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Full-Text Articles in Life Sciences
Regulation Of The Escherichia Coli Hipba Toxin-Antitoxin System By Proteolysis, Sonja Hansen, Marin Vulić, Tien-Jui Yen, Maria A. Schumacher, Richard G. Brennan, Kim Lewis
Regulation Of The Escherichia Coli Hipba Toxin-Antitoxin System By Proteolysis, Sonja Hansen, Marin Vulić, Tien-Jui Yen, Maria A. Schumacher, Richard G. Brennan, Kim Lewis
Marin Vulić
Bacterial populations produce antibiotic-tolerant persister cells. A number of recent studies point to the involvement of toxin/antitoxin (TA) modules in persister formation. hipBA is a type II TA module that codes for the HipB antitoxin and the HipA toxin. HipA is an EF-Tu kinase, which causes protein synthesis inhibition and dormancy upon phosphorylation of its substrate. Antitoxins are labile proteins that are degraded by one of the cytosolic ATP-dependent proteases. We followed the rate of HipB degradation in different protease deficient strains and found that HipB was stabilized in a lon- background. These findings were confirmed in an in vitro …
Bacterial Community Profiling Of The Eastern Oyster (Crassostrea Virginica): Comparison Of Culture-Dependent And Culture-Independent Outcomes, Kenneth J. La Valley, Steve Jones, Marta Gomez-Chiarri, Joseph Dealteris, Michael A. Rice
Bacterial Community Profiling Of The Eastern Oyster (Crassostrea Virginica): Comparison Of Culture-Dependent And Culture-Independent Outcomes, Kenneth J. La Valley, Steve Jones, Marta Gomez-Chiarri, Joseph Dealteris, Michael A. Rice
Michael A Rice
Tissue-associated bacterial community profiles generated using a nested polymerase chain reaction–denaturing gradient gel electrophoresis (DGGE) approach and culture-dependent and culture-independent isolation techniques were compared. Oyster samples were collected from 2 harvest areas along the coast of Maine, in the United States. Profiles from both isolation strategies were evaluated using Sorensen’s index of similarity and cluster analysis of gel banding patterns. Cultureindependent profiles were further evaluated using the Shannon diversity index. In general, the culture-dependent strategy resulted in a greater number of bands within a profile. BacterialDGGEprofiles were found to be highly similar within an isolation strategy, with a higher degree …
Recombinant Expression Of Indolicidin Concatemers In Escherichia Coli, K Morin, S Arcidiacono, Richard Beckwitt, C Mello
Recombinant Expression Of Indolicidin Concatemers In Escherichia Coli, K Morin, S Arcidiacono, Richard Beckwitt, C Mello
Richard D Beckwitt
Antimicrobial peptides are part of the innate immune system of vertebrates and invertebrates. They are active against gram-negative and gram-positive bacteria, fungi, and protozoa. Currently, most antimicrobial peptides are extracted from host organisms or produced by solidphase peptide synthesis. Recombinant protein expression in Escherichia coli is a tool for greater production yields at a decreased cost and reduces the use of hazardous materials. We have constructed a concatamer of indolicidin and successfully expressed a fusion product with thioredoxin in E. coli BL21DE3. Codons for methionine residues flanking individual indolicidin genes were incorporated for cyanogen bromide cleavage of the fusion protein …
Regulation Of The Escherichia Coli Hipba Toxin-Antitoxin System By Proteolysis, Sonja Hansen, Marin Vulić, Tien-Jui Yen, Maria A. Schumacher, Richard G. Brennan, Kim Lewis
Regulation Of The Escherichia Coli Hipba Toxin-Antitoxin System By Proteolysis, Sonja Hansen, Marin Vulić, Tien-Jui Yen, Maria A. Schumacher, Richard G. Brennan, Kim Lewis
Kim Lewis
Bacterial populations produce antibiotic-tolerant persister cells. A number of recent studies point to the involvement of toxin/antitoxin (TA) modules in persister formation. hipBA is a type II TA module that codes for the HipB antitoxin and the HipA toxin. HipA is an EF-Tu kinase, which causes protein synthesis inhibition and dormancy upon phosphorylation of its substrate. Antitoxins are labile proteins that are degraded by one of the cytosolic ATP-dependent proteases. We followed the rate of HipB degradation in different protease deficient strains and found that HipB was stabilized in a lon- background. These findings were confirmed in an in vitro …
Enumeration Of Sandy Sediment Bacteria: Search For Optimal Protocol, Slava Epstein, Jeffrey Rossel
Enumeration Of Sandy Sediment Bacteria: Search For Optimal Protocol, Slava Epstein, Jeffrey Rossel
Slava Epstein
We examined and compared a variety of existing protocols for enumeration of bacteria from marine sandy sediments. The focus was on how to dislodge bacteria from sediment particles; a commercial blender, an ultrasonic cleaner, and an ultrasonic cell disrupter were tested. The ultrasonic cell disrupter was found to be the most efficient device for bacterial dislodgment. With a 5 mm microtip vibrating at 109 μm amplitude and 20 kHz, the optimal sonication time of small (≤ 0.5 cm³) samples was 180 s. Having identified the optimal dislodgment treatment, we went through other steps of sediment bacteria enumeration (use of surfactants, …
Enumeration Of Sandy Sediment Bacteria: Are The Counts Quantitative Or Relative?, Slava S. Epstein, D. Alexander, K. Cosman, A. Dompé, S. Gallagher, J. Jarsobski, E. Laning, R. Martinez, G. Panasik, C. Peluso, R. Runde, E. Timmer
Enumeration Of Sandy Sediment Bacteria: Are The Counts Quantitative Or Relative?, Slava S. Epstein, D. Alexander, K. Cosman, A. Dompé, S. Gallagher, J. Jarsobski, E. Laning, R. Martinez, G. Panasik, C. Peluso, R. Runde, E. Timmer
Slava Epstein
Several tests were carried out to enable evaluation of the precision with which sandy sediment bacteria could be enumerated. This represented the first attempt to place direct epifluorescence counts of benthic bacteria on a quantitative, rather than relative, ground. The tests combined in situ radioisotope ([³H], [¹⁴C]) labeling of sediment bacteria, bacterial dislodgment by ultrasonic treatment, and bacterial enumeration via fluorescent staining. The results provided direct and indirect evidence that the employed protocol for bacterial enumeration accounted for 88 to 98% of all bacteria present in sediments. The identified approach thus allowed for a rather complete quantification of sediment bacteria. …
Ciprofloxacin Causes Persister Formation By Inducing The Tisb Toxin In Escherichia Coli, Tobias Dörr, Marin Vulić, Kim Lewis
Ciprofloxacin Causes Persister Formation By Inducing The Tisb Toxin In Escherichia Coli, Tobias Dörr, Marin Vulić, Kim Lewis
Marin Vulić
Bacteria induce stress responses that protect the cell from lethal factors such as DNA-damaging agents. Bacterial populations also form persisters, dormant cells that are highly tolerant to antibiotics and play an important role in recalcitrance of biofilm infections. Stress response and dormancy appear to represent alternative strategies of cell survival. The mechanism of persister formation is unknown, but isolated persisters show increased levels of toxin/antitoxin (TA) transcripts. We have found previously that one or more components of the SOS response induce persister formation after exposure to a DNA-damaging antibiotic. The SOS response induces several TA genes in Escherichia coli. Here, …
Sos Response Induces Persistence To Fluoroquinolones In Escherichia Coli, Tobias Dörr, Kim Lewis, Marin Vulić
Sos Response Induces Persistence To Fluoroquinolones In Escherichia Coli, Tobias Dörr, Kim Lewis, Marin Vulić
Marin Vulić
