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Featured researches published by S. Dufour.


Archive | 2003

Reproductive Endocrinology of the European Eel, Anguilla anguilla

S. Dufour; Elisabeth Burzawa-Gerard; Nadine Le Belle; Miskal Sbaihi; Bernadette Vidal

The mystery of the reproduction of the European eel, in which “seminal liquor nor eggs could never be observed;” was questioned as early as Greek antiquity, by Aristotle, in his writings on “Animal History” and “Animal Generation.” This question initiated a long and still open quest, for the discovery of the eel life cycle and reproduction.


Anatomy and Embryology | 1994

The distribution of GABA-immunoreactive neurons in the brain of the silver eel (Anguilla anguilla L.).

Monique Médina; J. Repérant; S. Dufour; Roger Ward; N. Le Belle; D. Miceli

The distribution of GABA-immunoreactivity was studied in the brain of the silver eel (Anguilla anguilla) by means of antibodies directed against GABA. Immunoreactive neuronal somata were distributed throughout the brain. Positive perikarya were detected in the internal cellular layer of the olfactory bulb, and in all divisions of the telencephalon, the highest density being observed along the midline. Numerous GABA-reactive cell bodies were found in the diencephalon, particularly in the preoptic and tuberal regions of the hypothalamus, and the dorsolateral, dorsomedial and ventromedial thalamic nuclei. In the optic tectum, the majority of GABApositive cell bodies were located in the periventricular layer. A number of immunolabelled cell bodies were observed in different tegmental structures, notably the torus semicircularis. In the cerebellum, the Purkinje cells were either very intensely or very weakly immunoreactive. In the rhombencephalon, reactive cell bodies were observed in the eminentia granularis, the valvula cerebellaris, the octavolateral nucleus, the lobus vagus and in the vagal and glossopharyngeal motor nuclei. Intensely immunoreactive axons and terminals were observed in the external granular layer and internal cellular layer of the olfactory bulb. In the telencephalon, the highest density of reactive fibres and boutons was found in the fields of the medial wall. Many immunolabelled fibres were seen in the medial and lateral forebrain bundles. In the diencephalon, intense labelling of fibres and terminals were observed in the nuclei situated close to the midline. In the optic tectum the highest density of reactive fibres was seen in the sfgs, the layer to which the retina projects massively. Finally, in the rhombencephalon the strongest labelling of neurites was observed in the nuclei of the raphé, the nucleus octavocellularis magnocellularis and the nuclei of the IXth and Xth cranial nerves. The GABAergic system of the eel, which is well developed, appears to be generally comparable to that described in tetrapod vertebrates.


Cell and Tissue Research | 1998

Characterization and localization of two forms of gonadotropin-releasing hormone (GnRH) in the spinal cord of the frog Rana ridibunda

Nicolas Chartrel; Françoise Collin; Yung-Sen Huang; Maïté Montéro; Marie-Christine Tonon; Henk J.Th. Goos; S. Dufour; H. Vaudry

Abstractu2002Two molecular variants of gonadotropin-releasing hormone (GnRH) have been previously characterized in the brain of amphibians, i.e., mammalian GnRH (mGnRH) and chicken GnRH-II (cGnRH-II). The aim of the present study was to identify the molecular forms of gonadotropin-releasing hormone and to localize gonadotropin-releasing hormone-containing elements in the spinal cord of the frog Rana ridibunda using highly specific antisera against mGnRH and cGnRH-II. High-performance liquid chromatography (HPLC) analysis combined with radioimmunoassay (RIA) detection revealed that frog spinal cord extracts contained both mGnRH and cGnRH-II. Immunohistochemical labeling revealed that the frog spinal cord was devoid of GnRH-containing cell bodies. In contrast, numerous GnRH-immunoreactive fibers were observed throughout the entire length of the cord. mGnRH immunoreactivity was only detected in the rostral region of the cord and consisted of varicose processes located in the vicinity of the central canal. cGnRH-II-positive fibers were found throughout the spinal cord, the density of immunoreactive processes decreasing gradually toward the caudal region. Two main cGnRH-II-positive fiber tracts with a rostrocaudal orientation were observed: a relatively dense fiber bundle surrounding the central canal, and a more diffuse plexus in the white matter. In addition, short, varicose cGnRH-II-positive processes with a radial orientation were present throughout the gray matter. These fibers were particularly abundant ventromedially and formed a diffuse network that ramified laterally to end in the vicinity of motoneurons. Taken together, these data indicate that the frog spinal cord, like the frog brain, contains two forms of GnRH. The presence of numerous cGnRH-II-immunoreactive fibers in the ventral horn suggests that cGnRH-II may influence the activity of a subpopulation of motoneurons.


Journal of Endocrinology | 1998

Insulin-like growth factor-I stimulates gonadotrophin production from eel pituitary cells: a possible metabolic signal for induction of puberty

Yung-Sen Huang; Karine Rousseau; N Le Belle; Bernadette Vidal; E. Burzawa-Gérard; J Marchelidon; S. Dufour


International Symposium on the Reproductive Physiology of Fish | 2000

Puberty in teleosts: New insights into the roles of peripheral signals in the stimulation of pituitary gonadotropin

S. Dufour; Yung-Sen Huang; Karine Rousseau; M. Sbaibi; N. LeBelle; Bernadette Vidal; J. Marchelidon; Bruno Quérat; E. Burzawa-Gérard; Ching-Fong Chang; Monika Schmitz


Journal of Endocrinology | 2002

Evidence for a negative feedback in the control of eel growth hormone by thyroid hormones

K Rousseau; N Le Belle; Miskal Sbaihi; J Marchelidon; Monika Schmitz; S. Dufour


Archive | 1996

Gonadotropin-releasing Hormones (GnRH) in Fishes: Evolutionary Data on Their Structure, Localization, Regulation, and Function

Maïté Montero; S. Dufour


Bulletin du Muséum national d'histoire naturelle. Section A, Zoologie, biologie et écologie animales | 1988

Etat sexuel et axe gonadotrope hypothalamo-hypophysaire chez les trois espèces d'anguilles de Tahiti (Anguilla marmorata, A. megastoma et A. obscura)

N. Le Belle; S. Dufour; G. Marquet; B. Kerdelhue; Yves-Alain Fontaine


J. Taiwan Fish.Res | 2001

Multiple neuroendocrine regulation of growth hormone in the European eel, Anquilla anquilla)

S. Dufour; Karine Rousseau; Miskal Sbaihi; N. LeBelle; Bernadette Vidal; J. Marchelidon; Monika Schmitz


Knowledge and Management of Aquatic Ecosystems | 1999

Étude des variations de paramètres anatomiques et endocriniens chez l'anguille européenne (Anguilla anguilla) femelle, sédentaire et d'avalaison : application à la caractérisation du stade argenté

J Marchelidon; N Le Belle; A. Hardy; Bernadette Vidal; Miskal Sbaihi; E. Burzawa-Gérard; Monika Schmitz; S. Dufour

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Bernadette Vidal

Centre national de la recherche scientifique

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J Marchelidon

Centre national de la recherche scientifique

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Karine Rousseau

Centre national de la recherche scientifique

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Yung-Sen Huang

Centre national de la recherche scientifique

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Miskal Sbaihi

National Museum of Natural History

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Bruno Quérat

Centre national de la recherche scientifique

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E. Burzawa-Gérard

Centre national de la recherche scientifique

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J. Marchelidon

Centre national de la recherche scientifique

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Monika Schmitz

Swedish University of Agricultural Sciences

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Ching-Fong Chang

National Taiwan Ocean University

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