MAGNETORECEPTION AND ITS NEURAL BASIS IN SPINY LOBSTERS Public Deposited

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  • March 22, 2019
Creator
  • Ernst, David
    • Affiliation: College of Arts and Sciences, Department of Biology
Abstract
  • The research presented here investigates magnetoreception (the ability to detect Earth’s magnetic field) and its underlying mechanisms in the Caribbean spiny lobster, Panulirus argus. Spiny lobsters are the only invertebrates known to detect and use directional and positional information from Earth’s magnetic field. Despite decades of research, we still do not know how lobsters, or indeed any animals, are able to perceive magnetic fields. To shed light on this elusive sensory modality, I examine the behavioral and transcriptomic responses of lobsters to strong magnetic stimuli. Behavioral studies revealed that lobsters actively avoid dens with a strong magnetic anomaly and that lobster size is a predictor of avoidance behavior. On average, lobsters that chose dens with the anomaly were significantly smaller than those that chose dens with a non-magnetic weight. These findings are consistent with magnetoreception in lobsters, suggest ontogenetic variation in the lobster’s response to magnetic fields, and indicate that magnetic anomalies might affect the movements of lobsters and other animals in the natural environment. In additional behavioral studies testing the ‘magnetite hypothesis’ of magnetoreception, lobsters were subjected to a strong magnetic pulse (a stimulus thought to disrupt magnetoreceptors based on permanently magnetic material, such as magnetite), and their subsequent orientation was tested. In contrast to controls, lobsters exposed to the pulse displayed directed orientation, consistent with magnetite-based magnetoreception. Finally, transcriptomic approaches were used to identify candidate genes associated with magnetoreception and to determine the effects of a magnetic pulse on the lobster central nervous system. Hundreds of genes were differentially expressed throughout the nervous system in response to the pulse, many of which were associated with iron regulation and the oxidative effects of free iron on cells. These findings are consistent with the hypothesis that iron-based magnetoreceptors in the lobster central nervous system are disrupted or damaged by pulse magnetization. Furthermore, genes linked to diverse biological functions that are likely not linked to magnetoreceptors showed altered expression, suggesting that the pulse treatment had a significant impact on neural physiology. Together, these findings provide novel and significant insights into the mechanisms underlying magnetoreception and the physiological effects of pulse magnetization.
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Advisor
  • Kier, William
  • Pfennig, Karin
  • Lohmann, Kenneth
  • Johnsen, Sönke
  • Lohmann, Catherine
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2018
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