Flore pittoresque et médicale des Antilles, ou, Histoire naturelle des plantes usuelles des colonies françaises, anglaises, espagnoles et portugaises; par M.E. Descourtilz. Peinte par J. Th. Descourtilz.

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Role of divalent cations, pH, cytoskeleton componentes and surface charge on the adhesion of Trichomonas vaginalis to a polystyrene substrate

The process of adhesion of three different strains of Trichomonas vaginalis to a polystyrene substrate was analysed. The process of adhesion was dependent on the time of incubation and the pH of the phosphate-buffered solution (PBS) in which the parasites were suspended. The highest indices of adhesion were observed after an incubation time of 60 min at pH 6.6. The adhesion index increased when the parasites were incubated in the presence of culture media or when Ca++ or Mg++ was added to the PBS solution, whereas cytochalasin B, trypsin or neuraminidase reduced adhesion. Incubation of the parasites in the presence of poly-L-lysine facilitated the process of adhesion. Incubation of the parasites or polystyrene beads in the presence of poly-L-lysine led to important changes in their surface charge.

Fungi, bacteria and soil pH: the oxalate-carbonate pathway as a model for metabolic interaction

The oxalatecarbonate pathway involves the oxidation of calcium oxalate to low-magnesium calcite and represents a potential long-term terrestrial sink for atmospheric CO2. In this pathway, bacterial oxalate degradation is associated with a strong local alkalinization and subsequent carbonate precipitation. In order to test whether this process occurs in soil, the role of bacteria, fungi and calcium oxalate amendments was studied using microcosms. In a model system with sterile soil amended with laboratory cultures of oxalotrophic bacteria and fungi, the addition of calcium oxalate induced a distinct pH shift and led to the final precipitation of calcite. However, the simultaneous presence of bacteria and fungi was essential to drive this pH shift. Growth of both oxalotrophic bacteria and fungi was confirmed by qPCR on the frc (oxalotrophic bacteria) and 16S rRNA genes, and the quantification of ergosterol (active fungal biomass) respectively. The experiment was replicated in microcosms with non-sterilized soil. In this case, the bacterial and fungal contribution to oxalate degradation was evaluated by treatments with specific biocides (cycloheximide and bronopol). Results showed that the autochthonous microflora oxidized calcium oxalate and induced a significant soil alkalinization. Moreover, data confirmed the results from the model soil showing that bacteria are essentially responsible for the pH shift, but require the presence of fungi for their oxalotrophic activity. The combined results highlight that the interaction between bacteria and fungi is essential to drive metabolic processes in complex environments such as soil.

L'efecte del pH i del sistema de cultiu en el creixement de plantes de raves (Raphanus sativus L. )

Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2008. Es pretén determinar quina influència exerceix el pH i el mètode de cultiu en el creixement i desenvolupament de les plantes de rave. S’han estudiat sis objectius concrets. Primerament, la influència del pH en el creixement de plantes de rave. Segonament, comparar dos sistemes de cultiu hidropònics: amb aigua i amb perlita. Tercerament, determinar la rendibilitat econòmica de cada sistema segons els costos i els resultats obtinguts. En quart lloc, avaluar la possibilitat d’emprar aquests mètodes a major escala i com alternativa al cultiu tradicional al sòl. En cinquè lloc, estudiar per microscòpia electrònica de rastreig els diferents epitelis de la planta. I, finalment, estudiar com afectaria el fenomen de la pluja àcida, mitjançant l’observació de l’efecte de pH àcids en el creixement de la planta.

The murine model of infection with Leishmania major and its importance for the deciphering of mechanisms underlying differences in Th cell differentiation in mice from different genetic backgrounds.

