Microbiology Commons^™

A Bacterial Symbiont Is Converted From An Inedible Producer Of Beneficial Molecules Into Food By A Single Mutation In The Gaca Gene, Pierre Stallforth, Debra A. Brock, Alexandra M. Cantley, Xiangjun Tian, David C. Queller, Joan E. Strassmann, Jon Clardy

Biology Faculty Research

Stable multipartite mutualistic associations require that all partners benefit. We show that a single mutational step is sufficient to turn a symbiotic bacterium from an inedible but host-beneficial secondary metabolite producer into a host food source. The bacteria's host is a "farmer" clone of the social amoeba Dictyostelium discoideum that carries and disperses bacteria during its spore stage. Associated with the farmer are two strains of Pseudomonas fluorescens, only one of which serves as a food source. The other strain produces diffusible small molecules: pyrrolnitrin, a known antifungal agent, and a chromene that potently enhances the farmer's spore production and …

Development Of A Recombinant Lactobacillus Salivarius For Prophylactic Applications Against Mycobacterium Avium Subspecies Paratuberculosis And Johne’S Disease, Christopher Johnston

Theses

Current whole-cell vaccines against Mycobacterium avium subsp. paratuberculosis, the etiological agent of Johne’s disease, are unable to provide complete protection against infection. Moreover, such whole-cell formulations interfere with diagnostic tests for bovine tuberculosis (Mycobacterium bovis). The development of subunit vaccines, those which are preferentially based on one, or a select few, immunodominant protective antigens is considered as the realistic next step in overcoming these issues. The (MAP) K-10 genome is a single circular chromosome of 4,829,781 base pairs and encodes 4,350 predicted ORFs. In order to identify MAP specific proteins for subsequent incorporation within a mucosal based vaccine development, a …

Genetic Diversity Of Plasmodium Vivax Clinical Isolates From Southern Pakistan Using Pvcsp And Pvmsp1 Genetic Markers, Afsheen Raza, Najia K. Ghanchi, Ali M. Thaver, Sana Jafri, Mohammad A. Beg

Department of Pathology and Laboratory Medicine

Background:
Plasmodium vivax is the prevalent malarial species accounting for 70% of malaria burden in Pakistan; however, there is no baseline data on the circulating genotypes. Studies have shown that polymorphic loci of gene encoding antigens pvcsp and pvmsp1 can be used reliably for conducting molecular epidemiological studies. Therefore, this study aimed to bridge the existing knowledge gap on population structure on P. vivax from Pakistan using these two polymorphic genes.
Methods:
During the period January 2008 to May 2009, a total of 250 blood samples were collected from patients tested slide positive for P. vivax, at the Aga Khan …

Presenting Fake Figures: A Tool To Teach Effective Scientific Figure Design, Verónica A. Segarra, Stephanie Pulford, Susan Walsh

Faculty Publications

No abstract provided.

Bacterial Assemblages And Microbial Enzyme Activity In The Major Tributaries Of The Lower Mississippi River, Justin Millar

Electronic Theses and Dissertations

Spatial variation in the structure and function of bacterial communities is far more complex than previously believed. High throughput sequencing techniques have begun to elucidate the dynamic worldwide patterns of bacterial biogeography; however, there are still many ecosystems for which there is little to no representative data. Currently there are no high throughput-based analyses of bacterial assemblages in large rivers. Rivers form important connections between terrestrial land use and marine biogeochemistry and act as conduits for organisms and allochthonous nutrients. Bacteria dominate carbon cycling and nutrient processing in rivers, and therefore can influence regional and global elemental cycles. This study …

The Characterization Of The Interplay Between Sumoylation And Influenza A Virus, Andres Santos

Open Access Theses & Dissertations

Influenza A virus is a negative sense single stranded RNA virus responsible for multiple devastating pandemics in the past. This virus is capable of entering multiple eukaryotic hosts, sequestering, and using their cellular machinery for its own replicative purposes. This plethora of molecular events is all orchestrated through a shockingly limited repertoire of only 11 viral proteins. All of which are all strictly dependent on cellular processes such as post-transcriptional regulation, protein translation, post-translational modifications, etc. This study is focused on the characterization of the interplay between Influenza A virus and the cellular SUMOylation system. The first part of this …

Metagenome Sequence Analysis Of Filamentous Microbial Communities Obtained From Geochemically Distinct Geothermal Channels Reveals Specialization Of Three Aquificales Lineages, Cristina Takacs-Vesbach, William P. Inskeep, Zackary J. Jay, Markus J. Herrgard, Douglas B. Rusch, Susannah G. Tringe, Mark A. Kozubal, Natsuko Hamamura, Richard E. Macur, Bruce W. Fouke, Anna-Louise Reysenbach, Timothy R. Mcdermott, Ryan Dem. Jennings, Nicolas W. Hengartner, Gary Xie

Biology Faculty Publications and Presentations

The Aquificales are thermophilic microorganisms that inhabit hydrothermal systems world- wide and are considered one of the earliest lineages of the domain Bacteria. We analyzed metagenome sequence obtained from six thermal “filamentous streamer” communities (∼40 Mbp per site), which targeted three different groups of Aquificales found in Yellow- stone National Park (YNP). Unassembled metagenome sequence and PCR-amplified 16S rRNA gene libraries revealed that acidic, sulfidic sites were dominated by Hydrogenobac- ulum (Aquificaceae) populations, whereas the circum-neutral pH (6.5–7.8) sites containing dissolved sulfide were dominated by Sulfurihydrogenibium spp. (Hydrogenothermaceae). Thermocrinis (Aquificaceae) populations were found primarily in the circum-neutral sites with undetectable …

Exploitation Of The Bacteriophage-Derived Peptidase Chapk, Pierre-Mehdi Hadbi

Theses

This project investigated an anti-staphylococcal bacteriophage-derived peptidoglycan hydrolase enzyme, namely a cysteine-histidine amydohydrolase/peptidase (CHAP_k). The study focused firstly on optimizing the production of recombinant CHAP_k, which was previously cloned in an E. coli expression system, and sets out the resulting optimal Standard Operating Procedures (SOPs) for production, purification and determination of concentration and activity of the resulting protein stock. A typical yield resulting from the investigation was 300pg of CHAP_k from one litre of E.coli culture. The activity of the purified enzyme was typically in the region of 190U nmol ’. Secondly, the project investigated …

The Isolation And Characterisation Of Acientobacter Baumannii Bacteriophage, Mohamed Farag M. Elbreki

Theses

Acinetobacter baumannii is a pathogen, which has an increasing prevalence of multidrug resistance. It exists widely in natural environments, and frequently in health-care settings where it has proven difficult to eradicate using antibiotic therapy. A possible alternative to conventional antibiotics is the use of bacteriophages (phages) as antibacterials. In this project, extensive screening of environmental samples such as soils, sewage and waters was undertaken to identify suitable phages. Three phages were successfully isolated from municipal waste in the Cork area. These were subsequently characterized in detail and examined by electron microscopy, which showed that they were all of the Myoviridae …

Hypoxia Inducible Factor 1 Alpha (Hif-1a): A Major Regulator Of Placental Development, Renee E. Albers

Browse all Theses and Dissertations

Hypoxia-inducible factor-1 alpha (HIF-1a) is a critical component of the cellular oxygen-sensing machinery and is essential for placental formation and embryonic survival. In this study, we promoted prolonged expression of HIF-1a, by using a form that is insensitive to oxygen, denoted as CA-HIF-1a. In order to have continual placental specific expression of the CA-HIF-1a, lentiviral infection was performed on embryos at the blastocyst stage of development and transferred into pseudo-pregnant mothers. Placental analysis was performed via in situ hybridization on embryonic day 14.5 (E14.5) to determine the effects of CA-HIF-1a prolonged expression. Data indicate that prolonged activity of CA-HIF-1a restricted …

