1,720,974 research outputs found
Effects of exposure to microplastics on the development and metamorphosis of Ciona robusta
Full text linkMicroplastics are plastic particles produced to be of small size, as sandblasting media, virgin pellet, cosmetics (Fendall and Sewell, 2009) or that originate from degradation of bigger plastic debris, as polyester fibers, polyethylene plastic bags and polystyrene particles from buoys and floats (Browne et al., 2011; Davidson, 2012; O’Brine and Thompson, 2010). An incredible amount of plastic reaches the marine environment and its ecological impacts are of particular interest. In fact, after ingestion, they may cause damage and block of feeding appendages and digestive system, can migrate from alimentary canal to other body tissues, limit the food intake and transfer pollutants in living organisms (Cole et al., 2013).
We evaluated microplastics effects on development and metamorphosis of the solitary ascidian Ciona robusta. We used microbeads with 10 μm diameter made of polystyrene, because it is highly stable with a negligible styrene migration (Cohen et al., 2002). We tested four different concentrations (0.125, 1.25, 12.5 and 25 μg/ml) and analyzed the effects on larval development and survival. Then we exposed attached larvae for five days to test the effects on metamorphosis. Juvenile survival was calculated exposing metamorphosed individuals to microplastics for eight days. We also estimated the ingestion rate as the number of particles ingested in one minute and the expulsion capability measuring the localization of particles in stomach or fecal pellets after 24 hours.
Metamorphosis was the process most affected by the microplastics. In fact, the percentage of individuals that completed metamorphosis was statistically lower in all the exposed groups, compared to control. Feeding individuals were also fed with microalgae. The co-ingestion of algae and beads probably reduced the amount of algae assimilated by the juveniles. Moreover, they might spend energy to expel microplastics thus reducing the energy available for the metamorphosis. After 8 days, juvenile survival was not affected, even if the particles persisted longer in the stomach of individuals exposed to the highest concentration, suggesting that further detrimental effects could be observed after a longer exposure
New insights on Troglophilus (Orthoptera Rhaphidophoridae) species distribution in the westernmost area of their main range (Northern Italy)
No full textThe genus TroglophilusKrauss includes species with a rather limited dispersal ability and a wide distribution range, making it a good model for biogeographic, phylogeographic and phylogenetic investigations, with growing interest in recent years. However, a crucial prerequisite for addressing biogeographic issues is the knowledge about species complete distribution range. In particu-lar, Troglophilus cavicola(Kollar) and Troglophilus neglectusKrauss are the species of the genus Troglophiluswith the widest distribution in Europe, where their main areal extends westward to Northern Italy, but their precise distribution and range limits are still uncertain. In this study, the presence of these two species, which overwinter in hypogean habitats, was investigated in caves of the westernmost area of Northern Italy (Lombardy, Provinces of Lecco and Como) where populations belonging to the genus Troglophiluswere reported. The individuals of these populations were described by previous literature as T. cavicolaor as Troglophilussp. without species determination. In this work, an in situ morphological identification of all individuals detected in the surveyed caves, and a molecular identification on 12 specimens through the COI barcoding, were performed. An effective, fast, simple, economical and easily reproducible protocol for DNA extraction was optimized for this taxon. The presence ofT. cavicolain the investigated area was confirmed and the presence of T. neglectuswas reported for the first time. These new data allowed us to hypothesize different scenarios about their dispersal route in Lombardy. Moreover, these new findings must be con-sidered to define sampling plans to elucidate the biogeography of this genus
Effects of bisphenol A on early development of the ascidian Phallusia mammillata (Chordata, Tunicata)
Full text linkBisphenol A (BPA) is an organic compound used in the manufacture of polycarbonate plastic and epoxy resins that is released into the environment from sewage treatment effluent, landfill leachate and degradation of plastic products. BPA can act both as a teratogenic substance and as an endocrine disruptor. The phylogenetic position of tunicates as sister group of vertebrates and their cosmopolitan distribution in marine ecosystems coupled with their ecology and easy manipulability make them reliable model organisms for ecotoxicology bioassays. Here we evaluated the effects of different concentration of BPA (0.1, 0.5, 1, 5, 10, and 20 μM) on ontogenetic processes sensitive to environmental pollutants in the ascidian Phallusia mammillata. To test the effects of this substance on sperm viability we fertilized eggs with sperm pre-exposed for 30 minutes to BPA. One hour post fertilization (hpf) we calculated the percentage of eggs that reached the 2-cell stage compared to control. Then we analyzed the consequences of a fertilization performed directly in BPA solutions, counting the percentage of 2 cell-stage embryos 1 hpf. To test the effects on embryogenesis, we analyzed hatched larvae developed from 2-cell embryos exposed to BPA. We evaluated the number and type of malformations under a dissection microscope and we performed immunostaining of central nervous system (CNS). Exposure of sperm to BPA did not influence fertilization rate. Coexposure of eggs and sperm at concentrations higher than 5 μM caused incomplete division of eggs, producing heart shaped embryos that did not develop further. Regarding embryogenesis, 10 μM BPA caused specific malformations at central nervous system, with an increased distance between otolith and ocellus, or an extrusion of ocellus from the sensory vesicle. Embryonic development was ignificantly altered at 20 μM concentration. 97% of the larvae presented a severely affected phenotype with short and kinked tail. Immunostainig with anti β-tubulin antibody showed an altered pattern of fibers in CNS. These results showed that the most sensitive process to BPA is the first cell division. When the 2-cell stage embryos are treated, higher concentration are required to alter the correct development of CNS. BPA confirmed its teratogenic effects on ascidians and its interference with CNS development even if the mechanism of action in this group is still to be clarified
Effects of polystyrene microplastics on early stages of two marine invertebrates with different feeding strategies
Full text linkNowadays, microplastics represent one of the main threats to marine ecosystems, being able to affect organisms at different stages of their life cycle and at different levels of the food web. Although the presence of plastic debris has been reported in different habitats and the ability to ingest it has been confirmed for different taxa, few studies have been performed to elucidate the effects on survival and development of marine animals. Thus, we explored the effects of different environmental concentrations of polystyrene microbeads on the early stages of two invertebrate species widespread in the Mediterranean shallow waters: the pelagic planktotrophic pluteus larvae of the sea urchin Paracentrotus lividus and the filter-feeding sessile juveniles of the ascidian Ciona robusta. We evaluated the effects on larvae and juvenile development and determined the efficiency of bead ingestion. The feeding stages of both species proved to be extremely efficient in ingesting microplastics. In the presence of microbeads, the metamorphosis of ascidian juveniles was slowed down and development of plutei altered. These results prompted the necessity to monitor the populations of coastal invertebrates since microplastics affect sensitive stages of life cycle and may have consequences on generation recruitment
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Effects of Bisphenol A on early development of two ascidian species
Full text linkBisphenol A(BPA) is an organic compound present in plastic products that is released into the environment after degradation. BPA is both a teratogenic substance and an endocrine disruptor. The phylogenetic position of tunicates as sister group of vertebrates and their cosmopolitan distribution in marine ecosystems make them reliable model organisms for ecotoxicology bioassays. We tested the effects of different concentration of BPA (0.1, 0.5, 1, 5, 10, and 20 μM) on sperm viability, fertilization and embryogenesis of two ascidian species, Phallusia mammillata and Ciona intestinalis. We evaluated the type and the incidence of induced malformations. Then we focused on the effects on the nervous system performing animmunostaining of central nervous system (CNS) and whole mount in situ hybridization (WISH) with neural specific markers. Exposure of sperm to BPA did not influence fertilization rate. Co-exposure of eggs and sperm to concentrations higher than 5μM caused incomplete division of zygotethat did not develop further. In P. mammillata, embryonic development was altered by 20μM BPA causing a severe phenotype with malformed sensory organs in almost all treated larvae. In C. intestinalis 20 μM BPA was lethal, while 10 μM concentration caused alteration to the sensory organs, indicating that C. intestinalis is less tolerant to BPA. Nervous system is a target of BPA action that caused an altered pattern of neural fibers. WISH with Ci-GAD and Ci-TH showed an alterationof dopaminergic and GABAergic cells after exposureto 10 μM BPA. These results showed that the most sensitive process to BPA is the first cell division. After 2-cell stage, higher concentrations are required to alter the development. BPA confirmed its teratogenic effects on ascidians and its interference with CNS development
Andamento dell'ansia, della paura e del dolore in un gruppo di pazienti ricoverati per intervento di colecistectomia semplice
No full textSono state analizzate con l'impiego di 4 test di autovalutazione alcune delle più importanti modificazioni psicologiche indotte dall'intervento chirurgico e dall'anestesia generale in 24 pazienti ricoverati per essere sottoposti a colecistectomia semplice. Le valutazioni effettuate prima e dopo l'intervento hanno mostrato come i pazienti più correttamente informati dal chirurgo prima dell'intervento anche con l'ausilio di una più appropriata terapia farmacologica, avevano una migliore reazione emotiva e di dolenzia post-operatorie
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