Steinert, J.R., Kuromi, H., Hellwig, A., Knirr, M., Wyatt, A.W., Kidokoro, Y., Schuster, C.M. (2006). Experience-dependent formation and recruitment of large vesicles from reserve pool.  Neuron 50(5): 723--733.

FBrf0193138

Research paper

The sizes and contents of transmitter-filled vesicles have been shown to vary depending on experimental manipulations resulting in altered quantal sizes. However, whether such a presynaptic regulation of quantal size can be induced under physiological conditions as a potential alternative mechanism to alter the strength of synaptic transmission is unknown. Here we show that presynaptic vesicles of glutamatergic synapses of Drosophila neuromuscular junctions increase in size as a result of high natural crawling activities of larvae, leading to larger quantal sizes and enhanced evoked synaptic transmission. We further show that these larger vesicles are formed during a period of enhanced replenishment of the reserve pool of vesicles, from which they are recruited via a PKA- and actin-dependent mechanism. Our results demonstrate that natural behavior can induce the formation, recruitment, and release of larger vesicles in an experience-dependent manner and hence provide evidence for an additional mechanism of synaptic potentiation.