SCRIPTORIUM (Université de Moncton)
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François-Olivier Dorais, L’école historique de Québec. Une histoire intellectuelle, Montréal, Boréal, 2022, 476 p.
No full textDepuis quelques années, le nom de François-Olivier Dorais est de plus en plus fréquemment associé à l’histoire intellectuelle au Québec et au sein des francophonies canadiennes. Les férus d’historiographie se souviendront certainement de son Un historien dans la Cité. Gaétan Gervais et l’Ontario français, paru en 2016.udemauteur: Julien Massicott
Platelet-derived microparticles provoke chronic lymphocytic leukemia malignancy through metabolic reprogramming
No full textIt is well established that inflammation and platelets promote multiple processes of cancer malignancy. Recently, platelets have received attention for their role in carcinogenesis through the production of microvesicles or platelet-derived microparticles (PMPs), which transfer their biological content to cancer cells. We have previously characterized a new subpopulation of these microparticles (termed mito-microparticles), which package functional mitochondria. The potential of mitochondria transfer to cancer cells is particularly impactful as many aspects of mitochondrial biology (i.e., cell growth, apoptosis inhibition, and drug resistance) coincide with cancer hallmarks and disease progression. These metabolic aspects are particularly notable in chronic lymphocytic leukemia (CLL), which is characterized by a relentless accumulation of proliferating, immunologically dysfunctional, mature B-lymphocytes that fail to undergo apoptosis. The present study aimed to investigate the role of PMPs on CLL metabolic plasticity leading to cancer cell phenotypic changes.CLL cell lines were co-incubated with different concentrations of human PMPs, and their impact on cell proliferation, mitochondrial DNA copy number, OCR level, ATP production, and ROS content was evaluated. Essential genes involved in metabolic-reprogramming were identified using the bioinformatics tools, examined between patients with early and advanced CLL stages, and then validated in PMP-recipient CLLs. Finally, the impact of the induced metabolic reprogramming on CLLs’ growth, survival, mobility, and invasiveness was tested against anti-cancer drugs Cytarabine, Venetoclax, and Plumbagin.The data demonstrated the potency of PMPs in inducing tumoral growth and invasiveness in CLLs through mitochondrial internalization and OXPHOS stimulation which was in line with metabolic shift reported in CLL patients from early to advanced stages. This metabolic rewiring also improved CLL cells' resistance to Cytarabine, Venetoclax, and Plumbagin chemo drugs.Altogether, these findings depict a new platelet-mediated pathway of cancer pathogenesis. We also highlight the impact of PMPs in CLL metabolic reprogramming and disease progression.udemauteur: Ehsan Gharib; Vanessa Veilleux; Luc H. Boudreau; Nicolas Pichaud; Gilles A. Robichau
Involvement of calmodulin-dependent protein kinase I in the regulation of the expression of connexin 43 in MA-10 tumor Leydig cells
No full textConnexin 43 (Cx43, also known as Gja1) is the most abundant testicular gap junction protein. It has a crucial role in the support of spermatogenesis by Sertoli cells in the seminiferous tubules as well as in androgen synthesis by Leydig cells. The multifunctional family of Ca2+/calmodulin-dependent protein kinases (CaMK) is composed of CaMK I, II, and IV and each can serve as a mediator of nuclear Ca2+ signals. These kinases can control gene expression by phosphorylation of key regulatory sites on transcription factors. Among these, AP-1 members cFos and cJun are interesting candidates that seem to cooperate with CaMKs to regulate Cx43 expression in Leydig cells. In this study, the Cx43 promoter region important for CaMK-dependent activation is characterized using co-transfection of plasmid reporter-constructs with different plasmids coding for CaMKs and/or AP-1 members in MA-10 Leydig cells. Here we report that the activation of Cx43 expression by cFos and cJun is increased by CaMKI. Furthermore, results from chromatin immunoprecipitation suggest that the recruitment of AP-1 family members to the proximal region of the Cx43 promoter may involve another uncharacterized AP-1 DNA regulatory element and/or protein–protein interactions with other partners. Thus, our data provide new insights into the molecular regulatory mechanisms that control mouse Cx43 transcription in testicular Leydig cells.udemauteur: Luc Marti
Diet flexibility of wolves and black bears in the range of migratory caribou
No full textThe diet of predators can be highly variable, which is exemplified by their ability to acclimate to a wide range of ecological conditions. Such flexibility in foraging may be a key aspect of their performance in unpredictable environments such as at the edge of the range of a species or where food availability varies greatly in time and space. Gaining information on the diets of predators under such conditions could foster our comprehension of their ecological flexibility and the potential role of predation on the population dynamics of prey. We determined the diet of wolves (Canis lupus) and black bears (Ursus americanus) in northern Québec and Labrador (Canada) within the range of two migratory caribou (Rangifer tarandus) herds: the high-abundance Rivière-aux-Feuilles herd (RFH) and low-abundance Rivière-George herd (RGH). Worldwide, decline in caribou populations has become a concern, stressing the need to better understand the factors involved in these declines, including predation. In northern Québec (RFH range), caribou was the primary year-round prey of wolves while moose (Alces alces) and muskoxen (Ovibos moschatus) were consumed in some sectors. The diet of wolves in northern Labrador (RGH range) varied seasonally, with caribou, moose, and fish as main prey during different periods throughout the year. Black bear diets varied seasonally and regionally. Among the foods we analyzed, caribou was the main source of animal protein for bears in northern Québec and northern Labrador, except during a high abundance of Ungava collared lemming (Dicrostonyx hudsonius). Only bears in northern Québec ate caribou during late summer/fall. Our results highlight the diet flexibility of wolves and black bears in northern food webs, and how their diets change in relation to the distribution and abundance of prey. Our results will help quantify the potential impact of these predators on prey populations in northern systems.udemauteur: Nicolas Lecomt
Age-related flexibility of energetic metabolism in the honey bee Apis mellifera
No full textThe mechanisms that underpin aging are still elusive. In this study, we suggest that the ability of mitochondria to oxidize different substrates, which is known as metabolic flexibility, is involved in this process. To verify our hypothesis, we used honey bees (Apis mellifera carnica) at different ages, to assess mitochondrial oxygen consumption and enzymatic activities of key enzymes of the energetic metabolism as well as ATP5A1 content (subunit of ATP synthase) and adenylic energy charge (AEC). We also measured mRNA abundance of genes involved in mitochondrial functions and the antioxidant system. Our results demonstrated that mitochondrial respiration increased with age and favored respiration through complexes I and II of the electron transport system (ETS) while glycerol-3-phosphate (G3P) oxidation was relatively decreased. In addition, glycolytic, tricarboxylic acid cycle and ETS enzymatic activities increased, which was associated with higher ATP5A1 content and AEC. Furthermore, we detected an early decrease in the mRNA abundance of subunits of NADH ubiquinone oxidoreductase subunit B2 (NDUFB2, complex I), mitochondrial cytochrome b (CYTB, complex III) of the ETS as well as superoxide dismutase 1 and a later decrease for vitellogenin, catalase and mitochondrial cytochrome c oxidase subunit 1 (COX1, complex IV). Thus, our study suggests that the energetic metabolism is optimized with aging in honey bees, mainly through quantitative and qualitative mitochondrial changes, rather than showing signs of senescence. Moreover, aging modulated metabolic flexibility, which might reflect an underpinning mechanism that explains lifespan disparities between the different castes of worker bees.udemauteur: Etienne Hebert-Chatelain; Simon Lamarre; Nicolas Pichau
Suivi du crabe vert (Carcinus maenas) par détection de l'ADN environnemental: validation de l'approche et détection dans la région de Miramichi au Nouveau-Brunswick
