2,721 research outputs found

    Host coenzyme Q redox state is an early biomarker of thermal stress in the coral Acropora millepora

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    © 2015 Lutz et al.This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Bleaching episodes caused by increasing seawater temperatures may induce mass coral mortality and are regarded as one of the biggest threats to coral reef ecosystems worldwide. The current consensus is that this phenomenon results from enhanced production of harmful reactive oxygen species (ROS) that disrupt the symbiosis between corals and their endosymbiotic dinoflagellates, Symbiodinium. Here, the responses of two important antioxidant defence components, the host coenzyme Q (CoQ) and symbiont plastoquinone (PQ) pools, are investigated for the first time in colonies of the scleractinian coral, Acropora millepora, during experimentally-induced bleaching under ecologically relevant conditions. Liquid chromatography-mass spectrometry (LC-MS) was used to quantify the states of these two pools, together with physiological parameters assessing the general state of the symbiosis (including photosystem II photochemical efficiency, chlorophyll concentration and Symbiodinium cell densities). The results show that the responses of the two antioxidant systems occur on different timescales: (i) the redox state of the Symbiodinium PQ pool remained stable until twelve days into the experiment, after which there was an abrupt oxidative shift; (ii) by contrast, an oxidative shift of approximately 10% had occurred in the host CoQ pool after 6 days of thermal stress, prior to significant changes in any other physiological parameter measured. Host CoQ pool oxidation is thus an early biomarker of thermal stress in corals, and this antioxidant pool is likely to play a key role in quenching thermally-induced ROS in the coral-algal symbiosis. This study adds to a growing body of work that indicates host cellular responses may precede the bleaching process and symbiont dysfunction

    Yukawa potentials in systems with partial periodic boundary conditions I : Ewald sums for quasi-two dimensional systems

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    Yukawa potentials are often used as effective potentials for systems as colloids, plasmas, etc. When the Debye screening length is large, the Yukawa potential tends to the non-screened Coulomb potential ; in this small screening limit, or Coulomb limit, the potential is long ranged. As it is well known in computer simulation, a simple truncation of the long ranged potential and the minimum image convention are insufficient to obtain accurate numerical data on systems. The Ewald method for bulk systems, i.e. with periodic boundary conditions in all three directions of the space, has already been derived for Yukawa potential [cf. Y., Rosenfeld, {\it Mol. Phys.}, \bm{88}, 1357, (1996) and G., Salin and J.-M., Caillol, {\it J. Chem. Phys.}, \bm{113}, 10459, (2000)], but for systems with partial periodic boundary conditions, the Ewald sums have only recently been obtained [M., Mazars, {\it J. Chem. Phys.}, {\bf 126}, 056101 (2007)]. In this paper, we provide a closed derivation of the Ewald sums for Yukawa potentials in systems with periodic boundary conditions in only two directions and for any value of the Debye length. A special attention is paid to the Coulomb limit and its relation with the electroneutrality of systems.Comment: 40 pages, 5 figures and 4 table

    HIV Types, Groups, Subtypes and Recombinant Forms: Errors in Replication, Selection Pressure and Quasispecies

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    HIV-1 is a chimpanzee virus which was transmitted to humans by several zoonotic events resulting in infection with HIV-1 groups M P, and in parallel transmission events from sooty mangabey monkey viruses leading to infections with HIV-2 groups A H. Both viruses have circulated in the human population for about 80 years. In the infected patient, HIV mutates, and by elimination of some of the viruses by the action of the immune system individual quasispecies are formed. Along with the selection of the fittest viruses, mutation and recombination after superinfection with HIV from different groups or subtypes have resulted in the diversity of their patterns of geographic distribution. Despite the high variability observed, some essential parts of the HIV genome are highly conserved. Viral diversity is further facilitated in some parts of the HIV genome by drug selection pressure and may also be enhanced by different genetic factors, including HLA in patients from different regions of the world. Viral and human genetic factors influence pathogenesis. Viral genetic factors are proteins such as Tat, Vif and Rev. Human genetic factors associated with a better clinical outcome are proteins such as APOBEC, langerin, tetherin and chemokine receptor 5 (CCR5) and HLA B27, B57, DRB1{*}1303, KIR and PARD3B. Copyright (C) 2012 S. Karger AG, Base

    The Cosmic Infrared Background: Measurements and Implications

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    The cosmic infrared background records much of the radiant energy released by processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In the past few years, data from the Cosmic Background Explorer mission provided the first measurements of this background, with additional constraints coming from studies of the attenuation of TeV gamma-rays. At the same time there has been rapid progress in resolving a significant fraction of this background with the deep galaxy counts at infrared wavelengths from the Infrared Space Observatory instruments and at submillimeter wavelengths from the Submillimeter Common User Bolometer Array instrument. This article reviews the measurements of the infrared background and sources contributing to it, and discusses the implications for past and present cosmic processes.Comment: 61 pages, incl. 9 figures, to be published in Annual Reviews of Astronomy and Astrophysics, 2001, Vol. 3

    Facial expressions depicting compassionate and critical emotions: the development and validation of a new emotional face stimulus set

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    Attachment with altruistic others requires the ability to appropriately process affiliative and kind facial cues. Yet there is no stimulus set available to investigate such processes. Here, we developed a stimulus set depicting compassionate and critical facial expressions, and validated its effectiveness using well-established visual-probe methodology. In Study 1, 62 participants rated photographs of actors displaying compassionate/kind and critical faces on strength of emotion type. This produced a new stimulus set based on N = 31 actors, whose facial expressions were reliably distinguished as compassionate, critical and neutral. In Study 2, 70 participants completed a visual-probe task measuring attentional orientation to critical and compassionate/kind faces. This revealed that participants lower in self-criticism demonstrated enhanced attention to compassionate/kind faces whereas those higher in self-criticism showed no bias. To sum, the new stimulus set produced interpretable findings using visual-probe methodology and is the first to include higher order, complex positive affect displays

    Evaluation of the nutrition knowledge of sports department students of universities

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    <p>Abstract</p> <p>Background</p> <p>Individuals who have knowledge on the importance of adequate and balanced diet and reflect this knowledge to their behaviors are considered to be more successful in sports life. The present study aims to evaluate the nutrition knowledge of students receiving sports education in universities.</p> <p>Methods</p> <p>The study sample consists of 343 voluntary students from the Sports Departments of Hacettepe, Gazi and Ankara Universities in Ankara. The questionnaire used in the study included a demographic section, and 30 questions on true-false nutrition knowledge. For the reliability of the questionnaire, the internal consistency coefficient was calculated and the Kuder Richardson (KR-20) value was found to be 0.71. For higher reliability, 9 dysfunctional questions were excluded from the questionnaire. The research data were collected through a questionnaire form and face-to-face interviews. For the statistical analyses of the data, tables were prepared to show mean, standard deviation (<inline-formula><m:math xmlns:m="http://www.w3.org/1998/Math/MathML" name="1550-2783-8-11-i1"><m:mover accent="true"><m:mrow><m:mi>X</m:mi></m:mrow><m:mo class="MathClass-op">̄</m:mo></m:mover><m:mo class="MathClass-bin">±</m:mo><m:mi>S</m:mi><m:mi>D</m:mi></m:math></inline-formula>) and percentage (%) values. In order to determine the nutrition knowledge of students, the "independent t test" was used for nutrition lesson and gender.</p> <p>Results</p> <p>University students receiving sports education and expected to continue their professional lives on sport-related fields were determined to have the lack of knowledge on nutrition. The mean value about the nutrition knowledge of the first year students was found 11.150 ± 2.962, while the mean value of the fourth year students was 13.460 ± 3.703, and the difference is statistically significant (p = .000).</p> <p>Conclusion</p> <p>Students, coaches and teachers in physical education were found not to give the necessary importance to their diets, and they were still not aware of the importance of nutrition on performance.</p

    Effect of Differential N-linked and O-linked Mannosylation on Recognition of Fungal Antigens by Dendritic Cells

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    BACKGROUND. An experimental approach for improving vaccine efficacy involves targeting antigens to mannose receptors (MRs) on dendritic cells (DCs) and other professional antigen presenting cells. Previously, we demonstrated that mannosylated Pichia pastoris-derived recombinant proteins exhibited increased immunogenicity compared to proteins lacking mannosylation. In order to gain insight into the mechanisms responsible for this observation, the present study examined the cellular uptake of the mannosylated and deglycosylated recombinant proteins. METHODOLOGY/PRINCIPAL FINDINGS. Utilizing transfected cell lines, roles for the macrophage mannose receptor (MMR, CD206) and DC-SIGN (CD209) in the recognition of the mannosylated, but not deglycosylated, antigens were demonstrated. The uptake of mannosylated antigens into murine bone marrow-derived DCs (BMDCs) was inhibited by yeast mannans (YMs), suggesting a mannose-specific C-type lectin receptor-dependent process, while the uptake of deglycosylated antigens remained unaffected. In particular, antigens with both N-linked and extensive O-linked mannosylation showed the highest binding and uptake by BMDCs. Finally, confocal microscopy studies revealed that both mannosylated and deglycosylated P. pastoris-derived recombinant proteins localized in MHC class II+ compartments within BMDCs. CONCLUSIONS/SIGNIFICANCE. Taken together with our previous results, these data suggest that increased uptake by mannose-specific C-type lectin receptors is the major mechanism responsible for the enhanced antigenicity seen with mannosylated proteins. These findings have important implications for vaccine design and contribute to our understanding of how glycosylation affects the immune response to eukaryotic pathogens.National Institutes of Health (RO1 AI25780, RO1 AI37532

