Life Sciences Commons^™

Determining The Effects Of Mistranslating Transfer Rna Variants On Drosophila Melanogaster, Joshua R. Isaacson

Electronic Thesis and Dissertation Repository

Transfer RNAs (tRNAs) play a central role in translation as adaptor molecules between mRNA and protein. Variant tRNAs can cause the misincorporation of an amino acid into a growing polypeptide. Mistranslating tRNA variants are surprisingly common in humans but the effects of mistranslating tRNA variants on eukaryotic biology are poorly understood. My thesis aimed to create a model of tRNA-induced mistranslation using the fruit fly Drosophila melanogaster and characterize the effects of mistranslating tRNA variants on eukaryotic biology.

I first integrated a gene encoding a serine tRNA variant that induced proline-to-serine (P>S) mistranslation into the fly genome. Proteins isolated …

Advances In Phaeodactylum Tricornutum Nuclear Engineering, Mark Pampuch

Electronic Thesis and Dissertation Repository

The marine diatom Phaeodactylum tricornutum has the potential to become an excellent platform for the sustainable production of valuable compounds and pharmaceuticals, but currently large-scale engineering of this organism remains a challenge due factors like inefficient genetic transformation protocols and a lack of accurate genomic data. This thesis addresses these two bottlenecks by (i) optimizing an electroporation protocol to P. tricornutum and (ii) remapping genomic data from a scaffolded genome assembly to a telomere-to-telomere genome assembly. An optimized transformation protocol was developed that could consistently transform blunt-ended and DNA with overhangs and yielded up to 1000+ colony forming units per …

Elucidating The Neural Circuitry Underlying Social Spacing In Drosophila Melanogaster Through The Lens Of Neuroligin 3, Abigail T. Bechard

Electronic Thesis and Dissertation Repository

Social interactions among animals can be complex, and abnormal social behaviours may result in negative fitness consequences for both the individual displaying them, and the entire group. To understand the neural basis of complex social behaviour, we can study simpler behaviours that precede and mediate them. Social spacing, the typical distance between individuals in a group, is an easily quantifiable behaviour in Drosophila melanogaster. Here, I investigated the neural circuitry underlying social spacing through the lens of Autism-candidate gene neuroligin 3. Based on the Nlg3 enrichment pattern in adult fly brains, I hypothesized that nlg3-expressing neurons, along …

Mouse Genotyping Array-Based Analysis Of Variation At Single Nucleotide Polymorphic Loci In The Context Of Macro- And Micro-Environments, Freda Qi

Electronic Thesis and Dissertation Repository

Comparing genetic variation between populations can provide insight into selective pressures in the environment. The Mouse Diversity Genotyping Array (MDGA) is a low-cost, high-throughput tool developed to capture and analyze variation at single nucleotide polymorphic (SNP) loci in inbred mouse strains. However, its ability to assess genetic variation in non-inbred mice and associate SNPs with the environment has not been extensively studied. First, SNPs between laboratory inbred and wild-caught mice were compared. No SNPs were associated with either macroenvironment. Instead, SNPs reflected genealogy and inbreeding strategies, consistent with the MDGA’s intended use. Second, mutations at SNP loci were compared between …

Selection Pressure On Surface Exposed Virus Proteins, Sareh Bagherichimeh

Electronic Thesis and Dissertation Repository

Viral infection requires the interaction between virus surface-exposed (SE) proteins and host cell receptors. This can result in an “arms race” that is assumed to drive accelerated rates of evolution, and some well known examples of diversifying selection involve surface pro- teins (HIV-1 env, influenza hemagglutinin). We conducted a systematic analysis to determine whether this is truly a distinctive feature of SE virus proteins, in comparison to non-SE proteins encoded by the same genomes.

We obtained reference and all neighbour genomes of 52 human viruses from the NCBI Viral Genomes database. The coding sequences (CDS) of each genome extracted by …

Towards More Complete Metagenomic Analyses Through Circularized Genomes And Conjugative Elements, Benjamin R. Joris

Electronic Thesis and Dissertation Repository

Advancements in sequencing technologies have revolutionized biological sciences and led to the emergence of a number of fields of research. One such field of research is metagenomics, which is the study of the genomic content of complex communities of bacteria. The goal of this thesis was to contribute computational methodology that can maximize the data generated in these studies and to apply these protocols human and environmental metagenomic samples.

Standard metagenomic analyses include a step for binning of assembled contigs, which has previously been shown to exclude mobile genetic elements, and I demonstrated that this phenomenon extends to all conjugative …

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 …

The Genetics Of Pain: An Exploration Of Gene-By-Environment Interactions And Their Effects On Pain, Mohamad F. Fakhereddin

Electronic Thesis and Dissertation Repository

The findings presented in this dissertation are part of the bigger SYMBIOME project which aims to use the biopsychosocial model of pain to develop a prognostic clinical phenotype for people that experience musculoskeletal (MSK) trauma. Chapter 2 presents an exploratory analysis to assess the relationships between genetic polymorphisms and pain severity and interference. Early childhood trauma was also explored as a moderator between genetic polymorphisms and pain outcomes. For pain severity, major allele carriers (A/A and G/A) of FKBP5 rs9394314 reported significantly higher scores than minor allele carriers (G/G). Further, major allele carriers who had at least one adverse childhood …

Establishment Of A Pesticide Resistance Monitoring Tool For The Two-Spotted Spider Mite, Tetranychus Urticae, Hanna Varonina

Electronic Thesis and Dissertation Repository

Two-spotted spider mite (TSSM), or Tetranychus urticae (Koch), is a major agriculture pest known for its rapid development of resistance to pesticides. The analysis of spider mites’ pesticide resistance demonstrated that resistance patterns and frequencies vary between T. urticae strains collected from different geographic locations and host plants. This research aims at characterization of pesticide resistance patterns in mite populations present in greenhouses in the Southwestern Ontario by identifying genetic and metabolic markers of their pesticide resistance. The establishment of these markers lays the basis for development of a pesticide resistance diagnostic tool that will enable prediction of population resistance …

Functional Characterization Of Arogenate Dehydratase Isoforms In Soybean, Ramtin Sirjani

Electronic Thesis and Dissertation Repository

Phenylalanine flux is partitioned between phenylpropanoid and protein synthesis. The mechanisms behind the metabolic channeling of phenylalanine are largely unknown. Arogenate dehydratase (ADT) enzymes, which catalyze the last and rate-limiting step in the synthesis of phenylalanine in plants, have been shown to interact with the isoflavonoid metabolon in the cytosol. Cytosolic phenylalanine, however, can only be synthesized through prephenate dehydratase (PDT) activity. In this study, putative soybean ADTs (GmADTs) were characterized for their ADT and PDT activity. This was done using complementation assays with two different knockout yeast strains, aro8aro9 and pha2, which lack prephenate aminotransferase and PDT activity, …

Evaluation Of Two Mouse Models Of High Genetic Variation For Suitability To Test A Heterozygote Instability Hypothesis, Hailie Pavanel

Electronic Thesis and Dissertation Repository

Characterization of genetic variation underlying complex phenotypes is incomplete yet critical to understanding mutational mechanisms and phenotypes. Heterozygote Instability (HI) is a new, poorly understood source of mutations needing models for mechanistic study. Two models ideal for characterizing HI-associated mutational mechanisms are outbred mice and mouse basal cell carcinoma (BCC). Both have discontinuous landscapes of heterozygosity essential to assess HI-induced mutations. Here, heterozygosity and copy number variants (CNVs) in two outbred mouse stocks are characterized with 1690, and 3935 autosomal CNVs detected. A positive correlation exists between chromosomal heterozygosity and CNV occurrence (R² = 0.14 and 0.09), and 41 …

Genetic Approaches For The Study Of Complex Human Diseases, Julieta Lazarte

Electronic Thesis and Dissertation Repository

The field of human genetics has evolved from its initial narrow focus on single-gene Mendelian disorders, which largely affect children, to our current understanding that for most diseases there is continuum of rare to common variants which can exert a range of phenotypic effects. Despite advances in sequencing capabilities and our overall understanding of diseases, there remains a large proportion of heritability unexplained. Through the use of next-generation sequencing technologies and DNA microarray, I have explored a spectrum of genetic variations from rare, single and structural variants to common variants in individuals with i) “lone” atrial fibrillation; ii) familial hypercholesterolemia; …

The Role Of Gsk3 Alpha And Beta In Embryonic Craniofacial Development, Harman Jassar

Electronic Thesis and Dissertation Repository

Background: The GSK-3 genes (Gsk3a and Gsk3b) have been known to affect many cellular processes and signaling pathways some of which are implicated in the growth and development of the craniofacial skeleton.

Aim: The purpose of this study was to assess the effect of chondrocyte-specific deletion of Gsk3a and Gsk3b on the size of the mandible and craniofacial skeleton in embryonic mice.

Materials & Methods: Mice were bred to generate cartilage-specific Gsk3a and Gsk3b KO mice. On embryonic day 18.5 (E18.5) the offspring were gathered by caesarian section. Whole mount skeletal staining was completed on the specimens using …

The Genetic Determinants Of Complex Lipid And Lipoprotein Phenotypes, Jacqueline S. Dron

Electronic Thesis and Dissertation Repository

Cardiovascular disease (CVD) is the primary cause of death globally and is estimated to cause one-third of deaths in Canada. Each year, millions of Canadians are affected by CVD despite ongoing efforts to reduce risk through lifestyle modifications and pharmacological therapies. With the expected rise in CVD prevalence due to the obesity epidemic, we need to better understand the genetic basis of heritable, modifiable risk factors, including levels of high-density lipoprotein (HDL) cholesterol and triglyceride, for insights into future therapeutic treatments and risk prediction. Through the use of a targeted next-generation sequencing panel designed specifically to study lipid and metabolic …

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 …

Epigenetics A Decolonizing Science, Wade Paul

Electronic Thesis and Dissertation Repository

Epigenetics is the study of gene expression that does not entail alterations to the actual DNA. Decolonization is a theoretical and political movement that seeks to deconstruct colonial institutions and ideologies and reconstruct new and balanced approaches that accept and respect Indigenous worldviews. This project studies the decolonizing potential of epigenetics. Using genealogy as the method, the study establishes a long history of reductionist and deterministic thought that shaped the study of genetic science. Particular instances like thrift gene theory are explored to highlight how genetic explanations have been detrimental to the health and wellbeing of Indigenous people and illustrate …

Advanced Phenotyping Of Otosclerosis In An Ontario Population And Two Large Newfoundland Families, Matthew B. Lucas

Electronic Thesis and Dissertation Repository

Otosclerosis is a relatively common hearing loss disorder characterized by abnormal bone growth in the otic capsule leading to stapes fixation. In approximately half of cases, otosclerosis is inherited as an autosomal dominant trait. Typically, gene discovery efforts rely on surgical confirmation, audiometry and occasionally acoustic reflexes to identify affected cases of otosclerosis within families, requiring that the otosclerosis was at an advanced stage to be detected. This makes it difficult to identify individuals with early otosclerosis. The use of advanced phenotyping to identify cases of otosclerosis was tested in an Ontario otosclerotic population as well as in two large …

Generation Of Conditional Ku70 Knockouts In Human Cell Lines Using Crispr/Cas9 And Dual-Nuclease Crispr/Tevcas9, Gursimran Parmar

Electronic Thesis and Dissertation Repository

The Ku heterodimer, Ku70 and Ku80, plays a key role in DNA repair. Viable Ku70 knockouts exist in mice but not in human cell lines. The objective was to create Ku70 knockouts and evaluate knockout viability in human cells using CRISPR/Cas9 and TevCas9. Editing is achieved by Cas9 through one sequence-specific blunt cut accompanied by error-prone DNA repair. However, TevCas9, a novel fusion protein of Cas9 and I-Tev, creates two non-compatible DNA breaks and biases editing events towards a small deletion. Ku70 has five processed pseudogenes therefore intron-exon junctions were targeted by gRNA and a cell line stably transfected with …

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 …

Analysis Of The Chemotactic And Anti-Ovarian Response To Honeybee Queen Mandibular Pheromone (Qmp) And Its Constituent Components In Drosophila Melanogaster, Suhayr Solangi

