Biology Commons^™

The Functional Conservation Of Frazzled In Insects, Benjamin Wadsworth

Graduate Theses and Dissertations

Axons in the developing embryo receive and react to signals that direct their growth to reach target tissues at specified locations. The signal pathways that direct midline crossing of axons during embryonic development have been comprehensively examined in the past years using the Drosophila ventral nerve cord or the spinal cord as a model system. A number of these signaling mechanisms are conserved, however disparities have been found between species in general strategy or the molecular signals controlling the response of axons to guidance cues.

The Netrin-Frazzled pathway has been shown to aid in midline crossing of axons in the …

The Effects Of A Bacterial Endotoxin On Behavior And Sensory-Cns-Motor Circuits In Drosophila Melanogaster, Oscar Istas, Abigail Greenhalgh, Robin L. Cooper

Biology Faculty Publications

The effect of bacterial sepsis on animal behavior and physiology is complex due to direct and indirect actions. The most common form of bacterial sepsis in humans is from gram-negative bacterial strains. The endotoxin (lipopolysaccharide, LPS) and/or associated peptidoglycans from the bacteria are the key agents to induce an immune response, which then produces a cascade of immunological consequences. However, there are direct actions of LPS and associated peptidoglycans on cells which are commonly overlooked. This study showed behavioral and neural changes in larval Drosophila fed commercially obtained LPS from Serratia marcescens. Locomotor behavior was not altered, but feeding …

Mechanisms Of Oriented Cell Division And Their Roles In Tissue Development, Evan Blake Dewey

Biology ETDs

Properly executed cell division is crucial to development, maintenance, and longevity of multicellular organisms. Defects in both symmetric and asymmetric divisions can lead to improper developmental patterning, as well as genomic instability, disruption of tissue homeostasis, and cancer. Our research focuses on how regulators orchestrate proper cell divisions. Mushroom Body Defect (Mud) is one such regulator, and here we describe how Mud is regulated via the Hippo signaling pathway kinase Warts (Wts), showing Wts phosphorylates Mud to enhance interaction with the polarity protein Partner of Inscuteable, promoting spindle orientation activity. We next focus on another regulator, Shortstop (Shot), describing a …

The Role Of Dunc13 In Ethanol Tolerance, Yusuke Wachi

Electronic Theses and Dissertations

Although the effects of ethanol on presynaptic activity have been studied, the molecular mechanisms and the changes in gene expression which are responsible for inducing ethanol tolerance are unclear. Munc13-1 is an active-zone protein that is essential for presynaptic vesicle fusion. This protein interacts with vesicle fusion machinery at presynaptic active zones in the mammalian brain. The C1 domain of Munc13-1 binds diacylglycerol (DAG), which helps membrane localization of this protein and promotes vesicle fusion, facilitating synaptic vesicle release. Previously, it was shown that ethanol binds to the C1 domain of Munc13-1 in vitro at concentrations below 100 mM (Das …

The Effects Of A Ketone Body On Synaptic Transmission, Alexandra Elizabeth Stanback

Theses and Dissertations--Biology

The ketogenic diet is commonly used to control epilepsy, especially in cases when medications cannot. The diet typically consists of high fat, low carb, and adequate protein and produces a metabolite called acetoacetate. Seizure activity is characterized by glutamate excitotoxicity and therefore glutamate regulation is a point of research for control of these disorders. Acetoacetate is heavily implicated as the primary molecule responsible for decreasing glutamate in the synapse; it is believed that acetoacetate interferes with the transport of glutamate into the synaptic vesicles. The effects on synaptic transmission at glutamatergic synapses was studied in relation to the ketogenic diet …

Polyglutamine Repeat Proteins Disrupt Actin Structure In Drosophila Photoreceptors., Annie Vu, Tyler Humphries, Sean Vogel, Adam Haberman

Biology: Faculty Scholarship

Expansions of polygutamine-encoding stretches in several genes cause neurodegenerative disorders including Huntington's Disease and Spinocerebellar Ataxia type 3. Expression of the human disease alleles in Drosophila melanogaster neurons recapitulates cellular features of these disorders, and has therefore been used to model the cell biology of these diseases. Here, we show that polyglutamine disease alleles expressed in Drosophila photoreceptors disrupt actin structure at rhabdomeres, as other groups have shown they do in Drosophila and mammalian dendrites. We show this actin regulatory pathway works through the small G protein Rac and the actin nucleating protein Form3. We also find that Form3 has …

The Acyl-Coa Synthetase, Pudgy, Promotes Sleep And Is Required For The Homeostatic Response To Sleep Deprivation, Matthew S. Thimgan, Natlie Kress, John Lisse, Courtney Fiebelman, Thomas Hilderbrand

Biological Sciences Faculty Research & Creative Works

The regulation of sleep and the response to sleep deprivation rely on multiple biochemical pathways. A critical connection is the link between sleep and metabolism. Metabolic changes can disrupt sleep, and conversely decreased sleep can alter the metabolic environment. There is building evidence that lipid metabolism, in particular, is a critical part of mounting the homeostatic response to sleep deprivation. We have evaluated an acyl-CoA synthetase, pudgy (pdgy), for its role in sleep and response to sleep deprivation. When pdgytranscript levels are decreased through transposable element disruption of the gene, mutant flies showed lower total sleep times …

Identification Of Raw As A Regulator Of Glial Development, Diana Luong, Luselena Perez, Jennifer Mierisch

Biology: Faculty Publications and Other Works

Glial cells perform numerous functions to support neuron development and function, including axon wrapping, formation of the blood brain barrier, and enhancement of synaptic transmission. We have identified a novel gene, raw, which functions in glia of the central and peripheral nervous systems in Drosophila. Reducing Raw levels in glia results in morphological defects in the brain and ventral nerve cord, as well as defects in neuron function, as revealed by decreased locomotion in crawling assays. Examination of the number of glia along peripheral nerves reveals a reduction in glial number upon raw knockdown. The reduced number of …

Regulation Of Epithelial Proliferation And Migration By Apical-Basal Polarity Proteins, Gregory Vincent Schimizzi

Arts & Sciences Graduate Student Theses and Dissertations

Epithelial cells line all the outside surfaces of the body where they perform essential roles in maintaining homeostasis. In addition, epithelial tissues are implicated in many disease processes and are the most common tissue type to give rise to human cancer. Therefore, a thorough understanding of epithelial development and homeostasis has broad implications for understanding human development, health, and disease. The establishment and maintenance of apical-basal polarity is a defining characteristic and essential feature of functioning epithelia. Proper apical-basal polarity (ABP) is required for epithelial tissues to carry out their functions, which include absorption, secretion, barrier formation, and collective migration. …

In Vivo Structure-Function Analysis Of Drosophila Robo1, An Axon Guidance Receptor Critical For Midline Repulsive Signaling In The Embryonic Central Nervous System, Haley Brown

Graduate Theses and Dissertations

The repellant ligand Slit and its Roundabout (Robo) family receptors regulate many aspects of axon guidance in bilaterians, including midline crossing of axons during development of the embryonic CNS. Slit proteins are produced by midline cells and signal through Robo receptors expressed on the surface of axonal growth cones to repel axons from the midline. Disruption of Slit-Robo signaling causes ectopic midline crossing phenotypes in the CNS of a broad range of animals, including insects and vertebrates.

Drosophila Robo1 has a conserved ectodomain structure of five immunoglobulin-like (Ig) domains plus three fibronectin (FN) repeats. By utilizing a genomic rescue construct …

Comparative Meiotic Cytology Among Drosophila Species, Ahmed Folademi Majekodunmi

College of Science and Health Theses and Dissertations

Physical connections established by homologous recombination are normally sufficient to establish proper co-orientation of chromosomes during prometaphase of female meiosis I. Nonexchange chromosomes can still segregate because they are connected by heterochromatic threads, which are thought to connect homologous chromosomes and ensure co-orientation in the absence of a chiasma. In Drosophila, the nonexchange chromosomes (such as the Muller F element, also called the “dot chromosome,” which never undergoes recombination) move out on the spindle during prometaphase I, and can be found positioned between the spindle poles and the exchange chromosomes at the metaphase plate. By metaphase I arrest, these …

Investigating Peroxiredoxins Impact On Amps, Noah Earland

SMU Journal of Undergraduate Research

The Orr-Radyuk lab is interested in understanding the link between aging and genetic influences controlling the cell’s redox state, as determined by enzymes involved in reducing and oxidizing (redox) reactions. They have observed that Drosophila normally exhibit a shift towards a pro-oxidizing cellular environment and spikes in AMP levels, independent of infections, when they reach old age. Additionally, peroxiredoxins (PRXs), a family of thiol-dependent peroxidases, have been shown to impact lifespan, and regulate the same pro-oxidizing shift seen in advanced age. Beyond their peroxidase functions, RXRs can also interact with signaling pathways related to immunity. Previous data showed that PRXs …

Achilles Is A Circadian Clock-Controlled Gene That Regulates The Immune System And Its Rhythmicity In Drosophila, Jiajia Li

Dissertations

Circadian clock is a transcriptional/translational feedback loop that drives the rhythmic expression of downstream mRNAs. Termed “clock-controlled genes,” these molecular outputs of the circadian clock orchestrate cellular, metabolic, and behavioral rhythms. As part of our on-going work to characterize key upstream regulators of circadian mRNA expression, we have identified a novel clock-controlled gene in Drosophila melanogaster, Achilles (Achl), which is rhythmic at the mRNA level in the brain and represses expression of immune response genes, especially anti-microbial peptides in the immune system. Achl knock-down in the brain dramatically elevates expression of crucial immune response genes, including IM1 …

Identification Of Genes That Maintain Behavioral And Structural Plasticity During Sleep Loss, Laurent Seugnet, Stephane Dissel, Matthew S. Thimgan, Lijuan Cao, Paul J. Shaw

Biological Sciences Faculty Research & Creative Works

Although patients with primary insomnia experience sleep disruption, they are able to maintain normal performance on a variety of cognitive tasks. This observation suggests that insomnia may be a condition where predisposing factors simultaneously increase the risk for insomnia and also mitigate against the deleterious consequences of waking. To gain insight into processes that might regulate sleep and buffer neuronal circuits during sleep loss, we manipulated three genes, fat facet (faf), highwire (hiw) and the GABA receptor Resistance to dieldrin (Rdl), that were differentially modulated in a Drosophila model of insomnia. Our results indicate …

Drosophila Studies Support A Role For A Presynaptic Synaptotagmin Mutation In A Human Congenital Myasthenic Syndrome, Mallory C. Shields, Matthew R. Bowers, Mckenzie M. Fulcer, Madelyn K. Bollig, Patrick J. Rock, Bryan R. Sutton, Alysia D. Vrailas-Mortimer, Hanns Lochmüller, Roger G. Whittaker, Rita Horvath, Noreen E. Reist

Biological Sciences: Faculty Scholarship

During chemical transmission, the function of synaptic proteins must be coordinated to efficiently release neurotransmitter. Synaptotagmin 2, the Ca2+ sensor for fast, synchronized neurotransmitter release at the human neuromuscular junction, has recently been implicated in a dominantly inherited congenital myasthenic syndrome associated with a non-progressive motor neuropathy. In one family, a proline residue within the C2B Ca2+-binding pocket of synaptotagmin is replaced by a leucine. The functional significance of this residue has not been investigated previously. Here we show that in silico modeling predicts disruption of the C2B Ca2+-binding pocket, and we examine the in vivo effects of the homologous …

Swing Boat: Inducing And Recording Locomotor Activity In A Drosophila Melanogaster Model Of Alzheimer’S Disease, Johannes Berlandi, Fang Ju Lin, Oliver Ambrée, Dirk Rieger, Werner Paulus, Astrid Jeibmann

Biology

Recent studies indicate that physical activity can slow down progression of neurodegeneration in humans. To date, automated ways to induce activity have been predominantly described in rodent models. To study the impact of activity on behavior and survival in adult Drosophila melanogaster, we aimed to develop a rotating tube device “swing boat” which is capable of monitoring activity and sleep patterns as well as survival rates of flies. For the purpose of a first application, we tested our device on a transgenic fly model of Alzheimer’s disease (AD). Activity of flies was recorded in a climate chamber using the Drosophila …

Novel Effects Of Prefoldin Pathway On Intestinal Homeostasis Via Dietary Restriction In Drosophila Melanogaster, Jesse Simons

Dissertations, Masters Theses, Capstones, and Culminating Projects

The field of medicine research is embroiled in a battle against aging. Particular focus is on the extension of lifespan and health-span. Lifespan duration is affected by many factors, one of which is the maintenance of the intestines of the organism. Homeostasis of the intestines is controlled by the regulation of intestine cell apoptosis and intestine cell proliferation. My research explores the role of two protein subunits found in a complex which may have possible functions in the regulation of these processes. The overall complex is formed from six subunit proteins, some of which are known to assist in other …

Cold Tolerance Of Third-Instar Drosophila Suzukii Larvae., Ruth Jakobs, Banafsheh Ahmadi, Sarah Houben, Tara D Gariepy, Brent J Sinclair

Biology Publications

Drosophila suzukii is an emerging global pest of soft fruit; although it likely overwinters as an adult, larval cold tolerance is important both for determining performance during spring and autumn, and for the development of temperature-based control methods aimed at larvae. We examined the low temperature biology of third instar feeding and wandering larvae in and out of food. We induced phenotypic plasticity of thermal biology by rearing under short days and fluctuating temperatures (5.5-19°C). Rearing under fluctuating temperatures led to much slower development (42.1days egg-adult) compared to control conditions (constant 21.5°C; 15.7days), and yielded larger adults of both sexes. …

Retrotransposons Are The Major Contributors To The Expansion Of The Drosophila Ananassae Muller F Element, William Leung, Sarah C. R. Elgin, Adam Haberman

Biology: Faculty Scholarship

The discordance between genome size and the complexity of eukaryotes can partly be attributed to differences in repeat density. The Muller F element (~5.2 Mb) is the smallest chromosome in Drosophila melanogaster, but it is substantially larger (>18.7 Mb) in Drosophila ananassae. To identify the major contributors to the expansion of the F element and to assess their impact, we improved the genome sequence and annotated the genes in a 1.4 Mb region of the D. ananassae F element, and a 1.7 Mb region from the D element for comparison. We find that transposons (particularly LTR and LINE retrotransposons) …

Octopamine In Sexual Behavior, Ana Isabel Fernandez

Open Access Theses & Dissertations

Octopamine is a biogenic amine neuromodulator present in neuronal and non-neuronal tissues in invertebrates (Roeder, 1999). It modulates numerous physiological processes such as motivation, pheromone response, olfaction, ovulation, learning and memory. Octopamine together with its precursor tyramine have roles restricted only to invertebrates (Roeder, 1999). It is believed that octopamine is the invertebrate homolog of norepinephrine, a catecholamine present in mammals that acts as a neuromodulator in the sympathetic and central nervous systems. Both octopamine and norepinephrine are derived from the same amino acid tyrosine and are monoamine neurotransmitters. The main objective of this study is to understand the role …

The Neuromodulatory Mechanisms That Monoamines Control Simple And Complex Behaviors, Paul Rafael Bermeo Sabandal

Open Access Theses & Dissertations

For my Dissertation, I worked on three projects in the fruit fly Drosophila melanogaster, which is a well-established genetic animal model. The first project (Chapter 1) is to elucidate the neural, cellular and molecular mechanisms underlying behavioral control named response inhibition. In this study, I identified that a particular subset of dopamine neurons, D1 dopamine receptors and the neural substrates crucial for response inhibition. Abnormal response inhibition is associated with the mental disorders including attention deficit hyperactivity disorder (ADHD), autism, schizophrenia, obsessive compulsive disorder, posttraumatic stress disorder and addiction, This study may help enhance our understanding the pathogenesis mechanisms of …

Minibrain And Wings Apart Control Organ Growth And Tissue Patterning Through Downregulation Of Capicua, Liu Yang

Graduate Doctoral Dissertations

The regulation of organ growth is a fundamental aspect of developmental biology. My work uses Drosophila as a model system to understand how the various growth regulators are coordinated. The transcriptional repressor Capicua (Cic) controls tissue patterning and restricts organ growth, and has been recently implicated in several cancers and neurodegenerative diseases. Cic has emerged as a primary sensor of signaling downstream of the receptor tyrosine kinase (RTK)/extracellular signal-regulated kinase (ERK) pathway, but how Cic activity is regulated in different cellular contexts remains poorly understood. In order to identify Cic regulators, I have used affinity purification/mass spectrometry (AP-MS) to study …

Genetic Mechanisms For The Maintenance Of Behavioral Mating Barriers In Drosophila, Kathleen M. Mortland

Arts & Sciences Graduate Student Theses and Dissertations

One of the most successful and diverse systems involved in the maintenance of behavioral barriers between closely related animal species is pheromonal communication. In the fruit fly, contact chemosensation input is especially important during sexual decision-making as it allows for the sensing of sex and species-specific non-volatile cuticular hydrocarbons (CHCs), which function as insect pheromones. However, how pheromonal systems support the maintenance of mating barriers is puzzling since any change in either pheromone ligands or their cognate receptors would carry a fitness cost, which should be eliminated by stabilizing selection. To resolve this evolutionary conundrum I hypothesized that pleiotropic genes …

Endogenous Small Interfering Rna: Insights Into Esirna Biogenesis And Their Precursors, Andrew White Harrington

Dissertations

Rarely in research is the path to an answer straightforward. Initial questions lead to more questions, many times doubling back to allow for greater insight into the original question. For example, discovery of interactions between previously unrelated pathways can lead to breakthroughs with regard to understanding of gene regulation. One such novel interaction and the subsequent discoveries this interaction spurred are discussed herein. Transposons, or “Jumping Genes” are mobile genetic elements found throughout all three major domains of life. Transposons comprise 44% of the human genome and possess the ability to move within the genome. This ability makes them an …

Nucleotide Interdependency In Transcription Factor Binding Sites In The Drosophila Genome, Jacqueline M. Dresch, Rowan G. Zellers, Daniel K. Bork, Robert A. Drewell

Biology

A long-standing objective in modern biology is to characterize the molecular components that drive the development of an organism. At the heart of eukaryotic development lies gene regulation. On the molecular level, much of the research in this field has focused on the binding of transcription factors (TFs) to regulatory regions in the genome known as cis-regulatory modules (CRMs). However, relatively little is known about the sequence-specific binding preferences of many TFs, especially with respect to the possible interdependencies between the nucleotides that make up binding sites. A particular limitation of many existing algorithms that aim to predict binding site …

Reproductive Arrest And Stress Resistance In Winter-Acclimated Drosophila Suzukii., Jantina Toxopeus, Ruth Jakobs, Laura V Ferguson, Tara D Gariepy, Brent J Sinclair

Biology Publications

Overwintering insects must survive the multiple-stress environment of winter, which includes low temperatures, reduced food and water availability, and cold-active pathogens. Many insects overwinter in diapause, a developmental arrest associated with high stress tolerance. Drosophila suzukii (Diptera: Drosophilidae), spotted wing drosophila, is an invasive agricultural pest worldwide. Its ability to overwinter and therefore establish in temperate regions could have severe implications for fruit crop industries. We demonstrate here that laboratory populations of Canadian D. suzukii larvae reared under short-day, low temperature, conditions develop into dark 'winter morph' adults similar to those reported globally from field captures, and observed by us …

Reverse Genetic Screening Of Innexin Gap Junction Proteins In Drosophila Neurons, Shannon P. Fox

Senior Honors Projects, 2010-2019

The reflexive response and perception of pain (nociception) is an evolutionarily conserved process in animals. Pain can be a major health concern and current treatments often prove insufficient, especially in regards to chronic pain. Greater understanding of the molecular processes underlying pain sensation could lead to new and more effective treatments. The aim of this study is to investigate the molecular mechanisms of cold nociception in Drosophila melanogaster. A specific subset of peripheral sensory neurons (Class III dendritic arborization (da) neurons), are implicated in Drosophila larvae’s response to noxious cold.

Previous literature has associated a family of gap junction protein, …

Quantitative Perturbation-Based Analysis Of Gene Expression Predicts Enhancer Activity In Early Drosophila Embryo, Rupinder Sayal, Jacqueline M. Dresch, Irina Pushel, Benjamin R. Taylor, David N. Arnosti

Biology

Enhancers constitute one of the major components of regulatory machinery of metazoans. Although several genome-wide studies have focused on finding and locating enhancers in the genomes, the fundamental principles governing their internal architecture and cis-regulatory grammar remain elusive. Here, we describe an extensive, quantitative perturbation analysis targeting the dorsal-ventral patterning gene regulatory network (GRN) controlled by Drosophila NF-kB homolog Dorsal. To understand transcription factor interactions on enhancers, we employed an ensemble of mathematical models, testing effects of cooperativity, repression, and factor potency. Models trained on the dataset correctly predict activity of evolutionarily divergent regulatory regions, providing insights into spatial relationships …

The Essential Oil Of Lippia Alba Affects Drosophila Behavior And Physiology, Jibin Manimala

Biological Sciences

Lippia alba (LA) is a flowering shrub native to Central and South America. Its essential oil has been used in herbal medicine as an anti-anxiety drug and in aquaculture; it is used to sedate fish during transport (Daniel 2014. Essential oils are derived from plants usually through steam distillation. They are labeled as “essential” because it contains the odor of the plant. Its physiological action is unknown. We use the fruitfly Drosophila melanogaster to further define its behavioral actions and determine its underlying physiological effects. We first tested whether Lippia alba produced had an anesthetic effect on the fruitfly. We …

Population Dynamics Based On Resource Availability & Founding Effects: Live & Computational Models, Samuel Potter, Rebecca M. Krall, Susan Mayo, Diane Johnson, Kimberly J. Zeidler-Watters, Robin L. Cooper

Biology Faculty Publications

With the looming global population crisis, it is more important now than ever that students understand what factors influence population dynamics. We present three learning modules with authentic, student-centered investigations that explore rates of population growth and the importance of resources. These interdisciplinary modules integrate biology, mathematics, and computer-literacy concepts aligned with the Next Generation Science Standards. The activities are appropriate for middle and high school science classes and for introductory college-level biology courses. The modules incorporate experimentation, data collection and analysis, drawing conclusions, and application of studied principles to explore factors affecting population dynamics in fruit flies. The variables …