An Approximative Approach for Single Cell Spatial Modeling of Quorum Sensing

2015 ◽  
Vol 22 (3) ◽  
pp. 227-235 ◽  
Author(s):  
Meltem Gölgeli Matur ◽  
Johannes Müller ◽  
Christina Kuttler ◽  
Burkhard A. Hense
Keyword(s):  
Quorum Sensing ◽  
Single Cell ◽  
Spatial Modeling ◽  
Approximative Approach

scholarly journals Intra-Species Bacterial Quorum Sensing Studied at Single Cell Level in a Double Droplet Trapping System

2013 ◽  
Vol 14 (5) ◽  
pp. 10570-10581 ◽  
Author(s):  
Yunpeng Bai ◽  
Santoshkumar Patil ◽  
Steven Bowden ◽  
Simon Poulter ◽  
Jie Pan ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Single Cell ◽  
Single Cell Level ◽  
Cell Level ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum ◽  
Droplet Trapping

scholarly journals Escherichia coli Quorum-Sensing EDF, A Peptide Generated by Novel Multiple Distinct Mechanisms and Regulated by trans -Translation

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Sathish Kumar ◽  
Ilana Kolodkin-Gal ◽  
Oliver Vesper ◽  
Nawsad Alam ◽  
Ora Schueler-Furman ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Single Cell ◽  
Molecular Mechanisms ◽  
Regulatory System ◽  
Stress Conditions ◽  
Translation System ◽  
Signal Molecules ◽  
Low Levels ◽  
Exit Tunnel ◽  
Density Dependency

ABSTRACT Eshcerichia coli mazEF is a stress-induced toxin-antitoxin module mediating cell death and requiring a quorum-sensing (QS) e xtracellular d eath f actor (EDF), the pentapeptide NNWNN. Here we uncovered several distinct molecular mechanisms involved in its generation from the zwf mRNA encoding glucose-6-phosphate dehydrogenase. In particular, we show that, under stress conditions, the endoribonuclease MazF cleaves specific ACA sites, thereby generating a leaderless zwf mRNA which is truncated 30 codons after the EDF-encoding region. Since the nascent ribosome peptide exit tunnel can accommodate up to 40 amino acids, this arrangement allows the localization of the EDF residues inside the tunnel when the ribosome is stalled at the truncation site. Moreover, ribosome stalling activates the trans -translation system, which provides a means for the involvement of ClpPX in EDF generation. Furthermore, the trans -translation is described as a regulatory system that attenuated the generation of EDF, leading to low levels of EDF in the single cell. Therefore, the threshold EDF molecule concentration required is achieved only by the whole population, as expected for QS. IMPORTANCE Bacteria communicate with one another via quorum-sensing (QS) signal molecules. QS provides a mechanism for bacteria to monitor each other’s presence and to modulate gene expression in response to population density. Previously, we added E. coli pentapeptide EDF to this list of QS molecules. We showed that, under stress conditions, the induced MazF, an endoribonuclease cleaving at ACA sites, generates EDF from zwf. Here we studied the mechanism of EDF generation and asked whether it is related to EDF density dependency. We illustrated that, under stress conditions, multiple distinct complex mechanisms are involved in EDF generation. This includes formation of leaderless truncated zwf mRNA by MazF, configuration of a length corresponding to the nascent ribosome peptide exit tunnel, rescue performed by the trans -translation system, and cleavage by ClpPX protease. trans -Translation is described as a regulatory system attenuating EDF generation and leading to low levels of EDF in the single cell, as expected for QS.

scholarly journals Quantifying the Integration of Quorum-Sensing Signals with Single-Cell Resolution

PLoS Biology ◽  
2009 ◽  
Vol 7 (3) ◽  
pp. e1000068 ◽  
Author(s):  
Tao Long ◽  
Kimberly C Tu ◽  
Yufang Wang ◽  
Pankaj Mehta ◽  
N. P Ong ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Single Cell ◽  
Quorum Sensing Signals

scholarly journals The Phosphorylation Flow of the Vibrio harveyi Quorum-Sensing Cascade Determines Levels of Phenotypic Heterogeneity in the Population

