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Influência diversidade genética, de fatores ambientais e da fenologia sobre o metabolismo secundário de Tithonia diversifolia HEMSL (ASTERACEAE).
No full textTithonia diversifolia belongs to the Asteraceae family, is native from Mexico and widely distributed in tropical and subtropical regions. It is a plant used in countries of Central America, South America, Africa and Asia for the treatment of diseases as diabetes, malaria, abscesses, bruises, skin infections, gastric ulcer, diarrhea, menstrual cramps and wounds. More than 150 compounds were isolated from T. diversifolia, and their main chemical constituents are sesquiterpene lactones, flavonoids and phenolic compounds derived from trans-cinnamic acid. Secondary metabolites act as a chemical interface between plants and the surrounding environment, so their synthesis is often affected by environmental conditions. The production of secondary metabolites is determined by four main factors: genetic, ontogenic, morphogenetic and environmental. The quality of the phytotherapic product results from the interaction between the conditions of the growth site of the medicinal plants and the genetic characteristics of the population. The objectives of this work were to evaluate the genetic diversity of populations of T. diversifolia through RAPD genetic markers, as well as to analyze the influence of environmental and phenological factors in the production of phenolic compounds, besides the antioxidant, cytotoxic and mutagenic activity of these plants. The results demonstrated high levels of genetic diversity were found, not positively correlated with geographical proximity, and the population of Santa Teresa (ST) presented a lower similarity than the others. T. diversifolia reproduces sexually, with abundant seed production and a great variety of pollinating insects, characteristics that contribute to a greater genetic variability. The levels of phenolic compounds were higher in the ST population at the vegetative stage, as well as, in general, also showed the higher antioxidant activity. Among the environmental factors considered, the temperature seems to act more significantly in the production of phenolic compounds in T. diversifolia. The phytochemical composition of plants may vary significantly during the phenological cycle. Therefore, it is very important to identify and select ideal ontogenic stages, to produce the largest quantities of bioactive compounds and guarantee homogeneity of the quality of the raw material. In general, the highest levels of phenolic compounds were found in the plants collected at the vegetative stage. The extract showed a higher cytotoxic activity on the cancer cell line (S180), which shows that the extract acts differentially in the two cell lines evaluated (S180 and human lymphocytes). This characteristic highlights that T. diversifolia presents therapeutic potential for the development of new drugs. The extract of the investigated plant showed no mutagenic activity in peripheral blood cells of mice. This study indicates that phytochemical and antioxidant variations among populations are influenced by genetic factors and phenological stage, as well as by environmental conditions.Tithonia diversifolia pertence à família Asteraceae, é originária do México e encontra-se amplamente distribuída nas regiões tropicais e subtropicais. É uma planta utilizada em países da América Central, América do Sul, África e Ásia para o tratamento de doenças e enfermidades como diabetes, malária, abscessos, hematomas, infecções de pele, úlcera gástrica, diarreias, cólicas menstruais e feridas. Mais de 150 compostos foram isolados de T. diversifolia, sendo seus principais constituintes químicos as lactonas sesquiterpênicas, flavonoides e compostos fenólicos derivados do ácido trans-cinâmico. Os metabólitos secundários atuam como uma interface química entre as plantas e o ambiente circundante, portanto, sua síntese é frequentemente afetada por condições ambientais. A produção de metabólitos secundários é determinada por quatro fatores principais: genéticos, ontogênicos, morfogenéticos e ambientais. A qualidade do produto fitoterápico resulta da interação entre as condições do local de crescimento das plantas medicinais e as características genéticas da população. Os objetivos deste trabalho foram avaliar a diversidade genética de populações de T. diversifolia através de marcadores genéticos, do tipo RAPD, bem como analisar a influência dos fatores ambientais e fenológicos na produção de compostos fenólicos, além da atividade antioxidante, citotóxica e mutagênica dessas plantas. Os resultados demonstraram altos níveis de diversidade genética, não positivamente correlacionado com a proximidade geográfica, sendo que a população de Santa Teresa (ST) apresentou menor similaridade em relação às demais. T. diversifolia se reproduz sexuadamente, com a produção abundante de sementes e grande variedade de insetos polinizadores, características que contribuem para uma maior variabilidade genética. Os teores de compostos fenólicos mostraram-se mais elevados na população de ST no estádio vegetativo, assim como, de modo geral, também apresentou a maior atividade antioxidante. Dentre os fatores ambientais considerados, a temperatura parece atuar de forma mais significativa na produção dos compostos fenólicos em T. diversifolia. A composição fitoquímica das espécies pode variar significativamente durante o ciclo fenológico. Portanto, é muito importante identificar e selecionar estágios ontogênicos ideais, para produção das maiores quantidades de compostos bioativos e garantia de homogeneidade da qualidade da matéria-prima. De forma geral, os maiores teores de compostos fenólicos foram encontrados nas plantas
coletadas no estágio vegetativo. O extrato avaliado apresentou maior atividade citotóxica sobre a linhagem celular cancerígena (S180), o que demonstra que o extrato atua de forma diferencial nas duas linhagens celulares avaliadas (S180 e linfócitos humanos). Essa característica ressalta que T. diversifolia apresenta potencial terapêutico para o desenvolvimento de novos fármacos. O extrato da planta investigada não mostrou atividade mutagênica em células de sangue periférico de camundongos. Este estudo indica que as variações fitoquímicas e antioxidantes entre as populações são influenciadas por fatores genéticos e pelo estágio fenológico, bem como pelas condições ambientais
Análise da expressão gênica e atividade enzimática antioxidante em Passiflora edulis SIMS sob diferentes concentrações de alumínio
Full text linkThe passion fruit is cultivated in almost all the brazilian territory. The Espírito Santo State currently ranks fourth in production in the country. The production of Espírito Santo, Passiflora edulis, is expanding, given that in recent years there has been an increase in planted area of 500 ha of passion, in 1990 to 2,429 ha in March 2008, reaching 2010 in December, 2800 ha planted. However, most of the production in Espírito Santo is still concentrated in the northern region of the state, especially the municipalities of the Jaguaré and Sooretama. While the numbers show progress in the production of fruit, the Espírito Santo is characterized by acidic soils and high aluminum content. Among the responses triggered by exposure to aluminum are: inhibition of root growth, inhibition of cell division, nutrient deficiency, and the activation of signaling pathways and changes in level of protein and RNA transcripts. Thus, it becomes important to study the components of the antioxidant defense system in plants undergoing exposure to aluminum. The ROS can pose serious threat to the cell, one of the responses to environmental stresses such as toxic aluminum. However, few studies have reported the effects of Al on the plant canopy. Therefore, the objective of this study was to evaluate the response of the antioxidant system P.edulis under such conditions. The study of the oxidative stress induced by aluminum showed that the CAT and SOD gene expression of was increased in plants in the nutrient solution and only cv. FB100 this increase was accompanied by increment enzymatic activity of SOD, indicating the higher efficiency of the removal of ROS. Plants grown in the field showed that the expression of antioxidant enzymes in the crop with high aluminum content was not activated at the time of collection, despite the high activity of SOD and APX. This response was possibly determined by the extended time to which the plants were exposed to stress.O maracujazeiro é cultivado em quase todo o território brasileiro. O Estado do Espírito Santo atualmente ocupa o quarto lugar em produção no país. A produção capixaba, de Passiflora edulis, está em expansão, tendo em vista que nos últimos anos houve um aumento na área plantada de maracujazeiro de 500 ha, em 1990, para 2.429 ha, em março de 2008, atingindo em dezembro de 2010, 2.800 ha plantados. Contudo, a maior parte da produção capixaba ainda se concentra na região norte do Estado, com destaque para os municípios de Jaguaré e Sooretama. Apesar dos números mostrarem avanços na produção dessa frutífera, o Espírito
Santo é caracterizado por solos ácidos e alto teor de alumínio. Dentre as respostas desencadeadas pela exposição ao alumínio estão: inibição do crescimento radicular, inibição da divisão celular, deficiência de nutrientes, além da ativação de rotas de sinalização e alterações em nível de proteínas e transcritos de RNA. Dessa forma, torna-se fundamental o estudo de componentes do sistema de defesa antioxidativo
do maracujazeiro cultivado sob exposição ao alumínio. As EROs podem representar grave ameaça à célula, sendo uma das respostas aos estresses ambientais, como a toxidez por alumínio. Contudo, poucos trabalhos têm relatado os efeitos do Al na parte aérea da planta. Por isso, o objetivo deste trabalho foi verificar a resposta o sistema antioxidante de P.edulis sob tais condições. O estudo do estresse oxidativo induzido por alumínio demonstrou que a expressão do gene Cat e Sod foi
aumentada nas plantas em solução nutritiva, e somente na cv. FB100 esse aumento foi acompanhado pelo incremento da atividade enzimática de SOD, o que indica maior eficiência desta na remoção de EROs. As plantas cultivadas em campo demonstraram que a expressão das enzimas antioxidantes na lavoura com alto teor de alumínio não estava ativada no momento da coleta, apesar da elevada atividade de SOD e APX. Esta resposta possivelmente foi determinada pelo tempo prolongado
ao qual as plantas estavam expostas ao estresse
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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