Navigation Links
A matter of density, not quantity
Date:7/10/2009

This release is available in German.

Infections of wounds, pneumonia, etc. in hospitals in particular are often caused by bacteria called Pseudomonas aeruginosa. Once they reach a certain density, colonies of Pseudomonas aeruginosa produce virulence factors and can enter into a slimy state, a biofilm, which prevents antibiotics from penetrating. The process of quorum sensing, which cells use to "sense" cell density, is triggered when the concentration of certain signaling compounds generated by the bacteria reaches a threshold level. A team working with Rustem F. Ismagilov at the University of Chicago has now demonstrated that the absolute number of cells is irrelevant; only the number of bacteria in a given volume plays a role. As the researchers report in the journal Angewandte Chemie, they were even able to trigger quorum-sensing processes in single cells when these were confined in extremely small volumes.

The term, quorum sensing, is derived from the Latin quorum; in politics, this is the number of votes that must be cast for an election or referendum to be valid. In biology, quorum sensing is defined as a process by which cells are able to detect the accumulation of a released signal and then change their behavior when the signal concentration exceeds a threshold level. Traditionally, quorum sensing is thought to help microorganisms to coordinate processes that would be inefficient in single cells, such as the formation of biofilms. Quorum sensing can also prevent too many bacteria from colonizing too small an area. However, the work of Ismagilov's team has shown that quorum sensing is also activated by a single cell if the cell finds itself in an extremely enclosed space, which raises questions as to how quorum-sensing-regulated processes are relevant both to large colonies of cells and to single cells in confined spaces.

In order to investigate this phenomenon, two different approaches can be taken: either seed a macroscopic volume with bacteria and wait for them to reach the required population through cell division, or enclose a few cells in an extremely tiny volume. The necessary signaling compounds can also become sufficiently concentrated by this route because the released signals cannot diffuse far away from the cell but instead accumulate around the cell. "In the past, the first strategy has dominated. This has led to the general view that quorum sensing is a process to coordinate the behavior of large groups of cells," says Ismagilov. "This overlooks the possibility that small groups of cells could also initiate quorum sensing if they are confined to a sufficiently small volume. The quorum-sensing metabolic processes are relevant to a number of cellular functions, including the growth of small numbers of cells at the early stages of biofilm formation or the early stages of an infection."

By using a microfluidic experimental array, the team was able to isolate droplets with a volume of about 100 femtoliters (100 quadrillionths of a liter), each containing only one or very few cells of Pseudomonas aeruginosa. Even with these extremely low cell counts, the researchers were able to observe that quorum sensing was triggered in many cases. "This unambiguously refutes the notion that millions of cells are required for quorum sensing," says Ismagilov.


'/>"/>

Contact: Rustem F. Ismagilov
r-ismagilov@uchicago.edu
773-702-5816
Wiley-Blackwell
Source:Eurekalert

Related biology news :

1. Primate sperm competition: speed matters
2. How size matters
3. Nitrous oxide: definitely no laughing matter
4. Dissolved organic matter in the water column may influence coral health
5. Getting to the root of the matter
6. In spiders, size matters: Small males are more often meals
7. Caltech-led researchers find negative cues from appearance alone matter for real elections
8. Global warming is changing organic matter in soil
9. Sequence matters in droughts and floods
10. Penn biologists demonstrate that size matters... in snail shells
11. Shape matters in the case of cobalt nanoparticles
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/11/2017)... , April 11, 2017 NXT-ID, Inc. ... technology company, announces the appointment of independent Directors Mr. ... to its Board of Directors, furthering the company,s corporate governance ... Gino ... we look forward to their guidance and benefiting from their ...
(Date:4/4/2017)... , April 4, 2017   EyeLock LLC , ... that the United States Patent and Trademark Office (USPTO) ... covers the linking of an iris image with a ... and represents the company,s 45 th issued patent. ... is very timely given the multi-modal biometric capabilities that ...
(Date:3/29/2017)...  higi, the health IT company that operates the ... , today announced a Series B investment from ... The new investment and acquisition accelerates higi,s strategy to ... population health activities through the collection and workflow integration ... collects and secures data today on behalf of over ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... and LAGUNA HILLS, Calif. , ... of Cancer Research, London (ICR) and ... with SKY92, SkylineDx,s prognostic tool to risk-stratify patients with multiple ... as MUK nine . The University of ... is partly funded by Myeloma UK, and ICR will perform ...
(Date:10/10/2017)... (PRWEB) , ... October 10, ... ... development-stage cancer-focused pharmaceutical company advancing targeted antibody-drug conjugate (ADC) therapeutics, today confirmed ... targeted HPLN (Hybrid Polymerized Liposomal Nanoparticle), a technology developed in collaboration with ...
(Date:10/10/2017)... ... October 10, 2017 , ... USDM Life Sciences ... the life sciences and healthcare industries, announces a presentation by Subbu Viswanathan and ... presentation, “Automating GxP Validation for Agile Cloud Platforms,” will present a revolutionary approach ...
(Date:10/9/2017)... ... October 09, 2017 , ... The Giving Tree Wellness Center ... the needs of consumers who are incorporating medical marijuana into their wellness and ... , As operators of two successful Valley dispensaries, The Giving Tree’s two founders, ...
Breaking Biology Technology: