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1

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

2

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

NASA Technical Reports Server (NTRS)

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.

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

1998-01-01

3

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

PubMed

Prior data indicated that enhanced availability of sucrose, a major product of photosynthesis in source leaves and the carbon source for secondary wall cellulose synthesis in fiber sinks, might improve fiber quality under abiotic stress conditions. To test this hypothesis, a family of transgenic cotton plants (Gossypium hirsutum cv. Coker 312 elite) was produced that over-expressed spinach sucrose-phosphate synthase (SPS) because of its role in regulation of sucrose synthesis in photosynthetic and heterotrophic tissues. A family of 12 independent transgenic lines was characterized in terms of foreign gene insertion, expression of spinach SPS, production of spinach SPS protein, and development of enhanced extractable V (max) SPS activity in leaf and fiber. Lines with the highest V (max) SPS activity were further characterized in terms of carbon partitioning and fiber quality compared to wild-type and transgenic null controls. Leaves of transgenic SPS over-expressing lines showed higher sucrose:starch ratio and partitioning of (14)C to sucrose in preference to starch. In two growth chamber experiments with cool nights, ambient CO(2) concentration, and limited light below the canopy, the transgenic line with the highest SPS activity in leaf and fiber had higher fiber micronaire and maturity ratio associated with greater thickness of the cellulosic secondary wall. PMID:17287885

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

2007-04-01

4

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

E-print Network

. Singh Department of Crop Science and Department of Plant Biology, North Carolina State University International Textile Center, Texas Tech University, Lubbock, TX 79409, USA G. M. Jividen Cotton Incorporated Issue Research Unit, USDA-ARS, 1604 E. FM 1294, Lubbock, TX 79403, USA W. X. Cai Á M. Hozain Á R. E

Strauss, Richard E.

5

Compartmentation studies on spinach leaf peroxisomes  

Microsoft Academic Search

The synthesis of glycerate by isolated intact spinach (Spinacia oleracea L.) leaf peroxisomes upon the addition of glycolate, serine, and glutamate, with either NADH or malate as reductant, has been measured. Measurement of the concentration dependence of NADH-and malate-dependent glycerate synthesis, and the exclusion of various artefacts, clearly demonstrate that under in vivo conditions the transfer of reducing equivalents into

Sigrun Reumann; Ralf Heupel; Hans W. Heldt

1994-01-01

6

Sucrose phosphate synthase activity and the co-ordination of carbon partitioning during sucrose and amino acid accumulation in desiccation-tolerant leaf material of the C4 resurrection plant Sporobolus stapfianus during dehydration  

Microsoft Academic Search

Both sucrose and amino acids accumulate in desicca- tion-tolerant leaf material of the C4 resurrection plant, Sporobolus stapfianus Gandoger (Poaceae). The pres- ent investigation was aimed at examining sucrose phosphate synthase (SPS) activity and various meta- bolic checkpoints involved in the co-ordination of carbon partitioning between these competing pathways during dehydration. In the initial phase of dehydration, photosynthesis and starch

Anne Whittaker; Tommaso Martinelli; Jill M. Farrant; Adriana Bochicchio; Concetta Vazzana

2007-01-01

7

Interaction between Silver Nanoparticles and Spinach Leaf  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

8

Critical nitrate levels for leaf lettuce, radish, and spinach plants  

Microsoft Academic Search

Leaf lettuce (Lactuca sativa var. crispa L.), radish (Raphanus sativus L.), and spinach (Spinacea oleracea L.) plants were grown in sand culture under variable N concentrations from 0.187 to 48.0 meq\\/l. The plants were harvested when those grown at 12 meq N\\/l had attained approximate market maturity. Growth was restricted, and symptoms of N deficiency were evident at the low

Donald N. Maynard; Allen V. Barker

1971-01-01

9

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

PubMed Central

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

Yelenosky, George; Guy, Charles L.

1989-01-01

10

ASimple Method forEstimating Intactness ofSpinach Leaf Protoplasts byGlycolate Oxidase Assay  

Microsoft Academic Search

ABSTRACr A method wasdeveloped forthequantitative analysis ofintactness of spinach leaf protoplasts using glycolate oxidase activity asanindex. Since glycolate doesnotpenetrate into protoplasts atneutral pH,the increase of02consumption bytheaddition ofglycolate toprotoplast suspension wasduetotheglycolate oxidase activity released fromdam- agedprotoplasts. Theproportion ofdamaged protoplasts inthewhole preparation wascalculated fromtheratio ofreleased andtotal glycolate oxidase activity. Freshly prepared spinach leaf protoplasts werefound to be80to90%intact asestimated bythemethod. Theeffect ofosmolarity ontherespiratory

ANDTAKASHI AKAZAWA

11

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

SciTech Connect

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.

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

1985-01-01

12

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...

13

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

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

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

2014-10-01

14

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

PubMed Central

1. ATP sulphurylase was purified up to 1000-fold from spinach leaf tissue. Activity was measured by sulphate-dependent [32P]PPiATP exchange. The enzyme was separated from Mg2+-requiring alkaline pyrophosphatase (which interferes with the PPiATP-exchange assay) and from other PPiATP-exchange activities. No ADP sulphurylase activity was detected. 2. Sulphate was the only form of inorganic sulphur that catalysed PPiATP exchange; Km (sulphate) was 3.1mm, Km (ATP) was 0.35mm and the pH optimum was 7.59.0. The enzyme was insensitive to thiol-group reagents and required either Mg2+ or Co2+ for activity. 3. The enzyme catalysed [32P]PPidATP exchange; Km (dATP) was 0.84mm and V (dATP) was 30% of V (ATP). Competition between ATP and dATP was demonstrated. 4. Selenate catalysed [32P]PPiATP exchange and competed with sulphate; Km (selenate) was 1.0mm and V (selenate) was 30% of V (sulphate). No AMP was formed with selenate as substrate. Molybdate did not catalyse PPiATP exchange, but AMP was formed. 5. Synthesis of adenosine 5?-[35S]sulphatophosphate was demonstrated by coupling purified ATP sulphurylase and Mg2+-dependent alkaline pyrophosphatase (also prepared from spinach) with [35S]sulphate and ATP as substrates; adenosine 5?-sulphatophosphate was not synthesized in the absence of pyrophosphatase. Some parameters of the coupled system are reported. PMID:5073745

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

1972-01-01

15

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

E-print Network

for their ability to inhibit or to enhance the growth of E. coli O157:H7 in vitro and on spinach leaf surfaces-inoculated with Erwinina perscinia and 20% cellobiose, a carbon source used by the phylloepiphytes but not E. coli O157:H7 of E. coli O157:H7 on edible plants. A total of 1512 phylloepiphytic bacterial isolates were screened

Falkinham, Joseph

16

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

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

17

NADH-Ferricyanide Reductase of Leaf Plasma Membranes : Partial Purification and Immunological Relation to Potato Tuber Microsomal NADH-Ferricyanide Reductase and Spinach Leaf NADH-Nitrate Reductase.  

PubMed

Plasma membranes obtained by two-phase partitioning of microsomal fractions from spinach (Spinacea oleracea L. cv Medania) and sugar beet leaves (Beta vulgaris L.) contained relatively high NADH-ferricyanide reductase and NADH-nitrate reductase (NR; EC 1.6.6.1) activities. Both of these activities were latent. To investigate whether these activities were due to the same enzyme, plasma membrane polypeptides were separated with SDS-PAGE and analyzed with immunoblotting methods. Antibodies raised against microsomal NADH-ferricyanide reductase (tentatively identified as NADH-cytochrome b(5) reductase, EC 1.6.2.2), purified from potato (Solanum tuberosum L. cv Bintje) tuber microsomes, displayed one single band at 43 kilodaltons when reacted with spinach plasma membranes, whereas lgG produced against NR from spinach leaves gave a major band at 110 kilodaltons together with a few fainter bands of lower molecular mass. Immunoblotting analysis using inside-out and right-side-out plasma membrane vesicles strongly indicated that NR was not an integral protein but probably trapped inside the plasma membrane vesicles during homogenization. Proteins from spinach plasma membranes were solubilized with the zwitterionic detergent 3-[(3-cholamidopropyl) dimethylammonio] 1-propane-sulfonate and separated on a Mono Q anion exchange column at pH 5.6 with fast protein liquid chromatography. One major peak of NADH-ferricyanide reductase activity was found after separation. The peak fraction was enriched about 70-fold in this activity compared to the plasma membrane. When the peak fractions were analyzed with SDS-PAGE the NADH-ferricyanide reductase activity strongly correlated with a 43 kilodalton polypeptide which reacted with the antibodies against potato microsomal NADH-ferricyanide reductase. Thus, our data indicate that most, if not all, of the truly membrane-bound NADH-ferricyanide reductase activity of leaf plasma membranes is due to an enzyme very similar to potato tuber microsomal NADH-ferricyanide reductase (NADH-cytochrome b(5) reductase). PMID:16667982

Askerlund, P; Laurent, P; Nakagawa, H; Kader, J C

1991-01-01

18

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...

19

Functional analysis of sucrose phosphate synthase (SPS) and sucrose synthase (SS) in sugarcane (Saccharum) cultivars.  

PubMed

Sucrose phosphate synthase (SPS; EC 2.4.1.14) and sucrose synthase (SS; EC 2.4.1.13) are key enzymes in the synthesis and breakdown of sucrose in sugarcane. The activities of internodal SPS and SS, as well as transcript expression were determined using semi-quantitative RT-PCR at different developmental stages of high and low sucrose accumulating sugarcane cultivars. SPS activity and transcript expression was higher in mature internodes compared with immature internodes in all the studied cultivars. However, high sugar cultivars showed increased transcript expression and enzyme activity of SPS compared to low sugar cultivars at all developmental stages. SS activity was higher in immature internodes than in mature internodes in all cultivars; SS transcript expression showed a similar pattern. Our studies demonstrate that SPS activity was positively correlated with sucrose and negatively correlated with hexose sugars. However, SS activity was negatively correlated with sucrose and positively correlated with hexose sugars. The present study opens the possibility for improvement of sugarcane cultivars by increasing expression of the respective enzymes using transgene technology. PMID:21309979

Verma, A K; Upadhyay, S K; Verma, P C; Solomon, S; Singh, S B

2011-03-01

20

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

PubMed

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

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

21

Testing Models of Fatty Acid Transfer and Lipid Synthesis in Spinach Leaf Using in Vivo Oxygen-18 Labeling1  

PubMed Central

Oxygen-18 labeling has been applied to the study of plant lipid biosynthesis for the first time. [13C218O2]Acetate was incubated with spinach (Spinacia oleracea) leaves and the 18O content in fatty acid methyl esters isolated from different lipid classes measured by gas chromatography-mass spectometry. Fatty acids isolated from lipids synthesized within the plastid, such as monogalactosyldiacylglycerol, show an 18O 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 18O 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 18O or, less likely, complete loss of 18O, but not a 50% loss of 18O. Thus, existing models for fatty acid transfer from the plastid and for spatially separate synthesis of prokaryotic and eukaryotic lipids have both been confirmed. PMID:10594108

Pollard, Mike; Ohlrogge, John

1999-01-01

22

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

PubMed

Oxygen-18 labeling has been applied to the study of plant lipid biosynthesis for the first time. [(13)C(2)(18)O(2)]Acetate was incubated with spinach (Spinacia oleracea) leaves and the (18)O content in fatty acid methyl esters isolated from different lipid classes measured by gas chromatography-mass spectometry. Fatty acids isolated from lipids synthesized within the plastid, such as monogalactosyldiacylglycerol, show an (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 (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 (18)O or, less likely, complete loss of (18)O, but not a 50% loss of (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. PMID:10594108

Pollard, M; Ohlrogge, J

1999-12-01

23

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

PubMed Central

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

Hashimoto, Haruki; Possingham, John Victor

1989-01-01

24

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 ...

25

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

SciTech Connect

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.

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

1989-04-01

26

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

SciTech Connect

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.

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

2008-01-01

27

Norovirus surrogate survival on spinach during preharvest growth.  

PubMed

Produce can become contaminated with human viral pathogens in the field through soil, feces, or water used for irrigation; through application of manure, biosolids, pesticides, and fertilizers; and through dust, insects, and animals. The objective of this study was to assess the survival and stability of human noroviruses and norovirus surrogates (Murine norovirus [MNV] and Tulane virus [TV]) on foliar surfaces of spinach plants in preharvest growth conditions. Spinach plants were housed in a biocontrol chamber at optimal conditions for up to 7 days and infectivity was determined by plaque assay. Virus inoculation location had the largest impact on virus survival as viruses present on adaxial leaf surfaces had lower decimal reduction time (D values) than viruses present on abaxial leaf surfaces. Under certain conditions, spinach type impacted virus survival, with greater D values observed from survival on semi-savoy spinach leaves. Additional UVA and UVB exposure to mimic sunlight affected virus survival on adaxial surfaces for both semi-savoy and smooth spinach plants for both viruses. Human GII norovirus inoculated onto semi-savoy spinach had an average D value that was not statistically significant from MNV and TV, suggesting that these surrogates may have similar survival on spinach leaves compared with human noroviruses. An understanding of the behavior of enteric viruses on spinach leaves can be used to enhance growers' guidelines and for risk assessment with certain growing conditions. PMID:23506365

Hirneisen, Kirsten A; Kniel, Kalmia E

2013-04-01

28

Sucrose phosphate phosphatase in the green alga Klebsormidium flaccidum (Streptophyta) lacks an extensive C-terminal domain and differs from that of land plants.  

PubMed

Previously, it was reported that like land plants, the green alga Klebsormidium flaccidum (Streptophyta) accumulates sucrose during cold acclimation (Nagao et al. Plant Cell Environ 31:872-885, 2008), suggesting that synthesis of sucrose could enhance the freezing tolerance of this alga. Because sucrose phosphate phosphatase (SPP; EC 3.1.3.24) is a key enzyme in the sucrose synthesis pathway in plants, we analyzed the SPP gene in K. flaccidum (KfSPP, GenBank accession number AB669024) to clarify its role in sucrose accumulation. As determined from its deduced amino acid sequence, KfSPP contains the N-terminal domain that is characteristic of the L-2-haloacid-dehalogenase family of phosphatases/hydrolases (the HAD phosphatase domain). However, it lacks the extensive C-terminal domain found in SPPs of land plants. Database searches revealed that the SPPs in cyanobacteria also lack the C-terminal domain. In addition, the green alga Coccomyxa (Chlorophyta) and K. flaccidum, which are closely related to land plants, have cyanobacterial-type SPPs, while Chlorella (Chlorophyta) has a land plant-type SPP. These results demonstrate that even K. flaccidum (Streptophyta), as a recent ancestor of land plants, has the cyanobacterial-type SPP lacking the C-terminal domain. Because SPP and sucrose phosphate synthase (SPS) catalyze sequential reactions in sucrose synthesis in green plant cells and the lack of the C-terminal domain in KfSPP is predicted to decrease its activity, the interaction between decreased KfSPP activity and SPS activity may alter sucrose synthesis during cold acclimation in K. flaccidum. PMID:22095241

Nagao, Manabu; Uemura, Matsuo

2012-04-01

29

Texas Crop Profile: Spinach  

E-print Network

into well-drained loamy soils fer- tilized at a rate of approximately 120 pounds of nitrogen, 75 pounds phosphorus and 80 pounds potassium (N-P-K) per acre. Seeding is at 5 to 10 pounds per acre, spaced three to six plants per foot of row. About 70 percent...- year period, approximately 80 percent of Texas spinach acreage will have aphid problems. Pest life cycles: Aphids can overwinter in the egg stage, but adults often are a season long spinach problem. Aphids began life either by hatching from an egg...

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

2000-04-12

30

Nitrogen Uptake in Spinach  

NASA Astrophysics Data System (ADS)

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.

Ramirez, J.; VanBenthem, P.

2013-12-01

31

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

PubMed

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

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

2012-01-01

32

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

PubMed Central

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

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

2012-01-01

33

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...

34

Biogenic synthesis of calcium oxalate crystal by reaction of calcium ions with spinach lixivium.  

PubMed

In this paper, we report a biogenic synthesis protocol for preparation of calcium oxalate (CaC2O4, CaOx) crystal at room temperature by a simple protein-mediated reaction of aqueous Ca2+ ions with the C2O4(2-) ions spontaneously released from spinach. The aggregation of calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) with a rod-like morphology was mainly formed in the spinach root lixivium, and the proportion of COM crystal in the aggregation increased with the concentration of Ca2+ ions increasing, however, spindle-shaped crystal was mainly obtained in the spinach leaf lixivium and the content of COM in the product was higher than that obtained in the root lixivium with the similar concentration of Ca2+ ions. COM phase disappeared and only COD crystal with morphology of tetragonal bipyramidal prisms presented in the product when the leaf lixivium was replaced by the leaf broth. The biomolecules such as proteins with molecular weight of 31kDa liberated from the spinach root are negative-charged, which played important roles for the control of CaOx crystal growth in the root lixivium corresponding to the changes of protein secondary structures after reaction with Ca2+ ions. This research was potentially important for unraveling the biomineralization mechanism of CaOx crystal. PMID:20399625

Li, Shi-Kuo; Xie, An-Jian; Shen, Yu-Hua; Yu, Xue-Rong; Hu, Gang

2010-07-01

35

2012 International Spinach Conference San Antonio, TX  

E-print Network

2012 International Spinach Conference San Antonio, TX 29-30 November 2012 " Tentative ProgramLife Extension Service, San Antonio, TX. Stein, Larry. "Growing fresh market and processing spinach in Texas Antonio, TX. Valdez, Marcel. "Strategies for implementing a food safety program on the farm." Zavala

Mukhtar, Saqib

36

Spinach and Mushroom Enchilada Lasagna Ingredients  

E-print Network

Spinach and Mushroom Enchilada Lasagna Ingredients: 2 teaspoons olive oil 1 onion 2 cloves garlic 3 Jack cheese, shredded Directions 1. Preheat the oven to 350F. Heat oil in a large non-stick skillet. 2 vegetables are cooking, squeeze water out of spinach. Add mushrooms to skillet and cook about 15 to 20

Liskiewicz, Maciej

37

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

38

Induction of Hexose-Phosphate Translocator Activity in Spinach Chloroplasts.  

PubMed Central

Many environmental and experimental conditions lead to accumulation of carbohydrates in photosynthetic tissues. This situation is typically associated with major changes in the mRNA and protein complement of the cell, including metabolic repression of photosynthetic gene expression, which can be induced by feeding carbohydrates directly to leaves. In this study we examined the carbohydrate transport properties of chloroplasts isolated from spinach (Spinacia oleracea L.) leaves fed with glucose for several days. These chloroplasts contain large quantities of starch, can perform photosynthetic 3-phosphoglycerate reduction, and surprisingly also have the ability to perform starch synthesis from exogenous glucose-6-phosphate (Glc-6-P) both in the light and in darkness, similarly to heterotrophic plastids. Glucose-1-phosphate does not act as an exogenous precursor for starch synthesis. Light, ATP, and 3-phosphoglyceric acid stimulate Glc-6-P-dependent starch synthesis. Short-term uptake experiments indicate that a novel Glc-6-P-translocator capacity is present in the envelope membrane, exhibiting an apparent Km of 0.54 mM and a Vmax of 2.9 [mu]mol Glc-6-P mg-1 chlorophyll h-1. Similar results were obtained with chloroplasts isolated from glucose-fed potato leaves and from water-stressed spinach leaves. The generally held view that sugar phosphates transported by chloroplasts are confined to triose phosphates is not supported by these results. A physiological role for a Glc-6-P translocator in green plastids is presented with reference to the source/sink function of the leaf. PMID:12228584

Quick, W. P.; Scheibe, R.; Neuhaus, H. E.

1995-01-01

39

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...

40

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...

41

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

NASA Astrophysics Data System (ADS)

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.

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

2011-06-01

42

Computational analysis of fluorescence induction curves in intact spinach leaves treated at different pH.  

PubMed

Effects of change in pH have been investigated on spinach leaf discs by measuring fluorescence induction kinetics using plant efficiency analyzer (PEA). On the basis of computational analysis of the results, we have reported that acidic pH causes a significant inhibition of the donor and the acceptor side of PS II. Energy flux models have been presented using the software Biolyzer HP 3. Effects of pH were investigated on the antenna size heterogeneity of PS II and a relative change in the proportions of ?, ?, and ? centers was observed. PMID:20705115

Tongra, Teena; Mehta, Pooja; Mathur, Sonal; Agrawal, Divya; Bharti, Sudhakar; Los, Dmitry A; Allakhverdiev, Suleyman I; Jajoo, Anjana

2011-02-01

43

A Spinach molecular beacon triggered by strand displacement.  

PubMed

We have re-engineered the fluorescent RNA aptamer Spinach to be activated in a sequence-dependent manner. The original Spinach aptamer was extended at its 5'- and 3'-ends to create Spinach.ST, which is predicted to fold into an inactive conformation and thus prevent association with the small molecule fluorophore DFHBI. Hybridization of a specific trigger oligonucleotide to a designed toehold leads to toehold-initiated strand displacement and refolds Spinach into the active, fluorophore-binding conformation. Spinach.ST not only specifically detects its target oligonucleotide but can discriminate readily against single-nucleotide mismatches. RNA amplicons produced during nucleic acid sequence-based amplification (NASBA) of DNA or RNA targets could be specifically detected and reported in real-time by conformational activation of Spinach.ST generated by in vitro transcription. In order to adapt any target sequence to detection by a Spinach reporter we used a primer design technique that brings together otherwise distal toehold sequences via hairpin formation. The same techniques could potentially be used to adapt common Spinach reporters to non-nucleic acid analytes, rather than by making fusions between aptamers and Spinach. PMID:24942625

Bhadra, Sanchita; Ellington, Andrew D

2014-08-01

44

Detection and quantification of Verticillium dahliae in spinach seed  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

45

Spinach as a source of carotenoids, folate and antioxidant activity  

Microsoft Academic Search

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

J. J. M. Castenmiller

2000-01-01

46

Pathway for the Synthesis of Triacylglycerols from Monogalactosyldiacylglycerols in Ozone-Fumigated Spinach Leaves  

PubMed Central

When the upper leaf surface of spinach (Spinacia oleracea L.) plants was treated with [1-14C]acetate and grown for 2 days, 14C 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 14C among lipid classes, i.e. a marked increase of 14C content in triacylglycerol (TG) and 1,2-diacylglycerol (1,2-DG) and a decrease of label in monogalactosyldiacylglycerol (MGDG) without affecting 14C 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 ozonetreated 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 [1-14C]linolenic acid in leaf discs excised from ozone-fumigated leaves; 14C was effectively incorporated into TG but not into 1,2-DG. These results demonstrate the synthesis of TG from 1,2-DG and FFA which were liberated from MGDG in ozone-fumigated spinach leaves. Images Figure 3 PMID:16667778

Sakaki, Takeshi; Kondo, Noriaki; Yamada, Mitsuhiro

1990-01-01

47

Interactive electron micrograph--leaf cell  

NSDL National Science Digital Library

The following learning object is an electron micrograph of a spinach leaf cell. It is displayed through Flash and uses Zoomify to simulate a virtual microscope. Some of the organelles have been colored for identification purposes. The accompanying interactive QuickTime using a color legend to display the name of each organelle and to provide additional information, including a higher magnification of the organelle.

PhD Betty L Black (NC State University Biology)

2008-09-15

48

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

PubMed

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

Furukawa, Yuichiro; Hasegawa, Hiroshi

2006-01-01

49

Prenyl lipid formation in spinach chloroplasts and in a cell-free system of Synechococcus (Cyanobacteria): polyprenols, chlorophylls, and fatty acid prenyl esters  

Microsoft Academic Search

Isolated chloroplasts from spinach leaf cells, chloroplast subfractions, and a cell-free system of the cyanobacterium Synechococcus CCAP 6312 incorporated [1-14C]isopentenyl pyrophosphate in high yields into prenyl lipids. Products were polyprenols (C20, C45) chlorophylls, quinoid compounds, and fatty acid prenyl esters; prenyl pyrophosphates occurred in trace amounts, and carotenes were only formed to a limited extent in the Synechococcus system. The

F. Lfitke-Brinkhaus; G. Weiss; H. Kleinig

1985-01-01

50

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

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

Kovtun, Y.; Daie, J.

1995-01-01

51

Growth Conditions To Reduce Oxalic Acid Content of Spinach  

NASA Technical Reports Server (NTRS)

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.

Johnson-Rutzke, Corinne

2003-01-01

52

Thermal inactivation kinetics of hepatitis A virus in spinach.  

PubMed

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

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

2015-01-16

53

Chloroplast Growth and Replication in Germinating Spinach Cotyledons following Massive ?-Irradiation of the Seed  

PubMed Central

Spinach seeds (Spinacia oleracea L.) given massive doses of ?-irradiation (500 krad) germinate and form a seedling with two green cotyledons and a radicle, but develop no further. Irradiated cotyledons show no increase in cell number or total DNA over a 7-day period in the light, while in control cotyledons there is a small increase in cell number and large increases in total DNA and chloroplast number. The chloroplasts of irradiated cotyledons are delayed in their division, become greatly enlarged and contain large amounts of starch. The whole population of chloroplasts subsequently undergoes a wave of division. The daughter chloroplasts show normal thylakoid development, but have some abnormal structural features caused by the radiation stress. Information on the effect of X-irradiation, ultraviolet irradiation, and 5-fluorodeoxyuridine on chloroplast replication and on chloroplast and nuclear DNA synthesis was obtained from cultured spinach leaf discs. It appears that chloroplast replication is more resistant to ionizing radiation than cell division and can proceed in the absence of nuclear DNA synthesis and greatly reduced chloroplast DNA synthesis. Images PMID:16659421

Rose, Ray; Possingham, John

1976-01-01

54

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

PubMed

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

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

2014-03-01

55

Identification of Six Endogenous Gibberellins in Spinach Shoots 1  

PubMed Central

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

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

1980-01-01

56

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

PubMed Central

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

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

1994-01-01

57

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...

58

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...

59

Rapid isolation of intact chloroplasts from spinach leaves.  

PubMed

In this chapter, a rapid method to isolate intact chloroplasts from spinach leaves is described. Intact chloroplasts are isolated using two short centrifugation steps and avoiding the use of percoll gradient. Intactness of chloroplast is evaluated by the inability of potassium ferricyanide to enter inside the chloroplasts and to act as an electron acceptor for photosystem II. PMID:20960139

Joly, David; Carpentier, Robert

2011-01-01

60

Expression and purification of spinach nitrite reductase in E. coli  

SciTech Connect

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.

Bellissimo, D.; Privalle, L. (Ciba-Giegy Corp., Research Triangle Park, NC (United States))

1991-03-11

61

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

62

Leaf Shape  

NSDL National Science Digital Library

This illustrated guide is designed to help students recognize and learn the different types of leaf shapes. The single Web page, which can be easily printed for use at field sites, shows five leaf shapes.

