Life Sciences Commons^™

Exploring The Interactions Between Sars-Cov-2 And Host Proteins., Sojan Shrestha

School of Biological Sciences: Dissertations, Theses, and Student Research

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current pandemic, Coronavirus Disease 2019 (COVID-19). SARS-CoV-2 is considered to be of zoonotic origin; it originated in non-human animals and was transmitted to humans. Since the early stage of the pandemic, however, the evidence of transmissions from humans to animals (reverse zoonoses) has been found in multiple animal species including mink, white-tailed deer, and pet and zoo animals. Furthermore, secondary zoonotic events of SARS-CoV-2, transmissions from animals to humans, have been also reported. It is suggested that non-human hosts can act as SARS-CoV-2 reservoirs where accumulated …

Discovering Novel Polyextremotolerant Fungi, And Determining Their Ecological Role Within The Biological Soil Crust Consortium, Erin Carr

School of Biological Sciences: Dissertations, Theses, and Student Research

The ecological niche of polyextremotolerant fungi within oligotrophic ecosystems such as biological soil crusts has not yet been determined. These fungi persist in locations where nutrients are depleted while simultaneously surrounded by autotrophic microbes such as algae and cyanobacteria. Yet it has not been shown that they are engaging in any exchange of nutrients the way lichens do. However, there is seemingly no other way for these fungi to obtain vital nutrients, such as carbon or nitrogen, other than from these microbes. Here we have isolated polyextremotolerant fungi from cold desert biological soil crusts which are a microbial biofilm that …

Methanogen Metabolic Flexibility, Sean Carr

School of Biological Sciences: Dissertations, Theses, and Student Research

Methanogens are obligately anaerobic archaea which produce methane as a byproduct of their respiration. They are found across a wide diversity of environments and play an important role in cycling carbon in anaerobic spaces and the removal of harmful fermentation byproducts which would otherwise inhibit other organisms. Methanogens subsist on low-energy substrates which requires them to utilize a highly efficient central metabolism which greatly favors respiratory byproducts over biomass. This metabolic strategy creates high substrate:product conversion ratios which is industrially relevant for the production of biomethane, but may also allow for the production of value-added commodities. Particularly of interest are …

Characterization Of Novel Chlorovirus Glycosyltransferases That Synthesize Atypical Glycans, Eric Noel

School of Biological Sciences: Dissertations, Theses, and Student Research

Giant dsDNA chloroviruses encode a diverse repertoire of glycosyltransferases (GTases) and methyltransferases (MTases) that biosynthesize unusual, methylated sugars independent of their host chlorella-like green algae prompting a reexamination of glycobiology systems. Unlike most other viruses, the prototype chlorovirus PBCV-1 encodes most, if not all, of the machinery required to glycosylate its major capsid protein (MCP). The structures of the four N-linked glycans do not resemble any other glycans in the three domains of life. Here, we investigated the potential involvement of chlorovirus- encoded putative GTases and MTases in glycosylation of the viral MCP. First, we aimed to generate site-directed …

Polerovirus Genomic Variation And Mechanisms Of Silencing Suppression By P0 Protein, Natalie Holste

School of Biological Sciences: Dissertations, Theses, and Student Research

The family Luteoviridae consists of three genera: Luteovirus, Enamovirus, and Polerovirus. The genus Polerovirus contains 32 virus species. All are transmitted by aphids and can infect a wide variety of crops from cereals and wheat to cucurbits and peppers. However, little is known about how this wide range of hosts and vectors developed. In poleroviruses, aphid transmission and virion formation is mediated by the coat protein read-through domain (CPRT) while silencing suppression and phloem limitation is mediated by Protein 0 (P0)—a protein unique to poleroviruses. P0 gives poleroviruses a great advantage amongst plant viruses and diversifies polerovirus species, but the …

Dgts Production As A Phosphate Starvation Response In The Human Fungal Pathogen Candida Albicans, Caleb Wehling

