154 research outputs found

    First report of chimerism in the Mediterranean red coral (Corallium rubrum)

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    The phenomenon of chimerism in the Mediterranean red coral (Corallium rubrum) is reported and quantified in semi-natural conditions. 1688 larvae were maintained in closed circuit in presence of a suitable settlement surface (marble tiles). Post settlement survival and chimera formation were monitored for 1 year. According to our observation, when polyps settle at close contact, a high frequency of chimerism is observed (32%). After 1 year, only 33% of chimeric individuals survived but they are 40% bigger than not chimeric ones, suggesting that chimerism could confer a competitive advantage linked to increased growth rate

    Population dynamics and conservation biology of over-exploited Mediterranean red coral.

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    Abstract The main goal of ecologists is nowadays to foster habitat and species conservation. Life-history tables and Leslie-Lewis transition matrices of population growth can be powerful tools suitable for the study of age-structured over harvested and/or endangered species dynamics. Red coral (Corallium rubrum L 1758) is a modular anthozoan endemic to the Mediterranean Sea. This slow growing, long lived species has been harvested since ancient times. In the last decades harvesting pressure increased and the overall Mediterranean yield reduced by 2 3 . Moreover, mass mortality (putatively-linked to global warming) recently affected some coastal populations of this species. Red coral populations are discrete genetic units, gonochoric, composed by several overlapping generations and provided of a discrete (annual) reproduction. A population of this precious octocoral was studied in detail and its static life table was compiled. In order to simulate the trends overtime of the population under different environmental conditions and fishing pressures, a discrete, non-linear model, based on Leslie-Lewis transition matrix, was applied to the demographic data. In this model a bell-shaped curve, based on experimental data, representing the dependence of recruitment on adult colonies density was included. On these bases the stability of the population under different density, reproduction and mortality figures was analysed and simulations of the population trends overtime were set out. Some simulations were also carried out applying to the studied population the mortality values measured during the anomalous mass mortality event which really affected some red coral populations in 1999. The population under study showed high stability and a strong resilience capability, surviving to a 61% reduction of density, to a 27.7% reduction of reproduction rate and to an unselective harvesting affecting 95% of the reproductive colonies.

    A Movement-Tremors Recorder for Patients of Neurodegenerative Diseases

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    Neurodegenerative diseases such as Alzheimer, Parkinson, motor neuron, and Chorea affect millions of people today. Their effect on the central nervous system causes the loss of brain functions as well as motor disturbances and sometimes cognitive deficits. In such a scenario, the monitoring and evaluation of early symptoms are mandatory for the improvement of the patient's quality of life. Here, the authors describe the development, the laboratory calibration, and the "in-field validation" under the medical supervision of a movement tremors recorder for subjects affected by neurodegenerative diseases. The developed device is based on an array of four accelerometers connected to an embedded development board. This system is able to monitor tremor/movement, accidental falls, and, moreover, it can track the Alzheimer subjects' geographical position. A remote supervisor can collect data from the system through Bluetooth, Wi-Fi, or GSM connections. A data compression algorithm was developed directly on board in order to increase the efficiency of data transmission and reduce power consumptions

    Thread-like tentacles in the Mediterranean corals Paramuricea clavata and Corallium rubrum

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    The occurrence of modified tentacles (i.e. thread-like tentacles) in the Mediterranean octocorals Paramuricea clavata and Corallium rubrum is reported. Colonies of four species of Mediterranean gorgonians were maintained in aquarium conditions for more than 5 months. The development of thread-like tentacles has been observed only in two of the four species. The presence of modified tentacles in other cnidarians has been usually associated with defensive/aggressive behavior. Our observations showed that thread-like tentacles in P. clavata and C. rubrum can also be used for feeding

    Limited genetic connectivity between gorgonian morphotypes along a depth gradient

