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1

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

2

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

3

Sucrose Phosphate Synthase and Sucrose Accumulation at Low Temperature 1  

PubMed Central

The influence of growth temperature on the free sugar and sucrose phosphate synthase content and activity of spinach (Spinacia oleracea) leaf tissue was studied. When plants were grown at 25°C for 3 weeks and then transferred to a constant 5°C, sucrose, glucose, and fructose accumulated to high levels during a 14-d period. Predawn sugar levels increased from 14- to 20-fold over the levels present at the outset of the low-temperature treatment. Sucrose was the most abundant free sugar before, during, and after exposure to 5°C. Leaf sucrose phosphate synthase activity was significantly increased by the low-temperature treatment, whereas sucrose synthase and invertases were not. Synthesis of the sucrose phosphate synthase subunit was increased during and after low-temperature exposure and paralleled an increase in the steady-state level of the subunit. The increases in sucrose and its primary biosynthetic enzyme, sucrose phosphate synthase, are discussed in relation to adjustment of metabolism to low nonfreezing temperature and freezing stress tolerance. Images Figure 1 Figure 2 Figure 3 PMID:16652990

Guy, Charles L.; Huber, Joan L. A.; Huber, Steven C.

1992-01-01

4

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

5

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 ?3.8°C. In contrast, citrus leaves cold acclimated at a constant 10°C in growth chambers were freezing tolerant to about ?6°C. 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 10°C in a controlled environment. Spinach leaves cold acclimated at 5°C 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 ?1°C) 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

6

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

PubMed

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

Kuti, Joseph O; Konuru, Hima B

2004-01-14

7

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...

8

Sucrose metabolism: Anabaena sucrose-phosphate synthase and sucrose-phosphate phosphatase define minimal functional domains shuffled during evolution.  

PubMed

Based on the functional characterization of sucrose biosynthesis related protiens[SBP: sucrose-phosphate synthase (SPS), sucrose-phosphate phosphatase (SPP), and sucrose synthase (SuS)] in Anabaena sp. PCC7120 and sequence analysis, we have shown that SBP are restricted to cyanobacterium species and plants, and that they are multidomain proteins with modular architecture. Anabaena SPS, a minimal catalytic SPS unit, defines a glucosyltransferase domain present in all SPSs and SuSs. Similarly, Anabaena SPP defines a phosphohydrolase domain characteristic of all SPPs and some SPSs. Phylogenetic analysis points towards the evolution of modern cyanobacterial and plant SBP from a bidomainal common ancestral SPS-like gene. PMID:12062401

Cumino, Andrea; Curatti, Leonardo; Giarrocco, Laura; Salerno, Graciela L

2002-04-24

9

Sucrose-phosphate synthase activity and yield analysis of tomato plants transformed with maize sucrose-phosphate synthase  

Microsoft Academic Search

.   Sucrose synthesis is a major element of the interactions between photosynthesis and plant growth and development. Tomato (Lycopersicon esculentum Mill. cv. UC82B) plants transformed with maize sucrose-phosphate synthase (SPS; EC 2.3.1.14) expressed from either a ribulose-1,5-bisphosphate\\u000a carboxylase-oxygenase (Rubisco) small subunit promoter (SSU) or the cauliflower mosaic virus 35S promoter (35S) were used\\u000a to study effects of increased sucrose synthesis

Marianne M. Laporte; Julie A. Galagan; Joseph A. Shapiro; Michael R. Boersig; Christine K. Shewmaker; Thomas D. Sharkey

1997-01-01

10

Spinach protein factor and chlorophyllase  

Microsoft Academic Search

1.Spinach leaves contain a “Spinach Protein Factor” (SPF) which increases light sensitivity of colloidal chlorophylls in aqueous solution (Terpstra, 1967). SPF activity, measured in different fractions of spinach-leaf acetone-powder extracts obtained by gel filtration on DEAE- and CM-Sephadex, runs parallel with chlorophyllase activity. The same positive correlation is generally observed in aqueous extracts of certain small particles isolated from spinach-leaf

Willemke Terpstra; A. C. M. Weijman

1972-01-01

11

ADP/ATP Translocator from Pea Root Plastids (Comparison with Translocators from Spinach Chloroplasts and Pea Leaf Mitochondria).  

PubMed

The kinetic properties of the adenosine 5[prime]-diphosphate/adenosine 5[prime]-triphosphate (ADP/ATP) translocator from pea (Pisum sativum L.) root plastids were determined by silicone oil filtering centrifugation and compared with those of spinach (Spinacia oleracea L.) chloroplasts and pea leaf mitochondria. In addition, the ADP/ATP transporting activities from the above organelles were reconstituted into liposomes. The Km(ATP) value of the pea root ADP/ATP translocator was 10 [mu]M and that for ADP was 46 [mu]M. Corresponding values of the spinach ADP/ATP translocator were 25 [mu]M and 28 [mu]M, respectively. Comparable results were obtained for the reconstituted ATP transport activities. The transport was highly specific for ATP and ADP. Adenosine 5[prime]-monophosphate (AMP) caused only a slight inhibition and phosphoenolpyruvate and inorganic pyrophosphate caused no inhibition of ATP uptake. With pea root plastids and spinach chloroplasts, Km values >1 mM were obtained for ADP-glucose. Since the concentrations of ATP and ADP-glucose in the cytosolic compartment of spinach leaves have been determined as 2.5 and 0.6 mM, respectively, a transport of ADP-glucose by the ADP/ATP translocator does not appear to have any physiological significance in vivo. Although both the plastidial and the mitochondrial ADP/ATP translocators were inhibited to some extent by carboxyatractyloside, no immunological cross-reactivity was detected between the plastidial and the mitochondrial proteins. It seems probable that these proteins derive from different ancestors. PMID:12231920

Schunemann, D.; Borchert, S.; Flugge, U. I.; Heldt, H. W.

1993-09-01

12

Differential effects of severe water stress on linear and cyclic electron fluxes through Photosystem I in spinach leaf discs in CO 2 -enriched air  

Microsoft Academic Search

Linear and cyclic electron fluxes through Photosystem I in 1% CO2 were quantified in spinach leaf tissue under severe water stress. Using actinic light with a peak at 697 nm for preferential\\u000a light absorption by Photosystem I while also stimulating Photosystem II to improve redox poising, the cyclic electron flux\\u000a after 60 s of illumination was a substantial proportion (33–44%) of the

Husen Jia; Riichi Oguchi; Alexander B. Hope; James Barber; Wah Soon Chow

2008-01-01

13

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

PubMed

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

Niemira, Brendan A; Cooke, Peter H

2010-06-01

14

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

PubMed

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

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

2013-07-24

15

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

Microsoft Academic Search

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

Teck Khiang Chua; Janusz M. Bujnicki; T.-C. Tan; F. Huynh; B. K. Patel; J. Sivaraman; Y. Ogimoto; K. Miyano; H. Sawa

2008-01-01

16

Spinach protein factor and chlorophyllase.  

PubMed

1. Spinach leaves contain a "Spinach Protein Factor" (SPF) which increases light sensitivity of colloidal chlorophylls in aqueous solution (Terpstra, 1967). SPF activity, measured in different fractions of spinach-leaf acetone-powder extracts obtained by gel filtration on DEAE- and CM-Sephadex, runs parallel with chlorophyllase activity. The same positive correlation is generally observed in aqueous extracts of certain small particles isolated from spinach-leaf homogenates. It is suggested that SPF is a chlorophyllase. 2. Another, less active chlorophyllase was found in endive leaves. Evidence is presented that this chlorophyllase competes with the more active SPF chlorophyllase for available (bacterio)chlorophyll. The less active chlorophyllase is also present, in varying amounts, in spinach leaves. 3. SPF activity and chlorophyllase activity are influenced by phosphate in different concentrations in a similar way. 4. Both the SPF chlorophyllase and the less active chlorophyllase accelerate the conversion of colloidal bacteriochlorophyll from a form with red absorption bands at about 845 and 790 nm into a form with a main red band at about 775 nm; besides, the chlorophyllases cause the 775 nm band to be shifted to shorter wavelength (770-766 nm). The conversion by the less active chlorophyllase is inhibited by Ca(2+) (0.01 M). Light sensitivity of the 770-766-nm bacteriochlorophyll form is enhanced by the SPF chlorophyllase, but not by the less active chlorophyllase. PMID:24473911

Terpstra, W; Weijman, A C

1972-12-01

17

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

PubMed

Slightly acidic electrolyzed water (SAEW) is well known as a good sanitizer against foodborne pathogens on fresh vegetables. However, microbial reductions from SAEW treatment are not enough to ensure produce safety. Therefore, it is necessary to improve its antimicrobial efficiency by combining it with other appropriate approaches. This study examined the microbicidal activity of SAEW (pH 5.2-5.5, oxidation reduction potential 500-600 mV, available chlorine concentration 21-22 mg/l) on Chinese cabbage, lettuce, sesame leaf and spinach, four common fresh vegetables in Korea under same laboratory conditions. Subsequently, effects of ultrasonication and water wash to enhance the sanitizing efficacy of SAEW were studied, separately. Finally, an optimized simple and easy approach consisting of simultaneous SAEW treatment with ultrasonication (3 min) followed by water wash (150 rpm, 1 min) was developed (SAEW + US-WW). This newly developed hurdle treatment significantly enhanced the microbial reductions compared to SAEW treatment alone, SAEW treatment with ultrasonication (SAEW + US) and SAEW treatment followed by water wash (SAEW-WW) at room temperature (23 ± 2 °C). Microbial reductions of yeasts and molds, total bacteria count and inoculated Escherichia coli O157:H7 and Listeria monocytogenes were in the range of 1.76-2.8 log cfu/g on different samples using the new hurdle approach. PMID:23764218

Forghani, Fereidoun; Oh, Deog-Hwan

2013-10-01

18

Lemon Spinach Ingredients  

E-print Network

& SU, VSU, and the U.S.D.A. cooperating. Edwin J. Jones, Director, Virginia Cooperative ExtensionLemon Spinach Ingredients: 1 pound spinach, fresh 1/4 teaspoon black pepper 1 tablespoon lemon juice Directions 1. Wash the spinach. Trim off the stems. 2. Put the spinach, black pepper, and lemon

Liskiewicz, Maciej

19

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

20

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

Microsoft Academic Search

To understand the effect of water stress on the remobilization of prestored carbon reserves, the changes in the activities of starch hydrolytic enzymes and sucrose-phosphate synthase (SPS) in the stems of rice (Oryza sativa L.) during grain filling were investigated. Two rice cultivars, showing high lodging-resistance and slow remobilization, were grown in the field and subjected to well-watered (WW, ysoil

Jianchang Yang; Jianhua Zhang; Zhiqing Wang; Qingsen Zhu

2001-01-01

21

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

22

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

Microsoft Academic Search

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

Siegfried Hauch; Elisabeth Magel

1998-01-01

23

Quick Spinach Lasagna Ingredients  

E-print Network

Quick Spinach Lasagna Ingredients: 8 ounces whole wheat noodles 1/2 pound ground turkey 1 onion 15 of the onion, and peel off the brown layers. Cut onion in half and place flat side down. Slice into thin strips, keeping onion together. Turn and slice again to dice. 4. Once fat is drained from skillet, add onions

Liskiewicz, Maciej

24

Validation of a rice specific gene, sucrose phosphate synthase, used as the endogenous reference gene for qualitative and real-time quantitative PCR detection of transgenes.  

PubMed

With the development of transgenic crops, many countries have issued regulations to label the genetically modified organisms (GMOs) and their derived products. Polymerase Chain Reaction (PCR) methods are thought to be reliable and useful techniques for qualitative and quantitative detection of GMOs. These methods generally need to amplify the transgene and compare the amplified result with that of the corresponding reference gene to obtain reliable results. In this article, we reported the development of specific primers and probe for the rice (Oryza sativa) sucrose phosphate synthase (SPS) gene and PCR cycling conditions suitable for the use of this sequence as an endogenous reference gene in both qualitative and quantitative PCR assays. Both methods were assayed with 13 different rice varieties, and identical amplification products were obtained with all of them. No amplification products were observed when DNA samples from other species, such as wheat, maize, barley, tobacco, soybean, rapeseed, tomato, sunflower, carrot, pepper, eggplant, lupine, mung bean, plum, and Arabidopsis thaliana, were used as templates, which demonstrated that this system was specific for rice. In addition, the results of the Southern blot analysis confirmed that the SPS gene was a single copy in the tested rice varieties. In qualitative and quantitative PCR analyses, the detection sensitivities were 0.05 and 0.005 ng of rice genomic DNA, respectively. To test the practical use of this SPS gene as an endogenous reference gene, we have also quantified the beta-glucuronidase (GUS) gene in transgenic rice using this reference gene. These results indicated that the SPS gene was species specific, had one copy number, and had a low heterogeneity among the tested cultivars. Therefore, this gene could be used as an endogenous reference gene of rice and the optimized PCR systems could be used for practical qualitative and quantitative detection of transgenic rice. PMID:15161200

Ding, Jiayu; Jia, Junwei; Yang, Litao; Wen, Haibo; Zhang, Chengmei; Liu, Wenxuan; Zhang, Dabing

2004-06-01

25

Photoreduction of Sulfur Dioxide by Spinach Leaves and Isolated Spinach Chloroplasts  

PubMed Central

Labeled sulfur dioxide was found to be extensively absorbed by spinach (Spinacea oleracea L.) leaves. Labeled sulfides detected in leaf blades following fumigations with sulfur dioxide in light indicated that photoreduction of sulfur dioxide had occurred. Measurable proportions of this labeled sulfur was localized within the chloroplast fraction. Suspensions of isolated chloroplasts supplied with labeled sulfur dioxide contained labeled sulfides following a 30-minute illumination period in water-cooled reaction vessels. With reference to recent studies of the chloroplast sulfur reduction pathway, probable points of entry for sulfur dioxide and the subsequent release of hydrogen sulfide are discussed. PMID:16659572

Silvius, John E.; Baer, Charles H.; Dodrill, Sherman; Patrick, Homer

1976-01-01

26

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...

27

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

PubMed

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

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

2002-12-01

28

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

29

Zinc Deficiency, Carbonic Anhydrase, and Photosynthesis in Leaves of Spinach  

PubMed Central

A shortage in the zinc supply to spinach (Spinacia oleracea L.) drastically reduced carbonic anhydrase levels with little effect on net CO2 uptake per unit leaf area, except with the most severe zinc stresses. Under these conditions, carbonic anhydrase was below 10% and photosynthesis 60 to 70% of the control levels. When photosynthesis was measured at a range of CO2 supply levels, zinc-deficient leaves were less efficient at 300 to 350 microliters per liter CO2 and above, but the same as controls at lower CO2 levels. This suggests that carbonic anhydrase does not affect the diffusion of CO2, and that the effect of zinc deficiency was on the photosynthetic process itself. Our evidence does not support the hypothesis that carbonic anhydrase has some role in facilitating the supply of CO2 to the sites of carboxylation within the chloroplast. PMID:16658536

Randall, P. J.; Bouma, D.

1973-01-01

30

Spinach Thylakoid Polyphenol Oxidase 1  

PubMed Central

Polyphenol oxidase activity (E.C. 1.14.18.1) has been found in two enzyme species isolated from thylakoid membranes of spinach chloroplasts. The proteins were released from the membrane by sonication and purified >900-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzymes appear to be the tetramer and monomer of a subunit with a molecular weight of 42,500 as determined by lithium dodecyl sulfate gel electrophoresis. The higher molecular weight enzyme is the predominant form in freshly isolated preparations but on aging or further purification, the amount of lower molecular weight enzyme increases at the expense of the higher. Sonication releases polyphenol oxidase from the membrane largely in the latent state. C18 fatty acids, especially linolenic acid, are potent activators of the enzymic activity. In the absence of added fatty acids, the isolated enzyme spontaneously, but slowly, activates with time. Purified polyphenol oxidase utilizes o-diphenols as substrates and shows no detectable levels of monophenol or p-diphenol oxidase activities. The Km values for 3,4-dihydroxyphenylalanine and O2 are 6.5 and 0.065 millimolar, respectively. Suitable substrates include chlorogenic acid, catechol, caffeic acid, pyrogallol, and dopamine; however, the enzyme is substrate-inhibited by the last four at concentrations near their Km A large seasonal variation in polyphenol oxidase activity may result from a decrease in enzyme content rather than inhibition of the enzyme present. Images PMID:16661805

Golbeck, John H.; Cammarata, Kirk V.

1981-01-01

31

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

PubMed Central

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

Garcia, Raymond E.; Mudd, J. Brian

1978-01-01

32

Protoplast Volume:Water Potential Relationship and Bound Water Fraction in Spinach Leaves 1  

PubMed Central

Methods used to estimate the (nonosmotic) bound water fraction (BWF) (i.e. apoplast water) of spinach (Spinacia oleracea L.) leaves were evaluated. Studies using three different methods of pressure/volume (P/V) curve construction all resulted in a similar calculation of BWF; approximately 40%. The theoretically derived BWF, and the water potential (?w)/relative water content relationship established from P/V curves were used to establish the relationship between protoplast (i.e. symplast) volume and ?w. Another method of establishing the protoplast volume/?w relationship in spinach leaves was compared with the results from P/V curve experiments. This second technique involved the vacuum infiltration of solutions at a range of osmotic potentials into discs cut from spinach leaves. These solutions contained radioactively labeled H2O and sorbitol. This dual label infiltration technique allowed for simultaneous measurement of the total and apoplast volumes in leaf tissue; the difference yielded the protoplast volume. The dual label infiltration experiments and the P/V curve constructions both showed that below ?1 megapascals, protoplast volume decreases sharply with decreasing water potential; with 50% reduction in protoplast volume occurring at ?1.8 megapascals leaf water potential. PMID:16666983

Santakumari, Mane; Berkowitz, Gerald A.

1989-01-01

33

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...

34

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...

35

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

PubMed Central

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

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

2012-01-01

36

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

PubMed

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

Kuti, J O; Kuti, H O

1999-01-01

37

Localization of a protein, immunologically similar to a sucrose-binding protein from developing soybean cotyledons, on the plasma membrane of sieve-tube members of spinach leaves  

Microsoft Academic Search

Immunocytochemical studies using antibodies raised against a 62-kDa membrane protein isolated from developing soybean (Glycine max (L.) Merr.) cotyledons were performed on leaf tissue of spinach (Spinacia oleracea L.). This 62-kDa protein was labeled by 6?-deoxy-6?-(4-azido-2-hydroxy)-benzamidosucrose (HABS), a photoaffinity sucrose\\u000a analogue (K. G. Ripp et al., 1988, Plant Physiol.88, 1435–1445). Western-blot analysis of spinach plasma-membrane proteins indicated a cross-reactive polypeptide

Robert D. Warmbrodt; Thomas J. Buckhout; William D. Hitz

1989-01-01

38

Mechanism of lanthanum effect on chlorophyll of spinach  

Microsoft Academic Search

The mechanism of La3+ effect on chlorophyll (chl) of spinach in solution culture has been studied. The results show that La3+ can obviously promote growth, increase chlorophyll contents and photosynthetic rate of spinach. La3+ may substitute Mg2+ for chlorophyll formation of spinach when there is no Mg2+ in solution. La3+ improves significantly PSII formation and enhances electron transport rate of

Fashui Hong; Zhenggui Wei; Guiwen Zhao

2002-01-01

39

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 ...

40

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

41

cDNA sequence and heterologous expression of monomeric spinach pullulanase: multiple isomeric forms arise from the same polypeptide.  

PubMed Central

The spinach pullulanase gene was cloned and sequenced using peptide sequences of the purified enzyme as a starting point and employing PCR techniques and cDNA library screening. Its open reading frame codes for a protein of 964 amino acids which represents a precursor of the pullulanase. The N-terminal transit peptide consists of 65 amino acids, and the mature protein, comprising 899 amino acids, has a calculated molecular mass of 99kDa. Pullulanase is a member of the alpha-amylase family. In addition to a characteristic catalytic (beta/alpha)8-barrel domain, it contains a domain, F, that is specific for branching and debranching enzymes. Pullulanase cDNA was expressed in Escherichia coli, and the purified protein was compared with the enzyme from spinach leaves. Identity of the two proteins was confirmed in terms of catalytic properties, N-terminal amino acid sequences and molecular masses. The pullulanase produced by E. coli showed the same microheterogeneity as the spinach leaf enzyme: it could be resolved into two substrate-induced forms by electrophoresis in amylopectin-containing polyacrylamide gels, and, in the absence of substrate, into several free forms (charge isomers) by isoelectric focusing or chromatofocusing. Rechromatofocusing of single free forms resulted in the originally observed pattern of molecular forms. However, heterogeneity of the protein disappeared on isoelectric focusing under completely denaturing conditions when only one protein band was observed. Post-translational modifications such as glycosylation and phosphorylation could be excluded as potential explanations for the protein heterogeneity. Therefore the microheterogeneity of spinach leaf pullulanase results from neither genetic variation nor post-translational modifications, but is a property of the single unmodified gene product. The different interconvertible forms of the pullulanase represent protein populations of different tertiary structure of the same polypeptide. PMID:9560325

Renz, A; Schikora, S; Schmid, R; Kossmann, J; Beck, E

1998-01-01

42

Choline Oxidation by Intact Spinach Chloroplasts 1  

PubMed Central

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

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

1988-01-01

43

Studies of a New Fusarium Wilt of Spinach in Texas.  

E-print Network

Savoy, Victoria, Im- proved Thick Leaved (Viroflay), and Long Season. None of these vari- eties, however, showed any more resistance than the other. On the other hand, New Zealand spinach (Tetragonia expansa) proved to be completely resistant...

Taubenhaus, J. J. (Jacob Joseph)

1926-01-01

44

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

PubMed

Spinach seeds (Spinacia oleracea L.) given massive doses of gamma-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. PMID:16659421

Rose, R; Possingham, J

1976-01-01

45

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±0.12min with a z-value of 13.92±0.87°C. The calculated activation energy value was 162±11kJ/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 120-180s), the blanching of spinach in water at 100°C for 120-180s 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

46

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

47

Greenhouse spinach production in a NFT system.  

PubMed

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

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

1996-12-01

48

Photoperiodic Control of Gibberellin Metabolism in Spinach 1  

PubMed Central

[3H]GA20 applied to spinach plants (Spinacia oleracea L.) was metabolized to several products. Two of these were identified by combined gasliquid chromatography-radio counting as [3H]GA29 and [3H]3-epi-GA1. Inasmuch as both GA20 and GA29 are endogenous gibberellins in spinach (Metzger, Zeevaart 1980 Plant Physiol 65: 623-626), it was concluded that the conversion of GA20 to GA29 is a natural process. However, 3-epi-GA1 was not detected in extracts of spinach shoots analyzed by combined gas chromatography-mass spectrometry. This indicates that the conversion of exogenous [3H]GA20 to [3H]3-epi-GA1 may be an artifact. Long-day pretreatment of spinach shoots caused a 2-fold increase in the rate of [3H]GA20 metabolism over the rate of metabolism in plants maintained under short-day conditions. Furthermore, [3H]GA29 accumulated more rapidly under long than under short days, whereas photoperiodic treatment had no effect on the accumulation of [3H]3-epi-GA1. Thus, the long-day-induced increase in the level of endogenous GA29 in spinach shoots (Metzger, Zeevaart 1980 Plant Physiol 66: 844-846) appears to be the result of an increased capability to convert GA20 to GA29. PMID:16662194

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

1982-01-01

49

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

50

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...

51

Flow Cytometry of Spinach Chloroplasts 1  

PubMed Central

Intact spinach (Spinacia oleracea) chloroplasts, thylakoid membranes, and inside-out or right-side-out thylakoid vesicles have been characterized by flow cytometry with respect to forward angle light scatter, right angle light scatter, and chlorophyll fluorescence. Analysis of intact chloroplasts with respect to forward light scatter and the chlorophyll fluorescence parameter revealed the presence of truly “intact” and “disrupted” chloroplasts. The forward light scatter parameter, normally considered to reflect object size, was instead found to reflect the particle density. One essential advantage of flow cytometry is that additional parameters such as Ricinus communis agglutinin (linked to fluorescein isothiocyanate) fluorescence can be determined through logical conditions placed on bit-maps, amounting to an analytical purification procedure. In the present case, chloroplast subpopulations with fully preserved envelopes, thylakoid membrane, and inside-out or right-side-out thylakoid membranes vesicles can be distinguished. Flow cytometry is also a useful tool to address the question of availability of glycosyl moities on the membrane surfaces if one keeps in mind that organelle-to-organelle interactions could be partially mediated through a recognition process. A high specific binding of R. communis agglutinin and peanut lectin to the chloroplast envelope was detected. This showed that galactose residues were exposed and accessible to specific lectins on the chloroplast surface. No exposed glucose, fucose, or mannose residues could be detected by the appropriate lectins. Ricin binding to the intact chloroplasts caused a strong aggregation. Disruption of these aggregates by resuspension or during passage in the flow cytometer induced partial breakage of the chloroplasts. Only minor binding of R. communis agglutinin and peanut lectin to the purified thylakoid membranes was detected; the binding was found to be low for both inside-out and right-side-out vesicles of the thylakoid membranes. Images Figure 1 Figure 1 Figure 1 PMID:16653090

Schröder, Wolfgang P.; Petit, Patrice X.

1992-01-01

52

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

PubMed Central

Both reduced and oxidized ascorbate (AA and DHA) are present in the aqueous phase of the extracellular space, the apoplast, of spinach (Spinacia oleracea L.) leaves. Fumigation with 0.3 [mu]L L-1 of ozone resulted in ozone uptake by the leaves close to 0.9 pmol cm-2 of leaf surface area s-1. Apoplastic AA was slowly oxidized by ozone. The initial decrease of apoplastic AA was <0.1 pmol cm-2 s-1. The apoplastic ratio of AA to (AA + DHA) decreased within 6 h of fumigation from 0.9 to 0.1. Initially, the concentration of (AA + DHA) did not change in the apoplast, but when fumigation was continued, DHA increased and AA remained at a very low constant level. After fumigation was discontinued, DHA decreased very slowly in the apoplast, reaching control level after 70 h. The data show that insufficient AA reached the apoplast from the cytosol to detoxify ozone in the apoplast when the ozone flux into the leaves was 0.9 pmol cm-2 s-1. The transport of DHA back into the cytosol was slower than AA transport into the apoplast. No dehydroascorbate reductase activity could be detected in the apoplast of spinach leaves. In contrast to its extracellular redox state, the intracellular redox state of AA did not change appreciably during a 24-h fumigation period. However, intracellular glutathi-one became slowly oxidized. At the beginning of fumigation, 90% of the total glutathione was reduced. Only 10% was reduced after 24-h exposure of the leaves to 0.3 [mu]L L-1 of ozone. Necrotic leaf damage started to become visible when fumigation was extended beyond a 24-h period. A close correlation between the extent of damage, on the one hand, and the AA content and the ascorbate redox state of whole leaves, on the other, was observed after 48 h of fumigation. Only the youngest leaves that contained high ascorbate concentrations did not exhibit necrotic leaf damage after 48 h. PMID:12231749

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

1993-01-01

53

First report of Tobacco rattle virus in spinach in California.  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

54

Isolation and Characterization of Phosphatidyl Choline from Spinach Leaves.  

ERIC Educational Resources Information Center

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

Devor, Kenneth A.

1979-01-01

55

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.

56

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.

57

Plug-and-Play Fluorophores Extend the Spectral Properties of Spinach  

PubMed Central

Spinach and Spinach2 are RNA aptamers that can be used for the genetic encoding of fluorescent RNA. Spinach2 binds and activates the fluorescence of (Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one (DFHBI), allowing the dynamic localizations of Spinach2-tagged RNAs to be imaged in live cells. The spectral properties of Spinach2 are limited by DFHBI, which produces fluorescence that is bluish-green and is not optimized for filters commonly used in fluorescence microscopes. Here we characterize the structural features that are required for fluorophore binding to Spinach2 and describe novel fluorophores that bind and are switched to a fluorescent state by Spinach2. These diverse Spinach2–fluorophore complexes exhibit fluorescence that is more compatible with existing microscopy filter sets and allows Spinach2-tagged constructs to be imaged with either GFP or YFP filter cubes. Thus, these “plug-and-play” fluorophores allow the spectral properties of Spinach2 to be altered on the basis of the specific spectral needs of the experiment. PMID:24393009

2014-01-01

58

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

59

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

60

Enzyme-assisted extraction of stabilized chlorophyll from spinach.  

PubMed

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

Özkan, Gülay; Ersus Bilek, Seda

2015-06-01

61

Comparative uptake of enteric viruses into spinach and green onions.  

PubMed

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

Hirneisen, Kirsten A; Kniel, Kalmia E

2013-03-01

62

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

63

Translation of mRNAs for subunits of chloroplast coupling factor 1 in spinach  

PubMed Central

The chloroplast coupling factor 1 consists of five nonidentical subunits, three of which (?, ?, and ? subunits) have been shown in several laboratories to be synthesized within chloroplasts. The site of synthesis of the remaining two (? and ? subunits) was investigated by analyzing products directed by spinach leaf RNAs in wheat germ and reticulocyte translation systems in vitro. It was found that poly(A)+ RNA directs the synthesis of two distinct polypeptides, one of which is immunochemically related to the ? subunit but is 4,000 daltons larger. The other shares antigenic sites with the ? subunit but is 8,000 daltons larger. When wheat germ or reticulocyte translation systems were programmed with RNAs from purified chloroplasts, the only products related to CF1 that we could detect were a putative precursor of ?, 2,000 daltons larger than the mature subunit, and some smaller polypeptides, which appear to be incomplete translation products of ?. From these results it appears likely that the ? and ? subunits are synthesized in the cytoplasm as larger precursors and that ? is synthesized within the chloroplast as a precursor. Images PMID:16593240

Watanabe, Akira; Price, Carl A.

1982-01-01

64

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...

65

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 ...

66

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

67

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

Microsoft Academic Search

Proximate composition and mineral content of raw and cooked leaves of two edible tree spinach species (Cnidoscolus chayamansa and C. aconitifolius), known locally as ‘chaya’, were determined and compared with that of a traditional green vegetable, spinach (Spinicia oleraceae). Results of the study indicated that the edible leafy parts of the two chaya species contained significantly (p0.05) differences were found

J. O. Kuti; H. O. Kuti

1999-01-01

68

Effects of Oxalic Acid on Availability of Zinc from Spinach Leaves and Zinc Sulfate to Rats  

Microsoft Academic Search

Some effects of dietary oxalic acid on availability of zinc from organic and inorganic sources were assessed. Male rats fed zinc- deficient diets with ana without added sodium oxalate were orally dosed once with either 66Zn-labeled spinach leaves or 65Zn-labeled zinc sulfate. Spinach plants (Spinacia olerácea,var. \\

ROSS M. WELCH; WILLIAM A. HOUSE

2010-01-01

69

Behavior of Escherichia coli O157:H7 on damaged leaves of spinach, lettuce, cilantro, and parsley stored at abusive temperatures.  

PubMed

Recent foodborne illness outbreaks associated with the consumption of leafy green produce indicates a need for additional information on the behavior of pathogenic bacteria on these products. Previous research indicates that pathogen growth and survival is enhanced by leaf damage. The objective of this study was to compare the behavior of Escherichia coli O157:H7 on damaged leaves of baby Romaine lettuce, spinach, cilantro, and parsley stored at three abusive temperatures (8, 12, and 15 degrees C). The damaged portions of leaves were inoculated with approximately 10(5) CFU E. coli O157:H7 per leaf. The pathogen grew on damaged spinach leaves held for 3 days at 8 and 12 degrees C (P < 0.05), with the population increasing by 1.18 and 2.08 log CFU per leaf, respectively. E. coli O157:H7 did not grow on damaged Romaine leaves at 8 or 12 degrees C, but growth was observed after 8 h of storage at 15 degrees C, with an increase of less than 1.0 log. Growth of E. coli O157:H7 on Romaine lettuce held at 8 or 12 degrees C was enhanced when inocula were suspended in 0.05% ascorbic acid, indicating the possibility of inhibition by oxidation reactions associated with tissue damage. Damaged cilantro and Italian parsley leaves held at 8 degrees C for 4 days did not support the growth of E. coli O157:H7. Behavior of the pathogen in leaf extracts differed from behavior on the damaged tissue. This study provides evidence that the damaged portion of a leafy green is a distinct growth niche that elicits different microbial responses in the various types of leafy greens. PMID:20132665

Khalil, Rowaida K; Frank, Joseph F

2010-02-01

70

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.

71

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

PubMed

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

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

2013-12-01

72

Nucleotide sequence of a spinach chloroplast proline tRNA.  

PubMed Central

The nucleotide sequence of a spinach chloroplast proline tRNA (sp. chl. tRNApro) has been determined. This tRNA shows more overall homology to phage T4 proline tRNA (61% homology) than to eukaryotic proline tRNAs (53% homology) or mitochondrial proline tRNAs (36-49% homology). Sp. chl. tRNApro, like all other chloroplast tRNAs sequenced, contains a methylated GG sequence in the dihyrouridine loop and lacks unusual structural features which have been found in many mitochondrial tRNAs. PMID:7079185

Francis, M; Kashdan, M; Sprouse, H; Otis, L; Dudock, B

1982-01-01

73

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.

74

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

PubMed Central

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

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

1995-01-01

75

The nucleotide sequence of spinach chloroplast tryptophan transfer RNA.  

PubMed Central

Spinach chloroplast tRNATrp, purified by column chromatography and two-dimensional gel electrophoresis, has been sequenced using in vitro labeling techniques. The sequence is : pG-C-G-C-U-C-U-U-A-G-U-U-C-A-G-U-U-C-Gm-G-D-A-G-A-A-C-m2G-psi-G-G-G-psi-C-U-C-A-A*-A-A-C-C-C-G-A-U-G-N-C-G-U-A-G-G-T-psi-C-A-A-G-U-C-C-U-A-C-A-G-A-G-C-G-U-G -C-C-AOH. Like the E. coli suppressor tRNA psu+UGA which translates both the opal terminator codon U-G-A and the tryptophan codon U-G-G, spinach chloroplast tRNATrp has C-C-A as an anticodon and contains an A-U pair in the D-stem. Images PMID:6907845

Canaday, J; Guillemaut, P; Gloeckler, R; Weil, J H

1981-01-01

76

The stereospecificity, purification, and characterization of an NADH-ferricyanide reductase from spinach leaf plasma membrane  

Microsoft Academic Search

Summary The stereospecificity of NADH-ferricyanide reductase activities in the inner mitochondrial membrane, peroxisomal membrane, plasma membrane and tonoplast are all specific for the ß-hydrogen of NADH whereas the reductases in the ER, the Golgi and the outer mitochondrial membrane are a-specific. This shows unequivocally that the NADH-ferricyanide activity in the plasma membrane is not caused by ER contamination. In all

I. M. Møller; K. M. Fredlund; A. Bérczi

1995-01-01

77

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

PubMed

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

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

2012-04-01

78

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

79

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 1.9×105 to 6.5×104 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

80

Surface and internalized Escherichia coli O157:H7 on field-grown spinach and lettuce treated with spray-contaminated irrigation water.  

PubMed

Numerous field studies have revealed that irrigation water can contaminate the surface of plants; however, the occurrence of pathogen internalization is unclear. This study was conducted to determine the sites of Escherichia coli O157:H7 contamination and its survival when the bacteria were applied through spray irrigation water to either field-grown spinach or lettuce. To differentiate internalized and surface populations, leaves were treated with a surface disinfectant wash before the tissue was ground for analysis of E. coli O157:H7 by direct plate count or enrichment culture. Irrigation water containing E. coli O157:H7 at 10(2), 10(4), or 10(6) CFU/ml was applied to spinach 48 and 69 days after transplantation of seedlings into fields. E. coli O157:H7 was initially detected after application on the surface of plants dosed at 10(4) CFU/ml (4 of 20 samples) and both on the surface (17 of 20 samples) and internally (5 of 20 samples) of plants dosed at 10(6) CFU/ml. Seven days postspraying, all spinach leaves tested negative for surface or internal contamination. In a subsequent study, irrigation water containing E. coli O157:H7 at 10(8) CFU/ml was sprayed onto either the abaxial (lower) or adaxial (upper) side of leaves of field-grown lettuce under sunny or shaded conditions. E. coli O157:H7 was detectable on the leaf surface 27 days postspraying, but survival was higher on leaves sprayed on the abaxial side than on leaves sprayed on the adaxial side. Internalization of E. coli O157:H7 into lettuce leaves also occurred with greater persistence in leaves sprayed on the abaxial side (up to 14 days) than in leaves sprayed on the adaxial side (2 days). PMID:20537256

Erickson, Marilyn C; Webb, Cathy C; Diaz-Perez, Juan Carlos; Phatak, Sharad C; Silvoy, John J; Davey, Lindsey; Payton, Alison S; Liao, Jean; Ma, Li; Doyle, Michael P

2010-06-01

81

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 prey—the "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

82

Rapid disruption of nitrogen metabolism and nitrate transport in spinach plants deprived of sulphate.  

PubMed

Hydroponically grown spinach plants were deprived of an external source of sulphate after an initial period when the S-supply was sufficient. The time-course of events following this treatment was monitored. The first responses were found in the uptake and translocation of NO(3)(-) and the uptake of SO(4)(2-). The former declined by approximately 50%, the effect being most significant at higher [NO(3)(-)](ext.) while the latter increased 6-fold over a 4 d period. Growth in the absence of external SO(4)(2-) resulted in exhaustion of internal SO(4)(2-) pools, the effect being seen first in roots, then in young leaves and, after a marked delay, in mature leaves. In young leaves, there were dramatic increases in the [NO(3)(-)] and the content of arginine in the first 2 d of S-deprivation. The concentration of glutamine, the most abundant amino acid in S-sufficient conditions, also more than doubled in S-deficient young leaves. The changes in arginine levels were also found in older leaves, but the change in glutamine level was not seen. Assays of nitrate reductase activity (NRA) and nitrate reductase (NR) mRNA from young leaves of S-replete and S-deprived plants revealed a divergence in activity and content only late in the experiments (between days 4 and 8) when results were expressed on a unit leaf basis. However, there were also time-dependent changes in the protein content that kept the specific activities (NRA:protein and RNA:protein) more or less unchanged. The results imply that the impact of S-deficiency on N-utilization are more sensitively monitored by simple measurements of the chemical composition of young leaves than by measurements of NRA or NR transcript abundance. They also suggest that protein synthesis in young leaves is strongly dependent on a continuous supply of SO(4)(2-) from outside the plant. PMID:11181720

Prosser, I M; Purves, J V; Saker, L R; Clarkson, D T

2001-01-01

83

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

84

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.

85

Formation of Glycolate by a Reconstituted Spinach Chloroplast Preparation 1  

PubMed Central

A reconstituted preparation requiring fructose 6-phosphate, transketolase, triphosphopyridine nucleotide, ferredoxin, fragmented spinach chloroplasts, and light capable of forming glycolate at rates of about 10 micromoles per milligram of chlorophyll per hour has been characterized. The glycolaldehyde-transketolase addition product could be substituted for fructose 6-phosphate and transketolase. The stoichiometry of the reaction was: 1 mole of fructose 6-phosphate consumed for each mole of glycolate and of reduced triphosphopyridine nucleotide produced. Evidence was presented indicating that glycolate formation was coupled to the photosystems of the photosynthetic electron transport chain. Synthesis of glycolate is envisaged as the result of either (a) a reaction between the upper two carbon atoms derived from fructose 6-phosphate and an uncharacterized oxidant generated by photosystem 2 or (b) hydrogen peroxide produced by the reoxidation of reduced triphos-phopyridine nucleotide or reduced ferredoxin by molecular oxygen. PMID:16657791

Shain, Y.; Gibbs, Martin

1971-01-01

86

Sulfur Dioxide Inhibition of Photosynthesis in Isolated Spinach Chloroplasts  

PubMed Central

Photosynthetic oxygen evolution by isolated spinach (Spinacia oleracea L.) chloroplasts approached complete inhibition in the presence of a 5 mm concentration of sulfur dioxide. A similar inhibition was observed in the presence of equimolar concentrations of bisulfite ions, suggesting a parallel mode of action. In contrast, an equimolar concentration of sulfite ions was markedly less inhibitory and sulfate ions caused negligible inhibition of apparent photosynthesis. The mode of action of sulfur dioxide and related sulfur anions in inhibiting photosynthesis was found to be essentially independent of direct hydrogen-ion effects. Supplements of inorganic pyrophosphate lessened the inhibition of oxygen evolution caused by sulfur dioxide and the sulfur anions. Sulfur dioxide and the sulfur anions were almost equally effective in inhibiting cyclic and noncyclic photophosphorylation in chloroplast suspensions. However, the extent of the inhibition of these photosynthetic reactions does not appear sufficient to account for the inhibition of photosynthetic oxygen evolution by sulfur dioxide. PMID:16659319

Silvius, John E.; Ingle, Morris; Baer, Charles H.

1975-01-01

87

200 BIOCHIMICAET BIOPHYS1CAACTA Thermoluminescence in spinach chlorophsts and in Chlorella  

E-print Network

200 BIOCHIMICAET BIOPHYS1CAACTA BBA Report BBA41165 Thermoluminescence in spinach chlorophsts. This thermoluminescence is observed both in normal and 3(3,4-dichlorophenyl)-l,l.dimethylurea.treated samples

Govindjee

88

Microbial antagonists of Escherichia coli O157:H7 on fresh-cut lettuce and spinach.  

PubMed

Fresh-cut lettuce and spinach can become contaminated with pathogens at numerous points from the field to the retail market. Natural microflora present on fresh produce may help reduce the pathogen load. The objective of this study was to isolate natural microflora from fresh-cut iceberg lettuce and baby spinach and to determine whether these bacteria were antagonistic toward Escherichia coli O157:H7. Samples were collected under conditions that mimicked actual practices between production and retail sale. Evidence of naturally occurring microorganisms on fresh lettuce (295 isolates) and spinach (200 isolates) and of possible antagonistic activity toward E. coli O157:H7 was documented. Inhibitory activity by several isolates was due to either acid production or antimicrobial peptides. Bacteria with inhibitory activity were isolated from every step in the processing and handling of the fresh-cut iceberg lettuce and baby spinach. PMID:19681287

Johnston, Michael A; Harrison, Mark A; Morrow, Ruth A

2009-07-01

89

Cyanogenic glycosides content in two edible leaves of tree spinach ( Cnidoscolus spp.)  

Microsoft Academic Search

The cyanogenic glycosides content (ranging from 0.79±0.2 to 14.79±0.4?g HCN equivalent\\/g fresh wt) of two edible tree spinach (Cnidoscolus chayamansa McVaugh and C. aconitifolius (P. Mill.) I.M. Johnston) leaves was quantitatively analyzed using enzymatic assay and UV-vis spectrum techniques. Both techniques equally show efficiency and reliability in assessing cyanogen content in tree spinach vegetable tissues. Cyanogenic glycoside concentration was significantly

Joseph O. Kuti; Hima B. Konoru

2006-01-01

90

Uptake of l-Ascorbate by Intact Spinach Chloroplasts.  

PubMed

Uptake of l-[1-(14)C]ascorbate by intact ascorbate-free spinach (Spinacia oleracea L. cv Vital(r)) 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 K(m) 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 20 degrees C). 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 V(max) but did not change the K(m) 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, E; Burkert, A; Hofmann, M

1983-09-01

91

Purification of gibberellin sub 53 -oxidase from spinach  

SciTech Connect

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

Wilson, T.M.; Zeevaart, J.A.D. (Michigan State Univ., East Lansing (USA))

1989-04-01

92

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

PubMed

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

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

2008-08-01

93

Growing and processing conditions lead to changes in the carotenoid profile of spinach.  

PubMed

This study aimed to evaluate the influence of different light regimens during spinach cultivation on the isomeric composition of ?-carotene. Irradiation with a halogen lamp, which has a wavelength spectrum close to that of daylight, was used to mimic field-grown conditions. The additional use of optical filters was established as a model system for greenhouse cultivation. Field-grown model systems led to a preferential increase of 9-cis-?-carotene, whereas 13-cis-?-carotene was just formed at the beginning of irradiation. Additionally 9,13-di-cis-?-carotene decreased significantly in the presence of energy-rich light. Isomerization of ?-carotene was strongly suppressed during irradiation in greenhouse-grown model systems and led to significant differences. These results were verified in biological samples. Authentic field-grown spinach (Spinacia oleracea L.) showed among changes of other isomers a significantly higher level of 9-cis-isomers (7.52 ± 0.14%) and a significantly lower level of 9,13-di-cis-isomers (0.25 ± 0.03%) compared to authentic greenhouse-grown spinach (6.49 ± 0.11 and 0.76 ± 0.05%). Almost all analyzed commercial spinach samples (fresh and frozen) were identified as common field-grown cultivation. Further investigations resulted in a clear differentiation of frozen commercial samples from fresh spinach, caused by significantly higher levels of 13-cis- and 15-cis-?-carotene as a result of industrial blanching processes. PMID:24831992

Heymann, Thomas; Westphal, Lore; Wessjohann, Ludger; Glomb, Marcus A

2014-05-28

94

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

95

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

E-print Network

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

Weiblen, George D

96

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

E-print Network

protein of spinach photosystem II by Fourier transform infrared spectroscopy H. Zhanga,1 , Y. Yamamotob of the extrinsic 16 kDa protein of the spinach photosystem II (OEC16) were characterized in solution between 25 Elsevier Science B.V. All rights reserved. Keywords: FTIR; OEC16; Secondary structure; Photosystem II 1

Carpentier, Robert

97

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

ERIC Educational Resources Information Center

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

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

2004-01-01

98

Effect of increasing offer level of water spinach (Ipomoea aquatica) on intake, growth and digestibility coefficients of rabbits  

Microsoft Academic Search

Twelve New Zealand White rabbits with an initial live weight of 897 ± 95.2 g were allocated to a randomized block design to study the effect of different levels of water spinach (Ipomoea aquatica) (8, 10, 12, 14, 16 and 18% of live weight in DM). The water spinach was taken from the first and second harvests of plants established

Pok Samkol; T R Preston; J Ly

99

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.

Hansing, Rebecca

100

Sequence of the genes for tRNACys and tRNAAsp from spinach chloroplasts.  

PubMed Central

We have determined the map location and primary structure of two fragments of spinach chloroplast DNA which encompass the genes for tRNACysGCA and tRNAAspGUC. Identification of the genes for these two RNA species is based on the sequence of their anticodon triplets and on a comparison of the sequences with those of the equivalent tRNAs from Escherichia coli. Each gene occurs only once on the spinach chloroplast genome and neither contains an intervening sequence. Hybridization of the restriction fragments carrying these genes to chloroplast tRNA showed that both genes are transcribed in vivo. Images PMID:6324088

Holschuh, K; Bottomley, W; Whitfeld, P R

1983-01-01

101

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

PubMed

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

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

2013-12-01

102

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 et al., 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 Kühn et al. (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 et al., 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

103

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...

104

Microdissection and painting of the Y chromosome in spinach (Spinacia oleracea).  

PubMed

Spinach has long been used as a model for genetic and physiological studies of sex determination and expression. Although trisomic analysis from a cross between diploid and triploid plants identified the XY chromosome as the largest chromosome, no direct evidence has been provided to support this at the molecular level. In this study, the largest chromosomes of spinach from mitotic metaphase spreads were microdissected using glass needles. Degenerate oligonucleotide primed polymerase chain reaction was used to amplify the dissected chromosomes. The amplified products from the Y chromosome were identified using the male-specific marker T11A. For the first time, the largest spinach chromosome was confirmed to be a sex chromosome at the molecular level. PCR products from the isolated chromosomes were used in an in situ probe mixture for painting the Y chromosome. The fluorescence signals were mainly distributed on all chromosomes and four pair of weaker punctate fluorescence signal sites were observed on the terminal region of two pair of autosomes. These findings provide a foundation for the study of sex chromosome evolution in spinach. PMID:23381038

Deng, Chuan-Liang; Qin, Rui-Yun; Cao, Ying; Gao, Jun; Li, Shu-Fen; Gao, Wu-Jun; Lu, Long-Dou

2013-07-01

105

Examination of the quality of spinach leaves using1 hyperspectral imaging technique2  

E-print Network

be defined as any fresh fruit or vegetable that has been physically4 modified from its original state (by supervision of quality deterioration in ready to use leafy spinach during storage4 (Spinacia oleracea). Two in the laboratory and after7 two days of storage; b) second set of samples was kept at 10°C (E-10); the8

Boyer, Edmond

106

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

E-print Network

stored leaves appeared to yield more and higher molecular weight DNA than any other treatment. In contrast, juniper leaves stored in 100 and 95% ethanol yielded more and higher molecular weight DNA than 70Phytologia (December 2011) 93(3) 283 SEVENTEEN YEARS STORAGE OF JUNIPER AND SPINACH LEAVES

Adams, Robert P.

107

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

108

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

109

Leaf Modeling and Constrained Leaf Morphing in Leaf Space Saurabh Garg1  

E-print Network

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

Leow, Wee Kheng

110

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

111

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

PubMed

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

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

2014-01-01

112

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

113

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

114

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

...designated phytosanitary measures will be sufficient to mitigate the risks of introducing or disseminating plant pests or noxious weeds via the importation of fresh celery, arugula, and spinach from Colombia. DATES: Effective Date: May 18, 2012. FOR...

2012-05-18

115

Understanding the photophysics of the spinach-DFHBI RNA aptamer-fluorogen complex to improve live-cell RNA imaging.  

PubMed

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

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

2013-12-18

116

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

PubMed Central

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

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

2014-01-01

117

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 (0.174–3.993ppm) 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

118

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 0.25–4‰ 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

119

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

120

Photoinhibition of photosystem I is accelerated by dimethyldithiocarbamate, an inhibitor of superoxide dismutase, during light-chilling of spinach leaves  

Microsoft Academic Search

In vivo photoinhibition of photosystem I (PS I) was investigated at chilling temperature using the leaves of the chilling-resistant spinach plant treated with an inhibitor of superoxide dismutase, diethyldithiocarbamate (DDC). When spinach leaves were treated with DDC during chilling at 4 °C for 12 h with a light intensity of 120 ?molm?2s?1, the activity of PS I and the content

Hong Jin Hwang; Jin-Hong Kim; Young-Jae Eu; Byoung Yong Moon; Sung Ho Cho; Choon-Hwan Lee

2004-01-01

121

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

122

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

123

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

PubMed

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

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

1974-10-01

124

Structure Prediction of Dihydroflavonol 4- Reductase and Anthocyanidin Synthase from Spinach  

PubMed Central

Spinach is an important dietary vegetable associated with beneficial health effects. Flavonoids have various biological activities such as antioxidant, antibacterial, and anticancer effect Flavonoid including anthocyanin provides brilliant and colored pigments in different plant tissues. Anthocyanidin synthase and dihydroflavonol 4-reductase are responsible for anthocyanin biosynthesis. They contributed in plant protection against UV-B radiation, microbial and herbivore pathogens. A 3D structures of anthocyanidin synthase and dihydroflavonol 4-reductase from spinach are constructed in this study through homology modeling. The homology modeling is done by using the MODELLER 9v7 software. The energy of models was minimized by applying molecular mechanics method. The root mean square deviation (RMSD) for C atoms between the template and the homology-modeled structures was estimated by CE program. The final models were assessed by PROCHECK and WHATCHECK which showed that the final refined models are reliable. PMID:21364828

Sahay, Archna; Shakya, Madhvi

2010-01-01

125

Characterization of a spinach gene responsive to low temperature and water stress  

Microsoft Academic Search

The characterization of a cDNA for an 85 kDa spinach protein, CAP85 (cold acclimation protein) that is responsive to cold acclimation and water stress is described. Both transcript and protein levels are increased during cold acclimation and water stress. A novel characteristic of CAP85 is the presence of an 11 amino acid, lysine-rich repeat, common to Group 2 LEAs (late

Lisa G. Neven; Dale W. Haskell; Andrea Hofig; Qui-Bao Li; Charles L. Guy

1993-01-01

126

Sexual modification of female spinach seeds ( Spinacia oleracea L.) by irradiation with ion particles  

Microsoft Academic Search

The female seeds of a spinach plant (Spinacia orelacea L.) were exposed to He (12.5 MeV\\/n) and C (18.3 MeV\\/n) ions in order to investigate the effects of ion particles on sex expression. He ions did not affect germination rates or flowering at doses up to 50 Gy. C ions did not affect germination rates or flowering at doses up

F. Komai; N. Shikazono; A. Tanaka

2003-01-01

127

In vitro high frequency plant regeneration from hypocotyl and root segments of spinach by organogenesis  

Microsoft Academic Search

An efficient protocol for spinach (Spinacia oleracea L.) plant regeneration from hypocotyl and root segments was established. When the sub-apical hypocotyl and tip-free root segments were cultured on Murashige & Skoog (1962)-based medium containing high concentrations of indole-3-acetic acid (85.62 µM) and gibberellic acid (100 µM), more than 75% and 90% of the hypocotyl and root explants, respectively, formed shoots.

Xing-guo Xiao; Michel Branchard

1995-01-01

128

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

Microsoft Academic Search

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

Doris Foehse; A. Jungk

1983-01-01

129

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

Microsoft Academic Search

Polyphenol oxidase activity (E.C. 1.14,18.1) has been found in two enzyme species isolated from thylakoid membranes of spinach chloroplasts. The proteins were released from the membrane by sonication and purified >900-fold by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzymes appear to be the tetramer and monomer of a subunit with a molecular weight of 42,500 as determined

J. H. Golbeck; K. V. Cammarata

1981-01-01

130

?-Cyanoalanine Synthase Is a Mitochondrial Cysteine Synthase-Like Protein in Spinach and Arabidopsis1  

PubMed Central

?-Cyano-alanine synthase (CAS; EC 4.4.1.9) plays an important role in cyanide metabolism in plants. Although the enzymatic activity of ?-cyano-Ala synthase has been detected in a variety of plants, no cDNA or gene has been identified so far. We hypothesized that the mitochondrial cysteine synthase (CS; EC 4.2.99.8) isoform, Bsas3, could actually be identical to CAS in spinach (Spinacia oleracea) and Arabidopsis. An Arabidopsis expressed sequence tag database was searched for putative Bsas3 homologs and four new CS-like isoforms, ARAth;Bsas1;1, ARAth;Bsas3;1, ARAth;Bsas4;1, and ARAth;Bsas4;2, were identified in the process. ARAth;Bsas3;1 protein was homologous to the mitochondrial SPIol;Bsas3;1 isoform from spinach, whereas ARAth;Bsas4;1 and ARAth;Bsas4;2 proteins defined a new class within the CS-like proteins family. In contrast to spinach SPIol;Bsas1;1 and SPIol;Bsas2;1 recombinant proteins, spinach SPIol;Bsas3;1 and Arabidopsis ARAth;Bsas3;1 recombinant proteins exhibited preferred substrate specificities for the CAS reaction rather than for the CS reaction, which identified these Bsas3 isoforms as CAS. Immunoblot studies supported this conclusion. This is the first report of the identification of CAS synthase-encoding cDNAs in a living organism. A new nomenclature for CS-like proteins in plants is also proposed. PMID:10889265

Hatzfeld, Yves; Maruyama, Akiko; Schmidt, Ahlert; Noji, Masaaki; Ishizawa, Kimiharu; Saito, Kazuki

2000-01-01

131

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

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

1992-01-01

132

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

133

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...

134

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.

135

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

E-print Network

, by the deposition of more cellulose in fiber secondary cell walls as directly demonstrated through image analysis hypothesized that SPS also had a specific metabolic role within the fiber itself by promoting the synthesis of sucrose, which is thought to be a required substrate for cellulose synthesis. A family of transgenic

Strauss, Richard E.

136

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

Sack, Lawren

137

Leaf conductance and carbon gain under salt-stressed conditions  

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

138

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...

139

Spinach Cultigen Variation for Tissue Carotenoid Concentrations Influences Human Serum Carotenoid Levels and Macular Pigment Optical Density Following a 12Week Dietary Intervention  

Microsoft Academic Search

Increasing intakes of carotenoid-rich plant foods can increase serum carotenoid concentrations and macular pigment optical density (MPOD) in most, but not all, individuals. Research objectives for this study were to (1) characterize tissue lutein (L) and ?-carotene (BC) concentrations in carotenoid-rich spinach (Spinacia oleracea L.) cultigens and (2) determine serum carotenoid and MPOD responses in human subjects consuming spinach cultigens

Dean A. Kopsell; David E. Kopsell; Adam J. Wenzel; Catherine Gerweck; Joanne Curran-Celentano

2006-01-01

140

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

141

LEAF MARGIN INFLORESCENCE  

E-print Network

image. Consider submitting multiple images, each one focused ILLUSTRATION OFTHEVARIOUS PLANT PARTS USED{ 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

142

Measurement and Preservation of the in Vivo Activation of Ribulose 1,5-Bisphosphate Carboxylase in Leaf Extracts 1  

PubMed Central

Photosynthetic carbon fixation is regulated in the chloroplast by the amount of ribulose 1,5-bisphosphate carboxylase which is activated. The activated carboxylase was preserved in detached leaves (barley, maize, soybean, spinach, wheat) for 90 min when stored on ice. With leaf extracts stored at 2°C, the amount of activated enzyme, representing that originally in the leaf, as well as the fully activated enzyme, formed by incubation of leaf extracts with Mg2+ and bicarbonate, both slowly declined in activity. However, for each activity this decline was proportional such that the ratio (percent activation) appeared constant. No change was observed in activation of the enzyme during the brief time of leaf homogenization. Optimal conditions (Mg2+, incubation time) for measurement of leaf activation of ribulose bisphosphate carboxylase vary depending on the plant. 3-Phosphonoproprionate, a positive effector of the purified ribulose bisphosphate carboxylase and a metabolically inert analog of 2-phosphoglycolate, was used to examine what metabolic effectors might do to enzyme activation during leaf homogenization and preparation of the extract at 2° C. Activation under these conditions was not altered by 3-phosphonoproprionate. When 3-phosphonoproprionate was brushed on attached leaves or taken up by the transpiration stream of detached leaves, a considerable increase in activation of the carboxylase was measured. PMID:16662364

Perchorowicz, John T.; Raynes, Deborah A.; Jensen, Richard G.

1982-01-01

143

Characteristics of light-dependent inorganic carbon uptake by isolated spinach chloroplasts.  

PubMed

The light-dependent accumulation of radioactively labeled inorganic carbon in isolated spinach (Spinacia oleracea L.) chloroplasts was determined by silicone oil filtering centrifugation. Intact chloroplasts, dark-incubated 60 seconds at pH 7.6 and 23 degrees C with 0.5 millimolar sodium bicarbonate, contained 0.5 to 1.0 millimolar internal inorganic carbon. The stromal pool of inorganic carbon increased 5- to 7-fold after 2 to 3 minutes of light. The saturated internal bicarbonate concentration of illuminated spinach chloroplasts was 10- to 20-fold greater than that of the external medium. This ratio decreased at lower temperatures and with increasing external bicarbonate. Over one-half the inorganic carbon found in intact spinach chloroplasts after 2 minutes of light was retained during a subsequent 3-minute dark incubation at 5 degrees C. Calculations of light-induced stromal alkalization based on the uptake of radioactively labeled bicarbonate were 0.4 to 0.5 pH units less than measurements performed with [(14)C]dimethyloxazolidine-dione. About one-third of the binding sites on the enzyme ribulose 1,5-bisphosphate carboxylase were radiolabeled when the enzyme was activated in situ and (14)CO(2) bound to the activator site was trapped in the presence of carboxypentitol bisphosphates. Deleting orthophosphate from the incubation medium eliminated inorganic carbon accumulation in the stroma. Thus, bicarbonate ion distribution across the chloroplast envelope was not strictly pH dependent as predicted by the Henderson-Hasselbach formula. This finding is potentially explained by the presence of bound CO(2) in the chloroplast. PMID:16663542

Sicher, R C

1984-04-01

144

Identification of novel antimicrobial resistance genes from microbiota on retail spinach  

PubMed Central

Background Drug resistance genes and their mobile genetic elements are frequently identified from environmental saprophytic organisms. It is widely accepted that the use of antibiotics in animal husbandry selects for drug resistant microorganisms, which are then spread from the farm environment to humans through the consumption of contaminated food products. We wished to identify novel drug resistance genes from microbial communities on retail food products. Here, we chose to study the microbial communities on retail spinach because it is commonly eaten raw and has previously been associated with outbreaks of bacterial infections. Results We created metagenomic plasmid libraries from microbiota isolated from retail spinach samples. We identified five unique plasmids that increased resistance to antimicrobial drugs in the E. coli host. These plasmids were identified in E. coli that grew on plates that contained ampicillin (pAMP), aztreonam (pAZT), ciprofloxacin (pCIP), trimethoprim (pTRM), and trimethoprim-sulfamethoxazole (pSXT). We identified open reading frames with similarity to known classes of drug resistance genes in the DNA inserts of all 5 plasmids. These drug resistance genes conferred resistance to fluoroquinolones, cephalosporins, and trimethoprim, which are classes of antimicrobial drugs frequently used to treat human Gram negative bacterial infections. These results show that novel drug resistance genes are found in microbiota on retail produce items. Conclusions Here we show that microbiota of retail spinach contains DNA sequences previously unidentified as conferring antibiotic resistance. Many of these novel sequences show similarity to genes found in species of bacteria, which have previously been identified as commensal or saprophytic bacteria found on plants. We showed that these resistance genes are capable of conferring clinically relevant levels of resistance to antimicrobial agents. Food saprophytes may serve as an important reservoir for new drug-resistance determinants in human pathogens. PMID:24289541

2013-01-01

145

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

PubMed

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

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

2011-01-01

146

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

E-print Network

Committee: Dr, R. S. Halliwe11 In 1977 and again in 1978 fall planted spinach grown in the Winter Garden area of South Texas was severely affected by a virus disease. Several distinct sets of symptoms were noted in the field suggesting that more than one... were 0. 859 for the top fraction, 0. 793 for the middle fraction, and 0. 825 for the bottom fraction. ACKNOWLEDGEMENTS The author wishes to acknowledge his wife Barbara for her patience; Mrs. Peg Porterfield for her cheerful help; Dr. R. S...

Adams, Edward Blair

1979-01-01

147

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

Microsoft Academic Search

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-\\u000a d-ido-octulose are the active 8-carbon ketosugar intermediates of the L-type pentose pathway, it was proposed that they may also\\u000a be reactants in a modified Calvin–Benson–Bassham pathway reaction scheme. This investigation therefore initially focussed\\u000a only on the ido-epimer

John F. Williams; John K. MacLeod

2006-01-01

148

Factors affecting the quality of freeze-dried and compressed spinach  

E-print Network

of samples which had been compressed under 500- 2000 psi and those which had not. Ultra high compression does not cause detectable chemical change but most foods are difficult to rehydrate. Compression of dried foods also causes fragmentation which... that fresh spinach lost moisture when stored at 5 and 21'C. In sampling freshly harvested product over a period of several winter months it was also found that there was a definite increase in dry weight due to moisture loss brought about by the changing...

Wisakowsky, Eugene Edward

2012-06-07

149

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

PubMed

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

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

2014-02-01

150

Pendimethalin phytotoxicity and seedling weed control in Indian spinach ( Basella alba L.)  

Microsoft Academic Search

Pot experiments were carried out in a screenhouse to evaluate pendimethalin effectiveness in pre-emergence weed control in Indian spinach (Basella alba L.). In the first trial, pendimethalin was applied at higher doses (0.33, 0.66, 0.99, 1.32, 1.98kgaiha?1), while in the second trial, lower doses (0.066, 0.132, 0.198, 0.264, 0.330kgaiha?1) were used. The treatments were arranged in a completely randomized design

M. A. K Smith

2004-01-01

151

Short communication Leaf optical properties and photosynthetic leaf absorptances  

E-print Network

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

Durako, Michael J.

152

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

E-print Network

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

Minnesota, University of

153

A Thermistor Leaf Thermometer  

PubMed Central

An instrument is described which allows measurements of leaf temperature within about 0.3 C. It consists of a special thermistor probe, a small circuit box, and a standard ammeter. The circuit box can easily be fixed to the meter and contains a battery, which passes 0.3 milliampere through the thermistor, and also contains an integrated circuit amplifier, so that the meter reads 20 C full scale deflection, with ranges adjustable in 10 C steps. Calibration experiments show the superiority of the thermistor leaf thermometer to a thermocouple pressed onto a rubber surface with a resilience resembling that of a leaf. Images PMID:16657432

Linacre, E. T.; Harris, W. J.

1970-01-01

154

Four-Leaf Clover  

NSDL National Science Digital Library

Scientist-in-training Summer Praetorius has an unusual skillâshe 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 observationâa skill Praetorius uses to spot tiny shelled animals called foraminiferaâand 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

155

Sexual modification of female spinach seeds (Spinacia oleracea L.) by irradiation with ion particles.  

