Anthropogenic effects on digestive gland of Pinna nobilis using oxidative stress biomarkers

The fan mussel Pinna nobilis L. is the largest endemic bivalve in the Mediterranean Sea under strict protection. The aim was to determine the effects of anthropogenic activity on antioxidant and oxidative stress biomarkers in digestive gland of P. nobilis. Antioxidant enzyme activities and protein oxidation were significantly increased in mussels sampled in the impacted area. The anthropogenic activities induced a situation of oxidative stress in P. nobilis, resulting in an antioxidant response and in an increased protein oxidatio

Understanding the twist-bend nematic phase: the characterisation of 1-(4-cyanobiphenyl-4'-yloxy)-6-(4-cyanobiphenyl-4'--yl)hexane (CB6OCB) and comparison with CB7CB

The synthesis and characterisation of the nonsymmetric liquid crystal dimer, 1-(4-cyanobiphenyl-40-yloxy)-6- (4-cyanobiphenyl-40-yl)hexane (CB6OCB) is reported. An enantiotropic nematic (N)–twist-bend nematic (NTB) phase transition is observed at 109 1C and a nematic–isotropic phase transition at 153 1C. The NTB phase assignment has been confirmed using polarised light microscopy, freeze fracture transmission electron microscopy (FFTEM), 2H-NMR spectroscopy, and X-ray diffraction. The effective molecular length in both the NTB and N phases indicates a locally intercalated arrangement of the molecules, and the helicoidal pitch length in the NTB phase is estimated to be 8.9 nm. The surface anchoring properties of CB6OCB on a number of aligning layers is reported. A Landau model is applied to describe high-resolution heat capacity measurements in the vicinity of the NTB–N phase transition. Both the theory and heat capacity measurements agree with a very weak first-order phase transition. A complementary extended molecular field theory was found to be in suggestive accord with the 2H-NMR studies of CB6OCB-d2, and those already known for CB7CB-d4. These include the reduced transition temperature, TNTBN/TNI, the order parameter of the mesogenic arms in the N phase close to the NTB–N transition, and the order parameter with respect to the helix axis which is related to the conical angle for the NTB phase.Postprint (published version

No habitat preference in mixed meadows and rocky bottoms for Mediterranean Labridae and Sparidae fish species

Fish species composition, abundance, diversity and niche breadth of Mediterranean littoral communities have been assessed for two types of habitat: rocky bottoms and mixed meadows of Posidonia oceanica (L.) Delile, 1813 and rocks. Labridae and Sparidae species have been considered to test differences in abundances between both habitats by means of underwater visual census. Data obtained suggests that these fish assemblages are very similar, and there are no significant differences in the niche breadth of both habitats. Differences in physical structure of the habitats are not enough to produce differences in the fish assemblages observed. A high fishing pressure in the study area may be removing the predator fish species, and consequently determining the species composition and abundance for rocky bottoms.Se ha estudiado la composición específica, la abundancia, la diversidad y la amplitud de nicho de dos comunidades ícticas mediterráneas mediante censos visuales en dos tipos de hábitat: fondos rocosos y fondos mixtos de Posidonia oceanica (L.) Delile, 1813 y roca. Se han observado especies de lábridos y espáridos y no se han encontrado diferencias significativas en las variables analizadas de estas comunidades en ambos hábitats. Las diferencias en la estructura física de los dos tipos de hábitat no son suficientes para justificar la aparición de variaciones significativas en las comunidades ícticas estudiadas. Un factor condicionante puede ser la elevada tasa de presión pesquera, que elimina las especies depredadoras y determinaría la composición específica y la abundancia de peces en los fondos rocosos.Instituto Español de Oceanografí

