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1
Rossanigo, Carlos Esteban. "Rôle de l'eau et de la température sur les taux de développement des nématodes parasites du tractus digestif des ruminants." Montpellier 2, 1992. http://www.theses.fr/1992MON20293.
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Les conditions climatiques ont un role preponderant sur la repartition geographique et temporelle des differentes especes de nematodes parasites des ruminants. Sur un exemple tire du parasitisme des bovins du centre-ouest d'argentine, temperature et pluviometrie contribuent a expliquer les niveaux d'infestation par les principaux genres. Un travail plus experimental est developpe en vue d'estimer le role de l'eau a proximite immediate des ufs et jeunes larves des nematodes (dans les feces), avec ou sans celui de la temperature, sur la partie du cycle de developpement allant de l'uf a la larve infestante. Par des depots de feces d'animaux parasites dans des situations climatiques diversifiees, il est montre que la temperature au sein des bouses etait le premier facteur conditionnant le taux de developpement des especes parasitant les bovins et que c'etait l'humidite ponderale des feces dans le cas des parasites d'ovin. Les exigences thermique et surtout hydriques sont definies au laboratoire pour huit especes parasites de bovins, ovins et cervides multipliees sur ovin. L'adaptation aux faibles humidites etait le principal caractere specifique. La taille des larves infestantes s'est averee dependre des conditions de developpement. Par des tests de laboratoire, il est montre que les petites larves developpees a des humidites faibles migraient et se degainaient plus lentement que les normales et semblaient avoir plus de mal a s'etablir chez l'hote. L'adaptation genetique aux conditions seches d'une lignee a ete tentee par une selection pendant 5 generations mais n'a pas revele d'evolution du taux de developpement dans ces conditions
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Walsh, Ellie Kathleen. "Investigating Root-Knot and Soybean Cyst Nematode Parasitic Interactions through Transcriptomic Analyses of the Host and Parasite." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471856126.
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Besnard-Cochennec, Nathalie. "Bonamia ostreae, parasite de l'huître plate, Ostrea edulis : sa position taxonomique parmi les parasites du groupe "microcell" : analyses des interactions hôte-parasite chez plusieurs populations d'huître plates." La Rochelle, 2001. http://www.theses.fr/2001LAROS073.
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La Bonamiose, maladie due au protozaire Bonamia ostreae a été détectée en 1979 pour la première fois en Bretagne au cours d'épisodes de mortalité. Depuis, cette maladie s'est propagée à tous les centres ostréicoles français, puis européens. Une autre espèce, B. Sp. A été décrite en Nouvelle Zélande et en Australie. En outre, deux autres parasites ont été rapprochés du genre Bonamia. Il s'agit de Mikrocytos mackini qui affecte les huîtres creuses, Crassostrea gigas au Canada et M. Roughleyi qui affecte les huîtres sauvages en Australie, Saccostrea commercialis. Ces quatre parasites sont regroupés sous le nom " microcell ". Les caractérisations ultrastructurales et moléculaires de ces parasites ont été réalisées. Elles ont permis d'inclure les parasites B. Ostreae, B. Sp et M. Roughleyi dans le phylum des Haplosporidia. Une nouvelle espèce a été créée pour B. Sp. , B. Exitiosus. Des outils moléculaires de détection des genres B. Spp. Et M. Spp et d'identification d'espèces ont été mis au point (PCR, PCR-RFLP, Hybridation in situ). L'analyse en cytométrie en flux nous a permis de caractériser morphologiquement et fonctionnellement les effecteurs cellulaires des mécanismes de défense des huîtres plates, les hémocytes circulants. Trois types hémocytaires ont été décrits sur la base de leur taille et de leur granularité. La répartition hémocytaire indique que la population des cellules agranuleuses est majoritaire dans l'hémolymphe. Quatre lectines hétérologues ont permis de discriminer les populations granuleuses et agranuleuses. La mise au point de dosage d'activités cellulaires a permis d'évaluer pour chaque type cellulaire l'expression de six activités déterminantes dans les mécanismes post-phagocytaires. Ces activités sont majoritaires dans les granulocytes. Les grandes cellules agranuleuses et les petits hyalinocytes présentent les mêmes activités mais les taux d'expression sont plus faibles. Les résultats de phagocytose, in vitro, suggèrent que le parasite B. Ostreae intervient de manière active dans la phagocytose. Les résidus glycosylés présents sur la membrane cytoplasmique du parasite sont identiques à ceux présents à la surface des granulocytes suggérant un rôle important des lectines dans les phénomènes de reconnaissance et d'internalisation. Afin de rechercher d'éventuelles relations entre ces paramètres et la résistance à la Bonamiose, différentes populations d'huîtres sensibles et sélectionnées ont été comparées. L'étude a permis de mettre en évidence une corrélation entre l'expression des estérases des grandes cellules agranuleuses et la résistance à la Bonamiose. Ces paramètres pourront servir de critère de sélection dans les programmes d'amélioration génétique.
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Kubát, Pavel. "Analogové elektronické emulátory obvodů neceločíselného řádu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-442475.
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Diploma thesis deals with circuits contain fractional-order elements. The first part of this paper deals with this problem, there were also described methods of design fractionalorder elements and types of circuits containing the fractiona-order elements which can be applied in practice. Used active elements for practical part can be found in the second chapter. Design of GIC circuits and implementation of fractional-order element inside the circuit are shown in the last chapture. Parasitic analysis and stability of frequency filter containing fractional-order element had been also described.
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Gomes, Jancarlo Ferreira 1960. "Processamento de amostras fecais e desenvolvimento da tecnica de analises de imagens por computador, para o diagnostico das enteroparasitoses." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317787.
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Orientador: Alexandre Xavier FalcãoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: No presente trabalho, averiguamos sobre processamentos de amostra fecal, desenvolvimento e avaliação de um sistema de computador para análise de imagem parasitária. Observamos que a etapa de processamento de fezes consistiu a etapa crítica, mas, essencial para o fornecimento de estruturas parasitárias limpas, com reduzida quantidade de microimpurezas fecais, ao sistema de análise por computador. Algumas técnicas parasitológicas convencionais, utilizando ou não kits comerciais, foram estudadas, e a de TF-Test (Three Fecal Test) apresentou menor teor de microimpurezas no final de processamento fecal. Todavia, este teor de microimpurezas era ainda muito grande, sendo ainda inadequado para análise computacional. Modificações foram introduzidas à técnica de TF-Test, com coloração dos componentes do sedimento fecal, utilizando um corante desenvolvido à base de Lugol, e seguido por degradação alcalina de microimpurezas, com uma solução clarificadora, previamente padronizada. Assim, a técnica de TF-Test Modificada contribuiu para o fornecimento de parasitos com poucas microimpurezas. O desenho do protótipo do sistema computacional para a análise de imagens incorporou: a técnica de TFTest Modificada; um microscópio óptico adaptado a uma bomba sucção peristáltica para conduzir uma alíquota de suspensão fecal processada à uma lâmina ou câmara tubular, onde estruturas parasitárias ou não apareciam em imagem; uma câmera digital; um monitor de vídeo para regulagem e captura de imagens; e um computador. Um banco de imagens foi construído, após coletas de amostras fecais foram efetuadas previamente em 4 regiões diferentes (Campinas, Botucatu, Avaré e Piraju) do estado de São Paulo, onde as enteroparasitoses são prevalentes. Os procedimentos de biossegurança e controle de qualidade contribuíram para que a perda da amostra fecal fosse pequena, não ultrapassando de 8%. Foi obtido um total de 16 espécies parasitárias, constituídos de helmintos e protozoários, e estes proveram uma coleção de 1.126 imagens ao computador. Ademais, o banco de imagens foi formado por informações adquiridas de 5.626 componentes parasitários e não parasitários, assim como, de dados sobre suas características de forma, textura e cor. A análise computacional baseou-se em um sistema de pipeline de técnicas de processamento de imagens, incluindo o uso de uma técnica denominada de Image-Foresting Transform (IFT). O pipeline consistiu em técnicas de segmentação de imagens para separar estruturas parasitárias e impurezas do fundo das imagens; em técnicas de extração para codificar características da forma, da cor e da textura dos parasitos; e em técnicas de reconhecimento e delineamento de imagens, visando distinguir parasitos de microimpurezas, de acordo com suas características próprias. A técnica de análise de imagens por computador (CIA) foi avaliada em comparação com a técnica de TF-Test Modificada de microscopia óptica, demonstrando alta sensibilidade de 95,3%, especificidade de 96,4%, e eficiência de 96,2 %. O conceito de concordância observada entre as duas técnicas estudadas foi de Quase Perfeito, em virtude do índice kapa (k) ter sido elevado, de 0,88. Esta técnica demonstrou ser altamente reprodutível, quando se ensaiaram em 10 diferentes ocasiões. Os achados deste trabalho apresentam perspectivas para industrialização do protótipo aqui desenvolvido, causando impacto na área de Saúde Pública, pois, no exame de fezes para população, há uma forte demanda de um sistema de automatização para detecção de enteroparasitos
Abstract: In the present study, we investigated on fecal sample processings, development and evaluation of a computer system for parasite image analysis. We observed that the fecal processing step was critical, but, essential for providing clean parasite structures, with reduced amount of fecal microdebris, to the system of computer analysis. Several conventional parasitologic techniques, using or not commercial kit, were studied, and TF-Test (Three Fecal Test) showed lower rate of microdebris at the end of fecal processing. However, this microdebris rate was still great, being unsuitable for computer analysis. The TF-Test technique was modified by staining the fecal sediment components, with a Lugol-based stain, followed by an alkaline degradation of fecal microdebris, using a clarifyer solution. So, the modified TF-Test technique became capable to supply parasite structure with little fecal microdebris. The prototype design of the computer system for the image analysis incorporated: the modified TF-Test technique; a optical microscope coupled to a peristaltic suction pump for leading an aliquot of processed fecal suspension to the tubular slide or chamber, where the parasite structures or microdebris appeared in tridimensional images; a digital camera; a video monitor to calibrate and capture images; and a computer. An image database was formed, after collecting fecal samples from prevalent regions (Campinas, Botucatu, Avaré and Piraju) of the State of São Paulo for enteroparasitosis. The total fecal sample loss was low, being less than 8%, since biosecurity and laboratory quality control protocols were frequently checked. A total of 16 parasite species were identified, consisting of helminths and protozoans, which provided a collection of 1.126 parasite images to the computer. Moreover, the image database was formed by information acquired from 5.626 parasite and nonparasite components, in addition to data on their shape characteristics, texture and color. The computational analysis was based on a pipeline of image processing techniques, including the use of a technique known as Image-Foresting Transform (IFT). The pipeline consisted of: a technique for image segmentation, in order to separate parasites and microdebris from background image; a technique for feature extraction to encode shape, color and texture characteristics of parasites; and techniques for pattern recognition and delineation, permitting to distinguish parasites from microdebris, according to their own features. The technique of computer image analysis (CIA) was evaluated in comparison with the optical microscope technique, named modified TF-Test, demonstrating a high sensitivity of 95,3%, specificity of 96,4% and efficiency of 96.2%. The agreement between two techniques was ranked as Almost Perfect, since the kappa (k) index has been high as much as 0.88. This technique proved to be reproducible, in a study, in which the assay was repeated 10 times, in different occasions. Our findings present good perspectives for the industrial production of the here developed prototype, causing impact on the Public Health area, since, in the fecal examination of the population, there is a strong demand for an automated system of enteroparasite detections
Doutorado
Doutor em Parasitologia
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Coustau, Christine. "Analyse génétique et physiologique des interactions hôte-parasite : le système Prosorhynchus squamatus-Mytilus." Montpellier 2, 1991. http://www.theses.fr/1991MON20029.
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Plusieurs niveaux d'interaction entre le trematode p. Squamatus et son premier hote intermediaire mytilus (mollusque, bivalve) sont analyses. L'hybridation entre m. Edulis et m. Galloprovincialis est caracterisee lors de l'etude de la structure genetique de populations naturelles de moules des cotes atlantiques francaises. Les individus du complexe m. Edulis/galloprovincialis presentent une susceptibilite differentielle a l'infestation par p. Squamatus, liee a leurs composants genomiques. Ce trematode induit une castration totale du mollusque par des voies biochimiques. Des experimentations in vitro montrent qu'il provoque d'une part, un blocage des mitoses goniales, et d'autre part une stimulation de la mobilisation des substances de reserve
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Cortesero, Anne-Marie. "La Recherche de l'hote chez eupelmus vuilleti (CRW) : analyse des relations tritrophiques entre la plante (Vigna unguiculata walp), l'hote (Bruchidius atrolineatus pic) et le parasitoïde." Tours, 1994. http://www.theses.fr/1994TOUR4008.
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Au cours de ce travail, nous avons analysé, au moyen de techniques olfactométriques, l'influence de divers stimuli olfactifs issus de la plante, vigna unguiculata et de l'hote, Bruchidius atrolineatus sur le comportement de recherche de l'hote par les femelles du parasitoide eupelmus vuilleti. Seules les odeurs émanant de graines et de gousses sèches de V. Unguiculata influencent le comportement locomoteur du paraitoïde. Les odeurs de plantes au stade végétatif ou celles de gousses vertes n'ont aucun effet. Les odeurs de larves, de nymphes et de fèces larvaires de B. Atrolineatus exercent un net effet attractif sur les femelles mais ne stimulent pas leur activité locomotrice. L'odeur de femelles de B. Atrolineatus n'influence que l'activité locomotrice du parasitoïde. L'analyse de la réponse du parasitoïde aux odeurs de plusieurs espèces de plantes et d'hotes montre que les femelles présentent une sensibilité spécifique et ne réagissent qu'aux odeurs émanant du complexe végétal/hote dont elles sont issues. Cette sensibilité spécifique résulte d'un processus d'apprentissage qui intervient juste après la mue imaginale lorsque la femelle se trouve encore à l'intérieur de la graine. Il existe également, chez E. Vuilleti, un apprentissage plus tardif, qui a lieu au moment de la ponte. Une expérience de ponte sur un complexe végétal/hote donné permet aux femelles d'apprendre les odeurs de ce complexe et ce, même s'il diffère de celui dont elles sont issues. Les mécanismes qui président à la rencontre avec l'hote une fois que la femelle parasitoïde adulte se trouve à proximité du microhabitat de l'hote ont également été analysés au cours de ce travail. La significaiton adaptative de ces résultats et leur intérêts en fonction des conditions rencontrées par les parasitoïdees dans les greniers et dans les cultures sont analysées.
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Raine, John Dale. "Proteomic analysis of the malarial parasite." Thesis, Imperial College London, 2005. http://hdl.handle.net/10044/1/11358.
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Brooker, Adam Jonathan. "Aspects of the biology and behaviour of Lernaeocera branchialis (Linnaeus, 1767) (Copepoda: Pennellidae)." Thesis, University of Stirling, 2007. http://hdl.handle.net/1893/343.
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Lernaeocera branchialis (L., 1767) is a parasitic copepod that parasitises a range of gadoids by anchoring in the proximity of the branchial chamber of its host, deriving nutrition from the blood of its host and causing serious pathogenic effects. This study investigates the taxonomy of the juvenile free-swimming stages and host location behaviour in the pre-metamorphosed adult female. The large size and distinctive appearance of the metamorphosed adult female stage, coupled with the wide exploitation and commercial importance of one of its principle final gadoid hosts, the cod (Gadus morhua L.), means that this species has long been recognised in the scientific literature, and here the extensive literature concerning this potentially important and damaging pathogen is re-examined to provide an up to date overview, which includes both aquaculture and wild fisheries perspectives. Due to disagreements between several descriptions of the L. branchialis juvenile stages, and because the majority of the descriptions are over 60 years old, the juvenile free-swimming stages are re-described, using current terminology and a combination of both light and confocal microscopy. The time of hatching and moults in these stages is also examined. Techniques for the automated creation of taxonomic drawings from confocal images using computer software are investigated and the possibilities and implications of this technique are discussed. The method of host location in L. branchialis is unknown but is likely to involve a variety of mechanisms, possibly including chemo-reception, mechano-reception and the use of physical phenomena in the water column, such as haloclines and thermoclines, to search for fish hosts. In this study the role of host-associated chemical cues in host location by adult female L. branchialis is investigated by analysing the parasites behavioural responses to a range of host-derived cues, in both a choice chamber and a 3D tracking arena. To analyse the data from the experiments, specialised computer software (“Paratrack”) was developed to digitise the paths of the parasites’ movements, and calculate a variety of behavioural parameters, allowing behaviour patterns to be identified and compared. The results show that L. branchialis responds to host-associated chemical cues in a similar way to many copepods in the presence of chemical cues. Of the different cues tested, gadoid conditioned water appears to be most attractive to the parasites, although the wide variation in behavioural responses may indicate that other mechanisms are also required for host location. The different behavioural responses of parasites to whiting (Merlangius merlangus L.) and cod (Gadus morhua) conditioned water, which are both definitive hosts, provide some evidence for sub-speciation in L. branchialis. The role of chemical cues in host location of L. branchialis, and the relative importance of chemical and physical cues in host location are discussed. As well as demonstrating several techniques, which show potential for further development, this work has improved our knowledge of the biology and life-cycle of L. branchialis. Further study of this, and other areas of L. branchialis biology and its host-parasite interactions, should assist the development of contingency plans for the effective management and control of this widespread and potentially devastating pathogen.
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Anderson, Barry Clayton. "The Response of Mice to Infection by the Parasitic Nematode Trichinella: A Comparison of Trichinella Spiralis and Trichinella Pseudospiralis." PDXScholar, 2002. https://pdxscholar.library.pdx.edu/open_access_etds/1658.
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The intracellular parasite Trichinella is a genus in phylum Nematoda that contains six named species including Trichinella spiralis and Trichinella pseudospiralis. These parasites infect a large variety of wild and domestic animals, human beings and a few species of birds. The parasitic strategies and the pathological effects on the host between trichinella spiralis and Trichinella pseudospiralis are quite different.
The purpose of this study is to gain an understanding of the physiological, immunological and pathological differences between these two species of Trichinella using infections in the mouse as a model. In the course of this research I have attempted to answer the following questions: A) Is cortisol a factor in the differences of the host response to Trichinella spiralis or Trichinella pseudospiralis? B) Are there differences in leukocyte response in the peripheral blood of Trichinella infected mice? C) Are there differences in the up-regulation or down-regulation of cell surface molecules on leukocytes in the spleens of Trichinella infected mice? D) Is there a difference in the degree of muscle damage (as measured by creatine phosphokinase) when infections by the two species of Trichinella are compared? E) Are there differences in angiogenesis and collagen deposition in Trichinella infected mice and are these differences related to cortisol? F) Is nitric oxide a component in parasite killing and are there differences in nitric oxide production in host mice when the two species of Trichinella are compared?
My research has shown that there are significant differences in the parasitic strategies and pathological consequences in mice infected with one or the other of the two species of Trichinella. The two species appear to generate different immune and inflammatory responses from the host. Trichinella pseudospiralis is much less damaging to the host, generates a very different peripheral blood response, stimulates the production of substantially greater levels of serum cortisol, generates a significantly different profile in cytokine production presents a very different cell surface antigen profile and does not produce a collagen nurse cell or generate an angiogenic response when compared to T spiralis. In addition, I have shown a role for nitric oxide in parasite killing and a role for serum cortisol in larval survival. I have also shown that cortisol has no role in either collagen deposition or the angiogenic response in Balb/c mice under the experimental conditions detailed here.
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AMARANTE, Cristina Fernandes do. "Fatores associados ? agrega??o, ? abund?ncia e ? domin?ncia parasit?ria em peixes coletados no Estado do Rio de Janeiro, Brasil: um enfoque ecoepidemiol?gico." Universidade Federal Rural do Rio de Janeiro, 2016. https://tede.ufrrj.br/jspui/handle/jspui/1325.
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CNPq
This study aimed to assess the factors involved in the determination of ecological events, including parasite aggregation, abundance, and dominance, via multivariate analysis using fish as a biological model. For this purpose, we used a database consisting of 3,746 fish specimens collected on the coast of Rio de Janeiro and from the Guandu river and evaluated their characteristics, habits, and associated parasites. Parasites were grouped into seven higher taxa: Nematoda, Monogenea, Cestoda, Trematoda, Acanthocephala, Hirudinea, and Crustacea. Aggregation was calculated using the dispersion index; abundance was determined by calculating the total number of parasites; and dominance was calculated using the Berger-Parker index. Data normality was tested using the Shapiro-Wilk test; group comparisons, when necessary, were performed using the Wilcoxon test or the Kruskal-Wallis test. Adjustments were made in the linear regression models for parasite aggregation in each parasite taxon evaluated and in the mixed-effect models to evaluate abundance and dominance using Poisson and Gaussian distributions, respectively. The factors inherent to the hosts, including sex, size, habitats, formation of schools, eating habits, and aquatic environments, were tested as potential explanatory variables of these ecological events. In addition, the parasite development stage and parasite taxa were included as explanatory variables in the analysis of the determinants of aggregation and dominance, respectively. In the mixed-effects model, the ecological events were considered an outcome variable, and fish species were considered a random variable. Regression coefficients were calculated in the study of aggregation, and parasite dominance and prevalence rate were estimated in the study of abundance. Significance was determined using confidence intervals (CI) and the Wald test. All calculations were performed using R software with a confidence interval of 95%. Statistically significant associations between levels of parasite aggregation and explanatory variables (factors inherent to the host and the percentage of larvae) varied according to the parasite taxon. The coefficient of determination was lower than 60% in all of the adjusted models, indicating that factors other than those analyzed may be associated with the level of parasite aggregation. Parasite abundance was significantly associated with sex, formation of schools, habitats, and host length, which were considered risk factors. The numerical dominance of parasites was significantly associated with host length and the taxa Nematoda, Trematoda, Monogenea, Hirudinea, and Crustacea. In addition, our results indicate that the mixed-effects model was more parsimonious compared with the classical model, underscoring the importance of choosing a statistical model that takes into consideration the nature of the data to avoid spurious results, especially when autocorrelations data were not considered. In general, our results point to the need for developing studies with more comprehensive databases and larger samples of parasite species, in which data on the life cycles of fish species and parasite taxa can be analyzed more thoroughly.
Este trabalho teve como objetivo avaliar fatores envolvidos na determina??o dos eventos ecol?gicos: agrega??o, a abund?ncia e a domin?ncia parasit?ria por meio de an?lises multivariadas, utilizando peixes como modelo biol?gico. Para tanto, foi utilizado um banco de dados composto por 3.746 esp?cimes de peixes, suas caracter?sticas e h?bitos e seus parasitos, provenientes do litoral do Rio de Janeiro e do Rio Guandu. Os parasitos foram agrupados em sete t?xons superiores: Nematoda, Monogenea, Cestoda, Trematoda, Acanthocephala, Hirud?nea e Crust?cea. A agrega??o foi calculada atrav?s do ?ndice de dispers?o; a abund?ncia pela quantidade total de parasitas computados; e a domin?ncia atrav?s do ?ndice de Berger Parker. A normalidade dos dados foi testada pelo teste de Shapiro Wilk e a compara??o de grupos, quando necess?ria, foi realizada pelo teste de Wilcoxon ou Kruskal-Wallis. Foram ajustados modelos de regress?o linear para a agrega??o parasit?ria para cada t?xon parasit?rio estudado e modelos de efeitos mistos para an?lise dos determinantes da abund?ncia e da domin?ncia, com distribui??o de Poisson e gaussiana, respectivamente. Os fatores inerentes aos hospedeiros tais como: sexo, tamanho, habitat, forma??o de cardumes, h?bitos alimentares e ambiente aqu?tico foram testados como poss?veis vari?veis explicativas desses eventos ecol?gicos. Al?m desses, na an?lise dos determinantes da agrega??o e domin?ncia foram inclu?dos os fatores est?dio de desenvolvimento do parasita e os t?xons parasit?rios como vari?veis explicativas, respectivamente. Os eventos ecol?gicos foram considerados vari?veis desfecho e nos modelos mistos a esp?cie de peixe como vari?vel aleat?ria. Foram calculados os coeficientes de regress?o nos estudos de agrega??o e domin?ncia parasit?ria e estimada a raz?o de preval?ncia no estudo de abund?ncia. A signific?ncia foi verificada por meio o intervalo de confian?a (IC) e do teste de Wald. Todos os c?lculos foram realizados utilizando o software R, com um IC de 95%. As associa??es estatisticamente significativas entre o n?vel de agrega??o parasit?ria e as vari?veis explicativas (fatores inerentes ao hospedeiro e propor??o de larvas) variaram conforme o t?xon parasit?rio. O coeficiente de determina??o foi inferior a 60%, em todos os modelos ajustados, indicando que outros, fatores al?m dos analisados, devam estar relacionados ao grau de agrega??o parasit?ria. A abund?ncia parasit?ria mostrou-se associada significativamente ?s vari?veis: sexo, forma??o de cardumes, habitat e comprimento do hospedeiro, que se comportaram como poss?veis fatores de risco. A domin?ncia num?rica de parasitos esteve associada significativamente ao comprimento do hospedeiro e aos t?xons Nematoda, Trematoda, Monogenea, Hirud?nea e Crust?cea. Os resultados mostraram que os modelos mistos foram mais parcimoniosos em rela??o aos modelos cl?ssicos, refor?ando a import?ncia da escolha de um modelo estat?stico mais adequado ? natureza dos dados, evitando-se resultados esp?rios, principalmente quando n?o se leva em conta a autocorrela??o dos dados..De um modo geral, os resultados deste estudo sinalizam para a necessidade de pesquisas com bancos de dados mais abrangentes e com amostras maiores de esp?cies de parasitos, nos quais as caracter?sticas do ciclo biol?gico das esp?cies de peixes e dos t?xons parasit?rios possam ser mais detalhados nas an?lises.
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De, Garine-Wichatitsky Michel de. "Ecologie des interactions hôtes/vecteurs : analyse du système tiques/ongulés sauvages et domestiques en zone tropicale." Montpellier 2, 1999. http://www.theses.fr/1999MON20114.
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Les hotes peuvent-ils eviter les parasites ? dans une perspective ecologique et evolutive, nous avons etudie l'infestation des ongules par des tiques, ainsi que la distribution spatio-temporelle de ces vecteurs et de leurs hotes. Un modele theorique est presente qui relie (1) les niveaux d'infestation des ongules ; a (2) l'utilisation de l'habitat par les ongules ; et (3) l'abondance des tiques dans la vegetation. Les parametres du modele ont ete mesures sur un ranch mixte faune/betail du zimbabwe en fonction des saisons : (1) les niveaux d'infestation sont variables entre les especes d'ongules ; (2) l'utilisation de l'habitat par les ongules differe entre les especes, mais ne semble pas expliquer les variations d'infestation entre especes ou entre individus-hotes ; (3) l'abondance des larves de tiques dans la vegetation revele deux distributions garantissant le contact avec les ongules : une distribution imprevisible dans le temps et l'espace, et donc inevitable ; une distribution previsible, mais inevitable car associee a des ressources indispensables aux hotes (points d'eau et ressources fourrageres). Les strategies eventuelles d'evitement des tiques par les ongules sont abordees en fonction des compromis qu'elles impliquent pour les hotes, de la previsibilite du risque parasitaire, et de l'agregation des parasites a differentes echelles. Les tiques et les maladies a tiques constituent un frein majeur au developpement de l'elevage en zone tropicale. De plus, face a la multiplication des conflits entre la faune et les activites pastorales en afrique (competition pour les paturages et transmission de maladies), les systemes mixtes faune/betail permettent de concilier des objectifs de conservation et de productions animales. Nos resultats sont discutes en relation avec la spatialisation du risque vectoriel, les methodes de lutte contre les tiques, et l'interet d'une etude genetique des vecteurs pour etablir le role de reservoir eventuel de la faune sauvage.
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Alqaisi, Amjed Qays Ibrahim. "Functional analyses of sphingolipid biosynthesis in an apicomplexan parasite." Thesis, Durham University, 2018. http://etheses.dur.ac.uk/12449/.
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The phylum Apicomplexa includes many protozoan parasites that cause serious human and animal disease, for example Plasmodium, Eimeria and Toxoplasma. Treatments against these parasites are limited and novel solutions are urgently required. Recently, research has focused on parasite specific features of lipid biosynthesis as drug targets. In particular the biosynthesis of sphingolipids, which have essential roles in many processes, has been highlighted as a potential target. Using the model apicomplexan Toxoplasma gondii we are studying the role of parasite and host sphingolipid biosynthesis in invasion and proliferation. Serine palmitoyltransferase (SPT) catalyzes the first step in sphingolipid biosynthesis, and our results demonstrated that the expression of host cell SPT is unaffected by Toxoplasma infection. In mammals the primary complex sphingolipid is sphingomyelin (SM), again our data demonstrated that the SM synthases (1 and 2) are not influenced by infection. Together these data indicated that parasite manipulation of host sphingolipid biosynthesis does not occur, supporting the hypothesis that Toxoplasma is dependant on de novo sphingolipid biosynthesis. To characterise this pathway, we showed that the Toxoplasma TgSPT1 and 2 are, like other eukaryotes, localised and active in the endoplasmic reticulum. However, uniquely, they have a prokaryotic origin. Metabolic labelling showed that several distinct complex sphingolipids are synthesized independently by the parasite. The fungal inositol phosphorylceramide (IPC) synthase inhibitor aureobasidin A (AbA) has been reported to target Toxoplasma IPC synthesis. However, our results demonstrated that whilst AbA, and an orthologue, are active against the parasite, their effect on Toxoplasma de novo sphingolipid biosynthesis is negligible. In addition, by using Leishmania major as a model we have analysed the global effect of compounds recognised as IPC synthase inhibitors in this kinetoplastid protozoan parasite. The results showed that ceramide levels increased in treated parasites, perhaps leading to parasite death via secondary signalling dysfunction. These data confirmed that the sphingolipid biosynthetic pathway is targeted by these anti-leishmanial compounds. Finally, the anti-leishmanial drug miltefosine showed reduced activity against a transgenic strain of L. major lacking sphingolipid biosynthesis ΔLCB2 compared to wild type. This suggested the sphingolipid synthesis has a role in sensitivity to the drug, metabolomic analyses supported this. Taken together, the present findings further characterised the T. gondii sphingolipid biosynthetic pathway and indicated the potential to target this in drug discovery efforts. In addition, metabolomic and lipidomic approaches confirmed that clemastine targets L. major IPCS.
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Jarvis, Lisa Marie. "A biochemical analysis of the antigens of Trichinella spiralis." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334833.
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Wawrzyniak, Ivan. "Génomique et post-génomique du parasite intestinal Blastocystis sp. sous-type 7. Evaluation de son pouvoir pathogène." Thesis, Clermont-Ferrand 2, 2012. http://www.theses.fr/2012CLF22243/document.
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Blastocystis spp. est un Straménopile parasite anaérobie fréquemment rencontré dans le tractus gastro-intestinal de l’homme et de divers animaux. Ce parasite est associé à des troubles gastro‐intestinaux aspécifiques, et semble impliqué dans des désordres fonctionnels tels que le syndrome de l’intestin irritable (IBS). Ce travail de thèse s’appuie sur le séquençage du génome de Blastocystis sp. ST7 réalisé en collaboration avec le Génoscope d’Evry, l’Université Nationale de Singapour, l’Institut Pasteur de Lille et l’Université de Provence. Ce génome est constitué d’un génome nucléaire de 18,8 Mpb pour 6020 gènes, et d’un génome mitochondrial de 29 kpb localisé dans des organites apparentés aux mitochondries. L’analyse de ce génome apporte des informations au niveau de l’évolution de ce microorganisme, de son adaptation à l’environnement intestinal et de ces facteurs de virulence potentiels. En effet, les analyses in silico de ce génome ont montré que Blastocystis sp. ST7 possède plusieurs gènes codant des protéines pouvant agir à l’interface entre l’hôte et le parasite et connues chez d’autres protozoaires pour être impliquées dans des phénomènes de pathogénie. Ce sont en particulier des PKS, des NRPS, et des hydrolases dont des protéases. D’autre part, des activités protéolytiques ont été mises en évidence expérimentalement dans les surnageants de culture du parasite. Deux protéases à cystéines (une cathepsine B et une légumaïne) pouvant être impliquées dans la physiopathologie du parasite, ont été identifiées et caractérisées dans les surnageants, confirmant ainsi nos analyses in silico. Ce travail ouvre de nombreuses pistes intéressantes à explorer pour évaluer l’impact de ce parasite en santé humaineBlastocystis spp. is a highly prevalent anaerobic Stramenopile parasite found in the intestinal tract of humans and various animals. This parasite is associated with non specific intestinal disorders, and could be involved in functional disorders such as the irritable bowel syndrome (IBS). In this work, the Blastocystis sp. ST7 genome sequencing project was carried out in collaboration with the Génoscope of Evry, the National University of Singapore, the Pasteur Institute of Lille and the University of Provence. This genome consists in a nuclear genome of 18,8 Mpb encoding 6020 genes, and a mitochondria‐like genome of 29 kpb localised in the mitochondrion‐like organelles. The analysis of this genome brings information about the evolution of this micro‐organism, its adaptation to the intestinal environment and its potential virulence factors. Blastocystis sp. ST7 was predicted to harbor several genes coding proteins that could act at the parasite‐host interface, and that are known to be involved in the pathogeny of many protozoa. They are PKS, NRPS, and hydrolases among them proteases. In addition, proteolytic activities were highlighted in the parasite culture supernatants. Two cysteine proteases (a cathepsin B and a legumain) were identified and characterized from the supernatants and could play a role in the physiopathology of the parasite, that confirm our in silico analyses. This work opens new ways to evaluate the impact of this parasite in human health
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Vermont, Sarah J. "Proteomic and transcriptomic analysis of the protozoan parasite Neospora caninum." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/11637/.
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Neospora caninum is an economically significant parasitic protozoan causing the disease neosporosis in cattle and dogs. Although a close relative of the zoonotic apicomplexan Toxoplasma gondii, the two organisms exhibit differing host ranges and infection dynamics. T. gondii is a model organism that has been much studied, and a great deal is known about the genes and proteins involved when it invades a host cell. This thesis explores protein expression in the proliferative and invasive tachyzoite stage of N. caninum, in particular the expression of proteins pertaining to the apical complex of organelles; those responsible for entry and establishment within a host cell. Almost 20 % of the predicted proteome has been identified by this analysis to be expressed in the tachyzoite stage, with approximately 50 % of the predicted repertoire of apical proteins being detected. The discovery of differences between these two parasites’ highly syntenic genomes could lead to a better understanding of the process by which T. gondii is able to cause disease in humans, while N. caninum has not been observed to do so. One finding of the recent genome sequencing and annotation project in N. caninum was that a key T. gondii virulence determinant, rhoptry gene 18 (ROP18) was pseudogenised in N. caninum. This finding was investigated further in this thesis to demonstrate that the pseudogenisation of ROP18 was conserved across a range of N. caninum isolates and that in vitro, N. caninum was not able to subvert the murine interferon-gamma (IFN-γ) immune response using ROP18 in the way that virulent T. gondii tachyzoites do. The tissue-dwelling Coccidia have a multi-stage life cycle which includes a latent tissue cyst-encapsulated stage called the bradyzoite. Tachyzoites convert to this more quiescent form when induced by cellular stress, and are able to remain as such for long periods, even years. At times of weakened host immunity, bradyzoites can recrudesce to produce an active infection, which can cross the placenta in a pregnant animal to infect the foetus. This a major route by which N. caninum infection is maintained within cattle herds, therefore the biology of stage conversion from tachyzoite to bradyzoite and vice-versa is of interest to researchers. An RNA-Seq analysis of cultured tachyzoites and bradyzoites identified a marked reduction in rhoptry gene expression, and differing expression profiles of other invasion-related genes from the micronemes and dense granules. Overall, these data identify proteins released from the apical organelles in N. caninum and give an insight into the different repertoires expressed by the tachyzoite and bradyzoite life stages. Furthermore, a comparison between N. caninum and T. gondii predicted apical proteomes indicates that although most genes are shared in a one-to-one orthologous relationship between the two organisms, there are a small number of differences which may turn out to be important to the biology of the parasite, as in the case of ROP18.
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Goyet, Vincent. "Analyse transcriptomique globale et génétique fonctionnelle chez la plante parasite Phelipanche ramosa." Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4032/document.
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Les plantes sont connues pour être des organismes autotrophes mais au cours de l’évolution certaines d’entre elles ont opté pour un mode vie parasitaire. La clé de cette transition repose sur l’apparition d’un organe permettant la mise en place de l’interaction entre la plante parasite et la plante hôte : l’haustorium. La formation de cet organe chez les Orobanchaceae hémiparasites (photosynthétiques) peut être induite en réponse à des facteurs inducteurs d’haustorium (HIF) issus de la dégradation des parois racinaires de l’hôte. Chez les holoparasites (non photosynthétiques) tels que les orobanches, l’induction haustoriale demeure un processus mal compris du fait de l’absence d’activité des HIF connus. Ces travaux de thèse montrent que l’haustoriogenèse chez l’Orobanchaceae holoparasite Phelipanche ramosa est induite par des molécules contenues dans les exsudats racinaires de son hôte, le colza. L’établissement d’un transcriptome de référence et une analyse de la réponse transcriptomique globale des graines germées de P. ramosa en réponse aux exsudats de colza suggèrent l’établissement d’une signalisation hormonale. Le fractionnement HPLC ainsi que des analyses UPLC-MS montrent la présence d’un composé de type cytokinine dans la fraction la plus active des exsudats. En parallèle, l’activité inductrice d’haustorium des cytokinines a été démontrée proposant un rôle majeur de ces phytohormones lors de l’haustoriogenèse chez P. ramosa. Ce travail de thèse a également permis de cultiver P. ramosa en l’absence de l’hôte par la mise en place de lignées de cals, et également d’établir une méthode de transformation génétique permettant des approches de validation fonctionnelleAlthough plants are known to be autotrophic organisms, some of them have adopted a parasitic lifestyle in the course of evolution. One of the major feature of this transition lies in the apparition of a novel organ, the haustorium, which allows the establishment of the interaction between the parasitic plant and its host. The formation of this organ in hemiparasitic Orobanchaceae (photosynthetic) is induced in response to haustorium inducing factors (HIF) derived from the degradation of host roots cell walls. In holoparasites (not photosynthetic) such as broomrapes, this process remains misunderstood due to the inactivity of the known HIF. This Ph.D. work shows that the haustoriogenesis in the harmful holoparasite Phelipanche ramosa, is induced by molecules contained in root exudates of its host Brassica napus. The establishment of a reference transcriptome and the analysis of the transcriptomic response of germinated seeds of P. ramosa in response to B. napus root exudates both suggest the involvement of hormonal signaling. The HPLC fractionation of root exudates along with UPLC-MS analysis identified a cytokinin-like compound in the most active fraction. Furthermore, this work demonstrates that cytokinins induce haustorium differentiation in vitro, suggesting a major role of this phytohormone during the haustorium formation in P. ramosa. Moreover, this work allowed to set a host-free culture system of P. ramosa by developing calli lines, and to develop of a transformation system allowing functional validation approaches
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Lendner, Matthias. "Functional analysis of tropomyosin of parasitic nematodes." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2010. http://dx.doi.org/10.18452/16137.
