Faculty Opinions recommendation of Mapping the core of the Arabidopsis circadian clock defines the network structure of the oscillator.

2013 ◽  
Author(s):  
C Robertson McClung
Keyword(s):  
Circadian Clock ◽  
Network Structure ◽  
The Core

scholarly journals Mapping the Core of the Arabidopsis Circadian Clock Defines the Network Structure of the Oscillator

Science ◽  
2012 ◽  
Vol 336 (6077) ◽  
pp. 75-79 ◽  
Author(s):  
W. Huang ◽  
P. Pérez-García ◽  
A. Pokhilko ◽  
A. J. Millar ◽  
I. Antoshechkin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Interference ◽  
Circadian Clock ◽  
Network Structure ◽  
The Core

In many organisms, the circadian clock is composed of functionally coupled morning and evening oscillators. In Arabidopsis, oscillator coupling relies on a core loop in which the evening oscillator component TIMING OF CAB EXPRESSION 1 (TOC1) was proposed to activate a subset of morning-expressed oscillator genes. Here, we show that TOC1 does not function as an activator but rather as a general repressor of oscillator gene expression. Repression occurs through TOC1 rhythmic association to the promoters of the oscillator genes. Hormone-dependent induction of TOC1 and analysis of RNA interference plants show that TOC1 prevents the activation of morning-expressed genes at night. Our study overturns the prevailing model of the Arabidopsis circadian clock, showing that the morning and evening oscillator loops are connected through the repressing activity of TOC1.

Weak-Tie Confidants

2017 ◽  
Author(s):  
Mario Luis Small
Keyword(s):  
Social Interaction ◽  
Graduate Students ◽  
Network Structure ◽  
Relative Importance ◽  
The Core ◽  
Structure Versus

This chapter examines the “core discussion networks” of graduate students in three departments and shows that, contrary to traditional expectations, many of the ties appear to be weak rather than strong. It considers how the students relate to those they have considered their confidants after six months, and more specifically whether they would as a whole report the same confidants. Three perspectives on the relative importance of network structure versus social interaction are discussed based on the students’ different experiences: the students will keep most confidants, they will drop many of their confidants, or they will drop many confidants but quickly replace them. In general, the students replaced their confidants often.

scholarly journals Cooperative optimality principals in differential games on networks

2020 ◽  
Vol 12 (4) ◽  
pp. 93-111
Author(s):  
Анна Тур ◽  
Anna Tur ◽  
Леон Аганесович Петросян ◽  
Leon Petrosyan
Keyword(s):  
Characteristic Function ◽  
Differential Games ◽  
Network Structure ◽  
Shapley Value ◽  
The Core ◽  
Investment Game ◽  
The Shapley Value ◽  
Research Investment ◽  
Optimality Principles

The paper describes a class of differential games on networks. The construction of cooperative optimality principles using a special type of characteristic function that takes into account the network structure of the game is investigated. The core, the Shapley value and the tau-value are used as cooperative optimality principles. The results are demonstrated on a model of a differential research investment game, where the Shapley value and the tau-value are explicitly constructed.

scholarly journals XBP1 links the 12-hour clock to NAFLD and regulation of membrane fluidity and lipid homeostasis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Huan Meng ◽  
Naomi M. Gonzales ◽  
David M. Lonard ◽  
Nagireddy Putluri ◽  
Bokai Zhu ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Membrane Fluidity ◽  
Phospholipid Composition ◽  
Cellular Membrane ◽  
Lipid Homeostasis ◽  
Alcoholic Fatty Liver ◽  
The Core ◽  
Metabolic Genes ◽  
Rate Limiting ◽  
Alcoholic Fatty Liver Disease

