Persistent one-way walking in a circular arena inDrosophila melanogasterCanton-S strain

We describe persistent one-way walking of Drosophila melanogaster in a circular arena. Wild-type Canton-S adult flies walked in one direction, counter-clockwise or clockwise, for minutes, whereas white-eyed mutant w 1118 changed directions frequently. Locomotion in the circular arena could be classified into four components: counter-clockwise walking, clockwise walking, nondirectional walking and pausing. Genetic analysis revealed that while wild-type genetic background was associated with reduced directional change and reduced numbers of one-way (including counterclockwise and clockwise) and nondirectional walks, the white ( w + ) locus promoted persistent oneway walking by increasing the maximal duration of one-way episodes. The promoting effect of w + was further supported by the observations that (1) w + duplicated to the Y chromosome, (2) four genomic copies of mini-white inserted on the autosomes, and (3) pan-neuronal overexpression of the White protein increased the maximal duration of one-way episodes, and that RNAi knockdown of w + in the neurons decreased the maximal duration of one-way episodes. These results suggested a pleiotropic function of w + in promoting persistent one-way walking in the circular arena.