School of Biological Sciences: Dissertations, Theses, and Student Research

Betaine lipids are a class of membrane lipids with betaine head groups. Three betaine lipids are known - diacylglyceryltrimethylhomoserine (DGTS), diacylglycerylhydroxymethylalanine (DGTA), and diacylglycerylcarboxymethylcholine (DGCC). Betaine lipids are most common in algae, although DGTS, the most common betaine lipid, is also found in many bacteria and fungi. Organisms which produce betaine lipids (especially DGTS) often don’t produce phosphatidylcholine (PtdCho), and DGTS structure resembles PtdCho structure without any phosphorous, leading to the hypothesis that betaine lipids may substitute for phospholipids in some organisms. This has been confirmed by discoveries that some organisms are capable of switching their membrane composition from PtdCho …

Examination Of Contribution Of Pentose Catabolism To Molecular Hydrogen Formation By Targeted Disruption Of Arabinose Isomerase (Araa) In The Hyperthermophilic Bacterium, Thermotoga Maritima, Derrick White

School of Biological Sciences: Dissertations, Theses, and Student Research

Thermotoga maritima ferments a broad range of sugars to form acetate, carbon dioxide, traces of lactate and near theoretic yields of molecular hydrogen (H₂). In this organism, the catabolism of pentose sugars such as arabinose depends on the interaction between the pentose phosphate, Embden Myerhoff and Entner Doudoroff pathways. While values for H₂ yield have been determined using pentose supplemented complex media (CM) and predicted by metabolic pathway reconstruction, quantitative in vivo measurements derived from pathway elimination have not been reported reflecting the lack of a genetic method for the creation of targeted mutations. Here, a spontaneous …

Phytohormone Signaling In Chlorella Sorokiniana: Perspectives On The Evolution Of Plant Cell-To-Cell Signaling, Maya Khasin

School of Biological Sciences: Dissertations, Theses, and Student Research

Cell-to-cell communication is a key aspect of microbial physiology and population dynamics, and a cornerstone in understanding the evolution of multicellularity. Quorum sensing in bacteria is a canonical example of microbial cell-to-cell signaling, in which bacteria use small molecule signals in order to monitor their population size and modulate their physiology accordingly. We propose that the evolution of plant hormone signaling arose in unicellular green algae, analogously to quorum sensing in bacteria, and that the complexity of these pathways required the recruitment of increasingly specific enzymes to increasingly sophisticated gene networks throughout the course of phytohormone signaling evolution. Using Chlorella …

The Roles Of Biotin In Candida Albicans Physiology, Nur Ras Aini Ahmad Hussin

School of Biological Sciences: Dissertations, Theses, and Student Research

Due to the increased number of immunocompromised patients, infections by Candida albicans have significantly increased in recent years. C. albicans transition from yeast to germ tubes is an essential factor for virulence. In this study we noted that Lee's medium, commonly used to induce filamentation, contained 500-fold more biotin than needed for growth. Thus, we investigated the effects of excess biotin on growth rate and filamentation by C. albicans in different media. At 37 °C, excess biotin (4 µM) enhanced germ tube formation (GTF) ca. 10-fold in both Lee's medium and a defined glucose proline medium, and ca. 4-fold in …

Relationship Between Morphogenesis And Secretion In The Filamentous Fungus Aspergillus Nidulans, Lakshmi Preethi Yerra

School of Biological Sciences: Dissertations, Theses, and Student Research

Filamentous fungi have a long history in biotechnology for the production of food ingredients, pharmaceuticals and enzymes. The advancements made in recent years have earned filamentous fungi such as Aspergillus species a dominant place among microbial cell factories. Although the model fungus A. nidulans has been extensively studied, the genetic and regulatory networks that underlie morphogenesis and development have yet to be fully characterized. The Rho GTPases (Cdc42 and RacA) are one of the most important regulators of the morphogenetic processes among diverse eukaryotic organisms. Although the functions of these GTPases are relatively well-characterized, little is known about their downstream …

Characterization Of The Role Of Host And Dietary Factors In The Establishment Of Bacteria In The Gastrointestinal Tract, Janina A. Krumbeck

School of Biological Sciences: Dissertations, Theses, and Student Research

Probiotic bacteria and synbiotics are used as therapeutic and prophylactic agents. The majority of probiotic and synbiotic applications contain bacterial strains that are allochthonous to the human gastrointestinal (GI) tract. Accordingly, many bacterial strains do not survive digestion, or are not capable of persisting and competing the resident gut microbiota, and are therefore washed out of the GI tract shortly after the treatment is discontinued. This might reduce the health effects of these treatments. Therefore, research is needed to address the ecological challenges that probiotic strains encounter in the GI tract in order to develop probiotic regimens. Determining which ecological …

Sequencing And Comparative Analysis Of De Novo Genome Assemblies Of Streptomyces Aureofaciens Atcc 10762, Julien S. Gradnigo

School of Biological Sciences: Dissertations, Theses, and Student Research

Streptomyces aureofaciens is a Gram-positive Actinomycete used for commercial antibiotic production. Although it has been the subject of many biochemical studies, no public genome resource was available prior to this project. To address this need, the genome of S. aureofaciens ATCC 10762 was sequenced using a combination of sequencing platforms (Illumina and 454-shotgun). Multiple de novo assembly methods (SGA, IDBA, Trinity, SOAPdenovo2, MIRA, Velvet and SPAdes) as well as combinations of these methods were assessed to determine which provided the most robust assembly. Combination strategies led to a consistent overestimation of the total genome size. Empirical data from targeted PCR …

No Nonsense: The Protection Of Wild-Type Mrnas From Nonsense-Mediated Mrna Decay In Saccharomyces Cerevisiae, Krista Patefield

School of Biological Sciences: Dissertations, Theses, and Student Research

Gene regulation in eukaryotes is tightly controlled at multiple levels to ensure proper expression and cellular homeostasis. Misregulation of gene expression is a common source of genetic disease. One mechanism by which cells are able to control gene expression is through the synthesis and degradation of the mRNA molecules encoding the genes. The transcription and degradation of mRNA molecules controls the pool mRNAs that are available to the translational machinery. One of the well-studied mRNA decay pathways is the Nonsense-Mediated mRNA Decay pathway (NMD). Originally, NMD was discovered as a posttranscriptional mRNA surveillance mechanism responsible for the deadenylation-independent decapping and …

Identification And Characterization Of Ion Channel Activity Of The M2 Protein From Influenza Virus D (Dm2), Jianing Liu

School of Biological Sciences: Dissertations, Theses, and Student Research

Viral ion channels are membrane proteins of influenza viruses that play essential roles in the replication cycle, which enables them to be targeted by antiviral drugs. M2 of influenza type A virus, BM2 of influenza type B virus, and CM2 from influenza type C virus have been characterized as ion channel proteins and antiviral drug amantadine was developed to control influenza type A virus. However, few studies have been conducted to clarify the properties of the M2 protein (DM2) of influenza type D virus, a novel influenza virus genus identified in 2014. To identify the ion channel activity of DM2, …

Expansion Of The Chlorovirus Genus By Studies On Virus Natural History And Chlorella Host Metabolism, Cristian F. Quispe

School of Biological Sciences: Dissertations, Theses, and Student Research

Inland waters cover about 2.5 percent of our planet and harbor huge numbers of known and unknown microorganisms including viruses. Viruses likely play dynamic, albeit largely undocumented roles in regulating microbial communities and in recycling nutrients in the ecosystem. Phycodnaviruses are a genetically diverse, yet morphologically similar, group of large dsDNA-containing viruses (160- to 560-kb) that inhabit aquatic environments. Members of the genus Chlorovirus are common in freshwater. They replicate in eukaryotic, single-celled, chlorella-like green algae that normally exist as endosymbionts of protists in nature. Very little is known about the natural history of the chloroviruses and how they achieve …

Kaposi’S Sarcoma-Associated Herpesvirus Transmission And Infection Among Young Zambian Children, Landon Olp

School of Biological Sciences: Dissertations, Theses, and Student Research

Kaposi’s sarcoma-associated herpesvirus (KSHV) is the etiologic agent for all forms of Kaposi’s sarcoma (KS)—one of the most common pediatric cancers in sub-Saharan Africa during the AIDS epidemic. KS was endemic in sub-Saharan Africa prior to the HIV/AIDS epidemic, but KS cases drastically increased thereafter. Our laboratory previously observed that KSHV infection is common among Zambian children and saliva is the major route of transmission. However, additional factors associated with the transmission of KSHV to children are poorly understood. Since a vaccine against KSHV is not currently available, it is paramount to understand factors associated with transmission so that alternative …

The Role Of The N-Terminus On The Enzymatic Activity Of Dutpase From Dictyostelium Discoideum, Kyle C. Varon

School of Biological Sciences: Dissertations, Theses, and Student Research

The enzyme deoxyuridine triphosphatase (dUTPase) (EC 3.6.1.23) converts dUTP to dUMP, thus shifting the dUTP to dUMP ratio in the cell. The molecule dUTP is subject to mis-incorporation into DNA due to lack of distinguishing by DNA polymerase. Uracil incorporation can be repaired with base excision repair mechanisms but may create overwhelming DNA strand breaks proving to be detrimental to the cell. Most dUTPases of eukaryotes are homotrimeric and contain five highly conserved motifs responsible for catalysis and substrate binding. Many dUTPases of eukaryotes possess a leading and core region in their sequence. The core region is composed of the …

Chlorovirus Skp1 And Core Ankyrin-Repeat Protein Interplay And Mimicry Of Cellular Ubiquitin Ligase Machinery, Eric Andrew Noel

School of Biological Sciences: Dissertations, Theses, and Student Research

The ubiquitin-proteasome system is a common target of several unrelated viruses that have evolved convergent strategies to redirect host ubiquitin machinery to serve their own needs. Members of the genus Chlorovirus, a group of large dsDNA viruses that infect certain freshwater chlorella-like green algae, encode a conserved Skp1 homolog and ankyrin-repeat (ANK) proteins, some of which contain C-terminal domains characteristic of cellular F-boxes or related viral PRANC domains. These observations suggested that this unique combination of chlorovirus proteins either interact with or imitate the key components of the SCF (Skp1-Cul1-F-box) ubiquitin ligases. Using mass spectrometry, we identified two functional …

Biosorption Of Heavy Metals Onto The Surface Of Bacteriophage T4, Zheng Huan Tan

School of Biological Sciences: Dissertations, Theses, and Student Research

Biosorption of heavy metals by bacterial and eukaryotic cell surfaces and the subsequent transport in aqueous environments is well recognized. However, very little is known about the roles viruses play in biosorption. Viruses outnumber prokaryotes and eukaryotes in environmental systems. These organisms represent abundant nanoparticulate organic colloids with reactive surfaces. Here we conducted a series of experiments to assess the biosorption potential of Escherichia coli bacteriophage T4. Adsorption of a heavy metal, Zn²⁺, to the surface of phage T4 was tested in a series of purified phage/metal solutions (0 µM – 1000 µM at 23°C). The Langmuir isotherm …

Functional Implications Of The Baf-B1 Axis During The Vaccinia Virus Life Cycle, Nouhou Ibrahim

School of Biological Sciences: Dissertations, Theses, and Student Research

Vaccinia virus is the prototypic member of the Poxviridae family, which includes variola virus, the agent of smallpox. Poxviruses encode their own transcriptional machinery and a set of proteins to evade the host defense system, and thus are able to replicate entirely in the cytoplasm of their host. The poxvirus life cycle occurs in sequential stages: early gene expression, DNA replication, intermediate gene expression and then late gene expression and morphogenesis. The temporally staged poxvirus life cycle makes viral DNA replication a required event for post-replicative events to occur. However, viral DNA replication itself depends on an early viral Ser/Thr …

Coccidia Of Gerbils From Mongolia, Ethan T. Jensen

School of Biological Sciences: Dissertations, Theses, and Student Research

In this study, gerbils collected in the Mongolia over the summers of 2009-2012 were examined for coccidia. In total, 171 gerbils of three species from 22 localities were examined for coccidia. Coccidian oocysts were identified from 21 gerbils, but those found in 1 of those gerbils were probably pseudoparasites of the host from which they were recovered. From the remaining 20 gerbils, 7 morphotypes of Eimeria and 1 morphotype of Isospora were identified. Four of the 7 morphotypes of Eimeria were attributed to new species which were described in this study. In addition, 10 previously described species of Eimeria were …

Analysis Of Human Papillomavirus Capsid Proteins: Insights Into Capsid Assembly, Willie A. Hughes

School of Biological Sciences: Dissertations, Theses, and Student Research

Abstract:

Papillomaviruses (PVs) are double stranded (ds)-DNA viruses (~8-kbp), which infect mucosal and cutaneous epithelial cells from various mammalian species, causing tumors in both epithelial cell-types. During the late-phase, the capsid proteins (L1 and L2), are expressed to encapsidate the viral genome generating infectious virion particles required for PV. Natural PV infections produce morphologically homogenous progeny virions 55-nm in diameter. Transient transfection systems allow individual expression of the capsid proteins, which are able to produce low-levels of infectious virion-like particles (VLPs) and non-infectious VLPs that have the capacity to resemble and function as wild-type virions.

Results: The research herein …

Evolution Of Human Immunodeficiency Virus Type 1 Clade C Envelope V1-V5 Region During Disease Progression In Non-Human Primate Model, For Yue Tso

School of Biological Sciences: Dissertations, Theses, and Student Research

Human immunodeficiency virus type 1 (HIV-1) clade C strain is the fastest spreading HIV-1 strain globally, especially in Africa. It has been decades since the acquired immune deficiency syndrome (AIDS) pandemic first started. However, an effective anti-HIV-1 vaccine is not yet available, which is partly due to the highly variable nature of HIV-1 envelope gene and the absence of a suitable animal model. Strengthening of the understanding of envelope evolution during disease progression will contribute significantly towards future anti-HIV-1 treatment and preventions.
Non-human primates have been an essential animal model for many biomedical research areas. Using simian-human immunodeficiency virus (SHIV) …

Telomere-Related Factors And Human Papillomavirus Genome Maintenance, Adam Rogers

School of Biological Sciences: Dissertations, Theses, and Student Research

Human papillomaviruses (HPVs) are small DNA tumor viruses identified by their characteristic ability to replicate as a nuclear plasmid in mitotically active basal keratinocytes. A key characteristic of the HPV life cycle is the establishment of a stable maintenance phase wherein the virus replicates at low copy number, which likely occurs in cells expressing little to no E1 and E2. It is thought that HPV16 replicates in a once-per-cell-cycle manner during this portion of its life cycle and presumably interacts with host chromosome replication and maintenance factors to facilitate this replication. The adaptive radiation of papillomaviruses in response to changing …

Small Interfering Rna-Mediated Translation Repression Alters Ribosome Sensitivity To Inhibition By Cycloheximide In Chlamydomonas Reinhardtii, Xinrong Ma

School of Biological Sciences: Dissertations, Theses, and Student Research

RNA interference (RNAi) is an evolutionarily conserved gene silencing mechanism in eukaryotes, with regulatory roles in a variety of biological processes, including cell cycle, cell differentiation, physiological and metabolic pathways, and stress responses. RNAi can function by transcriptional silencing, mRNA target cleavage, translation repression and/or DNA elimination. In this study, we used the unicellular green alga Chlamydomonas reinhardtii as a model system to study RNAi-mediated translation repression. We demonstrated that small RNAs (sRNAs) generated from exogenously introduced inverted repeat transgenes, with perfect complementarity to the 3’UTR of a target transcript, can inhibit protein synthesis, without or with only minimal mRNA …

Transcriptional Analysis Of Cervical Epithelial Cell Responses To Hiv-1, Andrew A. Block

School of Biological Sciences: Dissertations, Theses, and Student Research

Human Immunodeficiency Virus type 1 (HIV-1) infection causes a growing pandemic throughout the world, of which women comprise 51% of people who live with HIV-1, more than 60% in sub-Saharan Africa. HIV-1 infections of women are mainly acquired through female reproductive tract where cervical and vaginal epithelial cells are the first line of defense. Although HIV-1 does not directly infect epithelial cells, HIV-1 obligatorily interacts with and crosses over epithelial layer to infect susceptible target cells, mainly CD4+ T cells, in the lamina propria to initiate an infection. However, the mechanism and ramification of the interaction of HIV-1 and epithelial …

Characterization Of Binding And Fusion Efficiencies Mediated By The V1-V5 Env Derived From Transmitted And Non-Transmitted Viruses Isolated From A Perinatal Transmission Cohort From Zambia, Mackenzie Waltke

School of Biological Sciences: Dissertations, Theses, and Student Research

Human Immunodeficiency Virus Type 1 (HIV-1) is the etiological agent of acquired immunodeficiency syndrome (AIDS), which affects over 34 million people worldwide. In sub-Saharan Africa where access to antiretroviral therapies (ART) is limited, mother-to-child transmission (MTCT) rates remain high and represent a major concern in the global HIV/AIDS epidemic. Little is known about the biological properties of viruses that are transmitted perinatally, including how the biological functions of envelope (Env) influence transmissibility. Previously, transmitted viruses were found to have an advantage in replicative fitness mediated by Env V1-V5. In this study viruses derived from transmitting mother infant pairs (MIPs) were …

The Pseudomonas Syringae Type Iii Secretion System: The Translocator Proteins, Their Secretion, And The Restriction Of Translocation By The Plant Immune System, Emerson Crabill

School of Biological Sciences: Dissertations, Theses, and Student Research

Pseudomonas syringae is a Gram-negative plant pathogen whose virulence is dependent upon its type III secretion system (T3SS), a nanosyringe that facilitates translocation, or injection, of type III effector (T3E) proteins into eukaryotic cells. The primary function of P. syringae T3E proteins is suppression of plant immunity. Bacterial proteins called translocators form a translocon that forms a pore in the host plasma membrane which is traversed by T3Es. HrpK1, a putative P. syringae translocator, is a type III-secreted protein important for virulence and T3E injection, but not secretion of T3Es. Harpins are a group of proteins specific to plant pathogens …

Analysis Of Turnip Crinkle Virus Effects On The Innate And Adaptive Immunity In Arabidopsis Thaliana, Teresa J. Donze

School of Biological Sciences: Dissertations, Theses, and Student Research

The ability to understand the interactions between plants and the variety of pathogens they encounter on a daily basis is an important area of research. In the following work presented in this dissertation, I sought to better understand the mechanisms that Turnip crinkle virus (TCV) employs to elude the defense responses of the host plant Arabidopsis thaliana. It was previously determined that TCV coat protein (CP) interacts with a transcription factor, TIP, within the about 10 amino acid region near the N-terminus of the CP called the R-domain. When this interaction was disrupted by making single amino acid substitutions …

The Role Of Human Ubc9 During The Human Immunodeficiency Virus Replication Cycle, Christopher R. Bohl

School of Biological Sciences: Dissertations, Theses, and Student Research

Human immunodeficiency virus type 1 (HIV-1) is a retrovirus and the causative agent of the acquired immune deficiency syndrome (AIDS) pandemic. The retrovirus replication cycle is divided into early infectious events, which involve the infection and integration of the viral DNA into target cell chromosomes; and late events, which involve the expression of viral genes and assembly of infectious virions. To complete the replication cycle, HIV-1 utilizes various cellular pathways.

We identified the Ubc9 E2 SUMO conjugating enzyme as a HIV-1 Gag interaction partner. When this interaction was disrupted in HIV-1 producer cells by Ubc9 siRNA, the virus that was …