Get PDFLes espèces aquatiques envahissantes peuvent être retrouvés à la grandeur du globe. Après s’être installées dans un nouvel environnement, ces espèces peuvent engendrer des impacts environnementaux et économiques. Pour détecter et surveiller ces espèces, des méthodes traditionnelles de suivi comme le trappage et la pêche sont utilisées, mais ne sont pas toujours efficaces et peuvent être longues. Notre objectif de recherche était de déterminer si la rivière Miramichi constituait une barrière écologique contre l’avancée du crabe vert (Carcinus maenas) vers le Nouveau-Brunswick (N-B). En effet, la littérature documente une barrière potentielle à l’embouchure du sud de la rivière, où un tourbillon marin a été observé, ce qui représenterait un obstacle pour la dispersion larvaire de l’espèce. Pour ce faire, nous avons utilisé une approche novatrice de détection de l’ADN environnemental (ADNe) de l’espèce à partir d’échantillons d’eau. Nous avons d’abord validé notre approche spécifique à l’espèce à l’aide d’échantillons d’eau récoltés à Shédiac à des sites ayant un fort historique de présence du crabe vert. Nous avons ensuite récolté des échantillons d’eau le long de la côte nord et sud de la rivière Miramichi afin d’évaluer la distribution de l’espèce de façon hebdomadaire durant un mois. À chaque récolte, des variables environnementales comme la température de l’eau, la salinité, l’oxygène dissous et la turbidité ont été mesurées. Tous les échantillons d’eau ont été filtrés dans un délai de 24h et l’ADNe contenu dans les filtres a été extrait. L’ADNe a ensuite été utilisé dans des tests de réaction de polymérase en chaine quantitative (qPCR) pour signaler la détection ou non de l’espèce. Avec les données de présence du crabe vert, nous avons exploré s’il y avait des associations possibles entre les variables environnementales et la présence du crabe vert parmi les différents sites d’échantillonnage. Nos résultats ont révélé que notre approche est efficace pour détecter l’ADN du crabe vert dans un échantillon d’eau. Cependant, aucune détection n’a été signalée aux sites le long de la rivière Miramichi. Il a été impossible de faire des associations compte tenu de l’absence de détection et de la grande variabilité des variables mesurées. Ainsi, il est encore incertain si la rivière Miramichi représente une barrière écologique pour l’avancée du crabe vert. Cette étude est l’une des rares ayant tenté de détecter l’ADNe d’un crustacé. Elle détaille les démarches à suivre pour appliquer cette approche et documente aussi les méthodes à suivre pour améliorer la concentration en ADNe pour un crustacé, ainsi que les variables à considérer en milieu côtier
Understanding financial professionals' perceptions of their clients financial behaviors
No full textPurpose: This article describes financial professionals' perceptions of their clients' financial behaviors and the explanatory factors underlying these behaviors. Design/methodology/approach: In this qualitative research, the authors seek to understand financial professionals' experiences in relation to how their clients manage their own finances. The authors conduct and analyze 26 semi-structured interviews with financial professionals from several industries within the financial sector in Canada. Findings: The professionals in this study noted that despite their clients' financial knowledge, several other factors can explain these individuals' financial behaviors. They include psychological factors (such as financial bias, the need for instant gratification, and the lack of awareness regarding the long-term effects of certain types of financial behaviors), financial habits (such as lifestyle, financial planning and lack of discipline) and the financial system's flexibility with respect to debt financing and repayment. These perceptions are categorized according to whether they are related to debt financing or repayment, savings or investments. Originality/value: By using a qualitative methodology that relies on the perceptions of financial professionals, this study aims to better understand the financial behaviors of individuals and households, and these behaviors' underlying factors. This study's findings could be useful to various stakeholders interested, in one way or another, in financial literacy, such as organizations aiming to strengthen and promote financial literacy, educators, researchers, regulatory bodies of financial institutions and financial advisers.udemauteur: Tania Morris; Lamine Kamano; Stéphanie Maille
Modélisation univariée et multivariée des courbes Intensité - Durée - Fréquence (IDF) des pluies - Application à la région du Grand Moncton