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    Gorgonian species show a high morphological variability in relation to the environment in which they live. In coastal areas, parameters such as temperature, light, currents, and food availability vary significantly with depth, potentially affecting morphology of the colonies and the structure of the populations, as well as their connectivity patterns. In tropical seas, the existence of con- nectivity between shallow and deep populations supported the hypothesis that the deep coral reefs could potentially act as (reproductive) refugia fostering re-colonization of shallow areas after mortality events. Moreover, this hypothesis is not so clear accepted in temperate seas. Eunicella singularis is one of the most common gorgonian species in Northwestern Mediterranean Sea, playing an important role as ecosystem engineer by providing biomass and com- plexity to the coralligenous habitats. It has a wide bathymetric distribution ranging from about 10 m to 100 m. Two depth-related morphotypes have been identified, differing in colony mor- phology, sclerite size and shape, and occurrence of symbiotic algae, but not in mitochondrial DNA haplotypes. In the present study the genetic structure of E. singularis populations along a horizontal and bathymetric gradient was assessed using microsatellites and ITS1 sequences. Restricted gene flow was found at 30-40 m depth between the two Eunicella morphotypes. Conversely, no genetic structuring has been found among shallow water populations within a spatial scale of ten kilometers. The break in gene flow between shallow and deep populations contributes to explain the morphological variability observed at different depths. Moreover, the limited vertical connectivity hinted that the refugia hypothesis does not apply to E. singularis. Re-colonization of shallow water populations, occasionally affected by mass mortality events, should then be mainly fueled by larvae from other shallow water populations

    Pile-Ups Formation in AFM-Based Nanolithography: Morpho-Mechanical Characterization and Removal Strategies

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    In recent decades, great efforts have been made to develop innovative, effective, and accurate nanofabrication techniques stimulated by the growing demand for nanostructures. Nowadays, mechanical tip-based emerged as the most promising nanolithography technique, allowing the pattern of nanostructures with a sub-nanometer resolution, high reproducibility, and accuracy. Unfortunately, these nanostructures result in contoured pile-ups that could limit their use and future integration into high-tech devices. The removal of pile-ups is still an open challenge. In this perspective, two different AFM-based approaches, i.e., Force Modulation Mode imaging and force-distance curve analysis, were used to characterize the structure of pile-ups at the edges of nanogrooves patterned on PMMA substrate by means of Pulse-Atomic Force Lithography. Our experimental results showed that the material in pile-ups was less stiff than the pristine polymer. Based on this evidence, we have developed an effective strategy to easily remove pile-ups, preserving the shape and the morphology of nanostructures

    Organ Stiffness in the Work-Up of Myelofibrosis and Philadelphia-Negative Chronic Myeloproliferative Neoplasms

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    To define the role of spleen stiffness (SS) and liver stiffness (LS) in myelofibrosis and other Philadelphia (Ph)-negative myeloproliferative neoplasms (MPNs), we studied, by ultrasonography (US) and elastography (ES), 70 consecutive patients with myelofibrosis (MF) (no.43), essential thrombocythemia (ET) (no.10), and polycythemia vera (PV) (no.17). Overall, the median SS was not different between patients with MF and PV (p = 0.9); however, both MF and PV groups had significantly higher SS than the ET group (p = 0.011 and p = 0.035, respectively) and healthy controls (p < 0.0001 and p = 0.002, respectively). In patients with MF, SS values above 40 kPa were significantly associated with worse progression-free survival (PFS) (p = 0.012; HR = 3.2). SS also correlated with the extension of bone marrow fibrosis (BMF) (p < 0.0001). SS was higher in advanced fibrotic stages MF-2, MF-3 (W.H.O. criteria) than in pre-fibrotic/early fibrotic stages (MF-0, MF-1) (p < 0.0001) and PFS was significantly different in the two cohorts, with values of 63% and 85%, respectively (p = 0.038; HR = 2.61). LS significantly differed between the patient cohort with MF and healthy controls (p = 0.001), but not between the patient cohorts with ET and PV and healthy controls (p = 0.999 and p = 0.101, respectively). We can conclude that organ stiffness adds valuable information to the clinical work-up of MPNs and could be employed to define patients at a higher risk of progression

    Early stages of development in Mediterranean red coral (Corallium rubrum): The key role of sclerites

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    Corals are ecosystem engineers whose tree-like structures give three-dimensional complexity to the habitat. Their population dynamics are affected by recruitment and juvenile survival. Therefore, several defense strategies, such as the formation of hard skeletons and/or spicules, have evolved to protect these vulnerable stages. The family Coralliidae, to which “precious corals” belong, represent an exception in the order Scleralcyonacea, as they form hard CaCO3 skeletons and small CaCO3 structures, the sclerites. The skeletogenesis of Corallium species is relatively well documented in adult colonies but remains poorly known in the early stages of the development of new colonies. To shed light on the timing of Corallium rubrum’s early skeleton formation and the role of sclerites, we focused on the first 4-years of life, applying different techniques, from scanning electron microscopy to synchrotron tomography and laser ablation inductively coupled plasma-mass spectrometry. Our results show that: 1) the first visible sclerites in the primary polyp appear at least 12 days after larval settlement, which is associated with a high CaCO3 production rate (4.5 ± 2.3 ÎŒg of CaCO3 per day). Furthermore, growth rings are visible in the sclerites, showing that fully matured sclerites grow fast, probably in 3 to 4 days. 2) Sclerites are the only biomineral product in the first year of life of C. rubrum’s colonies. 3) The evidence of a consolidated axial skeleton, intended as the inner part of the skeleton characteristic of the adult red coral (the medullary zone, MZ), is recorded for the first time in 2-year-old colonies. 4) The annular zone (AZ) around the medullary zone starts forming not before four years after settlement. Thus, primary polyp builds a deformable armor made of only sclerites during the first year. This shelter provides mechanical protection from abrasion and predation to early settled colonies. After two years, settlers are firmly and mineralogically attached to the substratum, which makes them less vulnerable to predation than younger recruits that are not anchored by the skeleton

    Anthropogenic effects on reproductive effort and allocation of energy reserves in the Mediterranean octocoral Paramuricea clavata

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    12 pages, 6 figures, 1 table, supplementary material in http://www.int-res.com/articles/suppl/m449p161_supp/In order to better understand the sources, patterns and consequences of anthropogenic effects on populations of the Mediterranean gorgonian Paramuricea clavata, we examined the proportion of injured colonies among populations exposed to a combination of anthropogenic disturbances (recreational cast fishing, commercial lobster pots, gill nets and SCUBA diving), as well as the physiological response of injured corals. Between 10 and 33% of the colonies in unprotected populations were partially colonized by epibionts, most likely following tissue injury, whereas only 4 to 10% of the populations in a marine protected area were affected. Populations that were simultaneously exposed to fishing as well as intensive SCUBA diving showed the highest proportion of colonization. Colonies with approximately 30 to 35% of epibiont coverage showed significantly lower numbers of gonads per polyp. Similarly, concentrations of lipids were lower in females with epibionts, thus indicating allocation of resources into recovery of injured tissue instead of reproduction. Furthermore, whereas unaffected colonies showed a uniform distribution of carbohydrates and proteins through apical branches to more central ones, colonies with epibionts had significantly lower protein concentrations in branches that are positioned 3 branching order levels closer to the stem. The results thus indicate a preference of apical growth in recovering colonies, via a different distribution of food within the colony. Reproductive success in surface-brooding corals growing on walls and overhangs might also be reduced by SCUBA bubbles from divers passing below, as bubbles efficiently remove eggs brooded on colony branches. © 2012 Inter-ResearchThis study was funded by the Spanish Ministry of Science and Innovation, project BENTOLARV (CTM2009-10007). S.R. is a Ramón y Cajal fellow (RyC-2007-01327). L.B. is supported through the EU Marie Curie Program (IEF 221072), and N.V. is supported through a scholarship by the Generalitat de Catalunya (FI2010)Peer Reviewe
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