Academic literature on the topic 'Lipid order'
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Journal articles on the topic "Lipid order"
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Lafleur, Michel, Myer Bloom, and Pieter R. Cullis. "Lipid polymorphism and hydrocarbon order." Biochemistry and Cell Biology 68, no. 1 (January 1, 1990): 1–8. http://dx.doi.org/10.1139/o90-001.
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The use of 2H nuclear magnetic resonance for the characterization of the polymorphic behavior of lipids is illustrated. Different lipid phase preferences may be expected to influence the orientational order and its variation along the acyl chains. Several results are presented to support that view. An increase of motional freedom and a redistribution of the order along the acyl chains are observed during the lamellar-to-hexagonal phase transition, showing that the order profile is sensitive to the lipid phase symmetry. In addition, if the preferences for nonlamellar phases are not expressed explicitly, the presence of "nonbilayer" lipids constrained in bilayer environment induces increased hydrocarbon order. This suggests that order parameters of the acyl chains and lipid polymorphic tendencies are intimately related.Key words: lipid, polymorphism, 2H nuclear magnetic resonance, hydrocarbon order.
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Leonard, Catherine, Hélène Pollet, Christiane Vermylen, Nir Gov, Donatienne Tyteca, and Marie-Paule Mingeot-Leclercq. "Tuning of Differential Lipid Order Between Submicrometric Domains and Surrounding Membrane Upon Erythrocyte Reshaping." Cellular Physiology and Biochemistry 48, no. 6 (2018): 2563–82. http://dx.doi.org/10.1159/000492700.
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Background/Aims: Transient nanometric cholesterol- and sphingolipid-enriched domains, called rafts, are characterized by higher lipid order as compared to surrounding lipids. Here, we asked whether the seminal concept of highly ordered rafts could be refined with the presence of lipid domains exhibiting different enrichment in cholesterol and sphingomyelin and association with erythrocyte curvature areas. We also investigated how differences in lipid order between domains and surrounding membrane (bulk) are regulated and whether changes in order differences could participate to erythrocyte deformation and vesiculation. Methods: We used the fluorescent hydration- and membrane packing-sensitive probe Laurdan to determine by imaging mode the Generalized Polarization (GP) values of lipid domains vs the surrounding membrane. Results: Laurdan revealed the majority of sphingomyelin-enriched domains associated to low erythrocyte curvature areas and part of the cholesterol-enriched domains associated with high curvature. Both lipid domains were less ordered than the surrounding lipids in erythrocytes at resting state. Upon erythrocyte deformation (elliptocytes and stimulation of calcium exchanges) or membrane vesiculation (storage at 4°C), lipid domains became more ordered than the bulk. Upon aging and in membrane fragility diseases (spherocytosis), an increase in the difference of lipid order between domains and the surrounding lipids contributed to the initiation of domain vesiculation. Conclusion: The critical role of domain-bulk differential lipid order modulation for erythrocyte reshaping is discussed in relation with the pressure exerted by the cytoskeleton on the membrane.
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Lafleur, M., M. Bloom, E. F. Eikenberry, S. M. Gruner, Y. Han, and P. R. Cullis. "Correlation between lipid plane curvature and lipid chain order." Biophysical Journal 70, no. 6 (June 1996): 2747–57. http://dx.doi.org/10.1016/s0006-3495(96)79844-2.
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de Santis, Augusta, Ernesto Scoppola, Maria Francesca Ottaviani, Alexandros Koutsioubas, Lester C. Barnsley, Luigi Paduano, Gerardino D’Errico, and Irene Russo Krauss. "Order vs. Disorder: Cholesterol and Omega-3 Phospholipids Determine Biomembrane Organization." International Journal of Molecular Sciences 23, no. 10 (May 10, 2022): 5322. http://dx.doi.org/10.3390/ijms23105322.
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Lipid structural diversity strongly affects biomembrane chemico-physical and structural properties in addition to membrane-associated events. At high concentrations, cholesterol increases membrane order and rigidity, while polyunsaturated lipids are reported to increase disorder and flexibility. How these different tendencies balance in composite bilayers is still controversial. In this study, electron paramagnetic resonance spectroscopy, small angle neutron scattering, and neutron reflectivity were used to investigate the structural properties of cholesterol-containing lipid bilayers in the fluid state with increasing amounts of polyunsaturated omega-3 lipids. Either the hybrid 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine or the symmetric 1,2-docosahexaenoyl-sn-glycero-3-phosphocholine were added to the mixture of the naturally abundant 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine and cholesterol. Our results indicate that the hybrid and the symmetric omega-3 phospholipids affect the microscopic organization of lipid bilayers differently. Cholesterol does not segregate from polyunsaturated phospholipids and, through interactions with them, is able to suppress the formation of non-lamellar structures induced by the symmetric polyunsaturated lipid. However, this order/disorder balance leads to a bilayer whose structural organization cannot be ascribed to either a liquid ordered or to a canonical liquid disordered phase, in that it displays a very loose packing of the intermediate segments of lipid chains.
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Ho, Cojen, Simon J. Slater, and Christopher D. Stubbs. "Hydration and Order in Lipid Bilayers." Biochemistry 34, no. 18 (May 1995): 6188–95. http://dx.doi.org/10.1021/bi00018a023.
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Park, Soohyung, and Wonpil Im. "Analysis of Lipid Order States and Domains in Lipid Bilayer Simulations." Journal of Chemical Theory and Computation 15, no. 1 (November 23, 2018): 688–97. http://dx.doi.org/10.1021/acs.jctc.8b00828.
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Yordanova, Vesela, Rusina Hazarosova, Victoria Vitkova, Aneliya Kostadinova, Miglena Angelova, Albena Momchilova, Plamen Krastev, and Galya Staneva. "Oxidized Lipids Control Lipid Order and Phospholipase A2 Activity in Model Membranes." Proceedings of the Bulgarian Academy of Sciences 75, no. 4 (May 2, 2022): 581–89. http://dx.doi.org/10.7546/crabs.2022.04.13.
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Oxidative stress is an important etiologic factor in the pathogenesis of various diseases. The formation of oxidized phospholipid species in vivo induces membrane remodelling with direct pathological implications with a prominent inflammatory component. Secretory phospholipases A2 (sPLA2) are involved in the regulation of inflammation and immune response. Their activity is highly dependent on the lipid membrane composition, structure and organization. In this work, we studied the impact of oxidized phosphatidylcholines (OxPCs) on the membrane lipid order and the sPLA2 activity. The effects of two of the most physiologically active OxPCs, 1-palmitoyl-2-(5′-oxo-valeroyl)-sn-glycero- 3-phosphocholine (POVPC) and 1-palmitoyl-2-glutaroyl-sn-glycero-3- phosphocholine (PGPC) were compared using 1-palmitoyl-2-oleoyl-sn-glycero- 3-phosphocholine (POPC) vesicles. Both OxPCs reduce the membrane lipid order and sPLA2 activity at physiological temperature. Moreover, these changes depend on the chemical nature of the oxidized chains.
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Raggi, Carla, Marco Diociaiuti, Giulio Caracciolo, Federica Fratini, Luca Fantozzi, Giovanni Piccaro, Katia Fecchi, et al. "Caveolin-1 Endows Order in Cholesterol-Rich Detergent Resistant Membranes." Biomolecules 9, no. 7 (July 17, 2019): 287. http://dx.doi.org/10.3390/biom9070287.
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Cholesterol-enriched functional portions of plasma membranes, such as caveolae and rafts, were isolated from lungs of wild-type (WT) and caveolin-1 knockout (Cav-1 KO) mice within detergent resistant membranes (DRMs). To gain insight into their molecular composition we performed proteomic and lipid analysis on WT and Cav-1 KO-DRMs that showed predicted variations of proteomic profiles and negligible differences in lipid composition, while Langmuir monolayer technique and small and wide-angle X-ray scattering (SAXS-WAXS) were here originally introduced to study DRMs biophysical association state. Langmuir analysis of Cav-1 containing DRMs displayed an isotherm with a clear-cut feature, suggesting the coexistence of the liquid-ordered (Lo) phase typical of the raft structure, namely “cholesterol-rich Lo phase”, with a phase fully missing in Cav-1 KO that we named “caveolin-induced Lo phase”. Furthermore, while the sole lipid component of both WT and KO-DRMs showed qualitatively similar isotherm configuration, the reinsertion of recombinant Cav-1 into WT-DRMs lipids restored the WT-DRM pattern. X-ray diffraction results confirmed that Cav-1 causes the formation of a “caveolin-induced Lo phase”, as suggested by Langmuir experiments, allowing us to speculate about a possible structural model. These results show that the unique molecular link between Cav-1 and cholesterol can spur functional order in a lipid bilayer strictly derived from biological sources.
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Delamere, N. A., C. A. Paterson, D. Borchman, K. L. King, and S. A. Cawood. "Calcium transport, Ca2(+)-ATPase, and lipid order in rabbit ocular lens membranes." American Journal of Physiology-Cell Physiology 260, no. 4 (April 1, 1991): C731—C737. http://dx.doi.org/10.1152/ajpcell.1991.260.4.c731.
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Calcium transport was monitored by measuring ATP-dependent 45Ca uptake into membrane vesicles prepared from rabbit lens cortex. Calcium-stimulated adenosinetriphosphatase (Ca2(+)-ATPase) activity was also measured in the same membrane preparation. Both uptake and Ca2(+)-ATPase activity were inhibited by vanadate. Calcium activation of the uptake process was similar to that of the Ca2(+)-ATPase. Calcium uptake was prevented by calcium ionophore A23187, suggesting that the calcium transported into the vesicles remains diffusible. The ATP-dependent calcium uptake probably represents the transport of calcium into “inside-out” membrane vesicles by the Ca2(+)-ATPase mechanism that normally shifts calcium outward from the lens cytoplasm. The temperature dependence of the Ca2(+)-ATPase and the calcium uptake process was determined. Because lipid order can influence Ca2(+)-ATPase function, we attempted to correlate calcium transport with the physical state of the membrane lipids. Infrared spectroscopy was used to determine the temperature dependence of the CH2 symmetric stretching frequency (an order parameter) in the lipids. A similarity was noted between the temperature-dependence curves for lipid order, Ca2(+)-ATPase, and calcium uptake rate. Entropy, enthalpy, and transition temperature calculated for the Ca2(+)-ATPase and calcium uptake process were in the same range as those parameters calculated for the lipid-phase transition.
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Becker, Kevin W., Felix J. Elling, Marcos Y. Yoshinaga, Andrea Söllinger, Tim Urich, and Kai-Uwe Hinrichs. "Unusual Butane- and Pentanetriol-Based Tetraether Lipids in Methanomassiliicoccus luminyensis, a Representative of the Seventh Order of Methanogens." Applied and Environmental Microbiology 82, no. 15 (May 13, 2016): 4505–16. http://dx.doi.org/10.1128/aem.00772-16.
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ABSTRACTA new clade of archaea has recently been proposed to constitute the seventh methanogenic order, theMethanomassiliicoccales, which is related to theThermoplasmatalesand the uncultivated archaeal clades deep-sea hydrothermal ventEuryarchaeotagroup 2 and marine group IIEuryarchaeotabut only distantly related to other methanogens. In this study, we investigated the membrane lipid composition ofMethanomassiliicoccus luminyensis, the sole cultured representative of this seventh order. The lipid inventory ofM. luminyensiscomprises a unique assemblage of novel lipids as well as lipids otherwise typical for thermophilic, methanogenic, or halophilic archaea. For instance, glycerol sesterpanyl-phytanyl diether core lipids found mainly in halophilic archaea were detected, and so were compounds bearing either heptose or methoxylated glycosidic head groups, neither of which have been reported so far for other archaea. The absence of quinones or methanophenazines is consistent with a biochemistry of methanogenesis different from that of the methanophenazine-containing methylotrophic methanogens. The most distinctive characteristic of the membrane lipid composition ofM. luminyensis, however, is the presence of tetraether lipids in which one glycerol backbone is replaced by either butane- or pentanetriol, i.e., lipids recently discovered in marine sediments. Butanetriol dibiphytanyl glycerol tetraether (BDGT) constitutes the most abundant core lipid type (>50% relative abundance) inM. luminyensis. We have thus identified a source for these unusual orphan lipids. The complementary analysis of diverse marine sediment samples showed that BDGTs are widespread in anoxic layers, suggesting an environmental significance ofMethanomassiliicoccalesand/or related BDGT producers beyond gastrointestinal tracts.IMPORTANCECellular membranes of members of all three domains of life,Archaea,Bacteria, andEukarya, are largely formed by lipids in which glycerol serves as backbone for the hydrophobic alkyl chains. Recently, however, archaeal tetraether lipids with either butanetriol or pentanetriol as a backbone were identified in marine sediments and attributed to uncultured sediment-dwelling archaea. Here we show that the butanetriol-based dibiphytanyl tetraethers constitute the major lipids inMethanomassiliicoccus luminyensis, currently the only isolate of the novel seventh order of methanogens. Given the absence of these lipids in a large set of archaeal isolates, these compounds may be diagnostic for theMethanomassiliicoccalesand/or closely related archaea.
Dissertations / Theses on the topic "Lipid order"
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Gonzalez, Laurie J. "The influence of membrane lipid order on cell shape and microvesiculation in human erythrocytes /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1615.pdf.
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Gonzalez, Laurie Jackson. "The Influence of Membrane Lipid Order on Cell Shape and Microvesiculation in Human Erythrocytes." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1058.
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Exposure of human erythrocytes to elevated intracellular calcium causes alterations in cell shape and stimulates shedding of the cell membrane in the form of microvesicles. We hypothesized that both the shape transition and microvesiculation are influenced by microscopic membrane physical properties such as lipid order. To test this hypothesis, membrane properties were manipulated by varying the experimental temperature, membrane cholesterol content, and the internal ionic environment. Changes in membrane order were assessed using steady-state fluorescence spectroscopy with an environment-sensitive probe, laurdan. Our observations led us to the following conclusions: 1) the modest temperature dependence of membrane structure observed with laurdan is shifted to lower temperatures and becomes more cooperative upon removal of membrane cholesterol, 2) the calcium-induced shape change observed in erythrocytes requires a decrease in membrane order, 3) the influence of membrane order is not limited to shape transitions induced only by calcium, and 4) decreased order is also a permissive factor for microvesicle shedding. Our data suggest that while the mechansims that regulate the shape transition and the release of microvesicles are different, they both require a state of membrane disorder.
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Dinic, Jelena. "Plasma membrane order; the role of cholesterol and links to actin filaments." Doctoral thesis, Stockholms universitet, Wenner-Grens institut, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-62279.
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The connection between T cell activation, plasma membrane order and actin filament dynamics was the main focus of this study. Laurdan and di-4-ANEPPDHQ, membrane order sensing probes, were shown to report only on lipid packing rather than being influenced by the presence of membrane-inserted peptides justifying their use in membrane order studies. These dyes were used to follow plasma membrane order in live cells at 37°C. Disrupting actin filaments had a disordering effect while stabilizing actin filaments had an ordering effect on the plasma membrane, indicating there is a basal level of ordered domains in resting cells. Lowering PI(4,5)P2 levels decreased the proportion of ordered domains strongly suggesting that the connection of actin filaments to the plasma membrane is responsible for the maintaining the level of ordered membrane domains. Membrane blebs, which are detached from the underlying actin filaments, contained a low fraction of ordered domains. Aggregation of membrane components resulted in a higher proportion of ordered plasma membrane domains and an increase in cell peripheral actin polymerization. This strongly suggests that the attachment of actin filaments to the plasma membrane induces the formation of ordered domains. Limited cholesterol depletion with methyl-beta-cyclodextrin triggered peripheral actin polymerization. Cholesterol depleted cells showed an increase in plasma membrane order as a result of actin filament accumulation underneath the membrane. Moderate cholesterol depletion also induced membrane domain aggregation and activation of T cell signaling events. The T cell receptor (TCR) aggregation caused redistribution of domains resulting in TCR patches of higher order and the bulk membrane correspondingly depleted of ordered domains. This suggests the preexistence of small ordered membrane domains in resting T cells that aggregate upon cell activation. Increased actin polymerization at the TCR aggregation sites showed that actin polymerization is strongly correlated with the changes in the distribution of ordered domains. The distribution of the TCR in resting cells and its colocalization with actin filaments is cell cycle dependent. We conclude that actin filament attachment to the plasma membrane, which is regulated via PI(4,5)P2, plays a crucial role in the formation of ordered domains.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 4: Manuscript.
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Kress, Alla. "Probing molecular orientational order of lipid reporters and MHC Class I protein in cell membranes using polarization-resolved fluorescence imaging." Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX30046.
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L'organisation orientationnelle bio-moléculaire des lipides et des protéines dans la membrane plasmique constitue un facteur important dans les processus biologiques au cours desquelles les fonctions peuvent être reliées aux mécanismes d'orientation et d'organisation. Le concept de séparation transitoire des phases à l'échelle nanométrique dans les domaines ordonnés et désordonnés, aussi appelé « radeau lipidique », est maintenant largement accepté. De plus, les domaines ordonnés contiennent des protéines de signalisation, ce qui souligne l'importance des séparations de phase au cours des processus de signalisation. Dans cette thèse de doctorat, nous avons étudié l'ordre orientationnel moléculaire de la protéine de signalisation MHC Class I et de reporters lipidiques tels que di-8-ANEPPQ et DiI(C18). Nous avons étudié l'ordre orientationnel moléculaire de la protéine de signalisation MHC Class I et des reporters lipidiques par imagerie d'anisotropie de fluorescence résolue en polarisation. Nous avons observé l'influence du cytosquelette d'actine sur l'ordre orientationnel moléculaire de la protéine MHC et des reporters lipidiques dans la membrane plasmique. De plus, nous avons trouvé que l'ordre orientationnel moléculaire des reporters dépend de la morphologie cellulaire. Nous avons examiné les plis membranaires en modifiant la forme des cellules de façon mécanique ou pharmacologiqueBiomolecular orientational organization of lipids and proteins in the plasma membrane is a crucial factor in biological processes where functions can be closely related to orientation and ordering mechanisms. The concept of transient nanosized phase separations in ordered and disordered domains, called "lipid rafts" is now widely accepted. Furthermore, the ordered domains are enriched in signaling proteins, which highlights the crucial impact of phase separation during the signaling processes. While this field has been so far largely addressed by studying the translational diffusion behavior of membrane proteins and lipid reporters by Single Molecule Tracking (SMT) or Fluorescence Correlation Spectroscopy (FCS), only little is known about the orientational behavior of signaling proteins and lipid reporters in the plasma membrane. In this PhD thesis we investigated the molecular orientational order of the signaling molecule MHC Class I protein using fluorescence anisotropy imaging as well as of lipid reporter di-8-ANEPPQ using polarization-resolved fluorescence imaging. Fluorescence anisotropy imaging requires a fluorescent label rigidly attached to the system under study, able to report its orientational order behavior. Thus, MHC Class I protein has been successfully labeled in a rigid way. We analyzed the orientational order of MHC Class I protein quantitatively in the endomembrane and plasma membrane and we found that the orientational order of MHC Class I protein in both membranes depends primarily on the maturation state of the protein and its interaction with the cytoskeleton
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Guidi, Henrique Santos. "Modelos estatísticos para a transição ordem - desordem de camadas lipídicas." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-27032013-130925/.
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Lipídios em solução aquosa formam uma variedade de estruturas diferentes que incluem monocamadas de surfactantes na interface água-ar, conhecidas como monocamadas de Langmuir, como também vesículas unilamelares ou plurilamelares no interior da solução. Sob variação de temperatura, estas estruturas apresentam diferentes fases, observadas através de calorimetria ou variação isotérmica de pressão lateral. Entre as fases apresentadas por estas estruturas, as duas mais importantes se diferenciam pela ordem das cadeias lipídicas. Entendemos que do ponto de vista das fases termodinâmicas, simplificado e qualitativo, monocamadas de Langmuir e bicamadas lipídicas constituem o mesmo sistema físico sob vínculos diferentes. Neste trabalho, desenvolvemos um modelo estatístico para o estudo da transição ordem-desordem destes sistemas, que inclui flutuações de densidade, estas ausentes no modelo de Doniach, de 1980, a base para muitos estudos teóricos para transições de fase de sistemas lipídicos. Flutuações de densidade são fundamentais na descrição de vesículas lipídicas carregadas, compostas de surfactante cuja cabeça polar se dissocia em água. O estudo em laboratório das propriedades térmicas e estruturais de membranas artificiais de lipídios carregados _e relativamente recente, e foi desenvolvido em grande parte no Laboratório de Biofísica do IFUSP. Tais membranas apresentam comportamento distinto das membranas neutras, notoriamente influenciado pela concentração de sal na solução. Isto motivou o desenvolvimento de uma segunda versão do modelo, na qual passamos a descrever a cabeça polar do lipídio em termos de um par de cargas opostas, sendo que a camada lipídica foi acoplada ao modelo primitivo restrito na rede, que desempenha o papel da solução salina. O primeiro modelo foi estudado por aproximação de campo médio e por simulações de Monte Carlo, e o segundo modelo foi investigado apenas através de simulações numéricas. O estudo do modelo carregado foi precedido por uma investigação criteriosa das técnicas de simulação de sistemas com interação Coulombiana, resultando no desenvolvimento de uma metodologia adequada a condições de contorno não isotrópicas e com custo computacional reduzido. Os modelos estatísticos propostos por nós levaram a dois resultados importantes. O modelo para camadas lipídicas neutras é, até hoje, o único modelo estatístico que descreve tanto a transição gel-fluido de bicamadas lipídicas, como a transição líquido condensado - líquido expandido\" de monocamadas de Langmuir, além de descrever também a transição líquido expandido gás na interface água-ar. O modelo para camadas lipídicas que se dissociam em água reproduz a variação abrupta na dissociação, concomitante com a transição ordem-desordem, propriedade que permite interpretar estudos experimentais relativos à condutividade das soluções lipídicas correspondentes.Lipids in aqueous solution form a variety of different structures which include monolayers of surfactants at the water-air interface, known as Langmuir monolayers, as well as unilamellar or plurilamellar vesicles within the solution. Under temperature variation, these structures display different phases, observed through calorimetry or isothermal variation of lateral pressure. Among the phases presented by these structures, the two most important differ in the order of the lipid chains. From the point of view of the thermodynamic phases, our understanding is that Langmuir monolayers and lipid bilayers constitute the same physical system under different constraints. In this work, we develop a statistical model for the order - disorder transition of lipid bilayers which adds density fluctuations to Doniach\'s 1980 model, which has been considered the basis for many theoretical studies for lipid systems phase transitions. Density fluctuations are essential in the description of the properties of charged vesicles in solution, which consist of surfactants whose polar head dissociates in water. The study in the laboratory of thermal and structural properties of artificial charged lipid membranes is relatively new, and was developed largely in the IFUSP Laboratory of Biophysics. Such membranes exhibit distinct behavior if compared to neutral membranes, notoriously influenced by the solution salt concentration. The experimental investigations motivated us to develop a second model, in which we describe the polar headgroups through a pair of opposite charges. The lipid layer is attached to the lattice restricted primitive model, which plays the role of the saline solution. The first model was studied both through a mean-field approximation as well as through Monte Carlo simulations, whereas the second model was investigated only through numerical simulations. The study of the charged model was preceded by a thorough investigation of the simulation techniques for Coulomb interaction systems, leading to the development of a methodology suitable for non isotropic boundary conditions and with reduced computational cost. The statistical models proposed by us led to two important results. To our knowledge, our model for neutral lipid layers is the only statistical model which, aside from describing simultaneously both the gel-fluid transition of lipid bilayers and the condensed liquid - expanded liquid transition of Langmuir monolayers, also describes the gas- expanded liquid transition at the air-water interface. The model for lipid layers that dissociate in water reproduces the abrupt change in dissociation, concomitant with the order-disorder transition, a property that allows us to interpret experimental studies related to conductivity of the corresponding lipid solutions.
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Vogel, Alexander, Jörg Nikolaus, Katrin Weise, Gemma Triola, Herbert Waldmann, Roland Winter, Andreas Herrmann, and Daniel Huster. "Interaction of the human N-Ras protein with lipid raft model membranes of varying degrees of complexity." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191006.
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Ternary lipid mixtures composed of cholesterol, saturated (frequently with sphingosine backbone), and unsaturated phospholipids show stable phase separation and are often used as model systems of lipid rafts.
Yet, their ability to reproduce raft properties and function is still debated. We investigated the properties and functional aspects of three lipid raft model systems of varying degrees of biological relevance – PSM/POPC/Chol, DPPC/POPC/Chol, and DPPC/DOPC/Chol – using 2H solidstate
nuclear magnetic resonance (NMR) spectroscopy, fluorescence microscopy, and atomic force microscopy. While some minor differences were observed, the general behavior and properties of all three model mixtures were similar to previously investigated influenza envelope
lipid membranes, which closely mimic the lipid composition of biological membranes. For the investigation of the functional aspects, we employed the human N-Ras protein, which is posttranslationally modified by two lipid
modifications that anchor the protein to the membrane. It was previously shown that N-Ras preferentially resides in liquid-disordered domains and exhibits a time-dependent accumulation in the domain boundaries of influenza envelope lipid membranes. For all three model mixtures,
we observed the same membrane partitioning behavior for N-Ras. Therefore, we conclude that even relatively simple models of raft membranes are able to reproduce many of their specific properties and functions.
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Meyer, Thomas, Dong Jae Baek, Robert Bittman, Ivan Haralampiev, Peter Müller, Andreas Herrmann, Daniel Huster, and Holger A. Scheidt. "Membrane properties of cholesterol analogs with an unbranched aliphatic side chain." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-190979.
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The interactions between cholesterol and other membrane molecules determine important membrane properties. It was shown that even small changes in the molecular structure of cholesterol have a crucial influence on these interactions. We recently reported that in addition to alterations in the tetracyclic ring structure, the iso-branched side chain of cholesterol also has a significant impact on membrane properties (Scheidt H. et al. 2013 Angew. Chem. Int. Ed. Engl. 52, 12848-12851). Here we used synthetic cholesterol analogs to investigate the influence of an unbranched aliphatic side chain of different length. The 2H NMR order parameter of the phospholipid chains and therefore the molecular packing of the phospholipid molecules shows a significant dependence on the sterol’s alkyl side chain length, while , membrane permeation studied by a dithionite ion permeation assay and lateral diffusion measured by 1H MAS pulsed field gradient NMR are less influenced. To achieve the same molecular packing effect similar to that of an iso-branched aliphatic side chain, a longer unbranched side chain (n-dodecyl instead of n-octyl) at C17 of cholesterol is required. Obviously, sterols having a branched iso- alkyl chain with two terminal methyl groups exhibit altered cholesterol-phospholipid-interactions compared to analogous molecules with a straight unbranched chain.
