267 research outputs found
History, ecology and trends for artificial reefs of the Ligurian Sea, Italy
No full textFrom 1970 to the present 10 artificial reef sites have been developed in coastal waters of the Ligurian Sea, Italy. They range from Ventimiglia, in the west, to La Spezia, in the east, with the
largest and best known reef complex being located in the Gulf of Genoa at Loano and consisting of 2,745 m3, about 5,200 t of material and covering a surface of 350 ha. Design and construction practices have advanced from an initial, unsuccessful
effort that used automobile bodies (now banned) to current use of custom-designed concrete modules deployed systematically. Funding for reef construction has come since 1983. The earliest aim of reefs was as a physical barrier to protect habitats against illegal otter trawl fishing. Newer objectives include habitat restoration, enhancement of biodiversity and fishing catch, and
research to test materials and designs for physical and ecological performance. Reefs also functions as environmental observation stations, with the invasive species Caulerpa taxifolia (Vahl)
C. Agardh, being recorded on the reef at Alassio
Molecular order in self-assembled multilayers of stearic acid
No full textSelf-assembled multilayers of stearic acid were obtained by evaporating a drop of stearic acid dissolved in organic solvent onto a cleaned glass slide. X-ray diffraction and scanning force microscopy (SFM) were used to determine the bulk structure and to study the surface at molecular level. In samples prepared from decane solution, at least two crystalline forms (A + C and B + C, but seldom A + B + C) coexist and the molecules at the surface appear arranged according to a two-dimensional non-centered rectangular lattice. After annealing of the samples at 80 degrees C (slightly above the melting point of stearic acid), the C-form exists singly: accordingly, the molecular arrangement at the surface reverts to an hexagonal pattern. A periodic buckling superstructure is also observed by SFM in non-annealed samples. Moreover, X-ray diffraction results indicate that recrystallization processes occur
How human forcings affect ecological properties of large pelagic fish in the Mediterranean? Historical genetic changes in the overexploited bluefin tuna (Thunnus thynnus).
No full textBased on a comparative analysis of genetic diversity at 7 microsatellite loci in ancient (archived skeletal specimens) and modern (freshly
collected individuals) samples of Thunnus thynnus collected in the Mediterranean Sea, we assessed temporal changes and spatial variation
of genetic and demographic (genetically-related) features in the overexploited Mediterranean stock of bluefin tuna. From the analysis of
more than 300 individuals, a temporal stability of genetic diversity over about 90 years but significant changes in the genetic structure of
the stock were achieved. Such results argue for an evidence that, in the Mediterranean, stock overexploitation has not yet corrupted the
genetic potential of such living resource and that bluefin tunas are not fully panmictic
Trehalose interacts with phospholipid polar heads in Langmuir monolayers
No full textSurface pressure-area isotherms, surface potential-area isotherms and fluorescence microscopy were employed to study the behavior of phospholipid monolayers at the air/water interface when trehalose was added to the aqueous subphase. In the presence of this sugar, the critical area corresponding to the onset of surface potential increases, indicating that trehalose is participating in the network of hydrogen bonds between the phospholipid polar heads. In addition, it causes an expansion of the isotherm, hindering the formation of the liquid-condensed phase. The collapse area is significantly increased, indicating that trehalose takes part in the monolayer structure without being expelled even at high surface pressures. A quantitative comparison of the collapse areas and critical areas for surface potential in the presence and in the absence of the sugar shows that an almost fixed number of trehalose molecules interacts with the monolayer independently of the surface packing, thus indicating that the observed effects can be ascribed to a tight binding of trehalose to the polar heads in a defined ratio. No similar effects were observed in the presence of glucose. We rationalize the reported data in light of the water replacement hypothesis, developed to explain the preservation of biomembranes by trehalose; this hypothesis suggests that trehalose forms hydrogen bonds with the membrane polar headgroups, thus replacing the water of hydration at the membrane-fluid interface and maintaining the headgroups at their hydrated position
Influence of subphase viscosity on Langmuir monolayer flow
No full textThe flow of a Langmuir monolayer driven through a floating channel by a surface pressure gradient is measured as a function of the channel width at different surface pressures. The comparison of the experimental data with the mathematical models shows that at low surface pressure the now is governed by the subphase viscosity, while at higher surface pressure the now is governed by both surface viscosity and bulk viscosity
Optical characterization of polymethylmetacrylate-poly(3-alkylthiophene) Langmuir Blodgett films.
No full textWe have synthesized a highly regioregular poly(3-alkylthiophene) containing an oxygen atom in the side chain, poly(3-pentylmethoxythiophene) (P5OMe). We have studied the formation of Langmuir-Blodgett (LB) multilayer structures prepared by mixing P5OMe with highly isotactic polymethylmethacrylate (PMMA), and we have characterized the structure obtained by means of UV-Visible absorption, photoluminescence measurements and AFM. A certain degree of orientation of the macromolecules in the dipping direction was observed
Molecular order in solvent-cast stearic acid films
No full textAtomic force microscopy was used to study the structures obtained by evaporating a drop of stearic acid dissolved in an organic solvent on a glass substrate. Bulk aggregates composed of molecular layers and flat dendritic shapes were found. According to the solvent used, two different crystalline lattices were observed and lattice symmetries together with unit mesh constants were determined. A periodic buckling superstructure of the crystalline lattice was observed for two of the solvents used
Nucleophosmin contains amyloidogenic regions that are able to form toxic aggregates under physiological conditions
No full textNucleophosmin (NPM)-1 is a multifunctional protein involved in a variety of biologic processes and has been implicated in the pathogenesis of several human malignancies. To gain insight into the role of isolated fragments in NPM1 activities, we dissected the C-terminal domain (CTD) into its helical fragments. In this study, we observed the unexpected structural behavior of the peptide fragment corresponding tohelix(H) 2 (residues 264-277). This peptide has a strong tendency to form amyloidlike assemblies endowed with fibrillar morphology and b-sheet structure, under physiologic conditions, as shown by circular dichroism, thioflavin T, and Congo red binding assays; dynamic light scattering; and atomic force microscopy. The aggregates are also toxic to neuroblastoma cells, as determined using 3-(4;5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction and Ca2+ influx assays. We also found that the extension of the H2 sequence beyond its N terminus, comprising the connecting loop with H1, delayed aggregation and its associated cytotoxicity, suggesting that contiguous regions of H2 have a protective role in preventing aggregation. Our findings and those in the literature suggest that the helical structures present in the CTD are important in preventing harmful aggregation. These findings could elucidate the pathogenesis of acute myeloid leukemia (AML) caused by NPM1 mutants. Because the CTD is not properly folded in these mutants, we hypothesize that the aggregation propensity of this NPM1 region is involved in the pathogenesisofAML.Preliminary assays on NPM1-Cter-MutA, the most frequent AML-CTD mutation, revealed its significant propensity for aggregation. Thus, the aggregation phenomenashould be seriously considered in studies aimed at unveiling the molecular mechanisms of this pathology. - Di Natale, C., Scognamiglio, P. L., Cascella, R., Cecchi, C., Russo, A., Leone, M., Penco, A., Relini, A., Federici, L., Di Matteo, A., Chiti, F., Vitagliano, L., Marasco, D. Nucleophosmin contains amyloidogenic regions that are able to form toxic aggregates under physiological conditions
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