The airway microbiome and disease.

Although traditionally thought to be sterile, accumulating evidence now supports the concept that our airways harbor a microbiome. Thus far, studies have focused upon characterizing the bacterial constituents of the airway microbiome in both healthy and diseased lungs, but what perhaps provides the greatest impetus for the exploration of the airway microbiome is that different bacterial phyla appear to dominate diseased as compared with healthy lungs. As yet, there is very limited evidence supporting a functional role for the airway microbiome, but continued research in this direction is likely to provide such evidence, particularly considering the progress that has been made in understanding host-microbe mutualism in the intestinal tract. In this review, we highlight the major advances that have been made discovering and describing the airway microbiome, discuss the experimental evidence that supports a functional role for the microbiome in health and disease, and propose how this emerging field is going to impact clinical practice.

Characterization of the immunological properties of " Plasmodium falciparum " and " Plasmodium berghei " circumsporozoite proteins : antibody responses and recognition by specific CD8+ T cells

SUMMARY Interest in developing intervention strategies against malaria by targeting the liver stage of the Plasmodium life cycle has been fueled by studies which show that sterile protective immunity can be achieved by immunization with radiation-attenuated sporozoites. Anti-malarial drugs and insecticides have been widely used to control the disease, but in the hope of developing a more cost-effective intervention strategy, vaccine development has taken centre stage in malaria research. There is currently no vaccine against malaria. Attenuated sporozoite-induced immunity is achieved by antibodies and T cells against malaria liver stage antigens, the most abundant being the circumsporozoite protein (CSP), and many vaccine formulations aim at mimicking this immunity. However, the mechanisms by which the antibody and T cell immune responses are generated after infection by sporozoites, or after immunization with different vaccine formulations are still not well understood. The first part of this work aimed at determining the ability of primary hepatocytes from BALB/c mice to process and present CSP-derived peptides after infection with P. berghei sporozoites. Both infected hepatocytes and those traversed by sporozoites during migration were found to be capable of processing and presenting the CSP to specific CD8+ T cells in vitro. The pathway of processing and presentation involved the proteasome, aspartic proteases and transport through a post-Endoplasmic Reticulum (ER) compartment. These results suggest that in vivo, infected hepatocytes contribute to the elicitation and expansion of a T cell response. In the second part, the antibody responses of CB6F1 mice to synthetic peptides corresponding to the N- and C-terminal domains of P. berghei and P. falciparum CS proteins were characterized. Mice were immunized with single peptides or a combination of N- and C-terminal peptides. The peptides were immunogenic in mice and the antisera generated could recognize the native CSP on the sporozoite surface. Antisera generated against the N-terminal peptides or against the combinations inhibited sporozoite invasion of hepatocytes in vitro. In vivo, more mice immunized with single P. berghei peptides were protected from infection upon a challenge with P. berghei sporozoites, than mice immunized with a combination of N- and C-terminal peptides. Furthermore, P. falciparum N-terminal peptides were recognized by serum samples from people living in malaria-endemic areas. Importantly, recognition of a peptide from the N-terminal fragment of the P. falciparum CSP by sera from children living in a malaria-endemic region was associated with protection from disease. These results underline the potential of using such peptides as malaria vaccine candidates. RESUME L'intérêt de développer des stratégies d'intervention contre la malaria ciblant le stade pré-erythrocytaire a été alimenté par des études qui montrent qu'il est possible d'obtenir une immunité par l'injection de sporozoites irradiés. Les médicaments et les insecticides anti-paludiques ont été largement utilisés pour contrôler la maladie, mais dans l'espoir de développer une stratégie d'intervention plus rentable, le développement de vaccins a été placé au centre des recherches actuelles contre la malaria. A l'heure actuelle, il n'existe aucun vaccin contre la malaria. L'immunité induite par les sporozoites irradiés est due à l'effet combiné d'anticorps et de cellules T qui agissent contre les antigènes du stade hépatique dont le plus abondant est la protéine circumsporozoite (CSP). Beaucoup de formulations de vaccin visent à imiter l'immunité induite par les sporozoites irradiés. Cependant, les mécanismes par lesquels les anticorps et les cellules T sont génerés après infection par les sporozoites ou après immunisation avec des formulations de vaccin ne sont pas bien compris. La première partie de ce travail a visé à déterminer la capacité de hépatocytes primaires provenant de souris BALB/c à "processer" et à présenter des peptides dérivés de la CSP, après infection par des sporozoites de Plasmodium berghei. Nous avons montré que in vitro, les hépatocytes infectés et ceux traversés par les sporozoites pendant leur migration étaient capables de "processer" et de présenter la CSP aux cellules T CD8+ spécifiques. La voie de présentation implique le protéasome, les protéases de type aspartique et le transport à travers un compartiment post-reticulum endoplasmique. Ces résultats suggèrent que in vivo, les hépatocytes infectés contribuent à l'induction et à l'expansion d'une réponse immunitaire spécifique aux cellules T. Dans la deuxième partie, nous avons caractérisé les réponses anticorps chez les souris de la souche CB6F1 face aux peptides N- et C-terminaux des protéines circumsporozoites de Plasmodium berghei et Plasmodium falciparum. Les souris ont été immunisées avec les peptides individuellement ou en combinaison. Les peptides utilisés étaient immunogéniques chez les souris, et les anticorps produits pouvaient reconnaître la protéine CSP native à la surface des sporozoites. In vitro, les sera contre les peptides N-teminaux et les combinaisons étaient capables d'inhiber l'invasion de hépatocytes par les sporozoites. In vivo, plus de souris immunisées avec les peptides individuels de la CSP de P. berghei étaient protégées contre la malaria que les souris immunisées avec une combinaison de peptides N- et C-terminaux. De plus, les peptides N-terminaux de la CSP de P. falciparum ont été reconnus par les sera de personnes vivant dans des régions endémiques pour la malaria. Il est intéressant de voir que la reconnaissance d'un peptide N-terminal de P. falciparum par des sera d'enfants habitant dans des régions endémiques était associé à la protection contre la maladie. Ces résultats soulignent le potentiel de ces peptides comme candidats-vaccin contre la malaria.

Sonication of catheter tips for improved detection of microorganisms on external ventricular drains and ventriculo-peritoneal shunts.

The diagnosis of infections involving internal or external neurosurgical drainage devices is challenging, and to our knowledge no single reliable microbiological test exists. We used sonication to study bacterial colonization in 14 explanted external ventricular drains (EVD) and 13 ventriculo-peritoneal shunt (VPS) devices. This technique dislodges biofilm bacteria from the surface of implanted materials before culture. Removed devices were sonicated in saline (40 kHz, 1 minute, 0.25 W/cm(2)), the resulting fluid was cultured aerobically and anaerobically at 37°C, and bacterial growth was counted. Ventricular cerebrospinal fluid (CSF) was cultured separately. In the EVD group, sonication cultures grew significantly more bacteria (64%, 9/14) than cultures of aspirated ventricular CSF (14%, 2/14). In the VPS group the difference was not significant. Positive sonication cultures of EVD catheters yielded a median of >100 colony forming units (CFU) (range, 60-800). For positive sonication cultures of VPS, the median was 1000 CFU (range, 20-100,000). All patients with bacteria in their CSF also had positive sonication cultures from the removed device. Of the five patients with sterile or presumably contaminated CSF cultures but positive sonication cultures of removed shunts, one became afebrile after removal of the EVD, two developed meningitis and two remained asymptomatic. Sonication culture of EVD appears to improve the microbiological assessment of device-related infection and it corroborates with CSF cultures of revision surgery for VPS. Sonication of the removed EVD tip may raise awareness for the onset of meningitis.

Melt topology and chemistry during partial melting in contact aureoles : an experimental study and field example

