86 research outputs found
Facultative Symbiont Infections Affect Aphid Reproduction
Some bacterial symbionts alter their hosts reproduction through various mechanisms that enhance their transmission in the host population. In addition to its obligatory symbiont Buchnera aphidicola, the pea aphid Acyrthosiphon pisum harbors several facultative symbionts influencing several aspects of host ecology. Aphids reproduce by cyclical parthenogenesis whereby clonal and sexual reproduction alternate within the annual life cycle. Many species, including the pea aphid, also show variation in their reproductive mode at the population level, with some lineages reproducing by cyclical parthenogenesis and others by permanent parthenogenesis. While the role of facultative symbionts has been well studied during the parthenogenetic phase of their aphid hosts, very little is known on their possible influence during the sexual phase. Here we investigated whether facultative symbionts modulate the capacity to produce sexual forms in various genetic backgrounds of the pea aphid with controlled symbiont composition and also in different aphid genotypes from natural populations with previously characterized infection status and reproductive mode. We found that most facultative symbionts exhibited detrimental effects on their hosts fitness under sex-inducing conditions in comparison with the reference lines. We also showed that the loss of sexual phase in permanently parthenogenetic lineages of A. pisum was not explained by facultative symbionts. Finally, we demonstrated that Spiroplasma infection annihilated the production of males in the host progeny by inducing a male-killing phenotype, an unexpected result for organisms such as aphids that reproduce primarily through clonal reproduction
Racial differences in systemic sclerosis disease presentation: a European Scleroderma Trials and Research group study
Objectives. Racial factors play a significant role in SSc. We evaluated differences in SSc presentations between white patients (WP), Asian patients (AP) and black patients (BP) and analysed the effects of geographical locations.Methods. SSc characteristics of patients from the EUSTAR cohort were cross-sectionally compared across racial groups using survival and multiple logistic regression analyses.Results. The study included 9162 WP, 341 AP and 181 BP. AP developed the first non-RP feature faster than WP but slower than BP. AP were less frequently anti-centromere (ACA; odds ratio (OR) = 0.4, P < 0.001) and more frequently anti-topoisomerase-I autoantibodies (ATA) positive (OR = 1.2, P = 0.068), while BP were less likely to be ACA and ATA positive than were WP [OR(ACA) = 0.3, P < 0.001; OR(ATA) = 0.5, P = 0.020]. AP had less often (OR = 0.7, P = 0.06) and BP more often (OR = 2.7, P < 0.001) diffuse skin involvement than had WP.AP and BP were more likely to have pulmonary hypertension [OR(AP) = 2.6, P < 0.001; OR(BP) = 2.7, P = 0.03 vs WP] and a reduced forced vital capacity [OR(AP) = 2.5, P < 0.001; OR(BP) = 2.4, P < 0.004] than were WP. AP more often had an impaired diffusing capacity of the lung than had BP and WP [OR(AP vs BP) = 1.9, P = 0.038; OR(AP vs WP) = 2.4, P < 0.001]. After RP onset, AP and BP had a higher hazard to die than had WP [hazard ratio (HR) (AP) = 1.6, P = 0.011; HR(BP) = 2.1, P < 0.001].Conclusion. Compared with WP, and mostly independent of geographical location, AP have a faster and earlier disease onset with high prevalences of ATA, pulmonary hypertension and forced vital capacity impairment and higher mortality. BP had the fastest disease onset, a high prevalence of diffuse skin involvement and nominally the highest mortality
Ancient pigs reveal a near-complete genomic turnover following their introduction to Europe
