93 research outputs found

    Prolactin induces apoptosis of lactotropes in female rodents

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    Anterior pituitary cell turnover occurring during female sexual cycle is a poorly understood process that involves complex regulation of cell proliferation and apoptosis by multiple hormones. In rats, the prolactin (PRL) surge that occurs at proestrus coincides with the highest apoptotic rate. Since anterior pituitary cells express the prolactin receptor (PRLR), we aimed to address the actual role of PRL in the regulation of pituitary cell turnover in cycling females. We showed that acute hyperprolactinemia induced in ovariectomized rats using PRL injection or dopamine antagonist treatment rapidly increased apoptosis and decreased proliferation specifically of PRL producing cells (lactotropes), suggesting a direct regulation of these cell responses by PRL. To demonstrate that apoptosis naturally occurring at proestrus was regulated by transient elevation of endogenous PRL levels, we used PRLR-deficient female mice (PRLRKO) in which PRL signaling is totally abolished. According to our hypothesis, no increase in lactotrope apoptotic rate was observed at proestrus, which likely contributes to pituitary tumorigenesis observed in these animals. To decipher the molecular mechanisms underlying PRL effects, we explored the isoform-specific pattern of PRLR expression in cycling wild type females. This analysis revealed dramatic changes of long versus short PRLR ratio during the estrous cycle, which is particularly relevant since these isoforms exhibit distinct signaling properties. This pattern was markedly altered in a model of chronic PRLR signaling blockade involving transgenic mice expressing a pure PRLR antagonist (TGΔ1–9-G129R-hPRL), providing evidence that PRL regulates the expression of its own receptor in an isoform-specific manner. Taken together, these results demonstrate that i) the PRL surge occurring during proestrus is a major proapoptotic signal for lactotropes, and ii) partial or total deficiencies in PRLR signaling in the anterior pituitary may result in pituitary hyperplasia and eventual prolactinoma development, as observed in TGΔ1–9-G129R-hPRL and PRLRKO mice, respectively.Fil: Ferraris, Maria Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina; Argentina. Universidad de Buenos Aires; ArgentinaFil: Zarate, Sandra Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina; Argentina. Universidad de Buenos Aires; ArgentinaFil: Jaita, Gabriela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina; Argentina. Universidad de Buenos Aires; ArgentinaFil: Boutillon, Florencia. Universite Paris Sud; FranciaFil: Bernadet, Marie. Universite Paris Descartes; FranciaFil: Auffret, Julien. Universite Paris Sud; FranciaFil: Seilicovich, Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina; Argentina. Universidad de Buenos Aires; ArgentinaFil: Binart, Nadine. Universite Paris Sud; FranciaFil: Goffin, Vincent. Universite Paris Descartes; FranciaFil: Pisera, Daniel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina; Argentina. Universidad de Buenos Aires; Argentin

    Pyroséquençage pour le développement d'EST et de SNP aviaires

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    Le but du programme est de combler les déficits en marqueurs observés pour trois espèces aviaires : la caille, le canard et la poule. La stratégie choisie est l'obtention, à partir de plusieurs individus de lignées d'intérêt, de SNP (Single Nucleotide Polymorphism, polymorphisme d'un nucléotide) par une nouvelle technologie de séquençage à haut débit (séquenceur 454 GS-FLX, Roche). Nous séquençons des représentations réduites du génome, en sélectionnant d'une part des fragments de restriction d'ADN génomique - les mêmes chez tous les individus - et d'autre part les transcrits qui représentent globalement la partie du génome correspondant aux gènes exprimés. Ces expérimentations sont réalisées à partir d'échantillons d'ADN ou d'ARN issus d'individus de lignées à l'origine de croisements existants, pour chacune des trois espèces. Les données générées par plusieurs "runs" de séquence seront traitées in silico : contigage à haut débit, recherche de SNP, comparaison avec les banques de séquences connues...En plus de l'intérêt que représente la production d'un très grand nombre de SNP nouveaux, cette technologie devrait permettre de mieux séquencer les régions riches en (G+C) correspondant aux plus petits des microchromosomes pour lesquels il n'y a pas de séquence chez la poule. La comparaison des séquences des transcrits obtenues chez la caille et le canard avec la séquence du génome de la poule permettra d'établir une "cartographie virtuelle" des SNP obtenus, grâce à la grande conservation de synténie existant entre ces trois espèces

