Interference with Hemozoin Formation Represents an Important Mechanism of Schistosomicidal Action of Antimalarial Quinoline Methanols

Background: The parasitic trematode Schistosoma mansoni is one of the major causative agents of human schistosomiasis, which afflicts 200 million people worldwide. Praziquantel remains the main drug used for schistosomiasis treatment, and reliance on the single therapy has been prompting the search for new therapeutic compounds against this disease. Our group has demonstrated that heme crystallization into hemozoin (Hz) within the S. mansoni gut is a major heme detoxification route with lipid droplets involved in this process and acting as a potential chemotherapeutical target. In the present work, we investigated the effects of three antimalarial compounds, quinine (QN), quinidine (QND) and quinacrine (QCR) in a murine schistosomiasis model by using a combination of biochemical, cell biology and molecular biology approaches. Methodology/Principal Findings: Treatment of S. mansoni-infected female Swiss mice with daily intraperitoneal injections of QN, and QND (75 mg/kg/day) from the 11(th) to 17(th) day after infection caused significant decreases in worm burden (39%-61%) and egg production (42%-98%). Hz formation was significantly inhibited (40%-65%) in female worms recovered from QN- and QND-treated mice and correlated with reduction in the female worm burden. We also observed that QN treatment promoted remarkable ultrastructural changes in male and female worms, particularly in the gut epithelium and reduced the granulomatous reaction to parasite eggs trapped in the liver. Microarray gene expression analysis indicated that QN treatment increased the expression of transcripts related to musculature, protein synthesis and repair mechanisms. Conclusions: The overall significant reduction in several disease burden parameters by the antimalarial quinoline methanols indicates that interference with Hz formation in S. mansoni represents an important mechanism of schistosomicidal action of these compounds and points out the heme crystallization process as a valid chemotherapeutic target to treat schistosomiasis.

The Essential Nucleolar Yeast Protein Nop8p Controls the Exosome Function during 60S Ribosomal Subunit Maturation

The yeast nucleolar protein Nop8p has previously been shown to interact with Nip7p and to be required for 60S ribosomal subunit formation. Although depletion of Nop8p in yeast cells leads to premature degradation of rRNAs, the biochemical mechanism responsible for this phenotype is still not known. In this work, we show that the Nop8p amino-terminal region mediates interaction with the 5.8S rRNA, while its carboxyl-terminal portion interacts with Nip7p and can partially complement the growth defect of the conditional mutant strain Dnop8/GAL:NOP8. Interestingly, Nop8p mediates association of Nip7p to pre-ribosomal particles. Nop8p also interacts with the exosome subunit Rrp6p and inhibits the complex activity in vitro, suggesting that the decrease in 60S ribosomal subunit levels detected upon depletion of Nop8p may result from degradation of pre-rRNAs by the exosome. These results strongly indicate that Nop8p may control the exosome function during pre-rRNA processing.

Schistosoma mansoni Tegument Protein Sm29 Is Able to Induce a Th1-Type of Immune Response and Protection against Parasite Infection

Background: Schistosomiasis continues to be a significant public health problem. This disease affects 200 million people worldwide and almost 800 million people are at risk of acquiring the infection. Although vaccine development against this disease has experienced more failures than successes, encouraging results have recently been obtained using membrane-spanning protein antigens from the tegument of Schistosoma mansoni. Our group recently identified Sm29, another antigen that is present at the adult worm tegument surface. In this study, we investigated murine cellular immune responses to recombinant (r) Sm29 and tested this protein as a vaccine candidate. Methods and Findings: We first show that Sm29 is located on the surface of adult worms and lung-stage schistosomula through confocal microscopy. Next, immunization of mice with rSm29 engendered 51%, 60% and 50% reduction in adult worm burdens, in intestinal eggs and in liver granuloma counts, respectively (p<0.05). Protective immunity in mice was associated with high titers of specific anti-Sm29 IgG1 and IgG2a and elevated production of IFN-gamma, TNF-alpha and IL-12, a typical Th1 response. Gene expression analysis of worms recovered from rSm29 vaccinated mice relative to worms from control mice revealed a significant (q<0.01) down-regulation of 495 genes and up-regulation of only 22 genes. Among down-regulated genes, many of them encode surface antigens and proteins associated with immune signals, suggesting that under immune attack schistosomes reduce the expression of critical surface proteins. Conclusion: This study demonstrates that Sm29 surface protein is a new vaccine candidate against schistosomiasis and suggests that Sm29 vaccination associated with other protective critical surface antigens is the next logical strategy for improving protection.

