1,720,971 research outputs found
The story of SPATA2 (Spermatogenesis-associated Protein 2): from Sertoli cells to pancreatic beta-cells.
Full text linkIn an attempt to isolate new spermatogenesis-associated genes, pd1 was initially identified and cloned as a novel human cDNA sequence from testis cDNA library. The novel gene was submitted to GenBank under accession n degrees U28164 in 1996. PD1 expression was demonstrated at the Sertoli cell level with a production which appeared to be under the influence of neighbouring spermatogenic cells. The rat orthologue of human pd1 was further cloned and, according to the Gene Nomenclature Committee, was renamed spata2 (spermatogenesis-associated protein 2) gene on the basis of its FSH-dependent up-regulation and developmental expression. The analysis of the human and rat cDNA sequences disclosed an open reading frame for a protein of 520 and 511 amino acids respectively, with an overall identity of 85%. Subsequently, a zebrafish orthologue of the human spata2 gene was identified. The consensus open reading frame (1650 bp) encodes a polypeptide of 550 amino acids, which shares 37% identity with the human spata2. By means of whole-mount in situ hybridisation it has been shown that spata2 transcripts are maternally derived and become strongly localised in the central nervous system at early developmental stages. At the same time, RT-PCR analysis demonstrated that several adult zebrafish tissues expressed high level of spata2 mRNA providing evidence that this gene may have a broader function than previously described. More recently, novel findings have highlighted a potential role of spata2 during pancreatic development and beta-cell proliferation. In this review we will discuss spata2 gene expression and regulation as well as focus on novel evidence, which suggests a role for this protein in pancreatic beta-cell function
Imposex in H. Trunculus in the Lagoon of Venice: the role of TBT and other endocrine disruptors (PCB, Pesticides, PAH)
No full textGoing 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
Organochlorine compounds (Polychlorinated biphenyls and Pesticides) and Polycyclic aromatic hydrocarbons in populations of Hexaplex trunculus affected by imposex in the lagoon of Venice, Italy
Full text linkConcentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides, and polycyclic aromatic hydrocarbons (PAHs) were measured in gastropods from the Lagoon of Venice, Italy. The visceral coil and the rest of the soft body of organisms (Hexaplex trunculus) sampled at two stations inside the lagoon and three stations on the seaward side were analyzed to evaluate their contamination levels. Preferential accumulation of PCBs and pesticides in the visceral coil (>80%) compared with the rest of the soft body was observed, whereas on average, PAHs showed no preferential partitioning. Differences between levels of organochlorine contaminants in the gastropods highlighted a gradient of pollution from the stations inside the lagoon (PCBs, 45-363 ng/g; pesticides, 4-51 ng/g) to the sea (PCBs, 13-131 ng/g; pesticides, 2-29 ng/g). The possible role of the three classes of contaminants, in addition to that of organotin compounds (OTCs), previously analyzed in the same samples, in causing one of the anatomic modifications because of imposex in this gastropod also was studied. A modeling approach by partial least squares (PLS) in latent variables was applied to explain the penis length of imposex-affected females with concentrations of organic pollutants. The synergistic role of PCBs, pesticides, and OTCs was evidenced, whereas the contribution of PAHs appeared to be very low
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