Antilisterial Characteristics Of Volatile Essential Oils, Leeann L. Slaughter

Theses and Dissertations--Animal and Food Sciences

This study explored the in vitro and in situ antilisterial inhibitory activity of 16 essential oils during indirect exposure: Spanish Basil oil (Ocimum basilicum), Bay oil (Pimenta racemosa), Italian Bergamot oil (Citrus bergamia), Roman Chamomile oil (Anthemis nobilis), Sir Lanka Cinnamon oil (Cinnamomum zeylanicum), Citral, Clove Bud oil (Syzygium aromaticum), Cumin Seed oil (cuminum cyminum), Eucalyptus oil (Eucalyptus globulus), Eugenol, Geranium extract (Pelargonium graveolens), Marjoram oil (Origanum majorana), Neroli extract (Citrus aurantium), Peppermint oil (Mentha piperita L.), …

Combined Effects Of Co2 And Light On Large And Small Isolates Of The Unicellular N2-Fixing Cyanobacterium Crocosphaera Watsonii From The Western Tropical Atlantic Ocean, Nathan S. Garcia, Fei-Xue Fu, Cynthia L. Breene, Elizabeth K. Yu, Peter W. Bernhardt, Margaret R. Mulholland, David A. Hutchins

OES Faculty Publications

We examined the combined effects of light and pCO₂ on growth, CO₂-fixation and N₂-fixation rates by strains of the unicellular marine N₂-fixing cyanobacterium Crocosphaera watsonii with small (WH0401) and large (WH0402) cells that were isolated from the western tropical Atlantic Ocean. In low-pCO₂-acclimated cultures (190ppm) of WH0401, growth, CO₂-fixation and N₂-fixation rates were significantly lower than those in cultures acclimated to higher (present-day approximate to 385ppm, or future approximate to 750ppm) pCO² treatments. Growth rates were not significantly different, however, in low-pCO₂-acclimated cultures of …

The Relative Contribution Of Methanotrophs To Microbial Communities And Carbon Cycling In Soil Overlying A Coal-Bed Methane Seep, Christopher T. Mills, Gregpry F. Slater, Robert F. Dias, Stephanie A. Carr, Christopher M. Reddy, Raleigh Schmidt, Kevin W. Mandernack

Chemistry & Biochemistry Faculty Publications

Seepage of coal-bed methane (CBM) through soils is a potential source of atmospheric CH₄ and also a likely source of ancient (i.e. ¹⁴C-dead) carbon to soil microbial communities. Natural abundance ¹³C and ¹⁴C compositions of bacterial membrane phospholipid fatty acids (PLFAs) and soil gas CO₂ and CH₄ were used to assess the incorporation of CBM-derived carbon into methanotrophs and other members of the soil microbial community. Concentrations of type I and type II methanotroph PLFA biomarkers (16:1ω8c and 18:1ω8c, respectively) were elevated in CBM-impacted soils compared with a control site. Comparison …

The Use Of Metagenomic Approaches To Analyze Changes In Microbial Communities, Girish Neelakanta, Hameeda Sultana

Biological Sciences Faculty Publications

Microbes are the most abundant biological entities found in the biosphere. Identification and measurement of microorganisms (including viruses, bacteria, archaea, fungi, and protists) in the biosphere cannot be readily achieved due to limitations in culturing methods. A non-culture based approach, called “metagenomics”, was developed that enabled researchers to comprehensively analyse microbial communities in different ecosystems. In this study, we highlight recent advances in the field of metagenomics for analyzing microbial communities in different ecosystems ranging from oceans to the human microbiome. Developments in several bioinformatics approaches are also discussed in context of microbial metagenomics that include taxonomic systems, sequence databases, …

Thalassiosira Spp. Community Composition Shifts In Response To Chemical And Physical Forcing In The Northeast Pacific Ocean, P. Dreux Chappell, Leann P. Whitney, Traci L. Haddock, Susanne Menden-Deuer, Eric G. Roy, Mark L. Wells, Bethany D. Jenkins

Biological Sciences Faculty Publications

Diatoms are genetically diverse unicellular photosynthetic eukaryotes that are key primary producers in the ocean. Many of the over 100 extant diatom species in the cosmopolitan genus Thalassiosira are difficult to distinguish in mixed populations using light microscopy. Here, we examine shifts in Thalassiosira spp. composition along a coastal to open ocean transect that encountered a 3-month-old Haida eddy in the northeast Pacific Ocean. To quantify shifts in Thalassiosira species composition, we developed a targeted automated ribosomal intergenic spacer analysis (ARISA) method to identify Thalassiosira spp. in environmental samples. As many specific fragment lengths are indicative of individual Thalassiosira spp., …

Expression And Characterization Of The Major Capsid Protein (Mcp) Of A Giant Marine Virus: Cafeteria Roenbergensis Virus, Sayan Chakraborty

Open Access Theses & Dissertations

The oceans play significant roles in maintaining the climate on Earth and providing nutrients to the whole biosphere. Oceanic microbes produce approximately half of the Earth's oxygen. It has been shown that the populations of microbial communities in oceans are largely regulated by viral infection and thus affect the marine ecosystem. Cafeteria roenbergensis Virus (CroV) is a giant marine virus with a linear, double stranded, and AT-rich DNA genome. The genome of CroV has a size of 744kb and encodes for 544 predicted genes. CroV derived its name from its host, a unicellular marine zooplankton Cafeteria roenbergensis (Cro) that is …

Sumoylation Exerts Minimal Effects On The Splicing Regulatory Activity Of The Influenza A Virus Non-Structural Protein Ns1, Griselda Melendez

Open Access Theses & Dissertations

One of the greatest challenges facing the development of a universal treatment for influenza infection is the virus's ability to mutate rapidly and produce new antigenic properties. Targeting the viral components of one strain does not ensure that the treatment will be effective with a newly developed strain. One alternative would be to develop therapies that target cellular factors the virus depends on for survivability. One of these factors is the cellular SUMOylation system. We have previously demonstrated that the Small Ubiquitin-like MOdifier (SUMO) interacts with the influenza virus by SUMOylating several viral proteins and by affecting the interferon blocking …

Role Of Post-Translational Modifications In The Hiv Cofactor Activity Of Ledgf/P75, Denisse Adriana Gutierrez

Open Access Theses & Dissertations

see document.

Validation Of N-Myristoyltransferase As Potential Chemotherapeutic Target In Chagas Disease, Linda Herrera

Open Access Theses & Dissertations

The protozoan parasite Trypanosoma cruzi is the etiological agent of Chagas disease, a problem endemic to Central and South America. In recent years, this neglected infectious disease has become a global health concern. The only clinically available drugs for the chemotherapy of Chagas disease have important disadvantages such as, high toxicity, strain resistance and variable efficacy. Therefore, there is an urgent need for the development of new antichagasic agents. The enzyme N-myristoyltransferase (NMT) has been characterized in a range of eukaryotes, from Saccharomyces cerevisae to Homo sapiens. Moreover, NMT has been shown to be essential in protozoan parasites, including Leishmania …

The Threat Of Domestic Bioterrorism: Fact Or Fiction, Stacy M. Langston

Open Access Theses & Dissertations

The threat of a domestic bioterrorist attack can be a daunting issue to cover. Using the analytic technique What If? Analysis a scenario was created for a domestic bioterrorism attack in Houston, TX. Indicators were developed to determine how to mitigate and respond to the attack. Recommendations were provided following the attack that can be used to prevent future attacks that were conducted in the scenario. Having a hindsight view of an attack is the best way to prevent and respond to the attack.

Managing Soil Microbial Communities With Organic Amendments To Promote Soil Aggregate Formation And Plant Health, Shawn T. Lucas

Theses and Dissertations--Plant and Soil Sciences

The effects of managing soil with organic amendments were examined with respect to soil microbial community dynamics, macroaggregate formation, and plant physio-genetic responses. The objective was to examine the possibility of managing soil microbial communities via soil management, such that the microbial community would provide agronomic benefits. In part one of this research, effects of three amendments (hairy vetch residue, manure, compost) on soil chemical and microbial properties were examined relative to formation of large macroaggregates in three different soils. Vetch and manure promoted fungal proliferation (measured via two biomarkers: fatty acid methyl ester 18:2ω6c and ergosterol) and also stimulated …

Type I Interferon Activation Of Natural Killer (Nk) Cells By Cytomegalovirus (Cmv) And Their Interaction With Dendritic (Dc) And Nkt Cells, Howaida A. Oulad Abdelati

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In our current study the roles of natural killer (NK) cells in regulation of the acute phase of murine cytomegalovirus (MCMV) infection were demonstrated. NK cells utilize perforin and gamma interferon to kill MCMV infected cells. Activation of NK cells is controlled by the balance between inhibitory and activation receptors and modulated by cytokines produced from the infected cells. Type I interferons are produced mainly by plasmacytoid dendritic cells (PDCs). Type I interferons have a substantial role in enhancing NK cells cytotoxic activity and NK cells proliferation and maintain cell survival through STAT mediated signaling pathway. IL-12 produced by dendritic …

Characterization Of Brer Interaction With The Bile Response Promoters Breab And Brer In Vibrio Cholerae, Francisca A. Cerda-Maira, Gabriela Kovacikova, Brooke A. Jude, Karen Skorupski, Ronald Taylor

Dartmouth Scholarship

The Vibrio cholerae BreR protein is a transcriptional repressor of the breAB efflux system operon, which encodes proteins involved in bile resistance. In a previous study (F. A. Cerda-Maira, C. S. Ringelberg, and R. K. Taylor, J. Bacteriol. 190:7441-7452, 2008), we used gel mobility shift assays to determine that BreR binds at two independent binding sites at the breAB promoter and a single site at its own promoter. Here it is shown, by DNase I footprinting and site-directed mutagenesis, that BreR is able to bind at a distal and a proximal site in the breAB promoter. However, only one of …

Inhibition Of The Host Translation Shutoff Response By Herpes Simplex Virus 1 Triggers Nuclear Envelope-Derived Autophagy, Kerstin Radtke, Luc English, Christiane Rondeau, David Leib

Dartmouth Scholarship

Macroautophagy is a cellular pathway that degrades intracellular pathogens and contributes to antigen presentation. Herpes simplex virus 1 (HSV-1) infection triggers both macroautophagy and an additional form of autophagy that uses the nuclear envelope as a source of membrane. The present study constitutes the first in-depth analysis of nuclear envelope-derived autophagy (NEDA). We established LC3a as a marker that allowed us to distinguish between NEDA and macroautophagy in both immunofluorescence and flow cytometry. NEDA was observed in many different cell types, indicating that it is a general response to HSV-1 infection. This autophagic pathway is known to depend on the …

Mitochondrial Dna Instability In Cells Lacking Aconitase Correlates With Iron Citrate Toxicity, Zhengchang Liu, Fei Xiao, Zhejun Dong, Tammy Pracheil, Muhammad Farooq

Biological Sciences Faculty Publications

Aconitase, the second enzyme of the tricarboxylic acid cycle encoded by ACO1 in the budding yeast Saccharomyces cerevisiae, catalyzes the conversion of citrate to isocitrate. aco1Δ results in mitochondrial DNA (mtDNA) instability. It has been proposed that Aco1 binds to mtDNA and mediates its maintenance. Here we propose an alternative mechanism to account for mtDNA loss in aco1Δ mutant cells. We found that aco1Δ activated the RTG pathway, resulting in increased expression of genes encoding citrate synthase. By deleting RTG1, RTG3, or genes encoding citrate synthase, mtDNA instability was prevented in aco1Δ mutant cells. Increased activity of citrate synthase leads …