Bacteria can survive antibiotic treatment without acquiring heritable antibiotic resistance. We investigated persistence to the fluoroquinolone ciprofloxacin in Escherichia coli. Our data show that a majority of persisters to ciprofloxacin were formed upon exposure to the antibiotic, in a manner dependent on the SOS gene network. These findings reveal an active and inducible mechanism of persister formation mediated by the SOS response, challenging the prevailing view that persisters are pre-existing and formed purely by stochastic means. SOS-induced persistence is a novel mechanism by which cells can counteract DNA damage and promote survival to fluoroquinolones. This unique survival mechanism may be …
Ciprofloxacin Causes Persister Formation By Inducing The Tisb Toxin In Escherichia Coli, Tobias Dörr, Marin Vulić, Kim Lewis
Ciprofloxacin Causes Persister Formation By Inducing The Tisb Toxin In Escherichia Coli, Tobias Dörr, Marin Vulić, Kim Lewis
Kim Lewis
Bacteria induce stress responses that protect the cell from lethal factors such as DNA-damaging agents. Bacterial populations also form persisters, dormant cells that are highly tolerant to antibiotics and play an important role in recalcitrance of biofilm infections. Stress response and dormancy appear to represent alternative strategies of cell survival. The mechanism of persister formation is unknown, but isolated persisters show increased levels of toxin/antitoxin (TA) transcripts. We have found previously that one or more components of the SOS response induce persister formation after exposure to a DNA-damaging antibiotic. The SOS response induces several TA genes in Escherichia coli. Here, …
Persisters: A Distinct Physiological State Of E. Coli, Devang Shah, Zhigang Zhang, Arkady B. Khodursky, Niilo Kaldalu, Kristi Kurg, Kim Lewis
Persisters: A Distinct Physiological State Of E. Coli, Devang Shah, Zhigang Zhang, Arkady B. Khodursky, Niilo Kaldalu, Kristi Kurg, Kim Lewis
Kim Lewis
BackgroundBacterial populations contain persisters, phenotypic variants that constitute approximately 1% of cells in stationary phase and biofilm cultures. Multidrug tolerance of persisters is largely responsible for the inability of antibiotics to completely eradicate infections. Recent progress in understanding persisters is encouraging, but the main obstacle in understanding their nature was our inability to isolate these elusive cells from a wild-type population since their discovery in 1944. ResultsWe hypothesized that persisters are dormant cells with a low level of translation, and used this to physically sort dim E. coli cells which do not contain sufficient amounts of unstable GFP expressed from …
Sos Response Induces Persistence To Fluoroquinolones In Escherichia Coli, Tobias Dörr, Kim Lewis, Marin Vulić
Sos Response Induces Persistence To Fluoroquinolones In Escherichia Coli, Tobias Dörr, Kim Lewis, Marin Vulić
Kim Lewis
Bacteria can survive antibiotic treatment without acquiring heritable antibiotic resistance. We investigated persistence to the fluoroquinolone ciprofloxacin in Escherichia coli. Our data show that a majority of persisters to ciprofloxacin were formed upon exposure to the antibiotic, in a manner dependent on the SOS gene network. These findings reveal an active and inducible mechanism of persister formation mediated by the SOS response, challenging the prevailing view that persisters are pre-existing and formed purely by stochastic means. SOS-induced persistence is a novel mechanism by which cells can counteract DNA damage and promote survival to fluoroquinolones. This unique survival mechanism may be …
Communities Of Cloacal Bacteria In Tree Swallow Families, Michael Lombardo, Patrick Thorpe, R. Cichewicz, M. Henshaw, C. Millard, C. Steen, T. Zeller
Communities Of Cloacal Bacteria In Tree Swallow Families, Michael Lombardo, Patrick Thorpe, R. Cichewicz, M. Henshaw, C. Millard, C. Steen, T. Zeller
Michael P Lombardo
Our aim in this study was to survey the communities of bacteria found in the cloacae of adult and nestling Tree Swallows (Tachycineta bicolor), determine if there were familial patterns of prevalence, and determine if there were relationships between bacteria loads and nestling size when 12 days old and fledging success.