La maladie d’Alzheimer (MA) se présente souvent comme un déclin progressif des fonctions cognitives et comportementales. Au niveau biologique, on observe une accumulation de la protéine bêta-amyloïde (Aß) et de la protéine tau, une altération de la fonction synaptique ainsi qu’une mort neuronale. Des travaux récents ont démontré qu’une souche spécifique de probiotiques, Lacticaseibacillus rhamnosus HA-114 (HA-114), avait des propriétés neuroprotectrices dans plusieurs modèles de maladies neurodégénératives. Le projet de recherche présent visait à caractériser les aspects neurophysiologiques d’une souche de nématodes transgéniques exprimant l’Aß et valider la neuroprotection de HA-114 dans ce modèle ainsi que dans un modèle murin de la MA (APP/PS1). Les résultats présentés dans ce manuscrit montrent que les vers transgéniques exprimant le fragment 1-42 de l’Aß récapitulent des caractéristiques clés de la MA, soit une altération de la santé neuronale et de la mémoire liée à l’âge. Il s’agit donc d’un nouvel outil pour l’investigation de la physiopathologie de la MA et pour l’essai de molécules ayant un potentiel thérapeutique. Les données expérimentales montrent aussi que l’administration de HA-114 permet d’atténuer les phénotypes de neurodégénérescence et de paralysie liée à l’âge. Cela témoigne d’un potentiel en vue de l’amélioration de la qualité de vie des patients qui souffrent de la MA. L’étude des effets de HA-114 dans un modèle murin pourrait révéler de nouvelles avenues d’investigations pour la physiopathologie de la MA et les mécanismes par lesquels on pourrait un jour la traiter. / Alzheimer’s disease (AD) often presents itself as a progressive decline of behavioral and cognitive functions such as memory impairment. On a biological level, this disease presents extracellular accumulation of amyloid-beta (Aß), intracellular accumulation of tau, alteration of synaptic function and neuronal loss. Recent data showed that a supplementation with a specific probiotic strain of bacteria, Lacticaseibacillus rhamnosus HA-114 (HA-114), had a neuroprotective effect in several neurodegenerative disease models. This project aimed to characterize the neurophysiological aspects of a specific nematode strain expressing the Aß1-42 fragment and to validate the neuroprotective effect of HA-114 in this nematode strain as well as in the APP/PS1 murin model of AD. Following biochemical and behavioral experiments, data showed that this strain recapitulates key traits of AD: an age-dependent alteration of neuronal health and memory impairment. It was also observed that administrating HA-114 probiotic strain could attenuate age-related phenotypes of neurodegeneration and paralysis. This transgenic strain is therefore a new tool for drug screening and investigating AD’s pathogenesis. The neuroprotective effect of HA-114 observed in this strain shows potential towards an amelioration of the patient’s quality of life. Studying the effects of HA-114 in a murin model could reveal new investigation opportunities for AD’s pathogenesis and mechanisms that could one day cure this disease.

No description available.

Wir fanden konservierte molekulare Signaturen der Regulation durch Δ7-DA und Ascarosid bei Dauer- und infektiösen Larven. Danach wurde die hohe Konservierung durch unsere Analyse in Dauer- und Postdauer-Stadium zwischen den zwei nah verwandten freilebenden Arten C. elegans und C. briggsae identifiziert. Das heißt, dass die relative Veränderung auf mRNA- oder Protein- Ebene zwischen zwei Arten stark korreliert ist. Aber die relative Veränderung innerhalb derselben Art zeigt keine hochgradige Korrelation zwischen mRNA- und Protein-Ebene. Unsere Ergebnisse zeigen in C. elegans Dauerlarven die signifikante Reduzierung der RNA-Mengen in 20 Stoffwechselwegen. Im Gegensatz dazu speicherten Dauerlarven reichlich RNA-Mengen in GO Termen wie Ribosome und Aminoacyl-tRNA biosynthesis. Auf Protein-Ebene sind die Stoffwechselwege von Proteinsynthese und Proteinverarbeitung im endoplasmatischen Retikulum in Dauerlarven herunterreguliert und GO Terme wie Lysosome sind hochreguliert. Durch die Zeitreihenanalyse der Proteom-Remodellierung der molekularen Signaturen beim Austritt aus dem Dauer-Stadium fand wir, dass GO Terme wie metal ion binding signifikant herunterreguliert sind und der Proteinabbau hochreguliert ist. Unsere Ergebnisse vom pSILAC Experiment deuten an, dass die Proteine für Energieerzeugung und Chaperone/Proteinfaltung beim Daueraustritt schnell verbraucht sind und wieder hergestellt werden. Zum Schluss haben wir als Erste den popomR-Assay in C. elegans etabliert und ein Screening der vermeintlichen Proteinbindestellen auf poly-A-RNA durchgeführt, um in der Zukunft die konservierten Mechanismen der post-transkriptionellen Regulation durch RBPs im Dauer-Stadium zu analysieren. / We found the conservation of molecular signatures by regulating with Δ7-DA and Ascarosid in dauer larvae and infective larvae. Then by our comparative analysis, the high degree of conservation between two closely related free-living species C. elegans and C. briggsae was identified in dauer and post-dauer stages. This means that the relative changes are strongly correlated on the mRNA or the protein level between two species. But the relative changes in the same species don’t show any strong correlation between the mRNA and the protein levels. Our results showed a significantly reduced amount of RNA in 20 