Microbiology Commons^™

Activities Of Methionine-Γ-Lyase In The Acidophilic Archaeon “Ferroplasma Acidarmanus” Strain Fer1, M. A. Khan, Madeline M. Lopez-Munoz, Charles W. Kaspar, Kai F. Hung

Faculty Research & Creative Activity

Biogeochemical processes on exposed pyrite ores result in extremely high levels of sulfuric acid at these locations. Acidophiles that thrive in these conditions must overcome significant challenges, including an environment with proton concentrations at pH 3 or below. The role of sulfur metabolism in the archaeon “Ferroplasma acidarmanus” strain fer1’s ability to thrive in this environment was investigated due to its growth-dependent production of methanethiol, a volatile organic sulfur compound. Two putative sequences for methionine- γ-lyase (EC 4.4.1.11), an enzyme known to carry out α,γ-elimination on L-methionine to produce methanethiol, were identified in fer1. Bioinformatic analyses identified a conserved pyridoxal-5′-phosphate …

Activities Of Methionine-Γ-Lyase In The Acidophilic Archaeon “Ferroplasma Acidarmanus” Strain Fer1, M. Khan, Madeline Lopez-Munoz, Charles Kaspar, Kai Hung

Faculty Research & Creative Activity

Biogeochemical processes on exposed pyrite ores result in extremely high levels of sulfuric acid at these locations. Acidophiles that thrive in these conditions must overcome significant challenges, including an environment with proton concentrations at pH 3 or below. The role of sulfur metabolism in the archaeon “Ferroplasma acidarmanus” strain fer1’s ability to thrive in this environment was investigated due to its growth-dependent production of methanethiol, a volatile organic sulfur compound. Two putative sequences for methionine- γ-lyase (EC 4.4.1.11), an enzyme known to carry out α,γ-elimination on L-methionine to produce methanethiol, were identified in fer1. Bioinformatic analyses identified a conserved pyridoxal-5′-phosphate …

A Review Of G6pd Deficiency In Pakistani Perspective, Bushra Moiz

Department of Pathology and Laboratory Medicine

No abstract provided.

Frequency Of Precancerous Lesions In Endoscopic Gastric Biopsies In Chronic Gastritis, Saroona Haroon, Naveen Faridi, Faisal Rashid Lodhi, Shafaq Mujtaba

Department of Pathology and Laboratory Medicine

Objective:
To determine the frequency of precancerous lesions in endoscopic gastric biopsies of patients with chronic gastritis.STUDY Design: A case series.
Place and duration of study:
Department of Histopathology, Liaquat National Hospital, Karachi, from July 2008 to January 2009.METHODOLOGY: Over 6 months, 375 endoscopic gastric biopsies of patients with age group of 15-65 years having endoscopic chronic gastritis were included. From final biopsy report, basic information like patient demographics and presence of precancerous lesions i.e. activity (chronic active gastritis), atrophy (atrophic gastritis), intestinal metaplasia and dysplasia were recorded on proforma. Results were described as proportions and frequency.
Results:
The frequency …

Modulators Of Symbiotic Outcome In Sinorhizobium Meliloti, Matthew B. Crook

Theses and Dissertations

Microorganisms interact frequently with each other and with higher organisms. This contact and communication takes place at the molecular level. Microbial interactions with eukaryotes can be pathogenic or mutualistic. One of the best-studied symbioses is the complex interaction between nitrogen-fixing soil bacteria, termed rhizobia, and legumes. This symbiosis culminates in the elaboration of a new organ, the root nodule. Many of the molecular signals exchanged between the host plant and the invading rhizobia have been deduced, but there is still much that remains to be discovered. The molecular determinant of host range at the genus level of the plant host …

Cd4 And Cd8 T Cells Directly Recognize Murine Gammaherpesvirus 68-Immortalized Cells And Prevent Tumor Outgrowth, Xiaozhan Liang, Rebecca L. Crepeau, Weijun Zhang, Samuel H. Speck, Edward J. Usherwood

Dartmouth Scholarship

There has been extensive research regarding T cell recognition of Epstein-Barr virus-transformed cells; however, less is known regarding the recognition of B cells immortalized by gamma-2 herpesviruses. Here we show that B cells immortalized by murine gammaherpesvirus 68 (MHV-68, γHV-68) can be controlled by either CD4 or CD8 T cells in vivo. We present evidence for the direct recognition of infected B cells by CD4 and CD8 T cells. These data will help in the development of immunotherapeutic approaches combating gamma-2 herpesvirus-related disease.

