Organisms Commons^™

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 …

Antimicrobial Activity Screening Of Recombinant And Synthetic Varasin A Defensin From The Hard Tick Dermacentor Variabilis Against Various Bacteria, Julia A. Sharp

Biological Sciences Theses & Dissertations

Hematophagous arthropods, such as ticks and mosquitoes, rely on their innate immune system for defense against pathogens ingested in a blood meal as well as those acquired through injury. In response to pathogen recognition, the production of antimicrobial peptides, such as defensin, is typically upregulated. Varisin, a defensin, is thought to be a key component in the immunocompetence of the hard tick D. variabilis against Borrelia burgdorferi, the causative agent of Lyme disease. To study the antimicrobial effects of varisin, recombinant varisin was expressed by both insect cells and E coli. Purification of the protein followed by enterokinase treatment yielded …

Characterization Of Spy1600 A Putative Hyaluronidase Gene In Group A Streptococci, Karin M. Berling

Biological Sciences Theses & Dissertations

Group A Streptococci (GAS), also known as Streptococcus pyogenes, can cause a variety of human diseases ranging from asymptomatic to life threatening. Exactly how a single type of organism is able to inflict such a multitude of diseases remains to be fully understood. One possibility includes the large number of secreted virulence factors expressed by the organism. The recent sequencing of three streptococcal genomes has indicated the existence of several previously unknown genes, some of which may encode possible virulence factors. Among these is Spy1600, which based on its sequence similarities has been proposed to encode a hyaluronidase, a …

Development Of An Electrotransformation Technique For Streptococcus Iniae And Preliminary Characterization Of The Hemolysin Associated With This Bacterium, Kimberly Ann Hahn

Biological Sciences Theses & Dissertations

Streptococcus iniae is a gram-positive organism responsible for causing disease in both freshwater as well as saltwater fish. Every year fisheries lose fish by the tons due to diseases caused by this organism. In 1991, the first reported human case of disease associated with this organism was described. Since this initial case, there have been numerous other reported cases of S. iniae infections. This organism is a catalase negative, facultatively anaerobic organism that produces a capsule and when plated onto blood agar demonstrates β-hemolytic activity.

In this study, the relationship between the hemolysin produced by S. iniae and the lactate …

Seasonal Phytoplankton Assemblages Of Five Ephemeral Ponds In York County, Virginia, Michelle R. Kokolis

Biological Sciences Theses & Dissertations

Five ephemeral ponds were identified in and around the Grafton Ponds Natural Area Preserve, approximately 56 km north of the City of Norfolk, Virginia. These ponds, which are filled seasonally by precipitation and groundwater discharge, range from 0.1 ha to 2 ha in size and from 4 cm to 3 meters in depth. Ponds for the study were chosen based on variations in their size, depth, basin cover material, canopy openness, and historical inundation period. The purpose of this study is to relate differences in the phytoplankton assemblages to the physical and chemical characteristics of the ponds. All five ponds …

A Comparison Of Phytoplankton Communities In Lake Prince And The Western Branch Reservoir, Suffolk, Virginia, Cara Marie Muscio

Biological Sciences Theses & Dissertations

Lake Prince and the Western Branch Reservoir are two eutrophic bodies of water located in Suffolk, Virginia. Lake Prince and its two small tributaries join the Western branch via a constructed spillway. This lake system is a source of water for the surrounding municipalities, and a recreational area for community citizens. In the past, these bodies of water had repeated incidents of low oxygen and nuisance algal blooms, particularly cyanobacteria species. As a result aerators have been installed in the main body of both Lake Prince and the Western Branch Reservoir. In addition, a pipeline has been installed from North …

Effect Of Magnesium On The Production Of Scna And Scnr By Streptococcus Pyogenes, Strain Ff22, Laura E. Quinn

Biological Sciences Theses & Dissertations

The lantibiotic SA-FF22, produced by Streptococcus pyogenes strain FF22, was the first described antimicrobial peptide produced by a Streptococcus species. S. pyogenes is a group A Streptococcus responsible for such human illness as strep-throat, rheumatic fever, necrotizing fasciitis, endocarditis, and meningitis. Previous studies of SA-FF22 have shown that antimicrobial activity is lost in the presence of lmM magnesium. We hypothesize that the lack of SA-FF22 activity in the presence of magnesium is due to an absence of transcription of scnA, the gene encoding SA-FF22. The lack of transcriptional activation of scnA may be due to an absence of ScnR, a …

Investigations Into The Innate Resistance Of The Tick, Dermacentor Variabilis, When Challenged With The Bacterium, Escherichia Coli, Shane Michael Ceraul

Biological Sciences Theses & Dissertations

In addition to the soluble response, many invertebrates control bacterial infections by means of phagocytosis or melanotic encapsulation. In some insects, Escherichia coli growth is reported to be inhibited by aggregation/encapsulation. Soluble and phagocytic responses to bacterial challenge have been reported in ticks, but evidence of an aggregation/encapsulation response was reported only for inanimate (araldite) implants. This study was done to determine how ticks control infection by E. coli. Ticks were challenged by direct inoculation of bacteria into the hemocoel cavity. Using plate counts, no viable E. coli were detected I hour post-inoculation. A direct fluorescence assay (DF A) …

An Extracellular Protein Produced By Staphylococcus Hominis Strain Αm With Antimicrobial Activity Against Mycobacterium Spp, Sandra May Jacobsen

Biological Sciences Theses & Dissertations

The inhibitory activity exhibited by Staphylococcus hominis strain αM toward Mycobacterium species was examined. These studies included determining the conditions that maximized inhibitory agent production, analyzing characteristics of the agent, determining the time of agent production, ascertaining plasmid possession and the role of plasmids in the production of this inhibitory agent, and ascertaining the antimicrobial activity of other strains of S. hominis. On solid and in liquid media, S. hominis strain αM exhibits a unique inhibitory activity toward Mycobacterium species that is not demonstrated by Staphylococcus epidermidis or other S. hominis strains. Maximum agent production and recovery was …

The Distribution And Occurrence Of Aerobic Heterotrophic Antimicrobic-Producing Bacteria Isolated From The Lower Chesapeake Bay, Linda Lea Gilmer

Biological Sciences Theses & Dissertations

Three different estuarine microenvironments in the lower Chesapeake Bay were investigated for the occurrence and geographical distribution of antimicrobic-producing bacteria. Samples were taken from the water column, fish skin, and algal surfaces. A total of 1472 bacterial isolates were assayed for antimicrobial activity against fungal, Gram-negative and Gram-positive bacterial test organisms. Of the total bacterial isolates assayed, 5. 2% were active antimicrobic producers. Algal surf aces were shown to have a higher incidence of antimicrobic-producing bacteria than the water column or fish skin. No antimicrobic activity was demonstrated by bacteria isolated from the flounder fish skin. The majority of the …

Biodegradation Of Crude Oil By Marine Higher Fungi, Brian J. Dyer

Biological Sciences Theses & Dissertations

Four experiments were performed to determine the ability of marine higher fungi to grow in and degrade crude oil. Eight species, previously determined to be hydrocarbonoclastic, were grown in artificial sea water medium (ASM) and southern Louisiana crude oil. The dry mycelial weights were measured and consumption of crude oil was measured gravimetrically. The two species with the best growth, Corollospora maritima and Zalerion maritimum, were grown in ASM containing crude oil spiked with three known hydrocarbons. To this was added glucose (0.15%) and incubated 49 days to test for possible cometabolism of hydrocarbons. Hydrocarbons remaining in the growth …

The Composition And Concentrations Of Cyanobacteria In The North Landing River, Virginia And Upper Currituck Sound, North Carolina, Sonja E. Midgette

Biological Sciences Theses & Dissertations

A 12 month study of cyanobacteria composition and concentrations in the North Landing River and upper Currituck Sound was conducted from March 1986 to February 1987. Epifluorescence microscopy and the fluorochrome proflavin were used to determine cell concentrations and vertical, station to station and seasonal distribution of these cells. Cyanobacterial assemblage patterns were coupled with pH, temperature, salinity and water transparency readings.