    SHIP-Deficient Dendritic Cells, Unlike Wild Type Dendritic Cells, Suppress T Cell Proliferation via a Nitric Oxide-Independent Mechanism

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    Dendritic cells (DCs) not only play a crucial role in activating immune cells but also suppressing them. We recently investigated SHIP's role in murine DCs in terms of immune cell activation and found that TLR agonist-stimulated SHIP-/- GM-CSF-derived DCs (GM-DCs) were far less capable than wild type (WT, SHIP+/+) GM-DCs at activating T cell proliferation. This was most likely because SHIP-/- GM-DCs could not up-regulate MHCII and/or co-stimulatory receptors following TLR stimulation. However, the role of SHIP in DC-induced T cell suppression was not investigated.In this study we examined SHIP's role in DC-induced T cell suppression by co-culturing WT and SHIP-/- murine DCs, derived under different conditions or isolated from spleens, with αCD3+ αCD28 activated WT T cells and determined the relative suppressive abilities of the different DC subsets. We found that, in contrast to SHIP+/+ and -/- splenic or Flt3L-derived DCs, which do not suppress T cell proliferation in vitro, both SHIP+/+ and -/- GM-DCs were capable of potently suppressing T cell proliferation. However, WT GM-DC suppression appeared to be mediated, at least in part, by nitric oxide (NO) production while SHIP-/- GM-DCs expressed high levels of arginase 1 and did not produce NO. Following exhaustive studies to ascertain the mechanism of SHIP-/- DC-mediated suppression, we could conclude that cell-cell contact was required and the mechanism may be related to their relative immaturity, compared to SHIP+/+ GM-DCs.These findings suggest that although both SHIP+/+ and -/- GM-DCs suppress T cell proliferation, the mechanism(s) employed are different. WT GM-DCs suppress, at least in part, via IFNγ-induced NO production while SHIP-/- GM-DCs do not produce NO and suppression can only be alleviated when contact is prevented

    Psychometric Properties of the German Version of the Child Post-Traumatic Cognitions Inventory (CPTCI-GER)

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    Dysfunctional trauma-related cognitions are associated with posttraumatic stress disorder (PTSD). The psychometric properties of the German version of the Child Post-Traumatic Cognitions Inventory (CPTCI-GER) were assessed in a sample of 223 children and adolescents (7–16 years) with a history of different traumatic events. Confirmatory factor analyses supported the original two-factor structure—permanent and disturbing change (CPTCI-PC) and fragile person in a scary world (CPTCI-SW). The total scale and both subscales showed good internal consistency. Participants with PTSD had significantly more dysfunctional trauma-related cognitions than those without PTSD. Dysfunctional posttraumatic cognitions correlated significantly with posttraumatic stress symptoms (PTSS; r = .62), depression (r = .71), and anxiety (r = .67). The CPTCI-GER has good psychometric properties and may facilitate evaluation of treatments and further research on the function of trauma-related cognitions in children and adolescents. (Partial) correlations provide empirical support for the combined DSM-5 symptom cluster negative alterations in cognitions and mood

    STAR: predicting recombination sites from amino acid sequence

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    BACKGROUND: Designing novel proteins with site-directed recombination has enormous prospects. By locating effective recombination sites for swapping sequence parts, the probability that hybrid sequences have the desired properties is increased dramatically. The prohibitive requirements for applying current tools led us to investigate machine learning to assist in finding useful recombination sites from amino acid sequence alone. RESULTS: We present STAR, Site Targeted Amino acid Recombination predictor, which produces a score indicating the structural disruption caused by recombination, for each position in an amino acid sequence. Example predictions contrasted with those of alternative tools, illustrate STAR'S utility to assist in determining useful recombination sites. Overall, the correlation coefficient between the output of the experimentally validated protein design algorithm SCHEMA and the prediction of STAR is very high (0.89). CONCLUSION: STAR allows the user to explore useful recombination sites in amino acid sequences with unknown structure and unknown evolutionary origin. The predictor service is available from
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