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Fundamental research for novel approaches for the control of Trypanosoma parasites
In Central and South America, predatory blood-sucking bugs transmit the causative agent of the widely prevalent Chagas disease. As the disease can induce severe symptoms and to date there is no vaccine against the Trypanosoma parasites, the main approach at present is to control the bug using insecticides. A German-Brazilian research team has now studied how trypanosomes change the bug's intestinal microbiota. The long-term goal: to change the bacterial community in the predatory bug's intestine in such a way that it can defend itself against the trypanosomes.
FRANKFURT. According
to estimates by the World Health Organization (WHO), between six and seven
million people worldwide, predominantly in Central and South America, are
infected with the Trypanosoma cruzi species
of trypanosome. This
single-celled (protozoan) parasite causes Chagas disease (American trypanosomiasis),
which in the acute phase is inconspicuous: only in every third case does the infected
person develop any symptoms at all, which can then be unspecific, such as
fever, hives and swollen lymph nodes. However, the parasites remain in the body,
and many years later chronic Chagas disease can become life-threatening, with pathological
enlargement of the heart and progressive paralysis of the gastrointestinal
tract.
There is no vaccine against the pathogen
and treating the disease in the advanced stage is difficult. That is why the
focus in Latin America is rather on controlling the bug that transmits Chagas
trypanosomes: the predatory blood-sucking bug of the insect subfamily Triatominae. It ingests the trypanosomes
during the sting, which then colonize its intestine. Through its faeces that it
mostly deposited next to the bite, the bug excretes the pathogen, which is
often rubbed into the wound when scratching the extremely itchy bite.
Although the number of new infections has
dropped in various regions where insecticides are sprayed on a wide scale,
problems are emerging: over the last decade, resistance to common insecticides
by several species of predatory bugs has been increasingly observed. These
insecticides also have a negative impact on the environment and the local population.
Researchers worldwide are making intense
efforts to find alternative methods to help control Trypanosoma cruzi. One possibility might be to modify bacteria in
the predatory bug's intestine in such a way that they eliminate the Chagas trypanosomes
or inhibit their development.
In collaboration with scientists at the
Instituto René Rachou in Belo Horizonte, Brazil, parasitologists and infection
biologists Fanny Eberhard and Professor Sven Klimpel from Goethe University, the
Senckenberg – Leibniz Institution for Biodiversity and Earth System Research
(SGN) and the LOEWE Centre for Translational Biodiversity Genomics have now investigated
how Chagas trypanosomes change the bacterial community in the predatory bug's
intestine. To do so, they used genome analysis, which allowed them to compare
the composition of the bacterial community in the bug's intestine, the
microbiome, before and after infection with the pathogen (metagenomic shotgun sequencing).
The result: after the infection, the range
of bacterial strains in the bug's intestine significantly decreased. Certain
strains, including the potentially pathogenic bacterium Enterococcus faecalis, profited from the parasites' presence.
Moreover, the researchers succeeded in identifying four bacterial species that
probably take on functions important for the bug, such as the synthesis of B
vitamins.
Fanny Eberhard explains: “Vitamin B is one
of the nutrients that blood-sucking insects do not obtain through their blood
meals. Bacteria that produce vitamin B are therefore very important for the
bug, are found in practically all individuals and stay in the predatory bug's
intestine even across generations. Hence, such bacteria are potentially
suitable recipients for genes that produce defensive substances against Chagas
trypanosomes."
Professor Sven Klimpel elaborates: “Ultimately,
our goal is for the predatory bug to defend itself against Chagas trypanosomes and,
in this way, to prevent infection in humans. However, before we can produce
bacteria with such properties and then release predatory bugs containing them,
we need to understand better how the ecology of the bug's intestine is
structured and how the extensive interactions between host, pathogen and microbiome
function. Our work is delivering an essential contribution to this."
Publication:
Fanny E. Eberhard, Sven Klimpel,
Alessandra A. Guarneri, Nicholas J. Tobias. Exposure to Trypanosoma parasites induces changes in the microbiome of the
Chagas disease vector Rhodnius prolixus.
