Dissertations / Theses on the topic 'Host disease resistance'
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Shafiei-Adjbisheh, Reza. "Genetic analysis of Arabidopsis non-host disease resistance." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/14381.
Full textCotter, Sheena C. "Trade-offs in insect disease resistance." Thesis, University of Stirling, 2002. http://hdl.handle.net/1893/26688.
Full textDonnelly, Ruairi. "Eco-evolutionary modelling of infectious disease and host resistance." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/2914.
Full textBrownlee, Helen Elizabeth. "Host-pathogen interactions in witches's broom disease of cocoa." Thesis, Aberystwyth University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333644.
Full textCox, Cindy Marie. "Cytogenetic characterization and disease resistance of perennial grasses and disease response to host diversity /." Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.
Full textEdwards, Suzanne Joy. "The mechanism of host resistance in celery to Septoria apiicola (Speg.)." Thesis, University of Liverpool, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357444.
Full textKrenz, Jennifer E. "Specificity of quantitatively expressed host resistance to Mycosphaerella graminicola /." Connect to this title online, 2007. http://hdl.handle.net/1957/3813.
Full textYu, Yong Gang. "Molecular genetic analysis of host resistance to soybean mosaic virus." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/37253.
Full textAsea, Godfrey Rox. "Genetic characterization of partial resistance and comparative strategies for improvement of host-resistance to multiple foliar pathogens of maize." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133833939.
Full textSellers, Scott Michael. "A quantitative analysis of Marek's disease virus in relation to host genetic resistance." Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394070.
Full textKang, Jeong-Gu. "Identification and characterisation of genes which underpin non-host disease resistance in Arabidopsis." Thesis, University of Edinburgh, 2007. http://hdl.handle.net/1842/12099.
Full textLough, Graham. "Should we aim for genetic improvement of host resistance or tolerance to infectious disease?" Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29510.
Full textSoriano, Imelda Rizalina. "Novel inducible phytochemical defences against plant parasitic nematodes /." Title page, table of contents and summary only, 2004. http://web4.library.adelaide.edu.au/theses/09PH/09phs7141.pdf.
Full textValdovinos, Ponce Guadalupe. "Molecular and cellular analyses of pathogenicity and host specificity in rice blast disease." Diss., Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/456.
Full textSandgren, Andreas. "Microbial factors and host responses affecting severity of pneumococcal disease and pneumococcal carriage /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-416-3/.
Full textAdu-Acheampong, Richard Kwame. "Pathogen diversity and host resistance in dieback disease of cocoa caused by Fusarium decemcellulare and Lasiodiplodia theobromae." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4670.
Full textSörén, Kaisa. "Experimental Schistosoma bovis infections in goats : studies on the host-parasite relationship with special reference to immunoregulatory effects and immunopathology /." Uppsala : Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200917.pdf.
Full textEllis, Margaret Lee. "The Soybean Seedling Disease Complex: Pythium spp. and Fusarium graminearum and their Management through Host Resistance." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322495401.
Full textTsai, Hsin Yuan. "Genomic basis of growth traits and host resistance against sea lice (L. Salmonis) in Atlantic salmon (S. Salar)." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28918.
Full textLee, Dayoung. "Towards a Multifaceted Understanding of Host Resistance and Pathogenicity in Rice Sheath Blight and Blast Diseases." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555510608170391.
Full textAshby, Ben. "The effects of contact patterns and genetic specificity on host and parasite evolution." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:3ea0e9dd-7960-4f33-ada5-437571e87873.
Full textAppiah, Alex Asante. "Variability of phytophthora species causing black pod disease of cocoa (Theobroma cacao L.) and implications for assessment of host resistance." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249294.
Full textRufener, George Keith. "A genetic and biochemical study of the antibiosis mechanism of host-plant resistance in soybeans to the Mexican bean beetle /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487335992902504.
Full textSon, Christina. "Use of tissue culture and molecular techniques to assess variation within Phytophthora citrophthora and screen for disease resistance in its citrus host." Adelaide Thesis (Ph.D.) -- University of Adelaide, 1992. http://hdl.handle.net/2440/21624.
Full textSon, Christina. "Use of tissue culture and molecular techniques to assess variation within Phytophthora citrophthora and screen for disease resistance in its citrus host." Thesis, Adelaide Thesis (Ph.D.) -- University of Adelaide, 1992. http://hdl.handle.net/2440/21624.
Full textJohnson, Colin Wolcott. "Comparative Susceptibility and Mechanisms of Resistance to Host Defense Peptides in Daptomycin-Susceptible and Non-Susceptible Clinical Isolates of Staphylococcus aureus." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/cmc_theses/1303.
