Meeting Abstract

77.4  Tuesday, Jan. 6  Light-dependent magnetic compass of larval Drosophila. PHILLIPS, John B.*; DOMMER, David H.; TRAN, Dan Q.; GNIRKE, Matthew H.; FLINT, Christopher D.; PAINTER, Michael S.; Virginia Tech, Blacksburg, VA jphillip@vt.edu

A light-dependent magnetic compass has been demonstrated in taxonomically diverse animals. The radical pair mechanism (RPM) implicates a specialized photoreceptor in magnetoreception and proposes that the alignment of an earth-strength magnetic field can modulate photosensitivity in a specialized receptor containing an ordered array of light-absorbing molecules. The magnetic field may be perceived as an axially symmetrical pattern of light intensity/color superimposed on the organisms visual field, or may be sensed by a separate light-dependent pathway independent of vision. To date, however, the biophysical process underlying the light-dependent magnetic compass has not been characterized in any organism. Here we show that the behavior of a simple organism, larval Drosophila melanogaster, can be used to visualize the primary biophysical process underlying the light-dependent magnetic compass, revealing; (1) an axially symmetrical, 3-dimensional pattern of response unique to the radical pair mechanism (RPM) and (2) an antagonistic interaction of short- and long-wavelength light consistent with wavelength-dependent effects of light on magnetic compass orientation observed in amphibians and adult Drosophila. Larval Drosophila provide a critical link between the properties suggested by theoretical models and artificial radical pair systems, and those observed in the behavioral responses of more complex organisms.