Observation de la mobilité et des dynamiques urbaines : indicateurs d'accessibilité automobile aux équipements structurants des aires urbaines : application à 10 aires urbaines

L'objectif de cette étude est de proposer des indicateurs d'accessibilité automobile aux équipements structurants des aires urbaines, non pas en fonction des distances parcourues, mais en fonction des «espaces temps» dans lesquels évoluent les gens. Ces « espaces temps » sont envisagés ici sous forme de courbes isochrones à partir des principaux grands types d'équipements. L'approche proposée s'appuie sur une modélisation du réseau routier de la BDCarto de l'IGN afin de déterminer une heure de pointe. Cette heure de pointe varie selon les aires urbaines. La première partie du document définit le cadre général de l'étude, son contexte et ses objectifs. La seconde partie décrit la méthode mise en place et les indicateurs développés. La troisième partie présente une synthèse des résultats obtenus. Enfin, les compléments de méthode et l'ensemble des résultats sont reportés en annexe du document

Contributions of Andrée Tixier-Vidal (1923-2021) to modern cell biology

International audienceThis article illustrates the main stages of the scientific career of Dr Andrée Tixier-Vidal, a pioneer in cell biology research in France. She made important discoveries in the field of hormone secretion and neuronal morphogenesis. She played a key role in developing pituitary and neuronal cultures and using electron microscopy to study cellular structures. Her scientific influence continues to irradiate through her students and collaborators

Emissions polluantes et trafic routier

Planchon Florent, Delahaye Daniel, Tougard Claude. Emissions polluantes et trafic routier. In: Études Normandes, 48e année, n°1-2, 1999. Le puzzle rouennais - Géoscopie du Grand Rouen. pp. 171-178

Proteolytic Processing of Sulfated Secretogranin II in the trans -Golgi Network of GH3B6 Prolactin Cells

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Observation de la mobilité et des dynamiques urbaines : indicateurs d'accessibilité automobile aux équipements structurants des aires urbaines : application à 10 aires urbaines

L'objectif de cette étude est de proposer des indicateurs d'accessibilité automobile aux équipements structurants des aires urbaines, non pas en fonction des distances parcourues, mais en fonction des «espaces temps» dans lesquels évoluent les gens. Ces « espaces temps » sont envisagés ici sous forme de courbes isochrones à partir des principaux grands types d'équipements. L'approche proposée s'appuie sur une modélisation du réseau routier de la BDCarto de l'IGN afin de déterminer une heure de pointe. Cette heure de pointe varie selon les aires urbaines. La première partie du document définit le cadre général de l'étude, son contexte et ses objectifs. La seconde partie décrit la méthode mise en place et les indicateurs développés. La troisième partie présente une synthèse des résultats obtenus. Enfin, les compléments de méthode et l'ensemble des résultats sont reportés en annexe du document

Immunocytochemical Localization of the Prohormone Convertases PC1 and PC2 in Rat Prolactin Cells

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Identification of Multiple Subunits of Heterotrimeric G Proteins on the Membrane of Secretory Granules in Rat Prolactin Anterior Pituitary Cells

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Heterodimerization of Endothelin-converting Enzyme-1 Isoforms Regulates the Subcellular Distribution of This Metalloprotease

International audienceEndothelin-converting enzyme (ECE) is a membrane metalloprotease that generates endothelin from its direct precursor big endothelin. Four isoforms of ECE-1 are produced from a single gene through the use of alternate promoters. These isoforms share the same extracellular catalytic domain and contain unique cytosolic tails, which results in their specific subcellular targeting. We investigated the distribution of ECE-1 isoforms in transfected AtT-20 neuroendocrine cells. Whereas ECE-1a and 1c were present at the plasma membrane, ECE-1b and ECE-1d were retained inside the cells. We found that both intracellular isoforms were concentrated in the endosomal system: ECE-1d in recycling endosomes, and ECE-1b in late endosomes/multivesicular bodies. Leucine-based motifs were involved in the intracellular retention of these isoforms, and the targeting of ECE-1b to the degradation pathway required an additional signal in the N terminus. The concentration of ECE-1 isoforms in the endosomal system suggested new functions for these enzymes. Potential novel functions include redistribution of other isoforms through direct interaction. We have showed that ECE-1 isoforms could heterodimerize, and that in such heterodimers the ECE-1b targeting signal was dominant. Interaction of a plasma membrane isoform with ECE-1b resulted in its intracellular localization and decreased its extracellular activity. These data demonstrated that the targeting signals specific for ECE-1b constitute a regulatory domain per se that could modulate the localization and the activity of other isoforms

Differential implication of deoxyribonucleic acid methylation in rat prolactin and rat growth hormone gene expressions: a comparison between rat pituitary cell strains

In order to assess the potential role of DNA methylation in the expression of rat PRL (rPRL) as compared to rat GH (rGH) gene, the cleavage patterns generated by the isoschizomeric restriction enzymes HpaII and MspI were examined in DNA isolated from rat pituitary cell lines producing either high levels of rPRL (GH3B6) or of rGH (GC) and in a stable variant cell strain which produces minute amounts of both hormones (GH3CDL cells). The rPRL and the rGH genes were found hypomethylated in GH3B6 and GC cells, respectively, whereas in GH3CDL cells both genes were methylated, indicating a correlation between the extent of gene methylation and the level of expression. However the use of 5-azacytidine (5-azaC), which decreases DNA methylation, suggested a variable importance of gene methylation in the control of rPRL and rGH gene expression. 5-AzaC was unable to increase rPRL production to a detectable level in GC cells, whereas the cytidine analog markedly increased rPRL production and rGH production in GH3CDL cells. Further analysis using GH3CDL cells showed that the extent of the 5-azaC-induced rPRL and rGH gene demethylation was consistent with the 5-azaC-induced increase of gene expressions. However, in these cells, the stimulation of rPRL and rGH production unexpectedly increased as a function of time elapsed after drug withdrawal. The maximal stimulation, 30-fold and 7-fold, respectively, was observed 3 weeks after a 60-h exposure to 5-azaC. This pattern suggests that other events are required for the full expression of rPRL and rGH genes in addition to their own demethylation