Full textScott, Kelsey L. "Studies in the Management of Pythium Seed and Root Rot of Soybean: Efficacy of Fungicide Seed Treatments, Screening Germplasm for Resistance, and Comparison of Quantitative Disease Resistance Loci to Three Species of Pythium and Phytophthora sojae." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524147394255409.
Full textHall, Noemi Borsay. "Exploring Tuberculosis Genetics: Resistance to infection, progression to active disease, host genetics and Mycobacterium tuberculosis lineages within a household contact study in Kampala, Uganda." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1464787990.
Full textWidmark, Anna-Karin. "The late blight pathogen, Phytophthora infestans : interaction with the potato plant and inoculum sources /." Uppsala : Department of Forest Mycology and Pathology, Swedish University of Agricultural Sciences, 2010. http://epsilon.slu.se/201002.pdf.
Full textO'Connell, Dean Michael, and n/a. "Plant-arthropod interactions : domatia and mites in the genus Coprosma (Rubiaceae)." University of Otago. Department of Botany, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090807.160026.
Full textPeixoto, Cecília do Nascimento. "Estudos epidemiológicos do mal-do-pé (Gaeumannomyces graminis (Sacc.) von Arx & Olivier var. graminis) em arroz (Oryza sativa L.) de terras altas, no estado de Goiás." Universidade Federal de Goiás, 2006. http://repositorio.bc.ufg.br/tede/handle/tede/4196.
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The morphological and cultural characteristics of G. graminis var. graminis isolates from rice and grasses were studied. The fungus forms two types of mycelia, dark macrohyphae that join laterally to form runner hyphae or rhizomorphs and hyaline or infectious microhyphae, as well as fan shaped hyphae characteristic of the pathogen. Pigmented and lobed hyphopodia on lower leaf sheaths were formed both under natural conditions and artificial inoculations of plants. The perithecia containing asci and ascospores were found on leaf sheaths lesions on field samples. The perithecia were produced on leaf sheaths of inoculated plants as well as on detached sterilized leaf sheaths and on culture medium, potato-dextrose-agar (PDA). Hyphae and hyphopodia were formed from germination tubes of ascospores, and the hyphae under moist stress conditions produced chlamydospores which were initially hyaline and later attained dark color. The culture of Ggg, was characterized by fluffy aerial mycelium, white in the initial stages of growth and later with age, the colony color changed from dirty-white or mouse gray to almost black. The marked diagnostic colony characteristic of whorled appearance was the curling back of marginal hyphae. The amount and time of formation of perithecia varied among the isolates tested. The virulence test conduced with 20 isolates of rice and grasses, showed differences in aggressiveness both on rice seedlings and adult plants. In general, isolates from rice were more aggressive on rice than isolates from grasses. The test with four levels of inoculum (0, 5, 1.0, 2.0, 4.0 g per plant of autoclaved sorghum grains) and two plant ages showed that 60-day old were more susceptible than 35-day old plants. The spontaneous infection of healthy plants was observed in the greenhouse indicating the role of ascospores in the dissemination of black sheath rot in rice. Furthermore, the pathogenicity of ascospores of Ggg on rice plants was confirmed by inoculations tests. Six fields of upland rice were surveyed in the advanced stages of maturation for the incidence of black sheath rot. The disease incidence on tillers, under natural conditions of infection, ranged from 68 to 100%. The pathogenicity of 20 isolates retrieved from rice and grasses were studied. All isolates were pathogenic to rice and grasses such as baranyard grass (Echinochloa crusgalli), fountain grass (Pennisetum setosum) signal grass (Brachiaria sp), crab grass (Digitaria horizontalis), plantain signal grass (Brachiaria plantaginea), indian goose grass (Eleusine indica) and southern sandbur (Cenchrus echinatus). Winter cereals such as wheat, oat, rye, barley and triticale as well as sorghum, corn, and millet exhibited different degrees of susceptibility to the isolate Ggg-a 01. Significant differences were observed in relation to characteristic symptoms on the culm, lesion height, number of tillers or dead plants, presence of characteristic mycelium, fan shaped hyphae, production of hyphopodia and perithecia. The formation of perithecia was not observed on leaf sheaths of inoculated plants of millet, sorghum, southern sandbur and maize. All inoculated wheat plants were killed indicating more susceptibility than other cereals. The resistance of 58 upland rice genotypes were tested in the greenhouse, utilizing rice isolate Ggg-a 01. Of the genotypes assessed, the lesion height of SCIA16 and SCIA08 was significantly shorter compared to the highly susceptible genotype CNAS10351. The progress and dissemination of black sheath rot in rice was studied during two years under field conditions in savanna sensu lato ‘cerrado’. The central line of each plot was inoculated with isolate of Ggg to establish the infection foci. The soil was infested with four levels of inoculum (5.0, 10.0, 20.0 and 40.0 g of autoclaved sorghum grains containing mycelium / 40 cm) and main tiller of plants (4, 8, 16 and 32, tillers per plot/ 40 cm) were inoculated with 2.0 cm-long detached leaf sheaths containing perithecia by insertion between the culm and leaf sheath of the tiller. There was no significant effect of inoculum level on the disease severity obtained by soil infestation with mycelium as well as the plants infected with perithecia. However, the total area under disease progress curve was significantly smaller for plant infection with perithecia than for soil infestation by mycelium, during 2002/2003. The evaluation of disease incidence for the analysis of gradients was based on infected tillers in 1.6 square meter area, five lines on either side of the inoculated 40 cm-long central line. The analysis according models of Gregory (1968) and Kiyosawa & Shiyomi (1972) showed the existence of gradients in the first year, both for levels of inoculum of soil infection by mycelium and plant infection with perithecia. In the second year (2004/2005), there was no well defined gradient for all the treatments. The disease progress was not affected by inoculum levels on soil or plant infections. Monomolecular model was found more adequate in tests conduced under greenhouse conditions while the models of Gompertz and monomolecular, better described the disease progress under field conditions.
