking region in front of the chloramphenicol acetyltransferase (CAT) reporter gene. With all three constructs glucagon induced CAT activity with decreasing efficiency maximally under arterial pO2 and to about 65% under venous pO2. Rat hepatocytes were then transfected with constructs containing the first 493 bp of the PCK1 5'-flanking region in front of the luciferase (LUC) reporter gene, which were block-mutated at the CRE1 (cAMP-response element-1; -93/-86), putative CRE2 (-146/-139), promoter element (P) 1 (-118/-104), P2 (-193/-181) or P4 (-291/-273) sites. Glucagon induced LUC activity strongly when the P1 and P2 sites were mutated and weakly when the P4 site was mutated; induction of the P1, P2 and P4 mutants was positively modulated by the pO2. Glucagon also induced LUC activity strongly when the putative CRE2 site was altered; however, induction of the CRE2 mutant was not modulated by the pO2. Glucagon did not induce LUC activity when the CRE1 site was modified. These experiments suggested that the CRE1 but not the putative CRE2 was an essential site necessary for the cAMP-mediated PCK1 gene activation by glucagon and that the putative CRE2 site was involved in the oxygen-dependent modulation of PCK1 gene activation. To confirm these conclusions rat hepatocytes were transfected with simian virus 40 (SV40)-promoter-driven LUC-gene constructs containing three CRE1 sequences (-95/-84), three CRE2 sequences (-148/-137) or three CRE1 sequences plus two CRE2 sequences of the PCK1 gene in front of the SV40 promoter. Glucagon induced LUC activity markedly when the CRE1, but not when the CRE2, sites were in front of the SV40-LUC gene; however, induction of the (CRE1)3SV40-LUC

  8. Effect of herbivore damage on broad leaf motion in wind

    NASA Astrophysics Data System (ADS)

    Burnett, Nicholas; Kothari, Adit

    2015-11-01

    Terrestrial plants regularly experience wind that imposes aerodynamic forces on the plants' leaves. Passive leaf motion (e.g. fluttering) and reconfiguration (e.g. rolling into a cone shape) in wind can affect the drag on the leaf. In the study of passive leaf motion in wind, little attention has been given to the effect of herbivory. Herbivores may alter leaf motion in wind by making holes in the leaf. Also, a small herbivore (e.g. snail) on a leaf can act as a point mass, thereby affecting the leaf's motion in wind. Conversely, accelerations imposed on an herbivore sitting on a leaf by the moving leaf may serve as a defense by dislodging the herbivore. In the present study, we investigated how point masses (>1 g) and holes in leaves of the tuliptree affected passive leaf motion in turbulent winds of 1 and 5 m s-1. Leaf motion was unaffected by holes in the leaf surface (about 10% of leaf area), but an herbivore's mass significantly damped the accelerations of fluttering leaves. These results suggest that an herbivore's mass, but not the damage it inflicts, can affect leaf motion in the wind. Furthermore, the damping of leaf fluttering from an herbivore's mass may prevent passive leaf motions from being an effective herbivore defense.

  9. Simulating Leaf Area of Corn Plants at Contrasting Water Status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An exponential decay function was fitted with literature data to describe the decrease in leaf expansion rate as leaf water potential decreases. The fitted function was then applied to modify an existing leaf area simulation module in a soil-plant-atmosphere continuum model in order to simulate leaf...

  10. 7 CFR 29.3647 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic, narrow, 70..., medium body, close leaf structure, rough, lean in oil, dull finish, pale color intensity, inelastic... Leaf. Mature, heavy, close leaf structure, rough, lean in oil, dull finish, pale color...

  11. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... may be waste. H5F—Low Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure,...

  12. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... may be waste. H5F—Low Quality Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure,...

  13. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 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...

  14. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 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...

  15. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2010 CFR

    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...

  16. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 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...

  17. 7 CFR 30.31 - Classification of leaf tobacco.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 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...

  18. 7 CFR 28.517 - Leaf Grade No. 7.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 7. 28.517 Section 28.517 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.517 Leaf Grade No. 7. American Pima cotton which in leaf is inferior to...

  19. 7 CFR 28.514 - Leaf Grade No. 4.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 4. 28.514 Section 28.514 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall be American Pima cotton which...

  20. 7 CFR 28.513 - Leaf Grade No. 3.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 3. 28.513 Section 28.513 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall be American Pima cotton which...

  1. 7 CFR 28.511 - Leaf Grade No. 1.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 1. 28.511 Section 28.511 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall be American Pima cotton which...

  2. 7 CFR 28.516 - Leaf Grade No. 6.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 6. 28.516 Section 28.516 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall be American Pima cotton which...

  3. 7 CFR 28.512 - Leaf Grade No. 2.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 2. 28.512 Section 28.512 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall be American Pima cotton which...

  4. 7 CFR 28.515 - Leaf Grade No. 5.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf Grade No. 5. 28.515 Section 28.515 Agriculture..., TESTING, AND STANDARDS Standards Official Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall be American Pima cotton which...

  5. What Is a Leaf? An Online Tutorial and Tests

    ERIC Educational Resources Information Center

    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…

  6. Spectroscopic Measurement of Leaf Water Status

    NASA Technical Reports Server (NTRS)

    Goetz, Alexander F. H.; Boardman, Joseph W.

    1995-01-01

    A leaf drying experiment was carried out in the laboratory in which simultaneous spectral reflectance in the 350-2450 nm region, and leaf weights, were measured at 10 second intervals over a 40 minute period. As the leaf water weight dropped from approximately 60 to 38%. a nearly-linear rise in reflectance at all wavelengths beyond 1000 nm was observed. A principal components analysis of the time series of spectra in the 2000-2500 nm wavelength region showed that over 99% of the variance in the spectra, that were individually scaled to have a sum equal to that of the mean spectrum and subsequently mean corrected, was in the first component. This result shows that it is feasible to determine leaf water content remotely with an imaging spectrometer independent of the surface irradiance effects caused by topography.

  7. A hotspot model for leaf canopies

    NASA Technical Reports Server (NTRS)

    Jupp, David L. B.; Strahler, Alan H.

    1991-01-01

    The hotspot effect, which provides important information about canopy structure, is modeled using general principles of environmental physics as driven by parameters of interest in remote sensing, such as leaf size, leaf shape, leaf area index, and leaf angle distribution. Specific examples are derived for canopies of horizontal leaves. The hotspot effect is implemented within the framework of the model developed by Suits (1972) for a canopy of leaves to illustrate what might occur in an agricultural crop. Because the hotspot effect arises from very basic geometrical principles and is scale-free, it occurs similarly in woodlands, forests, crops, rough soil surfaces, and clouds. The scaling principles advanced are also significant factors in the production of image spatial and angular variance and covariance which can be used to assess land cover structure through remote sensing.

  8. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    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...

  9. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 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...

  10. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 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...

  11. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 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...

  12. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 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...

  13. The red edge of plant leaf reflectance

    NASA Technical Reports Server (NTRS)

    Horler, D. N. H.; Dockray, M.; Barber, J.

    1983-01-01

    A detailed study of the red edge spectral feature of green vegetation based on laboratory reflectance spectrophotometry is presented. A parameter lambda is defined as the wavelength is defined as the wavelength of maximum slope and found to be dependent on chlorophyll concentration. Species, development stage, leaf layering, and leaf water content of vegetation also influences lambda. The maximum slope parameter is found to be independent of simulated ground area coverage. The results are interpreted in terms of Beer's Law and Kubelka-Munk theory. The chlorophyll concentration dependence of lambda seems to be explained in terms of a pure absorption effect, and it is suggested that the existence of two lambda components arises from leaf scattering properties. The results indicate that red edge measurements will be valuable for assessment of vegetative chlorophyll status and leaf area index independently of ground cover variations, and will be particularly suitable for early stress detection.

  14. Reflectance model of a plant leaf

    NASA Technical Reports Server (NTRS)

    Kumar, R.; Silva, L.

    1973-01-01

    A light ray, incident at 5 deg to the normal, is geometrically plotted through the drawing of the cross section of a soybean leaf using Fresnel's Equations and Snell's Law. The optical mediums of the leaf considered for ray tracing are: air, cell sap, chloroplast, and cell wall. The above ray is also drawn through the same leaf cross section considering cell wall and air as the only optical mediums. The values of the reflection and transmission found from ray tracing agree closely with the experimental results obtained using a Beckman DK-2A Spectroreflectometer. Similarly a light ray, incident at about 60 deg to the normal, is drawn through the palisade cells of a soybean leaf to illustrate the pathway of light, incident at an oblique angle, through the palisade cells.

  15. Monitoring Air Quality with Leaf Yeasts.

    ERIC Educational Resources Information Center

    Richardson, D. H. S.; And Others

    1985-01-01

    Proposes that leaf yeast serve as quick, inexpensive, and effective techniques for monitoring air quality. Outlines procedures and provides suggestions for data analysis. Includes results from sample school groups who employed this technique. (ML)

  16. Photosynthesis and Respiration in Leaf Slices.

    ERIC Educational Resources Information Center

    Brown, Simon

    1998-01-01

    Demonstrates how leaf slices provide an inexpensive material for illustrating several fundamental points about the biochemistry of photosynthesis and respiration. Presents experiments that illustrate the effects of photon flux density and herbicides and carbon dioxide concentration. (DDR)

  17. Semi-Rolled Leaf2 modulates rice leaf rolling by regulating abaxial side cell differentiation.

    PubMed

    Liu, Xiaofei; Li, Ming; Liu, Kai; Tang, Ding; Sun, Mingfa; Li, Yafei; Shen, Yi; Du, Guijie; Cheng, Zhukuan

    2016-04-01

    Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe asrl2(semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function.SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1(SLL1)/ROLLED LEAF9(RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation. PMID:26873975

  18. Semi-Rolled Leaf2 modulates rice leaf rolling by regulating abaxial side cell differentiation

    PubMed Central

    Liu, Xiaofei; Li, Ming; Liu, Kai; Tang, Ding; Sun, Mingfa; Li, Yafei; Shen, Yi; Du, Guijie; Cheng, Zhukuan

    2016-01-01

    Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe a srl2 (semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function. SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1 (SLL1)/ROLLED LEAF9 (RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation. PMID:26873975

  19. Remote sensing of leaf water status

    NASA Technical Reports Server (NTRS)

    Ripple, William J.; Schrumpf, Barry J.

    1987-01-01

    Relative water content (RWC) measurements were made concurrently with spectral reflectance measurements from individual snapbean leaves. The relationships between spectra and RWC were described using second order polynomial equations. The middle infrared bands most sensitive to changes in leaf RWC also had the highest water absorption coefficients, as published by Curcio Petty (1951). The relationship between reflectance at 2100nm and total water potential for a single leaf was found to be linear.

  20. Wind increases leaf water use efficiency.

    PubMed

    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. PMID:26714739

  1. Leaf morphology shift linked to climate change

    PubMed Central

    Guerin, Greg R.; Wen, Haixia; Lowe, Andrew J.

    2012-01-01

    Climate change is driving adaptive shifts within species, but research on plants has been focused on phenology. Leaf morphology has demonstrated links with climate and varies within species along climate gradients. We predicted that, given within-species variation along a climate gradient, a morphological shift should have occurred over time due to climate change. We tested this prediction, taking advantage of latitudinal and altitudinal variations within the Adelaide Geosyncline region, South Australia, historical herbarium specimens (n = 255) and field sampling (n = 274). Leaf width in the study taxon, Dodonaea viscosa subsp. angustissima, was negatively correlated with latitude regionally, and leaf area was negatively correlated with altitude locally. Analysis of herbarium specimens revealed a 2 mm decrease in leaf width (total range 1–9 mm) over 127 years across the region. The results are consistent with a morphological response to contemporary climate change. We conclude that leaf width is linked to maximum temperature regionally (latitude gradient) and leaf area to minimum temperature locally (altitude gradient). These data indicate a morphological shift consistent with a direct response to climate change and could inform provenance selection for restoration with further investigation of the genetic basis and adaptive significance of observed variation. PMID:22764114

  2. Association of tomato leaf curl Sudan virus with leaf curl disease of tomato in Jeddah, Saudi Arabia.

    PubMed

    Sohrab, Sayed Sartaj; Yasir, Muhammad; El-Kafrawy, Sherif Ali; Abbas, Ayman T; Mousa, Magdi Ali Ahmed; Bakhashwain, Ahmed A

    2016-06-01

    Tomato is an important vegetable crop and its production is adversely affected by leaf curl disease caused by begomovirus. Leaf curl disease is a serious concern for tomato crops caused by begomovirus in Jeddah, Kingdom of Saudi Arabia. Tomato leaf curl disease has been shown to be mainly caused either by tomato leaf curl Sudan virus or tomato yellow leaf curl virus as well as tomato leaf curl Oman virus. Many tomato plants infected with monopartite begomoviruses were also found to harbor a symptom enhancing betasatellites. Here we report the association of tomato leaf curl Sudan virus causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia. The complete genome sequence analysis showed highest (99.9 %) identity with tomato leaf curl Sudan virus causing leaf curl disease in Arabian Peninsula. In phylogenetic relationships analysis, the identified virus formed closest cluster with tomato leaf curl Sudan virus. In recombination analysis study, the major parent was identified as tomato leaf curl Sudan virus. Findings of this study strongly supports the associated virus is a variant of tomato leaf curl Sudan virus causing disease in Sudan, Yemen and Arabian Peninsula. The betasatellites sequence analysis showed highest identity (99.8 %) with tomato leaf curl betasatellites-Amaranthus-Jeddah. The phylogenetic analysis result based on betasatellites formed closed cluster with tomato yellow leaf curl Oman betasatellites. The importance of these findings and occurrence of begomovirus in new geographic regions causing leaf curl disease of tomato in Jeddah, Kingdom of Saudi Arabia are discussed. PMID:27366765

  3. Combined effects of girdling and leaf removal on fluorescence characteristic of Alhagi sparsifolia leaf senescence.

    PubMed

    Tang, G; Li, X; Lin, L; Guo, H; Li, L

    2015-09-01

    Plant senescence is largely influenced by carbohydrate content. In order to investigate the impact of carbohydrate content on leaf senescence and photosystem II (PSII) during the senescence process, phloem girdling (PG), leaf removal (LR) and a combination of phloem girdling and leaf removal (GR) were performed on Alhagi sparsifolia (Fabaceae) at the end of the growing season. The results showed that during senescence, leaf soluble sugar content, starch content, the energy absorbed by the unit reaction centre (ABS/RC) increased; whereas, leaf photosynthetic rate, photosynthetic pigment content, maximum photochemical efficiency (φPo ) and energy used by the acceptor site in electron transfer (ETo/RC) decreased. The degree of change was PG > GR > CK (control) > LR. The results of the present work implied that phloem girdling (PG) significantly accelerated leaf senescence, and that single leaf removal (LR) slightly delayed leaf senescence; although leaf removal significantly delayed the senescence process on the girdled leaf (GR). Natural or delayed senescence only slightly inhibited the acceptor site of PSII and did not damage the donor site of PSII. On the other hand, induced senescence not only damaged the donor site of PSII (e.g. oxygen-evolving complex), but also significantly inhibited the acceptor site of PSII. In addition, leaf senescence led to an increase in the energy absorbed by the unit reaction centre (ABS/RC), which subsequently resulted in increasing excitation pressure in the reaction centre (DIo/RC), as well as additional saved Car for absorbing residual light energy and quenching reactive oxygen species during senescence. PMID:25662611

  4. Effects of crown development on leaf irradiance, leaf morphology and photosynthetic capacity in a peach tree.

    PubMed

    Walcroft, Adrian; Le Roux, Xavier; Diaz-Espejo, Antonio; Dones, Nicolas; Sinoquet, Hervé

    2002-09-01

    The three-dimensional (3-D) architecture of a peach tree (Prunus persica L. Batsch) growing in an orchard near Avignon, France, was digitized in April 1999 and again four weeks later in May 1999 to quantify increases in leaf area and crown volume as shoots developed. A 3-D model of radiation transfer was used to determine effects of changes in leaf area density and canopy volume on the spatial distribution of absorbed quantum irradiance (PAR(a)). Effects of changes in PAR(a) on leaf morphological and physiological properties were determined. Leaf mass per unit area (M(a)) and leaf nitrogen concentration per unit leaf area (N(a)) were both nonlinearly related to PAR(a), and there was a weak linear relationship between leaf nitrogen concentration per unit leaf mass (N(m)) and PAR(a). Photosynthetic capacity, defined as maximal rates of ribulose-1,5-bisphosphate carboxylase (Rubisco) carboxylation (V(cmax)) and electron transport (J(max)), was measured on leaf samples representing sunlit and shaded micro-environments at the same time that the tree crown was digitized. Both V(cmax) and J(max) were linearly related to N(a) during May, but not in April when the range of N(a) was low. Photosynthetic capacity per unit N(a) appeared to decline between April and May. Variability in leaf nitrogen partitioning between Rubisco carboxylation and electron transport was small, and the partitioning coefficients were unrelated to N(a). Spatial variability in photosynthetic capacity resulted from acclimation to varying PAR(a) as the crown developed, and acclimation was driven principally by changes in M(a) rather than the amount or partitioning of leaf nitrogen. PMID:12204849

  5. Molecular characterization of Chilli leaf curl virus and satellite molecules associated with leaf curl disease of Amaranthus spp.

    PubMed

    George, B; Kumar, R Vinoth; Chakraborty, S

    2014-04-01

    Amaranthus, collectively known as amaranth, is an annual or short-lived perennial plant used as leafy vegetables, cereals and for ornamental purposes in many countries including India. During 2011, leaf samples of Amaranthus plants displaying leaf curling, leaf distortion, leaf crinkling and yellow leaf margins were collected from Banswara district, Rajasthan in India. Full-length clones of a monopartite begomovirus, a betasatellite and an alphasatellite were characterized. The complete nucleotide sequence of the isolated begomovirus features as a typical 'Old World' begomovirus with the highest nucleotide per cent identity with Chilli leaf curl virus and hence, considered as an isolate of Chilli leaf curl virus. The complete nucleotide sequences of betasatellite and alphasatellite possess maximum nucleotide identity with Tomato yellow leaf curl Thailand betasatellite and Chilli leaf curl alphasatellite, respectively. This is the first report of the association of chilli-infecting begomovirus and satellite molecules infecting a new host, Amaranthus, causing leaf curl disease. PMID:24368759

  6. Complex regulation of the phosphoenolpyruvate carboxykinase gene pck and characterization of its GntR-type regulator IolR as a repressor of myo-inositol utilization genes in Corynebacterium glutamicum.

    PubMed

    Klaffl, Simon; Brocker, Melanie; Kalinowski, Jörn; Eikmanns, Bernhard J; Bott, Michael

    2013-09-01

    DNA affinity chromatography with the promoter region of the Corynebacterium glutamicum pck gene, encoding phosphoenolpyruvate carboxykinase, led to the isolation of four transcriptional regulators, i.e., RamA, GntR1, GntR2, and IolR. Determination of the phosphoenolpyruvate carboxykinase activity of the ΔramA, ΔgntR1 ΔgntR2, and ΔiolR deletion mutants indicated that RamA represses pck during growth on glucose about 2-fold, whereas GntR1, GntR2, and IolR activate pck expression about 2-fold irrespective of whether glucose or acetate served as the carbon source. The DNA binding sites of the four regulators in the pck promoter region were identified and their positions correlated with the predicted functions as repressor or activators. The iolR gene is located upstream and in a divergent orientation with respect to a iol gene cluster, encoding proteins involved in myo-inositol uptake and degradation. Comparative DNA microarray analysis of the ΔiolR mutant and the parental wild-type strain revealed strongly (>100-fold) elevated mRNA levels of the iol genes in the mutant, indicating that the primary function of IolR is the repression of the iol genes. IolR binding sites were identified in the promoter regions of iolC, iolT1, and iolR. IolR therefore is presumably subject to negative autoregulation. A consensus DNA binding motif (5'-KGWCHTRACA-3') which corresponds well to those of other GntR-type regulators of the HutC family was identified. Taken together, our results disclose a complex regulation of the pck gene in C. glutamicum and identify IolR as an efficient repressor of genes involved in myo-inositol catabolism of this organism. PMID:23873914

  7. An esterase gene from Lactobacillus casei cotranscribed with genes encoding a phosphoenolpyruvate:sugar phosphotransferase system and regulated by a LevR-like activator and sigma54 factor.

    PubMed

    Yebra, María J; Viana, Rosa; Monedero, Vicente; Deutscher, Josef; Pérez-Martínez, Gaspar

    2004-01-01

    A new esterase-encoding gene was found in the draft genome sequence of Lactobacillus casei BL23 (CECT5275). It is located in an operon together with genes encoding the EIIA, EIIB, EIIC, and EIID proteins of a mannose class phosphoenolpyruvate:sugar phosphotransferase system. After overproduction in Escherichia coli and purification, the esterase could hydrolyze acetyl sugars, hence the operon was named esu for esterase-sugar uptake genes. Upstream of the genes encoding the EII components (esuABCD) and the esterase (esuE), two genes transcribed in the opposite sense were found which encode a Bacillus subtilis LevR-like transcriptional activator (esuR) and a sigma54-like transcriptional factor (rpoN). As compared with the wild-type strain, elevated fructose phosphorylation was detected in L. casei mutants constitutively expressing the esu operon. However, none of the many sugars tested could induce the esu operon. The fact that EsuE exhibits esterase activity on acetyl sugars suggests that this operon could be involved in the uptake and metabolism of esterified sugars. Expression of the esu operon is similar to that of the B. subtilis lev operon: it contains a -12,-24 consensus promoter typical of sigma54-regulated genes, and EsuR and RpoN are essential for its transcription which is negatively regulated by EIIB(Esu). The esuABCDE transcription unit represents the first sigma54-regulated operon in lactobacilli. Furthermore, replacement of His852 in the phosphoenolpyruvate:sugar phosphotransferase system regulation domain II of EsuR with Ala indicated that the transcription activator function of EsuR is inhibited by EIIB(Esu)-mediated phosphorylation at His852. PMID:15925903

  8. Does leaf manipulation affect leaf appearance in italian ryegrass (Lolium multiflorum Lam.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mechanical stimuli such as rubbing, shaking, or flexing plants can alter their growth rates and morphologies. Plant response to mechanical stress can result in delayed plant growth, reduced leaf size, shorten and thicken stems, and reduced yields. Repeated measurements, such as leaf counting or me...

