Mind the gap: characterization of periplasmic cytochromes from Shewanella oneidensis involved in extracellular electron transfer

Dissertation presented to obtain the Ph.D degree in Biochemistry

Molecular tools to dissect the role of Dmrt2a and Dmrt2b in the left-right axis formation in zebrafish

Dissertação para obtenção do Grau de Mestre em Genética Molecular e Biomedicina

Influence of Schistosoma mansoni infection on the reproductive capacity of albino mice

This paper reports reduction on the reproductive capacity of female mice infected with Schistosoma mansoni, either in the acute phase or in the chronic one of the disease. This decrease in the reproductive capacity was highly significant (93.3% and 86.7%, for the acute and chronic phases, respectively)..

Follow the red road of triheme cytochromes in Geobacter sulfurreducens

The bacterium Geobacter sulfurreducens (Gs) is capable of oxidizing a large variety of compounds relaying electrons out of the cytoplasm and across the membrane in a process designated as extracellular electron transfer. The Gs genome was fully sequenced and a family composed by five periplasmic triheme cytochromes c7 (designated PpcA-E) was identified. These cytochromes play an important role in the reduction of extracellular acceptors. They contain approximately 70 amino acids, three heme groups with bis-histidinyl axial coordination, and share between 57 and 77% sequence identity. The triheme cytochrome PpcA is highly abundant in Gs and is most likely the reservoir of electrons destined for outer surface. In addition to its role in electron transfer pathways this protein can perform e-/H+ energy transduction, a process that is disrupted when the strictly conserved aromatic residue phenylalanine 15 is replaced by a leucine (PpcAF15L). This Thesis focuses on the expression, purification and characterization of these proteins using Nuclear Magnetic Resonance and ultraviolet-visible spectroscopy. The orientations of the heme axial histidine ring planes and the orientation of the heme magnetic axis were determined for each Gs triheme cytochrome. The comparison of the orientations obtained in solution with the crystal structures available showed significant differences. The results obtained provide the paramagnetic constraints to include in the future refinement of the solution structure in the oxidized state. In this work was also determined the solution structure and the pH-dependent conformational changes of the PpcAF15L allowing infer the structural origin for e-/H+ energy transduction mechanism as shown by PpcA. Finally, the backbone and side chain NH signals of PpcA were used to map interactions between this protein and the putative redox partner 9,10-anthraquinone-2,6-disulfonate (AQDS). In this work a molecular interaction was identified for the first time between PpcA and AQDS, constituting the first step toward the rationalization of the Gs respiratory chain.

Earthen plasters: the potential of the clayey soils of barrocal region in Algarve

Due to their high adsorption capacity of water vapor, earthen plasters can act as a moisture buffer, contributing to balance the relative humidity of the indoor environment of buildings. As a consequence of this capacity earthen plasters may also contribute to the perception of thermal comfort, since a high relative humidity increases the thermal conductivity of air and restricts skin evaporation, increasing the discomfort associated with the perception of heat or cold. Simultaneously, earthen plasters may also contribute to the indoor air quality. In one hand, by mitigating health problems of the respiratory system associated with indoor environment with high relative humidity, in which increases the risk of development of microorganisms usually responsible for infections, allergies or asthma. In the other hand, by mitigating the probability of inflammation of the respiratory system airways associated to exceedingly dry indoor environments. Therefore it also becomes expectable that earthen plasters may contribute for reducing the needs for air conditioning and mechanical ventilation in buildings and, thereby, also allowing the reduction of the associated energy consumption. The «Barrocal» region, located in the sedimentary basin of Algarve, South Portugal, presents geomorphological characteristics that promote the occurrence of soils with a clay mineralogy dominated by illite, which is a clay mineral characterized by a high adsorption capacity of water vapor and low expansibility. This fact turns expectable that these soils have a high potential for interior plastering. In order to evaluate this potential four mortars were formulated with an increasing content of clayey soil extracted from a selected clay quarry from «Barrocal» region. The results from the preliminary characterization campaign confirmed the reduced linear shrinkage of these mortars, as well as their high adsorption-desorption capacity, that is positively correlated with the content of clayey soil present in mortar formulation. However, the mechanical tests showed that the mechanical resistance of these mortars should be improved, for instance through the addition of natural fibers for reinforcement, which will be investigated in future research. This research contributed to increase certainty regarding the potential of clayey soils of the «Barrocal» sub-region of Algarve to produce mortars suitable for eco-efficient interior plastering.

