Academic literature on the topic 'Spatial organiser of signalling'
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Journal articles on the topic "Spatial organiser of signalling"
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Kilpatrick, Laura E., and Stephen J. Hill. "The use of fluorescence correlation spectroscopy to characterise the molecular mobility of G protein-coupled receptors in membrane microdomains: an update." Biochemical Society Transactions 49, no. 4 (August 26, 2021): 1547–54. http://dx.doi.org/10.1042/bst20201001.
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It has become increasingly apparent that some G protein-coupled receptors (GPCRs) are not homogeneously expressed within the plasma membrane but may instead be organised within distinct signalling microdomains. These microdomains localise GPCRs in close proximity with other membrane proteins and intracellular signalling partners and could have profound implications for the spatial and temporal control of downstream signalling. In order to probe the molecular mechanisms that govern GPCR pharmacology within these domains, fluorescence techniques with effective single receptor sensitivity are required. Of these, fluorescence correlation spectroscopy (FCS) is a technique that meets this sensitivity threshold. This short review will provide an update of the recent uses of FCS based techniques in conjunction with GPCR subtype selective fluorescent ligands to characterise dynamic ligand–receptor interactions in whole cells and using purified GPCRs.
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Robertson, Elizabeth J., Dominic P. Norris, Jane Brennan, and Elizabeth K. Bikoff. "Control of early anterior-posterior patterning in the mouse embryo by TGF-β signalling." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 358, no. 1436 (August 29, 2003): 1351–58. http://dx.doi.org/10.1098/rstb.2003.1332.
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Prior to gastrulation the mouse embryo exists as a symmetrical cylinder consisting of three tissue layers. Positioning of the future anterior–posterior axis of the embryo occurs through coordinated cell movements that rotate a pre–existing proximal–distal (P–D) axis. Overt axis formation becomes evident when a discrete population of proximal epiblast cells become induced to form mesoderm, initiating primitive streak formation and marking the posterior side of the embryo. Over the next 12–24 h the primitive streak gradually elongates along the posterior side of the epiblast to reach the distal tip. The most anterior streak cells comprise the ‘organizer’ region and include the precursors of the so–called ‘axial mesendoderm’, namely the anterior definitive endoderm and prechordal plate mesoderm, as well as those cells that give rise to the morphologically patent node. Signalling pathways controlled by the transforming growth factor–β ligand nodal are involved in orchestrating the process of axis formation. Embryos lacking nodal activity arrest development before gastrulation, reflecting an essential role for nodal in establishing P–D polarity by generating and maintaining the molecular pattern within the epiblast, extraembryonic ectoderm and the visceral endoderm. Using a genetic strategy to manipulate temporal and spatial domains of nodal expression reveals that the nodal pathway is also instrumental in controlling both the morphogenetic movements required for orientation of the final axis and for specification of the axial mesendoderm progenitors.
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Galli-Resta, L. "Local, possibly contact-mediated signalling restricted to homotypic neurons controls the regular spacing of cells within the cholinergic arrays in the developing rodent retina." Development 127, no. 7 (April 1, 2000): 1509–16. http://dx.doi.org/10.1242/dev.127.7.1509.
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In the vertebrate retina neurons of the same type commonly form non-random arrays, assembled by unknown positional mechanisms during development. Computational models in which no two cells are closer than a minimal distance, simulate many retinal arrays. These findings have important biological implications, since they suggest that cells are determined as neurons of specific types before entering their arrays, and that local, possibly contact-mediated interactions acting exclusively among the elements of an array account for its assembly. This is here verified by combining experimental manipulations in normal and transgenic models with computational analysis for the cholinergic mosaics, the only arrays so far for which the development of spatial ordering is known quantitatively. When generalised, these findings suggest a plan for vertebrate retinal patterning, where homotypic interactions organise retinal arrays first, then local interactions between synaptic partners suffice to establish the topographical connections that support retinal processing.
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Yasuo, Hitoyoshi, and Patrick Lemaire. "Role of Goosecoid, Xnot and Wnt antagonists in the maintenance of the notochord genetic programme in Xenopus gastrulae." Development 128, no. 19 (October 1, 2001): 3783–93. http://dx.doi.org/10.1242/dev.128.19.3783.
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The Xenopus trunk organiser recruits neighbouring tissues into secondary trunk axial and paraxial structures and itself differentiates into notochord. The inductive properties of the trunk organiser are thought to be mediated by the secretion of bone morphogenetic protein (BMP) antagonists. Ectopic repression of BMP signals on the ventral side is sufficient to mimic the inductive properties of the trunk organiser. Resultant secondary trunks contain somite and neural tube, but no notochord. We show that inhibition of BMP signalling is sufficient for the initiation of the trunk organiser genetic programme at the onset of gastrulation. During late gastrulation, however, this programme is lost, due to an invasion of secreted Wnts from neighbouring tissues. Maintenance of this programme requires co-repression of BMP and Wnt signalling within the presumptive notochord region. To shed light on the molecular cascade that leads to the repression of the Wnt pathway, we looked for individual organiser genes whose overexpression could complement the inhibition of BMP signalling to promote notochord formation in the secondary trunks. Two genes, gsc and Xnot, were thus identified and shown to act in different ways. Xnot acts as a transcriptional repressor within the mesodermal region. Gsc acts in deeper vegetal cells, where it regulates Frzb expression to maintain Xnot expression in the neighbouring notochord territory. These results suggest that, during gastrulation, the necessary repression of Wnt/β-catenin signalling in notochord precursors is achieved by the action of secreted inhibitors, such as Frzb, emitted by gsc-expressing dorsal vegetal cells.
