1,720,972 research outputs found
Un approccio genetico al ruolo e meccanismo d'azione del fattore trascrizionale SOX2 nelle cellule staminali neurali : delezione condizionale di SOX2 nel topo
No full textIn the mouse nervous system, Sox2 is expressed in stem cells and early precursors, and in few mature neurons (Zappone et al., 2000; Ferri et al., 2004).
Adult Sox2-deficient mice, in which Sox2 expression is decreased by about 70%, exhibit neural stem/precursor cell proliferative defects in the hippocampus and periventricular zone (Ferri et al., 2004).
I performed in vitro differentiation studies on neurosphere derived
neural cells. Neural stem cells from Sox2-deficient mice produce reduced numbers of neural progenitors.
Moreover, I found the SOX2 is important for the neural progenitors cell cycle progression. I demonstrated that SOX2 promoted the proliferation of neural stem cells through facilitating the G1/S transition with the levels of cyclin D1 and cyclin E expression in neural progenitors samples. Mash1 is an important regulator of
neurogenesis in the ventral telencephalon, where it is required both to specify neuronal precursors and to control the timing of their production. Mash1 is required for the generation of neocortical neurons with characteristics of
GABAergic interneurons. Moreover, in vivo Sox2 deficiency causes a reduction of GABAergic neurons (Cavallaro M. et al., 2008).
These observations point to a possible role for SOX2 togheter with Mash1 in the genesis of neural progenitors of GABAergic neurons. The early neural progenitors, derive from Sox2-deficient mice produce reduced numbers of MASH1 positive cells.
In vivo Chromatin immunoprecipitation assays reveal interactions of SOX2 and Mash1 in early neural progenitor cells. My data also suggest that the specific recruitment of these protein to the Mash1 in the ventral telencephalon defines the spatiotemporal activity of MASH1 in the developing nervous system
Temporal and spatial control of gene expression in early embryos of farm animals
No full textA gradual transition from oocyte-derived mRNA and proteins to full embryonic transcription characterises early embryonic development. Messenger RNAs and proteins of maternal origin are accumulated into the oocyte throughout its growth inthe ovary. Upon fertilisation, sev eral mechanisms ar e activated that controlthe appropriate use of such material and prepare for the synthesis of new products. The present review will describe some of the mechanisms active in early embryos of domestic species. Data will be presented on the control of gene expression by the 3' untranslated regions and their interaction with specialised sequences at the 5' cap end. The process of RNA sorting and localisation, initially described in different cell types and in oocytes of lower species, will also be discussed, particularly in relation to its possible role in regulating early pig development. Finally, specific genes involved in the activation of cattle embryonic transcription will be described. This brief overview will provide some suggestions on how these different mechanisms may be integrated and cooperate to ensure the correct initiation of embryonic development
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
Gene expression profile of ovine oocytes and cumulus cells with reference to premating nutrition
No full textDirected neuronal differentiation of pluripotent cell lines devived from pig parthenogenetic embryos
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