Biochemical and spectroscopic characterization of the membrane-bound nitrate reductase from Marinobacter hydrocarbonoclasticus 617

J Biol Inorg Chem (2008) 13:1321–1333 DOI 10.1007/s00775-008-0416-1

Vulnerability of mediterranean watersheds to climate change

Desertification is a critical issue for Mediterranean drylands. Climate change is expected to aggravate its extension and severity by reinforcing the biophysical driving forces behind desertification processes: hydrology, vegetation cover and soil erosion. The main objective of this thesis is to assess the vulnerability of Mediterranean watersheds to climate change, by estimating impacts on desertification drivers and the watersheds’ resilience to them. To achieve this objective, a modeling framework capable of analyzing the processes linking climate and the main drivers is developed. The framework couples different models adapted to different spatial and temporal scales. A new model for the event scale is developed, the MEFIDIS model, with a focus on the particular processes governing Mediterranean watersheds. Model results are compared with desertification thresholds to estimate resilience. This methodology is applied to two contrasting study areas: the Guadiana and the Tejo, which currently present a semi-arid and humid climate. The main conclusions taken from this work can be summarized as follows: • hydrological processes show a high sensitivity to climate change, leading to a significant decrease in runoff and an increase in temporal variability; • vegetation processes appear to be less sensitive, with negative impacts for agricultural species and forests, and positive impacts for Mediterranean species; • changes to soil erosion processes appear to depend on the balance between changes to surface runoff and vegetation cover, itself governed by relationship between changes to temperature and rainfall; • as the magnitude of changes to climate increases, desertification thresholds are surpassed in a sequential way, starting with the watersheds’ ability to sustain current water demands and followed by the vegetation support capacity; • the most important thresholds appear to be a temperature increase of +3.5 to +4.5 ºC and a rainfall decrease of -10 to -20 %; • rainfall changes beyond this threshold could lead to severe water stress occurring even if current water uses are moderated, with droughts occurring in 1 out of 4 years; • temperature changes beyond this threshold could lead to a decrease in agricultural yield accompanied by an increase in soil erosion for croplands; • combined changes of temperature and rainfall beyond the thresholds could shift both systems towards a more arid state, leading to severe water stresses and significant changes to the support capacity for current agriculture and natural vegetation in both study areas.

Função dos músculos respiratórios em doentes com insuficiência cardíaca esquerda

Revista Portuguesa de Cardiologia, 2001; 20 (5):533-545

Mapas por microscopia de Raman caso de estudo: cerâmicas arqueológicas portuguesas da idade do ferro provenientes do Castro de Azougada

Dissertação de Mestrado em Conservação e Restauro área de Especialização de Cerâmica e Vidro

Arte romana e pedreiras de mármore na Lusitânia: novos caminhos de investigação

Legar à posteridade em mármore uma cidade que recebeu constraída em tijolo foi uma das alegrias do Imperador Augusto ao fazer um balanço da sua vida, segundo Suetônio'. As propostas urbanísdcas do Princeps transformam-se em modelos para todas as novas cidades e capitais de colônia, incrementando-se deste modo o uso do mármore logo a pardr dos inícios do Império, perdurando ainda bem vivo nos finais do séc. IV, já numa sociedade em grande parte cristianizada. Séneca diz-nos, nos meados do séc. I d. C, que existia o ideal de que as paredes reluzissem com mármores importados da outra banda do mar, que se olhavam com admiração as crustae marmoriae que as revestiam e que era sinal do melhor estatuto caminhar sobre mármores. E Paciano de Barcelona, nos finais do séc. IV, encontra na renúncia ao marmoribus tegi, ao habitar em casas de mármore, uma forma de fazer penitência.

G-quadruplex ligands for cancer therapy

DNA may fold into a diversity of structures and topologies such as duplexes and triplexes. Some specific guanine-rich DNA sequences may even fold into a higher order structures denominated guanine G-quadruplexes (G4). These G-quadruplex forming sequences have shown biological interest since were found in telomeres and in promoter region of oncogenes. Thus, these G4 forming sequences have been explored as therapeutic targets for cancer therapy, since G4 formation was demonstrated to inhibit RNA-polymerase and telomerase activity. However, the G4 structures are transient and are only formed under specific conditions. Hence the main objective of this work is to develop new G4-specific ligands which may potentially find applications in the therapeutic area. Several potential G4-binding ligands were synthesized and characterized. The synthesis of these compounds consisted on a procedure based on van Leusen chemistry and a cross-coupling reaction through C-H activation, affording phenanthroline compounds (Phen-1, 50%; Phen-2, 20%), phenyl (Iso-1, 61%; Iso-2, 21%; Ter-1, 85%; Ter-2, 35%), and quinolyl (Quin-1, 85%; Quin-2, 45%) compounds. Screening assays for selecting the potential G4 compounds were performed by FRET-melting, G4-FID, CD-melting and DSF. Qualitative biophysical studies were performed by fluorescence and CD spectroscopy. Two high-specific G-quadruplex ligands, Phen-1 and Phen-2, were found to effectively bind telomeric and c-myc G4 structures. Phen-1 was found to stabilize parallel telomeric 22AG and c-myc sequence by 4.1 and 4.3 ˚C, respectively. Phen-2 also displayed high affinity towards 22AG (