Caractérisation de sacsine, la protéine responsable de l'ataxie de Charlevoix-Saguenay

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Formation artistique et contexte social des peintres canadiens à Paris (1887-1895)

Ce projet de mémoire entreprend de montrer dans quelles conditions artistiques et sociales ont évolués cinq peintres canadiens à Paris à la fin du XIXe siècle. Les artistes à l'origine de la décoration de la chapelle Sacré-Coeur de l'église Notre-Dame\ud de Montréal; Henri Beau, Joseph Franchère, Charles Gill, Ludger Larose ainsi que Joseph Saint-Charles, se présentent ici, comme un prétexte à l'étude du parcours emprunté par nombreux peintres canadiens à Paris à cette époque. Le choix de la période d'étude est déterminé par le début de leur séjour en France et par la fin du projet de décoration de la chapelle (1887-1895). Dans un premier temps, la recherche dresse un portrait du contexte de formation dans lequel ils ont progressé. À ce propos, l'École Nationale Spéciale des Beaux-Arts, l'Académie Julian et Colarossi sont les principales institutions fréquentées par les artistes. Dans un deuxième temps, cette étude établit quelles étaient leurs conditions de vie et occupations sociales à Paris. Pour ce faire, elle définit leur situation économique par le type d'habitation dans lequel ils vivaient et leur emplacement. Quant à leur vie sociale comme étrangers, elle est reconstituée à partir des lieux et des personnes qu'ils côtoyaient. Dans un dernier temps, ce mémoire entreprend d'illustrer dans quelle mesure leur passage dans la capitale mondiale de l'art a influencé leur carrière artistique au Canada. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Henri Beau, Joseph-Charles Franchère, Charles Gill, Ludger Larose, Joseph Saint-Charles, Académies, Paris, Chapelle du Sacré-Coeur, Montréal

ATXR5 and ATXR6 are H3K27 monomethyltransferases required for chromatin structure and gene silencing.

Constitutive heterochromatin in Arabidopsis thaliana is marked by repressive chromatin modifications, including DNA methylation, histone H3 dimethylation at Lys9 (H3K9me2) and monomethylation at Lys27 (H3K27me1). The enzymes catalyzing DNA methylation and H3K9me2 have been identified; alterations in these proteins lead to reactivation of silenced heterochromatic elements. The enzymes responsible for heterochromatic H3K27me1, in contrast, remain unknown. Here we show that the divergent SET-domain proteins ARABIDOPSIS TRITHORAX-RELATED PROTEIN 5 (ATXR5) and ATXR6 have H3K27 monomethyltransferase activity, and atxr5 atxr6 double mutants have reduced H3K27me1 in vivo and show partial heterochromatin decondensation. Mutations in atxr5 and atxr6 also lead to transcriptional activation of repressed heterochromatic elements. Notably, H3K9me2 and DNA methylation are unaffected in double mutants. These results indicate that ATXR5 and ATXR6 form a new class of H3K27 methyltransferases and that H3K27me1 represents a previously uncharacterized pathway required for transcriptional repression in Arabidopsis

Prevalence of insomnia and its treatment in Canada

Objectives : To estimate the prevalence of insomnia and examine its correlates (for example, demographics and physical and mental health) and treatments. Methods : A sample of 2000 Canadians aged 18 years and older responded to a telephone survey about sleep, health, and the use of sleep-promoting products. Respondents with insomnia were identified using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, and the International Classification of Diseases, Tenth Edition, criteria. Results : Among the sample, 40.2% presented at least 1 symptom of insomnia (that is, trouble falling or staying asleep, or early morning awakening) for a minimum of 3 nights per week in the previous month, 19.8% were dissatisfied with their sleep, and 13.4% met all criteria for insomnia (that is, presence of 1 insomnia symptom 3 nights or more per week for at least 1 month, accompanied by distress or daytime impairment). Insomnia was associated with female sex, older age, and poorer self-rated physical and mental health. Thirteen per cent of respondents had consulted a health care provider for sleep difficulties once in their lifetime. Moreover, 10% had used prescribed medications for sleep in the previous year, 9.0% used natural products, 5.7% used over-the-counter products, and 4.6% used alcohol. There were differences between French- and English-speaking adults, with the former group presenting lower rates of insomnia (9.5%, compared with 14.3%) and consultation (8.7%, compared with 14.4%), but higher rates of prescribed medications (12.9%, compared with 9.3%) and the use of natural products (15.6%, compared with 7.4%). Conclusions : Insomnia is a prevalent condition, although few people seek professional consultation for this condition. Despite regional differences in the prevalence and treatments used to manage insomnia, prescribed medications remain the most widely used therapeutic option.Objectifs : Estimer la prévalence de l'insomnie et examiner ses corrélats (par exemple, les données démographiques et la santé physique et mentale) et les traitements. Méthodes : Un échantillon de 2000 Canadiens de 18 ans et plus ont répondu à une enquête téléphonique sur le sommeil, la santé et l'utilisation de produits qui favorisent le sommeil. Les répondants souffrant d'insomnie ont été identifiés à l'aide des critères du Manuel diagnostique et statistique des troubles mentaux, 4e édition révisée, et de la Classification internationale des maladies, 10e édition. Résultats : Dans l'échantillon, 40,2 % présentaient au moins 1 symptôme d'insomnie (c'est-à-dire, difficulté à s'endormir ou à rester endormi, ou réveil tôt le matin) pour un minimum de 3 nuits par semaine durant le mois précédent, 19,8 % étaient insatisfaits de leur sommeil, et 13,4 % satisfaisaient à tous les critères de l'insomnie (c'est-à-dire, la présence d'un symptôme d'insomnie 3 nuits ou plus par semaine pendant au moins 1 mois, accompagnée de détresse ou d'incapacité durant le jour). L'insomnie était associée avec le sexe féminin, l'âge avancé, et une mauvaise santé physique et mentale auto-déclarée. Treize pour cent des répondants avaient consulté un prestataire de soins de santé pour des difficultés de sommeil une fois dans leur vie. En outre, 10 % avaient utilisé des médicaments prescrits pour le sommeil dans l'année précédente, 9,0 % avaient utilisé des produits naturels, 5,7 % avaient utilisé des produits en vente libre, et 4,6 % avaient utilisé de l'alcool. Il y avait des différences entre les adultes francophones et anglophones, le premier groupe présentant des taux plus faibles d'insomnie (9,5 %, comparé à 14,3 %) et de consultations (8,7 %, comparé à 14,4 %), mais des taux plus élevés de médicaments prescrits (12,9 %, comparé à 9,3 %) et d'utilisation de produits naturels (15,6 %, comparé à 7,4 %). Conclusions : L'insomnie est une affection prévalente, bien que peu de gens aient recours à une consultation professionnelle pour ce problème. Malgré des différences régionales de prévalence et des traitements utilisés pour gérer l'insomnie, les médicaments prescrits demeurent l'option thérapeutique la plus utilisée

Monthly fluctuations of insomnia symptoms in a population-based sample

Study Objectives: To document the monthly changes in sleep/insomnia status over a 12-month period; to determine the optimal time intervals to reliably capture new incident cases and recurrent episodes of insomnia and the likelihood of its persistence over time. Design: Participants were 100 adults (mean age = 49.9 years; 66% women) randomly selected from a larger population-based sample enrolled in a longitudinal study of the natural history of insomnia. They completed 12 monthly telephone interviews assessing insomnia, use of sleep aids, stressful life events, and physical and mental health problems in the previous month. A total of 1,125 interviews of a potential 1,200 were completed. Based on data collected at each assessment, participants were classified into one of three subgroups: good sleepers, insomnia symptoms, and insomnia syndrome. Results: At baseline, 42 participants were classified as good sleepers, 34 met criteria for insomnia symptoms, and 24 for an insomnia syndrome. There were significant fluctuations of insomnia over time, with 66% of the participants changing sleep status at least once over the 12 monthly assessments (51.5% for good sleepers, 59.5% for insomnia syndrome, and 93.4% for insomnia symptoms). Changes of status were more frequent among individuals with insomnia symptoms at baseline (mean = 3.46, SD = 2.36) than among those initially classified as good sleepers (mean = 2.12, SD = 2.70). Among the subgroup with insomnia symptoms at baseline, 88.3% reported improved sleep (i.e., became good sleepers) at least once over the 12 monthly assessments compared to 27.7% whose sleep worsened (i.e., met criteria for an insomnia syndrome) during the same period. Among individuals classified as good sleepers at baseline, risks of developing insomnia symptoms and syndrome over the subsequent months were, respectively, 48.6% and 14.5%. Monthly assessment over an interval of 6 months was found most reliable to estimate incidence rates, while an interval of 3 months proved the most reliable for defining chronic insomnia. Conclusions: Monthly assessment of insomnia and sleep patterns revealed significant variability over the course of a 12-month period. These findings highlight the importance for future epidemiological studies of conducting repeated assessment at shorter than the typical yearly interval in order to reliably capture the natural course of insomnia over time

The natural history of insomnia : a population-based 3-year longitudinal study

Background Despite its high prevalence, little information is available about the natural history of insomnia. The extent to which episodes of insomnia will persist or remit over time is difficult to predict. We examined the natural history of insomnia and describe the most common trajectories over 3 years. Methods Three hundred eighty-eight adults (mean [SD] age, 44.8 [13.9] years; 61% women) were selected from a larger population-based sample on the basis of the presence of insomnia at baseline. They completed standardized sleep/insomnia questionnaires at 3 annual follow-up assessments. For each follow-up assessment, participants were classified into 1 of 3 groups (individuals with an insomnia syndrome, individuals with insomnia symptoms, and individuals with good sleep) on the basis of algorithms using standard diagnostic criteria for insomnia. Rates of persistent insomnia, remission, and relapse were computed for each group. Results Of the study sample, 74% reported insomnia for at least 1 year (2 consecutive assessments) and 46% reported insomnia persisting over the entire 3-year study. The course of insomnia was more likely to be persistent in those with more severe insomnia at baseline (ie, insomnia syndrome) and in women and older adults. Remission rate was 54%; however, 27% of those with remission of insomnia eventually experienced relapse. Individuals with subsyndromal insomnia at baseline were 3 times more likely to remit than worsen to syndrome status, although persistence was the most frequent course in that group as well. Conclusion These findings indicate that insomnia is often a persistent condition, in particular when it reaches the diagnostic threshold for an insomnia disorder

H3.1K27me1 maintains transcriptional silencing and genome stability by preventing GCN5-mediated histone acetylation

Epigenetic mechanisms play diverse roles in the regulation of genome stability in eukaryotes. In Arabidopsis thaliana, genome stability is maintained during DNA replication by the H3.1K27 methyltransferases ARABIDOPSIS TRITHORAX-RELATED PROTEIN 5 (ATXR5) and ATXR6, which catalyze the deposition of K27me1 on replication-dependent H3.1 variants. The loss of H3.1K27me1 in atxr5 atxr6 double mutants leads to heterochromatin defects, including transcriptional de-repression and genomic instability, but the molecular mechanisms involved remain largely unknown. In this study, we identified the transcriptional co-activator and conserved histone acetyltransferase GCN5 as a mediator of transcriptional de-repression and genomic instability in the absence of H3.1K27me1. GCN5 is part of a SAGA-like complex in plants that requires the GCN5-interacting protein ADA2b and the chromatin remodeler CHR6 to mediate the heterochromatic defects in atxr5 atxr6 mutants. Our results also indicate that Arabidopsis GCN5 acetylates multiple lysine residues on H3.1 variants, but H3.1K27 and H3.1K36 play essential functions in inducing genomic instability in the absence of H3.1K27me1. Finally, we show that H3.1K36 acetylation by GCN5 is negatively regulated by H3.1K27me1 in vitro. Overall, this work reveals a key molecular role for H3.1K27me1 in maintaining transcriptional silencing and genome stability in heterochromatin by restricting GCN5-mediated histone acetylation in plants

Male fertility in Arabidopsis requires active DNA demethylation of genes that control pollen tube function.

