Intracellular interferons in fish : a unique means to combat viral infection

Peer reviewedPublisher PD

Hafnium isotopic variations in volcanic rocks from the Caribbean Large Igneous Province and Galápagos hotspot tracks

[1] We report Hf isotope compositions of 79 lavas that record the early (∼5–95 Ma) history of the Galápagos plume volcanism. These include lavas from the Caribbean Large Igneous Province (CLIP; ∼95–70 Ma), the accreted Galápagos paleo-hot spot track terranes (54–65 Ma) of Costa Rica (Quepos, Osa and Burica igneous complexes), and the Galápagos hot spot tracks (<20 Ma) located on the Pacific seafloor (Cocos, Carnegie, Malpelo, and Coiba Ridges and associated seamounts). These samples have previously been well characterized in terms of major and trace elements, Sr-Nd-Pb isotopes and Ar/Ar ages. As a result of the relative immobility of the high field strength and rare earth elements during syn- and post-emplacement hydrothermal activity and low-temperature alteration, combined Lu-Hf and Sm-Nd isotope systematics, when used in conjunction with Pb isotopes, provide a particular powerful tool, for evaluating the source compositions of ancient and submarine lavas. The combined Nd-Hf isotope data suggest that three of the isotopically distinct source components found today in the Galápagos Islands (the Floreana-like southern component, the Fernandina-like central component, and the depleted Genovesa-like eastern component) were present in the CLIP already by 95–70 Ma. The fourth Pinta-like northern component is first recorded at about 83–85 Ma by volcanism taking place during the transition from the plume head/CLIP to plume tail stage and has then been present in the hot spot track continuously thereafter. The identification of the unique northern and southern Galápagos Plume Hf-Nd-Pb isotope source signatures within the CLIP and the oldest hot spot track lavas provides direct evidence that the CLIP represents the plume head stage of the Galápagos hot spot. Hafnium isotopes are consistent with the possibility that two types of sediment components may have contributed to the Hf, Nd and Pb isotope compositions of the Galápagos plume lavas. One component, characterized by Δ207Pb/204Pb ≈ 0 and high positive ΔεHf has an isotope signature indicative of relatively recently recycled pelagic sediment, a signature typical of the southern Galápagos island Floreana. The other component has an EM like isotopic composition resembling modern seafloor sediments with positive Δ207Pb/204Pb and lower ΔεHf, a signature typical of the northern Galápagos island Pinta

Regeneration capacity of Asparagus setaceus (Kunth) Jessop ‘Pyramidalis’ in in vitro cultures

Plant regeneration through the tissue culture techniques would be a excellent alternative for improving the quality and faster production of Asparagus species. The number of reports on application of biotechnological methods (such as direct organogenesis, indirect organogenesis and somatic embriogenesis) for ornamental asparagus are scarce in comparison to edible asparagus. The aim of this study was to verify the effectiveness of chemical and physical factors on organogenetic response of Asparagus setaceus ‘Pyramidalis’ explants. The results showed that nodes cultured on MS medium supplemented on IAA (1.71 µM) and BA (13.32 µM) gave highest number of shoots per explant (14 – in the fourth passage). Rhizogenesis were achieved on MS medium with IBA (2.45 µM) and ancymidol (2.88 µM). Finally, 90% of rooted shoots (microcuttings) survived. The fastest increase in callus tissue on internodal explants were observed on MS medium with addition of TDZ (9.08 µM) and adenine sulphate (10.86 µM)