Le rôle de la MAPK non-conventionnelle ERK3 dans le développement thymique

Les premières cellules progénitrices lympho-myéloïdes (LMPP) entrent dans le thymus et commencent leur processus de différenciation au stade double négatif (DN, CD4-CD8-). Après un réarrangement fonctionnel de la chaine bêta de leur récepteur des cellules T (RCT), les cellules reçoivent des signaux de différenciation, de prolifération, de survie et de sélection et passent au stade double positif (DP, CD4+CD8+). Ensuite, la chaine alpha du RCT est réarrangée et testée via les sélections positive et négative. Si le RCT reçoit un signal ni trop fort, ni trop faible, les cellules passent au stade simple positif où elles exprimeront soit la molécule CD4 ou CD8. ERK3, une MAPK non-conventionnelle, joue un rôle important dans le développement thymique. Des études précédentes ont démontré qu’une déficience en ERK3 diminue de 50 % la cellularité thymique et de 75% le nombre de cellules simples positives CD4 (CD4SP). Nous avons posé comme hypothèses qu’il y a une augmentation de l’apoptose chez les thymocytes DP de souris Erk3-/- et que cette déficience chez les thymocytes DP affecterait la sélection positive des cellules DP, réduisant ainsi le nombre de thymocytes CD4SP. Afin de vérifier la première hypothèse, nous avons regardé les niveaux d’apoptose grâce à la cytométrie en flux et par immunohistochimie. Dans les deux cas, nous étions incapables de détecter une différence du niveau d’apoptose chez les thymocytes DP entre les souris Erk3+/+ et Erk3-/-. Ensuite, nous nous sommes posés la question suivante : La demi-vie des thymocytes DP Erk3-/- était-elle plus courte que le type sauvage? La demi-vie des thymocytes DP a été mesurée à l’aide de l’étude des réarrangements secondaires de la chaine alpha du RCT par PCR semi-quantitatif et à l’aide de cultures de thymus fœtaux. En effet, ERK3 semble important pour prolonger la demi-vie des thymocytes DP. Ensuite, nous avons utilisé des marqueurs cellulaires différentiels (CD69, CD5 et RCT) pour regarder si les thymocytes DP sont capables de passer la sélection positive. En effet, il y a moins de thymocytes DP Erk3-/- qui sont CD69fort, CD5fort et RCTfort. Finalement, nous voulons savoir si les fonctions de ERK3 passent par MK5, son seul partenaire d’interaction connu à ce jour. Après la caractérisation du thymus de la souris Mk5-/-, nous observons que seulement la réduction du nombre de thymocytes CD4SP est identique à celle des thymocytes CD4SP de la souris Erk3-/-. En conclusion, ces résultats révèlent des fonctions importantes pour la molécule ERK3 lors du processus de sélection positive, le maintient de la demi-vie des thymocytes DP et lors de la régulation de développement thymique de manière MK5-dépendante et -indépendante.Early thymic progenitor cells (ETP) enter the thymus and begin their differentiation process at the double negative (DN) stage, having no CD4 and CD8 expression. After a functional rearrangement of the beta chain of the T-cell receptor (TCR), the cells receive differentiation, proliferation, survival, and selection signals and pass to the double positive (DP) stage and acquire the expression of CD4 and CD8 molecules. Then, the TCR alpha chain is rearranged and the fully composed TCR is tested through positive and negative selection. If the TCR receives a signal that is just right (not too strong or too weak), the cells pass to the single-positive stage by acquiring either the CD4 or CD8 molecule. ERK3, an unconventional MAPK, plays an important role in thymic development. Previous studies have shown that a deficiency in ERK3 decreases by 50% the total thymic cellularity and by 75% the number of CD4 single- positive cells (CD4SP). We hypothesized that there is an increase in apoptosis in DP thymocytes of Erk3-/- mice for and that this deficiency would affect the positive selection of DP cells, resulting in a reduced number of CD4SP. To test the first hypothesis, we looked at apoptosis levels by flow cytometry and immunohistochemistry. In both cases, we were unable to detect a difference in the level of apoptosis in DP thymocytes from Erk3+/+ and Erk3-/- mice. We then made a second assumption, that the half-life of Erk3-/- DP thymocytes for was shorter, which was measured by secondary rearrangements of the RCT alpha chain by semi-quantitative PCR and cultures of fetal thymi. Indeed, ERK3 seems important to extend the half- life of DP thymocytes. Next, we used differential cell markers (CD69, CD5, and TCR) to see if the DP thymocytes are able to pass positive selection. Indeed, there are less DP thymocytes Erk3-/- that are CD69hi, CD5hi, and TCRhi. Finally, we wanted to know whether the functions of ERK3 passes through MK5, its only interacting partner known to date. After characterization of the thymus of Mk5-/- mice, we observe that only the reduction of CD4SP thymocytes is identical to that of CD4SP thymocytes of Erk3-/-mice. In conclusion, these results reveal important functions for the molecule ERK3 for maintaining the half-life of DP thymocytes, for the process of positive selection and for regulating T-cell development in a MK5-dependent and - independent manner

