La violence dans les relations amoureuses des adolescentes et des adolescents : une analyse prospective des facteurs de risque

Ce mémoire s’intéresse à la problématique de la violence entre partenaires amoureux adolescents. Il vise d’abord à vérifier les postulats émis dans le cadre d’études majoritairement rétrospectives concernant la présence d’interactions violentes entre partenaires, qui peuvent non seulement commencer dès le début des premières relations amoureuses mais aussi se poursuivre au sein de relations ultérieures. La stabilité des expériences de violence dans le temps est donc évaluée prospectivement sur une période de douze mois auprès d’un échantillon d’adolescents âgés en moyenne de 14,4 ans lors du premier moment de mesure. La présente étude vise également à identifier les facteurs de risque mesurés en troisième secondaire qui permettent de prédire qui seront les filles victimes et les garçons qui utiliseront de la violence envers leur partenaire au cours de l’année suivante. Les résultats n’ont pu confirmer la présence de stabilité de la violence dans le temps entre partenaires adolescents et les facteurs de risque ont affiché un faible potentiel de prédiction de la violence une année plus tard. Les données sont commentées en fonction des caractéristiques spécifiques reliées à la période de développement qu’est l’adolescence

The ribosomal protein RACK1 is required for microRNA function in both C. elegans and humans

Despite the importance of microRNAs (miRNAs) in gene regulation, it is unclear how the miRNA-Argonaute complex-or miRNA-induced silencing complex (miRISC)-can regulate the translation of their targets in such diverse ways. We demonstrate here a direct interaction between the miRISC and the ribosome by showing that a constituent of the eukaryotic 40S subunit, receptor for activated C-kinase (RACK1), is important for miRNA-mediated gene regulation in animals. In vivo studies demonstrate that RACK1 interacts with components of the miRISC in nematodes and mammals. In both systems, the alteration of RACK1 expression alters miRNA function and impairs the association of the miRNA complex with the translating ribosomes. Our data indicate that RACK1 can contribute to the recruitment of miRISC to the site of translation, and support a post-initiation mode of miRNA-mediated gene repression. © 2011 European Molecular Biology Organization

Modular organization of the white spruce (Picea glauca) transcriptome reveals functional organization and evolutionary signatures

Transcript profiling has shown the molecular bases of several biological processes in plants but few studies have developed an understanding of overall transcriptome variation. We investigated transcriptome structure in white spruce (Picea glauca), aiming to delineate its modular organization and associated functional and evolutionary attributes. Microarray analyses were used to: identify and functionally characterize groups of co-expressed genes; investigate expressional and functional diversity of vascular tissue preferential genes which were conserved among Picea species, and identify expression networks underlying wood formation. We classified 22 857 genes as variable (79%; 22 coexpression groups) or invariant (21%) by profiling across several vegetative tissues. Modular organization and complex transcriptome restructuring among vascular tissue preferential genes was revealed by their assignment to coexpression groups with partially overlapping profiles and partially distinct functions. Integrated analyses of tissue-based and temporally variable profiles identified secondary xylem gene networks, showed their remodelling over a growing season and identified PgNAC-7 (no apical meristerm (NAM), Arabidopsis transcription activation factor (ATAF) and cup-shaped cotyledon (CUC) transcription factor 007 in Picea glauca) as a major hub gene specific to earlywood formation. Reference profiling identified comprehensive, statistically robust coexpressed groups, revealing that modular organization underpins the evolutionary conservation of the transcriptome structure. © 2015 The Authors

Insect herbivory (Choristoneura fumiferana, Tortricidea) underlies tree population structure (Picea glauca, Pinaceae)

Variation in insect herbivory can lead to population structure in plant hosts as indicated by defence traits. In annual herbaceous, defence traits may vary between geographic areas but evidence of such patterns is lacking for long-lived species. This may result from the variety of selection pressures from herbivores, long distance gene flow, genome properties, and lack of research. We investigated the antagonistic interaction between white spruce (Picea glauca) and spruce budworm (SBW, Choristoneura fumiferana) the most devastating forest insect of eastern North America in common garden experiments. White spruces that are able to resist SBW attack were reported to accumulate the acetophenones piceol and pungenol constitutively in their foliage. We show that levels of these acetophenones and transcripts of the gene responsible for their release is highly heritable and that their accumulation is synchronized with the most devastating stage of SBW. Piceol and pungenol concentrations negatively correlate with rate of development in female SBW and follow a non-random geographic variation pattern that is partially explained by historical damage from SBW and temperature. Our results show that accumulation of acetophenones is an efficient resistance mechanism against SBW in white spruce and that insects can affect population structure of a long-lived plant

Coping with Environmental Constraints: Geographically Divergent Adaptive Evolution and Germination Plasticity in the Transcontinental \u3cem\u3ePopulus tremuloides\u3c/em\u3e

Societal Impact Statement Syntheses clearly show that global warming is affecting ecosystems and biodiversity around the world. New methods and measures are needed to predict the climate resilience of plant species critical to ecosystem stability, to improve ecological management and to support habitat restoration and human well-being. Widespread keystone species such as aspen are important targets in the study of resilience to future climate conditions because they play a crucial role in maintaining various ecosystem functions and may contain genetic material with untapped adaptive potential. Here, we present a new framework in support of climate-resilient revegetation based on comprehensively understood patterns of genetic variation in aspen. Summary Elucidating species\u27 genetic makeup and seed germination plasticity is essential to inform tree conservation efforts in the face of climate change. Populus tremuloides Michx. (aspen) occurs across diverse landscapes and reaches from Alaska to central Mexico, thus representing an early-successional model for ecological genomics. Within drought-affected regions, aspen shows ploidy changes and/or shifts from sexual to clonal reproduction, and reduced diversity and dieback have already been observed. We genotyped over 1000 individuals, covering aspen\u27s entire range, for approximately 44,000 single-nucleotide polymorphisms (SNPs) to assess large-scale and fine-scale genetic structure, variability in reproductive type (sexual/clonal), polyploidy and genomic regions under selection. We developed and implemented a rapid and reliable analysis pipeline (FastPloidy) to assess the presence of polyploidy. To gain insights into plastic responses, we contrasted seed germination from western US and eastern Canadian natural populations under elevated temperature and water stress. Four major genetic clusters were identified range wide; a preponderance of triploids and clonemates was found within western and southern North American regions, respectively. Genomic regions involving approximately 1000 SNPs under selection were identified with association to temperature and precipitation variation. Under drought stress, western US genotypes exhibited significantly lower germination rates compared with those from eastern North America, a finding that was unrelated to differences in mutation load (ploidy). This study provided new insights into the adaptive evolution of a key indicator tree that provisions crucial ecosystem services across North America, but whose presence is steadily declining within its western distribution. We uncovered untapped adaptive potential across the species\u27 range which can form the basis for climate-resilient revegetation

Les interactions orales dans les groupes de révision rédactionnelle : une aide à la construction de connaissances diverses

INTRODUCTION Cet article fait état d’une recherche-action s’intéressant aux interactions orales permettant la construction des connaissances en langue française. L’outil didactique utilisé est le groupe de révision rédactionnelle. Nous avons mené notre étude dans deux milieux linguistiques différents au Canada francophone : l’un où les francophones sont majoritaires, le Québec, et l’autre où les francophones ne constituent que 33 % de la population, le Nouveau-Brunswick. Cette étude a été réa..