Microbiome (2022) 10:45. https://doi.org/10.1186/s40168-022-01240-z
Picture
download: https://www.uni-frankfurt.de/116081371
Captions:
Rhodnius prolixus_1000px.jpg
The predatory bug Rhodnius prolixus is one of the main vectors of Chagas disease in
the north of South America and in Central America. Photo: Dr Erwin Huebner,
University of Manitoba, Winnipeg, Canada/ Wikimedia Commons
Rhodnius prolixus_Life_cycle.jpg
Example of the hemimetabolic life cycle of the predatory
triatomine bug Rhodnius prolixus. Shown
are the adult vector, freshly laid, milky-white eggs, mature, reddish eggs and
five nymphs. Red arrows mark a blood meal for the moulting process and egg
production. Pictured in the middle are frequent hosts, such as dogs, opossums
and humans. Graphics: Fanny E. Eberhard
Further
information:
Professor Sven Klimpel
Institute of Ecology, Diversity and Evolution, Goethe University
Senckenberg – Leibniz Institution for Biodiversity and Earth System Research
(SGN)
LOEWE Centre for Translational
Biodiversity Genomics
Tel. +49 (0)69 798-42249
Klimpel@bio.uni-frankfurt.de
https://www.bio.uni-frankfurt.de/43925886/Abt__Klimpel
POLY research group offers fellowships for researchers forced to leave Ukraine
The POLY research group on premodern Christianities at Goethe University is offering five fellowships to Ukrainian academics specialised in medieval or early modern history.
FRANKFURT. The
Russian attack on Ukraine is endangering the lives and work of many
researchers. To help some of them to continue their research outside Ukraine,
the “Polycentricity and Plurality of Premodern Christianities” (POLY) research
group, a Centre for Advanced Studies in Humanities funded by the German
Research Foundation, is offering five fellowships. These are intended for
scholars with a doctoral degree who are dealing with medieval or early modern history
and focus especially on religious diversity.
“With this initiative, we at POLY want to
help colleagues from Ukraine forced to flee to safety and to give a stronger
voice to Ukrainian science and research,” says Professor Birgit Emich, chair of
the POLY fellowship programme, summing up the research group’s motivation. For
Emich, who teaches early modern history at Goethe University, the fellowships also
offer great opportunities for research in Frankfurt: “With the help of these
visiting scholars, we aim to develop further partnerships in this region, which
is so rich for the study of religious diversity.”
The fellowships are endowed with €3,000
per month and initially limited to four months. During the funding period, the visiting
Ukrainian scholars will not only be integrated in work within POLY but also
profit from other research infrastructure at Goethe University, notably, the
research alliance “Dynamics of Religion”, co-chaired by Emich and Christian
Wiese, theologian and professor for Jewish studies.
Applications for fellowships are now being
accepted. They are conditional on a completed doctoral degree and an academic
focus on religious plurality in the medieval or early modern period.
Further
information
Professor Birgit Emich
Institute of History
Chair of Early Modern History
Goethe University
Tel.: +49 (0) 69 798-32594
Email: emich@em.uni-frankfurt.de
https://www.geschichte.uni-frankfurt.de/92594738/Polycentricity_and_Plurality_of_Premodern_Christianities__POLY
Editor: Dr. Anke Sauter, Science Editor, PR & Communication Office, Tel. +49 69 798-13066, Fax + 49 69 798-763-12531, sauter@pvw.uni-frankfurt.de
Crystals grown at Goethe University Frankfurt with rare-earth atoms display surprising, fast adjustable magnetic properties.
Computer chips and storage elements are expected to function as quickly as possible and be energy-saving at the same time. Innovative spintronic modules are at an advantage here thanks to their high speed and efficiency, as there is no lossy electrical current, rather the electrons couple with one another magnetically – like a series of tiny magnetic needles which interact with almost no friction loss. A team of scientists involving Goethe University Frankfurt and the Fritz Haber Institute in Berlin has now found promising properties with crystals grown from rare-earth atoms, which offer hope on the long path towards usage as spintronic components.
FRANKFURT. While
modern computers are already very fast, they also consume vast amounts of
electricity. For some years now a new technology has been much talked about,
which although it is still in its infancy could one day revolutionise computer
technology – spintronics. The word is a portmanteau meaning “spin” and “electronics”,
because with these components electrons no longer flow through computer chips, but
the spin of the electrons serves as the information carrier. A team of
researchers with staff from Goethe University Frankfurt has now identified
materials that have surprisingly fast properties for spintronics. The results
have been published in the specialist magazine “Nature Materials”.
“You have to imagine the electron spins as
if they were tiny magnetic needles which are attached to the atoms of a crystal
lattice and which communicate with one another,” says Cornelius Krellner,
Professor for Experimental Physics at Goethe University Frankfurt. How these
magnetic needles react with one another fundamentally depends on the properties
of the material. To date ferromagnetic materials have been examined in
spintronics above all; with these materials – similarly to iron magnets – the magnetic
needles prefer to point in one direction. In recent years, however, the focus
has been placed on so-called antiferromagnets to a greater degree, because
these materials are said to allow for even faster and more efficient
switchability than other spintronic materials.
With antiferromagnets the neighbouring magnetic
needles always point in opposite directions. If an atomic magnetic needle is
pushed in one direction, the neighbouring needle turns to face in the opposite
direction. This in turn causes the next but one neighbour to point in the same
direction as the first needle again. “As this interplay takes place very
quickly and with virtually no friction loss, it offers considerable potential
for entirely new forms of electronic componentry,” explains Krellner.
