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:2/14/2017)... , Feb. 14, 2017  Wake Forest Baptist Medical ... its new chief executive officer (CEO). Freischlag joins the ... John D. McConnell , M.D., who last year announced ... the Medical Center, after leading it since 2008.   ... scope of Wake Forest Baptist,s academic health system, which ...
(Date:2/13/2017)... , Feb. 13, 2017 Former 9/11 Commission ... Judiciary Committee, Janice Kephart of Identity Strategy ... Donald Trump,s "Executive Order: Protecting the Nation ... 27, 2017):  "As President Trump,s ,Travel Ban, ... has now essentially banned the travel ban, it is ...
(Date:2/9/2017)... -- The biomass boiler market report by Transparency Market ... globally in terms of revenue (US$ Mn) based on ... biomass boilers has been segmented on the basis of ... market based on feedstock type, has been segmented into ... crops, urban residues, and others. On the basis of ...
Breaking Biology News(10 mins):
(Date:3/27/2017)... ... March 27, 2017 , ... ... the fight against cancer, autoimmune disease and more through a single-cell precision engineering ... and proteomics analysis platform developed in the laboratory of Dr. James Heath ...
(Date:3/27/2017)... , March 27, 2017  Perthera,s Chief Bioinformatics Officer ... Subha Madhavan , Ph.D., will be speaking at ... Panels. On Monday, March 27, 2017, she will be ... More Usable for Research and Care" (from 10:30 a.m. ... 2017, she will be a participant in the "Making ...
(Date:3/27/2017)... -- DarioHealth Corp. (NASDAQ: DRIO), a leading global digital ... today announced that it is now offering a 3 ... who want to have their DarioHealth products reimbursed by ... agreements with partners across the U.S. who will be ... will supply and bill the customer,s insurance for their ...
(Date:3/24/2017)... Biotech Ltd. ("Sinovac" or the "Company") (NASDAQ: SVA), a leading provider ... that its board of directors has amended its shareholder rights plan. The ... 2017 to March 27, 2018. The amendment was not in response to ... ... Ltd. is a China -based biopharmaceutical company that ...
Breaking Biology Technology: