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Faivre Évelyne, Bellessort Marie-Noël. Origins 5. Le Caire 13-18 avril 2014. Compte rendu de la conférence internationale organisée au Caire du 13 au 18 avril 2014. In: Archéo-Nil. Revue de la société pour l'étude des cultures prépharaoniques de la vallée du Nil, n°25, 2015. Aux marges de la vallée du Nil. pp. 153-158.

The memory deficits associated with Alzheimer's disease result to a great extent from hippocampal network dysfunction. The coordination of this network relies on theta (symbol) oscillations generated in the medial septum. Here, we investigated in rats the impact of hippocampal amyloid beta (Abeta) injections on the physiological and cognitive functions that depend on the septohippocampal system. Hippocampal Abeta injections progressively impaired behavioral performances, the associated hippocampal theta power, and theta frequency response in a visuospatial recognition test. These alterations were associated with a specific reduction in the firing of the identified rhythmic bursting GABAergic neurons responsible for the propagation of the theta rhythm to the hippocampus, but without loss of medial septal neurons. Such results indicate that hippocampal Abeta treatment leads to a specific functional depression of inhibitory projection neurons of the medial septum, resulting in the functional impairment of the temporal network.

Dlx5 and Dlx6 are two closely associated homeobox genes which code for transcription factors involved in the control of steroidogenesis and reproduction. Inactivation of Dlx5/6 in the mouse results in a Leydig cell defect in the male and in ovarian insufficiency in the female. DLX5/6 are also strongly expressed by the human endometrium but their function in the uterus is unknown. The involvement of DLX5/6 in human uterine pathology is suggested by their strong downregulation in endometriotic lesions and upregulation in endometrioid adenocarcinomas. We first show that Dlx5/6 expression begins in Mullerian ducts epithelia and persists then in the uterine luminal and glandular epithelia throughout post-natal maturation and in the adult. We then use a new mouse model in which Dlx5 and Dlx6 can be simultaneously inactivated in the endometrium using a Pgr(cre/+) allele. Post-natal inactivation of Dlx5/6 in the uterus results in sterility without any obvious ovarian involvement. The uteri of Pgr(cre/+); Dlx5/6(flox/flox) mice present very few uterine glands and numerous abnormally large and branched invaginations of the uterine lumen. In Dlx5/6 mutant uteri, the expression of genes involved in gland formation (Foxa2) and in epithelial remodelling during implantation (Msx1) is significantly reduced. Furthermore, we show that DLX5 is highly expressed in human endometrial glandular epithelium and that its expression is affected in endometriosis. We conclude that Dlx5 and Dlx6 expression determines uterine architecture and adenogenesis and is needed for implantation. Given their importance for female reproduction, DLX5 and DLX6 must be regarded as interesting targets for future clinical research.

Blepharophimosis, ptosis, epicanthus-inversus syndrome (BPES) is an autosomal dominant genetic disorder characterized by narrow palpebral fissures and eyelid levator muscle defects. BPES is often associated to premature ovarian insufficiency (BPES type I). FOXL2, a member of the forkhead transcription factor family, is the only gene known to be mutated in BPES. Foxl2 is essential for maintenance of ovarian identity, but the developmental origin of the facial malformations of BPES remains, so far, unexplained. In this study, we provide the first detailed account of the developmental processes leading to the craniofacial malformations associated to Foxl2. We show that, during development, Foxl2 is expressed both by Cranial Neural Crest Cells (CNCCs) and by Cranial Mesodermal Cells (CMCs), which give rise to skeletal (CNCCs and CMCs) and muscular (CMCs) components of the head. Using mice in which Foxl2 is selectively inactivated in either CNCCs or CMCs, we reveal that expression of Foxl2 in CNCCs is essential for the development of extraocular muscles. Indeed, inactivation of Foxl2 in CMCs has only minor effects on muscle development, whereas its inactivation in CNCCs provokes a severe hypoplasia of the levator palpabrae superioris and of the superior and inferior oblique muscles. We further show that Foxl2 deletion in either CNCCs or CMCs prevents eyelid closure and induces subtle skeletal developmental defects. Our results provide new insights in the complex developmental origin of human BPES and could help to understand the origin of other ocular anomalies associated to this syndrome.

International audience; Foxl2 codes for a forkhead/HNF3 transcription factor essential for follicular maturation and maintenance of ovarian identity. FOXL2 mutations are associated with Blepharophimosis, Ptosis and Epicanthus inversus Syndrome (BPES) characterized by eyelid malformations (types I and II) and premature ovarian insufficiency (type I). We show that Foxl2 is not only expressed by the ovary, but also by other components of the mouse female reproductive tract, including the uterus, the cervix and the oviduct. In the uterus, Foxl2 expression is first observed in the neonatal mesenchyme and, during uterine maturation, persists in the stroma and in the deep inner myometrial layer (IML). In the adult, Foxl2 is expressed in the differentiated stromal layer, but no longer in the myometrium. Conditional deletion of Foxl2 in the postnatal (PN) uterus using Progesterone Receptor-cre (Pgr(cre/+)) mice results in infertility. During PN uterine maturation Pgr(cre/+); Foxl2(flox/flox) mice present a severely reduced thickness of the stroma layer and an hypertrophic, disorganized IML. In adult Pgr(cre/+); Foxl2(flox/flox) mice a supplementary muscular layer is present at the stroma/myometrium border and vascular smooth muscle cells fail to form a coherent layer around uterine arteries. Wnt signalling pathways play a central role in uterine maturation; in Pgr(cre/+); Foxl2(flox/flox) mice, Wnt genes are deregulated suggesting that Foxl2 acts through these signals. In humans, thickening of the IML (also called "junctional zone") is associated with reduced fertility, endometriosis and adenomyosis. Our data suggest that Foxl2 has a crucial role in PN uterine maturation and could help to understand sub-fertility predisposition in women.

International audience; Primary ovarian insufficiency (POI) is characterized by the loss of ovarian function before the age of 40 in humans. Although most cases of POI are idiopathic, many are familial, underlying a genetic origin of the disease. Mutations in genes involved in the control of steroidogenesis, such as NR5A1 (SF-1, Steroidogenic Factor 1), CYP17, CYP19A1 (aromatase), StAR (Steroidogenic Acute Regulatory), and the forkhead transcription factor FOXL2 have been associated with different forms of POI. In males, the homeobox transcription factors Dlx5 and Dlx6 are involved in the control of steroidogenesis through the activation of GATA4-induced-StAR transcription. Here, we analyze the potential involvement of Dlx5 and Dlx6 in female reproduction. To this end, we make use of an existing mouse model in which Dlx5 and Dlx6 are simultaneously disrupted. We show that: (i) allelic reduction of Dlx5 and Dlx6 in the mouse results in a POI-like phenotype, characterized by reduced fertility and early follicular exhaustion; (ii) in granulosa cell lines, a reciprocal regulation exists between Dlx5 and Foxl2; (iii) in the mouse ovary, allelic reduction of Dlx5/6 results in the upregulation of Foxl2. We propose that the mutual regulation between Dlx5/6 and Foxl2 and their opposite effects on StAR expression might contribute to determine the homeostatic control of steroidogenesis within the ovary. Dysregulation of this homeostatic control would result in abnormal follicular maturation and reduced fertility. Our results bring new elements to our conceptual model of follicle maturation and maintenance and provide new potential genetic targets for cases of familial POI.

L’évolution du littoral camarguais, liée principalement aux modifications du delta du Rhône, est caractérisée par la prédominance des érosions. Pour lutter contre celles-ci, il a été réalisé jusque lors des aménagements répondant, pour l’essentiel, aux conditions et besoins locaux. Le Parc Régional Naturel de Camargue a souhaité qu’il soit réalisé une étude permettant de définir des stratégies d’aménagement globales du littoral camarguais. Elle a été confiée au Groupement SOGREAH-AQUASCOP et a abordé les points suivants : . régime et évolution du littoral ; . enjeux économiques et vocations des zones ; . classification du littoral selon sa vulnérabilité ; . stratégie d’aménagement en prenant en compte des surélévations au niveau marin de 0,40 m et de 0,60 m ; . suivi des aménagements. Les principaux points de l’étude sont : . le moteur essentiel de l’évolution du littoral est l’agitation, . l’évolution du littoral est très liée à l’histoire du delta dans un passé récent et, notamment, au dernier déplacement du delta du Grand Rhône en 1711, . il n’y a pas de raisons que les tendances évolutives actuelles se modifient dans un avenir proche, . trois stratégies d’aménagement ont été proposées : intervention minimale, maintien de la situation actuelle, amélioration de la situation actuelle ; il a été recommandé de favoriser les solutions " rechargements " (notamment avec des galets) qui apportent le moins de perturbations à l’environnement., Viguier Jacques, Bellessort Bernard, Mazoyer C. Le littoral camarguais : évolution et stratégie d'aménagement. In: L'eau, l'homme et la nature. 24èmes journées de l'hydraulique. Congrès de la Société Hydrotechnique de France. Paris, 18-19-20 septembre 1996. 1996.

To define coastal amenities, the engineer has first to work out a diagnosis for hydraulic and sedimentologic processes (What ? How ?, How much ? Budget), and then examine various solutions. To reach these objectives, he uses methods of study extending from natural data to physical and/or numerical models. Contributions on the limits of these various methods are examined., Pour définir un aménagement du littoral, l'ingénieur doit, en premier lieu, établir un diagnostic quant au régime hydraulique et sédimentologique (Quoi ? Comment ? Combien ? Bilan) puis examiner les diverses solutions. Pour atteindre les objectifs, il met en oeuvre des moyens d'études allant de l'analyse des données naturelles à la mise en oeuvre des moyens "lourds" tels que les modèles physiques et/ou numériques. Les apports et limites de ces diverses méthodes sont examinés., Bellessort Bernard. L’ingénieur et les études d’aménagement du littoral. Les moyens d’étude, de la nature aux modèles physiques et numériques. In: Cahiers du Centre nantais de recherche pour l'aménagement régional, n°41-42, 1994. Défense des côtes ou protection de l'espace littoral, quelles perspectives ? Actes du colloque international (17-20 octobre 1991) pp. 205-213.

Ce document propose, dans le cadre de l'étude d'impact des aménagements de l'estuaire de la Loire à Donges-Est, des mesures compensatoires pour conserver à l'estuaire sa richesse biologique.

Within the framework of the Loire estuary development, the Nantes-Saint-Nazaire Port Authority initiated a set of studies to define compatibility between the possible estuary developments and conservation of living natural environment. The main points of this program were as follows:−studies of hydraulic and sedimentary phenomena (desk, field and model studies)−studies of water quality−benthos, ichtyological and wet zones studies.

Sous l'action de la houle les sédiments peuvent être soumis à différents mouvements se traduisant par de simples oscillations sur place, des déplacements dans le profil perpendiculairement à la côte ou un transit littoral dont la direction et l'importance dépendront essentiellement des caractéristiques de la houle, des matériaux et du profil des fonds. La nombreuse documentation disponible sur ce sujet pourrait faire penser que ces problèmes sont bien connus et qu'il suffit d'appliquer un certain nombre de formules existant dans la littérature pour avoir une réponse précise sur le comportement des galets, graviers, sables ou vases répartis à différentes profondeurs du pré-continent.

French shore general view about impacts of various kinds of improvments. Rules of improvment About 1 000 structures perpendicular to shore (50 km cumulated), 500 along shore (400 km cumulated) and 300 harbor or river mouth structures. These figures illustrate the magnitude of works on the french coastline and that of their associated impacts. After examining the shore natural evolution parameters, examples of impacts due to the type of structure with respect to the local littoral regime are considered. Then protection principles are proposed., Environ 1 000 ouvrages transversaux (50 km développés), 500 longitudinaux (400 km développés) et 300 ouvrages portuaires ou de débouchés en mer. Ce bilan illustre l'importance des aménagements sur le littoral français et aussi ceux des impacts qui leur sont associés. Après avoir examiné les facteurs d'évolution naturels du littoral, il a été abordé, à l'aide d'exemples, les impacts qui découlent d'une part du régime littoral existant et d'autre part du type d'aménagement envisagé. Des principes d'aménagement ont ensuite été définis., Bellessort Bernard. Rapport V.2 Le littoral français. Vue d'ensemble sur les impacts des divers types d'aménagements. Principes d'aménagement. In: L'hydraulique et la maitrise du littoral. Problèmes côtiers posés par le mouvement des sédiments et la pollution. Dix-huitièmes journées de l'hydraulique. Marseille, 11-13 septembre 1984. Tome 5, 1984.

Bellessort André. Un romantique Suédois : Almqwist. In: La revue pédagogique, tome 56, Janvier-Juin 1910. pp. 41-64.

Bellessort André. Boileau, bourgeois de Paris. In: La revue pédagogique, tome 58, Janvier-Juin 1911. pp. 233-253.