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Researchers at Goethe University are studying the auditory perception of bats
Whenever bats use echolocation when
foraging for food or to communicate with other bats: sounds are omnipresent.
How Seba's short-tailed bat, a species native to South America, filters out
important signals from the wide diversity of ambient sound is being examined by
researchers at the Institute of Cell Biology and Neuroscience at Goethe
University Frankfurt. The most recent finding: the brain stem, which to date
had been regarded as being solely responsible for very basic tasks, already
processes the probabilities of acoustic signals.
FRANKFURT. Bats
are renowned for their echolocation skills, navigation using sound therefore:
they 'see' with their extremely sensitive hearing, by emitting ultrasonic calls
and forming a picture of their immediate environment on the basis of the
reflected sound. Thus, for instance, Seba's short-tailed bat (Carollia perspicillata) finds the fruit
it prefers to eat using this echolocation system. At the same time bats use
their voice to communicate with other bats, whereby they then utilise a
somewhat lower frequency range. Seba's short-tailed bat has a vocal range which
is otherwise only found among songbirds and humans. Just like humans it creates
sound via its larynx.
In order to find out how Seba's
short-tailed bat filters out particularly important signals from the wide
diversity of different sounds – warning cries from other bats, the isolation
calls of infant bats, as well as the reflections from pepper plants in the
labyrinth of leaves and branches, for example – researchers at Goethe
University Frankfurt recorded the brain waves of the bats.
To this end the researchers headed by
Professor Manfred Kössl from the Institute of Cell Biology and Neuroscience
inserted electrodes – as fine as acupuncture needles – under the scalp of the
bats while the bats drowsed under anaesthetic. Ultimately this measuring method
is so sensitive that even the slightest movement of a bat's head would
interfere with the results of the measurements. Despite being anaesthetised,
the bat's brain still reacts to sound.
Successions of two notes with differing
pitches, corresponding to either echolocation calls or communication calls,
were then played back to the bats. Initially a sequence was played back in
which note 1 occurs much more frequently than note 2, for example
“1-1-1-1-2-1-1-1-2-1-1-1-1-1-1...". This was reversed in the next sequence,
with note 1 occurring rarely and note 2 frequently. In this manner the scientists
wanted to establish whether the neuronal processing of a given sound depended
on the probability of it occurring and not, for instance, on its pitch.
Ph.D. student Johannes Wetekam, lead
author of the study, explains: “Indeed our research results show that a rare
and thus unexpected sound leads to a stronger neuronal response than a frequent
sound." In this respect the bat's brain regulates the strength of the neuronal
response to frequent echolocation calls by downplaying these, and amplifies the
response to infrequent communication calls. Wetekam: “This shows that the bats
process unexpected sounds differently in dependence on their frequency in order
to gather adequate sensory impressions."
The interesting aspect here, says Wetekam,
is that the processing of the signals seemingly already occurs in the brain
stem, which it has been assumed to date merely receives acoustic signals and
transmits them to higher regions of the brain, where the signals are then
offset against one another. The reason: “This probably saves the brain as a
whole a lot of energy and allows for a very fast reaction," says Wetekam.
Professor Manfred Kössl believes: “We are
all familiar with the party effect: we filter out the conversations of people
in our immediate environment so we can concentrate totally on the person we are
speaking with. These mechanisms are similar to those found in bats. If we can
better understand how bats hear sound, in the future this could help us to
understand what occurs with disorders such as ADHD (attention deficit
hyperactivity disorder), which disrupt adequate processing of extraneous
stimuli."
Publication: Johannes
Wetekam, Julio Hechavarría, Luciana López-Jury, Manfred Kössl: Correlates of deviance detection in
auditory brainstem responses of bats. Eur. J. Neurosci 2021, Nov 11 https://onlinelibrary.wiley.com/doi/10.1111/ejn.15527
Picture
download: https://www.uni-frankfurt.de/112837573
Caption:
Searching for fruit at night: Seba's short-tailed bat (Carollia perspicillata). Photo: Julio
Hechavarría
Further
Information:
Johannes Wetekam
Department of Neurobiology and
Biosensors
Phone +49 (0)69 798 42066
wetekam@bio.uni-frankfurt.de
Professor Manfred Kössl
Institute of Cell Biology and Neuroscience
Head of Department of Neurobiology and Biosensors
Goethe University Frankfurt, Germany
Phone. +49 (0)69 798 42052
Koessl@bio.uni-frankfurt.de
https://www.goethe-university-frankfurt.de/47091958/Department_of_Neurobiology_and_Biosensors
Editor: Dr. Markus Bernards, Science Editor, PR & Communication Office, Tel: +49 (0) 69 798-12498, Fax: +49 (0) 69 798-763 12531, bernards@em.uni-frankfurt.de.
