För att hålla vattendragen och miljön rena, renas avloppsvattnet för att nå ett visst mått innan det släpps ut. Vi gjorde en fallstudie för att utvärdera metoderna som används för att behandla avloppsvatten i tre steg: primär, sekundär och tertiär i delstaten Texas, USA. Vi fann att olika fysikaliska, kemiska och biologiska bearbetningsmetoder används i stor utsträckning i dessa tre stadier. Även om en del av det slam som produceras i en avloppsvattenreningsanläggning utsätts för anaerob rötning (AD) process för att producera biogas, skickas majoriteten av dem till deponier som är ohållbart eftersom det skapar miljöföroreningar som läckage av näringsämnen, påverkar markens biologiska mångfald och släpper ut giftiga gaser och växthusgaser (GHG) som CH4, CO2, N2O. Den mest hållbara och prisvärda metoden för att behandla avloppsvatten är att använda mikroalger och några av fördelarna inkluderar: (i) använda CO2 som en kolkälla och generera syre, (ii) synergistiskt arbeta med aeroba bakterier som bryter ner organiska föroreningar i vatten på kort tid tid, (iii) högeffektiv bindning av överskott av kväve, fosfor och tungmetaller i avloppsvatten. Flera algbaserade reningsmetoder för avloppsvatten har utvecklats. Bland dem är reaktorn Rotating Algal Biofilm (RAB) en av de ledande behandlingsmetoderna som använder ett roterande band som består av syntetiska material som rör sig på en cylinder som är delvis nedsänkt i avloppsvatten. Algbiomassan kunde skördas från bältet genom att helt enkelt skrapa materialets yta. Vi uppskattade att ~1793,7 miljoner liter avloppsvatten behandlas dagligen i delstaten Texas och hypotetiskt om allt avloppsvatten behandlas med RAB skulle ~174,2 ton algbiomassa kunna produceras. Denna algbiomassa kan användas för AD-processen eller vidarebearbetas och fraktioneras till lipider, kolhydrater och proteiner med hjälp av etablerade hydrotermiska bearbetningsmetoder och användas som byggstenar för att producera bränslen, kemikalier och biomaterial. Tre scenarier har undersökts som belyser potentialen och fördelarna med att använda alger för att behandla avloppsvatten jämfört med konventionella metoder för avloppsvattenrening och hur denna övergång kommer att gynna ekonomin och miljön. / To keep the waterways and environment clean, wastewater is treated to reach a certain metric before they are discharged.  We did a case study to evaluate the methods used to treat wastewater in three stages: primary, secondary, and tertiary in the state of Texas, United States. We found different physical, chemical, and biological processing methods are widely used in these three stages. Though some of the sludge produced in a wastewater treatment facility are subjected to anaerobic digestion (AD) process to produce biogas, the majority of them are sent to landfills which is unsustainable as it creates environmental pollution such as nutrient leaching, impacts soil biodiversity, and releases toxic gases and greenhouse gases (GHGs) such as CH4, CO2, N2O. The most sustainable and affordable method of treating wastewater is using microalgae and some of the advantages include: (i) use CO2 as a carbon source and generate oxygen, (ii) synergistically working with aerobic bacteria breaking down organic contaminants in water in a short period of time, (iii) highly efficient sequester of excess nitrogen, phosphorus, and heavy metals in wastewater. Several algal based wastewater treatment methods have been developed. Among them, the Rotating Algal Biofilm (RAB) reactor is one of the leading treatment methods that uses a rotating belt made up of synthetic materials moving on a cylinder partially submerged in wastewater. The algal biomass could be harvested from the belt by simply scrapping the material's surface. We estimated that ~1793.7 million gallons of wastewater are treated daily in the state of Texas and hypothetically if all the wastewater is treated using RAB ~174.2 tons of algal biomass could be produced. This algal biomass can be used for the AD process or further processed and fractionated to lipids, carbohydrates, and proteins using established hydrothermal processing methods and used as building blocks for producing fuels, chemicals, and biomaterials. Three scenarios have been investigated, highlighting the potential and benefits of using algae to treat wastewater compared to conventional wastewater treatment methods and how this transition will benefit the economy and environment.

Weltweit kommt es jährlich zu 90 Mio. Neuinfektionen mit dem sexuell übertragbaren Erreger Chlamydia trachomatis. Allerdings sind die Faktoren, die eine erfolgreiche bakterielle Vermehrung ermöglichen, weitgehend unbekannt. Während ihrer obligat intrazellulären Entwicklung sind Chlamydien auf die Errichtung und Erhaltung ihrer Nische, der Inklusion, angewiesen. Durch Interaktionen mit vesikulären Transportwegen der Wirtszelle, welche z.B. Sphingolipide transportieren, sichern die Bakterien ihr Überleben. In der vorliegenden Arbeit konnte gezeigt werden, dass Chlamydien während einer Infektion die Auflösung der Struktur des Golgi-Apparates induzieren. Mit Hilfe der RNA-Interferenz-Technik (RNAi) wurden die Auswirkungen des Verlustes von Golgi-Strukturproteinen auf die bakterielle Vermehrung untersucht. Der funktionelle Ausfall von Golginen, wie z.B. Golgin-84 führte zu einer Fragmentierung des Golgi-Apparates. Diese begünstigte die chlamydiale Produktion neuer infektiöser Partikel, was eine verbesserte Versorgung mit Nährstoffen nahelegt. Im vesikulären Transport von Nährstoffen übernehmen Rab-Proteine eine Schlüsselrolle. Interessanterweise konnte in dieser Arbeit gezeigt werden, dass der Verlust von Rab6 und Rab11 durch RNAi zu einer signifikanten Verringerung der Anzahl infektiöser Nachkommen führte. In diesen Zellen wurde der Golgi-Apparat nicht fragmentiert und der Transport von Sphingolipiden zu den Bakterien war stark vermindert. Untersuchungen nach simultaner Herunterregulation von Golgin-84 und Rab6 oder Rab11 demonstrierten abschließend, dass eine Kontrolle der Golgin-84-induzierten Golgi-Fragmentierung über Rab-Proteine möglich sein könnte. Die Ergebnisse dieser Arbeit offenbaren einen neuen Zusammenhang zwischen der Struktur des Golgi-Apparates und dessen Kontrolle über Rab-Proteine und ermöglichen einen tieferen Einblick in die Funktion des Golgi-Apparates während einer Chlamydien-Infektion. / Worldwide, approximately 90 mio. people are infected with the obligate intracellular bacterium Chlamydia trachomatis. However the factors involved in its successful infection and replication remain unknown. Chlamydia survive and replicate within a membrane bound niche inside host cells, termed the inclusion. To ensure survival, the chlamydial inclusion intercepts vesicular trafficking pathways of the host cell to acquire essential nutrients, such as sphingolipids. However, the exact mechanisms by which Chlamydia acquire these lipids have not been elucidated. The present work established that infection of host mammalian cells with C. trachomatis induced fragmentation of the Golgi-apparatus, but details of the mechanism to the bacterium’s pathogenesis are still required. Using RNA-Interference the role of specific Golgi-apparatus structural proteins in bacterial infectivity was investigated. Knockdown of Golgins in host cells resulted in a fragmented Golgi-apparatus and an associated increase in chlamydial replication, suggesting an enhanced acquisition of nutrients. Since Rab-proteins are known to co-ordinate the intracellular vesicular transport of nutrients, their importance in chlamydial infectivity was also investigated. Interestingly, knock down of Rab6 and Rab11 led to a significant reduction in infectious progeny. Surprisingly, upon knock down of Rab6 or Rab11 the Golgi-apparatus remained intact and sphingolipid transport into the inclusion was severely perturbed. Finally, analysis of cells simultaneously depleted of golgin-84 and Rab6 or Rab11 suggested a possible role of Rab-proteins in the control of golgin-84-induced Golgi fragmentation. These data demonstrate a yet unknown relationship between the structure of the Golgi-apparatus and its regulation and control by Rab-proteins. Furthermore, this work contributes to the existing knowledge regarding the function of the Golgi-apparatus during chlamydial infections.