metabolic pathways in C. elegans dauer larvae. In contrast, dauer larvae stored a large amount of RNA in GO terms such as ribosome and aminoacyl-tRNA biosynthesis. On the protein level, the metabolic pathways of protein synthesis and protein processing in endoplasmic reticulum were downregulated in dauer larvae and the term of lysosome was up-regulated. Due to time course analysis for proteome remodeling of molecular signatures during exit process from dauer stage, we found that GO terms such as metal ion binding were significantly downregulated during dauer exit and at the same time the protein degradation was up-regulated. Our results of pSILAC experiment suggest that the proteins for energy generation and chaperone/protein folding are quickly spent and rebuilded during dauer exit. Finally, we were the first to establish the popomR assay in C. elegans and performed a screening of the putative protein binding sites on poly-A RNA to analyze the conserved mechanisms of post-transcriptional regulation by RBPs in dauer larvae in the future.

Soil is an important ecosystem that supports a wide variety of organisms such as bacteria, fungi, arthropods and nematodes. This sensitive ecosystem may be influenced by various factors, including agricultural management practices. With the introduction of genetically modified (GM) glyphosate-tolerant (RoundUp ® Ready: RR) crops, herbicides such as glyphosate have been increasingly used. However, little is known about the effect of glyphosate on the biological communities in these herbicide-sprayed soils. With the intimate proximity that microorganisms and nematodes have with the roots of plants, these organisms can be used to assess changes that may occur in the soil surrounding roots of RR crops. The aim of this study was to determine microbial community structure and nematode diversity, with emphasis on that of non-parasitic nematodes, in soil samples from conventional soybean (CS) - and RR- soybean fields compared to that in adjacent natural veld (NV) areas. Samples were collected from twenty three sites at six localities that are situated within the soybean-production areas of South Africa. These sites represented fields where RR and CS soybean grew, as well as surrounding NV. All RR fields have been treated with glyphosate for no less than five years. Microbial community structures of the twenty three sites in the RR, CS and NV ecosystems were determined by phospholipid fatty acid (PLFA) analyses. Nematode diversity was determined by extracting the nematodes from soil samples and conducting a faunal analysis. Soil physical and chemical properties were determined by an independent laboratory, Eco-Analytica (North West University, Potchefstroom) according to standard procedures. Results from this study indicated differences in microbial community structure between the various localities. However, there were no significant (p ≤ 0.05) differences in microbial community structures between RR- and CS ecosystems. Soils of both RR- and CS crops were primarily dominated by bacteria. Nematode identification and faunal analysis also indicated no significant (p ≤ 0.05) differences between the different non-parasitic/beneficial nematodes that were present in soils of these two ecosystems during the time of sampling. Non-parasitic nematode communities were primarily dominated by bacterivores. A faunal analysis indicated that most of the sites contained enriched, but unstructured soil food-webs. However, four of the sites showed enriched and structured food webs due to the presence of non-parasitic nematodes with high coloniser-persister (cp) values. Relationships between non-parasitic nematode – and microbial communities showed that there was a positive relationship between nematode functional groups and their corresponding microbial prey. From the results obtained in this study, it can be concluded that the community structures of both non-parasitic nematodes and microorganisms shared similarities. These community structures showed no long-term detrimental effects of glyphosate application in the soils surrounding roots of RR soybean crops. Relationships existed between non-parasitic nematode and microbial communities in the rhizosphere of soybean crops and natural veld. For example, bacterivore nematodes had a strong positive relationship with gram-negative bacteria. Similar but weaker relationships also existed between carnivores, omnivores, plantparasitic nematodes and gram-negative bacteria. A positive relationship also existed between fungivores and fungal fatty acids. This emphasises the value of these organisms as indicators of soil health and also the impact that agricultural practices can have on soils. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Soil is an important ecosystem that supports a wide variety of organisms such as bacteria, fungi, arthropods and nematodes. This sensitive ecosystem may be influenced by various factors, including agricultural management practices. With the introduction of genetically modified (GM) glyphosate-tolerant (RoundUp ® Ready: RR) crops, herbicides such as glyphosate have been increasingly used. However, little is known about the effect of glyphosate on the biological communities in these herbicide-sprayed soils. With the intimate proximity that microorganisms and nematodes have with the roots of plants, these organisms can be used to assess changes that may occur in the soil surrounding roots of RR crops. The aim of this study was to determine microbial community structure and nematode diversity, with emphasis on that of non-parasitic nematodes, in soil samples from conventional soybean (CS) - and RR- soybean fields compared to that in adjacent natural veld (NV) areas. Samples were collected from twenty three sites at six localities that are situated within the soybean-production areas of South Africa. These sites represented fields where RR and CS soybean grew, as well as surrounding NV. All RR fields have been treated with glyphosate for no less than five years. Microbial community structures of the twenty three sites in the RR, CS and NV ecosystems were determined by phospholipid fatty acid (PLFA) analyses. Nematode diversity was determined by extracting the nematodes from soil samples and conducting a faunal analysis. Soil physical and chemical properties were determined by an independent laboratory, Eco-Analytica (North West University, Potchefstroom) according to standard procedures. Results from this study indicated differences in microbial community structure between the various localities. However, there were no significant (p ≤ 0.05) differences in microbial community structures between RR- and CS ecosystems. Soils of both RR- and CS crops were primarily dominated by bacteria. Nematode identification and faunal analysis also indicated no significant (p ≤ 0.05) differences between the different non-parasitic/beneficial nematodes that were present in soils of these two ecosystems during the time of sampling. Non-parasitic nematode communities were primarily dominated by bacterivores. A faunal analysis indicated that most of the sites contained enriched, but unstructured soil food-webs. However, four of the sites showed enriched and structured food webs due to the presence of non-parasitic nematodes with high coloniser-persister (cp) values. Relationships between non-parasitic nematode – and microbial communities showed that there was a positive relationship between nematode functional groups and their corresponding microbial prey. From the results obtained in this study, it can be concluded that the community structures of both non-parasitic nematodes and microorganisms shared similarities. These community structures showed no long-term detrimental effects of glyphosate application in the soils surrounding roots of RR soybean crops. Relationships existed between non-parasitic nematode and microbial communities in the rhizosphere of soybean crops and natural veld. For example, bacterivore nematodes had a strong positive relationship with gram-negative bacteria. Similar but weaker relationships also existed between carnivores, omnivores, plantparasitic nematodes and gram-negative bacteria. A positive relationship also existed between fungivores and fungal fatty acids. This emphasises the value of these organisms as indicators of soil health and also the impact that agricultural practices can have on soils. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Nematode communities in black pepper (Piper nigrum L.) agricultural soil in Thanh An, Binh Phuoc province, were investigated. Soil samples were collected in February 2012 at 9 selected sites belonging to 3 pepper groves. The structure of nematode communities and critical ecological indices were determined to estimate environmental status. 26 genera were found. Of those, plant parasitic nematodes such as Meloidogyne, Helicotylenchus, Hoplolaimus, Psilenchus, and Tylenchidae always appear with high frequency and density, whereas the carnivorous nematodes were rarely detected. The nematode density correlates to the concentration of the total organic matter which correlates closely to the (Ba + Fu) proportion showed by the regression equation y = 0.0223x + 1.6819 with R2 = 1. The ecological triangle model, but not the maturity index (MI), apparently showed the status and processes (decomposition and mineralization) which may be happening in the soils of areas studied. The first grove is rich in nutrient but stressed by chemicals. The second grove is stable, with no chemical stress, but has low nutrient contents. The third grove is affected by chemicals but to a lesser extent than the first one. / Các quần xã tuyến trùng trong hệ sinh thái đất trồng tiêu ở khu vực xã Thanh An, tỉnh Bình Phước được nghiên cứu. Các mẫu đất được thu nhận trong tháng hai năm 2012 tại 9 điểm thuộc 3 vườn tiêu. Cấu trúc quần xã tuyến trùng và các chỉ số sinh thái đã được xác định để qua đó đánh giá trạng thái môi trường. Tổng cộng có 26 giống tuyến trùng được tìm thấy. Trong đó, các loài tuyến trùng ký sinh thực vật như Meloidogyne, Helicotylenchus, Hoplolaimus, Psilenchus, và tuyến trùng ăn nấm Tylenchidae luôn xuất hiện với tần suất và mật độ cao, trong khi tuyến trùng ăn thịt lại hiếm khi được phát hiện. Mật độ tuyến trùng tương quan với lượng chất hữu cơ tổng số mà nó tương quan chặt chẽ với với tỉ lệ nhóm (Ba + Fu) được thể hiện ở phương trình hồi quy là y = 0.0223x + 1.6819 với R2 = 1. Mô hình tam giác sinh thái, nhưng không phải chỉ số tăng trưởng MI, thể hiện rõ trạng thái và các quá trình (sự phân hủy và sự khoáng hóa) có lẽ đang diễn ra trong đất của khu vực được nghiên cứu. Vườn thứ nhất thì giàu dinh dưỡng nhưng bị áp lực bởi hóa chất. Vườn thứ hai khá ổn định, không chịu áp lực hóa chất, nhưng hàm lượng dinh dưỡng rất kém. Vườn thứ ba bị tác động bởi hóa chất nhưng ở mức độ thấp hơn vườn thứ nhất.

