IN-VIVO DYNAMICS OF AXON PATHFINDING IN THE DROSOPHILA CNS - A TIME-LAPSE STUDY OF AN IDENTIFIED MOTONEURON

We developed a system for time-lapse observation of identified neurons in the central nervous system (CNS) of the Drosophila embryo. Using t his system, we characterize the dynamics of filopodia and axon growth of the motorneuron RP2 as it navigates anteriorly through the CNS and then laterally along the intersegmental nerve (ISN) into the periphery . We find that both axonal extension and turning occur primarily throu gh the process of filopodial dilation. In addition, we used the GAL4-U AS system to express the fusion protein Tau-GFP in a subset of neurons , allowing us to correlate RP2's patterns of growth with a subset of a xons in its environment. In particular, we show that RP2's sharp later al turn is coincident with the nascent ISN. (C) 1998 John Wiley & Sons , Inc.