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Articles 7801 - 7830 of 8419

Full-Text Articles in Microbiology

Molecular Studies Of Kpnai And Kpnbi R-M Systems : In Klebsiella Pneumoniae M5a1 And Gm236, Nan Sook Lee Aug 1994

Molecular Studies Of Kpnai And Kpnbi R-M Systems : In Klebsiella Pneumoniae M5a1 And Gm236, Nan Sook Lee

Loma Linda University Electronic Theses, Dissertations & Projects

Two possible type I restriction-modification (R-M) systems, KpnAI and KpnBl, were recognized in Klebsiella pneumoniae strains M5al and GM236, respectively. In this project, four hsdRKpnAI clones (pNLA1 to pNLA4) were obtained by using an endonuclease expression-selection method. The hsdRKpnAI gene was identified on a 3.6 kb Sau3Al fragment. To map the gene, the hsdRKpnAI clone was hybridized to a membrane which contained pulsed-field gel electrophoresed fragments of the chromosome of the strain M5al. The hsdRKpnAI clone was hybridized to a 19 kb Xbal fragment and a 420 kb Blnl fragment, located …


High Rates Of Frameshift Mutations Within Homo-Oligomeric Runs During A Single Cycle Of Retroviral Replication, Dawn P. Wooley, H. M. Temin Jul 1994

High Rates Of Frameshift Mutations Within Homo-Oligomeric Runs During A Single Cycle Of Retroviral Replication, Dawn P. Wooley, H. M. Temin

Neuroscience, Cell Biology & Physiology Faculty Publications

Homo-oligomeric runs were inserted into a spleen necrosis virus-based retrovirus vector to determine the nature and rate of mutations within runs of 10 to 12 identical nucleotides during a single replication cycle. Clones of helper cells containing integrated copies of retroviral vectors were used to produce virus for infection of target (nonhelper) cells. Proviral sequences from target cell clones were compared with proviral sequences from helper cell clones to study mutations that occurred during a single cycle of replication. In addition to the internal region spanning the homo-oligomeric inserts, a naturally occurring run of 10 T's in the long terminal …


Nitrous Oxide Flux From Poultry-Manured Erosion Plots And Grass Filters After Simulated Rain, Mark S. Coyne, R. A. Gilfillen, Robert L. Blevins Jul 1994

Nitrous Oxide Flux From Poultry-Manured Erosion Plots And Grass Filters After Simulated Rain, Mark S. Coyne, R. A. Gilfillen, Robert L. Blevins

Plant and Soil Sciences Faculty Publications

Adding carbon-rich materials to fields, like manure, may enhance denitrification. Grass filters, which are used to trap surface runoff from these fields, may also provide a carbon-rich environment that favors water infiltration and denitrification. Nitrous oxide (N2O) may be evolved these settings. It is a radiatively important trace gas and intermediate in the denitrification pathway and several other microbial processes. We measured N2O flux, after simulated rain, using a soil cover technique in poultry-manured plots and grass filters receiving their runoff. Intact soil cores were used to relate the N2O flux to the denitrification …


Molecular Analysis Of The Rfb Gene Cluster Of A Group D2 Salmonella Enterica Strain: Evidence For Its Origin From An Insertion Sequence-Mediated Recombination Event Between Group E And Dl Strains, Shi-Hua Xiang, Matthew Hobbs, Peter R. Reeves Jul 1994

Molecular Analysis Of The Rfb Gene Cluster Of A Group D2 Salmonella Enterica Strain: Evidence For Its Origin From An Insertion Sequence-Mediated Recombination Event Between Group E And Dl Strains, Shi-Hua Xiang, Matthew Hobbs, Peter R. Reeves

Nebraska Center for Virology: Faculty Publications

The Salmonella enterica O antigen is a highly variable surface polysaccharide composed of a repeated oligosaccharide (the O unit). The O unit produced by serogroup D2 has structural features in common with those of groups Dl and El, and hybridization studies had previously suggested that the D2 rfb gene cluster responsible for O-unit biosynthesis is indeed a hybrid of the two. In this study, the rfb gene cluster was cloned from a group D2 strain of S. enterica sv. Strasbourg. Mapping, hybridization, and DNA sequencing showed that the organization of the D2 rfb genes is similar to that of group …


Adoptive Transfer Of Polyclonal And Cloned Cytolytic T Lymphocytes (Ctl) Specific For Mouse Aids-Associated Tumors Is Effective In Preserving Ctl Responses: A Measure Of Protection Against Lp-Bm5 Retrovirus-Induced Immunodeficiency., William R. Green, Kathy A. Green, Karen M. Crassi Jul 1994

Adoptive Transfer Of Polyclonal And Cloned Cytolytic T Lymphocytes (Ctl) Specific For Mouse Aids-Associated Tumors Is Effective In Preserving Ctl Responses: A Measure Of Protection Against Lp-Bm5 Retrovirus-Induced Immunodeficiency., William R. Green, Kathy A. Green, Karen M. Crassi

Dartmouth Scholarship

Cytolytic T lymphocytes (CTL) can be raised against C57BL/6 B-cell lymphomas from mice with LP-BM5 murine leukemia virus-induced AIDS (MAIDS). Adoptive transfer of polyclonal anti-MAIDS tumor CTL or two CTL clones specific for the B6-1710 MAIDS lymphoma caused preservation of major histocompatibility complex-restricted and allogeneic CTL responses, which may be interpreted as indices of protection from LP-BM5 murine leukemia virus-induced immunodeficiency.


Differential Resource Consumption Obviates A Potential Flight–Fecundity Trade-Off In The Sand Cricket (Gryllus Firmus), S. Mole, Anthony J. Zera Jun 1994

Differential Resource Consumption Obviates A Potential Flight–Fecundity Trade-Off In The Sand Cricket (Gryllus Firmus), S. Mole, Anthony J. Zera

Anthony Zera Publications

1. The physiological basis of life-history trade-offs is poorly understood. A useful system in which the underlying physiological mechanisms can be studied is wing polymorphism in insects.
2. The sand cricket, Gryllus firmus (Orthoptera, Gryllidae), exists in natural populations as either a fully-winged (LW), flight-capable morph or as a short-winged (SW) morph that cannot fly.
3. We characterized the morphs with respect to physiological features that influence a potential trade-off between flight capability and fecundity. We measured nutritional indices, flight muscle development and ovarian development in the LW and SW morphs.
4. In adults, ovarian growth occurred after the completion …


Phylogenetic Associations Of Human And Simian T-Cell Leukemia/Lymphotropic Virus Type I Strains: Evidence For Interspecies Transmission, Igor J. Koralnik, Enzo Boeri, W. Carl Saxinger, Anita Lo Monico, Jake Fullen, Antoine Gessain, Hong-Guang Guo, Robert C. Gallo, Phillip Markham, Vaniambadi Kalyanaraman, Vanessa Hirsch, Jonathan Allan, Krishna Murthy, Patricia Alford, Jill Pecon-Slattery, Stephen J. O'Brien, Genoveffa Ranchini Apr 1994

Phylogenetic Associations Of Human And Simian T-Cell Leukemia/Lymphotropic Virus Type I Strains: Evidence For Interspecies Transmission, Igor J. Koralnik, Enzo Boeri, W. Carl Saxinger, Anita Lo Monico, Jake Fullen, Antoine Gessain, Hong-Guang Guo, Robert C. Gallo, Phillip Markham, Vaniambadi Kalyanaraman, Vanessa Hirsch, Jonathan Allan, Krishna Murthy, Patricia Alford, Jill Pecon-Slattery, Stephen J. O'Brien, Genoveffa Ranchini

Biology Faculty Articles

Homologous env sequences from 17 human T-leukemia/lymphotropic virus type I (HTLV-I) strains from throughout the world and from 25 simian T-leukemia/lymphotropic virus type I (STLV-I) strains from 12 simian species in Asia and Africa were analyzed in a phylogenetic context as an approach to resolving the natural history of these related retroviruses. STLV-I exhibited greater overall sequence variation between strains (1 to 18% compared with 0 to 9% for HTLV-I), supporting the simian origin of the modern viruses in all species. Three HTLV-I phylogenetic clusters or clades (cosmopolitan, Zaire, and Melanesia) were resolved with phenetic, parsimony, and likelihood analytical procedures. …


Evidence For Dna Methylation-Sensitive Transactivator Mediated Regulation Of The Expression Of An Epstein-Barr Virus Neutralizing Antigen, Sridhar Chalasani Apr 1994

Evidence For Dna Methylation-Sensitive Transactivator Mediated Regulation Of The Expression Of An Epstein-Barr Virus Neutralizing Antigen, Sridhar Chalasani

Masters Theses

DNA methylation has a profound effect on the expression of a number of eukaryotic genes. This study demonstrates that an Epstein-Barr virus (EBV) positive Burkitt's lymphoma cell line, Raji, contains the gene encoding gp350/220 but is not expressed. Frog virus 3 (FV3), an iridovirus, has the ability to overcome the inhibitory effect of DNA methylation. Fusion of FV3-infected cells with Raji cells resulted in expression of gp350/220, suggesting that gp350/220 is regulated by DNA methylation. Further evidence for this hypothesis was obtained by transfecting B95.8 cells with HpaII/HhaI methylated plasmid pLATE-CAT, containing the gp350/220 promoter. Southern blot analyses and a …


Translational Regulation Of The C-Jun Proto-Oncogene, Anil Sehgal Apr 1994

Translational Regulation Of The C-Jun Proto-Oncogene, Anil Sehgal

Theses and Dissertations in Biomedical Sciences

The v-jun oncogene was originally isolated from the ASV17 virus in 1987. Ever since its isolation, extensive work has been done to understand the role of the v-jun oncogene in cell transformation. The c-Jun protein is a transcription factor which binds to the DNA target TGACTCA. The c-Jun protein binds to DNA in the form of dimers. It can form homodimers with itself and heterodimers with Jun family (JunB and JunD), Fos family (FosB, Fra1 and Fra2), or with CREB family members through the leucine zipper motif. Because the c-jun proto-oncogene plays an important role in cell transformation, extensive work …


Amoebic Appendicitis--A Rare Entity, Raheem Ahmed, Hizbullah Shaikh, Muhammad Siddiqui, M Ahmed Apr 1994

Amoebic Appendicitis--A Rare Entity, Raheem Ahmed, Hizbullah Shaikh, Muhammad Siddiqui, M Ahmed

Department of Pathology and Laboratory Medicine

Appendectomy is the most common surgical procedure performed in routine general surgical practice. However, not all the appendices removed, are submitted for histopathological examination in this part of the world. We reviewed 1400 appendices received by our department from within our hospital and from outside the hospital. Of these 13 cases were reported as amoebic appendicitis. These patients did not have any different clinical presentation from the patients who were reported as acute appendicitis without amoebae. Microscopically these appendices had minimal neutrophil polymorph infiltration accompanied by tissue necrosis and amoebic trophozoites within the appendiceal wall. After histological diagnosis, different tests …


Phylogenetic Analysis Of Segment 10 From African Horsesickness Virus And Cognate Genes From Other Orbiviruses, Rafael O. De Sá, Marla Zellner, Marvin J. Grubman Mar 1994

Phylogenetic Analysis Of Segment 10 From African Horsesickness Virus And Cognate Genes From Other Orbiviruses, Rafael O. De Sá, Marla Zellner, Marvin J. Grubman

Biology Faculty Publications

Utilizing the reverse transcriptase-polymerase chain reaction (RT-PCR) procedure, we have synthesized full-length copies of segment 10 from African horsesickness virus (AHSV) serotypes 1,4 and 8. The genes were cloned, sequenced and compared with the sequence of the cognate gene from AHSV serotypes 3 and 9. Sequences were analyzed to assess evolutionary relationships among serotypes using cladistics. Based on this analysis the data support a close relationship between serotypes 4 and 9 and between serotypes 1 and 8 and a closer relationship of serotype 3 to the 4 and 9 group.


Estimation Of Diversity And Community Structure Through Restriction-Fragment-Length-Polymorphism Distribution Analysis Of Bacterial 16s Ribosomal-Rna Genes From A Microbial Mat At An Active, Hydrothermal Vent System, Loihi Seamount, Hawaii, Craig L. Moyer, Fred C. Dobbs, David M. Karl Mar 1994

Estimation Of Diversity And Community Structure Through Restriction-Fragment-Length-Polymorphism Distribution Analysis Of Bacterial 16s Ribosomal-Rna Genes From A Microbial Mat At An Active, Hydrothermal Vent System, Loihi Seamount, Hawaii, Craig L. Moyer, Fred C. Dobbs, David M. Karl

OES Faculty Publications

PCR was used to amplify (eu)bacterial small-subunit (16S) rRNA genes from total-community genomic DNA. The source of total-community genomic DNA used for this culture-independent analysis was the microbial mats from a deep-sea, hydrothermal vent system, Pele's Vents, located at Loihi Seamount, Hawaii. Oligonucleotides complementary to conserved regions in the 16S rRNA-encoding DNA (rDNA) of bacteria were used to direct the synthesis of PCR products, which were then subcloned by blunt-end ligation into phagemid vector pBluescript II. Restriction fragment length polymorphism patterns, created by using tandem tetrameric restriction endonucleases, revealed the presence of 12 groups of 16S rRNA genes representing discrete …


Effect Of Iron Availability On Expression Of The Bradyrhizobium Japonicum Hema Gene., Karen M. Page, Erin Connolly, Mary Lou Guerinot Mar 1994

Effect Of Iron Availability On Expression Of The Bradyrhizobium Japonicum Hema Gene., Karen M. Page, Erin Connolly, Mary Lou Guerinot

Dartmouth Scholarship

Bradyrhizobium japonicum produces delta-aminolevulinic acid, the universal precursor of tetrapyrroles, in a reaction catalyzed by the product of the hemA gene. Expression of the B. japonicum hemA gene is affected by iron availability. Activity of a hemA-lacZ fusion is increased approximately threefold by iron, and RNA analysis indicates that iron regulation is at the level of mRNA accumulation. To our knowledge, this is the first example of an iron-regulated heme biosynthetic gene in prokaryotes.


The Amino-Terminal Functions Of The Simian Virus 40 Large T Antigen Are Required To Overcome Wild-Type P53-Mediated Growth Arrest Of Cells., Robin S. Quartin, Charles N. Cole, James M. Pipas, Arnold J. Levine Mar 1994

The Amino-Terminal Functions Of The Simian Virus 40 Large T Antigen Are Required To Overcome Wild-Type P53-Mediated Growth Arrest Of Cells., Robin S. Quartin, Charles N. Cole, James M. Pipas, Arnold J. Levine

Dartmouth Scholarship

High levels of the p53 tumor suppressor protein can block progression through the cell cycle. A model system for the study of the mechanism of action of wild-type p53 is a cell line (T64-7B) derived from rat embryo fibroblasts transformed by activated ras and a temperature-sensitive murine p53 gene. At 37 to 39 degrees C, the murine p53 protein is in a mutant conformation and the cells actively divide, whereas at 32 degrees C, the protein has a wild-type conformation and the cells arrest in the G1 phase of the cell cycle. Wild-type simian virus 40 large T antigen and …


Use Of Pyocin To Select A Haemophilus Ducreyi Variant Defective In Lipooligosaccharide Biosynthesis, A A. Campagnari, R Karalus, M A. Apicella, William Melaugh, A J. Lesse, B W. Gibson Jan 1994

Use Of Pyocin To Select A Haemophilus Ducreyi Variant Defective In Lipooligosaccharide Biosynthesis, A A. Campagnari, R Karalus, M A. Apicella, William Melaugh, A J. Lesse, B W. Gibson

Chemistry Faculty Publications

Haemophilus ducreyi, a cause of genital ulcer disease in developing countries, appears to facilitate the heterosexual transmission of the human immunodeficiency virus in Africa. Despite an increase in studies of this gram-negative human pathogen, little is known about the pathogenesis of chancroid. Our studies have shown that the lipooligosaccharides (LOS) of H. ducreyi may play an important role in ulcer formation. Monoclonal antibody and mass spectrometric analyses identified a terminal trisaccharide present on H. ducreyi LOS that is immunochemically similar to human paragloboside. This epitope is present on the LOS of Neisseria gonorrhoeae, and it may be the site of …


Cyanonews (Vol. 10, No. 2, July 1994), Jeff Elhai Jan 1994

Cyanonews (Vol. 10, No. 2, July 1994), Jeff Elhai

CyanoNews

CyanoNews was a newsletter that served the cyanobacteriological community from 1985 to 2003, with content provided by readers (sort of a blog before there were blogs). The newsletter reported new findings from the lab, summaries of recent meetings (often provided by graduate students and post-docs entering the field), positions sought or available, life transitions, a compendium of recent cyanobacteria-related articles, and other items of interest to those who study cyanobacteria.


Cyanonews (Vol. 10, No. 1, February 1994), Jeff Elhai Jan 1994

Cyanonews (Vol. 10, No. 1, February 1994), Jeff Elhai

CyanoNews

CyanoNews was a newsletter that served the cyanobacteriological community from 1985 to 2003, with content provided by readers (sort of a blog before there were blogs). The newsletter reported new findings from the lab, summaries of recent meetings (often provided by graduate students and post-docs entering the field), positions sought or available, life transitions, a compendium of recent cyanobacteria-related articles, and other items of interest to those who study cyanobacteria.


60 Hz Magnetic Field Exposure Inhibits Protein Kinase C Dependent Induction Of Neuropeptide Y Mrna In Pc-12 Cells, William James Thomas Jan 1994

60 Hz Magnetic Field Exposure Inhibits Protein Kinase C Dependent Induction Of Neuropeptide Y Mrna In Pc-12 Cells, William James Thomas

Theses Digitization Project

The effects of MF exposure on the chemically induced production of NPY mRNA in the rat pheochromocytoma, PC-12 cell line.


Virus Diseases Of Subterranean Clover Pastures And Their Management, David Ferris, Roger Jones Jan 1994

Virus Diseases Of Subterranean Clover Pastures And Their Management, David Ferris, Roger Jones

Journal of the Department of Agriculture, Western Australia, Series 4

In Western Australia and southern Australia generally, subterranean clover mottle (SCMV) and bean yellow mosaic (BYMV) are the most damaging virus diseases of subterranean clover pastures.

Although infected plants cannot be cured of virus infection, pastures can be managed to reduce both virus spread and persistence from year to year. Management options depend on which virus is present and include reseeding with resistant varieties; changing the pasture composition so that non-host species predominate; altering grazing practices to limit spread; and application of pesticide sprays to kill aphids.


Miscellaneous Publication No 33/93 - Virulent Footrot A Farmer's Guide To Eradication, Department Of Agriculture, Western Australia Jan 1994

Miscellaneous Publication No 33/93 - Virulent Footrot A Farmer's Guide To Eradication, Department Of Agriculture, Western Australia

Animal production and livestock published reports

The first thing to understand about virulent footrot is that it can occur on any farm in the medium to high rainfall zone. Persons who regularly buy and sell sheep have a greater risk, but even closed breeding flock properties are at risk from stray sheep.

People often associate footrot with properties managed by inefficient farmers. This is a false belief. Many good farmers have found the disease in their sheep, including high profile studs.

Footrot can strike anywhere and often without warning.

The important thing to remember is that once it is found, getting to know and understand the …


Characterization Of Fibroblasts With A Unique Defect In Processing Antigens With Disulfide Bonds, Brian J. Merkel Jan 1994

Characterization Of Fibroblasts With A Unique Defect In Processing Antigens With Disulfide Bonds, Brian J. Merkel

Theses and Dissertations

A Chinese hamster ovary (CHO) fibroblast, transfected with murine major histocompatibility complex (MHC) class II genes, inefficiently simulated CD4+ Th cells specific for ovalbumin (OVA), hen egg lysozyme (HEL), and pork insulin which contains disulfide bonds. However, the fibroblasts elicited a T cell response to λ-repressor, which lacks disulfide bonds, and efficiently presented synthetic peptides. A somatic cell hybrid WALC, generated by fusing the hamster fibroblast with a murine L cell fibroblast, very efficiently processed OVA and HEL, suggesting that impaired processing was genetically complemented, suggesting that the processing defect is a recessive trait. Three distinct processing phenotypes were observed …


A Biosystematic Study Of Three Plant Pathogenic Fungi, Richard James Langham Jan 1994

A Biosystematic Study Of Three Plant Pathogenic Fungi, Richard James Langham

Masters Theses

Isolates of Chalara australis, Eucalypt Ceratocystis, and Ceratocystis virescens were grown on Potato Dextrose Agar, Malt Extract Agar, and Czapek Agar and examined as part of a biosystematic study on these fungi. Basic micromorphological and macromorphological data on the cultures were recorded and the taxa were found to be morphologically similar. Tissue isolates and single spore isolates were crossed within these taxa and an interspecific cross performed. Chalara australis was found to be either asexual or have only one mating type present in the cultures studied. Eucalypt Ceratocystis was found to have a mating system characteristic of bipolar …