Cyanobacteria were found to be a persistent and prolific phytoplankton component of both the river and upper sound. For a comparison of vertical distribution for each station, an analysis of variance for. two groups of equal size was …

Interactions Between Aquatic Chromogenic Bacteria And Pathogenic Vibrio Spp., John Louis Harris

Biological Sciences Theses & Dissertations

Interactions between populations inhabiting an ecosys­tem are responsible, in large part, for determining which species coexist in that ecosystem. In this study, interac­tions between selected Vibrio species, V. alginolyticus and V. anguillarum, and marine heterotrophic, chromogenic bac­teria in aquatic microcosms were investigated. The ultimate goal of this project was to evaluate the feasibility of ex­ ploiting competitive interactions as a means to biologically control growth of the pathogenic marine bacteria, V. alginolyticus and V. anguillarum. In the majority of ex­periments (14/16), if chromogenic species were allowed to develop stable populations before a Vibrio spp. was intro­duced into a …

Short Term Temporal And Spatial Variability Of Phytoplankton In The Elizabeth River, Robert L. O'Reilly

Biological Sciences Theses & Dissertations

This study was designed to evaluate short-term temporal and spatial components of phytoplankton variability within a tidal estuarine system, in reference to natural changes in the local environment.

Multiple water samples were collected weekly from October to December 1984 at 4 stations in different branches, or sections, of the Elizabeth River. Collection of chlorophyll~ data was structured to fit an analysis of variance, while the phytoplankton species and their environmental relationships were analyzed using multivariate techniques.

Lower chlorophyll a concentrations from 0.75 to 2.87 ug/1 were characteristic of the Main Stem and Southern Branch, while higher values of 1.27 …

The Distribution Of Ceratia Over The Mid-Atlantic Bight, Paul V. Zimba

Biological Sciences Theses & Dissertations

The distribution and concentration of Ceratium species, between Cape Hatteras, North Carolina and Long Island, New York ls discussed in relation to specific physical factors and the development of a phytoplankton bloom. The progression of high Ceratium counts Is discussed for the Bight areas of New York, Delaware, and the Chesapeake Bay (April through June). The concentration of Ceratium species declined after June, with highest concentrations along the New York and Delaware coast-lines. Coastal regions (less than 12 km from shore) were associated with high concentrations of several species. Path and regression analysis were used to relate physical factors and …

Algal Dynamics In A Cypress Stand In The Seasonally Flooded Great Dismal Swamp, Joseph A. Atchue Iii

Biological Sciences Theses & Dissertations

The dynamics of epiphytic algae and phytoplankton were studied at a cypress stand in the Great Dismal Swamp, Virginia. Mean epiphytic algal biomass was 19.9 g m^-2 and mean planktonic biomass was 3.4 g m^-2.Nutrient concentrations in the epiphytic algae and the litter were determined. The algae had mean concentrations of 1.67% and 0.18%. They were found to immobilize as much as 0.5 g N m^-2 and 0.06 g P m^-2. This suggests that the algae are important as nutrient conservers. The phytoplankton were composed primarily of Bacillariophyceae. They exhibited a more or less …

Petroleum-Utilizing Bacteria: The Biological Line Defense Against Oil Pollution, Steven W. Sokolowski

Biological Sciences Theses & Dissertations

A silica gel-petroleum (SGP) medium was developed which is reliable, approximately the same cost as that of the corresponding agar-based petroleum medium, and can be made sufficiently firm to use in streaking or the spread-plate technique. Advantages of the medium include: the incorporation of all of the major ions of seawater in accordance with Dittmar's Law (the salinity of which can easily be varied from 0 to 35 parts per thousand); a wide workable pH range (5.5 to 11.6); negligable pH drift(~ 0.2 pH units after 166 days); the elimination of all but negligable amounts of syneresis, the ability to …

Isolation And Enumeration Of Enteric Viruses From Primary Wastewater Sludge, Michael Wayne Nath

Biological Sciences Theses & Dissertations

The presence of large numbers of enteric viruses in wastewaters has resulted in concern regarding their significance and consequences for humans. Assessments of relative significance or consequences may most accurately be made following precise measurements of the range of virus types and amounts in wastewaters and sludges and after epidemiological considerations. In this study, results are presented pertaining to enteric virus isolation, concentration, and enumeration from primary wastewater sludges.