  9. Coming of leaf age: control of growth by hydraulics and metabolics during leaf ontogeny.

    PubMed

    Pantin, Florent; Simonneau, Thierry; Muller, Bertrand

    2012-10-01

    Leaf growth is the central process facilitating energy capture and plant performance. This is also one of the most sensitive processes to a wide range of abiotic stresses. Because hydraulics and metabolics are two major determinants of expansive growth (volumetric increase) and structural growth (dry matter increase), we review the interaction nodes between water and carbon. We detail the crosstalks between water and carbon transports, including the dual role of stomata and aquaporins in regulating water and carbon fluxes, the coupling between phloem and xylem, the interactions between leaf water relations and photosynthetic capacity, the links between Lockhart's hydromechanical model and carbon metabolism, and the central regulatory role of abscisic acid. Then, we argue that during leaf ontogeny, these interactions change dramatically because of uncoupled modifications between several anatomical and physiological features of the leaf. We conclude that the control of leaf growth switches from a metabolic to a hydromechanical limitation during the course of leaf ontogeny. Finally, we illustrate how taking leaf ontogeny into account provides insights into the mechanisms underlying leaf growth responses to abiotic stresses that affect water and carbon relations, such as elevated CO2, low light, high temperature and drought. PMID:22924516

  10. Estimating global specific leaf area from MODIS leaf area index and model-simulated foliage mass

    NASA Astrophysics Data System (ADS)

    Baruah, P. J.; Yasuoka, Y.; Ito, A.; Dye, D.

    2006-12-01

    Specific leaf area (SLA) is an important leaf trait that is universally correlated positively to leaf nitrogen, leaf turnover rates, relative growth rate and most importantly, photosynthetic capacity. Though SLA is genetically encoded, it is often spatially variable within a species and within a single biome due to variable environmental conditions. However, without a global SLA map, global ecosystem models that use SLA, generally fix a single value for a particular biome. In this study, we develop a methodology to estimate global SLA from a remote sensing-derived key ecosystem variable, leaf area index and foliage mass estimated by a terrestrial ecosystem model SimCYCLE. SimCYCLE uses climatic inputs, land-cover data and biomass-allocation to estimate leaf biomass in a process-based scheme. Model-estimated foliage mass and MODIS leaf area index are assumed to represent the most-accurate ground condition to estimate SLA for the entire globe at 0.5 degree resolution. Validation of estimated specific leaf area is done with a published field-sampled global dataset, and additional field-sampled SLA data collected from published literatures. The validation data is also used for rectification of unrealistic values of estimated SLA to produce a global SLA map, which we strongly believe, would be valuable to improve estimates of carbon dynamic across individual biomes upon assimilation with the ecosystem models.

  11. Leaf endophyte load and fungal garden development in leaf-cutting ants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Previous work has shown that leaf-cutting ants prefer to cut leaf material that is relatively low in fungal endophyte content. Such a 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 thei...

  12. Reaction of sorghum lines to zonate leaf spot and rough leaf spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abundant, frequent rains, along with humid and cloudy conditions during the early part of the 2015 growing season, provided conducive conditions for an unusually severe outbreak of zonate leaf spot and rough leaf spot in a block of sorghum lines at the Texas A&M AgriLife Research Farm, Burleson Coun...

  13. Measurement of leaf relative water content by infrared reflectance

    NASA Technical Reports Server (NTRS)

    Hunt, E. Raymond, Jr.; Rock, Barrett N.; Nobel, Park S.

    1987-01-01

    From basic considerations and Beer's law, a leaf water content index incorporating reflectances of wavelengths from 0.76 to 0.90 microns and from 1.55 to 1.75 microns was developed that relates leaf reflectance to leaf relative water content. For the leaf succulent, Agave deserti, the leaf water content index was not significantly different from the relative water content for either individual leaves or an entire plant. Also, the relative water contents of intact plants of Encelia farinosa and Hilaria rigida in the field were estimated by the leaf water content index; variations in the proportion of living to dead leaf area could cause large errors in the estimate of relative water content. Thus, the leaf water content index may be able to estimate average relative water content of canopies when TM4 and TM5 are measured at a known relative water content and fraction of dead leaf material.

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

    PubMed

    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. PMID:24123455

  15. The INDETERMINATE DOMAIN Protein BROAD LEAF1 Limits Barley Leaf Width by Restricting Lateral Proliferation.

    PubMed

    Jöst, Moritz; Hensel, Götz; Kappel, Christian; Druka, Arnis; Sicard, Adrien; Hohmann, Uwe; Beier, Sebastian; Himmelbach, Axel; Waugh, Robbie; Kumlehn, Jochen; Stein, Nils; Lenhard, Michael

    2016-04-01

    Variation in the size, shape, and positioning of leaves as the major photosynthetic organs strongly impacts crop yield, and optimizing these aspects is a central aim of cereal breeding [1, 2]. Leaf growth in grasses is driven by cell proliferation and cell expansion in a basal growth zone [3]. Although several factors influencing final leaf size and shape have been identified from rice and maize [4-14], what limits grass leaf growth in the longitudinal or transverse directions during leaf development remains poorly understood. To identify factors involved in this process, we characterized the barley mutant broad leaf1 (blf1). Mutants form wider but slightly shorter leaves due to changes in the numbers of longitudinal cell files and of cells along the leaf length. These differences arise during primordia outgrowth because of more cell divisions in the width direction increasing the number of cell files. Positional cloning, analysis of independent alleles, and transgenic complementation confirm that BLF1 encodes a presumed transcriptional regulator of the INDETERMINATE DOMAIN family. In contrast to loss-of-function mutants, moderate overexpression of BLF1 decreases leaf width below wild-type levels. A functional BLF1-vYFP fusion protein expressed from the endogenous promoter shows a dynamic expression pattern in the shoot apical meristem and young leaf primordia. Thus, we propose that the BLF1 gene regulates barley leaf size by restricting cell proliferation in the leaf-width direction. Given the agronomic importance of canopy traits in cereals, identifying functionally different BLF1 alleles promises to allow for the generation of optimized cereal ideotypes. PMID:26996502

  16. Computer vision cracks the leaf code.

    PubMed

    Wilf, Peter; Zhang, Shengping; Chikkerur, Sharat; Little, Stefan A; Wing, Scott L; Serre, Thomas

    2016-03-22

    Understanding the extremely variable, complex shape and venation characters of angiosperm leaves is one of the most challenging problems in botany. Machine learning offers opportunities to analyze large numbers of specimens, to discover novel leaf features of angiosperm clades that may have phylogenetic significance, and to use those characters to classify unknowns. Previous computer vision approaches have primarily focused on leaf identification at the species level. It remains an open question whether learning and classification are possible among major evolutionary groups such as families and orders, which usually contain hundreds to thousands of species each and exhibit many times the foliar variation of individual species. Here, we tested whether a computer vision algorithm could use a database of 7,597 leaf images from 2,001 genera to learn features of botanical families and orders, then classify novel images. The images are of cleared leaves, specimens that are chemically bleached, then stained to reveal venation. Machine learning was used to learn a codebook of visual elements representing leaf shape and venation patterns. The resulting automated system learned to classify images into families and orders with a success rate many times greater than chance. Of direct botanical interest, the responses of diagnostic features can be visualized on leaf images as heat maps, which are likely to prompt recognition and evolutionary interpretation of a wealth of novel morphological characters. With assistance from computer vision, leaves are poised to make numerous new contributions to systematic and paleobotanical studies. PMID:26951664

  17. BOREAS TE-9 NSA Leaf Chlorophyll Density

    NASA Technical Reports Server (NTRS)

    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).

  18. Stomatal Density Influences Leaf Water and Leaf Wax D/H Values in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Lee, H.; Feakins, S. J.; Sternberg, L. O.

    2014-12-01

    The hydrogen isotopic composition (δD) of plant leaf wax is a powerful tool to study the hydrology of past and present environments. The δD value of leaf waxes is known to primarily reflect the δD value of source water, modified by biological fractionations commonly summarized as the 'net or apparent' fractionation. It remains a challenge, however, to quantitatively relate the isotopic composition of the end product (wax) back to that of the precursor (water) because multiple isotope effects contributing to the net fractionation are not yet well understood. Transgenic variants have heretofore unexplored potential to isolate individual isotope effects. Here we report the first hydrogen isotopic measurements from transgenic Arabidopsis thaliana plants with calculations of leaf water enrichment, net and biosynthetic fractionation values from measured δD of plant waters and leaf wax n-alkanes. We employed transgenic Arabidopsis leaves, engineered to have different stomatal density, by differential expression of the stomatal growth hormone stomagen. Comparison of variants and wild types allow us to isolate the effects of stomatal density on leaf water and the net fractionation expressed by leaf wax biomarkers. Results show that transgenic leaves with denser pores have more enriched leaf water and leaf wax δD values than wild type and even more so than transgenic leaves with sparse stomata (difference of 10 ‰). Our findings that stomatal density controls leaf water and leaf wax δD values adds insights into the cause of variations in net fractionations between species, as well as suggesting that geological variations in stomatal density may modulate the sedimentary leaf wax δD record. In nature, stomatal density varies between species and environments, and all other factors being equal, this will contribute to variations in fractionations observed. Over geological history, lower stomatal densities occur at times of elevated pCO2; our findings predict reduced leaf

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Mueller matrix of a dicot leaf

    NASA Astrophysics Data System (ADS)

    Vanderbilt, Vern C.; Daughtry, Craig S. T.

    2012-06-01

    A better understanding of the information contained in the spectral, polarized bidirectional reflectance and transmittance of leaves may lead to improved techniques for identifying plant species in remotely sensed imagery as well as better estimates of plant moisture and nutritional status. Here we report an investigation of the optical polarizing properties of several leaves of one species, Cannabis sativa, represented by a 3x3 Mueller matrix measured over the wavelength region 400-2,400 nm. Our results support the hypothesis that the leaf surface alters the polarization of incident light - polarizing off nadir, unpolarized incident light, for example - while the leaf volume tends to depolarized incident polarized light.

  1. Leaf water absorption and desorption functions for three turfgrasses

    NASA Astrophysics Data System (ADS)

    Liang, Xi; Su, Derong; Yin, Shuxia; Wang, Zhi

    2009-09-01

    SummaryPlant leaf can absorb water when the leaf is in contact with water. This happens when the rainfall is intercepted by plant leaves, where the intercepted part of rain remains on the leaf surface. When the intercepted water is either absorbed or subsequently evaporated into the atmosphere, the plant leaves can dissipate water through the desorption process until the plant is dry or rewatered. In this paper, two symptomatic models in the form of exponential functions for leaf water absorption and leaf water desorption were derived and validated by experimental data using leaves of three turfgrasses (Tall fescue, Perennial ryegrass and Kentucky bluegrass). Both the models and measured data showed that the rate of leaf water absorption was high at the low initial leaf water content and then gradually leveled off toward the saturated leaf water content. The rate of leaf water desorption was high at the high initial leaf water content then decreased drastically over time toward zero. The different plant leaves showed different exponents and other parameters of the functions which indicate the difference of plant species. Both the absorption and desorption rates were relatively higher for the Kentucky bluegrass and lower for the Tall fescue and Perennial ryegrass. The concept of specific leaf area ( SLA) was used to understand the saturated leaf water content ( C s) of the three turfgrasses. Linear relationships were found between C s and SLA. The leaf water absorption and desorption functions are useful for deriving physiological parameters of the plant such as permanent wilting leaf water content, naturally irreducible leaf water content, exponential leaf water absorption coefficient, and exponential leaf desorption coefficient, as well as for evaluating the effects of rainfall interception on plant growth and water use efficiency.

  2. DIGITAL IMAGE ANALYSIS OF ZOSTERA MARINA LEAF INJURY

    EPA Science Inventory

    Current methods for assessing leaf injury in Zostera marina (eelgrass) utilize subjective indexes for desiccation injury and wasting disease. Because of the subjective nature of these measures, they are inherently imprecise making them difficult to use in quantifying complex leaf...

  3. Leaf Stomata as Bioindicators: Stimulating Student Research

    ERIC Educational Resources Information Center

    Case, Steven B.

    2006-01-01

    Stomata are the pores on leaves through which carbon dioxide, oxygen, and water vapor are exchanged with the atmosphere. Researchers have found that leaf stomatal densities change in response to several environmental variables, including humidity, light intensity, and atmospheric levels of carbon dioxide, a greenhouse gas (Van Der Burgh, Dilcher,…

  4. Simulation rice leaf reflectance and its inversion

    NASA Astrophysics Data System (ADS)

    Li, Yunmei; Ni, Shaoxiang; Huang, Jinfeng

    2003-06-01

    To improve our understanding of photon transporting inside leaves, and hence improve the accuracy of yield estimating and growth monitoring of rice by remotely sensed data, we simulated rice leaf reflectance by PROSPECT model. The experiment, which were referred to as the late rice experiment, were conducted at Zhejiang University in 1999 and 2000 with one species of rice (which is called Xiushui 63); In 1999 the rice was planted normally, but in 2000 it was fertilized in three different levels (low, medium and high). Leaf spectrum (reflectance and transmittance), biochemical concentration such as chlorophyll, protein, cellulose, lignin and water content, and leaf area were measured during the experiment. By the PROSPECT model, we simulated leaf reflectance on four days" data set in 1999 and one day"s data set of three fertilizations in 2000. The correlation coefficients between actual and simulated values are more than 0.995, the RMSE values are less than 0.0212. On the other hand, the model has been inversed to estimate chlorophyll concentration. Compared with actual value, the comparative errors are less than 10%.

  5. Leafminers help us understand leaf hydraulic design.

    PubMed

    Nardini, Andrea; Raimondo, Fabio; Lo Gullo, Maria A; Salleo, Sebastiano

    2010-07-01

    Leaf hydraulics of Aesculus hippocastanum L. were measured over the growing season and during extensive leaf mining by the larvae of an invasive moth (Cameraria ohridella Deschka et Dimic) that specifically destroy the palisade tissue. Leaves showed seasonal changes in hydraulic resistance (R(lamina)) which were related to ontogeny. After leaf expansion was complete, the hydraulic resistance of leaves and the partitioning of resistances between vascular and extra-vascular compartments remained unchanged despite extensive disruption of the palisade by leafminers (up to 50%). This finding suggests that water flow from the petiole to the evaporation sites might not directly involve the palisade cells. The analysis of the temperature dependence of R(lamina) in terms of Q(10) revealed that at least one transmembrane step was involved in water transport outside the leaf vasculature. Anatomical analysis suggested that this symplastic step may be located at the bundle sheath where the apoplast is interrupted by hydrophobic thickening of cell walls. Our findings offer some support to the view of a compartmentalization of leaves into well-organized water pools so that the transpiration stream would involve veins, bundle sheath and spongy parenchyma, while the palisade tissue would be largely by-passed with the possible advantage of protecting cells from short-term fluctuations in water status. PMID:20199625

  6. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    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 Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  7. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  8. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  9. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Definitions...

  10. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  11. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  12. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official...

  13. New leaf diseases of barley in Egypt.

    PubMed

    Mehiar, F F; El-Deen, E; Wasfy, H; El-Samra, I A

    1976-01-01

    Leaf diseases of barley were observed also in Egypt. From leaves of barley were isolated: Helminthosporium teres, H. gramineum, Stemphylium vesicarium, Alternaria triticina, Vlocladium chartarum, Acnemonium kiliense, Stemphylium spec. accompanied with the Pleospora stage. Inoculations on both attached and detached leaves showed that all the tested fungi were pathogenic, except Acremonium kiliense and Ulocladium chartarum. PMID:1037183

  14. Reactive oxygen species in leaf abscission signaling

    PubMed Central

    Sakamoto, Masaru; Munemura, Ikuko; Tomita, Reiko

    2008-01-01

    Reactive oxygen species (ROS) are produced in response to many environmental stresses, such as UV, chilling, salt and pathogen attack. These stresses also accompany leaf abscission in some plants, however, the relationship between these stresses and abscission is poorly understood. In our recent report, we developed an in vitro abscission system that reproduces stress-induced pepper leaf abscission in planta. Using this system, we demonstrated that continuous production of hydrogen peroxide (H2O2) is involved in leaf abscission signaling. Continuous H2O2 production is required to induce expression of the cell wall-degrading enzyme, cellulase and functions downstream of ethylene in abscission signaling. Furthermore, enhanced production of H2O2 occurs at the execution phase of abscission, suggesting that H2O2 also plays a role in the cell-wall degradation process. These data suggest that H2O2 has several roles in leaf abscission signaling. Here, we propose a model for these roles. PMID:19704438

  15. Bioinformatic pipelines in Python with Leaf

    PubMed Central

    2013-01-01

    Background An incremental, loosely planned development approach is often used in bioinformatic studies when dealing with custom data analysis in a rapidly changing environment. Unfortunately, the lack of a rigorous software structuring can undermine the maintainability, communicability and replicability of the process. To ameliorate this problem we propose the Leaf system, the aim of which is to seamlessly introduce the pipeline formality on top of a dynamical development process with minimum overhead for the programmer, thus providing a simple layer of software structuring. Results Leaf includes a formal language for the definition of pipelines with code that can be transparently inserted into the user’s Python code. Its syntax is designed to visually highlight dependencies in the pipeline structure it defines. While encouraging the developer to think in terms of bioinformatic pipelines, Leaf supports a number of automated features including data and session persistence, consistency checks between steps of the analysis, processing optimization and publication of the analytic protocol in the form of a hypertext. Conclusions Leaf offers a powerful balance between plan-driven and change-driven development environments in the design, management and communication of bioinformatic pipelines. Its unique features make it a valuable alternative to other related tools. PMID:23786315

  16. Toxicity evaluation of diazinon contaminated leaf litter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diazinon is an organophosphate pesticide with widespread use on a variety of agricultural crops. Because of its use, diazinon is a potential contributor to non-point source contamination of aquatic environments. A prominent feature within these aquatic environments includes leaf litter, especially...

  17. LONG LEAF PINE RESTORATION PROJECT MX974390

    EPA Science Inventory

    There are two primary goals for managing the Dantzler Coastal Preserve: 1) Protect and enhance the flora and fauna of the estuarine marsh; and 2) Manage the upland portion by restoring the long leaf pine ecosystem. Results from this project will improve the wetlands and water...

  18. Winter leaf reddening in 'evergreen' species.

    PubMed

    Hughes, Nicole M

    2011-05-01

    Leaf reddening during autumn in senescing, deciduous tree species has received widespread attention from the public and in the scientific literature, whereas leaf reddening in evergreen species during winter remains largely ignored. Winter reddening can be observed in evergreen herbs, shrubs, vines and trees in Mediterranean, temperate, alpine, and arctic regions, and can persist for several months before dissipating with springtime warming. Yet, little is known about the functional significance of this colour change, or why it occurs in some species but not others. Here, the biochemistry, physiology and ecology associated with winter leaf reddening are reviewed, with special focus on its possible adaptive function. Photoprotection is currently the favoured hypothesis for winter reddening, but alternative explanations have scarcely been explored. Intraspecific reddening generally increases with sunlight incidence, and may also accompany photosynthetic inferiority in photosynthetically 'weak' (e.g. low-nitrogen) individuals. Red leaves tend to show symptoms of shade acclimation relative to green, consistent with a photoprotective function. However, winter-red and winter-green species often cohabitate the same high-light environments, and exhibit similar photosynthetic capacities. The factors dictating interspecific winter leaf colouration therefore remain unclear. Additional outstanding questions and future directions are also highlighted, and possible alternative functions of winter reddening discussed. PMID:21375534

  19. Pharmacognostic evaluation of Cayratia trifolia (Linn.) leaf

    PubMed Central

    Kumar, Dinesh; Gupta, Jyoti; Kumar, Sunil; Arya, Renu; Kumar, Tarun; Gupta, Ankit

    2012-01-01

    Objective To present a detailed pharmacognostic study of the leaf of Cayratia trifolia (C. trifolia) Linn. (Vitaceae), an important plant in the Indian system of medicine. Methods The macroscopy, microscopy, physiochemical analysis, preliminary testing, fluorescence analysis of powder of the plant and other WHO recommended methods for standardization were investigated. Results Leaves are trifoliolated with petioles (2–3 cm) long. Leaflets are ovate to oblong-ovate, (2–8 cm) long, (1.5–5 cm) wide, pointed at the tip. The leaf surface shows the anisocytic type stomata covered with guard cells followed by epidermis layer. Leaf surface contents including veins, vein islet and vein termination were also determined. Transverse section of leaf shows the epidermis layer followed by cuticle layer and vascular bandles (xylem and phloem). The mesophyll is differentiated into palisade and spongy parenchyma. Abundant covering trichomes emerge from the upper epidermis. Trichomes are uniseriate and multicellular. Strips of collenchyma are present below and upper layer of epidermis. Conclusions It can be concluded that the pharmacognostic profile of the C. trifolia is helpful in developing standards for quality, purity and sample identification. PMID:23569825

  20. Aftereffects of low and high temperature pretreatment on leaf resistance, transpiration, and leaf temperature in xanthium.

    PubMed

    Drake, B G; Salisbury, F B

    1972-11-01

    Leaf resistance for water vapor (total diffusion resistance minus boundary layer resistance), transpiration, and leaf temperature were measured in attached leaves of greenhouse-grown Xanthium strumarium L. plants that had been pretreated for 72 hours with high (40 C day, 35 C night), or low (10 C day, 5 C night) air temperatures. Measurements were made in a wind tunnel at light intensity of 1.15 cal cm(-2) min(-1), air temperatures between 5 and 45 C, and wind speed of 65 cm sec(-1). Leaf resistances in low temperature pretreated plants were higher (8 to 27 sec cm(-1)) than in controls or high temperature pretreated plants (0.5 to 3 sec cm(-1)) at leaf temperatures between 5 and 25 C. Thus, the pretreatment influenced stomatal aperture. PMID:16658219

  1. A Journey Through a Leaf: Phenomics Analysis of Leaf Growth in Arabidopsis thaliana

    PubMed Central

    Vanhaeren, Hannes; Gonzalez, Nathalie; Inzé, Dirk

    2015-01-01

    In Arabidopsis, leaves contribute to the largest part of the aboveground biomass. In these organs, light is captured and converted into chemical energy, which plants use to grow and complete their life cycle. Leaves emerge as a small pool of cells at the vegetative shoot apical meristem and develop into planar, complex organs through different interconnected cellular events. Over the last decade, numerous phenotyping techniques have been developed to visualize and quantify leaf size and growth, leading to the identification of numerous genes that contribute to the final size of leaves. In this review, we will start at the Arabidopsis rosette level and gradually zoom in from a macroscopic view on leaf growth to a microscopic and molecular view. Along this journey, we describe different techniques that have been key to identify important events during leaf development and discuss approaches that will further help unraveling the complex cellular and molecular mechanisms that underlie leaf growth. PMID:26217168

  2. Relating Leaf Nitrogen, Leaf Photosynthesis and Canopy CO2 Exchange in a Temperate Winter Barley Field

    NASA Astrophysics Data System (ADS)

    Jensen, R.; Boegh, E.; Herbst, M.; Friborg, T.

