Microbiology Commons^™

Vertical Transmission Of West Nile Virus In Culex Spp. Mosquitoes Of Clark County, Nevada, Vivek K. Raman

UNLV Theses, Dissertations, Professional Papers, and Capstones

West Nile Virus (WNV) is an RNA arbovirus that cycles between mosquitoes and birds, but also infects and causes disease in humans, horses and other vertebrate species. Although most infections are asymptomatic, WNV has emerged as the most common cause of epidemic meningoencephalitis in North America and the leading cause of arboviral encephalitis in the United States.

Mosquitoes of the genus Culex are the most active vectors of WNV in North America. Approximately 85% of human WNV infections in the United States occur in late summer with a peak number of cases in August and September. Vertical transmission is defined …

Transcriptional Regulation Of The Shigella Flexneri Icsp Promoter: Silencing And Anti-Silencing By H-Ns And Virb, Dustin Harrison

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shigella species are gram-negative intracellular pathogens that cause bacillary dysentery in humans. Many genes required for virulence of Shigella are carried on a large 230 kb plasmid and many of these are under the transcriptional control of the histone-like nucleoid structuring protein (H-NS) and by the major virulence regulator VirB. At the non-permissive temperature of 30⁰C, H-NS represses transcription, while at 37⁰C VirB alleviates this repression. This mechanism of gene regulation has been coined "silencing/anti-silencing" and is commonly found in many important bacterial pathogens including Salmonella spp. and Yersinia spp. The icsP gene, encoded by the Shigella virulence plasmid, is …

Bacillus Cereus And Bacillus Anthracis Germination Kinetics: A Michaelis-Menten Approach, Helen Luu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Bacillus species are rod-shaped, gram-positive bacteria that are capable of producing endospores. In this dormant stage, the endospores can persist in hostile physical and chemical environments. Once conditions become favorable, the spores germinate into actively dividing cells, vegetative cells. Germination is a crucial step for the pathogenicity of the Bacilli in affecting a host organism.

Our study applies mathematical approaches to spore germination to determine whether the binding of one germinant will affect the binding of another germinant. We pursued this approach with two different species, B. cereus and B. anthracis, both pathogenic organisms. B. cereus is a widely known …

The Role Of Transcription In Stationary Phase Mutagenesis In Bacillus Subtilis, Holly Anne Martin

UNLV Theses, Dissertations, Professional Papers, and Capstones

Stationary phase mutagenesis, also known as stress-induced or adaptive mutagenesis, is defined as the accumulation of mutations during conditions of no net growth or conditions of stress. This process has been implicated in acquiring antibiotic resistance and evasion of host immune responses in microbial pathogens and in the generation of mutations that lead to neoplasia in animal cells. Previous work has shown that defects in DNA synthesis and repair systems contribute to the formation of adaptive mutations; however the role of transcription in the accumulation of mutations is still being examined. It is speculated that transcriptional derepression leads to an …

An Evaluation Of Methicillin Resistant Staphylococcus Aureus Survival On Five Environmental Surfaces Under Two Different Humidities, With And Without The Addition Of Bovine Serum Albumin, Courtney Ann Coughenour

UNLV Theses, Dissertations, Professional Papers, and Capstones

The spread of antibiotic resistant bacteria is a major public health concern, as they result in greater healthcare costs and increased morbidity and mortality rates. Methicillin resistant Staphylococcus aureus (MRSA) is one organism of particular concern, with the number of infections increasing in epidemic proportion. Bacterial surface contamination with MRSA is significant, as it may serve as a reservoir for transmission and have negative health implications. The purpose of this study was to evaluate survival of MRSA on five environmental surface materials; glass, wood, vinyl, plastic, and cloth. The effect of relative humidity (RH) and bovine serum albumin (BSA) were …

Molecular Epidemiology Of Methicillin-Resistant Staphylococcus Aureus (Mrsa), Ilene Bautista

UNLV Theses, Dissertations, Professional Papers, and Capstones

Staphylococcus aureus is a frequent cause of a myriad of infections in hospitals, healthcare facilities and community settings. It is often related to skin and soft tissue infection, but it can also cause other diseases varying from food poisoning to endocarditis and toxic shock syndrome. According to a study by Kuehnert et al. (2006) there has been a strong association between Staphylococcus aureus (S. aureus) carriage and risk factors for subsequent infections. Subsequent infection from S. aureus , including methicillin-resistant S. aureus (MRSA) infection, can be projected by looking at the presence of S. aureus nasal colonization. The purpose of …

Identification Of Arid Soil Inducible Genes In Pseudomonas Fluorescens Strain Pf0-1, Katila Pipitone

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis contains three major sections: introduction, literature review and the project entitled: 'Identification of Arid Soil Inducible Genes in Pseudomonas fluorescens Strain Pf0-1'. The introduction section describes a general background, the current and potential applications of P. fluorescens and the main goal of this dissertation. The literature review chapter discusses two main areas. The first area offers insights about different types of in vivo expression technology (IVET) as a tool in gene identification. This section also describes the limitations of IVET, as well as the benefits over other methods for gene identification. The second part of the literature review …

The Influence Of Carbon Source Types And Nitrate On The Performance Of The Enhanced Biological Phosphorus Removal Systems, Shamim Ara Begum

UNLV Theses, Dissertations, Professional Papers, and Capstones

This research focuses on two issues in enhanced biological phosphorus removal (EBPR). The first issue encompasses the effect of the type of carbon sources (i.e. volatile fatty acids and non volatile fatty acids) on the microbiology of EBPR. The second issue deals with the influence of denitrification on EBPR. Few studies have been performed to investigate these two issues. The recent findings on these areas are summarized below to establish the knowledge gaps this dissertation attempted to address. Details on the specific findings can be found in the literature review portion of this proposal.

Protection Of Macrophages J774a.1 By Purine Nucleoside Analogues From Bacillus Anthracis Mediated Necrosis, Zadkiel R. Alvarez

UNLV Theses, Dissertations, Professional Papers, and Capstones

Eight years after the lamentable anthrax attacks, major scientific effort continues to be done, in order to stop imminent acts of bioterrorism. Innovative ways of therapy against the anthrax disease are being investigated. B. anthracis, the etiological agent of the infection, has a dormant stage in its life cycle known as the endospore. When conditions become favorable spores germinate, transforming into vegetative bacteria. In inhalational anthrax, the most fatal manifestation of the disease, spores enter the organism through the respiratory track, and are phagocytosized by alveolar macrophages of the lungs. Spores are able to sense nutrient availability, activating their germination …

Characterization Of Aerobic Respiration In Great Basin Hot Springs, Caitlin N. Murphy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Despite a wide diversity of possible electron donors available to fuel chemolithotrophy, it has been proposed that hydrogen is the single most important electron donor in geothermal ecosystems. To directly test this hypothesis, a simple system was devised to determine whether microorganisms in hot spring water and sediment are capable of using hydrogen and other electron donors for aerobic respiration using microrespirometry. The protocol for these experiments was developed using pure cultures of Thermocrinis ruber to determine the effect of growth conditions on the rate of oxygen consumption following the addition of electron donors. For field experiments, samples were collected …

Ventilation Rates For Carassius Auratus During Changes In Dissolved Oxygen, Collin Nolan

UNLV Theses, Dissertations, Professional Papers, and Capstones

This experiment was designed to determine whether dissolved oxygen concentrations would influence the ventilation rate of goldfish, Carassius auratus. Ventilation rate can be determined by counting opercular movements. Opercular movements of the same five goldfish were counted at three different levels of dissolved oxygen to determine whether there were differences in ventilation rates. Average ventilation rates were established for each of the three levels of dissolved oxygen and compared statistically. There were significant differences in the ventilation rates averages at each of the three levels. Carassius auratus will exhibit changes in ventilation rates when dissolved oxygen levels change.