1,721,070 research outputs found
Transcriptomic networks of gba3 governing specification of the dopaminergic neurons in zebrafish embryos
No full textBackground Molecular networks associated with dopaminergic (DA) neurogenesis remain undefined within mammalian models. To address this issue, the transient zebrafish model lmx1al: EGFP was generated, which expresses GFP in the DA precursor cells as well as in the DA neurons of the ventral diencephalon (VD). We found that the novel pseudogene gba3 has not been well studied in zebrafish neurogenesis. Objective Crucial networks associated with gba3 transcripts were investigated because the biological functions of these networks have not been reported in DA neurogenesis in zebrafish. Methods RNA isolation and sequencing were employed with GFP-expressing cells from 20-, 22-, and 24 h post-fertilization (hpf), while subsequent transcriptomic analysis generated differentially expressed genes with DA neurogenesis (DEG-DA) list. Hierarchical cluster analysis provided absolute guidance for the collection of gba3, an essential transcript that is strictly spatiotemporally expressed during DA neurogenesis, which was proven with whole-mount in situ hybridization (WISH) and knockdown and rescue of the gba3 transcripts in zebrafish embryos. Results The gba3 transcripts were restricted to the midbrain at 24 hpf and the midbrain and pectoral fins at 30 hpf in zebrafish embryos. Functional studies with knockdown of gba3 found a diminished state in the midbrain and midbrain-hindbrain boundary (MHB) and an underdeveloped condition in the anteroposterior and dorsolateral axis relative to the wild type (WT) at 24 hpf. However, it was recovered after forced expression of gba3 transcripts at 24 hpf. Molecular markers for the DA precursors and mature neurons lmx1al, nurr1, th, and pitx3 were analyzed in the gba3 MOs. The levels of transcripts lmx1al, nurr1, and th were significantly reduced in the midbrain ventral diencephalon (VD) and hindbrain of gba3 morphants compared to the WT at 24 hpf, while expression patterns of pitx3 transcripts showed no differences in the identical regions between gba3 MOs and the controls. Conclusions We discuss transcriptional networks in which transcripts of gba3 plausibly govern the specification of dopaminergic neurogenesis in zebrafish embryos.
Energy Absorption and Stiffness of Thin and Thick-Walled Closed-Cell 3D-Printed Structures Fabricated from a Hyperelastic Soft Polymer
Get PDFThis study analyses the energy absorption and stiffness behaviour of 3D-printed supportless,
closed-cell lattice structures. The unit cell design is bioinspired by the sea urchin morphology
having organism-level biomimicry. This gives rise to an open-cell lattice structure that can be used
to produce two different closed-cell structures by closing the openings with thin or thick walls,
respectively. In the design phase, the focus is placed on obtaining the same relative density with all
structures. The present study demonstrates that closure of the open-cell lattice structure enhances the
mechanical properties without affecting the functional requirements. Thermoplastic polyurethane
(TPU) is used to produce the structures via additive manufacturing (AM) using fused filament fabrication
(FFF). Uniaxial compression tests are performed to understand the mechanical and functional
properties of the structures. Numerical models are developed adopting an advanced material model
aimed at studying the hysteretic behaviour of the hyperelastic polymer. The study strengthens
design principles for closed-cell lattice structures, highlighting the fact that a thin membrane is the
best morphology to enhance structural properties. The results of this study can be generalised and
easily applied to applications where functional requirements are of key importance, such as in the
production of lightweight midsole shoes
Design and additive manufacturing of closed cells from supportless lattice structure
Get PDFIn nature, mesoscopic or microscopic cellular structures like trabecular bone, wood, shell, and sea urchin, can have high load-carrying capacity. These cellular structures with diverse shapes, forms and designs can be mainly classified into open and closed cell cellular structures. It is difficult to replicate these natural complex lattice structures with traditional manufacturing, but additive manufacturing (AM) technology development has allowed engineers and scientists to mimic these natural structures. Fabricating close cell lattice structures is still considered difficult due to the support structure within the lattices. This paper evaluates a novel way of fabricating a close cell lattice structure with a material extrusion process. The design eliminates the need for support structures and the subsequent post-processing required to remove them. A shell-shaped close cell lattice structure bio-mimicking a sea urchin shape was introduced for the load-bearing structure application. The mechanical properties of the proposed structure, including stiffness, deformation behavior and energy absorption, were compared with those of benchmarked honeycomb and open cell sea urchin (SU) lattice structures of the same density. SU lattice structures and honeycomb periodic lattice structures with varied sizes but the same morphology and fixed density were designed and printed in polylactic acid material (PLA). Their physical characteristics, deformation behavior, and compressive properties were investigated experimentally and via finite element analysis. The effect of the unit cell size on mechanical properties was studied and discussed, and the rankings of better performances were drawn. A possible application of the closed cell is for fabricating the load bearing structure; it can also be encapsulated within a fluid to impart strength and damping characteristics
Expression patterns of prune2 is regulated by Notch and retinoic acid signaling pathways in the zebrafish embryogenesis
No full textPRUNE2 has been identified as a susceptible gene for Alzheimer's disease and a marker for leiomyosarcomas. Isoforms of Prune2 regulate neuronal cell differentiation and synaptogenesis. Although expression pattern of Prune2 has been reported in the murine brain, its expression patterns and regulation along vertebrate embryogenesis remain to be further investigated. We thus defined the expression profiles and transcriptional regulation of prune2 in zebrafish embryos. prune2 exhibits maternal expression, but is increased in later embryonic stages, and expressed in the telencephalon, epiphysis cluster, nucleus of the tract of the post optic commissure, spinal cord, cerebellum, tegmentum, anterior lateral line ganglion, posterior lateral line ganglion and rhombomeres 2 through 5. Two color WISH with a post-mitotic neuron specific marker, huC defined that prune2 is expressed in the post mitotic neurons. The level of prune2 transcripts is upregulated in Notch signaling homozygous mutant, mib1(-/-) (mib(ta52b)), indicating that Notch signaling regulates transcription of prune2. Interestingly, in silico analysis of prune2 promoter found retinoic acid (RA) response elements (AGGTCAcaTGACCA) located at -3 to -16 relative to the first exon. It turned out that RA signaling altered the expression pattern of prune2 in the hindbrain. We further propose that Prune2 might be a putative regulator for CNS development in zebrafish embryogenesis. (C) 2017 Published by Elsevier B.V.
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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