Genetics and Genomics Commons^™

Identification Of Lead-Sensitive Expression And Splicing Quantitative Trait Loci In Drosophila Melanogaster By Analysis Of Rna-Seq Data, Wen Qu

Wayne State University Dissertations

Lead exposure has long been one of the most important topics in global public health since it is a potent developmental neurotoxin. Here, we conducted an expression QTL (eQTLs) analysis, which is genome-wide association analysis of genetic variants with differential gene expression, in the male heads of 79 Drosophila melanogaster recombinant inbred lines originally from eight parental strains in the presence or absence of developmental exposure to 250 µM lead acetate. The aim was to study the effects of lead exposure on gene expression and identify the lead-responsive genes. After detecting 1,536 cis-eQTLs and 952 trans-eQTLs (1000 permutation threshold at …

Drosophila Let-7 Microrna Is Required For Remodeling Of The Neuromusculature During Metamorphosis, Nicholas S. Sokol, Peizhang Xu, Yuh-Nung Jan, Victor R. Ambros

Victor R. Ambros

The Drosophila let-7-Complex (let-7-C) is a polycistronic locus encoding three ancient microRNAs: let-7, miR-100, and fly lin-4 (miR-125). We find that the let-7-C locus is principally expressed in the pupal and adult neuromusculature. let-7-C knockout flies appear normal externally but display defects in adult behaviors (e.g., flight, motility, and fertility) as well as clear juvenile features in their neuromusculature. We find that the function of let-7-C to ensure the appropriate remodeling of the abdominal neuromusculature during the larval-to-adult transition is carried out predominantly by let-7 alone. This heterochronic role of let-7 is likely just one of the ways in which …

The Effect Of Serrate Transmembrane Domain Substitution On Notch Signaling, James Z. Curlin

Senior Theses and Projects

The Notch signaling pathway is a crucial means by which organisms differentiate cells during development. Notch is regulated primarily through the interaction of a Notch receptor protein and a ligand protein, in two specific ways. Cis-inhibition occurs when both a ligand and receptor are present on the same cellular membrane. This results in the cis-ligand binding to the receptor and preventing the ligand on an adjacent cell from binding and activating the receptor. Alternatively, trans-activation occurs when the ligand and receptor are on adjacent cells, and results in the activation of the Notch pathway. Both the receptor …

Investigating Notch Signaling And Sequential Segmentation In The Fairy Shrimp, Thamnocephalus Platyurus, Sara Izzat Khalil

Senior Theses and Projects

Segmentation is a key feature of arthropod diversity and evolution. In the standard model for arthropod development, Drosophila melanogaster, segments develop simultaneously by a progressive subdivision of the embryo. By contrast, most arthropods add segments sequentially from a posterior region called the growth zone and in a manner similar to vertebrates.

Recent work, mainly focused on insects, suggests that Notch signaling might play a role in arthropods that segment sequentially. These studies document a potential regulatory similarity between sequentially segmenting arthropods and vertebrates. In vertebrates, somite formation involves a molecular oscillator that functions as a pacemaker, driving periodic expression …

Drosophila Cyclin J And The Somatic Pirna Pathway Cooperate To Regulate Germline Stem Cells, Paul Michael Albosta

Wayne State University Dissertations

Cyclin J (CycJ) is a highly conserved cyclin that is uniquely expressed specifically in ovaries in Drosophila. Deletion of the genomic region containing CycJ and adjacent genes resulted in a genetic interaction with neighboring piRNA pathway gene, armitage (armi). Here I assessed oogenesis in CycJ null in the presence or absence of mutations in armi or other piRNA pathway genes. Although CycJ null flies had decreased egg laying and hatching rates, ovaries appeared normal indicating that CycJ is dispensable for oogenesis under normal conditions. Further double mutant analysis of CycJ and neighbor armi, as well as two other piRNA pathway …

A Protective Role Of Autophagy In A Drosophila Model Of Friedreich's Ataxia (Frda), Luan Wang

Wayne State University Dissertations

Friedreich’s ataxia (FRDA) is an inherited autosomal recessive neurodegenerative disease. It affects 1 in every 50,000 people in central Europe and North America. FRDA is caused by deficiency of Frataxin, an essential mitochondrial iron chaperone protein, and the associated oxidative stress damages. Autophagy, a housekeeping process responsible for the bulk degradation and turnover of long half-life proteins and organelles, is featured by the formation of double-membrane vacuoles and lysosomal degradation. Previous researches indicate that Danon’s disease, the inherited neural disorder disease that shares similar symptoms with FRDA, is due to the malfunction of autophagy. Based on this, we raise the …

Effect Of Altered Cellular Redox Environment On Oncogenic Activity Of The Drosophila Prl Protein, Frances Welsh

Summer Research

Aberrant expression of members of the phosphatase of regenerating liver (PRL) family has been implicated as a key factor in the progression of several forms of human cancers. However, despite a wide range of studies supporting the role of the enzyme PRL as an oncogene, it has also been identified as a growth suppressor when tested under different conditions. One proposed explanation for this change in function is that redox regulation controls the accessibility of the active site of PRLs, which is necessary for oncogenic output. In this study, cellular redox environment was altered in vivo using Drosophila melanogaster, …

Suppression Of Neurodegenerative Symptoms Via Suppressor Of Levy Mutation In Drosophila Melanogaster, William Kaputa

Forensic Science Theses

Mutation of the levy gene on chromosome 2 of Drosophila melanogaster has previously been shown to cause temperature-induced paralysis and neurodegeneration. The Suppressor of levy mutation, Su(levy), also on chromosome 2, modulates the effects of the levy mutation and partly rescues the wild-type phenotype. The goal of this research was to determine if Su(levy) mutation alleviates the effects of neurodegeneration caused by mutations associated with Alzheimer’s and Parkinson’s diseases in humans. The mutant genes used were hLRRK2, α-Synuclein, DJ1-α, Pink, Parkin, and Aβ-42. To determine this, flies carrying the above-mentioned mutant genes were …

Cloning And Expression Analysis Of Drosophila Extracellular Cu Zn Superoxide Dismutase, Michael J. Blackney, Rebecca Cox, David Shepherd, Joel D. Parker

Joel D Parker

In the present study, we cloned and sequenced the mRNAs of the Sod3 [extracellular Cu Zn SOD (superoxide dismutase)] gene in Drosophila and identified two mRNA products formed by alternative splicing. These products code for a long and short protein derived from the four transcripts found in global expression studies (Flybase numbers Dmel\CG9027, FBgn0033631). Both mRNA process variants contain an extracellular signalling sequence, a region of high homology to the Sod1 (cytoplasmic Cu Zn SOD) including a conserved AUG start, with the longer form also containing a hydrophobic tail. The two fully processed transcripts are homologous to Caenorhabditis elegans Sod3 …

Rejuvenation Of Meiotic Cohesion In Oocytes During Prophase I Is Required For Chiasma Maintenance And Accurate Chromosome Segregation, Katherine A. Weng, Charlotte A. Jeffreys, Sharon E. Bickel

Dartmouth Scholarship

Chromosome segregation errors in human oocytes are the leading cause of birth defects, and the risk of aneuploid pregnancy increases dramatically as women age. Accurate segregation demands that sister chromatid cohesion remain intact for decades in human oocytes, and gradual loss of the original cohesive linkages established in fetal oocytes is proposed to be a major cause of age-dependent segregation errors. Here we demonstrate that maintenance of meiotic cohesion in Drosophila oocytes during prophase I requires an active rejuvenation program, and provide mechanistic insight into the molecular events that underlie rejuvenation. Gal4/UAS inducible knockdown of the cohesion establishment factor Eco …

Sex And Heterochromatin: An Investigation Of Sexual Dimorphism In Drosophila Melanogaster, Manasi S. Apte

Wayne State University Dissertations

Over 30% of Drosophila genome is assembled into heterochromatin. Heterochromatin is relatively gene poor, transcriptionally less active and remains condensed during interphase. Previous studies established that roX RNA and some of the Male Specific Lethal (MSL) proteins, all components of the dosage compensation complex, are required for full expression of autosomal heterochromatic genes in male flies but not in females. This was surprising since heterochromatin is generally not thought to be sexually dimorphic. The genetic basis for the regulation of sex-specific heterochromatin was completely unknown.

To determine if roX RNAs localize directly at the heterochromatic regions that they regulate, I …

The Jak/Stat Pathway Is Reutilized In Drosophila Spermatogenesis, Lingfeng Tang

Theses and Dissertations--Biology

In the Drosophila testis, sperm are derived from germline stem cells (GSCs) which undergo a stereotyped pattern of divisions and differentiation. The somatic cells at the tip of the testis form the hub, which is the niche for both the somatic cyst stem cells (CySCs) and GSCs. The hub expresses Upd, a ligand for the JAK/STAT pathway that has roles in the maintenance of CySCs and GSCs. Male mutants of upd3, another ligand of the JAK/STAT pathway, become sterile much earlier than the wild-type, leading to the hypothesis that similar to upd, upd3 also promotes the self-renewal of …

Multi-Species Gene Networks And Drosophila Ethanol Sedation, Arnavaz Kollah

Theses and Dissertations

Alcohol use disorders (AUDs) are major health issues with few known genetic explanations. This project used the fruit fly (Drosophila melanogaster) model to identify genes and gene networks that influence alcohol intoxication, a phenotype related to alcohol abuse in humans. We used bioinformatic tools to build gene networks based on 24 published Drosophila ethanol-responsive genes with human orthologs. We then assessed the role of these networks in ethanol sedation by testing two of the networks seeded on IP3K2, a gene that regulates calcium signaling, and CG14630, a gene involved in carnitine biosynthesis. We knocked down several genes in each of …

An Automatic Framework For Embryonic Localization Using Edges In A Scale Space, Zachary Bessinger

Masters Theses & Specialist Projects

Localization of Drosophila embryos in images is a fundamental step in an automatic computational system for the exploration of gene-gene interaction on Drosophila. Contour extraction of embryonic images is challenging due to many variations in embryonic images. In the thesis work, we develop a localization framework based on the analysis of connected components of edge pixels in a scale space. We propose criteria to select optimal scales for embryonic localization. Furthermore, we propose a scale mapping strategy to compress the range of a scale space in order to improve the efficiency of the localization framework. The effectiveness of the proposed …

Control Of Neuroendocrine Cell Physiology By A Single Transcription Factor, Drosophila Basic Helix Loop Helix Regulator Dimmed, Tarik Hadzic

All Theses and Dissertations (ETDs)

Neuroendocrine cells feature a large capacity for the processing, accumulation and regulated release of bioactive peptides and peptide hormones. The ultrastructural correlate of this regulated secretory pathway is a specialized organelle, called a dense core vesicle: DCV). DCVs are typically larger than conventional, small synaptic vesicles. Past work has identified intrinsic DCV proteins: non-cargo proteins, like the processing enzyme, carboxypeptidase) or ancillary ones that play a role in DCV trafficking and exocytosis: like CAPS, the Ca2+-dependent activator protein for secretion). Currently, there is a lack of understanding of the developmental and physiological mechanisms that permit neurosecretory cells to coordinate and …

The Drosophila Interactions Database: Integrating The Interactome And Transcriptome, Thilakam Murali

Wayne State University Dissertations

In this thesis I describe the integration of heterogeneous interaction data for Drosophila into DroID, the Drosophilainteractions database, making it a one-stop public resource for interaction data. I have also made it possible to filter the interaction data using gene expression data to generate context-relevant networks making DroID a one-of-a kind resource for biologists. In the two years since the upgraded DroID has been available, several studies have used the heterogeneous interaction data in DroID to advance our understanding of Drosophila biology thus validating the need for such a resource for biologists. In addition to this, I have identified …

Examining The Functional Role Of Dprl-1 In Drosophila Melanogaster, John Valenzuela

Summer Research

The Phosphatase of Regenerating Liver (PRL) family of proteins control cell growth, motility and proliferation. They have been shown to elevate the levels of these functions, leading to an increase in cancer metastasis (“malignancy”), when they are overexpressed. The goal of this experiment is to knockout PRL gene expression to examine the general function of PRL proteins. Drosophila melanogaster have only one copy of the PRL gene (dPRL-1), as opposed to humans and other mammals, which have 3. Thus, using P-element imprecise excision to create mutant strains either fully lacking or with decreased function of the dPRL-1 protein, …

A Genetic, Transgenic, And Transcriptomic Analysis Of Larval Salivary Gland Physiology In Drosophila Melanogaster, Elana A. Paladino

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cholesterol is the precursor to a unique class of lipophilic signaling molecules called steroid hormones that initiate the development of sexual characteristics, reactions to stress, and maintenance of metabolism, among many other functions. Although much progress has been made in understanding the function of these signaling hormones, we do not fully understand how a single steroid can cause many distinct, tissue-specific responses. Drosophila melanogaster is an effective model for understanding steroid hormone action because of its simplicity. The steroid molting hormone 20-hydroxyecdysone (hereafter, 20E) is the primary active steroid in Drosophila and mediates not only larval molts and the emergence …

Roles Of The Drosophila Sk Channel (Dsk) In Courtship Memory, Ahmad N. Abou Tayoun, Claudio Pikielny, Patrick J. Dolph

Dartmouth Scholarship

A role for SK channels in synaptic plasticity has been very well-characterized. However, in the absence of simple genetic animal models, their role in behavioral memory remains elusive. Here, we take advantage of Drosophila melanogaster with its single SK gene (dSK) and well-established courtship memory assay to investigate the contribution of this channel to memory. Using two independent dSK alleles, a null mutation and a dominant negative subunit, we show that while dSK negatively regulates the acquisition of short-term memory 30 min after a short training session, it is required for normal long-term memory 24 h after extended …

A Systematic Genetic Screen To Dissect The Microrna Pathway In Drosophila, Sigal Pressman, Catherine A. Reinke, Xiaohong Wang, Richard W. Carthew

Faculty Publications

A central goal of microRNA biology is to elucidate the genetic program of miRNA function and regulation. However, relatively few of the effectors that execute miRNA repression have been identified. Because such genes may function in many developmental processes, mutations in them are expected to be pleiotropic and thus are discarded in most standard genetic screens. Here, we describe a systematic screen designed to identify all Drosophila genes in ~40% of the genome that function in the miRNA pathway. To identify potentially pleiotropic genes, the screen analyzed clones of homozygous mutant cells in heterozygous animals. We identified 45 mutations representing …

Evolution Of Starvation Resistance In Drosophila Melanogaster: Measurement Of Direct And Correlated Responses To Artificial Selection, Tiffany E. Schwasinger-Schmidt, Stephen D. Kachman, Lawrence G. Harshman

Lawrence G. Harshman Publications

Laboratory selection for resistance to starvation has been conducted under relatively controlled conditions to investigate direct and correlated responses to artificial selection. With regard to starvation resistance, there are three physiological routes by which the trait can evolve: resource accumulation, energy conservation and starvation tolerance. A majority of energetic compounds and macromolecules including triglycerides, trehalose and other sugars, and soluble protein increased in abundance as a result of selection. Movement was additionally investigated with selected males moving less than control males and selected females exhibiting a similar response to selection. Results obtained from this study supported two of the possible …

Erect Wing Facilitates Context-Dependent Wnt/Wingless Signaling By Recruiting The Cell-Specific Armadillo-Tcf Adaptor Earthbound To Chromatin, Nan Xin, Hassina Benchabane, Ai Tian, Kerrie Nguyen, Lindsay Klofas, Yashi Ahmed

Dartmouth Scholarship

During metazoan development, the Wnt/Wingless signal transduction pathway is activated repetitively to direct cell proliferation, fate specification, differentiation and apoptosis. Distinct outcomes are elicited by Wnt stimulation in different cellular contexts; however, mechanisms that confer context specificity to Wnt signaling responses remain largely unknown. Starting with an unbiased forward genetic screen in Drosophila, we recently uncovered a novel mechanism by which the cell-specific co-factor Earthbound 1 (Ebd1), and its human homolog jerky, promote interaction between the Wnt pathway transcriptional co-activators B-catenin/Armadillo and TCF to facilitate context-dependent Wnt signaling responses. Here, through the same genetic screen, we find an unanticipated requirement …

Cell Polarity Regulates Organ Growth Through The Hippo Pathway, Chiao-Lin Chen

Dissertations & Theses (Open Access)

Defects in apical-basal cell polarity and abnormal expression of cell polarity determinants are linked to human cancer. Loss of polarity is highly correlated with malignancy. In Drosophila, perturbation of apical-basal polarity, including overexpressing the apical determinant Crumbs, can lead to uncontrolled tissue growth. Cells mutant for the basolateral determinant scribble overproliferate and can form neoplastic tumors. Interestingly, scribble mutant clones that arise in wild-type tissues are eliminated and therefore do not manifest their tumorigenic potential. However, the mechanisms by which cell polarity coordinates with growth control pathways in developing organs to achieve appropriate organ size remain obscure.

To investigate …

Characterization Of Cis-Regulatory Elements Controlling Repo Transcription In Drosophila Melanogaster, Robert Johnson

Electronic Theses and Dissertations

The glial cells missing (gcm) gene has been identified as a "master regulator" of glial cell fate in the fruit fly Drosophila . However, the gcm gene is also expressed in and required for the development of larval macrophages and tendon cells, and lamina neurons in the adult CNS. Thus, the Gcm protein activates the transcription of different sets of genes in different developmental contexts. How the Gcm protein regulates these different outcomes is not known. My long-term goal is to identify proteins that collaborate with Gcm to promote the transcriptional activation of Gcm target genes specifically in glial cells, …