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Crozatier, Michèle, Bruno Glise, and Alain Vincent. "Connecting Hh, Dpp and EGF signalling in patterning of theDrosophilawing; the pivotal role ofcollier/knotin the AP organiser." Development 129, no. 18 (September 15, 2002): 4261–69. http://dx.doi.org/10.1242/dev.129.18.4261.
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Hedgehog (Hh) signalling from posterior (P) to anterior (A) cells is the primary determinant of AP polarity in the limb field in insects and vertebrates. Hh acts in part by inducing expression of Decapentaplegic (Dpp), but how Hh and Dpp together pattern the central region of the Drosophila wing remains largely unknown. We have re-examined the role played by Collier (Col), a dose-dependent Hh target activated in cells along the AP boundary, the AP organiser in the imaginal wing disc. We found that col mutant wings are smaller than wild type and lack L4 vein, in addition to missing the L3-L4 intervein and mis-positioning of the anterior L3 vein. We link these phenotypes to col requirement for the local upregulation of both emc and N, two genes involved in the control of cell proliferation, the EGFR ligand Vein and the intervein determination gene blistered. We further show that attenuation of Dpp signalling in the AP organiser is also col dependent and, in conjunction with Vein upregulation, required for formation of L4 vein. A model recapitulating the molecular interplay between the Hh, Dpp and EGF signalling pathways in the wing AP organiser is presented.
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Tossell, K., C. Kiecker, A. Wizenmann, E. Lang, and C. Irving. "Notch signalling stabilises boundary formation at the midbrain-hindbrain organiser." Development 138, no. 17 (July 27, 2011): 3745–57. http://dx.doi.org/10.1242/dev.070318.
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Carl, M., and J. Wittbrodt. "Graded interference with FGF signalling reveals its dorsoventral asymmetry at the mid-hindbrain boundary." Development 126, no. 24 (December 15, 1999): 5659–67. http://dx.doi.org/10.1242/dev.126.24.5659.
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Signalling by fibroblast growth factors (FGFs) at the mid-hindbrain boundary (MHB) is of central importance for anteroposterior neural patterning from the isthmic organiser. Graded suppression of FGF signalling by increasing amounts of a dominant negative FGF receptor provides evidence that in addition to anteroposterior patterning, FGF signalling is also involved in patterning along the dorsoventral axis at the MHB. FGF signalling at the MHB is required for the activation of the HH target gene spalt at the MHB. Our results indicate that FGF signalling mediates the competence of the MHB to activate spalt in response to SHH. This interdependence of the two signalling pathways is also found in the outbudding optic vesicle where HH requires functional FGF signalling to activate spalt in the proximal eye region.
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Sykes, T. G., A. R. Rodaway, M. E. Walmsley, and R. K. Patient. "Suppression of GATA factor activity causes axis duplication in Xenopus." Development 125, no. 23 (December 1, 1998): 4595–605. http://dx.doi.org/10.1242/dev.125.23.4595.
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In Xenopus, the dorsoventral axis is patterned by the interplay between active signalling in ventral territories, and secreted antagonists from Spemann's organiser. Two signals are important in ventral cells, bone morphogenetic protein-4 (BMP-4) and Wnt-8. BMP-4 plays a conserved role in patterning the vertebrate dorsoventral axis, whilst the precise role of Wnt-8 and its relationship with BMP-4, are still unclear. Here we have investigated the role played by the GATA family of transcription factors, which are expressed in ventral mesendoderm during gastrulation and are required for the differentiation of blood and endodermal tissues. Injection ventrally of a dominant-interfering GATA factor (called G2en) induced the formation of secondary axes that phenocopy those induced by the dominant-negative BMP receptor. However, unlike inhibiting BMP signalling, inhibiting GATA activity in the ectoderm does not lead to neuralisation. In addition, analysis of gene expression in G2en injected embryos reveals that at least one known target gene for BMP-4, the homeobox gene Vent-2, is unaffected. In contrast, the expression of Wnt-8 and the homeobox gene Vent-1 is suppressed by G2en, whilst the organiser-secreted BMP antagonist chordin becomes ectopically expressed. These data therefore suggest that GATA activity is essential for ventral cell fate and that subsets of ventralising and dorsalising genes require GATA activity for their expression and suppression, respectively. Finally, using G2en, we show that suppression of Wnt-8 expression, in conjunction with blocked BMP signalling, does not lead to head formation, suggesting that the head-suppressing Wnt signal may not be Wnt-8.