Adenosine Triphosphate (Atp) Is A Candidate Signaling Molecule In The Mitochondria-To-Nucleus Retrograde Response Pathway, Zhengchang Liu, Feng Zhang, Janet Thornton, Tammy Pracheil

Biological Sciences Faculty Publications

Intracellular communication from the mitochondria to the nucleus is achieved via the retrograde response. In budding yeast, the retrograde response, also known as the RTG pathway, is regulated positively by Rtg1, Rtg2, Rtg3 and Grr1 and negatively by Mks1, Lst8 and two 14-3-3 proteins, Bmh1/2. Activation of retrograde signaling leads to activation of Rtg1/3, two basic helix-loop-helix leucine zipper transcription factors. Rtg1/3 activation requires Rtg2, a cytoplasmic protein with an N-terminal adenosine triphosphate (ATP) binding domain belonging to the actin/Hsp70/sugar kinase superfamily. The critical regulatory step of the retrograde response is the interaction between Rtg2 and Mks1. Rtg2 binds to …

The Function Of Yeast Pas Kinase, Dr. Julianne Grose

Journal of Undergraduate Research

PAS kinase is a newly discovered member of the nutrient sensing kinases that regulates glucose homeostasis in mice and yeast. The aim of our 2009 MEG “The Function of Yeast PAS kinase” was to characterize the role of a known PAS kinase substrate, Ugp1, as well as to identify novel PAS kinase substrates. We have made significant progress on each of these aims, which has facilitated the preparation of publications, presentations and abstracts. In addition, the findings described below have opened up further research as evidenced by our 2010 and 2011 MEG proposals as well as a 2009 NIH grant …

The Role Of Nuclear Bmp2 (Nbmp2) In Skeletal Muscle, Dr. Laura Bridgewater

Journal of Undergraduate Research

The goal of this project was to characterize the molecular pathway by which nBmp2 disrupts Ca2+ handling in skeletal muscle of nBmp2 mutant mice. Previously, we had worked with Dr. Chad Hancock’s lab to measure muscle function in nBmp2 mutant mice, and those results showed a slowing in the rate at which Ca2+ is pumped from the cytoplasm back into the sarcoplamic reticulum at the conclusion of a skeletal muscle contraction. Our rationale for this MEG study was that characterizing the muscle dysfunction phenotype in the nBmp2 mutant mice would ultimately lead to a molecular level understanding of the functions …

Evidences For Protein-Protein Interactions Between Pstb And Phou In The Phosphate Signaling Complex Of Escherichia Coli, Kristine Dawn Johns

Theses and Dissertations

The PstSCAB2 complex serves the dual function of being a phosphate transporter as well as the primary sensor of phosphate for the Pho regulon. PhoU is an integral protein required for the signal from PstSCAB2 to be transmitted to PhoR. Our hypothesis is that conformational changes of PstSCAB2 during the phosphate transport process are the mechanism by which information about environmental phosphate levels are transduced to the cell. Additionally, we propose that direct protein-protein interactions between PhoU and the alternating conformations of PstSCAB2 mediate PhoU interactions with PhoR. By means of genetic and biochemical approaches, we have found substantial evidence …

Enhanced Phagocytic Activity Of Hiv-Specific Antibodies Correlates With Natural Production Of Immunoglobulins With Skewed Affinity For Fcγr2a And Fcγr2b, Margaret E. Ackerman, Anne-Sophie Dugast, Elizabeth G. Mcandrew, Stephen Tsoukas

Dartmouth Scholarship

While development of an HIV vaccine that can induce neutralizing antibodies remains a priority, decades of research have proven that this is a daunting task. However, accumulating evidence suggests that antibodies with the capacity to harness innate immunity may provide some protection. While significant research has focused on the cytolytic properties of antibodies in acquisition and control, less is known about the role of additional effector functions. In this study, we investigated antibody-dependent phagocytosis of HIV immune complexes, and we observed significant differences in the ability of antibodies from infected subjects to mediate this critical effector function. We observed both …

The Perfect Fit

Colby Magazine

From the classrooms and laboratories of Mayflower Hill, they found their niche in science. Microbiologist Carrie Harwood ’73, transplant surgeon Patrick Wood ’75, and marine biologist Paul Wade ’80 have passion for their professions.