Get PDFCette thèse de maîtrise a pour objectif d’analyser le comportement des valeurs extrêmes de pluie, par les courbes Intensité – Durée – Fréquence (IDF), au travers plusieurs séries maximales annuelles de pluies de durées d’agrégation entre 5 minutes et 24 heures. Deux approches fréquentielles, issues de la théorie des valeurs extrêmes univarié et multivariée, ont été proposés pour l’estimation des quantiles marginales et conditionnels : Une approche univariée basée sur le modèle des valeurs extrêmes généralisé (GEV, et une deuxième basée sur les copules multivariées de type vigne. Le cadre univarié, réellement un sous-cadre cadre de la modélisation multivariée, est classiquement utilisé pour raisons simplificatrices. Nous avons comparé les estimateurs des quantiles, ainsi que les incertitudes associées, obtenus par ces deux approches. Une illustration est introduite pour l’estimation des courbes IDF au niveau de la station météorologique de Moncton. Les résultats ont montré le grand avantage de l’approche multivariée. En effet, l’estimation des courbes IDF basée sur les copules Vines a montré une estimation plus grande par rapport à l’approche marginale Par conséquent, cela permet une estimation moins biaisée et pourra aider pour une gestion éclairée des évènements pluviométriques extrêmes et du risque associé. Mots-clés : Théories des valeurs extrêmes, Analyse fréquentielle, Maxima annuels, Modèle GEV, dépendance, Copules vines, Quantiles, courbes IDF, Moncton
Sinapic and ferulic acid phenethyl esters increase the expression of steroidogenic genes in MA-10 tumor Leydig cells
No full textDuring aging, the production of androgens by the testis Leydig cells gradually decreases. Phenolic compounds can improve testosterone biosynthesis and delay the onset of hypogonadal symptoms in males. In this study, sinapic acid phenethyl ester was evaluated for its ability to regulate gene expression and steroid production in Leydig cells. Specifically, the effects of this ester on the transcriptome of MA-10 Leydig cells were investigated by RNA-Seq. To better establish a structure-function relationship of the hydroxy-methoxyphenyl moiety of sinapic and phenethyl ester, its influences on gene expression were compared to those of its ferulic acid phenethyl ester analogue. According to the transcriptomic analysis, most genes encoding enzymes related to cholesterol biosynthesis are increased in response to sinapic acid phenethyl ester treatment of MA-10 Leydig cells. Interestingly, treatments with 10 μM of ferulic acid phenethyl ester increased cAMP-dependent Star promoter activation, gene expression and protein levels. In addition, treatments of MA-10 Leydig cells with 10 μM of sinapic or ferulic acid phenethyl ester resulted in increased progesterone production. Thus, our results indicate that sinapic and ferulic acid phenethyl esters can improve cholesterol and steroid biosynthesis in testicular Leydig cells.udemauteur: Mohamed Touaibia; Luc Marti
Caffeic acid phenethyl ester analogues as selective inhibitors of 12-lipoxygenase product biosynthesis in human platelets
No full textThe inflammatory response is an essential process for the host defence against pathogens. Lipid mediators are important in coordinating the pro-inflammatory and pro-resolution phases of the inflammatory process. However, unregulated production of these mediators has been associated with chronic inflammatory diseases such as arthritis, asthma, cardiovascular diseases, and several types of cancer. Therefore, it is not surprising that enzymes implicated in the production of these lipid mediators have been targeted for potential therapeutic approaches. Amongst these inflammatory molecules, the 12-hydroxyeicosatetraenoic acid (12(S)-HETE) is abundantly produced in several diseases and is primarily biosynthesized via the platelet's 12-lipoxygenase (12-LO) pathway. To this day, very few compounds selectively inhibit the 12-LO pathway, and most importantly, none are currently used in the clinical settings. In this study, we investigated a series of polyphenol analogues of natural polyphenols that inhibit the 12-LO pathway in human platelets without affecting other normal functions of the cell. Using an ex vivo approach, we found one compound that selectively inhibited the 12-LO pathway, with IC50 values as low as 0.11 µM, with minimal inhibition of other lipoxygenase or cyclooxygenase pathways. More importantly, our data show that none of the compounds tested induced significant off-target effects on either the platelet's activation or its viability. In the continuous search for specific and better inhibitors targeting the regulation of inflammation, we characterized two novel inhibitors of the 12-LO pathway that could be promising for subsequent in vivo studies.udemauteur: Mathieu Hébert; Jérémie Doiron; Mohamed Touaibia; Marc Surette; Luc Boudrea