Blastocystis sp. é um protozoário comumente encontrado em amostras fecais de humanos e animais, envolto por aspectos patogênicos e zoonóticos ainda controversos. Estudos recentes têm demonstrado a distribuição dos subtipos (STs) de Blastocystis sp., porém são escassos os relatos sobre a sua caracterização molecular na América Latina, sobretudo no Brasil. O objetivo do presente estudo foi investigar os STs presentes em isolados fecais de indivíduos acompanhados no Hospital das Clínicas de São Paulo da Faculdade de Medicina da Universidade de São Paulo (HC/FMUSP). Para tanto, amostras fecais positivas para Blastocystis sp. diagnosticadas na Seção de Parasitologia do Laboratório Central (HC/FMUSP) foram utilizadas para o isolamento de DNA. A reação em cadeia da polimerase (PCR) foi realizada utilizando iniciadores específicos para a subunidade 18S do DNA ribossomal de Blastocystis sp. A reação de sequenciamento dos produtos de PCR foi realizada, as sequências de DNA obtidas foram alinhadas e comparadas com outras sequências da base de dados GenBank e MLST. Foram identificados os STs (ST1, ST2, ST3 e ST6), sendo o ST3 o mais prevalente entre os isolados humanos seguido pelo ST1. Os alelos de número 34 e 36 foram os mais frequentes. Em conclusão, estes resultados contribuem para a caracterização molecular e a distribuição dos STs de Blastocystis sp. em amostras de fezes humanas no Brasil. / Blastocystis sp. is an organism described as enteroparasite protozoan, commonly found in stool samples from humans. Several subtypes have been described in humans, but pathogenic potential and aspects epidemiological are still controversial. The aim of the present study was to investigate Blastocystis subtypes (STs) from patients of Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HC/FMUSP), Brazil. Blastocystis sp. positive stool samples diagnosed in Section of Parasitology of Central Laboratory (HC/FMUSP) were used for DNA isolation. Polymerase chain reaction (PCR) was performed using specific primers targeting the small subunit of rRNA gene. Direct DNA sequencing of PCR products was performed, and the DNA sequences were aligned and compared to other sequences present in GenBank and MLST database. Four STs were identified (ST1, ST2, ST3 and ST6), where the ST3 was the most prevalent ST among human isolates followed by ST1. Allele nos. 34 and 36 were the most frequent. Another important finding is the presence of ST6, rarely detected in human isolates. In conclusion, our results contribute to the molecular characterization and distribution of Blastocystis sp. STs in human stool specimens in Brazil.

<p> Sigma S (RpoS), encoded by rpoS, is a subunit of RNA polymerase holoenzyme that controls the expression of many genes in stationary phase of various gram negative bacteria. Escherichia coli expresses these genes to withstand environmental stress and nutrient starvation. Several naturally occurring mutant alleles of the gene have been reported and indicate key differences from laboratory strains. We sought to explore the role of natural alleles of the rpoS gene (from non- K12 strains) and thus the sigma subunit relative to the K12 allele. To study the effect of the rpoS polymorphism on gene expression ofRpoS regulon members, rpoS alleles from ECOR- 21, ECOR-28, ECOR-37 and ECOR-40 as well as MG1655 were cloned into the same background, MG1655 ΔrpoS:cat osmY-lacZ. Sequence analysis showed rpoS alleles from all the natural strains tested were different from MG1655 and each other. The strain with rpoS allele from ECOR-28 had increased expression of osmY and katE similar to MG1655. In contrast, rpoS allele from ECOR- 37 showed low expression of osmYbut not as low as ECOR-21 and ECOR-40 which had expression similar to the rpoS mutant. Not surprisingly, recombinant strains with rpoS alleles from ECOR-21, ECOR-37 and ECOR-40 showed no expression of katE (HPII). These suggest that RpoS in ECOR-28 has high activity similar to wildtype K12 strain while RpoS in ECOR-21, ECOR-37 and ECOR-40 has very low or no activity. We conclude that natural E. coli strains have polymorphism in their rpoS ORF which cause variation in the regulatory activities of RpoS on its regulon. </p> / Thesis / Master of Science (MSc)

No description available.

Understanding the mechanisms and factors that govern cell cycle control is key to developing more effective treatments for human diseases, such as cancer. The human MASTL gene encodes an AGC family kinase, Greatwall kinase, that is conserved among higher eukaryotes. The protein contains an unusual bifurcated kinase domain separated by a stretch of nonconserved amino acids. In Drosophila, mutations in Greatwall cause the failure of chromosomes to condense resulting in a delayed entry in to and progression through mitosis. In mitotic Xenopus egg extracts, immunodepletion of Greatwall results in exit from M phase, characterised by the decondensation of the chromosomes and the reforming of the nuclear envelope. The addition of purified Greatwall to egg extracts immunodepleted for Greatwall causes precocious phosphorylation of Cdc25 and premature entry into mitosis. These reports indicate that Greatwall plays an important role in the control of mitosis but little is known about the function of Greatwall kinase in human cells, its structure, or control of its activity. This project aimed to elucidate the role of this novel kinase in human cells. To this end, the gene has been cloned and antibodies generated to allow the study of human Greatwall kinase. RNAi-mediated knockdown of Greatwall in HeLa cells caused aberrant mitotic progression and apoptosis. To gain further insight into the mechanism of Greatwall activation, the Greatwall kinase structure was modelled and key motifs of the kinase fold identified. In particular, a key activating phosphorylation was identified, and a specific antibody raised to this site, allowing investigation of the regulation of Greatwall activity at mitotic entry and exit. The use of chemical genetics to attempt to specifically inhibit the kinase in human cells is described. Finally, evidence is presented that Greatwall kinase may represent a promising new biomarker and drug target for cancer therapy.

Maintenance of genome integrity and stability is fundamental for any form of life. This is complicated as DNA is highly reactive and always under attack from a wide range of endogenous and exogenous sources which can lead to different damages in the DNA. To preserve the integrity of DNA replication, cells hav evolved a variety of DNA repair pathways. DNA damage tolerance mechanisms serve as the last line of defence to rescue the stalled replications forks. TLS, error-prone type of DNA damage tolerance, acts to bypass DNA lesions and allows continuation of DNA replication. Surprisingly majority of archaeal species lack canonical TLS polymerases. This poses a question as to how archaea restart stalled replication in the absence of TLS or lesion repair pathways. This thesis establishes that archaeal replicative primase (PriS/L), a member of the archaeo-eukaryotic primase (AEP) superfamily, possessing both primase and polymerase activities, is able to bypass the most common oxidative damages and highly distorting lesions caused by UV radiation. It has been postulated that archaeal replicative polymerases (Pol B and Pol D family Pols) can bind tightly to the deaminated bases uracil and cause replication fork stalling four bases prior to dU. A specific mechanism for resuming replication of uracil containing DNA by PriS/L is suggested in this thesis. In this thesis, we also reported how the enzymatic activities of archaeal PriS/L are regulated. Here, it is demonstrated that in contrast to archaeal replicative polymerases, single-strand binding proteins (RPA) significantly limit the polymerase activity of PriS/L. The remaining results chapter interrogates the possible interactions between PriS/L and RPA. Finally, the attempts to reconstitute an archaeal CMG complex in vitro, with the aim of shedding light on the role of archaeal replicative primase in replication-specific TLS are described.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 133-141).

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2010.

Thesis (Ph. D.)--University of Missouri--Columbia, 2002. / Typescript. Vita. Includes bibliographical references (leaves 205-223). Also available on the Internet.

Thesis--University of Oklahoma. / Bibliography: leaves 44-47.