Uncoupling Between Dinitrogen Fixation And Primary Productivity In The Eastern Mediterranean Sea, Eyal Rahav, Barak Herut, Noga Stambler, Edo Bar-Zeev, Margaret R. Mulholland

OES Faculty Publications

In the nitrogen (N)-impoverished photic zones of many oceanic regions, prokaryotic organisms fixing atmospheric dinitrogen (N₂; diazotrophs) supply an essential source of new nitrogen and fuel primary production. We measured dinitrogen fixation and primary productivity (PP) during the thermally stratified summer period in different water regimes of the oligotrophic eastern Mediterranean Sea, including the Cyprus Eddy and the Rhodes Gyre. Low N₂ fixation rates were measured (0.8-3.2μmol N m-2 d-1) excluding 10-fold higher rates in the Rhodes Gyre and Cyprus Eddy (~20μmol N m^-2 d^-1). The corresponding PP increased from east to west (200-2500μmol …

Antioxidant Treatment Regulates The Humoral Immune Response During Acute Viral Infection, Katie E. Crump, P. Kent Langston, Sujana Rajkarnikar, Jason M. Grayson

Biology Faculty Articles

Generation of reactive oxygen intermediates (ROI) following antigen receptor ligation is critical to promote cellular responses. However, the effect of antioxidant treatment on humoral immunity during a viral infection was unknown. Mice were infected with lymphocytic choriomeningitis virus (LCMV) and treated with Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP), a superoxide dismutase mimetic, from days 0 to 8 postinfection. On day 8, at the peak of the splenic response in vehicle-treated mice, virus-specific IgM and IgG antibody-secreting cells (ASC) were decreased 22- and 457-fold in MnTBAP-treated animals. By day 38, LCMV-specific IgG ASC were decreased 5-fold in the bone marrow of drug-treated mice, …

Characterization Of Myxococcus Xanthus Mazf And Implications For A New Point Of Regulation, Tye O. Boynton, Jonathan L. Mcmurry, Lawrence J. Shimkets

Faculty Articles

During development, Myxococcus xanthus cells undergo programmed cell death (PCD) whereby 80% of vegetative cells die. Previously, the MazF RNA interferase has been implicated in this role. Recently, it was shown that deletion of the mazF gene does not eliminate PCD in wild-type strain DK1622 as originally seen in DZF1. To clarify the role of MazF, recombinant enzyme was characterized using a highly sensitive assay in the presence and absence of the proposed antitoxin MrpC. In contrast to previous reports that MrpC inhibits MazF activity, the hydrolysis rate was enhanced in a concentration-dependent manner with MrpC or MrpC2, an N-terminally …

Atypical Glycolysis In Clostridium Thermocellum, Jilai Zhou, Daniel G. Olson, D. Aaron Argyros, Yu Deng, Walter M. Van Gulik, Johannes P. Van Dijken, Lee R. Lynd

Dartmouth Scholarship

Cofactor specificities of glycolytic enzymes in Clostridium thermocellum were studied with cellobiose-grown cells from batch cultures. Intracellular glucose was phosphorylated by glucokinase using GTP rather than ATP. Although phosphofructokinase typically uses ATP as a phosphoryl donor, we found only pyrophosphate (PPi)-linked activity. Phosphoglycerate kinase used both GDP and ADP as phosphoryl acceptors. In agreement with the absence of a pyruvate kinase sequence in the C. thermocellum genome, no activity of this enzyme could be detected. Also, the annotated pyruvate phosphate dikinase (ppdk) is not crucial for the generation of pyruvate from phosphoenolpyruvate (PEP), as deletion of the ppdk gene did …

Progress Realized: Trends In Hiv-1 Viral Load And Cd4 Cell Count In A Tertiary-Care Center From 1999 Through 2011, Howard B. Gale, Manuel D. Rodriguez, Heather J. Hoffman, Debra A. Benator, Fred M. Gordin, Ann M. Labriola, Virginia L. Kan

Epidemiology Faculty Publications

Abstract

Accumulating evidence suggests that alterations in immune function may be important in the etiology of papillary thyroid cancer (PTC). To identify genetic markers in immune-related pathways, we evaluated 3,985 tag single nucleotide polymorphisms (SNPs) in 230 candidate gene regions (adhesion-extravasation-migration, arachidonic acid metabolism/eicosanoid signaling, complement and coagulation cascade, cytokine signaling, innate pathogen detection and antimicrobials, leukocyte signaling, TNF/NF-kB pathway or other) in a case-control study of 344 PTC cases and 452 controls. We used logistic regression models to estimate odds ratios (OR) and calculate one degree of freedom P values of linear trend (PSNP-trend) for the association …

Lysine Biosynthesis In Bacteria: A Metallodesuccinylase As A Potential Antimicrobial Target, Danuta M. Gillner, Daniel P. Becker Ph.D., Richard C. Holz

Chemistry: Faculty Publications and Other Works

In this review, we summarize the recent literature on dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) enzymes, with an emphasis on structure–function studies that provide insight into the catalytic mechanism. Crystallographic data have also provided insight into residues that might be involved in substrate and hence inhibitor recognition and binding. These data have led to the design and synthesis of several new DapE inhibitors, which are described along with what is known about how inhibitors interact with the active site of DapE enzymes, including the efficacy of a moderately strong DapE inhibitor.

Changes In Bacterial Growth Rate Govern Expression Of The Borrelia Burgdorferi Ospc And Erp Infection-Associated Surface Proteins, Brandon L. Jutras, Alicia M. Chenail, Brian Stevenson

Microbiology, Immunology, and Molecular Genetics Faculty Publications

The Lyme disease spirochete controls production of its OspC and Erp outer surface proteins, repressing protein synthesis during colonization of vector ticks but increasing expression when those ticks feed on vertebrate hosts. Early studies found that the synthesis of OspC and Erps can be stimulated in culture by shifting the temperature from 23°C to 34°C, leading to a hypothesis that Borrelia burgdorferi senses environmental temperature to determine its location in the tick-mammal infectious cycle. However, borreliae cultured at 34°C divide several times faster than do those cultured at 23°C. We developed methods that disassociate bacterial growth rate and temperature, allowing …

Control Of Candida Albicans Metabolism And Biofilm Formation By Pseudomonas Aeruginosa Phenazines, Diana K. Morales, Nora Grahl, Chinweike Okegbe, Lars E. P. Dietrich, Nicholas J. Jacobs, Deborah A. Hogan

Dartmouth Scholarship

Candidaalbicanshasdevelopmentalprogramsthatgoverntransitionsbetweenyeastandfilamentousmorphologies and between unattached and biofilm lifestyles. Here, we report that filamentation, intercellular adherence, and biofilm develop- ment were inhibited during interactions between Candida albicans and Pseudomonas aeruginosa through the action of P. aeruginosa-produced phenazines. While phenazines are toxic to C. albicans at millimolar concentrations, we found that lower concentrations of any of three different phenazines (pyocyanin, phenazine methosulfate, and phenazine-1-carboxylate) allowed growth but affected the development of C. albicans wrinkled colony biofilms and inhibited the fungal yeast-to-filament transition. Phenazines impaired C. albicans growth on nonfermentable carbon sources and led to increased production of fer- mentation products (ethanol, glycerol, and …

Phi X 174, David J. Hall

Infectious Pathogens

Phi X 174 database number # 1CD3. Phi X 174 is a virus that infects bacteria and was the first DNA-based genome to be sequenced in 1977. This bacteriophage has a [+] circular single-stranded DNA genome. The assembly of the capsid has been successfully done in vitro and is the focus of many studies on self-assembly, drug delivery and nanotechnology.

Dengue Virus, David J. Hall

Infectious Pathogens

Dengue virus, database # 1THD Dengue fever, is an infectious tropical disease caused by the dengue virus and transmitted by mosquito. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles. In a small proportion of cases the disease develops into the life-threatening dengue hemorrhagic fever. Dengue is a positive strand RNA virus that is part of the flavivirus family. Dengue is an enveloped virus meaning it has a nucleocapsid protecting the RNA and the nucleocapsid is surrounded by lipids (hence the name enveloped).

Human Papilloma Virus 16, David J. Hall

Infectious Pathogens

Human Papilloma virus 16, database# 1DZL Infection by most papillomaviruses is either asymptomatic or causes small benign tumors, known as papillomas or warts (e.g. human papillomavirus HPV6 or HPV11). Papillomas caused by some types, however, such as human papillomaviruses 16 and 18, carry a risk of becoming cancerous. Human papilloma virus is a non-enveloped, double stranded, circular DNA virus.

Hepatitis B, David J. Hall

Infectious Pathogens

Hepatitis B, database # 2g33. Hepatitis B is an infectious inflammatory illness of the liver caused by the hepatitis B virus (HBV). Hepatitis B virus (HBV) is a member of the Hepadnavirus family.The virus particle, (virion) consists of an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. These virions are 42 nM in diameter. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity.

Genetic Regulation Of Mucoidy In Pseudomonas Aeruginosa, T. Ryan Withers

Theses, Dissertations and Capstones

Cystic fibrosis is a genetic disorder that results from mutations in the CF transmembrane conductance regulator gene. These mutations cause a disruption in the chloride transport in mucosal tissues causing the accumulation of dehydrated mucus, and a decrease in the mucocilliary removal of environmental pathogens within the lungs. Additionally, the accumulation of dehydrated mucus within the lungs provides a hospitable environment for various bacteria, including the Gram-negative opportunistic pathogen Pseudomonas aeruginosa. P. aeruginosa uses the overproduction of a surface polysaccharide called alginate to form a biofilm to evade the host’s immunological defenses. The overproduction of alginate, often referred to as …

Activation Of Human Herpesvirus Replication By Apoptosis, Alka Prasad, Jil Remick, Steven L. Zeichner

Pediatrics Faculty Publications

A central feature of herpesvirus biology is the ability of herpesviruses to remain latent within host cells. Classically, exposure to inducing agents, like activating cytokines or phorbol esters that stimulate host cell signal transduction events, and epigenetic agents (e.g., butyrate) was thought to end latency. We recently showed that Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus-8 [HHV-8]) has another, alternative emergency escape replication pathway that is triggered when KSHV's host cell undergoes apoptosis, characterized by the lack of a requirement for the replication and transcription activator (RTA) protein, accelerated late gene kinetics, and production of virus with decreased infectivity. Caspase-3 …

Detection Of Viable Microorganisms Using Propidium Monoazide, Erik J. Mcfarland, Adrian Ponce Dr.

STAR Program Research Presentations

Propidium monoazide (PMA) is a molecular tool used to assess viability of microorganisms. Currently, PMA is thought to discern viability through membrane permeability; PMA enters only membrane compromised cells, irreversibly crosslinks to theirDNAand precipitates theDNAout of solution, preventing it from being amplified during polymerase chain reaction (PCR). Using PMA on a sample of live and dead microorganisms results in only theDNAof living organisms being amplified and identified. Therefore, a comparison ofPCRresults with and without PMA allows one to determine the live fraction and total population, respectively.

Current literature provides conflicting evidence as to the effectiveness of the technique. Our research …

Phenotypic And Genotypic Characterization Of Escherichia Coli Isolated From Untreated Surface Waters, Kai Hung, Steven Daniel, Kristopher Janezic, Blake Ferry, Eric Hendricks, Brian Janiga, Tiffany Johnson, Samantha Murphy, Morgan Roberts, Sarah Scott, Alexandra Theisen

Faculty Research & Creative Activity

A common member of the intestinal microbiota in humans and animals is Escherichia coli. Based on the presence of virulence factors, E. coli can be potentially pathogenic. The focus of this study was to isolate E. coli from untreated surface waters (37 sites) in Illinois and Missouri and determine phenotypic and genotypic diversity among isolates. Water samples positive for fecal coliforms based on the Colisure® test were streaked directly onto Eosin Methylene Blue (EMB) agar (37°C) or transferred to EC broth (44.5°C). EC broth cultures producing gas were then streaked onto EMB agar. Forty-five isolates were identified as E. coli …

Identifying Pathogenic Salmonella Serotypes Isolated From South Central Va Waterways Via Sequential Pcr Analysis, Timothy M. Smith, Jr.

Theses & Honors Papers

Researchers often debate whether all serovars of Salmonella enterica are pathogenic to humans. Broiler houses containing chickens are a major source of Salmonella and serve as potential reservoirs. Therefore, farmers must take substantial measures in order to avoid contamination with their products. The primary objective of the study was to determine whether the four most clinically relevant Salmonella spp. serovars from poultry houses could be isolated from the environmental waterways in Prince Edward and Cumberland Counties of Virginia. The study adapted a serotyping method designed for typing Salmonella to gain a perspective of possible serovars that may be found in …

Genetic Analysis Of The Gene Varpa_4519 Encoding A Nonribosomal Peptide Synthetase Crucial For Surfactant Production In Variovorax Paradoxus Eps, Richard John Fredendall

Theses Digitization Project

This study investigated swarming by Variovoras paradoxus EPS to understand the genes involved and the mechanisms for swarming motility. Swarming motility is defined as a movement on a surface requiring surfactant and flagella. Swarming is a differentiation process in which bacteria enter into an excited state of constant movement. The mechanism for swarming is driven by nutrient factors, and is not based on specific development stages of the bacterial life cycle.