Sample records for spinach leaf sucrose-phosphate

  1. Transgenic cotton over-producing spinach sucrose phosphate synthase showed enhanced leaf sucrose synthesis and improved

    E-print Network

    Strauss, Richard E.

    , and development of enhanced extractable Vmax SPS activ- ity in leaf and fiber. Lines with the highest Vmax SPSTransgenic cotton over-producing spinach sucrose phosphate synthase showed enhanced leaf sucrose activity in leaf and fiber had higher fiber micro- naire and maturity ratio associated with greater thick

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  3. Site-specific regulatory interaction between spinach leaf sucrose-phosphate synthase and 14-3-3 proteins

    NASA Technical Reports Server (NTRS)

    Toroser, D.; Athwal, G. S.; Huber, S. C.; Davies, E. (Principal Investigator)

    1998-01-01

    We report an Mg2+-dependent interaction between spinach leaf sucrose-phosphate synthase (SPS) and endogenous 14-3-3 proteins, as evidenced by co-elution during gel filtration and co-immunoprecipitation. The content of 14-3-3s associated with an SPS immunoprecipitate was inversely related to activity, and was specifically reduced when tissue was pretreated with 5-aminoimidazole-4-carboxamide riboside, suggesting metabolite control in vivo. A synthetic phosphopeptide based on Ser-229 was shown by surface plasmon resonance to bind a recombinant plant 14-3-3, and addition of the phosphorylated SPS-229 peptide was found to stimulate the SPS activity of an SPS:14-3-3 complex. Taken together, the results suggest a regulatory interaction of 14-3-3 proteins with Ser-229 of SPS.

  4. Transgenic cotton over-producing spinach sucrose phosphate synthase showed enhanced leaf sucrose synthesis and improved fiber quality under controlled environmental conditions

    Microsoft Academic Search

    Candace H. Haigler; Bir Singh; Deshui Zhang; Sangjoon Hwang; Chunfa Wu; Wendy X. Cai; Mohamed Hozain; Wonhee Kang; Brett Kiedaisch; Richard E. Strauss; Eric F. Hequet; Bobby G. Wyatt; Gay M. Jividen; A. Scott Holaday

    2007-01-01

    Prior data indicated that enhanced availability of sucrose, a major product of photosynthesis in source leaves and the carbon\\u000a source for secondary wall cellulose synthesis in fiber sinks, might improve fiber quality under abiotic stress conditions.\\u000a To test this hypothesis, a family of transgenic cotton plants (Gossypium\\u000a hirsutum cv. Coker 312 elite) was produced that over-expressed spinach sucrose-phosphate synthase (SPS)

  5. Possible Control of Maize Leaf Sucrose-Phosphate Synthase Activity by Light Modulation

    PubMed Central

    Sicher, Richard C.; Kremer, Diane F.

    1985-01-01

    Sucrose phosphate synthase (SPS) activity was measured in extracts of maize (Zea mays L.) and soybean (Glycine max L. [Merr.]) leaves over a single day/night cycle. There was a 2- to 3-fold postillumination increase in extractable enzyme activity in maize leaves, whereas the activity of soybean SPS was only about 30% higher in extracts prepared from light- compared to dark-adapted leaves. Alterations in extractable maize leaf SPS activity correlated with light/dark transitions suggesting that the enzyme may be light modulated. Diurnal variations of extractable maize leaf SPS activity were also observed in a greenhouse experiment. A transition from high (light) to low (dark) extractable SPS activity occurred near the light compensation point for photosynthesis (about 20 micromole photons per square meter per second). Further increases in irradiance did not increase extractable SPS activity. Substrate affinities for uridine 5?-diphosphoglucose (Michaelis constant = 3.5 and 5.1 millimolar) and fructose-6 phosphate (half maximal concentration = 1.0 and 2.5 millimolar) were lower for partially purified SPS obtained from light compared to dark acclimated maize leaves. Light-induced changes in extractable SPS activity were stable for at least one column chromatography step. The above results indicate that light-induced changes in SPS activity may be important in controlling the photosynthetic production of sucrose. PMID:16664475

  6. SCREENING FOR RESISTANCE TO STEMPHYLIUM LEAF SPOT OF SPINACH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf spot disease of spinach (Spinacia oleracea L.) caused by Stemphylium botryosum has continued to occur in California and six other states since 1997, posing another challenge for growers to produce high quality and defect-free products. No resistance to the pathogen has been reported in spinach....

  7. Screening for Resistance to Leaf Spot Diseases of Spinach.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf spot of spinach (Spinacia oleracea L.) caused by Stemphylium botryosum has continued to occur in California and at least six other states since 1997, posing yet another challenge for growers to produce high quality and defect-free products. Resistance to the pathogen has not been reported in sp...

  8. Studies on sucrose-phosphate synthase from rice leaves.

    PubMed

    Salerno, G L; Pagnussat, G C; Pontis, H G

    1998-05-01

    Sucrose-phosphate synthase (SPS, EC 2.4.1.14) biochemical properties and peptide composition have been analyzed in rice leaf seedlings. SPS was purified using DEAE-Sephacel chromatography, gel filtration on Sepharose 6B and anion exchange chromatography on Mono Q. At this stage two enzyme forms (SPS-I and -II) were separated. SPS-II was purified 90-fold; however, SPS-I presented a lower specific activity regarding the previous purification step and an unstable activity. Both enzyme forms had similar apparent Km values for Fru-6P but the SPS-I Km for UDP-Glc was ca. 10-fold higher than the SPS-II one. In addition, they differentiate in the capacity of being modulated by Glc-6-P and Pi: while SPS-II activity was inhibited by Pi and activated by Glc-6-P, SPS-I was not affected by either effectors. A native molecular mass of ca. 420 kDa was found by gel filtration. In SPS expression analysis using leaf rice and wheat germ SPS antibodies, a 116 kDa polypeptide was revealed in rice leaf extracts and no polypeptide was immunoactive in rice roots. PMID:9620436

  9. Antioxidant capacity and phenolic content in leaf extracts of tree spinach (Cnidoscolus spp.).

    PubMed

    Kuti, Joseph O; Konuru, Hima B

    2004-01-14

    Total phenolic content and antioxidant capacity of two tree spinach species (Cnidoscolus chayamansa McVaugh and C. aconitifolius Miller.) were determined in raw and cooked leaf extracts. Antioxidant capacity was assessed by the oxygen radical absorbance capacity (ORAC) assay, and flavonoid glycoside composition was quantified by HPLC and identified by GC. Total phenolics and antioxidant capacity were higher in raw than in cooked leaf extracts. The ORAC values were strongly correlated with total phenolic content (r = 0.926) in all leaf extracts. The major flavonoids isolated from the leaf extracts were kaempferol-3-O-glycosides and quercetin-3-O-glycosides. C. aconitifolius leaves contained more varieties of the flavonoid glycosides than C. chayamansa. Cooking reduced antioxidant activity and phenolic content and resulted in losses of some kaempferol glycoside and quercetin glycoside residues in leaf extracts. The results of this study indicate that tree spinach leaves are a rich source of natural antioxidants for foods. PMID:14709023

  10. Abscisic acid accumulation in spinach leaf slices in the presence of penetrating and nonpenetrating solutes

    SciTech Connect

    Creelman, R.A.; Zeevaart, J.A.D.

    1985-01-01

    Abscisic acid (ABA) accumulated in detached, wilted leaves of spinach (Spinacia oleracea L. cv Savoy Hybrid 612) and reached a maximum level within 3 to 4 hours. The increase in ABA over that found in detached turgid leaves was approximately 10-fold. The effects of water stress could be mimicked by the use of thin slices of spinach leaves incubated in the presence of 0.6 molar mannitol, a compound which causes plasmolysis (loss of turgor). When spinach leaf slices were incubated with ethylene glycol, a compound which rapidly penetrates the cell membrane causing a decrease in the osmotic potential of the tissue and only transient loss of turgor, no ABA accumulated. Spinach leaf slices incubated in both ethylene glycol and mannitol had ABA levels similar to those found when slices were incubated with mannitol alone. Increases similar to those found with mannitol also occurred when Aquacide III, a highly purified form of polyethylene glycol, was used. When spinach leaf slices were incubated with solutes which are supposed to disturb membrane integrity no increase in ABA was observed. These data indicate that, with respect to the accumulation of ABA, mannitol caused a physical stress rather than a chemical stress.

  11. Loss of the two major leaf isoforms of sucrose-phosphate synthase in Arabidopsis thaliana limits sucrose synthesis and nocturnal starch degradation but does not alter carbon partitioning during photosynthesis.

    PubMed

    Volkert, Kathrin; Debast, Stefan; Voll, Lars M; Voll, Hildegard; Schießl, Ingrid; Hofmann, Jörg; Schneider, Sabine; Börnke, Frederik

    2014-10-01

    Sucrose (Suc)-phosphate synthase (SPS) catalyses one of the rate-limiting steps in the synthesis of Suc in plants. The Arabidopsis genome contains four annotated SPS genes which can be grouped into three different families (SPSA1, SPSA2, SPSB, and SPSC). However, the functional significance of this multiplicity of SPS genes is as yet only poorly understood. All four SPS isoforms show enzymatic activity when expressed in yeast although there is variation in sensitivity towards allosteric effectors. Promoter-reporter gene analyses and quantitative real-time reverse transcription-PCR studies indicate that no two SPS genes have the same expression pattern and that AtSPSA1 and AtSPSC represent the major isoforms expressed in leaves. An spsa1 knock-out mutant showed a 44% decrease in leaf SPS activity and a slight increase in leaf starch content at the end of the light period as well as at the end of the dark period. The spsc null mutant displayed reduced Suc contents towards the end of the photoperiod and a concomitant 25% reduction in SPS activity. In contrast, an spsa1/spsc double mutant was strongly impaired in growth and accumulated high levels of starch. This increase in starch was probably not due to an increased partitioning of carbon into starch, but was rather caused by an impaired starch mobilization during the night. Suc export from excised petioles harvested from spsa1/spsc double mutant plants was significantly reduced under illumination as well as during the dark period. It is concluded that loss of the two major SPS isoforms in leaves limits Suc synthesis without grossly changing carbon partitioning in favour of starch during the light period but limits starch degradation during the dark period. PMID:24994761

  12. Sucrose Phosphate Is Not Transported into Vacuoles or Tonoplast Vesicles from Red Beet (Beta vulgaris) Hypocotyl.

    PubMed

    Echeverria, E; Salvucci, M E

    1991-08-01

    Tonoplast vesicles and vacuoles isolated from red beet (Beta vulgaris L.) hypocotyl accumulated externally supplied [(14)C]sucrose but not [(14)C]sucrose phosphate despite the occurrence of sucrose phosphate phosphohydrolytic activity in the vacuole. The activities of sucrose synthase and sucrose phosphate synthase in whole cell extracts were 960 and 30 nanomoles per milligram protein per minute, respectively; whereas, no sucrose synthesizing activity was measured in tonoplast preparations. The results obtained in this investigation are incompatible with the involvement of sucrose phosphate synthase in the process of sucrose synthesis and accumulation in the storage cells of red beet. PMID:16668291

  13. Sucrose phosphate synthase and sucrose phosphate phosphatase interact in planta and promote plant growth and biomass accumulation

    PubMed Central

    Maloney, Victoria J.; Park, Ji-Young; Unda, Faride; Mansfield, Shawn D.

    2015-01-01

    Bioinformatic analysis indicates that sucrose phosphate synthase (SPS) contains a putative C-terminal sucrose phosphate phosphatase (SPP)-like domain that may facilitates the binding of SPP. If an SPS–SPP enzyme complex exists, it may provide sucrose biosynthesis with an additional level of regulation, forming a direct metabolic channel for sucrose-6-phosphate between these two enzymes. Herein, the formation of an enzyme complex between SPS and SPP was examined, and the results from yeast two-hybrid experiments suggest that there is indeed an association between these proteins. In addition, in planta bioluminescence resonance energy transfer (BRET) was observed in Arabidopsis seedlings, providing physical evidence for a protein interaction in live cells and in real time. Finally, bimolecular fluorescence complementation (BiFC) was employed in an attempt to detect SPS–SPP interactions visually. The findings clearly demonstrated that SPS interacts with SPP and that this interaction impacts soluble carbohydrate pools and affects carbon partitioning to starch. Moreover, a fusion construct between the two genes promotes plant growth in both transgenic Arabidopsis and hybrid poplar. PMID:25873678

  14. Sucrose phosphate synthase and sucrose phosphate phosphatase interact in planta and promote plant growth and biomass accumulation.

    PubMed

    Maloney, Victoria J; Park, Ji-Young; Unda, Faride; Mansfield, Shawn D

    2015-07-01

    Bioinformatic analysis indicates that sucrose phosphate synthase (SPS) contains a putative C-terminal sucrose phosphate phosphatase (SPP)-like domain that may facilitates the binding of SPP. If an SPS-SPP enzyme complex exists, it may provide sucrose biosynthesis with an additional level of regulation, forming a direct metabolic channel for sucrose-6-phosphate between these two enzymes. Herein, the formation of an enzyme complex between SPS and SPP was examined, and the results from yeast two-hybrid experiments suggest that there is indeed an association between these proteins. In addition, in planta bioluminescence resonance energy transfer (BRET) was observed in Arabidopsis seedlings, providing physical evidence for a protein interaction in live cells and in real time. Finally, bimolecular fluorescence complementation (BiFC) was employed in an attempt to detect SPS-SPP interactions visually. The findings clearly demonstrated that SPS interacts with SPP and that this interaction impacts soluble carbohydrate pools and affects carbon partitioning to starch. Moreover, a fusion construct between the two genes promotes plant growth in both transgenic Arabidopsis and hybrid poplar. PMID:25873678

  15. Structural characterization of two aquaporins isolated from native spinach leaf plasma membranes.

    PubMed

    Fotiadis, D; Jenö, P; Mini, T; Wirtz, S; Müller, S A; Fraysse, L; Kjellbom, P; Engel, A

    2001-01-19

    Two members of the aquaporin family, PM28A and a new one, PM28C, were isolated and shown to be the major constituents of spinach leaf plasma membranes. These two isoforms were identified and characterized by matrix-assisted laser desorption ionization-mass spectrometry. Edman degradation yielded the amino acid sequence of two domains belonging to the new isoform. PM28B, a previously described isoform, was not found in our preparations. Scanning transmission electron microscopy mass analysis revealed both PM28 isoforms to be tetrameric. Two types of particles, a larger and a smaller one, were found by transmission electron microscopy of negatively stained solubilized proteins and by atomic force microscopy of PM28 two-dimensional crystals. The ratio of larger to smaller particles observed by transmission electron microscopy and single particle analysis correlated with the ratio of PM28A to PM28C determined by matrix-assisted laser desorption ionization-mass spectrometry. The absence of PM28B and the ratio of PM28A to PM28C indicate that these plasma membrane intrinsic proteins are differentially expressed in spinach leaves. These findings suggest that differential expression of the various aquaporin isoforms may regulate the water flux across the plasma membrane, in addition to the known mechanism of regulation by phosphorylation. PMID:11050104

  16. Sucrose phosphate synthase activity in rice grown at elevated CO sub 2 and temperature

    SciTech Connect

    Hussain, W.; Rowland-Bamford, A.J.; Baker, J.T.; Allen, L.H. Jr.; Bowes, G. (Univ. of Florida, Gainesville (USA) USDA-ARS, Gainesville, FL (USA))

    1990-05-01

    Rice (Oryza sativa L.) was grown at 330 and 660 {mu}L CO{sub 2} L{sup {minus}1} and at 40/33/37, 34/27/31, and 28/21/25{degree}C day/night/paddy water temperatures respectively. Sucrose phosphate synthase (SPS) activity was measured at saturating substrate concentrations at 59 days after planting. SPS activity increased 2 and 3 fold with increasing CO{sub 2} at 28 and 34{degree}C air temperatures respectively. At 40{degree}C SPS activity decreased by 37% at elevated CO{sub 2} and most plants failed to reach maturity. Similar responses were found in leaf samples taken in the dark. These results indicate that SPS, an enzyme involved in the regulation of C partitioning in leaves, increases in activity at elevated CO{sub 2}. This is in contrast to previous results with soybean. The changes in SPS activity will also be discussed in relation to leaf starch/sucrose ratios.

  17. Purification, properties and substrate specificity of adenosine triphosphate sulphurylase from spinach leaf tissue

    PubMed Central

    Shaw, W. H.; Anderson, J. W.

    1972-01-01

    1. ATP sulphurylase was purified up to 1000-fold from spinach leaf tissue. Activity was measured by sulphate-dependent [32P]PPi–ATP exchange. The enzyme was separated from Mg2+-requiring alkaline pyrophosphatase (which interferes with the PPi–ATP-exchange assay) and from other PPi–ATP-exchange activities. No ADP sulphurylase activity was detected. 2. Sulphate was the only form of inorganic sulphur that catalysed PPi–ATP exchange; Km (sulphate) was 3.1mm, Km (ATP) was 0.35mm and the pH optimum was 7.5–9.0. The enzyme was insensitive to thiol-group reagents and required either Mg2+ or Co2+ for activity. 3. The enzyme catalysed [32P]PPi–dATP exchange; Km (dATP) was 0.84mm and V (dATP) was 30% of V (ATP). Competition between ATP and dATP was demonstrated. 4. Selenate catalysed [32P]PPi–ATP exchange and competed with sulphate; Km (selenate) was 1.0mm and V (selenate) was 30% of V (sulphate). No AMP was formed with selenate as substrate. Molybdate did not catalyse PPi–ATP exchange, but AMP was formed. 5. Synthesis of adenosine 5?-[35S]sulphatophosphate was demonstrated by coupling purified ATP sulphurylase and Mg2+-dependent alkaline pyrophosphatase (also prepared from spinach) with [35S]sulphate and ATP as substrates; adenosine 5?-sulphatophosphate was not synthesized in the absence of pyrophosphatase. Some parameters of the coupled system are reported. PMID:5073745

  18. Sucrose Phosphate Is Not Transported into Vacuoles or Tonoplast Vesicles from Red Beet (Beta vulgaris) Hypocotyl 1

    PubMed Central

    Echeverria, Ed; Salvucci, Michael E.

    1991-01-01

    Tonoplast vesicles and vacuoles isolated from red beet (Beta vulgaris L.) hypocotyl accumulated externally supplied [14C]sucrose but not [14C]sucrose phosphate despite the occurrence of sucrose phosphate phosphohydrolytic activity in the vacuole. The activities of sucrose synthase and sucrose phosphate synthase in whole cell extracts were 960 and 30 nanomoles per milligram protein per minute, respectively; whereas, no sucrose synthesizing activity was measured in tonoplast preparations. The results obtained in this investigation are incompatible with the involvement of sucrose phosphate synthase in the process of sucrose synthesis and accumulation in the storage cells of red beet. PMID:16668291

  19. The effect of cell age on chloroplast structure and chlorophyll in cultured spinach leaf discs

    Microsoft Academic Search

    D. G. Cran; J. V. Possingham

    1974-01-01

    Summary Discs from young spinach leaves show a 50-fold increase in fresh weight and a 10-fold increase in chlorophyll over 7 days when cultured in high intensity white light (6.5 mWcm?2). In darkness the increase in fresh weight is 10-fold while chlorophyll decreases. Discs from mature spinach leaves show only a 2-fold increase in fresh weight and a marked decrease

  20. Antisense repression of sucrose phosphate synthase in transgenic muskmelon alters plant growth and fruit development

    SciTech Connect

    Tian, Hongmei; Ma, Leyuan; Zhao, Cong; Hao, Hui; Gong, Biao [College of Horticulture Science and Engineering, State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong 271018 (China)] [College of Horticulture Science and Engineering, State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong 271018 (China); Yu, Xiyan, E-mail: yuxiyan@sdau.edu.cn [College of Horticulture Science and Engineering, State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong 271018 (China)] [College of Horticulture Science and Engineering, State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong 271018 (China); Wang, Xiufeng, E-mail: xfwang@sdau.edu.cn [College of Horticulture Science and Engineering, State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong 271018 (China)] [College of Horticulture Science and Engineering, State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong 271018 (China)

    2010-03-12

    To unravel the roles of sucrose phosphate synthase (SPS) in muskmelon (Cucumis melo L.), we reduced its activity in transgenic muskmelon plants by an antisense approach. For this purpose, an 830 bp cDNA fragment of muskmelon sucrose phosphate synthase was expressed in antisense orientation behind the 35S promoter of the cauliflower mosaic virus. The phenotype of the antisense plants clearly differed from that of control plants. The transgenic plant leaves were markedly smaller, and the plant height and stem diameter were obviously shorter and thinner. Transmission electron microscope observation revealed that the membrane degradation of chloroplast happened in transgenic leaves and the numbers of grana and grana lamella in the chloroplast were significantly less, suggesting that the slow growth and weaker phenotype of transgenic plants may be due to the damage of the chloroplast ultrastructure, which in turn results in the decrease of the net photosynthetic rate. The sucrose concentration and levels of sucrose phosphate synthase decreased in transgenic mature fruit, and the fruit size was smaller than the control fruit. Together, our results suggest that sucrose phosphate synthase may play an important role in regulating the muskmelon plant growth and fruit development.

  1. Short-term water stress leads to a stimulation of sucrose synthesis by activating sucrose-phosphate synthase

    Microsoft Academic Search

    Paul Quick; Gabi Siegl; Ekkehard Neuhaus; Regina Feil; Mark Stitt

    1989-01-01

    The aim of this work was to identify which aspects of photosynthetic metabolism respond most sensitively to leaf water deficit. Spinach (Spinacia oleracea L.) leaf discs were floated on sorbitol concentrations of increasing molarity and changes of the protoplast volume were estimated using [14C]sorbitol and 3H2O penetration. Detached leaves were also wilted until 10% of their fresh weight was lost.

  2. The enzymology of adenosine triphosphate sulphurylase from spinach leaf tissue. Kinetic studies and a proposed reaction mechanism

    PubMed Central

    Shaw, W. H.; Anderson, J. W.

    1974-01-01

    1. Sulphate-dependent PPi–ATP exchange, catalysed by purified spinach leaf ATP sulphurylase, was correlated with the concentration of MgATP2? and MgP2O72?; ATP sulphurylase activity was not correlated with the concentration of free Mg2+. 2. Sulphate-dependent PPi–ATP exchange was independent of PPi concentration, but dependent on the concentration of ATP and sulphate. The rate of sulphate-dependent PPi–ATP exchange was quantitatively defined by the rate equation applicable to the initial rate of a bireactant sequential mechanism under steady-state conditions. 3. Chlorate, nitrate and ADP inhibited the exchange reaction. The inhibition by chlorate and nitrate was uncompetitive with respect to ATP and competitive with respect to sulphate. The inhibition by ADP was competitive with respect to ATP and non-competitive with respect to sulphate. 4. ATP sulphurylase catalysed the synthesis of [32P]ATP from [32P]PPi and adenosine 5?-sulphatophosphate in the absence of sulphate; some properties of the reaction are described. Enzyme activity was dependent on the concentration of PPi and adenosine 5?-sulphatophosphate. 5. The synthesis of ATP from PPi and adenosine 5?-sulphatophosphate was inhibited by sulphate and ATP. The inhibition by sulphate was non-competitive with respect to PPi and adenosine 5?-sulphatophosphate; the inhibition by ATP was competitive with respect to adenosine 5?-sulphatophosphate and non-competitive with respect to PPi. It was concluded that the reaction catalysed by spinach leaf ATP sulphurylase was ordered; expressing the order in the forward direction, MgATP2? was the first product to react with the enzyme and MgP2O72? was the first product released. 6. The expected exchange reaction between sulphate and adenosine 5?-sulphatophosphate could not be demonstrated. PMID:4463947

  3. Effect of elevated CO[sub 2] and temperature on sucrose phosphate synthase activity and carbohydrate metabolism in rice

    SciTech Connect

    Hussain, M.W.

    1992-01-01

    The kinetics of sucrose phosphate synthase (SPS) activity were studied in leaf extracts of rice (Oryza sativa L. cv. IR-3-). The SPS activity showed hyperbolic and sigmoidal response, respectively, as a function of concentration for its two substrates, UDPG and F6P. The K[sub m] (UDPG) and S[sub 0.5] (F6P) were 2.7 and 2 mM, respectively. The enzyme was activated in an allosteric manner by G6P at low F6P concentrations, while P[sub i] inhibited it. Diel profiles indicated SPS was light activated and the activation was greatest under limiting assay conditions. Leaves were pretreated either with mannose to sequester endogenous P[sub i] or with exogenous P[sub i]. Mannose pretreatment made the enzyme relatively insensitive to p[sub i] inhibition, whereas P[sub i] pretreatment enhanced the inhibitory effect. These data suggest that the rice SPS enzyme exists in two states, a light-active, P[sub i]-insensitive form, and a dark form that is more P[sub i]-sensitive. Based on these kinetic analysis, leaf SPS activity was examined as a function of CO[sub 2]-enrichment and growth temperature for rice plants grown under natural irradiance at 330 and 660 [mu]L CO[sub 2] L[sup [minus]1] and growth temperatures ranging from 25 to 37[degrees]C. CO[sub 2]-enrichment at 28[degrees]C caused a season-long increase (18%) in SPS activity measured under limiting or saturating assay conditions. It is also increased the leaf starch and sucrose content, but lowered the total nitrogen. Sucrose content was higher than starch, suggesting rice is a sucrose and starch storer. In CO[sub 2]-enriched plants, SPS activity increased with growth temperature up to 34[degrees]C, but declined at 38[degrees]C. The increasing temperature caused a significant linear decrease in starch content, whereas sucrose was only slightly decreased, while fructose was increased. The data suggest that up-regulation of SPS activity is an acclimation response of rice to elevated CO[sub 2] and temperature.

  4. Purification and characterization of a novel NADPH(NADH)-dependent hydroxypyruvate reductase from spinach leaves. Comparison of immunological properties of leaf hydroxypyruvate reductases.

    PubMed Central

    Kleczkowski, L A; Randall, D D

    1988-01-01

    A novel hydroxypyruvate reductase preferring NADPH to NADH as a cofactor was purified over 1500-fold from spinach leaf extracts. The enzyme was an oligomer of about 70 kDa, composed of two subunits of 38 kDa each. The Km for hydroxypyruvate (with NADPH) was about 0.8 mM in the pH range 5.5-6.5, and 0.3 mM at pH 8.2. The Vmax. was highest in the pH range 5.5-6.5 and decreased by about 65% at pH 8.2. Above pH 6.0, the enzyme was prone to a strong substrate inhibition by hydroxypyruvate. The reductase could use glyoxylate as an alternative substrate, with rates up to one-quarter of those with hydroxypyruvate. This glyoxylate-dependent activity preferred NADPH to NADH as a cofactor. Rabbit antibodies prepared against NADPH(NADH)-hydroxypyruvate reductase were highly specific for this enzyme and did not cross-react with peroxisomal NADH(NADPH)-dependent hydroxypyruvate reductase, as found by Western immunoblots of proteins from leaf extracts of spinach, pea and wheat. Antibodies raised against purified NADH(NADPH)-hydroxypyruvate reductase were also highly specific, recognizing only their own antigen. To our knowledge, this is the first report in the literature of the occurrence of NADPH(NADH)-hydroxypyruvate reductase in leaves, and the first to provide immunological comparison of leaf hydroxypyruvate reductases. Because of the relatively high rates of the novel reductase in leaf extracts (at least 20 mumol/h per mg of chlorophyll), this enzyme might be an important side-component of the glycollate pathway (photorespiration), possibly utilizing hydroxypyruvate 'leaked' from peroxisomes, and thus contributing to the glycerate pool derived from glycollate. Because of the glyoxylate-dependent activity, the enzyme may also contribute to glycollate formation in leaves. Images Fig. 1. Fig. 5. Fig. 6. PMID:3281657

  5. Diel activity of sucrose phosphate synthase in rice. [Oryza sativa L

    SciTech Connect

    Hussain, M.W.; Bowes, G.; Rowland-Bamford, A.J.; Allen, L.H. (Univ. of Florida, Gainesville (United States))

    1991-05-01

    Rice (Oryza sativa L.) was grown in growth chambers at 28/23C day/night temperatures with 16-h photoperiod at 600 umol m{sup {minus}2} s{sup {minus}1}. Diel sucrose phosphate synthase (SPS) activity, at 21 days after planting, was measured at saturating substrate concentrations. Data suggests that SPS activity increased during illumination to a maximum of 0.8 nmol mg{sup {minus}1} protein min{sup {minus}1} after 5h. Throughout the remainder of the light period there was a slow decline in activity. Upon darkening, activity further declined to 0.4 nmol mg{sup {minus}1} protein min{sup {minus}1}, a basal level that was maintained throughout the night. It appears that rice SPS undergoes light/dark transitions, suggesting there may be two kinetic forms of SPS. Changes in SPS activity will be discussed in relation to kinetic studies, and also CO{sub 2} enrichment of rice during growth.

  6. Differences in the metabolite profiles of spinach (Spinacia oleracea L.) leaf in different concentrations of nitrate in the culture solution.

    PubMed

    Okazaki, Keiki; Oka, Norikuni; Shinano, Takuro; Osaki, Mitsuru; Takebe, Masako

    2008-02-01

    The nitrogen (N) status of a plant determines the composition of its major components (amino acids, proteins, carbohydrates and organic acids) and, directly or indirectly, affects the quality of agricultural products in terms of their calorific value and taste. Although these effects are guided by changes in metabolic pathways, no overall metabolic analysis has previously been conducted to demonstrate such effects. Here, metabolite profiling using gas chromatography-mass spectrometry (GC-MS) was used to evaluate the effect of N levels on spinach tissue, comparing two cultivars that differed in their ability to use N. Wide variation in N content was observed without any distinct inhibition of growth in either cultivar. Principal component analysis (PCA) and self-organizing mapping (SOM) were undertaken to describe changes in the metabolites of mature spinach leaves. In PCA, the first component accounted for 44.5% of the total variance, the scores of which was positively correlated with the plant's N content, and a close relationship between metabolite profiles and N status was observed. Both PCA and SOM revealed that metabolites could be broadly divided into two types, correlating either positively or negatively with plant N content. The simple and co-coordinated metabolic stream, containing both general and spinach-specific aspects of plant N content, will be useful in future research on such topics as the detection of environmental effects on spinach through comprehensive metabolic profiling. PMID:18089581

  7. Characterization of interactions between Escherichia coli O157:H7 with epiphytic bacteria in vitro and on spinach leaf surfaces

    E-print Network

    Falkinham, Joseph

    Characterization of interactions between Escherichia coli O157:H7 with epiphytic bacteria in vitro coli O157:H7 and spinach phylloepi- phytic bacteria and identified those that influence persistence of E. coli O157:H7 on edible plants. A total of 1512 phylloepiphytic bacterial isolates were screened

  8. Chilling Delays Circadian Pattern of Sucrose Phosphate Synthase and Nitrate Reductase Activity in Tomato1

    PubMed Central

    Jones, Tamara L.; Tucker, Dawn E.; Ort, Donald R.

    1998-01-01

    Overnight low-temperature exposure inhibits photosynthesis in chilling-sensitive species such as tomato (Lycopersicon esculentum) and cucumber by as much as 60%. In an earlier study we showed that one intriguing effect of low temperature on chilling-sensitive plants is to stall the endogenous rhythm controlling transcription of certain nuclear-encoded genes, causing the synthesis of the corresponding transcripts and proteins to be mistimed when the plant is rewarmed. Here we show that the circadian rhythm controlling the activity of sucrose phosphate synthase (SPS) and nitrate reductase (NR), key control points of carbon and nitrogen metabolism in plant cells, is delayed in tomato by chilling treatments. Using specific protein kinase and phosphatase inhibitors, we further demonstrate that the chilling-induced delay in the circadian control of SPS and NR activity is associated with the activity of critical protein phosphatases. The sensitivity of the pattern of SPS activity to specific inhibitors of transcription and translation indicates that there is a chilling-induced delay in SPS phosphorylation status that is caused by an effect of low temperature on the expression of a gene coding for a phosphoprotein phosphatase, perhaps the SPS phosphatase. In contrast, the chilling-induced delay in NR activity does not appear to arise from effects on NR phosphorylation status, but rather from direct effects on NR expression. It is likely that the mistiming in the regulation of SPS and NR, and perhaps other key metabolic enzymes under circadian regulation, underlies the chilling sensitivity of photosynthesis in these plant species. PMID:9733534

  9. A high-performance liquid chromatography-based radiometric assay for sucrose-phosphate synthase and other UDP-glucose requiring enzymes

    SciTech Connect

    Salvucci, M.E.; Crafts-Brandner, S.J. (University of Kentucky, Lexington (USA))

    1991-05-01

    A method for product analysis that eliminates a problematic step in the radiometric sucrose-phosphate synthase assay is described. The method uses chromatography on a boronate-derivatized high-performance liquid chromatography column to separate the labeled product, (14C)sucrose phosphate, from unreacted uridine 5{prime}-diphosphate-(14C)glucose (UDP-Glc). Direct separation of these compounds eliminates the need for treatment of the reaction mixtures with alkaline phosphatase, thereby avoiding the problem of high background caused by contaminating phosphodiesterase activity in alkaline phosphatase preparations. The method presented in this paper can be applied to many UDP-Glc requiring enzymes; here the authors show its use for determining the activities of sucrose-phosphate synthase, sucrose synthase, and uridine diphosphate-glucose pyrophosphorylase in plant extracts.

  10. Extraction and characterization of mixed phase KNO2-KNO3 nanocrystals derived from flat-leaf green spinach

    NASA Astrophysics Data System (ADS)

    Hazarika, S.; Mohanta, D.

    2013-01-01

    Naturally available green spinach, which is a rich source of potassium, was used as the key ingredient to extract mixed-phase ferroelectric crystals of nitrite and nitrate derivatives (KNO2 + KNO3). The KNO3 phase was found to be dominant for higher pH values, as revealed by the x-ray diffraction patterns. The characteristic optical absorption spectra exhibited intra-band ?-?* electronic transitions, whereas Fourier transform infrared spectra exhibited characteristic N-O stretching vibrations. Differential scanning calorimetry revealed a broad endothermic peak at ˜121.8 °C, highlighting a transition from phase II to I via phase III of KNO3. Obtaining nanoscale ferroelectrics via the adoption of green synthesis is economically viable for large-scale production and possible application in ferroelectric elements/devices.

  11. Activities of starch hydrolytic enzymes and sucrose-phosphate synthase in the stems of rice subjected to water stress during grain filling.

    PubMed

    Yang, J; Zhang, J; Wang, Z; Zhu, Q

    2001-11-01

    To understand the effect of water stress on the remobilization of prestored carbon reserves, the changes in the activities of starch hydrolytic enzymes and sucrose-phosphate synthase (SPS) in the stems of rice (Oryza sativa L.) during grain filling were investigated. Two rice cultivars, showing high lodging-resistance and slow remobilization, were grown in the field and subjected to well-watered (WW, psi(soil)=0) and water-stressed (WS, psi(soil)=-0.05 MPa) treatments 9 d after anthesis (DAA) till maturity. Leaf water potentials of both cultivars markedly decreased during the day as a result of WS treatment, but completely recovered by early morning. WS treatment accelerated the reduction of starch in the stems, promoted the reallocation of prefixed (14)C from the stems to grains, shortened the grain filling period, and increased the grain filling rate. More soluble sugars including sucrose were accumulated in the stems under WS than under WW treatments. Both alpha- and beta-amylase activities were enhanced by the WS, with the former enhanced more than the latter, and were significantly correlated with the concentrations of soluble sugars in the stems. The other two possible starch-breaking enzymes, alpha-glucosidase and starch phosphorylase, showed no significant differences in the activities between the WW and WS treatments. Water stress also increased the SPS activity that is responsible for sucrose production. Both V(limit) and V(max), the activities of the enzyme at limiting and saturating substrate concentrations, were enhanced and the activation state (V(limit)/V(max)) was also increased as a result of the more significant enhancement of V(limit). The enhanced SPS activity was closely correlated with an increase of sucrose accumulation in the stems. The results suggest that the fast hydrolysis of starch and increased carbon remobilization were attributed to the enhanced alpha-amylase activity and the high activation state of SPS when the rice was subjected to water stress. PMID:11604456

  12. Effect of Light on the Chloroplast Division Cycle and DNA Synthesis in Cultured Leaf Discs of Spinach

    PubMed Central

    Hashimoto, Haruki; Possingham, John Victor

    1989-01-01

    The effects of light on both the division cycle of chloroplasts and the synthesis of chloroplast DNA were investigated in cultured discs taken from the distal end of 2-centimeter spinach (Spinacia oleracea) leaves. Comparisons were made of discs cultured for a maximum of 4 days in a shaking liquid medium under continuous white light, darkness, and of discs cultured for 1 day in light following 3 days in darkness. In continuous white light the shortest generation time of chloroplasts observed in this study was 19.4 hours and the duration of spherical, ovoid, and dumbbell-shaped stages in the division cycle were 13.4, 2.8, and 3.1 hours, respectively. In darkness the generation times of chloroplasts extended to 51.5 hours. Under these conditions the duration of spherical, ovoid, and dumbbell-shaped stages were 22.8, 8.4, and 20.2 hours, respectively, suggesting that in darkness the separation of dumbbell-shaped chloroplasts may be the rate limiting step. When discs cultured in the dark were transferred to light, most dumbbell-shaped chloroplasts separated into daughter chloroplasts in less than an hour. Measurements of chloroplast DNA established that the cellular level of chloroplast DNA increased 10-fold over the 4 days of culture in continuous white light. Comparisons of the plastids of dark and light grown discs showed that the synthesis of chloroplast DNA was enhanced by light. Observations of DAPI stained dividing chloroplasts indicate that DNA partitioning can take place during the final stage of chloroplast division and that it does not precede plastid division. Images Figure 2 PMID:16666681

  13. The Structure of Sucrose Phosphate Synthase from Halothermothrix orenii Reveals Its Mechanism of Action and Binding Mode[W][OA

    PubMed Central

    Chua, Teck Khiang; Bujnicki, Janusz M.; Tan, Tien-Chye; Huynh, Frederick; Patel, Bharat K.; Sivaraman, J.

    2008-01-01

    Sucrose phosphate synthase (SPS) catalyzes the transfer of a glycosyl group from an activated donor sugar, such as uridine diphosphate glucose (UDP-Glc), to a saccharide acceptor d-fructose 6-phosphate (F6P), resulting in the formation of UDP and d-sucrose-6?-phosphate (S6P). This is a central regulatory process in the production of sucrose in plants, cyanobacteria, and proteobacteria. Here, we report the crystal structure of SPS from the nonphotosynthetic bacterium Halothermothrix orenii and its complexes with the substrate F6P and the product S6P. SPS has two distinct Rossmann-fold domains with a large substrate binding cleft at the interdomain interface. Structures of two complexes show that both the substrate F6P and the product S6P bind to the A-domain of SPS. Based on comparative analysis of the SPS structure with other related enzymes, the donor substrate, nucleotide diphosphate glucose, binds to the B-domain of SPS. Furthermore, we propose a mechanism of catalysis by H. orenii SPS. Our findings indicate that SPS from H. orenii may represent a valid model for the catalytic domain of plant SPSs and thus may provide useful insight into the reaction mechanism of the plant enzyme. PMID:18424616

  14. Mild water stress of Phaseolus vulgaris plants leads to reduced starch synthesis and extractable sucrose phosphate synthase activity

    SciTech Connect

    Vassey, T.L.; Sharkey, T.D. (Univ. of Wisconsin, Madison (USA))

    1989-04-01

    Mild water stress, on the order of {minus}1.0 megapascals xylem water potential, can reduce the rate of photosynthesis and eliminate the inhibition of photosynthesis caused by O{sub 2} in water-stress-sensitive plants such as Phaseolus vulgaris. To investigate the lack of O{sub 2} inhibition of photosynthesis, we measured stromal and cytosolic fructose-1,6-bisphosphatase, sucrose phosphate synthase, and partitioning of newly fixed carbon between starch and sucrose before, during, and after mild water stress. The extractable activity of the fructose bisphosphatases was unaffected by mild water stress. The extractable activity of SPS was inhibited by more than 60% in plants stressed to water potentials of {minus}0.9 megapascals. Water stress caused a decline in the starch/sucrose partitioning ratio indicating that starch synthesis was inhibited more than sucrose synthesis. We conclude that the reduced rate of photosynthesis during water stress is caused by stomatal closure, and that the restriction of CO{sub 2} supply caused by stomatal closure leads to a reduction in the capacity for both starch and sucrose synthesis. This causes the reduced O{sub 2} inhibition and abrupt CO{sub 2} saturation of photosynthesis.

  15. Intracellular localization of phosphorylases in spinach and pea leaves

    Microsoft Academic Search

    Martin Steup; Erwin Latzko

    1979-01-01

    Starch phosphorylase activity in extracts of spinach or pea leaves and of isolated chloroplasts was determined and separated by electrophoresis in polyacrylamide gels. In spinach leaf extracts, a specific activity of 16 nmol glucose 1-phosphate formed per min per mg protein was found, whereas a lower value (6 nmol per min per mg protein) was observed in preparations of isolated

  16. Layered Spinach Salad Ingredients

    E-print Network

    Liskiewicz, Maciej

    Layered Spinach Salad Ingredients: 1 pound spinach leaves, torn 8 ounces mushrooms, whole 1 onion 2 dill weed 1 1/2 teaspoons lemon pepper 1 teaspoon onion powder Directions 1. Tear spinach into bite. Layer in bowl. 3. Cut the ends off of the onion, and peel off the brown layers. Run under water

  17. Sucrose Phosphate Synthase, Sucrose Synthase, and Invertase Activities in Developing Fruit of Lycopersicon esculentum Mill. and the Sucrose Accumulating Lycopersicon hirsutum Humb. and Bonpl. 1

    PubMed Central

    Miron, Daphne; Schaffer, Arthur A.

    1991-01-01

    The green-fruited Lycopersicon hirsutum Humb. and Bonpl. accumulated sucrose to concentrations of about 118 micromoles per gram fresh weight during the final stages of development. In comparison, Lycopersicon esculentum Mill. cultivars contained less than 15 micromoles per gram fresh weight of sucrose at the ripe stage. Glucose and fructose levels remained relatively constant throughout development in L. hirsutum at 22 to 50 micromoles per gram fresh weight each. Starch content was low even at early stages of development, and declined further with development. Soluble acid invertase (EC 3.2. 1.26) activity declined concomitant with the rise in sucrose content. Acid invertase activity, which was solubilized in 1 molar NaCl (presumably cell-wall bound), remained constant throughout development (about 3 micromoles of reducing sugars (per gram fresh weight) per hour. Sucrose phosphate synthase (EC 2.4.1.14) activity was present at about 5 micromoles of sucrose (per gram fresh weight) per hour even at early stages of development, and increased sharply to about 40 micromoles of sucrose (per gram fresh weight) per hour at the final stages of development studied, parallel to the rise in sucrose content. In comparison, sucrose phosphate synthase activity in L. esculentum remained low throughout development. The possible roles of the sucrose metabolizing enzymes in determining sucrose accumulation are discussed. PMID:16668028

  18. Texas Crop Profile: Spinach

    E-print Network

    Hall, Kent D.; Holloway, Rodney L.; Smith, Dudley

    2000-04-12

    - gots, cucumber beetles, a variety of foliage feeders and several soil insects. Aphids Frequency of occurrence: In Texas, aphids are an occasional pest of spinach in 1 out of 4 years and will be a problem throughout the growing sea- son. Much..., applying insecticides and planting alternative host plants near spinach fields can help reduce aphid levels. Biological control practices: Parasitic wasps, syrphid flies and lady beetles are effective aphid parasites and predators. However, immature bene...

  19. Expression Patterns, Activities and Carbohydrate-Metabolizing Regulation of Sucrose Phosphate Synthase, Sucrose Synthase and Neutral Invertase in Pineapple Fruit during Development and Ripening

    PubMed Central

    Zhang, Xiu-Mei; Wang, Wei; Du, Li-Qing; Xie, Jiang-Hui; Yao, Yan-Li; Sun, Guang-Ming

    2012-01-01

    Differences in carbohydrate contents and metabolizing-enzyme activities were monitored in apical, medial, basal and core sections of pineapple (Ananas comosus cv. Comte de paris) during fruit development and ripening. Fructose and glucose of various sections in nearly equal amounts were the predominant sugars in the fruitlets, and had obvious differences until the fruit matured. The large rise of sucrose/hexose was accompanied by dramatic changes in sucrose phosphate synthase (SPS) and sucrose synthase (SuSy) activities. By contrast, neutral invertase (NI) activity may provide a mechanism to increase fruit sink strength by increasing hexose concentrations. Furthermore, two cDNAs of Ac-sps (accession no. GQ996582) and Ac-ni (accession no. GQ996581) were first isolated from pineapple fruits utilizing conserved amino-acid sequences. Homology alignment reveals that the amino acid sequences contain some conserved function domains. Transcription expression analysis of Ac-sps, Ac-susy and Ac-ni also indicated distinct patterns related to sugar accumulation and composition of pineapple fruits. It suggests that differential expressions of multiple gene families are necessary for sugar metabolism in various parts and developmental stages of pineapple fruit. A cycle of sucrose breakdown in the cytosol of sink tissues could be mediated through both Ac-SuSy and Ac-NI, and Ac-NI could be involved in regulating crucial steps by generating sugar signals to the cells in a temporally and spatially restricted fashion. PMID:22949808

  20. Analysis of gene-disruption mutants of a sucrose phosphate synthase gene in rice, OsSPS1, shows the importance of sucrose synthesis in pollen germination.

    PubMed

    Hirose, Tatsuro; Hashida, Yoichi; Aoki, Naohiro; Okamura, Masaki; Yonekura, Madoka; Ohto, Chikara; Terao, Tomio; Ohsugi, Ryu

    2014-08-01

    The molecular function of an isoform of sucrose phosphate synthase (SPS) in rice, OsSPS1, was investigated using gene-disruption mutant lines generated by retrotransposon insertion. The progeny of the heterozygote of disrupted OsSPS1 (SPS1(+/-)) segregated into SPS1(+/+), SPS1(+/-), and SPS1(-/-) at a ratio of 1:1:0. This distorted segregation ratio, together with the expression of OsSPS1 in the developing pollen revealed by quantitative RT-PCR analysis and promoter-beta-glucuronidase (GUS) fusion assay, suggested that the disruption of OsSPS1 results in sterile pollen. This hypothesis was reinforced by reciprocal crosses of SPS1(+/-) plants with wild-type plants in which the disrupted OsSPS1 was not paternally transmitted to the progeny. While the pollen grains of SPS(+/-) plants normally accumulated starch during their development, pollen germination on the artificial media was reduced to half of that observed in the wild-type control. Overall, our data suggests that sucrose synthesis via OsSPS1 is essential in pollen germination in rice. PMID:25017165

  1. Nodule-enhanced expression of a sucrose phosphate synthase gene member ( MsSPSA ) has a role in carbon and nitrogen metabolism in the nodules of alfalfa ( Medicago sativa L.)

    Microsoft Academic Search

    Lorenzo Aleman; Jose Luis Ortega; Martha Martinez-Grimes; Mark Seger; Francisco Omar Holguin; Diana J. Uribe; David Garcia-Ibilcieta; Champa Sengupta-Gopalan

    2010-01-01

    Sucrose phosphate synthase (SPS) catalyzes the first step in the synthesis of sucrose in photosynthetic tissues. We characterized\\u000a the expression of three different isoforms of SPS belonging to two different SPS gene families in alfalfa (Medicago sativa L.), a previously identified SPS (MsSPSA) and two novel isoforms belonging to class B (MsSPSB and MsSPSB3). While MsSPSA\\u000a showed nodule-enhanced expression, both

  2. Extractable activities and protein content of sucrose-phosphate synthase, sucrose synthase and neutral invertase in trunk tissues of Robinia pseudoacacia L. are related to cambial wood production and heartwood formation

    Microsoft Academic Search

    Siegfried Hauch; Elisabeth Magel

    1998-01-01

    .   The presence of sucrose synthesizing and degrading enzymes and the correlation of their enzyme activity with cambial growth\\u000a and heartwood formation are demonstrated in trunks of Robinia pseudoacacia L., black locust. Sucrose is formed by sucrose-phosphate synthase (SPS; EC 2.4.1.14), predominantly in the storage part of\\u000a the sapwood. In the cambial differentiation zone and the sapwood-heartwood transition zone, both

  3. Differential transcriptional regulation of banana sucrose phosphate synthase gene in response to ethylene, auxin, wounding, low temperature and different photoperiods during fruit ripening and functional analysis of banana SPS gene promoter

    Microsoft Academic Search

    Swarup Roy Choudhury; Sujit Roy; Ranjan Das; Dibyendu N. Sengupta

    2008-01-01

    Sucrose phosphate synthase (SPS) (EC 2.3.1.14) is the key regulatory component in sucrose formation in banana (Musa acuminata subgroup Cavendish, cv Giant governor) fruit during ripening. This report illustrates differential transcriptional responses of banana SPS gene following ethylene, auxin, wounding, low temperature and different photoperiods during ripening in banana fruit. Whereas\\u000a ethylene strongly stimulated SPS transcript accumulation, auxin and cold

  4. LEAFMINER RESISTANCE IN SPINACH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leafminer (Liriomyza spp.) is a major insect pest of many important vegetable crops including spinach (Spinacia oleracea). Chemical control is not long lasting, and it is well documented that leafminers can develop a high degree of resistance to insecticides. Resistant varieties remain the most econ...

  5. Texas Crop Profile: Spinach 

    E-print Network

    Hall, Kent D.; Holloway, Rodney L.; Smith, Dudley

    2000-04-12

    for crown maggots. Biological control practices: Fire ants can help reduce crown maggot numbers but fire ants are affected by chemical applications directed at other pests. Postharvest control practices: There are none. Cucumber Beetles Frequency... production areas are the Lower Rio Grande Valley (McAllen- Harlingen) and the Plains area surrounding Lubbock. Cultural Practices Spinach grows well under cool, dry conditions. Fresh market varieties such as Samish, Fall Green and Coho are direct seeded...

  6. Evidence for the Glutamine Synthetase\\/Glutamate Synthase Pathway during the Photorespiratory Nitrogen Cycle in Spinach Leaves

    Microsoft Academic Search

    K. C. Woo; J. F. Morot-Gaudry; R. E. Summons; C. B. Osmond

    1982-01-01

    Spinach leaf (Spiucia okracea L.)discs infiltrated with(1Niglycine wereincubated at25°Cinthelight andindarkness for0,30,60and90 minutes. Thekinetics of'5N-incorporation intoglutamine, glutamate, asparagine, aspartate, andserine from(1\\

  7. The role of tryptophan in the ferredoxin-dependent nitrite reductase of spinach

    Microsoft Academic Search

    Jatindra N. Tripathy; Masakazu Hirasawa; Sung-Kun Kim; Aaron T. Setterdahl; James P. Allen; David B. Knaff

    2007-01-01

    A system has been developed for expressing a His-tagged form of the ferredoxin-dependent nitrite reductase of spinach in Escherichia coli. The catalytic and spectral properties of the His-tagged, recombinant enzyme are similar, but not identical, to those previously\\u000a observed for nitrite reductase isolated directly from spinach leaf. A detailed comparison of the spectral, catalytic and fluorescence\\u000a properties of nitrite reductase

  8. Modulation of carbohydrate metabolism and chloroplast structure in sugarcane leaves which were infected by Sugarcane Yellow Leaf Virus (SCYLV)

    Microsoft Academic Search

    S.-L. Yan; A. T. Lehrer; M. R. Hajirezaei; A. Springer; E. Komor

    2008-01-01

    Non-symptomatic sugarcane plants infected with Sugarcane Yellow Leaf Virus showed starch in mesophyll and bundle sheath cells. In situ-hybridization of mRNAs of sucrose-phosphate phosphatase and ADP-glucose pyrophosphorylase revealed that infected leaves contained SPPase and AGPase in mesophyll cells, Kranz cells and bundle sheath cells. In contrast virus-free leaves contained SPPase only in Kranz cells and AGPase only in bundle sheath

  9. Spinach and Mushroom Enchilada Lasagna Ingredients

    E-print Network

    Liskiewicz, Maciej

    in half 1/2 teaspoon oregano 20 ounces spinach, frozen, 2 packages, thawed 2 cups reduced fat Monterey minutes. When mushrooms are soft, add oregano and spinach and heat through. 6. Pour half of the enchilada

  10. The effect of cerium (III) on the chlorophyll formation in spinach.

    PubMed

    Fashui, Hong; Ling, Wang; Xiangxuan, Meng; Zheng, Wei; Guiwen, Zhao

    2002-12-01

    The effect of Ce(3+) on the chlorophyll (chl) of spinach was studied in pot culture experiments. The results showed that Ce(3+) could obviously stimulate the growth of spinach and increase its chlorophyll contents and photosynthetic rate. It could also improve the PSII formation and enhance its electron transport rate of PSII as well. By inductively coupled plasma-mass spectroscopy and atom absorption spectroscopy methods, it was revealed that the rare-earth-element (REE) distribution pattern in the Ce(3+)-treated spinach was leaf > root > shoot in Ce(3+) contents. The spinach leaves easily absorbed REEs. The Ce(3+) contents of chloroplast and chlorophyll of the Ce(3+)-treated spinach were higher than that of any other rare earth and were much higher than that of the control; it was also suggested that Ce(3+) could enter the chloroplast and bind easily to chlorophyll and might replace magnesium to form Ce-chlorophyll. By ultraviolet-visible, Fourier transform infrared, and extended X-ray absorption fine structure (EXAFS) methods, Ce(3+)-coordinated nitrogen of porphyrin rings with eight coordination numbers and average length of the Ce-N bond of 0.251 nm. PMID:12462749

  11. Comparison of Survival of Campylobacter jejuni in the Phyllosphere with That in the Rhizosphere of Spinach and Radish Plants

    PubMed Central

    Brandl, Maria T.; Haxo, Aileen F.; Bates, Anna H.; Mandrell, Robert E.

    2004-01-01

    Campylobacter jejuni has been isolated previously from market produce and has caused gastroenteritis outbreaks linked to produce. We have tested the ability of this human pathogen to utilize organic compounds that are present in leaf and root exudates and to survive in the plant environment under various conditions. Carbon utilization profiles revealed that C. jejuni can utilize many organic acids and amino acids available on leaves and roots. Despite the presence of suitable substrates in the phyllosphere and the rhizosphere, C. jejuni was unable to grow on lettuce and spinach leaves and on spinach and radish roots of plants incubated at 33°C, a temperature that is conducive to its growth in vitro. However, C. jejuni was cultured from radish roots and from the spinach rhizosphere for at least 23 and 28 days, respectively, at 10°C. This enteric pathogen also persisted in the rhizosphere of spinach for prolonged periods of time at 16°C, a temperature at which many cool-season crops are grown. The decline rate constants of C. jejuni populations in the spinach and radish rhizosphere were 10- and 6-fold lower, respectively, than on healthy spinach leaves at 10°C. The enhanced survival of C. jejuni in soil and in the rhizosphere may be a significant factor in its contamination cycle in the environment and may be associated with the sporadic C. jejuni incidence and campylobacteriosis outbreaks linked to produce. PMID:14766604

  12. Functional metagenomics of Escherichia coli O157:H7 interactions with spinach indigenous microorganisms during biofilm formation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The increase in foodborne outbreaks worldwide attributed to fresh fruit and vegetables suggests that produce may serve as an ecological niche for enteric pathogens. Here we examined the interaction of E. coli O157:H7 (EcO157) with spinach leaf microflora during co-colonization and establishment of a...

  13. Evaluation of antioxidant activities of principal carotenoids available in water spinach ( Ipomoea aquatica)

    Microsoft Academic Search

    Hongfei Fu; Bijun Xie; Shaojun Ma; Xinrong Zhu; Gang Fan; Siyi Pan

    2011-01-01

    A fundamental study of free radical-scavenging activity of three carotenoids purified from water spinach (Ipomoea aquatica cv. Slim leaf) by thin layer chromatography and identified by high performance liquid chromatography–mass spectroscopy (HPLC–MS), namely violaxanthin, lutein and ?-carotene, was carried out by measuring the ability to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and 2,2-azobis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radicals and by measuring their ability to

  14. The complete sequence of the genomic RNAs of spinach latent virus

    Microsoft Academic Search

    X. Ge; S. W. Scott; M. T. Zimmerman

    1997-01-01

    Summary.  ?We describe the sequence for the complete genome of spinach latent virus (SpLV). Comparisons of this genome with that of\\u000a the only other complete genome described for a species within the genus Ilarvirus (citrus leaf rugose virus – CiLRV) indicate that while there are marked differences between the RNA 3 of the two viruses,\\u000a their respective RNAs 1 and 2

  15. Persistence of poultry associated Salmonella spp. on spinach plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Pre-harvest spinach contamination can occur via irrigation water and can influence the persistence of Salmonella on spinach leaves. Salmonella persistence on spinach plants should be evaluated as nearby poultry farms can be a critical source of contaminated water run-off. Purpose: The...

  16. THREE NEW RACES OF THE SPINACH DOWNY MILDEW PATHOGEN IDENTIFIED BY A MODIFIED SET OF SPINACH DIFFERENTIALS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spinach downy mildew, caused by Peronospora farinosa f. sp. spinaciae, is the most economically important disease of spinach worldwide. In the past few years, field observations in both the United States and the European Union indicated that spinach cultivars resistant to the seven previously descr...

  17. Effects of plant maturity and bacterial inoculum level on the colonization and internalization of escherichia coli 0157:H7 in growing spinach leaves.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The incidence of foodborne outbreaks linked to fresh produce has increased in the United States. Particularly noteworthy, was the 2006 Escherichia coli O157:H7 outbreak associated with pre-packaged baby spinach. The study aimed to determine whether E. coli O157:H7 would be present in the aerial leaf...

  18. Relative Efficacy of Sodium Hypochlorite Wash Versus Irradiation to Inactivate Escherichia coli O157:H7 Internalized in Leaves of Romaine Lettuce and Baby Spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pathogenic bacteria which are internalized in leaf tissues are protected from the antimicrobial effects of surface treatments. Ionizing radiation is known to penetrate foods, but the efficacy of the process against internalized bacteria is unknown. Leaves of romaine lettuce and baby spinach were cut...

  19. Functional Metagenomics of Escherichia coli O157:H7 Interactions with Spinach Indigenous Microorganisms during Biofilm Formation

    PubMed Central

    Carter, Michelle Q.; Xue, Kai; Brandl, Maria T.; Liu, Feifei; Wu, Liyou; Louie, Jacqueline W.; Mandrell, Robert E.; Zhou, Jizhong

    2012-01-01

    The increase in foodborne outbreaks worldwide attributed to fresh fruit and vegetables suggests that produce may serve as an ecological niche for enteric pathogens. Here we examined the interaction of E. coli O157:H7 (EcO157) with spinach leaf indigenous microorganisms during co-colonization and establishment of a mixed biofilm on a stainless steel surface. Stainless steel surface was selected to mimic the surface of produce-processing equipment, where retention of foodborne pathogens such as EcO157 could serve as a potential source for transmission. We observed a positive effect of spinach-associated microbes on the initial attachment of EcO157, but an antagonistic effect on the EcO157 population at the later stage of biofilm formation. Metagenomic analyses of the biofilm community with the GeoChip revealed an extremely diverse community (gene richness, 23409; Shannon-Weiner index H, 9.55). Presence of EcO157 in the mixed biofilm resulted in a significant decrease in the community ?-diversity (t test, P<0.05), indicating a putative competition between the pathogen and indigenous spinach microbes. The decrease in the ?-diversity of the EcO157-inoculated biofilm at 48 h (ANOVA, P<0.05) suggested a convergent shift in functional composition in response to EcO157 invasion. The success of EcO157 in the mixed biofilm is likely associated with its metabolic potential in utilizing spinach nutrients: the generation time of EcO157 in spinach lysates at 28°C is ? 38 min, which is comparable to that in rich broth. The significant decrease in the abundance of many genes involved in carbon, nitrogen, and phosphorus cycling in the EcO157-inoculated biofilms (t test, P<0.05) further support our conclusion that competition for essential macronutrients is likely the primary interaction between the EcO157 and indigenous spinach-biofilm species. PMID:22957052

  20. Development of an antimicrobial sachet containing encapsulated allyl isothiocyanate to inactivate Escherichia coli O157:H7 on spinach leaves.

    PubMed

    Seo, Hyun-Sun; Bang, Jihyun; Kim, Hoikyung; Beuchat, Larry R; Cho, Seung Yong; Ryu, Jee-Hoon

    2012-10-01

    A sachet releasing allyl isothiocyanate (AIT) vapor was developed and its effectiveness as an antimicrobial packaging system for fresh spinach was evaluated. AIT was encapsulated in calcium alginate beads (AIT beads) and the release of AIT as affected by temperature and relative humidity (RH) was determined. The release rate of AIT from beads increased with increased temperature, but was not significantly affected by RH. A low-density polyethylene (LDPE) sachet containing AIT beads (AIT sachet) was prepared and the rate of release of AIT as affected by film thickness and temperature was studied. The release of AIT from sachets increased significantly with decreased LDPE thickness and increased temperature. Finally, antimicrobial effects of the AIT sachet against Escherichia coli O157:H7 and molds and yeasts (MY) on fresh spinach leaves were determined. E. coli O157:H7 and MY had similar sensitivities to AIT vapor. The number of E. coli O157:H7 on spinach leaves (5.6logCFU/leaf) decreased by 1.6-2.6logCFU/leaf at 4°C and 2.1-5.7logCFU/leaf at 25°C within 5days. The reduction of E. coli O157:H7 was significantly greater at 85% RH than at 43% RH. Reductions on control leaves (no AIT sachet) did not exceed 1.2logCFU/leaf under any of the test conditions. Results of the study will be useful when developing antimicrobial packaging systems to increase the microbiological safety and extend the shelf life of spinach and possibly other fresh produces. PMID:23072699

  1. Proximate composition and mineral content of two edible species of Cnidoscolus (tree spinach).

    PubMed

    Kuti, J O; Kuti, H O

    1999-01-01

    Proximate composition and mineral content of raw and cooked leaves of two edible tree spinach species (Cnidoscolus chayamansa and C. aconitifolius), known locally as 'chaya', were determined and compared with that of a traditional green vegetable, spinach (Spinicia oleraceae). Results of the study indicated that the edible leafy parts of the two chaya species contained significantly (p<0.05) greater amounts of crude protein, crude fiber, Ca, K, Fe, ascorbic acid and beta-carotene than the spinach leaf. However, no significant (p>0.05) differences were found in nutritional composition and mineral content between the chaya species, except minor differences in the relative composition of fatty acids, protein and amino acids. Cooking of chaya leaves slightly reduced nutritional composition of both chaya species. Cooking is essential prior to consumption to inactivate the toxic hydrocyanic glycosides present in chaya leaves. Based on the results of this study, the edible chaya leaves may be good dietary sources of minerals (Ca, K and Fe) and vitamins (ascorbic acid and beta-carotene). PMID:10540979

  2. Novel defensin subfamily from spinach ( Spinacia oleracea)

    Microsoft Academic Search

    Ana Segura; Manuel Moreno; Antonio Molina; Francisco Garc??a-Olmedo

    1998-01-01

    Antimicrobial peptides (So-D1-7) were isolated from a crude cell wall preparation from spinach leaves (Spinacia oleracea cv. Matador) and, judged from their amino acid sequences, six of them (So-D2-7) represented a novel structural subfamily of plant defensins (group IV). Group-IV defensins were also functionally distinct from those of groups I–III. They were active at concentrations <20 ?M against Gram-positive (Clavibacter

  3. Exoamylase activity in vacuoles isolated from pea and wheat leaf protoplasts.

    PubMed

    Ziegler, P; Beck, E

    1986-12-01

    Vacuoles isolated from pea (Pisum sativum), and wheat (Triticum aestivum) leaf protoplasts contained considerable activities of electrophoretically highly mobile exoamylases. Vacuoles from spinach (Spinacia oleracea) leaf and photoautotrophic Chenopodium rubrum suspension culture cell protoplasts were devoid of amylolytic activity. Endoamylase activity was in all cases associated primarily with the chloroplast. PMID:16665144

  4. Inhibition of Escherichia coli O157:H7 and Salmonella enterica on spinach and identification of antimicrobial substances produced by a commercial Lactic Acid Bacteria food safety intervention.

    PubMed

    Cálix-Lara, Thelma F; Rajendran, Mahitha; Talcott, Stephen T; Smith, Stephen B; Miller, Rhonda K; Castillo, Alejandro; Sturino, Joseph M; Taylor, T Matthew

    2014-04-01

    The microbiological safety of fresh produce is of concern for the U.S. food supply. Members of the Lactic Acid Bacteria (LAB) have been reported to antagonize pathogens by competing for nutrients and by secretion of substances with antimicrobial activity, including organic acids, peroxides, and antimicrobial polypeptides. The objectives of this research were to: (i) determine the capacity of a commercial LAB food antimicrobial to inhibit Escherichia coli O157:H7 and Salmonella enterica on spinach leaf surfaces, and (ii) identify antimicrobial substances produced in vitro by the LAB comprising the food antimicrobial. Pathogens were inoculated on freshly harvested spinach, followed by application of the LAB antimicrobial. Treated spinach was aerobically incubated up to 12 days at 7 °C and surviving pathogens enumerated via selective/differential plating. l-Lactic acid and a bacteriocin-like inhibitory substance (BLIS) were detected and quantified from cell-free fermentates obtained from LAB-inoculated liquid microbiological medium. Application of 8.0 log10 CFU/g LAB produced significant (p < 0.05) reductions in E. coli O157:H7 and Salmonella populations on spinach of 1.6 and 1.9 log10 CFU/g, respectively. It was concluded the LAB antimicrobial inhibited foodborne pathogens on spinach during refrigerated storage, likely the result of the production of metabolites with antimicrobial activity. PMID:24290643

  5. Frequency of Verticillium Species in Commercial Spinach Fields and Transmission of V. dahliae from Spinach to Subsequent Lettuce Crops.

    PubMed

    Short, D P G; Gurung, S; Koike, S T; Klosterman, S J; Subbarao, K V

    2015-01-01

    ABSTRACT Verticillium wilt caused by V. dahliae is a devastating disease of lettuce in California (CA). The disease is currently restricted to a small geographic area in central coastal CA, even though cropping patterns in other coastal lettuce production regions in the state are similar. Infested spinach seed has been implicated in the introduction of V. dahliae into lettuce fields but direct evidence linking this inoculum to wilt epidemics in lettuce is lacking. In this study, 100 commercial spinach fields in four coastal CA counties were surveyed to evaluate the frequency of Verticillium species recovered from spinach seedlings and the area under spinach production in each county was assessed. Regardless of the county, V. isaacii was the most frequently isolated species from spinach followed by V. dahliae and, less frequently, V. klebahnii. The frequency of recovery of Verticillium species was unrelated to the occurrence of Verticillium wilt on lettuce in the four counties but was related to the area under spinach production in individual counties. The transmission of V. dahliae from infested spinach seeds to lettuce was investigated in microplots. Verticillium wilt developed on lettuce following two or three plantings of Verticillium-infested spinach, in independent experiments. The pathogen recovered from the infected lettuce from microplots was confirmed as V. dahliae by polymerase chain reaction assays. In a greenhouse study, transmission of a green fluorescence protein-tagged mutant strain of V. dahliae from spinach to lettuce roots was demonstrated, after two cycles of incorporation of infected spinach residue into the soil. This study presents conclusive evidence that V. dahliae introduced via spinach seed can cause Verticillium wilt in lettuce. PMID:25098494

  6. Release of Spinach Germplasm With Resistance to Leafminers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Agricultural Research Service, United States Department of Agriculture announces the release of a spinach (Spinacia oleracea L.) breeding line 03-04-63. 03-04-63 is a semi-flat type of spinach with dark green, semi-erect leaves. The line may be suitable for commercial production, and is suitable...

  7. LEAFMINER-RESISTANT SPINACH GERMPLASM 03-04-63

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Agricultural Research Service, United States Department of Agriculture announces the release of a spinach (Spinacia oleracea L.) breeding line 03-04-63. 03-04-63 is a semi-flat type of spinach with dark green, semi-erect leaves. The line may be suitable for commercial production, and is suitable...

  8. Detection and quantification of Verticillium dahliae in spinach seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is a soilborne fungus that causes Verticillium wilt on multiple crops in central coastal California. Although spinach crops grown in this region for fresh and processing commercial production do not display Verticillium wilt symptoms, spinach seeds produced in the United States ...

  9. Studies of a New Fusarium Wilt of Spinach in Texas. 

    E-print Network

    Taubenhaus, J. J. (Jacob Joseph)

    1926-01-01

    associated with Fusarium wilt. ...................... 21 1 1 Methods of control. .......................................... 21 j Summary .................................................. 22 I Acknowledgment... spinach wilt infects any of the parts of the plant above ground, although he points out that F~csarium spinaciae is an organism which invades the ' vascular system of the spinach root. The Fusarium here described, on the other hand, is found to invade...

  10. Spinach as a source of carotenoids, folate and antioxidant activity

    Microsoft Academic Search

    J. J. M. Castenmiller

    2000-01-01

    Fruits and vegetables are generally considered important contributors to a healthy diet and an increased intake of fruits and vegetables is related to a decreased risk of cancers, cardiovascular disease, and other diseases. In this thesis two aspects of spinach, a dark-green, leafy vegetable, are examined. The first aspect is the bioavailability of the carotenoids and folate present in spinach.

  11. NOTICE OF RELEASE OF SPINACH GERMPLASM WITH RESISTANCE TO LEAFMINERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Agricultural Research Service, United States Department of Agriculture announces the release of a spinach (Spinacia oleracea L.) breeding line 03-04-9. 03-04-9 is an oriental type of spinach with dark green, semi-erect leaves. The line may be suitable for commercial production, and is suitable...

  12. LEAFMINER-RESISTANT SPINACH GERMPLASM 03-04-9.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Agricultural Research Service, United States Department of Agriculture announces the release of a spinach (Spinacia oleracea L.) breeding line 03-04-9. 03-04-9 is an oriental type of spinach with dark green, semi-erect leaves. The line may be suitable for commercial production, and is suitable f...

  13. Response of spinach and komatsuna to biogas effluent made from source-separated kitchen garbage.

    PubMed

    Furukawa, Yuichiro; Hasegawa, Hiroshi

    2006-01-01

    Recycling of kitchen garbage is an urgent task for reducing public spending and environmental burdens by incineration and/or landfill. There is an interesting regional effort in Ogawa, Saitama prefecture, Japan, in which source-separated kitchen garbage is anaerobically fermented with a biogas plant and the resultant effluent is used as a quick-release organic fertilizer by surrounding farmers. However, scientific assessments of fertilizer values and risks in the use of the effluent were lacking. Thus, a field experiment was conducted from 2003 to 2004 in Tohoku National Agricultural Research Center to grow spinach (Spinacia oleracea L.) and komatsuna (Brassica rapa var. perviridis L. H. Bailey) for evaluating the fertilizer value of the kitchen garbage effluent (KGE), nitrate, coliform group (CG), Escherichia coli, fecal streptococci (FS), and Vibrio parahaemolyticus concentrations of KGE and in the soil and the plant leaves. A cattle manure effluent (CME) and chemical fertilizers (NPK) were used as controls. Total nitrogen (N) and ammonium N concentrations of the KGE were 1.47 and 1.46 g kg(-1), respectively. The bacteria tested were detected in both biogas effluents in the order of 2 to 3 log CFU g(-1), but there was little evidence that the biogas effluents increased these bacteria in the soil and the plant leaves. At the rate of 22 g N m(-2), yield, total N uptake, apparent N recovery rate, and leaf nitrate ion concentration at harvest of spinach and komatsuna in the KGE plot were mostly comparable to those in the NPK and CME plots. We conclude that the KGE is a quick-release N fertilizer comparable to chemical fertilizers and does not cause contamination of CG, E. coli, FS, or V. parahaemolyticus in the soil and spinach and komatsuna leaves. PMID:16973635

  14. Growth Conditions To Reduce Oxalic Acid Content of Spinach

    NASA Technical Reports Server (NTRS)

    Johnson-Rutzke, Corinne

    2003-01-01

    A controlled-environment agricultural (CEA) technique to increase the nutritive value of spinach has been developed. This technique makes it possible to reduce the concentration of oxalic acid in spinach leaves. It is desirable to reduce the oxalic acid content because oxalic acid acts as an anti-nutritive calcium-binding component. More than 30 years ago, an enzyme (an oxidase) that breaks down oxalic acid into CO2 and H2O2 was discovered and found to be naturally present in spinach leaves. However, nitrate, which can also be present because of the use of common nitratebased fertilizers, inactivates the enzyme. In the CEA technique, one cuts off the supply of nitrate and keeps the spinach plants cool while providing sufficient oxygen. This technique provides the precise environment that enables the enzyme to naturally break down oxalate. The result of application of this technique is that the oxalate content is reduced by 2/3 in one week.

  15. Role of curli and plant cultivation conditions on Escherichia coli O157:H7 internalization into spinach grown on hydroponics and in soil.

    PubMed

    Macarisin, Dumitru; Patel, Jitendra; Sharma, Vijay K

    2014-03-01

    Contamination of fresh produce could represent a public health concern because no terminal kill step is applied during harvest or at the processing facility to kill pathogens. In addition, once contaminated, pathogens may internalize into produce and be protected from disinfectants during the postharvest processing step. The objective of the current study was to determine the potential internalization of Escherichia coli O157:H7 into spinach roots and subsequent transfer to the edible parts. Because curli are involved in biofilm formation, we investigated whether their presence influence the internalization of E. coli O157:H7 into spinach. Further, the effect of the spinach cultivar on E. coli O157:H7 internalization was evaluated. Spinach plants were grown in contaminated soil as well as hydroponically to prevent mechanical wounding of the roots and inadvertent transfer of pathogens from the contamination source to the non-exposed plant surfaces. Results showed that E. coli O157:H7 could internalize into hydroponically grown intact spinach plants through the root system and move to the stem and leaf level. The incidence of internalization was significantly higher in hydroponically grown plants when roots were exposed to 7 log CFU/mL compared to those exposed to 5 log CFU/mL. The effect of cultivar on E. coli O157:H7 internalization was not significant (P>0.05) for the analyzed spinach varieties, internalization incidences showing almost equal distribution between Space and Waitiki, 49.06% and 50.94% respectively. Wounding of the root system in hydroponically grown spinach increased the incidence of E. coli O157:H7 internalization and translocation to the edible portions of the plant. Experimental contamination of the plants grown in soil resulted in a greater number of internalization events then in those grown hydroponically, suggesting that E. coli O157:H7 internalization is dependent on root damage, which is more likely to occur when plants are grown in soil. Curli expression by E. coli O157:H7 had no significant effect on its root uptake by spinach plants. PMID:24412958

  16. Effects of a Short-Term Shift to Low Temperature and of Long-Term Cold Hardening on Photosynthesis and Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase and Sucrose Phosphate Synthase Activity in Leaves of Winter Rye (Secale cereale L.).

    PubMed Central

    Hurry, V. M.; Malmberg, G.; Gardestrom, P.; Oquist, G.

    1994-01-01

    The effect of a short-term (hours) shift to low temperature (5[deg]C) and long-term (months) cold hardening on photosynthesis and carbon metabolism was studied in winter rye (Secale cereale L. cv Musketeer). Cold-hardened plants grown at 5[deg]C exhibited 25% higher in situ CO2 exchange rates than nonhardened plants grown at 24[deg]C. Cold-hardened plants maintained these high rates throughout the day, in contrast to nonhardened plants, which showed a gradual decline in photosynthesis after 3 h. Associated with the increase in photosynthetic capacity following cold hardening was an increase in ribulose-1,5-bisphosphate carboxylase/oxygenase and sucrose phosphate synthase activity and 3- to 4-fold increases in the pools of associated metabolites. Leaves of nonhardened plants shifted overnight to 5[deg]C required 9 h in the light at 5[deg]C before maximum rates of photosynthesis were reached. The gradual increase in photosynthesis in leaves shifted to 5[deg]C was correlated with a sharp decline in the 3-phosphoglycerate/triose phosphate ratio and by an increase in the ribulose bisphosphate/3-phosphoglycerate ratio, indicating the gradual easing of aninorganic phosphate-mediated feedback inhibition on photo-synthesis. We suggest that the strong recovery of photosynthesis in winter rye following cold hardening indicates that the buildup of photosynthetic enzymes, as well as those involved in sucrose synthesis, is an adaptive response that enables these plants to maximize the production of sugars that have both cryoprotective and storage functions that are critical to the performance of these cultivars during over-wintering. PMID:12232378

  17. Novel antifungal peptides from Ceylon spinach seeds.

    PubMed

    Wang, H; Ng, T B

    2001-11-01

    Two novel antifungal peptides, designated alpha- and beta-basrubrins, respectively, were isolated from seeds of the Ceylon spinach Basella rubra. The purification procedure involved saline extraction, (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion exchange chromatography on CM-cellulose and FPLC-gel filtration on Superdex peptide column. alpha- and beta-basrubrins exhibited a molecular weight of 4.3 and 5 kDa, respectively. They inhibited translation in a rabbit reticulocyte system with an IC(50) value of 400 and 100 nM, respectively. alpha- and beta-basrubrin inhibited HIV-1 reverse transcriptase by (79.4 +/- 7.8)% and (54.6 +/- 3.6)%, respectively, at a concentration of 400 microM, and (10.56 +/- 0.92)% and (2.12 +/- 0.81)%, respectively, at a concentration of 40 microM. Both alpha- and beta-basrubrins exerted potent antifungal activity toward Botrytis cinerea, Mycosphaerella arachidicola, and Fusarium oxysporum. PMID:11688973

  18. Alternative pathway respiration is associated with ammonium ion sensitivity in spinach and pea plants

    Microsoft Academic Search

    Berta Lasa; Silvia Frechilla; Pedro. M. Aparicio-Tejo; Carmen Lamsfus

    2002-01-01

    Spinach and pea plants were grown in hydroponic culture with nitrate orammonium salts as the nitrogen source. Dry matter accumulation andphotosynthetic rate declined in spinach plants fed with ammonium salts, whereasthey did not change in pea plants compared with nitrate-fed plants. Measurementof organic nitrogen and free amino acid content showed that ammonium ions wereassimilated in shoots in spinach plants and

  19. Colonization of spinach (Spinacia oleracea L.) by GFP-tagged verticillium dahliae.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The soilborne fungus, Verticillium dahliae, causes wilt in a wide range of hosts, including spinach (Spinacia oleracea L.). The interaction between a green fluorescent protein (GFP)-tagged V. dahliae strain and spinach was studied by confocal laser scanning microscopy. The roots of spinach seedlings...

  20. Discrepancy between nitrate reduction rates in intact leaves and nitrate reductase activity in leaf extracts: What limits nitrate reduction in situ?

    Microsoft Academic Search

    Werner M. Kaiser; Andrea Kandlbinder; Maria Stoimenova; Johanna Glaab

    2000-01-01

    .   Nitrate reductase (NR) activity in spinach leaf extracts prepared in the presence of a protein phosphatase inhibitor (50??M\\u000a cantharidine) was measured in the presence of Mg2+ (NRact) or EDTA (NRmax), under substrate saturation. These in-vitro activities were compared with nitrate reduction rates\\u000a in leaves from nitrate-sufficient plants. Spinach leaves containing up to 60??mol nitrate per g fresh weight were

  1. Atriplex hortensis L. as a leafy vegetable, and as a leaf protein concentrate plant

    Microsoft Academic Search

    Rolf Carlsson; E. M. Wendy Clarke

    1983-01-01

    The quality ofAtriplex hortensis L. (Mountain Spinach) as a leafy vegetable, forage crop, and plant for production of leaf protein\\/nutrient concentrate was investigated. The plant can substitute or supplementSpinacia oleracea L. as a leafy vegetable, due to similar chemical composition and a higher leaf yield. The whole plant, as a meal, is similar toMedicago sativa L. in chemical composition. It

  2. Role of ascorbate in detoxifying ozone in the apoplast of spinach (Spinacia oleracea L. ) leaves

    SciTech Connect

    Luwe, M.W.F.; Takahama, Umeo; Heber, U. (Univ. of Wuerzburg (Germany))

    1993-03-01

    Both reduced and oxidized ascorbate (AA and DHA) are present in the aqueous phase of the extracellular space, the apoplast, of spinach (Spinacia oleracea L.) leaves. Fumigation with 0.3 [mu]L L[sup [minus]1] of ozone resulted in ozone uptake by the leaves close to 0.9 pmol cm[sup [minus]2] of leaf surface area s[sup [minus]1]. Apoplastic AA was slowly oxidized by ozone. The initial decrease of apoplastic AA was <0.1 pmol cm[sup [minus]2] s[sup [minus]1]. The apoplastic ratio of AA to (AA + DHA) decreased within 6 h of fumigation from 0.9 to 0.1. Initially, the concentration of (AA + DHA) did not change in the apoplast, but when fumigation was continued, DHA increased and AA remained at a very low constant level. After fumigation was discontinued, DHA decreased very slowly in the apoplast, reaching control level after 70 h. Insufficient AA reached the apoplast from the cytosol to detoxify ozone in the apoplast when the ozone flux into the leaves was 0.9 pmol cm[sup [minus]2] s[sup [minus]1]. The transport of DHA back into the cytosol was slower than AA transport into the apoplast. No dehydroascorbate reductase activity could be detected in the apoplast of spinach leaves. In contrast to its extracellular redox state, the intracellular redox state of AA did not change appreciably during a 24-h fumigation period. However, intracellular glutathione became slowly oxidized. At the beginning of fumigation, 90% of the total glutathione was reduced. Only 10% was reduced after 24-h exposure of the leaves to 0.3 [mu]L L[sup [minus]1] of ozone. Necrotic leaf damage started to become visible when fumigation was extended beyond a 24-h period. A close correlation between the extent of damage, on the one hand, and the AA content and the ascorbate redox state of whole leaves, on the other, was observed after 48 h of fumigation. Only the youngest leaves that contained high ascorbate concentrations did not exhibit necrotic leaf damage after 48 h. 30 refs., 6 figs., 1 tab.

  3. Leaf Phosphate Status, Photosynthesis, and Carbon Partitioning in Sugar Beet

    PubMed Central

    Rao, I. Madhusudana; Fredeen, Arthur L.; Terry, Norman

    1990-01-01

    The effect of low phosphate supply (low P) was determined on the diurnal changes in the rate of carbon export, and on the contents of starch, sucrose, glucose, and fructose 2,6-bisphosphate (F2,6BP) in leaves. Low-P effects on the activities of a number of enzymes involved in starch and sucrose metabolism were also measured. Sugar beets (Beta vulgaris L. cv. F58-554H1) were cultured hydroponically in growth chambers and the low-P treatment induced nutritionally. Low-P treatment decreased carbon export from the leaf much more than it decreased photosynthesis. At growth chamber photon flux density, low P decreased carbon export by 34% in light; in darkness, export rates fell but more so in the control so that the average rate in darkness was higher in low-P leaves. Low P increased starch, sucrose, and glucose contents per leaf area, and decreased F2, 6BP. The total extractable activities of enzymes involved in starch and sucrose synthesis were increased markedly by low P, e.g. adenosine 5-diphosphoglucose pyrophosphorylase, cytoplasmic fructose-1,6-bisphosphatase, uridine 5-diphosphoglucose pyrophosphorylase, and sucrose-phosphate synthase. The activities of some enzymes involved in starch and sucrose breakdown were also increased by low P. We propose that plants adapt to low-P environments by increasing the total activities of several phosphatases and by increasing the concentrations of phosphate-free carbon compounds at the expense of sugar phosphates, thereby conserving Pi. The partitioning of carbon among the various carbon pools in low-P adapted leaves appears to be determined in part by the relative capacities of the enzymes for starch and sucrose metabolism. PMID:16667261

  4. Improving spinach, radish, and lettuce growth under red light-emitting diodes (LEDs) with blue light supplementation

    NASA Technical Reports Server (NTRS)

    Yorio, N. C.; Goins, G. D.; Kagie, H. R.; Wheeler, R. M.; Sager, J. C.

    2001-01-01

    Radish (Raphanus sativus L. cv. Cherriette), lettuce (Lactuca sativa L. cv. Waldmann's Green), and spinach (Spinacea oleracea L. cv. Nordic IV) plants were grown under 660-nm red light-emitting diodes (LEDs) and were compared at equal photosynthetic photon flux (PPF) with either plants grown under cool-white fluorescent lamps (CWF) or red LEDs supplemented with 10% (30 micromoles m-2 s-1) blue light (400-500 nm) from blue fluorescent (BF) lamps. At 21 days after planting (DAP), leaf photosynthetic rates and stomatal conductance were greater for plants grown under CWF light than for those grown under red LEDs, with or without supplemental blue light. At harvest (21 DAP), total dry-weight accumulation was significantly lower for all species tested when grown under red LEDs alone than when grown under CWF light or red LEDs + 10% BF light. Moreover, total dry weight for radish and spinach was significantly lower under red LEDs + 10% BF than under CWF light, suggesting that addition of blue light to the red LEDs was still insufficient for achieving maximal growth for these crops.

  5. Characterization of starch breakdown in the intact spinach chloroplast

    Microsoft Academic Search

    D. G. Peavey; M. Steup; M. Gibbs

    1977-01-01

    Starch degradation with a rate of 1 to 2 microgram-atom carbon per milligram chlorophyll per hour was monitored in the isolated intact spinach (Spinacia oleracea) chloroplast which had been preloaded with ¹⁴C-starch photosynthetically from ¹⁴COâ. Starch breakdown was dependent upon inorganic phosphate and the ¹⁴C-labeled intermediates formed were principally those of the Embden-Meyerhof pathway from glucose phosphate to glycerate 3-phosphate.

  6. The plasma membrane-associated NADH oxidase of spinach leaves responds to blue light

    NASA Technical Reports Server (NTRS)

    Morre, D. James; Penel, Claude; Greppin, Hubert; Morre, Dorothy M.

    2002-01-01

    The plasma membrane-associated NADH oxidase (NOX) of spinach leaf disks is characterized by oscillations in activity with a regular period length of ca. 24 min. Within a single population of plants exposed to light at the same time, NOX activities of all plants function synchronously. Exposure of plants transferred from darkness to blue light (495 nm, 2 min, 50 micromoles m-2 s-1) resulted in a complex response pattern but with a new maximum in the rate of NOX activity 36 (24+12) min after illumination and then with maxima in the rate of NOX activity every 24 min thereafter. Transient maxima in NOX activity were observed as well after 9.3 + /- 1.4 and 20.7 +/- 2.1 min. The blue light response differed from the response to red (650 nm, 10 min, 50 micromoles m-2 s-1) or white light where activity maxima were initiated 12 min after the light exposure followed by maxima every 24 min thereafter. Green or yellow light was ineffective. The light response was independent of the time in the 24-min NOX cycle when the light was given. The net effects of blue and red light were ultimately the same with a new maximum in the rate of NOX activity at 12+24=36 min (and every 24 min thereafter), but the mechanisms appear to be distinct.

  7. 77 FR 29588 - Notice of Decision To Issue Permits for the Importation of Fresh Celery, Arugula, and Spinach...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-18

    ...Fresh Celery, Arugula, and Spinach From Colombia into the Continental United States AGENCY...fresh celery, arugula, and spinach from Colombia. Based on the findings of three pest...fresh celery, arugula, and spinach from Colombia. DATES: Effective Date: May 18,...

  8. Biofilm formation Escherichia coli O157:H7 and Salmonella on spinach harvester blades

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Outbreaks associated with leafy greens have focused attention on the transfer of human pathogens to leafy greens during mechanical harvesting. Harvesting of baby spinach presents an opportunity for contaminated blades to transfer bacterial foodborne pathogens to recently harvested spinach. Biofilm f...

  9. Development of a qPCR assay for quantification of verticillium dahliae in spinach seed.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt, caused by the soilborne fungus Verticillium dahliae, is an important disease of lettuce and other specialty crops in the Salinas Valley of California. Although spinach is not affected by Verticillium wilt in commercial production, spinach seed infected with V. dahliae from locatio...

  10. A real-time PCR assay for detection and quantification of verticillium dahliae in spinach seed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is a soilborne fungus that causes Verticillium wilt on multiple crops in central coastal California. Although spinach crops grown in this region for fresh and processing commercial production do not display Verticillium wilt symptoms, spinach seed produced in the U.S. or Europe ...

  11. A qPCR assay for detection and quantification of Verticillium dahliae in spinach seed.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Verticillium dahliae is the causal agent of Verticillium wilt of lettuce and other specialty crops in the Salinas Valley of California. Spinach, another major specialty crop in California, is not affected by Verticillium wilt in commercial production. However, spinach seed infected with ...

  12. Phytologia (December 2011) 93(3) 283 SEVENTEEN YEARS STORAGE OF JUNIPER AND SPINACH

    E-print Network

    Adams, Robert P.

    Phytologia (December 2011) 93(3) 283 SEVENTEEN YEARS STORAGE OF JUNIPER AND SPINACH LEAVES. In contrast, juniper leaves stored in 100 and 95% ethanol yielded more and higher molecular weight DNA than 70 in ethanol solutions may reflect the herbaceous nature of spinach leaves versus the woody nature of juniper

  13. Retention of Folate, Carotenoids, and Other Quality Characteristics in Commercially Packaged Fresh Spinach

    Microsoft Academic Search

    S. PANDRANGI; L. F. LABORDE

    2004-01-01

    The effect of storage temperature (4 °C, 10 °C, and 20 °C) on retention of folate, carotenoids, and other quality characteristics in commercially packaged fresh spinach were determined. Based on visual color and appearance, spinach was unacceptable after 8 d, 6 d, and 4 d at 4 °C, 10 °C, and 20 °C, respectively. Color differences ( E), chlorophyll degradation,

  14. SCREENING AND BREEDING FOR RESISTANCE TO LEAFMINER (KIRIOMYZA LANGEI) IN LETTUCE AND SPINACH.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leafminer (Liriomyza langei Frick) is a major pest that causes considerable damage to a wide variety of vegetable crops including lettuce and spinach. Forty-eight lettuce cultivars and introduction lines and 338 spinach accessions were screened in an insect cage for leafminer resistance. Significant...

