FASCICLIN-I AND FASCICLIN-II HAVE DISTINCT ROLES IN THE DEVELOPMENT OF GRASSHOPPER PIONEER NEURONS

We have used a new technique, micro-CALI (chromophore-assisted laser i nactivation), to investigate the function of the neural cell adhesion molecules fasciclin I and II in the development of the grasshopper Ti1 neurons. Micro-CALI of fasciclin I results in defasciculation of the Ti1 axons similar to that achieved using large scale CALI (Jay and Kes hishian, 1990). The initial point of axon separation corresponds to th e site of laser irradiation, and defasciculation always continues dist al to this point. Micro-CALI of fasciclin II prevents the initiation o f Ti1 axon outgrowth but has no effect on fasciculation. This effect i s restricted to a 3 hr interval between cytokinesis and growth cone em ergence.