Papers by Stefania Ancora
The two-photon 1s 2 2s2p 3 P0 → 1s 2 2s 2 1 S0 transition in berylliumlike ions is theoretically ... more The two-photon 1s 2 2s2p 3 P0 → 1s 2 2s 2 1 S0 transition in berylliumlike ions is theoretically investigated within a full relativistic framework and a second-order perturbation theory. We focus our analysis on how electron correlation, as well as the negative-energy spectrum can affect the forbidden E1M 1 decay rate. For this purpose we include the electronic correlation by an effective potential and within an active-electron model. Due to its experimental interest, evaluation of decay rates are performed for berylliumlike xenon and uranium. We find that the negative-energy contribution can be neglected in the present decay rate. On the other hand, if contributions of electronic correlation are not carefully taken into account, it may change the lifetime of the metastable state by 20%. By performing a full-relativistic jj-coupling calculation, we found discrepancies for the decay rate of an order of 2 compared to non-relativistic LS-coupling calculations, for the selected heavy ions.
Marine Environmental Research, 2006
The main aim of this study was to develop and validate a suite of sensitive responses (biomarkers... more The main aim of this study was to develop and validate a suite of sensitive responses (biomarkers) for monitoring conservation status and ecotoxicological impact in Posidonia oceanica meadows. Analytical methods were developed for NADPH cytochrome c reductase, ethoxycoumarin-o-deethylase (ECOD), guaiacol peroxidase (GPOX) and superoxide dismutase (SOD) assays. A preliminary proteomic approach using 2-D electrophoresis was also proposed as a biomarker. These techniques were initially tested on samples of posidonia exposed experimentally to various contaminants. Once validated, this approach was applied to posidonia in a field study. Samples of the seagrass were collected at four sites with potentially different environmental impact along the northern Tyrrhenian coast. The results showed that reductase activity was significantly induced in the various sampling areas with respect to the reference site. GPOX and SOD showed a similar trend; the highest activities were found in samples collected off a chlor-alkali plant and near a river estuary. Analysis of trace elements, polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds (OCs) in posidonia leaves showed differences between sites. A significant correlation was found between Hg concentrations and GPOX activity and between Cr, Al and As concentrations and reductase activity. The results validated these biomarkers in posidonia for the assessment of ecotoxicological impact on the coastal ecosystem.
Environmental Toxicology and Chemistry, 2004
Levels of Hg, Cd, Pb, Cu, Zn, Fe, and Mn were assessed by using Posidonia oceanica as a bioindica... more Levels of Hg, Cd, Pb, Cu, Zn, Fe, and Mn were assessed by using Posidonia oceanica as a bioindicator in the Gulf of Naples (southern Italy). Lepidochronology, which enables retroactive dating of scales and rhizomes of this seagrass, was combined with atomic spectrometry to assess temporal trends of trace elements in dated scales and rhizomes over a 10-year period. Lepidochronology occasionally has been used to monitor Hg in dated scales, but never has been used to determine concentrations of other trace elements in dated rhizomes. Data were compared between various structural parts of seagrass and between sampling sites. Concentrations of some elements found in dated scales or rhizomes showed a similar trend in most of the sites; increasing for Hg and Cu and decreasing for Pb, Fe, and Zn. Contaminant levels indicated by seagrass meadows varied from metal to metal. Concentrations of Hg, Cd, and Pb fell within the ranges measured in other areas considered to have low levels of heavy metal pollution, whereas Cu, Mn, and Zn had higher concentrations only in some years. However, on the basis of other studies, none of the sampling sites are considered to have high contamination levels.
Science of The Total Environment
The work was addressed to study the sensitivity of the enzyme carbonic anhydrase (CA) to chemical... more The work was addressed to study the sensitivity of the enzyme carbonic anhydrase (CA) to chemical pollution in the hepatopancreas of the bioindicator organism Mytilus galloprovincialis in the context of a multimarker approach in view of ecotoxicological biomonitoring and assessment application. The study was carried out by means of a transplanting experiment in the field, using caged organisms from an initial population exposed in the field in two areas of interest: Augusta-Melilli-Priolo, an heavy polluted industrial site (eastern Sicily, Italy), and Brucoli (eastern Sicily, Italy) an area not affected by any contamination and selected as a reference site. Mussels in Augusta presented a significant increase in the digestive gland CA activity and gene expression compared to the animals caged in the control site of Brucoli. The CA response in animals from the polluted site was paralleled by proliferation/increase in the size of lysosomes, as assessed by Lysosensor green charged cells, induction of metallothionein, up-regulation of hif-α (hypoxia-inducible factor), metabolic changes associated with protein metabolism, and changes in the condition factor. Biological responses data were integrated with information about sediment chemical analysis and metal residue concentration in animal soft tissues. In conclusion, obtained results highlighted the induction of CAs in the hepatopancreas of Mytilus galloprovincialis following to pollution exposure, and demonstrated its suitability to be integrated into a multimarker approach for the detection and characterization of the stress status induced by pollution exposure in this bioindicator organism.
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Papers by Stefania Ancora