    2012-12-01

    Net exchange of CO2 between the atmosphere and the soil-vegetation interface (NEE) is controlled by a wide range of biochemical and biophysical processes where leaf photosynthesis is often the most important. In mechanistically and physically based photosynthesis models (e.g. Farquhar et al. 1980) leaf nutrient status is a limiting factor for the photosynthetic capacity since it is implicitly incorporated through the parameters of maximum rate of carboxylation of CO2 (Vcmax) and the maximum rate of electron transport (Jmax). These are closely related to leaf nitrogen concentration (Na) and leaf chlorophyll content (Cab) and often show a characteristic seasonal dynamic. When simulating CO2 exchange, model outputs are sensitive to leaf photosynthetic capacity, which is labour consuming to verify through field measurements. A less time consuming method is to measure leaf "greenness" (SPAD), which is closely related to chlorophyll content and thus photosynthetic capacity. In the present study field measurements of leaf photosynthesis (LI-6400, LICOR Inc.), leaf reflectance (SPAD-502, Minolta), and LAI (LAI-2000, LICOR Inc.) were conducted on agricultural fields in Western Denmark during one growing season. The leaf photosynthesis measurements provided the basis for estimating photosynthetic capacity. SPAD measurements and LAI was measured with a higher spatial and temporal resolution. SPAD readings were calibrated against Cab and Na analyzed on leaf material in the laboratory and later correlated to photosynthetic capacity. These data were used to parameterize a coupled photosynthesis and stomatal model that was run for the growing season 2012 to estimate NEE. As a part of the hydrological observatory HOBE (hobe.dk), fluxes of greenhouse gasses are continuously measured by eddy covariance systems at three field sites in the Skjern River Catchment, Western Denmark, providing the basis for estimating the exchange of energy, water vapour, and CO2 on canopy scale. One of

  3. Leaf Areas And Spectral Properties Of Slash Pine

    NASA Technical Reports Server (NTRS)

    Curran, Paul J.; Dungan, Jennifer L.; Gholz, Henry L.

    1993-01-01

    NASA technical memorandum describes experiments to test feasibility of estimating seasonal leaf areas of forest canopies from spectral radiances measured by remote instruments. Accurate estimates of seasonal leaf areas of forests necessary for studies of seasonal exchanges of energy between forest canopies and atmosphere. Potential use of remote sensing in estimating seasonal changes in leaf area index (LAI).

  4. 7 CFR 29.2438 - Thin Leaf (C Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Fair Light-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak... Light-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak, dull... Medium-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak,...

  5. 7 CFR 29.2663 - Thin Leaf (C Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... tolerance. C4L Fair Light-brown Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull finish... Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull finish, pale color intensity, narrow... tolerance. C4F Fair Medium-brown Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull...

  6. OKRA-LEAF AS A POTENTIAL FOR WHITEFLY CONTROL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We compared smooth-leaf okra- and normal-leaf upland cotton (Gossypium hirsutum L.) cultivars for susceptibility to colonization by Bemisia tabaci (Gennadius) biotype B. Seven field studies were conducted, five at Holtville, CA and two at Maricopa, AZ during 1996 to 2000. Okra-leaf cultivars as a gr...

  7. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure, medium..., 70 percent; injury tolerance 30 percent, of which not over 10 percent may be waste. H6FR—Poor Quality... percent, of which not over 10 percent may be waste. H6K—Poor Quality Variegated Smoking Leaf Mellow,...

  8. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... over 10 percent may be waste. H6F—Poor Quality Orange Smoking Leaf Mellow, open leaf structure, medium..., 70 percent; injury tolerance 30 percent, of which not over 10 percent may be waste. H6FR—Poor Quality... percent, of which not over 10 percent may be waste. H6K—Poor Quality Variegated Smoking Leaf Mellow,...

  9. Turbine rotor-stator leaf seal and related method

    DOEpatents

    Herron, William Lee; Butkiewicz, Jeffrey John

    2003-01-01

    A seal assembly for installation between rotating and stationary components of a machine includes a first plurality of leaf spring segments secured to the stationary component in a circumferential array surrounding the rotating component, the leaf spring segments each having a radial mounting portion and a substantially axial sealing portion, the plurality of leaf spring segments shingled in a circumferential direction.

  10. 7 CFR 51.1220 - Leaf or limb rub injury.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Leaf or limb rub injury. 51.1220 Section 51.1220... STANDARDS) United States Standards for Grades of Peaches Definitions § 51.1220 Leaf or limb rub injury. “Leaf or limb rub injury” means that the scarring is not smooth, not light colored, or aggregates...

  11. Resistance to Cucurbit Leaf Crumple Virus in Melon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbit leaf crumple virus (CuLCrV) is a geminivirus common in melons (Cucumis melo L.) planted from July through September in the desert southwest U.S.A. Symptoms include chlorotic leaf spots and terminal buds, leaf curling and crumpling and interveinal yellowing, and plants may be stunted in size...

  12. Diel leaf growth of soybean: a novel method to analyze two-dimensional leaf expansion in high temporal resolution based on a marker tracking approach (Martrack Leaf)

    PubMed Central

    2013-01-01

    Background We present a novel method for quantitative analysis of dicot leaf expansion at high temporal resolution. Image sequences of growing leaves were assessed using a marker tracking algorithm. An important feature of the method is the attachment of dark beads that serve as artificial landmarks to the leaf margin. The beads are mechanically constricted to the focal plane of a camera. Leaf expansion is approximated by the increase in area of the polygon defined by the centers of mass of the beads surrounding the leaf. Fluctuating illumination conditions often pose serious problems for tracking natural structures of a leaf; this problem is circumvented here by the use of the beads. Results The new method has been used to assess leaf growth in environmental situations with different illumination conditions that are typical in agricultural and biological experiments: Constant illumination via fluorescent light tubes in a climate chamber, a mix of natural and artificial illumination in a greenhouse and natural illumination of the situation on typical summer days in the field. Typical features of diel (24h) soybean leaf growth patterns were revealed in all three conditions, thereby demonstrating the general applicability of the method. Algorithms are provided to the entire community interested in using such approaches. Conclusions The implementation Martrack Leaf presented here is a robust method to investigate diel leaf growth rhythms both under natural and artificial illumination conditions. It will be beneficial for the further elucidation of genotype x environment x management interactions affecting leaf growth processes. PMID:23883317

  13. [A inversion model for remote sensing of leaf water content based on the leaf optical property].

    PubMed

    Fang, Mei-hong; Ju, Wei-min

    2015-01-01

    Leaf water content is a fundamental physiological characteristic parameter of crops, and plays an important role in the study of the ecological environment. The aim of the work reported in this paper was to focus upon the retrieval of leaf water content from leaf-scale reflectance spectra by developing a physical inversion model based on the radiative transfer theory and wavelet analysis techniques. A continuous wavelet transform was performed on each of leaf component specific absorption coefficients to pick wavelet coefficients that were identified as highly sensitive to leaf water content and insensitive to other components. In the present study, for identifying the most appropriate wavelet, the six frequently used wavelet functions available within MATLAB were tested. Two biorl. 5 wavelet coefficients observed at the scale of 200 nm are provided with good performance, their wave-length positions are located at 1 405 and 1 488 nm, respectively. Two factors (α and Δ) of the predictive theoretical models based on the biorl. 5 wavelet coefficients of the leaf-scale reflectance spectra were determined by leaf structure parameter N. We built a database composed of thousands of simulated leaf reflectance spectra with the PROSPECT model. The entire dataset was split into two parts, with 60% the calibration subset assigned to calibrating two factors (α and Δ) of the predictive theoretical model. The remaining 40% the validation subset combined with the LOPEX93 experimental dataset used for validating the models. The results showed that the accuracy of the models compare to the statistical regression models derived from the traditional vegetation indices has improved with the highest predictive coefficient of determination (R2) of 0. 987, and the model becomes more robust. This study presented that wavelet analysis has the potential to capture much more of the information contained with reflectance spectra than previous analytical approaches which have tended to

  14. Prospect inversion for indirect estimation of leaf dry matter content and specific leaf area

    NASA Astrophysics Data System (ADS)

    Ali, A.; Darvishzadeh, R.; Skidmore, A.-K.; Duren, I.-V.; Heiden, U.; Heurich, M.

    2015-04-01

    Quantification of vegetation properties plays an indispensable role in assessments of ecosystem function with leaf dry mater content (LDMC) and specific leaf area (SLA) being two important vegetation properties. Methods for fast, reliable and accurate measurement of LDMC and SLA are still lacking. In this study, the inversion of the PROSPECT radiative transfer model was used to estimate these two leaf parameters. Inversion of PROSPECT traditionally aims at quantifying its direct input parameters rather than identifying the parameters which can be derived indirectly from the input parameters. The technique has been tested here to indirectly model these parameters for the first time. Biophysical parameters such as leaf area, as well as fresh and dry weights of 137 leaf samples were measured during a field campaign in July 2013 in the mixed mountain forests of the Bavarian Forest National Park, Germany. Reflectance and transmittance of the leaf samples were measured using an ASD field spec III equipped with an integrating sphere. The PROSPECT model was inverted using a look-up table (LUT) approach for the NIR/SWIR region of the spectrum. The retrieved parameters were evaluated using their calculated R2 and normalized root mean square error (nRMSE) values with the field measurements. 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. The results indicate that the leaf traits studied can be quantified as accurately as the direct input parameters of PROSPECT. 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 and in the landscape by using hyperspectral remote sensing data.

  15. An evolutionary perspective on leaf economics: phylogenetics of leaf mass per area in vascular plants.

    PubMed

    Flores, Olivier; Garnier, Eric; Wright, Ian J; Reich, Peter B; Pierce, Simon; Dìaz, Sandra; Pakeman, Robin J; Rusch, Graciela M; Bernard-Verdier, Maud; Testi, Baptiste; Bakker, Jan P; Bekker, Renée 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; Pérez-Harguindeguy, Natalia; Vendramini, Fernanda; Weiher, Evan

    2014-07-01

    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 construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes. PMID:25165520

  16. An evolutionary perspective on leaf economics: phylogenetics of leaf mass per area in vascular plants

    PubMed Central

    Flores, Olivier; Garnier, Eric; Wright, Ian J; Reich, Peter B; Pierce, Simon; Dìaz, Sandra; Pakeman, Robin J; Rusch, Graciela M; Bernard-Verdier, Maud; Testi, Baptiste; Bakker, Jan P; Bekker, Renée 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; Pérez-Harguindeguy, Natalia; Vendramini, Fernanda; Weiher, Evan

    2014-01-01

    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 construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes. PMID:25165520

  17. The maximum activities of hexokinase, phosphorylase, phosphofructokinase, glycerol phosphate dehydrogenases, lactate dehydrogenase, octopine dehydrogenase, phosphoenolpyruvate carboxykinase, nucleoside diphosphatekinase, glutamate-oxaloacetate transaminase and arginine kinase in relation to carbohydrate utilization in muscles from marine invertebrates.

    PubMed Central

    Zammit, V A; Newsholme, E A

    1976-01-01

    Comparison of the activities of hexokinase, phosphorylase and phosphofructokinase in muscles from marine invertebrates indicates that they can be divided into three groups. First, the activities of the three enzymes are low in coelenterate muscles, catch muscles of molluscs and muscles of echinoderms; this indicates a low rate of carbohydrate (and energy) utilization by these muscles. Secondly, high activities of phosphorylase and phosphofructokinase relative to those of hexokinase are found in, for example, lobster abdominal and scallop snap muscles; this indicates that these muscles depend largely on anaerobic degradation of glycogen for energy production. Thirdly, high activities of hexokinase are found in the radular muscles of prosobranch molluscs and the fin muscles of squids; this indicates a high capacity for glucose utilization, which is consistent with the high activities of enzymes of the tricarboxylic acid cycle in these muscles [Alp, Newsholme & Zammit (1976) Biochem. J. 154, 689-700]. 2. The activities of lactate dehydrogenase, octopine dehydrogenase, phosphoenolpyruvate carboxykinase, cytosolic and mitochondrial glycerol 3-phosphate dehydrogenase and glutamate-oxaloacetate transaminase were measured in order to provide a qualitative indication of the importance of different processes for oxidation of glycolytically formed NADH. The muscles are divided into four groups: those that have a high activity of lactate dehydrogenase relative to the activities of phosphofructokinase (e.g. crustacean muscles); those that have high activities of octopine dehydrogenase but low activities of lactate dehydrogenase (e.g. scallop snap muscle); those that have moderate activities of both lactate dehydrogenase and octopine dehydrogenase (radular muscles of prosobranchs), and those that have low activities of both lactate dehydrogenase and octopine dehydrogenase, but which possess activities of phosphoenolpyruvate carboxykinase (oyster adductor muscles). It is

  18. Genome-wide association study of rice (Oryza sativa L.) leaf traits with a high-throughput leaf scorer

    PubMed Central

    Yang, Wanneng; Guo, Zilong; Huang, Chenglong; Wang, Ke; Jiang, Ni; Feng, Hui; Chen, Guoxing; Liu, Qian; Xiong, Lizhong

    2015-01-01

    Leaves are the plant’s solar panel and food factory, and leaf traits are always key issues to investigate in plant research. Traditional methods for leaf trait measurement are time-consuming. In this work, an engineering prototype has been established for high-throughput leaf scoring (HLS) of a large number of Oryza sativa accessions. The mean absolute per cent of errors in traditional measurements versus HLS were below 5% for leaf number, area, shape, and colour. Moreover, HLS can measure up to 30 leaves per minute. To demonstrate the usefulness of HLS in dissecting the genetic bases of leaf traits, a genome-wide association study (GWAS) was performed for 29 leaf traits related to leaf size, shape, and colour at three growth stages using HLS on a panel of 533 rice accessions. Nine associated loci contained known leaf-related genes, such as Nal1 for controlling the leaf width. In addition, a total of 73, 123, and 177 new loci were detected for traits associated with leaf size, colour, and shape, respectively. In summary, after evaluating the performance with a large number of rice accessions, the combination of GWAS and high-throughput leaf phenotyping (HLS) has proven a valuable strategy to identify the genetic loci controlling rice leaf traits. PMID:25796084

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  20. Genome-wide association study of rice (Oryza sativa L.) leaf traits with a high-throughput leaf scorer.

    PubMed

    Yang, Wanneng; Guo, Zilong; Huang, Chenglong; Wang, Ke; Jiang, Ni; Feng, Hui; Chen, Guoxing; Liu, Qian; Xiong, Lizhong

    2015-09-01

    Leaves are the plant's solar panel and food factory, and leaf traits are always key issues to investigate in plant research. Traditional methods for leaf trait measurement are time-consuming. In this work, an engineering prototype has been established for high-throughput leaf scoring (HLS) of a large number of Oryza sativa accessions. The mean absolute per cent of errors in traditional measurements versus HLS were below 5% for leaf number, area, shape, and colour. Moreover, HLS can measure up to 30 leaves per minute. To demonstrate the usefulness of HLS in dissecting the genetic bases of leaf traits, a genome-wide association study (GWAS) was performed for 29 leaf traits related to leaf size, shape, and colour at three growth stages using HLS on a panel of 533 rice accessions. Nine associated loci contained known leaf-related genes, such as Nal1 for controlling the leaf width. In addition, a total of 73, 123, and 177 new loci were detected for traits associated with leaf size, colour, and shape, respectively. In summary, after evaluating the performance with a large number of rice accessions, the combination of GWAS and high-throughput leaf phenotyping (HLS) has proven a valuable strategy to identify the genetic loci controlling rice leaf traits. PMID:25796084

  1. Detecting Sugarcane yellow leaf virus infection in asymptomatic leaves with hyperspectral remote sensing and associated leaf pigment changes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarcane yellow leaf caused by Sugarcane yellow leaf virus (ScYLV) does not produce visual symptoms in most susceptible plants until late in the growing season. An experiment was conducted to determine if leaf reflectance and pigment analysis could be used to determine ScYLV infection prior to sym...

  2. Baby leaf lettuce germplasm enhancement: developing diverse populations with resistance to bacterial leaf spot caused by Xanthomonas campestris pv. vitians

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  3. Leaf nitrate assimilation during leaf expansion period: comparison of temperate and boreal tree species

    NASA Astrophysics Data System (ADS)

    Koyama, L.; Tokuchi, N.; Kielland, K.

    2011-12-01

    We examined nitrate assimilation in several tree species to test the hypothesis that plant N acquisition is highest in early spring due to the N demands of leaf growth and the seasonal availability of soil N. Specifically, we advance the idea that trees acquire N most actively during the leaf expansion period, which serves to offset growth-dilution of foliar N. However, it has been observed that boreal species expand their leaves more rapidly than do temperate species, suggesting that they exhibit a different seasonal pattern of N acquisition than do temperate species. To examine these relationships we measured leaf nitrate reductase activity (NRA) as a proxy for nitrate assimilation, leaf expansion rates, and foliar N concentrations on three boreal tree species and three temperate tree species throughout their leaf expansion period. An evergreen species (Quercus glauca) and two deciduous species (Acer palmatum and Zelkova serrata) were investigated in temperate Japan, and three deciduous species Alnus crispa, Betula papyrifera and Populus tremuloides were chosen in a boreal forest in interior Alaska, US. The patterns of foliar N concentrations were very similar across all six species, but the mean leaf expansion period was shorter in the boreal species (about 25 days) than in temperate species (about 29 days). All temperate species showed clear peaks of leaf NRA in the middle of leaf expansion period, suggesting that leaves partly compensate for the N dilution during expansion via foliar nitrate assimilation, and that plant nitrate acquisition was effectively timed to coincide with soil N availability generally increased in early spring. By contrast, peak NRA in the boreal species were observed in different stage of leaf expansion, but as in the temperate species declined to very low levels after the leaves were fully expanded. Our results demonstrate that plant nitrate assimilation is concentrated during leaf expansion in spring and early summer, but declines to

  4. The energetic and carbon economic origins of leaf thermoregulation.

    PubMed

    Michaletz, Sean T; Weiser, Michael D; McDowell, Nate G; Zhou, Jizhong; Kaspari, Michael; Helliker, Brent R; Enquist, Brian J

    2016-01-01

    Leaf thermoregulation has been documented in a handful of studies, but the generality and origins of this pattern are unclear. We suggest that leaf thermoregulation is widespread in both space and time, and originates from the optimization of leaf traits to maximize leaf carbon gain across and within variable environments. Here we use global data for leaf temperatures, traits and photosynthesis to evaluate predictions from a novel theory of thermoregulation that synthesizes energy budget and carbon economics theories. Our results reveal that variation in leaf temperatures and physiological performance are tightly linked to leaf traits and carbon economics. The theory, parameterized with global averaged leaf traits and microclimate, predicts a moderate level of leaf thermoregulation across a broad air temperature gradient. These predictions are supported by independent data for diverse taxa spanning a global air temperature range of ∼60 °C. Moreover, our theory predicts that net carbon assimilation can be maximized by means of a trade-off between leaf thermal stability and photosynthetic stability. This prediction is supported by globally distributed data for leaf thermal and photosynthetic traits. Our results demonstrate that the temperatures of plant tissues, and not just air, are vital to developing more accurate Earth system models. PMID:27548589

  5. Polarized and specular reflectance variation with leaf surface features

    NASA Technical Reports Server (NTRS)

    Grant, Lois; Daughtry, C. S. T.; Vanderbilt, V. C.

    1993-01-01

    The linearly polarized reflectance from a leaf depends on the characteristics of the leaf surface. In the present study the leaf reflectance of a number of plant species with varying surface characteristics was measured at the Brewster angle with a polarization photometer having 5 visible and near-infrared wavelength bands. We found that all leaf surfaces polarized incident light. Differences among species could be explained by variation in surface features. The results support our hypothesis that the polarized light is reflected by the leaf surface, not by its interior. Two mechanisms appeared responsible for the linearly polarized reflectance: (1) specular reflectance and (2) surface particle scattering. In most cases, large values of linearly polarized reflectance could be attributed to specular reflectance from the leaf surface. Attribution required knowledge of the optical dimensions of features on the leaf surface.

  6. Variations in the polarized leaf reflectance of Sorghum bicolor

    NASA Technical Reports Server (NTRS)

    Grant, Lois; Daughtry, C. S. T.; Vanderbilt, V. C.

    1987-01-01

    The polarized reflectance factor, Rq, of sorghum (Sorghum bicolor, L.) leaves from field-grown plants was measured in situ in the summers of 1983 and 1984. In 1983, three leaves of two randomly selected plants were measured at 2-week intervals. The value of Rq varied, depending on leaf and day of measurement. Measured values of Rq for the adaxial leaf surface ranged from 16 to 53; for the abaxial leaf surface the values ranged from 28 to 69. In 1984, measurements consisted of repeated observations made on the same leaf at biweekly intervals. The values of Rq from the adaxial leaf surface ranged from 26 to 38. Values of Rq from the abaxial leaf surface increased throughout the season, from 16 to 45. Differences in Rq were attributed to changes in surface details of the leaf.

  7. Use of NAP gene to manipulate leaf senescence in plants

    DOEpatents

    Gan, Susheng; Guo, Yongfeng

    2013-04-16

    The present invention discloses transgenic plants having an altered level of NAP protein compared to that of a non-transgenic plant, where the transgenic plants display an altered leaf senescence phenotype relative to a non-transgenic plant, as well as mutant plants comprising an inactivated NAP gene, where mutant plants display a delayed leaf senescence phenotype compared to that of a non-mutant plant. The present invention also discloses methods for delaying leaf senescence in a plant, as well as methods of making a mutant plant having a decreased level of NAP protein compared to that of a non-mutant plant, where the mutant plant displays a delayed leaf senescence phenotype relative to a non-mutant plant. Methods for causing precocious leaf senescence or promoting leaf senescence in a plant are also disclosed. Also disclosed are methods of identifying a candidate plant suitable for breeding that displays a delayed leaf senescence and/or enhanced yield phenotype.

