Press releases – May 2020

 

May 26 2020
12:43

Unique long-term videos show the bee nursery in the hive 

Honeybees: pesticides disrupt nursing behaviour and larval development 

FRANKFURT. A newly developed video technique has allowed scientists at Goethe University Frankfurt at the Bee Research Institute of the Polytechnical Society to record the complete development of a honey bee in its hive for the first time. It also led to the discovery that certain pesticides – neonicotinoids – changed the behaviour of the nurse bees: researchers determined that they fed the larvae less often. Larval development took up to 10 hours longer. A longer development period in the hive can foster infestation by parasites such as the Varroa mite (Scientific Reports, DOI 10.1038/s41598-020-65425-y).

Honey bees have very complex breeding behaviour: a cleaning bee cleans an empty comb (brood cell) of the remains of the previous brood before the queen bee lays an egg inside it. Once the bee larva has hatched, a nurse bee feeds it for six days. Then the nurse bees caps the brood cell with wax. The larva spins a cocoon and goes through metamorphosis, changing the shape of its body and developing a head, wings and legs. Three weeks after the egg was laid, the fully-grown bee hatches from the cocoon and leaves the brood cell.

Using a new video technique, scientists at Goethe University Frankfurt have now succeeded for the first time in recording the complete development of a honey bee in a bee colony at the Bee Research Institute of the Polytechnical Society. The researchers built a bee hive with a glass pane and were thus able to film a total of four bee colonies simultaneously over several weeks with a special camera set-up. They used deep red light so that the bees were not disturbed, and recorded all the movements of the bees in the brood cells.

The researchers were particularly interested in the nursing behaviour of the nurse bees, to whose food (a sugar syrup) they added small amounts of pesticides known as neonicotinoids. Neonicotinoids are highly effective insecticides that are frequently used in agriculture. In natural environments, neonicotinoids arrive in bee colonies through nectar and pollen collected by the bees. It is already known that these substances disturb the navigational abilities and learning behaviour of bees. In a measure criticised by the agricultural industry, the European Union has prohibited the use of some neonicotinoids in crop cultivation.

Using machine learning algorithms developed by the scientists together with colleagues at the Centre for Cognition and Computation at Goethe University, they were able to evaluate and quantify the nursing behaviour of the nurse bees semi-automatically. The result: even small doses of the neonicotinoids Thiacloprid or Clothianidin led to the nurse bees feeding the larva during the 6-day larval development less frequently, and consequently for a shorter daily period. Some of the bees nursed in this manner required up to10 hours longer until the cell was capped with wax.

“Neonicotinoids affect the bees' nervous systems by blocking the receptors for the neurotransmitter acetylcholine," explains Dr Paul Siefert, who carried out the experiments in Professor Bernd Grünewald's work group at the Bee Research Institute Oberursel. Siefert: “For the first time, we were able to demonstrate that neonicotinoids also change the social behaviour of bees. This could point to the disruptions in nursing behaviour due to neonicotinoids described by other scientists." Furthermore, parasites such as the feared Varroa mite (Varroa destructor) profit from an extended development period, since the mites lay their eggs in the brood cells shortly before they are capped: if they remain closed for a longer period, the young mites can develop and multiply without interruption.

However, according to Siefert, it still remains to be clarified whether the delay in the larval development is caused by the behavioural disturbance of the nurse bee, or whether the larvae develop more slowly because of the altered jelly. The nurse bees produce the jelly and feed it to the larvae. “From other studies in our work group, we know that the concentration of acetylcholine in the jelly is reduced by neonicotinoids," says Siefert. “On the other hand, we have observed that with higher dosages, the early embryonal development in the egg is also extended – during a period in which feeding does not yet occur." Additional studies are needed to determine which factors are working together in these instances.

In any case, the new video technique and the evaluation algorithms offer great potential for future research projects. In addition to feeding, behaviours for heating and construction were also able to be reliably identified. Siefert: “Our innovative technology makes it possible to gain fundamental scientific insights into social interactions in bee colonies, the biology of parasites, and the safety of pesticides."

