1,721,041 research outputs found
New Methods for Characterizing the Complex Neural Circuitry of the Adult Drosophila Brain
No full text"Recently improved genetic mosaic methods permit unprecedented resolution for study of neural circuitry formation in Drosophila melanogaster. This study utilizes new mosaic methods to investigate conserved mechanisms that underlie the development of adult-specific neurons. In addition to providing several novel insights about the genetics of neural circuitry development, this study also provides a framework for increased resolution in examination of lineage and morphology in the Drosophila brain. First, mosaic analysis with a repressible cell marker (MARCM) reveals stereotyped lineage and morphogenesis in the ellipsoid body (EB), a center of locomotor regulation, resembling development of the mushroom bodies (MB's), sites involved heavily in olfactory learning. In addition, EB neuron birth and axon development are widely separated in time making them ideal model neurons for further studies. Second, comparative genetic mosaic analysis of EB and dorsal cluster (DC) neurons suggests that TGF-beta signaling is widely required for maturation and morphogenesis of post-mitotic adult-specific neurons. Third, combined application of MARCM with a newly developed technique, called ""Flip-out"" MARCM, reveals that the Drosophila Down syndrome cell adhesion molecule (Dscam) is required for suppressing ectopic bifurcation MB axons and for promoting divergent guidance of growth cones. Knockout of Dscam in EB neurons reveals a general role in formation and guidance of axonal branches. Finally, combining mosaic methods to study both cellular genetic requirements and phenotypes suggest a non-autonomous requirement for the atypical receptor tyrosine kinase (RTK), Linotte/Derailed (Lio/Drl), in patterning MB axon lobe architecture. In the development of MB circuitry, Lio/Drl may act to counter Wnt5 signaling, which appears to be generally required for axon extension across the brain midline."Made available in DSpace on 2015-09-28T15:03:17Z (GMT). No. of bitstreams: 2
license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5)
3270069.pdf: 3705871 bytes, checksum: 0714bd4826cef34609bf8d58b567b6d1 (MD5)
Previous issue date: 2007Embargo set by: Seth Robbins for item 87590
Lift date: Forever
Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDsRestricted to the U of I community idenfinitely during batch ingest of legacy ETDsU of I Only141 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007
Requirement of Baboon/dsmad2-Mediated Tgf-Beta/activin Signaling for Post-Mitotic Neuronal Development in the Drosophila Brain
No full text94 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.The intermingling of larval functional neurons with adult-specific neurons during metamorphosis contributes to the development of the Drosophila adult brain. This study provides evidence for cell-autonomous involvement of widespread Baboon/dSmad2-mediated TGF-beta/Activin signaling in various neuronal developmental processes prior to the prepupal ecdysone peak. Interestingly, this stage-specific Babo/dSmad2 signaling appears to accelerate maturation and morphogenesis of post-mitotic neurons throughout the entire nervous system. Loss of Babo/dSmad2 drastically delays adult-specific neurons' initial morphogenesis, while Babo/dSmad2 acts to assure timely expression of EcR-B1 in larval functional neurons. This study, thus, suggests that TGF-beta signaling prior to metamorphosis may be widely required to prepare neurons for the rapidly changing environment present during metamorphosis. Given that many vertebrate TGF-beta signaling molecules are dynamically present in the postnatal brain, it is possible that similar mechanisms may help modulate neural circuitry in higher organisms during periods of extensive morphogenesis.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD
Mosaic Analysis of Neurogenesis and Neuronal Morphogenesis in Drosophila Learning and Memory Center Mushroom Bodies
No full text119 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005.Based on the above findings, a forward genetic screen using MARCM (m&barbelow;osaic a&barbelow;nalysis with r&barbelow;epressible c&barbelow;ell m&barbelow;arker) system, which uniquely labels wild type or homozygous mutant single-cell or subcell lineages born at specific developmental stages, was performed for identification of novel genes involved in MB neuron development. Of 1200 mutant chromosome arms of 2L screened, two interesting genes were identified and their functions in MB neuron development were further characterized. These two genes are Cul3 and Chinmo. Cul3 encodes a scaffold protein for E3 ubiquitin ligase. Phenotypic analysis demonstrates that Cul3 is required for proper axon arborization and dendritic elaboration of MB neurons. Chinmo is a novel BTB-zinc finger protein. Functional analysis shows that Chinmo is an important intrinsic factor involved in birth order-dependent specification of neuronal identities. These findings provide news insights into the mechanisms underlying neuronal morphogenesis and the generation of neuronal diversity.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD
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
Requirement of Baboon/dsmad2-Mediated Tgf-Beta/activin Signaling for Post-Mitotic Neuronal Development in the Drosophila Brain
No full textThe intermingling of larval functional neurons with adult-specific neurons during metamorphosis contributes to the development of the Drosophila adult brain. This study provides evidence for cell-autonomous involvement of widespread Baboon/dSmad2-mediated TGF-beta/Activin signaling in various neuronal developmental processes prior to the prepupal ecdysone peak. Interestingly, this stage-specific Babo/dSmad2 signaling appears to accelerate maturation and morphogenesis of post-mitotic neurons throughout the entire nervous system. Loss of Babo/dSmad2 drastically delays adult-specific neurons' initial morphogenesis, while Babo/dSmad2 acts to assure timely expression of EcR-B1 in larval functional neurons. This study, thus, suggests that TGF-beta signaling prior to metamorphosis may be widely required to prepare neurons for the rapidly changing environment present during metamorphosis. Given that many vertebrate TGF-beta signaling molecules are dynamically present in the postnatal brain, it is possible that similar mechanisms may help modulate neural circuitry in higher organisms during periods of extensive morphogenesis.Made available in DSpace on 2015-09-28T15:03:16Z (GMT). No. of bitstreams: 2
license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5)
3202199.pdf: 2013861 bytes, checksum: ca63b3cf1df6a22778709fa7fd97eb26 (MD5)
Previous issue date: 2005Embargo set by: Seth Robbins for item 87585
Lift date: Forever
Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDsRestricted to the U of I community idenfinitely during batch ingest of legacy ETDsU of I Only94 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2005
New Methods for Characterizing the Complex Neural Circuitry of the Adult Drosophila Brain
No full text141 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2007.Recently improved genetic mosaic methods permit unprecedented resolution for study of neural circuitry formation in Drosophila melanogaster. This study utilizes new mosaic methods to investigate conserved mechanisms that underlie the development of adult-specific neurons. In addition to providing several novel insights about the genetics of neural circuitry development, this study also provides a framework for increased resolution in examination of lineage and morphology in the Drosophila brain. First, mosaic analysis with a repressible cell marker (MARCM) reveals stereotyped lineage and morphogenesis in the ellipsoid body (EB), a center of locomotor regulation, resembling development of the mushroom bodies (MB's), sites involved heavily in olfactory learning. In addition, EB neuron birth and axon development are widely separated in time making them ideal model neurons for further studies. Second, comparative genetic mosaic analysis of EB and dorsal cluster (DC) neurons suggests that TGF-beta signaling is widely required for maturation and morphogenesis of post-mitotic adult-specific neurons. Third, combined application of MARCM with a newly developed technique, called "Flip-out" MARCM, reveals that the Drosophila Down syndrome cell adhesion molecule (Dscam) is required for suppressing ectopic bifurcation MB axons and for promoting divergent guidance of growth cones. Knockout of Dscam in EB neurons reveals a general role in formation and guidance of axonal branches. Finally, combining mosaic methods to study both cellular genetic requirements and phenotypes suggest a non-autonomous requirement for the atypical receptor tyrosine kinase (RTK), Linotte/Derailed (Lio/Drl), in patterning MB axon lobe architecture. In the development of MB circuitry, Lio/Drl may act to counter Wnt5 signaling, which appears to be generally required for axon extension across the brain midline.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD
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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