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Analisi dell’espressione e della funzione del gene zf-prox1 durante lo sviluppo di zebrafish
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prox1 directs the proper development of the posterior tuberculum catecholaminergic neurons modulating otp1 expression
No full textCaratterizzazione funzionale del gene numb durante la formazione del sistema vascolare/ematopoietico in zebrafish
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Ectopic expression and knockdown of a zebrafish sox21 reveal its role as a transcriptional repressor in early development
No full textSox proteins are DNA-binding proteins belonging to the HMG box superfamily and they play key roles in animal embryonic development.
Zebrafish Sox21a is part of group B Sox proteins and its chicken and mouse orthologs have been described as transcriptional repressor and
activator, respectively, in two different target gene contexts. Zebrafish sox21a is present as a maternal transcript in the oocyte and is mainly
expressed at the developing midbrain–hindbrain boundary from the onset of neurulation. In order to understand its role in vivo, we
ectopically expressed sox21a by microinjection. Ectopic expression of full length sox21a leads to dorsalization of the embryos. A subset of
the dorsalized embryos shows a partial axis splitting, and hence an ectopic neural tube, as an additional phenotype. At gastrulation, injected
embryos show expansion of the expression domains of organizer-specific genes, such as chordin and goosecoid. Molecular markers used in
somitogenesis highlight that sox21a-injected embryos have shortened AP axis, undulating axial structures, enlarged or even radialized
paraxial territory. The developmental abnormalities caused by ectopic expression of sox21a are suggestive of defects in convergence–
extension morphogenetic movements. Antisense morpholino oligonucleotides, designed to functionally knockdown sox21a, cause
ventralization of the embryos. Moreover, gain-of-function experiments with chimeric constructs, where Sox21a DNA-binding domain is
fused to a transcriptional activator (VP16) or repressor (EnR) domain, suggests that zebrafish Sox21a acts as a repressor in dorso-ventral
patterning
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
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