This study was initiated to investigate partial melting within the high-grade metamorphic rocks beneath the Little Cottonwood contact aureole (Utah, USA), in order to understand the melt generation, melt migration, and geometry of initial melt distribution on grain scale during crustal anatexis. The emplacement of the Little Cottonwood stock produced a contact aureole in the pelitic host rocks of the Big Cottonwood formation (BC). Metamorphic isogrades in pelitic rocks range form biotite to 2nd sillimanite grade as a function of distance from the contact. Migmatites are restricted to the highest grade and resulted form partial melting of the BC formation rocks. First melt was produced by a combined muscovite/biotite dehydration reaction in the sillimanite + k-feldspar stability field. Melt extraction from the pelites resulted in restites (magnetite + cordierite + alumosilicate ± biotite) surrounded by feldspar enriched quartzite zones. This texture is the result of gradual infiltration of partial melts into the quartzite. Larger, discrete melt accumulation occurred in extensional or transpressional domains such as boudin necks, veins, and ductile shear zones. Melt composition are Si02- rich, crystallized as pegmatites, and apparently were very mobile. They were able to infiltrate the quartzite pervaisivly. These melts are similar in composition to first melts produced in the hydrothermal partial melt experiments at 2kbar between 700 - 800°C on fine grained high metamorphic rocks (andalusite-cordierited-biotite-zone) of the BC formation. The experimental melts are water rich and in disequilibrium with the melting rock. Initial melt composition is heterogeneous for short run duration, reflective a lack of chemical equilibrium between individual melt pools. Rock core scale heterogeneity decreased with time indicating partial homogenization of melt compositions. A simultaneous shift of melt composition to higher silica content with time was observed. The silica content of the melt increased due to local melt/mineral reactions. Melt textures indicate that reactive melt transport is most efficient along grain boundaries rimmed by dissimilar grains. Melt heterogeneity resulted in chemical potential gradients which are major driving forces for initial melt migration and govern melt distribution during initial melting. An additional subject of the thesis is the crystal size distributions of opaque minerals in a fine-grained, high-grade meta-pelite of the Big Cottonwood which were obtained from 3D X-ray tomography (uCT) and 2D thin section analysis. µCT delivers accurate size distributions within a restricted range (~ a factor of 20 in size in a single 3D image), while the absolute number of crystals is difficult to obtain from these sparsely distributed, small crystals on the basis of 2D images. Crystal size distributions obtained from both methods are otherwise similar. - Ce travail de recherche a été entrepris dans le but d'étudier les processus de fusion partielle dans les roches fortement métamorphiques de l'auréole de contact de Little Cottonwood (Utah, USA) et ceci afin de comprendre la génération de liquide de fusion, la migration de ces liquides et la géométrie de la distribution initiale des liquides de fusion à l'échelle du grain durant l'anatexie de la croûte. L'emplacement du petit massif intrusif de Little Cottonwood a produit une auréole de contact dans les roches pélitiques encaissantes appartenant à la Foimation du Big Cottonwood (BC). Les isogrades métamorphiques dans les roches pélitiques varient de l'isograde de la biotite à la deuxième isograde de la sillimanite en fonction de la distance par rapport au massif intrusif. Les migmatites sont restreintes aux zones montrant le plus haut degré métamorphique et résultent de la fusion partielle des roches de la Formation de BC. Le premier liquide de fusion a été produit par la réaction de déshydratation combinée de la muscovite et de la biotite dans le champ de stabilité du feldspath potassique Pt de la sillimanite. L'extraction du liquide de fusion des pélites forme des restites (magnétites + cordiérite + aluminosilicate ± biotite) entourées par des zones de quartzites enrichies en feldspath. Cette texture est le résultat de l'infiltration graduelle du liquide de fusion partielle dans les quartzites. Des accumulations distinctes et plus larges de liquide de fusion ont lieu dans des domaines d'extension ou de transpression tels que les boudins, les veines, et les zones de cisaillement ductile. La composition des liquides de fusion est similaire à celle des liquides pegmatoïdes, et ces liquides sont apparemment très mobiles et capables d'infiltrer les quartzites. Ces liquides de fusion ont la même composition que les premiers liquides produits dans les expériences hydrotheunales de fusion partielle à 2kbar et entre 700-800° C sur les roches finement grenues et hautement métamorphiques (andalousite-cordiérite-biotite zone) de la Formation de BC. Les liquides de fusion obtenus expérimentalement sont riches en eau et sont en déséquilibre avec la roche en fusion. La composition initiale des liquides de fusion est hétérogène pour les expériences de courte durée et reflète l'absence d'équilibre chimique entre les différentes zones d'accumulation des liquides de fusion. L'hétérogénéité à l'échelle du noyau s'estompe avec le temps et témoigne de l'homogénéisation de la composition des liquides de fusion. Par ailleurs, on observe parallèlement un décalage de la composition des liquides vers des compositions plus riches en silice au cours du temps. Le contenu en silice des liquides de fusion évolue vers un liquide pegmatitique en raison des réactions liquides/minéraux. Les textures des liquides de fusion indiquent que le transport des liquides est plus efficace le long des bordures de grains bordés par des grains différents. Aucun changement apparent du volume total n'est visible. L'hétérogénéité des liquides s'accompagne d'un gradient de potentiel chimique qui sert de moteur principal à la migration des liquides et à la distribution des liquides durant la fusion. Un sujet complémentaire de ce travail de thèse réside dans l'étude de la distribution de la taille des cristaux opaques dans les pélites finement grenues et fortement métamorphiques de la Formation de Big Cottonwood. Les distributions de taille ont été obtenues suite à l'analyse d'images 3D acquise par tomographie ainsi que par analyse de lames minces. La microtomographie par rayon X fournit une distribution de taille précise sur une marge restreinte (- un facteur de taille 20 dans une seule image 3D), alors que le nombre absolu de cristaux est difficile à obtenir sur la base d'image 2D en raison de la petite taille et de la faible abondance de ces cristaux. Les distributions de taille obtenues par les deux méthodes sont sinon similaire. Abstact: Chemical differentiation of the primitive Earth was due to melting and separation of melts. Today, melt generation and emplacement is still the dominant process for the growth of the crust. Most granite formation is due to partial melting of the lower crust, followed by transport of magma through the crust to the shallow crust where it is emplaced. Partial melting and melt segregation are essential steps before such a granitic magma can ascent through the crust. The chemistry and physics of partial melting and segregation is complex. Hence detailed studies, in which field observations yield critical information that can be compared to experimental observations, are crucial to the understanding of these fundamental processes that lead and are leading to the chemical stratification of the Earth. The research presented in this thesis is a combined field and experimental study of partial melting of high-grade meta-pelitic rocks of the Little Cottonwood contact aureole (Utah, USA). Contact metamorphic rocks are ideal for textural studies of melt generation, since the relatively short times of the metamorphic event prevents much of the recrystallization which plagues textural studies of lower crustal rocks. The purpose of the study is to characterize melt generation, identify melting reactions, and to constrain melt formation, segregation and migration mechanisms. In parallel an experimental study was undertaken to investigate melt in the high grade meta pelitic rocks, to confirm melt composition, and to compare textures of the partial molten rock cores in the absence of deformation. Results show that a pegmatoidal melt is produced by partial melting of the pelitic rocks. This melt is highly mobile. It is capable of pervasive infiltration of the adjacent quartzite. Infiltration results in rounded quartz grains bordered by a thin feldspar rim. Using computed micro X-ray tomography these melt networks can be imaged. The infiltrated melt leads to rheological weakening and to a decompaction of the solid quartzite. Such decompaction can explain the recent discovery of abundant xenocrysts in many magmas, since it favors the isolation of mineral grains. Pervasive infiltration is apparently strongly influenced by melt viscosity and melt-crystal wetting behavior, both of which depend on the water content of melt and the temperature. In all experiments the first melt is produced on grain boundaries, dominantly by the local minerals. Grain scale heterogeneity of a melting rock leads thus to chemical concentration gradients in the melt, which are the driving force for initial melt migration. Pervasive melt films along grain boundaries leading to an interconnected network are immediately established. The initial chemical heterogeneities in the melt diminish with time. Résumé large public: La différenciation chimique de la Terre primitive est la conséquence de la fusion des roches et de la séparation des liquides qui en résultent. Aujourd'hui, la production de liquide magmatique est toujours le mécanisme dominant pour la croissance de la croûte terrestre. Ainsi la formation de la plupart des granites est un processus qui implique la production de magma par fusion partielle de la croûte inférieure, la migration de ces magmas à travers la croûte et finalement son emplacement dans les niveaux superficielle de la croûte terrestre. Au cours de cette évolution, les processus de fusion partielle et de ségrégation sont des étapes indispensables à l'ascension des granites à travers la croûte. Les conditions physico-chimiques nécessaires à la fusion partielle et à l'extraction de ces liquides sont complexes. C'est pourquoi des études détaillées des processus de fusion partielle sont cruciales pour la compréhension de ces mécanismes fondamentaux responsables de la stratification chimique de la Terre. Parmi ces études, les observations de terrain apportent notamment des informations déterminantes qui peuvent être comparées aux données expérimentales. Le travail de recherche présenté dans ce mémoire de thèse associe études de terrain et données expérimentales sur la fusion partielle des roches pélitiques de haut degré métamorphiques provenant de l'auréole de contact de Little Cottonwood (Utah, USA). Les roches du métamorphisme de contact sont idéales pour l'étude de la folination de liquide de fusion. En effet, la durée relativement courte de ce type d'événement métamorphique prévient en grande partie la recristallisation qui perturbe les études de texture des roches dans la croûte inférieure. Le but de cette étude est de caractériser la génération des liquides de fusion, d'identifier les réactions responsables de la fusion de ces roches et de contraindre la formation de ces liquides et leur mécanisme de ségrégation et de migration. Parallèlement, des travaux expérimentaux ont été entrepris pour reproduire la fusion partielle de ces roches en laboratoire. Cette étude a été effectuée dans le but de confirmer la composition chimique des liquides, et de comparer les textures obtenues en l'absence de déformation. Les résultats montrent qu'un liquide de fusion pegmatoïde est produit par fusion partielle des roches pélitiques. La grande mobilité de ce liquide permet une infiltration pénétrative dans les quarzites. Ces infiltrations se manifestent par des grains de quartz arrondis entourés par une fine bordure de feldspath. L'utilisation de la tomography à rayons X a permis d'obtenir des images de ce réseau de liquide de fusion. L'infiltration de liquide de fusion entraîne un affaiblissement de la rhéologie de la roche ainsi qu'une décompaction des quartzites massifs. Une telle décompaction peut expliquer la découverte récente d'abondants xénocristaux dans beaucoup de magmas, puisque elle favorise l'isolation des minéraux. L'infiltration pénétrative est apparemment fortement influencée par la viscosité du fluide de fusion et le comportement de la tension superficielle entre les cristaux et le liquide, les deux étant dépendant du contenu en eau dans le liquide de fusion et de la température. Dans toutes les expériences, le premier liquide est produit sur les bordures de grains, principalement par les minéraux locaux. L'hétérogénéité à l'échelle des grains d'une roche en fusion conduit donc à un gradient de concentration chimique dans le liquide, qui sert de moteur à l'initiation de la migration du liquide. Des fines couches de liquide de fusion le long de bordures de grains formant un réseau enchevêtré s'établit immédiatement. Les hétérogénéités chimiques initiales dans le liquide s'estompent avec le temps.

