160 research outputs found
Effects of predation on the ecology of Arctic-nesting shorebirds
L'hypothĂšse des proies alternatives suggĂšre que la rĂ©ponse fonctionnelle et numĂ©rique des prĂ©dateurs Ă la fluctuation des populations de proies influence le risque de prĂ©dation annuel sur d'autres proies comme les Ćufs d'oiseaux. Dans certains systĂšmes du Haut-Arctique caractĂ©risĂ©s par des populations cycliques de lemmings, le comportement de changement de prĂ©fĂ©rence des prĂ©dateurs a Ă©tĂ© mis en lien avec les fluctuations observĂ©es chez des populations d'oiseaux co-existantes. Le but gĂ©nĂ©ral de cette thĂšse Ă©tait d'Ă©tudier les effets en cascade des interactions prĂ©dateur-proie sur une proie alternative, les Ćufs d'oiseaux de rivage. Les deux principaux objectifs Ă©taient : 1) d'Ă©tudier les effets de l'abondance de proies prĂ©fĂ©rĂ©es (lemmings) et de proies alternatives (oies), sur les tendances temporelles et spatiales du risque de prĂ©dation et de la survie des nids d'oiseaux de rivage, et 2) d'investiguer les tendances spatiales du risque de prĂ©dation Ă grande Ă©chelle dans l'Arctique canadien. Pour atteindre ces objectifs, des donnĂ©es sur le risque de prĂ©dation (mesurĂ© Ă l'aide de nids artificiels) et sur la survie des nids d'oiseaux de rivage (mesurĂ©e avec les nids naturels) ont Ă©tĂ© recueillies sur une pĂ©riode de 5 ans Ă l'Ăźle Bylot (Nunavut). Des donnĂ©es sur l'identitĂ© et l'activitĂ© des prĂ©dateurs (par camĂ©ra) ainsi que l'abondance des prĂ©dateurs (renard arctique) et l'abondance des proies alternatives (lemmings et oies) ont Ă©galement Ă©tĂ© recueillies. Pour caractĂ©riser les tendances Ă grande Ă©chelle spatiale, le risque de prĂ©dation sur des nids artificiels a Ă©tĂ© mesurĂ© Ă 7 sites le long d'un gradient latitudinal de 3350 km dans l'Arctique canadien. Ă l'Ăźle Bylot, les camĂ©ras de surveillance ont rĂ©vĂ©lĂ© que le renard arctique est le principal prĂ©dateur des Ćufs dans les nids artificiels de mĂȘme que dans les vĂ©ritables nids d'oiseaux de rivage. Les donnĂ©es rĂ©coltĂ©es sur une pĂ©riode de 5 ans ont dĂ©montrĂ© un effet nĂ©gatif significatif de l'abondance de lemmings sur le risque de prĂ©dation. Les probabilitĂ©s de survie des nids artificiels Ă©taient quant Ă elles reliĂ©es nĂ©gativement Ă l'abondance de renards mais, positivement Ă l'abondance d'oiseaux prĂ©dateurs. De mĂȘme, le meilleur facteur expliquant les variations interannuelles de la survie journaliĂšre des nids d'oiseaux de rivage Ă©tait l'abondance de lemmings. En effet, la survie des nids fut plus basse dans les annĂ©es de faible abondance de lemmings. Les risques de prĂ©dation des nids d'oiseaux de rivage dans une colonie d'oies Ă©taient positivement reliĂ©s Ă la densitĂ© de nids d'oies. Toutefois cette relation Ă©tait forte et significative seulement l'annĂ©e de faible abondance de lemmings, soit une augmentation de prĂšs de 600% quand la densitĂ© de nids d'oies est passĂ©e de 0 Ă 24 nids par hectare. Puisque nous avons confirmĂ© que le renard arctique est un prĂ©dateur commun des lemmings, des Ćufs d'oies et des Ćufs d'oiseaux de rivage, ces donnĂ©es supportent l'hypothĂšse d'effets en cascade de l'abondance des proies prĂ©fĂ©rĂ©es et alternatives sur le risque de prĂ©dation de proies accidentelles comme les oiseaux de rivage. En ce qui a trait au risque de prĂ©dation Ă plus grande Ă©chelle spatiale, nous avons observĂ© une diminution significative du risque de prĂ©dation avec la latitude, ce qui indique que les oiseaux qui migrent plus vers le nord peuvent bĂ©nĂ©ficier d'avantages en termes de reproduction sous la forme d'une diminution du risque de prĂ©dation des nids. Sur la base de ces rĂ©sultats, le risque de prĂ©dation semble jouer, Ă plusieurs Ă©chelles spatiales, un rĂŽle central dans l'Ă©cologie de la reproduction des oiseaux de rivage nichant dans l'Arctique. Les recherches futures devraient Ă©tudier les mĂ©canismes qui relient les interactions trophiques des proies prĂ©fĂ©rĂ©es, alternatives et accidentelles Ă l'Ă©chelle locale avec les tendances Ă grande Ă©chelle spatiale du risque de prĂ©dation sur les oiseaux nichant dans l'Arctique.\ud
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MOTS-CLĂS DE LâAUTEUR : risque de prĂ©dation, proies alternatives, oiseaux de rivage, oies, lemming
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Presentation for the Tarrant County College Northwest Campus discussing copyright, open educational resources, and creative commons licensing
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Copyright, Open Access, and Library Instruction
Article discussing copyright, open access, and library instruction
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Kv2.1 channels play opposing roles in regulating membrane potential, Ca2+ channel function, and myogenic tone in arterial smooth muscle.
The accepted role of the protein Kv2.1 in arterial smooth muscle cells is to form K+ channels in the sarcolemma. Opening of Kv2.1 channels causes membrane hyperpolarization, which decreases the activity of L-type CaV1.2 channels, lowering intracellular Ca2+ ([Ca2+]i) and causing smooth muscle relaxation. A limitation of this model is that it is based exclusively on data from male arterial myocytes. Here, we used a combination of electrophysiology as well as imaging approaches to investigate the role of Kv2.1 channels in male and female arterial myocytes. We confirmed that Kv2.1 plays a canonical conductive role but found it also has a structural role in arterial myocytes to enhance clustering of CaV1.2 channels. Less than 1% of Kv2.1 channels are conductive and induce membrane hyperpolarization. Paradoxically, by enhancing the structural clustering and probability of CaV1.2-CaV1.2 interactions within these clusters, Kv2.1 increases Ca2+ influx. These functional impacts of Kv2.1 depend on its level of expression, which varies with sex. In female myocytes, where expression of Kv2.1 protein is higher than in male myocytes, Kv2.1 has conductive and structural roles. Female myocytes have larger CaV1.2 clusters, larger [Ca2+]i, and larger myogenic tone than male myocytes. In contrast, in male myocytes, Kv2.1 channels regulate membrane potential but not CaV1.2 channel clustering. We propose a model in which Kv2.1 function varies with sex: in males, Kv2.1 channels control membrane potential but, in female myocytes, Kv2.1 plays dual electrical and CaV1.2 clustering roles. This contributes to sex-specific regulation of excitability, [Ca2+]i, and myogenic tone in arterial myocytes
Copyright, open access and library instruction
Article discussing copyright, open access, and library instruction
A structural comparison of salt forms of dopamine with the structures of other phenylethylamines
The structures of four salt forms of dopamine are reported. These are dopamine [2â(3,4âdihydroxyphenyl)ethanâ1âaminium] benzoate, C8H12NO2+·C7H5O2â, I, dopamine 4ânitrobenzoate, C8H12NO2+·C7H4NO4â, II, dopamine ethanedisulfonate, 2C8H12NO2+·C2H4O6S22â, III, and dopamine 4âhydroxybenzenesulfonate monohydrate, C8H12NO2+·C6H5O4Sâ·H2O, IV. In all four structures, the dopamine cation adopts an extended conformation. Intermolecular interaction motifs that are common in the salt forms of tyramine can be found in related dopamine structures, but hydrogen bonding in the dopamine structures appear to be more variable and less predictable than for tyramine. Packing analysis discovered three dopamineâcontaining groups of structures that can be described as isostructural with regards to the cation positions. Two of these groups contain both dopamine and tyramine species, and one of these is also highly variable in other ways too, containing anhydrous and hydrated forms, different anion types and ionized and neutral phenylethylamine species. As such, the group illustrates that packing behaviour can be robust and similar even where intermolecular interactions such as hydrogen bonds are very different
Potential Circumstances Associated With Moral Injury and Moral Distress in Healthcare Workers and Public Safety Personnel Across the Globe During COVID-19: A Scoping Review
Healthcare workers (HCWs) and public safety personnel (PSP) across the globe have continued to face ethically and morally challenging situations during the COVID-19 pandemic that increase their risk for the development of moral distress (MD) and moral injury (MI). To date, however, the global circumstances that confer risk for MD and MI in these cohorts have not been systematically explored, nor have the unique circumstances that may exist across countries been explored. Here, we sought to identify and compare, across the globe, potentially morally injurious or distressful events (PMIDEs) in HCWs and PSP during the COVID-19 pandemic. A scoping review was conducted to identify and synthesize global knowledge on PMIDEs in HCWs and select PSP. Six databases were searched, including MEDLINE, EMBASE, Web of Science, PsychInfo, CINAHL, and Global Health. A total of 1,412 articles were retrieved, of which 57 articles were included in this review. These articles collectively described the experiences of samples from 19 different countries, which were comprised almost exclusively of HCWs. Given the lack of PSP data, the following results should not be generalized to PSP populations without further research. Using qualitative content analysis, six themes describing circumstances associated with PMIDEs were identified: (1) Risk of contracting or transmitting COVID-19; (2) Inability to work on the frontlines; (3) Provision of suboptimal care; (4) Care prioritization and resource allocation; (5) Perceived lack of support and unfair treatment by their organization; and (6) Stigma, discrimination, and abuse. HCWs described a range of emotions related to these PMIDEs, including anxiety, fear, guilt, shame, burnout, anger, and helplessness. Most PMIDE themes appeared to be shared globally, particularly the âRisk of contracting or transmitting COVID-19â and the âPerceived lack of support and unfair treatment by their organization.