132 research outputs found

    Distribution and biology of lightiella magdalenina (crustacea, cephalocarida)

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    Lightiella magdalenina is the more recently cephalocarid species described (La Maddalena Archipelago, Sardinia). This first important finding in the Mediterranean sea fills a gap in the distribution of the genus and of the entire class. The aim of the present study is to report some information about distribution and biology of this cephalocarid species. L. magdalenina, like most cephalocarid species, shows a pronounced anamorphic mode of development with a gradual and sequential addition of segment and limbs throughout more of 17 stages of development. It is currently known from a single locality where 55 specimens have been found during more than nine years of sampling. The Type locality is characterised by muddy sand bottom, very rich in organic matter with leaf fragments of Posidonia oceanica; grain size analysis, has underlined that sand is a very fine sand with an organic component of 95%. Zoobenthos was composed of 11 different taxa; Cletopsyllidae and Normanellidae Copepoda are unknown for Italy. A new species of family Cletopsyllidae, Isocletopsyllus sp. nov. has been identified. Up to present, only one species Hutchinsoniella macracantha, have been studied at molecular level. We report the partial sequences of two mitochondrial genes of relevant importance for phylogenetic analysis (cytochrome c oxidase I and cytochrome b) from Lightiella magdalenina. A reduced median network analysis clarified the genetic relationships between the two cephalocarid species

    Spermatogenesis and sperm structure in the black-striped pipefish <i>Syngnathus abaster</i> (Teleostei, Syngnathidae) = Spermatogenesi e struttura degli spermatozoi in <i>Syngnathus abaster</i> (Teleostei, Synghathidae)

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    The gonads of adult males of the black-striped pipejish Syngnathus abaster were observed during the reproductive season to describe mature sperm both quantitativel/y and qualitatively. The results show that: a) the sperms number is always very low and, does not vary significantly during the reproductive season; b) all mature sperms observed may be assigned to the introsperm-like type. These data suggest that the unique and functional sperm of Syngnathids pertain to the introsperm type typical of internally fertilizing teleostean bony fishes

    An algorithm for PWL approximations of nonlinear functions

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    In this report we provide some technical details for some of the results appeared in [Alessio et al.(2005)]. In the first section we provide the proof of continuity of the PPWA function computed with the ”squaring the circle” algorithm stated in ACC 06. Then, we analyze the complexity of the previous algorithm, in terms of the desired level of accuracy in the approximation of the PPWA function

    Modelo de distribución espacial y estructura poblacional del erizo de mar Paracentrotus lividus (Echinodermata: Echinoidea) en la pesquería costera de Cerdeña occidental (Mediterráneo occidental): aplicación de un enfoque geoestadístico

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    The identification of appropriate spatial distribution patterns for the observation, analysis and management of stocks with a persistent spatial structure, such as sea urchins, is a key issue in fish ecology and fisheries research. This paper describes the development and application of a geostatistical approach for determining the spatial distribution and resilience of the population of the sea urchin Paracentrotus lividus in a fishing ground of western Sardinia (western Mediterranean). A framework combining field data collection, experimental modelling and mapping was used to identify the best-fit semivariogram, taking pre-fishing and post-fishing times into consideration. Variographic analyses indicate autocorrelation of density at small distances, while the isotropic Gaussian and spherical models are suitable for describing the spatial structure of sea urchin populations. The point kriging technique highlights a generally patchy population distribution that tends to disappear during the fishing season. Kriging maps are also useful for calculating predictable stock abundances, and thus mortality rates, by class diameters within six months of fishing. We conclude that the framework proposed is adequate for biomass estimation and assessment of sea urchin resources. This framework can therefore be regarded as a useful tool for encouraging a science-based management of this fishery.La identificación de modelos de distribución espacial apropiados para la observación, análisis y ordenación de los stocks con estructura espacial constante, como los erizos de mar, son temas clave en la ecología de los peces e investigación de pesquerías. El presente trabajo describe el desarrollo y aplicación de un enfoque geoespacial para determinar la distribución espacial y resistencia de la población del erizo de mar (Paracentrotus lividus) en un área pesquera al oeste de Cerdeña (Mediterráneo occidental). Se utilizó un marco que combina la recolección de datos de campo, modelos experimentales y mapas, para identificar el mejor ajuste en el semivariograma, teniendo en cuenta tiempos antes y después de la pesca. Los análisis variográficos indican una autocorrelación para la densidad a pequeñas distancias, mientras que los modelos isotrópicos Gaussianos y esféricos son apropiados para describir la estructura espacial de las poblaciones del erizo de mar. La técnica del kriging puntual destaca una distribución desigual de la población que tiende a desaparecer durante la temporada de pesca. Los mapas que utilizan kriging son también útiles para calcular una abundancia fiable del stock, y por lo tanto tasas de mortalidad por clases de diámetro en un período de seis meses de pesca. Concluimos que el marco propuesto es adecuado para la estimación de la biomasa y ordenación del recurso de erizo de mar. Por lo tanto, puede considerarse como una herramienta útil para apoyar una ordenación científica de esta pesquería