63

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

PubMed Central

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

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

1988-01-01

64

Photosynthate partitioning during flowering in relation to senescence of spinach  

SciTech Connect

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.

Sklensky, D.; Davies, P.J. (Cornell Univ., Ithaca, NY (USA))

1990-05-01

65

Leaf Margins  

NSDL National Science Digital Library

This illustrated guide is designed to help students recognize and learn the difference between entire and toothed leaf margins. The single Web page can be easily printed for use at field sites. Both leaf margin illustrations identify the leaf blade and the petiole.

66

Microbiological Quality of Bagged Cut Spinach and Lettuce Mixes  

Microsoft Academic Search

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. Increases in

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

2008-01-01

67

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

68

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

PubMed Central

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

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

1983-01-01

69

Localization, Purification, and Characterization of Shikimate Oxidoreductase-Dehydroquinate Hydrolyase from Stroma of Spinach Chloroplasts 1  

PubMed Central

The stroma of chloroplasts is probably the sole site of the shikimate pathway enzymes shikimate oxidoreductase/dehydroquinate hydrolyase (SORase/DHQase) in spinach leaves. (a) The chromatographic behavior of the bifunctional protein SORase/DHQase on several separation materials with extracts from stroma compared with leaf extracts showed only one peak of enzymic activity originating from the stroma. (b) Polyacrylamide gel electrophoresis (PAGE) of these extracts followed by specific staining resulted in the same pattern without a band of extraplastidic enzyme. (c) In protoplast fractionation experiments it was shown that SORase/DHQase was present only in the soluble chloroplast protein fraction. An improved purification procedure for SORase/DHQase from stroma of chloroplasts, yield 40%, 1600 times as pure, gave essentially one protein band on sodium dodecyl sulfate-PAGE. Our results demonstrate that both enzyme functions are carried out by a single polypeptide. Nondenaturing PAGE exhibited a pattern of four bands with SORase/DHQase showing that they differ in charge but not in their molecular weight. Molecular weight was determined to be 67 kilodaltons (gel filtration) and 59 kilodaltons (PAGE) for all four forms. It was proven they were not due to artifacts. The four forms show similar kinetic properties, their Km and pH optima differing only very slightly. Response to some metabolites is reported. Images Fig. 3 Fig. 7 PMID:16664373

Fiedler, Erich; Schultz, Gernot

1985-01-01

70

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 ...

71

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 ...

72

A Simplified Method for the Microscale Extraction of Pigments from Spinach  

NASA Astrophysics Data System (ADS)

A method is presented for microscale sample preparation for the thin-layer chromatographic analysis of the pigments in spinach. A commercial vegetable juicer is used for the initial extraction from spinach. This is followed by filtration, liquid/liquid extraction, centrifugation, and evaporation. The new sample preparation technique is significantly more efficient than present methods and minimizes solvents used for extraction.

Cousins, Kimberley R.; Pierson, Kathleen M.

1998-10-01

73

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...

74

Localization of phosphatidylcholine in outer envelope membrane of spinach chloroplasts  

PubMed Central

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

1985-01-01

75

Studies of a New Fusarium Wilt of Spinach in Texas.  

E-print Network

by the onion maggot. With the latter, however, the chief injury is in the center of the plant though the outside leaves turn yellow and may even wilt. By cutting into such affected plants, one or more maggots may be found in the rotted center. Not infre...- quently the maggot injury opens the way to infection by Fusarium milt. In Texas, spinach is also found to be attacked by a Rhizoctonia, which causes numerous deep, dark lesions on the roots, and this results In 2t stunting of the plant. Like maggot...

Taubenhaus, J. J. (Jacob Joseph)

1926-01-01

76

Alleviation of cadmium phytotoxicity by magnesium in Japanese mustard spinach  

Microsoft Academic Search

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

M. D. Abul KASHEM; Shigenao Kawai

2007-01-01

77

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

PubMed

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

Brogren, Madelene; Savage, Geoffrey P

2003-01-01

78

Leaf Activities.  

ERIC Educational Resources Information Center

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

Mingie, Walter

79

Insect molting hormone and sterol biosynthesis in spinach  

SciTech Connect

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.

Grebenok, R.J.; Adler, J.H. (Michigan Technological Univ., Houghton (USA))

1990-05-01

80

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

SciTech Connect

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.

Sakaki, Takeshi; Kondo, Noriaki; Yamada, Mitsuhiro (National Institute for Environmental Studies, Ibaraki (Japan) Univ. of Tokyo (Japan))

1990-10-01

81

Simultaneous measurement of changes in red and blue fluorescence in illuminated isolated chloroplasts and leaf pieces: The contribution of NADPH to the blue fluorescence signal  

Microsoft Academic Search

A newly developed nitrogen laser fluorimeter insensitive to actinic illumination was used to follow simultaneously the light induced changes in red and blue fluorescence of intact isolated spinach chloroplasts and leaf pieces. The recorded variable blue fluorescence was linked to a water soluble component of intact isolated chloroplasts, depended on Photosystem I, and was related to changes in carbon metabolism.

Zoran G. Cerovic; Maurice Bergher; Yves Goulas; Stephane Tosti; Ismael Moya

1993-01-01

82

Leaf Identification  

NSDL National Science Digital Library

This straightforward tutorial on leaf identification comes from the Department of Horticulture at Penn State University. Simple diagrams, helpful photos, and clear explanations make short work of learning the basics of leaf identification. The website even includes a section on why anyone should bother learning this skill (i.e. it's not just for dedicated horticulturists and botanists). The tutorial covers leaf structure, blade shape, margins, venation, and so on. The self-testing component appears to be unavailable at this time, but this site as a whole is definitely worth a look.

2008-09-12

83

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...

84

Leaf Arrangement  

NSDL National Science Digital Library

This illustrated guide to leaf arrangement shows students how leaves attached at a stem node can be in alternate, opposite, or whorled arrangements. This single Web page can be easily printed for use at field sites.

85

Effect of ?-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)

In the present study we have synthesized chitosan from waste prawn shell via ?-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 ?-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 1.9105 to 6.5104 Da and thus increased its solubility in water. Nonirradiated and ?-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.

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

2013-01-01

86

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

PubMed Central

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

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

87

Comparison of acetate- and pyruvate-dependent fatty-acid synthesis by spinach chloroplasts  

Microsoft Academic Search

In recent studies using intact chloroplasts of spinach (Spinacia oleracea L.) to investigate the accumulation of acetyl-CoA produced by the activity of either acetyl-CoA synthetase (EC 6.2.1.1) or the pyruvate-dehydrogenase complex, this product was not detectable. These results in combination with new information on the physiological levels of acetate and pyruvate in spinach chloroplasts (H.-J. Treede et al. 1986, Z.

Jutta Springer; Klaus-Peter Heise

1989-01-01

88

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

Microsoft Academic Search

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

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

2002-01-01

89

Leaf Development  

PubMed Central

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

2013-01-01

90

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

NASA Technical Reports Server (NTRS)

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.

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

91

Leaf Living  

NSDL National Science Digital Library

In this outdoor fall activity, learners find out what living in or under a layer of leaves is like. Learners will discover that animals that live in leaf litter use different senses to find prey, avoid predators, and to navigate through the litter. Learners role play predator and preythe "prey" hides in a large pile of leaves, and the "predator" tries to "strike" by reaching straight into the leaf pile to grab the "prey." Learners also consider what body adaptations help organisms that spend part of their life under the leaves.

Lawrence Hall of Science

1981-01-01

92

Leaf Type  

NSDL National Science Digital Library

This illustrated guide to leaf types is designed to help students understand the differences between compound and simple leaves. This single Web page can be easily printed for use at field sites. Along with an explanation of both types, the guide includes a short description of related terms.

93

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 ...

94

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

PubMed

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

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

2014-08-01

95

Uptake of l-Ascorbate by Intact Spinach Chloroplasts  

PubMed Central

Uptake of l-[1-14C]ascorbate by intact ascorbate-free spinach (Spinacia oleracea L. cv Vitalr) chloroplasts has been investigated using the technique of silicone oil filtering. Rates greater than 100 micromoles per milligram chlorophyll per hour (external concentration, 10 millimolar) of ascorbate transport were observed. Ascorbate uptake into the sorbitol-impermeable space (stroma) followed the Michaelis-Menten-type characteristic for substrate saturation. A Km of 18 to 40 millimolar was determined. Transport of ascorbate across the chloroplast envelope resulted in an equilibrium of the ascorbate concentrations between stroma and medium. A pH optimum of 7.0 to 7.5 and the lack of alkalization of the medium upon ascorbate uptake suggest that only the monovalent ascorbate anion is able to cross the chloroplast envelope. The activation energy of ascorbate uptake was determined to be 65.8 kilojoules (16 kilocalories) per mole (8 to 20C). Interference of ascorbate transport with substrates of the phosphate or dicarboxylate translocator could not be detected, but didehydroascorbate was a competitive inhibitor. Preloading of chloroplasts with didehydroascorbate resulted in an increase of Vmax but did not change the Km for ascorbate. Millimolar concentrations of the sulfhydryl reagent p-chloromercuriphenyl sulfonate inhibited ascorbate uptake. The data are interpreted in terms of ascorbate uptake into chloroplasts by the mechanism of facilitated diffusion mediated by a specific translocator. PMID:16663182

Beck, Erwin; Burkert, Anette; Hofmann, Margit

1983-01-01

96

Synthesis of Mono- and Digalactosyldiacylglycerol in Isolated Spinach Chloroplasts 1  

PubMed Central

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

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

1988-01-01

97

DNA Content of Beta vulgaris Chloroplasts during Leaf Cell Expansion.  

PubMed

During the growth of beet leaves from 2 to 3 to 25 to 30 centimeters, the leaf cells increase in size, the average number of chloroplasts per cell increases from 11 to 65 and the amount of chloroplast DNA per cell increases from 1100 to 1900 plastome copies. The average number of copies of the plastome per chloroplast decreases from 104 in 2 to 3-centimeter leaves to 29 in 25 to 30-centimeter leaves during a period when the chloroplasts undergo two to three rounds of division and increase diameter from 1.5 to 4.9 micrometers. This result is at variance with previously published studies of beet chloroplasts but agrees with the conclusions reached in more recent studies of pea and spinach and wheat leaf cell expansion. PMID:16662908

Tymms, M J; Scott, N S; Possingham, J V

1983-04-01

98

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...

99

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...

100

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...

101

Fluorescent monitoring of RNA assembly and processing using the split-spinach aptamer.  

PubMed

As insights into RNA's many diverse cellular roles continue to be gained, interest and applications in RNA self-assembly and dynamics remain at the forefront of structural biology. The bifurcation of functional molecules into nonfunctional fragments provides a useful strategy for controlling and monitoring cellular RNA processes and functionalities. Herein we present the bifurcation of the preexisting Spinach aptamer and demonstrate its utility as a novel split aptamer system for monitoring RNA self-assembly as well as the processing of pre-short interfering substrates. We show for the first time that the Spinach aptamer can be divided into two nonfunctional halves that, once assembled, restore the original fluorescent signal characteristic of the unabridged aptamer. In this regard, the split-Spinach aptamer is represented as a potential tool for monitoring the self-assembly of artificial and/or natural RNAs. PMID:24932527

Rogers, Tucker A; Andrews, Grant E; Jaeger, Luc; Grabow, Wade W

2015-02-20

102

Hydrogen Peroxide Synthesis in Isolated Spinach Chloroplast Lamellae 1  

PubMed Central

Light-dependent O2 reduction concomitant with O2 evolution, ATP formation, and NADP reduction were determined in isolated spinach (Spinacia oleracea L. var. America) chloroplast lamellae fortified with NADP and ferredoxin. These reactions were investigated in the presence or absence of catalase, providing a tool to estimate the reduction of O2 to H2O2 (Mehler reaction) concomitant with NADP reduction. In the presence of 250 micromolar O2, O2 photoreduction, simultaneous with NADP photoreduction, was dependent upon light intensity, ferredoxin, Mn2+, NADP, and the extent of coupling of phosphorylation to electron flow. In the presence of an uncoupling concentration of NH4+, saturating light intensity (>500 watts/square meter), saturating ferredoxin (10 micromolarity) rate-limiting to saturating NADP (0.2-0.9 millimolarity), and Mn2+ (50-1000 micromolarity), the maxium rates of O2 reduction were 13-25 micromoles/milligram chlorophyll per hour, while concomitant rates of O2 evolution and NADP reduction were 69 to 96 and 134 to 192 micromoles/milligram chlorophyll per hour, respectively. Catalase did not affect the rate of NADPH or ATP formation but decreased the NADPH:O2 ratios from 2.3-2.8 to 1.9-2.1 in the presence of rate-limiting as well as saturating concentrations of NADP. Photosynthetic electron flow at a rate of 31 micromoles O2 evolved/milligram chlorophyll per hour was coupled to the synthesis of 91 micromoles ATP/milligram chlorophyll per hour, while the concomitant rate of O2 reduction was 0.6 micromoles/milligram chlorophyll per hour and was calculated to be associated with an apparent ATP formation of only 2 micromoles/milligram chlorophyll per hour. Thus, electron flow from H2O to O2 did not result in ATP formation significantly above that produced during NADP reduction. PMID:16662662

Robinson, J. Michael; Gibbs, Martin

1982-01-01

103

Coliforms and prevalence of Escherichia coli and foodborne pathogens on minimally processed spinach in two packing plants.  

PubMed

Minimally processed spinach has been recently associated with outbreaks of foodborne illnesses. This study investigated the effect of commercial minimal processing of spinach on the coliform and Escherichia coli counts and the prevalence of E. coli O157:H7, Salmonella, Shigella spp., and Listeria monocytogenes on two types of spinach before and after minimal processing. A total of 1,356 spinach samples (baby spinach, n = 574; savoy spinach, n = 782) were collected daily in two processing plants over a period of 14 months. Raw spinach originated from nine farms in the United States and three farms in Canada. Overall, the proportion of samples positive for coliforms increased from 53% before minimal processing to 79% after minimal processing (P < 0.001). Average total coliform counts also increased significantly after processing, especially in baby spinach (mean +/- standard deviation, 1.16 +/- 0.14 log CFU/g to 2.37 +/- 0.08 log CFU/g following processing; P < 0.001). E. coli was isolated from 8.9% of the samples (mean +/- standard deviation, 1.81 +/- 0.14 log CFU/g), and no difference in prevalence or CFU counts after processing (P > 0.1) was observed. E. coli O157:H7 and Shigella spp. were not isolated from any of the samples. Salmonella and L. monocytogenes were isolated from 0.4 and 0.7% of samples, respectively. Results demonstrate that commercial minimal processing of spinach based on monitored chlorine washing and drying may not decrease microbial load on spinach leaves as expected. Further research is needed to identify the most appropriate measures to control food safety risk under commercial minimal processing of fresh vegetables. PMID:19244890

Ilic, Sanja; Odomeru, Joseph; LeJeune, Jeffrey T

2008-12-01

104

Tree Leaf Identification and Leaf Display Activity  

NSDL National Science Digital Library

This activity is a tree leaf collection, identification, and display of dried and pressed leaves. It teaches students about distinguishing leaf characteristics as well as a way to display and label their collection.

Rebecca Hansing

105

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

Microsoft Academic Search

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

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

2008-01-01

106

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...

107

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...

108

Using Spinach aptamer to correlate mRNA and protein levels in Escherichia coli.  

PubMed

In vivo gene expression measurements have traditionally relied on fluorescent proteins such as green fluorescent protein (GFP) with the help of high-sensitivity equipment such as flow cytometers. However, fluorescent proteins report only on the protein level inside the cell without giving direct information about messenger RNA (mRNA) production. In 2011, an aptamer termed Spinach was presented that acts as an RNA mimic of GFP when produced in Escherichia coli and mammalian cells. It was later shown that coexpression of a red fluorescent protein (mRFP1) and the Spinach aptamer, when included into the same gene expression cassette, could be utilized for parallel in vivo measurements of mRNA and protein production. As accurate characterization of component biological parts is becoming increasingly important for fields such as synthetic biology, Spinach in combination with mRFP1 provide a great tool for the characterization of promoters and ribosome binding sites. In this chapter, we discuss how live-cell imaging and flow cytometry can be used to detect and measure fluorescence produced in E. coli cells by different constructs that contain the Spinach aptamer and the mRFP1 gene. PMID:25605386

Pothoulakis, Georgios; Ellis, Tom

2015-01-01

109

FTIR spectroscopy shows structural similarities between photosystems II from cyanobacteria and spinach  

E-print Network

FTIR spectroscopy shows structural similarities between photosystems II from cyanobacteria resolution. Therefore Fourier transform infrared (FTIR) difference spectroscopy was used to compare PSII from-enriched membranes from spinach (BBY). FTIR difference spectra of T. elonga- tus core complexes are presented

Roegner, Matthias

110

Original article Uptake of Cd and Ni by spinach, Spinacea oleracea (L.)  

E-print Network

of Egypt. Microplots were irrigated either with water or with salt solution (0.8 gL-1) for 9 weeks, the scarcity of high quality irrigation water and increasing heavy metal pollution of soils and waters [13Original article Uptake of Cd and Ni by spinach, Spinacea oleracea (L.) from polluted soil under

Paris-Sud XI, Universit de

111

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...

112

Simple and Quick: Tilapia and Spinach Parchment Packet Also known as Tilapia En Papillote  

E-print Network

olive oil 1/4 tsp salt 1/8 tsp pepper lemon slice two or three slices, use juice of remaining piece of lemon Place 1 cup spinach in center of parchment paper. Top with cup chopped of fish with 1 tsp of olive oil. Scatter garlic over the top. Drizzle a small amount of fresh lemon

Jawitz, James W.

113

Fitting a Nonlinear Regression Model to Gauge Heavy Metal Uptake in Spinach (Amaranthus hybridus L.)  

Microsoft Academic Search

The main focus of the study was to model and analyze the data on the uptake of heavy metals specifically iron in spinach (Amaranthus hybridus L). The most common empirical model used is the simple regression but it was found that this model was not adequate based on the relationship and the value of R2. By examining the plot of

R. Ahmad-Mahir; W. D. Wan-Rozita; J. Khairiah; B. S. Ismail

2009-01-01

114

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...

115

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 Californias 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...

116

Generic Escherichia coli contamination of spinach at the preharvest stage: effects of farm management and environmental factors.  

PubMed

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

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

2013-07-01

117

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

PubMed Central

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

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

2013-01-01

118

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

PubMed

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

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

2014-04-01

119

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

PubMed Central

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

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

2014-01-01

120

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

PubMed

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

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

2014-06-01

121

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

...without significant pest issues. Spinach, for example, has been permitted entry into the United States from Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama with only visual inspection, and L. huidobrensis...

2012-05-18

122

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...

123

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

E-print Network

with L-lactic acid, peroxyacetic acid, calcium hypochlorite, ozone, and chlorine dioxide. Inoculated spinach was exposed to e-beam irradiation and tested for counts of both pathogens immediately after irradiation treatment to determine bacterial reduction...

Neal, Jack A.

2010-07-14

124

Multiresidue pesticide analysis in ginseng and spinach by nontargeted and targeted screening procedures.  

PubMed

Five different mass spectrometers interfaced to GC or LC were evaluated for their application to targeted and nontargeted screening of pesticides in two foods, spinach and ginseng. The five MS systems were capillary GC/MS/MS, GC-high resolution time-of-flight (GC/HR-TOF)-MS, TOF-MS interfaced with a comprehensive multidimensional GC (GCxGC/TOF-MS), an MS/MS ion trap hybrid mass (qTrap) system interfaced with an ultra-performance liquid chromatograph (UPLC-qTrap), and UPLC interfaced to an orbital trap high resolution mass spectrometer (UPLC/Orbitrap HR-MS). Each MS system was tested with spinach and ginseng extracts prepared through a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure. Each matrix was fortified at 10 and 50 ng/g for spinach or 25 and 100 ng/g for ginseng with subsets of 486 pesticides, isomers, and metabolites representing most pesticide classes. HR-TOF-MS was effective in a targeted search for characteristic accurate mass ions and identified 97% of 170 pesticides in ginseng at 25 ng/g. A targeted screen of either ginseng or spinach found 94-95% of pesticides fortified for analysis at 10 ng/g with GC/MS/MS or LC/MS/MS using multiple reaction monitoring (MRM) procedures. Orbitrap-MS successfully found 89% of 177 fortified pesticides in spinach at 25 ng/g using a targeted search of accurate mass pseudomolecular ions in the positive electrospray ionization mode. A comprehensive GCxGC/TOF-MS system provided separation and identification of 342 pesticides and metabolites in a single 32 min acquisition with standards. Only 67 or 81% of the pesticides were identified in ginseng and spinach matrixes at 25 ng/g or 10 ng/g, respectively. MS/MS or qTrap-MS operated in the MRM mode produced the lowest false-negative rates, at 10 ng/g. Improvements to instrumentation, methods, and software are needed for efficient use of nontargeted screens in parallel with triple quadrupole MS. PMID:22320080

Hayward, Douglas G; Wong, Jon W; Zhang, Kai; Chang, James; Shi, Feng; Banerjee, Kaushik; Yang, Paul

2011-01-01

125

Spinach and tomato consumption increases lymphocyte DNA resistance to oxidative stress but this is not related to cell carotenoid concentrations  

Microsoft Academic Search

Summary\\u000a Background The increased consumption of fruit and vegetables has been linked to protection against different chronic diseases, but the\\u000a dietary constituents responsible for this association have not been clearly identified. Aim of the study We evaluated the effect of spinach and spinach+tomato puree consumption on cell DNA resistance to an oxidative stress. Methods To this aim, in a dietary

Marisa Porrini; Patrizia Riso; Giovannangelo Oriani

2002-01-01

126

Effect of nano-TiO 2 on strength of naturally aged seeds and growth of spinach  

Microsoft Academic Search

The effects of nano-TiO2 (rutile) and non-nano-TiO2 on the germination and growth of naturally aged spinach seeds were studied by measuring the germination rate and the germination\\u000a and vigor indexes of aged spinach seeds. An increase of these factors was observed at 0.254 nano-TiO2 treatment. During the growth stage, the plant dry weight was increased, as was the chlorophyll formation,

Lei Zheng; Fashui Hong; Shipeng Lu; Chao Liu

2005-01-01

127

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

Microsoft Academic Search

Mustard spinach plants were grown in mercury-spiked and contaminated soils collected in the field under controlled laboratory conditions over a full growth cycle to test if vegetation grown in these soils has discernible characteristics in visible\\/near-infrared (VNIR) spectra. Foliar Hg concentrations (0.1743.993ppm) of the Mustard spinach plants were positively correlated with Hg concentration of soils and varied throughout the growing

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

2007-01-01

128

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

Microsoft Academic Search

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

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

2008-01-01

129

Pressure Equilibrium and Jump Study on Unfolding of 23-kDa Protein from Spinach Photosystem II  

E-print Network

Pressure Equilibrium and Jump Study on Unfolding of 23-kDa Protein from Spinach Photosystem II Cui ABSTRACT Pressure-induced unfolding of 23-kDa protein from spinach photosystem II has been systematically is very sensitive to pressure. At 20°C and pH 5.5, 23-kDa protein shows a reversible two-state unfolding

Tian, Weidong

130

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

SciTech Connect

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.

Chunilall, V.; Kindness, A.; Jonnalagadda, S.B. [University of KwaZulu Natal, Durban (South Africa)

2006-07-01

131

Leaf mines: their effect on leaf longevity  

Microsoft Academic Search

The effects of a number of factors, notably leaf mining insects, on the longevity of beech and holm oak leaves have been studied. The regular monitoring of individually labelled leaves was complemented by analysis of leaf fall data. Both methods confirm that these mining insects have only a slight impact on their host trees. The presence of first generation Phyllonorycter

I. M. Pritchard; R. James

1984-01-01

132

Elm Leaf Beetle  

E-print Network

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

Patrick, Carl D.

2002-05-22

133

Spectral resolution of long term (0.5-50 s) delayed fluorescence from spinach chloroplasts.  

PubMed

The emission spectrum of room temperature delayed fluorescence from spinach chloroplasts does not change during the period 0.5-50 s after the cessation of illumination. This provides experimental evidence that charge recombination processes originating in various charge pairs of photosystem II, and manifest as various kinetical components of long term delayed fluorescence, result in the excitation of the same emitters, as predicted by the charge recombination hypothesis. PMID:1897939

Hideg, E; Scott, R Q; Inaba, H

1991-03-01

134

Effect of growth regulators and role of roots in sex expression in spinach  

Microsoft Academic Search

When 7-d-old plantlets of spinach (Spinacia oleracea L.) were immersed with their roots for 24 h in 25 mg\\/l gibberellic acid (GA3), or 15 mg\\/l 6-benzylaminopurine (6-BAP), or 15 mg\\/l indole-3-acetic acid (IAA), or 10 mg\\/l abscisic acid (ABA) and subsequently grown on long (18-h) days, the ratio of plants with male and female flowers, which in the controls was

M. Kh. Chailakhyan; V. N. Khryanin

1978-01-01

135

Molecular cloning of GA 2-oxidase3 from spinach and its ectopic expression in Nicotiana sylvestris.  

PubMed

Previous work has shown that 13-hydroxylated gibberellins (GAs) are predominant in the long-day (LD) plant spinach (Spinacia oleracea; GA53, GA44, GA19, GA20, GA1, GA8, and GA29). Also present in spinach are 2-hydroxylated C20-GAs: GA97, GA98, GA99, and GA110. Levels of the most abundant GA, GA97, decreased when plants were transferred from short photoperiods (SD) to LD. When [14C]GA53 was fed to spinach plants, more GA53 was converted to GA97 in SD than in LD, and more radioactive GA20 was formed in LD than in SD. SoGA2ox3, encoding a GA 2-oxidase, was isolated from spinach. The recombinant protein converted only two C20-GA precursors, GA12 and GA53, to their respective products, GA110 and GA97. GA2ox3 competes with GA20ox1 for their common substrate, GA53. In SD, deactivation to GA97 prevails, whereas in LD conversion to GA20 is favored. Transcript levels of SoGA2ox3 were higher in shoot tips than in blades, petioles, and young leaves. Ectopic expression of SoGA2ox3 in the long-day plant Nicotiana sylvestris showed a range of dwarf phenotypes, such as reduced germination, short hypocotyl and stem, dark-green leaves, and late flowering, but normal flowers and seed production. The levels of GA53 and GA1 were 3- to 5-fold lower in transgenic plants than in wild type, whereas the levels of GA97 and GA110 increased 3- to 6-fold in transgenic plants. It is concluded that genetic manipulation of plant stature by increasing deactivation of precursors of active GA is more advantageous than increased deactivation of bioactive GA1 itself. PMID:15821147

Lee, Dong Ju; Zeevaart, Jan A D

2005-05-01

136

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

PubMed Central

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

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

2008-01-01

137

Characterization and identification of two virus diseases of spinach in South Texas  

E-print Network

by Kunkel in 1926 (19). Spinach plants were experimentally inoculated from infected asters using leafhopper s. This pathogen was believed to be a virus until 1978 when it was demonstrated by Maramorosch and Kondo (20) that a spi roplasma (~Siro...). Infected plants are dwarfed and slightly chlorotic with many upright secondary shoots which form a multiple crown. The pathogen is not transmitted mechanically, but it is vectored by several species of leafhopper. Aster yellows is wide- spread...

