1,227 research outputs found
Differential Interleukin-2 Transcription Kinetics Render Mouse but Not Human T Cells Vulnerable to Splicing Inhibition Early after Activation
T cells are nodal players in the adaptive immune response against pathogens and malignant cells. Alternative splicing plays a crucial role in T cell activation, which is analyzed mainly at later time points upon stimulation. Here we have discovered a 2-h time window early after stimulation where optimal splicing efficiency or, more generally, gene expression efficiency is crucial for successful T cell activation. Reducing the splicing efficiency at 4 to 6 h poststimulation significantly impaired murine T cell activation, which was dependent on the expression dynamics of the Egr1-Nab2-interleukin-2 (IL-2) pathway. This time window overlaps the time of peak IL-2 de novo transcription, which, we suggest, represents a permissive time window in which decreased splicing (or transcription) efficiency reduces mature IL-2 production, thereby hampering murine T cell activation. Notably, the distinct expression kinetics of the Egr1-Nab2-IL-2 pathway between mouse and human render human T cells refractory to this vulnerability. We propose that the rational temporal modulation of splicing or transcription during peak de novo expression of key effectors can be used to fine-tune stimulation-dependent biological outcomes. Our data also show that critical consideration is required when extrapolating mouse data to the human system in basic and translational research
Long slit spectroscopy of NH2 in comets Halley, Wilson, and Nishikawa-Takamizawa-Tago
Long-slit spectra of comets Halley, Wilson and Nishikawa-Takamizawa-Tago were obtained with the 3.9 meter Anglo-Australian Telescope. Spectra of comets Halley and Wilson were obtained with the IPCS at a spectral resolution of 0.5 A and a spatial resolution of 10(exp 3) km. Spectra of comets Wilson and Nishikawa-Takamizawa-Tago were obtained with a CCD at a spectral resolution of 1.5 A and a spatial resolution of approximately 3 x 10(exp 3) km. Surface brightness profiles for NH2 were extracted from the long-slit spectra of each comet. The observed surface brightness profiles extend along the slit to approximately 6 x 10(exp 4) km from the nucleus in both sunward and tailward directions. By comparing surface distribution calculated from an appropriate coma model with observed surface brightness distributions, the photodissociation timescale of the parent molecule of NH2 can be inferred. The observed NH2 surface brightness profiles in all three comets compares well with a surface brightness profile calculated using the vectorial model, an NH3 photodissociation timescale of 7 x 10(exp 3) seconds, and an NH2 photodissociation timescale of 34,000 seconds
Developmental stage-specific regulation of the circadian Clock by Temperature in Zebrafish
The circadian clock enables animals to adapt their physiology and behaviour in anticipation of the day-night cycle. Light and temperature represent two key environmental timing cues (zeitgebers) able to reset this mechanism and so maintain its synchronization with the environmental cycle. One key challenge is to unravel how the regulation of the clock by zeitgebers matures during early development. The zebrafish is an ideal model for studying circadian clock ontogeny since the process of development occurs ex utero in an optically transparent chorion and many tools are available for genetic analysis. However, the role played by temperature in regulating the clock during zebrafish development is poorly understood. Here, we have established a clock-regulated luciferase reporter transgenic zebrafish line (Tg (−3.1) per1b::luc) to study the effects of temperature on clock entrainment. We reveal that under complete darkness, from an early developmental stage onwards (48 to 72 hpf), exposure to temperature cycles is a prerequisite for the establishment of self-sustaining rhythms of zfper1b, zfaanat2, and zfirbp expression and also for circadian cell cycle rhythms. Furthermore, we show that following the 5–9 somite stage, the expression of zfper1b is regulated by acute temperature shifts
Hybrid functional study of proper and improper multiferroics
We present a detailed study of the structural, electronic, magnetic and
ferroelectric properties of prototypical \textit{proper} and \textit{improper}
multiferroic (MF) systems such as BiFeO and orthorhombic HoMnO,
respectively, within density functional theory (DFT) and using the
Heyd-Scuseria-Ernzerhof hybrid functional (HSE). By comparing our results with
available experimental data as well as with state-of-the-art GW calculations,
we show that the HSE formalism is able to account well for the relevant
properties of these compounds and it emerges as an accurate tool for predictive
first-principles investigations on multiferroic systems. We show that effects
beyond local and semilocal DFT approaches (as provided by HSE) are necessary
