Plasmodium vivax: gametócitos e estratégias para o bloqueio de transmissão: Plasmodium vivax: gametocytes and strategies to block transmission

A malária é uma doença causada por parasitas do gênero Plasmodium. Considerada um grave problema de saúde pública, a malária está presente em diversos países tropicais e subtropicais, colocando em risco mais da metade da população mundial. Plasmodium vivax é uma das espécies causadoras da malária ao homem e é a das que apresenta maior distribuição geográfica no mundo e, devido a seus aspectos biológicos, tem se tornado um grande desafio em meio a um cenário de eliminação. Os gametócitos são as formas responsáveis pela transmissão do Plasmodium ao vetor, as fêmeas do mosquito Anopheles. Avanços nos estudos da biologia e dinâmica dos gametócitos em P. falciparum, se tornaram possíveis após o estabelecimento de um sistema de cultivo in vitro e modelos experimentais. No entanto, a ausência dessas metodologias para P. vivax tem dificultado o avanço nas pesquisas. Atualmente, diversos estudos e programas tem focado na eliminação da malária e, para alcançar esse sucesso é necessário um conhecimento e compreensão dos estágios envolvidos na transmissão, como os gametócitos. Aqui apresentamos os principais avanços no estudo de gametócitos de P. vivax novas perspectivas no desenvolvimento das ferramentas necessárias para a investigação de agentes para bloquear a transmissão

O Microscópio de Força Atômica (AFM): importante ferramenta no estudo da morfologia de superfícies na escala nanométrica

O surgimento do Microscópio de Força Atômica (AFM) promoveu um grande impacto na Ciência, de uma forma geral, devido a sua capacidade de gerar imagens com resolução atômica, proporcionando o estudo da morfologia de superfícies, condutoras ou não, em escala nanométrica. Além disso, o AFM não exige uma preparação prévia das amostras a serem estudadas, possuindo apenas uma limitação no tamanho das mesmas devido ao porta-amostras. Um breve histórico, desde o surgimento deste microscópio até os dias atuais, e uma abordagem mais aprofundada sobre o seu funcionamento serão apresentados, explicitando, dessa forma, a importância deste poderoso equipamento para a Ciência e Engenharia dos Materiai

ANÁLISE MORFOLÓGICA DAS FOLHAS DE Anacardium occidentale L.

In morphological studies are analyzed various parameters, ranging from macro scale through the micro scale to the nanometer scale, which contribute to the study of taxonomy, pharmacognosy, ecology, among others. Among the structures found in plants, the leaves are most organs analyzed. This study aimed to analyze morphological features of the leaves of the cashew tree, which is a plant of great commercial importance in Brazil. In this work we observed sinuous epidermal cells in the adaxial and abaxial, characterize their stomata in paracytic surrounded subsidiaries cells. On the abaxial surface the presence of glandular trichomes was observed; and cross-sectional analysis showed a single-layered epidermis with compact mesophyll and several layers of parenchyma cells.Keywords: leaf anatomy; cashew tree; optical microscopy.Em estudos morfológicos são analisados vários parâmetros, que vão desde a escala macro,passando pela escala micro, até a escala nanométrica, que contribuem para os estudos de taxonomia, farmacognosia, ecologia, entre outros. Dentre as estruturas encontradas nas plantas, as folhas são os órgãos mais analisados. Este estudo teve como objetivo analisar características morfológicas das folhas do cajueiro, que é uma planta de grande relevância comercial no Brasil. Neste trabalho foi possível observar células epidérmicas sinuosas nas faces adaxial e abaxial, caracterizar seus estômatos em paracíticos circundados de células subsidiárias. Na face abaxial foi observada a presença de um tricoma glandular; e em análise de corte transversal apresentou uma epiderme uniestratificada, com mesófilo compacto e várias camadas de células parenquimáticas.Palavras-chave: anatomia foliar, cajueiro, microscopia óptica

The activity of methylene blue against asexual and sexual stages of Plasmodium vivax

Methylene blue (MB) is an alternative for combating drug-resistant malaria parasites. Its transmission-blocking potential has been demonstrated in vivo in murine models, in vitro, and in clinical trials. MB shows high efficacy against Plasmodium vivax asexual stages; however, its efficacy in sexual stages is unknown. In this study, we evaluated the potential of MB against asexual and sexual forms of P. vivax isolated from the blood of patients residing in the Brazilian Amazon. An ex vivo schizont maturation assay, zygote to ookinete transformation assay, direct membrane feed assay (DMFA), and standard membrane feed assay (SMFA) using P. vivax gametocytes with MB exposure were performed. A cytotoxicity assay was also performed on freshly collected peripheral blood mononuclear cells (PBMCs) and the hepatocyte carcinoma cell line HepG2. MB inhibited the P. vivax schizont maturation and demonstrated an IC50 lower than that of chloroquine (control drug). In the sexual forms, the MB demonstrated a high level of inhibition in the transformation of the zygotes into ookinetes. In the DMFA, MB did not considerably affect the infection rate and showed low inhibition, but it demonstrated a slight decrease in the infection intensity in all tested concentrations. In contrast, in the SMFA, MB was able to completely block the transmission at the highest concentration (20 µM). MB demonstrated low cytotoxicity to fresh PBMCs but demonstrated higher cytotoxicity to the hepatocyte carcinoma cell line HepG2. These results show that MB may be a potential drug for vivax malaria treatment

