Originally published as Genetics Published Articles Ahead of Print on December 6, 2006.

Genetics, Vol. 175, 1197-1212, March 2007, Copyright © 2007
doi:10.1534/genetics.106.068411

Exploratory Activity in Drosophila Requires the kurtz Nonvisual Arrestin

Lingzhi Liu*, Ronald L. Davis{dagger} and Gregg Roman*,1

* Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204 and {dagger} Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77303

1 Corresponding author: Department of Biology and Biochemistry, University of Houston, 4800 Calhoun St., Houston, TX 77204.
E-mail: gwroman{at}uh.edu

When Drosophila adults are placed into an open field arena, they initially exhibit an elevated level of activity followed by a reduced stable level of spontaneous activity. We have found that the initial elevated component arises from the fly's interaction with the novel arena since: (1) the increased activity is independent of handling prior to placement within the arena, (2) the fly's elevated activity is proportional to the size of the arena, and (3) the decay in activity to spontaneous levels requires both visual and olfactory input. These data indicate that active exploration is the major component of elevated initial activity. There is a specific requirement for the kurtz nonvisual arrestin in the nervous system for both the exploration stimulated by the novel arena and the mechanically stimulated activity. kurtz is not required for spontaneous activity; kurtz mutants display normal levels of spontaneous activity and average the same velocities as wild-type controls. Inhibition of dopamine signaling has no effect on the elevated initial activity phase in either wild-type or krz1 mutants. Therefore, the exploratory phase of open field activity requires kurtz in the nervous system, but is independent of dopamine's stimulation of activity.