Genetics and Genomics Commons^™

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. …

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 …

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 …

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 …

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 …

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.

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 …

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.

The Genome Of Austrofundulus Limnaeus Offers Insights Into Extreme Vertebrate Stress Tolerance And Embryonic Development, Josiah Tad Wagner, Param Priya Singh, Amie L. Romney, Claire L. Riggs, Patrick Minx, Steven Cody Woll, Jake Roush, Wesley C. Warren, Anne Brunet, Jason E. Podrabsky

Center for Life in Extreme Environments Publications

Background: The annual killifish Austrofundulus limnaeus inhabits ephemeral ponds in northern Venezuela, South America, and is an emerging extremophile model for vertebrate diapause, stress tolerance, and evolution. Embryos of A. limnaeus regularly experience extended periods of desiccation and anoxia as a part of their natural history and have unique metabolic and developmental adaptations. Currently, there are limited genomic resources available for gene expression and evolutionary studies that can take advantage of A. limnaeus as a unique model system.

Results: We describe the first draft genome sequence of A. limnaeus. The genome was assembled de novo using a merged assembly strategy …

Identification Of Novel Mites (Miniature Inverted-Repeat Transposable Elements) In Coxiella Burnetii: Implications For Protein And Small Rna Evolution, Shaun Wachter, Rahul Raghavan, Jenny Wachter, Michael F. Minnick

Biology Faculty Publications and Presentations

Background: Coxiella burnetii is a Gram-negative gammaproteobacterium and zoonotic agent of Q fever. C. burnetii’s genome contains an abundance of pseudogenes and numerous selfish genetic elements. MITEs (miniature invertedrepeat transposable elements) are non-autonomous transposons that occur in all domains of life and are thought to be insertion sequences (ISs) that have lost their transposase function. Like most transposable elements (TEs), MITEs are thought to play an active role in evolution by altering gene function and expression through insertion and deletion activities. However, information regarding bacterial MITEs is limited. Results: We describe two MITE families discovered during research on small non-coding …

Transcriptomic Regulation Of Alternative Phenotypic Trajectories In Embryos Of The Annual Killifish Austrofundulus Limnaeus, Amie L. Romney

Dissertations and Theses

The Annual Killifish, Austrofundulus limnaeus, survives the seasonal drying of their pond habitat in the form of embryos entering diapause midway through development. The diapause trajectory is one of two developmental phenotypes. Alternatively, individuals can "escape" entry into diapause and develop continuously until hatching. The alternative phenotypes of A. limnaeus are a form of developmental plasticity that provides this species with a physiological adaption for surviving stressful environments. The developmental trajectory of an embryo is not distinguishable morphologically upon fertilization and phenotype is believed to be influenced by maternal provisioning within the egg based on observations of offspring phenotype …

Prebiotic Rna Network Formation: A Taxonomy Of Molecular Cooperation, Cole Mathis, Sanjay N. Ramprasad, Sara Imari Walker, Niles Lehman

Chemistry Faculty Publications and Presentations

Cooperation is essential for evolution of biological complexity. Recent work has shown game theoretic arguments, commonly used to model biological cooperation, can also illuminate the dynamics of chemical systems. Here we investigate the types of cooperation possible in a real RNA system based on the Azoarcusribozyme, by constructing a taxonomy of possible cooperative groups. We construct a computational model of this system to investigate the features of the real system promoting cooperation. We find triplet interactions among genotypes are intrinsically biased towards cooperation due to the particular distribution of catalytic rate constants measured empirically in the real system. For other …

Life’S Late Digital Revolution And Why It Matters For The Study Of The Origins Of Life, David A. Baum, Niles Lehman

Chemistry Faculty Publications and Presentations

The information contained in life exists in two forms, analog and digital. Analog information is manifest mainly in the differing concentrations of chemicals that get passed from generation to generation and can vary from cell to cell. Digital information is encoded in linear polymers such as DNA and RNA, whose side chains come in discrete chemical forms. Here, we argue that the analog form of information preceded the digital. Acceptance of this dichotomy, and this progression, can help direct future studies on how life originated and initially complexified on the primordial Earth, as well as expected trajectories for other, independent …

Accumulation And Expression Of Multiple Antibiotic Resistance Genes In Arcobacter Cryaerophilus That Thrives In Sewage, Jess A. Millar, Rahul Raghavan

Biology Faculty Publications and Presentations

We explored the bacterial diversity of untreated sewage influent samples of a wastewater treatment plant in Tucson, AZ and discovered that Arcobacter cryaerophilus, an emerging human pathogen of animal origin, was the most dominant bacterium. The other highly prevalent bacteria were members of the phyla Bacteroidetes and Firmicutes, which are major constituents of human gut microbiome, indicating that bacteria of human and animal origin intermingle in sewage. By assembling a near-complete genome of A. cryaerophilus, we show that the bacterium has accumulated a large number of antibiotic resistance genes (ARGs) probably enabling it to thrive in the wastewater. We also …

Pcr-Activated Cell Sorting As A General, Cultivation-Free Method For High-Throughput Identification And Enrichment Of Virus Hosts, Shaun W. Lim, Shea T. Lance, Kenneth M. Stedman, Adam R. Abate

Biology Faculty Publications and Presentations

Characterizing virus-host relationships is critical for understanding the impact of a virus on an ecosystem, but is challenging with existing techniques, particularly for uncultivable species. We present a general, cultivation-free approach for identifying phage-associated bacterial cells. Using PCR-activated cell sorting, we interrogate millions of individual bacteria for the presence of specific phage nucleic acids. If the nucleic acids are present, the bacteria are recovered via sorting and their genomes analyzed. This allows targeted recovery of all possible host species in a diverse population associated with a specific phage, and can be easily targeted to identify the hosts of different phages …

Editorial: Genetics, Genomics And –Omics Of Thermophiles, Kian Mau Goh, Kok-Gan Chan, Rajesh Kumar Sani, Edgardo Ruben Donati, Anna-Louise Reysenbach

Biology Faculty Publications and Presentations

Thermophilic Archaea and Bacteria occupy heated environments. Advancement of next-generation sequencing (NGS), single-cell analyses, and combinations of –omics and microscopic technologies have resulted in the discovery of new thermophiles. This e-book consists of a review, and 10 original articles authored by 94 authors. The main aim of this Research Topic of Frontiers in Microbiology was to provide a platform for researchers to describe recent findings on the ecology of thermophiles using NGS, functional genomics, comparative genomics, gene evolution, and extremozyme discovery.

Topological And Thermodynamic Factors That Influence The Evolution Of Small Networks Of Catalytic Rna Species, Jessica Anne Mellor Yeates, Philippe Nghe, Niles Lehman

Chemistry Faculty Publications and Presentations

An RNA-directed recombination reaction can result in a network of interacting RNA species. It is now becoming increasingly apparent that such networks could have been an important feature of the RNA world during the nascent evolution of life on the Earth. However, the means by which such small RNA networks assimilate other available genotypes in the environment to grow and evolve into the more complex networks that are thought to have existed in the prebiotic milieu are not known. Here, we used the ability of fragments of the Azoarcus group I intron ribozyme to covalently self-assemble via genotype-selfish and genotype-cooperative …

Peering Below The Diffraction Limit: Robust And Specific Sorting Of Viruses With Flow Cytometry, Shea T. Lance, David J. Sukovich, Kenneth M. Stedman, Adam R. Abate

Biology Faculty Publications and Presentations

Background: Viruses are incredibly diverse organisms and impact all forms of life on Earth; however, individual virions are challenging to study due to their small size and mass, precluding almost all direct imaging or molecular analysis. Moreover, like microbes, the overwhelming majority of viruses cannot be cultured, impeding isolation, replication, and study of interesting new species. Here, we introduce PCR-activated virus sorting, a method to isolate specific viruses from a heterogeneous population. Specific sorting opens new avenues in the study of uncultivable viruses, including recovering the full genomes of viruses based on genetic fragments in metagenomes, or identifying the …

Investigating The Origin And Functions Of A Novel Small Rna In Escherichia Coli, Fenil Rashmin Kacharia

Dissertations and Theses

Non-coding small RNAs (sRNAs) regulate various cellular processes in bacteria. They bind to a chaperone protein Hfq for stability and regulate gene expression by base-pairing with target mRNAs. Although the importance of sRNAs in bacteria has been well established, the mode of origination of novel sRNA genes is still elusive, mainly because the rapid rate of evolution of sRNAs obscures their original sources. To overcome this impediment, we identified a recently formed sRNA (EcsR2) in E. coli, and show that it evolved from a degraded bacteriophage gene. Our analyses also revealed that young sRNAs such as EcsR2 are expressed …