1,720,968 research outputs found
Histological and ultrastructural description of benign adipocytic tumors in farmed striped sea bream (Lythognathus mormyrus)
No full textCutaneous neoplasms affecting wild striped bream (Lythognathus mormyrus) have been recorded after their introduction in a marine aquaculture farm in the Adriatic Sea. The tumors were evident on 24% of the reared fish, showing single or multiple nodules, with a diameter ranging between 0.5–4.0 cm. Histologically, all the neoplastic lesions were located in the stratum spongiosum of the dermis and were surrounded by a thin capsule of connective tissue. The tumors were predomi-nantly composed of adipocytes grouped and surrounded by a thin net of fibroblasts and collagen fibers. In some lipomas a mixture of adipocytes and uniform spindle cells were also observed. Fibroblasts and collagen fibers, or spindle cells, showing few mitotic figures were mainly observed in other nodules. Three of the tumors showed bands of cells with elongated nuclei. Five neoplasms differed from the classic spindle cell lipoma due to the presence of scattered giant cells. These cells presented acidophilic abundant cytoplasm with multiple hyperchromatic nuclei showing a concentric “floret-like” arrangement. The tumors were further characterized by ultrastructural observations that allowed ruling out the presence of virus-like particles within the lesions. Histological features of the masses lead to the identification of four prevalent patterns of neoplasms: lipoma, fibrolipoma, spindle cell lipoma (SCL), and atypical spindle cell-like lipoma (ASCL). The different neoplasms could arise from the transformation of mesenchymal cells of dermal origin. To the author’s knowledge, this is the first report describing key differential histological and ultrastructural features of these neoplasms in striped sea bream
Optimization of single-strand conformation polymorphism and sequence analysis of the mitochondrial control region in Pagellus bogaraveo (Sparidae, Teleostei): Rationalized tools in fish population biology
No full textWe report the isolation and sequencing of 400-550 base pairs (bp) of the mitochondrial DNA (mtDNA) control region of eight species of Sparidae (Perciformes, Teleostei). This sequence information allowed us to design specific primers to one of these species (Pagellus bogaraveo). The new set of primers was used to test a rationalized approach to study the mtDNA nucleotide variability at the intraspecific level. The single-strand conformation polymorphism (SSCP) technique was applied to detect sequence variation in two non-overlapping fragments of the control region of 32 individuals of P. bogaraveo. To assess the sensitivity of the method, the nucleotide sequence of the analysed region was determined for all the specimens. The results showed that, for one of the two fragments, SSCP analysis was able to detect 100% of the underlying genetic variability. In sharp contrast, nucleotide variation of the second DNA fragment was completely unresolved by SSCP under different experimental conditions. This suggests that the resolution power of SSCP is crucially dependent on the nature of the fragment subjected to the analysis; therefore, a preliminary test of the sensitivity of the method should be performed on each specific DNA fragment before starting a large-scale survey. A rationalized approach, combining the SSCP technique and a simplified sequencing procedure, is proposed for studying intraspecific polymorphism at the mtDNA control region in fish
Viral Nervous Necrosis (VNN) with absence of cellular vacuolation in juveniles of sea bass (D. Labrax L.)
No full textFrom the years eighty, the viral encephalopathy-retinopathy (VER, OIE 2003), neuropathy caused by a virus belonging to genus Betanodavirus, family Nodaviridae (Ball et al., 2000), is responsible for severe losses in many species of marine farmed fish (more than 31 species distributed 16 different families) throughout the world (Munday et al., 2002). In the Mediterranean basin the VER has been quickly diffused from years ninety, affecting above all seabass (D. labrax) and, later on, shi drum (U. cirrosa ). To the contrary, spontaneous infection reports of VER in gilthead seabream (S. aurata) have been very rarely documented (Comps and Raymond 1996; Castric et al., 2001). Although the gilthead can be experimentally infected (Novoa et al., 2001; Aranguren et al., 2002), it thought that it is a resistant species, documented from the fact that, during serious VER outbreaks in seabass larvae or in other species, no gilthead larvae infection is seen. Some authors documented, through experimental infection, as this species represent rather an asymptomatic carrier of betanodavirus (Castric et al., 2001; Aranguren et al., 2002), more pathogenic for seabass. The descriptive attempt of this surveying is to document a massive mortality outbreak in 15 day-old gilthead larvae, ascribable to viral encephalopathy-retinopathy on the basis of the histopathological and immunohistochemical analyses.
Gilthead larvae, reared in tanks at density of 150ind/l and supplied to marine filtered and sterilised water (temperature 20-21°C and salinity 40‰), showed swim bladder tympanism, abdominal distension, lethargy, anorexia and alteration swim arrangement. During the acute phase of mortality, two samples of moribund larvae have been collected (19 and 29 days of age) and fixed in 4% neutral buffered formalin. The immunohistochemical tests, using two monoclonal antibodies anti-VER (supplied from the Lombardia and Emilia IZS), were performed. The histopathological observations have put in evidence the presence of the characteristic vacuolar lesions of the central nervous system and peripheral ascribable to VER, localized above all in optic lobe, medulla oblongata, spinal verve chord and in the retinal layers (outer and inner nuclear layer). The immunoperoxidase has confirmed the presence of the virus in the tissues, showing a strongly positivity close to the lesions, characterised by the intense brown diaminobenzidine staining. After the existing literature analysis, this report seems to be the first massive mortality outbreak in gilthead larvae caused by a spontaneous infection of viral encephalopathy-retinopathy in Italy
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Effect of size on quality traits of European Sea Bass (Dicentrarchus labrax L.) from floating cage
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