Adams, Edward Blair

1979-01-01

138

Inactivation of ribulosebisphosphate carboxylase by modification of arginyl residues with phenylglyoxal. [Spinach, Rhodospirillum rubrum  

Microsoft Academic Search

Phenylglyoxal rapidly and completely inactivates spinach and Rhodospirillum rubrum ribulosebiphosphate carboxylases. Inactivation exhibits pseudo-first-order kinetics and a reaction order of approximately one for both enzymes, suggesting that modification of a single residue per protomeric unit suffices for inactivation. Loss of enzymic activity is directly proportional to incorporation of (¹⁴C)phenylglyoxal until only 30% of the initial activity remains. For both enzymes,

J. V. Schloss; I. L. Norton; C. D. Stringer; F. C. Hartman

1978-01-01

139

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

SciTech Connect

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.

Sakaki, Takeshi; Saito, Kazuki; Kawaguchi, Akihiko; Kondo, Noriaki; Yamada, Mitsuhiro (National Institute for Environmental Studies, Ibaraki (Japan) Keio Univ., Tokyo (Japan) Univ. of Tokyo (Japan))

1990-10-01

140

Molecular Characterization and Subcellular Localization of Protoporphyrinogen Oxidase in Spinach Chloroplasts1  

PubMed Central

Protoporphyrinogen oxidase (Protox) is the last common enzyme in the biosynthesis of chlorophylls and heme. In plants, there are two isoenzymes of Protox, one located in plastids and other in the mitochondria. We cloned the cDNA of spinach (Spinacia oleracea) plastidal Protox and purified plastidal Protox protein from spinach chloroplasts. Sequence analysis of the cDNA indicated that the plastid Protox of spinach is composed of 562 amino acids containing the glycine-rich motif GxGxxG previously proposed to be a dinucleotide binding site of many flavin-containing proteins. The cDNA of plastidal Protox complemented a Protox mutation in Escherichia coli. N-terminal sequence analysis of the purified enzyme revealed that the plastidal Protox precursor is processed at the N-terminal site of serine-49. The predicted transit peptide (methionine-1 to cysteine-48) was sufficient for the transport of precursors into the plastid because green fluorescent protein fused with the predicted transit peptide was transported to the chloroplast. Immunocytochemical analysis using electron microscopy showed that plastidal Protox is preferentially associated with the stromal side of the thylakoid membrane, and a small portion of the enzyme is located on the stromal side of the chloroplast inner envelope membrane. PMID:10982422

Che, Fang-Sik; Watanabe, Naohide; Iwano, Megumi; Inokuchi, Hachiro; Takayama, Seiji; Yoshida, Shigeo; Isogai, Akira

2000-01-01

141

Employing Response Surface Methodology for the Optimization of Ultrasound Assisted Extraction of Lutein and ?-Carotene from Spinach.  

PubMed

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

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

2015-01-01

142

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...

143

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...

144

Mapping leaf surface landscapes.  

PubMed Central

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. Images Fig. 1 PMID:11607676

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

1996-01-01

145

Low molecular weight subunits associated with the cytochrome b 6 f complexes from spinach and Chlamydomonas reinhardtii.  

PubMed

Cytochrome b 6 f complexes, prepared from spinach and Chlamydomonas thylakoids, have been examined for their content of low molecular weight subunits. The spinach complex contains two prominent low molecular weight subunits of 3.7 and 4.1 kD while a single prominent component of 4.5 kD was present in the Chlamydomonas complex. An estimation of the relative stoichiometry of these subunits suggests several are present at levels approximating one copy per cytochrome complex. The low molecular weight subunits were purified by reversed phase HPLC and N-terminal sequences obtained. Both the spinach and Chlamydomonas cytochrome complexes contain a subunit that is identified as the previously characterized petG gene product (4.8 kD in spinach and 4.1 kD in Chlamydomonas). A second subunit (3.8 kD in spinach and 3.7 kD in Chlamydomonas) appears to be homologous in the two complexes and is likely to be a nuclear gene product. The possible presence of other low molecular weight subunits in these complexes is also considered. PMID:24317832

Schmidt, C L; Malkin, R

1993-10-01

146

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

PubMed

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

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

2015-08-01

147

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

PubMed Central

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

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

1992-01-01

148

Assessing soybean leaf area and leaf biomass by spectral measurements  

NASA Technical Reports Server (NTRS)

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.

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

1979-01-01

149

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...

150

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 ...

151

Leaf Pack Network  

NSDL National Science Digital Library

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

152

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

PubMed Central

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

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

1991-01-01

153

Leaf development and morphogenesis.  

PubMed

The development of plant leaves follows a common basic program that is flexible and is adjusted according to species, developmental stage and environmental circumstances. Leaves initiate from the flanks of the shoot apical meristem and develop into flat structures of variable sizes and forms. This process is regulated by plant hormones, transcriptional regulators and mechanical properties of the tissue. Here, we review recent advances in the understanding of how these factors modulate leaf development to yield a substantial diversity of leaf forms. We discuss these issues in the context of leaf initiation, the balance between morphogenesis and differentiation, and patterning of the leaf margin. PMID:25371359

Bar, Maya; Ori, Naomi

2014-11-01

154

Factors affecting the quality of freeze-dried and compressed spinach  

E-print Network

(savoy) and Reisto Flay(flat), The three least desirable were Morgreen(flat), 4612 (savoy) and Bonus(semi-savoy). This indicates that leaftype may not be critical in producing freeze-dried compressed spinach. ACKNOWLEDGMENTS The author w1shes to express h1s... varied from 9. 88 in Dixie Market (savoy) to 11. 52 in Resito Flay (flat). The percentage of dry matter in cooked leaftypes ranged from 7. 77 in flat to 10. 00 in savoy; Cultivars varied from 6. 88 in Norgreen (flat) to 11. 36 in Bonus (semi...

Wisakowsky, Eugene Edward

1975-01-01

155

In vivo and in vitro effects of ethephon on some oxidative enzymes in spinach leaves  

Microsoft Academic Search

In vivo and in vitro effects of ethephon, an ethylene-generating compound, on some oxidative enzymes; polyphenol oxidase (PPO,\\u000a 1.10.3.1), peroxidase (POD, 1.11.1.7) and catalase (CAT, 1.11.1.6) in spinach leaves were investigated. The plants were grown\\u000a under controlled conditions in sand culture in 60days. Ethephon was applied as two doses at 0.1 and 1mM. The leaves were\\u000a harvested in the first

Lokman ztrk; . ?rfan Kfrevio?lu; Yavuz Demir

2008-01-01

156

Relationships Between Angular Leaf Spot, Healthy Leaf Area, Effective Leaf Area and Yield of Phaseolus vulgaris  

Microsoft Academic Search

Three field experiments were carried out with the bean cultivar Carioca Comum to investigate the relationships among visual and virtual severity of angular leaf spot (caused by Phaeoisariopsis griseola), area under visual and virtual disease progress curves (AUDPC), healthy leaf area index on any given day (HLAI), healthy leaf area duration (HAD), healthy leaf area absorption (HAA), effective leaf area

W. C. Jesus Junior; F. X. R. Vale; R. R. Coelho; P. A. Paul; B. Hau; A. Bergamin Filho; L. Zambolim; R. D. Berger

2003-01-01

157

Leaf Hydraulics Lawren Sack1  

E-print Network

Leaf Hydraulics Lawren Sack1 and N. Michele Holbrook2 1 Department of Botany, University of Hawai influence rates of transpiration and photosynthesis. Leaf hydraulic conductance (Kleaf) varies more than 65. #12;Contents INTRODUCTION. . . . . . . . . . . . . . . . . 362 LEAF HYDRAULIC CONDUCTANCE

Holbrook, N. Michele

158

Yellow leaf blotch  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

159

ASCOCHYTA LEAF SPOT  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

160

Leaf cutter ants  

NSDL National Science Digital Library

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

N/A N/A (None; )

2007-12-15

161

LEAF MARGIN INFLORESCENCE  

E-print Network

leaves typical of smartweeds typical of most biennials & some winter annuals typical of many plant{ LEAF BLADE LEAF MARGIN PETIOLE INFLORESCENCE WS-27-W Guidelines for Submitting Digital Plant Assistant Professor of Weed Science Purdue University The accuracy of identifying a plant from digital

Holland, Jeffrey

162

Solution Structures of Spinach Acyl Carrier Protein with Decanoate and Stearate  

PubMed Central

Acyl carrier protein (ACP) is a cofactor in a variety of biosynthetic pathways, including fatty acid metabolism. Thus it is of interest to determine structures of physiologically relevant ACP-fatty acid complexes. We report here the NMR solution structures of spinach ACP with decanoate (10:0-ACP) and stearate (18:0-ACP) attached to the 4? phosphopantetheine prosthetic group. The protein in the fatty acid complexes adopts a single conformer, unlike apo- and holo-ACP, which interconvert in solution between two major conformers. The protein component of both 10:0- and 18:0-ACP adopts the four-helix bundle topology characteristic of ACP, and a fatty acid binding cavity was identified in both structures. Portions of the protein close in space to the fatty acid and the 4? phosphopantetheine were identified using filtered/edited NOESY experiments. A docking protocol was used to generate protein structures containing bound fatty acid for 10:0- and 18:0-ACP. In both cases, the predominant structure contained fatty acid bound down the center of the helical bundle, in agreement with the location of the fatty acid binding pockets. These structures demonstrate the conformational flexibility of spinach-ACP and suggest how the protein changes to accommodate its myriad binding partners. PMID:16618110

Zornetzer, Gregory A.; Fox, Brian G.; Markley, John L.

2008-01-01

163

Characterization of the secondary structure and thermostability of the extrinsic 16 kilodalton protein of spinach photosystem II by  

E-print Network

denaturation due to an irreversible protein aggregation occurs with a conforma- tional transition at t 65 C; PSII, photosystem II; SDS, sodium dodecyl sulfate www.elsevier.nl/locate/molstruc #12;proteins (denoted protein of spinach photosystem II by Fourier transform infrared spectroscopy H. Zhanga,1 , Y. Yamamotob

Carpentier, Robert

164

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...

165

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 ...

166

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,...

167

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 ...

168

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

PubMed

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 plant's 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

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

2013-01-01

169

Estimating Near-Infrared Leaf Reflectance from Leaf Structural Characteristics  

Microsoft Academic Search

The relationship between near-infrared reflectance at 800 nm (NIRR) from leaves and characteristics of leaf structure known to affect photosynthesis was investigated in 48 species of alpine angiosperms. This wavelength was selected to discriminate the effects of leaf structure vs. chemical or water content on leaf reflectance. A quantitative model was first constructed correlating NIRR with leaf structural characteristics for

Michele R. Slaton; E. Raymond Hunt; William K. Smith

2001-01-01

170

Four-Leaf Clover  

NSDL National Science Digital Library

Scientist-in-training Summer Praetorius has an unusual skillshe is really, really good at spotting four-leaf clovers (Trifolium repens L.). A single gene causes the normally three-leafed clover to produce a fourth, supposedly lucky, leaf. As it turns out, good science depends on both close observationa skill Praetorius uses to spot tiny shelled animals called foraminiferaand a little bit of luck. Ari Daniel Shapiro explains. Also included is a Learn More section that provides background information on the scientists recorded in the podcast, lessons, images, and cool facts.

2009-01-01

171

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

SciTech Connect

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.

Zeevaart, J.A.D.; Gage, D.A.; Talon, M. (Michigan State Univ., East Lansing (United States))

1993-08-01

172

Electronic Leaf Project  

NSDL National Science Digital Library

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

Carolyn Houston

2000-05-01

173

Leaf to Landscape  

Microsoft Academic Search

\\u000a One fundamental problem for maximizing carbon gain at the leaf and higher organizational levels entails the link between\\u000a light capture and leaf energy budgets. The balance between the two processes, however, depends on the environment. For example,\\u000a shade environments limit carbon gain due to low light levels, and so we would expect plants to display traits that maximize\\u000a light interception

Stanley D. Smith; Elke Naumburg; Lo Niinemets; Matthew J. Germino

174

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

175

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

SciTech Connect

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.

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

2010-01-01

176

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

PubMed

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

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

2014-10-01

177

Deer predation on leaf miners via leaf abscission  

NASA Astrophysics Data System (ADS)

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.

Yamazaki, Kazuo; Sugiura, Shinji

2008-03-01

178

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

SciTech Connect

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.

McKenna, I.M.; Keach, R.M. Jr; Williams, F.M. (Pennsylvania State Univ., University Park (United States)); Chaney, R.L. (Pennsylvania State Univ., University Park (United States) Dept. of Agriculture, Beltsville, MD (United States)); Tao, Shyy-Hwa (Food and Drug Administration, Washington, DC (United States))

1992-02-01

179

A novel protecting method for visual green color in spinach puree treated by high intensity pulsed electric fields  

Microsoft Academic Search

Green vegetables is easily to lose green color during processing and storage. In this paper a novel high intensity pulsed electric field (PEF) technique is applied to process spinach puree with dissoluble zinc salt. Various experimental conditions of the PEF process, such as water-soluble Zn2+ ion concentration (20200ppm), electric field strength (20100kV\\/cm) and storing temperature (25C and 37C), were investigated

Yongguang Yin; Yong Han; Jingbo Liu

2007-01-01

180

Identification of a Protein That lnhibits the Phosphorylated Form of Nitrate Reductase from Spinach (Spina cia olera cea) Leaves  

Microsoft Academic Search

The low-activity, phosphorylated form of nitrate reductase (NR) became activated during purification from spinach (Spinacia olera- cea) leaves harvested in the dark. This activation resulted from its separation from an approximately 110-kD nitrate reductase inhib- itor protein (NIP). Readdition of NIP inactivated the purified phos- phorylated NR, but not the active dephosphorylated form of NR, indicating that the inactivation of

Pauline Douglas; Cathrine Lillo

181

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

PubMed

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

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

2014-05-01

182

Living in the Leaf Litter  

NSDL National Science Digital Library

This online article, from the museum's Musings newsletter for educators, provides some mind-boggling facts about leaf litter. It has an overview of what leaf litter is and how it's produced and a link for further research.

183

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

PubMed Central

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 CalvinBensonBassham 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 dont 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?molh?1mg?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

MacLeod, John K.

2006-01-01

184

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...

185

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...

186

Science Nation: Leaf Sensor  

NSDL National Science Digital Library

Who might know more about what a plant needs than a farmer or a greenhouse owner? How about the plant itself? What if plants could tell us when they are thirsty? With funding from the National Science Foundation (NSF), AgriHouse has developed a leaf sensor that is enabling plants to do just that.

187

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...

188

Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism  

PubMed Central

Background Evolution of unisexual flowers entails one of the most extreme changes in plant development. Cultivated spinach, Spinacia oleracea L., is uniquely suited for the study of unisexual flower development as it is dioecious and it achieves unisexually by the absence of organ development, rather than by organ abortion or suppression. Male staminate flowers lack fourth whorl primordia and female pistillate flowers lack third whorl primordia. Based on theoretical considerations, early inflorescence or floral organ identity genes would likely be directly involved in sex-determination in those species in which organ initiation rather than organ maturation is regulated. In this study, we tested the hypothesis that sexual dimorphism occurs through the regulation of B class floral organ gene expression by experimentally knocking down gene expression by viral induced gene silencing. Results Suppression of B class genes in spinach resulted in the expected homeotic transformation of stamens into carpels but also affected the number of perianth parts and the presence of fourth whorl. Phenotypically normal female flowers developed on SpPI-silenced male plants. Suppression of the spinach C class floral organ identity gene, SpAG, resulted in loss of reproductive organ identity, and indeterminate flowers, but did not result in additional sex-specific characteristics or structures. Analysis of the genomic sequences of both SpAP3 and SpPI did not reveal any allelic differences between males and females. Conclusion Sexual dimorphism in spinach is not the result of homeotic transformation of established organs, but rather is the result of differential initiation and development of the third and fourth whorl primordia. SpAG is inferred to have organ identity and meristem termination functions similar to other angiosperm C class genes. In contrast, while SpPI and SpAP3 resemble other angiosperms in their essential functions in establishing stamen identity, they also appear to have an additional function in regulating organ number and identity outside of the third whorl. We present a model for the evolution of dioecy in spinach based on the regulation of B class expression. PMID:20226063

2010-01-01

189

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

SciTech Connect

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.

Andrews, J.C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; [Lawrence Berkeley Lab., CA (United States). Structural Biology Div.

1995-08-01

190

Envelope Membranes from Spinach Chloroplasts Are a Site of Metabolism of Fatty Acid Hydroperoxides.  

PubMed Central

Enzymes in envelope membranes from spinach (Spinacia oleracea L.) chloroplasts were found to catalyze the rapid breakdown of fatty acid hydroperoxides. In contrast, no such activities were detected in the stroma or in thylakoids. In preparations of envelope membranes, 9S-hydroperoxy-10(E),12(Z)-octadecadienoic acid, 13S-hydroperoxy-9(Z),11(E)-octadecadienoic acid, or 13S-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoic acid were transformed at almost the same rates (1-2 [mu]mol min-1 mg-1 protein). The products formed were separated by reversed-phase high-pressure liquid chromatography and further characterized by gas chromatography-mass spectrometry. Fatty acid hydroperoxides were cleaved (a) into aldehydes and oxoacid fragments, corresponding to the functioning of a hydroperoxide lyase, (b) into ketols that were spontaneously formed from allene oxide synthesized by a hydroperoxide dehydratase, (c) into hydroxy compounds synthesized enzymatically by a system that has not yet been characterized, and (d) into oxoenes resulting from the hydroperoxidase activity of a lipoxygenase. Chloroplast envelope membranes therefore contain a whole set of enzymes that catalyze the synthesis of a variety of fatty acid derivatives, some of which may act as regulatory molecules. The results presented demonstrate a new role for the plastid envelope within the plant cell. PMID:12226196

Blee, E.; Joyard, J.

1996-01-01

191

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

PubMed Central

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

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

1986-01-01

192

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

PubMed Central

Four cDNAs encoding phosphoribosyl diphosphate (PRPP) synthase were isolated from a spinach (Spinacia oleracea) cDNA library by complementation of an Escherichia coli ?prs 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

Krath, Britta N.; Hove-Jensen, Bjarne

1999-01-01

193

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

PubMed Central

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

Balakrishna, AshaManikkoth; Seelert, Holger; Marx, Sven-Hendric; Dencher, NorbertA.; Grber, Gerhard

2014-01-01

194

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

PubMed

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

Schmidt, H; Heinz, E

1993-02-01

195

Mitochondrial phylogeny reveals intraspecific variation in Peronospora effusa, the spinach downy mildew pathogen.  

PubMed

Since about two hundred years, downy mildew caused by Peronospora effusa is probably the most economically important disease of spinach (Spinacia oleracea). However, there is no information on the global phylogeographic structure of the pathogen and thus it is unclear whether a single genotype occurs worldwide or whether some local genetic variation exists. To investigate the genetic variability of this pathogen, a sequence analysis of two partial mitochondrial DNA genes, cox2 and nad1, was carried out. Thirty-three specimens of Peronospora effusa from four continents were analyzed, including samples from Australia, China, Japan, Korea, Mexico, Russia, Sweden, and the USA. Despite the potential anthropogenic admixture of genotypes, a phylogeographic pattern was observed, which corresponds to two major groups, an Asian/Oceanian clade and another group, which includes American/European specimens. Notably, two of six Japanese specimens investigated did not belong to the Asian/Oceanian clade, but were identical to three of the specimens from the USA, suggestive of a recent introduction from the USA to Japan. As similar introduction events may be occurring as a result of the globalised trade with plant and seed material, a better knowledge of the phylogeographic distribution of pathogens is highly warranted for food security purposes. PMID:22203571

Choi, Young-Joon; Thines, Marco; Han, Jae-Gu; Shin, Hyeon-Dong

2011-12-01

196

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

PubMed

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

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

2014-02-13

197

Measurement of Ribulose 1,5-Bisphosphate from Spinach Chloroplasts 1  

PubMed Central

A technique has been developed for the rapid and simple measurement of ribulose 1,5-bisphosphate from isolated spinach chloroplasts. The endogenous ribulose bisphosphate was detected enzymically using 14CO2 and ribulose bisphosphate carboxylase/oxygenase released from the chloroplasts. Ribulose 5-phosphate kinase was inhibited with 0.4 to 0.6 millimolar 2,6-dichlorophenol-indophenol and 4 micromolar carbonyl cyanide m-chlorophenylhydrazone. Phosphoenolpyruvate carboxylase activity was low with washed chloroplasts and its labeled product, [14C]oxalacetate, was destroyed by heating with 1.0 n HCl at 90 C. The assay method was linear from 0.05 to 0.87 nanomoles ribulose bisphosphate per milliliter. The latter value was determined with chloroplast material having 44 micrograms of chlorophyll per milliliter. This technique was simple and direct, used less chloroplast material, yet provided results comparable to a previously described enzymic technique in which ribulose bisphosphate was determined after the precipitation of chloroplast proteins by perchloric acid. PMID:16661073

Sicher, Richard C.; Bahr, James T.; Jensen, Richard G.

1979-01-01

198

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

PubMed

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 80kHz), exposure time (5, 10, 15, 20, 25, and 30min), temperature (30, 40, and 50C), and ultrasonic power (30%, 50%, and 70%). The best conditions for extraction yields were ultrasonic frequency of 37kHz, extraction time of 30min, reaction temperature of 40C, 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 (64.8821.84, 33.9611.30, 27.3711.85, 64.1816.69 and 70.259.68). 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

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

2015-05-01

199

In-vitro degradation of starch granules isolated from spinach chloroplasts.  

PubMed

The initial reactions of transitory starch degradation in Spinacia oleracea L. were investigated using an in-vitro system composed of native chloroplast starch granules, purified chloroplast and non-chloroplast forms of phosphorylase (EC 2.4.1.1) from spinach leaves, and ?-amylase (EC 3.2.1.1) isolated from Bacillus subtilis. Starch degradation was followed by measuring the release of soluble glucans, by determining phosphorylase activity, and by an electron-microscopic evaluation following deep-etching of the starch granules. Starch granules were readily degraded by ?-amylase but were not a substrate for the chloroplast phosphorylase. Phosphorolysis and glucan synthesis by this enzyme form were strictly dependent upon a preceding amylolytic attack on the starch granules. In contrast, the non-chloroplast phosphorylase was capable of using starch-granule preparations as substrate. Hydrolytic degradation of the starch granules was initiated at the entire particle surface, independently of its size. As a result of amylolysis, soluble glucans were released with a low degree of polymerization. When assayed with these glucans as substrate, the chloroplast phosphorylase form exhibited a higher apparent affinity and a higher reaction velocity compared with the non-chloroplast phosphorylase form. It is proposed that transitory starch degradation in vivo is initiated by hydrolysis; phosphorolysis is most likely restricted to a pool of soluble glucan intermediates. PMID:24264852

Steup, M; Robenek, H; Melkonian, M

1983-08-01

200

Leaf absorbance and photosynthesis  

NASA Technical Reports Server (NTRS)

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.

Schurer, Kees

1994-01-01

201

7 CFR 29.3648 - Thin Leaf (C Group).  

Code of Federal Regulations, 2010 CFR

...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Leaf. Mature, thin, firm leaf structure, crepy, oily, normal...

2010-01-01

202

7 CFR 29.3648 - Thin Leaf (C Group).  

Code of Federal Regulations, 2011 CFR

...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Leaf. Mature, thin, firm leaf structure, crepy, oily, normal...

2011-01-01

203

7 CFR 29.3648 - Thin Leaf (C Group).  

Code of Federal Regulations, 2014 CFR

...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Leaf. Mature, thin, firm leaf structure, crepy, oily, normal...

2014-01-01

204

7 CFR 29.3648 - Thin Leaf (C Group).  

Code of Federal Regulations, 2012 CFR

...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Leaf. Mature, thin, firm leaf structure, crepy, oily, normal...

2012-01-01

205

7 CFR 29.3648 - Thin Leaf (C Group).  

Code of Federal Regulations, 2013 CFR

...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Thin Leaf. Ripe, thin, open leaf structure, smooth, oily, clear finish...Leaf. Mature, thin, firm leaf structure, crepy, oily, normal...

2013-01-01

206

Leaf-to-leaf distances in Catalan tree graphs  

E-print Network

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

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

2015-03-02

207

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

PubMed

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

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

2015-03-01

208

Preparation of isotopically labeled spinach acyl-acyl carrier protein for NMR structural studies.  

PubMed

Acyl carrier proteins (ACPs) are important protein cofactors in fatty acid biosynthesis, but their acylated forms have not been well-studied. To permit detailed nuclear magnetic resonance studies of acylated spinach ACP isoform I, we have developed a new expression plasmid for recombinant production of the apo-protein and modified protocols for purifying the protein product and acylating it to form acyl-ACP. To solve plasmid stability problems associated with growth in minimal media, the ampicillin resistance gene from pSACP-2a was replaced with the tetA(C) gene from pBR322. The resulting plasmid, pSACP-2t, supported overexpression of apo-ACP in Escherichia coli BL21(DE3) cells in M9 medium containing 15NH4Cl as the sole nitrogen source. Apo-ACP was purified to homogeneity by means of polyethylene glycol precipitation and anion exchange. Two in vitro synthetic routes were used to produce acyl-ACPs. In one route, apo-ACP was converted to the holo form and the acyl form by a published protocol that employs a discrete enzymatic reaction for each step. As an alternative route to produce decanoyl-ACP, apo-ACP was directly converted to the acyl form by using holo-ACP synthase along with the non-natural substrate decanoyl-CoA. Two-dimensional 1H-15N NMR spectroscopy of decanoyl-ACP and stearoyl-ACP revealed that changes in the length of the covalently attached fatty acid do not affect the secondary structure of the protein but do influence the local conformation and dynamics. PMID:16325425

Zornetzer, Gregory A; White, Robert D; Markley, John L; Fox, Brian G

2006-04-01

209

Dark-adapted spinach thylakoid protein heterogeneity offers insights into the photosystem II repair cycle.  