Investigation de la spécificité nucléotidique de l’hélicase DHX36 lors du déroulement de structures d’ARN G-quadruplex.

La déstabilisation des structures G-quadruplex au niveau des acides nucléiques a des répercussions physiologiques importantes. L’accentuation des connaissances concernant les processus cellulaires associés au métabolisme des structures des G4 est primordiale. Une panoplie d’hélicases à G4 est impliquée dans le métabolisme des structures G4, notamment l’hélicase humaine DHX36. Il a été déterminé au préalable par certains groupes de recherche que l’hélicase DHX36 se lie à son substrat l’ARN G4 et utilise des nucléosides triphosphates afin de catalyser le dépliement de la structure G-quadruplex. Toutefois, l’interaction avec l’ARN G4 a été sommairement caractérisée et la spécificité nucléotidique n’a toujours pas été évaluée. Ainsi, nous avons décidé d’approfondir les connaissances du mécanisme de dépliement de la structure du G4 d’ARN par l’hélicase DHX36. Notamment, en évaluant la thermodynamique de l’interaction entre l’hélicase et l’ARN G4 afin de révéler particulièrement l’efficacité de liaison mais également en évaluant la spécificité nucléotidique de l’hélicase DHX36 afin d’effectuer le dépliement de l’ARN G4. La combinaison des analogues de nucléotides et le modèle structural permettent de révéler les caractéristiques structurales et fonctionnelles de l’interaction entre l’hélicase humaine DHX36 et l’ATP. Nos analyses permettent de constater que l’enzyme DHX36 est en mesure d’utiliser autant l’ATP que GTP afin de dérouler les structures G4 d’ARN ayant, par contre, une spécificité accrue pour la molécule d’ATP

Validation of an open source, remote web‐based eye‐tracking method (WebGazer) for research in early childhood

Measuring eye movements remotely via the participant's webcam promises to be an attractive methodological addition to in-person eye-tracking in the lab. However, there is a lack of systematic research comparing remote web-based eye-tracking with in-lab eye-tracking in young children. We report a multi-lab study that compared these two measures in an anticipatory looking task with toddlers using WebGazer.js and jsPsych. Results of our remotely tested sample of 18-27-month-old toddlers (N = 125) revealed that web-based eye-tracking successfully captured goal-based action predictions, although the proportion of the goal-directed anticipatory looking was lower compared to the in-lab sample (N = 70). As expected, attrition rate was substantially higher in the web-based (42%) than the in-lab sample (10%). Excluding trials based on visual inspection of the match of time-locked gaze coordinates and the participant's webcam video overlayed on the stimuli was an important preprocessing step to reduce noise in the data. We discuss the use of this remote web-based method in comparison with other current methodological innovations. Our study demonstrates that remote web-based eye-tracking can be a useful tool for testing toddlers, facilitating recruitment of larger and more diverse samples; a caveat to consider is the larger drop-out rate

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia