Kiel Life Science

Interdisciplinary Research in Life Sciences

forschung

At Kiel University, the research focus Kiel Life Science (KLS) bundles the expertise from the disciplines of bioinformatics, environmental genetics, agricultural sciences, evolutionary biology and genetics, plant breeding and animal husbandry, food sciences and evolutionary medicine. The interdisciplinary approach is also reflected in the participation of Kiel University’s most competitive faculties, research centers and major joint research projects. Common goal of all researchers involved in KLS is to advance life science research at Kiel University and to boost Kiel’s reputation as an internationally distinguished location in life sciences.

Recent publications:

Bacteria as pacemaker for the intestine

Nov 22, 2017

CAU research team discovers connection between microbiome and tissue contractions that are indispensable for healthy bowel functions

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 - 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,
doi:10.1038/s41598-017-16191-x

Photos/material is available for download:

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

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

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.: 0431-880-4170
E-Mail: tbosch@zoologie.uni-kiel.de

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

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

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

Plant escape from waterlogging

Oct 17, 2017

Researchers at Kiel University have discovered a previously unknown mechanism by which plant roots avoid oxygen-deficient soil

Researchers are warning about more frequently occurring extreme weather events in the future as a result of climate change. Current environmental catastrophes such as the numerous and particularly severe tropical hurricanes this year tend to confirm this trend. These extreme weather events are often accompanied by flooding, which increasingly affects agricultural land. This flooding is becoming an ever more serious problem for crop cultivation, because the majority of intensively grown crops are not very tolerant to too much water. Greater losses in yield are becoming apparent. At the same time, the pressure on the available agricultural land to produce crops is rapidly increasing in light of a growing global population.

In this context, CAU researchers in the Plant Developmental Biology and Plant Physiology research group at Kiel University’s Botanical Institute are looking at the effects of global climate change on plant growth. Using the example of a model plant that is frequently used in labs, Arabidopsis thaliana, also known as thale cress, doctoral researcher Emese Eysholdt-Derzsó investigated how plants respond to low oxygen stress that results from too much water. “In her work, Eysholdt-Derzsó describes for the first time how waterlogging and the related oxygen deficiency change the growth direction of thale cress roots and she deciphered which genetic mechanisms control the plants’ adaptation,” emphasized the head of the research group, Professor Margret Sauter. The Kiel-based research team recently published these new findings in the research journal Plant Physiology.

Soil conditions that are wet and hence low in oxygen are life-threatening for the majority of plants because they prevent the roots from growing and from absorbing nutrients. For a certain time, however, they can adapt to waterlogging with various protective mechanisms. The researchers at Kiel University have now examined how oxygen deficiency affects the growth and the overall root structure of thale cress. To do so, they exposed seven-day-old Arabidopsis seedlings to different oxygen regimes in alternation: they were confronted with low-oxygen growth conditions for a day, followed by normal conditions for a day. The experiments showed that the roots tried to escape the low-oxygen conditions by growing to the side. To do so, the plants use a genetically determined regulatory mechanism that prevents the normal, downwards root growth. Instead, the roots grow horizontally where it is more likely to reach more oxygen-rich soil areas. “We were able to show that this process is reversible. As soon as enough oxygen was available, the roots then started normal downwards growth again,” said the main author, Eysholdt-Derzsó.

The Kiel-based scientists called this entire process ‘root bending’. They were able to decipher the genetic regulation responsible for it: five of the overall 122 members of the ERF transcription factor family of thale cress are responsible for the roots responding to stress from too much water. They activate genes that ensure targeted distribution of the plant growth hormone, auxin, in the roots. As a consequence, this phytohormone is asymmetrically relocated in the root tissue. As auxin acts as an inhibitor, the root grows more slowly in places with higher concentrations of the hormone, causing the root to bend. The distribution of auxin in the root and thus the triggering of root bending can be seen with a fluorescence auxin marker.

Thale cress belongs to the crucifer plant family and is related to rapeseed or various cabbage plants. It is therefore highly likely that the findings gained from the model organism can be transferred to different crops. Future research will help to further investigate and understand the mechanism of root bending on other plants as well. The researchers’ long term goal is to possibly succeed in transferring the findings to crops, in order to increase their tolerance to waterlogging in the future and thus reduce agricultural yield losses.

This research project was financed as part of the German Research Foundation’s (DFG) single project funding.

Original publication:
Emese Eysholdt-Derzsó, Margret Sauter (2017): “Root bending is antagonistically affected by hypoxia and ERF-mediated transcription via auxin signaling”. Plant Physiology DOI:10.1104/pp.17.00555

Photos/material is available for download:

www.uni-kiel.de/download/pm/2017/2017-318-1.jpg
Caption: The lack of oxygen in the soil as a result of waterlogging causes the Arabidopsis root to bend (on the right of the image).
Image: Emese Eysholdt-Derzsó

www.uni-kiel.de/download/pm/2017/2017-318-2.jpg
Caption: Thale cress (Arabidopsis thaliana) is ideally suited as a model organism for lab experiments. Photo: Emese Eysholdt-Derzsó

www.uni-kiel.de/download/pm/2017/2017-318-3.jpg
Caption: The phyto-hormone auxin (fluorescent on the right hand edge of the image) inhibits the growth on one side and bends the Arabidopsis root.
Image: Emese Eysholdt-Derzsó

www.uni-kiel.de/download/pm/2017/2017-318-4.jpg
Caption: Emese Eysholdt-Derzsó, doctoral researcher in the Plant Developmental Biology and Plant Physiology research group at Kiel University, investigated root bending.
Photo: Christian Urban, Kiel University

www.uni-kiel.de/download/pm/2017/2017-318-5.jpg
Caption: The researchers used thale cress seedlings to investigate root bending. The seedlings were grown under controlled conditions.
Photo: Christian Urban, Kiel University