PubMed

In higher plants, thylakoid membrane protein complexes show lateral heterogeneity in their distribution: photosystem (PS) II complexes are mostly located in grana stacks, whereas PSI and adenosine triphosphate (ATP) synthase are mostly found in the stroma-exposed thylakoids. However, recent research has revealed strong dynamics in distribution of photosystems and their light harvesting antenna along the thylakoid membrane. Here, the dark-adapted spinach (Spinacia oleracea L.) thylakoid network was mechanically fragmented and the composition of distinct PSII-related proteins in various thylakoid subdomains was analyzed in order to get more insights into the composition and localization of various PSII subcomplexes and auxiliary proteins during the PSII repair cycle. Most of the PSII subunits followed rather equal distribution with roughly 70% of the proteins located collectively in the grana thylakoids and grana margins; however, the low molecular mass subunits PsbW and PsbX as well as the PsbS proteins were found to be more exclusively located in grana thylakoids. The auxiliary proteins assisting in repair cycle of PSII were mostly located in stroma-exposed thylakoids, with the exception of THYLAKOID LUMEN PROTEIN OF 18.3 (TLP18.3), which was more evenly distributed between the grana and stroma thylakoids. The TL29 protein was present exclusively in grana thylakoids. Intriguingly, PROTON GRADIENT REGULATION5 (PGR5) was found to be distributed quite evenly between grana and stroma thylakoids, whereas PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE1 (PGRL1) was highly enriched in the stroma thylakoids and practically missing from the grana cores. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. PMID:24296034

Suorsa, Marjaana; Rantala, Marjaana; Danielsson, Ravi; Jrvi, Sari; Paakkarinen, Virpi; Schrder, Wolfgang P; Styring, Stenbjrn; Mamedov, Fikret; Aro, Eva-Mari

2014-09-01

210

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

SciTech Connect

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.

Singh, K.K.; Gibbs, M. (Brandeis Univ., Waltham, MA (United States))

1993-05-01

211

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

PubMed

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

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

212

Leaf development: a cellular perspective  

PubMed Central

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

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

2014-01-01

213

Impact of spinach consumption on DNA stability in peripheral lymphocytes and on biochemical blood parameters: results of a human intervention trial  

Microsoft Academic Search

IntroductionA controlled intervention trial was conducted to assess the impact of spinach consumption on DNA stability in lymphocytes\\u000a and on health-related biochemical parameters.\\u000a \\u000a \\u000a \\u000a \\u000a MethodsThe participants (n=8) consumed homogenised spinach (225g\\/day\\/person) over a period of 16days. DNA migration was monitored in single cell\\u000a gel electrophoresiscomet assays under standard conditions, which reflect single- and double-strand breaks, after treatment\\u000a of nuclei with lesion-specific

Beate Moser; Thomas Szekeres; Christian Bieglmayer; Karl-Heinz Wagner; Miroslav Mik; Michael Kundi; Oliwia Zakerska; Armen Nersesyan; Nina Kager; Johann Zahrl; Christine Hoelzl; Veronika Ehrlich; Siegfried Knasmueller

214

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

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

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

2013-07-01

215

Estimating Corn Leaf Chlorophyll Concentration from Leaf and Canopy Reflectance  

Microsoft Academic Search

Farmers must balance the competing goals of supplying adequate N for their crops while minimizing N losses to the environment. To characterize the spatial variability of N over large fields, traditional methods (soil testing, plant tissue analysis, and chlorophyll meters) require many point samples. Because of the close link between leaf chlorophyll and leaf N concentration, remote sensing techniques have

C. S. T. Daughtry; C. L. Walthall; M. S. Kim; E. Brown de Colstoun; J. E. McMurtrey III

2000-01-01

216

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

E-print Network

the structure of leaf veins and areoles. Citation to follow. Introduction The LEAF GUI software LEAF GUI: User Manual (Leaf Extraction and Analysis Framework Graphical User Interface) #12;LEAF GUI User Manual Price et al. Index How to cite the LEAF GUI

Weitz, Joshua S.

217

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

218

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

219

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

220

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture... Standards Definitions 29.6023 Leaf structure. The cell development of a leaf as indicated by its porosity. The...

2010-01-01

221

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture... Standards Definitions 29.6023 Leaf structure. The cell development of a leaf as indicated by its porosity. The...

2011-01-01

222

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

PubMed Central

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

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

2014-01-01

223

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

PubMed

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

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

2014-01-01

224

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

SciTech Connect

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.

Singh, K.K.; Changguo Chen; Gibbs, M. (Brandeis Univ., Waltham, MA (United States))

1993-04-01

225

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

PubMed

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

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

2013-04-01

226

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...

227

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...

228

Pressure-exploration of the 33-kDa protein from the spinach photosystem II particle.  

PubMed

The 33-kDa protein isolated from the spinach photosystem II particle is an ideal model to explore high-pressure protein-unfolding. The protein has a very low free energy as previously reported by chemical unfolding studies, suggesting that it must be easy to modulate its unfolding transition by rather mild pressure. Moreover, the protein molecule consists of only one tryptophan residue (Trp241) and eight tyrosine residues, which can be conveniently used to probe the protein conformation and structural changes under pressure using either fluorescence spectroscopy or fourth derivative UV absorbance spectroscopy. The different experimental methods used in the present study indicate that at 20 degrees C and pH 6, the 33-kDa protein shows a reversible two-state unfolding transition from atmospheric pressure to about 180 MPa. This value is much lower than those found for the unfolding of most proteins studied so far. The unfolding transition induces a large red shift of the maximum fluorescence emission of 34 nm (from 316 nm to 350 nm). The change in standard free energy (DeltaGo) and in volume (DeltaV) for the transition at pH 6.0 and 20 degrees C are -14.6 kJ.mol-1 and -120 mL.mol-1, respectively, in which the DeltaGo value is consistent with that obtained by chemical denaturation. We found that pressure-induced protein unfolding is promoted by elevated temperatures, which seem largely attributed to the decrease in the absolute value of DeltaGo (only a minor variation was observed for the DeltaV value). However, the promotion of the unfolding by alkaline pH seems mainly related to the increase in DeltaV without any significant changes in DeltaGo. It was also found that NaCl significantly protects the protein from pressure-induced unfolding. In the presence of 1 M NaCl, the pressure needed to induce the half-unfold of the protein is shifted to a higher value (shift of 75 MPa) in comparison with that observed without NaCl. Interestingly, in the presence of NaCl, the value of DeltaV is significantly reduced whilst that of DeltaGo remains as before. The unfolding-refolding kinetics of the protein has also been studied by pressure-jump, in which it was revealed that both reactions are a two-state transition process with a relatively slow relaxation time of about 102 s. PMID:11322896

Ruan, K; Xu, C; Yu, Y; Li, J; Lange, R; Bec, N; Balny, C

2001-05-01

229

Oxygen-18 and deuterium labeling studies of choline oxidation by spinach and sugar beet.  

PubMed

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 O(2)- 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 vivo(18)O- and (2)H-labeling in conjunction with fast atom bombardment mass spectrometry to test for two hypothetical choline-oxidizing reactions that would explain the observed requirements for O(2) and reductant: a desaturase or an oxygenase. Simple syntheses for (2)H(3)-choline, (2)H(3), (18)O-choline, and (2)H(3), (18)O-betaine are given. A desaturase mechanism was sought by giving choline deuterated at the 2-carbon, or choline unlabeled at this position together with (2)H(2)O and by analyzing newly synthesized betaine. About 15% of the (2)H at C-2 was lost during oxidation of choline to betaine, and about 10% of the betaine made in the presence of 50% (2)H(2)O was monodeuterated. These small effects are more consistent with chemical exchange than with a desaturase, because 10 to 15% losses of (2)H 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 (18)O from (18)O(2) into newly synthesized betaine was compared with that from (18)O-labeled choline, in light and darkness. Incorporation of (18)O from (18)O-choline was readily detectable and varied from about 15 to 50% of the theoretical maximum value; the (18)O losses were attributable to exchange of the intermediate betaine aldehyde with water. In darkness, incorporation of (18)O from (18)O(2) approached that from (18)O-choline, but in the light was severalfold lower, presumably due to isotopic dilution by photosynthetic (16)O(2). These data indicate that the chloroplast choline-oxidizing enzyme is an oxygenase. PMID:16666370

Lerma, C; Hanson, A D; Rhodes, D

1988-11-01

230

The basis for variation in leaf longevity of plants  

Microsoft Academic Search

Any theory of leaf phenology must predict leaf longevity, leaf habit, leaf expansion and its timing among other variables. These phenological traits may be important keys to understand the response of trees to climatic change. Here I concentrate on and review two of these critical phenological traits, leaf longevity and leaf habit. Theories of leaf longevity were re-evaluated and leaf

Kihachiro Kikuzawa

1995-01-01

231

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 ...

232

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

Microsoft Academic Search

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

Anne Krapp; W. Paul Quick; Mark Stitt

1991-01-01

233

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...

234

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...

235

Market Response to a Food Safety Shock: The 2006 Foodborne Illness Outbreak of E. coli O157:H7 Linked to Spinach  

Microsoft Academic Search

In 2006 FDA announced that consumers should not eat fresh spinach in the wake of a large foodborne illness outbreak of E. coli O157:H7. This paper investigates response of consumers to the announcement. We use an AIDS demand model with 5 food safety shock variables and retail scanner data to analyze market response. Even fifteen months after the outbreak, predicted

Carlos A. Arnade; Linda Calvin; Fred Kuchler

2008-01-01

236

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...

237

Speciation of Cd and Zn in contaminated soils assessed by DGT-DIFS, and WHAM\\/Model VI in relation to uptake by spinach and ryegrass  

Microsoft Academic Search

A pot experiment was carried out to investigate the impact of Cd and Zn extractability in soil and speciation in pore water of industrial contaminated soils, on metal concentration in a metal sensitive species like spinach (Spinacia oleracea) and a more metal tolerant species like Italian ryegrass (Lolium multiflorum). For chemical speciation of Cd and Zn in pore water, WHAM\\/Model

sgeir R. Alms; Peder Lombns; Trine A. Sogn; Jan Mulder

2006-01-01

238

Full subunit coverage liquid chromatography electrospray ionization mass spectrometry (LCMS+) of an oligomeric membrane protein: cytochrome b(6)f complex from spinach and the cyanobacterium Mastigocladus laminosus.  

PubMed

Highly active cytochrome b(6)f complexes from spinach and the cyanobacterium Mastigocladus laminosus have been analyzed by liquid chromatography with electrospray ionization mass spectrometry (LCMS+). Both size-exclusion and reverse-phase separations were used to separate protein subunits allowing measurement of their molecular masses to an accuracy exceeding 0.01% (+/-3 Da at 30,000 Da). The products of petA, petB, petC, petD, petG, petL, petM, and petN were detected in complexes from both spinach and M. laminosus, while the spinach complex also contained ferredoxin-NADP(+) oxidoreductase (Zhang, H., Whitelegge, J. P., and Cramer, W. A. (2001) Flavonucleotide:ferredoxin reductase is a subunit of the plant cytochrome b(6)f complex. J. Biol. Chem. 276, 38159-38165). While the measured masses of PetC and PetD (18935.8 and 17311.8 Da, respectively) from spinach are consistent with the published primary structure, the measured masses of cytochrome f (31934.7 Da, PetA) and cytochrome b (24886.9 Da, PetB) modestly deviate from values calculated based upon genomic sequence and known post-translational modifications. The low molecular weight protein subunits have been sequenced using tandem mass spectrometry (MSMS) without prior cleavage. Sequences derived from the MSMS spectra of these intact membrane proteins in the range of 3.2-4.2 kDa were compared with translations of genomic DNA sequence where available. Products of the spinach chloroplast genome, PetG, PetL, and PetN, all retained their initiating formylmethionine, while the nuclear encoded PetM was cleaved after import from the cytoplasm. While the sequences of PetG and PetN revealed no discrepancy with translations of the spinach chloroplast genome, Phe was detected at position 2 of PetL. The spinach chloroplast genome reports a codon for Ser at position 2 implying the presence of a DNA sequencing error or a previously undiscovered RNA editing event. Clearly, complete annotation of genomic data requires detailed expression measurements of primary structure by mass spectrometry. Full subunit coverage of an oligomeric intrinsic membrane protein complex by LCMS+ presents a new facet to intact mass proteomics. PMID:12438564

Whitelegge, Julian P; Zhang, Huamin; Aguilera, Rodrigo; Taylor, Ross M; Cramer, William A

2002-10-01

239

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...

240

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...

241

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2011 CFR

...degree of maturity, more open leaf structure in relation to the B Group...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in...

2011-01-01

242

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2012 CFR

...degree of maturity, more open leaf structure in relation to the B Group...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in...

2012-01-01

243

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2013 CFR

...degree of maturity, more open leaf structure in relation to the B Group...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in...

2013-01-01

244

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2014 CFR

...degree of maturity, more open leaf structure in relation to the B Group...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in oil...Orange Smoking Leaf Mellow, open leaf structure, medium body, lean in...

2014-01-01

245

Leaf hydraulics II: vascularized tissues.  

PubMed

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

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

2014-01-01

246

Mathematical modeling and numerical analysis of the growth of non-O157 Shiga toxin-producing Escherichia coli in spinach leaves.  

PubMed

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 studies conducted isothermally at 4, 8, 15, 20, 25, 30, and 35 C. Both STEC and background microflora were enumerated to develop kinetic models. Growth of STEC in spinach leaves was observed at elevated temperatures (15-35 C), but not at 4 and 8 C. This study considered the dynamic interactions between the STEC cells and the background microflora. A modified Lotka-Volterra and logistic equation was used to simulate the bacterial growth. In combination with an unconstrained optimization procedure, the differential growth equations were solved numerically to evaluate the dynamic interactions between the STEC cells and the background microflora, and to determine the kinetic parameters by fitting each growth curve to the growth equations. A close agreement between the experimental growth curves and the numerical analysis results was obtained. The analytical results showed that the growth of STEC in spinach leaves was unhindered when the population was low, but the growth was suppressed by the background microflora as the STEC population approached the maximum population density. The effect of temperature on the growth of both STEC and background microflora was also evaluated. Secondary models, evaluating the effect of temperature on growth rates, were also developed. The estimated apparent minimum growth temperature for STEC was 11 C in commercial spinach leaves. The methodology and results of this study can be used to examine the dynamic interactions and growth between different bacteria in foods, and to conduct risk assessments of STEC in spinach leaves. PMID:23141643

Huang, Lihan

2012-11-01

247

Respiration of sugars in spinach (Spinacia oleraces), maize (Zea mays), and Chlamydomonas reinhardtii F-60 chloroplasts with emphasis on the hexose kinases  

SciTech Connect

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.

Singh, K.K.; Chen, C.; Epstein, D.K.; Gibbs, M. (Brandeis Univ., Waltham, MA (United States))

1993-06-01

248

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

NASA Astrophysics Data System (ADS)

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.

Xue, Lihong; Yang, Linzhang

249

Over-expression of an arabidopsis family A sucrose phosphate synthase (SPS) gene alters plant growth and fibre development  

Microsoft Academic Search

The objective of this study was to manipulate the intracellular pools of sucrose by differentially expressing exogenous sucrose\\u000a phosphate synthase (SPS) and investigating its role in regulating plant growth and fibre development. Tobacco (Nicotiana tabacum cv. Xanthi) plants were transformed with an arabidopsis SPS gene under the regulation of the ubiquitously expressed tandem\\u000a repeat of the 35S cauliflower mosaic virus

Ji-Young Park; Thomas Canam; Kyu-Young Kang; David D. Ellis; Shawn D. Mansfield

2008-01-01

250

Diffuse and specular characteristics of leaf reflectance  

NASA Technical Reports Server (NTRS)

In this paper, the evolution of current understanding of the mechanisms of leaf reflectance is reviewed. The use of measurements of polarized reflectance to separate leaf reflectance into diffuse and specular components is discussed. A section on the factors influencing leaf reflectance - leaf structure and physiological disturbances - is included along with discussion on the manner in which these influences are manifested.

Grant, Lois

1987-01-01

251

Experiments in Whole Leaf Photosynthesis  

ERIC Educational Resources Information Center

Described is a simple experimental system, which uses radioactive carbon dioxide to study whole leaf photosynthesis under a variety of conditions. Other experiments and simple apparatus for the experiments are also described. (Author/RH)

Stewart, J. C.; And Others

1974-01-01

252

Near infrared leaf reflectance modeling  

NASA Technical Reports Server (NTRS)

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

Parrish, J. B.

1985-01-01

253

Stem-and-Leaf Plots  

NSDL National Science Digital Library

This lesson is designed to introduce students to stem-and-leaf plots as a graphical way to represent a data set. The lesson also reviews measures of central tendency. This lesson provides links to discussions and activities related to stem-and-leaf plots as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one.

2010-01-01

254

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

Microsoft Academic Search

Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf\\u000a dark respiration rate (R\\u000a d) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic\\u000a capacity (A\\u000a max). However, it is not known whether such scaling, if it exists, is similar among

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

1998-01-01

255

Bacteriophages Reduce Experimental Contamination of Hard Surfaces, Tomato, Spinach, Broccoli, and Ground Beef by Escherichia coli O157:H7?  

PubMed Central

A bacteriophage cocktail (designated ECP-100) containing three Myoviridae phages lytic for Escherichia coli O157:H7 was examined for its ability to reduce experimental contamination of hard surfaces (glass coverslips and gypsum boards), tomato, spinach, broccoli, and ground beef by three virulent strains of the bacterium. The hard surfaces and foods contaminated by a mixture of three E. coli O157:H7 strains were treated with ECP-100 (test samples) or sterile phosphate-buffered saline buffer (control samples), and the efficacy of phage treatment was evaluated by comparing the number of viable E. coli organisms recovered from the test and control samples. Treatments (5 min) with the ECP-100 preparation containing three different concentrations of phages (1010, 109, and 108 PFU/ml) resulted in statistically significant reductions (P = <0.05) of 99.99%, 98%, and 94%, respectively, in the number of E. coli O157:H7 organisms recovered from the glass coverslips. Similar treatments resulted in reductions of 100%, 95%, and 85%, respectively, in the number of E. coli O157:H7 organisms recovered from the gypsum board surfaces; the reductions caused by the two most concentrated phage preparations were statistically significant. Treatment with the least concentrated preparation that elicited significantly less contamination of the hard surfaces (i.e., 109 PFU/ml) also significantly reduced the number of viable E. coli O157:H7 organisms on the four food samples. The observed reductions ranged from 94% (at 120 4 h posttreatment of tomato samples) to 100% (at 24 4 h posttreatment of spinach samples). The data suggest that naturally occurring bacteriophages may be useful for reducing contamination of various hard surfaces, fruits, vegetables, and ground beef by E. coli O157:H7. PMID:18723643

Abuladze, Tamar; Li, Manrong; Menetrez, Marc Y.; Dean, Timothy; Senecal, Andre; Sulakvelidze, Alexander

2008-01-01

256

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

SciTech Connect

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.

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

1990-01-01

257

Perspectives on leaf dorsoventral polarity.  

PubMed

Leaves occur in a vast array of shapes and sizes, with complex diversity contributing to optimization of the principal function of photosynthesis. The program of development from a self-renewing stem cell population to a mature leaf has been of interest to biologists for years. Many genes involved in this process have been identified, particularly in the model eudicot Arabidopsis, so that now we have a greater understanding of mechanisms of stem cell maintenance, cell differentiation and organogenesis. One aspect of leaf development that is of particular interest is the establishment of dorsoventral polarity: the distinct adaxial (upper) and abaxial (lower) sides of the leaf. Early studies postulated conceptual models of how establishment of polarity leads to the development of planar leaves. Studies over the past decade have defined genetic details of this model, and uncovered diverse mechanisms of gene regulation that facilitate development of leaf dorsoventral polarity, including transcriptional regulation, chromatin modification, DNA modification, regulation by short RNAs and translational and post-translational regulation. This review will discuss these regulatory mechanisms in the context of leaf dorsoventrality, and will conclude with unresolved questions and areas of future research. PMID:20369373

Szakonyi, Dra; Moschopoulos, Alexis; Byrne, Mary E

2010-05-01

258

Inactivation of ribulosebisphosphate carboxylase/oxygenase from Rhodospirillum rubrum and spinach with the new affinity label 2-bromo-1,5-dihydroxy-3-pentanone 1,5-bisphosphate  

SciTech Connect

In an attempt to identify the active-site base believed to initiate catalysis by ribulosebisphosphate carboxylase, we have synthesized 2-bromo-1, 5-dihydroxy-3-pentanone 1,5-bisphosphate, a reactive analogue of a postulated intermediate of carboxylation. Although highly unstable, this compound can be shown to inactivate the carboxylases from both Rhodospirillum rubrum and spinach rapidly and irreversibly. Inactivation follows pseudo first-order kinetics, shows rate saturation and is greatly reduced by saturating amounts of the competitive inhibitor, 2-carboxyribitol 1,5-bisphosphate. The incorporation of reagent, quantified by reducing the modified carboxylases with (/sup 3/H)NaBH/sub 4/, shows that inactivation results from the modification of approximately one residue per catalytic subunit of the Rhodospirillum rubrum enzyme and less than one residue per protomeric unit of the spinach enzyme.

Donnelly, M.I. (Univ. of Tennessee, Oak Ridge); Hartman, F.C.

1981-11-16

259

Chloroplastic ascorbate peroxidase is the primary target of methylviologen-induced photooxidative stress in spinach leaves: its relevance to monodehydroascorbate radical detected with in vivo ESR  

Microsoft Academic Search

Methylviologen (MV) induces oxidative damages in leaves. In order to understand its mechanism we studied initial biochemical events under light in MV-fed spinach leaves. When isolated chloroplasts were illuminated in the presence of MV, both stromal and thylakoid-bound ascorbate peroxidases (APX) were inactivated rapidly at the same rates, and their inactivation was retarded by ascorbate (AsA) at higher concentrations. Since

Junichi Mano; Chiaki Ohno; Yoshinori Domae; Kozi Asada

2001-01-01

260

Characterization of the spinach chloroplast genes for the S4 ribosomal protein, tRNAThr (UGU) and tRNASer (GGA)  

Microsoft Academic Search

The map location and nucleotide sequence of the genes for the S4 ribosomal protein (rps4) and for tRNAThr (UGU) (trnT) and tRNASer (GGA) (trnS) on spinach chloroplast DNA have been determined. rps4 lies approximately 5 kb 3' to atpBE in the large single copy region and is transcribed in the same direction as atpBE. It has a 178 bp leader

S. Ben Tahar; W. Bottomley; P. R. Whitfeld

1986-01-01

261

Evaluation of Models Describing the Growth of Nalidixic Acid-Resistant E. coli O157:H7 in Blanched Spinach and Iceberg Lettuce as a Function of Temperature  

PubMed Central

The aim of this study was to model the growth of nalidixic acid-resistant E. coli O157:H7 (E. coli O157:H7NR) in blanched spinach and to evaluate model performance with an independent set of data for interpolation (8.5, 13, 15 and 27 C) and for extrapolation (broth and fresh-cut iceberg lettuce) using the ratio method and the acceptable prediction zone method. The lag time (LT), specific growth rate (SGR) and maximum population density (MPD) obtained from each primary model were modeled as a function of temperature (7, 10, 17, 24, 30, and 36 C) using Davey, square root, and polynomial models, respectively. At 7 C, the populations of E. coli O157:H7NR increased in tryptic soy broth with nalidixic acid (TSBN), blanched spinach and fresh-cut iceberg lettuce, while the populations of E. coli O157:H7 decreased in TSB after 118 h of LT, indicating the risk of nalidixic acid-resistant strain of E. coli O157:H7 contaminated in ready-to-eat produce at refrigerated temperature. When the LT and SGR models of blanched spinach was extended to iceberg lettuce, all relative errors (percentage of RE = 100%) were inside the acceptable prediction zone and had an acceptable Bf and Af values. Thus, it was concluded that developed secondary models for E. coli O157:H7NR in blanched spinach were suitable for use in making predictions for fresh cut iceberg lettuce, but not for static TSBN in this work. PMID:23839062

Kim, Juhui; Chung, Hyunjung; Cho, Joonil; Yoon, Kisun

2013-01-01

262

Inactivation of ribulosebisphosphate carboxylase\\/oxygenase from Rhodospirillum rubrum and spinach with the new affinity label 2-bromo-1,5-dihydroxy-3-pentanone 1,5-bisphosphate  

Microsoft Academic Search

In an attempt to identify the active-site base believed to initiate catalysis by ribulosebisphosphate carboxylase, we have synthesized 2-bromo-1, 5-dihydroxy-3-pentanone 1,5-bisphosphate, a reactive analogue of a postulated intermediate of carboxylation. Although highly unstable, this compound can be shown to inactivate the carboxylases from both Rhodospirillum rubrum and spinach rapidly and irreversibly. Inactivation follows pseudo first-order kinetics, shows rate saturation and

M. I. Donnelly; F. C. Hartman

1981-01-01

263

Life in the Leaf Litter  

NSDL National Science Digital Library

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

264

Estimating leaf biochemistry using the PROSPECT leaf optical properties model  

Microsoft Academic Search

The biophysical, biochemical, and optical properties of 63 fresh leaves and 58 dry leaves were measured to investigate the potential of remote sensing to estimate the leaf biochemistry from space. Almost 2000 hemispherical reflectance and transmittance spectra were acquired from 400 nm to 2500 nm using a laboratory spectrophotometer. The amount of chlorophyll, water, protein, cellulose, hemicellulose, lignin, and starch

S. Jacquemoud; S. L. Ustin; J. Verdebout; G. Schmuck; G. Andreoli; B. Hosgood

1996-01-01

265

7 CFR 29.3525 - Leaf.  

Code of Federal Regulations, 2010 CFR

...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) 29.3525 Leaf. Whole, unstemmed leaf....

2010-01-01

266

7 CFR 29.3525 - Leaf.  

Code of Federal Regulations, 2011 CFR

...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) 29.3525 Leaf. Whole, unstemmed leaf....

2011-01-01

267

7 CFR 29.3647 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2012 CFR

...Leaf. Ripe medium body, open leaf structure, smooth, rich in oil, clear... Ripe, medium body, open leaf structure, smooth, rich in oil, clear... Mature, medium body, firm leaf structure, crepy, oily, normal...

2012-01-01

268

Leaf element concentrations of terrestrial plants across China are  

E-print Network

with leaf elements responsible for cell structure and enzymes. Main conclusions Leaf element concentrationsRESEARCH PAPER Leaf element concentrations of terrestrial plants across China are influenced cycles of terrestrial eco- systems are strongly affected by leaf element concentrations. Understanding

Slik, Ferry

269

7 CFR 29.3647 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2014 CFR

...Leaf. Ripe medium body, open leaf structure, smooth, rich in oil, clear... Ripe, medium body, open leaf structure, smooth, rich in oil, clear... Mature, medium body, firm leaf structure, crepy, oily, normal...

