Search results for "Stability."
showing 10 items of 3015 documents
Models of SHS: An overview
2007
International audience; The theoretical models of SHS based on lamellar or cellular approximations of the heterogeneous reactive media are comparatively analyzed. It is shown that the ratio of the reaction time to the characteristic time of heat transfer between particles is a decisive parameter for the combustion wave propagation. When the time of reaction is shorter than the time of heat exchange, the combustion occurs in a discrete mode; in the opposite case, a quasi-homogeneous combustion mode occurs. Development of the discrete cellular model does not discard the quasi-homogeneous approach but markedly extends the scope of combustion theory. This extension enables explanation of many o…
Hidden attractors in dynamical models of phase-locked loop circuits : limitations of simulation in MATLAB and SPICE
2017
During recent years it has been shown that hidden oscillations, whose basin of attraction does not overlap with small neighborhoods of equilibria, may significantly complicate simulation of dynamical models, lead to unreliable results and wrong conclusions, and cause serious damage in drilling systems, aircrafts control systems, electromechanical systems, and other applications. This article provides a survey of various phase-locked loop based circuits (used in satellite navigation systems, optical, and digital communication), where such difficulties take place in MATLAB and SPICE. Considered examples can be used for testing other phase-locked loop based circuits and simulation tools, and m…
HSP110 promotes colorectal cancer growth through STAT3 activation.
2017
IF 7.932; International audience; Heat shock protein 110 (HSP110) is induced by different stresses and, through its anti-apoptotic and chaperoning properties, helps cells survive these adverse situations. In colon cancers, HSP110 is abnormally abundant. We have recently shown that colorectal cancer patients with microsatellite instability (MSI) had an improved response to chemotherapy because they harbor an HSP110-inactivating mutation (HSP110DE9). In this work, we used patient biopsies, human colorectal cancer cells grown in vitro and in vivo (xenografts), and intestinal crypts to demonstrate that HSP110 is also involved in colon cancer growth. We showed that HSP110 induces colon cancer ce…
Evidence for the Existence of an Effective Interfacial Tension between Miscible Fluids: Isobutyric Acid-Water and 1-Butanol-Water in a Spinning-Drop …
2006
We report definitive evidence for an effective interfacial tension between two types of miscible fluids using spinning-drop tensiometry (SDT). Isobutyric acid (IBA) and water have an upper critical solution temperature (UCST) of 26.3 degrees C. We created a drop of the IBA-rich phase in the water-rich phase below the UCST and then increased the temperature above it. Long after the fluids have reached thermal equilibrium, the drop persists. By plotting the inverse of the drop radius cubed (r(-)(3)) vs the rotation rate squared (omega(2)), we confirmed that an interfacial tension exists and estimated its value. The transition between the miscible fluids remained sharp instead of becoming more…
On the stability of the localized single-valued extension property under commuting perturbations
2013
This article concerns the permanence of the single-valued extension property at a point under suitable perturbations. While this property is, in general, not preserved under sums and products of commuting operators, we obtain positive results in the case of commuting perturbations that are quasi-nilpotent, algebraic, or Riesz operators.
Yeast contains multiple forms of histone acetyltransferase.
1989
We have assayed several methods to quantitatively recover yeast histone acetyltransferases in an attempt to study the multiplicity of enzymatic activities. Two methods, namely (NH4)2SO4 precipitation and salt dissociation of chromatin in 0.5 M NaCl, yielded convenient preparations of total histone acetyltransferases. DEAE-Sepharose chromatography of the crude extracts resulted in the separation of three peaks of activity when total yeast histones were used as substrate. However, the scanning of the enzymatic activity toward individual histones along the chromatography, achieved by determining the specific activity of the individual histones after incubating whole histones and [14C]acetyl-Co…
Recruitment of Xrn1 to stress-induced genes allows efficient transcription by controlling RNA polymerase II backtracking
2020
A new paradigm has emerged proposing that the crosstalk between nuclear transcription and cytoplasmic mRNA stability keeps robust mRNA levels in cells under steady-state conditions. A key piece in this crosstalk is the highly conserved 5′–3′ RNA exonuclease Xrn1, which degrades most cytoplasmic mRNAs but also associates with nuclear chromatin to activate transcription by not well-understood mechanisms. Here, we investigated the role of Xrn1 in the transcriptional response of Saccharomyces cerevisiae cells to osmotic stress. We show that a lack of Xrn1 results in much lower transcriptional induction of the upregulated genes but in similar high levels of their transcripts because of parallel …
The relative importance of transcription rate, cryptic transcription and mRNA stability on shaping stress responses in yeast
2012
It has been recently stated that stress-responding genes in yeast are enriched in cryptic transcripts and that this is the cause of the differences observed between mRNA amount and RNA polymerase occupancy profiles. Other studies have shown that such differences are mainly due to modulation of mRNA stabilities. Here we analyze the relationship between the presence of cryptic transcripts in genes and their stress response profiles. Despite some of the stress-responding gene groups being indeed enriched in specific classes of cryptic transcripts, we found no statistically significant evidence that cryptic transcription is responsible for the differences observed between mRNA and transcription…
Rpb4 and Puf3 imprint and post-transcriptionally control the stability of a common set of mRNAs in yeast
2020
ABSTRACTGene expression involving RNA polymerase II is regulated by the concerted interplay between mRNA synthesis and degradation, crosstalk in which mRNA decay machinery and transcription machinery respectively impact transcription and mRNA stability. Rpb4, and likely dimer Rpb4/7, seem the central components of the RNA pol II governing these processes. In this work we unravel the molecular mechanisms participated by Rpb4 that mediate the posttranscriptional events regulating mRNA imprinting and stability. By RIP-Seq, we analyzed genome-wide the association of Rpb4 with mRNAs and demonstrated that it targeted a large population of more than 1400 transcripts. A group of these mRNAs was als…
Impact of High pH Stress on Yeast Gene Expression: A Comprehensive Analysis of mRNA Turnover During Stress Responses.
2015
Environmental alkalinisation represents a stress condition for yeast Saccharomyces cerevisiae, to which this organism responds with extensive gene expression remodelling. We show here that alkaline pH causes an overall decrease in the transcription rate (TR) and a fast destabilisation of mRNAs, followed by a more prolonged stabilisation phase. In many cases, augmented mRNA levels occur without the TR increasing, which can be attributed to mRNA stabilisation. In contrast, the reduced amount of mRNAs is contributed by both a drop in the TR and mRNA stability. A comparative analysis with other forms of stress shows that, unlike high pH stress, heat-shock, osmotic and oxidative stresses present…