Microbiology Commons^™

Isolation By Distance Explains Genetic Structure Of Buggy Creek Virus, A Bird-Associated Arbovirus, Abinash Padhi, Amy T. Moore, Mary Bomberger Brown, Jerome E. Foster, Martin Pfeffer, Charles R. Brown

School of Natural Resources: Faculty Publications

Many of the arthropod-borne viruses (arboviruses) show extensive genetic variability and are widely distributed over large geographic areas. Understanding how virus genetic structure varies in space may yield insight into how these pathogens are adapted to and dispersed by different hosts or vectors, the relative importance of mutation, drift, or selection in generating genetic variability, and where and when epidemics or epizootics are most likely to occur. However, because most arboviruses tend to be sampled opportunistically and often cannot be isolated in large numbers at a given locale, surprisingly little is known about their spatial genetic structure on the local …

Critical Role Of Leucine-Valine Change In Distinct Low Ph Requirements For Membrane Fusion Between Two Related Retrovirus Envelopes, Marceline Côté, Yi-Min Zheng, Kun Li, Shi-Hua Xiang, Lorraine M. Albritton, Shan-Lu Liu

Nebraska Center for Virology: Faculty Publications

Many viruses use a pH-dependent pathway for fusion with host cell membrane, the mechanism of which is still poorly understood. Here we report that a subtle leucine (Leu)-valine (Val) change at position 501 in the envelope glycoproteins (Envs) of two related retroviruses, jaagsiekte sheep retro-virus (JSRV) and enzootic nasal tumor virus (ENTV), is responsible for their distinct low pH requirements for membrane fusion and infection. The Leu and Val residues are predicted to reside within the C-terminal heptad repeat (HR2) region of JSRV and ENTV Envs, particularly proximal to the hairpin turn of the putative six-helix bundle (6HB). Substitution of …

Hiv-1 Effects On Neuropsychological Performance In A Resource-Limited Country, Zambia, Gabriel Holguin, Mwanza Banda, Elizabeth J. Willen, Costantine Malama, Kaseya O. Chiyenu, Victor C. Mudenda, Charles Wood

Nebraska Center for Virology: Faculty Publications

Zambia has substantially been affected by the HIV/AIDS epidemic with prevalence rates at 14% in a population estimated at 12 million. Yet, the extent of HIV-associated neurocognitive disorders (HAND) in this population remains to be clearly understood. A series of culturally appropriate neuropsychological (NP) assessments [International HIV Dementia Scale (IHDS), Color Trails Test 1 and 2, Grooved pegboard Test, and Time Gait Test] were used to test the effects of HIV on NP performance of HIV seropositive and seronegative individuals. Twenty-two percent HIV positive individuals ARV naïve met the criteria for IHDS-defined NP impairment. Gender significantly influenced the performance on …

Characterization Of Species C Human Adenovirus Serotype 6 (Ad6), Eric A. Weaver, Reeti Khare, Mathew L. Hillestad, Donna Palmer, Philip Ng, Michael A. Barry

Nebraska Center for Virology: Faculty Publications

Adenovirus serotype (Ad5) is the most studied Ad. Ad1, 2, and 6 are also members of species C Ad and are presumed to have biologies similar to Ad5. In this work, we have compared the ability of Ad1, 2, 5, and 6 to infect liver and muscle after intravenous and intramuscular injection. We found that Ad6 was surprisingly the most potent at liver gene delivery and that Ad1 and Ad2 were markedly weaker than Ad5 and 6. To understand these differences, we sequenced the Ad6 genome. This revealed that the Ad6 fiber protein is surprisingly three shaft repeats shorter than …

Generation Of A Kupffer Cell-Evading Adenovirus For Systemic And Liver-Directed Gene Transfer, Reeti Khare, Shannon M. May, Francesco Vetrini, Eric A. Weaver, Donna Palmer, Amanda Rosewell, Nathan Grove, Philip Ng, Michael A. Barry

Nebraska Center for Virology: Faculty Publications

As much as 90% of an intravenously (i.v.) injected dose of adenovirus serotype 5 (Ad5) is absorbed and destroyed by liver Kupffer cells. Viruses that escape these cells can then transduce hepatocytes after binding factor X (FX). Given that interactions with FX and Kupffer cells are thought to occur on the Ad5 hexon protein, we replaced its exposed hypervariable regions (HVR) with those from Ad6. When tested in vivo in BALB/c mice and in hamsters, the Ad5/6 chimera mediated >10 times higher transduction in the liver. This effect was not due to changes in FX binding. Rather, Ad5/6 appeared to …

Banf1 Is Required To Maintain The Self-Renewal Of Both Mouse And Human Embryonic Stem Cells, Jesse L. Cox, Sunil K. Mallanna, Briana D. Ormsbee, Michelle Desler, Matthew S. Wiebe, Angie Rizzino

Nebraska Center for Virology: Faculty Publications

Self-renewal is a complex biological process necessary for maintaining the pluripotency of embryonic stem cells (ESCs). Recent studies have used global proteomic techniques to identify proteins that associate with the master regulators Oct4, Nanog, and Sox2 in ESCs or in ESCs during the early stages of differentiation. Through an unbiased proteomic screen, Banf1 was identified as a Sox2- associated protein. Banf1 has been shown to be essential for worm and fly development but, until now, its role in mammalian development and ESCs has not been explored. In this study, we examined the effect of knocking down Banf1 on ESCs. We …

Human Endogenous Retrovirus Transcription Profiles Of The Kidney And Kidney-Derived Cell Lines, Sonja Haupt, Michele Tisdale, Michelle Vincendeau, Mary Anne Clements, David T. Gauthier, Raymond Lance, O. John Demmes, Adriana Tuqueti-Neves, Elfriede Noessner, Christine Leib-Mösch, Alex D. Greenwood

Biological Sciences Faculty Publications

The human genome comprises approximately 8-9% of human endogenous retroviruses (HERVs) that are transcribed with tissue specificity. However, relatively few organs have been examined in detail for individual differences in HERV transcription pattern, nor have tissue-to-cell culture comparisons been frequently performed. Using an HERV-specific DNA microarray, a core HERV transcription profile was established for the human kidney comparing 10 tissue samples. This core represents HERV groups expressed uniformly or nearly so in non-tumour kidney tissue. The profiles obtained from non-tumour tissues were compared to 10 renal tumour tissues (renal cell carcinoma, RCC) derived from the same individuals and additionally, to …

Robust Rnai-Based Resistance To Mixed Infection Of Three Viruses In Soybean Plants Expressing Separate Short Hairpins From A Single Transgene, Xiuchun Zhang, Shirley Sato, Xiaohong Ye, Anne E. Dorrance, Thomas Jack Morris, Thomas E. Clemente, Feng Qu

Nebraska Center for Virology: Faculty Publications

Transgenic plants expressing double-stranded RNA (dsRNA) of virus

origin have been previously shown to confer resistance to virus infections

through the highly conserved RNA-targeting process termed RNA silencing

or RNA interference (RNAi). In this study we applied this strategy to

soybean plants and achieved robust resistance to multiple viruses with a

single dsRNA-expressing transgene. Unlike previous reports that relied

on the expression of one long inverted repeat (IR) combining sequences

of several viruses, our improved strategy utilized a transgene designed to

express several shorter IRs. Each of these short IRs contains highly conserved

sequences of one virus, forming dsRNA of …

Kaposi Sarcoma-Associated Herpesvirus Degrades Cellular Toll-Interleukin-1 Receptor Domain-Containing Adaptor-Inducing Β-Interferon (Trif), Humera Ahmad, Rachel Gubbels, Florencia Meyer, Thomas Waterbury, Rongtuan Lin, Luwen Zhang

Nebraska Center for Virology: Faculty Publications

Kaposi sarcoma-associated herpesvirus (KSHV) is a human ƴ - herpesvirus associated with several human malignancies. The replication and transcription activator (RTA) is necessary and sufficient for the switch from KSHV latency to lytic replication. Toll-interleukin-1 receptor (TIR) domain-containing adaptorinducing β-interferon (TRIF, also called TIR-domain-containing adaptor molecule-1 (TICAM-1)) is a signaling adaptor molecule that is critically involved in the Toll-like receptor 3 (TLR-3) and TLR-4 signaling pathways for type I interferon (IFN) production, a key component of innate immunity against microbial infection. In this report, we find a new mechanism by which RTA blocks innate immunity by targeting cellular TRIF. RTA …

Human Papillomavirus 16 Variants From Zambian Women With Normal Pap Smears, Yan Jun Lei, Kgomotso Makhaola, Daraporn Pittayakhajonwut, Charles Wood, Peter C. Angeletti