Contact:
Prof. Margret Sauter
Botanical Institute and Botanical Gardens, Kiel University
Tel.: +49 (0)431-880-4210
E-Mail: msauter@bot.uni-kiel.de

More information:
Plant Developmental Biology and Plant Physiology (Sauter research group),
Botanical Institute and Botanical Gardens, Kiel University:
www.sauter.botanik.uni-kiel.de

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

Kiel University
Press, Communication and Marketing, Dr. Boris Pawlowski
Address: D-24098 Kiel, phone: +49 (0431) 880-2104, fax: +49 (0431) 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
Text / Redaktion: ► Christian Urban

 

Nerves control the body’s bacterial community

Sep 26, 2017

CAU research team proves, for the first time, that there is close cooperation between the nervous system and the microbial population of the body

A central aspect of life sciences is to explore the symbiotic cohabitation of animals, plants and humans with their specific bacterial communities. Scientists refer to the full set of microorganisms living on and inside a host organism as the microbiome. Over the past years, evidence has accumulated that the composition and balance of this microbiome contributes to the organism’s health. For instance, alterations in the composition of the bacterial community are implicated in the origin of various so-called environmental diseases. However, it is still largely unknown just how the cooperation between organism and bacteria works at the molecular level and how the microbiome and body exactly act as a functional unit.

An important breakthrough in deciphering these highly complex relationships has now been achieved by a research team from Kiel University’s Zoological Institute. Using the freshwater polyp Hydra as a model organism, the Kiel-based researchers and their international colleagues investigated how the simple nervous system of these animals interacts with the microbiome. They were able to demonstrate, for the first time, that small molecules secreted by nerve cells help to regulate the composition and colonisation of specific types of beneficial bacteria along the Hydra’s body column. “Up to now, neuronal factors that influence the body’s bacterial colonisation were largely unknown. We have been able to prove that the nervous system plays an important regulatory role here,” emphasises Professor Thomas Bosch, evolutionary developmental biologist and spokesperson of the Collaborative Research Centre 1182 "Origin and Function of Metaorganisms", funded by the German Science Foundation (DFG).The scientists published their new findings in Nature Communications this Tuesday.

The research team, led by Bosch, use the freshwater polyp Hydra as the model organism to elucidate the fundamental principles of nervous system structure and function. Hydra represent an evolutionary ancient branch of the animal kingdom; they have a simple body plan with a nerve net of only about 3000 neurons. Applying modern experimental technology to these organisms that, despite their simplicity, still share a large molecular similarity with the nervous systems of vertebrates, enabled identification of ancient and therefore fundamental principles of nervous system structure and function.

Using this model organism, the researchers from Kiel University addressed the question of how messenger substances produced by the nervous system, known as neuropeptides, control the cooperation and communication between host and microbes. They collected cellular, molecular and genetic evidence to show that neuropeptides have antibacterial activity which affects both the composition and the spatial distribution of the colonizing microbes.

In order to reveal the connections between neuropeptides and bacterial communities, the Kiel-based researchers first concentrated on the development of the freshwater polyp’s nervous system, from the egg stage through to an adult animal. Cnidarians develop a complete nervous system within about three weeks. During this developmental time, the bacterial communities covering the animal’s surface change radically, until a stable composition of the microbiome finally forms. Under the influence of the antimicrobial effect of the neuropeptides, the concentration of so-called Gram-positive bacteria, a subgroup of bacteria, decreases sharply over a period of roughly four weeks. At the end of the maturing process, a typical composition of the microbiome prevails, particularly dominated by Gram-negative Curvibacter bacteria. Since the neuropeptides are particularly produced in certain areas of the body only, they also control the spatial localisation of the bacteria along the body column. Thus, in the head region, for example, there is a strong concentration of antimicrobial peptides, resulting in six times fewer Curvibacter bacteria than on the tentacles.

Based on these observations, the scientists concluded that throughout the course of evolution the nervous system also participated in a controlling role for the microbiome, in addition to its sensory and motor tasks. “The findings are also important in an evolutionary context. Since the ancestors of these animals have invented the nervous system, it seems that the interaction between the nervous system and the microbiome is an ancient feature of multicellular animals. Since the simple design of Hydra has great basic and translational relevance and promises to reveal new and unexpected basic features of nervous systems, further research into the interaction between body and bacteria will therefore concentrate more on the neuronal aspects,” said Bosch, to summarise the significance of the work.

Original publication:
René Augustin, Katja Schröder, Andrea P. Murillo Rincón, Sebastian Fraune, Friederike Anton-Erxleben, Ava-Maria Herbst, Jörg Wittlieb, Martin Schwentner, Joachim Grötzinger, Trudy M. Wassenaar, Thomas C.G. Bosch (2017): “A secreted antibacterial neuropeptide shapes the microbiome of Hydra”. Nature Communications, Published on September 26, 2017, doi:10.1038/s41467-017-00625-1
 

Photos/material is available for download:

The simple structures of the freshwater polyp Hydra make it easier to research the interaction between the nervous system and the bacterial community.
Video: Priority research area "Kiel Life Science“, Kiel University

www.uni-kiel.de/download/pm/2017/2017-294-1.jpg
Caption: Nerve cells (in green) of the freshwater polyp Hydra produce antimicrobial peptides and thus shape the animal’s microbiome. Rod-shaped bacteria can be seen at the base of the tentacles, marked in red.
Image: Christoph Giez, Dr. Alexander Klimovich

www.uni-kiel.de/download/pm/2017/2017-294-2.jpg
Caption: Fibres of intestinal tissue (in red) surround the nerve cells (in green) of the freshwater polyp Hydra.
Image: Christoph Giez, Dr. Alexander Klimovich

Contact:
Prof. Thomas Bosch,
Zoological Institute, Kiel University
Tel.: 0431-880-4170
E-Mail: tbosch@zoologie.uni-kiel.de

