Toxicological effects and bioaccumulation of fullerene C60 (FC60) in the marine bivalve Ruditapes philippinarum.

Abstract Fullerene C60 (FC60), with its unique physical properties, has been used in many applications in recent decades. The increased likelihood of direct release into the environment has raised interest in understanding the biological effects of FC60 to aquatic organisms. Nowadays, only few studies have analysed FC60 effects and bioaccumulation in marine organisms following in vivo exposure. To provide new data about FC60 toxicity, Ruditapes philippinarum was selected as target species to assess potential adverse effects of the contaminant. Clams were exposed for 1, 3 and 7 days to predicted environmental concentrations of FC60 (1 and 10 μg/L) and cellular and biochemical responses were evaluated in clams' gills, digestive gland and haemolymph. The FC60 content in gills and digestive gland was determined in all experimental conditions after 7 days of exposure. Results showed an increase in oxidative stress. In particular, a significant modulation in antioxidant enzyme activities, and changes in glutathione S-transferase activity were observed in gills. Moreover, damage to lipids and proteins was detected in FC60-treated (10 µg/L) clams. In digestive gland, slighter variations in antioxidant enzyme activities and damage to molecules were detected. CAT activity was significantly affected throughout the exposure, whereas damage to lipids was evident only at the end of exposure. FC60 accumulation was revealed in both gills and digestive gland, with values up to twelve-fold higher in the latter. Interestingly, haemolymph parameters were slightly affected by FC60 compared to the other tissues investigated. Indeed, only Single Cell Gel Electrophoresis and Neutral Red uptake assays showed increased values in FC60-exposed clams. Moreover, volume and diameter of haemocytes, haemocyte proliferation, and micronucleus assay highlighted significant variations in treated clams, but only in the first phases of exposure, and no changes were detected after 7 days. Our results suggested clam gills as the target tissue for FC60 toxicity under the exposure conditions tested: the high damage detected to lipids and proteins could contribute to long-term problems for the organism

Long-term effects of fishing on physiological performance of the Manila clam (Ruditapes philippinarum) in the Lagoon of Venice

The Manila clam (Ruditapes philippinarum) is an important economic resource for fisheries in the Lagoon of Venice, where this species is fished and farmed. With the aim of evaluating possible fishing-induced long-term effects undergone by clam populations subjected to fishing efforts, physiological biomarkers were measured at organism level (clearance and respiration rates, scope for growth and survival-in-air test). Clams were collected on a seasonal basis from sites characterized by various fishing management practices: a free fishing area at S. Angelo and an area licensed for clam farming at Chioggia, where a non-fishing sub-area was established. R. philippinarum collected at S. Angelo generally showed reduced filtering activity and higher oxygen consumption, revealing general worsening in clam well-being in comparison with individuals from both Chioggia areas. This condition, resulting in lower standardized scope for growth values, may be explained by both environmental and fishing effort differences. Comparing Chioggia samples, better physiological performances were exhibited by clams from the non-fishing area, though no significant differences were observed. In winter, the survival-in-air test revealed the detrimental effects of fishing on clams, whereas in the other seasons this response generally seemed to be mostly related to other exogenous and endogenous factors. Although differences among sites and seasons were always statistically significant, all physiological parameters indicate the great tolerance of R. philippinarum to changing environmental conditions.European Commission [99/062

A multibiomarker approach in clams (Ruditapes philippinarum) for a toxicological evaluation of dredged sediments

The Lagoon of Venice is often dredged for channel maintenance. To avoid harmful consequences to the ecosystem, a proper disposal of bottom sediments requires a preliminary evaluation of its potential toxicity before excavation. Here we evaluated the effects of polluted sediments on clams (Ruditapes philippinarum) using a multibiomarker approach. Bivalves were exposed for 3 and 14 days to five sediment samples collected along a navigation canal between Venice historical centre and the industrial area of Porto Marghera. Immunological, antioxidant, detoxification, and neurotoxicity biomarkers were analysed in haemolymph, gill, and digestive gland. As a control, sediment collected far from pollution sources was used. Two experiments were performed to assess potential seasonal/gametogenic influence in clam sensitivity. A different response of clam biomarkers was observed during the two experiments and among sampling sites. Clams’ digestive gland resulted to be the most sensitive tissue analysed showing significant differences among sites in all biomarkers analysed. Greater differences were present due to seasonality rather than exposure. The concentrations of metals and organic pollutants increased from the city centre to the industrial area, highlighting the influence that industrial activities had on the lagoon ecosystem. However, bioaccumulation in clams did not follow the same clear pattern, suggesting low bioavailability of compounds due to relatively high organic matter content. Biomarkers modulation was mainly driven by metals, both present in sediments and bioaccumulated. In comparison, effects of organic pollutants on the biomarkers tested were negligible. Other sources of contamination not investigated (e.g. pesticides) were suggested by neurotoxicity biomarkers alteration

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file

First Evidence of Immunomodulation in Bivalves under Seawater Acidification and Increased Temperature

Water acidification, temperature increases and changes in seawater salinity are predicted to occur in the near future. In such a global climate change (GCC) scenario, there is growing concern for the health status of both wild and farmed organisms. Bivalve molluscs, an important component of coastal marine ecosystems, are at risk. At the immunological level, the ability of an organism to maintain its immunosurveillance unaltered under adverse environmental conditions may enhance its survival capability. To our knowledge, only a few studies have investigated the effects of changing environmental parameters (as predicted in a GCC scenario) on the immune responses of bivalves. In the present study, the effects of both decreased pH values and increased temperature on the important immune parameters of two bivalve species were evaluated for the first time. The clam Chamelea gallina and the mussel Mytilus galloprovincialis, widespread along the coast of the Northwestern Adriatic Sea, were chosen as model organisms. Bivalves were exposed for 7 days to three pH values (8.1, 7.7 and 7.4) at two temperatures (22 and 28°C). Three independent experiments were carried out at salinities of 28, 34 and 40 PSU. The total haemocyte count, Neutral Red uptake, haemolymph lysozyme activity and total protein levels were measured. The results obtained demonstrated that tested experimental conditions affected significantly most of the immune parameters measured in bivalves, even if the variation pattern of haemocyte responses was not always linear. Between the two species, C. gallina appeared more vulnerable to changing pH and temperature than M. galloprovincialis. Overall, this study demonstrated that climate changes can strongly affect haemocyte functionality in bivalves. However, further studies are needed to clarify better the mechanisms of action of changing environmental parameters, both individually and in combination, on bivalve haemocytes

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements