Bacteria as pacemaker for the intestine

Body contractions in Hydra are triggered by nerve cells (in green), while bacteria (rod-shaped cells in red) influence the underlying pacemaker activity. Image: Christoph Giez, Dr. Alexander Klimovich

Spontaneous contractions of the digestive tract play an important role in almost all animals, and ensure healthy bowel functions. From simple invertebrates to humans, there are consistently similar patterns of movement, through which rhythmic contractions of the muscles facilitate the transport and mixing of the bowel contents.

These contractions, known as peristalsis, are essential for the digestive process. With various diseases of the digestive tract, such as severe inflammatory bowel diseases in humans, there are disruptions to the normal peristalsis.

To date, very little research has explored the factors underlying the control of these contractions. Now, for the first time, a research team from the Cell and Developmental Biology (Bosch AG) working group at the Zoological Institute at Kiel University (CAU) has been able to prove that the bacterial colonisation of the intestine plays an important role in controlling peristaltic functions.

The scientists published their results yesterday – derived from the example of freshwater polyps Hydra – in the latest issue of Scientific Reports.

The triggers for the normal spontaneous contractions of the muscle tissue are so-called pacemaker cells of the nervous system. In a specific rhythm and without any external stimulation, they emit electrical impulses, that ultimately reach the smooth muscles of the intestinal wall, and cause them to contract. Although the impulses as such occur by themselves, their frequency and intensity, however, are subject to external influences.

“The example of the simple freshwater polyp Hydra has shown us that the bacterial colonisation of the organism can affect the contractions of its digestive cavity. Most likely they do so by modulating the underlying pacemaker signals,” said Professor Thomas Bosch, head of the study and spokesperson for the Collaborative Research Centre (CRC) 1182 “Origin and Function of Metaorganisms”.

Unlike other more complex organisms, Hydra have no bowel in the true sense of the word. Their simple body cavity assumes, amongst other things, the function of a digestive tract; the surrounding tissue also exhibits the typical contractions associated with more highly-developed intestines.

To find out how peristalsis is regulated in the freshwater polyps, the researchers compared normal Hydra which had typical bacterial colonisation with those that had their microbiome completely removed with an antibiotic cocktail. In comparison, these organisms without bacterial colonisation – also referred to as germ-free polyps – exhibited a reduction in contractions by about half. At the same time, the rhythm of the movements became disrupted, and some of the breaks between the contractions were much longer. Thus, the absence of the typical microbiome in Hydra compromised the peristaltic movements in the body cavity.

In a further step, the scientists restored the specific bacterial colonisation in the germ-free organisms. Initially, they introduced each of the five most common bacterial species found in the Hydra microbiome individually back into the sterile polyps. It turned out that this individual bacterial colonisation has no appreciable effect on the frequency and timing of contractions. Only the joint re-introduction of the five main representatives of the microbiome led to a marked improvement in peristalsis, although even then, the pattern of contractions was not fully normalised. Interestingly, an extract produced from the colonising bacteria had a similarly positive influence.

From these observation the Kiel research team concluded that only the natural Hydra microbiome – characterised by a balance between the bacterial species present – can play an important pacemaker role in peristalsis. They discovered that, in this case, certain molecules secreted by the bacteria can intervene in the control mechanism of the pacemaker cells. As such, bacterial signals can have a decisive effect on the pattern of spontaneous peristaltic contractions. “We were able to demonstrate for the first time that in our simple model organism, the microbiome has an indispensable function in the frequency and timing of tissue contractions,” emphasised Bosch.

In addition, the example of the evolutionarily ancient model organism Hydra shows us that the control of vital processes of multicellular organisms by their bacterial symbionts already originated very early in the evolution of life, continued Bosch. These ground-breaking results are especially promising for medical research: “The fundamental explanation of the cooperation between organism and microbiome in regulating peristalsis will in future help us to understand the emergence of severe diseases, which arise from disrupted movement of the intestine,” summarised Bosch.

Original publication:
Andrea P. Murillo-Rincón, Alexander Klimovich, Eileen Pemöller, Jan Taubenheim, Benedikt Mortzfeld, René Augustin & Thomas C.G. Bosch (2017): “Spontaneous body contractions are modulated by the microbiome of Hydra”. Scientifc Reports, Published on 21.11.2017, https://www.nature.com/articles/s41598-017-16191-x

Photos are available to download:
http://www.uni-kiel.de/download/pm/2017/2017-368-1.gif
Caption: The typical contraction pattern of the freshwater polyp Hydra: Contraction and relaxation of the same animal over the course of three minutes.
Animation: Andrea Murillo-Rincon, Dr. Alexander Klimovich

http://www.uni-kiel.de/download/pm/2017/2017-368-2.jpg
Caption: Body contractions in Hydra are triggered by nerve cells (in green), while bacteria (rod-shaped cells in red) influence the underlying pacemaker activity.
Image: Christoph Giez, Dr. Alexander Klimovich

http://www.uni-kiel.de/download/pm/2017/2017-368-3.jpg
Caption: Hydra’s nerve cells (in green) generate electrical impulses that cause contractions of muscle fibers (shown in red) in the gastric cavity wall.
Image: Christoph Giez, Dr. Alexander Klimovich

Contact:
Prof. Thomas Bosch
Zoological Institute, Kiel University
Tel.: +49 (0)431-880-4170
E-mail: tbosch@zoologie.uni-kiel.de

More information:
Priority research area “Kiel Life Science”, Kiel University
http://www.kls.uni-kiel.de

Collaborative Research Centre (CRC) 1182 “Origin and Function of Metaorganisms”, Kiel University:
http://www.metaorganism-research.com

Cell and Developmental Biology (Bosch AG) working group,
Zoological Institute, Kiel University:
http://www.bosch.zoologie.uni-kiel.de

Christian-Albrechts-Universität zu Kiel
Press, Communication and Marketing, Dr Boris Pawlowski, Text: Christian Urban
Postal address: D-24098 Kiel, Germany, Telephone: +49 (0)431 880-2104, Fax: +49 (0)431 880-1355
E-mail: presse@uv.uni-kiel.de, Internet: www.uni-kiel.de, Twitter: www.twitter.com/kieluni
Facebook: www.facebook.com/kieluni, Instagram: www.instagram.com/kieluni

Media Contact

Dr. Boris Pawlowski Christian-Albrechts-Universität zu Kiel

All news from this category: Life Sciences

Articles and reports from the Life Sciences area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to the Homepage

Comments (0)

Write comment

Latest posts

Innovations through hair-thin optical fibres

Scientists at the University of Bonn have built hair-thin optical fibre filters in a very simple way. They are not only extremely compact and stable, but also colour-tunable. This means…

Artificial intelligence for sustainable agriculture

ZIM cooperation network on AI-based agricultural robotics launched The recently approved ZIM cooperation network “DeepFarmbots” met virtually for its official kick-off on November 25. The central goal of the network…

Teamwork in a molecule

Chemists at the University of Jena harness synergy effect of gallium Chemists at Friedrich Schiller University Jena have demonstrated the value of “teamwork” by successfully harnessing the interaction between two…

Partners & Sponsors

By continuing to use the site, you agree to the use of cookies. more information

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.

Close