1,354,109 research outputs found
Trophic status and meiofauna biodiversity in the Northern Adriatic Sea: insights for the assessment of good environmental status
No full textThe Descriptor 5 (Eutrophication) of the EU Marine Strategy Framework Directive aims at preventing the negative effects of eutrophication. However, in coastal systems all indicators based on water column parameters fail in identifying the trophic status and its effects on biodiversity and ecosystem functioning. We investigated benthic trophic status, in terms of sedimentary organic matter quantity, composition and quality, along with meiofaunal abundance, richness of taxa and community composition in three coastal sites (N Adriatic Sea) affected by different levels of anthropogenic stressors. We show that, on the basis of organic matter quantity and composition, the investigated areas can be classified from oligo-to mesotrophic, whereas using meiofauna as a descriptor, their environmental quality ranged from sufficient to moderately impacted. Our results show that the benthic trophic status based on organic matter variables, is not sufficient to provide a sound assessment of the environmental quality in marine coastal ecosystems. However, data reported here indicate that the integration of the meiofaunal variable allows providing robust assessments of the marine environmental statu
Diversity of microbiomes associated with benthic invertebrates inhabiting Antarctic ecosystems
No full textIl numero sempre più alto di studi condotti sui microbiomi ha evidenziato l’importanza che queste associazioni rivestono nello sviluppo, nella salute e nella fitness degli organismi con cui i microbiomi vivono associati. In ambienti estremi come l’Antartide, i microbiomi sembrano avere un’importanza cruciale nel creare interazioni fondamentali per l’adattamento dei loro ospiti. Gli obiettivi di questa tesi sono: i) studiare la biodiversità dei microbiomi associati a diversi invertebrati marini antartici, ii) esplorarne l’origine, confrontando i microbiomi associati agli organismi con le comunità batteriche che abitano nei sedimenti circostanti, e iii) verificare se i fattori ambientali svolgano un ruolo attivo nel modellare la loro composizione tassonomica. I risultati hanno mostrato che, nonostante i microbiomi associati ai policheti antartici (Leitoscoloplos geminus, Aphelocaeta palmeri, Aglaophamus trissophyllus) possano variare in modo significativo tra gli individui, è possibile individuare dei core, sia a livello intraspecifico sia interspecifico, che contribuiscono significativamente all'intera comunità batterica associata. I taxa batterici associati ai policheti sono completamente diversi da quelli presenti nei sedimenti circostanti, suggerendo una potenziale trasmissione verticale o diverse capacità adattative dei microbiomi ai due diversi “habitat”. Molteplici fattori (i.e., non solo fattori ambientali ma anche quelli biologici come lo stato fisiologico e le abitudini di alimentazione) influenzano, a diversi gradi, la composizione tassonomica dei microbiomi associati ai policheti antartici. Nella stella marina antartica Odontaster validus la posizione geografica è il principale fattore che spiega le differenze trovate nella composizione tassonomica dei microbiomi, sebbene siano state riscontrate alcune somiglianze tra individui raccolti in luoghi diversi, suggerendo la presenza di altri fattori in grado di selezionare comunità batteriche simili. La presenza esclusiva di batteri specifici associati a stelle marine che vivono in determinate aree suggerisce una potenziale trasmissione orizzontale dei microbiomi, probabilmente acquisiti attraverso diverse abitudini alimentari che le stelle marine hanno sviluppato nelle suddette aree. Questa tesi di dottorato fornisce nuove informazioni sui microbiomi antartici, evidenziando una forte variabilità della loro composizione e complessità delle relazioni con gli ospiti esaminati, potenzialmente dovute, oltre ai fattori ambientali, anche alle caratteristiche biologiche degli ospiti.Growing studies on host-associated microbiomes are highlighting the important role of microbes in the development, health and fitness of their hosts. This might be particularly true in remote and extreme environments, such as the Antarctic ecosystem, where the host and its microbiome could evolve together establishing peculiar and close interactions. This study aims: i) to investigate the biodiversity of microbiomes of different Antarctic invertebrates, ii) to explore the potential sources of the host-associated microorganisms by comparing them with microbial communities inhabiting the surrounding sediments, and iii) to verify the role of environmental setting in shaping their taxonomic composition. Results revealed that microbiomes of Antarctic polychaetes (Leitoscoloplos geminus, Aphelocaeta palmeri, Aglaophamus trissophyllus) showing significant variability among individuals, but that both intra-specific and inter-specific core microbiomes contribute for a significant fraction to the whole microbial assemblage. Bacteria associated with polychaetes were completely different from those in the surrounding sediments, suggesting a potential vertical transmission or the presence of different adaptative/selective conditions of the two “habitats”. Multiple factors (i.e., not only environmental factors but also biological ones such as physiological state and feeding habits) can influence to different extent the taxonomic composition of microbiomes associated with Antarctic polychaetes. In the Antarctic sea star Odontaster validus, the geographic location was identified as the main factor influencing the taxonomic composition of microbiomes, but this was not a general rule. In fact, high similarities were found among microbiomes of individuals collected in different locations, suggesting the presence of other drivers able to select similar microbial communities. The presence of exclusive bacterial families in sea-star microbiomes suggests a potential horizontal transmission of bacterial taxa, probably acquired through different feeding habits that the sea star might have developed in the different basins. This PhD thesis provided new information on Antarctic microbiomes, highlighting a strong variability of their composition and complexity of the relationships with the investigated hosts, potentially due to, besides environmental settings, also to hosts’ biological features
New data concerning the antianaphylactic and antihistaminic activity of nimesulide
No full textThe time to respiratory crisis in ovalbumin-sensitised guinea-pigs following exposure to aerosol administered antigen was dose dependently delayed by inhalation of nimesulide (0.1% to 1%), whereas indomethacin had no effect. At the same time, nimesulide significantly reduced blood histamine concentrations, in contrast to the slight increase observed with indomethacin. In human bronchial muscle preparations, nimesulide, but not indomethacin, antagonised H1-histamine-receptor activation by histamine and was without effect on acetylcholine-induced responses. Bronchoconstriction was also elicited in anaesthetised guinea-pigs by intravenous acetaldehyde (5% in saline, 1 ml/kg). This effect, which is paralleled by a rise in blood histamine concentrations, was significantly attenuated by inhaled nimesulide (0.1% to 1%), but not by indomethacin (1%). These data, which further support the antihistaminic and antiallergic activity of nimesulide, may have therapeutic relevance in patients who are affected by inflammation of the respiratory tract and who also have a history of allergic bronchoconstriction
Antianaphylactic and antihistaminic activity of the non-steroidal anti-inflammatory compound nimesulide in guinea-pig
No full textNimesulide (4-nitro-2-phenoxymethane sulfonanilide, Aulin, Mesulid) is a non-steroidal anti-inflammatory compound which shows antihistaminic activity and inhibits the immune release of histamine. The antihistaminic activity of this compound is specific for H1-receptor and has been demonstrated on isolated strips of guinea-pig trachea and on histamine-induced multiphasic inotropic response in left atria of guinea pig electrically driven. The effect of nimesulide is of non competitive type and, at the concentration of 1 x 10(-5) mol/l, is nearly 2 time less potent than pyrilamine (mepyramine) at 1 x 10(-6) mol/l. Nimesulide (1.6 mumol/kg i.v.) inhibits both bronchoconstriction (69%) and TXB2 formation (93%) induced by histamine (0.05 mumol/kg i.v.) in anaesthetized guinea-pigs. In contrast indomethacin (1.6 mumol/kg i.v.) decreases the generation of TXB2 (89%) without affecting the enhancement in tracheal insufflation pressure induced by histamine. In actively sensitized guinea-pigs both nimesulide and indomethacin protect the animals from deadly anaphylactic crisis. The rise in tracheal pressure induced by the antigenic challenge is inhibited of 80% and 63% respectively by nimesulide and indomethacin (6.4 mumol/kg i.v.). At this dose the two compounds reduced of 90% approximately the immunological release of TXB2 in the circulation. The release of histamine, induced by the anaphylactic reaction caused in perfused lungs obtained from actively sensitized guinea-pigs, is lessened by nimesulide (EC50 = 3.06; fid. lim. 2.59-3.63 mumol/l) and potentiated by indomethacin (EC50 = 0.89; fid. lim. 0.67-1.17 mumol/l).(ABSTRACT TRUNCATED AT 250 WORDS
Nematode biodiversity and benthic trophic state are simple tools for the assessment of the environmental quality in coastal marine ecosystems
No full textA high biodiversity is essential to guarantee the stability and functioning of coastal marine ecosystems. In this perspective, the Marine Strategy Framework Directive provides prescriptions to maintain (or restore) marine biodiversity in order to achieve a Good Environmental Status (GES). Eutrophic conditions - as determined by the accumulation of sedimentary organic matter (OM) – are often associated with biodiversity loss, so that eutrophic conditions are often considered a pre-requisite or a proxy for degraded ecological conditions. The aim of this study was to investigate the feasibility of the combined use of benthic trophic status and nematode biodiversity as integrated indicators of the environmental status of marine coastal ecosystems. To achieve this objective, we investigated nematode species diversity and assemblage composition in three areas of the Adriatic Sea, characterised by different OM quantity and biochemical composition (as proxy of sedimentary trophic status) and affected by different levels of anthropogenic impact. We show that, on the basis of OM quantity and biochemical composition, the investigated sites can be classified from oligo- to meso-trophic, whereas the analysis of nematode biodiversity indicates that the ecological quality status (EQS) ranged from bad to moderately impacted. This result provides evidence that trophic status and environmental quality assessments are not interchangeable tools for the assessment of marine ecosystems EQS. Rather they should be considered as complementary proxies for the overall assessment of the (good) ecological status. Data reported here also indicate that the loss of benthic biodiversity, whatever the source of disturbance, may be associated to a decrease of the functional diversity (either as feeding and life strategies traits), which might have important consequences on ecosystems functioning. Our results suggest that the GES cannot be defined uniquely in terms of sedimentary trophic status, especially when many other multiples stressors can contribute to determine the overall environmental quality of the investigated ecosystems. Nematode biodiversity is highly sensitive to differences in ecological conditions at different spatial and temporal scales and it can provide reliable and complementary information for the assessment of the environmental status in marine coastal sediments
Prestazioni di edifici a basso consumo energetico - Le recenti esperienze europeee ed il progetto GREYNERGY
No full textBiodiversity loss and turnover in alternative states in the Mediterranean Sea: a case study on meiofauna
No full textIn the Mediterranean Sea hard-bottom macroalgal meadows may switch to alternative and less-productive barrens grounds, as a result of sea urchins overgrazing. Meiofauna (and especially nematodes) represent key components of benthic ecosystems, are highly-diversified, sensitive to environmental change and anthropogenic impacts, but, so-far, have been neglected in studies on regime shifts. We report here that sedimentary organic matter contents, meiofaunal taxa richness and community composition, nematode α- and β-biodiversity vary significantly between alternative macroalgal and barren states. The observed differences are consistent in six areas spread across the Mediterranean Sea, irrespective of barren extent. Our results suggest also that the low biodiversity levels in barren states are the result of habitat loss/fragmentation, which is associated also with a lower availability of trophic resources. Furthermore, differences in meiofaunal and nematode abundance, biomass and diversity between macroalgal meadow and barren states persist when the latter is not fully formed, or consists of patches interspersed in macroalgal meadows. Since barren grounds are expanding rapidly along the Mediterranean Sea and meiofauna are a key trophic component in marine ecosystems, we suggest that the extension and persistence of barrens at the expenses of macroalgal meadows could also affect resilience of higher trophic level
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
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