Figure 3.

Primary branch fusion occurs following PVD dendrite injury. (A and B) Primary branch fusion following dendrotomy. L4 animal just after injury (red arrowhead in A) and 16-hr postsurgery (B). In (B), the severed distal and proximal ends of the primary branch reconnected (blue arrowhead). Bar, 10 μm. (C) Percentage of primary branch fusion during regeneration in wild-type (n = 14) and eff-1(ok1021) (n = 13) dendrotomized animals. Differences are not statistically significant (Fischer’s exact test). (D-H) PVD dendrite reconnection confirmed by Kaede photoconversion. A PVD primary dendrite of ser-2prom3::Kaede-expressing animals was dendrotomized, the animal was recovered for 23 hr, and the dendrite reconnection to its stump was assessed by Kaede photoconversion. The green Kaede form in the PVD cell body was irreversibly photoconverted to the red Kaede form using a 405 nm laser with the Mosaic system, and its spreading throughout the dendritic branches was followed 1 and 60 min postphotoconversion. Panels left to right are confocal reconstructions of a wild-type dendrotomized animal in the 488 green channel, 561 red channel, two channels merged view, and a schematic representation of the merged view. (D) Confocal reconstructions of the animal before dendrotomy, (E) immediately post dendrotomy, (F) 23-hr postdendrotomy, (G) 1-min post-Kaede photoconversion, and (H) 60-min post-Kaede photoconversion. Red Kaede form (cyan in merged and schematic representations), though diluted when spreading through the dendritic tree, can be observed beyond the reconnected site of injury in the distal part of the primary and higher ordered dendritic branches. Red arrowhead, site of injury; blue arrowhead, site of primary branch fusion. In the merged and schematic columns: magenta, green Kaede and cyan, photoconverted red Kaede. c, PVD cell body; NS, not significant.