A neurodegeneração é um processo onde ocorre morte celular progressiva. O tráfego neuronal anterógrado e retrógado, e entre os compartimentos é essencial para a viabilidade celular. As proteínas Rabs pertencem à família de pequenas GTPases, com funções de tráfego de vesículas e organelas, para realizarem sua função as proteínas Rab podem recrutar proteínas motoras como as KIF 1B e KIF 5, responsáveis pelo transporte anterógrado mitocondrial. A associação do distúrbio do tráfego intracelular com doenças neurodegenerativas tem sido tema de estudos recentes. Com isso o objetivo do presente trabalho é analisar a expressão das proteínas Rab, bem como estudar as proteínas motoras que podem contribuir para o esclarecimento sobre os distúrbios no tráfego intracelular que antecedem a formação de agregados proteicos envolvidos em neurodegeneração. Para tanto, utilizou-se o modelo de tratamento com rotenona para indução de agregados em Ratos Lewis idosos que foram expostos a rotenona durante 4 semanas, em seguida foram avaliados os níveis de expressão das proteínas Rab no hipocampo, substância negra e locus coeruleus, por western blotting. Foram analisados também os níveis de expressão das proteínas motoras KIF1B e KIF5 antes e durante a formação de agregados proteicos, em culturas de células, de ratos Lewis neonatos, do hipocampo, substância negra e locus coeruleus tratadas com rotenona por 24 horas ou 48 horas nas concentrações de 0,1nM, 0, 3nM e 0,5nM. Foi observado diminuição dos níveis de expressão das proteínas Rab 1 nas regiões do hipocampo e locus coeruleus. Houve aumento de expressão das Rab 4,5 e 6 no hipocampo, porém na substância negra a expressão da Rab 1 aumentou e da Rab 6 diminuiu. Já no locus coeruleus in vivo a Rab 6 aumentou, mas as Rab 1, 5 e 11 diminuíram sua expressão. Já a expressão da KIF 5 aumentou com o tratamento de 0,1nM de rotenona e diminuiu após 0,5nM do xenobiótico por 48 horas in vitro, na mesma região. Na substância negra aumentaram as KIFs 1B e 5 após o tratamento com 0,5nM por 48 horas in vitro, mas diminuíram as KIF 1B e 5 após o tratamento com 0,3nM por 24 horas e KIF 5 após o tratamento com 0,1nM por 48 horas. Esses resultados permitem concluir que a expressão de proteínas importantes para o tráfego mitocondrial e de vesículas encontram-se alteradas e fazem parte dos eventos intracelulares que antecedem a neurodegeneração / Neurodegeneration is a process that leads to progressive cell death. The anterograde and retrograde neuronal traffic as well as the traffic between compartments are essential for cell viability. The Rab proteins belong to the small GTPases family with function of vesicles and organelle trafficking. Rab proteins can recruit motor proteins such as KIF 1B and KIF 5 that are responsible for anterograde mitochondrial transport. The association of intracellular traffic disturb with neurodegenerative diseases have been theme of recent studies. Thereat the objective of this study is analyze the expression of Rab and motor proteins that can contribute for the understanding about the disturb of the intracellular traffic that precedes protein aggregation involved in neurodegeneration. For this purpose it was employed the model of rotenone treatment for induction of aggregation in aged Lewis rats that were exposed to rotenone during 4 weeks in order to evaluate Rabs expression. The levels of motor proteins KIF 1B and KIF 5 expression were evaluated before and during the formation of protein aggregates in hippocampus, substantia nigra and locus coeruleus cell cultures of neonates Lewis rats, exposed to rotenone for 24 hours or 48 hours in the concentrations of 0.1nM, 0.3nM or 0.5nM. It was observed decreased levels of Rab 1 expression in hippocampus and locus coeruleus. Rabs 4,5 and 6 were increased in the hippocampus, but in the substantia nigra the expression of Rab 1 increased and Rab 6 decreased. In the locus coeruleus the Rab 6 increased, but Rabs 1, 5 and 11 decreased. The expression of KIF 5 increased after 0.1nM of rotenone and decreased after the exposure to 0.5nM of for 48 hours in cultured cell from the locus coeruleus. In the substantia nigra the KIF1B and KIF 5 increased after treatment with 0.5nM for 48 hours in vitro, but these protein decreased after treatment with 0.3nM for 24 hours in vitro, and KIF 5 after treatment with 0.1nM for 48 hours. These results allow us conclude that the expression of important proteins for the mitochondrial and vesicles traffic are altered and participate of intracellular events that precede the neurodegeneration

No description available.

A neurodegeneração é um processo onde ocorre morte celular progressiva. O tráfego neuronal anterógrado e retrógado, e entre os compartimentos é essencial para a viabilidade celular. As proteínas Rabs pertencem à família de pequenas GTPases, com funções de tráfego de vesículas e organelas, para realizarem sua função as proteínas Rab podem recrutar proteínas motoras como as KIF 1B e KIF 5, responsáveis pelo transporte anterógrado mitocondrial. A associação do distúrbio do tráfego intracelular com doenças neurodegenerativas tem sido tema de estudos recentes. Com isso o objetivo do presente trabalho é analisar a expressão das proteínas Rab, bem como estudar as proteínas motoras que podem contribuir para o esclarecimento sobre os distúrbios no tráfego intracelular que antecedem a formação de agregados proteicos envolvidos em neurodegeneração. Para tanto, utilizou-se o modelo de tratamento com rotenona para indução de agregados em Ratos Lewis idosos que foram expostos a rotenona durante 4 semanas, em seguida foram avaliados os níveis de expressão das proteínas Rab no hipocampo, substância negra e locus coeruleus, por western blotting. Foram analisados também os níveis de expressão das proteínas motoras KIF1B e KIF5 antes e durante a formação de agregados proteicos, em culturas de células, de ratos Lewis neonatos, do hipocampo, substância negra e locus coeruleus tratadas com rotenona por 24 horas ou 48 horas nas concentrações de 0,1nM, 0, 3nM e 0,5nM. Foi observado diminuição dos níveis de expressão das proteínas Rab 1 nas regiões do hipocampo e locus coeruleus. Houve aumento de expressão das Rab 4,5 e 6 no hipocampo, porém na substância negra a expressão da Rab 1 aumentou e da Rab 6 diminuiu. Já no locus coeruleus in vivo a Rab 6 aumentou, mas as Rab 1, 5 e 11 diminuíram sua expressão. Já a expressão da KIF 5 aumentou com o tratamento de 0,1nM de rotenona e diminuiu após 0,5nM do xenobiótico por 48 horas in vitro, na mesma região. Na substância negra aumentaram as KIFs 1B e 5 após o tratamento com 0,5nM por 48 horas in vitro, mas diminuíram as KIF 1B e 5 após o tratamento com 0,3nM por 24 horas e KIF 5 após o tratamento com 0,1nM por 48 horas. Esses resultados permitem concluir que a expressão de proteínas importantes para o tráfego mitocondrial e de vesículas encontram-se alteradas e fazem parte dos eventos intracelulares que antecedem a neurodegeneração / Neurodegeneration is a process that leads to progressive cell death. The anterograde and retrograde neuronal traffic as well as the traffic between compartments are essential for cell viability. The Rab proteins belong to the small GTPases family with function of vesicles and organelle trafficking. Rab proteins can recruit motor proteins such as KIF 1B and KIF 5 that are responsible for anterograde mitochondrial transport. The association of intracellular traffic disturb with neurodegenerative diseases have been theme of recent studies. Thereat the objective of this study is analyze the expression of Rab and motor proteins that can contribute for the understanding about the disturb of the intracellular traffic that precedes protein aggregation involved in neurodegeneration. For this purpose it was employed the model of rotenone treatment for induction of aggregation in aged Lewis rats that were exposed to rotenone during 4 weeks in order to evaluate Rabs expression. The levels of motor proteins KIF 1B and KIF 5 expression were evaluated before and during the formation of protein aggregates in hippocampus, substantia nigra and locus coeruleus cell cultures of neonates Lewis rats, exposed to rotenone for 24 hours or 48 hours in the concentrations of 0.1nM, 0.3nM or 0.5nM. It was observed decreased levels of Rab 1 expression in hippocampus and locus coeruleus. Rabs 4,5 and 6 were increased in the hippocampus, but in the substantia nigra the expression of Rab 1 increased and Rab 6 decreased. In the locus coeruleus the Rab 6 increased, but Rabs 1, 5 and 11 decreased. The expression of KIF 5 increased after 0.1nM of rotenone and decreased after the exposure to 0.5nM of for 48 hours in cultured cell from the locus coeruleus. In the substantia nigra the KIF1B and KIF 5 increased after treatment with 0.5nM for 48 hours in vitro, but these protein decreased after treatment with 0.3nM for 24 hours in vitro, and KIF 5 after treatment with 0.1nM for 48 hours. These results allow us conclude that the expression of important proteins for the mitochondrial and vesicles traffic are altered and participate of intracellular events that precede the neurodegeneration

