39 research outputs found
Mécanisme de régulation des gènes par le récepteur des oestrogènes alpha : fonction des éléments de réponse des oestrogènes (ERE) en tant qu'enhancers distaux
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal
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Examination of the Aggregate Scoring Method in a Judgment Concordance Test
The use of the aggregate scoring method for scoring concordance tests requires the weighting of test items to be derived from the performance of a group of experts who take the test under the same conditions as the examinees. However, the average score of experts constituting the reference panel remains a critical issue in the use of these tests. This study aims to examine the distribution of panelists’ scores on the judgment concordance test (JCT) using the aggregate scoring method. A test composed of 32 items was developed and completed by 14 experts. The mean scores of the experts were calculated based on whether their choices of response categories for the 32 JCT items were included or excluded. Descriptive statistics were conducted. The mean scores of the experts showed a difference of 5.76%, depending on the approach used. The approach that excludes the experts’ response category choices was found to be more penalizing (76.16%±8.9) than the method including their own choices (81.92%±8.1). It is recommended that researchers make their computational approaches explicit in addition to outlining the distribution of expert results retained for the purpose of determining scores in the concordance tests. Further research is required to refine our understanding of the quality of score-setting in this type of test
Rational design of an estrogen receptor mutant with altered DNA-binding specificity
Although artificial C2-H2 zinc fingers can be designed to recognize specific DNA sequences, it remains unclear to which extent nuclear receptor C4 zinc fingers can be tailored to bind novel DNA elements. Steroid receptors bind as dimers to palindromic response elements differing in the two central base pairs of repeated motifs. Predictions based on one amino acid—one base-pair relationships may not apply to estrogen receptors (ERs), which recognize the two central base pairs of estrogen response elements (EREs) via two charged amino acids, each contacting two bases on opposite DNA strands. Mutagenesis of these residues, E203 and K210 in ERα, indicated that both contribute to ERE binding. Removal of the electric charge and steric constraints associated with K210 was required for full loss of parental DNA-binding specificity and recognition of novel sequences by E203 mutants. Although some of the new binding profiles did not match predictions, the double mutation E203R-K210A generated as predicted a mutant ER that was transcriptionally active on palindromes of PuGCTCA motifs, but not on consensus EREs. This study demonstrates the feasibility of designing C4 zinc finger mutants with novel DNA-binding specificity, but also uncovers limitations of this approach
Diagnose écologique du lac Lâche
Une diagnose écologique a été réalisée, en septembre 2005, sur le Lac Lâche de la Réserve faunique Duchénier, dans la MRC Rimouski-Neignette. Les objectifs de cette étude étaient de déterminer l’état trophique du plan d’eau ainsi que de connaître le potentiel salmonicole. Plusieurs paramètres ont donc été mesurés tels que la physico-chimie de l’eau, la bathymétrie et la morphométrie du lac. Aussi, des inventaires sur les sites de frais et la communauté ichthyenne ont été réalisés. Selon la superficie de la zone 0 à 6 mètres couvrant 61% du lac et représentant l’habitat préférentiel de l’omble de fontaine (Salvelinus fontinalis), le lac semble être un habitat adéquat. Sur le plan de la physico-chimie de l’eau, le plan d’eau bien aux exigences de l’omble de fontaine. Le principal problème rencontré au lac Lâche semble être le manque de frayères de qualité. Des endroits, comme le pourtour de l’île et le tributaire du lac Croche, ont été identifiés comme des sites potentiels où des aménagements pourraient être réalisés pour améliorer la qualité des frayères. De plus, l’omble de fontaine vie en sympatrie avec sept espèces de cyprins, ce qui cause de la compétition pour les ressources alimentaires. Des recommandations sont suggérées pour améliorer le potentiel salmonicole