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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.
71

Caracterização morfo-histoquímica de tecidos do sistema digestório de larvas de Aedes aegypti / Morpho-histochemical description of the tissues of the digestive system of Aedes aegypti larvae

Lemos, Alessandra Bittencourt de January 2016 (has links)
Muitos trabalhos são desenvolvidos para identificar substâncias ou microrganismos capazes de controlar a população de insetos importantes para a saúde pública, sendo a identificação de lesões histológicas um critério para compreender o mecanismo de ação e eficácia do produto. As análises histopatológicas são baseadas na comparação entre tecidos de indivíduos controle e indivíduos expostos. Entretanto, são raros os trabalhos que referenciam o estado dos tecidos sadios. Neste trabalho caracterizou-se morfo-histoquimicamente os principais tecidos sadios do sistema digestório de larvas em 3º a 4º ínstar de Aedes aegypti, mostrando diversas imagens das variações que podem ser esperadas, além de apresentar as técnicas de processamento. Para isto, um total de trinta larvas foram fixadas, desidratadas e incluídas em historesina. Cortes foram realizados e corados com HE para morfologia e azul do Nilo, azul bromofenol, azul de toluidina e PAS para a caracterização histoquímica. Como resultados, o intestino das larvas se mostrou um tubo reto, formado por uma camada simples de células cúbicas, moderadamente acidófilas, com núcleo central e uma borda em escova voltada para o lúmen. Foram registradas variações celulares, uma vez que as células epiteliais também são secretivas das enzimas digestivas. Cortes sequenciais foram importantes para definir a morfologia, uma vez que o ângulo e altura de corte podem influenciar na sua aparência. O PAS revelou a presença de muitos grânulos de glicogênio por todos os tecidos, inclusive nas vesículas secretivas. Estas ainda possuem muitas proteínas e foram coradas fracamente para lipídios. Não foram registrados eventos de metacromasia na cor vermelha com o azul de toluidina, entretanto os tecidos parecem se corar diferentemente do tegumento. / Many surveys are designed to identify substances or microorganisms capable of controlling the population of insects that are important to public health, and the identification of resulting histological injures is a criterion for understanding the mechanism of action and the efficacy of the product. The histopathological analyses are based on the comparison between tissues of control subjects and exposed subjects, but there are rare studies that mention the state of healthy tissues. This work characterized the main morpho-histochemically healthy tissues of the digestive system of larvae in the 3rd and the 4th instar of Aedes aegypti, showing several images of the variations that can be expected, as well as displaying processing techniques. For this, a total of thirty larvae were pinned, dehydrated and embedded in historesin. Sections were made and stained with hematoxylin for morphology and Blue Nile, bromophenol blue, toluidine blue and PAS staining for the immunohistochemical characterization. As a result, the intestines of the larvae showed an upright tube formed by a single layer of cuboidal cells, moderately acidophilic, with a central nucleus and a brush border facing the lumen. Cellular changes were recorded, since epithelial cells also secrete digestive enzymes. Sequential slices were important in defining the morphology, since the angle and height of the cut may affect its appearance. The PAS revealed the presence of many glycogen granules in all tissues, including the secretory vesicles. These still have protein and were weakly colored to lipids. There were no metachromasia events in red with toluidine blue, though the tissues seem to blush differently from the integument.
72