Foram estudadas características morfológicas e culturais de isolados de Gaeumannomyces graminis var. graminis provenientes de arroz e capins. O fungo se estabelece formando dois tipos de hifas: macrohifas, escuras, superficiais que se juntam lateralmente e formam cordões ou rizomorfas e microhifas, hialinas ou infecciosas, que penetram no hospedeiro. Forma também hifas em leque sobre as bainhas, a partir de macrohifas, que caracterizam o patógeno. Houve a formação de hifopódios lobados e pigmentados em bainhas, tanto em condições naturais como em inoculações. Observou-se peritécios contendo ascas e ascósporos, característicos do fungo, nas bainhas sobre as lesões em amostras coletadas no campo. Através de inoculação artificial, foram produzidos peritécios em bainhas de plantas, em bainhas destacadas e esterilizadas e em meio de cultura de batata-dextrose-ágar (BDA). Foram formadas hifas e hifopódios a partir de tubos germinativos dos ascósporos e as hifas crescidas em condições de estresse hídrico produziram clamidósporos, inicialmente hialinos e, posteriormente, de coloração escura. O micélio de Ggg, geralmente de aspecto aéreo fofo, é branco no início do crescimento, com variação de cor com a idade, do branco cinza ao marrom oliváceo e quase preto. Uma característica marcante é a aparência espiralada das macrohifas escuras nas bordas da colônia. Entre os isolados testados houve variação na quantidade de peritécios bem como na época de formação. Os testes de virulência realizados com vinte isolados provenientes de arroz e capins apresentaram diferenças em agressividade, tanto em plântulas quanto em plantas de arroz. Em geral, os isolados provenientes de arroz foram mais agressivos em arroz que os isolados de capins. O teste com quatro níveis de inóculo (0,5, 1,0, 2,0, e 4,0 g de inóculo por planta, multiplicado em grãos de sorgo autoclavados) e duas idades de plantas mostrou que as plantas inoculadas aos 60 dias após o plantio foram mais suscetíveis do que aquelas inoculadas aos 35 dias, requerendo menor nível de inóculo para a infecção. A patogenicidade de ascósporos de Ggg em plantas de arroz foi comprovada, bem como o papel dos ascósporos na disseminação do mal-do-pé do arroz. A incidência de mal-do-pé em lavouras de arroz de terras altas nas condições naturais de infecção variou de 68 a 100% de perfilhos infectados, entre seis lavouras avaliadas em fase avançada de maturação. Foi estudada também a patogenicidade dos vinte isolados de Ggg obtidos, provenientes de arroz e capins. Todos os isolados foram patogênicos a arroz e aos capins: capim arroz (Echinochloa crusgalli), capim avião (Pennisetum setosum), capim braquiária (Bachiaria sp.), capim digitaria (Digitaria horizontalis), capim marmelada (Brachiaria plantaginea), capim pé-degalinha (Eleusine indica) e capim timbete (Cenchrus echinatus). Os cereais de inverno, trigo, aveia, centeio, cevada e triticale, bem como sorgo, milho, e milheto apresentaram diferentes graus de suscetibilidade ao isolado Ggg-a 01. As diferenças foram significativas quanto a sintomas típicos na base do colmo, altura de lesão escura na bainha, número de perfilhos ou plantas mortas, presença de micélio característico, hifas em leque e produção de hifopódios e peritécios. Não foram observados peritécios em milheto, sorgo, timbete e milho e a maior suscetibilidade foi apresentada pelo trigo, com a morte de todas as plantas inoculadas. Foi testada a resistência de 58 genótipos de arroz de terras altas, utilizando o isolado Ggg-a 01 proveniente de arroz, em casa-de-vegetação. Entre os genótipos avaliados, SCIA16 e SCIA08 apresentaram altura de lesão significativamente menor, sendo considerados resistentes em relação ao genótipo CNAS10351, altamente suscetível. O progresso e disseminação do maldo- pé do arroz foram estudados durante dois anos, em condições de campo em solo de cerrado. Utilizou-se delineamento experimental de blocos completos ao acaso e quatro repetições. Cada parcela foi constituída de dezenove linhas de