Genetic Analysis Of The Function Of The Drosophila Doublesex-Related Factor Dmrt93b, Diana O'Day

Dissertations & Theses (Open Access)

DMRT (Doublesex and Mab-3 related transcription factor) proteins generally associated with sexual differentiation in many organisms share a common DNA binding domain and are often expressed in reproductive tissues. Aside from doublesex, which is a central factor in the regulation of sex determination, Drosophila possesses three different dmrt genes that are of unknown function. Because the association with sexual differentiation and reproduction is not universal and some DMRT proteins have been found to play other developmental roles we chose to further characterize one of these Drosophila genes. We carried out genetic analysis of dmrt93B, which was previously found to be …

Damage-Induced Inflammation And Nociceptive Hypersensitivity In Drosophila Larvae, Daniel T. Babcock

Dissertations & Theses (Open Access)

Mounting an effective response to tissue damage requires a concerted effort from a number of systems, including both the immune and nervous systems. Immune-responsive blood cells fight infection and clear debris from damaged tissues, and specialized pain receptors become hypersensitive to promote behavior that protects the damaged area while it heals. To uncover the cellular and molecular mechanisms underlying these processes, we have developed a genetically tractable invertebrate model of damage-induced inflammation and pain hypersensitivity using Drosophila larvae.

To study wound-induced inflammation, we generated transgenic larvae with fluorescent epidermal cells and blood cells (hemocytes). Using live imaging, we monitored the …

The Role Of Ecdysone Signaling In Fat-Body Tissue Remodeling And Pupal Metabolism, Nichole Dinell Bond

UNLV Theses, Dissertations, Professional Papers, and Capstones

Holometabolous insects undergo an astonishing transition during their development. During metamorphosis, the larva dramatically changes form and becomes an adult fly. During this process obsolete larval tissues must be eliminated, while tissues required for further development are retained and often remodeled to meet the needs of the adult fly. Tissue remodeling is characterized by morphological changes of the cells in a tissue mass. In many cases, remodeling is characterized by dissociation of the tissue mass, releasing cells to move freely around the body cavity. This process is also common in wound healing and is a key feature of human disease …

The Differential Roles Of D-Pax2 Variants In Regulating Drosophila Eye And Bristle Development, Colin J. O’Shea

Honors Theses

The ability to appropriately interact with the environment is crucial to an organism’s survival. The establishment of functional sensory systems, such as the bristles and eyes in Drosophila, is a critical event during the development of the organism. The transcription factor D Pax2 is involved in the differentiation of the shaft and glial cells in the developing bristle (Kavaler et al., Dev, 126:2261-2272, 1999) and of the cone and primary pigment cells in the developing eye (Fu and Noll, Genes Dev, 11:389-405, 1997). How D-Pax2 contributes to distinct differentiative pathways in different cell types is not known. Recent work by …

Evolution Acts On Enhancer Organization To Fine-Tune Gradient Threshold Readouts, Justin Crocker, Yoichiro Tamori, Albert Erives

Dartmouth Scholarship

The elucidation of principles governing evolution of gene regulatory sequence is critical to the study of metazoan diversification. We are therefore exploring the structure and organizational constraints of regulatory sequences by studying functionally equivalent cis-regulatory modules (CRMs) that have been evolving in parallel across several loci. Such an independent dataset allows a multi-locus study that is not hampered by nonfunctional or constrained homology. The neurogenic ectoderm enhancers (NEEs) of Drosophila melanogaster are one such class of coordinately regulated CRMs. The NEEs share a common organization of binding sites and as a set would be useful to study the relationship …

Adenomatous Polyposis Coli Is Present Near The Minimal Level Required For Accurate Graded Responses To The Wingless Morphogen, Hassina Benchabane, Edward G. Hughes, Carter M. Takacs, Jason R. Baird, Yashi Ahmed

Dartmouth Scholarship

The mechanisms by which the Wingless (Wg) morphogen modulates the activity of the transcriptional activator Armadillo (Arm) to elicit precise, concentration-dependent cellular responses remain uncertain. Arm is targeted for proteolysis by the Axin/Adenomatous polyposis coli (Apc1 and Apc2)/Zeste-white 3 destruction complex, and Wg-dependent inactivation of destruction complex activity is crucial to trigger Arm signaling. In the prevailing model for Wg transduction, only Axin levels limit destruction complex activity, whereas Apc is present in vast excess. To test this model, we reduced Apc activity to different degrees, and analyzed the effects on three concentration-dependent responses to Arm signaling that specify distinct …