Heavy metal bioaccumulation in honey bee matrix, an indicator to assess the contamination level in terrestrial environments.

The most significant risk factor for organisms living in an environment contaminated by heavy metals is the metal bioavailability. Therefore, an efficient ecotoxicological approach to metal contamination is the measure of bioaccumulation level in target organisms. In this work, we characterized the heavy metal bioaccumulation in honey bees, Apis mellifera ligustica, collected at 35 sites from Umbria (Central Italy). The comparison of our data with selected Italian investigations revealed metal bioaccumulation in honey bee matrix of the same order of magnitude, with Cd showing a higher variability. To generalize the results, we developed a Honeybee Contamination Index (HCI) based on metal bioaccumulation in honey bees. An application of the HCI to the present dataset revealed cases of low (sixteen sites), intermediate (eighteen sites), and high (one site) metal contaminations. The comparison of HCI values from the Umbrian dataset with values calculated for other Italian and European metadata showed that most of the Umbrian sites fell in the portion of low and intermediate contamination conditions. HCI represented a reliable tool that provided a piece of concise information on metal contamination in terrestrial environments. Parallel to this effort, we have determined, the metal concentrations in the airborne particulate matter (PM10) at three regional background-monitoring stations in Umbria. These stations are representative of the average air quality of the areas of the investigated apiaries. A comparative analysis of metal enrichment factors in PM10, and honey bees suggested that the contamination in the bees was related to the PM10 values only to a minor extent. On the other side, a clear enrichment of metals such as Cd, Mn, Zn, and Cu in the honey bees appeared to depend on very local conditions and was probably related to the use of pesticides and fertilizers, and the resuspension of the locally contaminated soils and agriculture residues.

Aerosol optical properties in the Arctic: The role of aerosol chemistry and dust composition in a closure experiment between Lidar and tethered balloon vertical profiles.

A closure experiment was conducted over Svalbard by comparing Lidar measurements and optical aerosol properties calculated from aerosol vertical profiles measured using a tethered balloon. Arctic Haze was present together with Icelandic dust. Chemical analysis of filter samples, aerosol size distribution and a full set of meteorological parameters were determined at ground. Moreover, scanning electron microscopy coupled with energy-dispersive X-ray (SEM-EDS) data were at disposal showing the presence of several mineralogical phases (i.e., sheet silicates, gypsum, quartz, rutile, hematite). The closure experiment was set up by calculating the backscattering coefficients from tethered balloon data and comparing them with the corresponding lidar profiles. This was preformed in three subsequent steps aimed at determining the importance of a complete aerosol speciation: (i) a simple, columnar refractive index was obtained by the closest Aerosol Robotic Network (AERONET) station, (ii) the role of water-soluble components, elemental carbon and organic matter (EC/OM) was addressed, (iii) the dust composition was included. When considering the AERONET data, or only the ionic water-soluble components and the EC/OM fraction, results showed an underestimation of the backscattering lidar signal up to 76, 53 and 45% (355, 532 and 1064 nm). Instead, when the dust contribution was included, the underestimation disappeared and the vertically-averaged, backscattering coefficients (1.45 ±â€¯0.30, 0.69 ±â€¯0.15 and 0.34 ±â€¯0.08 Mm-1 sr-1, at 355, 532 and 1064 nm) were found in keeping with the lidar ones (1.60 ±â€¯0.22, 0.75 ±â€¯0.16 and 0.31 ±â€¯0.08 Mm-1 sr-1). Final results were characterized by low RMSE (0.36, 0.08 and 0.04 Mm-1 sr-1) and a high linear correlation (R2 of 0.992, 0.992 and 0.994) with slopes close to one (1.368, 0.931 and 0.977, respectively). This work highlighted the importance of all the aerosol components and of the synergy between single particle and bulk chemical analysis for the optical property characterization in the Arctic.

Heavy metals bioaccumulation in selected tissues of red swamp crayfish: An easy tool for monitoring environmental contamination levels.