sete e cinco metros, respectivamente no primeiro e segundo ano, com espaçamento de quarenta centímetros. Foi inoculada a linha central de cada parcela com isolado de Ggg para estabelecer os focos de disseminação da doença. O solo foi infestado com micélio em quatro níveis de inóculo (5,0, 10,0, 20,0 e 40,0 gramas de grãos de sorgo autoclavados e colonizados com micélio / 40 cm da linha) e perfilhos foram inoculados (4, 8, 16 e 32 perfilhos / 40 cm da linha) com pedaços de bainhas de arroz de dois centímetros de comprimento, contendo peritécios e micélio, inseridos entre o colmo e a bainha. Não houve efeito de níveis de inóculo na severidade da doença, tanto para micélio no solo quanto para peritécios na planta, nos dois anos de experimento. Entretanto, a área total sob a curva de progresso da doença na safra 2002/2003 foi significativamente menor nas plantas infectadas com peritécios, do que nas plantas infectadas através de infestação do solo com micélio. A avaliação de incidência da doença para análise do gradiente foi baseada nos perfilhos contados em 1,6 metros quadrados, compostos de cinco linhas de quarenta centímetros de cada lado da fonte de inóculo, na linha central. A análise de gradiente, conforme modelos de Gregory (1968) e Kiyosawa & Shiyomi (1972) mostrou existência de gradiente no primeiro ano, tanto para níveis de inóculo quanto para os focos provenientes dos dois tipos de inóculo. No segundo ano (2004/2005), não houve gradiente definido para os tratamentos testados. O progresso da doença não foi afetado pelos níveis, tanto na infecção do solo com micélio, quanto na planta com peritécios. Em teste de ajuste de modelo matemático para estudos epidemiológicos, o modelo monomolecular foi o mais apropriado para estudos de mal-do-pé do arroz nas condições de casa-de-vegetação e os modelos de Gompertz e monomolecular são os que melhor descrevem o progresso da doença, nas condições de campo.
Kidane, Yared H. "The Landscape of Host Transcriptional Response Programs Commonly Perturbed by Infectious Pathogens: Towards Host-Oriented Broad-Spectrum Drug." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77368.
Full textPh. D.
Kidane, Yared Habteselassie. "The Landscape of Host Transcriptional Response Programs Commonly Perturbed by Infectious Pathogens: Towards Host-Oriented Broad-Spectrum Drug." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/77368.
Full textPh. D.
Fry, Andrew E. "Genome mapping of malaria resistance genes : the host ligands of PfEMP1." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:df1ffe4b-ba67-4fc6-9024-b278b887d4f9.
Full textThurston, Graham S. (Graham Stanley) 1958. "Host plant resistance and entomogenous nematodes for controlling the northern corn rootworm, Diabrotica barberi (Coleoptera: Chrysomelidae)." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66175.
Full textPathi, Krishna [Verfasser]. "Establishment of maize resistance to fungal diseases by host-induced gene silencing and site-directed mutagenesis / Krishna Pathi." Hannover : Gottfried Wilhelm Leibniz Universität, 2021. http://d-nb.info/1235138437/34.
Full textVatter, Heather. "Analysis of Simian Hemorragic Fever Virus Proteins and the Host Cell Responses of Disease Resistant and Susceptible Primates." Digital Archive @ GSU, 2013. http://digitalarchive.gsu.edu/biology_diss/128.
Full textLuczynski, Anna. "Chemical and morphological factors of resistance against the twospotted spider mite (Tetranychus urticae Koch) in beach strawberry Fragaria chiloensis (L.) Duchesne." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/27981.
Full textLand and Food Systems, Faculty of
Graduate
Bahlmann, Lieschen. "Factors affecting the resistance mechanisms of the Russian wheat aphid (Diuraphis noxia) on wheat." Diss., University of Pretoria, 2002. http://hdl.handle.net/2263/28470.
Full textLE, COZ SERGE. "La rhizomanie de la betterave sucriere : multiplication du virus et aspects agronomiques de la maladie." Paris 6, 1986. http://www.theses.fr/1986PA066644.
