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- SourceAvailable from: Norberto Farfán[Show abstract] [Hide abstract]
ABSTRACT: The crystal structure of the title compound, CHBrO·CHCl, prepared in six steps from diosgenin, confirmed that the configurations of the stereogenic centers, positions 20 and 25, remain unchanged during the reaction. The six-membered , and rings have chair conformations. The five-membered ring has an envelope conformation (with the methyl-substituted C atom fused to ring as the flap) and the six-membered dihydro-pyran ring adopts a twist-boat conformation. In the crystal, mol-ecules are linked C-H⋯O and C-H⋯Cl hydrogen bonds, the latter involving the dichloro-methane solvent mol-ecule, forming a three-dimensional supra-molecular network.
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ABSTRACT: The relationship between accumulation of Pb2+ and changes in GSH biosynthesis was analyzed in both leaves and roots of the Pb2+-hyperaccumulator aquatic fern Salvinia minima, after exposure to 40 μM Pb(NO3)2. Lead accumulation in both tissues increased the accumulation of GSH, increased the enzymatic activity of glutathione synthase (GS), and caused changes in the expression levels of SmGS genes in both tissues. The damage caused by Pb on plant performance, was evaluated by the changes in the content of pigments, particularly on the carotenoids content. Lead accumulation caused more damage in roots than in leaves as indicated by the decrease on their carotenoids content. It is interesting that in leaves, the concentration of GSH, the activity of GS and the expression levels of SmGS gene were all higher than in roots. These results, together with our previous finding that roots accumulated more phytochelatins than did leaves of S. minima plants exposed to similar concentrations of lead (Estrella et al., 2009), suggest that the Pb-hyperaccumulator aquatic fern, S. minima, displays a coordinated and differential response to Pb2+ at leaves and roots, where GSH may play an important role in protecting leaves from the detrimental effects of lead, perhaps by counteracting the effect of free radicals.
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ABSTRACT: Thirty six (36) native fungal strains from the state of Yucatan were first screened for ligninolytic activity on solid media containing ABTS. Molecular identification based on ITS rDNA region and PCR fingerprinting of seven selected fungi isolates were carried out. Molecular characterization based on genetic fingerprinting was helpful in determining unequivocally the differences between isolates at genera and species levels. The seven isolates showed ABTS oxidation zones in plates but only five strains produced extracellular laccase. The strains identified as Trametes hirsuta (GenBank accession numbers GQ280372 and GQ280373) showed the highest laccase production. The strain Bm-2 displayed the greatest laccase activity and dye decolourization ability in 72 h without the addition of mediators. Both the high laccase activity shown by Bm-2 and its ability to decolorize dyes are a good indication of its possible use in the treatment of textile effluents.
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