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Parasitische Würmer gehören mit über 3,5 Milliarden Betroffenen zu den weltweit verbreitetesten Infektionskrankheiten. Der Erfolg dieser Parasiten beruht auf ihren ausgefeilten Mechanismen mit denen sie das Immunsystem ihrer Wirte manipulieren. Interessanter Weise gehen Wurminfektionen mit einer geringeren Wahrscheinlichkeit an Allergien zu erkranken einher. Wie genau die Parasiten das Immunsystem manipulieren ist weitgehend unbekannt. Um diese Mechanismen besser studieren zu können, wurde im Rahmen dieser Arbeit versucht RNA interference (RNAi), anhand des Modellmoleküls Tropomyosin zu etablieren. Wie sich am Beispiel des Strongyliden Heligmosomoides polygyrus bakeri zeigte, ist RNAi als Manipulationsmethode für Nematoden nicht oder nur in geringem Maße geeignet. Dies lässt sich auf das Fehlen von Aufnahme- und Verbreitungsmechanismen für Doppelstrang-RNA zurückführen. Desweiteren wurden die Auswirkungen von rekombinantem Tropomyosin der Filarie Acanthocheilonema viteae (rAv-TMY) auf die Entstehung allergischer Atemwegserkrankungen im Mausmodell untersucht. Eine viermalige Behandlung mit rAv-TMY in einem Zeitraum von vier Wochen führte zu verringerten entzündlichen Reaktionen in den Atemwegen. Die Analyse immunologischer Parameter ergab, dass rAv-TMY signifikant den Einstrom von Entzündungszellen in die Atemwege reduziert, allem voran den Einstrom von Eosinophilen. Dies lässt sich durch die verringerte Ausschüttung an IL-5, Eotaxin und MCP-5 zurückführen. Zudem wurde die Bildung von antigenspezifischen IgE verringert während sich die Produktion blockierender IgG1 Antikörper erhöhte. Diese Arbeit belegt somit die anti-allergischen Eigenschaften von rAv-TMY. Damit stellt rAv-TMY ein interessantes Kandidatenmolekül zur Behandlung allergischer Reaktionen dar. Desweiteren kann der Vergleich von allergenem, nicht allergenem und modulatorischem Tropomyosin wichtige Informationen über die allgemeinen Eigenschaften von Allergenen und ihrer molekularen Struktur geben.Parasitic worms are among the world''s most prevalent infectious diseases with more than 3.5 billion. The success of these parasites is based on their sophisticated ways to manipulate the immune system of their hosts. Interestingly, worm infections abate the risk to develop allergic disorders. How exactly parasitic worms modulate the immune system is so far largely unknown. In order to be able to investigate parasite induced modulation, this work aimed to establish RNA interference (RNAi), a method of genetic manipulation, using tropomyosin as target gene. As shown for the example of Heligmosomoides polygyrus RNAi is not or only to a small extent useful as method to genetically manipulate nematodes. This can be explained with the lack of uptake and spreading mechanisms for double stranded RNA. Furthermore, this work examined the impact of the recombinant muscle protein tropomyosin of Acanthocheilonema viteae (rAv-TMY) on the course of a rodent model of allergic airway inflammation. A four-time treatment with rAv-TMY over a period of four weeks resulted in decreased inflammatory responses in the airways. The analysis of immunological parameters showed that rAv-TMY significantly reduces the influx of inflammatory cells into the airways, especially eosinophils. The reduced eosinophil influx can be attributed to the decreased expression of IL-5, eotaxin and MCP-5 in the airways. In addition, the formation of antigen-specific IgE was impaired whereas the production of the blocking antibody IgG1 was increased. These results demonstrate the anti-allergic properties of rAv-TMY. For this reason rAv-TMY becomes an interesting model molecule for the treatment of allergic diseases. Furthermore, the comparison of allergenic, non-allergenic and modulatory tropomyosin might put some light on the nature of allergens and their molecular patterns.
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Bazzo, Jeffrey D. "Analysis of Uncontrolled Concrete Bridge Parapet Cracking." Cleveland State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=csu1351032089.
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Wasmuth, James D. "Computational analysis of proteomes from parasitic nematodes." Thesis, University of Edinburgh, 2006. http://hdl.handle.net/1842/14636.
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The focus of this thesis is the comparison of nematode proteomes. I describe my work to identify sequences and sequence features that have patterns of interest to nematode biology. Such patterns include proteins that are unique to a parasitic feeding strategy, and protein domains that have been lost in certain nematode lineages. This involved not only global comparisons of the proteomes, but also delineating the protein domain complement of each species. One vital step in the analysis is identifying credible coding regions within the error-prone EST sequences. Robust identification of the coding regions presents an opportunity to perform comparative analysis previously confined to those working with complete genomes. To achieve this, I built the translation pipeline prot4EST, a hierarchical collection of freely-available algorithms. The benchmarking showed that prot4EST produced coding region predictions that were better than its constituent algorithms. Exploring the effect of sequence composition of both the studied species and the program’s training sets improved the accuracy of prediction. A database of high quality protein translations for all nematodes studies was generated, called NemPep. This was accompanied by a collection of predicted domains (NemDom). The decoration of protein sequences with domain annotation is not trivial, especially given the incomplete nature of ESTs. It was necessary to explore domain model assignment to ensure the most accurate results. The rigorous analysis of these resources has revealed: (1) proteins specific to certain nematode lineages; (2) the level and potential effects of contamination in the original cDNA libraries; (3) the extent of protein loss and domain modification in the caenorhabditid lineage.
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Bouloux, Catherine. "Modélisation, simulations et analyse mathématique de systèmes hôtes-parasites." Bordeaux 1, 1997. http://www.theses.fr/1997BOR10626.
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Nous étudions certains systèmes hôtes-parasites. Dans les deux premières parties, les parasites sont des macroparasites Diplectanum Aequans, parasitant les bars Dicentrarchus Labrax alors que dans la troisième partie, il s'agit de microparasites, le VIF (virus d'immunodéficience féline) et le VLF (virus de la leucémie féline) infestant des populations de chats. Dans la première partie un modèle discret en temps est proposé : il n'y a pas de démographie dans les populations d'hôtes dont la mortalité est uniquement due aux parasites. On effectue des simulations numériques et nous mettons en évidence deux principales dynamiques. Dans la deuxième partie, nous construisons plusieurs modèles hôtes-parasites continus en temps avec ou sans structuration spatiale ; nous travaillons avec des classes d'hôtes ayant une certaine charge parasitaire, ce qui nous amène à un système comportant un nombre infini d'EDO ou d'EDP. Puis, grâce à des hypothèses standards simplificatrices, nous réduisons ce système en un nombre fini d'équations. Nous procédons ensuite à l'étude mathématique de certains d'entre eux : le système hôtes immatures-hôtes adultes sans parasite, les systèmes hotes-parasites à deux ou trois classes de populations. Afin de faire un lien entre le modèle discret et les modèles continus, nous étudions le modèle à trois classes de populations sans démographie des hôtes ; nous faisons l'étude du modèle d'EDO par l'analyse mathématique et les simulations numériques, puis nous le comparons avec le modèle discret. Le modèle d'EDP possède des singularités dans les termes de réaction ; l'étude d'un problème approche, nous permet d'obtenir des résultats préliminaires du problème initial. Dans la troisième partie, nous étudions un modèle mixte de viroses dans une population de chats domestiques (Felis Catus) : les virus en présence sont le VIF et le VLF. Nous obtenons un système d'EDP à six équations et nous donnons un résultat d'existence globale.
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Nirmalan, Niroshini Jacintha. "A comparative analysis of novel filarial retinol binding proteins." Thesis, University of Salford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314007.
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Sekora, Nicholas Scott Lawrence Katheryn Kay Scott. "Identification of plant-parasitic nematodes using FAME analysis." Auburn, Ala, 2009. http://hdl.handle.net/10415/1806.
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Chappell, Lia Victoria Louise. "Novel approaches for transcriptome analysis in Plasmodium parasites." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648817.
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Dwivedi, Ankit. "Functional analysis of genomic variations associated with emerging artemisinin resistant P. falciparum parasite populations and human infecting piroplasmida B. microti." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT073/document.
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Le programme d’élimination du paludisme de l’OMS est menacé par l’émergence etla propagation potentielle de parasites de l’espèce Plasmodium falciparum résistants à l’artémisinine. Récemment il a été montré que (a) des SNPs dans une région du chromosome 13 subissaient une forte sélection positive récente au Cambodge,(b) plusieurs sous-populations de parasites de P. falciparum résistants et sensibles à l’artémisinine étaient présentes au Cambodge, (c) des mutations dans le domaine Kelch du gène k13 sont des déterminants majeurs de la résistance à l’artémisinine dans la population parasitaire cambodgien et (d) des parasites de sous-populations du nord du Cambodge près de la Thaïlande et du Laos sont résistants à la méfloquine et portent l’allèle R539T du gène de k13.Il est donc nécessaire d’identifier la base génétique de la résistance dans le but de surveiller et de contrôler la transmission de parasites résistants au reste du monde, pour comprendre le métabolisme des parasites et pour le développement de nouveaux médicaments. Ce travail a porté sur la caractérisation de la structure de la population de P. falciparum au Cambodge et la description des propriétés métaboliques des sous-populations présentes ainsi que des flux de gènes entre ces sous-populations. Le but est d’identifier les bases génétiques associées à la transmission et l’acquisition de résistance à l’artémisinine dans le pays.La première approche par code-barre a été développée pour identifier des sous-populations à l’aide d’un petit nombre de loci. Une approche moléculaire de PCR-LDR-FMA multiplexée et basée sur la technologie LUMINEX a été mise au point pour identifier les SNP dans 537 échantillons de sang (2010 - 2011) provenant de 16centres de santé au Cambodge. La présence de sous-populations le long des frontières du pays a été établie grâce à l’analyse de 282 échantillons. Les flux de gènes ont été décrits à partir des 11 loci du code-barre. Le code-barre permet d’identifier les sous-populations de parasites associées à la résistance à l’artémisinine et à la méfloquine qui ont émergé récemment.La seconde approche de caractérisation de la structure de la population de P.falciparum au Cambodge a été définie sur la base de l’analyse de 167 génomes de parasites (données NGS de 2008 à 2011) provenant de quatre localités au Cambodge et récupérés à partir de la base de données ENA. Huit sous-populations de parasites ont pu être décrites à partir d’un jeu de 21257 SNPs caractérisés dans cette étude. La présence de sous-populations mixtes de parasite apparait comme un risque majeur pour la transmission de la résistance à l’artémisinine. L’analyse fonctionnelle montre qu’il existe un fond génétique commun aux isolats dans les populations résistantes et a confirmé l’importance de la voie PI3K dans l’acquisition de la résistance en aidant le parasite à rester sous forme de stade anneau.Nos résultats remettent en question l’origine et la persistance des sous-populations de P. falciparum au Cambodge, fournissent des preuves de flux génétique entre les sous-populations et décrivent un modèle d’acquisition de résistance à l’artémisinine.Le processus d’identification des SNPs fiables a été ensuite appliqué au génome de Babesia microti. Ce parasite est responsable de la babésiose humain (un syndrome de type malaria) et est endémique dans le nord-est des Etats-Unis. L’objectif était de valider la position taxonomique de B. microti en tant que groupe externe aux piroplasmes et d’améliorer l’annotation fonctionnelle du génome en incluant la variabilité génétique, l’expression des gènes et la capacité antigénique des protéines. Nous avons ainsi identifié de nouvelles protéines impliquées dans les interactions hôte-parasiteThe undergoing WHO Malaria elimination program is threatened by the emergenceand potential spread of the Plasmodium falciparum artemisinin resistant parasite.Recent reports have shown (a) SNPs in region of chromosome 13 to be understrong recent positive selection in Cambodia, (b) presence of P. falciparum parasiteresistant and sensitive subpopulations in Cambodia, (c) the evidence that mutationsin the Kelch propeller domain of the k13 gene are major determinants ofartemisinin resistance in Cambodian parasite population and (d) parasite subpopulations in Northern Cambodia near Thailand and Laos with mefloquine drugresistance and carrying R539T allele of the k13 gene.Identifying the genetic basis of resistance is important to monitor and control thetransmission of resistant parasites and to understand parasite metabolism for the development of new drugs. This thesis focuses on analysis of P. falciparum population structure in Cambodia and description of metabolic properties of these subpopulations and gene flow among them. This could help in identifying the genetic evidence associated to transmission and acquisition of artemisinin resistance over the country.First, a barcode approach was used to identify parasite subpopulations using smallnumber of loci. A mid-throughput PCR-LDR-FMA approach based on LUMINEXtechnology was used to screen for SNPs in 537 blood samples (2010 - 2011) from 16health centres in Cambodia. Based on successful typing of 282 samples, subpopulations were characterized along the borders of the country. Gene flow was described based on the gradient of alleles at the 11 loci in the barcode. The barcode successfully identifies recently emerging parasite subpopulations associated to artemisinin and mefloquine resistance.In the second approach, the parasite population structure was defined based on167 parasite NGS genomes (2008 - 2011) originating from four locations in Cambodia,recovered from the ENA database. Based on calling of 21257 SNPs, eight parasite subpopulations were described. Presence of admixture parasite subpopulation couldbe supporting artemisinin resistance transmission. Functional analysis based on significant genes validated similar background for resistant isolates and revealed PI3K pathway in resistant populations supporting acquisition of resistance by assisting the parasite in ring stage form.Our findings question the origin and the persistence of the P. falciparum subpopulations in Cambodia, provide evidence of gene flow among subpopulations anddescribe a model of artemisinin resistance acquisition.The variant calling approach was also implemented on the Babesia microti genome.This is a malaria like syndrome, and is endemic in the North-Eastern USA. Theobjective was to validate the taxonomic position of B. microti as out-group amongpiroplasmida and improve the functional genome annotation based on genetic variation, gene expression and protein antigenicity. We identified new proteins involved in parasite host interactions
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Roussel, Michaël. "Séquençage du génome du parasite intestinal Blastocystis sp. (ST7) : vers une meilleure compréhension des capacités métaboliques d'organites apparentés aux mitochondries chez ce microorganisme anaérobie." Thesis, Clermont-Ferrand 2, 2011. http://www.theses.fr/2011CLF22164/document.