Relative Sensitivities Of Diatoms To Selected Heavy Metals, Jennifer E. Carlson Jan 1994

Relative Sensitivities Of Diatoms To Selected Heavy Metals, Jennifer E. Carlson

Masters Theses

Baseline data, including diatom community structure, metal concentrations of water, sediments and periphyton of the Embarras River were determined previously (Vaultonburg, 1991). Data on diatom community structure in conjunction with efforts to identify relative sensitivity of diatoms may be useful in establishing an effective method for biomonitoring metal pollution in the Embarras River and other aquatic systems. The main objectives of this project were: i) develop a bioassay method; ii) evaluate relative toxicities of several metals towards diatoms; and, iii) evaluate relative sensitivities of diatoms toward dissolved metals.

Unialgal cultures of Cyclotella meneghiniana, Navicula vaucheriae, and Nitzschia palea were isolated …


Frequency Of Mug Negative Escherichia Coli In Kentucky Groundwater Samples, Mark S. Coyne, J. C. Shuler Jan 1994

Frequency Of Mug Negative Escherichia Coli In Kentucky Groundwater Samples, Mark S. Coyne, J. C. Shuler

Plant and Soil Sciences Faculty Publications

MUG negative Escherichia coli are a small fraction (2.5%) of the total E. coli in Kentucky groundwater samples. It is unlikely that they alone will cause a significant potential to underestimate fecal contamination using MUG as the primary criterion for that assessment. An unresolved question is how effectively MUG-based, defined-substrate tests address false negative water samples containing MUG positive E. coli.


Vh And D Gene Usage In B-Lineage Cells From Young Rabbits, Martha L. Friedman Jan 1994

Vh And D Gene Usage In B-Lineage Cells From Young Rabbits, Martha L. Friedman

Master's Theses

No abstract provided.


Development And Application Of A Thermistor Current Meter, Carl M. Way, Albert J. Burky, Christine Miller-Way Jan 1994

Development And Application Of A Thermistor Current Meter, Carl M. Way, Albert J. Burky, Christine Miller-Way

Biology Faculty Publications

This report provides details for the construction of a hot-bead thermistor current meter which is capable of measuring water velocities on a millimeter spatial scale and for the construction of a compact and accurate calibration system. Hot-bead thermistor current meters can be built with response times of 200 ms capable of measuring velocities between 0.1 and 80 cm s-1. The construction of a sturdy probe for application in lotic systems such as high gradient Hawaiian streams was achieved by the use of heavy-duty acrylic tubing, small stainless steel gas-chromatography tubing, and flexible Tygon spaghetti tubing. An acrylic handle anchors the …


Identification, Enrichment, And Cytokine Production Of Murine Bone Marrow Stromal Cells, Phillip E. Funk Jan 1994

Identification, Enrichment, And Cytokine Production Of Murine Bone Marrow Stromal Cells, Phillip E. Funk

Dissertations

No abstract provided.


Nonhomologous Rna Recombination In Tombusviruses: Generation And Evolution Of Defective Interfering Rnas By Stepwise Deletions, K. Andrew White, Thomas Jack Morris Jan 1994

Nonhomologous Rna Recombination In Tombusviruses: Generation And Evolution Of Defective Interfering Rnas By Stepwise Deletions, K. Andrew White, Thomas Jack Morris

Nebraska Center for Virology: Faculty Publications

We used a protoplast system to study the mechanisms involved in the generation and evolution of defective interfering (DI) RNAs of tomato bushy stunt tombusvirus (TBSV). Synthetic transcripts corresponding to different naturally occurring TBSV DI RNAs, or to various artificially constructed TBSV defective RNAs, were analyzed. The relative levels of competitiveness of different DI RNAs were determined by coinoculating their corresponding transcripts into protoplasts along with helper genomic RNA transcripts and monitoring the level of DI RNA accumulation. Further studies were performed to assess the contribution of naked DI RNA stability and DI RNA encapsidation efficiency to the observed levels …


A Characterization Of Extractable, Hydroxylated Fatty Acid Bearing Components In Legionella Pneumophila, Jonathan R. Lane Dec 1993

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 Dec 1993

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.