196,544 research outputs found
Data for: Water and sediment temperature dynamics in shallow tidal environments: the role of the heat flux at the soil-water interface.
No full textWater and sediment temperature data collected in a shallow tidal flat located in the Northern part of the Venice lagoon (see figure 1 in the manuscript).The bottom elevation at the measuring station is 0:65 m below mean sea level, and the local tidal range is about 0.80 m during a spring tide and 0.50 m during a neap tide.5 sensors (ControlByWeb, Xytronix Inc. Utah, USA) were deployed in the sediment (depth of 5, 25, 50, 100, and 150 cm below the sediment surface) and 4 sensors in the water column (10, 40, 70, 100 cm above the sediment surface). Data were collected with a 5 minutes resolution
Chlamydomonas reinhardtii cellular compartments and their contribution to intracellular calcium signalling
No full textCalcium (Ca2+)-dependent signalling plays a well-characterized role in the response to different environmental stimuli, in both plant and animal cells. In the model organism for green algae, Chlamydomonas reinhardtii, Ca2+ signals were reported to have a crucial role in different physiological processes, such as stress responses, photosynthesis, and flagella functions. Recent reports identified the underlying components of the Ca2+ signalling machinery at the level of specific subcellular compartments and reported in vivo imaging of cytosolic Ca2+ concentration in response to environmental stimuli. The characterization of these Ca2+-related mechanisms and proteins in C. reinhardtii is providing knowledge on how microalgae can perceive and respond to environmental stimuli, but also on how this Ca2+ signalling machinery has evolved. Here, we review current knowledge on the cellular mechanisms underlying the generation, shaping, and decoding of Ca2+ signals in C. reinhardtii, providing an overview of the known and possible molecular players involved in the Ca2+ signalling of its different subcellular compartments. The advanced toolkits recently developed to measure time-resolved Ca2+ signalling in living C. reinhardtii cells are also discussed, suggesting how they can improve the study of the role of Ca2+ signals in the cellular response of microalgae to environmental stimuli
A proposito di Public History
No full textIl dibattito sull'uso pubblico della storia si è di recente arricchito dell'apporto della Public history. A fronte di una generalizzata smemoratezza delle giovani generazioni l'uso pubblico della storia ha esteso le conoscenze del passato: non solo libri e manuali costituiscono la fonte di informazione dei secoli passati ma anche i musei, le mostre, la diaristica privata, i cinegiornali, etc. Insomma una serie di "frammenti" fino a ora dimenticati e che costituiscono nuove fonti per la conoscenza del passat
I colori della politica. Passioni, emozioni e rappresentazioni della politica nell’età contemporanea
No full textA proposito di Public History
No full textIl dibattito sull'uso pubblico della storia si è di recente arricchito dell'apporto della Public history. A fronte di una generalizzata smemoratezza delle giovani generazioni l'uso pubblico della storia ha esteso le conoscenze del passato: non solo libri e manuali costituiscono la fonte di informazione dei secoli passati ma anche i musei, le mostre, la diaristica privata, i cinegiornali, etc. Insomma una serie di "frammenti" fino a ora dimenticati e che costituiscono nuove fonti per la conoscenza del passat
Storia di San Marino. Medioevo, Età moderna e contemporanea, Novecento e tempo presente
No full textAbiotic Stress-Induced Chloroplast and Cytosolic Ca2+ Dynamics in the Green Alga Chlamydomonas reinhardtii
No full textCalcium (Ca2+)-dependent signalling plays a well-characterised role in the perception and response mechanisms to environmental stimuli in plant cells. In the context of a constantly changing environment, it is fundamental to understand how crop yield and microalgal biomass productivity are affected by external factors. Ca2+ signalling is known to be important in different physiological processes in microalgae but many of these signal transduction pathways still need to be characterised. Here, compartment-specific Ca2+ dynamics were monitored in Chlamydomonas reinhardtii cells in response to environmental stressors, such as nutrient availability, osmotic stress, temperature fluctuations and carbon sensing. An in vivo single-cell imaging approach was adopted to directly visualise changes of Ca2+ concentrations at the level of specific subcellular compartments, using C. reinhardtii lines expressing a genetically encoded ratiometric Ca2+ indicator. Hyper-osmotic shock caused cytosolic and chloroplast Ca2+ elevations, whereas high temperature and inorganic carbon availability primarily induced Ca2+ transients in the chloroplast. In contrast, hypo-osmotic stress only induced Ca2+ elevations in the cytosol. The results herein reported show that in Chlamydomonas cells compartment-specific Ca2+ transients are closely related to specific external environmental stimuli, providing useful guidance for studying signal transduction mechanisms exploited by microalgae to respond to specific natural conditions
Water and Sediment Temperature Dynamics in Shallow Tidal Environments
No full textThe purpose of the present study is to investigate the water and sediment temperature dynamics in shallow coastal environments. Indeed, water and sediment temperature dynamics are a first order control of many physical and biological processes in aquatic ecosystem, driving the short and long term evolution of the ecosystem.
Given the scarcity of studies and data from the literature that investigate in particular the heat fluxes at the sediment-water interface (SWI), we conceived and performed an ad hoc, one-year-long field campaign was performed in the Venice lagoon to collect water and sediment temperature data. The collected data show that, in our study site, temperature is uniform within the water column, and enabled us to estimate the net heat flux at the sediment-water interface. Based on these results we developed a "point" model for describing the temperature dynamics of the sediment-water continuum in shallow tidal environments. Modeling the flux at the SWI as the sum of a conductive component and of the solar radiation reaching the bottom, we found the latter being negligible. Our analysis further revealed that, in general, horizontal advection driven by tidal currents is an important process also at our study site despite we placed it quite close to a divide. For applying the "point" model we therefore selected, in our data set, only periods when advection is negligible, that correspond to periods characterized by neap tide and small temperature difference between sea and lagoon. The results we obtained following our numerical approach are quite satisfactory showing the capability of the model of reproducing, in the selected conditions, the temperature dynamics both in the water column and within the sediments. Both the analysis of the data and model results show that the heat exchange between water and sediment is crucial for describing sediment temperature but plays a minor role on the water temperature. This observation suggests that, as a first approximation, the water temperature dynamics can be modeled neglecting the heat exchange between water and sediments.
Using the developed numerical model we further investigated the effect of different turbidity conditions of the water column on the water and sediment temperature and on the photosynthetic capacity of the microphytobenthos (MPB), i.e. communities of microalgae commonly present in coastal environments and colonizing the uppermost layer of bed sediments. We found that the water temperature dynamics is poorly affected by the different conditions investigated, while the sediment temperature variation is significant, especially for very shallow water depth (i.e. ≤0.5 m). Considering the average annual budget, the photosynthetic rate of the MPB is found to be better promoted by clear water conditions, being the light availability the major limiting factor for the photosynthetic process. These results suggest the possibility of investigating a positive feedback between water column turbidity and the MPB proliferation, driven by its photosynthetic capacity. In fact, the abundance of MPB provides a bio-stabilization of the sediment bottom, creating a biofilm that limits sediment resuspension and thus reduces the water column turbidity
Tides, Topography, and Seagrass Cover Controls on the Spatial Distribution of Pinna nobilis on a Coastal Lagoon Tidal Flat
No full textIn the last two decades Pinna nobilis, the largest bivalve mollusk endemic to the Mediterranean Sea, has recolonized the tidal flats of some coastal lagoons along the Italian Adriatic coast. In this study, we investigate the influence of tides on the spatial distribution and density of a P. nobilis population developing on a tidal flat of the Venice lagoon (NE Italy) by exploiting remote sensing technologies. Our results show that there is a threshold topographic elevation (about 0.5 m below mean sea level for the studied tidal flat) above which the number and duration of emersions become limiting factors of P. nobilis abundance. Above this elevation, the population density decreases sharply. Densely populated areas tend to occur in tidal flat depressions, where the duration and frequency of emersions are low. We find, however, that the population density has large spatial variability in response to other factors, such as the seagrass percentage cover. The density of the shells increases with increasing seagrass percentage cover, and the dense P. nobilis population (0.8–2.68 N/m2) grows within the Cymodocea nodosa meadow that has a high seagrass percentage cover (>85%). However, within the seagrass meadow with the highest percentage cover, the bivalve preferentially colonizes the portion closest to the main channel, a possible source of nutrients. The shift to C. nodosa—dominated meadows in the Venice lagoon occurred during the last two decades has probably facilitated the observed colonization by P. nobilis. Our findings provide management information for protection and/or restoration of P. nobilis in coastal lagoons
Water and sediment temperature dynamics in shallow tidal environments: the role of the heat flux at the sediment-water interface
No full textIn the present study, we investigate the energy flux at the sediment-water interface and the relevance of the heat exchanged between water and sediment for the water temperature dynamics in shallow coastal environments. Water and sediment temperature data collected in the Venice lagoon show that, in shallow, temperate lagoons, temperature is uniform within the water column, and enabled us to estimate the net heat flux at the sediment-water interface. We modeled this flux as the sum of a conductive component and of the solar radiation reaching the bottom, finding the latter being negligible. We developed a “point” model to describe the temperature dynamics of the sediment-water continuum driven by vertical energy transfer. We applied the model considering conditions characterized by negligible advection, obtaining satisfactory results. We found that the heat exchange between water and sediment is crucial for describing sediment temperature but plays a minor role on the water temperature
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