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Full-Text Articles in Medicine and Health Sciences
Mcl1 Enhances The Survival Of Cd8+ Memory T Cells After Viral Infection, Jingang Gui, Zhuting Hu, Ching-Yi Tsai, Tian Ma, Yan Song, Amanda Morales, Li-Hao Huang, Ethan Dmitrovsky, Ruth Craig, Edward Usherwood
Mcl1 Enhances The Survival Of Cd8+ Memory T Cells After Viral Infection, Jingang Gui, Zhuting Hu, Ching-Yi Tsai, Tian Ma, Yan Song, Amanda Morales, Li-Hao Huang, Ethan Dmitrovsky, Ruth Craig, Edward Usherwood
Dartmouth Scholarship
Viral infection results in the generation of massive numbers of activated effector CD8+ T cells that recognize viral components. Most of these are short-lived effector T cells (SLECs) that die after clearance of the virus. However, a small proportion of this population survives and forms antigen-specific memory precursor effector cells (MPECs), which ultimately develop into memory cells. These can participate in a recall response upon reexposure to antigen even at protracted times postinfection. Here, antiapoptotic myeloid cell leukemia 1 (MCL1) was found to prolong survival upon T cell stimulation, and mice expressing human MCL1 as a transgene exhibited a skewing …
Intrinsic Innate Immunity Fails To Control Herpes Simplex Virus And Vesicular Stomatitis Virus Replication In Sensory Neurons And Fibroblasts, Pamela C. Rosato, David A. Leib
Intrinsic Innate Immunity Fails To Control Herpes Simplex Virus And Vesicular Stomatitis Virus Replication In Sensory Neurons And Fibroblasts, Pamela C. Rosato, David A. Leib
Dartmouth Scholarship
Herpes simplex virus 1 (HSV-1) establishes lifelong latent infections in the sensory neurons of the trigeminal ganglia (TG), wherein it retains the capacity to reactivate. The interferon (IFN)-driven antiviral response is critical for the control of HSV-1 acute replication. We therefore sought to further investigate this response in TG neurons cultured from adult mice deficient in a variety of IFN signaling components. Parallel experiments were also performed in fibroblasts isolated concurrently. We showed that HSV-1 replication was comparable in wild-type (WT) and IFN signaling-deficient neurons and fibroblasts. Unexpectedly, a similar pattern was observed for the IFN-sensitive vesicular stomatitis virus (VSV). …
Structural Features Of The Pseudomonas Fluorescens Biofilm Adhesin Lapa Required For Lapg-Dependent Cleavage, Biofilm Formation, And Cell Surface Localization, Chelsea D. Boyd, T. Jarrod Smith, Sofiane El-Kirat-Chatel, Peter D. Newell, Yves F. Dufrêne, George A. O'Toole
Structural Features Of The Pseudomonas Fluorescens Biofilm Adhesin Lapa Required For Lapg-Dependent Cleavage, Biofilm Formation, And Cell Surface Localization, Chelsea D. Boyd, T. Jarrod Smith, Sofiane El-Kirat-Chatel, Peter D. Newell, Yves F. Dufrêne, George A. O'Toole
Dartmouth Scholarship
The localization of the LapA protein to the cell surface is a key step required by Pseudomonas fluorescens Pf0-1 to irreversibly attach to a surface and form a biofilm. LapA is a member of a diverse family of predicted bacterial adhesins, and although lacking a high degree of sequence similarity, family members do share common predicted domains. Here, using mutational analysis, we determine the significance of each domain feature of LapA in relation to its export and localization to the cell surface and function in biofilm formation. Our previous work showed that the N terminus of LapA is required for …
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
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 …
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
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 …
Minor Pilins Of The Type Iv Pilus System Participate In The Negative Regulation Of Swarming Motility, S L. Kuchma, E. F. Griffin, G. A. O'Toole
Minor Pilins Of The Type Iv Pilus System Participate In The Negative Regulation Of Swarming Motility, S L. Kuchma, E. F. Griffin, G. A. O'Toole
Dartmouth Scholarship
Pseudomonas aeruginosa exhibits distinct surface-associated behaviors, including biofilm formation, flagellum-mediated swarming motility, and type IV pilus-driven twitching. Here, we report a role for the minor pilins, PilW and PilX, components of the type IV pilus assembly machinery, in the repression of swarming motility. Mutating either the pilW or pilX gene alleviates the inhibition of swarming motility observed for strains with elevated levels of the intracellular signaling molecule cyclic di-GMP (c-di-GMP) due to loss of BifA, a c-di-GMP-degrading phosphodiesterase. Blocking PilD peptidase-mediated processing of PilW and PilX renders the unprocessed proteins defective for pilus assembly but still functional in c-di-GMP-mediated swarming …
Epoxide-Mediated Cifr Repression Of Cif Gene Expression Utilizes Two Binding Sites In Pseudomonas Aeruginosa, Alicia E. Ballok, Christopher D. Bahl, Emily L. Dolben, Allia K. Lindsay, Jessica D. St. Laurent, Deborah Hogan, Dean Madden, George A. O'Toole
Epoxide-Mediated Cifr Repression Of Cif Gene Expression Utilizes Two Binding Sites In Pseudomonas Aeruginosa, Alicia E. Ballok, Christopher D. Bahl, Emily L. Dolben, Allia K. Lindsay, Jessica D. St. Laurent, Deborah Hogan, Dean Madden, George A. O'Toole
Dartmouth Scholarship
Pseudomonas aeruginosa secretes an epoxide hydrolase virulence factor that reduces the apical membrane expression of ABC transporters such as the cystic fibrosis transmembrane conductance regulator (CFTR). This virulence factor, named CFTR inhibitory factor (Cif), is regulated by a TetR-family, epoxide-responsive repressor known as CifR via direct binding and repression. We identified two sites of CifR binding in the intergenic space between cifR and morB, the first gene in the operon containing the cif gene. We have mapped these binding sites and found they are 27 bp in length, and they overlap the -10 and +1 sites of both the cifR …
Corneal Replication Is An Interferon Response-Independent Bottleneck For Virulence Of Herpes Simplex Virus 1 In The Absence Of Virion Host Shutoff, Tracy J. Pasieka, Vineet D. Menachery, Pamela C. Rosato, David A. Leib
Corneal Replication Is An Interferon Response-Independent Bottleneck For Virulence Of Herpes Simplex Virus 1 In The Absence Of Virion Host Shutoff, Tracy J. Pasieka, Vineet D. Menachery, Pamela C. Rosato, David A. Leib
Dartmouth Scholarship
Herpes simplex viruses lacking the virion host shutoff function (Δvhs) are avirulent and hypersensitive to type I and type II interferon (IFN). In this study, we demonstrate that even in the absence of IFN responses in AG129 (IFN-αβγR−/−) mice, Δvhs remains highly attenuated via corneal infection but is fully virulent via intracranial infection. The data demonstrate that the interferon-independent inherent replication defect of Δvhs has a significant impact upon peripheral replication and neuroinvasion.
Systematic Analysis Of Diguanylate Cyclases That Promote Biofilm Formation By Pseudomonas Fluorescens Pf0-1, Peter D. Newell, Shiro Yoshioka, Kelli L. Hvorecny, Russell D. Monds, George A. O'Toole
Systematic Analysis Of Diguanylate Cyclases That Promote Biofilm Formation By Pseudomonas Fluorescens Pf0-1, Peter D. Newell, Shiro Yoshioka, Kelli L. Hvorecny, Russell D. Monds, George A. O'Toole
Dartmouth Scholarship
Cyclic di-GMP (c-di-GMP) is a broadly conserved, intracellular second-messenger molecule that regulates biofilm formation by many bacteria. The synthesis of c-di-GMP is catalyzed by diguanylate cyclases (DGCs) containing the GGDEF domain, while its degradation is achieved through the phosphodiesterase activities of EAL and HD-GYP domains. c-di-GMP controls biofilm formation by Pseudomonas fluorescens Pf0-1 by promoting the cell surface localization of a large adhesive protein, LapA. LapA localization is regulated posttranslationally by a c-di-GMP effector system consisting of LapD and LapG, which senses cytoplasmic c-di-GMP and modifies the LapA protein in the outer membrane. Despite the apparent requirement for c-di-GMP for …
Non-Identity-Mediated Crispr-Bacteriophage Interaction Mediated Via The Csy And Cas3 Proteins, Kyle C. Cady, George A. O'Toole
Non-Identity-Mediated Crispr-Bacteriophage Interaction Mediated Via The Csy And Cas3 Proteins, Kyle C. Cady, George A. O'Toole
Dartmouth Scholarship
Studies of the Escherichia, Neisseria, Thermotoga, and Mycobacteria clustered regularly interspaced short palindromic repeat (CRISPR) subtypes have resulted in a model whereby CRISPRs function as a defense system against bacteriophage infection and conjugative plasmid transfer. In contrast, we previously showed that the Yersinia-subtype CRISPR region of Pseudomonas aeruginosa strain UCBPP-PA14 plays no detectable role in viral immunity but instead is required for bacteriophage DMS3-dependent inhibition of biofilm formation by P. aeruginosa. The goal of this study is to define the components of the Yersinia-subtype CRISPR region required to mediate this bacteriophage-host interaction. We show that the Yersinia-subtype-specific CRISPR-associated (Cas) proteins …
Role Of Flgt In Anchoring The Flagellum Of Vibrio Cholerae, Raquel M. Martinez, Brooke A. Jude, Thomas J. Kirn, Karen Skorupski, Ronald K. Taylor
Role Of Flgt In Anchoring The Flagellum Of Vibrio Cholerae, Raquel M. Martinez, Brooke A. Jude, Thomas J. Kirn, Karen Skorupski, Ronald K. Taylor
Dartmouth Scholarship
Flagellar motility has long been regarded as an important virulence factor. In Vibrio cholerae, the single polar flagellum is essential for motility as well as for proper attachment and colonization. In this study, we demonstrate that the novel flagellar protein FlgT is involved in anchoring the flagellum to the V. cholerae cell. A screen for novel colonization factors by use of TnphoA mutagenesis identified flgT. An in-frame deletion of flgT established that FlgT is required for attachment, colonization, and motility. Transmission electron microscopy revealed that while the flgT mutant is capable of assembling a phenotypically normal flagellum, …
Characterization Of Two Outer Membrane Proteins, Flgo And Flgp, That Influence Vibrio Cholerae Motility, Raquel M. Martinez, Madushini N. Dharmasena, Thomas J. Kirn, Ronald K. Taylor
Characterization Of Two Outer Membrane Proteins, Flgo And Flgp, That Influence Vibrio Cholerae Motility, Raquel M. Martinez, Madushini N. Dharmasena, Thomas J. Kirn, Ronald K. Taylor
Dartmouth Scholarship
Vibrio cholerae is highly motile by the action of a single polar flagellum. The loss of motility reduces the infectivity of V. cholerae, demonstrating that motility is an important virulence factor. FlrC is the sigma-54-dependent positive regulator of flagellar genes. Recently, the genes VC2206 (flgP) and VC2207 (flgO) were identified as being regulated by FlrC via a microarray analysis of an flrC mutant (D. C. Morris, F. Peng, J. R. Barker, and K. E. Klose, J. Bacteriol. 190:231-239, 2008). FlgP is reported to be an outer membrane lipoprotein required for motility that functions as a colonization factor. The study reported …
Regulation Of The Mazef Toxin-Antitoxin Module In Staphylococcus Aureus And Its Impact On Sigb Expression, Niles P. Donegan, Ambrose L. Cheung
Regulation Of The Mazef Toxin-Antitoxin Module In Staphylococcus Aureus And Its Impact On Sigb Expression, Niles P. Donegan, Ambrose L. Cheung
Dartmouth Scholarship
In Staphylococcus aureus, the sigB operon codes for the alternative sigma factor σBand its regulators that enable the bacteria to rapidly respond to environmental stresses via redirection of transcriptional priorities. However, a full model of σBregulation in S. aureus has not yet emerged. Earlier data has suggested that mazEF, a toxin-antitoxin (TA) module immediately upstream of the sigB operon, was transcribed with the sigB operon. Here we demonstrate that the promoter PmazE upstream of mazEF is essential for full σB activity and that instead of utilizing autorepression typical of TA systems, sigB …
Long-Distance Delivery Of Bacterial Virulence Factors By Pseudomonas Aeruginosa Outer Membrane Vesicles, Jennifer M. Bomberger, Daniel P. Maceachran, Bonita A. Coutermarsh, Siying Ye, George A. O'Toole, Bruce A. Stanton, Frederick M. Ausubel
Long-Distance Delivery Of Bacterial Virulence Factors By Pseudomonas Aeruginosa Outer Membrane Vesicles, Jennifer M. Bomberger, Daniel P. Maceachran, Bonita A. Coutermarsh, Siying Ye, George A. O'Toole, Bruce A. Stanton, Frederick M. Ausubel
Dartmouth Scholarship
Bacteria use a variety of secreted virulence factors to manipulate host cells, thereby causing significant morbidity and mortality. We report a mechanism for the long-distance delivery of multiple bacterial virulence factors, simultaneously and directly into the host cell cytoplasm, thus obviating the need for direct interaction of the pathogen with the host cell to cause cytotoxicity. We show that outer membrane–derived vesicles (OMV) secreted by the opportunistic human pathogen Pseudomonas aeruginosa deliver multiple virulence factors, including β-lactamase, alkaline phosphatase, hemolytic phospholipase C, and Cif, directly into the host cytoplasm via fusion of OMV with lipid rafts in the host plasma …
Characterization Of Mazfsa, An Endoribonuclease From Staphylococcus Aureus, Zhibiao Fu, Niles P. Donegan, Guido Memmi, Ambrose L. Cheung
Characterization Of Mazfsa, An Endoribonuclease From Staphylococcus Aureus, Zhibiao Fu, Niles P. Donegan, Guido Memmi, Ambrose L. Cheung
Dartmouth Scholarship
The mazEF homologs of Staphylococcus aureus, designated mazEF(sa), have been shown to cotranscribe with the sigB operon under stress conditions. In this study, we showed that MazEF(Sa), as with their Escherichia coli counterparts, compose a toxin-antitoxin module wherein MazF(Sa) leads to rapid cell growth arrest and loss in viable CFU upon overexpression. MazF(Sa) is a novel sequence-specific endoribonuclease which cleaves mRNA to inhibit protein synthesis. Using ctpA mRNA as the model substrate both in vitro and in vivo, we demonstrated that MazF(Sa) cleaves single-strand RNA preferentially at the 5' side of the first U or 3' side of the second …
A Serratia Marcescens Oxyr Homolog Mediates Surface Attachment And Biofilm Formation, Robert M. Q. Shanks, Nicholas A. Stella, Eric J. Kalivoda, Megan R. Doe
A Serratia Marcescens Oxyr Homolog Mediates Surface Attachment And Biofilm Formation, Robert M. Q. Shanks, Nicholas A. Stella, Eric J. Kalivoda, Megan R. Doe
Dartmouth Scholarship
OxyR is a conserved bacterial transcription factor with a regulatory role in oxidative stress response. From a genetic screen for genes that modulate biofilm formation in the opportunistic pathogen Serratia marcescens, mutations in an oxyR homolog and predicted fimbria structural genes were identified. S. marcescens oxyR mutants were severely impaired in biofilm formation, in contrast to the hyperbiofilm phenotype exhibited by oxyR mutants of Escherichia coli and Burkholderia pseudomallei. Further analysis revealed that OxyR plays a role in the primary attachment of cells to a surface. Similar to what is observed in other bacterial species, S. marcescens OxyR …
Inverse Regulation Of Biofilm Formation And Swarming Motility By Pseudomonas Aeruginosa Pa14, Nicky C. Caiazza, Judith H. Merritt, Kimberly M. Brothers, George A. O'Toole
Inverse Regulation Of Biofilm Formation And Swarming Motility By Pseudomonas Aeruginosa Pa14, Nicky C. Caiazza, Judith H. Merritt, Kimberly M. Brothers, George A. O'Toole
Dartmouth Scholarship
We previously reported that SadB, a protein of unknown function, is required for an early step in biofilm formation by the opportunistic pathogen Pseudomonas aeruginosa. Here we report that a mutation in sadB also results in increased swarming compared to the wild-type strain. Our data are consistent with a model in which SadB inversely regulates biofilm formation and swarming motility via its ability both to modulate flagellar reversals in a viscosity-dependent fashion and to influence the production of the Pel exopolysaccharide. We also show that SadB is required to properly modulate flagellar reversal rates via chemotaxis cluster IV (CheIV cluster). …
Gammaherpesvirus Persistence Alters Key Cd8 T-Cell Memory Characteristics And Enhances Antiviral Protection, Joshua J. Obar, Shinichiro Fuse, Erica K. Leung, Sarah C. Bellfy, Edward J. Usherwood
Gammaherpesvirus Persistence Alters Key Cd8 T-Cell Memory Characteristics And Enhances Antiviral Protection, Joshua J. Obar, Shinichiro Fuse, Erica K. Leung, Sarah C. Bellfy, Edward J. Usherwood
Dartmouth Scholarship
In herpesvirus infections, the virus persists for life but is contained through T-cell-mediated immune surveillance. How this immune surveillance operates is poorly understood. Recent studies of other persistent infections have indicated that virus persistence is associated with functional deficits in the CD8(+) T-cell response. To test whether this is the case in a herpesvirus infection, we used a mutant murine gammaherpesvirus that is defective in its ability to persist in the host. By comparing the immune response to this virus with a revertant virus that can persist, we were able to dissect the changes in the antiviral CD8(+) T-cell response …
Sara Positively Controls Bap-Dependent Biofilm Formation In Staphylococcus Aureus, María P. Trotonda, Adhar C. Manna, Ambrose L. Cheung, Iñigo Lasa, José R. Penadés
Sara Positively Controls Bap-Dependent Biofilm Formation In Staphylococcus Aureus, María P. Trotonda, Adhar C. Manna, Ambrose L. Cheung, Iñigo Lasa, José R. Penadés
Dartmouth Scholarship
The biofilm-associated protein Bap is a staphylococcal surface protein involved in biofilm formation. We investigated the influence of the global regulatory locus sarA on bap expression and Bap-dependent biofilm formation in three unrelated Staphylococcus aureus strains. The results showed that Bap-dependent biofilm formation was diminished in the sarA mutants by an agr-independent mechanism. Complementation studies using a sarA clone confirmed that the defect in biofilm formation was due to the sarA mutation. As expected, the diminished capacity to form biofilms in the sarA mutants correlated with the decreased presence of Bap in the bacterial surface. Using transcriptional fusion and …
Sara Is An Essential Positive Regulator Of Staphylococcus Epidermidis Biofilm Development, Maria A. Tormo, Miguel Marti, Jaione Valle, Adhar C. Manna
Sara Is An Essential Positive Regulator Of Staphylococcus Epidermidis Biofilm Development, Maria A. Tormo, Miguel Marti, Jaione Valle, Adhar C. Manna
Dartmouth Scholarship
Staphylococcus epidermidis biofilm formation is associated with the production of the polysaccharide intercellular adhesin (PIA)--poly-N-acetylglucosamine polysaccharide (PNAG) by the products of the icaADBC operon. Recent evidence indicates that SarA, a central regulatory element that controls the production of Staphylococcus aureus virulence factors, is essential for the synthesis of PIA/PNAG and the ensuing biofilm development in this species. Based on the presence of a sarA homolog, we hypothesized that SarA could also be involved in the regulation of the biofilm formation process in S. epidermidis. To investigate this, we constructed nonpolar sarA deletions in two genetically unrelated S. epidermidis clinical strains, …