Publication: Paul Siefert, Rudra Hota, Visvanathan Ramesh, Bernd Grünewald. Chronic within-hive video recordings detect altered nursing behaviour and retarded larval development of neonicotinoid treated honey bees. Sci. Rep. 10, 8727 (2020).

Video: Development of a bee larva https://www.nature.com/articles/s41598-020-65425-y (Supplementary Material)

Images may be downloaded here:  http://www.uni-frankfurt.de/88682581

Captions:

Figure 1: Diagram/monitoring of brood cells – side view of the construction and camera view of the brood area. The brood area of the bees was filmed with a camera (green) through a dome lighting (grey). The specially designed hive (brown) was only 2.4 cm wide, so that the bees would raise young as quickly as possible (right). Credit: Paul Siefert/Bee Research Institute Oberursel/Goethe University Frankfurt

Figure. 2 Excerpts from the video of the development of a worker bee. Above left: The queen lays an egg (arrow) in the cell. The growing larva (arrow) is fed with jelly. Below left: the metamorphosis takes about one hour and includes the rupture of the larval skin (arrow); the pupa is beneath it. Finally, the adult bee hatches out of the cell. Credit: Paul Siefert/Bee Research Institute Oberursel/Goethe University Frankfurt

Further information:

Dr Paul Siefert
Bee Research Institute Oberursel
Subsidiary of the Polytechnical Society Frankfurt am Main,
Faculty of Biosciences
Goethe University Frankfurt am Main
Tel.: +49 6171 21278
siefert@bio.uni-frankfurt.de
www.institut-fuer-bienenkunde.de 

 

May 25 2020
10:42

Two research aircraft investigate reduced concentrations of pollutants in the air

BLUESKY scrutinizes the lockdown-altered atmosphere

FRANKFURT. The COVID-19 pandemic is not only affecting almost every aspect of our daily lives, but also the environment. A German team including atmosphere researchers around Prof. Joachim Curtius (Goethe University Frankfurt) now wants to find out how strong these effects are on the atmosphere. Over the next two weeks, as part of the BLUESKY research programme, the scientists led by the Max Planck Institute for Chemistry and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) will measure concentrations of trace gases and pollutants in the air over European urban areas and in the flight corridor to North America. The aim of these research missions is to investigate how reduced emissions from industry and transport are changing atmospheric chemistry and physics.

 A clear blue sky without condensation trails and empty streets – this is a typical situation during the Coronavirus lockdown. Traffic, particularly air transport, and industrial production have been reduced worldwide due to the COVID-19 pandemic. There are fewer aircraft in the air and vehicles on the road in Europe than before the pandemic. Air pollution has dropped by 20 to 40 percent, and daily emissions from aircraft have decreased by up to 85 percent. This means that the atmosphere is much less polluted with emissions from transport and industry.

A German research team now wants to make rapid use of this unusual situation for the BLUESKY project. Scientists from DLR, the Max Planck Institute for Chemistry, Goethe University Frankfurt, and the research centres at Jülich and Karlsruhe intend to use two DLR research aircraft to conduct a globally unique investigation into the resulting changes in Earth's atmosphere for the first time. DLR’s HALO and Falcon research aircraft have been equipped with highly specialised instrumentation and will fly over Germany, Italy, France, Great Britain and Ireland in the course of the next two weeks. They will also fly over the North Atlantic, along the flight corridor to North America.

“DLR is deploying part of its unique research aircraft fleet to exploit an almost unique opportunity. During these missions, the atmosphere will be analysed in a state that could be achieved in the future with sustainable management of human activities. We will observe how the environment changes with the ramp-up of industrial activities. This will give us an entirely new perspective on the anthropogenic influence on Earth’s atmosphere,” explains Rolf Henke, DLR Executive Board Member responsible for aeronautics research. “Together with our partners, we are making a significant contribution to redefining humankind’s activities once the pandemic is under control.”

