Figure 6. PDF-Secreting LN_V Clock Neuron Expression of Membrane-Tethered δ-ACTX-Hv1a Disrupts Free-Running Behavioral Rhythms.

Flies expressing membrane-tethered μO-MrVIA or δ-ACTX-Hv1a from indicated numbers of copies of UAS transgenes using pdf-GAL4 driver, as well as indicated nonexpressing parental UAS and pdf-GAL4 flies, were entrained in 12-h:12-h LD conditions before release into DD. Double-plotted normalized actograms depict averaged locomotor activity for indicated genotypes of flies from a representative experiment. Bar graph shows proportions of flies with the indicated behavioral phenotypes as assessed by Lomb-Scargle periodogram analysis of all pooled experiments. Control flies expressing membrane-tethered μO-MrVIA or parental transgenic lines not expressing any membrane-tethered peptide exhibit rhythmic locomotor activity with a single free-running rhythm. In contrast, most flies expressing membrane-tethered δ-ACTX-Hv1a exhibit arrhythmicity or complex rhythmicity. The averaged actograms reveal this complex rhythmicity as multiple superimposed free-running rhythms of different periods.

(A) The averaged actograms of all flies (including rhythmic and arrhythmic flies) of the indicated genotypes from a representative experiment are shown. pdf>μO-MrVIA flies exhibit locomotor rhythm with a single period of approximately 24.4 h. In contrast, pdf>δ-ACTX-Hv1a flies exhibit complex rhythmicity with simultaneously superimposed rhythms with periods of approximately 25 h and approximately 22 h.

(B) A summary of the percentages of flies exhibiting arrhythmic (red), complex rhythmic (yellow) and single rhythmic (blue) locomotor activity assayed over the first 14 d in DD. The difference in proportion of behavioral phenotypes between each of the control flies, either pdf>μO-MrVIA or UAS-toxin strain or pdf-GAL4 driver, and experimental pdf>δ-ACTX-Hv1a flies are each statistically significant by χ² test; for each of the χ² values, p < 0.0001. n, number of flies tested.