Full textAbstract:
Blastocystis sp., est un straménopile parasite anaérobie fréquemment rencontré dans le tractus gastro-intestinal de l’homme et de divers animaux. Ce microorganisme, parfois responsable de désordres digestifs aigus, pourrait conduire à des troubles fonctionnels intestinaux tels que le syndrome de l’intestin irritable (IBS). Le génome de Blastocystis sp., qui a fait l'objet d'un projet de séquençage en collaboration avec le Génoscope d’Evry, nous a permis de caractériser le plus petit génome de straménopile séquencé à ce jour (18,8 Mpb), avec une capacité codante de 6020 gènes. L’acquisition de nombreux gènes par transferts horizontaux est une caractéristique majeure de ce génome, qui montre d’abondants réarrangements génomiques. Bien qu’évoluant en anaérobiose, Blastocystis sp. possède des organites morphologiquement proches des mitochondries, appelés mitochondrion-like organelles (MLOs). Nous avons montré que ces organites comportaient un génome circulaire de type mitochondrial de 29,27 kpb, mais dépourvu des gènes codant pour les cytochromes. Des analyses in silico nous ont permis de caractériser le protéome des MLOs (365 protéines), conduisant à l’établissement d’un modèle prédictif des voies métaboliques associées à ces organites, avec notamment une chaine respiratoire limitée aux complexes I et II. Nous avons ainsi montré que les MLOs présentent des caractères communs aux mitochondries anaérobies et aux hydrogénosomes (présence d’une PFOR et d’une hydrogénase à fer), suggérant que Blastocystis sp. comporte des mitochondries anaérobies modifiées, qui résulteraient d’une adaptation du parasite à son environnement. Par ailleurs, la prédiction du sécrétome de Blastocystis sp. révèle la présence de facteurs de virulence potentiels, pouvant être impliqués dans l’altération de l’épithélium intestinal et le contournement du système immunitaire de l’hôteBlastocystis sp. is a highly prevalent anaerobic eukaryotic stramenopile parasite found in the intestinal tract of humans and various animals. This microorganism, sometimes associated with acute intestinal disorders, could be responsible for functional intestinal disorders such as the irritable bowel syndrom (IBS). As part of a collaborative sequencing project with the Genoscope (CEA Evry, France), we were able to caracterize the smallest stramenopile genome sequenced to date (18.8 Mbp) with a 6020 genes coding capacity. The gain of many genes through horizontal gene transfer is amajor characteristic of this genome, which shows extensive genomic rearrangements. Despite the anaerobic nature of Blastocytists sp., this eukaryote harbours nevertheless mitochondrion-like organelles (MLOs). We have shown that these organelles have a 29.27 kbp mitochondrial-type circular genome that lacks cytochrome coding genes. In silico analysis allowed us to predict the MLOs proteome (365 proteins), with the subsequent predictive model of the metabolic pathways associated with these organelles, including an electron transport chain (ETC) restricted to complex I and II. We have shown that MLOs shared common characteristics with anaerobic mitochondrion and hydrogenosomes (presence of a PFOR and an iron-hydrogenase), which could mean that Blastocystis sp. harbours modified anaerobic mitochondrion that resulted from the parasite adaptation to its anaerobic environment. In addition, Blastocytis sp. secretome prediction reveals the presence of potential virulence factors, which could be involved in the degradation of the intestinal epithelium as well as the host immune system bypass
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Hoogendoorn, Bastiaan. "Eimeria tenella genome analysis : initiation of a physical map with chromosome 2." Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267441.
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Broad, Gavin Roy. "Phylogenetic analysis of host utilisation patterns in parasitoid hymenoptera." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368910.
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Ponce, Maiza Campos. "A molecular analysis of Leishmania chagasi and Leishmania infantum tropisms." Thesis, Keele University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344098.
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Geysen, Dirk. "The application of molecular biology techniques to analyse diversity in Theileria parva populations in Zambia." Thesis, Brunel University, 2000. http://bura.brunel.ac.uk/handle/2438/5303.
Full textAbstract:
Theileria parva is a complex protozoan parasite causing East Coast fever in Eastern and Central Africa. Vaccination using live parasites is an effective control measure and has been used in Zambia based on locally isolated and introduced T. parva stocks. Diversity among T. parva populations was investigated in parasites from two Zambian provinces with different disease epidemiologies and control histories. Isolates from the pre-vaccination era, local and exotic stocks used for vaccination, and one recent field isolate were cloned and passaged in vitro to study genomic stability over time. The results of the data from three genome-wide probes indicate a marked homogeneity and stability among the Zambian isolates in contrast to East African isolates. Results from Southern blot profiles and the polymorphic immunodominant molecule (PIM) sequence analysis suggest a common origin for the Zambian isolates from the pre-vaccination era, except for one isolate (Zam5) from Southern Province. This isolate showed characteristics suggesting a buffalo origin. Assays for genotype characterisation were developed using five allelic markers. Multilocus characterisation revealed identical profiles in a recent Zambian isolate from Southern Province and two components of an exotic cocktail vaccine, indicating the escape of one of the vaccine stocks in the field. Characterisation of T. parva field populations by RFLP-PCR assays after immunisation revealed the presence of dominant genotypes from those that had been used for vaccination. Circumstantial evidence for the involvement of one of the exotic vaccine parasites in epidemics in Southern Province is presented and a hypothesis formulated for the rapid spread of this genotype. Analysis of the characterisation data suggested the existence of two groups of T. parva parasites of different origin. The classic T. parva group, characterised by a dimorphism of the p150, p104 and p32 loci and the absence of a p67 insert and a buffalo-derived group which showed a polymorphism of p150, p104 and p32 and the presence of a p67 insert. There is evidence that recombination occurs, resulting in parasites that have characteristics of both groups. The relevance of these recombinant parasites in the epidemiology of the disease seems low. Characterisation of larger samples from areas of regular buffalo-cattle contact is necessary to clarify this. Sequence analysis of the most discriminative locus (PIM) was undertaken and gene conversion could be the main mechanism generating diversity. A more appropriate nomenclature for T. parva is proposed based on the growing evidence of molecular differences among isolates and stocks.
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Jewell, Kelly Jean. "Landscape analysis of distribution and demographic consequences in a brood parasite-host system." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31399.
Full textAbstract:
Source-sink dynamics may occur where variation in predation or parasitism is
sufficient to cause spatial variation in population performance. Brood parasitic brownheaded
cowbirds Molothrus ater locally reduce host reproductive success, but little is
known about their regional effects on demography. I aimed to predict, using detailed
empirical data, the effect of cowbirds on the spatial dynamics of a preferred host, the
song sparrow Melospiza melodia. My objectives were to: (1) predict the distributions of
parasite and host based on landscape features; (2) predict parasitism rates from cowbird
occurrence and relate this to sparrow fecundity; and (3) map expected population growth
rates (λ) for song sparrows given parasitism, testing if spatial refuges from parasitism
exist.
I used logistic regression to predict cowbird occurrence by analyzing >500 avian
point counts in the Southern Gulf Islands (SGI), BC. I also evaluated alternate
hypotheses for landscape features thought to influence cowbird distribution elsewhere.
Cowbird occurrence in the SGI was best predicted by proximity to potential feeding areas
and landcover. The best logistic model included landcover, cattle, and distance to urban
and agriculture. Autologistic regression improved model performance, and models using
widely available data performed only slightly worse than those including all data. All
models of cowbird occurrence compared favorably with parasitism rates observed in 12
populations studied from 1 -8 years.
To estimate the regional effect of cowbirds, I employed data from 10 islands
studied from 2-8 years to estimate λ in song sparrow populations subject to parasitism.
Predicted growth rates were strongly influenced by cowbird distribution and land use, and were consistent with independent estimates of local population trend and findings relating
parasitism rates to landscape features elsewhere in their range.
My results suggest that the ratio of source to sink populations within a study
region will depend on land use patterns, their effect on cowbird distribution, and the
influence of parasitism on host reproduction. I use my results to suggest improvements
for future habitat modelling studies, management to limit cowbird distribution and
identify host refuges, and an approach to estimate the regional effect of enemies on the
spatial population demography of species of conservation concern.Forestry, Faculty of
Graduate
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au, Constantine@wehi edu, and Clare Constantine. "Molecular markers, analysis and the population genetics of parasites." Murdoch University, 2002. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050817.102006.
Full textAbstract:
In this study different molecular techniques are contrasted (RAPD's, allozyme, sequencing mtDNA, sequencing ribosomal spacers) and appropriate analytical methods (allelic and infinite-sites approaches; inbreeding and coalescent models) used for estimating population genetic parameters in parasites. A range of population genetic questions at different scales were chosen to emphasise the importance of tailoring techniques and analytical methods to the particular question being investigated.
The realisation that each question formulated has a particular scale means the appropriate technique and markers must be useful at that scale to attempt to answer the question. The useful scale of a technique depends several factors including the region of DNA examined, the density of sampling of the technique, and the mode of evolution of the markers. Each technique will produce a useful range of variability. Below the lower limit there is no variation, above the upper limit the variation is too high to produce useful comparisons.
Parasites are of interest for many reasons, primarily because they can cause disease and thus impact on their host's population dynamics. They are often closely associated with their hosts and may undergo co-evolution, as well as causing an ongoing immunological "arms race" with their hosts. The parasitic mode of live is found throughout nearly all taxonomic groupings and thus classical models of population genetics based on sexual, diploid vertebrates do not fit well with the entire diversity of parasite groups.
Genetic diversity within and among populations of Echinococcus granulosus was examined contrasting a RAPD dataset with an allozyme dataset. Two models of variation in Echinococcus have been proposed, those of Smyth and Rausch, and the expected genetic structure from each was compared to the observed genetic structure. The premise of Smyths model, predominant self-fertilisation, was supported, but the resultant pattern of genetic variation followed Rauschs model.
RAPD data, being dominant, present challenges to analysis. An approach to overcome this dominance problem and allow standard allelic frequency analysis is described using the selfing rate estimated from allozyme data. The RAPD data were also analysed using both band-sharing and nucleotide diversity approaches.
A population genetic study of Ostertagia ostertagi in the USA was extended to two different scales: within an Australian state and between the USA and Australian continents. Three alternative explanations for the observed discrepancy between genetic structure and differentiation in an important biological trait, hypobiosis, were explored. A number of programs and analyses were compared including coalescent geneflow estimates.
Variation among multiple copies of two spacer regions of rDNA was examined within individuals of Ostertagia ostertagi. Both the intergenic spacer and internal transcribed spacer 1 regions were found to include repeat regions, with different numbers of repeats creating length differences in clones from the same worm. Multi-copy genes present extra challenges in analysis to ensure that only homologous copies are being compared. Many studies fail to look for variation within populations or within individuals.
The two major conclusions from these examples are that:
1). The study of variation necessarily involves an implicit scale, and markers must be chosen that are appropriate to the question being explored.
2). Using several methods of analysis of genetic data allows contrasts to be made, and if different methods produce similar results gives much more confidence in the conclusions drawn. Incongruence in results leads to new questions and reexamination of the assumptions of each analysis.
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Constantine, Clare. "Molecular markers, analysis and the population genetics of parasites." Constantine, Clare (2002) Molecular markers, analysis and the population genetics of parasites. PhD thesis, Murdoch University, 2002. http://researchrepository.murdoch.edu.au/662/.
Full textAbstract:
In this study different molecular techniques are contrasted (RAPD's, allozyme, sequencing mtDNA, sequencing ribosomal spacers) and appropriate analytical methods (allelic and infinite-sites approaches; inbreeding and coalescent models) used for estimating population genetic parameters in parasites. A range of population genetic questions at different scales were chosen to emphasise the importance of tailoring techniques and analytical methods to the particular question being investigated.
The realisation that each question formulated has a particular scale means the appropriate technique and markers must be useful at that scale to attempt to answer the question. The useful scale of a technique depends several factors including the region of DNA examined, the density of sampling of the technique, and the mode of evolution of the markers. Each technique will produce a useful range of variability. Below the lower limit there is no variation, above the upper limit the variation is too high to produce useful comparisons.
Parasites are of interest for many reasons, primarily because they can cause disease and thus impact on their host's population dynamics. They are often closely associated with their hosts and may undergo co-evolution, as well as causing an ongoing immunological "arms race" with their hosts. The parasitic mode of live is found throughout nearly all taxonomic groupings and thus classical models of population genetics based on sexual, diploid vertebrates do not fit well with the entire diversity of parasite groups.
Genetic diversity within and among populations of Echinococcus granulosus was examined contrasting a RAPD dataset with an allozyme dataset. Two models of variation in Echinococcus have been proposed, those of Smyth and Rausch, and the expected genetic structure from each was compared to the observed genetic structure. The premise of Smyth's model, predominant self-fertilisation, was supported, but the resultant pattern of genetic variation followed Rausch's model.
RAPD data, being dominant, present challenges to analysis. An approach to overcome this dominance problem and allow standard allelic frequency analysis is described using the selfing rate estimated from allozyme data. The RAPD data were also analysed using both band-sharing and nucleotide diversity approaches.
A population genetic study of Ostertagia ostertagi in the USA was extended to two different scales: within an Australian state and between the USA and Australian continents. Three alternative explanations for the observed discrepancy between genetic structure and differentiation in an important biological trait, hypobiosis, were explored. A number of programs and analyses were compared including coalescent geneflow estimates.
Variation among multiple copies of two spacer regions of rDNA was examined within individuals of Ostertagia ostertagi. Both the intergenic spacer and internal transcribed spacer 1 regions were found to include repeat regions, with different numbers of repeats creating length differences in clones from the same worm. Multi-copy genes present extra challenges in analysis to ensure that only homologous copies are being compared. Many studies fail to look for variation within populations or within individuals.
The two major conclusions from these examples are that:
1). The study of variation necessarily involves an implicit scale, and markers must be chosen that are appropriate to the question being explored.
2). Using several methods of analysis of genetic data allows contrasts to be made, and if different methods produce similar results gives much more confidence in the conclusions drawn. Incongruence in results leads to new questions and reexamination of the assumptions of each analysis.
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Constantine, Clare Colleen. "Molecular markers, analysis and the population genetics of parasites /." Access via Murdoch University Digital Theses Project, 2002. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20050817.102006.
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James, Christopher Joseph. "Analysis of parasitic losses in heavy duty diesel engines." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74921.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 123-129).
Fuel economy of large, on-road diesel engines has become even more critical in recent years for engine manufactures, vehicle OEMs, and truck operators, in view of pending CO2 emission regulations. Demands for increased fuel economy are coupled with corresponding improvements in engine performance, durability, and emissions. This project centers on resolving the adverse effects on engine wear, durability, emissions, and oil consumption that often accompany traditional low-friction concepts. A detailed analysis of the sources of friction within a heavy-duty diesel engine was undertaken and empirical data on engine friction and component wear was collected from industry as well as from studies in literature. The use of thermal barrier coatings (TBC) was investigated as a novel approach to strategically increase cylinder liner temperatures in order to reduce power cylinder friction. By coating selected parts of the liner where piston speeds are high, local liner temperature is raised and local lubricant viscosity decreased in that region. In the mid-stroke, the piston is in the hydrodynamic lubrication regime, and high surface speeds generate the majority of the power cylinder work losses which can be reduced through reduced lubricant viscosity. By coating the liner in selected regions only, top dead center temperatures are mostly unaffected thereby minimizing any increase in cylinder liner wear. This approach is expected to maximize friction reduction while minimizing risk to other engine components or increasing component wear rates. A simulation was developed to model the primary physical processes that occur in a complete four stroke engine cycle. Calculations included work done by the piston, mass flow rates through the intake and exhaust valves, heat release during combustion, and heat transfer rates. The results demonstrate the potential to decrease power cylinder between 15% and 30% depending on coating thickness and application zone. This corresponds to approximately a 0.5% to 1% improvement in vehicle fuel economy. Additional fuel economy benefits from the TBC are expected from increased exhaust gas enthalpy and reduced liner heat rejection. This strategic thermal management approach within the engine has very high potential to increase engine efficiency while maintaining the performance and durability demanded in the HD engine market.
by Christopher Joseph James.
S.M.
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Correa, Yepes Ana Cristina. "Analyse de linteraction hôte-parasite sous différentes approches évolutives : le système Lymnaeidae (Gastropoda) Fasciolidae (Trematoda)." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20156.
Full textAbstract:
Les parasites exercent une pression de sélection quasiment universelle. Cette thèse aborde les relations hôte-parasite dans le système Lymnaeidae (Gastropoda) Fasciolidae (Trematoda, douves) sous différents aspects, afin de brosser une image de cette interaction et de son évolution. J'ai tout d'abord établi les relations phylogénétiques entre les espèces de Lymnaeidae, puis retracé l'évolution de différents caractères, tels que la susceptibilité à l'infestation par Fasciola hepatica et F. gigantica. Alors que F. hepatica est un parasite généraliste, capable d'infester des mollusques de presque tous les clades de la famille Lymnaeidae, l'infestation par F. gigantica est plus restreinte à un clade. J'ai ensuite étudié plus finement la coévolution entre le parasite F. hepatica et deux de ses hôtes Lymnaeidae (Galba truncatula et Omphiscola glabra) au sein d'une métapopulation, ce qui a confirmé la stratégie généraliste de F. hepatica. En plus, il semblerait que les mollusques parasités et non parasités de G. truncatula aient des différences génétiques, au moins dans cinq des huit populations étudiées. J'ai caractérisé la diversité génétique de deux espèces de mollusques envahissantes, préférentiellement autogames et impliquées dans la transmission de F. hepatica : Pseudosuccinea columella et Lymnaea sp. On trouve une diversité génétique très réduite, chez ces deux espèces, ce qui pourrait faciliter leur expansion géographique et leur infestation par F. hepatica. Ce travail m'a ensuite conduit à mesurer le temps d'attente avant l'autofécondation et la dépression de consanguinité chez ces deux espèces. J'ai trouvé que ces deux espèces sont caractérisées par une dépression de consanguinité très faible et un temps d'attente nul, ce qui confirme les résultats obtenus lors d'une collaboration dans une étude à plus large échelle. Cette thèse souligne l'importance des études en évolution pour comprendre l'épidémiologie des maladies parasitairesParasites constitute a selective pressure to almost all living beings. This thesis addresses the host-parasite interaction in the Lymnaeidae (Gastropoda) Fasciolidae (Trematoda; liver flukes) system through different approaches, with the aim to give a comprehensive image of this interaction and its evolution. First, I established the phylogenetic relationships among Lymnaeidae species, and then mapped the evolution of different characters such as the susceptibility to the infection by Fasciola hepatica and F. gigantica. While F. hepatica is a generalist parasite, capable to infect snails from almost all clades of the Lymnaeidae, infection by F. gigantica is restricted to one clade. Next, I studied the co-evolution between the parasite F. hepatica and two of its intermediate host species (Galba truncatula and Omphiscola glabra) at a finer scale: within a metapopulation. This study confirmed the generalist strategy of F. hepatica. In addition, it seems that parasitized and non-parasitized G. truncatula snails exhibit genetic differences, at least in five out of eight studied populations.I also characterized the genetic diversity of two species of invasive snails involved in the transmission of F. hepatica: Pseudosuccinea columella and Lymnaea sp. We discuss the possible reasons of invasion success in these snails, despite their low genetic diversity, which could facilitate their infection by F. hepatica. Their capacity to respond to parasitism is certainly reduced, all the more that these species are preferential selfers. This work has then led me to measure the waiting time before self-fertilization and inbreeding depression in these two snails. I found that these two species are characterized by low inbreeding depression and present no waiting time, which confirms the results obtained in a collaborative project at larger phylogenetic scale. This thesis strengthens the importance of evolutionary studies to understand the epidemiology of parasitic diseases
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Suwan, Narissara. "Analysis of salivary gland proteins in the mosquito Anopheles stephensi." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343680.
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Ramly, Nur Zazarina. "Molecular analysis on the superfamily of surface antigens from the apicomplexan parasite Eimeria tenella." Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.577790.
Full textAbstract:
The work in this thesis has been involved with molecular and structural analysis on the superfamily of surface antigens from the apicomplexan parasite Eimeria ten ella, which causes coccidiosis in chickens. Infection by Eimeria is thought to involve a role for a superfamily of more than 60 cysteine-rich surface antigens (SAGs) in host-parasite interactions. These cysteine-rich SAGs can be divided into two families each with two clusters (A and Bf C and D) within which considerable sequence similarity can be seen. A representative member of the family, SAG 19 (cluster A), has been over-expressed in E. coli, purified and crystallised by the hanging-drop method of vapour diffusion using ammonium sulphate as the precipitant. Crystals of SAG 19 diffract to beyond 1.32 A resolution and belong to space group 14 with unit cell dimensions a = b = 108.1 A, c = 37.42 A with a single subunit in the asymmetric unit.
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Odoemelam, Edwin Chukwuemeka. "Genomic analysis of the fresh water mollusc Biomphalaria glabrata to understand host : parasite interactions." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4431.
Full textAbstract:
The fresh water mollusc Biomphalaria glabrata is the intermediate host for the trematode parasite Schistosoma mansoni, this parasite is responsible for the human disease Schistosomiasis. The significance of B. glabrata in the transmission of schistosomiasis is such that it has been selected for complete genome sequencing. The Biomphalaria glabrata embryonic cell line is an important resource for researchers investigating the interaction between the snail and parasite. The genome of the Bge cells was analysed at the chromosomal level, using DAPI karyotyping. The karyotype revealed extensive aneuploidy, whereby a modal chromosome complement of 63 and 67 was observed in two isolates of the Bge cells, which exceeds B. glabrata’s 2n=36 chromosome number. Indeed, in addition to characterising the Bge cell chromosomes, a method was established for mapping single copy B. glabrata genes onto the chromosomes from the Bge cells using fluorescence in situ hybridisation. Despite the Bge cell’s inherent aneuploidy, the four genes mapped onto diploid homologous chromosomes. This methodology will be an important resource for the genome sequencing consortium. The interphase nucleus is an organised organelle, whereby chromosomes and gene loci have been shown to be located non-randomly and hence it is hypothesised that the organisation of the interphase nucleus is pertinent to the function of the genome. Since there is no data on how the genes of the snail genome behaves in interphase, it was assessed in the Bge cells line. Again, this is important for the sequencing initiative, but also for evolutionary biology. Radially distributed chromosome territories were observed in the nuclei of the Bge cells. The territory position was organised according to territory size, with small chromosome territories positioned towards the interior and large territories intermediately located. In addition, four B. glabrata genes were positioned non-randomly in the interphase nuclei of the Bge cells, again emphasising organised positioning of the genome. With co-culture of S. mansoni miracidia with the Bge cells there is up regulation of specific genes known to be involved in the host response to parasite. These genes are dramatically relocated within the interphase nuclei, implying that these are specific parasite induced nuclear events. An analysis of the genomic distribution of specific histone modified chromatin in the interphase nuclei of B. glabrata, revealed different nuclear distribution of modified chromatin. Indeed, a statistically significant difference in these patterns was observed between juvenile and adult snails, indicating developmental differences in the organisation of the snails’ genome. These differences maybe relevant to the snails’ resistance/susceptibility to the parasite.
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DeConti, Derrick K. "Systematic Analysis of Duplications and Deletions in the Malaria Parasite P. falciparum: A Dissertation." eScholarship@UMMS, 2004. http://escholarship.umassmed.edu/gsbs_diss/869.
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Duplications and deletions are a major source of genomic variation. Duplications, specifically, have a significant impact on gene genesis and dosage, and the malaria parasite P. falciparum has developed resistance to a growing number of anti-malarial drugs via gene duplication. It also contains highly duplicated families of antigenically variable allelic genes. While specific genes and families have been studied, a comprehensive analysis of duplications and deletions within the reference genome and population has not been performed. We analyzed the extent of segmental duplications (SD) in the reference genome for P. falciparum, primarily by a whole genome self alignment. We discovered that while 5% of the genome identified as SD, the distribution within the genome was partition clustered, with the vast majority localized to the subtelomeres. Within the SDs, we found an overrepresentation of genes encoding antigenically diverse proteins exposed to the extracellular membrane, specifically the var, rifin, and stevor gene families. To examine variation of duplications and deletions within the parasite populations, we designed a novel computational methodology to identify copy number variants (CNVs) from high throughput sequencing, using a read depth based approach refined with discordant read pairs. After validating the program against in vitro lab cultures, we analyzed isolates from Senegal for initial tests into clinical isolates. We then expanded our search to a global sample of 610 strains from Africa and South East Asia, identifying 68 CNV regions. Geographically, genic CNV were found on average in less than 10% of the population, indicating that CNV are rare. However, CNVs at high frequency were almost exclusively duplications associated with known drug resistant CNVs. We also identified the novel biallelic duplication of the crt gene – containing both the chloroquine resistant and sensitive allele. The synthesis of our SD and CNV analysis indicates a CNV conservative P. falciparum genome except where drug and human immune pressure select for gene duplication.
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DeConti, Derrick K. "Systematic Analysis of Duplications and Deletions in the Malaria Parasite P. falciparum: A Dissertation." eScholarship@UMMS, 2015. https://escholarship.umassmed.edu/gsbs_diss/869.
Full textAbstract:
Duplications and deletions are a major source of genomic variation. Duplications, specifically, have a significant impact on gene genesis and dosage, and the malaria parasite P. falciparum has developed resistance to a growing number of anti-malarial drugs via gene duplication. It also contains highly duplicated families of antigenically variable allelic genes. While specific genes and families have been studied, a comprehensive analysis of duplications and deletions within the reference genome and population has not been performed. We analyzed the extent of segmental duplications (SD) in the reference genome for P. falciparum, primarily by a whole genome self alignment. We discovered that while 5% of the genome identified as SD, the distribution within the genome was partition clustered, with the vast majority localized to the subtelomeres. Within the SDs, we found an overrepresentation of genes encoding antigenically diverse proteins exposed to the extracellular membrane, specifically the var, rifin, and stevor gene families. To examine variation of duplications and deletions within the parasite populations, we designed a novel computational methodology to identify copy number variants (CNVs) from high throughput sequencing, using a read depth based approach refined with discordant read pairs. After validating the program against in vitro lab cultures, we analyzed isolates from Senegal for initial tests into clinical isolates. We then expanded our search to a global sample of 610 strains from Africa and South East Asia, identifying 68 CNV regions. Geographically, genic CNV were found on average in less than 10% of the population, indicating that CNV are rare. However, CNVs at high frequency were almost exclusively duplications associated with known drug resistant CNVs. We also identified the novel biallelic duplication of the crt gene – containing both the chloroquine resistant and sensitive allele. The synthesis of our SD and CNV analysis indicates a CNV conservative P. falciparum genome except where drug and human immune pressure select for gene duplication.
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Epping, Kerstin [Verfasser], and Klaus [Akademischer Betreuer] Brehm. "Molekulare Analyse der hormonellen Wirt-Parasit Kreuzinteraktion über TGF-β-Zytokine bei der Alveolären Echinokokkose / Kerstin Epping. Betreuer: Klaus Brehm." Würzburg : Universitätsbibliothek der Universität Würzburg, 2011. http://d-nb.info/101592512X/34.
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Aul, Elsa [Verfasser], and Iris [Akademischer Betreuer] Bruchhaus. "Genomweite Sequenzierung des Fledermaus-Malariaparasiten Polychromophilus murinus und bioinformatische Analyse von Parasit-Wirt-Interaktions-Proteinen / Elsa Aul ; Betreuer: Iris Bruchhaus." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1214370535/34.
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BOMFIM, Tatiane Cristina dos Santos. "Avalia??o do perfil glic?dico e da biologia reprodutiva de Biomphalaria glabrata (Mollusca) experimentalmente co-infectada por Angiostrongylus cantonensis (Nematoda) e Echinostoma paraensei (Trematoda)." Universidade Federal Rural do Rio de Janeiro, 2016. https://tede.ufrrj.br/jspui/handle/jspui/1571.
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The interaction between intermediate hosts and helminths can cause metabolic and reproductive changes in the host snail, they start using their reserves to maintain its vital functions, immune system activation, repair of tissue damage and also to supply the necessary energy for the parasites development. Investigations of co-infection by different helminths can provide essential information about the biology of their co-existence. Our aims are investigate the reproductive changes, evaluate the activity of lactate dehydrogenase and the concentrations of glucose in the hemolymph and glycogen in the digestive gland complex and cephalopedal mass, and also verify histological and histochemical changes of Biomphalaria glabrata experimentally co-infected with Echinostoma paraensei and Angiostrongylus cantonensis. Five groups of snails i.e. uninfected, with single and double infections, either E. paraensei first (E+A) or A. cantonensis first (A+E) were followed; three times a week during four weeks the numbers of egg masses, eggs and hatched snails were counted. Histological and histochemical samples of the ovotestis, albumen gland, digestive gland complex and cephalopedal mass were collected after four weeks as well samples for the biochemical analysis. The number of egg masses/snail, eggs/snail and hatched snails showed significant differences comparing the control group to all infected groups, especially in group E + A, with the majority of values of parameters analyzed lower than 50% of those observed for control snails. A significant decrease in glucose levels and glycogen content, in contrast an increase of lactate dehydrogenase activity was observed in the infected snails. These results indicate intense energy demand that takes the snail increasing the anaerobic degradation of carbohydrates in the infected snails to obtain energy in an attempt to maintain homeostasis. The histological analysis showed that presence of both parasites in the all organs analyzed and the parasites were associated with cell disorganization.
A intera??o entre hospedeiros intermedi?rios e helmintos pode causar altera??es metab?licas e reprodutivas no molusco hospedeiro, que come?am a usar suas reservas para manter as fun??es vitais, na elabora??o de resposta imunol?gica e repara??o de danos teciduais e tamb?m para compensar a drenagem de nutrientes/energia pelos parasitos em desenvolvimento. Investiga??es sobre as co-infec??es por helmintos de esp?cies diferentes podem fornecer informa??es essenciais sobre a biologia da sua co-exist?ncia, refletindo aspectos mais pr?ximos ?queles que encontramos em condi??es naturais. Nossos objetivos foram investigar as altera??es reprodutivas, avaliar a atividade da lactato desidrogenase e as concentra??es de glicose na hemolinfa e glicog?nio no complexo gl?ndula digestiva-g?nada e massa cefalopediosa, e tamb?m verificar altera??es histol?gicas e histoqu?micas de Biomphalaria glabrata experimentalmente co-infectados com Echinostoma paraensei e Angiostrongylus cantonensis. Cinco grupos de moluscos (n?o infectados, com infec??es simples (Echinostoma paraensei ou Angiostrongylus cantonensis) e dupla, seja E. paraensei primeiro (E + A) ou A. cantonensis primeiro (A + E)) foram acompanhados; tr?s vezes por semana durante quatro semanas o n?mero de massas de ovos, n?mero de ovos e n?mero de moluscos eclodidos foram contados. Amostras para a an?lise histol?gica e histoqu?mica do ovoteste, gl?ndula do alb?men, complexo gl?ndula digestiva e massa cefalopediosa foram coletadas ap?s quatro semanas, assim como amostras para a an?lise bioqu?mica. O n?mero de massas de ovos/molusco, ovos/molusco e moluscos eclodidos dos moluscos infectados apresentaram diferen?as significativas quando comparados com o grupo controle, especialmente no grupo E + A, cuja a maioria dos valores dos par?metros analisados foi inferior a 50% dos valores observados para os moluscos controle. Um decr?scimo significativo nos n?veis de glicose e de glicog?nio, em contraste com um aumento de atividade da lactato desidrogenase foi observado nos exemplares infectados. Estes resultados indicam que a demanda de energia intensa leva o molusco infectado ao aumento da degrada??o anaer?bia de carboidratos para obten??o de energia buscando atender ao aumento da demanda energ?tica, numa tentativa de manter a homeostase glic?mica, por?m redu??es significativas s?o observadas. As an?lises histol?gicas e histoqu?micas mostraram a presen?a de ambos os parasitos nos ?rg?os analisados associados com intensa desorganiza??o celular.
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Wiese, Anna Johanna. "Comparative analyses of primary carbon metabolism in parasitic plant species." Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85740.
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Thesis (MSc)--Stellenbosch University, 2013.ENGLISH ABSTRACT: Most terrestrial plants make use of beneficial symbiotic associations to obtain nutrients (eg. nitrogen (N) and phosphorous (P)) from fungi in exchange for photoautotrophic carbon. However, plant parasitism (defined here as the ability of certain plants to parasitize other living material) has evolved in the plant kingdom and such plants obtain some, or all, of their nutritional needs from a host, which is severely negatively impacted by the parasite. While the physiological adaptations are well studied, the underlying molecular and biochemical mechanisms of plant parasitism remain largely unknown. As a first approach, a biochemical blueprint of primary metabolites present within parasitic plant species was constructed. The metabolomes of nineteen parasitic plants, ranging from hemi- and holoparasitism to mycoheterotrophism, were profiled via gas chromatography mass spectrometry (GC MS) based technology and targeted spectrophotometric assays. Based on these analyses, three important observations were made. First, parasitic plants were severely carbon deprived, despite being successful in colonizing and exploiting their hosts. Second, the levels of organic acids participating in mitochondrial respiration decreased and certain amino acids and soluble protein content increased. This suggests that parasitic plants utilize alternative respiratory substrates to compensate for a limitation in carbon supply. Third, although characterized by reduced carbohydrate pools, minor sugars normally not associated with plant metabolism, dominated the soluble sugar pool. The presence and significance of one of these sugars, namely turanose (α-D-glucopyranosyl-(1→3)-α-D-fructofuranose), was further investigated. Turanose biosynthetic reactions could be demonstrated in Orobanche minor extracts. Protein purification and mass spectrometry identification suggested that turanose biosynthesis occurred uniquely in parasitic plants. Future work will elucidate the functional significance of turanose metabolism in plant parasitism. Taken together, this study significantly contributes to our understanding of plant parasitism through development of metabolic signatures associated with distinct parasitic classes. These biochemical profiles highlighted several important strategies and alternative metabolic pathways that are either expressed or constitutively activated during parasitism. This knowledge broadens the scope of using parasitic plants in several biotechnological applications or as a novel research tool to address fundamental questions in plant science.
AFRIKAANSE OPSOMMING: Meeste landelike plante maak gebruik van voordelige simbiotiese assosiasies met swamme om voedinsgtowwe (bv. stikstof (N) en fosfor (P)) van hulle te verkry in ruil vir koolstof geproduseer deur die plant. Plant parasitisme (gedefinieer hier as die vermoë van sekere plante om ander lewende materiaal te parasiteer) het ontwikkel in die planteryk waar hulle sommige, of al hul voedings stowwe van 'n gasheer plant ontvang, wat erg negatief geraak word deur die parasiet. Terwyl die fisiologiese aanpassings goed gebestudeer is, is die onderliggende molekulêre en biochemiese meganismes van plant parasitisme steeds grootliks onbekend. As 'n eerste benadering, was hierdie projek geïnisieer om 'n biochemiese bloudruk op te bou van primêre metaboliete teenwoordig in parasitiese plante. Die metabolome van negentien parasitiese spesies, wat wissel van hemi - en holoparasiete tot mikoheterotrofiese plante, is ondersoek deur gas chromatografie – massa spektrometrie (GC MS) gebaseerde tegnologie en geteikende spektrofotometriese toetse. Gebaseer op hierdie ontledings was drie belangrike waarnemings gemaak. Eerstens, parasitiese plante was erg koolstof arm, ten spyte daarvan dat hulle suksesvol is in die aanhegting en ontginning van voedingstowwe vanaf gasheer plante. Tweedens, die vlakke van organiese sure wat deelneem aan mitochondriale respirasie het afgeneem, terwyl sekere aminosure en oplosbare proteïen inhoude toegeneem het. Dit dui daarop dat parasitiese plante gebruik maak van alternatiewe respiratoriese substrate om te vergoed vir 'n beperking in koolstof aanbod. Derde, alhoewel parasitiese plante gekenmerk word deur verminderde koolhidraat inhoude, het skaarse suikers wat normaalweg nie verband hou met plant metabolisme nie, hulle oplosbare suiker inhoud oorheers. Die teenwoordigheid en betekenis van een van hierdie suikers, naamlik turanose (α -D -glucopyranosyl-(1→3)-α-D-fructofuranose), was verder ondersoek. Die sintese reaksie van turanose kan gedemonstreer word in Orobanche hederae uittreksels. Proteïen suiwering en massa spektrometrie identifikasie het voorgestel dat turanose biosintese uniek plaasvind in parasitiese plante. Toekomstige werk sal aandui wat die betekenis is van turanose metabolisme in plant parasitisme. Saamgevat het hierdie studie aansienlik bygedra tot ons begrip van plant parasitisme deur ontwikkeling van metaboliese handtekeninge wat verband hou met onderskeie parasitiese klasse. Hierdie biochemiese profiele beklemtoon verskeie belangrike strategieë en alternatiewe metaboliese paaie wat óf uitgedruk of konstitutief geaktiveer word tydens parasitisme. Hierdie kennis verbreed die omvang van die gebruik van parasitiese plante in verskeie biotegnologiese toepassings of as 'n nuwe navorsings instrument om fundamentele vrae in plant wetenskap aan te spreek.