Coordinated research flights with two measurement aircraft

Jos Lelieveld, Director of the Max Planck Institute for Chemistry, wants to use the BLUESKY missions to clarify whether there is a correlation between the clear blue sky during the lockdown and the prevalence of aerosol particles in the atmosphere. “The unique blue sky of recent weeks cannot be explained by meteorological conditions and the decrease in emissions near the ground. Aircraft may have a greater impact on the formation of aerosol particles than previously thought,” says the atmospheric researcher, who is the Scientific Director of the HALO flights. Aerosols, microscopic particles in the air that also influence cloud formation, are finely distributed. They scatter and absorb solar radiation and thus also have an impact on the climate, because they influence the radiation balance of the atmosphere. Aerosols are created, amongst other ways, during the combustion of fossil fuels.

Christiane Voigt, Head of the Cloud Physics Department at the DLR Institute of Atmospheric Physics and Scientific Director of the Falcon flights, also sees a unique opportunity with BLUESKY. “The current state of the atmosphere represents a kind of ‘zero point’ for science. We will be able to measure a reference atmosphere that is only slightly polluted with emissions from industry and transport, including aviation. This gives us a unique opportunity to better understand the effects of the anthropogenic emissions prior to the shutdown.” The atmospheric physicist emphasises that, only through the cooperation of all the partners, was it possible to plan and implement the scientifically and logistically highly complex missions at very short notice.

Emissions from air transport, industry and road traffic in urban areas

Voigt and her colleagues believe that the BLUESKY data will provide a clearer picture of anthropogenic influences on the composition of Earth’s atmosphere. With the equipment on board both research aircraft, the BLUESKY scientists are investigating aircraft emissions such as nitrogen oxides, sulphur dioxide and aerosols at cruising altitude, in addition to the few remaining contrails. Among other things, they want to find out how much these emissions have decreased over Europe and the North Atlantic flight corridor. Approximately 30,000 aircraft fly over Europe every day, with correspondingly significant emissions. The reduced air traffic will allow more flexible flight routes for the measurements.

In addition, the researchers want to investigate the reduced emission plumes from urban areas and clarify how emissions are distributed at the atmospheric boundary layer. For example, the BLUESKY scientists plan to fly over the Ruhr area and the regions around Frankfurt am Main, Berlin and Munich. Flights over the Po Valley in Italy and around Paris and London are also planned. “Close to cities and conurbations, we will approach the atmospheric boundary layer at an altitude of one to two kilometres, since emissions from road traffic and industry are concentrated there,” explains Jos Lelieveld. “We are interested in how much the concentrations of sulphur dioxide, nitrogen oxides, hydrocarbons and their chemical reaction products, as well as ozone and aerosols, have changed.” He is also very proud that the team is the first in the world to implement a measurement campaign of this type.

Rapid preparations for flights – with special infection control rules

In recent weeks, two DLR research aircraft –measuring the Falcon 20E and the Gulfstream G550 HALO – have been successfully converted at short notice for the BLUESKY missions. The conversions were carried out at the DLR Flight Operations Facility in Oberpfaffenhofen. “Numerous instruments have had to be installed and adapted, and the aircraft modified for the upcoming missions,” says Burkard Wigger, Head of DLR Flight Experiments. “Close cooperation between the various scientific organisations has made it possible for these two research aircraft to operate simultaneously under the challenging conditions resulting from the Coronavirus pandemic.”

The preparation, execution and follow-up of the flights is being carried out in accordance with the current rules regarding personal interactions and infection control. Joint flights by Falcon and HALO are planned until the first half of June. The evaluation of the data and the analysis of the results will then take several months. The analysis will include comparative data from previous HALO research flight campaigns on air traffic emissions and emissions from major cities and conurbations.

About HALO: The High Altitude and Long Range (HALO) research aircraft is a joint initiative of German environmental and climate research institutions. HALO is supported by grants from the Federal Ministry of Education and Research (BMBF), the German Research Foundation (DFG), the Helmholtz Association of German Research Centres, the Max Planck Society (MPG), the Leibniz Association, the Free State of Bavaria, the Karlsruhe Institute of Technology (KIT), the Forschungszentrum Jülich and the German Aerospace Center (DLR).