More information:
Collaborative Research Centre (CRC) 1182 "Origin and Function of Metaorganisms", Kiel University:
www.metaorganism-research.com

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

Kiel University
Press, Communication and Marketing, Dr. Boris Pawlowski
Address: D-24098 Kiel, phone: +49 (0431) 880-2104, fax: +49 (0431) 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
Text / Redaktion: ► Christian Urban


 

Cnidarians remotely control bacteria

Sep 21, 2017

CAU research team proves for the first time that host organisms can control the function of their bacterial symbionts

In modern life sciences, a paradigm shift is becoming increasingly evident: life forms are no longer considered to be self-contained units, but instead highly-complex and functionally-interdependent communities of organisms. The exploration of the close links between multi-cellular and especially bacterial life will, in future, be the key to a better understanding of life processes as a whole, and in particular the transition between health and illness. However, how the cooperation and communication of the organisms works in detail is currently still largely unknown. An important step forward in deciphering these multi-organism relationships has now been made by researchers from the Cell and Developmental Biology working group at Kiel University’s Zoological Institute: the scientists, led by Dr. Sebastian Fraune, have been able to prove for the first time that host organisms can control not only the composition of their colonizing bacteria, but also their function. The CAU researchers published their ground-breaking findings – derived from the example of the freshwater polyp Hydra and their specific bacterial symbionts – last Monday in the latest issue of the scientific journal Proceedings of the National Academy of Sciences.

"The starting point of our investigation was the observation that Hydra can influence the composition of species-specific bacterial colonisation, by the formation of certain antimicrobial substances," explained Dr. Cleo Pietschke, lead author of the study. In principle, these simple life forms thereby manage the same task that higher-developed organisms must also accomplish to establish a healthy microbiome: using their immune system, they ensure colonisation by the "right" composition of bacteria, and must at the same time prevent useful microorganisms from having a harmful effect. The work presented focussed on how this colonisation process is supported by the communication between host and bacteria.

Once a specific population density has been reached, bacterial communities can work together in teams, in order to fulfil certain functions. The coordination of these functions is based on a sensor mechanism, with which the individual bacteria can determine total population density with the help of signal molecules. Once a threshold value is reached, these signal molecules activate genes, and thereby regulate certain cellular functions. Using this process, known as quorum sensing, bacteria control functions such as the colonisation of surfaces, or the production of toxins.

The Kiel research team has now shown that the host organism can change the quorum sensing mechanism of the bacteria. The cnidarians thereby directly influence the bacterial signal molecules, and thus actively promote the colonisation process of their own tissue. "We have found that Hydra not only influences the presence of their bacterial symbionts, but can also directly interfere with their function," emphasised Fraune, research associate in the Cell and Developmental Biology working group. The research team described in detail, for the first time, a host using quorum quenching to inhibit the molecular communication of bacteria. Previously there were only two other examples of such interventions by a host organism. Specifically, the Kiel researchers proved that a modification of certain signal molecules by the host promotes colonisation by Curvibacter, the most frequently-occurring bacteria associated with Hydra.

The CAU researchers studied the influence of the host mechanism on its bacterial community by observing the effect of a signal molecule and its host-modified bacterial counterpart. Firstly, they brought germfree Hydra, i.e. laboratory-bred organisms without bacterial colonisation, into contact with Curvibacter bacteria. It was evident that the bacterial colonisation was poor, as long as non-modified signal molecules were present. As soon as these became modified by the influence of the host organism, the bacteria colonised the body of the cnidarians to a normal extent. The researchers then repeated the experiment on organisms that already displayed bacterial colonisation. The same pattern emerged here, too: only the host-modified signal molecules encouraged consistent and typical colonisation of the Hydra by their bacterial symbionts. Further studies are required to determine how these results, obtained from cnidarian model organisms, can be applied to other life forms. However, since Hydra are primitive evolutionary organisms, it is likely that this mechanism is also similarly present in highly-developed organisms.

"At the interface between basic research and medicine, it is becoming ever clearer that the key to health lies in the balance between the body and bacterial symbionts. In the future we have the challenging task of trying to understand the highly complex relationships between hosts and bacteria. With our new findings, we are a small step closer to achieving this," said an optimistic Fraune. In Kiel, around 70 scientists are studying the multi-organismic relationships between the body and microorganisms, together in the Collaborative Research Centre (CRC) 1182 "Origin and Function of Metaorganisms".

This work was funded by the German Research Foundation (DFG) as part of the project “Host derived mechanisms controlling bacterial colonisation at the epithelial interface in the early branching metazoan Hydra (FR 3041/2-1)” and by the Cluster of Excellence "Inflammation at Interfaces” at Kiel University.

Original publication:
Cleo Pietschke, Christian Treitz, Sylvain Forêt, Annika Schultze, Sven Künzel, Andreas Tholey, Thomas C. G. Bosch and Sebastian Fraune: “Host modification of a bacterial quorum-sensing signal induces a phenotypic switch in bacterial symbionts”. Proceedings of the National Academy of Sciences, Published on September 18, 2017
doi: 10.1073/pnas.1706879114

Photos/material is available for download:

www.uni-kiel.de/download/pm/2017/2017-292-1.jpg
Caption: The freshwater polyp Hydra.
Image: Dr Sebastian Fraune

www.uni-kiel.de/download/pm/2017/2017-292-2.jpg
Caption: Electron microscopic image of the bacterial communities (Curvibacter sp.) on the surface of Hydra.
Image: Katja Schröder

Contact:
Dr Sebastian Fraune
Zoological Institute, Kiel University
Tel.: +49 (0)431-880-4149
E-Mail: sfraune@zoologie.uni-kiel.de

More information:
Dr Sebastian Fraune,
Research associate in the Cell and Developmental Biology (Bosch group),
Zoological Institute, Kiel University
www.bosch.zoologie.uni-kiel.de/?page_id=757

