Figure 2. Knocking down Dstac in PDF neurons lead to arrhythmic circadian rhythms in DD and elimination of the morning startle response in LD.

(A) Left, the percentage of rhythmic and arrhythmic flies from day 5 to 13 under DD. * denotes that the Dstac knockdown flies (Pdf-GAL4/y;UAS-Dstac-RNAi/+;UAS-DCR2/+) were significantly less rhythmic than all the other control groups (see Table 1). Numbers denote the number of flies that were rhythmic and arrhythmic. Center, actograms from a rhythmic and arrhythmic Dstac RNAi fly under DD. Right, the free-running periods of flies displaying significant periodicities under DD and constant temperature from day 5 to13 in constant darkness. * denotes that both Dstac knockdown flies with or without UAS-DCR2 displayed a slight but significant increase in the free-running periods when compared with the other control groups. Each dot represents an individual fly. (B) The activity histogram of each genotype from day 3 to 6 under LD showed no apparent change in morning and evening anticipation but a decrease morning startle response in Pdf-GAL4/y;UAS-Dstac-RNAi/+;UAS-DCR2/+ flies. (C) The morphology of Pdf:GAL4;UAS:Dstac^RNAi flies (2–3 days) appeared normal. (i) ​​yw,PDF-GAL4/y;+;+. (ii) yw,PDF-GAL4/y;+;UAS-DCR2/+. (iii) yw,PDF-GAL4/y;UAS-Dstac-RNAi/+;+. (iv) yw,PDF-GAL4/y;UAS-Dstac-RNAi/+;UAS-DCR2/+. (D) Left, the value of the normalized morning startle response (see Methods) of Dstac knock down flies was not significantly (ns) different from the value of 1 by Wilcoxon Signed Rank test. The values of the normalized morning startle responses of all the other control groups were significantly larger than 1. The morning anticipation (middle) and evening anticipation (right) from day 3 to 6 under LD was not significantly different between the Dstac knock down flies and controls (Dunn’s multiple comparison test).