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1

Multisite phosphorylation of spinach leaf sucrose-phosphate synthase  

SciTech Connect

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

Huber, J.L.; Huber, S.C. (North Carolina State Univ., Raleigh (USA))

1990-05-01

2

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

SciTech Connect

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

Huber, J.L. (North Carolina State Univ., Raleigh (United States)); Huber, S.C. (Dept. of Agriculture, Raleigh, NC (United States) North Carolina State Univ., Raleigh (United States)); Hite, D.R.C.; Outlaw, W.H. Jr. (Florida State Univ., Tallahassee (United States))

1991-01-01

3

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

SciTech Connect

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

Huber, J.L.A.; Huber, S.C. (North Carolina State Univ., Raleigh (USA))

1989-04-01

4

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

Microsoft Academic Search

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

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

2007-01-01

5

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

E-print Network

Environmental stress Á Sucrose, starch, and cellulose metabolism Á Transgenic cotton C. H. Haigler (&) Á B-type and transgenic null controls. Leaves of transgenic SPS over-expressing lines showed higher sucrose:starch ra- tio and partitioning of 14 C to sucrose in preference to starch. In two growth chamber experiments with cool nights

Strauss, Richard E.

6

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

7

Spinach  

Microsoft Academic Search

Spinach is arguably the #1 or # 2 most nutritious vegetable (broccoli being the other) that is consumed in the United States.\\u000a It is very versatile since it is commonly used as a salad, a cooked vegetable or as a component of many other cooked meat\\u000a and vegetable dishes. The recent development of baby leaf spinach coupled with an upswing

Teddy E. Morelock; James C. Correll

8

Cloning and expression analysis of sucrose-phosphate synthase from sugar beet ( Beta vulgaris L.)  

Microsoft Academic Search

A cDNA clone encoding a sucrose-phosphate synthase from sugar beet (BvSPS 1) has been isolated by screening a tap root-specific cDNA library using a heterologous SPS cDNA from spinach. The 3635 by sugar beet cDNA codes for a 1045 amino acid polypeptide with a predicted molecular mass of 118 kDa. The deduced amino acid sequence of sugar beet SPS shows

Holger Hesse; Uwe Sonnewald; Lothar Willmitzer

1995-01-01

9

Elevated sucrose-phosphate synthase activity in transgenic tobacco sustains photosynthesis in older leaves and alters development  

Microsoft Academic Search

Constitutive over-expression of a maize sucrose- phosphate synthase (SPS) gene in tobacco (Nicotiana tabacum) had major effects on leaf carbo- hydrate budgets with consequences for whole plant development. Transgenic tobacco plants flowered earlier and had greater flower numbers than wild-type plants. These changes were not linked to modified source leaf carbon assimilation or carbon export, although sucrose to starch ratios

Charles J. Baxter; Christine H. Foyer; Janice Turner; Stephen A. Rolfe; W. Paul Quick

2003-01-01

10

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

PubMed

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

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

2014-10-01

11

Cloning and molecular analysis of cDNAs encoding three sucrose phosphate synthase isoforms from a citrus fruit (Citrus unshiu Marc.).  

PubMed

Three partial cDNA clones (pSPS1, pSPS2 and pSPS3) encoding sucrose phosphate synthases (SPS) were isolated by Reverse Transcription (RT)-PCR using first-strand cDNA prepared from the leaf or fruit of citrus (Citrus unshiu Marc.). The nucleotide and deduced amino acid sequences of the three clones showed significant similarities to SPS previously isolated in other plants. A full-length, cDNA clone, CitSPS1, was isolated from a fruit (juice sacs and pulp segment) cDNA library using one (pSPS1) of the three partial clones as a probe. The 3539-bp CitSPS1 clone coded for a 1057-amino acid polypeptide with a predicted molecular mass of 117.8 kDa. The amino acid sequence deduced from the CitSPS1 clone showed homology with SPS from maize (55.8% identity) and spinach (74.0% identity). Genomic Southern blot analysis suggested that CitSPS1 clone represents a lowcopy-number gene. RNA blot analysis of leaf, flower and fruit showed that CitSPS1 and pSPS2 were expressed in all organs. However, the levels of expression of CitSPS1 in young leaves, flowers and immature fruits were low, but high in mature leaves, and fruit. pSPS2 transcripts were barely detectable in young leaves and immature fruits, low in mature leaves, and high in flowers and mature fruits. pSPS3 transcripts were only detected in young and in mature leaves. PMID:8842155

Komatsu, A; Takanokura, Y; Omura, M; Akihama, T

1996-09-13

12

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

E-print Network

Characterization of interactions between Escherichia coli O157:H7 with epiphytic bacteria in vitro Escherichia coli O157:H7 Antagonism This study characterized the types of interactions between Escherichia for their ability to inhibit or to enhance the growth of E. coli O157:H7 in vitro and on spinach leaf surfaces

Falkinham, Joseph

13

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

PubMed Central

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

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

1972-01-01

14

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

PubMed

Spinach leaf NADH:nitrate reductase (NR) responds to light/dark signals and photosynthetic activity in part as a result of rapid regulation by reversible protein phosphorylation. We have identified the major regulatory phosphorylation site as Ser-543, which is located in the hinge 1 region connecting the cytochrome b domain with the molybdenum-pterin cofactor binding domain of NR, using recombinant NR fragments containing or lacking the phosphorylation site sequence. Studies with NR partial reactions indicated that the block in electron flow caused by phosphorylation also could be localized to the hinge 1 region. A synthetic peptide (NR6) based on the phosphorylation site sequence was phosphorylated readily by NR kinase (NRk) in vitro. NR6 kinase activity tracked the ATP-dependent inactivation of NR during several chromatographic steps and completely inhibited inactivation/phosphorylation of native NR in vitro. Two forms of NRk were resolved by using anion exchange chromatography. Studies with synthetic peptide analogs indicated that both forms of NRk had similar specificity determinants, requiring a basic residue at P-3 (i.e., three amino acids N-terminal to the phosphorylated serine) and a hydrophobic residue at P-5. Both forms are strictly calcium dependent but belong to distinct families of protein kinases because they are distinct immunochemically. PMID:8721752

Bachmann, M; Shiraishi, N; Campbell, W H; Yoo, B C; Harmon, A C; Huber, S C

1996-03-01

15

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

16

Cloning and molecular analysis of cDNAs encoding three sucrose phosphate synthase isoforms from a citrus fruit ( Citrus unshiu Marc.)  

Microsoft Academic Search

Three partial cDNA clones (pSPS1, pSPS2 and pSPS3) encoding sucrose phosphate synthases (SPS) were isolated by Reverse Transcription (RT)-PCR using first-strand cDNA prepared from the leaf or fruit of citrus (Citrus unshiu Marc.). The nucleotide and deduced amino acid sequences of the three clones showed significant similarities to SPS previously isolated in other plants. A full-length, cDNA clone, CitSPS1, was

A. Komatsu; Y. Takanokura; T. Akihama; M. Omura

1996-01-01

17

The identification and characterisation of alleles of sucrose phosphate synthase gene family III in sugarcane  

Microsoft Academic Search

Little is known about the extent of allelic diversity of genes in the complex polyploid, sugarcane. Using sucrose phosphate synthase (SPS) Gene (SPS) Family III as an example, we have amplified and sequenced a 400nt region from this gene from two sugarcane lines that are parents of a mapping population. Ten single nucleotide polymorphisms (SNPs) were identified within the 400nt

C. L. McIntyre; M. Jackson; G. M. Cordeiro; O. Amouyal; S. Hermann; K. S. Aitken; F. Eliott; R. J. Henry; R. E. Casu; G. D. Bonnett

2006-01-01

18

Sucrose-Phosphate Synthase, Sucrose Synthase, and Invertase in Sugar Beet Leaves  

Microsoft Academic Search

The activity of sucrose-phosphate synthase (SPS) in sugar beet (Beta vulgaris L.) leaves was shown to exceed considerably the synthesizing activity of sucrose synthase (SS). The rise in SPS activity was related to the daylight period; i.e., it was associated with the rate of photosynthesis. The highest SPS activity was characteristic of fully expanded source leaves. In young developing leaves

O. A. Pavlinova; E. N. Balakhontsev; M. F. Prasolova; M. V. Turkina

2002-01-01

19

Sucrose-phosphate synthase steady-state mRNA increases in ripening kiwifruit  

Microsoft Academic Search

Early during fruit ripening in kiwifruit (Actinidia deliciosa var. deliciosa [A. Chev.], C.F. Liang and A.R. Ferguson cv. Hayward), starch is broken down to sucrose and hexose sugars. Concomitantly, sucrose-phosphate synthase (SPS, EC 2.3.1.14) activity measured with saturating substrate increased, suggesting that SPS is induced in response to a higher requirement for sucrose synthesis [29]. A 2584 bp long partial

Georg Langenkmper; Ronnie McHale; Richard C. Gardner; Elspeth MacRae

1998-01-01

20

The proteome map of spinach leaf peroxisomes indicates partial compartmentalization of phylloquinone (vitamin K1) biosynthesis in plant peroxisomes.  

PubMed

Leaf peroxisomes are fragile, low-abundance plant cell organelles that are difficult to isolate from one of the few plant species whose nuclear genome has been sequenced. Leaf peroxisomes were enriched at high purity from spinach (Spinacia oleracea) and approximately 100 protein spots identified from 2-dimensional gels by a combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and de novo sequencing. In addition to the predominant enzymes involved in photorespiration and detoxification, several minor enzymes were detected, underscoring the high sensitivity of the protein identification. The tryptic peptides of three unknown proteins shared high sequence similarity with Arabidopsis proteins that carry putative peroxisomal targeting signals type 1 or 2 (PTS1/2). The apparent Arabidopsis orthologues are a short-chain alcohol dehydrogenase (SDRa/IBR1, At4g05530, SRL>) and two enoyl-CoA hydratases/isomerases (ECHIa, At4g16210, SKL>; NS/ECHId, At1g60550, RLx(5)HL). The peroxisomal localization of the three proteins was confirmed in vivo by tagging with enhanced yellow fluorescent protein (EYFP), and the targeting signals were identified. The single Arabidopsis isoform of naphthoate synthase (NS) is orthologous to MenB from cyanobacteria, which catalyses an essential reaction in phylloquinone biosynthesis, a pathway previously assumed to be entirely compartmentalized in plastids in higher plants. In an extension of a previous study, the present in vivo targeting data furthermore demonstrate that the enzyme upstream of NS, chloroplastic acyl-CoA activating enzyme isoform 14 (AAE14, SSL>), is dually targeted to both plastids and peroxisomes. This proteomic study, extended by in vivo subcellular localization analyses, indicates a novel function for plant peroxisomes in phylloquinone biosynthesis. PMID:20150517

Babujee, Lavanya; Wurtz, Virginie; Ma, Changle; Lueder, Franziska; Soni, Pradeep; van Dorsselaer, Alain; Reumann, Sigrun

2010-03-01

21

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

22

Spinach or amaranth contains highest residue of metalaxyl, fluazifop-P-butyl, chlorpyrifos, and lambda-cyhalothrin on six leaf vegetables upon open field application.  

PubMed

To select representative leaf vegetables which may contain the highest residue, field experiments of metalaxyl, fluazifop-P-butyl, chlorpyrifos, and lambda-cyhalothrin on six crops including pakchoi, rape, crown daisy, amaranth, spinach, and lettuce were designed and conducted. In this study, a high-performance liquid chromatograph and electrospray ionization tandem mass spectrometer with multiple reaction monitoring was used to simultaneously determine metalaxyl and fluazifop-P-butyl residue in various samples, and a gas chromatograph with electron capture detector was used to detect chlorpyrifos and lambda-cyhalothrin. The limits of quantification (LOQ) of metalaxyl, fluazifop-P-butyl, chlorpyrifos, and lambda-cyhalothrin were in the range of 0.001-0.01 mg kg(-1) for all samples, and the average recoveries of all pesticides ranged from 67.6 to 119.1% at spiked levels of 0.01-0.1 mg kg(-1). In supervised field trials, the half-lives of metalaxyl, fluazifop-P-butyl, chlorpyrifos, and lambda-cyhalothrin were in the range of 1.11-3.79 days, 1.11-2.27 days, 1.13-5.17 days, and 1.77-6.24 days. It was also found that all pesticide residues in spinach and/or amaranth were higher than others after application. It is recommended that spinach or amaranth can be selected as a representative crop of leaf vegetables in studying systemic fungicide, insecticides, and herbicides with similarity as metalaxyl, fluazifop-P-butyl, chlorpyrifos, and lambda-cyhalothrin. PMID:23387923

Fan, Sufang; Zhang, Fengzu; Deng, Kailin; Yu, Chuanshan; Liu, Shaowen; Zhao, Pengyue; Pan, Canping

2013-03-01

23

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

SciTech Connect

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

Huber, S.C.; Huber, J.L. (North Carolina State Univ., Raleigh (USA))

1990-05-01

24

Delineating the structural, functional and evolutionary relationships of sucrose phosphate synthase gene family II in wheat and related grasses  

Microsoft Academic Search

BackgroundSucrose phosphate synthase (SPS) is an important component of the plant sucrose biosynthesis pathway. In the monocotyledonous\\u000a Poaceae, five SPS genes have been identified. Here we present a detailed analysis of the wheat SPSII family in wheat. A set of homoeologue-specific primers was developed in order to permit both the detection of sequence variation,\\u000a and the dissection of the individual

Shailendra Sharma; Nese Sreenivasulu; Vokkaliga Thammegowda Harshavardhan; Christiane Seiler; Shiveta Sharma; Zaynali Nezhad Khalil; Eduard Akhunov; Sunish Kumar Sehgal; Marion S Rder

2010-01-01

25

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

26

RoleofSucrose Phosphate Synthase inSucrose Biosynthesis inRipening BananasandIts Relationship totheRespiratory Climacteric  

Microsoft Academic Search

During ripening ofbananas(Musa spp.(AAAgroup, Cavendish subgroup)), there isamassive conversion ofstarch tosucrose. Alsoduring ripening there isa rise inrespiration knownasthe respiratory climacteric. Inthisstudychanges incarbohydrate content, activities ofstarch andsucrosemetabolizing enzymes, andrespiration weremeasured toassesstheir potential interre- lationships. Sucrose phosphate synthase activity increased dra- matically during thefirst 4daysafter initiation ofripening by ethylene treatment. Starch concentration decreased andsucrose concentration increased during this timeperiod. Developmental changes insucrosephosphate

Natalie L. Hubbard; D. MasonPharr; C. Huber

27

Effect of Photoperiod on Photosynthate Partitioning and Diurnal Rhythms in Sucrose Phosphate Synthase Activity in Leaves of Soybean (Glycine max L. [Merr.]) and Tobacco (Nicotiana tabacum L.).  

PubMed

Studies were conducted to identify the existence of diurnal rhythms in sucrose phosphate synthase (SPS) activity in leaves of three soybean (Glycine max L. [Merr.]) and two tobacco (Nicotiana tabacum L.) cultivars and the effect of photoperiod (15 versus 7 hours) on carbohydrate partitioning and the rhythm in enzyme activity. Acclimation of all the genotypes tested to a short day (7 hours) photoperiod resulted in increased rates of starch accumulation, whereas rates of translocation, foliar sucrose concentrations, and activities of SPS were decreased relative to plants acclimated to long days (15 hours). Under the long day photoperiod, two of the three soybean cultivars (;Ransom' and ;Jupiter') and one of the two tobacco cultivars (;22NF') studied exhibited a significant diurnal rhythm in SPS activity. With the soybean cultivars, acclimation to short days reduced the activity of SPS (leaf fresh weight basis) and tended to dampen the amplitude of the rhythm. With the tobacco cultivars, photoperiod affected the shape of the SPS-activity rhythm. The mean values for SPS activity (calculated from observations made during the light period) were correlated positively with translocation rates and were correlated negatively with starch accumulation rates. Overall, the results support the postulate that SPS activity is closely associated with starch/sucrose levels in leaves, and that acclimation to changes in photoperiod may be associated with changes in the activity of SPS. PMID:16663738

Huber, S C; Rufty, T W; Kerr, P S

1984-08-01

28

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

SciTech Connect

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

Pollard, M.; Ohlrogge, J.

1999-12-01

29

Conversion of l-Sorbosone to l-Ascorbic Acid by a NADP-Dependent Dehydrogenase in Bean and Spinach Leaf 1  

PubMed Central

An NADP-dependent dehydrogenase catalyzing the conversion of l-sorbosone to l-ascorbic acid has been isolated from Phaseolus vulgaris L. and Spinacia oleracea L. and partially purified. It is stable at ?20C for up to 8 months. Molecular masses, as determined by gel filtration, were 21 and 29 kilodaltons for bean and spinach enzymes, respectively. Km for sorbosone were 12 2 and 18 2 millimolar and for NADP+, 0.14 0.05 and 1.2 0.5 millimolar, for bean and spinach, respectively. Lycorine, a purported inhibitor of l-ascorbic acid biosynthesis, had no effect on the reaction. PMID:16667860

Loewus, Mary W.; Bedgar, Diana L.; Saito, Kazumi; Loewus, Frank A.

1990-01-01

30

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

SciTech Connect

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

Loewus, M.W.; Bedgar, D.L.; Saito, Kazumi; Loewus, F.A. (Washington State Univ., Pullman (USA))

1990-11-01

31

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

32

Sucrose-phosphate synthase is regulated via metabolites and protein phosphorylation in potato tubers, in a manner analogous to the enzyme in leaves  

Microsoft Academic Search

(i) Sucrose-phosphate synthase (SPS) was purified 40-fold from stored potato (Solanum tuberosum L.) tubers to a final specific activity of 3370 nkat(mg protein)-1 via batch elution from diethylaminoethyl (DEAE)-sephacel, polyethylene glycol (PEG) precipitation and Mono Q anion-exchange chromatography. (ii) Immunoblotting revealed a major and a minor band with molecular weights of 124.8 kDa and 133.5 kDa, respectively. Both bands were

Ralph Reimholz; Peter Geigenberger; Mark Stitt

1994-01-01

33

Photoreduction of sulfur dioxide by spinach leaves and isolated spinach chloroplasts  

Microsoft Academic Search

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

J. E. Silvius; C. H. Baer; S. Dodrill; H. Patrick

1976-01-01

34

Texas Crop Profile: Spinach  

E-print Network

affect aphid numbers in spinach. Synthetic pyrethroid use can trigger an aphid buildup. 2 Table 1: Aphid Chemical Controls. Pesticide % Acres Treated Type of Appl. Typical Rates Timing # of Appl. Imidacloprid 60 air 3.7 oz. Apply when one to two aphids... stage of a fly. They are very similar to the seed corn maggot. Crown maggots are attracted to seedling crowns covered with soil splashed by rains and to decaying spinach residue left from the first cutting. This habitat attraction plus the short life...

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

2000-04-12

35

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

PubMed

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

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

2009-05-13

36

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

PubMed

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

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

2014-08-01

37

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

Microsoft Academic Search

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

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

2010-01-01

38

Light Modulation and Localization of Sucrose Phosphate Synthase Activity between Mesophyll Cells and Bundle Sheath Cells in C4 Species 1  

PubMed Central

Experiments were conducted with several Panicum species (representing the different C4 subtypes) to examine the light modulation of sucrose phosphate synthase (SPS) activity and the effect of illumination on the distribution of SPS activity between mesophyll cells (MC) and bundle sheath cells (BSC). Activity of SPS in the light decreased in the order: C4 > C3-C4 intermediate > C3. In illuminated leaves, SPS activities were similar among the three C4 subtypes, but SPS activity was higher for NAD-malic enzyme (NAD-ME) species with centripetal chloroplasts in BSC (NAD-ME(P) species) than for NAD-ME species with centrifugal chloroplasts in BSC (NAD-ME(F) species). Transfer of plants into darkness for 30 minutes resulted in decreased SPS activity for all species tested except Panicum bisulcatum (C3 species) and Panicum virgatum (NAD-ME(P) species) which showed little or no change. All C4 subtypes had some SPS activity both in MC and BSC. In the light, SPS activity was mainly in the MC for NADP-ME, NAD-ME(F) and phosphoenolpyruvate carboxykinase species, while it was mainly in the BSC for NAD-ME(P) species. In the dark, for all C4 subtypes, SPS activity in the MC was decreased to a greater extent than that in the BSC. It is intriguing that NAD-ME(F) and NAD-ME(P) species differed in the activity and distribution of SPS activity between MC and BSC, although they are otherwise identical in the photosynthetic carbon assimilation pathway. Diurnal changes in SPS activity in the MC and BSC were also examined in maize leaves. SPS activity in the MC in maize leaves was high and relatively constant throughout the middle of the light period, dropped rapidly after sunset and increased again prior to the light period. On the other hand, SPS activity in the BSC was lower and changed more coincidently with light intensity than that in the MC. The results suggested that light activation of SPS activity located in the BSC may require higher irradiance for saturation than the SPS in the MC. We conclude that SPS may function in both MC and BSC for sucrose synthesis in the light, particularly at high light intensity, while in the dark, the major function may be in the BSC during starch degradation. PMID:16665568

Ohsugi, Ryu; Huber, Steven C.

1987-01-01

39

[Determination of uranium in spinach].  

PubMed

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

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

2013-01-01

40

Leaf development in Ricinus communis during drought stress: dynamics of growth processes, of cellular structure and of sink-source transition  

Microsoft Academic Search

Dicot leaf growth is characterized by partly transient phyll, protein, sucrose phosphate synthase, sucrose tip-to-base gradients of growth processes, structure synthase. and function. These gradients develop dynamically and interact with dynamically developing stress conditions like drought. In Ricinus communis plants growing Introduction under well-watered and drought conditions growth Growing tissues are characterized by the simultaneous rates peaked during the late

U. Schurr; U. Heckenberger; K. Herdel; A. Walter; R. Feil

2000-01-01

41

Direct organogenesis in Indian spinach  

Microsoft Academic Search

An efficient and reproducible protocol for plant regeneration through in vitro culture of Indian spinach (Beta palonga) is reported. Shoot buds were obtained both from blade petiole transition zones and midribs of fully expanded leaves. Murashige and Skoog's basal medium supplemented with naphthaleneacetic acid and benzyladenine (each at 1 mg l-1) resulted in high frequency shoot organogenesis. Histological studies showed

Srijeet Kumar Mitra; Kalyan Kumar Mukherjee

2001-01-01

42

Subcellular localization of acyl carrier protein in leaf protoplasts of Spinacia oleracea.  

PubMed Central

This communication demonstrates that all de novo fatty acid biosynthesis in spinach leaf cells requires acyl carrier protein (ACP) and occurs specifically in the chloroplasts. Antibodies raised to purified spinach ACP inhibited at least 98% of malonyl CoA-dependent fatty acid synthesis by spinach leaf homogenates. Therefore, the presence of ACP in a compartment of the spinach leaf cell would serve as a marker for de novo fatty acid biosynthesis. A radioimmunoassay capable of detecting 10(15) mol (10(-11) g) of spinach ACP was developed to measure the levels of ACP in leaf cell components isolated by sucrose gradient centrifugation of a gentle lysate of spinach leaf protoplasts. All of the ACP of the leaf cell could be attributed to the chloroplast. Less than 1% of the ACP associated with chloroplasts resulted from binding of free ACP to chloroplasts. Of interest, ACP from Escherichia coli, soybean, and sunflower showed only partial crossreactivity with spinach ACP by the radioimmunoassay. These results strongly suggest that, in the leaf cell, chloroplasts are the sole site for the de novo synthesis of C16 and C18 fatty acids. These fatty acids are then transported into the cytoplasm for further modification and are either inserted into extrachloroplastic membrane lipids or returned to the chloroplast for insertion into lamellar membrane lipids. PMID:286305

Ohlrogge, J B; Kuhn, D N; Stumpf, P K

1979-01-01

43

Choline oxidation by intact chloroplasts isolated directly from spinach leaves  

SciTech Connect

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

Weigel, P.; Hanson, A.D.

1986-04-01

44

Direct Spectrophotometric Measurement of Photosystem I and Photosystem II Activities of Photosynthetic Membrane Preparations from Cyanophora paradoxa, Phormidium laminosum, and Spinach.  

PubMed

Vesicles prepared with the French press from membranes of cyanelles of Cyanophora paradoxa retain O(2) evolution activity with rates up to 500 micromoles 2,6-dichlorophenolindophenol reduced per hour per milligram chlorophyll. This activity is immediately lost when the vesicles are transferred from the sucrose-phosphate-citrate preparation buffer into dilute phosphate buffer. Similar preparations from Phormidium laminosum, a thermophilic cyanobacterium retain activity under such conditions. Photosystem I activities of both cyanobacterial vesicle preparations were determined by direct spectrophotometric measurement of N,N,N',N'-tetramethyl-p-phenylenediamine photooxidation in the presence of anthraquinone-2-sulfonate. The rates so determined were compared with rates of O(2) taken up in the presence of methyl viologen or anthraquinone-2-sulfonate as electron acceptors. The predicted stoichiometry of two was observed for moles of N,N,N',N'-tetramethyl-p-phenylenediamine oxidized per mole of oxygen taken up. Anthraquinone-2-sulfonate was the better electron acceptor, and maximal rates of 943 micromoles per hour per milligram chlorophyll for O(2) uptake were observed for Phormidium laminosum preparations in the presence of superoxide dismutase. For purposes of comparison, spinach chloroplasts were assayed for similar activities. All preparations were readily assayed for photosystem I activity by the direct spectrophotometric method, which has advantages of simplicity and freedom from errors introduced by photoxidation of other substrates by photosystem I when O(2) uptake is measured. PMID:16662512

Vernon, L P; Cardon, S

1982-08-01

45

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

PubMed Central

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

Kar, Rup K.; Choudhuri, Monojit A.

1986-01-01

46

Essential oils reduce Escherichia coli O157:H7 and Salmonella on spinach leaves.  

PubMed

The efficacy of cinnamaldehyde and Sporan for reducing Escherichia coli O157:H7 and Salmonella on spinach leaves was investigated. Spinach leaves were inoculated with a five-strain cocktail of Salmonella or E. coli O157:H7, air dried for ca. 30 min, and then immersed in a treatment solution containing 5 ppm of free chlorine, cinnamaldehyde, or Sporan (800 and 1,000 ppm) alone or in combination with 200 ppm of acetic acid (20%) for 1 min or with water (control). After spin drying, treated leaves were analyzed periodically during 14 days of storage at 4C for Salmonella, E. coli O157:H7, total coliforms, mesophilic and psychrotrophic bacteria, and yeasts and molds. Treatment effects on color and texture of leaves also were determined. Sporan alone (1,000S), Sporan plus acetic acid (1,000SV), and cinnamaldehyde-Tween (800T) reduced E. coli O157:H7 by more than 3 log CFU/g (P < 0.05), and 1,000SV treatment reduced Salmonella by 2.5 log CFU/g on day 0. E. coli O157:H7 and Salmonella populations on treated spinach leaves declined during storage at 4C. The 1,000SV treatment was superior to chlorine and other treatments for reducing E. coli O157:H7 during storage. Saprophytic microbiota on spinach leaves increased during storage at 4C but remained lower on leaves treated with Sporan (800S) and Sporan plus acetic acid (1,000SV) than on control leaves. The color and texture of Sporan-treated leaves were not significantly different from those of the control leaves after 14 days. Sporan plus acetic acid (1,000SV) reduced E. coli O157:H7 and Salmonella on baby spinach leaves without adverse effects on leaf color and texture. PMID:22410222

Yossa, Nadine; Patel, Jitendra; Millner, Patricia; Lo, Y Martin

2012-03-01

47

Lithium Decreases Cold-Induced Microtubule Depolymerization in Mesophyll Cells of Spinach 1  

PubMed Central

Freezing, dehydration, and supercooling cause microtubules in mesophyll cells of spinach (Spinacia oleracea L. cv Bloomsdale) to depolymerize (ME Bartolo, JV Carter [1991] Plant Physiol 97: 175-181). The objective of this study was to gain insight into the question of whether microtubules depolymerize as a direct response to environmental stresses or as an indirect response to cellular changes that accompany the stresses. Leaf sections of spinach were treated with Li+ before and during exposure to low temperature. Treatment with Li+ decreased the amount of microtubule depolymerization in cells subjected to low temperature, relative to a nontreated control, raising the possibility that the microtubules in these cells may not be inherently cold labile. Rather, microtubule depolymerization may be in response to cold-induced changes in concentration of cytoplasmic components. PMID:16669100

Bartolo, Michael E.; Carter, John V.

1992-01-01

48

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 28C 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

49

Microtubules in Mesophyll Cells of Nonacclimated and Cold-Acclimated Spinach 1  

PubMed Central

Responses of cortical microtubules in spinach (Spinacia oleracea L. cv Bloomsdale) mesophyll cells to freezing, thawing, supercooling, and dehydration were assessed. Microtubules were visualized using a modified procedure for indirect immunofluorescence microscopy. Leaf sections of nonacclimated and cold-acclimated spinach were slowly frozen to various temperatures, fixed while frozen, and microtubules immunolabelled. Both nonacclimated and cold-acclimated cells exhibited nearly complete microtubule depolymerization after ice formation. After 1 hour thawing at 23C, microtubules in both nonacclimated and cold-acclimated cells repolymerized. With time, however, microtubules in nonacclimated cells again depolymerized. Since microtubules in cells of leaf tissue frozen slowly are subjected to dehydration as well as subzero temperatures, these stresses were applied separately and their effects on microtubules noted. Supercooling induced microtubule depolymerization in both nonacclimated and cold-acclimated cells, but to a smaller extent than did freezing. Exposing leaf sections to solutions of sorbitol (a cell wall-penetrating osmoticum) or polyethylene glycol 10,000 (a nonpenetrating osmoticum) at room temperature caused microtubule depolymerization. The effects of low temperature and dehydration are roughly additive in producing the observed microtubule responses during freezing. Only small differences in microtubule stability were resolved between nonacclimated and cold-acclimated cells. ImagesFigure 2 PMID:16668366

Bartolo, Michael E.; Carter, John V.

1991-01-01

50

Structural Similarities between Spinach Chloroplast and Cytosolic Class I Fructose 1,6-Bisphosphate Aldolases 1  

PubMed Central

Immunochemical studies using polyclonal antisera prepared individually against highly purified cytosolic and chloroplast spinach leaf (Spinacia oleracea) fructose bisphosphate aldolases showed significant cross reaction between both forms of spinach aldolase and their heterologous antisera. The individual cross reactions were estimated to be approximately 50% in both cases under conditions of antibody saturation using a highly sensitive enzyme-linked immunosorbent assay. In contrast, the class I procaryotic aldolase from Mycobacterium smegmatis and the class II aldolase from yeast (Saccharomyces cerevisiae) did not cross-react with either type of antiserum. The 29 residue long amino-terminal amino acid sequences of the procaryotic M. smegmatis and the spinach chloroplast aldolases were determined. Comparisons of these sequences with those of other aldolases showed that the amino-terminal primary structure of the chloroplast aldolase is much more similar to the amino-terminal structures of class I cytosolic eucaryotic aldolases than it is to the corresponding region of the M. smegmatis enzyme, especially in that region which forms the first beta sheet in the secondary structure of the eucaryotic aldolases. Moreover, results of a systematic comparison of the amino acid compositions of a number of diverse eucaryotic and procaryotic fructose bisphosphate aldolases further suggest that the chloroplast aldolase belongs to the eucaryotic rather than the procaryotic family of class I aldolases. Images Figure 1 Figure 2 PMID:16667191

Marsh, James J.; Wilson, Kenneth J.; Lebherz, Herbert G.

1989-01-01

51

Effect of Microtubule Stabilization on the Freezing Tolerance of Mesophyll Cells of Spinach 1  

PubMed Central

Freezing, dehydration, and supercooling cause microtubules in mesophyll cells of spinach (Spinacia oleracea L. cv Bloomsdale) to depolymerize (ME Bartolo, JV Carter, Plant Physiol [1991] 97: 175-181). The objective of this study was to determine whether the LT50 (lethal temperature: the freezing temperature at which 50% of the tissue is killed) of spinach leaf tissue can be changed by diminishing the extent of microtubule depolymerization in response to freezing. Also examined was how tolerance to the components of extracellular freezing, low temperature and dehydration, is affected by microtubule stabilization. Leaf sections of nonacclimated and cold-acclimated spinach were treated with 20 micromolar taxol, a microtubule-stabilizing compound, prior to freezing, supercooling, or dehydration. Taxol stabilized microtubules against depolymerization in cells subjected to these stresses. When pretreated with taxol both nonacclimated and cold-acclimated cells exhibited increased injury during freezing and dehydration. In contrast, supercooling did not injure cells with taxol-stabilized microtubules. Electrolyte leakage, visual appearance of the cells, or a microtubule repolymerization assay were used to assess injury. As leaves were cold-acclimated beyond the normal period of 2 weeks taxol had less of an effect on cell survival during freezing. In leaves acclimated for up to 2 weeks, stabilizing microtubules with taxol resulted in death at a higher freezing temperature. At certain stages of cold acclimation, it appears that if microtubule depolymerization does not occur during a freeze-thaw cycle the plant cell will be killed at a higher temperature than if microtubule depolymerization proceeds normally. An alternative explanation of these results is that taxol may generate abnormal microtubules, and connections between microtubules and the plasma membrane, such that normal cellular responses to freeze-induced dehydration and subsequent rehydration are blocked, with resultant enhanced freezing injury. ImagesFigure 1Figure 2Figure 6 PMID:16668367

Bartolo, Michael E.; Carter, John V.

1991-01-01

52

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

PubMed

The microbiological safety of fresh produce is of concern for the U.S. food supply. Members of the Lactic Acid Bacteria (LAB) have been reported to antagonize pathogens by competing for nutrients and by secretion of substances with antimicrobial activity, including organic acids, peroxides, and antimicrobial polypeptides. The objectives of this research were to: (i) determine the capacity of a commercial LAB food antimicrobial to inhibit Escherichia coli O157:H7 and Salmonella enterica on spinach leaf surfaces, and (ii) identify antimicrobial substances produced invitro by the LAB comprising the food antimicrobial. Pathogens were inoculated on freshly harvested spinach, followed by application of the LAB antimicrobial. Treated spinach was aerobically incubated up to 12 days at 7C and surviving pathogens enumerated via selective/differential plating. l-Lactic acid and a bacteriocin-like inhibitory substance (BLIS) were detected and quantified from cell-free fermentates obtained from LAB-inoculated liquid microbiological medium. Application of 8.0log10CFU/g LAB produced significant (p<0.05) reductions in E.coli O157:H7 and Salmonella populations on spinach of 1.6 and 1.9log10CFU/g, respectively. It was concluded the LAB antimicrobial inhibited foodborne pathogens on spinach during refrigerated storage, likely the result of the production of metabolites with antimicrobial activity. PMID:24290643

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

2014-04-01

53

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

54

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

55

Growth Conditions To Reduce Oxalic Acid Content of Spinach  

NASA Technical Reports Server (NTRS)

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

Johnson-Rutzke, Corinne

2003-01-01

56

Furoquinoline alkaloids isolated from Balfourodendron riedelianum as photosynthetic inhibitors in spinach chloroplasts.  

PubMed

In the search for natural inhibitors of plant growth, we investigate the mechanism of action of the natural furoquinoline alkaloids isolated from Balfourodendron riedelianum (Rutaceae): evolitrine (1), kokusaginine (2), ?-fagarine (3), skimmianine (4) and maculosidine (5) on the photosynthesis light reactions. Their effect on the electron transport chain on thylakoids was analyzed. Alkaloids 1, 2, 4 and 5 inhibited ATP synthesis, basal, phosphorylating and uncoupled electron transport acting as Hill reaction inhibitors on spinach chloroplasts. Alkaloid 3 was not active. The inhibition and interaction site of alkaloids 1, 2, 4 and 5 on the non-cyclic electron transport chain was studied by polarography and fluorescence of the chlorophyll a (Chl a). The results indicate that the target for 1 was localized on the donor and acceptor side of PS II. In addition alkaloids 2 and 5 affect the PS I electron acceptors on leaf discs. PMID:23416711

Veiga, Thiago Andr Moura; King-Daz, Beatriz; Marques, Anna Sylvia Ferrari; Sampaio, Olivia Moreira; Vieira, Paulo Cezar; da Silva, Maria Ftima das Graas Fernandes; Lotina-Hennsen, Blas

2013-03-01

57

Glycolate Formation in Intact Spinach Chloroplasts 1  

PubMed Central

Photosynthetic 14CO2 fixation and the accumulation of photosynthetic products and the response of each process to both 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU) and ascorbate were investigated in the intact spinach chloroplast. Ascorbate increased the rate of CO2 uptake with an increase in all photosynthetic products, but, proportionally, there was a much larger increase in glycolate formation. CO2 fixation inhibited by DCMU was partially restored on addition of ascorbate. Under conditions not optimal for glycolate formation, such as saturating levels of CO2 and an anaerobic atmosphere, ascorbate in the presence of DCMU restored the formation of all photosynthetic products excluding glycolate. This effect of ascorbate on glycolate synthesis in the presence of DCMU was diminished under conditions which favored glycolate formation. Externally added glycerate 3-phosphate and fructose 1,6-diphosphate depressed the appearance of radioactivity in glycolate. The data are interpreted to indicate that glycolate is produced during photosynthesis as a result of a reaction between a 2-carbon piece derived from a sugar phosphate and an oxidant generated by the photochemical act. The oxidant may be an intermediate of photosystem 2 or a peroxide generated by a mechanism of the Mehler type involving molecular oxygen. PMID:16657328

Plaut, Zvi; Gibbs, Martin

1970-01-01

58

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

PubMed

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

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

2014-03-01

59

[Nondestructive determination of nitrate content in spinach leaves with visible-near infrared high spectra].  

PubMed

The objective of the present research was to study the potential of Vis-NIR (visible-near-infrared) high spectra for nondestructive determination of nitrate content in spinach leaves. Five different nitrogen treatments were carried out to achieve a wide range of nitrate content in spinach leaves. The leaf reflectance was measured between 350 to 2,500 nm with a 1 nm step with a leaf clip by ASD Fieldspec FR spectroradiometer, and the nitrate content was measured by spectrophotometric method (National Standard Method of P. R. China). Statistical models were developed using partial least squares (PLS) and principal component regression (PCR) analysis technique, different mathematical treatments for spectra processing such as smoothing, first and second derivative analysis, baseline correction, multiplicative scatter correction (MSC), and standard normal variate correction (SNV), and different wavelength ranges were compared to determine the best model. The dataset was separated into two parts: one used for calibration (n=43), and the other used for test (n=15). First, the model was calibrated and cross-validated with the calibration dataset, then the model was validated with the test dataset to test its prediction ability. The results showed that smoothing, first derivative and second derivative analysis can improve the prediction obviously, while other spectra pre-processing technique e. g. baseline correction, MSC and SNV technique can improve the prediction little. PCR analysis could get better modeling results than PLS analysis. The best model was obtained with the spectra first processed by smoothing then by first derivative change in the full range (350-2,500 nm). Test of the best PLS model and PCR model with an independent dataset exhibited a good agreement between the predicted and observed values, with the correlation coefficient of 0.94 for PLS model and 0.95 for PCR model, and the prediction RMSE was 128.2 mg x kg(-1) for PLS model and 120.8 mg x kg(-1) for PCR model, respectively. These results indicate that visible-NIR spectra technique is a feasible, nondestructive way to predict the nitrate content in spinach leaves. PMID:19626874

Xue, Li-hong; Yang, Lin-zhang

2009-04-01

60

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

61

USE OF CATALASE FROM SPINACH FOR TESTING AT MOLECULAR LEVEL THE TOXICITY OF SOME IONIC LIQUIDS  

Microsoft Academic Search

SUMMARY The present work tries to evaluate catalase from spinach in order to introduce it into an ecotoxicological test battery. Previous to the determination of the influence of some ionic liquids on spinach catalase activity, the optimization of assay enzyme was performed. Optimum pH for spinach leaves catalase is between 7.5-8. Spinach catalase seems to not be inhibited by its

Ana-Maria Lacr; Laura Pope; Vasile Ostafe

62

Investigation of an Escherichia coli 0157:H7 Outbreak Associated with Dole Pre-Packaged Spinach  

E-print Network

Attachment 11 CDC Addendum Report, "Irrigation Water Issues Potentially Related to 2006 E. coli 0157:H7 in Spinach Outbreak" #12;Irrigation Water Issues Potentially Related to 2006 E. coli 0157:H7 in Spinach............................................................................................................................. 11 Abstract In September, 2006, E. coli 0157:H7 infections associated with fresh spinach affected

63

Trace elements in spinach ( Spinacia oleracea ) cultivated in soil fortified with graded levels of iron  

Microsoft Academic Search

Trace elements in two varieties of spinach cultivated in soil with different levels of added iron were determined. Addition of iron to soil decreased potassium, sodium and magnesium contents in spinach markedly (pp>0.05). Differential behaviour of spinach varieties was found in the zinc, manganese and sodium contents.

N. S. Reddy; T. N. Khan; V. G. Malewar; K. B. Dudde

1995-01-01

64

Ion Channel Permeable for Divalent and Monovalent Cations in Native Spinach Thylakoid Membranes  

E-print Network

Ion Channel Permeable for Divalent and Monovalent Cations in Native Spinach Thylakoid Membranes I thylakoids of spinach (Spinacea oleracea). This channel was per- meable for K+ as well as for Mg2+ and Ca2 permeability of intact spinach thylakoids can be ex- plained on the single channel level by the data presented

Schönknecht, Gerald

65

A new endornavirus species infecting Malabar spinach (Basella alba L.).  

PubMed

A putative new endornavirus was isolated from Malabar spinach (Basella alba). The viral dsRNA consisted of 14,027 nt with a single ORF that coded for a polyprotein of 4,508 aa. The genome organization was similar to that of four other endornaviruses. Conserved domains for helicase-1, capsular synthase, UDP-glucose-glycosyltransferase (UGT), and RdRp were detected. Infected plants were phenotypically undistinguishable from healthy ones. The name Basella alba endornavirus is proposed for the virus isolated from Malabar spinach. PMID:24122112

Okada, Ryo; Kiyota, Eri; Moriyama, Hiromitsu; Toshiyuki, Fukuhara; Valverde, Rodrigo A

2014-04-01

66

Heterogeneous photosystem 2 activity in isolated spinach chloroplasts  

Microsoft Academic Search

A study was made of the fluorescence induction curves from gently-broken spinach chloroplasts inhibited with DCMU. It was found that there were four kinetically different phases associated with such curves of which only the fastest did not appear to follow exponential kinetics. A comparison of the effects of various concentrations of DCMU on the rate of oxygen evolution and on

John Sinclair; Sandra M. Spence

1990-01-01

67

Sulfur dioxide inhibition of photosynthesis in isolated spinach chloroplasts  

Microsoft Academic Search

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

J. E. Silvius; M. Ingle; C. H. Baer

1975-01-01

68

Rapid isolation of intact chloroplasts from spinach leaves.  

PubMed

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

Joly, David; Carpentier, Robert

2011-01-01

69

Light-dependent modification of Photosystem II in spinach leaves  

Microsoft Academic Search

In dark-adapted spinach leaves approximately one third of the Photosystem II (PS II) reaction centers are impaired in their ability to transfer electrons to Photosystem I. Although these inactive PS II centers are capable of reducing the primary quinone acceptor, QA, oxidation of QA- occurs approximately 1000 times more slowly than at active centers. Previous studies based on dark-adapted leaves

Kevin Oxborough; Ladislav Nedbal; Roger A. Chylla; John Whitmarsh

1996-01-01

70

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 Spinach2fluorophore 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

71

Plug-and-play fluorophores extend the spectral properties of Spinach.  

PubMed

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

Song, Wenjiao; Strack, Rita L; Svensen, Nina; Jaffrey, Samie R

2014-01-29

72

Sizes of Mn-binding sites in spinach thylakoids  

SciTech Connect

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

Takahashi, M.; Asada, K.

1986-12-25

73

Studies of GA sub 53 oxidase from spinach  

SciTech Connect

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

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

1990-05-01

74

Chromium Alters Iron Nutrition and Water Relations of Spinach  

Microsoft Academic Search

Spinach (Spinacea oleracea L. cv. Banarasi), known to be responsive to potentially toxic elements, was investigated for chromium (Cr) effect on iron metabolism and water relations. After 40 days growth in sand culture, a set of plants was supplied with 100 and 400 ?M Cr (potassium dichromate, K2Cr2O7), superimposed over the complete nutrient solution (control). Excess Cr produced visual symptoms

Rajeev Gopal; Aqeel Hasan Rizvi; N. Nautiyal

2009-01-01

75

Inhibitory effects of ozone on isolated spinach chloroplasts  

Microsoft Academic Search

Penetration of ozone into spinach chloroplasts and some of the physiological effects of the oxidant have been studied. Ozone fumigation of class II coupled and uncoupled plastids showed that 9 x 10⁻⁷ moles O reduced the Hill reaction by 36% and 43% respectively though 4.4 x 10⁻⁷ moles produced no reduction in coupled plastids and 41% reduction in uncoupled ones.

C. L. Coulson; R. L. Heath

1972-01-01

76

Polarized fluorescence spectroscopy of oriented isolated spinach Photosystem I particles  

Microsoft Academic Search

The fluorescence anisotropy of Photosystem I (PS I) particles, isolated from spinach chloroplasts and containing approximately\\u000a 200 chlorophyll molecules per reaction center, is investigated at low temperatures. The particles are oriented by squeezing\\u000a in polyacrylamid gels with different macroscopic deformation parameters. Fluorescence anisotropy is measured upon steady state\\u000a excitation with a laser line at 632.8 nm. A formula for the

Atanaska Andreeva; Maya Velitchkova

2000-01-01

77

Oxidative Stress Induced by Lead in Chloroplast of Spinach  

Microsoft Academic Search

Seedlings of spinach were grown in Hoaglands medium containing 0, 20, 40, 60, 80, 100?M PbCl2, respectively, for 4weeks. Chloroplasts were assayed for overproduction of reactive oxygen species (ROS) such as superoxide\\u000a radicals (O2\\u000a ??) and hydrogen peoxide (H2O2) and of lipid peroxide (malonyldialdehyde) and for activities of the antioxidant enzymes such as superoxide dismutase, catalase,\\u000a ascorbate peroxidase, and guaiacol

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

2008-01-01

78

Mechanism of lanthanum effect on chlorophyll of spinach.  

PubMed

The mechanism of La(3+) effect on chlorophyll (chl) of spinach in solution culture has been studied. The results show that La(3+) can obviously promote growth, increase chlorophyll contents and photosynthetic rate of spinach. La(3+) may substitute Mg(2+) for chlorophyll formation of spinach when there is no Mg(2+) in solution. La(3+) improves significantly PSII formation and enhances electron transport rate of PSII. By ICP-MS and atom absorption spectroscopy methods, it has been revealed that rare earth elements (REEs) can enter chloroplasts and increase Mg(2+)-chl contents; and REEs bind to chlorophyll and also form REE-chl. REE-chl is about 72% in total chlorophyll with La(3+) treatment and without Mg(2+)in solution. By UV-Vis, FT-IR and extended X-ray absorption fine structure spectroscopy (EXAFS) methods, it has been found that La(3+) coordinates with nitrogen of porphyrin rings with the average La-N bond length of 0.253 nm. PMID:18763076

Hong, Fashui; Wei, Zhenggui; Zhao, Guiwen

2002-04-01

79

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

80

Studies of a New Fusarium Wilt of Spinach in Texas.  

E-print Network

as pathogenic to spinach, as is Fusarium soZuni. Results of these inoculations are shown in Fig. 2, a-h. Pusarium solani, according to Sherbakofl (6), is usually found on rotted potato tubers and on decaying organic matter. It is surprising, therefore... Storage potatoes from Idaho. . 22 March 20, 1925. Sixty per cent of tubers from College Stat~on, Texas. Variety unknown. show very sllght infection around inoculated area, causlng dry rat. Fusarium solani from Irish potatoes storaBe potatoes from Idaho...

Taubenhaus, J. J. (Jacob Joseph)

1926-01-01

81

FRACTIONATION OF SPINACH CHLOROPLASTS BY FLOW SEDIMENTATION-ELECTROPHORESIS  

E-print Network

A separation of spinach chloroplasts in vitro into fractions according to size (volume) and activity (light-dependent shrinkage and NADP reduction) has been achieved by stableflow free boundary sedimentation-electrophoresis. The salient features of this chloroplast study are: (a) separation is achieved within 30 min; (b) only small density gradients are required, thus minimizing osmotic effects; (c) the fractions are collected continuously, with size fractionation being evidenced; and (d) particles are separated into fractions of higher and lower activities as compared with the control population.

Lester Packer; Park S. Nobel; Elizabeth L. Gross; Howard C. Mel

82

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

Microsoft Academic Search

The aim of this study was to investigate the use of water spinach (Ipomoea aquatica Forsk.) with N+ ion-beam implantation for removal of nutrient species from eutrophic water. The mutated water spinach was grown on floating beds, and growth chambers were used to examine the growth of three cultivars of water spinach with ion implantation for 14 days in simulated

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

2007-01-01

83

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

Federal Register 2010, 2011, 2012, 2013

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

2012-05-18

84

A superfolding Spinach2 reveals the dynamic nature of trinucleotide repeat-containing RNA.  

PubMed

Imaging RNA in living cells is a challenging problem in cell biology. One strategy for genetically encoding fluorescent RNAs is to express them as fusions with Spinach, an 'RNA mimic of GFP'. We found that Spinach was dimmer than expected when used to tag constructs in living cells owing to a combination of thermal instability and a propensity for misfolding. Using systematic mutagenesis, we generated Spinach2 that overcomes these issues and can be used to image diverse RNAs. Using Spinach2, we detailed the dynamics of the CGG trinucleotide repeat-containing 'toxic RNA' associated with Fragile X-associated tremor/ataxia syndrome, and show that these RNAs form nuclear foci with unexpected morphological plasticity that is regulated by the cell cycle and by small molecules. Together, these data demonstrate that Spinach2 exhibits improved versatility for fluorescently labeling RNAs in living cells. PMID:24162923

Strack, Rita L; Disney, Matthew D; Jaffrey, Samie R

2013-12-01

85

Leaf Identification  

NSDL National Science Digital Library

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

2008-09-12

86

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

PubMed

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

Brogren, Madelene; Savage, Geoffrey P

2003-01-01

87

Effect of photoperiod on gibberellin biosynthetic enzymes in spinach  

SciTech Connect

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

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

1986-04-01

88

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

89

Choline oxidation by intact spinach chloroplasts. [Spinacia oleracea L  

SciTech Connect

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

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

1988-01-01

90

A superfolding Spinach2 reveals the dynamic nature of trinucleotide repeat RNA  

PubMed Central

Fluorescent imaging of RNA in living cells is a technically challenging problem in cell biology. One strategy for genetically encoding fluorescent RNAs is to express them as fusions with RNA mimics of GFP. These are short aptamer tags that exhibit fluorescence upon binding otherwise nonfluorescent fluorophores that resemble those found in GFP. We find that the brightest of these aptamers, Spinach, often exhibits reduced fluorescence after it is fused to RNAs of interest. We show that a combination of thermal instability and a propensity for misfolding account for the low fluorescence of various Spinach-RNA fusions. Using systematic mutagenesis, we identified nucleotides that account for the poor folding of Spinach, and generated Spinach2, which exhibits markedly improved thermal stability and folding in cells. Furthermore, we show that Spinach2 largely retains its fluorescence when fused to various RNAs. Using Spinach2, we detail the cellular dynamics of the CGG trinucleotide-repeat containing toxic RNA associated with Fragile-X tremor/ataxia syndrome, and show that these RNAs form nuclear foci with unexpected morphological plasticity that is regulated by the cell cycle and by small molecules. Together, these data demonstrate that Spinach2 exhibits improved versatility for fluorescently labeling RNAs in living cells. PMID:24162923

Strack, Rita L.; Disney, Matthew D.; Jaffrey, Samie R.

2013-01-01

91

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

92

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

93

Leaf development.  

PubMed

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

Tsukaya, Hirokazu

2013-01-01

94

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

NASA Astrophysics Data System (ADS)

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

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

1998-01-01

95

Flat Bread Station Zucchini, Ripe Tomato, Feta and Spinach Flat Bread  

E-print Network

Flat Bread Station Zucchini, Ripe Tomato, Feta and Spinach Flat Bread Ricotta Cheese, Romano, Fig Inspired Turkey Burger with Pickled Cucumber, Carrot and Cilantro Slaw Fried Zucchini Slider ­ Roma Tomato

Marsh, David

96

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

E-print Network

CHARACTERIZATION AND IDENTIFICATION OF TWO VIRUS DISEASES OF SPINACH IN SOUTH TEXAS A Thesis by EDWARD BLAIR ADAMS, JR. Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE August 1979 Major Subject: Plant Pathology CHARACTERIZATION AND IDENTIFICATION OF TWO VIRUS DISEASES OF SPINACH IN SOUTH TEXAS A Thesis by EDWARD BLAIR ADAMS, JR. Approved as to style and content by: (Chairman of Committee...

Adams, Edward Blair

2012-06-07

97

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

Microsoft Academic Search

Salt accumulation in spinach (Spinacia oleracea L.) leaves first inhibits photosynthesis by decreasing stomatal and mesophyll conductances to CO2 diffusion and then impairs ribulose- 1,5-bisphosphate carboxylase\\/oxygenase (S. Delfine, A. Alvino, M. Zacchini, F. Loreto (1998) Aust J Plant Physiol 25: 395-402). We measured gas exchange and fluorescence in spinach recovering from salt accumulation. When a 21-d salt accumulation was re-

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

1999-01-01

98

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

99

Effects of Nano-anatase on Spectral Characteristics and Distribution of LHCII on the Thylakoid Membranes of Spinach  

Microsoft Academic Search

In the article, we report that effects of nano-anatase on the spectral characteristics and content of light-harvesting complex\\u000a II (LHCII) on the thylakoid membranes of spinach were investigated. The results showed that nano-anatase treatment could increase\\u000a LHCII content on the thylakoid membranes of spinach and the trimer of LHCII; nano-anatase could enter the spinach chloroplasts\\u000a and bind to PSII. Meanwhile,

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

2007-01-01

100

Uptake of l-Ascorbate by Intact Spinach Chloroplasts  

PubMed Central

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

Beck, Erwin; Burkert, Anette; Hofmann, Margit

1983-01-01

101

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

102

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 grains. 2 1/2 cups of Various Vegetables 2 cups of Whole or Cut Fruit- avoid fruit juice as it lacks! Spinach- Rich in vitamins, minerals, and antioxidants Carrots- excellent source of vitamin A Brussel

Carter, John

103

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

104

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

E-print Network

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

Neal, Jack A.

