The classic guidance molecules, Netrin and its receptor Frazzled (Fra), dictate the strength of synaptic connections in the giant fiber system (GFS) of Drosophila melanogaster by regulating gap junction localization in the pre-synaptic terminal. In Netrin mutant animals the synaptic coupling between a giant interneuron and the jump motor neuron was weakened. Dye-coupling between these two neurons was severely compromised or absent. These mutants exhibited anatomically and physiologically defective synapses between the giant fiber (GF) and tergotrochanteral motor neuron (TTMn). In cases where Netrin mutants displayed apparently normal synaptic anatomy, half of the specimens exhibited physiologically defective synapses. Dye-coupling between the giant fiber and the motor neuron was reduced or eliminated, suggesting that gap junctions were disrupted in the Netrin mutants. When we examined the gap junctions with antibodies to Shaking-B Innexin (ShakB), they were significantly decreased or absent in the pre-synaptic terminal of the mutant GF. This data is the first to show that Netrin and Frazzled regulate placement of gap junctions pre-synaptically at a central synapse. In the Drosophila Giant Fiber System, we demonstrate a mechanism that ensures the monoinnervation of two homologous motor neurons by two homologous interneurons. In a scenario where both interneurons could synapse with both motor neuron targets, each interneuron exclusively synapsed with only one target and the circuit functions at normal physiological levels. This innervation pattern depended on the ratio of netrin-to-frazzled expression. When Netrin was over expressed in the system, shifting the ratio in favor of Netrin, both interneurons synapsed with both target motor neurons and physiological function was reduced. This resulted in the polyinnervationof a single target. In contrast, when Frazzled was over expressed in the system, one interneuron innervated both targets and excluded the remaining interneuron from making any synaptic contact. This resulted in a single interneuron mono-innervating both motor neurons and physiological function was mutant. The orphaned interneuron made no synaptic contact with either motor neuron target. Physiological function was only normal when the Netrin-Frazzled ratio was at endogenous levels and each GF monoinnervated one motor neuron. When we examined the gap junctions at this synapse in experimental animals, there was a significant reduction of gap junction hemichannels in the presynaptic terminal of axons that deviated from normal innervation patterns. While the synapse dyecoupled, the reduction in gap junction hemichannels reduced function in the circuit. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2013.

In the developing CNS, presynaptic neurons often have exuberant overgrowth and form excess (and overlapping) postsynaptic connections. Importantly, these excess connections are refined during circuit maturation so that only the appropriate connections remain. This synaptic rearrangement phenomenon has been studied extensively in vertebrates but many of those models involve complex neuronal circuits with multiple presynaptic inputs and postsynaptic outputs. Using a simple escape circuit in Drosophila melanogaster (the giant fiber circuit), we developed tools that enabled us to study the molecular development of this circuit; which consists of a bilaterally symmetrical pair of presynaptic interneurons and postsynaptic motorneurons. In the adult circuit, each presynaptic interneuron (giant fiber) forms a single connection with the ipsilateral, postsynaptic motorneuron (TTMn). Using new tools that we developed we labeled both giant fibers throughout their development and saw that these neurons overgrew their targets and formed overlapping connections. As the circuit matured, giant fibers pruned their terminals and refined their connectivity such that only a single postsynaptic connection remained with the ipsilateral target. Furthermore, if we ablated one of the two giant fibers during development in wildtype animals, the remaining giant fiber often retained excess connections with the contralateral target that persisted into adulthood. After demonstrating that the giant fiber circuit was suitable to study synaptic rearrangement, we investigated two proteins that might mediate this process. First, we were able to prevent giant fibers from refining their connectivity by knocking out highwire, a ubiquitin ligase that prevented pruning. Second, we investigated whether overexpressing Netrin (or Frazzled), part of a canonical axon guidance system, would affect the refinement of giant fiber connectivity. We found that overexpressing Netrin (or Frazzled) pre- & postsynaptically resulted in some giant fibers forming or retaining excess connections, while exclusively presynaptic (or postsynaptic) expression of either protein had no effect. We further showed that by simultaneously reducing (Slit-Robo) midline repulsion and elevating Netrin (or Frazzled) pre- & postsynaptically, we significantly enhanced the proportion of giant fibers that formed excess connections. Our findings suggest that Netrin-Frazzled and Slit-Robo signaling play a significant role in refining synaptic circuits and shaping giant fiber circuit connectivity. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

SK channels are small conductance Ca2+-activated K+ channels expressed throughout the CNS. SK channels modulate the excitability of hippocampal CA1 neurons by affecting afterhyperpolarization and shaping excitatory postsynaptic responses. Such SK-mediated effects on activity-dependent neuronal excitability and synaptic strength are thought to underlie the modulatory influence of SK channels on memory encoding. Here,the effect of a new SK1 selective activator, GW542573X, on hippocampal-dependent object memory, contextual and cued conditioning, and trace fear conditioning was examined. The results demonstrated that pre- but not post-training systemic administration of GW542573X impaired object memory and trace fear memory in mice 24 h after training. Contextual and cued fear memory were not disrupted. These current data suggest that activation of SK1 subtype-containing SK channels impairs long-term memory. These results are consistent with converging evidence that SK channel activation suppressed behaviorally triggered synaptic plasticity necessary for encoding hippocampal-dependent memory. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Cells process information from their environment, such as the stimuli to grow, divide, or die, via cell signaling. Deregulated processing of extracellular stimuli can lead to aberrant cell responses and cause cancer. Given that the in vivo cell environment constantly changes, it is important to understand how cells incorporate the context of their environment into their decision making processes. The idea of responding to relative, not absolute, changes in stimuli was first proposed in studies of human perception and became known as Weber's Law. Although, evidence of Weber's Law at the molecular level has been previously presented in studies of several organisms, to the best of our knowledge, it has never been explored in the case of relative sensing of extracellular stimuli in mammalian signaling cascades. The Mitogen-Activated Protein Kinase (MAPK) signaling pathway has been implicated in multiple human diseases, including cancers, and therefore cell signaling through this pathway is an important subject of research. Here we present a theoretical framework and an experimental validation of the mechanism of Weber's Law in the ability of cells to sense relative changes in the levels of extracellular stimuli in the MAPK signaling pathway. In particular, in this work we consider relative sensing in levels of Epidermal Growth Factor (EGF) in the MAPK pathway. We derive an analytical model of steady state behavior of the MAPK signaling pathway stimulated with constant doses of EGF. We demonstrate a mechanism that produces phosphorylation responses proportional to relative changes in ligand concentrations. The mechanism of Weber's Law presented here entails the retention of memory of the dose of the past chronic stimulation with EGF. The molecular mechanisms responsible for Weber's Law in MAPK signaling are likely to contribute to many other receptors signaling systems. Therefore, the mechanism of relative sensing of extracellular ligand concentrations derived here can be generalized beyond the EGF-activated MAPK signaling pathway to many other cell signaling systems. This thesis also presents a probabilistic framework to explore the parameter space of a detailed mechanistic ODE model of EGFR signaling cascades. The application of the model simulation allows us to generate probabilistic predictions of EGFR system behavior and to explore structure-to-function relationships between the model's parameter space and EGFR system responses. Overall, this work suggests an alternative view on the role of cellular endocytosis in the MAPK signaling in vivo. Specifically, traditionally viewed as a mechanism to downregulate and terminate cell signaling, endocytosis may enable cells to dynamically adjust their sensitivity to extracellular stimuli, and hence allow cells to integrate information about the past stimulations into the cell responses to the consequent stimulations and thus, cell fate decisions.

During nervous system development, thousands of distinct cell types are generated and assembled into complex circuits that control all aspects of animal cognition and behavior. Understanding what these diverse cells are, how they are generated, and what they do in the context of circuits and behavior form the fundamental efforts of the field of neuroscience. In this thesis, I investigate how the genomic organization of regulatory elements informs specific patterns of gene expression in the nervous system. In particular, I examine how distinct combinations of transcription factors interpret information encoded in the genome to control global gene expression programs in a cell-type-specific manner. In Chapter Two, I describe the establishment of a developmentally inspired transcriptional programming system to generate spinal and cranial motor neurons directly from mouse embryonic stem cells. Programmed motor neurons acquire general characteristics that mirror their in vivo counterparts, providing a robust system for studying cell fate specification in the nervous system. Combinatorial expression of cell-type-specific programming factors informs context-dependent enhancer binding and acquisition of appropriate cell-type-specific molecular and functional properties. In Chapter Three, I take advantage of this robust, experimentally accessible system to probe the chromatin-level organization and regulatory principles controlling specificity of motor neuron gene expression programs. Motor neuron genes are controlled by multiple distantly distributed enhancer constellations stretched across large regulatory domains. Using this motor neuron specification model, I discovered a unique regulatory organization controlling gene expression in the nervous system, whereby neuronal genes are controlled from uniquely complex regulatory domains acting over large distances. In Chapter Four, I extrapolate on the insights gained from studying motor neurons at a single point in time to investigate the dynamics of the regulatory environment during neuronal maturation. We demonstrate that enhancers are highly dynamic even after postmitotic specification. The dynamic nature of enhancers is dependent on combinatorial binding with new transcriptional cofactors. Overall, my results suggest that neuronal gene expression programs within a single cell type are regulated in a highly dynamic fashion by a complex set of enhancers. I propose that during development the immense cellular complexity of the nervous system is established and maintained by correspondingly complex repertoire of enhancers.

Polyglutamine disease is a class of neurodegenerative diseases, which is manifested by the atrophy of nervous system that results in dementia and/or motor dysfunction. The major pathological characteristics include progressive loss of neuronal cells as well as the appearance of insoluble nuclear inclusions in degenerating neuronal cells. Polyglutamine disease is caused by CAG triplet expansion in the genome. When translated, such expansion leads to the formation of expanded polyglutamine domain within the respective disease proteins and promotes abnormal protein conformational changes. Owing to their misfolded nature, the expanded polyglutamine proteins form insoluble nuclear inclusions. These insoluble nuclear inclusions are heterogeneous in nature, in which polyglutamine protein and molecular chaperones are the recruited components. All eukaryotic cells express molecular chaperones which function to mediate the proper folding of proteins. The recruitment of molecular chaperones into nuclear inclusions that contain misfolded triplet-expanded proteins strongly suggests the involvement of molecular chaperones in polyglutamine disease progression. It has been shown that over-expression of molecular chaperones in polyglutamine disease models can lead to a suppression of polyglutamine toxicity and a concomitant increase in the solubility of disease proteins, i.e. the solubility of polyglutamine disease protein is related to its toxicity. Intrigued by these observations, I aimed at elucidating the mechanism of polyglutamine disease pathogenesis by first studying the cellular regulation of endogenous chaperone expression in neurodegeneration in a transgenic Drosophila model of polyglutamine disease. A biphasic regulation of Hsp70 expression was observed, which the regulation was at the transcription level. Moreover, over-expression of Hsp70 could alter the endogenous Hsp70 protein and mRNA level of polyglutamine disease fly model. The study may help the understanding of how the chaperone expression is regulated under the effects of polyglutamine expression and thus to find out the mechanism of pathogenesis. In addition, cellular proteins that change in solubility other than disease protein will also be identified. Small heat shock proteins, glutathione S transferase and alpha 4 proteasome subunit, etc., showed change in solubility or expression by 2D gel electrophoresis analysis. Identifying the proteins that change in solubility or expression may help the finding of the interplay of proteins and thus the pathways involve in the mechanism of polyglutamine disease pathogenesis. Understanding pathogenic pathways can give ideas on how polyglutamine lead to the disease, up- or down-regulation of those protein interplays may provide direction and therapeutic candidates to suppress polyglutamine disease. / Huen Ngar Yee. / "September 2006." / Advisers: Ho Yin Chan; Siu Kai Kong. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1465. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 134-146). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Yau, Pak Lun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 150-167). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / List of abbreviations --- p.vi / List of figures --- p.viii / List of tables --- p.xi / Table of content --- p.xii / Chapter Chapter One: --- General introduction --- p.1 / Chapter 1.1. --- Introduction / Chapter 1.1.1. --- Tumor hypoxia --- p.2 / Chapter 1.1.2. --- Non-coding RNA --- p.6 / Chapter 1.1.3. --- Long non-coding RNAs: regulation and related diseases --- p.7 / Chapter 1.1.3.1. --- aHIF and cancer --- p.11 / Chapter 1.1.4. --- Objective --- p.11 / Chapter Chapter Two: --- Regulation of HIF-lα by aHIF --- p.13 / Chapter 2.1. --- Introduction / Chapter 2.1.1. --- aHIF: a natural antisense long non-coding RNAs --- p.14 / Chapter 2.1.2. --- The relationship between aHIF and HIF-lα --- p.15 / Chapter 2.1.3. --- HIF-lα regulation --- p.19 / Chapter 2.2. --- Materials and Methods / Chapter 2.2.1. --- Cell culture --- p.22 / Chapter 2.2.2. --- Western blot analysis --- p.22 / Chapter 2.2.3. --- RNA isolation and reverse transcription --- p.23 / Chapter 2.2.4. --- Quantitative Real-time PCR --- p.23 / Chapter 2.2.5. --- Plasmids construction --- p.24 / Chapter 2.2.5.1. --- aHIF over-expression clone --- p.24 / Chapter 2.2.5.2. --- Luciferase reporter with HIF-lα 3'UTR --- p.25 / Chapter 2.2.5.3. --- HIF-lα and PTB over-expression vector --- p.25 / Chapter 2.2.5.4. --- PTB knock-down vector --- p.30 / Chapter 2.2.6. --- Stable Clone --- p.30 / Chapter 2.2.7. --- Transfection --- p.31 / Chapter 2.2.8. --- Luciferase reporter assay --- p.31 / Chapter 2.2.9. --- Statistical analysis --- p.32 / Chapter 2.3. --- Results / Chapter 2.3.1. --- Effect of aHIF (FL) on HIF-lα expression --- p.33 / Chapter 2.3.2. --- Effect of aHIF (FL) on HIF-lα 3，UTR --- p.33 / Chapter 2.3.3. --- Effects of aHIF (OL) and aHIF (NOL) on HIF-lα level --- p.37 / Chapter 2.3.4. --- Effects of aHIF (NOL) and aHIF (OL) on HIF-lα 3，UTR --- p.39 / Chapter 2.3.5. --- Effect of aHIF (FL) on HIF-lα 3' UTR in PTBi cells --- p.41 / Chapter 2.3.6. --- Effect of aHIF (NOL) on HIF-lα 3，UTR in PTBi cells --- p.43 / Chapter 2.3.7. --- Effect of aHIF (OL) on HIF-lα 3' UTR in PTBi cells --- p.45 / Chapter 2.4 --- Discussion / Chapter 2.4.1. --- aHIF regulates HIF-la through HIF-la 3' UTR (FL) --- p.47 / Chapter 2.4.2. --- Factors involved in aHIF- HIF-lα interaction --- p.53 / Chapter Chapter Three: --- aHIF regulates drug sensitivity through BNIP3 --- p.58 / Chapter 3.1 --- Introduction / Chapter 3.1.1. --- aHIF and drug sensitivity --- p.59 / Chapter 3.1.2. --- BNIP3: its regulation and functions --- p.61 / Chapter 3.1.3. --- Taxol and its action mechanism --- p.67 / Chapter 3.1.4. --- Objective --- p.69 / Chapter 3.2. --- Materials and Methods / Chapter 3.2.1. --- Cell culture --- p.70 / Chapter 3.2.2. --- Cell viability assay --- p.70 / Chapter 3.2.3. --- Western blot analysis --- p.70 / Chapter 3.2.4. --- Plasmid construction --- p.71 / Chapter 3.2.5. --- Transfection --- p.71 / Chapter 3.2.6. --- Stable clone formation --- p.71 / Chapter 3.2.7. --- Quantitative real-time PCR --- p.71 / Chapter 3.2.8. --- Annexin V binding assay --- p.72 / Chapter 3.2.9. --- DNA fragmentation assay --- p.72 / Chapter 3.2.10. --- Detection of mitochondrial membrane potential by flow cytometry --- p.73 / Chapter 3.2.11. --- Cytochrome c and AIF translocation assay --- p.73 / Chapter 3.2.12. --- Statistical analysis --- p.74 / Chapter 3.3 --- Results / Chapter 3.3.1. --- Effect of aHIF on Taxol and vincristine sensitivity in HepG2 cells --- p.75 / Chapter 3.3.2. --- Effect of HIF-lαi on Taxol and vincristine sensitivity in HepG2 cells --- p.75 / Chapter 3.3.3. --- Effect of aHIF on Taxol-induced apoptosis --- p.78 / Chapter 3.3.4. --- HIF-1α regulation of BNIP3 expression --- p.78 / Chapter 3.3.5. --- Effect of aHIF on BNIP3 expression --- p.81 / Chapter 3.3.6. --- BNIP3 expression in BNIP3i stable transfectant --- p.81 / Chapter 3.3.7. --- The response of BNIP3i cells towards Taxol and vincrisinte --- p.84 / Chapter 3.3.8. --- Effect of BNIP3 on Taxol and vincristine sensitivity in BNIP3i cells --- p.84 / Chapter 3.3.9. --- Taxol- or vincristine- induced apoptosis in BNIP3i cells --- p.87 / Chapter 3.3.10. --- "Effects of aHIF, HIF-lα and BNIP3 on Taxol-induced apoptosis in HepG2 cells" --- p.89 / Chapter 3.3.11. --- Caspases activation in Taxol - or vincristine - induced apoptosis in BNIP3i cells --- p.91 / Chapter 3.3.12. --- Mitochondrial membrane depolarization in Taxol - or vincristine - induced apoptosis in BNIP3i cells --- p.91 / Chapter 3.3.13. --- AIF and cytochrome c expressions in BNIP3i cells --- p.92 / Chapter 3.3.14. --- Effect of aHIF on other chemo- and radio-therapeutics in HepG2 cells --- p.96 / Chapter 3.3.15. --- Effect of HIF-lα on other chemo- and radio-therapeutics in HepG2 cells --- p.96 / Chapter 3.3.16. --- BNIP3i cells became more sensitivity to a number of drugs --- p.99 / Chapter 3.3.17. --- BNIP3i became more resistance to some drugs --- p.99 / Chapter 3.4 --- Discussion / Chapter 3.4.1. --- aHIF affected Taxol sensitivity through BNIP3 --- p.102 / Chapter 3.4.2. --- Mechanism of BNIP3 regulated Taxol or vincristine induced apoptosis --- p.106 / Chapter 3.4.3. --- Possible roles of BNIP3 in response to other therapeutics --- p.110 / Chapter Chapter Four: --- aHIF regulation of tumorigenesis --- p.116 / Chapter 4.1 --- Introduction / Chapter 4.1.1. --- aHIF in cancer biology --- p.117 / Chapter 4.1.2. --- Ras proteins --- p.118 / Chapter 4.1.3. --- K-Ras and cancers --- p.121 / Chapter 4.1.4. --- Regulation of Ras --- p.122 / Chapter 4.2 --- Materials and Methods / Chapter 4.2.1. --- Cell culture --- p.124 / Chapter 4.2.2. --- Western blot analysis --- p.124 / Chapter 4.2.3. --- Plasmids construction --- p.124 / Chapter 4.2.4. --- Transfection --- p.124 / Chapter 4.2.5. --- Cell growth assay --- p.124 / Chapter 4.2.6. --- Soft agar assay --- p.125 / Chapter 4.2.6. --- Statistical analysis --- p.125 / Chapter 4.3 --- Results / Chapter 4.3.1. --- Effect of aHIF and HIF-lα on cell proliferation --- p.127 / Chapter 4.3.2. --- Effect of aHIF and HIF-lα on anchorage-independent growth --- p.127 / Chapter 4.3.3. --- Effect of aHIF and HIF -lα on K-Ras expression --- p.130 / Chapter 4.3.4. --- Effect of FTS on cell transfected with aHIF or HIF-lα --- p.130 / Chapter 4.4 --- Discussion / Chapter 4.4.1. --- Role of aHIF in tumorigenesis --- p.133 / Chapter 4.4.2. --- Proposed pathways of aHIF-regulated tumorigenesis --- p.136 / Chapter Chapter Five: --- General discussion and conclusion --- p.140 / Chapter 5.1 --- General discussion --- p.141 / Chapter 5.2 --- Conclusion --- p.146 / Chapter 5.3 --- Future perspectives --- p.147 / Chapter 5.3.1 --- Role ofPTB in aHIF-HIF-lα interaction --- p.147 / Chapter 5.3.2 --- Effect of aHIF (OL) on HIF-lα mRNA 3' UTR --- p.147 / Chapter 5.3.3 --- Effect ofaHIF on AIF --- p.148 / Chapter 5.3.4 --- Confirmation of the involvement of K-Ras --- p.148 / Chapter Chapter Six --- References --- p.150 / Chapter 6.1 --- References --- p.151

Errata inserted inside back cover. / "August 2002" / Includes bibliographical references (leaves 146-174) / 177 leaves, [91 leaves of plates] : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Molecular Biosciences, 2002

<p>As projects play a key role in implementing strategy, organizations of all kinds implement projects. Further, as the importance of the projects grow, management of the same also becomes crucial in terms of monitoring and controlling. However, as non-project based organizations lack distinctive project management approach, their project are controlled and monitored by the inherent management control system. While, several studies have highlighted that different organization control mechanisms are exercised at varying degree, there is a dearth of study done in project context. However, one recent study done by Nieminen and Lehtonen (2008) in a program context focusing only in organizational change revealed three organizational control mechanisms and 23 control tools being exercised as varying degree in four case programs. As several studies in the project management context highlight the need to tailor the approach according to the project types, this study focuses on understanding how the control mechanisms vary across different types of projects executed by non-project based organizations employing the project classification developed by Turner and Cochrane (1993).</p><p>A qualitative study employing semi-structured interview was conducted with eight project managers of respective projects implemented by seven companies from China and Nepal. Based on the feedback given by the concerned project managers, the study revealed distinct organizational control mechanisms dominated distinct project types in rolling out a successful project, even though there was presence of all types of organizational control mechanisms in the sampled projects. Further, the application of the control tools within the control mechanism varied even across projects of similar type.</p>

Thesis (Ph. D. in Cell and Developmental Biology)--Vanderbilt University, May 2007. / Title from title screen. Includes bibliographical references.