Green chemistry needs more green toxicology
With the early assessment of sustainable, newly developed chemicals and products it is possible to assess a potential risk of toxic substances being released at a later point in product cascades. This has been revealed in a proof-of-concept study jointly coordinated by Goethe University Frankfurt and RWTH Aachen University. In the course of the study the toxicity of sustainable biosurfactants, potentially applied in, e.g., bio-shampoos, and of a new technology for the economical deployment of plant protection agents were analysed using a combination of computer modelling and laboratory experiments. The study is the first step towards a safe bioeconomy from an eco-toxicological stance, and which uses sustainable resources and processes to reduce environmental burdens significantly.
FRANKFURT. The
natural resources of the planet are running short, yet at the same time they
are the basis for our prosperity and development. A dilemma which the EU intends
to overcome with the aid of its revised bioeconomy strategy.
Rather than relying on fossil-based materials, the economy is to be based on
renewable materials. These include plants, wood, microorganisms and algae. At
some point in time everything is to be found in closed loops, yet the
implementation of a circular bioeconomy requires a shift in the manufacture of chemicals.
These also have to be produced from bio-materials rather than crude oil. Based
on these requirements the American chemists Paul Anastas and John C. Warner formulated
their twelve principles of green chemistry in 1998. One of their principles has
very much been neglected to date, however: the reduction of the environmental
toxicity of newly developed substances.
It is precisely here that the interdisciplinary
project “GreenToxiConomy", which is part of the scientific
alliance Bioeconomy Science Center (BioSC), comes into play. The objective
was to examine bio-based substances and innovative technologies with a view to
their toxic impact on the environment at an early stage in product development
and to incorporate the resulting findings into product design. Project partners
from Aachen, Jülich and Düsseldorf provided two of their bio-based product
candidates for the analyses: microgel containers for crop protection agents and
biosurfactants.
The wash-active biosurfactants for use in
shampoos and detergents at BioSC are based on the synthesis
abilities of the Pseudomonas putida bacterium and the Ustilago maydis fungus,
respectively, rather than on crude oil. The microgel technology allows for the
controlled delivery of crop protection agents because the containers ensure
that the active ingredients still adhere to the plants in the event of rain.
Dr. Sarah Johann, the lead author for the
study and the head of a working group in the department of evolutionary ecology
and environmental toxicology at the Institute for Ecology, Evolution and
Diversity at Goethe University Frankfurt, explains: “For the analysis of novel
substances and technologies we have selected a broad range of concentration to
be able to adequately estimate potential hazards for humans and the environment.
We wanted to examine whether the bio-based surfactants were more environmentally
friendly than conventional chemical surfactants. In addition, we investigated
whether the microgel containers per se induce any toxicity."
To ensure the ecotoxicological evaluation
was as precise as possible, the project team combined two elements in the
determination of the toxicity: computer-aided prognoses (in silico) and experiments in the laboratory (in vitro and in vivo). The
computer models work with the toxicity data of known chemicals, whose structure
they compared with the structure of the new bio-based substances to forecast the
toxicity. The experiments were conducted on aquatic
and terrestrial organisms that represent specific organism groups, among them
earthworms, springtails, water fleas and zebrafish embryos at a very early
stage.
The result: both biosurfactants and microgels
are highly promising candidates for use in a future bioeconomy whose products must
be sustainably manufactured while not causing any environmental damage or harm
to humans both during and after their utilisation. “We can only make statements
within certain limits, however, as the transfer of laboratory results to the
reality in the open field or in other applications is complicated," says
Johann. More research is necessary for a holistic assessment of the risk potential,
which is why follow-up projects are planned.
Prof. Henner Hollert, head of the evolutionary
ecology and environmental toxicology department at Goethe University Frankfurt,
underlines the significance of the close interdisciplinary collaboration on
“GreenToxiConomy". In the project biotechnologists and engineers jointly
designed a new product, and this was evaluated during the development stages by
eco-toxicologists from Goethe University together with a team at RWTH Aachen headed
by Prof. Dr. Martina Roß-Nickoll. “This continuous process is the major
strength of the project." Although it is only a first step towards a bioeconomy
that is safe in eco-toxicological terms, for Hollert it is already clear that
eco-toxicology and green toxicology will play a key role in the plans being
drawn up by the EU. “Whenever it is a question of future bio-based product
development and product design, we have to clarify the consequences for humans
and the environment at an early stage. In this respect our approach can provide
valuable results."
Publication:
Sarah Johann, Fabian G. Weichert, Lukas
Schröer, Lucas Stratemann, Christoph Kämpfer, Thomas-Benjamin Seiler, Sebastian
Heger, Alexander Töpel, Tim Sassmann, Andrij Pich, Felix Jakob, Ulrich
Schwaneberg, Peter Stoffels, Magnus Philipp, Marius Terfrüchte, Anita
Loeschcke, Kerstin Schipper, Michael Feldbrügge, Nina Ihling, Jochen Büchs,
Isabel Bator, Till Tiso, Lars M. Blank, Martina Roß-Nickoll, Henner Hollert. A
plea for the integration of Green Toxicology in sustainable bioeconomy
strategies – Biosurfactants and microgel-based pesticide release systems as
examples. In: J. Hazard. Mat. 426 (2022) 127800. https://doi.org/10.1016/j.jhazmat.2021.127800
Further
Information:
Prof. Dr. Henner Hollert
Institute of Ecology, Diversity and Evolution
Goethe University Frankfurt
Phone: +49 (0)69 798-42171
hollert@bio.uni-frankfurt.de
https://www.bio.uni-frankfurt.de/43970666/Abt__Hollert
Nationwide longitudinal study in Germany investigated 250 million hospital admissions
In Germany, liver cirrhosis has the highest mortality rate of any chronic disease requiring hospital admission. When diagnosed as a comorbidity of other chronic diseases, liver cirrhosis at least doubles the mortality rate. Overall, the number of patients hospitalised with liver cirrhosis has increased throughout Germany despite the introduction of very effective drugs for treating hepatitis C, and alcohol abuse remains by far the most common cause. These are the results of a study headed by Prof. Jonel Trebicka at the University Hospital Frankfurt, which observed patients over a period of 14 years.
FRANKFURT. Cirrhosis, a
disease of the liver in which tissue becomes dysfunctional and scarred, is the final
stage of most chronic liver diseases and the fourth most frequent cause of
death in central Europe. However, until now hardly any current findings have been
available on its epidemiological profile in Germany. For this reason, Prof.
Jonel Trebicka and his team of researchers investigated the data sets from the German
Federal Statistical Office on the approx. 250 million hospital admissions
taking place from 2005 to 2018 in Germany for any reason, and categorised them
according to the Tenth Revision of the International Classification of Diseases
(ICD-10). They found that 0.94 per cent of these hospitalised patients had been
diagnosed with cirrhosis of the liver, which in the majority of cases occurred
as a comorbidity and not the primary disease. In absolute figures, admissions of
patients with liver cirrhosis rose from 151,108 to 181,688 during the observation
period.
The primary end point of the study was the mortality
rate from liver cirrhosis in hospital. This did indeed exhibit a welcome fall from
11.57% to 9.49% during the investigation period, but it is still much higher
than the respective rates for other chronic diseases such as cardiac
insufficiency (8.4%), renal failure (6.4%) and chronic obstructive pulmonary
disease (5.2%). In cases where liver cirrhosis was comorbid with another chronic
disease, it increased that disease's mortality rate two to three fold; the
greatest effect was observed with infectious respiratory
diseases.
Thanks to the introduction of direct-acting antivirals
to combat Hepatitis C, the proportion of HCV-related cirrhosis fell during the
observation period to around one third. On the other hand, the frequency of cirrhosis
caused by non-alcoholic fatty liver disease quadrupled during the same period, in
parallel with a rise in the number of obese patients. However, despite these etiological trends, cirrhosis caused by alcohol abuse
continues to dominate. It accounts for 52 per cent of all cirrhoses in the study, and the absolute number is still rising.
Gastrointestinal bleeding is becoming increasingly rare
as a complication of liver cirrhosis in hospital patients, presumably due to
the treatment guidelines that continue to be applied in German hospitals,
including endoscopic procedures or the administration of non-selective beta
blockers. By 2018, bleeding from oesophageal varices had shrunk to one tenth of
its original level in 2005. On the other hand, deterioration of symptoms owing to
ascites or hepatic encephalopathy caused by insufficient detoxification by the liver has
increased. The number of portal vein thromboses doubled in parallel with the intensified
use of imaging diagnostics.
The patients admitted with cirrhosis were much younger
than those with other chronic diseases: half of them were under the age of 64. Higher
hospitalisation rates and in-hospital mortality rates were recorded in the eastern
German states than in western Germany. Across the country, around two thirds of
patients hospitalised with liver cirrhosis were men. Many of them died while in
their fifties or younger, which explains the large number of disability-adjusted
life years and the enormous socio-economic burden caused by liver cirrhosis, as
men in this age group still account for the majority of the labour force.
“The results of our study show that the
decision-makers and financing bodies in the health system should invest much
more in the prevention of alcohol-related liver cirrhosis," Prof. Jonel
Trebicka concludes. “They also point up how important it is to recognise and treat liver cirrhosis as a comorbidity of other chronic
diseases."
Publication:
Wenyi Gu, Hannah Hortlik, Hans-Peter
Erasmus, Louisa Schaaf, Yasmin Zeleke, Frank E. Uschner, Philip Ferstl, Martin
Schulz, Kai-Henrik Peiffer, Alexander Queck, Tilman Sauerbruch, Maximilian
Joseph Brol, Gernot Rohde, Cristina Sanchez, Richard Moreau, Vicente Arroyo,
Stefan Zeuzem, Christoph Welsch, Jonel Trebicka: Trends and the course of liver cirrhosis and its complications in
Germany: Nationwide population-based study (2005 to 2018) The
Lancet Regional Health - Europe 2022;12: 100240 https://doi.org/10.1016/j.lanepe.2021.100240
International research team examines photoelectric effect with the aid of a COLTRIMS reaction microscope
When light hits a material, electrons can be released from this material – the photoelectric effect. Although this effect played a major role in the development of the quantum theory, it still holds a number of secrets: To date it has not been clear how quickly the electron is released after the photon is absorbed. Jonas Rist, a Ph.D. student working within an international team of researchers at the Institute for Nuclear Physics at Goethe University Frankfurt, has now been able to find an answer to this mystery with the aid of a COLTRIMS reaction microscope which had been developed in Frankfurt: The emission takes place lightning fast, namely within just a few attoseconds – within a billionths of billionths of a second.
FRANKFURT. It is
now exactly one hundred years ago that Albert Einstein was awarded the Nobel
Prize in Physics for his work on the photoelectric effect.
The jury had not yet really understood his revolutionary theory of relativity –
but Einstein had also conducted ground-breaking work on the photoelectric effect.
With his analysis he was able to demonstrate that light comprises individual
packets of energy – so-called photons. This was the decisive confirmation of Max
Planck's hypothesis that light is made up of quanta, and paved the way for the modern
quantum theory.
Although the photoelectric effect in molecules
has been studied extensively in the meantime, it has not yet been possible to
determine its evolution over time in an experimental measurement. How long does
it take after a light quantum has hit a molecule for an electron
to be dislodged in a specific direction? “The length of time between photon
absorption and electron emission is very difficult to measure because it is
only a matter of attoseconds," explains Till Jahnke, the PhD-supervisor of Jonas
Rist. This corresponds to just a few light oscillations. “It has so far been
impossible to measure this duration directly, which is why we have now
determined it indirectly." To this end the scientists used a COLTRIMS reaction
microscope – a measuring device with which individual atoms and molecules can
be studied in incredible detail.
