Synaptic plasticity is an elementary property of neuronal communication, which allows signal transfer between neurons to be modified in response to repeated use and/or external cues. Clock neurons feed circadian commands into the synaptically connected nervous system to modify physiological processes. Although it has been demonstrated that neuronal morphology and excitability may change rhythmically on a daily basis, surprisingly little is known about how such circadian plasticity may influence the molecular composition and function of synapses. This project will thus focus on basic questions relating to the influence of circadian rhythmicity on synaptic protein composition in Drosophila melanogaster.
Specifically, we will test whether rhythmic fluctuations of synaptic proteins convey functional synaptic changes. The expression of proteins that partake in transmitter release at presynaptic active zones and postsynaptic signal reception will be monitored and correlated with the functional state of individual synapses at different time points during the circadian cycle. To this end, fluorescence imaging and electrophysiological recordings of synapses will be conducted at single-cell resolution.
Furthermore, to monitor synaptic protein levels under disturbed circadian cycles we will
employ expression of Tobacco etch virus (TEV) protease in transgenic animals with engineered TEVcleavable clock protein versions to test the effects of instantaneous clock shutdown in individual neurons on the generation of rhythmic synaptic protein fluctuations.