2014-01-01

270

7 CFR 29.3647 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...Leaf. Ripe medium body, open leaf structure, smooth, rich in oil, clear... Ripe, medium body, open leaf structure, smooth, rich in oil, clear... Mature, medium body, firm leaf structure, crepy, oily, normal...

2010-01-01

271

7 CFR 29.3647 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2011 CFR

...Leaf. Ripe medium body, open leaf structure, smooth, rich in oil, clear... Ripe, medium body, open leaf structure, smooth, rich in oil, clear... Mature, medium body, firm leaf structure, crepy, oily, normal...

2011-01-01

272

7 CFR 29.3647 - Heavy Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

...Leaf. Ripe medium body, open leaf structure, smooth, rich in oil, clear... Ripe, medium body, open leaf structure, smooth, rich in oil, clear... Mature, medium body, firm leaf structure, crepy, oily, normal...

2013-01-01

273

Influence of different planting seasons of six leaf vegetables on residues of five pesticides.  

PubMed

To investigate the influence of different planting seasons on the dissipation of pesticides, field experiments of thiophanate-methyl, metalaxyl, fluazifop-P-butyl, chlorpyrifos, and ?-cyhalothrin on six crops including pakchoi, rape, crown daisy, amaranth, spinach, and lettuce were designed and conducted. In this study, a high-performance liquid chromatography and electrospray ionization-tandem mass spectrometer with multiple reaction monitoring was used to simultaneously determine thiophanate-methyl and its metabolite carbendazim, metalaxyl, and fluazifop-P-butyl in various samples; gas chromatography with an electron capture detector was used to detect chlorpyrifos and ?-cyhalothrin. The limits of quantitation (LOQs) of these six pesticides were in the range of 0.001-0.01 mg kg(-1) for all samples, and the average recoveries of all pesticides ranged from 60.1 to 119.1% at 0.01 and 0.1 mg kg(-1) spiked levels. The relative standard deviation (RSD) ranged from 1.1 to 13.9%. All maximal concentrations of the six pesticides in six leaf vegetables in autumn were higher than in summer in Beijing. For most pesticides half-lives in autumn were longer than in summer. The results showed that the initial concentration, maximal concentration, and half-lives of pesticides were influenced not only by environmental factors such as light, heat, moisture, and rainy climate but also by plant matrices. PMID:23978278

Fan, Sufang; Deng, Kailin; Yu, Chuanshan; Zhao, Pengyue; Bai, Aijuan; Li, Yanjie; Pan, Canping; Li, Xuesheng

2013-09-25

274

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

PubMed

A technique is described for the separation of mesophyll and bundle sheath cells from Digitaria sanguinalis leaves and evidence for separation is given with light and scanning electron micrographs. Gentle grinding of fully differentiated leaves in a mortar releases mesophyll cells which are isolated on nylon nets by filtration. More extensive grinding of the remaining tissue yields bundle sheath strands which are isolated by filtration with stainless steel sieves and nylon nets. Further grinding of bundle sheath strands in a tissue homogenizer releases bundle sheath cells which are collected on nylon nets. Percentage of purity derived from cell counts and yield data on a chlorophyll basis are given.The internal leaf cell morphology is presented in scanning electron micrographs and compared with light micrographs of fully-differentiated D. sanguinalis leaves. In leaves of plants which possess the C(4)-dicarboxylic acid cycle of photosynthesis, the relationship of leaf morphology to photosynthesis in mesophyll and bundle sheath cells is considered, and the hypothesis is presented that as atmospheric CO(2) enters a leaf about 85% is fixed by the C(4)-dicarboxylic acid cycle in the mesophyll cells and 10 to 15% is fixed by the reductive pentose phosphate cycle in the bundle sheath cells.A technique also is given for the isolation of mesophyll cells from spinach leaves. PMID:16657571

Edwards, G E; Black, C C

1971-01-01

275

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

E-print Network

in support and structure. Some have proposed that mechanical support and dry mass investments per unit leafThe scaling of leaf area and mass: the cost of light interception increases with leaf size Rube (specific leaf area, SLA) is a key trait from physiological, ecological and biophysical perspectives

Minnesota, University of

276

Leaf respiration is differentially affected by leaf vs. stand-level night-time warming  

E-print Network

to temperature with the temperature coefficient of the reaction or Q10 (change in the rate of a reaction rate with a 10 C increase in leaf temperature) was 1.7 when the leaf temperature was manipulatedLeaf respiration is differentially affected by leaf vs. stand-level night-time warming K E V I N L

Saleska, Scott

277

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 ...

278

Leaf Photosynthesis Under Drought Stress  

Microsoft Academic Search

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

Gabriel Cornic; Angelo Massacci

279

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 ...

280

Original article Photosynthesis, leaf area and productivity  

E-print Network

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

Paris-Sud XI, Université de

281

ZONATE LEAF SPOT (CAUSED BY CRISTULARIELLA MORICOLA)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Zonate leaf spot derives it name from the occurrence of large, circular leaf lesions with distinct concentric rings. Initially the leaf lesions are light tan in color and the concentric rings are symmetrical appearing as a bulls eye. Initial lesions are 5-10 mm in diameter and continue to expand...

282

Tree Branch Angle: Maximizing Effective Leaf Area  

Microsoft Academic Search

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

Hisao Honda; Jack B. Fisher

1978-01-01

283

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture...37 and Foreign Type 95) 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2012-01-01

284

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture...14 and Foreign Type 92) 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2010-01-01

285

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2013-01-01

286

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2011-01-01

287

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture...14 and Foreign Type 92) 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2011-01-01

288

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture...Type 31 and Foreign Type 93) 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or...

2012-01-01

289

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture...37 and Foreign Type 95) 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2011-01-01

290

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture...Tobacco (u.s. Type 21) 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2011-01-01

291

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture...Type 31 and Foreign Type 93) 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or...

2014-01-01

292

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture...Type 31 and Foreign Type 93) 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or...

2011-01-01

293

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture...37 and Foreign Type 95) 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2010-01-01

294

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2014-01-01

295

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture...14 and Foreign Type 92) 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2013-01-01

296

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

297

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture...37 and Foreign Type 95) 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2013-01-01

298

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

299

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture...14 and Foreign Type 92) 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2014-01-01

300

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf structure. 29.1030 Section 29.1030 Agriculture...14 and Foreign Type 92) 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2012-01-01

301

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture...Type 31 and Foreign Type 93) 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or...

2010-01-01

302

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture...Tobacco (u.s. Type 21) 29.2278 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2010-01-01

303

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf structure. 29.3527 Section 29.3527 Agriculture...37 and Foreign Type 95) 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2014-01-01

304

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2012-01-01

305

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf structure. 29.3035 Section 29.3035 Agriculture...Type 31 and Foreign Type 93) 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or...

2013-01-01

306

Tansley review Leaf venation: structure, function,  

E-print Network

Tansley review Leaf venation: structure, function, development, evolution, ecology and applications, CA 90095, USA Contents Summary 983 I. Introduction 983 II. Overall structure of the leaf venation 983,agricultureandtechnology.Wesynthesizeclassicalconceptsandtherecentliteratureona wide range of aspects of leaf venation. We describe 10 major structural features that contribute

Sack, Lawren

307

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf structure. 29.2530 Section 29.2530 Agriculture...23, and Foreign Type 96) 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See...

2010-01-01

308

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

309

Bean leaf beetle management in soybean  

E-print Network

Bean leaf beetle management in soybean Erin W. Hodgson Department of Entomology Iowa State concerned about BPMV #12;Bean leaf beetle threshold for 1st generation adults (per 20 sweeps) Control $7 $8 for bivoltine or multivoltine regions · Use counts to help manage 2nd/3rd generations #12;Bean leaf beetle

Jurenka, Russell A.

310

Bean leaf beetle biology in soybean  

E-print Network

Bean leaf beetle biology in soybean Erin W. Hodgson Department of Entomology Iowa State University September 2009 #12;Outline · Description · Life cycle · Biology · Damage #12;Bean leaf beetle (BLB) · Cerotoma trifurcata ­ leaf beetle (Coleoptera: Chrysomelidae) · 5 mm long, oval shape · Typically dark

Jurenka, Russell A.

311

CORN LEAF CHLOROPHYLL STATUS FROM HYPERSPECTRAL IMAGES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Leaf chlorophyll concentration is an indicator of plant N status. Subtle differences in canopy reflectance due to changes in leaf chlorophyll concentration are often overwhelmed by the large changes in reflectance associated with soil brightness and leaf area index (LAI). Our objective was to devel...

312

Modeling and visualization of leaf venation patterns  

Microsoft Academic Search

We introduce a class of biologically-motivated algorithms for generating leaf venation patterns. These algorithms simulate the interplay between three processes: (1) development of veins towards hormone (auxin) sources embedded in the leaf blade; (2) modification of the hormone source distribution by the proximity of veins; and (3) modification of both the vein pattern and source distribution by leaf growth. These

Adam Runions; Martin Fuhrer; Pavol Federl; Anne-Galle Rolland-Lagan; Przemyslaw Prusinkiewicz

2005-01-01

313

7 CFR 29.3528 - Leaf surface.  

Code of Federal Regulations, 2014 CFR

...TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign...3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

2014-01-01

314

7 CFR 29.3528 - Leaf surface.  

Code of Federal Regulations, 2011 CFR

...TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign...3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

2011-01-01

315

7 CFR 29.3528 - Leaf surface.  

Code of Federal Regulations, 2012 CFR

...TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign...3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

2012-01-01

316

7 CFR 29.3528 - Leaf surface.  

Code of Federal Regulations, 2013 CFR

...TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign...3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

2013-01-01

317

7 CFR 29.3528 - Leaf surface.  

Code of Federal Regulations, 2010 CFR

...TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign...3528 Leaf surface. The roughness or smoothness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

2010-01-01

318

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2012 CFR

...and Tolerances B1LChoice Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 5 percent. B2LFine Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 10 percent. B3LGood Quality Lemon Leaf Ripe, firm leaf...

2012-01-01

319

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2014 CFR

...and Tolerances B1LChoice Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 5 percent. B2LFine Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 10 percent. B3LGood Quality Lemon Leaf Ripe, firm leaf...

2014-01-01

320

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2011 CFR

...and Tolerances B1LChoice Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 5 percent. B2LFine Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 10 percent. B3LGood Quality Lemon Leaf Ripe, firm leaf...

2011-01-01

321

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

...and Tolerances B1LChoice Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 5 percent. B2LFine Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 10 percent. B3LGood Quality Lemon Leaf Ripe, firm leaf...

2013-01-01

322

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...and Tolerances B1LChoice Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 5 percent. B2LFine Quality Lemon Leaf Ripe, firm leaf structure...tolerance, 10 percent. B3LGood Quality Lemon Leaf Ripe, firm leaf...

2010-01-01

323

Leaf area dynamics of conifer forests  

SciTech Connect

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.

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

1995-07-01

324

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

325

Rapid, enhanced detection of Salmonella Typhimurium on fresh spinach leaves using micron-scale, phage-coated magnetoelastic biosensors  

NASA Astrophysics Data System (ADS)

In order to cost-effectively and rapidly detect bacterial food contamination in the field, the potential usefulness of phage-coated magnetoelastic (ME) biosensors has been recently reported. These biosensors are freestanding, mass-sensitive biosensors that can be easily batch-fabricated, thereby reducing the fabrication cost per sensor to a fraction of a cent. In addition, the biosensors can be directly placed on fresh produce surfaces and used to rapidly monitor possible bacterial food contamination without any preceding sample preparation. Previous investigations showed that the limit of detection (LOD) with millimeter-scale ME biosensors was fairly low for fresh produce with smooth surfaces (e.g., tomatoes and shell eggs). However, the LOD is anticipated to be dependent on the size of the biosensors as well as the topography of produce surfaces of interest. This paper presents an investigation into the use of micron-scale, phage-coated ME biosensors for the enhanced detection of Salmonella Typhimurium on fresh spinach leaves.

Horikawa, Shin; Vaglenov, Kiril A.; Gerken, Dana M.; Chai, Yating; Park, Mi-Kyung; Li, Suiqiong; Petrenko, Valery A.; Chin, Bryan A.

2012-05-01

326

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

PubMed Central

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

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

2014-01-01

327

Comparison of the levels of six endogenous gibberellins in roots and shoots of spinach in relation to photoperiod  

SciTech Connect

This communication describes the distribution of gibberellins (GAs) in roots and shoots of spinach in relation to photoperiod. From previous work shoots were known to contain GA/sub 53/, GA/sub 44/, GA/sub 19/, GA/sub 17/, GA/sub 20/, and GA/sub 29/. We now show by combined gas chromatography-mass spectrometry that roots contain gas chromatography-selected ion current monitoring. Neither GA/sub 17/ nor GA/sub 20/ were detected in root extracts. Analysis by the d-5 corn bioassay also showed no effect of photoperiodic treatment on the levels of GA-like substances in root extracts. Both phloem and xylem exudates had patterns of GA-like activity similar to those found in shoots and roots, respectively. Moreover, foliar application of (/sup 3/H)GA/sub 20/ resulted in the transport of label from the shoot to the roots. Over half of the label in the roots represented unmetabolized (/sup 3/H)GA/sub 20/, indicating that part of the GA/sub 20/ in the phloem is transported to the roots. Consequently, if GA/sub 20/ is made in, or transported to the roots, it is rapidly metabolized in that organ. This is a clear indication that regulation of GA metabolism is greatly different in roots and shoots.

Metzger, J.D.; Zeevaart, J.A.D.

1980-10-01

328

Structure and expression of the nuclear gene coding for the plastid CS1 ribosomal protein from spinach.  

PubMed

The chloroplast ribosomal protein CS1 is an essential component of the plastids translational machinery involved in translation initiation. Southern analysis suggests that the corresponding nuclear gene is present in one copy in the spinach genome. We have isolated and sequenced the gene (rps1) to study its expression at the transcriptional level. The gene consists of 7 exons and 6 introns including an unusually large intron in the 5' coding region. No canonical TATA-box is found in the 5' upstream region of the gene. rps1 transcripts are detected early during germination and a significant accumulation is observed after the protrusion of the radicle. CS1 mRNAs are present in all organs of young seedlings although there are dramatic differences in the steady state level of the mRNAs between leaves and roots tissues. Transcripts accumulate independently of the presence or absence of light. Band shift analysis shows that the +1, -400 bp region of the gene can bind different sets of proteins isolated from roots and leaves nuclei. We suggest that the expression of the housekeeping plastid-related rps1 gene is regulated in a tissue-specific manner by transcriptional trans-acting factors. PMID:1508710

Franzetti, B; Zhou, D X; Mache, R

1992-08-25

329

A fluorescence detected magnetic resonance investigation of the carotenoid triplet states associated with photosystem II of isolated spinach thylakoid membranes.  

PubMed

The carotenoid triplet populations associated with the fluorescence emission chlorophyll forms of Photosystem II have been investigated in isolated spinach thylakoid membranes by means of fluorescence detected magnetic resonance in zero field (FDMR). The spectra collected in the 680-690 nm emission range, have been fitted by a global analysis procedure. At least five different carotenoid triplet states coupled to the terminal emitting chlorophyll forms of PS II, peaking at 682 nm, 687 nm and 692 nm, have been characterised. The triplets associated with the outer antenna emission forms, at 682 nm, have zero field splitting parameters |D| = 0.0385 cm-1, |E| = 0.00367 cm-1; |D| = 0.0404 cm-1, |E| = 0.00379 cm-1 and |D| = 0.0386 cm-1, |E| = 0.00406 cm-1 which are very similar to those previously reported for the xanthophylls of the isolated LHC II complex. Therefore the FDMR spectra recorded in this work provide insights into the organisation of the LHC II complex in the unperturbed environment represented by thylakoid membranes. The additional carotenoid triplet populations, detected by monitoring the chlorophyll emission at 687 and 692 nm, are assigned to carotenoids bound to inner antenna complexes and hence attributed to beta-carotene molecules. PMID:16172946

Santabarbara, Stefano; Agostini, Giancarlo; Heathcote, Peter; Carbonera, Donatella

2005-11-01

330

Dynamics of the antioxidant system during seed osmopriming, post-priming germination, and seedling establishment in Spinach (Spinacia oleracea).  

PubMed

Osmopriming is a pre-sowing treatment that improves seed germination performance and stress tolerance. To understand osmopriming physiology, and its association with post-priming stress tolerance, we investigated the antioxidant system dynamics during three stages: during osmopriming, post-priming germination, and seedling establishment. Spinach seeds (Spinacia oleracea L. cv. Bloomsdale) were primed with -0.6 MPa PEG at 15C for 8 d, and dried at room temperature for 2 d. Unprimed and primed germinating seeds/seedlings were subjected to a chilling and desiccation stresses. Seed/seedling samples were collected for antioxidant assays and germination performance and stress tolerance were evaluated. Our data indicate that: (1) during osmopriming the transition of seeds from dry to germinating state represses the antioxidant pathways (residing in dry seeds) that involve CAT and SOD enzymes but stimulates another pathway (only detectable in imbibed seeds) involving APX; (2) a renewal of antioxidant system, possibly required by seedling establishment, occurs after roughly 5 d of germination; (3) osmopriming strengthens the antioxidant system and increases seed germination potential, resulting in an increased stress tolerance in germinating seeds. Osmopriming-mediated promotive effect on stress tolerance, however, may diminish in relatively older (e.g. ~5-week) seedlings. PMID:21421363

Chen, Keting; Arora, Rajeev

2011-02-01

331

Habitat Complexity of Stream Leaf Packs: Effects on Benthic Macroinvertebrates and Leaf Litter Breakdown  

NASA Astrophysics Data System (ADS)

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.

Ruetz, C. R.; Vanhaitsma, D. L.; Breen, M. J.

2005-05-01

332

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

PubMed Central

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

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

2014-01-01

333

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

PubMed Central

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

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

2015-01-01

334

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

PubMed

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

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

2015-02-01

335

Salinity effects on leaf anatomy  

Microsoft Academic Search

Increasing salinity led to substantially higher ratios of mesophyll surface area to leaf area (A\\/sup mes\\/\\/A) for Phaseolus vulgaris and Gossypium hirsutum and a smaller increase for Atriplex patula, a salt-tolerant species. The increase in internal surface for CO absorption did not lead to higher CO uptake rates, since the CO resistance expressed on the basis of mesophyll cell wall

D. J. Longstreth; P. S. Nobel

1979-01-01

336

Leaf drop affects herbivory in oaks.  

PubMed

Leaf phenology is important to herbivores, but the timing and extent of leaf drop has not played an important role in our understanding of herbivore interactions with deciduous plants. Using phylogenetic general least squares regression, we compared the phenology of leaves of 55 oak species in a common garden with the abundance of leaf miners on those trees. Mine abundance was highest on trees with an intermediate leaf retention index, i.e. trees that lost most, but not all, of their leaves for 2-3 months. The leaves of more evergreen species were more heavily sclerotized, and sclerotized leaves accumulated fewer mines in the summer. Leaves of more deciduous species also accumulated fewer mines in the summer, and this was consistent with the idea that trees reduce overwintering herbivores by shedding leaves. Trees with a later leaf set and slower leaf maturation accumulated fewer herbivores. We propose that both leaf drop and early leaf phenology strongly affect herbivore abundance and select for differences in plant defense. Leaf drop may allow trees to dispose of their herbivores so that the herbivores must recolonize in spring, but trees with the longest leaf retention also have the greatest direct defenses against herbivores. PMID:23774946

Pearse, Ian S; Karban, Richard

2013-11-01

337

Farm management, environment, and weather factors jointly affect the probability of spinach contamination by generic Escherichia coli at the preharvest stage.  

PubMed

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

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

2014-04-01

338

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

PubMed Central

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

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

2014-01-01

339

Biosensor for selective detection of E. coli in spinach using the strong affinity of derivatized mannose with fimbrial lectin.  

PubMed

Escherichia coli (E. coli) contamination in foods and water resources represents a major threat for human health and the environment. This work exploits the strong affinity of mannose-containing oligosaccharides with the fimbrial lectin of E. coli to design novel biosensors. Modified carbohydrate ligands were synthesized by introducing phenyl residues and aliphatic chains to mannose via reductive amination in order to increase both the affinity and selectivity to E. coli compared to other pathogenic bacteria. The synthesized ligands include p-thiolphenyl aminomannose (PTAM), p-carboxyphenyl aminomannose (PCAM), 1-deoxy-1-aminomannopyranoside (DAMP), glucosamine and low molecular weight chitosan bonded to mercapto undecanoic acid. The structures of the ligands were confirmed using (1)H NMR and 1H, (13)C, COZY NMR, and ESI/MS. The ligands were immobilized onto gold electrodes and SPR surfaces using-mercaptoundecanoic acid with glycine as deactivating agent. Two detection mechanisms were tested: (i) metal-enhanced electrochemical detection (MED) and (ii) label-free surface plasmon resonance (SPR) detection. The introduction of phenyl residues and aliphatic side groups to the mannose-containing oligosaccharides produced extremely high affinity for E. coli with detection limit of 1 cfu/mL. The relative selectivity of these ligands for E. coli, Citrobacter freundii, Staphylococcus epidermidis were 100%, 2.6% and 8.6% respectively. The biosensors were validated using spinach leaves at 3.0 cfu/mL. The work provides a generic biosensor for other pathogenic bacteria by enabling multivalent binding, immediate recognition for pathogens as well as inhibition of bacterial growth. PMID:24906084

Yazgan, Idris; Noah, Naumih M; Toure, Ousmane; Zhang, Siyi; Sadik, Omowunmi A

2014-11-15

340

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

PubMed Central

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

Kimata-Ariga, Yoko; Hase, Toshiharu

2014-01-01

341

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

SciTech Connect

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

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

1996-09-03

342

Yield and leaf blade area comparisons of extra leafy to normal leafed maize (Zea mays L.)  

E-print Network

Inadequate information is available concerning the yield performance of maize (Zea mays L.) cultivars with genotypes of greater than normal leaf areas. Such genotypes are called Extra-leafy or Leafy cultivars and have greater leaf production above...

Rushing, Ronald Wayne

1996-01-01

343

Compound leaf development in model plant species.  

PubMed

Plant leaves develop in accordance with a common basic program, which is flexibly adjusted to the species, developmental stage and environment. Two key stages of leaf development are morphogenesis and differentiation. In the case of compound leaves, the morphogenesis stage is prolonged as compared to simple leaves, allowing for the initiation of leaflets. Here, we review recent advances in the understanding of how plant hormones and transcriptional regulators modulate compound leaf development, yielding a substantial diversity of leaf forms, focusing on four model compound leaf organisms: cardamine (Cardamine hirsuta), tomato (Solanum lycopersicum), medicago (Medicago truncatula) and pea (Pisum sativum). PMID:25449728

Bar, Maya; Ori, Naomi

2015-02-01

344

Classification and quantification of leaf curvature  

PubMed Central

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

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

2010-01-01

345

Effect of Leaf Rolling on Gas Exchange and Leaf Temperature of Andropogon gerardii and Spartina pectinata  

Microsoft Academic Search

We examined the effect of leaf rolling on CO, and water vapor exchange of two C, prairie grasses with contrasting patterns of leaf rolling. Andropogon gerardii (big bluestem) is a drought-resistant species with predominantly hypostomatal leaves that fold (adaxial surface inward) in response to low leaf water potential, while leaves of Spartina pectinata (prairie cordgrass), a mesic species, are epistomatal

Scott A. Heckathorn; Evan H. DeLucia

1991-01-01

346

Modeling individual leaf area of ginger ( Zingiber officinale Roscoe) using leaf length and width  

Microsoft Academic Search

Leaf area estimation is an important biometrical observation one has to do for comparing plant growth in field and pot experiments. In this study, a leaf area estimation model was developed for ginger (Zingiber officinale Roscoe), using linear measurements of leaf length (L) and maximum width (W). Leaves from five ginger varieties (Varada, Rejatha, Mahima, Maran and Himachal) were used

K. Kandiannan; Utpala Parthasarathy; K. S. Krishnamurthy; C. K. Thankamani; V. Srinivasan

2009-01-01

347

Breath figures on leaf surfacesformation and effects of microscopic leaf wetness  

PubMed Central

Microscopic leaf wetness means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 ?m, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past. PMID:24167510

Burkhardt, Juergen; Hunsche, Mauricio

2013-01-01

348

Characterization of the spinach chloroplast genes for the S4 ribosomal protein, tRNA(Thr) (UGU) and tRNA (Ser) (GGA).  

PubMed

The map location and nucleotide sequence of the genes for the S4 ribosomal protein (rps4) and for tRNA(Thr) (UGU) (trnT) and tRNA(Ser) (GGA) (trnS) on spinach chloroplast DNA have been determined. rps4 lies approximately 5 kb 3' to atpBE in the large single copy region and is transcribed in the same direction as atpBE. It has a 178 bp leader sequence, a 603 bp coding region and 620 bp 3' tail. The sequence of the coding region is 83% homologous with that of maize rps4 (29) and the deduced amino acid sequences from the two species are 7% homologous. The spinach and Escherichia coli S4 proteins are only 36% homologous. As in the case of maize, trnT lies upstream from and on the same strand as rps4 whereas trnS lies downstream and on the opposite strand. Transcription of rps4 apparently proceeds past trnS. PMID:24302158

Tahar, S B; Bottomley, W; Whitfeld, P R

1986-01-01

349

Natural rpoS mutations contribute to population heterogeneity in Escherichia coli O157:H7 strains linked to the 2006 US spinach-associated outbreak.  