A Three-Component Regulatory System Regulates Biofilm Maturation And Type Iii Secretion In Pseudomonas Aeruginosa, Sherry L. Kuchma, John P. Connolly, George A. O'Toole
A Three-Component Regulatory System Regulates Biofilm Maturation And Type Iii Secretion In Pseudomonas Aeruginosa, Sherry L. Kuchma, John P. Connolly, George A. O'Toole
Dartmouth Scholarship
Biofilms are structured communities found associated with a wide range of surfaces. Here we report the identification of a three-component regulatory system required for biofilm maturation by Pseudomonas aeruginosa strain PA14. A transposon mutation that altered biofilm formation in a 96-well dish assay originally defined this locus, which is comprised of genes for a putative sensor histidine kinase and two response regulators and has been designated sadARS. Nonpolar mutations in any of the sadARS genes result in biofilms with an altered mature structure but do not confer defects in growth or early biofilm formation, swimming, or twitching motility. After …
Identification Of Sarv (Sa2062), A New Transcriptional Regulator, Is Repressed By Sara And Mgra (Sa0641) And Involved In The Regulation Of Autolysis In Staphylococcus Aureus, Adhar C. Manna, Susham S. Ingavale, Marybeth Maloney, Willem Van Wamel, Ambrose L. Cheung
Identification Of Sarv (Sa2062), A New Transcriptional Regulator, Is Repressed By Sara And Mgra (Sa0641) And Involved In The Regulation Of Autolysis In Staphylococcus Aureus, Adhar C. Manna, Susham S. Ingavale, Marybeth Maloney, Willem Van Wamel, Ambrose L. Cheung
Dartmouth Scholarship
The expression of genes involved in the pathogenesis of Staphylococcus aureus is known to be controlled by global regulatory loci, including agr, sarA, sae, arlRS, lytSR, and sarA-like genes. Here we described a novel transcriptional regulator called sarV of the SarA protein family. The transcription of sarV is low or undetectable under in vitro conditions but is significantly augmented in sarA and mgrA (norR or rat) (SA0641) mutants. The sarA and mgrA genes act as repressors of sarV expression, as confirmed by transcriptional fusion and Northern analysis data. Purified SarA and MgrA proteins bound specifically to separate regions of the …
Sadb Is Required For The Transition From Reversible To Irreversible Attachment During Biofilm Formation By Pseudomonas Aeruginosa Pa14, Nicky C. Caiazza, George A. O'Toole
Sadb Is Required For The Transition From Reversible To Irreversible Attachment During Biofilm Formation By Pseudomonas Aeruginosa Pa14, Nicky C. Caiazza, George A. O'Toole
Dartmouth Scholarship
Current models of biofilm formation by Pseudomonas aeruginosa propose that (i) planktonic cells become surface associated in a monolayer, (ii) surface-associated cells form microcolonies by clonal growth and/or aggregation, (iii) microcolonies transition to a mature biofilm comprised of exopolysaccharide-encased macrocolonies, and (iv) cells exit the mature biofilm and reenter the planktonic state. Here we report a new class of P. aeruginosa biofilm mutant that defines the transition from reversible to irreversible attachment and is thus required for monolayer formation. The transposon insertion carried by the sadB199 mutant was mapped to open reading frame PA5346 of P. aeruginosa PA14 and encodes …
Alpha-Toxin Is Required For Biofilm Formation By Staphylococcus Aureus, Nicky C. Caiazza, George A. O'Toole
Alpha-Toxin Is Required For Biofilm Formation By Staphylococcus Aureus, Nicky C. Caiazza, George A. O'Toole
Dartmouth Scholarship
Staphylococcus aureus is a common pathogen associated with nosocomial infections. It can persist in clinical settings and gain increased resistance to antimicrobial agents through biofilm formation. We have found that alpha-toxin, a secreted, multimeric, hemolytic toxin encoded by the hla gene, plays an integral role in biofilm formation. The hla mutant was unable to fully colonize plastic surfaces under both static and flow conditions. Based on microscopy studies, we propose that alpha-hemolysin is required for cell-to-cell interactions during biofilm formation.
Rhamnolipid Surfactant Production Affects Biofilm Architecture In Pseudomonas Aeruginosa Pao1, Mary E. Davey, Nicky C. Caiazza, George A. O'Toole
Rhamnolipid Surfactant Production Affects Biofilm Architecture In Pseudomonas Aeruginosa Pao1, Mary E. Davey, Nicky C. Caiazza, George A. O'Toole
Dartmouth Scholarship
In response to certain environmental signals, bacteria will differentiate from an independent free-living mode of growth and take up an interdependent surface-attached existence. These surface-attached microbial communities are known as biofilms. In flowing systems where nutrients are available, biofilms can develop into elaborate three-dimensional structures. The development of biofilm architecture, particularly the spatial arrangement of colonies within the matrix and the open areas surrounding the colonies, is thought to be fundamental to the function of these complex communities. Here we report a new role for rhamnolipid surfactants produced by the opportunistic pathogen Pseudomonas aeruginosa in the maintenance of biofilm architecture. …
The Cd154/Cd40 Interaction Required For Retrovirus-Induced Murine Immunodeficiency Syndrome Is Not Mediated By Upregulation Of The Cd80/Cd86 Costimulatory Molecules, Kathy A. Green, W. James Cook, Arlene H. Sharpe, William R. Green
The Cd154/Cd40 Interaction Required For Retrovirus-Induced Murine Immunodeficiency Syndrome Is Not Mediated By Upregulation Of The Cd80/Cd86 Costimulatory Molecules, Kathy A. Green, W. James Cook, Arlene H. Sharpe, William R. Green
Dartmouth Scholarship
C57BL/6 (B6) mice infected with LP-BM5 retroviruses develop disease, including an immunodeficiency similar to AIDS. This disease, murine AIDS (MAIDS), is inhibited by in vivo anti-CD154 monoclonal antibody treatment. The similar levels of insusceptibility of CD40−/− and CD154−/− B6 mice indicate that CD154/CD40 molecular interactions are required for MAIDS. CD4+ T and B cells, respectively, provide the CD154 and CD40 expression needed for MAIDS induction. Here, the required CD154/CD40 interaction is shown to be independent of CD80 and CD86 expression: CD80/CD86−/− B6 mice develop MAIDS after LP-BM5 infection.
Type 4 Pilus Biogenesis And Type Ii-Mediated Protein Secretion By Vibrio Cholerae Occur Independently Of The Tonb-Facilitated Proton Motive Force, Niranjan Bose, Shelley M. Payne, Ronald K. Taylor
Type 4 Pilus Biogenesis And Type Ii-Mediated Protein Secretion By Vibrio Cholerae Occur Independently Of The Tonb-Facilitated Proton Motive Force, Niranjan Bose, Shelley M. Payne, Ronald K. Taylor
Dartmouth Scholarship
In Vibrio cholerae, elaboration of toxin-coregulated pilus and protein secretion by the extracellular protein secretion apparatus occurred in the absence of both TonB systems. In contrast, the cognate putative ATPases were required for each process and could not substitute for each other.
The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole
The Growth Of Simian Virus 40 (Sv40) Host Range/Adenovirus Helper Function Mutants In An African Green Monkey Cell Line That Constitutively Expresses The Sv40 Agnoprotein., Terryl P. Stacy, Michele Chamberlain, Susan Carswell, Charles N. Cole
Dartmouth Scholarship
The simian virus 40 T-antigen carboxy-terminal mutants, dlA2459 and dlA2475, are cell line and temperature dependent for growth and plaque formation in monkey kidney cells. Although these mutants did form plaques on BSC-1 cells at 37 degrees C, they were about fivefold less efficient for plaque formation than wild-type simian virus 40. These mutants did not grow in CV-1 cells and did not synthesize agnoprotein in those cells. CV-1 cells which constitutively express the agnoprotein were permissive for mutant plaque formation. However, late mRNAs, virion proteins, and progeny virion yields did not accumulate to wild-type levels during mutant infection of …