Above all crystals with atoms from the
group of rare earths are regarded as interesting candidates for spintronics as
these comparatively heavy atoms have strong magnetic moments – chemists call
the corresponding states of the electrons 4f orbitals. Among the rare-earth
metals – some of which are neither rare nor expensive – are elements such as praseodymium
and neodymium, which are also used in magnet technology. The research team has
now studied seven materials with differing rare-earth atoms in total, from praseodymium
to holmium.
The problem in the development of
spintronic materials is that perfectly designed crystals are required for such
components as the smallest discrepancies immediately have a negative impact on
the overall magnetic order in the material. This is where the expertise in
Frankfurt came into play. “The rare earths melt at about 1000 degrees Celsius,
but the rhodium that is also needed for the crystal does not melt until about 2000
degrees Celsius,” says Krellner. “This is why customary crystallisation methods
do not function here.”
Instead the scientists used hot indium as
a solvent. The rare earths, as well as the rhodium and silicon that are
required, dissolve in this at about 1500 degrees Celsius. The graphite crucible
was kept at this temperature for about a week and then gently cooled. As a
result the desired crystals grew in the form of thin disks with an edge length
of two to three millimetres. These were then studied by the team with the aid
of X-rays produced on the Berlin synchrotron BESSY II and on the Swiss Light
Source of the Paul Scherrer Institute in Switzerland.
“The most important finding is that in the
crystals which we have grown the rare-earth atoms react magnetically with one
another very quickly and that the strength of these reactions can be
specifically adjusted through the choice of atoms,” says Krellner. This opens
up the path for further optimisation – ultimately spintronics is still purely
fundamental research and years away from the production of commercial components.
There are still a great many problems to
be solved on the path to market maturity, however. Thus, the crystals – which
are produced in blazing heat – only deliver convincing magnetic properties at temperatures
of less than minus 170 degrees Celsius. “We suspect that the operating
temperatures can be raised significantly by adding iron atoms or similar
elements,” says Krellner. “But it remains to be seen whether the magnetic
properties are then just as positive.” Thanks to the new results the
researchers now have a better idea of where it makes sense to change parameters,
however.
Publication:
Y. W. Windsor, S.-E. Lee, D. Zahn, V.
Borisov, D. Thonig, K. Kliemt, A. Ernst, C. Schüßler-Langeheine, N. Pontius, U.
Staub, C. Krellner, D. V. Vyalikh, O. Eriksson, L. Rettig: Exchange scaling of ultrafast angular momentum transfer in 4f
antiferromagnets. Nature Materials (2022) https://www.nature.com/articles/s41563-022-01206-4
Further
Information:
Prof. Dr. Cornelius Krellner
Crystal and Materials Laboratory
Institute of Physics
Phone: +49 (0)69 798-47295
krellner@physik.uni-frankfurt.de
An international team of scientists at the European XFEL has taken a snapshot of a cyclic molecule using a novel imaging method. Researchers from the European XFEL, DESY, Universität Hamburg and the Goethe University Frankfurt and other partners used the world's largest X-ray laser to explode the molecule iodopyridine in order to construct an image of the intact molecule from the resulting fragments. (Nature Physics, DOI 10.1038/s41567-022-01507-0).
SCHENEFELD/FRANKFURT. Exploding
a photo subject in order to take its picture? An international research team at
the European XFEL, the world's largest X-ray laser, applied this “extreme"
method to take pictures of complex molecules. The scientists used the
ultra-bright X-ray flashes generated by the facility to take snapshots of
gas-phase iodopyridine molecules at atomic resolution. The X-ray laser caused
the molecules to explode, and the image was reconstructed from the pieces.
“Thanks to the European XFEL's extremely intense and particularly short X-ray
pulses, we were able to produce an image of unprecedented clarity for this
method and the size of the molecule," reports Rebecca Boll from the European
XFEL, principal investigator of the experiment and one of the two first authors
of the publication in the scientific journal Nature Physics in which the team
describes their results. Such clear images of complex molecules have not been
possible using this experimental technique until now.
The images are an important step towards
recording molecular movies, which researchers hope to use in the future to observe
details of biochemical and chemical reactions or physical changes at high
resolution. Such films are expected to stimulate developments in various fields
of research. “The method we use is particularly promising for investigating
photochemical processes," explains Till Jahnke from the European XFEL and the
Goethe University Frankfurt, who is a member of the core team conducting the
study. Such processes in which chemical reactions are triggered by light are of
great importance both in the laboratory and in nature, for example in
photosynthesis and in visual processes in the eye. “The development of
molecular movies is fundamental research," Jahnke explains, hoping that “the
knowledge gained from them could help us to better understand such processes in
the future and develop new ideas for medicine, sustainable energy production
and materials research."