Genome-Wide Detection of Serpentine Receptor-Like Proteins in Malaria Parasites

Serpentine receptors comprise a large family of membrane receptors distributed over diverse organisms, such as bacteria, fungi, plants and all metazoans. However, the presence of serpentine receptors in protozoan parasites is largely unknown so far. In the present study we performed a genome-wide search for proteins containing seven transmembrane domains (7TM) in the human malaria parasite Plasmodium falciparum and identified four serpentine receptor-like proteins. These proteins, denoted PfSR1, PfSR10, PfSR12 and PfSR25, show membrane topologies that resemble those exhibited by members belonging to different families of serpentine receptors. Expression of the pfsrs genes was detected by Real Time PCR in P. falciparum intraerythrocytic stages, indicating that they potentially code for functional proteins. We also found corresponding homologues for the PfSRs in five other Plasmodium species, two primate and three rodent parasites. PfSR10 and 25 are the most conserved receptors among the different species, while PfSR1 and 12 are more divergent. Interestingly, we found that PfSR10 and PfSR12 possess similarity to orphan serpentine receptors of other organisms. The identification of potential parasite membrane receptors raises a new perspective for essential aspects of malaria parasite host cell infection.

Retinoic Acid-Treated Pluripotent Stem Cells Undergoing Neurogenesis Present Increased Aneuploidy and Micronuclei Formation

The existence of loss and gain of chromosomes, known as aneuploidy, has been previously described within the central nervous system. During development, at least one-third of neural progenitor cells (NPCs) are aneuploid. Notably, aneuploid NPCs may survive and functionally integrate into the mature neural circuitry. Given the unanswered significance of this phenomenon, we tested the hypothesis that neural differentiation induced by all-trans retinoic acid (RA) in pluripotent stem cells is accompanied by increased levels of aneuploidy, as previously described for cortical NPCs in vivo. In this work we used embryonal carcinoma (EC) cells, embryonic stem (ES) cells and induced pluripotent stem (iPS) cells undergoing differentiation into NPCs. Ploidy analysis revealed a 2-fold increase in the rate of aneuploidy, with the prevalence of chromosome loss in RA primed stem cells when compared to naive cells. In an attempt to understand the basis of neurogenic aneuploidy, micronuclei formation and survivin expression was assessed in pluripotent stem cells exposed to RA. RA increased micronuclei occurrence by almost 2-fold while decreased survivin expression by 50%, indicating possible mechanisms by which stem cells lose their chromosomes during neural differentiation. DNA fragmentation analysis demonstrated no increase in apoptosis on embryoid bodies treated with RA, indicating that cell death is not the mandatory fate of aneuploid NPCs derived from pluripotent cells. In order to exclude that the increase in aneuploidy was a spurious consequence of RA treatment, not related to neurogenesis, mouse embryonic fibroblasts were treated with RA under the same conditions and no alterations in chromosome gain or loss were observed. These findings indicate a correlation amongst neural differentiation, aneuploidy, micronuclei formation and survivin downregulation in pluripotent stem cells exposed to RA, providing evidence that somatically generated chromosomal variation accompanies neurogenesis in vitro.