PubMed

We previously reported significantly different acid resistance between curli variants derived from the same Escherichia coli O157:H7 strain, although the curli fimbriae were not associated with this phenotypic divergence. Here we investigated the underlying molecular mechanism by examining the genes encoding the common transcriptional regulators of curli biogenesis and acid resistance. rpoS null mutations were detected in all curli-expressing variants of the 2006 spinach-associated outbreak strains, whereas a wild-type rpoS was present in all curli-deficient variants. Consequently curli-expressing variants were much more sensitive to various stress challenges than curli-deficient variants. This loss of general stress fitness appeared solely to be the result of rpoS mutation since the stress resistances could be restored in curli-expressing variants by a functional rpoS. Comparative transcriptomic analyses between the curli variants revealed a large number of differentially expressed genes, characterized by the enhanced expression of metabolic genes in curli-expressing variants, but a marked decrease in transcription of genes related to stress resistances. Unlike the curli-expressing variants of the 1993 US hamburger-associated outbreak strains (Applied Environmental Microbiology 78: 7706-7719), all curli-expressing variants of the 2006 spinach-associated outbreak strains carry a functional rcsB gene, suggesting an alternative mechanism governing intra-strain phenotypic divergence in E.coli O157:H7. PMID:25084652

Carter, Michelle Qiu; Louie, Jacqueline W; Huynh, Steven; Parker, Craig T

2014-12-01

350

Structural Basis of Efficient Electron Transport between Photosynthetic Membrane Proteins and Plastocyanin in Spinach Revealed Using Nuclear Magnetic Resonance[C][W][OA  

PubMed Central

In the photosynthetic light reactions of plants and cyanobacteria, plastocyanin (Pc) plays a crucial role as an electron carrier and shuttle protein between two membrane protein complexes: cytochrome b6f (cyt b6f) and photosystem I (PSI). The rapid turnover of Pc between cyt b6f and PSI enables the efficient use of light energy. In the Pc-cyt b6f and Pc-PSI electron transfer complexes, the electron transfer reactions are accomplished within <10?4 s. However, the mechanisms enabling the rapid association and dissociation of Pc are still unclear because of the lack of an appropriate method to study huge complexes with short lifetimes. Here, using the transferred cross-saturation method, we investigated the residues of spinach (Spinacia oleracea) Pc in close proximity to spinach PSI and cyt b6f, in both the thylakoid vesicleembedded and solubilized states. We demonstrated that the hydrophobic patch residues of Pc are in close proximity to PSI and cyt b6f, whereas the acidic patch residues of Pc do not form stable salt bridges with either PSI or cyt b6f, in the electron transfer complexes. The transient characteristics of the interactions on the acidic patch facilitate the rapid association and dissociation of Pc. PMID:23032988

Ueda, Takumi; Nomoto, Naoko; Koga, Masamichi; Ogasa, Hiroki; Ogawa, Yuuta; Matsumoto, Masahiko; Stampoulis, Pavlos; Sode, Koji; Terasawa, Hiroaki; Shimada, Ichio

2012-01-01

351

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

352

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton 28.471 Below Leaf Grade...

2014-01-01

353

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

354

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton 28.471 Below Leaf Grade...

2013-01-01

355

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS COTTON CLASSING, TESTING, AND STANDARDS Standards Below Leaf Grade Cotton 28.471 Below Leaf Grade...

2012-01-01

356

Photovoltaic Leaf Area Meter Development and Testing  

Microsoft Academic Search

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

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

2008-01-01

357

Lindstr om Quantifiers and Leaf Language Definability  

E-print Network

and examine analogies to the concept of leaf language definability. The quantifier structure in a secondLindstr? om Quantifiers and Leaf Language Definability Hans­J?org Burtschick Fachbereich Informatik­ order sentence defining a language and the quantifier structure in a first­order sentence characterizing

Vollmer, Heribert

358

Rhythmic Leaf Movements: Physiological and Molecular Aspects  

Microsoft Academic Search

Daily periodic plant leaf movements, known since antiquity, are dramatic manifestations of osmotic motors regulated by the endogenous biological clock and by light, perceived by phytochrome and, possibly, by phototropins. Both the reversible movements and their regulation usually occur in specialized motor leaf organs, pulvini. The movements result from opposing volume changes in two oppositely positioned parts of the pulvinus.

Nava Moran

359

Leaf Histology--Two Modern Methods.  

ERIC Educational Resources Information Center

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

Freeman, H. E.

1984-01-01

360

Very Sparse Leaf Languages Lance Fortnow  

E-print Network

-- the languages defined in terms of the pattern appearing at the leaf-level a polynomial-time nondeterministic and fully explored. Given a polynomial-time nondeterministic Turing machine M that accepts all inputs on all that NP-complete sets are not polynomial-time many-one reducible to such balanced leaf language unless

Fortnow, Lance

361

EFFECTS OF DEOXYNIVALENOL ON BARLEY LEAF PIGMENTATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

362

Genetics of leaf blight resistance in wheat  

Microsoft Academic Search

Studies on the genetics of leaf blight caused byAlternaria triticina using generation mean analysis revealed that additive components played a major role, but that dominance components also contributed significantly in controlling the variability for leaf blight resistance in wheat crosses. Furthermore, the additive x additive type of epistasis was predominant in the first three crosses, whereas in the fourth cross

B. Sinha; R. M. Singh; U. P. Singh

1991-01-01

363

Easy Leaf Area: Automated digital image analysis for rapid and accurate measurement of leaf area1  

PubMed Central

Premise of the study: Measurement of leaf areas from digital photographs has traditionally required significant user input unless backgrounds are carefully masked. Easy Leaf Area was developed to batch process hundreds of Arabidopsis rosette images in minutes, removing background artifacts and saving results to a spreadsheet-ready CSV file. Methods and Results: Easy Leaf Area uses the color ratios of each pixel to distinguish leaves and calibration areas from their background and compares leaf pixel counts to a red calibration area to eliminate the need for camera distance calculations or manual ruler scale measurement that other software methods typically require. Leaf areas estimated by this software from images taken with a camera phone were more accurate than ImageJ estimates from flatbed scanner images. Conclusions: Easy Leaf Area provides an easy-to-use method for rapid measurement of leaf area and nondestructive estimation of canopy area from digital images. PMID:25202639

Easlon, Hsien Ming; Bloom, Arnold J.

2014-01-01

364

SPS Over Expression in Cotton and Its Effect on Lint Yield and Fiber Quality  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous research indicated that cool night temperatures may cause lower cotton lint yields and immature fiber. Biochemical analyses of leaf (source) and fiber (sink) metabolism indicated that increasing sucrose phosphate synthase (SPS) activity might increase lint yields and improve fiber quality a...

365

Inferring climate from angiosperm leaf venation networks.  

PubMed

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

Blonder, Benjamin; Enquist, Brian J

2014-10-01

366

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

PubMed Central

1. ATP sulphurylases were partially purified (2040-fold) from leaf tissue of Astragalus bisulcatus, Astragalus racemosus (selenium-accumulator species) and Astragalus hamosus and Astragalus sinicus (non-accumulator species). Activity was measured by sulphate-dependent PPiATP exchange. The enzymes were separated from pyrophosphatase and adenosine triphosphatase activities. The properties of the Astragalus ATP sulphurylases were similar to the spinach enzyme. 2. The ATP sulphurylases from both selenium-accumulator and non-accumulator species catalysed selenate-dependent PPiATP exchange; selenate competed with sulphate. The ratio of V(selenate)/V(sulphate) and Km(selenate)/Km(sulphate) was approximately the same for the enzyme from each species. 3. Sulphate-dependent PPiATP exchange was inhibited by ADP, chlorate and nitrate. The kinetics of the inhibition for each enzyme were consistent with an ordered reaction mechanism, in which ATP is the first substrate to react with the enzyme and PPi is the first product released. 4. Synthesis of adenosine 5?-[35S]sulphatophosphate from [35S]sulphate was demonstrated by coupling the Astragalus ATP sulphurylases with Mg2+-dependent pyrophosphatase; the reaction was inhibited by selenate. An analogous reaction using [75Se]selenate as substrate could not be demonstrated. PMID:4377098

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

1974-01-01

367

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

PubMed

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

Shaw, W H; Anderson, J W

1974-04-01

368

Anaerobic Capacities of Leaf Litter  

PubMed Central

Leaf litter displayed a capacity to spontaneously form organic acids, alcohols, phenolic compounds, H(inf2), and CO(inf2) when incubated anaerobically at 20(deg)C either as buffered suspensions or in a moistened condition in microcosms. Acetate was the predominant organic product formed regardless of the degree of litter decomposition. Initial rates of acetate formation in litter suspensions and microcosms approximated 2.6 and 0.53 (mu)mol of acetate per g (dry weight) of litter per h, respectively. Supplemental H(inf2) was directed towards the apparent acetogenic synthesis of acetate. Acetoclastic methanogenesis was induced by partially decomposed litter after extended lag phases; freshly fallen litter did not display this capacity. PMID:16535448

Kusel, K.; Drake, H. L.

1996-01-01

369

A model for leaf initiation  

PubMed Central

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

Abraham-Shrauner, Barbara; Pickard, Barbara G

2011-01-01

370

Optimizing leaf widths for a multileaf collimator  

NASA Astrophysics Data System (ADS)

The multileaf collimator (MLC) is becoming a standard accessory of modern linac in shaping radiation fields. However, for a given target (projection), the radiation field shaped by an MLC has a stepwise boundary and is not identical to the desired field that exactly conforms to the target. That means there are always under-blocked and/or over-blocked areas. The total area of discrepancy depends on MLC leaf widths. The purpose of this study is to develop an optimization model for determining leaf widths so that the total area of discrepancy between MLC-shaped fields and the desired ones can be minimized. The optimization model regards leaf widths as variables, the total area of discrepancy between MLC-shaped fields and the desired fields as an objective function, and the total width of all leaves as a constraint. A problem described by the model is solved with the hybrid of a simulated annealing technique (ASA, Lester Ingber, 1993) and a gradient technique (DONLP2, P Spellucci, 2001). The performance of the optimization model was evaluated on 634 target fields continuously selected from the patient database of a treatment planning system. The lengths of these fields ranged from 3.9 to 38.7 cm and had an average of 15.3 cm. The total area of discrepancy was compared between an MLC with optimal leaf widths and a conventional MLC with the same number of leaf pairs. Optimal leaf widths were obtained for an MLC with total leaf pairs of 28, 40 and 60, respectively, which corresponded to three types of conventional MLCs. The optimal leaf width first decreases slightly and then nonlinearly increases with the distance away from the central line. Compared with the MLC with conventional leaf width arrangement, the MLCs with optimal leaf width arrangement reduced the total area of discrepancy by 11.1%, 28.6% and 25.0%, respectively. Optimizing leaf widths can either improve the conformity of MLC-shaped fields to the treatment targets when the number of leaf pairs does not change, or reduce the number of leaf pairs without sacrifice of field conformity.

Cui, Weijie; Dai, Jianrong

2009-05-01

371

Deciduous leaf drop reduces insect herbivory.  

PubMed

Deciduous leaf fall is thought to be an adaptation that allows plants living in seasonal environments to reduce water loss and damage during unfavorable periods while increasing photosynthetic rates during favorable periods. Observations of natural variation in leaf shedding suggest that deciduous leaf fall may also allow plants to reduce herbivory. I tested this hypothesis by experimentally manipulating leaf retention for Quercus lobata and observing natural rates of herbivory. Quercus lobata is primarily deciduous although individuals show considerable natural variation in leaf retention. Oak saplings with no leaves through winter experienced reduced attack by cynipid gall makers the following spring. This pattern was consistent with the positive correlation between natural leaf persistence and gall numbers. These cynipids do not overwinter on the leaves that trees retain through winter, although they appear to use persistent leaves as oviposition cues. If these results are general for woody plants in continental temperate habitats, they suggest that an important and unrecognized consequence of deciduous leaf shedding may be a reduction in herbivore damage, and that this effect should be included in models of deciduous and evergreen behavior. PMID:17375327

Karban, Richard

2007-08-01

372

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

PubMed Central

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

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

2011-01-01

373

Zesty Spinach Omelet Ingredients  

E-print Network

large eggs 2 tablespoons water Dash cumin Dash salt Dash pepper Non stick cooking spray 1/4 cup salsa to bowl. Repeat for other egg. Use a fork to beat eggs together. 4. Mix in water, cumin, salt and pepper

Liskiewicz, Maciej

374

Quick Spinach Lasagna Ingredients  

E-print Network

Nutrition Assistance Program ­ SNAP. The Supple- mental Nutrition Assistance Program (SNAP) provides nutrition assistance to people with low income. It can help you buy nutritious foods for a better diet by the Expanded Food Nutrition Education Program, USDA, NIFA. VCEP-5NP2013 #12;

Liskiewicz, Maciej

375

Lemon Spinach Ingredients  

E-print Network

. This material is partially funded by USDA's Supplemental Nutrition Assistance Program ­ SNAP. The Supple- mental Nutrition Assistance Program (SNAP) provides nutrition assistance to people with low income. It can help you. This material was partially funded by the Expanded Food Nutrition Education Program, USDA, NIFA. VCEP-5NP2013

Liskiewicz, Maciej

376

Evaluation of Methane from Sisal Leaf Residue and Palash Leaf Litter  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

377

Calibration of the Minolta SPAD502 leaf chlorophyll meter  

Microsoft Academic Search

Use of leaf meters to provide an instantaneous assessment of leaf chlorophyll has become common, but calibration of meter output into direct units of leaf chlorophyll concentration has been difficult and an understanding of the relationship between these two parameters has remained elusive. We examined the correlation of soybean (Glycine max) and maize (Zea mays L.) leaf chlorophyll concentration, as

John Markwell; John C. Osterman; Jennifer L. Mitchell

1995-01-01

378

Leaf litter ant diversity in Guyana JOHN S. LAPOLLA1,  

E-print Network

-1 Leaf litter ant diversity in Guyana JOHN S. LAPOLLA1, *, TED SUMAN1 , JEFFREY SOSA-CALVO1 Shield, Leaf litter ants Abstract. Leaf litter ants are an important group of organisms for informing conservation plan- ning. This study presents the beginning of a leaf litter ant dataset for Guyana. Following

Schultz, Ted

379

Breakthrough Technologies Leaf Extraction and Analysis Framework Graphical User  

E-print Network

: Segmenting and Analyzing the Structure of Leaf Veins and Areoles1[W][OA] Charles A. Price*, Olga Symonova improved empirical understanding of leaf network structure. LEAF GUI takes images of leaves where veins and cleaning steps, returns a suite of statistics and information on the structure of leaf venation networks

Weitz, Joshua S.

380

What Is a Leaf? An Online Tutorial and Tests  

ERIC Educational Resources Information Center

A leaf is a fundamental unit in botany and understanding what constitutes a leaf is fundamental to many plant science activities. My observations and subsequent testing indicated that many students could not confidently and consistently recognise a leaf from a leaflet, or recognise basic leaf arrangements and the various types of compound or

Burrows, Geoffrey

2008-01-01

381

Simulating Leaf Area of Corn Plants at Contrasting Water Status  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

382

Elevated CO and leaf shape: Are dandelions getting toothier?  

Microsoft Academic Search

Heteroblastic leaf development in Taraxacum officinale is compared between plants grown under ambient (350 ppm) vs. elevated (700 ppm) CO levels. Leaves of elevated CO plants exhibited more deeply incised leaf margins and relatively more slender leaf laminae than leaves of ambient CO plants. These differences were found to be significant in allometric analyses that controlled for differences in leaf

S. C. Thomas; F. A. Bazzaz

1996-01-01

383

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Smoking Leaf (H Group). 29.1163 Section...INSPECTION Standards Grades 29.1163 Smoking Leaf (H Group). This group...Tolerances H3FGood Quality Orange Smoking Leaf Mellow, open leaf...

2010-01-01

384

Changes in leaf mono- and sesquiterpene metabolism with nitrate availability and leaf age in Heterotheca subaxillaris  

Microsoft Academic Search

The concentration of leaf mono- and sesquiterpenes is greater in nitrate-limited than in nitrate-richHeterotheca subaxillaris plants and is highest in young leaves and declines with leaf age. To determine whether rates of volatile terpene synthesis and\\/or loss vary with nitrate availability and leaf age, incorporation of14C from photosynthetically fixed14CO2 and the subsequent loss of label was measured in plants grown

Charles A. Mihaliak; David E. Lincoln

1989-01-01

385

Short communication Leaf optical properties and photosynthetic leaf absorptances in several Australian seagrasses  

Microsoft Academic Search

Thisstudyinvestigated within-and among-species variability intheleafoptical properties ofeightlarge-bodiedseagrasses,Posidoniaaustralis, Posidonia sinuosa, Posidonia coriacea, Posidonia angustifolia, Amphibolis antarctica, Amphibolis griffithii, Zostera tasmanica, and Zostera capricorni and the small-bodied Halophila ovalis from the east and west coasts of Australia. Leaf spectral transmittance (TL(l)), reflectance (RL(l)), and non-photosynthetic absorptance (AL(NP)) were measured in order to calculate leaf spectral absorptance (AL(l)) and photosynthetic leaf absorptance (AL(PAR)).

Michael J. Durako

386

Photosynthesis and Respiration in Leaf Slices.  

ERIC Educational Resources Information Center

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

Brown, Simon

1998-01-01

387

Monitoring Air Quality with Leaf Yeasts.  

ERIC Educational Resources Information Center

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

Richardson, D. H. S.; And Others

1985-01-01

388

An Outdoor Lab Exercise Using Leaf Traps.  

ERIC Educational Resources Information Center

Presented is an activity which uses the annual process of abscission and leaf drop to illustrate all of the phases of the scientific method. Procedures, hypothesis formation, and typical results and conclusions are discussed. Alternative activities are suggested. (CW)

Bookman, Peter A.

1989-01-01

389

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2010 CFR

...conditioning are not regarded as manufacturing processes. Leaf tobacco does not include any manufactured or semimanufactured tobacco, stems which have been removed from leaves, cuttings, clippings, trimmings, shorts, or...

2010-01-01

390

7 CFR 29.3526 - Leaf scrap.  

Code of Federal Regulations, 2010 CFR

...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) 29.3526 Leaf scrap. A byproduct of...

2010-01-01

391

7 CFR 29.3526 - Leaf scrap.  

Code of Federal Regulations, 2011 CFR

...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Dark Air-Cured Tobacco (u.s. Types 35, 36, 37 and Foreign Type 95) 29.3526 Leaf scrap. A byproduct of...

2011-01-01

392

Understanding the cellular mechanism of recovery from freeze-thaw injury in spinach: possible role of aquaporins, heat shock proteins, dehydrin and antioxidant system.  

PubMed

Recovery from reversible freeze-thaw injury in plants is a critical component of ultimate frost survival. However, little is known about this aspect at the cellular level. To explore possible cellular mechanism(s) for post-thaw recovery (REC), we used Spinacia oleracea L. cv. Bloomsdale leaves to first determine the reversible freeze-thaw injury point. Freeze (-4.5C)-thaw-injured tissues (32% injury vs <3% in unfrozen control) fully recovered during post-thaw, as assessed by an ion leakage-based method. Our data indicate that photosystem II efficiency (Fv/Fm) was compromised in injured tissues but recovered during post-thaw. Similarly, the reactive oxygen species (O2 (-) and H2 O2 ) accumulated in injured tissues but dissipated during recovery, paralleled by the repression and restoration, respectively, of activities of antioxidant enzymes, superoxide dismutase (SOD) (EC. 1.14.1.1), and catalase (CAT) (EC.1.11.1.6) and ascorbate peroxidase (APX) (EC.1.11.1.11). Restoration of CAT and APX activities during recovery was slower than SOD, concomitant with a slower depletion of H2 O2 compared to O2 (-) . A hypothesis was also tested that the REC is accompanied by changes in the expression of water channels [aquaporines (AQPs)] likely needed for re-absorption of thawed extracellular water. Indeed, the expression of two spinach AQPs, SoPIP2;1 and So?TIP, was downregulated in injured tissues and restored during recovery. Additionally, a notion that molecular chaperones [heat shock protein of 70?kDa (HSP70s)] and putative membrane stabilizers [dehydrins (DHNs)] are recruited during recovery to restore cellular homeostasis was also tested. We noted that, after an initial repression in injured tissues, the expression of three HSP70s (cytosolic, endoplasmic reticulum and mitochondrial) and a spinach DHN (CAP85) was significantly restored during the REC. PMID:23981077

Chen, Keting; Arora, Rajeev

2014-03-01

393

Leaf Impressions: A Model for Carbonization  

NSDL National Science Digital Library

In this activity students make leaf impressions on paper to illustrate how carbonization works. They use the leaf press method to demonstrate staining as a model for carbonization, when living tissue leaves a carbon film in sediment and rock. The students will discover that many plant fossils are preserved through carbonization and that soft parts of animals including skin and fur have also been preserved as fossils through the process of carbonization.

Stephen Greb

394

Leaf dynamics and profitability in wild strawberries  

Microsoft Academic Search

Leaf dynamics and carbon gain were evaluated for two species of wild strawberry, Fragaria virginiana and F. vesca. Five populations on sites representing a gradient of successional regrowth near Ithaca, N.Y., U.S.A., were studied for two or three years each. A computer-based model of plant growth and CO2 exchange combined field studies of leaf biomass dynamics with previously-determined gas exchange

Thomas W. Jurik; Brian F. Chabot

1986-01-01

395

Summary Leaf structure has been shown to be an important determinant of leaf photosynthetic characteristics, yet the na-  

E-print Network

Summary Leaf structure has been shown to be an important determinant of leaf photosynthetic et al. 1997, 1999, Green 1998). However, the exact nature of this relationship between leaf structure and Hikosaka 1995, Reich et al. 1997). Recent studies indicate that the influence of leaf structure

Green, Scott

396

Genome Expression during Normal Leaf Development 1  

PubMed Central

Changes in genome expression during normal cellular and plastid development in the first leaf of young (7-day-old) wheat (Triticum aestivum var. Maris Dove) were investigated by examining homogeneous populations of leaf cells and plastids of several developmental ages present in the same leaf. The cells were characterized over a period immediately following the last cell division. All of the leaf cells had cytoplasmic contents and nuclei, and between 44% (young tissue) and 54% (older tissue) of the leaf cells were mesophyll cells. Chloroplast development was complete 36 hours after the chloroplasts had ceased dividing. Extremely large changes occurred in cellular constituents over a very short period of leaf development. Maximum rates of accumulation of ribulose bisphosphate carboxylase per mesophyll cell (80 picograms/hour), chlorophyll per mesophyll cell (9 picograms/hour), and 70S ribosomes per mesophyll cell (19 105/hour) were recorded. Total cellular DNA varied from 40 to 60 picograms/cell, reflecting the changes in nuclear and chloroplast DNA synthesis during different phases of cellular and chloroplast division. The period of maximum accumulation of protein, total RNA, and both 80S and 70S ribosomes occurred between 36 and 48 hours after the last cell division. Between 48 and 60 hours, 70S rRNA per cell and protein content per cell continued to increase as 80S rRNA per cell declined. Ribulose bisphosphate carboxylase per cell increased 20-fold between 15 and 60 hours. PMID:16662317

Dean, Caroline; Leech, Rachel M.

1982-01-01

397

Ginseng leaf-stem: bioactive constituents and pharmacological functions  

Microsoft Academic Search

Ginseng root is used more often than other parts such as leaf stem although extracts from ginseng leaf-stem also contain similar active ingredients with pharmacological functions. Ginseng's leaf-stems are more readily available at a lower cost than its root. This article reviews the pharmacological effects of ginseng leaf-stem on some diseases and adverse effects due to excessive consumption. Ginseng leaf-stem

Hongwei Wang; Dacheng Peng; Jingtian Xie

2009-01-01

398

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

PubMed

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

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

2002-09-01

399

Seasonal Changes in Leaf Area of Amazon Forests from Leaf Flushing and Abscission  

NASA Astrophysics Data System (ADS)

A large increase in near-infrared (NIR) reflectance of Amazon forests during the light-rich dry season and a corresponding decrease during the light-poor wet season has been observed in satellite measurements. This has been variously interpreted as seasonal changes in leaf area resulting from net leaf flushing in the dry season and net leaf abscission in the wet season, enhanced photosynthetic activity during the dry season from flushing new leaves and as change in leaf scattering and absorption properties between younger and older leaves covered with epiphylls. Reconciling these divergent views using theory and observations is the goal of this article. The observed changes in NIR reflectance of Amazon forests could be due to similar, but small, changes in NIR leaf albedo (reflectance plus transmittance) only, from exchanging older leaves with newer ones, with total leaf area unchanged. However, this argument ignores accumulating evidence from ground-based studies of higher leaf area in the dry season relative to the wet season, seasonal changes in litterfall and does not satisfactorily explain why NIR reflectance of these forests decreases in the wet season. A more convincing explanation for the observed increase in NIR reflectance during the dry season and decrease during the wet season is one that invokes changes in both leaf area and leaf optical properties. Such an argument is consistent with known phonological behavior of tropical forests, ground-based reports of seasonal changes in leaf area, litterfall, leaf optical properties and fluxes of evapotranspiration, and thus, reconciles the various seemingly divergent views.

Samanta, A.; Knyazikhin, Y.; Xu, L.; Dickinson, R.; Fu, R.; Costa, M. H.; Ganguly, S.; Saatchi, S. S.; Nemani, R. R.; Myneni, R.

2011-12-01

400

Seasonal changes in leaf area of Amazon forests from leaf flushing and abscission  

NASA Astrophysics Data System (ADS)

A large increase in near-infrared (NIR) reflectance of Amazon forests during the light-rich dry season and a corresponding decrease during the light-poor wet season has been observed in satellite measurements. This increase has been variously interpreted as seasonal change in leaf area resulting from net leaf flushing in the dry season or net leaf abscission in the wet season, enhanced photosynthetic activity during the dry season from flushing new leaves and as change in leaf scattering and absorption properties between younger and older leaves covered with epiphylls. Reconciling these divergent views using theory and observations is the goal of this article. The observed changes in NIR reflectance of Amazon forests could be due to similar, but small, changes in NIR leaf albedo (reflectance plus transmittance) resulting from the exchange of older leaves for newer ones, but with the total leaf area unchanged. However, this argument ignores accumulating evidence from ground-based reports of higher leaf area in the dry season than the wet season, seasonal changes in litterfall and does not satisfactorily explain why NIR reflectance of these forests decreases in the wet season. More plausibly, the increase in NIR reflectance during the dry season and the decrease during the wet season would result from changes in both leaf area and leaf optical properties. Such change would be consistent with known phenological behavior of tropical forests, ground-based reports of seasonal changes in leaf area, litterfall, leaf optical properties and fluxes of evapotranspiration, and thus, would reconcile the various seemingly divergent views.

Samanta, Arindam; Knyazikhin, Yuri; Xu, Liang; Dickinson, Robert E.; Fu, Rong; Costa, Marcos H.; Saatchi, Sassan S.; Nemani, Ramakrishna R.; Myneni, Ranga B.

2012-03-01

401

MULTI-LEAF TRACKING FROM FLUORESCENCE PLANT VIDEOS Xi Yin, Xiaoming Liu  

E-print Network

-level knowledge, it is imperative to track all leaves over time and accurately estimate the structure of each leaf-over-time labels for all leaves and their indi- vidual leaf structure such as the leaf tips. fluorescence video]. Leaf alignment estimates the leaf structure by aligning with a leaf template [4]. Leaf tracking tracks

402

Leaf miner-induced changes in leaf transmittance cause variations in insect respiration rates  

Microsoft Academic Search

Very little is known about alterations in microclimate when an herbivore feeds on host plant. Modifications of leaf transmittance properties induced by feeding activity of the leaf miner Phyllonorycter blancardella F. were measured using a spectrometer. Their effects on the herbivore's body temperature and respiration rate have been determined under controlled conditions and varying radiation level employing an infrared gas

Sylvain Pincebourde; Jrme Casas

2006-01-01

403

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

404

Leaf lifespan as a determinant of leaf structure and function among 23 amazonian tree species  

Microsoft Academic Search

The relationships between resource availability, plant succession, and species' life history traits are often considered key to understanding variation among species and communities. Leaf lifespan is one trait important in this regard. We observed that leaf lifespan varies 30-fold among 23 species from natural and disturbed communities within a 1-km radius in the northern Amazon basin, near San Carlos de

P. B. Reich; C. Uhl; M. B. Walters; D. S. Ellsworth

1991-01-01

405

Seasonal changes in leaf area of Amazon forests from leaf flushing and abscission  

E-print Network

Seasonal changes in leaf area of Amazon forests from leaf flushing and abscission Arindam Samanta,1 of Amazon forests during the light-rich dry season and a corresponding decrease during the light-poor wet season has been observed in satellite measurements. This increase has been variously interpreted

Goldberg, Bennett

406

Black leaf streak and viral leaf streak: New banana diseases in East Africa  

Microsoft Academic Search

Black leaf streak, caused by Mycosphaerella fijiensis a virulent pathogen of bananas and plantains, is recorded from Zanzibar. This is the first record of this important pathogen from East Africa. Viral leaf streak of bananas is also identified from Zanzibar. The presence of panama disease and high infestations of root nematode are also noted.

