Salmonella cell self-destructs for greater good of siblings

August 22nd, 2008 - 12:28 pm ICT by IANS  

London, Aug 22 (IANS) Some cells self-destruct for the sake of the greater good, thereby improving the situation of their siblings.ETH Zurich biologists investigated this unusual phenomenon using the pathogenic salmonella bacteria as an example. The microbe generates very unpleasant and life-threatening diseases.

The consumption of contaminated food, for example, egg, chicken and meat helps salmonella enter the gastro-intestinal tract where it triggers infection with spells of recurring vomiting and diarrhoea for days.

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.

But salmonellae have found a surprising solution to this conflict. Inside the gut, the salmonella 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.

What determines whether an individual salmonella bacterium cell sacrifices itself, 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.

These findings were reported by Zurich biologists Martin Ackermann and Wolf-Dietrich Hardt, in collaboration with Michael Doebeli of the University of British Columbia in Vancouver, Canada.

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