Magnetosensitive neurons mediate geomagnetic orientation in Caenorhabditis elegans

Abstract

Many organisms spanning from bacteria to mammals orient to the earth's magnetic field. For a few animals, central neurons responsive to earth-strength magnetic fields have been identified; however, magnetosensory neurons have yet to be identified in any animal. We show that the nematode Caenorhabditis elegans orients to the earth's magnetic field during vertical burrowing migrations. Well-fed worms migrated up, while starved worms migrated down. Populations isolated from around the world, migrated at angles to the magnetic vector that would optimize vertical translation in their native soil, with northern- and southern-hemisphere worms displaying opposite migratory preferences. Magnetic orientation and vertical migrations required the TAX-4 cyclic nucleotide-gated ion channel in the AFD sensory neuron pair. Calcium imaging showed that these neurons respond to magnetic fields even without synaptic input. C. elegans may have adapted magnetic orientation to simplify their vertical burrowing migration by reducing the orientation task from three dimensions to one.DOI: http://dx.doi.org/10.7554/eLife.07493.001

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“…It is important to also note that there have been no attempts to determine whether an MPM system exists in reptiles, amphibians or crustaceans, despite the strong evidence for a magnetic map sense in turtles, newts and spiny lobsters [111][112][113]. Additionally, the recent implication of AFD sensory neurons in geomagnetic orientation in Caenorhabditis elegans [114] provides a clear opportunity to microscopically examine a well-defined region of interest for putative magnetoreceptive cells. Further scrutiny could be given to each of these groups in future studies.…”

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“…It is suggested that endogenous magnetic material, previously reported in C . elegans , may be also involved (26,31). In our experiments, the locomotive behavior of Group C worms, which do not contain any particles, does not seem to be affected by the externally applied MF (Fig.…”

“…Our findings are added to the recent discoveries on C . elegans magnetotactic behavior (26) and are among the few available data on the in vivo effect of internally localized MFs (70, 71). The effect that localized MFs may have on animals' behavior and thus on the functionality of excitable cells, combined with the capability of controlling these fields by using particles of different properties, could pave the way for more detailed studies on the sensitivity of biological systems to MFs.…”

“…elegans was recently demonstrated (26), and authors report that nematodes migrate in response to the direction of Earth's MF, with the participation of AFD 15, 2018; neurons, the first neurons to be identified as magnetosensory. It is suggested that endogenous magnetic material, previously reported in C .…”

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