A Component of the Xanthomonadaceae Type IV Secretion System Combines a VirB7 Motif with a N0 Domain Found in Outer Membrane Transport Proteins

Type IV secretion systems (T4SS) are used by Gram-negative bacteria to translocate protein and DNA substrates across the cell envelope and into target cells. Translocation across the outer membrane is achieved via a ringed tetradecameric outer membrane complex made up of a small VirB7 lipoprotein (normally 30 to 45 residues in the mature form) and the C-terminal domains of the VirB9 and VirB10 subunits. Several species from the genera of Xanthomonas phytopathogens possess an uncharacterized type IV secretion system with some distinguishing features, one of which is an unusually large VirB7 subunit (118 residues in the mature form). Here, we report the NMR and 1.0 angstrom X-ray structures of the VirB7 subunit from Xanthomonas citri subsp. citri (VirB7(XAC2622)) and its interaction with VirB9. NMR solution studies show that residues 27-41 of the disordered flexible N-terminal region of VirB7(XAC2622) interact specifically with the VirB9 C-terminal domain, resulting in a significant reduction in the conformational freedom of both regions. VirB7(XAC2622) has a unique C-terminal domain whose topology is strikingly similar to that of N0 domains found in proteins from different systems involved in transport across the bacterial outer membrane. We show that VirB7(XAC2622) oligomerizes through interactions involving conserved residues in the N0 domain and residues 42-49 within the flexible N-terminal region and that these homotropic interactions can persist in the presence of heterotropic interactions with VirB9. Finally, we propose that VirB(7XAC2622) oligomerization is compatible with the core complex structure in a manner such that the N0 domains form an extra layer on the perimeter of the tetradecameric ring.

Mild Mitochondrial Uncoupling and Calorie Restriction Increase Fasting eNOS, Akt and Mitochondrial Biogenesis

Enhanced mitochondrial biogenesis promoted by eNOS activation is believed to play a central role in the beneficial effects of calorie restriction (CR). Since treatment of mice with dinitrophenol (DNP) promotes health and lifespan benefits similar to those observed in CR, we hypothesized that it could also impact biogenesis. We found that DNP and CR increase citrate synthase activity, PGC-1 alpha, cytochrome c oxidase and mitofusin-2 expression, as well as fasting plasma levels of NO(center dot) products. In addition, eNOS and Akt phosphorylation in skeletal muscle and visceral adipose tissue was activated in fasting CR and DNP animals. Overall, our results indicate that systemic mild uncoupling activates eNOS and Akt-dependent pathways leading to mitochondrial biogenesis.

Structure-Function Analysis of the HrpB2-HrcU Interaction in the Xanthomonas citri Type III Secretion System

Bacterial type III secretion systems deliver protein virulence factors to host cells. Here we characterize the interaction between HrpB2, a small protein secreted by the Xanthomonas citri subsp. citri type III secretion system, and the cytosolic domain of the inner membrane protein HrcU, a paralog of the flagellar protein FlhB. We show that a recombinant fragment corresponding to the C-terminal cytosolic domain of HrcU produced in E. coli suffers cleavage within a conserved Asn264-Pro265-Thr266-His267 (NPTH) sequence. A recombinant HrcU cytosolic domain with N264A, P265A, T266A mutations at the cleavage site (HrcU(AAAH)) was not cleaved and interacted with HrpB2. Furthermore, a polypeptide corresponding to the sequence following the NPTH cleavage site also interacted with HrpB2 indicating that the site for interaction is located after the NPTH site. Non-polar deletion mutants of the hrcU and hrpB2 genes resulted in a total loss of pathogenicity in susceptible citrus plants and disease symptoms could be recovered by expression of HrpB2 and HrcU from extrachromossomal plasmids. Complementation of the Delta hrcU mutant with HrcU(AAAH) produced canker lesions similar to those observed when complemented with wild-type HrcU. HrpB2 secretion however, was significantly reduced in the Delta hrcU mutant complemented with HrcU(AAAH), suggesting that an intact and cleavable NPTH site in HrcU is necessary for total functionally of T3SS in X. citri subsp. citri. Complementation of the Delta hrpB2 X. citri subsp. citri strain with a series of hrpB2 gene mutants revealed that the highly conserved HrpB2 C-terminus is essential for T3SS-dependent development of citrus canker symptoms in planta.

