EN
Bruchpilot (BRP) protein is a scaffolding presynaptic protein that has been detected in the nervous system of Drosophila melanogaster. BRP assembles a presynaptic active zone and is responsible for calcium channel clustering and release of a neurotransmitter from synaptic vesicles. We have used the antibody nc82 against BRP to visualize presynaptic elements of tetrad synapses formed between the photoreceptor terminals and postsynaptic cells in the first optic neuropil (lamina) of the Drosophila optic lobe. In the lamina several circadian rhythms have been detected including rhythms in plasticity of synapses and neurons. The aim of this study was to examine whether BRP protein is involved in the circadian plasticity of tetrad synapses in the lamina. We have examined the BRP level, measured as the fluorescence intensity of immunolabeling, at different times of a light/dark (LD 12:12) regime and constant darkness (DD). We have found that BRP oscillates during the day. In LD 12:12 its level increases two times, in the morning and in the evening. However, these two peaks in BRP abundance are regulated differently. The morning peak is predominantly regulated by light since it is not present in norpA7 phototransduction mutant but it also depends on the circadian clock gene per. In turn the evening peak is regulated by the brain pacemaker. This peak is present in DD as well as in the norpA7 in LD but is absent in clock gene mutants.