2015 ◽  
Vol 197 (10) ◽  
pp. 1747-1756 ◽  
Author(s):  
Laure Plener ◽  
Nicola Lorenz ◽  
Matthias Reiger ◽  
Tiago Ramalho ◽  
Ulrich Gerland ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Single Cell ◽  
Molecular Design ◽  
Vibrio Harveyi ◽  
Phenotypic Heterogeneity ◽  
Communication Process ◽  
Signaling Cascade ◽  
Homogeneous Population ◽  
Content Type ◽  
The Impact

ABSTRACTQuorum sensing (QS) is a communication process that enables a bacterial population to coordinate and synchronize specific behaviors. The bioluminescent marine bacteriumVibrio harveyiintegrates three autoinducer (AI) signals into one quorum-sensing cascade comprising a phosphorelay involving three hybrid sensor kinases: LuxU; LuxO, an Hfq/small RNA (sRNA) switch; and the transcriptional regulator LuxR. Using a new set ofV. harveyimutants lacking genes for the AI synthases and/or sensors, we assayed the activity of the quorum-sensing cascade at the population and single-cell levels, with a specific focus on signal integration and noise levels. We found that the ratios of kinase activities to phosphatase activities of the three sensors and, hence, the extent of phosphorylation of LuxU/LuxO are important not only for the signaling output but also for the degree of noise in the system. The pools of phosphorylated LuxU/LuxO per cell directly determine the amounts of sRNAs produced and, consequently, the copy number of LuxR, generating heterogeneous quorum-sensing activation at the single-cell level. We conclude that the ability to drive the heterogeneous expression of QS-regulated genes inV. harveyiis an inherent feature of the architecture of the QS cascade.IMPORTANCEV. harveyipossesses one of the most complex quorum-sensing (QS) cascades known, using three different autoinducers (AIs) to control the induction of, e.g., bioluminescence, virulence factors, and biofilm and exoprotease production. We constructed variousV. harveyimutants to study the impact of each component and subsystem of the QS signaling cascade on QS activation at the population and single-cell levels. We found that the output was homogeneous only in the presence of all AIs. In the absence of any one AI, QS activation varied from cell to cell, resulting in phenotypic heterogeneity. This study elucidates a molecular design principle which enables a tightly integrated signaling cascade to control the expression of diverse phenotypes within a genetically homogeneous population.

Electron microscopy of keratinocytes cultured on a collagen substrate used as an allograft for the treatment of chronic wounds

1992 ◽  
Vol 50 (2) ◽  
pp. 1104-1105
Author(s):  
Debby A. Jennings ◽  
Michael J. Morykwas ◽  
Louis C. Argenta
Keyword(s):  
Electron Microscopy ◽  
Cell Suspension ◽  
Single Cell ◽  
Chronic Wounds ◽  
Mechanical Stability ◽  
Uv Light ◽  
Type I ◽  
Single Cell Suspension ◽  
Collagen Substrate ◽  
Dermal Collagen

Grafts of cultured allogenic or autogenic keratlnocytes have proven to be an effective treatment of chronic wounds and burns. This study utilized a collagen substrate for keratinocyte and fibroblast attachment. The substrate provided mechanical stability and augmented graft manipulation onto the wound bed. Graft integrity was confirmed by light and transmission electron microscopy.Bovine Type I dermal collagen sheets (100 μm thick) were crosslinked with 254 nm UV light (13.5 Joules/cm2) to improve mechanical properties and reduce degradation. A single cell suspension of third passage neonatal foreskin fibroblasts were plated onto the collagen. Five days later, a single cell suspension of first passage neonatal foreskin keratinocytes were plated on the opposite side of the collagen. The grafts were cultured for one month.The grafts were fixed in phosphate buffered 4% formaldehyde/1% glutaraldehyde for 24 hours. Graft pieces were then washed in 0.13 M phosphate buffer, post-fixed in 1% osmium tetroxide, dehydrated, and embedded in Polybed 812.

Sign in / Sign up

Export Citation Format

Share Document