Rouvier Henri, Henry Bernard, Le Goff Maxime, Macquar Jean-Claude, Thibieroz Jacques, Lewchuk Michael T., Leach David. Dating of a widespread remagnetization on the Southeastern border of the French ...Massif Central and implications for a regional fluids migration relative to Pyrenean orogeny. In: Transferts dans les systèmes sédimentaires : de l'échelle du pore à celle du bassin. Réunion spécialisée SGF-TRABAS/CNRS, Paris 27-28 septembre 1999. Résumés. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1999. pp. 121-122. (Sciences Géologiques. Mémoire, 99)
The Trw Type IV Secretion System of Bartonella Mediates Host-Specific Adhesion to Erythrocytes Vayssier-Taussat , Muriel (INRA , Versailles (France). UMR 1318 Institut Jean-Pierre BOURGIN); Le Rhun , Danielle (INRA , Maisons-Alfort (France). UMR 0956 Biologie Moléculaire et Immunologie Parasitaires et Fongiques); Deng , H.K. (INRA , Maisons-Alfort (France). UMR 0956 Biologie Moléculaire et Immunologie Parasitaires et Fongiques) ...
2010
Publication
Bacterial pathogens typically infect only a limited range of hosts; however, the genetic mechanisms governing host-specificity are poorly understood. The alpha-proteobacterial genus Bartonella ...comprises 21 species that cause host-specific intraerythrocytic bacteremia as hallmark of infection in their respective mammalian reservoirs, including the human-specific pathogens Bartonella quintana and Bartonella bacilliformis that cause trench fever and Oroya fever, respectively. Here, we have identified bacterial factors that mediate host-specific erythrocyte colonization in the mammalian reservoirs. Using mouse-specific Bartonella birtlesii, human-specific Bartonella quintana, cat-specific Bartonella henselae and rat-specific Bartonella tribocorum, we established in vitro adhesion and invasion assays with isolated erythrocytes that fully reproduce the host-specificity of erythrocyte infection as observed in vivo. By signature-tagged mutagenesis of B. birtlesii and mutant selection in a mouse infection model we identified mutants impaired in establishing intraerythrocytic bacteremia. Among 45 abacteremic mutants, five failed to adhere to and invade mouse erythrocytes in vitro. The corresponding genes encode components of the type IV secretion system (T4SS) Trw, demonstrating that this virulence factor laterally acquired by the Bartonella lineage is directly involved in adherence to erythrocytes. Strikingly, ectopic expression of Trw of rat-specific B. tribocorum in cat-specific B. henselae or human-specific B. quintana expanded their host range for erythrocyte infection to rat, demonstrating that Trw mediates host-specific erythrocyte infection. A molecular evolutionary analysis of the trw locus further indicated that the variable, surface-located TrwL and TrwJ might represent the T4SS components that determine host-specificity of erythrocyte parasitism. In conclusion, we show that the laterally acquired Trw T4SS diversified in the Bartonella lineage to facilitate host-restricted adhesion to erythrocytes in a wide range of mammals.
In northwestern Tunisia, a paleomagnetic study was carried out on Albian levels, objects of controversy. They are considered to be either overturned strata on the limb of diapirs, or in their upright ...position as the floor of a salt glacier. After correction for the apparent dip, the polarity of the primary magnetization is always reversed, and the magnetization directions are relatively scattered. The Earth's magnetic field was always of normal polarity during the Albian, so that these levels are overturned. The scattering of the magnetization direction points out moreover that the tilting occurred around axes of various orientations. All these observations show that the evaporitic bodies were emplaced in diapirs, and that the notion of a salt glacier interbedded within the Albian sediments has to be given up.
Une étude paléomagnétique a été réalisée sur des terrains albiens en Tunisie nord-occidentale. Ces terrains sont considérés comme étant, pour certains auteurs, en série inverse sur le flanc d'appareils diapiriques, pour d'autres en série normale comme plancher d'un glacier de sel. Après correction du pendage apparent, la polarité de l'aimantation primaire est toujours inverse, avec des déclinaisons différentes d'un site à l'autre. Le champ magnétique à cette période ayant toujours été de polarité normale, il faut admettre que ces terrains sont renversés. La dispersion des déclinaisons montre de plus que les renversements ont eu lieu autour d'axes d'orientations variés. Tout ceci indique que les corps évaporitiques se sont mis en place grâce à des structures diapiriques, et implique que le concept de glacier de sel interstratifié dans l'Albien doit être abandonné.
Breuil Henri, Vaultier Maxime, Zbyszewski Georges. Les Plages anciennes portugaises entre les Caps d'Espichel et Carvoeiro et leurs industries paléolithiques. In: Bulletin de la Société préhistorique ...de France, tome 39, n°3-4, 1942. pp. 93-98.
Breuil Henri, Vaultier Maxime, Zbyszewski Georges. Les plages anciennes portugaises entre le cap d'Espichel et la presqu'île de Peniche et leurs industries paléolithiques. In: Comptes rendus des ...séances de l'Académie des Inscriptions et Belles-Lettres, 86ᵉ année, N. 2-3, 1942. pp. 102-109.