  15. Leaf Activities.

    ERIC Educational Resources Information Center

    Mingie, Walter

    Leaf activities can provide a means of using basic concepts of outdoor education to learn in elementary level subject areas. Equipment needed includes leaves, a clipboard with paper, and a pencil. A bag of leaves may be brought into the classroom if weather conditions or time do not permit going outdoors. Each student should pick a leaf, examine…

  16. Localization of phosphatidylcholine in outer envelope membrane of spinach chloroplasts

    PubMed Central

    1985-01-01

    We have examined the effects of phospholipase C from Bacillus cereus on the extent of phospholipid hydrolysis in envelope membrane vesicles and in intact chloroplasts. When isolated envelope vesicles were incubated in presence of phospholipase C, phosphatidylcholine and phosphatidylglycerol, but not phosphatidylinositol, were totally converted into diacylglycerol if they were available to the enzyme (i.e., when the vesicles were sonicated in presence of phospholipase C). These experiments demonstrate that phospholipase C can be used to probe the availability of phosphatidylcholine and phosphatidylglycerol in the cytosolic leaflet of the outer envelope membrane from spinach chloroplasts. When isolated, purified, intact chloroplasts were incubated with low amounts of phospholipase C (0.3 U/mg chlorophyll) under very mild conditions (12 degrees C for 1 min), greater than 80% of phosphatidylcholine molecules and almost none of phosphatidylglycerol molecules were hydrolyzed. Since we have also demonstrated, by using several different methods (phase-contrast and electron microscopy, immunochemical and electrophoretic analyses) that isolated spinach chloroplasts, and especially their outer envelope membrane, remained intact after mild treatment with phospholipase C, we can conclude that there is a marked asymmetric distribution of phospholipids across the outer envelope membrane of spinach chloroplasts. Phosphatidylcholine, the major polar lipid of the outer envelope membrane, is almost entirely accessible from the cytosolic side of the membrane and therefore is probably localized in the outer leaflet of the outer envelope bilayer. On the contrary, phosphatidylglycerol, the major polar lipid in the inner envelope membrane and the thylakoids, is probably not accessible to phospholipase C from the cytosol and therefore is probably localized mostly in the inner leaflet of the outer envelope membrane and in the other chloroplast membranes. PMID:3988805

  17. Alleviation of cadmium phytotoxicity by magnesium in Japanese mustard spinach

    Microsoft Academic Search

    M. D. Abul KASHEM; Shigenao Kawai

    2007-01-01

    To clarify the mechanism of Magnesium (Mg) in alleviating cadmium (Cd) phytotoxicity, Japanese mustard spinach (Brassica rapa L. var. pervirdis) was grown for 10 days after treatment in hydroponics in a growth chamber under natural light. The treatments were: (1) nutrient solution alone (Control), (2) 10 mmol L Mg (High-Mg), (3) 2.5 µmol L Cd (Cd-toxic), (4) 2.5 µmol L Cd plus 10 mmol L Mg (Mg-alleviated). The Cd-toxic

  18. Chromatographic determination of changes in pigments in spinach (Spinacia oleracea L.) during processing.

    PubMed

    Kidmose, Ulla; Edelenbos, Merete; Christensen, Lars P; Hegelund, Erling

    2005-10-01

    The content of individual chlorophyll and carotenoid pigments is determined in three spinach varieties (Lorelei, Springfield, and Ballet) after processing. Raw spinach and spinach that is steam-blanched for 3, 9, or 15 min is stored frozen at -24 degrees C for 6 months. In addition, spinach is air-dried at 75 degrees C, packed in atmospheric air or nitrogen, and stored at ambient temperature for 6 months. Processing has a significant effect on the content of individual chlorophyll and carotenoid pigments; however, there are no differences between varieties in their content of total and individual pigments in raw, frozen spinach. Increasing blanching time resulted in decreased contents of chlorophyll a and b and increased contents of chlorophyll a' and b' and pheophytin a and b because of pheophytinization. Changes in the color because of pheophytinization are only detected after 15 min blanching. The carotenoid pigments are more stable than the chlorophyll pigments during blanching. (all-E)-Violaxanthin is significantly reduced, caused by degradation to other xanthophylls, such as neochrome, during blanching. There are no significant differences in the content of chlorophyll a and b of dried spinach and blanched, frozen spinach. Formation of chlorophyll a' and b', pheophytin a and b, and chlorophyll a-1 and b-1 is observed after drying. The content of pheophytin a and b is significantly lower in dried versus blanched frozen samples. In dried spinach that is stored in atmospheric air, the content of beta-carotene [599 mg/kg dry matter (DM)] is significantly lower compared with nitrogen (766 mg/kg DM), and the content of (all-E)-lutein is lower than in blanched frozen spinach. Neochrome is not detected in raw spinach but in steam-blanched and dried spinach. No differences are observed in the content of (all-E)-neoxanthin, (9'Z)-neoxanthin, (all-E)-violaxanthin, (all-E)-lutein epoxide, or neolutein A and B between spinach that is stored frozen after 3 min blanching and dried spinach. PMID:16212792

  19. A real-time PCR assay for detection and quantification of Verticillium dahliae in spinach seed.

    PubMed

    Duressa, Dechassa; Rauscher, Gilda; Koike, Steven T; Mou, Beiquan; Hayes, Ryan J; Maruthachalam, Karunakaran; Subbarao, Krishna V; Klosterman, Steven J

    2012-04-01

    Verticillium dahliae is a soilborne fungus that causes Verticillium wilt on multiple crops in central coastal California. Although spinach crops grown in this region for fresh and processing commercial production do not display Verticillium wilt symptoms, spinach seeds produced in the United States or Europe are commonly infected with V. dahliae. Planting of the infected seed increases the soil inoculum density and may introduce exotic strains that contribute to Verticillium wilt epidemics on lettuce and other crops grown in rotation with spinach. A sensitive, rapid, and reliable method for quantification of V. dahliae in spinach seed may help identify highly infected lots, curtail their planting, and minimize the spread of exotic strains via spinach seed. In this study, a quantitative real-time polymerase chain reaction (qPCR) assay was optimized and employed for detection and quantification of V. dahliae in spinach germplasm and 15 commercial spinach seed lots. The assay used a previously reported V. dahliae-specific primer pair (VertBt-F and VertBt-R) and an analytical mill for grinding tough spinach seed for DNA extraction. The assay enabled reliable quantification of V. dahliae in spinach seed, with a sensitivity limit of ?1 infected seed per 100 (1.3% infection in a seed lot). The quantification was highly reproducible between replicate samples of a seed lot and in different real-time PCR instruments. When tested on commercial seed lots, a pathogen DNA content corresponding to a quantification cycle value of ?31 corresponded with a percent seed infection of ?1.3%. The assay is useful in qualitatively assessing seed lots for V. dahliae infection levels, and the results of the assay can be helpful to guide decisions on whether to apply seed treatments. PMID:22236050

  20. Correlating Arsenic-Induced Morphological Change in Spinach Leaves With Leaf Spectral Characteristics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arsenic (As) is a widely spread soil contaminant which can be accumulated into plant parts. The presence of As in edible portions of plants allows for potentially dangerous ingestion by humans and animals. The ability to detect As in plants is an important tool to minimize such risks. Remote sens...

  1. Fishy and hay-like off-flavours of dry spinach

    Microsoft Academic Search

    C. Masanetz; H. Guth; W. Grosch

    1998-01-01

    Gas chromatography-olfactometry of headspace samples revealed that (Z)-3-hexenal, methanethiol, (Z)-1,5-octadien-3-one, dimethyl trisulphide, octanal, 2-isopropyl- and 2-sec-butyl-3-methoxypyrazine are potent odorants of\\u000a raw spinach. Boiling the spinach led to a change, such that dimethyl sulphide, methanethiol, dimethyl trisulphide, methional\\u000a and 2-acetyl-1-pyrroline became the most important odorants. A further change was observed after drying and storage of raw\\u000a spinach: methylpropanal, 2- and 3-methylbutanal

  2. The complete sequence of the genomic RNAs of spinach latent virus.

    PubMed

    Ge, X; Scott, S W; Zimmerman, M T

    1997-01-01

    We describe the sequence for the complete genome of spinach latent virus (SpLV). Comparisons of this genome with that of the only other complete genome described for a species within the genus Ilarvirus (citrus leaf rugose virus-CiLRV) indicate that while there are marked differences between the RNA 3 of the two viruses, their respective RNAs 1 and 2 share many similarities. However, the putative 2a protein of SpLV contains a C2H2 type "zinc finger"-like motif located towards the carboxy terminal of the protein which is absent in CiLRV and has not been reported for other members of the family Bromoviridae. A second open reading frame (2b), located at a similar position to that described for the cucumoviruses, occurs in the RNA 2 of both SpLV and CiLRV. The putative coat protein of SpLV is similar to that of citrus variegation virus (CVV) and asparagus virus 2 (AV-2), both members of subgroup 2 of the ilarviruses. We have subsequently demonstrated a serological relationship between SpLV and other viruses in subgroup 2 and suggest that SpLV should be included in this subgroup rather than remain in a separate group (subgroup 6). However, while the putative movement protein of SpLV is remarkably similar to that of AV-2, it shows little relationship with the corresponding protein of CVV and the lack of similarity suggests that a recombination event may have occurred in the past. The relationship between the genera Alfamovirus and Ilarvirus is discussed in the light of the data for the genome of SpLV and recently published information for other members of the genus Ilarvirus. PMID:9229009

  3. Characterization of an Acyl-Coenzyme A Thioesterase Associated with the Envelope of Spinach Chloroplasts 1

    PubMed Central

    Joyard, Jacques; Stumpf, Paul K.

    1980-01-01

    The enzymic hydrolysis of acyl-coenzyme A occurs in intact and purified chloroplasts. The different components of spinach chloroplasts were separated after a slight osmotic shock and the purified envelope membranes were shown to be the site of very active acyl-CoA thioesterase activity (EC 3.1.2.2.). The enzyme, which had a pH optimum of 9.0, was not affected by sulfhydryl reagents or by serine esterase inhibitors. However, the acyl-CoA thioesterase was strongly inhibited by unsaturated fatty acids, especially oleic acid, at concentrations above 100 micromolar. In marked contrast, saturated fatty acids had only a slight effect on the thioesterase activity. Substrate specificities showed that the velocity of the reaction increased with the chain length of the substrate from decanoyl-CoA to myristoyl-CoA and then decreased with the chain length from myristoyl-CoA to stearoyl-CoA. Interestingly, oleoyl-CoA was only slowly hydrolyzed. These results suggest that the envelope acyl-CoA thioesterase coupled with an envelope acyl-CoA synthetase may be involved in a switching system which indirectly allows acyl transfer from acyl carrier protein derivatives to unsaturated acyl-CoA derivatives and ensures the predominance of unsaturated 18 carbon fatty acids in plants. Furthermore, the position of both acyl-CoA thioesterase and synthetase in the envelope membranes suggest that these two enzymes may be involved in the transport of oleic acid from the stroma phase to the cytosol compartment of the leaf cell. PMID:16661326

  4. Leaf photosynthesis and carbohydrates of CO?-enriched maize and grain sorghum exposed to a short period of soil water deficit during vegetative development.

    PubMed

    Kakani, Vijaya Gopal; Vu, Joseph C V; Allen, Leon Hartwell; Boote, Kenneth J

    2011-12-15

    Among C? species, sorghum is known to be more drought tolerant than maize. The objective was to evaluate differences in leaf gas exchanges, carbohydrates, and two enzyme activities of these nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME) C? subtype monocots in response to water deficit and CO? concentration ([CO?]). Maize and sorghum were grown in pots in sunlit environmental-controlled chambers. Treatments included well watered (WW) and water stressed (WS) (water withheld at 26 days) and daytime [CO?] of 360 (ambient) and 720 (elevated) ?mol mol?¹. Midday gas exchange rates, concentrations of nonstructural carbohydrates, and activities of sucrose-phosphate synthase (SPS) and adenosine 5'-diphosphoglucose pyrophosphorylase (ADGP) were determined for fully expanded leaf sections. There was no difference in leaf CO? exchange rates (CER) between ambient and elevated [CO?] control plants for both maize and sorghum. After withholding water, leaf CER declined to zero after 8 days in maize and 10 days for sorghum. Sorghum had lower stomatal conductance and transpiration rates than maize, which resulted in a longer period of CER under drought. Nonstructural carbohydrates of both control maize and sorghum were hardly affected by elevated [CO?]. Under drought, however, increases in soluble sugars and decreases in starch were generally observed for maize and sorghum at both [CO?] levels. For stressed maize and sorghum, decreases in starch occurred earlier and were greater at ambient [CO?] than at elevated [CO?]. For maize, drought did not meaningfully affect SPS activity. However, a decline in SPS activity was observed for drought-stressed sorghum under both [CO?] treatments. There was an increase in ADGP activity in maize under drought for both [CO?] treatments. Such a response in ADGP to drought, however, did not occur for sorghum. The generally more rapid response of maize than sorghum to drought might be related to the more rapid growth of leaf area of maize. PMID:21835494

  5. A Mössbauer study of spinach chloroplasts with substituted functionally active Ca2+ for57Fe

    NASA Astrophysics Data System (ADS)

    Novakova, A. A.; Semin, B. K.; Aleksandrov, A. Yu.; Tsurkina, L. A.

    1992-04-01

    A Mössbauer spectroscopy was used to investigate spinach chloroplasts in which Ca2+ ions localized in photosystem-II (actively involved in the structural-functional organization of the photosynthetic chain) were chemically substituted for57Fe ions.

  6. 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

  7. The effect of cerium (III) on the chlorophyll formation in spinach

    Microsoft Academic Search

    Fashui Hong; Ling Wang; Xiangxuan Meng; Zheng Wei; Guiwen Zhao

    2002-01-01

    The effect of Ce3+ on the chlorophyll (chl) of spinach was studied in pot culture experiments. The results showed that Ce3+ could obviously stimulate the growth of spinach and increase its chlorophyll contents and photosynthetic rate. It could also\\u000a improve the PSII formation and enhance its electron transport rate of PSII as well. By inductively coupled plasma-mass spectroscopy\\u000a and atom

  8. Imaging metabolite dynamics in living cells using a Spinach-based riboswitch.

    PubMed

    You, Mingxu; Litke, Jacob L; Jaffrey, Samie R

    2015-05-26

    Riboswitches are natural ligand-sensing RNAs typically that are found in the 5' UTRs of mRNA. Numerous classes of riboswitches have been discovered, enabling mRNA to be regulated by diverse and physiologically important cellular metabolites and small molecules. Here we describe Spinach riboswitches, a new class of genetically encoded metabolite sensor derived from naturally occurring riboswitches. Drawing upon the structural switching mechanism of natural riboswitches, we show that Spinach can be swapped for the expression platform of various riboswitches, allowing metabolite binding to induce Spinach fluorescence directly. In the case of the thiamine 5'-pyrophosphate (TPP) riboswitch from the Escherichia coli thiM gene encoding hydroxyethylthiazole kinase, we show that insertion of Spinach results in an RNA sensor that exhibits fluorescence upon binding TPP. This TPP Spinach riboswitch binds TPP with affinity and selectivity similar to that of the endogenous riboswitch and enables the discovery of agonists and antagonists of the TPP riboswitch using simple fluorescence readouts. Furthermore, expression of the TPP Spinach riboswitch in Escherichia coli enables live imaging of dynamic changes in intracellular TPP concentrations in individual cells. Additionally, we show that other riboswitches that use a structural mechanism similar to that of the TPP riboswitch, including the guanine and adenine riboswitches from the Bacillus subtilis xpt gene encoding xanthine phosphoribosyltransferase, and the S-adenosyl-methionine-I riboswitch from the B. subtilis yitJ gene encoding methionine synthase, can be converted into Spinach riboswitches. Thus, Spinach riboswitches constitute a novel class of RNA-based fluorescent metabolite sensors that exploit the diversity of naturally occurring ligand-binding riboswitches. PMID:25964329

  9. Bioavailability of iron from spinach using an in vitro/human Caco-2 cell bioassay model

    NASA Technical Reports Server (NTRS)

    Rutzke, Corinne J.; Glahn, Raymond P.; Rutzke, Michael A.; Welch, Ross M.; Langhans, Robert W.; Albright, Louis D.; Combs, Gerald F Jr; Wheeler, Raymond M.

    2004-01-01

    Spinach (Spinacia oleracea) cv Whitney was tested for iron bioavailabilty using an in vitro human intestinal cell culture ferritin bioassay technique previously developed. Spinach was cultured in a growth chamber for 33 days, harvested, and freeze-dried. Total iron in the samples was an average of 71 micrograms/g dry weight. Spinach was digested in vitro (pepsin and 0.1 M HCl followed by pancreatin and 0.1 M NaHCO3) with and without the addition of supplemental ascorbic acid. Caco-2 cell cultures were used to determine iron bioavailability from the spinach mixtures. Production of the iron-binding protein ferritin in the Caco-2 cells showed the supplemental ascorbic acid doubled bioavailability of iron from spinach. The data show fresh spinach is a poor source of iron, and emphasize the importance of evaluation of whole meals rather than single food items. The data support the usefulness of the in vitro/Caco-2 cell ferritin bioassay model for prescreening of space flight diets for bioavailable iron.

  10. Accumulation of Rare Earth Elements in Spinach and Soil under Condition of Using REE and Acid Rain Stress

    Microsoft Academic Search

    Yan Chongling; Hong Yetang; Lin Peng; Wang Shijie; Li Xinqing; Liang Jie

    The content and distribution characteristics of REE in spinach and soil under using REE and acid rain stress were studied by pot experiments. The results show that the content of REE is 01527~01696 (?g· g - 1) in the above2ground portion of spinach , 21668~31003 (?g· g - 1) in the under2ground portion of spinach and 229109~ 250130 (?g· g

  11. Detection of genome DNA methylation change in spinach induced by 5-azaC.

    PubMed

    Gao, Wujun; Li, Shufen; Li, Zhongxia; Huang, Yingying; Deng, Chuanliang; Lu, Longdou

    2014-08-01

    DNA methylation has been implicated in the regulation of gene expression, genome imprinting, and chromatin remodeling in eukaryotes. In this study, we analyzed possible alterations in levels and patterns of cytosine methylation in male and female spinach plants after treatment with demethylation agent 5-azacytidine (5-azaC) using two methods: (1) direct determination of 5-methylcytidine (5 mC) amounts in genomic DNA by high-performance liquid chromatography (HPLC) separation and quantification of nucleosides and (2) methylation-sensitive inter-simple sequence repeat (MS-ISSR) technique. HPLC analysis revealed that the DNA methylation events in male and female spinach leaves markedly decreased upon 30 ?M 5-azaC treatment, and the methylation level gradually decreased with the increase in 5-azaC concentration. To study the altered DNA methylation patterns in spinach after 5-azaC treatment, untreated and 500 ?M 5-azaC-treated samples were analyzed by MS-ISSR assay. A total of 385 informative profiles were resolved using 35 ISSR primer sets. MS-ISSR analysis showed various altered methylation patterns between untreated and 5-azaC-treated spinach plants. These alterations were mainly demethylation events, which were largely consistent with the HPLC results. Both HPLC and MS-ISSR analyses showed that the changes in DNA methylation levels and patterns were similar in male and female spinach leaves, which implies that sex was not the main factor influencing DNA methylation levels and patterns in the vegetative organs of spinach. This study could provide a molecular basis of the altered DNA methylation induced by 5-azaC, and lay a foundation for further investigation of the relationship between methylation and sex determination and development in this dioecious plant spinach. PMID:24556376

  12. Alkaloids as inhibitors of photophosphorylation in spinach chloroplasts.

    PubMed

    Vallejos, R H; Andreo, C S

    1974-01-18

    A group of 12 alkaloids were tested as inhibitors of photophosphorylation in spinach chloroplasts. Ajmaline, a dihydroindole alkaloid, was found to be the strongest inhibitor of both cyclic and non-cyclic photophosphorylation. Low concentrations of ajmaline also inhibited the dark and light ATPases, and the coupled electron flow from water to ferricyanide, measured either as ferrocyanide formed or as oxygen evolved, but not the uncoupled electron transport or the pH rise of illuminated unbuffered suspensions of chloroplasts. Higher concentrations of ajmaline stimulated, instead of inhibiting, photosynthetic electron transport or oxygen evolution and decreased the pH rise, thus behaving as an uncoupler, such as ammonia. Photophosphorylation was partially inhibited by 100 microM dihydrosanguinarine, 100 microM dihydrochelerythrine (benzophenanthridine alkaloids); 500 microM O,O'-dimethylmagnoflorine, 500 microM N-methylcorydine (aporphine alkaloids) and 1 mM julocrotine. They also inhibited coupled oxygen evolution and only partially (dihydrosanguinarine and dihydrochelerythrine) or not at all (the other alkaloids) uncoupled oxygen evolution. Spegazzinine (dihydroindole alkaloid), magnoflorine, N-methylisocorydine, coryneine (aporphine alkaloids), candicine and ribalinium chloride were without effect on photophosphorylation at 500 microM. PMID:19397001

  13. Purification and Properties of Glutamine Synthetase from Spinach Leaves

    PubMed Central

    Ericson, Mary C.

    1985-01-01

    The chloroplastic glutamine synthetase of spinach leaves has been purified to homogeneity using affinity chromatography. This involves a tandem `reactive blue A-agarose' and `reactive red-A-agarose' as the final step in the procedure. This procedure results in a yield of 18 milligrams of pure glutamine synthetase per kilogram of starting material. The purity of our enzyme has been demonstrated on both one- and two-dimensional polyacrylamide gels. Purified glutamine synthetase has a molecular weight of 360,000 daltons and consists of eight 44,000 dalton subunits. The Km is 6.7 millimolar for glutamate, 1.8 millimolar for ATP (synthetase assay), and 37.6 millimolar for glutamine (transferase assay). The isoelectric point is 6.5 and the pH optima are 7.3 in the synthetase assay and 6.4 in the transferase assay. The irreversible, competitive inhibitors methionine sulfoxamine and phosphinothricin have Ki values of 0.1 millimolar and 6.1 micromolar, respectively. Amino acid analysis has been carried out and the results compared with published analyses for other isoforms of glutamine synthetase. Images Fig. 1 PMID:16664546

  14. Effect of electrolyzed water for reduction of foodborne pathogens on lettuce and spinach.

    PubMed

    Park, E J; Alexander, E; Taylor, G A; Costa, R; Kang, D H

    2008-08-01

    The ability of electrolyzed water (EW) to inactivate foodborne pathogens on the surfaces of lettuce and spinach was investigated. Lettuce and spinach leaves were inoculated with a cocktail of 3 strains each of Escherichia col O157:H7, Salmnonella Typhimurium, and Listeria monocytogenes and treated with acidic electrolyzed water (AC-EW), alkaline electrolyzed water (AK-EW), alkaline electrolyzed water followed by acidic electrolyzed water (sequential treatment, AK-EW + AC-EW), deionized water followed by acidic electrolyzed water (sequential treatment, DW + AC-EW), and deionized water (control, DW) for 15, 30 s, and 1, 3, and 5 min at room temperature (22 +/- 2 degrees C). For all 3 pathogens, the same pattern of microbial reduction on lettuce and spinach were apparent. The relative efficacy of reduction was AC-EW > DW + AC-EW approximately = AK-EW + AC-EW > AK-EW > control. After a 3-min treatment of AC-EW, the 3 tested pathogens were reduced below the detection limit (0.7 log). DW + AC-EW and AK-EW + AC-EW produced the same levels of reduction after 5 min when compared to the control. AK-EW did not reduce levels of pathogens even after a 5-min treatment on lettuce and spinach. Results suggest that AC-EW treatment was able to significantly reduce populations of the 3 tested pathogens from the surfaces of lettuce and spinach with increasing time of exposure. PMID:19241556

  15. Effects of conventional and organic fertilization on spinach ( Spinacea oleracea L.) growth, yield, vitamin C and nitrate concentration during two successive seasons

    Microsoft Academic Search

    Sedat Citak; Sahriye Sonmez

    2010-01-01

    Current experiment was laid out in order to compare different kinds of organic manure and chemical fertilizer application in growing spinach under the open-field conditions in two successive seasons. Matador type spinach (Spinacea oleracea L.) was cultivated organically and conventionally and spinach growth, yield, vitamin C and nitrate concentrations were checked throughout two successive seasons (autumn and winter). Commercial chemical

  16. Mineral balances of human subjects consuming spinach in a low-fiber diet and in a diet containing fruits and vegetables1'2

    Microsoft Academic Search

    June L Kelsay; Elizabeth S Prather

    The effects of spinach in the diet on mineral balances were examined in 12 men who consumed three controlled diets for 4 wk each. Diet 1, a low-fiber diet, contained spinach, which is high in oxalic acid, every other day. Diet 2 contained fiber in fruits and vegetables, including spinach every other day. Diet 3 was the same as diet

  17. Ultrasound enhanced sanitizer efficacy in reduction of Escherichia coli O157:H7 population on spinach leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of ultrasound to enhance the efficacy of selected sanitizers in reduction of Escherichia coli O157:H7 populations on spinach was investigated. Spot-inoculated spinach samples were treated with water, chlorine, acidified sodium chlorite (ASC), peroxyacetic acid (POAA), and acidic electrolyzed...

  18. Colonization of spinach by Verticillium dahliae and effects of pathogen localization on the efficacy of seed treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is caused by the soilborne fungus V. dahliae on spinach (Spinacia oleracea L.) but the disease is a serious problem only in seed production fields. Spinach crops are harvested well before symptom expression, and thus, Verticillium wilt is not a significant threat in fresh and proc...

  19. THE EFFECTS OF ELECTRON BEAM IRRADIATION AND SANITIZERS IN THE REDUCTION OF PATHOGENS AND ATTACHMENT PREVENTION ON SPINACH

    E-print Network

    Neal, Jack A.

    2010-07-14

    The effects of electron beam (e-beam) irradiation and sanitizers in the reduction of Escherichia coli O157:H7 and Salmonella counts and attachment prevention on spinach was studied. Survival of these pathogens in spinach was observed at multiple...

  20. An Improved Method for the Extraction and Thin-Layer Chromatography of Chlorophyll A and B from Spinach

    ERIC Educational Resources Information Center

    Quach, Hao T.; Steeper, Robert L.; Griffin, William G.

    2004-01-01

    A simple and fast method, which resolves chlorophyll a and b from spinach leaves on analytical plates while minimizing the appearance of chlorophyll degradation products is shown. An improved mobile phase for the Thin-layer chromatographic analysis of spinach extract that allows for the complete resolution of the common plant pigments found in…

  1. Quality of fresh-cut iceberg lettuce and spinach irradiated at doses up to 4kGy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to investigate radiation tolerance of fresh-cut Iceberg lettuce and spinach. Fresh-cut Iceberg lettuce packaged in modified atmosphere packages and spinach in perforated film bags were irradiated with gamma rays at doses of 0, 1, 2, 3, and 4 kGy. After irradiation, the sam...

  2. Natural Selection: 2006 E. coli Recall of Fresh Spinach A Case Study by The Food Industry Center

    E-print Network

    Weiblen, George D

    also helps illustrate the complexity of the food supply chain and the food recall process. A similar1 Natural Selection: 2006 E. coli Recall of Fresh Spinach A Case Study by The Food Industry Center. While every food recall is important and unique, the contamination of fresh spinach with the bacteria

  3. Characterization of a Photosynthesizing Reconstituted Spinach Chloroplast Preparation 1

    PubMed Central

    Kow, Yoke Wah; Gibbs, Martin

    1982-01-01

    A particulate preparation (MgP) capable of photosynthetic CO2 assimilation without the addition of stromal protein was obtained by rupturing whole spinach (Spinacia oleracea var. America) chloroplasts in 15 millimolar MgCl2 buffered with Tricine at pH 8.5. This CO2 assimilation was dependent upon light, inorganic phosphate, ferredoxin, ADP, NAD or NADP, and primer. Excepting glycolate, the products of CO2 fixation by MgP were similar to those found with whole chloroplasts. Glycerate-3-phosphate (PGA), fructose-1, 6-bisphosphate (FBP), and ribose-5-phosphate (R5P) but not fructose-6-P (F6P) functioned as primers. Concentrations of PGA and FBP but not of R5P higher than 2 millimolar were inhibitory to CO2 fixation. A lag of CO2 fixation was observed with PGA and FBP but not with R5P. This lag as well as inhibition by NADP, ADP, and ATP in the FBP-primed preparation was eliminated by an equimolar mixture of FBP plus F6P indicating FBPase as the sensitive site. NADP, ADP, and ATP also blocked CO2 fixation by the PGA-fortified preparation but inhibition was even more sensitive than that observed when FBP was added. Inhibition by AMP in the PGA and FBP-primed preparations was not affected by the addition of F6P. When R5P was the starting primer, inhibition of CO2 fixation was relatively insensitive to the adenylates and NADP. In contrast to the parent whole chloroplast, CO2 fixation by MgP was insensitive to high (5 millimolar) inorganic phosphate. Depending upon the ferredoxin concentration, NAD was as effective as NADP in supporting CO2 fixation. PMID:16662154

  4. Factors affecting the quality of freeze-dried and compressed spinach 

    E-print Network

    Wisakowsky, Eugene Edward

    1975-01-01

    the soluble and insoluble form. Color of spinach in the final product is most dependent on the blanching used. Cruess(1958), as a result of a classic piece of research, suggested using 170'F (77'C) for 7 minutes because of the low conver sion... and the third for reconstituted spinach. which had been cooked and freeze-dried. The fresh samples, used for determination of color and texture were randomly drawn, sealed in 4303 cans to minimize desication, and stored at 35'F for approximately 8 hours...

  5. Effects of blue light deficiency on acclimation of light energy partitioning in PSII and CO2 assimilation capacity to high irradiance in spinach leaves.

    PubMed

    Matsuda, Ryo; Ohashi-Kaneko, Keiko; Fujiwara, Kazuhiro; Kurata, Kenji

    2008-04-01

    Blue light effects on the acclimation of energy partitioning characteristics in PSII and CO2 assimilation capacity in spinach to high growth irradiance were investigated. Plants were grown hydroponically in different light treatments that were a combination of two light qualities and two irradiances,i.e. white light and blue-deficient light at photosynthetic photon flux densities (PPFDs) of 100 and 500 micromol m(-2) s(-1). The CO2 assimilation rate, the quantum efficiency of PSII(PhiPSII) and thermal dissipation activity (F(v)/F(m)-F'(v)/F'(m)) in young, fully expanded leaves were measured under 1,600 micromol m(-2) s(-1) white light. The CO2 assimilation rate and (PhiPSII) were higher, while F(v)/F(m)-F'(v)/F'(m) was lower in plants grown under high irradiance than in plants grown under low irradiance. These responses were observed irrespective of the presence or absence of blue light during growth. The extent of the increase in the CO2 assimilation rate and PhiPSII and the decrease in F(v)/F(m)-F'(v)/F'(m) by high growth irradiance was smaller under blue light-deficient conditions. These results indicate that blue light helps to boost the acclimation responses of energy partitioning in PSII and CO2 assimilation to high irradiance. Similarly, leaf N, Cyt f and Chl contents per unit leaf area increased by high growth irradiance, and the extent of the increment in leaf N, Cyt f and Chl was smaller under blue light-deficient conditions. Regression analysis showed that the differences in energy partitioning in PSIIand CO2 assimilation between plants grown under high white light and high blue-deficient light were closely related to the difference in leaf N. PMID:18349045

  6. Isolation of a cDNA clone for spinach lipid transfer protein and evidence that the protein is synthesized by the secretory pathway

    SciTech Connect

    Bernhard, W.R.; Thoma, S.; Botella, J.; Somerville, C.R. (Michigan State Univ., East Lansing (United States))

    1991-01-01

    A cDNA clone encoding a nonspecific lipid transfer protein from spinach (Spinacia oleracea) was isolated by probing a library with synthetic oligonucleotides based on the amino acid sequence of the protein. Determination of the DNA sequence indicated a 354-nucleotide open reading frame which encodes a 118-amino acid residue polypeptide. The first 26 amino acids of the open reading frame, which are not present in the mature protein, have all the characteristics of a signal sequence which is normally associated with the synthesis of membrane proteins or secreted proteins. In vitro transcription of the cDNA and translation in the presence of canine pancreatic microsomes or microsomes from cultured maize endosperm cells indicated that proteolytic processing of the preprotein to the mature form was associated with cotranslational insertion into the microsomal membranes. Because there is no known mechanism by which the polypeptide could be transferred from the microsomal membranes to the cytoplasm, the proposed role of this protein in catalyzing lipid transfer between intracellular membranes is in doubt. Although the lipid transfer protein is one of the most abundant proteins in leaf cells, the results of genomic Southern analysis were consistent with the presence of only one gene. Analysis of the level of mRNA by Northern blotting indicated that the transcript was several-fold more abundant than an actin transcript in leaf and petiole tissue, but was present in roots at less than 1% of the level in petioles.

  7. Kinetic properties of monogalactosyldiacylglycerol synthase from spinach chloroplast envelope membranes.

    PubMed

    Maréchal, E; Block, M A; Joyard, J; Douce, R

    1994-02-25

    We have investigated the functioning of monogalactosyldiacylglycerol (MGDG) synthase activity partially purified from spinach chloroplast envelope membranes, using mixed micelles containing diacylglycerol (the substrate for MGDG synthase), CHAPS (3-[(cholamidopropyl)dimethylammonio]-1- propanesulfonic acid), and phosphatidylglycerol. The presence of this anionic phospholipid was essential for optimal MGDG synthase activity because it strongly improves diacylglycerol solubilization by CHAPS. We have demonstrated that the "surface dilution" kinetic model proposed by Deems et al. (Deems, R.A., Eaton, B.R., and Dennis, E.A. (1975) J. Biol. Chem. 250, 9013-9020) is valid for MGDG synthase assayed in mixed micelles within a narrow range of CHAPS concentration. However, the experimental conditions we have set up in this study led to the description of defined equilibrium and kinetic parameters of the interaction of the envelope MGDG synthase with diacylglycerol. Two-substrate kinetic studies were performed with varied UDP-galactose molar concentrations and varied dioleoylglycerol surface concentrations. The families of reciprocal plots obtained were shown to intersect at a single point of the 1/[substrate] axis thus demonstrating that MGDG synthase is a sequential, either random or ordered, bireactant system. Therefore, MGDG synthase possesses two distinct and independent substrate-binding sites, a hydrophilic one for UDP-galactose and a hydrophobic one for diacylglycerol. The dependence of kinetic parameters on the diacylglycerol mol fraction allows a comparison of the affinity of the enzyme for a wide range of diacylglycerol molecular species. The Km values obtained were ranging between 0.0089 mol fraction (52 microM) for dilinoleoylglycerol (18:2/18:2) to 0.0666 mol fraction (416 microM) for distearoylglycerol (18:0/18:0), but the differences observed were not really related to the unsaturation of the molecule since the Km value for dilinoleoylglycerol was much lower than that (0.040 mol fraction) for dilinoleoylglycerol (18:3/18:3). The Km values for dioleoylglycerol (18:1/18:1) and for the diacylglycerol molecular species synthesized within chloroplasts, i.e. containing 18:1/16:0, were in the average range, i.e. lower than 0.030 mol fraction (around 170 microM). PMID:8119920

  8. Potential anticancer effect of red spinach (Amaranthus gangeticus) extract.

    PubMed

    Sani, Huzaimah Abdullah; Rahmat, Asmah; Ismail, Maznah; Rosli, Rozita; Endrini, Susi

    2004-01-01

    The objective of this study was to determine the anti cancer effects of red spinach (Amaranthus gangeticus Linn) in vitro and in vivo. For in vitro study, microtitration cytotoxic assay was done using 3-(4,5-dimethylthiazol-2-il)-2,5-diphenil tetrazolium bromide (MTT) kit assay. Results showed that aqueous extract of A gangeticus inhibited the proliferation of liver cancer cell line (HepG2) and breast cancer cell line (MCF-7). The IC(50) values were 93.8 mu g/ml and 98.8 mu g/ml for HepG2 and MCF-7, respectively. The inhibitory effect was also observed in colon cancer cell line (Caco-2), but a lower percentage compared to HepG2 and MCF-7. For normal cell line (Chang Liver), there was no inhibitory effect. In the in vivo study, hepatocarcinogenesis was monitored in rats according to Solt and Farber (1976) without partial hepatectomy. Assay of tumour marker enzymes such as glutathione S-transferase (GST), gamma-glutamyl transpeptidase (GGT), uridyl diphosphoglucuronyl transferase (UDPGT) and alkaline phosphatase (ALP) were carried out to determine the severity of hepatocarcinogenesis. The result found that supplementation of 5%, 7.5% and 10% of A. gangeticus aqueous extract to normal rats did not show any significant difference towards normal control (P <0.05). The exposure of the rats to chemical carcinogens diethylnitrosamine (DEN) and 2-acetylaminofluorene (AAF) showed a significant increase in specific enzyme activity of GGT, GST, UDPGT and ALP compared to normal control (P <0.05). However, it was found that the supplementation of A. gangeticus aqueous extract in 5%, 7.5% and 10% to cancer-induced rats could inhibit the activity of all tumour marker enzymes especially at 10% (P <0.05). Supplementation of anti cancer drug glycyrrhizin at suggested dose (0.005%) did not show any suppressive effect towards cancer control (P <0.05). In conclusion, A. gangeticus showed anticancer potential in in vitro and in vivo studies. PMID:15563447

  9. Polycations Globally Enhance Binding of 14-3-3 omega to Target Proteins in Spinach Leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The binding of 14-3-3' to phosphorylated NR (pNR) is stimulated by cations such as Mg2+ or spermine, and decreased by 5'-AMP. In order to determine whether binding to other cellular proteins is affected similarly, Far-Western overlays of extracts prepared from light- or dark-treated spinach (Spinac...

  10. Multispectral fluorescence imaging for detection of bovine feces on Romaine lettuce and baby spinach leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral fluorescence imaging with ultraviolet-A excitation was used to evaluate the feasibility of two-waveband fluorescence algorithms for the detection of bovine fecal contaminants on the abaxial and adaxial surfaces of Romaine lettuce and baby spinach leaves. Correlation analysis was used t...

  11. Persistence of enterohemorrhagic and non-pathogenic E. coli on spinach leaves and in rhizosphere

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Outbreaks associated with leafy greens have focused attention on the persistence of Escherichia coli O157:H7 on produce. Ecological interactions of E. coli O157:H7 and spinach require detailed characterization. Purpose: Survival of E. coli O157:H7 and non-pathogenic E. coli was evalua...

  12. Persistence of enterohemorrhagic and non-pathogenic E. coli on spinach leaves and in rhizosphere soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foodborne illness outbreaks associated with leafy greens have raised concerns about the persistence of Escherichia coli O157:H7 on fresh produce and in the cropping environment. The set of characteristics that enable the enteric bacterium E. coli O157:H7 to survive on undamaged spinach leaves, roots...

  13. Perchlorate uptake in spinach as related to perchlorate, nitrate and chloride concentrations in irrigation water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several studies have reported on the detection of perchlorate in edible leafy vegetables irrigated with Colorado River water. However, there is no information on spinach as related to perchlorate in irrigation water nor on the effect of other anions on perchlorate uptake. A greenhouse perchlorate up...

  14. Laser Activation of Rapid Absorption Changes in Spinach Chloroplasts and Chlorella 1

    PubMed Central

    Hildreth, W. W.; Avron, M.; Chance, B.

    1966-01-01

    The kinetics of the 520 m? absorption change in spinach chloroplasts and Chlorella vulgaris following a flash from the ruby laser have been determined as follows: rise halftime ? 0.3 × 10?6 second; rapid recovery halftime = 5 to 6 × 10?6 second; intermediate recovery halftime = 4 × 10?4 second (spinach chloroplasts only); slow recovery halftime = 12 to 170 × 10?3 second, dependent on the measuring light intensity and aerobicity of the suspension. The rapid phase of the 520 m? reaction is approximately independent of temperature, from 295° to 77° Absolute. With increasing oxygenation of the sample, the extent of the rapid phase decreases, the extent of the slow phase increases, while the extent of the intermediate phase in spinach chloroplasts remains constant. In spinach chloroplasts, no recovery halftime of the 3 recovery phases for the 520 m? absorption change was observed to correspond to the halftime for oxidation of cytochrome f (t½ = 1.3 × 10?3 second). PMID:16656366

  15. Biofilm formation and bacteriophage inactivation of Escherichia coli O157:H7 on spinach harvester blades

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Outbreaks associated with leafy greens have focused attention on the transfer of human pathogens to leafy greens during harvest with commercial equipment. The role of this equipment should be investigated to develop mitigation strategies. Biofilm formation by Escherichia coli O157:H7 on a spinach ha...

  16. Survival of Salmonella on spinach leaves treated with contaminated irrigation water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Salmonella outbreaks have been associated with the consumption of fresh produce. The produce may be contaminated with Salmonella during on-farm contact with contaminated water. Transmission of Salmonella from contaminated irrigation water to spinach plants in growth chamber settings ...

  17. [Effect of cooking on content of nitrates, vitamin C, magnesium and iron in spinach].

    PubMed

    Astier-Dumas, M

    1975-01-01

    Cooking is known to lower the mineral and vitaminic content of foodstuffs. Recently, contaminant became to be a problem in foods, and it was proposed to use blanching or boiling to diminish contaminant residues in foods, specially vegetables. An example of this attitude is given by the use of blanching to lower nitrates levels in spinach specially prepared for baby foods. PMID:1211733

  18. 24-epibrassinolide and 20-hydroxyecdysone affect photosynthesis differently in maize and spinach.

    PubMed

    Rothová, Olga; Holá, Dana; Ko?ová, Marie; T?mová, Lenka; Hnili?ka, František; Hnili?ková, Helena; Kamlar, Marek; Macek, Tomáš

    2014-07-01

    The aim of the work was to examine the effect of brassinosteroid (24-epibrassinolide; 24E) and ecdysteroid (20-hydroxyecdysone; 20E) on various parts of primary photosynthetic processes in maize and spinach. Additionally, the effect of steroids on gaseous exchange, pigment content and biomass accumulation was studied. The efficiency of the photosynthetic whole electron-transport chain responded negatively to the 24E or 20E treatment in both species, but there were interspecific differences regarding Photosystem (PS) II response. A positive effect on its oxygen-evolving complex and a slightly better energetical connectivity between PSII units were observed in maize whereas the opposite was true for spinach. The size of the pool of the PSI end electron acceptors was usually diminished due to 24E or 20E treatment. The treatment of plants with 24E or 20E applied individually positively influenced the content of photosynthetic pigments in maize (not in spinach). On the other hand, it did not affect gaseous exchange in maize but resulted in its reduction in spinach. Plants treated with combination of both steroids mostly did not significantly differ from the control plants. We have demonstrated for the first time that 20E applied in low (10nM) concentration can affect various parts of photosynthetic processes similarly to 24E and that brassinosteroids regulate not only PSII but also other parts of the photosynthetic electron transport chain - but not necessarily in the same way. PMID:24769061

  19. LEAF MARGIN INFLORESCENCE

    E-print Network

    Holland, Jeffrey

    { LEAF BLADE LEAF MARGIN PETIOLE INFLORESCENCE WS-27-W Guidelines for Submitting Digital Plant RAGWEED VELVETLEAF Leaf arrangement on the plant stem. Alternate Opposite Alternate CANADA THISTLE COMMON RAGWEED VELVETLEAF Leaf attachment to the plant stem. Sessile Petiole Petiole CANADA THISTLE COMMON

  20. Generic Escherichia coli Contamination of Spinach at the Preharvest Stage: Effects of Farm Management and Environmental Factors

    PubMed Central

    Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Jun, Mikyoung; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Ivanek, Renata

    2013-01-01

    The objective of this study was to determine the effects of farm management and environmental factors on preharvest spinach contamination with generic Escherichia coli as an indicator of fecal contamination. A repeated cross-sectional study was conducted by visiting spinach farms up to four times per growing season over a period of 2 years (2010 to 2011). Spinach samples (n = 955) were collected from 12 spinach farms in Colorado and Texas as representative states of the Western and Southwestern United States, respectively. During each farm visit, farmers were surveyed about farm-related management and environmental factors using a questionnaire. Associations between the prevalence of generic E. coli in spinach and farm-related factors were assessed by using a multivariable logistic regression model including random effects for farm and farm visit. Overall, 6.6% of spinach samples were positive for generic E. coli. Significant risk factors for spinach contamination with generic E. coli were the proximity (within 10 miles) of a poultry farm, the use of pond water for irrigation, a >66-day period since the planting of spinach, farming on fields previously used for grazing, the production of hay before spinach planting, and the farm location in the Southwestern United States. Contamination with generic E. coli was significantly reduced with an irrigation lapse time of >5 days as well as by several factors related to field workers, including the use of portable toilets, training to use portable toilets, and the use of hand-washing stations. To our knowledge, this is the first report of an association between field workers' personal hygiene and produce contamination with generic E. coli at the preharvest level. Collectively, our findings support that practice of good personal hygiene and other good farm management practices may reduce produce contamination with generic E. coli at the preharvest level. PMID:23666336

  1. Leaf Modeling and Constrained Leaf Morphing in Leaf Space Saurabh Garg1

    E-print Network

    Leow, Wee Kheng

    Leaf Modeling and Constrained Leaf Morphing in Leaf Space Saurabh Garg1 , Leow Wee Kheng1 1 School@comp.nus.edu.sg Morphing from an elliptic leaf (first row, first image) to a deltoid leaf (second row, last image) with a constraint of a leaf with both basal and apical extension (second row, first image). Abstract Leaf modeling

  2. Flavonoid content and antioxidant capacity of spinach genotypes determined by high-performance liquid chromatography/mass spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flavonoids in different spinach genotypes were separated, identified, and quantified by a high-performance liquid chromatographic method with photodiode array and mass spectrometric detection. The antioxidant capacities of the genotypes were also measured using two antioxidant assays - oxygen radica...

