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11.
Environmentally transmitted pathogens face ecological interactions (e.g., competition, predation, parasitism) in the outside-host environment and host immune system during infection. Despite the ubiquitousness of environmental opportunist pathogens, traditional epidemiology focuses on obligatory pathogens incapable of environmental growth. Here we ask how competitive interactions in the outside-host environment affect the dynamics of an opportunist pathogen. We present a model coupling the classical SI and Lotka–Volterra competition models. In this model we compare a linear infectivity response and a sigmoidal infectivity response. An important assumption is that pathogen virulence is traded off with competitive ability in the environment. Removing this trade-off easily results in host extinction. The sigmoidal response is associated with catastrophic appearances of disease outbreaks when outside-host species richness, or overall competition pressure, decreases. This indicates that alleviating outside-host competition with antibacterial substances that also target the competitors can have unexpected outcomes by providing benefits for opportunist pathogens. These findings may help in developing alternative ways of controlling environmental opportunist pathogens. 相似文献
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Vinod Jani Uddhavesh B. Sonavane Rajendra Joshi 《Journal of biomolecular structure & dynamics》2013,31(6):845-860
Abstract Reaching the experimental time scale of millisecond is a grand challenge for protein folding simulations. The development of advanced Molecular Dynamics techniques like Replica Exchange Molecular Dynamics (REMD) makes it possible to reach these experimental timescales. In this study, an attempt has been made to reach the multi microsecond simulation time scale by carrying out folding simulations on a three helix bundle protein, Villin, by combining REMD and Amber United Atom model. Twenty replicas having different temperatures ranging from 295 K to 390 K were simulated for 1.5 μs each. The lowest Root Mean Square Deviation (RMSD) structure of 2.5 Å was obtained with respect to native structure (PDB code 1VII), with all the helices formed. The folding population landscapes were built using segment-wise RMSD and Principal Components as reaction coordinates. These analyses suggest the two-stage folding for Villin. The combination of REMD and Amber United Atom model may be useful to understand the folding mechanism of various fast folding proteins 相似文献
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The phytosociological affiliation of Tephroseris longifolia subsp. moravica, species of European importance, was studied in relation to two closely related species of the genus Tephroseris which have overlapping distribution within the Western Carpathian Mts: T. intergrifolia and T. crispa. The main aim was to compare plant communities inhabited by the three taxa, to assess the major environmental gradients responsible for variation in their distribution and to estimate ecological indicator values for Tephroseris longifolia subsp. moravica. T. longifolia subsp. moravica was recorded in nine localities in the Slovakia and Czech Republic where it occurs in very specific site conditions of ecotone habitats. Its phytosociological affiliation is restricted to grasslands of the alliances Bromion erecti and Arrhenatherion elatioris and to the ecotone vegetation between these grasslands and beech forests. T. integrifolia occurs most frequently in the Diantho lumnitzeri-Seslerion, Bromion erecti and Quercion pubescenti-petraeae alliances. T. crispa occurs predominantly in communities of the Calthion palustris alliance and Scheuchzerio-Caricetea fuscae, Mulgedio-Aconitetea and Montio-Cardaminetea classes. The major gradient responsible for variation in species composition of communities inhabited by the studied taxa was associated with moisture and nutrient content. The vascular plant-based ecological indicator values for Tephroseris longifolia subsp. moravica calculated from phytosociological relevés with its occurrence were set for light — 6, temperature — 5, continentality — 4, moisture — 5, soil reaction — 6 and nutrients — 5. We conclude that the studied taxon has intermediate relationship to the most of the studied factors in comparison with two related species, T. crispa and T. integrifolia. 相似文献
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Hamid Manzoor Jani Kelloniemi Annick Chiltz David Wendehenne Alain Pugin Benoit Poinssot Angela Garcia‐Brugger 《The Plant journal : for cell and molecular biology》2013,76(3):466-480
Like their animal counterparts, plant glutamate receptor‐like (GLR) homologs are intimately associated with Ca2+ influx through plasma membrane and participate in various physiological processes. In pathogen‐associated molecular patterns (PAMP)‐/elicitor‐mediated resistance, Ca2+ fluxes are necessary for activating downstream signaling events related to plant defense. In this study, oligogalacturonides (OGs), which are endogenous elicitors derived from cell wall degradation, were used to investigate the role of Arabidopsis GLRs in defense signaling. Pharmacological investigations indicated that GLRs are partly involved in free cytosolic [Ca2+] ([Ca2+]cyt) variations, nitric oxide (NO) production, reactive oxygen species (ROS) production and expression of defense‐related genes by OGs. In addition, wild‐type Col‐0 plants treated with the glutamate‐receptor antagonist 6,7‐dinitriquinoxaline‐2,3‐dione (DNQX) had a compromised resistance to Botrytis cinerea and Hyaloperonospora arabidopsidis. Moreover, we provide genetic evidence that AtGLR3.3 is a key component of resistance against H. arabidopsidis. In addition, some OGs‐triggered immune events such as defense gene expression, NO and ROS production are also to different extents dependent on AtGLR3.3. Taken together, these data provide evidence for the involvement of GLRs in elicitor/pathogen‐mediated plant defense signaling pathways in Arabidopsis thaliana. 相似文献
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KB Cullberg T Christiansen SK Paulsen JM Bruun SB Pedersen B Richelsen 《Obesity (Silver Spring, Md.)》2013,21(3):454-460
Background:
Vascular growth is a prerequisite for adipose tissue (AT) development and expansion. Some AT cytokines and hormones have effects on vascular development, like vascular endothelial growth factor (VEGF‐A), angiopoietin (ANG‐1), ANG‐2 and angiopoietin‐like protein‐4 (ANGPTL‐4).Methods:
In this study, the independent and combined effects of diet‐induced weight loss and exercise on AT gene expression and proteins levels of those angiogenic factors were investigated. Seventy‐nine obese males and females were randomized to: 1. Exercise‐only (EXO; 12‐weeks exercise without diet‐restriction), 2. Hypocaloric diet (DIO; 8‐weeks very low energy diet (VLED) + 4‐weeks weight maintenance diet) and 3. Hypocaloric diet and exercise (DEX; 8‐weeks VLED + 4‐weeks weight maintenance diet combined with exercise throughout the 12 weeks). Blood samples and fat biopsies were taken before and after the intervention.Results:
Weight loss was 3.5 kg in the EXO group and 12.3 kg in the DIO and DEX groups. VEGF‐A protein was non‐significantly reduced in the weight loss groups. ANG‐1 protein levels were significantly reduced 22‐25% after all three interventions (P < 0.01). The ANG‐1/ANG‐2 ratio was also decreased in all three groups (P < 0.05) by 27‐38%. ANGPTL‐4 was increased in the EXO group (15%, P < 0.05) and 9% (P < 0.05) in the DIO group. VEGF‐A, ANG‐1, and ANGPTL‐4 were all expressed in human AT, but only ANGPTL‐4 was influenced by the interventions.Conclusions:
Our data show that serum VEGF‐A, ANG‐1, ANG‐2, and ANGPTL‐4 levels are influenced by weight changes, indicating the involvement of these factors in the obese state. Moreover, it was found that weight loss generally was associated with a reduced angiogenic activity in the circulation. 相似文献18.
Scott Geibel Kassahun Habtamu Gebeyehu Mekonnen Nrupa Jani Lynnette Kay Julyata Shibru Lake Bedilu Samuel Kalibala 《PloS one》2016,11(2)
Objective
Evaluate the reliability and validity of the Youth Self-Report (YSR) as a screening tool for mental health problems among young people vulnerable to HIV in Ethiopia.Design
A cross-sectional assessment of young people currently receiving social services.Methods
Young people age 15–18 participated in a study where a translated and adapted version of the YSR was administered by trained nurses, followed by an assessment by Ethiopian psychiatrists. Internal reliability of YSR syndrome scales were assessed using Chronbach''s alpha. Test-retest reliability was assessed through repeating the YSR one month later. To assess validity, analysis of the sensitivity and specificity of the YSR compared to the psychiatrist assessment was conducted.Results
Across the eight syndrome scales, the YSR best measured the diagnosis of anxiety/depression and social problems among young women, and attention problems among young men. Among individual YSR syndrome scales, internal reliability ranged from unacceptable (Chronback’s alpha = 0.11, rule-breaking behavior among young women) to good (α≥0.71, anxiety/depression among young women). Anxiety/depression scores of ≥8.5 among young women also had good sensitivity (0.833) and specificity (0.754) to predict a true diagnosis. The YSR syndrome scales for social problems among young women and attention problems among young men also had fair consistency and validity measurements. Most YSR scores had significant positive correlations between baseline and post-one month administration. Measures of reliability and validity for most other YSR syndrome scales were fair to poor.Conclusions
The adapted, personally administered, Amharic version of the YSR has sufficient reliability and validity in identifying young vulnerable women with anxiety/depression and/or social problems, and young men with attention problems; which were the most common mental health disorders observed by psychiatrists among the migrant populations in this study. Further assessment of the applicability of the YSR among vulnerable young people for less common disorders in Ethiopia is needed. 相似文献19.
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