625 research outputs found
Evidence for transfer followed by breakup in 7Li + 65Cu
The observation of a large cross-section for the alpha + d channel compared
to breakup into the alpha + t channel from an exclusive measurement for the
7Li+65Cu system at 25 MeV is presented. A detailed analysis of the angular
distribution using coupled channels Born approximation calculations has
provided clear evidence that the observed alpha + d events arise from a two
step process, i.e. direct transfer to the 2.186 MeV (3+) resonance in the alpha
+ d continuum of 6Li followed by breakup, and are not due to final state
interaction effects.Comment: 12 pages, 3 figures, To be published in Phys. Letts.
The impact of capital structure on the decision to outsource with long term contracts
This paper analyzes how capital structure affects the firms’ strategic choice between outsourcing with long term contracts and outsourcing to the spot market. When outsourcing to the spot market firms are exposed to price uncertainty, whereas a long term contract allows them to set in advance the outsourcing price. We show that, to the extent that leverage and uncertainty can lead to financial distress costs in bad states of nature, firms may use long term contracts as a risk management device to hedge input price uncertainty.N/
The histone chaperones Vps75 and Nap1 form ring-like, tetrameric structures in solution
NAP-1 fold histone chaperones play an important role in escorting histones to and from sites of nucleosome assembly and disassembly. The two NAP-1 fold histone chaperones in budding yeast, Vps75 and Nap1, have previously been crystalized in a characteristic homodimeric conformation. In this study, a combination of small angle X-ray scattering, multi angle light scattering and pulsed electron–electron double resonance approaches were used to show that both Vps75 and Nap1 adopt ring-shaped tetrameric conformations in solution. This suggests that the formation of homotetramers is a common feature of NAP-1 fold histone chaperones. The tetramerisation of NAP-1 fold histone chaperones may act to shield acidic surfaces in the absence of histone cargo thus providing a ‘self-chaperoning’ type mechanism
Family-specific, novel, deleterious germline variants provide a rich resource to identify genetic predispositions for BRCAx familial breast cancer
BACKGROUND: Genetic predisposition is the primary risk factor for familial breast cancer. For the majority of familial breast cancer, however, the genetic predispositions remain unknown. All newly identified predispositions occur rarely in disease population, and the unknown genetic predispositions are estimated to reach up to total thousands. Family unit is the basic structure of genetics. Because it is an autosomal dominant disease, individuals with a history of familial breast cancer must carry the same genetic predisposition across generations. Therefore, focusing on the cases in lineages of familial breast cancer, rather than pooled cases in disease population, is expected to provide high probability to identify the genetic predisposition for each family. METHODS: In this study, we tested genetic predispositions by analyzing the family-specific variants in familial breast cancer. Using exome sequencing, we analyzed three families and 22 probands with BRCAx (BRCA-negative) familial breast cancer. RESULTS: We observed the presence of family-specific, novel, deleterious germline variants in each family. Of the germline variants identified, many were shared between the disease-affected family members of the same family but not found in different families, which have their own specific variants. Certain variants are putative deleterious genetic predispositions damaging functionally important genes involved in DNA replication and damaging repair, tumor suppression, signal transduction, and phosphorylation. CONCLUSIONS: Our study demonstrates that the predispositions for many BRCAx familial breast cancer families can lie in each disease family. The application of a family-focused approach has the potential to detect many new predispositions
Bats Use Magnetite to Detect the Earth's Magnetic Field
While the role of magnetic cues for compass orientation has been confirmed in numerous animals, the mechanism of detection is still debated. Two hypotheses have been proposed, one based on a light dependent mechanism, apparently used by birds and another based on a “compass organelle” containing the iron oxide particles magnetite (Fe3O4). Bats have recently been shown to use magnetic cues for compass orientation but the method by which they detect the Earth's magnetic field remains unknown. Here we use the classic “Kalmijn-Blakemore” pulse re-magnetization experiment, whereby the polarity of cellular magnetite is reversed. The results demonstrate that the big brown bat Eptesicus fuscus uses single domain magnetite to detect the Earths magnetic field and the response indicates a polarity based receptor. Polarity detection is a prerequisite for the use of magnetite as a compass and suggests that big brown bats use magnetite to detect the magnetic field as a compass. Our results indicate the possibility that sensory cells in bats contain freely rotating magnetite particles, which appears not to be the case in birds. It is crucial that the ultrastructure of the magnetite containing magnetoreceptors is described for our understanding of magnetoreception in animals
Amylase/trypsin-inhibitor content and inhibitory activity of German common wheat landraces and modern varieties do not differ
Amylase/trypsin-inhibitors (ATIs) are triggers for wheat-related disorders like baker’s asthma and non-celiac wheat sensitivity. With the rise of wheat-related disorders among the population, the hypothesis that breeding may have resulted in changes in the protein composition of wheat was put forward. The ATI content of 14 German common wheat landraces and six modern varieties harvested in three consecutive years was analyzed by liquid chromatography–tandem mass spectrometry, and the inhibitory activity against α-amylase was measured with an enzymatic assay. The mean ATI content and proportion of crude protein of both groups did not differ. There were also only small differences in the content and proportion of single ATIs. The mean values for the inhibitory activity of both groups were also similar. These results indicate that breeding might not have led to changes in the protein composition and landraces are unlikely to be better tolerated than modern varieties
Protein composition and bread volume of German common wheat landraces grown under organic conditions
Landraces are genetically heterogeneous plant populations that are regionally particularly well adapted to the natural and cultural agricultural environment. Their genetic memory originates from pre-industrial agriculture and food production with consequences for their agronomic and processing performance. Since wheat-related disorders have increased in the population, breeding might have resulted in changes in the protein composition. The aim of this study was to investigate the protein composition and baking quality of 14 German common wheat landraces. Six modern varieties served as a control group. The protein composition was determined using modified Osborne fractionation and reversed-phase high-performance liquid chromatography. In addition, the water absorption and bread volume were determined.
The crude protein content, proportions of albumins and globulins, water absorption and bread volume did not differ between modern varieties and landraces. The proportion of gliadins was higher in landraces (64.0%) compared to modern varieties (57.6%), whereas the proportion of glutenins was lower in landraces (17.4%) than in modern varieties (22.0%). The same observation was made for the respective gluten protein types except the proportion of ω1,2-gliadins, where there was no difference between the two groups. This resulted in a significantly higher ratio of gliadins to glutenins of 4.3 in landraces compared to 2.8 in the modern varieties, but no difference in the total gluten proportion. Taken together, there was no clear distinction between landraces and modern varieties. However, a few landraces such as Roter Sächsischer Landweizen showed similar characteristics to modern varieties and are therefore interesting for further investigations
The EFF-1A Cytoplasmic Domain Influences Hypodermal Cell Fusions in C. elegans But Is Not Dependent on 14-3-3 Proteins.
BACKGROUND: Regulatory and biophysical mechanisms of cell-cell fusion are largely unknown despite the fundamental requirement for fused cells in eukaryotic development. Only two cellular fusogens that are not of clear recent viral origin have been identified to date, both in nematodes. One of these, EFF-1, is necessary for most cell fusions in Caenorhabditis elegans. Unregulated EFF-1 expression causes lethality due to ectopic fusion between cells not developmentally programmed to fuse, highlighting the necessity of tight fusogen regulation for proper development. Identifying factors that regulate EFF-1 and its paralog AFF-1 could lead to discovery of molecular mechanisms that control cell fusion upstream of the action of a membrane fusogen. Bioinformatic analysis of the EFF-1A isoform\u27s predicted cytoplasmic domain (endodomain) previously revealed two motifs that have high probabilities of interacting with 14-3-3 proteins when phosphorylated. Mutation of predicted phosphorylation sites within these motifs caused measurable loss of eff-1 gene function in cell fusion in vivo. Moreover, a human 14-3-3 isoform bound to EFF-1::GFP in vitro. We hypothesized that the two 14-3-3 proteins in C. elegans, PAR-5 and FTT-2, may regulate either localization or fusion-inducing activity of EFF-1.
METHODOLOGY/PRINCIPAL FINDINGS: Timing of fusion events was slightly but significantly delayed in animals unable to produce full-length EFF-1A. Yet, mutagenesis and live imaging showed that phosphoserines in putative 14-3-3 binding sites are not essential for EFF-1::GFP accumulation at the membrane contact between fusion partner cells. Moreover, although the EFF-1A endodomain was required for normal rates of eff-1-dependent epidermal cell fusions, reduced levels of FTT-2 and PAR-5 did not visibly affect the function of wild-type EFF-1 in the hypodermis.
CONCLUSIONS/SIGNIFICANCE: Deletion of the EFF-1A endodomain noticeably affects the timing of hypodermal cell fusions in vivo. However, prohibiting phosphorylation of candidate 14-3-3-binding sites does not impact localization of the fusogen. Hypodermal membrane fusion activity persists when 14-3-3 expression levels are reduced
Biochemical evidence linking the GIX thymocyte surface antigen to the gp69/71 envelope glycoprotein of murine leukemia virus.
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