A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians

Advanced titanosaurian sauropods, such as nemegtosaurids and saltasaurids, were diverse and one of the most important groups of herbivores in the terrestrial biotas of the Late Cretaceous. However, little is known about their rise and diversification prior to the Late Cretaceous. Furthermore, the evolution of their highly-modified skull anatomy has been largely hindered by the scarcity of well-preserved cranial remains. A new sauropod dinosaur from the Early Cretaceous of Brazil represents the earliest advanced titanosaurian known to date, demonstrating that the initial diversification of advanced titanosaurians was well under way at least 30 million years before their known radiation in the latest Cretaceous. The new taxon also preserves the most complete skull among titanosaurians, further revealing that their low and elongated diplodocid-like skull morphology appeared much earlier than previously thought.

A religião e os limites da técnica : aproximações e distanciamentos a partir do pensamento de Jürgen Habermas

Religião e técnica, ainda que em momentos e pesos distintos na arquitetônica do pensamento de Jürgen Habermas, acabam por se constituir como temas dialogais referenciais na obra de tal autor, a partir dos quais estrutura seu pensamento em um crescendo teórico que se estende desde seus primeiros ensaios até seus mais recentes escritos. O objetivo desta dissertação é, a partir de uma revisão bibliográfica, analisar as aproximações encetadas por Habermas acerca destes pólos dialogais explicitando movimentos e aportes teóricos elaborados em cada etapa. Propomo-nos a trabalhar em um primeiro momento o conceito de técnica explicitando a influência herdada da Escola de Frankfurt, bem como suas reconstruções e propostas aos impactos de uma razão instrumentalizada na sociedade. O ponto culminante da análise habermasiana acerca do conhecimento tecnocientífico será o delineamento dos limites ético-normativos de tais conhecimentos e ao mesmo tempo a exposição das patologias e insuficiências de uma razão estratégica, ou unicamente relacionada a fins, o que culmina com sua proposta de um “naturalismo mitigado”. A partir deste horizonte teórico trabalharemos o conceito de religião e sua importância no marco teórico hodierno de Habermas. Por fim, analisamos sua aproximação ao conceito de religião e a importância deste movimento na guinada interpretativa acerca desta, culminando com sua reposição no interior do pensamento de tal autor.

Mediação: Confiança versus Responsabilidade

A mediação aparece inserida num movimento de reformas do sistema judiciário europeu como forma de responder imediatamente á descrença dos cidadãos nas estruturas do poder judicial e na eficiência da justiça. A mediação, per si, coloca a questão do elenco da confiança e da responsabilidade entre duas pessoas, como conceito define-se justamente na relação dialógica confiança/responsabilidade que produz efeitos na esfera jurídica dos interessados, as partes que decidem resolver o litígio recorrendo á intervenção de um terceiro, o mediador. É um meio extrajudicial de resolução de litígios, com carácter privado, informal, confidencial, voluntário e de natureza não conscienciosa, na qual as partes com a sua participação activa e directa, são auxiliadas por um mediador a encontrar por si próprias, uma solução negociada e amigável para o conflito. A sua natureza não conscienciosa impõe o respeito pelos princípios da cooperação e da boa fé, com vista a alcançar, de forma concertada, resultado consensual, que satisfaça ambas as partes. Neste âmbito a confiança e a responsabilidade são os dois pólos de um meridiano denominado de mediação: por meio de- através de-chegar a um acordo. Se por um lado a confiança é um elemento constitutivo da relação fática e simples de consenso porque não se trata nenhum negocio jurídico, contrato em especial, nem mero ato jurídico- por outro lado, o mediador pode ser responsável pela falta de acordo. Mas o apuramento desta responsabilidade pode não ser visível através dos óculos de culpa grosseira vertida no artigo 16º da Portaria 1112/2005 de 28 de Outubro. Efectivamente, as partes que recorrem a este meio alternativo de resolução de litígios têm direito a esperar que o mediador cumpra a lei, mas tal pode não acontecer. Assim, o exercício da mediação é ou pode ser uma fonte de responsabilidade quando o mediador viola os seus deveres, ainda que não de forma dolorosa, intencional. Ora se o Estado quer que os cidadãos acreditem nos meios extra judiciais, confiem na mediação dos Julgados de Paz, então deve promover no sentido de dizer claramente que esta atento ao desempenho do mediador, e que se advier um dano para o cidadão, o Estado deverá assumir a responsabilidade.

Federalismo e Democracia

É necessário arranjar um sistema de governação do conjunto que respeite um equilíbrio entre os dois pólos, Dimensão (todos diferentes) e Autonomia (todos iguais). A dificuldade essencial é que a aplicação absoluta da regra democrática pode levar a uma antinomia entre Cidadania (um homem um voto) e Soberania (um Estado um voto). E sobretudo o que poderá ter sentido é, descendo das utopias de encontrar formulas de Paz perpétua, pôr os olhos críticos do Estudioso das Ciências Sociais no que é um processo fecundo de organizar a convivência política entre Grupos sócio-políticos, que se sentem e querem diferentes, mas com idêntica força o querem ser dentro de um Todo de que todos se reclamam e ao qual desejam pertencer.

Jovens, cultura popular e consumo massificado : Um estudo sobre a Festa do Rosário de Pombal

O objeto dessa pesquisa é o estudo da juventude e sua inserção ou não na cultura do consumo massificado pós-moderno no cenário histórico tradicional da Festa do Rosário, que tem mais de cem anos de existência na cidade de Pombal/PB. O problema desta investigação foi sintetizado pela seguinte pergunta: Quais são as representações simbólicas dos jovens de ensino médio a respeito da comparação entre a cultura tradicional e do consumo moderno, que vêm sendo mescladas na Festa do Rosário de Pombal/PB? Descobrimos que o consumismo foi incorporado às tradições históricas desta cidade através da prática imperativa de se medir simbolicamente a posição das pessoas pelo que elas supostamente têm e pelo que elas “podem” comprar e exibir, especialmente no decorrer das comemorações da festa do Rosário. Esta mentalidade reproduz a radiografia da sociedade de Pombal/PB, que é baseada em dois pólos, os ricos e pobres, que hoje são representados pelos que “podem” consumir e os que supostamente não têm poder aquisitivo. Em suma, as tradições deste contexto social foram traduzidas para os tempos modernos e de cultura de consumo. Os autores que inspiraram esta pesquisa foram: Gramsci (1986 e 1989), Martín-Barbero (1997), Canclini (1995), Featherstone (1995), Debord (1997), Hall (1996 e 1999), Dupas (1999), além de Seixas (2004), o historiador de Pombal, entre outros.

Necessidades de formação de professores para inclusão

A presente dissertação tem como objectivo compreender a necessidades de formação contínua de formação contínua de professores de Ensino Básico Integrado no Concelho de São Miguel ilha de Santiago tendo em vista as práticas inclusivas. Para a sua realização foi utilizada a entrevista semi-directiva aos professores do Ensino Básico Integrado do Concelho de São Miguel ilha de Santiago e aos gestores dos pólos educativos também deste Concelho. Os dados recolhidos nas entrevistas foram trabalhados através de análise de conteúdo. Os dados obtidos permitiram-nos perceber as potencialidades da técnica de entrevista na recolha de informações relativas a opiniões, percepções e perspectivas pessoais e profissionais. Com efeito, esses resultados permitiram-nos identificar preocupações, dificuldades, carências, expectativas dos professores relativamente à formação contínua de para a efectivação da educação inclusiva. Esses resultados também permitiram concluir que estas necessidades de formação não advém exclusivamente da inclusão de alunos com Necessidades Educativas Especiais no sistema regular de ensino, uma vez que todos os intervenientes no estudo revelaram que necessitam de receber sessões de formação não só para a implementação do processo inclusivo, como também para o aperfeiçoamento e desenvolvimento profissional. Portanto, a análise das informações fornecidas pelos professores e pelos gestores permitiu-nos também identificar os temas e os processos, através dos quais os inquiridos gostariam de ver as sessões de formação serem desenvolvidas, de forma a colmatar as necessidades decorrentes do exercício da sua profissão, o que nos permitiu elaborar um conjunto de propostas para a formação contínua, tendo em consideração não apenas a inclusão dos alunos com Necessidades Educativas Especiais, mas também tendo em consideração o exercício da profissão em geral.