Potential of PM-selected components to induce oxidative stress and root system alteration in a plant model organism

Over the last years, various acellular assays have been used for the evaluation of the oxidative potential (OP) of particular matter (PM) to predict PM capacity to generate reactive oxygen (ROS) and nitrogen (RNS) species in biological systems. However, relationships among OP and PM toxicological effects on living organisms are still largely unknown. This study aims to assess the effects of atmospheric PM-selected components (brake dust - BD, pellet ash - PA, road dust - RD, certified urban dust NIST1648a - NIST, soil dust - S, coke dust - C and Saharan dust - SD) on the model plant A. thaliana development, with emphasis on their capacity to induce oxidative stress and root morphology alteration. Before growing A. thaliana in the presence of the PM-selected components, each atmospheric dust has been chemically characterized and tested for the OP through dithiothreitol (DTT), ascorbic acid (AA) and 2′,7′-dichlorofluorescin (DCFH) assays. After the exposure, element bioaccumulation in the A. thaliana seedlings, i.e., in roots and shoots, was determined and both morphological and oxidative stress analyses were performed in roots. The results indicated that, except for SD and S, all the tested dusts affected A. thaliana root system morphology, with the strongest effects in the presence of the highest OPs dusts (BD, PA and NIST). Principal component analysis (PCA) revealed correlations among OPs of the dusts, element bioaccumulation and root morphology alteration, identifying the most responsible dust-associated elements affecting the plant. Lastly, histochemical analyses of NO and O2•− content and distribution confirmed that BD, PA and NIST induce oxidative stress in A. thaliana, reflecting the high OPs of these dusts and ultimately leading to cell membrane lipid peroxidation

Efficiency evaluation of food waste materials for the removal of metals and metalloids from complex multi-element solutions

Recent studies have shown the potential of food waste materials as low cost adsorbents for the removal of heavy metals and toxic elements from wastewater. However, the adsorption experiments have been performed in heterogeneous conditions, consequently it is difficult to compare the efficiency of the individual adsorbents. In this study, the adsorption capacities of 12 food waste materials were evaluated by comparing the adsorbents' efficiency for the removal of 23 elements from complex multi-element solutions, maintaining homogeneous experimental conditions. The examined materials resulted to be extremely efficient for the adsorption of many elements from synthetic multi-element solutions as well as from a heavy metal wastewater. The 12 adsorbent surfaces were analyzed by Fourier transform infrared spectroscopy and showed different types and amounts of functional groups, which demonstrated to act as adsorption active sites for various elements. By multivariate statistical computations of the obtained data, the 12 food waste materials were grouped in five clusters characterized by different elements' removal efficiency which resulted to be in correlation with the specific adsorbents' chemical structures. Banana peel, watermelon peel and grape waste resulted the least selective and the most efficient food waste materials for the removal of most of the elements

Monitoring and evaluation of Terni (Central Italy) air quality through spatially resolved analyses

A study of spatial variability of PM10 elemental components was conducted in Terni city (Central Italy), situated in an intramountain depression characterized by the presence of several particulate matter emission sources. The meteorological conditions of Terni basin limit the dispersion and enhance the accumulation of the atmospheric pollutants. Thanks to the utilization of new samplers (Smart Sampler), used for the first time and working in parallel at 23 sampling sites, spatially resolved data were obtained. Localizations of the samplers were chosen in order to evaluate the impact of different local PM10 sources. Chemical composition of the samples was determined in combination with a chemical fractioning procedure, that allowed us to discriminate watersoluble and residual fractions of analyzed elements in which proved to be a valuable approach for increasing selectivity of elements as source tracers. Spatial variability of elements underlined the contribution of local emission sources and the different dispersion capacity of each element. Terni city resulted to be an ideal area to test and validate a new experimental method for the acquisition of spatially resolved data providing the possibility to properly evaluate the spatial variability of PM10 and its chemical components

In-vivo exposure of a plant model organism for the assessment of the ability of PM samples to induce oxidative stress

This study aims to propose an innovative, simple, rapid, and cost-effective method to study oxidative stress induced by PM through in-vivo exposure of the plant model organism Arabidopsis thaliana. A. thaliana seedlings were exposed to urban dust certified for its elemental content and to PM2.5 samples collected in an urban-industrial area of Northern Italy. An innovative technique for the detachment and suspension in water of the whole intact dust from membrane filters was applied to expose the model organism to both the soluble and insoluble fractions of PM2.5, which were analyzed for 34 elements by ICP-MS. Oxidative stress induced by PM on A. thaliana was assessed by light microscopic localization and UV–Vis spectrophotometric determination of superoxide anion (O2−) content on the exposed seedlings by using the nitro blue tetrazole (NBT) assay. The results showed a good efficiency and sensitivity of the method for PM mass concentrations >20 μg m−3 and an increase in O2− content in all exposed seedlings, which mainly depends on the concentration, chemical composition, and sources of the PM administered to the model organism. Particles released by biomass burning appeared to contribute more to the overall toxicity of PM. This method was found to be cost-effective and easy to apply to PM collected on membrane filters in intensive monitoring campaigns in order to obtain valuable information on the ability of PM to generate oxidative stress in living organisms

Fungi and arsenic. Tolerance and bioaccumulation by soil saprotrophic species

Increasing arsenic environmental concentrations are raising worldwide concern for its impacts on human health and ecosystem functionality. In order to cope with arsenic contamination, bioremediation using fungi can represent an efficient, sustainable, and cost-effective technological solution. Fungi can mitigate arsenic contamination through different mechanisms including bioaccumulation. In this work, four soil saprotrophic fungi Absidia spinosa, Purpureocillium lilacinum, Metarhizium marquandii, and Cephalotrichum nanum, isolated from soils with naturally high arsenic concentrations, were tested for their ability to tolerate different sodium arsenite concentrations and accumulate As in different cultural conditions. pH medium after fungal growth was measured to study pH variation and metabolic responses. Arsenic bioaccumulation and its influence on the uptake of other elements were investigated through multi-elemental analysis using hydride generation atomic fluorescence spectrometry (HG-AFS), inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Considering the increasing interest in siderophore application for metal bioremediation, the production of siderophores and their affinity for both Fe and As were also evaluated. All species were able to tolerate and accumulate As in their biomass in all of the tested conditions and produced siderophores with different affinities for Fe and As. The results suggest that the tested fungi are attractive potential candidates for the bioremediation of As contaminated soil and worthy of further investigation

Evaluation of the Efficiency of Arundo donax L. Leaves as Biomonitors for Atmospheric Element Concentrations in an Urban and Industrial Area of Central Italy

Washed and unwashed Arundo donax L. (A. donax) leaves were analyzed for elements, and results were compared with element concentrations detected in river water and particulate matter (PM) Samples were collected along a river in an urban and industrial hot spot of Central Italy, where element concentrations show relevant spatial gradients both in air and river water. The aim of this study is to identify the role of the two environmental matrices on leaves composition. Element concentrations of washed and unwashed leaves were compared to differentiate between the superficial deposition and the uptake into leaf tissues of elements. Water-soluble and -insoluble element concentrations were measured in PM10 samples collected on membrane filters by using innovative high spatial resolution samplers. The comparison among leaf and atmospheric concentrations of PM10 elements showed a similar trend for Ni, Mo, Cr, Ti, and Fe, which are reliable tracers of the PM10 contribution by steel plant and vehicular traffic. Soluble species appeared to be mainly bounded into leaf tissues, while insoluble species were deposited on their surface. On the other hand, element concentrations detected in washed A. donax leaves were poorly correlated with those measured in river water samples. The obtained results proved that A. donax leaves can be used as reliable biomonitors for the evaluation of the atmospheric concentrations of some PM10 elemental components

Metal-phthalocyanine ordered layers on Au(110): Metal-dependent adsorption energy

Iron-phthalocyanine and cobalt-phthalocyanine chains, assembled along the Au(110)-(1×2) reconstructed channels, present a strong interaction with the Au metallic states, via the central metal ion. X-ray photoemission spectroscopy from the metal-2p core-levels and valence band high-resolution ultraviolet photoelectron spectroscopy bring to light signatures of the interaction of the metalphthalocyanine single-layer with gold. The charge transfer from Au to the molecule causes the emerging of a metal-2p core level component at lower binding energy with respect to that measured in the molecular thin films, while the core-levels associated to the organic macrocycle (C and N 1s) are less influenced by the adsorption, and the macrocycles stabilize the interaction, inducing a strong interface dipole. Temperature Programmed Desorption experiments and photoemission as a function of temperature allow to estimate the adsorption energy for the thin-films, mainly due to the moleculemolecule van der Waals interaction, while the FePc and CoPc single-layers remain adsorbed on the Au surface up to at least 820 K. © 2014 AIP Publishing LLC.Fil: Massimi, Lorenzo. Universita Di Roma. Departamento de Fisica; ItaliaFil: Angelucci, Marco. Universita Di Roma. Departamento de Fisica; ItaliaFil: Gargiani, Perluigi. Universita Di Roma. Departamento de Fisica; ItaliaFil: Betti, Maria Grazia. Universita Di Roma. Departamento de Fisica; ItaliaFil: Montoro, Silvia Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Física del Litoral; ArgentinaFil: Mariani, Carlo. Universita Di Roma. Departamento de Fisica; Itali

