1,721,007 research outputs found
Global alterations in mRNA polysomal recruitment in a cell model of colorectal cancer progression to metastasis
No full textTumour onset and progression are due to the accumulation
of genomic lesions, which alter gene expression and ultimately
proteome activities. These lesions are thought to
affect primarily the transcriptional control of gene
expression. In the present study, we aimed at evaluating
the genome-wide occurrence of alterations in the translational
control exploiting an isogenic, phenotypically
validated cellular model of colorectal cancer (CRC) transition
from invasive carcinoma to metastasis. In this
model, microarray profiling shows that changes in the
level of messenger ribonucleic acid (mRNA) association
with polysomes occur more than 2-fold than changes in
the level of total cellular mRNA. When common to both
the total and polysomal compartments, these changes are
also homodirectional, being amplified in magnitude at the
polysomal level. Comparison between the transcriptional
and the translational fluctuations revealed distinct signatures
of statistically over-represented gene functions,
involving the program of cell proliferation for both
levels of analysis, while the apoptosis and the translation
programs were affected mainly at translation. Looking
for an upstream determinant of translational deregulation,
we found an increase in the hyperphosphorylated
form of the 4E-BP1 protein in the metastatic cell
line, possibly resulting in an increased activation of
cap-dependent translation due to increased activity of
the eIF4E protein. Analysis of the distribution profiles
for the 50 untranslated region (50-UTR) length of the
changed genes showed an association between longer 50-UTRs and the probability for the relevant gene to
be altered translationally, consistent with enhanced
eIF4E function. This genome-wide analysis is in favour
of a model of profound alteration of translational
control in late CRC progression. It also suggests polysomal
mRNA profiles as a new, informative dimension for
the study of transcriptome imbalance in cancer
An internal ribosomal entry site in the 5’-untranslated region of p16INK4a mRNA provides a novel mechanism for the regulation of its translation
No full text
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
Neuronal ELAV proteins enhance mRNA stability by a PKCalpha-dependent pathway
No full textMore than 1 in 20 human genes bear in the mRNA 3' UTR a specific motif called the adenine- and uridine-rich element (ARE), which posttranscriptionally determines its expression in response to cell environmental signals. ELAV (embryonic lethal abnormal vision) proteins are the only known ARE-binding factors that are able to stabilize the bound mRNAs, thereby positively controlling gene expression. Here, we show that in human neuroblastoma SH-SY5Y cells, neuron-specific ELAV (nELAV) proteins (HuB, HuC, and HuD)
are up-regulated and redistributed by 15 min of treatment with the activators of PKC phorbol esters and bryostatin-1. PKC stimulation also induces nELAV proteins to colocalize with the translocated PKCalpha isozyme preferentially on the cytoskeleton, with a concomitant increase of nELAV threonine phosphorylation. The same treatment promotes stabilization of growth-associated protein 43 (GAP-43) mRNA, a well known nELAV target, and induces an early increase in GAP-43 protein concentration, again only in the cytoskeletal cell fraction. Genetic or pharmacological inactivation of PKCalpha abolishes nELAV protein cytoskeletal up-regulation, GAP-43
mRNA stabilization, and GAP-43 protein increase, demonstrating the primary role of this specific PKC isozyme in the cascade of nELAV recruitment. Finally, in vivo PKC activation is associated with an up-regulation of nELAV proteins in the hippocampal rat brain. These findings suggest a model for gene expression regulation by nELAV proteins through a PKCalpha-dependent pathway that is relevant
for the cellular programs in which ARE-mediated control plays
a pivotal role
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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