6 research outputs found
Human T-Cell Leukemia Virus Type 1 Tax Protein Down-Regulates Pre-T-Cell Receptor Alpha Gene Transcription in Human Immature Thymocytes
The human pre-T-cell receptor alpha (TCRα; pTα) gene encodes a polypeptide which associates with the TCRÎČ chain and CD3 molecules to form the pre-TCR complex. The surface expression of the pre-TCR is pTα dependent, and signaling through this complex triggers an early αÎČ T-cell developmental checkpoint inside the thymus, known as ÎČ-selection. E2A transcription factors, which are involved at multiple stages of T-cell development, regulate the transcription of the pTα gene. Here we show that the regulatory protein Tax of the human T-cell leukemia virus type 1 (HTLV-1) efficiently suppresses the E47-mediated activation of the pTα promoter. Furthermore, we report that in Tax lentivirally transduced human MOLT-4 T cells, which constitutively express the pTα gene, the amount of pTα transcripts decreases. Such a decrease is not observed in MOLT-4 cells transduced by a vector encoding the Tax mutant K88A, which is unable to interact with p300. These data underline that Tax inhibits pTα transcription by recruiting this coactivator. Finally, we show that the expression of Tax in human immature thymocytes results in a decrease of pTα gene transcription but does not modify the level of E47 transcripts. These observations indicate that Tax, by silencing E proteins, down-regulates pTα gene transcription during early thymocyte development. They further provide evidence that Tax can interfere with an important checkpoint during T-cell differentiation in the thymus
Estimation des pertes Ă la rĂ©colte du colza dâhiver (Brassica napus) dans des conditions variĂ©es
Oilseed rape seed loss during harvest can cause subsequent unwanted gene flow and thus give raise to management difficulties in order to keep segmented different productions. Furthermore, seed loss reduces benefits of producers. This loss was evaluated in different conditions and trials carried out in three French regions from 2002 to 2004. Seed loss was divided into three categories : before harvest, under the cutter bar and behind the combine harvester. Total loss represented on average 8,2 % of the harvest for grain water content under 12 %. But this figure does not take an important variability into account. Indeed, an advanced cutter bar could reduce loss by 80 % and grain humidity at harvest plays an important part in the total loss level and its distribution. Before harvest low grain water content could make seed loss more sensitive to climatic events. Under the cutter bar, seed loss is inversely proportional to grain water content. On the contrary, it increases with grain water content behind the combine, due to loss in green siliquae. These studies can help improving advice to producers and contribute to improve gene flow models
Le post-humain et les enjeux du sujet
La publication de ces textes sâinscrit dans le prolongement dâune journĂ©e dâĂ©tudes organisĂ©e en mai 2009 Ă lâuniversitĂ© de Toulouse-Le Mirail dans le cadre du Laboratoire de Recherches en Audiovisuel (LARA), qui a regroupĂ© plasticiens, philosophes, et psychanalystes. Cette journĂ©e avait pour objectif de sâinterroger sur un concept rĂ©current qui traverse aussi bien le champ de lâart, que celui de la philosophie, voire celui de la psychanalyse, sans parler des enjeux politiques quâil sous-tend, la question du post-humain
Premiers cris, premiĂšres nourritures
Cet ouvrage offre une mise en perspective des pratiques dâallaitement et de sevrage des nourrissons et des jeunes enfants, de la PrĂ©histoire Ă nos jours. Plus quâune histoire de lâallaitement, il dresse un bilan des savoirs les plus actuels autour de ces pratiques, depuis les premiĂšres minutes de vie jusquâĂ lâabandon dĂ©finitif du lait maternel. Un moment unique, un regard croisĂ© sur les modes dâalimentation des tout-petits et leurs dĂ©terminants, cette thĂ©matique, qui implique tant les sciences humaines et sociales que les sciences mĂ©dicales, est abordĂ©e dans une perspective diachronique, pluridisciplinaire et internationale. Les contributions rĂ©unies dans cet ouvrage vont au-delĂ des connaissances dĂ©jĂ produites par les historiens. Sâappuyant sur dâautres sources documentaires, comme celles contenues dans les milliers de squelettes humains issus des fouilles archĂ©ologiques, et les techniques dâanalyse du contenu chimique des ossements, il est dĂ©sormais possible dâexplorer le temps long, et de nuancer parfois les informations fournies par les textes anciens. Le large panorama ici retracĂ© permet de conclure quâau-delĂ des normes imposĂ©es par le discours mĂ©dical ou militant, lâallaitement maternel nâa jamais Ă©tĂ© le mode dâalimentation exclusif des nourrissons. De tout temps et sous toutes les latitudes, les comportements dâallaitement ont Ă©tĂ© modelĂ©s par des facteurs physiologiques, psychologiques, familiaux, dâordre social et Ă©conomique au « sein » desquels les politiques de santĂ© ont Ă©galement tentĂ© de sâimposer