Hidden secrets of the Northern Adriatic: "Tegnúe", peculiar reefs

Abstract Research carried out over the last 40 years has underlined the scientific importance of the rocky outcrops scattered on the Northern Adriatic Sea bed sometimes referred to as "tegnúe". The zoobenthic biocenoses developing over these peculiar geological formations are as extraordinary as they are unique. A study carried out for an entire year in two sampling stations, at different distances from the coast, revealed a very high number of zoobenthic species, including those which have now become rare and are therefore protected in Italian seas. The water turbidity of the northern Adriatic Sea greatly reduces the quantity of light reaching these outcrops, limiting the activity of autotrophic organisms only to sciaphilous genera. Thus, the most represented trophic categories of zoobenthos are suspension, especially filter feeders. Biodiversity values calculated for the communities of these particular reefs are far higher than normally found in the soft seabed in nearby areas, but even higher than in other coralligenous outcrops in other marine ecosystem in the world. The ecological role played by the tegnúe in the Northern Adriatic is extraordinary because as well as being true oases of biodiversity, they are areas naturally protected against bottom trawl-fishing. Thus, they offer shelter and reproduction sites for a number of fish and invertebrate species, including some under stress due to severe fishing pressure

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

d(CGGTGGT) forms an octameric parallel G-quadruplex via stacking of unusual G(:C):G(:C):G(:C):G(:C) octads

Among non-canonical DNA secondary structures, G-quadruplexes are currently widely studied because of their probable involvement in many pivotal biological roles, and for their potential use in nanotechnology. The overall quadruplex scaffold can exhibit several morphologies through intramolecular or intermolecular organization of G-rich oligodeoxyribonucleic acid strands. In particular, several G-rich strands can form higher order assemblies by multimerization between several G-quadruplex units. Here, we report on the identification of a novel dimerization pathway. Our Nuclear magnetic resonance, circular dichroism, UV, gel electrophoresis and mass spectrometry studies on the DNA sequence dCGGTGGT demonstrate that this sequence forms an octamer when annealed in presence of K+ or NH4+ ions, through the 5′-5′ stacking of two tetramolecular G-quadruplex subunits via unusual G(:C):G(:C):G(:C):G(:C) octads

The insertion of two 8-methyl-2′-deoxyguanosine residues in tetramolecular quadruplex structures: trying to orientate the strands

In this article, we report a structural study, based on NMR and CD spectroscopies, and molecular modelling of all possible d(TG3T) and d(TG4T) analogues containing two 8-methyl-2′-deoxyguanosine residues (M). Particularly, the potential ability of these modified residues to orientate the strands and then to affect the folding topology of tetramolecular quadruplex structures has been investigated. Oligodeoxynucleotides (ODNs) TMMGT (T12) and TMMGGT (F12) form parallel tetramolecular quadruplexes, characterized by an all-syn M-tetrad at the 5′-side stacked to all-anti M- and G-tetrads. ODNs TMGMT (T13) and TMGGMT (F14) form parallel tetramolecular quadruplexes, in which an all-anti G core is sandwiched between two all-syn M-tetrads at the 5′- and the 3′-side. Notably, the quadruplex formed by T13 corresponds to an unprecedented structure in which the syn residues exceed in number the anti ones. Conversely, ODN TGMGMT (F24) adopts a parallel arrangement in which all-anti G-tetrads alternate with all-syn M-tetrads. Most importantly, all data strongly suggest that ODN TMGMGT (F13) forms an unprecedented anti-parallel tetramolecular quadruplex in which G and M residues adopt anti and syn glycosidic conformations, respectively. This article opens up new understandings and perspectives about the intricate relationship between the quadruplex strands orientation and the glycosidic conformation of the residues

Autophagy is defective in collagen VI muscular dystrophies and its reactivation rescues myofiber degeneration

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Toxicity of fluoride to the freshwater mollusc Dreissena polymorpha: Effects on survival, histology and antioxidant enzyme activity

The sensitivity of the freshwater non-indigenous mollusc Dreissena polymorpha towards fluoride (F) toxicity was examined in short-term (96-hr LC50; lethal concentration fifty) and long-term (18 days) laboratory experiments. The results indicate that the species is very resistant to F in water, much more than other aquatic invertebrates. In addition, they indicate a concentration- and time-dependent induction of oxidative stress by F exposure and a consequent alteration of the activities of antioxidant enzymes such as superoxide dismutase and catalase. The activity of both of these enzymes progressively decreased with increase of the exposure period when the F concentration was kept constant. Moreover, the appearance of pyknotic nuclei, as well as positivity to TUNEL analysis (Terminal deoxynucleotidyl transferase dUTP nick end labelling) suggests activation of the apoptotic machinery in tissues of animals exposed to high F concentration. This result appears to be related to a sustained condition of oxidative stress

Influence of temperature on fluoride toxicity and bioaccumulation in the non-indigenous mollusc Dreissena polymorpha pallas, 1769

