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Bistable networks

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https://www.readbyqxmd.com/read/28525544/bistability-causality-and-complexity-in-cortical-networks-an-in-vitro-perturbational-study
#1
Mattia D'Andola, Beatriz Rebollo, Adenauer G Casali, Julia F Weinert, Andrea Pigorini, Rosa Villa, Marcello Massimini, Maria V Sanchez-Vives
Measuring the spatiotemporal complexity of cortical responses to direct perturbations provides a reliable index of the brain's capacity for consciousness in humans under both physiological and pathological conditions. Upon loss of consciousness, the complex pattern of causal interactions observed during wakefulness collapses into a stereotypical slow wave, suggesting that cortical bistability may play a role. Bistability is mainly expressed in the form of slow oscillations, a default pattern of activity that emerges from cortical networks in conditions of functional or anatomical disconnection...
May 19, 2017: Cerebral Cortex
https://www.readbyqxmd.com/read/28505836/stationary-patterns-in-star-networks-of-bistable-units-theory-and-application-to-chemical-reactions
#2
Nikos E Kouvaris, Michael Sebek, Albert Iribarne, Albert Díaz-Guilera, István Z Kiss
We present theoretical and experimental studies on pattern formation with bistable dynamical units coupled in a star network configuration. By applying a localized perturbation to the central or the peripheral elements, we demonstrate the subsequent spreading, pinning, or retraction of the activations; such analysis enables the characterization of the formation of stationary patterns of localized activity. The results are interpreted with a theoretical analysis of a simplified bistable reaction-diffusion model...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28505785/noise-induced-polarization-switching-in-complex-networks
#3
Jan O Haerter, Albert Díaz-Guilera, M Ángeles Serrano
The combination of bistability and noise is ubiquitous in complex systems, from biology to social interactions, and has important implications for their functioning and resilience. Here we use a simple three-state dynamical process, in which nodes go from one pole to another through an intermediate state, to show that noise can induce polarization switching in bistable systems if dynamical correlations are significant. In large, fully connected networks, where dynamical correlations can be neglected, increasing noise yields a collapse of bistability to an unpolarized configuration where the three possible states of the nodes are equally likely...
April 2017: Physical Review. E
https://www.readbyqxmd.com/read/28484034/modeling-the-response-of-a-tumor-suppressive-network-to-mitogenic-and-oncogenic-signals
#4
Xinyu Tian, Bo Huang, Xiao-Peng Zhang, Mingyang Lu, Feng Liu, José N Onuchic, Wei Wang
Intrinsic tumor-suppressive mechanisms protect normal cells against aberrant proliferation. Although cellular signaling pathways engaged in tumor repression have been largely identified, how they are orchestrated to fulfill their function still remains elusive. Here, we built a tumor-suppressive network model composed of three modules responsible for the regulation of cell proliferation, activation of p53, and induction of apoptosis. Numerical simulations show a rich repertoire of network dynamics when normal cells are subject to serum stimulation and adenovirus E1A overexpression...
May 8, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28415301/nonlinear-signaling-on-biological-networks-the-role-of-stochasticity-and-spectral-clustering
#5
Gonzalo Hernandez-Hernandez, Jesse Myers, Enrique Alvarez-Lacalle, Yohannes Shiferaw
Signal transduction within biological cells is governed by networks of interacting proteins. Communication between these proteins is mediated by signaling molecules which bind to receptors and induce stochastic transitions between different conformational states. Signaling is typically a cooperative process which requires the occurrence of multiple binding events so that reaction rates have a nonlinear dependence on the amount of signaling molecule. It is this nonlinearity that endows biological signaling networks with robust switchlike properties which are critical to their biological function...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28397813/nonlinear-dynamics-and-chaos-in-an-optomechanical-beam
#6
Daniel Navarro-Urrios, Néstor E Capuj, Martín F Colombano, P David García, Marianna Sledzinska, Francesc Alzina, Amadeu Griol, Alejandro Martínez, Clivia M Sotomayor-Torres
Optical nonlinearities, such as thermo-optic mechanisms and free-carrier dispersion, are often considered unwelcome effects in silicon-based resonators and, more specifically, optomechanical cavities, since they affect, for instance, the relative detuning between an optical resonance and the excitation laser. Here, we exploit these nonlinearities and their intercoupling with the mechanical degrees of freedom of a silicon optomechanical nanobeam to unveil a rich set of fundamentally different complex dynamics...
April 11, 2017: Nature Communications
https://www.readbyqxmd.com/read/28369623/the-hidden-life-of-integrative-and-conjugative-elements
#7
François Delavat, Ryo Miyazaki, Nicolas Carraro, Nicolas Pradervand, Jan Roelof van der Meer
Integrative and conjugative elements (ICEs) are widespread mobile DNA that transmit both vertically, in a host-integrated state, and horizontally, through excision and transfer to new recipients. Different families of ICEs have been discovered with more or less restricted host ranges, which operate by similar mechanisms but differ in regulatory networks, evolutionary origin and the types of variable genes they contribute to the host. Based on reviewing recent experimental data, we propose a general model of ICE life style that explains the transition between vertical and horizontal transmission as a result of a bistable decision in the ICE-host partnership...
