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Bacteria avoid age defects through collective behavior

Date:
July 14, 2016
Source:
University of Copenhagen - Niels Bohr Institute
Summary:
Biophysics: As they age, more and more defects arise in most organisms. Researchers have discovered that microorganisms like bacteria can keep a colony young by practicing a common strategy for propagation. The same may be true for, for example, stem cells in humans.
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Microscopic image of bacteria that have formed by dividing from a single cell. The cells were exposed to heat stress. The green spots show cell damage. The greatest damage is on the older cells, while the younger cells have little or no damage.
Credit: Ala Trusina

Biophysics: As they age, more and more defects arise in most organisms. Researchers from the Niels Bohr Institute have discovered that microorganisms like bacteria can keep a colony young by practicing a common strategy for propagation. The same may be true for, for example, stem cells in humans. The results have been published in the scientific journal, Cell Systems.

Microorganisms like bacteria reproduce by growing and dividing into two new bacteria. The older the bacteria, the more defects they have accumulated. When bacteria divide, the two new bacteria look the same, but the question is whether the defects are divided equally between the two new individuals.

"We wanted to investigate whether the bacteria divided symmetrically with an equal number of defects in both new individuals or whether divided asymmetrically with more defects in one new bacteria than the other," explains Ala Trusina, an associate professor in Biocomplexity at the Niels Bohr Institute at the University of Copenhagen.

Microscopic image of bacteria that have formed by dividing from a single cell. The cells were exposed to heat stress. The green spots show cell damage. The greatest damage is on the older cells, while the younger cells have little or no damage. (Credit: Ala Trusina)

The researchers performed experiments in the laboratory and made model calculations. They wanted to investigate what was best for the bacterial community. Would it be best to have a colony that was aged to the same degree? Or would it be better for the colony to have the aging defects accumulate in some individuals, while others were free of aging defects and were thus younger?

The environment controls the colony

In the laboratory they studied the bacterial colonies under different conditions and influences. The measurements showed that when a colony was left in peace, the bacteria shared almost symmetrically, so the new individuals were fairly similar with the same number of defects.

However, if they exposed the colony to 'stress' in the form of heat or bacteriostatic compounds, cell division was asymmetrical. Now the defects gathered in one bacterium, which then aged and also grew at a slower rate.

"What we have found is that the asymmetry of cell division is not controlled genetically. It is a process that is controlled by the physical environment. Through collective behaviour, the bacterial colony that is exposed to stress can stay young, produce more offspring and keep the colony healthier. This is completely new knowledge that has never been observed before," explains Ala Trusina.

She explains that the knowledge could have great potential, as it is a process that is probably universal and applies to cells in many organisms, including for stem cells. A single individual cell cannot overcome the damage, but the group of cells can do so together. The strength lies in the collective behaviour.


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Materials provided by University of Copenhagen - Niels Bohr Institute. Note: Content may be edited for style and length.


Journal Reference:

  1. Søren Vedel, Harry Nunns, Andrej Košmrlj, Szabolcs Semsey, Ala Trusina. Asymmetric Damage Segregation Constitutes an Emergent Population-Level Stress Response. Cell Systems, 2016 DOI: 10.1016/j.cels.2016.06.008

Cite This Page:

University of Copenhagen - Niels Bohr Institute. "Bacteria avoid age defects through collective behavior." ScienceDaily. ScienceDaily, 14 July 2016. <www.sciencedaily.com/releases/2016/07/160714135120.htm>.
University of Copenhagen - Niels Bohr Institute. (2016, July 14). Bacteria avoid age defects through collective behavior. ScienceDaily. Retrieved May 25, 2017 from www.sciencedaily.com/releases/2016/07/160714135120.htm
University of Copenhagen - Niels Bohr Institute. "Bacteria avoid age defects through collective behavior." ScienceDaily. www.sciencedaily.com/releases/2016/07/160714135120.htm (accessed May 25, 2017).

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