Evidence indicates that certain animals detect and orient themselves to the earth's magnetic field. This capacity may be used in the context of homing, finding mates, and locating food sources, for instance. Although the existence of biosensory apparatus for transducing geomagnetism can be inferred from the orienting responses of diverse animals, little is yet known of the mechanisms of transduction of geomagnetic energy into the nervous system of any multicellular animal. An animal has been found which has two unusual features and which provides an opportunity to achieve an understanding of the physical/biological basis for the geomagnetic sense. The marine nudibranch mollusc, Tritonia diomedia responds to the earth's magnetic field by orienting appropriately when other cues are unavailable. Secondly, in recent experiments, a symmetrical pair of re-identifiable neurons in the animal's brain have been found which respond to changes in the direction of the ambient magnetic field by firing electrical impulses. In this proposal, experiments are described at the behavioral, neurophysiological and molecular level that are designed to (1.) establish the normal behavioral context and use of geomagnetic information, (2) establish interaction between sensory inputs carrying information about rheotactic (water current) and geomagnetic cues, and (3) cellular/molecular experiments to determine the physiological roles of unique peptides found in neurons involved in magnetosensory integration. Little is know of the sensory or other processes in animals which mediate interactions with the earth's magnetic field, or with stronger magnetic fields. These studies may help elucidate these relationships.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
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University of Washington
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Willows, A O; Nikitina, L A; Bezuglov, V V et al. (2000) [The possible functional interaction of serotonin and neuropeptides in embryogenic regulatory processes (experiments on embryos of the mollusk Tritona diomedea)] Ontogenez 31:132-8
Beck, J C; Murray, J A; Willows, A O et al. (2000) Computer-assisted visualizations of neural networks: expanding the field of view using seamless confocal montaging. J Neurosci Methods 98:155-63
Beck, J C; Cooper, M S; Willows, A O (2000) Immunocytochemical localization of pedal peptide in the central nervous system of the gastropod mollusc Tritonia diomedea. J Comp Neurol 425:9-Jan
Pavlova, G A; Willows, A O; Gaston, M R (1999) Serotonin inhibits ciliary transport in esophagus of the nudibranch mollusk Tritonia diomedea. Acta Biol Hung 50:175-84
Malyshev, A Y; Norekian, T P; Willows, A O (1999) Differential effects of serotonergic and peptidergic cardioexcitatory neurons on the heart activity in the pteropod mollusc, Clione limacina. J Comp Physiol A 185:551-60
Gaston, M R (1998) Neuropeptide TPep action on salivary duct ciliary beating rate in the nudibranch mollusc Tritonia diomedea. Invert Neurosci 3:327-33
Willows, A O; Pavlova, G A; Phillips, N E (1998) [Effect of Tritonia neuropeptides and serotonin on ciliary activity] Dokl Akad Nauk 358:839-41
Willows, A O; Pavlova, G A; Phillips, N E (1997) Modulation of ciliary beat frequency by neuropeptides from identified molluscan neurons. J Exp Biol 200:1433-9
Lloyd, P E; Phares, G A; Phillips, N E et al. (1996) Purification and sequencing of neuropeptides from identified neurons in the marine mollusc, Tritonia. Peptides 17:17-23
Murray, J A; Willows, A O (1996) Function of identified nerves in orientation to water flow in Tritonia diomedea. J Comp Physiol A 178:201-9

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