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

Cluster of Excellence "Inflammation at Interfaces”, CAU Kiel:
www.inflammation-at-interfaces.de

Kiel University
Press, Communication and Marketing, Dr. Boris Pawlowski
Address: D-24098 Kiel, phone: +49 (0431) 880-2104, fax: +49 (0431) 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
Text / Redaktion: ► Christian Urban

High diversity within a simple worm

May 18, 2016

fmath-botan-inst.pngResearch team from Kiel demonstrates the importance of a natural bacterial community in one of the classical model organisms

The worm Caenorhabditis elegans is one of the best studied model organisms in biology: For decades this tiny roundworm or nematodehas been helping researchers to investigate diverse biological phenomena such as developmental processes and nervous system functions. For this work, scientists throughout the world are using a certain C. elegans strain which has been adapted to the laboratory environment and does not harbour any bacteria in its gut under these conditions. A research team from the Evolutionary Ecology and Genetics research group at Kiel University, led by Professor Hinrich Schulenburg, now demonstrated that a full appreciation of the nematode’s biology must take into account its interplay with the numerous microorganisms that live inside of the worm in nature. The Kiel researchers recently published their results on the effects of the so-called microbiome on nematode life history in the renowned journal BMC Biology.

This first systematic analysis of a natural nematode microbiome shows that the animals possess a species-rich bacterial community. Most common are Proteobacteria of the genera Pseudomonas, Stenotrophomonas or Ochrobactrum

. According to the researchers, the microbial composition is key for a more realistic view of the biology of this little worm. Their work for example showed that the natural microbiome gives the animals an evolutionary advantage and protects them against pathogens.

Even more importantly: Previously, only sterile worms were used to study various biological principles in the several hundred C. elegans

laboratories across the world. The new findings open a novel gateway into research with this worm. Scientists can now use the bacteria identified by the Schulenburg lab for their investigations in the future. "We are only at the beginning of research into the complex relationships between organisms and their associated microbes. We assume that bacteria have shaped multi-cellular life from the beginning. In future, our model will help us understand how exactly microbes influence evolution of their host organisms and in what way they determine key organismal functions such as development or immune defence against pathogens ", emphasised Schulenburg, a member of the "Kiel Life Science" research focus at Kiel University.

In order to determine the significance of the bacterial community for the worms, the researchers initially collected a total of 180 nematode samples at various sites in northern Germany, France and Portugal. The bacteria obtained from these animals were then transferred to sterile worms to study their effects on nematode life history traits. "By bringing the complex microbial community from nature into the laboratory under highly controlled conditions we can obtain a much more precise picture of the relationships between the worm as a host and its associated bacteria. This deep level of understanding would not be possible if we only studied the worms in the field", said the lead author Dr. Philipp Dirksen.

Their study approach enabled the Kiel research team to determine a central influence of the microbiome on C. elegans. The microbiome increases the fitness of the animals under normal, but also highly stressful environmental conditions. For example, worms with their microbiome are better able to produce offspring at high temperatures than sterile worms. Various Pseudomonas

bacteria also help the worms to protect themselves against fungal infections. The composition of the microbiome itself is determined by individual properties of the host, including for example their genetic characteristics. Overall worms with a natural microbiome seem to show higher fitness and reproduce at higher rates – a clear indication of an evolutionary advantage, which the bacteria provide for their host.

This new work now yields a novel and highly efficient model for the new scientific field of metaorganism research, which focusses on in-depth investigation of the interactions between organisms and their associated microorganisms. A few weeks ago the new Collaborative Research Centre (CRC) 1182 "Origin and Function of Metaorganisms" was established on this topic at Kiel University, in which Schulenburg's research group is centrally involved.

Photos/material is available for download:
Please pay attention to our ► Hinweise zur Verwendung

Click to enlarge

The Kiel research team investigated for the first time the natural bacterial community of the roundworm Caenorhabditis elegans.
Image: Antje Thomas, Hinrich Schulenburg

Image to download:
www.uni-kiel.de/download/pm/2016/2016-152-1.gif

Click to enlarge

The bacteria (coloured orange) mainly populate the digestive tract of the roundworm.
Image: Philipp Dirksen

Image to download:
www.uni-kiel.de/download/pm/2016/2016-152-2.jpg

Click to enlarge

Lead author Dr. Philipp Dirksen investigated the composition of the nematode microbiome.
Photo: Christian Urban, Kiel University

Image to download:
www.uni-kiel.de/download/pm/2016/2016-152-3.jpg

 

www.uni-kiel.de/download/pm/2016/2016-152-4.mp4

 

Three-dimensional visualisation of the microbiome of Caenorhabditis elegans

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Animation: Dr. Philipp Dirksen

 

Original publication:

 

Philipp Dirksen, Sarah Arnaud Marsh, Ines Braker, Nele Heitland, Sophia Wagner, Rania Nakad, Sebastian Mader, Carola Petersen, Vienna Kowallik, Philip Rosenstiel, Marie-Anne Félix and Hinrich Schulenburg (2016): The native microbiome of the nematode Caenorhabditis elegans: Gateway to a new host-microbiome model. BMC Biology

 

Link: http://dx.doi.org/10.1186/s12915-016-0258-1

 

 

Contact:

 

Prof. Hinrich Schulenburg
Arbeitsgruppe Evolutionsökologie und Genetik,
Zoologisches Institut, CAU Kiel
Tel.: +49 (0)431-880-4141
E-mail: hschulenburg@zoologie.uni-kiel.de

 

More information:

 

Department of Evolutionary Ecology and Genetics, Zoological Institute, CAU Kiel:
www.uni-kiel.de/zoologie/evoecogen/

 

Collaborative Research Centre (CRC) 1182 "Origin and Function of Metaorganisms", CAU Kiel:
www.metaorganism-research.org

 

Research focus "Kiel Life Science“, CAU Kiel:
www.kls.uni-kiel.de

 

