The Application of Fluorescent Nanocrystals to Study the Distribution of Neuropeptides in the Aedes Aegypti Mosquito

Semiconductor nanocrystals, also known as quantum dots (QDs), have been used in studies involving mice and human tissues, but never before in research on insects. We used QDs to study the distribution of two neuropeptides in the Aedes aegypti mosquito, the vector of both dengue and yellow fever. These neuropeptides play a significant role in the production of juvenile hormone, a hormone that controls biting behavior, metamorphosis, and reproduction throughout the life of the mosquito. The two neuropeptides allatostatin-C (AS-C) and allatotropin (AT) function as inhibitory (AS-C) and stimulatory (AT) regulators of juvenile hormone synthesis in the corpus allatum gland. In other insects, they also affect heart rate, gut movement, and nutrient uptake. Conjugating these neuropeptides to quantum dots via a streptavidinlbiotin link, we were able to expose the mosquito corpus allatum and abdomen to allatostatin-C and allatotropin and then to visualize their distribution under UV light using confocal and compound light microscopy. Histological sections of the whole mosquito, incubations of tissues with conjugates (in vitro), and microinjections of conjugates into the mosquito (in vivo) were performed. The results showed that quantum dots can be used to detect neuropeptide distribution in the mosquito. The more we understand about these neuropeptides and juvenile hormone, the more we can contribute to stopping the spread of infectious diseases, such as dengue and yellow fever.

Characterization of Juvenile Hormone Biosynthetic Enzymes in the Mosquito, Aedes aegypti

The juvenile hormones (JHs) are sesquiterpenoid compounds that play a central role in insect reproduction, development and behavior. They are synthesized and secreted by a pair of small endocrine glands, the corpora allata (CA), which are intimately connected to the brain. The enzymes involved in the biosynthesis of JH are attractive targets for the control of mosquito populations. This dissertation is a comprehensive functional study of five Aedes aegypti CA enzymes, HMG-CoA synthase (AaHMGS), mevalonate kinase (AaMK), phosphomevalonate kinase (AaPMK), farnesyl diphosphate synthase (AaFPPS) and farnesyl pyrophosphate phosphatase (AaFPPase). The enzyme AaHMGS catalyzes the condensation of acetoacetyl-CoA and acetyl-CoA to produce HMG-CoA. The enzyme does not require any co-factor, although its activity is enhanced by addition of Mg2+. The enzyme AaMK is a class I mevalonate kinase that catalyzes the ATP-dependent phosphorylation of mevalonic acid to form mevalonate 5-phosphate. Activity of AaMK is inhibited by isoprenoids. The enzyme AaPMK catalyzes the cation-dependent reversible reaction of phosphomevalonate and ATP to form diphosphate mevalonate and ADP. The enzyme AaFPPS catalyzes the condensation of isopentenyl diphosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) to form geranyl diphosphate (GPP) and farnesyl pyrophosphate (FPP). The enzyme AaFPPS shows an unusual product regulation mechanism, with chain length final product of 10 or 15 C depending on the metal cofactor present. The enzymes AaFPPase-1 and AaFPPase-2 efficiently hydrolyze FPP into farnesol, although RNAi experiments demonstrate that only AaFPPase-1 is involved in the catalysis of FPP into FOL in the CA of A. aegypti. This dissertation also explored the inhibition of the activity of some of the JH biosynthesis enzymes as tools for insect control. We described the effect of N-acetyl-S-geranylgeranyl-L-cysteine as a potent inhibitor of AaFPPase 1 and AaFPPase-2. In addition, inhibitors of AaMK and AaHMGS were also investigated using purified recombinant proteins. The present study provides an important contribution to the characterization of recombinant proteins, the analysis of enzyme kinetics and inhibition constants, as well as the understanding of the importance of these five enzymes in the control of JH biosynthesis rates.