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

    PubMed Central

    2012-01-01

    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. PMID:23140096

  9. Leaf-wax n-alkanes record the plant–water environment at leaf flush

    PubMed Central

    Tipple, Brett J.; Berke, Melissa A.; Doman, Christine E.; Khachaturyan, Susanna; Ehleringer, James R.

    2013-01-01

    Leaf-wax n-alkanes 2H/1H ratios are widely used as a proxy in climate reconstruction. Although the broad nature of the relationship between n-alkanes δ2H values and climate is appreciated, the quantitative details of the proxy remain elusive. To examine these details under natural environmental conditions, we studied a riparian broadleaf angiosperm species, Populus angustifolia, growing on water with a constant δ2H value and monitored the δ2H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout the entire growing season. Here we found the δ2H values of leaf-wax n-alkanes recorded only a 2-wk period during leaf flush and did not vary for the 19 weeks thereafter when leaves remained active. We found δ2H values of leaf-wax n-alkanes of P. angustifolia record conditions earlier in the season rather than fully integrating the entire growing season. Using these data, we modeled precipitation δ2H values during the time of wax synthesis. We observed that the isotope ratios of this precipitation generally were 2H-enriched compared with mean annual precipitation. This model provides a mechanistic basis of the often-observed 2H-enrichment from the expected fractionation values in studies of broadleaf angiosperm leaf-wax δ2H. In addition, these findings may have implications for the spatial and temporal uses of n-alkane δ2H values in paleoapplications; when both plant community and growth form are known, this study allows the isolation of the precipitation dynamics of individual periods of the growing season. PMID:23359675

  10. Effect of phosphorylation on hydrogen-bonding interactions of the active site histidine of the phosphocarrier protein HPr of the phosphoenolpyruvate-dependent phosphotransferase system determined by sup 15 N NMR spectroscopy

    SciTech Connect

    van Dijk, A.A.; de Lange, L.C.M.; Robillard, G.T. ); Bachovchin, W.W. )

    1990-09-04

    The phosphocarrier protein HPr of the phosphoenolpyruvate-dependent sugar transport system of Escherichia coli can exist in a phosphorylated and a nonphosphorylated form. During phosphorylation, the phosphoryl group is carried on a histidine residue, His15. The hydrogen-bonding state of this histidine was examined with {sup 15}N NMR. For this purpose we selectively enriched the histidine imidazole nitrogens with {sup 15}N by supplying an E. coli histidine auxotroph with the amino acid labeled either at the N{delta}1 and N{epsilon}2 positions or at only the N{delta}1 position. {sup 15}N NMR spectra of two synthesized model compound, phosphoimidazole and phosphomethylimidazole, were also recorded. The authors show that, prior to phosphorylation, the protonated His15 N{epsilon}2 is strongly hydrogen bonded, most probably to a carboxylate moiety. The H-bond should strengthen the nucleophilic character of the deprotonated N{delta}1, resulting in a good acceptor for the phosphoryl group. The hydrogen bond to the His15 N{delta}1 breaks upon phosphorylation of the residue. Implications of the H-bond structure for the mechanism of phosphorylation of HPr are discussed.

  11. Effect of phosphorylation on hydrogen-bonding interactions of the active site histidine of the phosphocarrier protein HPr of the phosphoenolpyruvate-dependent phosphotransferase system determined by 15N NMR spectroscopy.

    PubMed

    van Dijk, A A; de Lange, L C; Bachovchin, W W; Robillard, G T

    1990-09-01

    The phosphocarrier protein HPr of the phosphoenolpyruvate-dependent sugar transport system of Escherichia coli can exist in a phosphorylated and a nonphosphorylated form. During phosphorylation, the phosphoryl group is carried on a histidine residue, His15. The hydrogen-bonding state of this histidine was examined with 15N NMR. For this purpose we selectively enriched the histidine imidazole nitrogens with 15N by supplying an E. coli histidine auxotroph with the amino acid labeled either at the N delta 1 and N epsilon 2 positions or at only the N delta 1 position. 15N NMR spectra of two synthesized model compounds, phosphoimidazole and phosphomethylimidazole, were also recorded. We show that, prior to phosphorylation, the protonated His15 N epsilon 2 is strongly hydrogen bonded, most probably to a carboxylate moiety. The H-bond should strengthen the nucleophilic character of the deprotonated N delta 1, resulting in a good acceptor for the phosphoryl group. The hydrogen bond to the His15 N delta 1 breaks upon phosphorylation of the residue. Implications of the H-bond structure for the mechanism of phosphorylation of HPr are discussed. PMID:2261470

  12. Plant, cell, and molecular mechanisms of abscisic-acid regulation of stomatal apertures. In vivo phosphorylation of phosphoenolpyruvate carboxylase in guard cells of Vicia faba L. is enhanced by fusicoccin and suppressed by abscisic acid

    SciTech Connect

    Du, Z.; Aghoram, K.; Outlaw, W.H. Jr.

    1996-12-31

    Plants regulate water loss and CO{sub 2} gain by modulating the aperture sizes of stomata that penetrate the epidermis. Aperture size itself is increased by osmolyte accumulation and consequent turgor increase in the pair of guard cells that flank each stoma. Guard-cell phosphoenolpyruvate carboxylase, which catalyzes the regulated step leading to malate synthesis, is crucial for charge and pH maintenance during osmolyte accumulation. Regulation of this cytosolic enzyme by effectors is well documented, but additional regulation by posttranslational modification is predicted by the alteration of PEPC kinetics during stomatal opening. In this study, the authors have investigated whether this alteration is associated with the phosphorylation status of this enzyme. Using sonicated epidermal peels (isolated guard cells) pre-loaded with {sub 32}PO{sub 4}, the authors induced stomatal opening and guard-cell malate accumulation by incubation with 5 {micro}M fusicoccin (FC). In corroboratory experiments, guard cells were incubated with 5 {micro}M fusicoccin (FC). In corroboratory experiments, guard cells were incubated with the FC antagonist, 10 {micro}M abscisic acid (ABA). The phosphorylation status of PEPC was assessed by immunoprecipitation, electrophoresis, immunoblotting, and autoradiography. PEPC was phosphorylated when stomata were stimulated to open, and phosphorylation was lessened by incubation with ABA.

  13. 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

    PubMed Central

    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 thiobarbituric acid reactive substance and glutathione content) were determined. PEP (100 mM) significantly prevented an increase in LDH leakage, histological changes, such as tubulonecrosis and vacuolization, and changes in oxidative stress parameters during 72 h of cold preservation in mouse liver. Although glucose (100 mM) partly prevented LDH leakage and histological changes, no effects against oxidative stress were observed. By contrast, NAC inhibited oxidative stress in the liver and did not prevent LDH leakage or histological changes. PEP also significantly prevented kidney damage during cold preservation in a dose-dependent manner, and the protective effects were superior to those of glucose and NAC. We suggest that PEP, a functional carbohydrate with organ protective and antioxidative activities, may be useful as an organ preservation agent in clinical transplantation. PMID:24490082

  14. Aryl Hydrocarbon Receptor Activation by Dioxin Targets Phosphoenolpyruvate Carboxykinase (PEPCK) for ADP-ribosylation via 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-inducible Poly(ADP-ribose) Polymerase (TiPARP)*

    PubMed Central

    Diani-Moore, Silvia; Zhang, Sheng; Ram, Payal; Rifkind, Arleen B.

    2013-01-01

    Effects of the environmental toxin and carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) include a wasting syndrome associated with decreased gluconeogenesis. TCDD is a potent activator of the aryl hydrocarbon receptor (AHR), a ligand activated transcription factor. The relationship between gene activation by the AHR and TCDD toxicities is not well understood. We recently identified a pathway by which the AHR target gene TiPARP (TCDD-inducible poly(ADP-ribose) polymerase) contributes to TCDD suppression of transcription of phosphoenolpyruvate carboxykinase (PEPCK), a key regulator of gluconeogenesis, by consuming NAD+ and decreasing Sirtuin 1 activation of the peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α), a transcriptional activator of PEPCK. We report here that TCDD-induced TiPARP also targets PEPCK for ADP-ribosylation. Both cytosolic and mitochondrial forms of PEPCK were found to undergo ADP-ribosylation. Unexpectedly, AHR suppression also enhanced ADP-ribosylation and did so by a poly(ADP-ribose) polymerase-independent mechanism. This report 1) identifies ADP-ribosylation as a new posttranslational modification for PEPCK, 2) describes a pathway by which transcriptional induction of TiPARP by the AHR can lead to a downstream posttranslational change in a TCDD target protein (PEPCK), and 3) reveals that the AHR exerts complex, previously unidentified modulatory effects on ADP-ribosylation. PMID:23770670

  15. BOREAS TE-5 Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. The leaf photosynthetic gas exchange data were collected in the BOREAS NSA and the SSA from 06-Jun- 1994 to 13-Sep- 1994 using a LI-COR 6200 portable photosynthesis system. The data were collected to compare the photosynthetic capacity, stomata] conductance, and leaf intercellular CO, concentrations among the major tree species at the BOREAS sites. The data are average values from diurnal measurements on the upper canopy foliage (sun leaves). The data are available 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 Activity Archive Center (DAAC).

  16. Gravitropic basis of leaf blade nastic curvatures

    NASA Technical Reports Server (NTRS)

    Hayes, A. B.

    1982-01-01

    The curvatures produced in leaf blades by auxin treatment have been described as nastic curvatures because the initial differential growth is always enhanced on the lower side, regardless of the side of application. It is now known, however, that blades can show differential growth of either the upper or the lower side depending on the conditions of treatment. The dorsiventrality of the blade therefore influences but does not limit the direction of curvature. The dorsiventral directionality of response to growth regulators and the response to changes in the orientation to gravity are seen as indicating that blade curvatures are analogous to negative or positive gravitropism. It is noted that neither blade hyponasty or epinasty can be accounted for by ethylene alone. Petiole responses, however, are not directional, and the leaf angle changes induced by rotation or auxin treatment can be accounted for by ethylene production.

  17. BOREAS TE-5 Leaf Carbon Isotope Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Ehleriinger, Jim; Brooks, J. Renee; Flanagan, Larry

    2000-01-01

    The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This documentation describes leaf carbon isotope data that were collected in 1993 and 1994 at the NSA and SSA OJP sites, the SSA OBS site, and the NSA UBS site. In addition, leaf carbon isotope data were collected in 1994 only at the NSA and SSA OA sites. These data was collected to provide seasonal integrated physiological information for 10 to 15 common species at these 6 BOREAS sites. The data are stored 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).

  18. Toward Systems Understanding of Leaf Senescence: An Integrated Multi-Omics Perspective on Leaf Senescence Research.

    PubMed

    Kim, Jeongsik; Woo, Hye Ryun; Nam, Hong Gil

    2016-06-01

    Leaf senescence is a complex but tightly regulated developmental process involving a coordinated sequence of multiple molecular events, which ultimately leads to death of the leaf. Efforts to understand the mechanistic principles underlying leaf senescence have been largely made by transcriptomic, proteomic, and metabolomic studies over the past decade. This review focuses on recent milestones in leaf senescence research obtained using multi-omics technologies, as well as future endeavors toward systems understanding of leaf senescence processes. In particular, we discuss recent advances in understanding molecular events during leaf senescence through genome-wide transcriptome analyses in Arabidopsis. We also describe comparative transcriptome analyses used to unveil the commonality and diversity of regulatory mechanisms governing leaf senescence in the plant kingdom. Finally, we provide current illustrations of epigenomic, proteomic, and metabolomic landscapes of leaf senescence. We envisage that integration of multi-omics leaf senescence data will enable us to address unresolved questions regarding leaf senescence, including determining the molecular principles that coordinate concurrent and ordered changes in biological events during leaf senescence. PMID:27174403

  19. Yolk pigments of the Mexican leaf frog.

    PubMed

    Marinetti, G V; Bagnara, J T

    1983-02-25

    Eggs of the Mexican leaf frog contain blue and yellow pigments identified as biliverdin and lutein, respectively. Both pigments are bound to proteins that occur in crystalline form in the yolk platelet. The major blue pigment is biliverdin IX alpha. The eggs vary in color from brilliant blue to pale yellow-green depending on the amount of each pigment. These pigments may provide protective coloration to the eggs. PMID:6681678

  20. Vertical leaf pressure filter LVAzh 225

    SciTech Connect

    Fomichev, V.I.; Abramov, V.P.; Gutin, Y.V.

    1984-01-01

    A new vertical lead pressure filter LVAzh 225 has been developed with an arrangement for hydraulic coke removal. Industrial trials of the filter, however, showed the service life of the rubber seals of the butterfly valves to be short, so that butterfly valves were replaced by shut-off valves with a pneumatic drive. The prototype of the LVAzh 225 leaf filter has been recommended for series production.

  1. Simulating droplet motion on virtual leaf surfaces

    PubMed Central

    Mayo, Lisa C.; McCue, Scott W.; Moroney, Timothy J.; Forster, W. Alison; Kempthorne, Daryl M.; Belward, John A.; Turner, Ian W.

    2015-01-01

    A curvilinear thin film model is used to simulate the motion of droplets on a virtual leaf surface, with a view to better understand the retention of agricultural sprays on plants. The governing model, adapted from Roy et al. (2002 J. Fluid Mech. 454, 235–261 (doi:10.1017/S0022112001007133)) with the addition of a disjoining pressure term, describes the gravity- and curvature-driven flow of a small droplet on a complex substrate: a cotton leaf reconstructed from digitized scan data. Coalescence is the key mechanism behind spray coating of foliage, and our simulations demonstrate that various experimentally observed coalescence behaviours can be reproduced qualitatively. By varying the contact angle over the domain, we also demonstrate that the presence of a chemical defect can act as an obstacle to the droplet's path, causing break-up. In simulations on the virtual leaf, it is found that the movement of a typical spray size droplet is driven almost exclusively by substrate curvature gradients. It is not until droplet mass is sufficiently increased via coalescence that gravity becomes the dominating force. PMID:26064657

  2. Ancient pinnate leaf mimesis among lacewings

    PubMed Central

    Wang, Yongjie; Liu, Zhiqi; Wang, Xin; Shih, Chungkun; Zhao, Yunyun; Engel, Michael S.; Ren, Dong

    2010-01-01

    Insects have evolved diverse methods of predator avoidance, many of which implicate complex adaptations of their wings (e.g., Phylliidae, Nymphalidae, Notodontidae). Among these, angiosperm leaf mimicry is one of the most dramatic, although the historical origins of such modifications are unclear owing to a dearth of paleontological records. Here, we report evidence of pinnate leaf mimesis in two lacewings (Neuroptera): Bellinympha filicifolia Y. Wang, Ren, Liu & Engel gen. et sp. nov. and Bellinympha dancei Y. Wang, Ren, Shih & Engel, sp. nov., from the Middle Jurassic, representing a 165-million-year-old specialization between insects and contemporaneous gymnosperms of the Cycadales or Bennettitales. Furthermore, such lacewings demonstrate a preangiosperm origin for leaf mimesis, revealing a lost evolutionary scenario of interactions between insects and gymnosperms. The current fossil record suggests that this enigmatic lineage became extinct during the Early Cretaceous, apparently closely correlated with the decline of Cycadales and Bennettitales at that time, and perhaps owing to the changing floral environment resulted from the rise of flowering plants. PMID:20805491

  3. Stomatal Closure during Leaf Dehydration, Correlation with Other Leaf Physiological Traits1

    PubMed Central

    Brodribb, Tim J.; Holbrook, N. Michele

    2003-01-01

    The question as to what triggers stomatal closure during leaf desiccation remains controversial. This paper examines characteristics of the vascular and photosynthetic functions of the leaf to determine which responds most similarly to stomata during desiccation. Leaf hydraulic conductance (Kleaf) was measured from the relaxation kinetics of leaf water potential (Ψl), and a novel application of this technique allowed the response of Kleaf to Ψl to be determined. These “vulnerability curves” show that Kleaf is highly sensitive to Ψl and that the response of stomatal conductance to Ψl is closely correlated with the response of Kleaf to Ψl. The turgor loss point of leaves was also correlated with Kleaf and stomatal closure, whereas the decline in PSII quantum yield during leaf drying occurred at a lower Ψl than stomatal closure. These results indicate that stomatal closure is primarily coordinated with Kleaf. However, the close proximity of Ψl at initial stomatal closure and initial loss of Kleaf suggest that partial loss of Kleaf might occur regularly, presumably necessitating repair of embolisms. PMID:12913171

  4. Quantification of uncertainties in fossil leaf paleoaltimetry: Does leaf size matter?

    NASA Astrophysics Data System (ADS)

    Spicer, Robert A.; Yang, Jian

    2010-12-01

    The utility of multivariate foliar physiognomy, specifically the Climate Leaf Analysis Multivariate Program (CLAMP), to yield reliable estimates of enthalpy and, hence, paleoelevation has been demonstrated by comparison with other proxies, yet concerns have arisen regarding uncertainties arising from (1) apparent ambiguities in the scoring regime and (2) the way leaf size is scored. Regarding the first concern, scoring ambiguities are examined by reporting on scoring tests with novice users and interlaboratory comparisons. The uncertainties were found to be less than those arising from the statistical methodology underpinning CLAMP. In respect to the second concern, the effect of removing all size data both from modern test sites and fossil data was tested. Specifically, the effect of removing leaf size data from the 15 Ma Namling data set from south central Tibet was investigated. Removal of all size data from modern sites demonstrated that size data contributes little to estimates of mean annual temperature and enthalpy. Similarly, the removal of leaf size information from the Namling data set alone, but with calibration unchanged, and from both the Namling site and calibration sites, this time with recalibration, still yield paleoelevation estimates that have been independently matched by oxygen isotope techniques. Moreover, the removal of all leaf size information results in only small increases in uncertainty (±52 m).

  5. Leaf volatile emissions of Betula pendula during autumn coloration and leaf fall.

    PubMed

    Holopainen, Jarmo K; Heijari, Juha; Oksanen, Elina; Alessio, Giorgio A

    2010-10-01

    Deciduous trees remobilize the nitrogen in leaves during the process of autumn coloration, thus providing a high quality food source for aphids preparing to lay over-wintering eggs. It has been suggested that aphids may use volatile organic compounds (VOCs) to: (a) select leaves where nutrient remobilization has started and induced defenses are reduced; and (b) detect the time of leaf abscission. We analyzed VOCs emitted by the foliage of Betula pendula Roth. during autumn coloration and from leaf litter just after leaf fall. We tested the hypothesis that costly, photosynthesis-related terpenes and other herbivore-induced VOCs related to attraction of aphid parasitoids and predators are reduced during the coloration process. We also investigated if the VOC emission profile of abscising leaves is different from that of early stage yellowing leaves. Enemy-luring compounds (E)-β-ocimene, linalool, and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) were emitted only from the green foliage. Methyl salicylate (MeSa), known to recruit predatory bugs and attract migrant aphids, was emitted until the first stage of color change. Cis-3-hexenol, an indicator of cellular disintegration, became dominant in the emissions from abscising leaves and from fresh leaf litter. We discuss the ecological significance of the observed changes in birch leaf VOC profiles during the process of autumn senescence. PMID:20838885

  6. Photosynthetic responses to leaf surface wetness in tropical plant species of Costa Rica with varying leaf traits

    NASA Astrophysics Data System (ADS)

    Aparecido, L. M. T.; Moore, G. W.; Miller, G. R.; Cahill, A. T.

    2015-12-01

    Wet tropical forests are some of the environments with the greatest annual precipitation, but are also considered as the world's major carbon sink; however, literature postulates that phothsynthesis rates are inhibited while leaves are wet. Yet measurements of photosynthesis during wet conditions are challenging to obtain due to equipment limitations and the extreme complexity of canopy-atmosphere interactions in tropical environments. The objective of this study was to evaluate tropical species reactions to simulated leaf wetness and test the hypothesis that leaf wetness reduces rates of photosynthesis. In a central Costa Rica site with an average 4200 mm annual rainfall, we selected six tropical species with distinct leaf traits in which five sun-exposed leaf replicates from each species were subjected to gas exchange measurements using a LI-6400 IRGA (LICOR Inc., Lincoln, NE) under dry and wet/misted leaf conditions. Relationships between photosynthesis (As) and stomatal conductance (gs) with leaf to air temperature difference (DT), VPD, and relative humidity were evaluated using linear regression analysis. We found that the responses varied greatly among species, but all plants maintained a baseline of activity under wet leaf conditions, suggesting that abaxial leaf As was a significant percentage of total leaf As. Stachytarpheta jamaicens had an 18.7% reduction in As, while others, like Zamia skinneri, had a 7% increase in As. Tibouchina heteromalla showed a rapid stomatal recovery of 2 mins, while Carapa guianensis was slower with 7 mins. This variability between species suggests that leaf traits, such as presence or absence of trichomes, water repellency, vein distribution and size and leaf angle variation, may be critical for optimizing photosynthesis under wet conditions. Relative humidity and leaf temperature were the strongest secondary influences on As and gs under wet leaf conditions. While tropical vegetation-atmosphere interactions are complex, such

  7. Interaction between Silver Nanoparticles and Spinach Leaf

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

    2013-12-01

    Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. Cyto

  8. Using Leaf Samples to Establish a Library of Tropical Leaf Fingerprints

    NASA Astrophysics Data System (ADS)

    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.

  9. Stable isotopes in leaf water and transpiration - tools to assess leaf physiology and water uptake

    NASA Astrophysics Data System (ADS)

    Gessler, Arthur; Roddy, Adam; Volkmann, Till; Haberer, Kristine

    2014-05-01

    New laser based isotope technology allows online determination of the isotopic composition of water transpired from leaves. With this tool we can get new insights into leaf water physiology during day-night-cycles but also track the dynamics of plant water uptake with high temporal resolution. This talk we will give an overview on the following emerging topics - Leaf level physiology: The isotopic non-steady state of leaf water during the diel course - Plant-soil-atmosphere coupling: Dynamics of water uptake by plants Brought together both topics allow to get deeper insights into the effects of environmental parameters on the water balance of ecosystems bridging temporal and spatial scales. The findings from this research might help integrating plant physiological information, soil hydrological processes and the interaction between plant and soil processes in hydrological models.