Effects of ploidy and sex-locus genotype on gene expression patterns in the fire ant Solenopsis invicta.

Males in many animal species differ greatly from females in morphology, physiology and behaviour. Ants, bees and wasps have a haplodiploid mechanism of sex determination whereby unfertilized eggs become males while fertilized eggs become females. However, many species also have a low frequency of diploid males, which are thought to develop from diploid eggs when individuals are homozygous at one or more sex determination loci. Diploid males are morphologically similar to haploids, though often larger and typically sterile. To determine how ploidy level and sex-locus genotype affect gene expression during development, we compared expression patterns between diploid males, haploid males and females (queens) at three developmental timepoints in Solenopsis invicta. In pupae, gene expression profiles of diploid males were very different from those of haploid males but nearly identical to those of queens. An unexpected shift in expression patterns emerged soon after adult eclosion, with diploid male patterns diverging from those of queens to resemble those of haploid males, a pattern retained in older adults. The finding that ploidy level effects on early gene expression override sex effects (including genes implicated in sperm production and pheromone production/perception) may explain diploid male sterility and lack of worker discrimination against them during development.

Experimental bacterial endocarditis after dental extractions in rats with periodontitis.

The development of bacterial endocarditis was analyzed after dental extractions in rats with or without periodontal disease. Periodontal disease was produced in rats by tying silk ligatures around the two maxillary first molars and placing the animals on a high sucrose diet for 14 weeks. Sterile aortic valve vegetations were produced by means of a transaortic catheter, and 24 hr later the maxillary first molars were extracted. The animals were killed 72 hr after the extractions. In rats with periodontal disease, extractions resulted in a 48% (14 of 29) incidence of bacterial endocarditis, most cases of which were due to Streptococcus spp. (one was caused by Staphylococcus aureus). In contrast, when the teeth with a healthy periodontium were extracted, only 6% (one of 15) of the rats developed endocarditis. When catheters were placed in animals with periodontal disease but no extractions were performed, no endocarditis occurred.