Test and optimization of a multi-modal phase-based x-ray microscope for soft tissue imaging

Tissue imaging is a pivotal component of both biomedical research and clinical practice. In order to identify tissue structures down to the cellular level, it requires the capability to image mm-size unstained tissue specimens with micron to sub-micron resolution. Tissue imaging is normally performed either using x-rays or visible light. While the latter is limited by light scattering in relatively thick tissues, the former often suffers from poor contrast in absorption-based systems. Phase-contrast x-ray microscopes exist but they often lack the required quantitativeness, entail acquisition times of the order of tens of hours for 3-D imaging and are limited to narrow fields of view. We propose a novel multi-modal phase-based x-ray microscope capable of imaging mm-thick tissue samples on a mm-size field of view using intensity-modulation masks. They act as optical elements allowing the quantitative retrieval of tissue properties such as transmission, refraction and scattering. Additionally, given that the system’s spatial resolution depends only on the mask aperture size, a multi-resolution approach is possible by selecting masks with aperture size matching the resolution requirements (micron and sub-micron) of specific samples. The design and optimization of the x-ray microscope is presented in this paper together with exemplar images of a thin foam sample resulting from the retrieval of the three contrast channels. The final paper will include details of the system parameter optimization (e.g., propagation distance, mask aperture and period), their effect on the retrieval algorithm and imaging performance as well as the first images of biological samples

Monitoring and Evaluation of Terni (Central Italy) Air Quality through Spatially Resolved Analyses

A study of spatial variability of PM10 elemental components was conducted in Terni city (Central Italy), situated in an intramountain depression characterized by the presence of several particulate matter emission sources. The meteorological conditions of the Terni basin limit the dispersion and enhance the accumulation of atmospheric pollutants. Thanks to the utilization of new smart samplers, used for the first time and working in parallel at 23 sampling sites, spatially resolved data were obtained. Localizations of the samplers were chosen in order to evaluate the impact of different local PM10 sources. Chemical composition of the samples was determined in combination with a chemical fractioning procedure that allowed us to discriminate water-soluble and residual fractions of analyzed elements in which proved to be a valuable approach for increasing selectivity of elements as source tracers. Spatial variability of elements underlined the contribution of local emission sources and the different dispersion capacity of each element. The city of Terni resulted to be an ideal area to test and validate a new experimental method for the acquisition of spatially resolved data providing the possibility to properly evaluate the spatial variability of PM10 and its chemical components

Bismuth exposure affects morpho-physiological performances and the ionomic profile in garden cress (Lepidium sativum L.) plants

Environmental pollution caused by heavy metals has long been considered a relevant threat to ecosystem survival and human health. The use of safer substitutes for the most toxic heavy metals in many industrial applications is discussed as a potential way to face this issue. In this regard, Bi has been proposed for replacing Pb in several production processes. However, few literature records reported on the effects of Bi on living organisms, particularly on plants. In this study, garden cress (Lepidium sativum L.) plants were exposed to different concentrations of Bi nitrate added to soil in growth chambers for 21 days. Results evidenced the toxic effect of Bi on shoot growth, regardless of the Bi nitrate concentration in the soil, paralleled by a similar reduction in the chlorophyll and carotenoid content, a decrease in the nitrogen balance index values, and an impairment of the photosynthetic machinery evaluated by chlorophyll fluorescence image analysis. The presence of Bi in the soil was shown to affect element accumulation in roots and translocation to shoots, with micronutrient content particularly reduced in the leaves of Bi-treated plants. A dose-dependent plant accumulation of Bi to metal concentration in the soil was observed, even if very low metal bioconcentration ability was highlighted. The reduced Bi translocation from roots to shoots in plants exposed to increasing Bi concentrations in the soil is discussed as a possible defense mechanism likely associated with the observed increase of anthocyan and flavonol contents and the activation of photoprotection mechanisms preventing higher damages to the photosynthetic apparatus