  10. Leaf age dependent changes in within-canopy variation in leaf functional traits: a meta-analysis.

    PubMed

    Niinemets, Ülo

    2016-05-01

    Within-canopy variation in leaf structural and photosynthetic characteristics is a major means by which whole canopy photosynthesis is maximized at given total canopy nitrogen. As key acclimatory modifications, leaf nitrogen content (N A) and photosynthetic capacity (A A) per unit area increase with increasing light availability in the canopy and these increases are associated with increases in leaf dry mass per unit area (M A) and/or nitrogen content per dry mass and/or allocation. However, leaf functional characteristics change with increasing leaf age during leaf development and aging, but the importance of these alterations for within-canopy trait gradients is unknown. I conducted a meta-analysis based on 71 canopies that were sampled at different time periods or, in evergreens, included measurements for different-aged leaves to understand how within-canopy variations in leaf traits (trait plasticity) depend on leaf age. The analysis demonstrated that in evergreen woody species, M A and N A plasticity decreased with increasing leaf age, but the change in A A plasticity was less suggesting a certain re-acclimation of A A to altered light. In deciduous woody species, M A and N A gradients in flush-type species increased during leaf development and were almost invariable through the rest of the season, while in continuously leaf-forming species, the trait gradients increased constantly with increasing leaf age. In forbs, N A plasticity increased, while in grasses, N A plasticity decreased with increasing leaf age, reflecting life form differences in age-dependent changes in light availability and in nitrogen resorption for growth of generative organs. Although more work is needed to improve the coverage of age-dependent plasticity changes in some plant life forms, I argue that the age-dependent variation in trait plasticity uncovered in this study is large enough to warrant incorporation in simulations of canopy photosynthesis through the growing period. PMID

  11. Landmark Analysis Of Leaf Shape Using Polygonal Approximation

    NASA Astrophysics Data System (ADS)

    Firmansyah, Zakhi; Herdiyeni, Yeni; Paruhum Silalahi, Bib; Douady, Stephane

    2016-01-01

    This research proposes a method to extract landmark of leaf shape using static threshold of polygonal approximation. Leaf shape analysis has played a central role in many problems in vision and perception. Landmark-based shape analysis is the core of geometric morphometric and has been used as a quantitative tool in evolutionary and developmental biology. In this research, the polygonal approximation is used to select the best points that can represent the leaf shape variability. We used a static threshold as the control parameter of fitting a series of line segment over a digital curve of leaf shape. This research focuses on seven leaf shape, i.e., eliptic, obovate, ovate, oblong and special. Experimental results show static polygonal approximation shows can be used to find the important points of leaf shape.

  12. Endophytic fungi reduce leaf-cutting ant damage to seedlings

    PubMed Central

    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

  13. From genes to shape: regulatory interactions in leaf development.

    PubMed

    Barkoulas, Michalis; Galinha, Carla; Grigg, Stephen P; Tsiantis, Miltos

    2007-12-01

    In the past two years novel connections were described between auxin function and transcription factor patterning systems involved in both leaf initiation and elaboration of leaf axial patterning. A cascade of small RNA-based regulatory steps was suggested to facilitate delimitation of cell types comprising the upper versus lower parts of the leaf. Developmental regulation of cellular growth emerged as a crucial component in regulation of leaf form with TCP and CUC2 transcription factors playing a key role in this process. Finally, cis-regulatory evolution of developmental genes emerged as a process that likely contributed to diversification of leaf form, while studies in seedless land plants have begun to elucidate the ancestral and derived aspects of leaf development pathways. PMID:17869569

  14. Generality of leaf trait relationships: A test across six biomes

    SciTech Connect

    Reich, P.B.; Ellsworth, D.S.; Walters, M.B.; Vose, J.M.; Gresham, C.; Volin, J.C.; Bowman, W.D. |

    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.

  15. Biometamaterials: Black Ultrathin Gold Film Fabricated on Lotus Leaf.

    PubMed

    Ebihara, Yuusuke; Ota, Ryoichi; Noriki, Takahiro; Shimojo, Masayuki; Kajikawa, Kotaro

    2015-01-01

    We report on a black metamaterial of gold fabricated on a lotus leaf that was used as a template. In spite of the extremely thin gold coating (10-nm thick) on the lotus leaf, the surface shows reflectivity below 0.01 over the entire visible spectral range. Finite-difference time-domain (FDTD) calculations suggest that the low reflectivity stems from the secondary structures on the lotus leaf, where randomly oriented nanorods are distributed. PMID:26530514

  16. Biometamaterials: Black Ultrathin Gold Film Fabricated on Lotus Leaf

    PubMed Central

    Ebihara, Yuusuke; Ota, Ryoichi; Noriki, Takahiro; Shimojo, Masayuki; Kajikawa, Kotaro

    2015-01-01

    We report on a black metamaterial of gold fabricated on a lotus leaf that was used as a template. In spite of the extremely thin gold coating (10-nm thick) on the lotus leaf, the surface shows reflectivity below 0.01 over the entire visible spectral range. Finite-difference time-domain (FDTD) calculations suggest that the low reflectivity stems from the secondary structures on the lotus leaf, where randomly oriented nanorods are distributed. PMID:26530514

  17. Ozone-induced ethylene release from leaf surfaces

    SciTech Connect

    Rodecap, K.D.; Tingey, D.T.

    1986-01-01

    Ozone-induced stress-ethylene emissions from the adaxial and abaxial leaf surfaces of four plant species (Glycine max (L) Merr. cv. Dare, Lycopersicon esculentum Mill cv. Roma VF, Eucalyptus globulus Labill. and Hedera helix L.) were studied to determine if the stress ethylene diffused through the stomata or cuticle. In plants not exposed to ozone, basal ethylene was detected above both the adaxial and abaxial leaf surfaces of all the plant species examined, indicating that some ethylene can diffuse across the leaf cuticle. Oxone-induced stress ethylene production in all species examined. These data indicate that ozone-induced stress ethylene primarily diffuses from the leaf via the stomata.

  18. Global Patterns in Leaf Respiration and its Temperature Response

    NASA Astrophysics Data System (ADS)

    Heskel, M.; Atkin, O. K.; O'Sullivan, O. S.; Reich, P. B.; Tjoelker, M. G.; Weerasinghe, L. K.; Penillard, A.; Egerton, J. J. G.; Creek, D.; Bloomfield, K. J.; Xiang, J.; Sinca, F.; Stangl, Z.; Martinez-de la Torre, A.; Griffin, K. L.; Huntingford, C.; Hurry, V.; Meir, P.; Turnbull, M.

    2015-12-01

    Leaf respiration (R) represents a massive flux of carbon to the atmosphere. Currently, neither physiological models nor terrestrial biosphere models are able to disentangle sources of variation in leaf R among different plant species and contrasting environments. Similarly, such models do not adequately describe the short-term temperature (T) response of R, which can lead to inaccurate representation of leaf R in simulation models of regional and global terrestrial carbon cyling. Even minor differences in the underlying basal rate of leaf R and/or shape of the T-response curve can significantly impact estimates of carbon released and stored in ecosystems. Given this, we recently assembled and analyzed two new global databases (arctic-to-tropics) of leaf R and its short-term T-dependence. The results highlight variation in basal leaf R among species and across global gradients in T and aridity, with leaf R at a standard T (e.g. 25°C) being greatest in plants growing in the cold, dry Arctic and lowest in the warm, moist tropics. Arctic plants also exhibit higher rates of leaf R at a given photosynthetic capacity or leaf N concentration than their tropical counterparts. The results also point to convergence in the short-term temperature response of respiration across biomes and plant functional types. The applicability and significance of the short-term T-response of R for simulation models of plant and ecosystem carbon fluxes will be discussed.

  19. Further Studies of the Heat Transfer from a Leaf

    PubMed Central

    Linacre, E. T.

    1967-01-01

    The resistance to the diffusion of heat and water vapor external to a leaf, can be derived from measurement of the rate of change of the leaf temperature, after a sudden alteration of the intensity of irradiation. The theory of the method has been developed to accommodate the case of a leaf that is freely transpiring, exchanging longwave radiation with the environment and with different internal resistances on the 2 sides of the leaf. It has been successfully applied to measurements on wet blotting paper in the laboratory. PMID:16656550

  20. Short Interval Leaf Movements of Cotton 12

    PubMed Central

    Miller, Charles S.

    1975-01-01

    Gossypium hirsutum L. cv. Lankart plants exhibited three different types of independent short interval leaf movements which were superimposed on the circadian movements. The different types were termed SIRV (short interval rhythmical vertical), SIHM (short interval horizontal movements), and SHAKE (short stroked SIRV). The 36-minute period SIRV movements occurred at higher moisture levels. The 176-minute period SIHM occurred at lower moisture levels and ceased as the stress increased. The SHAKE movements were initiated with further stresses. The SLEEP (circadian, diurnal) movements ceased with further stress. The last to cease just prior to permanent wilting were the SHAKE movements. PMID:16659123

  1. BOREAS TE-12 Leaf Gas Exchange Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Arkebauer, Timothy J.; Yang, Litao

    2000-01-01

    The BOREAS TE-12 team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, and gas exchange of boreal vegetation. This data set contains measurements of leaf gas exchange conducted in the SSA during the growing seasons of 1994 and 1995 using a portable gas exchange system. The data are stored 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 Center (DAAC).

  2. Phoma glycinicola (Red Leaf Blotch): A threat to soybean production in the USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Red leaf blotch of soybean [Glycine max (L.) Merr.] is the common name for the disease caused by the fungal pathogen Phoma glycinicola Gruyter & Boerema. Other names for red leaf blotch inlcude Dactuliophora leaf spot, Pyrenochaeta leaf blotch, and Pyrenochaeta leaf spot. The disease was first repor...

  3. INTERSPECFIC VARIATION IN SO2 FLUX - LEAF SURFACE 'VERSUS' INTERNAL FLUX, AND COMPONENTS OF LEAF CONDUCTANCE

    EPA Science Inventory

    The object of the study was to clarify the relationships among stomatal, residual, and epidermal conductances in determining the flux of SO2 air pollution to leaves. Variations in leaf SO2 and H2O vapor fluxes were determined using four plant species: Pisum sativum L. (garden pea...

  4. CREB (cAMP response element binding protein) and C/EBPalpha (CCAAT/enhancer binding protein) are required for the superstimulation of phosphoenolpyruvate carboxykinase gene transcription by adenoviral E1a and cAMP.

    PubMed Central

    Routes, J M; Colton, L A; Ryan, S; Klemm, D J

    2000-01-01

    In the present study, we observed superstimulated levels of cAMP-stimulated transcription from the phosphoenolpyruvate carboxykinase (PEPCK) gene promoter in cells infected with wild-type adenovirus expressing 12 S and 13 S E1a proteins, or in cells expressing 13 S E1a alone. cAMP-stimulated transcription was inhibited in cells expressing only 12 S E1a, but slightly elevated in cells expressing E1a proteins with mutations in conserved regions 1 or 2, leading us to conclude that the superstimulation was mediated by conserved region 3 of 13 S E1a. E1a failed to enhance cAMP-stimulated transcription from promoters containing mutations that abolish binding by cAMP response element binding protein (CREB) or CCAAT/enhancer binding proteins (C/EBPs). This result was supported by experiments in which expression of dominant-negative CREB and/or C/EBP proteins repressed E1a- and cAMP-stimulated transcription from the PEPCK gene promoter. In reconstitution experiments using a Gal4-responsive promoter, E1a enhanced cAMP-stimulated transcription when chimaeric Gal4-CREB and Gal4-C/EBPalpha were co-expressed. Phosphorylation of CREB on serine-133 was stimulated in cells treated with dibutyryl cAMP, whereas phosphorylation of C/EBPalpha was increased by E1a expression. Our data support a model in which cAMP agonists increase CREB activity and stimulate PEPCK gene transcription, a process that is enhanced by E1a through the phosphorylation of C/EBPalpha. PMID:11085926

  5. Purification and characterization of high- and low-molecular-mass isoforms of phosphoenolpyruvate carboxylase from Chlamydomonas reinhardtii. Kinetic, structural and immunological evidence that the green algal enzyme is distinct from the prokaryotic and higher plant enzymes.

    PubMed Central

    Rivoal, J; Plaxton, W C; Turpin, D H

    1998-01-01

    Phosphoenolpyruvate carboxylase (PEPC) is a key enzyme in the supply of carbon skeletons for the assimilation of nitrogen by green algae. Two PEPC isoforms with respective native molecular masses of 400 (PEPC1) and 650 (PEPC2) kDa have been purified from Chlamydomonas reinhardtii CW-15 cc1883 (Chlorophyceae). SDS/PAGE, immunoblot and CNBr peptide-mapping analyses indicate the presence of the same 100 kDa PEPC catalytic subunit in both isoforms. PEPC1 is a homotetramer, whereas PEPC2 seems to be a complex between the PEPC catalytic subunit and other immunologically unrelated polypeptides of 50-70 kDa. Kinetic analyses indicate that these PEPC isoforms are (1) differentially regulated by pH, (2) activated by glutamine and dihydroxyacetone phosphate and (3) inhibited by glutamate, aspartate, 2-oxoglutarate and malate. These results are consistent with the current model for the regulation of anaplerotic carbon fixation in green algae, and demonstrate that green algal PEPCs are uniquely regulated by glutamine. Several techniques were used to assess the structural relationships between C. reinhardtii PEPC and the higher plant or prokaryotic enzyme. Immunoblot studies using anti-(green algal or higher plant PEPC) IgGs suggested that green algal (C. reinhardtii, Selenastrum minutum), higher plant (maize, banana fruit, tobacco) and prokaryotic (Synechococcus leopoliensis, Escherichia coli) PEPCs have little or no immunological relatedness. Moreover, the N-terminal amino acid sequence of the C. reinhardtii PEPC subunit did not have significant similarity to the highly conserved corresponding region in enzymes from higher plants, and CNBr cleavage patterns of green algal PEPCs were distinct from those of higher plant and cyanobacterial PEPCs. These results point to significant evolutionary divergence between green algal, higher plant and prokaryotic PEPCs. PMID:9512480

  6. Estimating leaf photosynthetic pigments information by stepwise multiple linear regression analysis and a leaf optical model

    NASA Astrophysics Data System (ADS)

    Liu, Pudong; Shi, Runhe; Wang, Hong; Bai, Kaixu; Gao, Wei

    2014-10-01

    Leaf pigments are key elements for plant photosynthesis and growth. Traditional manual sampling of these pigments is labor-intensive and costly, which also has the difficulty in capturing their temporal and spatial characteristics. The aim of this work is to estimate photosynthetic pigments at large scale by remote sensing. For this purpose, inverse model were proposed with the aid of stepwise multiple linear regression (SMLR) analysis. Furthermore, a leaf radiative transfer model (i.e. PROSPECT model) was employed to simulate the leaf reflectance where wavelength varies from 400 to 780 nm at 1 nm interval, and then these values were treated as the data from remote sensing observations. Meanwhile, simulated chlorophyll concentration (Cab), carotenoid concentration (Car) and their ratio (Cab/Car) were taken as target to build the regression model respectively. In this study, a total of 4000 samples were simulated via PROSPECT with different Cab, Car and leaf mesophyll structures as 70% of these samples were applied for training while the last 30% for model validation. Reflectance (r) and its mathematic transformations (1/r and log (1/r)) were all employed to build regression model respectively. Results showed fair agreements between pigments and simulated reflectance with all adjusted coefficients of determination (R2) larger than 0.8 as 6 wavebands were selected to build the SMLR model. The largest value of R2 for Cab, Car and Cab/Car are 0.8845, 0.876 and 0.8765, respectively. Meanwhile, mathematic transformations of reflectance showed little influence on regression accuracy. We concluded that it was feasible to estimate the chlorophyll and carotenoids and their ratio based on statistical model with leaf reflectance data.

  7. Autumnal leaf senescence in Miscanthus × giganteus and leaf [N] differ by stand age.

    PubMed

    Boersma, Nicholas N; Dohleman, Frank G; Miguez, Fernando E; Heaton, Emily A

    2015-07-01

    Poor first winter survival in Miscanthus × giganteus has been anecdotally attributed to incomplete first autumn senescence, but these assessments never paired first-year with older M. × giganteus in side-by-side trials to separate the effect of weather from stand age. Here CO2 assimilation rate (A), photosystem II efficiency (ΦPSII), and leaf N concentration ([N]) were used to directly compare senescence in first, second, and third-year stands of M. × giganteus. Three M. × giganteus fields were planted with eight plots, one field each in 2009, 2010, and 2011. To quantify autumnal leaf senescence of plants within each stand age, photosynthetic and leaf [N] measurements were made twice weekly from early September until a killing frost. Following chilling events (daily temperature averages below 10 °C), photosynthetic rates in first year plants rebounded to a greater degree than those in second- and third-year plants. By the end of the growing season, first-year M. × giganteus had A and ΦPSII rates up to 4 times greater than third-year M. × giganteus, while leaf [N] was up to 2.4 times greater. The increased photosynthetic capability and leaf N status in first-year M. × giganteus suggests that the photosynthetic apparatus was not dismantled before a killing frost, thus potentially limiting nutrient translocation, and may explain why young M. × giganteus stands do not survive winter when older stands do. Because previous senescence research has primarily focused on annual or woody species, our results suggest that M. × giganteus may be an interesting herbaceous perennial system to investigate the interactive effects of plant ageing and nutrient status on senescence and may highlight management strategies that could potentially increase winter survival rates in first-year stands. PMID:25873682

  8. Leaf thickness controls variation in leaf mass per area (LMA) among grazing-adapted grasses in Serengeti.

    PubMed

    Griffith, Daniel M; Quigley, Kathleen M; Anderson, T Michael

    2016-08-01

    Leaf mass per area (LMA) is a primary plant functional trait that represents the cost of constructing a leaf. Ultimately, plants modify LMA by altering leaf thickness (LT), leaf dry matter content (LDMC), or both. While LMA can be modified through both of these constituents, studies of LMA have found that there is variation in whether LT or LDMC changes are responsible for LMA-and the relationships change depending on the species or functional groups being compared. In this study, we used a phylogenetic framework to determine that evolutionary shifts in LMA are driven by LT, and not LDMC, among 45 Serengeti grass species. We considered two alternative hypotheses that could result in evolutionary correlation of LMA on LT but not LDMC: either (1) LT is more labile than LDMC-and is therefore a less costly means to change LMA or (2) LDMC is tightly coupled to a different dimension of leaf variation (e.g., leaf hydraulics), leaving LT as the source of variation in LMA. LT was not more labile than LDMC, leading us to conclude that the evolution of LMA has been shaped by LT because LDMC is responding to other demands on leaf physiology. We speculate that leaf hydraulics provide this constraint on LDMC. The decoupling of LDMC from LT may allow plants to better optimize resource allocation in ecosystems where gradients in light competition, herbivory, and aridity place competing demands on leaf economics. PMID:27098527

  9. The shape of a long leaf

    PubMed Central

    Liang, Haiyi; Mahadevan, L.

    2009-01-01

    Long leaves in terrestrial plants and their submarine counterparts, algal blades, have a typical, saddle-like midsurface and rippled edges. To understand the origin of these morphologies, we dissect leaves and differentially stretch foam ribbons to show that these shapes arise from a simple cause, the elastic relaxation via bending that follows either differential growth (in leaves) or differential stretching past the yield point (in ribbons). We quantify these different modalities in terms of a mathematical model for the shape of an initially flat elastic sheet with lateral gradients in longitudinal growth. By using a combination of scaling concepts, stability analysis, and numerical simulations, we map out the shape space for these growing ribbons and find that as the relative growth strain is increased, a long flat lamina deforms to a saddle shape and/or develops undulations that may lead to strongly localized ripples as the growth strain is localized to the edge of the leaf. Our theory delineates the geometric and growth control parameters that determine the shape space of finite laminae and thus allows for a comparative study of elongated leaf morphology. PMID:19966215

  10. Proteomic profiling of Tectona grandis L. leaf.

    PubMed

    Quiala, Elisa; Cañal, María Jesús; Rodríguez, Roberto; Yagüe, Norma; Chávez, Maité; Barbón, Raúl; Valledor, Luis

    2012-04-01

    Tectona grandis L. (teak) is one of the premier hardwood timbers in the world, ranking at present in the top five tropical hardwood species in terms of worldwide plantation area. Characterization of the proteins present in teak leaves will provide a basis for the development of new tools aimed at assisting tree selection, the monitoring of plant propagation, and the certification of clonal and phenotypic identities. In this paper, we describe the extraction, separation, and identification of leaf proteins from T. grandis using a TCA/acetone protocol, 2DE, and MALDI-TOF. After TCA/acetone protein extraction of leaves, 998 well-resolved spots were detected in Coomassie-stained gels within the 10-114 kDa relative molecular mass (Mr) range at a pH ranging from 3 to 11. A total of 120 spots were digested and subjected to MS. Of these, 100 nonredundant protein species were successfully identified. Functional classification of the identified proteins revealed that proteins involved in photosynthesis, protein translation, and energy production were the most abundant. This work is the first high-throughput attempt to study the T. grandis leaf proteome and represents a stepping stone for further differential expression proteomic studies related to growth, development, biomass production, and culture-associated physiological responses. PMID:22522810

  11. A quest for the artificial leaf.

    PubMed

    Janna Olmos, Julian David; Kargul, Joanna

    2015-09-01

    It has been estimated that the energy captured in one hour of sunlight that reaches our planet is equivalent to annual energy production by human population globally. To efficiently capture the practically inexhaustible solar energy and convert it into high energy density solar fuels provides an attractive 'green' alternative to running our present day economies on rapidly depleting fossil fuels, especially in the context of ever growing global energy demand. Natural photosynthesis represents one of the most fundamental processes that sustain life on Earth. It provides nearly all the oxygen we breathe, the food we consume and fossil fuels that we so much depend on. Imitating the reactions that occur at the early stages of photosynthesis represents the main challenge in the quest for construction of an efficient, robust, self-renewing and cost-effective 'artificial leaf'. In this review we summarize the main molecular features of the natural solar energy converters, photosystem I and photosystem II, that allow them to operate at high quantum efficiencies, and thus inspire the smart matrix design of the artificial solar-to-fuel devices. We also discuss the main challenges that face the field and overview selected recent technological advances that have tremendously accelerated the race for a fully operational artificial leaf that could serve as a viable alternative to fossil fuels for energy production. PMID:26183656

  12. Pharmacognostical evaluation of Barringtonia acutangula leaf.

    PubMed

    Padmavathi, Dharamaraj; Susheela, Lakshmi; Bharathi, Rajkishore Vijaya

    2011-01-01

    Barringtonia acutangula (L.) Gaertn. (Family: Lecythidaceae) is an evergreen tree with simple, alternate leaves, long pendulous racemes, dark scarlet flowers, and ellipsoid to ovoid berries containing one ovoid black seed. The present study deals with a detailed pharmacognostical study on the leaf of the crude drug, B. acutangula. Morphoanatomy of the leaf was studied using light and confocal microscopy and World Health Organization (WHO) guidelines on quality control methods for medicinal plant materials. Literature reveals that the phytoconstituents like tanginol, barrinic acid, and barringenic acid are present in the wood and fruits of this plant. Our preliminary phytochemical studies of the powdered leaves revealed the presence of terpenes, flavanoids, carbohydrates, tannins, steroids, and glycosides. The physico-chemical, morphological, histological parameters, and High Performance-Thin Layer Chromatographic (HPTLC) profile presented in this paper may be proposed as parameters to establish the authenticity of B. acutangula and can possibly help to differentiate the drug from its other species and the pharmacognostic profile of the leaves presented here will assist in standardization viz., quality, purity, and sample identification. PMID:21897641

  13. Pharmacognostical evaluation of Barringtonia acutangula leaf

    PubMed Central

    Padmavathi, Dharamaraj; Susheela, Lakshmi; Bharathi, Rajkishore Vijaya

    2011-01-01

    Barringtonia acutangula (L.) Gaertn. (Family: Lecythidaceae) is an evergreen tree with simple, alternate leaves, long pendulous racemes, dark scarlet flowers, and ellipsoid to ovoid berries containing one ovoid black seed. The present study deals with a detailed pharmacognostical study on the leaf of the crude drug, B. acutangula. Morphoanatomy of the leaf was studied using light and confocal microscopy and World Health Organization (WHO) guidelines on quality control methods for medicinal plant materials. Literature reveals that the phytoconstituents like tanginol, barrinic acid, and barringenic acid are present in the wood and fruits of this plant. Our preliminary phytochemical studies of the powdered leaves revealed the presence of terpenes, flavanoids, carbohydrates, tannins, steroids, and glycosides. The physico-chemical, morphological, histological parameters, and High Performance-Thin Layer Chromatographic (HPTLC) profile presented in this paper may be proposed as parameters to establish the authenticity of B. acutangula and can possibly help to differentiate the drug from its other species and the pharmacognostic profile of the leaves presented here will assist in standardization viz., quality, purity, and sample identification. PMID:21897641

  14. Protein changes during oat leaf senescence

    SciTech Connect

    Dhindsa, R.S.; Tsai, C.D.; Lalonde, L.

