Construction of Pseudomonas strains with improved biocontrol activity

Selected strains of fluorescent pseudomonads suppress various plant diseases caused by soil-borne pathogenic fungi, by a blend of several mechanisms including aggressive root colonization, antibiosis, competition for nutrients, induction of resistance in the plant, and enzymatic attack of the pathogen. These traits are amenable to genetic analysis and, therefore, to modification by genetic engineering. Biocontrol activities of Pseudomonas spp. have been enhanced in two ways: (i) by overexpression of traits known to involved in diseaese suppression, and (ii) by introduction of additional beneficial traits into strains having basal biocontrol activities. Under experimental conditions in microcosms, a number of genetically modified Pseudomonas strains have given promising results. It remains to be seen whether such strains will be superior to the best naturally occurring strains, applied singly or in combination, under greenhouse and field conditions.

Why human islets die? analysis of death signaling pathways during isolation and following cytokine treatments

RESUME Le diabète de type 1 se définit comme un désordre métabolique d'origine auto-immune qui aboutit à la destruction progressive et sélective de la cellule ß-pancréatique sécrétrice d'insuline. Cette maladie représente 10 % des cas de diabète enregistrés dans la population mondiale, et touche les jeunes de moins de 20 ans. Le traitement médical par insulinothérapie corrige le manque d'hormone mais ne prévient pas les nombreuses complications telles que les atteintes cardiaques, neurologiques, rénales, rétiniennes, et les amputations que la maladie provoque. Le remplacement de la cellule ß par transplantation d'îlots de Langerhans est une alternative prometteuse au traitement médical du diabète de type 1. Cependant la greffe d'îlots est encore un traitement expérimental et ne permet pas un contrôle efficace de la glycémie au long terme chez les patients transplantés, et les raisons de cet échec restent mal comprises. L'obstacle immédiat qui se pose est la purification d'un nombre suffisant d'îlots viables et la perte massive de ces îlots dans les premières heures suite à la greffe. Cette tendance presque systématique de la perte fonctionnelle du greffon immédiatement après la transplantation est connue sous le terme de « primary graft non-function » (PNF). En effet, la procédure d'isolement des îlots provoque la destruction des composantes cellulaires et non cellulaires du tissu pancréatique qui jouent un rôle déterminant dans le processus de survie de l'îlot. De plus, la transplantation elle-même expose les cellules à différents stress, notamment le stress par les cytokines inflammatoires qui encourage la mort cellulaire par apoptose et provoque par la suite le rejet de la greffe. L'ensemble de ces mécanismes aboutit a une perte de la masse d'îlot estimée a plus de 60%. Dans ce contexte, nous nous sommes intéressés à définir les voies majeures de stress qui régissent cette perte massive d'îlot par apoptose lors du processus d'isolement et suite à l'exposition immédiate aux cytokines. L'ensemble des résultats obtenus indique que plusieurs voies de signalisation intracellulaire sont recrutées qui s'activent de manière maximale très tôt lors des premières phases de l'isolement. La mise en culture des îlots deux jours permet aux voies activées de revenir aux taux de base. De ce fait nous proposons une stratégie dite de protection qui doit être 1) initiée aussitôt que possible lors de l'isolement des îlots pancréatiques, 2) devrait probablement bloquer l'activation de ces différentes voies de stress mis en évidence lors de notre étude et 3) devrait inclure la mise en culture des îlots purifiés deux jours après l'isolement et avant la transplantation. RESUME LARGE PUBLIC Le diabète est une maladie qui entraîne un taux anormalement élevé de sucre (glucose) dans le sang du à une insuffisance du pancréas endocrine à produire de l'insuline, une hormone qui régule la glycémie (taux de glucose dans le sang). On distingue deux types majeurs de diabètes; le diabète de type 1 ou juvénile ou encore appelé diabète maigre qui se manifeste souvent pendant l'enfance et qui se traduit par une déficience absolue en insuline. Le diabète de type 2 ou diabète gras est le plus fréquent, et touche les sujets de plus de 40 ans qui souffrent d'obésité et qui se traduit par une dysfonction de la cellule ß avec une incapacité à réguler la glycémie malgré la production d'insuline. Dans le diabète de type 1, la destruction de la cellule ß est programmée (apoptose) et est majoritairement provoquée par des médiateurs inflammatoires appelés cytokines qui sont produites localement par des cellules inflammatoires du système immunitaire qui envahissent la cellule ß-pancréatiques. Les cytokines activent différentes voies de signalisation parmi lesquelles on distingue celles des Mitogen-Activated Protein Kinase (MAPKs) composées de trois familles de MAPKs: ERK1/2, p38, et JNK, et la voie NF-κB. Le traitement médical par injections quotidiennes d'insuline permet de contrôler la glycémie mais ne prévient pas les nombreuses complications secondaires liées à cette maladie. La greffe d'îlots de Langerhans est une alternative possible au traitement médical, considérée avantageuse comparée a la greffe du pancréas entier. En effet l'embolisation d'îlots dans le foie par injection intraportale constitue une intervention simple sans complications majeures. Néanmoins la technique de préparation d'îlots altère la fonction endocrine et cause la perte massive d'îlots pancréatiques. De plus, la transplantation elle-même expose la cellule ß à différents stress, notamment le stress par les cytokines inflammatoires qui provoque le rejet de greffon cellulaire. Dans la perspective d'augmenter les rendements des îlots purifiés, nous nous sommes intéressés à définir les voies majeures de stress qui régissent cette perte massive d'îlot lors du processus d'isolement et suite à l'exposition immédiate aux cytokines après transplantation. L'ensemble de ces résultats indique que le stress induit lors de l'isolement des îlots et celui des cytokines recrute différentes voies de signalisation intracellulaire (JNK, p38 et NF-κB) qui s'additionnent entre-elles pour altérer la fonction et la viabilité de l'îlot. De ce fait une stratégie doit être mise en place pour bloquer toute action synergique entre ces différentes voies activées pour améliorer la viabilité et la fonction de la cellule ß lors du greffon cellulaire. SUMMARY Type 1 diabetes mellitus (T1DM) is an autoimmune disease characterized by the progressive and selective destruction of the pancreatic ß-cells that secrete insulin, leading to absolute insulin deficiency. T1DM accounts for about 10% of all diabetes cases, affecting persons younger than 20 years of age. Medical treatment using daily exogenous insulin injection corrects hormone deficiency but does not prevent devastating complications such as heart attack, neuropathy, kidney failure, blindness, and amputation caused by the disease. Pancreatic islet transplantation (PIT) is one strategy that holds promise to cure patients with T1DM, but purified pancreatic islet grafts have failed to maintain long-term glucose homeostasis in human recipients, the reasons for this failure being still poorly understood. There is however a more immediate problem with islet grafting that is dependent upon poor islet recovery from donors and early islet loss following the first hours of grafting. This tendency of islet grafts to fail to function within a short period after transplantation is termed primary graft non-function (PNF). Indeed, the islet isolation procedure itself destroys cellular and non-cellular components of the pancreas that may play a role in supporting islet survival. Further, islet transplantation exposes cells to a variety of stressful stimuli, notably pro-inflammatory cytokines that encourage ß-cell death by apoptosis and lead to early graft failure. Altogether these mechanisms lead to an estimated loss of 60% of the total islet mass. Here, we have mapped the major intracellular stress signaling pathways that may mediate human islet loss by apoptosis during isolation and following cytokine attack. We found that several stress pathways are maximally activated from the earliest stages of the isolation procedure. Culturing islet for two days allow for the activated pathways to return to basal levels. We propose that protective strategies should 1) be initiated as early as possible during isolation of the islets, 2) should probably target the activated stress pathways that we uncovered during our studies and 3) should include culturing islets for two days post-isolation and prior transplantation.

Predicting root defence against herbivores during succession

P>1. Root herbivores and pathogens interfere with basic below-ground plant function, and can thereby affect plant fitness and spatial and temporal patterns in natural plant communities. However, there has been little development of concepts and theories on below-ground plant defence, a deficit that is in contrast to the abundance of theorizing for above-ground plant parts.2. A review of the past 10 years of research on below-ground plant-herbivore interactions has revealed that, similar to above-ground tissues, root defences can be expressed constitutively or induced upon herbivore attack, and can be classified into direct and indirect traits, tolerance, and escape. Indeed, it has been shown that roots tolerate herbivory by outgrowing or re-growing lost tissues, or resist it by producing secondary metabolites that are toxic to herbivores or attract natural enemies of herbivores.3. We propose that, similar to above-ground plant-herbivore theories, the partition of abiotic and biotic factors over ecological succession can serve as the basis for predicting investment in defence strategies below-ground.4. Investigation of herbivore pressure and root responses along primary and secondary successional gradients suggests that: (i) roots are often fast growing, thinner and softer in early compared to later succession. (ii) Insect and nematode herbivore pressure increases until mid-succession and later decreases. (iii) Mycorrhizal abundance increases with succession, and the composition of fungal species changes through succession, often shifting from arbuscular mycorrhizae to ecto-mycorrhizae.5. Based on these findings, and on classical (above-ground) plant defence theory, we suggest the following set of testable hypotheses for below-ground plant defence: (i) During succession, early plants invest most of their resources in growth and less in defences (associated with a general lack of herbivores and pathogens, and with limited availability of resources in the system), therefore relying more on re-growth (tolerance) strategies. (ii) During mid-succession, a buildup of herbivore pressure facilitates replacement by plant species that exhibit greater direct and indirect defence strategies. (iii) Constitutive and inducible levels of defences may trade-off, and early successional plants should rely more on induction of defences after herbivore attack, whereas late successional plants will increasingly rely on constitutively produced levels of physical and chemical defence. (iv) Successional changes in microbial associations have consequences for root defence by improving plant nutrition and defence expression as well as directly competing for root space; however, toxic or impenetrable root defences may also limit association with root symbionts, and so may constrain the expression of root defence.

