Project description:Tseng2012 - Circadian clock of N.crassa A comprehensive model of the circardian clock of fungal Neurospora crassa , which encompasses existing knowledge of the biochemistry of Neurospora clock, is described by Tseng et al. (2012). The model is validated against a wide range of experimental phenotypes and has been used to investigate possible molecular explanations of temperature compensation. This model is described in the article: Comprehensive modelling of the Neurospora circadian clock and its temperature compensation. Tseng YY, Hunt SM, Heintzen C, Crosthwaite SK, Schwartz JM PLoS Comput. Biol. [2012 ; Volume: 8 (Issue: 3 )] Page info: e1002437 Abstract: Circadian clocks provide an internal measure of external time allowing organisms to anticipate and exploit predictable daily changes in the environment. Rhythms driven by circadian clocks have a temperature compensated periodicity of approximately 24 hours that persists in constant conditions and can be reset by environmental time cues. Computational modelling has aided our understanding of the molecular mechanisms of circadian clocks, nevertheless it remains a major challenge to integrate the large number of clock components and their interactions into a single, comprehensive model that is able to account for the full breadth of clock phenotypes. Here we present a comprehensive dynamic model of the Neurospora crassa circadian clock that incorporates its key components and their transcriptional and post-transcriptional regulation. The model accounts for a wide range of clock characteristics including: a periodicity of 21.6 hours, persistent oscillation in constant conditions, arrhythmicity in constant light, resetting by brief light pulses, and entrainment to full photoperiods. Crucial components influencing the period and amplitude of oscillations were identified by control analysis. Furthermore, simulations enabled us to propose a mechanism for temperature compensation, which is achieved by simultaneously increasing the translation of frq RNA and decreasing the nuclear import of FRQ protein. Figure 3 of the reference publication has been reproduced using Copasi 4.8 (Build 35). This model is hosted on BioModels Database and identified by: MODEL1212150000 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Gould2011 - Temperature Sensitive Circadian Clock This model is a temperature sensitive version of Pokhilko et al. 2010 (PMID: 20865009), which is BIOMD0000000273 in BioModels. This model is described in the article: Network balance via CRY signalling controls the Arabidopsis circadian clock over ambient temperatures. Gould PD, Ugarte N, Domijan M, Costa M, Foreman J, Macgregor D, Rose K, Griffiths J, Millar AJ, Finkenstädt B, Penfield S, Rand DA, Halliday KJ, Hall AJ. Mol. Syst. Biol. 2013; 9: 650 Abstract: Circadian clocks exhibit 'temperature compensation', meaning that they show only small changes in period over a broad temperature range. Several clock genes have been implicated in the temperature-dependent control of period in Arabidopsis. We show that blue light is essential for this, suggesting that the effects of light and temperature interact or converge upon common targets in the circadian clock. Our data demonstrate that two cryptochrome photoreceptors differentially control circadian period and sustain rhythmicity across the physiological temperature range. In order to test the hypothesis that the targets of light regulation are sufficient to mediate temperature compensation, we constructed a temperature-compensated clock model by adding passive temperature effects into only the light-sensitive processes in the model. Remarkably, this model was not only capable of full temperature compensation and consistent with mRNA profiles across a temperature range, but also predicted the temperature-dependent change in the level of LATE ELONGATED HYPOCOTYL, a key clock protein. Our analysis provides a systems-level understanding of period control in the plant circadian oscillator. This model is hosted on BioModels Database and identified by: BIOMD0000000564. To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models. To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:There is growing appreciation that the feeling of well-being, alterations in mood and susceptibility to a variety of medical disorders depend on the proper expression of the master circadian clock and the synchrony among the other oscillators found in many peripheral tissues. To improve our understanding of the role of peripheral oscillators, an improved understanding of the molecular machinery sub-serving the circadian variation in gene expression is essential. Our long-term goal is to understand the molecular mechanisms that initiate circadian gene expression following external stimulation in the mammalian pineal gland. Are all or just some of the "circadian clock" genes induced by NE, cAMP, or cGMP? In this project we compare a series of gene expression patterns using DNA microarray in response to cAMP, cGMP and NE stimulation to understand why NE does not initiate circadian rhythms in the rat pineal gland. As a preliminary experiment we will compare gene expression 0, 1, and 4 h after start of chemical stimulation. A failure of NE to initiate circadian rhythms is due to failure of activation of certain "circadian clock" genes. We found that circadian rhythms are initiated by stimulation of cAMP or cGMP analogue in the rat pineal gland, while norepinephrine (NE) stimulation only moderately induce Period1 mRNA (one of "circadian clock" genes) 24 h after start of stimulation. From these results we hypothesize that external stimulation activates some "circadian clock" genes simultaneously, and that failure of circadian rhythm initiation following NE stimulation is due to insufficient "circadian clock" genes activations. Male rats of wistar strain are kept in 12h-12h light dark cycles at least for one week before start of experiments. Pineal glands are removed from animals and placed in the culture dish. Rat pineal glands are cultured for 3 days before chemical stimulation. On the day of experiment, the pineal cultures are stimulated using one of NE, cAMP and cGMP analogues for 1 or 4 h before harvest. The samples are immediately frozen and total RNA are extracted from each group which are from a pool of 8 pineal glands using Trizol reagent (Invitrogen). Concentrations of total RNA are determined using spectrophotometer, and six microgram of total RNA is aliquoted in each sample tube for further analysis. Since we already have Affymetrix Rat Genome U34A array GeneChips, we would like to send Chips as well as our total RNA samples. Experiment Overall Design: as above

Project description:There is growing appreciation that the feeling of well-being, alterations in mood and susceptibility to a variety of medical disorders depend on the proper expression of the master circadian clock and the synchrony among the other oscillators found in many peripheral tissues. To improve our understanding of the role of peripheral oscillators, an improved understanding of the molecular machinery sub-serving the circadian variation in gene expression is essential. Our long-term goal is to understand the molecular mechanisms that initiate circadian gene expression following external stimulation in the mammalian pineal gland. Are all or just some of the "circadian clock" genes induced by NE, cAMP, or cGMP? In this project we compare a series of gene expression patterns using DNA microarray in response to cAMP, cGMP and NE stimulation to understand why NE does not initiate circadian rhythms in the rat pineal gland. As a preliminary experiment we will compare gene expression 0, 1, and 4 h after start of chemical stimulation. A failure of NE to initiate circadian rhythms is due to failure of activation of certain "circadian clock" genes. We found that circadian rhythms are initiated by stimulation of cAMP or cGMP analogue in the rat pineal gland, while norepinephrine (NE) stimulation only moderately induce Period1 mRNA (one of "circadian clock" genes) 24 h after start of stimulation. From these results we hypothesize that external stimulation activates some "circadian clock" genes simultaneously, and that failure of circadian rhythm initiation following NE stimulation is due to insufficient "circadian clock" genes activations. Male rats of wistar strain are kept in 12h-12h light dark cycles at least for one week before start of experiments. Pineal glands are removed from animals and placed in the culture dish. Rat pineal glands are cultured for 3 days before chemical stimulation. On the day of experiment, the pineal cultures are stimulated using one of NE, cAMP and cGMP analogues for 1 or 4 h before harvest. The samples are immediately frozen and total RNA are extracted from each group which are from a pool of 8 pineal glands using Trizol reagent (Invitrogen). Concentrations of total RNA are determined using spectrophotometer, and six microgram of total RNA is aliquoted in each sample tube for further analysis. Since we already have Affymetrix Rat Genome U34A array GeneChips, we would like to send Chips as well as our total RNA samples. Keywords: time-course

			Action	DRS
	L_E_F230613_08_SO_Nc_wt1_cont.pep.xml	Pepxml
	L_E_F230613_08_SO_Nc_wt1_cont.raw	Raw
	L_E_F230613_12_SO_Nc_R1_samp.pep.xml	Pepxml
	L_E_F230613_12_SO_Nc_samp.raw	Raw
	L_E_F230613_13_SO_Nc_R2_samp.pep.xml	Pepxml

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Conserved function of a RasGEF-mediated pathway in the metabolic compensation of the circadian clock

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Conserved function of a RasGEF-mediated pathway in the metabolic compensation of the circadian clock.

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