Full textMassacci, Francesca Romana. "Enteric disorders at weaning : age, amoxicillin administration and Enterotoxigenic Escherichia coli infection affecting the gut microbiota of piglets Late weaning is associated with increased microbial diversity and higher Faecalibacterium prausnitzii abundance in piglet’s fecal microbiota Host genotype and amoxicillin administration affect the incidence of diarrhoea and faecal microbiota of weaned piglets during a natural multi-resistant ETEC infection." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS073.
Full textIn pig production systems, weaning is a crucial period characterized by nutritional, environmental and social stress. During this process, piglets are susceptible to diarrhoea and the gut ecosystem needs to adapt to dietary changes, from a milk-based diet to a solid and more complex cereal-based feed, and to environmental pathogen pressure. One of the most important etiological agent of the post-weaning diarrhoea (PWD) is the Enterotoxigenic Escherichia coli (ETEC) able to cause severe outcomes and considerable economic losses to farmers worldwide. A role of host genetics in infection appearance is well-established, the SNPs located on the Mucine 4 (MUC4) and Fucosyltransferase 1 (FUT1) genes being associated with the susceptibility to ETEC F4 and ETEC F18, respectively.To investigate aspects related to weaning diarrhoea, two studies have been performed. The aim of the first study was to evaluate the impact of weaning age on gut microbiota diversification in piglets comparing animals at different weaning ages. Forty-eight Large White piglets were divided into four groups of 12 animals weaned at 14 days old (early weaning), 21 or 28 days old (main weaning ages in pig intensive farming) and 42 days old (late weaning). In each group, faecal bacteria composition was assessed by sequencing the 16S rRNA gene of faecal DNA on the weaning day, 7 days post-weaning and at 60 days of age. Our results showed that late weaning increases the gut microbiota diversity including a higher abundance of Faecalibacterium prausnitzii, reported as beneficial in humans. Our results suggest than the pre-weaning gut microbiota composition conferred by a late weaning at 42 days of age could enhance gut health in piglets. This would provide a competitive advantage to piglets accumulating a higher diversity of potentially beneficial microbes prior to the stressful and risky weaning transition.The aim of the second study was to evaluate the effects of the host-genotype and different routes of amoxicillin administration on the presence of diarrhoea and the microbiota composition, during a natural infection by multi-resistant ETEC strains in weaned piglets. For this purpose, seventy-one piglets were divided into three groups: two groups differing by amoxicillin administration routes – parenteral (P) or oral (O) and a control group without antibiotics (C). Our results confirmed the MUC4 and FUT1 as host genetic markers for the susceptibility to ETEC infections. Moreover, our data highlighted that amoxicillin treatment may produce adverse outcomes on pig health in course of multi-resistant ETEC infection and this effect is stronger when the antibiotic is orally administered than parenterally.Both studies highlighted the importance of alternative control measures related to farm management in controlling weaning related diarrhoea. With a need to limit the use of antibiotics, selection of resistant genotypes, next-generation probiotics supplementation in feed, and correct procedures of weaning age, should be considered in farm management practices in order to preserve a balanced and stable gut microbiota and consequently reduce occurrence of diarrhoea at weaning
Lo svezzamento rappresenta un momento cruciale nell’allevamento suinicolo ed è caratterizzato da stress nutrizionale, ambientale e sociale. In questa fase, i suinetti risultano a maggior rischio di insorgenza di diarrea in quanto la microflora intestinale deve adattarsi ai cambiamenti alimentari legati al passaggio da una dieta a base lattea ad un alimento solido a base di cereali e più complesso e all’elevata pressione infettiva ambientale. Uno dei più importanti agenti eziologici responsabili della diarrea post-svezzamento (PWD) è Escherichia coli Enterotossigeno (ETEC) in grado di provocare gravi quadri clinici nonché ingenti perdite economiche per gli allevatori. Che ci sia una componente genetica nell'evoluzione di queste infezioni è stato ben definito attraverso l’individuazione degli SNP situati sui geni Mucine 4 (MUC4) e Fucosyltransferase 1 (FUT1) associati rispettivamente alla suscettibilità nei confronti di ETEC F4 e ETEC F18. Nella presente tesi sono illustrati due studi che hanno avuto l’obiettivo di approfondire alcuni aspetti legati alla comparsa di diarrea durante lo svezzamento. Lo scopo del primo studio è stato quello di valutare l'impatto dell'età di svezzamento sulla diversità del microbiota intestinale, confrontandone la composizione in suinetti svezzati a diverse età. Quarantotto suinetti di razza Large-White sono stati suddivisi in quattro gruppi da 12 soggetti, svezzati rispettivamente a 14 giorni di età (svezzamento precoce), a 21 o 28 giorni (età di svezzamento principale