A. J. Dabek; J. M. Waller

1990-01-01

407

Specific leaf area and leaf dry matter content of plants growing in sand dunes  

Microsoft Academic Search

We investigated the variations in specific leaf area (SLA) and leaf dry matter content (LDMC) of 20 species (10 annuals and 10 perennials) that have different distributional patterns in the Kerqin Sandy Land in north- ern China. The main purpose of our study was to determine if SLA and\\/or LDMC could be used as indicators of plant resource-use strategy in

Yulin LI; Douglas A. JOHNSON; Yongzhong SU; Jianyuan CUI; Tonghui ZHANG

2005-01-01

408

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

PubMed

Leaf vein traits are implicated in the determination of gas exchange rates and plant performance. These traits are increasingly considered as causal factors affecting the 'leaf economic spectrum' (LES), which includes the light-saturated rate of photosynthesis, dark respiration, foliar nitrogen concentration, leaf dry mass per area (LMA) and leaf longevity. This article reviews the support for two contrasting hypotheses regarding a key vein trait, vein length per unit leaf area (VLA). Recently, Blonder et al. (2011, 2013) proposed that vein traits, including VLA, can be described as the 'origin' of the LES by structurally determining LMA and leaf thickness, and thereby vein traits would predict LES traits according to specific equations. Careful re-examination of leaf anatomy, published datasets, and a newly compiled global database for diverse species did not support the 'vein origin' hypothesis, and moreover showed that the apparent power of those equations to predict LES traits arose from circularity. This review provides a 'flux trait network' hypothesis for the effects of vein traits on the LES and on plant performance, based on a synthesis of the previous literature. According to this hypothesis, VLA, while virtually independent of LMA, strongly influences hydraulic conductance, and thus stomatal conductance and photosynthetic rate. We also review (i) the specific physiological roles of VLA; (ii) the role of leaf major veins in influencing LES traits; and (iii) the role of VLA in determining photosynthetic rate per leaf dry mass and plant relative growth rate. A clear understanding of leaf vein traits provides a new perspective on plant function independently of the LES and can enhance the ability to explain and predict whole plant performance under dynamic conditions, with applications towards breeding improved crop varieties. PMID:24123455

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

2013-10-01

409

Persimmon leaf flavonoid promotes brain ischemic tolerance  

PubMed Central

Persimmon leaf flavonoid has been shown to enhance brain ischemic tolerance in mice, but its mechanism of action remains unclear. The bilateral common carotid arteries were occluded using a micro clip to block blood flow for 10 minutes. After 10 minutes of ischemic preconditioning, 200, 100, and 50 mg/kg persimmon leaf flavonoid or 20 mg/kg ginaton was intragastrically administered per day for 5 days. At 1 hour after the final administration, ischemia/reperfusion models were estab-lished by blocking the middle cerebral artery for 2 hours. At 24 hours after model establishment, compared with cerebral ischemic rats without ischemic preconditioning or drug intervention, plasma endothelin, thrombomodulin and von Willebrand factor levels significantly decreased and intercel-lular adhesion molecule-1 expression markedly reduced in brain tissue from rats with ischemic pre-conditioning. Simultaneously, brain tissue injury reduced. Ischemic preconditioning combined with drug exposure noticeably improved the effects of the above-mentioned indices, and the effects of 200 mg/kg persimmon leaf flavonoid were similar to 20 mg/kg ginaton treatment. These results indicate that ischemic preconditioning produces tolerance to recurrent severe cerebral ischemia. However, persimmon leaf flavonoid can elevate ischemic tolerance by reducing inflammatory reactions and vascular endothelial injury. High-dose persimmon leaf flavonoid showed an identical effect to ginaton. PMID:25206573

Miao, Mingsan; Zhang, Xuexia; Bai, Ming; Wang, Linan

2013-01-01

410

An evaluation of direct and indirect mechanisms for the sink-regulation of photosynthesis in spinach: Changes in gas exchange, carbohydrates, metabolites, enzyme activities and steady-state transcript levels after cold-girdling source leaves  

Microsoft Academic Search

Mature source leaves of spinach (Spinacia oleracea L.) plants growing hydroponically in a 9 h light (350 mol photonsm-2 s-1)\\/15 h dark cycle at 20 C in a climate chamber were fitted with a cold girdle around the petiole, 2 h into the light period. Samples were taken 1, 3 and 7 h later, and at the end of

Anne Krapp; Mark Stitt

1995-01-01

411

Sucrose Accumulation in the Sugarcane Stem Is Regulated by the Difference between the Activities of Soluble Acid Invertase and Sucrose Phosphate Synthase.  

PubMed Central

To assess the relative importance of morphological and biochemical factors in the regulation of sucrose (Suc) accumulation in the sugarcane (Saccharum spp. hybrids) stem, we investigated morphological and biochemical correlates of Suc accumulation among parents and progeny of a family segregating for differences. In contrast to the parents, no relationship was observed between morphology and the level of Suc accumulation among the progeny. The level and timing of Suc accumulation in the whole stalk and within individual internodes was correlated with the down-regulation of soluble acid invertase (SAI) activity. High SAI activity prevented most, but not all, Suc accumulation. There was a critical threshold of SAI activity above which high concentrations of Suc did not accumulate. This low level of SAI activity was always exceeded in the internodes of the lower-Suc-storing genotypes. However, low activity of SAI was not sufficient by itself to account for the Suc accumulation in the higher-Suc-storing genotypes. Major differences in Suc accumulation among the population were attributed to the difference between activities of SAI and Suc phosphate synthase, provided SAI is below the critical threshold concentration. This result is not unexpected, since the pathway of Suc transport for storage involves Suc hydrolysis and resynthesis. PMID:12223829

Zhu, Y. J.; Komor, E.; Moore, P. H.

1997-01-01

412

Leaf and stem morphoanatomy of Petiveria alliacea.  

PubMed

Petiveria alliacea is a perennial herb native to the Amazonian region and used in traditional medicine for different purposes, such as diuretic, antispasmodic and anti-inflammatory. The morphoanatomical characterization of the leaf and stem was carried out, in order to contribute to the medicinal plant identification. The plant material was fixed, freehand sectioned and stained either with toluidine blue or astra blue and basic fuchsine. Microchemical tests were also applied. The leaf is simple, alternate and elliptic. The blade exhibits paracytic stomata on the abaxial side, non-glandular trichomes and dorsiventral mesophyll. The midrib is biconvex and the petiole is plain-convex, both traversed by collateral vascular bundles adjoined with sclerenchymatic caps. The stem, in incipient secondary growth, presents epidermis, angular collenchyma, starch sheath and collateral vascular organization. Several prisms of calcium oxalate are seen in the leaf and stem. PMID:16242265

Duarte, M R; Lopes, J F

2005-12-01

413

Pentacyclic triterpenoids from olive fruit and leaf.  

PubMed

This work establishes a new procedure for the extraction and analysis of pentacyclic triterpenes, with which fruits and leaves from three Spanish olive cultivars ("Picual", "Hojiblanca", and "Arbequina") has been studied. The leaf contains important amounts of oleanolic acid (3.0-3.5% DW), followed by significant concentrations of maslinic acid and minor levels of ursolic acid, erythrodiol, and uvaol. The abundance and profile of triterpenoids change during the leaf ontogeny. In the fruit, triterpenes are exclusively located in the epicarp at concentrations 30-fold lower than that in the leaf. Maslinic acid is the main triterpenoid, only accompanied of oleanolic acid. Along the ripening the levels of these triterpenes decreased. All the analyzed leaves and fruits come from the same agricultural estate, with identical climate and culturing conditions. For this reason, the found differences could majorly be attributable to the genetic factors of the olive cultivars. PMID:20712364

Guinda, Angeles; Rada, Mirela; Delgado, Teresa; Gutirrez-Adnez, Pilar; Castellano, Jos Mara

2010-09-01

414

Bacterial Leaf Scorch of Landscape Trees  

E-print Network

A newly described bacterium has been added to the host of factors that plague and weaken landscape trees. The bacterium Xylella fastidiosa, which clogs the waterconducting xylem cells, is associated with a leaf scorch of at least five tree species. Environmental factors such as drought, excessive salt, or root damage have long been known to cause leaf scorch. Not until 1978, however, were scientists able to culture X. fastidiosa and prove that this unique plant pathogen also causes leaf scorch. Although the effects of the pathogen on a wide range of plants were known for some years, the connection with landscape trees is recent. This bulletin describes the symptoms for five trees: elm, oak, sycamore, mulberry, and maple. Familiarity with the distinctive symptoms illustrated here should assist in accurately diagnosing this widespread tree disease.

National Park Service

415

Leaf-to-leaf distances and their moments in finite and infinite m-ary tree graphs  

E-print Network

We study the leaf-to-leaf distances on full and complete m-ary graphs using a recursive approach. In our formulation, leaves are ordered along a line. We find explicit analytical formulae for the sum of all paths for arbitrary leaf-to-leaf distance r as well as the average path lengths and the moments thereof. We show that the resulting explicit expressions can be recast in terms of Hurwitz-Lerch transcendants. Results for periodic trees are also given. For incomplete random binary trees, we provide first results by numerical techniques; we find a rapid drop of leaf-to-leaf distances for large r.

Andrew M. Goldsborough; S. Alex Rautu; Rudolf A. Rmer

2014-06-16

416

Leaf Stomata as Bioindicators of Environmental Change  

NSDL National Science Digital Library

Leaf stomatal densities can be determined by a simple laboratory technique and yet have wide application in understanding environmental change. Several researchers have evidence which indicates that stomatal densities change in response to changing atmospheric levels of carbon dioxide. Stomata may also vary in response to the amount of annual rainfall in different localities. Because this investigation involves climatic variations, it requires that many geographically dispersed sites collect and share data. In this experiment, leaves from two species of trees will be collected and the stomatal index on the upper and lower epidermis of each leaf will be determined.

Steve Case (University of Kansas REV)

1994-07-30

417

Phytochemical analysis of leaf callus of Bacopa  

E-print Network

a traditional medicinal plant in India, commonly known as brahmi. Used for different diseases such as- nervous disorder, respiratory problem, leprosy, splenomegaly, skin disease etc. In the present study, the ethanolic and aqueous extract of the leaf callus of Bacopa monnieri was investigated for its phytochemical analysis by modified Kirby-Bauer diffusion method.The finding of this study revealedthat the extract of the leaf callus of Bacopa monnieri revealed the presence of Tannins,flavonoids, glycosides, terpenoids, saponins, and steroids and absence of Anthroquione,Phenolic etc.

Sunil Kumar Singh

418

Preliminary Phytochemical Screening of Calotropis gigantea Leaf  

E-print Network

Abstract- Herbals plants are effective source of traditional and modern medicines, useful for primary health care. Plants are richest source of bioactive organic chemicals on earth. The active metabolites like Phytochemicals from the medicinal plants were under exploration for the development of novel and biodegradable effective drugs as an alternative to the ineffective contemporary medicine. Calotropis gigantea has great medicinal importance to treat fever, indigestion, cold, cough, cardio tonic, asthma, scabies etc. Phytochemical properties of leaf of Calotropis gigantea obtained from methanol and petroleum ether extracts were investigated.The results suggest that the Phytochemical properties of the leaf for using various ailments.

Suchita Singh; Sanchita Singh; R. M. Mishra; Mahesh Pal Shrivastava

419

Leaf phenomics: a systematic reverse genetic screen for Arabidopsis leaf mutants.  

PubMed

The study and eventual manipulation of leaf development in plants requires a thorough understanding of the genetic basis of leaf organogenesis. Forward genetic screens have identified hundreds of Arabidopsis mutants with altered leaf development, but the genome has not yet been saturated. To identify genes required for leaf development we are screening the Arabidopsis Salk Unimutant collection. We have identified 608 lines that exhibit a leaf phenotype with full penetrance and almost constant expressivity and 98 additional lines with segregating mutant phenotypes. To allow indexing and integration with other mutants, the mutant phenotypes were described using a custom leaf phenotype ontology. We found that the indexed mutation is present in the annotated locus for 78% of the 553 mutants genotyped, and that in half of these the annotated T-DNA is responsible for the phenotype. To quickly map non-annotated T-DNA insertions, we developed a reliable, cost-effective and easy method based on whole-genome sequencing. To enable comprehensive access to our data, we implemented a public web application named PhenoLeaf (http://genetics.umh.es/phenoleaf) that allows researchers to query the results of our screen, including text and visual phenotype information. We demonstrated how this new resource can facilitate gene function discovery by identifying and characterizing At1g77600, which we found to be required for proximal-distal cell cycle-driven leaf growth, and At3g62870, which encodes a ribosomal protein needed for cell proliferation and chloroplast function. This collection provides a valuable tool for the study of leaf development, characterization of biomass feedstocks and examination of other traits in this fundamental photosynthetic organ. PMID:24946828

Wilson-Snchez, David; Rubio-Daz, Silvia; Muoz-Viana, Rafael; Prez-Prez, Jos Manuel; Jover-Gil, Sara; Ponce, Mara Rosa; Micol, Jos Luis

2014-09-01

420

Is leaf dry matter content a better predictor of soil fertility than specific leaf area?  

PubMed Central

Background and Aims Specific leaf area (SLA), a key element of the worldwide leaf economics spectrum, is the preferred soft plant trait for assessing soil fertility. SLA is a function of leaf dry matter content (LDMC) and leaf thickness (LT). The first, LDMC, defines leaf construction costs and can be used instead of SLA. However, LT identifies shade at its lowest extreme and succulence at its highest, and is not related to soil fertility. Why then is SLA more frequently used as a predictor of soil fertility than LDMC? Methods SLA, LDMC and LT were measured and leaf density (LD) estimated for almost 2000 species, and the capacity of LD to predict LDMC was examined, as was the relative contribution of LDMC and LT to the expression of SLA. Subsequently, the relationships between SLA, LDMC and LT with respect to soil fertility and shade were described. Key Results Although LD is strongly related to LDMC, and LDMC and LT each contribute equally to the expression of SLA, the exact relationships differ between ecological groupings. LDMC predicts leaf nitrogen content and soil fertility but, because LT primarily varies with light intensity, SLA increases in response to both increased shade and increased fertility. Conclusions Gradients of soil fertility are frequently also gradients of biomass accumulation with reduced irradiance lower in the canopy. Therefore, SLA, which includes both fertility and shade components, may often discriminate better between communities or treatments than LDMC. However, LDMC should always be the preferred trait for assessing gradients of soil fertility uncoupled from shade. Nevertheless, because leaves multitask, individual leaf traits do not necessarily exhibit exact functional equivalence between species. In consequence, rather than using a single stand-alone predictor, multivariate analyses using several leaf traits is recommended. PMID:21948627

Hodgson, J. G.; Montserrat-Mart, G.; Charles, M.; Jones, G.; Wilson, P.; Shipley, B.; Sharafi, M.; Cerabolini, B. E. L.; Cornelissen, J. H. C.; Band, S. R.; Bogard, A.; Castro-Dez, P.; Guerrero-Campo, J.; Palmer, C.; Prez-Rontom, M. C.; Carter, G.; Hynd, A.; Romo-Dez, A.; de Torres Espuny, L.; Royo Pla, F.

2011-01-01

421

Molecular Models of Leaf Extracts  

NSDL National Science Digital Library

Our Featured Molecules this month come from the paper by Pelter et. al. on the analysis of leaf extracts by thin-layer chromatography (1). As the authors discuss, their experiment may be used in courses at various levels of the curriculum. The molecules discussed in the paper are also of wide interest both for their structural properties and their wide-ranging appearance in both natural and synthetic substances. Included in the molecule collection are all of the isomers for the molecules pictured in the text with the exception of menthyl acetate, for which only one structure is given (see below). All of these molecules have been optimized at the HF/631-G(d) level. The menthol family enantiomeric pairs of menthol, isomenthol, neomenthol and neoisomenthol provide a rich yet coherent group of molecules on which to base discussion of chirality, enantiomers and diastereomers. Treadwell and Black have described some of the differences in physical properties of four members of this family, and several other experiments using one or more menthols have been published in this Journal (2, 3). I have created a Web page in which the eight molecules are embedded in no particular order, and with no rational file names. This is being used in at least one of our organic sections to give students experience at identifying enantiomers, and diastereomers, and in applying R/S notation (4). As access to computational software becomes more common, and as efforts are being made to incorporate more relevant modeling experiments into all levels of the curriculum, the menthols again present some interesting possibilities. While students at the organic level know about enantiomers differing in their optical rotation, and about chiral molecules interacting with chiral and achiral environments, it is instructive for them to think of other ways in which enantiomers and diastereomers are the same or different. Three useful ways of checking to see whether two structures are truly enantiomers is to compute their total energies, vibrational spectra, and dipole moments. These calculations are available in most common computational packages. Figure 1 shows the results of energy calculations on optimized structures of the eight isomers. The enantiomeric pairs have, as expected, exactly the same total energy, while the various diastereomers differ in energy. The computation of the vibrational spectra is a very sensitive probe to determine whether two structures are optimized and enantiomeric or not. Structures that are almost enantiomeric, but not quite optimized, may exhibit similar energies, but the low frequency vibrations will be sensitive to any deviation from optimization. If two supposedly enantiomeric structures do not have the same computed vibrations, or if either shows a negative frequency, the structures need to be optimized more carefully. As with the vibrational frequencies, enantiomers should show identical dipole moments. Only one structure of the eight isomers in the menthyl acetate family is included in the collection, giving students the chance to build the other seven and verify their computed properties. Because of the central role that chirality plays in chemistry, and particularly in biochemistry, it seems appropriate to introduce some of these visualization and modeling exercises early in the curriculum, and in courses designed for students majoring in other areas. Students in various courses could pursue other aspects of these same molecules including odor and cooling properties, and green chemistry approaches to synthesizing menthols.

422

Large structures at high resolution: the 1.6 A crystal structure of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase complexed with 2-carboxyarabinitol bisphosphate.  

PubMed

Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) from spinach is a hexadecamer (L8S8, Mr = 550,000) consisting of eight large (L, 475 residues) and eight small subunits (S, 123 residues). High-resolution data collection on crystals with large unit cells is not a trivial task due to the effect of radiation damage and the large number of overlapping reflections when conventional data collection methods are used. In order to minimise these effects, data on rubisco were collected with a giant Weissenberg camera at long crystal to image-plate distances at the synchrotron of the Photon Factory, Japan. Relative to conventional data sets, this experimental arrangement allowed a 20 to 30-fold reduction of the X-ray dose/exposure time for data collection. This paper describes the refined 1.6 A crystal structure of activated rubisco complexed with a transition state analogue, 2-carboxyarabinitol-bisphosphate. The crystallographic asymmetric unit contains an L4S4 unit, representing half of the molecule. The structure presented here is currently the highest resolution structure for any protein of comparable size. Refinement of the model was carried out by restrained least squares techniques without non-crystallographic symmetry averaging. The results show that all L and S subunits have identical three-dimensional structures, and their arrangement within the hexadecamer has no intrinsic asymmetry. A detailed analysis of the high-resolution maps identified 30 differences in the sequence of the small subunit, indicating a larger than usual heterogeneity for this nuclear encoded protein in spinach. No such differences were found in the sequence of the chloroplast encoded large subunit. The transition state analogue is in the cis conformation at the active site suggesting a key role for the carbamate of Lys201 in catalysis. Analysis of the active site around the catalytically essential magnesium ion further indicates that residues in the second liganding sphere of the metal play a role in fine-tuning the acid-base character and the position of the residues directly liganded to the metal. PMID:8648644

Andersson, I

1996-05-31

423

DIGITAL IMAGE ANALYSIS OF ZOSTERA MARINA LEAF INJURY  

EPA Science Inventory

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

424

Microsoft PowerPoint - Leaf BRN09 POWERPOINT  

Cancer.gov

Oncology Recapitulates Oncology Recapitulates Phylogeny Phylogeny 2 2 nd nd Annual BRN Symposium Annual BRN Symposium March 17, 2009 March 17, 2009 Clifton Leaf Clifton Leaf Dinosaur cladogram The branching of amniotes Onward to mammals . . . And so

425

7 CFR 30.31 - Classification of leaf tobacco.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Classification of leaf tobacco. 30.31 Section 30.31 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2010-01-01

426

Distinguishing mangrove species with laboratory measurements of hyperspectral leaf reflectance  

E-print Network

Distinguishing mangrove species with laboratory measurements of hyperspectral leaf reflectance LE step in developing classification procedures for remotely acquired hyperspectral mapping of mangrove canopies, we conducted a laboratory study of mangrove leaf spectral reflectance at a study site

Wang, Le

427

7 CFR 51.1220 - Leaf or limb rub injury.  

Code of Federal Regulations, 2010 CFR

...VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION, CERTIFICATION, AND STANDARDS) United States Standards for Grades of Peaches Definitions 51.1220 Leaf or limb rub injury. Leaf or limb rub injury means that the scarring is not...

2010-01-01

428

Bioinformatic pipelines in Python with Leaf  

PubMed Central

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

2013-01-01

429

Toxicity evaluation of diazinon contaminated leaf litter  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

430

Yolk Pigments of the Mexican Leaf Frog  

Microsoft Academic Search

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

Guido V. Marinetti; Joseph T. Bagnara

1983-01-01

431

An Outbreak of Foxglove Leaf Poisoning  

Microsoft Academic Search

Comfrey (Symphytum officinale) leaves resemble those of foxglove (Digitalis purpurea) when the plant is not in bloom and, therefore, cardiac glycoside poisoning may occur when people confuse foxglove with comfrey. We report an outbreak of foxglove leaf poisoning following the use of alleged \\

Chun-Chi Lin; Chen-Chang Yang; Dong-Haur Phua; Jou-Fang Deng; Li-Hua Lu

2010-01-01

432

AN UPDATE ON XANTHOMONAS LEAF BLIGHT  

Technology Transfer Automated Retrieval System (TEKTRAN)

Xanthomonas leaf blight, caused by the bacterium Xanthomonas axonopodis pv. allii, is a common foliar disease of onion. Environmental, host, and cultural factors affect the severity of the disease, but reductions in yield of 20% or greater are common. This article presents a review of disease symp...

433

Leaf Stomata as Bioindicators: Stimulating Student Research  

ERIC Educational Resources Information Center

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

Case, Steven B.

2006-01-01

434

New leaf diseases of barley in Egypt.  

PubMed

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

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

1976-01-01

435

PHOTOSYNTHETIC ADAPTATION FROM THE LEAF TO LANDSCAPE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The foundation for understanding light processing by leaves is a detailed understanding of how the chloroplast operate within, and interact with, the environment of leaf. To convert the transient energy of light into stable chemical energy, the photo synthetic apparatus performs a series of energy t...

436

Mandatory Leaf Node Prediction in Hierarchical Multilabel Classification  

E-print Network

Mandatory Leaf Node Prediction in Hierarchical Multilabel Classification Wei Bi James T. Kwok Department of Computer Science and Engineering Hong Kong University of Science and Technology Clear Water Bay be required to always end at leaf nodes. This is called mandatory leaf node prediction (MLNP) and is par

Kwok, James Tin-Yau

437

7 CFR 29.3153 - Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

...percent injury tolerance. B3GF Good Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B4GF Fair Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B5GF Low Green-tan Leaf. Fleshy to medium...

2010-01-01

438

7 CFR 29.3153 - Leaf (B Group).  

Code of Federal Regulations, 2011 CFR

...percent injury tolerance. B3GF Good Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B4GF Fair Green-tan Leaf. Fleshy to medium body...percent injury tolerance. B5GF Low Green-tan Leaf. Fleshy to medium...

