CHARACTERIZATION OF SPONTANEOUS ELECTRICAL ACTIVITY IN DEVELOPING SPINAL MOTOR NEURONS OF ZEBRAFISH EMBRYOS

PAOLA V. PLAZAS; NICHOLAAS C. SPITZER

Kerala

Congreso; Human Frontiers in Science Program 2010 Annual Meeting; 2010

Human Frontiers in Science Program

Calcium signals are key for many processes during embryonic development. In the nervous system, fluctuations in intracellular calcium levels play important roles in proliferation, migration and neuronal differentiation. Moreover, spontaneous calcium transients in embryonic X. laevis spinal neurons have been shown to regulate processes including growth cone motility and neurotransmitter specification. However, our understanding of the way in which electrical activity affects the structure and function of developing circuits is quite limited. In this work, we have taken advantage of the optical transparency and rapid development of zebrafish (Danio rerio) to study the patterns of intracellular calcium signals in spinal primary motor neurons (PMN) of intact embryos during the entire process of axonogenesis, pathfinding and establishment of early connections. We simultaneously tracked axon outgrowth and formation of connections in vivo in transgenic zebrafish embryos that express selectively eGFP in motor neurons (Tg (Hb9:eGFP) ) between 16 (beginning of axon extension) and 24 hours post fertilization (when early connections are established with muscle) and performed calcium imaging during pathfinding behavior to determine the location and timing of electrical activity. Our results provide insight into when and where spontaneous electrical activity is expressed and its relation to the establishment of PMN precise stereotypical axonal branching patterns.