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Carnac, G., L. Kodjabachian, J. B. Gurdon, and P. Lemaire. "The homeobox gene Siamois is a target of the Wnt dorsalisation pathway and triggers organiser activity in the absence of mesoderm." Development 122, no. 10 (October 1, 1996): 3055–65. http://dx.doi.org/10.1242/dev.122.10.3055.
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Siamois, a Xenopus zygotic homeobox gene with strong dorsalising activity, is expressed in the dorsal-vegetal organiser known as the Nieuwkoop centre. We show that, in contrast to Spemann organiser genes such as goosecoid, chordin and noggin, Siamois gene expression is not induced following overexpression of mesoderm inducers in ectodermal (animal cap) cells. However, Siamois is induced by overexpressing a dorsalising Wnt molecule. Furthermore, like Wnt, Siamois can dorsalise ventral mesoderm and cooperate with Xbrachyury to generate dorsal mesoderm. These results suggest that Siamois is a mediator of the Wnt-signalling pathway and that the synergy between the Wnt and mesoderm induction pathways occurs downstream of the early target genes of these two pathways. Overexpression of Siamois in animal cap cells reveals that this gene can act in a non vegetal or mesodermal context. We show the following. (1) Animal cap cells overexpressing Siamois secrete a factor able to dorsalise ventral gastrula mesoderm in tissue combination experiments. (2) The Spemann organiser-specific genes goosecoid, Xnr-3 and chordin, but not Xlim.1, are activated in these caps while the ventralising gene Bmp-4 is repressed. However, the dorsalising activity of Siamois-expressing animal caps is significantly different from that of noggin- or chordin-expressing animal caps, suggesting the existence of other dorsalising signals in the embryo. (3) Ectodermal cells overexpressing Siamois secrete a neuralising signal and can differentiate into cement gland and, to a lesser extent, into neural tissue. Hence, in the absence of mesoderm induction, overexpression of Siamois is sufficient to confer organiser properties on embryonic cells.
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Monterisi, Stefania, and Manuela Zaccolo. "Components of the mitochondrial cAMP signalosome." Biochemical Society Transactions 45, no. 1 (February 8, 2017): 269–74. http://dx.doi.org/10.1042/bst20160394.
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3′-5′-Cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signalling is activated by different extracellular stimuli and mediates many diverse processes within the same cell. It is now well established that in order to translate into the appropriate cellular function multiple extracellular inputs, which may act simultaneously on the same cell, the cAMP/PKA signalling pathway is compartmentalised. Multimolecular complexes are organised at specific subcellular sites to generate spatially confined signalosomes, which include effectors, modulators and targets of the pathway. In recent years, it has become evident that mitochondria represent sites of compartmentalised cAMP signalling. However, the exact location and the molecular composition of distinct mitochondria signalosomes and their function remain largely unknown. In this review, we focus on individual components of the cAMP/PKA signalling pathway at distinct mitochondria subdomains represented by the outer and inner mitochondrial membranes, the intermembrane space and the matrix, highlighting some of the questions that remain unanswered.
Dissertations / Theses on the topic "Spatial organiser of signalling"
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Lee, Sue Chin. "Spatial signalling of phosphatidic acid." Thesis, University of Strathclyde, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.510804.
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Barrow, Rachel Jenny Mary. "Spatial signalling of Met in cancer." Thesis, Queen Mary, University of London, 2012. http://qmro.qmul.ac.uk/xmlui/handle/123456789/3364.
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Met, the receptor of Hepatocyte Growth Factor, is a receptor tyrosine kinase (RTK) overexpressed or mutated in cancer. RTKs have been increasingly recognised to signal post-endocytosis, possibly leading to unique consequences on cellular outcome due to the spatial and temporal activation of downstream signalling pathways. The objectives of my study were to investigate the role of Met “endosomal signalling” in cancer progression. I found, using four human breast cell lines, that the requirement of Met endocytosis for Met signalling as well as Met trafficking significantly vary with the cells’ aggressiveness, suggesting Met resides longer on endosomes in invasive cells. Furthermore Met endosomal localisation increases with the progression of breast cancer of human samples. Our study suggests that the endosomal location of Met is important in breast cancer progression. I used a model of Wt and two Met oncogenic mutants, M1268T and D1246N, expressed in NIH3T3 fibroblasts. I determined some mechanisms regulating the constitutive endocytosis and defect in degradation of the mutants. I established that targeting these mechanisms could be used to reduce Met mutants’ tumourigenicity. Thus impairing c-Cbl or Grb2 expression and/or binding to Met mutant or restoring Met mutant degradation through inhibiting the chaperone protein HSP90, greatly reduced the transforming capacities of the mutants in vitro and in vivo, including the D1246N that I show to be resistant to small molecule Met inhibitors.
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McKay, Sean. "Probing spatial and subunit-dependent signalling by the NMDA receptor." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/14225.
