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ABSTRACT: In the last fifteen years the presence and distribution of large aggregates in the Mediterranean Sea have begun to be studied suggesting that these particles could play a relevant role in the carbon biogeochemistry of the basin. However the massive formation is a sporadic event and it is often difficult to detect. During the autumn of 2000 high densities of mucilage aggregates were observed in the major part of the coastal zone of the Tyrrhenian Sea (western Mediterranean Sea). The chemical composition and origin of these aggregates were evaluated. The carbohydrates, proteins, lipids and the humic and fulvic acid fractions constitute 45– 68% of the organic carbon (OC). Marine origin was suggested by UV spectra and C/N ratios of humic sub-stances extracted from mucilage samples. The polysaccharide component was isolated and purified by extraction of four fractions of different solubility and the saccharide carbon percentage ranged from 13 to 20% of the OC. By comparison the qualitative and quantitative monosaccharide, fatty acid and sterol compo-sitions were very similar to those obtained from Adriatic pelagic mucilages, while on the other hand the re-sults showed remarkable differences in comparison to benthic aggregates. Scanning electron microscopy (SEM) on native samples showed a complex morphology with the presence of fibrillar structures forming a highly branched tri-dimensional network similar to those found in Adriatic pelagic samples.
Marine Chemistry 02/2012; 132-133:83-94. · 3.07 Impact Factor
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ABSTRACT: Two synthetic genes that code for artificial proteins have been constructed that were modeled on the most regularly repeated hydrophobic domain of human tropoelastin. We compare the physicochemical properties of the recombinant products that differ in their primary structure; the alanine/lysine-rich cross-linking domains, which are highly conserved in mammalian tropoelastin, were either present or absent in the recombinant products. Both biopolymers showed thermoresponsive properties, and variations were observed that were dependent on solution conditions. Cell compatibility was assayed using the biopolymers as coating agents in culture experiments with a neuroblastoma cell line; cell adhesion and proliferation effects were evaluated. The cells were found to retain their neural differentiation potential. The data presented in our work support the usefulness of these versatile biopolymers for a variety of applications related to biotechnology and biomedicine.
Biomacromolecules 11/2010; 11(12):3256-65. · 5.48 Impact Factor
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ABSTRACT: The potential of producing patterned, bioactive coatings with Human Elastin-Like Polypeptides (HELPs) has been investigated. The physicochemical features of these compounds have evidenced some differences between the two recombinantly expressed products. By a device-free, simple route and avoiding the use of chemically unfriendly compounds, micropatterned surfaces with the ability to control cell behavior could be obtained. Thus, HELPs represent a very promising class of macromolecule for future applications in surface engineering.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2010; 2010:819-22.
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ABSTRACT: The chemical composition of mucilage aggregates found during summer 2000, 2001 and 2002 in the North Adriatic Sea depends on the nature of the organic matter during aggregation, on the environmental conditions of the site of formation and on the transformations during ageing. The mucilages were composed of organic matter, together with a significant inorganic fraction. Elemental analysis revealed 12.5-32.2% of organic carbon, 0-7.3% of inorganic carbon and 1.0-3.7% of nitrogen. The C(org)/N ratios of most aggregates were between 7.5 and 12.6, values close to those found in the suspended matter; higher ratios were found in large-size (>5 m) aggregates which are probably older. The content of carbohydrates and proteins determined in the aggregates, respectively, 15.4+/-8.9% and 7.9+/-4.8%, w/w, showed a prevalence of carbohydrates over proteins. Neutral carbohydrate analysis of purified polysaccharides from mucilage samples showed very similar signatures with high relative abundance of galactose and glucose. Humic, fulvic and humin substances extracted from the mucilages constitute an important fraction of the organic matter in the aggregates. The humin (a fraction insoluble in acidic and basic media) was present in all mucilage samples, indicating the refractory nature of a part of the organic matter in the mucilage. The iron and calcium could play a role during the aggregation process to form a complex with polysaccharides and humic fractions. The C(org)/N ratio 10+/-2 found in the humic acids extracted from the Adriatic aggregates disclosed a marine origin. The low phosphorus content and the high C(org)/P ratio found in the aggregates might depend from high bacteria activity or from the aggregation of organic fractions depleted of phosphorus. The principal inorganic species contained aluminium and silicon, part of which was of biogenic origin and was more significant in the offshore mucilage aggregates than in the coastal ones. The Si(biog)/C(org) ratio showed that diatoms were always present in the aggregates, although it cannot be established whether these are the producers or these develop within the aggregates.