Les Tunneling nanotubes (TNT) sont des protrusions cellulaires à base d'actine qui médient la communication cellulaire en transférant des cargos cellulaires. Les différents types de communication intercellulaires sont de plus en plus considérés comme des cibles potentielles pour le traitement de différentes maladies, telles que les maladies infectieuses liées aux virus et bactéries, les cancers ou les maladies neurodégénératives. Des études récentes ont mis en évidence un mécanisme de propagation d'agrégats protéiques ressemblant à la propagation du prion dans diverses maladies neurodégénératives non infectieuses telles que la maladie d'Alzheimer (AD), la démence frontotemporelle (FTD), la maladie de Parkinson (PD) et la maladie de Huntington. Ces maladies se caractérisent par l'accumulation de protéines mal repliées dans le cerveau des patients. Ainsi, on peut envisager de nouvelles stratégies thérapeutiques pour bloquer la propagation des protéines anormales dans tout le cerveau. Il a été démontré que les TNT pourraient jouer un rôle essentiel dans la propagation des agrégats de prions au sein du système nerveux central (SNC) et périphérique. Par conséquent, l'étude du mécanisme de la formation de TNT pourrait fournir de nouvelles idées sur le mécanisme de propagation de la maladie et de nouvelles cibles thérapeutiques. L'objectif de ma thèse était d'étudier le rôle du transfert des agrégats de protéines par les TNT entre les cellules et d'étudier le mécanisme de formation des TNT. Dans notre laboratoire, nous avons déjà montré que les TNT permettent le transfert de prions entre les cellules. Dans la première partie de mon doctorat, j'ai confirmé que les transferts d'agrégats de prions entre les cellules de CAD neuronales se faisaient par les TNT à l'intérieur de vésicules endocytiques (Zhu et al., 2015). De plus, en collaboration avec un collègue, nous avons fourni des preuves que les agrégats de prions pourraient être transférés entre des astrocytes primaires et des neurones et que ce transfert était médié par un contact cellulaire (Victoria et al., 2016). J'ai également collaboré à une autre étude où nous avons montré que les agrégats d'α-synucléine (caractéristiques de la maladie de Parkinson) peuvent être transférés entre les cellules à l'intérieur des lysosomes, et que ce transfert intercellulaire est médié par les TNT (Abounit et al., 2016). Dans mon deuxième projet, afin d'étudier le mécanisme de la formation de TNT, j'ai effectué un crible à haut débit pour les Rab GTPase. J'ai trouvé que Rab8 et Rab11 peuvent favoriser la formation des TNT, et que les cascades Rab8-VAMP3, Rab11-ERM et Rab8-Rab11 sont impliquées dans la formation des TNT. Mes données suggèrent que la polymérisation de l'actine et le trafic de membranes sont impliqués dans la formation des TNT. Ces résultats permettent d'éclairer le mécanisme de la formation des TNT et de fournir des preuves moléculaires que les Rab GTPases régulent ce processus. / Tunneling nanotubes are actin-based cell protrusions that mediate cell-to-cell communication by transferring cellular cargos. The different types of intercellular communication are increasing by being considered as potential targets for the treatment of various diseases, such as infectious diseases linked to viruses and bacteria, cancers or neurodegenerative diseases. Recent studies have highlighted a prion-like mechanism of propagation of protein misfolding in a variety of common, non-infectious, neurodegenerative diseases such as Alzheimer’s disease (AD), Frontotemporal dementia (FTD), Parkinson’s disease (PD), and Polyglutamine (PolyQ) diseases, which are characterized by the accumulation of misfolded proteins in the brain of patients. Thus, new therapeutic strategies to block propagation of protein misfolding throughout the brain can be envisaged. It has been shown that TNTs might play a critical role in spreading of prion aggregates within the CNS and from the periphery. Therefore, the study of mechanism of TNT formation could provide new insights on the mechanism of disease propagation and novel therapeutic targets. The aim of my thesis was to study the role of TNT-mediate protein aggregates transfer between cells and to investigate the mechanism of TNT formation. In our lab, we already reported TNT mediate prion transfer between cells. In the first part of my PhD, I further confirmed that prion aggregates transfer between neuronal CAD cells through TNT inside endocytic vesicles (Zhu et al., 2015). Furthermore in collaboration with a colleague, we provided evidences that prion aggregates could transfer between primary astrocytes and neurons and the transfer was mediated by cell-to-cell contact (Victoria et al., 2016). I also collaborated to another study where we showed that α-synuclein aggregates (Parkinson’s disease) can transfer between cells inside lysosomes, and the intercellular transfer is mediated by TNTs (Abounit et al., 2016).In my second project, in order to investigate the mechanism of TNT formation, I performed a High-content screening of Rab GTPase. I found that Rab8 and Rab11 can promote TNT formation, that Rab8-VAMP3, Rab11-ERM and Rab8-Rab11 cascades are involved in TNT formation. My data suggests that both actin polymerization and membrane trafficking are involved in TNT formation. These results help to shed light on the mechanism of TNT formation, and provide molecular evidences that Rab GTPases regulate this process.

Rab GTPases are major regulatory proteins of vesicle traffic and thus responsible for membrane identity, vesicle targeting and vesicle fusion. The angiosperm Rab GTPase family is grouped into eight clades (Rab-A to Rab-H) that are broadly conserved in animals and yeasts. It has been proposed that the Rab-A clade has diversified in land plants giving rise to six plant- specific structural subclasses, Rab-A1 to Rab-A6. Previous work suggests that the Arabidopsis Rab-A2 and Rab-A3 proteins define a novel endosomal compartment that lies on a pathway between the Golgi and the plasma membrane. In dividing cells, the Rab-A2/A3 compartment is implicated in biosynthetic traffic to the cell plate but it is unclear what traffics through this compartment in non-dividing cells. In this project, I investigated a range of membrane trafficking pathways in Arabidopsis thaliana. These were probed for dependency on RAB-A2a function, using the dominant negative approach combined with fluorescent marker technology. The data presented in this thesis suggests that RAB-A2a acts on a protein recycling pathway that is used by PIN2:GFP.

Obligate intracellular pathogens must acquire host cell-derived nutrients to facilitate their survival. One such bacterial pathogen, Anaplasma phagocytophilum, replicates within neutrophils and non-phagocytic cells in a bacterial-modified, host cell-derived vacuole. The bacterium exploits host cell vesicular trafficking pathways to route nutrients to its vacuole and utilizes Rab GTPases, guanine nucleotide-dependent, vesicular trafficking regulators, to do so. We previously discovered that the A. phagocytophilum vacuolar membrane is decorated with a specific subset of Rab GTPases - Rab1, Rab4A, Rab10, Rab11, Rab14, Rab22A and Rab35. Rab1 is exclusively found on the endoplasmic reticulum (ER) and thus its localization suggests that the bacterium intercepts the ER. Rab10, which is found on the ER, trans-Golgi and recycling endosomes, localizes to the vacuolar membrane in a guanine nucleotide-independent and bacterial protein synthesis-dependent manner. This suggests that a bacterial-encoded protein is binding to and recruiting Rab10. In this study, we determined that A. phagocytophilum hijacks two very nutrient-rich sources in the secretory pathway - trans-Golgi- and endoplasmic reticulum-derived vesicles. A. phagocytophilum localizes perinuclearly adjacent to the Golgi apparatus during infection. A. phagocytophilum and Anaplasma marginale, an intravacuolar bovine pathogen, also localize near the smooth ER and rough ER in both mammalian and tick host cells. These results are supported by transmission electron microscopy analyses of infected cells. Membrane markers for the rough ER label the peripheries of A. marginale and A. phagocytophilum organisms in both mammalian and tick host cells, which suggests that they are translocated into the pathogen vacuole. Furthermore, membrane markers for trans-Golgi-derived vesicles, including endogenous Rab10, label the periphery of intravacuolar A. phagocytophilum organisms. Markers for the trans-Golgi and the ER co-fractionate with A. phagocytophilum in density gradient centrifugation studies. siRNA knockdown of Rab10 pronouncedly reduces delivery of trans-Golgi markers into the pathogen-occupied vacuole, significantly reduces infection, and impedes bacterial conversion to the bacterium’s dense-cored form. These results suggest that trans-Golgi recruitment is Rab10 dependent and is critical for bacterial development. We identified an outer membrane A. phagocytophilum moonlighting protein, uridine monophosphate kinase that specifically binds GST-Rab10 in affinity chromatography assays and interacts with Rab10 in vivo. We hypothesize that this surface protein is mediating the interaction of the bacteria with intravacuolar trans-Golgi derived vesicles. This interaction could be critical for the delivery of essential nutrients. Taken together, these data suggest that nutritional virulence mechanisms of A. phagocytophilum and A. marginale target the host secretory pathway. Additionally, they suggest a novel mechanism whereby pathogens translocate nutrient rich vesicles into the pathogen vacuole, thus delivering essential nutrients right to their front door.

