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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

The role of the daf-8 gene in Caenorhabditis elegans dauer larva development /

Estevez, Annette Orene Zager, January 1997 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 122-131). Also available on the Internet.
22

The role of the daf-8 gene in Caenorhabditis elegans dauer larva development

Estevez, Annette Orene Zager, January 1997 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 122-131). Also available on the Internet.
23

Análise funcional de proteínas efetoras de Meloidogyne incognita com potencial aplicação no controle de fitonematoides

Mezzalira, Itamara 15 March 2013 (has links)
Dissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Biologia Celular, Programa de Pós-Graduação em Biologia Molecular, 2013. / Submitted by Luiza Silva Almeida (luizaalmeida@bce.unb.br) on 2013-07-30T20:15:42Z No. of bitstreams: 1 2013_ItamaraMezzalira.pdf: 1833540 bytes, checksum: 37510b82177c627dc73b548a5947cd12 (MD5) / Approved for entry into archive by Leandro Silva Borges(leandroborges@bce.unb.br) on 2013-08-02T20:18:11Z (GMT) No. of bitstreams: 1 2013_ItamaraMezzalira.pdf: 1833540 bytes, checksum: 37510b82177c627dc73b548a5947cd12 (MD5) / Made available in DSpace on 2013-08-02T20:18:11Z (GMT). No. of bitstreams: 1 2013_ItamaraMezzalira.pdf: 1833540 bytes, checksum: 37510b82177c627dc73b548a5947cd12 (MD5) / Nematoides formadores de galhas (NFG) (Meloidogyne spp.) são endoparasitas biotróficos que possuem uma ampla gama de hospedeiros. O sucesso do parasitismo dos NFG depende da indução e manutenção de sítios de alimentação altamente especializados que são compostos por células gigantes. Os NFG produzem uma série de proteínas nas glândulas secretoras e as injetam, via estilete, nas células da planta hospedeira para manipular o seu metabolismo. Elucidar o papel das proteínas secretadas é essencial para o entendimento das bases moleculares do processo de parasitismo dos nematoides, bem como para o desenvolvimento de novas estratégias para o controle destes parasitas. Este trabalho é o início de uma análise detalhada sobre o papel que três proteínas efetoras de M. incognita, MSP2, MSP7 e MSP18, desempenham na interação com arroz (Oryza sativa). Os genes de parasitismo de M. incognita MSP2, MSP7 e MSP18 codificam para proteínas de 210, 176 e 172 aminoácidos, respectivamente, são expressos nas glândulas secretoras do nematoide e possuem peptídeo sinal de secreção na extremidade N-terminal. A análise de expressão através de qRT-PCR mostrou que estes genes apresentam diferentes padrões de expressão durante interação planta-nematoide, sendo que MSP2 tem seu pico de expressão na fase inicial de estabelecimento do parasitismo, enquanto MSP7 e MSP18 são expressos ao longo de todo o ciclo de parasitismo. Resultados de experimentos de transformação transiente de células da epiderme de cebola, via biobalística, mostraram que o produto da fusão MSP2-EGFP apresentou forte sinal de fluorescência no núcleo, enquanto que os produtos das fusões MSP7-EGFP e MSP18-EGFP mostraram sinal de fluorescência no citoplasma e no núcleo da célula vegetal. Estes resultados mostram que estas proteínas são direcionadas a diferentes compartimentos subcelulares da célula vegetal. Foram obtidas plantas transgênicas de arroz (O. sativa cv. Nipponbare) expressando as proteínas MSP2, MSP7 e MSP18, sem o peptídeo sinal de secreção, e micro-RNAs artificiais (amiRNAs) capazes de silenciar a expressão dos genes corespondentes no nematoide. Para cada gene estudado, dois amiRNAS foram selecionados. Para cada construção uma média de 24 plantas transgênicas foram obtidas. Análises de Southern-blot and qPCR foram realizadas para identificar plantas T0 com apenas uma cópia do transgene e para cada construção foram selecionadas três linhagens T1 para avanço de geração e, posterior, realização de bioensaios. A análise do processo de infecção das plantas transgênicas por M. incognita irá permitir a identificação de genes essenciais para o estabelecimento do parasitismo. Os dados obtidos nestas análises irão ampliar o conhecimento sobre as proteínas efetoras de fitonematoides e trazer novas possibilidades para o desenvolvimento de estratégias de controle de Meloidogyne spp. em arroz e outras culturas de interesse. _______________________________________________________________________________________ ABSTRACT / Root-knot nematodes (RKN) (Meloidogyne spp.) are endo-parasites with a wide host range. Effector proteins, produced in the nematode esophageal gland cells and released in the host plant cells through stylet, dramatically modify selected plant cells into giant-cells, which are the permanent food source to the sedentary nematode. Elucidating the role of different nematode effectors is essential to understanding the molecular basis of nematode parasitism as well as to developing new nematode control strategies. This study is the beginning of an extensive analysis to assess the functional role of three M. incognita effector proteins, MSP2, MSP7 and MSP18, during rice-nematode interaction. The coding sequence of MSP2, MSP7 and MSP18 encoded proteins with 210, 176 e 172 amino acids, respectively, including N-terminal signal peptides. These genes are expressed exclusively in the nematode esophageal gland cells. qPCR analysis of transcript accumulation showed that MSP2, MSP7 and MSP18 genes displayed different expression patterns during host infection. MSP2 reaches the maximum expression level in the beginning of parasitism cycle. MSP7 and MSP18 are highly expressed during the whole parasitism cycle. To test the localization of MSP2, MSP7 and MSP18 in plant cells, a protein transient expression assay was performed. The fusion product of MSP2-GFP showed a strong fluorescence signal in plant nuclei, while the fluorescence signal of the MSP7-GFP and MSP18-GFP fusion products were observed in plant cytoplasm and nuclei. Reverse and forward genetic analyses were conducted to assess the role of the candidate proteins in plant-nematode interactions. We used rice (Oryza sativa cv. Nipponbare) to generate transgenic plants expressing MSP2, MSP7 and MSP18 full-length cDNAs or artificial micro-RNAs (amiRNAs) able to silence the cognate genes in the nematode. For each gene studied, two amiRNAs were selected to perfectly match the M. incognita candidate gene but not other nematode or plant sequences. For each construct, an average of 24 plants was recovered. Southern- blots and qPCR analyses identified single-copy gene (or amiRNA) constructs insertion in the genome of the transformed plants (T0 plants). Assessment of nematode growth and development on transgenic plants will allow selecting genes involved in establishing the compatibility with the host plant. Data obtained should significantly widen our knowledge of molecular players contributing to nematode pathogenicity, opening new avenues for Meloidogyne spp. control strategies in rice and other crops of interest which are highly susceptible to M. incognita.
24

