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Title: Peptidomic analysis and characterization of the venom from Conus purpurascens.
Creator: Rodriguez, Alena, Mari, Frank, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Chemistry and Biochemistry
Abstract/Description: The venom of cone snails is a potent cocktail of peptides, proteins, and other small molecules. Several of the peptides (conopeptides and conotoxins) target ion channels and receptors and have proven useful as biochemical probes or pharmaceutical leads. In this study, the venom of a fish-hunting cone snail, Conus purpurascens was analyzed for intraspecific variability; α-conotoxins from the venom were isolated by high performance liquid chromatography, identified by mass spectrometry and...
Show moreThe venom of cone snails is a potent cocktail of peptides, proteins, and other small molecules. Several of the peptides (conopeptides and conotoxins) target ion channels and receptors and have proven useful as biochemical probes or pharmaceutical leads. In this study, the venom of a fish-hunting cone snail, Conus purpurascens was analyzed for intraspecific variability; α-conotoxins from the venom were isolated by high performance liquid chromatography, identified by mass spectrometry and nuclear magnetic resonance, and tested in a electrophysiological assay in Drosophila melanogaster; the effects of diet change on venom composition was investigated. It has been determined that each specimen of C. purpurascens expresses a distinct venom, resulting in the expression of more than 5,000 unique conopeptides across the species. α- conotoxin PIA was shown to inhibit the Dα7 nicotinic acetylcholine receptor.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004403, http://purl.flvc.org/fau/fd/FA00004403
Subject Headings: Conidae -- Environmental aspects, Drosophila melanogaster, Gastropoda -- Venom, Peptides -- Structure, Venom
Format: Document (PDF)

Title: The Dynamic pH Landscape At The Drosophila NMJ Synaptic Cleft And Its Implication In Neurotransmission.
Creator: Hernandez, Roberto X., Macleod, Gregory T., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description: The intricate processes governing cellular pH and its impact on protein and cellular function have been extensively explored. However, our understanding of the pH fluctuations that occur during routine cellular activities and their potential to modulate cell function remains, particularly within the highly dynamic pH landscape of a synapse. Investigating the scale, directionality, and temporal characteristics of these activity-dependent pH fluctuations at synapses is of paramount interest, as...
Show moreThe intricate processes governing cellular pH and its impact on protein and cellular function have been extensively explored. However, our understanding of the pH fluctuations that occur during routine cellular activities and their potential to modulate cell function remains, particularly within the highly dynamic pH landscape of a synapse. Investigating the scale, directionality, and temporal characteristics of these activity-dependent pH fluctuations at synapses is of paramount interest, as it carries profound implications for neurotransmitter release and signal transduction. Employing both empirical and computational modeling methods, our research explores the dynamic pH environment within the synaptic cleft of Drosophila glutamatergic motor neuron Ib terminals during synaptic activity and reveals its significance in modulating neurotransmission. Contrary to popular belief, we discovered that these terminals undergo activity-dependent extracellular alkalinization in response to both single action potentials and burst stimulation. This surprising phenomenon was also observed at the mouse calyx of Held. We found activity-dependent alkalinization to be predominantly driven by Ca2+ movement across the postsynaptic membrane, and by targeting pH indicators to subcellular domains, we identified alkalinization to primarily occur within the cleft.
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Date Issued: 2023
PURL: http://purl.flvc.org/fau/fd/FA00014346
Subject Headings: Neurotransmission, Drosophila, Hydrogen-Ion Concentration, Motor Neurons, Optogenetics
Format: Document (PDF)

Title: Characterization of Group B Sox genes in the development of Drosophila nervous system.
Creator: Singh, Shweta, Dawson-Scully, Ken, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Sox proteins all contain a single ~70 amino acid High Mobility Group (HMG) DNA-binding domain with strong homology to that of Sry, the mammalian testisdetermining factor. In Drosophila melanogaster, there are four closely related members of the B group, Dichaete (D), Sox Neuro (Sox N), Sox 21a, and Sox 21b that each exhibit ~90% sequence identity within the HMG domain.The previous study has shown that Dichaete plays a major role in embryonic nervous system development and is expressed in...
Show moreSox proteins all contain a single ~70 amino acid High Mobility Group (HMG) DNA-binding domain with strong homology to that of Sry, the mammalian testisdetermining factor. In Drosophila melanogaster, there are four closely related members of the B group, Dichaete (D), Sox Neuro (Sox N), Sox 21a, and Sox 21b that each exhibit ~90% sequence identity within the HMG domain.The previous study has shown that Dichaete plays a major role in embryonic nervous system development and is expressed in several clusters of neurons in the brain, including intermingled olfactory LNs and central-complex neurons strongly expressed in local interneuron of the olfactory system. However, little is known about the possible expression and functions of the related group B Sox genes in the larval and adult brain. In particular, it is unclear if Sox N may function along with Dichaete in controlling the development or physiology of the adult olfactory system. Our data suggests Sox N potential role in the elaboration of the olfactory circuit formation.
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Date Issued: 2017
PURL: http://purl.flvc.org/fau/fd/FA00004907, http://purl.flvc.org/fau/fd/FA00004907
Subject Headings: Drosophila melanogaster--Physiology., Transcription factors., Gene expression., Genetic transcription., Cell cycle., Neural stem cells.
Format: Document (PDF)

