58 research outputs found
Non-normalizable quasi-equilibrium states under fractional dynamics
We study non-normalizable quasi-equilibrium states (NNQE) arising from
anomalous diffusion. Initially, particles in contact with a thermal bath are
released from an asymptotically flat potential well, with dynamics that is
described by fractional calculus. For temperatures that are sufficiently low
compared to the potential depth, the properties of the system remain almost
constant in time. We use the fractional-time Fokker-Planck equation (FTFPE) and
continuous-time random walk approaches to calculate the ensemble averages of
observables. We obtain analytical estimates of the duration of NNQE, depending
on the fractional order, from approximate theoretical solutions of the FTFPE.
We study and compare two types of observables, the mean square displacement
typically used to characterize diffusion, and the thermodynamic energy. We show
that the typical time scales for stagnation depend exponentially on the
activation energy in units of temperature multiplied by a function of the
fractional exponent.Comment: 9 pages, 6 figure
Effects of Inhaled Nitric Oxide on Oxidative Stress and Histopathological and Inflammatory Lung Injury in a Saline-Lavaged Rabbit Model of Acute Lung Injury
Age‐related changes in the biophysical and morphological characteristics of mouse cochlear outer hair cells
Outer hair cells (OHCs) are electromotile sensory receptors that provide sound amplification within the mammalian cochlea. Although OHCs appear susceptible to ageing, the progression of the pathophysiological changes in these cells is still poorly understood. By using mouse strains with a different progression of hearing loss (C57BL/6J, C57BL/6NTac, C57BL/6NTacCdh23+ , C3H/HeJ), we have identified morphological, physiological and molecular changes in ageing OHCs (9–12 kHz cochlear region). We show that by 6 months of age, OHCs from all strains underwent a reduction in surface area, which was not a sign of degeneration. Although the ageing OHCs retained a normal basolateral membrane protein profile, they showed a reduction in the size of the K+ current and non‐linear capacitance, a readout of prestin‐dependent electromotility. Despite these changes, OHCs have a normal V m and retain the ability to amplify sound, as distortion product otoacoustic emission thresholds were not affected in aged, good‐hearing mice (C3H/HeJ, C57BL/6NTacCdh23+ ). The loss of afferent synapses was present in all strains at 15 months. The number of efferent synapses per OHCs, defined as postsynaptic SK2 puncta, was reduced in aged OHCs of all strains apart from C3H mice. Several of the identified changes occurred in aged OHCs from all mouse strains, thus representing a general trait in the pathophysiological progression of age‐related hearing loss, possibly aimed at preserving functionality. We have also shown that the mechanoelectrical transduction (MET) current from OHCs of mice harbouring the Cdh23ahl allele is reduced with age, highlighting the possibility that changes in the MET apparatus could play a role in cochlear ageing
Reconciling the biogeography of an invader through recent and historic genetic patterns: the case of topmouth gudgeon Pseudorasbora parva
© 2018 The Author(s) The genetic variability and population structure of introduced species in their native range are potentially important determinants of their invasion success, yet data on native populations are often poorly represented in relevant studies. Consequently, to determine the contribution of genetic structuring in the native range of topmouth gudgeon Pseudorasbora parva to their high invasion success in Europe, we used a dataset comprising of 19 native and 11 non-native populations. A total of 666 samples were analysed at 9 polymorphic microsatellite loci and sequenced for 597 bp of mitochondrial DNA. The analysis revealed three distinct lineages in the native range, of which two haplogroups were prevalent in China (100%), with a general split around the Qinling Mountains. Dating of both haplogroups closely matched past geological events. More recently, its distribution has been influenced by fish movements in aquaculture, resulting in gene flow between previously separated populations in Northern and Southern China. Their phylogeography in Europe indicate as few as two introductions events and two dispersal routes. Microsatellite data revealed native populations had higher genetic diversity than those in the invasive range, a contrast to previous studies on P. parva. This study confirms the importance of extensive sampling in both the native and non-native range of invasive species in evaluating the influence of genetic variability on invasion success
Common garden experiments in the genomic era : new perspectives and opportunities
