scholarly journals Evaluation of glove type on survival and transfer of Escherichia coli in model systems and during hand harvesting of lettuce

JSFA reports ◽  
2021 ◽  
Author(s):  
Irene Y. Zhao ◽  
Jiin Jung ◽  
Anne‐laure Moyne ◽  
Donald W. Schaffner ◽  
Linda J. Harris
Keyword(s):  
Escherichia Coli ◽  
Model Systems

scholarly journals A spectrophotometric study of the secondary structure of ribonucleic acid isolated from the smaller and larger ribosomal subparticles of rabbit reticulocytes

1970 ◽  
Vol 117 (1) ◽  
pp. 101-118 ◽  
Author(s):  
R. A. Cox
Keyword(s):  
Escherichia Coli ◽  
Ionic Strength ◽  
Secondary Structure ◽  
Ribonucleic Acid ◽  
Spectrophotometric Study ◽  
Urea Concentration ◽  
Model Systems ◽  
Base Pairs ◽  
Virus Like Particles ◽  
Rabbit Reticulocytes

The spectrum of RNA from the smaller and larger subparticles of rabbit reticulocyte ribosomes was studied as a function of pH, ionic strength, urea concentration and temperature. It was inferred that both RNA species form short double-helical segments of not more than about 10 base-pairs in length. Not more than about 70% of the base residues may be located in double-helical segments. RNA from the larger subparticle is richer in guanine and cytosine residues and its secondary structure is the more stable. These conclusions are based on the use of double-helical RNA from virus-like particles and of unfractionated Escherichia coli tRNA as model systems.

scholarly journals Preface

1995 ◽  
Vol 347 (1319) ◽  
pp. 3-3
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Molecular Mechanisms ◽  
Model Systems ◽  
Biochemical Pathways ◽  
Major Threat ◽  
Environmental Agents ◽  
Living Organisms ◽  
New Research ◽  
Micro Organisms

Genomic instability is a major threat to living organisms. To counteract the damaging effects posed by endogenous and environmental agents, such as chemicals or radiation, micro-organisms devote several percent of their genome to encode proteins that function in the repair and recombination of DNA. For many years, a relatively small group of scientists have carefully delineated the molecular mechanisms of these repair processes, using the simplest model systems available, namely Escherichia coli and Saccharomyces cerevisiae . These studies, which until recently had only moderate impact outside of the field, now provide the cornerstone for exciting new research into analogous processes in hum an cells. The reason for this is the revelation that the biochemical pathways for the accurate replication, repair and recombination of DNA have been conserved through evolution.

scholarly journals Escherichia coli has a Unique Transcriptional Program in Long-Term Stationary Phase

2020 ◽  
Author(s):  
Karin E. Kram ◽  
Autumn Henderson ◽  
Steven E. Finkel
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Experimental Evolution ◽  
Model Systems ◽  
Natural Environments ◽  
Complex Environments ◽  
Transcriptional Program ◽  
Complex Environment ◽  
Stressful Environment

AbstractMicrobes live in complex and consistently changing environments, but it is difficult to replicate this in the laboratory. Escherichia coli has been used as a model organism in experimental evolution studies for years; specifically, we and others have used it to study evolution in complex environments by incubating the cells into long-term stationary phase (LTSP) in rich media. In LTSP, cells experience a variety of stresses and changing conditions. While we have hypothesized that this experimental system is more similar to natural environments than some other lab conditions, we do not yet know how cells respond to this environment biochemically or physiologically. In this study, we begin to unravel the cells’ responses to this environment by characterizing the transcriptome of cells during LTSP. We found that cells in LTSP have a unique transcriptional program, and that several genes are uniquely upregulated or downregulated in this phase. Further, we identified two genes, cspB and cspI, which are most highly expressed in LTSP, even though these genes are primarily known to respond to cold-shock. When competed with wild-type cells, these genes are also important for survival during LTSP. These data allow us to compare biochemical responses to multiple environments and identify useful model systems, identify gene products that may play a role in survival in this complex environment, and identify novel functions of proteins.ImportanceExperimental evolution studies have elucidated evolutionary processes, but usually in chemically well-defined and/or constant environments. Using complex environments is important to begin to understand how evolution may occur in natural environments, such as soils or within a host. However, characterizing the stresses cells experience in these complex environments can be challenging. One way to approach this is by determining how cells biochemically acclimate to heterogenous environments. In this study we begin to characterize physiological changes by analyzing the transcriptome of cells in a dynamic complex environment. By characterizing the transcriptional profile of cells in long-term stationary phase, a heterogenous and stressful environment, we can begin to understand how cells physiologically and biochemically react to the laboratory environment, and how this compares to more natural conditions.

Pulsed UV-Light Penetration of Characterization and the Inactivation of Escherichia coli K12 in Solid Model Systems

2008 ◽  
Vol 51 (1) ◽  
pp. 195-204 ◽  
Author(s):  
K. L. Bialka ◽  
A. Demirci ◽  
P. N. Walker ◽  
V. M. Puri
Keyword(s):  
Escherichia Coli ◽  
Uv Light ◽  
Model Systems ◽  
Solid Model ◽  
Light Penetration ◽  
Escherichia Coli K12 ◽  
Pulsed Uv Light

Effects of Water Activity in Model Systems on High-Pressure Inactivation of Escherichia coli

2008 ◽  
Vol 2 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Ilona Setikaite ◽  
Tatiana Koutchma ◽  
Eduardo Patazca ◽  
Brian Parisi
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Water Activity ◽  
Model Systems

scholarly journals Role of Type 1 Fimbria- and P Fimbria-Specific Adherence in Colonization of the Neurogenic Human Bladder by Escherichia coli