Atividades biológicas de extratos salinos de sementes de plantas da caatinga contra Aedes Aegypti e investigação da participação de proteínas bioativas

Dengue fever, currently the most important arbovirus, is transmitted by the bite of the Aedes aegypti mosquito. Given the absence of a prophylactic vaccine, the disease can only be controlled by combating the vector insect. However, increasing reports of resistance and environmental damage caused by insecticides have led to the urgent search for new safer alternatives. Twenty - um plant s eed extracts from the Caatinga were prepared , tested and characterized . Sodium phosphate ( 50 mM pH 8.0) was used as extractor. All extracts showed larvicidal and ovipositional deterrence activity . Extracts of D. grandiflora, E. contortisiliquum, A. cearenses , C. ferrea and C. retusa were able to attract females for posture when in low co ncentration . In the attractive concentrations, the CE of E. contortisiliquum and A. cearenses were able to kill 52% and 100% of the larvae respectively . The extracts of A. cearenses , P. viridiflora, E. velutina, M. urundeuva and S. brasiliensis were also pupicides, while extracts of P. viridiflora, E. velutina, E. contortisiliquum , A. cearenses, A. colubrina, D. grandiflora , B. cheilantha , S. spectabilis, C. pyramidalis, M. regnelli e G. americana displayed adulticidal activity. All extracts were toxic to C. dubia zooplankton . The EB of E. velutina and E. contortisiliquum did not affect the viability of fibroblasts . In all extracts were identified at least two potential insecticidal proteins such as enzyme inhibitors, lectins and chitin - binding proteins and components of secondary metabolism . Considering all bioassays , the extracts from A. cearenses, P. viridiflora, E. contortisiliquum , S. brasiliensis, E. velutina and M. urundeuva were considered the most promising . The E. contortisiliquum extracts was the only one who did not show pupicida activity, indicating that its mechanism of action larvicide and adulticidal is related only to the ingesti on of toxic compounds by insect , so it was selected to be fragmenting. As observed for the CE , th e protein fractions of E. contortisiliquum also showed larvicidal activity, highlighting that F2 showed higher larvicidal activity and lower en vironmental toxicity than the CE source. The reduction in the proteolytic activity of larvae fed with crude extra ct and fractions of E. contortisiliquum suggest ed that the trypsin inhibitors ( ITEc) would be resp onsible for larvicidal activity . However the increase in the purification of this inhibitor resulted in loss of larvicidal activity , but the absence of trypsin inhibitor reduced the effectiveness of the fractions , indicating that the ITEC contributes to the larvicidal activity of this extract. Not been observed larvicidal activity and adulticide in rich fraction vicilin, nor evidence of the contribution o f this molecule for the larvicidal activity of the extract. The results show the potential of seeds from plant extracts of Caatinga as a source of active molecules against insects A. aegypti at different stages of its development cycle, since they are comp osed of different active compounds, including protein nature, which act on different mechanisms should result in the death of insec

Exploring Relationships Between Vector-Borne Diseases and Landscape Architecture: Aedes aegypti, Aedes albopictus and Landscape Architecture

Thesis (Master's)--University of Washington, 2016-06

Un modelo tipo predador - presa para la dinámica de población del mosquito Aedes aegypti con control químico y control biológico

Según la Organización Mundial de la Salud (OMS, 2000) la fiebre por dengue y la fiebre hemorrágica 1 por dengue son un problema de salud pública a las cuales dos quintas partes de la población mundial se encuentran en riesgo. Las principales medidas de prevención y control han sido la fumigación masiva de insecticidas dirigida contra los mosquitos adultos (adulticidas) y la aplicación de larvicidas (control químico). Sin embargo, a pesar de que dichas medidas reducen rápidamente la población de mosquitos adultos y eliminan un 90% de la población de larvas en un criadero, su efecto es sólo transitorio pues no afectan la generación de nuevos mosquitos. En efecto, los registros estadísticos demuestran un avance del mosquito a pesar de las campañas de fumigación y aplicación de larvicidas (OMS, 2000). Por otra parte Hernández y García (2000) señalan que hay factores negativos asociados con el control químico de las poblaciones de mosquitos.