Epidemiological pattern of leprosy in an endemic area of North-East Brazil, 1996-2005: the supporting role of a Nongovernmental Organization

In an endemic area of North-East Brazil (the town of Picos, State of Piauí), a nongovernmental organization (NGO) supported the activity against leprosy in connection with governmental health organizations and local agents. The indicators of leprosy elimination were compared over time (within Picos) and across space (Picos versus Piauí). The case detection rate, above 8 per 10,000 people in the last two years of observation, increased over time in Picos (p=0.010). This finding could be due to active detection activities rather than expanding endemicity, as suggested by the reduction in leprosy in children (p=0.053) and the decrease in the proportion of new cases with grade 2 disability (p<0.001). These indicators showed a more favorable time trend in the city than in the State, suggesting that NGO activity was supportive in the battle towards leprosy control.

Vertical transmission of HIV-1 in the western region of the State of São Paulo

INTRODUCTION: This study aimed to determine the prevalence of vertical HIV-1 transmission in the western region of the State of São Paulo, Brazil. METHODS: The study analyzed the medical records of HIV-1-infected mothers and infant pairs living in the municipalities of São Paulo Regional Health Departments DRS II (Araçatuba) and DRS XI (Presidente Prudente). From March 2001 to March 2006, blood samples were collected and referred to the Molecular Biology Unit of the Adolfo Lutz Institute (ALI), Presidente Prudente. HIV-1-RNA viral load was determined by bDNA assay. RESULTS: The number of births (109/217, 50.2%) and vertical HIV-1 transmissions (6/109, 5.5%) that occurred in DRS II was similar to births (108/217, 49.8%) and vertical transmissions (7/108, 6.5%) in DRS XI (p > 0.05). Although 80% (4/5) of the infected children were male in DRS II, while in DRS XI, 75% (6/8) were female, no differences between sex regarding infected and noninfected children in the regions of Araçatuba and Presidente Prudente were verified. The overall vertical HIV-1 transmission rate was 6%. No consistent reduction in the prevalence of vertical HIV-1 transmission occurred over the years. About 20% of mothers did not know the HIV-1 status of their newborns eight months after delivery. CONCLUSIONS: In the present study, MTCT prevalence rates were about 70% higher than those previously determined in the State of São Paulo, with noreduction throughout the period.Furthermore, a significant number of mothers did not know the HIV-status of their newborns eight months after delivery.

Reduction of catheter-associated bloodstream infections through procedures in newborn babies admitted in a university hospital intensive care unit in Brazil

INTRODUCTION: Catheter-associated bloodstream infection (CA-BSI) is the most common nosocomial infection in neonatal intensive care units. There is evidence that care bundles to reduce CA-BSI are effective in the adult literature. The aim of this study was to reduce CA-BSI in a Brazilian neonatal intensive care unit by means of a care bundle including few strategies or procedures of prevention and control of these infections. METHODS: An intervention designed to reduce CA-BSI with five evidence-based procedures was conducted. RESULTS: A total of sixty-seven (26.7%) CA-BSIs were observed. There were 46 (32%) episodes of culture-proven sepsis in group preintervention (24.1 per 1,000 catheter days [CVC days]). Neonates in the group after implementation of the intervention had 21 (19.6%) episodes of CA-BSI (14.9 per 1,000 CVC days). The incidence of CA-BSI decreased significantly after the intervention from the group preintervention and postintervention (32% to 19.6%, 24.1 per 1,000 CVC days to 14.9 per 1,000 CVC days, p=0.04). In the multiple logistic regression analysis, the use of more than 3 antibiotics and length of stay >8 days were independent risk factors for BSI. CONCLUSIONS: A stepwise introduction of evidence-based intervention and intensive and continuous education of all healthcare workers are effective in reducing CA-BSI.

Evaluation of the welfare impact of regulating mobile termination rates in Portugal

Following the European Commission’s 2009 Recommendation on the Regulatory Treatment of Fixed and Mobile Termination Rates in the EU, the Portuguese regulatory authority (ANACOM) decided to reduce termination prices in mobile networks to their long-run incremental cost (LRIC). Nevertheless, no serious quantitative assessment of the potential effects of this decision was carried out. In this paper, we adapt and calibrate the Harbord and Hoernig (2014) model of the UK mobile telephony market to the Portuguese reality, and simulate the likely impact on consumer surplus, profits and welfare of four different regulatory approaches: pure LRIC, reciprocal termination charges with fixed networks, “bill & keep”, and asymmetric termination rates. Our results show that reducing MTRs does increase social welfare, profits and consumer surplus in the fixed market, but mobile subscribers are seriously harmed by this decision.

