Simultaneous and Different Binding Mechanisms of 4′,6-Diamidino-2-phenylindole to DNA Hexamer (d(CGATCG))2 A 1H NMR STUDY

The solution structure of the complex between 4′,6-diamidino-2-phenylindole (DAPI) and DNA oligomer (d(CGATCG))2 at a 2:1 drug/duplex ratio has been characterized by combined use of proton one- and two-dimensional NMR spectroscopy, molecular mechanics, and molecular dynamics computations. Intermolecular nuclear Overhauser effects (NOEs), DNA structure perturbations, and resonance shifts induced by binding provide evidence that DAPI interacts with DNA hexamer by two different binding mechanisms, in fast exchange on the NMR time scale, without any significant distortion of the B-type conformation of DNA hexamer. The results indicate that the ligand binds into the minor groove of the central 5′-ATC-3′ region of the hexamer and on the outside of the oligomer by a π,π-stacking interaction with the terminal C1:G6 base pairs. A model for both binding mechanisms that accounts for all experimental data was generated by molecular mechanics and dynamics calculations based on experimental NOEs. In the minor groove binding, N2 amino group of G2 precludes a deep insertion of phenyl ring of DAPI into the groove. Position and orientation of the drug in the external stacking interaction resemble those suggested for intercalation of DAPI between C:G base pairs

Algae as a Potential Source of Food and Energy in Developing Countries

Algal biomass has large potential for the production of fuels and of value added chemical products. A brief survey of methods for the recovery of the biomass, for its successive transformation, and of the potential targets is here provide

Metastable states in plateaus and multi-wave epidemic dynamics of Covid-19 spreading in Italy

The control of Covid 19 epidemics by public health policy in Italy during the first and the second epidemic waves has been driven by using reproductive number Rt(t) to identify the supercritical (percolative), the subcritical (arrested), separated by the critical regime. Here we show that to quantify the Covid-19 spreading rate with containment measures (CSRwCM) there is a need of a 3D expanded parameter space phase diagram built by the combination of Rt(t) and doubling time Td(t). In this space we identify the dynamics of the Covid-19 dynamics Italy and its administrative Regions. The supercritical regime is mathematically characterized by i) the power law of Td vs. [Rt(t)-1] and ii) the exponential behaviour of Td vs. time, either in the first and in the second wave. The novel 3D phase diagram shows clearly metastable states appearing before and after the second wave critical regime. for loosening quarantine and tracing of actives cases. The metastable states are precursors of the abrupt onset of a next nascent wave supercritical regime. This dynamic description allows epidemics predictions needed by policymakers to activate non-pharmaceutical interventions (NPIs), a key issue for avoiding economical losses, reduce fatalities and avoid new virus variant during vaccination campaignComment: 14 pages, 5 figure

Antioxidant properties of resveratrol and piceid on lipid peroxidation in micelles and monolamellar liposomes.

The antioxidant activities of trans-resveratrol (trans-3,5,4′-trihydroxystilbene) and trans-piceid (trans-5,4′- dihydroxystilbene-3-O-β-D-glucopyranoside), its more widespread glycosilate derivative, have been compared measuring their inhibitory action on peroxidation of linoleic acid (LA) and the radical scavenging ability towards different free radicals (such as DPPH) and radical initiators. It has been found that the two stilbenes have similar antioxidant capacity, while the comparison with BHT (2,6-di-tert-butyl-4-methylphenol) and α-tocopherol (vitamin E, vit. E), taken as reference, points out a slower but prolonged protective action against lipid peroxidation. Furthermore, piceid appears more efficacious than resveratrol as a consequence of the reaction of the latter with its radical form. The DSC profiles of phosphatidylcholine liposomes of various chain lengths, and EPR measurements of spin labelled liposomes demonstrated that the susceptible hydroxyl group of these compounds are located in the\ud lipid region of the bilayer close to the double bonds of polyunsatured fatty acids, making these stilbenes particularly suitable for the prevention and control of the lipid peroxidation of the membranes

The extreme environment of a library: Xerophilic fungi inhabiting indoor niches

The use of Compactus shelves by libraries and archives is a good solution to optimize the storage space and prevent dust deposits on books. However, they are probably the cause of severe cases of fungal colonization in historical library materials. A typical phenomenon occurs as a spread of white mycelial growth forming scattered spots, mainly on volumes with leather or fabric bindings. Recent studies have identified the xerophilic fungus Eurotium halophilicum (anamorph Aspergillus halophilicus) as responsible for this kind of contamination. A similar situation was found inside the Library of Humanities (BAUM), at Ca' Foscari University, Venice (Italy). Various sampling methods, including cotton swabs and adhesive tape, were adopted to isolate fungi from books and a set of aerobiological analyses was performed to characterize the environment of the repository. The presence of E. halophilicum on both books and in the indoor air was confirmed by direct observation of adhesive tape samples, microscopic observations and molecular methods. Moreover, Aspergillus creber and Aspergillus protuberus belonging to the revised group Aspergillus section Versicolores, were also isolated for the first time in Italian conservation environments

Detection of volatile metabolites of moulds isolated from a contaminated library

The principal fungal species isolated from a contaminated library environment were tested for their microbial volatile organic compound (MVOC) production ability. Aspergillus creber, A. penicillioides, Cladosporium cladosporioides, Eurotium chevalieri, E. halophilicum, Penicillium brevicompactum and P. chrysogenum were cultivated on suitable culture media inside sample bottles specifically designed and created for direct MVOC injection to a GC-MS instrument. The fungal emissions were monitored over several weeks to detect changes with the aging of the colonies, monitored also by respirometric tests. A total of 55 different MVOCs were detected and isopropyl alcohol, 3-methyl-1-butanol and 2-butanone were the principal compounds in common between the selected fungal species. Moreover, 2,4-dimethylheptane, 1,4-pentadiene, styrene, ethanol, 2-methyl-1-butanol, acetone, furan and 2-methylfuran were the most detected compounds. For the first time, the MVOC production for particular fungal species was detected. The species A. creber, which belongs to the recently revised group Aspergillus section Versicolores, was characterized by the production of ethanol, furan and 1,4-pentadiene. For the xerophilic fungus E. halophilicum, specific production of acetone, 2-butanone and 1,4-pentadiene was detected, supported also by respirometric data. The results demonstrated the potential use of this method for the detection of fungal contamination phenomena inside Cultural Heritage's preservation environments. (C) 2016 Elsevier B.V. All rights reserved