Mice from the majority of inbred strains are resistant to infection by Leishmania major, an obligate intracellular protozoan parasite of macrophages in the mammalian host. In contrast, mice from BALB strains are unable to control infection and develop progressive disease. In this model of infection, genetically determined resistance and susceptibility have been clearly shown to result from the appearance of parasite-specific CD4+ T helper 1 or T helper 2 cells, respectively. This murine model of infection is considered as one of the best experimental systems for the study of the mechanisms operating in vivo at the initiation of polarised T helper 1 and T helper 2 cell maturation. Among the several factors influencing Th cell development, cytokines themselves critically regulate this process. The results accumulated during the last years have clarified some aspects of the role played by cytokines in Th cell differentiation. They are providing critical information that may ultimately lead to the rational devise of means by which to tailor immune responses to the effector functions that are most efficient in preventing and/or controlling infections with pathogens.

Des céramiques aux hommes : étude céramique des premiers horizons fouillés sous la cath��drale Saint-Pierre de Genève (1er millénaire av. J.-C. - 40 apr. J.-C.)

Résumé Le travail présenté est basé sur l'analyse systématique des 145'157 fragments de céramique émanant de 2137 ensembles recueillis entre 1976 et 2003 lors de la fouille de la cath��drale Saint-Pierre. Datés entre le Ier millénaire av. J-C. et le XIXe siècle, ils témoignent de l'ampleur et de la richesse des activités menées au sein de ce site phare de la ville de Genève. Les particularités observées pour les six premiers horizons reconnus, qui couvrent une période comprise entre le Ier millénaire av. J.-C. et 40 apr. J.-C., liées aux structures a priori énigmatiques mises en évidence lors de la fouille, ont orienté le champ d'étude vers une compréhension fine du mobilier recueilli dans ces strates anciennes. Ainsi cadrée, l'étude s'est concentrée sur 237 complexes céramiques ayant livré 23'129 fragments. La corrélation stratigraphique menée sur les 8000 m2 de terrain fouillé a permis de porter l'analyse sur la répartition spatiale du corpus considéré. Développée également sur le plan diachronique, cette démarche a largement contribué à la définition des activités menées sur le site. Ainsi, la concentration de fragments de panses d'amphore et de vaisselle de table importée de Campanie au pied d'un tertre mis en évidence sous le choeur de la cath��drale a conduit à reconnaître l'existence d'un banquet funéraire témoignant de l'ensevelissement sous tumulus d'un aristocrate allobroge décédé entre 120 et 70 av. J.-C. Réparties sur la totalité de la surface occupée par la nef de la cath��drale et des rues la flanquant, les quelques 1024 coupes à boire de La Tène finale mises au jour ont quant à elles permis d'identifier les surfaces de gravier qu'elles scellaient comme une aire de rassemblement ayant abrité des banquets tenus périodiquement. Le maintien de ces activités rituelles et collectives jusqu'au milieu du Ier siècle de notre ère conclut l'analyse diachronique. La mise en perspective historique des données recueillies sur le terrain souligne l'importance de l'antique oppidum extremum des Allobroges, dont le sort fut en 58 av. J.-C. à l'origine de la Guerre des Gaules.

L'apôtre, père et mère de la communauté (1 Th 2,1-12)

La correspondance paulinienne réserve, dans ses passages oubliés, quelques surprises propres à nous faire réviser une image figée de Paul. Ainsi 1 Th 2/1-12, où l'apôtre présente son investissement dans la mission sous la double figure de la mère et du père. Daniel MARGUERAT montre que le vocabulaire affectif afflue dans ce texte où Paul appelle les chrétiens de Thessalonique à identifier dans leur histoire personnelle les traces de la puissance de l'évangile. Conscience collective de l'apostolat et lecture th��ologique des relations interpersonnelles constituent deux accents forts de ce plus ancien écrit de l'apôtre de Tarse.

