Factors that influence magnetic orientation in Caenorhabditis elegans
Magnetoreceptive animals orient to the earth’s magnetic field at angles that change depending on temporal, spatial, and environmental factors such as season, climate, and position within the geomagnetic field. How magnetic migratory preference changes in response to internal or external stimuli is not understood. We previously found that Caenorhabditis elegans orients to magnetic fields favoring migrations in one of two opposite directions. Here we present new data from our labs together with replication by an independent lab to test how temporal, spatial, and environmental factors influence the unique spatiotemporal trajectory that worms make during magnetotaxis. We found that worms gradually change their average preferred angle of orientation by ~ 180° to the magnetic field during the course of a 90-min assay. Moreover, we found that the wild-type N2 strain prefers to orient towards the left side of a north-facing up, disc-shaped magnet. Lastly, similar to some other behaviors in C. elegans, we found that magnetic orientation may be more robust in dry conditions (< 50% RH). Our findings help explain why C. elegans accumulates with distinct patterns during different periods and in differently shaped magnetic fields. These results provide a tractable system to investigate the behavioral genetic basis of state-dependent magnetic orientation.
KeywordsMagnetic orientation State dependence Nematode Migration Humidity
Nematode growth medium
AFD sensory neuron pair
We wish to acknowledge the Caenorhabditis Genetics Center, which is supported by the National Institutes of Health (NIH), as well as NIH and National Science Foundation Grants to AV-G. (1818140 and R15AR068583) and JP. (R01NS075541 and 1RF1AG057355). DAG. and CSC. are funded by the National Science Agency, CONICET and University of Quilmes, Argentina. The authors declare that they have no competing interests.
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Conflict of interest
The authors declare that they have no conflict of interest.
Supplementary Video 1. Centroid tracks of worms migrating in an earth-strength magnetic field. Sample video of animals at the center of an assay plate in the presence of a unidirectional 1xearth (0.65 Gauss) magnetic field parallel to the plate’s surface and with north pointing towards the right of the field of view. This movie compresses the initial 30 minutes of a 90-minute assay. Worms start at the center of a 36 x 27-mm field of view (black dot) and are tracked after they exit the central area of the plate (radius = 5 mm). Most animals exit the center of the plate at different times. However, over the initial 30 minutes most animals travel in a similar direction (blue centroid tracks) (MP4 3863 KB)
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