  3. IN VITRO BINDING OF BILE ACIDS BY SPINACH, KALE, BRUSSEL SPROUTS, BROCCOLI, MUSTARD GREENS, GREEN BELL PEPPER, CABBAGE AND COLLARDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The in vitro binding of bile acids by spinach (spinacia oleracea), kale (brassica oleracea acephala), brussels sprouts (brassica oleracea gemmifera), broccoli (brassica oleracea italica), mustard greens (brassica juncea), peppers green (capsicum annuum), cabbage (brassica oleracea capitala) and coll...

  4. Effect of chemical sanitizer combined with modified atmosphere packaging on inhibiting Escherichia coli O157:H7 in commercial spinach

    Microsoft Academic Search

    Sun-Young Lee; Seung-Youb Baek

    2008-01-01

    Escherichia coli O157:H7 contaminated spinach has recently caused several outbreaks of human illness in the USA and Canada. However, to date, there has been no study demonstrating an effective way to eliminate E. coli O157:H7 in spinach. Therefore, this study was conducted to investigate the effect of chemical sanitizers alone or in combination with packaging methods such as vacuum and

  5. Element contents and food safety of water spinach ( Ipomoea aquatica Forssk.) cultivated with wastewater in Hanoi, Vietnam

    Microsoft Academic Search

    Helle Marcussen; Karin Joergensen; Peter E. Holm; Daniela Brocca; Robert W. Simmons; Anders Dalsgaard

    2008-01-01

    Extensive aquatic or semi-aquatic production of water spinach (Ipomoea aquatica Forssk.) for human consumption takes place in Southeast Asia. The aim of this study was to assess the concentrations of 38\\u000a elements in soil and water spinach cultivated under different degrees of wastewater exposure in Hanoi, Vietnam. The results\\u000a showed no effect of wastewater use on the overall element concentrations

  6. Elm Leaf Beetle

    E-print Network

    Patrick, Carl D.

    2002-05-22

    Elm leaf beetles damage all varieties of elm trees. Learn how to identify this insect and understand its biology and life cycle. There are suggestions for controlling elm leaf beetles, as well as a table of insecticides effective against...

  7. Rapid induction of frost hardiness in spinach seedlings under salt stress

    Microsoft Academic Search

    Dirk K. Hincha

    1994-01-01

    The frost hardiness of many plant species can be increased by exposing plants to low, non-freezing temperatures. It has been shown that at least in some herbaceous mono- and dicotyledonous species, hardening can also be induced by treating plants with NaCl at otherwise non-hardening temperatures. In the present investigation, the roots of approximately six-week-old spinach (Spinacia oleracea L.) seedlings were

  8. Influence of phosphate and nitrate supply on root hair formation of rape, spinach and tomato plants

    Microsoft Academic Search

    Doris Foehse; A. Jungk

    1983-01-01

    Summary Experiments with tomato, rape and spinach in nutrient solutions have shown that the formation of root hairs is strongly influenced by phosphate and nitrate supply. Decreasing the phosphate concentration of the nutrient solution from 100 to 2 ?M P resulted in an increase of root hair length from 0.1–0.2 to 0.7 mm of the three plant species. Root hair

  9. Influences of Lead (II) Chloride on the Nitrogen Metabolism of Spinach

    Microsoft Academic Search

    Wu Xiao; Liu Chao; Qu Chunxiang; Huang Hao; Liu Xiaoqing; Chen Liang; Su Mingyu; Hong Fashui

    2008-01-01

    Lead (Pb2+) is a well-known highly toxic element. The mechanisms of the Pb2+ toxicity are not well understood for nitrogen metabolism of higher plants. In this paper, we studied the effects of various\\u000a concentrations of PbCl2 on the nitrogen metabolism of growing spinach. The experimental results showed that Pb2+ treatments significantly decreased the nitrate nitrogen $$\\\\left( {{\\\\text{NO}}_3^{\\\\,\\\\, - } -

  10. Comparison of ribosomal proteins of chloroplast from Spinach and of E. coli

    Microsoft Academic Search

    A. M. Dorne; J. Eneas-Filho; P. Heizmann; R. Mache

    1984-01-01

    A comparison of ribosomal proteins from Escherichia coli and from chloroplasts of Spinach was made using two separate methods: electrophoretic migration and immunochemical cross-reaction between blotted E. coli ribosomal proteins and chloroplast ribosomal subunits antisera. It is shown that L2 from E. coli (E-12) and L4 from chloroplasts (CS-L4) comigrated and that E-L4 immunologically cross-reacted with the isolated CS-L4 antibody.

  11. Phenolic Constituents of Celosia cristata L. Susceptible to Spinach Root Rot Pathogen Aphanomyces cochlioides

    Microsoft Academic Search

    Yaolin WEN; Satoshi TAHARA

    2006-01-01

    Aphanomyces cochlioides is a soil-borne phytopatho- genic Peronosporomycete which is responsible for the root rot disease of spinach (Spinacia oleracea L.) and damping-off disease of sugar beet (Beta vulgaris var. rapa Dum.). The presence of the potent zoospore attractant, cochliophilin A (5-hydroxy-6,7-methylene- dioxyflavone, 1), has been confirmed in a range of host plants in the Chenopodiaceae including sugar beet, 1)

  12. Interactions between Food-Borne Pathogens and Protozoa Isolated from Lettuce and Spinach?

    PubMed Central

    Gourabathini, Poornima; Brandl, Maria T.; Redding, Katherine S.; Gunderson, John H.; Berk, Sharon G.

    2008-01-01

    The survival of Salmonella enterica was recently shown to increase when the bacteria were sequestered in expelled food vacuoles (vesicles) of Tetrahymena. Because fresh produce is increasingly linked to outbreaks of enteric illness, the present investigation aimed to determine the prevalence of protozoa on spinach and lettuce and to examine their interactions with S. enterica, Escherichia coli O157:H7, and Listeria monocytogenes. Glaucoma sp., Colpoda steinii, and Acanthamoeba palestinensis were cultured from store-bought spinach and lettuce and used in our study. A strain of Tetrahymena pyriformis previously isolated from spinach and a soil-borne Tetrahymena sp. were also used. Washed protozoa were allowed to graze on green fluorescent protein- or red fluorescent protein-labeled enteric pathogens. Significant differences in interactions among the various protist-enteric pathogen combinations were observed. Vesicles were produced by Glaucoma with all of the bacterial strains, although L. monocytogenes resulted in the smallest number per ciliate. Vesicle production was observed also during grazing of Tetrahymena on E. coli O157:H7 and S. enterica but not during grazing on L. monocytogenes, in vitro and on leaves. All vesicles contained intact fluorescing bacteria. In contrast, C. steinii and the amoeba did not produce vesicles from any of the enteric pathogens, nor were pathogens trapped within their cysts. Studies of the fate of E. coli O157:H7 in expelled vesicles revealed that by 4 h after addition of spinach extract, the bacteria multiplied and escaped the vesicles. The presence of protozoa on leafy vegetables and their sequestration of enteric bacteria in vesicles indicate that they may play an important role in the ecology of human pathogens on produce. PMID:18310421

  13. Expression and localization of FAD2 desaturase from spinach in tobacco cells

    Microsoft Academic Search

    R. Todorova

    2008-01-01

    The sites of desaturation in plant cells were studied by expressing the fusion gene composed of the genes encoding FAD2 (?12\\u000a desaturase) from spinach (Spinacia oleracea) and enhanced green fluorescent protein (EGFP) under the control of the 35S cauliflower mosaic virus promoter. The chimeric\\u000a protein was functional in tobacco (Nicotiana tabacum) BY-2 cells. The temporal changes in distribution and localization

  14. Activation of spinach pullulanase by reduction results in a decrease in the number of isomeric forms

    Microsoft Academic Search

    Ilka Schindler; Andreas Renz; Franz X Schmid; Erwin Beck

    2001-01-01

    Spinach starch debranching enzyme, a limit dextrinase or pullulanase (EC 3.2.1.41), is a monomeric protein of 100 kDa that produces up to seven coexisting and mutually interconvertible isomers of different specific activity, a phenomenon that has been termed microheterogeneity and for which a structural explanation has not yet been presented. The enzyme can be activated by reduction, in particular by

  15. Analysis of cis -acting DNA elements mediating induction and repression of the spinach nitrite reductase gene

    Microsoft Academic Search

    Sobhana Sivasankar; Rajeev Rastogi; Lisa Jackman; Ann Oaks; Steven Rothstein

    1998-01-01

    .   The expression of nitrite reductase (NiR; EC 1.7.7.1), the second enzyme in the nitrate assimilatory pathway, is regulated\\u000a by nitrate as well as by end-products of nitrate assimilation, namely, glutamine (Gln) and asparagine (Asn). Nitrate induces\\u000a expression of the NiR gene. Previously, using deletion analysis of the spinach (Spinacia oleracea L.) NiR gene promoter in transgenic tobacco (Nicotiana tabacum

  16. Modelling Heterogeneous DSP-FPGA Based System Partitioning with Extensions to the Spinach Simulation Environment

    Microsoft Academic Search

    Michael Brogioli; Joseph Cavallaro

    2005-01-01

    In this paper we present system-on-a-chip exten- sions to the Spinach simulation environment for rapidly prototyp- ing heterogeneous DSP\\/FPGA based architectures, specifically in the embedded domain. This infrastructure has been successfully used to model systems varying from multiprocessor gigabit ethernet controllers to Texas Instruments C6x series DSP based systems with tightly coupled FPGA based coprocessors for com- putational offloading. As

  17. Changes in Activities of Enzymes of Carbon Metabolism in Leaves during Exposure of Plants to Low Temperature 1

    PubMed Central

    Holaday, A. Scott; Martindale, Wayne; Alred, Rhu; Brooks, Andrew L.; Leegood, Richard C.

    1992-01-01

    The aim of this study was to determine the response of photosynthetic carbon metabolism in spinach and bean to low temperature. (a) Exposure of warm-grown spinach and bean plants to 10°C for 10 days resulted in increases in the total activities of a number of enzymes, including ribulose 1,5-bisphosphate carboxylase (Rubisco), stromal fructose 1,6 bisphosphatase (Fru 1,6-P2ase), sedoheptulose 1,7-bisphosphatase (Sed 1,7-P2ase), and the cytosolic Fru 1,6-P2ase. In spinach, but not bean, there was an increase in the total activity of sucrose-phosphate synthase. (b) The CO2-saturated rates of photosynthesis for the cold-acclimated spinach plants were 68% greater at 10°C than those for warm-acclimated plants, whereas in bean, rates of photosynthesis at 10°C were very low after exposure to low temperature. (c) When spinach leaf discs were transferred from 27 to 10°C, the stromal Fru 1,6-P2ase and NADP-malate dehydrogenase were almost fully activated within 8 minutes, and Rubisco reached 90% of full activation within 15 minutes of transfer. An initial restriction of Calvin cycle fluxes was evident as an increase in the amounts of ribulose 1,5-bisphosphate, glycerate-3-phosphate, Fru 1,6-P2, and Sed 1,7-P2. In bean, activation of stromal Fru 1,6-P2ase was weak, whereas the activation state of Rubisco decreased during the first few minutes after transfer to low temperature. However, NADP-malate dehydrogenase became almost fully activated, showing that no loss of the capacity for reductive activation occurred. (d) Temperature compensation in spinach evidently involves increases in the capacities of a range of enzymes, achieved in the short term by an increase in activation state, whereas long-term acclimation is achieved by an increase in the maximum activities of enzymes. The inability of bean to activate fully certain Calvin cycle enzymes and sucrose-phosphate synthase, or to increase nonphotochemical quenching of chlorophyll fluorescence at 10°C, may be factors contributing to its poor performance at low temperature. PMID:16668733

  18. Employing response surface methodology for the optimization of ultrasound assisted extraction of lutein and ?-carotene from spinach.

    PubMed

    Altemimi, Ammar; Lightfoot, David A; Kinsel, Mary; Watson, Dennis G

    2015-01-01

    The extraction of lutein and ?-carotene from spinach (Spinacia oleracea L.) leaves is important to the dietary supplement industry. A Box-Behnken design and response surface methodology (RSM) were used to investigate the effect of process variables on the ultrasound-assisted extraction (UAE) of lutein and ?-carotene from spinach. Three independent variables, extraction temperature (°C), extraction power (%) and extraction time (min) were studied. Thin-layer chromatography (TLC) followed by UV visualization and densitometry was used as a simple and rapid method for both identification and quantification of lutein and ?-carotene during UAE. Methanol extracts of leaves from spinach and authentic standards of lutein and ?-carotene were separated by normal-phase TLC with ethyl acetate-acetone (5:4 (v/v)) as the mobile phase. In this study, the combination of TLC, densitometry, and Box-Behnken with RSM methods were effective for the quantitative analysis of lutein and ?-carotene from spinach extracts. The resulting quadratic polynomial models for optimizing lutein and ?-carotene from spinach had high coefficients of determination of 0.96 and 0.94, respectively. The optimal UAE settings for output of lutein and ?-carotene simultaneously from spinach extracts were an extraction temperature of 40 °C, extraction power of 40% (28 W/cm3) and extraction time of 16 min. The identity and purity of each TLC spot was measured using time-of-flight mass spectrometry. Therefore, UAE assisted extraction of carotenes from spinach can provide a source of lutein and ?-carotene for the dietary supplement industry. PMID:25875040

  19. Decrease in Leaf Sucrose Synthesis Leads to Increased Leaf Starch Turnover and Decreased RuBP-limited Photosynthesis But Not Rubisco-limited Photosynthesis in Arabidopsis Null Mutants of SPSA1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    SPS (Sucrose phosphate synthase) isoforms from dicots cluster into families A, B and C. In this study, we investigated the individual effect of null mutations of each of the four SPS genes in Arabidopsis (spsa1, spsa2, spsb and spsc) on photosynthesis and carbon partitioning. Null mutants spsa1 and ...

  20. Retail display conditions of continuous light and dark on the disposition of vitamins in baby-leaf spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Human-health benefits from the consumption of fruits and vegetables are due to the many bioactive compounds in these foods. Many of these compounds are heavily influenced by genetics (i.e. cultivar) and the environment, especially the many pigments and vitamins that can degrade during processing an...

  1. Short Term Acclimation of Spinach to High Temperatures

    PubMed Central

    Weis, Engelbert

    1984-01-01

    Using intact leaves of Spinacia oleracea (L.), reversible temperature-induced changes in chlorophyll fluorescence emitted at room temperature and at 77K were studied. Interpretation of fluorescence at 77K was largely facilitated by developing a new method to minimize reabsorption artifacts (`diluted leaf-powder'). Leaves of plants grown at 15 to 20°C were exposed for several hours to different temperatures. Upon incubation at 35°C in the dark or in the light, the following changes in 77K fluorescence occurred with a half-time of less than 1 hour: (a) the initial fluorescence (F0) of photosystem I increased by 15%, while that one of photosystem II somewhat decreased; (b) although variable fluorescence declined in both photosystems, the decrease in photosystem II (40%) was more severe; (c) the changes were less significant after 480-nanometer excitation light was replaced by 430-nanometer light. The data were interpreted in terms of a reversible, temperature-induced change in thylakoid structure and related change in the distribution of the absorbed energy in favor of photosystem I, at the expense of photosystem II excitation, probably accompanied by an increase in the rate of thermal deactivation of excited states. The considerable decrease in the variable part of room temperature fluorescence gives rise to the suggestion that this transition has lowered the reduction level of plastoquinone, i.e. has increased electron flow through photosystem I, relative to photosystem II. Possible physiological and mechanistic analogies between this temperature-induced state transition and the light-dependent state 1-state 2 regulation has been discussed. PMID:16663430

  2. Effect of electrolyzed oxidizing water treatment on the reduction of nitrite levels in fresh spinach during storage.

    PubMed

    Hao, Jianxiong; Li, Huiying; Wan, Yangfang; Liu, Haijie

    2015-03-01

    Leafy vegetables are the major source of nitrite intake in the human diet, and technological processing to control nitrite levels in harvested vegetables is necessary. In the current work, the effect of electrolyzed oxidizing water (EOW) on the nitrite and nitrate levels in fresh spinach during storage was studied. EOW treatment, including slightly acidic electrolyzed water and acidic electrolyzed water, was found to effectively reduce nitrite levels in fresh spinach during storage; levels in the late period were 30 to 40% lower than that of the control. However, the nitrate levels in fresh spinach during storage were not influenced by EOW treatment. The reduction of nitrite levels in EOW-treated fresh spinach during storage can be attributed to the inactivation of nitrate reductase directly and to the reduction of bacterial populations. Our results suggest that treatment with slightly acidic electrolyzed water may be a better choice to control nitrite levels in fresh vegetables during storage. This study provided a useful method to reduce nitrite levels in fresh spinach. PMID:25719879

  3. Simple quantitative analysis of Escherichia coli K-12 internalized in baby spinach using Fourier Transform Infrared spectroscopy.

    PubMed

    Wang, Jun; Kim, Kyung Ho; Kim, Sungkyun; Kim, Yong Soo; Li, Qing X; Jun, Soojin

    2010-11-15

    Bacterial contamination continues to be a serious concern for food safety. Although washing fresh produce helps in reducing pathogen levels, pathogen internalization often limits the effectiveness of washing. When pathogens internalize in leafy vegetables, the method of identification and quantitative measurement would be called into question. This study was aimed to use Fourier Transform Infrared (FTIR) spectroscopy integrated with an attenuated total reflectance kit for quantification of Escherichia coli K-12 internalized in baby spinach. The bacteria were inoculated into vascular and intracellar tissues of spinach leaves by syringe injection and the distribution of internalized E. coli K-12 cells was confirmed under scanning electron microscopy (SEM). FTIR measurement following the preparation of bacterial suspension from spinach leaves with high speed pulverizing enabled to detect the absorbance peaks in the amide II region between 1590 and 1490 cm?¹ as a fingerprint for the microbes. It was found that the estimated concentrations of E. coli K-12 agreed well with the concentrations determined by plate counting with R² values of 0.98 and 0.97 in peptone water and spinach extracts, respectively. The results demonstrated that FTIR can identify and quantify E. coli K-12 in baby spinach extracts at a limit of detection of approximately 100 CFU/mL in 5 min. The developed method is expected to be suitable for the analysis of pathogenic E. coli strains and other bacterial species in fresh vegetables. PMID:20937537

  4. UPDATE ON THE PERFORMANCE OF TRANSGENIC COTTON OVER-EXPRESSING SUCROSE PHOSPHATE SYNTHASE

    E-print Network

    Strauss, Richard E.

    for beneficial change. Analogously to other transgenic plants, we predicted that increased SPS activity might that, in a growth chamber test under 30/15°C day/night temperatures, these transgenic plants showed in 1999. In both cases, transgenic plants grew similarly to controls. Twelve representatives of nine

  5. Effects of Sucrose, Phosphate, and Calcium Carbonate on the Production of Pikromycin from Streptomyces venezuelae.

    PubMed

    Yi, Jeong Sang; Kim, Min-Suk; Kim, Sung-Jin; Kim, Byung-Gee

    2015-04-28

    Polyketide secondary metabolites share common precursor pools, acyl-CoA. Thus, the effects of engineering strategies for heterologous and native secondary metabolite production are often determined by the measurement of pikromycin in Streptomyces venezuelae. It is hard to compare the effectiveness of engineering targets among published data owing to the different pikromycin production media used from one study to the other. To determine the most important nutritional factor and establish optimal culture conditions, medium optimization of pikromycin from Streptomyces venezuelae ATCC 15439 was studied with a statistical method, Plackett-Burman design. Nine variables (glucose, sucrose, peptone, (NH4)2SO4, K2HPO4, KH2PO4, NaCl, MgSO4·7H2O, and CaCO3) were analyzed for their effects on a response, pikromycin. Glucose, K2HPO4, and CaCO3 were determined to be the most significant factors. The path of the steepest ascent and response surface methodology about the three selected components were performed to study interactions among the three factors, and the fine-tune concentrations for maximized product yields. The significant variables and optimal concentrations were 139 g/1 sucrose, 5.29 g/l K2HPO4, and 0.081 g/l CaCO3, with the maximal pikromycin yield of 35.5 mg/l. Increases of the antibiotics production by 1.45-fold, 1.3-fold, and 1.98-fold, compared with unoptimized medium and two other pikromycin production media SCM and SGGP, respectively, were achieved. PMID:25341465

  6. Fate of Escherichia coli O157:H7 in the presence of indigenous microorganisms on commercially packaged baby spinach as impacted by storage temperature and time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the effect of storage temperature and time on the survival and growth of Escherichia coli O157:H7, the growth of indigenous microorganisms, and the changes in product quality of packaged baby spinach. Commercial packages of spinach within 2 days of processing were cut at one en...

  7. Detection of the downy mildew pathogens of spinach (Peronospora effusa) and beet (P. schachtii) using spore traps and quantitative PCR assays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy mildew of spinach, caused by Peronospora effusa, is a disease constraint on spinach production worldwide. The aim of this study was to develop a real-time quantitative PCR assay for detection of airborne inoculum of P. effusa in California. This type of assay may, in combination with disease-...

  8. Coupling spore traps and quantitative PCR assays for detection of the downy mildew pathogens of spinach (Peronospora effusa) and beet (Peronospora schachtii)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Downy mildew of spinach (Spinacia oleracea L.), caused by Peronospora effusa, is a disease constraint on production worldwide, including in California where the majority of United States spinach is grown. The aim of this study was to develop a real-time quantitative PCR (qPCR) assay for detection o...

  9. Leaf Pack Network

    NSDL National Science Digital Library

    The Leaf Pack Network (LPN) is a network of teachers and students investigating their local stream ecosystems by participating in the leaf pack experiment, which involves creating an artificial leaf pack (dry leaves in a mesh bag), immersing it in a stream for 3-4 weeks, and examining it for signs of aquatic insects as indicators of stream health. Participating classrooms share their data through the internet. This activity highlights the connection between streamside forests and the ecology of rivers and streams.

  10. Element contents and food safety of water spinach (Ipomoea aquatica Forssk.) cultivated with wastewater in Hanoi, Vietnam.

    PubMed

    Marcussen, Helle; Joergensen, Karin; Holm, Peter E; Brocca, Daniela; Simmons, Robert W; Dalsgaard, Anders

    2008-04-01

    Extensive aquatic or semi-aquatic production of water spinach (Ipomoea aquatica Forssk.) for human consumption takes place in Southeast Asia. The aim of this study was to assess the concentrations of 38 elements in soil and water spinach cultivated under different degrees of wastewater exposure in Hanoi, Vietnam. The results showed no effect of wastewater use on the overall element concentrations in soil and water spinach. Mean soil concentrations for selected potentially toxic elements at the studied field sites had the following ranges 9.11-18.7 As, 0.333-0.667 Cd, 10.8-14.5 Co, 68-122 Cr, 34.0-62.1 Cu, 29.9-52.8 Ni, 32.5-67.4 Pb, 0.578-0.765 Tl and 99-189 Zn mg kg(-1) dry weight (d.w.). In all samples Cd, Pb and Zn soil concentrations were below the Vietnamese Guideline Values (TCVN 7209-2002) for agricultural soils whereas As and Cu exceeded the guideline values. Maximum site element concentrations in water spinach were 0.139 As, 0.032 Cd, 0.135 Cr, 2.01 Cu, 39.1 Fe, 57.3 Mn, 0.16 Ni, 0.189 Pb and 6.01 Zn mg kg(-1) fresh weight (f.w.). The site and soil content of organic carbon were found to have high influence on the water spinach element concentrations whereas soil pH and the total soil element concentrations were of less importance. The estimated average daily intake of As, Cd, Cu, Fe, Pb and Zn for adult Vietnamese consumers amounts to <11% of the maximum tolerable intake proposed by FAO/WHO for each element. It is assessed that the occurrence of the investigated elements in water spinach will pose low health risk for the consumers. PMID:17593534

  11. Radiosensitization of Salmonella spp. and Listeria spp. in ready-to-eat baby spinach leaves.

    PubMed

    Gomes, Carmen; Moreira, Rosana G; Castell-Perez, Elena

    2011-01-01

    The FDA recently approved irradiation treatment of leafy greens such as spinach up to 1 kGy; however, it is important to reduce the dose required to decontaminate the produce while maintaining its quality. Thus, the objectives of this study were: (1) to assess the radiation sensitivities of Salmonella spp. and Listeria spp. inoculated in ready-to-eat baby spinach leaves under modified atmosphere packaging (MAP) and irradiated using a 1.35-MeV Van de Graff accelerator (the leaves were irradiated both at room temperature and at -5 °C); and (2) to understand and optimize the synergistic effect of MAP and irradiation by studying the radiolysis of ozone formation under different temperatures, the effect of dose rate on its formation, and its decomposition. Results showed that increased concentrations of oxygen in the packaging significantly increased the radiation sensitivity of the test organisms, ranging from 7% up to 25% reduction in D(10)-values. In particular, radiosensitization could be effected (P < 0.05) by production of ozone, which increases with increasing dose-rate and oxygen concentration, and reducing temperatures. Radiosensitization was demonstrated for both microorganisms with irradiation of either fresh or frozen (-5 °C) baby spinach. These results suggest that low-dose (below 1 kGy) e-beam radiation under modified atmosphere packaging (100% O(2) and N(2):O(2)[1:1]) may be a viable tool for reducing microbial populations or eliminating Salmonella spp. and Listeria spp. from baby spinach. A suggested treatment to achieve a 5-log reduction of the test organisms would be irradiation at room temperature under 100% O(2) atmosphere at a dose level of 0.7 kGy. Practical Application: Decontamination of minimally processed fruits and vegetables from food-borne pathogens presents technical and economical challenges to the produce industry. Internalized microorganisms cannot be eliminated by the current procedure (water-washed or treated with 200-ppm chlorine). The only technology available commercially is ionizing radiation; however, the actual radiation dose required to inactivate pathogens is too high to be tolerated by the product without unwanted changes. This study shows a new approach in using MAP with 100% O(2), which is converted to ozone to radiosensitize pathogens while improving the shelf life of minimally processed fruits and vegetables. The process results in a high level of microorganism inactivation using lower doses than the conventional irradiation treatments. PMID:21535665

  12. Studies of two cucumber mosaic virus isolates from spinach in the winter garden area of Texas 

    E-print Network

    Wilson, Alphus Dan

    1983-01-01

    were commonly found in epidermal cells of CMU-infected tobacco. The inclusions were either angular and crystalline or amorphous and diffuse with or without clear centers. The isolates were found to be identical based on host ranges and serological...eld and UV analysis data from purif1cat1on trials of spinach v1rus isolates 'C' and 'M' propagated in tobacco. 17 CMV genomic RNA electrophoresis trials 18 CMV protein subun1t electrophoresis trials Page 81 83 107 110 LIST OF FIGURES FIGURE...

  13. [Molecular mechanism of leaf development].

    PubMed

    Yan, Song; Yan, Chang-Jie; Gu, Ming-Hong

    2008-09-01

    Leaf plays important roles during plant development for their function of photosynthesis and transpiration. Leaf development includes initiation of leaf primordium and establishment of leaf polarity. Various studies indicate that leaf development is controlled through the interaction of transcription factors, small RNAs and auxin. This review focuses on re-cent advances in studying on leaf development and morphogenesis, and provides information on the regulation network in the process. PMID:18779169

  14. ASCOCHYTA LEAF SPOT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ascochyta leaf spot is a plant disease of wheat. It is often overlooked in association with other leaf spot diseases on wheat and is generally of minor economic importance in Europe, Japan, New Zealand, and North America. However, its distribution and frequency may be greater than realized, becaus...

  15. Leaf cutter ants

    NSDL National Science Digital Library

    N/A N/A (None; )

    2007-12-15

    There is much diversity between ants. Leaf cutter ants use their mandibles to cut leaf fragments and take them back to their home. They don't eat the leaves, but instead use them to grow fungus on. They then eat the fungus.

  16. Single Molecule Manipulation and Spectroscopy of Chlorophyll-a from Spinach

    NASA Astrophysics Data System (ADS)

    Benson, Jessica-Jones

    2005-03-01

    Chlorophyll-a, a molecule produced from `Spinach', adsorbed on a Au(111) surface has been investigated by using an ultra-high-vacuum low-temperature scanning-tunneling-microscope (UHV-LT-STM) at liquid helium temperatures. Studies are carried out both on isolated single molecules and on self-assembled molecular layers. The tunneling I-V and dI-dV spectroscopy of chlorophyll-a elucidate electronic properties of single molecule, such as the HOMO-LOMO gap and molecular orbital states. Mechanical stability of the chlorophyll-a is examined by using STM lateral manipulation (1,2). Here, the STM tip is placed just a few angstrom separation from the molecule to increase the tip-molecule interaction. Then the tip is laterally scanned across the surface resulting in pulling of the molecule. The detailed molecule movement is directly monitored through the corresponding STM-tip height signals. Our results reveal that the spinach molecule is a promising candidate for environmental friendly nano-device applications. (1). S.-W. Hla, K.-H. Rieder, Ann. Rev. Phys. Chem. 54 (2003) 307-330. (2). S.-W. Hla, et al. Phys. Rev. Lett. 93 (2004), 208302. This work is financially supported by the US-DOE grant DE-FG02-02ER46012.

  17. Global Leaf Trait Relationships: Mass, Area, and the Leaf

    E-print Network

    Minnesota, University of

    Global Leaf Trait Relationships: Mass, Area, and the Leaf Economics Spectrum Jeanne L. D. Osnas,1,2 * Jeremy W. Lichstein,2 Peter B. Reich,3,4 Stephen W. Pacala1 The leaf economics spectrum (LES) describes multivariate correlations that constrain leaf traits of plant species primarily to a single axis of variation

  18. Short communication Leaf optical properties and photosynthetic leaf absorptances

    E-print Network

    Durako, Michael J.

    Short communication Leaf optical properties and photosynthetic leaf absorptances in several-species variability in the leaf optical properties of eight large-bodied seagrasses, Posidonia australis, Posidonia of Australia. Leaf spectral transmittance [TL(l)], reflectance [RL(l)], and non-photosynthetic absorptance [AL

  19. THE EFFECTS OF ELECTRON BEAM IRRADIATION AND SANITIZERS IN THE REDUCTION OF PATHOGENS AND ATTACHMENT PREVENTION ON SPINACH 

    E-print Network

    Neal, Jack A.

    2010-07-14

    and internalization of the pathogens on spinach. The greatest reduction by a chemical sanitizer was 55?C L-lactic acid with a 2.7 log CFU/g reduction for E. coli O157:H7 and 2.3 log CFU/g reduction for Salmonella. Each dose of e-beam irradiation significantly reduced...

  20. Characterization of the cultivable microbial community in a spinach-processing plant using MALDI-TOF MS.

    PubMed

    Hausdorf, Lena; Mundt, Kerstin; Winzer, Michaela; Cordes, Christiana; Fröhling, Antje; Schlüter, Oliver; Klocke, Michael

    2013-06-01

    A better and regular control of the production chain of fresh fruits and vegetables is necessary, because a contamination of the product by human- and phyto-pathogenic microorganisms may result in high losses during storage and poses a threat to human health. Therefore, detailed knowledge about the occurrence and the diversity of microorganisms within single processing steps is required to allow target-oriented produce safety control. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was successfully used to identify bacterial colonies. Bacteria can be identified with high accuracy by comparing them with generated spectra of a reference database. In this study, spinach and wash water samples were taken of the complete process line of a spinach-washing plant. Bacteria in the samples were grown on plate-count, Arcobacter selective, marine and blood agar. In total, 451 colonies were evaluated by MALDI-TOF MS, 16S rRNA gene sequence and phylogenetic analysis. 50% of the detected species belonged to the class of Gammaproteobacteria. Firmicutes were present with 22%. Mostly, the detected species showed 16S rRNA gene sequence dissimilarities larger than 1% to known reference species and, hence, could not be assigned to a distinct species. However, many isolated species belonged to genera which contain pathogenic or opportunistic pathogenic bacteria. In addition, the bacterial diversity on the spinach surface increased after the first washing step indicating a process-borne contamination of the spinach. PMID:23541209

  1. Escherichia coli O157:H7 in feral swine near spinach fields and cattle, central California coast.

    PubMed

    Jay, Michele T; Cooley, Michael; Carychao, Diana; Wiscomb, Gerald W; Sweitzer, Richard A; Crawford-Miksza, Leta; Farrar, Jeff A; Lau, David K; O'Connell, Janice; Millington, Anne; Asmundson, Roderick V; Atwill, Edward R; Mandrell, Robert E

    2007-12-01

    We investigated involvement of feral swine in contamination of agricultural fields and surface waterways with Escherichia coli O157:H7 after a nationwide outbreak traced to bagged spinach from California. Isolates from feral swine, cattle, surface water, sediment, and soil at 1 ranch were matched to the outbreak strain. PMID:18258044

  2. Escherichia coli O157:H7 in Feral Swine Near Spinach Fields and Cattle, Central California Coast

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated involvement of feral swine in contamination of agriculture fields and surface waterways with Escherichia coli O157:H7 after a nationwide outbreak traced to bagged spinach from California. Isolates from feral swine, cattle, surface water, sediment, and soil at 1 ranch were matched to ...

  3. Quality of fresh-cut Iceberg lettuce and spinach irradiated at doses up to 4 kGy

    NASA Astrophysics Data System (ADS)

    Fan, Xuetong; Guan, Wenqiang; Sokorai, Kimberly J. B.

    2012-08-01

    Fresh-cut Iceberg lettuce packaged in modified atmosphere packages and spinach in perforated film bags were irradiated with gamma rays at doses of 0, 1, 2, 3, and 4 kGy. After irradiation, the samples were stored for 14 days at 4 °C. O2 levels in the packages of fresh-cut Iceberg lettuce decreased and CO2 levels increased with increasing radiation dose, suggesting that irradiation increased respiration rates of lettuce. Tissue browning of irradiated cut lettuce was less severe than that of non-irradiated, probably due to the lower O2 levels in the packages. However, samples irradiated at 3 and 4 kGy had lower maximum force and more severe sogginess than the non-irradiated control. In addition, ascorbic acid content of irradiated lettuce was 22-40% lower than the non-irradiated samples after 14 days of storage. The visual appearance of spinach was not affected by irradiation even at a dose of 4 kGy. Consumer acceptance suggested that more people would dislike and would not buy spinach that was treated at 3 and 4 kGy as compared to the non-irradiated sample. Overall, irradiation at doses of 1 and 2 kGy may be employed to enhance microbial safety of fresh-cut Iceberg lettuce and spinach while maintaining quality.

  4. Effect of Nd3+ ion on carboxylation activity of ribulose-1,5-bisphosphate carboxylase/oxygenase of spinach.

    PubMed

    Liu, Chao; Hong, Fa-shui; Wu, Kang; Ma, Hong-bing; Zhang, Xue-guang; Hong, Cheng-jiao; Wu, Cheng; Gao, Feng-qing; Yang, Fan; Zheng, Lei; Wang, Xue-feng; Liu, Tao; Xie, Ya-ning; Xu, Jian-hua; Li, Zhong-rui

    2006-03-31

    Neodymium (Nd), as a member of rare earth elements, proved to enhance the photosynthesis rate and organic substance accumulation of spinach through the increase in carboxylation activity of Rubisco. Although the oxygenase activity of spinach Rubisco was slightly changed with the Nd(3+) treatment, the specific factor of Rubisco was greatly increased. It was partially due to the promotion of Rubisco activase (R-A) activity but mainly to the formation of Rubisco-Rubisco activase super-complex, a heavier molecular mass protein (about 1200kD) comprising both Rubisco and Rubisco activase. This super-complex was found during the extraction procedure of Rubisco by the gel electrophoresis and Western-blot studies. The formation of Rubisco-R-A super-complex suggested that the secondary structure of the protein purified from the Nd(3+)-treated spinach was different from that of the control. Extended X-ray absorption fine structure study of the 'Rubisco' purified from the Nd(3+)-treated spinach revealed that Nd was bound with four oxygen atoms and two sulfur atoms of amino acid residues at the Nd-O and Nd-S bond lengths of 2.46 and 2.89A, respectively. PMID:16469293

  5. Growth Stage Modulates Salinity Tolerance of New Zealand Spinach ( Tetragonia tetragonioides, Pall.) and Red Orach ( Atriplex hortensis L.)

    Microsoft Academic Search

    Clyde Wilson; Scott M. Lesch; Catherine M. Grieve

    2000-01-01

    The response of two speciality vegetable crops, New Zealand spinach (Tetragonia tetragonioides Pall.) and red orach (Atriplex hortensis L.), to salt application at three growth stages was investigated. Plants were grown with a base nutrient solution in outdoor sand cultures and salinized at 13 (early), 26 (mid), and 42 (late) d after planting (DAP). For the treatment salt concentrations, we

  6. Use of Spinach, Radish, and Perennial Ryegrass to Assess the Availability of Metals in Waste Foundry Sands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant uptake is a major pathway by which potentially toxic metals can enter the food chain. In this laboratory study we grew spinach, radish, and perennial ryegrass in sand blends containing 50% waste foundry sand (WFS) to assess the availability of Al, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn,...

  7. The relationship between the structure of plastoquinone derivatives and their biological activity in Photosystem II of spinach chloroplasts

    Microsoft Academic Search

    Ben-Li Liu; Arnold J. Hoff; Lian-Quan Gu; Liang-Bi Li; Pei-Zhen Zhou

    1991-01-01

    The relationship between the structure of reconstituted plastoquinone derivatives and their ability to recover the Hill reaction was investigated by extraction and reconstitution of lyophilized chloroplasts from spinach, followed by monitoring DCIP photoreduction at 600 nm. The results show that: It is not essential that the plastoquinone side chain be an isoprenoid or a phytol; the activity increases with increasing

  8. SlowRelease Zeolite-Bound Zinc and Copper Fertilizers Affect Cadmium Concentration in Wheat and Spinach

    Microsoft Academic Search

    Markus Puschenreiter; Othmar Horak

    2003-01-01

    Cadmium (Cd) accumulation in crops is considered one of the major problems which agriculture faces in industrial and urban areas. This study was conducted to determine the influence of fertilization with slow-release zeolite-bound zinc and copper on the cadmium uptake of wheat (Triticum aestivum L., cv. Nandu) and spinach (Spinacia oleracea L., cv. Matador), two crops with higher tendency to

  9. Elm Leaf Beetle 

    E-print Network

    Patrick, Carl D.

    2002-05-22

    stream_source_info pdf_1591.pdf.txt stream_content_type text/plain stream_size 5918 Content-Encoding UTF-8 stream_name pdf_1591.pdf.txt Content-Type text/plain; charset=UTF-8 Elm Leaf Beetles L-1812 5-02 Carl D. Patrick... overwintering sites. *Extension Entomologist, The Texas A&M University System. Elm leaf beetle adult. Damage Elm leaf beetles feed exclusively on foliage. Adult feeding causes small, circular holes in leaves. Larval feeding removes most of the green material...

  10. Combination treatment of chlorine dioxide gas and aerosolized sanitizer for inactivating foodborne pathogens on spinach leaves and tomatoes.

    PubMed

    Park, Sang-Hyun; Kang, Dong-Hyun

    2015-08-17

    The objective of this study was to evaluate the antimicrobial effect of chlorine dioxide (ClO2) gas and aerosolized sanitizer, when applied alone or in combination, on the survival of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes inoculated onto spinach leaves and tomato surfaces. Spinach leaves and tomatoes were inoculated with a cocktail of three strains each of the three foodborne pathogens. ClO2 gas (5 or 10ppmv) and aerosolized peracetic acid (PAA) (80ppm) were applied alone or in combination for 20min. Exposure to 10ppmv of ClO2 gas for 20min resulted in 3.4, 3.3, and 3.4 log reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes on spinach leaves, respectively. Treatment with 80ppm of aerosolized PAA for 20min caused 2.3, 1.9, and 0.8 log reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively. Combined treatment of ClO2 gas (10ppmv) and aerosolized PAA (80ppm) for 20min caused 5.4, 5.1, and 4.1 log reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively. E. coli O157:H7, S. Typhimurium, and L. monocytogenes on tomatoes experienced similar reduction patterns to those on spinach leaves. As treatment time increased, most combinations of ClO2 gas and aerosolized PAA showed additive effects in the inactivation of the three pathogens. Combined treatment of ClO2 gas and aerosolized PAA produced injured cells of three pathogens on spinach leaves while generally did not produce injured cells of these pathogens on tomatoes. Combined treatment of ClO2 gas (10ppmv) and aerosolized PAA (80ppm) did not significantly (p>0.05) affect the color and texture of samples during 7days of storage. PMID:26001524

  11. E-Beam irradiation of bagged, ready-to-eat spinach leaves (Spinacea oleracea): an engineering approach.

    PubMed

    Gomes, C; Moreira, R G; Castell-Perez, M E; Kim, J; Da Silva, P; Castillo, A

    2008-03-01

    We experimentally assessed the efficacy of electron beam irradiation to ensure the safety and quality of ready-to-eat spinach leaves using a 2-MeV Van de Graff accelerator. Spinach leaves (approximately 8 g) inside petri dishes were irradiated up to 1 kGy and stored at 4 degrees C for 15 d. Nonirradiated samples served as controls. Color, texture, vitamin C, total carotenoids, and chlorophyll content were measured using standard methods. Sensory analysis was performed by 15 untrained panelists using a 9-point hedonic scale. Color of control and irradiated samples showed slight variation throughout storage. Firmness of all samples changed significantly (P < 0.05) by half the storage time; however, exposure to radiation did not cause significant differences by the end of shelf life. Irradiation did not affect the chlorophyll and total carotenoid content, though it produced samples with significantly lower (P < 0.05) vitamin C content. For all treatments, chlorophyll content decreased by day 15 while total carotenoids remained constant. Although, by the end of refrigerated storage, all the irradiated samples received slightly lower odor scores, sensory analysis revealed that irradiation had little or no effect on the overall quality of spinach leaves. We also simulated the dose distribution within a bag of spinach leaves irradiated using a 10-MeV linear accelerator (0.3 to 1 kGy) to quantify the problem of nonuniform dose absorbed at different parts of the bag and predict death of a pathogen such as Escherichia coli O157:H7. The simulation results confirmed that it is feasible to irradiate baby spinach leaves (up to 1 kGy) to eliminate E. coli 0157:H7 while maintaining the overall quality of the produce. PMID:18298731

  12. Electronic Leaf Project

    NSDL National Science Digital Library

    Carolyn Houston

    2000-05-01

    This article demonstrates the benefits of a direct application of technology into a science classroom by transferring a traditional activity, such as leaf identification, into an electronic format. The new dynamic medium possesses attributes that can enha

  13. 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

  14. Leaf to Landscape

    Microsoft Academic Search

    Alessandro Cescatti; Ülo Niinemets

    \\u000a Temporal dynamics and structural complexity of plant canopies strongly affect light harvesting, generating variable spatio-temporal\\u000a distributions of the irradiance on leaf area (Baldocchi and Collineau 1994). Leaf light interception scales linearly with\\u000a incident irradiance, but plant photosynthesis and photomorphogenesis typically exhibit a saturating response to light. Because\\u000a of the inherent nonlinearity in light responses, estimates of the photosynthetic rate at

  15. Survival of Salmonella hadar after washing disinfection of minimally processed spinach.

    PubMed

    Pirovani, M E; Güemes, D R; Di Pentima, J H; Tessi, M A

    2000-08-01

    Washing disinfection with chlorine is widely used to reduce the initial microbiological load during the preparation of minimally processed vegetables. The effects of initial concentration of chlorine, time and the liquid volume:produce weight ratio on the reduction of Salmonella counts on inoculated spinach were evaluated using response surface methodology. Initial chlorine concentration, time and the interaction between them had a significant effect on reduction of Salmonella populations. However, the liquid volume:produce weight ratio did not have significant effects. The highest Salmonella reduction was around 1.2-1.4 log at 125 ppm during 8 min regardless of the water:produce ratio. According to the results, chlorination reduced Salmonella hadar population, but the complete elimination from the produce was not achieved. PMID:10972717

  16. Visible light absorption and photo-sensitizing properties of spinach leaves and beetroot extracted natural dyes

    NASA Astrophysics Data System (ADS)

    Sengupta, D.; Mondal, B.; Mukherjee, K.

    2015-09-01

    Herein, chlorophyll and betalain dyes are extracted from fresh spinach leaves and beetroots. Fourier transform infrared spectra are used to identify the characteristic peaks of the extracted dyes. UV-vis light absorption characteristics of the dyes and their mixed counterpart are investigated by varying their pH and temperature. These dyes are used as photo sensitizer for fabrication of zinc oxide photo-anode based dye sensitized solar cells (DSSCs). The photo-voltaic characteristics of the developed DSSCs are measured under simulated solar light (power of incident light 100 mW cm-2 from Air Mass 1.5G). The solar to electric conversion efficiencies for the chlorophyll, betalain and mixed dye based solar cells are estimated as 0.148%, 0.197% and 0.294% respectively. The highest conversion efficiency for mixed dye based solar cell is attributed due to the absorption of wider range of solar spectrum.