Active DNA demethylation is required for sexual reproduction in plants but the molecular determinants underlying this epigenetic control are not known. Here, we show in Arabidopsis thaliana that the DNA glycosylases DEMETER (DME) and REPRESSOR OF SILENCING 1 (ROS1) act semi-redundantly in the vegetative cell of pollen to demethylate DNA and ensure proper pollen tube progression. Moreover, we identify six pollen-specific genes with increased DNA methylation as well as reduced expression in dme and dme;ros1. We further show that for four of these genes, reinstalling their expression individually in mutant pollen is sufficient to improve male fertility. Our findings demonstrate an essential role of active DNA demethylation in regulating genes involved in pollen function

L’impact de l’isolement social engendré par la covid-19 sur le fonctionnement cognitif et la capacité à réaliser les activités des personnes aînées vivant avec un trouble neurocognitif : résultats d’une étude de portée

La pandémie de la COVID-19 a entraîné la mise en place de plusieurs mesures sociosanitaires. À notre connaissance, aucune recension des écrits ne s’est intéressée aux impacts de ces mesures sur le fonctionnement cognitif et la capacité à réaliser des activités du quotidien, notamment chez les personnes aînées vivant avec un trouble neurocognitif (TNC). Le but de cette étude de portée est donc d’explorer les impacts de l’isolement social prolongé, causé par la COVID-19, sur le fonctionnement cognitif et la capacité à réaliser les activités du quotidien des personnes aînées vivant avec un TNC. L’étude de portée utilisant la méthode de Arksey et O’Malley a été réalisée dans cinq banques de données (MedLine, APA PsycInfo, Cinahl, AgeLine et Abstract in Social Gerontology), à partir de 22 mots clés. Les 31 articles inclus dans cette étude de portée montrent une augmentation du déclin cognitif général (n = 23 ; 74,2 %), de même qu’une diminution de la capacité à réaliser les activités du quotidien (n = 20 ; 64,5 %), principalement au niveau des loisirs (n = 7 ; 22,6 %) et des soins personnels (n = 6 ; 19,3 %). Ces impacts sont dus à une diminution des opportunités de stimulation cognitive consécutive à l’isolement social prolongé et à l’interruption des services de santé et de soutien offerts à cette clientèle. Il importe de développer et de mettre en place des interventions permettant de prévenir les pertes cognitives et la capacité à réaliser les activités du quotidien dans l’éventualité où un isolement social prolongé serait imposé, afin de favoriser le bien-être de cette clientèle. ---- Public health measures were implemented during the COVID-19 pandemic. To our knowledge, no literature review has focused on the impacts of these measures on cognitive functioning, nor on the realization of activities in older adults living with a neurocognitive disorder (NCD). Hence, this scoping review explores the impacts of prolonged periods of social isolation caused by the COVID-19 pandemic on cognitive functioning in older adults living with a NCD and their ability to carry out daily activities. From 22 keywords, 31 articles were retrieved from five electronic databases. Results: Most of the participants in the included studies were living with a NCD (n = 24; 77.4%). Evidence suggests that a decrease in cognitive stimulation opportunities, an augmentation of periods of social isolation, and an interruption of healthcare services and support generate a general cognitive decline (n = 23; 74.2%), as well as an augmentation of difficulties performing daily activities (n = 20; 64.5%), mainly leisure activities (n = 7; 22.6%) and personal care (n = 6; 19.3%). The results of the present study show the importance of developing and implementing alternatives that will prevent cognitive loss and the realization of activities if another prolonged period of social isolation is imposed