What science for what democracy?

The transformations undergone by research and science in the name of the so called "knowledge economy" cover the decisions of scientific policies and the "management" of research, and also the meaning of scientific activities (devoted to innovation) and even more fundamentally the very structure of the sciences (transformed to technosciences). The science that is contributing to capitalist competitiveness (and to the current economic crisis) is not the same as that which would be able to contribute "to the conception and democratic carrying out of another form of globalization and another European project". However, this is not self-evident, and it needs to be thought about since it is not simply a matter of returning to the science of the 20th century that opened the way to technoscience

Boolean Models of Biosurfactants Production in Pseudomonas fluorescens

Cyclolipopeptides (CLPs) are biosurfactants produced by numerous Pseudomonas fluorescens strains. CLP production is known to be regulated at least by the GacA/GacS two-component pathway, but the full regulatory network is yet largely unknown. In the clinical strain MFN1032, CLP production is abolished by a mutation in the phospholipase C gene () and not restored by complementation. Their production is also subject to phenotypic variation. We used a modelling approach with Boolean networks, which takes into account all these observations concerning CLP production without any assumption on the topology of the considered network. Intensive computation yielded numerous models that satisfy these properties. All models minimizing the number of components point to a bistability in CLP production, which requires the presence of a yet unknown key self-inducible regulator. Furthermore, all suggest that a set of yet unexplained phenotypic variants might also be due to this epigenetic switch. The simplest of these Boolean networks was used to propose a biological regulatory network for CLP production. This modelling approach has allowed a possible regulation to be unravelled and an unusual behaviour of CLP production in P. fluorescens to be explained

Epigenetic acquisition of inducibility of type III cytotoxicity in P. aeruginosa

BACKGROUND: Pseudomonas aeruginosa, an opportunistic pathogen, is often encountered in chronic lung diseases such as cystic fibrosis or chronic obstructive pneumonia, as well as acute settings like mechanical ventilation acquired pneumonia or neutropenic patients. It is a major cause of mortality and morbidity in these diseases. In lungs, P. aeruginosa settles in a biofilm mode of growth with the secretion of exopolysaccharides in which it is encapsulated, enhancing its antibiotic resistance and contributing to the respiratory deficiency of patients. However, bacteria must first multiply to a high density and display a cytotoxic phenotype to avoid the host's defences. A virulence determinant implicated in this step of infection is the type III secretion system (TTSS), allowing toxin injection directly into host cells. At the beginning of the infection, most strains isolated from patients' lungs possess an inducible TTSS allowing toxins injection or secretion upon in vivo or in vitro activation signals. As the infection persists most of the bacteria permanently loose this capacity, although no mutations have been evidenced. We name "non inducible" this phenotype. As suggested by the presence of a positive feedback circuit in the regulatory network controlling TTSS expression, it may be due to an epigenetic switch allowing heritable phenotypic modifications without genotype's mutations. RESULTS: Using the generalised logical method, we designed a minimal model of the TTSS regulatory network that could support the epigenetic hypothesis, and studied its dynamics which helped to define a discriminating experimental scenario sufficient to validate the epigenetic hypothesis. A mathematical framework based on formal methods from computer science allowed a rigorous validation and certification of parameters of this model leading to epigenetic behaviour. Then, we demonstrated that a non inducible strain of P. aeruginosa can stably acquire the capacity to be induced by calcium depletion for the TTSS after a short pulse of a regulatory protein. Finally, the increased cytotoxicity of a strain after this epigenetic switch was demonstrated in vivo in an acute pulmonary infection model. CONCLUSION: These results may offer new perspectives for therapeutic strategies to prevent lethal infections by P. aeruginosa by reverting the epigenetic inducibility of type III cytotoxicity

L'agent glottopolitique et son glossaire. Enjeux de représentations des langues chez trois romanciers hétérolingues

International audienceQuand dire, c’est feindre…L’analyse des emprunts aux langues endogènes dans les romans hétérolingues génère une interrogation sur leur dimension mimétique. Si la critique linguistique et la sociocritique des littératures francophones tendent à percevoir les romans hétérolingues comme représentatifs des contextes plurilingues, en revanche les partisans de l’hétérolinguisme mettent en évidence la dimension illusoire de cette représentation. Quand dire, c’est faire...En revanche, le glossaire des écrivains hétérolingues tend à imposer en langue les emprunts, dévoilant ainsi sa portée glottopolitique. Les pratiques glossairistiques spécifiques des écrivains peuvent ainsi être mises en relation avec leurs représentations épilinguistiques déclarées, comme avec celles des locuteurs endogènes de la société dont ils émanent. L’analyse de trois romans francophones (Le Jujubier du Patriarche, d’Aminata Sow Fall, 1993, Allah n’est pas obligé, de Kourouma, 2000, et Le Rocher de Tanios, de Maalouf, 1993) révèle l’intérêt des comparaisons du glossaire des écrivains pour découvrir plus en profondeur la spécificité de leur rapport à la langue littéraire

Modelling of complex biological systems in the context of genomics: an account of a multidisciplinary thematic seminar held in Montpellier (France) in April 2005

International audienceno abstrac

Attraction Basins as Gauges of Robustness against Boundary Conditions in Biological Complex Systems

One fundamental concept in the context of biological systems on which researches have flourished in the past decade is that of the apparent robustness of these systems, i.e., their ability to resist to perturbations or constraints induced by external or boundary elements such as electromagnetic fields acting on neural networks, micro-RNAs acting on genetic networks and even hormone flows acting both on neural and genetic networks. Recent studies have shown the importance of addressing the question of the environmental robustness of biological networks such as neural and genetic networks. In some cases, external regulatory elements can be given a relevant formal representation by assimilating them to or modeling them by boundary conditions. This article presents a generic mathematical approach to understand the influence of boundary elements on the dynamics of regulation networks, considering their attraction basins as gauges of their robustness. The application of this method on a real genetic regulation network will point out a mathematical explanation of a biological phenomenon which has only been observed experimentally until now, namely the necessity of the presence of gibberellin for the flower of the plant Arabidopsis thaliana to develop normally

Introduction

Guespin Louis. Introduction. In: Langages, 19ᵉ année, n°74, 1984. Dialogue et interaction verbale, sous la direction de Louis Guespin. pp. 5-14

Les embrayeurs en discours

Guespin Louis. Les embrayeurs en discours. In: Langages, 10ᵉ année, n°41, 1976. Typologie du discours politique, sous la direction de Louis Guespin. pp. 47-78