8

Plants naturally produce the lipid-derived polyester cutin, which is found in the plant cuticle that is deposited at the outermost extracellular matrix of the epidermis covering nearly all aboveground tissues. Being at the interface between the cell and the external environment, cutin and the cuticle play important roles in the protection of plants from several stresses. A number of enzymes involved in the synthesis of cutin monomers have recently been identified, including several P450s and one acyl-CoA synthetase, thus representing the first steps toward the understanding of polyester formation and, potentially, polyester engineering to improve the tolerance of plants to stresses, such as drought, and for industrial applications. However, numerous processes underlying cutin synthesis, such as a controlled polymerization, still remain elusive. Suberin is a second polyester found in the extracellular matrix, most often synthesized in root tissues and during secondary growth. Similar to cutin, the function of suberin is to seal off the respective tissue to inhibit water loss and contribute to resistance to pathogen attack. Being the main constituent of cork, suberin is a plant polyester that has already been industrially exploited. Genetic engineering may be worth exploring in order to change the polyester properties for either different applications or to increase cork production in other species. Polyhydroxyalkanoates (PHAs) are attractive polyesters of 3-hydroxyacids because of their properties as bioplastics and elastomers. Although PHAs are naturally found in a wide variety of bacteria, biotechnology has aimed at producing these polymers in plants as a source of cheap and renewable biodegradable plastics. Synthesis of PHA containing various monomers has been demonstrated in the cytosol, plastids, and peroxisomes of plants. Several biochemical pathways have been modified in order to achieve this, including the isoprenoid pathway, the fatty acid biosynthetic pathway, and the fatty acid β-oxidation pathway. PHA synthesis has been demonstrated in a number of plants, including monocots and dicots, and up to 40% PHA per gram dry weight has been demonstrated in Arabidopsis thaliana. Despite some successes, production of PHA in crop plants remains a challenging project. PHA synthesis at high level in vegetative tissues, such as leaves, is associated with chlorosis and reduced growth. The challenge for the future is to succeed in synthesis of PHA copolymers with a narrow range of monomer compositions, at levels that do not compromise plant productivity. This goal will undoubtedly require a deeper understanding of plant biochemical pathways and how carbon fluxes through these pathways can be manipulated, areas where plant "omics" can bring very valuable contributions.

Fact Sheet: Terrorism, 2009

Learn about the nature of terrorism. • Terrorists often choose targets that offer little danger to themselves and areas with relatively easy public access. • Foreign terrorists look for visible targets where they can avoid detection before or after an attack such as international airports, large cities, major international events, resorts, and high-profile landmarks. Learn about the different types of terrorist weapons including explosives, kidnappings, hijackings, arson, and shootings. Prepare to deal with a terrorist incident by adapting many of the same techniques used to prepare for other crises.

Predatory cannibalism in Drosophila melanogaster larvae.

Hunting live prey is risky and thought to require specialized adaptations. Therefore, observations of predatory cannibalism in otherwise non-carnivorous animals raise questions about its function, adaptive significance and evolutionary potential. Here we document predatory cannibalism on larger conspecifics in Drosophila melanogaster larvae and address its evolutionary significance. We found that under crowded laboratory conditions younger larvae regularly attack and consume 'wandering-stage' conspecifics, forming aggregations mediated by chemical cues from the attacked victim. Nutrition gained this way can be significant: an exclusively cannibalistic diet was sufficient for normal development from eggs to fertile adults. Cannibalistic diet also induced plasticity of larval mouth parts. Finally, during 118 generations of experimental evolution, replicated populations maintained under larval malnutrition evolved enhanced propensity towards cannibalism. These results suggest that, at least under laboratory conditions, predation on conspecifics in Drosophila is a functional, adaptive behaviour, which can rapidly evolve in response to nutritional conditions.

Ethyl glucuronide in plant extracts :O16

Introduction: The specificity of ethyl glucuronide (EtG) in hair as marker of alcohol consumption exceeds by far those of fatty acid ethyl esters. False positive cases are therefore very rare but not excluded as recent publications have shown. Especially, the use of plant extracts containing high percentages of ethanol can lead to EtG hair concentrations typically found in cases of chronic alcohol consumption. As proposed by Baumgartner et al., a nucleohilic substitution could most likely explain this phenomenon. Fresh and dried plants as well as commercial hair lotions based on plants extracts have been analysed for EtG presence or EtG formation. Methods: Urtica dioica, Plantago lanceolata, Cortex Quercus, Sempervivum, Armoracia rusticana, Juniperus communis, Brassica alba, Thymian vulgaris, Salvia officinalis, Majorana hortensis, Aloe vera, birch gingko and green tea leafs, ginger, lemon grass were extracted in water, water/ethanol (50/50) and ethanol (100%). The extracts as well as diluted hair lotions were measured by immunological test (Microgenics DRI® EtG assay) and by LC-MS/MS on Shimadzu Nexera UHPLC coupled with an AB Sciex 4500 QTrap. Results: EtG could not be detected in water extracts of all tested plants. However, DRI® EtG assay indicated the presence of EtG in 66% of the tested ethanolic plant extracts. That could only be confirmed by mass spectrometry in the cases of fresh thyme as well as in dried birch, oak and plantain extracts where EtG concentrations between of 0.25 and 2,09 mg/l were measured. In one hair lotion, the EtG concentration was 0,76 mg/l. Conclusion: Ethanolic plant extracts represents a non-negligible risk for false positive EtG hair tests, especially when applied as lotion without following washing out. The use of hair care products must therefore be evaluated at every hair sampling. In case of doubt, the product should be analysed by mass spectrometric methods since the presence of EtG can't be proven by use of the DRI® EtG assay, only. Our results support Baumgartner's assumption of a nucleophilic substitution in presence of ethanol because EtG was only measured in the ethanolic extracts.

TRANSCRIPTION FACTORS INVOLVED IN PLANT DEFENCE AGAINST INSECT HERBIVORES IN ARABIDOPSIS THALIANA

Afin de pouvoir se défendre contre les insectes nuisibles, les plantes ont développé plusieurs stratégies leur permettant de maximiser leurs chances de survie et de reproduction. Parmi elles, les plantes sont souvent pourvues de barrières physiques telles que les poils urticants, les épines et la cuticule. En plus, les plantes sont capables de produire des protéines anti-digestives et des métabolites secondaires insecticides tels que la nicotine, les tannins ou les glucosinolates (GS). La mise en place de ces barrières physiques et chimiques comporte un coût énergétique au détriment de la croissance et de la reproduction. Par conséquent, en absence d'insectes, la plante investit la majeure partie de son énergie dans le développement et la croissance. A l'inverse, une blessure causée par un insecte provoquera une croissance ralentie, une augmentation de la densité de poils urticants ainsi que la synthèse de défenses chimiques. Au niveau moléculaire, cette défense inductible est régulée par l'hormone végétale acide jamsonique (AJ). En réponse à l'attaque d'un insecte, la plante produit cette hormone en grande quantité, ce qui se traduira par une forte expression de gènes de défense. Pendant ma thèse, j'ai essayé de découvrir quels étaient les facteurs de transcription (FT) responsables de l'expression des gènes de défense dans Arabidopsis thaliana. J'ai ainsi pu démontrer que des plantes mutées dans les FTs comme MYC2, MYC3, MYC4, ZAT10, ZAT12, AZF2, WRKY18, WRKY40, WRKY6, ANAC019, ANAC55, ERF13 et RRTF1 deviennent plus sensibles aux insects de l'espèce Spodoptera littoralis. Par la suite, j'ai également pu montrer que MYC2, MYC3 et MYC4 sont probablement la cible principale de la voie de signalisation du AJ et qu'ils sont nécessaires pour l'expression de la majorité des gènes de défense dont la plupart sont essentiels à la biosynthèse des GS. Une plante mutée simultanément dans ces trois protéines est par conséquent incapable de synthétiser des GS et devient hypersensible aux insectes. J'ai également pu démontrer que les GS sont uniquement efficaces contre les insectes généralistes tels S. littoralis et Heliothis virescens alors que les insectes spécialisés sur les Brassicaceae comme Pieris brassicae et Plutella xylostella se sont adaptés en développant des mécanismes de détoxification. - In response to herbivore insects, plants have evolved several defence strategies to maximize their survival and reproduction. For example, plants are often endowed with trichomes, spines and a thick cuticule. In addition, plants can produce anti-digestive proteins and toxic secondary metabolites like nicotine, tannins and glucosinolates (GS). These physical and chemical barriers have an energetic cost to the detriment of growth and reproduction. As a consequence, in absence of insects, plants allocate their energy to development and growth. On the contrary, an attack by herbivore insects will affect plant growth, increase trichome density and induce the production of anti-digestive proteins and secondary metabolites. At the molecular level, this inducible defence is regulated by the phytohormone jasmonic acid (JA). Thus, an attack by herbivores will be followed by a burst of JA that will induce the expression of defence genes. The aim of my thesis was to characterize which transcription factors (TF) regulate the expression of these defence genes in Arabidopsis thaliana. I could show that plants mutated in various TFs like MYC2, MYC3, MYC4, ZAT10, ZAT12, AZF2, WRKY18, WRKY40, WRKY6, ANAC019, ANAC55, ERF 13 and RRTFl were more susceptible to the herbivore Spodoptera littoralis. Furthermore, I could demonstrate that MYC2, MYC3 and MYC4 are probably the main target of the JA-signalling pathway and that they are necessary for the insect-mediated induction of most defence genes including genes involved in the biosynthesis of GS. A triple mutant myc2myc3myc4 is depleted of GS and consequently hypersensitive to insects. Moreover, I showed that GS are only efficient against generalist herbivores like S. littoralis and Heliothis virescens whereas specialized insects like Pieris brassicae and Plutella xylostella have evolved detoxification mechanisms against GS.

