Exploratory Activity in Drosophila Requires thekurtzNonvisual Arrestin

Abstract

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 krz 1 mutants. Therefore, the exploratory phase of open field activity requires kurtz in the nervous system, but is independent of dopamine's stimulation of activity.

Functional characterization of kurtz, a Drosophila non-visual arrestin, reveals conservation of GPCR desensitization mechanisms

“…The kurtz gene also possesses both amino-and carboxy-terminal arrestin domains and is 72% similar to the mammalian barr2 and 74% similar to barr1 (Roman et al, 2000). Loss-of-function mutations in this gene lead to lethality, and phenotypic analysis of the krz 1 mutation has demonstrated a role for this arrestin in antenna development, maintaining olfactory sensitivity, and a requirement for exploratory activity (Roman et al, 2000;Ge et al, 2006;Liu et al, 2007). We report herein that kurtz is a functional arrestin by virtue of translocation upon receptor activation, and akin to mammalian arrestins, delineates two classes of receptor molecules.…”

“…Proteins that participate in the breadth of signaling pathways, as do the arrestins, would be expected to have pleiotropic effects on development and physiology. We have previously ascertained that neural expression of krz is required for viability, proper development of the antenna, and wild type levels of olfactory sensitivity, exploration, and mechanically stimulated activity (Roman et al, 2000;Ge et al, 2006;Liu et al, 2007). However, krz expression is not limited to the nervous system, and it also regulates non-neural GPCRs.…”

The Genetic Basis of Emotional Behavior: Has the Time Come for a Drosophila Model?

“…Disruption of the MB function by both hydroxyurea ablation and blocking of neurotransmission has a strong impact on the frequency with which flies enter the central zone of an open field arena (Besson and Martin, 2005); specifically, these flies display a decrease in avoidance of the central zone. Flies, as well as rodents, also show an initially elevated level of activity when placed in an open field arena (Liu et al, 2007), followed by a decrease in activity to a spontaneous level dependent on both visual and olfactory input. In these studies, Liu and coworkers also observed the effect of centrophobism.…”

Gene–environment interplay inDrosophila melanogaster: Chronic food deprivation in early life affects adult exploratory and fitness traits

“…We measured this behavior in the open field, where the fly is put in a novel, open environment and its movement pattern is monitored (Methods). These tests have been used for decades to assess exploratory behavior in many species (34,35), as well as in D. melanogaster more recently (36)(37)(38)(39). Walking exploration is an ecologically valid measure because flies spend a considerable amount of time walking on fruits and other substrates in search of food, mates, and oviposition sites (40,41).…”