In this paper we explored the heavy metal bioaccumulation (Cd, Cu, Pb and Zn) in Procambarus clarkii, a crayfish recently suggested as a potential bioindicator for metals pollution in freshwater systems. The present study is focused on crayfishes populations caught in a heavily polluted industrial and in a reference sites (Central Italy), though the results are generalized with a thorough analysis of literature metadata. In agreement with the literature, the hepatopancreas (Hep, detoxification tissues) of the red swamp crayfish showed a higher concentration of heavy metals in comparison to the abdominal muscle (AbM, not detoxification tissues) in the sites under scrutiny. Hep/AbM concentration ratio was dependent on the specific metal investigated and on its sediment contamination level. Specifically we found that Hep/AbM ratio decreases as follows: Cd (11.7)>Cu (5.5)>Pb (3.6)>Zn (1.0) and Pb (4.34)>Cd (3.66)>Zn (1.69)>Cu (0.87) for the industrial and reference sites, respectively. The analysis of our bioaccumulation data as well as of literature metadata allowed to elaborate a specific contamination index (Toxic Contamination Index, TCI), dependent only on the bioaccumulation data of hepatopancreas and abdominal muscle. In the industrial site, TCI expressed values much higher than the unit for Cd and Cu, confirming that these metals were the main contaminants; in contrast for lower levels of heavy metals, as those observed in the reference site for Cu, Zn and Pb, the index provided values below unit. TCI is proposed as a useful and easy tool to assess the toxicity level of contaminated sites by heavy metals in the environmental management.

Deformities of chironomid larvae and heavy metal pollution: from laboratory to field studies.

Mouthpart deformities of Chironomus riparius larvae (Diptera) have been investigated to evaluate the toxic effects of contamination by heavy metals in the Genna Stream (Central Italy), situated in an area subjected to intensive swine farms (40000 heads). The livestock farming (fertirrigation) contributes to metal pollution of the Genna Stream with an increase of copper, zinc, cadmium, chromium and nickel in the sediments of the downstream stations. The incidence of mentum deformities was very high at all sampling stations, about 56%. The highest values of deformities were found in the intermediate river reach (St. 3: 65%) and in March (66%), mainly due to an increase in severe deformities. The high incidence of severe deformities (30%) is attributed to the high pollution level by heavy metals in the sediments, in particular to copper and zinc, which showed the highest average value at St. 3 and in March. This field study reflected the relationships between sediment metal concentrations and chironomid mouthpart deformities, previously observed in laboratory tests, and highlighted these deformities as toxicity endpoints. This feature paves the way for their use as an effective tool in freshwater bioassessment monitoring programs to evaluate the toxic effects of metal contamination in freshwater ecosystems.

Molecular-beam study of the ammonia-noble gas systems: characterization of the isotropic interaction and insights into the nature of the intermolecular potential.

We report new high resolution molecular beam experiments aimed at characterizing the intermolecular interaction in the NH(3)-Ng (Ng = He, Ne, Ar, Kr, Xe) weakly bound complexes. Integral cross section data are obtained over a sufficiently wide velocity range and with rotationally hot NH(3) molecules to produce (except for the NH(3)-He case) a well resolved "glory" quantum interference pattern. Data analysis, carried out by employing a recently proposed potential model, allows unique information on the absolute scale of the intermolecular interaction to be obtained both at long range and at the equilibrium distance. An extensive and internally consistent comparison with the behavior of the corresponding Kr-Ng systems is exploited in order to identify those cases where an interaction component due to charge transfer effects provides an appreciable intermolecular bond stabilization that is clearly distinct from and must be added to the standard van der Waals plus induction picture. The results of the present investigation extend the phenomenology of perturbative charge transfer effects in gas phase complexes involving hydrogenated molecules.

A bond-bond description of the intermolecular interaction energy: the case of the weakly bound acetylene-hydrogen complex.

A new semiempirical potential energy surface (PES) for the acetylene-hydrogen system has been derived by using the recently introduced bond-bond methodology. The proposed PES, expressed in an analytic form suitable for molecular dynamics simulations, involves a limited number of parameters, each one having a physical meaning and allowing the accurate description of the system also in the less stable configurations. The analysis of novel integral cross sections data, measured with nearly effusive molecular beams, combined with that of available pressure broadening coefficients of isotropic Raman lines at 143 K and IR lines at 173 and 295 K of C(2)H(2) in H(2), provides a test of the reliability of the proposed PES and suggests also some refinements. An extensive comparison with a recent ab initio potential is also exploited.

Molecular-beam scattering experiments and theoretical calculations probing charge transfer in weakly bound complexes of water.

We describe and analyze in depth a series of molecular beam scattering experiments, first reported by Aquilanti et al. (Angew. Chemie Int. Ed. 2005, 44, 2356.), proving that a measurable bond stabilization component beyond the van-der-Waals forces is present in the prototypal hydrophobic interaction of water with the noble gases (Ng). The experimental integral cross-section data, exhibiting a fully resolved "glory" interference pattern in the velocity dependence, are here quantitatively analyzed and characterized employing a recently proposed model potential. The stabilization component of the water-Ng bond has recently been attributed, through very accurate theoretical calculations and an unambiguous, model-free analysis of the electron density displacement, to a net electron transfer taking place from Ng to H(2)O. We review the theoretical analysis and discuss additional computational results, comparing them to experiment, that clarify the effect of charge transfer on the interaction energies.

