Impacts des changements climatiques sur le potentiel de survie de huit espèces de plantes vasculaires en situation précaire au Québec

Le climat global se modifie à une vitesse alarmante. Selon le groupe d'experts intergouvernemental sur l'évolution du climat, la température globale pourrait augmenter de 0,3 °C à 4,8 °C d’ici 2100. Le Québec serait également touché par les changements climatiques. Il est évalué que les écosystèmes propices aux espèces végétales tempérées et boréales pourraient subir une migration de 200 à 1200 kilomètres vers le nord, d’ici 2100. D’autres modifications du climat se feront également ressentir dans les précipitations annuelles, le couvert de neige, les périodes de croissance et les périodes de sécheresse. L’objectif principal de cette production de fin d’études est d’évaluer le potentiel de survie de huit espèces de plantes vasculaires en situation précaire au Québec face aux changements climatiques. Ces espèces sont l’arabette du Québec (Boechera quebecensis), l’aristide à rameaux basilaires (Aristida basiramea), l’arnica de Griscom (Arnica griscomii subsp. griscomii), l’aspidote touffue (Aspidotis densa), la floerkée fausse-proserpinie (Floerkea proserpinacoides), le gaylussaquier de Bigelow (Gaylussacia bigeloviana), la phégoptère à hexagones (Phegopteris hexagonoptera) et le séneçon fausse-cymbalaire (Packera cymbalaria). L’étude de ces espèces et de leurs habitats a permis d’identifier 17 impacts potentiels différents des changements climatiques. Ces impacts concernent principalement l’augmentation de la compétition faite par l’introduction de nouvelles espèces, la perte ou la détérioration de l’habitat, la modification du taux de reproduction et d’autres impacts entravant la survie de ces espèces. Finalement, des recommandations ont été formulées, afin de limiter les impacts des changements climatiques sur ces espèces au Québec. Ces recommandations ciblent des actions concrètes comme la lutte aux espèces envahissantes et la migration assistée. Celles-ci visent également les méthodes de suivi, les méthodes de gestion des populations et la réalisation d’études plus approfondies sur les espèces et les écosystèmes du Québec

Que veut dire avoir un corps et exister ? Martin Heidegger et le « problème du corps » (1959-1976)

Ce mémoire est une étude à la jonction des études germaniques et de la phénoménologie, et s’efforce de reconstituer la problématique de l’interrogation et de la définition de l’homme à partir de l’oeuvre de Martin Heidegger (1889-1976). Prenant une perspective à la fois historiographique et philosophique, l’ambition de cette étude consiste à reconstruire un moment du corpus de Heidegger afin d’en exposer la pertinence et l’actualité philosophiques. Cette étude est divisée en trois chapitres. Le premier chapitre reprend et analyse le « programme onto-phénoménologique » déployé dans Sein und Zeit, afin de comprendre comment l’« homme » était analysé de façon nouvelle par l’auteur. Le second formule l’hypothèse historiographique d’un « Heidegger III » (1959-1976), autrement dit d’un dernier Heidegger, avec l’ambition d’exposer comment la définition de l’« homme » entreprise par Heidegger s’est peu à peu modifiée afin de répondre à des difficultés d’ordre thématique et méthodologique, lesquelles furent rassemblées sous l’intitulé d’un « problème du corps » (Leibproblematik). Cette hypothèse doit en outre expliciter le statut fondamental du « corps » (Leib) dans la dernière période de l’oeuvre de Heidegger, en mettant en lumière l’importance d’un « Nietzsche matriciel » dans la réélaboration d’une interrogation et d’une définition de l’« homme » fondées sur la corporalité (Leiblichkeit). Enfin, le troisième chapitre s’attarde à comprendre et évaluer la portée et les conséquences philosophiques de cette définition heideggérienne de l’homme à partir du « corps » (Leib), notamment dans la distinction de l’homme du reste du vivant et dans la caractérisation de la « culture »

Développement d’une nouvelle méthode de régionalisation basée sur le concept de « régime des débits naturels » : la méthode éco-géographique