Neem cake is a product of the cold pressing from the neem kernels to obtain neem oil. Bio-active substances from neem cake extracted solutions were evaluated for their potential to control the root knot nematodes and other pests of plants. In this study different concentrations of the solution extracted from neem cake was tested against the second stage juveniles of the plant parasitic nematode Meloidogyne spp. and four phytopathogenic fungi: Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytopthora capsici. Toxicity of neem cake extractions is represented by the EC50 value for the second-stage juvenile (J2) of Meloidogyne spp. and the four phytopathogenic fungi via Probit analysis. A 5% dilution of the solvent extracting from neem cake already caused 100% larval mortality after 24 hours exposure. Undiluted neem cake extraction effectively inhibited the growth of the four phytopathogenic fungi. The EC50 value of neem cake on J2-larvae of Meloidogyne nematode and on the fungi Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytophthora capsici was 0.51, 0.74, 0.30, 0.51 and 4.33%, respectively. / Bánh dầu neem là sản phẩm của quá trình ép nhân hạt neem để lấy dầu. Các hoạt chất sinh học từ dịch chiết bánh dầu neem đã được đánh giá có tiềm năng lớn trong phòng trừ tuyến trùng nốt sưng và các loài dịch hại khác của nhiều loại cây trồng. Trong nghiên cứu này các nồng độ dịch chiết khác nhau của bánh dầu neem đã được thử nghiệm khả năng diệt tuyến trùng (ấu trùng tuổi 2 thuộc giống Meloidogyne spp.) và ức chế 4 loài nấm bệnh như: Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. và Phytopthora capsici. Độc tính của dịch chiết bánh dầu neem được biểu diễn bởi giá trị EC50 đối với ấu trùng tuổi 2 của tuyến trùng Meloidogyne spp. và các loài nấm bệnh thông qua phân tích Probit. Dịch chiết bánh dầu neem ở nồng độ 5% đã làm chết 100% cá thể IJ2 của Meloidogyne spp sau 24 giờ phơi nhiễm. Dịch nguyên chất bánh dầu neem ức chế cả 4 loài nấm bệnh. Giá trị EC50 của bánh dầu neem lên ấu trùng tuổi 2 của Meloidogyne spp và các loài nấm bệnh Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytophthora capsici tương ứng là 0.51, 0.74, 0.30, 0.51 và 4.33%.

