<p>Department not listed. Molecular Biology</p> / <p>The yeast S. cerevisiae Is able to use several different metabolic pathways for the generation of metabolic energy, and is able to vary the synthesis of these multlenzyme systems in response to changes in the external environment. The responses of the yeast to various changes in the environment have been studied and correlated with changes in the rate of synthesis of various enzymes. Two of these pathways are found in the mitochondrion, a sub-cellular organelle, the structural integrity of which is necessary for the functioning of these integrated systems. The experiments described thus provide information about the control of structure and function in cellular organelles, as well as about the general changes in energy metabolism.</p> / Doctor of Philosophy (PhD)

No description available.

This study investigated the connection between Body Dissatisfaction and Drive for Thinness to several psychological correlates: Ineffectiveness, Interpersonal Distrust, Perfectionism, Interoceptive Awareness, and Maturity Fears. Regression analyses indicated that these five correlates together accounted for 23% of the variance in a measure of Body Dissatisfaction. Body Dissatisfaction and the five correlates together accounted for 52% of the variance in a measure of Drive for Thinness. Results of the path analysis confirmed that Ineffectiveness, Interoceptive Awareness and Maturity Fears were the strongest predictors of Body Dissatisfaction. In turn, Body Dissatisfaction, Ineffectiveness and Interoceptive Awareness were the strongest predictors of Drive for Thinness. Gender differences and prevalence rates of eating disordered behavior were reviewed. Consistent with other research, this study confirmed high levels of bingeing and purging behavior (44%) among college men and women. / Ph. D.

The growing popularity of farmers' markets coupled with a high percentage of produce-related foodborne outbreaks highlights the need for an emphasis on food safety within these markets to protect farmers, patrons and local economies. The number of farmers' markets registered in the United States has almost tripled in the last 15 years. Fresh produce constitutes the majority of food sold at farmers'markets. Between 1998 and 2008, raw produce accounted for almost half of the 4,589 foodborne illness outbreaks linked to a specific commodity. This research was conducted to identify practices at farmers' markets which may contribute to an increased risk of contamination, assess the microbial quality of produce sold at farmers' markets, as well as to develop a food safety management plan template for market managers to utilize to build their own food safety plan. Using an observational data collection method, risky food safety practices were identified at Southwest Virginia farmers' markets. While market managers and vendors in three of the five markets observed had formal food safety training, numerous risky food safety behaviors were still observed including temperature abuse, cross contamination opportunities, and poor personal hygiene and sanitation. Additionally, the microbial quality of produce from Southwest Virginia farmers' markets was compared to produce sold at retail using culture based microbiological plating and molecular methods. Total aerobic bacteria and coliforms were enumerated, and the presence of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and generic E. coli were determined. A significantly greater quantity of total aerobic bacteria was isolated from farmers' market leafy greens, onions and tomatoes when compared to a retail grocery store (P=0.0011, P=0.0395, and P<0.0001, respectively). Additionally, one or more target pathogen was isolated from 28 farmers' market samples and 16 retail grocery store samples. The observed risky food safety behaviors along with the bacterial data collected emphasize the need for a pathogen reduction focus on fresh produce not only at farmers' markets, but also with growers and other retail outlets. To help promote proper food safety practices at farmers' markets, a farmers' market food safety management plan (FSMP) template was developed to address the top five risk factors contributing to foodborne illness as identified by the Centers for Disease Control and Prevention (CDC). The FSMP was evaluated for practicality and feasibility through interviews with market mangers in North Carolina and Virginia. Most market managers (66.7%) agreed that the FSMP was practical for their market while only 33.3% agreed that they could implement the plan immediately. Revisions suggested to the FSMP will be made and it will be made available in Virginia and North Carolina in spring 2016. / Ph. D.

yes / The outbreak of Ebola in West Africa in 2014 has underlined the risks posed by outbreaks of highly virulent and deadly diseases, whether caused naturally, accidentally or deliberately. It also emphasised the responsibility of all those engaged in the life sciences, whether in government, industry or academia, to ensure that research is done safely and securely. This book, Preventing Biological Threats, is intended to raise awareness and knowledge of biological security of everyone active in the life sciences, ranging from those engaged in research to those engaged in management and policy-making, both nationally and internationally. The advances in biotechnology over the past decades and in the future have brought and will bring significant benefits to humankind, animals and plants -- however, these advances also bring risks that we need to be aware of and ensure that they cause no harm. The continuing debate about the potential danger of carrying out ‘Gain-of-Function’ experiments with highly pathogenic viruses such as avian influenza has brought the problem of biological security to the attention of many within but also beyond the life science community. It also has left some of them wondering what biological security is and how it can be incorporated into the life sciences. What steps should be taken to ensure that these and other dual use research activities are not misused? It is being increasingly recognised that biosecurity and biosafety are not only relevant to activities within a laboratory, but also extend to the effects that these activities can have outside the laboratory if they result in accidental outbreaks of diseases in humans, animals or plants. The international basis for the prevention of the hostile misuse of life sciences is the Biological and Toxin Weapons Convention which this year, on 26 March 2015, has been in force for forty years. The Convention was the first treaty to prohibit the development and possession of an entire category of weapons. At this moment 173 States Parties have ratified the Convention (and the Convention has a further 9 Signatories). At the Seventh Review Conference of the Biological and Toxin Weapons Convention in 2011, of which I was President, the States Parties agreed on the need for all those engaged in the life sciences to be involved as key stakeholders in the protection of their work from hostile misuse, and therefore on the importance of broad biosecurity education. This book with its 21 chapters addresses the need for biosecurity education, in six sections on the history of threats and responses; scientists, organisations and biosecurity; biosecurity and law enforcement; states and biosecurity; and biosecurity and active learning. It is a significant and welcome step forward both in its integrated content and the active learning focus in the associated Team Based Learning exercises. I am convinced that this approach will help all those engaged in the life sciences - in government, industry or academia – to become more aware of biosecurity and of their responsibilities for it. It is therefore a great pleasure to commend the authors and editors for their work and the Governments of Canada, Jordan and the United Kingdom for their funding and involvement in the production of this book under the Global Partnership. Ambassador Paul van den IJssel

SARS-CoV-2 is caused by a pathogenic and highly transmissible beta coronavirus leading to severe infections in immuno-compromised individuals. This study first evaluates the primers used in the Reverse Transcription Polymerase Chain Reaction (RT-PCR) to detect SARS-CoV-2 by understanding how mutations might affect the primer efficiency with the SARS-CoV-2 sequences. Mutations on the Spike protein of SARS-CoV-2 are the most important as the spike protein mediates the viral entry into host cells. This study tracks the course of mutations on the spike protein by focusing on the haplogroups of the sequences across the world. A comprehensive database linking three important, currently available databases is curated as part of this study to fill the gaps caused by sequencing errors. Further, this study exploits the data generated by the Illumina and Oxford Nanopore next generation sequencing methods to study the evolution of mutations in a single Septuagenarian patient over an infection period of 102 days using the gene analysis software Geneious Prime. / Master of Science / A novel corona virus named Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) has taken down the entire world by causing Covid-19 pandemic. Initially detected in Wuhan, China, the virus has now made its way to more than 200 countries with a heavy death toll. Understanding the virus through mutation tracking and improving diagnostics and vaccine design have now become the top priority of researchers. Most of these researchers depend on quality viral sequence datasets to identify and track mutations. One aim of this study is to provide a comprehensive dataset linking the GISAID (Global Initiative on Sharing All Influenza Data), NCBI (National Center for Biological Information) and the SRA (Sequence Read Archive) sequences. The dataset can be used for genome analysis and mutation tracking which can provide important insights for vaccine design and in improving diagnostic assays. In addition, this study provides an analysis of viral mutations in in the genomic regions targeted by commonly used primers in the RT-PCR tests for SARS-CoV-2 that may affect the efficiency of detection. This study also uses the haplogroup information of people across the world to track the D614G mutation on the S gene of SARS-CoV-2 as it may be associated with increased transmissibility. To track the course of mutations in SARS-CoV-2, it is important to analyze the sequencing data provided by the Illumina and Oxford Nanopore next generation sequencing methods. We present a case study to investigate the course of SARS-CoV-2 mutations in a single septuagenarian patient over a period of 102days using the Sequence Read Archive (SRA) data generated by two Next Generation Sequencing methods and compare the advantages that one has over the other.

The bacterial flagellum is a rotary motor that propels motile bacteria through their surroundings via swimming motility, or on surfaces via swarming motility. The flagellum is a key virulence factor for motile pathogenic bacteria. Viruses that infect bacteria via this appendage are known as flagellotropic or flagellum-dependent bacteriophages. Much like other phages, flagellotropic phages are of interest for clinical applications as antibacterial agents, particularly against multidrug resistant (MDR) bacteria. Bacteriophage χ is a flagellotropic phage that infects multiple species of motile pathogens. In the projects described below, we characterized several aspects of the complex interactions between χ and two of its hosts: Salmonella enterica and Serratia marcescens. In Chapter I, we describe in detail the existing knowledge on flagellum-dependent bacteriophages, pathogenic bacteria, and the flagellar motility system. We also expand significantly on flagellotropic phage χ. In Chapter II, we describe our discovery of S. enterica cellular components other than motility that are crucial for bacteriophage χ infection, making the key discovery that the AcrABZ-TolC multi-drug efflux system is required for infection to proceed. We additionally found that the host molecular chaperone trigger factor is important for the χ phage lifecycle. In Chapter III, we outline our characterization of the initial binding interaction between χ and the flagellum, determining that of flagellin's seven domains, C-terminal domain D2 is the most important for χ adsorption. In Chapter IV, we expand on this by discussing our work that determined that the χ tail fiber protein is encoded by the gene CHI_31, purification of this recombinantly-expressed protein, and demonstration of its direct interaction with the flagellar filament. Lastly, in Chapter V, our findings indicate that S. marcescens is able to detect χ infection and lysis in the surroundings and alter gene expression, resulting in an increase in the production of the red pigment prodigiosin. Overall, our hypothetical model for χ infection is as follows: χ binds to the flagellum of its host using its single tail fiber, composed of monomers of the CHI_31 gene product gp31. This tail fiber interacts with CTD2 of flagellin, and the rotation of the flagellum brings the phage to the cell surface, where it interacts with AcrABZ-TolC to inject its genetic material into the host cytoplasm. At some point during the process of production of phage particles and subsequent cell lysis, the host molecular chaperone trigger factor likely assists with proper folding of χ proteins. After cell lysis, cells in the surroundings are capable of detecting lysis and responding accordingly, at least in the case of S. marcescens. This research is clinically relevant for a number of reasons. Phage therapy, the use of bacteriophages as antibacterial agents, requires knowledge of phage infection pathways for optimal implementation. The fact that the flagellum and a complex mediating MDR are both essential for χ infection leads to particular interest in χ for this application. Knowledge of the host-determining factors between χ and Salmonella may lead to the ability to alter the χ phage genome to target specific pathogenic Salmonella or Escherichia coli strains while avoiding disruption of beneficial bacterial communities. / Doctor of Philosophy / Bacteriophages (phages) are viruses that only infect bacteria. They do not harm animal cells or the human body, despite being highly effective predators of bacteria. As such, they have applications in the medical field as antibacterial agents, similar to antibiotics. Phages that infect pathogenic bacteria like Salmonella are of particular interest for scientific research. Bacteriophage χ (Chi) infects bacteria by binding to their flagella, propeller-like appendages that a bacterial cell uses to swim through its surroundings. In many bacterial species, flagella and the ability to swim are closely involved in human infection. Due to this, flagellotropic (flagellum-dependent) phages like χ may be particularly useful as antibiotics. Throughout this project, we characterized the χ phage infection process, including exploring how it attaches to flagella, interactions it has on the surface of and inside Salmonella cells, and the largely unexplored relationship with Serratia marcescens, another bacterial species that causes illness in humans and is highly antibiotic resistant. Overall, our research contributes to the medical field, and indicates that χ may serve as a highly effective antibacterial treatment.

A silent pandemic, chronic, non-healing wounds are a major cause of morbidity, with treatment and management representing significant health burdens. The opportunistic pathogens Staphylococcus aureus and Pseudomonas aeruginosa are the most common species isolated from chronic wounds. Polydimethylsiloxane (PDMS), a biocompatible and, inexpensive to fabricate polymer, can undergo various modifications. The ability of the produced polymers to attract S. aureus and P. aeruginosa, either from the planktonic state, or while sessile in biofilms on ex vivo skin, was investigated using flat (FL) or patterned (PT) PDMS with or without 1% or 10% triclosan Patterned PDMS + 10% triclosan (PT 10%) attracted significantly more live S. aureus and P. aeruginosa, as determined using Colony Forming Unit (CFU) analysis (*p<0.01), Scanning Electron Microscopy (SEM) (*p<0.01) and Confocal Scanning Laser Microscopy (CSLM) (*p<0.01). The released triclosan was not cytotoxic against either bacteria or primary cultures of human dermal fibroblasts using Water Soluble Tetrazolium Salts (WST-1) assay. High performance liquid chromatography analysis highlights low level of triclosan release from the PDMS. Bacterial infection in co-culture using the Boyden chamber assay increased fibroblast viability in the presence of PDMS (*p<0.05). PT 10% demonstrated superior biofilm transfer from epidermis (*p<0.05), in comparison to all other analysed polymers. In summary, the unique topography of PDMS combined with triclosan attracted bacteria most efficiently. This promising data suggests potential for engineering a patterned polymer to physically transfer biofilms from wounds, and importantly lacks bactericidal properties which is vital in the quest to combat antimicrobial resistance.

Thesis (M. Tech.(Biomedical Technology)) - Central University of technology, Free State, 2011 / The existence of geophagia from as early as 460 BC up to now, makes it relevant to investigate all aspects related to geophagia. Geophagia is a direct route for potential transmission of pathogens to the human host, through the ingestion of soil. Soil-borne diseases in humans are causing growing concern as sewage disposal, which involve sewage sludge and waste water drainage from these plants, is on the increase. It is estimated that approximately seven million tons of sewage sludge is produced annually and that 54% of this sewage sludge is introduced into soil. Data on enteric infection in humans caused by contamination from soil is limited and need further investigation. The aim of the study was, therefore, to collect information on the microbiological presence in geophagic soil in the Qwa-Qwa district. Objectives included the collecting of information regarding various sampling sites in the Qwa-Qwa district and also soil samples sold by vendors, investigation of the prevalence of known human pathogenic bacteria and fungi in geophagic soil, investigating the culturability of Salmonella enteritidis in geophagic soil in comparison with the viability of these organisms in soil for long periods of time, investigating potential antimicrobial activity of geophagic soil, as some of the geophagists are convinced that the geophagic soils have medicinal properties, and to determine the microbial diversity of geophagic soils, which can not be accomplished by conventional microbial culturing methods.

The thesis presents the development of functionalized electrospun nylon 6 nanofibers for the eradication of pathogenic microorganisms in drinking water. Imidazole derivatives were synthesized as the antimicrobial agents and were characterized by means of NMR spectroscopy, IR spectroscopy, elemental analysis and X-ray crystallography. The first set of compounds (2-substituted N-alkylimidazoles) consisted of imidazole derivatives substituted with different alkyl groups (methyl, ethyl, propyl, butyl, heptyl, octyl, decyl and benzyl) at the 1-position and various functional groups [carboxaldehyde (CHO), alcohol (CH2OH) and carboxylic acid (COOH)] at the 2-position. It was observed that the antimicrobial activity of the compounds increased with increasing alkyl chain length and decreasing pKa of the 2-substituent. It was also observed that the antimicrobial activity was predominantly against a Gram-positive bacterial strains [Staphylococcus aureus (MIC = 5-160 μg/mL) and Bacillus subtilis subsp. spizizenii (MIC = 5-20 μg/mL)], with the latter being the more susceptible. However, the compounds displayed poor antimicrobial activity against Gram-negative bacterial strain, E. coli (MIC = 150- >2500 μg/mL) and did not show any activity against the yeast, C. albicans. The second set of compounds consisted of the silver(I) complexes containing 2-hydroxymethyl-N-alkylimidazoles. The complexes displayed a broad spectrum antimicrobial activity towards the microorganisms that were tested and their activity [E. coli (MIC = 5-40 μg/mL), S. aureus (MIC = 20-80 μg/mL), Bacillus subtilis subsp. spizizenii (MIC = 5-40 μg/mL) and C. albicans (MIC = 40-80 μg/mL)] increased with the alkyl chain length of the 2-hydroxymethyl-N-alkylimidazole. The third set of compounds consisted of the vinylimidazoles containing the vinyl group either at the 1-position or at the 4- or 5- position. The imidazoles with the vinyl group at the 4- or 5-position contained the alkyl group (decyl) at the 1-position. For the fabrication of the antimicrobial nanofibers, the first two sets of imidazole derivatives (2-substituted N-alkylimidazoles and silver(I) complexes) were incorporated into electrospun nylon 6 nanofibers while the third set (2-substituted vinylimidazoles) was immobilized onto electrospun nylon 6 nanofibers employing the graft polymerization method. The antimicrobial nylon nanofibers were characterized by IR spectroscopy and SEM-EDAX (EDS). The electrospun nylon 6 nanofibers incorporated with 2-substituted N-alkylimidazoles displayed moderate to excellent levels of growth reduction against S. aureus (73.2-99.8 percent). For the electrospun nylon 6 nanofibers incorporated with silver(I) complexes, the levels of growth reduction were >99.99 percent, after the antimicrobial activity evaluation using the shake flask method. Furthermore, the grafted electrospun nylon 6 nanofibers showed excellent levels of growth reduction for E. coli (99.94-99.99 percent) and S. aureus (99.93-99.99 percent). The reusability results indicated that the grafted electrospun nylon 6 nanofibers maintained the antibacterial activity until the third cycle of useage. The cytotoxicity studies showed that grafted electrospun nylon 6 nanofibers possess lower cytotoxic effects on Chang liver cells with IC50 values in the range 23.48-26.81 μg/mL. The thesis demonstrated that the development of antimicrobial electrospun nanofibers, with potential for the eradication of pathogenic microoganisms in water, could be accomplished by incorporation as well as immobilization strategies.