A bond-bond description of the intermolecular interaction energy: the case of weakly bound N(2)-H(2) and N(2)-N(2) complexes.

The atom-bond pairwise additive approach, recently introduced by us to describe the potential energy surface for atom-molecule cases, is extended here for the first time to molecule-molecule systems. The idea is to decompose the van der Waals interaction energy into bond-bond pair contributions. This must be considered an improvement with respect to the familiar atom-atom pairwise additive representation since, still using a simple formulation, it indirectly accounts for three body effects. Such an approach also allows to include, in a straightforward way, the effect of the bond length on the intermolecular interaction energy. Cases of study are the weakly bound complexes involving the H(2) and N(2) molecules, namely N(2)-H(2) and N(2)-N(2), here described as a single bond-bond pair. For both systems ab initio calculations and experimental molecular beam scattering data, as well as second virial coefficients, have been employed to test the accuracy of the chosen representation of the interaction and to improve the obtained potential energy surfaces. The results of this work are important also for the generalization to the cases involving molecular ions and polyatomic molecules.

Atom-bond pairwise additive representation for cation-benzene potential energy surfaces: An ab initio validation study.

The achievement of extensive and meaningful molecular dynamics simulations requires both the detailed knowledge of the basic features of the intermolecular interaction and the representation of the involved potential energy surface in a simple, natural and analytical form. This double request stimulated us to extend to ion-molecule systems a semiempirical method previously introduced for the description of weakly interacting atom-molecule aggregates and formulated in terms of atomic species-molecular bond interaction additivity. The method is here applied to the investigation of the prototypical M(+)-C6H6 systems (M = Li, Na, K, Rb and Cs) and some of its predictions are tested against accurate ab initio calculations. Such calculations have been performed by employing the MP2 method and large basis sets, privileging the description of the metal atoms. The agreement between potential energy scans semiempirically obtained and ab initio results is good for all the investigated geometries, thus showing that the adopted representation is in general able to reproduce all the main features of the potential energy surface for these systems. The role of the various noncovalent interaction components, as a function of the geometry and of the intermolecular distance in the M(+)-C6H6 complexes, is also investigated for a more detailed assessment of the results of the semiempirical method.

A molecular dynamics investigation of rare-gas solvated cation-benzene clusters using a new model potential.

The main static and dynamic properties of some ionic heteroclusters, involving K+, C6H6, and Ar, have been investigated. A new representation of the intermolecular potential energy, which takes into account both electrostatic and non-electrostatic contributions to the overall noncovalent interaction, was used. Dynamical calculations were performed for a microcanonical ensemble. Particular attention was paid to the opening of the isomerization and dissociation processes for K+-C6H6-Ar(n) and to the formation of some of its fragments at increasing temperatures of the cluster considered.

Stereodynamic effects in the adsorption of propylene molecules on Ag(001).

We report on the experimental evidence of the role of rotational alignment of the gas-phase molecules in the interaction of propylene with Ag(001). Molecular alignment has been controlled by a velocity selection of the impinging molecules, flying in a supersonic seeded molecular beam. The experimental findings indicate that at low surface coverage the sticking probability is independent of molecular alignment, while when coverage exceeds few percent of a monolayer, molecules impinging rotating parallel to the surface (helicopter-like configuration) achieve a higher chance to be trapped than those which impinge rotating perpendicularly (cartwheels). The sudden appearance of a large stereodynamic effect suggests that the adsorption proceeds via a mobile precursor state and is tentatively correlated with a change in the configuration of the added propylene molecules, which adsorb tilted rather than flat at the surface.

A novel method for monitoring response to chemotherapy based on the detection of circulating cancer cells: a case report.

We describe a novel method for detecting micrometastasis in the blood stream of cancer patients based on RT-PCR amplification of tumor-associated carcinoembryonic antigen (CEA) mRNA. To increase sensitivity and specificity of RT-PCR, CEA transcript was selectively up-regulated in cancer cells by exposure of peripheral blood to non-toxic concentrations of staurosporine (ST). Thereafter, polyA(+) RNA was extracted from tumor cells captured by means of magnetic beads coated with a monoclonal antibody against a common human epithelial antigen. Finally, RNA was subjected to RT-PCR analysis of CEA transcript. Using this approach, we demonstrated an ST-mediated increase in CEA transcript in blood specimens collected from a patient with metastatic colon cancer before receiving treatment with 5-fluorouracil/leucovorin. After a few cycles of chemotherapy, CEA-positive tumor cells were no longer detected. Clinical follow-up of this patient indicated that treatment with chemotherapy induced a dramatic reduction in liver metastasis. Therefore, it can be hypothesized that lack of CEA transcript detection might be consistent with disappearance or at least marked reduction of circulating tumor cells.

