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Sample records for spinach leaf sucrose-phosphate

  1. Kinetic Characterization of Spinach Leaf Sucrose-Phosphate Synthase 1

    PubMed Central

    Amir, Jacob; Preiss, Jack

    1982-01-01

    The spinach (Spinacia oleracea) leaf sucrose-phosphate synthase was partially purified via DEAE-cellulose chromatography, and its kinetic properties were studied. Fructose-6-phosphate saturation curves were sigmoidal, while UDPglucose saturation curves were hyperbolic. At subsaturating concentrations of fructose-6-phosphate, 1,5 anhydroglucitol-6-phosphate had a stimulatory effect on enzyme activity, suggesting multiple and interacting fructose-6-phosphate sites on sucrose-phosphate synthase. The concentrations required for 50% of maximal activity were 3.0 millimolar and 1.3 millimolar, respectively, for fructose-6-phosphate and UDPglucose. The enzyme was not stimulated by divalent cations. Inorganic phosphate proved to be a potent inhibitor, particularly at low concentrations of substrate. Phosphate inhibition was competitive with UDPglucose, and its Ki was determined to be 1.75 millimolar. Sucrose phosphate, the product of the reaction, was also shown to be a competitive inhibitor towards UDPglucose concentration and had Ki of 0.4 millimolar. The kinetic results suggest that spinach leaf sucrose-phospahte synthase is a regulatory enzyme and that its activity is modulated by the concentrations of phosphate, fructose-6-phosphate, and UDPglucose occurring in the cytoplasm of the leaf cell. PMID:16662338

  2. Multisite phosphorylation of spinach leaf sucrose-phosphate synthase

    SciTech Connect

    Huber, J.L.; Huber, S.C. )

    1990-05-01

    Spinach leaf sucrose-phosphate synthase is phosphorylated both in vivo and in vitro on serine residues. Phosphorylation of SPS in vivo yields twelve major phosphopeptides after a tryptic digest and two dimensional mapping. The in vivo labeling of three of these SPS P-peptides is reduced in illuminated leaves where the extracted enzyme is activated relative to that of dark leaves. Two of these inhibitory sites are phosphorylated as well when SPS is inactivated in vitro using ({sup 32}P)ATP. In vivo phosphorylation of two other sites is enhanced during mannose feeding of the leaves (in light or dark) which produces the highest activation state of SPS. Overall, the results confirm that light-dark regulation of SPS activity occurs as a result of regulatory seryl-phosphorylation and involves a balance between phosphorylation of sites which inhibit or stimulate activity. Regulation of the SPS protein kinase that inhibits activity is relatively unaffected by phosphate but inhibited by G1c 6-P (IC{sub 50}{approx}5 mM), which may explain the control of SPS activation state by light-dark signals.

  3. Inactivation of highly activated spinach leaf sucrose-phosphate synthase by dephosphorylation. [Spinacia oleracea

    SciTech Connect

    Huber, J.L. ); Huber, S.C. North Carolina State Univ., Raleigh ); Hite, D.R.C.; Outlaw, W.H. Jr. )

    1991-01-01

    Spinach (Spinacia oleracea L.) leaf sucrose-phosphate synthase (SPS) can be phosphorylated and inactivated in vitro with ({gamma}-{sup 32}P)ATP. Thus, it was surprising to find that SPS, extracted from leaves fed mannose in the light to highly activate the enzyme, could be inactivated in an ATP-independent manner when desalted crude extracts were preincubated at 25{degrees}C before assay. The spontaneous inactivation involved a loss in activity measured with limiting substrate concentrations in the presence of the inhibitor, Pi, without affecting maximum catalytic activity. The spontaneous inactivation was unaffected by exogenous carrier proteins and protease inhibitors, but was inhibited by inorganic phosphate, fluoride, and molybdate, suggesting that a phosphatase may be involved. Okadaic acid, a potent inhibitor of mammalian type 1 and 2A protein phosphatases, had no effect up to 5 micromolar. Inactivation was stimulated about twofold by exogenous Mg{sup 2+} and was relatively insensitive to Ca{sup 2+} and to pH over the range pH 6.5 to 8.5. Radioactive phosphate incorporated into SPS during labeling of excised leaves with ({sup 32}P)Pi (initially in the dark and then in the light with mannose) was lost with time when desalted crude extracts were incubated at 25 C, and the loss in radiolabel was substantially reduced by fluoride. These results provide direct evidence for action of an endogenous phosphatase(s) using SPS as substrate.

  4. Protein phosphorylation as a mechanism for regulation of spinach leaf sucrose-phosphate synthase activity

    SciTech Connect

    Huber, J.L.A.; Huber, S.C. )

    1989-04-01

    Protein phosphorylation has been identified as a mechanism for the light-dark regulation of spinach sucrose-phosphate synthase (SPS) activity, previously shown to involve some type of covalent modification of the enzyme. The 120 kD subunit of SPS in extracts of light-treated leaves was labeled with {sup 32}P in the presence of ({gamma}-{sup 32}P) ATP. In this in vitro system, {sup 32}P incorporation into light-activated SPS was dependent upon ATP and magnesium concentrations as well as time, and was closely paralleled by inactivation of the enzyme. The soluble protein kinase involved in the interconversion of SPS between activated and deactivated forms may be specific for SPS as it co-purifies with SPS during partial purification of the enzyme. The kinase appears not to be calcium activated and no evidence has been obtained for metabolite control of SPS phosphorylation/inactivation.

  5. 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.

  6. 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.

  7. Effect of N-Source on Soybean Leaf Sucrose Phosphate Synthase, Starch Formation, and Whole Plant Growth 1

    PubMed Central

    Kerr, Phillip S.; Huber, Steven C.; Israel, Daniel W.

    1984-01-01

    Soybeans (Glycine max L. Merr. cv Tracy and Ransom) were grown under N2-dependent or NO3?-supplied conditions, and the partitioning of photosynthate and dry matter was characterized. Although no treatment effects on photosynthetic rates were observed, NO3?-supplied plants in both cultivars had lower starch accumulation rates than N2-dependent plants. Leaf extracts of NO3?-supplied plants had higher activities of sucrose phosphate synthase (SPS) and cytoplasmic fructose-1,6-bisphosphatase (FBPase) than N2-dependent plants. The variation in starch accumulation was correlated negatively with the activity of SPS, but not the activity of FBPase, UDP-glucose pyrophosphorylase, or ADP-glucose pyrophosphorylase. These results suggested that starch accumulation is biochemically controlled, in part, by the activity of SPS. Leaf starch content at the beginning of the photoperiod was lower in NO3?-supplied plants than N2-dependent plants in both cultivars which suggested that net starch utilization as well as accumulation was affected by N source. Total dry matter accumulation and dry matter distribution was affected by N source in both cultivars, but the cultivars differed in how dry matter was partitioned between the shoot and root as well as within the shoot. The activity of SPS was correlated positively with total dry matter accumulation which suggested that SPS activity is related to plant growth rate. The results suggested that photosynthate partitioning is an important but not an exclusive factor which determines whole plant dry matter distribution. PMID:16663648

  8. Antihypertensive properties of spinach leaf protein digests.

    PubMed

    Yang, Yanjun; Marczak, Ewa D; Usui, Hachiro; Kawamura, Yukio; Yoshikawa, Masaaki

    2004-04-21

    Leaf protein containing approximately 50% rubisco (ribulose bisphosphate carboxylase/oxygenase) was obtained from fresh spinach leaf with the use of a simple extraction method. Pepsin and pepsin-pancreatin digests of spinach leaf protein have potent angiotensin-I converting enzyme inhibitory properties with IC(50) values of 56 and 120 microg/mL, respectively. Both digests of leaf protein have antihypertensive effects after oral administration to spontaneously hypertensive rats (SHR) with minimum effective doses of 0.25 and 0.5 g/kg, respectively. The maximum antihypertensive effect for the pepsin digest was observed 4 h after oral administration, while for the pepsin-pancreatin digest, the maximum effect was observed 2 h after oral administration. Undigested spinach leaf protein did not exert any significant antihypertensive effect after oral administration to SHR at doses of 0.5 and 1 g/kg. Obtained results show that the pepsin digest of leaf protein may be useful in treatment of hypertension. PMID:15080624

  9. Interaction between Silver Nanoparticles and Spinach Leaf

    NASA Astrophysics Data System (ADS)

    Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

    2013-12-01

    Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. CytoViva Hyperspectral Imaging System was also employed to map the distribution of nanoAg in the leaf profile. Significant sorption of nanoAg on spinach leaf should urge the precaution with potential widespread use of ENPs in agriculture.

  10. Phosphoenolpyruvate Carboxylase from Spinach Leaf Tissue

    PubMed Central

    Mukerji, S. K.; Yang, S. F.

    1974-01-01

    Phosphoenolpyruvate carboxylase (EC 4.1.1.31), partially purified from spinach (Spinacia oleracea) leaves, is inhibited by SO32? ion. The inhibition is competitive or mixed type with respect to HCO3? (Ki = 17 mm), and noncompetitive with respect to phosphoenolpyruvic acid (Ki = 11 mm), Mg2+ (Ki = 10 mm), and Mn2+ (Ki = 2.4 mm). The inhibitory effect of SO32? is more significant in the presence of Mn2+ than in the presence of Mg2+. l-Malate, an inhibitor of phosphoenolpyruvate carboxylase activity, and SO32? may bind at the same site on the enzyme. Glyoxal bisulfite and glyoxylate bisulfite are equally effective inhibitors of the enzyme activity as SO32?, but ?-hydroxypyridinemethanesulfonate is a weak inhibitor. The data are discussed in relation to the physiological effect of the air pollutant (SO2) on plant leaf metabolism. PMID:16658799

  11. 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....

  12. Purification and Properties of Spinach Leaf Debranching Enzyme 1

    PubMed Central

    Ludwig, Isabella; Ziegler, Paul; Beck, Erwin

    1984-01-01

    Starch debranching enzyme was purified from intact spinach (Spinacia oleracea L. cv Vital) chloroplasts and from a spinach leaf extract using affinity chromatography on Sepharose 6B-bound cycloheptaamylose (Schardinger β-dextrin). The enzyme from both sources was homogeneous upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Spinach leaf debranching enzyme appears to consist of a single polypeptide chain, since the molecular weight of the native protein (110,000 daltons) was not changed by treatment with sodium dodecyl sulfate. Only one spinach leaf debranching enzyme band could be detected after electrophoresis of a leaf extract on amylopectin-containing polyacrylamide gel, the retardation factor of which coincided with that of the single band seen with the chloroplast enzyme. The purified enzyme exhibited strong pullulanase activity, the specific activity being 69 units per milligram protein with pullulan and 22 units per milligram protein with amylopectin. Cycloheptaamylose is a potent competitive inhibitor of spinach leaf debranching enzyme. The pH optimum of the enzyme was found to be 5.5. The purified enzyme is rather unstable at both 20° and 0°C. Part of the activity lost under storage or at a suboptimal pH could immediately be restored by the addition of thiols. The reactivatable protein, being of the same molecular weight as the native enzyme, exhibited a somewhat altered electrophoretic mobility resulting in one or two minor bands on a zymogram. Images Fig. 2 Fig. 3 PMID:16663522

  13. Freezing Tolerance of Citrus, Spinach, and Petunia Leaf Tissue 1

    PubMed Central

    Yelenosky, George; Guy, Charles L.

    1989-01-01

    Seasonal variations in freezing tolerance, water content, water and osmotic potential, and levels of soluble sugars of leaves of field-grown Valencia orange (Citrus sinensis) trees were studied to determine the ability of citrus trees to cold acclimate under natural conditions. Controlled environmental studies of young potted citrus trees, spinach (Spinacia pleracea), and petunia (Petunia hybrids) were carried out to study the water relations during cold acclimation under less variable conditions. During the coolest weeks of the winter, leaf water content and osmotic potential of field-grown trees decreased about 20 to 25%, while soluble sugars increased by 100%. At the same time, freezing tolerance increased from lethal temperature for 50% (LT50) of ?2.8 to ?3.8C. In contrast, citrus leaves cold acclimated at a constant 10C in growth chambers were freezing tolerant to about ?6C. The calculated freezing induced cellular dehydration at the LT50 remained relatively constant for field-grown leaves throughout the year, but increased for leaves of plants cold acclimated at 10C in a controlled environment. Spinach leaves cold acclimated at 5C tolerated increased cellular dehydration compared to nonacclimated leaves. Cold acclimated petunia leaves increased in freezing tolerance by decreasing osmotic potential, but had no capacity to change cellular dehydration sensitivity. The result suggest that two cold acclimation mechanisms are involved in both citrus and spinach leaves and only one in petunia leaves. The common mechanism in all three species tested was a minor increase in tolerance (about ?1C) resulting from low temperature induced osmotic adjustment, and the second in citrus and spinach was a noncolligative mechanism that increased the cellular resistance to freeze hydration. PMID:16666563

  14. 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.

  15. EFFECT OF LIGHT INTENSITY, SOIL TYPE, AND LITHIUM ADDITION ON SPINACH AND MUSTARD GREENS LEAF CONSTITUENTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A greenhouse experiment was conducted near Weslaco, Texas (Lat. 26o 8' N, Long. 97o 57' W) between 14 Dec. 2005 and 17 Feb 2006 to evaluate the effect of soil type, light environment, and lithium addition on the leaf nutrients of spinach and mustard greens. Cultivars Samish (Spinacia oleracea) and...

  16. Abscisic Acid accumulation in spinach leaf slices in the presence of penetrating and nonpenetrating solutes.

    PubMed

    Creelman, R A; Zeevaart, J A

    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). About equal amounts of ABA were found both in the leaf slices and in detached leaves, whereas 2 to 4 times more ABA accumulated in the medium than in the slices. 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. Ethylene glycol was not inhibitory with respect to ABA accumulation. 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. Aquacide III causes cytorrhysis, a situation similar to that found in wilted leaves. Thus, it appears that loss of turgor is essential for ABA accumulation.When spinach leaf slices were incubated with solutes which are supposed to disturb membrane integrity (KHSO(3), 2-propanol, or KCl) no increase in ABA was observed. These data indicate that, with respect to the accumulation of ABA, mannitol caused a physical stress (loss of turgor) rather than a chemical stress (membrane damage). PMID:16664022

  17. 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 Central

    Volkert, Kathrin; Debast, Stefan; Voll, Lars M.; Voll, Hildegard; Schiel, Ingrid; Hofmann, Jrg; Schneider, Sabine; Brnke, Frederik

    2014-01-01

    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. Promoterreporter gene analyses and quantitative real-time reverse transcriptionPCR 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

  18. Pathways of Fatty Acid hydroperoxide metabolism in spinach leaf chloroplasts.

    PubMed

    Vick, B A; Zimmerman, D C

    1987-12-01

    The metabolism of 13-hydroperoxylinolenic acid was examined in protoplasts and homogenates prepared from mature leaves of spinach (Spinacia oleracea L.). Chloroplast membranes were the principal site for metabolism of the compound by at least two highly hydrophobic enzyme systems, hydroperoxide lyase and hydroperoxide dehydrase, the new name for an enzyme system formerly known as hydroperoxide isomerase and hydroperoxide cyclase. Hydroperoxide lyase was most active above pH 7 and could be separated from hydroperoxide dehydrase by anion exchange chromatography. Hydroperoxide dehydrase, measured by the formation of both alpha-ketol product and 12-oxo-phytodienoic acid, had its optimum activity in the range of pH 5 to 7. Lyase was more active than dehydrase activity when the enzymes were extracted by homogenization. The reverse was true when the enzyme activities were measured in protoplasts, which are isolated by gentle extraction methods. The variation in enzyme activity ratios with extraction methods suggests that hydroperoxide lyase is activated by plant injury and thus may function in a wound response. In the absence of injury, the normal pathway of fatty acid hydroperoxide metabolism is probably by hydroperoxide dehydrase activity. The molecular weights of both the lyase and dehydrase were approximately 220,000, as estimated by gel filtration. PMID:16665806

  19. Effect of bicarbonate and oxaloacetate on malate oxidation by spinach leaf mitochondria.

    PubMed

    Neuburger, M; Douce, R

    1980-02-01

    Mitochondria isolated from spinach leaves oxidized malate by both a NAD+-linked malic enzyme and malate dehydrogenase. In the presence of sodium arsenite the accumuation of oxaloacetate and pyruvate during malate oxidation was strongly dependent on the malate concentration, the pH in the reaction medium and the metabolic state condition. Bicarbonate, especially at alkaline pH, inhibited the decarboxylation of malate by the NAD+-linked malic enzyme in vitro and in vivo. Analysis of the reaction products showed that with 15 mM bicarbonate, spinach leaf mitochondria excreted almost exclusively oxaloacetate. The inhibition by oxaloacetate of malate oxidation by spinach leaf mitochondria was strongly dependent on malate concentration, the pH in the reaction medium and on the metabolic state condition. The data were interpreted as indicating that: (a) the concentration of oxaloacetate on both sides of the inner mitochondrial membrane governed the efflux and influx of oxaloacetate; (b) the NAD+/NADH ratio played an important role in regulating malate oxidation in plant mitochondria; (c) both enzymes (malate dehydrogenase and NAD+-linked malic enzyme) were competing at the level of the pyridine nucleotide pool, and (d) the NAD+-linked malic enzyme provided NADH for the reversal of the reaction catalyzed by the malate dehydrogenase. PMID:7356982

  20. 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

  1. 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

  2. Malate and Dihydroxyacetone Phosphate-dependent Nitrate Reduction in Spinach Leaf Protoplasts 1

    PubMed Central

    Rathnam, C. K. M.

    1978-01-01

    Isolated spinach (Spinacia oleracea L. var. Bloomsdale) leaf protoplasts reduced nitrate at rates of 9 micromoles per milligram chlorophyll per hour in light with a 3- to 4-fold stimulation in the presence of HCO3?. A similar stimulation of nitrate reduction in the absence of CO2 fixation was obtained by the addition of malate, oxaloacetate (OAA), phospho-3-glyceric acid (PGA), or dihydroxyacetone phosphate (DHAP). Stimulation by malate and DHAP was light-independent, while the PGA and OAA effect was light-dependent. Nitrate reduction was found to be coupled to the cytoplasmic oxidation of DHAP or malate. The PGA/DHAP and OAA/malate shuttle across the chloroplast envelope has been demonstrated to support CO2 fixation and/or nitrate reduction. The leaf protoplasts readily assimilated nitrate into amino-N in a stoichiometric relationship. PMID:16660489

  3. The Path of Carbon in Photosynthesis XIX. The Identification of Sucrose Phosphate in Sugar Beet Leaves

    DOE R&D Accomplishments Database

    Buchanan, J. G.

    1952-09-01

    The recognition and characterization of a sucrose phosphate as an intermediate in sucrose by synthesis by green plants is described. A tentative structure for this phosphate is proposed and its mode of formation suggested.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  5. Photosynthesis-related infrared light transmission changes in spinach leaf segments

    SciTech Connect

    Akimoto, T.

    1985-10-01

    The time courses of infrared light transmission changes and fluorescence induced by light in spinach leaf segments were measured. The illumination by red light exhibited a complex wave pattern. The transmission approached the baseline after repeating decreases and increases. Illumination by far-red light decreased the transmission. One of the differences between the two responses was the difference between the two amplitudes of the first increasing component. The component in the red light response was larger than the component in the far-red light response. The transmission decrease by far-red light is supposed to correspond to ''red drop.'' The transmission decrease by far-red light was suppressed by red light. This is due to an activation of a transmission-increasing component. This probably corresponds to ''enhancement.'' A proportional correlation existed between the intensity of far-red light and the minimum intensity of red light that suppressed the transmission decrease induced by far-red light. The component which made Peak D in the time course of fluorescence yield and the first increasing component in the transmission changes were suppressed by intense light.

  6. Expression, purification and preliminary crystallographic analysis of sucrose phosphate synthase (SPS) from Halothermothrix orenii

    SciTech Connect

    Huynh, Frederick; Tan, Tien-Chye; Swaminathan, Kunchithapadam; Patel, Bharat K. C.

    2005-01-01

    The first crystallographic study of a sucrose phosphate synthase from H. orenii, an organism that is both thermophilic and halophilic, is reported. The protein crystal diffracts X-rays to 3.01 . This is the first report of the crystallization of a sucrose phosphate synthase (SPS; EC 2.4.1.14). It also constitutes the first study of a sucrose phosphate synthase from a non-photosynthetic thermohalophilic anaerobic bacterium, Halothermothrix orenii. The purified recombinant spsA protein has been crystallized in the monoclinic space group C2, with unit-cell parameters a = 154.2, b = 47.9, c = 72.3 , ? = 103.16, using the hanging-drop vapour-diffusion method. The crystal diffracts X-rays to a resolution limit of 3.01 . Heavy-metal and halide-soaking trials are currently in progress to solve the structure.

  7. 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; Yu, Xiyan; Wang, Xiufeng

    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.

  8. Spinach leaf chloroplast CO sub 2 and NO sub 2 sup minus photoassimilations do not compete for photogenerated reductant

    SciTech Connect

    Robinson, J.M. )

    1988-12-01

    Potential competition between CO{sub 2} and NO{sub 2}{sup {minus}} photoassimilation for photogenerated reductant (e.g. reduced ferredoxin and NADPH) was examined employing isolates of mesophyll cells and intact chloroplasts derived from mature source spinach leaves. Variations in the magnitude of incident light energy were used to manipulate the supply of reductant in situ within chloroplasts. Leaf cell and plastid isolates were fed with saturating CO{sub 2} and/or NO{sub 2}{sup {minus}} to produce the highest demand for reductant by CO{sub 2} and/or NO{sub 2}{sup {minus}} assimilatory processes (enzymes). Even in the presence of CO{sub 2} fixation, NO{sub 2}{sup {minus}} reduction in intact leaf cell isolates as well as plastid isolates was maximal at light energies as low as 50 to 200 microeinsteins per second per square meter. Simultaneously, 500 to 800 microeinsteins per second per square meter were required to support maximal CO{sub 2} assimilation. Regardless of the magnitude of the incident light energy, CO{sub 2} assimilation did not repress NO{sub 2}{sup {minus}} reduction, nor were these two processes mutually repressed. These observations have been interpreted to mean that reduced ferredoxin levels in situ in the plastids of mature source leaf mesophyll cells were adequate to supply the concurrent maximal demands exerted by enzymes associated with CO{sub 2} as well as with inorganic nitrogen photoassimilation.

  9. Light/Dark Profiles of Sucrose Phosphate Synthase, Sucrose Synthase, and Acid Invertase in Leaves of Sugar Beets

    PubMed Central

    Vassey, Terry L.

    1989-01-01

    The activity of sucrose phosphate synthase, sucrose synthase, and acid invertase was monitored in 1- to 2-month-old sugar beet (Beta vulgaris L.) leaves. Sugar beet leaves achieve full laminar length in 13 days. Therefore, leaves were harvested at 2-day intervals for 15 days. Sucrose phosphate synthase activity was not detectable for 6 days in the dark-grown leaves. Once activity was measurable, sucrose phosphate synthase activity never exceeded half that observed in the light-grown leaves. After 8 days in the dark, leaves which were illuminated for 30 minutes showed no significant change in sucrose phosphate synthase activity. Leaves illuminated for 24 hours after 8 days in darkness, however, recovered sucrose phosphate synthase activity to 80% of that of normally grown leaves. Sucrose synthase and acid invertase activity in the light-grown leaves both increased for the first 7 days and then decreased as the leaves matured. In contrast, the activity of sucrose synthase oscillated throughout the growth period in the dark-grown leaves. Acid invertase activity in the dark-grown leaves seemed to be the same as the activity found in the light-grown leaves. PMID:16666537

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

    PubMed

    Niemira, Brendan A; Cooke, Peter H

    2010-06-01

    Escherichia coli O157:H7 contamination of leafy green vegetables is an ongoing concern for consumers. Biofilm-associated pathogens are relatively resistant to chemical treatments, but little is known about their response to irradiation. Leaves of Romaine lettuce and baby spinach were dip inoculated with E. coli O157:H7 and stored at 4 degrees C for various times (0, 24, 48, 72 h) to allow biofilms to form. After each time, leaves were treated with either a 3-min wash with a sodium hypochlorite solution (0, 300, or 600 ppm) or increasing doses of irradiation (0, 0.25, 0.5, 0.75, or 1 kGy). Viable bacteria were recovered and enumerated. Chlorine washes were generally only moderately effective, and resulted in maximal reductions of 1.3 log CFU/g for baby spinach and 1.8 log CFU/g for Romaine. Increasing time in storage prior to chemical treatment had no effect on spinach, and had an inconsistent effect on 600 ppm applied to Romaine. Allowing time for formation of biofilm-like aggregations reduced the efficacy of irradiation. D(10) values (the dose required for a 1 log reduction) significantly increased with increasing storage time, up to 48 h postinoculation. From 0 h of storage, D(10) increased from 0.19 kGy to a maximum of 0.40 to 0.43 kGy for Romaine and 0.52 to 0.54 kGy for spinach. SEM showed developing biofilms on both types of leaves during storage. Bacterial colonization of the stomata was extensive on spinach, but not on Romaine. These results indicate that the protection of bacteria on the leaf surface by biofilm formation and stomatal colonization can reduce the antimicrobial efficacy of irradiation on leafy green vegetables. PMID:20629883

  11. Summer (subarctic) versus winter (subtropic) production affects spinach (Spinacia oleracea L.) leaf bionutrients: vitamins (C, E, Folate, K1, provitamin A), lutein, phenolics, and antioxidants.

    PubMed

    Lester, Gene E; Makus, Donald J; Hodges, D Mark; Jifon, John L

    2013-07-24

    Comparison of spinach (Spinacia oleracea L.) cultivars Lazio and Samish grown during the summer solstice in the subarctic versus the winter solstice in the subtropics provided insight into interactions between production environment (light intensity), cultivar, and leaf age/maturity/position affecting bionutrient concentrations of vitamins (C, E, folate, K1, provitamin A), lutein, phenolics, and antioxidants. Growing spinach during the winter solstice in the subtropics resulted in increased leaf dry matter %, oxidized (dehydro) ascorbic acid (AsA), ?- and ?-tocopherol, and total phenols but lower reduced (free) AsA, ?-carotene, folate, and antioxidant capacity compared to summer solstice-grown spinach in the subarctic. Both cultivars had similar bionutrients, except for higher dehydroAsA, and lower ?- and ?-tocopherol in 'Samish' compared to 'Lazio'. For most bionutrients measured, there was a linear, and sometimes quadratic, increase in concentrations from bottom to top canopy leaves. However, total phenolics and antioxidant capacity increased basipetally. The current study has thus demonstrated that dehydroAsA, ?-tocopherol, and ?-tocopherol were substantially lower in subarctic compared to subtropical-grown spinach, whereas the opposite relationship was found for antioxidant capacity, ?-carotene, and folates (vitamin B9). The observations are consistent with previously reported isolated effects of growth environment on bionutrient status of crops. The current results clearly highlight the effect of production environment (predominantly radiation capture), interacting with genetics and plant phenology to alter the bionutrient status of crops. While reflecting the effects of changing growing conditions, these results also indicate potential alterations in the nutritive value of foods with anticipated shifts in global climatic conditions. PMID:23834651

  12. Cloning and sequence analysis of sucrose phosphate synthase gene from varieties of Pennisetum species.

    PubMed

    Li, H C; Lu, H B; Yang, F Y; Liu, S J; Bai, C J; Zhang, Y W

    2015-01-01

    Sucrose phosphate synthase (SPS) is an enzyme used by higher plants for sucrose synthesis. In this study, three primer sets were designed on the basis of known SPS sequences from maize (GenBank: NM_001112224.1) and sugarcane (GenBank: JN584485.1), and five novel SPS genes were identified by RT-PCR from the genomes of Pennisetum spp (the hybrid P. americanum x P. purpureum, P. purpureum Schum., P. purpureum Schum. cv. Red, P. purpureum Schum. cv. Taiwan, and P. purpureum Schum. cv. Mott). The cloned sequences showed 99.9% identity and 80-88% similarity to the SPS sequences of other plants. The SPS gene of hybrid Pennisetum had one nucleotide and four amino acid polymorphisms compared to the other four germplasms, and cluster analysis was performed to assess genetic diversity in this species. Additional characterization of the SPS gene product can potentially allow Pennisetum to be exploited as a biofuel source. PMID:25867429

  13. Deep two-photon microscopic imaging through brain tissue using the second singlet state from fluorescent agent chlorophyll α in spinach leaf

    NASA Astrophysics Data System (ADS)

    Shi, Lingyan; Rodríguez-Contreras, Adrián; Budansky, Yury; Pu, Yang; An Nguyen, Thien; Alfano, Robert R.

    2014-06-01

    Two-photon (2P) excitation of the second singlet (S) state was studied to achieve deep optical microscopic imaging in brain tissue when both the excitation (800 nm) and emission (685 nm) wavelengths lie in the "tissue optical window" (650 to 950 nm). S2 state technique was used to investigate chlorophyll α (Chl α) fluorescence inside a spinach leaf under a thick layer of freshly sliced rat brain tissue in combination with 2P microscopic imaging. Strong emission at the peak wavelength of 685 nm under the 2P S state of Chl α enabled the imaging depth up to 450 μm through rat brain tissue.

  14. Relationship between Steady-State Fluorescence Yield and Photosynthetic Efficiency in Spinach Leaf Tissue 1

    PubMed Central

    Peterson, Richard B.; Sivak, Mirta N.; Walker, David A.

    1988-01-01

    The relationship between steady-state photosynthetic efficiency, as moles CO2 per mole of incident visible photons under 2% O2, and chlorophyll fluorescence quenching has been investigated in intact leaf tissue of Spinacia oleracia. Fluorescence yield was measured using a pulse amplitude modulation technique that permitted rapid and sensitive resolution and quantitation of photochemical and nonphotochemical quenching coefficients. A highly linear relationship was observed between photosynthetic efficiency and the ratio of photochemical:nonphotochemical quenching coefficients for values of the latter less than 1.6. This relationship applied whether irradiance or CO2 concentration was varied. The observed relationships between photochemical yield and fluorescence yield were compatible with the photosystem II model proposed by Butler and Kitajima (1975 Biochim Biophys Acta 376: 116-125). The results are discussed with respect to the proposed role of nonphotochemical quenching in regulating radiant energy utilization and also the applicability of fluorescence measurements as a means of estimation of the rate of photosynthetic electron transport. PMID:16666258

  15. Activation of SPS from darkened spinach leaves by an endogenous protein phosphatase

    SciTech Connect

    Huber, S.C.; Huber, J.L. )

    1990-05-01

    Sucrose-phosphate synthase from darkened spinach leaves has a low activation state but can undergo a time-dependent activation in desalted leaf extracts that is inhibited by Pi, molybdate, okadaic acid and vanadate, but stimulated by fluoride. SPS labeled in vivo with ({sup 32}P)Pi in excised leaves in the dark loses incorporated {sup 32}P with time when extracts are incubated at 25{degree}C. This loss is largely prevented by vanadate, suggesting that an endogenous protein phosphatase can use SPS as substrate. Changes in phosphorylation state are closely paralleled by changes in SPS activation state. The spontaneous activation achieved in the extracts can be reversed by addition of 2 mM MgATP. Feeding okadaic acid to darkened leaves prevents light activation of SPS suggesting that the endogenous protein phosphatase is similar to the type-1 enzyme of animal tissues. Overall, the results are consistent with the notion that light activation of SPS involves dephosphorylation of inhibitory phosphorylation site(s). Regulation of the protein phosphatase by Pi may be of physiological significance.

  16. 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.).

    PubMed

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

    2010-01-01

    Sucrose phosphate synthase (SPS) catalyzes the first step in the synthesis of sucrose in photosynthetic tissues. We characterized 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 showed nodule-enhanced expression, both MsSPSB genes exhibited leaf-enhanced expression. Alfalfa leaf and nodule SPS enzymes showed differences in chromatographic and electrophoretic migration and differences in V (max) and allosteric regulation. The root nodules in legume plants are a strong sink for photosynthates with its need for ATP, reducing power and carbon skeletons for dinitrogen fixation and ammonia assimilation. The expression of genes encoding SPS and other key enzymes in sucrose metabolism, sucrose phosphate phosphatase and sucrose synthase, was analyzed in the leaves and nodules of plants inoculated with Sinorhizobium meliloti. Based on the expression pattern of these genes, the properties of the SPS isoforms and the concentration of starch and soluble sugars in nodules induced by a wild type and a nitrogen fixation deficient strain, we propose that SPS has an important role in the control of carbon flux into different metabolic pathways in the symbiotic nodules. PMID:19898977

  17. Clastogenic activity of pure chlorophyll and anticlastogenic effects of equivalent amounts of crude extract of Indian spinach leaf and chlorophyllin following dietary supplementation to mice.

    PubMed

    Sarkar, D; Sharma, A; Talukder, G

    1996-01-01

    Dietary consumption of green vegetables has been associated with protection against mutagenic and clastogenic activity of genotoxicants. Chlorophyll, being present in all green plants, had earlier been suggested to be the principal factor involved. Mice were administered (i) crude aqueous extract of leaf of Indian spinach, Beta vulgaris L. var.benghalensis Hort., and equivalent amounts of (ii) chlorophyll extracted from the leaf; (iii) purified chlorophyll, (iv) chlorophyllin, a sodium-copper derivative of chlorophyll; daily for 7 days. On day 7, one set of mice from each treatment was administered potassium dichromate-a known metallic clastogen. The mice were sacrificed after 24 hours. Chromosome preparations were made from bone marrow following the usual colchicine-air dry-Giemsa schedule. The cytogenetic endpoints scored were chromosomal aberrations and damaged cells. Crude leaf extract and chlorophyllin were nonclastogenic and reduced the clastogenic effects of potassium dichromate to the control distilled water level. Chlorophyll alone, whether extracted from the leaf or obtained in commercially purified form, was clastogenic and could reduce the effects of the chromium salt only to its own level. The protective action of the crude leaf extract may be attributed to the total effect of the interaction between the different components within the leaf extract, in which the clastogenicity of chlorophyll had been neutralized. PMID:8844993

  18. Nectar secretion requires sucrose phosphate synthases and the sugar transporter SWEET9.

    PubMed

    Lin, I Winnie; Sosso, Davide; Chen, Li-Qing; Gase, Klaus; Kim, Sang-Gyu; Kessler, Danny; Klinkenberg, Peter M; Gorder, Molly K; Hou, Bi-Huei; Qu, Xiao-Qing; Carter, Clay J; Baldwin, Ian T; Frommer, Wolf B

    2014-04-24

    Angiosperms developed floral nectaries that reward pollinating insects. Although nectar function and composition have been characterized, the mechanism of nectar secretion has remained unclear. Here we identify SWEET9 as a nectary-specific sugar transporter in three eudicot species: Arabidopsis thaliana, Brassica rapa (extrastaminal nectaries) and Nicotiana attenuata (gynoecial nectaries). We show that SWEET9 is essential for nectar production and can function as an efflux transporter. We also show that sucrose phosphate synthase genes, encoding key enzymes for sucrose biosynthesis, are highly expressed in nectaries and that their expression is also essential for nectar secretion. Together these data are consistent with a model in which sucrose is synthesized in the nectary parenchyma and subsequently secreted into the extracellular space via SWEET9, where sucrose is hydrolysed by an apoplasmic invertase to produce a mixture of sucrose, glucose and fructose. The recruitment of SWEET9 for sucrose export may have been a key innovation, and could have coincided with the evolution of core eudicots and contributed to the evolution of nectar secretion to reward pollinators. PMID:24670640

  19. Circadian Regulation of Sucrose Phosphate Synthase Activity in Tomato by Protein Phosphatase Activity.

    PubMed Central

    Jones, T. L.; Ort, D. R.

    1997-01-01

    Sucrose phosphate synthase (SPS), a key enzyme in sucrose biosynthesis, is regulated by protein phosphorylation and shows a circadian pattern of activity in tomato. SPS is most active in its dephosphorylated state, which normally coincides with daytime. Applying okadaic acid, a potent protein phosphatase inhibitor, prevents SPS activation. More interesting is that a brief treatment with cycloheximide, a cytoplasmic translation inhibitor, also prevents the light activation of SPS without any effect on the amount of SPS protein. Cordycepin, an inhibitor of transcript synthesis and processing, has the same effect. Both of these inhibitors also prevent the activation phase of the circadian rhythm in SPS activity. Conversely, cycloheximide and cordycepin do not prevent the decline in circadian SPS activity that normally occurs at night. These observations indicate that SPS phosphatase activity but not SPS kinase activity is controlled, directly or indirectly, at the level of gene expression. Taken together, these data imply that there is a circadian rhythm controlling the transcription of a protein phosphatase that subsequently dictates the circadian rhythm in SPS activity via effects on this enzyme's phosphorylation state. PMID:12223667

  20. Summer (sub-arctic) versus winter (sub-tropical) production affects on spinach leaf bio-nutrients: Vitamins (C, E, Folate, K1, provitamin A), lutein, phenolics, and antioxidants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Comparison of spinach (Spinacia oleracea L.) cultivars Lazio and Samish grown during the summer solstice in the sub-arctic versus the winter solstice in the sub-tropics provided insight into interactions between plant environment (day length, light intensity, ambient temperatures), cultivar and leaf...

  1. Inhibition of Bacterial Pathogens in Medium and on Spinach Leaf Surfaces using Plant-Derived Antimicrobials Loaded in Surfactant Micelles.

    PubMed

    Ruengvisesh, Songsirin; Loquercio, Andre; Castell-Perez, Elena; Taylor, T Matthew

    2015-11-01

    Encapsulation of hydrophobic plant essential oil components (EOC) into surfactant micelles can assist the decontamination of fresh produce surfaces from bacterial pathogens during postharvest washing. Loading of eugenol and carvacrol into surfactant micelles of polysorbate 20 (Tween 20), Surfynol 485W, sodium dodecyl sulfate (SDS), and CytoGuard LA 20 (CG20) was determined by identification of the EOC/surfactant-specific maximum additive concentration (MAC). Rheological behavior of dilute EOC-containing micelles was then tested to determine micelle tolerance to shearing. Antimicrobial efficacy of EOC micelles against Escherichia coli O157:H7 and Salmonella enterica serotype Saintpaul was first evaluated by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Pathogen-inoculated spinach was treated with eugenol-containing micelles applied via spraying or immersion methods. SDS micelles produced the highest MACs for EOCs, while Tween 20 loaded the lowest amount of EOCs. Micelles demonstrated Newtonian behavior in response to shearing. SDS and CG20-derived micelles containing EOCs produced the lowest MICs and MBCs for pathogens. E. coli O157:H7 and S. Saintpaul were reduced on spinach surfaces by application of eugenol micelles, though no differences in numbers of surviving pathogens were observed when methods of antimicrobial micelle application (spraying, immersion) was compared (P ? 0.05). Data suggest eugenol in SDS and CG20 micelles may be useful for produce surface decontamination from bacterial pathogens during postharvest washing. PMID:26444985

  2. 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 π-π* 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.

  3. 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

  4. Testing models of fatty acid transfer and lipid synthesis in spinach leaf using in vivo oxygen-18 labeling

    SciTech Connect

    Pollard, M.; Ohlrogge, J.

    1999-12-01

    Oxygen-18 labeling has been applied to the study of plant lipid biosynthesis for the first time. [{sup 13}C{sub 2}{sup 18}O{sub 2}]Acetate was incubated with spinach (Spinacia oleracea) leaves and the {sup 18}O content in fatty acid methyl esters isolated from different lipid classes measured by gas chromatography-mass spectrometry. Fatty acids isolated from lipids synthesized within the plastid, such as monogalactosyldiacylglycerol, show an {sup 18}O content consistent with the exogenous acetate undergoing a single activation step and with the direct utilization of acyl-acyl carrier protein by the acyl transferases of the chloroplast. In contrast, fatty acids isolated from lipids assembled in the cytosol, such as phosphatidylcholine, show a 50% reduction in the {sup 18}O content. This is indicative of export of the fatty acyl groups from the plastid via a free carboxylate anion, and is consistent with the acyl-acyl carrier protein thioesterase:acyl-coenzyme A (CoA) synthetase mediated export mechanism. If this were not the case and the acyl group was transferred directly from acyl-acyl carrier protein to an acyl acceptor on the cytosolic side, there would be either complete retention of {sup 18}O or, less likely, complete loss of {sup 18}O, but not a 50% loss of {sup 18}O. Thus, existing models for fatty acid transfer from the plastid and for spatially separate synthesis of prokaryotic and eukaryotic lipids have both been confirmed.

  5. Hurdle enhancement of slightly acidic electrolyzed water antimicrobial efficacy on Chinese cabbage, lettuce, sesame leaf and spinach using ultrasonication and water wash.

    PubMed

    Forghani, Fereidoun; Oh, Deog-Hwan

    2013-10-01

    Slightly acidic electrolyzed water (SAEW) is well known as a good sanitizer against foodborne pathogens on fresh vegetables. However, microbial reductions from SAEW treatment are not enough to ensure produce safety. Therefore, it is necessary to improve its antimicrobial efficiency by combining it with other appropriate approaches. This study examined the microbicidal activity of SAEW (pH 5.2-5.5, oxidation reduction potential 500-600mV, available chlorine concentration 21-22mg/l) on Chinese cabbage, lettuce, sesame leaf and spinach, four common fresh vegetables in Korea under same laboratory conditions. Subsequently, effects of ultrasonication and water wash to enhance the sanitizing efficacy of SAEW were studied, separately. Finally, an optimized simple and easy approach consisting of simultaneous SAEW treatment with ultrasonication (3min) followed by water wash (150rpm, 1min) was developed (SAEW+US-WW). This newly developed hurdle treatment significantly enhanced the microbial reductions compared to SAEW treatment alone, SAEW treatment with ultrasonication (SAEW+US) and SAEW treatment followed by water wash (SAEW-WW) at room temperature (232C). Microbial reductions of yeasts and molds, total bacteria count and inoculated Escherichia coli O157:H7 and Listeria monocytogenes were in the range of 1.76-2.8log cfu/g on different samples using the new hurdle approach. PMID:23764218

  6. 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. )

    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.

  7. Mild Water Stress of Phaseolus vulgaris Plants Leads to Reduced Starch Synthesis and Extractable Sucrose Phosphate Synthase Activity 1

    PubMed Central

    Vassey, Terry L.; Sharkey, Thomas D.

    1989-01-01

    Mild water stress, on the order of ?1.0 megapascals xylem water potential, can reduce the rate of photosynthesis and eliminate the inhibition of photosynthesis caused by O2 in water-stress-sensitive plants such as Phaseolus vulgaris. To investigate the lack of O2 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 ?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 CO2 supply caused by stomatal closure leads to a reduction in the capacity for both starch and sucrose synthesis. This causes the reduced O2 inhibition and abrupt CO2 saturation of photosynthesis. PMID:16666665

  8. The Structure of Sucrose Phosphate Synthase from Halothermothrix orenii Reveals Its Mechanism of Action and Binding Mode

    SciTech Connect

    Chua,T.; Bujnicki, J.; Tan, T.; Huynh, F.; Patel, B.; Sivaraman, J.; Ogimoto, Y.; Miyano, K.; Sawa, H.

    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.

  9. Effect of spinach cultivar and strain variation on survival of Escherichia coli O157:H7 on spinach leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Escherichia coli O157:H7 outbreaks of infections associated with the consumption of fresh produce have increased in recent years. Bacterial cell surface appendages such as curli and the spinach leaf structure topography influence pathogen attachment and subsequent survival on spinach ...

  10. Conversion of L-sorbosone to L-ascorbic acid by a NADP-dependent dehydrogenase in bean and spinach leaf. [Phaseolus vulgaris L. ; Spinacia oleracea L

    SciTech Connect

    Loewus, M.W.; Bedgar, D.L.; Saito, Kazumi; Loewus, F.A. )

    1990-11-01

    An NADP-dependent dehydrogenase catalyzing the conversion of L-sorbosone to L-ascorbic acid has been isolated from Phaseolus vulgaris L. and Spinacia oleracea L. and partially purified. It is stable at {minus}20{degree}C for up to 8 months. Molecular masses, as determined by gel filtration, were 21 and 29 kilodaltons for bean and spinach enzymes, respectively. K{sub m} for sorbosone were 12 {plus minus} 2 and 18 {plus minus} 2 millimolar and for NADP{sup +}, 0.14 {plus minus} 0.05 and 1.2 {plus minus} 0.5 millimolar, for bean and spinach, respectively. Lycorine, a purported inhibitor of L-ascorbic acid biosynthesis, had no effect on the reaction.

  11. Characterization of technetium species induced in spinach

    SciTech Connect

    Harms, A.V.; Krijger, G.C.; Elteren, J.T. van; Goeij, J.J.M. de

    1999-08-01

    Plants have the ability to accumulate the long-lived fission product {sup 99}Tc. In this work, an attempt was made to separate and characterize technetium species induced by spinach plants (Spinacia oleracea L.) grown on a TcO{sub 4}{sup {minus}} containing nutrient solution. Combination of data obtained with selective extraction and chromatography gave us insight into Tc speciation in spinach plants. The following classes of Tc species in spinach leaf homogenate were found after an incubation period of 11 d: TcO{sub 4}{sup {minus}} (ca. 7%), Tc{sup V}-cysteine (ca. 25%), Tc bound to insoluble cell-wall polysaccharides (ca. 17%), Tc bound to proteins (ca. 26%), and hydrophilic non-protein Tc species (ca. 25%). These results may yield a new insight into the metabolic pathways of Tc in plants.

  12. Carbonic Anhydrase of Spinach

    PubMed Central

    Jacobson, Bruce S.; Fong, Franklin; Heath, Robert L.

    1975-01-01

    Carbonic anhydrase activity was determined in spinach (Spinacia oleracea) leaf organelles isolated on sucrose density gradients and was found to be predominantly in the intact chloroplast fraction. The small amount of activity associated with the mitochondrial fractions was probably due to intact chloroplast contamination. No activity could be associated with the broken chloroplast or microbody fractions. Based upon inhibitor studies, carbonic anhydrase was found to be around 2 mm in the chloroplast. Ethoxzolamide, an inhibitor of carbonic anhydrase, reduced CO2 fixation in intact chloroplasts. The concentration required to inhibit CO2 fixation 20 to 40% was in excess of that required to inhibit the purified enzyme. The inhibition was partially reversed by CO2. Ethoxzolamide had no effect on photosynthetic NADP reduction or photophosphorylation measured by methyl viologen reduction. The physiological role of carbonic anhydrase was shown not to be associated with CO2 diffusion or CO2 concentration. It is proposed that other functions of carbonic anhydrase could be the protection against denaturation by transient localized changes in pH or the hydration of compounds other than CO2. PMID:16659104

  13. Leaf photosynthesis and carbohydrates of CO2-enriched maize and grain sorghum exposed to a short period of soil water deficit during vegetative development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought was imposed on 26-day old corn and grain sorghum grown in carbon dioxide (CO2) at 360 (ambient) or 720 (elevated) ppm. Midday leaf CO2 exchange rates (CER), and afternoon carbohydrate concentrations and activities of sucrose phosphate synthase (SPS) & adenosine 5’-diphosphoglucose pyrophosph...

  14. International collaborative study of the endogenous reference gene, sucrose phosphate synthase (SPS), used for qualitative and quantitative analysis of genetically modified rice.

    PubMed

    Jiang, Lingxi; Yang, Litao; Zhang, Haibo; Guo, Jinchao; Mazzara, Marco; Van den Eede, Guy; Zhang, Dabing

    2009-05-13

    One rice ( Oryza sativa ) gene, sucrose phosphate synthase (SPS), has been proven to be a suitable endogenous reference gene for genetically modified (GM) rice detection in a previous study. Herein are the reported results of an international collaborative ring trial for validation of the SPS gene as an endogenous reference gene and its optimized qualitative and quantitative polymerase chain reaction (PCR) systems. A total of 12 genetically modified organism (GMO) detection laboratories from seven countries participated in the ring trial and returned their results. The validated results confirmed the species specificity of the method through testing 10 plant genomic DNAs, low heterogeneity, and a stable single-copy number of the rice SPS gene among 7 indica varieties and 5 japonica varieties. The SPS qualitative PCR assay was validated with a limit of detection (LOD) of 0.1%, which corresponded to about 230 copies of haploid rice genomic DNA, while the limit of quantification (LOQ) for the quantitative PCR system was about 23 copies of haploid rice genomic DNA, with acceptable PCR efficiency and linearity. Furthermore, the bias between the test and true values of eight blind samples ranged from 5.22 to 26.53%. Thus, we believe that the SPS gene is suitable for use as an endogenous reference gene for the identification and quantification of GM rice and its derivates. PMID:19326953

  15. Expression patterns, activities and carbohydrate-metabolizing regulation of sucrose phosphate synthase, sucrose synthase and neutral invertase in pineapple fruit during development and ripening.

    PubMed

    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

  16. Effect of spinach cultivar and bacterial adherence factors on survival of Escherichia coli O157:H7 on spinach leaves.

    PubMed

    Macarisin, Dumitru; Patel, Jitendra; Bauchan, Gary; Giron, Jorge A; Ravishankar, Sadhana

    2013-11-01

    Similar to phytopathogens, human bacterial pathogens have been shown to colonize the plant phylloplane. In addition to environmental factors, such as temperature, UV, relative humidity, etc., the plant cultivar and, specifically, the leaf blade morphological characteristics may affect the persistence of enteropathogens on leafy greens. This study was conducted to evaluate the effect of cultivar-dependent leaf topography and the role of strain phenotypic characteristics on Escherichia coli O157:H7 persistence on organic spinach. Spinach cultivars Emilia, Lazio, Space, and Waitiki were experimentally inoculated with the foodborne E. coli O157:H7 isolate EDL933 and its isogenic mutants deficient in cellulose, curli, or both curli and cellulose production. Leaves of 6-week-old plants were inoculated with 6.5 log CFU per leaf in a biosafety level 2 growth chamber. At 0, 1, 7, and 14 days, E. coli O157:H7 populations were determined by plating on selective medium and verified by laser scanning confocal microscopy. Leaf morphology (blade roughness and stoma density) was evaluated by low-temperature and variable-pressure scanning electron microscopy. E. coli O157:H7 persistence on spinach was significantly affected by cultivar and strain phenotypic characteristics, specifically, the expression of curli. Leaf blade roughness and stoma density influenced the persistence of E. coli O157:H7 on spinach. Cultivar Waitiki, which had the greatest leaf roughness, supported significantly higher E. coli O157:H7 populations than the other cultivars. These two morphological characteristics of spinach cultivars should be taken into consideration in developing intervention strategies to enhance the microbial safety of leafy greens. PMID:24215684

  17. Nitrogen Uptake in Spinach

    NASA Astrophysics Data System (ADS)

    Ramirez, J.; VanBenthem, P.

    2013-12-01

    A plant's absorption of nitrogen can be encouraged by a variety of environmental factors, especially the application of fertilizers. As a common limiting factor in plant growth, not up taking enough nitrogen can be a result of an unhealthy plant. Moreover, as farmers seek out methods to increase growth of plants, fertilizers are used as a solution to the issue of nitrogen deficiency to incorporate additional nitrogen from chemical or organic sources, by not using the right fertilizer can greatly affect the plats. The point of this research project is to determine the effect of various fertilizers on the plant growth, and to correlate the measured nitrogen, water and chlorophyll content in spinach leaves. Spinach leaves were used because they are known to quickly uptake chemicals in the environment. The spinach plants were exposed to four different growing parameters, which are referred to as control, ammonium nitrate, MiracleGro , and organic. The spinach was originally placed in nitrogen deficient soil with only 2.2x10 4 weight percent (wt. %) nitrogen. The leaves in the control group were grown in this nitrogen deficient soil without any fertilizer added. Ammomium nitrate and MiracleGro were added to the spinach in the A and MG groups, respectively, and organic chicken stool was used for the O group. By using a spectral imaging system and flame combustion techniques, the chlorophyll content can be related to the nitrogen content in the spinach leaves. In these spinach leaves, nitrogen and chlorophyll content were measured, chlorophyll is a green pigment that plays a crucial role in producing nutrients for green plants. The lack of chlorophyll will allow the plant to become susceptible to diseases, so it is extremely important that the plants have a high content of chlorophyll. The role of nitrogen in chlorophyll is very important and helps in the creation of chlorophyll; therefore it is necessary that an appropriate amount of nitrogen is added for optimal growth and nutrient content. A common method of increasing nitrogen's availability is by adding fertilizer to plants. Fertilizers come in many varieties, ranging from organic to synthetic. Organic fertilizers differ from their synthetic counterparts in that they contain less artificial substances. Preliminary results of this study show that the organic fertilizer promoted growth of chlorophyll in the spinach leaves. The highest peaks in our results are due to the light absorbance of chlorophyll. The spectra also showed the organic fertilizer had the highest chlorophyll content, unlike the ammonium sulfate which had the last amount. Surprisingly, the control performed slightly better than the MiracleGro, which would not be expected, since MiracleGro is a widely used fertilizer, it was expected that this would lead to the highest chlorophyll content. It is unexpected the soil with trace nitrogen content was able to produce spinach with this relatively high content of chlorophyll. It is imperative to examine how different types of nitrogen additives affect spinach growth. The consequences of fertilizer overuse are destructive to both the plant and its environment, as well as to the humans that consume the resulting produce. The preliminary results of this experiment gave insight into the effectiveness of various kinds of fertilizers and may be able to encourage farmers to use organic fertilizers from natural sources for optimal nutrients and growth of their crops.

  18. Choline Synthesis in Spinach in Relation to Salt Stress.

    PubMed Central

    Summers, P. S.; Weretilnyk, E. A.

    1993-01-01

    Choline metabolism was examined in spinach (Spinacia oleracea L.) plants growing under nonsaline and saline conditions. In spinach, choline is required for phosphatidylcholine synthesis and as a precursor for the compatible osmolyte glycine betaine (betaine). When control (nonsalinized) leaf discs were incubated for up to 2 h with [1,2-14C]ethanolamine, label appeared in the N-methylated derivatives of phosphoethanolamine including phosphomono-, phosphodi-, and phosphotri- (i.e. phosphocholine) methyl-ethanolamine, as well as in choline and betaine, whereas no radioactivity could be detected in the mono- and dimethylated derivatives of the free base ethanolamine. Leaf discs from salinized plants showed the same pattern of labeling, although the proportion of label that accumulated in betaine was almost 3-fold higher in the salinized leaf discs. Enzymes involved in choline metabolism were assayed in crude leaf extracts of plants. The activites of ethanolamine kinase and of the three S-adenosylmethionine:phospho-base N-methyltransferase enzymes responsible for N-methylating phosphoethanolamine to phosphocholine were all higher in extracts of plants salinized step-wise to 100, 200, or 300 mM NaCI compared with controls. In contrast, choline kinase, phosphocholine phosphatase, and cytidine 5[prime]-triphosphate: phosphocholine cytidylyltransferase activities showed little variation with salt stress. Thus, the increased diversion of choline to betaine in salt-stressed spinach appears to be mediated by the increased activity of several key enzymes involved in choline biosynthesis. PMID:12232019

  19. Physical and mechanical properties of spinach for whole-surface online imaging inspection

    NASA Astrophysics Data System (ADS)

    Tang, Xiuying; Mo, Chang Y.; Chan, Diane E.; Peng, Yankun; Qin, Jianwei; Yang, Chun-Chieh; Kim, Moon S.; Chao, Kuanglin

    2011-06-01

    The physical and mechanical properties of baby spinach were investigated, including density, Young's modulus, fracture strength, and friction coefficient. The average apparent density of baby spinach leaves was 0.5666 g/mm3. The tensile tests were performed using parallel, perpendicular, and diagonal directions with respect to the midrib of each leaf. The test results showed that the mechanical properties of spinach are anisotropic. For the parallel, diagonal, and perpendicular test directions, the average values for the Young's modulus values were found to be 2.137MPa, 1.0841 MPa, and 0.3914 MPa, respectively, and the average fracture strength values were 0.2429 MPa, 0.1396 MPa, and 0.1113 MPa, respectively. The static and kinetic friction coefficient between the baby spinach and conveyor belt were researched, whose test results showed that the average coefficients of kinetic and maximum static friction between the adaxial (front side) spinach leaf surface and conveyor belt were 1.2737 and 1.3635, respectively, and between the abaxial (back side) spinach leaf surface and conveyor belt were 1.1780 and 1.2451 respectively. These works provide the basis for future development of a whole-surface online imaging inspection system that can be used by the commercial vegetable processing industry to reduce food safety risks.

  20. Betaine aldehyde dehydrogenase isozymes of spinach

    SciTech Connect

    Hanson, A.D.; Weretilnyk, E.A.; Weigel, P.

    1986-04-01

    Betaine is synthesized in spinach chloroplasts via the pathway Choline ..-->.. Betaine Aldehyde ..-->.. Betaine; the second step is catalyzed by betaine aldehyde dehydrogenase (BADH). The subcellular distribution of BADH was determined in leaf protoplast lysates; BADH isozymes were separated by 6-9% native PAGE. The chloroplast stromal fraction contains a single BADH isozyme (number1) that accounts for > 80% of the total protoplast activity; the extrachloroplastic fraction has a minor isozyme (number2) which migrates more slowly than number1. Both isozymes appear specific for betaine aldehyde, are more active with NAD than NADP, and show a ca. 3-fold activity increase in salinized leaves. The phenotype of a natural variant of isozyme number1 suggests that the enzyme is a dimer.

  1. In vitro liberation of carotenoids from spinach and Asia salads after different domestic kitchen procedures.

    PubMed

    Eriksen, Jane N; Luu, Amy Y; Dragsted, Lars O; Arrigoni, Eva

    2016-07-15

    Green-leafy vegetables are rich in nutritionally important constituents including carotenoids. Their potential health benefits depend among others on their liberation from the plant matrix. The aim of the present study was to evaluate the effect of particle size and heat treatments on lutein and β-carotene liberation from spinach and Asia salads by applying an in vitro digestion protocol and UHPLC analysis. Reduction of particle size resulted in a three- to fourfold increase in liberation of lutein and β-carotene when comparing whole leaf and puree preparations of spinach. However, this positive effect was shown to be nullified by the severe heat impact during stir-frying of minced spinach, showing that domestic treatments need to be chosen carefully to maximise carotenoid liberation. Steaming significantly improved lutein liberation from Asia salads, but had no or a negative effect in spinach samples, possibly due to differences in liberation or degradation between the two plant matrices. PMID:26948584

  2. Understanding the molecular mechanism of transcriptional regulation of banana Sucrose phosphate synthase (SPS) gene during fruit ripening: an insight into the functions of various cis-acting regulatory elements.

    PubMed

    Choudhury, Swarup Roy; Roy, Sujit; Singh, Sanjay Kumar; Sengupta, Dibyendu N

    2010-05-01

    Recently, we have reported the characterization of promoter region of Sucrose phosphate synthase (SPS) gene in banana and investigated the role of some cis-elements/motifs, present in the promoter of SPS, in the transcriptional regulation of the gene. DNA-protein interaction studies have demonstrated the presence of specific trans-acting factors which showed specific interactions with ethylene, auxin, low temperature and light responsive elements in regulating SPS transcription. Transient expression analyses have demonstrated the functional significance of the various cis-acting regulatory elements present in banana SPS promoter in regulating SPS expression during ripening. (1) Here, we have further discussed the possible role of these regulatory sequences in the regulation of transcriptional network and comment on their function in relation to sucrose metabolism during banana fruit ripening. PMID:20139735

  3. Ammonium reduces oxalate accumulation in different spinach (Spinacia oleracea L.) genotypes by inhibiting root uptake of nitrate.

    PubMed

    Liu, Xiaoxia; Lu, Lingli; Chen, Qiuhui; Ding, Wenya; Dai, Peibin; Hu, Yan; Yu, Yan; Jin, Chongwei; Lin, Xianyong

    2015-11-01

    Excessive accumulation of oxalate negatively affects nutritional value of many vegetables, such as spinach (Spinacia oleracea L.). Mixed solution of ammonium and nitrate could effectively reduce oxalate accumulation, while the mechanism involved remains unknown. High (Heizhenzhu) and low (Weilv) oxalate-accumulated spinach genotypes were used in this study to investigate the association of oxalate accumulation and root uptake of nitrogen. Exposure of increasing nitrate or mixed-nitrogen (nitrate:ammonium = 1:1) significantly increased leaf total and soluble oxalate contents. In contrast, increasing ammonium did not result in elevation of leaf oxalate. Correlation analysis confirmed that leaf oxalate accumulation was positively associated with root uptake of nitrate but not ammonium. Moreover, addition of ammonium significantly reduced nitrate uptake rate, and subsequently decreased leaf oxalate accumulation. The results suggest that oxalate synthesis in spinach leaves is associated with its root uptake of nitrate, and ammonium is able to reduce oxalate accumulation by inhibiting uptake of nitrate. PMID:25976827

  4. [Determination of uranium in spinach].

    PubMed

    Kishi, Eri; Yutani, Aiko; Ozaki, Asako; Shinya, Masanao; Katahira, Kenshi; Ooshima, Tomoko; Shimizu, Mitsuru

    2013-01-01

    After the severe accident at the Fukushima-1 Nuclear Power Plant in March 2011, radioactive contamination of food has become a matter of serious concern in Japan. There is considerable information about radioactive iodine and cesium, but little is known about uranium contamination. We determined uranium content in spinach by the Japanese official method (Manual on Radiation Measurement of Food in Emergency Situations). In the preliminary study, we confirmed that the use of a microwave digestion system for preparing the test solution of spinach could shorten the testing time and give acceptable results. The manual recommends the use of two elements (Tl and Bi) as internal standards for measurement of uranium by ICP-MS. We found that Tl was more suitable than Bi to quantify trace amounts of uranium in spinach. However, it was necessary to determine Tl or Bi concentrations in the sample before analysis, since some samples of spinach contained significant amounts of these elements. The uranium contents of 9 spinach samples bought in April and May 2011 were less than 10 ?g/kg, which are very low compared to the provisional regulatory limit in Japan. PMID:23676689

  5. Spinach and mustard greens response to soil type, sulfur addition and lithium level

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A greenhouse experiment was conducted near Weslaco, Texas (Lat. 26o 8' N, Long. 97o 57' W) between Dec. 2006 and Feb 2007 to evaluate the effect of soil type, added sulfur and lithium level on the growth and leaf nutrients, particularly biofortified levels of Li and S, in spinach and mustard gree...

  6. Characterization of multiple SPS knockout mutants reveals redundant functions of the four Arabidopsis sucrose phosphate synthase isoforms in plant viability, and strongly indicates that enhanced respiration and accelerated starch turnover can alleviate the blockage of sucrose biosynthesis.

    PubMed

    Bahaji, Abdellatif; Baroja-Fernández, Edurne; Ricarte-Bermejo, Adriana; Sánchez-López, Ángela María; Muñoz, Francisco José; Romero, Jose M; Ruiz, María Teresa; Baslam, Marouane; Almagro, Goizeder; Sesma, María Teresa; Pozueta-Romero, Javier

    2015-09-01

    We characterized multiple knock-out mutants of the four Arabidopsis sucrose phosphate synthase (SPSA1, SPSA2, SPSB and SPSC) isoforms. Despite their reduced SPS activity, spsa1/spsa2, spsa1/spsb, spsa2/spsb, spsa2/spsc, spsb/spsc, spsa1/spsa2/spsb and spsa2/spsb/spsc mutants displayed wild type (WT) vegetative and reproductive morphology, and showed WT photosynthetic capacity and respiration. In contrast, growth of rosettes, flowers and siliques of the spsa1/spsc and spsa1/spsa2/spsc mutants was reduced compared with WT plants. Furthermore, these plants displayed a high dark respiration phenotype. spsa1/spsb/spsc and spsa1/spsa2/spsb/spsc seeds poorly germinated and produced aberrant and sterile plants. Leaves of all viable sps mutants, except spsa1/spsc and spsa1/spsa2/spsc, accumulated WT levels of nonstructural carbohydrates. spsa1/spsc leaves possessed high levels of metabolic intermediates and activities of enzymes of the glycolytic and tricarboxylic acid cycle pathways, and accumulated high levels of metabolic intermediates of the nocturnal starch-to-sucrose conversion process, even under continuous light conditions. Results presented in this work show that SPS is essential for plant viability, reveal redundant functions of the four SPS isoforms in processes that are important for plant growth and nonstructural carbohydrate metabolism, and strongly indicate that accelerated starch turnover and enhanced respiration can alleviate the blockage of sucrose biosynthesis in spsa1/spsc leaves. PMID:26259182

  7. Role of curli and cellulose expression in adherence of Escherichia coli O157:H7 to spinach leaves.

    PubMed

    Macarisin, Dumitru; Patel, Jitendra; Bauchan, Gary; Giron, Jorge A; Sharma, Vijay K

    2012-02-01

    Shiga-toxigenic Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh produce. It is generally recognized that bacterial attachment to vegetal matrices constitutes the first step in contamination of fresh produce. Cellular appendages, such as curli fibers, and cellulose, a constituent of extracellular matrix, have been suggested to be involved in E. coli attachment and persistence in fresh produce. A comparative evaluation was conducted on the ability of Shiga toxin-producing E. coli O157:H7 strains EDL933 and 86-24, linked to two independent foodborne disease outbreaks in humans, and their mutants deficient in curli and/or cellulose expression to colonize and to firmly attach to spinach leaf. Inoculated spinach leaves were incubated at 22°C, and at 0, 24, and 48 h after incubation loosely and strongly attached E. coli O157:H7 populations were determined. Curli-expressing E. coli O157:H7 strains developed stronger association with leaf surface, whereas curli-deficient mutants attached to spinach at significantly (p<0.01) lower numbers. Attachment of cellulose-impaired mutants to spinach leaves was not significantly different from that of curliated strains. The relative attachment strength of E. coli O157:H7 to spinach increased with incubation time for the curli-expressing strains. Laser scanning confocal microscopy (LSCM) analysis of inoculated leaves revealed that curli-expressing E. coli O157:H7 were surrounded by extracellular structures strongly immunostained with anti-curli antibodies. Production of cellulose was not required to develop strong attachment to spinach leaf. These results indicate that curli fibers are essential for strong attachment of E. coli O157:H7 to spinach whereas cellulose is dispensable. PMID:22315954

  8. Role of curli and cellulose expression in adherence of Escherichia coli O157:H7 to spinach leaves.

    TOXLINE Toxicology Bibliographic Information

    Macarisin D; Patel J; Bauchan G; Giron JA; Sharma VK

    2012-02-01

    Shiga-toxigenic Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh produce. It is generally recognized that bacterial attachment to vegetal matrices constitutes the first step in contamination of fresh produce. Cellular appendages, such as curli fibers, and cellulose, a constituent of extracellular matrix, have been suggested to be involved in E. coli attachment and persistence in fresh produce. A comparative evaluation was conducted on the ability of Shiga toxin-producing E. coli O157:H7 strains EDL933 and 86-24, linked to two independent foodborne disease outbreaks in humans, and their mutants deficient in curli and/or cellulose expression to colonize and to firmly attach to spinach leaf. Inoculated spinach leaves were incubated at 22°C, and at 0, 24, and 48 h after incubation loosely and strongly attached E. coli O157:H7 populations were determined. Curli-expressing E. coli O157:H7 strains developed stronger association with leaf surface, whereas curli-deficient mutants attached to spinach at significantly (p<0.01) lower numbers. Attachment of cellulose-impaired mutants to spinach leaves was not significantly different from that of curliated strains. The relative attachment strength of E. coli O157:H7 to spinach increased with incubation time for the curli-expressing strains. Laser scanning confocal microscopy (LSCM) analysis of inoculated leaves revealed that curli-expressing E. coli O157:H7 were surrounded by extracellular structures strongly immunostained with anti-curli antibodies. Production of cellulose was not required to develop strong attachment to spinach leaf. These results indicate that curli fibers are essential for strong attachment of E. coli O157:H7 to spinach whereas cellulose is dispensable.

  9. 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.

    PubMed

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

    2008-12-01

    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 ethylene strongly stimulated SPS transcript accumulation, auxin and cold treatment only marginally increased the abundance of SPS mRNA level, while wounding negatively regulated SPS gene expression. Conversely, SPS transcript level was distinctly increased by constant exposure to white light. Protein level, enzymatic activity of SPS and sucrose synthesis were substantially increased by ethylene and increased exposure to white light conditions as compared to other treatments. To further study the transcriptional regulation of SPS in banana fruit, the promoter region of SPS gene was cloned and some cis-acting regulatory elements such as a reverse GCC-box ERE, two ARE motifs (TGTCTC), one LTRE (CCGAA), a GAGA-box (GAGA...) and a GATA-box LRE (GATAAG) were identified along with the TATA and CAAT-box. DNA-protein interaction studies using these cis-elements indicated a highly specific cis-trans interaction in the banana nuclear extract. Furthermore, we specifically studied the light responsive characteristics of GATA-box containing synthetic as well as native banana SPS promoter. Transient expression assays using banana SPS promoter have also indicated the functional importance of the SPS promoter in regulating gene expression. Together, these results provide insights into the transcriptional regulation of banana SPS gene in response to phytohormones and other environmental factors during fruit ripening. PMID:18830708

  10. Effect of Light and Chilling Temperatures on Chilling-sensitive and Chilling-resistant Plants. Pretreatment of Cucumber and Spinach Thylakoids in Vivo and in Vitro.

    PubMed

    Garber, M P

    1977-05-01

    The effects of chilling temperatures, in light or dark, on the isolated thylakoids and leaf discs of cucumber (Cucumis sativa L. "Marketer") and spinach (Spinacia oleracea L. "Bloomsdale") were studied. The pretreatment of isolated thylakoids and leaf discs at 4 C in the dark did not affect the phenazine methosulfate-dependent phosphorylation, proton uptake, osmotic response to sucrose, Ca(2+)-dependent ATPase activity, or chlorophyll content. Exposure of cucumber cotyledon discs and isolated thylakoids of cucumber and spinach to 4 C in light resulted in a rapid inactivation of the thylakoids. The sequence of activities or components lost during inactivation (starting with the most sensitive) are: phenazine methosulfate-dependent cyclic phosphorylation, proton uptake, osmotic response to sucrose, Ca(2+)-dependent ATPase activity, and chlorophyll. The rate of loss of proton uptake, osmotic response to sucrose, Ca(2+)-dependent ATPase activity and chlorophyll is similar for isolated cucumber and spinach thylakoids, whereas spinach thylakoids are more resistant to the loss of phenazine methosulfate-dependent phosphorylation. The thylakoids of spinach leaf discs were unaffected by exposure to 4 C in light. The results question whether the extreme resistance of spinach thylakoids treated in vivo is solely a function of the chloroplast thylakoid membranes and establish the validity of using in vitro results to make inferences about cucumber thylakoids treated in vivo at 4 C in light. PMID:16659980

  11. 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...

  12. 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 33C, 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 10C. This enteric pathogen also persisted in the rhizosphere of spinach for prolonged periods of time at 16C, 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 10C. 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

  13. Analysis of energy utilization in spinach processing

    SciTech Connect

    Chhinnan, M.S.; Singh, R.P.; Pedersen, L.D.; Carroad, P.A.; Rose, W.W.; Jacob, N.L.

    1980-03-01

    The equipment and methods used to monitor the electrical and thermal energy consumed in various unit operations in a spinach processing plant are described and the results of a processing plant energy audit are presented. It is concluded that it requires 6.5 MJ of natural gas and fuel oil and 0.072 MJ of electric power to process one kg of new spinach; the energy intensive operations in spinach processing are associated with exhaust boxes, blanchers, and retorts; uniform product flow through the canning line is essential to energy conservation; and design improvements are needed for the blancher, exhaust box, and retort. (LCL)

  14. Choline oxidation by intact chloroplasts isolated directly from spinach leaves

    SciTech Connect

    Weigel, P.; Hanson, A.D.

    1986-04-01

    Illuminated chloroplasts derived from spinach leaf protoplasts synthesize betaine from choline via the intermediate betaine aldehyde (BAL) (PNAS 82:3678). Photosynthetically active chloroplasts isolated directly from spinach leaves oxidized (/sup 14/C)choline in the light at rates 10 times higher (25-80 nmol/mg chl b) than protoplast-derived chloroplasts. Up to 20% of the (/sup 14/C)choline supplied during a 30 min incubation was oxidized in the light; the main product was (/sup 14/C)BAL. Rates of (/sup 14/C)choline oxidation in darkness were only 5-30% of rates in light. Light-dependent (/sup 14/C)choline oxidation was abolished by DCMU and 5 mM DTT. Pre-illumination of the chloroplasts did not promote (/sup 14/C)choline oxidation in darkness. The uncouplers nigericin and CCCP at concentrations which eliminated CO/sub 2/-dependent O/sub 2/ evolution did not affect (/sup 14/C)choline oxidation in the light. They hypothesize that (/sup 14/C)choline oxidation is not dependent upon light activation of an enzymatic system or upon the electrochemical proton gradient but requires an oxidant generated in the light.

  15. Effects of Light and Spermine on Senescence of Hydrilla and Spinach Leaves 1

    PubMed Central

    Kar, Rup K.; Choudhuri, Monojit A.

    1986-01-01

    Light treatment markedly accelerated chlorophyll loss in Hydrilla (Hydrilla verticillata [L.f.] Royle) over dark treatment whereas such acceleration could not be observed in spinach (Spinacia oleracea L.) leaf segments. Spermine, a polyamine, retarded the loss of chlorophyll in the dark but markedly accelerated this loss in the light during senescence of Hydrilla leaves. However, such effect of spermine in the dark was not so pronounced in spinach. The loss of protein was slower in the light than in the dark in both the species. Spermine arrested the loss of protein (as in spinach) or even raised the protein level over initial (as in Hydrilla). Loss of both soluble and insoluble protein was slower in light than in darkness. Spermine treatment, either in light or darkness, markedly accelerated the loss of soluble protein but raised the level of insoluble protein over initial in both the species. The pattern of change in ?-amino nitrogen in either species could be correlated well with that of protein level. In Hydrilla, light increased the soluble protein fraction over initial and this rise was prevented by cycloheximide and not by chloramphenicol. Also, spermine augmented the protease activity (both acid and neutral) while light retarded the rise in protease activity during senescence of either species. Although spermine treatment reduced the leaching of ?-amino nitrogen and electrolytes in Hydrilla, it augmented the same in spinach. PMID:16664713

  16. Identification of an Acyl Donor in Steryl Ester Biosynthesis by Enzyme Preparations from Spinach Leaves

    PubMed Central

    Garcia, Raymond E.; Mudd, J. Brian

    1978-01-01

    A pathway for steryl ester biosynthesis in acetone powder preparations from spinach (Spinacia oleracea L.) leaves has been elucidated; free sterol and 1,2-diglyceride were the substrates. Although animals synthesize cholesteryl esters by three distinct biosynthetic pathways, none of these pathways utilizes 1,2-diglyceride as an acyl donor. Phosphatidylcholine, phosphatidic acid, triglyceride, 1,3-diglyceride, 1-monoglyceride, free fatty acid, and fatty acyl-CoA were not acyl donors for spinach leaf steryl ester biosynthesis in our assay system. The unstable 2 isomer of monoglyceride was not tested. It is possible that 1,2-diglyceride and 2-monoglyceride were both acyl donors for spinach leaf steryl ester biosynthesis. Acyl-labeled phosphatidylcholine and acyl-labeled phosphatidylethanolamine were rapidly degraded by acetone powder preparations to 1,2-diglyceride via phosphatidic acid. The 1,2-diglycerides were slowly metabolized to monoglycerides, triglycerides, free fatty acids, and steryl esters. The monoglycerides were rapidly degraded to free fatty acids and glycerol. PMID:16660515

  17. Protein prenylation in spinach chloroplasts

    PubMed Central

    Parmryd, Ingela; Andersson, Bertil; Dallner, Gustav

    1999-01-01

    Protein prenylation in plants was studied by in vivo metabolic 3H-mevalonate labeling in combination with a range of protein synthesis inhibitors. In spinach cotyledons, this posttranslational protein modification was found to be divided into two categories, one representing the conventional prenylation involving farnesyl and geranylgeranyl groups bound to cysteine residues via thioether linkages. This category revealed a similar pattern of prenylated proteins to that observed in mammalian cells and depends on nuclear gene expression. The other category was shown to represent a type of prenylation confined to chloroplasts. It depends on plastid gene expression and does not involve a thioether bond. The modifying isoprenoid could be released from the chloroplastic polypeptides by alkaline treatment and was identified as phytol upon GC-MS analysis. The phytol could readily be derived from all-trans-[3H]farnesol, which, like all-trans-[3H]geranylgeraniol, was taken up by the cotyledons, resulting in incorporation of radiolabel into proteins. PMID:10468564

  18. 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...

  19. Expression of holo and apo forms of spinach acyl carrier protein-I in leaves of transgenic tobacco plants.

    PubMed Central

    Post-Beittenmiller, M A; Schmid, K M; Ohlrogge, J B

    1989-01-01

    Acyl carrier protein (ACP) is a chloroplast-localized cofactor of fatty acid synthesis, desaturation, and acyl transfer. We have transformed tobacco with a chimeric gene consisting of the tobacco ribulose-1,5-bisphosphate carboxylase promoter and transit peptide and the sequence encoding the mature spinach ACP-I. Spinach ACP-I was expressed in the transformed plants at levels twofold to threefold higher than the endogenous tobacco ACPs as determined by protein immunoblots and assays of ACP in leaf extracts. In addition to these elevated levels of the holo form, there were high levels of apoACP-I, a form lacking the 4'-phosphopantetheine prosthetic group and not previously detected in vivo. The mature forms of both apoACP-I and holoACP-I were located in the chloroplasts, indicating that the transit peptide was cleaved and that attachment of the prosthetic group was not required for uptake into the plastid. There were also significant levels of spinach acyl-ACP-I, demonstrating that spinach ACP-I participated in tobacco fatty acid metabolism. Lipid analyses of the transformed plants indicated that the increased ACP levels caused no significant alterations in leaf lipid biosynthesis. PMID:2535529

  20. Comparison of two possible routes of pathogen contamination of spinach leaves in a hydroponic cultivation system.

    PubMed

    Koseki, Shigenobu; Mizuno, Yasuko; Yamamoto, Kazutaka

    2011-09-01

    The route of pathogen contamination (from roots versus from leaves) of spinach leaves was investigated with a hydroponic cultivation system. Three major bacterial pathogens, Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes, were inoculated into the hydroponic solution, in which the spinach was grown to give concentrations of 10? and 10 CFU/ml. In parallel, the pathogens were inoculated onto the growing leaf surface by pipetting, to give concentrations of 10? and 10 CFU per leaf. Although contamination was observed at a high rate through the root system by the higher inoculum (10? CFU) for all the pathogens tested, the contamination was rare when the lower inoculum (10 CFU) was applied. In contrast, contamination through the leaf occurred at a very low rate, even when the inoculum level was high. For all the pathogens tested in the present study, the probability of contamination was promoted through the roots and with higher inoculum levels. The probability of contamination was analyzed with logistic regression. The logistic regression model showed that the odds ratio of contamination from the roots versus from the leaves was 6.93, which suggested that the risk of contamination from the roots was 6.93 times higher than the risk of contamination from the leaves. In addition, the risk of contamination by L. monocytogenes was about 0.3 times that of Salmonella enterica subsp. enterica serovars Typhimurium and Enteritidis and E. coli O157:H7. The results of the present study indicate that the principal route of pathogen contamination of growing spinach leaves in a hydroponic system is from the plant's roots, rather than from leaf contamination itself. PMID:21902924

  1. Inactivation of Escherichia Coli O157:H7 Internalized in Romaine Lettuce and Baby Spinach Leaves:Sodium Hypochlorite Wash vs. Irradiation

    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...

  2. 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...

  3. 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...

  4. Iodine uptake by spinach (Spinacia oleracea L.) plants grown in solution culture: effects of iodine species and solution concentrations.

    PubMed

    Zhu, Y-G; Huang, Y-Z; Hu, Y; Liu, Y-X

    2003-04-01

    A hydroponic experiment was carried out to investigate the effects of iodine species and solution concentrations on iodine uptake by spinach (Spinacia oleracea L.). Five iodine concentrations (0, 1, 10, 50 and 100 microM) for iodate (IO(3)(-)) and iodide (I(-)) were used. Results show that higher concentrations of I(-) (> or =10 microM) had some detrimental effect on plant growth, while IO(3)(-) had little effect on the biomass production of spinach plants. Increases in iodine concentration in the growth solution significantly enhanced I concentrations in plant tissues. The detrimental effect of I(-) on plant growth was probably due to the excessively high accumulation of I in plant tissues. The solution-to-spinach leaf transfer factors (TF(leaf), fresh weight basis) for plants treated with iodide were between 14.2 and 20.7 at different solution concentrations of iodide; TF(leaf) for plants treated with iodate decreased gradually from 23.7 to 2.2 with increasing solution concentrations of iodate. The distribution coefficients (DCs) of I between leaves and roots were constantly higher for plants treated with iodate than those treated with iodide. DCs for plants treated with iodide increased with increasing solution concentrations of iodide, while DCs for plants treated with iodate (around 5.5) were similar across the range of solution concentrations of iodate used in this experiment. The implications of iodine accumulation in leafy vegetables in human iodine nutrition are also discussed. PMID:12605934

  5. Sucrose and Starch Synthesis in Spinach Plants Grown under Long and Short Photosynthetic Periods

    PubMed Central

    Baysdorfer, Chris; Robinson, J. Michael

    1985-01-01

    The flow of carbon into sucrose and starch was investigated in fully expanded primary leaves of spinach using the long to short day transition and partial defoliation as tools to manipulate sucrose/starch synthesis. Transfer from 12 hour to 7 hour photosynthetic periods resulted in a 4-fold increase in the initial rate of starch synthesis, a 50% increase in the initial rate of sucrose synthesis, a 30% increase in leaf sucrose, and a 40% decrease in fructose, 2,6-biphosphate. In addition, sucrose synthesis rates in cells isolated from shortened daylength plants are 80% higher than in cells isolated from control plants. These results show that, in spinach, an increase in the rates of both sucrose and starch synthesis can occur under short day conditions. In contrast, when short day plants are partially defoliated, starch levels remain high, fructose 2,6-biphosphate levels remain low, but the level of leaf sucrose drops by 50%. Thus, when demand exceeds supply, starch synthesis has priority over filling of leaf sucrose pools in the short day plant. PMID:16664501

  6. Toxicity effects of olive-mill wastewater on growth, photosynthesis and pollen morphology of spinach plants.

    PubMed

    Asfi, Maria; Ouzounidou, Georgia; Panajiotidis, Sampson; Therios, Ioannis; Moustakas, Michael

    2012-06-01

    Olive mill-wastewater (OMW), a by-product of the olive oil extraction process, represents a significant environmental problem in Mediterranean areas. We studied the impact of OMW dilutions (1:10 and 1:20) on growth, photosynthesis, proline and sugar accumulation as well as on pollen morphology of spinach (Spinacia oleracea L.) plants, to evaluate the application of OMW dilutions as pretreatment technique, prior to land disposal. Biomass, height, total chlorophyll and leaf area of spinach declined progressively with decreasing OMW dilution. Since fatty acids and phenolic compounds (present in the OMW) are considered precursors in the polymerization of sporopollenin, we suggest that under OMW treatment spinach plants seem to 'direct' the excess of these substances in the production and formation of increased pollen grains. Proline did not accumulate under OMW stress, but decreased possible due to transport to pollens in response to increased demand to over-production of pollens. Both OMW dilutions resulted in a decreased efficiency of PSII functioning and an increased excitation pressure (1-q(p)). It is concluded that, higher than 1:20 OMW dilutions should be used, and/or additional treatment should be applied before use of the OMW in the environment. PMID:22455663

  7. Rapid detection of Salmonella typhimurium on fresh spinach leaves using phage-immobilized magnetoelastic biosensors

    NASA Astrophysics Data System (ADS)

    Horikawa, Shin; Li, Suiqiong; Chai, Yating; Park, Mi-Kyung; Shen, Wen; Barbaree, James M.; Vodyanoy, Vitaly J.; Chin, Bryan A.

    2011-06-01

    This paper presents an investigation into the use of magnetoelastic biosensors for the rapid detection of Salmonella typhimurium on fresh spinach leaves. The biosensors used in this investigation were comprised of a strip-shaped, goldcoated sensor platform (2 mm-long) diced from a ferromagnetic, amorphous alloy and a filamentous fd-tet phage which specifically binds with S. typhimurium. After surface blocking with bovine serum albumin, these biosensors were, without any preceding sample preparation, directly placed on wet spinach leaves inoculated with various concentrations of S. typhimurium. Upon contact with cells, the phage binds S. typhimurium to the sensor thereby increasing the total mass of the sensor. This change in mass causes a corresponding decrease in the sensor's resonant frequency. After 25 min, the sensors were collected from the leaf surface and measurements of the resonant frequency were performed immediately. The total assay time was less than 30 min. The frequency changes for measurement sensors (i.e., phageimmobilized) were found to be statistically different from those for control sensors (sensors without phage), down to 5 × 106 cells/ml. The detection limit may be improved by using smaller, micron-sized sensors that will have a higher probability of contacting Salmonella on the rough surfaces of spinach leaves.

  8. 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

  9. Applied studies of the plant meridian system: II. Agri-wave technology increases the yield and quality of spinach and lettuce and enhances the disease resistant properties of spinach.

    PubMed

    Hou, T Z; Mooneyham, R E

    1999-01-01

    Agri-wave technology is composed of both a special frequency sound wave and a microelement fertilizer. In both components, the effect of sound waves on plants is more than that of fertilizers, but the best function is a combination of the two. Treatment by Agri-wave technology stimulated the growth rate and increased the yield of spinach. In small plot tests, the length and width of the treated spinach leaf was 50.8 cm and 20.3 cm, respectively, whereas the untreated leaves were 29.20 cm and 8.9 cm. The fresh weight of treated spinach was 0.42 kg. This was 5.5 times higher than that of the untreated spinach. In large area testing (17 hectares), the results of two tests show that the yields of the treated spinach were increased 22.7% and 22.2% over those of the control group. Sugar content of the treated spinach was increased by 37.5%, vitamin A, C, and B were increased 35.63%, 41.67% and 40.00%, respectively, above the levels of the control group. Niacin content was decreased by 7.69%. Of 33 elements analyzed in the spinach, 29 elements were increased by Agri-wave technology. The spinach was infected with "rot disease" in the control group while there was no disease present in the treated group. In greenhouse testing, the average weight of 3 species of lettuce treated by Agri-wave technology was increased 44.10% over that of the control group (P < 0.0001). The average weight of 3 species of lettuce by only sound and only fertilizer treated separately increased 29.92% and 16.19% above that of the control group (P < 0.0001). Sampling survey results in the field test were comparable to the above mentioned greenhouse test. The fresh weight of treated lettuce by Agri-wave technology was increased 41.67% over that of the control group (P < 0.0001). The fresh weight of treated lettuce by only sound and only fertilizer was increased 30.88% and 19.61%, respectively, over the control group (both P < 0.0001). PMID:10467447

  10. [Nitrates in canned spinach. Effects of technological treatments].

    PubMed

    Sohier, Y; Poumarat, A M; Berges, P

    1976-01-01

    During the last twenty years, the nitrate content of spinach has regularly increased along with the use of nitragenous fertilizers. A study made in the center of Britain (France) shows that along with this growing nitrate content, the quantity of raw harvested spinach has practically doubled in twenty years. But for the same quantity of raw harvested spinach, the yield of canned spinach has noticeably lowered. In a cannery trials made to lower the nitrate levels (preheating, blanching, renewing water blanching) led to a loss of about 45% of nitrate (on a dry matter basis). However nitrate levels stay about the same in one kg of raw spinach and in one kg of processed spinach coming from the same batch. The only answer seems to be able and come from better agricultural practices. PMID:1030213

  11. Responses of Ribulose-1,5-Bisphosphate Carboxylase, Cytochrome f, and Sucrose Synthesis Enzymes in Rice Leaves to Leaf Nitrogen and Their Relationships to Photosynthesis.

    PubMed Central

    Makino, A.; Nakano, H.; Mae, T.

    1994-01-01

    The photosynthetic gas-exchange rates and various biochemical components of photosynthesis, including ribulose-1,5-bisphosphate carboxylase (Rubisco) content, cytochrome (Cyt) f content, and the activities of two sucrose synthesis enzymes, were examined in young, fully expanded leaves of rice (Oryza sativa L.) grown hydroponically in different nitrogen concentrations. The light-saturated rate of photosynthesis at an intercellular CO2 pressure of 20 Pa (CO2-limited photosynthesis) was linearly dependent on leaf nitrogen content, but curvilinearly correlated with Rubisco content. This difference was due to a greater than proportional increase in Rubisco content relative to leaf nitrogen content and the presence of a CO2 transfer resistance between the intercellular air spaces and the carboxylation sites. CO2-limited photosynthesis was proportional to Cyt f content, one of the key components of electron transport, but was not proportional to the activities of cytosolic fructose-1,6-bisphosphatase and sucrose phosphate synthase, the two regulatory enzymes of sucrose synthesis. Light-saturated photosynthesis above an intercellular CO2 pressure of 60 Pa (CO2-saturated photosynthesis) was curvilinearly dependent on leaf nitrogen content. This CO2-saturated photosynthesis was proportional to Cyt f content in the low- and normal-nitrogen leaves, and correlated better with the activities of cytosolic fructose-1,6-bisphosphatase and sucrose phosphate synthase in the high-nitrogen leaves. The increase in the activities of these two enzymes with increasing leaf nitrogen was not as great as the increase in Cyt f content. Thus, as leaf nitrogen increased, the limitation caused by the activities of sucrose synthesis enzymes came into play, which resulted in the curvilinear relationship. However, this limitation by sucrose synthesis enzymes did not affect photosynthesis under normal ambient air. PMID:12232197

  12. 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

  13. 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

    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

  14. 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...

  15. 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...

  16. 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...

  17. Effect of route of introduction and host cultivar on the colonization, internalization, and movement of the human pathogen Escherichia coli O157:H7 in spinach.

    PubMed

    Mitra, R; Cuesta-Alonso, E; Wayadande, A; Talley, J; Gilliland, S; Fletcher, J

    2009-07-01

    Human pathogens can contaminate leafy produce in the field by various routes. We hypothesized that interactions between Escherichia coli O157:H7 and spinach are influenced by the route of introduction and the leaf microenvironment. E. coli O157:H7 labeled with green fluorescent protein was dropped onto spinach leaf surfaces, simulating bacteria-laden raindrops or sprinkler irrigation, and survived on the phylloplane for at least 14 days, with increasing titers and areas of colonization over time. The same strains placed into the rhizosphere by soil infiltration remained detectable on very few plants and in low numbers (10(2) to 10(6) CFU/g fresh tissue) that decreased over time. Stem puncture inoculations, simulating natural wounding, rarely resulted in colonization or multiplication. Bacteria forced into the leaf interior survived for at least 14 days in intercellular spaces but did not translocate or multiply. Three spinach cultivars with different leaf surface morphologies were compared for colonization by E. coli O157:H7 introduced by leaf drop or soil drench. After 2 weeks, cv. Bordeaux hosted very few bacteria. More bacteria were seen on cv. Space and were dispersed over an area of up to 0.3 mm2. The highest bacterial numbers were observed on cv. Tyee but were dispersed only up to 0.15 mm2, suggesting that cv. Tyee may provide protected niches or more nutrients or may promote stronger bacterial adherence. These findings suggest that the spinach phylloplane is a supportive niche for E. coli O157:H7, but no conclusive evidence was found for natural entry into the plant interior. The results are relevant for interventions aimed at minimizing produce contamination by human pathogens. PMID:19681281

  18. End-Product Control of Carbon Metabolism in Culture-Grown Sugar Beet Plants (Molecular and Physiological Evidence on Accelerated Leaf Development and Enhanced Gene Expression).

    PubMed Central

    Kovtun, Y.; Daie, J.

    1995-01-01

    Sugar beet (Beta vulgaris L.) seedlings were grown on media containing 90 to 300 mM sucrose or glucose. Compared to controls, sugar-grown plants had higher growth rate, photosynthesis, and leaf sugar levels. The steady-state level of transcripts increased significantly for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) (rbcS) and the cytosolic fructose-1,6-bisphosphatase and moderately for the Rubisco large subunit (rbcL). The transcript level of sucrose phosphate synthase remained unchanged. Fructose-1,6-bisphosphatase and Rubisco activities did not change in the presence of sugars, but that of sucrose phosphate synthase increased (44 and 90% under selective and nonselective assay conditions, respectively). Accelerated leaf development was indicated by (a) autoradiograms of leaves that showed that sucrose loading occurred earlier, (b) export capacity that also occurred earlier but, after about 2 weeks, differences were not detectable, and (c) sucrose synthase activity that declined significantly. Several conclusions emerged: (a) response was nonosmotic and gene and sugar specific, (b) sugars caused accelerated leaf development and sink-to-source transition, (c) enhanced gene expression was due to advanced leaf development, and (d) whereas Rubisco and cytosolic fructose-1,6-bisphosphatase genes were sugar repressed in mature leaves of greenhouse-grown plants, they were unaffected in mature, culture-grown leaves. To our knowledge, these data provide the first evidence in higher plants that, depending on the physiological/developmental context of leaves, sugars lead to differential regulation of the same gene. PMID:12228569

  19. Impact of pigeon pea biochar on cadmium mobility in soil and transfer rate to leafy vegetable spinach.

    PubMed

    Coumar, M Vassanda; Parihar, R S; Dwivedi, A K; Saha, J K; Rajendiran, S; Dotaniya, M L; Kundu, S

    2016-01-01

    Introduction of heavy metals in the environment by various anthropogenic activities has become a potential treat to life. Among the heavy metals, cadmium (Cd) shows relatively high soil mobility and has high phyto-mammalian toxicity. Integration of soil remediation and ecosystem services, such as carbon sequestration in soils through organic amendments, may provide an attractive land management option for contaminated sites. The application of biochar in agriculture has recently received much attention globally due to its associated multiple benefits, particularly, long-term carbon storage in soil. However, the application of biochar from softwood crop residue for heavy metal immobilization, as an alternative to direct field application, has not received much attention. Hence, a pot experiment was conducted to study the effect of pigeon pea biochar on cadmium mobility in a soil-plant system in cadmium-spiked sandy loam soil. The biochar was prepared from pigeon pea stalk through a slow pyrolysis method at 300 °C. The experiment was designed with three levels of Cd (0, 5, and 10 mg Cd kg(-1) soil) and three levels of biochar (0, 2.5, and 5 g kg(-1) soil) using spinach as a test crop. The results indicate that with increasing levels of applied cadmium at 5 and 10 mg kg(-1) soil, the dry matter yield (DMY) of spinach leaf decreased by 9.84 and 18.29 %, respectively. However, application of biochar (at 2.5 and 5 g kg(-1) soil) significantly increased the dry matter yield of spinach leaf by 5.07 and 15.02 %, respectively, and root by 14.0 and 24.0 %, respectively, over the control. Organic carbon content in the post-harvest soil increased to 34.9 and 60.5 % due to the application of biochar 2.5 and 5 g kg(-1) soil, respectively. Further, there was a reduction in the diethylene triamine pentaacetic acid (DTPA)-extractable cadmium in the soil and in transfer coefficient values (soil to plant), as well as its concentrations in spinach leaf and root, indicating that cadmium mobility was decreased due to biochar application. This study shows that pigeon pea biochar has the potential to increase spinach yield and reduce cadmium mobility in contaminated sandy soil. PMID:26670040

  20. Pressurized liquid extraction of flavonoids from spinach.

    PubMed

    Howard, L; Pandjaitan, N

    2008-04-01

    Pressurized liquid extraction (PLE) using water and a 70:30 mixture of ethanol and water over the temperature range of 50 to 190 degrees C was used to extract flavonoids from dried spinach. The total phenolic content, antioxidant capacity, color, and browning indices of the extracts were also evaluated. PLE using a 70:30 mixture of ethanol and water was more effective than water in extracting flavonoids from spinach. Flavonoids were effectively extracted over the temperature band of 50 to 130 degrees C with water and 50 to 150 degrees C with ethanolic solvent. Levels of total phenolics and ORAC values increased with increasing extraction temperature, indicating that flavonoids were minor contributors to antioxidant capacity at elevated extraction temperatures. Browning of ethanolic extracts correlated highly with ORAC values over the temperature range of 50 to 190 degrees C, and the ORAC values of the large molecular weight fraction (> 1000 Da) increased linearly over the temperature range, indicating that Maillard polymers were the major contributors to antioxidant capacity. The results illustrate that PLE temperatures of < 130 degrees C for water or < 150 degrees C for ethanolic solvent may be used to extract flavonoids, followed by a high temperature (> 170 degrees C) extraction to generate antioxidant-rich moieties. PMID:18387092

  1. Choline Oxidation by Intact Spinach Chloroplasts 1

    PubMed Central

    Weigel, Pierre; Lerma, Claudia; Hanson, Andrew D.

    1988-01-01

    Plants synthesize betaine by a two-step oxidation of choline (choline ? betaine aldehyde ? betaine). Protoplast-derived chloroplasts of spinach (Spinacia oleracea L.) carry out both reactions, more rapidly in light than in darkness (AD Hanson et al. 1985 Proc Natl Acad Sci USA 82: 3678-3682). We investigated the light-stimulated oxidation of choline, using spinach chloroplasts isolated directly from leaves. The rates of choline oxidation obtained (dark and light rates: 10-50 and 100-300 nanomoles per hour per milligram chlorophyll, respectively) were approximately 20-fold higher than for protoplast-derived chloroplasts. Betaine aldehyde was the main product. Choline oxidation in darkness and light was suppressed by hypoxia. Neither uncouplers nor the Calvin cycle inhibitor glyceraldehyde greatly affected choline oxidation in the light, and maximal choline oxidation was attained far below light saturation of CO2 fixation. The light stimulation of choline oxidation was abolished by the PSII inhibitors DCMU and dibromothymoquinone, and was partially restored by adding reduced diaminodurene, an electron donor to PSI. Both methyl viologen and phenazine methosulfate prevented choline oxidation. Adding dihydroxyacetone phosphate, which can generate NADPH in organello, doubled the dark rate of choline oxidation. These results indicate that choline oxidation in chloroplasts requires oxygen, and reducing power generated from PSI. Enzymic reactions consistent with these requirements are discussed. Images Fig. 1 PMID:16665893

  2. 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

  3. Microtubules in mesophyll cells of nonacclimated and cold-acclimated spinach : visualization and responses to freezing, low temperature, and dehydration.

    PubMed

    Bartolo, M E; Carter, J V

    1991-09-01

    Responses of cortical microtubules in spinach (Spinacia oleracea L. cv Bloomsdale) mesophyll cells to freezing, thawing, supercooling, and dehydration were assessed. Microtubules were visualized using a modified procedure for indirect immunofluorescence microscopy. Leaf sections of nonacclimated and cold-acclimated spinach were slowly frozen to various temperatures, fixed while frozen, and microtubules immunolabelled. Both nonacclimated and cold-acclimated cells exhibited nearly complete microtubule depolymerization after ice formation. After 1 hour thawing at 23 degrees C, microtubules in both nonacclimated and cold-acclimated cells repolymerized. With time, however, microtubules in nonacclimated cells again depolymerized. Since microtubules in cells of leaf tissue frozen slowly are subjected to dehydration as well as subzero temperatures, these stresses were applied separately and their effects on microtubules noted. Supercooling induced microtubule depolymerization in both nonacclimated and cold-acclimated cells, but to a smaller extent than did freezing. Exposing leaf sections to solutions of sorbitol (a cell wall-penetrating osmoticum) or polyethylene glycol 10,000 (a nonpenetrating osmoticum) at room temperature caused microtubule depolymerization. The effects of low temperature and dehydration are roughly additive in producing the observed microtubule responses during freezing. Only small differences in microtubule stability were resolved between nonacclimated and cold-acclimated cells. PMID:16668366

  4. 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.

  5. Salt treatment induces frost hardiness in leaves and isolated thylakoids from spinach.

    PubMed

    Schmidt, J E; Schmitt, J M; Kaiser, W M; Hincha, D K

    1986-05-01

    Frost hardiness of spinach (Spinacia oleracea L.) leaves was increased by high concentrations of NaCl in the hydroponic culture medium. Freezing damage was determined by measurement of slow chlorophyll fluorescence quenching after freezing of leaves. Both the osmolality of the leaf sap and forst hardiness of the leaves were linearly correlated with the salt concentration in the hydroponic culture medium. Freezing damage occurred, irrespective of the extent of frost hardening, when dehydration of cells during extracellular ice formation decreased cellular volume to approximately 14% of the volume of unfrozen cells. The resistance of isolated, washed thylakoids against mechanical and chemical damage by freezing was investigated. Chemical damage by freezing caused by salt accumulation was measured as release of chloroplast coupling factor (CF1; EC 3.6.1.3), and mechanical damage was measured as release of the lumenal protein plastocyanin from the membranes during an in-vitro freeze-thaw cycle. Isolated thylakoids from salt-treated frost-hardy spinach and those from plants hardened under natural conditions did not exhibit improved tolerance against chemical freezing stress exerted by high salt concentrations. They were, however, more hardy than thylakoids from unhardened control leaves against mechanical damage by freezing. PMID:24233734

  6. 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 α-diversity (t test, P<0.05), indicating a putative competition between the pathogen and indigenous spinach microbes. The decrease in the β-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

  7. Thermal inactivation kinetics of hepatitis A virus in spinach.

    PubMed

    Bozkurt, Hayriye; Ye, Xiaofei; Harte, Federico; D'Souza, Doris H; Davidson, P Michael

    2015-01-16

    Leafy vegetables have been recognized as important vehicles for the transmission of foodborne viral pathogens. To control hepatitis A viral foodborne illness outbreaks associated with mildly heated (e.g., blanched) leafy vegetables such as spinach, generation of adequate thermal processes is important both for consumers and the food industry. Therefore, the objectives of this study were to determine the thermal inactivation behavior of hepatitis A virus (HAV) in spinach, and provide insights on HAV inactivation in spinach for future studies and industrial applications. The D-values calculated from the first-order model (50-72 C) ranged from 34.40 4.08 to 0.91 0.12 min with a z-value of 13.92 0.87 C. The calculated activation energy value was 162 11 kJ/mol. Using the information generated in the present study and the thermal parameters of industrial blanching conditions for spinach as a basis (100 C for 120-180 s), the blanching of spinach in water at 100 C for 120-180 s under atmospheric conditions will provide greater than 6 log reduction of HAV. The results of this study may be useful to the frozen food industry in designing blanching conditions for spinach to inactivate or control hepatitis A virus outbreaks. PMID:25462934

  8. 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

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

    SciTech Connect

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

    1988-01-01

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

  10. Effect of Greens and Soil Type, Sulfur Addition and Lithium Level on Leaf Constituents

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A greenhouse experiment was conducted near Weslaco, Texas (Lat. 26o 8' N, Long. 97o 57' W) between Dec. 2006 and Feb 2007 to evaluate the effect of soil type, added sulfur and lithium level on the growth and leaf nutrients, particularly biofortified levels of Li and S, in spinach and mustard gree...

  11. 3-Ketoacyl-acyl carrier protein synthase III from spinach (Spinacia oleracea) is not similar to other condensing enzymes of fatty acid synthase.

    PubMed Central

    Tai, H; Jaworski, J G

    1993-01-01

    A cDNA clone encoding spinach (Spinacia oleracea) 3-ketoacyl-acyl carrier protein synthase III (KAS III), which catalyzes the initial condensing reaction in fatty acid biosynthesis, was isolated. Based on the amino acid sequence of tryptic digests of purified spinach KAS III, degenerate polymerase chain reaction (PCR) primers were designed and used to amplify a 612-bp fragment from first-strand cDNA of spinach leaf RNA. A root cDNA library was probed with the PCR fragment, and a 1920-bp clone was isolated. Its deduced amino acid sequence matched the sequences of the tryptic digests obtained from the purified KAS III. Northern analysis confirmed that it was expressed in both leaf and root. The clone contained a 1218-bp open reading frame coding for 405 amino acids. The identity of the clone was confirmed by expression in Escherichia coli BL 21 as a glutathione S-transferase fusion protein. The deduced amino acid sequence was 48 and 45% identical with the putative KAS III of Porphyra umbilicalis and KAS III of E. coli, respectively. It also had a strong local homology to the plant chalcone synthases but had little homology with other KAS isoforms from plants, bacteria, or animals. PMID:8290632

  12. 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

  13. Greenhouse spinach production in a NFT system.

    PubMed

    Both, A J; Leed, A R; Goto, E; Albright, L D; Langhans, R W

    1996-12-01

    Primed spinach (Spinacia oleracea L., cv. Nordic) seed was started in rockwool slabs in a growth room for eight days before the seedlings were transplanted into a controlled environment greenhouse equipped with five identical, but separate, NFT systems. The day and night temperatures in the greenhouse were maintained at 24 and 18 degrees C, respectively, with the daytime starting at 06:00 and ending at 22:00 hr. A photoperiod of 16 hrs was maintained, to prevent early bolting, and different target daily integrated light levels (PPF, in mol m-2 d-1) were studied to observe dry weight production. HPS lamps were used as the supplemental light source. Thirty-three days after seeding a final harvest was performed. Using the expolinear growth equation, dry weight production can be predicted based solely on target daily integrated light levels. Total chlorine residuals in the nutrient solution higher than 1 ppm were observed to be toxic. Root disease (rot) in the plant crown was found to be caused by Fusarium. Several remedies, including three biofungicides and potassium silicate, were tried but none proved to be consistently successful. PMID:11541569

  14. 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...

  15. Light intensity is the main factor affecting fresh market spinach tolerance for Phenmedipham

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The few available herbicides for fresh market spinach do not provide adequate weed control, and there is need for additional herbicide tools. Phenmedipham is registered for use in processing spinach but not in fresh spinach due to its crop injury potential and short time window from application to h...

  16. First report of Beet necrotic yellow vein virus infecting spinach in California.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2009, plants from two spinach (Spinacia oleracea) experimental fields in Monterey County and one commercial spinach field in Ventura County of California exhibited vein clearing, mottling, interveinal yellowing and stunting symptoms. For experimental fields, up to 44% of spinach plants were infec...

  17. Identification of Six Endogenous Gibberellins in Spinach Shoots 1

    PubMed Central

    Metzger, James D.; Zeevaart, Jan A. D.

    1980-01-01

    Analysis of highly purified extracts from spinach shoots by combined gas chromatography-mass spectrometry has demonstrated the presence of six 13-C-hydroxylated gibberellins (GAs): GA53, GA44, GA19, GA17, GA20, and GA29. The major GAs were GA17, GA19, and GA20, whereas the other three GAs occurred in trace amounts. Structural considerations suggest that the six GAs identified in spinach are related in the following metabolic sequence: GA53 → GA44 → GA19 → GA17 → GA20 → GA29. PMID:16661251

  18. Design, Synthesis, and Application of Spinach Molecular Beacons Triggered by Strand Displacement

    PubMed Central

    Bhadra, Sanchita; Ellington, Andrew D.

    2015-01-01

    We describe design parameters for the synthesis and analytical application of a label-free RNA molecular beacon, termed Spinach.ST. The RNA aptamer Spinach fluoresces upon binding the small-molecule fluorophore DFHBI ((Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one). Spinach has been reengineered by extending its 5′- and 3′-ends to create Spinach.ST, which is predicted to fold into an inactive conformation that fails to bind DHFBI. Hybridization of a trigger oligonucleotide to a designed toehold on Spinach.ST initiates toehold-mediated strand displacement and restores the DFHBI-binding, fluorescence-enhancing conformation of Spinach. The versatile Spinach.ST sensor can detect DNA or RNA trigger sequences and can readily distinguish single-nucleotide mismatches in the trigger toehold. Primer design techniques are described that augment amplicons produced by enzymatic amplification with Spinach.ST triggers. Interaction between these triggers and Spinach.ST molecular beacons leads to the real-time, sequence-specific quantitation of these amplicons. The use of Spinach.ST with isothermal amplification reactions such as nucleic acid sequence-based amplification (NASBA) may enable point-of-care applications. The same design principles could also be used to adapt Spinach reporters to the assay of nonnucleic acid analytes in trans. PMID:25605388

  19. Design, synthesis, and application of Spinach molecular beacons triggered by strand displacement.

    PubMed

    Bhadra, Sanchita; Ellington, Andrew D

    2015-01-01

    We describe design parameters for the synthesis and analytical application of a label-free RNA molecular beacon, termed Spinach.ST. The RNA aptamer Spinach fluoresces upon binding the small-molecule fluorophore DFHBI ((Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one). Spinach has been reengineered by extending its 5'- and 3'-ends to create Spinach.ST, which is predicted to fold into an inactive conformation that fails to bind DHFBI. Hybridization of a trigger oligonucleotide to a designed toehold on Spinach.ST initiates toehold-mediated strand displacement and restores the DFHBI-binding, fluorescence-enhancing conformation of Spinach. The versatile Spinach.ST sensor can detect DNA or RNA trigger sequences and can readily distinguish single-nucleotide mismatches in the trigger toehold. Primer design techniques are described that augment amplicons produced by enzymatic amplification with Spinach.ST triggers. Interaction between these triggers and Spinach.ST molecular beacons leads to the real-time, sequence-specific quantitation of these amplicons. The use of Spinach.ST with isothermal amplification reactions such as nucleic acid sequence-based amplification (NASBA) may enable point-of-care applications. The same design principles could also be used to adapt Spinach reporters to the assay of nonnucleic acid analytes in trans. PMID:25605388

  20. 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. )

    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.

  1. Role of Ascorbate in Detoxifying Ozone in the Apoplast of Spinach (Spinacia oleracea L.) Leaves.

    PubMed Central

    Luwe, MWF.; Takahama, U.; Heber, U.

    1993-01-01

    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-1 of ozone resulted in ozone uptake by the leaves close to 0.9 pmol cm-2 of leaf surface area s-1. Apoplastic AA was slowly oxidized by ozone. The initial decrease of apoplastic AA was <0.1 pmol cm-2 s-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. The data show that 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-2 s-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 glutathi-one 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-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. PMID:12231749

  2. Biosynthesis of Sucrose and Mannitol as a Function of Leaf Age in Celery (Apium graveolens L.) 1

    PubMed Central

    Davis, Jeanine M.; Fellman, John K.; Loescher, Wayne H.

    1988-01-01

    In celery (Apium graveolens L.), the two major translocated carbohydrates are sucrose and the acyclic polyol mannitol. Their metabolism, however, is different and their specific functions are uncertain. To compare their roles in carbon partitioning and sink-source transitions, developmental changes in 14CO2 labeling, pool sizes, and key enzyme activities in leaf tissues were examined. The proportion of label in mannitol increased dramatically with leaf maturation whereas that in sucrose remained fairly constant. Mannitol content, however, was high in all leaves and sucrose content increased as leaves developed. Activities of mannose-6-P reductase, cytoplasmic and chloroplastic fructose-1,6-bisphosphatases, sucrose phosphate synthase, and sucrose synthase increased with leaf maturation and decreased as leaves senesced. Ribulose bisphosphate carboxylase and nonreversible glyceraldehyde-3-P dehydrogenase activities rose as leaves developed but did not decrease. Thus, sucrose is produced in all photosynthetically active leaves whereas mannitol is synthesized primarily in mature leaves and stored in all leaves. Onset of sucrose export in celery may result from sucrose accumulation in expanding leaves, but mannitol export is clearly unrelated to mannitol concentration. Mannitol export, however, appears to coincide with increased mannitol biosynthesis. Although mannitol and sucrose arise from a common precursor in celery, subsequent metabolism and transport must be regulated separately. PMID:16665852

  3. Far-Red Light-Induced Changes in Intracellular Potentials of Spinach Mesophyll Cells

    PubMed Central

    Montavon, Michel; Horwitz, Benjamin A.; Greppin, Hubert

    1983-01-01

    In green plants, the large bioelectric changes that photosynthetically active light stimulates make it difficult to observe electrical potential changes related to phytochrome photoconversion. As a first step towards distinguishing between photosynthetic and phytochrome effects, we showed that red light enhances far-red stimulated intracellular potential changes in spinach (Spinacia oleracea) leaf mesophyll cells. For a dark-adapted leaf, the response to far-red light increased during the first 10 to 30 exposures of 2.5 minutes, after which it was constant. The intracellular potential depolarized by an average of 0.3 millivolts during each 2.5-minute far-red light period, and returned to the resting value during each subsequent dark period. Continuous supplementary red light (at 1-5% of the fluence rate of the far-red light that stimulated the depolarizations) increased the response to far-red 2- to 3-fold. Supplementary red light did not amplify the response to alternating 702 nanometers light and dark periods. The Emerson enhancement effect thus does not seem to explain amplification of the response to 730 nanometers light by supplementary red light. This does not prove that photosynthetic pigments are not involved in some other way. PMID:16663280

  4. The aggregation states of spinach phosphoribulokinase.

    PubMed

    Porter, M A

    1990-06-01

    Phosphoribulokinase (PRK; EC 2.1.7.19) is active in illuminated chloroplasts and inactive in darkened chloroplasts. This regulatory mechanism is mediated by thioredoxin-dependent reduction of a kinase disulfide in vivo. Extracts of spinach (Spinacia oleracea L.) leaves in the presence of 10 mM dithiothreitol contain a single 80-kDa form of PRK as judged by gel filtration. Gel filtration of thiol-free extracts of light-harvested tissue shows the presence of two inactive forms of PRK, the 80-kDa form and an aggregate (> 550 kDa) form, but treatment of both forms with dithiothreitol restores kinase activity. Gel filtration following extraction of dark-harvested tissue in the absence of dithiotreitol demonstrates the presence of only the heavier form. Inclusion of 400 mM (NH4)2SO4 in the homogenization buffer during extraction of light-harvested tissue suppresses the formation of the high-M r form of PRK, but does not eliminate the aggregate form observed in extracts of dark-harvested leaves. However, prolonged treatment of extracts from dark-harvested tissue with 400 mM (NH4)2SO4 results in conversion of the high-M r form of phosphoribulokinase to the low-M r form. The data are consistent with the heavier form of phosphoribulokinase being the normal in-vivo aggregation state in the dark, while the lighter form is the normal aggregation state in the light.This research was sponsored jointly by the science and education administration of the U.S. Department of Agriculture under Grant No. 88-37130-3722 from the Competitive Research Grants Office and by the Office of Health and Environmental Research, U.S. Department of Energy under Contract DE-AC05-84OR21400 with Martin Marietta Energy Systems Inc., Oak Ridge, Tenn., USA. The author is Postdoctoral Investigator supported by the U.S. Department of Agriculture through Subcontract No. 88-37130-3722 from the Biology Division of Oak Ridge National Laboratory to the University of Tennessee. PMID:24196813

  5. First report of Tobacco rattle virus in spinach in California.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2009 in coastal California (Santa Barbara County), commercially grown spinach (Spinacia oleracea) in two nearby fields exhibited symptoms of a previously unrecognized virus-like disease. Symptoms consisted of general chlorosis and bright yellow blotches and spots. Necrotic spots were also associa...

  6. Isolation and Characterization of Phosphatidyl Choline from Spinach Leaves.

    ERIC Educational Resources Information Center

    Devor, Kenneth A.

    1979-01-01

    This inexpensive but informative experiment for undergraduate biochemistry students involves isolating phosphatidyl choline from spinach leaves. Emphasis is on introducing students to techniques of lipid extraction, separation of lipids, identification using thin layer chromatography, and identification of fatty acids. Three periods of three hours…

  7. Survival of pathogenic Escherichia coli on basil, lettuce, and spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The contamination of lettuce, spinach and basil with pathogenic E. coli has caused numerous illnesses over the past decade. E. coli O157:H7, E. coli O104:H4 and avian pathogenic E. coli (APECstx- and APECstx+) were inoculated on basil plants and in promix soiless substrate using drip and overhead ir...

  8. Isolation and Characterization of Phosphatidyl Choline from Spinach Leaves.

    ERIC Educational Resources Information Center

    Devor, Kenneth A.

    1979-01-01

    This inexpensive but informative experiment for undergraduate biochemistry students involves isolating phosphatidyl choline from spinach leaves. Emphasis is on introducing students to techniques of lipid extraction, separation of lipids, identification using thin layer chromatography, and identification of fatty acids. Three periods of three hours

  9. Freezing Injury and Resistance in Spinach Chloroplast Grana 12

    PubMed Central

    Williams, Robert J.; Meryman, H. T.

    1970-01-01

    Spinach grana appear to be injured by the same mechanism and by the same degree of dehydration and volume reduction that injures animal cells. Winter-hardened or artificially protected grana avoid injury by permitting a reversible influx of solute which forestalls excessive dehydration and shrinkage. PMID:16657386

  10. 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

  11. 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.

  12. Expression and purification of spinach nitrite reductase in E. coli

    SciTech Connect

    Bellissimo, D.; Privalle, L. )

    1991-03-11

    The study of structure-function relationships in nitrite reductase (NiR) by site-directed mutagenesis requires an expression system from which suitable quantities of active enzyme can be purified. Spinach NiR cDNA was cloned into pUC18 and expressed in E.coli JM109 as a beta-galactosidase fusion protein. The IPTG-induced fusion protein contains five additional amino acids at the N-terminus. The expressed NiR in aerobic cultures was mostly insoluble and inactive indicating the presence of inclusion bodies. By altering growth conditions, active NiR could represent 0.5-1.0% of the total E.coli protein, Effects of the addition of delta-aminolevulinic acid, a heme precursor, and anaerobic growth were also examined. Spinach NiR was purified approximately 200 fold to homogeneity. When subjected to electrophoresis on SDS polyacrylamide gels, the NiR migrated as a single band with similar mobility to pure spinach enzyme. The expressed enzyme also reacted with rabbit anti-spinach NiR antibody as visualized by Western blot analysis. The absorption spectrum of the E.coli-expressed enzyme was identical to spinach enzyme with a Soret and alpha band a 386 and 573 nm, respectively, and an A{sub 278}/A{sub 386} = 1.9. The addition of nitrite produced the characteristic shifts in the spectrum. The E. coli-expressed NiR catalyzed the methylviologen-dependent reduction of nitrite. The specific activity was 100 U/mg. The K{sub m} determined for nitrite was 0.3 mM which is in agreement with values reported for the enzyme. These results indicate that the E.coli-expressed NiR is fully comparable to spinach NiR in purity, catalytic activity and physical state. Site-directed mutants have been made using PCR to examine structure-function relationships in this enzyme.

  13. Role of Cellulose and Colanic Acid in Attachment of Shiga Toxin-Producing Escherichia coli to Lettuce and Spinach in Different Water Hardness Environments.

    PubMed

    Lee, Chi-Ching; Chen, Jinru; Frank, Joseph F

    2015-08-01

    This study investigated the role of extracellular cellulose production by Shiga toxin-producing Escherichia coli (STEC) on attachment to lettuce and spinach in different water hardness environments. Two cellulose-producing wild-type STEC strains, 19 (O5:H-) and 49 (O103:H2), and their cellulose-deficient derivatives were used. Strain 49 also produced colanic acid as a constituent of its extracellular polymeric substances. Attached cells were determined by plate counts on the surface and cut edge of the leaves after an attachment period of 2 h at 4C. Hydrophobicity and surface charge of the cells were determined. Strain 49 attached at levels 0.3 and 0.6 log greater to the surface and 0.9 and 0.4 log greater to the cut edges of spinach compared to strain 19 for both wild-type and cellulose-deficient cells (P > 0.05). Cellulose-producing cells attached more to the surface of lettuce but not of spinach than did cellulose-deficient cells. However, more cellulose-deficient cells attached (at levels 0.66 and 0.3 log greater) to the cut edge of lettuce (representing damaged tissue) than did cellulose-proficient cells (P > 0.05). Colanic acid production was associated with cell surfaces of low hydrophobicity. There was a decreasing level of attachment for the colanic acid-producing strain when water hardness increased from 200 to 1,000 pm on lettuce and spinach leaf surfaces, but no effects were seen for other cells. This decreased attachment was associated with a more negative surface charge. Cells that produced colanic acid were less hydrophobic and exhibited greater attachment to the surface and cut edge of spinach when compared to cells that did not produce colanic acid. Attachment of colanic acid-producing cells to leafy green surfaces was enhanced in higher water hardness environments. These data indicate that attachment of E. coli O157:H7 to leafy greens involves multiple mechanisms that are influenced by the type of leafy green, damage to the leaf, and the water hardness environment. PMID:26219358

  14. Sizes of Mn-binding sites in spinach thylakoids

    SciTech Connect

    Takahashi, M.; Asada, K.

    1986-12-25

    The sizes of the Mn-binding sites in spinach thylakoids were estimated by target size analysis, assaying the membrane-bound Mn that was resistant to EDTA washing after radiation inactivation. The inactivation curve showed well the inactivation of two independent Mn-binding sites of different sizes: about two-thirds of the Mn coordinated to a binding site of 65 kDa, and the rest bound to a much smaller site of only about 3 kDa. In the large site, there was about 1 g atom of Mn/110 mol of chlorophyll in spinach thylakoids, which was constant in normally grown plants, although the Mn level in the small site depended on culture conditions. Thylakoids that had been incubated with hydroxylamine or in 0.8 M Tris lost Mn exclusively from the large binding site.

  15. Evidence for lipid kinase activities in spinach chloroplast envelope membranes.

    PubMed

    Siegenthaler, P A; Müller, M O; Bovet, L

    1997-10-13

    Three spinach chloroplast envelope membrane preparations (i.e. whole, outer and inner membranes) were incubated in the presence of [gamma-32P]ATP. After lipid extraction and separation by TLC, four main phosphorylated lipids were detected by autoradiography in whole envelope preparations. These phospholipids were identified by comparing their Rf with that of lipid markers and by a deacylation procedure. They were found to be phosphatidic acid (PA) and lyso-PA, L-alpha-phosphatidyl-inositol 4-monophosphate (PIP) and lyso-PIP. These lipids were not equally distributed in the outer and inner envelope membranes. Chloroplast envelope membranes were verified not to be contaminated by plasma membranes. It is concluded that lipid kinase activities are associated with spinach chloroplast envelope membranes. PMID:9369232

  16. Photosynthate partitioning during flowering in relation to senescence of spinach

    SciTech Connect

    Sklensky, D.; Davies, P.J. )

    1990-05-01

    Male spinach plants are frequently cited as a counter-example to the nutrient drain hypothesis. Photosynthate partitioning in both male and female plants was examined. Leaves just below the inflorescences in plants at various stages of flowering were labelled with {sup 14}CO{sub 2} and the photosynthate allowed to partition for three hours. The leaves, flowers and stems of the inflorescence, and the other above ground vegetative tissue were harvested. These parts were combusted in a sample oxidizer for the collection of the {sup 14}CO{sub 2}. Allocation to the male and female flowers at very early stages are similar. As the flowers develop further, male flowers receive more photosynthate than do female flowers in early fruit production. Thus it is possible that nutrient drain to the flowers in male spinach plants is sufficient to account for senescence.

  17. Microbiological Quality of Bagged Cut Spinach and Lettuce Mixes?

    PubMed Central

    Valentin-Bon, Iris; Jacobson, Andrew; Monday, Steven R.; Feng, Peter C. H.

    2008-01-01

    Analysis of 100 bagged lettuce and spinach samples showed mean total bacterial counts of 7.0 log10 CFU/g and a broad range of <4 to 8.3 log10 CFU/g. Most probable numbers (MPN) of ?11,000 /g coliforms were found in 55 samples, and generic Escherichia coli bacteria were detected in 16 samples, but no E. coli count exceeded 10 MPN/g. PMID:18156327

  18. Studies of GA sub 53 oxidase from spinach

    SciTech Connect

    Wilson, T.; Zeevaart, J.A.D. )

    1990-05-01

    GA{sub 53} oxidase was purified 1,750-fold with 1% recovery of activity from spinach after exposure to 8 long days. This preparation was injected into balb/c mice and hybridomas from spleen cells were produced. Upon preliminary screening by immunoprecipitation of enzyme activity, three positive cell lines were selected. These are being cloned to select a true monoclonal antibody cell line. This antibody will be used to study the light/dark regulation of this enzyme.

  19. Desaturation of oleoyl groups in envelope membranes from spinach chloroplasts.

    PubMed Central

    Schmidt, H; Heinz, E

    1990-01-01

    Envelope membranes isolated from chloroplasts of spinach (Spinacia oleracea) desaturate oleoyl groups in monogalactosyl diacylglycerol to linoleoyl groups. The desaturation requires NADPH in combination with ferredoxin and is not restricted to monogalactosyl diacylglycerol, since it is also observed in biosynthetic intermediates as, for example, in phosphatidic acid. This indicates a certain degree of unspecificity of the oleate desaturase in isolated envelope membranes. Lipid desaturation is another important function of chloroplast envelopes. PMID:11607123

  20. Enzyme-assisted extraction of stabilized chlorophyll from spinach.

    PubMed

    Özkan, Gülay; Ersus Bilek, Seda

    2015-06-01

    Zinc complex formation with chlorophyll derivatives in spinach pulp was studied by adding 300ppm Zn(2+) for production of stable food colorant, followed by the heating at 110°C for 15min. Zinc complex formation increased at pH values of 7.0 or greater. Pectinex Ultra SP-L was selected for enzyme-assisted release of zinc-chlorophyll derivatives from spinach pulp. Effect of enzyme concentration (1-9%), treatment temperature (30-60°C), and time (30-210min) on total chlorophyll content (TCC) were optimized using response surface methodology. A quadratic regression model (R(2)=0.9486) was obtained from the experimental design. Optimum treatment conditions were 8% enzyme concentration, 45°C, and 30min, which yielded a 50.747mgTCC/100g spinach pulp. Enzymatic treatment was followed by solvent extraction with ethanol at a solvent-to-sample ratio of 2.5:1 at 60°C for 45min for the highest TCC recovery. Pretreatment with enzyme and extraction in ethanol resulted in 39% increase in Zn-chlorophyll derivative yield. PMID:25624218

  1. Comparative uptake of enteric viruses into spinach and green onions.

    PubMed

    Hirneisen, Kirsten A; Kniel, Kalmia E

    2013-03-01

    Root uptake of enteric pathogens and subsequent internalization has been a produce safety concern and is being investigated as a potential route of pre-harvest contamination. The objective of this study was to determine the ability of hepatitis A virus (HAV) and the human norovirus surrogate, murine norovirus (MNV), to internalize in spinach and green onions through root uptake in both soil and hydroponic systems. HAV or MNV was inoculated into soil matrices or into two hydroponic systems, floating and nutrient film technique systems. Viruses present within spinach and green onions were detected by RT-qPCR or infectivity assays after inactivating externally present viruses with Virkon(). HAV and MNV were not detected in green onion plants grown up to 20days and HAV was detected in only 1 of 64 spinach plants grown in contaminated soil substrate systems up to 20days. Compared to soil systems, a drastic difference in virus internalization was observed in hydroponic systems; HAV or pressure-treated HAV and MNV were internalized up to 4 logRT-qPCR units and internalized MNV was shown to remain infectious. Understanding the interactions of human enteric viruses on produce can aid in the elucidation of the mechanisms of attachment and internalization, and aid in understanding risks associated with contamination events. PMID:23412715

  2. 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.

  3. Effect of Photoperiod on the Metabolism of Deuterium-Labeled Gibberellin A53 in Spinach 1

    PubMed Central

    Gianfagna, Thomas; Zeevaart, Jan A. D.; Lusk, William J.

    1983-01-01

    Application of gibberellin A53 (GA53) to short-day (SD)-grown spinach (Spinacia oleracea L.) plants caused an increase in petiole length and leaf angle similar to that found in plants transferred to long days (LD). [2H] GA53 was fed to plants in SD, LD, and in a SD to LD transition experiment, and the metabolites were identified by gas chromatography with selected ion monitoring. After 2, 4, or 6 SD, [2H]GA53 was converted to [2H]GA19 and [2H]GA44. No other metabolites were detected. After 2 LD, only [2H] GA20 was identified. In the transition experiment in which plants were given 4 SD followed by 2 LD, all three metabolites were found. The results demonstrate unequivocally that GA19, GA20, and GA44 are metabolic products of GA53, and strongly suggest that photoperiod regulates GA metabolism, in part, by controlling the conversion of GA19 to GA20. PMID:16662988

  4. Spinach downy mildew: overview of races and the development of molecular markers linked to major resistance genes.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spinach (Spinacia aleracea) has become an increasingly popular leafy vegetable crop, particularly in the United States. Recent trends have shown a substantial increase in per capita fresh market spinach consumption with a corresponding increase in production. As a result, spinach production practic...

  5. Differences in biofilm formation of produce and poultry Salmonella enterica isolates and their persistence on spinach plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Repeat irrigation of spinach plants with water containing Salmonella was used to determine Salmonella persistence on spinach leaves. Spinach plants were irrigated four times (biweekly) with water containing ca. 2.1 log CFU Salmonella per 100 ml water (the maximum generic E. coli MPN recommended by...

  6. Spinach: A new natural host of Impatiens necrotic spot virus in California.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Impatiens necrotic spot tospovirus (INSV; family Bunyaviridae) was detected in a spinach (Spinacia oleracea) experimental field in Monterey County, CA in October of 2008. Spinach plants exhibiting severe stunting and with leaves that showed interveinal yellowing, thickening, and deformation were obs...

  7. 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...

  8. 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...

  9. Changes in quality, liking and purchase intent of irradiated fresh-cut spinach during storage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of ionizing radiation to enhance microbial safety of fresh spinach at a maximum dose of 4 kGy has been approved by the U.S. Food and Drug Administration. However, whether spinach can tolerate those high doses of radiation is unclear. Therefore, this study was conducted to investigate effect...

  10. Biodegradable PLA (polylactic acid) hinged trays keep quality of fresh-cut and cooked spinach.

    PubMed

    Botondi, Rinaldo; Bartoloni, Serena; Baccelloni, Simone; Mencarelli, Fabio

    2015-09-01

    This work examines the effects of packaging using two different polymeric trays with hinged lids, polyethylene terephthalate (PET) and polylactic acid (PLA), on fresh-cut and cooked spinach (Spinacia oleracea). Samples were stored in a cold room for 16 days at 4 °C. Chemical (total pigments, total polyphenols, ascorbic acid, antioxidant activity), physical (water activity), technological (colour evaluation), sensorial (aroma, visual appearance and water accumulation) and microbial (total aerobic mesophilic and psychrotrophic counts) parameters were tested. Both polymeric trays maintained the overall quality of fresh spinach for 6 days but spinach stored in PLA trays maintained its flavour longer. A significant increase in total polyphenols, antiradical activity, total carotenoids as well as a decrease in ascorbic acid in fresh spinach was observed in the first 3 days of storage in both samples. Unfortunately, the PLA package accumulated condensed water. The total microbial load of fresh-cut spinach reached about 6.3-7.3 log CFU g(-1) within 8 days. Cooked spinach packed in PLA and PET polymeric hinged trays showed the same behaviour as fresh spinach in terms of quality and shelf life. In conclusion, PLA plastic hinged trays can be used for packaging fresh-cut and cooked cut spinach, but the problem of condensed water must be solved. PMID:26345011

  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. 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 ...

  13. 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...

  14. 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

  15. Survival of pathogenic Escherichia coli on basil, lettuce, and spinach.

    PubMed

    Markland, S M; Shortlidge, K L; Hoover, D G; Yaron, S; Patel, J; Singh, A; Sharma, M; Kniel, K E

    2013-12-01

    The contamination of lettuce, spinach and basil with pathogenic E. coli has caused numerous illnesses over the past decade. E. coli O157:H7, E. coli O104:H4 and avian pathogenic E. coli (APECstx- and APECstx+) were inoculated on basil plants and in promix substrate using drip and overhead irrigation. When overhead inoculated with 7 log CFU/ml of each strain, E. coli populations were significantly (P = 0.03) higher on overhead-irrigated plants than on drip-irrigated plants. APECstx-, E. coli O104:H4 and APECstx+ populations were recovered on plants at 3.6, 2.3 and 3.1 log CFU/g at 10 dpi (days post-inoculation), respectively. E. coli O157:H7 was not detected on basil after 4 dpi. The persistence of E. coli O157:H7 and APECstx- were similar when co-inoculated on lettuce and spinach plants. On spinach and lettuce, E. coli O157:H7 and APEC populations declined from 5.7 to 6.1 log CFU/g and 4.5 log CFU/g, to undetectable at 3 dpi and 0.6-1.6 log CFU/g at 7 dpi, respectively. The detection of low populations of APEC and E. coli O104:H4 strains 10 dpi indicates these strains may be more adapted to environmental conditions than E. coli O157:H7. This is the first reported study of E. coli O104:H4 on a produce commodity. PMID:23280331

  16. Bioavailability of soluble oxalate from spinach eaten with and without milk products.

    PubMed

    Brogren, Madelene; Savage, Geoffrey P

    2003-01-01

    Leafy vegetables such as spinach (Spinacia oleracea) are known to contain moderate amounts of soluble and insoluble oxalates. Frozen commercially available spinach in New Zealand contains 736.6+/-20.4 mg/100g wet matter (WM) soluble oxalate and 220.1+/-96.5mg/100g WM insoluble oxalate. The frozen spinach contained 90mg total calcium/100g WM, 76.7%of this calcium was unavailable as it was bound to oxalate as insoluble oxalate. The oxalate/calcium (mEq) ratio of the frozen spinach was 4.73. When frozen convenience food is grilled there is no opportunity for the soluble oxalates to be leached out into the cooking water and discarded. Soluble oxalates, when consumed, have the ability to bind to calcium in the spinach and any calcium in foods consumed with the spinach, reducing the absorption of soluble oxalate. In this experiment 10 volunteers ingested 100g grilled spinach alone or with 100g additions of cottage cheese, sour cream and sour cream with Calci-Trim milk (180 g) and finally, with 20g olive oil. The availability of oxalate in the spinach was determined by measuring the oxalate output in the urine over a 6-hour and 24-hour period after intake of the test meal. The mean bioavailability of soluble oxalate in the grilled spinach was 0.75+/-0.48% over a 6-hour period after intake and was 1.93+/-0.85% measured over a 24-hour period. Addition of sour cream and Calci-Trim milk reduced the availability of the oxalate in the spinach significantly (P<0.05) in both the 6-hour and 24-hour collection periods. PMID:12810415

  17. 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...

  18. Pathway for the synthesis of triacylglycerols from monogalactosyldiacylglycerols in ozone-fumigated spinach leaves. [Spinacia oleracea L

    SciTech Connect

    Sakaki, Takeshi; Kondo, Noriaki; Yamada, Mitsuhiro Univ. of Tokyo )

    1990-10-01

    When the upper leaf surface of spinach (Spinacia oleracea L.) plants was treated with (1-{sup 14}C)acetate and grown for 2 days, {sup 14}C was effectively incorporated into acyl moieties of leaf lipids in ratios approximately their composition by mass. Fumigation of the plants with ozone (0.5 microliter per liter) caused a redistribution of {sup 14}C among lipid classes, i.e. a marked increase of {sup 14}C content in triacylglycerol (TG) and 1,2-diacylglycerol (1,2-DG) and a decrease of label in monogalactosyldiacylglycerol (MGDG) without affecting {sup 14}C distribution in leaf fatty acids. Label in both TG and 1,2-DG was found predominantly in their polyene molecular species. Since MGDG consists of similar polyene molecular species, the results indicate the synthesis of TG from MGDG via 1,2-DG. Label was also accumulated in tri- and tetragalactosyldiacylglycerol, products of galactolipid:galactolipid galactosyltransferase (GGGT). Moreover, there was a close relation between increases in the amounts of TG and the oligogalactolipids in ozone-treated leaves. These results indicate that MGDG was converted to 1,2-DG by GGGT and then to TG. In intact chloroplasts isolated from ozone-treated leaves, there was an enhanced production of free fatty acid (FFA), which was diminished by the addition of coenzyme A (CoA) and ATP, indicating that ozone stimulated the hydrolysis of MGDG to liberate FFA, which was in turn converted to acyl-CoA. The final step of TG synthesis, acylation of 1,2-DG with acyl-CoA, was confirmed by feeding with (1-{sup 14}C)linolenic acid in leaf discs excised from ozone-fumigated leaves; {sup 14}C was effectively incorporated into TG but not into 1,2-DG.

  19. Insect molting hormone and sterol biosynthesis in spinach

    SciTech Connect

    Grebenok, R.J.; Adler, J.H. )

    1990-05-01

    Insect molting hormones, which are produced by plants and are effective molecules in the control of insect crop pests, are biosynthesized in developing spinach leaves (Spinacia oleracea L.). The major sterols biosynthesized by spinach are avenasterol (24{alpha}-ethyl-5{alpha}-cholesta-7,24(28)-dien-3{beta}-ol), spinasterol (24{alpha}-ethyl-5{alpha}-cholesta-7,22-dien-3{beta}-ol), and 22-dihydrospinasterol (24{alpha}-ethyl-5{alpha}-cholest-7-en-3{beta}-ol). The major ecdysteroids biosynthesized are ecdysterone (2{beta},3{beta},14{alpha},20R,22R,25-hexahydroxy-5{beta}-cholest-7-en-6-one) and polypodine B (2{beta},3{beta},5{beta},14{alpha},20R,22R,25-heptahycroxycholest-7-en-6-one) and polypodine B (2{beta},3{beta},5{beta},14{alpha},20R,22R,25-heptahydroxycholest-7-en-6-one). When labeled 2-{sup 14}C-mevalonic acid was incorporated into young leaves isolated squalene, sterols and ecdysteroids contained the label. During a short (16 h) incorporation period in intact young leaves of 100 day old plants, the avenasterol has the highest specific activity in counts per minute per {mu}g of sterol followed by 22-dihydrospinasterol which is more highly labeled than spinasterol. The ecdysteroids synthesized, on an entire plant basis, account for 20% of the total steroid (sterol and ecdysteroid) isolated from the plant.

  20. Effect of photoperiod on gibberellin biosynthetic enzymes in spinach

    SciTech Connect

    Gilmour, S.J.; Bleecker, A.B.; Zeevaart, J.A.D.

    1986-04-01

    The photoperiodic control of stem elongation in spinach, a long day (LD) rosette plant, is mediated by gibberellins (GAs). The early 13-hydroxylated GA biosynthetic pathway from GA/sub 12/ to GA/sub 20/ operates in spinach: GA/sub 12/ ..-->.. GA/sub 53/ ..-->.. GA/sub 44/ ..-->.. GA/sub 19/ ..-->.. GA/sub 20/. Two enzymes of this pathway, those converting GA/sub 53/ to GA/sub 44/ (GA/sub 53/ oxidase) and GA/sub 19/ to GA/sub 20/ (GA/sub 19/ oxidase), are regulated by light. The enzyme converting GA/sub 44/ to GA/sub 19/ (GA/sub 44/ oxidase) is not light-regulated. In the light GA/sub 53/ and GA/sub 18/ oxidase activities are increased, therefore causing the GA biosynthetic pathway to be turned on. This leads to the production of an active GA in LD, which causes an increase in stem elongation. Two the enzymes, GA/sub 44/ and GA/sub 53/ oxidases, can be separated from one another by anion exchange HPLC. Estimates of the molecular weights of these two enzymes based on gel filtration HPLC will be reported.

  1. Choline oxidation by intact spinach chloroplasts. [Spinacia oleracea L

    SciTech Connect

    Weigel, P.; Lerma, C.; Hanson, A.D.

    1988-01-01

    Plants synthesize betaine by a two-step oxidation of choline (choline ..-->.. betaine aldehyde ..-->.. betaine). Protoplast-derived chloroplasts of spinach (Spinacia oleracea L.) carry out both reactions, more rapidly in light than in darkness. We investigated the light-stimulated oxidation of choline, using spinach chloroplasts isolated directly from leaves. The rates of choline oxidation obtained (dark and light rates: 10-50 and 100-300 nanomoles per hour per milligram chlorophyll, respectively) were approximately 20-fold higher than for protoplast-derived chloroplasts. Betaine aldehyde was the main product. Choline oxidation in darkness and light was suppressed by hypoxia. Neither uncouplers not the Calvin cycle inhibitor glyceraldehyde greatly affected choline oxidation in the light, and maximal choline oxidation was attained far below light saturation of CO/sub 2/ fixation. The light stimulation of choline oxidation was abolished by the PSII inhibitors DCMU and dibromothymoquinone, and was partially restored by adding reduced diaminodurene, an electron donor to PSI. Both methyl viologen and phenazine methosulfate prevented choline oxidation. Adding dihydroxyacetone phosphate, which can generate NADPH in organello, doubled the dark rate of choline oxidation. These results indicate that choline oxidation in chloroplasts requires oxygen, and reducing power generated from PSI. Enzymic reactions consistent with these requirements are discussed.

  2. Assay, Purification, and Partial Characterization of Choline Monooxygenase from Spinach.

    PubMed

    Burnet, M.; Lafontaine, P. J.; Hanson, A. D.

    1995-06-01

    The osmoprotectant glycine betaine is synthesized via the path-way choline -> betaine aldehyde -> glycine betaine. In spinach (Spinacia oleracea), the first step is catalyzed by choline monooxygenase (CMO), and the second is catalyzed by betaine aldehyde dehydrogenase. Because betaine aldehyde is unstable and not easily detected, we developed a coupled radiometric assay for CMO. [14C]Choline is used as substrate; NAD+ and betaine aldehyde dehydrogenase prepared from Escherichia coli are added to oxidize [14C]betaine aldehyde to [14C]glycine betaine, which is isolated by ion exchange. The assay was used in the purification of CMO from leaves of salinized spinach. The 10-step procedure included polyethylene glycol precipitation, polyethyleneimine precipitation, hydrophobic interaction, anion exchange on choline-Sepharose, dimethyldiethanolamine-Sepharose, and Mono Q, hydroxyapatite, gel filtration, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Following gel filtration, overall purification was about 600-fold and recovery of activity was 0.5%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a polypeptide with a molecular mass of 45 kD. Taken with the value of 98 kD estimated for native CMO (R. Brouquisse, P. Weigel, D. Rhodes, C.F. Yocum, A.D. Hanson [1989] Plant Physiol 90: 322-329), this indicates that CMO is a homodimer. CMO preparations were red-brown, showed absorption maxima at 329 and 459 nm, and lost color upon dithionite addition, suggesting that CMO is an iron-sulfur protein. PMID:12228495

  3. Leaf Carbohydrate Status and Enzymes of Translocate Synthesis in Fruiting and Vegetative Plants of Cucumis sativus L. 1

    PubMed Central

    Pharr, David M.; Huber, Steven C.; Sox, Harriet N.

    1985-01-01

    Carbon partitioning in the leaves of Cucumis sativus L., a stachyose translocating plant, was influenced by the presence or absence of a single growing fruit on the plant. Fruit growth was very rapid with rates of fresh weight gain as high as 3.3 grams per hour. Fruit growth was highly competitive with vegetative growth as indicated by lower fresh weights of leaf blades, petioles, stem internodes and root systems on plants bearing a single growing fruit compared to plants not bearing a fruit. Carbon exchange rates, starch accumulation rates and carbon export rates were higher in leaves of plants bearing a fruit. Dry weight loss from leaves was higher at night from fruiting plants, and morning starch levels were consistently lower in leaves of fruiting than in leaves of vegetative plants indicating rapid starch mobilization at night from the leaves of fruiting plants. Galactinol, the galactosyl donor for stachyose biosynthesis, was present in the leaves of fruit-bearing plants at consistently lower concentration than in leaves of vegetative plants. Galactinol synthase, and sucrose phosphate synthase activities were not different on a per gram fresh weight basis in leaves from the two plant types; however, stachyose synthase activity was twice as high in leaves from fruiting plants. Thus, the lower galactinol pools may be associated with an activation of the terminal step in stachyose biosynthesis in leaves in response to the high sink demand of a growing cucumber fruit. PMID:16663989

  4. Rapid cloning and bioinformatic analysis of spinach Y chromosome-specific EST sequences.

    PubMed

    Deng, Chuan-Liang; Zhang, Wei-Li; Cao, Ying; Wang, Shao-Jing; Li, Shu-Fen; Gao, Wu-Jun; Lu, Long-Dou

    2015-12-01

    The genome of spinach single chromosome complement is about 1000 Mbp, which is the model material to study the molecular mechanisms of plant sex differentiation. The cytological study showed that the biggest spinach chromosome (chromosome 1) was taken as spinach sex chromosome. It had three alleles of sex-related X,X(m) and Y. Many researchers have been trying to clone the sex-determining genes and investigated the molecular mechanism of spinach sex differentiation. However,there are no successful cloned reports about these genes. A new technology combining chromosome microdissection with hybridization-specific amplification (HSA) was adopted. The spinach Y chromosome degenerate oligonucleotide primed-PCR (DOP-PCR) products were hybridized with cDNA of the male spinach flowers in florescence. The female spinach genome was taken as blocker and cDNA library specifically expressed in Y chromosome was constructed. Moreover, expressed sequence tag (EST) sequences in cDNA library were cloned, sequenced and bioinformatics was analysed. There were 63 valid EST sequences obtained in this study. The fragment size was between 53 and 486 bp. BLASTn homologous alignment indicated that 12 EST sequences had homologous sequences of nucleic acids, the rest were new sequences. BLASTx homologous alignment indicated that 16 EST sequences had homologous protein-encoding nucleic acid sequence. The spinach Y chromosome-specific EST sequences laid the foundation for cloning the functional genes, specifically expressed in spinach Y chromosome. Meanwhile, the establishment of the technology system in the research provided a reference for rapid cloning of other biological sex chromosome-specific EST sequences. PMID:26690526

  5. 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

  6. 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

  7. The Simultaneous Determination of Carbon Dioxide Release and Oxygen Uptake in Suspensions of Plant Leaf Mitochondria Oxidizing Glycine 1

    PubMed Central

    Lilley, Ross McC.; Ebbighausen, Holger; Heldt, Hans W.

