1,264 research outputs found
Absorption Studies of the Ni(4--Methylpyridine)\u3csub\u3e4 \u3c/sub\u3e(SCN)\u3csub\u3e2\u3c/sub\u3e A˙ C\u3csub\u3e6\u3c/sub\u3eH\u3csub\u3e6\u3c/sub\u3e Clathrate System
Impact of Tumor-Derived CCL2 on Macrophage Effector Function
Monocyte chemoattractant protein-1 (MCP-1, CCL2) is produced by many different types of cells. In the current investigation, the effect of tumor-derived CCL2 on macrophages was evaluated to determine the extent to which this chemokine influenced the innate immune response to cancer. To do this, we used the 4T1 murine mammary carcinoma cell line that constitutively expresses CCL2 and generated 4T1 expressing an antisense CCL2 transcript. The antisense-CCL2-expressing 4T1 produced no detectable CCL2. Macrophages from female BALB/c mice were exposed to supernatants from these tumor cells. The results showed that tumor-derived CCL2 was capable of modulating cytokine gene expression but not protein production in resting, activated, and tumor-associated macrophages. In addition, tumor-derived CCL2 did not affect phagocytic activity, nitric oxide production, or cytolytic activity of the macrophages. Overall, these data suggest that tumor-derived CCL2 does not directly influence macrophage-mediated antitumor activity
Plant infection by two different viruses induce contrasting changes of vectors fitness and behavior
Abstract Insect-vectored plant viruses can induce changes in plant phenotypes, thus influencing plant?vector interactions in a way that may promote their dispersal according to their mode of transmission (i.e., circulative vs. noncirculative). This indirect vector manipulation requires host?virus?vector coevolution and would thus be effective solely in very specific plant?virus?vector species associations. Some studies suggest this manipulation may depend on multiple factors relative to various intrinsic characteristics of vectors such as transmission efficiency. In anintegrative study, we tested the effects of infection of the Brassicaceae Camelina sativa with the noncirculative Cauliflower mosaic virus (CaMV) or the circulative Turnip yellows virus (TuYV) on the host-plant colonization of two aphid species differing in their virus transmission efficiency: the polyphagous Myzus persicae, efficient vector of both viruses, and the Brassicaceae specialist Brevicoryne brassicae, poor vector of TuYV and efficient vector of CaMV. Results confirmed the important role of virus mode of transmission as plant-mediated effects of CaMV on the two aphid species induced negative alterations of feeding behavior (i.e., decreased phloem sap ingestion) and performance that were both conducive for virus fitness by promoting dispersion after a rapid acquisition. In addition, virus transmission efficiency may also play a role in vector manipulation by viruses as only the responses of the efficient vector to plant-mediated effects of TuYV, that is, enhanced feeding behavior and performances, were favorable to their acquisition and further dispersal. Altogether, this work demonstrated that vector transmission efficiency also has to be considered when studying the mechanisms underlying vector manipulation by viruses. Our results also reinforce the idea that vector manipulation requires coevolution between plant, virus and vector
Argon I lines produced in a hollow cathode source, 332 nm to 5865 nm
We report precision measurements by
Fourier transform spectroscopy of the
vacuum wavenumber, line width, and relative
signal strength of 928 lines in the
Ar I spectrum. Wavelength in air and classification
of the transition are supplied for
each line. A comparison of our results with
other precision measurements illustrates
the sensitivity of Ar I wavelengths to conditions
in the light source
In-situ Analysis of Laminated Composite Materials by X-ray Micro-Computed Tomography and Digital Volume Correlation
The complex mechanical behaviour of composite materials, due to internal heterogeneity and multi-layered composition impose deeper studies. This paper presents an experimental investigation technique to perform volume kinematic measurements in composite materials. The association of X-ray micro-computed tomography acquisitions and Digital Volume Correlation (DVC) technique allows the measurement of displacements and deformations in the whole volume of composite specimen. To elaborate the latter, composite fibres and epoxy resin are associated with metallic particles to create contrast during X-ray acquisition.
