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:1/22/2016)... Jan. 22, 2016 ... of the "Global Biometrics Market in ... offering. --> http://www.researchandmarkets.com/research/p74whf/global_biometrics ) ... "Global Biometrics Market in Retail Sector 2016-2020" ... --> Research and Markets ( http://www.researchandmarkets.com/research/p74whf/global_biometrics ...
(Date:1/20/2016)...   MedNet Solutions , an innovative SaaS-based eClinical ... research, is pleased to announce the attainment of record-setting ... result of the company,s laser focus on (and growing ... it,s comprehensive, easy-to-use and highly affordable cloud-based technology platform. ... MedNet growth achievements in 2015 include: , ...
(Date:1/15/2016)... 15, 2016 Recent publicized breaches in cyber ... new ways to ensure data security and user authentication ... and Android that ties a user,s mobile ... into a hardware authorization token. Customer service agents who ... on their KodeKey enabled device to verify their identity. ...
Breaking Biology News(10 mins):
(Date:2/11/2016)... Feb. 11, 2016  Vermillion, Inc. (NASDAQ: VRML ... today announced the formation of the Steering Committee for ... --> Pelvic masses can present physicians ... management. Once pregnancy is ruled out, pelvic masses may ... advanced endometriosis, benign ovarian tumors and gastrointestinal and urinary ...
(Date:2/11/2016)... 2016  Wellcentive today announced it has been ... -based community care organization (CCO) with more ... quality reporting and care management solutions and services. ... of quality managers, analysts and care managers while ... serving FamilyCare members. Oregon ...
(Date:2/11/2016)... 2016   BioInformant announces the February 2016 ... Products, Opportunities, Tools, and Technologies – Market Size, Segments, ... The first and only ... industry, BioInformant has more than a decade of historical ... by stem cell type. This powerful 175 page global ...
(Date:2/10/2016)... Febr. 10, 2016 /PRNewswire/ - BioAmber Inc. (NYSE: BIOA ... announce that Mitsui & Co. Ltd., its partner in ... plant, is investing an additional CDN$25 million in the ... stake from 30% to 40%.  Mitsui will also play ... produced in Sarnia , providing dedicated ...
Breaking Biology Technology: