February 16 2010

12:00 154 BSRB

Ecolunch: Alvaro Sagasti
UCLA, Department of MCDB

Sensitive fish in recovery: molecular control of axon degeneration and regeneration in zebrafish sensory neurons


Although many invertebrates can recover from damage to their nervous system, most vertebrate animals have a very limited ability to repair damaged neurons. My lab is interested in the molecular nature of the mechanisms that limit repair and, ultimately, why these mechanisms have evolved in vertebrates. To study axon development, degeneration and regeneration we use the peripheral touch-sensing neurons of zebrafish as a model. The rapid development, external fertilization, optical clarity, and molecular tractability of zebrafish larvae make them excellent models for studying these processes. We have developed a technique to precisely damage axons with a laser in live animals, and image their recovery with 3-D time-lapse imaging. Following axon damage, fragments of axons that are no longer attached to the cell body degenerate rapidly, while the proximal stump of the axon attempts to regenerate. Our studies of degeneration have identified molecular pathways that regulate axon degeneration, and suggest a functional requirement for degeneration in regeneration and axon pruning. Our studies of axon regeneration have identified a developmentally regulated molecular pathway that controls the ability of axons to regrow into former territory. A model will be presented suggesting that limits to regeneration arose as a consequence of the need to stabilize complex nervous systems.















































































































































































































































































































































































































































































































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