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Stochastic gene

Huei-Mien Ke, Dang Liu, Yoshitoshi Ogura, Tetsuya Hayashi, Henryk Urbanczyk, Isheng J Tsai
The mechanism of bacterial speciation remains a topic of tremendous interest. To understand the ecological and evolutionary mechanisms of speciation in Vibrio bacteria, we analyzed the genomic dissimilarities between three closely related species in the so-called Harveyi clade of the genus Vibrio : V. campbellii , V. jasicida and V. hyugaensis The analysis focused on strains isolated from diverse geographic locations, over a long period of time. Results of phylogenetic analyses and calculations of average nucleotide identities (ANI) supported classification of V...
March 19, 2018: Journal of Bacteriology
Simona Patange, Michelle Girvan, Daniel R Larson
Gene expression varies across cells in a population or a tissue. This heterogeneity has come into sharp focus in recent years through developments in new imaging and sequencing technologies. However, our ability to measure variation has outpaced our ability to interpret it. Much of the variability may arise from random effects occurring in the processes of gene expression (transcription, RNA processing and decay, translation). The molecular basis of these effects is largely unknown. Likewise, a functional role of this variability in growth, differentiation and disease has only been elucidated in a few cases...
April 2018: Current Opinion in Systems Biology
Davar Abedini, Sajad Rashidi Monfared
A primary mechanism for controlling the development of multicellular organisms is transcriptional regulation, which carried out by transcription factors (TFs) that recognize and bind to their binding sites on promoter region. The distance from translation start site, order, orientation, and spacing between cis elements are key factors in the concentration of active nuclear TFs and transcriptional regulation of target genes. In this study, overrepresented motifs in cold and pathogenesis responsive genes were scanned via Gibbs sampling method, this method is based on detection of overrepresented motifs by means of a stochastic optimization strategy that searches for all possible sets of short DNA segments...
March 17, 2018: Molecular Biology Reports
Ovidiu Lipan, Cameron Ferwerda
The deterministic Hill function depends only on the average values of molecule numbers. To account for the fluctuations in the molecule numbers, the argument of the Hill function needs to contain the means, the standard deviations, and the correlations. Here we present a method that allows for stochastic Hill functions to be constructed from the dynamical evolution of stochastic biocircuits with specific topologies. These stochastic Hill functions are presented in a closed analytical form so that they can be easily incorporated in models for large genetic regulatory networks...
February 2018: Physical Review. E
Sandeep Choubey
Regulation of transcription is a vital process in cells, but mechanistic details of this regulation still remain elusive. The dominant approach to unravel the dynamics of transcriptional regulation is to first develop mathematical models of transcription and then experimentally test the predictions these models make for the distribution of mRNA and protein molecules at the individual cell level. However, these measurements are affected by a multitude of downstream processes which make it difficult to interpret the measurements...
February 2018: Physical Review. E
Ole Petter Rekvig
Systemic lupus erythematosus (SLE) is an inadequately defined syndrome. Etiology and pathogenesis remain largely unknown. SLE is on the other hand a seminal syndrome that has challenged immunologists, biologists, genetics, and clinicians to solve its nature. The syndrome is characterized by multiple, etiologically unlinked manifestations. Unexpectedly, they seem to occur in different stochastically linked clusters, although single gene defects may promote a smaller spectrum of symptoms/criteria typical for SLE...
2018: Frontiers in Immunology
Sigrun Schmähling, Arno Meiler, Yoonjung Lee, Arif Mohammed, Katja Finkl, Katharina Tauscher, Lars Israel, Marc Borath, Julia Philippou-Massier, Helmut Blum, Bianca Habermann, Axel Imhof, Ji-Joon Song, Jürg Müller
The Drosophila Ash1 protein is a trithorax-group (trxG) regulator that antagonizes Polycomb repression at HOX genes. Ash1 di-methylates lysine 36 in histone H3 (H3K36me2) but how this activity is controlled and at which genes it functions is not well understood. We show that Ash1 protein purified from Drosophila exists in a complex with MRG15 and Caf1 that we named AMC. In Drosophila and human AMC, MRG15 binds a conserved FxLP motif near the Ash1 SET domain and stimulates H3K36 di-methylation on nucleosomes...
