Figure 3: Drosophila expressing hAβPP and hBACE1 display disrupted day/night cycle. A-D: Elav-Gal4 driver was used to induce high levels of hAβPP and hBACE1 expression. A: High-level expression of hAβPP and hBACE1 reduced 24 hr total spontaneous activity. The graph shows total spontaneous activity/fly/24hr (five vials per group with 25 flies in each vial) for control and hAβPP/hBACE1 over-expressing flies. B: High levels of hAβPP and hBACE1 did not reduce nocturnal (12hr dark cycle) spontaneous activity. C: High levels of hAβPP and hBACE1 reduced diurnal (12hr light cycle) spontaneous activity. D: High-level expression of hAβPP and hBACE1 significantly increased the ratio of nocturnal to diurnal activity. Error bar indicates SEM, with n = 5 for each group (* indicates p < 0.05, *** indicates p<0.001, student t test).