Organisms Commons^™

Modeling Fecal Bacteria In Oregon Coastal Streams Using Spatially Explicit Watershed Characteristics, Paul Bryce Pettus

Dissertations and Theses

Pathogens, such as Escherichia coli and fecal coliforms, are causing the majority of water quality impairments in U.S., making up ~87% of this grouping's violations. Predicting and characterizing source, transport processes, and microbial survival rates is extremely challenging, due to the dynamic nature of each of these components. This research built upon current analytical methods that are used as exploratory tools to predict pathogen indicator counts across regional scales. Using a series of non-parametric methodologies, with spatially explicit predictors, 6657 samples from non-estuarine lotic streams were analyzed to make generalized predictions of regional water quality. 532 frequently sampled sites in …

Regulation Of Hyaluronate Lyase (Hyla) Expression By Regr A Transcriptional Repressor In Streptococcus Pyogenes, Alexis A. Kordis

Biological Sciences Theses & Dissertations

Streptococcus pyogenes, group A streptococci (GAS), causes diseases ranging from asymptomatic to life threatening. Some strains of S. pyogenes produce extracellular hyaluronate lyase (HylA), a potential virulence factor. HylA is an enzyme that degrades hyaluronic acid, which is found in the extracellular matrix of human tissues. The breakdown of the host tissue contributes to the spread of infection. The hylA gene is not constitutively expressed in vitro, which implies regulation.

A proposed regulator of hyaluronate lyase expression is RegR, a LacI/GalR like protein. A vector containing disrupted regR was electro-transformed into S. pyogenes M-type 22 strain 10403. Growth characteristics …

Characterization Of Staphylococcus Aureus Lipase, Vithooshan Vijayakumaran

Electronic Thesis and Dissertation Repository

USA300, a strain of community-associated methicillin resistant Staphylococcus aureus (CA-MRSA), has become prevalent in the community. Colonization of human skin requires mechanisms that allow this bacterium to overcome the innate immune defenses on the skin, including secretion of antimicrobial lipids. Antimicrobial lipids inhibit S. aureus growth and induce the staphylococcal proteolytic cascade, producing aureolysin (Aur) which processes the lipase glycerol ester hydrolase (Geh). Nearly all S. aureus strains secrete Geh, yet little information exists concerning its function. Using purified Aur and Geh we confirm that aureolysin processes proGeh to Geh. We then confirmed that geh was required for lipase activity …

Regulating Rsma Expression In Pseudomonas Aeruginosa, Sean D. Stacey

Electronic Theses and Dissertations

Pseudomonas aeruginosa, a Gram-negative bacillus, commonly infects immunocompromised individuals and uses a variety of virulence factors to persist in these hosts. The posttranscriptional regulator, RsmA, plays a role in the expression of many virulence factors in P. aeruginosa. RsmA up regulates virulence factors used in colonizing hosts. However, regulation of rsmA is not well elucidated. Transposon mutagenesis was performed on P. aeruginosa containing a transcriptional rsmA-lacZ fusion to answer this question. Mutants were screened via β-galactosidase assay and transposon insertions identified via arbitrary PCR. A probable MFS transporter, we named mtpX, was one significant transposon mutant identified. …

Systematic Assessment Of The Contribution Of Superantigens To Nasopharyngeal Colonization In A Mouse Model Of Streptococcal Infection, Katherine J. Kasper

Electronic Thesis and Dissertation Repository

Streptococcus pyogenes is adapted for persistence in humans. It typically colonizes the tonsils and skin, and humans are the only known reservoir. S. pyogenes can cause a wide range of mild to serious infections. Most streptococci-related deaths are due to complications of rheumatic fever and invasive infections. S. pyogenes produces virulence factors that contribute to the pathogen’s ability to colonize and cause disease, including streptococcal superantigens (SAgs), also known as streptococcal pyrogenic exotoxins (Spes). SAgs function by cross-linking T cells and antigen presenting cells (APC) which may cause a massive inflammatory response, and as such have been found to contribute …