Vulnerabilities of fingerprint reader to fake fingerprints attacks

The purpose of this research is to assess the vulnerabilities of a high resolution fingerprint sensor when confronted with fake fingerprints. The study has not been focused on the decision outcome of the biometric device, but essentially on the scores obtained following the comparison between a query (genuine or fake) and a template using an AFIS system. To do this, fake fingerprints of 12 subjects have been produced with and without their cooperation. These fake fingerprints have been used alongside with real fingers. The study led to three major observations: First, genuine fingerprints produced scores higher than fake fingers (translating a closer proximity) and this tendency is observed considering each subject separately. Second, scores are however not sufficient as a single measure to differentiate these samples (fake from genuine) given the variation due to the donors themselves. That explains why fingerprint readers without vitality detection can be fooled. Third, production methods and subjects greatly influence the scores obtained for fake fingerprints.

Genesis and classification of Oxisols in a highland toposequence of the upper Jequitinhonha Valley (MG)

The Brazilian System of Soil Classification (SiBCS) is a taxonomic system, open and in permanent construction, as new knowledge on Brazilian soils is obtained. The objective of this study was to characterize the chemical, physical, morphological, micro-morphological and mineralogical properties of four pedons of Oxisols in a highland toposequence in the upper Jequitinhonha Valley, emphasizing aspects of their genesis, classification and landscape development. The pedons occupy the following slope positions: summit - Red Oxisol (LV), mid slope (upper third) - Yellow-Red Oxisol (LVA), lower slope (middle third)- Yellow Oxisol (LA) and bottom of the valley (lowest third) - "Gray Oxisol" ("LAC"). These pedons were described and sampled for characterization in chemical and physical routine analyses. The total Fe, Al and Mn contents were determined by sulfuric attack and the Fe, Al and Mn oxides in dithionite-citrate-bicarbonate and oxalate extraction. The mineralogy of silicate clays was identified by X ray diffraction and the Fe oxides were detected by differential X ray diffraction. Total Ti, Ga and Zr contents were determined by X ray fluorescence spectrometry. The "LAC" is gray-colored and contains significant fragments of structure units in the form of a dense paste, characteristic of a gleysoil, in the horizons A and BA. All pedons are very clayey, dystrophic and have low contents of available P and a pH of around 5. The soil color was related to the Fe oxide content, which decreased along the slope. The decrease of crystalline and low- crystalline Fe along the slope confirmed the loss of Fe from the "LAC". Total Si increased along the slope and total Al remained constant. The clay fraction in all pedons was dominated by kaolinite and gibbsite. Hematite and goethite were identified in LV, low-intensity hematite and goethite in LVA, goethite in LA. In the "LAC", no hematite peaks and goethite were detected by differential X ray diffraction. The micro-morphology indicated prevalence of granular microstructure and porosity with complex stacking patterns.. The soil properties in the toposequence converged to a single soil class, the Oxisols, derived from the same source material. The landscape evolution and genesis of Oxisols of the highlands in the upper Jequitinhonha Valley are related to the evolution of the drainage system and the activity of excavating fauna.

Spodosols pedogenesis under barreiras formation and sandbank environments in the south of Bahia

Morphologically differentiated Spodosols usually occur in the Coastal Plain of the South of Bahia and North of Espírito Santo. They are found in profiles known as "muçungas", i.e. sandy soils that accumulate water. In these areas, two kinds of Spodosols, different from those in the Restinga area, can be found: Spodosols with E albic horizon (white muçunungas) and without this horizon (black muçunungas). Eight soil profiles with spodic characteristics were collected and described in order to evaluate differences in the formation process of Barreiras and Restinga Spodosols in the South of Bahia. The soil profiles were also characterized chemically, physically and mineralogically. Additionally, texture and chemical analysis, Fe and Al extraction by sodium dithionite-citrate-bicarbonate (DBC), acid ammonium oxalate and sodium pyrophosphate, ammonium oxalate extract optic density (DOox), sulphuric acid attack, and X ray difractometry of the clay fraction were performed. In the Spodosols of the Barreiras area, fragipan was found the spodic layers. Cemented B spodic horizon were observed in the white muçunungas, and granular structure and dark color from the surface in the black muçunungas. There was no fragipan or hard spodic horizon in the Restinga Spodosol. This soil is acid, dystrophic and alic, with sandy texture and high clay percentages in the spodic horizons. The CEC, based on H + Al, is predominantly represented by the organic matter. The most representative components of the mineral phase of the clay fraction are kaolinite and possibly vermiculite traces with interlayered hydroxy. Chemical, physical, morphological and mineralogical differences were observed between the Barreiras and Restinga environments. The black and white muçunungas differ in morphologic and chemical properties only.

Study of the regulation of antifungal activity in plant-associated pseudomas fluorescens