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NMDARs are ligand-gated cation channels which are activated by the neurotransmitter glutamate. NMDARs are essential in coupling electrical activity to biochemical signalling as a consequence of their high Ca2+ permeability. This Ca2+ influx acts as a secondary messenger to mediate neurodevelopment, synaptic plasticity, neuroprotection and neurodegeneration. The biological outcome of NMDAR activation is determined by a complicated interrelationship between the concentration of Ca2+ influx, NMDAR location (synaptic vs. extrasynaptic) as well as the subtype of the GluN2 subunit. Despite the recognition that NMDAR mediated physiology is multifaceted, tools used to study subunit and location dependent signalling are poorly characterized and in other cases, non-existent. Therefore, the aim of this thesis is to address this issue. Firstly, I assessed the current pharmacological approach used to selectively activate extrasynaptic NMDARs. Here, synaptic NMDARs are first blocked with MK-801 during phasic activation and then extrasynaptic NMDARs are tonically activated. This approach relies on the continual irreversible blockade of synaptic NMDARs by MK-801 yet contrary to the current dogma, I demonstrate this blockade is unstable during tonic agonist exposure and even more so when physiologically relevant concentrations of Mg2+ are present. This confines a temporal limit in which selective activation of extrasynaptic NMDARs can occur with significant consequences for studying synaptic vs. extrasynaptic NMDAR signalling. Dissecting subunit-dependent signalling mediated by the two major GluN2 subunits in the forebrain, GluN2A and GluN2B, has been advanced significantly by selective GluN2B antagonism yet a reciprocal GluN2A selective antagonist has been lacking. Utilizing novel GluN2A-specific antagonists, I demonstrate a developmental upregulation of GluN2A-mediated NMDA currents which concurrently dilutes the contribution of GluN2B-mediated currents. Moreover, I tested the hypothesis that the Cterminus of GluN2A and GluN2B are essential in controlling the developmental switch of GluN2 subunits utilizing knock-in mice whereby the C-terminus of GluN2A is replaced with that of GluN2B. Surprisingly, the exchange of the C-terminus does not impede the developmental switch in subunits nor the proportion of NMDARs at synaptic vs extrasynaptic sites. However, replacing the C-terminus of GluN2A with that of GluN2B induces a greater neuronal vulnerability to NMDA-dependent excitotoxicity. Collectively, this work enhances our understanding of the complex physiology mediated by the NMDAR by determining how pharmacological tools are best utilized to study the roles of NMDAR location and subunit composition in addition to revealing the importance of the GluN2 C-terminus in development and excitotoxicity.
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Shimizu, Thomas Simon. "The spatial organisation of cell signalling pathways - a computer-based study." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620667.
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Reichert, S. "The dynamic temporal and spatial regulation of BMP signalling during early vertebrate development." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1420539/.
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During embryonic development multipotent cells are specified to give rise to the different tissues of the body. This process depends on a tightly controlled network of signalling pathways. Importantly, tissues, which require differential activity of these pathways, can be induced in close proximity, thus suggesting an intricate spatial and temporal control of pathway activation. One of the pathways crucial for tissue specification is the bone morphogenetic protein (BMP) signalling pathway. Its role in the patterning of the ectoderm is well understood during gastrulation but unclear for later stages of development. Using zebrafish and Xenopus as model organisms, I investigated the spatial and temporal control of BMP activity after gastrulation at the border of the neural plate as progenitor cells emerge that give rise to cell types such as melanocytes and smooth muscle cells, as well as the olfactory epithelium and the lens. I identified new players that regulate the formation of distinct domains of BMP signalling and thereby enable the specification of adjacent tissues with different requirements for BMP activity. Previously, Snw1 was identified as a crucial factor for neural crest specification during development. Overexpression and depletion of Snw1 in Xenopus and zebrafish embryos leads to a loss of the neural crest cell population. Snw1 was identified as a regulator of BMP activity at the neural plate border, but not as a core component of the pathway downstream of the receptor. Snw1 is involved in a step between transcription and expression of the BMP ligands and since depletion of Snw1 in zebrafish increases bmp2b ligand transcription but prevents expression of the protein. I have further dissected the function of Snw1 and shown that Snw1 is in a complex with components of splicing machinery, as well as several chromatin remodeling and transcriptional elongation factors. I have used RNAseq to identify additional Snw1 targets.
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Owen, Markus Roger. "Mathematical modelling of the macrophage invasion of tumours and juxtacrine signalling in epidermal wound healing." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344031.
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Heinelt, Kaatje Friederike [Verfasser], Philippe [Akademischer Betreuer] Bastiaens, and Leif [Gutachter] Dehmelt. "Systems analysis of the spatial regulation of oncogenic Ras signalling / Kaatje Friederike Heinelt ; Gutachter: Leif Dehmelt ; Betreuer: Philippe Bastiaens." Dortmund : Universitätsbibliothek Dortmund, 2017. http://d-nb.info/1136471596/34.