Vitellogenin Underwent Subfunctionalization to Acquire Caste and Behavioral Specific Expression in the Harvester Ant Pogonomyrmex barbatus.

The reproductive ground plan hypothesis (RGPH) proposes that the physiological pathways regulating reproduction were co-opted to regulate worker division of labor. Support for this hypothesis in honeybees is provided by studies demonstrating that the reproductive potential of workers, assessed by the levels of vitellogenin (Vg), is linked to task performance. Interestingly, contrary to honeybees that have a single Vg ortholog and potentially fertile nurses, the genome of the harvester ant Pogonomyrmex barbatus harbors two Vg genes (Pb_Vg1 and Pb_Vg2) and nurses produce infertile trophic eggs. P. barbatus, thus, provides a unique model to investigate whether Vg duplication in ants was followed by subfunctionalization to acquire reproductive and non-reproductive functions and whether Vg reproductive function was co-opted to regulate behavior in sterile workers. To investigate these questions, we compared the expression patterns of P. barbatus Vg genes and analyzed the phylogenetic relationships and molecular evolution of Vg genes in ants. qRT-PCRs revealed that Pb_Vg1 is more highly expressed in queens compared to workers and in nurses compared to foragers. By contrast, the level of expression of Pb_Vg2 was higher in foragers than in nurses and queens. Phylogenetic analyses show that a first duplication of the ancestral Vg gene occurred after the divergence between the poneroid and formicoid clades and subsequent duplications occurred in the lineages leading to Solenopsis invicta, Linepithema humile and Acromyrmex echinatior. The initial duplication resulted in two Vg gene subfamilies preferentially expressed in queens and nurses (subfamily A) or in foraging workers (subfamily B). Finally, molecular evolution analyses show that the subfamily A experienced positive selection, while the subfamily B showed overall relaxation of purifying selection. Our results suggest that in P. barbatus the Vg gene underwent subfunctionalization after duplication to acquire caste- and behavior- specific expression associated with reproductive and non-reproductive functions, supporting the validity of the RGPH in ants.

Social Dynamics in Paper Wasps: The case of nest-drifting in Polistes canadensis

Le passage de la vie solitaire à la vie sociale représente une des principales transitions évolutives. La socialité a évolué au sein de plusieurs taxons du règne animal et notamment chez les insectes sociaux qui ont atteint son niveau le plus élevé : l'eusocialité. Les colonies d'insectes sociaux se composent d'une reine, qui monopolise la reproduction, et d'ouvrières, non-reproductrices ou parfois stériles, qui aident à élever la descendance de la reine. Selon la théorie de la sélection de parentèle, les ouvrières augmentent leur fitness (succès reproducteur) non pas à travers leur propre progéniture, mais en aidant des individus apparentés (leur reine) à produire davantage de descendants. Cette théorie prédit ainsi que les ouvrières ont un intérêt à rester fidèles à leur nid natal. Toutefois, chez la guêpe tropicale Polistes canadensis, de nombreuse ouvrières visitent d'autres nids que leur nid natal : un phénomène appelé « dérive des ouvrières ». Le but de ce doctorat est ainsi de mieux comprendre les mécanismes impliqués dans ce comportement particulier des ouvrières ainsi que ces implications pour la théorie de la sélection de parentèle. Nous avons examiné le comportement de dérive des ouvrières à travers une étude des dynamiques sociales chez la guêpe tropicale P. canadensis. Mes résultats montrent que les populations de P. canadensis se composent en différentes agrégations de nids. Malgré de précédentes suggestions, on n'observe qu'une faible viscosité génétique au sein des populations de P. canadensis étudiées. On retrouve toutefois un degré d'apparentement entre nids d'une même agrégation. Ceci suggère que les ouvrières dériveuses sont susceptibles de bénéficier de fitness indirect en aidant les nids proches géographiquement. De plus, ces échanges d'ouvrières ne semblent pas accidentels puisque l'on constate des variations de taux de dérive et puisque les déplacements observés entre nids persistent sur plusieurs périodes de temps. La charge de travail, qui correspond aux différences d'effort de fourragement entre nid visités et natals, est décrite dans notre étude comme potentiel facteur expliquant le comportement de dérive des ouvrières chez P. canadensis. Nos expériences de retrait d'ouvrières et de couvain ont révélées que les dériveuses ne semblent pas répondre aux changements de besoins en aide des nids visités. Les ouvrières dériveuses biaisent leur effort en aidant leur propre nid, par lequel elles bénéficient le plus en termes de fitness indirect, avant de se consacrer à tout autre nid. Dans l'ensemble, ces résultats sur la dérive des ouvrières chez P. canadensis sont cohérents et suggèrent que ce comportement est une importante stratégie de reproduction alternative chez cette espèce qui contribue à la fitness indirecte de ces ouvrières non-reproductrices. De plus, ce doctorat apporte des informations sur la structure génétique des populations de guêpes Polistes et décrit le rôle des ouvrières inactives. Celles-ci semblent servir de réserve en ouvrières apportant du support à la colonie dans l'éventualité d'une perte d'individus. Plus généralement, ce travail met l'accent sur l'organisation complexe et l'adaptabilité des individus dans les sociétés d'insectes. - One major transition in evolution is the shift from solitary to social life. Sociality has evolved in a few taxa of the animal kingdom, most notably in the social insects which have achieved the highest level of sociality: eusociality. Colonies of social insects are formed by a reproductive queen, and many non-reproductive or sterile workers who help raise their mother queen's offspring. Kin selection theory explains worker behaviour in terms of the indirect fitness they gain from raising non-offspring kin. It therefore predicts that workers should stay faithful to their natal nests, to which they are the more related. However, in the tropical paper wasps Polistes canadensis, high levels of nest-drifting, whereby workers spend time on other neighbouring nests, has been reported. This PhD aimed at understanding the mechanisms involved in this peculiar behaviour as well as its implications for kin selection theory. I examined nest-drifting through the study of the social dynamics of the tropical paper wasp P. canadensis. My results showed that populations of this species of paper wasps are composed of different aggregations of nests. The studied populations showed little limited dispersal (viscosity), despite previous suggestion, but nests within these aggregations were more related to each other than nests outside of aggregations. This suggested that drifters may benefit from indirect fitness when helping on neighbouring nests. Drifting was unlikely to be accidental since we found drifting patterns at various rates and consistently over several time periods during monitoring. Workload (differences in colony-level foraging effort) was also a potential factor explaining nest-drifting in P. canadensis. Worker and brood removal experiments revealed that drifters do not respond to any changes in the need for help in the non-natal nests they visit. Drifters thus bias their help in their natal nests, from which they may benefit the most in terms of indirect fitness, before investing in others. Altogether, these results on nest-drifting in P. canadensis are consistent and suggest that nest-drifting is an important alternative reproductive strategy, contributing to the indirect fitness benefits gained by non-reproductive wasps. Additionally, this PhD provides information on the genetic structure of paper wasps' populations and demonstrates the role of inactive or lazy wasps as a "reserve worker force", which provides resilience to the colony in the event of worker mortality. More generally, this work further highlights the complex organization and adaptability of individuals in insect societies.