â Articles included within the theme of âStigma, discrimination, and abuseâ represented the smallest global distribution of all PMIDE themes. Overall, the present review provides insight into PMIDEs encountered by HCWs across the globe during COVID-19. Further research is required to differentiate the experience of PSP from HCWs, and to explore the impact of social and cultural factors on the experience of MD and MI
Structure-based design, synthesis and biological evaluation of a novel series of isoquinolone and pyrazolo[4,3-c]pyridine inhibitors of fascin 1 as potential anti-metastatic agents
Fascin is an actin binding and bundling protein that is not expressed in normal epithelial tissues but overexpressed in a variety of invasive epithelial tumors. It has a critical role in cancer cell metastasis by promoting cell migration and invasion. Here we report the crystal structures of fascin in complex with a series of novel and potent inhibitors. Structure-based elaboration of these compounds enabled the development of a series with nanomolar affinities for fascin, good physicochemical properties and the ability to inhibit fascin-mediated bundling of filamentous actin. These compounds provide promising starting points for fascin-targeted anti-metastatic therapies
Microbiome Composition and Function Drives Wound-Healing Impairment in the Female Genital Tract
The mechanism(s) by which bacterial communities impact susceptibility to infectious diseases, such as HIV, and maintain female genital tract (FGT) health are poorly understood. Evaluation of FGT bacteria has predominantly been limited to studies of species abundance, but not bacterial function. We therefore sought to examine the relationship of bacterial community composition and function with mucosal epithelial barrier health in the context of bacterial vaginosis (BV) using metaproteomic, metagenomic, and in vitro approaches. We found highly diverse bacterial communities dominated by Gardnerella vaginalis associated with host epithelial barrier disruption and enhanced immune activation, and low diversity communities dominated by Lactobacillus species that associated with lower Nugent scores, reduced pH, and expression of host mucosal proteins important for maintaining epithelial integrity. Importantly, proteomic signatures of disrupted epithelial integrity associated with G. vaginalis-dominated communities in the absence of clinical BV diagnosis. Because traditional clinical assessments did not capture this, it likely represents a larger underrepresented phenomenon in populations with high prevalence of G. vaginalis. We finally demonstrated that soluble products derived from G. vaginalis inhibited wound healing, while those derived from L. iners did not, providing insight into functional mechanisms by which FGT bacterial communities affect epithelial barrier integrity
A cluster randomized controlled platform trial comparing group MEmory specificity training (MEST) to group psychoeducation and supportive counselling (PSC) in the treatment of recurrent depression.
Impaired ability to recall specific autobiographical memories is characteristic of depression, which when reversed, may have therapeutic benefits. This cluster-randomized controlled pilot trial investigated efficacy and aspects of acceptability, and feasibility of MEmory Specificity Training (MEST) relative to Psychoeducation and Supportive Counselling (PSC) for Major Depressive Disorder (NâŻ=âŻ62). A key aim of this study was to determine a range of effect size estimates to inform a later phase trial. Assessments were completed at baseline, post-treatment and 3-month follow-up. The cognitive process outcome was memory specificity. The primary clinical outcome was symptoms on the Beck Depression Inventory-II at 3-month follow-up. The MEST group demonstrated greater improvement in memory specificity relative to PSC at post-intervention (dâŻ=âŻ0.88) and follow-up (dâŻ=âŻ0.74), relative to PSC. Both groups experienced a reduction in depressive symptoms at 3-month follow-up (dâŻ=âŻ0.67). However, there was no support for a greater improvement in depressive symptoms at 3 months following MEST relative to PSC (dâŻ=âŻ-0.04). Although MEST generated changes on memory specificity and improved depressive symptoms, results provide no indication that MEST is superior to PSC in the resolution of self-reported depressive symptoms. Implications for later-phase definitive trials of MEST are discussed
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