2002 ◽  
Vol 70 (11) ◽  
pp. 6481-6484 ◽  
Author(s):  
Richard A. Hull ◽  
William H. Donovan ◽  
Michael Del Terzo ◽  
Colleen Stewart ◽  
Margaret Rogers ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Asymptomatic Bacteriuria ◽  
Model Systems ◽  
Human Beings ◽  
Human Bladder ◽  
E Coli

ABSTRACT Recent clinical studies suggest that the deliberate colonization of the human bladder with a prototypic asymptomatic bacteriuria-associated bacterium, Escherichia coli 83972, may reduce the frequency of urinary tract infection in individuals with spinal cord injuries. However, the mechanism by which E. coli 83972 colonizes the bladder is unknown. We examined the role in bladder colonization of the E. coli 83972 genes papG and fimH, which respectively encode P and type 1 receptor-specific fimbrial adhesins. E. coli 83972 and isogenic papGΔ and papGΔ fimHΔ mutants of E. coli 83972 were compared for their capacities to colonize the neurogenic human bladder. Both strains were capable of stable colonization of the bladder. The results indicated that type 1 class-specific adherence and P class-specific adherence, while implicated as significant colonization factors in experiments that employed various animal model systems, were not required for colonization of the neurogenic bladder in human beings. The implications of these results with regard to the selection of potential vaccine antigens for the prevention of urinary tract infection are discussed.

scholarly journals Systematic exploration of Escherichia coli phage–host interactions with the BASEL phage collection

PLoS Biology ◽  
2021 ◽  
Vol 19 (11) ◽  
pp. e3001424
Author(s):  
Enea Maffei ◽  
Aisylu Shaidullina ◽  
Marco Burkolter ◽  
Yannik Heyer ◽  
Fabienne Estermann ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacterial Infections ◽  
Molecular Mechanisms ◽  
Model Systems ◽  
Host Recognition ◽  
Ecological Niches ◽  
Traditional Model ◽  
Host Interactions ◽  
Trade Offs ◽  
Systematic Exploration

Bacteriophages, the viruses infecting bacteria, hold great potential for the treatment of multidrug-resistant bacterial infections and other applications due to their unparalleled diversity and recent breakthroughs in their genetic engineering. However, fundamental knowledge of the molecular mechanisms underlying phage–host interactions is mostly confined to a few traditional model systems and did not keep pace with the recent massive expansion of the field. The true potential of molecular biology encoded by these viruses has therefore remained largely untapped, and phages for therapy or other applications are often still selected empirically. We therefore sought to promote a systematic exploration of phage–host interactions by composing a well-assorted library of 68 newly isolated phages infecting the model organism Escherichia coli that we share with the community as the BASEL (BActeriophage SElection for your Laboratory) collection. This collection is largely representative of natural E. coli phage diversity and was intensively characterized phenotypically and genomically alongside 10 well-studied traditional model phages. We experimentally determined essential host receptors of all phages, quantified their sensitivity to 11 defense systems across different layers of bacterial immunity, and matched these results to the phages’ host range across a panel of pathogenic enterobacterial strains. Clear patterns in the distribution of phage phenotypes and genomic features highlighted systematic differences in the potency of different immunity systems and suggested the molecular basis of receptor specificity in several phage groups. Our results also indicate strong trade-offs between fitness traits like broad host recognition and resistance to bacterial immunity that might drive the divergent adaptation of different phage groups to specific ecological niches. We envision that the BASEL collection will inspire future work exploring the biology of bacteriophages and their hosts by facilitating the discovery of underlying molecular mechanisms as the basis for an effective translation into biotechnology or therapeutic applications.

scholarly journals Biosynthesis of the Polymannose Lipopolysaccharide O-antigens from Escherichia coli Serotypes O8 and O9a Requires a Unique Combination of Single- and Multiple-active Site Mannosyltransferases

2012 ◽  
Vol 287 (42) ◽  
pp. 35078-35091 ◽  
Author(s):  
Laura K. Greenfield ◽  
Michele R. Richards ◽  
Jianjun Li ◽  
Warren W. Wakarchuk ◽  
Todd L. Lowary ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Active Sites ◽  
Repeat Unit ◽  
Model Systems ◽  
Glycan Structure ◽  
Repeat Units ◽  
Mutant Complementation ◽  
O Antigens

The Escherichia coli O9a and O8 O-antigen serotypes represent model systems for the ABC transporter-dependent synthesis of bacterial polysaccharides. The O9a and O8 antigens are linear mannose homopolymers containing conserved reducing termini (the primer-adaptor), a serotype-specific repeat unit domain, and a terminator. Synthesis of these glycans occurs on the polyisoprenoid lipid-linked primer, undecaprenol pyrophosphoryl-GlcpNAc, by two conserved mannosyltransferases, WbdC and WbdB, and a serotype-specific mannosyltransferase, WbdA. The glycan structure and pattern of conservation in the O9a and O8 mannosyltransferases are not consistent with the existing model of O9a biosynthesis. Here we establish a revised pathway using a combination of in vivo (mutant complementation) experiments and in vitro strategies with purified enzymes and synthetic acceptors. WbdC and WbdB synthesize the adaptor region, where they transfer one and two α-(1→3)-linked mannose residues, respectively. The WbdA enzymes are solely responsible for forming the repeat unit domains of these O-antigens. WbdAO9a has two predicted active sites and polymerizes a tetrasaccharide repeat unit containing two α-(1→3)- and two α-(1→2)-linked mannopyranose residues. In contrast, WbdAO8 polymerizes trisaccharide repeat units containing single α-(1→3)-, α-(1→2)-, and β-(1→2)-mannopyranoses. These studies illustrate assembly systems exploiting several mannosyltransferases with flexible active sites, arranged in single- and multiple-domain formats.

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