Title: Developmental delays in methionine sulfoxide reductase mutants in Drosophila Melanogaster.
Creator: Hausman, William, Binninger, David, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Aging is a biological process that has many detrimental effects due to the accumulation of oxidative damage to key biomolecules due to the action of free radicals. Methionine sulfoxide reductase (Msr) functions to repair oxidative damage to methionine residues. Msr comes in two forms, MsrA and MsrB, each form has been shown to reduce a specific enantiomer of bound and free oxidized methionine. Effects of Msr have yet to be studied in the major developmental stages of Drosophila melanogaster...
Show moreAging is a biological process that has many detrimental effects due to the accumulation of oxidative damage to key biomolecules due to the action of free radicals. Methionine sulfoxide reductase (Msr) functions to repair oxidative damage to methionine residues. Msr comes in two forms, MsrA and MsrB, each form has been shown to reduce a specific enantiomer of bound and free oxidized methionine. Effects of Msr have yet to be studied in the major developmental stages of Drosophila melanogaster despite the enzymes elevated expression during these stages. A developmental timeline was determined for MsrA mutant, MsrB mutant, and double null mutants against a wild type control. Results show that the Msr double mutant is delayed approximately 20 hours in the early/mid third instar stage while each of the single mutants showed no significant difference to the wild type. Data suggests that the reasoning of this phenomenon is due to an issue gaining mass.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004200, http://purl.flvc.org/fau/fd/FA00004200
Subject Headings: Aging -- Molecular aspects, Cellular signal transduction, Drosophila melanogaster -- Genetics, Mitochondrial pathology, Mutation (Biology), Oxidative stress
Format: Document (PDF)

Title: Functional roles of L1-Cam/Neuroglian in the nervous system of Drosophila Melanogaster.
Creator: Kudumala, Sirisha, Godenschwege, Tanja A., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Neuronal cell adhesion molecules of L1 family play a critical role in proper nervous system development. Various mutations on human L1-CAM that lead to severe neurodevelopmental disorders like retardation, spasticity etc. termed under L1 syndrome. The vertebrr their roles in axon pathfinding, neurite extension and cell migration, howeverate L1CAM and its homolog in Drosophila, neuroglian (nrg) have been well studied fo, much less is known about the mechanisms by which they fine tune synaptic...
Show moreNeuronal cell adhesion molecules of L1 family play a critical role in proper nervous system development. Various mutations on human L1-CAM that lead to severe neurodevelopmental disorders like retardation, spasticity etc. termed under L1 syndrome. The vertebrr their roles in axon pathfinding, neurite extension and cell migration, howeverate L1CAM and its homolog in Drosophila, neuroglian (nrg) have been well studied fo, much less is known about the mechanisms by which they fine tune synaptic connectivity to control the development and maintenance of synaptic connections within neuronal circuits. Here we characterized the essential role of nrg in regulating synaptic structure and function in vivo in a well characterized Drosophila central synapse model neuron, the Giant Fiber (GF) system. Previous studies from our lab revealed that the phosphorylation status of the tyrosine in the Ankyrin binding FIGQY motif in the intracellular domain of Nrg iscrucial for synapse formation of the GF to Tergo-Trochanteral Motor neuron (TTMn) synapse in the GF circuit. The present work provided us with novel insights into the role of Nrg-Ank interaction in regulating Nrg function during synapse formation and maintenance. By utilizing a sophisticated Pacman based genomic rescue strategy we have shown that dynamic regulation of the Neuroglian–Ankyrin interaction is required to coordinate transsynaptic development in the GF–TTMn synapse. In contrast, the strength of Ankyrin binding directly controls the balance between synapse formation and maintenance at the NMJ. Human L1 pathological mutations affect different biological processes distinctively and thus their proper characterization in vivo is essential to understand L1CAM function. By utilizing nrg14;P[nrg180ΔFIGQY] mutants that have exclusive synaptic defects and the previously characterized nrg849 allele that affected both GF guidance and synaptic function, we were able to analyze pathological L1CAM missense mutations with respect to their effects on guidance and synapse formation in vivo. We found that the human pathological H210Q, R184Q and Y1070C, but not the E309K and L120V L1CAM mutations affect outside-in signaling via the FIGQY Ankyrin binding domain which is required for synapse formation and not for axon guidance while L1CAM homophilic binding and signaling via the ERM motif is essential for axon guidance in Drosophila.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004131, http://purl.flvc.org/fau/fd/FA00004131
Subject Headings: Cell adhesion molecules, Cellular signal transduction, Cognitive neuroscience, Cognitive neuroscience, Drosophila melanogaster, Molecular neurobiology
Format: Document (PDF)

Title: Functional Stress Resistance: The Role of Protein Kinase G in Modulating Neuronal Excitability in Caenorhabditis Elegans and Drosophila Melanogaster.
Creator: Kelly, Stephanie Suzanne, Dawson-Scully, Ken, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Diseases such as epilepsy, pain, and neurodegenerative disorders are associated with changes in neuronal dysfunction due to an imbalance of excitation and inhibition. This work details a novel electroconvulsive seizure assay for C. elegans using the well characterized cholinergic and GABAergic excitation and inhibition of the body wall muscles and the resulting locomotion patterns to better understand neuronal excitability. The time to recover normal locomotion from an electroconvulsive...
Show moreDiseases such as epilepsy, pain, and neurodegenerative disorders are associated with changes in neuronal dysfunction due to an imbalance of excitation and inhibition. This work details a novel electroconvulsive seizure assay for C. elegans using the well characterized cholinergic and GABAergic excitation and inhibition of the body wall muscles and the resulting locomotion patterns to better understand neuronal excitability. The time to recover normal locomotion from an electroconvulsive seizure could be modulated by increasing and decreasing inhibition. GABAergic deficits and a chemical proconvulsant resulted in an increased recovery time while anti-epileptic drugs decreased seizure duration. Successful modulation of excitation and inhibition in the new assay led to the investigation of a cGMP-dependent protein kinase (PKG) which modulates potassium (K+) channels, affecting neuronal excitability, and determined that increasing PKG activity decreases the time to recovery from an electroconvulsive seizure. The new assay was used as a forward genetic screening tool using C. elegans and several potential genes that affect seizure susceptibility were found to take longer to recover from a seizure. A naturally occurring polymorphism for PKG in D. melanogaster confirmed that both genetic and pharmacological manipulation of PKG influences seizure duration. PKG has been implicated in stress tolerance, which can be affected by changes in neuronal excitability associated with aging, so stress tolerance and locomotor behavior in senescent flies was investigated. For the first time, PKG has been implicated in aging phenotypes with high levels of PKG resulting in reduced locomotion and lifespan in senescent flies. The results suggest a potential new role for PKG in seizure susceptibility and aging.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013225
Subject Headings: Caenorhabditis elegans, Drosophila melanogaster, Cyclic GMP-Dependent Protein Kinases, Seizures
Format: Document (PDF)

Title: Synaptic Rearrangements and the Role of Netrin-Frazzled Signaling in Shaping the Drosophila Giant Fiber Circuit.
Creator: Lloyd, Brandon N., Murphey, Rodney K., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: 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...
Show moreIn 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.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004758, http://purl.flvc.org/fau/fd/FA00004758
Subject Headings: Drosophila melanogaster--Cytogenetics., Genetic transcription., Transcription factors., Cellular signal transduction., Cellular control mechanisms., Cell receptors.
Format: Document (PDF)

Title: Highwire coordinates synapse formation and maturation by regulating both a map kinase cascade and the ability of the axon to respond to external cues in the giant fiber system of Drosophila Melanogaster.
Creator: Borgen, Melissa A., Murphey, Rodney K., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: The ubiquitin ligase Highwire is responsible for cell-autonomously promoting synapse formation in the Drosophila Giant Fiber system. highwire mutants show defects in synaptic function and extra branching at the axon terminal, corresponding to transient branching that occur in the course of giant synapse formation during metamorphosis. The MAP kinase pathway, including Wallenda and JNK/Basket, plus the transcription factor Jun, act to suppress synaptic function and axon pruning in a dosage...
Show moreThe ubiquitin ligase Highwire is responsible for cell-autonomously promoting synapse formation in the Drosophila Giant Fiber system. highwire mutants show defects in synaptic function and extra branching at the axon terminal, corresponding to transient branching that occur in the course of giant synapse formation during metamorphosis. The MAP kinase pathway, including Wallenda and JNK/Basket, plus the transcription factor Jun, act to suppress synaptic function and axon pruning in a dosage sensitive manner, suggesting different molecular mechanisms downstream of the MAP kinase pathway govern function and pruning. A novel role for Highwire is revealed, regulating the giant fiber axon’s ability to respond to external cues regulated by Fos. When expression of the transcription factor Fos is disrupted in the post-synaptic TTMn or surrounding midline glia of highwire mutants, the giant fiber axons show a marked increase in axon overgrowth and midline crossing. However, synaptic function is rescued by the cell nonautonomous manipulation of Fos, indicating distinct mechanisms downstream of Highwire regulating synaptic function and axon morphology.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004081, http://purl.flvc.org/fau/fd/FA00004081
Subject Headings: Cell differentiation, Cellular control mechanisms, Cellular signal transduction, Drosophila melanogaster -- Cytogenetics, Gene expression, Genetic transcription
Format: Document (PDF)

Title: Functional analysis of Drosophila and human follistatin domains and their role in growth inhibition.
Creator: Shah, Ripal., Florida Atlantic University, Haerry, Theodor E.
Abstract/Description: Follistatin (FS) proteins are highly conserved inhibitors of Activins, members of the Transforming Growth Factor beta (TGF-beta) family, which play prominent roles in patterning and cell proliferation, and can contribute to tumor formation. Comparison of FS from Drosophila (dFS) and humans (hFS) in flies shows that hFS is less active. The goal of this thesis is to test three possible mechanisms: dFS might be more stable and turn over at a lower rate, exhibit a stronger affinity for ligands,...
Show moreFollistatin (FS) proteins are highly conserved inhibitors of Activins, members of the Transforming Growth Factor beta (TGF-beta) family, which play prominent roles in patterning and cell proliferation, and can contribute to tumor formation. Comparison of FS from Drosophila (dFS) and humans (hFS) in flies shows that hFS is less active. The goal of this thesis is to test three possible mechanisms: dFS might be more stable and turn over at a lower rate, exhibit a stronger affinity for ligands, or diffuse less because of stronger interaction with the extracellular matrix. We generated chimeric proteins of dFS and hFS by exchanging individual protein domains. Our results suggest that the increased activity is likely due to ligand binding. Based on the recent structure of the hFS-Activin complex, we speculate that stronger interactions with heparin sulfate in the extracellular matrix may also contribute to the increased activity of dFS.
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Date Issued: 2005
PURL: http://purl.flvc.org/fcla/dt/13282
Subject Headings: Cell differentiation, Drosophila--Cytology, Molecular genetics, Reproduction--Physiological aspects, Glycoproteins
Format: Document (PDF)

Title: Methionine sulfoxide reductase (Msr) deficiency leads to a reduction of dopamine levels in Drosophila.
Creator: Hernandez, Caesar, Binninger, David, Weissbach, Herbert, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Biological homeostasis relies on protective mechanisms that respond to cellular oxidation caused primarily by free radical reactions. Methionine sulfoxide reductases (Msr) are a class of enzymes that reverse oxidative damage to methionine in proteins. The focus of this study is on the relationship between Msr and dopamine levels in Drosophila. Dopaminergic neurons in Drosophila have comparable roles to those found in humans. A deficit in dopamine leads to the onset of many neurological...
Show moreBiological homeostasis relies on protective mechanisms that respond to cellular oxidation caused primarily by free radical reactions. Methionine sulfoxide reductases (Msr) are a class of enzymes that reverse oxidative damage to methionine in proteins. The focus of this study is on the relationship between Msr and dopamine levels in Drosophila. Dopaminergic neurons in Drosophila have comparable roles to those found in humans. A deficit in dopamine leads to the onset of many neurological disorders including the loss of fine motor control—a neurodegenerative condition characteristic of Parkinson’s disease (PD). We found that dopamine levels in the heads of MsrAΔ/ΔBΔ/Δ mutants are significantly reduced in comparison to MsrA ⁺/⁺ B⁺/⁺ heads. In addition, wefound protein and expression levels are markedly reduced in an Msr-deficient system. Our findings suggest an important role for the Msr system in the CNS.
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Date Issued: 2014
PURL: http://purl.flvc.org/fau/fd/FA00004202, http://purl.flvc.org/fau/fd/FA00004202
Subject Headings: Cellular signal transduction, Dopamine -- Receptors, Drosophila melanogaster -- Genetics, Mitochondrial pathology, Proteins -- Chemical modification
Format: Document (PDF)

Title: Neuroprotection during acute hyperthermic stress: Role of the PKG pathway in neurons and glia in the protection of neural function in Drosophila melanogaster.
Creator: Krill, Jennifer L., Dawson-Scully, Ken, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: The human brain functions within a narrow range of temperatures and variations outside of this range incur cellular damage and death and, ultimately, death of the organism. Other organisms, like the poikilotherm Drosophila melanogaster, have adapted mechanisms to maintain brain function over wide ranges in temperature and, if exposed to high temperatures where brain function is no longer supported, these animals enter a protective coma to promote survival of the organism once the acute...
Show moreThe human brain functions within a narrow range of temperatures and variations outside of this range incur cellular damage and death and, ultimately, death of the organism. Other organisms, like the poikilotherm Drosophila melanogaster, have adapted mechanisms to maintain brain function over wide ranges in temperature and, if exposed to high temperatures where brain function is no longer supported, these animals enter a protective coma to promote survival of the organism once the acute temperature stress is alleviated. This research characterized the role of different neuronal cell types, including glia, in the protection of brain function during acute hyperthermia, specifically looking at two protective pathways: the heat shock protein (HSP) pathway and the cGMP-dependent protein kinase G (PKG) pathway. Whole animal behavioral assays were used in combination with tissue-specific genetic manipulation of protective pathways to determine the specific cell types sufficient to confer protection of neuronal function during acute hyperthermia. Using the neuromuscular junction (NMJ) preparation, calcium imaging techniques were combined with pharmacological and genetic manipulations to test the hypothesis that alterations in ion channel conductance via endogenous mechanisms regulating the cellular response to high temperature stress alter neuronal function. Expression of foraging RNAi to inhibit PKG expression in neurons or glia demonstrated protection of function during acute hyperthermia measured behaviorally through the extension of locomotor function. This extension of function with the tissue-specific inhibition of PKG was also confirmed at the cellular level using the genetically encoded calcium indicator (GECI), GCaMP3, to image calcium dynamics at the NMJ, where preparations expressing foraging RNAi could continue to elicit changes in calcium dynamics in response to stimulation. Over the course of this study, the mechanism underlying a novel glial calcium wave in the peripheral nervous system was characterized in order to elucidate glia’s role in the protection of neuronal function during acute hyperthermia.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013026
Subject Headings: Cyclic GMP-Dependent Protein Kinases, Neuroprotection, Hyperthermia, Heat shock proteins, Drosophila melanogaster
Format: Document (PDF)

Title: Neuroprotection During Acute Oxidative Stress: Role of the PKG Pathway and Identification of Novel Neuromodulatory Agents Using Drosophila Melanogaster.
Creator: Caplan, Stacee Lee, Dawson-Scully, Ken, Milton, Sarah L., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Oxidant stress and injury is inherent in many human diseases such as ischemic vascular and respiratory diseases, heart failure, myocardial infarction, stroke, perinatal and placental insufficiencies, diabetes, cancer, and numerous psychiatric and neurodegenerative disorders. Finding novel therapeutics to combat the deleterious effects of oxidative stress is critical to create better therapeutic strategies for many conditions that have few treatment options. This study used the anoxia-tolerant...
Show moreOxidant stress and injury is inherent in many human diseases such as ischemic vascular and respiratory diseases, heart failure, myocardial infarction, stroke, perinatal and placental insufficiencies, diabetes, cancer, and numerous psychiatric and neurodegenerative disorders. Finding novel therapeutics to combat the deleterious effects of oxidative stress is critical to create better therapeutic strategies for many conditions that have few treatment options. This study used the anoxia-tolerant fruit fly, Drosophila melanogaster, to investigate endogenous cellular protection mechanisms and potential interactions to determine their ability to regulate synaptic functional tolerance and cell survival during acute oxidative stress. The Drosophila larval neuromuscular junction (NMJ) was used to analyze synaptic transmission and specific motor axon contributions. Drosophila Schneider 2 (S2) cells were used to assess viability. Acute oxidative stress was induced using p harmacological paradigms that generate physiologically relevant oxidant species: mitochondrial superoxide production induced by sodium azide (NaN3) and hydroxyl radical formation via hydrogen peroxide (H2O2). A combination of genetic and pharmacological approaches were used to explore the hypothesis that endogenous protection mechanisms control cellular responses to stress by manipulating ion channel conductance and neurotransmission. Furthermore, this study analyzed a group of marine natural products, pseudopterosins, to identify compounds capable of modulating synaptic transmission during acute oxidative stress and potential novel neuromodulatory agents.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004487, http://purl.flvc.org/fau/fd/FA00004487
Subject Headings: Drosophila melanogaster -- Life cycles, Oxidative stress -- Ecophysiology, Oxidative stress -- Prevention, Protein kinases, Proteins -- Chemical modification
Format: Document (PDF)

Title: Neuroprotection during anoxic-stress in Drosophila melanogaster: the role of PKG pathway on protection of function and survival.
Creator: Benasayag Meszaros, Raquel, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Anoxia is characterized by an absence of oxygen supply to a tissue (Dawson- Scully et al., 2010). Unlike humans, Drosophila melanogaster is an organism that can survive low oxygen levels for hours without showing any pathology (Lutz et al., 2003) Under anoxia, the fruit fly loses locomotive activity, resulting in an anoxic coma (Haddad et al., 1997). In this study we investigate the influence of five variables for anoxic tolerance in adult Drosophila: 1) anoxic environment (gas vs. drowning),...
Show moreAnoxia is characterized by an absence of oxygen supply to a tissue (Dawson- Scully et al., 2010). Unlike humans, Drosophila melanogaster is an organism that can survive low oxygen levels for hours without showing any pathology (Lutz et al., 2003) Under anoxia, the fruit fly loses locomotive activity, resulting in an anoxic coma (Haddad et al., 1997). In this study we investigate the influence of five variables for anoxic tolerance in adult Drosophila: 1) anoxic environment (gas vs. drowning), 2) anoxia duration, 3) temperature (cold [3ÀC] or room temperature [21ÀC]), 4) age (young 2-9 days and old 35-39 days), and 5) PKG variation. Tolerance to anoxia is measured by the time of recovery and survival of the fruit fly from the anoxic coma. The results from this study show that short stress, low temperature, young age, and low PKG activity increased anoxic tolerance. Our findings will lay the foundation to investigate different variables, genes or pharmacological compounds that can modulate neuronal anoxic tolerance.
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Date Issued: 2013
PURL: http://purl.flvc.org/FAU/3360743
Subject Headings: Protein kinases, Oxidativie stress, Prevention, Oxidativie stress, Ecophysiology, Drosophila melanogaster, Life cycles
Format: Document (PDF)

Title: Netrin-Frazzled signaling instructs synaptogenesis and plasticity at an identified central synapse in Drosophila.
Creator: Orr, Brian, Murphey, Rodney K., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: 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...
Show moreThe 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.
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Date Issued: 2013
PURL: http://purl.flvc.org/fau/fd/FA0004041
Subject Headings: Cellular control mechanisms, Cellular signal transduction, Drosophila melanogaster -- Cytogenetics, Genetic transcription, Transcription factors
Format: Document (PDF)

Title: pH Dynamics within the Drosophila Synaptic Cleft During Activity.
Creator: Feghhi, Touhid, Lau, Andy W.C., Macleod, Gregory T., Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
Abstract/Description: Acute pH sensitivity of many neural mechanisms highlights the vulnerability of neurotransmission to the pH of the extracellular milieu. The dogma is that the synaptic cleft will acidify upon neurotransmission because the synaptic vesicles corelease neurotransmitters and protons to the cleft, and the direct data from sensory ribbon-type synapses support the acidification of the cleft. However, ribbon synapses have a much higher release probability than conventional synapses, and it’s not...
Show moreAcute pH sensitivity of many neural mechanisms highlights the vulnerability of neurotransmission to the pH of the extracellular milieu. The dogma is that the synaptic cleft will acidify upon neurotransmission because the synaptic vesicles corelease neurotransmitters and protons to the cleft, and the direct data from sensory ribbon-type synapses support the acidification of the cleft. However, ribbon synapses have a much higher release probability than conventional synapses, and it’s not established whether conventional synapses acidify as well. To test the acidification of the cleft in the conventional synapse, we used genetically encoded fluorescent pH reporters targeted to the synaptic cleft of Drosophila larvae. We observed alkalinization rather than acidification during activity, and this alkalinization was dependent on the exchange of protons for calcium at the postsynaptic membrane. A reaction-diffusion computational model of the pH dynamics at the Drosophila larval neuromuscular junction was developed to leverage the experimental data. The model incorporates the release of glutamate, ATP, and protons from synaptic vesicles into the cleft, PMCA activity, bicarbonate, and phosphate buffering systems. By means of numerical simulations, we reveal a highly dynamic pH landscape within the synaptic cleft, harboring deep but exceedingly rapid acid transients that give way to a prolonged period of alkalinization.
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Date Issued: 2023
PURL: http://purl.flvc.org/fau/fd/FA00014221
Subject Headings: Synapses, pH (Chemistry), Hydrogen-ion concentration., Synaptic Transmission, Drosophila
Format: Document (PDF)

Title: Presynaptic Determinants of Synaptic Strength and Energy Efficiency at Drosophila Neuromuscular Junctions.
Creator: Lu, Zhongmin, Macleod, Gregory, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Changes in synaptic strength underlie synaptic plasticity, the cellular substrate for learning and memory. Disruptions in the mechanisms that regulate synaptic strength closely link to many developmental, neurodegenerative and neurological disorders. Release site probability (PAZ) and active zone number (N) are two important presynaptic determinants of synaptic strength; yet, little is known about the processes that establish the balance between N and PAZ at any synapse. Furthermore, it is...
Show moreChanges in synaptic strength underlie synaptic plasticity, the cellular substrate for learning and memory. Disruptions in the mechanisms that regulate synaptic strength closely link to many developmental, neurodegenerative and neurological disorders. Release site probability (PAZ) and active zone number (N) are two important presynaptic determinants of synaptic strength; yet, little is known about the processes that establish the balance between N and PAZ at any synapse. Furthermore, it is not known how PAZ and N are rebalanced during synaptic homeostasis to accomplish circuit stability. To address this knowledge gap, we adapted a neurophysiological experimental system consisting of two functionally differentiated glutamatergic motor neurons (MNs) innervating the same target. Average PAZ varied between nerve terminals, motivating us to explore benefits for high and low PAZ, respectively. We speculated that high PAZ confers high-energy efficiency. To test the hypothesis, electrophysiological and ultrastructural measurements were made. The terminal with the highest PAZ released more neurotransmitter but it did so with the least total energetic cost. An analytical model was built to further explore functional and structural aspects in optimizing energy efficiency. The model supported that energy efficiency optimization requires high PAZ. However, terminals with low PAZ were better able to sustain neurotransmitter release. We suggest that tension between energy efficiency and stamina sets PAZ and thus determines synaptic strength. To test the hypothesis that nerve terminals regulate PAZ rather than N to maintain synaptic strength, we induced sustained synaptic homeostasis at the nerve terminals. Ca2+ imaging revealed that terminals of the MN innervating only one muscle fiber utilized greater Ca2+ influx to achieve compensatory neurotransmitter release. In contrast, morphological measurements revealed that terminals of the MN inner vating multiple postsynaptic targets utilized an increase in N to achieve compensatory neurotransmitter release, but this only occurred at the terminal of the affected postsynaptic target. In conclusion, this dissertation provides several novel insights into a prominent question in neuroscience: how is synaptic strength established and maintained. The work indicates that tension exists between energy efficiency and stamina in neurotransmitter release likely influences PAZ. Furthermore, PAZ and N are rebalanced differently between terminals during synaptic homeostasis.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004519, http://purl.flvc.org/fau/fd/FA00004519
Subject Headings: Drosophila melanogaster--Nervous system., Drosophila melanogaster--Cytogenetics., Fruit-flies--Development., Fruit-flies--Nervous system., Genetic transcription., Transcription factors., Cellular signal transduction., Cellular control mechanisms., Myoneural junction.
Format: Document (PDF)

Title: Comprehensive study of the ZAD family of zinc finger transcription factors in Drosophila melanogaster.
Creator: Krystel, Joseph., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: The zinc finger associated domain (ZAD) family of transcription factors from Drosophila melanogaster is not well described in the literature, in part because it is very difficult to study by traditional mutagenesis screens. Bioinformatic studies indicate this is due to overlapping functions remaining after a recent evolutionary divergence. I set out to use in vitro-binding techniques to identify the characteristics of the ZAD family and test this theory. I have constructed glutathione S...
Show moreThe zinc finger associated domain (ZAD) family of transcription factors from Drosophila melanogaster is not well described in the literature, in part because it is very difficult to study by traditional mutagenesis screens. Bioinformatic studies indicate this is due to overlapping functions remaining after a recent evolutionary divergence. I set out to use in vitro-binding techniques to identify the characteristics of the ZAD family and test this theory. I have constructed glutathione S-transferase (GST)-ZAD domain chimeric proteins for use in pull down protein binding assays,and GST-Zinc finger (ZnF) array domain chimera for electrophoretic mobility shift assays (EMSA). Protein binding assays indicated two putative conserved interactors, similar to the analogous KRAB system in mammals. ... Competitive bindings were carried out to show a specificity of binding conferred by the identified conserved positions. While the consensus binding sites show relatively few similarities, the predicted target genes identified by the consensus binding sites show significant overlap. The nature of this overlap conforms to the known characteristics of the ZAD family but points to a more positive selection to maintain conservation of function.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3355627
Subject Headings: Cellular signal transduction, Drosophila melanogaster, Cytogenetics, Transcription factors, Zinc-finger proteins, Synthesis, Genetic transcription, Regulation, Gene expression
Format: Document (PDF)

Title: Elucidation of the features of the zinc finger associated domain (ZAD) family of transportation factors in Drosophila melanogaster.
Creator: Krystel, Joseph., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: The zinc finger associated domain (ZAD) containing family of transcription factors is not well described in the literature, in part because it is very difficult to study by mutagenesis. We used in vitro-binding techniques to identify characteristics of the ZAD family, by constructing glutathione Stransferase (GST)-ZAD domain chimeric proteins for use in protein binding assays, and GST-Zinc finger array domain chimera for binding site selections. Protein binding assays indicated a possible...
Show moreThe zinc finger associated domain (ZAD) containing family of transcription factors is not well described in the literature, in part because it is very difficult to study by mutagenesis. We used in vitro-binding techniques to identify characteristics of the ZAD family, by constructing glutathione Stransferase (GST)-ZAD domain chimeric proteins for use in protein binding assays, and GST-Zinc finger array domain chimera for binding site selections. Protein binding assays indicated a possible shared cofactor, as seen in the analogous KRAB system in mammals. DNA binding assays have provided a consensus binding sequence for five of the ZAD proteins, consistent with previously reported work on ZAD and unpublished work on mammalian transcription factors. Research is ongoing with an additional ~50 ZAD proteins to more fully map the binding characters of ZAD proteins.
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Date Issued: 2009
PURL: http://purl.flvc.org/FAU/186768
Subject Headings: Cellular signal transduction, Drosophila melanogaster, Cytogenetics, Transcription factors, Zinc-finger proteins, Synthesis, Genetic transcription, Regulation, Gene expression
Format: Document (PDF)

Title: Identification of longitudinals lacking (LOLA) target genes in Drosophila melanogaster.
Creator: Qureshi, Bazila., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Longitudinals lacking gene (LOLA) is a transcription factor that is involved in a variety of axon guidance decisions in Drosophila melanogaster nervous system. Besides having a role as an epigenetic silencer and in the programmed cell death in Drosophila's ovary, this gene is also an example of complex transcription unit. LOLA is a transcription repressor and can generate 17 DNA - binding isoforms, through alternative splicing, each containing distinct zinc-finger proteins. This unique...
Show moreLongitudinals lacking gene (LOLA) is a transcription factor that is involved in a variety of axon guidance decisions in Drosophila melanogaster nervous system. Besides having a role as an epigenetic silencer and in the programmed cell death in Drosophila's ovary, this gene is also an example of complex transcription unit. LOLA is a transcription repressor and can generate 17 DNA - binding isoforms, through alternative splicing, each containing distinct zinc-finger proteins. This unique DNAbinding binding sequence to which LOLA-ZFP binds has been determined for four of the lola isoforms F, J, P and K. Also, bioinformatics' tool approach has been taken to identify the target genes that are regulated by these four LOLA splice variants. Future work will be done for the five other LOLA isoforms to categorize their putative DNA-binding sequences and subsequently their protein interactions.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2684893
Subject Headings: Transcription factors, Cellular signal transduction, Zinc-finger proteins, Synthesis, Genetic transcription, Regulation, Drosophila melanogaster, Cytogenetics, Gene expression
Format: Document (PDF)

Title: Identification and characterization of mutations in the Drosophila mitochondrial translation elongation factor iconoclast.
Creator: Trivigno, Catherine F., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Mitochondrial disorders resulting from defects in oxidative phosphorylation are the most common form of inherited metabolic disease. Mutations in the human mitochondrial translation elongation factor GFM1 have recently been shown to cause the lethal pediatric disorder Combined Oxidative Phosphorylation Deficiency Syndrome (COXPD1). Children harboring mutations in GFM1 exhibit severe developmental, metabolic and neurological abnormalities. This work describes the identification and extensive...
Show moreMitochondrial disorders resulting from defects in oxidative phosphorylation are the most common form of inherited metabolic disease. Mutations in the human mitochondrial translation elongation factor GFM1 have recently been shown to cause the lethal pediatric disorder Combined Oxidative Phosphorylation Deficiency Syndrome (COXPD1). Children harboring mutations in GFM1 exhibit severe developmental, metabolic and neurological abnormalities. This work describes the identification and extensive characterization of the first known mutations in iconoclast (ico), the Drosophila orthologue of GFM1. Expression of human GFM1 can rescue ico null mutants, demonstrating functional conservation between the human and fly proteins. While point mutations in ico result in developmental defects and death during embryogenesis, animals null for ico survive until the second or third instar larval stage. These results indicate that in addition to loss-of-function consequences, point mutations in ico appear to produce toxic proteins with antimorphic or neomorphic effects. Consistent with this hypothesis, transgenic expression of a mutant ICO protein is lethal when expressed during development and inhibits growth when expressed in wing discs. In addition, animals with a single copy of an ico point mutation are more sensitive to acute hyperthermic or hypoxic stress. Removal of the positively-charged tail of the protein abolishes the toxic effects of mutant ICO, demonstrating that this domain is necessary for the harmful gain-of-function phenotypes observed in ico point mutants., Further, expression of GFP-tagged constructs indicates that the C-terminal tail enhances ectopic nuclear localization of mutant ICO, suggesting that mislocalization of the protein may play a role in the antimorphic effects of mutant ICO. Taken together, these results illustrate that in addition to loss-of-function effects, gain-of-function effects can contribute significantly to the pathology caused by mutation in mitochondrial translation elongation factors.
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Date Issued: 2010
PURL: http://purl.flvc.org/FAU/2705081
Subject Headings: Drosophila melanogaster, Cytogenetics, Mutation (Biology), Mitochondrial DNA, Cell metabolism, Cellular signal transduction, Oxidation, Physiological, Genetic transcription, Regulation
Format: Document (PDF)

FAU Theses and Dissertations (39)	+ -
FAU Graduate Student Research (3)	+ -
FAU Undergraduate Student Research (3)	+ -

Drosophila melanogaster (22)	+ -
Cellular signal transduction (12)	+ -
Drosophila (9)	+ -
Genetic transcription (7)	+ -
Cytogenetics (5)	+ -

Gene expression (5)	+ -
Mutation (Biology) (5)	+ -
Oxidative stress (5)	+ -
Transcription factors (5)	+ -
Cellular signal transduction. (4)	+ -
Mitochondrial pathology (4)	+ -
Regulation (4)	+ -
Synapses (4)	+ -
Transcription factors. (4)	+ -
Cell differentiation (3)	+ -
Cellular control mechanisms (3)	+ -
Genetic transcription. (3)	+ -
Methionine Sulfoxide Reductases (3)	+ -
Proteins -- Chemical modification (3)	+ -
Sleep (3)	+ -
Synthesis (3)	+ -
Zinc-finger proteins (3)	+ -
Aging (2)	+ -
Aging -- Molecular aspects (2)	+ -
Anoxia (2)	+ -
Caenorhabditis elegans (2)	+ -
Cell receptors. (2)	+ -
Cellular control mechanisms. (2)	+ -
Cyclic GMP-Dependent Protein Kinases (2)	+ -
Drosophila melanogaster -- Cytogenetics (2)	+ -

Electronic Thesis or Dissertation (39)	+ -
poster (3)	+ -
abstract (2)	+ -

Charles E. Schmidt College of Science (37)	+ -
Department of Biological Sciences (34)	+ -
Florida Atlantic University (30)	+ -
Binninger, David (9)	+ -
Dawson-Scully, Ken (6)	+ -

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