Influence of habitat on the behaviour of entomopathogenic nematodes

Kruitbos, Laura Marina January 2009 (has links)
In seeking new hosts, entomopathogenic nematode foraging strategies are believed to range from sit-and-wait foragers (ambushers) to widely active foragers (cruisers).  This study investigated the behaviour, dispersal and competitive ability of entomopathogenic nematodes of the genera <i>Heterorhabditis </i>and <i>Steinernema </i>in relation to soil habitat. The host finding and competitive ability of <i>Steinernema carpocapsae, </i>an “ambusher” and <i>Heterorhabditis megidis, </i>a “cruiser” in two contrasting soil habitats (sand and peat) showed “habitat-specific” differences in foraging mode between the two species.  In peat, <i>S. carpocapsae </i>outcompeted <i>H. megidis </i>in terms of host finding, whereas the opposite was true in sand.  In the appropriate habitat, both nematodes showed behaviours not predicted by their supposed foraging strategy.  Experiments examining the interspecific interactions between <i>S. carpocapsae </i>and <i>H. megidis </i>also showed significant differences in the population dynamics between the two species in relation to habitat. Nictation behaviour is frequently cited as a host finding strategy in ambush foraging nematodes. The study confirms that ambush foraging species <i>S. carpocapsae </i>and <i>Steinernema scapterisci </i>frequently nictate, but show that habitat is an important factor regulating this behaviour.  This study also demonstrates the ability of the cruise foraging nematode, <i>H. megidis </i>to nictate on habitats not previously examined.
25

Influencia da idade da infecção de Strongyloides venezuelensis Brumpt, 1934 (Nematoda : Rhabditida) em ratos e de fatores ambientais externos no desenvolvimento das formas de vida livre