Nous proposons une nouvelle méthode de régionalisation des débits fondée sur le concept de « régime des débits naturels » introduit en écologie aquatique : l’approche éco-géographique. Elle se distingue de deux approches de régionalisation existantes (approches hydrologique et écologique) sur les trois points suivants : le choix des variables hydrologiques, l’échelle d’analyse et la finalité de la régionalisation. En ce qui concerne le choix des variables hydrologiques, la nouvelle méthode est fondée sur le choix des caractéristiques des débits et non sur les variables hydrologiques. Ces caractéristiques des débits sont définies au moyen de l’analyse en composantes principales appliquée sur les variables hydrologiques. Contrairement aux autres approches, l’approche éco-géographique tient compte de toutes les caractéristiques des débits dans la régionalisation conformément au concept de « régime des débits naturels ». Quant à l’échelle d’analyse, à l’instar de l’approche écologique, la nouvelle méthode s’applique aussi à toutes les échelles d’analyse (annuelle, mensuelle et journalière) mais en les considérant séparément afin de tenir compte de toutes les caractéristiques de débits dans la régionalisation. Enfin, la finalité de la nouvelle méthode est de pouvoir déterminer les facteurs de variabilité spatiale des caractéristiques de débits (et non des variables hydrologiques) au moyen de l’analyse canonique des corrélations, notamment afin d’assurer une gestion durable des ressources hydriques dans un contexte de changement de l’environnement. Nous avons appliqué cette nouvelle méthode aux débits moyens annuels au Québec.Flow regionalization has been the subject of numerous hydrologic studies. However, despite the development of regionalization methods, there are still differences in the approaches used amongst hydrologists on the one hand, and between hydrologists and experts in other fields (aquatic ecology and physical geography) on the other hand. Those differences relate to five aspects of the regionalization process: the choice of hydrologic variables, station grouping methods to produce homogeneous hydrologic regions, the choice of appropriate statistical laws to estimate quantiles for non-gauged or partially-gauged sites, the scale of flow analysis, and the ultimate purpose of the regionalization exercise. Depending on the choice of hydrologic variables, the scale of analysis and their ultimate purpose, regionalization studies may thus be divided according to two distinct approaches: the hydrologic approach and the ecologic approach.The ultimate purpose of the hydrologic approach is to estimate flows at non-gauged or partially-gauged sites. For this reason, it has been primarily concerned with methods that allow the grouping of stations into homogeneous hydrologic regions and with the choice of statistical laws to estimate quantiles for non-gauged or partially-gauged sites. However, despite its undeniable interest from a practical point of view, this approach does not address the concerns of ecologists and geographers for three reasons: 1) the choice of hydrologic variables used for regionalization is not based on a scientific concept (this choice is arbitrary, and the variables selected do not constrain all the flow characteristics); 2) the ultimate purpose of the regionalization exercise is limited to estimating flows and is of limited interest to geographers and ecologists; 3) regionalization is performed at a daily scale, without taking into account other scales.To make up for these limitations, ecologists have recently proposed regionalization based on the “natural flow regime” concept (the ecologic approach), which allows all fundamental flow characteristics (magnitude, frequency, duration, timing of occurrence and variability) to be taken into account. The rationale for considering all flow characteristics is that each characteristic has an effect on the behaviour of river ecosystems. Hence, regionalization based on the ecologic approach relies on a large number of hydrologic variables that define the fundamental flow characteristics. Rather than being arbitrary, the choice of variable is based on this new paradigm. Regionalization using the ecologic approach considers all time scales, and its ultimate purpose is to account for differences in the structure and biological composition of aquatic ecosystems.However, one of the limitations of studies based on this approach is that, no matter how numerous they are, the variables used for regionalization do not constrain all flow characteristics, as required by the natural flow regime concept, so that application of this concept is incomplete. In addition, simultaneous analysis of all time scales does not allow consideration of all flow characteristics. To overcome these limitations, we propose a new regionalization approach based on the natural flow regime concept, an “ecogeographic” approach that differs from the ecologic approach in three ways. First, the proposed method is based on the use of flow characteristics rather than hydrologic variables. The reason for this is that there are an infinite number of hydrologic variables to define the five fundamental characteristics, making it impossible to account for all of them in the regionalization process. In contrast, since the number of fundamental flow characteristics is limited, they can all be taken into account, consistent with the “natural flow regime” requirements. Second, the ultimate purpose of the proposed regionalization method is to identify the physiographic and climatic factors that explain the spatial variability of these fundamental characteristics. To achieve this goal, it is necessary to analyze the different time scales (daily, monthly, annual) separately given the fact that it is impossible to constrain the effect of these various physiographic and climatic factors at all time scales. Indeed, some factors may show an effect at some time scales and not at others. This ultimate purpose addresses the concerns of geographers interested in explaining the spatial variability of such phenomena, among other things. Finally, separate analysis of the various time scales makes it possible to define all flow characteristics linked to a given time scale. As such, application of the “natural flow regime” concept to regionalization is complete.Application of the ecogeographical method involves four separate steps: 1) the definition of the flow characteristics for the hydrologic series of interest; 2) the determination of minor and major characteristics using principal component analysis, where a “major” flow characteristic is defined as one which meets the following criterion: TVE ≥ (100% / N), where N is the total number of characteristics that define the analyzed hydrologic series and TVE is the total variance explained; 3) the grouping of stations in homogeneous hydrologic regions based on factorial scores. Homogeneous hydrologic regions are divided in two types based on the presence or absence of stations: effective homogeneous regions contain stations whereas fictive homogenous regions do not; 4) the determination of the factors that affect the spatial variability of flow characteristics. This is achieved using canonical correlation analysis, an approach that we have applied to average annual flows in Quebec watersheds

Does the creation of a boreal hydroelectric reservoir result in a net change in evaporation?

AbstractEstimates of water consumption from hydroelectricity production are hampered by a lack of common methodological approaches. Studies typically use gross evaporation estimates which do not take into account the evaporative water loss from the pre-flooded ecosystems that would occur without the presence of a reservoir. We evaluate the net change in evaporation following the creation of a hydroelectric reservoir located in the Canadian boreal region. We use a direct measurement technique (eddy covariance) over four different ecosystems to evaluate the pre- and post-flood landscape water flux over a five-year period. The net effect of reservoir creation was to increase evaporation over that of the pre-flooded ecosystem. This change was dependent both on management and differences in the timing of the evaporation with nighttime and autumn contributing strongly to the reservoir evaporation. Managed reduction of water level, and thus the evaporating area, reduced the evaporation

Quantitative Magnetic Resonance Imaging of Cortical Multiple Sclerosis Pathology

Although significant improvements have been made regarding the visualization and characterization of cortical multiple sclerosis (MS) lesions using magnetic resonance imaging (MRI), cortical lesions (CL) continue to be under-detected in vivo, and we have a limited understanding of the causes of GM pathology. The objective of this study was to characterize the MRI signature of CLs to help interpret the changes seen in vivo and elucidate the factors limiting their visualization. A quantitative 3D high-resolution (350 μm isotropic) MRI study at 3 Tesla of a fixed post mortem cerebral hemisphere from a patient with MS is presented in combination with matched immunohistochemistry. Type III subpial lesions are characterized by an increase in T1, T2 and M0, and a decrease in MTR in comparison to the normal appearing cortex (NAC). All quantitative MR parameters were associated with cortical GM myelin content, while T1 showed the strongest correlation. The histogram analysis showed extensive overlap between CL and NAC for all MR parameters and myelin content. This is due to the poor contrast in myelin content between CL and NAC in comparison to the variability in myelo-architecture throughout the healthy cortex. This latter comparison is highlighted by the representation of T1 times on cortical surfaces at several laminar depths

Pharmacogenomics of the efficacy and safety of Colchicine in COLCOT

© 2021 The Authors. Circulation: Genomic and Precision Medicine is published on behalf of the American Heart Association, Inc., by Wolters Kluwer Health, Inc. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited and is not used for commercial purposes.Background: The randomized, placebo-controlled COLCOT (Colchicine Cardiovascular Outcomes Trial) has shown the benefits of colchicine 0.5 mg daily to lower the rate of ischemic cardiovascular events in patients with a recent myocardial infarction. Here, we conducted a post hoc pharmacogenomic study of COLCOT with the aim to identify genetic predictors of the efficacy and safety of treatment with colchicine. Methods: There were 1522 participants of European ancestry from the COLCOT trial available for the pharmacogenomic study of COLCOT trial. The pharmacogenomic study's primary cardiovascular end point was defined as for the main trial, as time to first occurrence of cardiovascular death, resuscitated cardiac arrest, myocardial infarction, stroke, or urgent hospitalization for angina requiring coronary revascularization. The safety end point was time to the first report of gastrointestinal events. Patients' DNA was genotyped using the Illumina Global Screening array followed by imputation. We performed a genome-wide association study in colchicine-treated patients. Results: None of the genetic variants passed the genome-wide association study significance threshold for the primary cardiovascular end point conducted in 702 patients in the colchicine arm who were compliant to medication. The genome-wide association study for gastrointestinal events was conducted in all 767 patients in the colchicine arm and found 2 significant association signals, one with lead variant rs6916345 (hazard ratio, 1.89 [95% CI, 1.52-2.35], P=7.41×10-9) in a locus which colocalizes with Crohn disease, and one with lead variant rs74795203 (hazard ratio, 2.51 [95% CI, 1.82-3.47]; P=2.70×10-8), an intronic variant in gene SEPHS1. The interaction terms between the genetic variants and treatment with colchicine versus placebo were significant. Conclusions: We found 2 genomic regions associated with gastrointestinal events in patients treated with colchicine. Those findings will benefit from replication to confirm that some patients may have genetic predispositions to lower tolerability of treatment with colchicine.info:eu-repo/semantics/publishedVersio

Inactivation of genes coding for mitochondrial Nd7 and Nd9 complex I subunits in Chlamydomonas reinhardtii. Impact of complex I loss on respiration and energetic metabolism.

In Chlamydomonas, unlike in flowering plants, genes coding for Nd7 (NAD7/49kDa) and Nd9 (NAD9/30kDa) core subunits of mitochondrial respiratory-chain complex I are nucleus-encoded. Both genes possess all the features that facilitate their expression and proper import of the polypeptides in mitochondria. By inactivating their expression by RNA interference or insertional mutagenesis, we show that both subunits are required for complex I assembly and activity. Inactivation of complex I impairs the cell growth rate, reduces the respiratory rate, leads to lower intracellular ROS production and lower expression of ROS scavenging enzymes, and is associated to a diminished capacity to concentrate CO2 without compromising photosynthetic capacity.Peer reviewe