Aspects of cell production in mantle tissue of Ciona intestinalis L. (Tunicata, Ascidiacea)

Renewal of cell population is needed in the tunic of ascidians, as the tunic cells are involved in many biological functions. Tunic cells are thought to arrive by migrating across the mantle epithelium into the tunic from the blood lacunae or the mesenchymal space. Electron microscope observations show that the mantle epithelium of Ciona intestinalis shares some proliferative characteristics, releasing cells into the tunic and thus providing an increase renewal of tunical cells in restricted zones of adult animals.     

Influence of the coordination geometry on the physicochemical properties of a copper(II) complex with a tailor-made calixarene-based ligand bearing dipyridyl pendants. An ESR, UV-Vis and CV study

Dipyridyl pendants, suitably attached onto a calix[4]arene fixed in its 1,3-alternate conformation, form stable complexes with copper(ii) in acetonitrile. Both the mononuclear and the homobinuclear species ([Cu(1)](2+) and [Cu(2)(1)](4+)), previously detected through a UV-Vis investigation, have been studied by ESR, UV-Vis and cyclic voltammetry. ESR and UV-Vis data clearly indicate that in the [Cu(1)](2+) species the nitrogen atoms of dipyridyl pendants are tetrahedrally arranged around copper(II). Computer models, optimised through molecular mechanics methods, further support these spectroscopic findings. The tetrahedral arrangement, achieved thanks to the anchoring of the dipyridyl moieties onto the calixarene platform, accounts for the easy reversible reduction of this species. The aspects associated with the reduction-oxidation of the homobinuclear species are also discussed.     

Biological activity of bicyclic and tricyclic diterpenoids from Salvia species of immediate pharmacological and pharmaceutical interest

Diterpenoids are a class of compounds that derive from the condensation of four isoprene units that leads to a wide variety of complex chemical structures, including acyclic bi-, tri-and tetra-cyclic compounds; in Salvia species, only bi-, tri-and tetra-cyclic compounds have been found. This review covers a wide range of biological activities and mode of action of diterpenoids isolated from Salvia species that might raise some pharmacological and pharmaceutical interest. We have produced a synoptic table where the biological activities of the main active principles are summarized. Our analysis emphasizes that diterpenoids from Salvia species continue to be a plant defence system since their antimicrobic activity. Experimental studies show that most of diterpenoids considered have cytotoxic and/or antiproliferative activity. Some of them have also cardiovascular and central effects. In a less extended manner, diterpenoids from Salvia species show gastrointestinal, urinary, antinflammatory, antidiabetic, ipolipidemic and antiaggregating effects. In the last decade, several clinical trials have been developed in order to investigate the real value of Salvia extracts treatment; results obtained are promising and confer scientific basis in the use of medicinal plants from folk medicine.     

Copper complex species within a fragment of the N-terminal repeat region in opossum PrP protein

A spectroscopic (UV-Vis, CD and EPR), thermodynamic and voltammetric study of the copper(ii) complexes with the Ac-PHPGGSNWGQ-NH(2) polypeptide (L), a fragment of the opossum PrP protein N-terminal four-repeat region, was carried out in aqueous solution. It suggests the formation of a highly distorted [Cu(L)H(-2)] complex species in the neutral region, the stereochemistry of which is ascribable to a square base pyramid and a CuN(3)O(2) chromophore, resulting from the coordination of a histidine imidazole and two peptide nitrogen atoms and probably oxygen atoms from water molecules. At basic pH values a [Cu(L)H(-3)](-) species with a pseudo-octahedral geometry was also obtained, with four nitrogen donor atoms in its equatorial plane, coming from the histidine residue and from peptidic nitrogen atoms. Interestingly, at pH values relatively higher than the neutrality, the coordination sphere of the copper complex in the [Cu(L)H(-2)] species changes its stereochemistry towards a pseudo-octahedron, as suggested by the change in the parallel copper hyperfine coupling constant of the EPR spectra at low temperature. A slight difference in the redox potentials between this two-faced [Cu(L)H(-2)] complex species seems to confirm this behaviour. Both potentiometric and spectroscopic data were compared with the analogous species obtained with the Ac-PHGGGWGQ-NH(2) peptide, belonging to the octarepeat domain of the human prion protein (hPrP) N-terminal region. The [Cu(L)H(-2)] species formed by the Ac-PHPGGSNWGQ-NH(2) decapeptide, having a slightly lower stability, turned out to be less abundant and to exist within a narrow pH range.     

Geochemical characterisation of Antarctic soils and lacustrine sediments from Terra Nova Bay

In Terra Nova Bay region (northern Victoria Land, Antarctica), the interactions among soil, meltwater and lakes are poorly understood with regard to the physicochemical transformations that occur when solid materials are exchanged among them. In order to ascertain the natural dynamics of several elements, namely Al, As, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Ti and Zn, as well as the perturbations by human activities and/or global contamination, soils and sediments from four catchments (Tarn Flat, Edmonson Point, Inexpressible Island and Northern Foothills) were studied.To accomplish the above mentioned objectives, the particle-size distribution and mineralogical composition, as well as the total C, H and N contents and the total concentrations of the investigated elements were determined. Finally in order to assess metal mobility, the modified BCR three-step sequential extraction procedure was applied to the samples and the partitioning of five metals, namely Cr, Fe, Mn, Pb and Zn, into different fractions was determined.Lithology and topography are the main factors that differentiate the physicochemical characteristics of the soils and sediments investigated. The lacustrine sediments and the soils sampled around the lakes showed a similar mineralogical and chemical composition, as evidence that rock- and soil-weathering processes occur primarily during the warm summer periods, when the lakes are partially ice-free. Nevertheless the presence of chlorite in these systems indicated that chemical weathering has taken place even in these extreme conditions. In general, the geochemical composition of soils and sediments in this Antarctic area seems to be influenced mainly by the nature of the bedrock and by the input of sea-spray, and, to a lesser degree, by mechanical and chemical weathering as well as by biological processes; no evidence of a local or global anthropogenic contamination was found.     

Trace metal concentration in wild avian species from Campania,Italy

This study was conducted to determine heavy metals concentrations in tissues of 94 birds belonging to different species from coastal areas of Naples and Salerno (Southern Italy) in order to provide baseline data concerning trace element levels in wild birds living in or close to an area characterized by high anthropogenic impact. Additional aim of this study was to verify if diet influenced metal accumulation, so birds were classified as birds of prey, fish eating birds and insectivorous birds.     

Hydride Migration from a Triangular Face to a Tetrahedral Cavity in Tetranuclear Iron Carbonyl Clusters upon Coordination of [AuPPh3]+ Fragments

Metal hydrides are of fundamental importance in chemistry, both as solid‐state materials and molecular compounds. The first low‐valent molecular metal cluster containing an interstitial four‐coordinate hydride in a tetrahedral site is decribed, which undergoes hydride migration from the surface to the tetrahedral cavity of the cluster upon coordination of a [AuPPh₃]⁺ fragment. The [HFe₄(CO)₁₂(AuPPh₃)₂]^? mono‐anion, which contains a surface μ₃‐H, was obtained from the reaction of [HFe₄(CO)₁₂]^3? with two equivalents of [Au(PPh₃)Cl]. This is, in turn, transformed into the neutral [HFe₄(CO)₁₂(AuPPh₃)₃] upon addition of a third [AuPPh₃]⁺ fragment, with concomitant migration of the unique hydride from the surface of the cluster to its tetrahedral cavity. All of these species have been fully characterized in solution by means of IR and multinuclear NMR spectroscopy, and in the solid state by single‐crystal X‐ray diffractometry.