nell'allevamento intensivo) e a 42 giorni (svezzamento tardivo). In ogni gruppo è stata valutata la composizione batterica fecale il giorno dello svezzamento, 7 giorni post-svezzamento e a 60 giorni di età, sequenziando il gene 16S rRNA dal DNA batterico fecale. I risultati ottenuti hanno evidenziato come lo svezzamento tardivo aumenti il grado di diversificazione del microbiota intestinale, aumentando l’abbondanza di Faecalibacterium prausnitzii, già considerato benefico per l'uomo. Emerge, inoltre, come la composizione del microbiota intestinale nel pre-svezzamento associata allo svezzamento tardivo incrementi il livello di salute intestinale nei suinetti. Tale condizione, comporterebbe un notevole vantaggio per gli animali che acquisiscono una maggiore differenziazione del microbiota intestinale, incrementando l’abbondanza di batteri beneficiali prima di affrontare lo stress dello svezzamento. Lo scopo del secondo studio è stato quello di valutare gli effetti del genotipo dell’ospite e le vie di somministrazione dell’amoxicillina sulla comparsa della diarrea e sulla composizione del microbiota intestinale, durante un'infezione naturale causata da ETEC multi-resistente, in suinetti svezzati. A tale scopo, settantuno suinetti sono stati divisi in tre gruppi: due gruppi diversificati dalla via di somministrazione dell’amoxicillina - parenterale (P) o orale (O), e un terzo gruppo di controllo in cui non sono stati somministrati antibiotici (C). I risultati ottenuti hanno confermato il ruolo di MUC4 e FUT1 quali marcatori genetici di suscettibilità alle infezioni da ETEC. Inoltre, i nostri dati hanno evidenziato come la somministrazione di amoxicillina possa influenzare negativamente lo stato di salute dei suini in corso di infezione da ETEC, effetti ancora più evidenti quando la somministrazione antibiotica avviene per via orale. Entrambi gli studi hanno sottolineato l'importanza di adottare misure alternative legate al management aziendale per il controllo della diarrea post-svezzamento. Nell’ottica di limitare l'utilizzo di antibiotici, azioni quali la selezione di genotipi resistenti, l'integrazione di probiotici di nuova generazione nei mangimi ed una corretta gestione dell’età di svezzamento, dovrebbero essere prese in considerazione nelle pratiche gestionali aziendali al fine di preservare un microbiota intestinale equilibrato e stabile e di conseguenza ridurre l'insorgenza di diarrea allo svezzamento
Picard, Sánchez María Amparo. "Control of enteric parasitic diseases of farmed gilthead sea bream: New insights into Enteromyxum leei (Myxozoa) and Enterospora nucleophila (Microsporidia) infections." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/167035.
Full text[CA] La producció en aqüicultura s'ha vist minvada per aparició de malalties en els sistemes de cria de peixos. En concret, en l'orada (Sparus aurata), hi ha dos paràsits destacats: Enteromyxum leei (Myxozoa) i Enterospora nucleophila (Microsporidia). Fins avui, per a cap dels dos s'ha establert un cultiu in vitro, i només per a E. leei s'ha aconseguit establir un model de manteniment de la infecció in vivo. La present tesi pretén incrementar el coneixement sobre aquests paràsits i les seves relacions amb l'hoste, establint les bases per a generar solucions que puguin ser aplicades en l'aqüicultura. L'objectiu amb E. leei va ser estudiar la immunitat adquirida induïda en l'orada i la possibilitat de generar eines de diagnòstic i vacunes enfront d'aquesta malaltia. Per a això, primer es va demostrar la resistència del peix al paràsit després d'una segona exposició, la qual va durar fins a 16 mesos. A més, la resistència sembla estar correlacionada amb alts nivells d'immunoglobulina (Ig) M específica en sang, i una alta expressió de Igs, fins i tot abans de la re-exposició al paràsit. El següent pas va ser afinar el protocol d'infecció amb E. leei. Els resultats van mostrar que una setmana és suficient per a transmetre la infecció de E. leei per efluent, independentment de la temperatura. Després de la demostració de la resposta adaptativa eficaç enfront de E. leei, i en disposar d'un model d'infecció refinat, es va realitzar un assaig d'immunització passiva. Aquí, els resultats van mostrar que els anticossos específics efectivament aconsegueix alentir la invasió de l'intestí pel paràsit i disminuir els símptomes de la malaltia. Paral·lelament, el resultat de l'anàlisi del repertori de les regions variables de la IgM i IgT de l'intestí peixos resistents va mostrar la inducció d'una resposta policlonal en les cèl·lules B. Sobre la base d'aquests resultats, es va realitzar una cerca d'antígens de E. leei que poguessin ser utilitzats com a candidats per a la producció de vacunes (anàlisis proteómico) o eines de diagnòstic (anàlisi in silico). Per a això, es va assemblar un transcriptoma de novo utilitzant una mostra mixta d'intestí d'orada i paràsit. Els resultats van donar lloc a 7 i 12 candidats en la cerca in silico i proteòmica, respectivament. En els estudis de E. nucleophila, pel fet que va ser descrita molt recentment, el punt de partida va ser més bàsic. Les mostres d'aquest paràsit només es poden obtenir de brots naturals en piscifactorias. Per això, primer es va realitzar un estudi de caracterització de la patologia