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Vogel, Alexander, Jörg Nikolaus, Katrin Weise, Gemma Triola, Herbert Waldmann, Roland Winter, Andreas Herrmann, and Daniel Huster. "Interaction of the human N-Ras protein with lipid raft model membranes of varying degrees of complexity." de Gruyter, 2014. https://ul.qucosa.de/id/qucosa%3A14050.
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Ternary lipid mixtures composed of cholesterol, saturated (frequently with sphingosine backbone), and unsaturated phospholipids show stable phase separation and are often used as model systems of lipid rafts.
Yet, their ability to reproduce raft properties and function is still debated. We investigated the properties and functional aspects of three lipid raft model systems of varying degrees of biological relevance – PSM/POPC/Chol, DPPC/POPC/Chol, and DPPC/DOPC/Chol – using 2H solidstate
nuclear magnetic resonance (NMR) spectroscopy, fluorescence microscopy, and atomic force microscopy. While some minor differences were observed, the general behavior and properties of all three model mixtures were similar to previously investigated influenza envelope
lipid membranes, which closely mimic the lipid composition of biological membranes. For the investigation of the functional aspects, we employed the human N-Ras protein, which is posttranslationally modified by two lipid
modifications that anchor the protein to the membrane. It was previously shown that N-Ras preferentially resides in liquid-disordered domains and exhibits a time-dependent accumulation in the domain boundaries of influenza envelope lipid membranes. For all three model mixtures,
we observed the same membrane partitioning behavior for N-Ras. Therefore, we conclude that even relatively simple models of raft membranes are able to reproduce many of their specific properties and functions.
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Meyer, Thomas, Dong Jae Baek, Robert Bittman, Ivan Haralampiev, Peter Müller, Andreas Herrmann, Daniel Huster, and Holger A. Scheidt. "Membrane properties of cholesterol analogs with an unbranched aliphatic side chain: Membrane properties of cholesterol analogs with an unbranchedaliphatic side chain." Universität Leipzig, 2014. https://ul.qucosa.de/id/qucosa%3A14046.
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The interactions between cholesterol and other membrane molecules determine important membrane properties. It was shown that even small changes in the molecular structure of cholesterol have a crucial influence on these interactions. We recently reported that in addition to alterations in the tetracyclic ring structure, the iso-branched side chain of cholesterol also has a significant impact on membrane properties (Scheidt H. et al. 2013 Angew. Chem. Int. Ed. Engl. 52, 12848-12851). Here we used synthetic cholesterol analogs to investigate the influence of an unbranched aliphatic side chain of different length. The 2H NMR order parameter of the phospholipid chains and therefore the molecular packing of the phospholipid molecules shows a significant dependence on the sterol’s alkyl side chain length, while , membrane permeation studied by a dithionite ion permeation assay and lateral diffusion measured by 1H MAS pulsed field gradient NMR are less influenced. To achieve the same molecular packing effect similar to that of an iso-branched aliphatic side chain, a longer unbranched side chain (n-dodecyl instead of n-octyl) at C17 of cholesterol is required. Obviously, sterols having a branched iso- alkyl chain with two terminal methyl groups exhibit altered cholesterol-phospholipid-interactions compared to analogous molecules with a straight unbranched chain.
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Danylchuk, Dmytro. "Environment-sensitive targeted fluorescent probes for live-cell imaging." Thesis, Strasbourg, 2021. http://www.theses.fr/2021STRAF012.
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Le ciblage, l'imagerie et le sondage spécifiques des membranes plasmiques et des organites intracellulaires peuvent être faits par des sondes fluorescentes à façon sensibles à la polarité. Ici, un nouveau fragment ciblant la membrane plasmique à été développé et testé dans cinq colorants cyanines, montrant d'excellentes performances en microscopie cellulaire et in vivo. Le fragment à été greffé à un fluorophore solvatochrome Prodan, donnant une sonde de membrane plasmique avec une sensibilité élevée à l'ordre lipidique. Le rouge de Nil, greffé aux fragments avec les chaînes alkyles C12 et C4, à donné deux sondes solvatochromes à membrane plasmique : NR12A pour la microscopie conventionnelle, et NR4A pour la microscopie à super-résolution PAINT. Le rouge de Nil avec des groupes ciblant les organites à donné un éventail de sondes sensibles à la polarité et à l'ordre lipidique dans les membranes des organites. Les sondes synthétisées trouveront des applications en bioimagerie, biologie cellulaire, biophysique ou mécanobiologieSpecific targeting, imaging and probing of cell plasma membranes and intracellular organelles can be addressed by rationally designed polarity-sensitive fluorescent probes. Here, a new efficient plasma membrane-targeting moiety was developed and tested in five cyanine dyes, showing excellent performance in cellular and in vivo microscopy. Next, the targeting moiety was grafted to a solvatochromic dye Prodan, yielding a plasma membrane probe with high lipid order sensitivity. Modifying a Nile Red using the moieties with varied alkyl chain lengths resulted in two solvatochromic plasma membrane probes: NR12A with high affinity to membranes for conventional microscopy, and NR4A, a low-affinity probe for PAINT super-resolution microscopy. Tethering Nile Red with organelle-targeted groups yielded an array of probes, able to sense polarity and lipid order in organelle membranes. The synthesized probes will find applications in bioimaging, cell biology, biophysics or mechanobiology
Books on the topic "Lipid order"
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Sadeghi, Sara. Order and membrane organization in chlorhexidine-lipid mixtures. St. Catharines, Ont: Brock University, Dept. of Physics, 2007.
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Kanduč, M., A. Schlaich, E. Schneck, and R. R. Netz. Interactions between biological membranes: theoretical concepts. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198789352.003.0012.
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In this chapter we review the various types of generic (non-specific) forces acting between lipid membranes in an aqueous environment and discuss the underlying mechanisms, with particular focus on the competing roles of enthalpic and entropic contributions. The interaction free energy (or interaction potential) is typically the result of a subtle interplay of several, often antagonistic contributions with comparable magnitude. First, we will briefly introduce the underlying physics of various kinds of surface–surface interactions, starting with theories of van der Waals and undulation interactions, covering electrostatics, depletion, and order–parameter fluctuation effects as well. We then turn our attention to a strong and universal repulsive force at small membrane–membrane separations, namely the hydration interaction. It has been under debate and investigation for decades and is not well captured by continuum approximations, thus here we will mainly rely on atomistic simulation techniques.
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Ducruix, Arnaud, and Richard Giegé, eds. Crystallization of Nucleic Acids and Proteins. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780199636792.001.0001.
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Crystallography is the major method of determining structures of biological macromolecules yet crystallization techniques are still regarded as difficult to perform. This new edition of Crystallization of Nucleic Acids and Proteins: A Practical Approach continues in the vein of the first edition by providing a detailed and rational guide to producing crystals of proteins and nucleic acids of sufficient quantity and quality for diffraction studies. It has been thoroughly updated to include all the major new techniques such as the uses of molecular biology in structural biology (maximizing expression systems, sequence modifications to enable crystallization, and the introduction of anomalous scatterers); diagnostic analysis of prenucleation and nucleation by spectroscopic methods; and the two- dimensional electron crystallography of soluble proteins on planar lipid films. As well as an introduction to crystallogenesis, the other topics covered are: Handling macromolecular solutions, experimental design, seeding, proceeding from solutions to crystals Crystallization in gels Crystallization of nucleic acid complexes and membrane proteins Soaking techniques Preliminary characterization of crystals in order to tell whether they are suitable for diffraction studies. As with all Practical Approach books the protocols have been written by experienced researchers and are tried an tested methods. The underlying theory is brought together with the laboratory protocols to provide researchers with the conceptual and methodological tools necessary to exploit these powerful techniques. Crystallization of Nucleic Acids and Proteins: A Practical Approach 2e will be an invaluable manual of practical crystallization methods to researchers in molecular biology, crystallography, protein engineering, and biological chemistry.
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Roe, Simon, ed. Protein Purification Techniques. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780199636747.001.0001.
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Proteins are an integral part of molecular and cellular structure and function and are probably the most purified type of biological molecule. In order to elucidate the structure and function of any protein it is first necessary to purify it. Protein purification techniques have evolved over the past ten years with improvements in equipment control, automation, and separation materials, and the introduction of new techniques such as affinity membranes and expanded beds. These developments have reduced the workload involved in protein purification, but there is still a need to consider how unit operations linked together to form a purification strategy, which can be scaled up if necessary. The two Practical Approach books on protein purification have therefore been thoroughly updated and rewritten where necessary. The core of both books is the provision of detailed practical guidelines aimed particularly at laboratory scale purification. Information on scale-up considerations is given where appropriate. The books are not comprehensive but do cover the major laboratory techniques and common sources of protein. Protein Purification Techniques focuses on unit operations and analytical techniques. It starts with an overview of purification strategy and then covers initial extraction and clarification techniques. The rest of the book concentrates on different purification methods with the emphasis being on chromatography. The final chapter considers general scale-up considerations. Protein Purification Applications describes purification strategies from common sources: mammalian cell culture, microbial cell culture, milk, animal tissue, and plant tissue. It also includes chapters on purification of inclusion bodies, fusion proteins, and purification for crystallography. A purification strategy that can produce a highly pure single protein from a crude mixture of proteins, carbohydrates, lipids, and cell debris to is a work of art to be admired. These books (available individually or as a set)are designed to give the laboratory worker the information needed to undertake the challenge of designing such a strategy.
Book chapters on the topic "Lipid order"
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Gerbeau-Pissot, Patricia, Christophe Der, Markus Grebe, and Thomas Stanislas. "Ratiometric Fluorescence Live Imaging Analysis of Membrane Lipid Order in Arabidopsis Mitotic Cells Using a Lipid Order-Sensitive Probe." In Methods in Molecular Biology, 227–39. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-3142-2_17.
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Makarova, Maria, and Dylan M. Owen. "Quantitative Measurements of Membrane Lipid Order in Yeast and Fungi." In Methods in Molecular Biology, 291–98. New York, NY: Springer US, 2021. http://dx.doi.org/10.1007/978-1-0716-1843-1_22.
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Kunz, Barbara C., Mike Rehorek, and Christoph Richter. "Fluorescence Studies of Lipid Order in Proteoliposomes Containing Cytochrome P-490 and Its Reductase." In Recent Advances in Biological Membrane Studies, 345–58. Boston, MA: Springer US, 1985. http://dx.doi.org/10.1007/978-1-4684-4979-2_20.
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Fuhrer, Andrew, and Amir M. Farnoud. "Characterization of Lipid Order and Domain Formation in Model Membranes Using Fluorescence Microscopy and Spectroscopy." In Methods in Molecular Biology, 271–82. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/978-1-0716-0814-2_15.
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Yordanova, Vesela, Galya Staneva, Plamen Krastev, Tania Markovska, Ana-Mariya Marinovska, Aneliya Kostadinova, Rusina Hazarosova, and Albena Momchilova. "Lipid Order of Membranes Isolated from Erythrocytes of Patients with Coronary Artery Disease: Correlation with Biochemical Parameters." In Recent Contributions to Bioinformatics and Biomedical Sciences and Engineering, 134–46. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-31069-0_14.
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Yamamoto, K., Akira Kamiya, and Joji Ando. "Shear Stress Rapidly Alters the Physical Properties of Vascular Endothelial Cell Membranes by Decreasing Their Lipid Order and Increasing Their Fluidity." In IFMBE Proceedings, 19–22. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-00846-2_4.
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Rinia, Hilde A., George W. H. Wurpel, and Michiel Müller. "Measuring Molecular Order and Orientation Using Coherent Anti-Stokes Raman Scattering Microscopy." In Methods in Membrane Lipids, 45–61. Totowa, NJ: Humana Press, 2007. http://dx.doi.org/10.1007/978-1-59745-519-0_4.
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Van Ginkel, G., L. J. Korstanje, R. Moormans, G. Pruijsen, M. Van Zandvoort, A. A. Van ’T Veld, and Y. K. Levine. "Molecular Order and Dynamics in Membranes Containing α-Tocopherol, (trans 16:3)-Phosphatidyl-Glycerol and other Thylakoid Lipids." In Current Research in Photosynthesis, 1715–18. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0511-5_391.
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Sackmann, E., A. Fischer, and W. Frey. "Polymorphism of Monolayers of Monomeric and Macromolecular Lipids: On the Defect Structure of Crystalline Phases and the Possibility of Hexatic Order Formation." In Springer Proceedings in Physics, 25–37. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-83202-4_5.
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FLORINE-CASTEEL, KATHRYN, JOHN J. LEMASTERS, and BRIAN HERMAN. "Video Imaging of Lipid Order." In Fluorescent and Luminescent Probes for Biological Activity, 628–33. Elsevier, 1999. http://dx.doi.org/10.1016/b978-012447836-7/50048-8.
Full textConference papers on the topic "Lipid order"
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Kumar, G. Aditya, and Manoj A. Puthenveedu. "GPCR cargo modifies lipid order in clathrin-coated pits." In ASPET 2023 Annual Meeting Abstracts. American Society for Pharmacology and Experimental Therapeutics, 2023. http://dx.doi.org/10.1124/jpet.122.158190.
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Schor, Alisha R., and Cullen R. Buie. "Non-Invasive Sorting of Lipid Producing Microalgae With Dielectrophoresis Using Microelectrodes." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-88317.
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In order to advance the algae biofuel industry, we are constructing a dielectrophoretic, single-cell sorter that selects algae based on lipid content. This tool can lower production costs by aiding in strain selection, online culture monitoring, or directed evolution studies. Dielectrophoresis (DEP) is the polarization of particles or cells in a non-uniform electric field, which leads to a Coulomb force on the cell. Lipids and cell cytoplasm have vastly different dielectric properties. Therefore, as a cell accumulates lipid, we predict a change in the overall DEP response. Our models show that in algae culture medium, we should be able to distinguish between high and low lipid content cells at frequencies above 100 MHz. This was confirmed by experiments, in which high and low lipid cultures of Neochloris oleoabundans have DEP crossover frequencies of 190 MHz and 125 MHz, respectively. We have also fabricated a proof-of-concept device validating that cells can be manipulated under DEP. However, in order to achieve sorting, we will require higher frequencies as well as a modified design to eliminate non-uniformities in the electric field through the channel height.
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Yucel, Umut, and Emelie Ivarson. "Analysis of lipid radiolysis in irradiated dried meat products." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/apmz8310.
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Irradiation is a non-thermal process used for preservation and decontamination of human and animal food products. Although irradiation process causes minimal changes to the sensory and nutritional quality, certain irradiation-specific compounds form, such as free radicals and related lipid radiolysis products, which can have organoleptic and health concerns, especially at high doses of 50 kGy or more. For example, radiolysis of palmitic acid-containing lipids typically results in the formation of a unique irradiation marker 2-dodecylcyclobutanone (2-DCB) along with other hydrocarbons (tridecane, 1-tetradecene, tetradecane, 1-pentadecene). Analysis of these irradiation-specific molecules can also be used to back-trace irradiation history of the products. This study involves with the quantitative and mechanistic analysis of the lipid radiolysis products in parallel to changes in the amount of precursor lipid molecules in two dried meat matrixes (e.g., chicken jerkies and pig ears) using SPME-coupled GC-MS analysis. Overall, the formation of rate if 2-DCB was higher (p < 0.05) than hydrocarbons both following zero order kinetics; whereas, the decrease in precursor fatty acids followed first order kinetics. The quantitative analysis requires the use of a suitable internal standard (IS), which can interact with the extraction of the analyte (e.g., 2-DCB) below a critical concentration. This critical concertation was an order of magnitude large in pig ears (>80 ppb) than chicken jerkies (>8 ppb) in parallel to the amount of precursor lipid. Finally, electron paramagnetic resonance spectroscopy was employed complementary to GC-MS analysis, however, providing confirmatory information. The findings of this research help to elucidate the irradiation-specific changes in irradiated meat matrices using an analytical method that also allows quantitative analysis of small sample volumes.
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Hadady, Hanieh, Sage R. Hiibel, Doug Redelman, and Emil J. Geiger. "Use of a Separability Parameter for the Design of a High Frequency Dielectrophoresis Cell Sorter Device." In ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icnmm2015-48528.
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We present a method to quantify and enhance separation of binary cells mixture in the microfluidic device using high frequency dielectrophoresis (>20 MHz). At these frequencies, the DEP response depends primarily on the dielectric properties of the cytoplasm. In order to achieve efficient separation, there must be a difference in the intrinsic dielectric properties of the populations to be sorted. For algae cells, the shift in high frequency dielectrophoresis response during lipid accumulation can be used as a basis of separation. We defined a separability parameter based on the expected difference in the dielectrophoresis responses of the algae cells. Chlamydomonas reinhardtii cells were cultured in regular media and then the same cells were cultured under nitrogenfree conditions to accumulate neutral (non-polar) lipids. Separability of microalgae cells with different lipid content via high frequency dielectrophoresis were investigated by a thin needle shaped electrodes patterned by standard photolithographic and wet etching procedures. Experimental separability factors were measured by estimation of relative lipid content with BODIPY 505/515 fluorescence dye and calculating the area-weighted intensity average of fluorescent images. Theoretical separability parameter was calculated using analytical analysis of single shell model by MATLAB. Theoretical and experimental separability parameters, as tools to determine the optimal separation method, were calculated for microalgae cells with different lipid content. This objective function was maximized in the range of 35–45 MHz for C. reinhardtii cells after 21 days of lipid accumulation in a static separation. In order to design a continuous cell sorter device, the theoretical separation factor was maximized based on differences in the magnitude or the direction of the DEP force.
