Digital Commons Network^™

Towards Improved Genomic Surveillance Of Organisms, Joseph L. Sevigny

Doctoral Dissertations

DNA and RNA sequencing is an indispensable tool for the surveillance and monitoring of organisms. Technological advances and research opportunities over the past several years have transformed and driven my research questions; from understanding the impacts of environmental perturbations on complex benthic communities, to tracking and understanding emerging pathogens like SARS-CoV-2. All of them revolve around the use of DNA sequencing to ask fundamental questions about our understanding genomes and their relationship to phenotype and the environment. The advent of sequencing-based characterization has revolutionized our approach to studying organismal communities on a large scale, offering the ability to analyze vast …

Metagenomic Investigation Of Microbial Dark Carbon Fixation, Viral Interactions, And Horizonal Gene Transfer Within A Convergent Margin Subsurface Ecosystem, Timothy Joseph Rogers

Doctoral Dissertations

Convergent margins are geological regions where two or more tectonic plates collide, and the denser “subducting slab” is pushed beneath the less dense overriding plate. As the slab descends, it devolatilizes under higher temperatures and pressures, allowing dissolved inorganic carbon (DIC) and redox active volatile rich fluids to cycle between the upper crust and Earth’s mantle. These fluids migrate through cracks and fissures in the upper mantle and crust, fueling chemolithoautotrophy-based microbial ecosystems in the subsurface before they are expelled on the surface in the form of hydrothermal seeps and springs. Chemolithoautotrophic ecosystems, such as those in the Costa Rican …

Understanding Host-Microbe Interactions In Maize Kernel And Sweetpotato Leaf Metagenomic Profiles., Alison K. Adams

Doctoral Dissertations

Functional and quantitative metagenomic profiling remains challenging and limits our understanding of host-microbe interactions. This body of work aims to mediate these challenges by using a novel quantitative reduced representation sequencing strategy (OmeSeq-qRRS), development of a fully automated software for quantitative metagenomic/microbiome profiling (Qmatey: quantitative metagenomic alignment and taxonomic identification using exact-matching) and implementing these tools for understanding plant-microbe-pathogen interactions in maize and sweetpotato. The next generation sequencing-based OmeSeq-qRRS leverages the strengths of shotgun whole genome sequencing and costs lower that the more affordable amplicon sequencing method. The novel FASTQ data compression/indexing and enhanced-multithreading of the MegaBLAST in Qmatey allows …

Computational Analysis Of Microbial Sequence Data Using Statistics And Machine Learning, Zhixiu Lu

Doctoral Dissertations

Since the discovery of the double helix of DNA in 1953, modern molecular biology has opened the door to a better understanding of how genes control chemical processes within cells, including protein synthesis. Although we are still far from claiming a complete understanding, recent advances in sequencing technologies, increased computational capacity, and more sophisticated computational methods have allowed the development of various new applications that provide further insight into DNA sequence data and how the information they encode impacts living organisms and their environment. Sequencing data can now be used to start identifying the relationships between microorganisms, where they live, …

Accurate Simulation Of Reads And Improved Strategies For Abundance Estimation Supporting Reduced Representation Sequencing For Metagenomics, Ryan Kuster

Doctoral Dissertations

Next generation sequencing has impacted all areas of biology by providing affordable investigations into some of the most complex processes underpinning life. With its ubiquitous application, there is still benefit in considering the nuances of the technology and its downstream analysis. Sequencing libraries produced by fragmenting DNA with restriction enzyme digests limit the scope of sequencing to a reduced set of genomic loci, allowing for deeper sequencing of those regions at a reduced cost per sample. These sequencing libraries have been used to determine genetic markers within populations of closely related individuals due to their sensitivity and preservation within populations. …

Population Genetics Of Populus Trichocarpa For Targeted Breeding As A Biofuel Crop, Cai John

Doctoral Dissertations

Populus trichocarpa (poplar) is a woody species native to the western U.S. and Canada. As a fast-growing crop, it has been under investigation by the Department of Energy as a resource for liquid biofuel production. Having recently expanded the collection of poplar whole-genome sequences so that it spans the entire natural species range, we have the novel opportunity to study adaptive responses across this range. This work starts with an initial proof of concept study in a well-studied portion of the species range that has complete whole-genome sequences and RNA expression. The completeness of these data allow robust validation of …

High Arctic Permafrost Microbial Characterizations: Siberian And Svalbard Microbiology Of Ancient And Active Layer Permafrost, Katie Sipes

Doctoral Dissertations

Permafrost is soil that has remained frozen for at least two years. The active layer is a surface portion above the permafrost that experiences seasonal thaw and refreezing. The environmental characteristics of permafrost and active layer are different but are directly related to each other. As the climate continues to warm, the active layer will expand into the permafrost and the continuously frozen soil will be subjected to seasonal thawing. The organisms that inhabit both the active layer and the permafrost soil will respond differently to the climate based on where in the soil they are present and the soil …

Exploring The Genomic Diversity Of The Trachymyrmex Septentrionalis-Associated Pseudonocardia Symbiont, Sarah Goldstein

Doctoral Dissertations

The focus of this thesis is on the genomic diversity of a fungus-growing ant Trachymyrmex septentrionalis symbiont, the actinomycete bacterium Pseudonocardia. Pseudonocardia symbionts engage in host defense via the production of antimicrobial compounds that protect the symbiosis against fungal pathogens that attack the ant’s food source, pathogens that attack the ant hosts, and more generalized pathogens. These compounds are encoded by biosynthetic gene clusters (BGCs) in the genome of these Pseudonocardia and comprise an untapped resource for drug discovery.

Actinomycete genome sequencing is a key component of modern antimicrobial drug discovery efforts. Short-read sequencing leads to genome fragmentation as …

The Democratization Of Genome Engineering: Tools And Techniques For Manipulating Microorganisms With Crispr-Cas, Brian Joseph Mendoza

Doctoral Dissertations

The discovery of the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) family of genome sequences in bacteria and archaea has led to expansive application of the system as a means of interrogating and modifying genetic material across all kingdoms of life. This dissertation has developed algorithms and accompanying software, collectively named CASPER (CRISPR Associated Software for Pathway Engineering and Research), to identify promising sequences for effectively utilizing CRISPR associated (Cas) proteins in any species or community/metagenome of interest. The on- and off-target activity scoring algorithms improve upon previous work, first by utilizing an evolutionary algorithm and then by employing protein …

Efficient Algorithms For Trees And Networks In Evolutionary Genomics, Sajad Mirzaei

Doctoral Dissertations

Phylogenetic networks are graphs used to abstractly or explicitly visualize the evolutionary relationships between genes, genomes, species, nucleotide sequences, chromosomes, etc. Reticulation events such as hybridization, horizontal gene transfer, recombination, population admixture, gene duplication, etc. are shown in such networks. Phylogenetic trees are a subset of phylogenetic networks used in the absence of such events.

In this dissertation, we focus on some of the existing problems in phylogenetics.

First, we propose a heuristic method called PIRN_S to build near optimal so-called ``hybridization networks" from a given set of phylogenetic trees (called gene trees), representing evolutionary history, such that trees are …

Novel Algorithms For Some Fundamental Big Data Problems, Abdullah-Al Mamun

Doctoral Dissertations

In this digital era data sets are growing rapidly. Storing, processing, and analyzing large volume of data require efficient techniques. These techniques deal with big data problems by providing time efficient methods, effective external memory algorithms, parallel and high performance solutions, and so on. This thesis studies three important areas of big data problems and presents state of the art approaches to address them.

