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| 2. |
- Barrat, Jean-Louis, et al.
(författare)
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Soft matter roadmap
- 2024
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Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 2515-7639. ; 7:1
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Forskningsöversikt (refereegranskat)abstract
- Soft materials are usually defined as materials made of mesoscopic entities, often self-organised, sensitive to thermal fluctuations and to weak perturbations. Archetypal examples are colloids, polymers, amphiphiles, liquid crystals, foams. The importance of soft materials in everyday commodity products, as well as in technological applications, is enormous, and controlling or improving their properties is the focus of many efforts. From a fundamental perspective, the possibility of manipulating soft material properties, by tuning interactions between constituents and by applying external perturbations, gives rise to an almost unlimited variety in physical properties. Together with the relative ease to observe and characterise them, this renders soft matter systems powerful model systems to investigate statistical physics phenomena, many of them relevant as well to hard condensed matter systems. Understanding the emerging properties from mesoscale constituents still poses enormous challenges, which have stimulated a wealth of new experimental approaches, including the synthesis of new systems with, e.g. tailored self-assembling properties, or novel experimental techniques in imaging, scattering or rheology. Theoretical and numerical methods, and coarse-grained models, have become central to predict physical properties of soft materials, while computational approaches that also use machine learning tools are playing a progressively major role in many investigations. This Roadmap intends to give a broad overview of recent and possible future activities in the field of soft materials, with experts covering various developments and challenges in material synthesis and characterisation, instrumental, simulation and theoretical methods as well as general concepts.
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| 3. |
- Marzal, Alfonso, et al.
(författare)
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Diversity, Loss, and Gain of Malaria Parasites in a Globally Invasive Bird.
- 2011
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:7
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Tidskriftsartikel (refereegranskat)abstract
- Invasive species can displace natives, and thus identifying the traits that make aliens successful is crucial for predicting and preventing biodiversity loss. Pathogens may play an important role in the invasive process, facilitating colonization of their hosts in new continents and islands. According to the Novel Weapon Hypothesis, colonizers may out-compete local native species by bringing with them novel pathogens to which native species are not adapted. In contrast, the Enemy Release Hypothesis suggests that flourishing colonizers are successful because they have left their pathogens behind. To assess the role of avian malaria and related haemosporidian parasites in the global spread of a common invasive bird, we examined the prevalence and genetic diversity of haemosporidian parasites (order Haemosporida, genera Plasmodium and Haemoproteus) infecting house sparrows (Passer domesticus). We sampled house sparrows (N = 1820) from 58 locations on 6 continents. All the samples were tested using PCR-based methods; blood films from the PCR-positive birds were examined microscopically to identify parasite species. The results show that haemosporidian parasites in the house sparrows' native range are replaced by species from local host-generalist parasite fauna in the alien environments of North and South America. Furthermore, sparrows in colonized regions displayed a lower diversity and prevalence of parasite infections. Because the house sparrow lost its native parasites when colonizing the American continents, the release from these natural enemies may have facilitated its invasion in the last two centuries. Our findings therefore reject the Novel Weapon Hypothesis and are concordant with the Enemy Release Hypothesis.
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| 4. |
- Schrey, A W, et al.
(författare)
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Broad-scale latitudinal patterns of genetic diversity among native European and introduced house sparrow (Passer domesticus) populations.
- 2011
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Ingår i: Molecular Ecology. - 0962-1083. ; 20, s. 1133-1143
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Tidskriftsartikel (refereegranskat)abstract
- Introduced species offer unique opportunities to study evolution in new environments, and some provide opportunities for understanding the mechanisms underlying macroecological patterns. We sought to determine how introduction history impacted genetic diversity and differentiation of the house sparrow (Passer domesticus), one of the most broadly distributed bird species. We screened eight microsatellite loci in 316 individuals from 16 locations in the native and introduced ranges. Significant population structure occurred between native than introduced house sparrows. Introduced house sparrows were distinguished into one North American group and a highly differentiated Kenyan group. Genetic differentiation estimates identified a high magnitude of differentiation between Kenya and all other populations, but demonstrated that European and North American samples were differentiated too. Our results support previous claims that introduced North American populations likely had few source populations, and indicate house sparrows established populations after introduction. Genetic diversity also differed among native, introduced North American, and Kenyan populations with Kenyan birds being least diverse. In some cases, house sparrow populations appeared to maintain or recover genetic diversity relatively rapidly after range expansion (<50 years; Mexico and Panama), but in others (Kenya) the effect of introduction persisted over the same period. In both native and introduced populations, genetic diversity exhibited large-scale geographic patterns, increasing towards the equator. Such patterns of genetic diversity are concordant with two previously described models of genetic diversity, the latitudinal model and the species diversity model.
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| 5. |
- Teplitsky, Celine, et al.