Electronic Thesis and Dissertation Repository

Drosophila melanogaster can mimic qualities of honeybee altruism mediated by queen mandibular pheromone (QMP), a honeybee pheromone, which includes suppression of oogenesis and chemotactic attraction of males to sources of QMP. In this study, I assessed chemotaxis to the components of synthetic QMP (sQMP): the phenols; methyl-p-hydroxybenzoate (HOB) and 4-hydroxy-3-methoxyphenylethanol (HVA), and decenoic acids; 9-hydroxy-decenoic acid (9-HDA) and 9-oxo-decenoic acid (9-ODA). I found that the chemotactic response to these components is sexually dimorphic and they have complex interactions with one another. I conducted a screen to inhibit olfactory receptor neurons (ORN) using tetanus toxin (TeTx) and OrGAL4 drivers. Of the …

Rna Interference Of Worker Sterility Genes: Testing Mechanisms Of Reproductive Regulation In Apis Mellifera, Anthony J. Gallo

Electronic Thesis and Dissertation Repository

Social insects such as the honey bee (Apis mellifera) are well known for their reproductive division of labour and eusocial colony systems. Honey bee workers forgo reproduction in favour of being selfless in directing reproductive benefits towards their queen mother. This altruistic tendency is a result of both behavioural and physiological changes under control of the presence of the queen’s mandibular pheromone. The genetic mechanism that underlies this response is, however, not well understood. Here, this study used RNA interference to knock down the expression of single genes (fruitless and ftz-f1) that have been previously identified …

Assessing The Role Of Drosophila Melanogaster Neuroligin 3 On Social Spacing And Climbing Behaviour, J. Wesley Robinson

Electronic Thesis and Dissertation Repository

Autism spectrum disorders can be clinically defined in part by impairments of social interactions. Social interactions can be modeled in Drosophila melanogaster with behaviours such as social spacing. Here, I examined the effects of autism-related gene neuroligin 3 on fly social spacing. I hypothesized if neuroligin 3 is mutated or gene expression is targeted for knockdown, then flies will have altered social space in males and females at different ages. Using the social space assay, I found that different mutations to neuroligin 3 change the fly’s behavior, in a mutation and sex-specific manner. Using an antibody against Nlg3, I localized …

Cross-Species Utility Of The Mouse Diversity Genotyping Array In Assaying Single Nucleotide Polymorphisms, Rachel Kelly

Electronic Thesis and Dissertation Repository

In the study of genetic diversity in non-model species there is a notable lack of the low-cost, high resolution tools that are readily available for model organisms. Genotyping microarray technology for model organisms is well-developed, affordable, and potentially adaptable for cross-species hybridization. The Mouse Diversity Genotyping Array (MDGA), a single nucleotide polymorphism (SNP) genotyping tool designed for M. musculus, was tested as a tool to survey genomic diversity of wild species for inter-order, inter-family, inter-genus, and intra-genus comparisons. Application of the MDGA cross-species provides genetic distance information that reflects known taxonomic relationships reported previously between non-model species, but there …

The Fruitless Gene Influences Female Mate Preference In Drosophila, Tabashir A. Chowdhury

Electronic Thesis and Dissertation Repository

Species can arise as a result of reproductive barriers that prevent gene flow between diverging populations that force them to remain isolated from one another. Behavioural isolation is one of the earliest acting reproductive barriers determined by the evolution of mating preferences that prevent inter-specific matings. Several traits have been identified that contribute to behavioural isolation, but the genetic basis of interspecific female preference is yet to be determined. I used genetic mapping techniques to identify and confirm that the fruitless gene is affecting species-specific female rejection of interspecies males, contributing to the behavioural isolation between Drosophila melanogaster and D. …

The Role Of H3k4 Methyltransferases In Drosophila Memory, Nicholas Raun

Electronic Thesis and Dissertation Repository

Gene transcription required for long-term memory requires the modification of histones. However, there are still many uncertainties about the identity and spatial expression of genes regulated by histone modifications during memory related processes. In this project I examined the role of Drosophila melanogaster methyltransferases Set1 and trx in courtship memory. Genetic knockdown of Set1 and trx in the mushroom body (MB) revealed that Set1 was necessary for short- and long-term memory, while trx was only required for long-term memory. Transcriptional profiling of MBs following trx-knockdown revealed expression changes in MB-enriched genes and genes involved in RNA processing. Among the …