A specific in situ loading device is presented for three-point bending tests, which enables the visualization of transverse shear effects in composite structures
Solid polymer fuel cell synthesis by low pressure plasmas: a short review
In this review, we report on the use of low pressure plasmas for elaborating materials at the heart of solid polymer fuel cells (SPFC), especially electrodes and the membrane electrolyte. Electrodes are formed using plasma sputtering techniques while the ion conducting membranes are built up using plasma polymerization. Fuel cell performance will be improved by these approaches. The electrode catalyst profile is optimized while membrane working temperature is increased and methanol crossover is lowered compared to conventional PEM fuel cells.We gratefully thank GdR 2479 PACEM, Université d'Orléans,
SPI-CNRS, ACI ECD 2004 (Ministry of Research) for grants
and constant support
A Laser Frequency Comb System for Absolute Calibration of the VTT Echelle Spectrograph
A wavelength calibration system based on a laser frequency comb (LFC) was
developed in a co-operation between the Kiepenheuer-Institut f\"ur
Sonnenphysik, Freiburg, Germany and the Max-Planck-Institut f\"ur Quantenoptik,
Garching, Germany for permanent installation at the German Vacuum Tower
Telescope (VTT) on Tenerife, Canary Islands. The system was installed
successfully in October 2011. By simultaneously recording the spectra from the
Sun and the LFC, for each exposure a calibration curve can be derived from the
known frequencies of the comb modes that is suitable for absolute calibration
at the meters per second level. We briefly summarize some topics in solar
physics that benefit from absolute spectroscopy and point out the advantages of
LFC compared to traditional calibration techniques. We also sketch the basic
setup of the VTT calibration system and its integration with the existing
echelle spectrograph.Comment: 9 pages, 2 figures; Solar Physics 277 (2012
Php4 Is a Key Player for Iron Economy in Meiotic and Sporulating Cells
Meiosis is essential for sexually reproducing organisms, including the fission yeast Schizosaccharomyces
pombe. In meiosis, chromosomes replicate once in a diploid precursor cell (zygote), and then
segregate twice to generate four haploid meiotic products, named spores in yeast. In S. pombe, Php4 is
responsible for the transcriptional repression capability of the heteromeric CCAAT-binding factor to negatively
regulate genes encoding iron-using proteins under low-iron conditions. Here, we show that the
CCAAT-regulatory subunit Php4 is required for normal progression of meiosis under iron-limiting conditions.
Cells lacking Php4 exhibit a meiotic arrest at metaphase I. Microscopic analyses of cells expressing
functional GFP-Php4 show that it colocalizes with chromosomal material at every stage of meiosis under low
concentrations of iron. In contrast, GFP-Php4 fluorescence signal is lost when cells undergo meiosis under
iron-replete conditions. Global gene expression analysis of meiotic cells using DNA microarrays identified
137 genes that are regulated in an iron- and Php4-dependent manner. Among them, 18 genes are
expressed exclusively during meiosis and constitute new putative Php4 target genes, which include
hry1+ and mug14+. Further analysis validates that Php4 is required for maximal and timely repression of
hry1+ and mug14+ genes. Using a chromatin immunoprecipitation approach, we show that Php4 specifically
associates with hry1+ and mug14+ promoters in vivo. Taken together, the results reveal that in iron-starved
meiotic cells, Php4 is essential for completion of the meiotic program since it participates in global gene
expression reprogramming to optimize the use of limited available iron
Synthesising, using, and correcting for telluric features in high-resolution astronomical spectra
We present a technique to synthesise telluric absorption and emission
features both for in-situ wavelength calibration and for their removal from
astronomical spectra. While the presented technique is applicable for a wide
variety of optical and infrared spectra, we concentrate in this paper on
selected high-resolution near-infrared spectra obtained with the CRIRES
spectrograph to demonstrate its performance and limitation. We find that
synthetic spectra reproduce telluric absorption features to about 2%, even
close to saturated line cores. Thus, synthetic telluric spectra could be used
to replace the observation of telluric standard stars, saving valuable
observing time. This technique also provides a precise in-situ wavelength
calibration, especially useful for high-resolution near-infrared spectra in the
absence of other calibration sources.Comment: 11 pages, 11 figures, accepted for publication in A&A (updated
version
Short-term, high-fat diet accelerates disuse atrophy and protein degradation in a muscle-specific manner in mice
Background:
A short-term high-fat diet impairs mitochondrial function and the ability of skeletal muscle to respond to growth stimuli, but it is unknown whether such a diet alters the ability to respond to atrophy signals. The purpose of this study was to determine whether rapid weigh gain induced by a high-fat (HF) diet accelerates denervation-induced muscle atrophy.
Methods:
Adult, male mice (C57BL/6) were fed a control or HF (60Â % calories as fat) diet for 3Â weeks (3wHF). Sciatic nerve was sectioned unilaterally for the final 5 or 14Â days of the diet. Soleus and extensor digitorum longus (EDL) muscles were removed and incubated in vitro to determine rates of protein degradation and subsequently homogenized for determination of protein levels of LC3, ubiquitination, myosin heavy chain (MHC) distribution, and mitochondrial subunits.
Results:
When mice were fed the 3wHF diet, whole-body fat mass more than doubled, but basal (innervated) muscle weights, rates of protein degradation, LC3 content, mitochondrial protein content, and myosin isoform distribution were not significantly different than with the control diet in either soleus or EDL. However in the 14Â day denervated soleus, the 3wHF diet significantly augmented loss of mass, proteolysis rate, amount of the autophagosome marker LC3 II, and the amount of overall ubiquitination as compared to the control fed mice. On the contrary, the 3wHF diet had no significant effect in the EDL on amount of mass loss, proteolysis rate, LC3 levels, or ubiquitination. Fourteen days denervation also induced a loss of mitochondrial proteins in the soleus but not the EDL, regardless of the diet.
Conclusions:
Taken together, a short-term, high-fat diet augments denervation muscle atrophy by induction of protein degradation in the mitochondria-rich soleus but not in the glycolytic EDL. These findings suggest that the denervation-induced loss of mitochondria and HF diet-induced impairment of mitochondrial function may combine to promote skeletal muscle atrophy
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