More information: Prof. Joachim Curtius, Institute for Atmospheric and Environmental Sciences, Goethe University Frankfurt, Phone: +49 (0)69 798-40258, curtius@iau.uni-frankfurt.de

 

May 14 2020
13:52

International research project observes ultrafast particle growth through ammonia and nitric acid 

How particulate matter arises from pollutant gases 

FRANKFURT. When winter smog takes over Asian mega-cities, more particulate matter is measured in the streets than expected. An international team, including researchers from Goethe University Frankfurt, as well as the universities in Vienna and Innsbruck, has now discovered that nitric acid and ammonia in particular contribute to the formation of additional particulate matter. Nitric acid and ammonia arise in city centres predominantly from car exhaust. Experiments show that the high local concentration of the vapours in narrow and enclosed city streets accelerates the growth of tiny nanoparticles into stabile aerosol particles (Nature, DOI 10.1038/s41586-020-2270-4).

In crowded urban centres, high concentrations of particulate matter cause considerable health effects. Especially in winter months, the situation in many Asian mega-cities is dramatic when smog significantly reduces visibility and breathing becomes difficult.

Particulates, with a diameter of less than 2.5 micrometres, mostly form directly through combustion processes, for example in cars or heaters. These are called primary particulates. Particulates also form in the air as secondary particulates, when gases from organic substances, sulphuric acid, nitric acid or ammonia, condense on tiny nanoparticles. These grow into particles that make up a part of particulate matter.

Until now, how secondary particulates could be newly formed in the narrow streets of mega-cities was a puzzle. According to calculations, the tiny nanoparticles should accumulate on the abundantly available larger particles rather than forming new particulates.

Scientists in the international research project CLOUD have now recreated the conditions that prevail in the streets of mega-cities in a climate chamber at the particle accelerator CERN in Geneva, and reconstructed the formation of secondary particulates: in the narrow and enclosed streets of a city, a local increase of pollutants occurs. The cause of the irregular distribution of the pollutants is due in part to the high pollutant emissions at the street level.  Furthermore, it takes a while before the street air mixes with the surrounding air. This leads to the two pollutants ammonia and nitric acid being temporarily concentrated in the street air. As the CLOUD experiments demonstrate, this high concentration creates conditions in which the two pollutants can condense onto nanoparticles: ammonium nitrate forms on condensation cores the size of only a few nanometres, causing these particles to grow rapidly.

“We have observed that these nanoparticles grow rapidly within just a few minutes. Some of them grow one hundred times more quickly than we had previously ever seen with other pollutants, such as sulphuric acid," explains climate researcher Professor Joachim Curtius from Goethe University Frankfurt. “In crowded urban centres, the process we observed therefore makes an important contribution to the formation of particulate matter in winter smog – because this process only takes place at temperatures below about 5 degrees Celsius." The aerosol physicist Paul Winkler from the University of Vienna adds: “When conditions are warmer, the particles are too volatile to contribute to growth."

The formation of aerosol particles from ammonia and nitric acid probably takes place not only in cities and crowded areas, but on occasion also in higher atmospheric altitudes. Ammonia, which is primarily emitted from animal husbandry and other agriculture, arrives in the upper troposphere from air parcels rising from close to the ground by deep convection, and lightning creates nitric acid out of nitrogen in the air. “At the prevailing low temperatures there, new ammonium nitrate particles are formed which as condensation seeds play a role in cloud formation," explains ion physicist Armin Hansel from the University of Innsbruck, pointing out the relevance of the research findings for climate.

