Genetic Dissection of the <i>Drosophila</i> Nervous System by Means of Mosaics

TLDR

Genetic mosaicism, including sex mosaics or gynandromorphs, enables identification of the anatomical domain responsible for abnormal behavior by creating organisms with distinct mutant and normal regions. The authors tested five X‑chromosome genes with visual defects in *Drosophila melanogaster* using this mosaic approach. All five mutants were found to be autonomous, with mutant eyes always abnormal regardless of surrounding normal tissue, indicating that behavioral deficits originate within the eye.

Abstract

Given a mutant having abnormal behavior, the anatomical domain responsible for the deficit may be identified by the use of genetic mosaicism. Individuals may be produced in which a portion of the body is mutant male while the rest is normal female. In such sex mosaics, or gynandromorphs, the division line between normal and mutant parts can occur in various orientations. Mutants of five different genes (cistrons) on the X-chromosome of Drosophila melanogaster, having various abnormalities in visual function, have been tested by this method. All of these have been found to be autonomous, i.e., a mutant eye always functions abnormally, regardless of the amount of normal tissue present elsewhere, indicating that the primary causes of the behavioral deficits in these mutants are within the eye.