The melon crop (Cucumis melo L.) is the most exported fruit of Brazil and consist in an important agribusiness to the producers on Northeastern Region of Brazil, having as the main producers the Rio Grande do Norte and Ceará states. Among the limiting factors of this crop, root-knot nematode (Meloidogyne spp.) stand out a major treat, that causes on severed attacked plants malnourishment, poor development of the above-ground portion and shorter root system due to the galls, which is the most characteristic symptom of this disease. With the lack of management tools to the root-knot nematode, alternative measures are needed to avoid losses. In this context, the main objective of the present work was to evaluate the influence of resistance inducers and biological control agents on the control of M. incognita on melon plants, as the influence of these agents on melon plant development and their effects on different M. incognita stages. For these purposes, greenhouse experiments were performed. The first one aimed to verify the host status of melon hybrids to M. incognita and additional three were carried out to verify the influence of resistance inducers and biological control organisms on melon development and on the control of M. incognita on this crop (trials #1, #2 and #3). Also, an additional greenhouse trials were carried out to verify different doses of P. chlamydosporia (Rizotec® ) on the control of M. incognita in melon plants and to verify the potential of culture filtrates (Cf) obtained from biological control organisms on the control of M. incognita and on the melon plant development. In these greenhouse experiments, the reproductive variables final population (Pf), reproduction factor (R value) and nematodes per gram of root (Nem/g) were obtained at the end of the experiments. Additionally, it was evaluated the fresh and dry weight of the aerial portion, the plant height, root weight, fruit weight, stem diameter (measured on stem basis, middle and apex) and chlorophyll content. Additionally, in vitro assays were performed to verify the effect of Cfs on melon seeds and to verify the effect of the Cfs and the partially purified thaxtomin A (PPT) on M. incognita egg hatching. Moreover, three additional assays were carried out to verify the effect of resistance inducers acibenzolar-S-methyl (ASM) and PPT in the penetration and post-penetration of M. incognita second stages juveniles in melon roots. As results, all tested genotypes were susceptible to M. incognita. The Pf values ranged from 2,381.06 to 7,806 nematodes, the R value ranged from 5.95 to 19.5. Also, nem/g values ranged from 271 to 1,791. In trial #1, melon plants treated with resistance inducers presented lower height; despite no statistically differences were found for fresh and dry weight. Also, plants treated with ASM (inoculated and non-inoculated), Paecilomyces lilacinus, (non-inoculated) and Pochonia chlamydosporia (inoculated) produced heavy fruits. On trial #2, all inoculated plants differed statistically on root weight and presented heavier roots than non-inoculated plants, which was due the large amount of galls caused by M. incognita. In addition, treated plants with the biological control agents presented fewer symptoms than control plants. Treated melon plants exhibited higher chlorophyll content on young leaves, when compared with both controls. Moreover, on both treatments the M. incognita population was reduced, except by P. chlamydosporia on the experiment 1. When tested separately, all P. chlamydosporia doses reduced the Pf, however the most efficient were the dose 4 (1g/plant) and dose 5 (2g/plant). Regarding Cf, promising results were obtained. Both Cf from P. lilacinus and Bacillus amyloliquefaciens reduced the M. incognita population, in greenhouse experiment. Additionally, P. lilacinus Cf increased the fruit weight, and B. amyloliquefaciens Cf increased the root weight, despite being inoculated or not. Furthermore, the tested Cfs presented suppressive effect on M. incognita egg hatching, but further evidence is necessary due to lack of statistical differences with the potato-dextrose broth medium (PD). Additionally, the filtrates improved the germination of melon seeds, despite the suppressed effect of PD broth medium on them. Also,i> P. chlamydosporia treatment induced hairy roots, which were not observed on the other treatments. Regarding the penetration assays, juveniles were not observed at 3 days after inoculation (DAI). No effect of ASM in penetration and post-penetration of M. incognita J2 was 13 observed on both experiments. Concerning PPT, penetration was not observed at 3 DAI, but it was observed on the other assessed periods. Furthermore, our data points out that the TPP may speed the nematode cycle on melon roots. In conclusion, the obtained data point out the potential of the resistance inducers, biological control organisms and their culture filtrates on