Publications (2)2.96 Total impact
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ABSTRACT: The mechanism of action of praziquantel (PZQ), the drug of choice against schistosomiasis, is still unclear. Since exposure of schistosomes to the drug is associated with calcium influx and muscular contraction, calcium channels have been suggested as the target, although direct combination of PZQ with their subunits was never demonstrated. We report a hitherto unknown effect of PZQ, namely the inhibition of nucleoside uptake, as observed in living worms using radio-isotope labelled adenosine and uridine. This effect is clearly seen in schistosomes but is absent in mammalian cells in culture. Moreover it is a specific pharmacological effect seen exclusively with the active levo-R(-)stereo isomer of the drug, and is shared by at least one benzodiazepine having antischistosomal activity. This novel effect acquires significance given that schistosomes cannot synthesize purine nucleosides de novo. A possible relationship between this novel effect and the known action of PZQ on calcium channels is discussed, since adenosine is known to bind to specific receptors and to behave as an indirect antagonist of calcium release in mammalian cells. If calcium channels were correlated with adenosine receptors also in schistosomes, as they are in mammals, this would support the hypothesis that PZQ-induced calcium influx may be correlated to adenosine receptor blockade.Parasitology 08/2007; 134(Pt 9):1215-21. · 2.96 Impact Factor
Article: Interactions between bluefish Pomatomus saltatrix (L.) and coastal sea-cage farms in the Mediterranean Sea[show abstract] [hide abstract]
ABSTRACT: Coastal sea-cage farms aggregate large concentrations of pelagic and demersal fish. The large numbers of cultured fish and aggregated wild fish often attract a range of marine mammal predators which may break into cages and attack the cultured fish. To date, predation by a finfish species within sea-cages has not been documented. In the Mediterranean Sea, the bluefish Pomatomus saltatrix (L.) aggregates around sea-cage farms and enters into cages to predate on the cultured fish. We obtained information about the effects of bluefish predation on aquaculture production through a questionnaire that was completed by fish farmers in Spain, Italy, Malta, Turkey, Greece and Cyprus. In addition, we identified the abundance, size and stomach contents of bluefish aggregated around three fish farms on the coast of Spain through visual counts, and from captured bluefish both inside and outside of the sea-cages. Bluefish occurred around fish farms in Spain, Italy, Malta and Turkey. Farmers in SE Spain reported its presence only inside seabream (Sparus aurata) cages, while in Turkey bluefish were reported from inside seabass (Dicentrarchus labrax) and seabream cages. Greatest aggregated biomass of bluefish reached 1049 and 3191 kg at the Altea and Guardamar farms, respectively, with abundance peaking at 4500 individuals at both farms. Size structures differed markedly between farms, with smaller individuals aggregating at Altea. Stomach content analysis revealed that bluefish on the outside of sea-cages consumed pelagic species such as Sardinella aurita and Trachurus mediterraneus, while they predated on seabream once they incurred into cages, often consuming only the tails of many fish. The interaction of bluefish with sea-cage aquaculture is, at present, a problem of local concern restricted to some areas of the Mediterranean Sea, but its widespread distribution suggests this piscivore may be a problematic predator in other regions.Aquaculture.