Rethinking the triggering inflammatory processes of chronic periaortitis.

Chronic periaortitis (CP) is an uncommon inflammatory disease which primarily involves the infrarenal portion of the abdominal aorta. However, CP should be regarded as a generalized disease with three different pathophysiological entities, namely idiopathic retroperitoneal fibrosis (RPF), inflammatory abdominal aortic aneurysm and perianeurysmal RPF. These entities share similar histopathological characteristics and finally will lead to fibrosis of the retroperitoneal space. Beside fibrosis, an infiltrate with variable chronic inflammatory cell is present. The majority of these cells are lymphocytes and macrophages as well as vascular endothelial cells, most of which are HLA-DR-positive. B and T cells are present with a majority of T cells of the T-helper phenotype. Cytokine gene expression analysis shows the presence of interleukin (IL)-1alpha, IL-2, IL-4, interferon-gamma and IL-2 receptors. Adhesion molecules such as E-selectin, intercellular adhesion molecule-1 and the vascular cell adhesion molecule-1 were also found in aortic tissue, and may play a significant role in CP pathophysiology. Although CP pathogenesis remains unknown, an exaggerated inflammatory response to advanced atherosclerosis (ATS) has been postulated to be the main process. Autoimmunity has also been proposed as a contributing factor based on immunohistochemical studies. The suspected allergen may be a component of ceroid, which is elaborated within the atheroma. We review the pathogenesis and the pathophysiology of CP, and its potential links with ATS. Clinically relevant issues are summarized in each section with regard to the current working hypothesis of this complex inflammatory disease.

Angioinvasive lymphomatoid papulosis: a new variant simulating aggressive lymphomas.

Lymphomatoid papulosis (LyP) belongs to the spectrum of primary cutaneous CD30-positive lymphoproliferative disorders. Clinically, LyP is characterized by a variable number of self-healing papulo-nodular lesions, with the typical waxing and waning course. Histologically, 4 types (A, B, C, and D) have been delineated. Angioinvasive growth and large ulcers are rare findings in LyP and simulate aggressive lymphoma. We retrospectively analyzed the clinicopathologic and molecular features of angioinvasive LyP in a series of 16 patients. This new form of LyP is characterized by oligolesional papules that rapidly ulcerate and evolve into large necrotic eschar-like lesions with a diameter of 1 to 4 cm and an angiocentric and angiodestructive infiltrate of small-sized to medium-sized atypical lymphocytes expressing CD30 and frequently CD8. As in other forms of LyP, the lesions underwent spontaneous regression after a few weeks. Recurrences were common, but the prognosis was excellent with no extracutaneous spread or disease-related deaths. Complete remission occurred in 9 of 16 patients (56%). This LyP variant should be distinguished from aggressive forms of angiocentric and angiodestructive and cytotoxic T-cell lymphomas. We propose the term LyP type E for this clinically and histologically unusual variant.

Improved detection of microbial ureteral stent colonisation by sonication.

PURPOSE: The diagnosis of microbial ureteral stent colonisation (MUSC) is difficult, since routine diagnostic techniques do not accurately detect microorganisms embedded in biofilms. New methods may improve diagnostic yield and understanding the pathophysiology of MUSC. The aim of the present study was to evaluate the potential of sonication in the detection of MUSC and to identify risk factors for device colonisation. METHODS: Four hundred and eight polyurethane ureteral stents of 300 consecutive patients were prospectively evaluated. Conventional urine culture (CUC) was obtained prior to stent placement and device removal. Sonication was performed to dislodge adherent microorganisms. Data of patient sex and age, indwelling time and indication for stent placement were recorded. RESULTS: Sonicate-fluid culture detected MUSC in 36%. Ureteral stents inserted during urinary tract infection (UTI) were more frequently colonised (59%) compared to those placed in sterile urine (26%; P < 0.001). Female sex (P < 0.001) and continuous stenting (P < 0.005) were significant risk factors for MUSC; a similar trend was observed in patients older than 50 years (P = 0.16). MUSC and indwelling time were positively correlated (P < 0.005). MUSC was accompanied by positive CUC in 36%. Most commonly isolated microorganisms were Coagulase-negative staphylococci (18.3%), Enterococci (17.9%) and Enterobacteriaceae (16.9%). CONCLUSIONS: Sonication is a promising approach in the diagnosis of MUSC. Significant risk factors for MUSC are UTI at the time of stent insertion, female sex, continuous stenting and indwelling time. CUC is a poor predictor of MUSC. The clinical relevance of MUSC needs further evaluation to classify isolated microorganism properly as contaminants or pathogens.

Single loci with major effects in fire ants : the effects of the complementary sex-determining locus and the green beard supergene on gene expression

Etant données la complexité et la redondance des réseaux de gènes influençant de nombreux phénotypes, l'étude des rares cas d'un locus unique ayant des effets importants sur de nombreux phénotypes peut fournir des informations cruciales sur l'évolution des traits complexes. Nous avons séquencé le génome de la fourmi de feu Solenopsis invicta pour étudier comment l'expression des gènes détermine les effets majeurs et étendus de deux loci uniques sur le phénotype. Le premier locus concerne la détermination du sexe par le modèle des allèles complémentaires. Ce locus est connu pour déterminer le sexe chez tous les hyménoptères mais n'a été caractérisé que chez les abeilles. Les hétérozygotes pour ce locus se développent en reines diploïdes (ou ouvrières stériles) alors que les homozygotes se développent en mâles diploïdes incapables de produire du sperme et les hémizygotes en mâles haploïdes fertiles. Nous avons comparé l'expression des gènes entre les reines et les deux types de mâles au stade pupe, ainsi que 1 et 11 jours après l'émergence. Nous avons trouvé un changement prononcé de l'expression des gènes chez les mâles diploïdes, passant de très proche de celle des reines au stade pupe à identique aux mâles haploïdes 11 jours après l'émergence. Cela signifie que les mâles diploïdes sont condamnés à être stériles parce que les effets après émergence du locus de détermination du sexe ne per¬mettent pas d'effacer les effets de la ploïdie sur l'expression des gènes pendant le stade pupe, quand la spermatogénèse prend place. Le second locus aux effets majeurs que nous avons étudié est le supergène dit "green beard", qui consiste en 616 gènes couvrant 55% d'un chromosome (13 Mb) et est caractérisé par une absence de recombinaison entre les deux variants du supergène : "Social B" et "Social b" (SB et Sb). Au travers de l'effet "green beard", par lequel les ouvrières avec le supergène Sb discriminent favorablement les reines qui partagent ce supergène de façon perceptible, le génotype des reines fondatrices au niveau de ce supergène détermine l'organisation de la colonie : soit elle contient une seule reine SB/SB, soit plusieurs reines SB/Sb. Nous avons montré que le chromosome Sb a évolué comme le chromosome Y, accumulant probablement des allèles favorables dans des colonies avec plusieurs reines mais défavorables dans des colonies avec une seule reine (cf. gènes sexuellement antagonistes), ainsi que des transposons et des séquences répéti¬tives. Nous avons également montré que le polymorphisme du supergène cause de grandes différences d'expression chez les ouvrières et particulièrement les reines mais pas chez les mâles. Pour comprendre comment le polymorphisme du supergène chez les reines peut affecter l'organisation de la colonie, nous avons comparé l'expression entre les génotypes SB/SB et SB/Sb chez des reines vierges (1 et 11 jours) et des reines matures. Nous avons montré que les reines SB/SB sur-régulent des gènes impliqués dans la reproduction, expli-quant pourquoi elle grandissent plus rapidement et peuvent fonder des colonies de façon indépendante, tandis que les reines SB/Sb (qui ne peuvent fonder une nouvelle colonie) sur-régulent des gènes de signalement chimique qui affectent l'organisation des colonies par l'effet "green beard". - Given the complexity and redundancy of the gene networks that underlie many pheno- types, the study of rare cases of a single locus having major effects on many phenotypes can give powerful insights into the evolution of complex traits. We sequenced the genome of Solenopsis invicta fire ants to study how gene expression mediates the widespread major effects of two single loci on phenotype. The first is the complementary sex-determining locus, which is known to exist in most Hymenoptera despite being characterized only for honeybees. Heterozygotes at this locus become diploid queens (or sterile workers), homozy¬gotes become aspermic diploid males, and hemizygotes become fertile haploid males. We compared gene expression between queens and both types of males in pupae and 1 and 11 days after eclosion. We found a pronounced shift in gene expression in diploid males, from being nearly identical to queens as pupae to identical to haploid males 11 days after eclosion. This means that diploid males are condemned to sterility because the overriding effects of the sex locus after eclosion cannot undo the ploidy effects on expression during the pupal stage, when spermatogenesis must be completed. The second locus with major ef¬fects that we studied was the so-called "green beard" supergene, which consists of 616 genes encompassing 55% of one chromosome (13 Mb), without recombination between the two variants "Social B" and "Social b" (SB and Sb) supergene. Through the green beard effect, i.e. workers with the Sb supergene discriminating in favor of queens who perceptibly share this supergene, the founding queen's genotype at the supergene determines colony organi¬zation: either headed by a single SB/SB queen or many SB/Sb queens. We show that the Sb chromosome evolved like a Y-chromosome, probably accumulating alleles beneficial in multi-queen colonies but disadvantageous in single-queen colonies (cf. sexually antagonistic genes), as well as transposons and repetitive sequences. We also show that the polymor¬phism of the supergene causes widespread expression differences in workers and especially queens but not in males. To understand how the polymorphism at the supergene in queen can transform colony organization, we compared the expression between SB/SB and SB/Sb virgin queens (1 and 11 days) and mother queens. We show that SB/SB queens up-regulate genes involved in reproduction, explaining why they mature faster and can found colonies independently, while SB/Sb queens (which cannot found colonies) up-regulate chemical signaling genes that can transform colonies through the green beard effect.

Adenovirus-mediated gene transfer into selected liver segments using a vascular exclusion technique.

Adenovirus-mediated gene therapy is hampered by severe virus-related toxicity, especially to the liver. The aim of the present study was to test the ability of a vascular exclusion technique to achieve transgene expression within selected liver segments, thus minimizing both viral and transgene product toxicity to the liver. An E1-E3-deleted replication-deficient adenovirus expressing a green fluorescent protein (GFP) reporter gene was injected into the portal vein of BDIX rats, with simultaneous clamping of the portal vein tributaries to liver segments II, III, IV, V, and VIII. GFP expression and inflammatory infiltrate were measured in the different segments of the liver and compared with those of the livers of animals receiving the viral vector in the portal vein without clamping. The GFP expression was significantly higher in the selectively perfused segments of the liver as compared with the non-perfused segments (p < 0.0001) and with the livers of animals that received the vector in the portal vein without clamping (p < 0.0001). Accordingly, the inflammatory infiltrate was more intense in the selectively perfused liver segments as compared with all other groups (p < 0.0001). Fluorescence was absent in lungs and kidneys and minimal in spleen. The clinical usefulness of adenovirus-mediated gene transfer to the liver largely depends on the reduction of its liver toxicity. Clamping of selected portal vein branches during injection allows for delivery of genes of interest to targeted liver segments. Transgene expression confined to selected liver segments may be useful in the treatment of focal liver diseases, including metastases.

Association of BAFF/BLyS overexpression and altered B cell differentiation with Sjögren's syndrome.

BAFF (BLyS, TALL-1, THANK, zTNF4) is a member of the TNF superfamily that specifically regulates B lymphocyte proliferation and survival. Mice transgenic (Tg) for BAFF develop an autoimmune condition similar to systemic lupus erythematosus. We now demonstrate that BAFF Tg mice, as they age, develop a secondary pathology reminiscent of Sjögren's syndrome (SS), which is manifested by severe sialadenitis, decreased saliva production, and destruction of submaxillary glands. In humans, SS also correlates with elevated levels of circulating BAFF, as well as a dramatic upregulation of BAFF expression in inflamed salivary glands. A likely explanation for disease in BAFF Tg mice is excessive survival signals to autoreactive B cells, possibly as they pass through a critical tolerance checkpoint while maturing in the spleen. The marginal zone (MZ) B cell compartment, one of the enlarged B cell subsets in the spleen of BAFF Tg mice, is a potential reservoir of autoreactive B cells. Interestingly, B cells with an MZ-like phenotype infiltrate the salivary glands of BAFF Tg mice, suggesting that cells of this compartment potentially participate in tissue damage in SS and possibly other autoimmune diseases. We conclude that altered B cell differentiation and tolerance induced by excess BAFF may be central to SS pathogenesis.

Cancers cutanés envahissant la base du crâne [Skin cancers infiltrating the skull base].

Squamous cell and basocellular carcinoma of the face have an excellent prognosis. Nevertherless, a small proportion therefore of these cancers differs by a much more aggressive behavior, caracterised by a tendency to infiltrate the deep facial soft tissues and facial bones. The invasion of the craniofacial skeleton and the intracranial structures follows the embryonic fusion lines or the facial sensitive or motor nerves, sometimes years after the initial treatment. The development of craniofacial surgery, reconstruction techniques and conformational radiotherapy allows us now to offer curative guided treatments, for these advanced staged tumors with a remaining limited prognosis. A therapeutic benefit implies a rigorous selection of these patients.