Distinctive dielectric properties of nematic liquid crystal dimers

We provide an overview of the effect of the molecular structure on the dielectric properties of dimers exhibiting nematic and twist-bend nematic phases with special focus on how the conformational distribution changes are reflected by the dielectric behaviour. Nematic dimers show distinctive dielectric properties which differ from those of archetypical nematic liquid crystals, as for example, unusual temperature dependence of the static permittivity or dielectric spectra characterised by two low-frequency relaxation processes with correlated strengths. The interpretation of such characteristic behaviour requires that account is taken of the effect of molecular flexibility on the energetically favoured molecular shapes. The anisotropic nematic interactions greatly influence the conformational distribution. Dielectric behaviour can be used to track those conformational changes due to dependence of the averaged molecular dipole moment on the averaged molecular shape. Results for a number of dimers are compared and analysed on the basis of the influence of details of the molecular structure, using a recently developed theory for the dielectric properties of dimers.Postprint (author's final draft

Microwave-Assisted Conversion of Levulinic Acid to γ-Valerolactone Using Low-Loaded Supported Iron Oxide Nanoparticles on Porous Silicates

The microwave-assisted conversion of levulinic acid (LA) has been studied using low-loaded supported Fe-based catalysts on porous silicates. A very simple, productive, and highly reproducible continuous flow method has been used for the homogeneous deposition of metal oxide nanoparticles on the silicate supports. Formic acid was used as a hydrogen donating agent for the hydrogenation of LA to effectively replace high pressure H2 mostly reported for LA conversion. Moderate LA conversion was achieved in the case of non-noble metal-based iron oxide catalysts, with a significant potential for further improvements to compete with noble metal-based catalyst

Microplastic ingestion in commercial fish species Boops boops, sardine Pilchardus and Engraulis encrasicolus in the western Mediterranean sea: MEDIAS SURVEY

Microplastic ingestion was assessed for three commercial fish species in the western Mediterranean Sea: Boops boops, Sardina pilchardus and Engraulis encrasicolus during the 2015 Spanish MEDIAS survey. Gastrointestinal tracts of 183 fish from 16 sites were examined. A total of 42 microplastics were found in the stomach contents of 31 individuals from all three species. B. boops was found to have ingested the most items (27%). No significant differences between abundance of ingested microplastics and spatial distribution of the sites were found, although it does appears microplastics are common in the food web of each species along the eastern coast of Spain

Biological effects of PAHs and heavy metals in Mytilus galloprovincialis: Assessment of the petrochemical industry in the Sicilian Coast, Italy

The use of biomarkers to analyze the effects of exposure to chemical contaminants in the aquatic environment is more extended nowadays. Mussels are sedentary filter-feeding organisms which may be exposed to large amounts of chemical pollutants. Mussels are prone to bioaccumulation and magnification of contaminants. In the present work, biological effects of environmental pollution were evaluated, mainly related to presence of PAHs and heavy metals, through several antioxidants and detoxification biomarkers in mussels (Mytilus galloprovincialis) from three areas located in the Eastern coastline of Sicily (Italy), previously transplanted (active biomonitoring). One of these three areas corresponds to the industrial harbour area between Augusta and Priolo, considered one of the most extensive areas of petrochemical industrial activity in Europe, severely contaminated by PAHs and heavy metals; a second point is located in Brucoli, littoral zone where the presence of xenobiotics in the environment is considered negligible; and a third point (reference site) from which proceed the pristine population of M. galloprovincialis. Changes at molecular and biochemical level in the tissue of the digestive gland were quantified. The results showed a significant increase (p<0.05) in the activity of the antioxidant enzyme catalase, the activity and expression of the detoxifying enzyme glutathione-S-transferase, and malondialdehyde levels, as a marker of lipid peroxidation, in mussels from the area of Priolo. The metallothioneins (MTs) gene expression was significantly induced in mussels (p<0.05) from Priolo when compared to those from the reference site. AChE was negatively affected by pollutants evidencing a decreased activity in Priolo (p<0.05). No significant differences were observed between the three sampling sites in the expression of the CYP3A1. In conclusion, the observed results demonstrate that the pollution associated with petrochemical industrial area (mainly of PAHs and heavy metals) causes the activation of the detoxification and antioxidant defence systems in the digestive gland of the mussels M. galloprovincialis, indicative of oxidative stress. This study provides further evidence of the criticality representing harbour areas, due to the presence of xenobiotics in high concentrations, which can accumulate in sediments and in living organisms due to the limited hydrodynamic inside harbour