Archaeological evidence indicates that pig domestication had begun by ~10,500 y before the present (BP) in the Near East, and mitochondrial DNA (mtDNA) suggests that pigs arrived in Europe alongside farmers ~8,500 y BP. A few thousand years after the introduction of Near Eastern pigs into Europe, however, their characteristic mtDNA signature disappeared and was replaced by haplotypes associated with European wild boars. This turnover could be accounted for by substantial gene flow from local Euro-pean wild boars, although it is also possible that European wild boars were domesticated independently without any genetic con-tribution from the Near East. To test these hypotheses, we obtained mtDNA sequences from 2,099 modern and ancient pig samples and 63 nuclear ancient genomes from Near Eastern and European pigs. Our analyses revealed that European domestic pigs dating from 7,100 to 6,000 y BP possessed both Near Eastern and European nuclear ancestry, while later pigs possessed no more than 4% Near Eastern ancestry, indicating that gene flow from European wild boars resulted in a near-complete disappearance of Near East ancestry. In addition, we demonstrate that a variant at a locus encoding black coat color likely originated in the Near East and persisted in European pigs. Altogether, our results indicate that while pigs were not independently domesticated in Europe, the vast majority of human-mediated selection over the past 5,000 y focused on the genomic fraction derived from the European wild boars, and not on the fraction that was selected by early Neolithic farmers over the first 2,500 y of the domestication process
Socializing One Health: an innovative strategy to investigate social and behavioral risks of emerging viral threats
In an effort to strengthen global capacity to prevent, detect, and control infectious diseases in animals and people, the United States Agency for International Developmentâs (USAID) Emerging Pandemic Threats (EPT) PREDICT project funded development of regional, national, and local One Health capacities for early disease detection, rapid response, disease control, and risk reduction. From the outset, the EPT approach was inclusive of social science research methods designed to understand the contexts and behaviors of communities living and working at human-animal-environment interfaces considered high-risk for virus emergence. Using qualitative and quantitative approaches, PREDICT behavioral research aimed to identify and assess a range of socio-cultural behaviors that could be influential in zoonotic disease emergence, amplification, and transmission. This broad approach to behavioral risk characterization enabled us to identify and characterize human activities that could be linked to the transmission dynamics of new and emerging viruses. This paper provides a discussion of implementation of a social science approach within a zoonotic surveillance framework. We conducted in-depth ethnographic interviews and focus groups to better understand the individual- and community-level knowledge, attitudes, and practices that potentially put participants at risk for zoonotic disease transmission from the animals they live and work with, across 6 interface domains. When we asked highly-exposed individuals (ie. bushmeat hunters, wildlife or guano farmers) about the risk they perceived in their occupational activities, most did not perceive it to be risky, whether because it was normalized by years (or generations) of doing such an activity, or due to lack of information about potential risks. Integrating the social sciences allows investigations of the specific human activities that are hypothesized to drive disease emergence, amplification, and transmission, in order to better substantiate behavioral disease drivers, along with the social dimensions of infection and transmission dynamics. Understanding these dynamics is critical to achieving health security--the protection from threats to health-- which requires investments in both collective and individual health security. Involving behavioral sciences into zoonotic disease surveillance allowed us to push toward fuller community integration and engagement and toward dialogue and implementation of recommendations for disease prevention and improved health security
Vers un nouveau mode dâaction de peptides antimicrobiens structurĂ©s en feuillets Ă : formation de domaines membranaires par la cateslytine