The researchers fired extremely intense
X-ray light – generated by the synchrotron radiation source BESSY II of
Helmholtz-Zentrum Berlin – at a sample of carbon monoxide in the centre of the reaction microscope. The carbon monoxide molecule consists
of one oxygen atom and one carbon atom. The X-ray beam now had exactly the
right amount of energy to dislodge one of the electrons from the innermost electron
shell of the carbon atom. As a result, the molecule fragments. The oxygen and carbon
atoms as well as the released electron were then measured.
“And this is where quantum physics comes
into play," explains Rist. “The emission of the electrons
does not take place symmetrically in all directions." As carbon monoxide molecules have an outstanding axis, the
emitted electrons, as long as they are still in the immediate vicinity of the molecule,
are still affected by its electrostatic fields. This delays the release slightly
– and to differing extents depending upon the direction in which the electrons
are ejected.
As, in accordance with the laws of quantum
physics, electrons not only have a particle character but also a wave character,
which in the end manifests in form of an interference pattern on the detector.
“On the basis of these interference effects, which we were able to measure with
the reaction microscope, the duration of the delay could be determined indirectly
with very high accuracy, even if the time interval is incredibly short," says
Rist. “To do this, however, we had to avail of several of the possible tricks
offered by quantum physics."
On the one hand the measurements
showed that it does indeed only take a few dozen attoseconds to emit the electron.
On the other hand, they revealed that this time interval is very heavily
dependent on the direction in which the electron leaves the molecule, and that
this emission time is likewise greatly dependent on the velocity of the electron.
These measurements are not only
interesting for fundamental research in the field of physics. The models which
are used to describe this type of electron dynamics are also relevant for many chemical
processes in which electrons are not released entirely, but are transferred to
neighbouring molecules, for instance, and trigger further reactions there. “In
the future such experiments could also help to better understand chemical
reaction dynamics therefore," says Jahnke.
Publication:
Jonas Rist, Kim Klyssek, Nikolay M.
Novikovskiy, Max Kircher, Isabel Vela-Pérez, Daniel Trabert, Sven Grundmann,
Dimitrios Tsitsonis, Juliane Siebert, Angelina Geyer, Niklas Melzer, Christian
Schwarz, Nils Anders, Leon Kaiser, Kilian Fehre, Alexander Hartung, Sebastian
Eckart, Lothar Ph. H. Schmidt,1 Markus S. Schöffler, Vernon T. Davis, Joshua B.
Williams, Florian Trinter, Reinhard Dörner,1 Philipp V. Demekhin, Till Jahnke: Measuring the photoelectron emission delay
in the molecular frame. Nat Commun 12, 6657 (2021). https://doi.org/10.1038/s41467-021-26994-2
Picture
download:
https://www.uni-frankfurt.de/112731392
Captions:
COLTRIMS_atBESSYii_PhotoMiriamKeller.jpg:
High-tech:
COLTRIMS reaction microscope at electron storage ring BESSY II,
Helmholtz-Zentrum Berlin für Materialien und Energie (HZB). Photo: Miriam Weller, Goethe University Frankfurt
Rist_Jonas_PhotoAlexanderHartung.jpg:
Ph.D.
student Jonas Rist, Goethe University Frankfurt. Photo: Alexander Hartung, Goethe University Frankfurt
Further
Information:
Prof. Dr. Till Jahnke
European XFEL and
Institute for Nuclear Physics, Goethe University Frankfurt, Germany
Tel.: + 49 (0)69-798 47023 (Office)
till.jahnke@xfel.eu
Prof. Dr. Reinhard Dörner
Institute for Nuclear Physics
Goethe University Frankfurt, Germany
Tel. +49 (0)69 798-47003
doerner@atom.uni-frankfurt.de
https://www.atom.uni-frankfurt.de
Shedding new light on the role of tumour suppressor protein pVHL
Transforming Growth Factor beta (TGF-β) is a signalling protein whose dysregulation can cause developmental disorders and cancer. Dr Xinlai Cheng and his colleagues at the Goethe University Frankfurt have discovered how a tumour suppressor known as pVHL influences signal transmission involving TGF-β. Their findings suggest possible starting points for developing new drugs.
FRANKFURT/HEIDELBERG. Signal
transmission inside cells is a complex process. TGF-β, for example, regulates many
cell functions during the early development of both humans and animals, but
also in adult organisms. The mechanisms involved are not yet fully understood. It
is, however, clear that activated TGF-β initially binds to receptors located on
the cell surface. Inside the cell, the TGF-β receptors in their turn activate a
protein called SMAD3, which then forms complexes with SMAD4 that translocate to
the cell nucleus. There the SMAD proteins mediate the extent to which genes are
activated and translated into proteins and other gene products.
Researchers at the Goethe University Frankfurt,
Heidelberg University, the German Cancer Research Center (DKFZ), Heidelberg
University Hospital and the University Hospital in Jena have now discovered how
the von Hippel-Lindau tumour suppressor protein (pVHL) intervenes in this
signalling pathway. Tumour suppressors are proteins whose defects or reduced
presence in multicellular organisms are associated with a high risk that cells
will degenerate into tumour cells. In the Journal of Cell Biology the scientists
report the first evidence that pVHL degrades the SMAD3 protein. This occurs before
SMAD3 and SMAD4 associate. pVHL thus inhibits the signalling chain that starts
with activated TGF-β. “We obtained evidence of this both in cultures of human
cells and in Drosophila," says the last author, Dr
Xinlai Cheng. “This suggests that at a very early stage in evolution pVHL
assumed the regulatory function that we have now brought to light."
Xinlai Cheng has been leading a junior research group
at the Buchmann Institute for Molecular Life Sciences at the Goethe University
Frankfurt since 2019. He began the investigations at the Institute of Pharmacy
and Molecular Biotechnology at Heidelberg University. His mentor, Professor
Stefan Wölfl, explained an important finding that emerged from the new-found connection
between pVHL and the TGF-β signalling pathway: “pVHL is known to be involved in
how cells 'feel' oxygen and react to varying oxygen availability. As a result, a
cell's oxygen supply also mediates TGF-β signal transmission."
The researchers' discovery opens up new opportunities for
developing drugs to combat cancer. “If we could, for example, use a substance
to specifically regulate pVHL activity, we would also influence the TGF-β
signalling pathway, which in turn plays a major role in the formation of
tumours, and metastases in particular," says Xinlai Cheng. Tumour cells are
good at adapting to their environment inside the organism and to variations in oxygen
availability. Their very flexible cellular activity helps them to do so. This
activity is regulated by factors including the TGF-β signalling pathway.
Publication:
Jun Zhou, Yasamin Dabiri, Rodrigo A. Gama-Brambila, Shahrouz
Ghafoory, Mukaddes Altinbay, Arianeb Mehrabi, Mohammad Golriz, Biljana
Blagojevic, Stefanie Reuter, Kang Han, Anna Seidel, Ivan Đikić, Stefan
Wölfl, Xinlai Cheng: pVHL-mediated SMAD3
degradation suppresses TGF-β signaling. Journal of
Cell Biology (2022) 221 (1): e202012097 https://doi.org/10.1083/jcb.202012097
Picture
download:
https://www.uni-frankfurt.de/112400017
Caption: Stained liver tissue shows the
complementary occurrence of pVHL and SMAD proteins: Where pVHL (green) is
abundant, SMAD2/3 (red) is scarce, and vice versa. Cell nuclei are stained
blue. The lower right picture shows all three colours combined. Photos: Xinglai
Cheng/Goethe University
Further
Information:
Dr.
rer. nat. habil. Xinlai Cheng
Buchmann Institute for Molecular Life Sciences Chemical Biology
AK Cheng
Goethe University Frankfurt
Phone +49 69 798-42718
Cheng@pharmchem.uni-frankfurt.de
Professor Stefan
Wölfl
Institut of Pharmacy and Molecular Biotechnology –
Pharmaceutical Biology, Pharmaceutical Bioanalytics and Molecular Cell Biology
Heidelberg University
Phone +49 6221-544880
wolfl@uni-hd.de