Molecular Evolution and Functional Diversification of Fatty Acid Desaturases after Recurrent Gene Duplication in Drosophila

Frequent gene duplications in the genome incessantly supply new genetic materials for functional innovation presumably driven by positive Darwinian selection. This mechanism in the desaturase gene family has been proposed to be important in triggering the pheromonal diversification in insects. With the recent completion of a dozen Drosophila genomes, a genome-wide perspective is possible. In this study, we first identified homologs of desaturase genes in 12 Drosophila species and noted that while gene duplication events are relatively frequent, gene losses are not scarce, especially in the desat1–desat2–desatF clade. By reconciling the gene tree with species phylogeny and the chromosomal synteny of the sequenced Drosophila genomes, at least one gene loss in desat2 and a minimum of six gene gains (resulting in seven desatF homologs, α-η), three gene losses and one relocation in desatF were inferred. Upon branching off the ancestral desat1 lineage, both desat2 and desatF gained novel functions through accelerating protein evolution. The amino acid residues under positive selection located near the catalytic sites and the C-terminal region might be responsible for altered substrate selectivity between closely related species. The association between the expression pattern of desatF-α and the chemical composition of cuticular hydrocarbons implies that the ancestral function of desatF-α is the second desaturation at the four carbons after the first double bond in diene synthesis, and the shift from bisexual to female-specific expression in desatF-α occurred in the ancestral lineage of Drosophila melanogaster subgroup. A relationship between the number of expressed desatF homologs and the diene diversification has also been observed. These results suggest that the molecular diversification of fatty acid desaturases after recurrent gene duplication plays an important role in pheromonal diversity in Drosophila

Courtship Initiation Is Stimulated by Acoustic Signals in Drosophila melanogaster

Finding a mating partner is a critical task for many organisms. It is in the interest of males to employ multiple sensory modalities to search for females. In Drosophila melanogaster, vision is thought to be the most important courtship stimulating cue at long distance, while chemosensory cues are used at relatively short distance. In this report, we show that when visual cues are not available, sounds produced by the female allow the male to detect her presence in a large arena. When the target female was artificially immobilized, the male spent a prolonged time searching before starting courtship. This delay in courtship initiation was completely rescued by playing either white noise or recorded fly movement sounds to the male, indicating that the acoustic and/or seismic stimulus produced by movement stimulates courtship initiation, most likely by increasing the general arousal state of the male. Mutant males expressing tetanus toxin (TNT) under the control of Gr68a-GAL4 had a defect in finding active females and a delay in courtship initiation in a large arena, but not in a small arena. Gr68a-GAL4 was found to be expressed pleiotropically not only in putative gustatory pheromone receptor neurons but also in mechanosensory neurons, suggesting that Gr68a-positive mechanosensory neurons, not gustatory neurons, provide motion detection necessary for courtship initiation. TNT/Gr68a males were capable of discriminating the copulation status and age of target females in courtship conditioning, indicating that female discrimination and formation of olfactory courtship memory are independent of the Gr68a-expressing neurons that subserve gustation and mechanosensation. This study suggests for the first time that mechanical signals generated by a female fly have a prominent effect on males' courtship in the dark and leads the way to studying how multimodal sensory information and arousal are integrated in behavioral decision making

A Role for TLR4 in Clostridium difficile Infection and the Recognition of Surface Layer Proteins

Clostridium difficile is the etiological agent of antibiotic-associated diarrhoea (AAD) and pseudomembranous colitis in humans. The role of the surface layer proteins (SLPs) in this disease has not yet been fully explored. The aim of this study was to investigate a role for SLPs in the recognition of C. difficile and the subsequent activation of the immune system. Bone marrow derived dendritic cells (DCs) exposed to SLPs were assessed for production of inflammatory cytokines, expression of cell surface markers and their ability to generate T helper (Th) cell responses. DCs isolated from C3H/HeN and C3H/HeJ mice were used in order to examine whether SLPs are recognised by TLR4. The role of TLR4 in infection was examined in TLR4-deficient mice. SLPs induced maturation of DCs characterised by production of IL-12, TNFα and IL-10 and expression of MHC class II, CD40, CD80 and CD86. Furthermore, SLP-activated DCs generated Th cells producing IFNγ and IL-17. SLPs were unable to activate DCs isolated from TLR4-mutant C3H/HeJ mice and failed to induce a subsequent Th cell response. TLR4−/− and Myd88−/−, but not TRIF−/− mice were more susceptible than wild-type mice to C. difficile infection. Furthermore, SLPs activated NFκB, but not IRF3, downstream of TLR4. Our results indicate that SLPs isolated from C. difficile can activate innate and adaptive immunity and that these effects are mediated by TLR4, with TLR4 having a functional role in experimental C. difficile infection. This suggests an important role for SLPs in the recognition of C. difficile by the immune system

Rapid Evolution of Sex Pheromone-Producing Enzyme Expression in Drosophila

Rapid evolution of gene expression patterns responsible for pheromone production in 24 species of Drosophila was mapped to simple mutations within the regulatory domain of the desatF gene

Protéines de surface Cwp66, Cwp84, Fbp68 et protéines flagellaires FliC, FliD de Clostridium difficile (intérêt dans une stratégie vaccinale)

Clostridium difficile est une bactérie responsable de diarrhées et de colites pseudomembraneuses. Notre but était de sélectionner des protéines de surface impliquées dans la colonisation intestinale par C. difficile, afin de développer une stratégie vaccinale par voie muqueuse. Nous avons étudié les protéines flagellaires FliC, FliD et des protéines de paroi : l'adhésine Cwp66, la protéine liant la fibronectine Fbp68 et la protéase Cwp84. Les antigènes sélectionnés sont les protéines les plus immunogènes et les moins variables : FliC, FliD et Cwp84. Puis, des souris à flore humaine ont été immunisées par voie rectale, induisant une immunité systémique et muqueuse satisfaisante avec : i) les protéines flagellaires, ii) les protéines Cwp84 et FliD, iii) des extraits pariétaux de C. difficile. Une diminution significative de la colonisation du tube digestif par C. difficile a été observée chez les souris immunisées versus les souris témoins. Chez le hamster, nous avons observé un retard de mortalité des hamsters immunisés par rapport aux hamsters témoins.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Etude protéomique de sécrétome chez différentes souches de Clostridium difficile

PARIS-BIUP (751062107) / SudocSudocFranceF

Evolution et devenir à l'âge adulte des enfants soignés en hôpital de jour (réflexion à partir de l'étude de 20 trajectoires d'enfants, 14 ans en moyenne après leur sortie de l'hôpital de jour la Villa Lang à Lyon)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Intolérance et reconnaissance religieuse à Salvador de Bahia (le face-à-face des Eglises néopentecôtistes et des religions de matrice africaine en ce début de XXIe siècle)

Dans le Brésil actuel, la baisse significative de la prédominance catholique au profit notamment des Églises pentecôtistes dessine un nouveau paysage religieux. La pluralité religieuse est désormais de mise et la quête de reconnaissance couplée au prosélytisme agressif de certains ne va pas sans entraîner des conflits. À Salvador de Bahia, une intolérance religieuse s'installe et s'inscrit dans l'imaginaire symbolique de certaines Églises néopentecôtistes qui suivent une "Théologie de la guerre spirituelle". En tête de file, l'Église Universelle du Royaume de Dieu qui formule des accusations de sorcellerie à l'égard du Candomblé, posant ainsi les repères d'une "croisade contre le diable" relayée par d'importants moyens de communication. C'est la centralité de l'exorcisme, du combat contre les forces du mal qui constitue l'élément majeur de cette Église. Face à cette intolérance qui s'exprime jusque dans les actes, les religions de matrice africaine résistent, s'organisent et tentent de faire reculer la virulence des attaques. Cette controverse, écho de la pentecôtisation d'une part importante de la société -que l'on pourrait dans la précipitation associer à une guerre de religions -est porteuse d'enjeux complexes que cette thèse vise à analyserCurrently, the growing situation of pluralism and religious diversity in Brazil sets up a scenario of decrease of the Catholicism and increasing of the Pentecostal churches, it is drawing a new religious reality. The religious plurality is thus marked and the search for recognition as well as the aggressive proselytizing of some give birth to conflicts. The religious intolerance has been settled down in Salvador Bahia. This intolerance has been drawn in the symbolic imagery of neo-Pentecostal religious movements that follow the "Theology of Spiritual Warfare." As leader of the movement, the Universal Church of the Kingdom of God accuses Candomblé of practicing witchcraft, thus spreading its primary mission "of crusade against the devil" -this is broadcasted by that church's media. The elements of this "crusade" are based on the centrality of exorcism and the fighting against the evil forces. Before the acts of intolerance, the religions of African Matrix organize themselves and try to push back the virulence of the attacks. This controversy is the result of "Pentecostalization" of an important part of society is the carrier of complex issues that this thesis intends to analyze.PARIS3-BU (751052102) / SudocSudocFranceBrazilFRB