Genetics and Genomics Commons^™

Elucidating The Function Of Yedk In Response To Dna Damage, Hank Munro

University Honors Theses

Apurinic/Apyrimidinic (AP) sites are one of the most prevalent forms of DNA damage. These lesions arise spontaneously or during base excision repair of modified DNA bases and are potentially mutagenic in both mammalian and bacterial cells. 5-hydroxymethylcytosine binding, ES cell specific (HMCES), a protein found in eukaryotic cells, has been shown to form a stable DNA-protein crosslink with AP sites in single stranded DNA and to reduce the number of AP sites occurring either spontaneously or after alkylative DNA damage, resulting in increased genome stability. YedK, the Escherichia coli ortholog of HMCES exhibits some of the same biochemical properties as …

Exploring Muslim American Attitudes Toward Genetic Testing: Perceptions, Barriers, And Ethical Considerations, Hannah Mahmoud

University Honors Theses

This thesis explores perceptions and attitudes toward genetic testing within the Muslim American community, a group often underrepresented in genomic research and public health discourse. Using a community-distributed digital survey, data was collected from 50 self-identified Muslim Americans on their familiarity with genetic testing, reproductive and ethical considerations, and the influence of religious factors. While only 18% had undergone genetic testing themselves, many were familiar through family or friends, and most expressed cautious interest—especially when results could influence future family planning. Education level, age, and religious values shaped both comfort and understanding.

A key theme was the desire for culturally …

Investigating A Link Between Dna Repair And Dna Replication In Escherichia Coli Using A Bacterial Two-Hybrid System, Lo Cooper

University Honors Theses

Cells rely on nucleotide excision repair (NER) to remove bulky DNA lesions, such as those caused by UV light. In Escherichia coli, NER involves the UvrABC complex, and includes two main pathways, global genomic repair and transcription-coupled repair (TCR). While TCR, which preferentially removes lesions that block RNA polymerase on the transcribed strand of active genes, is well studied, less is known about whether a similar coupling between repair proteins and replisomes blocked by damaged DNA exists. Such a process has been suggested by a high throughput interactome study, using the replisome subunit HolC as bait and the damage …

Exploring Natural Competence Of Escherichia Coli Through Biofilm Formation, Thulni Liyanaarachchi

University Honors Theses

Escherichia coli is a species not known for natural competence; however, specific growth conditions can induce the process in this bacterium due to the presence of homologous competence genes. These conditions could be met with biofilm formation through an active growth phase in the two-layer architecture. Therefore, my thesis examined whether natural competence is exhibited in E. coli during biofilm formation as determined by the genetic transfer of ampicillin and chloramphenicol-resistance genes between two separate strains. The experiments were broken into three aims to determine the morphology of the biofilm in inter-strain co-cultures and cell-DNA mixes, the effect of …

Lagging Brain Gene Expression Patterns Of Drosophila Melanogaster Young Adult Males Confound Comparisons Between Sexes, Flannery Mclamb, Zuying Feng, Jeanne P. Vu, Lindsey Griffin, Miguel F. Vasquez, Goran Bozinovic

Center for Life in Extreme Environments Publications

Many species, including fruit flies (Drosophila melanogaster), are sexually dimorphic. Phenotypic variation in morphology, physiology, and behavior can affect development, reproduction, health, and aging. Therefore, designating sex as a variable and sex-blocking should be considered when designing experiments. The brain regulates phenotypes throughout the lifespan by balancing survival and reproduction, and sex-specific development at each life stage is likely. Changes in morphology and physiology are governed by differential gene expression, a quantifiable molecular marker for age- and sex-specific variations. We assessed the fruit fly brain transcriptome at three adult ages for gene expression signatures of sex, age, and sex-by-age: 6698 …

Isolation Of Gametophytic Selection And Selective Embryo Abortion In Mimulus Guttatus, Desmond C. Willson