the control of M. incognita on melon plants. / Atualmente, o melão (Cucumis melo L.) consiste na fruta mais exportada do Brasil, consistindo em importante agronegócio para os produtores da região Nordeste do país, tendo como maiores produtores os estados do Ceará e Rio Grande do Norte. Dentre os fatores limitantes para essa cultura, o nematoide das galhas (Meloidogyne spp.) se destaca entre as principais doenças do meloeiro. Plantas sob alta infestação apresentam deficiência nutricional, baixo desenvolvimento da porção aérea e deformação do sistema radicular devido as galhas, que consiste no sintoma mais característico dessa doença. Com a falta de ferramentas de manejo, medidas alternativas são necessárias para evitar maiores perdas. Nesse contexto, o presente trabalho teve por objetivo avaliar a influência de agentes de controle biológico e indutores de resistência no controle de M. incognita em plantas de melão, bem como a influência desses agentes no desenvolvimento do meloeiro em casa de vegetação, além de seus efeitos em diferentes estádios de M. incognita. Dessa forma, experimentos de casa-de-vegetação foram conduzidos, sendo um para verificar a reação de hospedeiro de híbridos de melão à M. incognita, três para verificar a influência de indutores de resistência e agentes de controle biológico no desenvolvimento do meloeiro e no controle de M. incognita (Experimento 1, 2 e 3). Adicionalmente, um experimento foi conduzido para verificar a dose-resposta de Pochonia chlamydosporia (Rizotec®) para controle de M. incognita e dois para verificar o uso potencial de filtrados obtidos a partir de organismos de controle biológico no desenvolvimento do meloeiro e no controle de M. incognita. Nesses experimentos, o fator de reprodução (valor R), população final (Pf) e nematoides por grama de raiz (Nem/g) foram obtidos ao final dos ensaios. Adicionalmente, foram avaliados a massa fresca e seca da parte aérea, altura das plantas, massa das raízes, massa dos frutos por planta, diâmetro do caule (base, meio e ápice) e conteúdo de clorofila. Ademais, realizou-se um experimento para se verificar o efeito de filtrados nas sementes de melão e três para verificar o efeito dos filtrados e da taxtomina parcialmente purificada (TPP) na eclosão dos ovos de M. incognita. Adicionalmente, três experimentos foram realizados para verificar o efeito de indutores de resistência na penetração e desenvolvimento de juvenis J2 de M. incognita nas raízes de meloeiro. Como resultados, todos os genótipos testados foram suscetíveis a M. incognita. A Pf variou de 2.381 à 7.806 nematoides, o valor R variou de 5,7 à 19,5 e o Nem/g foi de 271 à 1.791. No experimento 1, meloeiros tratados com indutores de resistência apresentaram menor altura, embora, nenhuma diferença estatística foi encontrada nas massas frescas e secas das plantas. Adicionalmente, plantas tratadas com acibenzolar-S-metil (ASM) (inoculadas e não inoculadas), P. lilacinus (-N) e P. chlamydosporia (+N) apresentaram frutos mais pesados. Com relação ao experimento 2, todos os tratamentos inoculados apresentaram maior peso das raízes, quando comparada aos tratamentos não inoculados, causado pela deformação da porção radicular. Adicionalmente, plantas tratadas com agentes de controle biológico apresentaram raízes com menos sintomas, quando comparados ao controle. Ademais, plantas tratadas apresentaram maior quantidade de clorofila em folhas jovens, quando comparadas aos controles. Todos os tratamentos, com exceção a P. chlamydosporia no experimento 1, reduziram a população final de M. incognita. Quando testado separadamente, todas as doses de P. chlamydosporia reduziram a Pf de M. incognita, embora as mais eficientes tenham sido a dose 4 (1g/planta) e dose 5 (2g/planta). Com relação aos filtrados, resultados promissores foram obtidos. Os filtrados obtidos a partir de B. amyloliquefaciens e P. lilacinus reduziram as populações finais de M. incognita, embora apenas B. amyloliquefaciens tenha diferido estatisticamente. Adicionalmente, aumento na massa das raízes e na massa dos frutos foram observados para plantas tratadas com filtrados de B. amyloliquefaciens e P. lilacinus, respectivamente. Ademais, todos os filtrados aceleraram a germinação das sementes quando comparado ao meio batata- dextrose, que suprimiu a germinação. Sementes tratadas com o filtrado obtido a partir de P. chlamydosporia apresentaram radículas pilosas, o que não foi observado nos outros tratamentos. Com relação aos experimentos de penetração, juvenis J2 de M. incognita foram observados no interior das raízes em todos os ensaios. Nenhum efeito do ASM foi observado em ambos os experimentos. Com relação a TPP, os dados apontam que o tratamento acelerou o ciclo do nematoide no interior das raízes. Conclui-se, que os dados obtidos apontam para o potencial dos indutores de resistência e agentes de controle biológico e seus filtrados no controle de M. incognita em meloeiro.

