Photodynamic inactivation of bacteria by cationic porphyrins : their cellular targets and potential environmental applications

Photodynamic inactivation (PDI) is defined as the process of cell destruction by oxidative stress resulting from the interaction between light and a photosensitizer (PS), in the presence of molecular oxygen. PDI of bacteria has been extensively studied in recent years, proving to be a promising alternative to conventional antimicrobial agents for the treatment of superficial and localized infections. Moreover, the applicability of PDI goes far beyond the clinical field, as its potential use in water disinfection, using PS immobilized on solid supports, is currently under study. The aim of the first part of this work was to study the oxidative modifications in phospholipids, nucleic acids and proteins of Escherichia coli and Staphylococcus warneri, subjected to photodynamic treatment with cationic porphyrins. The aims of the second part of the work were to study the efficiency of PDI in aquaculture water and the influence of different physicalchemical parameters in this process, using the Gram-negative bioluminescent bacterium Vibrio fischeri, and to evaluate the possibility of recycling cationic PS immobilized on magnetic nanoparticles. To study the oxidative changes in membrane phospholipids, a lipidomic approach has been used, combining chromatographic techniques and mass spectrometry. The FOX2 assay was used to determine the concentration of lipid hydroperoxides generated after treatment. The oxidative modifications in the proteins were analyzed by one-dimensional polyacrylamide gel electrophoresis (SDS-PAGE). Changes in the intracellular nucleic acids were analyzed by agarose gel electrophoresis and the concentration of doublestranded DNA was determined by fluorimetry. The oxidative changes of bacterial PDI at the molecular level were analyzed by infrared spectroscopy. In laboratory tests, bacteria (108 CFU mL-1) were irradiated with white light (4.0 mW cm-2) after incubation with the PS (Tri-Py+-Me-PF or Tetra-Py+-Me) at concentrations of 0.5 and 5.0 μM for S. warneri and E. coli, respectively. Bacteria were irradiated with different light doses (up to 9.6 J cm-2 for S. warneri and up to 64.8 J cm-2 for E. coli) and the changes were evaluated throughout the irradiation time. In the study of phospholipids, only the porphyrin Tri-Py+-Me-PF and a light dose of 64.8 J cm-2 were tested. The efficiency of PDI in aquaculture has been evaluated in two different conditions: in buffer solution, varying temperature, pH, salinity and oxygen concentration, and in aquaculture water samples, to reproduce the conditions of PDI in situ. The kinetics of the process was determined in realtime during the experiments by measuring the bioluminescence of V. fischeri (107 CFU mL-1, corresponding to a level of bioluminescence of 105 relative light units). A concentration of 5.0 μM of Tri-Py+-Me-PF was used in the experiments with buffer solution, and 10 to 50 μM in the experiments with aquaculture water. Artificial white light (4.0 mW cm-2) and solar irradiation (40 mW cm-2) were used as light sources.