(författare)
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Assessing Multivariate Constraints to Evolution across Ten Long-Term Avian Studies
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3, s. e90444-
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Tidskriftsartikel (refereegranskat)abstract
- Background: In a rapidly changing world, it is of fundamental importance to understand processes constraining or facilitating adaptation through microevolution. As different traits of an organism covary, genetic correlations are expected to affect evolutionary trajectories. However, only limited empirical data are available. Methodology/Principal Findings: We investigate the extent to which multivariate constraints affect the rate of adaptation, focusing on four morphological traits often shown to harbour large amounts of genetic variance and considered to be subject to limited evolutionary constraints. Our data set includes unique long-term data for seven bird species and a total of 10 populations. We estimate population-specific matrices of genetic correlations and multivariate selection coefficients to predict evolutionary responses to selection. Using Bayesian methods that facilitate the propagation of errors in estimates, we compare (1) the rate of adaptation based on predicted response to selection when including genetic correlations with predictions from models where these genetic correlations were set to zero and (2) the multivariate evolvability in the direction of current selection to the average evolvability in random directions of the phenotypic space. We show that genetic correlations on average decrease the predicted rate of adaptation by 28%. Multivariate evolvability in the direction of current selection was systematically lower than average evolvability in random directions of space. These significant reductions in the rate of adaptation and reduced evolvability were due to a general nonalignment of selection and genetic variance, notably orthogonality of directional selection with the size axis along which most (60%) of the genetic variance is found. Conclusions: These results suggest that genetic correlations can impose significant constraints on the evolution of avian morphology in wild populations. This could have important impacts on evolutionary dynamics and hence population persistence in the face of rapid environmental change.
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| 6. |
- Herrero del Valle, Alba, et al.
(författare)
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Ornithine capture by a translating ribosome controls bacterial polyamine synthesis
- 2020
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Ingår i: Nature Microbiology. - : Springer Nature. - 2058-5276. ; 5:4, s. 554-561
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Tidskriftsartikel (refereegranskat)abstract
- A combination of cellular, molecular and structural biology approaches explains how the translating ribosome and the nascent peptide SpeFL interact to form a binding pocket that serves as an ornithine sensor to regulate polyamine biosynthesis in pathogenic bacteria. Polyamines are essential metabolites that play an important role in cell growth, stress adaptation and microbial virulence(1-3). To survive and multiply within a human host, pathogenic bacteria adjust the expression and activity of polyamine biosynthetic enzymes in response to different environmental stresses and metabolic cues(2). Here, we show that ornithine capture by the ribosome and the nascent peptide SpeFL controls polyamine synthesis in gamma-proteobacteria by inducing the expression of the ornithine decarboxylase SpeF(4), via a mechanism involving ribosome stalling and transcription antitermination. In addition, we present the cryogenic electron microscopy structure of an Escherichia coli ribosome stalled during translation of speFL in the presence of ornithine. The structure shows how the ribosome and the SpeFL sensor domain form a highly selective binding pocket that accommodates a single ornithine molecule but excludes near-cognate ligands. Ornithine pre-associates with the ribosome and is then held in place by the sensor domain, leading to the compaction of the SpeFL effector domain and blocking the action of release factor 1. Thus, our study not only reveals basic strategies by which nascent peptides assist the ribosome in detecting a specific metabolite, but also provides a framework for assessing how ornithine promotes virulence in several human pathogens.
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| 7. |
- Magallanes, S., et al.
(författare)
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El volumen de la glándula uropigial y la infección por malaria varía entre hábitats urbano-rural en el gorrión común
- 2020
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Ingår i: Ecosistemas. - 1697-2473. ; 29:2
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Tidskriftsartikel (refereegranskat)abstract
- All the organisms have developed defensive against different (parasites, harsh environmental conditions or contaminants) to which they should face in their environments. To deal with these selective factors, birds have developed defensive mechanisms such as the uropygial gland, which produces a secretion acting as a physico-chemical defensive barrier against a high diversity of ectoparasites and prevent the potential transmission of blood parasites. Therefore, this secretion plays a fundamental role on the feather resistance to abrasion. However, there is still little knowledge about the functional adaptations of this gland to different environments. Here, we analysed the variation in uropygial gland volume in relation to different habitats (rural vs. urban) and to malaria infection in house sparrows (Passer domesticus). Our results showed that rural sparrows infected with malaria had the lowest uropygial volume. Furthermore, we found a positive relationship between uropygial gland volume and body condition, regardless of habitat, sex or prevalence of infection (infected or uninfected). These findings highlight the important role of this gland in the avian body condition and on its adaptation to different environments.
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| 8. |
- Marzal, A, et al.
(författare)
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Effects of malaria double infection in birds: one plus one is not two.
- 2008
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Ingår i: Journal of evolutionary biology. - : Wiley. - 1420-9101 .- 1010-061X. ; 21:4, s. 979-987
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Tidskriftsartikel (refereegranskat)abstract
- Avian malaria parasites are supposed to exert negative effects on host fitness because these intracellular parasites affect host metabolism. Recent advances in molecular genotyping and microscopy have revealed that coinfections with multiple parasites are frequent in bird-malaria parasite systems. However, studies of the fitness consequences of such double infections are scarce and inconclusive. We tested if the infection with two malaria parasite lineages has more negative effects than single infection using 6 years of data from a natural population of house martins. Survival was negatively affected by both types of infections. We found an additive cost from single to double infection in body condition, but not in reproductive parameters (double-infected had higher reproductive success). These results demonstrate that malaria infections decrease survival, but also have different consequences on the breeding performance of single- and double-infected wild birds.
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