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ROLE OF THE ANTENNAE IN GRAVITY SENSING BY DROSOPHILA MELANOGASTER.  G. Hetrick, C. S. Miller and K. Beckingham  Dept. Biochemistry and Cell Biology, Rice University, TX.

   In many organisms, a clearly defined gravity sensing organ of the ‘statocyst’ type is present.  In Dipteran insects, no such organ has been identified and thus gravity perception must entail other sensory devices.  There is evidence that gravity sensing may involve a diverse array of sense organs including proprioceptors in the legs and body wall.  Horn and Kessler (J. Comp. Physiol. 97, 189-203) have also provided evidence that the antennae are a major site of gravity perception in the Dipteran Calliphora erythrocephala.  The Beckingham lab has identified a number of mutations that affect gravity perception during walking in the Diperan Drosophila melanogaster.  The mutant flies were identified using gravitaxic mazes in which the flies make eight up/down choices and thus emerge at one of nine exits.  Recent work to determine which tissues are affected by the mutations suggests that in many of these mutants the defective gene product is expressed in the antennae.  Other sense organs on the head are also implicated.  The mutant gene expression patterns will be presented.

   To address further the role of the antennae, experimental manipulation of the antenna is being performed and the effects on gravity perception subsequently assayed.  These results will also be reported.

(Supported by NIH grant DC05164-02, and the Century Scholars Program at Rice University).

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