Frequency-specific modification of locomotor components by the white gene in Drosophila melanogaster adult flies.

The classic eye-color gene white (w) in Drosophila melanogaster (fruitfly) has unexpected behavioral consequences. How w affects locomotion of adult flies is largely unknown. Here, we show that a mutant allele (w1118 ) selectively increases locomotor components at relatively high frequencies (> 0.1 Hz). The w1118 flies had reduced transcripts of w+ from the 5' end of the gene. Male flies of w1118 walked continuously in circular arenas while the wildtype Canton-S walked intermittently. Through careful control of genetic and cytoplasmic backgrounds, we found that the w1118 locus was associated with continuous walking. w1118 -carrying male flies showed increased median values of path length per second (PPS) and 5-min path length compared with w+ -carrying males. Additionally, flies carrying 2-4 genomic copies of mini-white+ (mw+ ) in the w1118 background showed suppressed median PPSs and decreased 5-min path length compared with controls, and the suppression was dependent on the copy number of mw+ . Analysis of the time-series (i.e., PPSs over time) by Fourier transform indicated that w1118 was associated with increased locomotor components at relatively high frequencies (> 0.1 Hz). The addition of multiple genomic copies of mw+ (2-4 copies) suppressed the high-frequency components. Lastly, the downregulation of w+ in neurons but not glial cells resulted in increased high-frequency components. We concluded that mutation of w modified the locomotion in adult flies by selectively increasing high-frequency locomotor components.