Le peptide antimicrobien Cateslytine (bCGA RSMRLSFRARGYGFR ) inhibe la libĂ©ration des catĂ©cholamines des cellules chromaffines. Des Ă©tudes biologiques ont montrĂ© que ce peptide est capable dâinhiber aussi la croissance de nombreux microorganismes notamment des bactĂ©ries, des levures ainsi que le parasite Plasmodium falciparum responsable de la malaria. Cependant, le mode dâaction molĂ©culaire demeurait inconnu. Afin de mieux comprendre le ciblage et la sĂ©lectivitĂ© de ce peptide sur les membranes de mammifĂšres ou de microorganismes, nous avons donc envisagĂ© la reconstitution du systĂšme biologique composĂ© initialement de peptides en contact avec des cellules, en le substituant par des modĂšles de membrane, de composition mimant celle des diffĂ©rents microorganismes. Des Ă©tudes structurales ont Ă©tĂ© menĂ©es en utilisant la technique dâATR-FTIR polarisĂ©, le dichroĂŻsme circulaire et la RMN Ă haute rĂ©solution. La dynamique membranaire a Ă©tĂ© Ă©tudiĂ©e en utilisant la RMN des solides du phosphore et du deutĂ©rium. Des expĂ©riences de patch-clamp ont Ă©tĂ© effectuĂ©es afin de mesurer des flux dâions au travers de la membrane. Enfin, de la simulation par ordinateur a permis de comprendre cette interaction au niveau molĂ©culaire. Trois rĂ©sultats principaux sont ressortis de cette approche pluridisciplinaire : i) Des flux ioniques au travers de la membrane attestent de la prĂ©sence de cannaux. ii) La formation de domaines membranaires rigides constituĂ©s de lipides chargĂ©s nĂ©gativement est dĂ©montrĂ©e. iii) Une structuration des peptides en feuillets Ă antiparallĂšles est observĂ©e sur des membranes chargĂ©es nĂ©gativement mimant les microorganismes. Lâensemble de ces rĂ©sultats conduit Ă la proposition dâun mode dâaction dans lequel la dĂ©stabilisation membranaire est induite par les domaines rigides stabilisĂ©s par les agrĂ©gats de peptides structurĂ©s en feuillets Ă.The antimicrobial peptide Cateslytin (bCGA RSMRLSFRARGYGFR ) is a five positively charged arginin rich peptide known to inhibit the release of catecholamine in chromaffin granules. Although biological data showed that it is able to inhibit the growth of several microorganisms such as bacteria, yeast and Plasmodium falciparum parasite involved in malaria, the mechanism of action has not been yet studied. In order to better understand both targeting and selectivity of this peptide towards microorganisms, model membranes of variable compositions have been chosen to respectively mimic microorganisms or mammalian membranes. Structural studies have been performed using polarised ATR-FTIR, circular dichroĂŻsm and high resolution NMR Membrane dynamics has been followed using deuterium labelled lipids and solid state NMR Patch clamp experiments were also performed on lipid vesicles to measure channe conductivity. All-atom molecular dynamics on hydrated peptide-lipid membrane systems was also used to assess the interaction from the atomic level. Main results from this interdisciplinary approach are three-fold. i) Electric current passages through membranes demonstrate permeation akin to pore formation. ii) Peptide-induced formation of rigid domains mainly made of negatively charged lipids is found. iii) Peptide antiparallel Ă-sheets are observed preferentially with negatively charged lipids mimicking microorganism membranes. The general picture leads to the proposal that membrane destabilization/permeation is promoted by rigid domains stabilised by peptide Ă-sheets
Vers un nouveau mode dâaction de peptides antimicrobiens structurĂ©s en feuillets Ă : formation de domaines membranaires par la cateslytine