Human Cytomegalovirus Us17 Locus Fine-Tunes Innate And Intrinsic Immune Responses, Stephen James Gurczynski

Wayne State University Dissertations

HCMV employs numerous strategies to combat, subvert, or co-opt host immunity. One evolutionary strategy for this involves "capture" of a host gene and then its successive duplication and divergence, forming a gene family, many of which have immunomodulatory activities. The HCMV US12 family consists of ten tandemly arranged sequence-related genes in the unique short region of the HCMV genome (US12-US21). Each gene encodes a protein possessing seven predicted transmembrane domains, and patches of sequence similarity with cellular GPCRs and the bax inhibitor-1 family of anti-apoptotic proteins. We show that one member, US17, plays an important role during virion maturation. Microarray …

Critical Events In Human Metapneumovirus Infection: From Entry To Egress, Brent A. Hackett

Theses and Dissertations--Molecular and Cellular Biochemistry

Human metapneumovirus (HMPV) is a respiratory pathogen in Paramyxovirus family that demonstrates extremely high morbidity in the population, with most individuals having been infected by the age of five. Despite the prevalence of this negative-sense RNA virus in the population for decades, it was only identified in 2001. As such, there is currently no specific treatment for HMPV and the potentially severe consequences of infection for elderly and immunocompromised individuals and particularly infants make development of antivirals targeting HMPV of high significance. HMPV constitutes a quarter of all respiratory hospitalizations among infants, placing it second only to RSV, in addition …

Amp-Activated Protein Kinase Knockdown In Labyrinthine Trophoblast Cells Results In Altered Morphology And Function, Erica Ashton Kayleigh Carey

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The placenta is a transient organ that develops upon initiation of pregnancy and is essential for fetal development and survival. The rodent placenta consists of three layers with predominantly analogous cell types in the human placenta. The labyrinth layer, which lies closest to the fetus, facilitates nutrient and waste exchange between mother and baby. Abnormalities of the placenta may occur as a result of cellular stress and have been associated with the pregnancy-associated disorders, intrauterine growth restriction and placental insufficiency. AMP-activated protein kinase (AMPK) is a master sensor of cellular stress and changes in AMPK expression or activation could be …

The Effect Of Hsv-1 Infection On Differentiated And Polarized U937 Cells, Allolo Dreiwish Aldreiwish

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Herpes simplex virus type 1 (HSV-1) challenges the host immune system through several mechanisms (Frey, et al., 2009). In vitro, U937 cells (human macrophage-like precursor cell line) are not susceptible to HSV-1 infection when they are not differentiating (Lopez-Guerrero and Alonso, 1997). Differentiation of these cells resistance can abrogates their resistance to HSV-1 (Tenney and Morahan, 1991). In this study, we examined the effect of HSV-1 infection on differentiated and polarized U937 cells. U937 cells are differentiated to M0 cells.

Then, M0 cells are polarized to distinct phenotypes, M1 or M2. M1 are proinflammatory macrophages while M2 are anti-inflammatory cells. …

Establishment Of A Quiscence Herpes Simplex Type 1 Infection In L929 Fibroblasts And Neuro-2a Cells By A Nucleoside Analogue Acyclovir, Noura Shaklawoon

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Herpes simplex type 1 (HSV-1) quiescent infection was established in L929 cells, murine fibroblasts, and in Neuro-2A (N2A) cells, mouse neuroblastoma, by treating them with the nucleoside analogue acyclovir (ACV) 24 hours before infection. Subsequent release of virus from the non-productive state was accomplished by treating the cells with the histone deacetylase inhibitor trichostatin A (TSA). Treatment of both L929 and N2A cell lines with ACV 24 hours before infection induced protection from HSV-1 cytopathic effect. A quiescent state was confirmed by absence of virus plaques when supernatant fluids from ACV-treated HSV-1 infected cultures were titered on Vero cell monolayers. …