Science of The Total Environment 01/2006; 353(1-3):232-46. · 3.29 Impact Factor
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ABSTRACT: Bacterial degradation of mucilaginous aggregates (creamy layers, stringers and macroflocs) collected during two summer events (2001-2002) was tested. The objective was to describe the temporal trend of the bacterial activity, abundance and composition in the aggregated and dissolved organic matter under different trophic conditions. In the native aggregates proteins and organic phosphorous were actively hydrolyzed as aminopeptidase and alkaline phosphatase activities represented up to 87% and 25% of total activity, respectively; polysaccharides were less hydrolyzed and the highest activities were observed for beta-glucosidase (5% of the total). This hydrolysation pattern tends to a progressive accumulation of long persistent polysaccharides. During short term incubations nutrient addition (P, N and Glucose) differently stimulated bacterial growth in the seawater: P played the main role in stimulating bacterial production from 3 to 6 folds higher than in the control, whereas a secondary C-limitation was observed only for bacteria growing on seawater from macroflocs. This scarce dissolved organic carbon (DOC) bioavailability was confirmed by the lower DOC removal (13% macroflocs, 36% stringers). The total amount of carbon incorporated by bacteria living on aggregates was similar (0.58 mg C L(-1)) both in the control and under P enrichments showing a more balanced condition with respect to the seawater. Hence the well-known P limitation in the Northern Adriatic Sea affects only dissolved organic carbon uptake without influencing the uptake of aggregated organic matter. Organic matter limitation was observed only on stringers--total C incorporated raised to 0.96 mg C L(-1) after PNG addition. Macroflocs release of refractory compounds leads to DOC accumulation (73 microM DOC) contributing to inflate the pool of refractory DOC in the surrounding waters. Several evidences, including different monosaccharide composition of stringers and macroflocs (glucose 15% and 56% on stringers and macroflocs, respectively), bring to the conclusion that stringers are in an older stage in comparison with macroflocs. Community composition described by fluorescence in situ hybridization did not show significant differences between free-living and attached bacteria but it was modified by the different enrichment conditions: Cytophaga-Flavobacteria increased after inorganic nutrients enrichments while organics advantaged gamma-Proteobacteria.
Science of The Total Environment 01/2006; 353(1-3):270-86. · 3.29 Impact Factor
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ABSTRACT: A laboratory study was performed on the extracellular production of carbohydrates by the marine diatoms Cylindrotheca closterium, Thalassiosira pseudonana and Skeletonema costatum. The investigation was aimed at elucidating the role of P-starvation and growth status on abundance and chemical characteristics of the released non-attached polysaccharides. Inorganic phosphorus depletion determined an increase of total polysaccharides in all species examined compared to nutrient-replete (complete f/2) conditions. The highest abundance of polysaccharides per unit cell was found in T. pseudonana (28.4 micromol C 10(-6) cells), followed by C. closterium (2.56 micromol C 10(-6) cells) and S. costatum (1.18 micromol C 10(-6) cells). Maximum production rates were found at the transition between exponential and stationary growth phase. Gas-chromatographic analysis of the dissolved fraction showed glucose to be the most abundant monomer in exponentially growing, P-replete cultures (81.6%, 90% and 32% as molar percentage of total aldoses in C. closterium, T. pseudonana and S. costatum, respectively). A strong reduction in glucose was found in C. closterium, but not in T. pseudonana and S. costatum, under P-depleted conditions. Species-specific variations in the amount and aldose signatures of the released polysaccharides according to nutrient status and growth conditions can provide useful insights on the production and persistence of these organic compounds in the water column.
Science of The Total Environment 01/2006; 353(1-3):300-6. · 3.29 Impact Factor
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ABSTRACT: Oceanographic cruises were carried out monthly from June 1999 to July 2002 to follow the mucilage formation process in the Northern Adriatic Sea. Results show that in correspondence with these events the dinoflagellate Gonyaulax fragilis (Schütt) Kofoid was observed both in the water column and within mucilage aggregates. In the water column, increasing abundances were observed from May until July, with values never exceeding 8500 cells l(-1). Much higher densities were observed within superficial gelatinous aggregates (22800-3400000 cells l(-1)). In mucilage samples, a large number of decomposing cells were present, together with abundant alive cells, enveloped in exudates. G. fragilis isolated from mucilage samples was cultured in three different culture media; it was characterized by a low growth rate but it produced a high amount of polysaccharides. The highest yield both in terms of cell number and carbohydrate production was observed in the medium having the highest nitrogen and phosphorus content and the lowest N/P ratio. The monomeric composition of G. fragilis carbohydrates, compared with that of mucilage samples, showed that in both natural and cultured samples galactose was the most abundant sugar; in addition, an overall good correlation, especially between the monomeric carbohydrate composition of G. fragilis grown in f/2 medium and that of a mucilage sample in which this species was present in high density, was observed.