Microbe-mediated recovery of salt marshes contaminated with oil hydrocarbons

Salt marshes are highly productive intertidal habitats that serve as nursery grounds for many commercially and economically important species. Because of their location and physical and biological characteristics, salt marshes are considered to be particularly vulnerable to anthropogenic inputs of oil hydrocarbons. Sediment contamination with oil is especially dangerous for salt marsh vegetation, since low molecular weight aromatic hydrocarbons can affect plants at all stages of development. However, the use of vegetation for bioremediation (phytoremediation), by removal or sequestration of contaminants, has been intensively studied. Phytoremediation is an efficient, inexpensive and environmental friendly approach for the removal of aromatic hydrocarbons, through direct incorporation by the plant and by the intervention of degrading microbial populations in the rhizosphere (microbe-assisted phytoremediation). Rhizosphere microbial communities are enriched in important catabolic genotypes for degradation of oil hydrocarbons (OH) which may have a potential for detoxification of the sediment surrounding the roots. In addition, since rhizosphere bacterial populations may also internalize into plant tissues (endophytes), rhizocompetent AH degrading populations may be important for in planta AH degradation and detoxification. The present study involved field work and microcosms experiments aiming the characterization of relevant plant-microbe interactions in oilimpacted salt marshes and the understanding of the effect of rhizosphere and endosphere bacteria in the role of salt marsh plants as potential phytoremediation agents. In the field approach, molecular tools were used to assess how plant species- and OH pollution affect sediment bacterial composition [bulk sediment and sediment surrounding the roots (rhizosphere) of Halimione portulacoides and Sarcocornia perennis subsp. perennis] in a temperate estuary (Ria de Aveiro, Portugal) chronically exposed to OH pollution. In addition, the 16S rRNA gene sequences retrieved in this study were used to generate in silico metagenomes and to evaluate the distribution of potential bacterial traits in different microhabitats. Moreover, a combination of culture-dependent and -independent approaches was used to investigate the effect of oil hydrocarbons contamination on the structure and function of endophytic bacterial communities of salt marsh plants.Root systems of H. portulacoides and S. perennis subsp. perennis appear to be able to exert a strong influence on bacterial composition and in silico metagenome analysis showed enrichment of genes involved in the process of polycyclic aromatic hydrocarbon (PAH) degradation in the rhizosphere of halophyte plants. The culturable fraction of endophytic degraders was essentially closely related to known OH-degrading Pseudomonas species and endophytic communities revealed sitespecific effects related to the level of OH contamination in the sediment. In order to determine the effects of oil contamination on plant condition and on the responses in terms of structure and function of the bacterial community associated with plant roots (rhizosphere, endosphere), a microcosms approach was set up. The salt marsh plant Halimione portulacoides was inoculated with a previous isolated Pseudomonas sp. endophytic degrader and the 2-methylnaphthalene was used as model PAH contaminant. The results showed that H. portulacoides health and growth were not affected by the contamination with the tested concentration. Moreover, the decrease of 2-methylnaphthalene at the end of experiment, can suggest that H. portulacoides can be considered as a potential plant for future uses in phytoremedition approaches of contaminated salt marsh. The acceleration of hydrocarbon degradation by inoculation of the plants with the hydrocarbon-degrading Pseudomonas sp. could not, however, be demonstrated, although the effects of inoculation on the structure of the endophytic community observed at the end of the experiment indicate that the strain may be an efficient colonizer of H. portulacoides roots. The results obtained in this work suggest that H. portulacoides tolerates moderate concentrations of 2-methylnaphthalene and can be regarded as a promising agent for phytoremedition approaches in salt marshes contaminated with oil hydrocarbons. Plant/microbe interactions may have an important role in the degradation process, as plants support a diverse endophytic bacterial community, enriched in genetic factors (genes and plasmids) for hydrocarbon degradation.

Various Joyful Encounters with the Dystopias of Affective Capitalism

This article contends that what appear to be the dystopic conditions of affective capitalism are just as likely to be felt in various joyful encounters as they are in atmospheres of fear associated with post 9/11 securitization. Moreover, rather than grasping these joyful encounters with capitalism as an ideological trick working directly on cognitive systems of belief, they are approached here by way of a repressive affective relation a population establishes between politicized sensory environments and what Deleuze and Guattari (1994) call a brain-becoming-subject. This is a radical relationality (Protevi, 2010) understood in this context as a mostly nonconscious brain-somatic process of subjectification occurring in contagious sensory environments populations become politically situated in. The joyful encounter is not therefore merely an ideological manipulation of belief, but following Gabriel Tarde (as developed in Sampson, 2012), belief is always the object of desire. The discussion starts by comparing recent efforts by Facebook to manipulate mass emotional contagion to a Huxleyesque control through appeals to joy. Attention is then turned toward further manifestations of affective capitalism; beginning with the so-called emotional turn in the neurosciences, which has greatly influenced marketing strategies intended to unconsciously influence consumer mood (and choice), and ending with a further comparison between encounters with Nazi joy in the 1930s (Protevi, 2010) and the recent spreading of right wing populism similarly loaded with political affect. Indeed, the dystopian presence of a repressive political affect in all of these examples prompts an initial question concerning what can be done to a brain so that it involuntarily conforms to the joyful encounter. That is to say, what can affect theory say about an apparent brain-somatic vulnerability to affective suggestibility and a tendency toward mass repression? However, the paper goes on to frame a second (and perhaps more significant) question concerning what can a brain do. Through the work of John Protevi (in Hauptmann and Neidich (eds.), 2010: 168-183), Catherine Malabou (2009) and Christian Borch (2005), the article discusses how affect theory can conceive of a brain-somatic relation to sensory environments that might be freed from its coincidence with capitalism. This second question not only leads to a different kind of illusion to that understood as a product of an ideological trick, but also abnegates a model of the brain which limits subjectivity in the making to a phenomenological inner self or Being in the world.

Structural and chemical characterization of corals grown under present day and naturally elevated pCO2 conditions in Papua New Guinea - a window into the future

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Influence of the North Atlantic Oscillation on Grass Pollen Counts in Europe

Relationships between temporal variations in the North Atlantic Oscillation (NAO) and grass pollen counts at 13 sites in Europe, ranging from Córdoba in the South-West and Turku in the North-East, were studied in order to determine spatial differences in the amount of influence exerted by the NAO on the timing and magnitude of grass pollen seasons. There were a number of significant (p<0.05) relationships between the NAO and start dates of the grass pollen season at the 13 pollen-monitoring sites. The strongest associations were generally recorded near to the Atlantic coast. Several significant correlations also existed between winter averages of the NAO and grass pollen season severity. Traditional methods for predicting the start or magnitude of grass pollen seasons have centred on the use of local meteorological observations, but this study has shown the importance of considering large-scale patterns of climate variability like the NAO.

The influence of water column variability and seafloor topography on multibeam bathymetric mapping

Senior thesis written for Oceanography 445

The impact of safety politics in the current globalization context

The globalization is a process of economical, social, cultural and political integration motivated by the needs generated by a consumption-orientated society and a set of factors that have led to its development, such as reducing transport costs, the technological advancement and the development of communication networks. However, the phenomenon of globalization has been accompanied by increasing levels of insecurity as a result of various types of threats and transnational crimes that the International Community seeks to control and minimize. Throughout this work, we examined how the globalization process has been developing and how nations are able to maintain security levels consistent with their economical status and social development, without disturbing the normal course of organizations’ economical activity and the well-being of people. From the investigation developed we concluded that, besides the confirmation that economic integration and the opening of markets have influence on internal consumption, market globalization and migrations have been causing modifications in the consumption habits. We also concluded that the security measures implemented by States or by the International Community affect international trade, but do not imply disproportionate costs or significant delays in transactions. Likewise, we concluded that the control measures implemented in international trade are sufficient to ensure the safety of the people and nations, enabling us to confirm two of the three conjectures raised in this study.

Optimization of the Pultrusion process

Manufacturing processes need permanently to innovate and optimize because any can be susceptible to continuous improvement. Innovation and commitment to the development of these new solutions resulting from existing expertise and the continuing need to increase productivity, flexibility and ensuring the necessary quality of the manufactured products. To increase flexibility, it is necessary to significantly reduce set-up times and lead time in order to ensure the delivery of products ever faster. This objective can be achieved through a normalization of the pultrusion line elements. Implicitly, there is an increase of productivity by this way. This work is intended to optimize the pultrusion process of structural profiles. We consider all elements of the system from the storehouse of the fibers (rack) to the pultrusion die. Particular attention was devoted to (a) the guidance system of the fibers and webs, (b) the resin container where the fibers are impregnated, (c) standard plates positioning of the fibers towards the entrance to the spinneret and also (d) reviewed the whole process of assembling and fixing the die as well as its the heating system. With the implementation of these new systems was achieved a significant saving of time set-up and were clearly reduced the unit costs of production. Quality assurance was also increased.