The experiment CLOUD (Cosmics Leaving OUtdoor Droplets) at CERN studies how new aerosol particles are formed in the atmosphere out of precursor gases and continue to grow into condensation seeds. CLOUD thereby provides fundamental understanding on the formation of clouds and particulate matter. CLOUD is carried out by an international consortium consisting of 21 institutions. The CLOUD measuring chamber was developed with CERN know-how and achieves very precisely defined measuring conditions. CLOUD experiments use a variety of different measuring instruments to characterise the physical and chemical conditions of the atmosphere consisting of particles and gases. In the CLOUD project, the team led by Joachim Curtius from the Institute for Atmosphere and Environment at Goethe University Frankfurt develops and operates two mass spectrometers to detect trace gases such as ammonia and sulphuric acid even at the smallest concentrations as part of projects funded by the BMBF and the EU. At the Faculty of Physics at the University of Vienna, the team led by Paul Winkler is developing a new particle measuring device as part of an ERC project. The device will enable the quantitative investigation of aerosol dynamics specifically in the relevant size range of 1 to 10 nanometres. Armin Hansel from the Institute for Ion Physics and Applied Physics at the University of Innsbruck developed a new measuring procedure (PTR3-TOF-MS) to enable an even more sensitive analysis of trace gases in the CLOUD experiment with his research team as part of an FFG project.

Publication: Wang, M., Kong, W., et al. Rapid growth of new atmospheric particles by nitric acid and ammonia condensation. Nature, DOI 10.1038/s41586-020-2270-4.

Further information: Prof. Dr. Joachim Curtius, Institute for Atmosphere and Environment, Goethe University Frankfurt am Main, Tel: +49 69 798-40258, email: curtius@iau.uni-frankfurt.de

Prof. Dr. Armin Hansel, Institute for Ion Physics and Applied Physics, University of Innsbruck, Tel.: +43 512 507 52640, email: armin.hansel@uibk.ac.at

Prof. Dr. Paul Winkler, Aerosol physics and Environmental Physics, Faculty for Physics, University of Vienna, Tel: +43-1-4277-734 03, email: paul.winkler@univie.ac.at

 

May 14 2020
13:40

Cell culture model: several compounds stop SARS-CoV-2 virus

Frankfurt researchers discover potential targets for COVID-19 therapy 

FRANKFURT. A team of biochemists and virologists at Goethe University and the Frankfurt University Hospital were able to observe how human cells change upon infection with SARS-CoV-2, the virus causing COVID-19 in people. The scientists tested a series of compounds in laboratory models and found some which slowed down or stopped virus reproduction. These results now enable the search for an active substance to be narrowed down to a small number of already approved drugs. (Nature DOI: 10.1038/s41586-020-2332-7). Based on these findings, a US company reports that it is preparing clinical trials. A Canadian company is also starting a clinical study with a different substance.  

Since the start of February, the Medical Virology of the Frankfurt University Hospital has been in possession of a SARS-CoV-2 infection cell culture system. The Frankfurt scientists in Professor Sandra Ciesek's team succeeded in cultivating the virus in colon cells from swabs taken from two infected individuals returning from Wuhan (Hoehl et al. NEJM 2020).

Using a technique developed at the Institute for Biochemistry II at Goethe University Frankfurt, researchers from both institutions were together able to show how a SARS-CoV-2 infection changes the human host cells. The scientists used a particular form of mass spectrometry called the mePROD method, which they had developed only a few months previously. This method makes it possible to determine the amount and synthesis rate of thousands of proteins within a cell.

The findings paint a picture of the progression of a SARS-CoV-2 infection: whilst many viruses shut down the host's protein production to the benefit of viral proteins, SARS-CoV-2 only slightly influences the protein production of the host cell, with the viral proteins appearing to be produced in competition to host cell proteins. Instead, a SARS-CoV-2 infection leads to an increased protein synthesis machinery in the cell. The researchers suspected this was a weak spot of the virus and were indeed able to significantly reduce virus reproduction using something known as translation inhibitors, which shut down protein production.

Twenty-four hours after infection, the virus causes distinct changes to the composition of the host proteome: while cholesterol metabolism is reduced, activities in carbohydrate metabolism and in modification of RNA as protein precursors increase. In line with this, the scientists were successful in stopping virus reproduction in cultivated cells by applying inhibitors of these processes. Similar success was achieved by using a substance that inhibits the production of building blocks for the viral genome.