Nebraska Center for Virology: Faculty Publications

Human papillomavirus (HPV) type 16 is the most prevalent high-risk viral genotype associated with cervical cancer. Six distinct phylogenetic clusters of HPVs have been identified and are distributed differently across five continents. HPV16 DNA was extracted from cervico-lavage samples from women with normal pap smears. The LCR regions were amplified in triplicate, cloned, sequenced, and analyzed from a total of 11 recovered HPV16 positive samples [Ng’andwe et al. (2007): BMC Infect Dis 7:77] were analyzed for sequence variation. The HPV16 LCR variants were assessed for promoter activity by use of a luciferase reporter gene. Six novel HPV16 variants with nucleotide …

Hiv-1 Clade B And C Isolates Exhibit Differential Replication: Relevance To Macrophage-Mediated Neurotoxicity, Agnes A. Constantino, Yunlong Huang, Hong Zhang, Charles Wood, Jialin C. Zheng

Nebraska Center for Virology: Faculty Publications

HIV-associated neurocognitive disorders (HAND) continue to be a consequence of HIV-1 infection among clade B-infected individuals. In contrast, the incidence of severe neurological impairment is lower among clade C-infected patients in regions of Sub-Saharan Africa and India. Biological aspects such as replication, cytopathicity, inflammatory response, and neurotoxicity unique to each clade influence neuropathogenicity and ultimately affect the clinical outcome of the disease. We hypothesize that productive infection by clade C isolates leads to macrophagemediated neurotoxicity, although to a lesser extent than clade B isolates. Using a panel of primary isolates of clades B and C we demonstrated that clade B …

The Zambia Children's Ks-Hhv8 Study: Rationale, Study Design, And Study Methods, Veenu Minhas, Kay L. Crabtree, Ann Chao, Janet M. Wojcicki, Adrian M. Sifuniso, Catherine Nkonde, Chipepo Kankasa, Charles D. Mitchell, Charles Wood

Nebraska Center for Virology: Faculty Publications

The epidemic of human immunodeficiency virus in Zambia has led to a dramatic rise in the incidence of human herpesvirus-8 (HHV-8)–associated Kaposi's sarcoma in both adults and children. However, there is a paucity of knowledge about the routes of HHV-8 transmission to young children. The Zambia Children's KS-HHV8 Study, a large, prospective cohort study in Lusaka, Zambia, was launched in 2004 to investigate the role of household members as a source of HHV-8 infection in young children and social behaviors that may modify the risk of HHV-8 acquisition. This cohort is distinct from other epidemiologic studies designed to investigate HHV-8 …

Prevalence Of Human Herpesvirus 8 (Hhv8) And Hepatitis C Virus (Hcv) In A Rural Community With High Risk For Blood Borne Infections In Central China, Tiejun Zhang, Na He, Yingying Ding, Kay L. Crabtree, Veenu Minhas, Charles Wood

Nebraska Center for Virology: Faculty Publications

Former illegal blood donation in the past decade has caused HIV outbreaks in some rural areas in China. Other HIV associated virus infections, such as human herpesvirus 8 (HHV8) in such areas are still not well defined. In order to explore HHV8 and HCV seroprevalence and potential risk factors in such areas, a cross-sectional study with 305 HIV positive and 315 HIV negative subjects recruited from a rural county in Shanxi province was conducted, where illegal blood collection was reported. Interview questionnaires and serum testing were carried out with these participants. HCV and HHV8 seroprevalence were found to be higher …

Comparison Of Adenoviruses As Oncolytics And Cancer Vaccines In An Immunocompetent B Cell Lymphoma Model, Eric A. Weaver, Christopher Y. Chen, Shannon M. May, Mary E. Barry, Michael A. Barry

Nebraska Center for Virology: Faculty Publications

We have screened human adenoviruses (Ads) for oncolytic activity against a variety of mouse and hamster cell lines and have found a number that are susceptible to a variety of Ad serotypes. A20 lymphoma is derived from BALB/c mice and is susceptible to infection and killing by a variety of human Ads. A20 is also a suitable cancer vaccine model, because these cells express a unique immunoglobulin variable region that can be targeted by vaccination. To compare Ads as cancer vaccines versus Ads as oncolytics, A20 tumors were initiated in im- munocompetent BALB/c mice. Mice immunized with first-generation Ad5 expressing …

Advances And Future Challenges In Adenoviral Vector Pharmacology And Targeting, Reeti Khare, Christopher Y. Chen, Eric A. Weaver, Michael A. Barry

Nebraska Center for Virology: Faculty Publications

Adenovirus is a robust vector for therapeutic applications, but its use is limited by our understanding of its complex in vivo pharmacology. In this review we describe the necessity of identifying its natural, widespread, and multi-faceted interactions with the host since this information will be crucial for efficiently redirecting virus into target cells. In the rational design of vectors, the notion of overcoming a sequence of viral “sinks” must be combined with re-targeting to target populations with capsid as well as shielding the vectors from pre-existing or toxic immune responses. It must also be noted that most known adenoviral pharmacology …

Species D Adenoviruses As Oncolytics Against B-Cell Cancers, Christopher Y. Chen, Julien S. Senac, Eric A. Weaver, Shannon M. May, Diane F. Jelinek, Philip Greipp, Thomas Witzig, Michael A. Barry

Nebraska Center for Virology: Faculty Publications

Purpose: Oncolytic viruses are self-amplifying anticancer agents that make use of the natural ability of viruses to kill cells. Adenovirus serotype 5 (Ad5) has been extensively tested against solid cancers, but less so against B-cell cancers because these cells do not generally express the coxsackie and adenoviral receptor (CAR). To determine whether other adenoviruses might have better potency, we "mined" the adenovirus virome of 55 serotypes for viruses that could kill B-cell cancers.

Experimental Design: Fifteen adenoviruses selected to represent Ad species B, C, D, E, and F were tested in vitro against cell lines and primary patient B-cell cancers …

Regulation Of The Latency–Reactivation Cycle By Products Encoded By The Bovine Herpesvirus 1 (Bhv-1) Latency-Related Gene, Clinton Jones, Leticia Frizzo Da Silva, Devis Sinani

School of Veterinary and Biomedical Sciences: Faculty Publications

Like other α-herpesvirinae subfamily members, the primary site for bovine herpesvirus 1 (BHV-1) latency is ganglionic sensory neurons. Periodically BHV-1 reactivates from latency, virus is shed, and consequently virus transmission occurs. Transcription from the latency-related (LR) gene is readily detected in neurons of trigeminal ganglia (TG) of calves or rabbits latently infected with BHV-1. Two micro-RNAs and a transcript encompassing a small open reading frame (ORF-E) located within the LR promoter can also be detected in TG of latently infected calves. A BHV-1 mutant that contains stop codons near the beginning of the first open reading frame (ORF2) within the …

Campylobacter Ureolyticus: An Emerging Gastrointestinal Pathogen?, Susan Bullman, Daniel Corcoran, James O'Leary, Brigid Lucey, Deirdre Byrne, Roy D. Sleator

Department of Biological Sciences Publications

A total of 7194 faecal samples collected over a 1-year period from patients presenting with diarrhoea were screened for Campylobacter spp. using EntericBios, a multiplex-PCR system. Of 349 Campylobacter-positive samples, 23.8% were shown to be Campylobacter ureolyticus, using a combination of 16S rRNA gene analysis and highly specific primers targeting the HSP60 gene of this organism. This is, to the best of our knowledge, the first report of C. ureolyticus in the faeces of patients presenting with gastroenteritis and may suggest a role for this organism as an emerging enteric pathogen.

Analysis Of The Clear Plaque Phenotype Of The Bacteriophage Hk75, Phani Chandrika Kunapuli

Masters Theses & Specialist Projects

The growth of bacteriophage HK75 is inhibited by specific mutations in the zinc binding domain of the host RNA polymerase beta prime subunit. It shares this rare property with bacteriophage HK022 and other phages that use RNA mediated antitermination to promote early gene expression. Recent genomic analysis of HK75 and HK022 has confirmed the relatedness of these two phages and place HK75 in the lambdoid family of bacteriophages. Lambdoid phages are temperate and can adopt a lytic or lysogenic lifestyle upon infection of a suitable host. However, HK75 only forms clear plaques and thus appears to be defective in its …

Transcriptional Regulation Of Shigella Virulence Plasmid-Encoded Genes By Virb And Crp, Christopher Thomas Hensley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shigella flexneri is a species of Gram-negative intracellular pathogens that causes bacillary dysentery in humans. Shigella relies on the precise transcriptional regulation of virulence genes, encoded by a large virulence plasmid, for invasion and infection of human colonic epithelial cells. The transcription of most identified virulence genes are regulated through a cascade controlled by the primary regulator of virulence genes, VirF, and the global transcriptional regulator, VirB. Currently, few studies have addressed how individual Shigella virulence genes are precisely regulated for optimal expression during specific stages of pathogenesis and within the constraints of the regulatory cascade. This work addresses how …