Detection of all four dengue serotypes in Aedes aegypti female mosquitoes collected in a rural area in Colombia

The Aedes aegypti vector for dengue virus (DENV) has been reported in urban and periurban areas. The information about DENV circulation in mosquitoes in Colombian rural areas is limited, so we aimed to evaluate the presence of DENV in Ae. aegypti females caught in rural locations of two Colombian municipalities, Anapoima and La Mesa. Mosquitoes from 497 rural households in 44 different rural settlements were collected. Pools of about 20 Ae. aegypti females were processed for DENV serotype detection. DENV in mosquitoes was detected in 74% of the analysed settlements with a pool positivity rate of 62%. The estimated individual mosquito infection rate was 4.12% and the minimum infection rate was 33.3/1,000 mosquitoes. All four serotypes were detected; the most frequent being DENV-2 (50%) and DENV-1 (35%). Two-three serotypes were detected simultaneously in separate pools. This is the first report on the co-occurrence of natural DENV infection of mosquitoes in Colombian rural areas. The findings are important for understanding dengue transmission and planning control strategies. A potential latent virus reservoir in rural areas could spill over to urban areas during population movements. Detecting DENV in wild-caught adult mosquitoes should be included in the development of dengue epidemic forecasting models.

Spatial and temporal country-wide survey of temephos resistance in Brazilian populations of Aedes aegypti

The organophosphate temephos has been the main insecticide used against larvae of the dengue and yellow fever mosquito ( Aedes aegypti ) in Brazil since the mid-1980s. Reports of resistance date back to 1995; however, no systematic reports of widespread temephos resistance have occurred to date. As resistance investigation is paramount for strategic decision-making by health officials, our objective here was to investigate the spatial and temporal spread of temephos resistance in Ae. aegypti in Brazil for the last 12 years using discriminating temephos concentrations and the bioassay protocols of the World Health Organization. The mortality results obtained were subjected to spatial analysis for distance interpolation using semi-variance models to generate maps that depict the spread of temephos resistance in Brazil since 1999. The problem has been expanding. Since 2002-2003, approximately half the country has exhibited mosquito populations resistant to temephos. The frequency of temephos resistance and, likely, control failures, which start when the insecticide mortality level drops below 80%, has increased even further since 2004. Few parts of Brazil are able to achieve the target 80% efficacy threshold by 2010/2011, resulting in a significant risk of control failure by temephos in most of the country. The widespread resistance to temephos in Brazilian Ae. aegypti populations greatly compromise effective mosquito control efforts using this insecticide and indicates the urgent need to identify alternative insecticides aided by the preventive elimination of potential mosquito breeding sites.

FOLHA da Embrapa: Embrapa declara guerra ao Aedes aegypti.

2016

Aedes aegypti Pharate First Instar Aseasonal Quiescence Cues Anticipatory Plasticity with Implications for Urban Vector Ecology and Control

The eggs of the dengue fever vector Aedes aegypti possess the ability to undergo an extended quiescence period hosting a fully developed first instar larvae within its chorion. As a result of this life history stage, pharate larvae can withstand months of dormancy inside the egg where they depend on stored reserves of maternal origin. This adaptation known as pharate first instar quiescence, allows A. aegypti to cope with fluctuations in water availability. An examination of this fundamental adaptation has shown that there are trade-offs associated with it. Aedes aegypti mosquitoes are frequently associated with urban habitats that may contain metal pollution. My research has demonstrated that the duration of this quiescence and the extent of nutritional depletion associated with it affects the physiology and survival of larvae that hatch in a suboptimal habitat; nutrient reserves decrease during pharate first instar quiescence and alter subsequent larval and adult fitness. The duration of quiescence compromises metal tolerance physiology and is coupled to a decrease in metallothionein mRNA levels. My findings also indicate that even low levels of environmentally relevant larval metal stress alter the parameters that determine vector capacity. My research has also demonstrated that extended pharate first instar quiescence can elicit a plastic response resulting in an adult phenotype distinct from adults reared from short quiescence eggs. Extended pharate first instar quiescence affects the performance and reproductive fitness of the adult female mosquito as well as the nutritional status of its progeny via maternal effects in an adaptive manner, i.e., anticipatory phenotypic plasticity results as a consequence of the duration of pharate first instar quiescence and alternative phenotypes may exist for this mosquito with quiescence serving as a cue possibly signaling the environmental conditions that follow a dry period. M findings may explain, in part, A. aegypti’s success as a vector and its geographic distribution and have implications for its vector capacity and control.