Le peptide antimicrobien Cateslytine (bCGA RSMRLSFRARGYGFR ) inhibe la libĂ©ration des catĂ©cholamines des cellules chromaffines. Des Ă©tudes biologiques ont montrĂ© que ce peptide est capable dâinhiber aussi la croissance de nombreux microorganismes notamment des bactĂ©ries, des levures ainsi que le parasite Plasmodium falciparum responsable de la malaria. Cependant, le mode dâaction molĂ©culaire demeurait inconnu. Afin de mieux comprendre le ciblage et la sĂ©lectivitĂ© de ce peptide sur les membranes de mammifĂšres ou de microorganismes, nous avons donc envisagĂ© la reconstitution du systĂšme biologique composĂ© initialement de peptides en contact avec des cellules, en le substituant par des modĂšles de membrane, de composition mimant celle des diffĂ©rents microorganismes. Des Ă©tudes structurales ont Ă©tĂ© menĂ©es en utilisant la technique dâATR-FTIR polarisĂ©, le dichroĂŻsme circulaire et la RMN Ă haute rĂ©solution. La dynamique membranaire a Ă©tĂ© Ă©tudiĂ©e en utilisant la RMN des solides du phosphore et du deutĂ©rium. Des expĂ©riences de patch-clamp ont Ă©tĂ© effectuĂ©es afin de mesurer des flux dâions au travers de la membrane. Enfin, de la simulation par ordinateur a permis de comprendre cette interaction au niveau molĂ©culaire. Trois rĂ©sultats principaux sont ressortis de cette approche pluridisciplinaire : i) Des flux ioniques au travers de la membrane attestent de la prĂ©sence de cannaux. ii) La formation de domaines membranaires rigides constituĂ©s de lipides chargĂ©s nĂ©gativement est dĂ©montrĂ©e. iii) Une structuration des peptides en feuillets Ă antiparallĂšles est observĂ©e sur des membranes chargĂ©es nĂ©gativement mimant les microorganismes. Lâensemble de ces rĂ©sultats conduit Ă la proposition dâun mode dâaction dans lequel la dĂ©stabilisation membranaire est induite par les domaines rigides stabilisĂ©s par les agrĂ©gats de peptides structurĂ©s en feuillets Ă.The antimicrobial peptide Cateslytin (bCGA RSMRLSFRARGYGFR ) is a five positively charged arginin rich peptide known to inhibit the release of catecholamine in chromaffin granules. Although biological data showed that it is able to inhibit the growth of several microorganisms such as bacteria, yeast and Plasmodium falciparum parasite involved in malaria, the mechanism of action has not been yet studied. In order to better understand both targeting and selectivity of this peptide towards microorganisms, model membranes of variable compositions have been chosen to respectively mimic microorganisms or mammalian membranes. Structural studies have been performed using polarised ATR-FTIR, circular dichroĂŻsm and high resolution NMR Membrane dynamics has been followed using deuterium labelled lipids and solid state NMR Patch clamp experiments were also performed on lipid vesicles to measure channe conductivity. All-atom molecular dynamics on hydrated peptide-lipid membrane systems was also used to assess the interaction from the atomic level. Main results from this interdisciplinary approach are three-fold. i) Electric current passages through membranes demonstrate permeation akin to pore formation. ii) Peptide-induced formation of rigid domains mainly made of negatively charged lipids is found. iii) Peptide antiparallel Ă-sheets are observed preferentially with negatively charged lipids mimicking microorganism membranes. The general picture leads to the proposal that membrane destabilization/permeation is promoted by rigid domains stabilised by peptide Ă-sheets
Vers un nouveau mode dâaction de peptides antimicrobiens structurĂ©s en feuillets ÎČ : formation de domaines membranaires par la cateslytine
Le peptide antimicrobien Cateslytine (bCGA RSMRLSFRARGYGFR ) inhibe la libĂ©ration des catĂ©cholamines des cellules chromaffines. Des Ă©tudes biologiques ont montrĂ© que ce peptide est capable dâinhiber aussi la croissance de nombreux microorganismes notamment des bactĂ©ries, des levures ainsi que le parasite Plasmodium falciparum responsable de la malaria. Cependant, le mode dâaction molĂ©culaire demeurait inconnu. Afin de mieux comprendre le ciblage et la sĂ©lectivitĂ© de ce peptide sur les membranes de mammifĂšres ou de microorganismes, nous avons donc envisagĂ© la reconstitution du systĂšme biologique composĂ© initialement de peptides en contact avec des cellules, en le substituant par des modĂšles de membrane, de composition mimant celle des diffĂ©rents microorganismes. Des Ă©tudes structurales ont Ă©tĂ© menĂ©es en utilisant la technique dâATR-FTIR polarisĂ©, le dichroĂŻsme circulaire et la RMN Ă haute rĂ©solution. La dynamique membranaire a Ă©tĂ© Ă©tudiĂ©e en utilisant la RMN des solides du phosphore et du deutĂ©rium. Des