Characterization Of The Agrobacterium Tumefaciens Virb2 Pilin Of The Virb/D4 Type Iv Secretion System, Jennifer Kerr

Dissertations and Theses (Open Access)

The Agrobacterium tumefaciens VirB/D4 type IV secretion system (T4SS) delivers oncogenic T-DNA and effector proteins to susceptible plant cells. This leads to the formation of tumors termed Crown Galls. The VirB/D4 T4SS is comprised of 12 subunits (VirB1 to VirB11 and VirD4), which assemble to form two structures, a secretion channel spanning the cell envelope and a T-pilus extending from the cell surface. In A. tumefaciens, the VirB2 pilin subunit is required for assembly of the secretion channel and is the main subunit of the T-pilus. The focus of this thesis is to define key reactions associated with the T4SS …

Agrobacterium Virb10 Contributions To Type Iv Substrate Secretion, T-Pilus Biogenesis, And Outer Membrane Pore Formation, Isaac Garza

Dissertations and Theses (Open Access)

The VirB/D4 type IV secretion system (T4SS) of Agrobacterium tumefaciens functions to transfer substrates to infected plant cells through assembly of a translocation channel and a surface structure termed a T-pilus. This thesis is focused on identifying contributions of VirB10 to substrate transfer and T-pilus formation through a mutational analysis. VirB10 is a bitopic protein with several domains, including a: (i) cytoplasmic N-terminus, (ii) single transmembrane (TM) α-helix, (iii) proline-rich region (PRR), and (iv) large C-terminal modified β-barrel. I introduced cysteine insertion and substitution mutations throughout the length of VirB10 in order to: (i) test a predicted transmembrane topology, (ii) …

Dorsal Eye Selector Pannier (Pnr) Suppresses The Eye Fate To Define Dorsal Margin Of The Drosophila Eye, Sarah M. Oros, Meghana Tare, Madhuri Kango-Singh, Amit Singh

Biology Faculty Publications

Axial patterning is crucial for organogenesis. During Drosophila eye development, dorso-ventral (DV) axis determination is the first lineage restriction event. The eye primordium begins with a default ventral fate, on which the dorsal eye fate is established by expression of the GATA-1 transcription factor pannier (pnr). Earlier, it was suggested that loss of pnr function induces enlargement in the dorsal eye due to ectopic equator formation. Interestingly, we found that in addition to regulating DV patterning, pnr suppresses the eye fate by downregulating the core retinal determination genes eyes absent (eya), sine oculis (so) and dacshund (dac) to define the …

The Armadillo Repeat Protein Pf16 Is Essential For Flagellar Structure And Function In Plasmodium Male Gametes, Ursula Straschil, Arthur M. Talman, David J. P. Ferguson, Karen A. Bunting, Zhengyao Xu, Elizabeth Bailes, Robert E. Sinden, Anthony A. Holder, Elizabeth F. Smith

Dartmouth Scholarship

Malaria, caused by the apicomplexan parasite Plasmodium, threatens 40% of the world's population. Transmission between vertebrate and insect hosts depends on the sexual stages of the life-cycle. The male gamete of Plasmodium parasite is the only developmental stage that possesses a flagellum. Very little is known about the identity or function of proteins in the parasite's flagellar biology. Here, we characterise a Plasmodium PF16 homologue using reverse genetics in the mouse malaria parasite Plasmodium berghei. PF16 is a conserved Armadillo-repeat protein that regulates flagellar structure and motility in organisms as diverse as green algae and mice. We show that …

Conidia But Not Yeast Cells Of The Fungal Pathogen Histoplasma Capsulatum Trigger A Type I Interferon Innate Immune Response In Murine Macrophages, Diane O. Inglis, Charlotte A. Berkes, Davina R. Hocking Murray, Anita Sil

Biology Faculty Publications

Histoplasma capsulatum is the most common cause of fungal respiratory infections and can lead to progressive disseminated infections, particularly in immunocompromised patients. Infection occurs upon inhalation of the aerosolized spores, known as conidia. Once inside the host, conidia are phagocytosed by alveolar macrophages. The conidia subsequently germinate and produce a budding yeast-like form that colonizes host macrophages and can disseminate throughout host organs and tissues. Even though conidia are the predominant infectious particle for H. capsulatum and are the first cell type encountered by the host during infection, very little is known at a molecular level about conidia or about …

Splice Factor Sfrs6: Regulation By P53 And Effect On Il-24 Splicing, Erin L. Schmidt

Loma Linda University Electronic Theses, Dissertations & Projects

Alternative splicing of RNA transcripts is emerging as a major mechanism for expanding the proteome. Splice pattern changes are found in numerous diseases and cancers, indicating the importance of tight control over this process. While the mechanism of splicing has been described in detail, it is less clear how a cell is able to modify its splicing patterns in response to different conditions. Our lab previously demonstrated that DNA damage can induce SFRS6, the gene coding for splicing factor SRp55, thereby leading to changes in the splicing patterns of several target genes related to survival and apoptosis. We also …

Genome Sequence Of The Model Mushroom Schizophyllum Commune, Robin A. Ohm, Jan F. De Jong, Luis G. Lugones, Andrea Aerts, Erika Kothe, Jason E. Stajich, Ronald P. De Vries, Eric Record, Anthony Levasseur, Scott E. Baker, Kirk A. Bartholomew, Pedro M. Coutinho, Susann Erdmann, Thomas J. Fowler, Allen C. Gathmen, Vincent Lombard, Bernard Henrissat, Nicole Knabe, Ursula Kues, Walt W. Lily

Biology Faculty Publications

Much remains to be learned about the biology of mushroom-forming fungi, which are an important source of food, secondary metabolites and industrial enzymes. The wood-degrading fungus Schizophyllum commune is both a genetically tractable model for studying mushroom development and a likely source of enzymes capable of efficient degradation of lignocellulosic biomass. Comparative analyses of its 38.5-megabase genome, which encodes 13,210 predicted genes, reveal the species's unique wood-degrading machinery. One-third of the 471 genes predicted to encode transcription factors are differentially expressed during sexual development of S. commune. Whereas inactivation of one of these, fst4, prevented mushroom formation, inactivation of another, …

Development Of Pyrf-Based Genetic System For Targeted Gene Deletion In Clostridium Thermocellum And Creation Of A Pta Mutant, Shital A. Tripathi, Daniel G. Olson, D. Aaron Argyros, Bethany B. Miller, Trisha F. Barrett, Daniel M. Murphy, Jesse D. Mccool, Anne K. Warner, Vineet B. Rajgarhia, Lee R. Lynd, David A. Hogsett, Nicky C. Caiazza

Dartmouth Scholarship

We report development of a genetic system for making targeted gene knockouts in Clostridium thermocellum, a thermophilic anaerobic bacterium that rapidly solubilizes cellulose. A toxic uracil analog, 5-fluoroorotic acid (5-FOA), was used to select for deletion of the pyrF gene. The ΔpyrF strain is a uracil auxotroph that could be restored to a prototroph via ectopic expression of pyrF from a plasmid, providing a positive genetic selection. Furthermore, 5-FOA was used to select against plasmid-expressed pyrF, creating a negative selection for plasmid loss. This technology was used to delete a gene involved in organic acid production, namely pta, which encodes …

The Small Regulatory Rna Ryhb Regulates Icsa Expression In Shigella Flexneri, Nick Egan, Helen J. Wing

Undergraduate Research Opportunities Program (UROP)

Shigella flexneri is a gram negative non-motile, non-spore forming, rod-shaped bacterium responsible for bacillary dysentery in humans. The master regulator, VirF, initiates a cascade of virulence gene activation by acting as a transcription factor for the gene encoding the global regulator, VirB (1). Production of VirB is also negatively regulated by the regulatory small RNA (sRNA), RyhB 2). Regulatory sRNAs are untranslated RNA molecules involved in the regulation of both transcription and translation. RyhB, a 90 nt sRNA, was first identified in E. coli and subsequently found in all Shigella species. In Shigella this sRNA is maximally expressed in response …

Antibiotic Resistance In Bacillus Subtilis As Affected By Transcriptional Derepression And The Stringent Response, Brandon Eisinger, Ronald E. Yasbin, Eduardo A. Robleto

Undergraduate Research Opportunities Program (UROP)

Bacterial cells under conditions of starvation or prolonged non-lethal selective pressures accumulate mutations in highly transcribed genes. This process is part of cellular programs to increase genetic diversity in conditions of stress, also known as stationary phase or stress-induced mutagenesis. This experiment investigated mutation frequencies for antibiotic resistance as affected by the stringent response. The stringent response is a global cellular process that initiates at the cessation of growth and mediates changes in gene expression that repress synthesis of ribosome components. We used Bacillus subtilis strains that differ in RelA proficiency. The relA gene controls the synthesis of (p)ppGpp, the …