PubMed

The female seeds of a spinach plant (Spinacia orelacea L.) were exposed to He (12.5 MeV/n) and C (18.3 MeV/n) ions in order to investigate the effects of ion particles on sex expression. He ions did not affect germination rates or flowering at doses up to 50 Gy. C ions did not affect germination rates or flowering at doses up to 15 Gy, but a dose of 25 Gy resulted in many plants with morphological aberrations. When unexposed female plants were grown without cross-fertilization for 10 weeks after sowing, 5.6-14.3% of the plants produced anthers from female flowers. These sex-modified plants could self-pollinate and form seeds, which expressed only female organs. Conversely, gynomonoecious plants were induced from these female seeds by exposure to He ions (5-50 Gy) and C ions (5-25 Gy) without any difference in the rates of flowered progeny. Moreover, andromonoecious plants were induced from female seeds by exposure to He ions at 50 Gy. These results suggest that the sex of a spinach plant is expressed as a flexible phenotype, converging from female to gyno- and andromonoecy after exposure to ion particles. PMID:12789513

Komai, F; Shikazono, N; Tanaka, A

2003-04-01

156

The inhibitory action of SQDG (sulfoquinovosyl diacylglycerol) from spinach on Cdt1-geminin interaction.  

PubMed

A human replication initiation protein, Cdt1, is a central player in the cell cycle regulation of DNA replication, and geminin down-regulates Cdt1 function by direct binding. It has been demonstrated that Cdt1 hyperfunction resulting from Cdt1-geminin imbalance, for example, by geminin silencing with small interfering RNA, induces DNA re-replication and eventual cell death in some cancer-derived cell lines. We established a high throughput screening system based on a modified enzyme linked immunosorbent assay to identify compounds that interfere with human Cdt1-geminin binding. Using this system, we screened inhibitors from natural materials containing food components, and found that a glycolipid, sulfoquinovosyl diacylglycerol (SQDG), from spinach can inhibit Cdt1-geminin interaction in vitro, with 50% inhibition observed at concentrations of 1.79mug/ml. Other major glycolipids, such as monogalactosyl diacylglycerol (MGDG) and digalactosyl diacylglycerol (DGDG) from spinach, had no influence. Surface plasmon resonance analysis demonstrated that SQDG bound selectively to Cdt1, but did not interact with geminin. Using three-dimensional computer modeling analysis, SQDG was considered to interact with the geminin interaction interface on Cdt1, and the sulfate group of SQDG was assumed to make hydrogen bonds with the residue of Arg346 of Cdt1. These data could help to further understanding of the structure and function of Cdt1. In addition, SQDG could be a clue to developing more appropriate inhibitors of Cdt1-geminin interactions. PMID:18343230

Mizushina, Yoshiyuki; Takeuchi, Toshifumi; Hada, Takahiko; Maeda, Naoki; Sugawara, Fumio; Yoshida, Hiromi; Fujita, Masatoshi

2008-06-01

157

Low Temperature STM Manipulation and Spectroscopy of Chlorophyll-a Single Molecules from Spinach  

NASA Astrophysics Data System (ADS)

We interrogate single chlorophyll-a, a molecule produced from Spinach, on Cu(111) surface to check its mechanical stability and electronic properties using an ultra-high-vacuum low-temperature scanning-tunneling-microscope (UHV-LT-STM) at liquid helium temperatures. The measured results of isolated single chlorophyll-a molecules are then compared with that of self-assembled molecular layer. The tunneling I/V and dI/dV spectroscopy techniques are used to probe the electronic properties of the chlorophyll-a molecule with atomic precision (1). These spectroscopic investigations elucidate properties of the single molecule such as the band gap and additional molecular orbital states. Mechanical stability of the chlorophyll-a molecule is examined using lateral manipulation techniques with the STM tip (2). In this procedure, the STM tip is placed in close proximity to the molecule (just a few angstrom separation) to increase the tip-molecule interaction. Then the tip is laterally moved across the surface, which results in pulling of the chlorophyll-a molecule to relocate to the specific surface sites. The detailed molecule movement during this manipulation is directly monitored through the corresponding STM-tip height signals. Our results highlight that the Spinach molecule is a promising candidate for environmental friendly nano-electronic device applications. (1) F. Moresco et al, Phy. Rev. Lett. 86, 672-675, (2001) (2) S-W. Hla, K-H. Rieder, Ann. Phy. Chem. 54, 307-330, (2003)

Benson, Jessica J.; Iancu, Violeta; Deshpande, Aparna; Hla, Saw-Wai

2004-04-01

158

Single Molecule Manipulation and Spectroscopy of Chlorophyll-a from Spinach  

NASA Astrophysics Data System (ADS)

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

Benson, Jessica-Jones

2005-03-01

159

Identification and mutational analysis of the promoter for a spinach chloroplast transfer RNA gene.  

PubMed Central

A transcription extract from purified spinach chloroplast was used to test chloroplast DNA sequences for their function as promoter elements. Chloroplast tRNA genes are correctly transcribed in the extract by a soluble RNA polymerase, and precursor molecules are processed into mature tRNAs. Transcription of the spinach chloroplast tRNA2Met gene (trnM2) in vitro requires 5' upstream DNA sequences. Deletion of 5' DNA sequences with exonuclease Bal31 was used to establish the 5' boundary of the promoter region. This boundary is part of a DNA sequence with partial homology to the prokaryotic -35 region. Seventeen base pairs downstream from this sequence a DNA sequence occurs which is homologous to the prokaryotic -10 region. We used synthetic oligonucleotides fused to trnM2 5' deletion mutants to create insertions, deletions and base substitutions in these regions. Internal deletion mutants demonstrated that the -10 promoter element is also required for transcription in vitro. The arrangement of DNA sequences recognised by the chloroplast RNA polymerase resembles the prokaryotic promoter organization. Images Fig. 3. Fig. 5. Fig. 6. PMID:2992936

Gruissem, W; Zurawski, G

1985-01-01

160

In vitro analysis of riboswitch-spinach aptamer fusions as metabolite-sensing fluorescent biosensors.  

PubMed

The development of fluorescent biosensors has been motivated by the interest to monitor and measure the levels of specific metabolites in live cells in real time. Common approaches include fusing a protein-based receptor to fluorescent proteins or synthesizing a small molecule reactive probe. Natural metabolite-sensing riboswitches also have been used in reporter-based systems that take advantage of ligand-dependent regulation of downstream gene expression. More recently, it has been shown that RNA-based fluorescent biosensors can be generated by fusing a riboswitch aptamer to the in vitro selected Spinach aptamer, which binds a cell-permeable and conditionally fluorescent molecule. Here, we describe methods to design, prepare, and analyze riboswitch-Spinach aptamer fusion RNAs for ligand-dependent activation of fluorescence in vitro. Examples of procedures to measure fluorescence activation, ligand binding selectivity and affinity, and binding kinetics are given for a cyclic di-GMP-responsive biosensor. The relative ease of in vitro RNA synthesis and purification should make this method accessible to other researchers interested in developing riboswitch-based fluorescent biosensors. PMID:25605385

Kellenberger, Colleen A; Hammond, Ming C

2015-01-01

161

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

Houston, Carolyn; Hargis, Jace

2000-05-01

162

Leaf Tissue Senescence  

PubMed Central

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

Manos, Peter J.; Goldthwaite, Jonathan

1975-01-01

163

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; ÜLo Niinemets; Matthew J. Germino

164

Chloroplast to Leaf  

Microsoft Academic Search

\\u000a Leaf shapes and morphologies are very diverse. Obviously there are many successful solutions to the challenge of constructing\\u000a an organ that intercepts light, enables CO2 uptake, restricts water loss, and withstands or avoids temperature extremes, herbivory, and disease. Tradeoffs exist among\\u000a capturing CO2 and light, water loss, or construction cost. So, to some extent, the various leaf structures represent different

John R. Evans; Ichiro Terashima; Yuko Hanba; Francesco Loreto

165

Leaf to Landscape  

Microsoft Academic Search

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

Alessandro Cescatti; Ülo Niinemets

166

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

167

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 ...

168

Nine grain bun with salmon, turkey burger or spicy black bean burger. Add spinach, pickles, tomatoes, red onion, and  

E-print Network

The Grill Nine grain bun with salmon, turkey burger or spicy black bean burger. Add spinach in South America Turkey or Tofu- Both rich with protein Cheddar or Parmesan Cheese- Good source of calcium, salsa roja, salsa verde, pork carnitas, tofu fajitas Thursday LUNCH: Turkey Pot Pie or Vegetable Pot Pie

Carter, John

169

The structure of the gene for the large subunit of ribulose 1,5-bisphosphate carboxylase from spinach chloroplast DNA.  

PubMed Central

A cloned fragment of spinach chloroplast DNA carrying the gene for the large subunit of ribulose bisphosphate (RuBP) carboxylase has been analysed by electron microscopy of R-loops, by hybridization to Northern blots of chloroplast RNA, by S1 nuclease mapping and by DNA sequencing. The transcribed region of the gene is 1690 +/- 3 nucleotides long and co-linear with its mRNA. It comprises a 178-179 bp 5' untranslated sequence, a 1425 bp coding region and an 85-88 bp 3' untranslated region. The deduced sequence of the 475 amino acids of the spinach large subunit protein shows 10% divergence from that of the maize large subunit protein (1). The nucleotide sequence divergence between spinach and maize over the same coding region is 16% but in the transcribed flanking regions it is 35%. Features of the spinach chloroplast gene which resemble those of bacterial genes include a 5-base Shine-Dalgarno sequence complementary to a sequence near the 3' end of chloroplast and bacterial 16S rRNA, a promoter region partially homologous to a consensus sequence of bacterial promoters, and a transcription termination region capable of forming a typical stem and loop structure. Images PMID:6269077

Zurawski, G; Perrot, B; Bottomley, W; Whitfeld, P R

1981-01-01

170

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,...

171

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

PubMed

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

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

2008-08-01

172

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

173

Buffer Capacities of Leaves, Leaf Cells, and Leaf Cell Organelles in Relation to Fluxes of Potentially Acidic Gases 1  

PubMed Central

Since environmental pollution by potentially acidic gases such as SO2 causes proton release inside leaf tissues, homogenates of needles of spruce (Picea abies) and fir (Abies alba) and of leaves of spinach (Spinacia oleracea) and barley (Hordeum vulgare) were titrated and buffer capacities were determined as a function of pH. Titration curves of barley leaves were compared with titration curves of barley mesophyll protoplasts. From the protoplasts, chloroplasts and vacuoles were isolated and subjected to titration experiments. From the titration curves, the intracellular distribution of buffering capacities could be deduced. Buffering was strongly pH-dependent. It was high at the extremes of pH but still significant close to neutrality. Owing to its large size, the vacuole was mainly responsible for cellular buffering. However, on a unit volume basis, the cytoplasm was much more strongly buffered than the vacuole. Potentially acidic gases are trapped in the anionic form. They release protons when trapped. The magnitude of diffusion gradients from the atmosphere into the cells, which determines flux, depends on intracellular pH. In the light, the chloroplast stroma, as the most alkaline leaf compartment, has the highest trapping potential. Acidification of the chloroplast stroma inhibits photosynthesis. The trapping potential of the chloroplast is followed by that of the cytosol. Compared with the cytoplasm, the vacuole possesses little trapping potential in spite of its large size. It is particularly small in the acidic vacuoles of conifer needles. In the physiological pH range (slightly above neutrality), chloroplast buffering was about 1 microequivalents H+ per milligram chlorophyll per pH unit or 35 microequivalents H+ per milliliter per pH unit in barley or spinach chloroplasts. This compares with SO2-generated H+ production of somewhat more than 1 microequivalent H+ per milligram chlorophyll per hour, which results from observed SO2 uptake of leaves when stomata were open and the atmospheric SO2 concentration was 0.4 microliters per liter (GE Taylor Jr, DT Tingey 1983 Plant Physiol 72: 237-244). At lower SO2 concentrations, similar H+ generation inside the cells requires correspondingly longer exposure times. PMID:16664863

Pfanz, Hardy; Heber, Ulrich

1986-01-01

174

Differential Regulation of RNA Levels of Gibberellin Dioxygenases by Photoperiod in Spinach1  

PubMed Central

Previous work with spinach (Spinacia oleracea) has shown that the level of gibberellin (GA) 20-oxidase is strongly up-regulated by long days (LD). In the present work, the effect of photoperiod on expression of other GA dioxygenases was investigated and compared with that of GA 20-oxidase. Two GA 2-oxidases and one GA 3-oxidase were isolated from spinach by reverse transcription-polymerase chain reaction with degenerate primers and by 5?- and 3?-rapid amplification of cDNA ends. As determined by high-performance liquid chromatography with on-line radioactivity detection, the SoGA3ox1 gene product catalyzed 3?-hydroxylation of GA9 to GA4 and GA20 to GA1. The SoGA2ox1 and the SoGA2ox2 gene products catalyzed 2?-hydroxylation of GA9 to GA51 and GA20 to GA29. The product of GA20 metabolism by SoGA3ox1 was identified as GA1 by gas chromatography-mass spectrometry, whereas the products of GA1 and GA20 metabolism by SoGA2ox1 and SoGA2ox2 were identified as GA8 and GA29, respectively. SoGA2ox1 also metabolized GA53 to GA97. The levels of SoGA20ox1 transcripts were greatly increased in all organs tested in LD conditions, but the levels of SoGA3ox1 transcripts were only slightly increased in blades and petioles. A decrease in the levels of the SoGA2ox1 transcripts in young leaves and tips in LD conditions is opposite to the expression pattern of the SoGA20ox1. Expression of SoGA20ox1 in petioles and young leaves was strongly up-regulated by a supplementary 16 h of light, but the levels of SoGA3ox1 and SoGA2ox1 transcripts did not change. It is concluded that regulation and maintenance of GA1 concentration in spinach are primarily attributable to changes in expression of SoGA20ox1. PMID:12481092

Lee, Dong Ju; Zeevaart, Jan A.D.

2002-01-01

175

Microbial quality of bagged baby spinach and romaine lettuce: effects of top versus bottom sampling.  

PubMed

Contamination with Escherichia coli O157:H7 and Salmonella have called into question the safety and microbial quality of bagged ready-to-eat leafy greens. This study expands on previous findings that these goods have high total bacteria counts (TBC) and coliform counts, variation in counts among different lots, that Escherichia coli is present, and disparities in counts when bags are top or bottom sampled. Nearly 100 bags of baby spinach and hearts of romaine lettuce from a single brand were subjected to both top and bottom sampling. Product was blended, and a portion serially diluted and plated to obtain TBC. Total coliform and E. coli levels were estimated by the most-probable-number (MPN) technique with ColiComplete discs. Top-sampled TBC from bags of baby spinach (48 bags, 13 different lots) ranged from 3.9 to 8.1 log CFU/g and bottom-sampled TBC ranged from 4.0 to 8.2 log CFU/g, with 52% of the bags (or 39% of the lots) producing TBC higher in bottom samples. For hearts of romaine (47 bags from 19 different lots), top-sampled bags had TBC ranging from 2.4 to 7.0 log, and bottom-sampled bags had TBC from 3.3 to 7.3 log, with 64% of the bags (or 63% of the lots) showing higher TBC in bottom samples. However, we are unable to reject the hypothesis that the top and bottom samples from either commodity contain the same TBC (P ? 0.08). No E. coli was detected and total coliform bacteria counts were, with few exceptions, ?210 MPN/g, irrespective of TBC. In general, lots with the most number of days before the printed "use-by" date had lower TBC. However, the R(2) values for either baby spinach (0.4085) or hearts of romaine (0.2946) suggest that age might not be a very good predictor of higher TBC. TBC varied widely between lots and even more so within same-lot samples, as indicated by the sum of squares results. This finding, along with higher TBC in bottom samples, suggests further consideration when a microbiological sampling scheme of bagged produce is designed. PMID:22221365

Kase, Julie A; Borenstein, Stacey; Blodgett, Robert J; Feng, Peter C H

2012-01-01

176

Photosynthetic Intermediates, The Warburg Effect, and Glycolate Synthesis in Isolated Spinach Chloroplasts 1  

PubMed Central

Increasing levels of CO2 have been shown to stimulate the rate of photosynthesis, eliminate the oxygen inhibition of photosynthesis (Warburg effect), and decrease glycolate formation in isolated spinach chloroplasts. Ribose 5-phosphate and fructose 1,6-diphosphate at concentrations of 5 to 10 ?m also stimulate the rate of plastid photosynthesis and eliminate the Warburg effect. In contrast to the effect of high CO2 levels, these sugar phosphates have little effect on glycolate formation. Evidence is presented to show that the level of intermediates of the photosynthetic carbon reduction cycle may influence the Warburg effect in vivo. It is postulated that the formation of glycolate is not the causal factor of the Warburg effect. PMID:16658792

Robinson, J. Michael; Gibbs, Martin

1974-01-01

177

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

PubMed

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

Coughlan, S J; Heber, U

1982-11-01

178

The spinach RNA aptamer as a characterization tool for synthetic biology.  

PubMed

Characterization of genetic control elements is essential for the predictable engineering of synthetic biology systems. The current standard for in vivo characterization of control elements is through the use of fluorescent reporter proteins such as green fluorescent protein (GFP). Gene expression, however, involves not only protein production but also the production of mRNA. Here, we present the use of the Spinach aptamer sequence, an RNA mimic of GFP, as a tool to characterize mRNA expression in Escherichia coli. We show how the aptamer can be incorporated into gene expression cassettes and how co-expressing it with a red fluorescent protein (mRFP1) allows, for the first time, simultaneous measurement of mRNA and protein levels from engineered constructs. Using flow cytometry, we apply this tool here to evaluate ribosome binding site sequences and promoters and use it to highlight the differences in the temporal behavior of transcription and translation. PMID:23991760

Pothoulakis, Georgios; Ceroni, Francesca; Reeve, Benjamin; Ellis, Tom

2014-03-21

179

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

180

LEAF-E: a tool to analyze grass leaf growth using function fitting.  

PubMed

In grasses, leaf growth is often monitored to gain insights in growth processes, biomass accumulation, regrowth after cutting, etc. To study the growth dynamics of the grass leaf, its length is measured at regular time intervals to derive the leaf elongation rate (LER) profile over time. From the LER profile, parameters such as maximal LER and leaf elongation duration (LED), which are essential for detecting inter-genotype growth differences and/or quantifying plant growth responses to changing environmental conditions, can be determined. As growth is influenced by the circadian clock and, especially in grasses, changes in environmental conditions such as temperature and evaporative demand, the LER profiles show considerable experimental variation and thus often do not follow a smooth curve. Hence it is difficult to quantify the duration and timing of growth. For these reasons, the measured data points should be fitted using a suitable mathematical function, such as the beta sigmoid function for leaf elongation. In the context of high-throughput phenotyping, we implemented the fitting of leaf growth measurements into a user-friendly Microsoft Excel-based macro, a tool called LEAF-E. LEAF-E allows to perform non-linear regression modeling of leaf length measurements suitable for robust and automated extraction of leaf growth parameters such as LER and LED from large datasets. LEAF-E is particularly useful to quantify the timing of leaf growth, which forms an important added value for detecting differences in leaf growth development. We illustrate the broad application range of LEAF-E using published and unpublished data sets of maize, Miscanthus spp. and Brachypodium distachyon, generated in independent experiments and for different purposes. In addition, we show that LEAF-E could also be used to fit datasets of other growth-related processes that follow the sigmoidal profile, such as cell length measurements along the leaf axis. Given its user-friendliness, ability to quantify duration and timing of leaf growth and broad application range, LEAF-E is a tool that could be routinely used to study growth processes following the sigmoidal profile. PMID:25435898

Voorend, Wannes; Lootens, Peter; Nelissen, Hilde; Roldán-Ruiz, Isabel; Inzé, Dirk; Muylle, Hilde

2014-01-01

181

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.

182

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

PubMed

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

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

2014-05-01

183

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...

184

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.

185

Spinach plastid genes coding for initiation factor IF-1, ribosomal protein S11 and RNA polymerase alpha-subunit.  

PubMed Central

The nucleotide sequence of 2.5 kbp from the cloned SalI fragments 8 and 11 of spinach plastid DNA has been determined. This region was found to encode three open reading frames for hydrophilic polypeptides of 77, 138, and 335 amino acids. Using the computer search algorithm of Lipman and Pearson (Science 227, 1435, 1985), these genes were identified as coding for homologues of E. coli initiation factor IF-1 (inFA), 30S ribosomal protein S11 (rps11), and the alpha-subunit of DNA-dependent RNA polymerase (rpoA). The spinach plastid gene organization is inFA - 381 bp spacer - rps11 - 72 bp spacer - rpoA. The genes are transcribed in vivo and appear to encode functional proteins. These findings imply that plastid chromosomes code for components of the organelle transcription apparatus. Images PMID:3003688

Sijben-Müller, G; Hallick, R B; Alt, J; Westhoff, P; Herrmann, R G

1986-01-01

186

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

E-print Network

LEAF GUI: User Manual (Leaf Extraction and Analysis Framework Graphical User Interface) #12;LEAF GUI User Manual Price et al. Index How to cite the LEAF GUI......................................................................................................................Page 28 2 #12;LEAF GUI User Manual Price et al. How to cite the LEAF GUI The LEAF GUI

Weitz, Joshua S.

187

Total and individual carotenoids and phenolic acids content in fresh, refrigerated and processed spinach ( Spinacia oleracea L.)  

Microsoft Academic Search

The carotenoid and phenolic acid contents in fresh, stored and processed (blanched, frozen and boiled) spinach were comparatively determined by spectrophotometric and HPLC analyses. The major carotenoids identified after HPLC analysis in saponified samples were lutein (37–53?g\\/kg), ?-carotene (18–31?g\\/kg), violaxanthin (9–23?g\\/kg) and neoxanthin (10–22?g\\/kg). These carotenoids were all affected by storage and\\/or heating. The content of carotenoids was best preserved

Andrea Bunea; Mirjana Andjelkovic; Carmen Socaciu; Otilia Bobis; Madalina Neacsu; Roland Verhé; John Van Camp

2008-01-01

188

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

PubMed Central

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 15 mM). 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 3 mM 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; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel; Aarab, Ahmed; Lafont, René

2012-01-01

189

The Effects of lllumination on the Xanthophyll Composition of the Photosystem II Light-Harvesting Complexes of Spinach Thylakoid Membranes  

Microsoft Academic Search

~~ lhe xanthophyll composition of the light-harvesting chlorophyll a\\/b proteins of photosystem II (LHCII) has been determined for spinach (Spinacia oleracea 1.) leaves after dark adaptation and following illumination under conditions optimized for conversion of violaxanthin into zeaxanthin. Each of the four LHCll components was found to have a unique xanthophyll composition. lhe major carotenoid was lutein, comprising 60% of

Alexander V. Ruban; Andrew J. Young; Andrew A. Pascal; Peter Horton

1994-01-01

190

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

PubMed

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 water with and without ultrasound (21.2 kHz) for 2 min at room temperature. The effects of ultrasound treatment time and acoustic energy density (AED) were evaluated at an ASC concentration of 200 mg/L. The effect of ASC concentration, with a fixed AED of 200 W/L, was also examined. Microbial analysis indicated that ASC reduced E. coli O157 : H7 population by 2.2 log cycles over that of water wash, while the reduction from other sanitizers was about 1 log cycle. Ultrasonication significantly enhanced the reduction of E. coli cells on spinach for all treatments by 0.7 to 1.1 log cycle over that of washes with sanitizer alone. An increase in the ASC concentration enhanced the efficacy of the combined treatment of ASC and ultrasonication, especially at ASC concentrations of < 300 mg/L. Increasing the ultrasound treatment time from 0 to 4 min and AED from 0 to 500 W/L were both effective in increasing the effectiveness of the ASC and ultrasound combined treatments. In addition, E. coli O157 : H7 inoculated on the underside of spinach leaves (rough side) were more difficult to remove than those inoculated on the upper side (smooth side). PMID:19723216

Zhou, Bin; Feng, Hao; Luo, Yaguang

2009-08-01

191

Molecular Cloning of GA 2-Oxidase3 from Spinach and Its Ectopic Expression in Nicotiana sylvestris1  

PubMed Central

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.

2005-01-01

192

Characterization of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase activase isoforms reveals hexameric assemblies with increased thermal stability.  

PubMed

Most plants contain two isoforms of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (Rca), a chloroplast protein that maintains the activity of Rubisco during photosynthesis. The longer (?-) Rca isoform has previously been shown to regulate the activity of Rubisco in response to both the ADP:ATP ratio and redox potential via thioredoxin-f. We have characterized the arrangement of the different spinach (Spinacia oleracea) isoforms in solution, and show how the presence of nucleotides changes the oligomeric state. Although the shorter (?-) isoform from both tobacco (Nicotiana tabacum) and spinach tend to form a range of oligomers in solution, the size of which are relatively unaffected by the addition of nucleotide, the spinach ?-isoform assembles as a hexamer in the presence of adenosine 5'-[?-thio]triphosphate (ATP?S). These hexamers have significantly higher heat stability, and may play a role in optimizing photosynthesis at higher temperatures. Hexamers were also observed for mixtures of the two isoforms, suggesting that the ?-isoform can act as a structural scaffold for hexamer formation by the ?-isoform. Additionally, it is shown that a variant of the tobacco ?-isoform acts in a similar fashion to the ?-isoform of spinach, forming thermally stable hexamers in the presence of ATP?S. Both isoforms had similar rates of ATP hydrolysis, suggesting that a propensity for hexamer formation may not necessarily be correlated with activity. Modelling of the hexameric structures suggests that although the N-terminus of Rca forms a highly dynamic, extended structure, the C-terminus is located adjacent to the intersubunit interface. PMID:25247706

Keown, Jeremy R; Pearce, Frederick Grant

2014-12-15

193

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

MacLeod, John K.

2006-01-01

194

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

195

Methods for Observing Microbial Biofilms Directly on Leaf Surfaces and Recovering Them for Isolation of Culturable Microorganisms  

PubMed Central

Epifluorescence microscopy, scanning electron microscopy, and confocal laser scanning microscopy were used to observe microbial biofilms directly on leaf surfaces. Biofilms were observed on leaves of all species sampled (spinach, lettuce, Chinese cabbage, celery, leeks, basil, parsley, and broad-leaved endive), although the epifluorescent images were clearest when pale green tissue or cuticle pieces were used. With these techniques, biofilms were observed that were about 20 (mu)m in depth and up to 1 mm in length and that contained copious exopolymeric matrices, diverse morphotypes of microorganisms, and debris. The epifluorescence techniques described here can be used to rapidly determine the abundance and localization of biofilms on leaves. An additional technique was developed to recover individual biofilms or portions of single biofilms from leaves and to disintegrate them for isolation of the culturable microorganisms they contained. Nineteen biofilms from broad-leaved endive, spinach, parsley, and olive leaves were thus isolated and characterized to illustrate the applications of this technique. PMID:16535579

Morris, C. E.; Monier, J.; Jacques, M.

1997-01-01

196

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

PubMed Central

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

Fu, Chee Fook; Gibbs, Martin

1988-01-01

197

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

SciTech Connect

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

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

1981-05-01

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 50°C), 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 40°C, and ultrasonic power of 50%. The mean yield (mg/100g), total phenol (mg gallic acid/g DW), flavonoids (mg/g DW), % DPPH free-radical scavenging activity, and % ferric reducing antioxidant power were all high (64.88±21.84, 33.96±11.30, 27.37±11.85, 64.18±16.69 and 70.25±9.68). Treatments were significantly different. The interaction among the ultrasonic parameters was significant. Temperature and power had significant effects on all other dependent variables. PMID:25465093

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

2015-05-01

199

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

PubMed

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

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

2014-09-10

200

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

201

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

SciTech Connect

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

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

1987-09-01

202

Localization of ATP Sulfurylase and O-Acetylserine(thiol)lyase in Spinach Leaves  

PubMed Central

The intracellular compartmentation of ATP sulfurylase and O-acetylserine(thiol)lyase in spinach (Spinacia oleracea L.) leaves has been investigated by isolation of organelles and fractionation of protoplasts. ATP sulfurylase is located predominantly in the chloroplasts, but is also present in the cytosol. No evidence was found for ATP sulfurylase activity in the mitochondria. Two forms of ATP sulfurylase were separated by anion-exchange chromatography. The more abundant form is present in the chloroplasts, the second is cytosolic. O-Acetylserine(thiol)lyase activity is located primarily in the chloroplasts and cytosol, but is also present in the mitochondria. Three forms of O-acetylserine(thiol)lyase were separated by anion-exchange chromatography, and each was found to be specific to one intracellular compartment. The cytosolic ATP sulfurylase may not be active in vivo due to the unfavorable equilibrium constant of the reaction, and the presence of micromolar concentrations of inorganic pyrophosphate in the cytosol, therefore its role remains unknown. It is suggested that the plant cell may be unable to transport cysteine between the different compartments, so that the cysteine required for protein synthesis must be synthesized in situ, hence the presence of O-acetylserine(thiol)lyase in the three compartments where proteins are synthesized. PMID:16667839

Lunn, John E.; Droux, Michel; Martin, Jacqueline; Douce, Roland

1990-01-01

203

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 Å, and ?=104.34° and diffracted to 4.5 Å resolution. Each c-ring contains 14 monomers in the asymmetric unit. The length of the c-ring is 60.32 Å, with an outer ring diameter 52.30 Å and an inner ring width of 40 Å. PMID:24521269

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

2014-01-01

204

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

PubMed

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

2014-07-01

205

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

206

Radiative characteristics of plant leaf  

Microsoft Academic Search

Existing leaf radiation models are reviewed. A new concept of the optical model of the leaf as a multiphase system containing\\u000a three aggregate ensembles of particles significantly different in microphysical and optical characteristics is proposed. The\\u000a proposed model is based on the reconstruction of the particle size distribution function from the experimental leaf absorption\\u000a spectrum. Based on the obtained microphysical

G. M. Krekov; M. M. Krekova; A. A. Lisenko; A. Ya. Sukhanov

2009-01-01

207

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

E-print Network

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

Verroust-Blondet, Anne

208

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 as seasonal change in leaf area resulting from net leaf flushing in the dry season or net leaf abscission and as change in leaf scattering and absorption properties between younger and older leaves covered

Goldberg, Bennett

209

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

210

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

...2 2011-01-01 2011-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture ...INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its...

2011-01-01

211

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...2 2010-01-01 2010-01-01 false Leaf structure. 29.6023 Section 29.6023 Agriculture ...INSPECTION Standards Definitions § 29.6023 Leaf structure. The cell development of a leaf as indicated by its...

2010-01-01

212

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

213

7 CFR 29.6022 - Leaf scrap.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

214

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

215

7 CFR 29.6022 - Leaf scrap.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

216

7 CFR 29.2529 - Leaf scrap.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf scrap. 29.2529 Section 29.2529 Agriculture...23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

2010-01-01

217

7 CFR 29.6022 - Leaf scrap.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

218

7 CFR 29.6022 - Leaf scrap.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture...INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

2010-01-01

219

7 CFR 29.2529 - Leaf scrap.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

220

7 CFR 29.6023 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

221

7 CFR 29.2529 - Leaf scrap.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

222

7 CFR 29.2529 - Leaf scrap.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

223

7 CFR 29.6022 - Leaf scrap.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf scrap. 29.6022 Section 29.6022 Agriculture...INSPECTION Standards Definitions § 29.6022 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

2011-01-01

224

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

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

2014-05-13

225

Photosynthetic and Carbohydrate Metabolism in Isolated Leaf Cells of Digitaria pentzii 12  

PubMed Central

Mesophyll cells and bundle sheath strands were isolated rapidly from leaves of the C4 species Digitaria pentzii Stent. (slenderstem digitgrass) by a chopping and differential filtration technique. Rates of CO2 fixation in the light by mesophyll and bundle sheath cells without added exogenous substrates were 6.3 and 54.2 micromoles of CO2 per milligram of chlorophyll per hour, respectively. The addition of pyruvate or phosphoenolpyruvate to the mesophyll cells increased the rates to 15.2 and 824.6 micromoles of CO2 per milligram of chlorophyll per hour, respectively. The addition of ribose 5-phosphate increased the rate for bundle sheath cells to 106.8 micromoles of CO2 per milligram of chlorophyll per hour. These rates are comparable to those reported for cells isolated by other methods. The Km(HCO3?) for mesophyll cells was 0.9 mm; for bundle sheath cells it was 1.3 mm at low, and 40 mm at higher HCO3? concentrations. After 2 hours of photosynthesis by mesophyll cells in 14CO2 and phosphoenolpyruvate, 88% of the incorporated 14C was found in organic acids and 0.8% in carbohydrates; for bundle sheath cells incubated in ribose 5-phosphate and ATP, more than 58% of incorporated 14C was found in carbohydrates, mainly starch, and 32% in organic acids. These findings, together with the stimulation of CO2 fixation by phosphoenolpyruvate for mesophyll cells and by ribose 5-phosphate plus ATP for bundle sheath cells, and the location of phosphoenolpyruvate and ribulose bisphosphate carboxylases in mesophyll and bundle sheath cells, respectively, are in accord with the scheme of C4 photosynthesis which places the Calvin cycle in the bundle sheath and C4 acid formation in mesophyll cells. Starch and reducing sugars were present in both mesophyll and bundle sheath cells following a period of photosynthesis by whole leaves. However, when isolated cells were exposed to 14CO2 in the light, even with appropriate exogenous substrates, only bundle sheath cells accumulated appreciable amounts of labeled carbohydrates. Incubation of mesophyll cells in the light with ATP and either pyruvate and inorganic phosphate, or phosphoenolpyruvate, or 3-phosphoglycerate resulted in large increases in total carbohydrates. The 3-phosphoglycerate treatment produced the greatest increase. These results could not be explained on the basis of increased CO2 fixation. They suggest that mesophyll cells are able to metabolize exogenously supplied 3-carbon compounds to carbohydrates, despite the apparent inability of these cells to utilize CO2 for this purpose, and support the view that in the whole leaf 3-phosphoglycerate is transported from bundle sheath to mesophyll cells, where it is reduced to carbohydrate. Sucrose and sucrose-phosphate synthetases and invertase were localized mainly in bundle sheath cells. ADP-Glucose starch synthetase and amylase were present mainly in bundle sheath cells whereas starch phosphorylase was present mainly in mesophyll cells. PMID:16660549

Mbaku, Sala B.; Fritz, George J.; Bowes, George

1978-01-01

226

The artificial leaf.  

PubMed

To convert the energy of sunlight into chemical energy, the leaf splits water via the photosynthetic process to produce molecular oxygen and hydrogen, which is in a form of separated protons and electrons. The primary steps of natural photosynthesis involve the absorption of sunlight and its conversion into spatially separated electron-hole pairs. The holes of this wireless current are captured by the oxygen evolving complex (OEC) of photosystem II (PSII) to oxidize water to oxygen. The electrons and protons produced as a byproduct of the OEC reaction are captured by ferrodoxin of photosystem I. With the aid of ferrodoxin-NADP(+) reductase, they are used to produce hydrogen in the form of NADPH. For a synthetic material to realize the solar energy conversion function of the leaf, the light-absorbing material must capture a solar photon to generate a wireless current that is harnessed by catalysts, which drive the four electron/hole fuel-forming water-splitting reaction under benign conditions and under 1 sun (100 mW/cm(2)) illumination. This Account describes the construction of an artificial leaf comprising earth-abundant elements by interfacing a triple junction, amorphous silicon photovoltaic with hydrogen- and oxygen-evolving catalysts made from a ternary alloy (NiMoZn) and a cobalt-phosphate cluster (Co-OEC), respectively. The latter captures the structural and functional attributes of the PSII-OEC. Similar to the PSII-OEC, the Co-OEC self-assembles upon oxidation of an earth-abundant metal ion from 2+ to 3+, may operate in natural water at room temperature, and is self-healing. The Co-OEC also activates H(2)O by a proton-coupled electron transfer mechanism in which the Co-OEC is increased by four hole equivalents akin to the S-state pumping of the Kok cycle of PSII. X-ray absorption spectroscopy studies have established that the Co-OEC is a structural relative of Mn(3)CaO(4)-Mn cubane of the PSII-OEC, where Co replaces Mn and the cubane is extended in a corner-sharing, head-to-tail dimer. The ability to perform the oxygen-evolving reaction in water at neutral or near-neutral conditions has several consequences for the construction of the artificial leaf. The NiMoZn alloy may be used in place of Pt to generate hydrogen. To stabilize silicon in water, its surface is coated with a conducting metal oxide onto which the Co-OEC may be deposited. The net result is that immersing a triple-junction Si wafer coated with NiMoZn and Co-OEC in water and holding it up to sunlight can effect direct solar energy conversion via water splitting. By constructing a simple, stand-alone device composed of earth-abundant materials, the artificial leaf provides a means for an inexpensive and highly distributed solar-to-fuels system that employs low-cost systems engineering and manufacturing. Through this type of system, solar energy can become a viable energy supply to those in the non-legacy world. PMID:22475039

Nocera, Daniel G

2012-05-15

227

The worldwide leaf economics spectrum  

Microsoft Academic Search

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

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

2004-01-01

228

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...

229

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

PubMed

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

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

2012-05-15

230

Effect of Osmotic Stress on Photosynthesis Studied with the Isolated Spinach Chloroplast 1  

PubMed Central

The effects of reduced osmotic potential on the photosynthetic carbon reduction cycle were investigated by monitoring photosynthetic processes of spinach (Spinacia oleracea L. var. Long Standing Bloomsdale) chloroplasts exposed to increased assay medium sorbitol concentrations. CO2 assimilation was found to be inhibited at 0.67 molar sorbitol by about 60% from control rates at 0.33 molar sorbitol. This level of stress inhibition was greater than that affecting the reductive phase of the cycle; glycerate 3-phosphate reduction was inhibited at 0.67 molar by 27 to 40%. Sorbitol (0.67 molar) inhibited the rate of O2 evolution at saturating and limiting concentrations of NaHCO3, and extended the lag phase of O2 evolution. This indicated that factors which are rate-limiting to the photosynthetic process are adversely affected by reduced osmotic potential. Analysis of photosynthetic products following CO2 fixation in 0.33 molar sorbitol and 0.67 molar sorbitol indicated that reduced osmotic potential facilitated increases in the levels of fructose 1,6-bisphosphate and triose phosphates with reductions in glucose 6-phosphate and fructose 6-phosphate, implicating fructose 1,6-bisphosphatase as a site of osmotic stress. Osmotic inhibition of the reductive portion (glycerate 3-phosphate to triose phosphate) of the photosynthetic carbon reduction cycle was partially attributed to feedback inhibition by the product, triose phosphate, on glycerate 3-phosphate reduction. A saturating concentration of ribose 5-phosphate partially overcame osmotic inhibition of CO2-supported O2 evolution, indicating another but apparently less severe site of stress inhibition in the sequence of ribose 5-phosphate to glycerate 3-phosphate. PMID:16662712

Berkowitz, Gerald A.; Gibbs, Martin

1982-01-01

231

Incision at nucleotide insertions/deletions and base pair mismatches by the SP nuclease of spinach.  

PubMed

Spinach leaves contain a highly active nuclease called SP. The purified enzyme incises single-stranded DNA, RNA, and double-stranded DNA that has been destabilized by A-T-rich regions and DNA lesions [Strickland et al. (1991) Biochemistry 30, 9749-9756]. This broad range of activity has suggested that SP may be similar to a family of nucleases represented by S1, P1, and the mung bean nuclease. However, unlike these single-stranded nucleases that require acidic pH and low ionic strength conditions, SP has a neutral pH optimum and is active over a wide range of salt concentrations. We have extended these findings and showed that an outstanding substrate for SP is a mismatched DNA duplex. For base-substitution mismatches, SP incises at all mismatches except those containing a guanine residue. SP also cuts at insertion/deletions of one or more nucleotides. Where the extrahelical DNA loop contains one nucleotide, the preference of extrahelical nucleotide is A > T approximately C but undetectable at G. The inability of SP to cut at guanine residues and the favoring of A-T-rich regions distinguish SP from the CEL I family of neutral pH mismatch endonucleases recently discovered in celery and other plants [Oleykowski et al. (1998) Nucleic Acids Res. 26, 4597-4602]. SP, like CEL I, does not turn over after incision at a mismatched site in vitro. Similar to CEL I, the presence of a DNA polymerase or a DNA ligase allows SP to turn over and stimulate its activity in vitro by about 20-fold. The possibility that the SP nuclease may be a natural variant of the CEL I family of mismatch endonucleases is discussed. PMID:10026304

Oleykowski, C A; Bronson Mullins, C R; Chang, D W; Yeung, A T

1999-02-16

232

Visualization of a Spinach Plastid Transcriptionally Active DNA-Protein Complex in a Highly Condensed Structure  

PubMed Central

A transcriptionally active DNA-protein complex isolated from spinach Spinacia oleracea plastids is visualized by electron microscopy in different conditions. This structure, after glutaraldehyde fixation, is highly condensed. DNA is supertwisted with proteins bound to it producing a beaded substructure. When glutaraldehyde fixation is omitted this structure is less condensed and DNA fibrils come out from a proteinous central body. The DNA-protein complex can be separated into two populations by CsCl centrifugation: one with a buoyant density of 1.570 grams per cubic centimeter and the other of 1.610 grams per cubic centimeter. By visualization of these two populations, it is concluded that proteins are either firmly bound to DNA in the central body, or more loosely bound to the DNA fibrils. These latter proteins could play a role in enzymic functions and/or in the supercoiling of DNA. The DNA from the DNA-protein complex possesses all fragments that belong to pure circular chloroplast DNA hydrolyzed by two restriction enzymes: Bam HI and Eco RI. Some molecules observed in a supercondensed form with a beaded substructure probably contain entire chloroplast DNA molecules. A hydrolysis test with microccocal nuclease gives no indication of the presence of `nucleosome-like' structures. Thirty-six polypeptides with molecular weights ranging from 12,000 to 180,000 are present in the complex, and seven of them are highly soluble in 0.4 n H2SO4; their molecular weights range from 14,000 to 46,000 as shown by two-dimensional gel electrophoresis. No linolenic acid can be detected in the preparation, indicating the absence of chloroplast membranes. Images PMID:16662371

Briat, Jean F.; Gigot, Claude; Laulhere, Jean P.; Mache, Regis

1982-01-01

233

Prevalence of multiple antibiotic-resistant Gram-negative bacteria on bagged, ready-to-eat baby spinach  

Microsoft Academic Search

In this study, multiple antibiotic-resistant (MAR) Gram-negative bacteria (GNB) were isolated from triple-washed, bagged, ready-to-eat (RTE) baby spinach. Biochemical identification of randomly selected bacterial colonies showed the predominance of cytochrome oxidase-positive Pseudomonas species. Among the GNB, a higher prevalence of resistance was observed against cefoxitin (93.1%) followed by ampicillin (79.4%), chloramphenicol (72.6%), ceftizoxime (65.7%), aztreonam (64.9%), cefotaxime (53.6%), imipenem (38.3%),

Sandeep Walia; Sonia W. Rana; Daniel Maue; Jatin Rana; Ashok Kumar; Satish K. Walia

2012-01-01

234

Kinetic studies on the hydroxylation of p-coumaric acid to caffeic acid by spinach-beet phenolase.  