Serologic assessment of yellow fever immunity in the rural population of a yellow fever-endemic area in Central Brazil

IntroductionThe yellow fever epidemic that occurred in 1972/73 in Central Brazil surprised the majority of the population unprotected. A clinical-epidemiological survey conducted at that time in the rural area of 19 municipalities found that the highest (13.8%) number of disease cases were present in the municipality of Luziânia, State of Goiás.MethodsThirty-eight years later, a new seroepidemiological survey was conducted with the aim of assessing the degree of immune protection of the rural population of Luziânia, following the continuous attempts of public health services to obtain vaccination coverage in the region. A total of 383 volunteers, aged between 5 and 89 years and with predominant rural labor activities (75.5%), were interviewed. The presence of antibodies against the yellow fever was also investigated in these individuals, by using plaque reduction neutralization test, and correlated to information regarding residency, occupation, epidemiological data and immunity against the yellow fever virus.ResultsWe found a high (97.6%) frequency of protective titers (>1:10) of neutralizing antibodies against the yellow fever virus; the frequency of titers of 1:640 or higher was 23.2%, indicating wide immune protection against the disease in the study population. The presence of protective immunity was correlated to increasing age.ConclusionsThis study reinforces the importance of surveys to address the immune state of a population at risk for yellow fever infection and to the surveillance of actions to control the disease in endemic areas.

Impact of insecticide resistance on the field control of Aedes aegypti in the State of São Paulo

IntroductionThe need to control dengue transmission by means of insecticides has led to the development of resistance to most of the products used worldwide against mosquitoes. In the State of São Paulo, the Superintendência de Controle de Endemias(SUCEN) has annually monitored the susceptibility of Aedes aegypti to insecticides since 1996; since 1999, surveys were conducted in collaboration with the National Network of Laboratories (MoReNAa Network) and were coordinated by the Ministry of Health. In this study, in addition to the biological characterization of insecticide resistance in the laboratory, the impact of resistance on field control was evaluated for vector populations that showed resistance in laboratory assays.MethodsField efficacy tests with larvicides and adulticides were performed over a 13-year period, using World Health Organization protocols.ResultsData from the field tests showed a reduction in the residual effect of temephos on populations with a resistance ratio of 3. For adults, field control was less effective in populations characterized as resistant in laboratory qualitative assays, and this was confirmed using qualitative assays and field evaluation.ConclusionsOur results indicated that management of resistance development needs to be adopted when insect populations show reduced susceptibility. The use of insecticides is a self-limiting tool that needs to be applied cautiously, and dengue control requires more sustainable strategies.

The residual effect of deltametrine in the control of Malaria as observed on fifferent types Of walls In the Brazilian Amazon 1

The residual power of deltametrine FW (25 mg 1 .a/m2) was evaluated and compared to that of DDT (2 g i.a./m2) by means of biological tests. The different kinds of material used in constructing houses in Amazonia, such as: masonry, wood, and wattle and daub, were used. Data from logistic regression showed that the drop in mortality, the inclination of the curve in relation to time, was similar for the two insecticides in the first samples. The negative coeficient for the variable, months after application, confirmed a reduction in the activity of both insecticides. Wooden and wattle walls showed positive and negative coeficiencies respectively from the beginning. The wooden walls retained a residual effect but the wattle walls were shown to be the least indicated for the application of insecticides The experiments demonstrated a more prolonged residual effect for deltametrine as compared to DDT, and that insecticides work better on brick and cement and wooden walls than they do on wattle and daub constructions. For these reasons, it would be necessary to spray brick and cement walls every 8 months, wooden ones every 9 months and wattle constructions every 7 months to control the vectors of malaria.

The trading relationship between the EU and Mercosur: the mediatory role of Brazil

Dissertação de mestrado em European and Transglobal Business Law

Carbon materials as new generation of new electron shuttles for the anaerobic degradation of environmental xenobiotics

Tese de Doutoramento em Engenharia Química e Biológica

Evolution of the gene regulatory network controlling flower dorsoventral asymmetry

Tese de Doutoramento em Biologia de Plantas.