THE DISTRIBUTION OF COLLAPSIN-1 MESSENGER-RNA IN THE DEVELOPING CHICKNERVOUS-SYSTEM

Collapsin-1 is a secreted glycoprotein that inhibits the extension of specific growth cones in vitro. It has been hypothesized to serve as a repulsive guidance cue for extending growth cones in vivo. Here rye r eport the distribution of collapsin-1 message as demonstrated by in si tu hybridization using digoxigenin-labeled RNA probes in wholemounts a nd tissue sections. In the early chick brain collapsin-1 is expressed in specific regions of the retina, the olfactory bulb, and the diencep halon. In the hindbrain collapsin-1 is first expressed in rhombomere 5 and later in bilaterally symmetric rostrocaudal stripes. Collapsin-1 is expressed in high levels in the ventral horn of the spinal cord and in ventricular stripes that extend rostrally to the hindbrain. In the periphery, collapsin-1 is expressed in the dermamyotome and in ectode rm and epidermis. Based on collapsin's expression patterns we tested a xons extending from explants of ventral spinal cord and olfactory bulb for sensitivity to collapsin and show that the former are sensitive t o collapsin wheras the latter are not. The distribution of collapsin m RNA is consistent with it playing a role in the organization of sensor y axonal projections within the spinal cord and skin. (C) 1996 Academi c Press, Inc.