March 25, 2017: FEMS Microbiology Reviews
https://www.readbyqxmd.com/read/28369103/chemical-reaction-network-theory-elucidates-sources-of-multistability-in-interferon-signaling
#8
Irene Otero-Muras, Pencho Yordanov, Joerg Stelling
Bistability has important implications in signaling pathways, since it indicates a potential cell decision between alternative outcomes. We present two approaches developed in the framework of the Chemical Reaction Network Theory for easy and efficient search of multiple steady state behavior in signaling networks (both with and without mass conservation), and apply them to search for sources of bistability at different levels of the interferon signaling pathway. Different type I interferon subtypes and/or doses are known to elicit differential bioactivities (ranging from antiviral, antiproliferative to immunomodulatory activities)...
April 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28280580/organization-of-biogeochemical-nitrogen-pathways-with-switch-like-adjustment-in-fluctuating-soil-redox-conditions
#9
Sanjay Lamba, Soumen Bera, Mubasher Rashid, Alexander B Medvinsky, Gui-Quan Sun, Claudia Acquisti, Amit Chakraborty, Bai-Lian Li
Nitrogen is cycled throughout ecosystems by a suite of biogeochemical processes. The high complexity of the nitrogen cycle resides in an intricate interplay between reversible biochemical pathways alternatively and specifically activated in response to diverse environmental cues. Despite aggressive research, how the fundamental nitrogen biochemical processes are assembled and maintained in fluctuating soil redox conditions remains elusive. Here, we address this question using a kinetic modelling approach coupled with dynamical systems theory and microbial genomics...
January 2017: Royal Society Open Science
https://www.readbyqxmd.com/read/28246663/steady-state-statistical-correlations-predict-bistability-in-reaction-motifs
#10
Suchana Chakravarty, Debashis Barik
Various cellular decision making processes are regulated by bistable switches that take graded input signals and convert them to binary all-or-none responses. Traditionally, a bistable switch generated by a positive feedback loop is characterized either by a hysteretic signal response curve with two distinct signaling thresholds or by characterizing the bimodality of the response distribution in the bistable region. To identify the intrinsic bistability of a feedback regulated network, here we propose that bistability can be determined by correlating higher order moments and cumulants (≥2) of the joint steady state distributions of two components connected in a positive feedback loop...
March 1, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28245235/the-role-of-the-hes1-crosstalk-hub-in-notch-wnt-interactions-of-the-intestinal-crypt
#11
Sophie K Kay, Heather A Harrington, Sarah Shepherd, Keith Brennan, Trevor Dale, James M Osborne, David J Gavaghan, Helen M Byrne
The Notch pathway plays a vital role in determining whether cells in the intestinal epithelium adopt a secretory or an absorptive phenotype. Cell fate specification is coordinated via Notch's interaction with the canonical Wnt pathway. Here, we propose a new mathematical model of the Notch and Wnt pathways, in which the Hes1 promoter acts as a hub for pathway crosstalk. Computational simulations of the model can assist in understanding how healthy intestinal tissue is maintained, and predict the likely consequences of biochemical knockouts upon cell fate selection processes...
February 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28219776/deactivation-in-the-posterior-mid-cingulate-cortex-reflects-perceptual-transitions-during-binocular-rivalry-evidence-from-simultaneous-eeg-fmri
#12
Abhrajeet V Roy, Keith W Jamison, Sheng He, Stephen A Engel, Bin He
Binocular rivalry is a phenomenon in which perception spontaneously shifts between two different images that are dichoptically presented to the viewer. By elucidating the cortical networks responsible for these stochastic fluctuations in perception, we can potentially learn much about the neural correlates of visual awareness. We obtained concurrent EEG-fMRI data for a group of 20 healthy human subjects during the continuous presentation of dichoptic visual stimuli. The two eyes' images were tagged with different temporal frequencies so that eye specific steady-state visual evoked potential (SSVEP) signals could be extracted from the EEG data for direct comparison with changes in fMRI BOLD activity associated with binocular rivalry...
February 20, 2017: NeuroImage
https://www.readbyqxmd.com/read/28122551/sampling-based-bayesian-approaches-reveal-the-importance-of-quasi-bistable-behavior-in-cellular-decision-processes-on-the-example-of-the-mapk-signaling-pathway-in-pc-12-cell-lines
#13
Antje Jensch, Caterina Thomaseth, Nicole E Radde
BACKGROUND: Positive and negative feedback loops are ubiquitous motifs in biochemical signaling pathways. The mitogen-activated protein kinase (MAPK) pathway module is part of many distinct signaling networks and comprises several of these motifs, whose functioning depends on the cell line at hand and on the particular context. The maintainance of specificity of the response of the MAPK module to distinct stimuli has become a key paradigm especially in PC-12 cells, where the same module leads to different cell fates, depending on the stimulating growth factor...