    1986-04-01

    Protein changes during in situ and in vitro senescence of the first leaf of 8-day old seedlings of Avena sativa cv. Victory have been examined. Senescence was induced by placing either intact seedlings or by floating the apical 3 cm-long leaf segments on water, in dark at 27 C for 0 to 4 days. Total protein content and chlorophyll content declined steadily during senescence. Rate of amino acid uptake, studied with /sup 14/C-B-alanine, declined sharply. Rate of protein synthesis decreased during the first 24 h during in vitro, and 48 h during in situ senescence. Thereafter, the rate increased sharply. At the end of 4 days the rate of protein synthesis had again declined in case of in vitro senescence but remained high in case of in situ senescence. Large changes in protein patterns, as shown by 1-D and 2-D PAGE, also occurred during senescence. Major changes in the population of translatable mRNAs that occur during in situ and in vitro senescence will be compared and discussed.

  15. Induction of Barley Leaf Urease 1

    PubMed Central

    Chen, Yuguang; Ching, Te May

    1988-01-01

    Foliar urea application on barley plants increased leaf urease activity for 5 hours with a peak of 20-fold at 2 hours. To discern the mode of urease induction, urea with or without inhibitors and [35S]methionine were incubated with leaf sections for different lengths of time. Urease was extracted, partially purified, electrophoresed, and then quantified by fluorogram. Five urease (U) isozymes were separated by PAGE. Ua and Ub might be polymers or complexes that occurred only at the peak of induced activity. U1 and U2 appeared at 0.5 and 0.75 hour, respectively, after urea induction, peaked at 2 hours, and persisted only in treated leaves for several additional hours indicating that they are transient inducible forms. U3 was the constitutive form present in control and treated leaves. Induction with cordycepin or cycloheximide completely prevented urea stimulated activity and nullified the existence of isozymes Ua, Ub, U1, and U2. 35S-U1, which was labeled in the last hour of induction, appeared on fluorogram 1 hour after induction, peaked at 2 hours, and declined at 3 hours. Results indicated that de novo synthesis of urease is activated by the influx of urea. Images Fig. 2 Fig. 4 PMID:16666013

  16. 9 CFR 319.702 - Lard, leaf lard.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... CERTIFICATION DEFINITIONS AND STANDARDS OF IDENTITY OR COMPOSITION Fats, Oils, Shortenings § 319.702 Lard, leaf lard. (a) Lard is the fat rendered from clean and sound edible tissues from swine. The tissues may be... leaf (abdominal) fat. (b) Lard (when properly labeled) may be hardened by the use of lard stearin...

  17. 9 CFR 319.702 - Lard, leaf lard.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CERTIFICATION DEFINITIONS AND STANDARDS OF IDENTITY OR COMPOSITION Fats, Oils, Shortenings § 319.702 Lard, leaf lard. (a) Lard is the fat rendered from clean and sound edible tissues from swine. The tissues may be... leaf (abdominal) fat. (b) Lard (when properly labeled) may be hardened by the use of lard stearin...

  18. 9 CFR 319.702 - Lard, leaf lard.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CERTIFICATION DEFINITIONS AND STANDARDS OF IDENTITY OR COMPOSITION Fats, Oils, Shortenings § 319.702 Lard, leaf lard. (a) Lard is the fat rendered from clean and sound edible tissues from swine. The tissues may be... leaf (abdominal) fat. (b) Lard (when properly labeled) may be hardened by the use of lard stearin...

  19. 9 CFR 319.702 - Lard, leaf lard.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CERTIFICATION DEFINITIONS AND STANDARDS OF IDENTITY OR COMPOSITION Fats, Oils, Shortenings § 319.702 Lard, leaf lard. (a) Lard is the fat rendered from clean and sound edible tissues from swine. The tissues may be... leaf (abdominal) fat. (b) Lard (when properly labeled) may be hardened by the use of lard stearin...

  20. 9 CFR 319.702 - Lard, leaf lard.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... CERTIFICATION DEFINITIONS AND STANDARDS OF IDENTITY OR COMPOSITION Fats, Oils, Shortenings § 319.702 Lard, leaf lard. (a) Lard is the fat rendered from clean and sound edible tissues from swine. The tissues may be... leaf (abdominal) fat. (b) Lard (when properly labeled) may be hardened by the use of lard stearin...

  1. Genetics and breeding of bacterial leaf spot resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) is a globally important disease of whole head and baby leaf lettuce that reduces crop yield and quality. Host resistance is the most feasible method to reduce disease losses. Screening Lactuca accessions has id...

  2. Immunomodulatory effect of dietary Safflower leaf on coccidiosis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to evaluate the dietary effect of safflower leaf on protective immunity against coccidiosis, the most economically important parasitic disease in poultry. White Leghorn chicks were fed a standard diet without or with safflower leaf, the animals were uninfected or orally infe...

  3. 7 CFR 29.3153 - Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., smooth, clear finish, deep color intensity, spready, 20″ or over in length, 95 percent uniform, and 5.... B1FR Choice Tannish-red Leaf. Fleshy to medium body, ripe, open, smooth, clear finish, deep color... percent injury tolerance. B5R Low red Leaf. Heavy to fleshy, mature, close, rough, dingy finish,...

  4. 7 CFR 29.3153 - Leaf (B Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., smooth, clear finish, deep color intensity, spready, 20″ or over in length, 95 percent uniform, and 5.... B1FR Choice Tannish-red Leaf. Fleshy to medium body, ripe, open, smooth, clear finish, deep color... percent injury tolerance. B5R Low red Leaf. Heavy to fleshy, mature, close, rough, dingy finish,...

  5. 7 CFR 29.3153 - Leaf (B Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., smooth, clear finish, deep color intensity, spready, 20″ or over in length, 95 percent uniform, and 5.... B1FR Choice Tannish-red Leaf. Fleshy to medium body, ripe, open, smooth, clear finish, deep color... percent injury tolerance. B5R Low red Leaf. Heavy to fleshy, mature, close, rough, dingy finish,...

  6. 7 CFR 29.3153 - Leaf (B Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., smooth, clear finish, deep color intensity, spready, 20″ or over in length, 95 percent uniform, and 5.... B1FR Choice Tannish-red Leaf. Fleshy to medium body, ripe, open, smooth, clear finish, deep color... percent injury tolerance. B5R Low red Leaf. Heavy to fleshy, mature, close, rough, dingy finish,...

  7. 7 CFR 29.2662 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... percent injury tolerance. B4F Fair Medium-brown Heavy Leaf. Medium body, mature, close, lean in oil... tolerance. B5F Low Medium-brown Heavy Leaf. Medium body, mature, close, lean in oil, inelastic, weak, dull... to heavy body, mature, close, lean in oil, inelastic, weak, dull finish, pale color intensity,...

  8. The Analysis of Leaf Shape Using Fractal Geometry.

    ERIC Educational Resources Information Center

    Hartvigsen, Gregg

    2000-01-01

    Describes ways to examine leaf structure and shape using fractal geometry. Students can test hypotheses using the leaves of replicated plants to look for non-linear trends in leaf shape along the stems of plants, across species, and under different environmental growth conditions. (SAH)

  9. Coconut leaf bioactivity toward generalist maize insect pests

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tropical plants are often more resistant to insects than temperate plants due to evolution of robust defenses to cope with a more constant insect threat. Coconut (Cocos nucifera L.) has very few chewing leaf feeding insect pests and was tested against two omnivorous leaf feeding caterpillar species,...

  10. Cucurbit leaf crumple virus Identified in Common Bean in Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Detection of Cucurbit leaf crumple virus in green beans in Florida suggests that this virus may be more widely distributed than previously known in the state and that green bean (and potentially other legumes) are potential reservoirs for Cucurbit leaf crumple virus....

  11. New strategies for managing leaf diseases of alfalfa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf diseases are a serious problem for alfalfa management in all areas where alfalfa is grown. Defoliation from leaf diseases has been measured from 3-71% depending on time of year, environmental conditions, age of the stand, and location. In addition to yield loss, foliar diseases can reduce forag...

  12. 7 CFR 29.1163 - Smoking Leaf (H Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Smoking Leaf (H Group). 29.1163 Section 29.1163... REGULATIONS TOBACCO INSPECTION Standards Grades § 29.1163 Smoking Leaf (H Group). This group consists of leaves normally grown at or above the midportion of the stalk. Leaves of the H group show a high...

  13. Oregon 'Pinot noir' grape anthocyanin enhancement by early leaf removal

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Complete cluster zone leaf removal of ‘Pinot noir’ was initiated at three separate pre-véraison growth stages (bloom, grain-pea size, and bunch closure) and maintained leaf free until harvest for four growing seasons (2008-2011). Fruit anthocyanin composition was examined at harvest for the last tw...

  14. Molecular Mapping of Wheat Leaf Rust Resistance Gene Lr42

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf rust, caused by Puccinia triticina Eriks., is an important foliar disease of wheat (Triticum aestivum L.) worldwide. Leaf rust resistance gene Lr42 from Aegilops tauschii Coss. has been used as a source of rust resistance in breeding programs. To identify molecular markers closely linked to Lr4...

  15. Hands-On Whole Science: A Leaf Sampler.

    ERIC Educational Resources Information Center

    Kepler, Lynne

    1991-01-01

    Presents two elementary school activities to help students learn about autumn. The activities use autumn leaves to teach that each type of tree has its own distinctive type of leaf. One activity involves tracing, drawing, and writing about leaves; the other involves making a quilt using leaf designs. (SM)

  16. Elucidating the role of transport processes in leaf glucosinolate distribution.

    PubMed

    Madsen, Svend Roesen; Olsen, Carl Erik; Nour-Eldin, Hussam Hassan; Halkier, Barbara Ann

    2014-11-01

    In Arabidopsis (Arabidopsis thaliana), a strategy to defend its leaves against herbivores is to accumulate glucosinolates along the midrib and at the margin. Although it is generally assumed that glucosinolates are synthesized along the vasculature in an Arabidopsis leaf, thereby suggesting that the margin accumulation is established through transport, little is known about these transport processes. Here, we show through leaf apoplastic fluid analysis and glucosinolate feeding experiments that two glucosinolate transporters, GTR1 and GTR2, essential for long-distance transport of glucosinolates in Arabidopsis, also play key roles in glucosinolate allocation within a mature leaf by effectively importing apoplastically localized glucosinolates into appropriate cells. Detection of glucosinolates in root xylem sap unambiguously shows that this transport route is involved in root-to-shoot glucosinolate allocation. Detailed leaf dissections show that in the absence of GTR1 and GTR2 transport activity, glucosinolates accumulate predominantly in leaf margins and leaf tips. Furthermore, we show that glucosinolates accumulate in the leaf abaxial epidermis in a GTR-independent manner. Based on our results, we propose a model for how glucosinolates accumulate in the leaf margin and epidermis, which includes symplasmic movement through plasmodesmata, coupled with the activity of putative vacuolar glucosinolate importers in these peripheral cell layers. PMID:25209984

  17. 7 CFR 29.2662 - Heavy Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... percent injury tolerance. B4F Fair Medium-brown Heavy Leaf. Medium body, mature, close, lean in oil... tolerance. B5F Low Medium-brown Heavy Leaf. Medium body, mature, close, lean in oil, inelastic, weak,...

  18. 7 CFR 29.2438 - Thin Leaf (C Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... Fair Light-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak... Light-brown Thin Leaf. Thin to medium body, mature to ripe, close, lean in oil, inelastic, weak,...

  19. 7 CFR 29.2663 - Thin Leaf (C Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... tolerance. C4L Fair Light-brown Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull finish... Thin Leaf. Thin, mature, close, lean in oil, inelastic, weak, dull finish, pale color intensity,...

  20. Timing and duration of autumn leaf development in Sweden

    NASA Astrophysics Data System (ADS)

    Bolmgren, Kjell

    2014-05-01

    The growing season is changing in both ends and autumn phases seem to be responding in more diverse ways than spring events. Indeed, we know little about autumn leaf phenological strategies and how they are correlated with fitness components or ecosystem properties, and how they vary between species and over bioclimatic gradients. In this study more than 10 000 students were involved in observing autumn leaf development at 378 sites all over Sweden (55-68°N). They followed an image based observation protocol classifying autumn leaf development into five levels, from summer green (level 0) to 100% autumn leaf colored (level 4) canopy. In total, they submitted almost 12 000 observations between August 9 and November 15. 75% of the observations were made on the common species of Populus tremula, Betula pendula/pubescens and Sorbus aucuparia. The expected (negative) correlation between latitude and start of leaf senescence (level 2) was found in Populus and Betula, but not in Sorbus. The duration of the leaf senescence period, defined as the period between 1/3 (level 2) and 100% (level 4) of the canopy autumn leaf colored, was negatively correlated with latitude in Populus and Betula, but not in Sorbus. There was also a strong (negative) correlation of the start (level 2) and the duration of the leaf senescence in the early senescing Sorbus and Betula, while this effect was weaker in the late senescing Populus.

  1. 41. VIEW OF WEST BASCULE LEAF LOCKING PINS IN EXTENDED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. VIEW OF WEST BASCULE LEAF LOCKING PINS IN EXTENDED POSITION - PINS FIT INTO MATCHING BUSHINGS ON THE EAST LEAF AND SECURE THE EAST AND WEST SECTIONS WHEN THE BRIDGE IS DOWN. - Tomlinson Bridge, Spanning Quinnipiac River at Forbes Street (U.S. Route 1), New Haven, New Haven County, CT

  2. Pulvinus activity, leaf movement and leaf water-use efficiency of bush bean ( Phaseplus vulgaris L.) in a hot environment

    NASA Astrophysics Data System (ADS)

    Raeini-Sarjaz, Mahmoud; Chalavi, Vida

    2008-11-01

    Pulvinus activity of Phaseolus species in response to environmental stimuli plays an essential role in heliotropic leaf movement. The aims of this study were to monitor the continuous daily pulvinus movement and pulvinus temperature, and to evaluate the effects of leaf movements, on a hot day, on instantaneous leaf water-use efficiency (WUEi), leaf gas exchange, and leaf temperature. Potted plants of Phaseolus vulgaris L. var. Provider were grown in Chicot sandy loam soil under well-watered conditions in a greenhouse. When the second trifoliate leaf was completely extended, one plant was selected to measure pulvinus movement using a beta-ray gauging (BRG) meter with a point source of thallium-204 (204Tl). Leaf gas exchange measurements took place on similar leaflets of three plants at an air temperature interval of 33-42°C by a steady-state LI-6200 photosynthesis system. A copper-constantan thermocouple was used to monitor pulvinus temperature. Pulvinus bending followed the daily diurnal rhythm. Significant correlations were found between the leaf-incident angle and the stomatal conductance ( R 2 = 0.54; P < 0.01), and photosynthesis rate ( R 2 = 0.84; P < 0.01). With a reduction in leaf-incidence angle and increase in air temperature, WUEi was reduced. During the measurements, leaf temperature remained below air temperature and was a significant function of air temperature ( r = 0.92; P < 0.01). In conclusion, pulvinus bending followed both light intensity and air temperature and influenced leaf gas exchange.

  3. Effects of nitrogen application rate and leaf age on the distribution pattern of leaf SPAD readings in the rice canopy.

    PubMed

    Yang, Hu; Li, Jinwen; Yang, Jingping; Wang, Hua; Zou, Junliang; He, Junjun

    2014-01-01

    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(-1)The 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. PMID:24520386

  4. Effects of Nitrogen Application Rate and Leaf Age on the Distribution Pattern of Leaf SPAD Readings in the Rice Canopy

    PubMed Central

    Yang, Jingping; Wang, Hua; Zou, Junliang; He, Junjun

    2014-01-01

    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. PMID:24520386

  5. Ocimum sanctum leaf extract induces drought stress tolerance in rice.

    PubMed

    Pandey, Veena; Ansari, M W; Tula, Suresh; Sahoo, R K; Bains, Gurdeep; Kumar, J; Tuteja, Narendra; Shukla, Alok

    2016-05-01

    Ocimum leaves are highly enriched in antioxidant components. Thus, its leaf extract, if applied in plants, is believed to efficiently scavenge ROS, thereby preventing oxidative damage under drought stress. Thus, the present study was performed in kharif 2013 and rabi 2014 season to evaluate the effect of aqueous leaf extract of Ocimum sanctum against drought stress in 2 rice genotype under glass house conditions. Here we show that various morpho- physiological (chlorophyll fluorescence, leaf rolling score, leaf tip burn, number of senesced leaves and total dry matter) and biochemical parameters (proline, malondialdehyde and superoxide dismutase content) were amended by Ocimum treatment in both the seasons. Application of Ocimum extract increased expression of dehydrin genes, while reducing expression of aquaporin genes in drought stressed rice plant. Thus, application of Ocimum leaf extract under drought stress can be suggested as a promising strategy to mitigate drought stress in economical, accessible and ecofriendly manner. PMID:26890603

  6. Functional overlap of the Arabidopsis leaf and root microbiota.

    PubMed

    Bai, Yang; Müller, Daniel B; Srinivas, Girish; Garrido-Oter, Ruben; Potthoff, Eva; Rott, Matthias; Dombrowski, Nina; Münch, Philipp C; Spaepen, Stijn; Remus-Emsermann, Mitja; Hüttel, Bruno; McHardy, Alice C; Vorholt, Julia A; Schulze-Lefert, Paul

    2015-12-17

    Roots and leaves of healthy plants host taxonomically structured bacterial assemblies, and members of these communities contribute to plant growth and health. We established Arabidopsis leaf- and root-derived microbiota culture collections representing the majority of bacterial species that are reproducibly detectable by culture-independent community sequencing. We found an extensive taxonomic overlap between the leaf and root microbiota. Genome drafts of 400 isolates revealed a large overlap of genome-encoded functional capabilities between leaf- and root-derived bacteria with few significant differences at the level of individual functional categories. Using defined bacterial communities and a gnotobiotic Arabidopsis plant system we show that the isolates form assemblies resembling natural microbiota on their cognate host organs, but are also capable of ectopic leaf or root colonization. While this raises the possibility of reciprocal relocation between root and leaf microbiota members, genome information and recolonization experiments also provide evidence for microbiota specialization to their respective niche. PMID:26633631

  7. Autumn leaf subsidies influence spring dynamics of freshwater plankton communities.

    PubMed

    Fey, Samuel B; Mertens, Andrew N; Cottingham, Kathryn L

    2015-07-01

    While ecologists primarily focus on the immediate impact of ecological subsidies, understanding the importance of ecological subsidies requires quantifying the long-term temporal dynamics of subsidies on recipient ecosystems. Deciduous leaf litter transferred from terrestrial to aquatic ecosystems exerts both immediate and lasting effects on stream food webs. Recently, deciduous leaf additions have also been shown to be important subsidies for planktonic food webs in ponds during autumn; however, the inter-seasonal effects of autumn leaf subsidies on planktonic food webs have not been studied. We hypothesized that autumn leaf drop will affect the spring dynamics of freshwater pond food webs by altering the availability of resources, water transparency, and the metabolic state of ponds. We created leaf-added and no-leaf-added field mesocosms in autumn 2012, allowed mesocosms to ice-over for the winter, and began sampling the physical, chemical, and biological properties of mesocosms immediately following ice-off in spring 2013. At ice-off, leaf additions reduced dissolved oxygen, elevated total phosphorus concentrations and dissolved materials, and did not alter temperature or total nitrogen. These initial abiotic effects contributed to higher bacterial densities and lower chlorophyll concentrations, but by the end of spring, the abiotic environment, chlorophyll and bacterial densities converged. By contrast, zooplankton densities diverged between treatments during the spring, with leaf additions stimulating copepods but inhibiting cladocerans. We hypothesized that these differences between zooplankton orders resulted from resource shifts following leaf additions. These results suggest that leaf subsidies can alter both the short- and long-term dynamics of planktonic food webs, and highlight the importance of fully understanding how ecological subsidies are integrated into recipient food webs. PMID:25761444

  8. Spatial and temporal variations in leaf area index, specific leaf area and leaf nitrogen of two co-occurring savanna tree species.