As an integral part of a comparison of isolation procedures, several anionic surfactants were examined for extraction of enteric viruses from primary wastewater sludges. Plaquing efficiencies for poliovirus type 2 and …

The Development Of Techniques For The Enumeration Of Selected Pathogenic Bacteria In Lynnhaven Estuarine Sediments, Mark T. Frank

Biological Sciences Theses & Dissertations

Methodologies for the improved recovery of selected pathogenic bacteria from estuarine sediments were investigated. Laboratory and field studies were conducted to document the sensitivity of the techniques for isolating Salmonella species, Pseudomonas aeruginosa, and Vibrio parahaemolyticus. Vibrio parahaemolyticus-like organisms were enriched in a seawater yeast extract broth and isolated from Thiosulfate Citrate Bile Salts Sucrose plated media. Enrichment procedures with and without elevated temperatures and subsequent transfers to selective and differential plated media have been examined for the isolation of Salmonella species and P. aeruginosa. These pathogens were initially assayed for utilizing primary enrichments of asparagine …

A Potential Macroregulatory Mechanism For Growth Regulation In Neurospora Crassa, Martha Mooney

Biological Sciences Theses & Dissertations

Neurospora produces a phase specific, cationic mucopolysaccharide composed primarily of galactosamine (GAG-MP) which becomes part of the cell wall and is later secreted into the media. Its appearance coincides with the onset of the restricted phase of growth and causes efflux of small molecular weight metabolites when incubated with conidial cells. This activity may be a product of electrostatic interactions of the GAG-MP with the conidial plasma membrane. The activity is blocked by acetylation of the primary amines on the molecule, digestion by enzymes that hydrolyze carbohydrate linkages and the inclusion of NaCl (lM) in the GAG-MP/conidia reaction mixture. The …

Demonstration Of Unique Mycelial Components In Candida Albicans, David Jon Mancuso

Biological Sciences Theses & Dissertations

Mycelial (M) and blastopore (B) cell homogenates of Candida albicans strain BJ85 were compared to detect and recover unique M components. Qualitative differences in the protein and lipid content of Mand B homogenates were suggested by discontinuous polyacrylamide gel electrophoresis (DPAGE). In addition, a quantitative and possibly qualitative shift in the protein content during germ tube formation was implied by DPAGE. Unique M components were detected using both DPAGE and immunoelectrophoretic (IE) techniques. One unique M component by DPAGE, four by IE, and two by combined DPAGE and IE techniques were suggested. Of these three methods, only DPAGE and the …

Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoretic Studies Demonstrating Cytoplasmic Protein Components Unique To The Mycelial Phase And To The Yeast Phase Of Candida Albicans, Theresa Catherine Burgess

Biological Sciences Theses & Dissertations

Blastospore and mycelial cytoplasmic extracts from four strains of Candida albicans, varying in virulence, were compared by sodium dodecyl sulfate (SDS) polyacrylamide disc gel electrophoresis Cytoplasmic extracts were made by disrupting the cultures in a Braun homogenizer followed by ultracentrifugation. The supernatant fractions were then resolved on polyacrylamide gels containing SDS. Each of the preparations yielded a distinct pattern. There were mycelial specific and blastospore specific protein bands. There were more components resolved from the blastospore phase cytoplasmic extracts than from the mycelial phase cytoplasmic extracts. There were bands common to both phases. These results demonstrate protein components unique …

Seasonal Distribution Of Higher Marine And Aquatic Fungi In The Back Bay National Wildlife Refuge, Scott Schatz

Biological Sciences Theses & Dissertations

Abstract unavailable.

Comparison Of Interferon Produced In Vitro By Monkey Kidney Cells Demonstrating Interference Against Polio Ii, Coxsackie A-9, Influenza A2/Hong Kong/68, And Echo-9 Viruses, Archer Duncan Farmer Jr.

Biological Sciences Theses & Dissertations

Abstract unavailable

Phytoplankton Succession In The Lafayette River, Estuary, Norfolk, Virginia, Thomas W. Purcell Lll

Biological Sciences Theses & Dissertations

Abstract unavailable.