The first part of this thesis discusses the k-mer counting problem. A massive number of bioinformatics applications require counting of k-length substrings in genetically important long strings. Genome assembly, repeat detection, multiple sequence alignment, …

Applying Computational Solutions For Solving Problems In Mammalian Gene Family Evolution And Single Cell Gene Expression Analysis, Ajay Obla

Doctoral Dissertations

Archival abstract submitted

The Microbial Ecology Of Bacterial Lignocellulosic Degradation In The Ocean, Hannah Laing Yee Woo

Doctoral Dissertations

The overarching theme of my dissertation is to study the role of bacteria in lignocellulose degradation. In recent years, more research has investigated the biodegradability of lignocellulose for biofuel production. The components of the lignocellulosic plant cell wall are considered intrinsically recalcitrant due to their structure. However, we hypothesize that these components are not intrinsically recalcitrant but their biodegradation is contingent on the environmental conditions, particularly the bacterial diversity. We believe bacteria will become especially important in lignocellulose degradation in conditions that are unfavorable for white-rot fungi. Therefore, we investigated the potential for lignin degradation by bacteria in the ocean …

Genomic Evaluation Of Male Reproductive Adaptations And Responses To Dehydration In Peromyscus Eremicus (Cactus Mouse), Lauren Kordonowy

Doctoral Dissertations

Research elucidating the genetic architecture of physiological mechanisms enabling survival and reproduction in extreme environments is becoming prominent in evolutionary biology. The desert, in particular, poses numerous challenges for its endemic species, and mammals (and often, rodents) have been the focus for survival adaptations pertaining to water-limitation. However, desert rodent adaptation research has focused predominantly on survival, while potential physiological reproductive adaptations to dehydration have received less attention, aside from research evaluating water as reproductive cue. The fact that we do not know the physiological mechanisms enabling reproduction during dehydration is surprising, as desert rodents must possess adaptations to successfully …

Whole Genome Sequencing As A Tool For Identifying Phenotypic Properties And Underlying Genetic Mechanisms In Staphylococcus Pseudintermedius, Matthew C. Riley

Doctoral Dissertations

Staphylococcus pseudintermedius is a Gram-positive bacterial opportunistic pathogen commonly associated with dermal infections in canines, but capable of causing serious disease in other species. Reports of human infections caused by S. pseudintermedius along with an increase in resistance to multiple antibiotics highlights the importance of this organism. Whole genome sequencing can allow large scale investigation of genetic mechanisms underlying phenotypic properties that contribute to the expansion of successful S. pseudintermedius clonal lineages.

The increase in multidrug and methicillin-resistant S. pseudintermedius (MRSP) may result from horizontal transfer of genetic material between bacterial isolates, yet is thought to be rare in Staphylococci …

Computational Analyses Of Mrna Ribosome Loading In Arabidopsis Thaliana, Joseph Benjamin Ernest

Doctoral Dissertations

Translation of mRNA into protein is a critical step in gene expression, but the principles guiding its regulation at the genome level are not completely understood. Translation can be quantified at a genome scale by measuring the ribosome loading of mRNA—the extent to which mRNA is associated with ribosomes. In this dissertation, I present investigations into how genome-wide ribosome loading is controlled in Arabidopsis thaliana. In chapter 1, I give an overview of regulation of ribosome loading and translation. In chapter 2, I present research demonstrating for the first time that genome-wide ribosome loading in plants is partially controlled by …

Assessment Of Next Generation Sequencing Technologies For De Novo And Hybrid Assemblies Of Challenging Bacterial Genomes, Sagar Mukund Utturkar

Doctoral Dissertations

In past decade, tremendous progress has been made in DNA sequencing methodologies in terms of throughput, speed, read-lengths, along with a sharp decrease in per base cost. These technologies, commonly referred to as next-generation sequencing (NGS) are complimented by the development of hybrid assembly approaches which can utilize multiple NGS platforms. In the first part of my dissertation I performed systematic evaluations and optimizations of nine de novo and hybrid assembly protocols across four novel microbial genomes. While each had strengths and weaknesses, via optimization using multiple strategies I obtained dramatic improvements in overall assembly size and quality. To select …

Computational Identification Of Terpene Synthase Genes And Their Evolutionary Analysis, Qidong Jia

Doctoral Dissertations

Terpenoids, the largest and most structurally and functionally diverse class of natural compounds on earth, are mostly synthesized by plants to be involved in various plant environment interactions. Some terpenoids are classified as primary metabolites essential for plant growth and development. Terpene synthases (TPSs), the key enzymes for terpenoid biosynthesis, are the major determinant of the tremendous diversity of terpenoid carbon skeletons. The TPS genes represent a mid-size family of about 30-100 functional genes in almost all major sequenced plant genomes. TPSs are also found in fungi and bacteria, but microbial TPS genes share low levels of sequence similarity and …

Scalable Optimization Algorithms For High-Throughput Genomic Data, James Lindsay

Doctoral Dissertations

The problem of interpreting biological data is often cast into a mathematical optimization framework where a large body of existing computational theory and practical techniques can be leveraged. While this strategy has been particularly successful in the bioinformatics domain, the massive datasets generated by high-throughput genomic technologies are challenging the scalability of even the most advanced mathematical optimization algorithms. Indeed, as the cost per base of of DNA sequencing has dropped precipitously, even outpacing Moore's law, the size of many bioinformatics problems has grown beyond the limit of existing methods, necessitating new algorithms. This effect is felt even more acutely …

Elucidating The Impact Of Roseophage On Roseobacter Metabolism And Marine Nutrient Cycles, Nana Yaw Darko Ankrah

Doctoral Dissertations

As the most abundant biological entities in marine environments, viruses are an important component of marine food webs. The activity of viruses contributes significantly to the mortality of marine microorganisms, ultimately influencing biological function and chemical composition of aquatic systems by impacting species composition and flow of carbon, nitrogen and other nutrients. Despite the growing recognition that viral activity contributes to marine biogeochemical cycles, the extent to which virus infection reshapes host metabolism and the effect of this alteration on the composition of host lysate remains poorly understood. Additionally, the degree to which natural bacterioplankton communities metabolise the released lysate …

Comparative Genomics Of Microbial Chemoreceptor Sequence, Structure, And Function, Aaron Daniel Fleetwood

Doctoral Dissertations

Microbial chemotaxis receptors (chemoreceptors) are complex proteins that sense the external environment and signal for flagella-mediated motility, serving as the GPS of the cell. In order to sense a myriad of physicochemical signals and adapt to diverse environmental niches, sensory regions of chemoreceptors are frenetically duplicated, mutated, or lost. Conversely, the chemoreceptor signaling region is a highly conserved protein domain. Extreme conservation of this domain is necessary because it determines very specific helical secondary, tertiary, and quaternary structures of the protein while simultaneously choreographing a network of interactions with the adaptor protein CheW and the histidine kinase CheA. This dichotomous …

Development And Integration Of Informatic Tools For Qualitative And Quantitative Characterization Of Proteomic Datasets Generated By Tandem Mass Spectrometry, Rachel Michelle Adams

Doctoral Dissertations

Shotgun proteomic experiments provide qualitative and quantitative analytical information from biological samples ranging in complexity from simple bacterial isolates to higher eukaryotes such as plants and humans and even to communities of microbial organisms. Improvements to instrument performance, sample preparation, and informatic tools are increasing the scope and volume of data that can be analyzed by mass spectrometry (MS). To accommodate for these advances, it is becoming increasingly essential to choose and/or create tools that can not only scale well but also those that make more informed decisions using additional features within the data. Incorporating novel and existing tools into …

Patterns Of Cytosine Methylation In The Genome Of Caenorhabditis Elegans, Kazufusa Okamoto

Doctoral Dissertations

Recent large-scale comparative analysis of cytosine DNA methylation across diverse eukaryotes suggest that early features of DNA methylation present in the last common ancestor of all eukaryotes some 1.6 to 1.8 billion years ago included the methylation of gene bodies and transposable elements (Zemach, McDaniel et al. 2010; Parfrey, Lahr et al. 2011). These potentially ancient patterns may reflect a primitive role of methylation in transcriptional fidelity and as a mechanism to protect the germ line from transposon, or repeat, mediated mutation. Because spurious transcription and mutation are hypothesized to be among the critical limiting factors to genome size, an …

Study Of The Rate And Spectrum Of Spontaneous Mutations, Way Sung

Doctoral Dissertations

Mutations are the initial force responsible for all aspects of genetic variation, and are a central part to evolution in all organisms. Yet despite its importance, the previously high cost that is associated with surveying mutations at a genome-wide scale has limited the understanding of the mutation process in eukaryotes. However, recent high-throughput sequencing technology has greatly reduced the cost of surveying mutations. By applying high-throughput sequencing to mutation accumulation experiments, we have begun to characterize the genome-wide mutation spectrum of eukaryotes.

Across all eukaryotes, we observe a biased rate of G/C-> A/T mutations that exceeds the number of A/T- …

Characterization Of The Extracellular Proteome Of A Natural Microbial Community With An Integrated Mass Spectrometric / Bioinformatic Approach, Brian Keith Erickson

Doctoral Dissertations

Proteomics comprises the identification and characterization of the complete suite of expressed proteins in a given cell, organism or community. The coupling of high performance liquid chromatography (LC) with high throughput mass spectrometry (MS) has provided the foundation for current proteomic progression. The transition from proteomic analysis of a single cultivated microbe to that of natural microbial assemblages has required significant advancement in technology and has provided greater biological understanding of microbial community diversity and function.

To enhance the capabilities of a mass spectrometric based proteomic analysis, an integrated approach combining bioinformatics with analytical preparations and experimental data collection was …

The Maximum Clique Problem: Algorithms, Applications, And Implementations, John David Eblen

Doctoral Dissertations

Computationally hard problems are routinely encountered during the course of solving practical problems. This is commonly dealt with by settling for less than optimal solutions, through the use of heuristics or approximation algorithms. This dissertation examines the alternate possibility of solving such problems exactly, through a detailed study of one particular problem, the maximum clique problem. It discusses algorithms, implementations, and the application of maximum clique results to real-world problems. First, the theoretical roots of the algorithmic method employed are discussed. Then a practical approach is described, which separates out important algorithmic decisions so that the algorithm can be easily …

Targeted Proteomics For The Characterization Of Enriched Microbial Protein Isolates And Protein Complexes, William Judson Hervey

Doctoral Dissertations

The field of proteomics encompasses the study of identities, interactions, and dynamics of all proteins expressed by a living system. Research in this dissertation blends biochemical and quantitative proteomics techniques to increase the latitude of biological applications for the bottom-up mass spectrometry proteomics approach. Together, isolation of selected protein “targets,” such as multiprotein complexes, and quantitative characterization yields information essential for more detailed understanding of microbial cell function.

Often, a challenging aspect of characterizing a variety of biochemically enriched samples is limited protein yield. This dissertation describes an enzymatic proteolysis protocol employing an organic/aqueous solvent that alleviates excessive handling steps …

Genetic Variation Within The Daphnia Pulex Genome, Abraham Eaton Tucker

Doctoral Dissertations

Genetic variation within the diploid Daphnia pulex genome was examined using a high quality de novo assembly and shotgun reads from two distinct D. pulex clones. Patterns of variation and divergence at single nucleotides were examined in physical and functional regions of the genome using comparative assembly output and available annotations. Additionally, mitochondrial genomes of the same D. pulex clones were assembled and compared for patterns of divergence, and substitutional biases. Intron presence/absence polymorphisms were identified computationally and verified experimentally. Finally, gene duplicate demographics were examined for patterns of divergence and estimates of gene birth rates.

A System For Automating The Interpretation Of Analytical Ultracentrifuge Data, Bradley W. Langhorst

Doctoral Dissertations

In order to accelerate the development of knowledge about protein associations, further improvements to acquisition, sharing, and analysis of Analytical Ultracentrifugation (AU) data must be made. XML data formats have been defined to allow complete exchange of the information associated with an AU experiment. Extensible formats to record solution identity, instrument setup parameters, acquired data, and analysis of that data have been developed. A normalized relational database to allow storage and searching of this data has also been created. A computer program called PANDaS (Protein Association Network Data Server) was built to interact with any software conforming to the data …