Pegoraro, Fabiola Isabela 17 September 1999 (has links)
Orientador: Marlene Tiduko Ueta / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-09-11T20:54:58Z (GMT). No. of bitstreams: 1 Pegoraro_FabiolaIsabela_M.pdf: 2516504 bytes, checksum: 84a06955a1006593e99d261088e22665 (MD5) Previous issue date: 1999 / Resumo: O nematódeo Strongyloides venezuelensis alterna, no decorrer do seu ciclo de vida, gerações parasita e de vida livre, sofrendo influência de fatores ambientais externos e outros relacionados ao hospedeiro vertebrado. A geração parasita é constituída somente por fêmeas adultas e a de vida livre por machos e remeas. Dos ovos eclodem larvas que se tomam filarióides por ciclo direto ou adultos sexuados por ciclo indireto. Parâmetros morfométricos das remeas parasitas e de larvas filarióides oriundas das culturas de carvão animal granulado, em intervalos de 7, 14 e 21 dias, serviram para evidenciar o grau de atuação de fatores do meio externo (quantidade de alimento nas culturas) e relacionados ao hospedeiro (sexo e idade). Os estudos foram feitos em 4 grupos experimentais, usando ratos Wistar, SPF, machos e remeas infectados, subcutaneamente, com 500 e 3500 larvas filarióides. Após o intervalo de 7, 14 e 21 dias, as larvas filarióides e as formas de vida livre foram recolhidas das culturas pelo método de Rugai e as formas parasitas do intestino dos ratos, por necrópsia dos animais. Ambas foram mortas pelo calor e fixadas em T AF. Posteriormente, 30 exemplares de larvas e fêmeas de cada dia de infecção de cada grupo foram desenhadas em câmara clara e medidas com curvímetro e mesa digitalizadora, para análise morfométrica. Sendo assim, nossos resultados evidenciaram que a idade e o sexo do hospedeiro podem alterar o comprimento e as proporções do esôfago e cauda nas larvas e o comprimento, o esôfago e a distância da abertura da vulva nos adultos. Os adultos obtidos de infecções em ratos mais velhos, apresentaram menor tamanho e nas infecções menos intensas o comprimento foi maior. O sexo do hospedeiro aparentemente não afetou o tamanho do adulto, exceto em infecções mais antigas; porém, produziu menor número de fêmeas de vida livre nos hospedeiros remeas. A duração e a intensidade da infecção no comportamento de Strongyloides venezuelensis no hospedeiro comprovou que, em infecções mais antigas, aumenta o número de formas de vida livre em cultura, principalmente em ratos mais velhos. Neste trabalho, o meio de cultura demonstrou influenciar o aparecimento das formas de vida livre, principalmente onde houve maior disponibilidade de alimento nas fezes dos hospedeiros, que faziam parte do meio de cultura (3 partes de carvão: 1 parte de fezes) / Abstract: " Influence of the infection age of Strongyloides venezuelensis Brumpt, 1934 (Nematoda : habditida) and external environrnental factors in free -living forms development" During its life cycle, the nematode Strongyloides venezuelensis alternates, parasite and free - living generations, under influence of external environrnental factors and others related to vertebrate host. The parasite generation is composed of only adults female and free - living for males and females. As of eggs hatches larvae becoming infective larvae by direct cycle or sexual adults by indirect cycle. Morfometric parameters of females adults and the infective larvae derived from animal granulated charcoal cultures, at space between 7, 14 and 21 days, served for evidence the grade of actuaction the external environmental factors (quantity for food in the cultures) and related for host (sex and age). The studies were done with 4 experimental groups, utilized Wistar rats, SPF, males and females infected, subcutaneously, with 500 and 3500 infective larvae. In the space of 7th, 14th and 21th days, the infective larvae and free - living forms went removed in the cultures by Rugai's method and parasites forms from rats intestine, by necropsy for animaIs. Both killed for heat and fixed in TAF. Posteriorly, thirty larvae and adult females examples in every infection day in each group went pictured in camera lucida and measured with curvimeter and digital board, for morfometric analysis. Thus, our results evidenced wich the age and the host sex can be change the length and the esophagus and tail proportions in the larvae and the lenght, esophagus and the vulva opening in the adults. The adults derived by infections in older rats, presented smaller size and in less intensive infections the length were higher. Apparently, the host sex don't to affect the adult size, except in older infections; but produced a minor number of free ­ living females from female hosts. The duration and the intensity of infection Strongyloides venezuelensis in the host behaviour wished corroborate which, in older infections, increase the number of free ­living forms in culture, mainly in older rats. In this work, the culture medium showed the development of free - living forms, mainly where there was high disponibility of food in the feces hosts as part of culture medium ( 3 charcoal parts : 1 feces) / Mestrado / Mestre em Parasitologia
26

Agchylostoma conepati nova species parásito del Conepatus suffocans Azara 1801 (Zorrino) /

Solanet, Emilio, January 1911 (has links)
Thesis--Universidad Nacional de Buenos Aires, 1911. / Includes bibliographical references (p. 171-172) and index.
27

Investigation of the effect of agricultural spray application equipment on damage to entomopathogenic nematodes a biological pest control agent /

Fife, Jane Patterson, January 2003 (has links)
Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xxii, 303 p.: ill. (some col.). Includes abstract and vita. Advisors: H. Erdal Ozkan and Richard C. Derksen, Dept. of Food, Agricultural, and Biological Engineering. Includes bibliographical references (p. 213-221).
28

Characterization and molecular cloning of proteinases of Trichinella spiralis (Nematoda) /

Lun, Hoi-man. January 2001 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 98-115).
29

Threshold chemosensitivity of the nematode caenorhabditis elegans

Terrill, William Forrest 05 1900 (has links)
No description available.
30

Analysis of cytochromes in developmental stages of Caenorhabditis Elegans

Eisenstein, Aaron 05 1900 (has links)
No description available.

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