RésuméEn agriculture d'énormes pertes sont causées par des champignons telluriques pathogènes tels que Thielaviopsis, Fusarium, Gaeumannomyces et Rhizoctonia ou encore l'oomycète Pythium. Certaines bactéries dites bénéfiques, comme Pseudomonas fluorescens, ont la capacité de protéger les plantes de ces pathogènes par la colonisation de leur racines, par la production de métabolites secondaires possédants des propriétés antifongiques et par l'induction des mécanismes de défenses de la plante colonisée. P. fluorescens CHAO, une bactérie biocontrôle isolée d'un champ de tabac à Payerne, a la faculté de produire un large spectre de métabolites antifongiques, en particulier le 2,4- diacétylphloroglucinol (DAPG), la pyolutéorine (PLT), le cyanure d'hydrogène (HCN), la pyrrolnitrine (PRN) ainsi que des chélateurs de fer.La plante, par sécrétion racinaire, produit des rhizodéposites, source de carbone et d'azote, qui profitent aux populations bactériennes vivant dans la rhizosphere. De plus, certains stresses biotiques et abiotiques modifient cette sécrétion racinaire, en terme quantitatif et qualitatif. De leur côté, les bactéries bénéfiques, améliorent, de façon direct et/ou indirect, la croissance de la plante hôte. De nombreux facteurs biotiques et abiotiques sont connus pour réguler la production de métabolites secondaires chez les bactéries. Des études récentes ont démontré l'importance de la communication entre la plante et les bactéries bénéfiques afin que s'établisse une interaction profitant à chacun des deux partis. Il est ainsi vraisemblable que les populations bactériennes associées aux racines soient capables d'intégrer ces signaux et d'adapter spécifiquement leur comportement en conséquence.La première partie de ce travail de thèse a été la mise au point d'outils basés sur la cytométrie permettant de mesurer l'activité antifongique de cellules bactériennes individuelles dans un environnent naturel, les racines des plantes. Nous avons démontré, grâce à un double marquage aux protéines autofluorescentes GFP et mCherry, que les niveaux d'expression des gènes impliqués dans la biosynthèse des substances antifongiques DAPG, PLT, PRN et HCN ne sont pas les mêmes dans des milieux de cultures liquides que sur les racines de céréales. Par exemple, l'expression de pltA (impliqué dans la biosynthèse du PLT) est quasiment abolie sur les racines de blé mais atteint un niveau relativement haut in vitro. De plus cette étude a mis en avant l'influence du génotype céréalien sur l'expression du gène phlA qui est impliqué dans la biosynthèse du DAPG.Une seconde étude a révélé la communication existant entre une céréale (orge) infectée par le pathogène tellurique Pythium ultimum et P. fluorescens CHAO. Un système de partage des racines nous a permis de séparer physiquement le pathogène et la bactérie bénéfique sur la plante. Cette méthode a donné la possibilité d'évaluer l'effet systémique, causé par l'attaque du pathogène, de la plante sur la bactérie biocontrôle. En effet, l'infection par le phytopathogène modifie la concentration de certains composés phénoliques dans les exsudats racinaires stimulant ainsi l'expression de phi A chez P.fluorescens CHAO.Une troisième partie de ce travail focalise sur l'effet des amibes qui sont des micro-prédateurs présents dans la rhizosphere. Leur présence diminue l'expression des gènes impliqués dans la biosynthèse du DAPG, PLT, PRN et HCN chez P.fluorescens CHAO, ceci en culture liquide et sur des racines d'orge. De plus, des molécules provenant du surnageant d'amibes, influencent l'expression des gènes requis pour la biosynthèse de ces antifongiques. Ces résultats illustrent que les amibes et les bactéries de la rhizosphere ont développé des stratégies pour se reconnaître et adapter leur comportement.La dernière section de ce travail est consacrée à l'acide indole-acétique (LA.A), une phytohormone connue pour son effet stimulateur sur phlA. Une étude moléculaire détaillée nous a démontré que cet effet de l'IAA est notamment modulé par une pompe à efflux (FusPl) et de son régulateur transcriptionnel (MarRl). De plus, les gènes fusPl et marRl sont régulés par d'autres composés phénoliques tels que le salicylate (un signal végétal) et l'acide fusarique (une phytotoxine du pathogène Fusarium).En résumé, ce travail de thèse illustre la complexité des interactions entre les eucaryotes et procaryotes de la rhizosphère. La reconnaissance mutuelle et l'instauration d'un dialogue moléculaire entre une plante hôte et ses bactéries bénéfiques associées? sont indispensables à la survie des deux protagonistes et semblent être hautement spécifiques.SummaryIn agriculture important crop losses result from the attack of soil-borne phytopathogenic fungi, including Thielaviopsis, Fusarium, Gaeumannomyces and Rhizoctonia, as well as from the oomycete Pythium. Certain beneficial microorganisms of the rhizosphere, in particular Pseudomonas fluorescens, have the ability to protect plants against phytopathogens by the intense colonisation of roots, by the production of antifungal exoproducts, and by induction of plant host defences. P. fluorescens strain CHAO, isolated from a tobacco field near Payerne, produces a large array of antifungal exoproducts, including 2,4-diacetylphloroglucinol (DAPG), pyoluteorin (PLT), hydrogen cyanide (HCN), pyrrolnitrin (PRN) and iron chelators. Plants produce rhizodeposites via root secretion and these represent a relevant source of carbon and nitrogen for rhizosphere microorganisms. Various biotic and abiotic stresses influence the quantity and the quality of released exudates. One the other hand, beneficial bacteria directly or indirectly promote plant growth. Biotic and abiotic factors regulate exoproduct production in biocontrol microorganisms. Recent studies have highlighted the importance of communication in establishing a fine-tuned mutualist interaction between plants and their associated beneficial bacteria. Bacteria may be able to integrate rhizosphere signals and adapt subsequently their behaviour.In a first part of the thesis, we developed a new method to monitor directly antifungal activity of individual bacterial cells in a natural environment, i.e. on roots of crop plants. We were able to demonstrate, via a dual-labelling system involving green and red fluorescent proteins (GFP, mCherry) and FACS-based flow cytometry, that expression levels of biosynthetic genes for the antifungal compounds DAPG, PLT, PRN, and HCN are highly different in liquid culture and on roots of cereals. For instance, expression of pltA (involved in PLT biosynthesis) was nearly abolished on wheat roots whereas it attained a relatively high level under in vitro conditions. In addition, we established the importance of the cereal genotype in the expression of phi A (involved in DAPG biosynthesis) in P. fluorescens CHAO.A second part of this work highlighted the systemic communication that exists between biocontrol pseudomonads and plants following attack by a root pathogen. A split-root system, allowing physical separation between the soil-borne oomycete pathogen Phytium ultimum and P. fluorescens CHAO on barley roots, was set up. Root infection by the pathogen triggered a modification of the concentration of certain phenolic root exudates in the healthy root part, resulting in an induction ofphlA expression in P. fluorescens CHAO.Amoebas are micro-predators of the rhizosphere that feed notably on bacteria. In the third part of the thesis, co-habitation of Acanthamoeba castellanii with P. fluorescens CHAO in culture media and on barley roots was found to significantly reduce bacterial expression of genes involved in the biosynthesis of DAPG, PLT, HCN and PRN. Interestingly, molecular cues present in supernatant of A. castelanii induced the expression of these antifungal genes. These findings illustrate the strategies of mutual recognition developed by amoeba and rhizosphere bacteria triggering responses that allow specific adaptations of their behaviour.The last section of the work focuses on indole-3-acetic acid (IAA), a phytohormone that stimulates the expression of phi A. A detailed molecular study revealed that the IAA-mediated effect on phi A is notably modulated by an efflux pump (FusPl) and its transcriptional regulator (MarRl). Remarkably, transcription of fusPl and marRl was strongly upregulated in presence of other phenolic compounds such as salicylate (a plant signal) and fusaric acid (a phytotoxin of the pathogenic fungus Fusarium).To sum up, this work illustrates the great complexity of interactions between eukaryotes and prokaryotes taking place in the rhizosphere niche. The mutual recognition and the establishment of a molecular cross-talk between the host plant and its associated beneficial bacteria are essential for the survival of the two partners and these interactions appear to be highly specific.