The findings have already created a stir on the other side of the Atlantic: in keeping with common practise since the beginning of the corona crisis, the Frankfurt researchers made these findings immediately available on a preprint server and on the website of the Institute for Biochemistry II (http://pqc.biochem2.de#coronavirus). Professor Ivan Dikic, Director of the Institute, comments: “Both the culture of 'open science', in which we share our scientific findings as quickly as possible, and the interdisciplinary collaboration between biochemists and virologists contributed to this success. This project started not even three months ago, and has already revealed new therapeutic approaches to COVID-19."

Professor Sandra Ciesek, Director of the Institute for Medical Virology at the University Hospital Frankfurt, explains: “In a unique situation like this we also have to take new paths in research. An already existing cooperation between the Cinatl and Münch laboratories made it possible to quickly focus the research on SARS-CoV-2. The findings so far are a wonderful affirmation of this approach of cross-disciplinary collaborations."

Among the substances that stopped viral reproduction in the cell culture system was 2-Deoxy-D-Glucose (2-DG), which interferes directly with the carbohydrate metabolism necessary for viral reproduction. The US company Moleculin Biotech possesses a substance called WP1122, a prodrug similar to 2-DG. Recently, Moleculin Biotech announced that they are preparing a clinical trial with this substance based on the results from Frankfurt.  https://www.moleculin.com/covid-19/.

Based on another one of the substances tested in Frankfurt, Ribavirin, the Canadian company Bausch Health Americas is starting a clinical study with 50 participants: https://clinicaltrials.gov/ct2/show/NCT04356677?term=04356677&draw=2&rank=1

Dr Christian Münch, Head of the Protein Quality Control Group at the Institute for Biochemistry II and lead author, comments: “Thanks to the mePROD-technology we developed, we were for the first time able to trace the cellular changes upon infection over time and with high detail in our laboratory. We were obviously aware of the potential scope of our findings. However, they are based on a cell culture system and require further testing. The fact that our findings may now immediately trigger further in vivo studies with the purpose of drug development is definitely a great stroke of luck." Beyond this, there are also other potentially interesting candidates among the inhibitors tested, says Münch, some of which have already been approved for other indications.

Professor Jindrich Cinatl from the Institute of Medical Virology and lead author explains: “The successful use of substances that are components of already approved drugs to combat SARS-CoV-2 is a great opportunity in the fight against the virus. These substances are already well characterised, and we know how they are tolerated by patients. This is why there is currently a global search for these types of substances. In the race against time, our work can now make an important contribution as to which directions promise the fastest success."

Publication: SARS-CoV-2 infected host cell proteomics reveal potential therapy targets. Denisa Bojkova, Kevin Klann, Benjamin Koch, Marek Widera, David Krause, Sandra Ciesek, Jindrich Cinatl, Christian Münch. Nature DOI: 10.1038/s41586-020-2332-7,  https://www.nature.com/articles/s41586-020-2332-7 (active starting 10am London time (BST), 5am US Eastern Time)

Images may be downloaded here: http://www.uni-frankfurt.de/88340061
Captions: Dr. Christian Münch (Credit: Uwe Dettmar for Goethe University Frankfurt)
Prof. Dr. rer. nat. Jindrich Cinatl (Credit: University Hospital Frankfurt)

More about the mePROD method: Biochemistry researchers at Goethe University develop a new proteomics procedure https://aktuelles.uni-frankfurt.de/englisch/biochemistry-researchers-at-goethe-university-develop-new-protoeomics-procedure/

Further information:
Professor Dr. rer. nat. Jindrich Cinatl, Head of the Research Group Cinatl, Institute for Medical Virology, University Hospital Frankfurt am Main, Tel. +49  69 6301-6409, E-mail: cinatl@em.uni-frankfurt.de,
Homepage: https://www.kgu.de/einrichtungen/institute/zentrum-der-hygiene/medizinische-virologie/forschung/research-group-cinatl/