expĂ©riences de patch-clamp ont Ă©tĂ© effectuĂ©es afin de mesurer des flux dâions au travers de la membrane. Enfin, de la simulation par ordinateur a permis de comprendre cette interaction au niveau molĂ©culaire. Trois rĂ©sultats principaux sont ressortis de cette approche pluridisciplinaire : i) Des flux ioniques au travers de la membrane attestent de la prĂ©sence de cannaux. ii) La formation de domaines membranaires rigides constituĂ©s de lipides chargĂ©s nĂ©gativement est dĂ©montrĂ©e. iii) Une structuration des peptides en feuillets ÎČ antiparallĂšles est observĂ©e sur des membranes chargĂ©es nĂ©gativement mimant les microorganismes. Lâensemble de ces rĂ©sultats conduit Ă la proposition dâun mode dâaction dans lequel la dĂ©stabilisation membranaire est induite par les domaines rigides stabilisĂ©s par les agrĂ©gats de peptides structurĂ©s en feuillets ÎČ.The antimicrobial peptide Cateslytin (bCGA RSMRLSFRARGYGFR ) is a five positively charged arginin rich peptide known to inhibit the release of catecholamine in chromaffin granules. Although biological data showed that it is able to inhibit the growth of several microorganisms such as bacteria, yeast and Plasmodium falciparum parasite involved in malaria, the mechanism of action has not been yet studied. In order to better understand both targeting and selectivity of this peptide towards microorganisms, model membranes of variable compositions have been chosen to respectively mimic microorganisms or mammalian membranes. Structural studies have been performed using polarised ATR-FTIR, circular dichroĂŻsm and high resolution NMR Membrane dynamics has been followed using deuterium labelled lipids and solid state NMR Patch clamp experiments were also performed on lipid vesicles to measure channe conductivity. All-atom molecular dynamics on hydrated peptide-lipid membrane systems was also used to assess the interaction from the atomic level. Main results from this interdisciplinary approach are three-fold. i) Electric current passages through membranes demonstrate permeation akin to pore formation. ii) Peptide-induced formation of rigid domains mainly made of negatively charged lipids is found. iii) Peptide antiparallel ÎČ-sheets are observed preferentially with negatively charged lipids mimicking microorganism membranes. The general picture leads to the proposal that membrane destabilization/permeation is promoted by rigid domains stabilised by peptide ÎČ-sheets
Selectivity of cateslytin for fungi: the role of acidic lipid-ergosterol membrane fluidity in antimicrobial action
International audienc
Molecular analyses of groundwater amphipods (Crustacea: Niphargidae) from Luxembourg: new species reveal limitations of morphology-based checklists
Niphargus amphipods were collected from 2007 to 2018 at 98 sites comprising artificial caverns, springs and interstitial waters in the Grand Duchy of Luxembourg. Opportunistic sampling was combined with passive trapping. Specimen identification was achieved using morphological keys and molecular data. Initial morphological determination and literature data suggested five species, whereas sequencing of fragments of the mitochondrial cytochrome c oxidase subunit 1 gene and nuclear 28S rDNA marker supported the presence of seven species: Niphargus schellenbergi, Niphargus puteanus, Niphargus fontanus, one species of the Niphargus kochianus complex, and three species of the Niphargus aquilex complex. Niphargus schellenbergi was by far the most abundant and widespread species. Limited overlap was observed between literature-based records, our initial morphological determinations based on classical taxonomic characters, and genetic sequence data. In general, the combination of phenotypically variable taxa, such as N. schellenbergi, and cryptic or near-cryptic species, as in the N. aquilex complex, renders morphological identification of niphargids from Luxembourg a challenging or even impossible task. DNA taxonomy will therefore have to be used in future studies of the fauna of this region. info:eu-repo/semantics/publishe
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