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Comparing feeding and reproductive parameters of Amblyomma parvum tick populations (Acari: Ixodidae) from Brazil and Argentina on various host species
No full textAmblyomma parvum is a Neotropical tick that is widely spread and a potential vector of pathogens, including Rickettsiae. Genetic differences are remarkable between A. parvum populations from Brazil and Argentina. In this work, feeding and reproduction parameters of A. parvum ticks from these two populations were compared on some key host species to evaluate possible differences in host suitability between them. On the whole parameters of these tick populations were similar when fed on the same host and varied similarly on different host species. Still, bovines were more suitable host for Argentinian larvae than for Brazilian cohorts. It was observed that guinea pigs were the best host A. parvum immatures from both origins, as depicted from higher recovery rate of larvae and heavier engorged nymph weights. Canids and bovids were host species most suitable to adults of both tick populations as shown by the highest number of larvae produced by adult females that engorged on these hosts. Taken together, results showed that in spite of the genetic divergence, A. parvum from Argentina and Brazil have similar biological performance on various host species.Fil: Gerardi, Monize. Universidade Federal de Uberlândia. Faculdade de Medicina Veterinária; Brasil. Universidade Federal de Uberlândia. Instituto de Ciências Biomédicas; BrasilFil: Martins, Maria Marlene. Universidade Federal de Uberlândia. Faculdade de Medicina Veterinária; Brasil. Universidade Federal de Uberlândia. Instituto de Ciências Biomédicas; BrasilFil: Nava, Santiago. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Santa Fe. Estacion Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; ArgentinaFil: Juan Szabó, Matias Pablo. Universidade Federal de Uberlândia. Faculdade de Medicina Veterinária; Brasil. Universidade Federal de Uberlândia. Instituto de Ciências Biomédicas; Brasi
Biologia comparada de carrapatos Amblyomma parvum (Acari: Ixodidae) do Brasil e da Argentina
Get PDFThe study of tick-parasite relationships can provide a range of information, including those necessary for the prevention of parasitic and/or infectious diseases. Widely distributed in the Neotropics, Amblyomma parvum ticks can feed in several animal species, including man, besides being a potential reservoir and/or vector of pathogens. Populations of A. parvum from Brazil and Argentina have significant genetic divergence (3.0 - 3.7%) and contrasting reports of host species. This study evaluated the reproductive compatibility between ticks from Argentina and from Brazil and compared the biology of parasites from the two sources in a few animal species. In addition, we also evaluated the capacity of guinea pigs to develop resistance to successive infestations with ticks from both sources, as well as the skin reaction in sensitized guinea pigs by infestation with parasites from Brazil. It was observed that the descendants of crosses between ticks from different origins are fertile, demonstrated by the hatching rate of eggs of hybrid ticks. Guinea pigs were the best hosts for immature forms, and dogs and bovines for adult ticks from both sources, given the highest recovery rate of larvae, the greatest weight of engorged nymphs and the highest number of larvae produced by a female on these hosts. It was also observed that bovines are more suitable hosts for larvae from Argentina than for Brazilian cohorts, which may indicate an adaptation and possibly stabilization of a surrogate life cycle in this non-Neotropical host. Guinea pigs did not develop resistance to repeated infestation by A. parvum ticks from Brazil, as shown by the enhancement of the immature performance on these animals in the third infestation. Also, these hosts did not express hypersensitivity to the tick extract, as seen in the development of reduced skin reactions in test animals, like the control animals. We conclude that the biology of A. parvum ticks from Brazil and from Argentina is very similar. It was evident that cavies can act as primary hosts for immature forms of Brazilian A. parvum as they are for those from Argentina, and its true role in the maintenance of larvae and nymphs of this parasite should be better investigated in Brazil. Finally, we emphasize that the genetic divergence found between ticks from the two sources is not enough to isolate them reproductively and the importance of reevaluate the mitochondrial 16S rDNA gene for distinguishing species of ticks.Conselho Nacional de Desenvolvimento Científico e TecnológicoMestre em Imunologia e Parasitologia AplicadasO estudo das relações hospedeiro-carrapato pode fornecer uma gama de informações, incluindo aquelas necessárias para a prevenção de doenças parasitárias e/ou infecciosas. De ampla distribuição Neotropical, o carrapato Amblyomma parvum é capaz de se alimentar em várias espécies animais, inclusive o homem, além de ser potencial reservatório e/ou vetor de patógenos. Populações de A. parvum do Brasil e da Argentina apresentam divergência genética significante (3,0 - 3,7%) e relatos de espécies hospedeiras contrastantes. O presente trabalho avaliou a compatibilidade reprodutiva entre carrapatos da Argentina e do Brasil e comparou a biologia de parasitos das duas origens em algumas espécies animais. Além disso, buscou-se compreender também se cobaias desenvolvem resistência a sucessivas infestações com carrapatos de ambas as origens, bem como, avaliar a reação cutânea em cobaias sensibilizadas por infestação com parasitos do Brasil. Foi observado que descendentes do cruzamento entre carrapatos de origens distintas são férteis, demonstrado pela taxa de eclosão de larvas de carrapatos híbridos. Cobaias foram os melhores hospedeiros para as formas imaturas e, cães e bovinos, para as formas adultas de carrapatos de ambas as origens, dadas a recuperação de larvas, peso de ninfas e produção de larvas por uma fêmea maiores nestes hospedeiros. Foi observado ainda, que bovinos são hospedeiros mais adequados para larvas da Argentina que para larvas do Brasil, o que pode indicar uma adaptação e eventualmente, estabilização de um substituto ciclo de vida neste hospedeiro