Les mécanismes d'action du Bisphénol A

L’exposition au bisphénol A (BPA) se fait essentiellement par la consommation de nourriture contaminée au contact de polycarbonates et de résines. Elle concerne, dans les pays industrialisés, la majeure partie de la population ; cette substance a été détectée dans 95% des échantillons d’urine analysés et retrouvée dans le liquide amniotique, le plasma fœtal et maternel, le placenta et le lait maternel. Cette ubiquité suggère que le BPA peut affecter la santé humaine

Perinatal exposure to methoxychlor enhances adult cognitive responses and hippocampal neurogenesis in mice

International audienceDuring perinatal life, sex steroids, such as estradiol, have marked effects on the development and function of the nervous system. Environmental estrogens or xenoestrogens are man-made chemicals, which animal and human population encounter in the environment and which are able to disrupt the functioning of the endocrine system. Scientific interest in the effects of exposure to xenoestrogens has focused more on fertility and reproductive behaviors, while the effects on cognitive behaviors have received less attention. Therefore, the present study explored whether the organochlorine insecticide Methoxychlor (MXC), with known xenoestrogens properties, administered during the perinatal period (from gestational day 11 to postnatal day 8) to pregnant-lactating females, at an environmentally relevant dose (20 µg/kg (body weight)/day), would also affect learning and memory functions depending on the hippocampus of male and female offspring mice in adulthood. When tested in adulthood, MXC perinatal exposure led to an increase in anxiety-like behavior and in short-term spatial working memory in both sexes. Emotional learning was also assessed using a contextual fear paradigm and MXC treated male and female mice showed an enhanced freezing behavior compared to controls. These results were correlated with an increased survival of adult generated cells in the adult hippocampus. In conclusion, our results show that perinatal exposure to an environmentally relevant dose of MXC has an organizational effect on hippocampus-dependent memory and emotional behaviors

Forces et Faiblesses en Matière de Redevabilité dans le Secteur de l’Eau dans les Communes d’Ifangni et de Sakété (Bénin)

La redevabilité exige que les tous les acteurs impliqués dans un service public assument la responsabilité de leurs actes et omissions, reconnaissent qu’ils ont des comptes à rendre sur leurs actes ou manquements et qu’ils doivent adapter leurs politiques et actions en conséquence. Ce travail de recherche a évalué les forces et faiblesses de la mise en œuvre de la redevabilité dans le secteur de l’eau potable dans les communes d’Ifangni et de Sakété au sud du Bénin. La démarche méthodologique est basée sur la collecte des données, le traitement manuel et statistique de ces données et l'analyse des résultats, grâce au modèle d'analyse SWOT. Les données sont collectées à partir des recherches bibliographiques et des enquêtes de terrain réalisées dans 208 ménages à Ifangni et dans 150 ménages à Sakété, auprès du Responsable Eau et Assainissement (REA) et de personnes ressources. Les résultats ont montré que les textes de loi existent aussi bien au niveau local que national pour obliger les acteurs en charge du secteur de l’eau à être redevables de leurs engagements formels en vue de fournir de l’eau à la population. Cette population aussi sait qu’elle a des droits de réclamer des comptes à ces acteurs mais l’existence de contingences socio-politiques et le faible niveau d’appropriation du concept et des outils de redevabilité expliquent la faiblesse qui caractérise la mise en œuvre de ce mécanisme et son impact négatif sur le service de fourniture d’eau

Metabolic characterization of green pods from Vanilla planifolia accessions grown in La Reunion.

Large phenotypic variation has been observed between the cultivated vanillas since a single genetic source of Vanilla planifolia was spread to the Indian Ocean and the Indonesia in the 19th century. In order to differentiate the cultivated vanilla plants, genetic studies have been conducted in the past on the plants grown in various regions such as the French island, La Réunion. However, the genetic difference was not big enough to differentiate diverse accessions of V. planifolia. In this study, metabolomics, in which genetic variation could be amplified, was employed to delve into the variation between the cultivated vanilla plants. To obtain a broad view of the metabolome, nuclear magnetic resonance (NMR) spectroscopy was applied to the analysis of V. planifolia green pods. Principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) of the data showed that the accessions could be differentiated according to their glucovanillin and glucosides A and B contents. Furthermore, a correlation between the glucovanillin content and the pod length, number of flower and growth capacity of the accessions has been observed from the multivariate data analysis

Shoot differentiation from protocorm callus cultures of Vanilla planifolia (Orchidaceae): proteomic and metabolic responses at early stage

<p>Abstract</p> <p>Background</p> <p><it>Vanilla planifolia </it>is an important Orchid commercially cultivated for the production of natural vanilla flavour. Vanilla plants are conventionally propagated by stem cuttings and thus causing injury to the mother plants. Regeneration and <it>in vitro </it>mass multiplication are proposed as an alternative to minimize damage to mother plants. Because mass production of <it>V. planifolia </it>through indirect shoot differentiation from callus culture is rare and may be a successful use of in <it>vitro </it>techniques for producing somaclonal variants, we have established a novel protocol for the regeneration of vanilla plants and investigated the initial biochemical and molecular mechanisms that trigger shoot organogenesis from embryogenic/organogenic callus.</p> <p>Results</p> <p>For embryogenic callus induction, seeds obtained from 7-month-old green pods of <it>V. planifolia </it>were inoculated on MS basal medium (BM) containing TDZ (0.5 mg l^-1). Germination of unorganized mass callus such as protocorm -like structure (PLS) arising from each seed has been observed. The primary embryogenic calli have been formed after transferring on BM containing IAA (0.5 mg l^-1) and TDZ (0.5 mg l^-1). These calli were maintained by subculturing on BM containing IAA (0.5 mg l^-1) and TDZ (0.3 mg l^-1) during 6 months and formed embryogenic/organogenic calli. Histological analysis showed that shoot organogenesis was induced between 15 and 20 days after embryogenic/organogenic calli were transferred onto MS basal medium with NAA (0.5 mg l^-1). By associating proteomics and metabolomics analyses, the biochemical and molecular markers responsible for shoot induction have been studied in 15-day-old calli at the stage where no differentiating part was visible on organogenic calli. Two-dimensional electrophoresis followed by matrix-assisted laser desorption ionization time-of-flight-tandem mass spectrometry (MALDI-TOF-TOF-MS) analysis revealed that 15 protein spots are significantly expressed (<it>P </it>< 0.05) at earlier stages of shoot differentiation. The majority of these proteins are involved in amino acid-protein metabolism and photosynthetic activity. In accordance with proteomic analysis, metabolic profiling using 1D and 2D NMR techniques showed the importance of numerous compounds related with sugar mobilization and nitrogen metabolism. NMR analysis techniques also allowed the identification of some secondary metabolites such as phenolic compounds whose accumulation was enhanced during shoot differentiation.</p> <p>Conclusion</p> <p>The subculture of embryogenic/organogenic calli onto shoot differentiation medium triggers the stimulation of cell metabolism principally at three levels namely (i) initiation of photosynthesis, glycolysis and phenolic compounds synthesis; (ii) amino acid - protein synthesis, and protein stabilization; (iii) sugar degradation. These biochemical mechanisms associated with the initiation of shoot formation during protocorm - like body (PLB) organogenesis could be coordinated by the removal of TDZ in callus maintenance medium. These results might contribute to elucidate the complex mechanism that leads to vanilla callus differentiation and subsequent shoot formation into PLB organogenesis. Moreover, our results highlight an early intermediate metabolic event in vanillin biosynthetic pathway with respect to secondary metabolism. Indeed, for the first time in vanilla tissue culture, phenolic compounds such as glucoside A and glucoside B were identified. The degradation of these compounds in specialized tissue (i.e. young green beans) probably contributes to the biosynthesis of glucovanillin, the parent compound of vanillin.</p

Differences in the signaling pathways of α1A- and α1B-adrenoceptors are related to different endosomal targeting

Aims: To compare the constitutive and agonist-dependent endosomal trafficking of α1A- and α1B-adrenoceptors (ARs) and to establish if the internalization pattern determines the signaling pathways of each subtype. Methods: Using CypHer5 technology and VSV-G epitope tagged α1A- and α1B-ARs stably and transiently expressed in HEK 293 cells, we analyzed by confocal microscopy the constitutive and agonist-induced internalization of each subtype, and the temporal relationship between agonist induced internalization and the increase in intracellular calcium (determined by FLUO-3 flouorescence), or the phosphorylation of ERK1/2 and p38 MAP kinases (determined by Western blot). Results and Conclusions: Constitutive as well as agonist-induced trafficking of α1A and α1B ARs maintain two different endosomal pools of receptors: one located close to the plasma membrane and the other deeper into the cytosol. Each subtype exhibited specific characteristics of internalization and distribution between these pools that determines their signaling pathways: α1A-ARs, when located in the plasma membrane, signal through calcium and ERK1/2 pathways but, when translocated to deeper endosomes, through a mechanism sensitive to β-arrestin and concanavalin A, continue signaling through ERK1/2 and also activate the p38 pathway. α1B-ARs signal through calcium and ERK1/2 only when located in the membrane and the signals disappear after endocytosis and by disruption of the membrane lipid rafts by methyl-β-cyclodextrin

Exploring the Phytobeneficial and Biocontrol Capacities of Endophytic Bacteria Isolated from Hybrid Vanilla Pods.

peer reviewedIn this study, 58 endophytic bacterial strains were isolated from pods of two hybrid vanilla plants from Madagascar, Manitra ampotony and Tsy taitra. They were genetically characterized and divided into four distinct phylotypes. Three were associated to genus Bacillus species, and the fourth to the genus Curtobacterium. A selection of twelve strains corresponding to the identified genetic diversity were tested in vitro for four phytobeneficial capacities: phosphate solubilisation, free nitrogen fixation, and phytohormone and siderophore production. They were also evaluated in vitro for their ability to biocontrol the growth of the vanilla pathogenic fungi, Fusarium oxysporum f. sp. radicis vanillae and Cholletotrichum orchidophilum. Three bacteria of phylotype 4, m62a, m64 and m65, showed a high nitrogen fixation capacity in vitro, similar to the Pseudomonas florescens F113 bacterium used as a control (phospate solubilizing efficiency respectively 0.50 ± 0.07, 0.43 ± 0.07 and 0.40 ± 0.06 against 0.48 ± 0.03). Strain t2 related to B. subtilis showed a higher siderophore production than F113 (respectively 1.40 ± 0.1 AU and 1.2 ± 0.1 AU). The strain m72, associated with phylotype 2, showed the highest rate of production of Indole-3-acetic acid (IAA) in vitro. Bacteria belonging to the pylotype 4 showed the best capacity to inhibit fungal growth, especially the strains m62b m64 and t24, which also induced a significant zone of inhibition, suggesting that they may be good candidates for controlling fungal diseases of vanilla. This competence was highlighted with spectral imaging showing the production of lipopeptides (Iturin A2 and A3, C16 and C15-Fengycin A and C14 and C15-Surfactin) by the bacterial strains m65 confronted with the pathogenic fungi of vanilla.FEDER BIOMED HUB Technology Suppor