Augusto Mello Simões Barbosa

Formação

• Pós-Doutorado - Periodo: 2004 a 2009 - University of Califonia Los Angeles
• Doutorado - Periodo: 1996 a 2000 - Patologia Molecular
  Universidade de Brasília
• Especialização - Periodo: 2000 a 2001 - Manipulação Genética de Bactérias do Ácido Láctico
  Institut National de la Recherche Agronomique
• Aperfeiçoamento - Periodo: 1995 a 1996 - Genética molecular humana
  Universitat Gottingen
• Graduação - Periodo: 1992 a 1995 - Ciências Biológicas
  Universidade de Brasília

Atuação Profissional

• Experimental Parasitology- / Periodo: 2005 a atual
• Memórias do Instituto Oswaldo Cruz (Impresso)- / Periodo: 2012 a 2012
• PLoS Neglected Tropical Diseases (Print)- / Periodo: 2011 a 2011
• The University of Auckland- / Periodo: 2010 a atual
• Universidade Católica de Brasília-UCB / Periodo: 2000 a 2004
• University of Califonia Los Angeles- / Periodo: 2009 a 2010
• University of Califonia Los Angeles- / Periodo: 2004 a 2009

Linha de Pesquisa

• Bases moleculares de patogênese na infecção por Trichomonas vaginalis e mecanismos de intervenção
• Expressão gênica e processamento de RNA em Trichomonas vaginalis
• Gene expression and RNA processing in Trichomonas vaginalis and Giardia lamblia
• O projeto genoma do parasito humano Trichomonas vaginalis
• Proteoma do hidrogenosoma do Trichomonas vaginalis
• The interaction between Lactobacillus and Trichomonas vaginalis

Projetos de Pesquisa

• The interaction of Lactobacillus and Trichomonas vaginalis
  Período: 2011 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Caracterizacao funcional da maquinaria de capping de RNA em Trichomonas vaginalis
  Período: 2007 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Caracterizacao dos sinais minimos de splicing de RNA, sitios 5` e 3` de splicing e sitio de ramificacao, em Trichomonas vaginalis
  O genoma do Trichomonas vaginalis permitiu a identificacao de 65 genes contendo introns, alguns dos quais necessitam de validacao. Verificamos uma variacao de sinais de splicing nestas sequencias, como o sinais minimos propostos anteriormente. Pretendemos neste estudo utilizar um gene reporter interrompido por diferentes sequencias intronicas e, atraves de mutagenese e transfeccao, caracterizar in vivo os sinais minimos para o splicing de RNA neste organismo.
  Período: 2008 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Caracterizacao da estrututura cap 0, cap1 e cap2 em RNAs mensageiros do Trichomonas vaginalis
  Em trabalhos anteriores demonstramos que RNA mensageiros em T. vaginalis sao providos de cap 5` (RNA, 2008), e que este organismo tambem possui uma enzima tipo Tgs, que promove a hipermetilacao da estrutura cap, mas que ao contrario de outros eucariotos e` capaz de apenas um ciclo de metilacao (JBC, 2008). Pretendemos neste estudo, determinar a real estrutura cap do RNA mensageiro do Trichomonas vaginalis, atraves de marcacao radioativa, isolamento e digestao enzimatica do RNA, e analise em cromatografia 2D-TLC. Em linhas gerais, o cap do RNA mensageiro em eucariotos pode apresentar metilacoes na guanosina cap 5` (cap 0), no primeiro (cap 1) e segundo nucleotideo (cap 2).
  Período: 2008 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Busca e identificacao de especies de RNAs com cap 0 di- e trimetilados em Trichomonas vaginalis
  Com o achado de que snRNA spliceosomais nao possuem estrutura cap 5` bem como de que a enzima TriMetilGuanosina Sintase realiza apenas em ciclo de metilacao em Trichomonas vaginalis, abre-se a perspectiva de que existam RNA com cap 0 dimetilado. Nao podemos descartar a possibilidade de uma segunda enzima nao identificavel no genoma ou que algum outro fator permita o segundo ciclo de metilacao levando a formacao de um cap 0 trimetilado. Atraves da marcacao radioativa in vivo e in vitro de RNAs, purificacao diferencial de RNAs e analise por cromatografia 2D-TLC, pretende-se neste estudo identificar possiveis especies de RNA com cap 0 di- ou trimetilado. Tambem, a enzima TriMetilGuanosina Sintase recentemente identificada sera` marcada com epitopo para purificacao mediante "pull-down" ou imunoprecipitacao de possivel complexo ribonucleoproteico e identificacao de seus componentes in vivo.
  Período: 2008 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Comparação das propriedades enzimaticas de TriMetilGuanosina sintases recombinantes dos eucariotos divergentes e primitivos Trichomonas vaginalis, Giardia lamblia, Entamoeba histolytica e Trypanosoma brucei
  Com os achados de que a enzima TriMetilGuanosina sintase em ambos organismos eucarioticos primitivos Giardia lamblia e Trichomonas vaginalis sao capazes na verdade de apenas um ciclo de metilacao, sugerimos investigar as propriedades desta mesma enzima em outros organismos eucarioticos ditos primitivos ou divergentes na possibilidade de evidenciar um cenario evolutivo comum.
  Período: 2008 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Caracterizacao das especies de RNA presentes em fracao polisossomal associada ao hidrogenosoma em Trichomonas vaginalis
  For decades, it is known that full active polysomes can be found associated to the outer membrane of mitochondria {Kellems, 1974; Ibrahim, 1980}. While mitochondria-bound polysomes (MBP) might contribute to mitochondrial protein import {Suissa, 1982}, genome-wide analysis of mRNAs loaded into these MBPs {Marc, 2002} had further indicated that a mechanism of co-translational import might have appeared during the co-evolution of endosymbiont and the primitive eukaryotic cell. Marc et al (2002) reported that almost half of the studied mRNAs from nuclear genes encoding mitochondrial products were found to be translated in the vicinity of mitochondria. There is indeed a preference for proteins of prokaryotic origin to be translated on MBPs {Marc, 2002}. In addition, 3 UTR sequence/structure was demonstrated to be involved in this process {Corral-Debrinski, 2000; Marc, 2002}. Interestingly, evidence supports that the nascent polypeptide-associated factor NAC does indeed represent a link between translation and mitochondria import {Wiedmann, 1994; Gautschi, 2001; George, 1998; Funfschilling, 1999}. Apart from debates about the common origin of the hydrogenosomes and mitochondria, it is plausible to hypothesize that after losses and transfer of genes of the free-living bacterial ancestor to the host genome hydrogenosomal protein import machinery might have re-evolved a process of optimizing the import of proteins that are needed to establish the organelle function in the cell. Here, we have used quantitative reverse-transcriptase PCR in order to assess relative amount of specific transcripts present in hydrogenosomal-bound polysomes (HBP) and free cytoplasmic polysomes. (CP)
  Período: 2007 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Desenvolvimento de metodologia para "knock-down" da expressao genica em Trichomonas vaginalis
  Em muitos organismos, e` possivel estudar a funcao genica atraves de ferramentas diversas para o "knock-down" da expressao genica, como RNA interferencia. Embora o genoma do Trichomonas vaginalis indique a presenca de alguns elementos centrais da maquinaria de RNAi, tal tecnologia ainda e` indisponivel para este organismo. Neste trabalho, objetivamos desenvolver e caracterizar vias para "knock-down" da expressao genica com enfase em RNAi.