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2012-08-29T21:26:52Z No. of bitstreams: 1 Taisa Manuela Bonfim Machado. Ancestralidade em Salvador - BA.pdf: 1157160 bytes, checksum: b3800dd208ac4ea86750232d8ab8ef3d (MD5) / Made available in DSpace on 2012-08-29T21:26:52Z (GMT). No. of bitstreams: 1 Taisa Manuela Bonfim Machado. Ancestralidade em Salvador - BA.pdf: 1157160 bytes, checksum: b3800dd208ac4ea86750232d8ab8ef3d (MD5) Previous issue date: 2008 / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, Bahia, Brasil / Os ameríndios, africanos e europeus foram identificados como principais formadores da população brasileira e conseqüentemente da população de Salvador. A população brasileira considerada a mais heterogênea do mundo é resultado de 500 anos de miscigenação. Contudo a distribuição dos grupos étnicos ancestrais ao longo do território brasileiro não ocorreu de forma homogênea, diferindo significativamente a depender da região geográfica. Além disso, houve um forte direcionamento entre os casamentos, sendo mais freqüentes as uniões entre homens europeus e mulheres ameríndias e africanas. Dados do IBGE 2000 mostram que em Salvador o percentual de afrodescendentes, por autodenominação é de 79,8%. Para estimarmos a contribuição dos grupos ancestrais nesta população foram analisados 1.286 indivíduos, provenientes da população de Salvador, para os alelos específicos de população AT3-I/D, APO, SB19.3, PV92, FYnull, LPL, CKMM, GC e CYP3A4 que apresentam alto diferencial de freqüência entre os grupos ancestrais. Para estimar a origem africana dos indivíduos também foi avaliada a presença de sobrenome de conotação religiosa. Foram identificados 287 sobrenomes nesta população A freqüência de sobrenomes de conotação religiosa foi de 54,9% na população de Salvador e avaliando as regiões presentes no estudo observamos uma relação inversa entre a classe sócio-econômica e a presença deste tipo de sobrenome. Estes dados foram confirmados por uma maior ancestralidade genômica africana (53,1%) entre indivíduos que apresentam sobrenomes de conotação religiosa. A miscigenação da população de Salvador foi confirmada pela diferença das freqüências desta população com as ancestrais. Assim como pela estimativa de mistura populacional, com contribuição africana de 49,2%; 36,3% européia e 14,5% ameríndia e também pelas análises de heterozigose média (0,397) e estrutura populacional. Foi calculada a estatística F (0,005) que demonstrou que as regiões da cidade de Salvador são diferentes, porém em pequenas proporções. Ao compararmos a estimativa da contribuição africana do IBGE, 2000, por autodenominação com os dados de sobrenome e moleculares deste trabalho concluímos que a autodenominação é um critério impreciso na avaliação da contribuição parental dentro desta população. Este tipo de trabalho pode auxiliar estudos de associação entre fatores de saúde com a heterogeneidade ancestral para melhoria e/ou implantação de programas de saúde pública que considerem a composição parental desta população. / Native American, Africans and Europeans are the major founder populations of Brazil and of Salvador city. Brazilian population is considered as the most heterogeneous in the world, resulting from 5 centuries of miscegenation. However, ethnic ancestral groups were not distributed equally in the different Brazilian regions. In addition, a strong bias occurred originated by more frequent unions among European men and Amerindians and Africans women. Results from IBGE 2000 show that in Salvador the percent of selfclassification afrodescending, is 79.8 %. To estimate the contribution of ancestral groups in these populations we analyzed some population specific alleles: AT3-I/D, APO, SB19.3, PV92, FYnull, LPL, CKMM, GC and CYP3A4 from 1,286 subjects of Salvador that presents large frequency differential among ancestry groups. To estimate the African origin of the subjects we also analyzed the religious connotation surnames. We identified 287 surnames in these populations. In Salvador population, the frequency of religious connotation surnames was 54. 9% and we observed an inverse relation between socioeconomic status and the presence of this type of surname. These data were confirmed for a major African genomic ancestry (53. 1%) between individuals that present religious connotation surname. The miscegenation of Salvador was confirmed by the frequencies differences in this population with the ancestry, such as the population admixture esteemed, with African contribution of 49.2%; 36.3% European and 14.5% Amerindian and also by heterozygosis mediam analyses (0,397) and populational structure. F statistic (0,005) was calculated and showed differences between regions in the city, but in little proportions, confirming the admixture estimated in these regions. When we compared IBGE- 2000 African contribution esteemed, by autodenomination, with the surnames and molecular data of this work we concluded that autodenomination is an inaccurate criterion to evaluate the parental contribution into this population. This kind of work can support association studies among health factors with ancestry heterogeneity to improve and/or to implement public health programs that consider the parental composition of this population.