Hemagglutinating and fusogenic activities of Newcastle disease virus: studies on receptor binding specificity and pH-induced conformational changes

Vaccinal and wild strains of Newcastle Disease virus (NDV) were analyzed for cell receptor binding and fusogenic biological properties associated with their HN (hemagglutinin-neuraminidase) and F (fusion protein) surface structures respectively. The evaluation of the biological activities of HN and F was carried out respectively by determination of hemagglutinating titers and hemolysis percentages, using erythrocytes from various animal origins at different pH values. Significant differences in hemagglutination titers for some strains of NDV were detected, when interacting with goose, sheep, guinea-pip and human "O" group erythrocytes at neutral pH. Diversity of hemolysis percentagens was observed between different NDV strains at acid pH. These analysis were developed to evaluate particular aspects of the actual influence of the receptor specifity and pH on the receptor binding and fusogenic processes of Newcastle Disease viruses.

Glutamate Transport Decreases Mitochondrial pH and Modulates Oxidative Metabolism in Astrocytes.

During synaptic activity, the clearance of neuronally released glutamate leads to an intracellular sodium concentration increase in astrocytes that is associated with significant metabolic cost. The proximity of mitochondria at glutamate uptake sites in astrocytes raises the question of the ability of mitochondria to respond to these energy demands. We used dynamic fluorescence imaging to investigate the impact of glutamatergic transmission on mitochondria in intact astrocytes. Neuronal release of glutamate induced an intracellular acidification in astrocytes, via glutamate transporters, that spread over the mitochondrial matrix. The glutamate-induced mitochondrial matrix acidification exceeded cytosolic acidification and abrogated cytosol-to-mitochondrial matrix pH gradient. By decoupling glutamate uptake from cellular acidification, we found that glutamate induced a pH-mediated decrease in mitochondrial metabolism that surpasses the Ca(2+)-mediated stimulatory effects. These findings suggest a model in which excitatory neurotransmission dynamically regulates astrocyte energy metabolism by limiting the contribution of mitochondria to the metabolic response, thereby increasing the local oxygen availability and preventing excessive mitochondrial reactive oxygen species production.

Isoelectric focusing of alpha-1 acid glycoprotein (orosomucoid) in immobilized pH-gradients with 8M urea: detection of its desialylated variants using an alkaline phosphatase-linked secondary antibody system.

A method allowing a clear separation of the different variants of desialylated alpha 1-acid glycoprotein (orosomucoid) has been developed using isoelectric focusing in immobilized pH gradients, supplemented with 8 M urea and 2% v/v 2-mercaptoethanol. Immunoblotting with two antibody-steps afforded high sensitivity and permitted the detection of about 700 pg of alpha 1-acid glycoprotein in a 20 microL plasma sample diluted 1:28 672. A one year old bloodstrain, kept at room temperature, could easily be phenotyped.

Detection of fingermarks by colloidal gold (MMD/SMD): beyond the pH 3 limit

This work is part of a continuing goal to improve the multimetal deposition technique (MMD), as well as the single-metal deposition (SMD), to make them more robust, more user-friendly, and less labour-intensive. Indeed, two major limitations of the MMD/SMD were identified: (1) the synthesis of colloidal gold, which is quite labour-intensive, and (2) the sharp decrease in efficiency observed when the pH of the working solution is increased above pH 3. About the synthesis protocol, it has been simplified so that there is no more need to monitor the temperature during the synthesis. The efficiency has also been improved by adding aspartic acid, conjointly with sodium citrate, during the synthesis of colloidal gold. This extends the range of pH for which it is possible to detect fingermarks in the frame of the MMD/SMD. The operational range is now extended from 2 to 6.7, compared to 2-3 for the previous formulations. The increased robustness of the working solution may improve the ability of the technique to process substrates that tend to increase the pH of the solution after their immersion.

Incidència del pH de la matèria primera dels nivells de sal afegit i de la temperatura sobre el grau de proteòlisi i la textura del pernil curat

Estudi de l’efecte del pH de la matèria primera, del nivell de sal afegit i de la temperatura sobre el grau de proteòlisi i sobre la textura final del pernil curat per tal de millorar els criteris que s’utilitzen per a la selecció de la matèria primera, avaluar les condiciones de procés òptimes (nivell de sal afegit i de la temperatura de curació) per l’elaboració del pernils destinats al llencat mecànic