  Período: 2008 - atual / Situação: EM_ANDAMENTO / Natureza: PESQUISA
• Caracterizacao funcional da enzima TriMetilGuanosina Sintase em Trichomonas vaginalis
  Eukaryotic RNAs typically contain 5 cap structures that are thought to provide protection from nuclease digestion, assist in compartmentalization and translocation, and allow efficient translation initiation through interaction with the cap-binding complex eIF-4F. With rare exception, the cap structure(s) of RNAs in divergent unicellular eukaryotes are unknown. mRNAs of the parasite T. vaginalis are protected by a 5 cap structure, however, contrary to that observed in most eukaryotes, T. vaginalis spliceosomal snRNAs lack a cap and may contain 5 monophophates (1). Other eukaryotic snRNAs and snoRNAs typically contain a distinctive trimethylguanosine cap structure (m2,2,7G) that results from post-transcriptional hypermethylation of a m7G cap catalyzed by the enzyme trimethylguanosine synthase (Tgs). Here, we identify and biochemically characterize T. vaginalis Tgs (TvTgs). Substrate specificity and mutagenesis analyses indicate that TvTgs is an RNA cap-specific, m7G-dependent N2 methyltransferase. However, TvTgs is capable of catalyzing only a single round of N2 methylation forming a 2,7-dimethylguanosine, instead of the 2,2,7 trimethyguanosine cap formed by yeast Tgs. Thus, TvTgs appears to be a dimethylguanosine synthase, similar to that previously described for Giardia lamblia Tgs2. These data predict that these divergent eukaryotes contain RNAs with dimethylguanosine 5 cap structures, a property previously associated exclusively with specific viral RNAs.
  Período: 2005 - 2008 / Situação: CONCLUIDO / Natureza: PESQUISA
• Sequenciamento do genoma do Trichomonas vaginalis
  We describe the genome sequence of the protist Trichomonas vaginalis, a sexually transmitted human pathogen. Repeats and transposable elements comprise about two-thirds of the 160-megabase genome, reflecting a recent massive expansion of genetic material. This expansion, in conjunction with the shaping of metabolic pathways that likely transpired through lateral gene transfer from bacteria, and amplification of specific gene families implicated in pathogenesis and phagocytosis of host proteins may exemplify adaptations of the parasite during its transition to a urogenital environment. The genome sequence predicts previously unknown functions for the hydrogenosome, which support a common evolutionary origin of this unusual organelle with mitochondria.
  Período: 2004 - 2007 / Situação: CONCLUIDO / Natureza: PESQUISA
• Identificação e caracterização dos componentes de snRNA do spliceosoma do Trichomonas vaginalis
  Few genes in the highly divergent eukaryote Trichomonas vaginalis have introns, despite the unusually large gene repertoire of this human-infective parasite. These introns are characterized by extended conserved regulatory motifs at the 5 and 3 boundaries, a feature shared with another divergent eukaryote, Giardia lamblia, but not with metazoan introns. This unusual characteristic of T. vaginalis introns led us to examine spliceosomal small nuclear RNAs (snRNAs) in this organism. Here we identify T. vaginalis U1, U2, U4, U5 and U6 snRNAs, present predictions of their individual secondary structures and that of the U2/U6 snRNA complex interacting with a T. vaginalis intron. These structural models predict that T. vaginalis snRNAs contain conserved sequences and structure motifs strikingly similar to those found in other examined eukaryotes. These data indicate that mechanisms of intron recognition as well as coordination of the two catalytic steps of splicing have been conserved throughout eukaryotic evolution. Unexpectedly, we found that T. vaginalis spliceosomal snRNAs lack the 5 trimethylguanosine cap found in other known snRNAs and appear to possess unmodified 5 ends. Despite the lack of the cap structure, U1, U2, U4 and U5 genes are transcribed by RNA polymerase II, whereas the U6 gene is transcribed by RNA polymerase III.
  Período: 2004 - 2007 / Situação: CONCLUIDO / Natureza: PESQUISA
• Caracterização funcional de genes e proteínas candidatos a fatores citolíticos em Trichomonas vaginalis
  Summary "This work describes the identification of a triacylglycerol lipase named TVLip directly onto blood-LB-agar plates by hemolytic screening of a Trichomonas vaginalis cDNA expression library. Sharing signiWcant similarity in the primary sequence with other lipases, the theoretical 3D structure of the TVLip was resolved. The structure reveals the predictive conserved characteristics of other lipases from EC3.1.1.3 group, although presenting one aminoacid change in the catalytic triad Ser-His-Asp. Finally, analysis of Northern blot indicates that the expression of the TVLip gene is up-regulated by iron."
  Período: 2003 - 2005 / Situação: CONCLUIDO / Natureza: PESQUISA
• Determination of gene expression profiles of Trichomonas vaginalis under different conditions of iron
  Período: 2004 - 2005 / Situação: CONCLUIDO / Natureza: PESQUISA
• Caracterização genética de isolados clínicos de Trichomonas vaginalis
  Vários isolados clínicos oriundos de trabalho anterior (Lobo et al. 2003. A comparative evaluation of the Papanicolaou test for the diagnosis of trichomoniasis. Sex Transm Dis. 30:694-9) foram utilizados neste estudo . Summary: "Trichomoniasis presents a broad spectrum of clinical patterns ranging from asymptomatic to severe vaginitis and cervicitis. Despite its importance, very little is known about the genetic relatedness of its causative agent, Trichomonas vaginalis, and the clinical phenotypes. To address this question, analysis of restriction length polymorphism (RFLP) within the intergenic spacer of the ribosomal DNA (IGS) from 60 clinically deWned isolates of T. vaginalis was performed. This is the Wrst description of the IGS polymorphism of T. vaginalis. As expected, a considerable number of patients were asymptomatic (28%) while only 12% presented both leukorrhea and macular colpitis, the most evident symptoms of trichomoniasis. The IGS RFLP with the use of eight restriction enzymes showed absence of correlation between the genetic relatedness of the isolates and symptomatology. Further studies are necessary to evaluate the importance of the IGS polymorphism to the parasite virulence and clinical phenotype."