de la infecció a partir de peixos infectats naturalment. En etapes primerenques de la infecció, el paràsit es localitza principalment en l'intestí, però mesos després, la prevalença en intestí baixa i incrementa en els òrgans hematopoètics i l'estómac. Els signes clínics de la infecció van consistir en una reducció significativa del creixement, emaciació, i pal·lidesa de les parets intestinals. A nivell cel·lular, en els casos més greus es va observar hipercelularidad en l'epiteli intestinal i proliferació de cèl·lules rodlet, un elevat nombre de limfòcits en la base de l'epiteli i infiltració de granulòcits acidòfils en l'epiteli intestinal. Finalment es van provar diverses formes de transmissió horitzontal de E. nucleophila (cohabitació, efluent, intubació oral i anal) amb per a desenvolupar un model de manteniment in vivo. Es va aconseguir la transmissió el paràsit per totes les vies, però amb una disminució de prevalença al llarg del temps. Variables com la temperatura, la dosi, i l'estat dels peixos donants semblen ser més determinants que la ruta seleccionada per a la transmissió. Entre les rutes provades, la intubació anal sembla ser la més prometedora, però cap d'elles va ser capaç de reproduir els signes clínics observats en les infeccions naturals.
[EN] Aquaculture production is hampered by the emergence of parasite diseases in fish farming systems. Among them, in Sparus aurata, there are two important enteric parasites described: Enteromyxum leei (Myxozoa) Enterospora nucleophila (Microsporidia). To date, no in vitro culture has been established for either parasite, and only for E. leei was it possible to establish a model for maintaining the infection in vivo. The aim of this thesis is to gain new knowledge about these parasites and their relationship with the host, also the basic foundations for generating solutions that can be applied in aquaculture. The general objective for E. leei was to study the acquired immunity induced in gilthead bream and the possibility of generating diagnostic tools and vaccines against this disease. To this end, resistance against the parasite was assessed with a second exposure against the parasite, which showed a resistance for at least 16 months. Besides resistance seemed to be correlated with high levels of specific immunoglobulin (Ig) M in blood, and a high expression of Igs, in particular, the soluble forms, even before re-exposure to the parasite. The next step was refining the protocol for effluent infection with E. leei by studying infection at different exposure time points, temperatures and population densities. The results showed that one week of exposure is sufficient to spread E. leei infection by effluent, regardless of temperature. After demonstrating the resistance against E. leei, and with a refined infection model, a passive immunization assay was performed. The results showed that the serum with specific antibodies effectively slows down the invasion of the gut by the parasite and reduces the symptoms of the disease. At the same time, the analysis of the repertoire of the variable regions of intestinal IgM and IgT showed an induction of a polyclonal response in B cells. On the basis of these results, a research was carried out for E. leei antigens that could have use as candidates for the production of vaccines (proteomic study) or diagnostic tools (in silico study) using the parasite transcriptomic data. To do this, a de novo transcriptome was assembled using a mixed sample of gilthead sea bream and parasite, with a posterior filtrate of the sequences. The In silico and proteomic analysis search resulted in 7 and 12 transcripts, respectively, which are being used for diagnostic and vaccine production. The starting point was more basic in E. nucleophila studies, since this is a recently described disease. The samples of this parasite can only be obtained from natural outbreaks in fish farms. Therefore, first study was carried out to characterize the pathology of the infection of naturally infected fish. In the early stages of the infection, the parasite is mainly located in the intestine, but months later, the prevalence is lower in the intestine and increases in the hematopoietic organs and the stomach. Clinical signs of infection were significant reduction in growth, wasting, and intestinal walls paleness. At the cellular level, in the most severe cases hypercellularity in the intestinal epithelium, proliferation of rodlet cells, high number of lymphocytes at the base of the epithelium and infiltration of acidophilic granulocytes in the intestinal epithelium were observed. Finally, horizontal transmission of E. nucleophila was tried using different transmission methods: cohabitation, effluent, and oral and anal intubation. Transmission of the parasite was achieved with all routes, but there was a decrease in prevalence over time in all cases except for the anal route. Variables such as temperature, dose, and the status of the donor fish appear to be more important than the selected route. Among the routes tested, anal intubation seemed to be the most promising, as it was sustained over a longer period of time, but none of them was able to reproduce the same clinical signs of infection observed in natural infections.
