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Artykuły w czasopismach na temat "Ethylene Systems"
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Zemlyanskaya, Elena V., Nadya A. Omelyanchuk, Elena V. Ubogoeva i Victoria V. Mironova. "Deciphering Auxin-Ethylene Crosstalk at a Systems Level". International Journal of Molecular Sciences 19, nr 12 (14.12.2018): 4060. http://dx.doi.org/10.3390/ijms19124060.
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The auxin and ethylene pathways cooperatively regulate a variety of developmental processes in plants. Growth responses to ethylene are largely dependent on auxin, the key regulator of plant morphogenesis. Auxin, in turn, is capable of inducing ethylene biosynthesis and signaling, making the interaction of these hormones reciprocal. Recent studies discovered a number of molecular events underlying auxin-ethylene crosstalk. In this review, we summarize the results of fine-scale and large-scale experiments on the interactions between the auxin and ethylene pathways in Arabidopsis. We integrate knowledge on molecular crosstalk events, their tissue specificity, and associated phenotypic responses to decipher the crosstalk mechanisms at a systems level. We also discuss the prospects of applying systems biology approaches to study the mechanisms of crosstalk between plant hormones.
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Gubrium, E. K., D. G. Clark, H. J. Klee, T. A. Nell i J. E. Barrett. "Analysis of Horticultural Performance of Ethylene-insensitive Petunias and Tomatoes". HortScience 32, nr 3 (czerwiec 1997): 499D—499. http://dx.doi.org/10.21273/hortsci.32.3.499d.
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We are studying the horticultural performance of two model plant systems that carry a mutant gene that confers ethylene-insensitivity: Never Ripe tomatoes and petunia plants transformed with the mutant etr1-1 gene isolated from Arabidopsis thaliana. Having two model systems to compare side-by-side allows us to determine with greater certainty ethylene's role at different developmental stages. Presence of the mutant etr1-1 gene in transgenic petunias was determined using three techniques: PCR analysis, the seedling triple response assay (inhibition of stem elongation, radial swelling of stem and roots, and an exaggerated apical hook when grown in the dark and in the presence of ethylene), and the flower wilting response to pollination, which is known to be induced by ethylene. Flowers from ethylene-insensitive petunias took almost four times as long to wilt after pollination as wild-type plants. It is well known that fruit ripening in Never Ripe tomato is inhibited, and a similar delayed fruit ripening phenotype is observed in petunia plants transformed with etr1-1. In an effort to maintain ethylene-insensitive petunia plants by vegetative propagation, we observed that the rate of adventitious root formation was much lower with transgenic plants than in wild-type plants. In subsequent experiments on adventitious root formation in Never Ripe tomato, we observed the same result. Therefore, while ethylene-insensitive tomato and petunia plants appear phenotypically normal for many characters, other factors are altered by the presence of this mutation. The fact that these changes are present in two model systems helps to define the role of ethylene perception in plant growth and reproduction.
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Faingol'd, E. E., S. L. Saratovskikh, A. N. Panin, O. N. Babkina, I. V. Zharkov, N. O. Garifullin, G. V. Shilov i N. M. Bravaya. "Ethylene/propylene and ethylene/propylene/5-ethylidene-2-norbornene copolymerizations on metallocene/(2,6-tBu2PhO-)AliBu2 catalyst systems". Polymer 220 (kwiecień 2021): 123559. http://dx.doi.org/10.1016/j.polymer.2021.123559.
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Samuel, T., i G. S. Laddha. "The ternary systems with ethylene glycol". Journal of Applied Chemistry 9, nr 4 (4.05.2007): 246–48. http://dx.doi.org/10.1002/jctb.5010090409.
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Hernández, Luis González, Andrés Rodríguez Díaz i Juan Luis de Benito González. "Different Curing Systems for Ethylene-Propylene Elastomers". Rubber Chemistry and Technology 65, nr 5 (1.11.1992): 869–78. http://dx.doi.org/10.5254/1.3538647.
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Abstract The scope of this paper is to review peroxide curing of ethylene-propylene elastomers, where apart from crosslinking, other reactions occur, such as chain scission, which account for the drop in physical properties. The results are compared with an alternative crosslinking system which is being assessed in our laboratory. With the new curing agent the chain-scission reaction is not present and the physical properties of the vulcanizates are improved. The effects of the different crosslinking systems on the reaction transitions are studied with the aid of dynamic mechanical analysis.
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Hammouda, B., D. Ho i S. Kline. "SANS from Poly(ethylene oxide)/Water Systems". Macromolecules 35, nr 22 (październik 2002): 8578–85. http://dx.doi.org/10.1021/ma011657n.
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GRAY, F., J. MACCALLUM i C. VINCENT. "Poly(ethylene oxide) - LiCF3SO3 - polystyrene electrolyte systems". Solid State Ionics 18-19 (styczeń 1986): 282–86. http://dx.doi.org/10.1016/0167-2738(86)90127-x.
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Xiao, Min, i Margaret W. Frey. "Study of cellulose/ethylene diamine/salt systems". Cellulose 16, nr 3 (28.02.2009): 381–91. http://dx.doi.org/10.1007/s10570-009-9284-2.
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Bogdanov, B., i M. Mihailov. "Melting of water/poly(ethylene oxide) systems". Journal of Polymer Science: Polymer Physics Edition 23, nr 10 (październik 1985): 2149–58. http://dx.doi.org/10.1002/pol.1985.180231011.
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Michiels, Wilfried, i Antonio Muñoz-Escalona. "Mixed cocatalyst systems in metallocene ethylene polymerization". Macromolecular Symposia 97, nr 1 (lipiec 1995): 171–83. http://dx.doi.org/10.1002/masy.19950970118.
Pełny tekst źródłaRozprawy doktorskie na temat "Ethylene Systems"
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Mastroianni, Sergio. "New catalytic systems for the polymerisation of ethylene". Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343906.
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Iemsam-Arng, J. "Poly(ethylene) glycol based delivery systems for nucleic acid therapies". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1381001/.
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Our work is aimed at developing a synthetic biocompatible gene and siRNA delivery system for the treatment of primary and metastatic tumours. To facilitate delivery of nucleic acid based drugs into the cell, one strategy is to formulate the naked gene with an amine based non-viral gene delivery system via the counterion interaction. The delivery systems including 4arm-PEG-amine, 4arm-PEG-N-2-ethylamine, 8arm-PEG-amine and 8arm-PEG-N-2-ethylamine were synthesised, characterised and complexed with a reporter gene (β-gal plasmid DNA) in phosphate buffer pH 6.0. The resulting complexes were sized and their zeta potential measured (Malvern Zetasizer 3000HS, Malvern Instruments, UK). The complexes were also imaged using transmission electron microscopy and characterised for DNA binding and DNA protection using gel electrophoresis and the ethidium bromide displacement assay. The in vitro transfection efficiency and cell cytotoxicity of the complexes were determined in the A431 and HeLa cells. Additionally, in vivo therapeutic studies in female nude tumour bearing mice were carried out. A promising DNA-polymer complex of 4arm-PEG-N-2-ethylamine produced a complex of 200-300 nm in diameter (polydispersity < 0.6). Complexes had a zeta potential of +19.8 mV (n=3) and were spherical, fibrillar and toroidal in shape. The new gene delivery complex protected DNA from degradation in serum up to 2 hours and was as efficient as poly(ethylenimine) (PEI) in transfecting the A431 cell line, but it was more than 3 orders of magnitude less cytotoxic than PEI. In vivo a gene medicine, comprising the polymer and the tumour necrosis factor alpha gene, was tumouricidal. When complexed with siRNA, the siRNA polymer complex demonstrated a trend of gene silencing activity. A new synthetic gene delivery polymer of 4arm-PEG-N-2-ethylamine has been synthesised. This polymer is biocompatible to cells and is an efficient in vitro and in vivo gene transfer agent.
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Cheung, Adolf S. F. "Phase behavior of two binary systems containing ethylene at supercritical conditions". Thesis, University of Ottawa (Canada), 1989. http://hdl.handle.net/10393/5719.
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Beigzadeh, Daryoosh. "Long-chain branching in ethylene polymerization using combined metallocene catalyst systems". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/NQ52024.pdf.
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Anantharaman, Bharthwaj. "Reaction mechanisms for catalytic partial oxidation systems : application to ethylene epoxidation". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32328.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2005.Includes bibliographical references.
With the rapid advances in kinetic modeling, building elementary surface mechanisms have become vital to understand the complex chemistry for catalytic partial oxidation systems. Given that there is selected experimental knowledge on surface species and a large number of unknown thermochemical, rate parameters, the challenge is to integrate the knowledge to identify all the important species and accurately estimate the parameters to build a detailed surface mechanism. This thesis presents computational methodology for quickly calculating thermodynamically consistent temperature/coverage-dependent heats of formation, heat capacities and entropies, correction approach for improving accuracy in heats of formation predicted by composite G3- based quantum chemistry methods, and detailed surface mechanism for explaining selectivity in ethylene epoxidation. Basis of the computational methodology is the Unity Bond Index- Quadratic Exponential Potential (UBI-QEP) approach, which applies quadratic exponential potential to model interaction energies between atoms and additive pairwise energies to compute total energy of an adsorbed molecule. By minimizing the total energy subject to bond order constraint, formulas for chemisorption enthalpies have been derived for surface species bound to on-top, hollow and bridge coordination sites with symmetric, asymmetric and chelating coordination structures on transition metal catalysts. The UBI-QEP theory for diatomics has been extended for polyatomic adsorbates with empirical modifications to the theory.
(cont.) Formulas for activation energies have been derived for generic reaction types, including simple adsorption, dissociation-recombination, and disproportionation reactions. Basis of the correction approach is the Bond Additivity Correction (BAC) procedures, which apply atomic, molecular and bond- wise modifications to enthalpies of molecules predicted by G3B3 and G3MP2B3 composite quantum chemistry methods available in Gaussian® suite of programs. The new procedures have improved the accuracy of thermochemical properties for open and closed shell molecules containing various chemical moieties, multireference configurations, isomers and degrees of saturation involving elements from first 3 rows of the periodic table. The detailed mechanism explains the selectivity to ethylene oxide based on the parallel branching reactions of surface oxametallacycle to epoxide and acetaldehyde. Using Decomposition Tree Approach, surface reactions and species have been generated to develop a comprehensive mechanism for epoxidation. As a result of these developments in the thesis, chemisorption enthalpies can now be estimated within 3 kcal/mol of experimental values for transition metal catalysts and enthalpies predicted by G3B3 and G3MP2B3 Gaussian methods can be corrected within 0.5 kcal/mol. Examples of heterogeneous reaction systems involving silver-catalyzed ethylene epoxidation demonstrate the effectiveness of the methodologies developed in this work.
by Bharthwaj Anantharaman.
Ph.D.
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Polverari, Marco. "Dynamic and evanescent wave light scattering of poly(ethylene oxide) - latex systems". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28515.
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The principal aims of the thesis were to carry out a systematic analytical study to determine the solution properties of narrow-distribution and broad-distribution linear poly(ethylene oxide) (PEO) polymer samples in aqueous and organic solution and to study the adsorption properties of these polymer samples onto glass interfaces and spherical latex particles. The deposition characteristics of various types of bare and PEO coated latex particles onto collector surfaces were also studied.These studies allowed to ascertain the presence of PEO clusters in aqueous solution. The cluster size was found to be time dependent and to vary between 0.45 $ mu$m and 0.90 $ mu$m. The clusters were found to be in a thermodynamic equilibrium with the free polymer in solution and were found to reform spontaneously after a 30 minute period following filtration.
Adsorption studies indicated that the adsorption of PEO onto latex particles is kinetically controlled and that increased surface roughness and polarity of the latex particles decreases PEO adsorption. PEO clusters in solution were found to increase the value of the effective diffusion constant, D$ rm sb{eff}$ and thus decrease the calculated hydrodynamic layer thickness.
Evanescent wave light scattering was used in conjunction with a hydrodynamic impinging jet method for the study of depositing and non-depositing colloidal systems near interfaces. For non-depositing systems a comparison of the measured particle concentration profiles to the theoretically expected particle concentration profiles, calculated from DLVO theory, was made. The agreement was found to be very good.
The deposition of bare and PEO-coated latex particles onto glass interfaces was also investigated. From the data it was found that bare and smooth latex particles adsorb much more strongly onto collector surfaces than "hairy" latex particles which have long copolymer chains, such as itachonic acid, grafted onto their surfaces. The results indicated that the thicker the adsorbed polymer layer, the stronger the steric force preventing deposition of the polymer coated colloidal particles onto the collector surface. When the combined ellipsometric layer thickness of the particles and the collector surface exceeded a critical value, found to be about 15 nm, no particle deposition onto the collector surface was possible.
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Nacerodien, Mogamat Thaabit. "Investigation of polymer grade blending in Ziegler-Natta Catalysed ethylene polymerisation systems". Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9122.
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Includes bibliographical references.Polyethylene is one of the most widely used polymers to date and it is an important commodity in a variety of fields. Most existing polyethylene plants operate on technology involving heterogeneous Ziegler-Natta catalysts. Plants often change operating conditions to produce different polymer grades; this allows them to cater to a larger polymer market. A side-effect of this practice is the unwanted formation of off-spec polymer during the grade transition periods. Numerous studies have been conducted to address the issue of off-spec polymer formation. These studies involve applying optimal control theory to minimise the grade transition time or to minimise the amount of off-spec polymer generated during the transient period. This field of study is known as grade transition optimisation. The current study aims to provide an alternative approach to addressing the problem of offspec accumulation. It is proposed that stored off-spec polymer is blended with virgin polymer to provide a saleable and desirable product. The approach might be different, but the same techniques used in grade transition optimisation are applied. Polyethylene produced using Ziegler-Natta catalysts have relatively linear chains, thus a chain length distribution coefficient is sufficient to characterise the polymer product. The number average chain length and polydispersity index are adequate representatives of this distribution for reporting the properties of a polyethylene grade. For the purpose of applying optimal control theory, a polyethylene production process model was developed to calculate these average properties using a kinetic scheme based on fundamental principles. This process model is able to predict the polymer properties under both steady-state and unsteady-state behaviour. A key feature of the model is its ability to solve the system with low computational expense due to the use of the segregation approach to link particle properties to the overall bulk phase. This is especially useful since optimisation algorithms used in optimal control theory are iterative by nature. The Differential Evolution Algorithm (DEA) was used to minimise the objective functions that were developed for the optimisation schemes due to its ability to evaluate objective functions in parallel. A model of the blending aspect of the process was developed where it was derived that the polymer moments are additive on a mass basis. Pure grades were blended in a laboratory in various mass ratios and analysed using GPC to determine their molecular weight distribution curves. It was found that the model-predicted curves and the experimentally-determined curves were an excellent match, thus validating the model. In the current study, three procedures for blending off-spec material under standard industry conditions are proposed. The first method involves the introduction of off-spec polymer on a continuous basis to the virgin polymer stream during steady-state operation.
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Radcliffe, James Edward. "Discovery and development of novel P,N ligands for selective ethylene oligomerisation systems". Thesis, Durham University, 2015. http://etheses.dur.ac.uk/11301/.
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This thesis documents the design, discovery, and development of a range of P,N-type ligands and their application in selective ethylene oligomerisation processes. Two classes of ligand have been investigated, PNE (Ph2P(CH2)2NC4H8E, E = NMe, O, CH2) ligands, and iminophosphine ligands (R(PR’2)C=NAr). The coordination chemistry of both these series of compounds has been investigated with various chromium species, and the behaviour of these molecules in ethylene oligomerisation systems probed. Chapter 2 explores the application of PNE ligands to ethylene oligomerisation. The coordination chemistry of the PNE ligands with a selection of group VI starting materials has been investigated. It has been shown that both the PNO and PNC ligands form bidentate complexes upon reaction with CrCl3(THF)3 (e.g. CrCl3(THF)(PNO), 2.1), while attempts to synthesise the PNN analogue proved unsuccessful. The coordination of PNE ligands with Cr(0) and Mo(0) has been studied, with the ligands exhibiting both mono- (e.g. Cr(CO)5(PNN) (2.4) and bi-dentate coordination (e.g. Mo(CO)4(PNN) (2.7)), dependant on the combination of metal and ligand used. Conversion of monodentate Cr(CO)5(κ1-PNN) (2.4) to bidentate Cr(CO)4(κ2-PNN) (2.10) is achieved on reaction with trimethylamine N-oxide. The application of PNE ligands to ethylene oligomerisation systems has been carried out. All of the catalytic systems tested gave primarily polymer products, with no selective ethylene oligomerisation occurring. Chapter 3 describes the development of a modular synthetic route to novel iminophosphine compounds via reaction of imidoyl chlorides with trimethylsilyl phosphines. Using this synthetic process, a library of iminophosphines has been synthesised (3.1-3.26) with varying steric and electronic characteristics. The donor properties of the iminophosphines have been analysed by measurement of ǀ1JSe-Pǀ couplings of the derivative phosphine selenides, with all the compounds demonstrating good phosphine donor properties. Finally, the E/Z isomerisation behaviour of the PCN compounds has been studied, revealing that P-aryl substituted iminophosphines exist as a mixture of the E and Z isomers in equilibrium in solution. Chapter 4 details investigations into the coordination chemistry of iminophosphine ligands with chromium. A selection of ligands have been reacted with CrCl3(THF)3, forming a range of bidentate CrIII(κ2-PCN) complexes (e.g. CrCl3(THF)(Ph(PPh2)C=NPh), 4.1). The coordination of iminophosphine ligands with Cr(0) has shown that the ligands react with Cr(CO)6 to yield both mono- and bi-dentate products (e.g. Cr(CO)4(Ph(PiPr2)C=N(2,6-iPr2C6H3)) (4.7) and Cr(CO)5(Ph(PiPr2)C=N(2,6-iPr2C6H3)) (4.8), respectively). The denticity of these Cr(CO)(6-n)(κn-PCN) complexes can be controlled through the removal and addition of CO in the atmosphere. Chapter 5 recounts the use of the novel iminophosphines as ligands in selective ethylene oligomerisation systems. A wide range of catalytic conditions were tested, including varying the chromium source, solvent, reaction temperature and pressure, the use of polymer reducing additives, and the dosing of O2 into the reaction. It has been shown that a catalytic process using Cr(2-EH)3, 1 equivalent of iminophosphine 3.9, 49 bar C2H4, in methylcyclohexane at 60 °C, with 0.66 ppm O2 and 100 equivalents of ZnEt2 yields a highly active and selective ethylene tri-/tetramerisation process.
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Alzamly, Ahmed. "The Role of Aluminate in the Activation of Catalytic Systems for Ethylene Oligomerization". Thèse, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31024.
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The reaction mechanisms followed by ethylene polymerization and selective oligomerization (tri- and tetramerization) are conceptually very different, being a non-redox chain growth and a redox metallacycle ring expansion pathway respectively. With chromium being the metal of choice, metal oxidation states and the variation of ancillary ligand able to support specific metal oxidation states responsible for selective trimerization, tetramerization or nonselective oligomerization/polymerization were varied. In this research project we have explored a broad range of novel pyridine containing modified PN ligand scaffolds with the aim of probing the role of the pyridine donor substituent in stabilizing lower oxidation states and ultimately affecting the selectivity of the ethylene in the catalytic cycle. In this study, pyridine PNP pincer ligands in conjunction with chromium salts and alkylaluminium activators have been explored. Their catalytic activities toward ethylene oligomerization were rationalized through the isolation of different chromium-aluminate intermediates in different oxidation states during the catalytic reaction. Moreover, we explored other pyridine modification of NNP type ligand. Its anionic ligand shows a rare example of a Cr(II) hydride cluster which shows a high activity as a nonselective ethylene oligomerization catalyst. Finally, a cyclic PNPN type ligand was explored. The ligand enabled the isolation of a mix-valent Cr(I)/Cr(II) species which was found to be inactive toward ethylene oligomerization due to its geometric constraint.
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Hagan, Susan Anne. "Poly(lactic acid)-poly(ethylene glycol) copolymers for use as drug delivery systems". Thesis, University of Nottingham, 1998. http://eprints.nottingham.ac.uk/30646/.
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Block copolymers of polylactide and poly( ethylene glycol) (PLA-PEG) were investigated as biodegradable drug delivery systems. They are defined by the differing molecular weight ratios of polylactide to poly( ethylene glycol). Copolymers containing more hydrophilic PEG than hydrophobic PLA per molecule self-dispersed in water giving spherical nonionic micelles. Purification by gel permeation chromatography gave two peaks. The first peak only formed micelles (the second was PLA-depleted). Analysis by dynamic light scattering (DLS) and transmission electron microscopy (TEM) gave diameters of IS.6nm and 18.9nm for 1.5:2 and 2:5 PLA-PEG micelles respectively. PLA-PEG copolymers with more PLA than PEG per molecule (4:2 and 6:2 PLA-PEG) formed "solid particles" by the solvent-precipitation method. GPC purification again gave two peaks, but smaller second peaks. DLS analysis gave diameters of 15.1 nm and 20.8nm for 4:2 and 6:2 PLA-PEG particles respectively (confirmed by TEM and atomic force microscopy (AFM)). Static secondary ion mass spectrometry and X-ray photoelectron spectroscopy showed PEG at the surface of 4:2 and 6:2 PLA-PEG in water and acetone. Stability testing to salt suggested sterically stability. Rheological measurements determined PEG chain layer thicknesses, with the thickest chain for 2:5 PLA-PEG (where PEG chain length is 5000gmol-1 compared with 2000gmol-1). Testosterone and sudan black B (SBB), were used as "model" drugs with different hydrophobicities. Ultracentrifugation sedimentation velocity studies confirmed drug incorporation. Aromatic SBB loaded readily (≥59.0%w/w) compared with steroidal testosterone <2%w/w). Loading of testosterone esters of varying hydrophobicity into PLA-PEG particles showed little difference compared to between testosterone and SBB, suggesting that aromaticity is more significant. In vitro release studies (4:2 PLA-PEG particles/SBB) showed a small burst release, then linear release to twenty eight days. In vivo studies in the rat, using a radioactive marker, demonstrated extended blood circulation times for PLA-PEG micelles during the three-hour study, with increased blood levels and lower liver uptake for 1.5:2 over 2:5 PLA-PEG micelles. PLA-PEG particles were directed to the liver.
Książki na temat "Ethylene Systems"
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United States. National Aeronautics and Space Administration., red. Monitoring ethylene emissions from plants cultured for a controlled ecological life support system: Final technical report. [Washington, DC: National Aeronautics and Space Administration, 1995.
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United States. National Aeronautics and Space Administration., red. Monitoring ethylene emissions from plants cultured for a controlled ecological life support system: Final technical report. [Washington, DC: National Aeronautics and Space Administration, 1995.
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National Academies Press (U.S.), red. Review of the Environmental Protection Agency's draft IRIS assessment of tetrachloroethylene. Washington, D.C: National Academies Press, 2010.
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AAMI TIR56:2013/(R)2020; Guidance for the development, validation and routine control of an ethylene oxide sterilization process utilizing flexible bag systems for the sterilization of medical devices. AAMI, 2013. http://dx.doi.org/10.2345/9781570205194.
Pełny tekst źródłaCzęści książek na temat "Ethylene Systems"
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Johansson, Göte. "Affinity Partitioning in PEG-Containing Two-Phase Systems". W Poly(Ethylene Glycol) Chemistry, 73–84. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4899-0703-5_5.
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Apicella, A., B. Cappello, M. A. Del Nobile, M. I. La Rotonda, G. Mensitieri, L. Nicolais i S. Seccia. "Poly(ethylene oxide)-Based Delivery Systems". W ACS Symposium Series, 111–25. Washington, DC: American Chemical Society, 1994. http://dx.doi.org/10.1021/bk-1994-0545.ch009.
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Cristescu, S. M., i F. J. M. Harren. "Life science trace gas facility: a way towards top-research on biological systems". W Advances in Plant Ethylene Research, 441–42. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6014-4_93.
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Vidhyasekaran, P. "Ethylene Signaling System in Plant Innate Immunity". W Plant Hormone Signaling Systems in Plant Innate Immunity, 195–244. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-017-9285-1_4.
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Gamble, R. L., M. L. Coonfield, M. D. Randlett i G. E. Schaller. "The Role of Two-Component Systems in Ethylene Perception". W Biology and Biotechnology of the Plant Hormone Ethylene II, 59–64. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4453-7_12.
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Frauendorfer, Eric, Muhammad Babar, Timo Melchin i Wolf-Dieter Hergeth. "Monitoring of Vinyl Acetate–Ethylene Processes: An Industrial Perspective". W Polymer Reaction Engineering of Dispersed Systems, 183–214. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/12_2017_22.
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Dole, John M., i James E. Faust. "Postharvest management." W Cut flowers and foliages, 342–68. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247602.0008.
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Abstract This chapter focuses on the main issues that need to be considered at every step in the postharvest handling system of cut flowers, i.e. temperature, water, sanitation, carbohydrates, disease and ethylene. Their impacts on the vase life and quality of various species are discussed as well as the importance of optimizing the postharvest life of cut flowers and foliage by proper cultivar selection before planting and the use of appropriate production systems.
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Sri Nithya Mahottamananda, Jayapal, Dubey Vanchhit Kumar, Abdul Khaleel Afreen, S. Dinesh, Wahab Ashiq, P. N. Kadiresh i M. Thirumurugan. "Mechanical Characteristics of Ethylene Vinyl Acetate Mixed Beeswax Fuel for Hybrid Rockets". W Advances in Design and Thermal Systems, 389–400. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6428-8_31.
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Volodin, A. A., i B. P. Tarasov. "CVD-Synthesis Peculiarities of Carbon Nanomaterials from Ethylene with Gaseous Additions". W Carbon Nanomaterials in Clean Energy Hydrogen Systems - II, 177–81. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-0899-0_15.
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Nifant’ev, Ilya E., Leila Yu Ustynyuk i Dmitri N. Laikov. "A DFT Study of Ethylene Polymerization by Zirconocene-boron Catalytic Systems". W Organometallic Catalysts and Olefin Polymerization, 72–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-59465-6_7.
Pełny tekst źródłaStreszczenia konferencji na temat "Ethylene Systems"
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Graf, John C., Prashant S. Chintawar i J. R. Kittrell. "Photocatalytic Purification of Spacecraft Air: Ethylene Destruction". W International Conference On Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1998. http://dx.doi.org/10.4271/981803.
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Rujitanaroj, Pim-on, Nuttaporn Pimpha i Pitt Supaphol. "Preparation of Ultrafine Poly(ethylene oxide)/Poly(ethylene glycol) Fibers Containing Silver Nanoparticles as Antibacterial Coating". W 2007 2nd IEEE International Conference on Nano/Micro Engineered and Molecular Systems. IEEE, 2007. http://dx.doi.org/10.1109/nems.2007.352202.
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Deshmukh, Salim, Tore Larsen i Shanta Seereeram. "Digitalized Next Generation Mono Ethylene Glycol Regeneration Systems". W International Petroleum Technology Conference. International Petroleum Technology Conference, 2020. http://dx.doi.org/10.2523/19927-ms.
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Deshmukh, Salim, Tore Larsen i Shanta Seereeram. "Digitalized Next Generation Mono Ethylene Glycol Regeneration Systems". W Abu Dhabi International Petroleum Exhibition & Conference. Society of Petroleum Engineers, 2020. http://dx.doi.org/10.2118/202907-ms.
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Deshmukh, Salim, Tore Larsen i Shanta Seereeram. "Digitalized Next Generation Mono Ethylene Glycol Regeneration Systems". W International Petroleum Technology Conference. International Petroleum Technology Conference, 2020. http://dx.doi.org/10.2523/iptc-19927-ms.
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Lai, Antonella, Luigi De Dominicis, Roberta Fantoni, Gianfranco Giubileo, D. Piccinelli i Dan C. Dumitras. "Detection of ethylene traces by photoacoustic spectroscopy". W Medical Imaging 2003 Physiology and Function: Methods, Systems, and Applications, redaktorzy Alexis Carabelas, Giuseppe Baldacchini, Paolo Di Lazzaro i Dimitrios Zevgolis. SPIE, 2003. http://dx.doi.org/10.1117/12.513679.
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Seshimo, Y., Y. Ike, S. Kojima, Michio Tokuyama, Irwin Oppenheim i Hideya Nishiyama. "Brillouin and Raman Scattering Study of Ethylene Glycol Aqueous Solutions". W COMPLEX SYSTEMS: 5th International Workshop on Complex Systems. AIP, 2008. http://dx.doi.org/10.1063/1.2897819.
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Derelı, Ömer, Ebru Karakaş Sarikaya i Yusuf Erdoğdu. "Investigation of molecular and radical structures of ethylene glycol". W SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems. Author(s), 2018. http://dx.doi.org/10.1063/1.5078895.
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Tambwekar, Jyoti A., Robert M. Cowan, Jitendra A. Joshi, Peter F. Strom i Melvin S. Finstein. "Removal of Trace Concentrations of Ethylene from Air by Biofiltration: Preliminary Results". W International Conference On Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1998. http://dx.doi.org/10.4271/981614.
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Klassen, S. P., W. F. Campbell i B. G. Bugbee. "Effects of Low Ethylene Levels on USU-Apogee and Super-Dwarf Wheat". W International Conference On Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1999. http://dx.doi.org/10.4271/1999-01-2025.
Pełny tekst źródłaRaporty organizacyjne na temat "Ethylene Systems"
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Eshel, Amram, Jonathan P. Lynch i Kathleen M. Brown. Physiological Regulation of Root System Architecture: The Role of Ethylene and Phosphorus. United States Department of Agriculture, grudzień 2001. http://dx.doi.org/10.32747/2001.7585195.bard.
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Specific Objectives and Related Results: 1) Determine the effect of phosphorus availability on ethylene production by roots. Test the hypothesis that phosphorus availability regulates ethylene production Clear differences were found between the two plants that were studied. In beans ethylene production is affected by P nutrition, tissue type, and stage of development. There are genotypic differences in the rate of ethylene production by various root types and in the differential in ethylene production when P treatments are compared. The acceleration in ethylene production with P deficiency increases with time. These findings support the hypothesis that ethylene production may be enhanced by phosphorus deficiency, and that the degree of enhancement varies with genotype. In tomatoes the low-P level did not enhance significantly ethylene production by the roots. Wildtype cultivars and ethylene insensitive mutants behaved similarly in that respect. 2) Characterize the effects of phosphorus availability and ethylene on the architecture of whole root systems. Test the hypothesis that both ethylene and low phosphorus availability modify root architecture. In common bean, the basal roots give rise to a major fraction of the whole root system. Unlike other laterals these roots respond to gravitropic stimulation. Their growth angle determines the proportion of the root length in the shallow layers of the soil. A correlation between ethylene production and basal root angle was found in shallow rooted but not deep-rooted genotypes, indicating that acceleration of ethylene synthesis may account for the change in basal root angle in genotypes demonstrating a plastic response to P availability. Short-time gravitropic response of the tap roots of young bean seedlings was not affected by P level in the nutrient solution. Low phosphorus specifically increases root hair length and root hair density in Arabidopsis. We tested 7 different mutants in ethylene perception and response and in each case, the response to low P was lower than that of the wild-type. The extent of reduction in P response varied among the mutants, but every mutant retained some responsiveness to changes in P concentration. The increase in root hair density was due to the increase in the number of trichoblast cell files under low P and was not mediated by ethylene. Low P did not increase the number of root hairs forming from atrichoblasts. This is in contrast to ethylene treatment, which increased the number of root hairs partly by causing root hairs to form on atrichoblasts. 3) Assess the adaptive value of root architectural plasticity in response to phosphorus availability. A simulation study indicated that genetic variation for root architecture in common bean may be related to adaptation to diverse competitive environments. The fractal dimension of tomato root system was directly correlated with P level.
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Perl-Treves, Rafael, Rebecca Grumet, Nurit Katzir i Jack E. Staub. Ethylene Mediated Regulation of Sex Expression in Cucumis. United States Department of Agriculture, styczeń 2005. http://dx.doi.org/10.32747/2005.7586536.bard.
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Monoecious species such as melon and cucumber develop separate male and female (or bisexual) flowers on the same plant individual. They display complex genetic and hormonal regulation of sex patterns along the plant. Ethylene is known to play an important role in promoting femaleness and inhibiting male development, but many questions regarding critical sites of ethylene production versus perception, the relationship between ethylene and the sex determining loci, and the possible differences between melon and cucumber in this respect are still open. The general goal of the project was to elucidate the role of ethylene in determining flower sex in Cucumis species, melon and cucumber. The specific Objectives were: 1. Clone and characterize expression patterns of cucumber genes involved in ethylene biosynthesis and perception. 2. Genetic mapping of cloned genes and markers with respect to sex loci in melon and cucumber. 3. Produce and analyze transgenic melons altered in ethylene production or perception. In the course of the project, some modifications/adjustments were made: under Objective 2 (genetic mapping) a set of new mapping populations had to be developed, to allow better detection of polymorphism. Under Objective 3, cucumber transformation systems became available to us and we included this second model species in our plan. The main findings of our study support the pivotal role of ethylene in cucumber and melon sex determination and later stages of reproductive development. Modifying ethylene production resulted in profound alteration of sex patterns in melon: femaleness increased, and also flower maturation and fruit set were enhanced, resulting in earlier, more concentrated fruit yield in the field. Such effect was previously unknown and could have agronomic value. Our results also demonstrate the great importance of ethylene sensitivity in sex expression. Ethylene perception genes are expressed in sex-related patterns, e.g., gynoecious lines express higher levels of receptor-transcripts, and copper treatments that activate the receptor can increase femaleness. Transgenic cucumbers with increased expression of an ethylene receptor showed enhanced femaleness. Melons that expressed a defective receptor produced fewer hermaphrodite flowers and were insensitive to exogenous ethylene. When the expression of defective receptor was restricted to specific floral whorls, we saw that pistils were not inhibited by the blocked perception at the fourth whorl. Such unexpected findings suggest an indirect effect of ethylene on the affected whorl; it also points at interesting differences between melon and cucumber regarding the mode of action of ethylene. Such effects will require further study. Finally, our project also generated and tested a set of novel genetic tools for finer identification of sex determining genes in the two species and for efficient breeding for these characters. Populations that will allow easier linkage analysis of candidate genes with each sex locus were developed. Moreover, effects of modifier genes on the major femaleness trait were resolved. QTL analysis of femaleness and related developmental traits was conducted, and a comprehensive set of Near Isogenic Lines that differ in specific QTLs were prepared and made available for the private and public research. Marker assisted selection (MAS) of femaleness and fruit yield components was directly compared with phenotypic selection in field trials, and the relative efficiency of MAS was demonstrated. Such level of genetic resolution and such advanced tools were not used before to study these traits, that act as primary yield components to determine economic yields of cucurbits. In addition, this project resulted in the establishment of workable transformation procedures in our laboratories and these can be further utilized to study the function of sex-related genes in detail.
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Sisler, Edward C., Raphael Goren i Akiva Apelbaum. Controlling Ethylene Responses in Horticultural Crops at the Receptor Level. United States Department of Agriculture, październik 2001. http://dx.doi.org/10.32747/2001.7580668.bard.
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Ethylene is a plant hormone that controls many plant responses, such as growth, senescence, ripening, abscission and seed germination. Recently, 1-methy- cyclopropene (1-MCP), was shown to bind to ethylene receptor for a certain period of time and prevent ethylene action. The objectives of this research were to synthesize analogues of 1-MCP and test their potency to block the ethylene receptor and inhibit ethylene action. During the course of this project, procedures for synthesis and shipment of the cyclopropene compounds were developed as well assay procedures for each compound were worked out. Thirteen new compounds were synthesized. All of them are structural analogues of 1-MCP, with substitution in the 1-position and a side chain containing 2 to 10 carbons. After preliminary studies, nine promising compounds were selected for in-depth study. The potency of the compounds to inhibit ethylene action was tested on a wide scope of systems like: climacteric fruits (banana, avocado and tomato), the triple response (etiolated peas), and leaf abscission (citrus). As the putative inhibitors are suspected to compete for the site of binding and a competitive type of inhibition could be considered, a high concentration of ethylene (300 m1.L-1) was used to induce ripening and other physiological processes. The tests were conducted under extreme conditions which hasten ripening like treatment and storage at 22 to 25oC. There were fluctuations in the responses as related to the concentrations of the inhibitors. Some required much higher concentration to exert the same effect, while some, when applied at the same concentration, blocked the receptor for a longer period of time than the others. Some fruits and other plant organs responded differently to the same inhibitor, indicating differences in characteristics and availability of the ethylene receptors in the various tissues. The potency of the putative inhibitors was found to be greatly affected by their molecular structural and size. In addition, it was found that treatment with the inhibitor should be given before the onset of ethylene action In the case of fruit, treatment should be carried out before the pre-climacteric stage. Simultaneous treatment with ethylene and the inhibitors reduced the inhibitors' effect. The relationship between ethylene and the inhibitors is of a non-competitive nature. All the fruits treated with the putative inhibitors resumed normal ripening after recovery from the inhibition. This fact is of great importance when considering the inhibitors for practical use. The advantage of using inhibitors of ethylene action over inhibitors of ethylene production lies in the ability of the inhibitors of ethylene action to protect the tissue against both endogenous and exogenous ethylene, thus providing better overall protection. Our findings indicate that 1-MCP and its structural analogues are potent inhibitors of ethylene action capable of providing good protection against endogenous and exogenous ethylene. The fact that the compounds are in a gas phase and are non-phytotoxic, odorless and effective at minute concentrations, renders them promising candidates for commercial use. However, the development of water-soluble inhibitors will expand the potential use of the inhibitors in agriculture.
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Crisosto, Carlos, Susan Lurie, Haya Friedman, Ebenezer Ogundiwin, Cameron Peace i George Manganaris. Biological Systems Approach to Developing Mealiness-free Peach and Nectarine Fruit. United States Department of Agriculture, 2007. http://dx.doi.org/10.32747/2007.7592650.bard.
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Peach and nectarine production worldwide is increasing; however consumption is flat or declining because of the inconsistent eating quality experienced by consumers. The main factor for this inconsistent quality is mealiness or woolliness, a form of chilling injury that develops following shipping periods in the global fruit market today. Our research groups have devised various postharvest methods to prolong storage life, including controlled atmosphere and delayed storage; however, these treatments only delay mealiness. Mealiness texture results from disruption of the normal ripening process involving disassembly of cell wall material, and creates a soft fruit texture that is dry and grainy instead of juicy and smooth. Solving this problem is a prerequisite for increasing the demand for fresh peach and nectarine. Two approaches were used to reveal genes and their associated biochemical processes that can confer resistance to mealiness or wooliness. At the Volcani Center, Israel, a nectarine cultivar and the peach cultivar (isogenetic materials) from which the nectarine cultivar spontaneously arose, and at the Kearney Agricultural Center of UC Davis, USA, a peach population that segregates for quantitative resistance to mealiness was used for dissecting the genetic components of mealiness development. During our project we have conducted research integrating the information from phenotypic, biochemical and gene expression studies, proposed possible candidate genes and SNPs-QTLs mapping that are involved in reducing peach mealiness susceptibility. Numerous genes related to ethylene biosynthesis and its signal transduction, cell wall structure and metabolism, stress response, different transcription factor families were detected as being differentially accumulated in the cold-treated samples of these sensitive and less sensitive genotypes. The ability to produce ethylene and keep active genes involved in ethylene signaling, GTP-binding protein, EIN-3 binding protein and an ethylene receptor and activation of ethyleneresponsive fruit ripening genes during cold storage provided greater resistance to CI. Interestingly, in the functional category of genes differentially expressed at harvest, less chilling sensitive cultivar had more genes in categories related to antioxidant and heat sock proteins/chaperones that may help fruit to adapt to low temperature stress. The specific objectives of the proposed research were to: characterize the phenotypes and cell wall components of the two resistant systems in response to mealiness- inducing conditions; identify commonalities and specific differences in cell wall proteins and the transcriptome that are associated with low mealiness incidence; integrate the information from phenotypic, biochemical, and gene expression studies to identify candidate genes that are involved in reducing mealiness susceptibility; locate these genes in the Prunus genome; and associate the genes with genomic regions conferring quantitative genetic variation for mealiness resistance. By doing this we will locate genetic markers for mealiness development, essential tools for selection of mealiness resistant peach lines with improved fruit storability and quality. In our research, QTLs have been located in our peach SNPs map, and proposed candidate genes obtained from the integrated result of phenotypic, biochemical and gene expression analysis are being identified in our QTLs as an approach searching for consistent assistant markers for peach breeding programs.
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Avni, Adi, i Kirankumar S. Mysore. Functional Genomics Approach to Identify Signaling Components Involved in Defense Responses Induced by the Ethylene Inducing Xyalanase Elicitor. United States Department of Agriculture, grudzień 2009. http://dx.doi.org/10.32747/2009.7697100.bard.
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Plant-microbe interactions involve a large number of global regulatory systems, which are essential for plants to protect themselves against pathogen attack. An ethylene-inducing xylanase (EIX) of Trichoderma viride is a potent elicitor of plant defense responses, like hypersensitive response (HR), in specific cultivars of tobacco (Nicotiana tabacum) and tomato (Lycopersicon esculentum). The central goal of this proposal was to investigate the molecular mechanisms that allow plants to specifically activate defense responses after EIX treatment. We proposed to identify cellular signaling components involved in the induction of HR by the EIX elicitor. The molecular genetic analysis of the signal transduction pathway that modulates hypersensitive responses is an important step in understanding the induction of plant defense responses. The genes that mediate LeEIX2-EIX dependent activation of resistance mechanisms remain to be identified. We used two approaches to identify the cellular signaling components that induce HR mediated by the EIX elicitor. In the first approach, we performed a yeast two-hybrid screening using LeEix2 as bait to identify plant proteins that interact with it. In the second approach, we used virus-induced gene silencing (VIGS) for a high-throughput screen to identify genes that are required for the induction of LeEIX2-EIX mediated HR. VIGS will also be used for functional characterization of genes that will be identified during the yeast two-hybrid screen. This investigation will shed light on cellular processes and signaling components involved in induction of general plant defense against pathogens and will provide the basis for future biotechnological approaches to improve plant resistance to pathogens. Several genes were indentified by the two approaches. We used the VIGS and yeast two hybrid approaches to confirm that activity of the genes initially identified by different procedure. Two genes inhibit the induction of HR by the fungal elicitor in the different systems; Tobacco-Harpin binding protein 1 and cyclopropyl isomerase.
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Friedman, Haya, Julia Vrebalov, James Giovannoni i Edna Pesis. Unravelling the Mode of Action of Ripening-Specific MADS-box Genes for Development of Tools to Improve Banana Fruit Shelf-life and Quality. United States Department of Agriculture, styczeń 2010. http://dx.doi.org/10.32747/2010.7592116.bard.
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Fruit deterioration is a consequence of a genetically-determined fruit ripening and senescence programs, in which developmental factors lead to a climacteric rise of ethylene production in ethylene-sensitive fruits such as tomato and banana. Breeding of tomato with extended fruit shelf life involves the incorporation of a mutation in RIN, a MADS-box transcription factor participating in developmental control signalling of ripening. The RIN mode of action is not fully understood, and it may be predicted to interact with other MADS-box genes to execute its effects. The overall goal of this study was to demonstrate conservation of ripening control functions between banana and tomato and thus, the potential to genetically extend shelf-life in banana based on tools developed in tomato. The specific objectives were: 1. To increase the collection of potential RIN-like genes from banana; 2. To verify their action as developmental regulators; 3. To elucidate MADS-box gene mode of action in ripening control; 4. To create transgenic banana plants that express low levels of endogenous Le-RIN- like, MaMADS- gene(s). We have conducted experiments in banana as well as in tomato. In tomato we have carried out the transformation of the tomato rin mutant with the MaMADS1 and MaMADS2 banana genes. We have also developed a number of domain swap constructs to functionally examine the ripening-specific aspects of the RIN gene. Our results show the RIN-C terminal region is essential for the gene to function in the ripening signalling pathway. We have further explored the tomato genome databases and recovered an additional MADS-box gene necessary for fruit ripening. This gene has been previously termed TAGL1 but has not been functionally characterized in transgenic plants. TAGL1 is induced during ripening and we have shown via RNAi repression that it is necessary for both fleshy fruit expansion and subsequent ripening. In banana we have cloned the full length of six MaMADS box genes from banana and determined their spatial and temporal expression patterns. We have created antibodies to MaMADS2 and initiated ChI assay. We have created four types of transgenic banana plants designed to reduce the levels of two of the MaMADS box genes. Our results show that the MaMADS-box genes expression in banana is dynamically changing after harvest and most of them are induced at the onset of the climacteric peak. Most likely, different MaMADS box genes are active in the pulp and peel and they are differently affected by ethylene. Only the MaMADS2 box gene expression is not affected by ethylene indicating that this gene might act upstream to the ethylene response pathway. The complementation analysis in tomato revealed that neither MaMADS1 nor MaMADS2 complement the rin mutation suggesting that they have functionally diverged sufficiently to not be able to interact in the context of the tomato ripening regulatory machinery. The developmental signalling pathways controlling ripening in banana and tomato are not identical and/or have diverged through evolution. Nevertheless, at least the genes MaMADS1 and MaMADS2 constitute part of the developmental control of ripening in banana, since transgenic banana plants with reduced levels of these genes are delayed in ripening. The detailed effect on peel and pulp, of these transgenic plants is underway. So far, these transgenic bananas can respond to exogenous ethylene, and they seem to ripen normally. The response to ethylene suggest that in banana the developmental pathway of ripening is different than that in tomato, because rin tomatoes do not ripen in response to exogenous ethylene, although they harbor the ethylene response capability This study has a major contribution both in scientific and agricultural aspects. Scientifically, it establishes the role of MaMADS box genes in a different crop-the banana. The developmental ripening pathway in banana is similar, but yet different from that of the model plant tomato and one of the major differences is related to ethylene effect on this pathway in banana. In addition, we have shown that different components of the MaMADS-box genes are employed in peel and pulp. The transgenic banana plants created can help to further study the ripening control in banana. An important and practical outcome of this project is that we have created several banana transgenic plants with fruit of extended shelf life. These bananas clearly demonstrate the potential of MaMADS gene control for extending shelf-life, enhancing fruit quality, increasing yield in export systems and for improving food security in areas where Musaspecies are staple food crops.
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Friedman, Haya, Julia Vrebalov i James Giovannoni. Elucidating the ripening signaling pathway in banana for improved fruit quality, shelf-life and food security. United States Department of Agriculture, październik 2014. http://dx.doi.org/10.32747/2014.7594401.bard.
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Background : Banana being a monocot and having distinct peel and pulp tissues is unique among the fleshy fruits and hence can provide a more comprehensive understanding of fruit ripening. Our previous research which translated ripening discoveries from tomato, led to the identification of six banana fruit-associated MADS-box genes, and we confirmed the positive role of MaMADS1/2 in banana ripening. The overall goal was to further elucidate the banana ripening signaling pathway as mediated by MADS-boxtranscriptional regulators. Specific objectives were: 1) characterize transcriptional profiles and quality of MaMADS1/2 repressed fruit; 2) reveal the role of additional MaMADSgenes in ripening; 3) develop a model of fruit MaMADS-box mode of action; and 4) isolate new components of the banana ripening signaling pathway. Major conclusion: The functions of the banana MaMADS1-5 have been examined by complimenting the rinor the TAGL1-suppressed lines of tomato. Only MaMADS5 exhibited partial complementation of TAGL1-suppressed and rinlines, suggesting that while similar genes play corresponding roles in ripening, evolutionary divergence makes heterologous complementation studies challenging. Nevertheless, the partial complementation of tomato TAGL1-surpessed and rinlines with MaMADS5 suggests this gene is likely an important ripening regulator in banana, worthy of further study. RNA-seqtranscriptome analysis during ripening was performed on WT and MaMADS2-suppressed lines revealing additional candidate genes contributing to ripening control mechanisms. In summary, we discovered 39 MaMADS-box genes in addition to homologues of CNR, NOR and HB-1 expressed in banana fruits, and which were shown in tomato to play necessary roles in ripening. For most of these genes the expression in peel and pulp was similar. However, a number of key genes were differentially expressed between these tissues indicating that the regulatory components which are active in peel and pulp include both common and tissue-specific regulatory systems, a distinction as compared to the more uniform tomato fruit pericarp. Because plant hormones are well documented to affect fruit ripening, the expressions of genes within the auxin, gibberellin, abscisic acid, jasmonic acid, salicylic and ethylene signal transduction and synthesis pathways were targeted in our transcriptome analysis. Genes’ expression associated with these pathways generally declined during normal ripening in both peel and pulp, excluding cytokinin and ethylene, and this decline was delayed in MaMADS2-suppressed banana lines. Hence, we suggest that normal MaMADS2 activity promotes the observed downward expression within these non-ethylene pathways (especially in the pulp), thus enabling ripening progression. In contrast, the expressions of ACSand ACOof the ethylene biosynthesis pathway increase in peel and pulp during ripening and are delayed/inhibited in the transgenic bananas, explaining the reduced ethylene production of MaMADS2-suppressed lines. Inferred by the different genes’ expression in peel and pulp of the gibberellins, salicylic acid and cytokinins pathways, it is suggested that hormonal regulation in these tissues is diverse. These results provide important insights into possible avenues of ripening control in the diverse fruit tissues of banana which was not previously revealed in other ripening systems. As such, our transcriptome analysis of WT and ripening delayed banana mutants provides a starting point for further characterization of ripening. In this study we also developed novel evidence that the cytoskeleton may have a positive role in ripening as components of this pathway were down-regulated by MaMADS2 suppression. The mode of cytoskeleton involvement in fruit ripening remains unclear but presents a novel new frontier in ripening investigations. In summary, this project yielded functional understanding of the role and mode of action of MaMADS2 during ripening, pointing to both induction of ethylene and suppression of non-ethylene hormonal singling pathways. Furthermore, our data suggest important roles for cytoskeleton components and MaMADS5 in the overall banana ripening control network. Implications: The project revealed new molecular components/genes involved in banana ripening and refines our understanding of ripening responses in the peel and pulp tissues of this important species. This information is novel as compared to that derived from the more uniform carpel tissues of other highly studied ripening systems including tomato and grape. The work provides specific target genes for potential modification through genetic engineering or for exploration of useful genetic diversity in traditional breeding. The results from the project might point toward improved methods or new treatments to improve banana fruit storage and quality.
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O'Neill, Sharman, Abraham Halevy i Amihud Borochov. Molecular Genetic Analysis of Pollination-Induced Senescence in Phalaenopsis Orchids. United States Department of Agriculture, 1991. http://dx.doi.org/10.32747/1991.7612837.bard.
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The project investigated the molecular genetic and biochemical basis of pollination-induced senescence of Phalaenopsis flowers. This experimental system offered unique advantages in that senescence is strictly regulated by pollination, providing the basis to experimentally initiate and synchronize senescence in populations of flowers. The postpollination syndrome in the Phalaenopsis orchid system was dissected by investigating the temporal and spatial regulation of ACC synthase gene expression. In the stigma, pollen-borne auxin induces the expression of the auxin-regulated ACC synthase (PS-ACS2) gene, resulting in ACC synthesis within 1 h following pollination. Newly formed ACC is oxidized by basal constitutive ACC oxidase to ethylene, which then induces the expression of the ethylene-regulated ACC synthase(PS-ACS1) and oxidase (ACO1) genes for further autocatalytic production of ethylene. It is speculated that during the 6-h period following pollination, emasculation leads to the production or release of a sensitivity factor that sensitizes the cells of the stigma to ethylene. ACC and ethylene molecules are translocated from the stigma to the labellum and perianth where ethylene induces the expression of PS-ACS1 and ACO1 resulting in an increased production of ACC and ethylene. Organ-localized ethylene is responsible for inrolling and senescence of the labellum and perianth. The regulation of ethylene sensitivity and signal transduction events in pollinated flowers was also investigated. The increase in ethylene sensitivity appeared in both the flower column and the perianth, and was detected as early as 4 h after pollination. The increase in ethylene sensitivity following pollination was not dependent on endogenous ethylene production. Application of linoleic and linoleic acids to Phalaenopsis and Dendrobium flowers enhanced their senescence and promoted ethylene production. Several major lipoxygenase pathway products including JA-ME, traumatic acid, trans-2-hexenal and cis-3-hexenol, also enhanced flower senescence. However, lipoxygenase appears to not be directly involved in the endogenous regulation of pollination-induced Phalaenopsis and Dendrobium flower senescence. The data suggest that short-chain saturated fatty acids may be the ethylene "sensitivity factors" produced following pollination, and that their mode of action involves a decrease in the order of specific regions i the membrane lipid bilayer, consequently altering ethylene action. Examination of potential signal transduction intermediates indicate a direct involvement of GTP-binding proteins, calcium ions and protein phosphorylation in the cellular signal transduction response to ethylene following pollination. Modulations of cytosolic calcium levels allowed us to modify the flowers responsiveness to ethylene.
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Philosoph-Hadas, Sonia, Peter Kaufman, Shimon Meir i Abraham Halevy. Signal Transduction Pathway of Hormonal Action in Control and Regulation of the Gravitropic Response of Cut Flowering Stems during Storage and Transport. United States Department of Agriculture, październik 1999. http://dx.doi.org/10.32747/1999.7695838.bard.
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Original objectives: The basic goal of the present project was to increase our understanding of the cellular mechanisms operating during the gravitropic response of cut flowers, for solving their bending problem without affecting flower quality. Thus, several elements operating at the 3 levels o the gravity-induced signal transduction pathway, were proposed to be examined in snapdragon stems according to the following research goals: 1) Signaling: characterize the signal transduction pathway leading to the gravitropic response, regarding the involvement of [Ca2+]cyt as a mediator of IAA movement and sensitivity to auxin. 2) Transduction by plant hormones: a) Examine the involvement of auxin in the gravitropic response of flower stems with regard to: possible participation of auxin binding protein (ABP), auxin redistribution, auxin mechanism of action (activation of H+-ATPase) mediation by changes in [Ca2+]cyt and possible regulation of auxin-induced Ca2+ action b: calmodulin-activated or Ca2+-activated protein kinases (PK). b) Examine the involvement of ethylene in the gravitropic response of flower stems with regard to auxin-induced ethylene production and sensitivity of the tissue to ethylene. 3) Response: examine the effect of gravistimulation on invertase (associated with growth and elongation) activity and invertase gene expression. 4) Commercial practice: develop practical and simple treatments to prevent bending of cut flowers grown for export. Revisions: 1) Model systems: in addition to snapdragon (Antirrhinum majus L.), 3 other model shoe systems, consisting of oat (Avena sativa) pulvini, Ornithogalun 'Nova' cut flowers and Arabidopsis thaliana inflorescence, were targeted to confirm a more general mechanism for shoot gravitropism. 2 Research topics: the involvement of ABP, auxin action, PK and invertase in the gravitropic response of snapdragon stems could not be demonstrated. Alternatively, the involvement in the gravity signaling cascade of several other physiological mediators apart of [Ca2+]cyt such as: IP3, protein phosphorylation and actin cytoskeleton, was shown. Additional topics introduced: starch statolith reorientation, differential expression of early auxin responsive genes, and differential shoot growth. Background to the topic: The gravitropic bending response of flowering shoots occurring upon their horizontal placement during shipment exhibits a major horticultural problem. In spite of extensive studies in various aboveground organs, the gravitropic response was hardly investigated in flowering shoots. Being a complex multistep process that requires the participation of various cellular components acting in succession or in parallel, analysis of the negative gravitropic response of shoot includes investigation of signal transduction elements and various regulatory physiological mediators. Major achievements: 1) A correlative role for starch statoliths as gravireceptors in flowering shoot was initially established. 2) Differentially phosphorylated proteins and IP3 levels across the oat shoe pulvini, as well as a differential appearance of 2 early auxin-responsive genes in snapdragon stems were all detected within 5-30 minutes following gravistimulation. 3) Unlike in roots, involvement of actin cytoskeleton in early events of the gravitropic response of snapdragon shoots was established. 4) An asymmetric IAA distribution, followed by an asymmetric ethylene production across snapdragon stems was found following gravistimulation. 5) The gravity-induced differential growth in shoots of snapdragon was derived from initial shrinkage of the upper stem side and a subsequent elongation o the lower stem side. 6) Shoot bending could be successfully inhibited by Ca2+ antagonists (that serve as a basis for practical treatments), kinase and phosphatase inhibitors and actin-cytoskeleton modulators. All these agents did not affect vertical growth. The essential characterization of these key events and their sequence led us to the conclusion that blocking gravity perception may be the most powerful means to inhibit bending without hampering shoot and flower growth after harvest. Implications, scientific and agriculture: The innovative results of this project have provided some new insight in the basic understanding of gravitropism in flower stalks, that partially filled the gap in our knowledge, and established useful means for its control. Additionally, our analysis has advanced the understanding of important and fundamental physiological processes involved, thereby leading to new ideas for agriculture. Gravitropism has an important impact on agriculture, particularly for controlling the bending of various important agricultural products with economic value. So far, no safe control of the undesired bending problem of flower stalks has been established. Our results show for the first time that shoot bending of cut flowers can be inhibited without adverse effects by controlling the gravity perception step with Ca2+ antagonists and cytoskeleton modulators. Such a practical benefit resulting from this project is of great economic value for the floriculture industry.
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Lurie, Susan, John Labavitch, Ruth Ben-Arie i Ken Shackel. Woolliness in Peaches and Nectarines. United States Department of Agriculture, 1995. http://dx.doi.org/10.32747/1995.7570557.bard.
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The overall goal of the research was to understand the processes involved in the development of woolliness in peaches and nectarines. Four specific hypotheses were proposed and in the course of the research evidence was gathered t support two of them and to not support two others. The hypotheses and a summary of the evidence are outlined below. 1. That woolliness arises from an imbalance between the activities of the cell wall pectin degrading enzymes. Using 'Flavortop' nectarines and 'Hermoza' peaches as model systems, storage regimes were manipulated to induce or prevent woolliness. The expression (mRNA abundance), protein content (Western blotting), and activity of polygalacturonase (PG) and pectin esterase (PE) were followed. Expression of the enzymes was not different, but activity and the ratio between PG and PE activities were quite different in fruits developing woolliness or ripening normally. This was also examined by looking at the substrate, the pectin moiety of the cell wall, and i woolly fruit there were more high molecular weight pectins with regions of non-methylated galacturonic acid residues. Taking an in vitro approach it was found a) that PE activity was stable at 0oC while PG activity decreased; b) incubating the calcium pectate fraction of the cell wall with PE extracted from peaches caused the polymers to form a gel characteristic of the visual woolly symptoms in peaches. 2. That continued cell wall synthesis occurs during storage and contributes to structural changes i cell walls and improper dissolution and softening after storage. We tried to adapt our technique of adding 13C-glucose to fruit discs, which was used successfully to follow cell wall synthesis during tomato ripening. However, the difference in sugar content between the two fruits (4% in tomato and 12% in peach) meant that the 13C-glucose was much more diluted within the general metabolite pool. We were unable to see any cell wall synthesis which meant that either the dilution factor was too great, or that synthesis was not occurring. 3. That controlled atmosphere (CA) prevents woolliness by lowering all enzyme activities. CA was found to greatly reduce mRNA abundance of the cell wall enzymes compared to regular air storage. However, their synthesis and activity recovered during ripening after CA storage and did not after regular air storage. Therefore, CA prevented the inhibition of enzyme activation found in regular air storage. 4. That changes in cell wall turgor and membrane function are important events in the development of woolliness. Using a micro pressure probe, turgor was measured in cells of individual 'O'Henry' and 'CalRed' peaches which were woolly or healthy. The relationship between firmness and turgor was the same in both fruit conditions. These data indicate that the development and expression of woolliness are not associated with differences in membrane function, at least with regard to the factors that determine cell turgor pressure. In addition, during the period of the grant additional areas were explored. Encoglucanase, and enzyme metabolizing hemicellulose, was found to be highly expressed air stored, but not in unstored or CA stored fruit. Activity gels showed higher activity in air stored fruit as well. This is the first indication that other components of the cell wall may be involved in woolliness. The role of ethylene in woolliness development was also investigated at it was found a) that woolly fruits had decreased ability to produce ethylene, b) storing fruits in the presence of ethylene delayed the appearance of woolliness. This latter finding has implication for an inexpensive strategy for storing peaches and nectarines.