    Analyse de l’écriture d’Annie Ernaux dans La Place et La Honte : Entre littérature et sociologie

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    The purpose of this study is to analyze the writing of Annie Ernaux in two early texts LaPlace and La Honte. We will explain the notion of “écriture plate” (neutral writing) firstdefined by Roland Barthes and we will examine Ernaux’s narrative approach regarding thisconcept. We will also review the place and the use of the sociological in the two novels,focusing on the intertextuality between Ernaux’s and Bourdieu’s work. Our theoreticalbackground will be based on Barthes’ literary critic in Writing Degree Zero and onBourdieu’s general studies about class distinction and reproduction of social structures

    Ambiguity in feminity and masculinity. : A study of L'Amant de la Chine du Nord by Marguerite Duras

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    The purpose of this study is to explore the manifestations and representations of masculinity and feminity in two novels of Marguerite Duras from a gender studies perspective. We will first review the traditional place of masculine and feminine stereotypes in the phallocentric order, basing our research on Bourdieu’s and Badinter’s work about the role of men and women in our society. Regarding the topic of sexual identity, our theoretical background will include feminist theories as Judith Butler’s gender performativity concept as well as Luce Irigaray’s notion of mimesis. The philosophy part can also give important clues for the interpretation of both male and female sentimental and sexual behavior: the work of the philosopher Michel Onfray, in particular his theory called "solar erotic", will help us to reveal the characteristics of Duras’ erotic writing. The results of our analysis show that both characters in the two novels present an ambiguous sexual identity: they seem to hesitate between the social obligation relative to their gender and the need of acting according to their own nature (androgyny of the Chinese). Our analysis shows the possibility of a deconstruction of the gender as well as a tendency to what Butler calls the subversion of identity. The exploration of Duras’ erotic writing seems to confirm those results, demonstrating the power of feminine desire and sexual pleasure in opposition to masculine sentimental pain and fragility

    Effect of lipid content on oxidation susceptibility of duck meat

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    International audienceLipid content in duck meat can show a very large variation. It influences the nutritional and sensory attributes of the meat and perhaps it influences meat susceptibility to oxidation during cold storage of fresh or processed meat. By combining the duck genotype (Muscovy duck, Pekin duck and mule) and the nutritional level (ad libitum or overfed) we were able to obtain duck fillets exhibiting a large variation in lipid content and to distribute them into 3 classes (2.0 to 3.5%, 4.0 to 5.5% and 5.9 to 7.9% fat). Storage at + 4 degrees C or -20 degrees C of raw meat or at + 4 degrees C of dry-cured fillets did neither affect the colour and fatty acid composition of the meat nor its susceptibility to lipid or protein oxidation

    Lyon, nœud de communication européen

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    Expertise réalisée pour le compte de l'Agence d'Urbanisme de la Communauté Urbaine de Lyon sous la responsabilité scientifique de François PlassardLes problèmes liés à la position de Lyon, et plus particulièrement de Satolas, comme un noeud de transport européen, sont particulièrement complexes, au point qu'il ne peut pas en être fait une analyse complète selon un plan linéaire. C'est pourquoi nous avons préférer privilégier plusieurs thèmes qui servent de point de départ pour l'analyse de ces problème: - la place de Satolas dans le réseau aérien - la desserte de Satolas par les trains régionaux et TGV - le rôle de Satolas - la place de Lyon dans un réseau européen à grande vitesse - les fonctions des gares Part-Dieu et de Satolas - la garde de Satolas - la place de Lyon dans le réseau TG
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