for a realistic description of MFs. For the electric polarization, a decrease
is found for MFs with magnetically-induced ferroelectricity, such as HoMnO,
where the calculated polarization changes from 6 using
Perdew-Burke-Ernzerhof (PBE) to 2 using HSE. However, for
\textit{proper} MFs, such as BiFeO, the polarization slightly increases
upon introduction of exact exchange. Our findings therefore suggest that a
general trend for the HSE correction to bare density functional cannot be
extracted; rather, a specific investigation has to be carried out on each
compound.Comment: Revised version. In press in PCC
Characterization of SiGe/Ge heterostructures and graded layers using variable angle spectroscopic ellipsometry
Variable angle spectroscopic ellipsometry (VASE) has been used to characterize Si(x)Ge(1-x)/Ge superlattices (SLs) grown on Ge substrates and thick Si(x)Ge(1-x)/Ge heterostructures grown on Si substrates. Our VASE analysis yielded the thicknesses and alloy compositions of all layers within the optical penetration depth of the surface. In addition, strain effects were observed in the VASE results for layers under both compressive and tensile strain. Results for the SL structures were found to be in close agreement with high resolution x-ray diffraction measurements made on the same samples. The VASE analysis has been upgraded to characterize linearly graded Si(x)Ge(1-x) buffer layers. The algorithm has been used to determine the total thickness of the buffer layer along with the start and end alloy composition by breaking the total thickness into many (typically more than 20) equal layers. Our ellipsometric results for 1 (mu)m buffer layers graded in the ranges 0.7 less than or = x less than or = 1.0, and 0.5 less than or = x less than or = 1.0 are presented, and compare favorably with the nominal values
Alternative splicing coupled mRNA decay shapes the temperature‐dependent transcriptome
Mammalian body temperature oscillates with the time of the dayand is altered in diverse pathological conditions. We recently iden-tified a body temperature-sensitive thermometer-like kinase,which alters SR protein phosphorylation and thereby globallycontrols alternative splicing (AS). AS can generate unproductivevariants which are recognized and degraded by diverse mRNAdecay pathways—including nonsense-mediated decay (NMD). Herewe show extensive coupling of body temperature-controlled AS tomRNA decay, leading to global control of temperature-dependentgene expression (GE). Temperature-controlled, decay-inducingsplicing events are evolutionarily conserved and pervasively foundwithin RNA-binding proteins, including most SR proteins. AS-coupledpoison exon inclusion is essential for rhythmic GE of SR proteins andhas a global role in establishing temperature-dependent rhythmicGE profiles, both in mammals under circadian body temperaturecycles and in plants in response to ambient temperature changes.Together, these data identify body temperature-driven AS-coupledmRNA decay as an evolutionary ancient, core clock-independentmechanism to generate rhythmic GE
Quality of obstetric care in the sparsely populated sub-arctic area of Norway 2009-2011
Background: It is challenging to obtain high quality obstetric care in a sparsely populated area. In the subarctic region of Norway, significant distances, weather conditions and seasonable darkness have called for a decentralized care model. We aimed to explore the quality of this care. Methods: A retrospective study employing data (2009–11) from the Medical Birth Registry of Norway was initiated. Northern Norwegian and Norwegian figures were compared. Midwife administered maternity units, departments at local and regional specialist hospitals were compared. National registry data on post-caesarean wound infection (2009–2010) was added. Quality of care was measured as rate of multiple pregnancies, caesarean section, post-caesarean wound infection, Apgar score < 7, birth weight < 2.5 kilos, perineal rupture, stillbirth, eclampsia, pregnancy induced diabetes and vacuum or forceps assisted delivery. There were 15,586 births in 15 delivery units. Results: Multiple pregnancies were less common in northern Norway (1.3 vs. 1.7%) (P = 0.02). Less use of vacuum (6.6% vs. 8.3%) (P = 0.01) and forceps (0.9% vs 1.7%) (P < 0.01) assisted delivery was observed. There was no difference with regard to pregnancy induced diabetes, caesarean section, stillbirth, Apgar score < 7 and eclampsia. A significant difference in birth weight < 2.5 kilos (4.7% vs. 5.0%) (P < 0.04) and perineal rupture grade 3 and 4 (1.5% vs. 2.3%) (P < 0.02) were revealed. The post-caesarean wound infection rate was higher (10.5% vs. 7.4%) (P < 0.01). Conclusion: Northern Norway had an obstetric care of good quality. Birth weight, multiple pregnancies and post-caesarean wound infection rates should be further elucidated
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