    1987-01-01

    The construction and operation of a device for continuous measurement of CO2 release by suspensions of respiring mitochondria is described. A combination of this device with a Clark-type O2 electrode was used for simultaneous measurement of respiration and of CO2 release by spinach and pea leaf mitochondria with glycine as substrate. Both mitochondrial preparations showed high rates of respiration and high respiratory control ratios. The addition of oxaloacetate not only inhibited O2 uptake substantially, but also greatly stimulated glycine oxidation as monitored by CO2 release. In spinach leaf mitochondria, the maximal rates of glycine oxidation thus obtained, were two times higher than the rate of glycine oxidation required at average rates of photorespiration. It is concluded from these results that under saturating conditions the capacity of glycine oxidation by intact mitochondria exceeds the capacity of glycine-dependent respiration. PMID:16665248

  8. Suppression Effects of Betaine-Enriched Spinach on Hyperhomocysteinemia Induced by Guanidinoacetic Acid and Choline Deficiency in Rats

    PubMed Central

    Liu, Yi-Qun; Jia, Zheng; Han, Feng; Inakuma, Takahiro; Miyashita, Tatsuya; Sugiyama, Kimio; Sun, Li-Cui; Xiang, Xue-Song; Huang, Zhen-Wu

    2014-01-01

    Betaine is an important natural component of rich food sources, especially spinach. Rats were fed diets with betaine or spinach powder at the same level of betaine for 10 days to investigate the dose-dependent effects of spinach powder supplementation on hyperhomocysteinemia induced by guanidinoacetic acid (GAA) addition and choline deprivation. The GAA-induced hyperhomocysteinemia in rats fed 25% casein diet (25C) was significantly suppressed by supplementation with betaine or spinach, and it was completely suppressed by taking 11.0% spinach supplementation. The choline deprivation-induced enhancement of plasma homocysteine concentration in rats fed 25% soybean protein diet (25S) was markedly suppressed by 3.82% spinach. Supplementation with betaine or spinach partially prevented the effects of GAA on hepatic concentrations of methionine metabolites. The decrease in activity of betaine-homocysteine S-methyltransferase (BHMT) and cystathionine ?-synthase (CBS) in GAA-induced hyperhomocysteinemia was recovered by supplementation with betaine or spinach. Supplementation with betaine or spinach did not affect BHMT activity, whereas it partially restored CBS activity in choline-deprived 25S. The results indicated that betaine or spinach could completely suppress the hyperhomocysteinemia induced by choline deficiency resulting from stimulating the homocysteine removal by both remethylation and cystathionine formation. PMID:25250392

  9. Suppression effects of betaine-enriched spinach on hyperhomocysteinemia induced by guanidinoacetic acid and choline deficiency in rats.

    PubMed

    Liu, Yi-Qun; Jia, Zheng; Han, Feng; Inakuma, Takahiro; Miyashita, Tatsuya; Sugiyama, Kimio; Sun, Li-Cui; Xiang, Xue-Song; Huang, Zhen-Wu

    2014-01-01

    Betaine is an important natural component of rich food sources, especially spinach. Rats were fed diets with betaine or spinach powder at the same level of betaine for 10 days to investigate the dose-dependent effects of spinach powder supplementation on hyperhomocysteinemia induced by guanidinoacetic acid (GAA) addition and choline deprivation. The GAA-induced hyperhomocysteinemia in rats fed 25% casein diet (25 C) was significantly suppressed by supplementation with betaine or spinach, and it was completely suppressed by taking 11.0% spinach supplementation. The choline deprivation-induced enhancement of plasma homocysteine concentration in rats fed 25% soybean protein diet (25S) was markedly suppressed by 3.82% spinach. Supplementation with betaine or spinach partially prevented the effects of GAA on hepatic concentrations of methionine metabolites. The decrease in activity of betaine-homocysteine S-methyltransferase (BHMT) and cystathionine ?-synthase (CBS) in GAA-induced hyperhomocysteinemia was recovered by supplementation with betaine or spinach. Supplementation with betaine or spinach did not affect BHMT activity, whereas it partially restored CBS activity in choline-deprived 25S. The results indicated that betaine or spinach could completely suppress the hyperhomocysteinemia induced by choline deficiency resulting from stimulating the homocysteine removal by both remethylation and cystathionine formation. PMID:25250392

  10. Purification and characterization of ribulose-5-phosphate kinase from spinach

    SciTech Connect

    Porter, M.A.; Milanez, S.; Stringer, C.D.; Hartman, F.C.

    1986-02-15

    An efficient purification procedure utilizing affinity chromatography is described for spinach ribulose-5-phosphate kinase, a light-regulated chloroplastic enzyme. Gel filtration and polyacrylamide gel electrophoresis of the purified enzyme reveal a dimeric structure of 44,000 Mr subunits. Chemical crosslinking with dimethyl suberimidate confirms the presence of two subunits per molecule of native kinase, which are shown to be identical by partial NH2-terminal sequencing. Based on sulfhydryl titrations and on amino acid analyses, each subunit contains four to five cysteinyl residues. The observed slow loss of activity during spontaneous oxidation in air-saturated buffer correlates with the intramolecular oxidation of two sulfhydryl groups, presumably those involved in thioredoxin-mediated regulation.

  11. Properties of Glucosyltransferase and Glucan Transferase from Spinach

    PubMed Central

    Linden, James C.; Tanner, Widmar; Kandler, Otto

    1974-01-01

    A glucosyl and a glucosyl-glucan transferase activity from spinach (Spinacia oleracea L. var. Matador) leaves have been partially purified and characterized. The latter activity (fraction 1 after diethylaminoethylcellulose chromatography) is responsible for the transfer of glucosyl as well as of maltosyl, maltotriosyl, and higher homologous residues to glucose giving rise to maltose and the correspondingly larger molecules. This fraction also shows ?-amylase activity. The transfer takes place only to glucose; maltose, as well as other ?-1,4-glucans, serve as donors. The enzyme fraction 2 is amylase-free and catalyzes only the transfer of glucosyl moieties, again with high acceptor specificity to glucose. Maltose and larger ?-1, 4-glucans, with the exception of maltotriose and maltotetraose, act as donors. The physiological function of these enzymes may be the formation of oligosaccharide primers for starch synthetase or phosphorylase. Images PMID:16658965

  12. A Mssbauer 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 Mssbauer 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.

  13. Solar energy from spinach and toothpaste: fabrication of a solar cell in schools

    NASA Astrophysics Data System (ADS)

    Siemsen, F.; Bunk, A.; Fischer, K.; Korneck, F.; Engel, H.; Roux, D.

    1998-01-01

    We will show how pupils can make a solar cell with spinach, toothpaste and a few other items found in any school laboratory. This device is called a Graetzel cell, and could trigger off a revolution in photovoltaic technology.

  14. Kinetic thermal degradation of vitamin C during microwave drying of okra and spinach.

    PubMed

    Dadali, Gke; Ozbek, Belma

    2009-01-01

    In this present study, the effect of microwave output power and sample amount on vitamin C loss in okra (Hibiscus esculenta L.) and spinach (Spinacia oleracea L.) were investigated using the microwave drying technique. The procedure is based on the reaction between l-ascorbic acid (vitamin C) and 2,6-dichloroindophenol. The proposed method was applied successfully to both okra and spinach for the determination of ascorbic acid (vitamin C) content. It was observed that as the microwave output power increased or as the sample amount decreased, the vitamin C in okra and spinach decreased as well. The activation energy for degradation of vitamin C for both okra and spinach was calculated using an exponential expression based on the Arrhenius equation. PMID:17886082

  15. 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.

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

    PubMed

    Rutzke, Corinne J; Glahn, Raymond P; Rutzke, Michael A; Welch, Ross M; Langhans, Robert W; Albright, Louis D; Combs, Gerald F; 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. PMID:15880905

  17. Uptake of different species of iodine by water spinach and its effect to growth.

    PubMed

    Weng, Huan-Xin; Yan, Ai-Lan; Hong, Chun-Lai; Xie, Lin-Li; Qin, Ya-Chao; Cheng, Charles Q

    2008-08-01

    A hydroponic experiment has been carried out to study the influence of iodine species [iodide (I(-)), iodate (IO(-)(3)), and iodoacetic acid (CH(2)ICOO(-))] and concentrations on iodine uptake by water spinach. Results show that low levels of iodine in the nutrient solution can effectively stimulate the growth of biomass of water spinach. When iodine levels in the nutrient solution are from 0 to 1.0 mg/l, increases in iodine levels can linearly augment iodine uptake rate by the leafy vegetables from all three species of iodine, and the uptake effects are in the following order: CH(2)ICOO(-) >I(-)>IO(-)(3). In addition, linear correlation was observed between iodine content in the roots and shoots of water spinach, and their proportion is 1:1. By uptake of I(-), vitamin C (Vit C) content in water spinach increased, whereas uptake of IO(-)(3) and CH(2)ICOO(-) decreased water spinach Vit C content. Furthermore, through uptake of I(-) and IO(-)(3). The nitrate content in water spinach was increased by different degrees. PMID:18449478

  18. Effect of spinach cultivar and bacterial adherence factors on survival of Escherichia coli O157:H7 on spinach leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Similarly to phytopathogens and epiphytic microorganisms, human bacterial pathogens have been shown to colonize on plant phylloplane. Along with environmental variables such as temperate, UV light, relative humidity, etc., plant cultivar and specifically the leaf blade morphological characteristics ...

  19. Inhibitory effect of monogalactosyldiacylglycerol, extracted from spinach using supercritical CO2, on mammalian DNA polymerase activity.

    PubMed

    Iijima, Hiroshi; Musumi, Keiichi; Hada, Takahiko; Maeda, Naoki; Yonezawa, Yuko; Yoshida, Hiromi; Mizushina, Yoshiyuki

    2006-03-01

    We investigated the effective extraction of monogalactosyldiacylglycerol (MGDG) from dried spinach (Spinacia oleracea) using supercritical fluid carbon dioxide (SC-CO(2)) with a modifier/entrainer. The yield of MGDG in the SC-CO(2) extract was not influenced by increasing temperature at a constant pressure, although the total extract yield was decreased. The total extract yield and MGDG yield in the extract from commercially purchased spinach (unknown subspecies), were greatly influenced by lower pressure. In a modifier (i.e., ethanol) concentration range of 2.5-20%, both the extract and MGDG yield increased as the ethanol concentration rose. The highest total extract yield (69.5 mg/g of spinach) and a good MGDG yield (16.3 mg/g of spinach) were obtained at 80 degrees C, 25 MPa, and 20% ethanol. The highest MGDG concentration (76.0% in the extract) was obtained at 80 degrees C, 25 MPa, and 2.5% ethanol, although the total extract yield under these conditions was low (5.2 mg/g of spinach). The optimal conditions for the extraction of MGDG were 80 degrees C, 20 MPa, and 10% ethanol. Of the 11 subspecies of spinach tested under these conditions, "Ujyou" had the highest concentration of MGDG. The total extract yield and MGDG concentration of Ujyou were 20.4 mg of the extract/g of spinach and 70.5%, respectively. The concentration of MGDG was higher in the SC-CO(2) extract than in the extract obtained using solvents such as methanol and n-hexane. The extract of Ujyou, which was the optimal subspecies for the extraction of MGDG, inhibited the activity of calf DNA polymerase alpha with IC(50) values of 145 microg/mL but was not effective against DNA polymerase beta. PMID:16506811

  20. Influence of variations in soil copper on the yield and nutrition of spinach grown in microplots on two organic soils

    SciTech Connect

    Mathur, S.P.; Belanger, A.; Sanderson, R.B.; Valk, M.; Knibbe, E.N.

    1984-01-01

    Spinach (Spinacia oleracea L. cv. Symphony) was grown in spring 1982 in field microplots of an organic soil (site I-mucky peat) containing 81 to 1063 ..mu..g Cu.g/sup -1/ soil, and cv. America of the same crop taken in summer 1982 on a peaty organic soil (site II) varying in Cu content from 13 to 1659 ..mu..g.g/sup -1/. The variations in soil Cu were mainly due to three rates of Cu applications in 1978 at site II and in 1979 at site I. At site I, the diversity in soil-Cu had no effect on yield or foliar-Cu levels in the crop. At site II soil-Cu was positively correlated with yield and foliar Cu; and negatively with leaf Fe due to a dilution effect. Neither soil Cu nor foliar Cu had any significant effect on Mo in leaves at both sites, except that the increase in yield due to the highest level of Cu at site II was accompanied by an increased plant uptake of Mo. Also, foliar Cu was positively correlated with P, Mg and Mn levels in leaves at site I; and foliar Ca, Mg and Mn at site II. Residual soil Cu up to 1063 ..mu..g.g/sup -1/ in a mucky peat and 1659 ..mu..g./sup -1/ in a peat showed no signs of causing phytotoxocity or significant nutritional imbalance. 19 references, 4 tables.

  1. Phosphoglycolate phosphatase of spinach acts as a phosphoenzyme

    SciTech Connect

    Rose, Z.B.; Seal, S.N.

    1987-05-01

    When /sup 32/P-glycolate and phosphoglycolate phosphatase from spinach are mixed, /sup 32/P is incorporated into acid precipitated protein. Properties that relate this phosphorylation to the enzyme are: The K/sub m/ value for P-glycolate is similar for protein phosphorylation and substrate hydrolysis; the /sup 32/P appearing in the phosphoenzyme is diluted by unlabeled P-glycolate or the alternative substrate, ethyl-P; the activator Cl/sup -/ enhances the effectiveness of ethyl-P as a substrate and as an inhibitor of the formation of /sup 32/P-enzyme; and /sup 32/P is lost from the enzyme when /sup 32/P-glycolate is consumed. The acid denatured phosphorylated protein is a molecule of 34,000 Da, which is half of the molecular weight of the native protein and is similar in size to the labeled band that is seen on SDS-polyacrylamide gels. The enzyme-bound phosphoryl group appears to be an acyl-phosphate from its pH stability, being quite stable at pH 1, less stable at pH 5, and very unstable above pH 5. The bond is readily hydrolyzed in acid molybdate and it is sensitive to cleavage by hydroxylamine at pH 6.8. The demonstration of enzyme phosphorylation by /sup 32/P-glycolate resolves the dilemma presented by initial rate studies in which alternative substrates appeared to have different mechanisms.

  2. Spinach pyruvate kinase isoforms: partial purification and regulatory properties

    SciTech Connect

    Baysdorfer, C.; Bassham, J.A.

    1984-02-01

    Pyruvate kinase from spinach (Spinacea oleracea L.) leaves consists of two isoforms, separable by blue agarose chromatography. Both isoforms share similar pH profiles and substrate and alternate nucleotide K/sub m/ values. In addition, both isoforms are inhibited by oxalate and ATP and activated by AMP. The isoforms differ in their response to three key metabolites; citrate, aspartate, and glutamate. The first isoform is similar to previously reported plant pyruvate kinases in its sensitivity to citrate inhibition. The K/sub i/ for this inhibition is 1.2 millimolar citrate. The second isoform is not affected by citrate but is regulated by aspartate and glutamate. Aspartate is an activator with a K/sub a/ of 0.05 millimolar, and glutamate is an inhibitor with a K/sub i/ of 0.68 millimolar. A pyruvate kinase with these properties has not been previously reported. Based on these considerations, the authors suggest that the activity of the first isoform is regulated by respiratory metabolism. The second isoform, in contrast, may be regulated by the demand for carbon skeletons for use in ammonia assimilation.

  3. Jumping mode atomic force microscopy on grana membranes from spinach.

    PubMed

    Sznee, Kinga; Dekker, Jan P; Dame, Remus T; van Roon, Henny; Wuite, Gijs J L; Frese, Raoul N

    2011-11-11

    The thylakoid membrane system is a complex membrane system that organizes and reorganizes itself to provide plants optimal chemical energy from sunlight under different and varying environmental conditions. Grana membranes are part of this system and contain the light-driven water-splitting enzyme Photosystem II (PSII) and light-harvesting antenna complexes. Here, we present a direct visualization of PSII complexes within grana membranes from spinach. By means of jumping mode atomic force microscopy in liquid, minimal forces were applied between the scanning tip and membrane or protein, allowing complexes to be imaged with high detail. We observed four different packing arrangements of PSII complexes, which occur primarily as dimers: co-linear crystalline rows, nanometric domains of straight or skewed rows, and disordered domains. Upon storing surface-adhered membranes at low temperature prior to imaging, large-scale reorganizations of supercomplexes between PSII and light-harvesting complex II could be induced. The highest resolution images show the existence of membrane domains without obvious topography extending beyond supercomplexes. These observations illustrate the possibility for diffusion of proteins and smaller molecules within these densely packed membranes. PMID:21911498

  4. Purification of gibberellin sub 53 -oxidase from spinach

    SciTech Connect

    Wilson, T.M.; Zeevaart, J.A.D. )

    1989-04-01

    Spinach is a long-day rosette plants, in which stem growth is mediated by gibberellins. It has been shown that two enzymatic steps, GA{sub 53}-oxidase and GA{sub 19}-oxidase, are controlled by light. To develop an understanding into this light regulation, purification of GA{sub 53}-oxidase has been undertaken. The original assay relied on the HPLC separation of the product and substrate, but was considered too slow for the development of a purification scheme. A TLC system was developed which in conjunction with improvements to the assay conditions was sensitive and gave rapid results. The partial purification of the GA{sub 53}-oxidase is achieved by a high speed centrifugation, 40-55% ammonium sulfate precipitation, an hydroxyapatite column, Sephadex G-100 column and an anion exchange FPLC column, Mono Q HR10/10, yielding 1000-fold purification and 15% recovery. Monoclonal antibodies to the protein will be raised and used to further characterize the enzyme.

  5. The Role of Galactolipids in Spinach Chloroplast Lamellar Membranes

    PubMed Central

    Anderson, Mark M.; McCarty, Richard E.; Zimmer, Elizabeth A.

    1974-01-01

    A galactolipid lipase has been isolated and partially purified from the chloroplast fraction of the primary leaves of Phaseolus vulgaris var. Kentucky Wonder. The lipase hydrolyzed monogalactosyl diglyceride rapidly and phosphatidyl choline relatively slowly. Triolein and p-nitrophenyl stearate were not hydrolyzed. Spinach subchloroplast particles were excellent substrates for the lipase. Initial rates of fatty acid release from subchloroplast particles at 30 C by the lipase as high as 60 microequivalents per minute per milligram protein were observed. At completion of the reaction, about 2.7 microequivalents of fatty acid were liberated per milligram of chlorophyll in the subchloroplast particles, indicating that major amounts of lipid in the particles were rapidly attacked by the lipase. The treatment of subchloroplast particles with the lipase resulted in a rapid inhibition of light-dependent electron flow. This inhibition was largely prevented when the incubation was carried out in the presence of high concentrations of defatted bovine serum albumin. These results suggest that when precautions are taken to prevent the binding of fatty acids to the subchloroplast particles, large amounts of lipid may be removed without a marked effect on electron flow. PMID:16658772

  6. Synthesis of Mono- and Digalactosyldiacylglycerol in Isolated Spinach Chloroplasts 1

    PubMed Central

    Heemskerk, Johan W. M.; Bögemann, Gerard; Helsper, Johannes P. F. G.; Wintermans, Jef F. G. M.

    1988-01-01

    Purified, intact chloroplasts of Spinacia oleracea L. synthesize galactose-labeled mono- and digalactosyldiacylglycerol (MGDG and DGDG) from UDP-[U-14C]galactose. In the presence of high concentrations of unchelated divalent cations they also synthesize tri- and tetra-galactosyldiacylglycerol. The acyl chains of galactose-labeled MGDG are strongly desaturated and such MGDG is a good precursor for DGDG and higher oligogalactolipids. The synthesis of MGDG is catalyzed by UDP-Gal:sn-1,2-diacylglycerol galactosyltransferase, and synthesis of DGDG and the oligogalactolipids is exclusively catalyzed by galactolipid:galactolipid galactosyltransferase. The content of diacylglycerol in chloroplasts remains low during UDP-Gal incorporation. This indicates that formation of diacylglycerol by galactolipid:galactolipid galactosyltransferase is balanced with diacylglycerol consumption by UDP-Gal:diacylglycerol galactosyltransferase for MGDG synthesis. Incubation of intact spinach chloroplasts with [2-14C]acetate or sn-[U-14C]glycerol-3-P in the presence of Mg2+ and unlabeled UDP-Gal resulted in high 14C incorporation into MGDG, while DGDG labeling was low. This de novo made MGDG is mainly oligoene. Its conversion into DGDG is also catalyzed, at least in part, by galactolipid:galactolipid galactosyltransferase. Images Fig. 1 PMID:16666019

  7. Changes in microbial populations on fresh cut spinach.

    PubMed

    Babic, I; Roy, S; Watada, A E; Wergin, W P

    1996-08-01

    The microbial populations found on fresh-cut spinach leaves that were stored in gas permeable bags at 10 degrees C for 12 days were examined and identified. The microorganisms consisted of mesophilic aerobic bacteria, psychrotrophic bacteria, Pseudomonadaceae, Enterobacteriaceae, Micrococcaceae, lactic acid bacteria and yeasts. Populations of mesophiles, psychrotrophs, Pseudomonadaceae and Enterobacteriaceae increased sharply during the storage period. The initial populations were 10(7), 10(6), 10(6) and 10(4) CFU.g-1 respectively. Populations reached 10(10) for the mesophiles, psychrotrophs and Pseudomonadaceae and 10(7) CFU.g-1 for Enterobacteriaceae after 12 days of storage. Micrococcaceae, lactic acid bacteria and yeasts remained constant (10(3)-10(4) CFU.g-1. The majority of the bacterial isolates were identified as Pseudomonas fluorescens, Aeromonas caviae and Staphylococcus xylosus. The yeasts, which were most frequently isolated, were classified in the genus Cryptococcus. No pathogens such as Listeria monocytogenes and Salmonella were detected. Observations with low temperature scanning electron microscopy (LTSEM) indicated that the microorganisms were not present on the surface of healthy unbroken leaves. Alternatively, they were found in areas where the cuticle was broken and could be seen infecting the internal palisade parenchyma. PMID:8880301

  8. Efficacy of chlorine and acidified sodium chlorite on microbial population and quality changes of spinach leaves.

    PubMed

    Nei, Daisuke; Choi, Ji-Weon; Bari, Md Latiful; Kawasaki, Susumu; Kawamoto, Shinichi; Inatsu, Yasuhiro

    2009-06-01

    Efficacy of washing with distilled water, chlorine solution, and acidified sodium chlorite (ASC) solution on populations of microorganisms on spinach leaves was evaluated. Washing with chlorine (100 mg/L) and ASC (sodium chlorite, 15 mg/L; citric acid, 200 mg/L) resulted in significant population reduction (1.1-1.9 log CFU/g) of aerobic microflora, coliform, and Escherichia coli O157:H7 (p < 0.05). There was no remarkable difference in decontamination efficacy between chlorine and ASC solution. In recent years, several sodium chlorite chemicals have been commercially available, and no difference in decontamination efficacy among the chemicals was observed when same concentration of sodium chlorite and citric acid were used. In addition, the reduction of E. coli O157:H7 population was influenced depending on the inoculation method and type of washing. It has been seen that dip-inoculated spinach leaves showed lower reduction than that of spot-inoculated spinach. After washing, populations of aerobic microflora, coliform, and E. coli O157:H7 were increased during storage at 10 degrees C, and washing condition before storage did not affect the subsequent increases in microbial population. Color of spinach leaves washed with ASC solution was not different from the color of those washed with water or chlorine solution, and washing with ASC solution was concluded to has no effect on appearance of spinach leaves. PMID:19422304

  9. Efficacy of chlorine and acidified sodium chlorite on microbial population and quality changes of spinach leaves.

    TOXLINE Toxicology Bibliographic Information

    Nei D; Choi JW; Bari ML; Kawasaki S; Kawamoto S; Inatsu Y

    2009-06-01

    Efficacy of washing with distilled water, chlorine solution, and acidified sodium chlorite (ASC) solution on populations of microorganisms on spinach leaves was evaluated. Washing with chlorine (100 mg/L) and ASC (sodium chlorite, 15 mg/L; citric acid, 200 mg/L) resulted in significant population reduction (1.1-1.9 log CFU/g) of aerobic microflora, coliform, and Escherichia coli O157:H7 (p < 0.05). There was no remarkable difference in decontamination efficacy between chlorine and ASC solution. In recent years, several sodium chlorite chemicals have been commercially available, and no difference in decontamination efficacy among the chemicals was observed when same concentration of sodium chlorite and citric acid were used. In addition, the reduction of E. coli O157:H7 population was influenced depending on the inoculation method and type of washing. It has been seen that dip-inoculated spinach leaves showed lower reduction than that of spot-inoculated spinach. After washing, populations of aerobic microflora, coliform, and E. coli O157:H7 were increased during storage at 10 degrees C, and washing condition before storage did not affect the subsequent increases in microbial population. Color of spinach leaves washed with ASC solution was not different from the color of those washed with water or chlorine solution, and washing with ASC solution was concluded to has no effect on appearance of spinach leaves.

  10. 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

  11. Pesticide residue analysis in parsley, lettuce and spinach by LC-MS/MS.

    PubMed

    Esturk, Okan; Yakar, Yasin; Ayhan, Zehra

    2014-03-01

    In this study, pesticide residues in parsley, lettuce and spinach (120 samples) were analyzed by the application of liquid chromatography-tandem mass spectrometry (LC-MS/MS). All samples of spinach, parsley or lettuce contained residues of three or more active substances. In parsley, carbendazim (100.0%), dichlorvos (100.0%), fenarimol (40.0%), pendimethalin (95.0%), in lettuce, diazinon (30.0%), dichlorvos (100.0%), pendimethalin (92.5%) phenthoate (12.5%), and in spinach, carbendazim (45.0%), cymoxanil (85.0%), dichlorvos (100.0%) and fenarimol (85.0%) were the significant active compounds. The maximum residue limits were exceeded in 28, 20 and 40 samples of parsley, lettuce and spinach, respectively. The results showed that there was a high occurrence of pesticide residues in parsley, lettuce and spinach samples from Hatay province, in which most of them were prohibited from use in Turkey for these vegetables. The contamination levels of these residues may be considered a serious public health problem according to the maximum residue limits (MRLs) of Turkey and the European Union (EU). PMID:24587520

  12. Distinct transcriptional profiles and phenotypes exhibited by Escherichia coli O157:H7 isolates related to the 2006 spinach-associated outbreak

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2006, an outbreak of Escherichia coli O157:H7 was linked to the consumption of ready-to-eat bagged spinach. The likely sources of pre-harvest spinach contamination were soil and water that became contaminated via cattle or feral pigs in the proximity of the spinach fields. In this study, we compa...

  13. 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...

  14. 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...

  15. 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…

  16. 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

    ... notice \\1\\ in the Federal Register on August 25, 2010 (75 FR 52302-52303, Docket No. APHIS-2010-0074), in... the Importation of Fresh Celery, Arugula, and Spinach From Colombia into the Continental United States... fresh celery, arugula, and spinach from Colombia. Based on the findings of three pest risk...

  17. 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

  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. Essential oils reduce Escherichia coli O157:H7 and Salmonella on spinach leaves without affecting produce quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of cinnamaldehyde and Sporan alone, or in combination with acetic acid in reducing E. coli O157:H7 and Salmonella on spinach leaves was investigated. Spinach leaves were inoculated with a cocktail of five-strain Salmonella or E. coli O157:H7, air-dried for 30 min, and then immersed in a...

  20. Systematic reconstruction of binding and stability landscapes of the fluorogenic aptamer spinach.

    PubMed

    Ketterer, Simon; Fuchs, David; Weber, Wilfried; Meier, Matthias

    2015-10-30

    Fluorogenic RNAs that are based on the complex formed by 3,5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI) derivatives and the RNA aptamer named Spinach were used to engineer a new generation of in vitro and in vivo sensors for bioanalytics. With the resolved crystal structure of the RNA/small molecule complex, the engineering map becomes available, but comprehensive information regarding the thermodynamic profile of the molecule is missing. Here, we reconstructed the full thermodynamic binding and stability landscapes between DFHBI and a truncated sequence of first-generation Spinach. For this purpose, we established a systematic screening procedure for single- and double-point mutations on a microfluidic large-scale integrated chip platform for 87-nt long RNAs. The thermodynamic profile with single base resolution was used to engineer an improved fluorogenic spinach generation via a directed rather than evolutional approach. PMID:26400180

  1. Systematic reconstruction of binding and stability landscapes of the fluorogenic aptamer spinach

    PubMed Central

    Ketterer, Simon; Fuchs, David; Weber, Wilfried; Meier, Matthias

    2015-01-01

    Fluorogenic RNAs that are based on the complex formed by 3,5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI) derivatives and the RNA aptamer named Spinach were used to engineer a new generation of in vitro and in vivo sensors for bioanalytics. With the resolved crystal structure of the RNA/small molecule complex, the engineering map becomes available, but comprehensive information regarding the thermodynamic profile of the molecule is missing. Here, we reconstructed the full thermodynamic binding and stability landscapes between DFHBI and a truncated sequence of first-generation Spinach. For this purpose, we established a systematic screening procedure for single- and double-point mutations on a microfluidic large-scale integrated chip platform for 87-nt long RNAs. The thermodynamic profile with single base resolution was used to engineer an improved fluorogenic spinach generation via a directed rather than evolutional approach. PMID:26400180

  2. Isolation, characterization, and structural organization of 10-formyltetrahydrofolate synthetase from spinach leaves.

    PubMed

    Nour, J M; Rabinowitz, J C

    1991-09-25

    One-carbon metabolism mediated by folate coenzymes plays an essential role in several major cellular processes. In the prokaryotes studied, three folate-dependent enzymes, 10-formyltetrahydrofolate synthetase (EC 6.3.4.3), 5,10-methenyltetrahydrofolate cyclohydrolase (EC 3.5.4.9), and 5,10-methylenetetrahydrofolate dehydrogenase (EC 1.5.1.5) generally exist as monofunctional or bifunctional proteins, whereas in eukaryotes the three activities are present on one polypeptide. The structural organization of these enzymes in plants had not previously been examined. We have purified the 10-formyltetrahydrofolate synthetase activity from spinach leaves to homogeneity and raised antibodies to it. The protein was a dimer with a subunit molecular weight of Mr = 67,000. The Km values for the three substrates, (6R)-tetrahydrofolate, ATP, and formate were 0.94, 0.043, and 21.9 mM, respectively. The enzyme required both monovalent and divalent cations for maximum activity. The 5,10-methylenetetrahydrofolate dehydrogenase and 5,10-methenyltetrahydrofolate cyclohydrolase activities of spinach coeluted separately from the 10-formyltetrahydrofolate synthetase activity on a Matrex Green-A column. On the same column, the activities of the yeast trifunctional C1-tetrahydrofolate synthase coeluted. In addition, antibodies raised to the purified spinach protein immunoinactivated and immunoprecipitated only the 10-formyltetrahydrofolate synthetase activity in a crude extract of spinach leaves. These results suggest that unlike the trifunctional form of C1-tetrahydrofolate synthase in the other eukaryotes examined, 10-formyltetrahydrofolate synthetase in spinach leaves is monofunctional and 5,10-methyl-enetetrahydrofolate dehydrogenase and 5,10-methenyltetrahydrofolate cyclohydrolase appear to be bifunctional. Although structurally dissimilar to the other eukaryotic trifunctional enzymes, the 35 amino-terminal residues of spinach 10-formyltetrahydrofolate synthetase showed 35% identity with six other tetrahydrofolate synthetases. PMID:1917961

  3. Pyruvate-Derived Amino Acids in Spinach Chloroplasts 1

    PubMed Central

    Schulze-Siebert, Detlef; Heineke, Dieter; Scharf, Horst; Schultz, Gernot

    1984-01-01

    A probable carbon flow from the Calvin cycle to branched chain amino acids and lipids via phosphoenolpyruvate (PEP) and pyruvate was examined in spinach (Spinacia oleracea) chloroplasts. The interpendence of metabolic pathways in and outside chloroplasts as well as product and feedback inhibition were studied. It was shown that alanine, aromatic, and small amounts of branched chain amino acids were formed from bicarbonate in purified intact chloroplasts. Addition of PEP only favored formation of aromatic amino acids. Mechanisms of regulation remained unclear. Concentrations of PEP and pyruvate within the chloroplast impermeable space during photosynthetic carbon fixation were 15 times higher than in the reaction medium. A direct carbon flow to pyruvate was identified (0.1 micromoles per milligram chlorophyll per hour). Pyruvate was taken up by intact chloroplasts slowly, leading to the formation of lysine, alanine, valine, and leucine plus isoleucine (approximate ratios, 100-500:60-100:40-100:2-10). The Km for the formation of valine and leucine plus isoleucine was estimated to be 0.1 millimolar. Ten micromolar glutamate optimized the transamination reaction regardless of whether bicarbonate or pyruvate was being applied. Alanine and valine formation was enhanced by the addition of acetate to the reaction mixture. The enhancement probably resulted from an inhibition of pyruvate dehydrogenase by acetyl-S-coenzyme A formed from acetate, and resulting accumulation of hydroxyethylthiamine diphosphate and pyruvate. High concentrations of valine and isoleucine inhibited their own and each others synthesis and enhanced alanine formation. When pyruvate was applied, only amino acids were formed; when complemented with bicarbonate, fatty acids were formed as well. This is probably the result of a requirement of acetyl-S-coenzyme A-carboxylase for bicarbonate. PMID:16663866

  4. Nutritional Composition of Water Spinach (Ipomoea aquatica Forsk.) Leaves

    NASA Astrophysics Data System (ADS)

    Umar, K. J.; Hassan, L. G.; Dangoggo, S. M.; Ladan, M. J.

    Analyses of the nutritional composition of water spinach (Ipomoea aquatica) Forsk leaves were carried out using standard methods of food analysis. The proximate composition as well as mineral elements were determined. The leaves were found on dry weight basis to have high moisture (72.83±0.29%), ash (10.83±0.80%), crude lipid (11.00±0.50%), crude fibre (17.67±0.35%) and available carbohydrate (54.20±0.68%), but low in crude protein content (6.30±0.27%). The leaves also have energy value (300.94±5.31 kcal/100 g) that is within the range reported in some Nigerian leafy vegetables. The mineral element contents were high with remarkable concentration of K (5,458.33±954.70 mg/100 g) and Fe (210.30±2.47 mg/100 g). Also the leaves content moderate concentrations of Na (135.00±2.50 mg/100 g), calcium (416.70±5.77 mg/100 g), Magnesium (301.64±12.69 mg/100 g) and P (109.29±0.55 mg/100 g), with low Cu (0.36±0.01 mg/100 g), Mn (2.14±0.22 mg/100 g) and Zn (2.47±0.27 mg/100 g) contents. Comparing the mineral content with recommended dietary allowance, it was showed that the plant leaves is good sources of K, Mn and Fe for all categories of people, while Mg is adequate enough for adult female and children. From the result, Ipomoea aquatica Forsk leaves could be used for nutritional purposes, due to the amount and diversity of nutrients it contains.

  5. Isolation of chlorophylls a and b from spinach by counter-current chromatography.

    PubMed

    Jubert, Carole; Bailey, George

    2007-01-26

    A method for the isolation of chlorophylls from spinach by counter-current chromatography was developed. An initial extraction protocol was devised to avoid the notorious sensitivity of chlorophylls to degradation by light, heat, oxygen, acids and bases. Further purification and separation of chlorophylls a and b were achieved using counter-current chromatography. Chlorophyll structures and purities were established by HPLC, fast atom bombardment mass spectrometry and nuclear magnetic resonance. Purity was estimated to be >95% (100% by HPLC). Typical yields from 30g of freeze-dried spinach were 300mg of chlorophyll a and 100mg of chlorophyll b. PMID:17164074

  6. Carbon Dioxide Fixation in the Light and in the Dark by Isolated Spinach Chloroplasts 1

    PubMed Central

    Avron, Mordhay; Gibbs, Martin

    1974-01-01

    Factors affecting CO2 fixation in the spinach (Spinacia oleracea) chloroplast were investigated. Free magnesium ions are shown to be highly inhibitory for photosynthetic CO2 fixation in isolated intact spinach chloroplasts. The pH optimum for CO2 fixation is about 8.5 but is dependent upon the reaction medium. Conditions are defined under which chloroplasts illuminated in the absence of CO2 accumulate ribulose 1,5-diphosphate, and fix CO2 in a subsequent dark period when high magnesium ion concentrations are provided. The regulation of photosynthetic CO2 assimilation by these factors is discussed. PMID:16658664

  7. 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. )

    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.

  8. Model based analysis of transient fluorescence yield induced by actinic laser flashes in spinach leaves and cells of green alga Chlorella pyrenoidosa Chick.

    PubMed

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

    2014-04-01

    Measurements of Single Flash Induced Transient Fluorescence Yield (SFITFY) on spinach leaves and whole cells of green thermophilic alga Chlorella pyrenoidosa Chick were analyzed for electron transfer (ET) steps and coupled proton transfer (PT) on both the donor and the acceptor side of the reaction center (RC) of photosystem II (PS II). A specially developed PS II model (Belyaeva etal., 2008, 2011a) allowed the determination of ET steps that occur in a hierarchically ordered time scale from nanoseconds to several seconds. Our study demonstrates that our SFITFY data is consistent with the concept of the reduction of P680(+) by YZ in both leaves and algae (studied on spinach leaves and cells of Chlorella pyrenoidosa Chick). The multiphasic P680(+) reduction kinetics by YZ in PS II core complexes with high oxygen evolution capacity was seen in both algae and leaves. Model simulation to fit SFITFY curves for dark adapted species used here gives the rate constants to verify nanosecond kinetic stages of P680(+) reduction by YZ in the redox state S1 of the water oxidizing complex (WOC) shown in Khn etal. (2004). Then a sequence of relaxation steps in the redox state S1, outlined by Renger (2012), occurs in both algae and leaves as a similar non-adiabatic ET reactions. Coupled PT is discussed briefly to understand a rearrangement of hydrogen bond protons in the protein matrix of the WOC (Umena etal., 2011). On the other hand, present studies showed a slower reoxidation of reduced QA by QB in algal cells as compared with that in a leaf that might be regarded as a consequence of differences of spatial domains at the QB-site in leaves compared to algae. Our comparative study helped to correlate theory with experimental data for molecular photosynthetic mechanisms in thylakoid membranes. PMID:24556534

  9. Differences in biofilm formation of produce and poultry Salmonella enterica isolates and their persistence on spinach plants.

    PubMed

    Patel, Jitendra; Singh, Manpreet; Macarisin, Dumitru; Sharma, Manan; Shelton, Daniel

    2013-12-01

    Spinach plants were irrigated biweekly with water containing 2.1 log CFU Salmonella/100 ml water (the maximum Escherichia coli MPN recommended by the Leafy Greens Marketing Agreement; LGMA), or 4.1 CFU Salmonella/100 ml water to determine Salmonella persistence on spinach leaves. Green Fluorescent protein expressing Salmonella were undetectable by most-probable number (MPN) at 24 h and 7 days following each irrigation event. This study indicates that Salmonella are unlikely to persist on spinach leaves when irrigation water is contaminated at a level below the LGMA standards. In a parallel study, persistence of Salmonella isolated from poultry or produce was compared following biweekly irrigation of spinach plants with water containing 6 log CFU Salmonella/100 ml. Produce Salmonella isolates formed greater biofilms on polystyrene, polycarbonate and stainless steel surfaces and persisted at significantly higher numbers on spinach leaves than those Salmonella from poultry origin during 35 days study. Poultry Salmonella isolates were undetectable (<1 log CFU/g) on spinach plants 7 days following each irrigation event when assayed by direct plating. This study indicates that Salmonella persistence on spinach leaves is affected by the source of contamination and the biofilm forming ability of the strain. PMID:24010621

  10. Cyclic electron transfer in plant leaf

    PubMed Central

    Joliot, Pierre; Joliot, Anne

    2002-01-01

    The turnover of linear and cyclic electron flows has been determined in fragments of dark-adapted spinach leaf by measuring the kinetics of fluorescence yield and of the transmembrane electrical potential changes under saturating illumination. When Photosystem (PS) II is inhibited, a cyclic electron flow around PSI operates transiently at a rate close to the maximum turnover of photosynthesis. When PSII is active, the cyclic flow operates with a similar rate during the first seconds of illumination. The high efficiency of the cyclic pathway implies that the cyclic and the linear transfer chains are structurally isolated one from the other. We propose that the cyclic pathway operates within a supercomplex including one PSI, one cytochrome bf complex, one plastocyanin, and one ferredoxin. The cyclic process induces the synthesis of ATP needed for the activation of the BensonCalvin cycle. A fraction of PSI (?50%), not included in the supercomplexes, participates in the linear pathway. The illumination would induce a dissociation of the supercomplexes that progressively increases the fraction of PSI involved in the linear pathway. PMID:12119384

  11. Evaluation of Oxalate Concentration in the U.S. Spinach Germplasm Collection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In addition to its high nutrient content, spinach (Spinacia oleracea L.) is also known to have greater amount of oxalic acid than most crops. Oxalic acid may form crystals with minerals to reduce the bioavailability and absorption of calcium and iron in diets, and calcium oxalate may deposit in the...

  12. Tandem Spinach Array for mRNA Imaging in Living Bacterial Cells.

    PubMed

    Zhang, Jichuan; Fei, Jingyi; Leslie, Benjamin J; Han, Kyu Young; Kuhlman, Thomas E; Ha, Taekjip

    2015-01-01

    Live cell RNA imaging using genetically encoded fluorescent labels is an important tool for monitoring RNA activities. A recently reported RNA aptamer-fluorogen system, the Spinach, in which an RNA aptamer binds and induces the fluorescence of a GFP-like 3,5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI) ligand, can be readily tagged to the RNA of interest. Although the aptamer-fluorogen system is sufficient for imaging highly abundant non-coding RNAs (tRNAs, rRNAs, etc.), it performs poorly for mRNA imaging due to low brightness. In addition, whether the aptamer-fluorogen system may perturb the native RNA characteristics has not been systematically characterized at the levels of RNA transcription, translation and degradation. To increase the brightness of these aptamer-fluorogen systems, we constructed and tested tandem arrays containing multiple Spinach aptamers (8-64 aptamer repeats). Such arrays enhanced the brightness of the tagged mRNA molecules by up to ~17 fold in living cells. Strong laser excitation with pulsed illumination further increased the imaging sensitivity of Spinach array-tagged RNAs. Moreover, transcriptional fusion to the Spinach array did not affect mRNA transcription, translation or degradation, indicating that aptamer arrays might be a generalizable labeling method for high-performance and low-perturbation live cell RNA imaging. PMID:26612428

  13. GROWTH RESPONSE IN SPINACH TO SEQUENTIAL AND SIMULTANEOUS EXPOSURE TO NO2 AND SO2

    EPA Science Inventory

    Spinach (Spinacia oleracea) was exposed intermittently to NO2 and SO2 (2 hours/week; 0.8 or 1.5ppm) in a simultaneous or sequential fashion over the 42-day growth period. Nighttime simultaneous exposure to NO2 and SO2 reduced growth and altered assimilate partitioning to the root...

  14. De novo and comparative transcriptome analysis of cultivated and wild spinach.

    PubMed

    Xu, Chenxi; Jiao, Chen; Zheng, Yi; Sun, Honghe; Liu, Wenli; Cai, Xiaofeng; Wang, Xiaoli; Liu, Shuang; Xu, Yimin; Mou, Beiquan; Dai, Shaojun; Fei, Zhangjun; Wang, Quanhua

    2015-01-01

    Spinach (Spinacia oleracea L.) is an economically important green leafy vegetable crop. In this study, we performed deep transcriptome sequencing for nine spinach accessions: three from cultivated S. oleracea, three from wild S. turkestanica and three from wild S. tetrandra. A total of approximately 100 million high-quality reads were generated, which were de novo assembled into 72,151 unigenes with a total length of 46.5 Mb. By comparing sequences of these unigenes against different protein databases, nearly 60% of them were annotated and 50% could be assigned with Gene Ontology terms. A total of 387 metabolic pathways were predicted from the assembled spinach unigenes. From the transcriptome sequencing data, we were able to identify a total of ~320,000 high-quality single nucleotide polymorphisms (SNPs). Phylogenetic analyses using SNPs as well as gene expression profiles indicated that S. turkestanica was more closely related to the cultivated S. oleracea than S. tetrandra. A large number of genes involved in responses to biotic and abiotic stresses were found to be differentially expressed between the cultivated and wild spinach. Finally, an interactive online database (http://www.spinachbase.org) was developed to allow the research community to efficiently retrieve, query, mine and analyze our transcriptome dataset. PMID:26635144

  15. 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...

  16. 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...

  17. ASSESSING GENETIC DIVERSITY OF SPINACH (SPINACIA OLERACEA L.) GERMPLASM USING TRAP MARKERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Target region amplified polymorphism (TRAP) markers were used to evaluate genetic variability among 48 accessions of spinach (Spinacia oleracea L.), an economically important leafy vegetable crop in many countries. Thirty-eight accessions collected and preserved by the USDA National Plant Germplasm ...

  18. De novo and comparative transcriptome analysis of cultivated and wild spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, we performed deep transcriptome sequencing for nine spinach (Spinacia oleracea L., 2n = 2 = 12) accessions, three from cultivated S. oleracea, three from wild S. turkestanica and three from wild S. tetrandra, using the Illumina sequencing technology. A total of approximately 100 mill...

  19. Responses of spinach to salinity and nutrient deficiency in growth, physiology and nutritional value

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salinity and nutrient depleted soil are major constraints to crop production, especially for vegetable crops. The effects of salinity and nutrient deficiency on spinach were evaluated in sand cultures under greenhouse conditions. Plants were watered every day with Hoagland nutrition solution, depriv...

  20. 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...

  1. [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

  2. 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 (t = 1.3 10?3 second). PMID:16656366

  3. De novo and comparative transcriptome analysis of cultivated and wild spinach

    PubMed Central

    Xu, Chenxi; Jiao, Chen; Zheng, Yi; Sun, Honghe; Liu, Wenli; Cai, Xiaofeng; Wang, Xiaoli; Liu, Shuang; Xu, Yimin; Mou, Beiquan; Dai, Shaojun; Fei, Zhangjun; Wang, Quanhua

    2015-01-01

    Spinach (Spinacia oleracea L.) is an economically important green leafy vegetable crop. In this study, we performed deep transcriptome sequencing for nine spinach accessions: three from cultivated S. oleracea, three from wild S. turkestanica and three from wild S. tetrandra. A total of approximately 100 million high-quality reads were generated, which were de novo assembled into 72,151 unigenes with a total length of 46.5 Mb. By comparing sequences of these unigenes against different protein databases, nearly 60% of them were annotated and 50% could be assigned with Gene Ontology terms. A total of 387 metabolic pathways were predicted from the assembled spinach unigenes. From the transcriptome sequencing data, we were able to identify a total of ~320,000 high-quality single nucleotide polymorphisms (SNPs). Phylogenetic analyses using SNPs as well as gene expression profiles indicated that S. turkestanica was more closely related to the cultivated S. oleracea than S. tetrandra. A large number of genes involved in responses to biotic and abiotic stresses were found to be differentially expressed between the cultivated and wild spinach. Finally, an interactive online database (http://www.spinachbase.org) was developed to allow the research community to efficiently retrieve, query, mine and analyze our transcriptome dataset. PMID:26635144

  4. Internalization of E. coli O157:H7 in spinach cultivated in soil and hydroponic media

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Internalization of E. coli O157:H7 into spinach plants through root uptake is a potential route of contamination. Previous studies that have investigated uptake of E. coli O157:H7 into leafy greens have expressed green fluorescent protein (gfp) from a plasmid, possibly limiting detecti...

  5. 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...

  6. Tandem Spinach Array for mRNA Imaging in Living Bacterial Cells

    PubMed Central

    Zhang, Jichuan; Fei, Jingyi; Leslie, Benjamin J.; Han, Kyu Young; Kuhlman, Thomas E.; Ha, Taekjip

    2015-01-01

    Live cell RNA imaging using genetically encoded fluorescent labels is an important tool for monitoring RNA activities. A recently reported RNA aptamer-fluorogen system, the Spinach, in which an RNA aptamer binds and induces the fluorescence of a GFP-like 3,5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI) ligand, can be readily tagged to the RNA of interest. Although the aptamerfluorogen system is sufficient for imaging highly abundant non-coding RNAs (tRNAs, rRNAs, etc.), it performs poorly for mRNA imaging due to low brightness. In addition, whether the aptamer-fluorogen system may perturb the native RNA characteristics has not been systematically characterized at the levels of RNA transcription, translation and degradation. To increase the brightness of these aptamer-fluorogen systems, we constructed and tested tandem arrays containing multiple Spinach aptamers (864 aptamer repeats). Such arrays enhanced the brightness of the tagged mRNA molecules by up to ~17 fold in living cells. Strong laser excitation with pulsed illumination further increased the imaging sensitivity of Spinach array-tagged RNAs. Moreover, transcriptional fusion to the Spinach array did not affect mRNA transcription, translation or degradation, indicating that aptamer arrays might be a generalizable labeling method for high-performance and low-perturbation live cell RNA imaging. PMID:26612428

  7. 24-epibrassinolide and 20-hydroxyecdysone affect photosynthesis differently in maize and spinach.

    PubMed

    Rothová, Olga; Holá, Dana; Kočová, Marie; Tůmová, Lenka; Hnilička, František; Hniličková, 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

  8. First report of Phytophthora root rot, caused by Phytophthora cryptogea, on spinach in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2006 and 2007, commercially grown spinach (Spinacia oleracea) in California’s coastal Salinas Valley (Monterey County) was affected by an unreported root rot disease. Disease was limited to patches along the edges of fields. Affected plants were stunted with chlorotic older leaves. As disease pro...

  9. 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...

  10. 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...

  11. Adherence of curli producing Shiga-toxigenic Escherichia coli to baby spinach leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cellular appendages, such as curli fibers have been suggested to be involved in STEC persistence in fresh produce as these curli are critical in biofilm formation and adherence to animal cells. We determined the role of curli in attachment of STEC on spinach leaves. The curli expression by wild-ty...

  12. Acute Effects of a Spinach Extract Rich in Thylakoids on Satiety: A Randomized Controlled Crossover Trial

    PubMed Central

    Rebello, Candida J.; Chu, Jessica; Beyl, Robbie; Edwall, Dan; Erlanson-Albertsson, Charlotte; Greenway, Frank L.

    2015-01-01

    Objective: By retarding fat digestion, thylakoids, the internal photosynthetic membrane system of green plants, promote the release of satiety hormones. This study examined the effect of consuming a single dose of concentrated extract of thylakoids from spinach on satiety, food intake, lipids, and glucose compared to a placebo. Design: Sixty overweight and obese individuals enrolled in a double-blind randomized crossover study consumed the spinach extract or placebo in random order at least a week apart. Blood was drawn for assessments of lipids and glucose before a standard breakfast meal, followed 4 hours later by a 5 g dose of the extract and a standard lunch. Visual analog scales were administered before lunch and at intervals until an ad libitum pizza dinner served 4 hours later. Two hours after lunch a second blood draw was conducted. Mixed models were used to analyze response changes. Results: Compared to placebo, consuming the spinach extract reduced hunger (p < 0.01) and longing for food over 2 hours (p < 0.01) and increased postprandial plasma glucose concentrations (p < 0.01). There were no differences in plasma lipids and energy intake at dinner, but males showed a trend toward decreased energy intake (p = 0.08). Conclusions: At this dose, the spinach extract containing thylakoids increases satiety over a 2-hour period compared to a placebo. Thylakoid consumption may influence gender-specific food cravings. PMID:26029978

  13. 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 ...

  14. 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

  15. Mapping leaf surface landscapes.

    PubMed

    Mechaber, W L; Marshall, D B; Mechaber, R A; Jobe, R T; Chew, F S

    1996-05-14

    Leaf surfaces provide the ecologically relevant landscapes to those organisms that encounter or colonize the leaf surface. Leaf surface topography directly affects microhabitat availability for colonizing microbes, microhabitat quality and acceptability for insects, and the efficacy of agricultural spray applications. Prior detailed mechanistic studies that examined particular fungi-plant and pollinator-plant interactions have demonstrated the importance of plant surface topography or roughness in determining the outcome of the interactions. Until now, however, it has not been possible to measure accurately the topography--i.e., the three-dimensional structure--of such leaf surfaces or to record precise changes in patterns of leaf surface elevation over time. Using contact mode atomic force microscopy, we measured three-dimensional coordinates of upper leaf surfaces of Vaccinium macrocarpon (cranberry), a perennial plant, on leaves of two age classes. We then produced topographic maps of these leaf surfaces, which revealed striking differences between age classes of leaves: old leaves have much rougher surfaces than those of young leaves. Atomic force microscope measurements were analyzed by lag (1) autocorrelation estimates of leaf surfaces by age class. We suggest that the changes in topography result from removal of epicuticular lipids and that the changes in leaf surface topography influence phylloplane ecology. Visualizing and mapping leaf surfaces permit detailed investigations into leaf surface-mediated phenomena, improving our understanding of phylloplane interactions. PMID:11607676

  16. Effect of γ-irradiation on the thermomechanical and morphological properties of chitosan obtained from prawn shell: Evaluation of potential for irradiated chitosan as plant growth stimulator for Malabar spinach

    NASA Astrophysics Data System (ADS)

    Rahman, Mohammed Mizanur; Kabir, Shahriar; Rashid, Taslim Ur; Nesa, Bodrun; Nasrin, Romana; Haque, Papia; Khan, Mubarak A.

    2013-01-01

    In the present study we have synthesized chitosan from waste prawn shell via γ-irradiation of chitin and subsequent alkaline treatment. The detailed experimental studies demonstrated that nonirradiated chitin deacetylated by 40% NaOH solution showed 72% degree of deacetylation (DD), however 50 kGy irradiated chitin, deacetylated by 20% NaOH demonstrated 81.5% DD. Chitosan in solid state as obtained from γ-irradiation of chitin was further irradiated by different doses (2-100 kGy) of gamma irradiation and the effects of irradiation on the molecular weight, thermo-mechanical by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and antimicrobial properties were evaluated with respect to nonirradiated chitosan sample. Gamma irradiation of chitosan with a dose of 100 kGy caused a decrease in average molecular weight from 1.9×105 to 6.5×104 Da and thus increased its solubility in water. Nonirradiated and γ-irradiated chitosan at concentration 1% (w/w) in water were prepared and used to evaluate of its potentiality for growth stimulation of Malabar spinach. The chitosan solution was sprayed on the specimen plants and neighboring soil where germinations were taken place and various plant growth parameters such as plant height, number of leaves, leaf areas, dry and wet weight of the plants and roots were investigated. The details study revealed that application of 30 kGy irradiated chitosan yielded 60% higher growth of the Malabar spinach than that obtained from nonirradiated chitosan. The data are consistent with preliminary results from field experiments and unambiguously confirms that a minor amount of chitosan has a profound effect on the growth and development of Malabar spinach.

  17. Antioxidant Effects of Spinach (Spinacia oleracea L.) Supplementation in Hyperlipidemic Rats

    PubMed Central

    Ko, Sang-Heui; Park, Jae-Hee; Kim, So-Yun; Lee, Seon Woo; Chun, Soon-Sil; Park, Eunju

    2014-01-01

    Increased consumption of fresh vegetables that are high in polyphenols has been associated with a reduced risk of oxidative stress-induced disease. The present study aimed to evaluate the antioxidant effects of spinach in vitro and in vivo in hyperlipidemic rats. For measurement of in vitro antioxidant activity, spinach was subjected to hot water extraction (WE) or ethanol extraction (EE) and examined for total polyphenol content (TPC), oxygen radical absorbance capacity (ORAC), cellular antioxidant activity (CAA), and antigenotoxic activity. The in vivo antioxidant activity of spinach was assessed using blood and liver lipid profiles and antioxidant status in rats fed a high fat-cholesterol diet (HFCD) for 6 weeks. The TPC of WE and EE were shown as 1.50.0 and 0.50.0 mg GAE/g, respectively. Increasing the concentration of the extracts resulted in increased ORAC value, CAA, and antigenotoxic activity for all extracts tested. HFCD-fed rats displayed hyperlipidemia and increased oxidative stress, as indicated by a significant rise in blood and liver lipid profiles, an increase in plasma conjugated diene concentration, an increase in liver thiobarbituric acid reactive substances (TBARS) level, and a significant decrease in manganese superoxide dismutase (Mn-SOD) activity compared with rats fed normal diet. However, administration of 5% spinach showed a beneficial effect in HFCD rats, as indicated by decreased liver TBARS level and DNA damage in leukocyte and increased plasma conjugated dienes and Mn-SOD activity. Thus, the antioxidant activity of spinach may be an effective way to ameliorate high fat and cholesterol diet-induced oxidative stress. PMID:24772405

  18. Antioxidant Effects of Spinach (Spinacia oleracea L.) Supplementation in Hyperlipidemic Rats.

    PubMed

    Ko, Sang-Heui; Park, Jae-Hee; Kim, So-Yun; Lee, Seon Woo; Chun, Soon-Sil; Park, Eunju

    2014-01-01

    Increased consumption of fresh vegetables that are high in polyphenols has been associated with a reduced risk of oxidative stress-induced disease. The present study aimed to evaluate the antioxidant effects of spinach in vitro and in vivo in hyperlipidemic rats. For measurement of in vitro antioxidant activity, spinach was subjected to hot water extraction (WE) or ethanol extraction (EE) and examined for total polyphenol content (TPC), oxygen radical absorbance capacity (ORAC), cellular antioxidant activity (CAA), and antigenotoxic activity. The in vivo antioxidant activity of spinach was assessed using blood and liver lipid profiles and antioxidant status in rats fed a high fat-cholesterol diet (HFCD) for 6 weeks. The TPC of WE and EE were shown as 1.5±0.0 and 0.5±0.0 mg GAE/g, respectively. Increasing the concentration of the extracts resulted in increased ORAC value, CAA, and antigenotoxic activity for all extracts tested. HFCD-fed rats displayed hyperlipidemia and increased oxidative stress, as indicated by a significant rise in blood and liver lipid profiles, an increase in plasma conjugated diene concentration, an increase in liver thiobarbituric acid reactive substances (TBARS) level, and a significant decrease in manganese superoxide dismutase (Mn-SOD) activity compared with rats fed normal diet. However, administration of 5% spinach showed a beneficial effect in HFCD rats, as indicated by decreased liver TBARS level and DNA damage in leukocyte and increased plasma conjugated dienes and Mn-SOD activity. Thus, the antioxidant activity of spinach may be an effective way to ameliorate high fat and cholesterol diet-induced oxidative stress. PMID:24772405

  19. Automated immunomagnetic separation for the detection of Escherichia coli O157:H7 from spinach.

    PubMed

    Chen, Jing; Shi, Xianming; Gehring, Andrew G; Paoli, George C

    2014-06-01

    Escherichia coli O157:H7 is a major cause of foodborne illness and methods for rapid and sensitive detection of this deadly pathogen are needed to protect consumers. The use of immunomagnetic separation (IMS) for capturing and detecting foodborne pathogens has gained popularity, partially due to the introduction of automated and high throughput IMS instrumentation. Three methods for automated IMS that test different sample volumes, Kingfisher mL, Pathatrix Auto, and Pathatrix Ultra, were compared using microbiological detection of E. coli O157:H7 from buffered peptone water (BPW), in the presence of background microbial flora derived from spinach leaves, and from culture enrichments from artificially contaminated spinach leaves. The average efficiencies of capture of E. coli O157:H7 using the three methods were 32.1%, 3.7%, and 1.3%, respectively, in BPW; 43.4%, 8.8%, 2.9%, respectively, in the presence of spinach microbial flora; and 63.0%, 7.0%, and 6.3%, respectively, from artificially contaminated spinach. Despite the large differences in IMS capture efficiencies between the KingFisher and two Pathatrix methods, all three methods allowed the detection of E. coli O157:H7 from spinach that was artificially contaminated with the pathogen at relatively high (25 cfu/30 g sample) and low (1 cfu/30 g sample) levels after 4-6h of culture enrichment. The differences in capture efficiency were compensated for by the differences in sample volume used by the KingFisher mL (1 mL), Pathatrix Auto (50 mL) and Pathatrix Ultra (250 mL) instruments. Thus, despite the reduced capture efficiencies observed for the Pathatrix methods, the large increase in sample volume results in a greater number of captured cells for downstream detection resulting in improved detection sensitivity. PMID:24718031

  20. Spatial and Temporal Factors Associated with an Increased Prevalence of Listeria monocytogenes in Spinach Fields in New York State

    PubMed Central

    Weller, Daniel; Wiedmann, Martin

    2015-01-01

    While rain and irrigation events have been associated with an increased prevalence of foodborne pathogens in produce production environments, quantitative data are needed to determine the effects of various spatial and temporal factors on the risk of produce contamination following these events. This study was performed to quantify these effects and to determine the impact of rain and irrigation events on the detection frequency and diversity of Listeria species (including L. monocytogenes) and L. monocytogenes in produce fields. Two spinach fields, with high and low predicted risks of L. monocytogenes isolation, were sampled 24, 48, 72, and 144 to 192 h following irrigation and rain events. Predicted risk was a function of the field's proximity to water and roads. Factors were evaluated for their association with Listeria species and L. monocytogenes isolation by using generalized linear mixed models (GLMMs). In total, 1,492 (1,092 soil, 334 leaf, 14 fecal, and 52 water) samples were collected. According to the GLMM, the likelihood of Listeria species and L. monocytogenes isolation from soil samples was highest during the 24 h immediately following an event (odds ratios [ORs] of 7.7 and 25, respectively). Additionally, Listeria species and L. monocytogenes isolates associated with irrigation events showed significantly lower sigB allele type diversity than did isolates associated with precipitation events (P = <0.001), suggesting that irrigation water may be a point source of L. monocytogenes contamination. Small changes in management practices (e.g., not irrigating fields before harvest) may therefore reduce the risk of L. monocytogenes contamination of fresh produce. PMID:26116668

  1. Spatial and Temporal Factors Associated with an Increased Prevalence of Listeria monocytogenes in Spinach Fields in New York State.

    PubMed

    Weller, Daniel; Wiedmann, Martin; Strawn, Laura K

    2015-09-01

    While rain and irrigation events have been associated with an increased prevalence of foodborne pathogens in produce production environments, quantitative data are needed to determine the effects of various spatial and temporal factors on the risk of produce contamination following these events. This study was performed to quantify these effects and to determine the impact of rain and irrigation events on the detection frequency and diversity of Listeria species (including L. monocytogenes) and L. monocytogenes in produce fields. Two spinach fields, with high and low predicted risks of L. monocytogenes isolation, were sampled 24, 48, 72, and 144 to 192 h following irrigation and rain events. Predicted risk was a function of the field's proximity to water and roads. Factors were evaluated for their association with Listeria species and L. monocytogenes isolation by using generalized linear mixed models (GLMMs). In total, 1,492 (1,092 soil, 334 leaf, 14 fecal, and 52 water) samples were collected. According to the GLMM, the likelihood of Listeria species and L. monocytogenes isolation from soil samples was highest during the 24 h immediately following an event (odds ratios [ORs] of 7.7 and 25, respectively). Additionally, Listeria species and L. monocytogenes isolates associated with irrigation events showed significantly lower sigB allele type diversity than did isolates associated with precipitation events (P = <0.001), suggesting that irrigation water may be a point source of L. monocytogenes contamination. Small changes in management practices (e.g., not irrigating fields before harvest) may therefore reduce the risk of L. monocytogenes contamination of fresh produce. PMID:26116668

  2. Structure and Stability of the Spinach Aquaporin SoPIP2;1 in Detergent Micelles and Lipid Membranes

    PubMed Central

    Plasencia, Inés; Survery, Sabeen; Ibragimova, Sania; Hansen, Jesper S.; Kjellbom, Per; Helix-Nielsen, Claus; Johanson, Urban; Mouritsen, Ole G.

    2011-01-01

    Background SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize reconstitution of the purified protein into biomimetic systems, we have here for the first time characterized the structural stability of SoPIP2;1. Methodology/Principal Finding We have characterized the protein structural stability after purification and after reconstitution into detergent micelles and proteoliposomes using circular dichroism and fluorescence spectroscopy techniques. The structure of SoPIP2;1 was analyzed either with the protein solubilized with octyl-β-D-glucopyranoside (OG) or reconstituted into lipid membranes formed by E. coli lipids, diphytanoylphosphatidylcholine (DPhPC), or reconstituted into lipid membranes formed from mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE), 1-palmitoyl-2oleoyl-phosphatidylethanolamine (POPE), 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS), and ergosterol. Generally, SoPIP2;1 secondary structure was found to be predominantly α-helical in accordance with crystallographic data. The protein has a high thermal structural stability in detergent solutions, with an irreversible thermal unfolding occurring at a melting temperature of 58°C. Incorporation of the protein into lipid membranes increases the structural stability as evidenced by an increased melting temperature of up to 70°C. Conclusion/Significance The results of this study provide insights into SoPIP2;1 stability in various host membranes and suggest suitable choices of detergent and lipid composition for reconstitution of SoPIP2;1 into biomimetic membranes for biotechnological applications. PMID:21339815

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  4. 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...

  5. GENETIC DIVERSITY OF 38 SPINACH (SPINACIA OLERACEA L.) GERMPLASM ACCESSIONS AND TEN COMMERCIAL HYBRIDS ASSESSED BY TRAP MARKERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Target region amplification polymorphism (TRAP) markers were used to assess genetic variability among 38 germplasm accessions and ten commercial hybrids of spinach (Spinacia oleracea L.), an economically important leafy vegetable crop in many countries. Germplasm accessions with different geographic...

  6. Understanding the Photophysics of the Spinach-DFHBI RNA Aptamer-Fluorogen Complex to Improve Live Cell RNA Imaging

    PubMed Central

    Han, Kyu Young; Leslie, Benjamin J.; Fei, Jingyi; Zhang, Jichuan; Ha, Taekjip

    2014-01-01

    The use of aptamer-fluorogen complexes is an emerging strategy for RNA imaging. Despite promise for cellular imaging and sensing, the low fluorescence intensity of the Spinach-DFHBI RNA aptamer-fluorogen complex hampers its utility in quantitative live-cell and high-resolution imaging applications. Here we report that illumination of the Spinach-fluorogen complex induces photoconversion and subsequently fluorogen dissociation, leading to fast fluorescence decay and fluorogen concentration-dependent recovery. The fluorescence lifetime of Spinach-DFHBI is 4.0 ± 0.1 ns irrespective of the extent of photoconversion. We detail a low-repetition illumination scheme that enables us to maximize the potential of the Spinach-DFHBI RNA imaging tag in living cells. PMID:24286188

  7. Nitrogen removal from eutrophic water by floating-bed-grown water spinach (Ipomoea aquatica Forsk.) with ion implantation.

    PubMed

    Li, Miao; Wu, Yue-Jin; Yu, Zeng-Liang; Sheng, Guo-Ping; Yu, Han-Qing

    2007-07-01

    The aim of this study was to investigate the use of water spinach (Ipomoea aquatica Forsk.) with N(+) ion-beam implantation for removal of nutrient species from eutrophic water. The mutated water spinach was grown on floating beds, and growth chambers were used to examine the growth of three cultivars of water spinach with ion implantation for 14 days in simulated eutrophic water at both high and low nitrogen levels. The specific weight growth rates of three cultivars of water spinach with ion implantation were significantly higher than the control, and their NO(3)-N and NH(4)-N removal efficiencies were also greater than those of the control. Furthermore, compared with the control, the nitrogen contents in the plant biomass with ion implantation were higher as well. PMID:17524443

  8. De novo transcriptome sequencing and gene expression profiling of spinach (Spinacia oleracea L.) leaves under heat stress.

    PubMed

    Yan, Jun; Yu, Li; Xuan, Jiping; Lu, Ying; Lu, Shijun; Zhu, Weimin

    2016-01-01

    Spinach (Spinacia oleracea) has cold tolerant but heat sensitive characteristics. The spinach variety 'Island,' is suitable for summer periods. There is lack molecular information available for spinach in response to heat stress. In this study, high throughput de novo transcriptome sequencing and gene expression analyses were carried out at different spinach variety 'Island' leaves (grown at 24 °C (control), exposed to 35 °C for 30 min (S1), and 5 h (S2)). A total of 133,200,898 clean reads were assembled into 59,413 unigenes (average size 1259.55 bp). 33,573 unigenes could match to public databases. The DEG of controls vs S1 was 986, the DEG of control vs S2 was 1741 and the DEG of S1 vs S2 was 1587. Gene Ontology (GO) and pathway enrichment analysis indicated that a great deal of heat-responsive genes and other stress-responsive genes were identified in these DEGs, suggesting that the heat stress may have induced an extensive abiotic stress effect. Comparative transcriptome analysis found 896 unique genes in spinach heat response transcript. The expression patterns of 13 selected genes were verified by RT-qPCR (quantitative real-time PCR). Our study found a series of candidate genes and pathways that may be related to heat resistance in spinach. PMID:26857466

  9. Sensitive determination of cadmium in brown rice and spinach by flame atomic absorption spectrometry with solid-phase extraction.

    PubMed

    Akamatsu, Shigeki; Yoshioka, Naoki; Mitsuhashi, Takao

    2012-01-01

    A sensitive flame atomic absorption spectrometry (FAAS) method was developed for the determination of cadmium (Cd) in brown rice and spinach. The method involves extraction with 1 M hydrochloric acid (HCl), followed by a selective pre-concentration by solid-phase extraction (SPE). The pH of the loading sample solution was adjusted to 4.0 for the brown rice and to 5.0 for the spinach. The masking agents, tartrate and citrate, were required for the spinach before pH adjustment. The SPE step achieved a 20-fold enrichment of the sample solution. The limits of quantification (LOQs) were 0.0054 mg kg⁻¹ for the brown rice and 0.0022 mg kg⁻¹ for the spinach, being more sensitive than those of AOAC Official method 999.10. A single-laboratory validation was performed by testing spiked samples at 0.04 and 0.08 mg kg⁻¹ for the brown rice, and 0.02 and 0.04 mg kg⁻¹ for the spinach. The average recoveries were 93.3-96.9% with relative standard deviations (RSDs) of 4.1-8.2% for brown rice, and 90.5-91.9% with RSDs of 5.8-10.0% for spinach. PMID:22849394

  10. De novo transcriptome sequencing and gene expression profiling of spinach (Spinacia oleracea L.) leaves under heat stress

    PubMed Central

    Yan, Jun; Yu, Li; Xuan, Jiping; Lu, Ying; Lu, Shijun; Zhu, Weimin

    2016-01-01

    Spinach (Spinacia oleracea) has cold tolerant but heat sensitive characteristics. The spinach variety ‘Island,’ is suitable for summer periods. There is lack molecular information available for spinach in response to heat stress. In this study, high throughput de novo transcriptome sequencing and gene expression analyses were carried out at different spinach variety ‘Island’ leaves (grown at 24 °C (control), exposed to 35 °C for 30 min (S1), and 5 h (S2)). A total of 133,200,898 clean reads were assembled into 59,413 unigenes (average size 1259.55 bp). 33,573 unigenes could match to public databases. The DEG of controls vs S1 was 986, the DEG of control vs S2 was 1741 and the DEG of S1 vs S2 was 1587. Gene Ontology (GO) and pathway enrichment analysis indicated that a great deal of heat-responsive genes and other stress-responsive genes were identified in these DEGs, suggesting that the heat stress may have induced an extensive abiotic stress effect. Comparative transcriptome analysis found 896 unique genes in spinach heat response transcript. The expression patterns of 13 selected genes were verified by RT-qPCR (quantitative real-time PCR). Our study found a series of candidate genes and pathways that may be related to heat resistance in spinach. PMID:26857466

  11. Increasing total and biologically active chromium in wheat grain and spinach by spraying with chromium salts

    SciTech Connect

    Vicini, F.A.; Ellis, B.G.

    1981-06-01

    Recently, chromium has been shown to be necessary for glucose metabolism in man. But most plant species greatly restrict the uptake of Cr. This study was conducted to determine if both total and biologically active Cr could be increased in wheat grain or spinach by spraying the plants with either Cr/sub 2/(SO/sub 4/)/sub 3/ or Cr-EDTA. Concentrations of Cr in wheat grain were about doubled in a greenhouse experiment by spraying with either Cr source. Biologically active Cr (estimated by extraction with ethanol or NH/sub 4/OH) was increased from about 40 to greater than 50% of total Cr when wheat was sprayed with Cr salts. Total Cr in spinach leaves was increased by as much as 10-fold by spraying, with the sulfate source being more effective than the EDTA.

  12. Fat Metabolism in Higher Plants: LXII. Stearl-acyl Carrier Protein Desaturase from Spinach Chloroplasts.

    PubMed

    Jacobson, B S; Jaworski, J G; Stumpf, P K

    1974-10-01

    Stearyl-acyl carrier protein desaturase (EC 1.14.99.6), present in the stroma fraction of spinach (Spinacia oleracea) chloroplasts, rapidly desaturated enzymatically prepared stearyl-acyl carrier protein to oleic acid. No other substrates were desaturated. In addition to stearyl-acyl carrier protein, reduced ferredoxin was an essential component of the system. The electron donor systems were either ascorbate, dichlorophenolindophenol, photosystem I and light, or NADPH and ferredoxin-NADP reductase. The desaturase was more active in extracts prepared from chloroplasts obtained from immature spinach leaves than from mature leaves. Stearyl-acyl carrier protein desaturase also occurs in soluble extracts of avocado (Persea americana Mill.) mesocarp and of developing safflower (Carthamus tinctorius) seeds. PMID:16658913

  13. Impact of coal mine dump contaminated soils on elemental uptake by Spinacia oleracea (spinach)

    SciTech Connect

    Chunilall, V.; Kindness, A.; Jonnalagadda, S.B.

    2006-07-01

    The elemental uptake and the growth response of Spinacia oleracea (spinach) to the soil contaminated with the South African bituminous coal mine dump soil, viz. 0%, 5%, 15%, and 25% w/w, was investigated. The contaminated soils were analyzed for pH, cation exchange capacity (CEC), soil organic matter (SOM), and concentrations of selected heavy metals. The pH, SOM, and CEC decreased with an increase in contamination indicating the acidic nature of coal mine soil and the raise in the soil binding sites. The distribution of Fe, Mn, Ni, Cd, and Pb in the roots and leaves of the plants was determined in two stages of plant growth. Spinach showed high accumulation of Fe and increased levels of Ni and Cd with an increase in contamination. No plant growth was recorded with 25% contamination.

  14. Gamma irradiation dose: Effects on spinach baby-leaf ascorbic acid, carotenoids, folate, alpha-tocopherol, and phylloquinone concentrations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ionizing radiation of fruits and vegetables, in the form of gamma rays or electron beams, is effective in overcoming quarantine barriers in trade, decontamination, disinfestation and prolonging shelf life, but a void of information persists on ionizing radiation effects of vitamin profiles in indivi...

  15. 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...

  16. 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

  17. Spinach - A software library for simulation of spin dynamics in large spin systems

    NASA Astrophysics Data System (ADS)

    Hogben, H. J.; Krzystyniak, M.; Charnock, G. T. P.; Hore, P. J.; Kuprov, Ilya

    2011-02-01

    We introduce a software library incorporating our recent research into efficient simulation algorithms for large spin systems. Liouville space simulations (including symmetry, relaxation and chemical kinetics) of most liquid-state NMR experiments on 40+ spin systems can now be performed without effort on a desktop workstation. Much progress has also been made with improving the efficiency of ESR, solid state NMR and Spin Chemistry simulations. Spinach is available for download at http://spindynamics.org.

  18. Uptake and transport of roxarsone and its metabolites in water spinach as affected by phosphate supply.

    PubMed

    Yao, Lixian; Li, Guoliang; Dang, Zhi; Yang, Baomei; He, Zhaohuan; Zhou, Changmin

    2010-04-01

    Roxarsone (ROX) is widely used as a feed additive in intensive animal production. While an animal is fed with ROX, the As compounds in the manure primarily occur as ROX and its metabolites, including arsenate (As[V]), arsenite (As[III]), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA). Animal manure is commonly land applied with phosphorous fertilizers in China. A pot experiment was conducted to investigate the phytoavailability of ROX, As(V), As(III), MMA, and DMA in water spinach (Ipomoea aquatica), with the soil amended with 0, 0.25, 0.50, 1.0, and 2.0 g PO(4)/kg, respectively, plus 2% (w/w manure/soil) chicken manure (CM) bearing ROX and its metabolites. The results indicate that this species of water spinach cannot accumulate ROX and MMA at detectable levels, but As(V), As(III), and DMA were present in all plant samples. Increased phosphorous decreased the shoot As(V) and As(III) in water spinach but did not affect the root As(V). The shoot DMA and root As(III) and DMA were decreased/increased and then increased/decreased by elevated phosphorous. The total phosphorous content (P) in plant tissue did not correlate with the total As or the three As species in tissues. Arsenate, As(III), and DMA were more easily accumulated in the roots, and phosphate considerably inhibited their upward transport. Dimethylarsinic acid had higher transport efficiency than As(V) and As(III), but As(III) was dominant in tissues. Conclusively, phosphate had multiple effects on the accumulation and transport of ROX metabolites, which depended on their levels. However, proper utilization of phosphate fertilizer can decrease the accumulation of ROX metabolites in water spinach when treated with CM containing ROX and its metabolites. PMID:20821525

  19. Control of Photosynthetic Sucrose Synthesis by Fructose 2,6-Bisphosphate 1

    PubMed Central

    Stitt, Mark; Krzel, Birgit; Heldt, Hans W.

    1984-01-01

    The role of fructose 2,6 bisphosphate in partitioning of photosynthate between sucrose and starch has been studied in spinach (Spinacia oleracea U.S. hybrid 424). Spinach leaf material was pretreated to alter the sucrose content, so that the rate of starch synthesis could be varied. The level of fructose 2,6-bisphosphate and other metabolites was then related to the accumulation of sucrose and the rate of starch synthesis. The results show that fructose 2,6-bisphosphate is involved in a sequence of events which provide a fine control of sucrose synthesis so that more photosynthate is diverted into starch in conditions when sucrose has accumulated to high levels in the leaf tissue. (a) As sucrose levels in the leaf rise, there is an accumulation of triose phosphates and hexose phosphates, implying an inhibition of sucrose phosphate synthase and cytosolic fructose 1,6-bisphosphatase. (b) In these conditions, fructose 2,6-bisphosphate increases. (c) The increased fructose 2,6-bisphosphate can be accounted for by the increased fructose 6-phosphate in the leaf. (d) Fructose 2,6-bisphosphate inhibits the cytosolic fructose 1,6-bisphosphatase so more photosynthate is retained in the chloroplast, and converted to starch. PMID:16663665

  20. 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 ...

  1. Conversion of monogalactosyldiacylglycerols to triacylglycerols in ozone-fumigated spinach leaves. [Spinacia oleracea L

    SciTech Connect

    Sakaki, Takeshi; Saito, Kazuki; Kawaguchi, Akihiko; Kondo, Noriaki; Yamada, Mitsuhiro Keio Univ., Tokyo Univ. of Tokyo )

    1990-10-01

    Molecular species and fatty acid distribution of triacylglycerol (TG) accumulated in spinach (Spinacia oleracea L.) leaves fumigated with ozone (0.5 microliter per liter) were compared with those of monogalactosyldiacylglyerol (MGDG). Analysis of positional distribution of the fatty acids in MGDG and the accumulated TG by the enzymatic digestion method showed that hexadecatrienoate (16:3) was restricted to sn-2 position of the glycerol backbone in both MGDG and TG, whereas {alpha}-linolenate (18:3) was preferentially located at sn-1 position in MGDG, and sn-1 and/or sn-3 positions in TG, suggesting that 1,2-diacylglycerol moieties of MGDG are the direct precursor of TG in ozone-fumigated leaves. Further analysis of TG molecular species by argentation chromatography and mass spectrometry showed that TG increased with ozone fumigation consisted of approximately an equal molar ratio of sn-1,3-18:3-2-16:3 and sn-1,2,3-18:3. Because the molecular species of MGDG in spinach leaves is composed of a similar molar ratio of sn-1-18:3-2-16:3 and sn-1,2-18:3, we conducted that MGDG was converted to 1,2-diacylglycerol and acylated with 18:3 to TG in ozone-fumigated spinach leaves.

  2. Levels of (±) Abscisic Acid and Xanthoxin in Spinach under Different Environmental Conditions 1

    PubMed Central

    Zeevaart, Jan A. D.

    1974-01-01

    The levels of the growth inhibitors(+)-abscisic acid and xanthoxin were determined in the long day plant spinach (Spinacia oleracea L. cv. Savoy Hybrid 612) grown under different environmental conditions. When plants were transferred from light to darkness, the (+)-abscisic acid level always decreased, whereas the xanthoxin content did not change. The (+)-abscisic acid content was higher in plants grown under low than under high relative humidity. Xanthoxin levels were not affected by photoperiod, whereas the (+)-abscisic acid content increased 2 to 3 times upon transferring plants from short day to long day. Shoot tips with young leaves and mature leaves of the same plants analyzed separately did not differ in their inhibitor content when expressed per unit dry weight. No increase in xanthoxin level was observed in wilting plants. In general, the xanthoxin levels of spinach were much less affected by changes in the environment than were those of (+)-abscisic acid. In conclusion, there is no correlation between xanthoxin and (+)-abscisic acid levels in spinach on the one hand, and growth and flowering responses on the other. PMID:16658759

  3. Uptake, translocation, and transformation of pentachlorophenol in soybean and spinach plants

    SciTech Connect

    Casterline, J.L. Jr.; Barnett, N.M.; Ku, Y.

    1985-06-01

    Soybean plants were grown for 90 days and spinach plants for 64 days in a mixture of sterilized greenhouse soil and sand containing 10 ppm pentachlorophenol. All plant parts and soil samples were extracted and separated into nonpolar and polar fractions. Major nonpolar and polar metabolites were identified by gas-liquid chromatography and mass spectrometry. Nonpolar fractions from both soybean and spinach plants were found to contain pentachlorophenol and its metabolites, 2,3,4,6-tetrachlorophenol, methoxytetrachlorophenol, 2,3,4,6-tetrachloroanisole, and pentachloroanisole. Cleavage of polar metabolites from the soybean plants by acid hydrolysis yielded organic solvent-extractable products. These products were identified as pentachlorophenol, 2,3,4,6-tetrachlorophenol, and methoxytetrachlorophenol. Cleavage of polar materials from spinach plants yielded only pentachlorophenol. The polar metabolites from the soybean plants were also subjected to enzymatic cleavage by beta-glucosidase. The conjugates consisted mostly of O-glucosides of the same metabolites released by acid hydrolysis. Failure of hydrolysis by aryl sulfatase indicated that very little or no sulfates were present. The metabolites found in the plants were not detected in soil samples obtained from pots immediately after the plants were harvested.

  4. Conversion of Monogalactosyldiacylglycerols to Triacylglycerols in Ozone-Fumigated Spinach Leaves

    PubMed Central

    Sakaki, Takeshi; Saito, Kazuki; Kawaguchi, Akihiko; Kondo, Noriaki; Yamada, Mitsuhiro

    1990-01-01

    Molecular species and fatty acid distribution of triacylglycerol (TG) accumulated in spinach (Spinacia oleracea L.) leaves fumigated with ozone (0.5 microliter per liter) were compared with those of monogalactosyldiacylglycerol (MGDG). Analysis of positional distribution of the fatty acids in MGDG and the accumulated TG by the enzymatic digestion method showed that hexadecatrienoate (16:3) was restricted to sn-2 position of the glycerol backbone in both MGDG and TG, whereas ?-linolenate (18:3) was preferentially located at sn-1 position in MGDG, and sn-1 and/or sn-3 positions in TG, suggesting that 1,2-diacylglycerol moieties of MGDG are the direct precursor of TG in ozonefumigated leaves. Further analysis of TG molecular species by argentation chromatography and mass spectrometry showed that TG increased with ozone fumigation consisted of approximately an equal molar ratio of sn-1,3-18:3-2-16:3 and sn-1,2,3-18:3. Because the molecular species of MGDG in spinach leaves is composed of a similar molar ratio of sn-1-18:3-2-16:3 and sn-1,2-18:3, we concluded that MGDG was converted to 1,2-diacylglycerol and acylated with 18:3 to TG in ozone-fumigated spinach leaves. Images Figure 1 PMID:16667777

  5. Leaf conductance and carbon gain under salt-stressed conditions

    NASA Astrophysics Data System (ADS)

    Volpe, V.; Manzoni, S.; Marani, M.; Katul, G.

    2011-12-01

    Exposure of plants to salt stress is often accompanied by reductions in leaf photosynthesis and in stomatal and mesophyll conductances. To separate the effects of salt stress on these quantities, a model based on the hypothesis that carbon gain is maximized subject to a water loss cost is proposed. The optimization problem of adjusting stomatal aperture for maximizing carbon gain at a given water loss is solved for both a non-linear and a linear biochemical demand function. A key novel theoretical outcome of the optimality hypothesis is an explicit relationship between the stomatal and mesophyll conductances that can be evaluated against published measurements. The approaches here successfully describe gas-exchange measurements reported for olive trees (Olea europea L.) and spinach (Spinacia oleraceaL.) in fresh water and in salt-stressed conditions. Salt stress affected both stomatal and mesophyll conductances and photosynthetic efficiency of both species. The fresh water/salt water comparisons show that the photosynthetic capacity is directly reduced by 30%-40%, indicating that reductions in photosynthetic rates under increased salt stress are not due only to a limitation of CO2diffusion. An increase in salt stress causes an increase in the cost of water parameter (or marginal water use efficiency) exceeding 100%, analogous in magnitude to findings from extreme drought stress studies. The proposed leaf-level approach can be incorporated into physically based models of the soil-plant-atmosphere system to assess how saline conditions and elevated atmospheric CO2 jointly impact transpiration and photosynthesis.

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

    PubMed

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

    2015-01-01

    The extraction of lutein and β-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 β-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 β-carotene during UAE. Methanol extracts of leaves from spinach and authentic standards of lutein and β-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 β-carotene from spinach extracts. The resulting quadratic polynomial models for optimizing lutein and β-carotene from spinach had high coefficients of determination of 0.96 and 0.94, respectively. The optimal UAE settings for output of lutein and β-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 β-carotene for the dietary supplement industry. PMID:25875040

  7. Thiol modification and site directed mutagenesis of the flavin domain of spinach NADH:nitrate reductase.

    PubMed

    Trimboli, A J; Quinn, G B; Smith, E T; Barber, M J

    1996-07-01

    Incubation of either Chlorella nitrate reductase or the recombinant flavin domain of spinach nitrate reductase with reagents specific for modification of cysteine residues, such as N-ethylmaleimide, resulted in a time-dependent inactivation of NADH:ferricyanide reductase activity which could be prevented by incubation in the presence of NADH. At 25 degrees C and employing a fixed enzyme:modifier ratio, the rate of inactivation for both the Chlorella and spinach enzymes followed the order p-chloromercuribenzoate > methyl methanethiosulfonate > 2-(4'-maleimidylanilino)naphthalene-6-sulfonic acid > N-ethylmaleimide. For the spinach flavin domain, inactivation by methyl methanethiosulfonate or p-chloromercuribenzoate was found to be concentration independent suggesting the absence of nonspecific modifications. Initial rate studies of the methyl methanethiosulfonate-modified flavin domain indicated a reduction in NADH:ferricyanide activity (Vmax) from 85 to 44 micromol NADH consumed/min/nmol FAD and an increase in the Km for NADH from 12 to 35 microM when compared to the native enzyme, confirming a role for cysteine residue(s) in maintaining diaphorase activity. Site-directed mutagenesis of the four individual cysteines (residues 17, 54, 62, and 240) in the recombinant spinach flavin domain resulted in mutant proteins with visible and CD spectra very similar to those of the wild-type domain. Initial rate studies indicated that only substitutions of serine for cysteine 240 decreased diaphorase activity with maximal NADH:ferricyanide activity for the C240S mutant corresponding to 51 micromol NADH consumed/min/nmol FAD with a Km for NADH of 14 microM. Mutation of C240 to Ala or Gly resulted in greater loss of activity. The thermal stability of the four serine mutants was slightly decreased compared to the wild-type domain with the C62S mutant exhibiting the greatest instability. In contrast to the effects on diaphorase activity, square wave voltammetric studies indicated changes in the oxidation-reduction midpoint potential for the FAD/FADH2 couple in the C54S (E0'= -197 mV), C62S (E0' = -226 mV), and C240S (E0' = -219 mV) mutants compared to the wild-type domain (E0' = -268 mV). These results indicate that of the four cysteine residues in the spinach nitrate reductase flavin domain, only C240 plays a role in maintaining diaphorase activity, while C54 has the greatest influence on flavin redox potential and that no correlation between changes in catalytic activity and flavin redox potential was observed. PMID:8660690

  8. mRNA decay in spinach chloroplasts: psbA mRNA degradation is initiated by endonucleolytic cleavages within the coding region.

    PubMed Central

    Klaff, P

    1995-01-01

    The expression of chloroplast genes during leaf development in higher plants is regulated on several levels as transcription, RNA processing and stability, protein stability and turnover. Differential mRNA stability is one major component which contributes to the developmentally controlled accumulation of higher plant chloroplast psbA mRNA, which encodes the D1 protein of photosystem II. To understand the molecular mechanisms of specific mRNA degradation an in vitro mRNA decay system based on lysed chloroplasts from spinach leaves was established. Employing this degradation extract the decay of psbA mRNA was analyzed. Half-life of the psbA mRNA in vitro is dependent on the degradation conditions as the presence of Mg2+, which was found to stabilize the mRNA. Addition of tRNA stabilizes the mRNA and allows the accumulation of distinct degradation intermediates. psbA mRNA derived fragments of the same size were detected in degradation experiments in vitro, in organello and in vivo. 5' ends of the degradation intermediates were identified by primer extension and found to be localized in the 5' part of the coding region. The data indicate a degradation mechanism involving initiation of psbA mRNA decay by specific endonucleolytic cleavage and subsequent exonucleolytic degradation of the fragments. Possible models for cleavage site recognition are discussed. Images PMID:8532533

  9. Amino Acid and sucrose content determined in the cytosolic, chloroplastic, and vacuolar compartments and in the Phloem sap of spinach leaves.

    PubMed

    Riens, B; Lohaus, G; Heineke, D; Heldt, H W

    1991-09-01

    Amino acid and sucrose contents were analyzed in the chloroplastic, cytosolic, and vacuolar compartments and in the phloem sap of illuminated spinach leaves (Spinacia oleracea L.). The determination of subcellular metabolite distribution was carried out by nonaqueous fractionation of frozen and lyophilized leaf material using a novel three-compartment calculation method. The phloem sap was collected by aphid stylets which had been severed by a laser beam. Subcellular analysis revealed that the amino acids found in leaves are located mainly in the chloroplast stroma and in the cytosol, the sum of their concentrations amounting to 151 and 121 millimolar, respectively, whereas the amino acid concentrations in the vacuole are one order of magnitude lower. The amino acid concentrations in the phloem sap are found to be not very different from the cytosolic concentrations, whereas the sieve tube concentration of sucrose is found to be one order of magnitude higher than in the cytosol. It is concluded that the phloem loading results in a preferential extraction of sucrose from the source cells. PMID:16668375

  10. Assessment of microbial risk factors and impact of meteorological conditions during production of baby spinach in the Southeast of Spain.

    PubMed

    Castro-Ibáñez, I; Gil, M I; Tudela, J A; Ivanek, R; Allende, A

    2015-08-01

    There is a timely need to evaluate the effect agricultural factors and meteorological conditions on fresh produce contamination. This study evaluated those risk factors and described, for the first time, the distribution of indicator microorganisms (Escherichia coli, Enterococcus, coliforms, and Enterobacteriaceae) and the prevalence of foodborne pathogens (Enterohaemorrhagic E. coli, Listeria monocytogenes and Salmonella spp.) in baby spinach grown in the Southeast of Spain. A longitudinal study was conducted on three farms (2011-2013). Results obtained for E. coli highlighted soil and irrigation water as important factors affecting the microbial safety of baby spinach. Significant differences in the proportion of E. coli positive samples were found between treated (46.1%) and untreated (100%) irrigation water. However, the microbial quality of irrigation water didn't affect E. coli prevalence in produce. All E. coli positive spinach samples were detected at the highest observed temperature range suggesting that ambient temperature affects the probability and extent of spinach contamination. Salmonella spp. was detected by RT-PCR in manure, soil, irrigation water and baby spinach but only two of them (manure and irrigation water) were confirmed by isolation in culture media. Salmonella RT-PCR positive samples showed higher levels of E. coli than Salmonella negative samples. This preliminary finding supports recent identification of E. coli as a suitable parameter for the hygiene criterion at the primary production of leafy greens. PMID:25846928

  11. 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

  12. 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...

  13. 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...