    PubMed

    Simioni, Guillaume; Gignoux, Jacques; Le Roux, Xavier; Appé, Raphaëlle; Benest, Daniele

    2004-02-01

    Foliage growth, mass- and area-based leaf nitrogen concentrations (Nm and N a) and specific leaf area (SLA) were surveyed during a complete vegetation cycle for two co-occurring savanna tree species: Crossopteryx febrifuga (Afzel. ex G. Don) Benth. and Cussonia arborea A. Rich. The study was conducted in the natural reserve of Lamto, Ivory Coast, on isolated and clumped trees. Leaf flush occurred before the beginning of the rainy season. Maximum leaf area index (LAI), computed on a projected canopy basis for individual trees, was similar (mean of about 4) for both species. Seasonal courses of the ratio of actual to maximum LAI were similar for individuals of the same species, but differed between species. For C. febrifuga, clumped trees reached their maximum LAI before isolated trees. The LAI of C. arborea trees did not differ between clumped and isolated individuals, but maximum LAI was reached about 2 months later than for C. febrifuga. Leaf fall was associated with decreasing soil water content for C. arborea. For C. febrifuga, leaf fall started before the end of the rainy period and was independent of changes in soil water content. These features lead to a partial niche separation in time for light resource acquisition between the two species. Although Nm, N a and SLA decreased with time, SLA and N a decreased later in the vegetation cycle for C. arborea than for C. febrifuga. For both species, N a decreased and SLA increased with decreasing leaf irradiance within the canopy, although effects of light on leaf characteristics did not differ between isolated and clumped trees. Given relationships between N a and photosynthetic capacities previously reported for these species, our results show that C. arborea exhibits higher photosynthetic capacity than C. febrifuga during most of the vegetation cycle and at all irradiances. PMID:14676036

  9. Leaf Lateral Asymmetry in Morphological and Physiological Traits of Rice Plant

    PubMed Central

    Yuan, Shen; Li, Yong; Peng, Shaobing

    2015-01-01

    Leaf lateral asymmetry in width and thickness has been reported previously in rice. However, the differences between the wide and narrow sides of leaf blade in other leaf morphological and physiological traits were not known. This study was conducted to quantify leaf lateral asymmetry in leaf width, leaf thickness, specific leaf weight (SLW), leaf nitrogen (N) concentration based on dry weight (Nw) and leaf area (Na), and chlorophyll meter reading (SPAD). Leaf morphological and physiological traits of the two lateral halves of the top three leaves at heading stage were measured on 23 rice varieties grown in three growing seasons in two locations. Leaf lateral asymmetry was observed in leaf width, leaf thickness, Nw, Na, and SPAD, but not in SLW. On average, the leaf width of the wide side was about 17% higher than that of the narrow side. The wide side had higher leaf thickness than the narrow side whereas the narrow side had higher Nw, Na, and SPAD than the wide side. We conclude that the narrow side of leaf blade maintained higher leaf N status than the wide side based on all N-related parameters, which implies a possibility of leaf lateral asymmetry in photosynthetic rate in rice plant. PMID:26053267

  10. Leaf Lateral Asymmetry in Morphological and Physiological Traits of Rice Plant.

    PubMed

    Yuan, Shen; Li, Yong; Peng, Shaobing

    2015-01-01

    Leaf lateral asymmetry in width and thickness has been reported previously in rice. However, the differences between the wide and narrow sides of leaf blade in other leaf morphological and physiological traits were not known. This study was conducted to quantify leaf lateral asymmetry in leaf width, leaf thickness, specific leaf weight (SLW), leaf nitrogen (N) concentration based on dry weight (Nw) and leaf area (Na), and chlorophyll meter reading (SPAD). Leaf morphological and physiological traits of the two lateral halves of the top three leaves at heading stage were measured on 23 rice varieties grown in three growing seasons in two locations. Leaf lateral asymmetry was observed in leaf width, leaf thickness, Nw, Na, and SPAD, but not in SLW. On average, the leaf width of the wide side was about 17% higher than that of the narrow side. The wide side had higher leaf thickness than the narrow side whereas the narrow side had higher Nw, Na, and SPAD than the wide side. We conclude that the narrow side of leaf blade maintained higher leaf N status than the wide side based on all N-related parameters, which implies a possibility of leaf lateral asymmetry in photosynthetic rate in rice plant. PMID:26053267

  11. Leaf light reflectance, transmittance, absorptance, and optical and geometrical parameters for eleven plant genera with different leaf mesophyll arrangements.

    NASA Technical Reports Server (NTRS)

    Gausman, H. W.; Allen, W. A.; Wiegand, C. L.; Escobar, D. E.; Rodriguez, R. R.

    1971-01-01

    Review of research on radiation interactions within plant canopies and communities and interactions of various leaf structures (mesophyll arrangements) with electromagnetic radiation involved in the interpretation of data sensed from air or spacecraft. The hypothesis underlying the research reported is that leaf mesophyll arrangements influence spectral energy measurements of leaves.

  12. Detecting sugarcane yellow leaf virus in asymptomatic sugarcane leaves with hyperspectral remote sensing and associated leaf pigment changes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sugarcane yellow leaf caused by Sugarcane yellow leaf virus (SCYLV) does not produce visual symptoms in most susceptible sugarcane plants until late in the growing season. High-resolution, hyperspectral reflectance data from SCYLV-infected and non-infected leaves of two cultivars, LCP 85-384 and Ho...

  13. Infectivity of Euphorbia leaf curl virus and interaction with Tomato yellow leaf curl China betasatellite.

    PubMed

    Wu, Jianbing; Zulfiqar, Awais; Huang, Changjun

    2011-03-01

    To investigate the infectivity of Euphorbia leaf curl virus (EuLCV), an infectious clone was constructed and tested by agroinoculation and whitefly inoculation. EuLCV infected Nicotiana benthamiana, N. glutinosa, Solanum lycopersicum, Petunia hybrida efficiently upon agroinoculation and induced leaf curling, vein swelling and stunting in these plants but no symptoms in N. tabacum. Co-inoculation of EuLCV with a betasatellite DNA from an unrelated begomovirus enhanced symptoms in N. benthamiana, N. glutinosa, N. tabacum, S. lycopersicum and P. hybrida plants but had no effect on the accumulation of EuLCV DNA. Euphorbia pulcherrima plants were only infectable by insect transmission from agro-infected P. hybrida as a source. This is the first report about a monopartite begomovirus that has been reintroduced into a plant of the genus Euphorbia. PMID:21136128

  14. Evolution of Reproductive Morphology in Leaf Endophytes

    PubMed Central

    Wang, Zheng; Johnston, Peter R.; Yang, Zhu L.; Townsend, Jeffrey P.

    2009-01-01

    The endophytic lifestyle has played an important role in the evolution of the morphology of reproductive structures (body) in one of the most problematic groups in fungal classification, the Leotiomycetes (Ascomycota). Mapping fungal morphologies to two groups in the Leiotiomycetes, the Rhytismatales and Hemiphacidiaceae reveals significant divergence in body size, shape and complexity. Mapping ecological roles to these taxa reveals that the groups include endophytic fungi living on leaves and saprobic fungi living on duff or dead wood. Finally, mapping of the morphologies to ecological roles reveals that leaf endophytes produce small, highly reduced fruiting bodies covered with fungal tissue or dead host tissue, while saprobic species produce large and intricate fruiting bodies. Intriguingly, resemblance between asexual conidiomata and sexual ascomata in some leotiomycetes implicates some common developmental pathways for sexual and asexual development in these fungi. PMID:19158947

  15. Modelling transcriptional networks in leaf senescence.

    PubMed

    Penfold, Christopher A; Buchanan-Wollaston, Vicky

    2014-07-01

    The process of leaf senescence is induced by an extensive range of developmental and environmental signals and controlled by multiple, cross-linking pathways, many of which overlap with plant stress-response signals. Elucidation of this complex regulation requires a step beyond a traditional one-gene-at-a-time analysis. Application of a more global analysis using statistical and mathematical tools of systems biology is an approach that is being applied to address this problem. A variety of modelling methods applicable to the analysis of current and future senescence data are reviewed and discussed using some senescence-specific examples. Network modelling with a senescence transcriptome time course followed by testing predictions with gene-expression data illustrates the application of systems biology tools. PMID:24600015

  16. Functional relationships between leaf hydraulics and leaf economic traits in response to nutrient addition in subtropical tree species.

    PubMed

    Villagra, Mariana; Campanello, Paula I; Bucci, Sandra J; Goldstein, Guillermo

    2013-12-01

    Leaves can be both a hydraulic bottleneck and a safety valve against hydraulic catastrophic dysfunctions, and thus changes in traits related to water movement in leaves and associated costs may be critical for the success of plant growth. A 4-year fertilization experiment with nitrogen (N) and phosphorus (P) addition was done in a semideciduous Atlantic forest in northeastern Argentina. Saplings of five dominant canopy species were grown in similar gaps inside the forests (five control and five N + P addition plots). Leaf lifespan (LL), leaf mass per unit area (LMA), leaf and stem vulnerability to cavitation, leaf hydraulic conductance (K(leaf_area) and K(leaf_mass)) and leaf turgor loss point (TLP) were measured in the five species and in both treatments. Leaf lifespan tended to decrease with the addition of fertilizers, and LMA was significantly higher in plants with nutrient addition compared with individuals in control plots. The vulnerability to cavitation of leaves (P50(leaf)) either increased or decreased with the nutrient treatment depending on the species, but the average P50(leaf) did not change with nutrient addition. The P50(leaf) decreased linearly with increasing LMA and LL across species and treatments. These trade-offs have an important functional significance because more expensive (higher LMA) and less vulnerable leaves (lower P50(leaf)) are retained for a longer period of time. Osmotic potentials at TLP and at full turgor became more negative with decreasing P50(leaf) regardless of nutrient treatment. The K(leaf) on a mass basis was negatively correlated with LMA and LL, indicating that there is a carbon cost associated with increased water transport that is compensated by a longer LL. The vulnerability to cavitation of stems and leaves were similar, particularly in fertilized plants. Leaves in the species studied may not function as safety valves at low water potentials to protect the hydraulic pathway from water stress-induced cavitation

  17. Leaf morphophysiology of a Neotropical mistletoe is shaped by seasonal patterns of host leaf phenology.

    PubMed

    Scalon, Marina Corrêa; Rossatto, Davi Rodrigo; Domingos, Fabricius Maia Chaves Bicalho; Franco, Augusto Cesar

    2016-04-01

    Several mistletoe species are able to grow and reproduce on both deciduous and evergreen hosts, suggesting a degree of plasticity in their ability to cope with differences in intrinsic host functions. The aim of this study was to investigate the influence of host phenology on mistletoe water relations and leaf gas exchange. Mistletoe Passovia ovata parasitizing evergreen (Miconia albicans) hosts and P. ovata parasitizing deciduous (Byrsonima verbascifolia) hosts were sampled in a Neotropical savanna. Photosynthetic parameters, diurnal cycles of stomatal conductance, pre-dawn and midday leaf water potential, and stomatal anatomical traits were measured during the peak of the dry and wet seasons, respectively. P. ovata showed distinct water-use strategies that were dependent on host phenology. For P. ovata parasitizing the deciduous host, water use efficiency (WUE; ratio of photosynthetic rate to transpirational water loss) was 2-fold lower in the dry season than in the wet season; in contrast, WUE was maintained at the same level during the wet and dry seasons in P. ovata parasitizing the evergreen host. Generally, mistletoe and host diurnal cycles of stomatal conductance were linked, although there were clear differences in leaf water potential, with mistletoe showing anisohydric behaviour and the host showing isohydric behaviour. Compared to mistletoes attached to evergreen hosts, those parasitizing deciduous hosts had a 1.4-fold lower stomatal density and 1.2-fold wider stomata on both leaf surfaces, suggesting that the latter suffered less intense drought stress. This is the first study to show morphophysiological differences in the same mistletoe species parasitizing hosts of different phenological groups. Our results provide evidence that phenotypical plasticity (anatomical and physiological) might be essential to favour the use of a greater range of hosts. PMID:26686200

  18. Spectral radiance estimates of leaf area and leaf phytomass of small grains and native vegetation

    NASA Technical Reports Server (NTRS)

    Aase, J. K.; Brown, B. S.; Millard, J. P.

    1986-01-01

    Similarities and/or dissimilarities in radiance characteristics were studied among barley (Hordeum vulgare L.), oats (Avena fatua L.), spring and winter wheat (Triticum aestivum L.), and short-grass prairie vegetation. The site was a Williams loam soil (fine-loamy mixed, Typic Argiborolls) near Sidney, Montana. Radiances were measured with a truck-mounted radiometer. The radiometer was equipped with four wavelength bands: 0.45 to 0.52, 0.52 to 0.60, 0.63 to 0.69, and 0.76 to 0.90 micron. Airborne scanner measurements were made at an altitude of 600 m four times during the season under clear sky conditions. The airborne scanner was equipped with the same four bands as the truck-mounted radiometer plus the following: 1.00 to 1.30, 1.55 to 1.75, 2.08 to 2.35, and 10.4 to 12.5 microns. Comparisons using individual wave bands, the near IR/red, (0.76 to 0.90 micron)/(0.63 to 0.69 micron) ratio and the normalized difference vegetation index, ND = (IR - red)/(IR + red), showed that only during limited times during the growing season were some of the small grains distinguishable from one another and from native rangeland vegetation. There was a common relation for all small grains between leaf area index and green leaf phytomass and between leaf area index or green leaf phytomass and the IR/red ratio.

  19. Global variability in leaf respiration in relation to climate, plant functional types and leaf traits.

    PubMed

    Atkin, Owen K; Bloomfield, Keith J; Reich, Peter B; Tjoelker, Mark G; Asner, Gregory P; Bonal, Damien; Bönisch, Gerhard; Bradford, Matt G; Cernusak, Lucas A; Cosio, Eric G; Creek, Danielle; Crous, Kristine Y; Domingues, Tomas F; Dukes, Jeffrey S; Egerton, John J G; Evans, John R; Farquhar, Graham D; Fyllas, Nikolaos M; Gauthier, Paul P G; Gloor, Emanuel; Gimeno, Teresa E; Griffin, Kevin L; Guerrieri, Rossella; Heskel, Mary A; Huntingford, Chris; Ishida, Françoise Yoko; Kattge, Jens; Lambers, Hans; Liddell, Michael J; Lloyd, Jon; Lusk, Christopher H; Martin, Roberta E; Maksimov, Ayal P; Maximov, Trofim C; Malhi, Yadvinder; Medlyn, Belinda E; Meir, Patrick; Mercado, Lina M; Mirotchnick, Nicholas; Ng, Desmond; Niinemets, Ülo; O'Sullivan, Odhran S; Phillips, Oliver L; Poorter, Lourens; Poot, Pieter; Prentice, I Colin; Salinas, Norma; Rowland, Lucy M; Ryan, Michael G; Sitch, Stephen; Slot, Martijn; Smith, Nicholas G; Turnbull, Matthew H; VanderWel, Mark C; Valladares, Fernando; Veneklaas, Erik J; Weerasinghe, Lasantha K; Wirth, Christian; Wright, Ian J; Wythers, Kirk R; Xiang, Jen; Xiang, Shuang; Zaragoza-Castells, Joana

    2015-04-01

    Leaf dark respiration (Rdark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of Rdark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in Rdark . Area-based Rdark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, Rdark at a standard T (25°C, Rdark (25) ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher Rdark (25) at a given photosynthetic capacity (Vcmax (25) ) or leaf nitrogen concentration ([N]) than species at warmer sites. Rdark (25) values at any given Vcmax (25) or [N] were higher in herbs than in woody plants. The results highlight variation in Rdark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of Rdark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs). PMID:25581061

  20. D-Xylose as a sugar complement regulates blood glucose levels by suppressing phosphoenolpyruvate carboxylase (PEPCK) in streptozotocin-nicotinamide-induced diabetic rats and by enhancing glucose uptake in vitro

    PubMed Central

    Kim, Eunju; Kim, Yoo-Sun; Kim, Kyung-Mi; Jung, Sangwon; Yoo, Sang-Ho

    2016-01-01

    BACKGROUND/OBJECTIVES Type 2 diabetes (T2D) is more frequently diagnosed and is characterized by hyperglycemia and insulin resistance. D-Xylose, a sucrase inhibitor, may be useful as a functional sugar complement to inhibit increases in blood glucose levels. The objective of this study was to investigate the anti-diabetic effects of D-xylose both in vitro and stretpozotocin (STZ)-nicotinamide (NA)-induced models in vivo. MATERIALS/METHODS Wistar rats were divided into the following groups: (i) normal control; (ii) diabetic control; (iii) diabetic rats supplemented with a diet where 5% of the total sucrose content in the diet was replaced with D-xylose; and (iv) diabetic rats supplemented with a diet where 10% of the total sucrose content in the diet was replaced with D-xylose. These groups were maintained for two weeks. The effects of D-xylose on blood glucose levels were examined using oral glucose tolerance test, insulin secretion assays, histology of liver and pancreas tissues, and analysis of phosphoenolpyruvate carboxylase (PEPCK) expression in liver tissues of a STZ-NA-induced experimental rat model. Levels of glucose uptake and insulin secretion by differentiated C2C12 muscle cells and INS-1 pancreatic β-cells were analyzed. RESULTS In vivo, D-xylose supplementation significantly reduced fasting serum glucose levels (P < 0.05), it slightly reduced the area under the glucose curve, and increased insulin levels compared to the diabetic controls. D-Xylose supplementation enhanced the regeneration of pancreas tissue and improved the arrangement of hepatocytes compared to the diabetic controls. Lower levels of PEPCK were detected in the liver tissues of D-xylose-supplemented rats (P < 0.05). In vitro, both 2-NBDG uptake by C2C12 cells and insulin secretion by INS-1 cells were increased with D-xylose supplementation in a dose-dependent manner compared to treatment with glucose alone. CONCLUSIONS In this study, D-xylose exerted anti-diabetic effects in vivo by

  1. Diversity of Streptococcus salivarius ptsH Mutants That Can Be Isolated in the Presence of 2-Deoxyglucose and Galactose and Characterization of Two Mutants Synthesizing Reduced Levels of HPr, a Phosphocarrier of the Phosphoenolpyruvate:Sugar Phosphotransferase System

    PubMed Central

    Thomas, Suzanne; Brochu, Denis; Vadeboncoeur, Christian

    2001-01-01

    In streptococci, HPr, a phosphocarrier of the phosphoenolpyruvate:sugar phosphotransferase transport system (PTS), undergoes multiple posttranslational chemical modifications resulting in the formation of HPr(His∼P), HPr(Ser-P), and HPr(Ser-P)(His∼P), whose cellular concentrations vary with growth conditions. Distinct physiological functions are associated with specific forms of HPr. We do not know, however, the cellular thresholds below which these forms become unable to fulfill their functions and to what extent modifications in the cellular concentrations of the different forms of HPr modify cellular physiology. In this study, we present a glimpse of the diversity of Streptococcus salivarius ptsH mutants that can be isolated by positive selection on a solid medium containing 2-deoxyglucose and galactose and identify 13 amino acids that are essential for HPr to properly accomplish its physiological functions. We also report the characterization of two S. salivarius mutants that produced approximately two- and threefoldless HPr and enzyme I (EI) respectively. The data indicated that (i) a reduction in the synthesis of HPr due to a mutation in the Shine-Dalgarno sequence of ptsH reduced ptsI expression; (ii) a threefold reduction in EI and HPr cellular levels did not affect PTS transport capacity; (iii) a twofold reduction in HPr synthesis was sufficient to reduce the rate at which cells metabolized PTS sugars, increase generation times on PTS sugars and to a lesser extent on non-PTS sugars, and impede the exclusion of non-PTS sugars by PTS sugars; (iv) a threefold reduction in HPr synthesis caused a strong derepression of the genes coding for α-galactosidase, β-galactosidase, and galactokinase when the cells were grown at the expense of a PTS sugar but did not affect the synthesis of α-galactosidase when cells were grown at the expense of lactose, a noninducing non-PTS sugar; and (v) no correlation was found between the magnitude of enzyme derepression and

  2. Revealing catastrophic failure of leaf networks under stress.

    PubMed

    Brodribb, Timothy J; Bienaimé, Diane; Marmottant, Philippe

    2016-04-26

    The intricate patterns of veins that adorn the leaves of land plants are among the most important networks in biology. Water flows in these leaf irrigation networks under tension and is vulnerable to embolism-forming cavitations, which cut off water supply, ultimately causing leaf death. Understanding the ways in which plants structure their vein supply network to protect against embolism-induced failure has enormous ecological and evolutionary implications, but until now there has been no way of observing dynamic failure in natural leaf networks. Here we use a new optical method that allows the initiation and spread of embolism bubbles in the leaf network to be visualized. Examining embolism-induced failure of architecturally diverse leaf networks, we found that conservative rules described the progression of hydraulic failure within veins. The most fundamental rule was that within an individual venation network, susceptibility to embolism always increased proportionally with the size of veins, and initial nucleation always occurred in the largest vein. Beyond this general framework, considerable diversity in the pattern of network failure was found between species, related to differences in vein network topology. The highest-risk network was found in a fern species, where single events caused massive disruption to leaf water supply, whereas safer networks in angiosperm leaves contained veins with composite properties, allowing a staged failure of water supply. These results reveal how the size structure of leaf venation is a critical determinant of the spread of embolism damage to leaves during drought. PMID:27071104

  3. Senescent leaf exudate increases mosquito survival and microbial activity

    PubMed Central

    PELZ-STELINSKI, K. S.; WALKER, E. D.; KAUFMAN, M. G.

    2010-01-01

    We conducted experiments to evaluate the effects of soluble components in senescent leaf material on the growth and development of the eastern tree hole mosquito, Aedes triseriatus (Say). Oak leaves that were either leached for three days to remove the labile nutrient fraction, or were not leached, served as basal nutrient inputs in each experiment. Mosquito performance in microcosms containing leachate only was significantly worse compared with microcosms containing leaf material in combination with either leachate or water, indicating the importance of leaf substrates to mosquito production. Adult mosquito biomass, emergence, and development time were significantly higher in microcosms containing unleached leaves compared with leached leaf material. Additions of leachate to leached leaf treatments enhanced adult production, but not to the level observed in unleached leaf treatments. Filtered and unfiltered leachate added substantial nitrogen and phosphorus to microcosms and significantly affected mosquito growth responses. Bacterial productivity and abundance were also significantly affected by leachate additions and filtering. Taken together, these results suggest that while leaves decline with respect to nutritional value during decomposition, they remain important components of the habitat as substrates for microbial growth and mosquito feeding, particularly when nutrients (here, leachate) enter the system. Our results also illustrate the importance of soluble leaf material, which enhances mosquito production through effects on microbial community dynamics. PMID:21113430

  4. Genetic variability of Cotton leaf curl betasatellite in Northern India

    PubMed Central

    Sohrab, Sayed Sartaj; Azhar, Esam I.; Kamal, Mohammad A.; Bhattacharya, P.S.; Rana, D.

