Cell and Developmental Biology Commons^™

Illuminating Transfer Rna Variants As Genetic Modifiers In Models Of Human Disease, Jeremy T. Lant

Electronic Thesis and Dissertation Repository

Transfer RNAs (tRNAs) physically link the genetic code to an amino acid sequence, by recruiting amino acids to three-nucleotide codons in messenger RNAs. To ensure that the genetic code is translated as intended, tRNAs must be accurately aminoacylated and faithfully recognize codons in the ribosome during protein synthesis. Given the critical function of tRNAs, it has often been assumed that mutations in human tRNA genes would be either lethal to cells or not significantly impair tRNA function. My goal was to rigorously test this assumption in mammalian cell models, prompted by the recent discovery of unprecedented variation in human tRNA …

Genetic Basis Of Hybrid Sterility Between Drosophila Pseudoobscura And D. Persimilis, Alannah J.P. Mattice

Electronic Thesis and Dissertation Repository

Speciation is the underlying process that leads to formation of new species, and therefore is the basis of biodiversity. Genes involved in each stage of speciation, such as those involved in interspecies sterility, remain elusive. Male hybrid sterility and postzygotic isolation between Drosophila pseudoobscura and D. persimilis was examined in this study through backcrossing of female hybrids into each parental line (introgression), selecting for a sterile sperm phenotype, needle-eye sperm. Sperm phenotypes did not separate through backcrossing; instead, males presented with multiple sperm phenotypes. A relationship between the phenotypes observed and the potential genes involved was examined through whole genome …

Mushroom Body-Specific Gene Regulation By The Swi/Snf Chromatin Remodeling Complex, Kevin Cj Nixon

Electronic Thesis and Dissertation Repository

Over the lifetime of an organism, neurons must establish, remodel, and maintain precise connections in order to form neural circuits that are required for proper nervous system functioning. Disruptions in these processes can lead to neurodevelopmental disorders such as intellectual disability (ID) and autism spectrum disorder. Mutations in genes encoding subunits of the SWI/SNF chromatin remodeling complex have been implicated in ID, yet the role of this complex in neurons is poorly understood. In this project, I established cell-type specific methods to examine the effect of SWI/SNF subunit knockdowns on gene transcription and chromatin structure in the memory-forming neurons of …

Characterization Of Plant-Spider Mite Interactions And Establishment Of Tools For Spider Mite Functional Genetic Studies, Nicolas Bensoussan

Electronic Thesis and Dissertation Repository

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most polyphagous herbivores feeding on cell contents of over 1100 plant species including more than 150 crops. However, despite its important pest status and a growing understanding of the molecular basis of its interactions with plant hosts, knowledge of the way mites interface with the plant while feeding and the plant damage directly inflicted by mites is lacking. Likewise, while the use of the reverse genetic tools in plants facilitated our understanding of the establishment of defense mechanisms against spider mite herbivory, such tools are lacking for …

Characterization Of Acaricide Resistance, Plant-Mediated Rnai Against Two-Spotted Spider Mites (Tetranychus Urticae Koch), And Assessing Off- And Non-Target Effects, Hooman Hosseinzadeh Namin

Electronic Thesis and Dissertation Repository

The two-spotted spider mite (TSSM), Tetranychus urticae (Koch), is one of the most damaging agricultural pests in the world. It feeds on over 150 crops, causing considerable yield losses in greenhouses and agricultural fields. Currently, using synthetic acaricides is the main method to control TSSM. However, it can develop resistance to acaricides with repeated exposure, and typically resistance can occur within two to four years. To understand the underlying mechanisms of spider mite adaptation to acaricides is an essential part of resistance management strategy. The resistance ratio of the pyridaben-selected strain compared with the pre-selection strain was estimated at greater …

Functional Characteristics Of Four Novel Lone Atrial Fibrillation-Linked Connexin40 Mutants, Mahmoud Noureldin

Electronic Thesis and Dissertation Repository

Atrial fibrillation (AF) is the most common form of cardiac arrhythmia. Recently, four novel heterozygous Cx40 mutations, K107R, L223M, Q236H, and I257L were identified in 4 of 310 unrelated AF patients. To study possible alterations associated with these mutants, we studied their localization and function using gap junction (GJ)-deficient model cells. Cell pairs expressing Q236H alone or together with wildtype Cx43 showed a significantly lower coupling conductance. Impaired GJ function and dominant negative action on Cx43 of this mutant are consistent with previous findings on the majority of AF-linked Cx40 mutants. The remaining three novel AF-linked mutants did not show …

Nucleoporin-Mediated Regulation Of The Kcnq1ot1 Imprinted Domain, Saqib Sachani

Electronic Thesis and Dissertation Repository

Genomic imprinting is an epigenetic phenomenon that restricts gene expression to one parental allele while the other copy is silent. How this duality is regulated is not fully understood. Using the Kcnq1ot1 imprinted domain as a model, previous work in the laboratory identified nucleoporin 107 as a candidate regulator of imprinted domain regulation. Within the Kcnq1ot1 domain resides the imprinting control region, the paternally expressed Kcnq1ot1 (Kcnq1 opposite transcript 1) noncoding RNA, nine maternal-expressed protein-coding genes, as well as genes that escape imprint regulation. On the maternal allele, the Kcnq1ot1 imprinting control region is methylated, silencing the embedded Kcnq1ot1 …

The Atp2c2 Gene As Transcribed From A Novel Transcriptional Start Site In Pancreatic Acinar Cells, Caitlin M. Sullivan

Electronic Thesis and Dissertation Repository

Strict regulation of cytosolic Ca²⁺ is essential to regulated exocytosis and proper pancreatic acinar cell function, controlled in part by pumps that shuttle Ca²⁺ out of the cytosol. Our laboratory identified a novel isoform of Secretory Ca²⁺ ATPase 2 (SPCA2) containing only the carboxy terminus. Pancreatic SPCA2, is an approximately 17-20 kDa, protein encoded by the Atp2c2 gene and is completely absent in Mist1^-/- acini.. The focus of this thesis was to understand transcriptional regulation of Atp2c2 in the pancreas. Pancreatic Atp2c2 appears to be transcribed from an alternative transcriptional start site (TSS) and is regulated …

Uncovering Dual Roles For Perk Signaling During Experimentally Induced Pancreatitis, Elena Fazio

Electronic Thesis and Dissertation Repository

Pancreatitis is characterized by inappropriate activation of digestive enzyme

precursors, or zymogens, local and systemic inflammation, dysregulation of

cellular calcium (Ca2+), and induction of the unfolded protein response (UPR).

The UPR consists of three distinct pathways all of which are activated during

pancreatitis. However, the molecular roles of each remain unclear. The

protein kinase RNA (PKR)-like ER kinase (PERK) pathway reduces general

protein translation by phosphorylating eIF2!, and is activated within minutes

of initiating pancreatic damage. Microarray analysis carried out by our lab

revealed robust upregulation of the PERK pathways members Activating

Transcription Factor (ATF) 3 and stanniocalcin (STC) 2. …

The Intracellular Behaviour Of Burkholderia Cenocepacia In Murine Macrophages, Jennifer S. Tolman

Electronic Thesis and Dissertation Repository

Burkholderia cenocepacia is an opportunistic pathogen causing life-threatening infections in cystic fibrosis and other immunocompromised patients. The bacterium survives within macrophages by interfering with typical endocytic trafficking, resulting in delayed maturation of a B. cenocepacia-containing phagosome. We hypothesize that B. cenocepacia alters gene expression after internalization by macrophages, inducing genes involved in intracellular survival and host adaptation. Furthermore, we hypothesize that specialized bacterial secretion systems are involved in the interactions between intracellular bacteria and macrophages. In this work, we characterize later-stage infection of macrophages by B. cenocepacia, showing replication within an acidified endosomal compartment suggestive of a phagolysosome. …

Brassinosteroid-Mediated Stress Tolerance In Arabidopsis Thaliana, Tawhidur Rahman

Electronic Thesis and Dissertation Repository

Brassinosteroids (BRs) are a group of steroidal plant hormones that are essential for proper plant development and also promote stress tolerance. Without BRs, plants are dwarfs and infertile. To understand the molecular mechanisms underlying BR-mediated stress tolerance, global gene expression analysis of untreated and 24-epibrassinolide (EBR)-treated Arabidopsis thaliana seedlings under non-stress and heat stress (HS) conditions was carried out. Microarray data analysis indicated that stress-related genes were predominant within the EBR up-regulated gene data set. Furthermore, several of these genes were abscisic acid (ABA) and jasmonic acid (JA) related. Measurements of endogenous hormones showed significant increases in the levels ABA …