The authors kindly acknowledge the collaboration of anonymous fish farming companies allowing access to the animals during the disease outbreaks. We thank J. Monfort and L. Rodríguez (IATS-CSIC) for the technical assistance on histological processing.This work has been carried out with financial support from the European Union and the Spanish Ministry of Economy and Competitiveness (MINECO) under grant projects ParaFishControl (H2020-634429) and AGL2013-R-48560-C2-2-R, respectively. APS was contracted under ParaFishControl project. Primer sequences and access to the gilthead sea bream transcriptomic database were kindly provided by Prof. J. Pérez-Sánchez of the IATS- Nutrigenomics group. The authors thank I. Vicente for fish maintenance and technical assistance during samplings. The authors thank P. Boudinot (INRAE) for his help in designing and interpreting the immunoglobulin repertoire study and results, J. Pérez-Sánchez (IATS-CSIC) for providing access to the gilthead sea bream genome sequences to perform the repertoire analysis.This work was funded by the European Research Council (ERC Consolidator Grant 2016 725061 TEMUBLYM).
Picard Sánchez, MA. (2021). Control of enteric parasitic diseases of farmed gilthead sea bream: New insights into Enteromyxum leei (Myxozoa) and Enterospora nucleophila (Microsporidia) infections [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/167035
TESIS
Cowger, Christina. "Effects of host resistance on Mycosphaerella graminicola populations." Thesis, 2002. http://hdl.handle.net/1957/32370.
Full textGraduation date: 2002
Collins, Susie. "Co-evolution of host and virus : mechanisms of host resistance and virus attenuation." Phd thesis, 2004. http://hdl.handle.net/1885/146268.
Full textCarpane, Pablo Daniel. "Host resistance and diversity of Spiroplasma kunkelii as components of corn stunt disease." 2007. http://digital.library.okstate.edu/etd/umi-okstate-2564.pdf.
Full textSoriano, Imelda Rizalina. "Novel inducible phytochemical defences against plant parasitic nematodes / Imelda Rizalina Soriano." Thesis, 2004. http://hdl.handle.net/2440/22121.
Full textBibliography: leaves 146-169.
vi, 169 leaves : ill, (some col.), photos (col.) ; 30 cm.
Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2004
Hayes, Matthew Allan. "Identification of host genes involved in the biotrophic interaction between grapevine and powdery mildew." Thesis, 2006. http://hdl.handle.net/2440/37876.
Full textThesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006.
Ming, Reiguang. "Restriction fragment length polymorphism analysis of host-plant resistance to four maize pathogens." Thesis, 1995. http://hdl.handle.net/10125/9273.
Full textHou, Yi-Hsuan, and 侯逸萱. "Host-induced gene silencing targeting the calcineurin of Fusarium fujikuroi to enhance resistance against rice bakanae disease." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8qy74u.
Full text國立臺灣大學
植物病理與微生物學研究所
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Bakanae or foolish seedling disease of rice is caused by the ascomycetous fungus Fusarium fujikuroi, of which is widespread in many rice growing areas. Current protection strategies rely on the fungicides, but this results in chemical-resistant F. fujikuroi and other undesirable environmental effects. An alternative approach involving RNAi, termed host-induced gene silencing (HIGS), of which generating siRNA molecules in plants that target to the specific mRNAs of pathogens and thereby resulted in their degradation. Calcineurin belongs to a Ca2+/calmodulin-dependent phosphatase, which is comprised of heterodimer with a catalytic (Cna1) and a regulatory (Cnb1) subunits. There have been known that calcineurin mediates Ca2+ signaling that regulates the growth, stress responses and virulence in fungal kingdom. Based on pharmacological inhibition of calcineurin in F. fujikuroi, we found that calcineurin inhibitor FK506 or cyclosporinA can strongly inhibit the growth of F. fujikuroi. We therefore aim to determine whether repressing the expression of CNA1 or CNB1 gene in F. fujikuroi by the HIGS strategy in rice can enhance resistance against bakanae disease. By using Agrobacterium-mediated gene transformation strategy, the FfCNA1-Ri and FfCNB1-Ri constructs have been introduced into rice plants, respectively, and the copy number of transgenes were analyzed by Southern blot hybridization in the transgenic lines. Based on the pathogen inoculation assay and fungal biomass quantification, results showed that the transgenic rice plants that carry the FfCNA1-Ri or FfCNB1-Ri constructs increased resistance against bakanae disease, promising its potential use in the future.
Gludovacz, Thomas. "Clubroot in canola and cabbage in relation to soil temperature, plant growth and host resistance." Thesis, 2013. http://hdl.handle.net/10214/6660.
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