Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

ETH Zurich study on salmonella self-destruction

22.08.2008
Self-destruction for a common cause

ETH Zurich biologists, led by Professors Martin Ackermann and Wolf-Dietrich Hardt, in collaboration with Michael Doebeli of the University of British Colombia in Vancouver (CN), have been able to describe how random molecular processes during cell division allow some cells to engage in a self-destructive act to generate a greater common good, thereby improving the situation of the surviving siblings.

Survival strategy

The biologists investigated this unusual biological concept using the pathogenic salmo-nella bacteria as an example. Diseases caused by salmonellae are very unpleasant and even life-threatening. When contaminated food is consumed – for example, egg-based foods or chicken and meat – salmonella bacteria enter the gastro-intestinal tract where it triggers infection. Vomiting and diarrhoea can last for days.

Normally, salmonellae grow poorly in the intestine because they are not competitive with other bacteria of the gut. However, this dynamic changes if salmonellae induce an inflammatory response, namely diarrhoea, which suppresses the other bacteria. The inflammation is triggered by salmonellae penetrating into the intestinal tissues. Once inside, salmonellae is killed by the immune system. This in turn creates a conflict: salmonellae are either suppressed by the other bacteria in the gut, or die while trying to eliminate these competitors.

As Ackermann, Hardt and Doebeli report, salmonellae have found a surprising solution to this conflict. Inside the gut, the samonella bacteria forms two groups that engage in job-sharing. A first group invades the tissue, triggers an inflammation, then dies. A second group waits inside the gut until the inactivation of the normal intestinal flora gives them an opportunity to strike.This second group then multiplies unhindered.

Random processes and self-sacrifice

What determines whether an individual salmonella bacterium cell self-sacrifices, or whether it will wait and benefit from the sacrifice of others? The two groups are clones of the same genotype, so genetic differences do not play a role. Rather, the difference between the two groups is a result of random molecular processes during cell division. Cellular components are randomly distributed between the two daughter cells with each cell receiving a different amount. The resulting imbalance can be amplified and lead to different properties of the clonal siblings.

In recent years it has been recognized that such random processes in a cell can have a large influence on individual cells. The work by the ETH Zurich researchers reveals a new biological explanation for this phenomenon. The two salmonella phenotypes share their work, with the result being that they achieve what a single phenotype on its own would not be capable of doing. This scenario is fundamentally different from the usual explanations and presupposes that individual phenotypes interact and have an effect on one another. The self-sacrifice of phenotypes may be quite common among pathogenic bacteria, for example, among the pathogens causing diarrhoea after antibiotic treatment (clostridia) or pneumonia (streptococci).

Essential findings

Professor Ackermann says that “Random processes could promote job-sharing in many different types of organisms.” Many bacteria manufacture substances which are toxic to their hosts but which are only released into the host environment if the bacteria sacrifice themselves - if this is the sole method to get the toxin out of the cell. This is why every cell makes a decision: toxin and death or no toxin.

He stresses that it would not have been possible to study this theory so thoroughly with-out the collaboration that took place among the three specialist groups: Professor Hardt’s group specialises in salmonella infections; Professor Doebeli is a mathematician and theoretical biologist; and Professor Ackermann’s group focuses on phenotypic noise.

Roman Klingler | alfa
Further information:
http://www.cc.ethz.ch

More articles from Studies and Analyses:

nachricht Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>