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Abu-alhiga, Rami. "Novel feedback and signalling mechanisms for interference management and efficient modulation." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/4632.
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In order to meet the ever-growing demand for mobile data, a number of different technologies have been adopted by the fourth generation standardization bodies. These include multiple access schemes such as spatial division multiple access (SDMA), and efficient modulation techniques such as orthogonal frequency division multiplexing (OFDM)-based modulation. The specific objectives of this theses are to develop an effective feedback method for interference management in smart antenna SDMA systems and to design an efficient OFDM-based modulation technique, where an additional dimension is added to the conventional two-dimensional modulation techniques such as quadrature amplitude modulation (QAM). In SDMA time division duplex (TDD) systems, where channel reciprocity is maintained, uplink (UL) channel sounding method is considered as one of the most promising feedback methods due to its bandwidth and delay efficiency. Conventional channel sounding (CCS) only conveys the channel state information (CSI) of each active user to the base station (BS). Due to the limitation in system performance because of co-channel interference (CCI) from adjacent cells in interference-limited scenarios, CSI is only a suboptimal metric for multiuser spatial multiplexing optimization. The first major contribution of this theses is a novel interference feedback method proposed to provide the BS with implicit knowledge about the interference level received by each mobile station (MS). More specifically, it is proposed to weight the conventional channel sounding pilots by the level of the experienced interference at the user’s side. Interference-weighted channel sounding (IWCS) acts as a spectrally efficient feedback technique that provides the BS with implicit knowledge about CCI experienced by each MS, and significantly improves the downlink (DL) sum capacity for both greedy and fair scheduling policies. For the sake of completeness, a novel procedure is developed to make the IWCS pilots usable for UL optimization. It is proposed to divide the optimization metric obtained from the IWCS pilots by the interference experienced at the BS’s antennas. The resultant new metric, the channel gain divided by the multiplication of DL and UL interference, provides link-protection awareness and is used to optimize both UL and DL. Using maximum capacity scheduling criterion, the link-protection aware metric results in a gain in the median system sum capacity of 26.7% and 12.5% in DL and UL respectively compared to the case when conventional channel sounding techniques are used. Moreover, heuristic algorithm has been proposed in order to facilitate a practical optimization and to reduce the computational complexity. The second major contribution of this theses is an innovative transmission approach, referred to as subcarrier-index modulation (SIM), which is proposed to be integrated with OFDM. The key idea of SIM is to employ the subcarrier-index to convey information to the receiver. Furthermore, a closed-form analytical bit error ratio (BER) of SIM OFDM in Rayleigh channel is derived. Simulation results show BER performance gain of 4 dB over 4-QAM OFDM for both coded and uncoded data without power saving policy. Alternatively, power saving policy maintains an average gain of 1 dB while only using half OFDM symbol transmit power.
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Smallman, Matthew John. "Spatial regulation of Rho GTPase signalling during root hair development in Arabidopsis thaliana is reliant upon the guanine nucleotide dissociation inhibitor SCN1." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496221.
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The scn1-1 mutants of Arabidopsis are characterised by spatially deregulated sites of root hair growth. This studydemonstrates that this phenotype is the result of the loss of regulation of members of the plant specific sub-family of Rho small GTPases by the Guanine nucleotide Dissociation Inhibitor (GDI), encoded by SCN1. The small GTPases R0P2, R0P4 and R0P5 of Arabidopsis are members of the I subset of type I ROPs that terminate with a conserved CXXL box and undergo 3 prenylation. These small GTPases are expressed in trichoblasts, and localize in patters suggestive of specific roles throughout root hair development. Loss-of function ROP2, R0P4 or ROP5 mutants display distinct root hair phenotypes lending support to the hypothesis that : R0P2, R0P4 and ROP5 control the establishment of the site of root hair initiation and subsequent tip-growth. Our findings also reveal SCNl/GDIl and R0P2 co-localize in a similiar pattern in developing root hairs in planta, but SCNl/GDIl is able to associate directly with ROP2, ROP4 and ROP5 in vitro.This suggests root hair morphogenesis relies on the negative regulation of ROP activity by SCNl/GDI 1 and is further supported by morphological phenotypes of scnl-l plants which can be rescued by the over expression of CFP:GD11 fusion placed under the control of the root hair specific PRP3 (Proline Rich Protein3) promoter. These observations imply that ROPs can be selectively sequestered away from the from plasma membrane of elongating root hairs during tip growth thereby promoting growth along a planar axis. Differences in the observed binding affinity of R0P2 in comparison to R0P4 and ROPS for SCNl/GDIl provides evidence that the CXXL box may play a critical role in ROP regulation, and that R0P2 and R0P4 are differentially prenylated.
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Alam, Nazki Aiman. "Elucidating the spatial organization and control of information processing in cell signalling networks : from network and enzymatic building blocks to concrete systems." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/29945.
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Cells function and survive by making decisions in response to dynamic environments. The core controllers of decision-making are highly complex intracellular networks of proteins and genes, which harbour sophisticated information processing capabilities. The effect of spatial organization and control of signaling networks is typically ignored. However, the role of space in signalling networks is being increasingly recognized. While there are some experimental and modelling efforts that incorporate spatial aspects in specific cellular contexts, the role of spatial regulation of signalling across different cell networks remains largely unexplored. In this thesis, we utilize a combination of mathematical modeling, systems engineering and in silico synthetic approaches to understand the spatial organization and control of signaling networks at multiple levels. We examine spatial effects in representative networks and enzymatic building blocks, including typical network modules, covalent modification cycles and enzymatic modification cascades and pathways. We complement these studies by dissecting the role of spatial regulation in the concrete context of the Caulobacter cell cycle, which involves specific combinations of these building blocks. In another investigation, we examine the organization of spatially regulated signaling networks underlying chemotaxis. We explicitly examine the effects of diffusion and its interplay with spatially varying signals and localization/compartmentalization of signalling entities and gain key insights into the interplay of these factors. At the network level, examining typical network modules reveals how introduction of diffusion/global entities may significantly distort temporal characteristics and introduce new types of signal transduction characteristics. At the enzymatic level, dissecting spatial regulation in enzymatic modules highlights the subtle effect and new facets that arise due to the interweaving of cycle kinetics and diffusion. The various ways in which spatial compartmentalization affects pathway behaviour is revealed in the study of various types of signaling pathways. The study of spatial regulation of these enzymatic/network building blocks provides a systematic basis for understanding how spatial control can affect the spatiotemporal interactions driving Caulobacter cell cycle and we use an in-silico synthetic approach to create a platform for further understanding the functioning of the networks controlling this process. In a different study, we use a design approach to shed light on different signalling configurations of chemotactic networks that allow cells to exhibit both attractive and repulsive behaviour, in light of known signalling characteristics seen in cells. Our results uncover the various capabilities, constraints and trade-offs associated with the spatial control of information processing in signalling networks, which come to the surface only if spatial factors are explicitly considered. Overall, using a focused multipronged approach reveals different facets of spatial regulation of signalling at multiple levels and in different contexts. Combining mathematical modelling, systems engineering and synthetic design approaches creates a powerful framework, which may be used to elucidate spatial control of information processing in multiple contexts and design synthetic systems that could fruitfully exploit spatial organization and regulation.
Book chapters on the topic "Spatial organiser of signalling"
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Augustine, George J., Elizabeth A. Finch, and Samuel S. H. Wang. "The Spatial Range of Dendritic Signals for Cerebellar Long-Term Depression." In Integrative Aspects of Calcium Signalling, 311–31. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4899-1901-4_15.
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Monk, N. "Spatial Patterning in Explicitly Cellular Environments: Activity-Regulated Juxtacrine Signalling." In Natural Computing Series, 211–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-662-06369-9_11.
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Wu, Qian, Lynn Sibanda, Takashi Ochi, Victor M. Bolanos-Garcia, Tom L. Blundell, and Dimitri Y. Chirgadze. "Spatial and Temporal Organisation of Multiprotein Systems of Cell Regulation and Signalling: What Can We Learn from NHEJ System of Double-Strand Break Repair?" In Macromolecular Crystallography, 1–31. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2530-0_1.
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Sharp, Trevor. "Neurotransmitters and signalling." In New Oxford Textbook of Psychiatry, edited by John R. Geddes, Nancy C. Andreasen, and Guy M. Goodwin, 122–34. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780198713005.003.0014.
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Chemical transmission at brain synapses is critical to neuronal signalling, and when it goes wrong, psychiatric or neurological disorder likely ensues. Chemical transmission was once considered to involve a simple ‘forward-direction’, on–off signal generated through the interaction between one of a small number of neurotransmitter molecules and their receptor. This concept has evolved to the synapse being viewed as an extremely complex chemical machine that utilizes a vast array of neurotransmitter-specific proteins to assemble, store, mobilize, and break down one or more of potentially hundreds of chemically diverse transmitter molecules. Individual molecules generate signals over different timescales and spatial domains by interacting with multiple receptor types. Moreover, rather than functioning through the use of a single neurotransmitter, most, if not all, synapses likely operate through the co-release of multiple neurotransmitters. Even the idea that signals are transmitted in a ‘forward direction’ is an oversimplification—certain neurotransmitters signal in the reverse direction. These issues, and more, are reviewed here.
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Alatzoglou, Kyriaki S., and Mehul T. Dattani. "Development of the pituitary and genetic forms of hypopituitarism." In Oxford Textbook of Endocrinology and Diabetes, 99–112. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199235292.003.2040.
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Pituitary development occurs in distinct and sequential developmental steps, leading to the formation of a complex organ containing five different cell types secreting six different hormones. During this process the sequential temporal and spatial expression of a cascade of signalling molecules and transcription factors play a crucial role in organ commitment, cell proliferation, patterning, and terminal differentiation. Complex regulatory networks govern the process during which distinct cell types emerge from a common primordium. The mechanisms are not fully elucidated but it seems that opposing signalling gradients induce expression of interacting transcriptional regulators (activators or repressors) in overlapping patterns that act synergistically. Spontaneous or artificially induced mutations in the mouse and identification of mutations associated with human pituitary disease have contributed to defining the genetic cascades responsible for pituitary development.