2011-01-01

439

Original article Nutrient release dynamics in decomposing leaf litter  

E-print Network

Original article Nutrient release dynamics in decomposing leaf litter in two Mediterranean 1997) Summary - The release and dynamics of macronutrients from decomposing leaf litter were determined were studied after leaf-litter exchanges between the French stand and a Spanish stand. Nylon litter

Paris-Sud XI, Université de

440

On the Relevance and Control of Leaf Angle  

Microsoft Academic Search

Plants can have constitutive leaf angles that are fixed and do not vary much among different growth environments. Several species, however, have the ability to actively adjust their leaf angles. Active leaf repositioning can be functional in avoiding detrimental environmental conditions, such as avoidance of heat stress and complete submergence, or can be, for example, utilized to maximize carbon gain

M. van Zanten; T. L. Pons; J. A. M. Janssen; L. A. C. J. Voesenek; A. J. M. Peeters

2010-01-01

441

Turbine rotor-stator leaf seal and related method  

DOEpatents

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

Herron, William Lee (Cincinnati, OH); Butkiewicz, Jeffrey John (Simpsonville, SC)

2003-01-01

442

Cenozoic paleotemperatures and leaf physiognomy A European perspective  

Microsoft Academic Search

For 21 European leaf-floras (with a focus on Central Europe), which span a stratigraphic range from the Late Eocene to the Pliocene, paleoclimate estimates have been calculated using five different quantitative techniques: (a) leaf margin analysis (LMA1), using a regression model based on data from East Asia, (b) the multivariate Climate Leaf Analysis Multivariate Programm (CLAMP) technique, based on data

Dieter Uhl; Stefan Klotz; Christopher Traiser; Christine Thiel; Torsten Utescher; Elizabeth Kowalski; David L. Dilcher

2007-01-01

443

Computer-aided plant species identification (CAPSI) based on leaf  

E-print Network

an easy and automatic method that can correctly discriminate and recognize leaf shapes of different the CSS method and applied it to leaf classification with self-intersection. Wang et al. (2002, 2003Computer-aided plant species identification (CAPSI) based on leaf shape matching technique Ji

Hefei Institute of Intelligent Machines

444

Red Leaf Resources and the Commercialization of Oil Shale  

E-print Network

Red Leaf Resources and the Commercialization of Oil Shale #12;About Red Leaf Resources 2006 Company commercial development field activities #12;Highlights Proven, Revolutionary Oil Shale Extraction Process Technology Significant Owned Oil Shale Resource #12;· The executive management team of Red Leaf Resources

Utah, University of

445

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

446

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

PubMed Central

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

2013-01-01

447

Seasonal variation in Daucus carota leaf-surface and leaf-tissue chemical profiles  

Microsoft Academic Search

The purpose of this work was to document seasonal changes in leaf-surface and whole-leaf chemistry of Daucus carota cohorts that differed in life-cycle phenology (winter annual, annual, or biennial), with particular focus on compounds that serve as contact oviposition stimulants for Papilio polyxenes, the black swallowtail butterfly. Cohorts of carrot plants exhibiting different life-cycle phenologies were established, and plants from

Janie S Brooks; Paul Feeny

2004-01-01

448

Fabrication of biomimetic superhydrophobic surfaces inspired by lotus leaf and silver ragwort leaf  

NASA Astrophysics Data System (ADS)

Inspired by the self-cleaning lotus leaf and silver ragwort leaf, here we demonstrate the fabrication of biomimetic superhydrophobic fibrous mats via electrospinning polystyrene (PS) solution in the presence of silica nanoparticles. The resultant electrospun fiber surfaces exhibited a fascinating structure with the combination of nano-protrusions and numerous grooves due to the rapid phase separation in electrospinning. The content of silica nanoparticles incorporated into the fibers proved to be the key factor affecting the fiber surface morphology and hydrophobicity. The PS fibrous mats containing 14.3 wt% silica nanoparticles showed a stable superhydrophobicity with a water contact angle as high as 157.2, exceeding that (147) of the silver ragwort leaf and approaching that (160) of the lotus leaf. The superhydrophobicity was explained by the hierarchical surfaces increasing the surface roughness which trapped more air under the water droplets that fell on the fibers.Inspired by the self-cleaning lotus leaf and silver ragwort leaf, here we demonstrate the fabrication of biomimetic superhydrophobic fibrous mats via electrospinning polystyrene (PS) solution in the presence of silica nanoparticles. The resultant electrospun fiber surfaces exhibited a fascinating structure with the combination of nano-protrusions and numerous grooves due to the rapid phase separation in electrospinning. The content of silica nanoparticles incorporated into the fibers proved to be the key factor affecting the fiber surface morphology and hydrophobicity. The PS fibrous mats containing 14.3 wt% silica nanoparticles showed a stable superhydrophobicity with a water contact angle as high as 157.2, exceeding that (147) of the silver ragwort leaf and approaching that (160) of the lotus leaf. The superhydrophobicity was explained by the hierarchical surfaces increasing the surface roughness which trapped more air under the water droplets that fell on the fibers. Electronic supplementary information (ESI) available: Preparation procedure and characterization of microfibrous polystyrene mats. See DOI: 10.1039/c0nr00812e

Lin, Jinyou; Cai, Yu; Wang, Xianfeng; Ding, Bin; Yu, Jianyong; Wang, Moran

2011-03-01

449

Disguising the Leaf Surface: The Use of Leaf Coatings for Plant Disease Control  

Microsoft Academic Search

The ability of fungal pathogens to develop resistance to fungicides and to overcome genetic resistance in their hosts, coupled\\u000a with growing public concern for the environment, means that there is an urgent need for novel methods of disease control.\\u000a The leaf surface provides the first barrier that fungi must overcome in order to gain access to the leaf, but it

Dale R. Walters

2006-01-01

450

The use of leaf disk inoculations in assessing resistance to coffee leaf rust (Hemileia vastatrix)  

Microsoft Academic Search

The suitability of inoculations of leaf disks of 1.8 cm diameter in determining resistance of coffee toHemileia vastatrix, the causal agent of coffee leaf rust, was studied. Results obtained by this method were similar to those obtained by greenhouse tests with respect to reaction types of coffee plants with complete and\\/or major gene resistance. The efficacy of the method in

A. B. Eskes

1982-01-01

451

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

PubMed

Plant materials derived from the Aloe plant are used as cosmetic ingredients, including Aloe Andongensis Extract, Aloe Andongensis Leaf Juice, Aloe Arborescens Leaf Extract, Aloe Arborescens Leaf Juice, Aloe Arborescens Leaf Protoplasts, Aloe Barbadensis Flower Extract, Aloe Barbadensis Leaf, Aloe Barbadensis Leaf Extract, Aloe Barbadensis Leaf Juice, Aloe Barbadensis Leaf Polysaccharides, Aloe Barbadensis Leaf Water, Aloe Ferox Leaf Extract, Aloe Ferox Leaf Juice, and Aloe Ferox Leaf Juice Extract. These ingredients function primarily as skin-conditioning agents and are included in cosmetics only at low concentrations. The Aloe leaf consists of the pericyclic cells, found just below the plant's skin, and the inner central area of the leaf, i.e., the gel, which is used for cosmetic products. The pericyclic cells produce a bitter, yellow latex containing a number of anthraquinones, phototoxic compounds that are also gastrointestinal irritants responsible for cathartic effects. The gel contains polysaccharides, which can be acetylated, partially acetylated, or not acetylated. An industry established limit for anthraquinones in aloe-derived material for nonmedicinal use is 50 ppm or lower. Aloe-derived ingredients are used in a wide variety of cosmetic product types at concentrations of raw material that are 0.1% or less, although can be as high as 20%. The concentration of Aloe in the raw material also may vary from 100% to a low of 0.0005%. Oral administration of various anthraquinone components results in a rise in their blood concentrations, wide systemic distribution, accumulation in the liver and kidneys, and excretion in urine and feces; polysaccharide components are distributed systemically and metabolized into smaller molecules. aloe-derived material has fungicidal, antimicrobial, and antiviral activities, and has been effective in wound healing and infection treatment in animals. Aloe barbadensis (also known as Aloe vera)-derived ingredients were not toxic in acute oral studies using mice and rats. In parenteral studies, the LD(50) using mice was > 200 mg/kg, rats was > 50 mg/kg, and using dogs was > 50 mg/kg. In intravenous studies the LD(50) using mice was > 80 mg/kg, rats was > 15 mg/kg, and dogs was > 10 mg/kg. The 14-day no observed effect level (NOEL) for the Aloe polysaccharide, acemannan, in the diet of Sprague-Dawley rats, was 50,000 ppm or 4.1 to 4.6 g/kg day(-1). In a 3-month study using mice, Aloe vera (extracted in ethanol) given orally in drinking water at 100 mg/kg produced reproductive toxicity, inflammation, and mortality above that seen in control animals. Aloe vera extracted in methanol and given to mice at 100 mg/kg in drinking water for 3 months caused significant sperm damage compared to controls. Aloe barbadensis extracted with water and given to pregnant Charles Foster albino rats on gestational days (GDs) 0 through 9 was an abortifacient and produced skeletal abnormalities. Both negative and positive results were found in bacterial and mammalian cell genotoxicity assays using Aloe barbadensis-derived material, Aloe Ferox-derived material, and various anthraquinones derived from Aloe. Aloin (an anthraquinone) did not produce tumors when included in the feed of mice for 20 weeks, nor did aloin increase the incidence of colorectal tumors induced with 1,2-dimethylhydrazine. Aloe-emodin (an anthraquinone) given to mice in which tumor cells had been injected inhibited growth of malignant tumors. Other animal data also suggest that components of Aloe inhibit tumor growth and improve survival. Various in vitro assays also demonstrated anticarcinogenic activity of aloe-emodin. Diarrhea was the only adverse effect of note with the use of Aloe-derived ingredients to treat asthma, ischemic heart disease, diabetes, ulcers, skin disease, and cancer. Case reports include acute eczema, contact urticaria, and dermatitis in individuals who applied Aloe-derived ingredients topically. The Cosmetic Ingredient Review Expert Panel concluded that anthraquinone levels in the several Aloe Barbaden

2007-01-01

452

Atmospheric application of trace amounts of nitric oxide enhances tolerance to salt stress and improves nutritional quality in spinach (Spinacia oleracea L.).  

PubMed

The increased salinity in greenhouses has become a problem of great concern. In this study, it was observed that the salt-induced oxidative damages (indicated by MDA, H2O2 and antioxidant enzymes, including POD, SOD and CAT) could be alleviated by application of NO gas. Consequently, although both photosynthesis and growth in plants were inhibited by NaCl stress, they were restored by NO gas application, and the fresh and dry biomasses of edible parts increased by 60% and 27% over NaCl stress treatment, respectively. Furthermore, gaseous NO application also significantly elevated the levels of several antioxidation-associated compounds such as proline, ascorbate, glutathione, total phenolics and flavonoids, as well as the total antioxidant capacity (indicated by DPPH scavenging activity) in NaCl-treated plants. Keeping in mind all of the above, we concluded that atmospheric application of trace amounts of nitric oxide gas could be an effective strategy for improving both biomass production and nutrition quality in spinach under salt stress. PMID:25466105

Du, Shao-Ting; Liu, Yue; Zhang, Peng; Liu, Hui-Jun; Zhang, Xue-Qing; Zhang, Ran-Ran

2015-04-15

453

Preconcentration and trace determination of cadmium in spinach and various water samples by temperature-controlled ionic liquid dispersive liquid phase microextraction.  

PubMed

A sensitive and selective method for the preconcentration and separation of sub g L-1 levels of cadmium ions in aqueous solutions with high salt contents is described. The developed method is based on temperature-controlled ionic liquid dispersive liquid phase microextraction of cadmium using the 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (ionic liquid (IL)) as an extractant followed by flame atomic absorption spectrometry determination. The extraction of cadmium ions from the aqueous solution into the fine droplets of IL was performed with dithizone as the chelating agent. Some predominant factors affecting the preconcentration of cadmium ions were evaluated and optimized. Under the optimum conditions, the calibration graph was linear over the concentration range from 0.6-20.0 g L-1 of cadmium and the limit of detection (LOD) was 0.2 g L-1. The enrichment factor was found to be 25. The developed method was successfully applied to the determination of cadmium in spinach and water samples. PMID:24664344

Rahnama, Reyhaneh; Mansoursamaei, Nazanin; Jamali, Mohammad Reza

2014-01-01

454

Multi-locus tree and species tree approaches toward resolving a complex clade of downy mildews (Straminipila, Oomycota), including pathogens of beet and spinach.  

PubMed

Accurate species determination of plant pathogens is a prerequisite for their control and quarantine, and further for assessing their potential threat to crops. The family Peronosporaceae (Straminipila; Oomycota) consists of obligate biotrophic pathogens that cause downy mildew disease on angiosperms, including a large number of cultivated plants. In the largest downy mildew genus Peronospora, a phylogenetically complex clade includes the economically important downy mildew pathogens of spinach and beet, as well as the type species of the genus Peronospora. To resolve this complex clade at the species level and to infer evolutionary relationships among them, we used multi-locus phylogenetic analysis and species tree estimation. Both approaches discriminated all nine currently accepted species and revealed four previously unrecognized lineages, which are specific to a host genus or species. This is in line with a narrow species concept, i.e. that a downy mildew species is associated with only a particular host plant genus or species. Instead of applying the dubious name Peronospora farinosa, which has been proposed for formal rejection, our results provide strong evidence that Peronospora schachtii is an independent species from lineages on Atriplex and apparently occurs exclusively on Beta vulgaris. The members of the clade investigated, the Peronospora rumicis clade, associate with three different host plant families, Amaranthaceae, Caryophyllaceae, and Polygonaceae, suggesting that they may have speciated following at least two recent inter-family host shifts, rather than contemporary cospeciation with the host plants. PMID:25772799

Choi, Young-Joon; Klosterman, Steven J; Kummer, Volker; Voglmayr, Hermann; Shin, Hyeon-Dong; Thines, Marco

2015-05-01

455

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

PubMed Central

In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This worldwide leaf economics spectrum consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes. PMID:25165520

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

2014-01-01

456

Tissue-level leaf toughness, but not lamina thickness, predicts sapling leaf lifespan and shade tolerance of  

E-print Network

, leaf toughness, ontogenetic shifts, sapling shade tolerance, structural equation modeling, tropical as their ontogenetic changes, for structure-level leaf toughness and regen- eration ecology of 19 tropical tree species additively to the structure-level toughness (leaf mass per area and work-to-shear). Species with dense

Kitajima, Kaoru

457

The effect of elevated CO2 on diel leaf growth cycle, leaf carbohydrate content and canopy growth  

E-print Network

The effect of elevated CO2 on diel leaf growth cycle, leaf carbohydrate content and canopy growth%) in the growing leaf in elevated CO2, suggesting diversion of glucose to starch or other carbohydrates, making of these trees to elevated CO2 is discussed. Keywords: biomass, Biosphere 2 Laboratory, carbohydrates, elevated

Barron-Gafford, Greg

458

Living With Limited Water, Part II: Dynamics of Leaf Rolling, Leaf Water Homeostasis and Water Economy by Hybrid Rice  

Microsoft Academic Search

Change in leaf form or shape has often been enumerated as a potential means of reducing transpiration by plants experiencing water deficit. Because leaf rolling is the first and foremost visible physiological response to water deficit in rice plant, its dynamic nature and impact on leaf water homeostasis and water conservation were studied in hybrid rice (Oryza sativa L.) in

S. Singh; T. N. Singh; J. S. Chauhan

2011-01-01

459

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

460

Use of NAP gene to manipulate leaf senescence in plants  

SciTech Connect

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

Gan, Susheng; Guo, Yongfeng

2013-04-16

461

Polarized and specular reflectance variation with leaf surface features  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

462

Variations in the polarized leaf reflectance of Sorghum bicolor  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

463

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

PubMed Central

Background Previous work has shown that leaf-cutting ants prefer to cut leaf material with relatively low fungal endophyte content. This preference suggests that fungal endophytes exact a cost on the ants or on the development of their colonies. We hypothesized that endophytes may play a role in their host plants defense against leaf-cutting ants. To measure the long-term cost to the ant colony of fungal endophytes in their forage material, we conducted a 20-week laboratory experiment to measure fungal garden development for colonies that foraged on leaves with low or high endophyte content. Results Colony mass and the fungal garden dry mass did not differ significantly between the low and high endophyte feeding treatments. There was, however, a marginally significant trend toward greater mass of fungal garden per ant worker in the low relative to the high endophyte treatment. This trend was driven by differences in the fungal garden mass per worker from the earliest samples, when leaf-cutting ants had been foraging on low or high endophyte leaf material for only 2 weeks. At two weeks of foraging, the mean fungal garden mass per worker was 77% greater for colonies foraging on leaves with low relative to high endophyte loads. Conclusions Our data suggest that the cost of endophyte presence in ant forage material may be greatest to fungal colony development in its earliest stages, when there are few workers available to forage and to clean leaf material. This coincides with a period of high mortality for incipient colonies in the field. We discuss how the endophyte-leaf-cutter ant interaction may parallel constitutive defenses in plants, whereby endophytes reduce the rate of colony development when its risk of mortality is greatest. PMID:23140096

2012-01-01

464

Leaf-wax n-alkanes record the plantwater environment at leaf flush  

PubMed Central

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

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

2013-01-01

465

Leaf area partitioning as an important factor in growth.  

PubMed

Despite continuing efforts to correlate unit area rates of photosynthesis of crop varieties with growth rates, there has been little or no success. It is reasonable to assume that partitioning of photosynthate into new leaf area is an important component of growth. Accordingly, an expression was developed to measure leaf area partitioning. Using growth analysis techniques, relative growth rates were compared to net assimilation rates, partitioning of daily weight gain into new leaf area, and partitioning of daily weight gain into new leaf weight of nine species grown in growth chambers under three temperature regimes. Day/night temperatures of 21/10, 32/21, and 38/27 C caused large differences in relative growth rates. Relative growth rates were closely correlated with leaf area partitioning in seven of the nine species, but were inversely correlated with leaf weight partitioning for six of the nine species. Relative growth rates were poorly correlated with net assimilation rates for five of the nine species. The product of net assimilation rate times leaf area partitioning is shown to be equal to the relative leaf area expansion rate.These results indicate that growth responses due to temperature shifts were more sensitive to changes in leaf area partitioning or relative leaf area expansion rates than to net assimilation rates. Because changes in leaf area partitioning or relative leaf area expansion rates can have an effect on relative growth rates that overshadow changes in net assimilation rates, and because net assimilation rates are largely a function of unit area rates of photosynthesis, the correlation of unit area rates of photosynthesis with growth should include consideration of leaf area partitioning or relative leaf area expansion rates. PMID:16659774

Potter, J R

1977-01-01

466

Carbohydrate Metabolism in Leaf Meristems of Tall Fescue 1  

PubMed Central

Our objective was to examine alterations in carbohydrate status of leaf meristems that are associated with nitrogen-induced changes in leaf elongation rates of tall fescue (Festuca arundinacea Schreb.). Dark respiration rates, concentrations of nonstructural carbohydrates, and soluble proteins were measured in leaf intercalary meristems and adjacent segments of elongating leaves. The two genotypes used differed by 43% in leaf elongation rate. Application of high nitrogen (336 kilograms per hectare) resulted in 140% higher leaf elongation rate when compared to plants receiving low nitrogen (22 kilograms per hectare). Leaf meristems of plants receiving high and low nitrogen had dark respiration rates of 5.4 and 2.9 microliters O2 consumed per milligram structural dry weight per hour, respectively. Concentrations of soluble proteins were lower while concentrations of fructan tended to be slightly higher in leaf meristems of low-nitrogen plants when compared to high-nitrogen plants. Concentrations of reducing sugars, nonreducing sugars, and takadiastase-soluble carbohydrate of leaf meristems were not affected by nitrogen treatment. Total nonstructural carbohydrates of leaf meristems averaged 44 and 39% of dry weight for low- and high-nitrogen plants, respectively. Within the leaf meristem, approximately 74 and 34% of the pool of total nonstructural carbohydrate could be consumed per day in high- and low-nitrogen plants, respectively, assuming no carbohydrate import to the meristem occurred. Plants were able to maintain high concentrations of nonstructural carbohydrates in leaf meristems despite a 3-fold range in leaf elongation rates, suggesting that carbohydrate synthesis and transport to leaf intercalary meristems may not limit leaf growth of these genotypes. PMID:16663466

Volenec, Jeffrey J.; Nelson, Curtis J.

1984-01-01

467

Transcriptional Analyses of Natural Leaf Senescence in Maize  

PubMed Central

Leaf senescence is an important biological process that contributes to grain yield in crops. To study the molecular mechanisms underlying natural leaf senescence, we harvested three different developmental ear leaves of maize, mature leaves (ML), early senescent leaves (ESL), and later senescent leaves (LSL), and analyzed transcriptional changes using RNA-sequencing. Three sets of data, ESL vs. ML, LSL vs. ML, and LSL vs. ESL, were compared, respectively. In total, 4,552 genes were identified as differentially expressed. Functional classification placed these genes into 18 categories including protein metabolism, transporters, and signal transduction. At the early stage of leaf senescence, genes involved in aromatic amino acids (AAAs) biosynthetic process and transport, cellular polysaccharide biosynthetic process, and the cell wall macromolecule catabolic process, were up-regulated. Whereas, genes involved in amino acid metabolism, transport, apoptosis, and response to stimulus were up-regulated at the late stage of leaf senescence. Further analyses reveals that the transport-related genes at the early stage of leaf senescence potentially take part in enzyme and amino acid transport and the genes upregulated at the late stage are involved in sugar transport, indicating nutrient recycling mainly takes place at the late stage of leaf senescence. Comparison between the data of natural leaf senescence in this study and previously reported data for Arabidopsis implies that the mechanisms of leaf senescence in maize are basically similar to those in Arabidopsis. A comparison of natural and induced leaf senescence in maize was performed. Athough many basic biological processes involved in senescence occur in both types of leaf senescence, 78.07% of differentially expressed genes in natural leaf senescence were not identifiable in induced leaf senescence, suggesting that differences in gene regulatory network may exist between these two leaf senescence programs. Thus, this study provides important information for understanding the mechanism of leaf senescence in maize. PMID:25532107

Zhang, Wei Yang; Xu, Yong Chao; Li, Wen Lan; Yang, Long; Yue, Xun; Zhang, Xian Sheng; Zhao, Xiang Yu

2014-01-01

468

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

469

The edge extraction of agricultural crop leaf  

NASA Astrophysics Data System (ADS)

In agricultural engineering, to ensure rational use of pesticide and improvement of crop production, computer image recognition technology is currently applied to help farmers to identify the degree of crop diseases. Considering the importance of feature extraction in this field, in this paper, we first present and discuss several widely used edge operator, including Sobel, Prewitt, Roberts, Canny and LoG. Furthermore, an experiment is conducted to compare performance and accuracy of five operators by applying them to a leaf image taken from agricultural crop for edge detection. The results of experiment show that, in practice, LoG edge operator is relatively a better choice and performs well for edge detection of agricultural crop leaf image.

Wang, Beilei; Cao, Ying; Xiao, Huiming; Jiang, Huiyan; Liu, Hongjuan

2009-07-01

470

BOREAS TE-5 Leaf Carbon Isotope Data  

NASA Technical Reports Server (NTRS)

The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. This documentation describes leaf carbon isotope data that were collected in 1993 and 1994 at the NSA and SSA OJP sites, the SSA OBS site, and the NSA UBS site. In addition, leaf carbon isotope data were collected in 1994 only at the NSA and SSA OA sites. These data was collected to provide seasonal integrated physiological information for 10 to 15 common species at these 6 BOREAS sites. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

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

2000-01-01

471

Preventing leaf identity theft with hormones.  

PubMed

Genetic analysis of plant development has begun to demonstrate the importance of hormone synthesis and transport in regulating morphogenesis. In the case of leaf development, for example, auxin pooling determines where a primordium will emerge and leads to the activation of transcription factors, which determine leaf identities by modulating abscisic acid (ABA) and gibberellic acid (GA) concentrations. Signal transduction studies suggest that negative regulation of transcription factors through protein turnover is commonly used as a mechanism of hormone action. Together, these findings suggest that auxin might degrade a repressor that allows the activation of genes that modulate ABA/GA ratios in emerging leaves. With our increased understanding of the molecular basis of hormone signaling, it is becoming possible to overlay important regulators onto signaling modules that determine morphological outputs. PMID:16054431

Lumba, Shelley; McCourt, Peter

2005-10-01

472

BOREAS TE-5 Leaf Gas Exchange Data  

NASA Technical Reports Server (NTRS)

The BOREAS TE-5 team collected measurements in the NSA and SSA on gas exchange, gas composition, and tree growth. The leaf photosynthetic gas exchange data were collected in the BOREAS NSA and the SSA from 06-Jun- 1994 to 13-Sep- 1994 using a LI-COR 6200 portable photosynthesis system. The data were collected to compare the photosynthetic capacity, stomata] conductance, and leaf intercellular CO, concentrations among the major tree species at the BOREAS sites. The data are average values from diurnal measurements on the upper canopy foliage (sun leaves). The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

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

2000-01-01

473

Cercospora Leaf Spot Disease of Sugar Beet  

Microsoft Academic Search

Cercospora leaf spot, incited by the fungus Cercospora beticola Sacc., is the most widespread and damaging sugar beet (Beta vulgaris L.) foliar disease. Under favorable for the disease agro-climatic conditions, insufficient control of epidemics leads to\\u000a significant sugar yield reduction and consequent heavy economic losses. Disease control strategies basically rely on a combination\\u000a of fungicide applications, growing resistant cultivars, and

George N. SkaracisOurania; Ourania I. Pavli; Enrico Biancardi

2010-01-01

474

Yolk pigments of the Mexican leaf frog.  

PubMed

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

Marinetti, G V; Bagnara, J T

1983-02-25

475

Identity of red currant spoon leaf virus  

Microsoft Academic Search

Summary Red currant spoon leaf virus, isolated from red currant in The Netherlands, is a strain of raspberry ringspot virus; it shares most of its antigenic groups with the type strain from Scottish raspberry but causes distinctive symptoms inPetunia hybrida. It differs from tomato ringspot virus, obtained byHildebrand (1942) from red currant in the United States.Klesser's (1951) red currant ringspot

B. D. Harrison

1961-01-01

476

Evolution of leaf warbler songs (Aves: Phylloscopidae)  

PubMed Central

Songs in passerine birds are important for territory defense and mating. Speciation rates in oscine passerines are so high, due to cultural evolution, that this bird lineage makes up half of the extant bird species. Leaf warblers are a speciose Old-World passerine family of limited morphological differentiation, so that songs are even more important for species delimitation. We took 16 sonographic traits from song recordings of 80 leaf warbler taxa and correlated them with 15 potentially explanatory variables, pairwise, and in linear models. Based on a well-resolved molecular phylogeny of the same taxa, all pairwise correlations were corrected for relatedness with phylogenetically independent contrasts and phylogenetic generalized linear models were used. We found a phylogenetic signal for most song traits, but a strong one only for the duration of the longest and of the shortest element, which are presumably inherited instead of learned. Body size of a leaf warbler species is a constraint on song frequencies independent of phylogeny. At least in this study, habitat density had only marginal impact on song features, which even disappeared through phylogenetic correction. Maybe most leaf warblers avoid the deterioration through sound propagation in dense vegetation by singing from exposed perches. Latitudinal (and longitudinal) extension of the breeding ranges was correlated with most song features, especially verse duration (longer polewards and westwards) and complexity (lower polewards). Climate niche or expansion history might explain these correlations. The number of different element types per verse decreases with elevation, possibly due to fewer resources and congeneric species at higher elevations. PMID:25691998

Tietze, Dieter Thomas; Martens, Jochen; Fischer, Balduin S; Sun, Yue-Hua; Klussmann-Kolb, Annette; Pckert, Martin

2015-01-01

477

Vertical leaf pressure filter LVAzh 225  

SciTech Connect

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

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

1984-01-01

478

Evolution of leaf warbler songs (Aves: Phylloscopidae).  

PubMed

Songs in passerine birds are important for territory defense and mating. Speciation rates in oscine passerines are so high, due to cultural evolution, that this bird lineage makes up half of the extant bird species. Leaf warblers are a speciose Old-World passerine family of limited morphological differentiation, so that songs are even more important for species delimitation. We took 16 sonographic traits from song recordings of 80 leaf warbler taxa and correlated them with 15 potentially explanatory variables, pairwise, and in linear models. Based on a well-resolved molecular phylogeny of the same taxa, all pairwise correlations were corrected for relatedness with phylogenetically independent contrasts and phylogenetic generalized linear models were used. We found a phylogenetic signal for most song traits, but a strong one only for the duration of the longest and of the shortest element, which are presumably inherited instead of learned. Body size of a leaf warbler species is a constraint on song frequencies independent of phylogeny. At least in this study, habitat density had only marginal impact on song features, which even disappeared through phylogenetic correction. Maybe most leaf warblers avoid the deterioration throug