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Alberdi-Cedeno, Jon, Kubra Demir, and Marc Pignitter. "Influence of monosodium glutamate on the oxidative stability of meat lipids." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/mvhi9556.
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Monosodium glutamate (MSG) is an additive (E621) widely used as flavor enhancer in food industry in order to increase palatability, especially in meat and meat derived products. Its use has increased worldwide by 4.80% during 2017–2021. Therefore, its effect on sensory and organoleptic quality of meat and meat derived products has been extensively investigated. However, so far, studies investigating the impact of MSG on the progress of lipid oxidation in meat are lacking. Therefore, the effect of the fortification of pork burger patties with 0–1.2 % MSG was addressed, paying particular attention to the oxidative stability of their lipids. Samples were storage at 8 °C up to 4 days following oven cooking at 180 °C for 10 min. In order to have an overall view, the samples were analyzed by 1H Nuclear Magnetic Resonance (1H NMR) and Solid Phase Microextraction followed by Gas Chromatography-Mass Spectrometry (SPME-GC-MS). The results showed, for the first time, that the fortification of pork burger patties with MSG caused the degradation of their main polyunsaturated acyl groups, linoleic acyl groups (-6) (p< 0.05), as well as some minor components, such as terpenes, after cooking. The decline of non-oxidized lipids was accompanied by the formation of different oxidation compounds, such as aldehydes, ketones and alcohols among others. In general, the total amount of secondary lipid oxidation compounds was enhanced in the presence of 1.2% MSG compared to the non-treated patties (p< 0.05). Moreover, it was observed that the storage at 8 °C did not have any effects on the oxidative stability of the pork lipids. Overall, MSG was shown to promote lipid oxidation in pork burgers raising concerns about its impact on food quality.
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Prisco, D., P. G. Rogasi, R. Paniccia, A. Panetta, M. Coppo, and G. F. Gensini. "LIPID COMPOSITION OF PLATELETS FROM PATIENTS AFFECTED BY Ila HYPERLIPOPROTEINEMIA." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644568.
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Platelets from patients with familial hypercholesterolemia (IIa HLP), a condition associated with high prevalence of atherosclerosis and of its thrombotic complications, are known to be hyperresponsive to aggregating stimuli and to synthesize increased amounts of thromboxane A2. In order to search if these functional alterations can depend on a different platelet lipid composition, we studied 12 young patients ( aged 20 to 34 years) affected by Ila HLP and 12 suitable controls with similar dietary habits. Lipids were extracted from washed platelets with a chloroform/methanol (2/1) mixture. After silicic acid chromatography and thin-layer chromatography different lipid fractions were eluted and fatty acid methylesters were prepared by acid transmethanolysis. The esters were extracted with hexane and analyzed by gas-liquid chromatography. Different fatty acids were identified on the basis of retention time with respect to standard methylester mixtures and silver nitrate thin-layer chromatography. Cholesterol and lipid phosphorus were assayed by colorimetric methods. Both cholesterol and phospholipid content of platelets were higher in patients than in controls with a significant increase of cholesterol/ phospholipid molar ratio (p<0.05). The percentage content of the phospholipid fractions was not different from that of controls. On the contrary the proportion of saturated fatty acids esterified in the different phospholipid fractions was significantly increased (minimum p<0.05). In addition thromboxane A2 production by platelets from patients with Ila HLP was higher than in controls (<0.001). Our results indicate that lipid composition of platelets from patients with Ila HLP is altered and may be responsible for the enhanced platelet activity described in these patients.
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Gasecka, Alicja, Tsai-Jung Han, Cyril Favard, and Sophie Brasselet. "Quantitative imaging of molecular order in lipid membranes using two-photon fluorescence polarimetry." In Conference on Lasers and Electro-Optics. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/cleo.2010.cthd1.
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Nakano, Takeo, Gota Kikugawa, and Taku Ohara. "Effect of Alkyl Chain Length on Molecular Heat Transfer Characteristics in Lipid Bilayers." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44465.
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Nonequilibrium molecular dynamics simulations are carried out on single component lipid bilayers with ambient water in order to investigate the effect of acyl chain length on heat transport characteristics along and across the membranes. In this study, dipalmitoyl-phosphatidyl-choline (DPPC), dilauroyl-phosphatidyl-choline (DLPC), and stearoyl-myristoyl-phosphatidyl-choline (SMPC) which has two acyl chains of both sixteen C atoms, both twelve C atoms, and eighteen and fourteen C atoms, respectively, were used as lipid molecules. In the direction along the membranes, thermal conductivity corresponds with that of each membrane. On the other hand, in the direction across membrane, the highest thermal resistance exists at the center of lipid bilayer where lipid acyl chains face each other. However, asymmetric chain length reduces thermal resistance at the interface between lipid monolayers. Therefore, thermal conductivity across the membrane which consists of asymmetric chain length is higher than those which consist of symmetric chain length.
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Zeng, Yixiu, Jianling Chen, Hongqin Yang, Yuhua Wang, Hui Li, and Shusen Xie. "Effects of cholesterol on plasma membrane lipid order in MCF-7 cells by two-photon microscopy." In Twelfth International Conference on Photonics and Imaging in Biology and Medicine (PIBM 2014), edited by Qingming Luo, Lihong V. Wang, and Valery V. Tuchin. SPIE, 2014. http://dx.doi.org/10.1117/12.2069100.
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Cancalon, Mathilde, Nathalie Barouh, Youna Hemery, Erwann Durand, Pierre Villeneuve, and Claire Bourlieu-Lacanal. "Lipid Oxidation Kinetics of Model Systems Representative of Follow-on Formulas." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/obji6221.
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The main objective of follow-on formulas is to mimic as closely as possible the composition and structure of mature breast milk. In order to optimize the formulas, important regulatory changes have taken place, including the obligation to supplement the formulas with DHA. The oil phase is therefore formulated from a mixture of oils mainly of vegetable origin with palm oil as the main source of saturated fatty acids and enriched in long-chain polyunsaturated fatty acids. However, these oil blends are not optimal for nutritional needs of infants and are particularly sensitive to lipid oxidation. The aim of this study was to substitute palm oil with other sources of saturated fatty acids in order to ensure a more suitable nutritional profile for infant without impacting or improving stability against lipid oxidation. To reach this objective a model system representative of marketed follow-on formulas was formulated and declined into a panel of model systems depending on the source of saturated fatty acids used. The results showed that depending on the composition of the oil phase the stability against lipid oxidation could be improved. This study has thus highlighted the importance of the balance between nutritional profile and oxidation stability.
Reports on the topic "Lipid order"
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Sukenik, Assaf, Paul Roessler, and John Ohlrogge. Biochemical and Physiological Regulation of Lipid Synthesis in Unicellular Algae with Special Emphasis on W-3 Very Long Chain Lipids. United States Department of Agriculture, January 1995. http://dx.doi.org/10.32747/1995.7604932.bard.
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Various unicellular algae produce omega-3 (w3) very-long-chain polyunsaturated fatty acids (VLC-PUFA), which are rarely found in higher plants. In this research and other studies from our laboratories, it has been demonstrated that the marine unicellular alga Nannochloropsis (Eustigmatophyceae) can be used as a reliable and high quality source for the w3 VLC-PUFA eicosapentaenoic acid (EPA). This alga is widely used in mariculture systems as the primary component of the artificial food chain in fish larvae production, mainly due to its high EPA content. Furthermore, w3 fatty acids are essential for humans as dietary supplements and may have therapeutic benefits. The goal of this research proposal was to understand the physiological and biochemical mechanisms which regulate the synthesis and accumulation of glycerolipids enriched with w3 VLC-PUFA in Nannochloropsis. The results of our studies demonstrate various aspects of lipid synthesis and its regulation in the alga: 1. Variations in lipid class composition imposed by various environmental conditions were determined with special emphasis on the relative abundance of the molecular species of triacylglycerol (TAG) and monogalactosyl diacylglycerol (MGDG). 2. The relationships between the cellular content of major glycerolipids (TAG and MGDG) and the enzymes involved in their synthesis were studied. The results suggested the importance of UDP-galactose diacylglycerol galactosyl (UDGT) in regulation of the cellular level of MGDG. In a current effort we have purified UDGT several hundredfold from Nannochloropsis. It is our aim to purify this enzyme to near homogeneity and to produce antibodies against this enzyme in order to provide the tools for elucidation of the biochemical mechanisms that regulate this enzyme and carbon allocation into galactolipids. 3. Our in vitro and in vivo labeling studies indicated the possibility that phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are associated with desaturation of the structural lipids, whereas shorter chain saturated fatty acids are more likely to be incorporated into TAG. 4. Isolation of several putative mutants of Nannochloropsis which appear to have different lipid and fatty acid compositions than the wild type; a mutant of a special importance that is devoid of EPA was fully characterized. In addition, we could demonstrate the feasibility of Nannochloropsis biomass production for aquaculture and human health: 1) We demonstrated in semi-industrial scale the feasibility of mass production of Nannochloropsis biomass in collaboration with the algae plant NBT in Eilat; 2) Nutritional studies verified the importance algal w3 fatty acids for the development of rats and demonstrated that Nannochloropsis biomass fed to pregnant and lactating rats can benefit their offspring.