January 25, 2017: BMC Systems Biology
https://www.readbyqxmd.com/read/28112462/bistability-and-bifurcation-in-minimal-self-replication-and-nonenzymatic-catalytic-networks
#14
Nathaniel Wagner, Rakesh Mukherjee, Indrajit Maity, Enrique Peacock-Lopez, Gonen Ashkenasy
Bistability and bifurcation, found in a wide range of biochemical networks, are central to the proper function of living systems. We investigate herein recent model systems that show bistable behavior based on nonenzymatic self-replication reactions. Such models were used before to investigate catalytic growth, chemical logic operations, and additional processes of self-organization leading to complexification. By solving for their steady-state solutions by using various analytical and numerical methods, we analyze how and when these systems yield bistability and bifurcation and discover specific cases and conditions producing bistability...
January 23, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/27984903/steady-state-equivalence-among-autocatalytic-peroxidase-oxidase-reactions
#15
José Méndez-González, Ricardo Femat
Peroxidase-oxidase is an enzymatic reaction that can exhibit dynamical scenarios such as bistability, sustained oscillations, and Shilnikov chaos. In this work, we apply the chemical reaction network theory approach to find kinetic constants such that the associated mass action kinetics ordinary differential equations induced by three four dimensional structurally different enzymatic reaction systems can support the same steady states for several chemical species despite differences in their chemical nature...
December 14, 2016: Journal of Chemical Physics
https://www.readbyqxmd.com/read/27967004/robustness-of-persistent-spiking-to-partial-synchronization-in-a-minimal-model-of-synaptically-driven-self-sustained-activity
#16
Nikita Novikov, Boris Gutkin
We study the behavior of a minimal model of synaptically sustained persistent activity that consists of two quadratic integrate-and-fire neurons mutually coupled via excitatory synapses. Importantly, each of the neurons is excitable, as opposed to an oscillator; hence when uncoupled it sits at a subthreshold rest state. When the constituent neurons are mutually coupled via sufficiently strong fast excitatory synapses, the system demonstrates bistability between a fixed point (quiescent background state) and a limit cycle (memory state with synaptically driven spiking activity)...
November 2016: Physical Review. E
https://www.readbyqxmd.com/read/27931974/mathematical-modeling-of-atopic-dermatitis-reveals-double-switch-mechanisms-underlying-4-common-disease-phenotypes
#17
Elisa Domínguez-Hüttinger, Panayiotis Christodoulides, Kosuke Miyauchi, Alan D Irvine, Mariko Okada-Hatakeyama, Masato Kubo, Reiko J Tanaka
BACKGROUND: The skin barrier acts as the first line of defense against constant exposure to biological, microbial, physical, and chemical environmental stressors. Dynamic interplay between defects in the skin barrier, dysfunctional immune responses, and environmental stressors are major factors in the development of atopic dermatitis (AD). A systems biology modeling approach can yield significant insights into these complex and dynamic processes through integration of prior biological data...
December 5, 2016: Journal of Allergy and Clinical Immunology
https://www.readbyqxmd.com/read/27927198/a-computational-method-for-the-investigation-of-multistable-systems-and-its-application-to-genetic-switches
#18
Miriam Leon, Mae L Woods, Alex J H Fedorec, Chris P Barnes
BACKGROUND: Genetic switches exhibit multistability, form the basis of epigenetic memory, and are found in natural decision making systems, such as cell fate determination in developmental pathways. Synthetic genetic switches can be used for recording the presence of different environmental signals, for changing phenotype using synthetic inputs and as building blocks for higher-level sequential logic circuits. Understanding how multistable switches can be constructed and how they function within larger biological systems is therefore key to synthetic biology...
December 7, 2016: BMC Systems Biology
https://www.readbyqxmd.com/read/27911933/driving-cells-to-the-desired-state-in-a-bimodal-distribution-through-manipulation-of-internal-noise-with-biologically-practicable-approaches
#19
Che-Chi Shu, Chen-Chao Yeh, Wun-Sin Jhang, Shih-Chiang Lo
The stochastic nature of gene regulatory networks described by Chemical Master Equation (CME) leads to the distribution of proteins. A deterministic bistability is usually reflected as a bimodal distribution in stochastic simulations. Within a certain range of the parameter space, a bistable system exhibits two stable steady states, one at the low end and the other at the high end. Consequently, it appears to have a bimodal distribution with one sub-population (mode) around the low end and the other around the high end...
2016: PloS One
https://www.readbyqxmd.com/read/27902489/effects-of-cell-cycle-noise-on-excitable-gene-circuits
#20
Alan Veliz-Cuba, Chinmaya Gupta, Matthew R Bennett, Krešimir Josić, William Ott
We assess the impact of cell cycle noise on gene circuit dynamics. For bistable genetic switches and excitable circuits, we find that transitions between metastable states most likely occur just after cell division and that this concentration effect intensifies in the presence of transcriptional delay. We explain this concentration effect with a three-states stochastic model. For genetic oscillators, we quantify the temporal correlations between daughter cells induced by cell division. Temporal correlations must be captured properly in order to accurately quantify noise sources within gene networks...
November 30, 2016: Physical Biology
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