Science of The Total Environment 11/2005; 353(1-3):307-16. · 3.29 Impact Factor
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ABSTRACT: Conformational energy calculations and molecular dynamics investigations, both in water and in dimethyl sulfoxide, were carried out on the exopolysaccharide cepacian produced by the majority of the clinical strains of Burkholderia cepacia, an opportunistic pathogen causing serious lung infection in patients affected by cystic fibrosis, The investigation was aimed at defining the structural and conformational features, which might be relevant for clarification of the structure-function relationships of the polymer. The molecular dynamics calculations were carried out by Ramachandran-type energy plots of the disaccharides that constitute the polymer repeating unit. The dynamics of an oligomer composed of three repeating units were investigated in water and in Me2SO, a non-aggregating solvent. Analysis of the time persistence of hydrogen bonds showed the presence of a large number of favourable interactions in water, which were less evident in Me2SO. The calculations on the cepacian chain indicated that polymer conformational features in water were affected by the lateral chains, but were also largely dictated by the presence of solvent. Moreover, the large number of intra-chain hydrogen bonds in water disappeared in Me2SO solution, increasing the average dimension of the polymer chains.
Carbohydrate Research 05/2005; 340(5):1025-37. · 2.33 Impact Factor
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ABSTRACT: Light scattering and viscosity measurements were carried out on the previously chemically characterised exopolysaccharide produced by a strain of Burkholderia cepacia isolated from a cystic fibrosis patient. The same exopolysaccharide was also produced by other clinical strains in different laboratories. Therefore, the name Cepacian is now proposed for this exopolysaccharide. Experiments performed as a function of the ionic strength on the native polymer revealed a change in the overall shape of the polymer at low ionic strength. This behaviour was absent in the de-acetylated sample. Potentiometric titrations and light scattering experiments carried out on the acidic form of the native polymer revealed the formation of macromolecular aggregates with a stoichiometry n and 2n stabilised by interactions involving the uronic acid residues.
Carbohydrate Research 10/2003; 338(18):1861-7. · 2.33 Impact Factor
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ABSTRACT: Benthic mucilaginous aggregates are frequently formed in various parts of the Mediterranean basin, as in the Tyrrhenian and Adriatic Seas. Notwithstanding their wide spatial distribution, the role played by these aggregates in the biogeochemical cycling of organic matter is still largely unknown.The characteristics of the benthic aggregates examined in the present study showed that they are different from other mucilaginous aggregates, such as the “pelagic” ones that can form in the same areas in the water column and subsequently sediment to the seafloor. The aggregates are usually formed of structures of the filamentous macroalgae Acinetospora crinita, Chrysonephos lewisii and Nematochrysopsis marina. The elemental composition of the aggregates showed a marine macrophyte origin on the basis of the bulk organic matter content of the aggregates. Carbohydrates and proteins account for 26.6 to 55.9% of the organic carbon in the mucilage, respectively. Monosaccharide composition of exopolysaccharides in the mucilage aggregates revealed a characteristic pattern, with galactose, xylose or mannose and fucose as the major components. The relatively high content of deoxysugars is another distinctive feature. The abundant sulphate and uronic groups present in the polysaccharides in addition to their macromolecular dimensions and elongation contribute to inter-chain aggregation. Electron microscopic observations suggest that the polysaccharide fraction is the main macromolecular component in the formation of the persistent gel network in the aggregates.
Marine Chemistry 111:184-198. · 3.07 Impact Factor
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ABSTRACT: Urban air pollution originates from traffic, heating and industrial activities and it exposes several categories of workers to noxious chemicals; in recent years various surveys have been carried on taxi drivers, bus drivers, policemen, newspaper kiosks, fuel station workers and general population, for assessing exposure to main contaminants, benzene and PAHs in particular.
defining a specific sampling strategy for collecting an experimental data base for the assessment of potential population exposure to atmospheric particulate matter in the Muggia area (Trieste, North-East Italy).
A sample of 14 urban police officers working mainly on the roads and potentially subject to occupational exposure has been analyzed, as well as a sample of the municipal administrative personnel (13 people) working in indoor environments during the same sampling periods. Exposure has been monitored by personal samplers and high volume environmental samples; urinary levels of 1 OH-pyrene and creatinine were collected for each participant at the end of each sampling period.
PAHs analyses provided diagnostic ratios for identification of the sources of pollution. In general experimental BaP values stay below the environmental target value, with satisfactory agreement between environmental and personal monitoring. Levels of urinary 1 OH-pyrene for administrative personnel was detected always below the background value (0.089 micromoles/mole creatinine), while they are above the background and below the attention value for most of urban police officers.
Municipal police officers participating to the present study, while belonging to one of the categories of people most exposed to outdoor PM, do not show any worrying exposure to the considered chemicals associated to their occupational activity, in comparison to other factors, possibly associated to personal lifestyles.
Giornale italiano di medicina del lavoro ed ergonomia 33(4):435-43.