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Brown Horowitz, Sigal, Eric L. Davis, and Axel Elling. Dissecting interactions between root-knot nematode effectors and lipid signaling involved in plant defense. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598167.bard.
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Root-knot nematodes, Meloidogynespp., are extremely destructive pathogens with a cosmopolitan distribution and a host range that affects most crops. Safety and environmental concerns related to the toxicity of nematicides along with a lack of natural resistance sources threaten most crops in Israel and the U.S. This emphasizes the need to identify genes and signal mechanisms that could provide novel nematode control tactics and resistance breeding targets. The sedentary root-knot nematode (RKN) Meloidogynespp. secrete effectors in a spatial and temporal manner to interfere with and mimic multiple physiological and morphological mechanisms, leading to modifications and reprogramming of the host cells' functions, resulted in construction and maintenance of nematodes' feeding sites. For successful parasitism, many effectors act as immunomodulators, aimed to manipulate and suppress immune defense signaling triggered upon nematode invasion. Plant development and defense rely mainly on hormone regulation. Herein, a metabolomic profiling of oxylipins and hormones composition of tomato roots were performed using LC-MS/MS, indicating a fluctuation in oxylipins profile in a compatible interaction. Moreover, further attention was given to uncover the implication of WRKYs transcription factors in regulating nematode development. In addition, in order to identify genes that might interact with the lipidomic defense pathway induced by oxylipins, a RNAseq was performed by exposing M. javanicasecond-stage juveniles to tomato protoplast, 9-HOT and 13-KOD oxylipins. This transcriptome generated a total of 4682 differentially expressed genes (DEGs). Being interested in effectors, we seek for DEGs carrying a predicted secretion signal peptide. Among the DEGs including signal peptide, several had homology with known effectors in other nematode species, other unknown potentially secreted proteins may have a role as root-knot nematodes' effectors which might interact with lipid signaling. The molecular interaction of LOX proteins with the Cyst nematode effectors illustrate the nematode strategy in manipulating plant lipid signals. The function of several other effectors in manipulating plant defense signals, as well as lipids signals, weakening cell walls, attenuating feeding site function and development are still being studied in depth for several novel effectors. As direct outcome of this project, the accumulating findings will be utilized to improve our understanding of the mechanisms governing critical life-cycle phases of the parasitic M. incognita RKN, thereby facilitating design of effective controls based on perturbation of nematode behavior—without producing harmful side effects. The knowledge from this study will promote genome editing strategies aimed at developing nematode resistance in tomato and other nematode-susceptible crop species in Israel and the United States.
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Kanner, Joseph, Edwin Frankel, Stella Harel, and Bruce German. Grapes, Wines and By-products as Potential Sources of Antioxidants. United States Department of Agriculture, January 1995. http://dx.doi.org/10.32747/1995.7568767.bard.
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Several grape varieties and red wines were found to contain large concentration of phenolic compounds which work as antioxidant in-vitro and in-vivo. Wastes from wine production contain antioxidants in large amounts, between 2-6% on dry material basis. Red wines but also white wines were found to prevent lipid peroxidation of turkey muscle tissues stored at 5oC. The antioxidant reaction of flavonoids found in red wines against lipid peroxidation were found to depend on the structure of the molecule. Red wine flavonoids containing an orthodihydroxy structure around the B ring were found highly active against LDL and membrane lipid peroxidation. The antioxidant activity of red wine polyphenols were also found to be dependent on the catalyzer used. In the presence of H2O2-activated myoglobin, the inhibition efficiency was malvidin 3-glucoside>catechin>malvidin>resveratol. However, in the presence of an iron redox cycle catalyzer, the order of effectiveness was resveratol>malvidin 3-glucoside = malvidin>catechin. Differences in protein binding were found to affect antioxidant activity in inhibiting LDL oxidation. A model protein such as BSA, was investigated on the antioxidant activity of phenolic compounds, grape extracts, and red wines in a lecithin-liposome model system. Ferulic acid followed by malvidin and rutin were the most efficient in inhibiting both lipid and protein oxidation. Catechin, a flavonal found in red-wines in relatively high concentration was found to inhibit myoglobin catalyzed linoleate membrane lipid peroxidation at a relatively very low concentration. This effect was studied by the determination of the by-products generated from linoleate during oxidation. The study showed that hydroperoxides are catalytically broken down, not to an alcohol but most probably to a non-radical adduct. The ability of wine-phenolics to reduce iron and from complexes with metals were also demonstrated. Low concentration of wine phenolics were found to inhibit lipoxygenase type II activity. An attempt to understand the bioavailability in humans of antocyanins from red wine showed that two antocyanins from red wine were found unchanged in human urine. Other antocyanins seems to undergo molecular modification. In hypercholesterolemic hamsters, aortic lipid deposition was significantly less in animals fed diets supplemented with either catechin or vitamin E. The rate of LDL accumulation in the carotid arteries was also significantly lower in the catechin and vitamin E animal groups. These results suggested a novel mechanism by which wine phenolics are associated with decreased risk of coronary heart diseases. This study proves in part our hypothesis that the "French Paradox" could be explained by the action of the antioxidant effects of phenolic compounds found at high concentration in red wines. The results of this study argue that it is in the interest of public health to increase the consumption of dietary plant falvonoids. Our results and these from others, show that the consumption of red wine or plant derived polyphenolics can change the antioxidant tone of animal and human plasma and its isolated components towards oxidative reactions. However, we need more research to better understand bioavailability and the mechanism of how polyphenolics affect health and disease.
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Colucci, Jose, Govind Nadathur, Vilmaris Bracero, William Rosado, Miriam Fontalvo, Jesus Garcia, Cecilia Diaz, Luis Colon, Adrian Lopez, and Giovanna Santiago. Propulsion and Power Rapid Response Research and Development (R&D) Support. Task Order 0004: Advanced Propulsion Fuels R&D, Subtask: Optimization of Lipid Production and Processing of Microalgae for the Development of Biofuels. Fort Belvoir, VA: Defense Technical Information Center, February 2013. http://dx.doi.org/10.21236/ada582355.
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Handa, Avtar K., Yuval Eshdat, Avichai Perl, Bruce A. Watkins, Doron Holland, and David Levy. Enhancing Quality Attributes of Potato and Tomato by Modifying and Controlling their Oxidative Stress Outcome. United States Department of Agriculture, May 2004. http://dx.doi.org/10.32747/2004.7586532.bard.
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General The final goal and overall objective of the current research has been to modify lipid hydroperoxidation in order to create desirable phenotypes in two important crops, potato and tomato, which normally are exposed to abiotic stress associated with such oxidation. The specific original objectives were: (i) the roles of lipoxygenase (LOX) and phospholipids hydroperoxide glutathione peroxidase (PHGPx) in regulating endogenous levels of lipid peroxidation in plant tissues; (ii) the effect of modified lipid peroxidation on fruit ripening, tuber quality, crop productivity and abiotic stress tolerance; (iii) the effect of simultaneous reduction of LOX and increase of PHGPx activities on fruit ripening and tuber quality; and (iv) the role of lipid peroxidation on expression of specific genes. We proposed to accomplish the research goal by genetic engineering of the metabolic activities of LOX and PHGPx using regulatable and tissue specific promoters, and study of the relationships between these two consecutive enzymes in the metabolism and catabolism of phospholipids hydroperoxides. USA Significant progress was made in accomplishing all objectives of proposed research. Due to inability to regenerate tomato plants after transforming with 35S-PHGPx chimeric gene construct, the role of low catalase induced oxidative stress instead of PHGPx was evaluated on agronomical performance of tomato plant and fruit quality attributes. Effects of polyamine, that protects DNA from oxidative stress, were also evaluated. The transgenic plants under expressing lipoxygenase (LOX-sup) were crossed with catalase antisense (CAT-anti) plants or polyamine over producing plants (SAM-over) and the lines homozygous for the two transgenes were selected. Agronomical performance of these line showed that low catalase induced oxidative stress negatively affected growth and development of tomato plants and resulted in a massive change in fruit gene expression. These effects of low catalase activity induced oxidative stress, including the massive shift in gene expression, were greatly overcome by the low lipoxygenase activity. Collectively results show that oxidative stress plays significant role in plant growth including the fruit growth. These results also for the first time indicated that a crosstalk between oxidative stress and lipoxygenase regulated processes determine the outcome during plant growth and development. Israel Regarding PHGPx, most of the study has concentrated on the first and the last specific objectives, since it became evident that plant transformation with this gene is not obvious. Following inability to achieve efficient transformation of potato and tomato using a variety of promoters, model plant systems (tobacco and potato cell cultures, tobacco calli and plantlets, and Arabidopsis) were used to establish the factors and to study the obstacles which prohibited the regeneration of plants carrying the genetic machinery for overproduction of PHGPx. Our results clearly demonstrate that while genetic transformation and over-expression of PHGPx occurs in pre-developmental tissue stage (cell culture, calli clusters) or in completed plant (Arabidopsis), it is likely that over-expression of this enzyme before tissue differentiation is leading to a halt of the regeneration process. To support this assumption, experiments, in which genetic engineering of a point-mutated PHGPx gene enable transformation and over-expression in plants of PhSPY modified in its catalytic site and thus inactive enzymatically, were successfully carried out. These combined results strongly suggest, that if in fact, like in animals and as we established in vitro, the plant PHGPx exhibits PH peroxidase activity, these peroxides are vital for the organisms developmental process.
