Analyse de l'implication de génie scotin dans le développement thymique

Les lymphocytes T sont essentiels aux fonctions du système immunitaire. Deux classes effectrices distinctes, les cellules T CD4 auxiliaires et les cellules T CD8 cytotoxiques, se développent dans le thymus. Les mécanismes de maturation des lymphocytes T dans cet organe se déroulent de façon très ordonnée et sont strictement régulés pour assurer l'homéostasie du système immunitaire. Dans le but de découvrir de nouvelles molécules impliquées dans ces processus de maturation, le groupe du Dr Steimie a effectué une étude transcriptomique sur des thymocytes de souris C57/BL6 en développement soit du stade DP immature au stade SP mature. Avec une approche de micropuces à ADN, plusieurs gènes ont été identifiés comme étant fortement modulés au cours des différentes étapes de maturation. Nous nous sommes intéressés à un transcrit nommé scotin qui est fortement modulé dans les cellules post-DP et qui a été associé à la sélection négative via nos analyses. L'expression de cette protéine dans le thymus est observée surtout chez les cellules semi-matures de type R3/R4 de la médulla. Le gène scotin possède 3 promoteurs internes qui permettent l'expression de 2 isoformes dans le thymus. Ceux-ci ont des fonctions différentes dans l'apoptose chez les cellules HeLa et leur localisation sub-cellulaire l'est aussi. L'expression de scotin1 et de scotin4 augmente avec la maturation des thymocytes, mais c'est scotin4 qu'on retrouve en majorité à toutes les étapes du développement. Des DP qu'on induit chimiquement avec un signal mimant celui fourni par le TCR lors de la sélection négative ne montrent pas d'augmentation de la synthèse de scotin . Cependant, des lignées de thymomes ayant des réponses pro- et anti-apoptotiques face à ce même stimulus montrent une expression préférentielle de scotin1 et scotin4 respectivement. Si on inhibe la production des transcrits communs de scotin via shRNA chez ces lignées de thymomes, on inverse leur réponse face à la stimulation au PMA/Ionomycin et le ratio scotin1/scotin4 est aussi inversé comparativement aux cellules mères. Ce dernier serait important pour le contrôle de la réponse apoptotique des thymomes. Nous croyons que les deux isoformes de scotin sont impliquées dans le développement thymique et ce, de façon indépendante l'une de l'autre

Ocular metrics for detecting attentional tunnelling

This paper focuses on ocular measurement to detect the human operator’s particular state of “attentional tunnelling” during a robot supervisory task. After a survey of the existing ocular metrics, an innovative fixation detection algorithm is proposed. Then the metrics derived from the ocular parameters calculated by the algorithm are tested in a human-robot experiment. Among the metrics calculated, 3 of them appear to be able to statisticaly discrimintate the operators who faced attentional tunnelling

The Impact of the Ontarian Minimum Wage on the Unemployment of Women and the Young in Ontario: A Note

The purpose of this research note is to apply to Ontario a methodology developed and applied by one of the authors (Cousineau 1990) to measure the impact of Quebec's minimum wage on the unemployment of women and the young. This is of interest for two reasons. First, it allows us to examine the robustness of the methodology used by Cousineau (1990); and second, it permits us to contribute to the debate now ongoing in Ontario as to the impacts of raising the minimum wage in the province. This is of some interest, given the paucity of information on these impacts. The paper is divided into three parts. In the first one, we briefly summarize the analytical framework used. In the second, we discuss the data and variables used. In the third, we present and analyze régression results for Ontario, compare them to those obtained for Québec and use them to examine the proposed increase in the minimum wage

Circulating cell-free nucleic acids of plasma in human aging, healthy aging and longevity: current state of knowledge

Circulating cell-free nucleic acids (ccfNAs) of plasma are a remarkable source of genetic, epigenetic and transcriptomic materials originating from different cells, tissues and organs of an individual. They have been increasingly studied over the past decade as they can carry several important pieces of information about the health status of an individual, which makes them biomarkers of choice for non-invasive diagnosis of numerous diseases and health conditions. However, few studies have investigated variations of plasma ccfNAs in healthy subjects, particularly in relation to aging, healthy aging and longevity, despite the great variability of these biological processes among individuals. Here, we reviewed several studies that focused on the analysis of circulating cell-free DNA (ccfDNA) and microRNAs (ccfmiRNAs) during aging and in the elderly, including some on exceptionally long-lived individuals, i.e., centenarians. After a brief overview of the types, origins and functions of plasma ccfNAs, we described the variations of both ccfDNA and ccfmiRNAs during aging as well as the identification of several potential ccfDNA-based and ccfmiRNA-based biomarkers of aging, healthy aging and/or longevity. We finally highlighted some prospects offered by ccfNAs for the understanding and improvement of healthy aging and longevity

Investigating Gene–Gene and Gene–Environment Interactions in the Association Between Overnutrition and Obesity-Related Phenotypes

Introduction: Animal studies suggested that NFKB1, IKBKB, and SOCS3 genes could be involved in the association between overnutrition and obesity. This study aims to investigate interactions involving these genes and macronutrient intakes affecting obesity-related phenotypes.Methods: We used a traditional statistical method, logistic regression, and compared it to alternative statistical method, multifactor dimensionality reduction (MDR) and penalized logistic regression (PLR), to better detect genes/environment interactions in the Toronto Nutrigenomics and Health Study (n = 1639) using dichotomized body mass index (BMI) and waist circumference as obesity-related phenotypes. Exposure variables included genotype on 54 single nucleotide polymorphisms (NFKB1: 18, IKBKB: 9, SOCS3: 27), macronutrient (carbohydrates, protein, fat) and alcohol intakes and ethno-cultural background.Results: After correction for multiple testing, no interaction was found using logistic regression. MDR identified interactions between SOCS3 rs6501199 and rs4969172, and IKBKB rs3747811 affecting BMI in the Caucasian population; SOCS3 rs6501199 and NFKB1 rs1609798 affecting WC in the Caucasian population; and SOCS3 rs4436839 and IKBKB rs3747811 affecting WC in the South Asian population. PLR found a main effect of SOCS3 rs12944581 on BMI among the South Asian population.Conclusion: While MDR and PLR had discordant results, some models support results from previous studies. These results emphasize the need to use alternative statistical methods to investigate high-order interactions and suggest that variants in the nutrient-responsive hypothalamic IKKB/NF-kB signaling pathway may be involved in obesity pathogenesis

On the interaction of acetone with electrophilic metallocavitands having extended cavities

We report the synthesis and characterization of tantalum–boronate trimetallic clusters of general formula {[Cp*Ta]3(μ2-RB(O)2)3(μ2-OH)(μ2-O)2(μ3-OH)} (R= 4-(C6H5)(C6H4) (Ta3-4Ph), 4-(C6H5O)(C6H4) (Ta3-4OPh), 4-(C7H7O)(C6H4) (Ta3-4OBn), 4-(C8H5)(C6H4) (Ta3-4PhEt), and 4-(C12H7)(C6H4) (Ta3-4Napht)). All complexes have been characterized by NMR spectroscopy and X-ray diffraction. The trimetallic species feature a large Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. ΔH° and ΔS° values for association of acetone with the complexes vary between −2.0 and −4.1 kcal·mol–1 and −3 and 2 cal·mol–1·K–1, respectively, showing weaker binding than smaller cavitands of the same type. The barrier for acetone exchange at equilibrium is similar for all complexes, and ΔH‡ values vary between 8.2 and 11.4 kcal·mol–1

Compte rendu a la classe des sciences mathématiques et physiques de l'Institut National dans sa séance du 11 messidor an 8 de la vente des laines et de l'accroissement du troupeau national de Rambouillet en l'an 8

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Bacillus subtilis Early Colonization of Arabidopsis thaliana Roots Involves Multiple Chemotaxis Receptors

ABSTRACT Colonization of plant roots by Bacillus subtilis is mutually beneficial to plants and bacteria. Plants can secrete up to 30% of their fixed carbon via root exudates, thereby feeding the bacteria, and in return the associated B. subtilis bacteria provide the plant with many growth-promoting traits. Formation of a biofilm on the root by matrix-producing B. subtilis is a well-established requirement for long-term colonization. However, we observed that cells start forming a biofilm only several hours after motile cells first settle on the plant. We also found that intact chemotaxis machinery is required for early root colonization by B. subtilis and for plant protection. Arabidopsis thaliana root exudates attract B. subtilis in vitro, an activity mediated by the two characterized chemoreceptors, McpB and McpC, as well as by the orphan receptor TlpC. Nonetheless, bacteria lacking these chemoreceptors are still able to colonize the root, suggesting that other chemoreceptors might also play a role in this process. These observations suggest that A. thaliana actively recruits B. subtilis through root-secreted molecules, and our results stress the important roles of B. subtilis chemoreceptors for efficient colonization of plants in natural environments. These results demonstrate a remarkable strategy adapted by beneficial rhizobacteria to utilize carbon-rich root exudates, which may facilitate rhizobacterial colonization and a mutualistic association with the host

Multifractal stationary random measures and multifractal random walks with log-infinitely divisible scaling laws

We define a large class of continuous time multifractal random measures and processes with arbitrary log-infinitely divisible exact or asymptotic scaling law. These processes generalize within a unified framework both the recently defined log-normal Multifractal Random Walk (MRW) [Bacry-Delour-Muzy] and the log-Poisson "product of cynlindrical pulses" [Barral-Mandelbrot]. Our construction is based on some ``continuous stochastic multiplication'' from coarse to fine scales that can be seen as a continuous interpolation of discrete multiplicative cascades. We prove the stochastic convergence of the defined processes and study their main statistical properties. The question of genericity (universality) of limit multifractal processes is addressed within this new framework. We finally provide some methods for numerical simulations and discuss some specific examples.Comment: 24 pages, 4 figure