GEOTECNOLOGIAS APLICADA AO MONITORAMENTO DO VETOR AEDES AEGYPTI NA ÁREA ITAQUI-BACANGA, SÃO LUIS - MA.

O uso do SIG na espacialização de dados referentes à saúde é de extrema importância para o monitoramento das variáveis relacionadas à doença em questão, como por exemplo, fatores físicos, sociais e variantes relacionadas ao vetor transmissor. Esta geotecnologia possui uma linguagem computacional, na qual é possível armazenar, cruzar e relacionar dados, através da localização de pontos na superfície terrestre. No Brasil, a problemática da dengue, diante do seu agravamento e a iminência de uma epidemia de proporções consideráveis, tem intensificado as pesquisas para o desenvolvimento de métodos mais eficazes para o controle dessa doença no ambiente urbano. Em nível local, a utilização de SIGs para o monitoramento da dengue no município de São Luís, contribuiu para uma análise da distribuição espacial da doença na cidade. Deste modo, esta pesquisa objetivou analisar o problema da dengue na referida localidade, utilizando as geotecnologias e a educação ambiental sinergicamente associadas, como estratégia para que a comunidade descobrisse, através da participação nas atividades da pesquisa, a dimensão do problema da dengue no seu próprio habitat.

Orientações para a visita domiciliar do ACS voltada para eliminação do Aedes Aegypti

A webpalestra é uma parceria entre o Telessaúde SC, a Diretoria de Vigilância Epidemiológica e a Gerência de Coordenação de Atenção Básica da Secretaria de Estado da Saúde, e tem o objetivo de capacitar os profissionais ACS para realização das visitas domiciliares voltadas para identificação e orientação para eliminação do Aedes Aegypti. Os palestrantes fazem um panorama geral da situação brasileira e catarinense das infecções transmitidas pelo vetor e orientam os ACS de como inserir na sua rotina as atividades relacionadas à eliminação do mosquito.

Atualização no combate vetorial ao Aedes Aegypti: boas-vindas

Vídeo de boas-vindas do curso de Atualização no combate vetorial ao Aedes aegypti, desenvolvido pelo TelessaúdeRS/UFRGS em parceria com o Ministério da Saúde. Voltado principalmente para agentes comunitários de saúde, agentes de combate às endemias e militares, o curso reúne informações básicas sobre o mosquito Aedes, as doenças que transmite, e as medidas necessárias para combater sua proliferação no Brasil.

Atualização no combate vetorial ao Aedes Aegypti: mensagem para agentes de combate às endemias e militares

Vídeo dirigido aos agentes de combate às endemias e militares com vistas à participação no curso Atualização no combate Vetorial ao Aedes aegypti. Desenvolvido pelo TelessaúdeRS/UFRGS em parceria com o Ministério da Saúde, o curso aborda aspectos gerais e práticas de combate ao mosquito que transmite, entre outras doenças, Dengue, Chikungunya e Zika Vírus.

Atualização no combate Vetorial ao Aedes aegypti: apresentação

Vídeo de apresentação do curso "Atualização no combate Vetorial ao Aedes aegypti" desenvolvido pelo TelessaúdeRS/UFRGS em parceria com o Ministério da Saúde. O curso visa desenvolver ou aprofundar conhecimentos e habilidades nos alunos para identificação e combate ao mosquito que transmite, entre outras doenças, Dengue, Chikungunya e Zika Vírus.

Atualização no combate vetorial ao Aedes Aegypti: a importância do ACS na campanha nacional contra o mosquito Aedes

Vídeo do curso EaD de "Atualização no combate Vetorial ao Aedes aegypti", desenvolvido pelo TelessaúdeRS/UFRGS em parceria com o Ministério da Saúde Trata da importância da participação do agente comunitário de saúde na campanha nacional de combate ao mosquito Aedes. O vídeo traz um depoimento de um agente comunitário da saúde de Dom Feliciano, município localizado no Rio Grande do Sul, sobre as ações locais realizadas para o combate ao mosquito transmissor da Dengue, Chikungunya e Zika Vírus, entre outras doenças.