PdV was supported by a doctoral studentship from the French Ministère de la Recherche et de l’Enseignement Supérieur. OEG was supported by the Marine Alliance for Science and Technology for Scotland (MASTS)The study of local adaptation is rendered difficult by many evolutionary confounding phenomena (e.g. genetic drift and demographic history). When complex traits are involved in local adaptation, phenomena such as phenotypic plasticity further hamper evolutionary biologists to study the complex relationships between phenotype, genotype and environment. In this perspective paper, we suggest that the common garden experiment, specifically designed to deal with phenotypic plasticity has a clear role to play in the study of local adaptation, even (if not specifically) in the genomic era. After a quick review of some high-throughput genotyping protocols relevant in the context of a common garden, we explore how to improve common garden analyses with dense marker panel data and recent statistical methods. We then show how combining approaches from population genomics and genome-wide association studies with the settings of a common garden can yield to a very efficient, thorough and integrative study of local adaptation. Especially, evidence from genomic (e.g. genome scan) and phenotypic origins constitute independent insights into the possibility of local adaptation scenarios, and genome-wide association studies in the context of a common garden experiment allow to decipher the genetic bases of adaptive traits.PostprintPeer reviewe
Where the Lake Meets the Sea: Strong Reproductive Isolation Is Associated with Adaptive Divergence between Lake Resident and Anadromous Three-Spined Sticklebacks
Contact zones between divergent forms of the same species are often characterised by high levels of phenotypic diversity over small geographic distances. What processes are involved in generating such high phenotypic diversity? One possibility is that introgression and recombination between divergent forms in contact zones results in greater phenotypic and genetic polymorphism. Alternatively, strong reproductive isolation between forms may maintain distinct phenotypes, preventing homogenisation by gene flow. Contact zones between divergent freshwater-resident and anadromous stickleback (Gasterosteus aculeatus L.) forms are numerous and common throughout the species distribution, offering an opportunity to examine these contrasting hypotheses in greater detail. This study reports on an interesting new contact zone located in a tidally influenced lake catchment in western Ireland, characterised by high polymorphism for lateral plate phenotypes. Using neutral and QTL-linked microsatellite markers, we tested whether the high diversity observed in this contact zone arose as a result of introgression or reproductive isolation between divergent forms: we found strong support for the latter hypothesis. Three phenotypic and genetic clusters were identified, consistent with two divergent resident forms and a distinct anadromous completely plated population that migrates in and out of the system. Given the strong neutral differentiation detected between all three morphotypes (mean F-ST = 0.12), we hypothesised that divergent selection between forms maintains reproductive isolation. We found a correlation between neutral genetic and adaptive genetic differentiation that support this. While strong associations between QTL linked markers and phenotypes were also observed in this wild population, our results support the suggestion that such associations may be more complex in some Atlantic populations compared to those in the Pacific. These findings provide an important foundation for future work investigating the dynamics of gene flow and adaptive divergence in this newly discovered stickleback contact zone
Avaliação do cetoconazol em camundongos inoculados com Paracoccidioides brasiliensis pela histopatologia de fígado e baço e pela intradermorreação de paracoccidioidina
Low genetic and phenotypic divergence in a contact zone between freshwater and marine sticklebacks: gene flow constrains adaptation
Distinctive insular forms of threespine stickleback (Gasterosteus aculeatus) from western Mediterranean islands
Neutral and adaptive variation among populations within a species is a major component of biological diversity and may be pronounced among insular populations due to geographical isolation and island specific evolutionary forces at work. Detecting and preserving potential evolutionary significant units below the species rank has become a crucial task for conservation biology. Combining genetic, phenotypic and ecological data, we investigated evolutionary patterns among the enigmatic threespine stickleback populations from western Mediterranean islands, all of which are threatened by habitat deterioration and climate change. We find indications that these populations derive from different genetic lineages, being genetically highly distinct from the stickleback of mainland Europe and the northern Atlantic as well as from each other. Mediterranean island stickleback populations are also phenotypically distinct from mainland populations but interestingly stickleback from Iceland have converged on a similar phenotype. This distinctive island stickleback phenotype seems to be driven by distinct selective regimes on islands versus continents. Overall, our results reveal the status of western Mediterranean island stickleback as evolutionarily distinct units, important for conservation of biodiversity
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