6,391 research outputs found

    Prolamin content and grain weight in RNAi silenced wheat lines under different conditions of temperature and nitrogen availability

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    Temperature and nitrogen (N) availability are two important environmental factors that may produce important changes in grain composition during grain filling of bread wheat. In this study, four wheat lines with the down-regulation of gliadins by means of RNA interference (RNAi) have been characterized to determine the effect of thermal stress and N availability on grain weight and quality; with focus on gliadin and glutenin protein fractions. Grain weight was reduced with heat stress (HS) in all RNAi lines, whereas gliadin content was increased in the wild-types. With respect to gliadin content, RNAi lines responded to HS and N availability differently from their respective wild-types, except for ω-gliadin content, indicating a very clear stability of silencing under different environmental conditions. In a context of increased temperature and HS events, and in environments with different N availability, the RNAi lines with down-regulated gliadins seem well suited for the production of wheat grain with low gliadin content.The Spanish Ministry of Economy and Competitiveness (Project AGL2016-80566-P) and the European Regional Development Fund (FEDER) supported this research

    Optimisation of Isolation Methods for the AZA Group of Marine Biotoxins and the Development of Accurate and Precise Methods of Analysis

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    The two main groups of biotoxins which affect the Irish shellfish industry are azaspiracids (AZAs) and the okadaic acid (OA) group (OA, DTX2, DTX1 and their esters) toxins. Since AZAs were first identified in 1998, well over 30 analogues have been reported. Structural and toxicological data have been described for AZA1–5 (isolated from shellfish). LC-MS/MS is the EU reference method for detection of the AZAs (AZA1, -2 and -3) and the OA group toxins in raw shellfish with the regulatory limit set at 160 μg/kg for each toxin group. Limited supplies of purified toxins for certified reference materials (CRMs) were available for AZA1−3. Little knowledge was also available on the relevance of the additional AZA analogues that had been reported, in terms of human health protection. The analysis of marine biotoxins by LC-MS/MS can be severely affected by matrix interferences. Here, a study was performed on two instruments; a quadrapole time of flight (QToF) and a triple stage quadrupole (TSQ) to assess matrix interferences for AZA1 and OA using a number of tissue types. Enhancement was observed for OA on the QToF while matrix suppression was observed for AZA1 on TSQ. The enhancement on the QToF was overcome by use of an on-line SPE method and matrix matched calibrants, while the suppression on the TSQ was found to be due to late eluting compounds from previous injections and was overcome by employing either a column flush method or an alkaline mobile phase. The isolation of 11 AZA analogues (AZA1−10 and 37-epi-AZA1) from shellfish using an improved procedure (7 steps) is described. Recoveries increased ~2-fold (~ 52%) from previously described isolation procedures. The preparative isolation procedure developed for shellfish was optimised for Azadinium spinosum bulk culture extracts such that only four steps were necessary to obtain purified AZA1 and -2. A purification efficiency of ~70% was achieved, and isolation from 1,200 L of culture yielded 9.3 mg of AZA1 and 2.2 mg of AZA2 (purities \u3e95%)

    Development of a QuEChERS method for simultaneous analysis of 3-Monochloropropane-1,2-diol monoesters and Glycidyl esters in edible oils and margarine by LC-APCI-MS/MS

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    A simple, fast and effective direct method based on HPLC-APCI-QqQ-MS/MS has been developed to simultaneously determine four 3-monochloropropane-1,2-diol monoesters (3-MCPDE) esterified with palmitic, linoleic, stearic, and oleic acid, and two glycidyl esters (GE) with palmitic and oleic acid in margarine and olive oil using a QuEChERS approach. Factors affecting the efficiency of the extraction process were assessed, including type and amount of salt, extraction solvent, test portion amount, and clean-up sorbent. The analytical method was validated according to Food and Drug Administration (FDA) guidelines using matrix-matched calibration with internal standards and showed good results in terms of linearity (r2 > 0.9992), accuracy (80<Recovery<120%), and precision (RSD<15%). The method was successfully applied for the first time to 11 margarine samples for simultaneous analysis of 3-MCPDE and GEThis work was supported by the Spanish Ministry of Science, Innovation, and Universities (Project RTI2018‐096450‐B‐I00) and FEDER fundsS

    Towards identification of a non-abelian state: observation of a quarter of electron charge at ν=5/2\nu=5/2 quantum Hall state

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    The fractional quantum Hall effect, where plateaus in the Hall resistance at values of coexist with zeros in the longitudinal resistance, results from electron correlations in two dimensions under a strong magnetic field. Current flows along the edges carried by charged excitations (quasi particles) whose charge is a fraction of the electron charge. While earlier research concentrated on odd denominator fractional values of ν\nu, the observation of the even denominator ν=5/2\nu=5/2 state sparked a vast interest. This state is conjectured to be characterized by quasiparticles of charge e/4, whose statistics is non-abelian. In other words, interchanging of two quasi particles may modify the state of the system to an orthogonal one, and does not just add a phase as in for fermions or bosons. As such, these quasiparticles may be useful for the construction of a topological quantum computer. Here we report data of shot noise generated by partitioning edge currents in the ν=5/2\nu=5/2 state, consistent with the charge of the quasiparticle being e/4, and inconsistent with other potentially possible values, such as e/2 and e. While not proving the non-abelian nature of the ν=5/2\nu=5/2 state, this observation is the first step toward a full understanding of these new fractional charges

    A strong immune response in young adult honeybees masks their increased susceptibility to infection compared to older bees

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    Honeybees, Apis mellifera, show age-related division of labor in which young adults perform maintenance ("housekeeping") tasks inside the colony before switching to outside foraging at approximately 23 days old. Disease resistance is an important feature of honeybee biology, but little is known about the interaction of pathogens and age-related division of labor. We tested a hypothesis that older forager bees and younger "house" bees differ in susceptibility to infection. We coupled an infection bioassay with a functional analysis of gene expression in individual bees using a whole genome microarray. Forager bees treated with the entomopathogenic fungus Metarhizium anisopliae s.l. survived for significantly longer than house bees. This was concomitant with substantial differences in gene expression including genes associated with immune function. In house bees, infection was associated with differential expression of 35 candidate immune genes contrasted with differential expression of only two candidate immune genes in forager bees. For control bees (i.e. not treated with M. anisopliae) the development from the house to the forager stage was associated with differential expression of 49 candidate immune genes, including up-regulation of the antimicrobial peptide gene abaecin, plus major components of the Toll pathway, serine proteases, and serpins. We infer that reduced pathogen susceptibility in forager bees was associated with age-related activation of specific immune system pathways. Our findings contrast with the view that the immunocompetence in social insects declines with the onset of foraging as a result of a trade-off in the allocation of resources for foraging. The up-regulation of immune-related genes in young adult bees in response to M. anisopliae infection was an indicator of disease susceptibility; this also challenges previous research in social insects, in which an elevated immune status has been used as a marker of increased disease resistance and fitness without considering the effects of age-related development

    Dissecting interferon-induced transcriptional programs in human peripheral blood cells

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    Interferons are key modulators of the immune system, and are central to the control of many diseases. The response of immune cells to stimuli in complex populations is the product of direct and indirect effects, and of homotypic and heterotypic cell interactions. Dissecting the global transcriptional profiles of immune cell populations may provide insights into this regulatory interplay. The host transcriptional response may also be useful in discriminating between disease states, and in understanding pathophysiology. The transcriptional programs of cell populations in health therefore provide a paradigm for deconvoluting disease-associated gene expression profiles.We used human cDNA microarrays to (1) compare the gene expression programs in human peripheral blood mononuclear cells (PBMCs) elicited by 6 major mediators of the immune response: interferons alpha, beta, omega and gamma, IL12 and TNFalpha; and (2) characterize the transcriptional responses of purified immune cell populations (CD4+ and CD8+ T cells, B cells, NK cells and monocytes) to IFNgamma stimulation. We defined a highly stereotyped response to type I interferons, while responses to IFNgamma and IL12 were largely restricted to a subset of type I interferon-inducible genes. TNFalpha stimulation resulted in a distinct pattern of gene expression. Cell type-specific transcriptional programs were identified, highlighting the pronounced response of monocytes to IFNgamma, and emergent properties associated with IFN-mediated activation of mixed cell populations. This information provides a detailed view of cellular activation by immune mediators, and contributes an interpretive framework for the definition of host immune responses in a variety of disease settings

    The Telecommunications and Data Acquisition Report

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    This quarterly publication provides archival reports on developments in programs in space communications, radio navigation, radio science, and ground-based radio and radar astronomy. It reports on activities of the Deep Space Network (DSN) in planning, supporting research and technology, implementation, and operations. Also included are standardization activities at the Jet Propulsion Laboratory for space data and information systems

    A computer implementation of an orthonormal expansion method for digital image noise suppression

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    Images are usually corrupted by noise which comes from various sources: noise in the recording media (e.g. film grain noise), and noise introduced in the transmission channel. Noise degrades the visual quality of images and obscures the detail information in the images. One of the major sources of noise for images recorded on films is film grain noise. An orthonormal expansion algorithm for digital image noise suppression is implemented. The objective is to preserve as much sharpness and produce as few artifacts in the processed image as possible. The method sections an image into non-overlapping blocks. Each block is treated as a matrix which is decomposed as a sum of outer products of its singular vectors. The coefficient of each outer product is modified by a scaling function and the matrix is reconstructed. The resulting image shows a reduction of noise. The two major problems in the method are: 1. the blocking artifacts due to the sectioned processing, and, 2. the trade-off between the suppression of noise and the loss of sharpness. By separating the image into the low frequency and the high frequency components and processing only the latter component, the method is able to reduce the blocking artifacts to an invisible level. To obtain the optimal trade-off between the suppression of noise and the loss of sharpness, systematic variations of the coefficient scaling function were used to process the image. The best choice of the scaling function is found to be [ 1 - (σi / ai ) 3 ] which is a little different from the least-square-error estimate, [ 1 - (σi / ai ) 2 ]
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