PubMed Central

1. A spectrophotometric assay is described that enables the hydroxylation of p-coumaric acid to caffeic acid, catalysed by spinach-beet phenolase, to be followed continuously. 2. Initial-velocity and inhibitor studies indicate that the order of substrate addition is oxygen, p-coumaric acid and electron donor, with an irreversible step separating the binding of each substrate. 3. Caffeic acid is most likely to act as electron donor at the active site; other electron donors, such as ascorbic acid, NADH and dimethyltetrahydropteridine, function mainly to recycle cofactor amounts of caffeic acid. 4. A reaction scheme, consistent with these data, is proposed. PMID:170916

McIntyre, R J; Vaughan, P F

1975-01-01

235

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 (280-315 nm; 7.2 kJ m(-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

236

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

237

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

238

Glu 103 Gln site-directed mutation causes an alteration in physical properties of spinach betaine aldehyde dehydrogenase.  

PubMed

Site-directed mutant of spinach betaine aldehyde dehydrogenase (BADH) was obtained by replacing Glu 103 with Gln 103 and the resulting E 103 Q mutant was expressed in Escherichia coli. The mutant BADH as compared to the wild-type BADH was slightly more sensitive to inhibition by NaCl but less sensitive to inhibition by (NH(4))(2)SO(4). Glycinebetaine (GB) activated the wild-type enzyme but not the mutant enzyme. Stronger inhibition by choline was observed in the mutant enzyme than in the wild-type enzyme whereas the reverse was observed for the inhibition by isovaleraldehyde. The mutant enzyme exhibited a broader temperature optimum than the wild-type enzyme, however, the mutant enzyme appeared to be more heat labile. Both mutant and wild-type enzymes could be protected by NAD(+) against thermal inactivation in a similar manner. However, neither GB nor NaCl could afford protection against thermal inactivation in the mutant enzyme whereas some protection was observed in the wild-type enzyme. Similar pH activity profile was obtained for both mutant and wild-type enzymes. The mutant enzyme was less stable than the wild-type enzyme under the pH range of 5-11. Overall results suggest that the negative charge of Glu 103 at the surface of the spinach BADH plays some roles in the maintenance of the structural integrity of the enzyme. PMID:12186739

Incharoensakdi, Aran; Hibino, Takashi; Takabe, Teruhiro

2002-08-01

239

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

240

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

241

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

PubMed

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

Hu, Xiaoqin; You, Huiyan

2009-11-01

242

Leaf death and decomposition during pasture regrowth  

Microsoft Academic Search

Data are presented that describe the pattern of leaf death per ramet and per unit area. Leaf death per ramet was influenced by the number of leaves that died and the weight of the dead leaves. Leaf weight was important in determining differences in seasonal and species death rate per ramet.Leaf death rates reached a maximum of 56 lb D.M.

W. F. Hunt

1971-01-01

243

7 CFR 29.3036 - Leaf surface.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

244

7 CFR 29.2528 - Leaf.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

245

7 CFR 29.3525 - Leaf.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

246

7 CFR 29.3033 - Leaf.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

247

7 CFR 29.3525 - Leaf.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

248

7 CFR 29.1028 - Leaf.  

Code of Federal Regulations, 2011 CFR

...Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture...12, 13, 14 and Foreign Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

2011-01-01

249

7 CFR 29.3033 - Leaf.  

Code of Federal Regulations, 2010 CFR

...Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture...s. Type 31 and Foreign Type 93) § 29.3033 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

2010-01-01

250

7 CFR 29.3036 - Leaf surface.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Leaf surface. 29.3036 Section 29...and Foreign Type 93) § 29.3036 Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

2010-01-01

251

7 CFR 29.1028 - Leaf.  

Code of Federal Regulations, 2010 CFR

...Agriculture 2 2010-01-01 2010-01-01 false Leaf. 29.1028 Section 29.1028 Agriculture...12, 13, 14 and Foreign Type 92) § 29.1028 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

2010-01-01

252

7 CFR 29.3525 - Leaf.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

253

7 CFR 29.2528 - Leaf.  

Code of Federal Regulations, 2011 CFR

...Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.2528 Section 29.2528 Agriculture...Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

2011-01-01

254

7 CFR 29.3033 - Leaf.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

255

7 CFR 29.2528 - Leaf.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

256

7 CFR 29.3036 - Leaf surface.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

257

7 CFR 29.1028 - Leaf.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

258

7 CFR 29.3036 - Leaf surface.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Leaf surface. 29.3036 Section 29...and Foreign Type 93) § 29.3036 Leaf surface. The smoothness or roughness of the web or lamina of a tobacco leaf. Leaf surface is affected to...

2011-01-01

259

7 CFR 29.1028 - Leaf.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

260

7 CFR 29.1028 - Leaf.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

261

7 CFR 29.3525 - Leaf.  

Code of Federal Regulations, 2011 CFR

...Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.3525 Section 29.3525 Agriculture...35, 36, 37 and Foreign Type 95) § 29.3525 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

2011-01-01

262

7 CFR 29.2528 - Leaf.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

263

7 CFR 29.3036 - Leaf surface.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

264

7 CFR 29.3033 - Leaf.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

265

7 CFR 29.3033 - Leaf.  

Code of Federal Regulations, 2011 CFR

...Agriculture 2 2011-01-01 2011-01-01 false Leaf. 29.3033 Section 29.3033 Agriculture...s. Type 31 and Foreign Type 93) § 29.3033 Leaf. Whole, unstemmed leaf. Leaf, when applied to tobacco in strip...

2011-01-01

266

Very Sparse Leaf Languages Lance Fortnow  

E-print Network

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

Fortnow, Lance

267

Very Sparse Leaf Languages # Lance Fortnow +  

E-print Network

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

Fortnow, Lance

268

Protein film voltammetry and co-factor electron transfer dynamics in spinach photosystem II core complex.  

PubMed

Direct protein film voltammetry (PFV) was used to investigate the redox properties of the photosystem II (PSII) core complex from spinach. The complex was isolated using an improved protocol not used previously for PFV. The PSII core complex had high oxygen-evolving capacity and was incorporated into thin lipid and polyion films. Three well-defined reversible pairs of reduction and oxidation voltammetry peaks were observed at 4 °C in the dark. Results were similar in both types of films, indicating that the environment of the PSII-bound cofactors was not influenced by film type. Based on comparison with various control samples including Mn-depleted PSII, peaks were assigned to chlorophyll a (Chl a) (Em = -0.47 V, all vs. NHE, at pH 6), quinones (-0.12 V), and the manganese (Mn) cluster (Em = 0.18 V). PFV of purified iron heme protein cytochrome b-559 (Cyt b-559), a component of PSII, gave a partly reversible peak pair at 0.004 V that did not have a potential similar to any peaks observed from the intact PSII core complex. The closest peak in PSII to 0.004 V is the 0.18 V peak that was found to be associated with a two-electron process, and thus is inconsistent with iron heme protein voltammetry. The -0.47 V peak had a peak potential and peak potential-pH dependence similar to that found for purified Chl a incorporated into DMPC films. The midpoint potentials reported here may differ to various extents from previously reported redox titration data due to the influence of electrode double-layer effects. Heterogeneous electron transfer (hET) rate constants were estimated by theoretical fitting and digital simulations for the -0.47 and 0.18 V peaks. Data for the Chl a peaks were best fit to a one-electron model, while the peak assigned to the Mn cluster was best fit by a two-electron/one-proton model. PMID:23625504

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

2014-05-01

269

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

270

Hormonal Regulation of Leaf Abscission  

PubMed Central

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

Jacobs, William P.

1968-01-01

271

Influence of the interaction between light intensity and CO2 concentration on productivity and quality of spinach (Spinacia oleracea L.) grown in fully controlled environment  

NASA Astrophysics Data System (ADS)

The effects of the factorial combination of two light intensities (200 and 800 ?mol m-2 s-1) and two CO2 concentrations (360 and 800 ppm) were studied on the productivity and nutritional quality of spinach (Spinacia oleracea L.) grown under controlled environment. After 6 weeks within a growth chamber, spinach plants were sampled and analyzed for productivity and quality. There were no statistically significant interactions between the effects of light and CO2 for all of the variables studied, except for the nitrate and oxalic acid content of the leaves. High light and high CO2 independently one from the other, promoted spinach productivity, and the accumulation of ascorbic acid, while their interactive effect limited the accumulation of nitrate and oxalic acid in the spinach leaves. The results highlight the importance of considering the effects of the interaction among environmental variables on maximizing production and the nutritional quality of the food when cultivating and modeling the plant response in controlled environment systems such as for bioregenerative life support.

Proietti, Simona; Moscatello, Stefano; Giacomelli, Gene A.; Battistelli, Alberto

2013-09-01

272

Mathematical modeling and numerical analysis of the growth of Non-O157 shiga toxin-producing Escherichia coli in spinach leaves  

Technology Transfer Automated Retrieval System (TEKTRAN)

This study was conducted to investigate the growth of non-O157 Shiga toxin-producing Escherichia coli (STEC) in spinach leaves and to develop kinetic models to describe the bacterial growth. Six serogroups of non-O157 STEC, including O26, O45, O103, O111, O121, and O145, were used in the growth stu...

273

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

SciTech Connect

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

Liu Chao [College of Life Sciences, Soochow University, Suzhou 215123 (China); Hong Fashui [College of Life Sciences, Soochow University, Suzhou 215123 (China)]. E-mail: Hongfsh_cn@sina.com; Wu Kang [College of Life Sciences, Soochow University, Suzhou 215123 (China); Ma, Hong-bing [College of Life Sciences, Soochow University, Suzhou 215123 (China); Zhang Xueguang [College of Life Sciences, Soochow University, Suzhou 215123 (China); Hong Chengjiao [College of Radiation and Public Sanitation, Soochow University, Suzhou 215123 (China); Wu Cheng [College of Life Sciences, Soochow University, Suzhou 215123 (China); Gao Fengqing [College of Life Sciences, Soochow University, Suzhou 215123 (China); Yang Fan [College of Life Sciences, Soochow University, Suzhou 215123 (China); Zheng Lei [College of Life Sciences, Soochow University, Suzhou 215123 (China); Wang Xuefeng [College of Life Sciences, Soochow University, Suzhou 215123 (China); Liu Tao [Synchrotron Radiation Laboratory, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100039 (China); Xie Yaning [Synchrotron Radiation Laboratory, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100039 (China); Xu Jianhua [Synchrotron Radiation Laboratory, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100039 (China); Li Zhongrui [School of Chemical, Biological and Materials Engineering, University of Oklahoma (United States)

2006-03-31

274

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...

275

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

PubMed

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

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

2014-10-01

276

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

277

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

278

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

279

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

280

Significance of leaf orientation for leaf temperature in an Amazonian sclerophyll vegetation.  

PubMed

The influence of leaf orientation on leaf temperature has been studied in an sclerophyll vegetation of the Amazon basin, which grows on white sandy soils of very low water retention capacity and variable depth of the water table. Leaf size of the species studied is mainly mesophyllous (sensu Raunkiaer). The high degree of leaf inclination in all species is very characteristic; 55% of the leaves present inclination angles (relative to the vertical) smaller than 45 degrees. Water potential is generally high, not being lower than -14 bars. Leaf resistance increases toward noon during the course of sunny days, indicating either water stress at leaf level or the influence of low relative humidity on stomata opening. Leaf temperature under sunny conditions reflects the influence of leaf orientation on the amount of radiation absorbed by the leaf. Temperature differences recorded range from 1.8--5.4 degrees C. The difference depends on leaf angle, leaf color and leaf diffusion resistance during the period of measurement. Analysis of the relationship between leaf angle and leaf temperature, using Gates leaf energy balance, shows that under the conditions prevailing at noon in sunny days, leaf angles smaller than 50 degrees are effective in reducing leaf temperature within a wide range of leaf resistances to water vapor transfer. PMID:724979

Medina, E; Sobrado, M; Herrera, R

1978-08-10

281

Biochemical and proton NMR characterization of the isolated functional beta-subunit of coupling factor one from spinach chloroplasts  

SciTech Connect

Beta subunits have been dissociated from CF1 of spinach chloroplasts, purified by HPLC and characterized by two-dimensional electrophoresis and fluorescence emission. The solutions of isolated beta subunits are able to hydrolyze MgATP; this ATPase activity is an intrinsic property of the beta molecule. From proton NMR at 300 and 500 MHz, it is shown that the preparations are fully reproducible and that beta subunits remain monomeric with 75% aliphatic protons associated with rigid parts of the molecule. The other 25% give rise to separate resonances and belong to mobile side-chains and/or to flexible regions. The measurement of the transverse relaxation times T2 has permitted a detailed characterization of the molecular dynamics of the isolated beta subunits.

Roux-Fromy, M.; Neumann, J.M.; Andre, F.; Berger, G.; Girault, G.; Galmiche, J.M.; Remy, R.

1987-04-29

282

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

PubMed

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

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

2011-03-01

283

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

PubMed Central

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

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

2011-01-01

284

Leaf Senescence and GABA Shunt  

PubMed Central

Leaf senescence is highly regulated and complex developmental process that involves degradation of macromolecules as well as its recycling. Senescence process involves loss of chlorophyll, degradation of proteins, nucleic acid, lipid and mobilization of nutrients through its transport to the growing parts, developing fruits and seeds. Nitrogen is the most important nutrient to be recycled in senescence process. GABA-transaminase (?-aminobutyric acid) is found to play very important role in nitrogen recycling process through GABA-shunt. Therefore, it is of interest to review the significance of GABA shunt in leaf senescence.

Ansari, Mohammad Israil; Hasan, Saba; Jalil, Syed Uzma

2014-01-01

285

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.

286

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

287

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

288

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

289

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

290

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471...TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is...

2010-01-01

291

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Below Leaf Grade Cotton. 28.471 Section 28.471...TESTING, AND STANDARDS Standards Below Leaf Grade Cotton § 28.471 Below Leaf Grade Cotton. Below leaf grade cotton is...

2011-01-01

292

Spectral reflectance relationships to leaf water stress  

NASA Technical Reports Server (NTRS)

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

Ripple, William J.

1986-01-01

293

An Innovative Way to Monitor Leaf Age  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

294

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 2014-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2014-01-01

295

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2012-01-01

296

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2011-01-01

297

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2010-01-01

298

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Leaf tobacco. 30.2 Section 30.2 Agriculture...STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes, Types and Groups of...

2013-01-01

299

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

300

Remote estimation of leaf area index and green leaf biomass in maize canopies  

E-print Network

Remote estimation of leaf area index and green leaf biomass in maize canopies Anatoly A. Gitelson,1 750 nm). The technique was tested in agricultural fields under a maize canopy, and proved suitable of leaf area index and green leaf biomass in maize canopies, Geophys. Res. Lett., 30(5), 1248, doi:10

Gitelson, Anatoly

301

LEAF: A Microcomputer Program for Constructing the Tukey Stem and Leaf Graph.  

ERIC Educational Resources Information Center

This paper presents a BASIC microcomputer program that constructs the Tukey (1977) stem and leaf graph. Options within the LEAF program include a modified stem and leaf where the stem is split and a parallel stem and leaf graph where two separate sets of data are displayed from a common stem. (Author)

Pascale, Pietro J.; Smith, Joseph

1986-01-01

302

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

E-print Network

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

Paris-Sud XI, Université de

303

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

304

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

305

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

306

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

307

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

308

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...2 2010-01-01 2010-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture ...Fire-Cured Tobacco (u.s. Type 21) § 29.2278 Leaf structure. The cell development of a leaf as indicated by its...

2010-01-01

309

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

...2 2011-01-01 2011-01-01 false Leaf structure. 29.2278 Section 29.2278 Agriculture ...Fire-Cured Tobacco (u.s. Type 21) § 29.2278 Leaf structure. The cell development of a leaf as indicated by its...

2011-01-01

310

7 CFR 29.2277 - Leaf scrap.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

311

7 CFR 29.3034 - Leaf scrap.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

312

7 CFR 29.3034 - Leaf scrap.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

313

7 CFR 29.3034 - Leaf scrap.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture...Type 31 and Foreign Type 93) § 29.3034 Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed...

2010-01-01

314

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

315

7 CFR 29.3526 - Leaf scrap.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

316

7 CFR 29.2277 - Leaf scrap.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture...Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

2010-01-01

317

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

318

7 CFR 29.2277 - Leaf scrap.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

319

7 CFR 29.2278 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

320

On magnetic leaf-wise intersections  

E-print Network

In this article we introduce the notion of a magnetic leaf-wise intersection point which is a generalization of the leaf-wise intersection point with magnetic effects. We also prove the existence of magnetic leaf-wise intersection points under certain topological assumptions.

Bae, Youngjin

2011-01-01

321

7 CFR 29.2277 - Leaf scrap.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

322

7 CFR 29.2277 - Leaf scrap.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf scrap. 29.2277 Section 29.2277 Agriculture...Tobacco (u.s. Type 21) § 29.2277 Leaf scrap. A byproduct of unstemmed tobacco. Leaf scrap results from handling unstemmed...

2011-01-01

323

7 CFR 29.3526 - Leaf scrap.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

324

7 CFR 29.3034 - Leaf scrap.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf scrap. 29.3034 Section 29.3034 Agriculture...Type 31 and Foreign Type 93) § 29.3034 Leaf scrap. A by-product of unstemmed tobacco. Leaf scrap results from handling unstemmed...

2011-01-01

325

7 CFR 29.3526 - Leaf scrap.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

326

7 CFR 29.3526 - Leaf scrap.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf scrap. 29.3526 Section 29.3526 Agriculture...36, 37 and Foreign Type 95) § 29.3526 Leaf scrap. A byproduct of unstemmed tobacco Leaf scrap results from handling unstemmed...

2011-01-01

327

7 CFR 29.3034 - Leaf scrap.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

328

ORIGINAL PAPER Leaf wax d2  

E-print Network

ORIGINAL PAPER Leaf wax d2 H and varve-thickness climate proxies from proglacial lake sediments Science+Business Media B.V. 2012 Abstract We present a multiproxy paleoclimate record using leaf wax Á Leaf wax Á Proglacial lake Á Varve Introduction Arctic proglacial lake sediments are excellent

Briner, Jason P.

329

Leaf Sequencing Algorithms for Segmented Multileaf Collimation  

E-print Network

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

Sahni, Sartaj K.

330

Parameterized Algorithms for Directed Maximum Leaf Problems  

E-print Network

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

Krivelevich, Michael

331

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

332

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...

333

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

334

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

335

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

336

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

337

7 CFR 29.1162 - Leaf (B Group).  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

338

Changes in fungal community structure in bulk soil and spinach rhizosphere soil after chemical fumigation as revealed by 18S rDNA PCR-DGGE  

Microsoft Academic Search

To analyze the impact of chloropicrin and 1,3-dichloropropene on fungal community structure in bulk soil and spinach rhizosphere soil in a field, developed a new nested polymerase chain reaction (PCR) method to facilitate the detection of major fungal taxa and we used the method to monitor 18S rDNA PCR-denaturing gradient gel electrophoresis (DGGE) profiles for 3 years. The cropping system consisted

Yuko Takada Hoshino; Naoyuki Matsumoto

2007-01-01

339

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

PubMed

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

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

2013-11-01

340

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

SciTech Connect

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

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

1990-06-19

341

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

342

Influence of Lime and Organic Matter on the Mobility of Cadmium in Cadmium-Contaminated Soil in Relation to Nutrition of Spinach  

Microsoft Academic Search

Cadmium and cadmium compounds are water soluble, mobile in most soils, bio-available, and tend to bio-accumulate. A pot culture experiment was conducted on contaminated soil to study the influence of lime and organic matter on the mobility of cadmium in spinach and its rhizosphere soil. Application of lime (50% and 100% lime requirement) and organic matter (0.5 and 1% by

T. K. Pandit; S. K. Naik; P. K. Patra; D. K. Das

2012-01-01

343

Influence of lime and organic matter on the mobility of cadmium in cadmium contaminated soil in relation to nutrition of spinach  

Microsoft Academic Search

Cadmium and cadmium compounds are water soluble, mobile in most soils, bio-available and tend to bio-accumulate. A pot culture experiment was conducted on contaminated soil to study the influence of lime and organic matter on the mobility of cadmium in spinach and its rhizosphere soil. Application of lime (50% and 100% lime requirement) and organic matter (0.5 and 1% by

T. K. Pandit; S. K. Naik; P. K. Patra; D. K. Das

2012-01-01

344

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

345

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

PubMed

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

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

2014-08-01

346

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

347

If the antibody fails – a mass Western approach  

PubMed Central

Sucrose-phosphate synthase (SPS) has attracted the interest of plant scientists for decades. It is the key enzyme in sucrose metabolism and is under investigation in various plant species, e.g. spinach, tobacco, poplar, resurrection plants, maize, rice, kiwi and Arabidopsis thaliana. In A. thaliana, there are four distinct SPS isoforms. Their expression is thought to depend on environmental conditions and plant tissue. However, these data were derived from mRNA expression levels only. No data on SPS protein identification from crude extracts have been available until now. An antibody approach failed to distinguish the four isoforms. Therefore, we developed a method for SPS quantification and isoform-specific identification in A. thaliana complex protein samples. Samples were separated on SDS-PAGE, digested and directly applied to liquid chromatography/triple-stage quadrupole mass spectrometry (LC/TSQ-MS). In this approach, known as mass Western, samples were analysed in multi-reaction monitoring (MRM) mode, so that all four SPS isoforms could be measured in one experiment. In addition to the relative quantification, stable isotope-labelled internal peptide standards allowed absolute quantification of SPS proteins. Protein extracts from various plant tissues, samples harvested during the day or the night, and cold-stressed plants were analysed. The stress-specific SPS5a isoform showed increased concentrations in cold-stressed leaf material. PMID:18485062

Lehmann, Ute; Wienkoop, Stefanie; Tschoep, Hendrik; Weckwerth, Wolfram

2008-01-01

348

Inactivation of Escherichia coli O157:H7 and natural microbiota on spinach leaves using gaseous ozone during vacuum cooling and simulated transportation.  

PubMed

The aim of this study was to integrate an ozone-based sanitization step into existing processing practices for fresh produce and to evaluate the efficacy of this step against Escherichia coli O157:H7. Baby spinach inoculated with E. coli O157:H7 (approximately 10(7) CFU/g) was treated in a pilot-scale system with combinations of vacuum cooling and sanitizing levels of ozone gas (SanVac). The contribution of process variables (ozone concentration, pressure, and treatment time) to lethality was investigated using response-surface methodology. SanVac processes decreased E. coli O157:H7 populations by up to 2.4 log CFU/g. An optimized SanVac process that inactivated 1.8 log CFU/g with no apparent damage to the quality of the spinach had the following parameters: O3 at 1.5 g/kg gas-mix (935 ppm, vol/vol), 10 psig of holding pressure, and 30 min of holding time. In a separate set of experiments, refrigerated spinach was treated with low ozone levels (8 to 16 mg/kg; 5 to 10 ppm, vol/vol) for up to 3 days in a system that simulated sanitization during transportation (SanTrans). The treatment decreased E. coli populations by up to 1.4 log CFU/g, and the optimum process resulted in a 1.0-log inactivation with minimal effect on product quality. In a third group of experiments, freshly harvested unprocessed spinach was inoculated with E. coli O157:H7 and sequentially subjected to optimized SanVac and SanTrans processes. This double treatment inactivated 4.1 to > or = 5.0 log CFU/g, depending on the treatment time. These novel sanitization approaches were effective in considerably reducing the E. coli O157: H7 populations on spinach and should be relatively easy to integrate into existing fresh produce processes and practices. PMID:19681283

Vurma, Mustafa; Pandit, Ram B; Sastry, Sudhir K; Yousef, Ahmed E

2009-07-01

349

Electrowetting on a lotus leaf  

PubMed Central

Electrowetting on dielectrics has been widely used to manipulate and control microliter or nanoliter liquids in micro-total-analysis systems and laboratory on a chip. We carried out experiments on electrowetting on a lotus leaf, which is quite different from the equipotential plate used in conventional electrowetting. This has not been reported in the past. The lotus leaf is superhydrophobic and a weak conductor, so the droplet can be easily actuated on it through electrical potential gradient. The capillary motion of the droplet was recorded by a high-speed camera. The droplet moved toward the counterelectrode to fulfill the actuation. The actuation speed could be of the order of 10 mm?s. The actuation time is of the order of 10 ms. PMID:19693341

Feng, Jiang-Tao; Wang, Feng-Chao; Zhao, Ya-Pu

2009-01-01

350

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

PubMed Central

High throughput phenotyping (phenomics) is a powerful tool for linking genes to their functions (see review1 and recent examples2-4). Leaves are the primary photosynthetic organ, and their size and shape vary developmentally and environmentally within a plant. For these reasons studies on leaf morphology require measurement of multiple parameters from numerous leaves, which is best done by semi-automated phenomics tools5,6. Canopy shade is an important environmental cue that affects plant architecture and life history; the suite of responses is collectively called the shade avoidance syndrome (SAS)7. Among SAS responses, shade induced leaf petiole elongation and changes in blade area are particularly useful as indices8. To date, leaf shape programs (e.g. SHAPE9, LAMINA10, LeafAnalyzer11, LEAFPROCESSOR12) can measure leaf outlines and categorize leaf shapes, but can not output petiole length. Lack of large-scale measurement systems of leaf petioles has inhibited phenomics approaches to SAS research. In this paper, we describe a newly developed ImageJ plugin, called LeafJ, which can rapidly measure petiole length and leaf blade parameters of the model plant Arabidopsis thaliana. For the occasional leaf that required manual correction of the petiole/leaf blade boundary we used a touch-screen tablet. Further, leaf cell shape and leaf cell numbers are important determinants of leaf size13. Separate from LeafJ we also present a protocol for using a touch-screen tablet for measuring cell shape, area, and size. Our leaf trait measurement system is not limited to shade-avoidance research and will accelerate leaf phenotyping of many mutants and screening plants by leaf phenotyping. PMID:23380664

Mumbach, Maxwell R.; Palmer, Christine M.

2013-01-01

351

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

352

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

353

Nucleotide sequence of the gene for the P680 chlorophyll alpha apoprotein of the photosystem II reaction center from spinach.  

PubMed Central

The DNA sequence of 2210 nucleotides including the gene for the "51 kd" chlorophyll alpha-conjugated thylakoid membrane protein associated with the photosystem II reaction center of spinach has been determined. This protein is functionally identical with the P680 chlorophyll alpha apoprotein that catalyses the primary light-induced photochemical processes of photosystem II (Camm, E.L. and Green, B.R. (1983) Biochim. Biophys. Acta 724 291-293). The only large open reading frame in the sequence consists of 508 triplets encoding a protein of molecular mass of 56,246 kd. The deduced amino acid sequence shows clustering of hydrophobic residues into seven core regions which probably traverse the membrane, and a large hydrophilic domain of about 200 amino acids interspersed between span VI and VII. Potential transcription promotor and terminator signals flanking the structural gene show prokaryotic-like features. Seven discrete RNA species ranging in size from 2.0 to over 5.0 kilobases display complementarity to apoprotein coding sequences implying that the region can be polycistronically transcribed. The primary transcript includes information for at least two further genes coding for subunits of the cytochrome b/f complex. Images PMID:6324128

Morris, J; Herrmann, R G

1984-01-01

354

The Glyceraldehyde 3-Phosphate and Glycerate 3-Phosphate Shuttle and Carbon Dioxide Assimilation in Intact Spinach Chloroplasts 1  

PubMed Central

The regulation of CO2 assimilation by intact spinach (Spinacia oleracea) chloroplasts by exogenous NADP-linked nonreversible d-glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.9) was investigated. This dehydrogenase mediated a glyceraldehyde 3-phosphate/glycerate 3-phosphate shuttle for the indirect transfer of NADPH from chloroplast to the external medium. The rate of NADPH formation in the medium reflected glyceraldehyde 3-phosphate efflux from the chloroplast. Increasing enzyme concentrations stimulated NADP reduction and, in turn, CO2 fixation. Pyrophosphate increased CO2 fixation by apparently inhibiting glyceraldehyde 3-phosphate efflux. Increasing the glycerate 3-phosphate concentration above 0.1 mm stimulated glyceraldehyde 3-phosphate efflux but inhibited CO2 fixation. Addition of up to 0.5 mm orthophosphate enhanced both glyceraldehyde 3-phosphate efflux and CO2 fixation while each was inhibited by higher orthophosphate concentrations. The mechanism by which the extent of glyceraldehyde 3-phosphate efflux regulated the rate of CO2 fixation in chloroplasts was discussed. PMID:16659203

Bamberger, Elchanan S.; Ehrlich, Barry A.; Gibbs, Martin

1975-01-01

355

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

PubMed

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

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

2014-01-01

356

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

PubMed

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

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

2015-01-01

357

7 CFR 28.466 - Leaf Grade 6.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is...

2010-01-01

358

7 CFR 28.465 - Leaf Grade 5.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is...

2010-01-01

359

7 CFR 28.461 - Leaf Grade 1.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is...

2012-01-01

360

7 CFR 28.463 - Leaf Grade 3.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is...

2013-01-01

361

7 CFR 28.463 - Leaf Grade 3.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is...

2012-01-01

362

7 CFR 28.462 - Leaf Grade 2.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is...

2010-01-01

363

7 CFR 28.467 - Leaf Grade 7.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which...

2012-01-01

364

7 CFR 28.467 - Leaf Grade 7.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which...

2010-01-01

365

7 CFR 28.461 - Leaf Grade 1.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is...

2013-01-01

366

7 CFR 28.464 - Leaf Grade 4.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is...

2010-01-01

367

7 CFR 28.461 - Leaf Grade 1.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is...

2011-01-01

368

7 CFR 28.467 - Leaf Grade 7.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which...

2014-01-01

369

7 CFR 28.464 - Leaf Grade 4.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is...

2014-01-01

370

7 CFR 28.465 - Leaf Grade 5.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is...

2011-01-01

371

7 CFR 28.465 - Leaf Grade 5.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is...

2013-01-01

372

7 CFR 28.466 - Leaf Grade 6.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is...

2012-01-01

373

7 CFR 28.463 - Leaf Grade 3.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is...

2010-01-01

374

7 CFR 28.461 - Leaf Grade 1.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is...

2010-01-01

375

7 CFR 28.464 - Leaf Grade 4.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is...

2013-01-01

376

7 CFR 28.466 - Leaf Grade 6.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is...

2011-01-01

377

7 CFR 28.465 - Leaf Grade 5.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is...

2014-01-01

378

7 CFR 28.466 - Leaf Grade 6.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is...

2013-01-01

379

7 CFR 28.462 - Leaf Grade 2.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is...

2013-01-01

380

7 CFR 28.463 - Leaf Grade 3.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is...

2011-01-01

381

7 CFR 28.462 - Leaf Grade 2.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is...

2012-01-01

382

7 CFR 28.466 - Leaf Grade 6.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade 6. 28.466 Section 28.466 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.466 Leaf Grade 6. Leaf Grade 6 is leaf which is...

2014-01-01

383

7 CFR 28.464 - Leaf Grade 4.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is...

2012-01-01

384

7 CFR 28.467 - Leaf Grade 7.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which...

2013-01-01

385

7 CFR 28.461 - Leaf Grade 1.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade 1. 28.461 Section 28.461 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.461 Leaf Grade 1. Leaf Grade 1 is leaf which is...

2014-01-01

386

7 CFR 28.462 - Leaf Grade 2.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is...

2011-01-01

387

7 CFR 28.464 - Leaf Grade 4.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade 4. 28.464 Section 28.464 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.464 Leaf Grade 4. Leaf Grade 4 is leaf which is...

2011-01-01

388

7 CFR 28.462 - Leaf Grade 2.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade 2. 28.462 Section 28.462 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.462 Leaf Grade 2. Leaf Grade 2 is leaf which is...

2014-01-01

389

7 CFR 28.467 - Leaf Grade 7.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade 7. 28.467 Section 28.467 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which...

2011-01-01

390

7 CFR 28.463 - Leaf Grade 3.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade 3. 28.463 Section 28.463 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.463 Leaf Grade 3. Leaf Grade 3 is leaf which is...

2014-01-01

391

7 CFR 28.465 - Leaf Grade 5.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade 5. 28.465 Section 28.465 Agriculture...Cotton Standards of the United States for the Leaf Grade of American Upland Cotton § 28.465 Leaf Grade 5. Leaf Grade 5 is leaf which is...

2012-01-01

392

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

393

Changes in leaf hydraulic conductance during leaf shedding in seasonally dry tropical forest  

Microsoft Academic Search

Summary • The hydraulic conductance of leaves ( k leaf ) was examined to determine whether this little understood component of the water transport pathway plays a role in governing leaf phenology of two deciduous dry forest trees ( Calycophyllum candidissimum and Rhedera trinervis ). • k leaf was monitored in parallel with stem hydraulic conductivity (K stem ) during

T. J. Brodribb; N. M. Holbrook

2003-01-01

394

ORIGINAL PAPER Leaf age and the timing of leaf abscission in two tropical dry  

E-print Network

of external factors alone (van Schaik et al. 1993; Borchert 1994; Reich 1995), suggesting that the internal. graveolens, the initiation of leaf shedding followed in rank order, the maximum leaf age of the four species and the synchrony in the timing of phenological events such as leaf fall and bud break is low

Holbrook, N. Michele

395

Analysis on leaf-stripping effect of sugarcane feeding way for centrifugal leaf-stripping machine  

Microsoft Academic Search

The feeding way of sugarcane influenced the leaf-striping effect for the centrifugal type leaf -stripping machine. In this paper, two feeding ways, fed from root and top of sugarcane stalk, were analyzed by using the method of theoretical analysis and test. The influence of structure and morphology of sugarcane leaves, the motion state of sugarcane stalks in leaf -stripping process

Mou Xiangwei; Ou Yinggang; Liu Qingting; Zeng Zhiqiang

2011-01-01

396

Leaf emergence in relation to leaf traits in temperate woody species in East-Chinese Quercus fabri forests  

NASA Astrophysics Data System (ADS)

To determine the effect of leaf traits on leaf emergence phenology, timing of leaf emergence, leaf expansion rate, durations of leaf emergence and expansion, leaf mass per area (LMA) and leaf size were investigated for 48 woody species from 25 families in two closed Chinese white oak ( Quercus fabri) forests of eastern China. Cross-species regression and phylogenetic regression were employed to examine the relationship between leaf phenology and leaf traits. Leaf area, LMA, and leaf expansion rate were found to be significantly greater in canopy trees than in understory shrubs in the oak forests. However, there was no significant difference in timing of leaf emergence and durations of leaf emergence and expansion between canopy and understory species. The large-LMA species leafed out earlier than the species with small LMA. The small-leaved species leafed out earlier than the species with large leaves, but the large-leaved species were greater in leaf expansion rate than their counterparts. Leaf expansion rate was positively correlated with leaf area and timing of leaf emergence, but no significant relationship was found between leaf size and leaf expansion period. These results suggest that large- and small-leaved species possibly employed different strategies to minimize herbivory damage, i.e. early leafing to avoid defoliator damage in small-leaved species and fast expanding and thereby shortening vulnerable time to herbivores in large-leaved species. It could be inferred that the species with small leaves and large-LMA leafed out early in the oak forests, thereby permitting less energy loss than their counterparts under the influence of frost in early spring. In general, early leaf emergence is of significance for high LMA species to increase carbon gain in temperate broad-leaved forests, but it is not related to plant height. Leaf size and leaf expansion period are not necessarily correlated.

Sun, Shucun; Jin, Dongmei; Li, Rongjin

2006-09-01

397

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

NASA Astrophysics Data System (ADS)

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

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

2005-01-01

398

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

PubMed

"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

399

“Breath figures” on leaf surfaces—formation 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

400

Quantifying the Reduction in Potential Health Risks by Determining the Sensitivity of Poliovirus Type 1 Chat Strain and Rotavirus SA-11 to Electron Beam Irradiation of Iceberg Lettuce and Spinach  

PubMed Central

Fresh produce, such as lettuce and spinach, serves as a route of food-borne illnesses. The U.S. FDA has approved the use of ionizing irradiation up to 4 kGy as a pathogen kill step for fresh-cut lettuce and spinach. The focus of this study was to determine the inactivation of poliovirus and rotavirus on lettuce and spinach when exposed to various doses of high-energy electron beam (E-beam) irradiation and to calculate the theoretical reduction in infection risks that can be achieved under different contamination scenarios and E-beam dose applications. The D10 value (dose required to reduce virus titers by 90%) (standard error) of rotavirus on spinach and lettuce was 1.29 (± 0.64) kGy and 1.03 (± 0.05) kGy, respectively. The D10 value (standard error) of poliovirus on spinach and lettuce was 2.35 (± 0.20) kGy and 2.32 (± 0.08) kGy, respectively. Risk assessment of data showed that if a serving (?14 g) of lettuce was contaminated with 10 PFU/g of poliovirus, E-beam irradiation at 3 kGy will reduce the risk of infection from >2 in 10 persons to approximately 6 in 100 persons. Similarly, if a serving size (?0.8 g) of spinach is contaminated with 10 PFU/g of rotavirus, E-beam irradiation at 3 kGy will reduce infection risks from >3 in 10 persons to approximately 5 in 100 persons. The results highlight the value of employing E-beam irradiation to reduce public health risks but also the critical importance of adhering to good agricultural practices that limit enteric virus contamination at the farm and in packing houses. PMID:22179244

Espinosa, Ana Cecilia; Jesudhasan, Palmy; Arredondo, René; Cepeda, Martha; Mazari-Hiriart, Marisa; Mena, Kristi D.

2012-01-01

401

Kinetics and equilibria of active site core extrusion from spinach ferredoxin in aqueous N,N-dimethylformamide/Triton X-100 solutions.  

PubMed

The nature and reactivity of each species participating in core extrusion of the [2Fe-2S] cluster of spinach ferredoxin by benzenethiol have been investigated in a novel aqueous medium containing 10-40% (v/v) N,N-dimethylformamide (DMF) plus 5-6% (v/v) of the nonionic detergent, Triton X-100. By use of visible absorption and circular dichroism spectroscopies, it is found that prior to addition of benzenethiol, modifications of the ferredoxin induced by DMF are reversible. Both the extent and rate of modification are dependent on DMF concentration and on ionic strength. At ferredoxin concentrations near 0.1 mM, complete modification by DMF is shown to be unnecessary for quantitative core extrusion provided that the benzenethiol concentration is greater than or equal to 50 mM and the DMF concentration is greater than or equal to 10% (v/v). When benzenethiol is added after DMF, core extrusion occurs in two phases. Our interpretation is that the rapid phase corresponds to core extrusion of that portion of the ferredoxin already modified by DMF and that the slower phase corresponds to modification of the remaining portion of the ferredoxin by DMF. When DMF solutions containing benzenethiol and Triton X-100 in various ratios are mixed with aqueous solutions of spinach ferredoxin, the rate of core extrusion appears to be determined both by the rate at which the ferredoxin is modified and by the Triton/benzenethiol ratio. Under all conditions examined we observe significantly faster rates of core extrusion from spinach ferredoxin in aqueous Triton/DMF than in 80/20 (v/v) hexamethylphosphoramide/water, a previously used core extrusion medium. Our results suggest a catalytic role for the micellar phase. PMID:7159566

Bonomi, F; Kurtz, D M

1982-12-21

402

LSD: a leaf senescence database  

PubMed Central

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

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

2011-01-01

403

Reduction of bacteria on spinach, lettuce, and surfaces in food service areas using neutral electrolyzed oxidizing water.  

PubMed

Food safety issues and increases in food borne illnesses have promulgated the development of new sanitation methods to eliminate pathogenic organisms on foods and surfaces in food service areas. Electrolyzed oxidizing water (EO water) shows promise as an environmentally friendly broad spectrum microbial decontamination agent. EO water is generated by the passage of a dilute salt solution ( approximately 1% NaCl) through an electrochemical cell. This electrolytic process converts chloride ions and water molecules into chlorine oxidants (Cl(2), HOCl/ClO(-)). At a near-neutral pH (pH 6.3-6.5), the predominant chemical species is the highly biocidal hypochlorous acid species (HOCl) with the oxidation reduction potential (ORP) of the solution ranging from 800 to 900mV. The biocidal activity of near-neutral EO water was evaluated at 25 degrees C using pure cultures of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Treatment of these organisms, in pure culture, with EO water at concentrations of 20, 50, 100, and 120ppm total residual chlorine (TRC) and 10min of contact time resulted in 100% inactivation of all five organisms (reduction of 6.1-6.7log(10)CFU/mL). Spray treatment of surfaces in food service areas with EO water containing 278-310ppm TRC (pH 6.38) resulted in a 79-100% reduction of microbial growth. Dip (10min) treatment of spinach at 100 and 120ppm TRC resulted in a 4.0-5.0log(10)CFU/mL reduction of bacterial counts for all organisms tested. Dipping (10min) of lettuce at 100 and 120ppm TRC reduced bacterial counts of E. coli by 0.24-0.25log(10)CFU/mL and reduced all other organisms by 2.43-3.81log(10)CFU/mL. PMID:17993375

Guentzel, Jane L; Liang Lam, Kang; Callan, Michael A; Emmons, Stuart A; Dunham, Valgene L

2008-02-01

404

Inhibition of Photosynthetic Electron Transport in Isolated Spinach Chloroplasts by Two 1,3,4-Thiadiazolyl Derivatives 1  

PubMed Central

Buthidazole (3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone) and tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N?-dimethylurea) are two new promising herbicides for selective weed control in corn (Zea mays L.) and sugarcane (Saccharum officinarum L.), respectively. The effects of these two compounds on various photochemical reactions of isolated spinach (Spinacia oleracea L.) chloroplasts were studied at concentrations of 0, 0.05, 0.5, 5, and 500 micromolar. Buthidazole and tebuthiuron at concentrations higher than 0.5 micromolar inhibited uncoupled electron transport from water to ferricyanide or to methyl viologen very strongly. Photosystem II-mediated transfer of electrons from water to oxidized diamonodurene, with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) blocking photosystem I, was inhibited 34 and 37% by buthidazole and tebuthiuron, respectively, at 0.05 micromolar. Inhibition of photosystem I-mediated transfer of electrons from diaminodurene to methyl viologen with 3,4-dichlorophenyl-1,1-dimethylurea (DCMU) blocking photosystem II was insignificant with either herbicide at all concentrations tested. Transfer of electrons from catechol to methyl viologen in hydroxylamine-washed chloroplasts was inhibited 50 and 47% by buthidazole and tebuthiuron, respectively, at 0.5 micromolar. The data indicate that the inhibition of electron transport by both herbicides is primarily at the reducing side of photosystem II. However, since catechol is an electron donor at the oxidizing side of photosystem II, between water and chlorophyll a680, and lower inhibition levels were observed in the last study (catechol to methyl viologen), it may be that there is also a small inhibition of the mechanism of water oxidation by both herbicides. PMID:16661181

Hatzios, Kriton K.; Penner, Donald; Bell, Duncan

1980-01-01

405

Multiple complexes of nitrogen assimilatory enzymes in spinach chloroplasts: possible mechanisms for the regulation of enzyme function.  

PubMed

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

406

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

407

Influence of pH upon the Warburg effect in isolated intact spinach chloroplasts. I. Carbon dioxide photoassimilation and glycolate synthesis  

Microsoft Academic Search

The influence of pH upon the Oâ inhibition of ¹⁴COâ photoassimilation (Warburg effect) was examined in intact spinach (Spinacia oleracea) chloroplasts. With conditions which favored the Warburg effect, i.e. rate-limiting COâ and 100 percent Oâ, Oâ inhibition was greater at pH 8.4 to 8.5 than at pH 7.5 to 7.8. At pH 8.5, as compared with 7.8, there was an

J. M. Robinson; M. Gibbs; D. N. Cotler

1977-01-01

408

Location of enzymes metabolising sucrose and starch in the grasses Pennisetum purpureum and Muhlenbergia montana  

Microsoft Academic Search

Leaf tissue of the panicoid grass Pennisetum purpureum (Schum) and of the chloridoid grass Muhlenbergia montana (Hitchcock) were fractionated to produce preparations enriched in the contents of mesophyll and bundle sheath cells. Sucrose phosphate synthetase and sucrose synthetase were found predominantly in the mesophyll tissues of both species, as was uridine-diphosphate-glucose pyrophosphorylase in Pennisetum. In Muhlenbergia this enzyme was more

C. Bucke; I. R. Oliver

1975-01-01

409

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

410

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...u.s. Type 31 and Foreign Type 93) § 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements of quality.) [24 FR 8771, Oct. 29, 1959. Redesignated at 49 FR 16758, Apr. 20,...

2010-01-01

411

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...11, 12, 13, 14 and Foreign Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984,...

2010-01-01

412

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

...11, 12, 13, 14 and Foreign Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984,...

2013-01-01

413

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

...Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2601.) [37 FR 13626, July 12, 1972. Redesignated at 49 FR 16757, Apr. 20,...

2012-01-01

414

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

...Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality, § 29.3586.) [30 FR 9207, July 23, 1965. Redesignated at 49 FR 16759, Apr. 20,...

2012-01-01

415

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

...u.s. Type 31 and Foreign Type 93) § 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements of quality.) [24 FR 8771, Oct. 29, 1959. Redesignated at 49 FR 16758, Apr. 20,...

2014-01-01

416

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

...u.s. Type 31 and Foreign Type 93) § 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements of quality.) [24 FR 8771, Oct. 29, 1959. Redesignated at 49 FR 16758, Apr. 20,...

2013-01-01

417

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

...u.s. Type 31 and Foreign Type 93) § 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements of quality.) [24 FR 8771, Oct. 29, 1959. Redesignated at 49 FR 16758, Apr. 20,...

2011-01-01

418

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

...Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality, § 29.3586.) [30 FR 9207, July 23, 1965. Redesignated at 49 FR 16759, Apr. 20,...

2013-01-01

419

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

...Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2601.) [37 FR 13626, July 12, 1972. Redesignated at 49 FR 16757, Apr. 20,...

2014-01-01

420

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2013 CFR

...Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell development of a leaf as indicated by its porosity. (See chart, § 29.2601.) [37 FR 13626, July 12, 1972. Redesignated at 49 FR 16757, Apr. 20,...

2013-01-01

421

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

...11, 12, 13, 14 and Foreign Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984,...

2011-01-01

422

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

...11, 12, 13, 14 and Foreign Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984,...

2014-01-01

423

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

...Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality, § 29.3586.) [30 FR 9207, July 23, 1965. Redesignated at 49 FR 16759, Apr. 20,...

2011-01-01

424

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

...11, 12, 13, 14 and Foreign Type 92) § 29.1030 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality Chart.) [42 FR 21092, Apr. 25, 1977. Redesignated at 49 FR 16755, Apr. 20, 1984,...

2012-01-01

425

7 CFR 29.3035 - Leaf structure.  

Code of Federal Regulations, 2012 CFR

...u.s. Type 31 and Foreign Type 93) § 29.3035 Leaf structure. The cell development of a leaf as indicated by its porosity or solidity. (See Elements of quality.) [24 FR 8771, Oct. 29, 1959. Redesignated at 49 FR 16758, Apr. 20,...

2012-01-01

426

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2014 CFR

...Types 35, 36, 37 and Foreign Type 95) § 29.3527 Leaf structure. The cell development of a leaf as indicated by its porosity. (See Elements of Quality, § 29.3586.) [30 FR 9207, July 23, 1965. Redesignated at 49 FR 16759, Apr. 20,...

2014-01-01

427

The red edge of plant leaf reflectance  

Microsoft Academic Search

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

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

1983-01-01

428

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 ...

429

7 CFR 29.1029 - Leaf scrap.  

Code of Federal Regulations, 2011 CFR

... Agriculture 2 2011-01-01 2011-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations...Types 11, 12, 13, 14 and Foreign Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco....

2011-01-01

430

7 CFR 29.1029 - Leaf scrap.  

Code of Federal Regulations, 2010 CFR

... Agriculture 2 2010-01-01 2010-01-01 false Leaf scrap. 29.1029 Section 29.1029 Agriculture Regulations...Types 11, 12, 13, 14 and Foreign Type 92) § 29.1029 Leaf scrap. A byproduct of stemmed and unstemmed tobacco....

2010-01-01

431

7 CFR 29.1029 - Leaf scrap.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

432

7 CFR 29.1029 - Leaf scrap.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

433

7 CFR 29.1029 - Leaf scrap.  

Code of Federal Regulations, 2014 CFR

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

2014-01-01

434

Global patterns of leaf mechanical properties.  

PubMed

Leaf mechanical properties strongly influence leaf lifespan, plant-herbivore interactions, litter decomposition and nutrient cycling, but global patterns in their interspecific variation and underlying mechanisms remain poorly understood. We synthesize data across the three major measurement methods, permitting the first global analyses of leaf mechanics and associated traits, for 2819 species from 90 sites worldwide. Key measures of leaf mechanical resistance varied c. 500-800-fold among species. Contrary to a long-standing hypothesis, tropical leaves were not mechanically more resistant than temperate leaves. Leaf mechanical resistance was modestly related to rainfall and local light environment. By partitioning leaf mechanical resistance into three different components we discovered that toughness per density contributed a surprisingly large fraction to variation in mechanical resistance, larger than the fractions contributed by lamina thickness and tissue density. Higher toughness per density was associated with long leaf lifespan especially in forest understory. Seldom appreciated in the past, toughness per density is a key factor in leaf mechanical resistance, which itself influences plant-animal interactions and ecosystem functions across the globe. PMID:21265976

Onoda, Yusuke; Westoby, Mark; Adler, Peter B; Choong, Amy M F; Clissold, Fiona J; Cornelissen, Johannes H C; Díaz, Sandra; Dominy, Nathaniel J; Elgart, Alison; Enrico, Lucas; Fine, Paul V A; Howard, Jerome J; Jalili, Adel; Kitajima, Kaoru; Kurokawa, Hiroko; McArthur, Clare; Lucas, Peter W; Markesteijn, Lars; Pérez-Harguindeguy, Natalia; Poorter, Lourens; Richards, Lora; Santiago, Louis S; Sosinski, Enio E; Van Bael, Sunshine A; Warton, David I; Wright, Ian J; Wright, S Joseph; Yamashita, Nayuta

2011-03-01

435

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

436

Changes in Leaf Trichomes and Epicuticular Flavonoids during Leaf Development in Three Birch Taxa  

PubMed Central

• Background and Aims Changes in number of trichomes and in composition and concentrations of their exudates throughout leaf development may have important consequences for plant adaptation to abiotic and biotic factors. In the present study, seasonal changes in leaf trichomes and epicuticular flavonoid aglycones in three Finnish birch taxa (Betula pendula, B. pubescens ssp. pubescens, and B. pubescens ssp. czerepanovii) were followed. • Methods Trichome number and ultrastructure were studied by means of light, scanning and transmission electron microscopy, while flavonoid aglycones in ethanolic leaf surface extracts were analysed by high-pressure liquid chromatography. • Key Results Density of both glandular and non-glandular trichomes decreased drastically with leaf expansion while the total number of trichomes per leaf remained constant, indicating that the final number of trichomes is established early in leaf development. Cells of glandular trichomes differentiate before those of the epidermis and produce secreted material only during the relatively short period (around 1–2 weeks) of leaf unfolding and expansion. In fully expanded leaves, glandular trichomes appeared to be at the post-secretory phase and function mainly as storage organs; they contained lipid droplets and osmiophilic material (probably phenolics). Concentrations (mg g?1 d. wt) of surface flavonoids decreased with leaf age in all taxa. However, the changes in total amount (µg per leaf) of flavonoids during leaf development were taxon-specific: no changes in B. pubescens ssp. czerepanovii, increase in B. pendula and in B. pubescens ssp. pubescens followed by the decline in the latter taxon. Concentrations of most of the individual leaf surface flavonoids correlated positively with the density of glandular trichomes within species, suggesting the participation of glandular trichomes in production of surface flavonoids. • Conclusions Rapid decline in the density of leaf trichomes and in the concentrations of flavonoid aglycones with leaf age suggests that the functional role of trichomes is likely to be most important at the early stages of birch leaf development. PMID:15238348

VALKAMA, ELENA; SALMINEN, JUHA-PEKKA; KORICHEVA, JULIA; PIHLAJA, KALEVI

2004-01-01

437

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

Microsoft Academic Search

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

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

1997-01-01

438

LEAF-NODULE SYMBIOSIS I.  

PubMed Central

Centifanto, Ysolina M. (University of Florida, Gainesville), and Warren S. Silver. Leafnodule symbiosis. I. Endophyte of Psychotria bacteriophila. J. Bacteriol. 88:776–781. 1964.—The leaf-nodule endophyte of Psychotria bacteriophila has been repeatedly isolated in pure culture from germinating seedlings and young leaves on a nitrogen-free mineral agar. Its morphological, serological, and cultural characteristics place it within the Klebsiella-Aerobacter group. The endophyte has been provisionally named Klebsiella rubiacearum. Pure cultures fix N2 under anaerobic conditions with good efficiency (4.54 ?g of N fixed/mg of glucose utilized in 3 days). Nitrogen fixation by pure cultures is intimately related to pyruvate and hydrogen metabolism. Images PMID:14208518

Centifanto, Ysolina M.; Silver, Warren S.

1964-01-01

439

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

440

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

PubMed

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

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

2013-09-01

441

Effect of Photoperiod on the Levels of Endogenous Gibberellins in Spinach as Measured by Combined Gas Chromatography-selected Ion Current Monitoring 1  

PubMed Central

The changes in the levels of five endogenous gibberellins (GAs) in spinach in relation to photoperiodic treatment have been examined by combined gas chromatography-selected ion current monitoring. Long-day treatment caused a 5-fold decline in the level of GA19 while the levels of GA20 and GA29 increased dramatically during the same period. In absolute terms, the level of GA20 increased from 0.8 microgram per 100 grams dry weight in short days to 5.5 micrograms per 100 grams dry weight after 14 long days. The levels of GA17 and GA44 did not change significantly with long-day treatment. These results are consistent with the hypothesis that GA19 is converted to GA20 and that this conversion is under photoperiodic control. Since stem growth in spinach is correlated with an increase in the level of GA20, one major aspect of photoperiodic control of stem growth might be the availability of GA20 through regulation of the conversion of GA19 to GA20. PMID:16661539

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

1980-01-01

442

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

443

Photobleaching with phloxine B sensitizer to reduce food matrix interference for detection of Escherichia coli serotype O157:H7 in fresh spinach by flow cytometry.  

PubMed

A flow cytometric method (RAPID-B™) with detection sensitivity of one viable cell of Escherichia coli serotype O157:H7 in fresh spinach (Spinacia oleracea) was developed and evaluated. The major impediment to achieving this performance was mistaking autofluorescing spinach particles for tagged target cells. Following a 5 h non-selective enrichment, artificially inoculated samples were photobleached, using phloxine B as a photosensitizer. Samples were centrifuged at high speed to concentrate target cells, then gradient centrifuged to separate them from matrix debris. In external laboratory experiments, RAPID-B and the reference method both correctly detected E. coli O157:H7 at inoculations of ca. 15 cells. In a follow-up study, after 4 cell inoculations of positives and 6 h enrichment, RAPID-B correctly identified 92% of 25 samples. The RAPID-B method limit of detection (LOD) was one cell in 25 g. It proved superior to the reference method (which incorporated real time-PCR, selective enrichment, and culture plating elements) in accuracy and speed. PMID:24010624

Buzatu, Dan A; Cooper, Willie M; Summage-West, Christine; Sutherland, John B; Williams, Anna J; Bass, Deborah A; Smith, Lisa L; Woodruff, Robert S; Christman, Jessica M; Reid, Steven; Tucker, Randal K; Haney, Christopher J; Ahmed, Ashfaqe; Rafii, Fatemeh; Wilkes, Jon G

2013-12-01

444

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

445

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

446

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Smoking Leaf (H Group). 29.1163 Section...INSPECTION Standards Grades § 29.1163 Smoking Leaf (H Group). This group...Tolerances H3F—Good Quality Orange Smoking Leaf Mellow, open leaf...

2011-01-01

447

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 H3F—Good Quality Orange Smoking Leaf Mellow, open leaf...

2010-01-01

448

Changes in photosynthetic characteristics during leaf development in apple  

Microsoft Academic Search

A comprehensive developmental survey of leaf area, chlorophyll, photosynthetic rate, leaf resistance, transpiration ratio, CO2 compensation point and photorespiration was conducted in apple. The largest changes in each of the photosynthetic characteristics studied took place during the earliest stages of leaf development, coinciding with the period of greatest leaf expansion and chlorophyll synthesis. During early development, photosynthesis increased 5-fold, reaching

Robert A. Kennedy; Diane Johnson

1981-01-01

449

Elevated COâ 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) COâ levels. Leaves of elevated COâ plants exhibited more deeply incised leaf margins and relatively more slender leaf laminae than leaves of ambient COâ 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

450

7 CFR 28.515 - Leaf Grade No. 5.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall...

2010-01-01

451

7 CFR 28.511 - Leaf Grade No. 1.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall...

2014-01-01

452

7 CFR 28.511 - Leaf Grade No. 1.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall...

2012-01-01

453

7 CFR 28.511 - Leaf Grade No. 1.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall...

2010-01-01

454

7 CFR 28.512 - Leaf Grade No. 2.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall...

2010-01-01

455

7 CFR 28.513 - Leaf Grade No. 3.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall...

2013-01-01

456

7 CFR 28.512 - Leaf Grade No. 2.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall...

2014-01-01

457

7 CFR 28.514 - Leaf Grade No. 4.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall...

2014-01-01

458

7 CFR 28.516 - Leaf Grade No. 6.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall...

2012-01-01

459

7 CFR 28.515 - Leaf Grade No. 5.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall...

2014-01-01

460

7 CFR 28.512 - Leaf Grade No. 2.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall...

2011-01-01

461

7 CFR 28.514 - Leaf Grade No. 4.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall...

2011-01-01

462

7 CFR 28.512 - Leaf Grade No. 2.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall...

2012-01-01

463

7 CFR 28.514 - Leaf Grade No. 4.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall...

2012-01-01

464

7 CFR 28.515 - Leaf Grade No. 5.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall...

2012-01-01

465

7 CFR 28.515 - Leaf Grade No. 5.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall...

2011-01-01

466

7 CFR 28.514 - Leaf Grade No. 4.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade No. 4. 28.514 Section 28.514...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall...

2013-01-01

467

7 CFR 28.515 - Leaf Grade No. 5.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade No. 5. 28.515 Section 28.515...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall...

2013-01-01

468

7 CFR 28.513 - Leaf Grade No. 3.  

Code of Federal Regulations, 2012 CFR

... 2012-01-01 2012-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall...

2012-01-01

469

7 CFR 28.516 - Leaf Grade No. 6.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall...

2011-01-01

470

7 CFR 28.516 - Leaf Grade No. 6.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall...

2014-01-01

471

7 CFR 28.513 - Leaf Grade No. 3.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall...

2010-01-01

472

7 CFR 28.516 - Leaf Grade No. 6.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade No. 6. 28.516 Section 28.516...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall...

2013-01-01

473

7 CFR 28.513 - Leaf Grade No. 3.  

Code of Federal Regulations, 2014 CFR

... 2014-01-01 2014-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall...

2014-01-01

474

7 CFR 28.511 - Leaf Grade No. 1.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall...

2013-01-01

475

7 CFR 28.513 - Leaf Grade No. 3.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade No. 3. 28.513 Section 28.513...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.513 Leaf Grade No. 3. Leaf grade No. 3 shall...

2011-01-01

476

7 CFR 28.512 - Leaf Grade No. 2.  

Code of Federal Regulations, 2013 CFR

... 2013-01-01 2013-01-01 false Leaf Grade No. 2. 28.512 Section 28.512...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall...

2013-01-01

477

7 CFR 28.511 - Leaf Grade No. 1.  

Code of Federal Regulations, 2011 CFR

... 2011-01-01 2011-01-01 false Leaf Grade No. 1. 28.511 Section 28.511...Cotton Standards of the United States for the Leaf Grade of American Pima Cotton § 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall...

2011-01-01

478

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

479

Purdue extensionGray Leaf Spot Purdue extension  

E-print Network

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

480

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

481

Leaf Deformation Taking Into Account Fluid Flow Paulo Silva  

E-print Network

Leaf Deformation Taking Into Account Fluid Flow Paulo Silva The University of Tokyo Yonghao Yue--This paper proposes a method for animating leaf structural deformation considering the leaf water content the leaf, and couple the mass-spring parameters with a simulation representing the fluid flow

Ouhyoung, Ming

482

Effect of Image Processing of a Leaf Photograph on the Calculated Fractal Dimension of Leaf Veins  

Microsoft Academic Search

Digital photography is a promised method for estimating the fractal characteristics of leaf veins. In this study, the effects\\u000a of different threshold levels and image processing methods using Adobe Photoshop software on the fractal dimension values\\u000a were examined from a digital photo of nectarine leaf. The results showed that the nectarine leaf vein has typical fractal\\u000a characteristics and its fractal

Yun Kong; Shaohui Wang; Chengwei Ma; Baoming Li; Yuncong Yao

2007-01-01

483

Guava leaf extract and topical haemostasis.  

PubMed

The effects of guava leaf extract on the bleeding time and the three main mechanisms of haemostasis: vasoconstriction, platelet aggregation and blood coagulation, were investigated. The water extract of guava leaves did not shorten bleeding times in rats. Guava leaf extract potentiated the vascular muscle contraction induced in rabbits by phenylephrine, and when given alone it stimulated human platelet aggregation in vitro in a dose-dependent manner. On the other hand, it significantly prolonged blood coagulation; activated partial thromboplastin time (APTT) test (p < 0.05). The higher the concentration of the extract, the longer APTT was observed. Thus, a water extract of guava leaves showed ambiguous effects on the haemostatic system. Guava leaf extract did not affect bleeding times, it stimulated vasoconstriction and platelet aggregation but it inhibited blood coagulation. Therefore, guava leaf extract is not recommended as a haemostatic agent. PMID:10925412

Jaiarj, P; Wongkrajang, Y; Thongpraditchote, S; Peungvicha, P; Bunyapraphatsara, N; Opartkiattikul, N

2000-08-01

484

Spectroscopic Measurement of Leaf Water Status  

NASA Technical Reports Server (NTRS)

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

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

1995-01-01

485

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

486

7 CFR 29.2529 - Leaf scrap.  

Code of Federal Regulations, 2011 CFR

...REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2529 Leaf scrap. A byproduct...

2011-01-01

487

7 CFR 29.2528 - Leaf.  

Code of Federal Regulations, 2010 CFR

...REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2528 Leaf. Whole, unstemmed...

2010-01-01

488

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell...

2010-01-01

489

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2011 CFR

...REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Kentucky and Tennessee Fire-Cured and Foreign-Grown Fire-Cured Tobacco (u.s. Types 22, 23, and Foreign Type 96) § 29.2530 Leaf structure. The cell...

2011-01-01

490

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

491

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.

Greb, Stephen

492

Antibacterial activity on Citrullus colocynthis Leaf extract.  

PubMed

Studies on the antibacterial activities of the leaf extract of Citrullus colocynthis (Cucurbitaceae), a medicinal plant used for the treatment of various ailments was carried out using agar disc diffusion technique. The results revealed that the crude acetone extract exhibited antibacterial activities against Pseudomonas aeruginosa with zones of inhibition measuring 14.0mm. The chloroform leaf extract exhibited no antibacterial activity against Staphylococcus aureus. The minimum inhibitory concentration for the chloroform extract was 4.0mm for Escherichia coli. PMID:22557336

Gowri, S Shyamala; Priyavardhini, S; Vasantha, K; Umadevi, M

2009-07-01

493

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

494

Remote sensing of leaf water status  

NASA Technical Reports Server (NTRS)

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

Ripple, William J.; Schrumpf, Barry J.

1987-01-01

495

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

496

Single Leaf Area Measurement Using Digital Camera Image  

Microsoft Academic Search

\\u000a Leaf area index is one of the most important parameters in ecological and environmental studies. This paper presents a method\\u000a for single leaf area measurement based on the counting of the leaf pixels in digital leaf image. Initially, the target leaf\\u000a is put on a piece of white paper on which four endpoints of an equal-length and orthogonal cross are

Baisong Chen; Zhuo Fu; Yuchun Pan; Jihua Wang; Zhixuan Zeng

2010-01-01

497

Root Hypoxia Reduces Leaf Growth 1  

PubMed Central

This study examined the potential role of restricted phloem export, or import of substances from the roots in the leaf growth response to root hypoxia. In addition, the effects of root hypoxia on abscisic acid (ABA) and zeatin riboside (ZR) levels were measured and their effects on in vitro growth determined. Imposition of root hypoxia in the dark when transpirational water flux was minimal delayed the reduction in leaf growth until the following light period. Restriction of phloem transport by stem girdling did not eliminate the hypoxia-induced reduction in leaf growth. In vitro growth of leaf discs was inhibited in the presence of xylem sap collected from hypoxic roots, and also by millimolar ABA. Disc growth was promoted by sap from aerated roots and by 0.1 micromolar ZR. The flux of both ABA and ZR was reduced in xylem sap from hypoxic roots. Leaf ABA transiently increased twofold after 24 hours of hypoxia exposure but there were no changes in leaf cytokinin levels. Images Figure 3 Figure 4 PMID:16667366

Smit, Barbara A.; Neuman, Dawn S.; Stachowiak, Matthew L.

1990-01-01

498

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

PubMed

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

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

2014-04-01

499

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

PubMed

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

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

2014-07-01

500

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, Hervé

2002-09-01