Spatial And Temporal Patterns Of Neutral And Adaptive Genetic Variation In The Alpine Butterfly, Parnassius Smintheus, Maryam Jangjoo

Electronic Thesis and Dissertation Repository

Understanding how much genetic diversity exists in populations, and the processes that maintain that diversity, has been a central focus of population genetics. The evolutionary processes that determine patterns of genetic diversity depend on underlying ecological processes such as dispersal and changes in population size. In this thesis, I examine the influence of dispersal and population dynamics on neutral and adaptive genetic variation in a naturally occurring network of populations of the alpine butterfly, Parnassius smintheus.

My first objective was to determine the combined consequences of demographic bottlenecks and dispersal on neutral genetic variation within and among populations. Using …

Creating Tools To Determine Whether Katanin 60 Affects Female Rejection Of Males In Drosophila, Joshua R. Isaacson

Electronic Thesis and Dissertation Repository

During courtship, it is vital for organisms to recognize conspecifics because of the costs associated with forming interspecies hybrids. Many organisms use species-specific cues to recognize potential mates. These cues are perceived and evaluated via neural pathways. The genetic basis of how species-specific cues are evaluated and processed into receptive or rejection behaviour remains almost entirely unknown. The gene Katanin 60 (Kat60) has previously been identified as contributing to interspecific mate rejection between Drosophila melanogaster and D. simulans. I use the CRISPR/Cas9 system and RNA interference (RNAi) to confirm if Kat60 influences female receptivity between D. melanogaster …

Production Of A Candidate Recombinant Protein Vaccine For Mannheimia Haemolytica In Lettuce And Tobacco Chloroplasts, Coby K. Martin

Electronic Thesis and Dissertation Repository

The cattle industry worldwide is ravaged by bovine respiratory disease (BRD), a bacterial disease caused by Mannheimia haemolytica. Recent efforts to design vaccines against M. haemolytica focus on a virulence factor, leukotoxin, in addition to surface lipoproteins. Plant-based protein production is a safe and inexpensive alternative to traditional methods. Edible vaccines deliver antigens to pharyngeal tissues, which can provide local immunization against M. haemolytica prior to its progression into the lungs. In this project, a chimeric protein containing M. haemolytica antigens was produced in tobacco chloroplasts as a candidate edible vaccine for BRD. Attempts were made to transform lettuce …

A Genetic Screen To Identify Fission Yeast Genes With Roles In Protecting Against Perturbation Of The Actin Cytoskeleton, Dorota Michalski

Electronic Thesis and Dissertation Repository

In the fission yeast, Schizosaccharomyces pombe, stress upon the cell division machinery leads to the activation of a cytokinesis checkpoint. This checkpoint results in a delay in cell cycle progression and the prolonged maintenance of a cytokinesis competent cellular state. In this state the cell is able to continuously reform/repair the actomyosin ring until cell division is achieved. To uncover genes that play a role in enforcing this checkpoint, the actin depolymerizing drug Latrunculin A (LatA) was used to perturb the cytokinetic machinery in a set of 3400 viable haploid S. pombe gene deletion mutants. Thirty-eight gene deletion mutants hypersensitive …

Chromatin Accessibility Dynamics In The Arabidopsis Root Epidermis And Endodermis During Cold Acclimation, Shawn Hoogstra

Electronic Thesis and Dissertation Repository

Understanding cell-type specific transcriptional responses to environmental conditions is limited by a lack of knowledge of transcriptional control due to epigenetic dynamics. Additionally, cell-type analyses are limited by difficulties in applying current technologies to single cell-types. A novel DNase-seq protocol and analysis procedure, deemed DNase-DTS, was developed to identify DHSs in the Arabidopsis epidermis and endodermis under control and cold acclimation conditions. Results identified thousands of DHSs within each cell-type and experimental condition. DHSs showed strong association to gene expression, DNA methylation, and histone modifications. A priori mapping of existing DNA binding motifs within accessible genes and the cold C-repeat/dehydration …