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.
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).
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
Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University
New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters
Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...
Let’s say the armrest is broken in your vintage car. As things stand, you would need a lot of luck and persistence to find the right spare part. But in the world of Industrie 4.0 and production with batch sizes of one, you can simply scan the armrest and print it out. This is made possible by the first ever 3D scanner capable of working autonomously and in real time. The autonomous scanning system will be on display at the Hannover Messe Preview on February 6 and at the Hannover Messe proper from April 23 to 27, 2018 (Hall 6, Booth A30).
Part of the charm of vintage cars is that they stopped making them long ago, so it is special when you do see one out on the roads. If something breaks or...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
16.02.2018 | Information Technology
16.02.2018 | Health and Medicine
16.02.2018 | Physics and Astronomy