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Warrant, Eric, and U. Homberg. "Research Spotlight—Insect Polarization Vision: Peripheral And Central Mechanisms." In Structure and Evolution of Invertebrate Nervous Systems, 646–51. Oxford University PressOxford, 2015. http://dx.doi.org/10.1093/acprof:oso/9780199682201.003.0049.
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Abstract The ability to detect linearly polarized light is used by insects for spatial orientation, object identification and, in a few cases, sexual signalling. The use of polarization vision for sky compass orientation has received particular attention. Scattering of sunlight by air molecules generates a pattern of skylight polarization, which insects can use, just like the sun itself, as a visual celestial compass. Polarized skylight is detected by specialized ommatidia in the so-called dorsal rim area of the eye. In this eye region, ommatidial photoreceptors have highly aligned rhodopsin-bearing microvilli, resulting in high polarization sensitivity. Photoreceptors are homochromatic and occur in each ommatidium as sets of receptors with orthogonal microvillar orientations. Antagonistic input from these photoreceptors likely results in polarization-opponency in neurons of the polarization vision pathway in the brain. Studies in locusts, monarch butterflies, and a few other species have shown that convergence of signals from both eyes occurs in the central complex, a group of midline-spanning neuropils in the brain. Here, bilateral integration results in a compass-like topographic representation of zenithal E-vectors, which may be used as a frame of reference for spatial memory, path integration, and other spatial tasks. Integration of other celestial cues, such as the sky chromatic contrast, occurs at central stages of the polarization vision system, presumably to increase the robustness of the sky compass signal.
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Freeden, Michael. "The Temporalities of Silence: Theology, History, Anthropology." In Concealed Silences and Inaudible Voices in Political Thinking, 153–70. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780198833512.003.0011.
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Abstract This chapter explores modes of processing silences evident in the imaginative and cultural traditions spread over the field of human inventiveness. Theological and philosophical perspectives contemplate silence as preceding and following creation, signalling two eternities encircling being, logocentricity, and discourse. As the latter are forms of temporal order and shaping, they signify a quintessential political process. Silence plays a central role in religious rituals: Communion, deference, or participation demarcate social roles, assuring stability and room for a partial retreat from everyday life, combining temporal and spatial categories. Historical narratives stitch together the hollows in their subject-matter through fictions, myths, and imaginaries. Any account of history or of biography involves silencing—through prioritizing and ranking, through forgetfulness or chance misplacement, through embarrassment or pride, through marginalizing certain groups, and through stifling alternative narratives, whether intentional or unnoticed. Residual evidence can assist scholarship in identifying those silences. Anthropology attempts to uncover the submergence of indigenous peoples by more recent cultures, and investigates the individual silences of those who cannot make the transition. Assumptions of linear development have silenced and contorted the complexities of lived reality, neutralizing underlying tensions. The silences of the past can be interrogated or refuted. The silences of the future are beyond reach and fragile. But both categories offer an ample platform on which to conduct struggles over policy.
Conference papers on the topic "Spatial organiser of signalling"
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Masouros, Christos, and Lajos Hanzo. "Bandwidth efficient spatial modulation by signalling in the power domain." In ICC 2016 - 2016 IEEE International Conference on Communications. IEEE, 2016. http://dx.doi.org/10.1109/icc.2016.7511398.
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Mossaad, Mohammed S. A., and Steve Hranilovic. "Practical OFDM signalling for visible light communications using spatial summation." In 2014 27th Biennial Symposium on Communications (QBSC). IEEE, 2014. http://dx.doi.org/10.1109/qbsc.2014.6841173.
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Baddeley, David, Isuru Jayasinghe, Cherrie Kong, David Crossman, Juliette Cheyne, Johanna Montgomery, Mark Cannell, and Christian Soeller. "4D spatial-spectral super-resolution imaging of nanoscopic membrane signalling domains." In 2011 International Quantum Electronics Conference (IQEC) and Conference on Lasers and Electro-Optics (CLEO) Pacific Rim. IEEE, 2011. http://dx.doi.org/10.1109/iqec-cleo.2011.6194007.
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Dalchau, N., P. K. Grant, J. R. Brown, A. Phillips, and J. Haseloff. "Programming spatial patterns in bacterial colonies using engineered orthogonal signalling channels." In IET/SynbiCITE Engineering Biology Conference. Institution of Engineering and Technology, 2016. http://dx.doi.org/10.1049/cp.2016.1237.
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Qian, Chen, Weifeng Li, Dongyuan Yang, Bin Ran, and Feng Li. "Measuring Spatial Distribution of Tourist Flows Based on Cellular Signalling Data: A Case Study of Shangha." In 2019 IEEE Intelligent Transportation Systems Conference - ITSC. IEEE, 2019. http://dx.doi.org/10.1109/itsc.2019.8917262.
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Barić, Danijela, Silvestar Grabušić, and Dražen Kaužljar. "Barriers and half-barriers - violation at level crossings: A case study of drivers behaviour in Croatia." In 7th International Conference on Road and Rail Infrastructure. University of Zagreb Faculty of Civil Engineering, 2022. http://dx.doi.org/10.5592/co/cetra.2022.1455.
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This study investigates accidents at active level crossings (LCs) in Croatia (A.1.3., by ERA classification) equipped with barriers or half-barriers and warning automatic devices (light and sound signalling). Statistical data were collected to identify the number of yearly broken barriers and half-barriers, causes, consequences, time, location and spatial distribution of accidents. Only collisions with barriers and half-barriers were analysed. Although active LC protection systems effectively prevent accidents due to road user errors, there are many broken barriers or half barriers at the LCs (378 in 2020, 435 in 2019), which indicate risky driving behaviour of LC users. The results of the analysis show a declining trend. Still, as the high number of barriers or half-barriers at the LCs were in most cases broken just before the train was approaching, for which they were lowered, this could have led to severe accidents. Based on this, we can assume that the most significant focus of accident prevention and improving safety at LCs in the future need to be on human behaviour.
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Neves a b, João, and Fernando Moreira da Silva b. "Wayfinding Design: An Ergonomic Approach to Signage Systems." In Applied Human Factors and Ergonomics Conference. AHFE International, 2022. http://dx.doi.org/10.54941/ahfe100771.
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Signage systems are closely linked to the security of persons and goods, as well as pressing issues such as ergonomics, accessibility, orientation, and mobility, among others. Signaling traffic, tourism, emergency signaling, railway signaling, air, maritime, etc., well reflect the role of signage/signalization in contributing to the safety and mobility of societies and the social role of design as a methodology or discipline that conceives orientation signs in space – The Signage systems. The potential benefits of information design (more properly signage systems) for social development are also looking for new approaches and methodologies, for research in and by design in an attempt to maximize new solutions that improve the lives of societies. The found solutions at the level of signage systems do not always consider the real needs of multiple users, i.e., at the level of design of these systems lack truly design projects centred on the users and that incorporate real solutions at technical, aesthetic, ergonomic and also inclusive levels. The development of signalling systems, which are considered as spatial information systems, involves the vital function of transmitting information in order to guide and direct certain individuals or groups / classes of individuals. It is a communication process that uses artifacts designed for the transmission of information and guidance clear and unambiguous for Citizens: The wayfinding. Considering wayfinding as the organization and communication of our dynamic relationship with space and environment, we are in the field of an important area for the design, to architecture and ergonomics, which is not only limited to the design of systems, but all that pertains to human interaction with spaces (Arthur; Passini, 1992). Thus, wayfinding design seeks to develop activity in the design of signage systems and of spatial information, which aim to guide and assist the task of accessibility to a particular space or territory. It is understood to be fundamentally a user-centred approach, which favors the ergonomic issues, anthropometric and inclusiveness, making signage systems truly universal or rather, accessible to a majority.
Reports on the topic "Spatial organiser of signalling"
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Yuval, Boaz, and Todd E. Shelly. Lek Behavior of Mediterranean Fruit Flies: An Experimental Analysis. United States Department of Agriculture, July 2000. http://dx.doi.org/10.32747/2000.7575272.bard.
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The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), is a ubiquitous pest of fruit trees, causing significant economic damage both in the U.S. and in Israel. Control efforts in the future will rely heavily on the sterile insect technique (SIT). Success of such operations hinges on the competitive ability of released males. The mating system of the medfly is based on leks. These are aggregations of sexually signaling males that attract females (who then select and copulate a courting male). A major component of male competitiveness is their ability to join existing leks or establish leks that are attractive to wild females. Accordingly, we identified leks and the behaviors associated with them as critical for the success of SIT operations. The objectives of this proposal were to determine 1. what makes a good lek site, 2. what are the energetic costs of lekking, 3. how females choose leks, and finally 4. whether the copulatory success of sterile males may be manipulated by particular pre-release diets and judicious spatial dispersal. We established that males choose lek sites according to their spatial location and penological status, that they avoid predators, and within the lek tree choose the perch that affords a compromise between optimal signalling, micro-climatic conditions and predation risk (Kaspi & Yuval 1999 a&b; Field et al 2000; Kaspi & Yuval submitted). We were able to show that leks are exclusive, and that only males with adequate protein and carbohydrate reserves can participate (Yuval et al 1998; Kaspi et al 2000; Shelly et al 2000). We determined that females prefer leks formed by protein fed, sexually experienced males (Shelly 2000). Finally, we demonstrated that adding protein to the diet of sterile males significantly enhances their probability of participating in leks and copulating wild females (Kaspi & Yuval 2000).
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Friedman, Haya, Julia Vrebalov, James Giovannoni, and 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, January 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.