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Valuing alternative bundles of landscape attributes: cost-benefit analysis for...
Santos, João LimaThe role of landscape valuation and extended cost-benefit analysis inlandscape conservation decision-making is first addressed. It is stressed that substantial research on how to value alternative conservation schemes is required, in order to cope with emerging policy needs. An analytical frame for the valuation of alternative landscape conservation schemes is then discussed. This frame enablesthe analyst to se...
The role of target membrane sialic acid residues in the fusion activity of the ...
Ramalho-Santos, João; Lima, João Pedroso DeThe influenza virus enters target cells via the action of hemagglutinin proteins (HA) inserted into the viral envelope. HA promotes membrane fusion between the viral envelope and endosomal membrane at low pH, following viral binding to sialic acid-containing receptors on target cells, and internalization by endocytosis. The effect of target membrane sialic acid residues on the fusion activity of the influenza v...
Fluorescent probes for monitoring virus fusion kinetics: comparative evaluation...
Nunes-Correia, Isabel; Eulálio, Ana; Nir, Shlomo; Düzgünes, Nejat; Ramalho-Santos, João; Lima, Maria C. Pedroso deFluorescence assays for viral membrane fusion employ lipidic probes whose kinetics of fluorescence dequenching should mimic the actual kinetics of membrane merging. We examined the fusion of influenza virus with CEM cells, erythrocyte ghosts or liposomes by monitoring the fluorescence dequenching of each one of the three probes, octadecylrhodamine B chloride (R18), N-(lissamine rhodamine B sulfonyl)phosphatidyl...
Fusion and Infection of Influenza and Sendai Viruses as Modulated by Dextran Su...
Ramalho-Santos, João; Lima, Maria Pedroso deWe have directly compared the effect of two types of dextran sulfate with distinct molecular weights (500 kDa and 5 kDa) on the fusion activity and infectivity of both Sendai and influenza viruses, two lipid-enveloped viruses that differ in their routes of entry into target cells. To correlate membrane merging and infectivity MDCK cells were used as targets for the viruses in both approaches. In either case pro...
Role of a Transbilayer pH Gradient in the Membrane Fusion Activity of the Influ...
Ramalho-Santos, João; Lima, Maria C. Pedroso deIt had been suggested that influenza virus-mediated membrane fusion might be dependent on a pH gradient across a target membrane. We have designed experiments in which this issue could be addressed. Two populations of liposomes were prepared, both simulating the plasma membrane of target cells, but with the pH of the internal aqueous medium buffered either at pH 7.4 (physiological cytosol pH) or at pH 5.0 (endo...
Partial fusion activity of influenza virus toward liposomes and erythrocyte gho...
Ramalho-Santos, João; Lima, Maria C. Pedroso de; Nir, ShlomoFinal extents of fusion of influenza virus (A/PR/8/34 strain) with neutral and partially acidic liposomes were monitored with (i) a fluorescence resonance energy-transfer assay in which the liposomes were labeled and (ii) by the dequenching of octadecylrhodamine, initially incorporated in the viral membrane. The latter assay was also employed in the fusion of influenza virus and Sendai virus with erythrocyte gh...
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