    Modelo de distribución espacial y estructura poblacional del erizo de mar Paracentrotus lividus (Echinodermata: Echinoidea) en la pesquería costera de Cerdeña occidental (Mediterráneo occidental): aplicación de un enfoque geoestadístico

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    The identification of appropriate spatial distribution patterns for the observation, analysis and management of stocks with a persistent spatial structure, such as sea urchins, is a key issue in fish ecology and fisheries research. This paper describes the development and application of a geostatistical approach for determining the spatial distribution and resilience of the population of the sea urchin Paracentrotus lividus in a fishing ground of western Sardinia (western Mediterranean). A framework combining field data collection, experimental modelling and mapping was used to identify the best-fit semivariogram, taking pre-fishing and post-fishing times into consideration. Variographic analyses indicate autocorrelation of density at small distances, while the isotropic Gaussian and spherical models are suitable for describing the spatial structure of sea urchin populations. The point kriging technique highlights a generally patchy population distribution that tends to disappear during the fishing season. Kriging maps are also useful for calculating predictable stock abundances, and thus mortality rates, by class diameters within six months of fishing. We conclude that the framework proposed is adequate for biomass estimation and assessment of sea urchin resources. This framework can therefore be regarded as a useful tool for encouraging a science-based management of this fishery.La identificación de modelos de distribución espacial apropiados para la observación, análisis y ordenación de los stocks con estructura espacial constante, como los erizos de mar, son temas clave en la ecología de los peces e investigación de pesquerías. El presente trabajo describe el desarrollo y aplicación de un enfoque geoespacial para determinar la distribución espacial y resistencia de la población del erizo de mar (Paracentrotus lividus) en un área pesquera al oeste de Cerdeña (Mediterráneo occidental). Se utilizó un marco que combina la recolección de datos de campo, modelos experimentales y mapas, para identificar el mejor ajuste en el semivariograma, teniendo en cuenta tiempos antes y después de la pesca. Los análisis variográficos indican una autocorrelación para la densidad a pequeñas distancias, mientras que los modelos isotrópicos Gaussianos y esféricos son apropiados para describir la estructura espacial de las poblaciones del erizo de mar. La técnica del kriging puntual destaca una distribución desigual de la población que tiende a desaparecer durante la temporada de pesca. Los mapas que utilizan kriging son también útiles para calcular una abundancia fiable del stock, y por lo tanto tasas de mortalidad por clases de diámetro en un período de seis meses de pesca. Concluimos que el marco propuesto es adecuado para la estimación de la biomasa y ordenación del recurso de erizo de mar. Por lo tanto, puede considerarse como una herramienta útil para apoyar una ordenación científica de esta pesquería

    Incorporation of probiotic bacteria (Lactobacillus acidophilus and Bifidobacterium ssp.) in Argentinean ovine cheese

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    The market of cheeses from ewe’s milk has been growing steadily in Argentina. The nutritional benefits of these products can be enhanced by adding probiotic cultures. In the present study, the survival of a mix of probiotic microorganisms (Lactobacillus acidophilus La-5 and Bifidobacterium animalis ssp. lactis Bb12) in a semi-hard ovine cheese, manufactured with a technology previously developed in our institute was evaluated. Besides, the effect of its incorporation on the chemical composition and ripening parameters of cheeses, including the fatty acid composition and CLA production, was investigated. Experimental cheeses made with Bb12 and La-5 retained counts of the probiotic strains at the required therapeutic level (107 CFU g−1 ). No significant differences were detected between experimental and control cheeses with respect to the different parameters evaluated: gross composition, nitrogen fractions, lipolysis, fatty acids profiles of cheese fat including CLA, and volatile fraction. Results demonstrated that the ovine cheese matrix seems to be suitable for delivery of probiotic microorganisms.Fil: Perotti, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; ArgentinaFil: Wolf, Irma Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; ArgentinaFil: Addis, Margherita. AGRIS Sardegna. Dipartamento per la ricerca nelle produzioni animali (DIRPA), Sardegna; ItaliaFil: Comunian, Roberta. AGRIS Sardegna. Dipartamento per la ricerca nelle produzioni animali (DIRPA), Sardegna; ItaliaFil: Paba, Antonio. AGRIS Sardegna. Dipartamento per la ricerca nelle produzioni animali (DIRPA), Sardegna; ItaliaFil: Meinardi, Carlos Alberto. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentin

    Reproductive system of <i>Lightiella magdalenina</i> (Crustacea, Cephalocarida) = Apparato riproduttore in <i>Lightiella magdalenina</i> (Crustacea, Chefalocarida)

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    The aim of this study was to describe the morphology of the reproductive system of Lightiella magdalenina the only cefalocarid species known from Europe. Two adult specimens and one larval stage of L. magdalenina were analysed with light microscope and findings compared with available data from H. macracantha

    Optimal Probabilistic Energy-Aware Routing for Duty-Cycled Wireless Sensor Networks

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    International audienceNetwork lifetime is still the key issue when we deploy wireless sensor networks and IoT solutions in real-world applications. Current WSN research trends include duty-cycling at MAC layer and energy efficient routing at network layer, among others. In this study we propose an Optimal Probabilistic Energy-Aware Routing Protocol (OPEAR) for duty-cycled WSNs which aims at maximizing the network lifetime by keeping low energy consumption and balancing network traffic between nodes. Our experimental campaign reveals that our OPEAR protocol outperforms the popular Energy Aware Routing Protocol (EAR) from the literature, proving to be more effective in extending the network lifetime

    The liposoluble proteome of Mycoplasma agalactiae: an insight into the minimal protein complement of a bacterial membrane

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    <p>Abstract</p> <p>Background</p> <p>Mycoplasmas are the simplest bacteria capable of autonomous replication. Their evolution proceeded from gram-positive bacteria, with the loss of many biosynthetic pathways and of the cell wall. In this work, the liposoluble protein complement of <it>Mycoplasma agalactiae</it>, a minimal bacterial pathogen causing mastitis, polyarthritis, keratoconjunctivitis, and abortion in small ruminants, was subjected to systematic characterization in order to gain insights into its membrane proteome composition.</p> <p>Results</p> <p>The selective enrichment for <it>M. agalactiae </it>PG2<sup>T </sup>liposoluble proteins was accomplished by means of Triton X-114 fractionation. Liposoluble proteins were subjected to 2-D PAGE-MS, leading to the identification of 40 unique proteins and to the generation of a reference 2D map of the <it>M. agalactiae </it>liposoluble proteome. Liposoluble proteins from the type strain PG2 and two field isolates were then compared by means of 2D DIGE, revealing reproducible differences in protein expression among isolates. An in-depth analysis was then performed by GeLC-MS/MS in order to achieve a higher coverage of the liposoluble proteome. Using this approach, a total of 194 unique proteins were identified, corresponding to 26% of all <it>M. agalactiae </it>PG2<sup>T </sup>genes. A gene ontology analysis and classification for localization and function was also carried out on all protein identifications. Interestingly, the 11.5% of expressed membrane proteins derived from putative horizontal gene transfer events.</p> <p>Conclusions</p> <p>This study led to the in-depth systematic characterization of the <it>M. agalactiae </it>liposoluble protein component, providing useful insights into its membrane organization.</p

    <i>Mycoplasma agalactiae</i> MAG_5040 is a Mg<sup>2+</sup>-dependent, sugar-nonspecific SNase recognised by the host humoral response during natural infection

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    In this study the enzymatic activity of Mycoplasma agalactiae MAG_5040, a magnesium-dependent nuclease homologue to the staphylococcal SNase was characterized and its antigenicity during natural infections was established. A UGA corrected version of MAG_5040, lacking the region encoding the signal peptide, was expressed in Escherichia coli as a GST fusion protein. Recombinant GST-MAG_5040 exhibits nuclease activity similar to typical sugar-nonspecific endo- and exonucleases, with DNA as the preferred substrate and optimal activity in the presence of 20 mM MgCl2 at temperatures ranging from 37 to 45uC. According to in silico analyses, the position of the gene encoding MAG_5040 is consistently located upstream an ABC transporter, in most sequenced mycoplasmas belonging to the Mycoplasma hominis group. In M. agalactiae, MAG_5040 is transcribed in a polycistronic RNA together with the ABC transporter components and with MAG_5030, which is predicted to be a sugar solute binding protein by 3D modeling and homology search. In a natural model of sheep and goats infection, anti-MAG_5040 antibodies were detected up to 9 months post infection. Taking into account its enzymatic activity, MAG_5040 could play a key role in Mycoplasma agalactiae survival into the host, contributing to host pathogenicity. The identification of MAG_5040 opens new perspectives for the development of suitable tools for the control of contagious agalactia in small ruminants
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