March 14, 2018: Development
Jennifer M SanMiguel, Lara K Abramowitz, Marisa S Bartolomei
Imprinted genes are expressed from one parental allele and regulated by differential DNA methylation at imprinting control regions (ICR). ICRs are reprogrammed in the germline through erasure and reestablishment of DNA methylation. Although much is known about DNA methylation establishment, DNA demethylation is less well understood. Recently, the Ten-Eleven Translocation proteins (TET1-3) have been shown to initiate DNA demethylation, with Tet1 -/- mice exhibiting aberrant levels of imprinted gene expression and ICR methylation...
March 12, 2018: Development
Hao Ge, Pingping Wu, Hong Qian, Sunney Xiaoliang Xie
Within an isogenic population, even in the same extracellular environment, individual cells can exhibit various phenotypic states. The exact role of stochastic gene-state switching regulating the transition among these phenotypic states in a single cell is not fully understood, especially in the presence of positive feedback. Recent high-precision single-cell measurements showed that, at least in bacteria, switching in gene states is slow relative to the typical rates of active transcription and translation...
March 12, 2018: PLoS Computational Biology
Jakob B Butler, Jules S Freeman, Brad M Potts, René E Vaillancourt, Dario Grattapaglia, Orzenil B Silva-Junior, Blake A Simmons, Adam L Healey, Jeremy Schmutz, Kerrie W Barry, David J Lee, Robert J Henry, Graham J King, Abdul Baten, Mervyn Shepherd
Terpenes are economically and ecologically important phytochemicals. Their synthesis is controlled by the terpene synthase (TPS) gene family, which is highly diversified throughout the plant kingdom. The plant family Myrtaceae are characterised by especially high terpene concentrations, and considerable variation in terpene profiles. Many Myrtaceae are grown commercially for terpene products including the eucalypts Corymbia and Eucalyptus. Eucalyptus grandis has the largest TPS gene family of plants currently sequenced, which is largely conserved in the closely related E...
March 10, 2018: Heredity
Faizan Ehsan Elahi, Ammar Hasan
Gene regulatory networks (GRNs) are quite large and complex. To better understand and analyse GRNs, mathematical models are being employed. Different types of models, such as logical, continuous and stochastic models, can be used to describe GRNs. In this paper, we present a new approach to identify continuous models, because they are more suitable for large number of genes and quantitative analysis. One of the most promising techniques for identifying continuous models of GRNs is based on Hill functions and the generalized profiling method (GPM)...
February 2018: Royal Society Open Science
Garrett Jenkinson, Jordi Abante, Andrew P Feinberg, John Goutsias
BACKGROUND: DNA methylation is a stable form of epigenetic memory used by cells to control gene expression. Whole genome bisulfite sequencing (WGBS) has emerged as a gold-standard experimental technique for studying DNA methylation by producing high resolution genome-wide methylation profiles. Statistical modeling and analysis is employed to computationally extract and quantify information from these profiles in an effort to identify regions of the genome that demonstrate crucial or aberrant epigenetic behavior...
March 7, 2018: BMC Bioinformatics
Patrick Kennedy, Andrew D Higginson, Andrew N Radford, Seirian Sumner
The evolution of altruism-costly self-sacrifice in the service of others-has puzzled biologists since The Origin of Species. For half a century, attempts to understand altruism have developed around the concept that altruists may help relatives to have extra offspring in order to spread shared genes. This theory-known as inclusive fitness-is founded on a simple inequality termed Hamilton's rule. However, explanations of altruism have typically not considered the stochasticity of natural environments, which will not necessarily favour genotypes that produce the greatest average reproductive success...
March 7, 2018: Nature
Xiaojian Shao, Ming-An Sun
The level of gene expression is known to vary from cell to cell and even in the same cell over time. This variability provides cells with the ability to mitigate environmental stresses and genetic perturbations, and facilitates gene expression evolution. Recently, many valuable gene expression noise data measured at the single-cell level and gene expression variation measured for cell populations have become available. In this chapter, we show how to perform integrative analysis using these data. Specifically, we introduce how to apply a machine learning technique (support vector regression) to explore the relationship between gene expression variations and stochastic noise...