2010-07-14

105

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

E-print Network

incident, involving fresh tomatoes and peppers rather than spinach, and Salmonella rather than E. coli. While every food recall is important and unique, the contamination of fresh spinach with the bacteria Were Intentional? Page 27 A Similar Incident: Tomatoes and Peppers Recall Page 28 Conclusions Page 30

Weiblen, George D

106

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

Microsoft Academic Search

This case summarizes the 2006 fresh spinach recall and questions prompted by one of the largest outbreaks of foodborne illness in the United States in recent years an estimated 4,000 cases. While every food recall is important and unique, the contamination of fresh spinach with the bacteria Escherichia coli (E. coli) O157:H7 during the summer and fall of 2006

Jonathan M. Seltzer; Jeff Rush; Jean D. Kinsey

2009-01-01

107

Chloroplast and cytosolic triosephosphate isomerases from spinach: purification, microsequencing and cDNA cloning of the chloroplast enzyme  

Microsoft Academic Search

Chloroplast and cytosolic triosephosphate isomerases from spinach were separated and purified to homogeneity. Both enzymes were partially sequenced by Edman degradation. Using degenerate primers designed against the amino acid sequences, a homologous probe for the chloroplast enzyme was amplified and used to isolate several full-size cDNA clones. Chloroplast triosephosphate isomerase is encoded by a single gene in spinach. Analysis of

Katrin Henze; Claus Schnarrenberger; Josef Kellermann; William Martin

1994-01-01

108

Vitamin A potency of carrot and spinach carotenes in human metabolic studies.  

PubMed

Changes in plasma retinol and carotenoids was measured in 17 young males after daily ingestion of grated carrots, carrot juice or spinach leaves for 2 weeks. Regression equations showed that the supply of 3350 and 4750 micrograms carotenes from 78 ml carrot juice (prepared from 185 g carrots) or 91 g grated carrots, respectively were adequate in maintaining plasma retinol at a constant level in subjects with initial plasma retinol of 1.2 mumol/l. Under similar experimental conditions, 280 g boiled spinach leaves providing 12,700 micrograms carotenes were required to maintain plasma retinol at a constant level. Apparent carotene digestibilities of 47 and 81% were obtained with carrot and spinach, respectively. PMID:2276879

Hussein, L; el-Tohamy, M

1990-01-01

109

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

110

20 Easy Ways to Increase Your Fruits & Veggies 1. Think veggies when topping your pizza. Try broccoli, spinach, green peppers, tomatoes,  

E-print Network

broccoli, spinach, green peppers, tomatoes, mushrooms and zucchini. 2. Mix up a breakfast smoothie made peppers, mushrooms and onions. 6. Make colorful salads using baby carrots, grape tomatoes, spinach leaves such as zucchini, spinach and carrots to lasagna, meat loaf, mashed potatoes, rice dishes and pasta sauces. 16

O'Toole, Alice J.

111

Solubilization of carotenoids from carrot juice and spinach in lipid phases: II. Modeling the duodenal environment.  

PubMed

We have been investigating the factors determining the bioavailability of carotenoids from vegetables. The previous paper [Rich, G.T., Bailey, A.L., Faulks, R.M., Parker, M.L., Wickham, M.S.J., and Fillery-Travis, A. (2003) Solubilization of Carotenoids from Carrot Juice and Spinach in Lipid Phases: I. Modeling the Gastric Lumen, Lipids 38, 933-945] modeled the gastric lumen and studied the solubilization pathway of carotenes and lutein from carrot juice and homogenized spinach to oil. Using the same vegetable preparations, we have extended our investigations to solubilization pathways potentially available in the duodenum and looked at the ease of solubilization of carotenes and lutein within simplified lipid micellar and oil phases present within the duodenum during digestion. Micellar solubility of raw spinach carotenoids was low and was enhanced by freezing, which involved a blanching step. The efficiency of solubilization of carotenoids in glycodeoxycholate micelles decreased in the order lutein(carrot) > lutein(blanched-frozen spinach) > carotene(blanched-frozen spinach) > carotene(carrot). Frozen spinach carotenoids were less soluble in simple micelles of taurocholate than of glycodeoxycholate. The results comparing the solubility of the carotenoids in mixed micelles (bile salt with lecithin) with simple bile salt micelles are explained by the relative stability of the carotenoid in the organelle compared to that in the micelle. The latter is largely determined by the polarity of the micelle. Below their critical micelle concentration (CMC), bile salts inhibit transfer of carotenoids from tissue to a lipid oil phase. Above their CMC, the bile salts that solubilize a carotenoid can provide an additional route to the oil from the tissue for that carotenoid by virtue of the equilibrium between micellar phases and the interfacial pathway. Mixed micellar phases inhibit transfer of both carotenoids from the tissue to the oil phase, thereby minimizing this futile pathway. PMID:14584602

Rich, Gillian T; Faulks, Richard M; Wickham, Martin S J; Fillery-Travis, Annette

2003-09-01

112

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

PubMed

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

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

2004-01-01

113

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

PubMed

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

Rothov, Olga; Hol, Dana; Ko?ov, Marie; T?mov, Lenka; Hnili?ka, Frantiek; Hnili?kov, Helena; Kamlar, Marek; Macek, Tom

2014-07-01

114

REMOTE SENSING TO ESTIMATE CHLOROPHYLL CONCENTRATION IN SPINACH USING MULTISPECTRAL PLANT REFLECTANCE  

Microsoft Academic Search

The presence of nitrogen in soil and chlorophyll in plants are directly related; thus, chlorophyll may be used as an indirect indicator of nitrogen levels in fertilizer management systems. This research investigated a non-destructive method of determining chlorophyll content and concentration in field-grown spinach. Biomass was estimated with percent vegetation coverage based on images taken with a multispectral imaging system.

C. L. Jones; P. R. Weckler; N. O. Maness; R. Jayasekara; M. L. Stone; D. Chrz

115

Regulation of photosynthetic carbon metabolism during phosphate limitation of photosynthesis in isolated spinach chloroplasts  

Microsoft Academic Search

Intact chloroplasts isolated from spinach were illuminated in the absence of inorganic phosphate (Pi) or with optimum concentrations of Pi added to the reaction medium. In the absence of Pi photosynthesis declined after the first 12 min and was less than 10% of the maximum rate after 5 min. Export from the chloroplast was inhibited, with up to 60% of

Christoph Giersch; Simon P. Robinson

1987-01-01

116

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

PubMed

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

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

2013-07-01

117

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

PubMed Central

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

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

2013-01-01

118

Changes in Mulberry Leaf Metabolism in Response to Water Stress  

Microsoft Academic Search

A series of experiments were conducted to characterize the water stress-induced changes in the activities of RuBP carboxylase (RuBPCO) and sucrose phosphate synthase (SPS), photosystem 2 activity, and contents of chlorophylls, carotenoids, starch, sucrose, amino acids, free proline, proteins and nucleic acids in mulberry (Morus alba L. cv. K-2) leaves. Water stress progressively reduced the activities of RuBPCO and SPS

P. Barathi; D. Sundar; A. Ramachandra Reddy

2001-01-01

119

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

120

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

Microsoft Academic Search

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

Marisa Porrini; Patrizia Riso; Giovannangelo Oriani

2002-01-01

121

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

122

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

Microsoft Academic Search

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

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

2007-01-01

123

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

PubMed

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

Akamatsu, Shigeki; Yoshioka, Naoki; Mitsuhashi, Takao

2012-01-01

124

Using Spinach-based sensors for fluorescence imaging of intracellular metabolites and proteins in living bacteria.  

PubMed

Genetically encoded fluorescent sensors can be valuable tools for studying the abundance and flux of molecules in living cells. We recently developed a novel class of sensors composed of RNAs that can be used to detect diverse small molecules and untagged proteins. These sensors are based on Spinach, an RNA mimic of GFP, and they have successfully been used to image several metabolites and proteins in living bacteria. Here we discuss the generation and optimization of these Spinach-based sensors, which, unlike most currently available genetically encoded reporters, can be readily generated to any target of interest. We also provide a detailed protocol for imaging ADP dynamics in living Escherichia coli after a change from glucose-containing medium to other carbon sources. The entire procedure typically takes ?4 d including bacteria transformation and image analysis. The majority of this protocol is applicable to sensing other metabolites and proteins in living bacteria. PMID:24356773

Strack, Rita L; Song, Wenjiao; Jaffrey, Samie R

2014-01-01

125

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

126

Cyclic electron transfer in plant leaf  

PubMed Central

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

Joliot, Pierre; Joliot, Anne

2002-01-01

127

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

PubMed

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

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

2010-04-01

128

Solubilization of carotenoids from carrot juice and spinach in lipid phases: I. Modeling the gastric lumen.  

PubMed

Our understanding of the factors determining the bioavailability of carotenoids from fruits and vegetables is poor. The apolar nature of carotenoids precludes their simple diffusion from the food structure to the absorption site at the enterocyte. Therefore, there is interest in the potential pathways for solubilization in the gut before absorption. We have studied the transfer of carotenoids from carrot juice and homogenized spinach into lipid phases that mimic the intestinal lumen at the start of digestion. In this paper we report on their transfer into olive oil under conditions pertaining to the gastric environment. A comparison between preparations of raw spinach and of carrot, in which the intact cells have been largely broken, suggests that the membrane-bound carotenoids of spinach are more resistant to transfer than the crystalline carotenoids of carrot. Lowering the pH and pepsin treatment enhance the transfer from raw vegetables. The process of blanching and freezing spinach destroys the chloroplast ultrastructure and leads to (i) a substantial increase in transfer of the carotenoids to oil and (ii) an attenuation or reversal of the enhancement of transfer seen with reduced pH or with pepsin treatment. Similar effects are seen after blanching carrot juice. Our results show that removal of soluble protein and denaturation of membrane proteins enhances the partition of carotenoids into oil. For both vegetables there is no evidence of preference in the extent of transfer of one carotenoid over another. This suggests that partitioning into oil under gastric conditions is not the stage of digestion that could lead to differences in carotenoid bioavailability. PMID:14584601

Rich, Gillian T; Bailey, Angela L; Faulks, Richard M; Parker, Mary L; Wickham, Martin S J; Fillery-Travis, Annette

2003-09-01

129

Response of spinach ( Spinacea oleracea) to the added fluoride in an alkaline soil  

Microsoft Academic Search

The influence of soil contamination by inorganic fluoride (NaF) on the uptake and accumulation of fluoride in the shoot and root of spinach (Spinacea oleracea) was investigated in pot experiment under controlled conditions. The soluble fluoride in soil varied between 2.57mgkg?1 soil and 16.44mgkg?1 soil in the treatment range of 0800mgNaFkg?1 soil. It was found that the concentration of the

S. K. Jha; A. K. Nayak; Y. K. Sharma

2008-01-01

130

Solubilization of carotenoids from carrot juice and spinach in lipid phases: II. Modeling the duodenal environment  

Microsoft Academic Search

We have been investigating the factors determining the bioavailability of carotenoids from vegetables. The previous paper\\u000a [Rich, G.T., Bailey, A.L., Faulks, R.M., Parker, M.L., Wickham, M.S.J., and Fillery-Travis, A. (2003) Solubilization of Carotenoids\\u000a from Carrot Juice and Spinach in Lipid Phases: I. Modeling the Gastric Lumen, Lipids 38, 933945] modeled the gastric lumen and studied the solubilization pathway of carotenes

Gillian T. Rich; Richard M. Faulks; Martin S. J. Wickham; Annette Fillery-Travis

2003-01-01

131

Biogenesis of photosystem I reaction center during greening of oat, bean and spinach leaves  

Microsoft Academic Search

SummaryThe relative amounts of some chloroplast polypeptides were followed during greening of leaves from three different plant families.\\u000a Oat, bean and spinach were the representatives of the Gramineae, Leguminosae and Chenopodiaceae, respectively. By using specific\\u000a antibodies against subunits of the chloroplast protein complexes, it was found with that method that the protein complexes\\u000a which are not involved in a photobiochemical

Rachel Nechushtai; Nathan Nelson

1985-01-01

132

?-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

133

Light activation of fructose bisphosphatase in isolated spinach chloroplasts and deactivation by hydrogen peroxide  

Microsoft Academic Search

Spinach chloroplast fructose bisphosphatase (EC 3.1.3.11.) exists in both oxidised and reduced forms. Only the latter has the kinetic properties that allow it to function at physiological concentrations of fructose 1,6-bisphosphate and Mg2+. Illumination of freshly prepared type A chloroplasts causes a conversion of oxidised to reduced enzyme. The rate of this conversion does not limit the rate of CO2

Stephen A. Charles; Barry Halliwell

1981-01-01

134

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 0.10.2 to 0.7 mm of the three plant species. Root hair

Doris Foehse; A. Jungk

1983-01-01

135

Hydration-state-responsive proteins link cold and drought stress in spinach  

Microsoft Academic Search

Spinach (Spinacia oleracea L.) seedlings exposed to low nonfreezing temperatures (010 C) that promote cold acclimation, synthesize a variety cold-acclimation proteins and at the same time acquire a greater ability to withstand cellular dehydration imposed by the freezing of tissue water. Two of these proteins (160 and 85 kDa) become more abundant over time at low temperature. In addition, a

Charles Guy; Dale Haskell; Lisa Neven; Paul Klein; Chris Smelser

1992-01-01

136

Response of spinach (Spinacea oleracea) to the added fluoride in an alkaline soil.  

PubMed

The influence of soil contamination by inorganic fluoride (NaF) on the uptake and accumulation of fluoride in the shoot and root of spinach (Spinacea oleracea) was investigated in pot experiment under controlled conditions. The soluble fluoride in soil varied between 2.57 mgkg(-1) soil and 16.44 mgkg(-1) soil in the treatment range of 0-800 mgNaF kg(-1) soil. It was found that the concentration of the total fluoride in shoot and root varied between 23.5 mgkg(-1) dry wt. (control) and 219.8 mgkg(-1) dry wt. (at 800 mgNaF kg(-1) soil). The fluoride concentration in shoot and root showed a linear trend. At the added fluoride concentration beyond 200 mgNaF kg(-1) of soil, the spinach root retained more fluoride than shoot. In the treatment range 0-800 mgNaF kg(-1) soil, the water labile fluoride in the juice varied from 0.32 to 0.78 ppm in shoot and 1.03 to 2.79 ppm in the root. No visible symptom of phyto-toxicity was noticed with the treatment from 0 to 800 mgNaF kg(-1) soil. It was inferred from this study that spinach (S. oleracea) accumulates fluoride at tissues level and has a distinct mechanism of partitioning of water labile fluoride and total fluoride in the tissues. PMID:18639373

Jha, S K; Nayak, A K; Sharma, Y K

2008-09-01

137

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.

138

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

PubMed Central

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

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

1991-01-01

139

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

140

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

141

Enzymic synthesis of the iron-sulfur cluster of spinach ferredoxin.  

PubMed

A biologically active spinach ferredoxin was reconstituted from the apoprotein by incubation with catalytic amounts of the sulfurtransferase rhodanese in the presence of thiosulfate, reduced lipoate and ferric ammonium citrate. Analytical and spectroscopical features of the reconstituted ferredoxin were identical to those of the native one; yield of the reconstitution reaction was 80%. Yields and kinetic parameters of the enzymic and chemical reconstitution were also compared. The higher efficiency of the enzymic system is ascribed to a productive interaction between rhodanese and apoferredoxin favouring the process of cluster build-up and insertion. The physiological relevance of this synthetic activity is discussed. PMID:6430704

Pagani, S; Bonomi, F; Cerletti, P

1984-07-16

142

BRIEF NOTES THE EFFECT OF MANGANESE DEFICIENCY STRUCTURE OF SPINACH CHLOROPLASTS ON THE  

E-print Network

Manganese is involved in the photosynthetic reactions of algae and leaves of higher plants (1-3). In tomato, manganese deficiency results in chloroplasts with a greatly reduced Hill reaction activity per unit chlorophyll (3). In spinach, manganese deficiency causes a 50 to 70 per cent reduction in the FMN-mediated photophosphorylation of isolated chloroplasts but only slightly affects the phosphorylation mediated by pyocyanine (4). Manganese is a constituent of the chloroplasts of higher plants. Photochemical activity of isolated chloroplasts is closely correlated with manganese content, and the manganese important in these reactions is not free ionic manganese but that bound within the chloroplast (5).

F. V. Mercer; Maret Nittim; J. V. Possingham; From Joint; Plant Physiology Unit

143

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

144

Possible association of actin filaments with chloroplasts of spinach mesophyll cells in vivo and in vitro.  

PubMed

In palisade mesophyll cells of spinach (Spinacia oleracea L.) kept under low-intensity white light, chloroplasts were apparently immobile and seemed to be surrounded by fine bundles of actin filaments. High-intensity blue light induced actin-dependent chloroplast movement concomitant with the appearance of a couple of long, straight bundles of actin filaments in each cell, whereas high-intensity red light was essentially ineffective in inducing these responses. The actin organization observed under low-intensity white light has been postulated to function in anchoring chloroplasts at proper intracellular positions through direct interaction with the chloroplasts. Intact chloroplasts, which retained their outer envelopes, were isolated after homogenization of leaves and Percoll centrifugation. No endogenous actin was detected by immunoblotting in the final intact-chloroplast fraction prepared from the leaves kept under low-intensity white light or in darkness. In cosedimentation assays with exogenously added skeletal muscle filamentous actin, however, actin was detected in the intact-chloroplast fraction precipitated after low-speed centrifugation. The association of actin with chloroplasts was apparently dependent on incubation time and chloroplast density. After partial disruption of the outer envelope of isolated chloroplasts by treatment with trypsin, actin was no longer coprecipitated. The results suggest that chloroplasts in spinach leaves can directly interact with actin, and that this interaction may be involved in the regulation of intracellular positioning of chloroplasts. PMID:17019524

Kumatani, T; Sakurai-Ozato, N; Miyawaki, N; Yokota, E; Shimmen, T; Terashima, I; Takagi, S

2006-11-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

146

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

147

Leaf to Landscape  

Microsoft Academic Search

\\u000a The capacity of terrestrial plant leaves for photosynthetic CO2 fixation per unit gram of leaf varies over 10-fold (Reich et al. 1997). The results of CO2 fixation, processing and subsequent accumulation of mass (Fig. 8.1) gives plants the most enormous variation in size of organisms\\u000a on earth (Niklas and Enquist 2001). The variation in photosynthetic capacity and in leaf form

David S. Ellsworth; lo Niinemets; Peter B. Reich

148

Leaf to Landscape  

Microsoft Academic Search

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

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

149

Effects of nano-anatase on spectral characteristics and distribution of LHCII on the thylakoid membranes of spinach.  

PubMed

In the article, we report that effects of nano-anatase on the spectral characteristics and content of light-harvesting complex II (LHCII) on the thylakoid membranes of spinach were investigated. The results showed that nano-anatase treatment could increase LHCII content on the thylakoid membranes of spinach and the trimer of LHCII; nano-anatase could enter the spinach chloroplasts and bind to PSII. Meanwhile, spectroscopy assays indicated that the absorption intensity of LHCII from nano-anatase-treated spinach was obviously increased in the red and the blue region, fluorescence quantum yield near 685 nm of LHCII was enhanced, the fluorescence excitation intensity near 440 and 480 nm of LHCII significantly rose and F 480/F 440 ratio was reduced. Oxygen evolution rate of PSII was greatly improved. Together, nano-anatase promoted energy transferring from chlorophyll (chl) b and carotenoid to chl a, and nano-anatase TiO2 was photosensitized by chl of LHCII, which led to enhance the efficiency of absorbing, transferring, and converting light energy. PMID:17916980

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

2007-01-01

150

The effects of ethylene, depressed oxygen and elevated carbon dioxide on antioxidant profiles of senescing spinach leaves  

Microsoft Academic Search

ascorbate. Glutathione content in the CA-stored tissue also significantly dropped, but only on day 35. In con- It has been suggested that antioxidants play a role in trast, spinach leaves stored in ambient air+ethylene regulating or modulating senescence dynamics of experienced a rapid decrease in levels of all the antiox- plant tissues. Ethylene has been shown to promote idants assessed

D. Mark Hodges; Charles F. Forney

2000-01-01

151

Replacing dried fish with fresh water spinach for growing pigs fed whole sugar cane stalks or cane juice  

Microsoft Academic Search

The experiment was conducted at CelAgrid (UTA, Cambodia), located in Kandal province. Whole sugar cane stalk and sugar cane juice were used as the sources of energy, and the protein source was the level of dry fish to provide 50, 100, 150 or 200 g protein per day. Fresh water spinach was chopped and fed ad libitum on the diets

Sorn Suheang; T R Preston

152

Bio-availability of iron from spinach ( Spanicia oleracea ) cultivated in soil fortified with graded levels of iron  

Microsoft Academic Search

In vitro availability of iron along with ascorbic acid, oxalic acid and phosphorus content of two varieties of spinach (Pusa Jyoti and Allgreen) cultivated in soil with different levels of added iron was determined. Addition of graded levels of iron to soil markedly increased the total iron and phosphorus contents and significantly decreased the bio-availability of iron, ascorbic acid and

N. Snehalatha Reddy; Vandana G. Malewar

1992-01-01

153

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

PubMed

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

Hausdorf, Lena; Mundt, Kerstin; Winzer, Michaela; Cordes, Christiana; Frhling, Antje; Schlter, Oliver; Klocke, Michael

2013-06-01

154

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

PubMed

In 2006, a large outbreak of Escherichia coli O157:H7 was linked to the consumption of ready-to-eat bagged baby spinach in the United States. The likely sources of preharvest 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 compared the transcriptional profiles of 12 E. coli O157:H7 isolates that possess the same two-enzyme pulsed-field gel electrophoresis (PFGE) profile and are related temporally or geographically to the above outbreak. These E. coli O157:H7 isolates included three clinical isolates, five isolates from separate bags of spinach, and single isolates from pasture soil, river water, cow feces, and a feral pig. The three clinical isolates and two spinach bag isolates grown in cultures to stationary phase showed decreased expression of many ?(S)-regulated genes, including gadA, osmE, osmY, and katE, compared with the soil, water, cow, feral pig, and the other three spinach bag isolates. The decreased expression of these ?(S)-regulated genes was correlated with the decreased resistance of the isolates to acid stress, osmotic stress, and oxidative stress but increases in scavenging ability. We also observed that intraisolate variability was much more pronounced among the clinical and spinach isolates than among the environmental isolates. Together, the transcriptional and phenotypic differences of the spinach outbreak isolates of E. coli O157:H7 support the hypothesis that some variants within the spinach bag retained characteristics of the preharvest isolates, whereas other variants with altered gene expression and phenotypes infected the human host. PMID:22081562

Parker, Craig T; Kyle, Jennifer L; Huynh, Steven; Carter, Michelle Q; Brandl, Maria T; Mandrell, Robert E

2012-01-01

155

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

SciTech Connect

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

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

1993-08-01

156

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

157

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

SciTech Connect

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

Joyard, J.; Douce, R. (Laboratoire Mixte CNRS/Rhone-Poulenc, Lyon (France)); Forest, E. (Centre d'Etudes Nucleaires de Grenoble (France)); Blee, E. (Institut de Botanique, Strasbourg (France))

1988-12-01

158

Causes for the Disappearance of Photosynthetic CO(2) Fixation with Isolated Spinach Chloroplasts.  

PubMed

When isolated spinach chloroplasts are illuminated, photosynthesis and CO(2) fixation die off within 30 to 90 minutes. Even when air levels of CO(2) are used which maintain high and rate-saturating amounts of ribulose 1,5-bisphosphate inside the plastids, CO(2) fixation declines. The decline begins with a drop in activity of the ribulose 1,5-bishosphate carboxylase/oxygenase, specifically loss of the enzyme-activator CO(2)-Mg(2+) form. Next, the light reactions cause gradual leakage of the carboxylase and other stromal proteins to the suspending medium. The chloroplast outer envelope appears to reseal and protect the thylakoids since there is little change in the ferricyanide-dependent Hill reaction. In the dark, under otherwise identical conditions, leakage of carboxylase does not occur. PMID:16664812

Seftor, R E; Jensen, R G

1986-05-01

159

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

SciTech Connect

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

Rustandi, R.R.; Snyder, S.W.; Feezel, L.L.; Michalski, T.J.; Norris, J.R.; Thurnauer, M.C.; Biggins, J. (Argonne National Laboratory, IL (USA))

1990-09-04

160

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

PubMed

Spinach starch debranching enzyme, a limit dextrinase or pullulanase (EC 3.2.1.41), is a monomeric protein of 100 kDa that produces up to seven coexisting and mutually interconvertible isomers of different specific activity, a phenomenon that has been termed microheterogeneity and for which a structural explanation has not yet been presented. The enzyme can be activated by reduction, in particular by thiol reagents, and inactivated by oxidation and the concomitant change of the patterns of its isomeric forms could be quantified by chromatofocusing. The hypothesis was examined that reduction of the enzyme's thiol groups shifts the isomer pattern towards the forms with a higher specific activity while oxidation favours the less active forms. Using TCEP as reductant only the form with the highest specific activity was obtained. This form was almost inaccessible for proteolysis by trypsin while the oxidized and GSH-activated enzyme yielded four peptides when treated with trypsin. Their sequence indicated cleavage predominantly of loops connecting the beta-strands and alpha-helices of the (beta/alpha)(8)-barrel which forms the catalytic site of the pullulanase. Formation of various disulphide bridges between the loops connecting the barrel structures -- predominantly on one side -- may be the reason for the microheterogeneity of the spinach pullulanase. In vivo, the enzyme maintains its activated state due to the high concentration of GSH in the chloroplast. However, the chloroplast's pH shifts from day (pH 8) to night (pH 7) and thus could also alter the activity of the protein in accordance with the required function in starch metabolism. PMID:11513962

Schindler, I; Renz, A; Schmid, F X; Beck, E

2001-08-13

161

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

162

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

PubMed

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

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

2009-08-01

163

An investigation of leaf mosaics  

Microsoft Academic Search

A field study of leaf mosaics of various species of flowering plants was undertaken as part of a course in photosynthesis. The work required little or no theoretical background knowledge. Leaf mosaics were observed, described, and classified into types. Features of the morphology and growth of each species which contributed to the formation of a leaf mosaic were recorded. The

E. L. Oxlade

1998-01-01

164

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

Microsoft Academic Search

A bacteriophage cocktail (designated ECP-100) containing three Myoviridae phages lytic for Escherichia coli O157:H7 was examined for its ability to reduce experimental contamination of hard surfaces (glass coverslips and gypsum boards), tomato, spinach, broccoli, and ground beef by three virulent strains of the bacterium. The hard surfaces and foods contaminated by a mixture of three E. coli O157:H7 strains were

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

2008-01-01

165

Influence of N-P-K fertilization on incidence and severity of oxidant injury to mangels and spinach  

Microsoft Academic Search

Experiments were performed to study the influence of nitrogen, potassium, and phosphorus on the sensitivity of plants to photochemical oxidant damage. Mangels and spinach were used as the test plants. Approximately equal amounts of ammonium and nitrate nitrogen were used with (NH)SO, KNO, and NHNO as the sources. Phosphate was added as Ca(HPO). Potassium was added as either KNO or

R. F. Brewer; F. B. GUILLEMENT; R. K. Creveling

1961-01-01

166

Synthesis of acyl-CoAs by isolated spinach chloroplasts in relation to added CoA and ATP  

Microsoft Academic Search

The kinetics of incorporation of [2-14C] acetate into lipids and acyl-CoAs in relation to added CoA and ATP by isolated spinach chloroplasts have been examined. The effect of the concentration of these cofactors on lipid and acyl-CoA synthesis was also studied. In the absence of cofactors, or when only one was present, the incorporation was very low and went mainly

J. Sanchez; M. Mancha

1981-01-01

167

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

Microsoft Academic Search

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

Bal Ram Singh; S M Imamul Huq; Shigenao Kawai

2008-01-01

168

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

169

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

PubMed Central

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

MacLeod, John K.

2006-01-01

170

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

NASA Astrophysics Data System (ADS)

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

Andrews, Joy Cooke

1995-01-01

171

The effect of chemical agents, beverages, and spinach on the in vitro solubilization of iron from cooked pinto beans.  

PubMed

The solubilization of iron from cooked pinto beans was examined using an improved in vitro methodology. The iron content of the beans was found to exist in three populations: 1) that which is spontaneously soluble upon incubation; 2) that which can be mobilized by chelating or reducing agents; and 3) that which is more firmly bound to the insoluble bean residue. These fractions constitute approximately 25, 45, and 30%, respectively, of the bean iron content when using consecutive 30-min incubations at pH 2 and 6. Ascorbic acid is maximally effective in iron mobilization under acidic conditions and acts via iron reduction. Citric acid is maximally effective near pH 6. The combination of ascorbic acid and citric acid leads to the solubilization of 70% of the iron content of the beans. Orange juice also leads to maximal soluble iron, predominantly in the Fe2+ state. Tea severely decreases iron solubility in the system. Only 3% of the iron content of spinach is solubilized by 10 mM ascorbic acid. Whole spinach suspension and the insoluble spinach residue are able to remove iron from solution that was previously solubilized from beans. PMID:7258129

Kojima, N; Wallace, D; Bates, G W

1981-07-01

172

Subcellular fractionation of polyprenyl diphosphate synthase activities responsible for the syntheses of polyprenols and dolichols in spinach leaves.  

PubMed

Polyisoprenoid alcohols occurring in spinach leaves were analyzed by a two-plate TLC method. Z,E-mixed polyprenols (C(55-60)), glycinoprenols (C(50-55)), and solanesol (C(45)) were mainly found in chloroplasts, whereas dolichols (C(70-80)) were mainly found in microsomes. Analysis of enzymatic products derived from [1-(14)C]isopentenyl diphosphate and farnesyl diphosphate (FPP) with subcellular fractions revealed that chloroplasts and microsomes had the ability to synthesize Z,E-mixed polyprenyl (C(50-65)) and all E-polyprenyl (C(45-50)) diphosphates, and Z,E-mixed polyprenyl (C(70-85)) diphosphates, respectively. FPP and geranylgeranyl diphosphate (GGPP) were both accepted for these enzymatic reactions, the former being a better substrate than the latter. NMR analysis of naturally occurring spinach Z,E-mixed polyprenol (C(55)) and dolichol (C(75)) revealed that the number of internal trans isoprene residues in the former was three in comparison with two internal trans residues found for the latter. These results indicate that two kinds of polyprenyl diphosphate synthases occur in spinach: One is the chloroplast enzyme involved in the synthesis of the shorter-chain (C(50-65)) Z,E-mixed polyprenols and the other is the microsomal enzyme involved in the synthesis of longer-chain (C(70-85)) Z,E-mixed polyprenols, which is converted to dolichols. PMID:11098151

Sakaihara, T; Honda, A; Tateyama, S; Sagami, H

2000-12-01

173

Absorption and transfer of light and photoreduction activities of spinach chloroplasts under calcium deficiency: promotion by cerium.  

PubMed

Chloroplasts were isolated from spinach cultured in calcium-deficient, cerium-chloride-administered calcium-present Hoagland's media or that of calcium-deficient Hoagland's media and demonstrated the effects of cerium on distribution of light energy between photosystems II and I and photochemical activities of spinach chloroplast grown in calcium-deficient media. It was observed that calcium deprivation significantly inhibited light absorption, energy transfer from LHCII to photosystemII, excitation energy distribution from PSI to PSII, and transformation from light energy to electron energy and oxygen evolution of chloroplasts. However, cerium treatment to calcium-deficient chloroplasts could obviously improve light absorption and excitation energy distribution from photosystem I to photosystem II and increase activity of whole chain electron transport, photosystems II and I DCPIP photoreduction, and oxygen evolution of chloroplasts. The results suggested that cerium under calcium deficiency condition could substitute for calcium in chloroplasts, maintain the stability of chloroplast membrane, and improve photosynthesis of spinach chloroplast, but the mechanisms still need further study. PMID:18193396

Hao, Huang; Ling, Chen; Xiaoqing, Liu; Chao, Liu; Weiqian, Cao; Yun, Lu; Fashui, Hong

2008-05-01

174

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

PubMed

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

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

2014-05-01

175

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

PubMed Central

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

2010-01-01

176

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

177

Thiol-Dependent Regulation of Glycerate Metabolism in Leaf Extracts 1  

PubMed Central

We have recently reported that the activity of maize leaf glycerate kinase [EC 2.7.1.31] is regulated in vivo by the light/dark transition, possibly involving the ferredoxin/thioredoxin mechanism, and that the stimulating effect of light can be mimicked in vitro by incubation of crude leaf extract with reducing compounds (LA Kleczkowski, DD Randall 1985 Plant Physiol 79: 274-277). In the present study it was found that the time course of thiol activation of the enzyme was substantially dependent on the presence of some low molecular weight inhibitor(s) of activation found both in leaf extracts and mesophyll chloroplasts. Activity of glycerate kinase from maize as well as wheat leaves increased upon greening of etiolated plants and was correlated with the development of photosynthetic apparatus in these species. The maize enzyme was strongly activated by thiols at all stages of development from etiolated to green seedlings. Thiol activation of glycerate kinase was observed for a number of C4 plants, notably of the nicotinamide adenine dinucleotide phosphate-malic enzyme type, with the strongest effect found for the enzyme from leaf extracts of maize and sorghum (10- and 8-fold activation, respectively). Among the C3 species tested, only the enzyme from soybean leaves was affected under the same conditions (1.6-fold activation). This finding was reflected by an apparent lack of cross-reactivity between the enzyme from maize leaves and antibodies raised against purified spinach leaf glycerate kinase. We suggest that, in addition to its role as a final step of photorespiration in leaves, glycerate kinase from C4 species may serve as a part of the facilitative diffusion system for the intercellular transport of 3-phosphoglycerate. Simultaneous operation of both the passive and the facilitative diffusion mechanisms of 3-phosphoglycerate transport in C4 plants is postulated. Images Fig. 6 PMID:16664873

Kleczkowski, Leszek A.; Randall, Douglas D.

1986-01-01

178

The organization and evolution of the spinach stress 70 molecular chaperone gene family.  

PubMed Central

The stress 70 molecular chaperones of plants are localized and function in all of the major subcellular compartments of the cell. Collectively, all of the various forms are encoded by a multigene family in the nucleus. At least 12 members of this family have been found, and sequence and DNA blot analyses provide an emerging description of the diversity of gene structure organization for this family of evolutionarily conserved proteins in spinach. They exhibit not only structural diversity in the organization of coding and noncoding regions but also distinct expression patterns for different tissues and abiotic conditions. The results of phylogenetic analyses are concordant with at least four major evolutionary events that gave rise to stress 70 molecular chaperones in each of four major subcellular compartments of plant cells: the plastid, mitochondrion, cytoplasm, and endoplasmic reticulum. The varied expression patterns also illustrate the complexity of effectively interpreting the role of any one of these stress-related proteins in response to abiotic stress in the absence of context to the other members of the family. PMID:9548981

Guy, C L; Li, Q B

1998-01-01

179

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

SciTech Connect

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

Heineke, D.; Heldt, H.W. (Universitaet Goettingen (West Germany)); Stitt, M. (Universitaet Bayreuth (West Germany))

1989-09-01

180

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

SciTech Connect

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

Schulze-Siebert, D.; Schultz, G.

1987-04-01

181

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

182

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

PubMed Central

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

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

2014-01-01

183

Herbicides affect fluorescence and electron transfer activity of spinach chloroplasts, thylakoid membranes and isolated Photosystem II.  

PubMed

In this work, studies on the effects produced by atrazine, terbutryn or diuron onto spinach photosynthetic materials were performed by observing changes in fluorescence emission and in electron transfer activities of the bio-samples in the presence of such herbicides; chloroplasts, thylakoids, Photosystem II-enriched thylakoids (BBYs) and isolated Photosystem II (PSII) were employed. This approach evidenced differences in the herbicide-photosynthetic material interactions going up-down from chloroplasts to proteins. Rapid emission increments were detected for chloroplasts and thylakoids, in particular in the presence of terbutryn; no remarkable emission increment was recorded when BBYs or PSII were used for this assay. The dependences of the chloroplast and thylakoid emission intensities upon herbicide concentration were investigated with responses even at concentrations below 10(-7)M. The influence of lowering the temperature was also tested, and the stabilizing effects on the resistances of the bio-samples against herbicides were recorded. Furthermore, Hill Reaction-based colorimetric assays were performed to monitor the electron transfer activities of the bio-samples in the presence of herbicides, after brief incubations. As a result, chloroplasts and thylakoids resulted to be sensitive tools in responding to concentrations even lower than 10(-7)M of most herbicides; nevertheless, an interesting sensitivity to herbicides was also observed for PSII. PMID:19962947

Ventrella, Andrea; Catucci, Lucia; Agostiano, Angela

2010-08-01

184

Siderin from Toona ciliata (Meliaceae) as photosystem II inhibitor on spinach thylakoids.  

PubMed

Four natural products were isolated from plants of the Rutaceae and Meliaceae families and their effect on photosynthesis was tested. Siderin (1) inhibited both ATP synthesis and electron flow (basal, phosphorylating, and uncoupled) from water to methylviologen (MV); therefore, it acts as Hill reaction inhibitor in freshly lysed spinach thylakoids. Natural products 2-4 were inactive. Secondary metabolite 1 did not inhibit PSI electron transport. It inhibits partial reactions of PSII electron flow from water to 2,6-dichlorophenol indophenol (DCPIP), from water to sodium silicomolybdate, and partially inhibits electron flow from diphenylcarbazid (DPC) to DCPIP. These results established that the site of inhibition of 1 was at the donor and acceptor sides of PSII, between P(680) and Q(A). Chlorophyll a fluorescence measurements confirmed the behavior of the Toona ciliate coumarin 1 as P(680) to Q(A) inhibitor by the creation of silent centers. May be this is the mechanisms of action of 1 and is the way in which it develops a phytotoxic activity against photosynthesis. PMID:17568558

Veiga, Thiago A M; Gonzlez-Vzquez, Raquel; Neto, Joo Oiano; Silva, Maria F G F; King-Daz, Beatriz; Lotina-Hennsen, Blas

2007-09-01

185

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

186

Evidence that pH can drive state transitions in isolated thylakoid membranes from spinach.  

PubMed

Our observation that the F735/F685 ratio at 77 K increased when the lumenal pH decreased led us to investigate the role of pH in explaining the mechanism of state transitions in spinach (Spinacea oleracea L.) thylakoid membranes. As the lumenal pH was changed from pH 7.5 to 5.5, the quantum yield of PS II decreased, while that of PS I increased. In the presence of an uncoupler, NH(4)Cl, which sequesters protons, a reversal of the effects observed at pH 5.5 were noticed. The thylakoid membranes treated with NaF at pH 5.5, when suspended in a buffer of pH 7.5, showed enhanced PS II fluorescence and a decreased PS I fluorescence, suggesting migration of LHC II back to PS II from PS I. The results presented here suggest for the first time that the lumenal pH of thylakoid membranes regulates the migration of antenna, and hence the energy distribution, between the two photosystems, i.e. a low lumenal pH (pH 5.5) favors antenna migration from PS II to PS I. At pH 7.5, the deprotonation of LHC II antenna attached to PS I leads to back migration of LHC II to PS II. PMID:20480090

Singh-Rawal, Pooja; Jajoo, Anjana; Mathur, Sonal; Mehta, Pooja; Bharti, Sudhakar

2010-06-01

187

Natural diterpenes from Croton ciliatoglanduliferus as photosystem II and photosystem I inhibitors in spinach chloroplasts.  

PubMed

In our search for new natural photosynthetic inhibitors that could lead to the development of "green herbicides" less toxic to environment, the diterpene labdane-8alpha,15-diol (1) and its acetyl derivative (2) were isolated for the first time from Croton ciliatoglanduliferus Ort. They inhibited photophosphorylation, electron transport (basal, phosphorylating and uncoupled) and the partial reactions of both photosystems in spinach thylakoids. Compound 1 inhibits the photosystem II (PS II) partial reaction from water to Na(+) Silicomolibdate (SiMo) and has no effect on partial reaction from diphenylcarbazide (DPC) to 2,6-dichlorophenol indophenol (DCPIP), therefore 1 inhibits at the water splitting enzyme and also inhibits PS I partial reaction from reduced phenylmetasulfate (PMS) to methylviologen (MV). Thus, it also inhibits in the span of P(700) to Iron sulfur center X (F(X)). Compound 2 inhibits both, the PS II partial reactions from water to SiMo and from DPC to DCPIP; besides this, it inhibits the photosystem I (PS I) partial reaction from reduced PMS to MV. With these results, we concluded that the targets of the natural product 2 are located at the water splitting enzyme, and at P(680) in PS II and at the span of P(700) to F(X) in PS I. The results of compounds 1 and 2 on PS II were corroborated by chlorophyll a fluorescence. PMID:17333505

Morales-Flores, Flix; Aguilar, Mara Isabel; King-Daz, Beatriz; de Santiago-Gmez, Jess-Ricardo; Lotina-Hennsen, Blas

2007-01-01

188

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

189

Simultaneous recovery of bacteria and viruses from contaminated water and spinach by a filtration method.  

PubMed

Water and leafy vegetables eaten fresh are increasingly reported as being involved in food-borne illness cases. The pathogenic agents responsible for these infections are mainly bacteria and viruses and are present in very small quantities on the contaminated food matrices. Laboratory techniques used to isolate or detect the contaminating agent differ enormously according to the type of microorganisms, generating time and economical losses. The purpose of this study was to optimize a single method which allows at the same time the recovery and concentration of these two main types of pathogenic organisms. Water and spinach samples were artificially contaminated with the feline calicivirus (FCV), rotavirus, hepatitis A virus (HAV), Escherichia coli, Listeria monocytogenes, Campylobacter jejuni and Salmonella Typhimurium. The principle behind the recovery technique is based on the use of a positively charged membrane which adsorbs both viruses and bacteria present in the water or in the rinse from the vegetables. Using conventional microbiology, PCR and RT-PCR, this filtration technique allowed a detection level superior to 10 CFU/g for S. Typhimurium, E. coli, L. monocytogenes and C. jejuni and to 10 PFU/g for FCV, HAV and rotavirus. This combined method can also be applied to other bacterial and viral species for the identification of the responsible agent for food-borne illnesses. PMID:21131086

Brassard, Julie; Guvremont, velyne; Gagn, Marie-Jose; Lamoureux, Lisyanne

2011-01-01

190

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

191

Isolation of a five-polypeptide cytochrome b-f complex from spinach chloroplasts.  

PubMed

A simple rapid purification of a cytochrome b-f complex from spinach chloroplasts is described. Novel features of the method include: 1) EDTA treatment of thylakoids prior to detergent extraction; 2) affinity chromatography over equine cytochrome c linked to Sepharose 4B; and 3) inclusion of the protease inhibitor phenylmethylsulfonyl fluoride. Cytochrome b-f complex is obtained in good yield, free of exogenous lipid, and with high plastoquinol:plastocyanin oxidoreductase activity. The complex contains 2 eq of cytochrome b-563 per eq of cytochrome f and a Rieske iron-sulfur center. Polyacrylamide gel electrophoresis in the presence of dodecyl sulfate indicates that the complex is composed of five distinct polypeptides of Mr = 37,000, 33,500, 22,000, 19,000, and 16,500. Only the Mr = 33,500 and 22,000 polypeptides stain for heme. The Mr = 37,000 component in this preparation is absent from cytochrome b-f complex isolated by another procedure (Hurt, E., and Hauska, G. (1981) Eur. J. Biochem. 117, 591-599). The complex described here also differs in its spectrum at 77 K, its stability, and its buoyant density. PMID:6885784

Clark, R D; Hind, G

1983-09-10

192

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

193

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

SciTech Connect

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

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

1993-05-01

194

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

SciTech Connect

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

Takahashi, Yasuhiro; Mitsui, Akira; Matsubara, Hiroshi (Osaka Univ. (Japan))

1991-01-01

195

Characterization of a photosynthesizing reconstituted spinach chloroplast preparation: regulation by primer, adenylates, ferredoxin, and pyridine nucleotides  

SciTech Connect

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

Kow, Y.W.; Gibbs, M.

1982-01-01

196

Leaf orientation and sunlit leaf area distribution in cotton  

Microsoft Academic Search

The diurnal leaf orientation behaviour of row-planted cotton plants (Gossypium hirsutum L. cv. DES 119) and its relationship to sunlit leaf area distribution at three stages of development were studied in the field. Electromagnetic digitizing was used for plant geometrical structure measurement for three periods of 2 h during the day. Cotton leaves showed a diaheliotropic response throughout the day.

Sornprach Thanisawanyangkura; Herve Sinoquet; Pierre Rivet; Michel Cretenet; Eric Jallas

1997-01-01

197

Estimation of Moisture in Maize Leaf by Measuring Leaf  

Microsoft Academic Search

Leaf moisture of maize was estimated by variation of dielectric constant. These variations are measured via designed and manufactured capacitive sensors. Capacitance was measured at two frequencies (100 kHz & 1 MHz). The results showed that in all cases the best fitted curve for variations of dielectric constant in relation to leaf moisture percentage was in the form of y=aebx

AMIN AFZAL; SAYED-FARHAD MOUSAVI

198

Short communication Leaf optical properties and photosynthetic leaf absorptances  

E-print Network

assessments of the photo-physiology of seagrasses (Beer et al., 2001). Pulse amplitude modulated (PAM of photosynthetically active radiation (PAR) at the leaf surface and the fraction of the PAR absorbed by the leaf (Beer et al., 1998, 2000, 2001; Beer and Bjo¨rk, 2000; Schreiber, 2004). The fraction of incident PAR

Durako, Michael J.

199

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

200

The effect of SO 3 -- on the activity of ribulose-1,5-diphosphate carboxylase in isolated spinach chloroplasts  

Microsoft Academic Search

SO3--inhibits the activity of ribulose-1,5-diphosphate carboxylase in isolated spinach chloroplasts. It shows a non-competitive inhibition pattern with respect to ribulose-1,5-diphosphate and Mg++ but a competitive one with respect to HCO3-. The Ki-values are 14 mM SO3--and 9.5 mM SO3-respectively for the non-competitive inhibition but only 3.0 mM SO3--in the case of competitive inhibition with HCO3--as a substrate. Thus it is

Irmgard Ziegler

1972-01-01

201

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

202

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

203

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

Microsoft Academic Search

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

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

204

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

PubMed

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

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

2013-07-01

205

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

206

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

SciTech Connect

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

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

1993-04-01

207

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

208

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

209

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

210

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

Microsoft Academic Search

A cDNA clone encoding a nonspecific lipid transfer protein from spinach (Spinacia oleracea) was isolated by probing a library with synthetic oligonucleotides based on the amino acid sequence of the protein. Determination of the DNA sequence indicated a 354-nucleotide open reading frame which encodes a 118-amino acid residue polypeptide. The first 26 amino acids of the open reading frame, which

W. R. Bernhard; S. Thoma; J. Botella; C. R. Somerville

1991-01-01

211

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 (4C) 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

212

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

213

Detection of low levels of Escherichia coli in fresh spinach by surface plasmon resonance spectroscopy with a TMB-based enzymatic signal enhancement method  

Microsoft Academic Search

The development of effective Escherichia coli (E. coli) sensors has been of great importance and urgent need to public health and safety in the wake of the spinach outbreak in California in 2006. We report here an enzymatic signal enhancement method for highly sensitive and fast detection of E. coli based on the generation of a mass-enhancing product at the

Matthew J. Linman; Kenneth Sugerman; Quan Cheng

2010-01-01

214

Alterations of the phylloepiphytic bacterial community associated with interactions of Escherichia coli O157:H7 during storage of packaged spinach at refrigeration temperatures.  

PubMed

This study investigated the effects of packaging and storage temperature on the spinach phylloepiphytic bacterial community and fate of Escherichia coli O157:H7. Freshly harvested spinach was rinsed and/or disinfected, packaged and stored under typical retail conditions (4 degrees C) or under temperature abuse conditions (10 degrees C) for a period of 15 days. The final population size of culturable epiphytic bacteria after 15 days of storage was not affected by the temperature of storage or the presence of E. coli O157:H7. However, analysis of the bacterial community using denaturing gradient gel electrophoresis of 16s rDNA revealed changes with time of storage and the presence of E. coli O157:H7. Excision and sequencing of prominent DGGE bands identified that the majority of sequences belonged to the phyla Actinobacteria, Bacteroidetes, Firmicutes and Alphaprotebacteria. After 10 days of storage at 4 degrees C or 10 degrees C the population became more dominated by psychrotrophic bacteria. Removal of the epiphytic bacteria resulted in significant increases in numbers of E coli O157:H7 at 10 degrees C and was associated with decreased expression of E. coli O157:H7 virulence (stxA, curli, eaeA) and stress response (rpoS, sodB) genes. In conclusion, storage temperature and time of storage of packaged spinach affected the diversity of the epiphytic spinach microbiota which influenced the growth, establishment, physiology and potentially virulence of E. coli O157:H7. PMID:20417396

Lopez-Velasco, Gabriela; Davis, Marjorie; Boyer, Renee R; Williams, Robert C; Ponder, Monica A

2010-06-01

215

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

216

Experiments in Whole Leaf Photosynthesis  

ERIC Educational Resources Information Center

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

Stewart, J. C.; And Others

1974-01-01

217

Why do leaf-tying caterpillars abandon their leaf ties?  

PubMed

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

Sliwinski, Michelle; Sigmon, Elisha

2013-01-01

218

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

NASA Astrophysics Data System (ADS)

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

Xue, Lihong; Yang, Linzhang

219

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

Microsoft Academic Search

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

Andrea Nardini; Sebastiano Salleo; Fabio Raimondo

2003-01-01

220

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

SciTech Connect

The role of hexokinase in carbohydrate degradation in isolated, intact chloroplasts was evaluated. This was accomplished by monitoring the evolution of [sup 14]CO[sub 2] from darkened spinach (Spinacia oleracea), maize (Zea mays) mesophyll, and Chlamydomonas reinhardtii chloroplasts externally supplied with [sup 14]C-labeled fructose, glucose, mannose, galactose, maltose, and ribose. Glucose and ribose were the preferred substrates with the Chlamydomonas and maize chloroplasts, respectively. The rate of CO[sub 2] release from fructose was about twice that from glucose in the spinach chloroplast. externally supplied ATP stimulated the rate of CO[sub 2] release. The pH optimum for CO[sub 2] release was 7.5 with ribose and fructose and 8.5 with glucose as substrates. Probing the outer membrane polypeptides of the intact spinach chloroplast with two proteases, trypsin and thermolysin, decreased [sup 14]CO[sub 2] release from glucose about 50% but had little effect when fructose was the substrate. Tryptic digestion decreased CO[sub 2] release from glucose in the Chlamydomonas chloroplast about 70%. [sup 14]CO[sub 2] evolution from [1-[sup 14]C]-glucose-6-phosphate in both chloroplasts was unaffected by treatment with trypsin. Enzymic analysis of the supernatant (stroma) of the lysed spinach chloroplast indicated a hexokinase active primarily with fructose but with some affinity for glucose. The pellet (membranal fraction) contained a hexokinase utilizing both glucose and fructose but with considerably less total activity than the stormal enzyme. Treatment with trypsin and thermolysin eliminated more than 50% of the glucokinase activity but had little effect on fructokinase activity in the spinach chloroplast. Tryptic digestion of the Chlamydomonas chloroplast resulted in a loss of about 90% of glucokinase activity. 34 refs., 2 figs., 6 tabs.

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

1993-06-01

221

Spectroscopic and kinetic properties of a recombinant form of the flavin domain of spinach NADH: nitrate reductase.  

PubMed

The C-terminal 268 residues of the spinach assimilatory NADH:nitrate reductase amino acid sequence that correspond to the flavin-containing domain of the enzyme have been selectively amplified and expressed as a recombinant protein in Escherichia coli. The recombinant protein, which was produced in both soluble and insoluble forms, was purified to homogeneity using a combination of ammonium sulfate precipitation, affinity chromatography on 5'-ADP-agarose and FPLC gel filtration. The purified domain exhibited a molecular weight of approximately 30 kDa, estimated by polyacrylamide gel electrophoresis, and a molecular mass of 30,169 for the apoprotein determined by mass spectrometry, which also confirmed the presence of FAD. The UV/visible spectrum was typical of a flavoprotein, with maxima at 272, 386, and 461 nm in the oxidized form while CD spectroscopy yielded both positive and negative maxima at 313 and 382 nm and 461 and 484 nm, respectively. The purified domain showed immunological cross-reactivity with anti-spinach nitrate reductase polyclonal antibodies while both N-terminal and internal amino acid sequencing of isolated peptides confirmed the fidelity of the domain's primary sequence. The protein retained NADH-ferricyanide reductase activity (Vmax=84 micromol NADH consumer/min/nmol FAD) with Km's of 17 and 34 microM for NADH and ferricyanide, respectively, with a pH optimum of approximately 6.5 A variety of NADH-analogs could also function as electron donors, though with decreased efficiency, the most effective being reduced nicotinamide hypoxanthine dinucleotide (V(max) = 35 micromol NHDH consumer/min/nmol FAD) and Km = 22 microM). NAD+ was demonstrated to be a competitive inhibitor (Ki = 1.9 mM) while analysis of inhibition by a variety of NAD+-analogs indicated the most efficient inhibitor to be ADP (Ki = 0.2 mM), with analogs devoid of either the phosphate, ribose, or adenine moieties proving to be markedly less-efficient inhibitors. The isolated domain was also capable of reducing cytochrome b5 directly (V(max) = 1.2 micromol NADH consumed/min/nmol FAD, Km (cyt. b5) = 6 microM), supporting the FAD -> b557 -> Mo electron transfer sequence in spinach nitrate reductase. PMID:8615685

Quinn, G B; Trimboli, A J; Prosser, I M; Barber, M J

1996-03-01

222

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

223

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

PubMed

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

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

2014-01-31

224

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

Microsoft Academic Search

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

Annika Brock; Thomas Hofmann

2008-01-01

225

Photosystem II Core Phosphorylation Heterogeneity, Differential Herbicide Binding, and Regulation of Electron Transfer in Photosystem II Preparations from Spinach 1  

PubMed Central

The effect of photosystem II core phosphorylation on the secondary quinone acceptor of photosystem II (QB) domain environment was analyzed by comparative herbicide-binding studies with photosystem II preparations from spinach (Spinacia oleracea L.). It was found that phosphorylation reduces the binding affinity for most photosynthetic herbicides. The binding of synthetic quinones and of the electron acceptor 2,6-dichlorophenolindophenol is also reduced by photosystem II phosphorylation. Four photosystem II core populations isolated from membranes showed different extents of phosphorylation as well as different degrees of affinity for photosynthetic herbicides. These findings support the idea that heterogeneity of photosystem II observed in vivo could be, in part, due to phosphorylation. Images Figure 1 PMID:16653222

Giardi, Maria T.; Rigoni, Fernanda; Barbato, Roberto

1992-01-01

226

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

PubMed Central

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

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

2008-01-01

227

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

Microsoft Academic Search

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

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

2008-01-01

228

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 with directions for finding mean, median, and mode are given. 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.

Shodor

2012-04-02

229

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

230

7 CFR 29.1028 - Leaf.  

Code of Federal Regulations, 2010 CFR

...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Flue-Cured Tobacco (u.s. Types 11, 12, 13, 14 and Foreign Type 92) 29.1028 Leaf. Whole, unstemmed leaf....

2010-01-01

231

In vivo antitumor effect of liposomes with sialyl LewisX including monogalactosyl diacylglycerol, a replicative DNA polymerase inhibitor, from spinach.  

PubMed

The glycoglycerolipid monogalactosyl diacylglycerol (MGDG) isolated from spinach selectively inhibits the activities of replicative DNA polymerase species and suppresses the growth of human cancer cell lines, while not affecting normal human cells. Liposomes, carrying surface-bound sialyl LewisX (SLX) and containing MGDG (SLX-Lipo-MGDG) and the fluorescent dye Cy5.5, were administered intravenously to mice bearing HT-29 human colon adenocarcinoma tumors and liposome distribution observed using fluorescence imaging equipment invivo. In an invivo antitumor assay on nude mice bearing HT-29 solid tumors, SLX-Lipo-MGDG was shown to be a stronger and more promising suppressor of solid tumors than MGDG alone. These results suggest that spinach MGDG could be developed into an anticancer compound, SLX-Lipo-MGDG could serve as an effective clinical anticancer drug and that these liposomes may be useful tools as the basis for active targeting drug delivery systems. PMID:22767329

Mizushina, Yoshiyuki; Hada, Takahiko; Yoshida, Hiromi

2012-09-01

232

SHADE TREE LEAF SCORCH1  

Microsoft Academic Search

The term scorch is commonly used to describe foliar symptoms of marginal and interveinal dessication. A diversity of abiotic and biotic agents cause scorch symptoms in shade trees. Thus there are many physiologic and pathologic bases for leaf scorch. Little research has been performed to define these bases; however, recent research involving fastidious xylem-inhabiting bacteria (FXIB) in elm, sycamore, oak,

R. Hammerschlag; J. Sherald; S. Kostka

1983-01-01

233

Leaf Photosynthesis Under Drought Stress  

Microsoft Academic Search

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

Gabriel Cornic; Angelo Massacci

234

Silicon-mediated changes of some physiological and enzymatic parameters symptomatic for oxidative stress in spinach and tomato grown in sodic-B toxic soil  

Microsoft Academic Search

We investigated effect of silicon (Si) on the growth, uptake of sodium (Na), chloride (Cl), boron (B), stomatal resistance\\u000a (SR), lipid peroxidation (MDA), membrane permeability (MP), lipoxygenase (LOX) activity, proline (PRO) accumulation, H2O2 accumulation, non-enzymatic antioxidant activity (AA) and the activities of major antioxidant enzymes (superoxide dismutase,\\u000a SOD; catalase, CAT and ascorbate peroxidase, APX) of spinach and tomato grown in

Aydin Gunes; Ali Inal; Esra Guneri Bagci; David J. Pilbeam

2007-01-01

235

Effect of high light intensities on oxygen evolution and the light activation of NADP-malate dehydrogenase in intact spinach chloroplasts  

Microsoft Academic Search

The factors limiting the photosynthetic carbon metabolism of intact spinach (Spinacia oleracea L.) chloroplasts after a high-light pretreatment have been studied. Photosynthetic CO2 fixation was decreased and became more sensitive to the inhibitory effect of the cyclic-electron-flow inhibitor, antimycin A. Depending on the extent of photoinhibition, changing the balance of linear to cyclic electron flow by adding oxaloacetate and antimycin

M. Miginiac-Maslow; G. Cornic; J.-P. Jacquot

1988-01-01

236

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

PubMed

A pot experiment was carried out to investigate the impact of Cd and Zn extractability in soil and speciation in pore water of industrial contaminated soils, on metal concentration in a metal sensitive species like spinach (Spinacia oleracea) and a more metal tolerant species like Italian ryegrass (Lolium multiflorum). For chemical speciation of Cd and Zn in pore water, WHAM/Model VI version 6.0 was used. The DGT technique was used to determine the effective concentration, C(E), of Cd and Zn in soils. The free ion activity in pore water correlated well with the contents in plants, and there was a linear relationship between the C(E) values and the concentration of Cd and Zn in both spinach and ryegrass in the non-toxic range. However, the C(E) values usually overestimated the plant contents when plants, particularly the spinach plants, were subjected to toxic concentration in the pore water. Metal uptake decreased in plants affected by toxicity, whereas metal binding to the Chelex resin did not. Thus, we found no linear relationship between the C(E) and metal contents in spinach, whereas a linear relationship was found between C(E)-Zn and the Zn concentration in ryegrass (r2=0.96, p<0.001). For Cd in ryegrass this relationship was weak (r2=0.53, p=0.18). This study indicates that the transport of metals from labile metal pools to the DGT-resin is linearly related to plant uptake only when plants are growing well, and that the applicability of DGT as an indicator for plant uptake seems species dependent. PMID:16084561

Alms, Asgeir R; Lombnaes, Peder; Sogn, Trine A; Mulder, Jan

2006-03-01

237

Antifungal peptides, a heat shock protein-like peptide, and a serinethreonine kinase-like protein from Ceylon spinach seeds  

Microsoft Academic Search

Two antifungal peptides (designated ?- and ?-basrubrins) with molecular masses of 45kDa and distinct N-terminal sequences, and a peptide and a protein with N-terminal sequences resembling heat shock protein (hsp) and serinethreonine kinase, respectively, were isolated from seeds of the Ceylon spinach Basella rubra. The purification procedure entailed saline extraction, (NH4)2SO4 precipitation, ion exchange chromatography on DEAE-cellulose, affinity chromatography on

Hexiang Wang; Tzi Bun Ng

2004-01-01

238

Ultrafast spectroscopy studies on the mechanism of electron transfer and energy conversion in the isolated pseudo ginseng, water hyacinth and spinach chloroplasts  

Microsoft Academic Search

The spectroscopy characteristics and the fluorescence lifetime for the chloroplasts isolated from the pseudo ginseng, water\\u000a hyacinth and spinach plant leaves have been studied by absorption spectra, low temperature steady-state fluorescence spectroscopy\\u000a and single photon counting measurement under the same conditions and by the same methods. The similarity of the absorption\\u000a spectra for the chloroplasts at room temperature suggests that

Sichuan Xu; Zhaoyong Sun; Xicheng Ai; Juan Feng; Qiyuan Zhang; Xingkang Zhang; Fei Yu; Chongqin Tang; Liangbi Li; Tingyun Kuang

2001-01-01

239

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

Microsoft Academic Search

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

Junichi Mano; Chiaki Ohno; Yoshinori Domae; Kozi Asada

2001-01-01

240

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

241

Tree branch angle: maximizing effective leaf area.  

PubMed

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

Honda, H; Fisher, J B

1978-02-24

242

Tree Branch Angle: Maximizing Effective Leaf Area  

Microsoft Academic Search

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

Hisao Honda; Jack B. Fisher

1978-01-01

243

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

244

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

245

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

246

7 CFR 29.3528 - Leaf surface.  

...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

247

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

248

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

249

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

250

Antioxidant assays - consistent findings from FRAP and ORAC reveal a negative impact of organic cultivation on antioxidant potential in spinach but not watercress or rocket leaves  

PubMed Central

Watercress (Rorippa nasturtium-aquaticum), wild rocket (Diplotaxis tenuifolia), and spinach (Spinacia oleracea) are commercial crops reported to have high concentrations of antioxidants, possibly contributing to disease prevention following human consumption. Following analysis of supermarket-purchased salad leaves, we report the antioxidant content potential of these species using two comparable techniques assessing the consistency between the assays by the ferric reducing antioxidant power (FRAP) assay and the oxygen radical absorbance capacity (ORAC) assay. The leaves were harvested from both conventionally and organically managed crops, to investigate whether organic agriculture results in improved crop quality. Watercress had the highest FRAP and ability to scavenge free radicals, followed by spinach and rocket. For watercress and rocket, there was no significant effect of organic agriculture on FRAP and ORAC, but for spinach, the antioxidant potential was reduced and this was significant at the 5% level of probability for FRAP but not ORAC, although the trend was clear in both tests. We conclude that there is variation in salad crop antioxidant potential and that FRAP and ORAC are useful techniques for measuring antioxidants in these salad crops with similar ranking for each salad crop studied. PMID:24804054

Payne, Adrienne C; Mazzer, Alice; Clarkson, Graham J J; Taylor, Gail

2013-01-01

251

Leafing patterns and leaf traits of four evergreen shrubs in the Patagonian Monte, Argentina  

NASA Astrophysics Data System (ADS)

We assessed leafing patterns (rate, timing, and duration of leafing) and leaf traits (leaf longevity, leaf mass per area and leaf-chemistry) in four co-occurring evergreen shrubs of the genus Larrea and Chuquiraga (each having two species) in the arid Patagonian Monte of Argentina. We asked whether species with leaves well-defended against water shortage (high LMA, leaf longevity, and lignin concentration, and low N concentration) have lower leaf production, duration of the leafing period, and inter-annual variation of leafing than species with the opposite traits. We observed two distinctive leafing patterns each related to one genus. Chuquiraga species produced new leaves concentrated in a massive short leafing event (5-48 days) while new leaves of Larrea species emerged gradually (128-258 days). Observed leafing patterns were consistent with simultaneous and successive leafing types previously described for woody plants. The peak of leaf production occurred earlier in Chuquiraga species (mid September) than in Larrea species (mid October-late November). Moreover, Chuquiraga species displayed leaves with the longest leaf lifespan, while leaves of Larrea species had the lowest LMA and the highest N and soluble phenolics concentrations. We also observed that only the leaf production of Larrea species increased in humid years. We concluded that co-occurring evergreen species in the Patagonian Monte displayed different leafing patterns, which were associated with some relevant leaf traits acting as plant defenses against water stress and herbivores. Differences in leafing patterns could provide evidence of ecological differentiation among coexisting species of the same life form.

Campanella, Mara Victoria; Bertiller, Mnica B.

2009-11-01

252

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

253

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

PubMed

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

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

2013-09-25

254

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

PubMed Central

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

Edwards, Gerald E.; Black, Clanton C.

1971-01-01

255

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

256

Knockout of major leaf ferredoxin reveals new redox-regulatory adaptations in Arabidopsis thaliana.  

PubMed

Ferredoxins are the major distributors for electrons to the various acceptor systems in plastids. In green tissues, ferredoxins are reduced by photosynthetic electron flow in the light, while in heterotrophic tissues, nicotinamide adenine dinucleotide (reduced) (NADPH) generated in the oxidative pentose-phosphate pathway (OPP) is the reductant. We have used a Ds-T-DNA insertion line of Arabidopsis thaliana for the gene encoding the major leaf ferredoxin (Fd2, At1g60950) to create a situation of high electron pressure in the thylakoids. Although these plants (Fd2-KO) possess only the minor fraction of leaf Fd1 (At1g10960), they grow photoautotrophically on soil, but with a lower growth rate and less chlorophyll. The more oxidized conditions in the stroma due to the formation of reactive oxygen species are causing a re-adjustment of the redox state in these plants that helps them to survive even under high light. Redox homeostasis is achieved by regulation at both, the post-translational and the transcriptional level. Over-reduction of the electron transport chain leads to increased transcription of the malate-valve enzyme NADP-malate dehydrogenase (MDH), and the oxidized stroma leads to an increased transcription of the OPP enzyme glucose-6-P dehydrogenase. In isolated spinach chloroplasts, oxidized conditions give rise to a decreased activation state of NADP-MDH and an activation of glucose-6-P dehydrogenase even in the light. In Fd2-KO plants, NADPH-requiring antioxidant systems are upregulated. These adjustments must be caused by plastid signals, and they prevent oxidative damage under rather severe conditions. PMID:18494733

Voss, Ingo; Koelmann, Meike; Wojtera, Joanna; Holtgrefe, Simone; Kitzmann, Camillo; Backhausen, Jan E; Scheibe, Renate

2008-07-01

257

Translocation of the potato 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase into isolated spinach chloroplasts  

SciTech Connect

A cDNA for potato (Solanum tuberosum L.) 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase, the first enzyme of the shikimate pathway, encodes a 56 KD polypeptide whose amino terminus resembles a chloroplast transit sequence. The cDNA was placed downstream of the phage T7 polymerase recognition sequence in plasmid pGEM-3Z. DNA of the resulting plasmid pGEM-DWZ directed T7 polymerase to synthesize potato DAHP synthase mRNA in vitro. The mRNA was used in wheat germ and rabbit reticulocyte lysates for the synthesis of {sup 35}S-labeled pro-DAHP synthase. The predominant translation product is a 59 KD polypeptide that can be immunoprecipitated by rabbit polyclonal antibodies raised against the 53 KD DAHP synthase purified from potato tubers. Isolated spinach chloroplasts process the 59 KD pro-DAHP synthase to a 50 KD polypeptide. The processed polypeptide is protected from protease degradation, suggesting uptake of the enzyme into the cell organelle. Fractionation of reisolated chloroplasts after import of pro-DAHP synthase showed mature enzyme in the stroma. The uptake and processing of DAHP synthase is inhibited by antibodies raised against the mature enzyme. Our results are consistent with the assumption that potato contains a nuclear DNA encoded DAHP synthase that is synthesized as a proenzyme and whose mature form resides in the chloroplasts. Our data provide further evidence that green plants synthesize aromatic amino acids in plastids.

Zhao, Jianmin; Weaver, L.M.; Herrmann, K.M. (Purdue Univ., West Lafayette, IN (USA))

1990-05-01

258

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

PubMed

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

Morales-Flores, Flix; Aguilar, Mara Isabel; King-Daz, Beatriz; Lotina-Hennsen, Blas

2013-08-01

259

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

PubMed

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

Chen, Keting; Arora, Rajeev

2011-02-01

260

Partial purification of a spinach thylakoid protein kinase that can phosphorylate light-harvesting chlorophyll a/b proteins  

SciTech Connect

Protein phosphorylation in plant tissues is particularly marked in chloroplasts, protein kinase activity being associated with the outer envelope, the soluble stromal fraction, and the thylakoid membrane. Furthermore, thylakoid-bound activity probably includes several distinct kinases, as suggested by studies of divalent cation specificity and thermal lability carried out with intact thylakoids and by subfractionation of solubilized membranes. Illumination of thylakoids, particularly with red light, promotes the rapid and extensive phosphorylation of the light-harvesting chlorophyll a/b complex (LHCII) on a threonine residue near the amino terminus of the protein. This phosphorylation is thought to be involved in regulating the distribution of absorbed quanta between photosystems II and I and is modulated by the redox state of the thylakoid plastoquinone pool. Neither of the thylakoid kinases reported to date was capable of phosphorylating purified LHCII in vitro or of incorporating phosphate into threonyl residues of exogenous substrates, that some LHCII phosphorylation was catalyzed by a preliminary fraction led workers to suggest that at least one other kinase remained to be isolated. Here, the authors report the solubilization and partial purification of a protein kinase from spinach thylakoids that is capable of phosphorylating LHCII in vitro, and they show that the specific site of phosphorylation is very nearly the same as, if not identical with, the site phosphorylated in organello.

Clark, R.D.; Hind, G.; Bennett, J.

1985-01-01

261

Leaf surface flavonoids of Chrysothamnus  

Microsoft Academic Search

Twenty-six flavonoid aglycones have been identified from eight plants covering three species of Chrysothamnus that were collected in eastern Oregon. The flavonoids were identified by NMR spectroscopy, tandem mass spectrometry and co-TLC with authentic markers. Chrysothamnus nauseosus yielded methyl ethers of apigenin, isoscutellarein, luteolin, kaempferol, herbacetin and quercetin. O-Methylated kaempferol and quercetin derivatives were isolated from the leaf exudate of

Jan F Stevens; Eckhard Wollenweber; Monika Ivancic; Victor L Hsu; Scott Sundberg; Max L Deinzer

1999-01-01

262

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

PubMed

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

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

2013-01-01

263

Leaf drop affects herbivory in oaks.  

PubMed

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

Pearse, Ian S; Karban, Richard

2013-11-01

264

Classification and quantification of leaf curvature.  

PubMed

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

2010-06-01

265

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

266

Alteration of Spinach Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Activase Activities by Site-Directed Mutagenesis  

PubMed Central

Site-directed mutagenesis was performed on the 1.6 and 1.9 kilobase spinach (Spinacea oleracea) ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase cDNAs, encoding the 41 and 45 kilodalton (kD) isoforms of the enzyme, to create single amino acid changes in the putative ATP-binding site of Rubisco activase (Lys-107, Gln-109, and Ser-112) and in an unrelated cysteine residue (Cys-256). Replacement of Lys-107 with Met produced soluble protein with reduced Rubisco activase and ATPase activities in both isoforms. Substituting Ala or Arg for Lys-107 produced insoluble proteins. Rubisco activase activity increased in the 41-kD isoform when Gln-109 was changed to Glu, but activity in the 45-kD isoform was similar to the wild-type enzyme. ATPase activity in the Glu-109 mutations did not parallel the changes in Rubisco activase activity. Rather, a higher ratio of Rubisco activase to ATPase activity occurred in both isoforms. The mutation of Gln-109 to Lys inactivated Rubisco activase activity. Replacement of Ser-112 with Pro created an inactive protein, whereas attempts to replace Ser-112 with Thr were not successful. The mutation of Cys-256 to Ser in the 45-kD isoform reduced both Rubisco activase and ATPase activities. The results indicate that the two activities of Rubisco activase are not tightly coupled and that variations in photosynthetic efficiency may occur in vivo by replacing the wild-type enzyme with mutant enzymes. ImagesFigure 3 PMID:16668989

Shen, Jennie B.; Ogren, William L.

1992-01-01

267

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

268

Differential response of chloride binding sites to elevated temperature: a comparative study in spinach thylakoids and PSII-enriched membranes.  

PubMed

A study of heat effects was performed in thylakoids and photosystem II (PSII)-enriched membranes isolated from spinach in relation to Cl(-)-induced activation of PSII catalyzed oxygen evolution and the retention of Cl(-) in the PSII complex. For this, Cl(-)-sufficient membranes and low-Cl(-) membranes were used. The presence of Cl(-) in the reaction medium did accelerate oxygen evolution, which remained unaffected by heat treatment up to 40 degrees C in PSII membranes and up to 42.5 degrees C in thylakoids. Heat resistance of Cl(-)-induced activation of oxygen evolution was found to be independent of the presence of 'bound Cl(-)' in the preparations. However, the functional stability of the PSII complex during heat treatment showed a marked dependence on the presence of bound Cl(-) in PSII. Electron paramagnetic resonance study of manganese (Mn) release per reaction center/Y (D) (+) showed that there was little loss of Mn(2+) up to 42 degrees C in our preparations, although the PSII activity was significantly lowered. These observations together with data from steady state chlorophyll a fluorescence imply that the site of action of Cl(-) causing direct activation of oxygen evolution was different from the site of primary heat damage. A differential response of chloride binding sites to heat stress was observed. The high-affinity (tightly bound, slow exchanging) site of chloride is affected earlier ( approximately 37 degrees C) while low-affinity (loosely bound, fast exchanging) site gets affected at higher temperatures (42.5 degrees C in thylakoids and 40 degrees C in the case of PSII-enriched membranes). PMID:17340213

Tiwari, Arjun; Jajoo, Anjana; Bharti, Sudhakar; Mohanty, Prasanna

2007-01-01

269

Pressure equilibrium and jump study on unfolding of 23-kDa protein from spinach photosystem II.  

PubMed

Pressure-induced unfolding of 23-kDa protein from spinach photosystem II has been systematically investigated at various experimental conditions. Thermodynamic equilibrium studies indicate that the protein is very sensitive to pressure. At 20 degrees C and pH 5.5, 23-kDa protein shows a reversible two-state unfolding transition under pressure with a midpoint near 160 MPa, which is much lower than most natural proteins studied to date. The free energy (DeltaG(u)) and volume change (DeltaV(u)) for the unfolding are 5.9 kcal/mol and -160 ml/mol, respectively. It was found that NaCl and sucrose significantly stabilize the protein from unfolding and the stabilization is associated not only with an increase in DeltaG(u) but also with a decrease in DeltaV(u). The pressure-jump studies of 23-kDa protein reveal a negative activation volume for unfolding (-66.2 ml/mol) and a positive activation volume for refolding (84.1 ml/mol), indicating that, in terms of system volume, the protein transition state lies between the folded and unfolded states. Examination of the temperature effect on the unfolding kinetics indicates that the thermal expansibility of the transition state and the unfolded state of 23-kDa protein are closer to each other and they are larger than that of the native state. The diverse pressure-refolding pathways of 23-kDa protein in some conditions were revealed in pressure-jump kinetics. PMID:15531632

Tan, Cui-Yan; Xu, Chun-He; Wong, Jun; Shen, Jian-Ren; Sakuma, Shinsuke; Yamamoto, Yasusi; Lange, Reinhard; Balny, Claude; Ruan, Kang-Cheng

2005-02-01

270

Effects of the sesquiterpene lactone tetraesters thapsigargicin and thapsigargin, from roots of Thapsia garganica L., on isolated spinach chloroplasts.  

PubMed

The effect of thapsigargicin and thapsigargin, extracted from the roots of Thapsia garganica L., on isolated photosynthetic membranes (thylakoids) and intact chloroplasts from spinach leaves (Spinacia oleracea L.) was investigated. Both sesquiterpene lactone tetraesters impair membranes and organelles in an identical, chlorophyll-dependent manner. In thylakoids these compounds primarily act as inhibitors of photophosphorylation. At lower sesquiterpene lactone tetraester/chlorophyll ratios, cyclic and non-cyclic photophosphorylation, ADP-stimulated electron transport and the photosynthetic control ratio progressively decreased with increasing concentrations of thapsigargicin and thapsigargin, whereas the state 4 electron flow, the coupling efficiency of photophosphorylation, the light-induced proton gradient, and the H+ flux across the membranes remained nearly unaffected. Half-maximal inhibition of photophosphorylation was obtained with 4-5 X 10(-7) moles sesquiterpene lactone tetraesters per mg chlorophyll. At higher sesquiterpene lactone tetraester/chlorophyll ratios, uncoupling of photophosphorylation from electron transport occurred. This was evident from stimulation of the state 4 electron flow, decline in the ADP/2e- ratio, increase in proton permeability and decrease in delta pH, whereas the uncoupled electron transport was only little impaired. In intact chloroplasts inhibition of HCO-3, 3-phosphoglycerate and oxaloacetate reduction by thapsigargicin and thapsigargin was not caused by inactivation of the photochemical reactions of the thylakoid membranes but were rather due to alterations in the permeability properties of the chloroplast envelope. This was concluded from similarities in the kinetics of these reactions. It is suggested that the highly lipid soluble sesquiterpene lactone tetraesters effectively disrupt the lipid-protein associations of biomembranes. PMID:3617076

Santarius, K A; Falsone, G; Haddad, H

1987-01-01

271

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

E-print Network

YIELD AND LEAF BLADE AREA COMPARISONS OF EXTRA LEAFY TO NORMAL LEAFED MAIZE ( Zea ~nays L. ) A Thesis RONALD WAYNE RUSHING Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1996 Major Subject: Plant Breeding YIELD AND LEAF BLADE AREA COMPARISONS OF EXTRA LEAFY TO NORMAL LEAFED MAIZE ( Zea mays L) A Thesis RONALD WAYNE RUSHING Submitted to Texas ASSAM University in partial...

Rushing, Ronald Wayne

2012-06-07

272

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...Standards of the United States for the Leaf Grade of American Upland Cotton 28.467 Leaf Grade 7. Leaf Grade 7 is leaf which is...

2010-01-01

273

Foliage height influences specific leaf area of three conifer species  

Microsoft Academic Search

Specific leaf area (SLA), the ratio of projected leaf area to leaf dry mass, is a critical parameter in many forest process models. SLA describes the efficiency with which the leaf captures light relative to the biomass invested in the leaf. It increases from top to bottom of a canopy, but it is unclear why. We sampled stands with low

John D. Marshall; Robert A. Monserud

2003-01-01

274

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

PubMed Central

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

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

2014-01-01

275

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

E-print Network

Leaf-wax n-alkanes record the plant­water environment at leaf ush Brett J. Tipple1 , Melissa A, UT, and approved December 26, 2012 (received for review August 13, 2012) Leaf-wax n-alkanes 2 H/1 H- ship between n-alkanes 2 H values and climate is appreciated, the quantitative details of the proxy

Tipple, Brett

276

Composition of speciose leaf litter alters stream detritivore growth, feeding activity and leaf breakdown  

Microsoft Academic Search

Leaf litter derived from riparian trees can control secondary production of detritivores in forested streams. Species-rich assemblages of leaf litter reflect riparian plant species richness and represent a heterogeneous resource for stream consumers. Such variation in resource quality may alter consumer growth and thus the feedback on leaf breakdown rate via changes in feeding activity. To assess the consequences of

Christopher M. Swan; Margaret A. Palmer

2006-01-01

277

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

SciTech Connect

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

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

1996-09-03

278

The effect of experimental warming on leaf functional traits, leaf structure and leaf biochemistry in Arabidopsis thaliana  

Microsoft Academic Search

BACKGROUND: The leaf is an important plant organ, and how it will respond to future global warming is a question that remains unanswered. The effects of experimental warming on leaf photosynthesis and respiration acclimation has been well studied so far, but relatively little information exists on the structural and biochemical responses to warming. However, such information is very important to

Biao Jin; Li Wang; Jing Wang; Ke-Zhen Jiang; Yang Wang; Xiao-Xue Jiang; Cheng-Yang Ni; Yu-Long Wang; Nian-Jun Teng

2011-01-01

279

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, Rene; Cepeda, Martha; Mazari-Hiriart, Marisa; Mena, Kristi D.

2012-01-01

280

Influence of irradiation, soil water potential, and leaf temperature on leaf morphology of a desert broadleaf, Encelia farinosa Gray (Compositae)  

Microsoft Academic Search

Laboratory experiments were performed to evaluate observed seasonal changes in leaf morphology of the desert perennial shrub, Encelia farinosa Gray. Plants were grown under low or high conditions of photosynthetically active irradiation, soil water potential (Psi\\/sup soil\\/), and leaf temperature (8 different experimental regimes). The relative growth rate, leaf water vapor conductance, leaf water potential, and leaf length were all

William K. Smith; Park S. Nobel

1978-01-01

281

"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

282

Feeding behavior of leaf beetles (Coleoptera, Chrysomelidae)  

Microsoft Academic Search

The feeding behavior of adult leaf beetles (41 species from 18 genera and 8 subfamilies) was studied for the first time. Beetles\\u000a of the genera Chrysolina, Chrysomela, Cryptocephalus, Galeruca, Gastrophysa, Labidostomis, Leptinotarsa, Timarcha, and Cassida stigmatica gnaw a leaf from the edge, whereas the representatives of Donacia, Galerucella, Lema, Lilioceris, Oulema, Phyllobrotica, Plagiodera, Zeugophora, Hypocassida, and most species of Cassida

A. O. Bie?kowski

2010-01-01

283

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

284

7 CFR 29.3035 - Leaf structure.  

...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

285

7 CFR 29.1030 - Leaf structure.  

...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

286

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

287

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

288

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2010 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,...

2010-01-01

289

7 CFR 29.2530 - Leaf structure.  

...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

290

7 CFR 29.3527 - Leaf structure.  

Code of Federal Regulations, 2010 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,...

2010-01-01

291

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

292

7 CFR 29.2530 - Leaf structure.  

Code of Federal Regulations, 2011 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,...

2011-01-01

293

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

294

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

295

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

296

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

297

7 CFR 29.3527 - Leaf structure.  

...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

298

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

299

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

300

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

301

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

302

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

303

7 CFR 28.471 - Below Leaf Grade Cotton.  

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

2014-01-01

304

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2013 CFR

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

2013-01-01

305

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2012 CFR

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

2012-01-01

306

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 12 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 (g 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

307

Nutrient Influences on Leaf Photosynthesis  

PubMed Central

The net rate of CO2 uptake for leaves of Gossypium hirsutum L. was reduced when the plants were grown at low concentrations of NO3-, PO42-, or K+. The water vapor conductance was relatively constant for all nutrient levels, indicating little effect on stomatal response. Although leaves under nutrient stress tended to be lower in chlorophyll and thinner, the ratio of mesophyll surface area to leaf area did not change appreciably. Thus, the reduction in CO2 uptake rate at low nutrient levels was due to a decrease in the CO2 conductance expressed per unit mesophyll cell wall area (gcellCO2). The use of gcellCO2 and nutrient levels expressed per unit of mesophyll cell wall provides a new means of assessing nutrient effects on CO2 uptake of leaves. PMID:16661231

Longstreth, David J.; Nobel, Park S.