não-Neotropical. Cobaias não desenvolveram resistência a repetidas infestações por A. parvum do Brasil, como mostrado pelo favorecimento do desempenho de formas imaturas na terceira infestação destes animais. Também, não expressaram reação de hipersensibilidade ao extrato do carrapato, como visto no desenvolvimento de reações cutâneas reduzidas nos animais testados, à semelhança dos animais controle. Conclui-se que a biologia de A. parvum do Brasil e da Argentina é bastante semelhante. Ficou evidente que preás podem agir como hospedeiros primários para imaturos de A. parvum do Brasil assim como o são para aqueles da Argentina, e seu verdadeiro papel na manutenção de larvas e ninfas deste parasito deve ser melhor investigado no Brasil. Por fim, ressalta-se que a divergência genética encontrada entre carrapatos das duas origens não é suficiente para isolá-los reprodutivamente e a importância da reavaliação da utilização do gene mitocondrial 16S de rDNA para a distinção de espécies de ixodídeos
Genetic profile and susceptibility of different Amblyomma sculptum tick populations to infection by Rickettsia rickettsia pathogen
No full textRecentemente, o táxon Amblyomma cajennense sofreu uma divisão sistemática, através de estudos morfológicos, moleculares e biológicos. No Brasil, Amblyomma sculptum (pertencente ao complexo Amblyomma cajennense) tem sua importância em saúde pública relacionada à transmissão de Rickettsia rickettsii, agente etiológico da Febre Maculosa, doença esta considerada de maior importância dentre as enfermidades transmitidas por carrapatos na América Latina. A Febre Maculosa Brasileira (FMB) tem seu destaque de ocorrência na região sudeste do país, onde A. sculptum está bem estabelecido e quase sempre relacionado à presença de capivaras. Porém, nem todas as áreas da região sudeste com presença de carrapatos A. sculptum e capivaras tem notificações de transmissão de R. rickettsii para humanos. O intuito do presente estudo foi avaliar, em condições de laboratório, a susceptibilidade da infecção por R. rickettsii em seis populações geograficamente distintas de A. sculptum. Dessa forma, foi realizada a quantificação da perpetuação transestadial, da transmissão transovariana e de possíveis efeitos deletérios da infecção nos carrapatos. Além disso, tentou-se correlacionar a susceptibilidade à infecção das diferentes populações de carrapatos (de áreas endêmicas e não endêmicas para FMB) ao perfil genético das mesmas, através dos marcadores 16S rDNA mitocondrial e ITS2 nuclear. Com base nos resultados encontrados, pode-se constatar diferenças na susceptibilidade à infecção por R. rickettsii entre as seis populações de A. sculptum estudadas, muito embora todas elas se mostraram parcialmente refratárias à infecção por R. rickettsii. No entanto, não foi observado nenhum padrão específico de variabilidade nos parâmetros biológicos e reprodutivos de carrapatos infectados e não infectados. A partir dos resultados de caracterização molecular, não foi possível verificar divergências genéticas entre as diferentes populações para o marcador ITS2 nuclear. Da mesma forma, com a análise do marcador 16S rDNA mitocondrial não constatou-se divergências genéticas que pudessem ser atribuídas à maior susceptibilidade ou refratariedade dos carrapatos à infecção por R. rickettsii. Porém, vale ressaltar que variabilidade nucleotídica neste marcador foi observada entre algumas populações, que parece seguir padrões geográficos de origem. A exceção para este resultado foi a população de Belo Horizonte (Pampulha), que apresentou variabilidade intrapopulacional, com genótipo semelhante à população do Parque Nacional Grande Sertão Veredas (GSV), ambas do estado de Minas Gerais e um segundo genótipo idêntico ao de Itu, no estado de São PauloRecently, the taxon Amblyomma cajennense taxon resulted in a systematic division, through morphological, molecular and biological studies. In Brazil, Amblyomma sculptum (belonging to the Amblyomma cajennense complex) has its importance in public health related to Rickettsia rickettsii transmission, the etiologic agent of spotted fever, disease that is considered the most important among the tick-borne diseases in Latin America. Brazilian Spotted Fever (BSF) has its occurrence in the southeastern region of the country where A. sculptum is well established and is almost always related to presence of capybaras. However, not all areas of southeastern of Brazil with A. sculptum ticks and capybaras have notifications of transmission of R. rickettsii to humans. This study aimed to evaluate, under laboratory conditions, the R. rickettsii susceptibility among six geographically distinct populations of A. sculptum. To this purpose, the transestadial perpetuation, transovarial transmission and possible deleterious effects of R. rickettsii infection were quantified in the six tick populations. In addition, we attempted to correlate the susceptibility to infection of different populations of ticks (from BSF-endemic and BSF-non-endemic areas) to the genetic profile of them through the markers mitochondrial 16S rDNA and nuclear ITS2. The results show differences in the susceptibility to infection with R. rickettsii among the six A. sculptum populations, although all populations were partially refractory to R. rickettsii infection. However, it was not observed any specific pattern of variation in biological and reproductive parameters of infected and uninfected ticks. Results of molecular characterization did not indicate genetic divergence between the populations for nuclear ITS2 marker. In the same way, analysis of mitochondrial 16S rDNA marker found no genetic differences that could be attributed to increased susceptibility or refractory of ticks to infection by R. rickettsii. However, it is note worth that nucleotide variability in this marker was observed among some populations, which seems to follow geographical patterns of origin. The exception to this result was the Belo Horizonte (Pampulha) population, which showed intrapopulation variability, having a similar genotype to the Grande Sertão Veredas population (GSV), both from the state of Minas Gerais and a second identical genotype to the Itu, from the state of São Paul
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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