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Magnetic Compass Orientation in
Drosophila melanogaster
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The apparatus used for testing the
magnetic compass response of Drosophila has a double
coil for shifting the horizontal alignment of the magnetic field
(black cube), and a larger vertical coil, which is used to invert
the vertical component of the magnetic field.
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Flies are 'trained' to exhibit a consistent direction
of magnetic compass orientation by exposing bottles of flies
to a directional light source coming from one of four directions.
Schematic diagrams on the right (upper figure--side view, lower
figure--top view) show how light from an overhead light source
is scattered from the sides of a frosted aluminum pyramid (gray
shading) into the four arms of the training apparatus.
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Groups of flies are placed in a cool moist holding tube
at the center of an 8-arm maze used for testing.
A release mechanism covering the holding tube
is used to release the flies after a 60 sec
delay. Flies exit the maze through one of the
8 arms, and are captured in funnel traps leading
up into inverted test tubes. Frosted aluminum
reflectors at the ends of the arms are adjusted
to minimize any differences in light intensity
entering the 8 arms (< 0.05 log units). |
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