1980-01-01

308

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

309

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

310

Binding of hydroxylamine to the water-oxidizing complex and the ferroquinone electron acceptor of spinach photosystem II  

SciTech Connect

The reaction between spinach photosystem II (PSII) membranes and hydroxylamine has been investigated by equilibrium titrations and flash-induced reactions with electron paramagnetic resonance (EPR) spectroscopy to monitor the odd-electron species, O/sub 2/ evolution rate, and manganese binding. Two high-affinity sites for NH/sub 2/OH reaction have been characterized. Binding to the first site occurs within the water-oxidizing complex (WOC) and produces the well-known two flash shift in O/sub 2/ evolution. The usual two-electron shift in O/sub 2/ yield is accompanied by a parallel two-electron shift in the yield of the S/sub 2/ multiline EPR signal. The two flash delay in turnover seen at room temperature is lost at low temperatures (150-500 K) due to a block in multiple turnovers caused by NH/sub 2/OH. The site for the low-temperature blockage is undetermined but correlates with the structural change at the ferroquinone site. This suggests that the reoxidation of Q/sub A//sup -/ by Q/sub B/ following turnover is blocked, resulting instead in recombination upon warming. The reversible loss of both of the S/sub 2/-state EPR signals, the multiline and the g = 4.1 signals, caused by NH/sub 2/OH, titrated with identical curves, suggesting a common chemical reactivity and hence origin for these signals. The reaction between the S/sub 2/ state and NH/sub 2/OH occurs in less than 10 s and is considerably faster than binding to the (dark) SV3exclamation state. The reversible binding of NH/sub 2/OH produces no stable paramagnetic products in the dark. The release of MN by NO/sub 2/OH is followed by reduction of the oxidized donor D/sup +/ responsible for EPR signal II/sub slow/ and signal II/sub dark/, confirming earlier work establishing the accessibility of this donor to the aqueous phase through the Mn binding site.

Sivaraja, M.; Dismukes, G.C.

1988-05-03

311

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

PubMed

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

Shaw, W H; Anderson, J W

1974-04-01

312

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

PubMed Central

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

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

1974-01-01

313

Quantification of the Antimicrobial Substances Produced by Lactic Acid Bacteria used as an Intervention to Inhibit Escherichia coli O157:H7 and Salmonella in vitro and on Fresh Spinach (Spinacia oleracea)  

E-print Network

is not completely understood. Therefore, the objectives of this research were to (i) determine the LAB dose required for inhibition of Escherichia coli O157:H7 and Salmonella enterica in vitro and on spinach, and (ii) identify and quantify the major antimicrobial...

Calix Lara, Thelma

2012-02-14

314

Global leaf trait relationships: mass, area, and the leaf economics spectrum.  

PubMed

The leaf economics spectrum (LES) describes multivariate correlations that constrain leaf traits of plant species primarily to a single axis of variation if data are normalized by leaf mass. We show that these traits are approximately distributed proportional to leaf area instead of mass, as expected for a light- and carbon dioxide-collecting organ. Much of the structure in the mass-normalized LES results from normalizing area-proportional traits by mass. Mass normalization induces strong correlations among area-proportional traits because of large variation among species in leaf mass per area (LMA). The high LMA variance likely reflects its functional relationship with leaf life span. A LES that is independent of mass- or area-normalization and LMA reveals physiological relationships that are inconsistent with those in global vegetation models designed to address climate change. PMID:23539179

Osnas, Jeanne L D; Lichstein, Jeremy W; Reich, Peter B; Pacala, Stephen W

2013-05-10

315

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

PubMed Central

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

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

2011-01-01

316

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

Microsoft Academic Search

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

Michael J. Durako

317

Animal behaviour Ancient death-grip leaf  

E-print Network

Ophiocordyceps unilateralis. In this system, ants attach to major leaf veins along their abaxial surface in a similar manner to O. unilateralis [5] and so this type of manipulation is a probable candi- date

318

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2010 CFR

...COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes...semimanufactured tobacco, stems which have been removed from leaves, cuttings, clippings, trimmings, shorts, or...

2010-01-01

319

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2011 CFR

...COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes...semimanufactured tobacco, stems which have been removed from leaves, cuttings, clippings, trimmings, shorts, or...

2011-01-01

320

7 CFR 30.2 - Leaf tobacco.  

Code of Federal Regulations, 2012 CFR

...COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO STOCKS AND STANDARDS Classification of Leaf Tobacco Covering Classes...semimanufactured tobacco, stems which have been removed from leaves, cuttings, clippings, trimmings, shorts, or...

2012-01-01

321

7 CFR 29.1029 - Leaf scrap.  

Code of Federal Regulations, 2010 CFR

...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Flue-Cured Tobacco (u.s. Types 11, 12, 13, 14 and Foreign Type 92) 29.1029 Leaf scrap. A byproduct of...

2010-01-01

322

7 CFR 29.1030 - Leaf structure.  

Code of Federal Regulations, 2010 CFR

...AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS TOBACCO INSPECTION Standards Official Standard Grades for Flue-Cured Tobacco (u.s. Types 11, 12, 13, 14 and Foreign Type 92) 29.1030 Leaf structure. The cell...

2010-01-01

323

Interaction between photons and leaf canopies  

NASA Technical Reports Server (NTRS)

The physics of neutral particle interaction for photons traveling in media consisting of finite-dimensional scattering centers that cross-shade mutually is investigated. A leaf canopy is a typical example of such media. The leaf canopy is idealized as a binary medium consisting of randomly distributed gaps (voids) and regions with phytoelements (turbid phytomedium). In this approach, the leaf canopy is represented by a combination of all possible open oriented spheres. The mathematical approach for characterizing the structure of the host medium is considered. The extinction coefficient at any phase-space location in a leaf canopy is the product of the extinction coefficient in the turbid phytomedium and the probability of absence gaps at that location. Using a similar approach, an expression for the differential scattering coefficient is derived.

Knyazikhin, Yuri V.; Marshak, Alexander L.; Myneni, Ranga B.

1991-01-01

324

The red edge of plant leaf reflectance  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

325

Coca leaf as a therapeutic agent.  

PubMed

South American Indians have used coca leaf as a remedy for thousands of years. Coca might be useful as a treatment for gastrointestinal ailments and motion sickness, as a fast-acting antidepressant medication, as a substitute stimulant for coffee in certain cases, and as an adjunct in programs of weight reduction and physical fitness. In leaf form, coca does not produce toxicity or dependence. Its effects are distinct from those of cocaine, which is but one of a number of active compounds in the leaf. Coca can be administered as a chewing gum containing a whole extract of the leaf, including alkaloids, natural flavors, and several nutrients. Legal mechanisms exist for importing, distributing, and dispensing coca, and experimentation with it by interested physicians would be valuable. PMID:696708

Weil, A T

1978-01-01

326

Reflectance model of a plant leaf  

NASA Technical Reports Server (NTRS)

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

Kumar, R.; Silva, L.

1973-01-01

327

7 CFR 29.1163 - Smoking Leaf (H Group).  

...2014-01-01 2014-01-01 false Smoking Leaf (H Group). 29.1163 Section...INSPECTION Standards Grades 29.1163 Smoking Leaf (H Group). This group...Tolerances H3FGood Quality Orange Smoking Leaf Mellow, open leaf...

2014-01-01

328

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Smoking Leaf (H Group). 29.1163 Section...INSPECTION Standards Grades 29.1163 Smoking Leaf (H Group). This group...Tolerances H3FGood Quality Orange Smoking Leaf Mellow, open leaf...

2013-01-01

329

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

330

7 CFR 29.1163 - Smoking Leaf (H Group).  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Smoking Leaf (H Group). 29.1163 Section...INSPECTION Standards Grades 29.1163 Smoking Leaf (H Group). This group...Tolerances H3FGood Quality Orange Smoking Leaf Mellow, open leaf...

2012-01-01

331

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 H3FGood Quality Orange Smoking Leaf Mellow, open leaf...

2011-01-01

332

7 CFR 28.471 - Below Leaf Grade Cotton.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

333

7 CFR 28.514 - Leaf Grade No. 4.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Leaf Grade No. 4. 28.514 Section 28.514 Agriculture...Standards of the United States for the Leaf Grade of American Pima Cotton 28.514 Leaf Grade No. 4. Leaf grade No. 4 shall be...

2010-01-01

334

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 Agriculture...Standards of the United States for the Leaf Grade of American Pima Cotton 28.512 Leaf Grade No. 2. Leaf grade No. 2 shall be...

2010-01-01

335

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 Agriculture...Standards of the United States for the Leaf Grade of American Pima Cotton 28.515 Leaf Grade No. 5. Leaf grade No. 5 shall be...

2010-01-01

336

7 CFR 28.516 - Leaf Grade No. 6.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Leaf Grade No. 6. 28.516 Section 28.516 Agriculture...Standards of the United States for the Leaf Grade of American Pima Cotton 28.516 Leaf Grade No. 6. Leaf grade No. 6 shall be...

2010-01-01

337

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 Agriculture...Standards of the United States for the Leaf Grade of American Pima Cotton 28.511 Leaf Grade No. 1. Leaf grade No. 1 shall be...

2010-01-01

338

ORIGINAL PAPER Leaf shape variation and herbivore consumption  

E-print Network

ORIGINAL PAPER Leaf shape variation and herbivore consumption and performance: a case study online: 9 January 2008 ? Springer Science+Business Media B.V. 2008 Abstract The effect of leaf shape of leaf shape variation on herbivore consumption and performance. We investigated whether alternative leaf

Stinchcombe, John

339

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

340

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

341

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

342

Vegetative Development: Total Leaf Area and Surface Area Indexes  

Microsoft Academic Search

\\u000a Canopy management determines canopy shape and spatial leaf area distribution which in turn determines vineyard productivity.\\u000a There are two indexes evaluating vineyard productivity which involve leaf development: total leaf area LAI and external\\u000a leaf area SA . The first one refers to total leaf area developed per m2 of soil while SA refers to the external leaves,

Patricia Snchez-de-Miguel; Pilar Baeza; Pedro Junquera; Jos Ramn Lissarrague

343

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

PubMed

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

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

2002-09-01

344

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

345

Regulation of leaf morphology by microRNA394 and its target LEAF CURLING RESPONSIVENESS.  

PubMed

The present study identified Arabidopsis miR394 and its target, an F-box (SKP1-Cullin/CDC53-F-box) gene At1g27340 (here referred to as LEAF CURLING RESPONSIVENESS, LCR), for regulation of leaf curling-related morphology. The loss-of-function lcr mutants exhibit pleiotropic defects with semi-dwarfism, altered leaf shape and a shorter stem. Overexpression of an miR394-resistant version of LCR under the 35S promoter (35S:m5LCR) and target mimicry MIM394 resulted in a curled-down leaf defect. Conversely, transgenic plants overexpressing 35S:MIR394a/b display a curled-up leaf phenotype. Detailed analyses show that there is a certain level of LCR that is optimal for leaf morphology, but lower or higher levels lead to abnormal leaf development, indicating that expression of miR394 in the leaf lamina is necessary for proper leaf morphology. Because the phytohormone auxin plays a crucial role in leaf morphogenesis and patterning, the DR5-GUS reporter gene was used to monitor the auxin response. We show that DR5 expression patterns in lcr and 35S::m5LCR plants were significantly different from those in the wild type. Also, overexpression of LCR in 35S::m5LCR plants drastically decreased the expression of the auxin-responsive genes IAA3, AXR3 and IAMT1, whereas increased expression of the genes was found in 35S::MIR394a plants. These results indicate that miR394 and its target LCR are involved in the regulation of leaf development. PMID:22619471

Song, Jian Bo; Huang, Si Qi; Dalmay, Tamas; Yang, Zhi Min

2012-07-01

346

Determination of six neonicotinoid insecticides residues in spinach, cucumber, apple and pomelo by QuEChERS method and LC-MS/MS.  

PubMed

A modified QuEChERS and LC-MS/MS method has been developed for the simultaneous determination of residues of six neonicotinoids in various crops, including spinach, cucumber, apple and pomelo. The method showed good linearity (R(2) ? 0.9995) and precision (RSD ? 14.0%). Average recoveries of the six neonicotinoids ranged between 73.7% and 103.8% at spiking levels 0.005, 0.1 and 1 mg kg(-1). The LODs and LOQs were in the ranges of 0.20-0.85 ?g kg(-1) and 0.66-2.84 ?g kg(-1), respectively. The method was satisfactorily validated for the analysis of 50 agricultural samples. Imidacloprid and imidaclothiz were detected at concentration levels ranging from 7 to 5.3 ?g kg(-1). PMID:22398693

Zhang, Fengzu; Li, Yanjie; Yu, Chuanshan; Pan, Canping

2012-06-01

347

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

348

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

PubMed

We report the isolation of Campylobacter species from the same population of feral swine that was investigated in San Benito County, California, during the 2006 spinach-related Escherichia coli O157:H7 outbreak. This is the first survey of Campylobacter in a free-ranging feral swine population in the United States. Campylobacter species were cultured from buccal and rectal-anal swabs, colonic faeces and tonsils using a combination of selective enrichment and antibiotic-free membrane filtration methods. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS, Bruker Daltonics, Inc., Billerica, MA, USA) was used to identify species followed by confirmatory multiplex PCR or 16S rRNA sequencing. Genetic relatedness of Campylobacter jejuni and Campylobacter coli strains was determined by multilocus sequence typing (MLST) and porA allele sequencing. Altogether, 12 (40%) of 30 feral swine gastrointestinal and oral cavity specimens were positive, and six species were isolated: Campylobacter coli, Campylobacter fetus, Campylobacter hyointestinalsis, Campylobacter jejuni, Campylobacter lanienae and Campylobacter sputorum. Campylobacter jejuni subtypes were closely related to MLST sequence type 21 (ST-21) and had identical porA sequences. Campylobacter coli subtypes were unrelated to isolates in the pubMLST/porA database. This feral swine population lived in close association with a 'grassfed' beef cattle herd adjacent to spinach and other leafy green row crop fields. The findings underscore the importance of protecting raw vegetable crops from faecal contamination by wild or feral animals. The study also illustrates a potential risk of Campylobacter exposure for hunters during handling and processing of wild swine meat. PMID:22405465

Jay-Russell, M T; Bates, A; Harden, L; Miller, W G; Mandrell, R E

2012-08-01

349

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

PubMed

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

Chen, Keting; Arora, Rajeev

2014-03-01

350

Quality control of photosystem II: direct imaging of the changes in the thylakoid structure and distribution of FtsH proteases in spinach chloroplasts under light stress.  

PubMed

Under light stress, the reaction center-binding protein D1 of PSII is photo-oxidatively damaged and removed from PSII complexes by proteases located in the chloroplast. A protease considered to be responsible for degradation of the damaged D1 protein is the metalloprotease FtsH. We showed previously that the active hexameric FtsH protease is abundant at the grana margin and the grana end membranes, and this homo-complex removes the photodamaged D1 protein in the grana. Here, we showed a change in the distribution of FtsH in spinach thylakoids during excessive illumination by transmission electron microscopy (TEM) and immunogold labeling of FtsH. The change in distribution of the protease was accompanied by structural changes to the thylakoids, which we detected using spinach leaves by TEM after chemical fixation of the samples. Quantitative analyses showed several characteristic changes in the structure of the thylakoids, including shrinkage of the grana, outward bending of the marginal portions of the thylakoids and an increase in the height of the grana stacks under excessive illumination. The increase in the height of the grana stacks may include swelling of the thylakoids and an increase in the partition gaps between the thylakoids. These data strongly suggest that excessive illumination induces partial unstacking of the thylakoids, which enables FtsH to access easily the photodamaged D1 protein. Finally three-dimensional tomography of the grana was recorded to observe the effect of light stress on the overall structure of the thylakoids. PMID:24891560

Yoshioka-Nishimura, Miho; Nanba, Daisuke; Takaki, Takashi; Ohba, Chikako; Tsumura, Nodoka; Morita, Noriko; Sakamoto, Hirotaka; Murata, Kazuyoshi; Yamamoto, Yasusi

2014-07-01

351

Effects of leaf-transmittance versus leaf-reflectance on bidirectional scattering from canopy\\/soil surface: An analytical study  

Microsoft Academic Search

A simple single-scattering model for a surface with sparse ereetophile plants is developed as a plane-parallel canopy consisting of small leaves (relative to leaf-to-leaf spacing) with a spherical-shell distribution of the leaf area. The contributions to the overall surface reflectance in the visible spectral bands by the soil-reflectance, leaf-reflection, and leaf-transmission (which are assumed isotropic) are analyzed under different view\\/illumination

J. Otterman; T. Brakke; J. Smith

1995-01-01

352

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

PubMed

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

Pantin, Florent; Simonneau, Thierry; Muller, Bertrand

2012-10-01

353

Phase identity of the maize leaf is determined after leaf initiation  

PubMed Central

The vegetative development of the maize shoot can be divided into juvenile and adult phases based on the types of leaves produced at different times in shoot development. Models for the regulation of phase change make explicit predictions about when the identity of these types of leaves is determined. To test these models, we examined the timing of leaf type determination in maize. Clones induced in transition leaf primordia demonstrated that the juvenile and adult regions of these leaves do not become clonally distinct until after the primordium is 700 ?m in length, implying that these cell fates were undetermined at this stage of leaf development. Adult shoot apices were cultured in vitro to induce rejuvenation. We found that leaf primordia as large as 3 mm in length can be at least partially rejuvenated by this treatment, and the location of rejuvenated tissue is correlated with the maturation pattern of the leaf. The amount and distribution of juvenile tissue in rejuvenated leaves suggests that rejuvenation occurs nearly simultaneously in all leaf primordia. In vitro culture rejuvenated existing leaf primordia and the P0 primordium, but did not change the identity of subsequent primordia or the total number of leaves produced by the shoot. This result suggests that leaf identity can be regulated independently of the identity of the shoot apical meristem, and it implies that vegetative phase change is not initiated by a change in the identity of the shoot apical meristem. PMID:10973480

Orkwiszewski, Joseph A. J.; Poethig, R. Scott

2000-01-01

354

Leaf alkaloids, phenolics, and coffee resistance to the leaf miner Leucoptera coffeella (Lepidoptera: Lyonetiidae).  

PubMed

Coffee (Coffea spp.) alkaloids (caffeine and related methylxanthines) and phenolics (caffeic and chlorogenic acids) have recognized pestistatic/pesticidal activity and mediate insect-plant interactions. The present investigation assessed the resistance of 12 coffee genotypes to the leaf miner Leucoptera (= Perileucoptera) coffeella (Gurin-Mneville & Perrottet) (Lepidoptera: Lyonetiidae) and correlated such results with the leaf content of coffee alkaloids and phenolics that probably play a role in the interaction between coffee and this leaf miner. The levels of chlorogenic and caffeic acid, caffeine, and related methylxanthines were measured and quantified in leaf extracts of these genotypes before and 7 d after their infestation by the leaf miner. Some coffee genotypes (Coffea canephora L. and Coffea racemosa Lour. and its hybrids with Coffea arabica L.) exhibited high pesticidal activity (100% mortality) toward the L. coffeella, indicating their antibiosis resistance. However, there was no correlation between this activity and the leaf levels of coffee alkaloids and phenolics. Curiously, infestation by L. coffeella leads to a nearly four-fold decline in the leaf levels of chlorogenic acid, which does not affect this pest species but may affect other generalist species. Indeed, chlorogenic acid sprayed on coffee leaves stimulated locomotory activity of the green scale Coccus viridis (Green) (Hemiptera: Coccidae), thus minimizing their feeding in contrast with the absence of this polyphenol. Therefore, reduction of chlorogenic acid levels in coffee leaves due to leaf miner infestation seems to also favor infestation by generalist insects, such as the green scale. PMID:20857759

Magalhes, S T V; Fernandes, F L; Demuner, A J; Picano, M C; Guedes, R N C

2010-08-01

355

The prediction of rice leaf's nitrogen content based on leaf spectrum on the heading stage  

Microsoft Academic Search

The change of crops' nitrogen content can cause the surface of crop leaf and the physiological characteristics of the internal organization to change, thus can cause the spectrum reflection characteristic of the crop leaf to change. In this paper, the amount of fertilizer was controlled, and nitrogen-containing samples of the rice cultivation experiment was conducted to study the relevant relations

Sun Jun; Lu Bing; Wu Xiaohong

2010-01-01

356

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

E-print Network

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

Goldberg, Bennett

357

In vitro response of leaf tissues from Lolium multiflorum a comparison with leaf segment position, leaf age and in vivo mitotic activity  

Microsoft Academic Search

Immature gramineous leaves provide a convenient system for comparing the response of cells in culture with their state of differentiation. Callusing frequency is compared with leaf segment position, leaf age and in vivo mitotic activity in Lolium multiflorum. (1) In a succession of one millimeter sections from the immature leaf base, callus was formed from the first and second sections

O. I. Joarder; N. H. Joarder; P. J. Dale

1986-01-01

358

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

PubMed

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

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

2013-10-01

359

Measurement of leaf relative water content by infrared reflectance  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

360

Leaf allometry of Salix viminalis during the first growing season.  

PubMed

We established linear and exponential relationships between leaf area (A) and leaf length (L), leaf width (W), W(2), L(2) and LW, in Salix viminalis L. Most relationships were significantly nonlinear, but good fits were obtained with both linear and exponential models. The nonlinear relationship between A and LW differed for leaves from sylleptic and proleptic shoots. Leaves from sylleptic and proleptic shoots also differed in specific leaf area (area/weight). Leaf shape (width/length ratio and position of maximum leaf width) changed with leaf size and differed for leaves from sylleptic and proleptic shoots. Leaf area could be modeled adequately using implicit shape descriptions. A good fit was obtained when the basal and distal parts of the leaf were described as a parabola and an ellipse, respectively. The average area of single leaves and specific leaf area increased both along vertical profiles within shoots and during the growing period. Our results (1) indicate that nonlinear models should be used to estimate leaf area from linear leaf dimensions for plant species with leaves that vary in shape with leaf size, and (2) demonstrate the dependence of leaf characteristics on both sampling date during the growing season and spatial position in the canopy. PMID:14871704

Verwijst, T; Wen, D Z

1996-07-01

361

BOREAS TE-9 NSA Leaf Chlorophyll Density  

NASA Technical Reports Server (NTRS)

The BOREAS TE-9 team collected several data sets related to chemical and photosynthetic properties of leaves in boreal forest tree species. These data were collected to help provide an explanation of potential seasonal and spatial changes of leaf pigment properties in boreal forest species at the NSA. At different dates (FFC-Winter, FFC-Thaw, IFC-1, IFC-2, and IMC-3), foliage samples were collected from the upper third of the canopy for five NSA sites (YJP, OJP, OBS, UBS, and OA) near Thompson, Manitoba. Subsamples of 100 needles for black spruce, 20 needles for jack pine, and single leaf for trembling aspen were cut into pieces and immersed in a 20-mL DMF aliquot in a Nalgene test tube. The extracted foliage materials were then oven-dried at 68 C for 48 hours and weighed. Extracted leaf dry weight was converted to a total leaf area basis to express the chlorophyll content in mg/sq cm of total leaf area. The data are provided in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Margolis, Hank; Sy, Mikailou

2000-01-01

362

Mueller matrix of a dicot leaf  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

363

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

PubMed Central

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

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

2011-01-01

364

Leaf-level nitrogen use efficiency: definition and importance.  

PubMed

Nitrogen use efficiency (NUE) has been widely used to study the relationship between nitrogen uptake and dry mass production in the plant. As a subsystem of plant nitrogen use efficiency (NUE), I have defined leaf-level NUE as the surplus production (gross production minus leaf respiration) per unit amount of nitrogen allocated to the leaf, with factorization into leaf nitrogen productivity (NP) and mean residence time of leaf nitrogen (MRT). These concepts were applied to two herbaceous stands: a perennial Solidago altissima stand and an annual Amaranthus patulus stand. S. altissima had more than three times higher leaf NUE than A. patulus due to nearly three times longer MRT of leaf N. In both species, NUE and NP were higher at the leaf level than at the plant level, because most leaf N is involved directly in the photosynthetic activity and because leaf surplus production is higher than the plant net production. MRT was longer at the plant level. The more than twice as long MRT at the plant level as at the leaf level in S. altissima was due to a large contribution of nitrogen storage belowground in the winter in this species. Thus, comparisons between a perennial and an annual system and between plant- and leaf-level NUE with their components revealed the importance of N allocation, storage, recycling, and turnover of organs for leaf photosynthetic production and plant dry mass growth. PMID:22179330

Hirose, Tadaki

2012-07-01

365

Explants of Ri-transformed hairy roots of spinach can develop embryogenic calli in the absence of gibberellic acid, an essential growth regulator for induction of embryogenesis from non-transformed roots  

Microsoft Academic Search

Hairy roots of spinach (Spinacia oleracea L.) were obtained by inoculation of cotyledon explants with wild-type Agrobacterium rhizogenes A13. Integration of the transfer DNA (T-DNA) of a root-inducing (Ri) plasmid of A. rhizogenes into the plant DNA was confirmed by the polymerase chain reaction. Somatic embryogenesis from explants of hairy roots were induced even when the callus-induction (CI) medium did

Takuma Ishizaki; Yoichiro Hoshino; Kiyoshi Masuda; Katsuji Oosawa

2002-01-01

366

Cloning of the amphibolic Calvin cycle/OPPP enzyme D-ribulose-5-phosphate 3-epimerase (EC 5.1.3.1) from spinach chloroplasts: functional and evolutionary aspects.  

PubMed

Exploiting the differential expression of genes for Calvin cycle enzymes in bundle-sheath and mesophyll cells of the C4 plant Sorghum bicolor L., we isolated via subtractive hybridization a molecular probe for the Calvin cycle enzyme D-ribulose-5-phosphate 3-epimerase (R5P3E)(EC 5.1.3.1), with the help of which several full-size cDNAs were isolated from spinach. Functional identity of the encoded mature subunit was shown by R5P3E activity found in affinity-purified glutatione S-transferase fusions expressed in Escherichia coli and by three-fold increase of R5P3E activity upon induction of E. coli overexpressing the spinach subunit under the control of the bacteriophage T7 promoter, demonstrating that we have cloned the first functional ribulose-5-phosphate 3-epimerase from any eukaryotic source. The chloroplast enzyme from spinach shares about 50% amino acid identity with its homologues from the Calvin cycle operons of the autotrophic purple bacteria Alcaligenes eutrophus and Rhodospirillum rubrum. A R5P3E-related eubacterial gene family was identified which arose through ancient duplications in prokaryotic chromosomes, three R5P3E-related genes of yet unknown function have persisted to the present within the E. coli genome. A gene phylogeny reveals that spinach R5P3E is more similar to eubacterial homologues than to the yeast sequence, suggesting a eubacterial origin for this plant nuclear gene. PMID:8616224

Nowitzki, U; Wyrich, R; Westhoff, P; Henze, K; Schnarrenberger, C; Martin, W

1995-12-01

367

9 CFR 319.702 - Lard, leaf lard.  

Code of Federal Regulations, 2012 CFR

...result in the adulteration or misbranding of the lard. The tissues shall be reasonably free from blood, and shall not include stomachs, livers, spleens, kidneys, and brains, or settlings and skimmings. Leaf Lard is lard prepared from fresh leaf...

2012-01-01

368

9 CFR 319.702 - Lard, leaf lard.  

Code of Federal Regulations, 2013 CFR

...result in the adulteration or misbranding of the lard. The tissues shall be reasonably free from blood, and shall not include stomachs, livers, spleens, kidneys, and brains, or settlings and skimmings. Leaf Lard is lard prepared from fresh leaf...

