414 research outputs found

    The nematode assemblage of a coastal lagoon (Lake Varano, southern Italy): ecology and biodiversity patterns

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    Este estudio tiene como objetivo analizar cuál y en qué medida los parámetros ambientales influyen en la diversidad taxonómica y funcional de los nematodos y clasificar por primera vez el Estado de la Calidad Ecológica (EQS) de un ambiente de transición como la laguna de Varano (Italia meridional). La composición y el nivel de divesidad taxonómica son comparables con los reportados en todo el mundo para TEs. El análisis de componentes principales reveló que los factores que controlan la composición y las características biológicas de las comunidades son el tamaño del gránulo, la materia orgánica (MO), el índice de aportes contaminados (PLI) y sólo secundariamente la salinidad. Molgolaimus allgeni, Terschellingia longicaudata y Leptolaimus luridus aumentan en número en relación con el limo, la MO y el PLI, mientras Axonolaimus caudostriatus, Odontophora wieseri, Paramonhystera pelúcida y Paracanthonchus longicaudatus muestran valores más altos en relación con el potencial redox y el porcentaje de arena. La salinidad tuvo una influencia secundaria y en particular sobre las especies Calomicrolaimus honestus, Daptonema normandicum, Thalassomonhystera parva and Sabatieria pulchra. Con respecto a las caracteristicas funcionales, los grupos tróficos parecen estar relacionados, principalmente, con el tipo de sedimento, lo que a su vez influye en la naturaleza de los alimentos disponibles. El índice de madurez, así como las clases c-p, no siempre permite una clara interpretación de la interacción de factores naturales y antropogénicos, sin embargo, la mayor influencia de los canales San Antonino y San Francesco fue revelada por la comunidad de nematodos. De acuerdo a las clases de Calidad Ecológica (EcoQ) corrientes el Estado de Calidad Ecológica de la laguna de Varano varía entre bueno y pobre

    Meio- and macrofauna in the marine area of the Monte St. Bartolo Natural Park (Central Adriatic Sea, Italy)

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    This paper presents an integrated investigation of benthic foraminiferal, meiofaunal and macrofaunal assemblages that was carried out in front of the marine area of the Monte St. Bartolo Regional Natural Park (Adriatic Sea, Italy). Although this area is not yet subject to conservation plans, an overall good quality status of its benthic assemblages was documented. In particular, the assemblages were somewhat diversified and generally minimally to moderately affected by anthropogenic activities. Both the foraminifera and macrofauna seemed to be primarily influenced by variations in the habitat's features, whereas significant changes in the meiofaunal assemblage were related more to trophic supply fluctuations. These data suggest the potential vulnerability of this area and highlight the importance of defining and applying an appropriate integrated zone management plan

    Habitat‐Diversity Relations between Sessile Macrobenthos and Benthic Copepods in the Rocky Shores of a Marine Protected Area

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    In rocky shore systems, sessile macrobenthic assemblages may act as “ecosystem engineers” for many smaller benthic organisms. Thus, the influence of macrobenthic coverage on the diversity and assemblage structure of the harpacticoid copepod fauna was investigated in the rocky shores of a Marine Protect Area (MPA) in the Ligurian Sea (NW, Mediterranean Sea). Two sampling sites were investigated in two seasons at three different depths on both sub‐vertical and inclined reefs. A total of 61 species of copepods mainly represented by Miraciidae, Laophontidae, Longipediidae and Thalestridae were found. The complex micro‐topography of these substrata provided a wide variety of niches for many species with different lifestyles that suggests the important role of rocky shores to ensure the functioning of coastal ecosystems. The harpacticoid assemblage structure seemed mainly influenced by season and depth. The temporal spread observed is likely one of the underlying mechanisms of niche segregation that allows many species to co‐occur in this specific environment along with a subordinate spatial segregation corresponding to the depth gradient. The results seem to support the hypothesis that the different species composition of the “ecosystem engineer” (and consequently its structure changes) are relevant in structuring the copepod assemblages. The comparison with previous data on general meiofauna underlines that higher surrogacy of the taxonomic identification could be used to study rocky shore communities, but the rich diversity that these systems host can only be understood at the lower taxonomic levels. The same holds for future evaluations of impact of environmental changes (including MPA regulations) on meiofaunal assemblages

    Integrative taxonomy of a new Redudasys species (Gastrotricha: Macrodasyida) sheds light on the invasion of fresh water habitats by macrodasyids

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    The order Macrodasyida (Gastrotricha) includes over 350 marine species, and only 3 freshwater species (Marinellina flagellata, Redudasys fornerise, R. neotemperatus). Herein we describe a new freshwater species of Macrodasyida, Redudasys brasiliensis sp. nov., from Brazil through an integrative taxonomic approach. The external morphology and internal anatomy were investigated using differential interference contrast microscopy, confocal microscopy, scanning and transmission electron microscopy. The systematization of the new taxon was inferred by nuclear (18S and 28S) and mitochondrial (COI) genes, and its intra-order relationships were assessed using data from most of available macrodasyids. Phylogenetic analyses yielded congruent trees, in which the new taxon is nested within the family Redudasyidae, but it was genetically distinct from the other species of the genus Redudasys. The new species shares the gross morphology and reproductive traits with other Redudasyidae and the presence of only 1 anterior adhesive tube per side with Redudasys neotemperatus, but it has a specific pattern of ventral ciliation and muscle organization. Results support the hypothesis that dispersion into fresh water habitats by Macrodasyida and Chaetonotida taxa occurred independently and that within Macrodasyida a single lineage invaded the freshwater environment only once. Furthermore, the Neotropical region seems to be peculiar for the evolution of the freshwater macrodasyid clade9CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIGFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP478825/2013ETC-00017-132014/23856-

    Deriving the performance indices in product-form stochastic Petri nets: Open problems and simulation

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    Stochastic Petri nets are an important formalism used for the performance evaluation of computer and communication systems as well as other fields like bioin-formatics and logistics. Despite its high flexibility and modelling power, one of the problems of quantitative analyses based on stochastic Petri nets is the state space explosion, i.e., the high cardinality reached by the state space of even a structurally small SPN. As a consequence a direct analysis of the Markovian processes underlying the models is not feasible. Product-form Petri nets are a class of stochastic Petri nets whose invariant measure can be expressed as a product of functions, each of which depends only on a marking of a single place. Nevertheless, for the effective computation of the performance indices the computation of the stationary distribution is required. In this paper we propose a classification of product-form stochastic Petri nets based on the availability of algorithms for the computation of their stationary performance indices. Moreover, in case simulation is required, we introduce two stopping criteria that exploit the product-form property of the nets

    Myelin protein zero/P0 phosphorylation and function require an adaptor protein linking it to RACK1 and PKCα

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    Point mutations in the cytoplasmic domain of myelin protein zero (P0; the major myelin protein in the peripheral nervous system) that alter a protein kinase Cα (PKCα) substrate motif (198HRSTK201) or alter serines 199 and/or 204 eliminate P0-mediated adhesion. Mutation in the PKCα substrate motif (R198S) also causes a form of inherited peripheral neuropathy (Charcot Marie Tooth disease [CMT] 1B), indicating that PKCα-mediated phosphorylation of P0 is important for myelination. We have now identified a 65-kD adaptor protein that links P0 with the receptor for activated C kinase 1 (RACK1). The interaction of p65 with P0 maps to residues 179–197 within the cytoplasmic tail of P0. Mutations or deletions that abolish p65 binding reduce P0 phosphorylation and adhesion, which can be rescued by the substitution of serines 199 and 204 with glutamic acid. A mutation in the p65-binding sequence G184R occurs in two families with CMT, and mutation of this residue results in the loss of both p65 binding and adhesion function

    Identifying the Optimal transmission range in Depth-Based Routing For UWSN

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    Routing in Underwater Wireless Sensor Networks (UWSNs) is a challenging problem because of the intrinsic characteristics of this class of wireless networks (long propagation delay, mobility of nodes, etc.) and because of the performance indices that must be taken into account, such as the network throughput, the packet delivery ratio and the energy cost. In particular, routing algorithms must grant a low energy cost in order to maximize the lifetime of the network's nodes. In this study, we focus on a popular routing protocol for UWSNs, namely the Depth-Based Routing (DBR). Specially, we study the impact of the transmission range of the nodes on the network performance indices, with particular attention to its energy efficiency. The study is based on an extensive set of simulations performed in AquaSim-NG using a library that has been developed with the aim of providing an accurate estimation of the nodes' energy consumption. The main outcome of our work is showing the relation between transmission range providing the optimal DBR energy efficiency and the density of the nodes in a UWSN
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