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NANOPARTICLES ACTIVITY DISTURB XENOPUS LAEVIS EMBRYOGENESIS
No full textNanoparticles (NPs) have extensive industrial, biotechnological, and biomedical/pharmaceutical applications, leading to concerns over health risks to humans and biota. Because of their properties NPs are attractive for basic science also. Size, surface charge, geometry, and its modifications contribute to NPs toxicity. The aquatic environment is at risk of exposure to NPs, as it acts as a sink for environmental contaminants. There are insufficient evidence for environmental concentrations and derived harms for almost all NPs. This finding requires more standardised approaches for NPs hazard identification. The possibility to relate the data obtained in Xenopus laevis with higher vertebrates, including humans, makes it a convincing study model. Our aim is to evaluate the activity of three different commercial NPs: AgNPs, AuNPs and SiO2NPs, 20nm sized, on the embryogenesis of X. laevis. These commercial NPs were used as model to understand the possible consequences of similar NPs utilized in medicine. DLS and TEM was performed to characterize these NPs. The embryos were reared starting from st4/8 in FETAX containing 0.01, 1 and 5 mg/L NPs. All embryos were harvested at st46/47. The mortality, morphology, length, heartbeat and pigment distribution were statistically analyzed. Real Time-PCR were carried out from embryos st.46 to verify gene expression. Our data showed that all NPs, that we tested, aggregate in FETAX and do not cause mortality. Embryos treated with AuNPs are longer and bradycardic compared with control, whereas those treated with AgNPs or SiO2NPs are shorter and tachycardic (AgNPs).The pigment distribution and gene expressions are altered. In conclusion our studies indicate that the NPs that we tested affect embryonic development impairing the expression of genes involved in the early embryogenesis
Predicting chemical bioavailable concentrations in freshwater ecosystems for five european environmental scenarios
No full textAssessment of the effects of Cr, Cu, Ni, and Pb soil contamination by ecotoxicological tests
No full textThis study aimed to assess soil quality by chemical and ecotoxicological investigations and to check the correspondence between soil metal concentrations and ecotoxicity. For these purposes, surface soils collected at four adjacent roadside urban parks and at a former industrial area were characterized for
C/N, organic matter content, texture, and pH. Cr, Cu, Ni and Pb, chosen among the most representative soil metal contaminants, were measured as total content and as available and water
soluble fractions. In addition, the total concentrations of the investigated metals were used to calculate two chemical indices: the contamination and the potential ecological risk factors. The toxicity of the investigated soils was evaluated by an ecotoxicity test battery carried out on both soil samples (Vibrio fischeri, Heterocypris incongruens and Sinapis alba) and elutriates (Vibrio fischeri, Daphnia magna and Selenastrum capricornutum). The findings, both by the chemical and ecotoxicological approaches,
would suggest that the soils with high metal contamination pose ecological risks. On the other hand, moderately metal contaminated soils did not exclude soil ecotoxicity. In fact, toxic effects were also highlighted in soils with low metal content, toxicity being affected by metal availability and soil characteristics. Moreover, the results suggest the importance of using a battery of tests to assess soil ecotoxicity
From in field to in vitro: response to heavy metal environmental pollution in Leptodyctium riparium
No full textThis study evaluated the biological effects of heavy metal pollution of the heavily contaminated channels Regi Lagni, running through the so-called “terra dei fuochi” (South Italy), using the aquatic moss L. riparium. This species is a efficient bioindicator of heavy metal pollution, accumulating different heavy metals taken from the aquatic environment (Basile et al, .2011). Biological effects of heavy metal pollution were assessed by studying metal bioaccumulation, ultrastructural damage, oxidative stress, and stress gene expression. Experiments were performed both on samples exposed in field in moss bags and in vitro-cultured in conditions reproducing the heavy metal pollution. Three sites were chosen as representative of the extreme polluted conditions. In vitro samples were exposed to the same HM concentrations as measured in the 3 sites. The results showed severe ultrastructural damage, increase of ROS production, induction of antioxidant enzymes and expression of stress gene. Those changes were observed both in the samples collected from the polluted sites and in those in vitro treated with the same heavy metal concentrations as in the field. In the in vitro test all the considered parameters were severely affected, although at a lower extent in comparison with the field experiment. The results showed that in vitro studies are useful indicators of the role exerted by the different stressors in environmental conditions. In addition, these results suggest L. riparium as a model organism in biomonitoring projects and the ultrastructural, enzymatic and genetic responses as promising biomarkers of heavy metal toxicity
Ranges of nutrient concentrations in Quercus ilex leaves at natural and urban sites
No full textThe leaf nutrient concentrations and the N-to-nutrient ratios were analyzed to evaluate the nutritional status of holm oaks (Quercus ilex L.) experiencing various anthropogenic pressures.
Leaves (1 year old) of Q. ilex and surface soil (0–5 cm) surrounding the trees were collected at seven natural and seven urban sites in Campania Region (Southern Italy) and analyzed for the concentrations of macro (C, N, P, S) and micronutrients (Mn, K, Na, Cu, Mg, Ca, Fe, Zn). The available soil fraction of micronutrients was also evaluated. The nutrients showed different concentration ranges for the natural and the urban sites in the soil (total and available) and in the leaves, that we reported separately. Organic-matter content and macronutrient concentrations were higher in the natural soils, while the highest leaf N, S, and P concentrations were found at some urban sites. Concentrations of Cu, Na and Zn both in leaves and soil, and Mg and Fe in leaves from the urban sites appeared to be affected by air depositions. Manganese was the only micronutrient to show higher concentrations at the natural than at the urban sites, both in soil and leaves. For this nutrient, in addition, a relationship between leaf and available soil concentrations was found at the natural sites. The ratios between the concentrations of N and each studied nutrient in the leaves highlighted a different nutritional status between the plants from the natural and urban sites
Polycyclic aromatic hydrocarbon contamination in an urban area assessed by Quercus ilex leaves and soil
No full textWe investigated the PAH contamination of Naples urban area, densely populated and with high traffic flow, by analyses of environmental matrices: soil and Quercus ilex leaves. Being some PAHs demonstrated to have hazardous effects on human health, the accumulation of carcinogenic and toxic PAHs (expressed as B(a)Peq) was evaluated in the leaves and soil. The main sources of the PAHs were discriminated by the diagnostic ratios in the two matrices. The urban area appeared heavily contaminated by PAHs, showing in soil and leaves total PAH concentrations also fivefold higher than those from the remote area. The soil mainly accumulated heavy PAHs, whereas leaves the lightest ones. Median values of carcinogenic PAH concentrations were higher in soil (440 ng g− 1 d.w.) and leaves (340 ng g− 1 d.w.) from the urban than the remote area (60 and 70 ng g − 1 d.w., respectively, for soil and leaves). Also, median B(a)Peq concentrations were higher both in soil and leaves from the urban (137 and 63 ng g− 1 d.w., respectively) than those from the remote area (19 and 49 ng g − 1 d.w., respectively). Different from the soils, the diagnostic ratios found for the leaves discerned PAH sources in the remote and urban areas, highlighting a great contribution of vehicular traffic emission as main PAH source in the urban area
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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