33 research outputs found
Going Coastal: Shared Evolutionary History between Coastal British Columbia and Southeast Alaska Wolves (Canis lupus)
Many coastal species occupying the temperate rainforests of the Pacific Northwest in North America comprise endemic populations genetically and ecologically distinct from interior continental conspecifics. Morphological variation previously identified among wolf populations resulted in recognition of multiple subspecies of wolves in the Pacific Northwest. Recently, separate genetic studies have identified diverged populations of wolves in coastal British Columbia and coastal Southeast Alaska, providing support for hypotheses of distinct coastal subspecies. These two regions are geographically and ecologically contiguous, however, there is no comprehensive analysis across all wolf populations in this coastal rainforest.By combining mitochondrial DNA datasets from throughout the Pacific Northwest, we examined the genetic relationship between coastal British Columbia and Southeast Alaska wolf populations and compared them with adjacent continental populations. Phylogenetic analysis indicates complete overlap in the genetic diversity of coastal British Columbia and Southeast Alaska wolves, but these populations are distinct from interior continental wolves. Analyses of molecular variation support the separation of all coastal wolves in a group divergent from continental populations, as predicted based on hypothesized subspecies designations. Two novel haplotypes also were uncovered in a newly assayed continental population of interior Alaska wolves.We found evidence that coastal wolves endemic to these temperate rainforests are diverged from neighbouring, interior continental wolves; a finding that necessitates new international strategies associated with the management of this species
The Mutyh Base Excision Repair Gene Influences the Inflammatory Response in a Mouse Model of Ulcerative Colitis
BACKGROUND: The Mutyh DNA glycosylase is involved in the repair of oxidized DNA bases. Mutations in the human MUTYH gene are responsible for colorectal cancer in familial adenomatous polyposis. Since defective DNA repair genes might contribute to the increased cancer risk associated with inflammatory bowel diseases, we compared the inflammatory response of wild-type and Mutyh(-/-) mice to oxidative stress. METHODOLOGY/PRINCIPAL FINDINGS: The severity of colitis, changes in expression of genes involved in DNA repair and inflammation, DNA 8-oxoguanine levels and microsatellite instability were analysed in colon of mice treated with dextran sulfate sodium (DSS). The Mutyh(-/-) phenotype was associated with a significant accumulation of 8-oxoguanine in colon DNA of treated mice. A single DSS cycle induced severe acute ulcerative colitis in wild-type mice, whereas lesions were modest in Mutyh(-/-) mice, and this was associated with moderate variations in the expression of several cytokines. Eight DSS cycles caused chronic colitis in both wild-type and Mutyh(-/-) mice. Lymphoid hyperplasia and a significant reduction in Foxp3(+) regulatory T cells were observed only in Mutyh(-/-) mice. CONCLUSIONS: The findings indicate that, in this model of ulcerative colitis, Mutyh plays a major role in maintaining intestinal integrity by affecting the inflammatory response
Analytical methods for structural ensembles and dynamics of intrinsically disordered proteins
Influence de l’équilibre de protonation de la polyaniline sur la réaction d’échange de l’ion ferrocyanure
Nous avons étudié par impédances ac et EHD la réaction d’oxydation de [Fe(CN)6]4- sur des électrodes modifiées par la polyaniline. Nous avons observé un phénomène de relaxation autour de pH = 3 qui correspond d’après les données de la littérature au pK de la forme imine de l’éméraldine. Ce phénomène a été étudié en fonction de plusieurs paramètres expérimentaux tels que le potentiel, le pH, la vitesse de rotation de l’électrode, et la concentration du substrat redox. Nous avons ensuite comparé les résultats expérimentaux avec un modèle cinétique développé pour un polymère redox en prenant en compte l’équilibre de protonation de la polyaniline
Impédance électrochimique de membranes de polyaniline
L'impédance d'une membrane de polymère conducteur a été calculée en décrivant le transport des radicaux cation du polymère et des contre-ions par une équation de Nernst-Planck. On applique ce modèle d'impédance à une membrane de polyaniline placée dans différents milieux acides et on en déduit les coefficients de diffusion des différents anions et des radicaux cations
Étude du transport ionique dans le polyéthylcarbazole par microbalance à quartz et par effet mirage
On a comparé pour le polyéthylcarbazole en milieu acide perchlorique 5M, la réponse de la microbalance à quartz et celle de l'effet mirage en régime dynamique.Dans la phase de réduction, seule la sortie des ions perchlorate intervient alors que dans la phase d'oxydation il y a simultanément sortie de protons et entrée d'anions. Par impédance massique en régime quasi-stationnaire on montre que seuls les anions interviennent. Ces résultats sont expliqués par les différences de conduction ionique du film entre les états oxydés ou réduits