Kiel University
Press, Communication and Marketing, Dr. Boris Pawlowski
Address: D-24098 Kiel, phone: +49 (0431) 880-2104, fax: +49 (0431) 880-1355
E-Mail: ► presse@uv.uni-kiel.de, Internet: ► www.uni-kiel.de
Twitter: ► www.twitter.com/kieluni, Facebook: ► www.facebook.com/kieluni
Text / Redaktion: Christian Urban

Poisonous Symbiosis

Mar 25, 2015

Scientists of Kiel University discover mechanics of poison production in Crotalaria

A working group at Kiel University (CAU) centred around Professor Dietrich Ober has discovered that symbioses between plants and bacteria are not only responsible for binding nutrients, as previously assumed, but can also be responsible for the production of plant poisons. The results were published in the prestigious journal Proceedings of the National Academy of Sciences (PNAS).

Read more

Live from the Evolution Lab

Jun 05, 2015

Study on coevolution between host and pathogens sheds new light on evolutionary dynamics.
Every year, new cold and flu pathogens occur and problematic pathogens such as Ebola cause global alarm at regular intervals. The key to a better understanding of disease epidemics lies in the adaptability and thus in the evolution of the pathogens that cause disease. With the aid of innovative experiments in the lab, researchers in the research group Evolutionary Ecology and Genetics at the Christian Albrecht University of Kiel (CAU) have now been able to gain important insights into the evolution of pathogens. To do this they examined extremely rapid, mutual adaptations of host and pathogen. The Kiel scientists have now published their results in the current edition of the prominent scientific journal PLOS Biology. Read more...

Hidden safety switch: New findings on death receptors in cancer cells

Jun 10, 2015

Achieving a better molecular understanding of the role played in the occurrence of cancer of so-called death receptors which make the progression of pancreatic cancer in particular especially aggressive and almost always fatal – this is the goal of scientists at the Institute for Experimental Tumor Research at the Christian Albrecht University of Kiel (CAU). Read more...

Hidden safety switch: New findings on death receptors in cancer cells

Jun 10, 2015

Achieving a better molecular understanding of the role played in the occurrence of cancer of so-called death receptors which make the progression of pancreatic cancer in particular especially aggressive and almost always fatal – this is the goal of scientists at the Institute for Experimental Tumor Research at the Christian Albrecht University of Kiel (CAU). The working group headed up by Professor Anna Trauzold and Professor Holger Kalthoff has been working for more than ten years now on these death receptors which can cause the controlled death of the cell, the programmed cell death, in almost all body cells and, in principle, also in cancer cells. Read more...

Live from the Evolution Lab

Jun 05, 2015

Study on coevolution between host and pathogens sheds new light on evolutionary dynamics.

 

Every year, new cold and flu pathogens occur and problematic pathogens such as Ebola cause global alarm at regular intervals. The key to a better understanding of disease epidemics lies in the adaptability and thus in the evolution of the pathogens that cause disease. With the aid of innovative experiments in the lab, researchers in the research group Evolutionary Ecology and Genetics at the Christian Albrecht University of Kiel (CAU) have now been able to gain important insights into the evolution of pathogens. Read more...

Nematode worms hitch a ride on slugs

Jul 13, 2015

2015-263-1.jpgKiel scientists expand the understanding of Caenorhabditis elegans’ natural ecology


Slugs and other invertebrates provide essential public transport for small worms including Caenorhabditis elegans in the search for food, as researchers from Kiel University have now found out. These worms are around a millimeter long and commonly found in short-lived environments, such as decomposing fruit or other rotting plant material. Read more...

Nematode worms hitch a ride on slugs

Jul 13, 2015

Kiel scientists expand the understanding of Caenorhabditis elegans’ natural ecology


Slugs and other invertebrates provide essential public transport for small worms including Caenorhabditis elegans in the search for food, as researchers from Kiel University have now found out. These worms are around a millimeter long and commonly found in short-lived environments, such as decomposing fruit or other rotting plant material. Read more...

New strategy for fighting antibiotic-resistant pathogens

Oct 16, 2015

Daily switching of antibiotics inhibits the evolution of resistance

Rapid evolution of resistance to antibiotics represents an increasingly dramatic risk for public health. In fewer than 20 years from now, antibiotic-resistant pathogens could become one of the most frequent causes of unnatural deaths. Medicine is therefore facing the particular challenge of continuing to ensure the successful treatment of bacterial infections - despite an ever-shrinking spectrum of effective antibiotics. Recent research by a group of scientists at Kiel University has now shown that there are possible ways to prolong the effectiveness of the antibiotics that are currently available. Read more...

New strategy for fighting antibiotic-resistant pathogens

Oct 16, 2015

Daily switching of antibiotics inhibits the evolution of resistance

Rapid evolution of resistance to antibiotics represents an increasingly dramatic risk for public health. In fewer than 20 years from now, antibiotic-resistant pathogens could become one of the most frequent causes of unnatural deaths. Medicine is therefore facing the particular challenge of continuing to ensure the successful treatment of bacterial infections - despite an ever-shrinking spectrum of effective antibiotics. Recent research by a group of scientists at Kiel University has now shown that there are possible ways to prolong the effectiveness of the antibiotics that are currently available. Read more...

Marine fungi contain promising anti-cancer compounds

Oct 28, 2015

fmathbotanist.png

A Kiel-based research team has identified fungi genes that can develop anti-cancer compounds

To date, the ocean is one of our planet's least researched habitats. Researchers suspect that the seas and oceans hold an enormous knowledge potential and are therefore searching for new substances to treat diseases here. In the EU "Marine Fungi" project, international scientists have now systematically looked for such substances specifically in fungi from the sea, with help from Kiel University and the GEOMAR Helmholtz Centre for Ocean Research Kiel. A particularly promising finding is the identification of the genes of one of these fungi, which are responsible for the formation of two anti-cancer compounds - so-called cyclic peptides. A research team headed by Professor Frank Kempken, Head of the Department of Genetics and Molecular Biology in Botany at Kiel University, has now published these new findings in the current edition of PLOS One. Read more...

Marine fungi contain promising anti-cancer compounds

Oct 28, 2015

A Kiel-based research team has identified fungi genes that can develop anti-cancer compounds

To date, the ocean is one of our planet's least researched habitats. Researchers suspect that the seas and oceans hold an enormous knowledge potential and are therefore searching for new substances to treat diseases here. In the EU "Marine Fungi" project, international scientists have now systematically looked for such substances specifically in fungi from the sea, with help from Kiel University and the GEOMAR Helmholtz Centre for Ocean Research Kiel. Read more...

Why the Japanese live longer

Nov 13, 2015

Kiel-based research team shows positive influence on life span of bioactive plant compounds in green tea and soy

A research team at the Institute of Human Nutrition and Food Science at Kiel University has discovered promising links between life expectancy and two phytochemicals - the so-called catechins and isoflavones. The underlying research by the Kiel-based scientists recently appeared in the two journals Oncotarget and The FASEB Journal. Read more...

New approach to antibiotic therapy is a dead end for pathogens

Jun 01, 2017

Kiel-based team of researchers uses evolutionary principles to explore sustainable antibiotic treatment strategies

The World Health Organization WHO is currently warning of an antibiotics crisis. The fear is that we are moving into a post-antibiotic era, during which simple bacterial infections would no longer be treatable. According to WHO forecasts, antibiotic-resistant pathogens could become the most frequent cause of unnatural deaths within just a few years. This dramatic threat to public health is due to the rapid evolution of resistance to antibiotics, which continues to reduce the spectrum of effective antibacterial drugs. We urgently need new treatments. In addition to developing new antibiotic drugs, a key strategy is to boost the effectiveness of existing antibiotics by new therapeutic approaches.

The Evolutionary Ecology and Genetics research group at Kiel University uses knowledge gained from evolutionary medicine to develop more efficient treatment approaches. As part of the newly-founded Kiel Evolution Center (KEC) at Kiel University, researchers under the direction of Professor Hinrich Schulenburg are investigating how alternative antibiotic treatments affect the evolutionary adaptation of pathogens. In the joint study with international colleagues now published in the scientific journal Molecular Biology and Evolution, they were able to show that in the case of the pathogen Pseudomonas aeruginosa, the evolution of resistance to certain antibiotics leads to an increased susceptibility to other drugs. This concept of so-called "collateral sensitivity" opens up new perspectives in the fight against multi-resistant pathogens.

Together with colleagues, Camilo Barbosa, a doctoral student in the Schulenburg lab, examined which antibiotics can lead to such drug sensitivities after resistance evolution. He based his work on evolution experiments with Pseudomonas aeruginosa in the laboratory. This bacterium is often multi-resistant and particularly dangerous for immunocompromised patients. In the experiment, the pathogen was exposed to ever-higher doses of eight different antibiotics, in 12-hour intervals. As a consequence, the bacterium evolved resistance to each of the drugs. In the next step, the researchers tested how the resistant pathogens responded to other antibiotics which they had not yet come into contact with. In this way, they were able to determine which resistances simultaneously resulted in a sensitivity to another drug.

The combination of antibiotics with different mechanisms of action was particularly effective - especially if aminoglycosides and penicillins were included. The study of the genetic basis of the evolved resistances showed that three specific genes of the bacterium can make them both resistant and vulnerable at the same time. "The combined or alternating application of antibiotics with reciprocal sensitivities could help to drive pathogens into an evolutionary dead end: as soon as they become resistant to one drug, they are sensitive to the other, and vice versa," said Schulenburg, to emphasize the importance of the work. Even though the results are based on laboratory experiments, there is thus hope: a targeted combination of the currently-effective antibiotics could at least give us a break in the fight against multi-resistant pathogens, continued Schulenburg.

Original publication:
Camilo Barbosa, Vincent Trebosc, Christian Kemmer, Philip Rosenstiel, Robert Beardmore, Hinrich Schulenburg and Gunther Jansen (2017): Alternative Evolutionary Paths to Bacterial Antibiotic Resistance Cause Distinct Collateral Effects. Molecular Biology and Evolution
doi.org/10.1093/molbev/msx158

Photos/material is available for download:

www.uni-kiel.de/download/pm/2017/2017-171-1.jpg
Caption: The pathogen Pseudomonas aeruginosa during the evolution experiment in the laboratory.
Image: Camilo Barbosa/Dr. Philipp Dirksen

www.uni-kiel.de/download/pm/2017/2017-171-2.jpg
Caption: Doctoral student Camilo Barbosa examined the effect of "collateral sensitivity", which can make antibiotic-resistant bacteria treatable.
Photo: Christian Urban, Kiel University

www.uni-kiel.de/download/pm/2017/2017-171-3.jpg
Caption: The research team analysed a total of 180 bacterial populations of the pathogen Pseudomonas aeruginosa.
Photo: Christian Urban, Kiel University

www.uni-kiel.de/download/pm/2017/2017-171-4.jpg
Caption: The bacteria became resistant to certain antibiotics, but at the same time sensitive to other substances.
Photo: Christian Urban, Kiel University

Contact:
Prof. Hinrich Schulenburg
Spokesperson “Kiel Evolution Center” (KEC), Kiel University
Tel.: +49 (0)431-880-4141
E-mail: hschulenburg@zoologie.uni-kiel.de

More information:
Research centre “Kiel Evolution Center”, Kiel University:
www.kec.uni-kiel.de

Evolutionary Ecology and Genetics research group, Zoological Institute, Kiel University:
www.uni-kiel.de/zoologie/evoecogen

Kiel University
Press, Communication and Marketing, Dr. Boris Pawlowski
Address: D-24098 Kiel, phone: +49 (0431) 880-2104, fax: +49 (0431) 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 Text / Redaktion: ► Christian Urban

 

Why the Japanese live longer

Nov 13, 2015

Kiel-based research team shows positive influence on life span of bioactive plant compounds in green tea and soy

A research team at the Institute of Human Nutrition and Food Science at Kiel University has discovered promising links between life expectancy and two phytochemicals - the so-called catechins and isoflavones. The underlying research by the Kiel-based scientists recently appeared in the two journals Oncotarget and The FASEB Journal. Read more...

Developmental Leaps on the Way to Becoming a Plant

Jul 10, 2017

German-Israeli research team under the leadership of Kiel University discovers evolutionary origin of redox regulation in plants

 


During the development of higher life forms over the course of millions of years, there have always been significant and comparatively sudden leaps in development. As a consequence, living organisms developed new skills and conquered additional habitats. In this process they adopted these abilities partly from their predecessor organisms: For example the plastids of the plants, the place where photosynthesis takes place, were originally autonomous unicellular living organisms. The developmental transformation of cyanobacteria into such cell organelles - the endosymbiosis, provided the plant cell with the ability to photosynthesize and thus the ability to produce energy from sunlight. Apparently, a similarly important common characteristic of plants and higher living organisms developed in a comparable manner: An international research team from the Institute of General Microbiology at Kiel University (CAU) and from the Israeli Weizmann Institute of Science has found evidence that the redox regulation in plant metabolism has its origin in two successive plastid endosymbiosis events. The results of the work funded by the Kiel Cluster of Excellence “The Future Ocean” have recently been published by the international research team in the renowned journal Nature Plants.

The development of plastids is of fundamental importance in the evolution of plants. Seen from a global perspective, plastids also boosted the so-called primary production, and thus provided oxygen and the nutritional basis for all life on Earth. To an extent, the cell paid an evolutionary price for the newly acquired advantage of energy production through photosynthesis. It had to react to the formation of highly reactive and potentially harmful byproducts, the radicals. Interestingly, cells have evolved the ability to sense the level of free radicals and use this information to regulate their metabolic activity by a unique type of control mechanism - redox regulation. Since oxygen in particular tends to develop radical molecules, the redox regulation gained its importance with the higher availability of oxygen in Earth’s past – a time period, which is associated with the fundamental developmental leap to multicellar life forms. In order to investigate the evolutionary origin of redox regulation, Dr. Christian Wöhle, research associate in the working group Genomic Microbiology at Kiel University, compared the redox regulated protein network of the diatom Phaeodactylum tricornutum to living organisms of various other phyla. As an evolutionarily quite simple life form, the diatom already has traits of more highly developed organisms; like plants it is able to carry out photosynthesis. In this manner, this model organism allows conclusions to higher developed plant and animal life forms to be drawn. 

Together with their international colleagues, the researchers from Kiel recognized that the development of the redox regulation of higher living organisms coincided with the process of a multistage plastid endosymbiosis. Comparison with the protein sequences of diverse predecessor organisms has shown that a sudden increase in the occurrence of redox regulated proteins took place in the predecessors of the diatoms, at the same time as the first plastids were taken up. The redox sensitive proteins change their biochemical characteristics if they come into contact with radicals. In this manner they allow the organism to adjust its metabolism to changing environmental conditions. “We were able to observe that the proteins, which are responsible for metabolism in the development of complex plant organisms always changed when new cell organelles were added”, emphasizes Wöhle, lead author of the study.

The mechanism by which the diatoms acquired the ability to be redox-regulated  consists in a transition of the genetic information from the subsequently acquired plastids into the genome of the receptive organism. The scientists found out that more than half of the genes involved in the redox regulation originate from unicellular organisms, in this case cyanobacteria. This observation supports the theory of the research team that the cell’s ability to conduct redox regulation developed through endosymbiotic gene transfer and thus laid the foundation for the development of higher plants. “Our results allow insight into the evolutionary adaptation of life to photosynthetic energy production and the resulting required expanded regulation mechanisms of the plant cell. They help us to better understand the reaction of different organisms to a long-term change in their living conditions,” summarizes co-author Professor Tal Dagan, head of the working group Genomic Microbiology at Kiel University and member of the “Kiel Evolution Center” (KEC). 
    
Original work:
Christian Wöhle, Tal Dagan, Giddy Landan, Assaf Vardi & Shilo Rosenwasser “Expansion of the redox-sensitive proteome coincides with the plastid endosymbiosis” Nature Plants, Published on May 15, 2017, 
doi:10.1038/nplants.2017.66

Images for download under:
www.uni-kiel.de/download/pm/2017/2017-225-1.jpg 
Caption: Phaeodactylum tricornutum cells showing fluorescent organelles: The nucleus is coloured in green, chloroplasts appear in red.
Image: Shiri Graff van Creveld, The Weizmann Institute of Science

Contact:
Prof. Tal Dagan
Genomic Microbiology 
Institute of General Microbiology, Kiel University
Telephone: 0431 880-5712
E-Mail: tdagan@ifam.uni-kiel.de

Dr. Christian Wöhle
Genomic Microbiology 
Institute of General Microbiology, Kiel University
Telephone: 0431 880-5744
E-Mail: cwoehle@ifam.uni-kiel.de

Further Information:
Genomic Microbiology (AG Dagan)
Institute of General Microbiology, Kiel University
www.mikrobio.uni-kiel.de/de/ag-dagan

Cluster of Excellence “The Future Ocean”, Kiel University:
www.futureocean.org

Research Center “Kiel Evolution Center“, Kiel University:
www.kec.uni-kiel.de

Kiel University
Press, Communication and Marketing, Dr. Boris Pawlowski, Text/Editing: Christian Urban 
Postaal address: D-24098 Kiel, Telephone: (0431) 880-2104, Telefax: (0431) 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

Switching mutations on and off again

Apr 12, 2016

Kiel research team facilitates functional genomics with new procedure

 

Mould is primarily associated with various health risks. However, it also plays a lesser-known role, but one which is particularly important in biotechnology. The mould (ascomycete) Aspergillus niger, for example, has been used for for around 100 years to industrially produce citric acid, which is used as a preservative additive in many foodstuffs. In order to research the genetic mechanisms which could shed light on the potential application spectrum of mould and its metabolic products, a research team from Kiel University has developed a new procedure in collaboration with colleagues from Leiden University in the Netherlands.  Read more...

