Giardia lamblia is a protozoan that inhabits the small intestine of vertebrates, attaching to the epithelial cells by means of cytoskeletal elements. G. lamblia trophozoites possess several microtubular structures, namely the adhesive disc, the median body, the funis and the four pairs of flagella. Several drugs that target cytoskeletal proteins have been used in the study of cytoskeletal function and dynamics. In this work, we used oryzalin, which binds to alpha-tubulin, as a tool to study the Giardia cytoskeleton. The trophozoites were treated with oryzalin, and its effects were analysed by immunofluorescency, transmission and scanning electron microscopies. Oryzalin inhibited Giardia proliferation. Treated cells were not able to complete cell division and had flagella showing extensive shortening. Strikingly, the drug did not interfere with the adhesive disc, in contrast to what happens when other drugs are used.
Among the epistemological obstacles described by Gaston Bachelard, we contend that unitary and pragmatic knowledge is correlated to the teleological categories of Ernst Mayr and is the basis for prevailing debate on the notion of "function" in biology. Given the proximity of the aspects highlighted by these authors, we propose to associate the role of teleological thinking in biology and the notion of unitary and pragmatic knowledge as an obstacle to scientific knowledge. Thus, teleological thinking persists acting as an epistemological obstacle in biology, according to Bachelardian terminology. Our investigation led us to formulate the "teleological obstacle," which we consider important for the future of biology and possibly other sciences. Palavras-chave: Gaston Bachelard (1884-1962 obstáculos epistemológicos; Ernst Mayr (1904-2005
BackgroundGiardia lamblia is a multiflagellated protozoan that inhabits the small intestine of vertebrates, causing giardiasis. To colonize the small intestine, the trophozoites form of the parasite remains attached to intestinal epithelial cells by means of cytoskeletal elements that form a structure known as the ventral disc. Previous studies have shown that the ventral disc is made of tubulin and giardins.ResultsTo obtain further information on the composition of the ventral disc, we developed a new protocol and evaluated the purity of the isolation by transmission electron microscopy. Using 1D- and 2D-PAGE and mass spectrometry, we identified proteins with functions associated with the disc. In addition to finding tubulin and giardin, proteins known to be associated with the ventral disc, we also identified proteins annotated in the Giardia genome, but whose function was previously unknown.ConclusionsThe isolation of the ventral disc shown in this work, compared to previously published protocols, proved to be more efficient. Proteomic analysis showed the presence of several proteins whose further characterization may help in the elucidation of the mechanisms involved in the attachment of the protozoan to epithelial cells.
O presente artigo apresenta e reflete sobre a origem, definições e características do método Estudo de Caso. Observa os limites do Estudo de Caso como método de pesquisa. Apresenta sua aplicabilidade em pesquisas científicas da área da Ciência da Informação no Brasil, com a análise de treze periódicos recomendados pela ANCIB. Demonstra a aplicação do método em cinco artigos publicados no período de 2007 a 2011. Conclui que o Estudo de Caso se aplicado corretamente pode contribuir como método e ajudar a ampliar as pesquisas em Ciência da Informação no Brasil.
ResumoNeste trabalho, buscou-se identificar obstáculos epistemológicos entre os presentes na XXXIX Reunião Anual da Sociedade Brasileira de Bioquímica e Biologia Molecular (SBBq). Um questionário com perguntas e excertos de artigos científicos de revistas de alto fator de impacto foi respondido por 97 presentes (39 estudantes de iniciação científica, 42 pós-graduandos e 16 professores e pesquisadores). A partir da noção de obstáculo epistemológico proposta por Bachelard, foi possível identificar concepções vitalistas (animismo), concepções teleológicas dos processos evolutivos, em afirmações como a existência de objetivos/finalidades na adaptação dos organismos, assim como uma visão antropomórfica dos processos biológicos em avaliação, tanto nas respostas às perguntas como na aceitação ou não identificação destes obstáculos nos excertos. Verificou-se a presença de figuras de linguagem, metáforas e analogias (obstáculo verbal) na explicação da evolução e do sistema imune, também presentes nos excertos dos artigos. Palavras-chave: antropomorfismo; teleologia; vitalismo. Abstract The aim of this work was to identify epistemological obstacles amongst participants of XXXIX Annual Meeting of Brazilian Society of Biochemistry and Molecular
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