ETHYLENE-INSENSITIVE5 Encodes a 5\u27→3\u27 Exoribonuclease Required for Regulation of the EIN3-Targeting F-Box Proteins EDF1⁄2

Ethylene is a gaseous plant growth regulator that controls a multitude of developmental and stress responses. Recently, the levels of Arabidopsis EIN3 protein, a key transcription factor mediating ethylene-regulated gene expression, have been demonstrated to increase in response to the presence of ethylene gas. Furthermore, in the absence of ethylene, EIN3 is quickly degraded through a ubiquitin/proteasome pathway mediated by two F-box proteins, EBF1 and EBF2. Here we report the identification of ETHYLENE-INSENSITIVE5 as the 5′→3′ exoribonuclease XRN4. Specifically, we demonstrate that EIN5 is a component of the ethylene signal transduction cascade acting downstream of CTR1 that is required for ethylene-mediated gene expression changes. Furthermore, we find that the ethylene insensitivity of ein5 mutant plants is a consequence of the over-accumulation of EBF1 and EBF2 mRNAs resulting in the under-accumulation of EIN3 even in the presence of ethylene gas. Together, our results suggest that the role of EIN5 in ethylene perception is to antagonize the negative feedback regulation on EIN3 by promoting EBF1 and EBF2 mRNA decay, which consequently allows the accumulation of EIN3 protein to trigger the ethylene response

The Telomerase Reverse Transcriptase Subunit from the Dimorphic Fungus Ustilago maydis

In this study, we investigated the reverse transcriptase subunit of telomerase in the dimorphic fungus Ustilago maydis. This protein (Trt1) contains 1371 amino acids and all of the characteristic TERT motifs. Mutants created by disrupting trt1 had senescent traits, such as delayed growth, low replicative potential, and reduced survival, that were reminiscent of the traits observed in est2 budding yeast mutants. Telomerase activity was observed in wild-type fungus sporidia but not those of the disruption mutant. The introduction of a self-replicating plasmid expressing Trt1 into the mutant strain restored growth proficiency and replicative potential. Analyses of trt1 crosses in planta suggested that Trt1 is necessary for teliospore formation in homozygous disrupted diploids and that telomerase is haploinsufficient in heterozygous diploids. Additionally, terminal restriction fragment analysis in the progeny hinted at alternative survival mechanisms similar to those of budding yeast

Correção cirúrgica da origem anômala de artéria pulmonar direita em aorta ascendente

A origem anômala da artéria pulmonar direita em aorta ascendente é uma malformação congênita rara. Descrevemos o caso de uma criança submetida à correção cirúrgica com anastomose direta entre a artéria pulmonar direita e o tronco pulmonar. Após 18 meses a paciente permanece assintomática sem apresentar estenose residual significativa na angioressonância

Sistema de comunicación satelital

Trabajo propuesto para el estudio de las comunicaciones satelitales y su aplicación a la recepción doméstica de señales de televisión no codificadas. Comprende desde el estudio para la instalación del receptor y la antena hasta los pasos para dicha operación, además las bases teóricas de los diferentes componentes.GuayaquilIngeniero en Electricidad Especialización Electrónic

De l'aspect du temps, représentation et expression du temps passé en anglais et en français (étude contrastive dans une perspective traductologique)

Cette étude est fondamentalement une approche linguistique des problèmes de traduction liés au prétérit et à l imparfait en contexte spécifique. Elle se compose de trois grandes parties. La première s intéresse à la distinction entre aspect lexical et aspect grammatical. Cette distinction se fonde essentiellement sur la définition que donne G. Guillaume de la lexigénèse. La deuxième partie analyse le signifé de puissance de l imparfait et du prétérit ainsi que leurs effets de sens respectifs. Dans la troisième et dernière partie sont introduits quatre concepts clefs visant à justifier la traduction du prétérit simple par l imparfait ou le passé simple, ceux de perfectivité verticale, horizontale, intégrale et transitive. Sont également répertoriés plusieurs critères favorisant l emploi de la forme perfective et imperfective du prétérit, tels que l image temporelle du verbe, le concept philosophique de esse est percipi / percipi est esse, le principe de la deixis ad occulos, etc. Cette étude peut être enfin globalement considérée comme une réflexion sur le principe d orthonymie dans le processus de traduction.This study is basically a linguistic approach to the translation of the English preterite and the French imparfait, primarily in a specific context. It falls into three major parts. The first one focuses on the distinction between lexical and grammatical aspect. This distinction is mainly based on G. Guillaume s definition of the concept of lexigenesis. The second part analyses the potential significate of the imparfait and of the preterit and their related sense effects. In the last and third part, four key concepts are introduced to account for the translation of the simple past into either the imparfait or the passé simple, those of vertical, horizontal, integral and transitive perfectivity. Various criteria are also listed favouring the use of the perfective or the imperfective form of the preterit, such as the temporal contour of the verb, the philosophical concept of esse est percipi / percipi est esse, the deixis ad occulos principle, etc. Lastly, this study can be considered as an overall reflection on the principle of orthonymy underlying the translating process at large.TOULON-BU Centrale (830622101) / SudocSudocFranceF

Response of Adsorbed Polyelectrolyte Monolayers to Changes in Solution Composition

Reflectometry and quartz crystal microbalance are used to study the response of adsorbed polyelectrolyte monolayers to solutions of variable composition. These techniques respectively yield the dry and wet masses of the adsorbed layer, and by combing these results, one obtains the water content and the thickness of the polyelectrolyte films. The systems investigated are films of adsorbed poly(allyl amine) (PAH) and poly-l-lysine (PLL) on silica and films of poly(styrene sulfonate) (PSS) on amino-functionalized silica. When such films are adsorbed from concentrated polyelectrolyte solutions containing high levels of salt, they are found to swell reversibly up to a factor of 2 when incubated in solutions of low salt. This swelling is attributed to the strengthening of repulsive electrostatic interactions between the adsorbed polyelectrolyte chains. PAH films may also swell upon decrease of pH, and collapse upon a pH increase. This transition shows a marked hysteresis and can be rationalized by the competition of electrostatic repulsions between the chains and their attraction to the surface. The presently observed swelling phenomena are caused by a collective process driven by the electrostatic repulsion between the densely adsorbed polyelectrolyte chains. Such responsive layers are only obtained by adsorption from high polyelectrolyte and salt concentrations. Layers absorbed at low polyelectrolyte and salt concentrations show only minor swelling effects, since the adsorbed polyelectrolytes layers are dilute and the adsorbed polyelectrolyte chains interact only weakly