University Honors Theses

A lack of genomic studies examining gametophytic selection (GS) and selective embryo abortion (SEA)--which occur during the reproduction of angiosperms--leaves questions regarding the adaptive and evolutionary effects of these processes. Analyzing deviations from Mendelian segregation offers an avenue for identifying loci targeted by GS and SEA, and their contributions to purging of genetic load. However, other selective processes such as meiotic drive and cytonuclear interactions, as well as pollen and ovule abortion, can cause distortion. To distinguish the effects of GS and SEA from other causes of distortion, we will perform reciprocal crosses between highly homozygous and highly heterozygous individuals …

Improved Genome Maintenance And Dna Replication In The Anoxia Tolerant Annual Killifish, Riley A. Roth-Carter

Student Research Symposium

Timely and faithful replication of the genome is a requirement for cell survival and proliferation, with errors in this process leading to cancers and cell death. DNA replication during exposure to stressful conditions can lead to increased mutational burden, with collapsed replication forks causing mutations leading to cancers due to loss of repair capabilities during these exposures. Learning how stressful DNA replication takes places can lead to a better understanding of how resistant cancers survive similar conditions, like hypoxic tumor microenvironment, direct irradiation, and DNA damaging chemotherapeutics. Using an extremophile model, Austrofundulus limnaeus, which can survive these genotoxic stressors could …

Guide Rna Design And Delivery For Crispr/Cas9 Editing In Annual Killifish, Keria N. Moritsugu-Vandehey, Isabel Henkes, Yekaterina Chmykh, Amie Romney, Jason Podrabsky

Student Research Symposium

The CRISPR-Cas9 genome editing tool has shown to be successful in knocking out genes in model organisms such as zebrafish, turquoise killifish, and cichlid fish. CRISPR-Cas9 genome editing has been demonstrated in many species of fish, but this technology has not been verified in the annual killifish, Austrofundulus limnaeus. We hypothesize that targeted editing of the tyrosinase gene in embryos of A. limnaeus would lead to the development of fish without the ability to produce melanin, the black/brown pigment molecule. Early embryos (1-cell stage) were injected with a Cas9 cocktail containing a mix of guide RNA molecules that target …

Selection During Reproduction In Mimulus Guttatus, Desmond C. Willson, Karla De Lima Berg, Mitch Cruzan

Student Research Symposium

A lack of genomic studies examining gametophytic selection and selective embryo abortion—which occur during the reproduction of angiosperms—leaves questions regarding the adaptive and evolutionary effects of these processes. Analyzing deviations from Mendelian segregation offers an avenue for identifying loci targeted by GS and SEA, and their contributions to purging of genetic load. However, other selective processes such as meiotic drive and cytonuclear interactions, as well as pollen and ovule abortion, can cause distortion. To distinguish the effects of GS and SEA from other causes of distortion, we will perform reciprocal crosses between highly homozygous and highly heterozygous individuals of Mimulus …

Genome Editing Using Crispr-Cas9 In Annual Killifish Species, Keria Moritsugu-Vandehey

University Honors Theses

CRISPR-Cas9 genome editing has been used successfully to knock out genes in model organisms such as zebrafish, turquoise killifish, and cichlid fish. CRISPR-Cas9 genome editing has not been verified in the annual killifish, Austrofundulus limnaeus. We hypothesize that targeted editing of the tyrosinase gene in embryos of A. limnaeus will lead to fish without the ability to produce black pigment. Embryos at the 1-cell stage were injected with a Cas9 cocktail containing a mix of guide RNA molecules that target the genomic sequence of the tyrosinase gene and either an mRNA coding for the Cas9 protein or Cas9 protein. …

Genetic Considerations For The Conservation Of The Red Junglefowl, Courtney Lee Mcpheron

University Honors Theses

The undomesticated wild populations of our domestic species deserve heightened consideration when it comes to their conservation. Not only do they carry significant socio-cultural and economic roles, but they offer an exceptionally unique case study for population genetics. The red junglefowl (Gallus gallus) of southern and south-eastern Asia is considered to be the living ancestor and progenitor of the domestic chicken. This literature review examines how published research has evaluated its genetic relationship with the chicken and implications for its conservation. A special emphasis is given to the threat of genetic introgression with domestic and feral chicken populations …