New approach to antibiotic therapy is a dead end for pathogens

Jun 01, 2017

Kiel-based team of researchers uses evolutionary principles to explore sustainable antibiotic treatment strategies

The World Health Organization WHO is currently warning of an antibiotics crisis. The fear is that we are moving into a post-antibiotic era, during which simple bacterial infections would no longer be treatable. According to WHO forecasts, antibiotic-resistant pathogens could become the most frequent cause of unnatural deaths within just a few years. This dramatic threat to public health is due to the rapid evolution of resistance to antibiotics, which continues to reduce the spectrum of effective antibacterial drugs. We urgently need new treatments. In addition to developing new antibiotic drugs, a key strategy is to boost the effectiveness of existing antibiotics by new therapeutic approaches.

The Evolutionary Ecology and Genetics research group at Kiel University uses knowledge gained from evolutionary medicine to develop more efficient treatment approaches. As part of the newly-founded Kiel Evolution Center (KEC) at Kiel University, researchers under the direction of Professor Hinrich Schulenburg are investigating how alternative antibiotic treatments affect the evolutionary adaptation of pathogens. In the joint study with international colleagues now published in the scientific journal Molecular Biology and Evolution, they were able to show that in the case of the pathogen Pseudomonas aeruginosa, the evolution of resistance to certain antibiotics leads to an increased susceptibility to other drugs. This concept of so-called "collateral sensitivity" opens up new perspectives in the fight against multi-resistant pathogens.

Together with colleagues, Camilo Barbosa, a doctoral student in the Schulenburg lab, examined which antibiotics can lead to such drug sensitivities after resistance evolution. He based his work on evolution experiments with Pseudomonas aeruginosa in the laboratory. This bacterium is often multi-resistant and particularly dangerous for immunocompromised patients. In the experiment, the pathogen was exposed to ever-higher doses of eight different antibiotics, in 12-hour intervals. As a consequence, the bacterium evolved resistance to each of the drugs. In the next step, the researchers tested how the resistant pathogens responded to other antibiotics which they had not yet come into contact with. In this way, they were able to determine which resistances simultaneously resulted in a sensitivity to another drug.

The combination of antibiotics with different mechanisms of action was particularly effective - especially if aminoglycosides and penicillins were included. The study of the genetic basis of the evolved resistances showed that three specific genes of the bacterium can make them both resistant and vulnerable at the same time. "The combined or alternating application of antibiotics with reciprocal sensitivities could help to drive pathogens into an evolutionary dead end: as soon as they become resistant to one drug, they are sensitive to the other, and vice versa," said Schulenburg, to emphasize the importance of the work. Even though the results are based on laboratory experiments, there is thus hope: a targeted combination of the currently-effective antibiotics could at least give us a break in the fight against multi-resistant pathogens, continued Schulenburg.

Original publication:
Camilo Barbosa, Vincent Trebosc, Christian Kemmer, Philip Rosenstiel, Robert Beardmore, Hinrich Schulenburg and Gunther Jansen (2017): Alternative Evolutionary Paths to Bacterial Antibiotic Resistance Cause Distinct Collateral Effects. Molecular Biology and Evolution
doi.org/10.1093/molbev/msx158

Photos/material is available for download:

www.uni-kiel.de/download/pm/2017/2017-171-1.jpg
Caption: The pathogen Pseudomonas aeruginosa during the evolution experiment in the laboratory.
Image: Camilo Barbosa/Dr. Philipp Dirksen

www.uni-kiel.de/download/pm/2017/2017-171-2.jpg
Caption: Doctoral student Camilo Barbosa examined the effect of "collateral sensitivity", which can make antibiotic-resistant bacteria treatable.
Photo: Christian Urban, Kiel University

www.uni-kiel.de/download/pm/2017/2017-171-3.jpg
Caption: The research team analysed a total of 180 bacterial populations of the pathogen Pseudomonas aeruginosa.
Photo: Christian Urban, Kiel University

www.uni-kiel.de/download/pm/2017/2017-171-4.jpg
Caption: The bacteria became resistant to certain antibiotics, but at the same time sensitive to other substances.
Photo: Christian Urban, Kiel University

Contact:
Prof. Hinrich Schulenburg
Spokesperson “Kiel Evolution Center” (KEC), Kiel University
Tel.: +49 (0)431-880-4141
E-mail: hschulenburg@zoologie.uni-kiel.de

More information:
Research centre “Kiel Evolution Center”, Kiel University:
www.kec.uni-kiel.de

Evolutionary Ecology and Genetics research group, Zoological Institute, Kiel University:
www.uni-kiel.de/zoologie/evoecogen

Kiel University
Press, Communication and Marketing, Dr. Boris Pawlowski
Address: D-24098 Kiel, phone: +49 (0431) 880-2104, fax: +49 (0431) 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 Text / Redaktion: ► Christian Urban

 

Bacteria as pacemaker for the intestine

Nov 22, 2017

CAU research team discovers connection between microbiome and tissue contractions that are indispensable for healthy bowel functions

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 - 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,
doi:10.1038/s41598-017-16191-x

Photos/material is available for download:

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

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

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.: 0431-880-4170
E-Mail: tbosch@zoologie.uni-kiel.de

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

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

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

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