1,720,965 research outputs found
Caratterizzazione dell'espressione e della funzione delle Emiline in topo ed in zebrafish
Full text linkEmilins are a family of glycoproteins of the extracellular matrix with common structural organization and containing a characteristic N-terminal cysteine-rich domain. During my PhD, I studied expression and function in zebrafish and in mice of the corresponding genes, and I focused my attention on Emilin3, coding for the only component of the family lacking the C-terminal gC1q domain.
As concerns my work on zebrafish, by database searching we identified and cloned eight members of this gene family. Their expression pattern during embryonic development, analyzed by whole-mount in situ hybridization, is characteristic and partially overlapping with expression of Emilins in mice. The most interesting pattern is the one of Emilin-3: while other Emilin genes reveal a mesenchymal or cardiovascular expression profile, the two zebrafish genes coding for Emilin-3 are abundantly expressed at early stages in the notochord and in the floor plate and at later stages in the branchial arches. This suggests that Emilin-3 may play a distinct role in the extracellular matrix, in comparison with other members of Emilin family. To gain insight into the function of these genes in vivo, we started functional studies by in situ hybridization of embryos in which relevant molecular pathways are blocked by treatment with specific drugs and by microinjection of mRNA and morfolino oligonucleotides in fertilized oocytes.
Concerning the studies in mice, these experiments represented a large part of my PhD work and they were concentrated on the gene coding for Emilin-3. In the past years, targeted Emilin3 gene inactivation in murine embryonic stem (ES) cells was already undertaken in the laboratory where I performed my PhD work. However, generation of Emilin3 knockout mice was unsuccesful and these previous attempts revealed that, unlike other Emilins, targeted inactivation of the Emilin3 gene is particularly difficult. The frequency of homologous recombination of this gene is extremely low and transmission of the inactivated allele to the F1 generation was not reached, probably also due to karyotypic instability of targeted ES cell clones. Therefore, I carried out a new Emilin3 gene targeting approach, performed by means of a large scale experiment with a new ES cell line. I transfected euploid R1 ES cells with a Emilin3 targeting construct and, after double positive-negative selection, 1505 clones were isolated; 995 of these individual cell clones were further expandend and investigated for identifying clones in which a correct homologous recombination event had occurred. With such large number of clones, molecular analysis by Southern blotting, a standard but time- and money-consuming procedure, was not an easily affordable screening method for detecting rare homologus recombinant clones. Therefore, I set up an optimal screening procedure by PCR. Six positive ES clones were identified, and after additional characterization four of them were used for generation of chimeric mice by microinjection of ES cells into host blastocysts and implant in foster females. By crossing these chimeric mice, I obtained for two independent clones heterozygous and finally homozygous Emilin3 knockout mice, and I started to undertake the phenotypic analysis of Emilin-3 null mice. Finally, I also performed a detailed karyotypic analysis of targeted Emilin3 ES clones introduced in vivo, in comparison to the original ES cell line and other mutant ES cell clones, with the aim of correlating the karyotype of ES cells with their ability to transmit the inactivated allele to the germ-line
Expression pattern and functional studies of Emilin genes in zebrafish
No full textExpression pattern and functional studies of Emilin genes in zebrafis
Expression pattern and function analysis of Emilin genes in zebrafish
No full textExpression pattern and function analysis of Emilin genes in zebrafis
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
Emilin genes are duplicated and dynamically expressed during zebrafish embryonic development
No full textEmilins are a family of extracellular matrix proteins with common structural organization and containing a characteristic N-terminal cysteine-rich domain. The prototype of this family, Emilin-1, is found in human and murine organs in association with elastic fibers, and other emilins were recently isolated in mammals. To gain insight into these proteins in lower vertebrates, we investigated the expression of emilins in the fish Danio rerio. Using sequence similarity tools, we identified eight members of this family in zebrafish. Each emilin gene has two paralogs in zebrafish, showing conserved structure with the human ortholog. In situ hybridization revealed that expression of zebrafish emilin genes is regulated in a spatiotemporal manner during embryonic development, with overlapping and site-specific patterns mostly including mesenchymal structures. Expression of certain emilin genes in peculiar areas, such as the central nervous system or the posterior notochord, suggests that they may play a role in key morphogenetic processes
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
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