Reconstitution of archaeal H/ACA small ribonucleoprotein complexes active in pseudouridylation

Pseudouridine (Ψ) are frequently modified residues in RNA. In Eukarya, their formation is catalyzed by enzymes or by ribonucleoprotein complexes (RNPs) containing H/ACA snoRNAs. H/ACA sRNA and putative ORFs for H/ACA sRNP proteins (L7Ae, aCBF5, aNOP10 and aGAR1) were found in Archaea. Here, by using Pyrococcus abyssi recombinant proteins and an in vitro transcribed P.abyssi H/ACA sRNA, we obtained the first complete in vitro reconstitution of an active H/ACA RNP. Both L7Ae and the aCBF5 RNA:Ψ synthase bind directly the sRNA; aCBF5 also interacts directly and independently with aNOP10 and aGAR1. Presence of aCBF5, aNOP10 and a U residue at the pseudouridylation site in the target RNA are required for RNA target recruitment. In agreement, we found that the aCBF5–aNOP10 pair is the minimal set of proteins needed for the formation of a particle active for pseudouridylation. However, particles more efficient in targeted pseudouridylation can be formed with the addition of proteins L7Ae and/or aGAR1. Although necessary for optimal activity, the conserved ACA motif in the sRNA was found to be not essential

L’analyse politique de l’action publique : confrontation des approches, des concepts et des méthodes

Ce numéro spécial s’inscrit dans la suite d’une série de dossiers que la Revue française de science politique a consacré, depuis une quinzaine d’années, à l’analyse des politiques publiques. Au travers de nouvelles interrogations sur les approches et les méthodes en cours au sein de ce domaine de recherche, il permet d’en suivre les profondes évolutions, en France notamment, où ce domaine s’est autonomisé par rapport au droit et aux sciences du gouvernement, qui reposaient sur une démarche relativement descriptive et séquentielle du travail gouvernemental. [Premier paragraphe

Representation of Objects in Space by Two Classes of Hippocampal Pyramidal Cells

Humans can recognize and navigate in a room when its contents have been rearranged. Rats also adapt rapidly to movements of objects in a familiar environment. We therefore set out to investigate the neural machinery that underlies this capacity by further investigating the place cell–based map of the surroundings found in the rat hippocampus. We recorded from single CA1 pyramidal cells as rats foraged for food in a cylindrical arena (the room) containing a tall barrier (the furniture). Our main finding is a new class of cells that signal proximity to the barrier. If the barrier is fixed in position, these cells appear to be ordinary place cells. When, however, the barrier is moved, their activity moves equally and thereby conveys information about the barrier's position relative to the arena. When the barrier is removed, such cells stop firing, further suggesting they represent the barrier. Finally, if the barrier is put into a different arena where place cell activity is changed beyond recognition (“remapping”), these cells continue to discharge at the barrier. We also saw, in addition to barrier cells and place cells, a small number of cells whose activity seemed to require the barrier to be in a specific place in the environment. We conclude that barrier cells represent the location of the barrier in an environment-specific, place cell framework. The combined place + barrier cell activity thus mimics the current arrangement of the environment in an unexpectedly realistic fashion

Medidas morfométricas e correlações fenotípicas de tilápia Gift submetidas a seleção individual

O objetivo deste estudo foi avaliar o efeito da seleção individual para peso corporal nas medidas morfométricas de tilápia-do-nilo, linhagem GIFT-Epagri, e determinar as correlações destas medidas com o peso do corpo. Foram utilizados 325 machos e 272 fêmeas, derivados de sete diferentes populações do programa de melhoramento. De cada indivíduo foram avaliados os seguintes parâmetros: peso corporal (PC), comprimento total (CT), comprimento padrão (CP), comprimento do tronco (CTr), comprimento da cabeça (CC), altura corporal (AC) e largura corporal (LC). Posteriormente, foram determinadas as seguintes relações: fator de condição de Fulton (FC), CC/CP, AC/CP, LC/CP e CTr/CP. Os indivíduos selecionados para peso corporal das diferentes populações apresentaram maior FC e AC/CP, em relação aos indivíduos não selecionados. Além disso, todas as correlações entre as variáveis analisadas foram altas (acima de 0,70), indicando que na seleção dos indivíduos com maior peso há boa possibilidade de haver ganhos indiretos para outras características desejáveis. Abstract - This study aimed to evaluate the effect of individual selection for body weight on morphometric characteristics of the Nile tilapia, Gift-Epagri strain, and as well as to determine the phenotypic correlations of these measurements. We used 325 males and 272 females derived from seven different populations of the breeding program. The following morphometric characteristics were measured: body weight (BW), total length (TL), standard length (SL), corrected length (CL), head length (HL), body height (BH) and body width (BW). Thereafter, the data were used to determine the following ratios: Fulton condition factor (FC), HL/SL, BH/SL, BW/SL and CL/SL. Fish selected for body weight showed greater FC and BH/SL compared to unselected fish. In addition, all correlations between variables were high (above 0.70), indicating that the selection of individuals with higher body weight may provide indirect gains in other desirable characteristics.O objetivo deste estudo foi avaliar o efeito da seleção individual para peso corporal nas medidas morfométricas de tilápia-do-nilo, linhagem GIFT-Epagri, e determinar as correlações destas medidas com o peso do corpo. Foram utilizados 325 machos e 272 fêmeas, derivados de sete diferentes populações do programa de melhoramento. De cada indivíduo foram avaliados os seguintes parâmetros: peso corporal (PC), comprimento total (CT), comprimento padrão (CP), comprimento do tronco (CTr), comprimento da cabeça (CC), altura corporal (AC) e largura corporal (LC). Posteriormente, foram determinadas as seguintes relações: fator de condição de Fulton (FC), CC/CP, AC/CP, LC/CP e CTr/CP. Os indivíduos selecionados para peso corporal das diferentes populações apresentaram maior FC e AC/CP, em relação aos indivíduos não selecionados. Além disso, todas as correlações entre as variáveis analisadas foram altas (acima de 0,70), indicando que na seleção dos indivíduos com maior peso há boa possibilidade de haver ganhos indiretos para outras características desejáveis.

0383 : In vitro 3D model of in vitro angiogenesis using human endothelial cells and pericytes

Human tissue is three-dimensional, and requires convective transport of nutrients and waste through capillary networks to meet metabolic demands Angiogenesis is the formation of new blood vessels from the existing vasculature. It is a multi-step process that include: degradation of the basement membrane, proliferation and migration (sprouting) of endothelial cells (EC) into the extracellular matrix, alignment of EC into cords, branching, lumen formation, anastomosis, and formation of a new basement membrane. The literatture in 3D in vitro models using endothelial cells is wide, using various types of EC (essentially Human Umbilical Vein Endothelial Cells), but blood vessels are composed of two interacting cells types: endothelial cells form the inner of the vessel wall, and mural cells that wrap the first ones. Pericytes are the mural cells of microvessels. They serve as scaffolding, and they communicate with endothelial cells by direct physical contacts and paracrine signaling pathways. Presently, there are no three-dimensional in vitro models of 3D Matrices which contain human pericyte-coated capillaries. Therefore, we aim at including pericytes in a 3D vascular morphogenesis assay in order to create a 3D in vitro model more close to physiologic conditions. We’ll show and discuss our first analyzes and results, the goal of which is to provide new in vitro tools in order to better understand vascular biology, for later studies of endothelial cells-pericytes interactions, extracellular matrix-pericytes interactions, and eventually, further elucidate the role of pericytes in the microvasculature