AbstractA distinct 12-hour clock exists in addition to the 24-hour circadian clock to coordinate metabolic and stress rhythms. Here, we show that liver-specific ablation of X-box binding protein 1 (XBP1) disrupts the hepatic 12-hour clock and promotes spontaneous non-alcoholic fatty liver disease (NAFLD). We show that hepatic XBP1 predominantly regulates the 12-hour rhythmicity of gene transcription in the mouse liver and demonstrate that perturbation of the 12-hour clock, but not the core circadian clock, is associated with the onset and progression of this NAFLD phenotype. Mechanistically, we provide evidence that the spliced form of XBP1 (XBP1s) binds to the hepatic 12-hour cistrome to directly regulate the 12-hour clock, with a periodicity paralleling the harmonic activation of the 12-hour oscillatory transcription of many rate-limiting metabolic genes known to have perturbations in human metabolic disease. Functionally, we show that Xbp1 ablation significantly reduces cellular membrane fluidity and impairs lipid homeostasis via rate-limiting metabolic processes in fatty acid monounsaturated and phospholipid remodeling pathways. These findings reveal that genetic disruption of the hepatic 12-hour clock links to the onset and progression of NAFLD development via transcriptional regulator XBP1, and demonstrate a role for XBP1 and the 12-hour clock in the modulation of phospholipid composition and the maintenance of lipid homeostasis.

Achilles-Mediated and Sex-Specific Regulation of Circadian mRNA Rhythms in Drosophila

2019 ◽  
Vol 34 (2) ◽  
pp. 131-143 ◽  
Author(s):  
Jiajia Li ◽  
Renee Yin Yu ◽  
Farida Emran ◽  
Brian E. Chen ◽  
Michael E. Hughes
Keyword(s):  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Clock Genes ◽  
Peripheral Tissues ◽  
Knock Down ◽  
Rhythmic Expression ◽  
The Core ◽  
Physiological Processes ◽  
Specific Regulation

The circadian clock is an evolutionarily conserved mechanism that generates the rhythmic expression of downstream genes. The core circadian clock drives the expression of clock-controlled genes, which in turn play critical roles in carrying out many rhythmic physiological processes. Nevertheless, the molecular mechanisms by which clock output genes orchestrate rhythmic signals from the brain to peripheral tissues are largely unknown. Here we explored the role of one rhythmic gene, Achilles, in regulating the rhythmic transcriptome in the fly head. Achilles is a clock-controlled gene in Drosophila that encodes a putative RNA-binding protein. Achilles expression is found in neurons throughout the fly brain using fluorescence in situ hybridization (FISH), and legacy data suggest it is not expressed in core clock neurons. Together, these observations argue against a role for Achilles in regulating the core clock. To assess its impact on circadian mRNA rhythms, we performed RNA sequencing (RNAseq) to compare the rhythmic transcriptomes of control flies and those with diminished Achilles expression in all neurons. Consistent with previous studies, we observe dramatic upregulation of immune response genes upon knock-down of Achilles. Furthermore, many circadian mRNAs lose their rhythmicity in Achilles knock-down flies, suggesting that a subset of the rhythmic transcriptome is regulated either directly or indirectly by Achilles. These Achilles-mediated rhythms are observed in genes involved in immune function and in neuronal signaling, including Prosap, Nemy and Jhl-21. A comparison of RNAseq data from control flies reveals that only 42.7% of clock-controlled genes in the fly brain are rhythmic in both males and females. As mRNA rhythms of core clock genes are largely invariant between the sexes, this observation suggests that sex-specific mechanisms are an important, and heretofore under-appreciated, regulator of the rhythmic transcriptome.

scholarly journals Structural and Spatial Associations between Fe, O, and C in the Network Structure of the Leptothrix ochracea Sheath Surface

2011 ◽  
Vol 77 (21) ◽  
pp. 7873-7875 ◽  
Author(s):  
Tomoko Suzuki ◽  
Hideki Hashimoto ◽  
Hiromichi Ishihara ◽  
Tomonari Kasai ◽  
Hitoshi Kunoh ◽  
...  
Keyword(s):  
Network Structure ◽  
Outer Coat ◽  
Content Type ◽  
Spatial Associations ◽  
The Core ◽  
Bacterial Origin ◽  
Gallionella Ferruginea

ABSTRACTThe structural and spatial associations of Fe with O and C in the outer coat fibers of theLeptothrix ochraceasheath were shown to be substantially similar to the stalk fibers ofGallionella ferruginea, i.e., a central C core, probably of bacterial origin, and aquatic Fe interacting with O at the surface of the core.

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