Les strongles gastro-intestinaux, dont Haemonchus contortus constituent un problème majeur pour l'élevage des ovins allaitants. Ils entrainent des pertes de production et le recours aux anthelminthiques est remis en question par l'apparition de souches de vers résistantes. La sélection d'ovins plus résistants fait partie des stratégies complémentaires de lutte les plus sérieuses. Cependant sa mise en oeuvre requiert une meilleure compréhension des mécanismes sous-jacents. Cette thèse vise à identifier les régions du génome ovin impliquées dans la résistance aux strongles gastro-intestinaux. Une analyse statistique d'association entre des marqueurs génétiques et des mesures de résistance d'un troupeau d'ovins croisés Martinik Black-belly x Romane a mis en évidence un nombre limité de régions d'intérêt. Parmi celles-ci, un segment du chromosome 12 a été choisi pour effectuer des accouplements raisonnés et valider son rôle dans la résistance à H. contortus. L'effet de cette région a été validé chez les descendants issus d'accouplements assistés par marqueurs génétiques. Cette région semble limiter fertilité des vers femelles tout en contribuant à une réponse immunitaire plus forte. Le rôle d'une région du chromosome 21 dans la variation de concentration plasmatique en pepsinogène, un marqueur de lésions abomasales, a également été confirmé. Un gène candidat sous-jacent est en cours de séquençage et l'analyse des polymorphismes devrait contribuer à la validation de son rôle. Deux autres gènes très proches pourraient également être impliqués et mériteraient une considération future. Ces travaux illustrent à la fois la variation génétique disponible pour les caractères de résistance à H. contortus et la complexité des mécanismes mis en jeu. Des études complémentaires de séquençage et d'étude d'expression par séquençage devrait contribuer à une meilleure compréhension des fonctions des gènes impliqués et de leurs interactions. / Gastro-intestinal nematodes, among which Haemonchus contortus are a major threat to the meat sheep industry. They are responsible for production losses and the apparition of worm populations resistant to drugs limits their use as worm control strategy. Breeding more resistant sheep is among the most practicable alternative strategy. However its implementation requires a deeper understanding of underlying mechanisms. This PhD aims at identifying regions of the ovine genome affecting resistance to gastro-intestinal nematodes. A statistical analysis of existing associations between genetic markers and resistance traits of a Martinik Black-belly x Romane cross-bred sheep flock unraveled a limited number of key players. Among these, a fragment of the chromosome 12 was chosen to perform marker-assisted matings and to validate its role in resistance to H. contortus. The effect of this region was validated in the progenies born from matings. It seems this chromosomic fragment limits female worms fertility and is associated to a stronger immune response. The putative role played by a fragment of the chromosome 21 in plasmatic pepsinogen concentration (a biomarker of abomasal lesions) was also confirmed in this work. A candidate gene underlying this region has been sequenced and the analysis of the detected polymorphisms should confirm its role. Further, two other genes in its vicinity could also play a role in this biological phenomenon and they should also deserve future considerations. This work illustrated both the existing genetic variation for resistance to H. contortus and the associated complexity of underlying mechanisms. Additional sequencing and gene expression sequencing studies should help understanding gene functions and interactions.

Made available in DSpace on 2016-04-28T14:57:35Z (GMT). No. of bitstreams: 1 2008 - Rhadyson Reinaldo Silva do Nascimento.pdf: 1733739 bytes, checksum: b1070eca267f85de92499d2e245add23 (MD5) Previous issue date: 2008-09-03 / Cowpea (Vigna unguiculata L. Walp.) is a very important crop in Brazil, mainly in the north and northeast regions of the country, and is gaining importance in the southeast region. In this crop, nematodes are a great threat, because they can cause yield decrease. Information about these pathogens is very few. In a first approach this work aimed at surveying for the occurrence of plant parasitic nematodes that are associated to cowpea in the State of Rio de Janeiro, through sampling achieved in some locations of Nova Igua?u, Mag?, Serop?dica, S?o Francisco de Itabapoana, and Itagua?, where cowpea is grown cultivated. Eight genera of plant parasitic nematodes we found, besides others, that are free leving that were not identified. At the level of species M. incognita and Rotylenchulus reniformis were identified. Nematode identification was done on the bases of morphometric characteristics descriptive keys M. incognita by juvenile (J2 ) and males characteristics and perineal female patterns and esterases profile. In this step, surveys were carried out aiming at the detection of esterases activity for a population of R. reniformis. Protocols routinely