Orientation of benzene in supersonic expansions, probed by IR-laser absorption and by molecular beam scattering.

This work represents the first experimental demonstration that planar molecules tend to travel as a "frisbee" when a gaseous mixture with lighter carriers expands into a vacuum, the orientation being due to collisions. The molecule is benzene, the prototype of aromatic chemistry. The demonstration is via two complementary experiments: interrogating benzene by IR-laser light and controlling its orientation by selective scattering on rare gas targets. The results cast new light on the microscopic mechanisms of collisional alignment and suggest a useful way to produce intense beams of aligned molecules, permitting studies of steric effects in gas-phase processes and in surface catalysis.

Staurosporine increases carcinoembryonic antigen expression in a human colon cancer cell line.

Staurosporine (ST), a protein kinase C inhibitor, was found to produce antitumor effects against C22.20, a clonal subline derived from colon cancer HT-29 line, selected for low expression of carcinoembryonic antigen (CEA). However, as assessed by FACS analysis using propidium iodide, no apoptosis or cell cycle alteration was found on day 3 after treatment of C22.20 cells with ST (1-100nM). Exposure of cells to graded concentrations of the drug (i.e., from 1 to 25nM) resulted in a concentration-dependent increase in the percentage of CEA positive cells, as determined by flow cytometric analysis. However, when higher concentrations (i.e. 50nM - 100nM) of ST were used, the percentage of CEA positive cells declined compared to that detected in 25nM-treated tumor. Since these results were obtained in a clonal cell population, it is reasonable to hypothesize that induction rather than selection mechanism is involved in this phenomenon. The potential clinical interest of the present findings stems from the consideration that treatment with ST or its derivatives could improve sensitivity and efficacy of diagnostic and/or immunotherapeutic approaches based on CEA molecules.

Drug-induced modulation of carcinoembryonic antigen (CEA) expression in neoplastic cells from a patient with rectal cancer.

Treatment with 5-fluorouracil (5-FU) or recombinant interferon-gamma (IFN), alone or in combination, was found to increase carcinoembryonic antigen (CEA) expression in several carcinoma cell lines. In this study we examined the in vitro effect of these agents on CEA expression of tumor cells, obtained from a patient operated for rectal cancer. The results showed that exposure of cancer cells to 5-FU or to IFN resulted in increased CEA levels in terms of percentage of CEA-positive cells and mean fluorescence values, as indicated by FACS analysis. However, drug combination did not induce CEA expression higher than that provided by single agents alone. Treatment with 5-FU or with IFN produced a reduction of the total number of viable cells. Moreover, Western blot analysis revealed that exposure of cancer cells to each drug was followed by a substantial increase of the total cellular CEA content. On the contrary, 5-FU in combination with IFN did not increase the expression of the antigen more than that obtained by single agents. Noteworthy, exposure of CEA-negative cells from adjacent normal rectal tissue to both agents alone or in combination, did not result in CEA induction. In conclusion, the present results suggest new approaches aimed at (a) increasing the sensitivity of diagnostic procedures based on detection of CEA-positive tumor cells; (b) facilitating the recognition of CEA-positive cancer cells by immune responses induced by anti-CEA peptide vaccines.

Effect of rifampin on CD1b expression and double-negative T cell responses against mycobacteria-derived glycolipid antigen.

Non-classical antigen-presentation by CD1 molecules expressed on cytokine-activated monocytes (CAM), and cell-mediated responses supported by double-negative (DN) and by CD8+ responder alphabeta T cells, are involved in host resistance against mycobacterial infections. The CD1b protein is responsible for presentation of non-peptide, lipid antigens to T cells. In this context, a pivotal role is played by induction of CD1b protein on the membrane of human monocytes activated by GM-CSF alone, and more efficiently by GM-CSF combined with IL-4. Rifampin (RFP), a drug which is extensively utilized for chemoprophylaxis or treatment of Mycobacterium tuberculosis, is known to reduce a number of B, or T cell-dependent responses. Therefore we undertook immunopharmacological studies on RFP, to determine the effects of this agent on human macrophage function, relative to antigen presentation by CD1b molecules and on DN T cell cytolytic function. The results showed that: (a) graded concentration of RFP (2 or 10 microg/ml) induced a significant increase of CD1b expression, in CAM as evaluated by FACS analysis; (b) RFP increased significantly the specific mAb binding to CD1b on CAM surface; (c) treatment of effector cells with RFP did not reduce DN T cell-mediated cytolysis against lymphoblastoid cells transfected with CD1b cDNA (C1R.b6 cells), pulsed with M. tuberculosis. These results suggest that RFP could be of potential value in improving mycobacterial antigen presentation without impairing responder T cell function.