Using tiny microphones suspended among flowers, the team recorded the buzzing of the bees through all stages of the eclipse. The bees were active and noisy right up to the last moments before totality, the part of a total solar eclipse when the moon blocks all direct sunlight, and a night-like darkness settles over the land. As totality hit, the bees went totally silent in unison.
Magnetoreception refers to the ability of some animals to sense
Earth’s magnetic field and make use of it for navigation. Still, the
underlying mechanisms remain unknown. “To solve this question might not
only satisfy neuroscientific curiosity but also lead to new molecular
methods”, said Prof. Dr. Gil Gregor Westmeyer. He is the principal
investigator of the study at the interface of neuroscience and molecular
imaging, and his team is affiliated both with Helmholtz Zentrum München
and TUM. “Reverse-engineering the magnetoreceptor may lead to synthetic
biology techniques for remotely controlling molecular processes with
magnetic fields.” To reach this goal, Westmeyer and his team wanted to
establish a model to study magnetoreception.
The scientists focused their work on zebrafish, and distally related
medaka fish because they are vertebrate animals that can be genetically
addressed and analyzed well under the microscope.* The researchers found
that adult fish of both species change their swimming trajectories in
response to a change in the direction of the Earth magnetic field that
was experimentally introduced while carefully controlling for
confounding variables. Interestingly, this effect also occurred in the
absence of visible light such that a photon-independent mechanism has to
be assumed.
“In this model, we can now look for previously unidentified
magnetoreceptor cells, which our behavioral experiments predicted would
involve magnetic material”, said co-first author Ahne Myklatun, a
graduate student in the Westmeyer laboratory.
In addition, the researchers were able to show a similar magnetic
field-dependent effect in young fish larvae. “This is a decisive
advantage because in their early developmental stages, the fish are
still almost transparent”, said Antonella Lauri, a postdoctoral fellow
and joint lead author. “Thus, we can use imaging techniques to study the
brain of the fish during behavioral runs with changing magnetic
fields.” The scientists were already able to identify a candidate region
in the brain - a track that could now lead to the unknown magnetic
receptor cells.
Gil Gregor Westmeyer, principal investigator on this ERC-funded
study, concludes: “Magnetoreception is one of the few senses whose
mechanism is not understood. The kind of multidisciplinary work we
present here will ultimately lead to an understanding of the biophysical
mechanism of magnetoreception and its underlying neuronal computation.
These findings could also offer interesting approaches to engineer
biological systems for the remote control of molecular processes with
magnetic fields.”
