Species-wide distribution of highly polymorphic minisatellite markers suggests past and present genetic exchanges among house mouse subspecies

Global analysis of four minisatellite loci in House Mouse reveals unexpected long-range gene flow between populations and subspecies

Mecanismos efectores del interferón gamma contra la infección por Toxoplasma gondii

Toxoplasma gondii is an intracellular obligate protozoan parasite, Human infection is generally subclinical, but hosts with deffective cellular immunity are at risk of severe disease. In many countries, congenital toxoplasmosis and toxoplasmic encephalitis in HIV-infected individuals are significant causes of morbidity and mortality. We review here the effector mechanisms of gamma interferon, the major cytokine involved in the protection against T gondii The addition of IFN y to cultured infected THPl cells protected against Tgondii infection by an early mechanism involving a reduction in the number of parasitized cells.The reduction in the percentage of parasitized cells obtained by treatment with IFN y is linked to a decrease in parasite and cellular PLA, activity.This is a new effector mechanism of IFN y against T gondii infection. A second effect is by inducing indoleamine-oxigenase (IDO), an enzyme that reduces tryptophan stores.Tryptophan is essential for intracellular growth of T gondii. lnduction of IDO leads to a parasitostatic effect. In human monocytes induction of nitric oxide is not a part of the antitoxoplasmicidal effect induced by IFN y.Toxoplasma gondiies un protozoario parásito de desarrollo intracelular. La enfermedad humana producida por T: gondii es una causa importante de morbilidad y mortalidad neonatal y en pacientes inmunodeprimidos. En esta reseña, se revisan los conocimientos actuales sobre los mecanismos efectores del interferón gamma (IFN y), la principal citocina protectora contra Igondii, incluyendo los resultados que hemos obtenido en un modelo de infección in vifro de células humanas monocitarias (THPI). El IFN y protege las células humanas contra T gondii por mecanismos diferentes a aquéllos con los que protege las células de ratón. En el modelo de infección de célulasTHP1, el IFN y protege por dos mecanismos independientes. Un primer efecto es la reducción del porcentaje de células parasitadas, el cual está ligado a una disminución de la actividad PLA, parasitaria y celular. Se trata de un nuevo mecanismo efector del IFN y contra la infección toxoplásmica, diferente a los mecanismos parasiticidas y parasitostáticos previamente descritos. Un segundo efecto ocurre por interrupción del crecimiento parasitario intracelular a través de la activación de la enzima indoleamina-oxigenasa que degrada el triptófano, lo que constituye un efecto parasitostático. Contrariamente a lo que ocurre en el modelo de infección de células monocitarias de ratón, la producción de óxido nítrico (NO) no juega un papel determinante en los monocitos humanos

Elastic instability in stratified core annular flow

We study experimentally the interfacial instability between a layer of dilute polymer solution and water flowing in a thin capillary. The use of microfluidic devices allows us to observe and quantify in great detail the features of the flow. At low velocities, the flow takes the form of a straight jet, while at high velocities, steady or advected wavy jets are produced. We demonstrate that the transition between these flow regimes is purely elastic -- it is caused by viscoelasticity of the polymer solution only. The linear stability analysis of the flow in the short-wave approximation captures quantitatively the flow diagram. Surprisingly, unstable flows are observed for strong velocities, whereas convected flows are observed for low velocities. We demonstrate that this instability can be used to measure rheological properties of dilute polymer solutions that are difficult to assess otherwise.Comment: 4 pages, 4 figure

Dégradation des galactolipides par les protozoaires et les bactéries du contenu du caecum de cheval

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Attachement des Ciliés du caecum de Cheval aux fragments végétaux. — Dégradation des chloroplastes. — Attachement des bactéries aux Ciliés du caecum

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Phylogeography and postglacial expansion of Mus musculus domesticus inferred from mitochondrial DNA coalescent, from Iran to Europe

International audienceFew genetic data document the postglacial history of the western house mouse, Mus musculus domesticus. We address this by studying a sample from the southeastern tip of the Fertile Crescent in the Iranian province of Ahvaz. Including other published and unpublished data from France, Germany, Italy, Bulgaria, Turkey and other places in Iran, altogether 321 mitochondrial D-loop sequences are simultaneously analysed. The patterns of coalescence obtained corroborate the classical proposal according to which the Fertile Crescent is where commensalism with humans has started in the Western Hemisphere, and from where the subspecies has expanded further west. Our data also clearly show that despite multiple colonisations and long-range transportation, there is still a rather high Phi(ST) of 0.39. The original expansion signal is still recognisable, with two well-separated derived clades, allowing us to propose a hypothetical scenario in which expansion toward Europe and Asia Minor took at least two routes, tentatively termed the Mediterranean and the Bosphorus/Black Sea routes. This scenario resembles that of another domesticated species, the goat, and fits with the known progression of Neolithic culture. Given the concomitance of both phenomena around 12 000 years ago, we propose a recalibration of the D-loop mutation rate to a much faster tick of similar to 40% per site per million years (Myr). This value should be used for intrasubspecific polymorphism, while the interspecific rate in Mus is presently estimated at 6-10%/site/Myr. This is in keeping with the now well recognised fact that only a subfraction of segregating mutations go to fixation

Te-rich Ge-As-Se-Te bulk glasses and films for future infrared integrated optics

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Etude in vitro du comportement des populations microbiennes du rumen en présence de zinc sous forme de sulfate

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Influence du cobalt et de la vitamine B12 sur la croissance et la survie des ciliés du rumen in vitro, en fonction de la population bactérienne

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