Microbiology Commons^™

2-Heptyl-4-Quinolone, A Precursor Of The Pseudomonas Quinolone Signal Molecule, Modulates Swarming Motility In Pseudomonas Aeruginosa, Dae-Gon Ha, Judith H. Merritt, Thomas H. Hampton, James T. Hodgkinson, Matej Janecek, David R. Spring, Martin Welch, George A. O'Toole

Dartmouth Scholarship

Pseudomonas aeruginosa is an opportunistic pathogen capable of group behaviors, including biofilm formation and swarming motility. These group behaviors are regulated by both the intracellular signaling molecule c-di-GMP and acylhomoserine lactone quorum-sensing systems. Here, we show that the Pseudomonas quinolone signal (PQS) system also contributes to the regulation of swarming motility. Specifically, our data indicate that 2-heptyl-4-quinolone (HHQ), a precursor of PQS, likely induces the production of the phenazine-1-carboxylic acid (PCA), which in turn acts via an as-yet-unknown downstream mechanism to repress swarming motility. We show that this HHQ- and PCA-dependent swarming repression is apparently independent of changes in global …

High Ethanol Titers From Cellulose By Using Metabolically Engineered Thermophilic, Anaerobic Microbes, D. Aaron Argyros, Shital A. Tripathi, Trisha F. Barrett, Stephen R. Rogers, Lawrence F. Feinberg, Daniel G. Olson, Justin M. Foden, Bethany B. Miller, Lee R. Lynd, David A. Hogsett, Nicky C. Caiazza

Dartmouth Scholarship

This work describes novel genetic tools for use in Clostridium thermocellum that allow creation of unmarked mutations while using a replicating plasmid. The strategy employed counter-selections developed from the native C. thermocellum hpt gene and the Thermoanaerobacterium saccharolyticum tdk gene and was used to delete the genes for both lactate dehydrogenase (Ldh) and phosphotransacetylase (Pta). The Δldh Δpta mutant was evolved for 2,000 h, resulting in a stable strain with 40:1 ethanol selectivity and a 4.2-fold increase in ethanol yield over the wild-type strain. Ethanol production from cellulose was investigated with an engineered coculture of organic acid-deficient engineered strains of …

Ecology And Genetic Structure Of A Northern Temperate Vibrio Cholerae Population Related To Toxigenic Isolates, Brian M. Schuster, Anna L. Tyzik, Rachel A. Donner, Megan J. Striplin, Salvador Almagro-Moreno

Dartmouth Scholarship

Although Vibrio cholerae is an important human pathogen, little is known about its populations in regions where the organism is endemic but where cholera disease is rare. A total of 31 independent isolates confirmed as V. cholerae were collected from water, sediment, and oysters in 2008 and 2009 from the Great Bay Estuary (GBE) in New Hampshire, a location where the organism has never been detected. Environmental analyses suggested that abundance correlates most strongly with rainfall events, as determined from data averaged over several days prior to collection. Phenotyping, genotyping, and multilocus sequence analysis (MLSA) revealed a highly diverse endemic …

Coordinated Regulation By Agra, Sara, And Sarr To Control Agr Expression In Staphylococcus Aureus, Dindo Reyes, Diego O. Andrey, Antoinette Monod, William L. Kelley, Gongyi Zhang, Ambrose L. Cheung

Dartmouth Scholarship

The agr locus of Staphylococcus aureus is composed of two divergent transcripts (RNAII and RNAIII) driven by the P2 and P3 promoters. The P2-P3 intergenic region comprises the SarA/SarR binding sites and the four AgrA boxes to which AgrA binds. We reported here the role of AgrA, SarA, and SarR on agr P2 and P3 transcription. Using real-time reverse transcription (RT)-PCR and promoter fusion studies with selected single, double, triple, and complemented mutants, we showed that AgrA is indispensable to agr P2 and P3 transcription, whereas SarA activates and SarR represses P2 transcription. In vitro runoff transcription assays revealed that …

Isolated Adult Hypoganglionosis Presenting As Sigmoid Volvulus: A Case Report., Irfan Qadir, Muhammad Musa Salick, Abrar Barakzai, Hasnain Zafar

Department of Surgery Docs

Introduction:Isolated hypoganglionosis is a rare cause of intestinal innervation defects. It is characterized by sparse and small myenteric ganglia, absent or low acetylcholinesterase activity in the lamina propria and hypertrophy of the muscularis mucosae, principally in the region of the colon and rectum. It accounts for 5% of all intestinal neuronal malformations. To the best of our knowledge, only 92 cases of isolated hypoganglionosis were reported from 1978 to 2009. Isolated hypoganglionosis usually manifests as enterocolitis or poor bowel function, and is diagnosed in infancy or childhood. We report the first case of isolated hypoganglionosis presenting with sigmoid volvulus …

Toxoplasma Gondii Rhoptry Kinase Rop16 Activates Stat3 And Stat6 Resulting In Cytokine Inhibition And Arginase-1-Dependent Growth Control, Barbara A. Butcher, Barbara A. Fox, Leah M. Rommereim, Sung Guk Kim, Kirk J. Maurer, Felix Yarovinsky, De'broski R. Herbert, David J. Bzik, Eric Y. Denkers

Dartmouth Scholarship

The ROP16 kinase of Toxoplasma gondii is injected into the host cell cytosol where it activates signal transducer and activator of transcription (STAT)-3 and STAT6. Here, we generated a ROP16 deletion mutant on a Type I parasite strain background, as well as a control complementation mutant with restored ROP16 expression. We investigated the biological role of the ROP16 molecule during T. gondii infection. Infection of mouse bone marrow-derived macrophages with rop16-deleted (ΔROP16) parasites resulted in increased amounts of IL-12p40 production relative to the ROP16-positive RH parental strain. High level IL-12p40 production in ΔROP16 infection was dependent on the host …

Group Size And Nest Spacing Affect Buggy Creek Virus (Togaviridae: Alphavirus) Infection In Nestling House Sparrows, Valerie A. Brown, Charles R. Brown

Papers in Ornithology

The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the swallow bug (Oeciacus vicarius) to the cliff swallow (Petrochelidon pyrrhonota) and the introduced house sparrow (Passer domesticus) that has recently invaded swallow nesting colonies. The virus has little impact on cliff swallows, but house sparrows are seriously …

Three-Dimensional Structure And Function Of The Paramecium Bursaria Chlorella Virus Capsid, Xinzheng Zhang, Ye Xiang, David Dunigan, Thomas Klose, Paul R. Chipman, James L. Van Etten, Michael G. Rossmann

Nebraska Center for Virology: Faculty Publications

A cryoelectron microscopy 8.5 Å resolution map of the 1,900 Å diameter, icosahedral, internally enveloped Paramecium bursaria chlorella virus was used to interpret structures of the virus at initial stages of cell infection. A fivefold averaged map demonstrated that two minor capsid proteins involved in stabilizing the capsid are missing in the vicinity of the unique vertex. Reconstruction of the virus in the presence of host chlorella cell walls established that the spike at the unique vertex initiates binding to the cell wall, which results in the enveloped nucleocapsid moving closer to the cell. This process is concurrent with the …

Activation Of Jnk Signaling Mediates Amyloid-Ss- Dependent Cell Death, Meghana Tare, Rohan Modi, Jaison Nainaparampil, Oorvashi Roy Puli, Shimpi Bedi, Pedro Fernandez-Funez, Madhuri Kango-Singh, Amit Singh

Biology Faculty Publications

Background: Alzheimer's disease (AD) is an age related progressive neurodegenerative disorder. One of the reasons for Alzheimer's neuropathology is the generation of large aggregates of Aß42 that are toxic in nature and induce oxidative stress, aberrant signaling and many other cellular alterations that trigger neuronal cell death. However, the exact mechanisms leading to cell death are not clearly understood.

Methodology/Principal Findings: We employed a Drosophila eye model of AD to study how Aß42 causes cell death. Misexpression of higher levels of Aß42 in the differentiating photoreceptors of fly retina rapidly induced aberrant cellular phenotypes and cell death. We found that …

Type Ii Toxoplasma Gondii Ku80 Knockout Strains Enable Functional Analysis Of Genes Required For Cyst Development And Latent Infection, Barbara A. Fox, Alejandra Falla, Leah M. Rommereim, Tadakimi Tomita

Dartmouth Scholarship

Type II Toxoplasma gondii KU80 knockouts (Δku80) deficient in nonhomologous end joining were developed to delete the dominant pathway mediating random integration of targeting episomes. Gene targeting frequency in the type II Δku80 Δhxgprt strain measured at the orotate (OPRT) and the uracil (UPRT) phosphoribosyltransferase loci was highly efficient. To assess the potential of the type II Δku80 Δhxgprt strain to examine gene function affecting cyst biology and latent stages of infection, we targeted the deletion of four parasite antigen genes (GRA4, GRA6, ROP7, and tgd057 …

The Fecal Viral Flora Of Wild Rodents, Tung G. Phan, Beatrix Kapusinszky, Chunlin Wang, Robert K. Rose, Howard L. Lipton, Eric L. Delwart

Biological Sciences Faculty Publications

The frequent interactions of rodents with humans make them a common source of zoonotic infections. To obtain an initial unbiased measure of the viral diversity in the enteric tract of wild rodents we sequenced partially purified, randomly amplified viral RNA and DNA in the feces of 105 wild rodents (mouse, vole, and rat) collected in California and Virginia. We identified in decreasing frequency sequences related to the mammalian viruses families Circoviridae, Picobirnaviridae, Picornaviridae, Astroviridae, Parvoviridae, Papillomaviridae, Adenoviridae, and Coronaviridae. Seventeen small circular DNA genomes containing one or two replicase genes distantly related to the Circoviridae representing several potentially …

The Role Of Human Ubc9 During The Human Immunodeficiency Virus Replication Cycle, Christopher R. Bohl

School of Biological Sciences: Dissertations, Theses, and Student Research

Human immunodeficiency virus type 1 (HIV-1) is a retrovirus and the causative agent of the acquired immune deficiency syndrome (AIDS) pandemic. The retrovirus replication cycle is divided into early infectious events, which involve the infection and integration of the viral DNA into target cell chromosomes; and late events, which involve the expression of viral genes and assembly of infectious virions. To complete the replication cycle, HIV-1 utilizes various cellular pathways.

We identified the Ubc9 E2 SUMO conjugating enzyme as a HIV-1 Gag interaction partner. When this interaction was disrupted in HIV-1 producer cells by Ubc9 siRNA, the virus that was …

Presence Of Rd149 Deletions In M. Tuberculosis Central Asian Strain 1 Isolates Affect Growth And Tnfalpha Induction In Thp-1 Monocytes., Akber Kanji, Zahra Hasan, Mehnaz Tanveer, Raunaq Mahboob, Sana Jafri, Rumina Hasan

Department of Pathology and Laboratory Medicine

Central Asian Strain 1 (CAS1) is the prevalent Mycobacterium tuberculosis genogroup in South Asia. CAS1 strains carry deletions in RD149 and RD152 regions. Significance of these deletions is as yet unknown. We compared CAS1 strains with RD149 and concurrent RD149-RD152 deletions with CAS1 strains without deletions and with the laboratory reference strain, M. tuberculosis H37Rv for growth and for induction of TNFα, IL6, CCL2 and IL10 in THP-1 cells. Growth of CAS1 strains with deletions was slower in broth (RD149; p = 0.024 and RD149-RD152; p = 0.025) than that of strains without deletions. CAS1 strains with RD149 deletion strains …

Human Pathogen Shown To Cause Disease In The Threatened Elkhorn Coral Acropora Palmata, Kathryn Patterson Sutherland, Sameera Shaban, Jessica L. Joyner, James W. Porter, Erin K. Lipp

Faculty Publications

Coral reefs are in severe decline. Infections by the human pathogen Serratia marcescens have contributed to precipitous losses in the common Caribbean elkhorn coral, Acropora palmata, culminating in its listing under the United States Endangered Species Act. During a 2003 outbreak of this coral disease, called acroporid serratiosis (APS), a unique strain of the pathogen, Serratia marcescens strain PDR60, was identified from diseased A. palmata, human wastewater, the non-host coral Siderastrea siderea and the corallivorous snail Coralliophila abbreviata. In order to examine humans as a source and other marine invertebrates as vectors and/or reservoirs of the APS pathogen, challenge experiments …

Studies Of Food Thickeners In Nigeria For Contamination By Aflatoxigenic Forms Of Aspergillus And Their Detection By Pcr, G. I. Okwu, Premila Achar, Michael J. Ikenebomeh, S. Y. Sreenivasa

Faculty Articles

This paper reports the contamination of ready-to-use food thickeners, collected from the South-East geo-political zone in Nigeria, by aflatoxigenic form of Aspergillus species. A total of 150 samples from different open markets were observed for fungal contamination by using serial dilution-spread plate method. Although, Aspergillus, Fusarium and Penicillium were the most frequently isolated fungi, Aspergillus species were found to be the most prevalent in all the samples. Furthermore, Aspergillus flavus and Aspergillus parasiticus produced aflatoxin on yeast extract sucrose (YES) media incubated for 10 to 15 days at 27°C in a CO₂ incubator. Aspergillus niger showed no sign of …

Combination Of Virb Binding Site Mutations To Evaluate Collective Impact On Icsp Promoter Activity In Shigella Flexneri, Pashtana Usufuzy, Juan C. Duhart, Maria I. Castellanos, Helen Wing

Undergraduate Research Opportunities Program (UROP)

Shigella flexneri is a gram-negative, invasive bacterial pathogen that afflicts the human colonic epithelium, causing shigellosis, an illness triggering severe dysentery. The World Health Organization cites the disease burden of shigellosis near 90 million episodes and 108,000 deaths per year.

The motility and spread of Shigella is modulated by icsP, a virulence gene. The transcription factor VirB positively regulates many virulence genes encoded by the Shigella virulence plasmid. Two distal binding sites of VirB have been shown to regulate the promoter activity of icsP, despite their location of more than 1 kb upstream of the transcription start site. Five VirB …

Identification Of Nitrifying Bacteria Contained In A Commercial Inoculant Using Molecular Biology Techniques, Anthony Harrington, John Perry, Penny S. Amy

Undergraduate Research Opportunities Program (UROP)

Nitrifying bacteria play an important role in aquatic and terrestrial environments through the nitrogen cycle. Nitrification, one of the processes of the nitrogen cycle, refers to the oxidation of ammonia to nitrate. This process requires two types of chemoautotrophic bacteria, ammonia-oxidizing bacteria (AOB), and nitrite-oxidizing bacteria (NOB). These bacteria are essential in maintaining an optimal environment for plants and aquatic organisms, such as fish. Current applications of nitrifiers include: inoculants for aquariums, biofertilizers, and nitrogen removal in wastewater treatment plants. This study wants to identify a consortium of nitrifers that can be used to produce sufficient nitrate for plants in …

Biological Effects On Serpentinite Weathering, Mary H. Evert, Julie Baumeister, Elisabeth Hausrath

Undergraduate Research Opportunities Program (UROP)

Serpentinites, perhaps more than any other rock type, control the composition and evolution of the development of the surrounding ecosystems. The bulk chemistry of serpentinite rocks, high in Mg and trace elements, and low in nutrients such as Ca, K, P, and N, causes an extreme and stressful environment for ecosystems. However, the role that those serpentine ecosystems play in development of serpentine soils has not been examined.

Due to the unusual chemistry of serpentine soils, serpentine ecosystems have deeper and better-developed root systems than other ecosystems. The rhizosphere of serpentine systems, documented to produce abundant organic acids and siderophores, …

Inactivation Of Spo0a Gene Increases Stationary Phase Mutagenesis In Bacillus Subtilis, Denisse Reyes, Amanda Prisbrey, Holly Martin, Eduardo Robleto

Undergraduate Research Opportunities Program (UROP)

Stationary phase mutagenesis occurs when a population of cells acquires mutations conferring escape from nongrowing or stress conditions. This type of mutations is observed in nutritionally starved cells. Because the mutations occur after the onset of stress and in cells that are in non-replicative conditions, elucidating the underlying mechanisms contributes novel views to the process of evolution and apply to the formation of cancer in human cells and antibiotic resistance in microbial pathogens. Studies have shown that in Bacillus subtilis, the Mfd protein which is a transcription repair coupling factor is necessary for this phenomenon to occur. Here, we investigate …

Synthesis Of Chimeric Receptors Essential For Spore Germination, Christopher Yip, Christian Ross, Eduardo Robleto, Ernesto Abel-Santos

Undergraduate Research Opportunities Program (UROP)

Various species of bacteria have been reported to form an endospore, a metabolically dormant cell, during times of nutrient deficiencies and extreme stress. These said structures are outstandingly resistant to harsh chemicals, extreme temperatures, and can revert back to a metabolically active cell, through a process known as germination, when the necessary conditions are met. The rigid membrane of the endospore contains various germination (Ger) receptors which sense the external environment for necessary metabolites and germinants. Ger receptors are encoded by tricistronic operons that produce three distinct membrane proteins, the A, B, and C subunits. Although the function of the …