December 2024 ESRFnews
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a longstanding question about the neural makeup of
squids and other cephalopods: whether they think
thoughts purely in their heads, as we do, or whether
their unusually distributed nervous systems allows their
tentacles (as seen in the zoomed-in portion, previous
page) to have something like independent brains, and
some degree of autonomy.
A lot of the ID16A connectomics research
has focused on the fruit fly an organism that
shares 60 of its DNA with humans One of the
obvious features of flies is how fast they move too
fast for us to observe properly most of the time even
though their underlying neural mechanisms are
probably similar to ours Like us they rely on sensors
known as proprioceptors to know where their limbs are
and how they are moving without relying on visual cues
Last year a group led by the University of Washington
in Seattle US used XNH at ID16A to reconstruct the
structure of a particular fruit fly proprioceptor known
as the femoral chordotonal organ Combining the data
with RNA sequencing, the researchers discovered that
the different sensors in the organ are similar genetically,
but connected to the fly’s leg structure in different
ways mechanically, allowing the fly to keep track of its
legs’ joint angles (Neuron 111 P3230-3243.E14). “We
discovered that the way these sensors are built, and how
they interact with the leg’s structure, is more important
for their job than differences in gene expression says
University of Washington biophysicist John Tuthill
This year the researchers took the work a step further
combining XNH data of the legs and wings with EM
data of the flys ventral nerve cord the insect equivalent
of a spinal cord The pairing allowed them to work out
which neural circuit controls specific parts of the legs
and wings for specific functions such as walking take
off flying and steering Nature631 360
Some of the most impressive developments might
emerge when XNH findings are combined with other
techniques see Imaging life science at the ESRF
above Drawing on hierarchical tomographic data at
CONNECTOMICS
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IMAGING LIFE SCIENCE
Creating an “atlas”of human organs
An unprecedented success of the ESRF’s
EBS upgrade has been the invention of a
hierarchical imaging method, HiP-CT, which
can image entire human organs in three-
dimensions, without destroying them, down
to micron resolution – enough to zoom in
on individual cells. Indeed, an international
consortium of scientists, led by the ESRF
and University College London in the UK,
and co-funded by the Chan Zuckerberg
Initiative, is set on exploiting the method to
create a Human Organ Atlas – a free image
database of all human organs, healthy and
diseased (https://human-organ-atlas.esrf.
fr/). Taken this year, their latest images are of
healthy and diseased human hearts (below).
It is believed the images could help in
studies of arrhythmia, or provide more lifelike
models for surgical training.
Trails of toxicity
The presence of toxic nanoparticles in the food
chain is of increasing concern, but they are hard to
trace – unless you use synchrotron X-rays. At the
ESRF, X-ray f luorescence mapping at the ID16B
beamline and X-ray absorption spectroscopy
at ID21 (see News, p9), for example, can detect
and distinguish between multiple elements down
to resolutions of tens of nanometres. This year,
a team led by the Université Grenoble Alpes
in France used these techniques to discover
how certain cacao trees protect themselves
from the toxic metal cadmium (X-ray absorption
spectroscopy map below) by storing it in crystals
of calcium oxalate in the roots and branches
– f indings that could help in the breeding of safer
cacao cultivars for making chocolate (Environ.
Exp. Bot. 221 105713). The researchers are
continuing their studies, using other types of
cacao plants.
Validating new methods of drug testing
Synchrotron X-rays – and particularly
those from the EBS – set the benchmark
for X-ray imaging in biomedicine, but they
can help without needing to be part of a
routine methodology. Often, they can be
used to check the performance of more
widely accessible instruments. This year, for
instance, a team led by the Georg-August-
University of Göttingen in Germany used
X-ray phase-contrast tomography (XPCT)
– both in nanoscale resolution (below)
at the ESRF’s ID16A beamline, and in
microscale resolution at Germany’s DESY
synchrotron – to validate the output of a new,
high-throughput XPCT system designed
for laboratory X-ray sources. Tested on the
lungs of hamsters with COVID-19, the system
will be used for testing dif ferent drugs (Sci.
Rep. 14 12348).
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