  Período: 2002 - 2005 / Situação: CONCLUIDO / Natureza: PESQUISA
• Prospeccao de agentes tricomonicidas em extratos de plantas do Cerrado Brasileiro
  Extrato de plantas do Cerrado serao avaliadas na capacidade de inibir o crescimento celular ou provocar destruicao celular em cultura de Trichomonas vaginalis
  Período: 2004 - 2004 / Situação: DESATIVADO / Natureza: PESQUISA
• Estudo epidemiológico e diagnóstico molecular da tricomoníase no Distrito Federal
  Background: Trichomoniasis is the most prevalent nonviral sexually transmitted disease in humans worldwide. In addition to its pathologic implications, trichomoniasis is a risk factor for the transmission of the HIV and is associated with reproductive complications in females. Diagnosis of the disease is problematic due to inadequate accuracy of current diagnostic methods. Recently developed DNA-based techniques for detection of Trichomonas vaginalis seem to be promising alternatives. Goal: The goal of this study was to evaluate the accuracy of the Papanicolaou test for the diagnosis of trichomoniasis by comparing polymerase chain reaction (PCR) with other current diagnostic methods. Study Design: A total of 1008 cervicovaginal swab specimens from a randomized population attending a gynecological service were analyzed in this study. In addition to current diagnostic methods, two sets of specific primers were used for PCR detection of T vaginalis in the cervicovaginal DNA samples, with a PCR quality control. Different examiners conducted PCR and Papanicolaou analyses in a doubleblind trial. Results: The prevalence of trichomoniasis in this population was 6%. A considerable number of diagnostic results of the Papanicolaou test were false negative or false positive. Compared with PCR, specificity of the Papanicolaou test was 97.6%, whereas sensitivity was only 60.7%. The positive predictive value of the Papanicolaou smear was 61.7%. These results suggest that irregularly shaped parasites without clearly defined nuclei and flagella and bacteria-induced focal cytolysis limit the ability of the Papanicolaou test to detect T vaginalis. Conclusion: The Papanicolaou test, the most readily available cytologic method for screening sexually transmitted pathogens and cellular abnormalities in most developing countries, is inadequate for the diagnosis of trichomoniasis due to its inherent limitations. However, PCR is a highly sensitive d specific test for the diagnosis of
  Período: 2001 - 2003 / Situação: CONCLUIDO / Natureza: PESQUISA
• Diagnóstico e epidemiologia moleculares da infecção pelo HPV: casos de divergência diagnóstica entre captura híbrida e citologia
  As various types of human papillomavirus (HPV) are involved in the pathogenesis of cervical cancer, correct diagnosis is of fundamental importance for screening programs. We evaluated the divergence of results between Papanicolaou cytology and hybrid capture by PCR detection of HPV DNA . A transversal study was conducted on 70 women attending private gynecological clinics in Brasilia, Brazil. PCRs were conducted with specific primers for general and high-risk HPV DNA. Based on the PCR results, hybrid capture was a superior diagnostic technique. When Papanicolaou was compared with the molecular biology methods, it was found that a positive Papanicolaou result does not necessarily indicate the presence of HPV. The agreement between PCR and hybrid capture results can be attributed to the fact that both methods detect latent infection, while Papanicolaou detects only microscopic cellular alterations.
  Período: 2002 - 2003 / Situação: CONCLUIDO / Natureza: PESQUISA
• Manipulação genética de bactérias do ácido láctico para imunização vaginal
  The genetic improvement of Lactococcus lactis is a matter of biotechnological interest in the food industry and in the pharmaceutical and medical fields. However, to construct a food-grade delivery system, both the presence of antibiotic markers or plasmid sequences should be avoided and the maintenance and expression of the cloned gene should be guaranteed. The objective of this work was to produce crossover mutants of L. lactis with a reporter gene under the control of an inducible promoter in order to evaluate the level of gene expression. We utilized a nuclease gene of Staphylococcus aureus as a reporter gene, P(nisA) as the nisin-inducible promoter, a non-essential gene involved in histidine biosynthesis of L. lactis as the site for homologous recombination, and pRV300 as a suicide vector for the genomic integration in L. lactis NZ9000. Single- and double-crossover mutants were identified by genotype and phenotype. Relative to episomal transformants of L. lactis, the level of expression of the heterologous protein after nisin induction was similar in the crossover mutants, suggesting that a single copy of the heterologous gene can be used to produce the protein of interest.
  Período: 2001 - 2002 / Situação: CONCLUIDO / Natureza: PESQUISA

Áreas de Atuação

• Ciências Biológicas :: Biologia Geral :: Biologia Celular ::
• Ciências Biológicas :: Bioquímica :: Biologia Molecular ::
• Ciências Biológicas :: Bioquímica :: Bioquímica dos Microorganismos ::
• Ciências Biológicas :: Genética :: Genética Molecular e de Microorganismos ::
• Ciências Biológicas :: Parasitologia :: Protozoologia de Parasitos ::

Idiomas

• Espanhol: Lê: BEM, Fala: BEM, Escreve: BEM, Compreende: BEM
• Francês: Lê: RAZOAVELMENTE, Fala: NAO_INFORMADO, Escreve: NAO_INFORMADO, Compreende: RAZOAVELMENTE
• Inglês: Lê: BEM, Fala: BEM, Escreve: BEM, Compreende: BEM

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