Investigating The Role Of Holoenzyme C In Restoring Replication Following Uv-Induced Dna Damage In Escherichia Coli, Rahul Shimpi

University Honors Theses

The recovery of replication following UV-induced DNA damage in Escherichia coli correlates with the time at which the lesions are repaired, suggesting that the two processes may be coupled. holC encodes the Chi-subunit of replicative DNA polymerase III, and is nonessential for viability, but renders cells hypersensitive to UV-induced damage when mutated, suggesting it may play a specific role in restoring replication when it encounters DNA damage. Here, I characterized the role of HolC in restoring DNA replication following disruption by UV-induced damage. I found that survival following UV in strains deleted for holC was similar to that of strains …

Effects Of Hormone Replacement Therapy (Hrt) On Gene Expression In The Amyloid Processing Pathway Of Ovariectomized Rhesus Macaque Females Under An Obesogenic Diet, Megan Ball

University Honors Theses

Estrogens rapidly decline at the onset of menopause, putting women at higher risk of osteoporosis, obesity, and neurodegenerative diseases, including Alzheimer’s disease (AD). Estradiol hormone therapies (HT) have been suggested to limit these negative effects on women, with controversial findings as to their effectiveness. A study at OHSU recently found differentially expressed genes (DEGs) using RNAseq between ovariectomized/hysterectomized (OvH) old (range = 19.4–23.2 years) female rhesus macaques on HT and those on a placebo on chronic western style diet (WSD). The DEGs identified in the amyloid processing pathway of the amygdala were selected for validation using RT-qPCR because β-amyloid peptide …

Mitonuclear Mismatch Is Associated With Increased Male Frequency, Outcrossing, And Male Sperm Size In Experimentally-Evolved C. Elegans, Brent William Bever

Dissertations and Theses

We provide the first controlled study of how male frequencies and rates of outcrossing evolve in response to mitonuclear mismatch by allowing replicate lineages of C. elegans nematodes containing either mitochondrial or nuclear mutations of electron transport chain (ETC) genes to evolve under three sexual systems: facultatively outcrossing (wildtype), obligately selfing, and obligately outcrossing. In partial support of a tenet of the mitonuclear sex hypothesis, which predicts that outcrossing will be favored in cases of mitonuclear mismatch, we found evolution of increased male frequency in at least one replicate line of all four ETC mutant backgrounds tested--nuclear isp-1, mitochondrial …

Expression And Function Of Transcription Factors Foxa1, Hoxb13 And Cdx2 In Prostate Cancer, Hamsat B. Anwar

University Honors Theses

Prostate cancer (PC) is the second leading cause of death in men, affecting around 190 thousand patients in 2020 alone (National Institute of Cancer, 2020). Much of the current research focuses on treatments for advanced PC, which is problematic due to the rapid evolution of tumors and development of treatment resistance. Cancer early detection presents a better approach to control and treat patients before they acquire an incurable disease. Earlier diagnosis of patients leads to better prognosis and a more comfortable treatment process (Etzioni et al., 2003). However, we currently lack molecular markers to stratify PC during its early stages. …

A Basic Ddradseq Two‐Enzyme Protocol Performs Well With Herbarium And Silica‐Dried Tissues Across Four Genera, Ingrid E. Jordon‐Thaden, James B. Beck, Catherine A. Rushworth, Michael D. Windham, Nick Diaz, Jason T. Cantley, Christopher T. Martine, Carl J. Rothfels

Biology Faculty Publications and Presentations

PREMISE: The ability to sequence genome-scale data from herbarium specimens would allow for the economical development of data sets with broad taxonomic and geographic sampling that would otherwise not be possible. Here, we evaluate the utility of a basic double-digest restriction site–associated DNA sequencing (ddRADseq) protocol using DNAs from four genera extracted from both silica-dried and herbarium tissue.

METHODS: DNAs from Draba, Boechera, Solidago, and Ilex were processed with a ddRADseq protocol. The effects of DNA degradation, taxon, and specimen age were assessed. RESULTS: Although taxon, preservation method, and specimen age affected data recovery, large phylogenetically informative data sets were …

Unveiling Crucivirus Diversity By Mining Metagenomic Data, Ignacio De La Higuera, George Kasun, Ellis L. Torrance, Alyssa A. Pratt, Amberlee Maluenda, Jonathan Colombet, Maxime Bisseux, Viviane Ravet, Anisha Dayaram, Daisy Stainton, Simona Kraberger, Peyman Zawar-Reza, Sharyn Goldstien, James V. Briskie, Robyn White, Helen Taylor, Christopher Gomez, David G. Ainley, Jon S. Harding, Rafaela S. Fontenele, Joshua Schreck, Simone Ribeiro, Stephen A. Oswald, Jennifer M. Arnold, François Enault, Arvind Varsani, Kenneth M. Stedman

Biology Faculty Publications and Presentations

The discovery of cruciviruses revealed the most explicit example of a common protein homologue between DNA and RNA viruses to date. Cruciviruses are a novel group of circular Rep-encoding single-stranded DNA (ssDNA) (CRESSDNA) viruses that encode capsid proteins that are most closely related to those encoded by RNA viruses in the family Tombusviridae. The apparent chimeric nature of the two core proteins encoded by crucivirus genomes suggests horizontal gene transfer of capsid genes between DNA and RNA viruses. Here, we identified and characterized 451 new crucivirus genomes and 10 capsid-encoding circular genetic elements through de novo assembly and mining of …

Roadmap For Naming Uncultivated Archaea And Bacteria, Alison Murray, John Freudenstein, Simonetta Gribaldo, Roland Hatzenpichler, Philip Hugenholtz, Peter Kämpfer, Konstantinos T. Konstantinidis, Christopher E. Lane, R. Thane Papke, Anna-Louise Reysenbach, Multiple Additional Authors

Biology Faculty Publications and Presentations

The assembly of single-amplified genomes (SAGs) and metagenome-assembled genomes (MAGs) has led to a surge in genome-based discoveries of members affiliated with Archaea and Bacteria, bringing with it a need to develop guidelines for nomenclature of uncultivated microorganisms. The International Code of Nomenclature of Prokaryotes (ICNP) only recognizes cultures as ‘type material’, thereby preventing the naming of uncultivated organisms. In this Consensus Statement, we propose two potential paths to solve this nomenclatural conundrum. One option is the adoption of previously proposed modifications to the ICNP to recognize DNA sequences as acceptable type material; the other option creates a nomenclatural code …

Accumulation And Transmission Dynamics Of A Naturally-Occurring Mtdna Deletion In Caenorhabditis Briggsae, Jennifer Anne Sullins

Dissertations and Theses

Maintaining mitochondrial genome sequence integrity is essential for preserving normal mitochondrial function. Several human diseases have been associated with heteroplasmic mitochondrial genome mutations, but few genetic systems can simultaneously represent pathogenic mitochondrial genome evolution and inheritance. The nematode Caenorhabditis briggsae is one such model. Natural C. briggsae isolates are globally-distributed and phylogenetically grouped into three distinct clades, with isolates exhibiting varying levels of a large-scale mtDNA deletion, nad5∆. Furthermore, a small subset of clade II isolates exhibits putative compensatory mutations that may reduce the risk of deletion formation and accumulation in those populations. In this thesis, the author characterizes the …

Displacement Of The Transcription Factor B Reader Domain During Transcription Initiation, Stefan Dexl, Robert Reichelt, Katharina Kraatz, Sarah Schulz, Dina Grohmann, Michael S. Bartlett, Michael Thomm

Biology Faculty Publications and Presentations

Transcription initiation by archaeal RNA polymerase (RNAP) and eukaryotic RNAP II requires the general transcription factor (TF) B/ IIB. Structural analyses of eukaryotic transcription initiation complexes locate the B-reader domain of TFIIB in close proximity to the active site of RNAP II. Here, we present the first crosslinking mapping data that describe the dynamic transitions of an archaeal TFB to provide evidence for structural rearrangements within the transcription complex during transition from initiation to early elongation phase of transcription. Using a highly specific UV-inducible crosslinking system based on the unnatural amino acid para-benzoyl-phenylalanine allowed us to analyze contacts of …

Impact Of Suburban Landscape Features On Gene Flow Of The Model Invasive Grass, Brachypodium Sylvaticum, Tina Marie Arredondo

Dissertations and Theses

Rapid range expansion of newly invasive species provides a unique opportunity for studying patterns of dispersal and gene flow. In this thesis, I examined the effect of landscape features on gene flow in the invasive grass Brachypodium sylvaticum at the edge of its expanding range. I used genome-wide Single Nucleotide Polymorphism (SNP) surveys of individuals from 22 locations in the Clackamas Watershed in the Portland, Oregon metropolitan region to assess genetic diversity and structure, to identify putative source populations, and to conduct landscape genetic analyses. Resistance surfaces were created for each landscape feature, using ResistanceGA to optimize resistance parameters. My …

Comparative Genetic And Genomic Analysis Of The Novel Fusellovirus Sulfolobus Spindle-Shaped Virus 10, David Andrew Goodman

Dissertations and Theses

Viruses that infect thermophilic Archaea are unique in both their structure and genetic makeup. The lemon-shaped fuselloviruses - which infect members of the order Sulfolobales, growing optimally at 80º C and pH 3 - are some of the most ubiquitous and best studied viruses of the thermoacidophilic Archaea. They provide a malleable and useful genetic tool for probing into the functions of their host, as well as the host responses to infection. Nonetheless, much about these viruses remains to be learned to further understand their morphological, genetic, and life cycle characteristics.

In order to investigate these aspects of these …

Small Non-Coding Rna Expression And Vertebrate Anoxia Tolerance, Claire L. Riggs, Amanda Summers, Daniel E. Warren, Göran E. Nilsson, Sjannie Lefevre, W. W. Dowd, Sarah Milton, Jason E. Podrabsky

Biology Faculty Publications and Presentations

Background: Extreme anoxia tolerance requires a metabolic depression whose modulation could involve small non-coding RNAs (small ncRNAs), which are specific, rapid, and reversible regulators of gene expression. A previous study of small ncRNA expression in embryos of the annual killifish Austrofundulus limnaeus, the most anoxiatolerant vertebrate known, revealed a specific expression pattern of small ncRNAs that could play important roles in anoxia tolerance. Here, we conduct a comparative study on the presence and expression of small ncRNAs in the most anoxia-tolerant representatives of several major vertebrate lineages, to investigate the evolution of and mechanisms supporting extreme anoxia tolerance. The epaulette …

Water Flow And Biofilm Cover Influence Environmental Dna Detection In Recirculating Streams, Arial Shogren, Jennifer L. Tank, Scott P. Egan, Olivia August, Emma J. Rosi, Brittany R. Hanrahan, Mark A. Renshaw, Crysta A. Gantz, Diogo Bolster

Environmental Science and Management Faculty Publications and Presentations

The increasing use of environmental DNA (eDNA) for determination of species presence in aquatic ecosystems is an invaluable technique for both ecology as a field and for the management of aquatic ecosystems. We examined the degradation dynamics of fish eDNA using an experimental array of recirculating streams, also using a “nested” primer assay to estimate degradation among eDNA fragment sizes. We introduced eDNA into streams with a range of water velocities (0.1–0.8 m s–1) and substrate biofilm coverage (0–100%) and monitored eDNA concentrations over time (∼10 d) to assess how biophysical conditions influence eDNA persistence. We found that the presence …

Viral Recombination: Ecology, Evolution, And Pathogenesis, Kenneth M. Stedman

Biology Faculty Publications and Presentations

Recombination between and within virus genomes is being increasingly recognized as a major driver of virus evolution. Virus evolution can lead to changes in virus pathogenesis and virus ecology. The ubiquity of high-throughput sequencing of multiple virus isolates has revolutionized data acquisition, thus the editors of Viruses decided that a Special Issue on viral recombination was appropriate.

Comparative Genetic And Genomic Analysis Of The Novel Fusellovirus Sulfolobus Spindle-Shaped Virus 10, David Andrew Goodman, Kenneth M. Stedman

Biology Faculty Publications and Presentations

Viruses that infect thermophilic Archaea are unique in both their structure and genetic makeup. The lemon-shaped fuselloviruses—which infect members of the order Sulfolobales, growing optimally at 80 C and pH 3—are some of the most ubiquitous and best studied viruses of the thermoacidophilic Archaea. Nonetheless, much remains to be learned about these viruses. In order to investigate fusellovirus evolution, we have isolated and characterized a novel fusellovirus, Sulfolobus spindle-shaped virus 10 (formerly SSV-L1). Comparative genomic analyses highlight significant similarity with both SSV8 and SSV9, as well as conservation of promoter elements within the Fuselloviridae. SSV10 encodes five ORFs with no …

Completion Of Dna Replication In Escherichia Coli, Brian Michael Wendel

Dissertations and Theses

To maintain genomic integrity, all cells must accurately duplicate their genetic material in order to provide intact and complete copies to each daughter cell following cell division. Successful inheritance of chromosomal information without changing even a single nucleotide requires accurate and robust DNA replication. This requires that cells tightly control replication initiation from the origin(s), processive elongation of the replisome, and the completion of DNA replication by resolving convergent replication forks ensuring that each sequence is duplicated without alteration. Unlike initiation and elongation, the process by which replication forks converge and are resolved into two discrete, inheritable DNA molecules is …

Investigating The Role Of Genomic Variation In Susceptibility To Environmental Chemicals Across Populations, Lindsay Adrian Holden

Dissertations and Theses

No two individuals are identical. This is true at the genetic level and at the phenotypic level. One of the traits that varies between populations is toxicant susceptibility: some individuals are sensitive to the effects of environmental chemical exposure, and others are resistant. This body of work aims to address the impact of genomic copy number variants (CNV)--large (>1 Kb) duplications or deletions across the genome--on the toxicant-susceptibility phenotype.

Herein copy number variants were characterized across three commonly used laboratory strains of zebrafish (Danio rerio) and mRNA expression phenotypes were identified in the same strains. It was found that …

Multivalency Regulates Activity In An Intrinsically Disordered Transcription Factor, Sarah Clark, Janette B. Myers, Ashleigh King, Radovan Fiala, Jiri Novacek, Grant Pearce, Steve L. Reichow, Elisar J. Barbar

Chemistry Faculty Publications and Presentations

The transcription factor ASCIZ (ATMIN, ZNF822) has an unusually high number of recognition motifs for the product of its main target gene, the hub protein LC8 (DYNLL1). Using a combination of biophysical methods, structural analysis by NMR and electron microscopy, and cellular transcription assays, we developed a model that proposes a concerted role of intrinsic disorder and multiple LC8 binding events in regulating LC8 transcription. We demonstrate that the long intrinsically disordered C-terminal domain of ASCIZ binds LC8 to form a dynamic ensemble of complexes with a gradient of transcriptional activity that is inversely proportional to LC8 occupancy. The preference …

Draft Genome Sequence Of A Dictyoglomus Sp. From An Enrichment Culture Of A New Zealand Geothermal Spring, Anna-Louise Reysenbach, John A. Donaho, John F. Kelley, Emily St. John, Christina Turner, Mircea Podar, Matthew B. Stott

Biology Faculty Publications and Presentations

A draft genome of a novel Dictyoglomus sp., NZ13-RE01, was obtained from a New Zealand hot spring enrichment culture. The 1,927,012-bp genome is similar in both size and G+C content to other Dictyoglomus spp. Like its relatives, Dictyoglomus sp. NZ13-RE01 encodes many genes involved in complex carbohydrate metabolism.