used in isoezymes analysis were tested and showed negative results. On the other hand, assays using PCR tubes with the objective to identify esterase activity demonstrated that it was positive for R. reniformis. Modifications in the common protocols, such as changes in buffer solution at the and steps of the procedures, as well as adjusting pH near to neutrality enabled the establishment of a three band pattern of esterase in the studied populations of R. reniformis. In another phase of this work, six cowpea lines in advanced phase of improvement from determining their behavior when inoculated with M. incognita race 1, M. javanica and R. reniformis. The tomato cv. TRural was used as susceptible pattern. The experiments were carried out under greenhouse condition, using 5,000 eggs + juveniles per experimental plots, as inoculum level; for Meloidogyne species evaluation was done 50 days after nematodes inoculations based in the following parameters: galls indices (IG), egg mass indices (IMO) and reproductions rate (FR), calculated by the relation Pf/Pi ( Pf = final populations and Pi= start population). Among the tested lines, five of then RJ 04-04, RJ 04-08, RJ 04-26, RJ 04-48 and RJ 04-65 showed to be highly resistant and line RJ 04-29 was moderately resistant to M. incognita race 1. In the case of M. javanica all lines were highly susceptible. For evaluation of R. reniformis it was used as inoculum and "pure" population multiplied vegetation home. It was inoculated 5000 eggs and juvenile of males and of immature females. As parameter for evaluation of the resistance of the cowpea lineages to the nematode, the reproduction factor was used (Fr) appraised to the 45 days after inoculation. It was verified that all of the tested lineages were considered susceptible; to cultivate "Costel?o" included as witness showed equal behavior. / O caupi (Vigna unguiculata Walp.) ? uma cultura de grande import?ncia para o pa?s, principalmente na regi?o Norte e Nordeste e vem ganhando espa?o na regi?o Sudeste. Nesta cultura, os nemat?ides possuem influ?ncia significativa, chegando ao ponto de limitar a sua produ??o. As informa??es sobre estes pat?genos no Estado do Rio de Janeiro s?o escassas. Assim, numa primeira etapa, este trabalho teve por objetivo fazer um levantamento de nemat?ides fitoparasitas associados a cultura do caupi no Estado do Rio de Janeiro, por meio de coletas realizadas em alguns munic?pios produtores de caupi cultura. Foram encontrados, um total de oito g?neros de nemat?ides fitoparasitas, al?m de outros de vida livre n?o identificados. Em n?vel de esp?cie foram identificadas Meloidogyne incognita ra?a 2 e Rotylenchulus reniformis. As identifica??es foram efetuadas a partir de caracter?sticas morfom?tricas e aux?lio de chaves descritivas. M. incognita foi identificada pelas caracter?sticas dos juvenis (J2) e de machos, configura??o do modelo perineal das f?meas e perfil de esterases. Foram realizados ensaios com o objetivo de detec??o de atividade de esterase, para uma popula??o do nemat?ide R. reniformis. Para tanto foram testados protocolos rotineiramente usados em an?lises isoenzim?ticas, que apresentaram resultados negativos. Entretanto, ensaios montados em microtubos para PCR, evidenciaram atividade ester?sica para R. reniformis. Finalmente, modifica??es nos protocolos usuais como mudan?as na concentra??o da solu??o tamp?o de revela??o, assim como a fixa??o do pH da mesma pr?ximo a neutralidade, permitiram estabelecer um padr?o com tr?s bandas distintas de esterases na popula??o de R. reniformis estudada. Em uma segunda etapa deste trabalho, seis linhagens de caupi em fase avan?ada de melhoramento para resist?ncia a viroses, foram testadas visando determinar a rea??o das mesmas quando inoculadas com M. incognita ra?a 1, ou M. javanica, ou R. reniformis. A cultivar de tomate TRural foi usada como testemunha suscet?vel nos testes com as duas esp?cies de nemat?ide das galhas radiculares. Os experimentos foram realizados em casa de vegeta??o e usou-se uma carga de in?culo de 5000 ovos + juvenis/repeti??o; para as esp?cies de Meloidogyne a avalia??o ocorreu 50 dias ap?s inocula??o e os par?metros usados foram: ?ndice de galhas (IG), ?ndice de massa de ovos (IMO) e fator de reprodu??o (Fr) calculado pela rela??o Pf/Pi (Pf = popula??o final e Pi = popula??o inicial). Das cinco linhagens testadas, RJ 04-04, RJ 04-08, RJ 04-26, RJ 04-48 e RJ 04-65 comportaram-se como altamente resistentes e a linhagem RJ 04-29 como moderadamente resistente para M. incognita ra?a1. Enquanto que, para M. javanica, todas as linhagem foram altamente suscet?veis. Para avalia??o de R. reniformis foi usado como in?culo uma popula??o pura multiplicada em casa de vegeta??o. Inoculou-se 5000 ovos e/ ou juvenis de machos e de f?meas imaturas. Como par?metro para avalia??o da resist?ncia das linhagens de caupi ao nemat?ide, foi usado o fator de reprodu??o (Fr) avaliado aos 45 dias ap?s inocula??o. Verificou-se que todas as linhagens testadas foram consideradas suscet?veis; a cultivar Costel?o inclu?da como testemunha mostrou igual comportamento.