Vaccinia immune globulin: current policies, preparedness, and product safety and efficacy.

In 1980 the World Health Organization declared that smallpox was eradicated from the world, and routine smallpox vaccination was discontinued. Nevertheless, samples of the smallpox virus (variola virus) were retained for research purposes, not least because of fears that terrorist groups or rogue states might also have kept samples in order to develop a bioweapon. Variola virus represents an effective bioweapon because it is associated with high morbidity and mortality and is highly contagious. Since September 11, 2001, countries around the world have begun to develop policies and preparedness programs to deal with a bioterror attack, including stockpiling of smallpox vaccine. Smallpox vaccine itself may be associated with a number of serious adverse events, which can often be managed with vaccinia immune globulin (VIG). VIG may also be needed as prophylaxis in patients for whom pre-exposure smallpox vaccine is contraindicated (such as those with eczema or pregnant women), although it is currently not licensed in these cases. Two intravenous formulations of VIG (VIGIV Cangene and VIGIV Dynport) have been licensed by the FDA for the management of patients with progressive vaccinia, eczema vaccinatum, severe generalized vaccinia, and extensive body surface involvement or periocular implantation following inadvertent inoculation.

Temporal distribution and magnitude of the vulnerability period around stroke depend on stroke subtype.

Background: We aimed to analyze the rate and time distribution of pre- and post-morbid cerebrovascular events in a single ischemic stroke population, and whether these depend on the etiology of the index stroke. Methods: In 2,203 consecutive patients admitted to a single stroke center registry (ASTRAL), the ischemic stroke that led to admission was considered the index event. Frequency distribution and cumulative relative distribution graphs of the most recent and first recurrent event (ischemic stroke, transient ischemic attack, intracranial or subarachnoid hemorrhage) were drawn in weekly and daily intervals for all strokes and for all stroke types. Results: The frequency of events at identical time points before and after the index stroke was mostly reduced in the first week after (vs. before) stroke (1.0 vs. 4.2%, p < 0.001) and the first month (2.7 vs. 7.4%, p < 0.001), and then ebbed over the first year (8.4 vs. 13.1%, p < 0.001). On daily basis, the peak frequency was noticed at day -1 (1.6%) with a reduction to 0.7% on the index day and 0.17% 24 h after. The event rate in patients with atherosclerotic stroke was particularly high around the index event, but 1-year cumulative recurrence rate was similar in all stroke types. Conclusions: We confirm a short window of increased vulnerability in ischemic stroke and show a 4-, 3- and 2-fold reduction in post-stroke events at 1 week, 1 month and 1 year, respectively, compared to identical pre-stroke periods. This break in the 'stroke wave' is particularly striking after atherosclerotic and lacunar strokes.

Fact Sheet: Terrorism, 2011

Learn about the nature of terrorism. • Terrorists often choose targets that offer little danger to themselves and areas with relatively easy public access. • Foreign terrorists look for visible targets where they can avoid detection before or after an attack such as international airports, large cities, major international events, resorts, and high-profile landmarks. Learn about the different types of terrorist weapons including explosives, kidnappings, hijackings, arson, and shootings. Prepare to deal with a terrorist incident by adapting many of the same techniques used to prepare for other crises.