Digital Commons Network^™

A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane

Electronic Theses and Dissertations

Extraction of the lipids of Legionella pneumophila yields phases unlike those produced from other Gram-negative bacteria. A viscous interface forms between the aqueous (wash) and organic phases. More than half of the hydroxylated fatty acids were found distributed between the aqueous phase and the interfacial material, fractions in which such constituents have not been reported in other Gram-negative species. It was further observed that after the material from the aqueous/interfacial phase was dissolved in methanol or chloroform/methanol (2:1 (V/V)), the addition of acetone would create a white, flocculent precipitate. Analyses showed that the supernatant contained fatty acids that were nonhydroxylated …

Nitric Oxide Production: A Mechanism For Inhibition Of Chlamydia Trachomatis Replication, Bojun Chen

Electronic Theses and Dissertations

Chlamydia trachomatis (CT) replicates in macrophages, but is inhibited by IFN-$\gamma$ or LPS. IFN-$\gamma$ and/or LPS induced nitrite production in mouse peritoneal macrophages, macrophage cell lines (RAW264.7 and J774A.1) and McCoy cells. Kinetic studies indicated that peak production occurred 48 hours post-treatment. CT infection itself was insufficient to induce nitrite production, but resulted in enhancement of nitrite production in IFN-$\gamma$-treated cells. Treatment with IFN-$\gamma$ or LPS resulted in significant inhibition of CT replication in these cells. Strong correlation between nitrite production and inhibition of CT replication was observed in RAW264.7 and J774A.1 cells (correlation coefficients: $-$0.93 and $-$0.94, p $<$ 0.001). N$\sp{\rm g}$- monomethyl-L-arginine (L-NMMA) specifically inhibited nitrite production and partially reversed inhibition of CT replication in macrophage cell lines. NOS mRNA was measured in RAW264.7 cells by Northern blot and Dot blot hybridization. Strong correlation between NOS mRNA expression and inhibition of CT replication (correlation coefficient: $-$0.97, p $<$ 0.05) was observed. Anti-TNF-$\alpha$ antibody completely neutralized the biological activity of TNF-$\alpha$ secreted by LPS-treated RAW264.7 cells, yet the antibody neither reduced nitrite production nor restored CT replication. Combination of the antibody and L-NMMA significantly enhanced restoration of CT replication. In peritoneal macrophages, inhibition of CT replication induced by IFN-$\gamma$ was partially restored by L-NMMA or anti-TNF-$\alpha$ antibody. In McCoy cells, inhibition of CT replication induced by IFN-$\gamma$ and LPS was not significantly restored by L-NMMA. Great restoration of CT replication by 1 mM L-NMMA was observed in LPS-treated J774A.1 cells (31%), but not in IFN-$\gamma$-treated cells (5%). Our data indicate that (1) NO production is one of the mechanisms for inhibition of CT replication in IFN-$\gamma$-activated peritoneal macrophages and RAW264.7 cells; (2) NO plays a significant role in CT inhibition in LPS-treated macrophage cell lines, but not peritoneal macrophages; (3) TNF-$\alpha$ may be associated with inhibition, but the mechanism(s) may not involve NO production; (4) NO production may not be the mechanism for CT inhibition in McCoy cells treated with IFN-$\gamma$ and LPS.

The Role Of Flagellar Proteins In Adhesion Of Vibrio Parahaemolyticus, And Isolation Of The Corresponding Gene(S)., Ratchanee Hongprayoon

LSU Historical Dissertations and Theses

Polar flagellar core protein was purified from Vibrio parahaemolyticus by differential centrifugation and cesium chloride isopycnic centrifugation. Twelve hybridomas secreting monoclonal antibodies against flagellar core protein (MAb-flc) were obtained from fusions. By chance, one purified flagellar core preparation retained flagellar sheath and as a consequence, two hybridomas were detected which secreted anti-sheath antibodies (MAb-fls). MAb-flc and MAb-fls reacted specifically with their corresponding antigens as demonstrated by immunogold labelling. Coagglutination reagents prepared with MAb-flc and MAb-fls were tested against 34 strains of V. parahaemolyticus and 34 heterologous Vibrio species. The coagglutination results revealed that the flagellar core was species-specific while the …

Analysis Of Chromosomal Involvement In Yersinia Pestis Virulence Plasmid Expression, Teresa Sandelin Birrer

Doctoral Dissertations

Virulence plasmid expression in the Yersinia has been shown to vary depending upon which species harbors the virulence plasmid suggesting that chromosomal regulation may in some way be involved. In this study, fertility plasmid expression in Y. pestis was investigated as a means of evaluating mechanisms of virulence plasmid regulation in this bacterium. The F plasmid was found to be minimally expressed in Y. pestis transferring at a rate of 8.8 $\times$ 10$\sp{-5\%}.$ In addition, Y. pestis failed to express F pili as determined by infection with the male specific phage MS2. When F plasmids containing at least 2 E. …

Insertion Sequence Elements In Yersinia: Nucleotide Sequence Of Is100 Of Yersinia Pestis, Stephen Dale Torosian

Doctoral Dissertations

The World Health Organization classified (Williams, 1983) Y. pestis as Y. pseudotuberculosis subsp. pestis on the basis of DNA homology, yet the two organisms cause markedly different disease. Portnoy and Falkow (1981) reported IS100 to influence the virulence of Y. pestis. IS100 was shown to be found in Y. pestis but not Y. pseudotuberculosis.

IS100 from Y. pestis was sequenced and shown by sequence analysis to fulfill the requirements of being an IS element. pIS1C, an 821 bp fragment of IS100 was transferred to Y. pseudotuberculosis Trp-Ca-, resulting in the ability of the cells to ferment rhamnose and delayed production …

In Vitro Studies On The Interactions Between Toxoplasma Gondii And Its Host Cell., Sandra Karen Halonen

LSU Historical Dissertations and Theses

Toxoplasma gondii is an obligate intracellular protozoan parasite of the Phylum Apicomplexa. The parasite resides in the cytoplasm of its host cells in a membrane bound compartment called the parasitophorous vacuole. All growth and development of the parasite occur within this compartment. In this thesis, the interactions between the Vero cells, a fibroblast-like cell line, and the parasite which occur during the intracellular growth of the parasite were addressed. The impact of infection on the host cell intermediate filaments and microtubular cytoskeletal elements was examined by immunofluorescence microscopy. Host cell intermediate filaments were found to overcoat the parasite vacuole beginning …

Acetylation Of Seaweed Alginate By Pseudomonas Syringae., Jin Woo Lee

LSU Historical Dissertations and Theses

Acetylation of bacterial alginate by Pseudomonas syringae subsp. phaseolicola ATCC 19304 was independent of alginate biosynthesis. This allowed the development of a process for acetylating seaweed alginate using immobilized P. syringae ATCC 19304 cells. About 50% of the mannuronic acid residues of seaweed alginate were acetylated by carbon immobilized P. syringae cells in a fluidized bed, up-flow reactor system fed continuously with seaweed alginate and gluconic acid. O-Acetylation by this process was found to be specific for the C-2 and/or C-3 position(s) of mannuronate residues. Acetylated seaweed alginate showed altered properties including increased viscosity and changed affinities for some cations.

Characterization Of The Subunits Of The Mcrbc Restriction System In Escherichia Coli K12., Timothy Paul Beary

LSU Historical Dissertations and Theses

The McrBC (Modified Cytosine Restriction) restriction system has the ability to restrict DNA containing 5-hydroxymethylcytosine, N$\sp4$-methylcytosine, and 5-methylcytosine at specific sequences. The mcrB gene produces two gene products. The complete mcrB open reading frame produces a 53-kDa protein (McrB$\sb{\rm L}$) and a 35-kDa protein (McrB$\sb{\rm S}).$ The smaller McrB polypeptide is produced from an inframe, internal translational start in the mcrB gene. The mcrC gene produces a single 38-kDa protein. Evidence was presented that McrB$\sb{\rm S}$ regulates the activity of McrBC. When McrB$\sb{\rm S}$ was overproduced in a McrBC$\sp+$ background, there was dramatic loss of restriction. Underproduction of this protein …

Antimicrobial Properties Of Glycerol Monolaurate Either Alone Or Combined With Selected Organic Acids Against Listeria Monocytogenes., Deog-Hwan Oh

LSU Historical Dissertations and Theses

The objective of this study was to evaluate the antimicrobial properties of glycerol monolaurate (monolaurin) either alone or in combination with organic acids against Listeria monocytogenes in model broth or food. The minimal inhibitory concentration (MIC) of monolaurin was reduced by decreasing the pH value of the medium. The contribution of temperature to monolaurin effectiveness showed that lethal effects of monolaurin increased at higher temperatures and lower pH values, whereas, bacteriostatic effects on growth increased as temperature and pH decreased. The inhibitory effect of ethanol on the growth of L. monocytogenes was slight up to 2.5% ethanol, but was significant …

Characterization Of Invariant Membrane Proteins Of Trypanosoma (Duttonella) Vivax, Barbara Anne Burleigh

Digitized Theses

Monoclonal antibodies (mAbs), raised against whole, fixed, uncoated, culture forms of Trypanosoma (Duttonella) vivax, were used to identify two invariant membrane proteins of this protozoan parasite. Since non-variant membrane proteins of the cell surface, flagellar pocket and endocytic pathway are potential targets for the control of trypanosomiasis of livestock by immunization, the identification and characterization of invariant membrane proteins is a necessary preliminary step.;A 65 kDA invariant membrane glycoprotein (gp65), identified using mAb 4E1, was the main focus of this study. Immunolocalization studies using the monoclonal antibody (mAb 4E1) for immunofluorescence staining and immunoelectron microscopy, demonstrated that the 65 kDa …

Isolation And Characterization Of A Genetic Locus Involved In Growth And Pathogenicity On Tomato Plants By Pseudomonas Syringae Pv Tomato, Dennis Paul Jackson

Digitized Theses

Pseudomonas syringae pv. tomato is the causal agent of bacterial speck on tomato. An essential feature of this organism, in the pathogenic process, is its ability to enter the intercellular spaces of its host and use the available plant substrates for growth. Tomato leaves contain quantities of carbon energy in the form of carboxylates. A Tn5 mutant, DC3481, cannot utilize carboxylates as a source of carbon energy for growth (CA{dollar}\sp-{dollar}) and is nonpathogenic (Path{dollar}\sp-{dollar}) on tomato. The focus of this thesis was to utilize DC3481 to isolate and characterize P. syringae pv. tomato DNA sequences involved with growth and pathogenicity …

Host And Viral Determinants Influencing The Pathogenesis Of Coronavirus-Induced Neurological Disease In Rodents, John M. Pasick

Digitized Theses

Host and viral determinants influencing the outcome of coronavirus JHM infections of the CNS of rodents were investigated using intact animals and primary neural cell cultures. Two problems pertinent to the process of pathogenesis were addressed. The first was concerned with elucidating host factors responsible for controlling the age dependent nature for induction of the demyelinating form of disease in suckling rats. In the second, the basis of the relative resistance exhibited by inbred SJL/J mice to JHMV was examined in relation to both host and viral determinants.;Using primary, dissociated neural cultures from perinatal rats, several interesting aspects of host …