Fluoride toxicity and bioaccumulation tests (short- and long-term) were performed on the non-indigenous freshwater mollusc Dreissena polymorpha at two different temperatures: 17\ub10.5\ub0C and 22\ub10.5\ub0C. Concentrations that did not result in toxicity in short-term experiments (96 h) induced effects over a longer period (17 weeks), especially at the warmest temperature, highlighting the role of this parameter. Fluoride bioaccumulation increased linearly with increasing concentration and temperature, reaching 4202 \u3bcg F-/g dry weight in soft tissues only after 48 hours of exposure at 22\ub0C at a concentration of 640 mg F-/L. Comparing tolerance to fluoride and bioaccumulation values of this species with those of other freshwater invertebrates, D. polymorpha resulted to be much more resistant and revealed its capacity to accumulate a great quantity of this xenobiotic. Our results demonstrated that fluoride accumulation in the soft tissue of this animal was much higher (up to 1409.6 \u3bcg F-/g dry weight) than in its shell (up to 706.4 \u3bcg F-/g dry weight). If we consider this datum and the fact that D. polymorpha is widespread in many aquatic ecosystems around the world, representing a food source for many birds and other vertebrates, we have to worry about the possibility that it can represent a serious danger in view of fluoride biomagnification in the aquatic environment

Fluoride influences haemocytes functionality in the venus clam Venerupis philippinarum

Invertebrates rely only on innate immunity to cope with foreign, potentially pathogenic microorganisms having entered the organism and haemocytes play a pivotal role in immune responses, as they are involved in phagocytosis, encapsulation, secretion of lectins, cytokines and cytotoxic factors. Therefore, adverse effects on haemocytes can compromise the survival of the organism. In the present study, we analysed the effects of the exposure of haemocytes of the venus clam Venerupis philippinarum to fluoride on cell morphology and functionality. Indeed, the increasing concentration of fluoride in many aquatic ecosystems, as a consequence of human activities, is a matter of great concern and the main negative effect of fluoride are related to its inhibition of metabolic processes, such as glycolysis and protein synthesis. Haemocytes, collected from the adductor muscles, were exposed to NaF (10, 50 and 250 mg/L) in filtered seawater (FSW), for 60 min. We observed a significant (p < 0.01) increase in cell mortality, using the Trypan Blue assay, for all the concentrations used in our experiments. The Neutral Red assay indicated a decrease in the stability of the internal membranes after exposure to 250 mg/L as the dye, usually accumulating inside acid compartments, such as lysosomes, leaks from these compartments into the cytoplasm so that the cells assume a pinkish colour. We also reported a significant (p < 0.01) reduction in the fraction of phagocytosing cells which suggests an effect of fluoride ions on the cytoskeleton or the hampering of the interaction with foreign particles. The observed increase in the cell shape factor in haemocytes exposed to 250 mg/L, indicating a decrease in the capability of haemocytes to assume a spreading morphology, fits the former above hypothesis. Future experiments will be directed to assess further the effects of fluoride on haemocyte functionality

Comparison of biomarker responses in Ruditapes philippinarum from seaward and landward sites in the Lagoon of Venice

A multibiomarker approach was used to assess effects of different environmental conditions in the clam Ruditapes philippinarum from the Lagoon of Venice. Bivalves were monthly (March 2009-February 2010) collected in two sites of the Lagoon differently influenced by both anthropogenic impact and natural conditions: a seaward site (Punta Sabbioni, PS) located near the lagoon inlet of Lido and influenced by intense passage of ships, and a landward site (Canale Dese, CD) influenced by both riverine inputs and agricultural waste waters. Water temperature, pH and salinity values were recorded, and chlorophyll a concentrations and sediment grain size and organic matter content were determined at the two sampling sites. The following biomarkers were measured at both cellular/tissue and organism level: total haemocyte count (THC), endocytotic and haemolymph lysozyme activities, gill acetylcholinesterase (AChE) activity, condition index (CI) and survival-in-air. Although a similar pattern of variation in THC values was observed at the two sites, THC was generally lower in clams from CD. From April to July, clams from PS showed a significantly higher endocytotic activity, whereas lysozyme activity was generally (8 out of 10 months) lower at PS. Clams from CD showed a reduced AChE activity in most samplings. As for the CI, it was significantly higher in PS clams in April, May, June, January and February. Lastly, the resistance to air exposure of clams from CD was shown to increase significantly with respect to that of animals from PS in 7 out of 10 months. Immunomarker responses highlighted an overall better condition for clams from PS and suggested a reduced immunosurveillance in clams from CD. The lower AChE activity recorded in clams collected at CD indicated a possible exposure of bivalves to neurotoxic compounds due to drainage waters from agricultural land. Interestingly, a different response was provided by the two biomarkers measured at organism level, CI increasing and survival-in-air decreasing in PS clams. Overall, the present study promotes the use of a multibiomarker approach in assessing ecological quality in estuarine systems worldwide