2013-01-01

369

7 CFR 51.1220 - Leaf or limb rub injury.  

Code of Federal Regulations, 2011 CFR

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

2011-01-01

370

7 CFR 51.1220 - Leaf or limb rub injury.  

Code of Federal Regulations, 2010 CFR

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

2010-01-01

371

DIGITAL IMAGE ANALYSIS OF ZOSTERA MARINA LEAF INJURY  

EPA Science Inventory

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

372

Microsoft PowerPoint - Leaf BRN09 POWERPOINT  

Cancer.gov

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

373

Effect of Light and NO3? on Wheat Leaf Phosphoenolpyruvate Carboxylase Activity  

PubMed Central

Phosphoenolpyruvate carboxylase (PEPcase) activity was studied in excised leaves of wheat (Triticum aestivum L.) in the dark and in the light, in presence of either N-free (low-NO3? leaves) or 40 millimolar KNO3 (high-NO3? leaves) nutrient solutions. PEPcase activity increased to 2.7-fold higher than that measured in dark-adapted tissue (control) during the first 60 minutes and continued to increase more slowly to 3.8-fold that of the control. This level was reached after 200 minutes exposure of the leaves to light and high NO3?. In contrast, the lower rate of increase recorded for low-NO3? leaves ceased after 60 minutes of exposure to light at 2.3-fold the control level. The short-term NO3? effect increased linearly with the level of NO3? uptake. In immunoprecipitation experiments, the antibody concentration for PEPcase precipitation increased with the protein extracts from the different treatments in the order: control, illuminated low-NO3? leaves, illuminated high-NO3? leaves. This order also applied with regard to a decreasing sensitivity to malate and an increasing stimulation by okadaic acid (an inhibitor of P-protein phosphatases). Following these studies, 32P labeling experiments were carried out in vivo. These showed that the light-induced change in the properties of the PEPcase was due to an alteration in the phosphorylation state of the protein and that this effect was enhanced in high-NO3? conditions. Based on the responses of PEPcase and sucrose phosphate synthase in wheat leaves to light and NO3?, an interpretation of the role of NO3? as either an inhibitor of P-protein phosphatase(s) or activator of protein kinase(s) is inferred. In the presence of NO3?, the phosphorylation state of both PEPcase and sucrose phosphate synthase is increased. This causes activation of the former enzyme and inhibition of the latter. We suggest that NO3? modulates the relative protein kinase/protein phosphatase ratio to favor increased phosphorylation of both enzymes in order to redirect carbon flow away from sucrose synthesis and toward amino acid synthesis. ImagesFigure 6 PMID:16668573

Le Van Quy; Foyer, Christine; Champigny, Marie-Louise

1991-01-01

374

From Individual Leaf Elongation to Whole Shoot Leaf Area Expansion: a Comparison of Three Aegilops and Two Triticum Species  

PubMed Central

Background and Aims Rapid leaf area expansion is a desirable trait in the early growth stages of cereal crops grown in low?rainfall areas. In this study, the traits associated with inherent variation in early leaf area expansion rates have been investigated in two wheat species (Triticum aestivum and T. durum) and three of its wild relatives (Aegilops umbellulata, A. caudata and A. tauschii) to find out whether the Aegilops species have a faster leaf area expansion in their early developmental stage than some of the current wheat species. Methods Growth of individual leaves, biomass allocation, and gas exchange were measured on hydroponically grown plants for 4 weeks. Key Results Leaf elongation rate (LER) was strongly and positively correlated with leaf width but not with leaf elongation duration (LED). The species with more rapidly elongating leaves showed a faster increase with leaf position in LER, leaf width and leaf area, higher relative leaf area expansion rates, and more biomass allocation to leaf sheaths and less to roots. No differences in leaf appearance rate were found amongst the species. Conclusions Aegilops tauschii was the only wild species with rapid leaf expansion rates similar to those of wheat, and it achieved the highest photosynthetic rates, making it an interesting species for further study. PMID:15155374

BULTYNCK, LIEVE; TER STEEGE, MARGREET W.; SCHORTEMEYER, MARCUS; POOT, PIETER; LAMBERS, HANS

2004-01-01

375

Pharmacognostic evaluation of Cayratia trifolia (Linn.) leaf  

PubMed Central

Objective To present a detailed pharmacognostic study of the leaf of Cayratia trifolia (C. trifolia) Linn. (Vitaceae), an important plant in the Indian system of medicine. Methods The macroscopy, microscopy, physiochemical analysis, preliminary testing, fluorescence analysis of powder of the plant and other WHO recommended methods for standardization were investigated. Results Leaves are trifoliolated with petioles (23 cm) long. Leaflets are ovate to oblong-ovate, (28 cm) long, (1.55 cm) wide, pointed at the tip. The leaf surface shows the anisocytic type stomata covered with guard cells followed by epidermis layer. Leaf surface contents including veins, vein islet and vein termination were also determined. Transverse section of leaf shows the epidermis layer followed by cuticle layer and vascular bandles (xylem and phloem). The mesophyll is differentiated into palisade and spongy parenchyma. Abundant covering trichomes emerge from the upper epidermis. Trichomes are uniseriate and multicellular. Strips of collenchyma are present below and upper layer of epidermis. Conclusions It can be concluded that the pharmacognostic profile of the C. trifolia is helpful in developing standards for quality, purity and sample identification. PMID:23569825

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

2012-01-01

376

Deferral of Leaf Senescence with Calcium 1  

PubMed Central

In view of the possibility that senescence may be a consequence of the deterioration of membrane compartments in the cells of leaves, calcium was studied as a possible agent which might defer senescence. The senescence of corn leaf discs was deferred by added calcium, and the effect was additive to the cytokinin deferral of senescence. Likewise, the senescence of Rumex leaf discs was deferred by added calcium, and the effect was additive to the gibberellin deferral of senescence. Detailed experiments with corn leaf discs established that the increase in apparent free space associated with senescence was completely prevented by calcium. An increase in hydraulic permeability during senescence was likewise demonstrated, and this increase was deferred by calcium; calcium plus benzyladenine was even more effective. Each of the measured functions of leaf senescence (chlorophyll content, protein decrease, apparent free space increase, and hydraulic permeability increase) was suppressed by calcium, and the interpretation is offered that the effects are a consequence of the calcium function in maintaining cellular membranes. PMID:16658538

Poovaiah, B. W.; Leopold, A. C.

1973-01-01

377

Variable depth recursion algorithm for leaf sequencing  

SciTech Connect

The processes of extraction and sweep are basic segmentation steps that are used in leaf sequencing algorithms. A modified version of a commercial leaf sequencer changed the way that the extracts are selected and expanded the search space, but the modification maintained the basic search paradigm of evaluating multiple solutions, each one consisting of up to 12 extracts and a sweep sequence. While it generated the best solutions compared to other published algorithms, it used more computation time. A new, faster algorithm selects one extract at a time but calls itself as an evaluation function a user-specified number of times, after which it uses the bidirectional sweeping window algorithm as the final evaluation function. To achieve a performance comparable to that of the modified commercial leaf sequencer, 2-3 calls were needed, and in all test cases, there were only slight improvements beyond two calls. For the 13 clinical test maps, computation speeds improved by a factor between 12 and 43, depending on the constraints, namely the ability to interdigitate and the avoidance of the tongue-and-groove under dose. The new algorithm was compared to the original and modified versions of the commercial leaf sequencer. It was also compared to other published algorithms for 1400, random, 15x15, test maps with 3-16 intensity levels. In every single case the new algorithm provided the best solution.

Siochi, R. Alfredo C. [Department of Radiation Oncology, University of Iowa, 200 Hawkins Street, Iowa City, Iowa 52240 (United States)

2007-02-15

378

Red Leaf Resources and the Commercialization of Oil Shale  

E-print Network

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

Utah, University of

379

7 CFR 28.517 - Leaf Grade No. 7.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Leaf Grade No. 7. 28.517 Section 28.517 Agriculture...Standards of the United States for the Leaf Grade of American Pima Cotton 28.517 Leaf Grade No. 7. American Pima cotton which in...

2010-01-01

380

Birch Leaf Miner STAN SWIER, Extension Specialist Emeritus, Entomology  

E-print Network

days the eggs hatch (1-20 per leaf). The young larvae mine between the lower and upper surfaces 2014 UNH EXTENSION PEST FACT SHEET 13 Food & Agriculture Introduction Leaf miner larvae David Capaert. Since birch leaf miner attacks may weaken the trees good fertility and horticultural care are needed

New Hampshire, University of

381

Phenotypic selection on leaf ecophysiological traits in Helianthus  

Microsoft Academic Search

Habitats that differ in soil resource availability are expected to differ for selection on resource-related plant traits. Here, we examined spatial and temporal variation in phenotypic selection on leaf ecophysiological traits for 10 Helianthus populations, including two species of hybrid origin, Helianthus anomalus and Helianthus deserticola, and artificial hybrids of their ancestral parents. Leaf traits assessed were leaf size, succulence,

L. A. Donovan; F. Ludwig; D. R. Rosenthal; L. H. Rieseberg; S. A. Dudley

2009-01-01

382

Mandatory Leaf Node Prediction in Hierarchical Multilabel Classification  

E-print Network

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

Kwok, James Tin-Yau

383

Turbine rotor-stator leaf seal and related method  

DOEpatents

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

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

2003-01-01

384

On the Relevance and Control of Leaf Angle  

Microsoft Academic Search

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

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

2010-01-01

385

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

Microsoft Academic Search

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

Janie S Brooks; Paul Feeny

2004-01-01

386

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

PubMed Central

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

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

2014-01-01

387

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

E-print Network

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

Barron-Gafford, Greg

388

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

Microsoft Academic Search

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

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

2011-01-01

389

Using Stream Leaf Packs to Explore Community Assembly  

NSDL National Science Digital Library

In this TIEE experiment, students will explore functional and taxonomic diversity in a stream ecosystem, learn about food web relationships, and learn about the ways in which abiotic and biotic factors determine what organisms are present in a community. Students will make and install artificial leaf packs in a stream, wait for the leaf packs to be colonized by stream organisms, measure abiotic variables that could influence leaf pack colonization, retrieve the leaf packs and classify the organisms they find in both taxonomic and functional ways, and participate in a class discussion of how the leaf pack community is situated within a larger ecosystem.

Hartley, Laurel

2011-08-29

390

Reversals of age-related declines in neuronal signal transduction, cognitive, and motor behavioral deficits with blueberry, spinach, or strawberry dietary supplementation.  

PubMed

Ample research indicates that age-related neuronal-behavioral decrements are the result of oxidative stress that may be ameliorated by antioxidants. Our previous study had shown that rats given dietary supplements of fruit and vegetable extracts with high antioxidant activity for 8 months beginning at 6 months of age retarded age-related declines in neuronal and cognitive function. The present study showed that such supplements (strawberry, spinach, or blueberry at 14.8, 9.1, or 18.6 gm of dried aqueous extract per kilogram of diet, respectively) fed for 8 weeks to 19-month-old Fischer 344 rats were also effective in reversing age-related deficits in several neuronal and behavioral parameters including: oxotremorine enhancement of K(+)-evoked release of dopamine from striatal slices, carbachol-stimulated GTPase activity, striatal Ca(45) buffering in striatal synaptosomes, motor behavioral performance on the rod walking and accelerod tasks, and Morris water maze performance. These findings suggest that, in addition to their known beneficial effects on cancer and heart disease, phytochemicals present in antioxidant-rich foods may be beneficial in reversing the course of neuronal and behavioral aging. PMID:10479711

Joseph, J A; Shukitt-Hale, B; Denisova, N A; Bielinski, D; Martin, A; McEwen, J J; Bickford, P C

1999-09-15

391

Kinetics of the flash-induced P515 response in relation to the H+-permeability of the membrane bound ATPase in spinach chloroplasts  

SciTech Connect

The effect of dicyclohexylcarbodiimide (DCCD) on the kinetics of the flash-induced P515 response and on the activity of the ATPase was investigated in isolated spinach chloroplasts. It was found that after the addition of 5 X 10(-8)mol DCCD the rate of ATP hydrolysis induced by a period of 60 sec illumination was decreased to less than 5% of its original value. At this concentration, hardly any effect, if at all, could be detected on the kinetics of the flash-induced P515 response, neither in dark-adapted nor in light-activated chloroplasts. It was concluded that the presence of concentrations of DCCD, sufficiently high to affect the ATPase activity, does not affect the kinetics of the flash-induced P515 response. Since DCCD decreases the H+ permeability of the membrane-bound ATPase, it was concluded that this permeability coefficient for protons is not an important factor in the regulation of the flash-induced membrane potential and, therefore, does not affect the kinetics of the flash-induced P515 response.

Peters, R.L.; van Kooten, O.; Vredenberg, W.J.

1985-08-01

392

Surgical reconstruction versus peripheral intervention in patients with critical limb ischemia - a prospective multicenter registry in Japan: The SPINACH study design and rationale.  

PubMed

Clinical evidence reflecting the recent development of treatments for patients with critical limb ischemia is mandatory to guide the decision-making process for the selection of revascularization procedures, including bypass or endovascular treatment. This paper describes the protocol for a clinical study that is designed and carried out by both vascular surgeons and interventional cardiologists collaboratively, and will investigate current treatment for critical limb ischemia in Japan. The registry aimed to recruit approximately 450 patients with critical limb ischemia, including approximately 150 patients who underwent bypass surgery and approximately 300 patients who underwent endovascular treatment in 23 institutions. The primary endpoint of this study is amputation-free survival at 36 months, and the secondary endpoints include major amputation, cardiovascular events, re-intervention, death, ulcer healing, and their composite outcomes. The SPINACH study aims to provide a suitable patient model for each revascularization procedure, bypass and endovascular treatment, and will expound on the role of each approach for critical limb ischemia treatment (Clinical trial registration UMIN000007050). PMID:24476584

Azuma, Nobuyoshi; Iida, Osamu; Takahara, Mitsuyoshi; Soga, Yoshimitsu; Kodama, Akio

2014-12-01

393

Identification and purification of a spinach chloroplast DNA-binding protein that interacts specifically with the plastid psaA-psaB-rps14 promoter region.  

PubMed

We have previously shown the presence in chloroplasts of sequence-specific DNA-binding proteins that interact specifically with two regions located downstream and upstream from the 5'-transcription start site of the plastid psaA-psaB-rps14 operon. As part of an effort to elucidate the regulatory mechanism of plastid transcription during plant development, we report here the purification and characterization of the chloroplast DNA-binding protein from spinach (Spinacia oleracea L. var. spinosa Ashers et Graeden) leaves that specifically recognizes sequences between positions +64 to +83 relative to the transcription start site. This DNA-binding protein has been highly purified from chloroplasts by using a combination of high-salt extraction, ammonium sulfate precipitation, heparin-agarose chromatography, and sequence-specific DNA-affinity chromatography. The protein exhibited an apparent molecular weight of 59-60 kDa on the basis of gel filtration. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Southwestern blot analysis further indicated that this DNA-binding protein is dimeric and composed of two approximately 31-kDa subunits. We discuss the properties of this protein in relation to the known chloroplast DNA-binding factors for plastid gene expression. PMID:9431684

Cheng, M C; Wu, S P; Chen, L F; Chen, S C

1997-01-01

394

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

PubMed

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

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

2014-01-01

395

Trypsin inhibitors from the garden four o'clock (Mirabilis jalapa) and spinach (Spinacia oleracea) seeds: isolation, characterization and chemical synthesis.  

PubMed

Five serine proteinase inhibitors (Mirabilis jalapa trypsin inhibitors, MJTI I and II and Spinacia oleracea trypsin inhibitors, SOTI I, II, and III) from the garden four-o'clock (M. jalapa) and spinach (S. oleracea) seeds were isolated. The purification procedures included affinity chromatography on immobilized methylchymotrypsin in the presence of 5M NaCl, ion exchange chromatography and/or preparative electrophoresis, and finally RP-HPLC on a C-18 column. The inhibitors, crosslinked by three disulfide bridges, are built of 35 to 37 amino-acid residues. Their primary structures differ from those of known trypsin inhibitors, but showed significant similarity to the antimicrobial peptides isolated from the seeds of M. jalapa (MJ-AMP1, MJ-AMP2), Mesembryanthemum crystallinum (AMP1), and Phytolacca americana (AMP-2 and PAFP-S) and from the hemolymph of Acrocinus longimanus (Alo-1, 2 and 3). The association equilibrium constants (K(a)) with bovine beta-trypsin for the inhibitors from M. jalapa (MJTI I and II) and S. oleracea (SOTI I-III) were found to be about 10(7)M(-1). Fully active MJTI I and SOTI I were obtained by solid-phase peptide synthesis. The disulfide bridge pattern in both inhibitors (Cys1-Cys4, Cys2-Cys5 and Cys3-Cys6) was established after their digestion with thermolysin and proteinase K followed by the MALDI-TOF analysis. PMID:17481678

Kowalska, Jolanta; Pszczo?a, Katarzyna; Wilimowska-Pelc, Anna; Lorenc-Kubis, Irena; Zuziak, Ewa; ?ugowski, Mateusz; ?egowska, Anna; Kwiatkowska, Anna; Sleszy?ska, Ma?gorzata; Lesner, Adam; Walewska, Aleksandra; Zab?otna, Ewa; Rolka, Krzysztof; Wilusz, Tadeusz

2007-06-01

396

Photoprotective Energy Dissipation Involves the Reorganization of Photosystem II Light-Harvesting Complexes in the Grana Membranes of Spinach Chloroplasts[W  

PubMed Central

Plants must regulate their use of absorbed light energy on a minute-by-minute basis to maximize the efficiency of photosynthesis and to protect photosystem II (PSII) reaction centers from photooxidative damage. The regulation of light harvesting involves the photoprotective dissipation of excess absorbed light energy in the light-harvesting antenna complexes (LHCs) as heat. Here, we report an investigation into the structural basis of light-harvesting regulation in intact spinach (Spinacia oleracea) chloroplasts using freeze-fracture electron microscopy, combined with laser confocal microscopy employing the fluorescence recovery after photobleaching technique. The results demonstrate that formation of the photoprotective state requires a structural reorganization of the photosynthetic membrane involving dissociation of LHCII from PSII and its aggregation. The structural changes are manifested by a reduced mobility of LHC antenna chlorophyll proteins. It is demonstrated that these changes occur rapidly and reversibly within 5 min of illumination and dark relaxation, are dependent on ?pH, and are enhanced by the deepoxidation of violaxanthin to zeaxanthin. PMID:21498680

Johnson, Matthew P.; Goral, Tomasz K.; Duffy, Christopher D.P.; Brain, Anthony P.R.; Mullineaux, Conrad W.; Ruban, Alexander V.

2011-01-01

397

Characterization of the secondary structure and thermostability of the extrinsic 16 kilodalton protein of spinach photosystem II by Fourier transform infrared spectroscopy  

NASA Astrophysics Data System (ADS)

The secondary structure and thermostability of the extrinsic 16 kDa protein of the spinach photosystem II (OEC16) were characterized in solution between 25 and 75C using Fourier transform infrared (FTIR) spectroscopy. Quantitative analyses of the amide I band (1700-1600 cm -1) showed that the OEC16 subunit contains 34% ?-helix, 28% ?-sheet, 6% turn, and 32% disorder structures at 25C. This structural feature differs significantly from that of OEC23 as we had reported previously (H. Zhang, Y. Ishikawa, Y. Yamamoto, R. Carpentier, FEBS Letters 426 (1998) 347-351), although both the OEC subunits are involved in regulating Ca 2+ and Cl - requirements. In addition, it was observed that the structure of OEC16 is stable at <60C. At increased temperatures, however, thermal denaturation due to an irreversible protein aggregation occurs with a conformational transition at ?65C. This transitional temperature is considerably higher than that (42.5C) of the PSII reaction centers as also determined by FTIR spectroscopy (J. De Las Rivas, J. Barber, Biochemistry 36 (1997) 8897-8903). The higher thermostability of OEC16 may indicate the role of OEC16 against heat inactivation of PSII in vivo.

Zhang, H.; Yamamoto, Y.; Ishikawa, Y.; Carpentier, R.

1999-12-01

398

Variations in the polarized leaf reflectance of Sorghum bicolor  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

399

BOREAS TE-5 Leaf Carbon Isotope Data  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

400

Peach Leaf Senescence Delayed by Criconemella xenoplax.  

PubMed

Fall annual leaf senescence of peach was delayed in the field and in microplots in the presence of Criconemella xenoplax. Soil from the rhizosphere of orchard trees with greener leaves had ca. 2.5 x more nematodes than soil around trees in a more advanced state of fall senescence. In microplots, monoclonal antibody enzyme immunoassay (EIA) of leaf cytokinins indicated that concentration of zeatin riboside-like substances and chlorophyll content were greater in leaves of trees growing in nematode-infested soil than in trees in uninfested soil. EIA also indicated the presence of substances resembling trans-zeatin, zeatin riboside, dihydrozeatin, and dihydrozeatin riboside-like substances in whole body homogenates of C. xenoplax. Levels of zeatin-like substances were present in the nematode in greater levels than the other related substances. PMID:19290258

Nyczepir, A P; Wood, B W

1988-10-01

401

BOREAS TE-5 Leaf Gas Exchange Data  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

402

Science Nation: Leaf-cutter Ants  

NSDL National Science Digital Library

In established colonies, millions of leaf-cutter ants cut and carry sections of leaves larger than their own bodies as part of a well choreographed, highly functioning society. With support from the National Science Foundation (NSF),bacteriologist Cameron Currie and his team study ants and their complex, productive societies to help address some of human society's most pressing challenges, such as better drugs and cleaner energy.

403

Changes in clonal poplar leaf chemistry caused by stem galls alter herbivory and leaf litter decomposition.  

PubMed

Gall-inducing insects are highly specialized herbivores that modify the phenotype of their host plants. Beyond the direct manipulation of plant morphology and physiology in the immediate environment of the gall, there is also evidence of plant-mediated effects of gall-inducing insects on other species of the assemblages and ecosystem processes associated with the host plant. We analysed the impact of gall infestation by the aphid Pemphigus spirothecae on chemical leaf traits of clonal Lombardy poplars (Populus nigra var. italica) and the subsequent effects on intensity of herbivory and decomposition of leaves across five sites. We measured the herbivory of two feeding guilds: leaf-chewing insects that feed on the blade (e.g. caterpillars and sawfly larvae) and skeletonising insects that feed on the mesophyll of the leaves (e.g. larvae of beetles). Galled leaves had higher phenol (35%) and lower nitrogen and cholorophyll contents (35% respectively 37%) than non-galled leaves, and these differences were stronger in August than in June. Total herbivory intensity was 27% higher on galled than on non-galled leaves; damage by leaf chewers was on average 61% higher on gall infested leaves, whereas damage by skeletonising insects was on average 39% higher on non-galled leaves. After nine months the decomposition rate of galled leaf litter was 15% lower than that of non-galled leaf litter presumably because of the lower nitrogen content of the galled leaf litter. This indicated after-life effects of gall infestation on the decomposers. We found no evidence for galling x environment interactions. PMID:24260333

Knkler, Nora; Brandl, Roland; Brndle, Martin

2013-01-01

404

Changes in Clonal Poplar Leaf Chemistry Caused by Stem Galls Alter Herbivory and Leaf Litter Decomposition  

PubMed Central

Gall-inducing insects are highly specialized herbivores that modify the phenotype of their host plants. Beyond the direct manipulation of plant morphology and physiology in the immediate environment of the gall, there is also evidence of plant-mediated effects of gall-inducing insects on other species of the assemblages and ecosystem processes associated with the host plant. We analysed the impact of gall infestation by the aphid Pemphigus spirothecae on chemical leaf traits of clonal Lombardy poplars (Populus nigra var. italica) and the subsequent effects on intensity of herbivory and decomposition of leaves across five sites. We measured the herbivory of two feeding guilds: leaf-chewing insects that feed on the blade (e.g. caterpillars and sawfly larvae) and skeletonising insects that feed on the mesophyll of the leaves (e.g. larvae of beetles). Galled leaves had higher phenol (35%) and lower nitrogen and cholorophyll contents (35% respectively 37%) than non-galled leaves, and these differences were stronger in August than in June. Total herbivory intensity was 27% higher on galled than on non-galled leaves; damage by leaf chewers was on average 61% higher on gall infested leaves, whereas damage by skeletonising insects was on average 39% higher on non-galled leaves. After nine months the decomposition rate of galled leaf litter was 15% lower than that of non-galled leaf litter presumably because of the lower nitrogen content of the galled leaf litter. This indicated after-life effects of gall infestation on the decomposers. We found no evidence for galling x environment interactions. PMID:24260333

Kunkler, Nora; Brandl, Roland; Brandle, Martin

2013-01-01

405

Analysis of the genome of the Escherichia coli O157:H7 2006 spinach-associated outbreak isolate indicates candidate genes that may enhance virulence.  

PubMed

In addition to causing diarrhea, Escherichia coli O157:H7 infection can lead to hemolytic-uremic syndrome (HUS), a severe disease characterized by hemolysis and renal failure. Differences in HUS frequency among E. coli O157:H7 outbreaks have been noted, but our understanding of bacterial factors that promote HUS is incomplete. In 2006, in an outbreak of E. coli O157:H7 caused by consumption of contaminated spinach, there was a notably high frequency of HUS. We sequenced the genome of the strain responsible (TW14359) with the goal of identifying candidate genetic factors that contribute to an enhanced ability to cause HUS. The TW14359 genome contains 70 kb of DNA segments not present in either of the two reference O157:H7 genomes. We identified seven putative virulence determinants, including two putative type III secretion system effector proteins, candidate genes that could result in increased pathogenicity or, alternatively, adaptation to plants, and an intact anaerobic nitric oxide reductase gene, norV. We surveyed 100 O157:H7 isolates for the presence of these putative virulence determinants. A norV deletion was found in over one-half of the strains surveyed and correlated strikingly with the absence of stx(1). The other putative virulence factors were found in 8 to 35% of the O157:H7 isolates surveyed, and their presence also correlated with the presence of norV and the absence of stx(1), indicating that the presence of norV may serve as a marker of a greater propensity for HUS, similar to the correlation between the absence of stx(1) and a propensity for HUS. PMID:19564389

Kulasekara, Bridget R; Jacobs, Michael; Zhou, Yang; Wu, Zaining; Sims, Elizabeth; Saenphimmachak, Channakhone; Rohmer, Laurence; Ritchie, Jennifer M; Radey, Matthew; McKevitt, Matthew; Freeman, Theodore Larson; Hayden, Hillary; Haugen, Eric; Gillett, Will; Fong, Christine; Chang, Jean; Beskhlebnaya, Viktoriya; Waldor, Matthew K; Samadpour, Mansour; Whittam, Thomas S; Kaul, Rajinder; Brittnacher, Mitchell; Miller, Samuel I

2009-09-01

406

The role of electron transport in determining the temperature dependence of the photosynthetic rate in spinach leaves grown at contrasting temperatures.  

PubMed

The temperature response of the uncoupled whole-chain electron transport rate (ETR) in thylakoid membranes differs depending on the growth temperature. However, the steps that limit whole-chain ETR are still unclear and the question of whether the temperature dependence of whole-chain ETR reflects that of the photosynthetic rate remains unresolved. Here, we determined the whole-chain, PSI and PSII ETR in thylakoid membranes isolated from spinach leaves grown at 30 degrees C [high temperature (HT)] and 15 degrees C [low temperature (LT)]. We measured temperature dependencies of the light-saturated photosynthetic rate at 360 microl l(-1) CO2 (A360) in HT and LT leaves. Both of the temperature dependences of whole-chain ETR and of A360 were different depending on the growth temperature. Whole-chain ETR was less than the rates of PSI ETR and PSII ETR in the broad temperature range, indicating that the process was limited by diffusion processes between the PSI and PSII. However, at high temperatures, whole-chain ETR appeared to be limited by not only the diffusion processes but also PSII ETR. The C3 photosynthesis model was used to evaluate the limitations of A360 by whole-chain ETR (Pr) and ribulose bisphosphate carboxylation (Pc). In HT leaves, A360 was co-limited by Pc and Pr at low temperatures, whereas at high temperatures, A360 was limited by Pc. On the other hand, in LT leaves, A360 was solely limited by Pc over the entire temperature range. The optimum temperature for A360 was determined by Pc in both HT and LT leaves. Thus, this study showed that, at low temperatures, the limiting step of A360 was different depending on the growth temperature, but was limited by Pc at high temperatures regardless of the growth temperatures. PMID:18296450

Yamori, Wataru; Noguchi, Ko; Kashino, Yasuhiro; Terashima, Ichiro

2008-04-01

407

/sup 15/N-Ammonia assimilation, 2-oxoglutarate transport, and glutamate export in spinach chloroplasts in the presence of dicarboxylates in the light  

SciTech Connect

The direct incorporation of /sup 15/NH/sub 4/Cl into amino acids in illuminated spinach (Spinacia oleracea L.) chloroplasts in the presence of 2-oxoglutarate plus malate was determined. The amido-N of glutamine was the most highly labeled N-atom during /sup 15/NH/sub 4/ assimilation in the presence of malate. In 4 minutes the /sup 15/N-label of the amido-N of glutamine was 37% enriched. In contrast, values obtained for both the N-atom of glutamate and the amino-N of glutamine were only about 20% while that of the N-atom of aspartate was only 3%. The addition of malate during the assimilation of /sup 15/NH/sub 4/Cl and Na/sup 15/NO/sub 2/ greatly increased the /sup 15/N-label into glutamine but did not qualitatively change the order of the incorporation of /sup 15/N-label into all the amino acids examined. This evidence indicates the direct involvement of the glutamine synthetase/glutamate synthase pathway for ammonia and nitrite assimilation in isolated chloroplasts. The addition of malate or succinate during ammonia assimilation also led to more than 3-fold increase in (/sup 14/C)2-oxoglutarate transport into the chloroplast as well as an increase in the export of (/sup 14/C)glutamate out of the chloroplast. Little (/sup 14/C)glutamine was detected in the medium of the chloroplast preparations. The stimulation of /sup 15/N-incorporation and (/sup 14/C)glutamate export by malate could be directly attributed to the increase in 2-oxoglutarate transport activity (via the 2-oxoglutarate translocator) observed in the presence of exogenous malate.

Woo, K.C.; Boyle, F.A.; Flugge, I.U.; Heldt, H.W.

1987-11-01

408

Estimation of stand-level leaf area for boreal bryophytes  

Microsoft Academic Search

Bryophytes dominate the carbon and nitrogen cycling of many poorly drained terrestrial ecosystems and are important in the\\u000a vegetation-atmosphere exchange of carbon and water, yet few studies have estimated their leaf area at the stand scale. This\\u000a study quantified the bryophyte-specific leaf area (SLA) and leaf area index (LAI) in a group of different-aged boreal forest\\u000a stands in well and

Ben Bond-Lamberty; Stith T. Gower

2007-01-01

409

Generality of leaf trait relationships: A test across six biomes  

SciTech Connect

Convergence in interspecific leaf trait relationships across diverse taxonomic groups and biomes would have important evolutionary and ecological implications. Such convergence has been hypothesized to result from trade-offs that limit the combination of plant traits for any species. Here the authors address this issue by testing for biome differences in the slope and intercept of interspecific relationships among leaf traits: longevity, net photosynthetic capacity (A{sub max}), leaf diffusive conductance (G{sub S}), specific leaf area (SLA), and nitrogen (N) status, for more than 100 species in six distinct biomes of the Americas. The six biomes were: alpine tundra-subalpine forest ecotone, cold temperate forest-prairie ecotone, montane cool temperate forest, desert shrubland, subtropical forest, and tropical rain forest. Despite large differences in climate and evolutionary history, in all biomes mass-based leaf N (N{sub mass}), SLA, G{sub S}, and A{sub max} were positively related to one another and decreased with increasing leaf life span. The relationships between pairs of leaf traits exhibited similar slopes among biomes, suggesting a predictable set of scaling relationships among key leaf morphological, chemical, and metabolic traits that are replicated globally among terrestrial ecosystems regardless of biome or vegetation type. However, the intercept (i.e., the overall elevation of regression lines) of relationships between pairs of leaf traits usually differed among biomes. With increasing aridity across sites, species had greater A{sub max} for a given level of G{sub S} and lower SLA for any given leaf life span. Using principal components analysis, most variation among species was explained by an axis related to mass-based leaf traits (A{sub max}, N, and SLA) while a second axis reflected climate, G{sub S}, and other area-based leaf traits.

Reich, P.B. [Univ. of Minnesota, Saint Paul, MN (United States). Dept. of Forest Resources; Ellsworth, D.S. [Brookhaven National Lab., Upton, NY (United States). Dept. of Applied Science; Walters, M.B. [Michigan State Univ., East Lansing, MI (United States). Dept. of Forestry; Vose, J.M. [Forest Service, Otto, NC (United States). Coweeta Hydrological Lab.; Gresham, C. [Clemson Univ., Georgetown, SC (United States). Baruch Forest Inst.; Volin, J.C. [Florida Atlantic Univ., Davie, FL (United States). Div. of Science; Bowman, W.D. [Inst. of Arctic and Alpine Research, Boulder, CO (United States). Mountain Research Station]|[Univ. of Colorado, Boulder, CO (United States). Dept. of Evolutionary, Population, and Organismic Biology

1999-09-01

410

Rapid biological synthesis of silver nanoparticles using plant leaf extracts  

Microsoft Academic Search

Five plant leaf extracts (Pine, Persimmon, Ginkgo, Magnolia and Platanus) were used and compared for their extracellular synthesis\\u000a of metallic silver nanoparticles. Stable silver nanoparticles were formed by treating aqueous solution of AgNO3 with the plant leaf extracts as reducing agent of Ag+ to Ag0. UV-visible spectroscopy was used to monitor the quantitative formation of silver nanoparticles. Magnolia leaf broth

Jae Yong Song; Beom Soo Kim

2009-01-01

411

Leaf life span of floating-leaved plants  

Microsoft Academic Search

Photosynthetic capacity of floating-leaved plants is relatively high comparable with terrestrial herbaceous plants, though floating-leaved plants have a much smaller biomass with a leaf area index seldom exceeding 2m2m-2. Their rather small biomass accumulation is related to higher turnover of leaf biomass or shorter leaf life span. Life span of floating leaves reported in the literature ranged mostly from 13

T. Tsuchiya

1991-01-01

412

A worldwide survey of tomato yellow leaf curl viruses  

Microsoft Academic Search

Summary.?The name tomato yellow leaf curl virus (TYLCV) has been given to several whitefly-transmitted geminiviruses affecting tomato\\u000a cultures in many tropical and subtropical regions. Hybridization tests with two DNA probes derived from a cloned isolate of\\u000a TYLCV from Israel (TYLCV-ISR) were used to assess the affinities of viruses in naturally infected tomato plants with yellow\\u000a leaf curl or leaf curl

H. Czosnek; H. Laterrot

1997-01-01

413

Leaf flavonoids of Galium sect. Aparinoides (Rubiaceae)  

Microsoft Academic Search

13 taxa belonging to 4 species groups ofGalium L. sect.Aparinoides (Jord.)Gren. produce 15 leaf flavonoids: Apigenin-7-diglucoside, Luteolin-7-monoglucoside and 7-diglucoside, Diosmetin, Diosmetin-7-monoglucoside and 7-diglucoside; Kaempferol-3-rutinoside, Kaempferol-3,7-diglucoside, Quercetin, two Quercetin-3-monoglycosides, Rutin, Quercetin-3-rutinoside-7-glucoside, Quercetin-7-glycoside and an unidentified aglycone. TheG. trifidum, G. obtusum andG. palustre groups (with the exception of theG. tinctorium subspecies andG. elongatum) have similar flavone-flavonole patterns, while theG. antarcticum group produces

Christian Puff

1975-01-01

414

Photocontrol of Sorghum Leaf Phosphoenolpyruvate Carboxylase 1  

PubMed Central

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

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

1987-01-01

415

Allelopathic potential of Rapanea umbellata leaf extracts.  

PubMed

The stressful conditions associated with the Brazilian savanna (Cerrado) environment were supposed to favor higher levels of allelochemicals in Rapanea umbellata from this ecosystem. The allelopathic potential of R. umbellata leaf extracts was studied using the etiolated wheat coleoptile and standard phytotoxicity bioassays. The most active extract was selected to perform a bioassay-guided isolation, which allowed identifying lutein (1) and (-)-catechin (2) as potential allelochemicals. Finally, the general bioactivity of the two compounds was studied, which indicated that the presence of 1 might be part of the defense mechanisms of this plant. PMID:23939802

Novaes, Paula; Imatomi, Maristela; Varela, Rosa M; Molinillo, Jos M G; Lacret, Rodney; Gualtieri, Sonia C J; Macas, Francisco A

2013-08-01

416

BOREAS TE-12 Leaf Gas Exchange Data  

NASA Technical Reports Server (NTRS)

The BOREAS TE-12 team collected several data sets in support of its efforts to characterize and interpret information on the reflectance, transmittance, and gas exchange of boreal vegetation. This data set contains measurements of leaf gas exchange conducted in the SSA during the growing seasons of 1994 and 1995 using a portable gas exchange system. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Center (DAAC).

Hall, Forrest G. (Editor); Curd, Shelaine (Editor); Arkebauer, Timothy J.; Yang, Litao

2000-01-01

417

Antibacterial activity of various leaf extracts of Merremia emarginata  

PubMed Central

Objective To investigate the antibacterial activity and phytochemical screening of the aqueous, methanol and petroleum ether leaf extracts of Merremia emarginata (M. emarginata). Methods The antibacterial activity of leaf extracts of M. emarginata were evaluated by agar well diffusion method against four selected bacterial species. Results The presence of tannins, flavonoids, amino acids, starch, glycosides and carbohydrates in the different leaf extracts was established. The methanol extract was more effective against Bacillus cereus and Escherichia coli, whereas aqueous extract was more effective against Staphylococcus aureus and Pseudomonas aeruginosa. Conclusions : The results in the present study suggest that M. emarginata leaf can be used in treating diseases caused by the tested organisms. PMID:23569802

Elumalai, EK; Ramachandran, M; Thirumalai, T; Vinothkumar, P

2011-01-01

418

Olive leaf extract inhibits lead poisoning-induced brain injury  

PubMed Central

Olive leaves have an antioxidant capacity, and olive leaf extract can protect the blood, spleen and hippocampus in lead-poisoned mice. However, little is known about the effects of olive leaf extract on lead-induced brain injury. This study was designed to determine whether olive leaf extract can inhibit lead-induced brain injury, and whether this effect is associated with antioxidant capacity. First, we established a mouse model of lead poisoning by continuous intragastric administration of lead acetate for 30 days. Two hours after successful model establishment, lead-poisoned mice were given olive leaf extract at doses of 250, 500 or 1 000 mg/kg daily by intragastric administration for 50 days. Under the transmission electron microscope, olive leaf extract attenuated neuronal and capillary injury and reduced damage to organelles and the matrix around the capillaries in the frontal lobe of the cerebral cortex in the lead-poisoned mice. Olive leaf extract at a dose of 1 000 mg/kg had the greatest protective effect. Spectrophotometry showed that olive leaf extract significantly increased the activities of superoxide dismutase, catalase, alkaline phosphatase and acid phosphatase, while it reduced malondialdehyde content, in a dose-dependent manner. Furthermore, immunohistochemical staining revealed that olive leaf extract dose-dependently decreased Bax protein expression in the cerebral cortex of lead-poisoned mice. Our findings indicate that olive leaf extract can inhibit lead-induced brain injury by increasing antioxidant capacity and reducing apoptosis. PMID:25206510

Wang, Yu; Wang, Shengqing; Cui, Wenhui; He, Jiujun; Wang, Zhenfu; Yang, Xiaolu

2013-01-01

419

The reflection and scattering of light by a plant leaf  

NASA Astrophysics Data System (ADS)

The spectral polarization characteristics of the visible radiation reflected and scattered by a plant leaf were investigated. Measurements of the spectral brightness coefficient, the directed reflection coefficients, and the degree and azimuth of polarization of radiation reflected from a leaf were performed at different angles of incidence of radiation on the leaf and different angles of observation. More than 500 measurements were performed for 36 samples. Maple (Acer platanoides) leaves from different trees were used as objects of investigation. Peculiarities of the mechanism of formation of the flux of radiation reflected from a plant leaf have been revealed.

Atrashevskii, Yu. I.; Sikorskii, A. V.; Sikorskii, V. V.; Stel'Makh, G. F.

1999-01-01

420

The effect of variety and maturity on the quality of freeze-dried carrots. The effect of microwave blanching on the nutritional and textural quality of freeze-dried spinach  

NASA Technical Reports Server (NTRS)

Using carrots, the quality of freeze-dried products was studied to determine the optimum varieties and maturation stages for quality attributes such as appearance, flavor, texture, and nutritive value. The quality of freeze-dried carrots is discussed in terms of Gardner color, alcohol insoluble solids, viscosity, and core/cortex ratio. Also, microwave blanching of freeze-dried spinach was studied to determine vitamin interrelationships, anatomical changes, and oxidative deteriorations in terms of preprocessing microwave treatments. Statistical methods were employed in the gathering of data and interpretation of results in both studies.

1979-01-01

421

Interspecfic variation in SO flux - leaf surface versus internal flux, and components of leaf conductance  

Microsoft Academic Search

The object of the study was to clarify the relationships among stomatal, residual, and epidermal conductances in determining the flux of SO air pollution to leaves. Variations in leaf SO and HO vapor fluxes were determined using four plant species: Pisum sativum L. (garden pea), Lycopersicon esculentum Mill. flacca (mutant of tomato), Geranium carolinianum L. (wild geranium), and Diplacus aurantiacus

D. M. Olszyk; D. T. Tingey

1985-01-01

422

Stomatal Closure during Leaf Dehydration, Correlation with Other Leaf Physiological Traits1  

E-print Network

) at ap- proximately the same time as the evolution of an internal water conducting system in plants desiccation remains controversial. This paper examines characteristics of the vascular and photosynthetic hydraulic conductance (Kleaf) was measured from the relaxation kinetics of leaf water potential ( l

Holbrook, N. Michele

423

INTERSPECFIC VARIATION IN SO2 FLUX - LEAF SURFACE 'VERSUS' INTERNAL FLUX, AND COMPONENTS OF LEAF CONDUCTANCE  

EPA Science Inventory

The object of the study was to clarify the relationships among stomatal, residual, and epidermal conductances in determining the flux of SO2 air pollution to leaves. Variations in leaf SO2 and H2O vapor fluxes were determined using four plant species: Pisum sativum L. (garden pea...

424

The Okra Leaf Shape Mutation in Cotton is Active in all Cell Layers of the Leaf  

Microsoft Academic Search

in the middle mesophyll of the lamina and the vasculature of major lateral veins (L3 derivatives) had no local effect on the expansion of the lamina, but significantly increased lobe length. These results demonstrate that L2 O is active in every tissue layer of the leaf.

Liam Dolan; R. Scott Poethig

1998-01-01

425

Digital measurement of heliotropic leaf response in soybean cultivars and leaf exposure to solar UVB radiation  

Microsoft Academic Search

Inconsistencies in reported sensitivities of soybean cultivars [Glycine max (L.) Merr.] to enhanced ultraviolet-B (UVB) irradiance may in part be due to differences in the radiative environment of the experimental conditions or differences in exposure due to heliotropic response. In order to examine the impact of heliotropic movement on UVB exposure of the soybean upper trifoliate, leaf position was electronically

Cheryl I Bawhey; Richard H Grant; Wei Gao

2003-01-01

426

Food selection by the South Indian leaf-monkey, Presbytis johnii , in relation to leaf chemistry  

Microsoft Academic Search

The leaf-monkey Presbytis johnii has been found to exhibit considerable selectivity in its dietary utilization of mature foliage in a rain-forest habitat. To investigate the basis of this selectivity and to examine the hypothesis that the observed selection is related to the digestibility and toxicity of the available foliage, chemical analyses have been made on 16 of the most important

John F. Oates; Peter G. Waterman; Gillian M. Choo

1980-01-01

427

Estimating leaf photosynthetic pigments information by stepwise multiple linear regression analysis and a leaf optical model  

NASA Astrophysics Data System (ADS)

Leaf pigments are key elements for plant photosynthesis and growth. Traditional manual sampling of these pigments is labor-intensive and costly, which also has the difficulty in capturing their temporal and spatial characteristics. The aim of this work is to estimate photosynthetic pigments at large scale by remote sensing. For this purpose, inverse model were proposed with the aid of stepwise multiple linear regression (SMLR) analysis. Furthermore, a leaf radiative transfer model (i.e. PROSPECT model) was employed to simulate the leaf reflectance where wavelength varies from 400 to 780 nm at 1 nm interval, and then these values were treated as the data from remote sensing observations. Meanwhile, simulated chlorophyll concentration (Cab), carotenoid concentration (Car) and their ratio (Cab/Car) were taken as target to build the regression model respectively. In this study, a total of 4000 samples were simulated via PROSPECT with different Cab, Car and leaf mesophyll structures as 70% of these samples were applied for training while the last 30% for model validation. Reflectance (r) and its mathematic transformations (1/r and log (1/r)) were all employed to build regression model respectively. Results showed fair agreements between pigments and simulated reflectance with all adjusted coefficients of determination (R2) larger than 0.8 as 6 wavebands were selected to build the SMLR model. The largest value of R2 for Cab, Car and Cab/Car are 0.8845, 0.876 and 0.8765, respectively. Meanwhile, mathematic transformations of reflectance showed little influence on regression accuracy. We concluded that it was feasible to estimate the chlorophyll and carotenoids and their ratio based on statistical model with leaf reflectance data.

Liu, Pudong; Shi, Runhe; Wang, Hong; Bai, Kaixu; Gao, Wei

2014-10-01

428

On the temporal variation of leaf magnetic parameters: seasonal accumulation of leaf-deposited and leaf-encapsulated particles of a roadside tree crown.  

PubMed

Understanding the accumulation behaviour of atmospheric particles inside tree leaves is of great importance for the interpretation of biomagnetic monitoring results. In this study, we evaluated the temporal variation of the saturation isothermal remanent magnetisation (SIRM) of leaves of a roadside urban Platanus acerifolia Willd. tree in Antwerp, Belgium. We hereby examined the seasonal development of the total leaf SIRM signal as well as the leaf-encapsulated fraction of the deposited dust, by washing the leaves before biomagnetic analysis. On average 38% of the leaf SIRM signal was exhibited by the leaf-encapsulated particles. Significant correlations were found between the SIRM and the cumulative daily average atmospheric PM10 and PM2.5 measurements. Moreover, a steady increase of the SIRM throughout the in-leaf season was observed endorsing the applicability of biomagnetic monitoring as a proxy for the time-integrated PM exposure of urban tree leaves. Strongest correlations were obtained for the SIRM of the leaf-encapsulated particles which confirms the dynamic nature of the leaf surface-accumulated particles. PMID:25000572

Hofman, Jelle; Wuyts, Karen; Van Wittenberghe, Shari; Samson, Roeland

2014-09-15

429

Pharmacognostical evaluation of Barringtonia acutangula leaf  

PubMed Central

Barringtonia acutangula (L.) Gaertn. (Family: Lecythidaceae) is an evergreen tree with simple, alternate leaves, long pendulous racemes, dark scarlet flowers, and ellipsoid to ovoid berries containing one ovoid black seed. The present study deals with a detailed pharmacognostical study on the leaf of the crude drug, B. acutangula. Morphoanatomy of the leaf was studied using light and confocal microscopy and World Health Organization (WHO) guidelines on quality control methods for medicinal plant materials. Literature reveals that the phytoconstituents like tanginol, barrinic acid, and barringenic acid are present in the wood and fruits of this plant. Our preliminary phytochemical studies of the powdered leaves revealed the presence of terpenes, flavanoids, carbohydrates, tannins, steroids, and glycosides. The physico-chemical, morphological, histological parameters, and High Performance-Thin Layer Chromatographic (HPTLC) profile presented in this paper may be proposed as parameters to establish the authenticity of B. acutangula and can possibly help to differentiate the drug from its other species and the pharmacognostic profile of the leaves presented here will assist in standardization viz., quality, purity, and sample identification. PMID:21897641

Padmavathi, Dharamaraj; Susheela, Lakshmi; Bharathi, Rajkishore Vijaya

2011-01-01

430

Leaf metallome preserved over 50 million years.  

PubMed

Large-scale Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) elemental mapping and X-ray absorption spectroscopy are applied here to fossil leaf material from the 50 Mya Green River Formation (USA) in order to improve our understanding of the chemistry of fossilized plant remains. SRS-XRF of fossilized animals has previously shown that bioaccumulated trace metals and sulfur compounds may be preserved in their original distributions and these elements can also act as biomarkers for specific biosynthetic pathways. Similar spatially resolved chemical data for fossilized plants is sparsely represented in the literature despite the multitude of other chemical studies performed. Here, synchrotron data from multiple specimens consistently show that fossil leaves possess chemical inventories consisting of organometallic and organosulfur compounds that: (1) map discretely within the fossils, (2) resolve fine scale biological structures, and (3) are distinct from embedding sedimentary matrices. Additionally, the chemical distributions in fossil leaves are directly comparable to those of extant leaves. This evidence strongly suggests that a significant fraction of the chemical inventory of the examined fossil leaf material is derived from the living organisms and that original bioaccumulated elements have been preserved in situ for 50 million years. Chemical information of this kind has so far been unknown for fossilized plants and could for the first time allow the metallome of extinct flora to be studied. PMID:24804302

Edwards, N P; Manning, P L; Bergmann, U; Larson, P L; van Dongen, B E; Sellers, W I; Webb, S M; Sokaras, D; Alonso-Mori, R; Ignatyev, K; Barden, H E; van Veelen, A; Ann, J; Egerton, V M; Wogelius, R A

2014-04-01

431

Protein changes during oat leaf senescence  

SciTech Connect

Protein changes during in situ and in vitro senescence of the first leaf of 8-day old seedlings of Avena sativa cv. Victory have been examined. Senescence was induced by placing either intact seedlings or by floating the apical 3 cm-long leaf segments on water, in dark at 27 C for 0 to 4 days. Total protein content and chlorophyll content declined steadily during senescence. Rate of amino acid uptake, studied with /sup 14/C-B-alanine, declined sharply. Rate of protein synthesis decreased during the first 24 h during in vitro, and 48 h during in situ senescence. Thereafter, the rate increased sharply. At the end of 4 days the rate of protein synthesis had again declined in case of in vitro senescence but remained high in case of in situ senescence. Large changes in protein patterns, as shown by 1-D and 2-D PAGE, also occurred during senescence. Major changes in the population of translatable mRNAs that occur during in situ and in vitro senescence will be compared and discussed.

Dhindsa, R.S.; Tsai, C.D.; Lalonde, L.

1986-04-01

432

Spectroscopic determination of leaf nutritional, morpholgical, and metabolic traits  

NASA Astrophysics Data System (ADS)

Terrestrial ecosystems, particularly forests, play an important role in the global carbon and water cycles. Remote sensing observations are invaluable to the study of vegetation patterning, ecosystem functioning, and dynamics. This research examined the relationships between leaf optical properties and important leaf structural, biochemical, and metabolic traits that describe the photosynthetic capacity, recalcitrance, and nutrient dynamics of plant canopies. This was done utilizing leaf-level reflectance spectroscopy in conjunction with traditional chemometric statistical techniques designed to handle high-dimensionality data, specifically partial least-squares regression (PLSR). A suite of leaf biochemical and morphological traits were estimated with high accuracy and precision using measurements of dried and ground leaf material with a portable spectroradiometer in conjunction with PLSR modeling. An important result from this study was that a single model could be developed to accurately estimate the variation in leaf traits, including nitrogen and carbon content, lignin, fiber and cellulose, isotopic nitrogen-15, and leaf mass per area, across species, growth environments, throughout the vertical profile of a canopy, and with leaf lifespan. A residual analysis of the model prediction errors showed no significant biases observed by tree species, canopy position, or leaf age. Fresh-leaf reflectance spectroscopy was used to identify the linkages between leaf photosynthetic metabolism and leaf optical properties within controlled and natural environments, and across diverse plant species. Two key parameters controlling photosynthetic rates - the maximum rates of RuBisCO carboxylation (Vcmax) and RuBP regeneration ( Jmax) --- were directly estimated using leaf spectra and concurrent gas-exchange measurements. The models for each variable captured the pronounced temperature sensitivity of plants, and integrated the significant variability in metabolism across species that is related to differences in leaf structure and biochemistry. The PLSR models displayed high accuracy in predictions using independent validation data. Models identified key spectral regions related to leaf biochemistry, including foliar nitrogen and pigments, as well as wavelengths related to the regulation of photosynthesis, dissipation of excess energy and chlorophyll fluorescence. In sum, this research provides a novel empirical basis for estimating parameters critical to the measurement of photosynthetic activity in plants.

Serbin, Shawn P.

433

Temperature response of whole-plant CO2 exchange rates of four upland cotton cultivars differing in leaf shape and leaf pubescence  

Microsoft Academic Search

It seems likely that CO2 exchange rates of cotton (Gossypium hirsutum L.) cultivars differing in leaf shape and leaf pubescence would respond differently to heat stress due to differences in boundary layer thickness. The objective of this study was to determine if CO2 exchange rates in commercially available cotton cultivars differing in leaf shape and leaf pubescence respond differently to

Craig W. Bednarz; Marc W. van Iersel

2001-01-01

434

Survey on Modeling and Visualization of Plant Leaf Color  

Microsoft Academic Search

Much work has been done on the morphologic modeling and visualization of leaves. Leaf is one of the most important organs of a plant, and so leaf color and texture are not only important external characteristics, but also expressions of the plant's intrinsic physiology and the growth state, since they have a close relationship with the physiological status. Growth, age,

Xiaomin Wang; Chunjiang Zhao; Shenglian Lu; Xinyu Guo

2009-01-01

435

Tamarindus indica L. leaf is a source of allelopathic substance  

Microsoft Academic Search

The allelopathic potential of the Tamarindus indica L. leaf was investigated through bioassay guided studies using several weed and edible crop species. Both radicle and hypocotyl growth of all the plant species tested was strongly inhibited by the tamarind leaf using a sandwich method. The growth of weed species was reduced more than that of edible crop species. Among the

Syeda Shahnaz Parvez; Mohammad Masud Parvez; Eiji Nishihara; Hiroshi Gemma; Yoshiharu Fujii

2003-01-01

436

The biochemical control of leaf expansion during drought  

Microsoft Academic Search

Over the past decade it has become clear that we cannot always explain the observed reduction in leaf expansion rates during drought by measuring the plant's water relations. This has led us to question the possibility of a role for the cell wall and its biochemical machinery in controlling the rate of leaf expansion during drought. However, if we are

Mark A. Bacon

1999-01-01

437

RESEARCH PAPER The dependence of leaf hydraulic conductance on  

E-print Network

of the leaf vascular system, extravascular tissues and stomates in an approxi- mately serial pathway. Leaf hydraulic conductance to liquid water (KL) on irradiance when measured with a high pressure flowmeter (HPFM). During HPFM measurements, water is perfused into leaves faster than it evaporates hence water infiltrates

Sack, Lawren