A ceiling with a 2.5-cm diameter hole at the center was firmly affixed to the walls of the arena. A loose lid like the previous circular arena was

laid on the top of the doughnut arena to create potential gaps at the edge of central zone. Even in the arena with a doughnut ceiling, flies spent the most amount of time near the edge (Fig. 6B; edge zone: 84.89 ±3.78%, middle zone: 13.98 ± 3.73%, central zone: 0.96 ± 0.26%). A robust boundary preference was Inhibitors,research,lifescience,medical retained even in the doughnut ceiling arena. Figure 6 Modeling the effect of turn angle on a fly’s position within the arenas. Each data point is the average of 20 simulations ± SEM. (A). Within a circular arena, there is a strong effect of limiting the fly’s field of motion (FoM; equals twice the … Drosophila Inhibitors,research,lifescience,medical display low turn angle trajectories One potential explanation

for a robust boundary preference is that the flies have a strong bias for moving in relatively straight lines, resulting in a centrifugal dispersal within the arena (Creed and Miller 1990). Although flies can rotate to make sharp turns of 100° or more in the arena, such instances may be very rare, especially while the fly is in motion (Strauss Inhibitors,research,lifescience,medical and Heisenberg 1990). Innate propensities for straight trajectories may represent a specific strategy to escape from distant threats, or may have evolved as a general response to slow and distant predators (Furuichi 2002; Eilam 2005). A physical inability or Inhibitors,research,lifescience,medical an innately low see more propensity to turn while walking would result in the animal being largely limited to the arena’s edge. To examine this possibility, we first measured the turning behavior of Canton-S flies within the arena. In central and edge zone, we examined the distribution and median of absolute turn angles of wild-type flies in an 8.4-cm diameter circular arena at 10 different sampling intervals (Supporting information). Different sampling intervals were considered as large sampling intervals can miss significant

turning behaviors in the trajectory while small sampling intervals Dichloromethane dehalogenase can capture Inhibitors,research,lifescience,medical a “wobble” like characteristic caused by changes in the tracking centroid of the fly without significant changes in the orientation during movement. Both in the edge and central zones, the median turn angle increased as the sampling interval increased (Fig. 5B). In the edge zone, the angle at which the turn angle distribution peaked increased from 3.6° to 12.6° (Supporting information and Fig. 5A) as the sampling interval increased from 0.1 to 1 sec. This indicates that different sampling intervals can give rise to different estimates of turn angles. However, for all of the 10 sampling intervals considered, the peaks of the distributions occur at small turn angles (maximum of 12.6°), which shows that flies prefer to execute small turn angles both in the edge and central zone.