Le retard mental (RM) est une maladie incurable qui affecte 2 à 3 % de la population. Des mutations dans le gène GDI1, codant pour GDIa, un régulateur des GTPases Rab, sont associées à un RM chez l'homme. Un médicament ayant pour cible un gène ayant une fonction antagoniste à GDI1 pourrait réduire les symptômes de la maladie. Une mutation suppressive est une 2e mutation à un site différent de la mutation à l'étude, qui supprime le phénotype de la première mutation. Afin d'identifier ces suppresseurs génétiques, nous utilisons une approche couplant la génomique intégrative et la génétique chez un animal modèle, le nématode Caenorhabditis elegans. La réduction de l'expression de gdi-1 par traitement des nématodes à l'ARN interférent (ARNi) nous a permis d'observer 7 phénotypes: la stérilité (Ste); une altération de la morphologie de la gonade (Gon); une accumulation d'oocytes endomitotiques (Emo); une diminution de la contraction des cellules myoépithéliales de la gaine de la gonade, un défaut de morphologie des oocytes matures et une inhibition de l'endocytose des particules yolk (YPl70-GFP) par les oocytes. Nous montrons que gdi-1 joue un rôle important dans le contrôle de la morphologie des gonades et des oocytes. Notre laboratoire a récemment développé un outil bioinformatique permettant la prédiction d'interactions génétiques chez C. elegans. Nous avons utilisé les prédictions faites pour gdi-1 afin d'estimer la performance de ce prédicteur. Cette étude nous a permis d'identifier des partenaires fonctionnels de gdi-1 dont les fonctions neurologiques ont déjà été reconnues chez l'homme et de prouver le grand potentiel prédictif de notre outil bioinformatique. Parmi les partenaires fonctionnels identifiés pour gdi-1, il y a dyb-1 (dystrobrevin) qui est l'orthologue le plus près de dystrobrévine chez l'homme, une protéine associée à certaines formes de RM et une dystrophie musculaire. De plus, gdi-1 (ARNi) diminue le phénotype de dystrophie musculaire associé à dyb-1. Plusieurs gènes qui interagissent avec gdi-1, interagissent aussi avec des protéines motrices, dont la myosine qui contrôle la contraction de la machinerie actinemyosine. Ces résultats sont en accord avec le rôle montré pour gdi-1 dans le contrôle de la contraction de la gonade, ainsi que dans la morphologie des gonades et des oocytes. Notre approche nous a permis d'identifier des suppresseurs génétiques de gdi-1 chez le nématode C. elegans qui pourrait s'avérer être des cibles thérapeutiques prometteuses contre certaines formes de RM. De plus, cette approche nous a permis d'identifier une famille d'agents actifs pouvant être testée comme agents thérapeutiques contre les déficits neurologiques associés à la délétion fonctionnelle de GDI-1 chez la souris. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : gdi-1, retard mental, plasticité synaptique, dystrophie musculaire, ML-7, Rab, dystrobrévine, Caenorhabditis elegans, cible thérapeutique.

No description available.