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Dickman, Martin B., and Oded Yarden. Regulation of Early Events in Hyphal Elongation, Branching and Differentiation of Filamentous Fungi. United States Department of Agriculture, 2000. http://dx.doi.org/10.32747/2000.7580674.bard.
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In filamentous fungi, hyphal elongation, branching and morphogenesis are in many cases the key to successful saprophytic and pathogenic fungal proliferation. The understanding of the fungal morphogenetic response to environmental cues is in its infancy. Studies concerning the regulation of fungal growth and development (some of which have been obtained by the participating collaborators in this project) point to the fact that ser/thr protein kinases and phosphatases are (i) involved in the regulation of such processes and (ii) share common structural and functional features between saprophytes and pathogens. It is our objective to combine a pharmaceutical and a genetic approach in order to identify, characterize and functionally dissect some of the regulatory factors involved in hyphal growth, branching and differentiation. Using an immunohistochemical approach, a ser/thr protein kinase involved in hyphal elongation in both Neurospora crassa and Colletotrichum trifolii has been localized in order to identify the physical arena of regulation of hyphal elongation. The analysis of additional kinases and phosphatases (e.g. Protein kinase C, cAMP-dependent kinase, lipid-activated protein kinase, components of the type 2A protein phosphatase) as well as a RAS-related gene (an additional key participant in signal transduction) has been performed. In order to succeed in advancing the goals of this project, we have taken advantage of available elongation/branching mutants in N. crassa and continuously combined the accumulated information obtained while studying the two systems in order to dissect the elements involved in these processes. The various inhibitors/effectors analyzed can serve as a basis for modification to be used as anti-fungal compounds. Understanding the regulation of hyphal proliferation is a key requirement for identifying novel target points for either curbing fungal growth (as in the case of pathogenesis) or affecting growth patterns in various biotechnological processes. The major objective of our joint project was to advance our understanding of regulation of hyphal growth, especially during early events of fungal germination. Towards achieving this goal, we have coupled the analysis of a genetically tractable organism (N. crassa) with a plant pathogen o economic importance (C. trifolii). As the project progressed we believe that the results obtained have provided a reinforcement to our basic approach which called for combining the two fungal systems for a joint research project. On the one hand, we feel that much of the advance made was possible due to the amenability of N. crassa to genetic manipulations. The relevance of some of the initial findings obtained in Neurospora have been proven to be relevant to the plant pathogen while unique features of the pathogen have been identified in Colletotrichum. Most of the results obtained from this research project have been published. Thus, the main volume of this report is comprised of the relevant publications describing the research and results obtained.
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O'Neill, Sharman, Abraham Halevy, and 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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Keshav, Dr Geetha, Dr Suwaibah Fatima Samer, Dr Salman Haroon, and Dr Mohammed Abrar Hassan. TO STUDY THE CORRELATION OF BMI WITH ABO BLOOD GROUP AND CARDIOVASCULAR RISK AMONG MEDICAL STUDENTS. World Wide Journals, February 2023. http://dx.doi.org/10.36106/ijar/2405523.
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Introduction: Advancements and increase in access to healthcare have increased the life expectancy in India from 32 years in 1947 to almost 70 years currently. Due to robust vaccination and basic health programs, most of the communicable diseases are kept under control. The disease burden is now skewed towards non-communicable diseases. It is an established fact that body mass index (BMI) is a reliable predictor of cardiovascular disease (CVD) later in life. Early prediction can decrease the disease load and enable early preventative measures. A more novel approach of connecting it with blood groups would yield profound results in predictability and subsequent management. This study was done to see correlation between BMI and known blood groups in order to predict the potential incidence of CVDs in medical students. Material and Method - A cross-sectional descriptive study was conducted in Bhaskar Medical College from September 2022 - November 2022. The sample population included 150- 1st year medical students chosen by Randomized sampling method. BMI was calculated based as weight in kilograms divided by the square of the height in meters (kg/m2). Discussion - Many studies conducted on the association of Blood groups with BMI yielded mixed and inconclusive results. On analysis of the data obtained from this study, O- positive blood group showed the highest inclination towards obesity i.e. 30 of the total participants. A-positive and B- positive blood groups were shown to have a lesser association with obesity i.e. 11 participants of the 150. These results were in accordance with a study done among female students by Shireen Javad et.al, nding blood group O to be the most prone to obesity.8 Incompatible to our results, a study conducted by Samuel Smith Isaac Okai et.al. found no signicant association between blood groups and BMI.10 Another study conducted by Christina Ravillo et.al. found that blood group O had the highest and blood group AB with lowest prevalence of obesity9. These ndings were similar to the results obtained in our study. To study the correlation of BMI with ABO blood group and Cardiovascula AIMS and OBJECTIVES Aim: - r risk among medical students. 1. Calculate and segregate the participants according to BM Objectives: - I using the standard formula provided by the WHO. 1. Determine Blood group using antisera 2. Evaluation of Lipid prole in obese individuals
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McClure, Michael A., Yitzhak Spiegel, David M. Bird, R. Salomon, and R. H. C. Curtis. Functional Analysis of Root-Knot Nematode Surface Coat Proteins to Develop Rational Targets for Plantibodies. United States Department of Agriculture, October 2001. http://dx.doi.org/10.32747/2001.7575284.bard.
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The goal of this research was to provide a better understanding of the interface between root-knot nematodes, Meloidogyne spp., and their host in order to develop rational targets for plantibodies and other novel methods of nematode control directed against the nematode surface coat (SC). Specific objectives were: 1. To produce additional monoclonal SC antibodies for use in Objectives 2, 3, and 4 and as candidates for development of plantibodies. 2. To determine the production and distribution of SC proteins during the infection process. 3. To use biochemical and immunological methods to perturbate the root-knot nematode SC in order to identify SC components that will serve as targets for rationally designed plantibodies. 4. To develop SC-mutant nematodes as additional tools for defining the role of the SC during infection. The external cuticular layer of nematodes is the epicuticle. In many nematodes, it is covered by a fuzzy material termed "surface coat" (SC). Since the SC is the outermost layer, it may playa role in the interaction between the nematode and its surroundings during all life stages in soil and during pathogenesis. The SC is composed mainly of proteins, carbohydrates (which can be part of glycoproteins), and lipids. SC proteins and glycoproteins have been labeled and extracted from preparasitic second-stage juveniles and adult females of Meloidogyne and specific antibodies have been raised against surface antigens. Antibodies can be used to gain more information about surface function and to isolate genes encoding for surface antigens. Characterization of surface antigens and their roles in different life-stages may be an important step towards the development of alternative control. Nevertheless, the role of the plant- parasitic nematode's surface in plant-nematode interaction is still not understood. Carbohydrates or carbohydrate-recognition domains (CROs) on the nematode surface may interact with CROs or carbohydrate molecules, on root surfaces or exudates, or be active after the nematode has penetrated into the root. Surface antigens undoubtedly play an important role in interactions with microorganisms that adhere to the nematodes. Polyclonal (PC) and monoclonal (MC) antibodies raised against Meloidogyne javanica, M. incognita and other plant-parasitic nematodes, were used to characterize the surface coat and secreted-excreted products of M. javanica and M. incognita. Some of the MC and PC antibodies raised against M. incognita showed cross-reactivity with the surface coat of M. javanica. Further characterization, in planta, of the epitopes recognized by the antibodies, showed that they were present in the parasitic juvenile stages and that the surface coat is shed during root penetration by the nematode and its migration between root cells. At the molecular level, we have followed two lines of experimentation. The first has been to identify genes encoding surface coat (SC) molecules, and we have isolated and characterized a small family of mucin genes from M. incognita. Our second approach has been to study host genes that respond to the nematode, and in particular, to the SC. Our previous work has identified a large suite of genes expressed in Lycopersicon esculentum giant cells, including the partial cDNA clone DB#131, which encodes a serine/threonine protein kinase. Isolation and predicted translation of the mature cDNA revealed a frame shift mutation in the translated region of nematode sensitive plants. By using primers homologous to conserved region of DB#131 we have identified the orthologues from three (nematode-resistant) Lycopersicon peruvianum strains and found that these plants lacked the mutation.