Mmmm\PVScer\UAS.T:Hsap\MYC expressing pre-synaptic terminals (expression under the control of Scer\GAL4elav-C155) exhibit altered Ca2+ dynamics compared with non-expressing controls. The transient Ca2+ increase induced by a single pre-synaptic action potential triggered by electrical stimulation of the motor nerve is smaller in Mmmm\PVScer\UAS.T:Hsap\MYC expressing terminals. The sustained Ca2+ increaase induced by a 10Hz train of action potentials is also quite different in Mmmm\PVScer\UAS.T:Hsap\MYC expressing terminals: the time to reach peak Ca2+ and the time constant of decay are each much longer in Mmmm\PVScer\UAS.T:Hsap\MYC expressing terminals.
Flies expressing 2 copies of Mmmm\PVScer\UAS.T:Hsap\MYC under the control of Scer\GAL4P2.4.Pdf have free-running periods slightly shorter than 24 hours, and these periods do not change over the course of 4 weeks in dark/dark conditions. In contrast, Scer\GAL4P2.4.Pdf expression of 4 and 6 copies of Mmmm\PVScer\UAS.T:Hsap\MYC results in longer free-running periods of just under 25 hours during the first week in dark/dark. Over the course of 4 weeks in dark/dark conditions, the free-running period of the 6x Mmmm\PVScer\UAS.T:Hsap\MYC flies continues to lengthen to over 27 hours by the fourth week. Interestingly, approximately 20% of these flies shift to a weak short-period rhythm during the fourth week in dark/dark.
After release into dark/dark conditions after 3 weeks in light/dark conditions, flies expressing 6 copies of Mmmm\PVScer\UAS.T:Hsap\MYC under the control of Scer\GAL4P2.4.Pdf immediately begin to free run with a period of approximately 27 hours, whereas 8x Mmmm\PVScer\UAS.T:Hsap\MYC flies free run with a period of approximately 24 hours.
Although Scer\GAL4P2.4.Pdf-driven expression of 6 copies of Mmmm\PVScer\UAS.T:Hsap\MYC results in the exhibition of robust 'morning' and 'evening' circadian anticipatory peaks of locomotor activity, increases are phase delayed relative to controls. There is a slight difference in the percentage of total activity that occurs in the dark versus the light, with Scer\GAL4P2.4.Pdf > 6x Mmmm\PVScer\UAS.T:Hsap\MYC flies engaging in more of their activity in the dark than controls.
Scer\GAL4P2.4.Pdf-driven expression of 6 copies of Mmmm\PVScer\UAS.T:Hsap\MYC results in significantly larger anticipation phase scores than controls for both the lights-on and lights-off transitions, indicating phase delays of activity increases for both morning and evening anticipation.
Expression of Mmmm\PVScer\UAS.T:Hsap\MYC in all clock neurons (under the control of Scer\GAL4tim.Scer\UAS) severely disrupts free-running rhythms of locomotor activity. These severe phenotypes include arrhythmicity and a change in behavior so no beam crossings are detected for a number of consecutive days, followed by resumption of substantial numbers of beam crossings. The average free-running period of rhythmic 2x Scer\GAL4tim.Scer\UAS > 4x Mmmm\PVScer\UAS.T:Hsap\MYC flies on the third week in dark/dark is 25.5 hours, approximately 2 hours longer than controls.
Pan-neuronal expression of Mmmm\PVScer\UAS.T:Hsap\MYC, under the control of Scer\GAL4elav-C155 does not induce any lethality, reduced lifespan, or other gross behavioral phenotypes.
Expression of Mmmm\PVScer\UAS.T:Hsap\MYC in the LNvs, under the control of Scer\GAL4P2.4.Pdf does not abolish the cyclic release of Pdf from their dorsomedial terminals.
Expression of Mmmm\PVScer\UAS.T:Hsap\MYC in the LNvs, under the control of Scer\GAL4P2.4.Pdf has little or no effect on free-running circadian period.