  17. Physiological Rates of Starch Breakdown in Isolated Intact Spinach Chloroplasts 1

    PubMed Central

    Stitt, Mark; Heldt, Hans W.

    1981-01-01

    Starch breakdown with rates above 10 ?atom carbon per mg chlorophyll per hour has been monitored in spinach chloroplasts and compares favorably with the rates in whole leaves. Intact starch-loaded chloroplasts were prepared from protoplasts to avoid rupture during mechanical homogenization and rapid centrifugation. Particular attention was paid to the identification of all the products of starch degradation and to measuring the actual rates of their accumulation. The products of starch breakdown included triose phosphate, 3-phosphoglycerate, CO2, glucose, and some maltose. Comparison of the rates of metabolism of added glucose and of the conversion of starch to phosphorylated intermediates showed that starch phosphorolysis was the major pathway leading to phosphorylated endproducts. From the results, the relative contribution of phosphorolysis and hydrolysis to starch breakdown and the contribution of glycolysis and the oxidative pentose phosphate cycle can be estimated. Phosphate has a large influence on the metabolism of the chloroplast in the dark. PMID:16661994

  18. Visible light absorption and photo-sensitizing properties of spinach leaves and beetroot extracted natural dyes.

    PubMed

    Sengupta, D; Mondal, B; Mukherjee, K

    2015-09-01

    Herein, chlorophyll and betalain dyes are extracted from fresh spinach leaves and beetroots. Fourier transform infrared spectra are used to identify the characteristic peaks of the extracted dyes. UV-vis light absorption characteristics of the dyes and their mixed counterpart are investigated by varying their pH and temperature. These dyes are used as photo sensitizer for fabrication of zinc oxide photo-anode based dye sensitized solar cells (DSSCs). The photo-voltaic characteristics of the developed DSSCs are measured under simulated solar light (power of incident light 100mWcm(-2) from Air Mass 1.5G). The solar to electric conversion efficiencies for the chlorophyll, betalain and mixed dye based solar cells are estimated as 0.148%, 0.197% and 0.294% respectively. The highest conversion efficiency for mixed dye based solar cell is attributed due to the absorption of wider range of solar spectrum. PMID:25875029

  19. Investigation of Detergent Effects on the Solution Structure of Spinach Light Harvesting Complex II

    SciTech Connect

    Cardoso, Mateus B [ORNL; Smolensky, Dmitriy [ORNL; Heller, William T [ORNL; O'Neill, Hugh Michael [ORNL

    2010-01-01

    The properties of spinach light harvesting complex II (LHC II), stabilized in the detergents Triton X-100 (TX100) and n-Octyl-{beta}-D-Glucoside (BOG), were investigated by small-angle neutron scattering (SANS). The LHC II-BOG scattering curve overlaid well with the theoretical scattering curve generated from the crystal structure of LHC II indicating that the protein preparation was in its native functional state. On the other hand, the simulated LHC II curve deviated significantly from the LHC II-TX100 experimental data. Analysis by circular dichroism spectroscopy supported the SANS analysis and showed that LHC II-TX100 is inactivated. This investigation has implications for extracting and stabilizing photosynthetic membrane proteins for the development of biohybrid photoconversion devices.

  20. Organ-specific distribution of chlorophyll-related compounds from dietary spinach in rabbits.

    PubMed

    Hsu, Ching-Yun; Yeh, Tsan-Huei; Huang, Meng-Yuan; Hu, Shene-Pin; Chao, Pi-Yu; Yang, Chi-Ming

    2014-10-01

    The distribution of chlorophyll-related compounds (CRCs) derived from dietary spinach was investigated in different organs the rabbits. The rabbits in the experimental group consumed 100 g of freeze-dried spinach powder after a 24 h fasting period and sacrificed 2, 4, 8, 12 and 24 h later and in the control group sacrificed after the 24 h fasting period. The main CRCs in the liver were found to be chlorophyll (Chl a) and b, chlorophyllide (Chlide) a and b, pheophytin (Phe) a and b and pheophorbide (Pho) a and b, which reached their peak values at 8 h post-feeding. The gallbladder contained mainly Chlide a and a', Pho a and a', Pho b and b', which peaked their values at 2 h post-feeding. Pho a and b were consistently observed in the blood and peaked at 12 h post-feeding. The earlier appearance of Chlide a', Pho a' and Pho b' in the gallbladder compared to the liver indicated that these CRCs were compartmentalized differently and might undergo the same type of vectorialized transport as characterized for the bile salts. Pho levels peaked later in the blood compared to the liver, suggesting that Pho might be released into the peripheral blood circulation from the liver. In conclusion, Chlide and Pho were the principal Chl metabolites in the rabbits. Our data may expand our understanding of the metabolism and biodistribution of CRCs in the human body. A number of biological functions, including anti-oxidation, anti-tumor and anti-aging have recently been attributed to CRCs, it will be interesting to explore, if the binding of Chlide and Pho to other nutrients or trace metal ions in the body mediate their biological functions. PMID:25630109

  1. Performance of two Trichogramma brassicae strains under greenhouse and field conditions for biocontrol of the silver Y moth in spinach cultures

    Microsoft Academic Search

    Thomas Klug; Rainer Meyhöfer

    2009-01-01

    The suitability of Trichogramma\\u000a brassicae Bezd. (Hymenoptera: Trichogrammatidae) to control the silver Y moth, Autographa gamma (L.) (Lepidoptera: Noctuidae) in spinach was investigated under greenhouse and field conditions. Two strains of T. brassicae were selected to study host searching efficiency and dispersal ability of the wasps on spinach. The experiments were conducted\\u000a with defined release densities. The results show that

  2. 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.

  3. 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

  4. The acute effect of flavonoid-rich apples and nitrate-rich spinach on cognitive performance and mood in healthy men and women.

    PubMed

    Bondonno, Catherine P; Downey, Luke A; Croft, Kevin D; Scholey, Andrew; Stough, Con; Yang, Xingbin; Considine, Michael J; Ward, Natalie C; Puddey, Ian B; Swinny, Ewald; Mubarak, Aidilla; Hodgson, Jonathan M

    2014-05-01

    Flavonoids and nitrate in a fruit and vegetable diet may be protective against cardiovascular disease and cognitive decline through effects on nitric oxide (NO) status. The circulating NO pool is increased via distinct pathways by dietary flavonoids and nitrate. Our aim was to investigate the acute effects of apples, rich in flavonoids, and spinach, rich in nitrate, independently and in combination on NO status, cognitive function and mood in a randomised, controlled, cross-over trial with healthy men and women (n = 30). The acute effects of four energy-matched treatments (control, apple, spinach and apple + spinach) were compared. Endpoints included plasma nitric oxide status (determined by measuring S-nitrosothiols + other nitroso species (RXNO)), plasma nitrate and nitrite, salivary nitrate and nitrite, urinary nitrate and nitrite as well as cognitive function (determined using the Cognitive Drug Research (CDR) computerized cognitive assessment battery) and mood. Relative to control, all treatments resulted in higher plasma RXNO. A significant increase in plasma nitrate and nitrite, salivary nitrate and nitrite as well as urinary nitrate and nitrite was observed with spinach and apple + spinach compared to control. No significant effect was observed on cognitive function or mood. In conclusion, flavonoid-rich apples and nitrate-rich spinach augmented NO status acutely with no concomitant improvements or deterioration in cognitive function and mood. PMID:24676365

  5. LEAF GUI: User Manual (Leaf Extraction and Analysis Framework Graphical User Interface)

    E-print Network

    Weitz, Joshua S.

    LEAF GUI: User Manual (Leaf Extraction and Analysis Framework Graphical User Interface) #12;LEAF GUI User Manual Price et al. Index How to cite the LEAF GUI.......................................................................................................................Page 4 Overview of the LEAF GUI layout

  6. Effects of mercury on visible/near-infrared reflectance spectra of mustard spinach plants (Brassica rapa P.).

    PubMed

    Dunagan, Sarah C; Gilmore, Martha S; Varekamp, Johan C

    2007-07-01

    Mustard spinach plants were grown in mercury-spiked and contaminated soils collected in the field under controlled laboratory conditions over a full growth cycle to test if vegetation grown in these soils has discernible characteristics in visible/near-infrared (VNIR) spectra. Foliar Hg concentrations (0.174-3.993ppm) of the Mustard spinach plants were positively correlated with Hg concentration of soils and varied throughout the growing season. Equations relating foliar Hg concentration to spectral reflectance, its first derivative, and selected vegetation indices were generated using stepwise multiple linear regression. Significant correlations are found for limited wavelengths for specific treatments and dates. Ratio Vegetation Index (RVI) and Red Edge Position (REP) values of plants in Hg-spiked and field-contaminated soils are significantly lower relative to control plants during the early and middle portions of the growth cycle which may be related to lower chlorophyll abundance or functioning in Hg-contaminated plants. PMID:17188786

  7. pH dependent chlorophyll fluorescence quenching in spinach thylakoids from light treated or dark adapted leaves

    Microsoft Academic Search

    Deborah Rees; Graham Noctor; Alexander V. Ruban; Jane Crofts; Andrew Young; Peter Horton

    1992-01-01

    The pH dependence of maximum chlorophyll fluorescence yield (Fm) was examined in spinach thylakoids in the presence of nigericin to dissipate the transthylakoid pH gradient. 3-(3',4'-dichlorophenyl)-1,1-dimethylurea (DCMU) was present to eliminate photochemical quenching. Thylakoids were prepared from dark adapted leaves (‘dark’ thylakoids) or preilluminated leaves (‘light’ thylakoids). In the latter there had been approximately 50% conversion of the xanthophyll violaxanthin

  8. Cadmium Phytoextraction Efficiency of Arum ( Colocasia antiquorum ), Radish ( Raphanus sativus L.) and Water Spinach ( Ipomoea aquatica ) Grown in Hydroponics

    Microsoft Academic Search

    Bal Ram Singh; S M Imamul Huq; Shigenao Kawai

    2008-01-01

    Selection of a phytoextraction plant with high Cd accumulation potential based on compatibility with mechanized cultivation\\u000a practice and local environmental conditions may provide more benefits than selection based mainly on high Cd tolerance plants.\\u000a In this hydroponics study, the potential of Cd accumulation by three plant species; arum (Colocasia antiquorum), radish (Raphanus sativus L.) and water spinach (Ipomoea aquatica) were

  9. Bioconversion of spinach beta-carotene to vitamin A in Chinese children with normal or marginal vitamin A status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To investigate the vitamin A conversion value of spinach beta-carotene (beta -C) in healthy school children with normal or marginal vitamin A status, we recruited 32 school children aged 7-9 y (7.8 ± 0.6 y) with serum retinol '30 mug/dL or <30mug/dL. Subjects were given 5 gram cooked and pureed deut...

  10. Leaf Hydraulics Lawren Sack1

    E-print Network

    Sack, Lawren

    Leaf Hydraulics Lawren Sack1 and N. Michele Holbrook2 1 Department of Botany, University of Hawai the leaf constitute a substantial (30%) part of the resistance to water flow through plants, and thus influence rates of transpiration and photosynthesis. Leaf hydraulic conductance (Kleaf) varies more than 65

  11. Differences in responses of summer and winter spinach to elevated UV-B at varying soil NPK levels.

    PubMed

    Singh, Suruchi; Agrawal, Madhoolika; Agrawal, S B

    2014-05-01

    Seasonal variations in response of spinach to elevated ultraviolet-B (UV-B) during summer and winter were assessed with respect to growth, biomass, yield, NPK uptake and NPK use efficiencies at varying NPK levels. The nutrient amendments were recommended NPK (RNPK) and 1.5 times recommended NPK (1.5 RNPK). Season significantly affected the measured parameters except the number of leaves. Under ambient UV-B, the growth performance of summer spinach was better in both the NPK levels, higher being at 1.5 RNPK leading to higher nutrient uptake. However, more reduction in biomass under elevated UV-B in 1.5 RNPK was recorded during summer, while during winter in RNPK. Reduction in biomass under elevated UV-B was accompanied by the modification in its partitioning with more biomass allocation to root during summer compared to winter at both the NPK levels. NPK uptake was higher in summer, while NPK use efficiencies were higher during winter. At higher than recommended NPK level, better NPK use efficiencies were displayed during both the seasons. Increased NPK supply during winter enabled spinach to capitalize light more efficiently and hence increased biomass accumulation. Strategies for surviving elevated UV-B in winter differ from those that provided protection from the same stress when it occurs in summer. PMID:24474564

  12. 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...

  13. The metabolic significance of octulose phosphates in the photosynthetic carbon reduction cycle in spinach

    PubMed Central

    MacLeod, John K.

    2006-01-01

    14C-Labelled octulose phosphates were formed during photosynthetic 14CO2 fixation and were measured in spinach leaves and chloroplasts. Because mono- and bisphosphates of d-glycero-d-ido-octulose are the active 8-carbon ketosugar intermediates of the L-type pentose pathway, it was proposed that they may also be reactants in a modified Calvin–Benson–Bassham pathway reaction scheme. This investigation therefore initially focussed only on the ido-epimer of the octulose phosphates even though 14C-labelled d-glycero-d-altro-octulose mono- and bisphosphates were also identified in chloroplasts and leaves. 14CO2 predominantly labelled positions 5 and 6 of d-glycero-d-ido-octulose 1,8-P2 consistent with labelling predictions of the modified scheme. The kinetics of 14CO2 incorporation into ido-octulose was similar to its incorporation into some traditional intermediates of the path of carbon, while subsequent exposure to 12CO2 rapidly displaced the 14C isotope label from octulose with the same kinetics of label loss as some of the confirmed Calvin pathway intermediates. This is consistent with octulose phosphates having the role of cyclic intermediates rather than synthesized storage products. (Storage products don’t rapidly exchange isotopically labelled carbons with unlabelled CO2.) A spinach chloroplast extract, designated stromal enzyme preparation (SEP), catalysed and was used to measure rates of CO2 assimilation with Calvin cycle intermediates and octulose and arabinose phosphates. Only pentose (but not arabinose) phosphates and sedoheptulose 7-phosphate supported CO2 fixation at rates in excess of 120 ?mol h?1 mg?1 Chl. Rates for octulose, sedoheptulose and fructose bisphosphates, octulose, hexose and triose monophosphates were all notably less than the above rate and arabinose 5-phosphate was inactive. Altro-octulose phosphates were more active than phosphate esters of the ido-epimer. The modified scheme proposed a specific phosphotransferase and SEP unequivocally catalysed reversible phosphate transfer between sedoheptulose bisphosphate and d-glycero-d-ido-octulose 8-phosphate. It was also initially hypothesized that arabinose 5-phosphate, an L-Type pentose pathway reactant, may have a role in a modified Calvin pathway. Arabinose 5-phosphate is present in spinach chloroplasts and leaves. Radiochromatography showed that 14C-arabinose 5-phosphate with SEP, but only in the presence of an excess of unlabelled ribose 5-phosphate, lightly labelled ribulose 5-phosphate and more heavily labelled hexose and sedoheptulose mono- and bisphosphates. However, failure to demonstrate any CO2 fixation by arabinose 5-phosphate as sole substrate suggested that the above labelling may have no metabolic significance. Despite this arabinose and ribose 5-phosphates are shown to exhibit active roles as enzyme co-factors in transaldolase and aldolase exchange reactions that catalyse the epimeric interconversions of the phosphate esters of ido- and altro-octulose. Arabinose 5-phosphate is presented as playing this role in a New Reaction Scheme for the path of carbon, where it is concluded that slow reacting ido-octulose 1,8 bisphosphate has no role. The more reactive altro-octulose phosphates, which are independent of the need for phosphotransferase processing, are presented as intermediates in the new scheme. Moreover, using the estimates of phosphotransferase activity with altro-octulose monophosphate as substrate allowed calculation of the contributions of the new scheme, that ranged from 11% based on the intact chloroplast carboxylation rate to 80% using the carboxylation rate required for the support of octulose phosphate synthesis and its role in the phosphotransferase reaction. PMID:17160443

  14. X-Ray Absorption Spectroscopy and EPR Studies of Oriented Spinach Thylakoid Preparations

    NASA Astrophysics Data System (ADS)

    Andrews, Joy Cooke

    1995-01-01

    In this study, oriented Photosystem II (PS II) particles from spinach chloroplasts are studied with electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy (XAS) to determine more details of the structure of the oxygen evolving complex (OEC). The nature of halide binding to Mn is also studied with Cl K-edge and Mn EXAFS (extended x-ray absorption fine structure) of Mn-Cl model compounds, and with Mn EXAFS of oriented PS II in which Br has replaced Cl. In chapter 2, oriented PS II particles from spinach were studied with EPR spectroscopy. The mosaic spread for these samples was determined by comparison of the oxidized cytochrome b_{559} (cyt b_{559}^+) signal measured at angles of 0^circ to 360^circ between the EPR magnetic field and sample membrane normal with simulations of oriented cyt b_{559}^+. The tyrosine Y_{rm D }^+ signal was measured for these oriented samples at 0^circ and 90 ^circ, and a linear relationship was found between the dichroism found in the tyrosine Y _{rm D}^+ signal and the mosaic spread. In chapters 3 and 4, Mn XAS was performed on oriented PS II membrane particles isolated from spinach. Structural features of the tetranuclear Mn cluster and the orientation of the cluster with respect to the lipid bilayer were determined in the S_2 state of the Kok cycle for control samples, and on the annealed S_2 state for the ammonia-treated samples. Variation of the sample orientation with respect to the x-ray e-vector yields highly dichroic EXAFS, indicative of an asymmetric tetranuclear cluster. Mn-Mn vectors at 2.72 A and 3.3 A are resolved from the control samples. Vectors at 2.73 A, 2.86 A and 3.3 A are resolved from the ammonia-treated samples. The 2.72 A vector for the control samples is oriented at an angle of 59^circ to the membrane normal (an average for at least two component vectors) with an average of 0.98 interaction per Mn atom. In the ammonia-treated samples it is further resolved into a 2.73 A vector at 54^circ and a 2.85 A vector at 61^circ. Thus, asymmetry of the two di-mu-oxo bridged Mn-Mn binuclear units of the OEC is directly observed. In chapter 5, the binding of halide to Mn was studied using Cl K-edge XAS and Mn EXAFS on Mn-Cl model compounds, and Mn EXAFS on oriented Br-treated PS II. From the Cl K-edges of model compounds, direct ligation of Cl to Mn could be confirmed with the presence of a pre-edge feature: a forbidden 1s to 3d transition which is seen due to mixing of Mn 3d orbitals with Cl 3p orbitals. Bridging and terminal Cl bonds to Mn could be distinguished. EXAFS of Mn-Cl model compounds revealed that Mn-Cl interactions, especially bridging interactions, make an important contribution to the EXAFS. (Abstract shortened by UMI.).

  15. Isolation and quantitation of. beta. -D-glucoNyranosyl abscisate from leaves of Xanthium and spinach

    SciTech Connect

    Boyer, G.L.; Zeevaart, J.A.D.

    1982-07-01

    Xanthium leaves are known to contain a high level of alkali-hydrolyzable conjugated abscisic acid. This abscisic acid conjugate has been isolated and identified by mass spectrometry, nuclear magnetic resonance, and chemical and enzymic degradation techniques, as the glucosyl ester of abscisic acid, ..beta..-D-glucopyranosyl abscisate. The glucosyl ester of abscisic acid was the only abscisic acid conjugate found in Xanthium leaves. It was also isolated from spinach leaves. An insignificant amount of the glucosyl ester of abscisic acid partitioned into diethyl ether, whereas 12% partitioned into ethyl acetate. Consequently, removal of absicsic acid by partitioning with ethyl acetate will result in considerable losses of the glucosyl ester of abscisic acid from the aqueous phase. Diethyl ether is, therefore, recommended for separation of abscisic acid and the glucosyl ester of abscisic acid by solvent partitioning. A method for quantitation of the glucosyl ester of abscisic acid as the tetraacetate derivative by gas-liquid chromatography with an electron capture detector was developed. The level of ..beta..-D-glycopyranosyl abscisate in Xanthium leaves increased from 3.6 nanomoles per gram fresh weight in turgid leaves to 22.9 nanomoles in leaves from plants subjected to seven wilting-recovery cycles. ..beta..-D-glycopyranosyl abscisate in Xanthium leaves may be a stable end product of abscisic acid metabolism.

  16. Crystallographic structure of the turbine C-ring from spinach chloroplast F-ATP synthase

    PubMed Central

    Balakrishna, Asha Manikkoth; Seelert, Holger; Marx, Sven-Hendric; Dencher, Norbert A.; Grüber, Gerhard

    2014-01-01

    In eukaryotic and prokaryotic cells, F-ATP synthases provide energy through the synthesis of ATP. The chloroplast F-ATP synthase (CF1FO-ATP synthase) of plants is integrated into the thylakoid membrane via its FO-domain subunits a, b, b’ and c. Subunit c with a stoichiometry of 14 and subunit a form the gate for H+-pumping, enabling the coupling of electrochemical energy with ATP synthesis in the F1 sector. Here we report the crystallization and structure determination of the c14-ring of subunit c of the CF1FO-ATP synthase from spinach chloroplasts. The crystals belonged to space group C2, with unit-cell parameters a=144.420, b=99.295, c=123.51 Å, and ?=104.34° and diffracted to 4.5 Å resolution. Each c-ring contains 14 monomers in the asymmetric unit. The length of the c-ring is 60.32 Å, with an outer ring diameter 52.30 Å and an inner ring width of 40 Å. PMID:24521269

  17. Efficient Photoelectrochemical Energy Conversion using Spinach Photosystem?II (PSII) in Lipid Multilayer Films.

    PubMed

    Zhang, Yun; Magdaong, Nikki M; Shen, Min; Frank, Harry A; Rusling, James F

    2015-04-01

    The need for clean, renewable energy has fostered research into photovoltaic alternatives to silicon solar cells. Pigment-protein complexes in green plants convert light energy into chemical potential using redox processes that produce molecular oxygen. Here, we report the first use of spinach protein photosystem?II (PSII) core complex in lipid films in photoelectrochemical devices. Photocurrents were generated from PSII in a ?2??m biomimetic dimyristoylphosphatidylcholine (DMPC) film on a pyrolytic graphite (PG) anode with PSII embedded in multiple lipid bilayers. The photocurrent was ?20??A?cm(-2) under light intensity 40?mW?cm(-2). The PSII-DMPC anode was used in a photobiofuel cell with a platinum black mesh cathode in perchloric acid solution to give an output voltage of 0.6?V and a maximum output power of 14??W?cm(-2). Part of this large output is related to a five-unit anode-cathode pH gradient. With catholytes at higher pH or no perchlorate, or using an MnO2 oxygen-reduction cathode, the power output was smaller. The results described raise the possibility of using PSII-DMPC films in small portable power conversion devices. PMID:25969807

  18. Efficient Photoelectrochemical Energy Conversion using Spinach Photosystem?II (PSII) in Lipid Multilayer Films

    PubMed Central

    Zhang, Yun; Magdaong, Nikki M; Shen, Min; Frank, Harry A; Rusling, James F

    2015-01-01

    The need for clean, renewable energy has fostered research into photovoltaic alternatives to silicon solar cells. Pigment–protein complexes in green plants convert light energy into chemical potential using redox processes that produce molecular oxygen. Here, we report the first use of spinach protein photosystem?II (PSII) core complex in lipid films in photoelectrochemical devices. Photocurrents were generated from PSII in a ?2??m biomimetic dimyristoylphosphatidylcholine (DMPC) film on a pyrolytic graphite (PG) anode with PSII embedded in multiple lipid bilayers. The photocurrent was ?20??A?cm?2 under light intensity 40?mW?cm?2. The PSII–DMPC anode was used in a photobiofuel cell with a platinum black mesh cathode in perchloric acid solution to give an output voltage of 0.6?V and a maximum output power of 14??W?cm?2. Part of this large output is related to a five-unit anode–cathode pH gradient. With catholytes at higher pH or no perchlorate, or using an MnO2 oxygen-reduction cathode, the power output was smaller. The results described raise the possibility of using PSII–DMPC films in small portable power conversion devices. PMID:25969807

  19. Spinach thylakoid polyphenol oxidase isolation, activation, and properties of the native chloroplast enzyme

    SciTech Connect

    Golbeck, J.H.; Cammarata, K.V.

    1981-05-01

    Polyphenol oxidase activity (E.C. 1.14,18.1) has been found in two enzyme species isolated from thylakoid membranes of spinach chloroplasts. The proteins were released from the membrane by sonication and purified >900-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzymes appear to be the tetramer and monomer of a subunit with a molecular weight of 42,500 as determined by lithium dodecyl sulfate gel electrophoresis. Sonication releases polyphenol oxidase from the membrane largely in the latent state. In the absence of added fatty acids, the isolated enzyme spontaneously, but slowly, activates with time. Purified polyphenol oxidase utilizes o-diphenols as substrates and shows no detectable levels of monophenol or p-diphenol oxidase activities. Suitable substrates include chlorogenic acid, catechol, caffeic acid, pyrogallol, and dopamine; however, the enzyme is substrate-inhibited by the last four at concentrations near their K/sub m/. A large seasonal variation in polyphenol oxidase activity may result from a decrease in enzyme content rather than inhibition of the enzyme present.

  20. Crystallographic structure of the turbine c-ring from spinach chloroplast F-ATP synthase.

    PubMed

    Balakrishna, Asha Manikkoth; Seelert, Holger; Marx, Sven-Hendric; Dencher, Norbert A; Grüber, Gerhard

    2014-02-13

    In eukaryotic- and prokaryotic cells F-ATP synthases provide energy through the synthesis of adenosine triphosphate (ATP). The chloroplast F-ATP synthase (CF1FO-ATP synthase) of plants is integrated into the thylakoid membrane via its FO-domain subunits a, b, b' and c. Subunit c with a stoichiometry of 14 and subunit a form the gate for H+-pumping, enabling the coupling of electrochemical energy with ATP synthesis in the F1 sector. Here we report the crystallization and structure determination of the c14-ring of subunit c of the CF1FO-ATP synthase from spinach chloroplasts. The crystals belonged to space group C2, with unit-cell parameters a = 144.420, b = 99.295, c = 123.51 Å, and ? = 104.34º and diffracted to 4.5 Å resolution. Each c-ring contains fourteen monomers in the asymmetric unit. The length of the c-ring is 60.32 Å, with an outer ring diameter 52.30 Å, and an inner ring width of 40 Å. PMID:24521269

  1. Effects of Temperature Pretreatment in the Dark on Photosynthesis of the Intact Spinach Chloroplast 1

    PubMed Central

    Fu, Chee Fook; Gibbs, Martin

    1988-01-01

    Isolated, intact spinach (Spinacia oleracea L. var. “Long Standing Bloomsdale”) chloroplasts were heated in the dark and the effect of this treatment on photosynthetic activities was determined at 25°C. Dark incubation of the chloroplasts for 10 minutes at 35°C and pH 8.1 resulted in a 50% decline in CO2 photoassimilation. This decline in photosynthetic performance was dependent upon time, temperature, and medium pH with the optimum effect at acidic pH values. Photosynthetic decline was not observed if MgATP, MgADP, or a mixture of fructose 1,6-bisphosphate, aldolase, and oxaloacetate or ribose 5-phosphate and oxaloacetate was added prior to but not after the temperature pretreatment. A chloroplast preparation reconstituted with thylakoids and stroma from pretreated (35°C, 10 minutes, pH 8.1) intact chloroplasts and supplemented with ferredoxin, ADP, and NADP was photosynthetically competent, indicating that ATP-coupled electron flow and the enzymes comprising the Benson-Calvin cycle remained stable during the dark treatment. In contrast, exposure of isolated thylakoids to 35°C for 10 minutes uncoupled photophosphorylation from NADP and ferricyanide reduction. We propose that the decline of intact chloroplast photosynthesis is the result of a decrease in the content of or a change in the ratios of the adenine nucleotides. Maintenance of an adequate supply of adenine nucleotide is the effect of the externally added MgATP or of chloroplastic respiration of a sugar phosphate. PMID:16666267

  2. Spinach Leaves Desaturate Exogenous [14C]Palmitate to Hexadecatrienoate 1

    PubMed Central

    Thompson, Guy A.; Roughan, P. Grattan; Browse, John A.; Slack, C. Roger; Gardiner, Susan E.

    1986-01-01

    Long-chain 14C-fatty acids applied to the surface of expanding spinach leaves were incorporated into all major lipid classes. When applied in diethyleneglycol monomethyl ether solution, as done by previous workers, [14C]palmitic acid uptake was much lower than that of [14C] oleic acid. However, when applied in a thin film of liquid paraffin the rate of [14C] palmitic acid metabolism was rapid and virtually complete. Considerable radioactivity from [14C]palmitate incorporated into lipids following either application method gradually appeared in polyunsaturated C16 fatty acids esterified to those molecular species of galactolipids previously thought to be made using only fatty acids synthesized and retained within the chloroplast. Evidence for the incorporation of radioactivity from exogenous [14C]oleate into those same molecular species of galactolipids was less compelling. The unexpected availability of fatty acids bound to extrachloroplastidal lipids for incorporation into galactolipids characteristically assembled entirely within the chloroplast emphasizes the need to reassess interrelations between the “prokaryotic” and “eukaryotic” pathways of galactolipid formation. PMID:16665035

  3. 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.

  4. The Food Matrix of Spinach Is a Limiting Factor in Determining the Bioavailability of b-Carotene and to a Lesser Extent of Lutein in Humans1,2

    Microsoft Academic Search

    Jacqueline J. M. Castenmiller; Clive E. West; Jozef P. H. Linssen; Alphons G. J. Voragen

    Carotenoid bioavailability depends, amongst other factors, on the food matrix and on the type and extent of processing. To examine the effect of variously processed spinach products and of dietary fiber on serum carotenoid concentrations, subjects received, over a 3-wk period, a control diet (n 5 10) or a control diet supplemented with carotenoids or one of four spinach products

  5. Leaf-to-leaf distances in Catalan tree graphs

    E-print Network

    Andrew M. Goldsborough; Jonathan M. Fellows; Matthew Bates; S. Alex Rautu; George Rowlands; Rudolf A. Römer

    2015-03-02

    We study the average leaf-to-leaf path lengths on ordered Catalan tree graphs with $n$ nodes and show that these are equivalent to the average length of paths starting from the root node. We give an explicit analytic formula for the average leaf-to-leaf path length as a function of separation of the leaves and study its asymptotic properties. At the heart of our method is a strategy based on an abstract graph representation of generating functions which we hope can be useful also in other contexts.

  6. Chloroplast volume: cell water potential relationships and acclimation of photosynthesis to leaf water deficits.

    PubMed

    Santakumari, M; Berkowitz, G A

    1991-04-01

    Studies were undertaken to determine if there is an association between nonstomatally-mediated acclimation of photosynthesis to low water potential (?w) and the maintenance of chloroplast volume during water stress. Spinach plants either kept well watered throughout their growth (non-acclimated), or subjected to water stress such that leaf ?w dropped to -1.5 megapascals (MPa) and then were rewatered (acclimated) were subjected to drought episodes. During these stress periods, photosynthesis was maintained to a greater extent in acclimated plants as compared to non-acclimated plants at ?w below -1 MPa.Estimates of internal leaf [CO2] suggested that photosynthetic acclimation to low ?w was not primarily due to altered stomatal response. As ?w dropped from initial values, a decline in steady state levels of ribulose 1,5-bisphosphate (RuBP) occurred in both non-acclimated and acclimated plants. RuBP decline was less severe in acclimated plants.Low ?w effects on chloroplast volume in non-acclimated and acclimated plants were estimated by measuring the volume of intact chloroplasts isolated from plants in solutions which were made isotonic to declining leaf osmotic potential during the drought episodes. Chloroplast volume was maintained to a greater extent at low ?w in acclimated, as compared with non-acclimated plants. Although substantial osmotic adjustment occurred in both non-acclimated and acclimated plants, the extent of osmotic adjustment was the same. These data were interpreted as supporting the hypothesis that cellular-level acclimation to low ?w is associated with chloroplast volume maintenance, and this physiological acclimation is correlated with enhanced photosynthetic capacity of the leaf at low ?w. PMID:24414794

  7. Modeling of the redox state dynamics in photosystem II of Chlorella pyrenoidosa Chick cells and leaves of spinach and Arabidopsis thaliana from single flash-induced fluorescence quantum yield changes on the 100 ns-10 s time scale.

    PubMed

    Belyaeva, N E; Schmitt, F-J; Paschenko, V Z; Riznichenko, G Yu; Rubin, A B

    2015-08-01

    The time courses of the photosystem II (PSII) redox states were analyzed with a model scheme supposing a fraction of 11-25 % semiquinone (with reduced [Formula: see text]) RCs in the dark. Patterns of single flash-induced transient fluorescence yield (SFITFY) measured for leaves (spinach and Arabidopsis (A.) thaliana) and the thermophilic alga Chlorella (C.) pyrenoidosa Chick (Steffen et al. Biochemistry 44:3123-3132, 2005; Belyaeva et al. Photosynth Res 98:105-119, 2008, Plant Physiol Biochem 77:49-59, 2014) were fitted with the PSII model. The simulations show that at high-light conditions the flash generated triplet carotenoid (3)Car(t) population is the main NPQ regulator decaying in the time interval of 6-8 ?s. So the SFITFY increase up to the maximum level [Formula: see text]/F 0 (at ~50 ?s) depends mainly on the flash energy. Transient electron redistributions on the RC redox cofactors were displayed to explain the SFITFY measured by weak light pulses during the PSII relaxation by electron transfer (ET) steps and coupled proton transfer on both the donor and the acceptor side of the PSII. The contribution of non-radiative charge recombination was taken into account. Analytical expressions for the laser flash, the (3)Car(t) decay and the work of the water-oxidizing complex (WOC) were used to improve the modeled P680(+) reduction by YZ in the state S 1 of the WOC. All parameter values were compared between spinach, A. thaliana leaves and C. pyrenoidosa alga cells and at different laser flash energies. ET from [Formula: see text] slower in alga as compared to leaf samples was elucidated by the dynamics of [Formula: see text] fractions to fit SFITFY data. Low membrane energization after the 10 ns single turnover flash was modeled: the ??(t) amplitude (20 mV) is found to be about 5-fold smaller than under the continuous light induction; the time-independent lumen pHL, stroma pHS are fitted close to dark estimates. Depending on the flash energy used at 1.4, 4, 100 % the pHS in stroma is fitted to 7.3, 7.4, and 7.7, respectively. The biggest ?pH difference between stroma and lumen was found to be 1.2, thus pH- dependent NPQ was not considered. PMID:26049407

  8. Calcium oxalate nephrolithiasis and tubular necrosis in recent metamorphs of Rana sylvatica (Lithobates sylvaticus) fed spinach during the premetamorphic (tadpole) stage.

    PubMed

    Forzán, M J; Ferguson, L V; Smith, T G

    2015-03-01

    Amphibians in the family Ranidae (true frogs) seem highly susceptible to oxalosis, particularly when fed a diet high in oxalic acid during the premetamorphic (tadpole) stage. The authors describe the mortality of 150 captive-raised wood frogs (Rana sylvatica or Lithobates sylvaticus) from oxalate nephrolithiasis and renal tubular necrosis caused by consumption of boiled spinach during tadpole development. Renal lesions were due to intraluminal transparent crystals which were birefringent under polarized light and were identified morphologically and histochemically as composed of calcium oxalate. Evidence of early fibrosis or squamous metaplasia, and a presentation at least 2 weeks after spinach consumption had ended, suggested a subacute course. Tadpole-feeding protocols should avoid plants with high oxalate content (eg, spinach and rhubarb leaves), and any episode of high mortality in captive amphibians along with nephrolithiasis should prompt an evaluation of the feed sources for material with high oxalate content. PMID:24823808

  9. Effect of aerobic and anaerobic conditions on the in vivo nitrate reductase assay in spinach leaves

    Microsoft Academic Search

    A. F. Mann; D. P. Hucklesby; E. J. Hewitt

    1979-01-01

    15N-labelled nitrate was used to show that nitrate reduction by leaf discs in darkness was suppressed by oxygen, whereas nitrite present within the cell could be reduced under aerobic dark conditions. In other experiments, unlabelled nitrite, allowed to accumulate in the tissue during the dark anaerobic reduction of nitrate was shown by chemical analysis to be metabolised during a subsequent

  10. 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

  11. Element concentrations in water spinach (Ipomoea aquatica Forssk.), fish and sediment from a wetland production system that receives wastewater from Phnom Penh, Cambodia.

    PubMed

    Marcussen, Helle; Dalsgaard, Anders; Holm, Peter E

    2009-01-01

    The Cheung Ek Lake, which is located south of Phnom Penh, Cambodia, receives most of the industrial and domestic wastewater that is produced in the city. The lake is used for fishing and production of water spinach (Ipomoea aquatica Forssk). Concentrations of 35 elements were determined in water spinach and sediment that were collected along transects of two wastewater inlets in the lake, at the lake outlet, and in a non-wastewater exposed pond. Elevated concentrations of the potentially toxic elements (PTEs) Cd, Cu, Ni, Pb, Sb, and Zn were found in the water spinach and sediment samples collected near the wastewater inlets. The highest determined PTE concentrations in water spinach were, in mg kg(- 1) fresh weight (f.w.), As 0.19, Cd 0.022, Cu 2.95, Fe 251, Pb 0.206 and Zn 9.08. For an adult person in Phnom Penh, the maximum intake of PTEs from consumption of water spinach harvested near the wastewater inlets amounts to 5.7% As, 1.4% Cd, 0.4% Cu, 20.5% Fe, 3.8% Pb and 0.6% Zn of the maximum tolerable intake set by the Codex Alimentarious Commission. Arsenic, Cd and Pb concentrations in the liver, skin, and muscle of three fish species caught in the lake were below or near the detection limits, except for a high accumulation of the three elements in the skin of the blackskin catfish. In conclusion, the consumption of water spinach and fish from Cheung Ek Lake constitutes a low food safety risk with respect to PTEs. PMID:19085597

  12. [Chemical characteristics of the rhizosphere soil of water spinach cultivars differing in Cd accumulation].

    PubMed

    Gong, Yu-Lian; Yang, Zhong-Yi

    2014-08-01

    A rhizobox experiment was conducted to investigate the chemical characteristics of the rhizosphere soils of two water spinach cultivars differing in Cd accumulation, QLQ (a low-Cd cultivar) and T308 (a high-Cd cultivar). The results showed that the diethylenetriamine pentacetate acid extractable Cd (DTPA-Cd) concentration in the rhizos-phere soil of QLQ was significantly higher than that of T308 (P < 0.05). pH and Eh in the rhizosphere soil of QLQ were significantly higher than those of T308 (P < 0.05), while EC was opposite. Contents of organic matter and dissolved organic matter (DOM) in the rhizosphere soil of QLQ were both higher than those of T308. In contaminated soil, the composition and concentration of low molecular weight organic acids in the rhizosphere between the two cultivars were both different. Acetic, propionic, citric and fumaric acids were detected in the rhizosphere soil of T308, and only citric and fumaric acids were detected in that of QLQ. The total concentration of low molecular weight organic acids in the rhizosphere soil of QLQ (1.93 nmol x g(-1) DM) was lower than that of T308 (15.11 nmol x g(-1) DM) (P < 0.01). Compared with the high-Cd cultivar (T308), the chemical characteristics of the rhizosphere soil of the low-Cd cultivar (QLQ) were obviously distinct, i. e., the relatively higher content of organic matter, the lower content of low molecular weight organic acids with a specific composition, less acidification of soil, and a lower ability in reduction, correspondingly lowering the mobility of Cd in soil and reducing Cd accumulation by plant. PMID:25509092

  13. Analysis of the oxidation-reduction potentials of recombinant ferredoxin-NADP+ reductase from spinach chloroplasts.

    PubMed

    Corrado, M E; Aliverti, A; Zanetti, G; Mayhew, S G

    1996-08-01

    Midpoint oxidation-reduction potentials for the two-electron reduction of the bound FAD in spinach ferredoxin-NADP+ reductase were measured by potentiometry (Em = -342 +/- 1 mV at pH 7 and 10 degrees C). They were used with the semiquinone formation constant, obtained by spectroscopic measurement of the semiquinone concentration, to calculate values for the redox potentials of the two one-electron steps in the reduction. The redox potential for the oxidized enzyme/enzyme semiquinone couple (EOX/SQ) at pH 7 is -350 +/- 2 mV (10 degrees C) while the value for the enzyme semiquinone/enzyme hydroquinone couple (ESQ/HQ) under the same conditions is -335 +/- 1 mV. These values correspond to a semiquinone formation constant of 0.55. Measurement of the effects of pH on the potentials showed that EOX/SQ varies linearly with pH (slope -46 +/- 4 mV), while ESQ/HQ is independent of pH at high pH values, but below about pH 7.5 the potential becomes less negative with decreasing pH. indicating that there is a redox-linked protonation of the fully reduced enzyme (pKa = 7.2, 10 degrees C). The absorption spectrum of the fully reduced enzyme was found to depend on pH with the changes giving a calculated pKa of 7.5 (at 15 degrees C). The spectrum at high pH is similar to that of the anionic form of free flavin hydroquinone. The observations suggest that at physiological pH, the enzyme FAD cycles between the three redox states: oxidized, neutral semiquinone and hydroquinone anion. PMID:8774710

  14. Combining Leaf Salient Points and Leaf Contour Descriptions for Plant Species Recognition

    E-print Network

    Verroust-Blondet, Anne

    Combining Leaf Salient Points and Leaf Contour Descriptions for Plant Species Recognition Sofiene for plant species recognition, based on the leaf observation. We consider two sources of information: the leaf margin and the leaf salient points. For the leaf shape description, we investigate the shape

  15. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture...INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

  16. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2 2014-01-01 2014-01-01 false Leaf structure. 29.6023 Section 29.6023...INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its porosity. The degrees...

  17. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  18. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  19. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture...INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

  20. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  1. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture...INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

  2. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2 2012-01-01 2012-01-01 false Leaf structure. 29.6023 Section 29.6023...INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its porosity. The degrees...

  3. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2 2013-01-01 2013-01-01 false Leaf structure. 29.6023 Section 29.6023...INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its porosity. The degrees...

  4. 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 corner-sharing, head-to-tail dimer. The ability to perform the oxygen-evolving reaction in water at neutral or near-neutral conditions has several consequences for the construction of the artificial leaf. The NiMoZn alloy may be used in place of Pt to generate hydrogen. To stabilize silicon in water, its surface is coated with a conducting metal oxide onto which the Co-OEC may be deposited. The net result is that immersing a triple-junction Si wafer coated with NiMoZn and Co-OEC in water and holding it up to sunlight can effect direct solar energy conversion via water splitting. By constructing a simple, stand-alone device composed of earth-abundant materials, the artificial leaf provides a means for an inexpensive and highly distributed solar-to-fuels system that employs low-cost systems engineering and manufacturing. Through this type of system, solar energy can become a viable energy supply to those in the non-legacy world. PMID:22475039

  5. The worldwide leaf economics spectrum

    Microsoft Academic Search

    Ian J. Wright; Peter B. Reich; Mark Westoby; David D. Ackerly; Zdravko Baruch; Frans Bongers; Jeannine Cavender-Bares; Terry Chapin; Johannes H. C. Cornelissen; Matthias Diemer; Jaume Flexas; Eric Garnier; Philip K. Groom; Javier Gulias; Kouki Hikosaka; Byron B. Lamont; Tali Lee; William Lee; Christopher Lusk; Jeremy J. Midgley; Marie-Laure Navas; Ülo Niinemets; Jacek Oleksyn; Noriyuki Osada; Pieter Poot; Lynda Prior; Vladimir I. Pyankov; Catherine Roumet; Sean C. Thomas; Mark G. Tjoelker; Erik J. Veneklaas; Rafael Villar

    2004-01-01

    Bringing together leaf trait data spanning 2,548 species and 175 sites we describe, for the first time at global scale, a universal spectrum of leaf economics consisting of key chemical, structural and physiological properties. The spectrum runs from quick to slow return on investments of nutrients and dry mass in leaves, and operates largely independently of growth form, plant functional

  6. Automatic detection of regions in spinach canopies responding to soil moisture deficit using combined visible and thermal imagery.