2018: Methods in Molecular Biology
Jeffrey N Carey, Erin L Mettert, Manuela Roggiani, Kevin S Myers, Patricia J Kiley, Mark Goulian
Microbial populations can maximize fitness in dynamic environments through bet hedging, a process wherein a subpopulation assumes a phenotype not optimally adapted to the present environment but well adapted to an environment likely to be encountered. Here, we show that oxygen induces fluctuating expression of the trimethylamine oxide (TMAO) respiratory system of Escherichia coli, diversifying the cell population and enabling a bet-hedging strategy that permits growth following oxygen loss. This regulation by oxygen affects the variance in gene expression but leaves the mean unchanged...
February 26, 2018: Cell
Simon Maccracken Stump, Evan Curtis Johnson, Zepeng Sun, Christopher A Klausmeier
The ubiquity of cooperative cross-feeding (a resource-exchange mutualism) raises two related questions: Why is cross-feeding favored over self-sufficiency, and how are cross-feeders protected from non-producing cheaters? The Black Queen Hypothesis suggests that if leaky resources are costly, then there should be selection for either gene loss or self-sufficiency, but selection against mutualistic inter-dependency. Localized interactions have been shown to protect mutualists against cheaters, though their effects in the presence of self-sufficient organisms are not well understood...
February 27, 2018: Journal of Theoretical Biology
Trung Nghia Vu, Quin F Wills, Krishna R Kalari, Nifang Niu, Liewei Wang, Yudi Pawitan, Mattias Rantalainen
Motivation: RNA sequencing of single cells enables characterization of transcriptional heterogeneity in seemingly homogeneous cell populations. Single-cell sequencing has been applied in a wide range of researches fields. However, few studies have focus on characterization of isoform-level expression patterns at the single-cell level. In this study we propose and apply a novel method, ISOform-Patterns (ISOP), based on mixture modeling, to characterize the expression patterns of isoform pairs from the same gene in single-cell isoform-level expression data...
February 27, 2018: Bioinformatics
Pablo I Nikel, Víctor de Lorenzo
The soil bacterium Pseudomonas putida is rapidly becoming a platform of choice for applications that require a microbial host highly resistant to different types of stresses and elevated rates of reducing power regeneration. P. putida is capable of growing in a wide variety of carbon sources that range from simple sugars to complex substrates such as aromatic compounds. Interestingly, the growth of the reference strain KT2440 on glycerol as the sole carbon source is characterized by a prolonged lag phase, not observed with other carbon substrates...
2018: Methods in Molecular Biology
Christoph Fritzsch, Stephan Baumgärtner, Monika Kuban, Daria Steinshorn, George Reid, Stefan Legewie
Cellular decision-making and environmental adaptation are dependent upon a heterogeneous response of gene expression to external cues. Heterogeneity arises in transcription from random switching between transcriptionally active and inactive states, resulting in bursts of RNA synthesis. Furthermore, the cellular state influences the competency of transcription, thereby globally affecting gene expression in a cell-specific manner. We determined how external stimuli interplay with cellular state to modulate the kinetics of bursting...
February 23, 2018: Molecular Systems Biology
Chandrani Das, Chaitanya Mokashi, Sharmila S Mande, Supreet Saini
The food-borne pathogen Salmonella typhimurium is a common cause of infections and diseases in a wide range of hosts. One of the major virulence factors associated to the infection process is flagella, which helps the bacterium swim to its preferred site of infection inside the host, the M-cells (Microfold cells) lining the lumen of the small intestine. The expression of flagellar genes is controlled by an intricate regulatory network. In this work, we investigate two aspects of flagella regulation and assembly: (a) distribution of the number of flagella in an isogenic population of bacteria and (b) dynamics of gene expression post cell division...
2018: Frontiers in Cellular and Infection Microbiology
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