EpIG‐DB: A database of vascular epiphyte assemblages in the Neotropics

Vascular epiphytes are a diverse and conspicuous component of biodiversity in tropical and subtropical forests. Yet, the patterns and drivers of epiphyte assemblages are poorly studied in comparison with soil‐rooted plants. Current knowledge about diversity patterns of epiphytes mainly stems from local studies or floristic inventories, but this information has not yet been integrated to allow a better understanding of large‐scale distribution patterns. EpIG‐DB, the first database on epiphyte assemblages at the continental scale, resulted from an exhaustive compilation of published and unpublished inventory data from the Neotropics. The current version of EpIG‐DB consists of 463,196 individual epiphytes from 3,005 species, which were collected from a total of 18,148 relevés (host trees and ‘understory’ plots). EpIG‐DB reports the occurrence of ‘true’ epiphytes, hemiepiphytes and nomadic vines, including information on their cover, abundance, frequency and biomass. Most records (97%) correspond to sampled host trees, 76% of them aggregated in forest plots. The data is stored in a TURBOVEG database using the most up‐to‐date checklist of vascular epiphytes. A total of 18 additional fields were created for the standardization of associated data commonly used in epiphyte ecology (e.g. by considering different sampling methods). EpIG‐DB currently covers six major biomes across the whole latitudinal range of epiphytes in the Neotropics but welcomes data globally. This novel database provides, for the first time, unique biodiversity data on epiphytes for the Neotropics and unified guidelines for future collection of epiphyte data. EpIG‐DB will allow exploration of new ways to study the community ecology and biogeography of vascular epiphytes

MORPHOLOGICAL ANALYSIS OF THE LEAVES OF <i>Anacardium occidentale</i> L.

In morphological studies are analyzed various parameters, ranging from macro scale through the micro scale to the nanometer scale, which contribute to the study of taxonomy, pharmacognosy, ecology, among others. Among the structures found in plants, the leaves are most organs analyzed. This study aimed to analyze morphological features of the leaves of the cashew tree, which is a plant of great commercial importance in Brazil. In this work we observed sinuous epidermal cells in the adaxial and abaxial, characterize their stomata in paracytic surrounded subsidiaries cells. On the abaxial surface the presence of glandular trichomes was observed; and cross-sectional analysis showed a single-layered epidermis with compact mesophyll and several layers of parenchyma cells. Keywords: leaf anatomy; cashew tree; optical microscopy

O Microscópio de Força Atômica (AFM): importante ferramenta no estudo da morfologia de superfícies na escala nanométrica

O surgimento do Microscópio de Força Atômica (AFM) promoveu um grande impacto na Ciência, de uma forma geral, devido a sua capacidade de gerar imagens com resolução atômica, proporcionando o estudo da morfologia de superfícies, condutoras ou não, em escala nanométrica. Além disso, o AFM não exige uma preparação prévia das amostras a serem estudadas, possuindo apenas uma limitação no tamanho das mesmas devido ao porta-amostras. Um breve histórico, desde o surgimento deste microscópio até os dias atuais, e uma abordagem mais aprofundada sobre o seu funcionamento serão apresentados, explicitando, dessa forma, a importância deste poderoso equipamento para a Ciência e Engenharia dos Materiais</p

<b>Wettability and morphology of the leaf surface in cashew tree from the Amazon, Northern Brazil

Leaves surfaces, which represent an interface with plants and the environment, have several structures with specific functions. Some foliar properties, including wettability and mechanical containment, are inferred in terms of cellular adaptation and the presence or absence of cuticular wax. Various morphological parameters, ranging from macro- to nano scales, are analyzed and contribute to the study of taxonomy, pharmacognosy, and ecology of plants. The aim of this paper was to analyze the effect and influence of epicuticular wax granules on the hydrophobicity of Anacardium occidentale L. leaf surfaces. Leaf specimens were directly examined with an environmental scanning electron microscope without metal coating. Images revealed epidermis ornament, stomata type, was, and trichomes. Static contact angle between water and the surface was also measured on both sides. On the adaxial side, an angle of 104.09° ± 0.95° was found, suggesting that adaxial surface is hydrophobic. On the abaxial side, the angle was 62.20° ± 1.60°, which indicates a hydrophilic nature, probably because of the greater amount of epicuticular wax on the adaxial leaf surface. The present investigation provided an important contribution to morphological and ultrastructural characterization of leaves of cashew tree, which is a plant of great medicinal and economic importance.