    PubMed

    Raza, Shan-e-Ahmed; Smith, Hazel K; Clarkson, Graham J J; Taylor, Gail; Thompson, Andrew J; Clarkson, John; Rajpoot, Nasir M

    2014-01-01

    Thermal imaging has been used in the past for remote detection of regions of canopy showing symptoms of stress, including water deficit stress. Stress indices derived from thermal images have been used as an indicator of canopy water status, but these depend on the choice of reference surfaces and environmental conditions and can be confounded by variations in complex canopy structure. Therefore, in this work, instead of using stress indices, information from thermal and visible light imagery was combined along with machine learning techniques to identify regions of canopy showing a response to soil water deficit. Thermal and visible light images of a spinach canopy with different levels of soil moisture were captured. Statistical measurements from these images were extracted and used to classify between canopies growing in well-watered soil or under soil moisture deficit using Support Vector Machines (SVM) and Gaussian Processes Classifier (GPC) and a combination of both the classifiers. The classification results show a high correlation with soil moisture. We demonstrate that regions of a spinach crop responding to soil water deficit can be identified by using machine learning techniques with a high accuracy of 97%. This method could, in principle, be applied to any crop at a range of scales. PMID:24892284

  7. Synthesis of thylakoid membrane proteins by chloroplasts isolated from spinach. Cytochrome b559 and P700-chlorophyll a-protein

    PubMed Central

    1980-01-01

    Intact chloroplasts, purified from spinach leaves by sedimentation in density gradients of colloidal silica, incorporate labeled amino acids into at least 16 different polypeptides of the thylakoid membranes, using light as the only source of energy. The thylakoid products of chloroplast translation were visualized by subjecting membranes purified from chloroplasts labeled with [35S]methionine to electrophoresis in high-resolution, SDS-containing acrylamide gradient slab gels and autoradiography. The apparent mol wt of the labeled products ranged from less than 10,000 to greater than 70,000. One of the labeled products is the apoprotein of the P700-chlorophyll a- protein (CPI). The CPI apoprotein is assembled into a pigment-protein complex which is electrophoretically indistinguishable from the native CPI complex. Isolated spinach chloroplasts also incorporate [3H]leucine and [35S]methionine into cytochrome b559. The radioactive label remains with the cytochrome through all stages of purification: extraction of the thylakoid membranes with Triton X-100 and urea, adsorption of impurities on DEAE cellulose, two cycles of electrophoresis in Triton- containing polyacrylamide gels and electrophoresis in SDS-containing gradient gels. Cytochrome b559 becomes labeled with both [3H]leucine and [35S]methionine and accounts for somewhat less than 1% of the total isotopic incorporation into thylakoid protein. The lipoprotein appears to be fully assembled during the time-course of our labeling experiments. PMID:7372715

  8. Automatic Detection of Regions in Spinach Canopies Responding to Soil Moisture Deficit Using Combined Visible and Thermal Imagery

    PubMed Central

    Raza, Shan-e-Ahmed; Smith, Hazel K.; Clarkson, Graham J. J.; Taylor, Gail; Thompson, Andrew J.; Clarkson, John; Rajpoot, Nasir M.

    2014-01-01

    Thermal imaging has been used in the past for remote detection of regions of canopy showing symptoms of stress, including water deficit stress. Stress indices derived from thermal images have been used as an indicator of canopy water status, but these depend on the choice of reference surfaces and environmental conditions and can be confounded by variations in complex canopy structure. Therefore, in this work, instead of using stress indices, information from thermal and visible light imagery was combined along with machine learning techniques to identify regions of canopy showing a response to soil water deficit. Thermal and visible light images of a spinach canopy with different levels of soil moisture were captured. Statistical measurements from these images were extracted and used to classify between canopies growing in well-watered soil or under soil moisture deficit using Support Vector Machines (SVM) and Gaussian Processes Classifier (GPC) and a combination of both the classifiers. The classification results show a high correlation with soil moisture. We demonstrate that regions of a spinach crop responding to soil water deficit can be identified by using machine learning techniques with a high accuracy of 97%. This method could, in principle, be applied to any crop at a range of scales. PMID:24892284

  9. [Fast separation and analysis of water-soluble vitamins in spinach by capillary electrophoresis with high voltage].

    PubMed

    Hu, Xiaoqin; You, Huiyan

    2009-11-01

    In capillary electrophoresis, 0-40 kV (even higher) voltage can be reached by a connecting double-model high voltage power supply. In the article, water-soluble vitamins, VB1, VB2, VB6, VC, calcium D-pantothenate, D-biotin, nicotinic acid and folic acid in vegetable, were separated by using the high voltage power supply under the condition of electrolyte water solution as running buffer. The separation conditions, such as voltage, the concentration of buffer and pH value etc. , were optimized during the experiments. The results showed that eight water-soluble vitamins could be baseline separated in 2.2 min at 40 kV applied voltage, 25 mmol/L sodium tetraborate buffer solution (pH 8.8). The water-soluble vitamins in spinach were quantified and the results were satisfied. The linear correlation coefficients of the water-soluble vitamins ranged from 0.9981 to 0.9999. The detection limits ranged from 0.2 to 0.3 mg/L. The average recoveries ranged from 88.0% to 100.6% with the relative standard deviations (RSD) range of 1.15%-4.13% for the spinach samples. PMID:20352941

  10. Isolation of Campylobacter from feral swine (Sus scrofa) on the ranch associated with the 2006 Escherichia coli O157:H7 spinach outbreak investigation in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We report the isolation of Campylobacter species from the same population of feral swine that was investigated in San Benito County, California during the 2006 spinach-related Escherichia coli O157:H7 outbreak. This is the first survey of Campylobacter in a free-ranging feral swine population in the...

  11. The Effect of Repeated Irrigation with Water Containing Varying Levels of Total Organic Carbon on the Persistence of Escherichia coli O157:H7 on Baby Spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The California lettuce and leafy greens industry has adopted the Leafy Greens Marketing Agreement (LGMA), which allows for 126 Most Probable Number (MPN) generic E. coli/100ml in irrigation water. Repeat irrigation of baby spinach plants with water containing E. coli O157:H7 and different levels of...

  12. Ribulose1,5-bisphosphate carboxylase-oxygenase, other Calvin-cycle enzymes, and chlorophyll decrease when glucose is supplied to mature spinach leaves via the transpiration stream

    Microsoft Academic Search

    Anne Krapp; W. Paul Quick; Mark Stitt

    1991-01-01

    The inhibition of photosynthesis after supplying glucose to detached leaves of spinach (Spinacia oleracea L.) was used as a model system to search for mechanisms which potentially contribute to the “sink” regulation of photosynthesis. Detached leaves were supplied with 50 mM glucose or water for 7 d through the transpiration stream, holding the leaves in low irradiance (16 µmol photons

  13. The effect of total organic carbon content and repeated irrigation on the persistence of E. coli O157:H7 on baby spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Contaminated fresh-cut spinach and other leafy greens have caused foodborne illness in the United States. In response, growers are adopting recommendations stated in the California Leafy Greens Marketing Agreement (LGMA). The LGMA permits a maximum population of 126 Most Probable Nu...

  14. Use of zero-valent iron biosand filters to reduce E. coli O157:H12 in irrigation water applied to spinach plants in a field setting

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Zero-valent iron (ZVI) filters may provide an efficient method to mitigate the contamination of produce crops through irrigation water. Purpose: To evaluate the use of ZVI-filtration in decontaminating E. coli O157:H12 in irrigation water and on spinach plants in a small, field-scale...

  15. Inhibition of E. coli O157:H7 on the surface of Fresh Spinach by bacteriophage ECP-100 and Modified Atmosphere Packaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The last multistate Escherichia coli O157:H7 (EHEC) outbreak linked to bagged spinach in 2006 has raised concerns about the safety of ready-to-eat vegetables. Since washing alone or in combination with chemicals has been ineffective in completely killing EHEC, there is an urgent need for more effect...

  16. Effect of gamma radiation on the reduction of Salmonella strains, Listeria monocytogenes, and Shiga toxin-producing Escherichia coli and sensory evaluation of minimally processed spinach (Tetragonia expansa).

    PubMed

    Rezende, Ana Carolina B; Igarashi, Maria Crystina; Destro, Maria Teresa; Franco, Bernadette D G M; Landgraf, Mariza

    2014-10-01

    This study evaluated the effects of irradiation on the reduction of Shiga toxin-producing Escherichia coli (STEC), Salmonella strains, and Listeria monocytogenes, as well as on the sensory characteristics of minimally processed spinach. Spinach samples were inoculated with a cocktail of three strains each of STEC, Salmonella strains, and L. monocytogenes, separately, and were exposed to gamma radiation doses of 0, 0.2, 0.4, 0.6, 0.8, and 1.0 kGy. Samples that were exposed to 0.0, 1.0, and 1.5 kGy and kept under refrigeration (4°C) for 12 days were submitted to sensory analysis. D10 -values ranged from 0.19 to 0.20 kGy for Salmonella and from 0.20 to 0.21 for L. monocytogenes; for STEC, the value was 0.17 kGy. Spinach showed good acceptability, even after exposure to 1.5 kGy. Because gamma radiation reduced the selected pathogens without causing significant changes in the quality of spinach leaves, it may be a useful method to improve safety in the fresh produce industry. PMID:25285495

  17. A novel approach to investigate the uptake and internalization of Escherichia coli O157:H7 in spinach cultivated in soil and hydroponic media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Internalization of E. coli O157:H7 into spinach plants through root uptake is a potential route of contamination. A Tn7-based plasmid vector was used to insert the green fluorescent protein (gfp) gene into the attTn7 site in the E. coli chromosome. Three gfp-labeled E. coli inocula, O157:H7 strains ...

  18. 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

  19. Escherichia coli O157:H7 biofilm formation and internalization on lettuce and spinach leaf surfaces reduces efficacy of irradiation and sodium hypochlorite washes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Escherichia coli O157:H7 contamination of leafy green vegetables is an ongoing concern for consumers. Biofilm-associated and internalized pathogens are relatively resistant to chemical treatments, but little is known about the response of these protected pathogens to irradiation. Leaves of Romaine l...

  20. Phenolic profile evolution of different ready-to-eat baby-leaf vegetables during storage.

    PubMed

    Santos, J; Oliveira, M B P P; Ibáñez, E; Herrero, M

    2014-01-31

    Ready-to-eat baby-leaf vegetables market has been growing and offering to consumers convenient, healthy and appealing products, which may contain interesting bioactive compounds. In this work, the composition and the evolution of the phenolic compounds from different baby-leaf vegetables during refrigerated storage was studied. The phenolic compounds were extracted using pressurized liquid extraction (PLE) and the phenolic profile of each sample was analyzed and quantified by using LC-MS and LC-DAD methods, respectively, at the beginning and at the end of a 10-day storage period. The baby-leaf vegetables studied included green lettuce, ruby red lettuce, swiss chard, spinach, pea shoots, watercress, garden cress, mizuna, red mustard, wild rocket and spearmint samples and a total of 203 phenolic compounds were tentatively identified and quantified. The main naturally phenolic compounds identified correspond to glycosylated flavonoids, with exception of green lettuce and spearmint leaves which had a higher content of hydroxycinnamic acids. Quantification of the main compounds showed a 10-fold higher content of total phenolic content of ruby red lettuce (483mgg(-1)) in relation to the other samples, being the lowest values found in the garden cress (12.8mgg(-1)) and wild rocket leaves (8.1mgg(-1)). The total phenolic content only showed a significant change (p<0.05) after storage in the green lettuce (+17.5%), mizuna (+7.8%), red mustard (-23.7%) and spearmint (-13.8%) leaves. Within the different classes of phenolic compounds monitored, the flavonols showed more stable contents than the hydroxycinnamic and hydroxybenzoic acids, although the behavior of each compound varied strongly among samples. PMID:24438834

  1. Prediction of protein targets of kinetin using in silico and in vitro methods: a case study on spinach seed germination mechanism.

    PubMed

    Kumar, Sivakumar Prasanth; Parmar, Vilas R; Jasrai, Yogesh T; Pandya, Himanshu A

    2015-07-01

    Kinetin, a cytokinin which promotes seed germination by inhibiting the action of abscisic acid, is an important molecule known to trigger various molecular mechanisms by interacting with an array of proteins shown from experimental observations in various model organisms. We report here the prediction of most probable protein targets of kinetin from spinach proteome using in silico approaches. Inverse docking and ligand-based similarity search was performed using kinetin as molecule. The former method prioritized six spinach proteins, whereas the latter method provided a list of protein targets retrieved from several model organisms. The most probable protein targets were selected by comparing the rank list of docking and ligand similarity methods. Both of these methods prioritized chitinase as the most probable protein target (?G pred?=?5.064 kcal/mol) supported by the experimental structure of yeast chitinase 1 complex with kinetin (PDB: 2UY5) and Gliocladium roseum chitinase complex with 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione (caffeine; 3G6M) which bears a 3D similarity of 0.43 with kinetin. An in vitro study to evaluate the effect of kinetin on spinach seed germination indicated that a very low concentration of kinetin (0.5 mg/l) did not show a significant effect compared to control in inducing seed germination process. Further, higher levels of kinetin (>0.5 mg/l) constituted an antagonist effect on spinach seed germination. It is anticipated that kinetin may have a molecular interaction with prioritized protein targets synthesized during the seed germination process and reduces growth. Thus, it appears that kinetin may not be a suitable hormone for enhancing spinach seed germination in vitro. PMID:26101551

  2. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture...12, 13, 14 and Foreign Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  3. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture...Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  4. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Leaf surface. 29.3036 Section 29...and Foreign Type 93) § 29.3036 Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

  5. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Leaf surface. 29.3036 Section 29...and Foreign Type 93) § 29.3036 Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

  6. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture...12, 13, 14 and Foreign Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  7. Very Sparse Leaf Languages Lance Fortnow

    E-print Network

    Fortnow, Lance

    Very Sparse Leaf Languages Lance Fortnow Department of Computer Science University of Chicago studied the balanced leaf languages defined via poly-logarithmically sparse leaf pattern sets. Unger shows that NP-complete sets are not polynomial-time many-one reducible to such balanced leaf language unless

  8. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Leaf surface. 29.3528 Section 29...and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to some...

  9. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture...s. Type 31 and Foreign Type 93) § 29.3033 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  10. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Leaf surface. 29.3036 Section 29...and Foreign Type 93) § 29.3036 Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

  11. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture...s. Type 31 and Foreign Type 93) § 29.3033 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  12. Very Sparse Leaf Languages # Lance Fortnow +

    E-print Network

    Fortnow, Lance

    Very Sparse Leaf Languages # Lance Fortnow + Department of Computer Science University of Chicago studied the balanced leaf languages defined via poly­logarithmically sparse leaf pattern sets. Unger shows that NP­complete sets are not polynomial­time many­one reducible to such balanced leaf language unless

  13. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture...35, 36, 37 and Foreign Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  14. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture...s. Type 31 and Foreign Type 93) § 29.3033 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  15. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture...Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  16. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Agriculture 2 2014-01-01 2014-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture...Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  17. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture...12, 13, 14 and Foreign Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  18. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture...35, 36, 37 and Foreign Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  19. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Leaf surface. 29.3528 Section 29...and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to some...

  20. 7 CFR 29.3528 - Leaf surface.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Leaf surface. 29.3528 Section 29...and Foreign Type 95) § 29.3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to some...

  1. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture...35, 36, 37 and Foreign Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

  2. 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 (??stem–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 ??stem–leaf. This enables leaves to minimize variation in ?leaf and maximize g s and CO2 assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  3. PLANT SPECIES RECOGNITION USING SPATIAL CORRELATION BETWEEN THE LEAF MARGIN AND THE LEAF SALIENT POINTS

    E-print Network

    Paris-Sud XI, Université de

    PLANT SPECIES RECOGNITION USING SPATIAL CORRELATION BETWEEN THE LEAF MARGIN AND THE LEAF SALIENT by the plant leaves. More precisely, we consider two sources of information: the leaf margin and the leaf salient points. We investigate two shape context based descriptors: the first one describes the leaf

  4. Leaf-wax n-alkanes record the plantwater environment at leaf ush

    E-print Network

    Tipple, Brett

    Leaf-wax n-alkanes record the plant­water environment at leaf ush Brett J. Tipple1 , Melissa A, UT, and approved December 26, 2012 (received for review August 13, 2012) Leaf-wax n-alkanes 2 H/1 H the 2 H values of leaf-wax n-alkanes and of stem, leaf, stream, and atmospheric waters throughout

  5. 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 (??stem-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 CO? 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 CO? 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 CO? on g s. The positive relationship between k leaf and E minimized variation in ??stem-leaf. This enables leaves to minimize variation in ?leaf and maximize g s and CO? assimilation rate over the diurnal course of evaporative demand. PMID:25547915

  6. Changes in leaf hydraulic conductance correlate with leaf vein embolism in Cercis siliquastrum L

    Microsoft Academic Search

    Andrea Nardini; Sebastiano Salleo; Fabio Raimondo

    2003-01-01

    The impact of xylem cavitation and embolism on leaf ( K leaf) and stem ( K stem) hydraulic conductance was measured in current-year shoots of Cercis siliquastrum L. (Judas tree) using the vacuum chamber technique. K stem decreased at leaf water potentials (? L) lower than -1.0 MPa, while K leaf started to decrease only at ? L L K leaf

  7. Why do leaf-tying caterpillars abandon their leaf ties?

    PubMed Central

    Sliwinski, Michelle

    2013-01-01

    Leaf-tying caterpillars act as ecosystem engineers by building shelters between overlapping leaves, which are inhabited by other arthropods. Leaf-tiers have been observed to leave their ties and create new shelters (and thus additional microhabitats), but the ecological factors affecting shelter fidelity are poorly known. For this study, we explored the effects of resource limitation and occupant density on shelter fidelity and assessed the consequences of shelter abandonment. We first quantified the area of leaf material required for a caterpillar to fully develop for two of the most common leaf-tiers that feed on white oak, Quercus alba. On average, Psilocorsis spp. caterpillars consumed 21.65 ± 0.67 cm2 leaf material to complete development. We also measured the area of natural leaf ties found in a Maryland forest, to determine the distribution of resources available to caterpillars in situ. Of 158 natural leaf ties examined, 47% were too small to sustain an average Psilocorsis spp. caterpillar for the entirety of its development. We also manipulated caterpillar densities within experimental ties on potted trees to determine the effects of cohabitants on the likelihood of a caterpillar to leave its tie. We placed 1, 2, or 4 caterpillars in ties of a standard size and monitored the caterpillars twice daily to track their movement. In ties with more than one occupant, caterpillars showed a significantly greater propensity to leave their tie, and left sooner and at a faster rate than those in ties as single occupants. To understand the consequences of leaf tie abandonment, we observed caterpillars searching a tree for a site to build a shelter in the field. This is a risky behavior, as 17% of the caterpillars observed died while searching for a shelter site. Caterpillars that successfully built a shelter traveled 110 ± 20 cm and took 28 ± 7 min to find a suitable site to build a shelter. In conclusion, leaf-tying caterpillars must frequently abandon their leaf tie due to food limitation and interactions with other caterpillars, but this is a costly behavior. PMID:24109557

  8. What determines a leaf's shape?

    PubMed

    Dkhar, Jeremy; Pareek, Ashwani

    2014-01-01

    The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Significant contributions have come from megaphyllous leaves, characterized usually as flat, thin lamina entrenched with photosynthetic organelles and stomata, which serve as the basis of primary productivity. During the course of evolution, the megaphylls have attained complexity not only in size or venation patterns but also in shape. This has fascinated scientists worldwide, and research has progressed tremendously in understanding the concept of leaf shape determination. Here, we review these studies and discuss the various factors that contributed towards shaping the leaf; initiated as a small bulge on the periphery of the shoot apical meristem (SAM) followed by asymmetric outgrowth, expansion and maturation until final shape is achieved. We found that the underlying factors governing these processes are inherently genetic: PIN1 and KNOX1 are indicators of leaf initiation, HD-ZIPIII, KANADI, and YABBY specify leaf outgrowth while ANGUSTIFOLIA3 and GROWTH-REGULATING FACTOR5 control leaf expansion and maturation; besides, recent research has identified new players such as APUM23, known to specify leaf polarity. In addition to genetic control, environmental factors also play an important role during the final adjustment of leaf shape. This immense amount of information available will serve as the basis for studying and understanding innovative leaf morphologies viz. the pitchers of the carnivorous plant Nepenthes which have evolved to provide additional support to the plant survival in its nutrient-deficient habitat. In hindsight, formation of the pitcher tube in Nepenthes might involve the recruitment of similar genetic mechanisms that occur during sympetaly in Petunia. PMID:25584185

  9. Spinach nitrite reductase. Purification and properties of a siroheme-containing iron-sulfur enzyme.

    PubMed

    Vega, J M; Kamin, H

    1977-02-10

    Ferredoxin-nitrite reductase (EC 1.7.7.1.) from spinach has been purified to homogeneity with a specific activity of 110 units/mg of protein. The enzyme, Mr = 61,000 has 3 iron atoms (of which one is in siroheme) and 2 labile sulfides, i.e. 1 (Fe2-S2) per molecule, with absorption maxima at 276, 386 (Soret), 573 (alpha), and 690 nm, with an E386 of 3.97 X 10(4) M-1-cm-1, and A276/A386 absorptivity ratio of 1.8. Anaerobic addition of dithionite results in the loss of the 690 nm peak and the splitting of the 573 nm absorption band into two broad peaks at 545 and 585 nm. Reduction by dithionite is enhanced by cyanide (Fig. 7) and requires about 3 electron eq per mol of enzyme. With nitrite or hydroxylamine (substrates of the enzyme), cyanide (a competitive inhibitor with respect to nitrite), or sulfite, the 690 nm absorption band of substrate-free enzyme disappears and the absorbance in the Soret and alpha region are altered. The high spin EPR signals disappear (J. M. Vega, H. Kamin, N. R. Orme-Johnson, and W. H. Orme-Johnson, unpublished observations). Titration permits calculation of 1 mol of nitrite bound/mol of enzyme with a Kdiss of 3.2 X 10(-6) M. Dithionite-reduced enzyme also forms complexes with added nitrite, hydroxylamine, or cyanide, characterized by marked alterations in the 573 (alpha) absorption band. THus, substrates or competitive inhibitors can be bound to the oxidized or reduced enzyme forms. CO inhibits nitrite reductase and forms a complex with reduced enzyme (epsilonmax at 395, 543, and 585 nm). Formation or dissociation of the spectrophotometrically detectable CO complex correlates with inhibition or inhibition-reversal of nitrite reduction catalysis. During steady state turnover with dithionite and nitrite, the enzyme forms a complex with added nitrite with absorption difference maxima at 445, 538, and 580 nm with respect to reduced enzyme. When nearly all substrate is depleted the spectrum of a new species appears, indicating that nitrite reductase may form complexes with nitrogen compounds of more than one oxidation state. Nitrite is stoichiometrically reduced to ammonia without detectable free nitrogen compounds of intermediate reduction state. p-Chloromercuribenzoate (pCMB) inhibits nitrite reductase activity and nitrite partially protects against this inhibition. Titration of native enzyme with the mercurial shows that 6 mol of pCMB can be bound/mol or nitrite reductase. The Soret absorption band of the native nitrite reductase is altered and partially bleached in the pCMB-treated enzyme, and the 573 (alpha) band disappears. PMID:838704

  10. Identification of the Key Astringent Compounds in Spinach ( Spinacia oleracea ) by Means of the Taste Dilution Analysis

    Microsoft Academic Search

    Annika Brock; Thomas Hofmann

    2008-01-01

    Application of sequential solvent extraction and reverse phase high-performance liquid chromatography separation in combination\\u000a with the taste dilution analysis, followed by liquid chromatography–mass spectroscopy and 1D\\/2D nuclear magnetic resonance\\u000a experiments revealed 11 flavon-3-ol-O-glycosides as the key astringent and mouth-drying compounds in blanched leaves of spinach (Spinacia oleracea). Among these, in particular, 3?,5-dihydroxy-3-methoxy-6:7-methylendioxy-flavon-4?-O-?-d-glucuronide (3), 5-hydroxy-3,3?-dimethoxy-6:7-methylendioxy-flavon-4?-O-?-d-glucuronide (11), and patuletin-3-O-?-d-glucopyranosyl(1?6)-?-d-glucopyranoside (5) were found

  11. NON-DESTRUCTIVE ASSESSMENT OF ARUNDO DONAX (POACEAE) LEAF QUALITY.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf quality information (i.e., leaf C content, leaf N content, leaf C:N ratio) is especially useful for understanding plant-herbivore interactions and may be important in developing control methods for the invasive riparian plant Arundo donax L. We measured leaf C content, leaf N content, leaf C:N ...

  12. Extended-Spectrum Beta-Lactamase Gene Sequences in Gram-Negative Saprophytes on Retail Organic and Nonorganic Spinach ?

    PubMed Central

    Raphael, Eva; Wong, Lisa K.; Riley, Lee W.

    2011-01-01

    A substantial proportion of infections caused by drug-resistant Gram-negative bacteria (GNB) in community and health care settings are recognized to be caused by evolutionarily related GNB strains. Their global spread has been suggested to occur due to human activities, such as food trade and travel. These multidrug-resistant GNB pathogens often harbor mobile drug resistance genes that are highly conserved in their sequences. Because they appear across different GNB species, these genes may have origins other than human pathogens. We hypothesized that saprophytes in common human food products may serve as a reservoir for such genes. Between July 2007 and April 2008, we examined 25 batches of prepackaged retail spinach for cultivatable GNB population structure by 16S rRNA gene sequencing and for antimicrobial drug susceptibility testing and the presence of extended-spectrum beta-lactamase (ESBL) genes. We found 20 recognized GNB species among 165 (71%) of 231 randomly selected colonies cultured from spinach. Twelve strains suspected to express ESBLs based on resistance to cefotaxime and ceftazidime were further examined for blaCTX-M and blaTEM genes. We found a 712-bp sequence in Pseudomonas teessidea that was 100% identical to positions 10 to 722 of an 876-bp blaCTX-M-15 gene of an E. coli strain. Additionally, we identified newly recognized ESBL blaRAHN-2 sequences from Rahnella aquatilis. These observations demonstrate that saprophytes in common fresh produce can harbor drug resistance genes that are also found in internationally circulating strains of GNB pathogens; such a source may thus serve as a reservoir for drug resistance genes that ultimately enter pathogens to affect human health. PMID:21216903

  13. Extended-spectrum Beta-lactamase gene sequences in gram-negative saprophytes on retail organic and nonorganic spinach.

    PubMed

    Raphael, Eva; Wong, Lisa K; Riley, Lee W

    2011-03-01

    A substantial proportion of infections caused by drug-resistant Gram-negative bacteria (GNB) in community and health care settings are recognized to be caused by evolutionarily related GNB strains. Their global spread has been suggested to occur due to human activities, such as food trade and travel. These multidrug-resistant GNB pathogens often harbor mobile drug resistance genes that are highly conserved in their sequences. Because they appear across different GNB species, these genes may have origins other than human pathogens. We hypothesized that saprophytes in common human food products may serve as a reservoir for such genes. Between July 2007 and April 2008, we examined 25 batches of prepackaged retail spinach for cultivatable GNB population structure by 16S rRNA gene sequencing and for antimicrobial drug susceptibility testing and the presence of extended-spectrum beta-lactamase (ESBL) genes. We found 20 recognized GNB species among 165 (71%) of 231 randomly selected colonies cultured from spinach. Twelve strains suspected to express ESBLs based on resistance to cefotaxime and ceftazidime were further examined for bla(CTX-M) and bla(TEM) genes. We found a 712-bp sequence in Pseudomonas teessidea that was 100% identical to positions 10 to 722 of an 876-bp bla(CTX-M-15) gene of an E. coli strain. Additionally, we identified newly recognized ESBL bla(RAHN-2) sequences from Rahnella aquatilis. These observations demonstrate that saprophytes in common fresh produce can harbor drug resistance genes that are also found in internationally circulating strains of GNB pathogens; such a source may thus serve as a reservoir for drug resistance genes that ultimately enter pathogens to affect human health. PMID:21216903

  14. Life in the Leaf Litter

    NSDL National Science Digital Library

    Produced by the Center for Biodiversity and Conservation, Life in the Leaf Litter is a guide to the diversity of soil organisms and the crucial role that invertebrates play in woodland ecosystems. The booklet was based, in part, on a leaf litter survey conducted by the CBC's Metro Program and the Museum's Division of Invertebrate Zoology in Central Park's woodlands, which led to the discovery of a new genus and species of centipede, Nannarrup hoffmani. The booklet may be downloaded as a pdf or ordered free of charge.

  15. 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 (?T), the latter to the transpiration rate. We present field measurements of ?T 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 (?) 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 ?T) 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 and air temperature is generally neglected in terrestrial ecosystem and carbon cycle models. This is a significant omission that could lead to an over-estimation of the heat-stress vulnerability of carbon uptake in the wet tropics. Leaf energy balance theory is well established, and should be included in the next generation of models.

  16. Reduction of Escherichia coli O157:H7 in Fresh Spinach, using lactic acid bacteria and chlorine as a multihurdle intervention.

    PubMed

    Gragg, S E; Brashears, M M

    2010-02-01

    A 12-day shelf life study was conducted at 7 degrees C to determine whether Escherichia coli O157:H7 on spinach can be controlled effectively by selected strains of lactic acid bacteria (LAB) alone or in combination with chlorine as a multihurdle intervention. The multihurdle intervention consisted of both LAB and chlorine and was applied to spinach as a rinse and evaluated in comparison to LAB alone and chlorine and water rinses. Reductions achieved by all treatments also were compared with those observed for an inoculated control. The spinach was inoculated by submersion in a solution containing an E. coli O157:H7 cocktail at 1.0 x 10(6) CFU/ml. LAB were applied postharvest at a concentration of 2.0 x 10(8) CFU/ml, and 200 ppm of chlorine was used for the chlorine rinse. All spinach samples were packaged in commercial packaging, held in a retail display case, and tested for E. coli O157:H7 on days 0, 1, 3, 6, 9, and 12 using the Neo-Grid filtration system and CHROMagar. Survival of LAB throughout the shelf life also was determined. Significant reductions in pathogen populations were achieved by water (P = 0.0008), LAB (P < 0.0001), chlorine (P < 0.0001), and multihurdle (P < 0.0001) treatments when compared with controls. The multihurdle treatment produced the greatest reduction from control populations, a reduction of 1.91 log CFU/ml. This reduction was significantly greater than that achieved with water (P < 0.0001), LAB (P = 0.0025), and chlorine (P < 0.0001) alone, indicating that the application of chlorine and LAB is most effective as a combination treatment. The results obtained from this study indicate that the industry standard chlorine wash may be more effective when applied in combination with LAB. PMID:20132683

  17. Efficacy of washing with hydrogen peroxide followed by aerosolized antimicrobials as a novel sanitizing process to inactivate Escherichia coli O157:H7 on baby spinach.

    PubMed

    Huang, Yaoxin; Ye, Mu; Chen, Haiqiang

    2012-02-15

    Aerosolization was investigated as a potential way to apply allyl isothiocyanate (AIT), hydrogen peroxide (H(2)O(2)), acetic acid (AA) and lactic acid (LA) on fresh baby spinach to control Escherichia coli O157:H7 during refrigeration storage. In this study, baby spinach leaves were dip-inoculated with E. coli O157:H7 to a level of 6 log CFU/g and stored at 4°C for 24 h before treatment. Antimicrobials were atomized into fog-like micro-particles by an ultrasonic nebulizer and routed into a jar and a scale-up model system where samples were treated. Samples were stored at 4°C for up to 10 days before the survival of the cells was determined. A 2-min treatment with 5% AIT resulted in a >5-log reduction of E. coli O157:H7 on spinach after 2 days refrigeration regardless if the samples were pre-washed or not; however, this treatment impaired the sensory quality of leaves. Addition of LA to AIT improved the antimicrobial efficacy of AIT. In the jar system, washing with 3% H(2)O(2) followed by a 2-min treatment of 2.5% LA+1% AIT or 2.5% LA+2% AIT reduced E. coli O157:H7 population by 4.7 and >5 log CFU/g, respectively, after 10 days refrigeration. In the scale-up system, up to 4-log reduction of bacterial population was achieved for the same treatments without causing noticeable adverse effect on the appearance of leaves. Thus, this study demonstrates the potential of aerosolized AIT+LA as a new post-washing intervention strategy to control E. coli O157:H7 on baby spinach during refrigeration storage. PMID:22177228

  18. Cloning, Mapping, and in vitro Transcription--Translation of the Gene for the Large Subunit of Ribulose1,5-bisphosphate Carboxylase from Spinach Chloroplasts

    Microsoft Academic Search

    Jack L. Erion; Joseph Tarnowski; Herbert Weissbach; Nathan Brot

    1981-01-01

    An 11.2-kilobase pair (kbp) BamHI restriction nuclease fragment from spinach chloroplast DNA has been found to contain the gene for the large subunit (LS) of ribulose-1,5-bisphosphate carboxylase [RuP2 carboxylase; 3-phospho-D-glycerate carboxy-lyase (dimerizing), EC 4.1.1.39]. The gene was located by hybridization of cloned chloroplast DNA fragments containing the maize LS gene (Bedbrook, J. R., Coen, D. M., Beaton, A. R., Bogorad,

  19. Intergeneric recombination between a new, spinach-infecting curtovirus and a new geminivirus belonging to the genus Becurtovirus: first New World exemplar.

    PubMed

    Hernández-Zepeda, Cecilia; Varsani, Arvind; Brown, Judith K

    2013-11-01

    A novel curtovirus, spinach severe curly top virus (SSCTV), was associated with symptomatic spinach plants collected from a commercial field in south-central Arizona during 2009. In addition, a second viral molecule of about 2.9 kb from the same spinach plants was amplified, cloned and sequenced. The latter isolate, herein named spinach curly top Arizona virus (SCTAV), was found to share 77 % pairwise sequence identity with beet curly top Iran virus (BCTIV), a leafhopper-transmitted geminivirus that has been assigned to the new genus Becurtovirus. The SCTAV genome encodes three viral-sense genes, V1, V2, and V3, and two complementary-sense genes, C1 and C2. There was no evidence for the presence of either a C3 or C4 ORF in the genome sequence. The genome organization of SCTAV is not like that of New World curtoviruses but instead is similar to that of BCTIV, which, to date, is only known to be present in Iran. Consistent with this observation, SCTAV and BCTIV both contain the unusual nonanucleotide TAAGATT/CC and a replication-associated protein, Rep (or C1), that is more closely related to the mastrevirus Rep than to those of curtoviruses reported to date. Both SSCTV and SCTAV were found to have a recombinant genome containing sequences (AY548948) derived from ancestral SCTV sequences in the virion-sense portions of the genome. Agroinoculation of Nicotiana benthamiana (Domin) plants with the cloned genome of SCTAV resulted in infection of 95 % of the plants and the development of severe curling symptoms, whereas only 20 % of the SSCTV-inoculated plants were infected, developing only mild curling symptoms. When plants were co-inoculated with both viruses, the frequency of infection remained higher for SCTAV than for SSCTV (80 % vs. 20 %), indicating no evidence of synergistic effects between the two viruses with respect to efficiency of infection. PMID:23708296

  20. The influence of metal cations and pH on the heat sensitivity of photosynthetic oxygen evolution and chlorophyll fluorescence in spinach chloroplasts

    Microsoft Academic Search

    Engelbert Weis

    1982-01-01

    The heat-sensitivity of photosynthetic oxygen evolution of thylakoids isolated from spinach increases by increasing the pH above neutral value. The temperature for inactivation (transition temperature) is lowered from about 45° C (pH 6.0–7.4) to 33°C (pH 8.5). Similar results are obtained with intact chloroplasts. At pH 7.0 the transition temperature of washed thylakoids decreases by lowering the salt concentration below

  1. Glutathione reductase: Comparison of steady-state and rapid reaction primary kinetic isotope effects exhibited by the yeast, spinach, and Escherichia coli enzymes

    SciTech Connect

    Vanoni, M.A.; Wong, K.K.; Ballou, D.P.; Blanchard, J.S. (Albert Einstein College of Medicine, Bronx, NY (USA))

    1990-06-19

    Kinetic parameters for NADPH and NADH have been determined at pH 8.1 for spinach, yeast, and E. coli glutathione reductases. NADPH exhibited low Km values for all enzymes (3-6 microM), while the Km values for NADH were 100 times higher (approximately 400 microM). Under our experimental conditions, the percentage of maximal velocities with NADH versus those measured with NADPH were 18.4, 3.7, and 0.13% for the spinach, yeast, and E. coli enzymes, respectively. Primary deuterium kinetic isotope effects were independent of GSSG concentration between Km and 15Km levels, supporting a ping-pong kinetic mechanism. For each of the three enzymes, NADPH yielded primary deuterium kinetic isotope effects on Vmax only, while NADH exhibited primary deuterium kinetic isotope effects on both V and V/K. The magnitude of DV/KNADH at pH 8.1 is 4.3 for the spinach enzyme, 2.7 for the yeast enzyme, and 1.6 for the E. coli glutathione reductase. The experimentally determined values of TV/KNADH of 7.4, 4.2, and 2.2 for the spinach, yeast, and E. coli glutathione reductases agree well with those calculated from the corresponding DV/KNADH using the Swain-Schaad expression. This suggests that the intrinsic primary kinetic isotope effect on NADH oxidation is fully expressed. In order to confirm this conclusion, single-turnover experiments have been performed. The measured primary deuterium kinetic isotope effects on the enzyme reduction half-reaction using NADH match those measured in the steady state for each of the three glutathione reductases.

  2. Effect of repeated irrigation with water containing varying levels of total organic carbon on the persistence of Escherichia coli O157:H7 on baby spinach.

    PubMed

    Ingram, David T; Patel, Jitu; Sharma, Manan

    2011-05-01

    The California lettuce and leafy greens industry has adopted the Leafy Greens Marketing Agreement (LGMA), which allows for 126 most-probable-number (MPN) Escherichia coli per 100 ml in irrigation water. Repeat irrigation of baby spinach plants with water containing E. coli O157:H7 and different levels of total organic carbon (TOC) was used to determine the epiphytic survival of E. coli O157:H7. Three irrigation treatments (0 ppm of TOC, 12 or 15 ppm of TOC, and 120 or 150 ppm of TOC) were prepared with bovine manure containing E. coli O157:H7 at either low (0 to 1 log CFU/100 ml) or high (5 to 6 log CFU/100 ml) populations, and sprayed onto baby spinach plants in growth chambers by using a fine-mist airbrush. MPN and direct plating techniques were used to determine the E. coli O157:H7 populations on the aerial plant tissue. Plants irrigated with high E. coli O157:H7 populations, regardless of TOC levels, showed a 3-log reduction within the first 24 h. Low levels of E. coli O157:H7 were observed for up to 16 days on all TOC treatments, ranging from 76.4 MPN per plant (day 1) to 0.40 MPN per plant (day 16). No viable cells were detected on spinach tissue 24 h after irrigation with water containing fewer than 126 CFU/100 ml E. coli O157:H7. Under growth chamber conditions in this study, E. coli O157:H7 populations in irrigation water that complies with the LGMA standards will not persist for more than 24 h when applied onto foliar surfaces of spinach plants. PMID:21549040

  3. Isolation of Mesophyll Cells and Bundle Sheath Cells from Digitaria sanguinalis (L.) Scop. Leaves and a Scanning Microscopy Study of the Internal Leaf Cell Morphology 1

    PubMed Central

    Edwards, Gerald E.; Black, Clanton C.

    1971-01-01

    A technique is described for the separation of mesophyll and bundle sheath cells from Digitaria sanguinalis leaves and evidence for separation is given with light and scanning electron micrographs. Gentle grinding of fully differentiated leaves in a mortar releases mesophyll cells which are isolated on nylon nets by filtration. More extensive grinding of the remaining tissue yields bundle sheath strands which are isolated by filtration with stainless steel sieves and nylon nets. Further grinding of bundle sheath strands in a tissue homogenizer releases bundle sheath cells which are collected on nylon nets. Percentage of purity derived from cell counts and yield data on a chlorophyll basis are given. The internal leaf cell morphology is presented in scanning electron micrographs and compared with light micrographs of fully-differentiated D. sanguinalis leaves. In leaves of plants which possess the C4-dicarboxylic acid cycle of photosynthesis, the relationship of leaf morphology to photosynthesis in mesophyll and bundle sheath cells is considered, and the hypothesis is presented that as atmospheric CO2 enters a leaf about 85% is fixed by the C4-dicarboxylic acid cycle in the mesophyll cells and 10 to 15% is fixed by the reductive pentose phosphate cycle in the bundle sheath cells. A technique also is given for the isolation of mesophyll cells from spinach leaves. Images PMID:16657571

  4. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471...TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is...

  5. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471...TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is...

  6. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471...TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is...

  7. An Innovative Way to Monitor Leaf Age

    NASA Astrophysics Data System (ADS)

    Garnello, A.; Paredes, K.; Trinh, U.; Saleska, S. R.; Wu, J.

    2013-12-01

    Anthony John Garnello, Karina Paredes, Uyen Khanh Ho Trinh, Jin Wu, Scott Saleska Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA Abstract: Leaf age is an important characteristic for controlling plant functional performance and is associated with the changes of leaf physical, chemical, and physiological properties. Understanding how plant physiology changes over time will allow more accurate predictions of growth patterns, and a more comprehensive understanding of vegetative life histories. There still lacks an efficient technique in monitoring leaf age, tagging leaves is still the only way to accurately monitor leaf age. The goal of this study is to develop a multi-metric, accurate technique for better monitoring of leaf age. In order to acquire true leaf age records, 10 individual plant species were selected at the University of Arizona campus, and newly flushing leaves were tagged and monitored during the Monsoon season (from early June, 2013, to mid October, 2013). Every 2 weeks, 10 to 15 leaves in relative age order were harvested from each 1-meter branch to measure multiple key leaf metrics, including leaf thickness (via micrometer), fresh and dry weight, fresh and dry area (via ImageJ software), and leaf hyperspectral reflectance (via a handheld ASD Field Pro). Other leaf traits were also derived from our measurements, such as specific leaf area (SLA), leaf density (fresh weight/leaf volume), water percentage, and shrinkage ratio (1-dry area/fresh area). The hyperspectral version of vegetation index (a ratio derived from two spectral channels) was generated for each branch sample, by randomly selecting two channels from within the spectral domain of 350 nm to 2500 nm. The preliminary result documents three types of hyperspectral vegetation index (VI) which are highly related with leaf relative age order (R2>0.9). These include the sensitive spectral domains correlated with (a) leaf pigments (~550nm) and leaf physical structure (750nm-1000nm), (b) leaf pigments (~550nm) and leaf water concentration (1400nm-2300nm), and (c) leaf physical structure (750nm-1000nm) and leaf water concentration (1400nm-2300nm). Preliminary results showed that (1) among the key leaf traits, leaf shrinkage is the only trait that showed a consistent correlation with relative age order across the samples; (2) a power function best modeled the interspecies relationship between leaf shrinkage and leaf age (R2 = 0.81, p-value < 0.01, 22 data points for 7 species); (3) a strong correlation was found between the predicted leaf age using the species specific power functions of leaf shrinkage and true leaf age (R2= 0.96, p-value < 0.01), suggesting that leaf shrinkage could be a useful trait for prediction of absolute leaf age in the future. In the next step, we will integrate leaf shrinkage based leaf age prediction with hyperspectral VI framework, aiming to derive some reliable VIs which can be universal for leaf aging prediction among all the species.

  8. The scaling of leaf area and mass: the cost of light interception increases with leaf size

    E-print Network

    Minnesota, University of

    The scaling of leaf area and mass: the cost of light interception increases with leaf size Rube (specific leaf area, SLA) is a key trait from physiological, ecological and biophysical perspectives. To address whether SLA declines with leaf size, as hypothesized due to increasing costs of support in larger

  9. Leaf number, water stress and carbon nutrition effects on poplar leaf growth

    E-print Network

    Paris-Sud XI, Université de

    Leaf number, water stress and carbon nutrition effects on poplar leaf growth J.P. Gaudillère area of a leaf is described by the number and the mean size of epidermal cells. Water stress, nitrogen at different levels in the process of leaf production. The main susceptible physio- logical mechanisms are cell

  10. 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...

  11. Original article Photosynthesis, leaf area and productivity

    E-print Network

    Paris-Sud XI, Université de

    Original article Photosynthesis, leaf area and productivity of 5 poplar clones during; The stem volume and biomass (stem + branches) production, net photosynthesis of mature leaves and leaf area found in volume production, woody biomass production, total leaf area and net photosynthesis. Above

  12. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture...Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  13. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2 2012-01-01 2012-01-01 false Leaf structure. 29.2278 Section 29.2278...Fire-Cured Tobacco (u.s. Type 21) § 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

  14. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture...36, 37 and Foreign Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

  15. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2 2013-01-01 2013-01-01 false Leaf structure. 29.2278 Section 29.2278...Fire-Cured Tobacco (u.s. Type 21) § 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

  16. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture...Type 31 and Foreign Type 93) § 29.3034 Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  17. Leaf Sequencing Algorithms for Segmented Multileaf Collimation

    E-print Network

    Sahni, Sartaj K.

    Leaf Sequencing Algorithms for Segmented Multileaf Collimation Srijit Kamath, Sartaj Sahni fluence map into a leaf sequence file that controls the movement of the MLC during radiation delivery. It is imperative that the fluence map delivered using the leaf sequence file is as close as possible to the fluence

  18. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2 2014-01-01 2014-01-01 false Leaf structure. 29.2278 Section 29.2278...Fire-Cured Tobacco (u.s. Type 21) § 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

  19. Parameterized Algorithms for Directed Maximum Leaf Problems

    E-print Network

    Krivelevich, Michael

    Parameterized Algorithms for Directed Maximum Leaf Problems Noga Alon 1 , Fedor V. Fomin 2 spanning tree, then D contains one with at least (n/2) 1/5 - 1 leaves. 1 Introduction The Maximum Leaf a digraph D, the Directed Maximum Leaf Out­Branching problem is the problem of finding an out­branching in D

  20. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture...Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  1. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture...Type 31 and Foreign Type 93) § 29.3034 Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  2. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture...Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  3. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture...36, 37 and Foreign Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

  4. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture...Type 31 and Foreign Type 93) § 29.3034 Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed...

  5. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture...36, 37 and Foreign Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

  6. 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 ...

  7. XANTHOMONAS LEAF BLIGHT OF ONION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xanthomonas leaf blight, caused by the bacterium Xanthomonas axonopodis pv. allii, is a common foliar disease of onion. This extension bulletin presents a review of disease symptomology, etiology, epidemiology, and management. The association of environment, host, and cultural and disease severity ...

  8. Leaf Photosynthesis Under Drought Stress

    Microsoft Academic Search

    Gabriel Cornic; Angelo Massacci

    The photosynthetic apparatus is resistant to drought. Net CO2 uptake of a leaf submitted to a mild desiccation decreases because of stomatal closure. As aresult, CO2 concentration in the chloroplast decreases in plants exposed to water shortage. This drop in the chloroplast CO2 concentration causes: (i) a decrease in photochemical yield of open PS II centers and, consequently, an increase

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

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...percent may be waste. B4G—Fair Quality Green Leaf Immature, close leaf structure...percent may be waste. B5G—Low Quality Green Leaf Immature, tight leaf structure...percent may be waste. B6G—Poor Quality Green Leaf Immature, tight leaf...

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

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...percent may be waste. B4G—Fair Quality Green Leaf Immature, close leaf structure...percent may be waste. B5G—Low Quality Green Leaf Immature, tight leaf structure...percent may be waste. B6G—Poor Quality Green Leaf Immature, tight leaf...

  11. Leaf area dynamics of conifer forests

    SciTech Connect

    Margolis, H.; Oren, R.; Whitehead, D.; Kaufmann, M.R.

    1995-07-01

    Estimating the surface area of foliage supported by a coniferous forest canopy is critical for modeling its biological properties. Leaf area represents the surface area available for the interception of energy, the absorption of carbon dioxide, and the diffusion of water from the leaf to the atmosphere. The concept of leaf area is pertinent to the physiological and ecological dynamics of conifers at a wide range of spatial scales, from individual leaves to entire biomes. In fact, the leaf area of vegetation at a global level can be thought of as a carbon-absorbing, water-emitting membrane of variable thickness, which can have an important influence on the dynamics and chemistry of the Earth`s atmosphere over both the short and the long term. Unless otherwise specified, references to leaf area herein refer to projected leaf area, i.e., the vertical projection of needles placed on a flat plane. Total leaf surface area is generally from 2.0 to 3.14 times that of projected leaf area for conifers. It has recently been suggested that hemisurface leaf area, i.e., one-half of the total surface area of a leaf, a more useful basis for expressing leaf area than is projected area. This chapter is concerned with the dynamics of coniferous forest leaf area at different spatial and temporal scales. In the first part, we consider various hypotheses related to the control of leaf area development, ranging from simple allometric relations with tree size to more complex mechanistic models that consider the movement of water and nutrients to tree canopies. In the second part, we consider various aspects of leaf area dynamics at varying spatial and temporal scales, including responses to perturbation, seasonal dynamics, genetic variation in crown architecture, the responses to silvicultural treatments, the causes and consequences of senescence, and the direct measurement of coniferous leaf area at large spatial scales using remote sensing.

  12. Effects of carbon dioxide and oxygen on the regulation of photosynthetic carbon metabolism by ammonia in spinach mesophyll cells

    SciTech Connect

    Lawyer, A.L.; Cornwell, K.L.; Larsen, P.O.; Bassham, J.A.

    1981-01-01

    Photosynthetic carbon metabolism of isolated spinach mesophyll cells was characterized under conditions favoring photorespiratory (PR; 0.04% CO/sub 2/ and 20% O/sub 2/) and nonphotorespiratory (NPR; 0.2% CO/sub 2/ and 2% O/sub 2/) metabolism, as well as intermediate conditions. Comparisons were made between the metabolic effects of extracellularly supplied NH/sub 4//sup +/ and intracellular NH/sub 4//sup +/, produced primarily via PR metabolism. The metabolic effects of /sup 14/CO/sub 2/ fixation under PR conditions were similar to perturbations of photosynthetic metabolism brought about by externally supplied NH/sub 4//sup +/; both increased labeling and intracellular concentrations of glutamine at the expense of glutamate and increased anaplerotic synthesis through ..cap alpha..-ketoglutarate. The metabolic effects of added NH/sub 4//sup +/ during NPR fixation were greater than those during PR fixation, presumably due to lower initial NH/sub 4//sup +/ levels during NPR fixation. During PR fixation, addition of ammonia caused decreased pools and labeling of glutamate and serine and increased glycolate, glyoxylate, and glycine labeling. The glycolate pathway was thus affected by increased rates of carbon flow and decreased glutamate availability for glyoxylate transamination, resulting in increased usage of serine for transamination. Sucrose labeling decreased with NH/sub 4//sup +/ addition only during PR fixation, suggesting that higher photosynthetic rates under NPR conditions can accommodate the increased drain of carbon toward amino acid synthesis while maintaining sucrose synthesis.

  13. Reduction of Nitrate via a Dicarboxylate Shuttle in a Reconstituted System of Supernatant and Mitochondria from Spinach Leaves 1

    PubMed Central

    Woo, K. C.; Jokinen, Mark; Canvin, David T.

    1980-01-01

    Substantial rates of nitrate reduction could be achieved with a reconstituted system from spinach leaves containing supernatant, mitochondria, NAD+, oxaloacetate (OAA), and an oxidizable substrate. Appropriate substrates were glycine, pyruvate, citrate, isocitrate, fumarate, or glutamate. The reduction of NO3? with any of the substrates could be inhibited by n-butyl malonate, showing that the transfer of reducing power from the mitochondria to the supernatant involved the malate exchange carrier. The addition of ADP to the reconstituted system decreased NO3? reduction and this decrease could be reversed by the addition of rotenone or antimycin A. The operation of the OAA/malate shuttle was achieved most quickly in the system when low concentrations (?0.1 millimolar) of OAA were added. A corresponding increase in the lag time for the operation of the OAA/malate shuttle was observed when the OAA concentration was increased. Concentrations for half-maximal activity of OAA, glycine, NAD+, and NO3? in the reconstituted system were 42 micromolar, 0.5 millimolar, 0.25 millimolar, and 26 micromolar, respectively. The transfer of reducing power from the mitochondria to the soluble phase via the OAA/malate shuttle can not only provide NADH for cytoplasmic reduction but can also sustain oxidation of tricarboxylic cycle acids and the generation of ?-ketoglutarate independently of the respiratory electron transport chain. PMID:16661207

  14. Nanodomains of Cytochrome b6f and Photosystem II Complexes in Spinach Grana Thylakoid Membranes[W][OPEN

    PubMed Central

    Johnson, Matthew P.; Vasilev, Cvetelin; Olsen, John D.; Hunter, C. Neil

    2014-01-01

    The cytochrome b6f (cytb6f) complex plays a central role in photosynthesis, coupling electron transport between photosystem II (PSII) and photosystem I to the generation of a transmembrane proton gradient used for the biosynthesis of ATP. Photosynthesis relies on rapid shuttling of electrons by plastoquinone (PQ) molecules between PSII and cytb6f complexes in the lipid phase of the thylakoid membrane. Thus, the relative membrane location of these complexes is crucial, yet remains unknown. Here, we exploit the selective binding of the electron transfer protein plastocyanin (Pc) to the lumenal membrane surface of the cytb6f complex using a Pc-functionalized atomic force microscope (AFM) probe to identify the position of cytb6f complexes in grana thylakoid membranes from spinach (Spinacia oleracea). This affinity-mapping AFM method directly correlates membrane surface topography with Pc-cytb6f interactions, allowing us to construct a map of the grana thylakoid membrane that reveals nanodomains of colocalized PSII and cytb6f complexes. We suggest that the close proximity between PSII and cytb6f complexes integrates solar energy conversion and electron transfer by fostering short-range diffusion of PQ in the protein-crowded thylakoid membrane, thereby optimizing photosynthetic efficiency. PMID:25035407

  15. Molecular cloning and characterization of pathogenesis-related protein family 10 gene from spinach (SoPR10).

    PubMed

    Bai, Xuegui; Long, Juan; He, Xiaozhao; Li, Shun; Xu, Huini

    2014-01-01

    PR10 genes encode small, intracellular proteins that respond to biotic and abiotic stresses. In this study, a cDNA clone (designated as SoPR10, GenBank Accession No. KC142174) encoding a PR10 protein from spinach (Spinacia oleracea L.) was isolated and characterized. SoPR10 encoded a 161-amino acid polypeptide with a predicted molecular mass of 19.76 kDa and a pI of 4.61. Real-time quantitative analysis indicated that SoPR10 was constitutively expressed in root and shoot. The abundance of SoPR10 in salt-resistant cultivar (Chaoji) was generally greater than in salt-sensitive cultivar (Daye) under 160 mM L(-1) NO3(-) treatment for 0.5, 3, and 6?h. The expression of SoPR10 was also induced by other abiotic stresses including polyethylene glycol, NaCl, salicylic acid, and H2O2. Our results indicated that SoPR10 might play important roles under nitrate stress and other abiotic stresses. PMID:25035979

  16. Derivatives of diterpen labdane-8?,15-diol as photosynthetic inhibitors in spinach chloroplasts and growth plant inhibitors.

    PubMed

    Morales-Flores, Félix; Aguilar, María Isabel; King-Díaz, Beatriz; Lotina-Hennsen, Blas

    2013-08-01

    In a search of new efficient herbicides of natural origin, four derivatives were prepared from labdane-8?,15-diol (1) and 15-O-acetyl-8?-hydroxy labdane (2) isolated from Croton ciliatoglanduliferus. Their inhibitory activity on photosynthetic electron transport on fresh, broken spinach chloroplasts and on the growth of plants were determined. Derivative 15-O-benzoyl-8?-hydroxy labdane (5) was seven times more active than 2 as reaction Hill inhibitor. Complex of 5 with the adjuvant 2-hydroxypropyl-?-cyclodextrin (5:HPB) (200 ?M) was sprayed on Physalys ixocarpa (green tomato) plants; 48 h later the complex inhibited PS II by transforming the active reaction centers to silent reaction centers or "heat sinks". After 72 h this effect disappeared, probably 5:HPB was metabolized by the plant. Chlorophyll a fluorescence of Trifolium alexandrinum (clover) leaves was affected with 5:HPB at the level of PQ pool reduction. 5:HPB decreases the tomato and clover dry-biomass, without affecting Lolium perenne (grass) plants, suggesting that complex 5 acts as selective herbicide for dicotyledonous plants. PMID:23733160

  17. Basella alba rubra spinach pigment-sensitized TiO2 thin film-based solar cells

    NASA Astrophysics Data System (ADS)

    Gokilamani, N.; Muthukumarasamy, N.; Thambidurai, M.; Ranjitha, A.; Velauthapillai, Dhayalan

    2015-03-01

    Nanocrystalline TiO2 thin films have been prepared by sol-gel dip coating method. The X-ray diffraction results showed that TiO2 thin films annealed at 400, 450 and 500 °C are of anatase phase and the peak corresponding to the (101) plane is present in all the samples. The grain size of TiO2 thin films was found to increase with increasing annealing temperature. The grain size is found to be 20, 25 and 33 nm for the films annealed at 400, 450 and 500 °C. The structure of the TiO2 nanocrystalline thin films have been examined by high-resolution transmission electron microscope, Raman spectroscopy and FTIR spectroscopy. TiO2 thin films were sensitized by natural dyes extracted from basella alba rubra spinach. It was found that the absorption peak of basella alba rubra extract is at about 665 nm. The dye-sensitized TiO2-based solar cell sensitized using basella alba rubra exhibited a J sc of 4.35 mA cm-2, V oc of 0.48 V, FF of 0.35 and efficiency of 0.70 %. Natural dyes as sensitizers for dye-sensitized solar cells are promising because of their environmental friendliness, low-cost production and fully biodegradable.

  18. 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

  19. 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

  20. Leaf hydraulic conductance is coordinated with leaf morpho-anatomical traits and nitrogen status in the genus Oryza.

    PubMed

    Xiong, Dongliang; Yu, Tingting; Zhang, Tong; Li, Yong; Peng, Shaobing; Huang, Jianliang

    2015-02-01

    Leaf hydraulic conductance (K leaf) is a major determinant of photosynthetic rate in plants. Previous work has assessed the relationships between leaf morpho-anatomical traits and K leaf with woody species, but there has been very little focus on cereal crops. The genus Oryza, which includes rice (Oryza sativa) and wild species (such as O. rufipogon cv. Griff), is ideal material for identifying leaf features associated with K leaf and gas exchange. Leaf morpho-anatomical traits, K leaf, leaf N content per leaf area, and CO2 diffusion efficiency were investigated in 11 Oryza cultivars. K leaf was positively correlated with leaf thickness and related traits, and therefore positively correlated with leaf mass per area and leaf N content per leaf area, and negatively with inter-veinal distance. K leaf was also positively correlated with leaf area and its related traits, and therefore negatively correlated with the proportion of minor vein length per area. In addition, coordination between K leaf and CO2 diffusion conductance in leaves was observed. We conclude that leaf morpho-anatomical traits and N content per leaf area strongly influence K leaf. Our results suggest that more detailed anatomical and structural studies are needed to elucidate the impacts of leaf feature traits on K leaf and gas exchange in grasses. PMID:25429002

  1. Leaf hydraulic conductance is coordinated with leaf morpho-anatomical traits and nitrogen status in the genus Oryza

    PubMed Central

    Xiong, Dongliang; Yu, Tingting; Zhang, Tong; Li, Yong; Peng, Shaobing; Huang, Jianliang

    2015-01-01

    Leaf hydraulic conductance (K leaf) is a major determinant of photosynthetic rate in plants. Previous work has assessed the relationships between leaf morpho-anatomical traits and K leaf with woody species, but there has been very little focus on cereal crops. The genus Oryza, which includes rice (Oryza sativa) and wild species (such as O. rufipogon cv. Griff), is ideal material for identifying leaf features associated with K leaf and gas exchange. Leaf morpho-anatomical traits, K leaf, leaf N content per leaf area, and CO2 diffusion efficiency were investigated in 11 Oryza cultivars. K leaf was positively correlated with leaf thickness and related traits, and therefore positively correlated with leaf mass per area and leaf N content per leaf area, and negatively with inter-veinal distance. K leaf was also positively correlated with leaf area and its related traits, and therefore negatively correlated with the proportion of minor vein length per area. In addition, coordination between K leaf and CO2 diffusion conductance in leaves was observed. We conclude that leaf morpho-anatomical traits and N content per leaf area strongly influence K leaf. Our results suggest that more detailed anatomical and structural studies are needed to elucidate the impacts of leaf feature traits on K leaf and gas exchange in grasses. PMID:25429002

  2. LeafJ: An ImageJ Plugin for Semi-automated Leaf Shape Measurement

    PubMed Central

    Mumbach, Maxwell R.; Palmer, Christine M.

    2013-01-01

    High throughput phenotyping (phenomics) is a powerful tool for linking genes to their functions (see review1 and recent examples2-4). 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 tools5,6. 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)7. Among SAS responses, shade induced leaf petiole elongation and changes in blade area are particularly useful as indices8. To date, leaf shape programs (e.g. SHAPE9, LAMINA10, LeafAnalyzer11, LEAFPROCESSOR12) 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 size13. 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

  3. Perspectives on leaf dorsoventral polarity

    Microsoft Academic Search

    Dóra Szakonyi; Alexis Moschopoulos; Mary E. Byrne

    2010-01-01

    Leaves occur in a vast array of shapes and sizes, with complex diversity contributing to optimization of the principal function\\u000a of photosynthesis. The program of development from a self-renewing stem cell population to a mature leaf has been of interest\\u000a to biologists for years. Many genes involved in this process have been identified, particularly in the model eudicot Arabidopsis,\\u000a so

  4. Effects of stomatal density and leaf water content on the ¹?O enrichment of leaf water.

    PubMed

    Larcher, Leticia; Hara-Nishimura, Ikuko; Sternberg, Leonel

    2015-04-01

    Leaf water isotopic composition is imprinted in several biomarkers of interest and it is imperative that we understand the isotopic enrichment of leaf water. Here, we test the effect of stomatal density and leaf water content on the oxygen isotopic composition of leaf water in transgenic Arabidopsis plants expressing different stomatal densities, and several other species showing a range of stomatal density. We grew Arabidopsis plants hydroponically and collected other species in the field. Stomatal density and leaf water content were determined for each plant. We measured transpiration and extracted leaf water for isotopic determination. Using these measurements and the current leaf water isotope model, we calculated several of the parameters related to leaf water isotopic enrichment. High stomatal density promoted leaf water isotope enrichment. No conclusion, however, can be drawn regarding the effect of leaf water content on leaf water isotope enrichment. Factors such as transpiration might mask the effect of stomatal density on leaf water isotopic enrichment. We propose a method by which stomatal density can be incorporated in the current Peclet model of leaf water isotope enrichment. These findings have important applications in the use of plant-based metabolic proxies in paleoclimate studies. PMID:25408145

  5. Comparison of Survival of Campylobacter jejuni in the Phyllosphere with That in the Rhizosphere of Spinach and Radish Plants

    Microsoft Academic Search

    Maria T. Brandl; Aileen F. Haxo; Anna H. Bates; Robert E. Mandrell

    2004-01-01

    Campylobacter jejuni has been isolated previously from market produce and has caused gastroenteritis outbreaks linked to produce. We have tested the ability of this human pathogen to utilize organic compounds that are present in leaf and root exudates and to survive in the plant environment under various conditions. Carbon utilization profiles revealed that C. jejuni can utilize many organic acids

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

    E-print Network

    Bermingham, Eldredge

    their symbiont fungus. The ants' fungal symbiont then partially degrades the leaf material, converting leaf; in the latter endophyte composition changed * Correspondence: svanbael@tulane.edu 1 Department of Ecology

  7. Occurrence and genetic diversity of Arcobacter spp. in a spinach-processing plant and evaluation of two Arcobacter-specific quantitative PCR assays.

    PubMed

    Hausdorf, Lena; Neumann, Maria; Bergmann, Ingo; Sobiella, Kerstin; Mundt, Kerstin; Fröhling, Antje; Schlüter, Oliver; Klocke, Michael

    2013-06-01

    Some species of the genus Arcobacter are considered to be emerging food pathogens. With respect to recent vegetable-borne outbreaks, the aim of this work was to investigate the occurrence and diversity of Arcobacter within the production chain of a spinach-processing plant by a combination of cultivation and molecular methods. Samples including spinach, water, and surface biofilm were taken over a period of three years from the entire processing line. Ten 16S rRNA (rrs) gene clone libraries were constructed and analysed using amplified rRNA gene restriction analysis (ARDRA). Approximately 1200 clones were studied that resulted in 44 operational taxonomic units (OTUs). Sequences with high similarities to Arcobacter cryaerophilus (13% of clones, 3 OTUs), A. ellisii (4%, 6 OTUs), A. suis (15%, 3 OTUs), and the type strain of A. nitrofigilis (1%, 7 OTUs) were identified. This represents the first report of the detection of the recently described species A. ellisii, A. suis and, in addition, A. venerupis from alternative habitats. A total of 67% of the clones (22 OTUs) could not be assigned to a genus, which indicated the presence of uncharacterised Arcobacter species. For the cultivation-independent detection of Arcobacter, two genus-specific quantitative PCR (qPCR) assays were developed and tested on 15 Arcobacter species. When these assays were applied to samples from the spinach-processing plant, they showed positive results for up to 35% of the samples and supported the conclusion that there is a considerable risk for the transfer of pathogenic Arcobacter species on vegetables, which was also verified by a cultivation approach. PMID:23561260

  8. Farm Management, Environment, and Weather Factors Jointly Affect the Probability of Spinach Contamination by Generic Escherichia coli at the Preharvest Stage

    PubMed Central

    Navratil, Sarah; Gregory, Ashley; Bauer, Arin; Srinath, Indumathi; Szonyi, Barbara; Nightingale, Kendra; Anciso, Juan; Jun, Mikyoung; Han, Daikwon; Lawhon, Sara; Ivanek, Renata

    2014-01-01

    The National Resources Information (NRI) databases provide underutilized information on the local farm conditions that may predict microbial contamination of leafy greens at preharvest. Our objective was to identify NRI weather and landscape factors affecting spinach contamination with generic Escherichia coli individually and jointly with farm management and environmental factors. For each of the 955 georeferenced spinach samples (including 63 positive samples) collected between 2010 and 2012 on 12 farms in Colorado and Texas, we extracted variables describing the local weather (ambient temperature, precipitation, and wind speed) and landscape (soil characteristics and proximity to roads and water bodies) from NRI databases. Variables describing farm management and environment were obtained from a survey of the enrolled farms. The variables were evaluated using a mixed-effect logistic regression model with random effects for farm and date. The model identified precipitation as a single NRI predictor of spinach contamination with generic E. coli, indicating that the contamination probability increases with an increasing mean amount of rain (mm) in the past 29 days (odds ratio [OR] = 3.5). The model also identified the farm's hygiene practices as a protective factor (OR = 0.06) and manure application (OR = 52.2) and state (OR = 108.1) as risk factors. In cross-validation, the model showed a solid predictive performance, with an area under the receiver operating characteristic (ROC) curve of 81%. Overall, the findings highlighted the utility of NRI precipitation data in predicting contamination and demonstrated that farm management, environment, and weather factors should be considered jointly in development of good agricultural practices and measures to reduce produce contamination. PMID:24509926

  9. An epoxide-furanoid rearrangement of spinach neoxanthin occurs in the gastrointestinal tract of mice and in vitro: formation and cytostatic activity of neochrome stereoisomers.

    PubMed

    Asai, Akira; Terasaki, Masaru; Nagao, Akihiko

    2004-09-01

    Neoxanthin, a major carotenoid in green leafy vegetables, was reported to exhibit potent antiproliferative effect via apoptosis induction on human prostate cancer cells. However, the metabolic fate of dietary neoxanthin in mammals remains unknown. In the present study, we investigated the gastrointestinal metabolism of neoxanthin in mice and the in vitro digestion of spinach, and estimated the antiproliferative effect of neoxanthin metabolites on PC-3 human prostate cancer cells. Two hours after the oral administration to mice of purified neoxanthin, unchanged neoxanthin and stereoisomers of neochrome (8'-R/S) were detected in the plasma, liver, and small intestinal contents. To estimate the effect of intragastric acidity on the conversion of dietary neoxanthin into neochrome (epoxide-furanoid rearrangement), spinach was digested in vitro by incubating it with a pepsin-HCl solution at pH 2.0 or 3.0 (gastric phase) followed by a pancreatin-bile salt solution (intestinal phase). Spinach neoxanthin was largely converted into (R/S)-neochrome during the digestion when the gastric phase was set at pH 2.0, whereas the rearrangement was observed to a lesser extent at pH 3.0. (R/S)-neochrome dose-dependently inhibited the proliferation of PC-3 cells as well as neoxanthin at concentrations < or = 20 micromol/L. Although neoxanthin induced evident apoptotic cell death, (R/S)-neochrome inhibited the cell proliferation without obvious apoptosis induction. These results indicate that dietary neoxanthin is partially converted into (R/S)-neochrome by intragastric acidity before intestinal absorption and that (R/S)-neochrome exhibits an antiproliferative effect on PC-3 cells by the induction of cytostasis. PMID:15333710

  10. GELATION OF ALFALFA SOLUBLE LEAF PROTEINS

    Microsoft Academic Search

    B. P. Lamsal; R. G. Koegel; S. Gunasekaran

    Various alfalfa soluble leaf protein concentrates were prepared by freeze-drying acid-precipitated proteins (pH 3.5), resolubilized proteins (pH 7), and membrane-concentrated clarified alfalfa juice. Dilute leaf protein solutions were prepared by dissolving these concentrates in water. Storage modulus (G ) of soluble leaf protein solutions as they gel was monitored with a cone-and-plate probe during temperature sweep from 25°C to 90°C

  11. 7 CFR 28.467 - Leaf Grade 7.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...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...

  12. 7 CFR 28.466 - Leaf Grade 6.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...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...

  13. 7 CFR 28.464 - Leaf Grade 4.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...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...

  14. 7 CFR 28.462 - Leaf Grade 2.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...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...

  15. 7 CFR 28.463 - Leaf Grade 3.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...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...

  16. 7 CFR 28.462 - Leaf Grade 2.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...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...

  17. 7 CFR 28.463 - Leaf Grade 3.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...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...

  18. 7 CFR 28.466 - Leaf Grade 6.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...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...

  19. 7 CFR 28.465 - Leaf Grade 5.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...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...

  20. 7 CFR 28.466 - Leaf Grade 6.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...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...

  1. 7 CFR 28.464 - Leaf Grade 4.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...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...

  2. 7 CFR 28.461 - Leaf Grade 1.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...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...

  3. 7 CFR 28.461 - Leaf Grade 1.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...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...

  4. 7 CFR 28.461 - Leaf Grade 1.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...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...

  5. 7 CFR 28.464 - Leaf Grade 4.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...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...

  6. 7 CFR 28.465 - Leaf Grade 5.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...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...

  7. 7 CFR 28.462 - Leaf Grade 2.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...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...

  8. 7 CFR 28.467 - Leaf Grade 7.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...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...

  9. 7 CFR 28.465 - Leaf Grade 5.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...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...

  10. 7 CFR 28.463 - Leaf Grade 3.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...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...

  11. 7 CFR 28.467 - Leaf Grade 7.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...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...

  12. Multiple Complexes of Nitrogen Assimilatory Enzymes in Spinach Chloroplasts: Possible Mechanisms for the Regulation of Enzyme Function

    PubMed Central

    Kimata-Ariga, Yoko; Hase, Toshiharu

    2014-01-01

    Assimilation of nitrogen is an essential biological process for plant growth and productivity. Here we show that three chloroplast enzymes involved in nitrogen assimilation, glutamate synthase (GOGAT), nitrite reductase (NiR) and glutamine synthetase (GS), separately assemble into distinct protein complexes in spinach chloroplasts, as analyzed by western blots under blue native electrophoresis (BN-PAGE). GOGAT and NiR were present not only as monomers, but also as novel complexes with a discrete size (730 kDa) and multiple sizes (>120 kDa), respectively, in the stromal fraction of chloroplasts. These complexes showed the same mobility as each monomer on two-dimensional (2D) SDS-PAGE after BN-PAGE. The 730 kDa complex containing GOGAT dissociated into monomers, and multiple complexes of NiR reversibly converted into monomers, in response to the changes in the pH of the stromal solvent. On the other hand, the bands detected by anti-GS antibody were present not only in stroma as a conventional decameric holoenzyme complex of 420 kDa, but also in thylakoids as a novel complex of 560 kDa. The polypeptide in the 560 kDa complex showed slower mobility than that of the 420 kDa complex on the 2D SDS-PAGE, implying the assembly of distinct GS isoforms or a post-translational modification of the same GS protein. The function of these multiple complexes was evaluated by in-gel GS activity under native conditions and by the binding ability of NiR and GOGAT with their physiological electron donor, ferredoxin. The results indicate that these multiplicities in size and localization of the three nitrogen assimilatory enzymes may be involved in the physiological regulation of their enzyme function, in a similar way as recently described cases of carbon assimilatory enzymes. PMID:25271437

  13. The function and properties of the iron-sulfur center in spinach ferredoxin: Thioredoxin reductase: A new biological role for iron-sulfur clusters

    SciTech Connect

    Staples, C.R.; Ameyibor, E.; Fu, Weiguang; Johnson, M.K. [Univ. of Georgia, Athens, GA (United States)] [and others] [Univ. of Georgia, Athens, GA (United States); and others

    1996-09-03

    Thioredoxin reduction in chloroplasts in catalyzed by a unique class of disulfide reductases which use a [2Fe-2S]{sup 2+/+} ferredoxin as the electron donor and contain an Fe-S cluster as the sole prosthetic group in addition to the active-site disulfide. The nature, properties, and function of the Fe-S cluster in spinach ferredoxin: thioredoxin reductase (FTR) have been investigated by the combination of UV/visible absorption, variable-temperature magnetic circular dichroism (MCD), EPR, and resonance Raman (RR) spectroscopies. 66 refs., 5 figs., 1 tab.

  14. Influence of leaf water status on leaf area index and leaf nitrogen concentration inversion of wheat canopy

    NASA Astrophysics Data System (ADS)

    Zhao, Chunjiang; Wang, Jihua; Huang, Wenjiang; Liu, Liangyun

    2005-01-01

    A field trial was conduct to investigate the relationship between spectral feature of winter wheat canopy and LAI as well as leaf nitrogen (N) under different status of leaf water in field situation. The objective of this study is to investigate effect of water status in plants on the accuracy of estimating leaf area index (LAI) and plant nitrogen. The new defined spectral index, IAFC = (R2224-R2054)/ (R2224+R2054), where R is the reflectance at 2224nm or 2054nm, was significantly (?=0.05) or extremely significantly (?=0.01) correlated with LAI at all the six dates for water insufficient plants, but not significantly correlated for water sufficient plants at five of the six dates and the difference of leaf water content between the water insufficient plants and water sufficient plants was only about 2% at some dates. The study provided strong evidence that leaf water has a strong masking effect on the 2000-2300nm spectral feature, which could be strongly associated with LAI and leaf N even when the leaf water content was as high as about 80% if the water was insufficient for plant growth. The results indicated that the masking effect of leaf water on the 2000-2300nm spectral feature was not only dependent on the absolute plant water content but also on the water status and that remotely sensed data in the 2000-2300nm region could be of potential in monitoring plant canopy biophysics and biochemistry in drought condition.

  15. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade...

  16. 7 CFR 28.471 - Below Leaf Grade Cotton.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade...

  17. Leaf element concentrations of terrestrial plants across China are

    E-print Network

    Slik, Ferry

    extracted from publications. The links between envi- ronmental variables, taxonomy and leaf elements wereRESEARCH PAPER Leaf element concentrations of terrestrial plants across China are influenced cycles of terrestrial eco- systems are strongly affected by leaf element concentrations. Understanding

  18. LSD: a leaf senescence database

    PubMed Central

    Liu, Xiaochuan; Li, Zhonghai; Jiang, Zhiqiang; Zhao, Yi; Peng, Jinying; Jin, Jinpu; Guo, Hongwei; Luo, Jingchu

    2011-01-01

    By broad literature survey, we have developed a leaf senescence database (LSD, http://www.eplantsenescence.org/) that contains a total of 1145 senescence associated genes (SAGs) from 21 species. These SAGs were retrieved based on genetic, genomic, proteomic, physiological or other experimental evidence, and were classified into different categories according to their functions in leaf senescence or morphological phenotypes when mutated. We made extensive annotations for these SAGs by both manual and computational approaches, and users can either browse or search the database to obtain information including literatures, mutants, phenotypes, expression profiles, miRNA interactions, orthologs in other plants and cross links to other databases. We have also integrated a bioinformatics analysis platform WebLab into LSD, which allows users to perform extensive sequence analysis of their interested SAGs. The SAG sequences in LSD can also be downloaded readily for bulk analysis. We believe that the LSD contains the largest number of SAGs to date and represents the most comprehensive and informative plant senescence-related database, which would facilitate the systems biology research and comparative studies on plant aging. PMID:21097471

  19. Wheat Leaf Rust Caused by Puccinia triticina

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Leaf rust, caused by Puccinia triticina, is the most common rust disease of wheat. The fungus is an obligate parasite capable of producing infectious urediniospores as long as the host remains healthy. Urediniospores can be wind-disseminated hundreds of kilometers and may result in wheat leaf rust e...

  20. EFFECTS OF DEOXYNIVALENOL ON BARLEY LEAF PIGMENTATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As a first step in characterizing the role deoxynivalenol (DON) plays in pathogenesis of Fusarium graminearum in leaf and head tissues, we treated detached barley leaf tissues with DON and examined them daily for signs of injury or other alterations. As shown here, DON had pronounced and unexpected ...

  1. 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 Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984, and 51 FR 25027,...

  2. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984, and 51 FR 25027,...

  3. 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 Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984, and 51 FR 25027,...

  4. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984, and 51 FR 25027,...

  5. 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 Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984, and 51 FR 25027,...

  6. Automobile leaf springs from composite materials

    Microsoft Academic Search

    H. A. Al-Qureshi

    2001-01-01

    The automobile industry has shown increased interest in the replacement of steel springs with fiberglass reinforced composite leaf springs. Therefore, the aim of this paper is to present a general study on the analysis, design and fabrication of composite springs. From this viewpoint, the suspension spring of a compact car, “a jeep” was selected as a prototype.A single leaf, variable

  7. Photovoltaic Leaf Area Meter Development and Testing

    Microsoft Academic Search

    C. Igathinathane; B. Chennakesavulu; K. Manohar; A. R. Womac; L. O. Pordesimo

    2008-01-01

    Photovoltaic (PV) panel was used to develop a simple and practical leaf area meter. Components of the developed PV leaf area meter include a PV panel as sensor, a wooden cabinet as enclosure, a flashlight as light source, and a commercial digital multimeter for voltage measurement. The principle of projected area measurement is the voltage generated by the PV panel

  8. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Agriculture 2 2014-01-01 2014-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations...Types 11, 12, 13, 14 and Foreign Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco....

  9. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations...Types 11, 12, 13, 14 and Foreign Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco....

  10. 7 CFR 29.1029 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations...Types 11, 12, 13, 14 and Foreign Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco....

  11. The red edge of plant leaf reflectance

    Microsoft Academic Search

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

    1983-01-01

    The red edge is the sharp change in leaf reflectance between 680 and 750 nm and has been measured on leaves of a variety of species by first derivative reflectance spectrophotometry. A parameter ?re was defined as the wavelength of maximum slope and found to be dependent on chlorophyll concentration (p<0.001), with additional effects of species, developmental stage, leaf layering

  12. Comparative enzymology of the adenosine triphosphate sulphurylases from leaf tissue of selenium-accumulator and non-accumulator plants.

    PubMed

    Shaw, W H; Anderson, J W

    1974-04-01

    1. ATP sulphurylases were partially purified (20-40-fold) from leaf tissue of Astragalus bisulcatus, Astragalus racemosus (selenium-accumulator species) and Astragalus hamosus and Astragalus sinicus (non-accumulator species). Activity was measured by sulphate-dependent PP(i)-ATP exchange. The enzymes were separated from pyrophosphatase and adenosine triphosphatase activities. The properties of the Astragalus ATP sulphurylases were similar to the spinach enzyme. 2. The ATP sulphurylases from both selenium-accumulator and non-accumulator species catalysed selenate-dependent PP(i)-ATP exchange; selenate competed with sulphate. The ratio of V(selenate)/V(sulphate) and K(m)(selenate)/K(m)(sulphate) was approximately the same for the enzyme from each species. 3. Sulphate-dependent PP(i)-ATP exchange was inhibited by ADP, chlorate and nitrate. The kinetics of the inhibition for each enzyme were consistent with an ordered reaction mechanism, in which ATP is the first substrate to react with the enzyme and PP(i) is the first product released. 4. Synthesis of adenosine 5'-[(35)S]sulphatophosphate from [(35)S]sulphate was demonstrated by coupling the Astragalus ATP sulphurylases with Mg(2+)-dependent pyrophosphatase; the reaction was inhibited by selenate. An analogous reaction using [(75)Se]selenate as substrate could not be demonstrated. PMID:4377098

  13. Comparative enzymology of the adenosine triphosphate sulphurylases from leaf tissue of selenium-accumulator and non-accumulator plants

    PubMed Central

    Shaw, W. H.; Anderson, J. W.

    1974-01-01

    1. ATP sulphurylases were partially purified (20–40-fold) from leaf tissue of Astragalus bisulcatus, Astragalus racemosus (selenium-accumulator species) and Astragalus hamosus and Astragalus sinicus (non-accumulator species). Activity was measured by sulphate-dependent PPi–ATP exchange. The enzymes were separated from pyrophosphatase and adenosine triphosphatase activities. The properties of the Astragalus ATP sulphurylases were similar to the spinach enzyme. 2. The ATP sulphurylases from both selenium-accumulator and non-accumulator species catalysed selenate-dependent PPi–ATP exchange; selenate competed with sulphate. The ratio of V(selenate)/V(sulphate) and Km(selenate)/Km(sulphate) was approximately the same for the enzyme from each species. 3. Sulphate-dependent PPi–ATP exchange was inhibited by ADP, chlorate and nitrate. The kinetics of the inhibition for each enzyme were consistent with an ordered reaction mechanism, in which ATP is the first substrate to react with the enzyme and PPi is the first product released. 4. Synthesis of adenosine 5?-[35S]sulphatophosphate from [35S]sulphate was demonstrated by coupling the Astragalus ATP sulphurylases with Mg2+-dependent pyrophosphatase; the reaction was inhibited by selenate. An analogous reaction using [75Se]selenate as substrate could not be demonstrated. PMID:4377098

  14. Same-Day Detection of Escherichia coli O157:H7 from Spinach by Using Electrochemiluminescent and Cytometric Bead Array Biosensors?

    PubMed Central

    Leach, Kelly M.; Stroot, Joyce M.; Lim, Daniel V.

    2010-01-01

    Contamination of fresh produce with Escherichia coli O157:H7 and other pathogens commonly causes food-borne illness and disease outbreaks. Thus, screening for pathogens is warranted, but improved testing procedures are needed to allow reproducible same-day detection of low initial contamination levels on perishable foods, and methods for detecting numerous pathogens in a single test are desired. Experimental procedures were developed to enable rapid screening of spinach for E. coli O157:H7 by using multiplex-capable immunological assays that are analyzed using biosensors. Detection was achieved using an automated electrochemiluminescent (ECL) assay system and a fluorescence-based cytometric bead array. Using the ECL system, less than 0.1 CFU of E. coli O157:H7 per gram of spinach was detected after 5 h of enrichment, corresponding to 6.5 h of total assay time. Using the cytometric bead array, less than 0.1 CFU/g was detected after 7 h of enrichment, with a total time to detection of less than 10 h. These results illustrate that both biosensor assays are useful for rapid detection of E. coli O157:H7 on produce in time frames that are comparable to or better than those of other testing formats. Both methods may be useful for multiplexed pathogen detection in the food industry and other testing situations. PMID:21037307

  15. Response of Leafy Vegetable Kalmi (Water Spinach; Ipomoea aquatica L.) at Elevated Concentrations of Arsenic in Hydroponic Culture

    Microsoft Academic Search

    Molla Rahman Shaibur; Tamanna Islam; Shigenao Kawai

    2009-01-01

    Effects of elevated arsenic (As) concentrations on hydroponic Kalmi (Ipomoea aquatica L.) were investigated. Plants were treated with 0, 10, 25, and 50 ?M As in the greenhouse for 14 days. Arsenic was added\\u000a from sodium meta-arsenite (NaAsO2). Visible toxicity symptom could not easily be recognized without visible growth reduction. Little brown spots on the leaf\\u000a blade were found at 50 ?M As

  16. 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

  17. Physiological, anatomical and leaf hydraulic effects on leaf water ?18O enrichment in different plant species

    NASA Astrophysics Data System (ADS)

    Kahmen, A.; Arndt, S. K.; Dawson, T. E.

    2007-12-01

    Stable oxygen isotope ratios (?18O) of plant and source waters are valuable tools in the analysis of water and carbon fluxes at leaf, plant, and ecosystem scales. Recent improvements in mechanistic models have significantly advanced the understanding of isotopic leaf water enrichment, which is an important source of ?18O variability in plants and ecosystems. However, the marked variability in leaf water ?18O values that have been reported for different plant species hampers efforts to interpret and then apply data on leaf water ?18O values for studies conducted at the ecosystem scale. To improve the understanding and application of ?18O values in leaf water, we tested the interplay of physiological, morphological, anatomical and leaf hydraulic properties as drivers of leaf water ?18O values across 17 Eucalyptus species growing in a common garden. We observed large differences in leaf water ?18O across the 17 species. These differences were only partly driven by physiological and leaf morphological differences across species. A sensitivity analysis using state-of-the-art leaf water enrichment models showed that the parameter - effective path length - (L) is of critical importance for the variability of leaf water ?18O across different species. The data show that L can be related to a suite of leaf properties that include physiology, anatomy and hydraulics. Consequently, consideration of leaf properties will significantly improve the interpretation of ?18O values in leaf water across different plant species and will therefore help in the application of ?18O values in carbon and water cycle assessments at both the plant and the ecosystem scale.

  18. Specific leaf area and leaf nitrogen concentration in annual and perennial grass species growing in Mediterranean old-fields

    Microsoft Academic Search

    E. Garnier; P. Cordonnier; J.-L. Guillerm; L. Sonié

    1997-01-01

    Specific leaf area (the ratio of leaf area to leaf dry mass) and leaf nitrogen concentration were measured on ten annual\\u000a and nine perennial grass species growing in two old-fields of southern France, under a sub-humid Mediterranean climate. Specific\\u000a leaf area (SLA) was found to be significantly higher in annuals than in perennials, but leaf nitrogen concentration expressed\\u000a on a

  19. 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

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

    PubMed

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

    2013-09-01

    During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models. PMID:24068091

  1. Leaf wax n-alkane ?D values of field-grown barley reflect leaf water ?D values at the time of leaf formation

    NASA Astrophysics Data System (ADS)

    Sachse, Dirk; Gleixner, Gerd; Wilkes, Heinz; Kahmen, Ansgar

    2010-12-01

    Leaf wax n-alkanes from barley ( Hordeum vulgare) from a field in Switzerland exhibited changes in ?D values on the order of 20‰ over a growing season, while source water (soil water) and leaf water varied by 40‰. Additionally the seasonal variability in ?D values of leaf wax n-alkanes of different barley leaves can only be found across different leaf generations (i.e. leaves that were produced at different times during the growing season) while n-alkane ?D values did not vary significantly within a leaf generation. Interestingly, ?D values of n-alkanes correlated best with the ?D values of leaf water at midday of the sampling day but showed no significant correlation with soil water (e.g. precipitation) ?D values. These results provide empirical evidence that leaf wax ?D values record leaf water enrichment, and therefore integrate the isotopic effects of precipitation and evapotranspiration. Our results show that leaf wax n-alkane ?D values from grasses are 'locked in' early during leaf development and hence record the environmental drivers of leaf water enrichment, such as vapor pressure deficit (VPD). Our data have important implications for the interpretation of paleorecords of leaf wax ?D. We suggest that leaf wax n-alkane ?D values from sedimentary records could be used to estimate changes in the degree of leaf water enrichment and hence VPD.

  2. Verticillium dahliae race 2-specific PCR reveals a high frequency of race 2 strains in commercial spinach seed lots and delineates race structure.

    PubMed

    Short, Dylan P G; Gurung, Suraj; Maruthachalam, Karunakaran; Atallah, Zahi K; Subbarao, Krishna V

    2014-07-01

    Two pathogenic races of Verticillium dahliae have been described on lettuce and tomato. Host resistance to race 1 is governed by plant immune receptors that recognize the race 1-specific fungal effector Ave1. Only partial resistance to race 2 exists in lettuce. Although polymerase chain reaction (PCR) assays are available to identify race 1, no complementary test exists to positively identify race 2, except for lengthy pathogenicity assays on host differentials. Using the genome sequences of two isolates of V. dahliae, one each from races 1 and 2, we identified potential markers and PCR primers to distinguish the two races. Several primer pairs based on polymorphisms between the races were designed and tested on reference isolates of known race. One primer pair, VdR2F-VdR2R, consistently yielded a 256-bp amplicon in all race 2 isolates exclusively. We screened DNA from 677 V. dahliae isolates, including 340 from spinach seedlots, with the above primer pair and a previously published race 1-specific primer pair. DNA from isolates that did not amplify with race 1-specific PCRs amplified with the race 2-specific primers. To validate this, two differential lines of lettuce were inoculated with 53 arbitrarily selected isolates from spinach seed and their pathogenicity and virulence were assessed in a greenhouse. The reactions of the differential cultivars strongly supported the PCR data. V. dahliae race structure was investigated in crops in coastal California and elsewhere using primers specific to the two races. All artichoke isolates from California were race 1, whereas nearly all tomato isolates were race 2. Isolates from lettuce, pepper, and strawberry from California as well as isolates from spinach seed from two of four countries comprised both races, whereas only race 2 was observed in cotton, mint, olive, and potato. This highlights the importance of identifying resistance against race 2 in different hosts. The technique developed in this study will benefit studies in ecology, population biology, disease surveillance, and epidemiology at local and global scales, and resistance breeding against race 2 in lettuce and other crops. PMID:24502204

  3. 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…

  4. Purdue extensionGray Leaf Spot Purdue extension

    E-print Network

    1 Purdue extensionGray Leaf Spot BP-56-W Purdue extension d i s e a s e s o f c o r n Gray Leaf. Severeleaftissueblightingcanoccurandresultinyieldloss. Gray leaf spot on corn, caused by the fungus Cercospora zeae-maydis, is a peren- nial susceptibility and weather strongly influence disease develop- ment, which is why gray leaf spot can be locally

  5. 7 CFR 28.511 - Leaf Grade No. 1.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...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...

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

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...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...

  7. INTRODUCTION The maize leaf is a photosynthetic organ comprising three

    E-print Network

    Pawlowski, Wojtek

    INTRODUCTION The maize leaf is a photosynthetic organ comprising three basic parts; the proximal. The leaf is one component of a phytomer, the basic, repeating structural unit of the maize plant (Galinat prophyll), the node, and the leaf. In maize, the tubular base of the leaf extends into the node

  8. 7 CFR 28.512 - Leaf Grade No. 2.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...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...

  9. 7 CFR 28.513 - Leaf Grade No. 3.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...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...

  10. 7 CFR 28.514 - Leaf Grade No. 4.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...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...

  11. 7 CFR 28.512 - Leaf Grade No. 2.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...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...

  12. 7 CFR 28.514 - Leaf Grade No. 4.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...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...

  13. 7 CFR 28.515 - Leaf Grade No. 5.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...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...

  14. 7 CFR 28.514 - Leaf Grade No. 4.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...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...

  15. Leaf litter ant diversity in Guyana JOHN S. LAPOLLA1,

    E-print Network

    Schultz, Ted

    -1 Leaf litter ant diversity in Guyana JOHN S. LAPOLLA1, *, TED SUMAN1 , JEFFREY SOSA-CALVO1 Shield, Leaf litter ants Abstract. Leaf litter ants are an important group of organisms for informing conservation plan- ning. This study presents the beginning of a leaf litter ant dataset for Guyana. Following

  16. 7 CFR 28.515 - Leaf Grade No. 5.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...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...

  17. 7 CFR 28.515 - Leaf Grade No. 5.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...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...

  18. 7 CFR 28.513 - Leaf Grade No. 3.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...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...

  19. Leaf Deformation Taking Into Account Fluid Flow Paulo Silva

    E-print Network

    Ouhyoung, Ming

    Leaf Deformation Taking Into Account Fluid Flow Paulo Silva The University of Tokyo Yonghao Yue--This paper proposes a method for animating leaf structural deformation considering the leaf water content the leaf, and couple the mass-spring parameters with a simulation representing the fluid flow

  20. 7 CFR 28.511 - Leaf Grade No. 1.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...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...

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

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...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...

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

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 2014-01-01 2014-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...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...

  3. 7 CFR 28.516 - Leaf Grade No. 6.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...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...

  4. 7 CFR 28.512 - Leaf Grade No. 2.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 2012-01-01 2012-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...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...

  5. 7 CFR 28.513 - Leaf Grade No. 3.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 2013-01-01 2013-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...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...

  6. Effect of Image Processing of a Leaf Photograph on the Calculated Fractal Dimension of Leaf Veins

    Microsoft Academic Search

    Yun Kong; Shaohui Wang; Chengwei Ma; Baoming Li; Yuncong Yao

    2007-01-01

    Digital photography is a promised method for estimating the fractal characteristics of leaf veins. In this study, the effects\\u000a of different threshold levels and image processing methods using Adobe Photoshop software on the fractal dimension values\\u000a were examined from a digital photo of nectarine leaf. The results showed that the nectarine leaf vein has typical fractal\\u000a characteristics and its fractal

  7. Short communication Leaf optical properties and photosynthetic leaf absorptances in several Australian seagrasses

    Microsoft Academic Search

    Michael J. Durako

    Thisstudyinvestigated within-and among-species variability intheleafoptical properties ofeightlarge-bodiedseagrasses,Posidoniaaustralis, Posidonia sinuosa, Posidonia coriacea, Posidonia angustifolia, Amphibolis antarctica, Amphibolis griffithii, Zostera tasmanica, and Zostera capricorni and the small-bodied Halophila ovalis from the east and west coasts of Australia. Leaf spectral transmittance (TL(l)), reflectance (RL(l)), and non-photosynthetic absorptance (AL(NP)) were measured in order to calculate leaf spectral absorptance (AL(l)) and photosynthetic leaf absorptance (AL(PAR)).

  8. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell...

  9. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell...

  10. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell...

  11. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell...

  12. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell...

  13. How a leaf gets its shape.

    PubMed

    Moon, Jihyun; Hake, Sarah

    2011-02-01

    Leaves are formed from a group of initial cells within the meristem. One of the earliest markers of leaf initiation is the down-regulation of KNOX genes in initial cells. Polar auxin activity, MYB and LOB domain transcription factors function to keep KNOX out of the initiating leaf. If KNOX genes are expressed in initial cells, leaves fail to form. As the leaf grows away from the meristem, its shape is determined by growth in three axes, proximal-distal, abaxial-adaxial and medial-lateral. HD-ZIPIII, KANADI and the small RNA pathway play a significant role in the latter two axes. KNOX proteins play a role in the proximal-distal axis. Although genetic networks are conserved between monocots and dicots, the outcome in leaf shape often differs. PMID:20870452

  14. 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.

  15. 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.

  16. 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)

  17. 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.

  18. How cellulose-based leaf toughness and lamina density contribute to long leaf lifespan of shade tolerant species

    E-print Network

    Kitajima, Kaoru

    and methanol extraction. Leaf dry mass content (LDMC) was determined by dividing dry mass by fresh mass for #12How cellulose-based leaf toughness and lamina density contribute to long leaf For cutting test, each fresh leaf disk was trimmed and oriented so that the cutting pass was sufficiently long

  19. The effect of elevated CO2 on diel leaf growth cycle, leaf carbohydrate content and canopy growth

    E-print Network

    Barron-Gafford, Greg

    The effect of elevated CO2 on diel leaf growth cycle, leaf carbohydrate content and canopy growth the effect of elevated CO2 on the diel leaf growth cycle for the first time in a dicot plant. Growing leaves at dusk. At the beginning of the season, leaf growth did not differ between treatments. At the end

  20. Summary Leaf structure has been shown to be an important determinant of leaf photosynthetic characteristics, yet the na-

    E-print Network

    Green, Scott

    Summary Leaf structure has been shown to be an important determinant of leaf photosynthetic characteristics, yet the na- ture of this relationship remains ambiguous. It has been sug- gested that intra-leaf shading of chloroplasts may explain the negative influence of increasing leaf thickness/density on mass

  1. Ginseng leaf-stem: bioactive constituents and pharmacological functions

    Microsoft Academic Search

    Hongwei Wang; Dacheng Peng; Jingtian Xie

    2009-01-01

    Ginseng root is used more often than other parts such as leaf stem although extracts from ginseng leaf-stem also contain similar active ingredients with pharmacological functions. Ginseng's leaf-stems are more readily available at a lower cost than its root. This article reviews the pharmacological effects of ginseng leaf-stem on some diseases and adverse effects due to excessive consumption. Ginseng leaf-stem

  2. Zesty Spinach Omelet Ingredients

    E-print Network

    Liskiewicz, Maciej

    into small pieces. Set aside. 3. Crack egg into a small bowl and check for freshness. If it is OK, add large eggs 2 tablespoons water Dash cumin Dash salt Dash pepper Non stick cooking spray 1/4 cup salsa to bowl. Repeat for other egg. Use a fork to beat eggs together. 4. Mix in water, cumin, salt and pepper

  3. Quick Spinach Lasagna Ingredients

    E-print Network

    Liskiewicz, Maciej

    ounces low sodium tomatoes, canned 1 1/2 cups water 1/4 teaspoon garlic powder 1/2 teaspoon oregano 1 and cook until tender, about 5 minutes. 5. Add turkey, tomatoes, water, garlic powder, oregano, and basil

  4. Nutrient influences on leaf photosynthesis

    SciTech Connect

    Longstreth, D.J.; Nobel, P.S.

    1980-01-01

    The net rate of CO/sub 2/ uptake for leaves of Gossypium hirsutum L. was reduced when the plants were grown at low concentrations of NO/sub 3//sup -/, PO/sub 4//sup 2 -/, or K/sup +/. The water vapor conductance was relatively constant for all nutrient levels, indicating little effect on stomatal response. Although leaves under nutrient stress tended to be lower in chlorophyll and thinner, the ratio of mesophyll surface area to leaf area did not change appreciably. Thus, the reduction in CO/sub 2/ uptake rate at low nutrient levels was due to a decrease in the CO/sub 2/ conductance expressed per unit mesophyll cell wall area (g/sub CO/sup cell//sub 2/). The use of g/sub CO//sup cell//sub 2/ and nutrient levels expressed per unit of mesophyll cell wall provides a new means of assessing nutrient effects on CO/sub 2/ uptake of leaves. 14 figures, 1 table.

  5. Root Hypoxia Reduces Leaf Growth 1

    PubMed Central

    Smit, Barbara A.; Neuman, Dawn S.; Stachowiak, Matthew L.

    1990-01-01

    This study examined the potential role of restricted phloem export, or import of substances from the roots in the leaf growth response to root hypoxia. In addition, the effects of root hypoxia on abscisic acid (ABA) and zeatin riboside (ZR) levels were measured and their effects on in vitro growth determined. Imposition of root hypoxia in the dark when transpirational water flux was minimal delayed the reduction in leaf growth until the following light period. Restriction of phloem transport by stem girdling did not eliminate the hypoxia-induced reduction in leaf growth. In vitro growth of leaf discs was inhibited in the presence of xylem sap collected from hypoxic roots, and also by millimolar ABA. Disc growth was promoted by sap from aerated roots and by 0.1 micromolar ZR. The flux of both ABA and ZR was reduced in xylem sap from hypoxic roots. Leaf ABA transiently increased twofold after 24 hours of hypoxia exposure but there were no changes in leaf cytokinin levels. Images Figure 3 Figure 4 PMID:16667366

  6. Determination of six neonicotinoid insecticides residues in spinach, cucumber, apple and pomelo by QuEChERS method and LC-MS/MS.

    PubMed

    Zhang, Fengzu; Li, Yanjie; Yu, Chuanshan; Pan, Canping

    2012-06-01

    A modified QuEChERS and LC-MS/MS method has been developed for the simultaneous determination of residues of six neonicotinoids in various crops, including spinach, cucumber, apple and pomelo. The method showed good linearity (R(2) ? 0.9995) and precision (RSD ? 14.0%). Average recoveries of the six neonicotinoids ranged between 73.7% and 103.8% at spiking levels 0.005, 0.1 and 1 mg kg(-1). The LODs and LOQs were in the ranges of 0.20-0.85 ?g kg(-1) and 0.66-2.84 ?g kg(-1), respectively. The method was satisfactorily validated for the analysis of 50 agricultural samples. Imidacloprid and imidaclothiz were detected at concentration levels ranging from 7 to 5.3 ?g kg(-1). PMID:22398693

  7. Metabolism and decarboxylation of glycollate and serine in leaf peroxisomes

    Microsoft Academic Search

    Nicholas J. Walton; Vernon S. Butt

    1981-01-01

    The linked utilization of glycollate and L-serine has been studied in peroxisomal preparations from leaves of spinach beet (Beta vulgaris L.). The generation of glycine from glycollate was found to be balanced by the production of hydroxypyruvate from serine and similarly by 2-oxoglutarate when L-glutamate was substituted for L-serine. In the presence of L-malate and catalytic quantities of NAD+, about

  8. Isolation of Campylobacter from feral swine (Sus scrofa) on the ranch associated with the 2006 Escherichia coli O157:H7 spinach outbreak investigation in California.

    PubMed

    Jay-Russell, M T; Bates, A; Harden, L; Miller, W G; Mandrell, R E

    2012-08-01

    We report the isolation of Campylobacter species from the same population of feral swine that was investigated in San Benito County, California, during the 2006 spinach-related Escherichia coli O157:H7 outbreak. This is the first survey of Campylobacter in a free-ranging feral swine population in the United States. Campylobacter species were cultured from buccal and rectal-anal swabs, colonic faeces and tonsils using a combination of selective enrichment and antibiotic-free membrane filtration methods. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS, Bruker Daltonics, Inc., Billerica, MA, USA) was used to identify species followed by confirmatory multiplex PCR or 16S rRNA sequencing. Genetic relatedness of Campylobacter jejuni and Campylobacter coli strains was determined by multilocus sequence typing (MLST) and porA allele sequencing. Altogether, 12 (40%) of 30 feral swine gastrointestinal and oral cavity specimens were positive, and six species were isolated: Campylobacter coli, Campylobacter fetus, Campylobacter hyointestinalsis, Campylobacter jejuni, Campylobacter lanienae and Campylobacter sputorum. Campylobacter jejuni subtypes were closely related to MLST sequence type 21 (ST-21) and had identical porA sequences. Campylobacter coli subtypes were unrelated to isolates in the pubMLST/porA database. This feral swine population lived in close association with a 'grassfed' beef cattle herd adjacent to spinach and other leafy green row crop fields. The findings underscore the importance of protecting raw vegetable crops from faecal contamination by wild or feral animals. The study also illustrates a potential risk of Campylobacter exposure for hunters during handling and processing of wild swine meat. PMID:22405465

  9. Decline of leaf hydraulic conductance with dehydration: relationship to leaf size and venation architecture.

    PubMed

    Scoffoni, Christine; Rawls, Michael; McKown, Athena; Cochard, Hervé; Sack, Lawren

    2011-06-01

    Across plant species, leaves vary enormously in their size and their venation architecture, of which one major function is to replace water lost to transpiration. The leaf hydraulic conductance (K(leaf)) represents the capacity of the transport system to deliver water, allowing stomata to remain open for photosynthesis. Previous studies showed that K(leaf) relates to vein density (vein length per area). Additionally, venation architecture determines the sensitivity of K(leaf) to damage; severing the midrib caused K(leaf) and gas exchange to decline, with lesser impacts in leaves with higher major vein density that provided more numerous water flow pathways around the damaged vein. Because xylem embolism during dehydration also reduces K(leaf), we hypothesized that higher major vein density would also reduce hydraulic vulnerability. Smaller leaves, which generally have higher major vein density, would thus have lower hydraulic vulnerability. Tests using simulations with a spatially explicit model confirmed that smaller leaves with higher major vein density were more tolerant of major vein embolism. Additionally, for 10 species ranging strongly in drought tolerance, hydraulic vulnerability, determined as the leaf water potential at 50% and 80% loss of K(leaf), was lower with greater major vein density and smaller leaf size (|r| = 0.85-0.90; P < 0.01). These relationships were independent of other aspects of physiological and morphological drought tolerance. These findings point to a new functional role of venation architecture and small leaf size in drought tolerance, potentially contributing to well-known biogeographic trends in leaf size. PMID:21511989

  10. Sucrose Accumulation in the Sugarcane Stem 1s Regulated by the Difference between the Activities of Soluble Acid Invertase and Sucrose Phosphate Synthase

    Microsoft Academic Search

    Yun J. Zhu; Ewald Komor; Paul H. Moore

    To asses the relative importance of morphological and biochem- ical factors in the regulation of sucrose (Suc) accumulation in the sugarcane (Saccharum spp. hybrids) stem, we investigated morpho- logical and biochemical correlates of Suc accumulation among parents and progeny of a family segregating for differences. In contrast to the parents, no relationship was observed between morphology and the level of

  11. Elevated Levels of Both Sucrose-Phosphate Synthase and Sucrose Synthase in Vicia Guard Cells Indicate Cell-Specific Carbohydrate Interconversions.

    PubMed Central

    Hite, DRC.; Outlaw, W. H.; Tarczynski, M. C.

    1993-01-01

    A long series of reports correlate larger stomatal aperture size with elevated concentration of sucrose (Suc) in guard cells. To assess the role and autonomy of guard cells with respect to these changes, we have determined quantitatively the cellular distribution of the synthetic enzyme, Suc-phosphate synthase (SPS) and the degradative enzyme Suc synthase (SS) in Vicia leaflet. As expected for Suc-exporting cells, the photosynthetic parenchyma had a high SPS:SS ratio of approximately 45. Also as expected, in epidermal cells, which had only few and rudimentary plastids, the SPS:SS ratio was low (0.4). Of all cells and tissues measured, those that had the highest specific activity of SPS (about 4.8 [mu]mol mg-1 of protein h-1) were guard cells. Guard cells also had a very high relative specific activity of SS. PMID:12231776

  12. Elevated levels of both sucrose-phosphate synthase and sucrose synthase in vicia guard cells indicate cell-specific carbohydrate interconversions

    SciTech Connect

    Hite, D.R.C.; Outlaw, W.H. Jr.; Tarczynski, M.C. (Florida State Univ., Tallahassee (United States))

    1993-04-01

    A long series of reports correlate larger stomatal aperture size with elevated concentration of sucrose (Suc) in guard cells. To assess the role and autonomy of guard cells with respect to these changes, the authors have determined quantitatively the cellular distribution of the synthetic enzyme, Suc-phosphate synthase (SPS) and the degradative enzyme Suc synthase (SS) in Vicia leaflet. As expected for Suc-exporting cells, the photosynthetic parenchyma had a high SPS:SS ratio of approximately 45. Also as expected, in epdermal cells, which had only few and rudimentary plastids, the SPS:SS ratio was low (0.4). Of all cells and tissues measured, those that had the highest specific activity of SPS (about 4.8 [mu]mol mg[sup [minus]1] of protein h[sup [minus]1]) were guard cells. Guard cells also had a very high relative specific activity of SS. 45 refs., 3 figs.

  13. Fabrication of biomimetic superhydrophobic surfaces inspired by lotus leaf and silver ragwort leaf

    Microsoft Academic Search

    Jinyou Lin; Yu Cai; Xianfeng Wang; Bin Ding; Jianyong Yu; Moran Wang

    2011-01-01

    Inspired by the self-cleaning lotus leaf and silver ragwort leaf, here we demonstrate the fabrication of biomimetic superhydrophobic fibrous mats via electrospinning polystyrene (PS) solution in the presence of silica nanoparticles. The resultant electrospun fiber surfaces exhibited a fascinating structure with the combination of nano-protrusions and numerous grooves due to the rapid phase separation in electrospinning. The content of silica

  14. Specific leaf area and leaf dry matter content of plants growing in sand dunes

    Microsoft Academic Search

    Yulin LI; Douglas A. JOHNSON; Yongzhong SU; Jianyuan CUI; Tonghui ZHANG

    2005-01-01

    We investigated the variations in specific leaf area (SLA) and leaf dry matter content (LDMC) of 20 species (10 annuals and 10 perennials) that have different distributional patterns in the Kerqin Sandy Land in north- ern China. The main purpose of our study was to determine if SLA and\\/or LDMC could be used as indicators of plant resource-use strategy in

  15. Coffee leaf volatiles and egg laying by the coffee leaf miner Leucoptera coffeella

    Microsoft Academic Search

    Sérgio Tinôco V. Magalhães; Raul Narciso C. Guedes; Eraldo R. Lima; Antonio J. Demuner

    2008-01-01

    Recent reports of coffee genotypes resistant to one of its key pests in the Neotropical region, the leaf miner Leucoptera coffeella (Lepidoptera: Lyonetiidae), sparked studies trying to recognize the underlying causes of resistance. An association between increased egg laying by the leaf miner and increased caffeine levels in coffee leaves was recently recognized. However, since caffeine is not volatile, its

  16. Leaf lifespan as a determinant of leaf structure and function among 23 amazonian tree species

    Microsoft Academic Search

    P. B. Reich; C. Uhl; M. B. Walters; D. S. Ellsworth

    1991-01-01

    The relationships between resource availability, plant succession, and species' life history traits are often considered key to understanding variation among species and communities. Leaf lifespan is one trait important in this regard. We observed that leaf lifespan varies 30-fold among 23 species from natural and disturbed communities within a 1-km radius in the northern Amazon basin, near San Carlos de

  17. Stomatal Closure during Leaf Dehydration, Correlation with Other Leaf Physiological Traits1

    E-print Network

    Holbrook, N. Michele

    functions of the leaf to determine which responds most similarly to stomata during desiccation. Leaf of embolisms. Stomata appear in the fossil record approximately 400 million years ago (Edwards et al., 1998 of stomatal clo- sure, the fundamental question of why stomata close remains unanswered. Given that stomata

  18. 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.

  19. The Scaling Relationships between Leaf Mass and Leaf Area of Vascular Plant Species Change with Altitude

    PubMed Central

    Pan, Sha; Liu, Chao; Zhang, Weiping; Xu, Shanshan; Wang, Nan; Li, Yan; Gao, Jing; Wang, Yang; Wang, Genxuan

    2013-01-01

    The scaling relationship between leaf dry mass and leaf surface area has important implications for understanding the ability of plants to harvest sunlight and grow. Whether and how the scaling relationships vary across environmental gradients are poorly understood. We analyzed the scaling relationships between leaf mass and leaf area of 121 vascular plant species along an altitudinal gradient in a subtropical monsoon forest. The slopes increased significantly with altitude, it varied from less than 1 at low altitude to more than 1 at high altitude. This means that plants growing at high altitude allocate proportionately more biomass to support tissues in larger leaves and less in smaller leaves, whereas the reverse is true at low altitude. This pattern can be explained by different leaf strategies in response to environmental pressure and constrains. PMID:24146938

  20. In vitro response of leaf tissues from Lolium multiflorum — a comparison with leaf segment position, leaf age and in vivo mitotic activity

    Microsoft Academic Search

    O. I. Joarder; N. H. Joarder; P. J. Dale

    1986-01-01

    Immature gramineous leaves provide a convenient system for comparing the response of cells in culture with their state of differentiation. Callusing frequency is compared with leaf segment position, leaf age and in vivo mitotic activity in Lolium multiflorum. (1) In a succession of one millimeter sections from the immature leaf base, callus was formed from the first and second sections

  1. Role of chloroplastidial proteases in leaf senescence

    PubMed Central

    Goud, Prashanth B

    2011-01-01

    In this report the effect of hydrogen peroxide (H2O2) on peroxidase (POD) activity during leaf senescence was studied with and without phenylmethylsulfonyl fluoride (PMSF) pre-treatment in detached neem (Azadirachta indica A. juss) leaf chloroplasts. Increased POD activity was detected in natural and H2O2-promoted senescent leaf chloroplasts compared to untreated control mature green leaf chloroplasts. However, under H2O2 POD activity markedly increased at 1 day, and then significantly decreased until 4 days. In the presence of H2O2, PMSF, the induction of POD activity was alleviated at 1 day, whereas reduced after 4 days. In contrast, in the presence of H2O2, cycloheximide (CX), the induction of POD activity was reduced at 1 day, whereas alleviated after 4 days. The was a partial reduction in H2O2-induced POD activity with PMSF and CX, indicating the presence of pre-existing inactive PODs in chloroplasts. We also propose a new role for chloroplastidial proteases as activators of pre-existing inactive PODs during leaf senescence. PMID:22024830

  2. Persimmon leaf flavonoid promotes brain ischemic tolerance

    PubMed Central

    Miao, Mingsan; Zhang, Xuexia; Bai, Ming; Wang, Linan

    2013-01-01

    Persimmon leaf flavonoid has been shown to enhance brain ischemic tolerance in mice, but its mechanism of action remains unclear. The bilateral common carotid arteries were occluded using a micro clip to block blood flow for 10 minutes. After 10 minutes of ischemic preconditioning, 200, 100, and 50 mg/kg persimmon leaf flavonoid or 20 mg/kg ginaton was intragastrically administered per day for 5 days. At 1 hour after the final administration, ischemia/reperfusion models were estab-lished by blocking the middle cerebral artery for 2 hours. At 24 hours after model establishment, compared with cerebral ischemic rats without ischemic preconditioning or drug intervention, plasma endothelin, thrombomodulin and von Willebrand factor levels significantly decreased and intercel-lular adhesion molecule-1 expression markedly reduced in brain tissue from rats with ischemic pre-conditioning. Simultaneously, brain tissue injury reduced. Ischemic preconditioning combined with drug exposure noticeably improved the effects of the above-mentioned indices, and the effects of 200 mg/kg persimmon leaf flavonoid were similar to 20 mg/kg ginaton treatment. These results indicate that ischemic preconditioning produces tolerance to recurrent severe cerebral ischemia. However, persimmon leaf flavonoid can elevate ischemic tolerance by reducing inflammatory reactions and vascular endothelial injury. High-dose persimmon leaf flavonoid showed an identical effect to ginaton. PMID:25206573

  3. 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).

  4. 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 (?D) of plant leaf wax is a powerful tool to study the hydrology of past and present environments. The ?D value of leaf waxes is known to primarily reflect the ?D 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 ?D 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 ?D 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 ?D 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 ?D 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 water isotopic enrichment and larger net fractionations during these greenhouse conditions. Future work involving transgenic plants holds considerable potential to isolate additional factors which may influence the net fractionation between source water and leaf waxes adding to our fundamental understanding of this proxy.

  5. www.growit.umd.edu Home and Garden Information Center 12005 Homewood Road Ellicott City, MD 21042 www.hgic.umd.edu

    E-print Network

    Hill, Wendell T.

    and sand tend to catch in the crinkles of the leaves. Other types of spinach include perpetual spinach. Cultivation: · Fertilizing ­ Spinach is a heavy feeder. Incorporate lots of compost or 3 tablespoons of 10 in salads or sautéed. · Specialdirections ­ Use floating row covers to exclude spinach leaf miners

  6. Leaf Diffusion Resistance, Illuminance, and Transpiration 1

    PubMed Central

    Ehrler, W. L.; van Bavel, C. H. M.

    1968-01-01

    Stepwise increases in fluorescent illuminance, imposed as a single variable in a controlled environment, induced progressive stomatal opening in 8 plant species, as evidenced by a consistent decrease in leaf diffusion resistance (RL), ranging from 15 to 70 sec cm?1 in darkness to about 1 sec cm?1 at approximately 40 kilolux. The minimum RL values were the same for the upper and the lower epidermis, provided that stomatal density was adequate. Saturation illuminance was not achieved in any species; extrapolation indicates that 50 kilolux would bring about full stomatal opening (RL ? 0.1 sec cm?1). In 4 species, reasonable agreement was obtained in a controlled environment between transpiration as measured by weight loss and that calculated from determination of (a) the difference in water vapor density from leaf to air, (b) the boundary layer resistance, and (c) the leaf diffusion resistance. This result confirms the physical validity of the resistance measurement procedure. PMID:16656753

  7. A Polygalacturonase from Citrus Leaf Explants

    PubMed Central

    Riov, J.

    1974-01-01

    The relationship between polygalacturonase activity and abscission of citrus leaf explants was studied. Determination of polygalacturonase activity in citrus tissues requires concentration of the enzyme, use of a proper assay method, and inhibition of an oxidase present in the extracts which oxidizes the reaction products of the polygalacturonase. The polygalacturonase from citrus leaf explants is an exopolygalacturonase and appears to be a soluble enzyme. Polygalacturonase activity increased during abscission of citrus leaf explants and was localized in the separation layer. Ethylene accelerated the increase in polygalacturonase activity, but its effect was evident only after at least an 8-hour lag period. 2,4-Dichlorophenoxyacetic acid and cycloheximide inhibited abscission and polygalacturonase activity. It is concluded that polygalacturonase, in addition to cellulase, plays a role in abscission. Images PMID:16658697

  8. An evaluation of direct and indirect mechanisms for the “sink-regulation” of photosynthesis in spinach: Changes in gas exchange, carbohydrates, metabolites, enzyme activities and steady-state transcript levels after cold-girdling source leaves

    Microsoft Academic Search

    Anne Krapp; Mark Stitt

    1995-01-01

    Mature source leaves of spinach (Spinacia oleracea L.) plants growing hydroponically in a 9 h light (350 µmol photons·m-2 · s-1)\\/15 h dark cycle at 20° C in a climate chamber were fitted with a cold girdle around the petiole, 2 h into the light period. Samples were taken 1, 3 and 7 h later, and at the end of

  9. Leaf-level nitrogen use efficiency: definition and importance.

    PubMed

    Hirose, Tadaki

    2012-07-01

    Nitrogen use efficiency (NUE) has been widely used to study the relationship between nitrogen uptake and dry mass production in the plant. As a subsystem of plant nitrogen use efficiency (NUE), I have defined leaf-level NUE as the surplus production (gross production minus leaf respiration) per unit amount of nitrogen allocated to the leaf, with factorization into leaf nitrogen productivity (NP) and mean residence time of leaf nitrogen (MRT). These concepts were applied to two herbaceous stands: a perennial Solidago altissima stand and an annual Amaranthus patulus stand. S. altissima had more than three times higher leaf NUE than A. patulus due to nearly three times longer MRT of leaf N. In both species, NUE and NP were higher at the leaf level than at the plant level, because most leaf N is involved directly in the photosynthetic activity and because leaf surplus production is higher than the plant net production. MRT was longer at the plant level. The more than twice as long MRT at the plant level as at the leaf level in S. altissima was due to a large contribution of nitrogen storage belowground in the winter in this species. Thus, comparisons between a perennial and an annual system and between plant- and leaf-level NUE with their components revealed the importance of N allocation, storage, recycling, and turnover of organs for leaf photosynthetic production and plant dry mass growth. PMID:22179330

  10. Leaf-to-leaf distances and their moments in finite and infinite m-ary tree graphs

    E-print Network

    Andrew M. Goldsborough; S. Alex Rautu; Rudolf A. Römer

    2015-04-17

    We study the leaf-to-leaf distances on full and complete m-ary graphs using a recursive approach. In our formulation, leaves are ordered along a line. We find explicit analytical formulae for the sum of all paths for arbitrary leaf-to-leaf distance r as well as the average path lengths and the moments thereof. We show that the resulting explicit expressions can be recast in terms of Hurwitz-Lerch transcendants. Results for periodic trees are also given. For incomplete random binary trees, we provide first results by numerical techniques; we find a rapid drop of leaf-to-leaf distances for large r.

  11. Perfect is best: low leaf fluctuating asymmetry reduces herbivory by leaf miners.

    PubMed

    Cornelissen, Tatiana; Stiling, Peter

    2005-01-01

    Fluctuating asymmetry (FA) represents small, random variation from symmetry and can be used as an indicator of plant susceptibility to herbivory. We investigated the effects of FA of two oak species, Quercus laevis and Q. geminata, and the responses of three herbivore guilds: leaf miners, gallers, and chewers. To examine differences in FA and herbivory between individuals, 40 leaves from each tree were collected, and FA indices were calculated. To examine differences in FA and herbivory within-individuals, we sampled pairs of mined and unmined leaves for asymmetry measurements. Differences in growth of leaf miners between leaf types were determined by tracing 50 mines of each species on symmetric leaves and asymmetric leaves. Asymmetric leaves contained significantly lower concentrations of tannins and higher concentrations of nitrogen than symmetric leaves for both plant species. Both frequency of asymmetric leaves on plants and levels of asymmetry positively influenced the abundance of Brachys, Stilbosis and other leaf miners, but no significant relationship between asymmetry and herbivory was observed for Acrocercops. Brachys and Stilbosis mines were smaller on asymmetric leaves, but differences in mine survivorship between symmetric and asymmetric leaves were observed only for Stilbosis mines. This study indicated that leaf miners might use leaf FA as a cue to plant quality, although differential survivorship among leaf types was not observed for all species studied. Reasons for the different results between guilds are discussed. PMID:15378348

  12. 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.

  13. Is leaf dry matter content a better predictor of soil fertility than specific leaf area?

    PubMed Central

    Hodgson, J. G.; Montserrat-Martí, G.; Charles, M.; Jones, G.; Wilson, P.; Shipley, B.; Sharafi, M.; Cerabolini, B. E. L.; Cornelissen, J. H. C.; Band, S. R.; Bogard, A.; Castro-Díez, P.; Guerrero-Campo, J.; Palmer, C.; Pérez-Rontomé, M. C.; Carter, G.; Hynd, A.; Romo-Díez, A.; de Torres Espuny, L.; Royo Pla, F.

    2011-01-01

    Background and Aims Specific leaf area (SLA), a key element of the ‘worldwide leaf economics spectrum’, is the preferred ‘soft’ plant trait for assessing soil fertility. SLA is a function of leaf dry matter content (LDMC) and leaf thickness (LT). The first, LDMC, defines leaf construction costs and can be used instead of SLA. However, LT identifies shade at its lowest extreme and succulence at its highest, and is not related to soil fertility. Why then is SLA more frequently used as a predictor of soil fertility than LDMC? Methods SLA, LDMC and LT were measured and leaf density (LD) estimated for almost 2000 species, and the capacity of LD to predict LDMC was examined, as was the relative contribution of LDMC and LT to the expression of SLA. Subsequently, the relationships between SLA, LDMC and LT with respect to soil fertility and shade were described. Key Results Although LD is strongly related to LDMC, and LDMC and LT each contribute equally to the expression of SLA, the exact relationships differ between ecological groupings. LDMC predicts leaf nitrogen content and soil fertility but, because LT primarily varies with light intensity, SLA increases in response to both increased shade and increased fertility. Conclusions Gradients of soil fertility are frequently also gradients of biomass accumulation with reduced irradiance lower in the canopy. Therefore, SLA, which includes both fertility and shade components, may often discriminate better between communities or treatments than LDMC. However, LDMC should always be the preferred trait for assessing gradients of soil fertility uncoupled from shade. Nevertheless, because leaves multitask, individual leaf traits do not necessarily exhibit exact functional equivalence between species. In consequence, rather than using a single stand-alone predictor, multivariate analyses using several leaf traits is recommended. PMID:21948627

  14. 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.

  15. Vlasov equation on a symplectic leaf

    NASA Astrophysics Data System (ADS)

    David Crawford, John; Hislop, Peter D.

    1988-12-01

    The infinite dimensional phase space of the Vlasov equation is foliated by symplectic manifolds (leaves) which are invariant under the dynamics. By adopting a Lie transform representation, exp{ W, }, for near-identity canonical transformations we obtain a local coordinate system on a leaf. The evolution equation defined by restricting the Vlasov equation to the leaf is approximately represented by the evolution of W. We derive the equation for ? tW and show that it is hamiltonian relative to the nondegenerate Kirillov-Kostant-Souriau symplectic structure.

  16. Biospeckle assessment of torn plant leaf tissue and automated computation of leaf vein density (LVD)

    NASA Astrophysics Data System (ADS)

    Zaheer Ansari, Mohammad; Nirala, Anil Kumar

    2015-05-01

    In this work we propose an alternative measure of biospeckle activity in biological leaf tissues. The activity images obtained using the proposed method i.e., weighted parameterized Fujii method show relatively higher contrast compared to the existing methods. Leave veins which were not visible using the existing methods are clearly visible using the proposed method. In addition, we have also measured leaf vein density (LVD) within a leaf tissue using biospeckle technique for the first time, to the best of our knowledge. Algorithm for computing LVD from activity images generated by the proposed method is described to facilitate ease in adopting this method.

  17. Leaf Abscisic Acid Accumulation in Response To Substrate Water Content: Linking Leaf Gas Exchange Regulation with Leaf Abscisic Acid Concentration

    Microsoft Academic Search

    William L. Bauerle; William W. Inman; Jerry B. Dudley

    2006-01-01

    ADDITIONAL INDEX WORDS. stomatal conductance, drought tolerance, genotype variation ABSTRACT. Quantitative differences in leaf abscisic acid (ABAL) among four cultivars of red maple (Acer rubrum L.) and one freeman maple (Acer ×freemanii E. Murray) cultivar were investigated. This study tested the hypothesis that ABAL concentration can be used to compare the effects of water stress on the gas exchange response

  18. Mycosphaerella species causing leaf disease in South African Eucalyptus plantations

    E-print Network

    by modern phylogenetic approaches. Species of Mycosphaerella include both saprophytes and parasitesMycosphaerella species causing leaf disease in South African Eucalyptus plantations Gavin C. HUNTER species of Mycosphaerella are associated with a destructive Eucalyptus leaf disease known

  19. Molecular Models of Leaf Extracts

    NSDL National Science Digital Library

    Our Featured Molecules this month come from the paper by Pelter et. al. on the analysis of leaf extracts by thin-layer chromatography (1). As the authors discuss, their experiment may be used in courses at various levels of the curriculum. The molecules discussed in the paper are also of wide interest both for their structural properties and their wide-ranging appearance in both natural and synthetic substances. Included in the molecule collection are all of the isomers for the molecules pictured in the text with the exception of menthyl acetate, for which only one structure is given (see below). All of these molecules have been optimized at the HF/631-G(d) level. The menthol family enantiomeric pairs of menthol, isomenthol, neomenthol and neoisomenthol provide a rich yet coherent group of molecules on which to base discussion of chirality, enantiomers and diastereomers. Treadwell and Black have described some of the differences in physical properties of four members of this family, and several other experiments using one or more menthols have been published in this Journal (2, 3). I have created a Web page in which the eight molecules are embedded in no particular order, and with no rational file names. This is being used in at least one of our organic sections to give students experience at identifying enantiomers, and diastereomers, and in applying R/S notation (4). As access to computational software becomes more common, and as efforts are being made to incorporate more relevant modeling experiments into all levels of the curriculum, the menthols again present some interesting possibilities. While students at the organic level know about enantiomers differing in their optical rotation, and about chiral molecules interacting with chiral and achiral environments, it is instructive for them to think of other ways in which enantiomers and diastereomers are the same or different. Three useful ways of checking to see whether two structures are truly enantiomers is to compute their total energies, vibrational spectra, and dipole moments. These calculations are available in most common computational packages. Figure 1 shows the results of energy calculations on optimized structures of the eight isomers. The enantiomeric pairs have, as expected, exactly the same total energy, while the various diastereomers differ in energy. The computation of the vibrational spectra is a very sensitive probe to determine whether two structures are optimized and enantiomeric or not. Structures that are almost enantiomeric, but not quite optimized, may exhibit similar energies, but the low frequency vibrations will be sensitive to any deviation from optimization. If two supposedly enantiomeric structures do not have the same computed vibrations, or if either shows a negative frequency, the structures need to be optimized more carefully. As with the vibrational frequencies, enantiomers should show identical dipole moments. Only one structure of the eight isomers in the menthyl acetate family is included in the collection, giving students the chance to build the other seven and verify their computed properties. Because of the central role that chirality plays in chemistry, and particularly in biochemistry, it seems appropriate to introduce some of these visualization and modeling exercises early in the curriculum, and in courses designed for students majoring in other areas. Students in various courses could pursue other aspects of these same molecules including odor and cooling properties, and green chemistry approaches to synthesizing menthols.

  20. Calculations of the transpiration rate and temperature of a leaf

    Microsoft Academic Search

    E. T. Linacre

    1964-01-01

    Sample calculations of the water-loss rate and the temperature of a leaf have been made in terms of three climatic factors (i. e. net radiation intensity, ambient temperature and ambient vapour pressure) and two diffusion resistances, respectively within and outside the leaf tissue. The results indicate the variability of the ratio of the respective water losses from a leaf and

  1. Pecan leaf analysis: I. Varietal, fertilizer, and seasonal effects

    Microsoft Academic Search

    R. E. Worley

    1977-01-01

    Differences in elemental content of pecan [Carya illinoensis (Wang.) K. Koch] leaves among cultivars were found for N, P, K, Ca, Mg, Mn and Zn. Of the 7 elements studied, only leaf K indicated a date by cultivar interaction. Differences in leaf K among cultivars became greater as the season progressed. Increasing rate of application of N?P?K fertilizer increased leaf

  2. Leaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought

    E-print Network

    Sack, Lawren

    simulations of the leaf hydraulic system showed that a reduction of hydraulic conductance of the mesophyll through the hydraulic system. The leaf hydraulic system has two components, which act essentiallyLeaf Shrinkage with Dehydration: Coordination with Hydraulic Vulnerability and Drought Tolerance1[C

  3. Mapping vineyard leaf area with multispectral satellite imagery

    Microsoft Academic Search

    L. F. Johnson; D. E. Roczen; S. K. Youkhana; R. R. Nemani; D. F. Bosch

    2003-01-01

    Vineyard leaf area is a key determinant of grape characteristics and wine quality. As is frequently the case in agriculture, available ground-based leaf area measurements employed by growers are not well suited to larger area mapping. In this study, IKONOS high spatial resolution, multispectral satellite imagery was used to map leaf area throughout two commercial wine grape vineyards (approximately 800

  4. Fossil evidence for Cretaceous escalation in angiosperm leaf vein evolution

    E-print Network

    Bermingham, Eldredge

    Fossil evidence for Cretaceous escalation in angiosperm leaf vein evolution Taylor S. Feilda,1 plants that dominate modern vegetation possess leaf gas exchange potentials that far exceed those of all. Using vein density (DV) measurements of fossil angiosperm leaves, we show that the leaf hydraulic

  5. 7 CFR 29.3153 - Leaf (B Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...percent injury tolerance. B3GF Good Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B4GF Fair Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B5GF Low Green-tan Leaf. Fleshy to medium...

  6. 7 CFR 29.3153 - Leaf (B Group).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...percent injury tolerance. B3GF Good Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B4GF Fair Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B5GF Low Green-tan Leaf. Fleshy to medium...

  7. TEMPORAL ANALYSIS OF LEAF GROWTH UNDER CLIMATE CHANGE SCENARIOS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many of the cellular and molecular mechanisms that control leaf growth and expansion have yet to be examined, even though this information would be valuable for predicting leaf area throughout growth and could potentially be used to maximize leaf area index, which could increase canopy productivity ...

  8. Interactive computer software development for leaf area measurement

    Microsoft Academic Search

    C. Igathinathane; V. S. S. Prakash; U. Padma; G. Ravi Babu; A. R. Womac

    2006-01-01

    A novel idea of utilizing only a computer to determine leaf area and perimeter was developed. The procedure is essentially computer software developed in Visual Basic that uses the computer monitor as the working surface to trace leaf outline and determines leaf area, perimeter, length, and width. Testing the software for effects of orientation, shape, and size of objects was

  9. Mandatory Leaf Node Prediction in Hierarchical Multilabel Classification

    E-print Network

    Kwok, James Tin-Yau

    Mandatory Leaf Node Prediction in Hierarchical Multilabel Classification Wei Bi James T. Kwok Department of Computer Science and Engineering Hong Kong University of Science and Technology Clear Water Bay be required to always end at leaf nodes. This is called mandatory leaf node prediction (MLNP) and is par

  10. Research Papers Leaf Processing by Wild Chimpanzees: Physically Defended Leaves

    E-print Network

    Research Papers Leaf Processing by Wild Chimpanzees: Physically Defended Leaves Reveal Complex Andrews, Fife, Scotland Abstract The manual processing of eight species of leaf was investigated in the M-group chimpanzees of Mahale Mountains National Park, Tanzania. Leaf species varied in the extent to which physical

  11. The auxin influx carrier is essential for correct leaf positioning

    E-print Network

    Kuhlemeier, Cris

    The auxin influx carrier is essential for correct leaf positioning Pia A. Stieger, Didier Reinhardt inhibitor N-1-naphthylphtha- lamic acid (NPA) causes a complete cessation of leaf initiation, a defect and outgrowth of leaf primordia at the shoot apical meristem of tomato. By using a combination of transport

  12. ORIGINAL PAPER Factors controlling plasticity of leaf morphology

    E-print Network

    Boyer, Edmond

    ORIGINAL PAPER Factors controlling plasticity of leaf morphology in Robinia pseudoacacia L. II: the impact of water stress on leaf morphology of seedlings grown in a controlled environment chamber Yanxiang designed an experiment to analyze the effect of long-term water stress on leaf growth of Robinia seedlings

  13. 7 CFR 51.1220 - Leaf or limb rub injury.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Agriculture 2 2013-01-01 2013-01-01 false Leaf or limb rub injury. 51.1220 Section 51.1220...for Grades of Peaches Definitions § 51.1220 Leaf or limb rub injury. “Leaf or limb rub injury” means that the scarring...

  14. Oak Leaf Blister Theresa Badurek, Urban Horticulture Extension Agent

    E-print Network

    Jawitz, James W.

    Oak Leaf Blister Theresa Badurek, Urban Horticulture Extension Agent It's that time of year again spring! Wait a minute oak leaves blistering? Yes, this is a common sight in the spring. Oak leaf blister (Taphrina caerulescens) is a common fungal leaf disease on oaks in Florida. It can affect any

  15. Manual of Leaf Architecture Morphological description and categorization

    E-print Network

    Wilf, Peter

    - 1 - Manual of Leaf Architecture Morphological description and categorization of dicotyledonous reserved. Published and distributed by: Leaf Architecture Working Group c/o Scott Wing Department-9677554-0-9 Please cite as: Manual of Leaf Architecture - morphological description and categorization

  16. 9 CFR 319.702 - Lard, leaf lard.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Lard, leaf lard. 319.702 Section 319.702...Oils, Shortenings § 319.702 Lard, leaf lard. (a) Lard is the fat rendered...brains, or settlings and skimmings. “Leaf Lard” is lard prepared from fresh...

  17. Better Algorithms and Bounds for Directed Maximum Leaf Problems

    E-print Network

    Krivelevich, Michael

    Better Algorithms and Bounds for Directed Maximum Leaf Problems Noga Alon 1 , Fedor V. Fomin 2 of Mathematical Sciences Chennai, 600 017, India saket@imsc.res.in Abstract. The Directed Maximum Leaf Out Maximum Leaf Out­Branching problem is to find an out­branching in a given digraph with the maximum number

  18. 7 CFR 51.1220 - Leaf or limb rub injury.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Agriculture 2 2014-01-01 2014-01-01 false Leaf or limb rub injury. 51.1220 Section 51.1220...for Grades of Peaches Definitions § 51.1220 Leaf or limb rub injury. “Leaf or limb rub injury” means that the scarring...

  19. Logspace and Logtime Leaf Languages \\Lambda Birgit Jenner y

    E-print Network

    McKenzie, Pierre

    Logspace and Logtime Leaf Languages \\Lambda Birgit Jenner y Universit¨at T¨ubingen Pierre Mc with input x gives rise to a leaf string formed by concatenating the outcomes of all the com­ putations in the tree in lexicographical order. We may characterize prob­ lems by considering, for a particular ``leaf

  20. 7 CFR 51.1220 - Leaf or limb rub injury.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Agriculture 2 2012-01-01 2012-01-01 false Leaf or limb rub injury. 51.1220 Section 51.1220...for Grades of Peaches Definitions § 51.1220 Leaf or limb rub injury. “Leaf or limb rub injury” means that the scarring...