The bacterial origin of neuron communication is discovered

One of the main assets of our body is its nervous system. Our thoughts, our intelligence, how we perceive the world through our senses and how we act on it through our muscles, depend on the electrical communication between specialized cells, the neurons. Every millisecond, large amounts of charged atoms (ions) enter and leave our neurons leading to small electrical currents whose propagation allows different parts of the body (especially in the brain) to communicate very efficiently. But, how did this form of cellular communication arise?

To date, electrical communication had only been observed in relatively complex cells, starting with paramecia. But research led by Jordi García Ojalvo, director of the Dynamical Systems Biology lab of the Department of Experimental and Health Sciences (DCEXS), in close collaboration with Gürol M. Süel, adjunct lecturer at the Department of Molecular Biology of the University of California, San Diego (UCSD), shows that such simple cells as bacteria use electrical signals to communicate with each other.

It has been known for years that bacteria have ion channels, structures that allow ions to get in and out of cells. In fact, these structures have been crucial in helping scientists understand what the ion channels of the neurons in our brain are like. But, so far, how bacteria use these channels remained a mystery. The research by García Ojalvo and Süel has revealed that bacteria use ion channels to communicate when they find themselves in danger due, for example, to a lack of nutrients. This happens frequently in bacterial biofilms, cell colonies in which millions of bacteria live together when in adverse conditions. These communities help bacteria to survive better, and may constitute a clinical and environmental problem for humans, because of their extreme resistance to antibiotics and other disinfectants.

In bacterial biofilms, the bacteria from the centre are stressed because of the lack of nutrients. This study, published online in Nature on 21 October, shows that these bacteria send electrical signals to the bacteria on the periphery of the biofilm, that are less stressed, to obtain their help to survive by letting more nutrients pass. The main bargaining chip in this interaction between cells is glutamate and the associated ion is potassium. Interestingly, glutamate and potassium also play an important role in neuronal disorders like auras, waves of abnormal electrical activity that occur in the brains of people who suffer from epilepsy and migraine. It is therefore expected that the phenomenon now found in bacteria could be the precursor of such pathological behaviour in the human brain.

Reference work: Arthur Prindle, Jintao Liu, Munehiro Asally, San Ly, Jordi Garcia-Ojalvo & Gürol M. Süel. Ion channels enable electrical communication within bacterial communities. Nature, doi:10.1038/nature15709, October 2015.