Life Sciences Commons^™

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 …

Chromatin Regulation By Rb-Interacting Proteins In Cellular Immune Functions, Seung June Kim

Electronic Thesis and Dissertation Repository

The retinoblastoma protein (RB) is historically known for its function in cell cycle control. However, mice carrying targeted Rb1 mutations have revealed that RB serves various non-cell cycle control roles. Notably, RB acts as a scaffold that recruits chromatin regulatory proteins, condensin II and enhancer of zeste homolog 2 (EZH2). These complexes protect the genome integrity through maintaining proper chromosome condensation, long range contacts, and transcriptionally repressive histone modification. This thesis explores the mechanistic links that regulate such RB-condensin II complex or that are leveraged upon pharmacological inhibition of the RB-EZH2 complex. First, I identified potential phosphorylation sites in the …

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 …

Tetr Family Regulator Farr Variation Controls Antimicrobial Fatty Acid Efflux In Staphylococcus Aureus, Camryn M. Bonn

Electronic Thesis and Dissertation Repository

To colonize human skin and survive within abscesses, Staphylococcus aureus has evolved mechanisms to evade host innate defenses. USA300 has become the predominate community-acquired methicillin-resistant S. aureus (CA-MRSA) clone, which can be in part attributed to detoxification of unsaturated free fatty acids (uFFA) found in sebum and the nares. Our lab has previously identified the TetR family regulator FarR responsible for induction of the resistance-nodulation-division (RND) superfamily efflux pump FarE to promote efflux of toxic uFFA. However, RND family efflux pumps remain poorly characterized in Gram-positive species and the mechanism by which FarR regulates FarE has yet to be determined. …

Using Conservation Genetics To Inform Reintroduction Of The Endangered Mottled Duskywing (Erynnis Martialis), Shayla Kroeze

Electronic Thesis and Dissertation Repository

Habitat loss and climate change have caused declines in species diversity and abundance globally, including in butterflies which are important components of many ecosystems. Reintroductions are increasingly used to reverse diversity loss but are most effective when informed using genetics. I developed 24 microsatellites and characterized genetic structure and diversity of the endangered Mottled Duskywing (Erynnis martialis) in Ontario and neighbouring provinces and states. These were used to inform a planned reintroduction in Ontario. Populations had moderate levels of genetic diversity, however all but the largest populations may be subject to appreciable levels of genetic drift. Populations more …

Identification Of Dna Methylation Episignatures For Classification And Phenotype/Genotype Correlation In Mendelian Neurodevelopmental Disorders, John Reilly

Electronic Thesis and Dissertation Repository

ABSTRACT: Diagnosis for neurodevelopmental disorders poses numerous challenges, related to the lack of specific findings and limited understanding of clinical impact of the majority of genetic variation. Epigenomics mechanisms involve chemical modifications in DNA that involve a range of cellular mechanisms. DNA methylation is an epigenetic mechanism involving addition and removal of methyl groups to cytosine residues. These methylation signals form episignatures; patterns of methylation that can be used as biomarkers capable of differentiating neurodevelopmental disorders. EpiSigns have enabled molecular diagnosis of a number of genetic conditions, classification of variants of unknown significance, and provided insights into the pathophysiology of …

Applications Of Nanopore Dna Sequencing For Improved Genome Assembly, Daniel Giguere

Electronic Thesis and Dissertation Repository

An organism's genome is the ultimate determinant of its functional potential. Understanding genomes is therefore essential to understand function, and a foundational knowledge of a genome is required transfer functions to and from microorganisms of interest. Sequencing DNA using nanopores is a recent advance that resolves limitations of previous technologies, enabling an improved understanding of genomes. For this thesis, I improved our understanding of microbial genomes by developing novel approaches to analyze long read sequencing data, setting the foundation for future synthetic biology work.

Long sequencing reads have enabled routine assembly of complete bacterial genomes by directly sequencing DNA extracted …

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 …