Dr. Christian Münch, Head of the Group Protein Quality Control, Institute for Biochemistry II, Goethe University Frankfurt am Main Tel: +49 69 6301 6599, E-Mail: ch.muench@em.uni-frankfurt.de,
Homepage: https://www.biochem2.com/index.php/22-ibcii/pqc/130-frontpage-pqc

 

May 6 2020
13:53

Heat-loving bacteria use various tiny surface hairs for movement and DNA reception

Division of labour on the surface of bacteria

FRANKFURT. Bacteria of the species Thermus thermophilus possess two types of extensions on their surface (pili) for the purpose of motion and for capturing and absorbing DNA from their environment. This has been discovered by researchers at Goethe University together with researchers in Great Britain. The discovery of the motion pilus helps to better understand the functionality of the DNA-capturing pilus functions. (Nature Communications, DOI 10.1038/s41467-020-15650-w)

The bacteria Thermus thermophilus likes it hot. It was first discovered in the hot springs at Izu in Japan, where it thrives at an optimal temperature of about 65 degrees Celsius. Like all bacteria, Thermus thermophilus has developed mechanisms to adjust to changing environmental conditions. The bacteria changes its genetic material by exchanging DNA with other bacteria, or absorbing DNA fragments from its environment. These might come from dead bacteria cells, plants or animals. The bacteria incorporate the DNA fragments into their genetic material and keep it if the DNA proves useful.

Microbiologists at Goethe University led by Professor Beate Averhoff from the Molecular Microbiology & Bioenergetics of the Department of Molecular Biosciences together with a team of scientists led by Dr Vicky Gold from the “Living Systems" Institute of the University of Exeter in Great Britain have now studied the tiny hairs (called pili) on the surface of the Thermus bacteria. The scientists discovered that there are two types of pili with different functions. High-resolution electron microscope images from Great Britain allow thick and thin pili to be distinguished, and the Frankfurt scientists used biochemical and molecular biological methods to demonstrate that the thick pili are for DNA capture, and the thin pili for moving on surfaces.

“We want to find out exactly how Thermus thermophilus absorbs DNA from its environment using its pili, as the precise mechanism is unknown," explains Professor Beate Averhoff from the Institute for Molecular Biosciences at Goethe University. “Through our most recent investigations we have learned that Thermus bacteria have distinct pili for motion. Therefore, the thick pili possibly serve the purpose of DNA absorption, which demonstrates how important this process is for the bacteria. In our structure analyses we also found an area on the thick pili where DNA could bind."

The interplay of electron microscopy and molecular biology also allowed the scientists to better understand the mechanics of the pili. For both motion and DNA absorption, pili have to be dynamic, i.e., able to be extended and retracted. “For the first time, the high resolution structure of both pili gave us insights not only into the structure of the pili, but also into the dynamics," Averhoff explains.

Since pili are widespread and in pathogenic bacteria are also responsible for attaching to the host, this may lead to new points of attack for preventing infectious processes.

Publication: Alexander Neuhaus, Muniyandi Selvaraj, Ralf Salzer, Julian D. Langer, Kerstin Kruse, Lennart Kirchner, Kelly Sanders, Bertram Daum, Beate Averhoff, Vicki A. M. Gold (2020). Cryo-electron microscopy reveals two distinct type-IV pili assembled by the same bacterium. Nature Communications, https://doi.org/10.1038/s41467-020-15650-w )

An image may be downloaded here:  http://www.uni-frankfurt.de/88063448

Caption: Bacteria of the species Thermus thermophilus possess different tiny hairs (pili) which are used either to capture DNA or for motion. This has been discovered by scientists at Goethe University Frankfurt and the University of Exeter. Graphic: aduka, Agency Frankfurt am Main(www.aduka.de) for Goethe University Frankfurt.

Further information: Prof. Beate Averhoff, Molecular Microbiology and Bioenergetics. Tel.: +49 69 798-29509, averhoff@bio.uni-frankfurt.dehttps://www.mikrobiologie-frankfurt.de