In the method known as Coulomb explosion
imaging, a high-intensity and ultra-short X-ray laser pulse knocks a large
number of electrons out of the molecule. Due to the strong electrostatic
repulsion between the remaining, positively charged atoms, the molecule
explodes within a few femtoseconds – a millionth of a billionth of a second.
The individual ionised fragments then fly apart and are registered by a
detector.
"Up to now, Coulomb explosion imaging
was limited to small molecules consisting of no more than five atoms,"
explains Julia Schäfer from the Center for Free-Electron Laser Science (CFEL)
at DESY, the other first author of the study. "With our work, we have
broken this limit for this method." Iodopyridine (C5H4IN) consists of
eleven atoms.
The film studio for the explosive molecule
images is the SQS (Small Quantum Systems) instrument at the European XFEL. A
COLTRIMS reaction microscope (REMI) developed especially for these types of
investigations applies electric fields to direct the charged fragments onto a
detector. The location and time of impact of the fragments are determined and
then used to reconstruct their momentum – the product of mass and velocity –
with which the ions hit the detector. “This information can be used to obtain
details about the molecule, and with the help of models, we can reconstruct the
course of reactions and processes involved," says DESY researcher Robin Santra,
who led the theoretical part of the work.
Coulomb explosion imaging is particularly
suitable for tracking very light atoms such as hydrogen in chemical reactions.
The technique enables detailed investigations of individual molecules in the
gas phase, and is therefore a complementary method for producing molecular
movies, alongside those being developed for liquids and solids at other
European XFEL instruments.
“We want to understand fundamental
photochemical processes in detail. In the gas phase, there is no interference
from other molecules or the environment. We can therefore use our technique to
study individual, isolated molecules," says Jahnke. Boll adds: “We are working
on investigating molecular dynamics as the next step, so that individual images
can be combined into a real molecular movie, and have already conducted the
first of these experiments."
The investigations involved researchers
from Universität Hamburg, the Goethe University Frankfurt, the University of
Kassel, Jiao Tong University in Shanghai, Kansas State University, the Max
Planck Institutes for Medical Research and for Nuclear Physics, the Fritz Haber
Institute of the Max Planck Society, the US accelerator laboratory SLAC, the
Hamburg cluster of excellence CUI: Advanced Imaging of Matter, the Center for
Free-Electron Laser Science at DESY, DESY and the European XFEL.
Publication:
Rebecca Boll, Julia M. Schäfer, et al. X-ray multiphoton-induced Coulomb explosion images complex single
molecules. Nature Physics, 2022, https://www.nature.com/articles/s41567-022-01507-0
Picture
download:
https://media.xfel.eu/XFELmediabank/?language=en#l=en&cid=26753&cname=Coulomb-Explosion%20(20.01.2022)&f=&s=&p=&r=
Captions:
Model of the molecule Iodopyridine (molecule_A.jpg):
The ring is formed by carbon atoms (grey) and a nitrogen atom (blue). The
iodine atom (violet) is on the outside of the ring. Credit: European XFEL /
Rebecca Boll, Till Jahnke
Coulomb
Explosion Imaging of hydrogen atoms
(protons_B.jpg):
In this Coulomb
Explosion Imaging result, the scientists have concentrated on the hydrogen
atoms (violet). Here the shape of the ring can be seen better because the
hydrogen atoms are the first to be emitted from the molecule due to a charge-up
of the ring-atoms. The heavier nitrogen atom is emitted later in the process,
when more charge has been accumulated. Accordingly, due to larger repulsion its
momentum is larger than that of the hydrogen atoms.
Credit: European XFEL / Rebecca Boll, Till Jahnke
Coulomb Explosion Image of carbon and
nitrogen atoms (Carbons_C.jpg):
The Coulomb Explosion Image of the molecule shows in detail the carbon atoms
(red) and the nitrogen atom (green). The ring appears distorted because the
detector does not register a direct image but the momentum of the fragments
from the explosion, i.e., the product of their mass and velocity. The iodine
atom is not displayed as it defines the horizonal axis of the momentum space
coordinate system. Credit: European XFEL / Rebecca Boll, Till Jahnke
Further
Information:
Professor Till Jahnke
European XFEL and
Institute for Nuclear Physics, Goethe-University Frankfurt
Phone: + 49 (0)69-798 47023 (Secretary)
till.jahnke@xfel.eu
Rebecca Boll, Ph.D.
European XFEL
Phone: +49 (0)40 8998 6244
Phone: +49 (0)40 8994 1905
rebecca.boll@xfel.de
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
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.