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Samarasinghe, Buddhini. "Analysis of RNA interference in the parasitic nematode Haemonchus contortus." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1957/.
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Parasitic nematode infections worldwide cause a significant impact on human health, as well as economic and welfare losses to the animal and agriculture industries. The principal method of control for parasitic nematode infections is currently limited to repeated treatments with anthelmintic drugs, but widespread resistance to all major classes of these drugs is a growing problem. As a result, there is an urgent need for alternative methods of controlling these infections, and the development of molecular vaccines and novel drugs represent two possible approaches. However, both these approaches require a deeper understanding of gene function in order to identify suitable control targets. This project examines RNA interference (RNAi) in the parasitic nematode Haemonchus contortus to determine if this could be developed as a functional tool and advance the discovery of novel control targets for parasitic nematodes. RNAi has proven less effective in parasitic nematodes than in the free-living model nematode Caenorhabditis elegans and it is unclear why this is so. This project examined the reliability of RNAi in H. contortus, and several genes were successfully silenced using RNAi. Further analysis of RNAi susceptible genes revealed that RNAi silencing appears to be related to the site of expression of the target gene; genes expressed in tissues which are accessible to the environment such as intestine, excretory cell and amphids were silenced by RNAi. Upstream promoter regions of RNAi susceptible genes were examined for the presence of motifs which may regulate spatial gene expression, an approach that could be used to predict gene susceptibility to RNAi. RNAi treated larvae were subsequently used to infect sheep in the first in vivo RNAi study, resulting in a significant impact on worm survival in vivo. In addition, several components of the RNAi pathway in H. contortus were characterised in this project, demonstrating the presence of a functional RNAi pathway that is capable of reliably silencing genes. In conclusion, the findings presented in this project suggest that RNAi may be used in the future to evaluate the function of a novel vaccine or drug target for controlling H. contortus infections in sheep.
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Hiestand, Shelby Jane. "ASSESSMENT AND SPATIAL ANALYSIS OF BOBCAT PARASITES IN SOUTHERN ILLINOIS." OpenSIUC, 2013. https://opensiuc.lib.siu.edu/theses/1285.
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Bobcats (Lynx rufus) are the most abundant and widely-distributed wild felid species in North America. The current increase of population densities of bobcats raises concerns about their importance as reservoirs of pathogens and parasites that may affect the wildlife community. Although many parasites found in bobcats also infect other wild and domestic animals, knowledge of bobcat parasites and potential impacts on other species has received relatively little attention. My objectives were to determine the endoparasite species present in Illinois bobcats, compare them to previous records in the United States, and predict their potential presence in southern Illinois using the program MAXENT. To complete these goals, necropsies were performed on 67 road-killed or trapped bobcats collected during 2003-12. I found infections caused by cestodes, nematodes, and trematodes including Taenia rileyi (70.1%), Toxocara cati (25.3%), and Alaria marcianae (41.7%). The highest mean abundance was found for Alaria marcianae (81) followed by Taenia rileyi (4) and Toxocara cati (3). Alaria marcianae had the highest intensity (193) with a range of 1-2,872. The comparison of parasite communities across 10 geographic locations using Jaccard's similarity index showed low similarity among all regions with the most similar community between Nebraska and Texas (0.53) and Arkansas being the most similar to southern Illinois (0.74). Parasite presence data were then used with environmental data layers of water, soil, land cover, human density, and climate variables in MAXENT to create maps of potential presence of 3 parasite species in a 46,436-km2 portion of southern Illinois. Precipitation of seasonality, the change of average rainfall seasonally, and average precipitation were the highest contributing variables used by MAXENT when creating probability maps of Taenia rileyi (55.1%) and Alaria marcianae (58.4%). For Toxocara cati land cover (40.6%) and soil (27.6%) were the highest contributing variables. With the addition of a sampling bias layer (i.e., bobcat presence) all climatic variables were low contributors (0.0-2.0%) while land cover remained important for Alaria marcianae (7.6%) and Toxocara cati (6.3%); human density (4.8%) was of secondary importance for Taenia rileyi after including the bias layer. Variables of importance likely represent habitat requirements necessary for the completion of parasite life cycles. Larger areas of potential presence were found for generalist parasites such as Taenia rileyi (85%) while potential presence was less likely for parasites with complex life cycles such as Alaria marcianae (73%). My study provides information to wildlife biologists and health officials regarding the potential impacts of growing bobcat populations in combination with complex and changing environmental factors.
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Wolowczuk, Isabelle. "Détermination et analyse des épitopes T fonctionnels de l'antigène protecteur Sm28GST du parasite trématode schistosoma mansoni." Lille 1, 1991. http://www.theses.fr/1991LIL10032.
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L'antigène de 28 kiloDalton du parasite trématode Schistosoma mansoni : Sm28GST, a été préalablement démontré comme pouvant induire des niveaux de protection très élevés dans différents modèles animaux : rongeurs et primates. L'analyse de la séquence primaire de la molécule Sm28GST, a conduit à la synthèse de sept peptides qui ont été utilisés pour identifier les épitopes T et B majeurs de la molécule vaccinante. Deux d'entre ces peptides (le 24-43 et le 115-131) contiennent des déterminants T majeurs de Sm28GST. Les peptides 24-43 et 115-131 induisent la prolifération in vitro de lymphocytes T de rat et de souris immunisés par Sm28GST native et recombinante. Le peptide 24-43 contient un épitope T « helper » d'une réponse IgE. Une construction multi-épitopique comprenant 8 copies du peptide 115-131 (dénommee « octopus »), est immunogène et antigénique dans trois modèles animaux différents: le rat, la souris et le babouin. Des rats immunisés par l'octopus sont protégés d'une infection ultérieure par le parasite. Ces peptides sont exposés par le système immunitaire durant l'infection de rats, souris et de babouins
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CITARD, THIERRY. "Analyse de la diversite genetique des isolats et identification d'antigenes recombinants du parasite hematozoaire babesia canis." Paris 6, 1996. http://www.theses.fr/1996PA066832.
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La diversite genetique de l'espece babesia canis, parasite intra-erythrocytaire du chien, a ete sondee par la technique des empreintes genetiques, en analysant le polymorphisme de longueur des fragments de restriction de l'adn genomique. La sonde ps8, d'une taille de 1,2 kilopaires de bases et qui detecter specifiquement jusqu'a 20 picogrammes d'adn de b. Canis, a permis de reveler une large diversite genetique entre les nombreux isolats parasitaires recoltes en france. De plus, plusieurs sous-populations, selectionnees in vitro a partir d'un isolat unique et presumees clonales, ont pu etre identifiees egalement par leur empreinte genetique. Les resultats ont montre que l'empreinte genetique d'un isolat donne apparait comme la superposition des empreintes genetiques des clones, notamment des clones quantitativement majoritaires dans l'isolat. L'analyse du parasite b. Canis a ete etendue a l'identification et a la caracterisation de plusieurs de ses antigenes. Une banque genomique d'expression a ete criblee avec des serums hyper-immuns, collectes chez des chiens proteges cliniquement contre la babesiose. Cent trente six clones recombinants exprimant des fragments d'antigenes de b. Canis ont ete identifies. L'etude des reactions serologiques croisees a permis de classer quatre vingt dix clones en onze familles et cinq super-familles distinctes, simplifiant ainsi l'analyse. Des antiserums monospecifiques et polyclonaux diriges contre l'antigene recombinant ra7, de 87 kilodaltons, ont ete obtenus chez des souris et un chien. Les anticorps de souris et de chien anti-ra7 reagissent specifiquement, a la fois, avec majoritairement trois proteines parasitaires de 120/115 et 105 kilodaltons, et avec les deux extremites polaires des merozoites, et majoritairement avec l'extremite apicale.
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Paris, Laurianne. "Analyse des interactions entre le parasite Nosema ceranae et l'insecticide fipronil chez l'abeille domestique Apis mellifera." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC062/document.
Full textAbstract:
De nombreuses études suggèrent que le déclin des colonies d’abeilles domestiques (Apis mellifera) serait dû à l’action combinée de plusieurs facteurs de stress, et notamment des agents pathogènes et des pesticides. Nous avons précédemment démontré qu’une co-exposition des abeilles au parasite intestinal Nosema ceranae et à l'insecticide fipronil, administré chroniquement en doses sublétales, entraînait une forte augmentation de la mortalité des abeilles. De plus, des études suggèrent que l'infection par N. ceranae pourrait augmenter la capacité antioxydante des cellules intestinales de l'abeille. Nous nous sommes demandé si l'élévation du taux de mortalité dans un contexte d'infection, combiné à une intoxication au fipronil, pourrait être le résultat d'une production d'espèces réactives de l'oxygène (ERO). Nos résultats indiquent une diminution de la quantité des ERO, mais aussi de la quantité de protéines oxydées en présence de N. ceranae. Ceci pourrait être la résultante d’une augmentation des activités enzymatiques antioxydantes. Lorsque les abeilles ont été traitées avec les deux facteurs de stress (N. ceranae et fipronil), nous n’avons cependant pas mesuré d’augmentation des ERO, tandis que l’oxydation des protéines était significativement augmentée. Ainsi, la présence du parasite semble perturber la balance oxydative des cellules intestinales et pourrait augmenter la toxicité du fipronil. Des études complémentaires ont également été menées in vitro sur des cellules humaines HFF, infectées avec une autre espèce microsporidienne, Encephalitozoon cuniculi, et/ou exposées au fipronil. Les résultats ont montré que la présence du parasite limitait l’augmentation des ERO induite par le fipronil. De plus, des résultats préliminaires tendent à montrer une augmentation de l’activité métabolique des mitochondries dans les cellules infectées par le parasite. Enfin, dans le but de mieux comprendre le dialogue N. ceranae/abeille/microbiote intestinal, nous avons analysé par une approche de séquençage d’amplicons d’ADNr et d’ARNr 16S la composition et l’abondance des communautés microbiennes de l’intestin après infection et/ou intoxication chronique avec différents pesticides. N. ceranae semble perturber l’activité de plusieurs groupes bactériens, et la présence de pesticides accroît fortement ces perturbations. Ainsi, l’impact d’une co-exposition N. ceranae/pesticides sur le microbiote intestinal pourrait être l’un des éléments clés du déclin des coloniesMany studies suggest that the observed decline of Apis mellifera honeybee colonies would be due to the combined action of multiple stressors, including both pathogens and pesticides. We previously demonstrated that the honeybee co-exposure to the gut parasite Nosema ceranae and the fipronil insecticide, administered chronically in sublethal doses, highly increased the bee mortality. Moreover, studies suggest that the infection by N. ceranae may increase the antioxidant capacity of the bee intestinal cells. We wondered whether the increase in mortality rate when infection is combined with fipronil intoxication could be the result of reactive oxygen species (ROS) production. Our results indicate that both the ROS amount and the concentration of oxidized proteins decreased upon infection. This could be the result of an increased antioxidant enzymatic activities. When bees were co-exposed to both stressors (N. ceranae and fipronil), we did not measured any increase in ROS level, but the amount of oxidized proteins was significantly increased. Thus, the presence of the parasite seems to disrupt the oxidative balance of the intestinal cells and could increase the toxicity of fipronil. Complementary studies were also conducted in vitro with human cells (HFF), infected with a different microsporidian species, Encephalitozoon cuniculi, and/or treated with fipronil. The results showed that the presence of the parasite reduced the increase in ROS induced by fipronil. In addition, preliminary results showed an increase in mitochondrial metabolic activity in cells infected with the parasite. Finally, in order to better understand the N. ceranae/honeybee/intestinal microbiota dialogue, we analysed the composition and the abundance of microbial communities in the gut after infection and/or intoxication with different pesticides using a next generation sequencing of both rDNA and rRNA 16S amplicons. N. ceranae seems to upset the activity of different groups of bacteria, and the presence of pesticides greatly increased these disturbances. Thus, the impact of N. ceranae/pesticide co-exposure on the intestinal microbiota may be one of the key elements in the decline of honey bee colonies