Síntese de novas tiazolidin-4-onas bioativas

MENDES, Carlos Henrique da Silva 27 July 2017 (has links)
Submitted by Fernanda Rodrigues de Lima (fernanda.rlima@ufpe.br) on 2018-08-20T20:44:22Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Carlos Henrique da Silva Mendes.pdf: 1899622 bytes, checksum: 512f3432ea90f44f16e29fc08da2b746 (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-08-28T18:10:53Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Carlos Henrique da Silva Mendes.pdf: 1899622 bytes, checksum: 512f3432ea90f44f16e29fc08da2b746 (MD5) / Made available in DSpace on 2018-08-28T18:10:53Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Carlos Henrique da Silva Mendes.pdf: 1899622 bytes, checksum: 512f3432ea90f44f16e29fc08da2b746 (MD5) Previous issue date: 2017-07-27 / Dentre os compostos que apresentam atividade biológica relevante, os heterocíclicos apresentam um importante papel, principalmente os que possuem o anel de cinco membros. O grupo heterocíclico das Tiazolidin-4-onas tem sido estudado por apresentar plurifuncionalidades que podem ser exploradas. No presente trabalho, propõe-se sintetizar e estudar a atividade biológica (Leishmanicida e Larvicida) de 20 inéditas Tiazolidin-4onas (CH01-20). As moléculas foram sintetizadas de forma a se observar a contribuição lipofílica e do efeito indutivo dos substituintes. Para a verificação da atividade Leishmanicida, os compostos foram testados em diferentes concentrações frente à forma promastigota da Leishmania amazonensis, utilizando como controle positivo a Anfotericina. Já para o estudo da atividade larvicida, as tiazolidin-4-onas foram testadas frente a larvas do Aedes aegypti no estágio L4. Foi observado, na atividade leishmanicida, que sete compostos sintetizados apresentaram índice de seletividade maior que o controle positivo. Dentre esses, cinco apresentaram valor de IC₅₀ equiparáveis ao padrão e uma CH18 apresentou valor de IC50 de 0,96 μM, que é equivalente a anfotericina 1,0 μM. O composto CH19 apresentou o melhor índice de seletividade (34,93), que foi cerca de cinco vezes maior que o padrão (7,5). Quanto a atividade larvicida nenhuma das moléculas testadas foi ativa. / Among the components and human activity, heterocyclics play an important role, especially those with the five-membered ring. The heterocyclic group of Thiazolidines-4-ones has been studied because it presents multi-functionalities that can be explored. In the present work, it is proposed to synthesize and study the biological activity (Leishmanicide and Larvicide) of 20 unpublished thiazolidin-4ones (CH01-20). The molecules were synthesized in order to observe the lipophilic contribution and the inductive effect of the substituents. For a verification of the Leishmanicidal activity, the compounds thus tested in different concentrations against the promastigote form of Leishmania amazonensis, using as a positive control Amphotericin. For the study of larvicidal activity, such as thiazolidin-4-ones were tested against Aedes aegypti larvae in the L4 stage. It was observed in the leishmanicidal activity that seven synthesized compounds showed a selectivity index greater than the positive control. Among these, five had an IC50 value comparable to the standard and one CH18 presented an IC 50 value of 0.96 μM, which is equivalent to 1.0 μM amphotericin. Compound CH19 had the best selectivity index (34.93), which was about five times higher than the standard (7.5). As for the larvicidal activity of the molecules tested for active.
73

Avaliaçao de um biolarvicida à base de Bacillus thuringiensis sorovar. israelensis, desenvolvido no Brasil, para o controle do Aedes aegypti (Diptera:Culicidae)

Paula de Araújo, Ana January 2006 (has links)
Made available in DSpace on 2014-06-12T15:04:29Z (GMT). No. of bitstreams: 2 arquivo1754_1.pdf: 774898 bytes, checksum: 529ec44b21ee9797ffdf63d5f699fc8b (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2006 / Neste trabalho foram determinados a atividade tóxica e o desempenho em campo simulado de um larvicida experimental à base de Bacillus thuringiensis israelensis contra larvas de Aedes aegypti. Diferentes lotes de produção de pó técnico (PT) pré-formulado, foram avaliados em bioensaios, para definição das concentrações que eliminam 50% (CL50) das larvas e definição da potência do produto. Um dos lotes foi submetido a diferentes doses de radiação gama para a inativação dos esporos, sendo avaliado quanto à viabilidade microbiológica e toxicidade. As apresentações em comprimido (C) contendo 15% de princípio ativo, em PT e em pó técnico irradiado (PTI) foram testadas nas concentrações de 250 mg/50L de água, em recipientes plásticos, em condições simuladas de campo (TCS). A eficácia inicial do produto foi estimada pela mortalidade de 50 L4 de Ae. aegypti, após 48 h de exposição, e a persistência, mortalidade observada ao longo do tempo, pela introdução periódica de 50 L1 e recuperação de pupas. Os recipientes foram submetidos às seguintes variáveis: exposição solar ou sombra, renovação de 20% ou 60% do volume da água periodicamente, e a diferentes freqüências de colonização. Amostras de água foram coletadas para a verificação de esporos viáveis (UFC/ml) nos recipientes tratados. Os resultados demonstraram que existem diferentes níveis de toxicidade entre os lotes avaliados em laboratório, mas que estas diferenças não comprometem a atividade larvicida do produto em TCS. A CL50 média foi estimada em 0,26 ± 0,1 mg/L, com potência de 750 UTI/mg. A dose de 20 KGy de radiação gama inativou o maior percentual de esporos (99,9%) com menor perda da toxicidade. Em TCS, PTI, PT e C promoveram de 90 a 100% de mortalidade inicial e controle total durante 6 meses, na sombra. Não houve diferenças entre recipientes que sofreram ou não reposição de água, nem entre aqueles colonizados com diferentes números de larvas. A densidade de larvas também não influenciou a concentração de esporos ao longo do experimento. Nos recipientes tratados com PTI as concentrações de esporos viáveis foram inferiores às observadas para o PT em todas as coletas. A exposição solar foi o único fator que limitou o tempo de persistência do produto nos recipientes. Concluímos que o produto avaliado apresenta boa qualidade de produção com níveis altos de toxicidade e excelente persistência
74

The genetic control of Aedes aegypti

Haghighat-Khah, Roya Elaine January 2014 (has links)
No description available.
75

An ultrastructural study of the anal papillae of aedes campestris larvae and of the hind gut of Aedes campestris and Aedes aegypti larvae

Meredith, Joan January 1971 (has links)
The basic morphology and ultrastructure of the anal papillae of a saline water mosquito larva (Aedes campestris) have been investigated under two physiological conditions: (a) normal hyperosmotic external medium and (b) dilute hyposmotic medium. The ultrastructure of these organs suggests that they are not rudimentary, but rather are made up of cells that are morphologically specialized for transport. The anal papillae appear active in both the normal and dilute media and possible functions under the two physiological conditions are discussed. No major qualitative or quantitative differences were observed with the large change in external medium. This suggests that physiologically-demonstrated adaptive changes may require only minor structural alterations. The morphology and ultrastructure of the hind gut of A. campestris larvae were compared under two physiological conditions; normal (requiring hyporegulation) and dilute (requiring hyperegulation) external medium. No differences which might be associated with hyporegulation were observed. The rectum of A. campestri s was compared to that of Aedes aegypti. The rectum in the former is composed of two regions, an anterior and posterior rectum, while in Aedes aegypti, an exclusively freshwater mosquito larva, the rectum has only a single region. The rectal epithelia in both insects studied have morphological specializations for water and ion transport, and a consideration of quantative differences suggests that the posterior rectum is unique to Aedes campestris and hence could be responsible for the ability of this species to produce hyperosmotic urine. When the posterior rectal epithelium is compared to similar transporting epithelia in previously-studied terrestrial insects, several ultra-structural differences were noted. It is suggested that the mechanism of hyperosmotic urine production in saline water insects may be different from that in terrestrial insects. Several possible mechanisms of hyperosmotic urine production are discussed. / Science, Faculty of / Zoology, Department of / Graduate
76

Avaliação do potencial de óleo essencial de sementes de Syagrus coronata (Martius) Beccari (Arecaceae: Arecoideae) para controle do Aedes aegypti

SANTOS, Leilane Marina Morais dos 21 July 2016 (has links)
Submitted by Pedro Barros (pedro.silvabarros@ufpe.br) on 2018-09-24T22:09:12Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Leilane Marina Morais dos Santos.pdf: 1545888 bytes, checksum: 8c26f4a65db21292b99ca0959f635b08 (MD5) / Approved for entry into archive by Alice Araujo (alice.caraujo@ufpe.br) on 2018-09-25T17:18:13Z (GMT) No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Leilane Marina Morais dos Santos.pdf: 1545888 bytes, checksum: 8c26f4a65db21292b99ca0959f635b08 (MD5) / Made available in DSpace on 2018-09-25T17:18:13Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Leilane Marina Morais dos Santos.pdf: 1545888 bytes, checksum: 8c26f4a65db21292b99ca0959f635b08 (MD5) Previous issue date: 2016-07-21 / FACEPE / O mosquito Aedes aegypti é vetor dos agentes causadores da dengue, chikungunya, febre amarela e febre do vírus zika, doenças que apresentam grande impacto a nível mundial. Atualmente, há vacina disponível apenas contra a febre amarela. Dessa forma, as principais alternativas para controle das demais doenças são as estratégias de controle químico e biológico da população do vetor, e o uso de repelente visando à prevenção da picada do mosquito. Diversos compostos sintéticos têm sido utilizados para controlar populações de A. aegypti; contudo, esses inseticidas têm se mostrado danosos ao meio ambiente e à saúde humana. Adicionalmente, existem diversos relatos de populações do mosquito resistente a esses inseticidas. Moléculas de origem natural têm sido investigadas como alternativas para substituição desses inseticidas, já que são biodegradáveis geralmente causam menor impacto ambiental. Os óleos essenciais são misturas complexas formadas pelo metabolismo secundário de algumas plantas. As propriedades inseticidas de óleos essenciais têm sido descritas em vários estudos, inclusive contra A. aegypti. Syagrus coronata (ouricuri) é uma planta de importância econômica, presente na região semiárida do Nordeste brasileiro. A presente dissertação avaliou o potencial do óleo essencial extraído de sementes de S. coronata para o controle de Aedes aegypti. O óleo foi extraído por meio da técnica de hidrodestilação e caracterizado por cromatografia gasosa acoplada à espectrometria de massas (GC-MS). O óleo essencial foi avaliado quanto às atividades larvicida e ovicida; e quanto à influência sobre a escolha do sítio de oviposição. Foi investigado também o efeito do óleo sobre a natação das larvas, em condições sub-letais. A atividade larvicida e o efeito sobre a oviposição do ácido octanóico (um dos componentes majoritários) foram determinados. A extração do óleo apresentou um rendimento de 0,41% e a análise por GC-MS revelou que 98,42% da composição do óleo corresponderam aos seguintes ácidos graxos: ácido octanóico (40,55%), ácido decanóico (17,39%) e ácido dodecanóico (40,48%). O óleo de sementes de S. coronata promoveu a morte de larvas de A. aegypti, com CL50 de 21,07 ppm (48 horas de exposição), mas não apresentou ação ovicida. Os ácidos octanóico, decanóico e dodecanóico apresentaram atividade larvicida com CL₅₀ de 51,78 ppm 24.01 and 19.72 ppm, respectivamente. No teste de natação, não foram observadas diferenças significativas nas distâncias percorridas por larvas incubadas durante 30 minutos ou 24 horas com o óleo e por larvas do grupo controle. O óleo de S. coronata (50 ppm) apresentou efeito deterrente sobre a oviposição, assim como o ácido octanóico na mesma concentração. Na literatura, é descrito que o ácido decanóico também apresenta efeito deterrente, enquanto o ácido dodecanóico tem efeito estimulante sobre a oviposição. Em conclusão, o óleo essencial de sementes de S. coronata foi capaz de promover morte de larvas de A. aegypti e exercer efeito deterrente sobre as fêmeas grávidas. A atividade larvicida está relacionada a um efeito sinérgico entre os componentes do óleo e o efeito deterrente de oviposição está provavelmente ligado à presença dos ácidos octanóico e decanóico, que correspondem a 57,94% da composição do óleo extraído. / The Aedes aegypti mosquito is the vector of the causative agents of dengue, chikungunya, yellow fever and zika fever, diseases that have a great impact worldwide. Currently, vaccine is available only against yellow fever. Thus, the main alternatives for control of the other diseases are chemical and biological strategies for control of the vector population and the use of repellent for the prevention of mosquito bites. Several synthetic compounds have been used to control A. aegypti populations; however, these insecticides have been shown to be harmful to the environment and human health. Additionally, there are several reports of mosquito populations resistant to these insecticides. Molecules of natural origin have been investigated as alternatives to replace these pesticides, since they are biodegradable and generally cause less environmental impact. Essential oils are complex mixtures formed by the secondary metabolism of some plants. The insecticidal properties of essential oils have been described in several studies, including against A. aegypti. Syagrus coronata (ouricuri) is a plant with economic importance, present in the semiarid region of Northeast, Brazil. This work evaluated the potential of the essential oil extracted from S. coronata seeds for the control of A. aegypti. The oil was extracted by hydrodistillation technique and characterized by gas chromatography-mass spectrometry (GC-MS). The essential oil was evaluated for larvicidal and ovicidal activities, as well as for influence on the choice of oviposition site. It was also investigated the effect of the oil on the swimming activity of larvae in sub-lethal conditions. The larvicidal activity and the effect on oviposition of the octanoic acid (one of the major components) were determined. The oil extraction showed a yield of 0.41% and GC-MS revealed that 98.42% of the oil composition corresponded to the following fatty acids: octanoic acid (40.55%), decanoic acid (17.39 %) and dodecanoic acid (40.48%). S. coronata seed oil promoted the killing of A. aegypti larvae, with LC50 of 21.07 ppm (48-h exposure), but had no ovicidal action. The octanoic, decanoid and dodecanoic acids showed larvicidal activity with LC₅₀ of 51.78, 24.01 and 19.72 ppm, respectively. This result indicates that other compounds present in the oil are also responsible for the larvicidal effect. In the swimming test, no significant differences were observed in the distances covered by larvae incubated for 30 min or 24 h with the oil and larvae from the control group. The S. coronata oil and the octanoic acid (both at 50 ppm) showed a deterrent effect on oviposition. In the literature, it is described that the decanoic acid also has a deterrent effect while the dodecanoic acid has a stimulant effect on oviposition. In conclusion, the essential oil of S. coronata seed was able to promote death of larvae of A. aegypti and exerted a deterrent effect on pregnant females. The larvicidal activity is related to a synergistic effect between oil components and the oviposition deterrent effect is probably linked to the presence of octanoic and decanoic acid, which correspond to 57.94% of the oil composition.
77

Plagiorchis elegans from cercariae to infective metacercariae : factors affecting transmission, requirements for development, and behavioural responses of intermediate hosts to infection

Lowenberger, Carl A. (Carl Arnold) January 1993 (has links)
No description available.
78

Effects of substrate characteristics on the vertical distribution of fourth instar larvae of Aedes aegypti (Diptera:Culicidae)

Paul, Robert H. January 1994 (has links)
No description available.
79

The influence of phenylthiourea on encapsulation, melanization and survival in larvae of the mosquito, Aedes aegypti, parasitized by the nematode, Neoaplectana carpocapsae.

Beresky, Michael A. 01 January 1974 (has links) (PDF)
No description available.
80

Genetic factors affecting the RNA interference pathway of Aedes aegypti mosquitoes

Haac, Mary Etna Richter 30 December 2013 (has links)
Aedes aegypti mosquitoes are the vectors of many significant arboviruses that cause tremendous social and economic impact. RNA interference (RNAi) plays a crucial role in the vector competence of mosquitoes and is often targeted in studies involving mosquito innate immunity, genetics-based vector control strategies, and the development of viral-resistant transgenic mosquitoes. In general, RNA interference is induced by double stranded RNA (dsRNA) and results in the inhibition of cognate gene expression. There are several different RNA interference pathways, with distinct functions and mechanisms. The micro RNA pathway is important for endogenous gene regulation and development. The endogenous small interfering RNA (endo-siRNA) pathway functions in gene regulation and protection of the genome from the deleterious effects of transposable elements. The exogenous siRNA (exosiRNA) pathway is a major contributor to mosquito innate immunity and vector competence by limiting viral replication during infection. Lastly, the piwi RNA (piRNA) pathway primarily functions in protecting the genome from the deleterious effects of transposable elements. While the structure and function of many genes involved in Drosophila RNAi have been characterized, the corresponding mosquito orthologs have only been peripherally described or remain unknown. Thus, the overall purpose of this study is to improve the understanding of mosquito RNAi mechanisms by identifying and analyzing genetic factors involved in the various pathways. This research especially focuses on characterizing and analyzing putative doubleiii stranded RNA binding proteins (dsRBPs) important to the function of the RNAi initiator and effector complexes. Two genes, r2d2 and r3d1 are orthologs of Drosophila genes known to have important roles in the RNAi initiator complex. A third member of the same family, which we refer to as extra loquacious (exloqs), appears to have no known orthologs outside of the Aedes genus. Structural characterization of these genes included identification of single nucleotide polymorphisms (SNPs), novel exons and alternative splice variants. RT-PCR assays were utilized to examine differential expression of all three genes in specific tissues and developmental stages. Sub-cellular fractionation assays enabled intracellular localization of the RNAi proteins within Ae. aegypti cells. Co-immunoprecipitation of tagged dsRBPs revealed protein-protein interactions between specific dsRBPs and known RNAi factors. In addition, an exo-siRNA sensor was designed and tested in-vivo and in-vitro with the purpose of facilitating the identification of novel genetic factors involved in this anti-viral pathway. Lastly, TALENbased gene disruption was successfully employed to knockout the exloqs gene in Ae. aegypti mosquitoes, enabling further analysis into the function of this gene. The research described in this document provides further insight into mosquito innate immunity and gene regulation, which is important to the advancement of genetics-based vector control strategies. / Ph. D.

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