    2014-01-01

    Cotton is an important crop and its production is affected by various disease pathogens. Monopartite begomovirus associated betasatellites cause Cotton leaf curl disease (CLCuD) in Northern India. In order to access the occurrence and genetic variability of Cotton leaf curl betasatellites, an extensive field survey was conducted in states of Rajasthan, Punjab and Haryana. We selected the betasatellite sequence for analysis as they are reported as important for disease severity and sequence variability. Based on the field observations, the disease incidence ranged from 30% to 80% during the survey. Full genome and DNA β were amplified from various samples while no amplicon was obtained in some samples. The nucleotide sequence homology ranged from 90.0% to 98.7% with Cotton leaf curl virus (CLCuV), 55.2–55.5% with Bhendi yellow vein mosaic virus, 55.8% with Okra leaf curl virus and 51.70% with Tomato leaf curl virus isolates. The lowest similarity (47.8%) was found in CLCuV-Sudan isolate. Phylogenetic analysis showed that analyzed isolates formed a close cluster with various CLCuV isolates reported earlier. The analysis results show sequence variation in Cotton leaf curl betasatellite which could be the result of recombination. The results obtained by genome amplification and sequence variability indicate that some new variants are circulating and causing leaf curl disease in Rajasthan, Punjab and Haryana. PMID:25473373

  5. Leaf surfaces and the bioavailability of pesticide residues.

    PubMed

    Chowdhury, A B; Jepson, P C; Howse, P E; Ford, M G

    2001-05-01

    Laboratory bioassays were carried out to determine the toxicity to Folsomia candida Willem (Collembola: Isotomidae) of residues of a pyrethroid insecticide, deltamethrin, and an organophosphorus insecticide, dimethoate, on different leaf surfaces. The test leaves included a range of species and leaves of different ages. Dose-response relationships were estimated for F candida walking over the various treated leaf substrates. Probit analysis was used to estimate the means and standard deviations of the associated tolerance distributions expressed as gAIha-1. Parallelism tests were undertaken to compare the susceptibilities of F candida to the two compounds applied to the different leaf surfaces. On deltamethrin-treated leaf surfaces, the LD50 values for F candida varied from 6.36 to 77.14 gAIha-1. F candida was least susceptible to deltamethrin residues when applied to leaves of dwarf bean (Phaseolus vulgarus L) and the highest susceptibility was observed following application to leaves of seedlings of barley (Hordeum vulgare L). In contrast, the LD50 values observed for dimethoate treatments did not differ significantly between leaf types, ranging from 1.35 to 8.69 gAIha-1. The laboratory data on susceptibility of F candida on different leaf types for different pesticides can be used to investigate the role of leaf surface properties in modifying the toxicity of applied pesticides to exposed invertebrates. PMID:11374156

  6. Genetic variability of Cotton leaf curl betasatellite in Northern India.

    PubMed

    Sohrab, Sayed Sartaj; Azhar, Esam I; Kamal, Mohammad A; Bhattacharya, P S; Rana, D

    2014-12-01

    Cotton is an important crop and its production is affected by various disease pathogens. Monopartite begomovirus associated betasatellites cause Cotton leaf curl disease (CLCuD) in Northern India. In order to access the occurrence and genetic variability of Cotton leaf curl betasatellites, an extensive field survey was conducted in states of Rajasthan, Punjab and Haryana. We selected the betasatellite sequence for analysis as they are reported as important for disease severity and sequence variability. Based on the field observations, the disease incidence ranged from 30% to 80% during the survey. Full genome and DNA β were amplified from various samples while no amplicon was obtained in some samples. The nucleotide sequence homology ranged from 90.0% to 98.7% with Cotton leaf curl virus (CLCuV), 55.2-55.5% with Bhendi yellow vein mosaic virus, 55.8% with Okra leaf curl virus and 51.70% with Tomato leaf curl virus isolates. The lowest similarity (47.8%) was found in CLCuV-Sudan isolate. Phylogenetic analysis showed that analyzed isolates formed a close cluster with various CLCuV isolates reported earlier. The analysis results show sequence variation in Cotton leaf curl betasatellite which could be the result of recombination. The results obtained by genome amplification and sequence variability indicate that some new variants are circulating and causing leaf curl disease in Rajasthan, Punjab and Haryana. PMID:25473373

  7. Auxin depletion from leaf primordia contributes to organ patterning

    PubMed Central

    Qi, Jiyan; Wang, Ying; Yu, Ting; Cunha, Alexandre; Wu, Binbin; Vernoux, Teva; Meyerowitz, Elliot; Jiao, Yuling

    2014-01-01

    Stem cells are responsible for organogenesis, but it is largely unknown whether and how information from stem cells acts to direct organ patterning after organ primordia are formed. It has long been proposed that the stem cells at the plant shoot apex produce a signal, which promotes leaf adaxial-abaxial (dorsoventral) patterning. Here we show the existence of a transient low auxin zone in the adaxial domain of early leaf primordia. We also demonstrate that this adaxial low auxin domain contributes to leaf adaxial-abaxial patterning. The auxin signal is mediated by the auxin-responsive transcription factor MONOPTEROS (MP), whose constitutive activation in the adaxial domain promotes abaxial cell fate. Furthermore, we show that auxin flow from emerging leaf primordia to the shoot apical meristem establishes the low auxin zone, and that this auxin flow contributes to leaf polarity. Our results provide an explanation for the hypothetical meristem-derived leaf polarity signal. Opposite to the original proposal, instead of a signal derived from the meristem, we show that a signaling molecule is departing from the primordium to the meristem to promote robustness in leaf patterning. PMID:25512543

  8. Predicting leaf traits of herbaceous species from their spectral characteristics

    PubMed Central

    Roelofsen, Hans D; van Bodegom, Peter M; Kooistra, Lammert; Witte, Jan-Philip M

    2014-01-01

    Trait predictions from leaf spectral properties are mainly applied to tree species, while herbaceous systems received little attention in this topic. Whether similar trait–spectrum relations can be derived for herbaceous plants that differ strongly in growing strategy and environmental constraints is therefore unknown. We used partial least squares regression to relate key traits to leaf spectra (reflectance, transmittance, and absorbance) for 35 herbaceous species, sampled from a wide range of environmental conditions. Specific Leaf Area and nutrient-related traits (N and P content) were poorly predicted from any spectrum, although N prediction improved when expressed on a per area basis (mg/m2 leaf surface) instead of mass basis (mg/g dry matter). Leaf dry matter content was moderately to good correlated with spectra. We explain our results by the range of environmental constraints encountered by herbaceous species; both N and P limitations as well as a range of light and water availabilities occurred. This weakened the relation between the measured response traits and the leaf constituents that are truly responsible for leaf spectral behavior. Indeed, N predictions improve considering solely upper or under canopy species. Therefore, trait predictions in herbaceous systems should focus on traits relating to dry matter content and the true, underlying drivers of spectral properties. PMID:24683454

  9. Effects of wind speed on leaf energy and gas exchange

    NASA Astrophysics Data System (ADS)

    Schymanski, Stanislaus J.; Or, Dani

    2013-04-01

    The common practice of modelling transpiration from plant leaves as an isothermal process (assuming equal leaf and air temperatures) may introduce significant bias into estimates of transpiration rates and energy partitioning. In a recent study (Schymanski et al., 2013, PLOS ONE, in print) we investigated effects of fluctuating irradiance (sunflecks) on leaf thermal regime and transpiration rates using a physically-based leaf model. Results suggest that leaf temperatures may deviate substantially from air temperature, leading to greatly modified transpiration rates compared to isothermal conditions, even under steady-state conditions. The results also highlighted the importance of intrinsic thermal protection imparted by transpiration flux. In this study we consider leaf energy balance to systematically investigate effects of wind speed on plant heat and gas exchange. Surprisingly, under certain conditions increasing wind speeds can result in a decrease in transpiration rates. This is due to the feedbacks between sensible heat flux, leaf temperature and latent heat flux. The model predicts that for high wind velocities the same leaf conductance (for water vapour and carbon dioxide) can be maintained with less evaporative losses. This may have profound implications for estimates of water use efficiency (WUE, the amount of carbon gained by photosynthesis per unit of water lost by transpiration), and the interpretation of changes in "Potential Evaporation" in relation to plant water use.

  10. Genetic, molecular, and morphological analysis of compound leaf development.

    PubMed

    Goliber, T; Kessler, S; Chen, J J; Bharathan, G; Sinha, N

    1999-01-01

    Leaves, the plant organs responsible for capturing and converting most of the 170 billion metric tons of carbon fixed globally each year, can be broadly grouped into two morphological categories: simple and compound. Although simple-leaved species such as corn and Arabidopsis have traditionally been favored model systems for studying leaf development, recent years have seen an increase in genetic and molecular studies of compound leaf development. Two compound-leaved species in particular have emerged as model systems: tomato and pea. A variety of mutations which alter leaf morphology in these species have been described, and analyses of these mutations have allowed the construction of testable models of leaf development. Also, the knotted-like homeobox (KNOX) genes, which were originally discovered as regulators of meristem function, now appear to have a role in compound leaf development. In addition to the recent genetic and molecular analyses of tomato and pea, insight into the nature of compound leaf development may be gained through the study of (a) heteroblasty and heterophylly, phenomena in which a range of leaf forms can be produced by a single shoot, and (b) the evolutionary origins of compound leaves. PMID:9891889

  11. Droplet Impacting a Cantilever: A Leaf-Raindrop System

    NASA Astrophysics Data System (ADS)

    Gart, Sean; Mates, Joseph E.; Megaridis, Constantine M.; Jung, Sunghwan

    2015-04-01

    Previous studies show that air pollution and wind erosion, which damage a leaf's epicuticular wax layer, can change leaf surface properties from hydrophobic to hydrophilic. However, the dynamic response of a damaged leaf to a raindrop impact has not been investigated and could clarify the direct influence of changes in wettability on early leaf abscission. In this article, we investigate how leaves with different surface properties respond to falling raindrops, viewing this as a unique system of coupled elasticity and drop dynamics. An elastic beam with tunable surface wettability properties is used as a simple leaf model. We find that wettable beams experience much higher torque and bending energy than nonwettable beams. This is because a drop sticks to a wettable beam, while a drop falls off a nonwettable beam. An analytical model using momentum balance and simple cantilever beam theory quantifies the bending energy and torque experienced by wettable and nonwettable beams. The results elucidate the potential damage caused by raindrops impacting a leaf as a function of its surface wettability and are correlated with environmental factors contributing to premature changes of leaf surface properties.

  12. Auxin depletion from leaf primordia contributes to organ patterning.

    PubMed

    Qi, Jiyan; Wang, Ying; Yu, Ting; Cunha, Alexandre; Wu, Binbin; Vernoux, Teva; Meyerowitz, Elliot; Jiao, Yuling

    2014-12-30

    Stem cells are responsible for organogenesis, but it is largely unknown whether and how information from stem cells acts to direct organ patterning after organ primordia are formed. It has long been proposed that the stem cells at the plant shoot apex produce a signal, which promotes leaf adaxial-abaxial (dorsoventral) patterning. Here we show the existence of a transient low auxin zone in the adaxial domain of early leaf primordia. We also demonstrate that this adaxial low auxin domain contributes to leaf adaxial-abaxial patterning. The auxin signal is mediated by the auxin-responsive transcription factor MONOPTEROS (MP), whose constitutive activation in the adaxial domain promotes abaxial cell fate. Furthermore, we show that auxin flow from emerging leaf primordia to the shoot apical meristem establishes the low auxin zone, and that this auxin flow contributes to leaf polarity. Our results provide an explanation for the hypothetical meristem-derived leaf polarity signal. Opposite to the original proposal, instead of a signal derived from the meristem, we show that a signaling molecule is departing from the primordium to the meristem to promote robustness in leaf patterning. PMID:25512543

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

    PubMed

    Ding, Risheng; Kang, Shaozhong; Du, Taisheng; Hao, Xinmei; Zhang, Yanqun

    2014-01-01

    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 partitioning

  14. Optimal Leaf Positions for SPAD Meter Measurement in Rice

    PubMed Central

    Yuan, Zhaofeng; Cao, Qiang; Zhang, Ke; Ata-Ul-Karim, Syed Tahir; Tian, Yongchao; Zhu, Yan; Cao, Weixing; Liu, Xiaojun

    2016-01-01

    The Soil Plant Analysis Development (SPAD) chlorophyll meter is one of the most commonly used diagnostic tools to measure crop nitrogen status. However, the measurement method of the meter could significantly affect the accuracy of the final estimation. Thus, this research was undertaken to develop a new methodology to optimize SPAD meter measurements in rice (Oryza sativa L.). A flatbed color scanner was used to map the dynamic chlorophyll distribution and irregular leaf shapes. Calculus algorithm was adopted to estimate the potential positions for SPAD meter measurement along the leaf blade. Data generated by the flatbed color scanner and SPAD meter were analyzed simultaneously. The results suggested that a position 2/3 of the distance from the leaf base to the apex (2/3 position) could represent the chlorophyll content of the entire leaf blade, as indicated by the relatively low variance of measurements at that position. SPAD values based on di-positional leaves and the extracted chlorophyll a and b contents were compared. This comparison showed that the 2/3 position on the lower leaves tended to be more sensitive to changes in chlorophyll content. Finally, the 2/3 position and average SPAD values of the fourth fully expanded leaf from the top were compared with leaf nitrogen concentration. The results showed the 2/3 position on that leaf was most suitable for predicting the nitrogen status of rice. Based on these results, we recommend making SPAD measurements at the 2/3 position on the fourth fully expanded leaf from the top. The coupling of dynamic chlorophyll distribution and irregular leaf shapes information can provide a promising approach for the calibration of SPAD meter measurement, which can further benefit the in situ nitrogen management by providing reliable estimation of crops nitrogen nutrition status. PMID:27303416

  15. Influences of Environmental Factors on Leaf Morphology of Chinese Jujubes

    PubMed Central

    Li, Xiaopeng; Li, Yupeng; Zhang, Zhong; Li, Xingang

    2015-01-01

    Rainfall and temperature are the primary limiting factors for optimum quality and yield of cultivated jujube (Ziziphus jujuba Mill.). Adaptation to arid and cool environments has been and remains an important goal of many jujube improvement programs. This study summarized the survey results of 116 Chinese jujube varieties grown at 33 sites in China. The objective was to identify the environmental factors that influence leaf morphology, and the implications for breeding and introduction of new jujube varieties. Jujube leaf morphological traits were evaluated for their potential relationships with mean annual temperature (MAT) and mean annual precipitation (MAP). The results showed that many leaf morphological traits had a strong linear relationship with local precipitation and temperature. Longer veins per unit area (VLA) and reduced leaf area and leaf perimeter were typical of arid areas. VLA was inversely related to MAT and MAP at the centers of origin of jujube. There was a positive relationship between leaf shape (perimeter2/area) and both MAT and MAP. These results indicated that leaf vein traits of Chinese jujubes might have resulted from their adaptation to environmental factors in the course of long-term evolution. Principal component analysis allocated the 116 jujube varieties to three different groups, differentiated on the basis of morphological and physiological leaf characteristics. Jujube varieties from the Hebei, Shandong, Henan, southern Shanxi and central Shaanxi provinces were closely related, as were varieties from northwest Shanxi and northeast Shaanxi provinces, and varieties from the Gansu and Ningxia provinces. These close relationships were partially attributed to the frequent exchanges of varieties within each group. Leaf venation characteristics might be used as reference indices for jujube variety introduction between different locations. PMID:26020971

  16. Optimal Leaf Positions for SPAD Meter Measurement in Rice.

    PubMed

    Yuan, Zhaofeng; Cao, Qiang; Zhang, Ke; Ata-Ul-Karim, Syed Tahir; Tian, Yongchao; Zhu, Yan; Cao, Weixing; Liu, Xiaojun

    2016-01-01

    The Soil Plant Analysis Development (SPAD) chlorophyll meter is one of the most commonly used diagnostic tools to measure crop nitrogen status. However, the measurement method of the meter could significantly affect the accuracy of the final estimation. Thus, this research was undertaken to develop a new methodology to optimize SPAD meter measurements in rice (Oryza sativa L.). A flatbed color scanner was used to map the dynamic chlorophyll distribution and irregular leaf shapes. Calculus algorithm was adopted to estimate the potential positions for SPAD meter measurement along the leaf blade. Data generated by the flatbed color scanner and SPAD meter were analyzed simultaneously. The results suggested that a position 2/3 of the distance from the leaf base to the apex (2/3 position) could represent the chlorophyll content of the entire leaf blade, as indicated by the relatively low variance of measurements at that position. SPAD values based on di-positional leaves and the extracted chlorophyll a and b contents were compared. This comparison showed that the 2/3 position on the lower leaves tended to be more sensitive to changes in chlorophyll content. Finally, the 2/3 position and average SPAD values of the fourth fully expanded leaf from the top were compared with leaf nitrogen concentration. The results showed the 2/3 position on that leaf was most suitable for predicting the nitrogen status of rice. Based on these results, we recommend making SPAD measurements at the 2/3 position on the fourth fully expanded leaf from the top. The coupling of dynamic chlorophyll distribution and irregular leaf shapes information can provide a promising approach for the calibration of SPAD meter measurement, which can further benefit the in situ nitrogen management by providing reliable estimation of crops nitrogen nutrition status. PMID:27303416

  17. Plasticity in sunflower leaf and cell growth under high salinity.

    PubMed

    Céccoli, G; Bustos, D; Ortega, L I; Senn, M E; Vegetti, A; Taleisnik, E

    2015-01-01

    A group of sunflower lines that exhibit a range of leaf Na(+) concentrations under high salinity was used to explore whether the responses to the osmotic and ionic components of salinity can be distinguished in leaf expansion kinetics analysis. It was expected that at the initial stages of the salt treatment, leaf expansion kinetics changes would be dominated by responses to the osmotic component of salinity, and that later on, ion inclusion would impose further kinetics changes. It was also expected that differential leaf Na(+) accumulation would be reflected in specific changes in cell division and expansion rates. Plants of four sunflower lines were gradually treated with a relatively high (130 mm NaCl) salt treatment. Leaf expansion kinetics curves were compared in leaves that were formed before, during and after the initiation of the salt treatment. Leaf areas were smaller in salt-treated plants, but the analysis of growth curves did not reveal differences that could be attributed to differential Na(+) accumulation, since similar changes in leaf expansion kinetics were observed in lines with different magnitudes of salt accumulation. Nevertheless, in a high leaf Na(+) -including line, cell divisions were affected earlier, resulting in leaves with proportionally fewer cells than in a Na(+) -excluding line. A distinct change in leaf epidermal pavement shape caused by salinity is reported for the first time. Mature pavement cells in leaves of control plants exhibited typical lobed, jigsaw-puzzle shape, whereas in treated plants, they tended to retain closer-to-circular shapes and a lower number of lobes. PMID:24942979

  18. Remote sensing of leaf N to improve carbon assimilation prediction

    NASA Astrophysics Data System (ADS)

    Loozen, Yasmina; Rebel, Karin; Karssenberg, Derek; de Jong, Steven; Wassen, Martin

    2016-04-01

    Predicting and understanding carbon assimilation by terrestrial vegetation remains fundamental in the context of climate change. Carbon and nitrogen cycles are linked as nitrogen is an essential nutrient for plant growth. In this respect the N cycle is integrated into vegetation models predicting vegetation carbon uptake. However plant traits within the N cycle, such as leaf nitrogen, are lacking at large scales, which complicates the calibration and optimization of the N cycling modelling modules. Remote sensing techniques could offer the possibility to detect leaf N concentration at continental scales. In fact, it has already been used to sense leaf N at local, e.g. in agricultural oriented applications, as well as at regional scales. The objective of this study is to enhance the availability of leaf N estimates in forested ecosystems at European scale using remote sensing products. European forest leaf N data were obtained from the TRY database. The MERIS Terrestrial chlorophyll Index (MTCI) Level 3 product as well as two reflectance bands in the NIR region (band centers at 865 and 885nm) both from MERIS aboard ENVISAT (ESA) were used to study statistical relationship with leaf N data. In a first step, we analyzed 1892 Catalonian (NE Spain) forest plots using a linear regression method. The regressions results between leaf N and either MTCI or NIR bands were significant (p< 0.001). The R-square for the regression between leaf N and MTCI was equal to 0.13. The method performed better for broadleaves deciduous plots (R-square = 0.11) than for needleleaves or broadleaves evergreen plots. The relationship between leaf N and MTCI was also higher for the plots sampled during summer (R-square = 0.28 in July) than for the plots sampled during the rest of the year. In a second step the method will be applied on and will include more diverse forest types at the European level.

  19. Coca Leaf and Cocaine Addiction: Some Historical Notes

    PubMed Central

    Blejer-Prieto, H.

    1965-01-01

    Coca-leaf habituation has affected millions of Andean natives for over 400 years. In the last half-century it has also involved millions more Malayans. Coca leaf, from which cocaine and extracts for some commercial carbonated soft drinks are obtained, remains relatively unknown by the medical and allied professions elsewhere. A review of the original medical, historical and other pertinent literature of the last 350 years illustrates the origins of the use of coca leaf, its spread, the isolation of cocaine and its first uses, as well as some of the euphoric and other effects of both substances. PMID:5318484

  20. Effect of curvature on the backscattering from a leaf

    NASA Technical Reports Server (NTRS)

    Sarabandi, K.; Senior, T. B. A.; Ulaby, F. T.

    1988-01-01

    Using a model previously developed for the backscattering cross section of a planar leaf at X-band frequencies and above, the effect of leaf curvature is examined. For normal incidence on a rectangular section of a leaf curved in one and two dimensions, an integral expression for the backscattered field is evaluated numerically and by a stationary phase approximation, leading to a simple analytical expression for the cross-section reduction produced by the curvature. Numerical results based on the two methods are virtually identical, and in excellent agreement with measured data for rectangular sections of coleus leaves applied to the surfaces of styrofoam cylinders and spheres of different radii.