  14. Changes in Chloroplast mRNA Stability during Leaf Development.

    PubMed Central

    Klaff, P; Gruissem, W

    1991-01-01

    During spinach leaf development, chloroplast-encoded mRNAs accumulate to different steady-state levels. Their relative transcription rates alone, however, cannot account for the changes in mRNA amount. In this study, we examined the importance of mRNA stability for the regulation of plastid mRNA accumulation using an in vivo system to measure mRNA decay in intact leaves by inhibiting transcription with actinomycin D. Decay of psbA and rbcL mRNAs was assayed in young and mature leaves. The psbA mRNA half-life was increased more than twofold in mature leaves compared with young leaves, whereas rbcL mRNA decayed with a similar relative half-life at both leaf developmental stages. The direct in vivo measurements demonstrated that differential mRNA stability in higher plant plastids can account for differences in mRNA accumulation during leaf development. The role of polysome association in mRNA decay was also investigated. Using organelle-specific translation inhibitors that force mRNAs into a polysome-bound state or deplete mRNAs of ribosomes, we measured mRNA decay in vivo in either state. The results showed that rbcL and psbA mRNAs are less stable when bound to polysomes relative to the polysome-depleted mRNAs and that their stabilities are differentially affected by binding to polysomes. The results suggested that ribosome binding and/or translation of the psbA and rbcL mRNAs may function to modulate the rate of their decay in chloroplasts. PMID:12324602

  15. Deer predation on leaf miners via leaf abscission

    NASA Astrophysics Data System (ADS)

    Yamazaki, Kazuo; Sugiura, Shinji

    2008-03-01

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

  16. Decreasing the NO3 and increasing the vitamin C contents in spinach by a nitrogen deprivation method.

    PubMed

    Mozafar, A

    1996-02-01

    Excessive use of nitrogen fertilizers is known to increase the NO3 and reduce the vitamin C contents in fruits and vegetables. We investigated the concentration of these compounds in spinach leaves when plants were transferred to nitrogen-free media prior to their harvest. It was noted that a pre-harvest transfer of spinach to N-free media reduces the NO3 and increases the vitamin C content of the leaves by a substantial amount in a 2-3 day period. It is suggested that this technique may be suited to produce spinach or other leafy vegetables with low NO3 and high vitamin C contents under commercial hydroponic conditions. PMID:8811729

  17. Reduction of Escherichia coli O157:H7 and Salmonella on baby spinach, using electron beam radiation.

    PubMed

    Neal, Jack A; Cabrera-Diaz, Elisa; Mrquez-Gonzlez, Mayra; Maxim, Joseph E; Castillo, Alejandro

    2008-12-01

    The effect of low-dose electron beam (e-beam) radiation on the reduction of Escherichia coli O157:H7 and Salmonella in spinach was studied. Fresh baby spinach (Spinacia oleracea) was inoculated with a bacterial cocktail containing multiple strains of rifampin-resistant E. coli O157:H7 and rifampin-resistant Salmonella. Inoculated samples were exposed to e-beam radiation from a linear accelerator and tested for counts of both E. coli O157:H7 and Salmonella. Irradiated spinach was also stored for 8 days at 4 degrees C, and counts were made at 2-day intervals to determine if there was any effect of radiation on the survival trend of both pathogens. When no pathogens were detected on plates, additional enrichment plating was conducted to verify total destruction. Respiration rates were measured on spinach samples exposed to e-beam radiation. Each dose of e-beam radiation significantly reduced the numbers of E. coli O157:H7 and Salmonella from initial levels of 7 log CFU/g. Treatment by e-beam radiation at a dose of 0.40 kGy resulted in a reduction in populations of E. coli O157:H7 and Salmonella of 3.7 and 3.4 log cycles, respectively. At 0.70 kGy, both pathogens were reduced by 4 log. All doses above 1.07 kGy showed reductions greater than 6 log and decreased to undetectable levels when stored for 8 days. The respiration rate of spinach showed no changes after irradiation up to 2.1 kGy. These results suggest that low-dose e-beam radiation may be a viable tool for reducing microbial populations or eliminating E. coli O157:H7 and Salmonella from spinach without product damage. PMID:19244893

  18. Biosynthesis and Desaturation of Prokaryotic Galactolipids in Leaves and Isolated Chloroplasts from Spinach 1

    PubMed Central

    Heemskerk, Johan W. M.; Schmidt, Hermann; Hammer, Ute; Heinz, Ernst

    1991-01-01

    Mono- and digalactosyldiacylglycerol (MGDG and DGDG) were isolated from the leaves of sixteen 16:3 plants. In all of these plant species, the sn-2 position of MGDG was more enriched in C16 fatty acids than sn-2 of DGDG. The molar ratios of prokaryotic MGDG to prokaryotic DGDG ranged from 4 to 10. This suggests that 16:3 plants synthesize more prokaryotic MGDG than prokaryotic DGDG. In the 16:3 plant Spinacia oleracea L. (spinach), the formation of prokaryotic galactolipids was studied both in vivo and in vitro. In intact spinach leaves as well as in chloroplasts isolated from these leaves, radioactivity from [1-14C]acetate accumulated 10 times faster in MGDG than in DGDG. After 2 hours of incorporation, most labeled galactolipids from leaves and all labeled galactolipids from isolated chloroplasts were in the prokaryotic configuration. Both in vivo and in vitro, the desaturation of labeled palmitate and oleate to trienoic fatty acids was higher in MGDG than in DGDG. In leaves, palmitate at the sn-2 position was desaturated in MGDG but not in DGDG. In isolated chloroplasts, palmitate at sn-2 similarly was desaturated only in MGDG, but palmitate and oleate at the sn-1 position were desaturated in MGDG as well as in DGDG. Apparently, palmitate desaturase reacts with sn-1 palmitate in either galactolipid, but does not react with the sn-2 fatty acid of DGDG. These results demonstrate that isolated spinach chloroplasts can synthesize and desaturate prokaryotic MGDG and DGDG. The finally accumulating molecular species, MGDG(18:3/16:3) and DGDG(18:3/16:0), are made by the chloroplasts in proportions similar to those found in leaves. PMID:16668143

  19. Thermal inactivation of human norovirus surrogates in spinach and measurement of its uncertainty.

    PubMed

    Bozkurt, Hayriye; D'souza, Doris H; Davidson, P Michael

    2014-02-01

    Leafy greens, including spinach, have potential for human norovirus transmission through improper handling and/or contact with contaminated water. Inactivation of norovirus prior to consumption is essential to protect public health. Because of the inability to propagate human noroviruses in vitro, murine norovirus (MNV-1) and feline calicivirus (FCV-F9) have been used as surrogates to model human norovirus behavior under laboratory conditions. The objectives of this study were to determine thermal inactivation kinetics of MNV-1 and FCV-F9 in spinach, compare first-order and Weibull models, and measure the uncertainty associated with the process. D-values were determined for viruses at 50, 56, 60, 65, and 72 C in 2-ml vials. The D-values calculated from the first-order model (50 to 72 C) ranged from 0.16 to 14.57 min for MNV-1 and 0.15 to 17.39 min for FCV-9. Using the Weibull model, the tD for MNV-1 and FCV-F9 to destroy 1 log (D ? 1) at the same temperatures ranged from 0.22 to 15.26 and 0.27 to 20.71 min, respectively. The z-values determined for MNV-1 were 11.66 0.42 C using the Weibull model and 10.98 0.58 C for the first-order model and for FCV-F9 were 10.85 0.67 C and 9.89 0.79 C, respectively. There was no difference in D- or z-value using the two models (P > 0.05). Relative uncertainty for dilution factor, personal counting, and test volume were 0.005, 0.0004, and ca. 0.84%, respectively. The major contribution to total uncertainty was from the model selected. Total uncertainties for FCV-F9 for the Weibull and first-order models were 3.53 to 7.56% and 11.99 to 21.01%, respectively, and for MNV-1, 3.10 to 7.01% and 13.14 to 16.94%, respectively. Novel and precise information on thermal inactivation of human norovirus surrogates in spinach was generated, enabling more reliable thermal process calculations to control noroviruses. The results of this study may be useful to the frozen food industry in designing blanching processes for spinach to inactivate or control noroviruses. PMID:24490922

  20. 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

  1. Characterization of a prokaryotic topoisomerase I activity in chloroplast extracts from spinach.

    PubMed

    Siedlecki, J; Zimmermann, W; Weissbach, A

    1983-03-11

    A topoisomerase I activity has been partially purified from crude extracts of spinach chloroplasts. This activity relaxes the supercoiled covalently closed circular DNA of pBR322. The enzyme requires Mg++, but not ATP, and has an apparent molecular weight of about 115,000. It catalyzes a unit change in the linkage number of supercoiled DNA but cannot relax positive supercoiled DNA. These characteristics of the topoisomerase suggest it is of the prokaryotic type and would tend to support the endosymbiotic theory of plastid origin and evolution. PMID:6298746

  2. Investigating the foliar uptake and within-leaf migration of phenanthrene by moss (Hypnum cupressiforme) using two-photon excitation microscopy with autofluorescence.

    PubMed

    Keyte, Ian; Wild, Edward; Dent, John; Jones, Kevin C

    2009-08-01

    Mosses have the potential to play a significant role in the global cycling and fate of semivolatile organic compounds (SVOCs), due to their extensive distribution at high latitudes and the long-range atmospheric transport of SVOCs. Unlike vascular plants mosses lack a substantial cuticle, vascular system, or root structure, taking up water, nutrients and SVOCs primarily from the atmosphere. Mosses have thus been effectively used as passive air samplers for many SVOCs in urban and rural locations. The potential differences in atmospheric uptake and within-leaf movement storage and processing of SVOCs between vascular and nonvascular living plants were investigated here by comparing the uptake and behavior of phenanthrene in spinach (Spinacia oleracea) and moss (Hypnum cupressiforme), using two-photon excitation microscopy coupled with autofluorescence. Chemical uptake, movement storage, and compartmentalization of phenanthrene was directly detected, visualized, and monitored over a 12 day period following exposure to gas phase phenanthrene. Species differences in the uptake of phenanthrene between moss and spinach leaves were observed, showing how morphological differences affect the foliar uptake of SVOCs. In spinach, phenanthrene accumulated within the cellular cytoplasm and vacuole. In moss, phenanthrene accumulated predominantly within the cell walls, before later migrating across the cell membrane into adjacent cells and the cellular cytoplasm. The study represents a further demonstration of how different plant species can display different and complex transport and storage pathways for the same chemical, and highlights the importance of the cellular structure and plant morphological and physiological features in controlling this behavior. PMID:19731673

  3. Active site histidine in spinach ribulosebisphosphate carboxylase/oxygenase modified by diethyl pyrocarbonate

    SciTech Connect

    Igarashi, Y.; McFadden, B.A.; el-Gul, T.

    1985-07-16

    (TH) Diethyl pyrocarbonate was synthesized from (TH) ethanol prepared by the reduction of acetaldehyde by NaB3H4. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) from spinach was inactivated with this reagent at pH 7.0 the presence of 20 mM MgS , and tryptic peptides that contained modified histidine residues were isolated by reverse-phase high-performance liquid chromatography. Labeling of the enzyme was conducted in the presence and absence of the competitive inhibitor sedoheptulose 1,7-bisphosphate. The amount of one peptide that was heavily labeled in the absence of this compound was reduced 10-fold in its presence. The labeled residue was histidine-298. This result, in combination with earlier experiments, suggests that His-298 in spinach RuBisCO is located in the active site domain and is essential to enzyme activity. This region of the primary structure is strongly conserved in seven other ribulosebisphosphate carboxylases from divergent sources.

  4. Topological studies of spinach 22 kDa protein of Photosystem II.

    PubMed

    Kim, S; Pichersky, E; Yocum, C F

    1994-12-30

    An intrinsic 22 kDa polypeptide is associated with the O2-evolving Photosystem II core complex in a variety of green plants, although it does not appear to be required for O2 evolution. Digestion of thylakoid membranes and isolated Photosystem II preparations with trypsin, followed by immunoblotting using spinach anti-22 kDa antibodies, leads to two observations: (1) the domain between the 2nd and 3rd transmembrane helices of the 22 kDa protein is stromally exposed, and (2) only in a reaction center complex preparation, lacking the chlorophyll a/b-light harvesting complex II, is there extensive proteolytic cleavage of the 22 kDa protein. We also found that after, but not prior to, selective extraction of the 22 and 10 kDa proteins from Photosystem II membranes, the chlorophyll a/b-light harvesting complex II can be separated from the Photosystem II reaction center core by precipitation with MgCl2. This result suggests that the 22 kDa polypeptide is located between the Photosystem II reaction center polypeptides and light-harvesting complex II; it is possible that the protein serves as a link between the two protein complexes. The presence of the 22 kDa protein in several species was also examined by immunoblotting with polyclonal spinach anti-22 kDa antibodies. PMID:7803450

  5. Ribosomes pause during the expression of the large ATP synthase gene cluster in spinach chloroplasts.

    PubMed Central

    Stollar, N E; Kim, J K; Hollingsworth, M J

    1994-01-01

    The large ATP synthase gene cluster from spinach (Spinacia oleracea) chloroplasts encodes five genes, the last four of which encode subunits of the ATP synthase complex. In preliminary experiments (J.K. Kim, M.J. Hollingsworth [1992] Anal Biochem 206: 183-188) it was shown that ribosomes pause during translation of these open reading frames. We have examined ribosome pausing in the four ATP synthase open reading frames of this gene cluster to determine whether it could affect the final ratio of the ATP synthase polypeptides derived from the cluster. Ribosome pauses were mapped and found to be distributed in a nonuniform manner. We have quantitated the relative extent of ribosome pausing within each open reading frame. There is a general but not absolute correlation between the extent of ribosomal pausing and the protein levels found within the ATP synthase complex. We conclude that although it is not the sole factor, ribosome pausing may be a significant posttranscriptional mechanism affecting the expression of the large ATP synthase gene cluster in spinach chloroplasts. PMID:7972492

  6. Restrictions to Carbon Dioxide Conductance and Photosynthesis in Spinach Leaves Recovering from Salt Stress

    PubMed Central

    Delfine, Sebastiano; Alvino, Arturo; Villani, Maria Concetta; Loreto, Francesco

    1999-01-01

    Salt accumulation in spinach (Spinacia oleracea L.) leaves first inhibits photosynthesis by decreasing stomatal and mesophyll conductances to CO2 diffusion and then impairs ribulose-1,5-bisphosphate carboxylase/oxygenase (S. Delfine, A. Alvino, M. Zacchini, F. Loreto [1998] Aust J Plant Physiol 25: 395402). We measured gas exchange and fluorescence in spinach recovering from salt accumulation. When a 21-d salt accumulation was reversed by 2 weeks of salt-free irrigation (rewatering), stomatal and mesophyll conductances and photosynthesis partially recovered. For the first time, to our knowledge, it is shown that a reduction of mesophyll conductance can be reversed and that this may influence photosynthesis. Photosynthesis and conductances did not recover when salt drainage was restricted and Na content in the leaves was greater than 3% of the dry matter. Incomplete recovery of photosynthesis in rewatered and control leaves may be attributed to an age-related reduction of conductances. Biochemical properties were not affected by the 21-d salt accumulation. However, ribulose-1,5-bisphosphate carboxylase/oxygenase activity and content were reduced by a 36- to 50-d salt accumulation. Photochemical efficiency was reduced only in 50-d salt-stressed leaves because of a decrease in the fraction of open photosystem II centers. A reduction in chlorophyll content and an increase in the chlorophyll a/b ratio were observed in 43- and 50-d salt-stressed leaves. Low chlorophyll affects light absorptance but is unlikely to change light partitioning between photosystems. PMID:10069849

  7. Effects of Pb 2+ on energy distribution and photochemical activity of spinach chloroplast

    NASA Astrophysics Data System (ADS)

    Wu, Xiao; Hong, Fashui; Liu, Chao; Su, Mingyu; Zheng, Lei; Gao, Fengqing; Yang, Fan

    2008-03-01

    Lead (Pb 2+) is a well-known highly toxic element. The mechanisms of the Pb 2+ toxicity are not well understood for photosynthesis. In this paper, we reported the effect of Pb 2+ on light absorption, distribution and conversion of spinach chloroplast by spectroscopy, and photochemical reaction activities. Several effects of Pb 2+ were observed: (1) the absorption peak intensity of chloroplast obviously decreased in red and blue region and produced optical flattering; (2) fluorescence quantum yield nearby 680 nm of chloroplast greatly declined; (3) the excitation band nearby 440 nm of chloroplast significantly descended; (4) Pb 2+ treatments reduced of the rate of whole chain electron transport, photochemical activities of PSII DCPIP photoreduction and oxygen evolution, but the photoreduction activities of PSI were little changed. Together, the studies of the experiments showed that Pb 2+ decreased absorption of light on spinach chloroplast and inhibited excitation energy to be absorbed by LHCII and transferred to PSII, then reduced the conversion from light energy to electron energy, and decelerated electron transport, water photolysis and oxygen evolution.

  8. Effects of Mg 2+on spectral characteristics and photosynthetic functions of spinach photosystem II

    NASA Astrophysics Data System (ADS)

    Liang, Chen; Xiao, Wu; Hao, Huang; Xiaoqing, Liu; Chao, Liu; Lei, Zheng; Fashui, Hong

    2009-03-01

    In the present paper we report the results obtained with the photosystem II (PSII) isolated from spinach treated by MgCl 2, and studied the effect of Mg 2+ on spectral characteristics and photosynthetic functions of PSII. The results showed that Mg 2+ treatment at a suitable concentration could significantly increase the absorption intensity of PSII and the intensity ratio of Soret band to Q band of chlorophyll-a. The treatment also elevated the excited peak intensity at 230, 278 and 343 nm, and the emitted peak intensity at 304 and 682 nm, and the ratio of F278/ F230, respectively. The results implied that Mg 2+ increased absorbance for visible light, improving energy transfer among amino acids within PSII protein complex and accelerating energy transport from tyrosine residue to chlorophyll-a. The photochemical activity and oxygen evolving rate of PSII were also enhanced by Mg 2+. This is viewed as evidence that Mg 2+ can promote energy transfer and oxygen evolution in PSII of spinach.

  9. Maple Leaf Outdoor Centre.

    ERIC Educational Resources Information Center

    Maguire, Molly; Gunton, Ric

    2000-01-01

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

  10. 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...

  11. Maple Leaf Outdoor Centre.

    ERIC Educational Resources Information Center

    Maguire, Molly; Gunton, Ric

    2000-01-01

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

  12. Raspberry leaf curl virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  13. PLATYSPORA LEAF SPOT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Platyspora leaf spot, caused by Comoclathris pentamera (P. Karst.) S. Ahmad (= Graphyllium pentamerum (P. Karst.) M.E. Barr; = Platyspora pentamera (P. Karst.) Wehm.) was first reported as a plant disease on wheat in 1971. The fungus previously was known only at high altitudes, where it persists on...

  14. Comparative survival of Escherichia coli O157:H7, Salmonella Typhimurium, and Murine Norovirus on spinach plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: Outbreaks resulting from the consumption of leafy greens contaminated with E. coli O157:H7, Salmonella spp., and norovirus have occurred. It is unclear how the stress response factor rpoS in E. coli O157:H7 and Salmonella spp. affects their survival on spinach. Purpose: A comparison ...

  15. 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

  16. Effects of extraction and high-performance liquid chromatographic conditions on the determination of lutein in spinach.

    PubMed

    Simonovska, Breda; Vovk, Irena; Glavnik, Vesna; Cernelič, Katarina

    2013-02-01

    A major factor in the direct determination of lutein in spinach extracts proved to be obtaining reproducible and stable chromatography of lutein. This was achieved on a C30 column with the mobile phase acetone-0.1M triethylammonium acetate (TEAA) buffer (pH 7) 9:1 (v/v). Extraction of 10mg of lyophilized spinach with 10 mL of extraction solvent (ethanol, acetone, ethanol-ethyl acetate 1:1 (v/v), methanol-THF 1:1 (v/v)) for 15 min with magnetic stirring under nitrogen resulted in equal yields of lutein. The yields were enhanced by addition of 15% of 1M TEAA buffer pH 7 to all four extraction solvents. As confirmed by recovery experiments, no loss of lutein occurred during the extraction. The relative standard deviation from triplicate extractions was less than 5%. The addition of 15% TEAA pH 7 to acetone enhanced the extraction yield of lutein also from unlyophilized spinach. The content of lutein in different spinach samples ranged from 5 to 15 mg/100g of fresh weight. The first separation is reported of all the carotenoids and chlorophylls on a C18 core-shell column and the addition of 15% of 1M TEAA buffer pH 7 to acetone also enhanced the extraction yield of β-carotene compared to the yield produced by pure acetone. PMID:23312861

  17. Chimaeric CP47 mutants of the cyanobacterium Synechocystis sp. PCC 6803 carrying spinach sequences: Construction and function.

    PubMed

    Vermaas, W F; Shen, G; Ohad, I

    1996-05-01

    Chimaeric mutants of the cyanobacterium Synechocystis sp. PCC 6803 have been generated carrying part or all of the spinach psbB gene, encoding CP47 (one of the chlorophyll-binding core antenna proteins in Photosystem II). The mutant in which the entire psbB gene had been replaced by the homologous gene from spinach was an obligate photoheterotroph and lacked Photosystem II complexes in its thylakoid membranes. However, this strain could be transformed with plasmids carrying selected regions of Synechocystis psbB to give rise to photoautotrophs with a chimaeric spinach/cyanobacterial CP47 protein. This process involved heterologous recombination in the cyanobacterium between psbB sequences from spinach and Synechocystis 6803; which was found to be reasonably effective in Synechocystis. Also other approaches were used that can produce a broad spectrum of chimaeric mutants in a single experiment. Functional characterization of the chimaeric photoautotrophic mutants indicated that if a decrease in the photoautotrophic growth rates was observed, this was correlated with a decrease in the number of Photosystem II reaction centers (on a chlorophyll basis) in the thylakoid membrane and with a decrease in oxygen evolution rates. Remaining Photosystem II reaction centers in these chimaeric mutants appeared to function rather normally, but thermoluminescence and chlorophyll a fluorescence measurements provided evidence for a destabilization of QB (-). This illustrates the sensitivity of the functional properties of the PS II reaction center to mild perturbations in a neighboring protein. PMID:24271295

  18. 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,...

  19. 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 ...

  20. Escherichia coli O157:H7 in Feral Swine near Spinach Fields and Cattle, Central California Coast1

    PubMed Central

    Cooley, Michael; Carychao, Diana; Wiscomb, Gerald W.; Sweitzer, Richard A.; Crawford-Miksza, Leta; Farrar, Jeff A.; Lau, David K.; OConnell, Janice; Millington, Anne; Asmundson, Roderick V.; Atwill, Edward R.; Mandrell, Robert E.

    2007-01-01

    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

  1. 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.

  2. Effect of surface characteristics on retention and removal of Escherichia coli O157:H7 on surfaces of spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The topography and the spatial heterogeneity of produce surfaces may impact the attachment of microbial cells onto produce surfaces and affect disinfection efficacy. In this study, the effects of produce surface characteristics on the removal of bacteria were studied. Fresh spinach leaves were sp...

  3. Inactivation of Escherichia coli O157:H7 in vitro and on the surface of spinach leaves by biobased surfactants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to evaluate the effect of biosurfactants on the populations of Escherichia coli O157:H7 in suspension and on spinach leaves. Eight surfactants including four soybean oil-based biosurfactants, sodium dodecyl sulfate (SDS), polyoxyethylene sorbitan monooleate (Tween 80), sopho...

  4. Survival and transfer of murine norovirus 1, a surrogate for human noroviruses, during the production process of deep-frozen onions and spinach.

    PubMed

    Baert, Leen; Uyttendaele, Mieke; Vermeersch, Mattias; Van Coillie, Els; Debevere, Johan

    2008-08-01

    The reduction of murine norovirus 1 (MNV-1) on onions and spinach by washing was investigated as was the risk of contamination during the washing procedure. To decontaminate wash water, the industrial sanitizer peracetic acid (PAA) was added to the water, and the survival of MNV-1 was determined. In contrast to onions, spinach undergoes a heat treatment before freezing. Therefore, the resistance of MNV-1 to blanching of spinach was examined. MNV-1 genomic copies were detected with a real-time reverse transcription PCR assay in PAA-treated water and blanched spinach, and PFUs (representing infectious MNV-1 units) were determined with a plaque assay. A < or = 1-log reduction in MNV-1 PFUs was achieved by washing onion bulbs and spinach leaves. More than 3 log PFU of MNV-1 was transmitted to onion bulbs and spinach leaves when these vegetables were washed in water containing approximately 5 log PFU/ml. No decline of MNV-1 occurred in used industrial spinach wash water after 6 days at room temperature. A concentration of 20 ppm of PAA in demineralized water (pH 4.13) and in potable water (pH 7.70) resulted in reductions of 2.88 +/- 0.25 and 2.41 +/- 0.18 log PFU, respectively, after 5 min of exposure, but no decrease in number of genomic copies was observed. No reduction of MNV-1 PFUs was observed on frozen onions or spinach during storage for 6 months. Blanching spinach (80 degrees C for 1 min) resulted in at least 2.44-log reductions of infectious MNV-1, but many genomic copies were still present. PMID:18724752

  5. 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 10 ppmv) and aerosolized peracetic acid (PAA) (80 ppm) were applied alone or in combination for 20 min. Exposure to 10 ppmv of ClO2 gas for 20 min 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 80 ppm of aerosolized PAA for 20 min 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 (10 ppmv) and aerosolized PAA (80 ppm) for 20 min 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 (10 ppmv) and aerosolized PAA (80 ppm) did not significantly (p>0.05) affect the color and texture of samples during 7 days of storage. PMID:26001524

  6. 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

  7. Altered utilization of N-acetyl-D-galactosamine by Escherichia coli O157:H7 from the 2006 spinach outbreak.

    PubMed

    Mukherjee, Amit; Mammel, Mark K; LeClerc, J Eugene; Cebula, Thomas A

    2008-03-01

    In silico analyses of previously sequenced strains of Escherichia coli O157:H7, EDL933 and Sakai, localized the gene cluster for the utilization of N-acetyl-D-galactosamine (Aga) and D-galactosamine (Gam). This gene cluster encodes the Aga phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) and other catabolic enzymes responsible for transport and catabolism of Aga. As the complete coding sequences for enzyme IIA (EIIA)(Aga/Gam), EIIB(Aga), EIIC(Aga), and EIID(Aga) of the Aga PTS are present, E. coli O157:H7 strains normally are able to utilize Aga as a sole carbon source. The Gam PTS complex, in contrast, lacks EIIC(Gam), and consequently, E. coli O157:H7 strains cannot utilize Gam. Phenotypic analyses of 120 independent isolates of E. coli O157:H7 from our culture collection revealed that the overwhelming majority (118/120) displayed the expected Aga+ Gam- phenotype. Yet, when 194 individual isolates, derived from a 2006 spinach-associated E. coli O157:H7 outbreak, were analyzed, all (194/194) displayed an Aga- Gam- phenotype. Comparison of aga/gam sequences from two spinach isolates with those of EDL933 and Sakai revealed a single nucleotide change (G:C-->A:T) in the agaF gene in the spinach-associated isolates. The base substitution in agaF, which encodes EIIA(Aga/Gam) of the PTS, changes a conserved glycine residue to serine (Gly91Ser). Pyrosequencing of this region showed that all spinach-associated E. coli O157:H7 isolates harbored this same G:C-->A:T substitution. Notably, when agaF+ was cloned into an expression vector and transformed into six spinach isolates, all (6/6) were able to grow on Aga, thus demonstrating that the Gly91Ser substitution underlies the Aga- phenotype in these isolates. PMID:18156259

  8. Altered Utilization of N-Acetyl-d-Galactosamine by Escherichia coli O157:H7 from the 2006 Spinach Outbreak?

    PubMed Central

    Mukherjee, Amit; Mammel, Mark K.; LeClerc, J. Eugene; Cebula, Thomas A.

    2008-01-01

    In silico analyses of previously sequenced strains of Escherichia coli O157:H7, EDL933 and Sakai, localized the gene cluster for the utilization of N-acetyl-d-galactosamine (Aga) and d-galactosamine (Gam). This gene cluster encodes the Aga phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) and other catabolic enzymes responsible for transport and catabolism of Aga. As the complete coding sequences for enzyme IIA (EIIA)Aga/Gam, EIIBAga, EIICAga, and EIIDAga of the Aga PTS are present, E. coli O157:H7 strains normally are able to utilize Aga as a sole carbon source. The Gam PTS complex, in contrast, lacks EIICGam, and consequently, E. coli O157:H7 strains cannot utilize Gam. Phenotypic analyses of 120 independent isolates of E. coli O157:H7 from our culture collection revealed that the overwhelming majority (118/120) displayed the expected Aga+ Gam? phenotype. Yet, when 194 individual isolates, derived from a 2006 spinach-associated E. coli O157:H7 outbreak, were analyzed, all (194/194) displayed an Aga? Gam? phenotype. Comparison of aga/gam sequences from two spinach isolates with those of EDL933 and Sakai revealed a single nucleotide change (G:C?A:T) in the agaF gene in the spinach-associated isolates. The base substitution in agaF, which encodes EIIAAga/Gam of the PTS, changes a conserved glycine residue to serine (Gly91Ser). Pyrosequencing of this region showed that all spinach-associated E. coli O157:H7 isolates harbored this same G:C?A:T substitution. Notably, when agaF+ was cloned into an expression vector and transformed into six spinach isolates, all (6/6) were able to grow on Aga, thus demonstrating that the Gly91Ser substitution underlies the Aga? phenotype in these isolates. PMID:18156259

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

    PubMed

    Maruthachalam, Karunakaran; Klosterman, Steven J; Anchieta, Amy; Mou, Beiquan; Subbarao, Krishna V

    2013-03-01

    Verticillium wilt on spinach (Spinacia oleracea) is caused by the soilborne fungus Verticillium dahliae. The pathogen is seedborne and transmission through seed is a major concern because of the dispersal of the pathogen to areas where fresh and processing spinach crops are grown in rotation with susceptible crops. Reduction in seedborne inoculum minimizes pathogen spread; therefore, knowledge of pathogen localization in seed is critical to develop methods to reduce seedborne inoculum. Spinach seedlings were inoculated with conidial suspensions of a green fluorescent protein-tagged strain of V. dahliae and colonization events were followed through seed production by confocal laser-scanning microscopy. Between 24 to 96 h postinoculation (PI), conidia germinated and formed hyphal colonies on root tips and in root elongation zones. Hyphae colonized root cortical tissues both intra and intercellularly by 2 weeks, and colonized the taproot xylem with abundant mycelia and conidia that led to vascular discoloration coincident with foliar symptom expression by 8 weeks PI. At 10 weeks PI, the xylem of the upper stem, inflorescence, and spinach seed parts, including the pericarp, seed coat, cotyledons, and radicle, had been colonized by the pathogen but not the perisperm (the diploid maternal tissue). Maximum concentration of the fungus was in the seed coat, the outermost layer of the vasculature. Infection of V. dahliae in spinach seed was systemic and transmissible to developing seedlings. Additional analyses indicated that fungicide and steam seed treatments reduced detectable levels of the pathogen but did not eliminate the pathogen from the seed. This information will assist in the development of seed treatments that will reduce the seedborne inoculum transmission to crop production fields. PMID:23190117

  10. Effect of home processing on total and extractable calcium and zinc content of spinach (Spinach oleracia) and amaranth (Amaranthus tricolor) leaves.

    PubMed

    Yadav, S K; Sehgal, S

    1995-07-01

    Spinach (Spinacia oleracia) and amaranth (Amaranthus tricolor) leaves were stored in polyethylene bags and without packing for 24 and 48 hours in a refrigerator at 5 and 30 degrees C in polyethylene bags. The fresh leaves were also dried (oven and sun); blanched (5, 10 and 15 min) and cooked in an open pan and a pressure cooker. The processed leaves were analysed for total and extractable calcium and zinc content. The Ca and Zn content of these leaves varied from 1320 to 2120 and 11.70 to 12.60 mg/100 g DM and the percentage HCl-extractability was 77.82 to 81.92 and 85.16 to 86.15, respectively. No significant effects of drying and storage were observed on total Ca and Zn content and HCl-extractability while blanching and cooking resulted in significant improvement of HCl-extractability of these two minerals. Thus, cooking and blanching are good ways to improve the HCl-extractability of Ca and Zn. PMID:8719740

  11. Gibberellin A[sub 1] is required for stem elongation in spinach

    SciTech Connect

    Zeevaart, J.A.D.; Gage, D.A.; Talon, M. )

    1993-08-01

    The effects of the growth retardants 2'-isopropyl-4'-(trimethylammonium chloride)-5'-methylphenyl piperidine-1-carboxylate (AMO-1618) and calcium 3,5-dioxo-4-propionylcyclohexanecarboxylate (BX-112) on stem elongation were investigated in the rosette plant spinach (Spinacia oleracea L.) under long-day (LD) conditions. Stem growth induced by a LD treatment was prevented by both retardants. The inhibition caused by AMO-1618 was reversed by gibberellin A[sub 1] (GA[sub 1]) and GA[sub 20], whereas the effects of BX-112 were reversed by GA[sub 1] only. Six GAs (GA[sub 53], GA[sub 44], GA[sub 19], GA[sub 20], GA[sub 1], and GA[sub 8]) were quantified by gas chromatography-selected ion monitoring using internal standards. Plants treated with BX-112 had reduced levels of GA[sub 1], and GA[sub 8] and accumulated GA[sub 53], GA[sub 44], GA[sub 19], and GA[sub 20]. The relative levels of four additional GAs (3-epi-GA[sub 1], GA[sub 29], GA[sub 60], and GA[sub 81]) were compared by ion intensities only. Relative to GA[sub 81], the level of GA[sub 29] was decreased by BX-112, whereas the levels of GA[sub 6] and 3-epi-GA[sub 1] were increased. Transfer of spinach from short-day conditions to LD conditions caused an increase in all identified GAs of the early 13-hydroxylation pathway with GA[sub 20], GA[sub 1], and GA[sub 8] showing the largest increases. These findings support the position that, of the GA[sub s] belonging to the early 13-hydroxylation pathway, GA[sub 1] is the primary GA active per se for stem elongation in spinach. The increase in endogenous GA[sub 1] in plants in LD conditions is most likely the primary factor for stem elongation. 23 refs., 7 figs., 3 tabs.

  12. 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.

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

    SciTech Connect

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

    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.

  14. Temperature dependent steady state and picosecond kinetic fluorescence measurements of a photosystem I preparation from spinach

    SciTech Connect

    Mukerji, I.; Sauer, K.

    1988-08-01

    The fluorescence properties of a photosystem I (PSI) preparation from spinach containing approximately 200 chlorophyll (Chl) per reaction center were investigated. The preparation, characterized both spectroscopically and biochemically, contained the peripheral light harvesting antenna associated with PSI. In this study steady state fluorescence measurements were performed as a function of temperature. An emission maximum at 690 nm and a long wavelength shoulder from 710 to 740 nm were observed. The fluorescence yield at 690 nm is temperature independent, while the yield of the long wavelength shoulder increases dramatically with decreasing temperature. Additionally, kinetic measurements using the technique of single photon counting were done at room temperature and 77K. At 295K a four component fit was needed to describe the fluorescence decay; whereas at 77K, an additional 40-50 ps rise component indicative of fluorescence induction was necessary. 28 refs., 13 figs., 1 tab.

  15. Electron spin resonance studies of urea-ferricyanide inactivated spinach photosystem I particles

    SciTech Connect

    Golbeck, J.H.; Warden, J.T.

    1981-09-01

    The photosystem I acceptor system of a subchloroplast particle from spinach was investigated by optical and electron spin resonance (ESR) spectroscopy following graduated inactivation of the bound iron-sulfur proteins by urea-ferricyanide. The chemical analysis of iron and sulfur and the ESR properties of centers A, B, and X are consistent with the participation of three iron-sulfur centers in photosystem I. A differential decrease in centers A, B, and X is observed under conditions which induce S= ..-->.. S/sup 0/ conversion in the bound iron-sulfur proteins. Center B is shown to be the most susceptible, while center X is the least susceptible component to oxidative denaturation. Stepwise inactivation experiments suggest that electron transport in photosystem I does not occur sequentially from X ..-->.. B ..-->.. A since there is quantitative photoreduction of center A in the absence of center B. We propose that center A is directly reduced by X.

  16. Contribution of vitamin K1 to the electron spin polarization in spinach photosystem I

    SciTech Connect

    Rustandi, R.R.; Snyder, S.W.; Feezel, L.L.; Michalski, T.J.; Norris, J.R.; Thurnauer, M.C.; Biggins, J. )

    1990-09-04

    The electron spin polarized (ESP) electron paramagnetic resonance (EPR) signal observed in spinach photosystem I (PSI) particles was examined in preparations depleted of vitamin K1 by solvent extraction and following biological reconstitution by the quinone. The ESP EPR signal was not detected in the solvent-extracted PSI sample but was restored upon reconstitution with either protonated or deuterated vitamin K1 under conditions that also restored electron transfer to the terminal PSI acceptors. Reconstitution using deuterated vitamin K1 resulted in a line narrowing of the ESP EPR signal, supporting the conclusion that the ESP EPR signals in the reconstituted samples arise from a radical pair consisting of the oxidized PSI primary donor, P700+, and reduced vitamin K1.

  17. Characterization of elemental sulfur in isolated intact spinach chloroplasts. [Spinacia oleracea L

    SciTech Connect

    Joyard, J.; Douce, R. ); Forest, E. ); Blee, E. )

    1988-12-01

    Incubation of intact spinach (Spinacia oleracea L.) chloroplasts in the presence of {sup 35}SO{sub 4}{sup 2{minus}} resulted in the light-dependent formation of a chloroform-soluble sulfur-containing compound distinct from sulfolipid. The authors have identified this compound as the most stable form (S{sub 8}) of elemental sulfur (S{sup 0}, valence state for S = O) by mass spectrometry. It is possible that elemental sulfur (S{sup 0}) was formed by oxidation of bound sulfide, i.e. after the photoreduction of sulfate to sulfide by intact chloroplasts, and released as S{sub 8} under the experimental conditions used for analysis.

  18. 15-cis-beta-carotene found in the reaction center of spinach photosystem II.

    PubMed

    Bialek-Bylka, G E; Tomo, T; Satoh, K; Koyama, Y

    1995-04-17

    Solvent extraction at approximately 4 degrees C in complete darkness, and subsequent analysis by high-pressure liquid chromatography (at approximately 4 degrees C) using an apparatus equipped with a two-dimensional diode-array detector, spectroscopically identified 15-cis-beta-carotene in the reaction center (RC) of spinach photosystem II (PS II). The result revises a previous conclusion that beta-carotene bound to the PS II RC takes the all-trans configuration [Fujiwara, H., Hayashi, H., Tasumi, M., Kanaji, M., Koyama, Y. and Satoh, K. (1987) Chem. Lett. 2005-2008], and generalizes the concept established for purple photosynthetic bacteria that 15-cis-carotenoid is naturally selected by the photosynthetic reaction centers. PMID:7729534

  19. 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 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. PMID:25875029

  20. Phosphatidylglycerol Synthesis in Spinach Chloroplasts: Characterization of the Newly Synthesized Molecule

    PubMed Central

    Sparace, Salvatore A.; Mudd, J. Brian

    1982-01-01

    Intact chloroplasts from spinach (Spinacia oleracea L., hybrid 424) readily incorporate [14C]glycerol-3-phosphate and [14C]acetate into diacylglycerol, monoacylglycerol, diacylglycrol, free fatty acids (only when acetate is the precursor), phosphatidic acid, phosphatidylcholine, and most notably phosphatidylglycerol. The fraction of phosphatidylglycerol synthesized is greatly increased by the presence of manganese chloride in the reaction mixture. Glycerol-3-phosphate-labeled phosphatidylglycerol is equally labeled in the two glycerol moieties of the molecule. Acetate-labeled phosphatidylglycerol is equally labeled in both acyl groups. Position one contains primarily oleate, linoleate and small amounts of palmitate. Position two contains primarily palmitate. No radioactive trans-?3-hexadecenoate was detected. The labeling patterns indicate that the radioactive phosphatidylglycerol is the product of de novo chloroplast lipid biosynthesis and furthermore, phosphatidylglycerol may be a substrate for fatty acid desaturation. Images Fig. 1 PMID:16662664

  1. Combining Spinach-tagged RNA and gene localization to image gene expression in live yeast

    PubMed Central

    Guet, David; Burns, Laura T.; Maji, Suman; Boulanger, Jérôme; Hersen, Pascal; Wente, Susan R.; Salamero, Jean; Dargemont, Catherine

    2015-01-01

    Although many factors required for the formation of export-competent mRNPs have been described, an integrative view of the spatiotemporal coordinated cascade leading mRNPs from their site of transcription to their site of nuclear exit, at a single cell level, is still partially missing due to technological limitations. Here we report that the RNA Spinach aptamer is a powerful tool for mRNA imaging in live S. cerevisiae with high spatial-temporal resolution and no perturbation of the mRNA biogenesis properties. Dedicated image processing workflows are developed to allow detection of very low abundance of transcripts, accurate quantitative dynamic studies, as well as to provide a localization precision close to 100 nm at consistent time scales. Combining these approaches has provided a state-of-the-art analysis of the osmotic shock response in live yeast by localizing induced transcription factors, target gene loci and corresponding transcripts. PMID:26582123

  2. Combining Spinach-tagged RNA and gene localization to image gene expression in live yeast.

    PubMed

    Guet, David; Burns, Laura T; Maji, Suman; Boulanger, Jérôme; Hersen, Pascal; Wente, Susan R; Salamero, Jean; Dargemont, Catherine

    2015-01-01

    Although many factors required for the formation of export-competent mRNPs have been described, an integrative view of the spatiotemporal coordinated cascade leading mRNPs from their site of transcription to their site of nuclear exit, at a single cell level, is still partially missing due to technological limitations. Here we report that the RNA Spinach aptamer is a powerful tool for mRNA imaging in live S. cerevisiae with high spatial-temporal resolution and no perturbation of the mRNA biogenesis properties. Dedicated image processing workflows are developed to allow detection of very low abundance of transcripts, accurate quantitative dynamic studies, as well as to provide a localization precision close to 100 nm at consistent time scales. Combining these approaches has provided a state-of-the-art analysis of the osmotic shock response in live yeast by localizing induced transcription factors, target gene loci and corresponding transcripts. PMID:26582123

  3. Investigation of detergent effects on the solution structure of spinach Light Harvesting Complex II

    NASA Astrophysics Data System (ADS)

    Cardoso, Mateus B.; Smolensky, Dmitriy; Heller, William T.; O'Neill, Hugh

    2010-11-01

    The properties of spinach light harvesting complex II (LHC II), stabilized in the detergents Triton X-100 (TX100) and n-Octyl-β-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.

  4. Fabrication of Organic Light-Emitting Diodes Using Photosynthetic Pigments Extracted from Spinach

    NASA Astrophysics Data System (ADS)

    Ohtani, Naoki; Kitagawa, Natsuko; Matsuda, Takashi

    2011-01-01

    We fabricated organic light-emitting diodes (OLEDs) containing chlorophylls in the active region, which were extracted from spinach using a chemical method. Photoluminescence (PL) cannot be observed in the thin film of the extracted chlorophylls owing to concentration quenching. To overcome the concentration quenching, a host material, poly[(m-phenylenevinylene)-alt-(2,5-dihexyloxy-p-phenylenevinylene)] (PPV) was added in the active region. This leads to the observaton of electroluminescence (EL) signals originating from chlorophyll a. We also evaluated the lifetime of the PL and EL. Consequently, the OLEDs containing carotenoids in the active region exhibit the light-emission much longer time than that without carotenoidos. This is assigned to the antioxidant activities of carotenoids. OLEDs containing a large amount of carotenoids are resistant to the oxidation damage.

  5. 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.

  6. The role of glycinebetaine in the protection of spinach thylakoids against freezing stress.

    PubMed

    Coughlan, S J; Heber, U

    1982-11-01

    The quaternary ammonium compound glycinebetaine has been tested for cryoprotective properties, using isolated spinach thylakoids as a model membrane system. The effect of a 3-h,-20C freezing regime on different photosynthetic parameters was measured. These parameters were the light-stimulated ?pH formation and dark ?pH decay, light-stimulated proton uptake, electron flow through photosystem II, photosystem I and total linear electron flow, and pyocyanine-mediated cyclic photophosphorylation. It was shown that below 100 mM glycinebetaine was superior as a cryoprotectant to sucrose on a molar, a molal and an activity basis. At higher concentrations, glycinebetaine was less efficient in preventing inactivation of thylakoids during freezing than sucrose. These observations are discussed in relation to the permeability of biomembranes to glycinebetaine and the colligative theory of cryoprotection. It is concluded that colligative protection is modified by direct interaction between cryoprotectant and membranes. PMID:24272216

  7. Probing the donor side of photosystem II in spinach chloroplasts and algae using electron paramagnetic resonance

    SciTech Connect

    Boska, M.D.

    1985-11-01

    this work concerns electron transfer reactions in photosystem II (PS II). Investigations carried out in this work examine the redox reaction rates in PS II using EPR. In Tris-washed PS II preparations from spinach, it is observed that the oxidation kinetics of S II/sub f/, the EPR signal formed by Z/sup +/ after deactivation of oxygen evolution, mirror the reduction kinetics of P680/sup +/ seen by EPR in samples poised at a variety of pH's. These data agree with previous data on the optically measured reduction kinetics of P680/sup +/. The oxidation kinetics of S II/sub vf/, the EPR transient seen from Z/sup +/ in samples active in O/sub 2/ evolving samples, were instrument limited (t/sub 1/2/ less than 4 ..mu..s) and thus could not be directly measured. These results taken together support a model where Z donates electrons directly to P680/sup +/. The examination of the oxidation and reduction kinetics of S II in monovalent and divalent salt-washed PS II preparations from spinach correlated most of the change of Z oxidation and re-reduction kinetics seen upon Tris-treatment with the loss of a 33 kDa polypeptide associated with the donor side of PS II. These data coupled with observations of stead-state light-induced amplitude changes in S II give evidence for the existance of an electron carrier between the water-splitting enzyme and Z. Observation of S II amplitude and kinetics in highly resolved PS II protein complexes from Synechoccus sp., consisting of either a 5 polypeptide PS II core complex (E-1) or a 4 polypeptide PS II core complex (CP2b), localize Z and P680 within the 4 polypeptide complex. 187 refs., 17 figs., 7 tabs.

  8. Signal transduction in leaf senescence.

    PubMed

    Zhang, Haoshan; Zhou, Chunjiang

    2013-08-01

    Leaf senescence is a complex developmental phase that involves both degenerative and nutrient recycling processes. It is characterized by loss of chlorophyll and the degradation of proteins, nucleic acids, lipids, and nutrient remobilization. The onset and progression of leaf senescence are controlled by an array of environmental cues (such as drought, darkness, extreme temperatures, and pathogen attack) and endogenous factors (including age, ethylene, jasmonic acid, salicylic acid, abscisic acid, and cytokinin). This review discusses the major breakthroughs in signal transduction during the onset of leaf senescence, in dark- and drought-mediated leaf senescence, and in various hormones regulating leaf senescence achieved in the past several years. Various signals show different mechanisms of controlling leaf senescence, and cross-talks between different signaling pathways make it more complex. Key senescence regulatory networks still need to be elucidated, including cross-talks and the interaction mechanisms of various environmental signals and internal factors. PMID:23096425

  9. The worldwide leaf economics spectrum.

    PubMed

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

    2004-04-22

    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 type or biome. Categories along the spectrum would, in general, describe leaf economic variation at the global scale better than plant functional types, because functional types overlap substantially in their leaf traits. Overall, modulation of leaf traits and trait relationships by climate is surprisingly modest, although some striking and significant patterns can be seen. Reliable quantification of the leaf economics spectrum and its interaction with climate will prove valuable for modelling nutrient fluxes and vegetation boundaries under changing land-use and climate. PMID:15103368

  10. Leaf development: a cellular perspective.

    PubMed

    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. Leaf development: a cellular perspective

    PubMed Central

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

    2014-01-01

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

  12. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  13. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  14. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  15. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  16. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  17. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  18. 7 CFR 29.3033 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture Regulations... Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  19. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  20. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  1. 7 CFR 29.2528 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture Regulations...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  2. 7 CFR 29.3525 - Leaf.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture Regulations... Type 95) 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  3. 7 CFR 29.1028 - Leaf.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture Regulations... Type 92) 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip form, shall describe the divided unit of a whole leaf....

  4. The broad spectrum 2-oxoglutarate oxygenase inhibitor N-oxalylglycine is present in rhubarb and spinach leaves.

    PubMed

    Al-Qahtani, Khalid; Jabeen, Bushra; Sekirnik, Rok; Riaz, Naheed; Claridge, Timothy D W; Schofield, Christopher J; McCullagh, James S O

    2015-09-01

    2-Oxoglutarate (2OG) and ferrous iron dependent oxygenases are involved in many biological processes in organisms ranging from humans (where some are therapeutic targets) to plants. These enzymes are of significant biomedicinal interest because of their roles in hypoxic signaling and epigenetic regulation. Synthetic N-oxalylglycine (NOG) has been identified as a broad-spectrum 2OG oxygenase inhibitor and is currently widely used in studies on the hypoxic response and chromatin modifications in animals. We report the identification of NOG as a natural product present in Rheum rhabarbarum (rhubarb) and Spinach oleracea (spinach) leaves; NOG was not observed in Escherchia coli or human embryonic kidney cells (HEK 293T). The finding presents the possibility that NOG plays a natural role in regulating gene expression by inhibiting 2OG dependent oxygenases. This has significance because tricarboxylic acid cycle (TCA) intermediate inhibition of 2OG dependent oxygenases has attracted major interest in cancer research. PMID:26196940

  5. Effect of lead stress on mineral content and growth of wheat (Triticum aestivum) and spinach (Spinacia oleracea) seedlings

    PubMed Central

    Lamhamdi, Mostafa; El Galiou, Ouiam; Bakrim, Ahmed; Nvoa-Muoz, Juan Carlos; Arias-Estvez, Manuel; Aarab, Ahmed; Lafont, Ren

    2012-01-01

    Lead (Pb) is the most common heavy metal contaminant in the environment. Pb is not an essential element for plants, but they absorb it when it is present in their environment, especially in rural areas when the soil is polluted by automotive exhaust and in fields contaminated with fertilizers containing heavy metal impurities. To investigate lead effects on nutrient uptake and metabolism, two plant species, spinach (Spinacia oleracea) and wheat (Triticum aestivum), were grown under hydroponic conditions and stressed with lead nitrate, Pb(NO3)2, at three concentrations (1.5, 3, and 15mM). Lead is accumulated in a dose-dependent manner in both plant species, which results in reduced growth and lower uptake of all mineral ions tested. Total amounts and concentrations of most mineral ions (Na, K, Ca, P, Mg, Fe, Cu and Zn) are reduced, although Mn concentrations are increased, as its uptake is reduced less relative to the whole plants growth. The deficiency of mineral nutrients correlates in a strong decrease in the contents of chlorophylls a and b and proline in both species, but these effects are less pronounced in spinach than in wheat. By contrast, the effects of lead on soluble proteins differ between species; they are reduced in wheat at all lead concentrations, whereas they are increased in spinach, where their value peaks at 3mM Pb. The relative lead uptake by spinach and wheat, and the different susceptibility of these two species to lead treatment are discussed. PMID:23961216

  6. Interactions of plant zinc and plant species on the bioavailability of plant cadmium to Japanese quail fed lettuce and spinach

    SciTech Connect

    McKenna, I.M.; Keach, R.M. Jr; Williams, F.M. ); Chaney, R.L. Dept. of Agriculture, Beltsville, MD ); Tao, Shyy-Hwa )

    1992-02-01

    Many cadmium-contaminated environments contain high levels of zinc. The effects of plant Zn and plant species on plant Cd bioavailability were tested in Japanese quail fed lettuce and spinach. Four groups of birds received 10% of their diets as lettuce or spinach leaves intrinsically labeled with {sup 109}Cd and containing low or high intrinsic Zn. Two other groups were fed control diets containing {sup 109}Cd as CdSO{sub 4} and low or high Zn as ZnCO{sub 3}. Cadmium concentrations in diets ranged from 0.857 to 1.05 {mu}g/g dry wt. Zinc concentrations in low-Zn diets ranged from 21.2 to 22.8, and in high-Zn diets from 56.0 to 63.3 {mu}g/g dry wt. Increased lettuce and spinach Zn decreased plant Cd retention in kidney, liver, and jejunum-ileum of Japanese quail. Spinach Cd was less absorbed than lettuce Cd at both Zn levels. Inorganic Zn produced a lesser decrease in Cd retention in kidney, liver, and jejunum-ileum than did plant Zn. The authors conclude that (1) crops that transport Zn and Cd readily into edible tissues show lower Cd bioavailability when grown in Zn-Cd contaminated environments than in Cd-only polluted sites, (2) plant species differ in Cd bioavailability for identical concentrations of Zn and Cd in edible tissues, and (3) toxicological studies with animals exposed to Cd salts and Zn supplements do not assess Cd bioavailability of Zn-Cd contaminated crops.

  7. 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...

  8. Level 2 validation of a flow cytometric method for detection of Escherichia coli O157:H7 in raw spinach.

    PubMed

    Williams, Anna J; Cooper, Willie M; Summage-West, Christine V; Sims, Lillie M; Woodruff, Robert; Christman, Jessica; Moskal, Ted J; Ramsaroop, Shawn; Sutherland, John B; Alusta, Pierre; Wilkes, Jon G; Buzatu, Dan A

    2015-12-23

    The Bacteriological Analytical Manual (BAM) method currently used by the United States Food and Drug Administration (FDA) to detect Escherichia coli O157:H7 in spinach was systematically compared to a new flow cytometry based method. This Food and Drug Administration (FDA) level 2 external laboratory validation study was designed to determine the latter method's sensitivity and speed for analysis of this pathogen in raw spinach. Detection of target cell inoculations with a low cell count is critical, since enterohemorrhagic strains of E. coli require an infective dose of as few as 10 cells (Schmid-Hempel and Frank, 2007). Although, according to the FDA, the infectious dose is unknown (Food and Drug Administration, 1993). Therefore, the inoculation level into the spinach, a total of 2.0±2.6 viable E. coli O157 cells, was specified to yield between 25% and 75% detection by the new method, out of 20 samples (10 positives and 10 negatives). This criterion was met in that the new method detected 60% of the nominally positive samples; the corresponding sensitivity of the reference method was 50%. For both methods the most likely explanation for false negatives was that no viable cells were actually introduced into the sample. In this validation study, the flow cytometry method was equal to the BAM in sensitivity and far superior in speed. PMID:26318407

  9. Responses of different water spinach cultivars and their hybrid to Cd, Pb and Cd-Pb exposures.

    PubMed

    Xin, Junliang; Huang, Baifei; Yang, Zhongyi; Yuan, Jiangang; Dai, Hongwen; Qiu, Qiu

    2010-03-15

    A pot experiment was conducted to investigate the stability of Cd and/or Pb accumulation in shoot of Cd and Pb pollution-safe cultivars (PSCs), the hereditary pattern of shoot Cd accumulation, and the transfer potentials of Cd and Pb in water spinach (Ipomoea aquatica Forsk.). A typical Cd-PSC, a typical non-Cd-PSC (Cd accumulative cultivar), a hybrid from the former two cultivars, and two typical Cd+Pb-PSCs were grown in seven soils with different concentrations of Cd and Pb. The results showed that concentrations of Cd and Pb in shoot of the PSCs were always lower than the non-PSC and the highest Cd and Pb transfer factors were also always observed in the non-PSC, indicating the stability of the PSCs in Cd and Pb accumulation. Shoot Cd concentration seemed to be controlled by high Cd dominant gene(s) and thus crossbreeding might not minimize Cd accumulation in water spinach. Interaction between Cd and Pb in soils affected the accumulations of the metals in shoot of water spinach. Under middle Cd and Pb treatments, the presence of higher Pb promoted the accumulation of Cd. However, under high Pb treatment, accumulations of Cd and Pb were both restricted. PMID:19875230

  10. 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

  11. Sucrose monolaurate improves the efficacy of sodium hypochlorite against Escherichia coli O157:H7 on spinach.

    PubMed

    Xiao, Dan; Ye, Ran; Davidson, P Michael; Hayes, Douglas G; Golden, David A; Zhong, Qixin

    2011-01-31

    It is well-recognized that chlorine has limited efficacy when applied to inactivate pathogens on fresh produce. One of the many factors limiting efficacy is the high interfacial tension of chlorine-based sanitizers that limits the access of chlorine to the microorganisms. In this work, we investigated the efficacy of sodium hypochlorite (200 ppm, pH 6.0) at 4 and 20 C against Escherichia coli O157:H7 inoculated on baby spinach leaves as affected by the surfactant sucrose monolaurate (SML) at below (100 ppm), above (250 ppm), and well above (10,000 ppm) the critical micelle concentration (CMC) of ~200 ppm at 20 C. The surfactant-containing chlorine treatments were compared to those with buffer only, surfactant only, and chlorine only. Significantly improved inactivation, as evidenced by survival of E. coli O157:H7 was achieved when 250 or 10,000 ppm SML was added with chlorine. This is attributed to the reduction of interfacial tension between the sanitizing solutions and spinach surface. Treatments at 20 C resulted in greater mean inactivation than those at 4 C but the difference was not significant. Comparisons of SML concentrations in treatment solutions before and after sanitization showed that SML decreased more at a lower temperature and when chlorine was present, resulting from adsorption of SML onto spinach matrix. Our work illustrates the importance of using surfactants at concentrations above the CMC to enhance the efficacy of chlorine sanitization. PMID:21168229

  12. 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

  13. 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.).

  14. 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 μmol 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

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

    PubMed

    Williams, John F; MacLeod, John K

    2006-11-01

    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 CO(2) 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 micromol 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

  16. Exserohilum Leaf Spot on Tigergrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  17. How to pattern a leaf

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  18. Isolation and characterization of structurally novel antimutagenic flavonoids from spinach (Spinacia oleracea).

    PubMed

    Edenharder, R; Keller, G; Platt, K L; Unger, K K

    2001-06-01

    Thirteen compounds, isolated from spinach (Spinacia oleracea), acted as antimutagens against the dietary carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline in Salmonella typhimurium TA 98. The antimutagens were purified by preparative and micropreparative HPLC from a methanol/water (70:30, v/v) extract of dry spinach (commercial product) after removal of lipophilic compounds such as chlorophylls and carotenoids by solid-phase extraction (SPE). Pure active compounds were identified by instrumental analysis including FT-IR, (1)H and (13)C NMR, UV-vis spectroscopy, and mass spectrometry. All of these compounds were flavonoids and related compounds that could be attributed to five groups: (A, methylenedioxyflavonol glucuronides) 5,3'-dihydroxy-4'-methoxy-6,7-methylenedioxyflavonol 3-O-beta-glucuronide (compound 1), 5,2',3'-trihydroxy-4'-methoxy-6,7-methylenedioxyflavonol 3-O-beta-glucuronide (compound 2), 5-hydroxy-3',4'-dimethoxy-6,7-methylenedioxyflavonol 3-O-beta-glucuronide (compound 3); (B, flavonol glucuronides) 5,6,3'-trihydroxy-7,4'-dimethoxyflavonol 3-O-beta-glucuronide (compound 4), 5,6-dihydroxy-7,3',4'-trimethoxyflavonol 3-O-beta-glucuronide (compound 5); (C, flavonol disaccharides) 5,6,4'-trihydroxy-7,3'-dimethoxyflavonol 3-O-disaccharide (compound 6), 5,6,3',4'-tetrahydroxy-7-methoxyflavonol 3-O-disaccharide (compounds 7 and 8); (D, flavanones) 5,8,4'-trihydroxyflavanone (compound 9), 7,8,4'-trihydroxyflavanone (compound 10); (E, flavonoid-related compounds) compounds 11, 12, and 13 with incompletely elucidated structures. The yield of compound 1 was 0.3%, related to dry weight, whereas the yields of compounds 2-13 ranged between 0.017 and 0.069%. IC(50) values (antimutagenic potencies) of the flavonol glucuronides ranged between 24.2 and 58.2 microM, whereas the flavonol disaccharides (compounds 7 and 8), the flavanones (compounds 9 and 10), and the flavonoid-related glycosidic compounds 11-13 were only weakly active. The aglycons of compounds 7 and 8, however, were potent antimutagens (IC(50) = 10.4 and 13.0 microM, respectively). PMID:11409964

  19. Three-dimensional solution structure and stability of thioredoxin m from spinach.

    PubMed

    Neira, J L; Gonzlez, C; Toiron, C; de Prat-Gay, G; Rico, M

    2001-12-18

    Proton NMR spectral resonances of thioredoxin m from spinach have been assigned, and its solution structure has been determined on the basis of 1156 nuclear Overhauser effect- (NOE-) derived distance constraints by using restrained molecular dynamics calculations. The average pairwise root-mean-square deviation (RMSD) for the 25 best NMR structures for the backbone was 1.0 +/- 0.1, when the structurally well-defined residues were considered. The N- and C-terminal segments (1-13 and 118-119) and residues 41-49, comprising the active site, are highly disordered. At the time of concluding this work, a crystal structure of this protein was reported, in which thioredoxin m was found to crystallize as noncovalent dimers. Although the solution and crystal structures are very similar, no evidence was found about the existence of dimers in solution, thus confirming that dimerization is not needed for the regulatory activity of thioredoxin m. The spinach thioredoxin m does not unfold by heat in the range 25-85 degrees C, as revealed by thermal circular dichroic (CD) measurements. However, its unfolding free energy (9.1 +/- 0.8 kcal mol(-1), at pH 5.3 and 25 degrees C) could be determined by extrapolating the free energy values obtained at different concentrations of guanidinium chloride (GdmCl). The folding-unfolding process is two-state as indicated by the coincidence of the CD denaturation curves obtained at far and near UV. The H/D exchange behavior of backbone amide protons was analyzed. The slowest-exchanging protons, requiring a global-unfolding mechanism in order to exchange, are those from beta2, beta3, and beta4, the central strands of the beta-sheet, which constitute the main element of the core of the protein. The free energies obtained from exchange measurements of protons belonging to the alpha-helices are lower than those derived from GdmCl denaturation studies, indicating that those protons exchange by local-unfolding mechanisms. PMID:11735407

  20. Biologically active fluorescent derivatives of spinach calmodulin that report calmodulin target protein binding.

    PubMed

    Mills, J S; Walsh, M P; Nemcek, K; Johnson, J D

    1988-02-01

    Spinach calmodulin (CaM) has been labeled at cysteine-26 with the sulfhydryl-selective probe 2-(4-maleimidoanilino)naphthalene-6-sulfonic acid (MIANS) to produce MIANS-CaM. The interaction of MIANS-CaM with CaM binding proteins was studied by fluorescence enhancement accompanying the protein-protein interactions. MIANS-CaM bound to smooth muscle myosin light-chain kinase with a Kd of 9 nM, causing a 4.6-fold fluorescence enhancement. Caldesmon bound with a Kd of 250 nM, causing a 2-fold fluorescence enhancement. Calcineurin (CaN) bound to MIANS-CaM with a Kd less than 5 nM, causing an 80% increase in fluorescence. On the other hand, binding of the CaM antagonist drugs prenylamine and calmidazolium or the potent peptide antagonist melittin did not alter MIANS fluorescence. MIANS-CaM activated brain cGMP phosphodiesterase and CaN as effectively as unlabeled CaM. Spinach CaM was also labeled with three other sulfhydryl reagents, 6-acryloyl-2-(dimethylamino)naphthalene, (2,5-dimethoxy-4-stilbenyl)maleimide, and rhodamine X maleimide. CaN bound to the highly fluorescent rhodamine X maleimidyl-CaM with a Kd of 1.4 nM, causing a 25% increase in polarization. Both MIANS-CaM and rhodamine X-CaM were used to monitor the Ca2+ dependence of the interaction between CaM and CaN. Half-maximal binding occurred at pCa 6.7-6.8 in the absence of Mg2+, or at pCa 6.3 in the presence of 3 mM Mg2+. In both cases, the dependence of the interaction was cooperative with respect to Ca2+ (Hill coefficients of 1.7-2.0). Use of these fluorescent CaMs should allow accurate monitoring of CaM interactions with its target proteins and perhaps their localization within the cell. PMID:3365375

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

    PubMed Central

    Balakrishna, AshaManikkoth; Seelert, Holger; Marx, Sven-Hendric; Dencher, NorbertA.; Grber, 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 , and ?=104.34 and diffracted to 4.5 resolution. Each c-ring contains 14 monomers in the asymmetric unit. The length of the c-ring is 60.32 , with an outer ring diameter 52.30 and an inner ring width of 40 . PMID:24521269

  2. CARBONIC ANHYDRASE ACTIVITY OF INTEGRAL-FUNCTIONAL COMPLEXES OF THYLAKOID MEMBRANES OF SPINACH CHLOROPLASTS.

    PubMed

    Semenihin, A V; Zolotareva, O K

    2015-01-01

    Isolated thylakoid membranes were disrupted by treatment with nonionic detergents digitonin or dodecyl maltoside. Solubilized polypeptide complexes were separated by native gel charge shift electrophoresis. The position of ATP-synthase complex and its isolated catalytic part (CF1) within gel was determined using the color reaction for ATPase activity. Due to the presence of cytochromes, the red band in unstained gels corresponded to the cytochrome b6f complex. Localization of the cytochrome b6f complex, ATP synthase and coupling CF1 in the native gel was confirmed by their subunit composition determined after SDS-electrophoretic analysis. Carbonic anhydrase (CA) activity in polypeptide zones of PS II, cytochrome b6f complex, and ATP-synthase CF1 was identified in native gels using indicator bromothymol blue. CA activity of isolated CF1 in solution was determined by infrared gas analysis as the rate of bicarbonate dehydration. The water-soluble acetazolamide, an inhibitor of CA, unlike lipophilic ethoxyzolamide inhibited CA activity of CF1 Thus, it was shown for the first time that ATP-synthase has a component which is capable of catalyzing the interconversion of forms of carbonic acid associated with proton exchange. The data obtained suggest the presence of multiple forms of carbonic anhydrase in the thylakoid membranes of spinach chloroplasts and confirm their involvement in the proton transfer to the ATP synthase. PMID:26502699

  3. Evidence for a reactive cysteine at the nucleotide binding site of spinach ribulose-5-phosphate kinase

    SciTech Connect

    Omnaas, J.; Porter, M.A.; Hartman, F.C.

    1985-02-01

    Ribulose-5-phosphate kinase from spinach was rapidly inactivated by N-bromoacetylethanolamine phosphate in a bimolecular fashion with a k2 of 2.0 m s at 2C and pH 8.0. Ribulose 5-phosphate had little effect on the rate of inactivation, whereas complete protection was afforded by ADP or ATP. The extent of incorporation as determined with UC-labeled reagent was about 1 molar equivalent per subunit in the presence of ATP with full retention of enzymatic activity, and about 2 molar equivalents per subunit in the completely inactivated enzyme. Amino acid analyses of enzyme derivatized with UC-labeled reagent reveal that all of the covalently incorporated reagent was associated with cysteinyl residues. Hence, two sulfhydryls are reactive, but the inactivation correlates with alkylation of one cysteinyl residue at or near the enzyme's nucleotide binding site. The kinase was also extremely sensitive to the sulfhydryl reagents 5,5'-dithiobis(2-nitrobenzoic acid) and N-ethylmaleimide. The reactive sulfhydryl groups are likely to be those generated by reduction of a disulfide during activation. 20 references, 3 figures, 2 tables.

  4. 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.

  5. Effects of inorganic phosphate on the light dependent thylakoid energization of intact spinach chloroplasts

    SciTech Connect

    Heineke, D.; Heldt, H.W. ); Stitt, M. )

    1989-09-01

    The light dependent energization of the thylakoid membrane was analyzed in isolated intact spinach (Spinacia oleracea L.) chloroplasts incubated with different concentrations of inorganic phosphate (Pi). Two independent methods were used: (a) the accumulation of ({sup 14}C)5,5-dimethyl-2,4-oxazolidinedione and ({sup 14}C)methylamine; (b) the energy dependent chlorophyll fluorescence quenching. The inhibition of CO{sub 2} fixation by superoptimal medium Pi or by adding glyceraldehyde - an inhibitor of the Calvin cycle - leads to an increased energization of the thylakoid membrane; however, the membrane energization decreases when chloroplasts are inhibited by suboptimal Pi. This specific low phosphate effect could be partially reversed by adding oxaloacetate, which regenerates the electron acceptor NADP{sup +} and stimulates linear electron transport. The energization seen in low Pi is, however, always lower than in superoptimal Pi, even in the presence of oxaloacetate. Energization recovers in the presence of low amounts of N,N{prime}-dicyclohexylcarbodiimide, which reacts with proton channels including the coupling factor 1 ATP synthase. N,N{prime}-Dicyclohexylcarbodiimide has no effect on energization of chloroplasts in superoptimal Pi. These results suggest there is a specific low phosphate proton leak in the thylakoids, and its origin is discussed.

  6. Survival of Salmonella enterica in Dried Turkey Manure and Persistence on Spinach Leaves.

    PubMed

    Oni, Ruth A; Sharma, Manan; Buchanan, Robert L

    2015-10-01

    Concerns about the microbiological safety of fresh produce have attracted attention in the past three decades due to multiple foodborne outbreaks. Animal manure contaminated with enteric pathogens has been identified as an important preharvest pathogen source. This study investigated the survival of Salmonella enterica in dust particles of dehydrated turkey manure and how association with manure dust may enhance the survival of salmonellae on leafy greens in the field. The survival of a cocktail of multiple Salmonella serotypes in the dried fecal material of various particle sizes (125 to 500 μm) was examined at varying moisture contents (5, 10, and 15%). Survival times of the pathogen were inversely related to moisture content and particle size of manure dust, with viable Salmonella still detectable for up to 291 days in the smallest particle size (125 μm) with 5% moisture. Association with manure dust particles increased the survival of Salmonella when subjected to UV light both under laboratory conditions and on the surface of spinach leaves in a greenhouse setting. The results of this study suggest that aerosolized manure particles could be a potential vehicle for Salmonella dispersal to leafy greens if the microorganism is present in the dry manure. PMID:26408127

  7. 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 μm biomimetic dimyristoylphosphatidylcholine (DMPC) film on a pyrolytic graphite (PG) anode with PSII embedded in multiple lipid bilayers. The photocurrent was ∼20 μA 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 μW 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

  8. Organellar and Cytosolic Localization of Four Phosphoribosyl Diphosphate Synthase Isozymes in Spinach

    PubMed Central

    Krath, Britta N.; Hove-Jensen, Bjarne

    1999-01-01

    Four cDNAs encoding phosphoribosyl diphosphate (PRPP) synthase were isolated from a spinach (Spinacia oleracea) cDNA library by complementation of an Escherichia coli Δprs mutation. The four gene products produced PRPP in vitro from ATP and ribose-5-phosphate. Two of the enzymes (isozymes 1 and 2) required inorganic phosphate for activity, whereas the others were phosphate independent. PRPP synthase isozymes 2 and 3 contained 76 and 87 amino acid extensions, respectively, at their N-terminal ends in comparison with other PRPP synthases. Isozyme 2 was synthesized in vitro and shown to be imported and processed by pea (Pisum sativum) chloroplasts. Amino acid sequence analysis indicated that isozyme 3 may be transported to mitochondria and that isozyme 4 may be located in the cytosol. The deduced amino acid sequences of isozymes 1 and 2 and isozymes 3 and 4 were 88% and 75% identical, respectively. In contrast, the amino acid identities of PRPP synthase isozyme 1 or 2 with 3 or 4 was modest (22%–25%), but the sequence motifs for binding of PRPP and divalent cation-nucleotide were identified in all four sequences. The results indicate that PRPP synthase isozymes 3 and 4 belong to a new class of PRPP synthases that may be specific to plants. PMID:9952445

  9. Partial purification of gibberellin oxidases from spinach leaves. [Spinacia oleracea L

    SciTech Connect

    Gilmour, S.J.; Bleecker, A.B.; Zeevaart, J.A.D.

    1987-09-01

    Four enzyme activities catalyzing the following oxidative steps in the gibberellin (GA) biosynthetic pathway have been extracted from spinach (Spinacia oleracea L.) leaves after exposure to 8 long days: GA/sub 12/ ..-->.. GA/sub 53/ ..-->.. GA/sub 44/ ..-->.. GA/sub 19/ ..-->.. GA/sub 20/. Two of these, GA/sub 53/ oxidase and GA/sup 19/ oxidase, were separable from the other two, GA/sub 44/ oxidase and GA/sub 12/ 13-hydroxylase, by anion exchange high performance liquid chromatography (HPLC). Apparent molecular weights of the four enzymes as determined by gel filtration HLPL are: GA/sub 12/ 13-hydroxylase, 28,400; GA/sub 43/ oxidase, 42,500; GA/sub 44/ oxidase, 38,100; GA/sub 19/ oxidase, 39,500. GA/sub 44/ oxidase was purified approximately 100-fold in 0.3% yield by a combination of ammonium sulfate fractionation, anion exchange HPLC, phenyl-Sepharose chromatography and gel filtration HLPC.

  10. beta. -carotene synthesis in spinach chloroplasts is tightly linked to photosynthetic carbon metabolism

    SciTech Connect

    Schulze-Siebert, D.; Schultz, G.

    1987-04-01

    When purified, highly intact spinach chloroplasts were illuminated in the presence of NaH/sup 14/CO/sub 3/, the largest portion of acetate derived compounds formed was ..beta..-carotene and not fatty acids (20 and 2.5 natoms C incorporated/mg chlorophyll x h when 5 mM NaH /sup 14/CO/sub 3/ was used). From isotopic dilution experiments applying glyceraldehyde 3-P, dihydroxyacetone-P, 3-phosphoglycerate (3-PGA), 2-PGA, phosphoenolpyruvate (PEP) and pyruvate, respectively, evidence was obtained that acetyl-CoA to form isopentenyl-PP (IPP) originates from a low capacity but highly effective flow from photosynthetic CO/sub 2/-fixation via 3-PGA - 2-PGA - PEP - pyruvate. Phosphoglycerate mutase in chloroplasts, of which the presence hitherto was not unequivocally proven, was detected by (i) latency technique and (ii) feeding/1-/sup 14/C/glycerate and following 3-PGA, 2-PGA, PEP and pyruvate level in chloroplasts and suspension medium. From highly effective synthesis of ..beta..-carotene from CO/sub 2/ conclusion may be drawn that pathways for both, acetyl compounds and IPP, to form isoprenoids must exist in chloroplasts.

  11. Defining the far-red limit of photosystem II in spinach.

    PubMed

    Thapper, Anders; Mamedov, Fikret; Mokvist, Fredrik; Hammarstrm, Leif; Styring, Stenbjrn

    2009-08-01

    The far-red limit of photosystem II (PSII) photochemistry was studied in PSII-enriched membranes and PSII core preparations from spinach (Spinacia oleracea) after application of laser flashes between 730 and 820 nm. Light up to 800 nm was found to drive PSII activity in both acceptor side reduction and oxidation of the water-oxidizing CaMn(4) cluster. Far-red illumination induced enhancement of, and slowed down decay kinetics of, variable fluorescence. Both effects reflect reduction of the acceptor side of PSII. The effects on the donor side of PSII were monitored using electron paramagnetic resonance spectroscopy. Signals from the S(2)-, S(3)-, and S(0)-states could be detected after one, two, and three far-red flashes, respectively, indicating that PSII underwent conventional S-state transitions. Full PSII turnover was demonstrated by far-red flash-induced oxygen release, with oxygen appearing on the third flash. In addition, both the pheophytin anion and the Tyr Z radical were formed by far-red flashes. The efficiency of this far-red photochemistry in PSII decreases with increasing wavelength. The upper limit for detectable photochemistry in PSII on a single flash was determined to be 780 nm. In photoaccumulation experiments, photochemistry was detectable up to 800 nm. Implications for the energetics and energy levels of the charge separated states in PSII are discussed in light of the presented results. PMID:19700631

  12. 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

  13. Isolation and Quantitation of β-d-Glucopyranosyl Abscisate from Leaves of Xanthium and Spinach 12

    PubMed Central

    Boyer, Gregory L.; Zeevaart, Jan A. D.

    1982-01-01

    From previous work (Zeevaart 1980 Plant Physiol 66: 672-678) 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, β-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 abscisic 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 β-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. β-d-glycopyranosyl abscisate in Xanthium leaves may be a stable end product of abscisic acid metabolism. PMID:16662451

  14. Carbon dioxide assimilation by leaves, isolated chloroplasts, and ribulose bisphosphate carboxylase from spinach.

    PubMed

    Lilley, R M; Walker, D A

    1975-06-01

    The relationship between rate of photosynthesis and CO(2) concentration has been reinvestigated using isolated spinach (Spinacia oleracea) chloroplasts. The apparently low CO(2) concentration required for half-maximal photosynthesis is shown to result partly from a ceiling imposed by electron transport. In double reciprocal plots of rate against CO(2) concentration, this ceiling results in departures from linearity at high CO(2) concentrations. If these rate limitations are disregarded in extrapolation the "true" CO(2) concentration required for half maximal carboxylation by intact chloroplasts is approximately 46 mum (CO(2)).When assayed under comparable conditions, ribulose bisphosphate carboxylase from these chloroplasts also shows an apparent Km (CO(2)) of approximately 46 mum, suggesting that its characteristics are not modified by extraction. An improved assay for ribulose bisphosphate carboxylase yielded rates of carboxylation considerably higher than those previously reported, the highest maximal velocities recorded approaching 1000 mumoles CO(2) fixed mg(-1) chlorophyll hr(-1) at 20 C. With such Km and V(max), values the carboxylase would be able to achieve, at concentrations of CO(2) less than atmospheric, rates of CO(2) fixation equal to those displayed by the parent tissue or by the average plant under favorable conditions in its natural environment. PMID:16659216

  15. Toxicity and Bioaccumulation of Heavy Metals in Spinach (Spinacia oleracea) Grown in a Controlled Environment

    PubMed Central

    Alia, Naz; Sardar, Khan; Said, Muhammad; Salma, Khalid; Sadia, Alam; Sadaf, Siddique; Toqeer, Ahmed; Miklas, Scholz

    2015-01-01

    The impact of heavy metal toxicity on the shoot and root lengths, total protein, fiber characteristics, moisture content and nutrient composition of spinach (Spinacia oleracea) was evaluated. Plants were grown in pots containing soil and treated with different concentrations (mg/kg) of lead (Pb; 300, 400 and 500), cadmium (Cd; 0.5, 1 and 1.5) and zinc (Zn; 250, 500, and 700) as well as mixtures of Cd and Pb (0.5/300, 1/400, 1.5/500), Cd and Zn (0.5/250, 1/500, 1.5/700), and Pb and Zn (300/250, 400/500, 500/700). Soil contaminated by long-term irrigation with wastewater containing heavy metals was simulated. An increase in concentrations of heavy metals both individually and as mixtures significantly (p < 0.05) reduced the growth parameters and nutrient contents of S. oleracea. The uptake patterns of heavy metals in mixtures showed antagonistic impacts on each other. The toxicities of the mixtures Cd and Pb, Cd and Zn as well as Pb and Zn were higher than those observed in separate heavy metal applications but less than their additive sums. The toxicity caused by individual heavy metals was the highest for Cd followed by Pb and Zn. The highest toxicity was observed in plants grown in soil contaminated by Cd and Pb. PMID:26133131

  16. Effects of ultrasonic treatments on the polyphenol and antioxidant content of spinach extracts.

    PubMed

    Altemimi, Ammar; Choudhary, Ruplal; Watson, Dennis G; Lightfoot, David A

    2015-05-01

    The objective was to test ultrasound treatments on spinach leaves during extraction, and conventional extraction was used as a control. The effects of different combinations of the ultrasonic water bath factors tested on phenolic compound yields included frequency (37 and 80 kHz), exposure time (5, 10, 15, 20, 25, and 30 min), temperature (30, 40, and 50°C), and ultrasonic power (30%, 50%, and 70%). The best conditions for extraction yields were ultrasonic frequency of 37 kHz, extraction time of 30 min, reaction temperature of 40°C, and ultrasonic power of 50%. The mean yield (mg/100g), total phenol (mg gallic acid/g DW), flavonoids (mg/g DW), % DPPH free-radical scavenging activity, and % ferric reducing antioxidant power were all high (64.88 ± 21.84, 33.96 ± 11.30, 27.37 ± 11.85, 64.18 ± 16.69 and 70.25 ± 9.68). Treatments were significantly different. The interaction among the ultrasonic parameters was significant. Temperature and power had significant effects on all other dependent variables. PMID:25465093

  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. Nanodomains of cytochrome b6f and photosystem II complexes in spinach grana thylakoid membranes.

    PubMed

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

    2014-07-01

    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

  19. Toxicity and Bioaccumulation of Heavy Metals in Spinach (Spinacia oleracea) Grown in a Controlled Environment.

    PubMed

    Alia, Naz; Sardar, Khan; Said, Muhammad; Salma, Khalid; Sadia, Alam; Sadaf, Siddique; Toqeer, Ahmed; Miklas, Scholz

    2015-07-01

    The impact of heavy metal toxicity on the shoot and root lengths, total protein, fiber characteristics, moisture content and nutrient composition of spinach (Spinacia oleracea) was evaluated. Plants were grown in pots containing soil and treated with different concentrations (mg/kg) of lead (Pb; 300, 400 and 500), cadmium (Cd; 0.5, 1 and 1.5) and zinc (Zn; 250, 500, and 700) as well as mixtures of Cd and Pb (0.5/300, 1/400, 1.5/500), Cd and Zn (0.5/250, 1/500, 1.5/700), and Pb and Zn (300/250, 400/500, 500/700). Soil contaminated by long-term irrigation with wastewater containing heavy metals was simulated. An increase in concentrations of heavy metals both individually and as mixtures significantly (p < 0.05) reduced the growth parameters and nutrient contents of S. oleracea. The uptake patterns of heavy metals in mixtures showed antagonistic impacts on each other. The toxicities of the mixtures Cd and Pb, Cd and Zn as well as Pb and Zn were higher than those observed in separate heavy metal applications but less than their additive sums. The toxicity caused by individual heavy metals was the highest for Cd followed by Pb and Zn. The highest toxicity was observed in plants grown in soil contaminated by Cd and Pb. PMID:26133131

  20. Nodularin uptake and induction of oxidative stress in spinach (Spinachia oleracea).

    PubMed

    Lehtimäki, Nina; Shunmugam, Sumathy; Jokela, Jouni; Wahlsten, Matti; Carmel, Dalton; Keränen, Mika; Sivonen, Kaarina; Aro, Eva-Mari; Allahverdiyeva, Yagut; Mulo, Paula

    2011-04-15

    The bloom-forming cyanobacterium Nodularia spumigena produces toxic compounds, including nodularin, which is known to have adverse effects on various organisms. We monitored the primary effects of nodularin exposure on physiological parameters in Spinachia oleracea. We present the first evidence for the uptake of nodularin by a terrestrial plant, and show that the exposure of spinach to cyanobacterial crude water extract from nodularin-producing strain AV1 results in inhibition of growth and bleaching of the leaves. Despite drastic effects on phenotype and survival, nodularin did not disturb the photosynthetic performance of plants or the structure of the photosynthetic machinery in the chloroplast thylakoid membrane. Nevertheless, the nodularin-exposed plants suffered from oxidative stress, as evidenced by a high level of oxidative modifications targeted to various proteins, altered levels of enzymes involved in scavenging of reactive oxygen species (ROS), and increased levels of α-tocopherol, which is an important antioxidant. Moreover, the high level of cytochrome oxidase (COX II), a typical marker for mitochondrial respiratory protein complexes, suggests that the respiratory capacity is increased in the leaves of nodularin-exposed plants. Actively respiring plant mitochondria, in turn, may produce ROS at high rates. Although the accumulation of ROS and induction of the ROS scavenging network enable the survival of the plant upon toxin exposure, the upregulation of the enzymatic defense system is likely to increase energetic costs, reducing growth and the ultimate fitness of the plants. PMID:21093957

  1. Preparation and multiple antitumor properties of AuNRs/spinach extract/PEGDA composite hydrogel.

    PubMed

    Wang, Yunlong; Zhang, Buchang; Zhu, Lin; Li, Yanjie; Huang, Fangzhi; Li, Shikuo; Shen, Yuhua; Xie, Anjian

    2014-09-10

    In this study, a novel composite hydrogel that contains spinach extract (SE), gold nanorods (AuNRs), and poly(ethylene glycol) double acrylates (PEGDA) is prepared through a one-step in situ photopolymerization under noninvasive 660 nm laser irradiation for localized antitumor activity. SE plays a role as a photoinitiator for initiating the formation of the PEGDA hydrogel and as an excellent photosensitizer for generating cytotoxic singlet oxygen ((1)O2) with oxygen to kill tumor cells. AuNRs can be used as a photoabsorbing agent to generate heat from optical energy. Moreover, the introduction of AuNRs is conducive to the formation of the hydrogel and accelerates the rate of (1)O2 generation. The composite hydrogel shell, which has good biocompatibility on tumor cells, can prevent the photosensitizer from migrating to normal tissue and maintains a high concentration on lesions, thereby enhancing the curative effect. The combination of NIR light-triggered mild photothermal heating of AuNRs, the photodynamic treatment using SE, and localized gelation by photopolymerization exhibits a synergistic effect for the destruction of cancer cells. PMID:25111567

  2. Spectral characterization in a supersonic beam of neutral chlorophyll a evaporated from spinach leaves

    NASA Astrophysics Data System (ADS)

    Shafizadeh, N.; Ha-Thi, M. H.; Soep, B.; Gaveau, M. A.; Piuzzi, F.; Pothier, C.

    2011-09-01

    The observation of the light absorption of neutral biomolecules has been made possible by a method implemented for their preparation in the gas phase, in supersonically cooled molecular beams, based upon the work of Focsa et al. [C. Mihesan, M. Ziskind, B. Chazallon, E. Therssen, P. Desgroux, S. Gurlui, and C. Focsa, Appl. Surf. Sci. 253, 1090 (2006)], 10.1016/j.apsusc.2006.01.082. The biomolecules diluted in frozen water solutions are entrained in the gas plume of evaporated ice generated by an infrared optical parametric oscillators (OPO) laser tuned close to its maximum of absorption, at ˜3 μm. The biomolecules are then picked up in the flux of a supersonic expansion of argon. The method was tested with indole dissolved in water. The excitation spectrum of indole was found cold and large clusters of indole with water were observed up to n = 75. Frozen spinach leaves were examined with the same method to observe the chlorophyll pigments. The Qy band of chlorophyll a has been observed in a pump probe experiment. The Qy bands of chlorophyll a is centred at 647 nm, shifted by 18 nm from its position in toluene solutions. The ionization threshold could also be determined as 6.1 ± 0.05 eV.

  3. Effects of temperature pretreatment in the dark on photosynthesis of the intact spinach chloroplast.

    PubMed

    Fu, C F; Gibbs, M

    1988-09-01

    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 degrees C. Dark incubation of the chloroplasts for 10 minutes at 35 degrees C and pH 8.1 resulted in a 50% decline in CO(2) 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 degrees 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 degrees 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

  4. On the role of the acidic cluster Glu 92-94 of spinach ferredoxin I.

    PubMed

    Aliverti, A; Livraghi, A; Piubelli, L; Zanetti, G

    1997-09-26

    The role of the acidic cluster Glu 92-94 of spinach ferredoxin I in the interaction both with the photosystem I multisubunit complex and the ferredoxin-NADP+ reductase, either membrane-bound or purified, was studied by kinetic characterization of site-directed mutants. Three mutants of ferredoxin have been produced to evaluate the effects of elimination of one or two negative charges in the three specific positions of the acidic cluster. Kinetic characterization of the ferredoxin mutants E92A/E93A, E93A and E93A/E94A as electron carriers in the photosynthetic electron transport chain, allowed to establish that the two latter mutants were nearly indistinguishable from the wild-type protein in their ability to be photoreduced by photosystem I and as electron donor to the reductase in the NADP+ photoreduction with thylakoid membranes. The E92A/E93A ferredoxin mutant behaved very similarly to E92 mutants previously characterized. Thus, the elimination of the carboxyl groups adjacent to residue 92 did not further impaired ferredoxin I main function, i.e., as an electron carrier in NADP+ photoreduction. The two double mutants showed a reduced rate in the cross-linking of ferredoxin to the reductase promoted by a soluble carbodiimide, indicating an involvement of the acidic cluster in the formation of the active covalent complex between the two proteins. PMID:9366269

  5. Effects of Inorganic Phosphate on the Light Dependent Thylakoid Energization of Intact Spinach Chloroplasts 1

    PubMed Central

    Heineke, Dieter; Stitt, Mark; Heldt, Hans W.

    1989-01-01

    The light dependent energization of the thylakoid membrane was analyzed in isolated intact spinach (Spinacia oleracea L.) chloroplasts incubated with different concentrations of inorganic phosphate (Pi). Two independent methods were used: (a) the accumulation of [14C]5,5-dimethyl-2,4-oxazolidinedione and [14C] methylamine; (b) the energy dependent chlorophyll fluorescence quenching. The inhibition of CO2 fixation by superoptimal medium Pi or by adding glyceraldehydean inhibitor of the Calvin cycleleads to an increased energization of the thylakoid membrane; however, the membrane energization decreases when chloroplasts are inhibited by suboptimal Pi. This specific `low phosphate' effect could be partially reversed by adding oxaloacetate, which regenerates the electron acceptor NADP+ and stimulates linear electron transport. The energization seen in low Pi is, however, always lower than in superoptimal Pi, even in the presence of oxaloacetate. Energization recovers in the presence of low amounts of N,N?-dicyclohexylcarbodiimide, which reacts with proton channels including the coupling factor 1 ATP synthase. N,N?-Dicyclohexylcarbodiimide has no effect on energization of chloroplasts in superoptimal Pi. These results suggest there is a specific `low phosphate' proton leak in the thylakoids, and its origin is discussed. PMID:16667000

  6. X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

    SciTech Connect

    Andrews, J.C.

    1995-08-01

    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. Attention is focused on the following: photosynthesis and the oxygen evolving complex; determination of mosaic spread in oriented photosystem II particles from signal II EPR measurement; oriented EXAFS--studies of PS II in the S{sub 2} state; structural changes in PS II as a result of treatment with ammonia: EPR and XAS studies; studies of halide binding to Mn: Cl K-edge and Mn EXAFS of Mn-Cl model compounds and Mn EXAFS of oriented Br-treated photosystem II.

  7. Direct desaturation of intact galactolipids by a desaturase solubilized from spinach (Spinacia oleracea) chloroplast envelopes.

    PubMed Central

    Schmidt, H; Heinz, E

    1993-01-01

    In plants, polyenoic fatty acids are synthesized by desaturase enzymes which use acyl groups of membrane lipids as substrates. To provide direct 'in vitro' evidence for this reaction, we solubilized envelope membranes from spinach (Spinacia oleracea) chloroplasts with Triton X-100 to release a membrane-bound n-6 desaturase. In the presence of oxygen and reduced ferredoxin, the solubilized enzyme desaturated a variety of substrates, such as free oleic acid, free erucic acid, 1-oleoyl-sn-glycerol 3-phosphate and the three galactolipids 1-oleoyl-2-(7'-cis-hexadecenoyl)-3-beta-D-galactopyranosyl-sn-glycerol, 1,2-dioleoyl-3-beta-D-galactopyranosyl-sn-glycerol and the ether analogue 1,2-di-(9'-cis-octadecenyl)-3-beta-D-galactopyranosyl-sn- glycerol. The in vitro desaturation of these exogenously added complex lipids with ester- and ether-linked substrate chains is unambiguous evidence for lipid-linked desaturation. The enzyme measures the insertion of the new double bond from the methyl end and the existing (n-9)-cis-double bond of an appropriate acyl or alkyl chain. The distal part of the substrate group, normally the carboxy end of a fatty acyl residue, is of less importance and, in particular, its activation in thioester form is not required. PMID:8435075

  8. Peanut leaf inspired multifunctional surfaces.

    PubMed

    Yang, Shuai; Ju, Jie; Qiu, Yuchen; He, Yaxu; Wang, Xiaolin; Dou, Shixue; Liu, Kesong; Jiang, Lei

    2014-01-29

    Nature has long served as a source of inspiration for scientists and engineers to design and construct multifunctional artificial materials. The lotus and the peanut are two typical plants living in the aquatic and the arid (or semiarid) habitats, respectively, which have evolved different optimized solutions to survive. For the lotus leaf, an air layer is formed between its surface and water, exhibiting a discontinuous three-phase contact line, which resulted in the low adhesive superhydrophobic self-cleaning effect to avoid the leaf decomposition. In contrast to the lotus leaf, the peanut leaf shows high-adhesive superhydrophobicity, arising from the formation of the quasi-continuous and discontinuous three-phase contact line at the microscale and nanoscale, respectively, which provides a new avenue for the fabrication of high adhesive superhydrophobic materials. Further, this high adhesive and superhydrophobic peanut leaf is proved to be efficient in fog capture. Inspired by the peanut leaf, multifunctional surfaces with structural similarity to the natural peanut leaf are prepared, exhibiting simultaneous superhydrophobicity and high adhesion towards water. PMID:23908145

  9. Investigation of the extraction behavior of the main monoglutamate folates from spinach by liquid chromatography-electrospray ionization tandem mass spectrometry.

    PubMed

    Zhang, Guo-Fang; Storozhenko, Sergei; Van Der Straeten, Dominique; Lambert, Willy E

    2005-06-17

    An LC-MS/MS method has been developed for the determination of main monoglutamate folates in spinach with folic acid as an internal standard. A sample preparation with ultrafiltration (molecular weight cut-off membrane, 5 kDa) was followed by a chromatographic run of 14.2 min, rendering the method very simple and fast. The LODs in diluted spinach matrix were 0.02, 0.09, 0.05 and 0.03 ng/mL (0.037, 0.17, 0.092 and 0.055 microg/100 g calculated according to the fresh weight of spinach) for 5-methyltetrahydrofolate, tetrahydrofolate, 5-formyltetrahydrofolate, and 10-formylfolic acid, respectively. Using this method, the extraction behaviour of the main naturally occurring monoglutamate folates has been investigated in detail. It is found that 10 min of heating at 100 degrees C, incubation with rat serum at 37 degrees C (0.05 M phosphate buffer, pH = 6.5) for 4 h and the ratio of 10 (volume of extraction buffer versus the weight of sample, mL/g) are the optimal parameters for folate extraction from spinach. The final quantitative result of the individual folates in spinach is highly influenced by the pH (from 2.9 to 8.6) of the extraction buffer. PMID:16007982

  10. Heterologous C-terminal signals effectively target fluorescent fusion proteins to leaf peroxisomes in diverse plant species.

    PubMed

    Gnanasambandam, Annathurai; Anderson, David J; Mills, Edwina; Brumbley, Stevens M

    2012-05-15

    Peroxisomes are functionally diverse organelles that are wholly dependent on import of nuclear-encoded proteins. The signals that direct proteins into these organelles are either found at the C-terminus (type 1 peroxisomal targeting signal; PTS1) or N-terminus (type 2 peroxisomal targeting signal; PTS2) of the protein. Based on a limited number of tests in heterologous systems, PTS1 signals appear to be conserved across species. To further test the generality of this conclusion and to establish the extent to which the PTS1 signals can be relied on for biotechnological purposes across species, we tested two PTS1 signals for their ability to target fluorescent proteins in diverse plant species. Transient assays following microprojectile bombardment showed that the six amino acid PTS1 sequence (RAVARL) from spinach glycolate oxidase effectively targets green fluorescent fusion protein to the leaf peroxisomes in all 20 crops tested, including four monocots (sugarcane, wheat, corn and onion) and 16 dicots (carrot, cucumber, broccoli, tomato, lettuce, turnip, radish, cauliflower, cabbage, capsicum, celery, tobacco, petunia, beetroot, eggplant and coriander). Similarly, results indicated that the 10 amino acid PTS1 sequence (IHHPRELSRL) from pumpkin malate synthase effectively targets red fluorescent fusion protein to the leaf peroxisomes in all four crops tested including monocot (sugarcane) and dicot (cabbage, celery and pumpkin) species. These signal sequences should be useful metabolic engineering tools to direct recombinant proteins to the leaf peroxisomes in diverse plant species of biotechnological interest. PMID:22386008

  11. Retrieval of spinach crop parameters by microwave remote sensing with back propagation artificial neural networks: A comparison of different transfer functions

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Pandey, A.; Singh, K. P.; Singh, V. P.; Mishra, R. K.; Singh, D.

    2012-08-01

    Back propagation artificial natural network (BPANN) is a well known and widely used machine learning methodology in the field of remote sensing. In this paper an attempt is made to retrieve the spinach crop parameters like biomass, leaf area index, average plant height and soil moisture content by using the X-band scattering coefficients with BPANN at different growth stages of this crop. The maturity age of this crop was found to be 45 days from the date of sowing. After 45 days from the date of sowing, this crop was cut at a certain height for production. Then, it is a point of interest to investigate the microwave response of variation in production. Significant variations in all the crop parameters were observed after cutting the crop and consequently made the problem more critical. Our work confirms the utility of BPANN in handling such a non-linear data set. The BPANN is essentially a network of simple processing nodes arranged into different layers as input, hidden and the output. The input layer propagates components of a particular input vector after weighting these with synaptic weights to each node in the hidden layer. At each node, these weighted input vector components are added. Each hidden layer computes output corresponding to these weighted sum through a non-linear/linear function (e.g. LOGSIG, TANSIG and PURLIN). These functions are known as transfer functions. Thus, each of the hidden layer nodes compute output values, which become inputs to the nodes of the output layer. At nodes of output layer also a weighted sum of outputs of previous layer (hidden layer) are obtained and processed through a transfer function. Thus, the output layer nodes compute the network output for the particular input vector. In this paper, output nodes use linear transfer function. Different transfer functions e.g. TANSIG, LOGSIG and PURELIN were used and the performance of the ANN was optimized by changing the number of neurons in the hidden layers. The present analysis suggests the need of critical analysis of the BPANN in terms of selection of the best transfer function and other network parameters for the better results.

  12. Isolation and characterization of a cDNA encoding the SecA protein from spinach chloroplasts. Evidence for azide resistance of Sec-dependent protein translocation across thylakoid membranes in spinach.

    PubMed

    Berghfer, J; Karnauchov, I; Herrmann, R G; Klsgen, R B

    1995-08-01

    Thylakoid membranes of chloroplasts in higher plants harbor different pathways for the translocation of proteins. One of these routes is related to the prokaryotic Sec pathway, which mediates the secretion of particular proteins into the periplasmic space and involves the SecA protein as an essential component. We have isolated a full size cDNA of 3739 nucleotides encoding the SecA homologue from spinach. It contains an open reading frame of 1036 codons corresponding to a polypeptide with a calculated mass of 117 kDa. The deduced amino acid sequence shows between 43 and 49% identity to SecA proteins from bacteria and lower algae and 62% identity to SecA of the cyanobacterium Synechococcus sp. PCC7942. Compared with the Escherichia coli protein, spinach SecA carries an amino-terminal extension of approximately 80 residues. In organello experiments performed with the protein made in vitro by transcription of the cDNA and cell-free translation of the resulting RNA showed that this extension comprises a transit peptide that mediates the import of the protein into the chloroplast. The processed product of approximately 107 kDa accumulates predominantly in the stroma and to a lower extent associates with the thylakoid membrane. Comparably to E. coli, in which SecA activity can be inhibited by sodium azide, thylakoid translocation of a subset of lumenal proteins is sensitive to sodium azide in pea but not in spinach chloroplasts, suggesting that the latter contain an azide-resistant SecA variant. PMID:7629156

  13. 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 100ns-10s 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 10ns single turnover flash was modeled: the ??(t) amplitude (20mV) 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

  14. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  15. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface...

  16. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf surface. 29.3036 Section 29.3036 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface...

  17. 7 CFR 29.3036 - Leaf surface.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  18. Hormonal Regulation of Leaf Abscission

    PubMed Central

    Jacobs, William P.

    1968-01-01

    A review is given of the progress made during the last 6 years in elucidating the nature, locus of action, and transport properties of the endogenous hormones that control leaf abscission. PMID:16657014

  19. 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

  20. Deriving leaf chlorophyll content of green-leafy vegetables from hyperspectral reflectance

    NASA Astrophysics Data System (ADS)

    Xue, Lihong; Yang, Linzhang

    Different nitrogen (N) treatments of four common green-leafy vegetable varieties with different leaf color: lettuce ( Lactuca sativa L. var. crispa L.) with yellow green leaves, pakchoi ( Brassica chinensis L.) var. aijiaohuang in Chinese (AJH) with middle green leaves, spinach ( Spinacia oleracea L.) with green leaves and pakchoi ( B. chinensis L.) var. shanghaiqing in Chinese (SHQ) with dark green leaves, were carried out to achieve a wide range of chlorophyll content. The relationship of vegetable leaf hyperspectral response to its chlorophyll content was examined in this study. Almost all reported successful leaf chlorophyll indices in the literature were evaluated for their ability to predict the chlorophyll content in vegetable leaves. Some new indices based on the first derivative curve were also developed, and compared with the chlorophyll indices published. The results showed that most of the indices showed a strong relation with leaf chlorophyll content. In general, modified indices with the blue or near red edge wavelength performed better than their simple counterpart without modification, ratio indices performed a little better than normalized indices when chlorophyll expressed on area basis and reversed when chlorophyll expressed on fresh weight basis. A normalized derivative difference ratio (BND: (D722-D700)/(D722+D700) calibrated by Maire et al. [Maire, G., Francois, C., Dufrene, E., 2004. Towards universal broad leaf chlorophyll indices using PROSPECT simulated database and hyperspectral reflectance measurements. Remote Sensing of Environment 89 (1), 1-28]) gave the best results among all published indices in this study (RMSE=22.1 mg m -2), then the mSR-like indices with the RMSE between 22.6 and 23.0 mg m -2. The new indices EBAR (ratio of the area of red and blue, ∑ dRE/∑ dB), EBFN (normalized difference of the amplitude of red and blue, (dRE-dB)/(dRE+dB)) and EBAN (normalized difference of the area of red and blue, (∑ dRE-∑ dB)/(∑ dRE+∑ dB)) calculated with the derivatives also showed a good performance with the RMSE of 23.3, 24.15 and 24.33 mg m -2, respectively. The study suggests that spectral reflectance measurements hold promise for the assessment of chlorophyll content at the leaf level for green-leafy vegetables. Further investigation is needed to evaluate the effectiveness of such techniques on other vegetable varieties or at the canopy level.

  1. 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

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

  3. 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

  4. 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

  5. Mechanism of nano-anatase TiO2 on promoting photosynthetic carbon reaction of spinach: inducing complex of rubisco-rubisco activase.

    PubMed

    Gao, Fengqing; Hong, Fashui; Liu, Chao; Zheng, Lei; Su, Mingyu; Wu, Xiao; Yang, Fan; Wu, Cheng; Yang, Ping

    2006-01-01

    Having a photocatalyzed characteristic, our previous research had proved that nano-anatase TiO2 is closely related to the photosynthesis of spinach. It could not only improve the light absorbance and the transformation from light energy to electron energy and to active chemical energy but also promote carbon dioxide (CO2) assimilation of spinach. However, the mechanism of carbon reaction promoted by nano-anatase TiO2 remains largely unclear. By electrophoresis and Western blot methods, the results of the experiments proved that Rubisco from the nano-anatase TiO2-treated spinach during the extraction procedure of Rubisco was found to consist of Rubisco and a heavier molecular-mass protein (about 1,200 kDa) comprising both Rubisco and Rubisco activase. The Rubisco carboxylase activity was 2.67 times that of Rubisco from the control and it could hydrolyze ATP in the same manner as Rubisco activase. The total sulfhydryl groups and available sulfhydryl groups of the Rubisco were 32 -SH and 21 -SH per mole of enzyme more than those of the Rubisco purified from the control, respectively. The circular dichroism spectra showed that the secondary structure of Rubisco from the nano-anatase TiO2-treated spinach was very different from Rubisco of the control. It suggested that the mechanism of nano-anatase TiO2 activating Rubisco of spinach was that the complex of Rubsico and Rubisco activase was induced in spinach, which promoted Rubsico carboxylation and increased the rate of photosynthetic carbon reaction. PMID:16943609

  6. Multifactorial effects of ambient temperature, precipitation, farm management, and environmental factors determine the level of generic Escherichia coli contamination on preharvested spinach.

    PubMed

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

    2015-04-01

    A repeated cross-sectional study was conducted to identify farm management, environment, weather, and landscape factors that predict the count of generic Escherichia coli on spinach at the preharvest level. E. coli was enumerated for 955 spinach samples collected on 12 farms in Texas and Colorado between 2010 and 2012. Farm management and environmental characteristics were surveyed using a questionnaire. Weather and landscape data were obtained from National Resources Information databases. A two-part mixed-effect negative binomial hurdle model, consisting of a logistic and zero-truncated negative binomial part with farm and date as random effects, was used to identify factors affecting E. coli counts on spinach. Results indicated that the odds of a contamination event (non-zero versus zero counts) vary by state (odds ratio [OR] = 108.1). Odds of contamination decreased with implementation of hygiene practices (OR = 0.06) and increased with an increasing average precipitation amount (mm) in the past 29 days (OR = 3.5) and the application of manure (OR = 52.2). On contaminated spinach, E. coli counts increased with the average precipitation amount over the past 29 days. The relationship between E. coli count and the average maximum daily temperature over the 9 days prior to sampling followed a quadratic function with the highest bacterial count at around 24C. These findings indicate that the odds of a contamination event in spinach are determined by farm management, environment, and weather factors. However, once the contamination event has occurred, the count of E. coli on spinach is determined by weather only. PMID:25636850

  7. Multifactorial Effects of Ambient Temperature, Precipitation, Farm Management, and Environmental Factors Determine the Level of Generic Escherichia coli Contamination on Preharvested Spinach

    PubMed Central

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

    2015-01-01

    A repeated cross-sectional study was conducted to identify farm management, environment, weather, and landscape factors that predict the count of generic Escherichia coli on spinach at the preharvest level. E. coli was enumerated for 955 spinach samples collected on 12 farms in Texas and Colorado between 2010 and 2012. Farm management and environmental characteristics were surveyed using a questionnaire. Weather and landscape data were obtained from National Resources Information databases. A two-part mixed-effect negative binomial hurdle model, consisting of a logistic and zero-truncated negative binomial part with farm and date as random effects, was used to identify factors affecting E. coli counts on spinach. Results indicated that the odds of a contamination event (non-zero versus zero counts) vary by state (odds ratio [OR] = 108.1). Odds of contamination decreased with implementation of hygiene practices (OR = 0.06) and increased with an increasing average precipitation amount (mm) in the past 29 days (OR = 3.5) and the application of manure (OR = 52.2). On contaminated spinach, E. coli counts increased with the average precipitation amount over the past 29 days. The relationship between E. coli count and the average maximum daily temperature over the 9 days prior to sampling followed a quadratic function with the highest bacterial count at around 24°C. These findings indicate that the odds of a contamination event in spinach are determined by farm management, environment, and weather factors. However, once the contamination event has occurred, the count of E. coli on spinach is determined by weather only. PMID:25636850

  8. Leaf exsertion, leaf elongation, and leaf senescence in Eriophorum vaginatum and Carex Bigelowii

    SciTech Connect

    Shaver, G.R.; Yandow, T.; Laundre, J.

    1990-01-01

    Most of the common sedges of arctic vegetation show a pattern of leaf production in which the exsertion and elongation of new leaves is more or less simultaneous with the senescence of old leaves. The present study was designed to increase our understanding of the variability sequential leaf production by arctic sedges, and to determine some of the controls on that variability. We did this in two ways: first, we compared the sequential patterns of leaf growth and senescence in E. vaginatum with those of Carex Bigelowii Torr. at two tussock tundra sites near Toolik Lake on the North Slope of Alaska. Second, we compared the responses of leaf growth in these species in control and fertilized plots and in two microenvironments thought to differ sharply in nutrient availability and total productivity. 29 refs., 28 figs., 2 tabs.

  9. Temperature and pH effects on chloroplastic respiration of glucose and fructose in spinach

    SciTech Connect

    Singh, K.K.; Gibbs, M. )

    1993-05-01

    Respiration was monitored principally as CO[sub 2] release in the darkened intact spinach chloroplast supplied with [sup 14]C-glucose and [sup 14]C-fructose. The rate of flucose respiration, optimum pH 7.5, increased from 15[degrees]C up to 40[degrees]C and then decreased in the presence of added ATP. In the absence of ATP, the optimum temperature for CO[sub 2] release was 25 [degrees]C and then decreased. At optimum pH 8.5, both in the absence and presence of ATP, the rate increased up to 25[degrees]C and then decreased. The negative effect of high temperature was not reversed when the chloroplast was returned to 25[degrees]C. Higher temperature (40[degrees]C vs 15[degrees]C) and higher pH (8.5 vs 7.5) increased radioactivity into starch and decreased radioactivity in CO[sub 2]. The rate of fructose respiration, optimum pH 7.5 but also at pH 8.5, increased CO[sub 2] release from 15[degrees]C to 40[degrees]C and then decreased both in the absence and presence of externally supplied ATP. Temperature and pH has no effect on radioactivity in starch and CO[sub 2] when fructose was substrate. The difference in results between glucose and fructose may reflect the localization of fructokinase in the stroma and glucokinase both in the stroma and cytosolic side of the outer chloroplastic membrane. It may be also reflect the equilibrium of phosphohexose isomerase favoring fructose-6-P.

  10. Formation of the Fe-S cluster of ferredoxin in lysed spinach chloroplasts. [Spinacia oleracea

    SciTech Connect

    Takahashi, Yasuhiro; Mitsui, Akira; Matsubara, Hiroshi )

    1991-01-01

    In vitro formation of the {sup 35}S-labeled Fe-S cluster of ferredoxin (Fd) has been achieved by incubating apo-Fd and ({sup 35}S)cysteine with osmotically lysed chloroplasts of spinach (Spinacia oleracea). Correct integration of the {sup 35}S-labeled Fe-S cluster into Fd was verified on the basis of the following: (a) Under nondenaturing conditions, {sup 35}S-labeled holo-Fd showed the same electrophoretic mobility as authentic holo-Fd; (b) {sup 35}S-labeled holo-Fd showed an ability to bind Fd-NADP{sup +} reductase; (c) the {sup 35}S-labeled moiety was removed from the Fd polypeptide by TCA treatment but not by 2-mercaptoethanol treatment; (d) externally added pea II apo-Fd was converted to {sup 35}S-labeled holo-Fd. This reconstitution was dependent on both ATP and light, and formation of the {sup 35}S-labeled Fe-S cluster was observed upon addition of ATP or when an ATP generation-system was constructed in the light. In contrast, ATP-consuming systems abolished the Fe-S cluster formation. A non-hydrolyzable ATP analog was unable to serve as an ATP substitute, indicating the requirement of ATP hydrolysis for cluster formation. GTP was able to substitute for ATP, but CTP and UTP were less effective. Fe-S cluster formation in lysed chloroplasts was stimulated by light even in the presence of added ATP. Light stimulation was inhibited by DCMU or methyl viologen but not by NH{sub 4}{sup +}. NADPH was able to substitute for light, indicating that light energy is required for the production of reducing compounds such as NADPH in addition to the generation of ATP.

  11. Thermal denaturation of spinach plastocyanin: effect of copper site oxidation state and molecular oxygen.

    PubMed

    Sandberg, Anders; Harrison, David J; Karlsson, B Göran

    2003-09-01

    The thermal denaturation of the cupredoxin plastocyanin (PC) from spinach has been studied with the aim of improving the understanding of factors involved in the conformational stability of antiparallel beta-sheet proteins. Studies using differential scanning calorimetry have been complemented with nuclear magnetic resonance spectroscopy, absorbance spectroscopy, dynamic light scattering, and mass spectrometry in elucidation of the effect of the copper-site oxidation state on the irreversible thermal denaturation process. Our results indicate that copper-catalyzed oxidation of the metal-ligating cysteine is the sole factor resulting in thermal irreversibility. However, this can be prevented in reduced protein by the removal of molecular oxygen. Application of a two-state equilibrium transition model to the folding process thus allowed the extraction of thermodynamic parameters for the reduced protein (Delta(trs)H = 494 kJ mol(-1), DeltaH(vH) = 343 kJ mol(-1), and T(m) = 71 degrees C). However, anaerobically denatured oxidized protein and all aerobically denatured species undergo covalent modification as a result of the copper-catalyzed oxidation of the metal-ligating cysteine residue resulting in the formation of both oxidized monomers and disulfide-linked dimers. On the basis of these results, a general mechanism for the irreversible thermal denaturation of cupredoxins is proposed. The results presented here also indicate that PC, as opposed to the previously characterized homologous protein azurin, unfolds via at least one significantly populated intermediate state (DeltaH(vH)/Delta(trs)H = 0.7) despite the almost identical native state topologies of these proteins. These findings will aid the characterization of the stability of PC and other cupredoxins and possibly of all cysteine-ligating metal-binding proteins. PMID:12939160

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

    PubMed

    Santos, J; Oliveira, M B P P; Ibez, 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

  13. Differential sensitivity of spinach and amaranthus to enhanced UV-B at varying soil nutrient levels: association with gas exchange, UV-B-absorbing compounds and membrane damage.

    PubMed

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

    2013-07-01

    The metabolic reasons associated with differential sensitivity of C3 and C4 plant species to enhanced UV-B under varying soil nutrient levels are not well understood. In the present study, spinach (Spinacia oleracea L. var All Green), a C3 and amaranthus (Amaranthus tricolor L. var Pusa Badi Chaulai), a C4 plant were subjected to enhanced UV-B (280-315nm; 7.2kJm(-2)day(-1)) over ambient under varying soil nutrient levels. The nutrient amendments were recommended Nitrogen (N), Phosphorus (P), Potassium (K), 1.5 recommended NPK, 1.5 recommended N and 1.5 recommended K. Enhanced UV-B negatively affected both the species at all nutrient levels, but the reductions varied with nutrient concentration and combinations. Reductions in photosynthetic rate, stomatal conductance and chlorophyll content were significantly more in spinach compared with amaranthus. The reduction in photosynthetic rate was maximum at 1.5 recommended K and minimum in 1.5 NPK amended plants. The oxidative damage to membranes measured in terms of malondialdehyde content was significantly higher in spinach compared with amaranthus. Enhanced UV-B reduced SOD activity in both the plants except in amaranthus at 1.5 recommended K. POX activity increased under enhanced UV-B at all nutrient levels in amaranthus, but only at 1.5 K in spinach. Amaranthus had significantly higher UV-B-absorbing compounds than spinach even under UV-B stress. Lowest reductions in yield and total biomass under enhanced UV-B compared with ambient were observed in amaranthus grown at 1.5 recommended NPK. Enhanced UV-B did not significantly change the nitrogen use efficiency in amaranthus at all NPK levels, but reduced in spinach except at 1.5 K. These findings suggest that the differential sensitivity of the test species under enhanced UV-B at varying nutrient levels is due to varying antioxidative and UV-B screening capacity, and their ability to utilize nutrients. Amaranthus tolerated enhanced UV-B stress more than spinach at all nutrient levels and 1.5 recommended NPK lowered the sensitivity maximally to enhanced UV-B with respect to photosynthesis, biomass and yield. PCA score has also confirmed the lower sensitivity of amaranthus compared with spinach with respect to the measured physiological and biochemical parameters. PMID:23686471

  14. 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 ...

  15. How to pattern a leaf.

    PubMed

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

    2012-01-01

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

  16. 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...

  17. Relationship between fresh-packaged spinach leaves exposed to continuous light or dark and bioactive contents: Effects of cultivar, leaf size, and storage duration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Human-health benefits derived from consumption of fruits and vegetables are due to the many bioactive compounds found in produce. The concentrations of these bioactive compounds are heavily influenced by genetics (i.e. cultivar) and environment, especially the many pigments and vitamins that can ch...

  18. Photoregulation of fructose and glucose respiration in the intact chloroplasts of Chlamydomonas reinhardtii F-60 and spinach

    SciTech Connect

    Singh, K.K.; Changguo Chen; Gibbs, M. )

    1993-04-01

    The photoregulation of chloroplastic respiration was studied by monitoring in darkness and in light the release of [sup 14]CO[sub 2] from whole chloroplasts of Chlamydomonas reinhardtii F-60 and spinach (Spinacia oleracea L.) supplied externally with [[sup 14]C]glucose and [[sup 14]C]fructose, respectively. CO[sub 2] release was inhibited more than 90% in both chloroplasts by a light intensity of 4 W m[sup [minus]2]. Oxidants, oxaloacetate in Chlamydomonas, nitrite in spinach, and phenazine methosulfate in both chloroplasts, reversed the inhibition. The onset of the photoinhibitory effect on CO[sub 2] release was relatively rapid compared to the restoration of CO[sub 2] release following illumination. In both darkened chloroplasts, dithiothreitol inhibited release. Of the four enzymes (fructokinase, phosphoglucose isomerase, glucose-6-P dehydrogenase, and gluconate-6-P dehydrogenase) in the pathway catalyzing the release of CO[sub 2] from fructose, only glucose-6-P dehydrogenase was deactivated by light and by dithiothreitol. 33 refs., 3 figs., 4 tabs.

  19. Molecular characterization of PsbW, a nuclear-encoded component of the photosystem II reaction center complex in spinach.

    PubMed Central

    Lorković, Z J; Schröder, W P; Pakrasi, H B; Irrgang, K D; Herrmann, R G; Oelmüller, R

    1995-01-01

    We describe the isolation and characterization of cDNAs encoding the precursor polypeptide of the 6.1-kDa polypeptide associated with the reaction center core of the photosystem II complex from spinach. PsbW, the gene encoding this polypeptide, is present in a single copy per haploid genome. The mature polypeptide with 54 amino acid residues is characterized by a hydrophobic transmembrane segment, and, although an intrinsic membrane protein, it carries a bipartite transit peptide of 83 amino acid residues which directs the N terminus of the mature protein into the chloroplast lumen. Thylakoid integration of this polypeptide does not require a delta pH across the membrane, nor is it azide-sensitive, suggesting that the polypeptide chain inserts spontaneously in an as yet unknown way. The PsbW mRNA levels are light regulated. Similar to cytochrome b559 and PsbS, but different from the chlorophyll-complexing polypeptides D1, D2, CP43, and CP47 of photosystem II, PsbW is present in etiolated spinach seedlings. Images Fig. 1 Fig. 4 Fig. 5 Fig. 6 PMID:7568046

  20. 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

  1. Mild Fe-deficiency improves biomass production and quality of hydroponic-cultivated spinach plants (Spinacia oleracea L.).

    PubMed

    Jin, Chong-Wei; Liu, Yue; Mao, Qian-Qian; Wang, Qian; Du, Shao-Ting

    2013-06-15

    It is of great practical importance to improve yield and quality of vegetables in soilless cultures. This study investigated the effects of iron-nutrition management on yield and quality of hydroponic-cultivated spinach (Spinacia oleracea L.). The results showed that mild Fe-deficient treatment (1 ?M FeEDTA) yielded a greater biomass of edible parts than Fe-omitted treatment (0 ?M FeEDTA) or Fe-sufficient treatments (10 and 50 ?M FeEDTA). Conversely, mild Fe-deficient treatment had the lowest nitrate concentration in the edible parts out of all the Fe treatments. Interestingly, all the concentrations of soluble sugar, soluble protein and ascorbate in mild Fe-deficient treatments were higher than Fe-sufficient treatments. In addition, both phenolic concentration and DPPH scavenging activity in mild Fe-deficient treatments were comparable with those in Fe-sufficient treatments, but were higher than those in Fe-omitted treatments. Therefore, we concluded that using a mild Fe-deficient nutrition solution to cultivate spinach not only would increase yield, but also would improve quality. PMID:23497875

  2. [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

  3. Research of the relationship between delayed fluorescence and net photosynthesis rate in spinach under NaCl stress

    NASA Astrophysics Data System (ADS)

    Zhang, Lingrui; Xing, Da

    2006-09-01

    Under NaCl stress conditions, the relationship between delayed fluorescence (DF) and net photosynthesis rate (Pn) in detached leaves of spinach (Spinacia oleracea L.) was surveyed. Results showed that the changes in DF intensity of the spinach leaves directly exposed to different NaCl concentrations demonstrated considerably high consistency with that in Pn. Incubation of the leaves in 200mmol/L NaCl induced a gradual increase and subsequent decline of the DF intensity and Pu, whereas incubation of the leaves in 300mmol/L NaCl induced a continuous decline of the DF intensity and Pn, suggesting that DF bad the same response to duration of treatment of different NaC1 concentrations with Pn. Both DF and Pn showed maximal Ca 2+ antagonism effects on stress of high concentration NaC1 when the concentration of CaC1 II reached l5mmolfL. All the results demonstrated that DF has an excellent correlation with Pn and can be used as a sensitive test for the state of photosynthetic apparatus under salt stress physiology.

  4. Transfer of Escherichia coli O157:H7 to spinach by house flies, Musca domestica (Diptera: Muscidae).

    PubMed

    Wasala, Lakmini; Talley, Justin L; Desilva, Udaya; Fletcher, Jacqueline; Wayadande, Astri

    2013-04-01

    Filth flies are known mechanical vectors of pathogenic bacteria in hospital and restaurant settings, but their role as vectors for disseminating microbes to plants has not been demonstrated. Escherichia coli O157:H7 deposition by flies onto spinach was studied using molecular, microbiological, and microscopy techniques. Relative quantitative polymerase chain reaction studies showed that bacteria acquired by flies from contaminated cattle manure and deposited in regurgitation spots on leaves survived and multiplied. Scanning electron microscopy of the regurgitation spots of flies exposed to manure inoculated with E. coli suggested the multiplication of bacteria-like organisms within the spots. This finding implies that the bacteria were active and is consistent with a hypothesis that regurgitation spots serve as a nutrition source allowing E. coli O157:H7 to survive on the spinach phylloplane. E. coli O157:H7 persisted on fly body surfaces up to 13 days after exposure to acquisition sources, suggesting that fly cuticular surfaces are conducive to the growth of this pathogen. These results are consistent with the hypothesis of bioenhanced transmission of human pathogens by house flies and suggest that filth flies may affect the microbial safety of fresh produce. PMID:23425236

  5. 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

  6. Biophysical control of leaf temperature

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  7. Influence of Adenosine Phosphates and Magnesium on Photosynthesis in Chloroplasts from Peas, Sedum, and Spinach 1

    PubMed Central

    Piazza, George J.; Gibbs, Martin

    1983-01-01

    14CO2 photoassimilation in the presence of MgATP, MgADP, and MgAMP was investigated using intact chloroplasts from Sedum praealtum, a Crassulacean acid metabolism plant, and two C3 plants: spinach and peas. Inasmuch as free ATP, ADP, AMP, and uncomplexed Mg2+ were present in the assays, their influence upon CO2 assimilation was also examined. Free Mg2+ was inhibitory with all chloroplasts, as were ADP and AMP in chloroplasts from Sedum and peas. With Sedum chloroplasts in the presence of ADP, the time course of assimilation was linear. However, with pea chloroplasts, ADP inhibition became progressively more severe, resulting in a curved time course. ATP stimulated assimilation only in pea chloroplasts. MgATP and MgADP stimulated assimilation in all chloroplasts. ADP inhibition of CO2 assimilation was maximal at optimum orthophosphate concentrations in Sedum chloroplasts, while MgATP stimulation was maximal at optimum or below optimum concentrations of orthophosphate. MgATP stimulation in peas and Sedum and ADP inhibition in Sedum were not sensitive to the addition of glycerate 3-phosphate (PGA). PGA-supported O2 evolution by pea chloroplasts was not inhibited immediately by ADP; the rate of O2 evolution slowed as time passed, corresponding to the effect of ADP on CO2 assimilation, and indicating that glycerate 3-phosphate kinase was a site of inhibition. Likewise, upon the addition of AMP, inhibition of PGA-dependent O2 evolution became more severe with time. This did not mirror CO2 assimilation, which was inhibited immediately by AMP. In Sedum chloroplasts, PGA-dependent O2 evolution was not inhibited by ADP and AMP. In chloroplasts from peas and Sedum, the magnitude of MgADP and MgATP stimulation of PGA-dependent O2 evolution was not much larger than that given by ATP, and it was much smaller than MgATP stimulation of CO2 assimilation. Analysis of stromal metabolite levels by anion exchange chromatography indicated that ribulose 1,5-bisphosphate carboxylase was inhibited by ADP and stimulated by MgADP in Sedum chloroplasts. The appearance of label in the medium was measured when [U-14C] ADP-loaded Sedum chloroplasts were challenged with ATP, ADP, or AMP and their Mg2+ complexes. The rate of back exchange was stimulated by the presence of Mg2+. This suggests that ATP, ADP, and AMP penetrate the chloroplast slower than their Mg2+ complexes. A portion of the CO2 assimilation and O2 evolution data could be explained by differential penetration rates, and other proposals were made to explain the remainder of the observations. PMID:16662888

  8. Influence of adenosine phosphates and magnesium on photosynthesis in chloroplasts from peas, sedum, and spinach.

    PubMed

    Piazza, G J; Gibbs, M

    1983-03-01

    (14)CO(2) photoassimilation in the presence of MgATP, MgADP, and MgAMP was investigated using intact chloroplasts from Sedum praealtum, a Crassulacean acid metabolism plant, and two C(3) plants: spinach and peas. Inasmuch as free ATP, ADP, AMP, and uncomplexed Mg(2+) were present in the assays, their influence upon CO(2) assimilation was also examined. Free Mg(2+) was inhibitory with all chloroplasts, as were ADP and AMP in chloroplasts from Sedum and peas. With Sedum chloroplasts in the presence of ADP, the time course of assimilation was linear. However, with pea chloroplasts, ADP inhibition became progressively more severe, resulting in a curved time course. ATP stimulated assimilation only in pea chloroplasts. MgATP and MgADP stimulated assimilation in all chloroplasts. ADP inhibition of CO(2) assimilation was maximal at optimum orthophosphate concentrations in Sedum chloroplasts, while MgATP stimulation was maximal at optimum or below optimum concentrations of orthophosphate. MgATP stimulation in peas and Sedum and ADP inhibition in Sedum were not sensitive to the addition of glycerate 3-phosphate (PGA).PGA-supported O(2) evolution by pea chloroplasts was not inhibited immediately by ADP; the rate of O(2) evolution slowed as time passed, corresponding to the effect of ADP on CO(2) assimilation, and indicating that glycerate 3-phosphate kinase was a site of inhibition. Likewise, upon the addition of AMP, inhibition of PGA-dependent O(2) evolution became more severe with time. This did not mirror CO(2) assimilation, which was inhibited immediately by AMP. In Sedum chloroplasts, PGA-dependent O(2) evolution was not inhibited by ADP and AMP. In chloroplasts from peas and Sedum, the magnitude of MgADP and MgATP stimulation of PGA-dependent O(2) evolution was not much larger than that given by ATP, and it was much smaller than MgATP stimulation of CO(2) assimilation. Analysis of stromal metabolite levels by anion exchange chromatography indicated that ribulose 1,5-bisphosphate carboxylase was inhibited by ADP and stimulated by MgADP in Sedum chloroplasts.The appearance of label in the medium was measured when [U-(14)C] ADP-loaded Sedum chloroplasts were challenged with ATP, ADP, or AMP and their Mg(2+) complexes. The rate of back exchange was stimulated by the presence of Mg(2+). This suggests that ATP, ADP, and AMP penetrate the chloroplast slower than their Mg(2+) complexes. A portion of the CO(2) assimilation and O(2) evolution data could be explained by differential penetration rates, and other proposals were made to explain the remainder of the observations. PMID:16662888

  9. Oxygen-18 and Deuterium Labeling Studies of Choline Oxidation by Spinach and Sugar Beet 1

    PubMed Central

    Lerma, Claudia; Hanson, Andrew D.; Rhodes, David

    1988-01-01

    Chenopods synthesize betaine by a two-step oxidation of choline: choline ? betaine aldehyde ? betaine. The pathway is chloroplastic; the first step has been shown in isolated spinach (Spinacia oleracea L.) chloroplasts to be O2- and light-dependent, the role of light being to provide reducing power (P Weigel, EA Weretilnyk, AD Hanson 1988 Plant Physiol 86: 54-60). Here, we report use of in vivo18O- and 2H-labeling in conjunction with fast atom bombardment mass spectrometry to test for two hypothetical choline-oxidizing reactions that would explain the observed requirements for O2 and reductant: a desaturase or an oxygenase. Simple syntheses for 2H3-choline, 2H3, 18O-choline, and 2H3, 18O-betaine are given. A desaturase mechanism was sought by giving choline deuterated at the 2-carbon, or choline unlabeled at this position together with 2H2O and by analyzing newly synthesized betaine. About 15% of the 2H at C-2 was lost during oxidation of choline to betaine, and about 10% of the betaine made in the presence of 50% 2H2O was monodeuterated. These small effects are more consistent with chemical exchange than with a desaturase, because 10 to 15% losses of 2H from the C-2 position also occurred if choline was converted to betaine by a purified bacterial choline oxidase. To test for an oxygenase, the incorporation of 18O from 18O2 into newly synthesized betaine was compared with that from 18O-labeled choline, in light and darkness. Incorporation of 18O from 18O-choline was readily detectable and varied from about 15 to 50% of the theoretical maximum value; the 18O losses were attributable to exchange of the intermediate betaine aldehyde with water. In darkness, incorporation of 18O from 18O2 approached that from 18O-choline, but in the light was severalfold lower, presumably due to isotopic dilution by photosynthetic 16O2. These data indicate that the chloroplast choline-oxidizing enzyme is an oxygenase. PMID:16666370

  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. Transcriptome and phenotypic difference of Escherichia coli O157:H7 isolates related to the 2006 spinach-associated outbreak reveals variants in the bag

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Food-borne outbreaks of Escherichia coli O157:H7 illness linked to the consumption of ready-to-eat leafy vegetables, such as lettuce and spinach, are a mounting concern. Likely sources of pre-harvest contamination are soil and water that become contaminated via cattle and feral pigs in the proximit...

  12. D-ribulose-5-phosphate 3-epimerase: Cloning and heterologous expression of the spinach gene, and purification and characterization of the recombinant enzyme

    SciTech Connect

    Chen, Y.R.; Hartman, F.C.; Lu, T.Y.S.; Larimer, F.W.

    1998-09-01

    The authors have achieved, to their knowledge, the first high-level heterologous expression of the gene encoding D-ribulose-5-phosphate 3-epimerase from any source, thereby permitting isolation and characterization of the epimerase as found in photosynthetic organisms. The extremely labile recombinant spinach (Spinacia oleracea L.) enzyme was stabilized by DL-{alpha}-glycerophosphate or ethanol and destabilized by D-ribulose-5-phosphate or 2-mercaptoethanol. Despite this lability, the unprecedentedly high specific activity of the purified material indicates that the structural integrity of the enzyme is maintained throughout isolation. Ethylenediaminetetraacetate and divalent metal cations did not affect epimerase activity, thereby excluding a requirement for the latter in catalysis. As deduced from the sequence of the cloned spinach gene and the electrophoretic mobility under denaturing conditions of the purified recombinant enzyme, its 25-kD subunit size was about the same as that of the corresponding epimerases of yeast and mammals. However, in contrast to these other species, the recombinant spinach enzyme was octameric rather than dimeric, as assessed by gel filtration and polyacrylamide gel electrophoresis under nondenaturing conditions. Western-blot analyses with antibodies to the purified recombinant enzyme confirmed that the epimerase extracted from spinach leaves is also octameric.

  13. Effect of Nd{sup 3+} ion on carboxylation activity of ribulose-1,5-bisphosphate carboxylase/oxygenase of spinach

    SciTech Connect

    Liu Chao; Hong Fashui . E-mail: Hongfsh_cn@sina.com; Wu Kang; Ma, Hong-bing; Zhang Xueguang; Hong Chengjiao; Wu Cheng; Gao Fengqing; Yang Fan; Zheng Lei; Wang Xuefeng; Liu Tao; Xie Yaning; Xu Jianhua; Li Zhongrui

    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{sup 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 1200 kD) 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{sup 3+}-treated spinach was different from that of the control. Extended X-ray absorption fine structure study of the 'Rubisco' purified from the Nd{sup 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 2.89 A, respectively.

  14. The efficacy of sanitizer and ultrasound combined treatments on reduction of Escherichia coli O157:H7 surrogate population on spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The recent outbreak of Escherichia coli O157:H7 infections on bagged spinach reaffirmed the importance and challenges of produce safety. Current washing processes in industrial scale operations can only achieve 1- to 2-log CFU/g reduction in microbial populations. More effective post-harvest interve...

  15. Mathematical modeling and numerical analysis of the growth of Non-O157 shiga toxin-producing Escherichia coli in spinach leaves

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to investigate the growth of non-O157 Shiga toxin-producing Escherichia coli (STEC) in spinach leaves and to develop kinetic models to describe the bacterial growth. Six serogroups of non-O157 STEC, including O26, O45, O103, O111, O121, and O145, were used in the growth stu...

  16. 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...

  17. 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...

  18. 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...

  19. d-Ribulose-5-Phosphate 3-Epimerase: Cloning and Heterologous Expression of the Spinach Gene, and Purification and Characterization of the Recombinant Enzyme1

    PubMed Central

    Chen, Yuh-Ru; Hartman, Fred C.; Lu, Tse-Yuan S.; Larimer, Frank W.

    1998-01-01

    We have achieved, to our knowledge, the first high-level heterologous expression of the gene encoding d-ribulose-5-phosphate 3-epimerase from any source, thereby permitting isolation and characterization of the epimerase as found in photosynthetic organisms. The extremely labile recombinant spinach (Spinacia oleracea L.) enzyme was stabilized by dl-?-glycerophosphate or ethanol and destabilized by d-ribulose-5-phosphate or 2-mercaptoethanol. Despite this lability, the unprecedentedly high specific activity of the purified material indicates that the structural integrity of the enzyme is maintained throughout isolation. Ethylenediaminetetraacetate and divalent metal cations did not affect epimerase activity, thereby excluding a requirement for the latter in catalysis. As deduced from the sequence of the cloned spinach gene and the electrophoretic mobility under denaturing conditions of the purified recombinant enzyme, its 25-kD subunit size was about the same as that of the corresponding epimerases of yeast and mammals. However, in contrast to these other species, the recombinant spinach enzyme was octameric rather than dimeric, as assessed by gel filtration and polyacrylamide gel electrophoresis under nondenaturing conditions. Western-blot analyses with antibodies to the purified recombinant enzyme confirmed that the epimerase extracted from spinach leaves is also octameric. PMID:9733539

  20. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In response to U.S. foodborne illnesses caused by contaminated spinach, growers have adopted regulations stated in the California Leafy Greens Marketing Agreement (LGMA). The LGMA permits a maximum population mean of 126 Most Probable Number (MPN) generic E. coli per 100 ml irrigation water. These...

  2. Influence of the interaction between light intensity and CO2 concentration on productivity and quality of spinach (Spinacia oleracea L.) grown in fully controlled environment

    NASA Astrophysics Data System (ADS)

    Proietti, Simona; Moscatello, Stefano; Giacomelli, Gene A.; Battistelli, Alberto

    2013-09-01

    The effects of the factorial combination of two light intensities (200 and 800 μmol m-2 s-1) and two CO2 concentrations (360 and 800 ppm) were studied on the productivity and nutritional quality of spinach (Spinacia oleracea L.) grown under controlled environment. After 6 weeks within a growth chamber, spinach plants were sampled and analyzed for productivity and quality. There were no statistically significant interactions between the effects of light and CO2 for all of the variables studied, except for the nitrate and oxalic acid content of the leaves. High light and high CO2 independently one from the other, promoted spinach productivity, and the accumulation of ascorbic acid, while their interactive effect limited the accumulation of nitrate and oxalic acid in the spinach leaves. The results highlight the importance of considering the effects of the interaction among environmental variables on maximizing production and the nutritional quality of the food when cultivating and modeling the plant response in controlled environment systems such as for bioregenerative life support.

  3. 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 ...

  4. Behavior of Leaf Meristems and Their Modification

    PubMed Central

    Ichihashi, Yasunori; Tsukaya, Hirokazu

    2015-01-01

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

  5. 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.

  6. Respiration of sugars in spinach (Spinacia oleraces), maize (Zea mays), and Chlamydomonas reinhardtii F-60 chloroplasts with emphasis on the hexose kinases

    SciTech Connect

    Singh, K.K.; Chen, C.; Epstein, D.K.; Gibbs, M. )

    1993-06-01

    The role of hexokinase in carbohydrate degradation in isolated, intact chloroplasts was evaluated. This was accomplished by monitoring the evolution of [sup 14]CO[sub 2] from darkened spinach (Spinacia oleracea), maize (Zea mays) mesophyll, and Chlamydomonas reinhardtii chloroplasts externally supplied with [sup 14]C-labeled fructose, glucose, mannose, galactose, maltose, and ribose. Glucose and ribose were the preferred substrates with the Chlamydomonas and maize chloroplasts, respectively. The rate of CO[sub 2] release from fructose was about twice that from glucose in the spinach chloroplast. externally supplied ATP stimulated the rate of CO[sub 2] release. The pH optimum for CO[sub 2] release was 7.5 with ribose and fructose and 8.5 with glucose as substrates. Probing the outer membrane polypeptides of the intact spinach chloroplast with two proteases, trypsin and thermolysin, decreased [sup 14]CO[sub 2] release from glucose about 50% but had little effect when fructose was the substrate. Tryptic digestion decreased CO[sub 2] release from glucose in the Chlamydomonas chloroplast about 70%. [sup 14]CO[sub 2] evolution from [1-[sup 14]C]-glucose-6-phosphate in both chloroplasts was unaffected by treatment with trypsin. Enzymic analysis of the supernatant (stroma) of the lysed spinach chloroplast indicated a hexokinase active primarily with fructose but with some affinity for glucose. The pellet (membranal fraction) contained a hexokinase utilizing both glucose and fructose but with considerably less total activity than the stormal enzyme. Treatment with trypsin and thermolysin eliminated more than 50% of the glucokinase activity but had little effect on fructokinase activity in the spinach chloroplast. Tryptic digestion of the Chlamydomonas chloroplast resulted in a loss of about 90% of glucokinase activity. 34 refs., 2 figs., 6 tabs.

  7. 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?=?5.064kcal/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 (0.5mg/l) did not show a significant effect compared to control in inducing seed germination process. Further, higher levels of kinetin (>0.5mg/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

  8. LEAF: A Microcomputer Program for Constructing the Tukey Stem and Leaf Graph.

    ERIC Educational Resources Information Center

    Pascale, Pietro J.; Smith, Joseph

    1986-01-01

    This paper presents a BASIC microcomputer program that constructs the Tukey (1977) stem and leaf graph. Options within the LEAF program include a modified stem and leaf where the stem is split and a parallel stem and leaf graph where two separate sets of data are displayed from a common stem. (Author)

  9. 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 ...

  10. Light reflectance of leaf constituents

    NASA Technical Reports Server (NTRS)

    Gausman, H. W.

    1973-01-01

    It is shown how various leaf constituents differ in reflecting light over the 370- to 1100-nm wavelength interval. The premise tested is that refractive index discontinuities in leaves, other than air-cell interfaces, contribute to the reflectance of near-infrared light.-

  11. Exobasidium leaf and fruit spot

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. Analysis of Circadian Leaf Movements.

    PubMed

    Müller, Niels A; Jiménez-Gómez, José M

    2016-01-01

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

  13. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 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 tobacco and consists of loose and tangled whole or broken leaves....

  14. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves....

  15. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole...

  16. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 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 tobacco and consists of loose and tangled whole or broken leaves....

  17. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, 29.2601.)...

  18. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves....

  19. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  20. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  1. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture... Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves....

  2. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, 29.2351.)...

  3. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole...

  4. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  5. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, 29.2351.)...

  6. 7 CFR 29.2277 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and...

  7. 7 CFR 29.2278 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture... INSPECTION Standards Official Standard Grades for Virginia Fire-Cured Tobacco (u.s. Type 21) 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, 29.2351.)...

  8. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, 29.2601.)...

  9. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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

  10. 7 CFR 29.2530 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, 29.2601.)...

  11. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture... Type 95) 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves....

  12. 7 CFR 29.6023 - Leaf structure.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

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

  13. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture... Type 95) 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves....

  14. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole...

  15. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture... Type 95) 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed tobacco and consists of loose and tangled whole or broken leaves....

  16. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 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 tobacco and consists of loose and tangled whole or broken leaves....

  17. 7 CFR 29.2529 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  18. 7 CFR 29.3526 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  19. 7 CFR 29.3034 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  20. 7 CFR 29.6022 - Leaf scrap.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  1. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity....

  2. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity....

  3. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  4. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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

  5. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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

  6. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See...

  7. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  8. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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

  9. 7 CFR 29.3527 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  10. 7 CFR 29.3035 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  11. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  12. 7 CFR 29.1030 - Leaf structure.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

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

  13. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2013 CFR

    2013-01-01

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

  14. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2012 CFR

    2012-01-01

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

  15. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2011 CFR

    2011-01-01

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

  16. 7 CFR 29.3648 - Thin Leaf (C Group).

    Code of Federal Regulations, 2014 CFR

    2014-01-01

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

  17. Leafing patterns and leaf traits of four evergreen shrubs in the Patagonian Monte, Argentina

    NASA Astrophysics Data System (ADS)

    Campanella, Mara Victoria; Bertiller, Mnica B.

    2009-11-01

    We assessed leafing patterns (rate, timing, and duration of leafing) and leaf traits (leaf longevity, leaf mass per area and leaf-chemistry) in four co-occurring evergreen shrubs of the genus Larrea and Chuquiraga (each having two species) in the arid Patagonian Monte of Argentina. We asked whether species with leaves well-defended against water shortage (high LMA, leaf longevity, and lignin concentration, and low N concentration) have lower leaf production, duration of the leafing period, and inter-annual variation of leafing than species with the opposite traits. We observed two distinctive leafing patterns each related to one genus. Chuquiraga species produced new leaves concentrated in a massive short leafing event (5-48 days) while new leaves of Larrea species emerged gradually (128-258 days). Observed leafing patterns were consistent with simultaneous and successive leafing types previously described for woody plants. The peak of leaf production occurred earlier in Chuquiraga species (mid September) than in Larrea species (mid October-late November). Moreover, Chuquiraga species displayed leaves with the longest leaf lifespan, while leaves of Larrea species had the lowest LMA and the highest N and soluble phenolics concentrations. We also observed that only the leaf production of Larrea species increased in humid years. We concluded that co-occurring evergreen species in the Patagonian Monte displayed different leafing patterns, which were associated with some relevant leaf traits acting as plant defenses against water stress and herbivores. Differences in leafing patterns could provide evidence of ecological differentiation among coexisting species of the same life form.

  18. 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.

  19. Effect of Butyl 2-Hydroxy-3-Butynoate on Sunflower Leaf Photosynthesis and Photorespiration 1

    PubMed Central

    Doravari, Sudarsanam; Canvin, David T.

    1980-01-01

    Detached leaves and whole plants of sunflower were supplied with butyl 2-hydroxy-3-butynoate (BHB), a competitive inactivator of glycolate oxidase, to evaluate the possibility of inhibiting photorespiration and increasing photosynthetic efficiency. In all treatments in vivo and in vitro, BHB inhibited glycolate oxidase. With partially purified glycolate oxidase from spinach leaves, the apparent Ki for BHB was 13.2 micromolar. Low concentrations of BHB neither decreased photorespiration nor increased net photosynthesis. At higher concentrations, either a proportional decrease in photosynthesis and photorespiration or an inhibition of net photosynthesis greater than photorespiration was observed. CO2 evolution in BHB-treated leaves was O2-sensitive and was derived from recent photosynthate. BHB inhibited photosynthesis in 2, 21, or 50% O2 but the ratio of the rates of photosynthesis in these O2 concentrations was the same as in control leaves. BHB treatment resulted in a stimulation of dark respiration. As photosynthesis, photorespiration, and dark respiration were all affected by BHB, the action of BHB on whole leaf metabolism appears to be complex. Substantial inhibition of photorespiration was accompanied by inhibition of photosynthesis and increases in photosynthesis were not observed. PMID:16661492

  20. Habitat Complexity of Stream Leaf Packs: Effects on Benthic Macroinvertebrates and Leaf Litter Breakdown

    NASA Astrophysics Data System (ADS)

    Ruetz, C. R.; Vanhaitsma, D. L.; Breen, M. J.

    2005-05-01

    We investigated two attributes of leaf-pack complexity (i.e., leaf-pack mass and leaf surface area) on fish predation, colonization of benthic macroinvertebrates, and leaf breakdown rates in a coldwater Michigan stream. We manipulated three factors using a factorial design: fish (exclusion or control cage), leaf-pack mass (1, 3, or 5 g dry mass), and leaf surface area (<7, 7-10, or >10 cm leaf width). Acer leaves were fastened into leaf packs. Exclusion cages had mesh on all sides; control cages lacked mesh on two sides to provide access to fishes. Two replicate leaf packs were randomly collected after 25-31 d from two sections of the stream (n = 4). Common shredders were Gammarus, Pycnopsyche, and Lepidostoma. We did not detect a significant effect of fish predation on benthic macroinvertebrates or leaf breakdown (i.e., mass loss). Colonization of benthic macroinvertebrates appeared proportional to leaf-pack mass but was unaffected by the surface area of leaves. Leaf breakdown was more rapid among leaf packs with fewer leaves (i.e., leaves with large surface area and leaf packs with low mass) and greater numbers of shredders. We suspect that physical fragmentation is the primary mechanism for higher breakdown rates among leaf packs with fewer leaves.